JP2021521319A - Polyester film incorporating silicone for release of canned MEAT products - Google Patents

Abstract

The embodiments herein relate to bisphenol A-free multilayer biaxially oriented polyester (BOPET) films for lamination on metal sheets that can be used in food containers. BOPET film has at least one outer layer release layer, and when food is cooked and sterilized in direct contact with the outer layer release layer, it helps release foods such as high protein food sources. The BOPET film can be laminated to the metal used in the manufacture of food containers with an exposed outer layer release layer to allow direct food contact between the surface of the outer layer release layer and the food. .. More specifically, the present invention relates to ultrahigh molecular weight siloxane polymers and polyethylene trephthalate resins; as well as catalyst / additive packages to the components forming the outer release layer resin composition during polymerization of the outer release layer resin composition. The present invention relates to a novel outer release layer resin composition containing an alkali-metal phosphate and a phosphoric acid compound to be added. A wax component is added to the outer release layer to obtain stronger release performance. [Selection diagram] None

Description

[Related application]
This patent application claims priority to US application number 15 / 0663,142 filed on July 28, 2017, which is incorporated herein by reference in its entirety.

The present invention relates to bisphenol A ("BPA") -free multilayer films such as biaxially oriented polyester (BOPET) films for lamination on metal sheets that can be used in food containers. More specifically, the multilayer film has an outer release layer that aids in the release of foods such as high protein food sources when cooking and sterilizing the food in direct contact with the outer release layer.

[Principle of canning food]
Unlike pasteurized "heated" meat products, where the survival of thermostable microorganisms is recognized, the purpose of sterilization of meat products is to destroy all contaminating bacteria, including their spores. Heat treatment of such products may be strong enough to inactivate / kill the most thermostable bacterial microorganisms that are Bacillus and Clostridium spores. In practice, meat products filled in sealed containers are exposed to temperatures above 100 ° C in a pressure cooker. Depending on the product type, it can reach temperatures above 100 ° C, usually 110-130 ° C. The product is stored for a period of time at the temperature level required for sterilization, depending on the type of product and the size of the container.

If the canned product does not completely inactivate the spores, vegetative microorganisms will grow from the spores as soon as the conditions become favorable again. In the case of heated processed meat, suitable conditions will exist once the heat is complete and the product is stored at ambient temperature.

Surviving microorganisms can either spoil stored meat products or produce toxins that cause food poisoning in consumers, and among the two groups of spore-producing microorganisms, Clostridium is better than Bacillus. Is also heat resistant. At a temperature of 110 ° C, most Bacillus spores die in a short period of time. In the case of Clostridium, temperatures up to 121 ° C are required to kill spores in a relatively short time.

The above sterilization temperature is required for short-term (within seconds) inactivation of Bacillus or Clostridium spores. These spores can be sterilized at a slightly lower temperature, but in such cases, the heat treatment period may be lengthened to reach the same level of heat treatment.

From a microbiological point of view, it would be ideal to employ a very intensive heat treatment that eliminates the risk of living microorganisms. However, most canned meat products do not suffer from sensory quality degradation such as very soft texture, jelly and fat separation, discoloration, unwanted heat treatment taste and loss of nutritional value (destruction of vitamin and protein components). , Cannot be subjected to such intensive heat stress.

In order to meet the above perspectives, no compromise must be reached to be sufficient for the microbiological safety of the product and to maintain the moderate heat sterilization possible for product quality reasons. It doesn't become.

[Meat products suitable for canning]
Virtually all processed meat products that require heat treatment during cooking for consumption are suitable for heat storage. Meat products that do not undergo any heat treatment prior to ingestion, such as dried meat, prosciutto or dry sausage, are naturally unsuitable for canning as they are stored with low pH and / or low water activity.

The group of meat products is often produced as canned products, but not limited to: cooked ham or pork shoulders; frank fullter type sausages with brine; bologna or lever sausage type sausage mix; square meat Meat preparations such as shredded pork; meat cooked dishes such as beef with meat, chicken with rice, chicken soup or soup with meat ingredients such as octail soup.

[Can lid]
Metallic food and beverage containers, such as cans, have an inner surface covered with a coating. This coating is essential to prevent container corrosion and food and beverage contamination with dissolved metals. It also helps prevent canned foods from becoming dirty and spoiled by bacterial contamination. The main type of internal coating for food containers is made from epoxy resin and is widely accepted as a protective coating due to its exceptional combination therapy of toughness, adhesiveness, moldability and chemical resistance. Such coatings are essentially inert and have been used for over 40 years. These coatings not only prevent spoilage of the contents, but also allow the food to extend its shelf life while maintaining its quality and taste.

However, these epoxy polymers may contain residual amounts of chemical building blocks called BPA and face a lot of scrutiny from consumer advocacy groups. In Proposition 65, California proposes a second time to list BPA as a cause of reproductive toxicity. As described above, there is a desire to eliminate BPA-based epoxy resin as a protective coating.

For the past decade, consumers and health professionals have raised concerns about the use of BPA in food packaging. Because this molecule is similar in shape to estrogen, it can act as an endocrine disruptor.

Therefore, food companies are anxious to move away from BPA-based food packaging. Coating manufacturers and their suppliers are working overtime to find a universal epoxy alternative made by reacting BPA with epichlorohydrin. In short, there is an urgent need for BPA-free coating of food containers. The BPA-free BOPET film of the present invention demonstrates this need.

Laminating the polyester film on the metal before forming the container portion is one solution for replacing the container lined with an epoxy coating. Biaxially oriented polyethylene terephthalate (BOPET) films are used in multiple applications such as food packaging, cosmetics, and labels.

The food packaging industry uses BOPET film in many heat-sealed tray applications where food can come into direct contact with BOPET, but food release from the surface of the BOPET film is inadequate.

[Food Release]
One of the problems caused by cooking and sterilizing foods in containers, especially for foods containing significant amounts of solids, such as meat products, is the adhesion of solid food particles to the inner container surface. Emission of the entire contents can be a problem. To deal with this phenomenon, wax (
Various methods incorporating US Pat. No. 6,652,979, US Pat. No. 6,905,774, US Pat. No. 7,198,856, US Pat. No. 7,435,465) or silicon compounds (US Pat. No. 6,905,774) have been proposed in the patent literature.

U.S. Pat. No. 6,652,979 U.S. Pat. No. 6,905,774 U.S. Pat. No. 7,198,856 U.S. Pat. No. 7,435,465

Embodiments herein include: (a) 0.1-99.9 wt% of polyester resin P1 containing an amount of 1.3 mol / ton of polyester resin P1 and 0.4-1.5 of alkali metal phosphate. Molar amount of phosphoric acid at the time; (b) 0.1 to 2 wt% of silicone resin containing polydiemtyl siloxane resin; (c) containing polyester resin P1 optionally containing 0.001 to 0.09 wt% wax component; and polyester film Concers with polyester films containing polyester films that do not contain bisphenol A. In one embodiment, the polyester resin P1 comprises an aromatic polyester. In one embodiment, the aromatic polyester comprises at least 50% by weight ethylene terephthalate as a constituent of the aromatic polyester. In one embodiment, at least one layer comprises an outer release layer having a food area coverage of about 10% or less, as measured according to the food release test.

