|MIT KUDO TORI TAUS ON20170326842A1OLLA TAL VAI AI AI AIR ( 19) United States (12 ) Patent Application Publication (10 ) Pub. No. : US 2017/ 0326842 A1 MORITZ et al. ( 43 ) Pub . Date: Nov . 16 , 2017

(54 ) POLYESTER FILM INCORPORATING B650 25 / 14 (2006 . 01) SILICONE FOR RELEASE OF CANNED B32B 7 / 12 (2006 . 01) MEAT PRODUCTS ( 52 ) U . S. CI. CPC ...... B32B 15 / 09 ( 2013 .01 ) ; B65D 25/ 14 ( 71 ) Applicant: TORAY PLASTICS (AMERICA ) , (2013 .01 ) ; B32B 15 / 18 (2013 .01 ) ; B32B 7/ 12 INC ., North Kingstown, RI (US ) ( 2013 .01 ) ; B650 81/ 24 (2013 . 01 ); B65D 81 / 3415 ( 2013 .01 ) ; C08 ) 5 / 18 ( 2013 .01 ) ; (72 ) Inventors : Jan MORITZ , Bristol, RI (US ) ; Pat B32B 2307 / 748 (2013 . 01 ) ; B32B 2439 / 70 ANDREWS, West Kingstown, RI (US ) ; (2013 . 01 ) ; B32B 2307 /31 ( 2013 .01 ) ; C08J Keunsuk P . CHANG , North Kingstown , RI (US ) ; Christopher 2367 /02 (2013 . 01 ) ; CO8J 2483/ 04 (2013 . 01 ) NOTHNAGLE , Saunderstown, RI (US ) ; Stefanos SAKELLARIDES , East (57 ) ABSTRACT Greenwich , RI (US ) Embodiments herein relates to a Bisphenol A - free multi layer biaxially oriented polyester (BOPET ) film , for lami @( 73 ) Assignee : TORAY PLASTICS ( AMERICA ) , nation on metal sheets , which could be used for food INC . containers . The BOPET film has at least one outer release layer , which aids in the release of food , such as a high (21 ) Appl. No .: 15/ 663 , 142 protein food source , when food is cooked and sterilized in direct contact with the outer release layer . The BOPET film (22 ) Filed : Jul. 28 , 2017 can be laminated to metals used in the manufacture of food Related U .S . Application Data containers with the outer release layer being exposed to allow a direct food contact between the surface of the outer (63 ) Continuation - in -part of application No . 14 /954 , 390 , release layer and food . More particularly , the invention filed on Nov . 30 , 2015 . relates to a novel outer release layer resin composition comprising an ultra high molecular weight siloxane polymer Publication Classification and a polyethylene trephthalate resin ; and an alkali -metal (51 ) Int . CI. phosphate and a phosphoric acid compound added , during B32B 15 /09 ( 2006 .01 ) polymerization of the outer release layer resin composition , B32B 15 / 18 ( 2006 . 01 ) as a catalyst/ additive package to the ingredients forming the C08J 5 / 18 ( 2006 . 01 ) outer release layer resin composition . A wax component is B65D 81/ 24 ( 2006 .01 ) added in the outer release layer, for more robust release B650 81/ 34 ( 2006 .01 ) performance . Patent Application Publication Nov . 16 , 2017 Sheet 1 of 6 US 2017 /0326842 A1

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POLYESTER FILM INCORPORATING separation , discolouration , undesirable heat treatment taste SILICONE FOR RELEASE OF CANNED and loss of nutritional value ( destruction of vitamins and MEAT PRODUCTS protein components ) . [ 0008 ] In order to comply with the above aspects , a RELATED APPLICATIONS compromise has to be reached in order to keep the heat 10001 ] This present application is a continuation - in - part of sterilization intensive enough for the microbiological safety U . S . patent application Ser. No . 14 /954 ,390 filed on Nov. 30 , of the products and as moderate as possible for product 2015 , the entire content of which is hereby incorporated quality reasons . herein by reference in its entirety . Meat Products Suitable for Canning FIELD OF THE INVENTION [ 0009 ] Practically all processed meat products which [0002 ] This invention relates to Bisphenol A (“ BPA ” ) free require heat treatment during preparation for consumption multi - layer film , such as a biaxially oriented polyester are suitable for heat preservation . Meat products which do (BOPET ) film , for lamination on metal sheets , which could not receive any form of heat treatment before being con be used for food containers . More particulary, the multi sumed , such as dried meat, raw hams or dry sausages , are layer film has an outer release layer, which aids in the release naturally not suitable for canning as they are preserved by of food , such as a high protein food source , when food is low pH and/ or low water activity . cooked and sterilized in direct contact with the outer release [ 0010 ] The following , though not limiting , groups ofmeat layer . products are frequently manufactured as canned products : cooked hams or pork shoulders; sausages with brine of the BACKGROUND OF THE INVENTION frankfurter type ; sausage mix of the bologna or liver sausage type ; meat preparations such as corned beef, chopped pork ; Principles of Food Canning and ready -to - eat dishes with meat ingredients such as beef in gravy , chicken with rice , soups with meat ingredients such [ 0003 ] Unlike pasteurized " cooked ” meat products where as chicken soup or oxtail soup . the survival ofheat resistantmicroorganisms is accepted , the aim of sterilization ofmeat products is the destruction of all Can Linings contaminating bacteria including their spores. Heat treat ment of such products may be intensive enough to inacti [0011 ] Metal food and beverage containers , e. g. , cans, are vate /kill the most heat -resistant bacterial microorganisms, lined with a coating on the interior surface . This coating is which are the spores of Bacillus and Clostridium . In prac essential to prevent corrosion of the container and contami tice , the meat products filled in sealed containers are nation of food and beverages with dissolved metals . In exposed to temperatures above 100° C . in pressure cookers . addition , the coating helps to prevent canned foods from Temperatures above 100° C . , usually ranging from 110 - 130° becoming tainted or spoiled by bacterial contamination . The C . depending on the type of product, may be reached inside major types of interior coatings for food containers are made the product. Products are kept for a defined period of time from epoxy resins , which have achieved wide acceptance for at temperature levels required for the sterilization depending use as protective coatings because of their exceptional on type of product and size of container. combination of toughness, adhesion , formability and chemi 10004 ] If spores are not completely inactivated in canned cal resistance . Such coatings are essentially inert and have goods, vegetative microorganisms will grow from the spores been used for over 40 years . In addition to protecting as soon as conditions are favourable again . In the case of contents from spoilage , these coatings make it possible for heat- treated processed meat, favourable conditions will exist food products to maintain their quality and taste , while when the heat treatment is completed and the products are extending shelf life . stored under ambient temperatures . The surviving microor [0012 ] However , these epoxy polymers may contain a ganisms can either spoil preserved meat products or produce residual amount of a chemical building block called BPA , toxins which cause food poisoning of consumers , which has faced much scrutiny from consumer advocacy [0005 ] Amongst the two groups of spore -producing groups . Under Proposition 65 , California has proposed for microorganisms, Clostridium is more heat -resistant than the second time to list BPA as a cause of reproductive Bacillus . Temperatures of 110° C . will kill most Bacillus toxicity . Thus, there is a desire to eliminate BPA -based spores within a short time. In the case of Clostridium expoxy resins as protective coatings . temperatures of up to 121° C . are needed to kill the spores [0013 ] In the past decade , consumers and health experts within a relatively short time. have raised concerns about the use of BPA in food packag [0006 ] The above sterilization temperatures are needed for ing . The molecule has a shape similar to estrogens and thus short -term inactivation (within a few seconds ) of spores of may act as an endocrine disrupter. Bacillus or Clostridium . These spores can also be killed at [0014 ] Therefore , food companies are eager to move away slightly lower temperatures , but longer heat treatment peri from food packaging based on BPA . Coating manufacturers ods may be applied in such cases to arrive at the same level and their suppliers are working overtime to find a replace of heat treatment . ment for the ubiquitous epoxies, which are made by reacting 10007 ] From the microbial point of view , it would be ideal BPA with epichlorohydrin . In short , there is an urgent need to employ very intensive heat treatment which would elimi for a BPA - free coating for food containers . The BPA - free nate the risk of any surviving microorganisms. However, BOPET film of the present invention satisifes this need . most canned meat products cannot be submitted to such [0015 ] Laminating polyester films to metal prior to form intensive heat stress without suffering degradation of their ing the container parts is one solution for replacing contain sensory quality such as very soft texture, jelly and fat ers lined with an epoxy coating . Biaxially oriented polyeth US 2017 /0326842 A1 Nov . 