CA2332984A1 - Method of producing a thermoplastic polymer preform and an article produced therefrom - Google Patents
Method of producing a thermoplastic polymer preform and an article produced therefrom Download PDFInfo
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- CA2332984A1 CA2332984A1 CA002332984A CA2332984A CA2332984A1 CA 2332984 A1 CA2332984 A1 CA 2332984A1 CA 002332984 A CA002332984 A CA 002332984A CA 2332984 A CA2332984 A CA 2332984A CA 2332984 A1 CA2332984 A1 CA 2332984A1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/08—Metals
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
- B29C71/0063—After-treatment of articles without altering their shape; Apparatus therefor for changing crystallisation
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/04—Carbon
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/20—Oxides; Hydroxides
- C08K3/22—Oxides; Hydroxides of metals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2949/00—Indexing scheme relating to blow-moulding
- B29C2949/07—Preforms or parisons characterised by their configuration
- B29C2949/0715—Preforms or parisons characterised by their configuration the preform having one end closed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
- B29C49/02—Combined blow-moulding and manufacture of the preform or the parison
- B29C49/06—Injection blow-moulding
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
- B29C71/02—Thermal after-treatment
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
- B29K2105/25—Solid
- B29K2105/253—Preform
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
- B29K2995/0037—Other properties
- B29K2995/0041—Crystalline
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/20—Oxides; Hydroxides
- C08K3/22—Oxides; Hydroxides of metals
- C08K2003/2265—Oxides; Hydroxides of metals of iron
- C08K2003/2272—Ferric oxide (Fe2O3)
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
A method of producing a thermoplastic polymer preform having at least a crystalline finish portion comprising: (i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate increasing additive; (ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion; and (iii) exposing at least the finish portion of the preform to energy until crystallized.
Description
METHOD OF PRODUCING A THERMOPLASTIC POLYMER PREFORM
AND AN ARTICLE PRODUCED THEREFROM
This application claims priority to provisional patent application Serial No.
60/086,924, filed May 27, 1998, which is incorporated herein by reference in its entirety.
Background of the Invention Field of the Invention The present invention relates generally to the field of processing thermoplastic polymers and forming thermoplastic articles, and more particularly to a method of crystallizing a thermoplastic polymer by introducing a repeat rate-increasing additive into the thermoplastic polymer and processing same.
Descrip~:ion of Related Art Repeat Rate-Increasing Additives in Blow Molding Applications The use of polymer compositions, particularly compositions comprising polyethylene terephthalate) or copolymers thereof' (hereinafter collectively referred to as "PET"), for example in the form of films, bottles and other containers is well known. When bottles or other containers (hereinafter collectively referred to as "containers") are used for containing fluids, e.g., water, juices and carbonated drinks, container-forming compositions, in the form of polymer chips or pellets, are usually formed into the container shape in a two stage process. First, a container preform is injection molded; and second, either immediately or after a short storage period, the container preform is blown using compressed air into a mold which is in the final shape of the container. In the second stage of the process, the container preform is usually at or near ambient temperature, and it has to be heated to a temperature (for PET) of from about 85 ° C to about 120 ° C for the blow molding step. It is this "reheat" step which is usually the rate-determining step in the second stage of the process.
Accordingly, to increase the output of the container-forming processes, known energy-absorbing materials have been added to polymer compositions to increase the "reheat" rate of the polymer preform to be processed and made into a container. By increasing the reheat rate, less energy and time is required to heat the polymer preform to its glass transition temperature (Tg) and blow mold the preform thereby forming a container. Thus, the output of the container-forming processes is increased and less energy is required when using reheat rate-increasing additives.
I 0 Examples of such known energy-absorbing materials or reheat rate-increasing additives and compositions containing same are illustrated in U.S. Patents 4,408,004; 4,476,272; 4,535,118; 4,420,581; 5,419,936; and 5,529,744.
However, none of the processes utilizing reheat rate-increasing additives in thermoplastic polymers incorporate a reheat additive in a process where 1 S crystallization of a polymer containing the additive is carried out.
Previously, it was thought that there was no correlation or connection between reheat rate-increasing additives and polymer crystallization. In fact, prior to the present invention, there was no indication or expectation that such additives would have a significant affect on polymer crystallization, crystallization rates, or crystallization processes.
20 ?. Crystallization in Blow Molding Applications Thermoplastic polymers are often heat-treated to modify their material characteristics for improved performance when farming thermoplastic articles.
For example, the finishes (i.e., the upper portion typically comprising an opening and threads for engaging a cap) of PET preforms made to be blow molded into heat-set 25 containers are commonly crystallized by heating the finish of the preform, typically by exposure to infrared (IR) radiation. The purpose of subjecting heat-set preforms to this process, known as the Yoshino Process (U.S. Patent 5,261,545), is to convert the amorphous material in this region of the container to crystalline form, and WO 99/61514 PC'T/(JS99/11659 thereby prevent or reduce distortion of the finish of the heat-set container during hot filling.
In the Yoshino Process, an injection-molded preform is placed in a carrier which shields the body of the prefonm against exposure to crystallizing heat, but leaves the finishes exposed. The carrier containing the preform passes through an oven, where the preform finish is exposed to infrared energy for a sufficient amount of time to allow the finish to highly crystallize. High crystallinity provides dimensional stability to the finish and allows the resulting article or container to be hot-filled without suffering from thermal distortion in the finish.
However, not all polymers can be used for forming containers according to the Yoshino process. Copolymers, for example, have much slower crystallization rates than homopolymers. Therefore, using copolymers in the Yoshino process provides less throughput and requires more energy than homopolymers. Prior to the present invention, homopolymers were the predominant polymer used in crystallization processes.
Moreover, unfortunately, crystallizing a thermoplastic polymer preform is an additional step in the conventional container-forming process. An additional step, of course, creates longer and less efficient processing. Several factors effect the rate at which the crystallizing machine can process preforms, including polyester resin properties, oven efficiency, temperature the preform attains in the oven, and time spent in the oven. Accordingly, increasing efficiency by minimizing the amount of time and additional energy required to complete the container-forming process having a crystallization step is still needed.
Thus, heretofore, efficiency of a manufacturing facility crystallizing (at least a portion thereof) preforms processed under a Yoshino-type process was not enhanced by increasing the crystallization rate of preforms through the use of a reheat rate-increasing additive. In addition, only homopolymers were useful in applications requiring faster crystallization because copolymers were limited by their slower crystallization rates. Moreover, there was no indication or expectation that a reheat rate-increasing additive would have any affect on, let alone increase polymer (homopolymer and copolymer) crystallization, crystallization rates, or crystallization processes.
Summary of the Invention The method of the present invention uses a polymer/reheat rate-increasing additive composition to increase the rate of the polymer crystallization and, thus, the efficiency of a conventional container-forming process.
In accordance with the purposes) of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to a method of producing a thermoplastic polymer preform having at least a crystalline finish portion comprising (i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive; (ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion; and (iii) exposing at least the finish portion of the preform to energy until crystallized.
In another aspect, the present invention relates to a method of producing a thermoplastic polymer container having at least a crystalline finish portion, the method comprising (i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive; (ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion; (iii) exposing at least the finish portion of the preform to energy until crystallized; and (iv) blow molding the preform into a container, wherein the container has at least a crystalline finish portion.
In another aspect, the present invention relates to a method of crystallizing at least a finish portion of a thermoplastic polymer container comprising (i) providing a thermoplastic polymer container comprising a thermoplastic polymer and at least one reheat rate-increasing additive, wherein the container has a finish portion and a 27-06-2000y ~'''~ rrwa;roeru~c ~ nu~tr~tKU~ r.c. auaeaaidsu---v' n-~ui ~~e.o body portion; and (ii) exposing at least the finish pardon of the container to energy until crystallized.
In yet another aspect, the present invention relates to a methed of crystallizing a theranoplsstic polymer composition comprising (i) providing a thermoplastic polymer composition comprisipg a thermoplastic polymer and at least one repeat rate increasing additive; az~d (ii) exposing at least a portion of the composition to energy until crystallized.
In still anflther aspect, the prosent invention relates to a method for forming id caatainers comprising ahcat-set finish as n pardon of the container comprising (i) molding a container from a polymer comprising at least one repeat fate-improving addidva; and (ii) heat-setting at least a portion of the finish of the container.
Iu yet another aspect, the present invention re3ates to a container formed from a thermoplastic polymer comprising a body and a finish, wherein the finish is crystalline and contains a repeat rate-inareaeing additfve.
In other aspects, the present irwentiort relates to products made by the processes of the pzeseni invention Additional advantages of the inventionwill be act forth in part in the detailed description, including the figuxes, which follows, and is part will be obvious from the description, or may be teamed by practice of the invention, The advantages ofthe invention will be realized and attained by means of the eletneets and cotnhinations particularly pointed ou; in the appended claims. Yt is to be understood thact bath the fflrcgoing general description and ttie following detailed dsscriptian are exemplary $nd oxplenatory of preferred embodiments of the invention, and are not restrictive of the invention, as claimed.