In one embodiment, the film structure comprising at least the outer release layer A comprises (a) 0.1-100% by weight of the polyester resin P2, where the polyester resin P2 is crystallizable and is what the polyester resin P1 is. Different, (b) 0.1-100% by weight of polyester resin having a melting point at least 20 ° C lower than the melting point of amorphous copolyester resin or polyester resin P2, and (c) 0.1-0.1 of anti-lock containing organic or inorganic particles. It further comprises a heat-sealing layer B containing 15% by weight. In one embodiment, the polyester film further comprises a heat sealable layer C having the same or substantially the same composition as the heat sealable layer B, and in one embodiment the polyester film is a heat sealable layer. Further comprising a heat sealable layer C having a composition different from B, in one embodiment the polyester P2 comprises an aromatic polyester. In one embodiment, the polyester resin P2 comprises at least 50% by weight ethylene terephthalate as a constituent of the polyester resin P2. In one embodiment, the component (b) of the polyester resin that is at least 20 ° C. lower than the melting point of the polyester resin P2 is essentially polybutylene terephthalate (PBT) resin.

Another embodiment relates to a laminated metal sheet comprising the polyester film of the embodiments of the present specification. In one embodiment, the silicone resin has kinematic viscosities in the range of 10-50 x 10 cm stalk at room temperature.

This patent or application document contains at least one drawing made in color.
A copy of this patent or publication of the patent application, accompanied by colored drawings, will be provided by the Patent and Trademark Office upon request and payment of the required fees.

Figure 1 shows photographs of the various ingredients used in the preparation of food mixtures for food release testing.

FIG. 2 shows photographs of BOPET laminated metal discs and non-laminated BOPET film.

Figure 3 shows a photograph of the food mixture inserted in a bottle sealed with a cap on a BOPET laminated metal disc, with the BOPET film in contact with the food mixture.

FIG. 4 is a photograph of a pressure cooker with a plurality of closed jars and a heating stove containing a food mixture in a pressure cooker.

FIG. 5 is a photograph showing the removal of BOPET laminated metal discs from a heated food mixture.

FIG. 6 shows a photograph of a BOPET laminated metal disc showing good and bad releases of the cooked food mixture from the BOPET film surface of the BOPET laminated metal disc.

FIG. 7 shows a photograph of a BOPET laminated metal disc (“test sample”) after a food release test in which a grid is layered on a BOPET laminated metal disc, showing the food area coverage with the cooked food mixture still attached to the BOPET film. Is calculated.

FIG. 8 shows a plot of the food area ratio where the cooked food mixture remains attached to the BOPET film as a function of the weight percent of the ultra-high molecular weight silicone.

Figure 9 shows a plot of relative crystallinity values (counts per second) measured by XRD (X-ray diffraction test) measured at different positions on the film of Comparative Example 8 with indicated lamination and post-baking temperature settings. Shown after steel lamination at.

FIG. 10 shows the relative crystallinity values (seconds) determined by XRD (X-ray diffraction test) measured at different positions on the film of Example 7 after steel lamination at the indicated pre-heating and post-heating temperature settings. It is a plot showing the count per).

Embodiments herein relate to polyester films, i.e. BOPET films, which are resistant to retort sterilization temperatures and temperatures associated with barrier properties to provide corrosion resistance to metal containers by food. Has excellent heat resistance. The BOPET film can be laminated and formed on a metal plate for the container forming process. In addition, BOPET film can provide a sufficient release surface that allows high protein foods (meat products) to be easily removed from the container after high heat sterilization. Surprisingly, we found that the release effect imparted by incorporating a silicone containing an ultra-high molecular weight siloxane was achieved by using a polyester resin carrier containing an alkali metal phosphate and phosphoric acid during polymerization. It was found to be significantly enhanced. The original purpose of the alkali metal phosphate / phosphate package was to improve hydrolysis resistance, and the additional benefit of enhanced silicon release was a surprising finding.

The BOPET film can include one or more layers, preferably at least two layers. The multilayer BOPET film can contain one or more of each of the following: container side or inner layer (ie, heat seal or metal bonding layer), food or outer layer, food release layer. In addition, there may be one or more core layers in direct contact with the food stored in the container between the layer bonded to the metal surface and the food side layer.

[BOPET film]
A film that can be laminated on a metal plate for canning, which is generally made of tin-free steel (TFS), electrotin-plated steel (ETP), or aluminum, and the film is 2.0% or less after heat treatment at 210 ° C. It is characterized by dimensional change. As part of the continuous lamination process.

The films disclosed herein include two or three layers of simultaneously extruded and biaxially extruded structures. The outer release layer and any lower "skin" layer are generally thinner than the core "main" layer. The outer release layer (henceforth referred to as "Skin A") typically contains an ultra-high molecular weight silicone (siloxane-based) resin, which is premixed with a copolyester elastomer resin to "master". It forms a "batch" and is then added at low levels into the outer release layer during simultaneous release.

The term "ultra high molecular weight silicone" or "UHMW PDMS" (where PDMS means polydiemtylsiloxane) refers to PDMS resin, which UHMW PDMS has a kinematic viscosity in the range of 10-50 x 106 centimeters at room temperature. Have. (G.
A paper published in "Shearer", Chapter 2, "Silicone in Industrial Applications", Inorganic Polymers, Roger de Jaeger, Nova Science Publishers, 2007) 15). According to the references mentioned above, the advantage of UHMW PDMS is that it forms a stable droplet domain as pellets in various thermoplastic carriers so that it can be easily added directly to the thermoplastic during processing. Another advantage of UHMW PDMS is that it does not bleed from BOPET and at the same time moves to the surface of the BOPET film, thereby providing the desired release properties.

A typical UHMW silicon concentration in a masterbatch is 50 wt. %. The masterbatch addition level in the outer release layer was in the range of 0.2-4% by weight, and the siloxane content of the net was in the range of 0.1-2%. The remaining components of the outer layer are a polyethylene terephthalate (PET) resin composition containing an alkali metal phosphate as a phosphorus compound of 1.3 mol / ton to 3.0 mol / ton, and 0.4 to 1.5 times (by mol) of the alkali metal phosphate. ) Is a polyethylene terephthalate (PET) resin composition containing a phosphate as a phosphorus compound. (Main component), and in some cases inorganic particles for anti-blocking purposes. A typical inorganic particle composition in this case is silica (silicon dioxide, SiO2) with a size in the range of submicrons to a few microns. Silica particles are typically added during coextrusion in the form of concentrated PET chips (“silica master chips”) made by adding silica during polymerization. The typical silica content in the silica master chip is 1-3% by weight; the typical addition level of the silica master chip in the outer release layer is 1-15% by weight, resulting in the silica content of the net. Is around 0.1 to 3% by weight.

