Flexible multilayer sealing material and use thereof

Abstract

The present invention relates to a flexible multilayer sealing material, wherein a first layer is a heat sealable layer comprising a copolyester of an aromatic dicarboxylic acid with an aliphatic diol and a cycloaliphatic diol and the first layer is the outermost layer of the flexible multilayer sealing material. The heat sealable layer further comprises an additive, the additive comprising an antiblock agent and / or a slip aid. The flexible multilayer sealing material further comprises a second layer adjacent to the heat sealable layer comprising a copolyester of an aromatic dicarboxylic acid with an aliphatic diol and a cycloaliphatic diol, the second layer comprising or consisting of an ethylene-polar ethylene copolymer. The present invention further provides a sealing material-container assembly, the assembly comprising the sealing material of the present invention and a container to be sealed.

Description

Technical Field

[0001] This invention relates to the field of packaging, and more specifically, to a flexible multilayer sealing material and its applications. Background Technology

[0002] As is well known, polyethylene terephthalate (PET) is a common container material used in food packaging. When sealing PET containers, an additional material such as polyethylene (PE) is usually applied to the sealing area to achieve a heat seal with sufficient strength. Without this additional material, satisfactory seal strength cannot be achieved, especially when the sealing area is contaminated with oil.

[0003] Therefore, there is still an urgent need for a flexible sealing material that can directly heat-seal the sealing parts of PET containers without additional materials, and whose sealing strength meets certain customized requirements, especially when the sealing parts are contaminated with oil. Summary of the Invention

[0004] To address the aforementioned technical problems, in one aspect, the present invention provides a flexible multilayer sealing material, characterized in that the flexible multilayer sealing material comprises a heat-sealable layer (i.e., a first layer) and an optional but preferred controllable adhesive layer (i.e., a second layer). The first layer is a heat-sealable layer comprising a copolyester of an aromatic dicarboxylic acid, an aliphatic diol, and a cycloaliphatic diol, and the first layer is the outermost layer of the flexible multilayer sealing material. The second layer is an adhesive layer comprising an ethylene-polar ethylene copolymer or an adhesive layer composed of an ethylene-polar ethylene copolymer. Its characteristic lies in achieving the required sealing strength by controlling the peel force between the first layer (heat-sealable layer) and the second layer (adhesive layer). In another aspect, the present invention also provides a sealing material-container assembly, the assembly comprising the aforementioned sealing material and a container to be sealed, wherein the sealing portion of the container to be sealed is made of polyethylene terephthalate (PET) material, wherein the sealing material and the sealing portion of the container can achieve sealing through direct contact under heating conditions, forming an easy-to-open packaging. The sealing strength can be adjusted as needed. The maximum sealing strength is not greater than 20N / 15mm, preferably not greater than 18N / 15mm, and not less than 10N / 15mm, preferably not less than 12N / 15mm. The maximum sealing strength is determined according to ASTM F88 / F88M. Detailed Implementation Plan

[0005] The term "direct" as used herein, such as "directly heat-sealed to," "directly adjacent to," and "directly in contact with," is intended to emphasize that there is no third party between the two referred subjects. When referring to two layers, "adjacent to" as used herein is intended to mean two layers directly bonded to each other. In contrast, when applied to a membrane layer indicated as being between two other specified layers, the term "between" includes two cases: the subject layer is directly bonded to the two other layers between which the subject layer is located, and it is not directly bonded to one or both of the two other layers between which the subject layer is located; that is, one or more additional layers may be applied between the subject layer and one or more layers between which the subject layer is located.

[0006] In a first aspect, the present invention provides a flexible multilayer sealing material, characterized in that the first layer of the flexible multilayer sealing material is a heat-sealable layer comprising a copolyester of an aromatic dicarboxylic acid, an aliphatic diol, and a cycloaliphatic diol, and the first layer is the outermost layer of the flexible multilayer sealing material.

[0007] In some embodiments, the aromatic dicarboxylic acid is selected from terephthalic acid, isophthalic acid, phthalic acid, 2,5-, 2,6-, 2,7-naphthalenedicarboxylic acid and mixtures thereof; the aliphatic diol is selected from ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol and mixtures thereof; and the cycloaliphatic diol is selected from 1,3-cyclohexanediethanol, 1,4-cyclohexanediethanol and mixtures thereof.

