Highly modified polyesters for containers

Abstract

A polyester resin for use in a process in which, during an expansion step, an incompressible fluid is injected through an opening of a preform, formed of the polyester resin, to form a container. The polyester resin includes a crystallizable polyester polymer wherein the polyester polymer is comprised of acid moieties and glycol moieties, with at least 85% of the total moles of acid moieties being terephthalate derived from terephthalic acid or its dimethyl ester and at least 85% of the total moles of glycol moieties derived from ethylene glycol. At least 2% of the total moles of acid plus glycol moieties are derived from a primary comonomer with the mole percents of the acid plus glycol moieties totaling 100 mole %.

Claims

1. A process to form a polyester container from a polyester preform having an opening at the level of a neck, the process comprising utilizing an expansion step carried out with a cavity or a mold, wherein, during said expansion step, an incompressible fluid is injected through the opening of said preform to form said container; characterized in that the polyester preform comprises a crystallizable polyester polymer comprised of acid moieties and glycol moieties, with at least 85% of the total moles of acid moieties being terephthalate derived from terephthalic acid or its dimethyl ester and at least 85% of the total moles of glycol moieties derived from ethylene glycol and with at least 2% of the total moles of acid plus glycol moieties derived from a primary comonomer with the mole percents of the acid plus glycol moieties totaling 100 mole %, wherein the primary comonomer has functional groups connected by a non-cyclic structure containing more than two carbon atoms, and wherein the crystallizable polyester has a melting temperature in the range of 235 to 242 C. and a glass transition temperature in the range of 60 C. to 73 C.

2. The process of claim 1, wherein the primary comonomer is selected from the group consisting of aliphatic diacids or their dimethyl esters.

3. The process of claim 1, wherein the primary comonomer is selected from the group consisting of sebacic acid, adipic acid, and their respective dimethyl esters.

4. The process of claim 1, wherein the primary comonomer is present in the range of 1 to 10 mole % of the total moles of acid moieties in the crystallizable polyester.

5. The process of claim 1, wherein the cyrstallizable polyester has an intrinsic viscosity in the range of 0.50 to 0.95 dl/g.

6. The process of claim 1, wherein the crystallizable polyester has a glass transition temperature in the range of 63 C. to 71 C.

7. A process for forming a polyester container from a polyester preform, comprising placing the preform within a cavity of a mold and expanding the preform within the cavity of the mold by introducing a compressible fluid under a blow pressure into the preform located in the mold and stretching the preform to assume the shape of the surrounding mold cavity, wherein the polyester preform comprises a crystallizable polyester polymer wherein the polyester polymer is comprised of acid moieties and glycol moieties, with at least 85% of the total moles of acid moieties being terephthalate derived from terephthalic acid or its dimethyl ester and at least 85% of the total moles of glycol moieties derived from the ethylene glycol and with at least 2% of the total moles of acid plus glycol moieties derived from a primary comonomer with the mole percents of the acid plus glycol moieties totaling 100 mole %; and wherein the blow pressure is at 10% less than the blow pressure used to stretch a reference preform into the same mold cavity, wherein the reference preform is made with 98% of the total moles of acid moieties being terephthalate moieties, 2% of the total moles of acid moieties being isophthalate moieties and 100% of the total moles of glycol moieties derived from ethylene glycol.

8. The process of claim 7, wherein the primary comonomer is selected from the group consisting of the aliphatic diacids or their dimethyl esters.

9. The process of claim 7, wherein the primary comonomer is selected from the group consisting of sebacic acid, adipic acid and their respective dimethyl ester.

10. The process of claim 7, wherein the primary comonomer is present in the range of 1 to 10 mole % of the total acid moieties in the crystallizable polyester.

11. The process of claim 7, wherein the crystallizable polyester has an intrinsic viscosity in the range of 0.50 to 0.95 dl/g.

12. The process of claim 7, wherein the crystallizable polyester has a melting temperature in the range of 235 C. to 242 C.

13. The process of claim 7, wherein the cyrstallizable polyester has a glass transition temperature in the range of 60 C. to 73 C.

14. The process of claim 1, wherein the primary comonomer is selected from the group consisting of sebacic acid, adipic acid, sebacic dimethyl ester, adipic dimethyl ester, saturated dimer acids, polyethylene glycols, poly(tetramethylene ether) glycols, polypropylene glycols, 1,6-hexanediol, long chain dimer diol, isopropylene glycol, and combinations thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a prior art schematic depiction corresponding to FIG. 1 of WO 2009075791 of a heated preform passed into a mold station and being subject to an optional sterilization step, wherein a pressure source including a piston-like device begins to move upward, drawing liquid into the pressure source in accordance with the teachings of WO 2009075791.

