JP2019010814A - Food packaging film for boil treatment, bottom material for deep contraction packaged body, and deep contraction packaged body - Google Patents

Abstract

To provide a food packaging film for boil treatment having resistance to a boil treatment, capable of preventing curl during the boil treatment, and further having good deep contraction moldability.SOLUTION: There is provided a film for food packaging for boil treatment constituted by 3 layers of an outermost layer, an intermediate layer and an innermost layer, in which a resin component constituting the outermost layer mainly contains a heat resistant polyester resin having following a) and b) properties and glass transition point (Tg) of 90°C or more, and total thickness is 10 μm to 80 μm. a) crystal melting calorie ▵Hm during temperature rise at temperature rise rate of 10°C/min. according to JIS-K7121 by a differential scanning type calorimeter is 20 J/g or less. b) it consists of 2 or more kinds of diol components, and at least one kid of the diol components has a cyclic structure containing no double bond.SELECTED DRAWING: None

Description

  The present invention relates to a food packaging film for boil treatment that can be suitably used for a deep-drawn package having a shallow molding depth for wrapping thin contents such as sliced ham and sliced bacon that are boiled after packaging. The present invention relates to a bottom material for a deep-drawn packaging body using the above and a deep-drawing packaging body using the bottom material.

  Conventionally, as a deep drawing packaging film for slicing ham, sliced bacon, etc., polyethylene terephthalate glycol resin (PETG) is used for the outer layer, nylon (Ny) and ethylene-vinyl acetate copolymer saponified product (EVOH) are used for the intermediate layer. And the composite film which has a cohesive failure type easy peel layer in a seal layer is used widely widely (for example, patent documents 1-3).

JP 04-259547 JP 07-001544 A JP 10-086284 A

  However, when the PETG resin is used as the outer layer, the Tg of the PETG resin is as low as 82 ° C. with respect to the boil processing temperature of 98 ° C. during the boil processing, which causes problems that the outer layer surface becomes rough or the outer layers are fused.

  In addition, in the case of a film configuration with a polyamide resin as an outer layer, which is generally used for deep-draw packaging of processed foods such as hamburgers and chicken, and contents that require boil processing such as side dishes, There has been a problem that the polyamide resin absorbs moisture and tends to curl and deteriorate the appearance.

  Furthermore, for the film structure in which PP that is difficult to absorb moisture is arranged in the outer layer to suppress curling during the boil processing, which is used for deep drawing packaging of contents that require boil processing such as processed foods and prepared dishes. There was a problem that moldability was poor.

  In view of the above problems, the present invention provides a food packaging film for boil treatment that has resistance to boil treatment, can suppress curling during boil treatment, and has good deep drawability. Is an issue.

  As a result of intensive studies, the present inventors have succeeded in obtaining a heat-shrinkable laminated porous film that can solve the above-mentioned problems of the prior art, and have completed the present invention. That is, the present invention is as follows.

The first aspect of the present invention is a food packaging film for boil treatment composed of at least three layers of an outermost layer, an intermediate layer, and an innermost layer, wherein the resin component constituting the outermost layer is a) and It is a food packaging film for boil treatment having a total thickness of 10 μm or more and 80 μm or less, which is mainly composed of a heat-resistant polyester resin having the characteristics of b) and having a glass transition point (Tg) of 90 ° C. or more.
a) In accordance with JIS-K7121, a crystal scanning calorie ΔHm at the time of temperature increase at a temperature increase rate of 10 ° C./min with a differential scanning calorimeter is 20 J / g or less,
b) It consists of two or more types of diol components, and at least one type of diol component has a cyclic structure that does not contain a double bond.

  Here, the “main component” is based on the entire resin component constituting the outermost layer (100% by mass), preferably a heat-resistant polyester resin, preferably 50% by mass or more, more preferably 80% by mass or more, and still more preferably. Means 95% by mass or more, particularly preferably 100% by mass.

  In the first embodiment, the thickness of the outermost layer is preferably 10% or more and 60% or less of the total thickness.

  In the first aspect, the intermediate layer is preferably a polyamide resin layer or a multilayer including a polyamide resin layer and an ethylene-vinyl acetate copolymer saponified resin layer.