[0008] In some embodiments, the copolyester of aromatic dicarboxylic acids with aliphatic and cycloaliphatic diols is a copolyester of terephthalic acid with aliphatic and cycloaliphatic diols, particularly a copolyester of terephthalic acid with ethylene glycol and 1,4-cyclohexanediethanol.

[0009] In some embodiments, in the copolyester described above, the amount of aromatic dicarboxylic acid is 100 parts by molar amount, the amount of aliphatic diol is 50-90 parts, and the amount of cyclic aliphatic diol is 10-50 parts.

[0010] In some embodiments, in the copolyester of terephthalic acid with ethylene glycol and 1,4-cyclohexanediethanol, the amount of terephthalic acid is 100 moles, the amount of ethylene glycol is 10-90, 20-80, 30-70, or 60-70 parts, and the amount of 1,4-cyclohexanediethanol is correspondingly 90-10, 80-20, 70-30, or 40-30 parts.

[0011] In some embodiments, the copolyester of aromatic dicarboxylic acids with aliphatic diols and cycloaliphatic diols is PETG sold by Eastman. 6763.

[0012] In some embodiments, the heat-sealable layer of the copolyester comprising aromatic dicarboxylic acids and aliphatic and cyclic aliphatic diols further includes additives, including antiblocking agents and / or slip aids; wherein the antiblocking agent is inorganic and / or organic particles, such as alumina, amorphous silica, talc, carbon black, titanium dioxide, kaolin, or cross-linked polystyrene particles or cross-linked polymer particles based on acrylic derivatives, metal salts such as lithium, calcium, magnesium, barium, zinc, or manganese salts, such as lithium phosphate, lithium fluoride, calcium carbonate, calcium phosphate, calcium sulfate, magnesium carbonate, magnesium phosphate, barium carbonate, and barium sulfate. Representative examples of slip aids include aliphatic or fatty acid amides, such as monounsaturated C18-C22 fatty amides, such as erucamide and oleamide; or low molecular weight amides and fluorinated elastomers.

[0013] In some embodiments, based on the total weight of the first layer, the content of the copolyester of aromatic dicarboxylic acid with aliphatic diol and cycloaliphatic diol is 90-99 wt%, preferably 95-99 wt%; and the content of additives is 1-10 wt%, preferably 1-5 wt%.

[0014] In some embodiments, the flexible multilayer sealing material includes a second layer adjacent to a heat-sealable layer comprising a copolyester containing aromatic dicarboxylic acids, aliphatic diols, and cyclic aliphatic diols.

[0015] The second layer comprises or is composed of an ethylene-polar ethylene copolymer.

[0016] Polar ethylene refers to a monomer unit composed of ethylene units and one or more polar groups; ethylene-polar ethylene copolymers consist of pure ethylene units and polar ethylene units corresponding to the following formula:

[0017]

[0018] R1 is a C1-C3-alkoxycarbonyl group or

[0019] -CO-OR4, where

[0020] R4 is hydrogen; or

[0021] C1-C of straight or branched chains 18 -alkyl group, optionally mono, di, tri, or polysubstituted with OH or phenyl groups; or

[0022] C5-C 12 -Cycloalkyl, optionally bridged by a C1-C3 bridge and optionally mono-, di-, tri-, or poly-substituted by a C1-C6 alkyl group; or

[0023] phenyl; or

[0024] -(CH2-CH2-O) q -R5, where R5 is hydrogen, C1-C 24 -alkyl or phenyl, wherein the phenyl group is optionally C1-C2. 12 -Alkyl mono, di, or polysubstituted; q is

[0025] -(CH2-CH2-O) q - The degree of polymerization in the R5 part,

[0026] R2 is hydrogen or a C1-C6 alkyl group, and

[0027] R3 is -COOR6 or hydrogen, where R6 is hydrogen or a C1-C6 alkyl group, and

[0028] n and m are the same or different integers, where the sum of n+m corresponds to the degree of polymerization of the ethylene-polar ethylene copolymer.