(2) FIG. 2 is a prior art schematic depiction corresponding to FIG. 2 of WO 2009075791 of the system illustrated in FIG. 1 wherein the mold halves close around the preform and liquid continues to accumulate in the pressure source.

(3) FIG. 3 is a prior art schematic depiction corresponding to FIG. 3 of WO 2009075791 of the system illustrated in FIG. 2 wherein a stretch rod extends into the preform to initiate mechanical stretching and wherein fluid continues to accumulate in the pressure source.

(4) FIG. 4 is a prior art schematic depiction corresponding to FIG. 4 of WO 2009075791 of the system of FIG. 3 wherein the stretch rod stretches the preform and wherein fluid has been fully accumulated in the pressure source.

(5) FIG. 5 is a prior art schematic depiction corresponding to FIG. 5 of WO 2009075791 of the system of FIG. 4 wherein the piston-like device drives the liquid from the pressure source to the preform thereby expanding the preform toward the walls of the mold cavity.

(6) FIG. 6 is a prior art schematic depiction corresponding to FIG. 6 of WO 2009075791 of the system of FIG. 5 wherein the piston-like device has been fully actuated thereby completely transferring an appropriate volume of liquid to the newly formed container and wherein the stretch rod is withdrawing; and

(7) FIG. 7 is a prior art schematic depiction corresponding to FIG. 7 of WO 2009075791 of the system of FIG. 6 wherein the mold halves separate and the piston-like device begins to draw liquid into the pressure source in preparation for the next cycle.

(8) FIG. 8 is a prior art schematic corresponding to the single figure of United States Patent Application No. 20050206045.

DESCRIPTION

(9) This specification describes a special class of polyester polymers which have been discovered to have special advantages when used to make polyester bottles using the preform blow processes when the blowing fluid is incompressible or liquid. For example, the well known re-heat blow and injection blow and injection stretch blow processes described in U.S. Pat. No. 7,141,190, United States Patent Application 20050206045, and WO 2009/075791. All three of these documents are incorporated by reference in their entirety for the purpose of teaching the various processes which utilize a liquid to expand or blow the preform into the shape of a bottle.

(10) What has been discovered is that special class of polyesters show improvements in the above mentioned processes.

(11) Because the special class of polyesters having special advantages in the liquid blowing processes, the various attributes of the liquid blowing processes finding the special polyester polymers useful is reviewed below.

(12) It has also been found advantageous that these resins require much less pressure to blow the bottle using air rather than the traditional bottle grade polyesters

(13) The special class of polyester polymers are crystallizable. The term crystallizable means that the polyester polymer can become semi-crystalline, either through orientation or heat induced crystallinity. It is well known that no plastic is completely crystalline and that the crystalline forms are more accurately described as semi-crystalline. The term semi-crystalline is well known in the prior art and is meant to describe a polymer that exhibits X-ray patterns that have sharp features of crystalline regions and diffuse features characteristic of amorphous regions. It is also well known in the art that semi-crystalline should be distinguished from the pure crystalline and amorphous states.

(14) A useful polyester is a crystallizable polyester with more than 85% of its total moles of its acid moieties derived from terephthalic acid or its dimethyl ester wherein the total moles of the acid moieties are 100 mole %. Another useful polyester has more than 90% of its total moles of its acid moieties derived from terephthalic acid or its dimethyl ester, wherein the total moles of the acid moieties are 100 mole %.

(15) The crystallizable polyester will also have a primary comonomer content of at least 2% of the total moles of the acid plus glycol moieties derived from this primary comonomer. The primary comonomer has the functional groups connected by an non-cyclic structure containing more than two carbon atoms and it is preferably selected from the group consisting of the aliphatic diacids, aliphatic di-alcohols or their dimethyl esters. Saturated dimer acids (i.e. Pripol 1009F available from Croda International, PLC located in New Castle Del., USA), sebacic or adipic acid or their respective dimethyl ester are preferred primary comonomers.

(16) Primary glycol co-monomers examples are: polyoxyethylene glycols, Poly(tetramethylene ether)glycols, Polypropylene glycols; 1,6 hexanediol, long chain dimer diol (i.e. Pripol 2033 available from Croda International, PLC located in New Castle Del., USA). The primary comonomer acid or glycol moieties may also be mixture of diacids, di-alcohols or the respective dimethyl ester.