16 , 2017 ylene terephthalate ( BOPET) films are used for multiple herein . In one embodiment, the silicone resin has a kine applications such as food packaging , decorative, and labels matic viscosity ranging from 10 - 50x100 centistokes at room for example . temperature . [ 0016 ] The food packaging industry uses BOPET films in many heat sealable tray applications where there might be BRIEF DESCRIPTION OF THE DRAWINGS direct contact of food to BOPET, but food release from the [ 0021 ] The patent or application file contains at least one BOPET film surface is inadequate . drawing executed in color. Copies of this patent or patent application publication with color drawing ( s ) will be pro vided by the Office upon request and payment of the Food Release necessary fee . [0017 ] One issue resulting from cooking & sterilization of [0022 FIG . 1 shows pictures of the different ingredients foods inside the container, especially for foods containing a used in preparing the food mix for Food Release Test . significant amount of solids such as of meat products , is [0023 ] FIG . 2 shows pictures of BOPET laminated metal adherence of solid food particles to the interior container disks and of a non - laminated BOPET film . surface , which makes discharging the entire can contents 10024 ]. FIG . 3 shows pictures of inserting of the food mix problematic . Various methods have been proposed in the into a jar that is sealed with cap having a BOPET laminated patent literature to address this phenomenon , which include metal disk , where the BOPET film contacts the food mix . incorporating a wax (U .S . Pat . No . 6 ,652 , 979 , U . S . Pat. No . [0025 ] FIG . 4 shows pictures ofmultiple sealed jars con 6 , 905 ,774 , U . S . Pat. No. 7 , 198 ,856 , U . S . Pat . No. 7 , 435 ,465 ) taining the food mix in a pressure cooker , and the pressure or a silicone compound ( U . S . Pat. No . 6 , 905 , 774) . cooker on a heated stove . [0026 ] FIG . 5 shows pictures showing removal of the SUMMARY OF THE INVENTION BOPET laminated metal disk from the cooked food mix . [0027 ] FIG . 6 shows pictures of BOPET laminated metal [ 0018 ] An embodiment herein relates to a polyester film disks demonstrating good and bad release of the cooked comprising at least one layer comprising : ( a ) 0 . 1 - 99 . 9 wt. % food mix from the BOPET film surface of the BOPET of a polyester resin P1 comprising an alkali metal phosphate laminated metal disks. in an amount of 1 . 3 mol/ ton of the polyester resin P1 to 3 . 0 [0028 ]. FIG . 7 shows pictures of a BOPET laminated metal mol/ ton of the polyester resin P1 , and phosphoric acid in an disk (“ Test Sample ” ) after the food release test with a grid amount of from 0 . 4 to 1 . 5 times by mole that of the alkali overlaid on the BOPET laminated metal disk to calculate the metal phosphate ; ( b ) 0 . 1 - 2 wt. % of a silicone resin com percentage of food area coverage where the cooked food prising a polydiemthylsiloxane resin ; ( c ) optionally 0 .001 to mix remains stuck to the BOPET film . 0 .09 wt. % of a wax component; and wherein the polyester [0029 ] FIG . 8 shows a plot of percentage of food area film is free of Bisphenol A . In one embodiment, the poly coverage where the cooked food mix remains stuck to the ester resin Pl comprises an aromatic polyester . In one BOPET film as a function of weight percent of the ultra high embodiment, the aromatic polyester comprises at least 50 molecular weight silicone . wt. % ethylene terephthalate as a constituent component of (0030 ) FIG . 9 shows a plot of relative crystallinity values the aromatic polyester . In one embodiment, the at least one ( counts per second ) determined by XRD ( X - ray diffraction layer comprises an outer release layer having a food area test )measured at different locations of the film of Compara coverage of about 10 % or less as measured according to tive Example 8 after steel lamination at the indicated lami Food Release Test. nation and post - bake temperature settings. [0019 ] In one embodiment, the film structure comprising [0031 ] FIG . 10 is a plot showing relative crystallinity at least an outer release layer A , further comprises a heat values ( counts per second ) determined by XRD ( X - ray sealable layer B comprising ( a ) 0 . 1 - 100 wt. % of a polyester diffraction test) measured at different locations of the film of resin P2 , wherein the polyester resin P2 is crystallizable and Example 7 after steel lamination at the indicated pre- heat different from the polyester resin P1 ; ( b ) 0 . 1 - 100 wt. % of an and post -heat temperature settings. amorphous copolyester resin or a polyester resin having a melting point of least 20° C . below that of the polyester resin DETAILED DESCRIPTION OF THE P2 ; and ( c ) 0 . 1 - 15 wt. % of an antiblock comprising organic INVENTION or inorganic particles. In one embodiment, the polyester film [0032 ] Embodiments herein relate to a polyester film , further comprises a heat- sealable layer C having the same or namely a BOPET film , which has superior heat resistance to substantially the same composition as that of the heat be able to withstand the temperatures associated with retort sealable layer B . In one embodiment, the polyester film sterilization temperatures and barrier properties to provide further comprises a heat -sealable layer C having a different corrosion resistance to a metal container by a food product. composition from that of the heat- sealable layer B . In one The BOPET film is capable of being laminated and formed embodiment, the polyester P2 comprises an aromatic poly to metal plates for the container forming process . Further ester. In one embodiment, the polyester resin P2 comprises more , the BOPET film is capable of providing a sufficient at least 50 wt. % ethylene terephthalate as a constituent release surface to enable high protein food (meat products ) component of the polyester resin P2. In one embodiment, to be easily removed from the container after high heat component ( b ) of the polyester resin having a melting point sterilization . Surprisingly the inventors have found that the of at least 20° C . below that of polyester resin P2 is release action imparted by incorporating silicone comprising essentially polybutylene terephthalate (PBT ) resin . ultra -high -molecular weight siloxane is greatly enhanced [0020 ] Another embodiment is related to a laminated when using a polyester resin carrier formulated with an metal sheet comprising a polyester film of the embodiments alkali metal phosphate and phosphoric acid during polym US 2017 /0326842 A1 Nov . 16 , 2017 erization . The original purpose of the alkalimetal phosphate ) [0038 ] Release layer A can further contain a wax compo phosphoric acid package was to improve hydrolysis resis nent for more robust release performance . The term “ wax tance and the added benefit of the enhancement of silicone ' s component” refers to a component containing a wax or release action was a surpising finding . wax - like material. Waxes are a diverse class of organic [0033 ] The BOPET film may comprise one ormore layers , compounds that are hydrophobic , malleable solids near preferably at least 2 layers. A multilayered BOPET film may ambient temperatures . They include higher alkanes and include one or more of each of : a container - side or inside lipids, typically with melting points above about 40° C . layer ( i .e ., heat seal or metal bonding layer ), a food or ( 104° F . ) , melting to give low viscosity liquids . Waxes are outside layer, a food release layer. In addition there may be insoluble in water but soluble in organic , nonpolar solvents . one or more core layers between the layer bonded to the Natural waxes of different types are produced by plants and metal surface and the food side layer that is in direct contact animals and occur in petroleum ( source : https : / / en .wikipe dia .org /wiki / Wax ) . A “ wax - like material” refers to a mateial with the food stored inside the container. BOPET Film that has properties of a wax but is not a wax . [0034 ] The film which can be laminated to a metal plate [0039 ] The amount of wax component adeded is is 0 . 001 for canning which is typically made of tin -free steel ( TFS ), to 0 . 090 wt. % . Examples of such waxes are mentioned in electro - tin - plated steel (ETP ) , or aluminum , said film char U . S . Pat. No. 6 , 905 ,774 , incorporated herein by reference in acterized by a dimensional change of not more than 2 . 