Release layer A can also contain a wax component for stronger release performance. The term "wax component" refers to a component containing wax or a wax-like substance. Waxes are various classes of organic compounds that are hydrophobic, flexible solids near environmental temperatures. They contain higher alkanes and lipids, typically having a melting point above about 40 ° C (104 ° C) and melting into a low viscosity liquid. Wax is insoluble in water but soluble in organic and non-polar solvents. Various types of natural waxes are produced by plants and animals and are present in petroleum (source: https://en.wikipedia.org/wiki/Wax). "Wax-like substance" refers to a substance that has the properties of a wax but is not a wax.

The amount of wax component added is 0.001 to 0.090% by weight. Examples of such waxes are described in US Patent No. 6,905,774, which is incorporated herein by reference in its entirety. Specifically, examples of wax compounds that can be used here are esters of aliphatic carboxylic acid compounds and aliphatic alcohol compounds, and amides of aliphatic carboxylic acid compounds and aliphatic amine compounds, preferably. The wax is composed of compounds having a total number of carbons of 30-120, more preferably 40-100. Synthesis including aliphatic esters such as stearyl stearic acid, carnauba wax, candelilla wax, rice wax, pentaerythrititol fur ester, behenyl behenate, palmityl myristate and stearyl triglyceride as examples of such compounds. Alternatively, natural wax is preferable from the viewpoint of compatibility with polyester.

In particular, the addition of carnauba wax is preferable, and particularly purified, from the viewpoints of remarkable release characteristics after repeated use, use after production and use in an aquatic environment, development of non-adsorption in food packaging applications, and improvement of hygiene. Carnauba wax is preferred.

The term "robust performance" specifically relates to commercially available metal lamination equipment and, due to process limitations, across the web width, in terms of thermal history, and correspondingly, in terms of the final form of the laminated film. Therefore, it is variable. Such an installation is described in US Pat. No. 9,358,766. Commercially available metal lamination rows have two important factors that influence such morphology: one is the preheat temperature of the steel sheet just before contacting the polyester film at the point of lamination (a pair of nip rolls). Or one or both are heated). For biaxially oriented PET base films, this temperature is between 320 and 430 ° F, preferably between 360 and 430 ° F. The second is the temperature setting in a post-heating station (eg, an infrared (IR) heating oven), which stabilizes the initial bond between the plastic film and the steel formed during the laminating process. Useful. For biaxially oriented PET base films, this temperature is between 350 and 500 ° F, preferably between 420 and 460 ° F. As the laminated sheet exits the post-treatment (“post-baking” station), the morphological variation of the laminated polyester film is, for example, crystallinity at each spot across the laminate width (eg, determined by X-ray dichotomy-XRD). Revealed by; crystallinity is also affected by both preheat and postheat temperatures. The profile of the relative crystallinity value (counts per second) measured by XRD for the wax-free film is shown in FIG. 9, and the wax-containing film is shown in FIG. When wax is added, the relative crystallinity value (counts per second) measured by XRD (X-ray diffraction test) measured at different positions on the film after steel lamination at the given lamination and temperature settings after baking. However, it was surprisingly found to be lower than that of the wax-free film of FIG. 9, as shown in FIG. It was also surprisingly found that the Figure 10 film released better food than the Figure 9 film. When combined with siloxane and PET resin P1 (PET resin consisting of alkali metal phosphate and phosphate), the amount of wax required to release the meat is a film that uses only wax due to its release properties (Toray Industries). Less than the wax present in Lumirror TM grade FN8 polyester film, etc.). The film is impregnated with carnauba wax formulated at the levels prescribed by 35 USC 6,652,979 (0.1-2% by weight) or 35,954,774 (0.1-5% by weight).

The remaining two layers are hereinafter referred to as layer "B" for the core layer and "A" for the skin layer lying on the opposite side and "C" for the skin layer. The thickness distribution ranges from 5 to 30%, 40 to 95%, and 0 to 30% for layers A, B, and C, respectively, based on the overall film thickness. A typical total film thickness after biaxial stretching is 10 to 25 microns, preferably 12 to 23 microns.

The two- or three-layer film structure is laminated on a metal sheet (steel or aluminum) and then formed in a container. Although both sides of the metal sheet can be laminated with a plastic film, the film of the present invention is intended to be the inner surface of the container and the outer release layer containing silicone is from the food contact layer (ie from the metal substrate of the can). It is intended to be laminated on the metal sheet side so that it is a separate layer).

Core layer B can contain 100% by weight PET resin (“base resin”). In the absence of layer C, layer B can also include an anti-block containing masterbatch or low melting point copolyester, as described in more detail for any layer C.

Any skin layer C can be a blend of PET-based resins with low temperature melting (against crystalline PET) or amorphous polyester copolymers, or lower melting (or amorphous) polyester copolymers. Examples of low melting point polyesters are butylene terephthalate repeating units such as poly (butylene terephthalate) ("PBT") resin, and other dicarboxylic acids or diols such as isophthalic acid, naphthalenedicarboxylic acid, azelaic acid, sebacic acid, adipic acid. , Ethylene glycol, 1,3-propanediol, 1-2propanediol, neopentyl glycol, 1,4-cyclohexyldimethanol, etc. and their copolymers. A non-exhaustive list of suitable examples of polybutylene terephthalate (PBT) resins is as follows: Crastin (R) FG6129, DuPont's Crastin (R) FG6130, Celanese 1600, Ticona's Celanese (R) 1700, TorayconTM1100M, TorayconTM1200M from Toray Industries, etc. Another example of lower fused polyesters is trimethylene terephthalate repeating units such as poly (trimethylene terephthalate) (PTT) resins and their other dicarboxylic acids or diols such as isophthalic acid, naphthalenedicarboxylic acid, azelaic acid, sebacic acid. It is a resin containing a copolymer of acid, adipic acid, ethylene glycol, 1,4-butanediol, 1-2propanediol, neopentyl glycol, 1,4-cyclohexyldimethanol and the like. A non-exhaustive list of suitable examples of polytrimethylene terephthalate (PTT) resins can be Solona (R) (DuPont), Cortera (R) (Shell), Ecoliex (R) (SK Chemistry). The purpose of adding a low melting point or amorphous polyester copolymer to the layer is to facilitate adhesion to the metal during thermal lamination. However, it is not necessary to add such a copolymer in order to make the metal contact layer heat-sealed. This is because the temperature of the lamination and subsequent oven treatment can be adjusted to a value that makes the metal contact side sticky enough to bond with the metal. PET polyesters have a melting point peak near 250 ° C, whereas melting point initiation occurs near 205 ° C (400 F), which is consistent with stacking temperature conditions and facilitates initial bonding at pressure of laminated nip rolls. Is further strengthened by oven treatment of the laminated structure at around 460 ° C.

