JP2016050025A - Sealant film for lid material of cup-shaped container for ice candy, and lid material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance heat sealability without impairing openability of a lid material of a cup-shaped container for an ice candy like a newly developed container formed of A-PET.SOLUTION: A sealant film 6 for a lid material of a cup-shaped container for an ice candy is formed by bonding a seal layer 13 to a base material layer 11. The sealant layer 13 is formed by blending any resin of polyester and polyolefin with low Tg polyester having a lower glass transition temperature than that of the resin and has a glass transition temperature of -30°C or lower so that the low Tg polyester becomes 50 mass% or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sealant film for a lid material of a cup-shaped container used as a packaging container for ice confectionery such as ice cream and a lid material having the sealant film.

As a cup-shaped container used as a packaging container for ice confectionery such as ice cream and confectionery, a container body is known in which a lid is heat sealed. This type of cup-shaped container is required to be able to reliably heat-seal the lid and to be easily opened.
Conventionally, for example, those disclosed in Patent Literatures 1 to 3 have been disclosed as lid materials for cup-shaped containers or heat-sealing films thereof with improved heat sealability and openability.

  Patent Document 1 discloses a composition obtained by melt-mixing 100 parts by weight of a thermoplastic polyester having a melting point of 80 to 200 ° C. and 1 to 100 parts by weight of a polyolefin resin with respect to a container made of polycarbonate or polyester (particularly polyethylene terephthalate). A film-like laminate in which a thin layer is laminated on the surface of a film-like material is disclosed, and is described as being excellent in heat-sealability and easy-open property.

  Patent Document 2 discloses a polymer film in which a coating layer containing a copolyester obtained by polymerizing an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or the like is formed on a support layer of a polymer material. In this case, the copolyester has a glass transition temperature of 10 ° C. or less, more preferably in the range of −10 ° C. to −2 ° C., and if the glass transition temperature is outside this range, the final Describes that there is a possibility of a decrease in peelability that causes tearing without clean separation.

  Patent Document 3 mainly describes a crystalline polyester having a glass transition temperature of 0 ° C. or lower and a melting point of 120 to 200 ° C. with respect to a container body formed of crystallized polyethylene terephthalate (referred to as C-PET). The sealing material which consists of the polyester resin composition as a component is indicated, and it is described that it is excellent in heat sealability and openability (easy peel property) at a low temperature.

JP-A 63-17048 Japanese National Patent Publication No. 10-510771 JP 11-349708 A

  By the way, a polyester resin is mainly used for the container body of this type of cup-shaped container. In this case, crystallized polyethylene terephthalate (C-PET) described in Patent Document 3 has been used as a material for ice confectionery cup-shaped containers such as ice cream, but in recent years, amorphous polyethylene terephthalate (A-PET) has been used. Have been developed.

This A-PET has been widely used as a container material for contents, beverages, etc. at room temperature or refrigerated storage, and since it is more transparent than C-PET, it is used for frozen desserts that are stored frozen. The application is expected to expand its use.
However, this newly developed A-PET cup-shaped container lid material was bonded by hot melt in the case of conventional room temperature or refrigerated storage, but is not suitable for frozen storage and the sealing performance is impaired. There is a problem of being.

  The present invention has been made in view of such circumstances, and, like a container made of newly developed A-PET, has a heat-sealing property without impairing the opening of the lid material of the cup-shaped container for ice confectionery. The purpose is to improve.

  The sealant film for a lid material of a cup container for ice confectionery according to the present invention is formed by adhering a sealing layer to a base material layer, and the sealing layer is made of either polyester or polyolefin resin, and has a glass transition more than this resin. A low Tg polyester having a low temperature and a glass transition temperature of −30 ° C. or less is blended so that the low Tg polyester is 50% by mass or more.

  By blending low Tg polyester as the main component of the seal layer, the flexibility of the resin is maintained even in a frozen state, and an appropriate seal strength can be obtained. When the glass transition temperature of this low Tg polyester is higher than -30 ° C, the resin becomes hard in a frozen state and peels off from the container body, or conversely, the sealing strength becomes too high, and the lid material is peeled off. There is a defect that breaks. Moreover, even if the glass transition temperature is -30 ° C. or lower, if the blending ratio of this low Tg polyester is less than 50% by mass, it becomes similarly hard in the frozen state and peels off from the container body, and the seal strength is high. There is a problem that the cover material is torn when peeling off because it is too high.

