JPH022592Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a laminated packaging material that satisfies the functions required of a packaging material, that is, printing suitability, mechanical suitability, heat seal suitability, and protection functions, while reducing the total thickness of the packaging material. BACKGROUND ART Conventionally, so-called polycello, which is made by extrusion laminating polyethylene on cellophane, has been known as a laminated packaging material that satisfies the above-mentioned functions that a packaging material should have. This is a packaging material that maximizes its functionality by taking advantage of cellophane's printability and mechanical suitability, and by combining polyethylene's excellent heat sealability and cellophane's heat resistance. It was excellent. However, in recent years, the functions required of packaging materials have become increasingly diverse, and in addition, films,
Various materials such as resins and various lamination techniques such as dry lamination have been developed, and a large number of laminated packaging materials have been put into practical use by combining materials, number of laminated layers, lamination techniques, etc. However, these packaging materials combine a base layer with excellent printability and mechanical suitability and a sealing layer with excellent heat-sealability to provide the required functionality. The required functions have been provided based on Polycello's technical philosophy, such as providing gas barrier properties by providing a gas barrier layer between the heat seal layer and the heat seal layer. Recently, there has been a desire to conserve resources and energy, and in the field of laminated packaging materials, there has been a particular demand for thinner films and a reduction in the number of laminated layers. The inventors of the present invention have discovered a laminated packaging material that is a thin film with excellent printability, mechanical suitability, heat sealability, and excellent protective function. That is, a base layer (hereinafter referred to as base layer) made of a biaxially stretched polyester or nylon film or cellophane, and a heat seal layer (hereinafter referred to as heat seal layer) made of a biaxially stretched polypropylene inline composite film having heat sealability. ) are laminated using an adhesive and have a thickness ratio within the range shown by the formula below, and in the laminated packaging material, printing is performed on the inner surface of the base layer. The present invention is a laminated packaging material in which at least a uniaxially stretched polyolefin layer of the heat-sealing layer is disposed on the outer surface of the laminated packaging material. DESCRIPTION OF THE PREFERRED EMBODIMENTS The laminated packaging material of the present invention will be described in detail below based on embodiments shown in the drawings. The base layer A is a film having excellent strength and heat resistance, such as a polyester biaxially stretched film, a nylon biaxially stretched film, or cellophane. Here, the polyester biaxially stretched film is
It is a biaxially stretched film formed from polyethylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalate, etc., or a copolymer or polymer mixture containing these as main components. It is a biaxially stretched film formed from nylon 6.6, nylon 6.10, polyxylylene adipamide, etc., or a copolymer or polymer mixture containing these as main components. Cellophane is ordinary cellophane or moisture-proof cellophane. The heat sealing layer C is formed by laminating a low melting point polyolefin film layer C ₂ on at least one side of a high melting point polypropylene film layer C ₁ and then stretching the film layer C ₂ in at least one direction. After melt lamination extrusion with layer C ₂ and biaxial stretching, film layer C ₁
Film layer _{C 2} is melt-extruded onto the unstretched film layer of C ₁ and then biaxially stretched. ₁
It can be obtained by stretching in a direction perpendicular to the stretching direction of a uniaxially stretched film layer. Thus, the high melting point polypropylene film must be biaxially stretched, and the low melting point polyolefin film must be at least uniaxially stretched. In the laminated packaging material of the present invention, the high melting point polypropylene film layer C ₁ and the low melting point polyolefin film layer C ₂ are arranged such that at least the low melting point polyolefin film layer C ₂ , which is largely involved in heat sealability, is arranged on the outer surface. It is necessary to locate it. For example, as shown in FIG. 2, a biaxially stretched polypropylene layer 2 may be disposed on the base layer 1 side via an adhesive layer 3, and at least a uniaxially stretched polyolefin layer 4 may be disposed on the outer surface. Further, as shown in FIG. 3, at least uniaxially stretched polyolefin layers 4, 4 may be disposed above and below the biaxially stretched polypropylene layer 2 via the dressing layer 3 on the base layer 1 side, or , as shown in FIG. 4, a layer 5 with excellent adhesiveness stretched at least uniaxially is disposed on the base layer 1 side via an adhesive layer 3, and a biaxially stretched polypropylene layer 2 is stretched at least uniaxially. The