JP7181648B2 - Laminate film for liquid sealing - Google Patents

Description

The present invention proposes a laminate film suitable for use in liquid sealing, in which the squeezed position is heat-sealed while squeezing out the liquid to-be-packaged material remaining between two overlapping laminate films by means of a pair of heat seal rolls. is.

In the case of packaging bags made of plastic laminated film filled with a liquid to be packaged, if outside air (air), dust, etc. may be oxidized and the taste may deteriorate, or fungi may grow in the bag. Therefore, as a method of filling a liquid object to be packaged into a packaging bag without enclosing air or the like, as described in Patent Document 1, while filling the packaging bag with the object to be packaged, a horizontal seal roll is used. A method of squeezing out an excess amount of the packaged product and laterally sealing the squeezed-out position (hereinafter referred to as "submersible sealing method") is used. In addition, various types of filling and packaging machines using this in-liquid sealing method have been developed and are widely used (Patent Document 2, etc.).

JP-A-1-153410 Japanese Patent Application Laid-Open No. 2001-151208

In the liquid sealing method described in Patent Literature 1, when the object to be packaged consists only of a liquid, the object to be packaged can be hermetically filled without allowing outside air to enter. For example, when a solid substance (contaminant) is contained in an item to be packaged, such as a dressing, the solid substance may be caught in the sealed portion, and the caught portion may expand due to heating by the heat seal roll. As a result, there is a risk that large air bubbles will form and blister will occur, or that the sealed portion will peel off and the packaged item will leak out. Sealing materials and adhesives (such as instant adhesives) made of silicone have the property of reacting with moisture in the air and hardening. However, high viscosity materials such as silicone cannot be sufficiently squeezed out by heat sealing rolls. Since the sealing is inhibited, it has not been possible to carry out hermetically sealed packaging by means of the submerged sealing method.

Therefore, the present invention was developed to solve the problems of the conventional submerged seal filling method as described above. It is an object of the present invention to propose a laminate film that can be sealed in a liquid regardless of the type of a package that will be interposed in a heat-sealed portion, such as a highly viscous material such as a heat-sealed portion.

As a result of intensive studies to achieve the above object, the inventors have conceived of the present invention according to the gist and configuration described below.
That is, the present invention provides a laminate film used for liquid sealing in which a pair of heat-sealing rolls are used to squeeze out the liquid remaining between two laminated films and heat-seal the squeezed-out position to airtightly join them. comprising at least a base film layer and a sealant layer, wherein the sealant layer comprises a highly fluid thermoplastic resin film layer as an outermost layer and a highly fluid thermoplastic resin film layer on the base film layer side and a low-flow thermoplastic resin film layer laminated on the inner side, wherein the low-flow thermoplastic resin film layer has a higher melting point than the high-flow thermoplastic resin film layer , the melting point difference of which is 20° C. or more; When heated and pressurized by the heat seal roll, it softens and at the same time flows and is pushed out, and the low-fluidity thermoplastic resin film layer is pushed away from the high-fluidity thermoplastic resin film layer, The liquid-sealing laminate film is characterized in that the low-fluidity thermoplastic resin film layers facing each other are fusion-bonded to form a heat-sealed portion .

In addition, regarding the laminate film for sealing in liquid of the present invention,
(1) An aluminum foil, an aluminum alloy foil, an aluminum vapor deposition layer, an alumina vapor deposition layer, a silica vapor deposition layer, or an ethylene-vinyl alcohol copolymer resin layer is provided between the base film layer and the low-fluidity thermoplastic film layer. thing,
(2) the liquid is an aqueous or oily material, or these materials containing contaminants, heat-resistant materials, highly viscous materials, or other heat-sealing inhibitors;
(3) the high fluidity thermoplastic resin film layer has a thickness of 10 to 25 μm and is thinner than the low fluidity thermoplastic resin film layer;
(4) The highly fluid thermoplastic resin film layer is made of a low density polyethylene film, an ethylene/ethyl acrylate copolymer film, an ethylene/vinyl acetate copolymer film or an ethylene/acrylic acid copolymer film,
(5) the low-fluidity thermoplastic resin film layer is made of a high-density polyethylene film, a medium-density polyethylene film, or an ionomer film;
is the preferred solution.

