JPS6036457Y2 - Laminated film for packaging - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a flexible laminated film for packaging that has excellent gas barrier properties, moisture resistance, heat sealability, etc., and also has excellent deep drawability and slitting properties.

Molded products made by deep drawing of plastic materials with excellent heat sealability and deep drawing formability are widely used as bottom materials for packaging when foods such as sliced ham and grilled pork are displayed in stores.

By the way, this type of packaging material not only has the gas barrier properties, moisture resistance, transparency, etc. required for general food packaging materials, but also has deep drawing properties required for packaging bottom materials. The product must have heat-sealing properties that allow it to be sealed with a separate lid material by heat welding, and it must have excellent deep drawability (i.e., a deep-drawn product formed as a bottom material has a A wide range of properties are required, such as no wrinkles due to stretching strain) and excellent gloss on the surface of the molded product, and packaging films that satisfy all of these properties. In particular, it has been difficult to obtain packaging films that also have flexibility.

By adopting the structure described in the claims for utility model registration, this invention not only has good gas barrier properties, moisture resistance, transparency, heat sealability, etc., but also good deep drawability, slitting properties, etc. The present invention provides a flexible laminated film for packaging that can be formed into a deep-drawn product having excellent surface gloss.

The structure of the packaging laminated film of the present invention will be explained below based on illustrated embodiments.

In the embodiment shown in FIG. 1, a laminated packaging film 1 of the present invention is shown.
is an unstretched saturated polyester layer 2 with a thickness of 20 to 100μ
and the thermally weldable coating layer 3 is made of ethylene-acetic acid having a thickness of 10 to 30μ, an ethylene content of 20 to 40 mol%, and a degree of saponification (degree of saponification relative to vinyl acetate in the copolymer) of 95 mol% or more. The unstretched saturated polyester layer 2 of the three-layer film 5, which is a multilayer film, is directly heat-welded to the core layer 4 through the core layer 4 made of a saponified vinyl copolymer. The non-stretched polypropylene layer 6 is directly thermally welded and laminated.

In the third illustrated embodiment, the packaging laminated film 7 of the present invention includes an unstretched saturated polyester layer 8 with a thickness of 20 to 100 μm, an ethylene content of 20 to 40 mol%, a saponification degree of 95 mol%, and a thickness of 10 to 30 μm. A coating layer 11 having thermal fusibility is further adhered to the core layer 9 side of the bonded laminate 10, in which the core layer 9 made of the above saponified ethylene-vinyl acetate copolymer is bonded to the core layer 9 by an adhesive layer m1. A multilayer film 12 is formed by laminating the agent layer m2, and the non-stretched saturated polyester layer 8 of this multilayer film 12
It consists of a structure in which an unstretched polypropylene layer 13 with a thickness of 20 to 60 μm is bonded to the side by an adhesive layer m3.

The core layer 4 made of saponified vinyl acetate copolymer constituting the packaging laminated film 1 of the present invention, together with the unstretched saturated polyester layer 2, provides the packaging laminated film 1 with excellent gas barrier properties. However, if the ethylene content of the saponified ethylene-vinyl acetate copolymer constituting the core layer 4 exceeds 40 mol%, it becomes impossible to impart the desired gas barrier properties to the core layer 4. It's inappropriate.

Furthermore, if the ethylene content is less than 20 mol%, the saponified ethylene-vinyl acetate copolymer itself has poor extrusion moldability, making it impossible to obtain a uniform product. The constituting saponified ethylene-vinyl acetate copolymer must have an ethylene content in the range of 20 to 40 mol%.

Furthermore, if the degree of saponification in the saponified ethylene-vinyl acetate copolymer is less than 95 mol%, the core layer 4 will not have a sufficient gas barrier, as in the case where the ethylene content in the saponified product exceeds 40 mol%. - properties cannot be imparted, so the degree of saponification must be 95 mol% or more.

Furthermore, if the thickness of the core layer 4 is less than 10 μm, the gas barrier effect will not be sufficient, and if it exceeds 30 μm, the thickness of the entire laminated film 1 will become thicker and the deep drawability will deteriorate. In addition, the flexibility of the laminated film 1 itself is reduced, so it is necessary that the core layer 4 has a thickness within the range of 10 to 30 μm.

The unstretched saturated polyester layer 2 laminated on the core layer 4 provides the laminated packaging film 1 with excellent deep drawability at low temperatures, and also provides the core layer 4 with a gas barrier under high humidity. It also has the effect of suppressing sexual decline.

This unstretched saturated polyester layer 2 has a thickness of 25 μm.
If the thickness is less than 100μ, the effect of the unstretched saturated polyester layer 2 will not be sufficient, and if it exceeds 100μ, the overall thickness of the laminated film 1 will become too thick, as in the case of the core layer 4, and the depth of the laminated film 1 will increase. Since this may cause problems such as poor drawability and reduced flexibility,
It is necessary that the thickness be within the range of 100μ.

This unstretched saturated polyester layer 2 also has the function of providing excellent gloss to the laminated packaging film 1;
This excellent gloss is also imparted to the deep-drawn product formed from this packaging laminated film 1, and the laminated film 1 retains the excellent gloss that the laminated film 1 itself has. It is also one of the characteristics of the laminated film of the present invention that a deep-drawn molded product having the following properties can be obtained.