polyolefin layer 4 may be arranged in this order, or, as shown in FIG. A layer 2, an at least uniaxially stretched layer 5 with excellent adhesive properties, and an at least uniaxially stretched polyolefin layer 5 may be provided. It is preferable to arrange at least a uniaxially stretched layer with excellent adhesive properties on the adhesive layer side, since this improves adhesion with the adhesive used in lamination with the base layer. Further, the layer may be an in-line coating layer. For the layer with excellent adhesiveness, any resin that improves adhesiveness can be used. Examples include ethylene-vinyl acetate copolymer, Surlyn (manufactured by DuPont), and Admar (manufactured by Mitsui Petrochemicals). The high melting point polypropylene film of the heat seal layer is a biaxially stretched layer of isotactic polypropylene, and usually has a thickness in the range of 10 to 100 microns. It goes without saying that isotactic polypropylene that has been subjected to various modifications may be used as long as the physical properties of the film are not significantly impaired. For example, instead of a polypropylene homopolymer, a copolymer of propylene and a small amount of other olefin may be used, or a small amount of other polymer such as a propylene-ethylene copolymer or a propylene-butene-1 copolymer may be used. Olefin copolymers such as polymers, polyethylene, polybutene-1, etc.) may be mixed. Various additives known to be added to isotactic polypropylene may also be added. In addition, the low melting point polyolefin film of the heat-sealing layer is composed of an olefin-based polymer or copolymer that has heat-sealing properties.
Examples of olefin polymers include polyethylene and polybutene-1, and examples of olefin copolymers include propylene/ethylene copolymer, propylene/butene-1 copolymer, ethylene/butene-1 copolymer, and ethylene.・Propylene butene
1 terpolymer, an ethylene/acrylic acid copolymer, an ionomer made by metallizing an ethylene/acrylic acid copolymer, or a mixture of polyethylene with one or more of the above copolymers. do. The base layer and the heat seal layer are laminated via an adhesive, and appropriate lamination methods include polyethylene extrusion sand lamination, dry lamination, and non-solvent lamination. In addition, in the lamination process, if the heat seal layer is coated with an adhesive layer,
It is easy to obtain laminated packaging materials with good printing dimensional accuracy. The thickness of the laminated packaging material is as follows: a is the thickness of the base layer A, b is the thickness of the adhesive layer B, and c _is the thickness of the high melting point polypropylene film layer _C1 of the heat seal layer.
Similarly, when c ₂ is assumed, the thickness c ₂ of the low melting point polyolefin film layer must be in a range that satisfies a+b+c ₁ /10≦c ₂ ≦a+b+c ₁ . Further, if necessary, a different type of film (for example, an aluminum foil, a polypinylidene chloride layer, an ethylene vinyl acetate saponified layer, a vinylon layer, etc.) may be sandwiched between the base layer and the heat seal layer. Furthermore, it is more practically useful if the inner surface of the base layer, that is, the adhesive layer side, is printed. The laminated packaging material with the above structure uses a polyester or nylon biaxially oriented film or cellophane with excellent strength and heat resistance for the base layer, and a biaxially oriented polypropylene inline composite film for the heat seal layer. Therefore, when forming a sealing layer of the same thickness, the laminated packaging material of the present invention has improved elasticity, transparency, strength, and moisture resistance compared to a conventional polyethylene heat sealing layer, and as a result, the laminated packaging material of the present invention has improved stiffness, transparency, strength, and moisture resistance. When trying to achieve the same functionality as a conventional seal layer, it is possible to maintain strength and protection even if the layer is made thinner than a conventional seal layer, and in addition, the seal layer is stretched. This makes it possible to make the layer even thinner. Furthermore, the laminated packaging material of the present invention has excellent tear-opening properties since the stretched film portion occupies most of the total thickness. In addition, especially when heat sealing is performed at a temperature that melts the high melting point polypropylene film layer of the heat seal layer, the entire biaxially oriented polypropylene inline composite film is involved in the heat sealing, which significantly increases the heat seal strength. It also has the characteristic that it can be made into something. Example 1 A 12μ polyethylene terephthalate biaxially oriented film (PET) was used as the base layer, and a biaxially oriented polypropylene film (OP) was used as the heat seal layer.
(20μ) and a propylene ethylene copolymer uniaxially stretched film (EP) layer (5μ). Using a laminated packaging material with a layer of 1.5μ), a horizontal pillow packaging machine can be used at a speed of 180 pieces/pack.
Packaged the box body in minutes. The relationship between the seal strength of the cut seal portion and the seal bar temperature was as follows.