AMENDED SHEET
- u-~ui:bd~~ hiom:nrtu~t r~ ~istnatK~;,"r.c. "'~''"' ~ 4U4tilfai~~fUu~~~U~ i uui r ni US 009911659 Detailed Descrip~on of the Invention The present invention may be understood mare readily by reference to the following detailed description of the invention, including the appended figures referred S to heceia, and t_~e examples provided therein. It is to be understflod that this invention is not limited to the specific processes and conditions described, as spxific processes andJar process conditions for processing plastic articles as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be timitiag.
i0 It must also be noted that, as usod in the specification and the appended claittu, the singular forces "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to processing a thermoplastic °'prcfann,"
"article," "contains" or "bottle" is intended to include the processing of a plurality of thermoplastic preforms, articles, containers or bottles.
1 ~ Ranges niay be expressed herein as from "about" or "approximately" one particular value aadlor to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value andlar tc the other particular value. Similarly, when value: are expressed as approximations, by use of the antecedent about, it will be understood that the particular 20 value forms another embodiment.
It has been disc:wercd that the rate card percent of crystallization of au amorphous th..~rmoplaatic polymer can be increased by incorporating into the AMENDED SHEET
polymer a reheat rate-increasing additive before processing by a crystallization machine. "Amorphous," for purposes of further defining the polymers of the present invention prior to crystallization, shall mean substantially noncrystalline. A
substantially noncrystalline polymer typically may have less than about S to 7 weight percent crystallinity. In particular, and by way of example, significant increases in the efficiency of processing heat-set PET container prefotms having a crystallized finish portion using the Yoshino process may be obtained by means of the method described herein.
In a broad sense, the process aspects of the invention may be defined as a method of producing molded articles comprising preparing a prefonn of thermoplastic polymer admixed with a reheat rate-increasing additive, subjecting the preform to radiant energy for a period of time necessary to raise its temperature to above the glass transition temperature of the polymer, and subsequently forming the preform into a desired shape. The term "glass transition temperature" is defined generally as the temperature at which the polymer changes from a glass-like material to a rubbery or leathery material.
The present invention is highly useful because 1 ) the method increases the amount of reheat energy which is absorbed by the preforms, and 2) the method increases (nucleates) the spherulitic crystalline growth rate during the step of preform/container crystallization. Spherulitic crystalline growth may be defined as the increase in spheroid crystalline bodies in the amorphous polymer.
Moreover, it has been surprisingly found that conventional reheat additives improve crystallization from the glass (providing improved processing during the finishing step), but do not noticeably affect the crystallization from the melt. This is particularly important because significant changes in crystallization from the melt would result in narrowed processing windows, which would make container production more difficult and less forgiving.
Thus, the method of the present invention provides preforms/containers having a higher or increased degree of crystallinity in a shorter processing time. The method of the present invention further provides a container-forming and/or container-processing step having increased output rates.
Presentlv Preferred Embodiments Briefly described, in one presently preferred embodiment, the present invention comprises a method of producing a thermoplastic polymer preform having at least a crystalline finish portion. The method comprises (i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive; (ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion; and (iii) exposing at least the finish portion of the preform to energy until crystallized. The invention also relates to a preform produced by the method of this embodiment.
In a second embodiment, the present invention relates to a method of producing a thermoplastic polymer container having at least a crystalline finish portion. This method comprises (i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive;
(ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion; (iii) exposing at least the finish portion of the preform to energy until crystallized; and (iv) blow molding the preform into a container, wherein the container has at least a crystalline finish portion. Preferably, the preform in step (iv) is at a temperature of from 80°C to 125 °C for blow molding. The invention also relates to a container produced by the method of this second embodiment.
In a third embodiment, the present invention relates to a method of crystallizing at least a finish portion of a thermoplastic polymer container comprising (i) providing a thermoplastic polymer container comprising a thermoplastic polymer and at least one reheat rate-increasing additive, wherein the container has a finish portion and a body portion; and (ii) exposing at least the finish portion of the container to energy until crystallized. This embodiment differs from that of exposing a preform to energy until crystallized. In this embodiment, at least the finish portion of a container, not a preform, is exposed to crystallizing energy.
The invention also relates to a container crystallized by the method of this third embodiment.
In yet another embodiment, the present invention relates to a method of crystallizing a thermoplastic polymer composition. The method comprises (i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive; and (ii) exposing at least a portion of the composition to energy until crystallized. This embodiment is different in that at least a portion of a composition having an additive is exposed to crystallizing energy and not a finish of a preform or a container. Preferably, the thermoplastic polymer composition is in the form of an article, more preferably a container, and even more preferably a bottle. Moreover, the invention relates to a bottle crystallized by the method of this embodiment.
In yet another embodiment, this invention relates to a method for forming containers comprising a heat-set finish on a portion of the container comprising (i) molding a container from a polymer comprising at least one reheat rate-improving additive; and (ii) heat-setting at least a portion of the finish of the container.
Preferably, the reheat rate-improving additive is carbon black, iron oxide or antimony metal. More preferably, the polymer comprises antimony metal in a concentration of about 20 ppm (ppm = parts per million by weight) or more, iron oxide in a concentration of less than about 12 ppm or carbon black in a concentration of less than about 10 ppm. The invention also relates to a container formed from the method of this embodiment.
In another embodiment, the present invention relates to a container formed from a thermoplastic polymer. The container comprises a body and a finish, wherein the finish is crystalline and contains a reheat rate-increasing additive.
Preferably, the finish is at least 25 weight percent crystalline. Preferably, the thermoplastic polymer used for forming the container is polyethylene terephthalate) or a copolymer thereof. The reheat rate-increasing additive preferably includes, but is not limited to, carbon black, iron oxide, antimony, tin, copper, silver, gold, palladium, platinum or a mixture thereof.
In all of the embodiments of this invention, the thermoplastic polymer composition is preferably transparent. Further, the thermoplastic polymer may comprise a homopolymer or comprise a copolymer. Preferably, the polymer is a polyester, and more preferably polyethylene terephthalate) or a copolymer thereof.
Exposure to energy to crystallize at least the finish portion of the preform or container having the additive is effected for about 25 seconds. The finish of the preform is at least 20 weight percent crystalline after exposure to crystallizing 10 energy. Preferably, the crystallizing radiant energy is at least partially within the infrared region of the energy spectrum. Further, at least a portion of the preform crystallizes at a rate faster than that of a prefonm without a reheat rate-increasing additive.
Thermo~astic Polvmers The thermoplastic polymer used in the invention is most usually a polyester, particularly a partially aromatic polyester, especially a polyester derived, at least mainly, from an aromatic diacid and an aliphatic (including cycloaliphatic) diol. A
preferred partially aromatic polyester is one which comprises at least 50 mole %, preferably at least 70 mole %, of ethylene terephthalate residues. The polyester may also contain residues derived from ethylene isophthalate, ethylene naphthalate, ethoxyethylene terephthalate, ethoxyethylene isophthalate or ethoxyethylene naphthalate.
Typically, polyesters such as polyethylene terephthalate polymer (PET) are made by reacting a glycol with a dicarboxylic acid as the free acid or its dimethyl ester to produce a prepolymer compound which is then polycondensed to produce the polyester. If required, the molecular weight of the polyester can then be increased further by solid state polymerization.
Suitable polyesters for the method of the present invention include crystallizable polyester homopolymers or copolymers that are suitable for use in containers and packaging, and particularly food packaging. The present invention provides accelerated crystallization rates for any thermoplastic resins, e.g., PET
containing a reheat rate-increasing additive. Suitable polyesters are generally known in the art and may be formed from aromatic dicarboxylic acids, esters of dicarboxylic acids, anhydrides of dicarboxylic esters, glycols, and mixtures thereof.
More preferably, the polyesters are formed from repeat units comprising terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, dimethyl-2,6-naphthalenedicarboxylate, 2,6-naphthalenedicarboxylic acid, ethylene glycol, diethylene glycol, 1,4-cyclohexane-dimethanol, 1,4-butanediol, and mixtures thereof.
The dicarboxylic acid component of the polyester may optionally be modified with one or more different dicarboxylic acids. Such additional dicarboxylic acids include aromatic dicarboxylic acids preferably having 8 to carbon atoms, aliphatic dicarboxylic acids preferably having 4 to I2 carbon atoms, or cycloaliphatic dicarboxylic acids preferably having 8 to 12 carbon atoms.
Examples of dicarboxylic acids to be included with terephthalic acid are:
phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, mixtures thereof and the like.
Preferably, the amount of said second dicarboxylic acid is less than 30 mole%
and more preferably less than about 15 mole%.
In addition, the glycol component may optionally be modified with one or more different glycols other than ethylene glycol. Such additional glycols include cycloaliphatic diols preferably having 6 to 20 carbon atoms or aliphatic diols preferably having 3 to 20 carbon atoms. Examples of such glycols include:
diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, propane-1,3-diol, butane-1,4-diol, pentane-I,S-diol, hexane-1,6-diol, 3-methylpentanediol-(2,4), methylpentanediol-(1,4), 2,2,4-trimethylpentane-diol-(1,3), 2-ethylhexanediol-(1,3), 2,2-diethylpropane-diol-(1,3), hexanediol-(1,3), 1,4-di-(hydroxyethoxy)-benzene, 2,2-bis-(4-hydroxycyclohexyl)-propane, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2-bis-(3-hydroxyethoxyphenyl)-propane, 2,2-bis-(4-hydroxypropoxyphenyl)-propane, mixtures thereof and the like. Polyesters may be prepared from two or more of the above glycols. Preferably, the amount of the second glycol is less than 30 mole% and more preferably less than about 15 mole%.
The thermoplastic resin may also contain small amounts of trifunctional or tetrafunctional comonomers such as trimeliitic anhydride, trimethylolpropane, pyromellitic dianhydride, pentaerythritol, and other polyester forming polyacids or polyols generally known in the art.