[0029] Preferably,

[0030] R1 is a methoxycarbonyl group or

[0031] -CO-OR4, where

[0032] R4 is hydrogen; or

[0033] C1-C of straight or branched chains 18 -alkyl group, optionally mono- or tri-substituted with OH and / or mono-substituted with phenyl; or

[0034] C5-C6 cycloalkyl groups, optionally bridged by a C1 bridge and optionally mono-, di-, tri-, or poly-substituted by C1-C6 alkyl groups; or

[0035] phenyl; or

[0036] -(CH2-CH2-O) q -R5, where R5 is hydrogen, C1-C4-alkyl, or phenyl, wherein the phenyl is optionally C7-C6-alkyl. 12 -Alkyl mono, di, or polysubstituted; q is -(CH2-CH2-O) q - The degree of polymerization in the R5 part,

[0037] R2 is hydrogen or methyl, and

[0038] R3 is -COOR6 or hydrogen, where R6 is hydrogen or a C1-C6 alkyl group, and

[0039] n and m are the same or different integers, where the sum of n+m corresponds to the degree of polymerization of the ethylene-polar ethylene copolymer.

[0040] Examples of these polar ethylene monomers or polar ethylene repeating units include: vinyl acetate, acrylic acid, methacrylic acid, ethyl acrylate, ethyl methacrylate, methyl acrylate, methyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, 2-octyl acrylate, 2-octyl methacrylate, undecyl acrylate, undecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, dodecyl acrylate, dodecyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isobornyl acrylate, methacrylate Isoborneol ester, cyclohexyl acrylate, cyclohexyl methacrylate, benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, poly(ethylene glycol) acrylate, poly(ethylene glycol) methacrylate, poly(ethylene glycol) methyl ether acrylate, poly(ethylene glycol) methyl ether methacrylate, poly(ethylene glycol) docosyl ether acrylate, poly(ethylene glycol) docosyl ether methacrylate, poly(ethylene glycol) 4-nonylphenyl ether acrylate, poly(ethylene glycol) 4-nonylphenyl ether methacrylate, poly(ethylene glycol) phenyl ether acrylate, poly(ethylene glycol) phenyl ether methacrylate, dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, and dibutyl fumarate.

[0041] In some embodiments, the second layer comprises ethylene methyl acrylate (EMA) or is composed of EMA.

[0042] In some implementations, the second layer consists of EMA.

[0043] In some embodiments, the ethylene-polar ethylene copolymer is an ethylene-methyl acrylate copolymer (EMA), preferably, the proportion of repeating methyl acrylate (MA) units is 10 to 90 mol%, preferably 20 to 80 mol%, more preferably 20 to 30 mol%, for example 24 mol%.

[0044] In some embodiments, the proportion of polar ethylene repeating units in the ethylene-polar ethylene copolymer is 1 to 99 mol%, for example 10 to 90 mol%, or 20 to 80 mol%.

[0045] In some embodiments, the proportion of methyl acrylate units in the ethylene-methyl acrylate copolymer is 1 to 99 mol%, for example 10 to 90 mol%, or 20 to 80 mol%.

[0046] In some embodiments, the flexible multilayer sealing material further includes a third layer, which is a base layer, and the flexible multilayer sealing material optionally includes a fourth layer, which is a tie layer; wherein, in the absence of a fourth layer, the third layer is directly adjacent to the second layer, or in the presence of a fourth layer, the fourth layer is sandwiched between the second and third layers.

[0047] In some embodiments, the base layer, which serves as the third layer, can be a single-layer or multi-layer structure composed of one or more of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), ethylene-vinyl alcohol copolymer (EVOH), and nylon.

[0048] In some implementations, based on the total weight of the first, second, and third layers, the weight of the first layer accounts for 2-20% by weight, the weight of the second layer accounts for 3-30% by weight, and the weight of the third layer accounts for 50-95% by weight; for example, the weight of the first layer accounts for 5-10% by weight, the weight of the second layer accounts for 15% by weight, and the weight of the third layer accounts for 85-75% by weight.