[Polyester resin composition]
The resin of layer A is "P1", a polyester resin containing a buffer solution soluble in ethylene glycol and containing a substance exhibiting ionic dissociation. Such buffers are preferably alkali metal salts such as phthalic acid, citric acid, carbonic acid, lactic acid, tartaric acid, phosphoric acid, phosphoric acid, hypophosphite salts; alkali metal salts of polyacrylic acid compounds and the like. .. More specifically, since the alkali metal is potassium or sodium, sodium dihydrogen citrate, potassium hydrogen citrate, potassium hydrogen citrate, sodium carbonate, sodium tartrate, potassium tartrate, sodium lactate, sodium carbonate, sodium hydrogen phosphate. , Potassium hydrogen phosphate, potassium hydrogen phosphate, sodium dihydrogen phosphate, sodium dihydrogen phosphate, sodium hypophosphite, sodium hypochlorite, sodium polyacrylate, etc. be able to.

In a preferred embodiment, P1 is an alkali metal phosphate as a primary phosphorus compound in an amount of 1.3 mol / ton to 3.0 mol / ton of polyester resin, and a second in an amount 0.4 to 1.5 times that of the alkali metal phosphate. It is a polyester resin composition containing phosphoric acid as a phosphorus compound. The polyester resin composition preferably contains a dicarboxylic acid component having a molar amount of 95% or more of the acid component. In particular, the terephthalic acid component is preferable from the viewpoint of mechanical properties. From the viewpoint of mechanical properties and thermal properties, the glycol component preferably contains a linear alkylene glycol having 2 to 4 carbon atoms in an amount of 95 mol or more.

In particular, ethylene glycol having two carbon atoms is preferable from the viewpoint of moldability and crystallization of the polyester resin. Of terephthalic acid and additional polyester raw materials of ethylene glycol, for example diacids such as isophthalic acid, naphthalenedicarboxylic acid or 1,4-cyclohexyldimethanol, diethylene glycol, 1,3-prolylen glycol, 1,4-butylene glycol In addition to such diols, they may be present as copolymerization components in the polyester composition polymerization mixture at levels up to 5 mol% of total diacids or diols. If the content of the copolymerization component exceeds 5% mol, this will cause a decrease in heat resistance due to a decrease in melting point, and a decrease in hydrolysis resistance due to a decrease in polyester crystallinity. From the viewpoint of hydrolysis resistance, it is desirable that the polyester resin composition contains an alkali metal phosphate in a polyester resin of 1.3 mol / ton to 3.0 mol / ton. A polyester resin of 1.5 mol / ton to 2.0 mol / ton is desirable. If the content of alkali metal phosphate is less than 1.3 mol / ton of polyester resin, long-term hydrolysis resistance may be insufficient. On the other hand, when the alkali metal phosphate is contained in the polyester resin in an amount exceeding 3.0 mol / ton, phase separation (precipitation) of the alkali metal phosphate is likely to occur.

Examples of alkali metal phosphates include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, lithium dihydrogen phosphate, Examples thereof include dipotassium hydrogen phosphate and trilithium phosphate.

Preferred examples of alkali metal phosphates are alkali metal dihydrogen phosphates and alkali metal phosphates. Alkali metal phosphates in which the alkali metal is Na or K are preferred from the standpoint of long-term hydrolysis resistance. Particularly preferred examples of alkali metal phosphates are sodium dihydrogen phosphate and potassium dihydrogen phosphate. It is desirable that phosphoric acid has a molar ratio of 0.4 to 1.5 times that of alkali metal phosphate from the viewpoint of long-term hydrolysis resistance. It is preferably 0.8 to 1.4 times. If it is less than 0.4 times, long-term hydrolysis resistance may deteriorate. If it exceeds 1.5 times, excess phosphoric acid inactivates the polymerization catalyst; this results in a delay in polymerization and an increase in the amount of end group COOH, which is the hydrolysis resistance of the polyester resin. Will contribute to the decomposition of.

According to the calculation based on the contents of alkali metal phosphate and phosphoric acid, the polyester resin composition contains an alkali metal element in 1.3 mol / ton to 9.0 mol / ton of the polyester resin and 1.8 mol / ton to 7.5 mol of the polyester resin. Contains phosphorus in / ton. Considering the types of preferred alkali metal phosphates, the polyester resin composition preferably contains an alkali metal element in an amount of 1.3 mol / ton to 6.0 mol / ton of the polyester resin, and 1.8 mol / ton to 7.5 mol / ton of the polyester resin. Contains ton amounts of phosphorus.

From the viewpoint of reducing the amount of terminal group COOH and inhibiting the formation of foreign substances, the total amount of phosphorus compounds contained in the polyester resin composition of this composition is the weight of the polyester resin composition from the viewpoint of the amount of phosphorus elements. It is preferably 30 PPM to 150 PPM. This content is more preferably 60 PPM to 150 PPM.

The composition of the polyester resin P1 consists of a metal-containing compound (“metal compound”) in which the metal element is at least one member selected from the group consisting of Na, Li and K, and the metal element is Mg, Ca, Mn and Co. It is preferable that the metal compound is at least one member selected from the group consisting of Sb, Ti and Ge, and the total amount of these metal elements is polyester. It is adjusted to 30 PPM or more and 500 PPM or less based on the entire resin composition. By adjusting the total amount of metal elements within this range, the amount of terminal group COOH in the polyester resin can be reduced and its heat resistance can be improved. This content starts from 40 PPM
More preferably, it is 300 PPM. The elements Na, Li and Ka are alkali metal elements. The divalent metal elements Mg, Ca, Mn, and Co are transesterification catalysts and impart electrostatic properties such as resistance of polyester resin. Sb, Ti and Ge are metal members having the ability to catalyze the polymerization of polyester resin and act as a polymerization catalyst.

[BOPET film process]
The multilayer PET film is preferably biaxially oriented before being laminated on a metal substrate. Typically, the raw material PET resin is supplied in solid form to a melt processing apparatus, preferably a continuous screw extrusion apparatus. The heating of the melt treatment equipment is controlled to keep the PET resin above its melting point but below the polymer degradation temperature. The PET molten resin is extruded from a properly shaped die to form a thin, flat ribbon of polymer melt. The polymer ribbon is quenched in air and / or on a cooled roll to form a solid self-supporting film. The film is taken up by a set of rollers that rotate at different rotational speeds and stretches the film in a direction of continuous forward motion called the mechanical direction ("MD"). Stretching involves heating the film and can establish crystal orientation in MD. The unidirectionally oriented film is clamped and stretched laterally ("TD") laterally to the MD in a tenter oven at the opposite end. The tenter oven is heated to operating temperature to establish crystal orientation within the TD, thus forming a biaxially oriented PET film. Preferably the biaxially oriented PET film is stretched from about 100% to 400% on MD and 100% to 600% on TD. The biaxially oriented film can preferably have a temperature setting between about 300 and about 490, more preferably a heat setting from about 350 to about 460 ° F.