0 % its entirety . Specifically , examples of the wax compounds after a heat treatment of 210° C . as part of the continuous which can be used here , are the esters of aliphatic carboxylic lamination process . acid compounds and aliphatic alcohol compounds, and the [0035 ]. The films disclosed herein include two - layer or amides of aliphatic carboxylic acid compounds and aliphatic three -layer coextruded and biaxially drawn structures . The amine compounds, and preferably the wax is composed of a outer release layer and an optional lower " skin " layer are compound in which the total number of carbons is 30 to 120 , generally thinner than the core “ main ” layer . The outer and more preferably 40 to 100 . As examples of such release layer (thereafter referred to as “ skin A " ) , typically compounds, synthetic or natural waxes comprising aliphatic contains an ultra high molecular weight silicone (based on esters like stearyl stearate , carnauba wax , candelilla wax , siloxane ) resin , that has been pre -blended with a copolyester rice wax , pentaerythritol full ester, behenyl behenate, palmi elastomer resin to form a “ masterbatch , ” which is then added tyl myristate and stearyl triglyceride , are preferred from the at low levels in the outer release layer during coextrusion . point of view of compatibility with the polyester. [0036 ] The term “ ultra high molecular weight silicone ” or [0040 ] In particular, from the point of view of outstanding “ UHMW PDMS” (where PDMS stands for polydiemthyl release properties following repeated use , use after fabrica siloxane ) refers to PDMS resins , wherein the UHMW tion and use in an aqueous environment, and from the point PDMS has kinematic viscosities ranging from 10 - 50x100 of view of manifesting non - adsorption properties and centistokes at room temperature. ( G . Shearer ; Silicones in enhancing hygiene in food packaging applications , etc , the the Plastics Industry , article 15 published in chapter 2 : addition of carnauba wax is preferred and especially refined " Silicones in Industrial Applications” , in Inorganic Poly carnauba wax . mers , edited by Roger de Jaeger, Nova Science Publishers , 10041 ] The term “ robust perfomance ” relates in particular 2007 ) . According to the above cited reference , an advantage to commercial metal lamination installations, where , due to of UHMW PDMS is that it forms stable droplet domains in process limitations, there is a variability across the web various thermoplastic carriers as pellets , so as to allow easy width , in terms of heat history, and , correspondingly , in addition of the additive directly to the thermoplastic during terms of the final morphology of the laminated film . Such an processing . Another advantage of UHMW PDMS is that it installation is described in U . S . Pat. No. 9 , 358 , 766 . A does not bleed - out from the BOPET while at the same time commercialmetal lamination line has two key factors affect migrates to the surface of the BOPET film , thereby provid ing such morphology : one is the preheat temperature of the ing desirable release charatceristics. steel sheet just prior to coming in contact with the polyester [ 0037 ] The typical UHMW silicone concentration in the film at the point of lamination ( a pair of nip rolls one or both masterbatch is 50 wt. % . Masterbatch addition levels in the of which are also heated ) . For biaxially - oriented PET- based outer release layer range between 0 . 2 and 4 wt. % , resulting film this temperature is between 320 - 430° F ., preferably in net siloxane content in the range 0 . 1 - 2 % . The remaining 360 - 430° F . The second is the temperature setting at the components of the outer release layer are polyethylene post- heat station ( for example an infrared (IR ) -heated oven ) , terephthalate ( PET ) resin composition comprising an alkali which serves to stabilize the initial bond between the plastic metal phosphate as a phosphorus compound in an amount of film and the steel created during the lamination step . For 1 . 3 mol/ ton to 3 . 0 mol/ ton , and phosphoric acid as another biaxially -oriented PET- based film this temperature is phosphorus compound in an amount of 0 . 4 to 1 .5 times (by between 350 - 500° F . , preferably 420 - 460° F . As the lami mole ) that of the alkali metal phosphate . (major component) , nated sheet exits the post- treatment ( post -bake ” station , the and optionally inorganic particles for anti- blocking pur variability in the morphology of the laminated polyester film poses. Typical inorganic particle compositions in this case is is manifested for example by the crystallinity ( determined silica ( silicon dioxide, SiO ) in sizes ranging from sub for example by X -ray difraction — XRD ) at different spots micron up to a few microns . The silica particles are typically across the laminate width ; that crystallinity is also affected added during coextrusion in the form of a concentrate PET by both the preheat temperature and the post -heat tempera chip (“ silica masterchip ” ) made by adding silica in the ture . The profiles of the relative crystallinity values ( counts polymerization . Typical silica content in the silica master per second ) , determined by XRD for a film not containing chip is 1 - 3 wt. % ; typical addition level of the silica wax is shown in FIG . 9 and for a film containing wax is masterchip in the outer release layer is 1 - 15 wt % , resulting shown in FIG . 10 . It was surpisingly found , as shown in FIG . in net silica content around 0 . 1 - 3 wt. % . 10 , that the addition of wax allows the relative crystallinity US 2017 /0326842 A1 Nov . 16 , 2017 values (counts per second ) , determined by XRD ( X -ray facilitate easier adhesion to metal during thermal lamination . diffraction test ) measured at different locations of the film However the addition of such a copolymer is not necessary after steel lamination at a given lamination and post- bake for making the metal contact layer heat -sealable , as the temperature settings is lower than that of the film of FIG . 9 temperature of lamination and subsequent oven treatment containing no wax . It was also suprisingly found that the can be adjusted to a value that makes the metal- contact side film of FIG . 10 had better food release than the film of FIG . tacky enough to bond to the metal. Whereas PET polyester 9 . When combined with the siloxane and the PET Resin P1 has a melting point peak around 250° C ., melting initiation ( PET resin comprising alkali metal phosphate and phos occurs at around 205º C . ( 400 F ) , which is consistent with phoric acid ), the amount of wax required for meat release is lamination temperature conditions and facilitates initial lower than that present in a film which uses solely wax for bonding at the pressure of the lamination nip rolls , which is release properties (such as LumirrorTM grade FN8 polyester further strengthened by oven treatment of the laminated film from Toray Industries. That film is impregnated with structure at around 460° F . carnauba wax compounded at a level in the range prescribed by U . S . Pat . No . 6 ,652 ,979 ( 0 . 1 - 2 wt. % ) or U . S . Pat . No . Polyester Resin Composition 6 , 905, 774 ( 0 . 1- 5 wt. % ). ) . [ 0046 ] The resin in layer A is a polyester resin , “ P1” , [0042 ] The remaining two layers will be hereafter named comprising a buffer soluble in ethylene glycol, and contain layer “ B ” for the core layer and skin layer “ C ” for the skin ing a substance exhibiting ion dissociation . Such a buffer layer lying on the opposite side versus the A skin layer . agent is preferably an alkali metal salt , e . g ., salts of phthalic Thickness distribution ranges between 5 - 30 % , 40 - 95 % , and acid , citric acid , carbonic acid , lactic acid , tartaric acid , 0 - 30 % for layers A , B , and C respectively , based on overall phosphoric acid , phosphorous acid , hypophosphorous acid ; film thickness . Typical total film thickness after biaxial alkali metal salt of polyacrylic acid compound or the like . stretching is 10 - 25 microns, preferably 12 microns- 23 More particularly , the alkali metal is potassium or sodium , microns. therefore specific alkali metal salt examples such as sodium 10043 ] The two - layer or three - layer film structure is lami dihydrogen hydroxycitrate , potassium citrate , potassium nated onto a metal sheet (steel or aluminum ) which is then hydrogen hydroxycitrate , sodium carbonate , sodium tartrate , formed into a container. Both sides of the metal sheet may potassium tartrate , sodium lactate , sodium carbonate , be laminated with plastic film but the films of this invention sodium hydrogen phosphate , potassium hydrogen phos are intended for lamination on the metal sheet side that is phate , potassium phosphate , sodium dihydrogen phosphate , intended to become the inside surface of the container and sodium hypophosphite , sodium hypochlorite , sodium poly in such a way that the outer release layer containing the acrylate, etc . can be cited . silicone is the food - contact layer ( i . e . the layer away from [0047 ] In the preferred embodiment, P1 is a polyester the metal substrate of the can ) . resin composition comprising an alkali metal phosphate as a 100441 Core layer B may include 100 wt % PET resin first phosphorus compound in an amount of 1 . 3 mol/ ton to (“ base resin ” ) . If there is no C layer , then layer B may also 3 . 