(17) The primary comonomer may also be branched such as isopropylene glycol.

(18) The comonomers of terephthalic acid derived moieties plus ethylene glycol derived moieties together should be present in the range of 90 to 99 mole percent of the total moles of acid plus total moles of glycol moieties, with 99 to 96 mole percent of the total acid plus glycol moieties being most preferred.

(19) The polyester polymer may contain other acid and glycol comonomer moieties, such as isophthalate derived from isophthalic acid or it dimethyl ester. In all cases, the total number of moles of acid moieties is 100% mole % of the moles of acid moieties and the total number of moles of glycol moieties is 100% of the moles of glycol moieties.

(20) Ethylene glycol is the glycol comonomer and should be present in at least 85% (mole %) of the total moles of glycol derived moieties in the polymer.

(21) The polyester polymer can be made using the traditional acid or ester melt polymerization processes and catalysts well known in the art. The melt process can be followed by the solid phase polymerization. In any event, the intrinsic viscosity of the polymer should be less than 0.95 dl/g and greater than 0.50 dl/g, with greater than 0.55 being more preferred, and greater than 0.60 dl/g being even more preferred. The preceding sentence is intended to set upper and lower limitations as well as define the possible ranges of 0.50 to 0.95 dl/g, 0.55 to 0.95 dl/g, and 0.60 to 0.95 dl/g.

(22) The polyester polymer can be further characterized by its melting temperature as determined by DSC at 10 C./min. The Tm (melting temperature) of the second heating should be in the range of 235 to 242 C., with 236 to 241 C. being more preferred with 237 to 240 C. being the most preferred.

(23) The polyester polymer can be further characterized by its glass transition temperature, as measured by DSC at 10 C./min on the second heating. The glass transition temperature or Tg, should be preferably in the range of 60 to 73 C., with 62 to 72 C. being more preferred with 63 to 71 C. being the most preferred.

(24) The primary comonomer and other monomers should be selected so as to keep the polyester polymer in the above specified characterization ranges.

(25) The polyester polymer exhibits a much lower energy to stretch meaning it should take much less energy to form the polymer into a shape. An example is forming a bottle from a preform injection molded of the crystallizable polyester polymer.

EXPERIMENTAL

(26) 2 batches of two polyester polymer formulations were made by melt polymerization followed by solid phase polymerization. These polymers had the following composition.

(27) Polyester Polymer 1's recipe was 93 mole % of terephthalic acid, 2 mole % of isophthalic acid and 5 mole % of adipic acid for 100 mole % of the total moles of acid moieties or 1 mole % and 2.5 mole % of the total moles of acid and glycol moieties. There was no glycol added other than ethylene glycol. The final product was analyzed for it moles of acid and glycol moieties yielding 93 mole % of terephthalate moieties derived from terephthalic acid, 2 mole % of isophthalate moieties derived from isophthalic acid and 5 mole % of adipate moieties derived from adipic acid for 100 mole % of the total moles of acid moieties and 97.3 mole % of ethylene glycol and 2.7 mole % of diethylene glycol. Those skilled in the art know that the diethylene glycol is a byproduct reaction and formed in situ.

(28) Polyester Polymer 2's recipe was 93 mole % of terephthalic acid, 2 mole % of isophthalic acid and 5 mole % of sebacic acid for 100 mole % of the total moles of acid moieties. There was no glycol added other than ethylene glycol. The final product was analyzed for it moles of acid and glycol moieties yielding 93 mole % of terephthalate moieties derived from terephthalic acid, 2 mole % of isophthalate moieties derived from isophthalic acid and 5 mole % of sebacate moieties derived from sebacic acid for 100 mole % of the total moles of acid moieties and 97.3 mole % of ethylene glycol moieties and 2.7 mole % of diethylene glycol moieties. Those skilled in the art know that the diethylene glycol is a byproduct reaction and formed in situ.