  In the first embodiment, the innermost layer is preferably a heat seal resin layer.

  The 2nd form of this invention is the bottom material for deep-drawing packaging bodies formed with the food packaging film for boil processing of a 1st form.

  The 3rd form of this invention is a deep drawing package using the bottom material for deep drawing packages of the 2nd form.

  The food packaging film for boil treatment of the present invention has resistance to boil treatment, can suppress curling during boil treatment, and has good deep drawability.

<Boiled food packaging film>
(Outermost layer)
The heat-resistant polyester resin constituting the outermost layer is a polyester resin according to JIS-K7121, and has a heat of crystal melting ΔHm of 20 J / g or less at a temperature rising rate of 10 ° C./min with a differential scanning calorimeter. It is a resin and uses two or more kinds of diol components. At least one of these diol components is preferably a relatively bulky diol having a cyclic structure in the molecule. The cyclic structure is preferably a cyclic structure not including a double bond, and may contain an oxygen atom derived from an ether bond in the molecule.

  Examples of such bulky diol components include spiroglycol, tetramethylcyclobutanediol (hereinafter sometimes abbreviated as TMCD), tricyclodecane dimethanol, isosorbide and the like. Among these, spiroglycol, TMCD, and isosorbide are particularly suitable because they can increase the glass transition temperature of the heat-resistant polyester resin and increase the heat resistance of the boiled food packaging film of the present invention by using it as a diol component. is there.

  Examples of the diol component other than the bulky diol component in the heat resistant polyester resin include diethylene glycol, ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3- Propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol, cyclohexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol , P-xylenediol, bisphenol A, tetrabromobisphenol A, tetrabromobisphenol A-bis (2-hydroxyethyl ether), and the like. Among these, ethylene glycol is preferable because it is industrially inexpensive and easy to control crystallinity and glass transition temperature. 1,3-cyclohexanedimethanol does not increase the glass transition temperature of the heat-resistant polyester resin, but is preferable because it can improve the impact resistance and transparency of the heat-resistant polyester resin.

  The content ratio of the bulky diol component in the heat-resistant polyester resin is preferably 20 mol% or more, more preferably 30 mol% or more with respect to the total diol components contained in the heat-resistant polyester resin. It is preferably 40 mol% or more, particularly preferably. Further, the upper limit of the content ratio of the bulky diol component is not particularly limited, but it is preferably 70 mol% or less because there is no possibility of problems such as loss of fluidity at the time of melting. When the lower limit of the content ratio of the bulky diol component is 20 mol% or more, the glass transition temperature of the heat-resistant polyester resin can be increased, and heat resistance can be imparted to the boiled food packaging film of the present invention.

  Examples of the dicarboxylic acid component used in the heat-resistant polyester resin include terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2,5-dichloroterephthalic acid, 2-methylterephthalic acid, 4,4-stilbene dicarboxylic acid, 4 , 4-biphenyldicarboxylic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4-diphenyl ether dicarboxylic acid, 4,4 -Aromatic dicarboxylic acids such as diphenoxyethanedicarboxylic acid, 5-Na sulfoisophthalic acid, ethylene-bis-p-benzoic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, 1,3-cyclohexanedicarboxylic acid, Fats such as 1,4-cyclohexanedicarboxylic acid Family dicarboxylic acid components. These dicarboxylic acid components may be used alone or in admixture of two or more. In the present invention, terephthalic acid and isophthalic acid are particularly preferred as the dicarboxylic acid because it is industrially inexpensive and the synthesized heat-resistant polyester resin is chemically stable.

  The intrinsic viscosity (IV) of the heat-resistant polyester resin is not particularly limited, but is usually 0.4 dl / g or more and 1.0 dl / g or less, and 0.5 dl / g or more and 0.9 or less. preferable. If the intrinsic viscosity (IV) is in the above range, it is preferable because both the mechanical strength of the film and the fluidity at the time of melting can be achieved.