Rehear Rate-Increasing dditives As described above, the thermoplastic polymers according to this invention include at least one reheat rate-increasing additive. Reheat rate is defined as the change in average temperature of a molded part as a function of exposure to a radiant heat source for a specified time. Suitable reheat rate-increasing additives are well known in the art and include, preferably, black and gray body absorbers such as carbon black, antimony metal, iron oxide and the like, as well as near infrared absorbing dyes, including, but not limited to those disclosed in U.S.
97/15351, which is incorporated herein by reference.
The reheat rate-increasing additive should be present in an amount sufficient to improve the reheat rate of an unmodified polymer. The actual amount of reheat rate-increasing additive will vary depending on which additive is used.
Typically, in order to achieve the presently preferred crystallization of a preform or container, the thermoplastic polymer composition comprises the reheat rate-increasing additive in a concentration of about 1 to 300 ppm. The reheat rate-increasing additive may be typically any reheat rate-increasing additive used in the art, including, but not limited to, carbon black, iron oxide, antimony, tin, copper, silver, gold, palladium, platinum or a mixture thereof. However, only very small amounts of black body absorbers, like carbon black and iron oxide (about 10-12 ppm or less) may be necessary to achieve the desired crystallinity, but relatively large amounts of gray body absorbers like antimony metal may be necessary to achieve the same effect.
Typically, the polymer composition may comprise antimony metal in a concentration of at least 10 ppm.
The more effective concentration of the iron oxide, for example, is from about 1.0 to about 100 ppm, preferably from about 1 to about SO ppm with 1-30 ppm being most preferred. The iron oxide, preferably Fe,03 is used in very finely divided form e.g., from about 0.01 to about 200 pm, preferably from about 0.1 to about 10.0 ~tm, and most preferably from about 0.2 to about 5.0 pm. Such oxides are described, for example, on pages 323-349 of Pigment Handbook, Vol. 1, copyright 1973, John Wiley & Sons, Inc.
Iron oxide, for example, can be added to the polyester reactant system, during or after polymerization, to the polyester melt, or to the molding powder or pellets from which the bottle preforms are formed. For purposes of clarification, the bottle preforms are test tube shaped, injection moldings which are heated above the glass transition temperature of the polymer and then positioned in the bottle mold to receive the pressurized air through its open end. Such technology is well known to the art as shown in U.S. Pat. No. 3,733,309. Any radiant energy source may be employed, and the one used for heating the preforrns according to this invention is a quartz lamp, Model Q-1P, 650 W., 120 V., by Smith Victor Corp.
Suitable preferred metals for use as the additive according to the method of this invention include antimony, tin, copper, silver, gold, palladium and platinum or a mixture of two or more of these. It should also be appreciated that additional gray and black body absorbers including, but not limited to arsenic, cadmium, mercury and lead can also be used. However, for most applications, silver, gold, arsenic, cadmium, mercury, lead, palladium and platinum are either too expensive or environmentally hazardous and these metals are, consequently, not particularly preferred. Preferably, the metal is one or more of antimony, tin or copper with antimony being particularly advantageous.
Moreover, if metal is used as the reheat rate-increasing additive, the metal preferably is in particle form for ease of processing. The metal particles are preferably sufficiently fine for them not to be visible to the eye and have a range of sizes such that absorption of radiation occurs over a relatively wide part of the wavelength range and not just at one particular wavelength or over a narrow band.
The amount of metal particles present in the thermoplastic polymer S composition, as it is to be used in this invention, is a balance between the desired reduction in the reheat time of the polymer, the crystallization of the polymer and the amount of haze that is acceptable for a given application. Preferably, the amount of metal particles is from about 1 ppm to 300 ppm, more particularly from about 5 ppm to 150 ppm, and especially from about 10 ppm to 100 ppm. If desired, masterbatches of the polymer composition containing quantities of metal particles in far higher concentrations can be made for subsequent blending with polymer essentially free from the metal particles to achieve the desired levels of particles.
In polyester compositions, antimony is especially preferred because, in the form of antimony trioxide (antimony (III) oxide), it is a catalyst for the polymerization of the monomers used in the preparation of polyesters such as polyethylene terephthalate). As the polyester monomer melt is a slightly reducing environment, the polyesters may naturally have a very minor proportion of antimony metal present, e.g., upt o about 5-6 ppm. However, these low levels of antimony metal do not affect the reheat time significantly.
Also, although not required, additives and/or lubricants normally used in polyesters may be used if desired. Such additives include catalysts, colorants, pigments, glass fibers, fillers, impact modifiers, antioxidants, stabilizers, processing aids, flame retardants, acetaldehyde reducing compounds and the like.
Typical Techniaue Jfor Producing a Thermoplastic Container The method of the present invention is particularly suited for use in the production of a heat-set thermoplastic polymer (e.g., polyester) container. A
polyester preform, for example, is molded in the injection molding machine from a polyester resin containing a reheat rate-increasing additive. The preform is molded according to known techniques, whereby polyester pellets are dried and injection molded to produce clear, amorphous polyester preforms. The amorphous or "glassy"
preforms preferably comprise a threaded finish portion and a body portion. The finish portion is crystallized according to the present invention to prevent distortion of the finish upon further processing of the preform to produce a container, or upon heat-filling of the container. The body portion of the preform is typically processed, as by heated blow molding, to form a container having a desired shape and size.
According to the present invention, a portion of the preform is crystallized.
Preferably, only the finish is crystallized. Crystallization of the finish is usually an optional, and, until now, predominantly cumbersome stage of a preform-forming 10 process. However, by using a reheat rate-increasing additive in accordance with this invention, crystallization rates are dramatically increased rendering a crystallization stage more desirable in many container-forming applications.
Generally, crystallization involves exposing at least a portion of the preform finish to radiant heat from lamps in a row of ovens (across a spectrum which may 15 include the IR range) while protecting the body of the preform.
More particularly, after forming the preform, the preform is transported to a crystallization machine. The preforms are preferably loaded into carriers which shield the bodies of the preforms against exposure to crystallizing heat, but leave the finishes exposed. The Garners, containing the preforms, are passed through the crystallizing machine, where the preform finishes are exposed to infrared energy for a sufficient amount of time to allow the finishes to crystallize. This stage preferably involves exposing at least a portion of the preforrn finish to radiant heat from lamps in a row of ovens (across a spectrum that may include the IR range) while protecting the body of the preform. The finish is heated to temperatures at which the selected polyester crystallizes rapidly (for PET about 150°C to about 180°C). This results in a highly crystalline finish, i.e., spherulitic crystallinity levels at a minimum of about 20 weight percent. These high levels of crystallinity give dimensional stability to the finish that enable the resulting container to be hot-filled without suffering from thermal distortion in the finish region. Moreover, at least a portion of the preform crystallizes at a rate faster than that of a preform without a repeat rate-increasing additive.
Crystallization of the finish can be performed either to the preform (as in the Yoshino process), to a pre-bottle (as in the Sidel SRCF process outlined in U.S.
Patent No. 5,382,157), or to the actual heat-set bottle.
The desired container is preferably blow molded from the preform and heat-set, according to known techniques. In particular, the preform body (with or without the crystallized finish) is exposed lamps emitting radiant heat (which may include the IR range of the spectrum) until the preform has reached the appropriate temperature range for bottle blowing (from about 85 °C to about 120°C for PET).
The preform is removed from the oven and placed into a warm or hot blow mold and pressurized. The prefonm is thereby stretched into a container, preferably a bottle which is held against the warm or hot blow mold (therefore, the name "heat-set").
These bottles are typically designed to withstand hot-filling without shrinkage greater than about 1 % by volume. It is also desirable, although not required, to achieve a large degree of spherulitic crystallinity in the bottle sidewall in order to resist thermal distortion upon hot-filling of the bottle.
Crystallization of the bottle prefonms occurs through crystal nucleation.
Crystal nucleation in the preform is primarily heterogeneous. That is, the initial seed crystal forms at the surface of a pre-existing foreign particle in the resin, in the present case, a repeat rate-increasing additive. The additive, in accordance with the present invention, is a component intentionally added to promote increased repeat rates and nucleation. The density of crystal nucleation is controlled by the density of the additive as well as the rate at which seed crystals of polymer form at the surface of the additive, which is in turn influenced by material variables and temperature.
The following examples and experimental results are included to provide those of ordinary skill in the art with a complete disclosure and description of particular manners in which the present invention can be practiced and evaluated, and are intended to be purely exemplary of the invention and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.);
however, some errors and deviations may have occurred. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric.
Thus, it has been discovered that incorporating a reheat rate-increasing additive into PET, for example, dramatically accelerates the crystallization rate of PET from the glass. However, the decisive factor in determining whether this effect is useful in commercial package manufacturing processes is how long the PET
article must be exposed to crystallizing energy. In general, the longer the required exposure time to achieve accelerated crystallization, the less the process is commercially attractive.
The following example(s), in addition to the figures discussed above, illustrate that the required exposure time to achieve accelerated crystallization is much less for those compositions containing a reheat rate-increasing additive than those compositions without the additive.
Production of Heat-Set Thermoplastic Po[~rmer~ EST) Preforms 1 ) Injection Molding A polymer preform was injection molded. Specfically, preblended polymer (PET Homopolymer or modified PET) pellet concentration @ 50:1 let down ratio resulting in a 12 ppm level of black iron oxide was formed. Preforms were molded from the blend on a standard injection molding machine (4-cavity Husky LX-160).