(29) Polymer 1 and Polymer 2 were characterized as follows:

(30) TABLE-US-00001 TABLE I Copolymer Polymer Formula 1 Polymer Formula 2 IV (dl/g) 0.826, 0.840 0.812, 0.794 0.767, 0.803 0.825, 0.771 COOH 8 12 1 8 (Carboxyl meq) L* 86.95 85.77 87.46 87.56 a* 2.17 2.07 1.93 1.37 b* 5.73 5.58 7.58 7.12 Tc_2.sup.nd ( C.) 138.89 141.25 136.47 135.96 Tg_2.sup.nd ( C.) 69.87 69.48 66.29 67.19 Tm_2.sup.nd ( C.) 238.84 238.11 237.92 238.4

(31) These polymers were used to injection mold a preform, placing the preform with a cavity of a mold and expanding the preform within the cavity of a mold by introducing an incompressible fluid, e.g. a liquid under pressure, into the preform located within the mold and stretching the preform to assume the shape of the surrounding mold cavity as described in the prior art processes incorporated into this specification. The liquid can be removed or remain in the blown container which is then sealed with the incompressible fluid remaining in the container. When the incompressible fluid remains in the container, the process is called simultaneous blow/fill as the blowing is actually filling the container with the contents to be packaged in the container.

(32) The comparative example using standard reference polyester resins failed as they produced crystalline bottles.

(33) These resins were also blown using compressed air and it was discovered that the pressure of the compressed air was at least 10% less than the amount used to blow a reference bottle of the same shape from a reference preform of the same preform geometry using a reference polyester control resin of 0.82 dl/g IV polyethylene terephthalate resin modified with approximately 2% IPA. (i.e. the reference polyester resin comprises 98 mole % of its acids are terephthalate moieties, 2 mole % of its acids are isophthalate units with the number of moles of acids totaling 100%. While made from 100 mole % ethylene glycol, the actual reference polyester will contain approximately 97.5 mole % ethylene glycol moieties and 2.5 mole % diethylene glycerol moieties made in situ as part of the process, with the number of moles of glycol moieties totaling 100 mole %.

(34) Thus there is a process for forming a bottle from the preform made using the resins above by placing the preform within a cavity of a mold and expanding the preform within the cavity of the mold by introducing a compressible fluid under a blow pressure into the preform located in the mold and stretching the preform to assume the shape of the surrounding mold cavity, wherein the blow pressure is at 10% less than the blow pressure used to stretch a reference preform into the same mold cavity, wherein the reference preform is made from a reference polyester. The reference preform is a preform of the same geometry as the preform made from the special polyesters except that the reference preform is made from a reference polyester which is 0.82 dl/g IV modified with approximately 2% IPA.

(35) Test Methods

(36) Intrinsic Viscosity

(37) The intrinsic viscosity of intermediate molecular weight and low crystalline poly(ethylene terephthalate) and related polymers which are soluble in 60/40 phenol/tetrachloroethane can be determined by dissolving 0.1 gms of polymer or ground pellet into 25 ml of 60/40 phenol/tetrachloroethane solution and determining the viscosity of the solution at 30 C.+/0.05 relative to the solvent at the same temperature using a Ubbelohde 1B viscometer. The intrinsic viscosity is calculated using the Billmeyer equation based upon the relative viscosity.

(38) The intrinsic viscosity of high molecular weight or highly crystalline poly(ethylene terephthalate) and related polymers which are not soluble in phenol/tetrachloroethane was determined by dissolving 0.1 gms of polymer or ground pellet into 25 ml of 50/50 trifluoroacetic Acid/Dichloromethane and determining the viscosity of the solution at 30 C.+/0.05 relative to the solvent at the same temperature using a Type OC Ubbelohde viscometer. The intrinsic viscosity is calculated using the Billmeyer equation and converted using a linear regression to obtain results which are consistent with those obtained using 60/40 phenol/tetrachloroethane solvent. The linear regression is
IV in 60/40 phenol/tetrachloroethane=0.8229IV in 50/50 trifluoroacetic Acid/Dichloromethane+0.0124
Hunter L*, a*, B*
The Color Measurement

(39) The measurements were taken on amorphous resin. A HunterLab ColorQUEST Sphere Spectrophotometer System, assorted specimen holders, and green, gray and white calibration tiles, and light trap was used. The HunterLab Spectrocolorimeter integrating sphere sensor is a color and appearance measurement instrument. Light from the lamp is diffused by the integrating sphere and passed either through (transmitted) or reflected (reflectance) off an object to a lens. The lens collects the light and directs it to a diffraction grating that disperses it into its component wave lengths. The dispersed light is reflected onto a silicon diode array. Signals from the diodes pass through an amplifier to a converter and are manipulated to produce the data. Spectral data is provided by the software.