JPH023871Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention is a laminated packaging material that satisfies the functions required of a packaging material, that is, printability, mechanical suitability, heat seal suitability, protective function, reduces the total thickness of the packaging material, and has UV blocking properties. It is related to. BACKGROUND ART Conventionally, as a laminated packaging material that satisfies the above-mentioned functions that a packaging material should have, a material made by extrusion laminating polyethylene on cellophane has been known. 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, various materials such as films and resins and various lamination techniques such as dry lamination have been developed. A large number of laminated packaging materials are put into practical use by combining the following. However, these packaging materials provide the required functionality by combining a base layer with excellent printability and mechanical suitability and a sealing layer with excellent heat sealability. 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. Furthermore, from the viewpoint of food hygiene, there is a strong demand for prevention of deterioration of packaging materials due to food oxidation. The present inventor has discovered a laminated packaging material that is a thin film that has excellent printability, mechanical suitability, and heat sealability, as well as excellent UV blocking properties and excellent protective functions. 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 "base layer") made of an opaque biaxially stretched polyolefin inline composite film having heat sealability.
This is a laminated packaging material in which the heat-sealing layer) is laminated using an adhesive and has a thickness ratio within the range shown by the formula below, and in the laminated packaging material, the inner surface of the base layer The present invention is a laminated packaging material in which printing is performed on the laminate packaging material, and a polyolefin layer stretched in at least one axis of the heat-sealing layer is disposed on the outer surface of the laminated packaging material. Hereinafter, the opaque laminated packaging material of the present invention will be described in detail based on embodiments shown in the drawings. 1st
In the figure, the film constituting the base layer A is a film with 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. Nylon 6,6, nylon 6,1
0. It is a biaxially stretched film formed from 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 polyolefin film layer C ₁ and then stretching it in at least one direction. The layer or the low melting point polyolefin film layer is opaque. For example, by melt laminating and extruding film layer C ₁ and film layer C ₂ and then biaxially stretching,
The film layer C ₂ is melt-extruded onto the unstretched film layer of the film layer C ₁ and then biaxially stretched, whereby the film layer C ₂ is melt-extruded onto the uniaxially stretched film layer of the film layer C ₁ , and then ,
It can be obtained by stretching the film layer _C1 in a direction perpendicular to the stretching direction of the uniaxially stretched film layer. As described above, it is necessary that the high melting point polyolefin film is biaxially stretched, and the low melting point polyolefin film is at least uniaxially stretched. In the opaque laminated packaging material of the present invention, at least the high melting point polyolefin film layer C ₁ and the low melting point polyolefin film layer C ₂ are disposed on the outer surface, and the low melting point polyolefin film layer C ₂ , which largely contributes to heat sealability, is arranged on the outer surface. In addition, it is preferable to arrange an opaque biaxially oriented polyolefin film as the high melting point polyolefin film layer.
The low melting point polyolefin film layer may be an opaque layer. For example, as shown in FIG. 2, an opaque biaxially stretched polyolefin layer 2 may be disposed on the base layer 1 side via an adhesive layer 3, and an at least uniaxially stretched polyolefin layer 4 may be disposed on the outer surface. Also,
As shown in FIG. 3, an adhesive layer 3 is placed on the base layer 1 side.
At least uniaxially stretched polyolefin layers 4, 4 may be disposed above and below the opaque biaxially stretched polyolefin layer 2, and as shown in FIG. 4, an adhesive layer may be placed on the base layer 1 side. A layer 5 with excellent adhesive properties stretched at least uniaxially through the polyolefin layer 3 may be disposed in this order, followed by an opaque biaxially stretched polyolefin layer 2 and a polyolefin layer 4 stretched at least uniaxially. As shown in the figure, a layer 5 with excellent adhesiveness that is stretched at least uniaxially is disposed on the side of the base layer 1, followed by an opaque biaxially stretched polyolefin layer 2, and a layer 5 that has excellent adhesiveness that is stretched at least uniaxially. 5. At least a uniaxially stretched polyolefin layer 4 may be provided. In the figure,
6 is printing ink. Here, in the explanation of FIGS. 2 to 5 above,
The opaque biaxially oriented polyolefin layer 2 is shown as a single layer, but will be described in detail as follows. (1) When all the layers of the film are opaque film layer 21 (Fig. 6) (2) When laminating a transparent film layer and an opaque film layer, the opaque film layer 21 is on the base layer side.