[Table] At temperatures above 240℃, the OP layer also contributes to heat seal strength. Example 2 A composite film shown in Table 2 below was prepared,
Their properties were compared (adhesive layer thickness 1.5μ). The results are shown in Table 2. The meanings of the symbols in the table are as follows. OPP: Biaxially oriented polypropylene film CPP: Unoriented polypropylene film EP: Uniaxially oriented ethylene/propylene copolymer film HP: Biaxially oriented polypropylene inline composite film with heat sealability. When using OPP20μ and EP50μ laminated films for lamination, the EP layer becomes the outer layer. OES: Biaxially oriented polyester film

[Table] As shown in the table above, the packaging material of the present invention is excellent in both packaging speed and heat-sealing strength despite its thin thickness. On the other hand, the sheet of Comparative Example (2-1) is not stiff and the packaging speed cannot be increased. (2
-2) The packaging speed cannot be increased due to the lack of heat resistance of OPP. (2-3) has a thin heat seal layer,
Heat sealing strength is weak and practicality is poor. Example 3 A laminated film having the structure shown in FIG. 1 was produced by changing the thicknesses of C ₁ and C ₂ respectively. A, B, C ₁ C ₂ in the same figure are configured as follows, and A, B
The thickness of each was kept constant. A: Biaxially oriented polyester film (OES) B: Adhesive layer C ₁ : Biaxially oriented polypropylene film (OPP) C ₂ : Uniaxially oriented ethylene-propylene copolymer film (EP) The results are shown in Table 3.

[Table] As can be seen from Table 3, those that satisfied the conditions a+b+c ₁ /10≦c ₂ ≦a+b+c ₁ gave good results in terms of both seal strength and stiffness, but those that did not satisfy the condition, especially Those that do not satisfy a+b+c ₁ /10≦c ₂ have a reduced sealing strength, and those that do not satisfy c ₂ ≦a+b+c ₁ +c ₃ have a reduced stiffness.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing an example of the laminated packaging material of the present invention, and FIGS. 2 to 5 are cross-sectional views showing examples. A...Base layer, B...Adhesive layer, C...Heat seal layer, _C1 ...High melting point polypropylene film layer, C2...Low melting point polyolefin film layer, ₁ ...Base layer, 2... ... Biaxially stretched polypropylene layer, 3... Adhesive layer, 4... Polyolefin layer stretched at least uniaxially, 5... Layer with excellent adhesiveness stretched at least uniaxially.

Claims (1)

[Claims for Utility Model Registration] (1) A base layer made of a polyester or nylon biaxially oriented film or cellophane and a heat sealing layer made of a biaxially oriented polypropylene inline composite film having heat sealing properties are coated with an adhesive. The thickness of the high melting point polypropylene film layer C ₁ of the biaxially oriented polypropylene inline composite film is c ₁ , the thickness of the low melting point polyolefin film layer C ₂ is c ₂ , and the base layer A When the thickness of the adhesive layer B is a, and the thickness of the adhesive layer B is b, the following relational expression holds between the thicknesses of each layer, and the above-mentioned low melting point polyolefin film layer _C2 is disposed on the outer surface. Characteristic laminated packaging material. a+b+c ₁ /10≦c ₂ ≦a+b+c ₁ (2) The laminated packaging material according to claim 1 of the utility model registration, in which printing is performed on the inner surface of the base layer.