  The glass transition temperature of the heat-resistant polyester resin is measured by a differential scanning calorimeter according to JIS-K7121, and the lower limit needs to be 90 ° C. or higher, more preferably 95 ° C. or higher, more preferably 100 ° C. or higher. It is. Moreover, although the upper limit of glass transition temperature is not specifically limited, Usually, it is 130 degrees C or less. If the glass transition temperature of the heat-resistant polyester resin is less than 90 ° C., the food packaging film for boil treatment lacks heat resistance during the boil treatment, which is not preferable. The glass transition temperature of the heat-resistant polyester resin can be adjusted to a preferable range by adjusting the copolymerization component.

  The heat-resistant polyester resin is required to have a crystal melting heat ΔHm at the time of temperature increase of 20 J / g or less at a temperature increase rate of 10 ° C./min with a differential scanning calorimeter in accordance with JIS-K7121. Preferably it is 15 J / g or less, More preferably, it is 10 J / g or less, Most preferably, it is 5 J / g. When the heat of crystallization and fusion ΔHm of the heat-resistant polyester resin exceeds 20 J / g, the transparency is lowered due to crystallization or the moldability is deteriorated.

  As the heat-resistant polyester resin, various commercially available raw materials can be preferably used. For example, trade name: “ALTERSTER” (manufactured by Mitsubishi Gas Chemical Co., Ltd., spiroglycol copolymer polyester resin), trade name: “TRITAN” ( EASTMAN Chemical, TMCD copolymer polyester resin), and the like.

  The resin component constituting the outermost layer is mainly composed of the above heat-resistant polyester resin. Here, the “main component” is based on the entire resin component constituting the outermost layer (100% by mass), preferably a heat-resistant polyester resin, preferably 50% by mass or more, more preferably 80% by mass or more, and still more preferably. Means 95% by mass or more, particularly preferably 100% by mass.

  Further, the thickness of the outermost layer is not particularly limited, but the lower limit is preferably 5% or more, more preferably 8% or more, still more preferably 10% or more with respect to the total thickness, and The upper limit is preferably 60% or less, more preferably 50% or less, and still more preferably 40% or less. If the thickness is 5% or more, curling at the flange part of the package and pinhole generation at low temperatures can be suppressed, good appearance and pinhole resistance at low temperatures can be obtained, and the upper limit is 60% By doing so, good deep drawability can be maintained.

  The thickness of the outermost layer is 30 μm, more preferably 20 μm from the viewpoint of cost and film-forming property, and 2 μm, more preferably 3 μm, from the viewpoint of heat resistance during boil sterilization.

(Middle layer)
The intermediate layer may be a single polyamide resin layer or a multilayer structure including a polyamide resin layer and an ethylene-vinyl acetate copolymer saponified resin layer. Further, an adhesive layer described later may be provided between the polyamide resin layer and the ethylene-vinyl acetate copolymer saponified resin layer.

  The polyamide resin used for the intermediate layer has a function of imparting pinhole resistance, oxygen barrier property, deep drawability and the like, specifically 6-nylon (6Ny) generally called nylon, 66-nylon (66Ny), 6-66 nylon (6-66Ny), 12-nylon (12Ny), MXD6 nylon obtained by polycondensation of metaxylenediamine and adipic acid (MXD6Ny), and blends thereof. It can be used and is appropriately selected from these according to the purpose of use. For example, 6Ny or 6-66Ny is preferable when deep drawability is required. When high oxygen barrier properties are required, MXD6Ny or a blend of MXD6Ny and 6Ny, and further, in addition to the polyamide resin layer, ethylene-acetic acid is used. A vinyl copolymerized saponified product (EVOH) layer can also be provided. The polyamide resin layer may be a single layer or a laminated layer made of these polyamide resins according to the required quality.

  The lower limit of the thickness of the polyamide resin (PA) layer is preferably 2 μm or more, and more preferably 5 μm or more. The upper limit is preferably 30 μm or less, and more preferably 20 μm or less. By setting the lower limit to 2 μm or more, good deep drawability can be maintained, and by setting the upper limit to 30 μm or less, the occurrence of curling at the flange portion of the package can be suppressed and a good appearance can be obtained. .

  The thickness of the EVOH layer is not particularly limited, but the lower limit is 2 μm or more, preferably 3 μm or more, and 30 μm or less, preferably 20 μm or less. By setting the lower limit of the EVOH layer thickness to 2 μm, sufficient oxygen barrier properties can be obtained, and by setting the upper limit to 30 μm, the coextrudability of the film is not deteriorated and good film strength can be obtained. Can hold.