This injection molding machine is well known to one of ordinary skill in the art and, as such, need not be described in detail here.
2) Reheat - Crystallizing The prefonms were crystallized on standard reheat equipment (Sidel SBO
2/3), which typically can be a stretch blow molding machine. This equipment is ' i'-uy:o4 ~ r~om:nrrmr ~ Kustn~rrcu;~N.i; '''.'''' . auabr~~ddu~~~~"" uui a i i US 009911659 well la~awn td one Qf ordinary skill in the art and, as such, need not be described in detail here. To sitnalate finish crystallization process, preforms v,~ere subj ccted to the fohowing various heating times andlor energy exposure levels to a point at which crystallization of the preform body oocurred:
(1) the radiant energy exposure was changed while holding production output rate constant (32.2 second periody (energy range: 250,000 to 475,000 watts); and (2) the exposure time was changed by varying production output rate while holding lamp intensity constant (output range: 8-13.5 partshninute}.
AND AN ARTICLE PRODUCED THEREFROM
This application claims priority to provisional patent application Serial No.
60/086,924, filed May 27, 1998, which is incorporated herein by reference in its entirety.
Background of the Invention Field of the Invention The present invention relates generally to the field of processing thermoplastic polymers and forming thermoplastic articles, and more particularly to a method of crystallizing a thermoplastic polymer by introducing a repeat rate-increasing additive into the thermoplastic polymer and processing same.
Descrip~:ion of Related Art Repeat Rate-Increasing Additives in Blow Molding Applications The use of polymer compositions, particularly compositions comprising polyethylene terephthalate) or copolymers thereof' (hereinafter collectively referred to as "PET"), for example in the form of films, bottles and other containers is well known. When bottles or other containers (hereinafter collectively referred to as "containers") are used for containing fluids, e.g., water, juices and carbonated drinks, container-forming compositions, in the form of polymer chips or pellets, are usually formed into the container shape in a two stage process. First, a container preform is injection molded; and second, either immediately or after a short storage period, the container preform is blown using compressed air into a mold which is in the final shape of the container. In the second stage of the process, the container preform is usually at or near ambient temperature, and it has to be heated to a temperature (for PET) of from about 85 ° C to about 120 ° C for the blow molding step. It is this "reheat" step which is usually the rate-determining step in the second stage of the process.
Accordingly, to increase the output of the container-forming processes, known energy-absorbing materials have been added to polymer compositions to increase the "reheat" rate of the polymer preform to be processed and made into a container. By increasing the reheat rate, less energy and time is required to heat the polymer preform to its glass transition temperature (Tg) and blow mold the preform thereby forming a container. Thus, the output of the container-forming processes is increased and less energy is required when using reheat rate-increasing additives.
I 0 Examples of such known energy-absorbing materials or reheat rate-increasing additives and compositions containing same are illustrated in U.S. Patents 4,408,004; 4,476,272; 4,535,118; 4,420,581; 5,419,936; and 5,529,744.
However, none of the processes utilizing reheat rate-increasing additives in thermoplastic polymers incorporate a reheat additive in a process where 1 S crystallization of a polymer containing the additive is carried out.
Previously, it was thought that there was no correlation or connection between reheat rate-increasing additives and polymer crystallization. In fact, prior to the present invention, there was no indication or expectation that such additives would have a significant affect on polymer crystallization, crystallization rates, or crystallization processes.
20 ?. Crystallization in Blow Molding Applications Thermoplastic polymers are often heat-treated to modify their material characteristics for improved performance when farming thermoplastic articles.
For example, the finishes (i.e., the upper portion typically comprising an opening and threads for engaging a cap) of PET preforms made to be blow molded into heat-set 25 containers are commonly crystallized by heating the finish of the preform, typically by exposure to infrared (IR) radiation. The purpose of subjecting heat-set preforms to this process, known as the Yoshino Process (U.S. Patent 5,261,545), is to convert the amorphous material in this region of the container to crystalline form, and WO 99/61514 PC'T/(JS99/11659 thereby prevent or reduce distortion of the finish of the heat-set container during hot filling.
In the Yoshino Process, an injection-molded preform is placed in a carrier which shields the body of the prefonm against exposure to crystallizing heat, but leaves the finishes exposed. The carrier containing the preform passes through an oven, where the preform finish is exposed to infrared energy for a sufficient amount of time to allow the finish to highly crystallize. High crystallinity provides dimensional stability to the finish and allows the resulting article or container to be hot-filled without suffering from thermal distortion in the finish.
However, not all polymers can be used for forming containers according to the Yoshino process. Copolymers, for example, have much slower crystallization rates than homopolymers. Therefore, using copolymers in the Yoshino process provides less throughput and requires more energy than homopolymers. Prior to the present invention, homopolymers were the predominant polymer used in crystallization processes.
Moreover, unfortunately, crystallizing a thermoplastic polymer preform is an additional step in the conventional container-forming process. An additional step, of course, creates longer and less efficient processing. Several factors effect the rate at which the crystallizing machine can process preforms, including polyester resin properties, oven efficiency, temperature the preform attains in the oven, and time spent in the oven. Accordingly, increasing efficiency by minimizing the amount of time and additional energy required to complete the container-forming process having a crystallization step is still needed.
Thus, heretofore, efficiency of a manufacturing facility crystallizing (at least a portion thereof) preforms processed under a Yoshino-type process was not enhanced by increasing the crystallization rate of preforms through the use of a reheat rate-increasing additive. In addition, only homopolymers were useful in applications requiring faster crystallization because copolymers were limited by their slower crystallization rates. Moreover, there was no indication or expectation that a reheat rate-increasing additive would have any affect on, let alone increase polymer (homopolymer and copolymer) crystallization, crystallization rates, or crystallization processes.
Summary of the Invention The method of the present invention uses a polymer/reheat rate-increasing additive composition to increase the rate of the polymer crystallization and, thus, the efficiency of a conventional container-forming process.
In accordance with the purposes) of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to a method of producing a thermoplastic polymer preform having at least a crystalline finish portion comprising (i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive; (ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion; and (iii) exposing at least the finish portion of the preform to energy until crystallized.
In another aspect, the present invention relates to a method of producing a thermoplastic polymer container having at least a crystalline finish portion, the method comprising (i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive; (ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion; (iii) exposing at least the finish portion of the preform to energy until crystallized; and (iv) blow molding the preform into a container, wherein the container has at least a crystalline finish portion.
In another aspect, the present invention relates to a method of crystallizing at least a finish portion of a thermoplastic polymer container comprising (i) providing a thermoplastic polymer container comprising a thermoplastic polymer and at least one reheat rate-increasing additive, wherein the container has a finish portion and a 27-06-2000y ~'''~ rrwa;roeru~c ~ nu~tr~tKU~ r.c. auaeaaidsu---v' n-~ui ~~e.o body portion; and (ii) exposing at least the finish pardon of the container to energy until crystallized.
In yet another aspect, the present invention relates to a methed of crystallizing a theranoplsstic polymer composition comprising (i) providing a thermoplastic polymer composition comprisipg a thermoplastic polymer and at least one repeat rate increasing additive; az~d (ii) exposing at least a portion of the composition to energy until crystallized.
In still anflther aspect, the prosent invention relates to a method for forming id caatainers comprising ahcat-set finish as n pardon of the container comprising (i) molding a container from a polymer comprising at least one repeat fate-improving addidva; and (ii) heat-setting at least a portion of the finish of the container.
Iu yet another aspect, the present invention re3ates to a container formed from a thermoplastic polymer comprising a body and a finish, wherein the finish is crystalline and contains a repeat rate-inareaeing additfve.
In other aspects, the present irwentiort relates to products made by the processes of the pzeseni invention Additional advantages of the inventionwill be act forth in part in the detailed description, including the figuxes, which follows, and is part will be obvious from the description, or may be teamed by practice of the invention, The advantages ofthe invention will be realized and attained by means of the eletneets and cotnhinations particularly pointed ou; in the appended claims. Yt is to be understood thact bath the fflrcgoing general description and ttie following detailed dsscriptian are exemplary $nd oxplenatory of preferred embodiments of the invention, and are not restrictive of the invention, as claimed.
AMENDED SHEET
- u-~ui:bd~~ hiom:nrtu~t r~ ~istnatK~;,"r.c. "'~''"' ~ 4U4tilfai~~fUu~~~U~ i uui r ni US 009911659 Detailed Descrip~on of the Invention The present invention may be understood mare readily by reference to the following detailed description of the invention, including the appended figures referred S to heceia, and t_~e examples provided therein. It is to be understflod that this invention is not limited to the specific processes and conditions described, as spxific processes andJar process conditions for processing plastic articles as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be timitiag.
i0 It must also be noted that, as usod in the specification and the appended claittu, the singular forces "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to processing a thermoplastic °'prcfann,"
"article," "contains" or "bottle" is intended to include the processing of a plurality of thermoplastic preforms, articles, containers or bottles.
1 ~ Ranges niay be expressed herein as from "about" or "approximately" one particular value aadlor to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value andlar tc the other particular value. Similarly, when value: are expressed as approximations, by use of the antecedent about, it will be understood that the particular 20 value forms another embodiment.