0 mol/ ton of polyester resin , and phosphoric acid as a contain anti -block - containing masterbatches or low -melt second phosphorus compound in an amount of 0 .4 to 1 . 5 ing - temperature copolyesters , described below in more times ( by mole ) that of the alkali metal phosphate . It is detail for optional layer C . preferable for the polyester resin composition that its acid [0045 ] Optional skin layer C can be a lower - temperature component contains a dicarboxylic acid component in a melting ( vs. crystalline PET ) or amorphous polyester copo molar amount of 95 % or more . In particular, a terephthalic lymer or a blend of PET base resin with a lower melting ( or acid component is preferred in view of the mechanical amorphous ) polyester copolymer. One example of a lower characteristics . It is also preferable , from the viewpoint of melting polyester are resins comprising butylene terephtha mechanical characteristics and thermal characteristics, that late repeat units such as poly (butylene terephthalate ) the glycol component contains a straight- chain alkylene ( “ PBT” ) resin and copolymers thereof with other dicarbox glycol having 2 to 4 carbon atoms in an amount of 95 % by ylic acids or diols , such as isophthalic acid , naphthalene mole or more . dicarboxylic acid , azelaic acid , sebacic acid , adipic acid , [0048 ] In particular, ethylene glycol, which has two car ethylene glycol, 1 , 3 -propanediol , 1 - 2 propanediol, neopen bon atoms, is preferred from the point of view of moldability tyl glycol, 1 , 4 - cyclohexyldimethanol, and the like . A non and crystallization of the polyester resin . In adition to the exhaustive list of suitable examples of polybutylene terephthalic acid and ethylene glycol additional polyester terephthalate (PBT ) resins can be: Crastin® FG6129 , Cras raw materials , e . g . diacids such as isophthalic acid , naph tin® FG6130 from Dupont, Celanese 1600 , Celanex® 1700 thalene dicarboxylic acid or diols such as 1 , 4 - cyclohex from Ticona , TorayconTM 1100M , TorayconTM 1200M from yldimethanol, diethylene glycol, 1 , 3 - prolylene glycol, 1 , 4 Toray Industries , etc . Another example of lower melting butylene glycol, may be present in the polyester composition polyester are resins comprising trimethylene terephthalate polymerization mix as copolymerized components at levels repeat units such as poly ( trimethylene terephthalate ) (PTT ) up to 5 mole % of the total diacid or diol . When the contents resins and copolymers thereof with other dicarboxylic acids of a copolymerized component exceeds 5 % molar , this will or diols such as isophthalic acid , naphthalene dicarboxylic cause a decrease in heat resistance due to the decrease of the acid , azelaic acid , sebacic acid , adipic acid , ethylene glycol, melting point and will also cause a reduction in the hydro 1, 4 -butanediol , 1 -2 propanediol, neopentyl glycol , 1, 4 - cy lytic resistance due to the decrease in the polyester degree of clohexyldimethanol, and the like. A non -exhaustive list of crystallization . It is preferable, from the viewpoint of the suitable examples of polytrimethylene terephthalate (PTT ) hydrolytic resistance , that the polyester resin composition resins can be : Sorona® (DuPont ) , Corterra® ( Shell ) , contains an alkali metal phosphate in an amount of 1 . 3 Ecoriex® (SK Chemicals ) . The purpose of adding the lower mol/ ton to 3 . 0 mol/ ton of polyester resin . It is preferably 1 . 5 melting or amorphous polyester copolymer in that layer is to mol/ ton to 2 . 0 moles/ ton of polyester resin . When the US 2017 /0326842 A1 Nov . 16 , 2017 content of the alkali metal phosphate is less than 1 . 3 mol/ ton are alkali metal elements . The elements Mg, Ca , Mn , and of polyester resin , long term hydrolysis resistance may be Co , which are divalent metal elements , are transesterifica insufficient. On the other hand , when the alkali metal phos tion catalyst and confer electrostatic characteristics such as phate is contained in an amount exceeding 3 . 0 mol/ ton of the resistivity of the polyester resin . Sb , Ti and Ge are metal polyester resin , this is likely to cause phase separation members having an ability to catalyze the polymerization of (precipitation ) of the alkali metal phosphate . the polyester resin and serve as polymerization catalyst . [0049 ] Examples of alkali metal phosphate include sodium dihydrogen phosphate , disodium hydrogen phos BOPET Film Process phate , trisodium phosphate , potassium dihydrogen phos [0054 ] Preferably the multi - layer PET film is biaxially phate , dipotassium hydrogen phosphate , tripotassium phos oriented prior to laminating it to the metal substrate . Typi phate , lithium dihydrogen phosphate , dilithium hydrogen cally , a raw material PET resin is supplied in solid form to phosphate , trilithium phosphate . a melt processing device , preferably a continuous screw [0050 ] Preferred examples of alkali metal phosphate are extruder . The heating of the melt processor is controlled to alkali metal dihydrogen phosphates and alkali metal phos maintain the PET resin above its melting point but below phates . Alkali metal phosphates in which an alkali metal is polymer degradation temperature . PET molten resin is Na or K are preferred from the viewpoint of long - term extruded from an appropriately shaped die to form a thin , flat hydrolysis resistance . Particularly preferred examples of ribbon of polymer melt . The polymer ribbon is quenched in alkali metal phosphate are sodium dihydrogen phosphate air and or on a chilled roll to form a solid , self - supporting and potassium dihydrogen phosphate . It is preferable from film . The film is taken up by sets of rollers turning at the viewpoint of long - term hydrolytic resistance that the different rotation speeds that stretch the film in the direction phosphoric acid is 0 . 4 to 1 . 5 times that of the alkali metal of continuous forward motion , referred to as the machine phosphate in a molar ratio . It is preferably from 0 . 8 to 1 .4 direction (“ MD ” ) . The stretching can be accompanied by times . If it is smaller than 0 . 4 times , long -term hydrolysis heating of the film to establish crystal orientation in the MD . resistance may deteriorate . If it exceeds 1 . 5 times , a polym The mono - directionally oriented film is clamped at its erization catalyst is deactivated by excess phosphoric acid ; opposite edges in and stretched in the transverse machine this will result in a delay of the polymerization , as well as direction ( “ TD ” ) laterally perpendicular to the MD in a increases in the amount of terminal groups COOH , which tenter oven . The tenter oven is heated to temperatures will contribute to degrading the hydrolytic resistance of the operative to establish crystal orientation in the TD thus polyester resin . forming a biaxially oriented PET film . Preferably biaxially [0051 ] According to the calculations based on the contents oriented PET film is stretched about 100 % - 400 % in the MD of alkali metal phosphate and phosphoric acid , the polyester and 100 % - 600 % in the TD . The biaxially oriented film can resin composition contains an alkali metal element in an be heat- set at temperatures preferably between about 300° F . amount of 1 . 3 mol/ ton of polyester resin to 9 . 0 mol/ ton of and about 490° F . , more preferably about 350° F. to about polyester resin and a phosphorus in an amount of 1 . 8 mol/ ton of polyester resin to 7 . 5 mol/ ton of polyester resin . 460° F . In view of the type of alkali metal phosphate preferred , the EXAMPLES polyester resin composition preferably contains an alkali metal element in an amount of 1 . 3 mol/ ton of polyester resin [0055 ] This invention will be better understood with ref to 6 . 0 mol/ ton of polyester resin and a phosphorus in an erence to the following Examples , which are intended to amount of 1 . 8 mol/ ton of polyester resin to 7 . 