In the sealant film for a lid material of the present invention, the low Tg polyester may be blended so as to be 80% by mass or less.
Even if the blending ratio of the low Tg polyester is high, the sealing property and the unsealing property are not impaired. However, if it is too high, the resin becomes soft and the molding becomes difficult, for example, warpage occurs during film molding. For this reason, the blending ratio of the low Tg polyester is preferably 80% by mass or less.

Moreover, the lid material of the cup-shaped container for ice confectionery of the present invention is characterized in that the sealant film is laminated on a base film.
In addition, the thickness of the sealant film for a lid material of the present invention is preferably 50 μm or less, and the thickness of the entire lid material is preferably 250 μm or less.

  According to the present invention, the flexibility of the resin is maintained even in the frozen state, the sealing strength can be made moderate, and there is no problem such as tearing of the lid material when peeled off, and the sealing property and opening in the frozen state It is possible to balance the sex.

It is sectional drawing which shows one Embodiment of the cover material of the cup-shaped container for ice confectionery of this invention. It is a front view of the cup-shaped container for ice confectionery which heat-sealed the lid | cover material shown in FIG.

Embodiments of the present invention will be described below with reference to the drawings.
The cup-shaped container according to the present invention is composed of a cup-shaped container main body 1 having an open top and a lid member 2 that closes the upper end opening of the container main body. A flange portion 3 is integrally formed at the upper end of the container body 1, and the lid member 2 is heat-sealed on the upper surface of the flange portion 3.
The lid member 2 has a configuration in which a base film 5 and a sealant film 6 are laminated. The base film 5 is disposed on the outer surface side of the lid member 2 and can be applied as a base film for a lid member of a general cup-shaped container. For example, the resin layer 7 , 8, a composite film obtained by laminating paper 9 such as fine paper, coated paper, kraft paper or the like is used. Specifically, it is preferable that paper 9 is laminated between resin layers 7 and 8 made of polyester (particularly biaxially stretched polyethylene terephthalate). Of course, the resin layers on both sides may be made of different resins, a single layer film such as a stretched polyester resin, a laminate film with a metal foil such as aluminum, and the like are also applicable.

  The sealant film 6 is disposed on the inner surface side of the lid member 2 and includes a base material layer 11 made of low-density polyethylene, high-density polyethylene, polypropylene, or the like, and an adhesive layer made of acrylic resin, urethane resin, olefin resin, or the like. 3 and a sealing layer 13 made of polyester resin or the like are laminated in this order. The base material layer 11, the adhesive layer 12, and the seal layer 13 are formed by, for example, laminating while extruding films of each layer by hot three-layer coextrusion.

  The resin constituting the sealing layer 13 is formed by mixing any one of ordinary polyester and polyolefin (polyethylene, polypropylene, etc.) resin with a low Tg polyester having a glass transition temperature lower than that of this resin. In this case, it mix | blends so that low Tg polyester may be 50 mass% or more. The polyester resin is preferably polyethylene terephthalate (PET), most preferably a combination of low Tg polyethylene terephthalate and ordinary polyethylene terephthalate.

  The glass transition temperature of ordinary polyester resin is 69 ° C. to 80 ° C., whereas the glass transition temperature of low Tg polyester is that the freezing temperature of the ice confectionery in the contents is −20 ° C. to −30 ° C. It shall be -30 degrees C or less. When the glass transition temperature of this low Tg polyester is higher than -30 ° C, the resin becomes hard in a frozen state and peels off from the container body, or conversely, the sealing strength becomes too high, and the lid material is peeled off. There is a defect that breaks. If the glass transition temperature is too low, the resin becomes soft and warping occurs during film molding, which prevents molding from being mixed. Therefore, the glass transition temperature is preferably −90 ° C. or higher, and preferably about −70 ° C.

  There are various polyester resins having a low glass transition temperature (Tg) of −30 ° C. or lower. For example, a polyvalent carboxylic acid selected from terephthalic acid, isophthalic acid, sebacic acid, and the like, a polyalcohol ( Diol) is blended and subjected to ester reaction at a temperature of 170 ° C. to 220 ° C. for a predetermined time. The glass transition temperature (Tg) is adjusted by the reaction progress (polycondensation degree) at this time. As a commercially available product, for example, GM-913 (Tg = −70 ° C.) manufactured by Toyobo Co., Ltd. can be used.