[0049] One or more of the above embodiments of the present invention can be appropriately combined to constitute a new technical solution, and the resulting new technical solution is also considered to be part of the disclosure of this specification.

[0050] In a second aspect, the present invention also provides a sealing material-container assembly, the assembly comprising the aforementioned sealing material and a container to be sealed, wherein the sealing portion of the container to be sealed is made of polyethylene terephthalate (PET) material, wherein the sealing material and the sealing portion of the container can achieve a seal through direct contact under heating conditions, forming an easy-open method for end users to open the packaging. The maximum sealing strength is not greater than 20 N / 15 mm, preferably not greater than 18 N / 15 mm, and not less than 10 N / 15 mm, preferably not less than 12 N / 15 mm, and the maximum sealing strength is determined according to ASTM F88 / F88M.

[0051] In some embodiments, the sealing portion of the container to be sealed is made of crystalline PET (c-PET) material, amorphous PET (a-PET) material, or combinations thereof.

[0052] In some embodiments, the sealing portion of the container to be sealed is made of amorphous PET (a-PET) material.

[0053] In some embodiments, the container to be sealed is made entirely of crystalline PET (c-PET), amorphous PET (a-PET), or combinations thereof.

[0054] In some implementations, the container to be sealed is made entirely of amorphous PET (a-PET) material.

[0055] In some embodiments, the sealing material-container assembly further includes a food product located within the container to be sealed, the food product comprising oils, for example, an oil content of 0.01-100 wt%, such as 0.1-99 wt%, such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, 99 wt%, or any two of these numerical ranges, based on the weight of the food product. The oils and fats mentioned include, but are not limited to, tea oil, bitter tea oil, camellia oil, soybean oil, deep-sea shark liver oil, cod liver oil, shea butter, avocado oil, canola oil, sunflower oil, chicken oil, whale oil, rice bran oil, cocoa butter, soybean salad oil, virgin olive oil, light olive oil, low-acidity cold-pressed virgin olive oil, olive oil, cold-pressed virgin olive oil, extra virgin olive oil, palm oil, sesame oil, rice bran oil, corn oil, corn oil, emu oil, mustard oil, butter, beef tallow, almond oil, apricot kernel oil, peanut oil, shortening, walnut oil, roast duck oil, wheat germ oil, corn germ oil, skunk oil, crocodile oil, fish oil, lard, flaxseed oil, coconut oil, hazelnut oil, safflower seed oil, canola seed oil, sunflower seed oil, cold-pressed flaxseed oil, edible cottonseed oil, tomato seed oil, poppy seed oil, and grape seed oil.

[0056] One or more of the above embodiments of the present invention can be appropriately combined to constitute a new technical solution, and the resulting new technical solution is also considered to be part of the disclosure of this specification.

[0057] In a third aspect, the present invention also provides a method for manufacturing the flexible multilayer sealing material of the present invention, wherein the flexible multilayer sealing material can be manufactured by a blow molding process, a flat-cast process, or a round-cast process.

[0058] In a fourth aspect, the present invention also provides the use of the flexible multilayer sealing material of the present invention in the application as a non-forming web, lid stock, tray liner, forming web, vertical form fill seal roll stock (VFFS rollstock) and / or horizontal form fill seal roll stock (HFFS rollstock), pouches, bags, overwrap, flow wrap, etc.

[0059] The flexible multilayer sealing material of the present invention can provide excellent performance and functionality in the following aspects: lock-down sealing relative to itself or sealing materials containing PET or PETG (a copolyester of terephthalic acid, ethylene glycol and 1,4-cyclohexanediethanol), anti-fogging, barrier, optical properties (gloss, transparency and haze), strength, stiffness or modulus, and connectivity.

[0060] Example

[0061] The technical solution and its effects of the present invention are illustrated below through examples. It should be understood that the scope of protection of the present invention is not limited to the examples described.