In the packaging laminated film 1 of the present invention, a heat-fusible covering layer 3 that is laminated on the core layer 4 on the opposite side of the unstretched saturated polyester layer 2 is heat-sealed to the packaging laminated film 1. For example, the molded product is fixed to a deep-drawn molded product as shown in FIG. 2, which is formed using the packaging laminated film 1 as a molding material, by heat sealing with a separate lid material. It has such properties.

Therefore, the coating layer 3 having heat-weldability is made of a resin that exhibits heat-sealing properties, such as polyethylene, ethylene-vinyl acetate copolymer, ionomer resin, etc., and has a thickness of about 40 to 100 μm. However, by forming the coating layer 3 with a resin that has both heat sealability and water resistance, the core layer 4 made of a saponified ethylene-vinyl acetate copolymer can be It is also preferable to have the effect of suppressing the deterioration of gas barrier properties under high humidity.

The laminated film for packaging 1 has a three-layer structure film 5 which is a multilayer structure film, that is, an unstretched saturated polyester layer 2 having a thickness of 25 to 100 μm and a coating layer 3 having thermal fusibility, which has a thickness of 10 to 30 μm. Ethylene content of 20-40
Three layers of a multilayer film laminated with a core layer 4 made of a saponified ethylene-vinyl acetate copolymer having a saponification degree (saponification degree relative to vinyl acetate in the copolymer) of 95 mol% or more by mol%. An unstretched polypropylene layer 6 having a thickness of 20 to 60 μm is further laminated on the unstretched saturated polyester layer 2 side of the constituent film 5.

This unstretched polypropylene layer 6 provides the laminated packaging film 1 with good slitter properties without impairing the high glossiness of the unstretched saturated polyester layer 2 in the three-layer film 5, which is the multilayer film. (
For example, when individually cutting a plurality of molded products formed from a single sheet-shaped packaging laminated film 1, the slitting performance is extremely good. It is.

If the thickness of the unstretched polypropylene layer 6 is less than 20 μm, its effect will not be sufficient, and if the thickness exceeds 60 μm, the overall thickness of the laminated film 1 will become too thick, and the excellent deep drawability of the laminated film 1 will deteriorate. It is necessary to have a thickness within the range of 20 to 60 μm since the thickness may be lowered or the flexibility may be lowered.

The laminated film for packaging of the present invention has the above-mentioned structure, for example (i) a heat-fusible coating layer, such as polyethylene resin, ethylene content of 20 to 40 mol%, saponification degree of 95 mol% or more; A co-extrusion method in which four types of thermoplastic synthetic resins consisting of a saponified ethylene-vinyl acetate copolymer, a saturated polyester resin, and a polypropylene resin are co-extruded; (iii) The so-called extrusion lamination method, in which molten thermoplastic synthetic resin extruded from a T-die is sandwiched and laminated together; It can be manufactured using a manufacturing method such as a so-called dry lamination method.

The laminated film for packaging of the present invention has the structure as described above, and has excellent gas barrier properties regardless of humidity, as well as excellent deep drawability and heat sealability at low temperatures. It has a good balance of physical properties required for packaging materials, such as transparency, moisture resistance, and flexibility, and exhibits excellent functions and effects as a packaging material.

Furthermore, the laminated packaging film of the present invention has good deep drawing formability at low temperatures, and can be used as a bottom material for packaging foods such as sliced ham and grilled pork by deep drawing at a forming temperature of about 120 to 130°C. A deep-drawn product that satisfies all the physical properties required for deep-drawing, that is, there are no streaks due to uneven stretching during deep drawing, and there is no possibility that some corners of the recess may become extremely thin due to local stretching. radial wrinkles do not occur on the bottom surface of the recess due to stretching even when the recess is filled with contents, and furthermore, the product retains the excellent surface gloss characteristic of the unstretched polyester layer. Since it can be molded and has excellent slitting properties, it has extremely excellent functions and effects as a molding material for bottom materials for food packaging.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a model showing one embodiment of the laminated packaging film of the present invention, FIG. 2 is a cross-sectional view of a model of a deep-drawn product using the laminated packaging film of the present invention as a molding material, and FIG. The figure is a schematic cross-sectional view showing another embodiment of the packaging laminated film of the present invention. DESCRIPTION OF SYMBOLS 1... Packaging laminated film, 2... Unstretched saturated polyester layer, 3... Covering layer, 4...
. . . Central core layer, 5 . . . Three-layer film which is a multilayer film, 6 .

Claims (1)

[Scope of utility model registration request] An unstretched saturated polyester layer with a thickness of 25 to 100μ and a heat-fusible coating layer have a thickness of 10 to 30μ, an ethylene content of 20 to 40 mol%, a saponification degree (saponification degree with respect to vinyl acetate in the copolymer) ) An unstretched polypropylene layer with a thickness of 20 to 60 μm on the unstretched saturated polyester layer side of the multilayer film laminated via a core layer made of saponified ethylene-vinyl acetate copolymer of 95 mol% or more. A laminated film for packaging characterized by being laminated with.