Allocate. (Fig. 7) (3) When laminating a transparent film layer and an opaque film layer, the transparent film layer 22 is placed on the base layer side. (Figure 8) (4) Transparent film layer 22, opaque film layer 2
1. The transparent film layer 22 is laminated in this order. (Figure 9) (5) Opaque film layer 21, transparent film layer 2
2. Laminate the opaque film layer 21 in this order.
(Fig. 10) Opaque films can be obtained by adding inorganic substances such as calcium carbonate or pigments, but the degree of opacity can be set according to requirements. 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 opaque high melting point polyolefin film of the heat seal layer is mainly a biaxially stretched layer of isotactic polypropylene, and usually has a thickness of 10-
A range of 100 microns is used. Of course, 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 with small amounts of other olefins may be used, or isotactic polypropylene with small amounts of other polymers such as propylene-ethylene copolymer or propylene-butene-1 copolymer may be used. Olefin copolymers such as copolymers, polyethylene, polybutene-1, etc.) may be mixed. Various additives known to be added to isotactic propylene may also be added. The components constituting the opaque film layer (1) to (5) (FIGS. 6 to 10) are preferably a polymer blended with inorganic fine particles or pigments. 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. If this layer is to be an opaque layer, inorganic fine particles or pigments are further added. The base layer and the in-line composite film layer are laminated via an adhesive, and the lamination method is a thermoplastic resin extrusion sand lamination method, a dry lamination method using various adhesives, or a non-solvent lamination method. etc. are appropriate. Furthermore, in the lamination step, when the heat seal layer is coated with an adhesive layer, a laminated packaging material with good printing dimensional accuracy can be easily obtained. In addition, 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 is the thickness of the high melting point polyolefin film layer _C1 of the heat seal layer.
c ₁ , also low melting point polyolefin film layer C ₂
When the thickness of the low melting point polyolefin film layer is c ₂ , the thickness c ₂ of the low melting point polyolefin film layer needs to be in a range that satisfies a+b+c ₁ /15≦C ₂ ≦a+ _b +c 1 . Further, if necessary, a different type of film (for example, a polyvinylidene chloride layer, an ethylene vinyl acetate saponified layer, a vinylon layer, etc.) may be interposed between the base layer and the heat seal layer. Furthermore, it is more practically useful if the inner surface side of the base layer, that is, the adhesive layer side, is printed with the printing ink 6. The opaque laminated packaging material with the above structure uses a biaxially stretched polyester or nylon film or cellophane with excellent strength and heat resistance for the base layer, and an opaque biaxially stretched polyolefin-based inline composite film for the heat seal layer. Since I used
When forming a sealing layer of the same thickness, the laminated packaging material of the present invention has improved stiffness, transparency, strength, and moisture resistance compared to a conventional polyethylene heat sealing layer. When trying to achieve the same functionality, it is possible to maintain strength and protection even if the layer is made thinner than conventional sealing layers, and in addition, the sealing 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. Further, since the laminated packaging material of the present invention has an opaque film layer, ultraviolet rays are blocked, and deterioration of food due to oxidation, which is a problem in terms of food hygiene, is prevented.
Furthermore, conventionally, ultraviolet rays have been cut by performing white solid printing, but according to the present invention, the same effect can be achieved without going through such a process. In addition, especially when heat-sealing at a temperature that melts the high-melting point polyolefin film layer of the heat-sealing layer, the entire biaxially oriented polyolefin-based inline composite film is involved in the heat-sealing, which significantly increases the heat-sealing strength. It also has the characteristic that it can be made into something. Example 1 A 12μ polyethylene terephthalate biaxially stretched film (PET) was used as the base layer, and a composite film of a 30μ opaque biaxially stretched film made of polypropylene polyethylene and calcium carbonate and a polyethylene uniaxially stretched film was used as the heat seal layer. Using a laminated packaging material in which an opaque biaxially stretched film layer and a base layer are laminated with an isocyanate-based dry laminating adhesive (adhesive layer 1.5μ), a horizontal pillow packaging machine is used at a speed of 180
Boxes were packaged 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°C, the opaque biaxially stretched 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 with white solid printing EP: Uniaxially oriented ethylene/propylene copolymer film HP: Opaque biaxially oriented polypropylene inline composite film with heat sealability (polypropylene, A laminated film of EP and a biaxially stretched film obtained from polyethylene and calcium carbonate). OES: Biaxially oriented polyester film