5 mol/ ton of illustrate specific embodiments within the overall scope of polyester resin . the invention , but the scope of the invention is not limited to [ 0052] From the viewpoint of reducing the amount of the Examples. terminal groups COOH and inhibiting the formation of foreign bodies, it is preferable that the total content of Resin Materials phosphorus compounds contained in the polyester resin composition of the present composition is from 30 PPM to [ 0056 ] Resin materials for films mentioned in the 150 PPM by weight of the polyester resin composition , in examples were as follows: terms of the amount of phosphorus element. It is more [0057 ] PET Resin P1 (PET resin comprising alkali metal preferred that this content is 60 PPM to 150 PPM . phosphate and phosphoric acid ) : Toray F1CCS64 ( IV = 0 .65 ; [0053 ] It is preferable that the composition of polyester Tm = 255° C .) supplied by Toray Films Europe. resin Plcomprises a metal - containing compound (“ metal [0058 ] PET Resin P2 ( ordinary film - grade PET resin , not compound ” ) of which the metal element is at least one comprising alkali metal phosphate ): Toray F21MP (IV = 0 . member selected from the group consisting of Na , Li and K , 65 ; Tm = 255° C . ) manufactured by Toray Plastics America . a metal compound of which the metal element is at least one [0059 ] PET Resin P3 : Bottle - grade PET resin 8712A from member selected from the group consisting of Mg , Ca , Mn , Invista with an IV of 0 .75 . and Co , and a metal compound, the metal element is at least [0060 ] PET Resin P4 : PET Resin anti- block masterbatch onemember selected from the group consisting of Sb , Ti and type F18M , containing 2 % silica particles of average size 2 Ge, and the total amount of these metal elements is adjusted um ( Fuji Silysia 310P ) manufactured by Toray Plastics to 30 PPM or more and 500 PPM or less based on the entire America (IV = 0 .62 ; Tm = 255º C . ) . of the polyester resin composition . By adjusting the total [0061 ] Amorphous Copolyester Resin CoP1 : Eastar® amount of metal elements within this range , the amount of 6763 PETG supplied by Eastman Chemical (based on terminal groups COOH can be reduced in the polyester resin terephthalic acid reacted with 33 :67 molar parts combination to improve its heat resistance . It is more preferred that this of CHDM ( 1 ,4 - cyclohexyldimethanol) / ethyelneglycol) ) ; content is 40 PPM to 300 PPM . The elements Na, Li and Ka IV = 0 . 76 . US 2017 /0326842 A1 Nov . 16 , 2017

[0062 ] Slow - crystallizing Copolyester Resin COP2 : IPET Test Methods F55M Resin (IV = 0 .69 ; Tm = 205° C . ) manufactured by Toray [0071 ] The various properties in the above examples were Plastics America based on 19 :81 molar (= weight in this measured by the following methods: case ) parts combination of isophthalic /terephthalic acid [0072 ] Intrinsic viscosity ( IV ) of the film and resin were reacted with ethylene glycol. tested according to ASTM D 4603 . This test method is for [0063 ] Silicone Resin Masterbatch : Dow Corning MB50 the IV determination of poly ( ethylene terephthalate ) (PET ) 010 containing 50 % of an ultra - high molecular weight soluble at 0 .50 % concentration in a 60/ 40 ratio of phenol / polymerized siloxane (“ Silicone Resin ” ) and 50 % of a 1 , 1 , 2 , 2 -tetrachloroethane solution by means of a glass cap polyester elastomer carrier resin . illary viscometer . [ 0064 ] Low -melting point polyester resin P5 : Polybuty [0073 ] Melting point of copolyester resin is measured lene terephthalate (PBT ) resin Crastin® FG6130 from E . I . using a TA Instruments Differential Scanning calorimeter DuPont De Nemours , having melting point 223° C . model 2920 . A 0 . 007 g resin sample is tested , substantially [ 0065 ] The Carnauba wax component was added in the in accordance to ASTM D3418 -03 . The preliminary thermal form of of a masterbatch ( “ Wax MB ” ) containing 2 wt. % cycle is not used , consistent with Note 6 of the ASTM Standard . The sample is then heated up to 300° C . tempera wax , available under the trade name W030 from Toray ture at a rate of 10° C . /minute , while heat flow and tem Industries . perature data are recorded . The melting point is reported as the temperature at the endothermic peak . General Film Making Procedure 10074 ] Film crystallinity were measured by X - Ray Dif [0066 ] The multi- layer coextruded BOPET film was made fraction method on a PANalytical X 'Pert PRO system with using a 1 .5m - wide pilot- line sequential orientation process Cu X -Ray source ( 40 kV, 20 mA ) and a Xe gas proportional The coextruded film is cast onto a chill drum using an type detector. The incident X - ray beam is directed at the electrostatic pinner , oriented in the machine direction sample over a spectrum of angles and the intensity of the through a series of heated and differentially sped rolls , diffracted beam is measured at each angle as the count of the followed by transverse direction stretching in a tenter oven . number of pulses per second . A measure of crystallinity [0067 ] The multilayer coextruded laminate sheet is coex specified as “ Counts per Second ” ( cps ) is reported based on truded by means of a main extruder for melting and con the count of the number of pulses at peak intensity of the veying the core blend to the die and by means of one or two diffracted beam . The sample was scanned from 18° to 32° to sub - extruders for melting and conveying the skin blends to cover both PBT and PET maximum diffraction angles , the die . Extrusion through the main extruder takes place at 20 = 23 .38° and 20 = 25. 8° for the [ 100 ] crystallographic plane processing temperatures of ca . 270° to 285° C . Extrusion (angles of peak intensity ) . Preferred cps values before lami through the sub - extruders takes place at processing tempera nation are 1500 or higher and after lamination 900 or higher. tures of ca . 270° C . to 280° C . Both the main and the sub polymer melt streams flow through a die to form the Food Release Test: laminate coextruded structure and is cast onto a cooling [0075 ] The food area coverage on the food contact side of drum whose surface temperature is controlled at about 21° the polyester film laminated to steel is measured according C . to solidify the non -oriented laminate sheet at a casting to a food release test , referred herein as “ Food Release Test. ” speed of about 9 mpm . The non - oriented laminate sheet is The procedure of the Food Release Test is descibed below . stretched in the longitudinal direction at about 75° C . to 850 [0076 ] A food mixture of chicken egg / ground beef/ flour at C . at a stretching ratio of about 3 times the original length a ratio of 3 / 2 / 1 was prepared , as follows: and the resulting stretched sheet is annealed at about 70° C . A . Food Release Mix Preparation Steps shown in FIG . 1 to obtain a uniaxially oriented laminate sheet. [0077 ] For 8 -10 jar test : 1 lb of ground beef was put in [ 0068 ] The uniaxially oriented laminate sheet is intro the mix container, such as a plastic jar duced into a tenter at a line speed of ca . 27 mpm and [0078 ] The contents of five Grade A large chicken eggs preliminarily heated at 80° C ., and stretched in the trans was added into the mix container and mixed manually verse direction at about 90° C . at a stretching ratio of about with a paddle or a metal rod 4 times the original width and then heat - set or annealed at [0079 ] 8 oz of all -purpose white flour was added slowly about 210° C . to reduce internal stresses due to the orien while mixing , until the mixing was thorough tation and minimize shrinkage and give a relatively ther B . Placing samples in glass test jars as shown in FIGS. 2 and mally stable biaxially oriented sheet . [0080 ] Disks were cut out using shears from the film / Film Thermal Lamination Procedure onto Metal Sheet metal laminates described above, small enough to fit [0069 ] Tin - free steel ( TFS ) with a thickness of 0 .0075 " the bottom of the jar ( FIG . 2 ) : In the Examples , 47 mm was preheated to 400 F ( except where otherwise indicated ) . diameter disks were used to fit inside half- pint wide The steel and film were passed through a set of nipped rolls mouth Ball® jars forming the initial bond of film to steel . The film and steel 10081] BOPET film was cut to sheet sizes large enough laminate structure were then passed through a secondary to fit in the jar and hold the food mix as decribed in the heating operation ( post -bake ” ) at 460 F for 20 seconds, following steps then cooled to room temperature . 10082 ] A sheet of film was placed on top of the jar can [ 0070 ] The film side laminated to steel was the side (meat release side up ) and then the metal disk on top of opposite that of the silicone - comprising side ( food contact it, with the food contact side facing upward side ; side A in the examples ) , i . e . the lamination side was 10083 ] A couple of soup spoon - size scoops of the food side B or C in the examples . release mix were placed on top of the sample disk US 2017 /0326842 A1 Nov . 16 , 2017