[0062] Sample composition

[0063] Example 1

[0064] The sample of Example 1 consists of a three-layer structure. The first layer is a heat-sealable layer comprising 97% by weight of PETG (a copolyester produced from three monomers: terephthalic acid (TPA), ethylene glycol (EG), and 1,4-cyclohexanediethanol (CHDM), obtained from Eastman) and 3% by weight of additives (an amorphous silica concentrate with polyester resin as a carrier, obtained from SUKANO). The second layer is an ethylene-methyl acrylate (EMA) layer, wherein the EMA copolymer contains 24% by weight of MA (ethylene-methyl acrylate copolymer, obtained from Dow Chemical). The third layer is a base layer composed of linear low-density polyethylene (LLDPE). The first layer accounts for 10% by weight of the total weight of the three-layer structure, the second layer accounts for 15% by weight, and the first layer accounts for 75% by weight.

[0065] Examples 2 and 3

[0066] The samples of Examples 2 and 3 consist of a 3-layer structure, constructed in a manner similar to that of Example 1. The specific structural composition of the samples of Examples 2 and 3 is listed in the table below.

[0067] Comparative Example 1

[0068] The sample of Comparative Example 1 consists of a three-layer structure, where the first sealing layer is a modified EMA copolymer (a commercially available sealing material), and the second and third layers are both LLDPE. The structural composition of the sample of Comparative Example 1 is listed in the table below.

[0069] Sample of Example 1

[0070]

[0071] Sample of Example 2

[0072]

[0073] Sample of Example 3

[0074]

[0075] Sample of Comparative Example 1

[0076]

[0077] Sample preparation

[0078] Example Sample Preparation

[0079] Several extruders are used to supply different molten material flows, which are then combined and co-extruded into a cylindrical film in a composite die. After inflation and cooling by an air ring, a multi-layer composite structure is obtained. After the cylindrical film is trimmed, it is wound into two rolls of film with a total thickness of 50 μm. The rolls consist of a first sealing layer of PETG with a slip and anti-stick agent, a second layer of EMA, and a third base layer of LLDPE. This film is then laminated with biaxially oriented polyester film using an adhesive bonding process and used as a sealing cap for containers to be sealed.

[0080] Comparative sample preparation

[0081] The preparation process is the same as that of the sample in the example, but the first layer is a modified EMA copolymer, and the second and third layers are both LLDPE.

[0082] Sample testing

[0083] Using a Multivac R245 food packaging machine, various sealing material samples were heat-sealed onto the sealing portion of a container made of a-PET. The heat-sealing conditions used were as follows:

[0084] Sealing temperature: 150-165℃

[0085] Sealing pressure: 0.40-0.50MPa

[0086] Sealing time: 1.0-1.5 seconds

[0087] To investigate the impact of potential grease contamination at the sealing points on the sealing strength during actual packaging, a simulated sample was prepared as follows.

[0088] Wearing food-grade rubber gloves, manually apply a simulated mixture of oils (chili oil, vegetable blended oil, animal oil) to the sealing area to achieve a seal.

[0089] The seal strength was tested according to ASTM F88 / F88M. The results are listed in Table A below.

[0090] After the specimen is prepared, it is tested in a tensile testing machine.

[0091] Tensile testing machine: INSTRON 5943

[0092] Tension sensor: 100N

[0093] Starting distance between fixtures: 50mm

[0094] Test speed: 300 mm / min

[0095] Sample peeling angle: 180°

[0096] Table A: Sealing Strength Test Results

[0097]

Claims

1. A flexible multilayer sealing material, characterized in that The first layer of the flexible multilayer sealing material is a heat-sealable layer comprising a copolyester of an aromatic dicarboxylic acid with an aliphatic diol and a cycloaliphatic diol, and the first layer is the outermost layer of the flexible multilayer sealing material; The flexible multilayer sealing material comprises a second layer adjacent to the heat-sealable layer comprising a copolyester of an aromatic dicarboxylic acid with an aliphatic diol and a cycloaliphatic diol, the second layer consisting of an ethylene-polar ethylene copolymer.

2. The flexible multilayer sealing material according to claim 1, characterized in that The copolyester of an aromatic dicarboxylic acid with an aliphatic diol and a cycloaliphatic diol is a copolyester of terephthalic acid with ethylene glycol and 1,4-cyclohexane dimethanol, wherein the fraction of terephthalic acid is 100 parts by mole, the fraction of ethylene glycol is 60-70 parts by mole, and the fraction of 1,4-cyclohexane dimethanol is 30-40 parts by mole.