The present invention will be better understood with reference to the following examples intended to illustrate specific embodiments within the overall scope of the invention, but the scope of the invention is the examples. It is not limited to.

[Resin material]
The resin materials for films mentioned in the examples were as follows.

PET resin P1 (PET resin consisting of alkali metal phosphate and phosphoric acid): Toray F1 CCS64 (IV = 0.65; Tm = 255 ° C) supplied by Film Europe.

PET resin P2 (usually film grade PET resin, not containing alkali metal phosphate): Toray F21MP (IV = 0.65; Tm = 255 ° C) manufactured by Toray Plastics America.

PET Resin P3: INVISTA Bottle Grade PET Resin 8712A, IV = 0.75.

PET resin P4: PET resin anti-block masterbatch type F18M (IV = 0.62; Tm = 255 ° C) containing 2% silica particles with an average size of 2 μm (Fuji Silysia 310P) manufactured by Toray Plastics America.

Amorphous copolymer resin CoP1: Eastar (R) 6763 PETG supplied by Eastman Chemical (based on terephthalic acid); 33:67 molar partial combination of CHDM (1,4-cyclohexanedimethanol) / ethyelneglycol Reacted with); IV = 0.76.

Slowly Crystallized Copolyester Resin CoP2: Toray Plastics America's IPET F55M Resin (IV = 0.69; Tm = 205 ° C) is based on a 19:81 mol (= weight in this case) partial combination of isophthalic acid / terephthalic acid. Reacted with ethylene glycol.

Silicone Resin Masterbatch: Contains 50% Ultra High Polymer Polymerized Siloxane (“Silicone Resin”) and 50% Polyester Elastomer Carrier Resin (Dow Corning MB50-010).

Low melting point polyester resin P5: Polybutylene terephthalate (PBT) resin derived from E.I. DuPont De Nemours Crastin (R) FG6130, melting point 223 ° C.

The carnauba wax component was added in the form of a masterbatch (“wax MB”) containing 2% by weight wax available from Toray Industries under the trade name W030.

[General film production procedure]
The multi-layer co-extruded BOPET film was made using a 1.5 m wide pilot phosphorus continuous orientation process. The simultaneously extruded film is cast onto a chill drum using an electrostatic pinner, mechanically oriented through a series of heated, incrementally spy rolls, and then laterally stretched in a tenter oven.

The multi-layer co-extruded laminate sheet is co-extruded by the main extruder to carry the melt and core blend to the die, and by one or two sub-extruders to thaw and carry the skin blend to the die. Extrusion through the main extruder is performed at a processing temperature of approximately 270 ° to 285 ° C. Extrusions are carried out through a sub-extruder at a processing temperature of approximately 270 ° C to 280 ° C. The main and subpolymer melt streams flow through the die to form a laminate co-extrusion structure, cast onto a cooling drum with controlled surface temperature at about 21 ° C, and solidify the non-oriented laminate sheet at a casting rate of about 9 mpm. .. The non-oriented laminated sheet is stretched in the longitudinal direction at about 75 ° C to 85 ° C at an elongation ratio of about 3 times the original length, and the obtained stretched sheet is annealed at about 70 ° C to form a uniaxially oriented laminated sheet. To get.

The uniaxially oriented laminate sheet is introduced into the tenter at a linear velocity of about 27 mpm, preheated at 80 ° C, laterally stretched at about 90 ° C at a stretch ratio of about 4 times the original width, and then about. Heat set or anneal at 210 ° C to reduce internal stress due to orientation, minimize shrinkage, and provide a relatively thermally stable biaxially oriented sheet.

[Procedure for heat lamination of film on metal sheet]
0.0075 "thick tin-free steel (TFS) was preheated to 400 F (unless otherwise indicated). The steel and film passed through a set of nipped rolls that formed the initial bond between the film and steel. The film and steel laminate structure was then passed through a secondary heating operation ("post-baking") at 460 F for 20 seconds and then cooled to room temperature.

The film side laminated on the steel was opposite to the silicon-containing side (food contact side; A side in the example), that is, the laminated side was the B side or the C side in the example.

[Test method]
Various properties in the above examples were measured by the following methods.

Intrinsic viscosity (IV) of film and resin was tested according to ASTM D 4603. This test method uses a glass capillary viscometer to measure poly (ethylene terephthalate) that dissolves in poly (ethylene terephthalate) (PET) at a concentration of 0.50% in a 60/40 ratio of phenol / 1,1,2,2-tetrachloroethane solution. It is a method of intravenous quantification using.

The melting point of the copolyester resin is measured using the TA Instruments Differential Scanning Calorimeter Model 2920. Test 0.007 g of resin sample substantially according to ASTM D3418-03. No preliminary thermal cycle is used and is consistent with ASTM standard Note 6. The sample is then heated to 300 ° C. at a rate of 10 ° C./min and the heat flow and temperature data are recorded. The melting point was reported as the temperature at the endothermic peak.

Film crystallinity was measured by X-ray diffraction on a PANalytical X'Pert PRO system equipped with a Cu X-ray source (40 kV, 20 mA) and an Xe gas proportional detector. The incident X-ray beam is directed at the sample over the angles of the spectrum, and the intensity of the diffracted beam is measured at each angle as a count of the number of pulses per second. A measure of crystallinity designated as "Counts per Second" (cps) is reported based on the count of pulses at the peak intensity of the diffracted beam. [100] Samples were scanned from 18 ° to 32 ° to cover the maximum diffraction angles of both PBT and PET, 2θ = 23.38 ° and 2θ = 25.8 °, for crystallographic planes (angles of peak intensity). .. The preferable cp value before lamination is 1500 or more, and after lamination 900 or more.

[Food release test]
The food area coverage on the food contact side of the polyester film laminated on steel is measured according to the food release test, hereinafter referred to as the "food release test". The procedure for the food release test is described below.