【table】

[Table] As shown in the table above, the packaging material of the present invention has excellent opacity and is excellent in packaging speed, heat seal strength, and elasticity despite being thin. On the other hand, the sheet (2-1) of the comparative example lacks stiffness and does not increase the packaging speed. In Comparative Example (2-2), the packaging speed cannot be increased due to the lack of heat resistance of OPP. Comparative example (2
-3) has a thin heat-sealing layer and poor heat-sealing strength, making it less practical. 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 and C ₂ in the same figure are constructed as follows, and A,
The thickness of B was constant. A: Biaxially oriented polyester film (OES) B: Adhesive layer C ₁ : Biaxially oriented polypropylene film (OPP) C ₂ : Uniaxially oriented ethylene polypropylene copolymer film (EP) made opaque by blending titanium oxide

[Table] The results are shown in Table 3. As can be seen from Table 3, those that satisfied the condition a+b+c ₁ /15≦C ₂ ≦a+b+c ₁ gave good results in both seal strength and stiffness, but those that did not satisfy the condition, especially a+b+c ₁ / Those that do not satisfy 15≦c ₂ have a reduced sealing strength, and those that do not satisfy c ₂ ≦a+b+c ₁ have a reduced stiffness.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing an example of the opaque laminated packaging material of the present invention, FIGS. 2 to 5 are cross-sectional views showing examples, and FIGS.
The figure is a detailed view of the biaxially oriented polyolefin layer in FIGS. 2-5. A...Base layer, B...Adhesive layer, C...Heat seal layer, _C1 ...High melting point polyolefin film layer, C2...Low melting point polyolefin film layer, ₁ ...Base layer, 2... ...Biaxially stretched polyolefin layer, 3...Adhesive layer, 4...Polyolefin layer stretched at least uniaxially, 5...Layer with excellent adhesiveness stretched at least uniaxially, 21...
...opaque film layer, 22...transparent film layer.

Claims (1)

[Claims for Utility Model Registration] (1) A base layer consisting of a polyester or nylon biaxially oriented film or cellophane and an opaque biaxially oriented polyolefin inline composite film having heat sealability (a low melting point polyolefin film layer or At least one of the high melting point polyoffine film layers is made opaque by adding an inorganic substance or pigment.)
The thickness of the high melting point polyolefin film layer C ₁ of the biaxially oriented polyolefin inline composite film is c ₁ , and the same low melting point polyolefin film layer C is laminated using an adhesive. The thickness of ₂ is c ₂ ,
The thickness of base layer A is a, and the thickness of adhesive layer B is b.
A laminated packaging material characterized in that the following relational expression holds between the thicknesses of each layer, and the low melting point polyolefin film layer _C2 is disposed on the outer surface. a+b+c ₁ /15≦C ₂ ≦a+b+c ₁ (2) The opaque 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.