It has been disc:wercd that the rate card percent of crystallization of au amorphous th..~rmoplaatic polymer can be increased by incorporating into the AMENDED SHEET
polymer a reheat rate-increasing additive before processing by a crystallization machine. "Amorphous," for purposes of further defining the polymers of the present invention prior to crystallization, shall mean substantially noncrystalline. A
substantially noncrystalline polymer typically may have less than about S to 7 weight percent crystallinity. In particular, and by way of example, significant increases in the efficiency of processing heat-set PET container prefotms having a crystallized finish portion using the Yoshino process may be obtained by means of the method described herein.
In a broad sense, the process aspects of the invention may be defined as a method of producing molded articles comprising preparing a prefonn of thermoplastic polymer admixed with a reheat rate-increasing additive, subjecting the preform to radiant energy for a period of time necessary to raise its temperature to above the glass transition temperature of the polymer, and subsequently forming the preform into a desired shape. The term "glass transition temperature" is defined generally as the temperature at which the polymer changes from a glass-like material to a rubbery or leathery material.
The present invention is highly useful because 1 ) the method increases the amount of reheat energy which is absorbed by the preforms, and 2) the method increases (nucleates) the spherulitic crystalline growth rate during the step of preform/container crystallization. Spherulitic crystalline growth may be defined as the increase in spheroid crystalline bodies in the amorphous polymer.
Moreover, it has been surprisingly found that conventional reheat additives improve crystallization from the glass (providing improved processing during the finishing step), but do not noticeably affect the crystallization from the melt. This is particularly important because significant changes in crystallization from the melt would result in narrowed processing windows, which would make container production more difficult and less forgiving.
Thus, the method of the present invention provides preforms/containers having a higher or increased degree of crystallinity in a shorter processing time. The method of the present invention further provides a container-forming and/or container-processing step having increased output rates.
Presentlv Preferred Embodiments Briefly described, in one presently preferred embodiment, the present invention comprises a method of producing a thermoplastic polymer preform having at least a crystalline finish portion. The method comprises (i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive; (ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion; and (iii) exposing at least the finish portion of the preform to energy until crystallized. The invention also relates to a preform produced by the method of this embodiment.
In a second embodiment, the present invention relates to a method of producing a thermoplastic polymer container having at least a crystalline finish portion. This method comprises (i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive;
(ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion; (iii) exposing at least the finish portion of the preform to energy until crystallized; and (iv) blow molding the preform into a container, wherein the container has at least a crystalline finish portion. Preferably, the preform in step (iv) is at a temperature of from 80°C to 125 °C for blow molding. The invention also relates to a container produced by the method of this second embodiment.
In a third embodiment, the present invention relates to a method of crystallizing at least a finish portion of a thermoplastic polymer container comprising (i) providing a thermoplastic polymer container comprising a thermoplastic polymer and at least one reheat rate-increasing additive, wherein the container has a finish portion and a body portion; and (ii) exposing at least the finish portion of the container to energy until crystallized. This embodiment differs from that of exposing a preform to energy until crystallized. In this embodiment, at least the finish portion of a container, not a preform, is exposed to crystallizing energy.
The invention also relates to a container crystallized by the method of this third embodiment.
In yet another embodiment, the present invention relates to a method of crystallizing a thermoplastic polymer composition. The method comprises (i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive; and (ii) exposing at least a portion of the composition to energy until crystallized. This embodiment is different in that at least a portion of a composition having an additive is exposed to crystallizing energy and not a finish of a preform or a container. Preferably, the thermoplastic polymer composition is in the form of an article, more preferably a container, and even more preferably a bottle. Moreover, the invention relates to a bottle crystallized by the method of this embodiment.
In yet another embodiment, this invention relates to a method for forming containers comprising a heat-set finish on a portion of the container comprising (i) molding a container from a polymer comprising at least one reheat rate-improving additive; and (ii) heat-setting at least a portion of the finish of the container.
Preferably, the reheat rate-improving additive is carbon black, iron oxide or antimony metal. More preferably, the polymer comprises antimony metal in a concentration of about 20 ppm (ppm = parts per million by weight) or more, iron oxide in a concentration of less than about 12 ppm or carbon black in a concentration of less than about 10 ppm. The invention also relates to a container formed from the method of this embodiment.
In another embodiment, the present invention relates to a container formed from a thermoplastic polymer. The container comprises a body and a finish, wherein the finish is crystalline and contains a reheat rate-increasing additive.
Preferably, the finish is at least 25 weight percent crystalline. Preferably, the thermoplastic polymer used for forming the container is polyethylene terephthalate) or a copolymer thereof. The reheat rate-increasing additive preferably includes, but is not limited to, carbon black, iron oxide, antimony, tin, copper, silver, gold, palladium, platinum or a mixture thereof.
In all of the embodiments of this invention, the thermoplastic polymer composition is preferably transparent. Further, the thermoplastic polymer may comprise a homopolymer or comprise a copolymer. Preferably, the polymer is a polyester, and more preferably polyethylene terephthalate) or a copolymer thereof.
Exposure to energy to crystallize at least the finish portion of the preform or container having the additive is effected for about 25 seconds. The finish of the preform is at least 20 weight percent crystalline after exposure to crystallizing 10 energy. Preferably, the crystallizing radiant energy is at least partially within the infrared region of the energy spectrum. Further, at least a portion of the preform crystallizes at a rate faster than that of a prefonm without a reheat rate-increasing additive.
Thermo~astic Polvmers The thermoplastic polymer used in the invention is most usually a polyester, particularly a partially aromatic polyester, especially a polyester derived, at least mainly, from an aromatic diacid and an aliphatic (including cycloaliphatic) diol. A
preferred partially aromatic polyester is one which comprises at least 50 mole %, preferably at least 70 mole %, of ethylene terephthalate residues. The polyester may also contain residues derived from ethylene isophthalate, ethylene naphthalate, ethoxyethylene terephthalate, ethoxyethylene isophthalate or ethoxyethylene naphthalate.
Typically, polyesters such as polyethylene terephthalate polymer (PET) are made by reacting a glycol with a dicarboxylic acid as the free acid or its dimethyl ester to produce a prepolymer compound which is then polycondensed to produce the polyester. If required, the molecular weight of the polyester can then be increased further by solid state polymerization.
Suitable polyesters for the method of the present invention include crystallizable polyester homopolymers or copolymers that are suitable for use in containers and packaging, and particularly food packaging. The present invention provides accelerated crystallization rates for any thermoplastic resins, e.g., PET
containing a reheat rate-increasing additive. Suitable polyesters are generally known in the art and may be formed from aromatic dicarboxylic acids, esters of dicarboxylic acids, anhydrides of dicarboxylic esters, glycols, and mixtures thereof.
More preferably, the polyesters are formed from repeat units comprising terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, dimethyl-2,6-naphthalenedicarboxylate, 2,6-naphthalenedicarboxylic acid, ethylene glycol, diethylene glycol, 1,4-cyclohexane-dimethanol, 1,4-butanediol, and mixtures thereof.
The dicarboxylic acid component of the polyester may optionally be modified with one or more different dicarboxylic acids. Such additional dicarboxylic acids include aromatic dicarboxylic acids preferably having 8 to carbon atoms, aliphatic dicarboxylic acids preferably having 4 to I2 carbon atoms, or cycloaliphatic dicarboxylic acids preferably having 8 to 12 carbon atoms.
Examples of dicarboxylic acids to be included with terephthalic acid are:
phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, mixtures thereof and the like.
Preferably, the amount of said second dicarboxylic acid is less than 30 mole%
and more preferably less than about 15 mole%.
In addition, the glycol component may optionally be modified with one or more different glycols other than ethylene glycol. Such additional glycols include cycloaliphatic diols preferably having 6 to 20 carbon atoms or aliphatic diols preferably having 3 to 20 carbon atoms. Examples of such glycols include:
diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, propane-1,3-diol, butane-1,4-diol, pentane-I,S-diol, hexane-1,6-diol, 3-methylpentanediol-(2,4), methylpentanediol-(1,4), 2,2,4-trimethylpentane-diol-(1,3), 2-ethylhexanediol-(1,3), 2,2-diethylpropane-diol-(1,3), hexanediol-(1,3), 1,4-di-(hydroxyethoxy)-benzene, 2,2-bis-(4-hydroxycyclohexyl)-propane, 2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane, 2,2-bis-(3-hydroxyethoxyphenyl)-propane, 2,2-bis-(4-hydroxypropoxyphenyl)-propane, mixtures thereof and the like. Polyesters may be prepared from two or more of the above glycols. Preferably, the amount of the second glycol is less than 30 mole% and more preferably less than about 15 mole%.
The thermoplastic resin may also contain small amounts of trifunctional or tetrafunctional comonomers such as trimeliitic anhydride, trimethylolpropane, pyromellitic dianhydride, pentaerythritol, and other polyester forming polyacids or polyols generally known in the art.
Rehear Rate-Increasing dditives As described above, the thermoplastic polymers according to this invention include at least one reheat rate-increasing additive. Reheat rate is defined as the change in average temperature of a molded part as a function of exposure to a radiant heat source for a specified time. Suitable reheat rate-increasing additives are well known in the art and include, preferably, black and gray body absorbers such as carbon black, antimony metal, iron oxide and the like, as well as near infrared absorbing dyes, including, but not limited to those disclosed in U.S.
97/15351, which is incorporated herein by reference.