  In addition, when the blending ratio of the low Tg polyester is less than 50% by mass, it becomes hard in the frozen state and peels off from the container body, or the sealing strength becomes too high, and the lid material is broken when peeled off. is there. On the other hand, if the blending ratio of the low Tg polyester becomes too high, the resin becomes soft and the molding becomes difficult, for example, warpage occurs during film molding. For this reason, the blending ratio of the low Tg polyester is preferably 80% by mass or less.

The lid 2 made of such a material has an overall thickness of 40 μm or more and 250 μm or less, of which the sealant film 6 has a thickness of 12 μm or more and 50 μm or less. The sealant film 6 further has a base material layer 11 of 5 μm to 20 μm, an adhesive layer 12 of 5 μm to 20 μm, and a seal layer 13 of 2 μm to 10 μm.
For example, the base film 5 of the lid material 2 is a laminated film of resin layer (thickness 12 μm) / paper (84 g / m ² ) / resin layer (thickness 12 μm), while the sealant film 6 is a base layer (thickness). 12.5 μm) / adhesive layer (thickness 12.5 μm) / seal layer (thickness 5 μm).
Since this lid material 2 was formed by mixing a normal resin and a low Tg polyester resin having a glass transition temperature of −30 ° C. or lower to form the seal layer 13 of the sealant film 6, As a container lid, both sealing properties and unsealing properties can be achieved.

A sealant film is blended with a base layer (thickness 12.5 μm) made of low-density polyethylene, an adhesive layer (thickness 12.5 μm) made of an acrylic resin, and resin 1 and resin 2 shown in Table 1 in the indicated ratio. A seal layer (thickness: 5 μm) having a three-layer structure was formed by extrusion molding, and the sealant film was laminated on a base film to form a lid.
Resin 1 PET-G is an amorphous polyester resin (glycol-modified polyester). A and B are indicated by the difference in grade. As the low Tg polyester resin of the resin 2, a resin having a glass transition temperature of −70 ° C. (GM-913 manufactured by Toyobo Co., Ltd.) was used.
The base film was a polyethylene terephthalate layer (thickness 12 μm) / paper (84 g / m ² ) / polyethylene terephthalate layer (thickness 12 μm).
This lid material was heat-sealed in a cup-shaped container made of A-PET, and the opening strength was measured.
The heat seal condition was 180 ° C. × 0.2 MPa × 2 seconds.
The unsealing strength was measured by an autograph at 200 mm / min. The unsealing strength was measured for both a cup-shaped container stored at 25 ° C. (normal temperature) for 24 hours and a container stored at −20 ° C. for 24 hours. Ten samples were measured at each temperature, and the average value was recorded.
These results are shown in Table 1. In Table 1, the remarks column records whether or not the lid material was torn when the opening strength was measured at −20 ° C.

As is clear from the results of Table 1, the sealing layer containing low Tg polyester at a ratio of 50% by mass or more has good opening strength at both 25 ° C. and −20 ° C. It can be seen that the lid material is sometimes not broken and is suitable as a lid material for a cup container for ice confectionery. When the blending ratio of the low Tg polyester resin was low (40% by mass or less), the lid material was torn during opening at −20 ° C. In addition, No. 1 in which the seal layer was composed of only ordinary PET-G (A) not containing low Tg polyester. In the case of 1, peeling occurred from the seal portion at −20 ° C.
However, No. No. with a low Tg polyester resin blending ratio of 85% by mass. No. 8 was able to be molded as a lid material, but the opening strength and the tearing of the lid material were good, but some of them were poorly molded. Although it does not become defective as a product, it can be said that the blending ratio of the low Tg polyester is preferably 80% by mass or less in terms of moldability.

  In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 Cup-shaped container 2 Cover material 3 Flange part 5 Base film 6 Sealant film 7, 8 Resin layer 9 Paper 11 Base material layer 12 Adhesive layer 13 Sealing layer

Claims (3)

  A sealing layer is bonded to a base material layer, and the sealing layer includes a polyester or polyolefin resin, and a low Tg polyester having a glass transition temperature lower than or equal to −30 ° C. than the resin. A sealant film for a lid for a cup-shaped container for ice confectionery, wherein the low Tg polyester is blended so that the amount thereof is 50% by mass or more.   The sealant film for a lid material of a cup container for ice confectionery according to claim 1, wherein the low Tg polyester is blended so as to be 80% by mass or less.   A lid material for a cup container for ice confectionery, wherein the sealant film for a lid material for a cup container for ice confectionery according to claim 1 or 2 is laminated on a base film.

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