A food mixture with a ratio of 3/2/1 of chicken egg / ground beef / flour was prepared as follows.
A. Food release mixture preparation process shown in Figure 1. In the 8-10 bottle test, 1 lb of ground beef was placed in a mixing container such as a plastic bottle.
・ The contents of 5 large Grade A eggs were added to the mixing container and mixed manually with a paddle or metal rod. ・ 8 oz of general-purpose white powder was slowly added while mixing until the mixture was thoroughly mixed.
B. Place the sample in a glass test bottle as shown in Figures 2 and 3. • Using the shear material from the film / metal laminate described above, cut out a disc small enough to fit the bottom of the bottle (Figure 2): In the examples, a disc with a diameter of 47 mm was used to fit the inside of a half-focus wide-mouthed ball (R) jar. The BOPET film fits the jar and the food mixture as described in the following procedure. Cut to a sheet size large enough to hold. • A sheet of film was placed on top of the jar (separation side), with the food contact side facing up, and then a metal disc was placed on top of it.
A pair of soup spoon-sized scoops of the food release mix was placed on the sample disc. The film was wrapped around the food release mix and the disc sitting under the food release mix.
-The packaged food mixture (including the sample disc at the bottom) was inserted into the jar and the jar was closed.
C. Retest / Test (Figs. 4 and 5)
-The "retort" (pressure cooker as shown in Figure 4) was filled with water up to 0.5 "under the underside of the perforated steam plate.-Place the test bottle on the plate and retort (pressurize). Cooker) The cover was securely put on.
・ The retort was placed on a hot plate set at a medium and high level, and retort was performed for 90 minutes after the pressure valve began to vibrate (internal pressure 14.7 psig, body temperature around 260 ° F).
-It meant that it was safe to open the pressure cooker by removing it from the heat and cooling it until the valve went down.
-Open the pressure cooker, remove the jar with tongs and let it rest overnight-Unravel the film from the food mix (the food mix was still attached to the metal disc).
-The disc was peeled off from the food mixture by orthogonal motion, and the release performance was evaluated. See Figure 6 for good and bad examples of food release.

In the "retort step", the inside or outside of a metal container having a wall made of a composite of a metal base material having a polymer film laminated on the inside, outside or both sides of the base material is treated with live steam or superheated water for a certain period of time. The process of doing.

"Live steam" means that the steam comes into direct contact with the surface of the container. Steam is usually overheated, that is, above the boiling point of water. The nominal retort method requires exposure to steam at a temperature of 260 oF for 90 minutes. The exposure temperature and duration of the retort process can be varied to provide approximately comparable sterilization and pasteurization effects of food. For example, temperatures can be higher for shorter periods and lower for longer periods.

Release performance was evaluated by creating a photographic image of a test laminated disc after release and overlaying a rectangular grid image using Microsoft PaintTM software. After that, the number of grid squares with food left attached was counted and expressed as a percentage of the total number of grid squares. The lower the percentage, the better the food release capacity (Figure 7). The pass rates based on percentages are as follows (based on US Pat. No. 6,905,774):
Grade A ("excellent"): 0-5%
Grade B ("good"): 5-10%
Grade C (“tolerance”): 10-20%
Grade D ("bad"): 20-50%
Grade E ("extremely bad"): 50-100%

[Food migration test]
The study shall be conducted under the conditions specified in the Code of Federal Regulations, Title 21CFR177.1630, conditions (f), (g), (h). Conducted by Madison, WI). The present invention is an invention in which the concentration of a chloroform-soluble extract present in the exposure medium is measured after exposing the food contact surface (in this case, layer A) according to the following specifications for each use condition.

Condition (f): 250 ° F-Allowable for foods excluding alcoholic beige at temperatures not excluding extract Limits: Distill nheptane at 150 ° F for 2 hours 0.5 mg / in 2, distilled water at 250 ° F do.

Conditions (g): Tolerated for alcoholic beverages not exceeding 50% alcohol-Extract limit: 0.5 mg / in after exposure to 50% ethanol at 120 ° F for 24 hours.

Condition (h): 250 ° F-Extract limit: After exposing nheptane at 150 ° F for 2 hours, it is allowed to contain food being calcined or oven-cooked at 2 0.02 mg / in 2.

[Examples 1 and 1a]
The three-layer BOPET film structure was produced by extrusion of melt from three extruders supplying the resin blends corresponding to layers A, B, and C, respectively, as shown in Tables 1, 2, and 3, respectively. The silicone masterbatch content in layer A was 0.5%, corresponding to 0.25% by weight of silicone content. The difference between compositions 1 and 1a was with respect to the antilock masterbatch (P4) content in layer A and the amorphous copolyester (CoP1) content in layer C (and the resulting majority resin balance P1 in layers A and C). And the difference in P2 content is subdivided). The cast film is stretched three times in the mechanical direction at a temperature of 82 ° C, and then stretched four times laterally through an oven held at a stretch zone temperature of 85 to 93 ° C and an annealing zone of 204 ° C to form a biaxially oriented film. It was formed in a roll shape with a rotary winder at a linear speed of 32 m / min.

The film was then laminated with the film A side onto a tin-free metal sheet with side surface C attached to the surface of the metal sheet and tested for food release according to the procedure described above.
Table 4 shows the score expressed as the ratio of the total area occupied by food residue.

[Examples 2 and 2a]
In Examples 1 and 1a, the silicone masterbatch content in layer A is 1.0%, which corresponds to 0.5% by weight of the silicone content, using the A / B / C three-layer structure as shown in Tables 1, 2 and 3. Only repeated with the main difference. Table 4 shows the results of the food release test.

[Example 3]
In Example 1, the only major difference is that the silicone masterbatch content in layer A is 2.0%, which corresponds to 1.0% by weight of silicone content, as shown in Tables 1, 2 and 3, respectively. A / B / C three-layer structure was created. Table 4 shows the results of the food release test.

[Example 4]
A two-layer BOPET film structure was generated by melt extrusion from two extruders supplying the resin blends corresponding to layers A and B, respectively, as shown in Tables 1 and 2, respectively. Layer B contains 15% PBT. The extrusion conditions were the same as those listed in Comparative Example 5. The silicone masterbatch content in layer A was 0.5%, corresponding to 0.25% by weight of silicone content.

[Example 5]
In Example 4, the only difference was that the weight ratio of PBT in layer B increased to 30%.

[Example 6]
In Example 5, the only difference was that the weight ratio of PBT in layer B increased to 45%.

[Comparative example 1]
In Example 1a, the only major difference was that no silicone masterbatch was added to layer A, resulting in a three-layer structure of A / B / C as shown in Tables 1, 2 and 3, respectively. .. The results of the food release test are shown in Table 4.

[Comparative example 2]
In this comparative example, a commercially available biaxial film of bilayers (layers A and B, which are identical except for the fact that layer B contains internal recycling) available from Toray Plastics America grade "Lumirror TM 48G PA66" was used. The film product is based on P2 as the base resin and P4 as the antilock master batch. The A / B structure is shown in Tables 1 and 2, and the results of the food release test are shown in Table 4.