The reheat rate-increasing additive should be present in an amount sufficient to improve the reheat rate of an unmodified polymer. The actual amount of reheat rate-increasing additive will vary depending on which additive is used.
Typically, in order to achieve the presently preferred crystallization of a preform or container, the thermoplastic polymer composition comprises the reheat rate-increasing additive in a concentration of about 1 to 300 ppm. The reheat rate-increasing additive may be typically any reheat rate-increasing additive used in the art, including, but not limited to, carbon black, iron oxide, antimony, tin, copper, silver, gold, palladium, platinum or a mixture thereof. However, only very small amounts of black body absorbers, like carbon black and iron oxide (about 10-12 ppm or less) may be necessary to achieve the desired crystallinity, but relatively large amounts of gray body absorbers like antimony metal may be necessary to achieve the same effect.
Typically, the polymer composition may comprise antimony metal in a concentration of at least 10 ppm.
The more effective concentration of the iron oxide, for example, is from about 1.0 to about 100 ppm, preferably from about 1 to about SO ppm with 1-30 ppm being most preferred. The iron oxide, preferably Fe,03 is used in very finely divided form e.g., from about 0.01 to about 200 pm, preferably from about 0.1 to about 10.0 ~tm, and most preferably from about 0.2 to about 5.0 pm. Such oxides are described, for example, on pages 323-349 of Pigment Handbook, Vol. 1, copyright 1973, John Wiley & Sons, Inc.
Iron oxide, for example, can be added to the polyester reactant system, during or after polymerization, to the polyester melt, or to the molding powder or pellets from which the bottle preforms are formed. For purposes of clarification, the bottle preforms are test tube shaped, injection moldings which are heated above the glass transition temperature of the polymer and then positioned in the bottle mold to receive the pressurized air through its open end. Such technology is well known to the art as shown in U.S. Pat. No. 3,733,309. Any radiant energy source may be employed, and the one used for heating the preforrns according to this invention is a quartz lamp, Model Q-1P, 650 W., 120 V., by Smith Victor Corp.
Suitable preferred metals for use as the additive according to the method of this invention include antimony, tin, copper, silver, gold, palladium and platinum or a mixture of two or more of these. It should also be appreciated that additional gray and black body absorbers including, but not limited to arsenic, cadmium, mercury and lead can also be used. However, for most applications, silver, gold, arsenic, cadmium, mercury, lead, palladium and platinum are either too expensive or environmentally hazardous and these metals are, consequently, not particularly preferred. Preferably, the metal is one or more of antimony, tin or copper with antimony being particularly advantageous.
Moreover, if metal is used as the reheat rate-increasing additive, the metal preferably is in particle form for ease of processing. The metal particles are preferably sufficiently fine for them not to be visible to the eye and have a range of sizes such that absorption of radiation occurs over a relatively wide part of the wavelength range and not just at one particular wavelength or over a narrow band.
The amount of metal particles present in the thermoplastic polymer S composition, as it is to be used in this invention, is a balance between the desired reduction in the reheat time of the polymer, the crystallization of the polymer and the amount of haze that is acceptable for a given application. Preferably, the amount of metal particles is from about 1 ppm to 300 ppm, more particularly from about 5 ppm to 150 ppm, and especially from about 10 ppm to 100 ppm. If desired, masterbatches of the polymer composition containing quantities of metal particles in far higher concentrations can be made for subsequent blending with polymer essentially free from the metal particles to achieve the desired levels of particles.
In polyester compositions, antimony is especially preferred because, in the form of antimony trioxide (antimony (III) oxide), it is a catalyst for the polymerization of the monomers used in the preparation of polyesters such as polyethylene terephthalate). As the polyester monomer melt is a slightly reducing environment, the polyesters may naturally have a very minor proportion of antimony metal present, e.g., upt o about 5-6 ppm. However, these low levels of antimony metal do not affect the reheat time significantly.
Also, although not required, additives and/or lubricants normally used in polyesters may be used if desired. Such additives include catalysts, colorants, pigments, glass fibers, fillers, impact modifiers, antioxidants, stabilizers, processing aids, flame retardants, acetaldehyde reducing compounds and the like.
Typical Techniaue Jfor Producing a Thermoplastic Container The method of the present invention is particularly suited for use in the production of a heat-set thermoplastic polymer (e.g., polyester) container. A
polyester preform, for example, is molded in the injection molding machine from a polyester resin containing a reheat rate-increasing additive. The preform is molded according to known techniques, whereby polyester pellets are dried and injection molded to produce clear, amorphous polyester preforms. The amorphous or "glassy"
preforms preferably comprise a threaded finish portion and a body portion. The finish portion is crystallized according to the present invention to prevent distortion of the finish upon further processing of the preform to produce a container, or upon heat-filling of the container. The body portion of the preform is typically processed, as by heated blow molding, to form a container having a desired shape and size.
According to the present invention, a portion of the preform is crystallized.
Preferably, only the finish is crystallized. Crystallization of the finish is usually an optional, and, until now, predominantly cumbersome stage of a preform-forming 10 process. However, by using a reheat rate-increasing additive in accordance with this invention, crystallization rates are dramatically increased rendering a crystallization stage more desirable in many container-forming applications.
Generally, crystallization involves exposing at least a portion of the preform finish to radiant heat from lamps in a row of ovens (across a spectrum which may 15 include the IR range) while protecting the body of the preform.
More particularly, after forming the preform, the preform is transported to a crystallization machine. The preforms are preferably loaded into carriers which shield the bodies of the preforms against exposure to crystallizing heat, but leave the finishes exposed. The Garners, containing the preforms, are passed through the crystallizing machine, where the preform finishes are exposed to infrared energy for a sufficient amount of time to allow the finishes to crystallize. This stage preferably involves exposing at least a portion of the preforrn finish to radiant heat from lamps in a row of ovens (across a spectrum that may include the IR range) while protecting the body of the preform. The finish is heated to temperatures at which the selected polyester crystallizes rapidly (for PET about 150°C to about 180°C). This results in a highly crystalline finish, i.e., spherulitic crystallinity levels at a minimum of about 20 weight percent. These high levels of crystallinity give dimensional stability to the finish that enable the resulting container to be hot-filled without suffering from thermal distortion in the finish region. Moreover, at least a portion of the preform crystallizes at a rate faster than that of a preform without a repeat rate-increasing additive.
Crystallization of the finish can be performed either to the preform (as in the Yoshino process), to a pre-bottle (as in the Sidel SRCF process outlined in U.S.
Patent No. 5,382,157), or to the actual heat-set bottle.
The desired container is preferably blow molded from the preform and heat-set, according to known techniques. In particular, the preform body (with or without the crystallized finish) is exposed lamps emitting radiant heat (which may include the IR range of the spectrum) until the preform has reached the appropriate temperature range for bottle blowing (from about 85 °C to about 120°C for PET).
The preform is removed from the oven and placed into a warm or hot blow mold and pressurized. The prefonm is thereby stretched into a container, preferably a bottle which is held against the warm or hot blow mold (therefore, the name "heat-set").
These bottles are typically designed to withstand hot-filling without shrinkage greater than about 1 % by volume. It is also desirable, although not required, to achieve a large degree of spherulitic crystallinity in the bottle sidewall in order to resist thermal distortion upon hot-filling of the bottle.
Crystallization of the bottle prefonms occurs through crystal nucleation.
Crystal nucleation in the preform is primarily heterogeneous. That is, the initial seed crystal forms at the surface of a pre-existing foreign particle in the resin, in the present case, a repeat rate-increasing additive. The additive, in accordance with the present invention, is a component intentionally added to promote increased repeat rates and nucleation. The density of crystal nucleation is controlled by the density of the additive as well as the rate at which seed crystals of polymer form at the surface of the additive, which is in turn influenced by material variables and temperature.
The following examples and experimental results are included to provide those of ordinary skill in the art with a complete disclosure and description of particular manners in which the present invention can be practiced and evaluated, and are intended to be purely exemplary of the invention and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.);
however, some errors and deviations may have occurred. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric.
Thus, it has been discovered that incorporating a reheat rate-increasing additive into PET, for example, dramatically accelerates the crystallization rate of PET from the glass. However, the decisive factor in determining whether this effect is useful in commercial package manufacturing processes is how long the PET
article must be exposed to crystallizing energy. In general, the longer the required exposure time to achieve accelerated crystallization, the less the process is commercially attractive.
The following example(s), in addition to the figures discussed above, illustrate that the required exposure time to achieve accelerated crystallization is much less for those compositions containing a reheat rate-increasing additive than those compositions without the additive.
Production of Heat-Set Thermoplastic Po[~rmer~ EST) Preforms 1 ) Injection Molding A polymer preform was injection molded. Specfically, preblended polymer (PET Homopolymer or modified PET) pellet concentration @ 50:1 let down ratio resulting in a 12 ppm level of black iron oxide was formed. Preforms were molded from the blend on a standard injection molding machine (4-cavity Husky LX-160).
This injection molding machine is well known to one of ordinary skill in the art and, as such, need not be described in detail here.
2) Reheat - Crystallizing The prefonms were crystallized on standard reheat equipment (Sidel SBO
2/3), which typically can be a stretch blow molding machine. This equipment is ' i'-uy:o4 ~ r~om:nrrmr ~ Kustn~rrcu;~N.i; '''.'''' . auabr~~ddu~~~~"" uui a i i US 009911659 well la~awn td one Qf ordinary skill in the art and, as such, need not be described in detail here. To sitnalate finish crystallization process, preforms v,~ere subj ccted to the fohowing various heating times andlor energy exposure levels to a point at which crystallization of the preform body oocurred:
(1) the radiant energy exposure was changed while holding production output rate constant (32.2 second periody (energy range: 250,000 to 475,000 watts); and (2) the exposure time was changed by varying production output rate while holding lamp intensity constant (output range: 8-13.5 partshninute}.