(Innermost layer)
The innermost layer can be a heat seal resin layer.
The resin constituting the heat seal resin layer is not particularly limited, and general polyethylene resins, cohesive failure type easy peel resins, and the like can be used.
The cohesive failure type easy peel (hereinafter abbreviated as EP) resin is not particularly limited as long as it has a cohesive failure property. Examples of such resins include blends of LLDPE and polybutene, ethylene-vinyl acetate copolymers (hereinafter sometimes abbreviated as EVA) and PP, blends of PP and LDPE, blends of PP and ionomer, PP and Examples thereof include a blend of an ethylene-acrylic acid copolymer (hereinafter sometimes abbreviated as EAA), a blend of PP and an ethylene-methacrylic acid copolymer (hereinafter sometimes abbreviated as EMMA), and the like. Among them, a blend of LLDPE and polybutene, a blend of EVA and PP, or a blend of PP and LDPE can be preferably used.

  The thickness of the EP layer is 2 μm or more, preferably 3 μm or more, more preferably 4 μm or more, and 15 μm or less, preferably 12 μm or less, more preferably 10 μm or less from the viewpoint of film forming properties and peel appearance. Is desirable. By making the thickness of the EP layer 2 μm or more, a stable film-forming property can be obtained, and by making the thickness of the EP layer 15 μm or less, fluffing and film residue can hardly occur during peeling, Good peel appearance can be obtained.

(Adhesive layer)
It is preferable to provide an adhesive layer (polyolefin adhesive resin layer) between the outermost layer and the intermediate layer and between the innermost layer and the intermediate layer. As the polyolefin-based adhesive to be used, a modified polyolefin-based resin grafted with at least one monomer selected from unsaturated carboxylic acid or a derivative thereof can be suitably used. The outer layer, intermediate layer, and innermost layer can be firmly bonded.

(EVA layer and PE layer)
In addition, an ethylene-vinyl acetate copolymer (EVA) layer or a polyethylene (PE) layer can be disposed inside the innermost layer for the purpose of imparting flexibility. Although the ethylene content of EVA is not particularly limited, it is preferably 1.5 mol% or more and 20 mol% or less, preferably 3 mol% or more and 15 mol% or less from the viewpoint of film formation stability. Further preferred.

(Total thickness of food packaging film for boil processing)
The total thickness of the food packaging film for boil treatment of the present invention is preferably 10 μm or more, more preferably 20 μm or more, further preferably 30 μm or more, and the upper limit is preferably 100 μm or less, more preferably 80 μm or less, more preferably 10 μm or more. Preferably it is 70 micrometers or less. By setting the lower limit to 10 μm or more, the rigidity of the film can be increased and curling can be suppressed, and by setting the upper limit to 100 μm or less, good moldability can be imparted to the film.

(Additive)
The food packaging film for boil treatment of the present invention is silica, talc, kaolin, calcium carbonate, etc. for the purpose of improving and adjusting various properties such as moldability and productivity within the range that does not significantly impair the effects of the present invention. Inorganic particles, pigments such as titanium oxide, carbon black, flame retardants, weathering stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, crosslinking agents, lubricants, nucleating agents, plasticizers, anti-aging agents, etc. Additives can be added as appropriate.

(Layer structure of food packaging film for boil treatment)
In the layer structure of the film of the present invention, the outermost layer is a heat-resistant polyester resin layer, and the layer structure of other layers composed of at least three layers including the above layers is not particularly limited.
For example, when expressed as a heat-resistant polyester resin layer (A), PA layer (B), EVOH layer (C), PE layer (D), heat seal layer (E), and adhesive resin layer (F), the following layers A configuration can be formed.
(1) A / F / B / F / E
(2) A / F / B / F / D / E
(3) A / F / B / C / F / E
(4) A / F / B / C / F / D / E
(5) A / F / C / B / F / D / E
(6) A / F / C / B / F / E
(7) A / F / B / C / B / F / D / E
(8) A / F / B / F / D / E
(9) A / F / B / F / C / F / D / E

  Among the above, a preferable layer configuration is (3), (4), (5), or (6), and more preferably (4) or (5).