[Comparative example 3]
In Example 1a, the main polyester resin (base resin) is P2 (standard film grade PET), and a PET resin containing alkali metal phosphate and phosphoric acid (P1, etc.) is not used, Table 1, It was repeated with the only difference that it had an A / B / C three-layer structure as shown in 2 and 3. As in Example 1, this comparative example comprises 0.5% by weight of the silicone masterbatch. The results of the food release test are shown in Table 4.

[Comparative example 4]
In Example 2a, the only difference is that the main polyester resin (base resin) ws P2 (standard film grade PET) and alkali metal phosphate and phosphoric acid (P1, etc.) are repeatedly not used with the film PET resin. , A / B / C three-layer structure as shown in Tables 1, 2 and 3, respectively. As in Example 2, this comparative example comprises 1.0% by weight of the silicone masterbatch in layer A. The results of the food release test are listed in Table 4.

[Comparative example 5]
The two-layer BOPET film structure is melt-extruded through two extruders that supply the resin blends corresponding to layers A and B, cast on a cooling drum held at 21 ° C, and machine-wise at a temperature of 82 ° C. Stretched 3 times, then stretched 4 times laterally through an oven kept at a temperature of 85-93 ° C for the stretch zone and 204 ° C for the annealing band, and collected in rolls with a rotary winder at a linear speed of 32 m / min. bottom. The final A / B biaxially oriented bilayer structure is shown in Tables 1 and 2, respectively. As in Example 3, this comparative example comprises 2.0% by weight of the silicone masterbatch in layer A and corresponds to a silicone content of 1% by weight. The results of the food release test are shown in Table 4.

[Comparative example 6]
In Comparative Example 5, the silicone masterbatch content in layer A was 4.0% by weight and the silicone content was 2.0% by weight, which was repeated as the only difference, and A / as shown in Tables 1 and 2, respectively. B Two-layer structure. The results of the food release test are shown in Table 4.

[Comparative example 7]
The only difference is that Comparative Example 3 is repeated (0.5 wt.% Silicone masterbatch in layer A corresponding to 0.25 wt.% Silicone) and the main resin in layer A is P3. As shown in 1 and Table 2, it has a three-layer structure of A / B / C. The results of the food release test are shown in Table 4.

表２：B層のブレンド組成（重量％）

表３：C層（例示せず、A層とB層のみを示す）のブレンド組成（重量％）

表２：鋼積層温度と食品リリース試験の結果

[Reference example]
Reference examples are represented by commercial films currently considered suitable for internal container liners with food release properties, namely Toray Industries' Lumirror TM grade FN8 polyester film. The film is impregnated with carnauba wax formulated at a level in the range prescribed by 35 USC 6,652,979 (0.1-2% by weight) or 35,954,774 (0.1-5% by weight).
Table 1: Blend composition of layer A (% by weight)

Table 2: Blend composition of layer B (% by weight)

Table 3: Blend composition (% by weight) of layer C (not shown, only layer A and layer B are shown)

Table 2: Steel stacking temperature and food release test results

These results show that the film containing polyester P1 (polyester-containing alkali metal phosphoric acid / phosphoric acid) in the food release layer has the same silicon level in the food release layer but is standard (ie, alkali metal phosphoric acid / phosphorus). It shows that it is far superior to the comparative composition containing polyester (without acid).

For more detailed analysis, Figure 2 plots their results against the silicon content in layer A: One data series on film containing resin P1 as the primary PET resin in layer A. Group the corresponding data (C. Ex. 1 and Examples 1, 1a, 2, 2a, and 3); another data series contains resin P2 as the primary resin in the layer (C. Ex. Grouping 2, 4, 5, 6), a single data point plots the data for the film of Comparative Example 7 (including resin P3 and 0.25% silicon). What is clear is the following.
-The trend line of series P1 is much lower than the trend line of series P2, and the hydrolysis stability of the present invention, which is achieved by incorporating alkali metal phosphate / phosphoric acid in the catalyst / additive package, has been improved. It suggests that there is an improvement due to the shift from standard resin to resin.
• For a single data point corresponding to Example 7, ie, a different major resin with hydrolysis stability (which reaches higher IV by solid phase fixation), ie resin P3, is generally within the trend line of series P2. to go into. That is, this resin shows no improvement over the standard resin.
• Further improvements in food release performance are noted for both series by incorporating siloxane-based ultra-high molecular weight silicones; however, plateaus are reached after uptake of approximately 1% by weight silicone.
-For Series P1, this plateau is below the benchmark (when the silicon content is approximately 0.1% by weight or more) set by the commercially available BOPET film of the reference example (film type FN8).
-On the other hand, Series P2 far exceeded the benchmark line set by FN8 and reached the plateau, indicating that the benchmark value could not be reached regardless of the silicone addition level.

In addition to the plateau, another factor that sets the upper limit of silicon levels in the food contact layer is, from a practical point of view, the identification of silicon migration into food by FDA Rule 21 CFR 177.1630, as shown in Table 3. You have reached a level above the level allowed to pass through the section.
Table 3: Mobile test results

The results show that a silicon level of 2 wt.% Or higher in the food contact layer prevents the film for passage condition (h), which is a container subjected to a typical food sterilization process above 250 ° C. Most important for use as a container liner.

For examples that include PBT in layers that come into contact with metal during lamination (layer B in those cases), the lower temperatures required for successful lamination and post-treatment are blended components of PBT (polyester resin P2). Represents a category of polyester resins that have a melting point at least 20 ° C lower than that of).

In the precedent, laminated disc samples were taken from random locations on the metal-coated web. Examples that follow the effect of position were investigated for both crystallinity and food release: these examples illustrate the benefits of incorporating wax in improving the reduction of the effect of crystallinity. Useful.

Comparative Example 8: (Hereinafter, it is Comparative Example {without wax} of Wax Addition Example 7). A bilayer biaxially oriented polyester film having a layer composition as shown in Tables 1 and 2 is placed on a film production line consisting of a main extruder and a secondary extruder, a casting drum, mechanical stretching and lateral stretching (stentor oven). Manufactured in. The elongation ratio was 4.8 in the MD direction and 3.7 in the TD direction. The maximum elongation temperature was 121 ° C for MD and 104 ° C for TD. Following the TD orientation, there was a 5% relaxation section at 233 ° C. The final line speed was 288 m / min. The final film product was then laminated onto a sheet of tin-free metal sheet on the B-layer side under the following conditions: Lamination temperature 370-380 ° C (188-193 ° C); Postbake 430-440 ° C (2221-227). ℃). Food releases were tested at 6 different locations across the width of the laminate, depending on their location within the laminating machine, according to the procedure described above: drive side (DS), intermediate distance between drive side and center ("DSC"), true. Two centers on either side of the center of the center: left center ("CL") and right center ("CR"), intermediate distance between tendon and center ("TSC"), and tendon side ("" TSC "). Table 4 shows the score expressed as the ratio of the total area occupied by the food residue.