3) 'Testing 'The crystahinity ofthc preforrns was determiner! by fast measuring gradient tube density, then converting density to weight percent crystallinity using the equations standard to the industry. Both measuring gradient tube density and converting density to cryatallinity using standard eQuatious are lmown to one of ordinary skill in the art and, as such, need not be described in detail here.
Comp~irstive Example A PET Homopolymer prefonn with approximately 12 ppm black iron oxide was 24 prepared by the method outlined above and subjected to approximately 475,000 watts of exposure of Iit over a 32.Z second period. The preform do~relopod 41 weight percent crystallinity.
The suns PET Homopolyrnex preform was prepared without the black iron oxide and subjected to the same exposure conditions. This prefortn developed only 10 2S weight percent crystatlinity.
lrxpeximental results were plQttcd, demonstrating the crysfallinity (weight percent) of various fortes of PET after exposure to radiant energy (watts) over the 32.2 second reheat period, and AMENDED SHEET
u~'uy:o5'~ ri~:nttmr ~ hu~tn~tKU~"N.i;. 1".°~ ~ 4U46~d~BdU~~~u~ uui ~e i5i US 009911659 demonstrating the crystatlinity (weight p ercent) of the PET Forms versus the production rate of the prefonns. The results refer to the following fortes of PET
manufactured and used by Eastman Chemical Corporation of Ki:~gspor~, Tennessee, U_B.A.:
a) 0.8 Its' (intrinsic viscosity) PET homopolymer (EASTAPAK p663) with and without a repeat rate-increasing additive;
b) 0.S IfV CHI3M (cyclohexane dimetlianol) modified PET (FASTAPAK (R) copolyester 992 iW) ~c~ith and without a repeat rate-increasing additive, and c) 4.8 ItV IPA (isapthalic acid) modified PET (at Eastman Chemical Company IO referred to internally as EA~TA.PAK (R) copolyester B-l I) with and without a repeat rate-increasing additive.
Threa forms of PET (all with 0.S It'd contpin a repeat rate-increasing additive in accordance with the method of this irwention: PET Homopolymer; CF~M
Modified PET; and IP 4 Modified PET. At the cod of the rehear period (32.2 seconds), wherein I ~ the PET forms are exposed to a final radiant energy of approximately x.50,000 watts, the three above-mentioned PET fotZns having the relxcat additive clearly have a higher crystal'linity than those without the repeat additive.
In addition, it is particularly surprising that the PET capoiymers ~CIrIDM and IPA modified) have a higher crystallinity tran the PET homapolymer without a repeat 20 additive. Copolymers, in general, do not crystallize as fast as homopolymers.
Therefore, the addition of a repeat rate-increasing additive dramatically increases the crystallinity of a homopalymer and a copolymer. Lxpcrimental evidence conf rntcd this proposition because the PET hornopolymer havitte the additivo has a higher crystallinity at the end of the r~heat period than the PET copolymers with an additive.
25 This result is to be expected given the crystallization rates of hcmopolymers versus copolymers.
AMENDED SHEET
-. v- v au ~ aJT . .j.V..pUUUJOOV-i TYa7 O~
27-06-2000 u~'~° ~ ~~°"'vttum s icu~r"srKU, r.i,. auasaaaeau s-uui r. ni US 009911659 A plot of crysta11i2ation of the PET polymers versus the production rate indicates again that the crystallization of the PBT polymers having the rcheat rate-increasirg additive is markedly increased over those PET polytrtcrs without the 5 additive. For example, at lower production rates (8-IO partsltuinute), the 0.8 PET
Hotnopolyrner and Q.81tV CHDM modified PET having the reheat additive show over double (at 8 parts/ntinute) the crystallinity of those PET polymers without the additive.
These results strongly suggest that 1 ) the rats of erystallizauon of the PET
polymers with tl~e additive is significantly higher than thaw without the additive, and 2) the 10 rehear rate-incrcasino additivo is the raesan for the dramatio increase is the rate of crystatli~ation. First, the PET palymexs are the same (i_e., 0.8 ItV and modiftGd vvth the same copolymers). Second, the processing conditions are the same (i.e., temperature, time, rate, exposure to et~~. Therefore, tine only experimental variable that distin~tishcs the results is the reheat rate-increasing additive, and the results show 15 that the additive dramatically improves crystallization of the PET
polymers.
Throughout this applicaxion, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which This invention pertains.
20 It will be apparent to those skilled in the art that various rraodifications and variations can oe made in the present invention without departing from fete scope or spirit of the invention. Other embodiments of the invention will be apparent to thaw sldiled in the art from consideration of the spec'tftcatian and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
AMENDED SHEET
Comp~irstive Example A PET Homopolymer prefonn with approximately 12 ppm black iron oxide was 24 prepared by the method outlined above and subjected to approximately 475,000 watts of exposure of Iit over a 32.Z second period. The preform do~relopod 41 weight percent crystallinity.
The suns PET Homopolyrnex preform was prepared without the black iron oxide and subjected to the same exposure conditions. This prefortn developed only 10 2S weight percent crystatlinity.
lrxpeximental results were plQttcd, demonstrating the crysfallinity (weight percent) of various fortes of PET after exposure to radiant energy (watts) over the 32.2 second reheat period, and AMENDED SHEET
u~'uy:o5'~ ri~:nttmr ~ hu~tn~tKU~"N.i;. 1".°~ ~ 4U46~d~BdU~~~u~ uui ~e i5i US 009911659 demonstrating the crystatlinity (weight p ercent) of the PET Forms versus the production rate of the prefonns. The results refer to the following fortes of PET
manufactured and used by Eastman Chemical Corporation of Ki:~gspor~, Tennessee, U_B.A.:
a) 0.8 Its' (intrinsic viscosity) PET homopolymer (EASTAPAK p663) with and without a repeat rate-increasing additive;
b) 0.S IfV CHI3M (cyclohexane dimetlianol) modified PET (FASTAPAK (R) copolyester 992 iW) ~c~ith and without a repeat rate-increasing additive, and c) 4.8 ItV IPA (isapthalic acid) modified PET (at Eastman Chemical Company IO referred to internally as EA~TA.PAK (R) copolyester B-l I) with and without a repeat rate-increasing additive.
Threa forms of PET (all with 0.S It'd contpin a repeat rate-increasing additive in accordance with the method of this irwention: PET Homopolymer; CF~M
Modified PET; and IP 4 Modified PET. At the cod of the rehear period (32.2 seconds), wherein I ~ the PET forms are exposed to a final radiant energy of approximately x.50,000 watts, the three above-mentioned PET fotZns having the relxcat additive clearly have a higher crystal'linity than those without the repeat additive.
In addition, it is particularly surprising that the PET capoiymers ~CIrIDM and IPA modified) have a higher crystallinity tran the PET homapolymer without a repeat 20 additive. Copolymers, in general, do not crystallize as fast as homopolymers.
Therefore, the addition of a repeat rate-increasing additive dramatically increases the crystallinity of a homopalymer and a copolymer. Lxpcrimental evidence conf rntcd this proposition because the PET hornopolymer havitte the additivo has a higher crystallinity at the end of the r~heat period than the PET copolymers with an additive.
25 This result is to be expected given the crystallization rates of hcmopolymers versus copolymers.
AMENDED SHEET
-. v- v au ~ aJT . .j.V..pUUUJOOV-i TYa7 O~
27-06-2000 u~'~° ~ ~~°"'vttum s icu~r"srKU, r.i,. auasaaaeau s-uui r. ni US 009911659 A plot of crysta11i2ation of the PET polymers versus the production rate indicates again that the crystallization of the PBT polymers having the rcheat rate-increasirg additive is markedly increased over those PET polytrtcrs without the 5 additive. For example, at lower production rates (8-IO partsltuinute), the 0.8 PET
Hotnopolyrner and Q.81tV CHDM modified PET having the reheat additive show over double (at 8 parts/ntinute) the crystallinity of those PET polymers without the additive.
These results strongly suggest that 1 ) the rats of erystallizauon of the PET
polymers with tl~e additive is significantly higher than thaw without the additive, and 2) the 10 rehear rate-incrcasino additivo is the raesan for the dramatio increase is the rate of crystatli~ation. First, the PET palymexs are the same (i_e., 0.8 ItV and modiftGd vvth the same copolymers). Second, the processing conditions are the same (i.e., temperature, time, rate, exposure to et~~. Therefore, tine only experimental variable that distin~tishcs the results is the reheat rate-increasing additive, and the results show 15 that the additive dramatically improves crystallization of the PET
polymers.
Throughout this applicaxion, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which This invention pertains.
20 It will be apparent to those skilled in the art that various rraodifications and variations can oe made in the present invention without departing from fete scope or spirit of the invention. Other embodiments of the invention will be apparent to thaw sldiled in the art from consideration of the spec'tftcatian and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
AMENDED SHEET
Claims (42)
1. A method of producing a thermoplastic polymer preform having at least a crystalline finish portion comprising:
(i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat tate-increasing additive;
(ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion; and (iii) exposing at least the finish portion of the preform to energy until crystallized.