(Method for producing food packaging film for boil treatment)
The food packaging film for boil treatment of the present invention can be produced using a known method. For example, an extrusion lamination method, a coextrusion inflation method, a coextrusion T die method, and the like can be used, and it is particularly preferable to use a coextrusion T die method.

<Bottom material for deep-drawn package and deep-drawn package>
The food packaging film for boil treatment of the present invention can be used for a deep-drawn package by molding. In particular, when the film of the present invention is used as the bottom material of a deep drawn package, a good deep drawn package can be obtained. The lid of the deep drawn package of the present invention is not particularly limited as long as heat sealability with the film of the present invention can be obtained. For example, a cover material obtained by laminating a stretched polypropylene resin layer, a transparent vapor-deposited polyethylene terephthalate resin, and a linear low density polyethylene (LLDPE) layer, or a stretched polyethylene terephthalate resin and a coextruded film (EVOH, Ny, including LLDPE as a seal layer) Can be mentioned. Moreover, as a deep drawing package of this invention, the film of this invention can also be used for a cover material film and a bottom material film.

  When the film of the present invention is used as a bottom material for a deep drawing package, for example, after the film of the present invention is formed into a desired shape and size using a deep drawing mold (film supply step and film forming step), Filled with contents such as sliced ham and sliced bacon (content filling process), and further sealed with a lid material film (cover material film supply process and sealing process) and vacuum packaged (vacuum packaging process) By cooling (cooling step) and cutting (cutting step), a deep drawn package can be produced.

EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
<Each layer component>
Heat-resistant polyester 1: TMCD copolymer polyester resin (Tg: 116 ° C., ΔHm: 0 J / g),
Heat-resistant polyester 2: Spiroglycol copolymer polyester resin (Tg: 101 ° C., ΔHm: 0 J / g),
Heat-resistant polyester 3: Spiroglycol copolymer polyester resin (Tg: 110 ° C., ΔHm: 0 J / g),
PETG: Polyethylene terephthalate-glycol copolymer (Tg: 82 ° C., ΔHm: 0 J / g),
APET: Polyethylene terephthalate resin [dicarboxylic acid component is terephthalic acid, glycol component is 98 mol% ethylene glycol and 2 mol% diethylene glycol], (Tg: 72 ° C., ΔHm: 30 J / g),
Adhesive resin: unsaturated carboxylic acid modified polyolefin resin,
6Ny: 6 nylon (Tg: 47 ° C),
12Ny: 12 nylon (Tg: 115 ° C),
Co-Ny: 6-66 copolymer nylon (nylon 66 ratio 15%),
PP: random polypropylene (Tg: 115 ° C., ΔHm: 100 J / g),
EVOH1: saponified ethylene-vinyl acetate copolymer (ethylene 38 mol),
EVOH2: Saponified ethylene-vinyl acetate copolymer (ethylene 32 mol),
LL: linear low density polyethylene,
EVA: ethylene-vinyl acetate copolymer,
EP: a mixture of ethylene-vinyl acetate copolymer (50%) and polypropylene (50%),

<Examples 1-9, Comparative Examples 1-12>
A food packaging film for boil treatment having the following layer structure was formed by a coextrusion molding method. “A layer / B layer” means that the A layer and the B layer are laminated.
(Example 1: Total layer thickness: 70 μm)
Heat-resistant polyester 1 / adhesive resin / 6Ny / EVOH1 / adhesive resin / EVA / EP,
Each layer thickness (μm): 10/5/10/5/5/30/5,

(Example 2: Total layer thickness: 50 μm)
Heat-resistant polyester 1 / adhesive resin / co-Ny / EVOH2 / adhesive resin / LL,
Each layer thickness (μm): 8/4/8/4/4/22,

(Example 3: Total layer thickness: 30 μm)
Heat-resistant polyester 1 / adhesive resin / EVOH1 / co-Ny / adhesive resin / EVA / EP,
Each layer thickness (μm): 4/3/3/5/3/9/3,