3. The flexible multilayer sealing material according to claim 1 or 2, characterized in that The heat-sealable layer comprising a copolyester of an aromatic dicarboxylic acid with an aliphatic diol and a cycloaliphatic diol further comprises an additive, the additive comprising an antiblock agent and / or a slip aid.

4. The flexible multilayer sealing material according to claim 1 or 2, characterized in that The content of the copolyester of an aromatic dicarboxylic acid with an aliphatic diol and a cycloaliphatic diol is 90-99 wt% based on the total weight of the first layer; the content of the additive is 1-10 wt%.

5. The flexible multilayer sealing material according to claim 1 or 2, characterized in that The content of the copolyester of an aromatic dicarboxylic acid with an aliphatic diol and a cycloaliphatic diol is 95-99 wt% based on the total weight of the first layer; the content of the additive is 1-5 wt%.

6. The flexible multilayer sealing material according to claim 1 or 2, characterized in that The second layer consists of an ethylene-methyl acrylate (EMA).

7. The flexible multilayer sealing material according to claim 1 or 2, wherein In the ethylene-polar ethylene copolymer, the proportion of polar ethylene repeating units is 1 to 99 mole%.

8. The flexible multilayer sealing material according to claim 1 or 2, wherein In the ethylene-polar ethylene copolymer, the proportion of polar ethylene repeating units is 20 to 80 mole%.

9. The flexible multilayer sealing material according to claim 6, wherein In the ethylene-methyl acrylate copolymer, the proportion of methyl acrylate units is 20 to 80 mole%.

10. The flexible multilayer sealing material according to claim 1 or 2, characterized in that The flexible multilayer sealing material further comprises a third layer, the third layer being a base layer, and the flexible multilayer sealing material optionally comprises a fourth layer, the fourth layer being a tie layer; wherein in the absence of the fourth layer, the third layer is directly adjacent to the second layer, or in the presence of the fourth layer, the fourth layer is sandwiched between the second layer and the third layer.

11. The flexible multilayer sealing material according to claim 10, characterized in that The base layer as the third layer is a single layer or a multi-layer structure consisting of one or more of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), ethylene-vinyl alcohol copolymer (EVOH), and Nylon.

12. The flexible multilayer sealing material of claim 10, wherein The base layer as the third layer consists of linear low-density polyethylene (LLDPE).

13. The flexible multilayer sealing material of claim 10, wherein The weight of the first layer accounts for 2-20 wt% based on the total weight of the first layer, the second layer accounts for 3-30 wt%, and the third layer accounts for 50-95 wt%.

14. The flexible multilayer sealing material of claim 10, wherein The first layer has a weight of 5-10 wt%, the second layer has a weight of 15 wt%, and the third layer has a weight of 85-75 wt%, based on the total weight of the first, second and third layers.

15. A sealed material-container assembly, said assembly comprising a flexible multilayer sealing material according to any one of the preceding claims and a container to be sealed, characterized in that The sealing site of the container to be sealed is composed of a polyethylene terephthalate (PET) material; wherein the sealing material and the sealing site of the container can be sealed by direct contact under heating conditions, the maximum sealing strength is not more than 20 N / 15 mm, and not less than 10 N / 15 mm, the maximum sealing strength is determined according to ASTM F88 / F88M.

16. The material-container assembly of claim 15, wherein The sealing material and the sealing site of the container can be sealed by direct contact under heating conditions, the maximum sealing strength is not more than 18 N / 15 mm, and not less than 12 N / 15 mm, the maximum sealing strength is determined according to ASTM F88 / F88M.

17. The sealant-container assembly of claim 15, wherein The polyethylene terephthalate (PET) material is amorphous PET (a-PET) material.

18. The sealing material-container assembly of claim 15, further comprising a food product in the container to be sealed, the food product comprising oil and fat.

19. The sealant-container assembly of claim 18, wherein The content of oil and fat is 0.1-100 wt%, based on the weight of the food product.

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