[ 0084 ] The film was wrapped around the food release tions ( f) , ( g ) , ( h ) . The testing consists of exposing the mix and the disk sitting underneath the food release food - contact surface (layer A in this case ) under the follow mix . ing specifications for each of the conditions of use , and then [0085 ] The wrapped food mix ( including the sample determining the levels of choloroform - soluble extractives disk at the bottom ) was inserted into the jar and the jar present in the exposure medium : closure was applied . [0102 ] Condition ( f ) : Allowed for food excluding alco holic beveages at temperures not to exclude 250° F . — Ex C . Retorting and Testing (FIGS . 4 and 5 ) tractables Limit : 0 . 5 mg/ in ? after 2 - hr exposure in n - heptane [0086 ] The “ retort ” ( a pressure cooker as shown in FIG . at 150° F . , and distilled water at 250° F . 4 ) was filled with water up to 0 . 5 " below the underside [0103 ] Condition ( g ): Allowed for alcoholic beverages not of the perforated steam plate exceeding 50 % alcohol - Extractables Limit : 0 .5 mg/ in ? [0087 ] The test jars were placed on top of the plate and after 24 - hr exposure in 50 % ethanol at 120° F . retort ( pressure cooker ) cover was applied securely . [0104 ] Condition ( h ) : Allowed for containing foods during [0088 ] The retort was placed on a hot plate set to baking or oven cooking at temperatures exceeding 250° F . medium -high and retorted for 90 minutes after the Extractables Limit : 0 . 02 mg/ in ? after 2 - hr exposure in n - hep pressure valve started oscillating ( inside pressure 14 .7 tane at 150° F . psig , temperature around 260° F .) . Examples 1 and la [0089 ] Pressure cooker was removed from heat and allowed to cool until the valve came down , signifying [0105 ] 3 - layer BOPET film structures were produced by it is safe to open . melt extrusion from three extruders supplying the resin [0090 ] Pressure cooker was opened , jars removed with blends corresponding to layers A , B , and C as shown on tongs and were let to rest overnight Tables 1 , 2 , and 3 respectively . The silicone masterbatch [0091 ] Film was unwrapped from the food mix (the content in layer A was 0 . 5 % , corresponding to silicone food mix was still attached to the metal disk ) . content 0 . 25 wt. % . The differences between compositions 1 10092 ] Disk was peeled away from the food mix in an and la were with respect to the antiblock masterbatch ( P4 ) orthogonal motion and evaluated for release perfor content in layer A and with respect to the amorphous mance . See FIG . 6 for good and bad examples of food copolyester (COP1 ) content in layer C ( and the resulting release . differences in the content of the majority resin balance P1 10093 ] “ Retort process” means a procedure in which the and P2 in layers A and C repsectively ). The cast film was inside or outside of a metal container with a wall composed formed into a biaxially oriented film by stretching 3 times of a composite of a metal substrate having a polymer film along the machine direction at a temperature of 82° C . and laminated onto the inside , the outside or both sides of the subsequently stretching 4 times along the transverse direc substrate is treated with live steam or super -heated water for tion through an oven held at a temperature 85 - 93° C . in the a period of time. stretch zone and 204° C . in the anneal zone and collected in [0094 ] “ Live steam ” means that steam directly contacts roll form by means of a rotating winder at a linear speed of the surface of the container. The steam is usually super 32 m /min . heated , i . e . , above the boiling point of water. A nominal [0106 ] The films were subsequently laminated on a sheet retort process calls for exposure to steam at temperature of of tin - free metal sheet with side C adhering onto the metal 260° F . for 90 minutes. The temperature and duration of sheet surface Film A side was then tested for food release exposure of the retort process can vary to provide an according to the procedure described earlier . The score , approximately equivalent sterilization and food pasteuriza expressed as percentage of total area occupied by food tion effectiveness . For example , the temperature might be remains is listed in Table 4 higher for a shorter duration or lower for a longer duration . [ 0095 ] The release performance was rated by producing a Examples 2 and 2a photographic image of the test laminated disk after release [0107 ] Examples 1 and la were repeated with the only and superposing a rectangular grid image using Microsoft major difference being that the silicone masterbatch content PaintTM software . The number of grid squares occupied by in layer A was 1 . 0 % , corresponding to silicone content 0 . 5 food remained adhering was then counted and expressed as wt. % . using an A / B /C three -layer structure as shown in percentage of the total number of grid squares . The lower the Tables 1 , 2 , 3 respectively . The Results of the food release test percentage the better the food release performance (FIG . 7 ). are listed in Table 4 The acceptance rating , based on percentage , is as follows : ( based on U . S . Pat. No. 6 ,905 , 774 ) Example 3 [0096 ] Grade A (“ Excellent” ) : 0 - 5 % [0108 ] Example 1 was repeated with the only major dif [0097 ] Grade B (“ Good ” ) : 5 - 10 % ference being that the silicone masterbatch content in layer [0098 ] Grade C (“ Acceptable ” ) : 10 - 20 % A was 2 .0 % , corresponding to silicone content 1 . 0 wt. % . [0099 ] Grade D (“ Poor ” ) : 20 -50 % making an A / B / C three - layer structure as shown in Tables [0100 ] Grade E (“ Very Poor” ) : 50 -100 % 1 , 2 , 3 respectively . The Results of the food release test are Food Migration Test listed in Table 4 [ 0101 ] Testing was conducted by a qualified laboratory Example 4 (named at the time of testing as follows : : Covance Labora 01091 A 2 - layer BOPET film structures was produced by tories, Madison , Wis . ) ) under the conditions prescribed by melt extrusion from two extruders supplying the resin blends Code of Federal Regulations , Title 21CFR 177 . 1630 , condi- corresponding to layers A and B as shown in Tables 1 , 2 , US 2017 /0326842 A1 Nov . 16 , 2017

respectively . Layer B contains 15 % PBT. The extrusion temperature 85 - 93° C . in the stretch zone and 204° C . in the conditions were the same as those listed in Comparative anneal zone , and collected in roll form by means of a Example 5 . The silicone masterbatch content in layer A was rotating winder at a linear speed of 32 m /min . The final A / B 0 .5 % , corresponding to silicone content 0. 25 wt. % . biaxially -oriented two - layer structure is shown in Tables 1 and 2 respectively . Like Example 3 , this Comparative Example 5 Example comprised 2 . 0 wt % of silicone masterbatch in [0110 ] Example 4 was repeated with the only difference layer A , corresponding to silicone content 1 wt. % The being that the weight ratio of PBT in layer B was increased results of the food release test are listed in Table 4 . to 30 % . Example 6 Comparative Example 6 [0111 ] Example 5 was repeated with the only difference [0117 ] Comparative Example 5 was repeated with the only being that the weight ratio of PBT in layer B was increased difference being that the silicone masterbatch content in to 45 % . layer A was 4 .0 wt % , corresponding to silicone content 2 . 0 wt. % , making an A / B two -layer structure as shown in Comparative Example 1 Tables 1 and 2 respectively . The results of the food release [ 0112 ] Example la was repeated with the only major test are listed in Table 4 difference being that no silicone masterbatch was added in layer A , making an A / B /C three -layer structure as shown in Comparative Example 7 Tables 1 , 2 , 3 respectively . The results of the food release test are listed in Table 4 [0118 ] Comparative Example 3 was repeated ( 0 .5 wt. % siliconemasterbatch in the A layer corresponding to 0 .25 wt. Comparative Example 2 % silicone ) with the only difference being that the major [0113 ] For this comparative example a twolayer (layers A resin in layer A was P3, making an A / B / C three - layer and B being identical other than the fact that layer B contains structure as shown in Tables 1 and 2 respectively . The results internal recycle ) commercial biaxial film , available from of the food release test are listed in Table 4 Toray Plastics America grade “ LumirrorTM 48G PA66 " was utilized . That film product is based on P2 as base resin and REFERENCE EXAMPLE P4 as antiblock masterbatch respectively . The AB structure is shown in Tables 1 and 2 and the results of the food release [0119 ] The reference example is represented by a com test are listed in Table 4 mercial film currently being considered suitable for internal container liner with food release properties , namely Lumir Comparative Example 3 rorTM grade FN8 polyester film from Toray Industries . That [0114 ] Example la was repeated with the only difference film is impregnated with carnauba wax compounded at a that the major polyester resin (base resin ) was P2 (standard lelevel in the range prescribed by U . S . Pat . No . 6 ,652 , 979 film - grade PET ) and no PET resin comprising alkali metal ( 0 . 1 - 2 wt. % ) or U . S . Pat. No. 6 , 905 ,774 ( 0 . 1 - 5 wt. % ) . phosphate and phosphoric acid ( such as Pl ) was used , making an A / B / C three - layer structure as shown in Tables 1 , 2 , 3 respectively . Like Example 1 , this Comparative TABLE 1 Example comprised 0 . 5 wt % of silicone masterbatch . The Blend Composition ( in wt % of Layer A results of the food release test are listed in Table 4 Resin Layer Comparative Example 4 Sili Thick [0115 ] Example 2a was repeated with the only difference cone Wax ness , being that the major polyester resin ( base resin ) ws P2 Example P1 P2 P3 P4 MB MB um ( standar film -grade PET ) and no PET resin comprising alkali C . Ex . 1 97 % 3 % 0 % 1. 5 metal phosphate and phosphoric acid (such as P1) was used , Ex . 1 94 . 5 % 5 % 0 . 5 % 1. 5 making an A / B / C three - layer structure as shown in Tables Ex . la 96 . 5 % III 3 % 0 . 5 % 1 . 5 1 , 2 , 3 respectively . Like Example 2 , this Comparative Ex . 2 94 % 5 % 1 % 1 . 5 1 . 5 Ex . 2a 96 % | 3 % 1 % Example comprised 1 .0 wt % of silicone masterbatch in Ex. 3 93 % 5 % 2 % 1 . 5 layer A . The results of the food release test are listed in Table Ex. airaw 4 93. 9 % 5 .6 % 0 . 5 % | 1 . 5 Ex . 5 93 . 9 % 5 . 6 % 0 . 5 % 1. 5 Ex . 6 93. 9 % 5 .6 % 0 . 5 % 1 . 5 Comparative Example 5 C . Ex . 2 95 % 5 % 0 % 1 . 8 C . Ex . 3 94 . 5 % 5 % 0 . 5 % 1 . 5 [ 0116 ] A 2 - layer BOPET film structure was produced by C. Ex. 4 94 % 5 % 1 % 1 . 5 melt extrusion through two extruders supplying the resin C . Ex. 5 95 % 3 % 2 % 1 . 8 C . Ex . 6 - 93 % - 3 % 4 % 1 . 8 blends corresponding to layers A and B and then formed into C . Ex . 7 94 . 5 % 5 % 0 . 5 % 1 . 5 a biaxially oriented film by casting on a cooling drum held C . Ex . 8 94 . 5 % 5 % 0 . 5 % — 1 . 5 at 21° C ., stretching 3 times along the machine direction at Ex . 7 95 % - 0 . 5 % 4 . 5 % 1 . 5 a temperature of 82° C . , and subsequently stretching 4 times along the transverse direction through an oven held at a US 2017 /0326842 A1 Nov . 16 , 2017