(Example 4: Total layer thickness: 70 μm)
Heat-resistant polyester 2 / adhesive resin / 6Ny / EVOH1 / adhesive resin / EVA / EP,
Each layer thickness (μm): 10/5/10/5/5/30/5,

(Example 5: Total layer thickness: 50 μm)
Heat-resistant polyester 2 / adhesive resin / co-Ny / EVOH2 / adhesive resin / LL,
Each layer thickness (μm): 8/4/8/4/4/22,

(Example 6: Total layer thickness: 30 μm)
Heat-resistant polyester 2 / adhesive resin / EVOH1 / co-Ny / adhesive resin / EVA / EP,
Each layer thickness (μm): 4/3/3/5/3/9/3,

(Example 7: Total layer thickness: 70 μm)
Heat-resistant polyester 3 / adhesive resin / 6Ny / EVOH1 / adhesive resin / EVA / EP,
Each layer thickness (μm): 10/5/10/5/5/30/5,

(Example 8: Total layer thickness: 50 μm)
Heat-resistant polyester 3 / adhesive resin / co-Ny / EVOH2 / adhesive resin / LL,
Each layer thickness (μm): 8/4/8/4/4/22,

(Example 9: Total layer thickness: 30 μm)
Heat-resistant polyester 3 / adhesive resin / EVOH1 / co-Ny / adhesive resin / EVA / EP,
Each layer thickness (μm): 4/3/3/5/3/9/3,

(Comparative Example 1: Total layer thickness: 70 μm)
PETG / adhesive resin / 6Ny / EVOH1 / adhesive resin / EVA / EP,
Each layer thickness (μm): 10/5/10/5/5/30/5,

(Comparative Example 2: Total layer thickness: 50 μm)
PETG / adhesive resin / co-Ny / EVOH2 / adhesive resin / LL,
Each layer thickness: 8/4/8/4/4/22,

(Comparative Example 3: Total layer thickness: 30 μm)
PETG / adhesive resin / EVOH1 / co-Ny / adhesive resin / EVA / EP,
Each layer thickness: 4/3/3/5/3/9/3,

(Comparative Example 4: Total layer thickness: 70 μm)
6Ny / adhesive resin / 6Ny / EVOH1 / adhesive resin / EVA / EP,
Each layer thickness: 10/5/10/5/5/30/5,

(Comparative Example 5: Total layer thickness: 50 μm)
Co-Ny / adhesive resin / co-Ny / EVOH2 / adhesive resin / LL,
Each layer thickness: 8/4/8/4/4/22,

(Comparative Example 6: Total layer thickness: 30 μm)
12Ny / adhesive resin / EVOH1 / co-Ny / adhesive resin / EVA / EP,
Each layer thickness: 4/3/3/5/3/9/3,

(Comparative Example 7: Total layer thickness: 70 μm)
PP / adhesive resin / 6Ny / EVOH1 / adhesive resin / EVA / EP,
Each layer thickness: 10/5/10/5/5/30/5,

(Comparative Example 8: Total layer thickness: 50 μm)
PP / adhesive resin / co-Ny / EVOH2 / adhesive resin / LL
Each layer thickness: 8/4/8/4/4/22,

(Comparative Example 9: Total layer thickness: 30 μm)
PP / adhesive resin / EVOH1 / co-Ny / adhesive resin / EVA / EP,
Each layer thickness: 4/3/3/5/3/9/3,

(Comparative Example 10: Total layer thickness: 70 μm)
APET / adhesive resin / 6Ny / EVOH1 / adhesive resin / EVA / EP,
Each layer thickness: 10/5/10/5/5/30/5,

(Comparative Example 11: Total layer thickness: 50 μm)
APET / adhesive resin / co-Ny / EVOH2 / adhesive resin / LL,
Each layer thickness: 8/4/8/4/4/22,

(Comparative Example 12: Total layer thickness: 30 μm)
APET / adhesive resin / EVOH1 / co-Ny / adhesive resin / EVA / EP,
Each layer thickness: 4/3/3/5/3/9/3,

  The boiled food packaging film produced above was drawn with a deep drawing packaging machine (FV-6300) manufactured by Omori. The size of the deep drawing part was formed into a cylindrical shape having a diameter of 98 mm and a drawing depth of 2 mm. The size of the packed product is 100 mm long and 80 mm wide. Molding heating temperature is 90 ° C. The molding time is 1.0 second. A sliced ham (thickness: about 2 mm) was filled into the processed hole, and a lid (covered with the following configuration of the lid film) was covered to obtain a package by vacuum packaging.