Additional laminations were performed under different laminations and post-baking temperature conditions to investigate the effect on the crystallinity remaining on the film after the steel-lamination process. The results are plotted in Figure 9.

Example 7: Comp. Example 8 was repeated, except that a 4.5 wt% wax masterbatch (resulting in 0.9 wt% wax) was added to layer A, as shown in Table 1. PBT levels in layer B (resin "P5") increased to 35% by weight for reasons unrelated to the scope of the invention, but should not affect release results. In the method change vs. Example 7, the MD ratio was low (4.5), the MD and TD maximum temperatures were adjusted to be small (116 ° C and 123 ° C, respectively), and the TD relaxation temperature was also 216 ° C. The final film product was then laminated onto a sheet of tin-free metal sheet on the B-layer side under the following conditions: Laminating temperature 370-380 (188-193 ° C) Postbake 430-440 ° C (2221-227 ° C). Food releases were tested at five different locations across the width of the laminate, depending on their position within the laminating machine, according to the procedure described above: drive side (DS), intermediate distance between drive side and center ("DSC"), center. , The intermediate distance between the tendon side and the center ("TSC"), and the tendon side ("TS"). Table 4 shows the score expressed as the ratio of the total area occupied by the food residue.

Additional laminations were performed under different lamination and post-bake temperature conditions to investigate the effect on the crystallinity remaining on the film after the steel-lamination process. The results are plotted in Figure 10.
Table 4: Results of food release tests at different locations across the lamination widths of Example 7 and Comp

The results of the food release tests of Example 7 and Comparative Example 8 show that, along with the crystallinity test, the addition of wax does not improve crystallinity, but nevertheless mitigates the effect of loss of crystallinity on food release properties. It supports the fact that it is useful for. This is evident, for example, by the food release score around the center, where crystallinity is largely lost in both examples, which is much more than the wax-containing sample (Example 7) vs. the control (Example 8). Good for. Overall, these examples lack the addition of wax to the original design (food contact skin A and silicone containing polyester with alkali metal phosphate in the catalyst package) under certain laminating environments. It demonstrates the potential and adds robustness to the meat release characteristics.

All US patents and published documents cited herein are incorporated herein by reference.

Claims (32)

(a) 1.3 mol / ton of polyester resin P1 Polyester resin containing P1 to 3.0 mol / ton of polyester metal phosphate and 0.4 to 1.5 times the amount of alkali metal phosphate. A polyester film containing 0.1 to 99.9 wt% of P1, (b) 0.1 to 2 wt% of a silicon resin containing a polydimethylsiloxane resin, and (c) a wax component. The polyester film according to claim 1, wherein the wax component contains carnauba wax. The polyester film according to claim 1, wherein the polyester resin P1 contains an aromatic polyester. The polyester film according to claim 3, wherein the aromatic polyester contains at least 50% by weight of ethylene terephthalate as a component of the aromatic polyester. The polyester film of claim 1, wherein at least one layer comprises an outer release layer having a food area coverage of about 10% or less as measured according to a food release test. The at least one layer contains (a) 0.1 to 100% by weight of the polyester resin P2, and the polyester resin P2 is crystallizable and different from the polyester resin P1. (B) 0.1 to 100% by weight of non-polyester resin. A heat-sealable layer containing 0.1-15% by weight of anti-lock containing (c) organic or inorganic particles; and (c) a polyester resin having a melting point of at least 20 ° C. below that of the crystalline copolyester resin or the polyester resin P2. The polyester film according to claim 1, further comprising B. The polyester film according to claim 6, further comprising a heat-sealable layer C having the same or substantially the same composition as that of the heat-sealable layer B. The polyester film according to claim 6, further comprising a heat-sealable layer C having a composition different from that of the heat-sealable layer B. The polyester film according to claim 6, wherein the polyester P2 contains an aromatic polyester. The polyester film according to claim 7, wherein the polyester resin P2 contains an aromatic polyester. The polyester film according to claim 6, wherein the polyester resin P2 contains at least 50% by weight of ethylene terephthalate as a constituent component of the polyester resin P2. The polyester film according to claim 7, wherein the polyester resin P2 contains at least 50% by weight of ethylene terephthalate as a constituent component of the polyester resin P2. The polyester film according to claim 6, wherein the polyester resin having a melting point at least 20 ° C. lower than the melting point of the polyester resin P2 contains a butylene terephthalate repeat unit. The polyester film of claim 6, wherein at least one layer comprises an outer release layer having a food area coverage of about 10% or less as measured according to a food release test. The polyester film of claim 7, wherein at least one layer comprises an outer release layer having a food area coverage of about 10% or less as measured according to a food release test. A laminated metal sheet containing the polyester film according to claim 1. A laminated metal sheet containing the polyester film according to claim 6. A laminated metal sheet containing the polyester film according to claim 7. The laminated metal sheet according to claim 15, wherein at least one layer comprises an outer release layer having a food area coverage of about 10% or less as measured according to a food release test. The laminated metal sheet of claim 16, wherein the outer release layer has a food area coverage of about 10% or less, as measured according to a food release test. The laminated metal sheet of claim 17, wherein the outer release layer has a food area coverage of about 10% or less, as measured according to a food release test. The polyester film according to claim 1, wherein the silicone resin has a kinematic viscosity in the range of 10-50 × 106 cm stalk at room temperature. The polyester film according to claim 1, wherein the amount of the wax component is 0.01 to 0.09% by weight. Polyester film, (a) 0.1-99.9% by weight of polyester resin P1 containing alkali metal phosphate and phosphate; and (b) 0.1-2% by weight of silicone resin; polyester film contains bisphenol A No; where the relative crystallinity value (count per second) measured by XRD (X-ray diffraction test) measured at different positions on the polyester film after steel lamination at the given lamination and post-bake temperature settings. A polyester film containing at least one layer containing a polyester film, which is lower than the value of a film containing no wax component. The polyester film according to claim 24, wherein the alkali metal phosphate is a 1.3 mol / ton polyester resin P1 having an amount of the polyester resin P1 to 3.0 mol / ton. The polyester film according to claim 24, wherein the amount of phosphoric acid is 0.4 to 1.5 times that of alkali metal phosphate. The polyester film according to claim 24, wherein the silicone resin comprises a polydimethylsiloxane resin. The polyester film of claim 24, wherein at least one layer further comprises a wax component. The polyester film according to claim 28, wherein the wax component contains a wax. The polyester film according to claim 29, wherein the wax component contains carnauba wax. The polyester film according to claim 24, wherein the amount of the wax component is 0.01 to 0.09% by weight. Relative crystallinity values (per second) measured by XRD (X-ray crystallography) where at least one layer is measured at different locations on the polyester film after steel lamination at a given lamination and postbake temperature setting. The polyester film according to claim 24, which comprises a material whose count) is lower than the value of the film containing no wax component.

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