TABLE 2 TABLE 2 - continued Blend Composition ( in wt % ) of Layer B Steel Lamination Temperature and Results of Food Release Test Resin Layer Major PET Food Resin in % Silicone Metal Lamination Release Example P1 P2 P3 P4 COP2 P5 Thickness , um Food Resin in Conditions Test C . Ex . 1 100 % 10 . 7 Contact Food Post % Area 100 % Outer release Contact Lam . Bake with Ex. 1 10 . 7 layer Outer release Temp. Temp . unreleased Ex . 1a 100 % | 10 .7 | Example layer OF. OF. food remains Ex . 2 100 % 10 . 7 (layer A ) Ex . 2a 100 % 10 . 7 Ref. Ex . n / a None ; 400 460 10 % Ex . 3 100 % | 10 . 7 Carnauba Ex . 4 79 . 4 % 5 .6 % 15 % 13 . 5 wax instead

Ex. 5 64. 4 % | 5 . 6 % 30 % 13 . 5 Ex. 6 49 . 4 % 5 . 6 % 45 % 13 . 5 C . Ex . 2 95 % 5 % 10 . 4 [0120 ] These results indicate that films comprising poly C . Ex. 3 100 % 10 . 7 C . Ex. 4 100 % 10 . 7 ester P1 ( an alkali metal phosphate /phosphoric acid com C . Ex. 5 92 % 3 % 55 % - 13 . 5 prising polyester ) in the food release layer perform much C . Ex. 6 92 % 3% 5 % - 13 . 5 better versus comparative compositions containing the same C . Ex . 7 100 % 10 . 7 silicone level but standard ( i. e . not comprising alkali metal C . Ex . 8 79 . 4 % 5 . 6 % 15 % 10 . 4 | phosphate / phosphoric acid ) polyester in the food release Ex. 7 - 6060 % - 5 % - 35 % 10 . 7 layer. [0121 ] For a more in -depth analysis , FIG . 2 plots those results versus silicone content in the A layer in the following TABLE 3 way : One data series groups the data ( C . Ex . 1 and Examples Blend Composition ( in wt % ) of Layer C (examples 1 , 1a , 2 , 2a , and 3 ) corresponding to films comprising resin not shown have only A and B lavers ) P1 as the major PET resin in layer A ; another data series groups the data ( C . Ex . 2 , 4 , 5 , 6 ) comprising resin P2 as a Resin Layer major resin in layer A . A single data point plots the data for the film ofComparative Example 7 ( comprising resin P3 and Example P1 P2 P3 P4 COP1 Thickness , um 0 .25 % silicone ). It is evident that : C . Ex . 1 67 % 30 % 1 . 5 Ex . 1 85 % 15 % ? [0122 ] ( 1 ) The trend line for series P1 lies much lower Ex. la 67 % 30 % ? than the trend line for series P2 , suggesting that there Ex . 2 85 % 15 % ? is improvement by going from standard resin to the Ex . 2a 67 % 30 % ? | resin with improved hydrolytic stability of the inven Ex . 3 85 % 15 % ? 22222? tion , accomplished by incorporating alkali metal phos C . Ex . 3 85 % 15 % 1 C . Ex . 4 85 % 15 % 1 . 5 phate /phosphoric acid in the catalyst/ additive package . Ex . 7 IIIIIIIII 85 % — 15 % 1 . 5 [0123 ] (2 ) The single data point corresponding to Example 7 , i. e . for a different major resin with hydro lytic stability (accomplished by solid - stating to higher TABLE 2 IV ) , i. e . resin P3 , falls generally within the trend line for series P2 , i. e. this resin does not show improvement Steel Lamination Temperature and Results of Food Release Test vs . standard resin . Major PET Food [0124 ] ( 3 ) Additional improvement in food release per Resin in % Silicone Metal Lamination Release formance is noted for both series by incorporating Food Resin in Conditions Test siloxane- based ultra -high molecular weight silicone ; Contact Food Post % Area however a plateau is reached after about 1 wt. % Outer release Contact Lam . Bake with silicone incorporation . layer Outer release Temp . Temp. unreleased Example ( layer A ) layer F . OF. food remains [0125 ] ( 4 ) In the case of series P1 this plateau lies below the benchmark set by the commercial BOPET film of C . Ex . 1 P1 0 .00 % 400 460 14 % Ex . 1 P1 0 .25 % 400 460 11 % the reference example ( film type FN8) once the silicone Ex . la P1 0 . 25 % 400 460 7 % content goes above roughly 0 . 1 wt. % . Ex. 2 P1 0 . 50 % 400 460 9 % Ex. 2a P1 0 . 50 % 400 460 8 % [0126 ] ( 5 ) On the other hand, series P2 plateaus out Ex . 3 1 .00 % 400 460 7 % significantly above the benchmark line set by FN8 , Ex . 4 0 . 50 % 370 440 2 % indicating that it will not be capable to reach the Ex. 5 ??z? 0 . 50 % 370 440 1 % Ex . 6 0 . 50 % 370 440 2 % benchmark value at any silicone addition level. C . Ex . 2 0 . 00 % 400 460 96 % [0127 ] Besides the plateau , another factor that sets the C . Ex . 3 P2 0 . 25 % 400 460 55 % upper silicone level in the food contact layer, from a C . Ex. 4 0 . 50 % 400 460 59 % C . Ex. 5 P2 1 . 00 % 400 460 27 % practical standpoint, is that silicone migration into the food C . Ex . 6 P2 2 . 00 % 400 460 25 % reached levels above those allowed for passing certain Ex . 7 P3 0 . 25 % 400 460 76 % sections of FDA regulation 21 CFR 177 .1630 , as Table 3 indicates : US 2017 /0326842 A1 Nov . 16 , 2017 10

TABLE 3 Results of Migration Test Major PET Resin in Food - wt % Silicone 21 CFR 177 . 1630 21CFR Contact Outer Resin in Food - Methanol Extractables 177 . 1630 release layer Contact Outer (mg / in )after Exposure in : Conditions Example ( layer A ) release layer Ethanol Heptane Water Passed : Ex . 1 P1 0 .25 % n /a < 0 .01 n / a ( f) , ( g ), ( h ) Ex. 2 P1 0 . 50 % n / a < 0 .01 n / a ( f) , ( g ) Ex . 3 1 . 00 % na < 0 .01 n / a ( f ), ( g ) C . Ex. 6 P2 22 .00 % 0 . 05 0 . 15 00 ..05 ( f ), ( g )

[0128 ] The results indicate that silicone levels 2 wt. % and machine : drive side (DS ) , midde distance between drive side above in the food contact layer prevent the film for passing and center (“ DSC ” ) , two points at the center on either side condition ( h ), which is the most critical for use as container of the true center, i. e . center left (“ C - L ” ) and center- right liner for containers subjected to food sterilization processes ( “ C - R ” ) , midde distance between tending side and center that typical exceed 250° F . (“ TSC ” ) , and tending side ( “ TS ” ) . The score , expressed as [ 0129 ] The lower temperatures required for successful percentage of total area occupied by food remains is listed lamination and post - treatment in the case of the examples in Table 4 . comprising PBT in the layer that comes in contact with 0132 ] Additional lamination were conducted at different metal during lamination ( layer B in those cases ) illustrate the laminations and post- bake temperature conditions in order to effectiveness of using PBT as a blend ingredient ( represent investigate the effect on crystallinity remaining on the film ing the category of polyester resin having a melting point of after the steel -lamination process . The reults are plotted in least 20° C . below that of the polyester resin P2 . FIG . 9 . [0130 ] In previous examples the laminated disk sample [0133 ] Example 7 : Comp . Example 8 was repeated with was taken from a random position on the metal - coated web . the exception that 4 .5 wt. % wax masterbatch ( resulting in In the Examples that follow the effect of position was 0 . 9 wt. % wax ) was added in layer A , as shown on Table 1. investigated , both with respect to crystallinity and food The PBT level ( resin " P5 " ) in layer B was increased to 35 release : these Examples help to illustrate the benefit from wt % for reasons unrelated with the scope of this invention incorporating wax in improving mitigation of the effects of and should not affect the release results . Process chamges vs . crystallinity . Example 7 were a lower MD ratio ( 4 . 5 ) and small adjust [0131 ] Comparative Example 8 : ( This is a Comparative ments in MD and TD max . temperatures ( 116° C . and 123° Example {no wax } for the wax addition Example 7 that C . respectively ) ; also TD relaxation temperature was 216° follows ). Two - layer biaxially oriented polyester film , having C . The final film product was subsequently laminated on a layer composition as shown in Tables 1 and 2 was produced sheet of tin - free metal sheet on the B - layer side at the on a film production line consisting of a main extruder and following conditions : lamination temperature 370 - 380 ( 188 a subextruder , casting drum , machine -direction stretching 193° C . ) post bake 430 - 440° F . ( 2221- 227° C . ) . Food release and transverse direction stretching ( stenter oven ). Stretch was tested according to the procedure described earlier at ratios were 4 . 