Lid material film: OPP (30 μm) // Transparent deposited PET (12 μm) // LLDPE (40 μm),
OPP: OPU-1 (biaxially stretched by Tosero)
Transparent deposition PET: VM-PET (deposition PET made by Toyo Metallizing Co.)
LLDPE: L-6102 (Toyobo Co., Ltd.)
“A layer // B layer” means that the A layer and the B layer are laminated.

<Moldability>
Measure the thickness of the circumferential part of the cylindrical part of the above-mentioned molded part where the molding depth is the deepest using a Mitsutoyo Digimatic indicator, and calculate the average value of the four points. Evaluation was performed. Can not be molded as usual, or less than 80% of the total layer thickness before molding, "X", can be molded as usual and is 80% of the total layer thickness before molding The above was designated as “◯”.

<Boil resistance>
Ten of the packaging bodies were boiled at 98 ° C. for 30 minutes, and the appearance and state of the packaging bodies were confirmed. When the surface of the packaging body is whitened or one or more of the packaging body surfaces are fused "X", when the packaging surface is whitened or the packaging surface is fused at all Was marked as “◯”.

<Curl deterrence>
The package was boiled at 98 ° C. for 30 minutes, cooled in cold water at 5 ° C. for 1 hour, taken out from the water, and allowed to stand at room temperature for 5 hours to confirm the appearance. When the package was allowed to stand with the lid film side down, it was evaluated whether curling had occurred at the end of the package. The curl height of the most curled portion was measured, and “×” was given for curling 10 mm or more, and “◯” was given for the curled portion.

From Table 1, it turns out that Examples 1-9 which use the food packaging film for boil processing of this invention have favorable moldability, boil resistance, and curl suppression property.
On the other hand, since Comparative Examples 1-3 used PETG for the outermost layer and Comparative Examples 10-12 used APET for the outermost layer, the surfaces of the package were fused during boil sterilization.
In addition, Comparative Examples 4 to 6 had poor moldability. Furthermore, in Comparative Examples 4 and 5, the outermost nylon absorbs moisture and contracts when boiled, causing curling and deteriorating the appearance.
Moreover, all of Comparative Examples 7 to 9 had poor moldability.

  The food packaging film for boil treatment of the present invention has a heat resistant polyester resin in the outermost layer, so it has excellent curl deterrence, deep drawability and boil resistance, and is formed of sliced ham, sliced bacon, etc. It is extremely useful as a food packaging material for boil processing of shallow contents.

Claims (6)

A food packaging film for boil treatment comprising at least three layers of an outermost layer, an intermediate layer, and an innermost layer, wherein the resin component constituting the outermost layer has the following characteristics a) and b) A food packaging film for boil treatment having a total thickness of 10 μm or more and 80 μm or less, comprising a heat-resistant polyester resin having a transition point (Tg) of 90 ° C. or more as a main component.
a) In accordance with JIS-K7121, a crystal scanning calorie ΔHm at the time of temperature increase at a temperature increase rate of 10 ° C./min with a differential scanning calorimeter is 20 J / g or less,
b) It consists of two or more types of diol components, and at least one type of diol component has a cyclic structure that does not contain a double bond.   The food packaging film for boil treatment according to claim 1, wherein the thickness of the outermost layer is 10% or more and 60% or less of the total thickness.   The food packaging film for boil treatment according to claim 1 or 2, wherein the intermediate layer is a polyamide resin layer or a multilayer comprising a polyamide resin layer and an ethylene-vinyl acetate copolymer saponified resin layer.   The food packaging film for boil processing in any one of Claims 1-3 whose said innermost layer is a heat seal resin layer.   The bottom material for deep-drawing packaging bodies formed by the food packaging film for boil processing according to any one of claims 1 to 4.   A deep drawn package using the bottom material for a deep drawn package according to claim 5.