(i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat tate-increasing additive;
(ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion; and (iii) exposing at least the finish portion of the preform to energy until crystallized.
2. The method of Claim 1, wherein the thermoplastic polymer composition is amorphous.
3. The method of Claim 1, wherein the thermoplastic polymer comprise a homopolymer.
4. The method of Claim 1, wherein the thermoplastic polymer comprises a copolymer.
5. The method of Claim 1, wherein the thermoplastic polymer comprises a polyester.
6. The method of Claim 5, wherein the polyester is poly(ethylene terephthalate) or a copolymer thereof.
7. The method of Claim 1, wherein the thermoplastic polymer composition comprises the reheat rate-increasing additive in a concentration of from 1 to ppm.
8. The method of Claim 1, wherein the reheat rate-increasing additive is carbon black, dyes, iron oxide, antimony, tin, copper, silver, gold, arsenic, cadmium, mercury, lead, palladium, platinum or a mixture thereof.
9. The method of Claim 1, wherein the reheat rate-increasing additive comprises iron oxide in a concentration of from 1 to 60 ppm.
10. The method of Claim 9, wherein the iron oxide is Fe2O3 and has a particle size from 0.1 10µm.
11. The method of Claim 1, wherein the reheat rate-increasing additive comprises antimony metal in a concentration of at least 3 ppm.
12. The method of Claim 1, wherein step (iii) is effected for at least 25 seconds.
13. The method of Claim 1, wherein the finish portion of the preform is at least 25 weight percent crystalline after step (iii).
14. The method of Claim 1, wherein only the finish portion is exposed to energy to crystallize it in step (iii).
15. The method of Claim 1, wherein the energy is radiant energy,
16. The method of Claim 15, wherein the radiant energy is at least partially within the infrared region of the energy spectrum.
17. A preform produced by the method of Claim 1,
18. A method of crystallizing at least a finish portion of a thermoplastic polymer container comprising:
(i) providing a thermoplastic polymer container comprising a thermoplastic polymer and at least one reheat rate-increasing additive, wherein the container has a finish portion and a body portion; and (ii) exposing at least the finish portion of the container to energy until crystallized.
(i) providing a thermoplastic polymer container comprising a thermoplastic polymer and at least one reheat rate-increasing additive, wherein the container has a finish portion and a body portion; and (ii) exposing at least the finish portion of the container to energy until crystallized.
19. The method of Claim 18, wherein the thermoplastic polymer is amorphous.
20. The method of Claim 18, wherein the thermoplastic polymer comprises a polyester homopolymer or copolymer.
21. The method of Claim 20, wherein the polyester is poly(ethylene terephthalate) or a copolymer thereof.
22. A container crystallized by the method of Claim 18.
23. A method of producing a thermoplastic polymer container having at least a crystalline finish portion comprising:
(i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive;
(ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion;
(iii) exposing at least the finish portion of the preform to energy until crystallized; and (iv) blow molding the preform into a container, wherein the container has at least a crystalline finish portion.
(i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive;
(ii) forming a preform from the thermoplastic polymer composition, wherein the preform comprises a finish portion and a body portion;
(iii) exposing at least the finish portion of the preform to energy until crystallized; and (iv) blow molding the preform into a container, wherein the container has at least a crystalline finish portion.
24. The method of Claim 23, wherein the thermoplastic polymer composition is amorphous.
25. The method of Claim 23, wherein the preform in step (iv) is at a temperature of from 80°C to 125°C.
26. A container produced by the method of Claim 23.
27. A method of crystallizing a thermoplastic polymer composition comprising:
(i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive; and (ii) exposing at least a portion of the composition to energy until crystallized.
(i) providing a thermoplastic polymer composition comprising a thermoplastic polymer and at least one reheat rate-increasing additive; and (ii) exposing at least a portion of the composition to energy until crystallized.
28. The method of Claim 27, wherein the thermoplastic polymer composition is amorphous.
29. The method of Claim 27, wherein the thermoplastic polymer composition is in the form of an article.
30. The method of Claim 29, wherein the article is a container.
31 . The method of Claim 30, wherein the container is a bottle.
32.A bottle crystallized by the method of Claim 31,
33.A method for forming a container comprising a heat set finish on a portion of the container comprising:
(i) molding a container from a polymer comprising at least one reheat rate-improving additive; and (ii) heat setting at least a portion of the finish of the container against a warm or hot blow mold.
(i) molding a container from a polymer comprising at least one reheat rate-improving additive; and (ii) heat setting at least a portion of the finish of the container against a warm or hot blow mold.
34. The method of Claim 33, wherein the reheat rate-improving additive is carbon black, iron oxide or antimony metal.
35. The method of Claim 33, wherein the polymer comprises antimony metal in a concentration of 20 ppm or more.
36. The method of Claim 33, wherein the polymer comprises iron oxide in a concentration of greater than 0 to less than 12 ppm.
37. The method of Claim 33, wherein the polymer comprises carbon black in a concentration of greater than 0 to loss than 12 ppm.
38. A container formed by the method of Claim 33.
39. A container formed from a thermoplastic polymer comprising:
a body; and a finish, wherein the finish is crystalline and contains a reheat rate-increasing additive.
a body; and a finish, wherein the finish is crystalline and contains a reheat rate-increasing additive.
40. The container of Claim 39, wherein the thermoplastic polymer is poly(ethylene terephthalate) or a copolymer thereof.
41. The method of Claim 39, wherein the reheat rate-increasing additive is carbon black, iron oxide, antimony, tin, copper, silver, gold, arsenic, cadmium, mercury, lead, palladium, platinum or a mixture thereof.
42. The method of Claim 39, wherein the finish is at least 20 weight percent crystalline.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US8692498P | 1998-05-27 | 1998-05-27 | |
| US60/086,924 | 1998-05-27 | ||
| PCT/US1999/011659 WO1999061514A1 (en) | 1998-05-27 | 1999-05-27 | Method of producing a thermoplastic polymer preform and an article produced therefrom |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2332984A1 true CA2332984A1 (en) | 1999-12-02 |
Family
ID=22201786
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002332984A Abandoned CA2332984A1 (en) | 1998-05-27 | 1999-05-27 | Method of producing a thermoplastic polymer preform and an article produced therefrom |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP1082377A1 (en) |
| JP (1) | JP2002516204A (en) |
| CN (1) | CN1311807A (en) |
| AR (1) | AR018393A1 (en) |
| BR (1) | BR9910709A (en) |
| CA (1) | CA2332984A1 (en) |
| WO (1) | WO1999061514A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8552099B2 (en) | 2004-03-30 | 2013-10-08 | Colormatrix Europe Limited | Polymeric materials and additives therefor |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030031814A1 (en) * | 2000-04-28 | 2003-02-13 | Hutchinson Gerald A. | Bottles and preforms having a crystalline neck |
| US7479517B2 (en) * | 2003-11-28 | 2009-01-20 | Futura Polyesters Ltd. | Process for the preparation of fast reheat (FRH) bottle grade polyethyleneterephthalate (PET) resin |
| US7358322B2 (en) * | 2004-03-09 | 2008-04-15 | Eastman Chemical Company | High IV melt phase polyester polymer catalyzed with antimony containing compounds |
| US7816436B2 (en) * | 2004-11-08 | 2010-10-19 | INVISTA North America S.à.r.l. | Carbon black with large primary particle size as reheat additive for polyester and polypropylene resins |
| CN111773762B (en) * | 2020-06-09 | 2022-03-08 | 江苏恒科新材料有限公司 | Energy-conserving compact polyester chip crystallization drying system |
| EP4442764A1 (en) * | 2021-11-30 | 2024-10-09 | Mitsubishi Chemical Corporation | Resin composition, molded article, composite, and metal/resin composite |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4535118A (en) * | 1982-02-24 | 1985-08-13 | The Goodyear Tire & Rubber Company | High clarity, low haze polyesters having reduced infrared heat-up times |
| GB8926631D0 (en) * | 1989-11-24 | 1990-01-17 | Ici Plc | Polymer compositions |
| WO1994010242A1 (en) * | 1992-10-26 | 1994-05-11 | Allied-Signal Inc. | Nucleating system for polyesters and articles formed therefrom |
-
1999
- 1999-05-27 CA CA002332984A patent/CA2332984A1/en not_active Abandoned
- 1999-05-27 CN CN99809077.8A patent/CN1311807A/en active Pending
- 1999-05-27 EP EP99925890A patent/EP1082377A1/en not_active Withdrawn
- 1999-05-27 AR ARP990102497A patent/AR018393A1/en unknown
- 1999-05-27 JP JP2000550911A patent/JP2002516204A/en active Pending
- 1999-05-27 WO PCT/US1999/011659 patent/WO1999061514A1/en not_active Application Discontinuation
- 1999-05-27 BR BR9910709-0A patent/BR9910709A/en not_active Application Discontinuation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8552099B2 (en) | 2004-03-30 | 2013-10-08 | Colormatrix Europe Limited | Polymeric materials and additives therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2002516204A (en) | 2002-06-04 |
| AR018393A1 (en) | 2001-11-14 |
| WO1999061514A1 (en) | 1999-12-02 |
| CN1311807A (en) | 2001-09-05 |
| EP1082377A1 (en) | 2001-03-14 |
| BR9910709A (en) | 2001-01-30 |
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Legal Events
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| EEER | Examination request | ||
| FZDE | Discontinued |