8 in the MD direction and 3 . 7 in the TD five different locations across the laminate width , depending direction . Maximum stretch temperaures were 121° C . in the on the position in the lamination machine : drive side (DS ) , midde distance between drive side and center (“ DSC ” ) , MD and 104° C . in the TD . Following TD orientation , there center , midde distance between tending side and center was a 5 % relaxation section at 233° C . Final line speed was (" TSC ” ) , and tending side ( “ TS ” ) . The score , expressed as 288 m / min . The final film product was subsequently lami percentage of total area occupied by food remains is listed nated on a sheet of tin - free metal sheet on the B - layer side in Table 4 . underthe following conditions: lamination temperature 370 10134 ] Additional laminations were conducted at different 380° F . ( 188 - 193° C . ) ; post bake 430 -440° F . ( 2221 - 227° lamination and post - bake temperature conditions in order to C . ) . Food release was tested according to the procedure investigate the effect on crystallinity remaining on the film described earlier at six different locations across the lami after the steel- lamination process. The reults are plotted in nate width , depending on the position in the lamination FIG . 10 . TABLE 4 Results of food release testing at different locations across the lamination width for Example 7 and Comp . Example 8 . Skin Layer Ingredients (Wt % ) Silicone Wax Food Release Test ( % coverage ) Example P1 MB M B DS DSC Center TSC TS DS Avg. C . 8 94 . 5 % 0 . 5 % - 26 % 3 % Left Right 34 % 9 % 33 % 40 % 86 % 94 . 5 % 0 . 5 % 4 . 5 % 6 % 3 % 7 % 29 % 4 % 10 % US 2017 /0326842 A1 Nov . 16 , 2017

[0135 ] The results of the food release tests on Example 7 13 . The polyester film of claim 6 , where the polyester and Comparative Example 8 , along with the crystallinity resin having a melting point of least 20° C . below that of the testing support the fact that the addition of wax , whereas not polyester resin P2 comprises butylene terephthalate repeat improving crystallization , it helps nevertheless to mitigate units. the effect of loss of crystallinity on food release properties . 14 . The polyester film of claim 6 , wherein the at least one This is evident, for example , by the food release score layer comprises an outer release layer having a food area around the center (where crystallinity almost vanishes in coverage of about 10 % or less as measured according to both Examples ) which is much better for the wax - containing Food Release Test . sample ( Example 7 ) vs . the control (Comp . Example 8 ) . 15 . The polyester film of claim 7 , wherein the at least one Overall , these Examples demonstrate that wax addition to layer comprises an outer release layer having a food area the original design ( food - contact skin A comprising a poly coverage of about 10 % or less as measured according to ester using an alkali metal phosphate in the catalyst package Food Release Test. and a silicone ), which may fall short under certain laminatin 16 . A laminated metal sheet comprising the polyester film circumstances, adds robustness to the meat release proper of claim 1 . ties. 17. A laminated metal sheet comprising the polyester film 10136 ] All US patents and publications cited in the present of claim 6 . application are incorporated herein in their entirety by 18 . A laminated metal sheet comprising the polyester film reference . of claim 7 . What is claimed is : 19 . The laminated metal sheet of claim 15 , wherein the at 1 . A polyester film comprising at least one layer compris least one layer comprises an outer release layer having a ing : ( a ) 0 . 1 - 99 . 9 wt . % of a polyester resin P1 comprising an food area coverage of about 10 % or less as measured alkali metal phosphate in an amount of 1 . 3 mol/ ton of the ? polyester resin P1 to 3 .0 mol/ ton of the polyester resin P1 , 20 . The laminated metal sheet of claim 16 , wherein the and phosphoric acid in an amount of from 0 . 4 to 1 . 5 times outer release layer has a food area coverage of about 10 % or by mole that of the alkali metal phosphate ; ( b ) 0 . 1 - 2 wt. % less as measured according to Food Release Test. of a silicone resin comprising a polydiemthylsiloxane resin ; 21 . The laminated metal sheet of claim 17 , wherein the wherein the polyester film is free of Bisphenol A ; and ( c ) a outer release layer has a food area coverage of about 10 % or wax component. less as measured according to Food Release Test. 2 . The polyester film of claim 1 , where the wax compo 22 . The polyester film of claim 1 , wherein the silicone nent comprises a carnauba wax . resin has a kinematic viscosity ranging from 10 - 50x100 3 . The polyester film of claim 1 , wherein the polyester centistokes at room temperature . resin P1 comprises an aromatic polyester. 23 . The polyester film of claim 1 , wherein an amount of 4 . The polyester film of claim 3 , wherein the aromatic the wax component is 0 . 01 - 0 .09 wt. % . polyester comprises at least 50 wt. % ethylene terephthalate 24 . A polyester film comprising at least one layer com as a constituent component of the aromatic polyester. prising : ( a ) 0 . 1- 99. 9 wt. % of a polyester resin P1 compris 5 . The polyester film of claim 1 , wherein the at least one ing an alkali metal phosphate and phosphoric acid ; and layer comprises an outer release layer having a food area ( b ) 0 . 1 - 2 wt. % of a silicone resin ; wherein the polyester coverage of about 10 % or less as measured according to film is free of Bisphenol A ; Food Release Test. wherein relative crystallinity values (counts per second ) , 6 . The polyester film of claim 1 , wherein the at least one determined by XRD ( X - ray diffraction test ) measured layer comprises an outer release layer, further comprising a at different locations of the polyester film after steel heat- sealable layer B comprising ( a ) 0 . 1 - 100 wt. % of a lamination at a given lamination and post -bake tem polyester resin P2 , wherein the polyester resin P2 is crys perature settings is lower than that of a film having the tallizable and different from the polyester resin P1 ; ( b ) same structure and composition as that of the polyester 0 . 1 - 100 wt. % an amorphous copolyester resin or a polyester film except that the film contains no wax component. resin having a melting point of least 20° C . below that of the 25 . The polyester film of claim 24 , wherein the alkali polyester resin P2 ; and (c ) 0 . 1 - 15 wt. % of an antiblock metal phosphate is in an amount of 1 . 3 mol/ ton of the comprising organic or inorganic particles. polyester resin P1 to 3 . 0 mol/ ton of the polyester resin P1 . 7 . The polyester film of claim 6 , further comprising a 26 . The polyester film of claim 24 , wherein the phos heat - sealable layer Chaving a same or substantially a same phoric acid is in an amount of from 0 . 4 to 1 . 5 times by mole composition as that of the heat -sealable layer B . that of the alkali metal phosphate . 8 . The polyester film of claim 6 , further comprising a 27 . The polyester film of claim 24 , wherein the silicone heat - sealable layer C having a different composition from resin comprises a polydiemthylsiloxane resin . that of the heat -sealable layer B . 28 . The polyester film of claim 24 , wherein the at least one 9 . The polyester film of claim 6 , wherein the polyester P2 layer further comprises a wax component. comprises an aromatic polyester . 29 . The polyester film of claim 28 , wherein the wax 10 . The polyester film of claim 7 , wherein the polyester component comprises wax . resin P2 comprises an aromatic polyester. 30 . The polyester film of claim 29 , wherein the wax 11. The polyester film of claim 6 , wherein the polyester component comprises a carnauba wax . resin P2 comprises at least 50 wt. % ethylene terephthalate 31 . The polyester film of claim 24 , wherein an amount of as a constituent component of the polyester resin P2 . the wax component is 0 . 01 - 0 .09 wt. % . 12 . The polyester film of claim 7 , wherein the polyester 32 . The polyester film of claim 24 ,wherein the at least one resin P2 comprises at least 50 wt. % ethylene terephthalate layer comprises a material that causes the relative crystal as a constituent component of the polyester resin P2 . linity values ( counts per second ) , determined by XRD US 2017 /0326842 A1 Nov . 16 , 2017 12

( X - ray diffraction test ) measured at different locations of the polyester film after steel lamination at the given lamination and post - bake temperature settings to be lower than that of the film containing no wax component. * * * * *