In the liquid-sealing laminate film according to the present invention, as described above, the outermost layer of the sealant layer is composed of a highly fluid thermoplastic resin film layer, and the base film layer side of the highly fluid thermoplastic resin film layer and the A low-fluidity thermoplastic resin film layer is laminated on the inner side, and the low-fluidity thermoplastic resin film layer has a higher melting point than the high-fluidity thermoplastic resin film layer, and the melting point difference is 20 ℃ or more. Therefore, when such a laminate film is used, two laminate films are placed so that the sealant layers, that is, the outermost highly fluid thermoplastic resin film layers face each other when sealing in a liquid. When superimposed and heated and pressed by a pair of heat-sealing rolls, only the high-fluidity thermoplastic resin film layer softens due to the difference in fluidity (viscosity) and melting point, and flows to the heat-sealed position and its position. It will be pushed aside (excluded) together with the liquid matter that is the heat-seal-inhibiting substance that remains in the vicinity and intervenes. At the position where the high-fluidity thermoplastic resin film layer and the liquid have been pushed aside, the low-fluidity thermoplastic resin film layer located inside is exposed, and at the same time, the low-fluidity thermoplastic resin film layers are separated from each other. However, in a state in which a liquid substance, which is a heat-sealing inhibitor, is not interposed, fusion bonding (heat-sealing) is performed by heating and pressing with the heat-sealing roll.

Therefore, according to the present invention, the liquid material to be submerged seal-filled is a liquid material containing impurities such as solids, a highly viscous material with excellent heat resistance such as silicone, or a heat-resistant material that has difficult heat-sealing properties. material, i.e., a heat-sealing inhibitor, the liquid is surely pushed away together with the softened high-flow thermoplastic resin film layer, so that the liquid is caught in the heat-sealed portion. It is possible to reliably form a heat-sealed portion with high strength by means of the in-liquid sealing method without the risk of the heat-sealing being hindered.

In the present invention, the high-fluidity thermoplastic resin film layer is 10 to 25 μm thinner than the low-fluidity thermoplastic resin film layer, so that when sealing in liquid, the high-fluidity thermoplastic While only the resin film layer is softened and fluidized and displaced, the low-fluidity thermoplastic resin film layers can be fusion-bonded to each other, and this effect is achieved by high fluidity and low fluidity. It can also be adjusted by appropriately setting the type of the thermoplastic resin film layer and the heat sealing conditions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an embodiment of a laminate structure of a laminate film for sealing in liquid according to the present invention; It is a figure explaining the submerged sealing method using the laminated film for submerged sealing of this invention. 3 is an enlarged view showing a submerged seal position in FIG. 2; FIG.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a sectional view showing an embodiment of a laminate film for sealing in liquid according to the present invention.

As shown in FIG. 1, the laminate film 1 according to the present invention is basically composed of a base film layer 2 and a sealant layer 11 consisting of a low-flow thermoplastic resin film layer 3 and a high-flow thermoplastic resin film layer 4. It is configured. For example, a typical laminate structure of the laminate film 1 is such that a high fluidity thermoplastic resin film layer 4 is positioned as the outermost layer, and a low fluidity thermoplastic resin film is positioned as the inner layer (the inner side located on the side of the base film layer 2). It suffices if layer 3 is present.

In this laminate film 1, between the base film layer 2 and the sealant layer 11 (the low-fluidity thermoplastic resin film layer 3), an aluminum foil, an aluminum alloy foil, a vapor deposition layer of metal aluminum or its oxide is optionally provided. , a metal or metal oxide layer such as a deposited silica layer, or an intermediate layer made of a resin layer such as ethylene-vinyl alcohol copolymer (EVOH) having high gas barrier properties and water vapor barrier properties can be laminated.

In particular, when the material to be packaged (liquid material) to be sealed in a liquid has the property of being hardened by moisture contained in the outside air, such as silicone, it has a thickness of about 3 to 20 μm and is resistant to gas and other barrier properties. It is preferable to laminate excellent aluminum foil, metal aluminum, its oxide (alumina), or vapor deposition layer of silica. )/low fluidity polyolefin resin film layer 3/high fluidity thermoplastic resin film layer 4 and the like.

Examples of the method for producing the laminate film 1 include a dry lamination method, an extrusion lamination method, a co-extrusion method, and the like. The low fluidity thermoplastic resin film layer 3 and the high fluidity thermoplastic resin film layer 4 are laminated by an extrusion lamination method.

The base film layer 2 can be composed of uniaxially or biaxially oriented polyester (PET), nylon resin (NY), ethylene vinyl alcohol copolymer (EVOH), or the like, but is not limited thereto. , can be selected as appropriate.

A method of sealing and filling a liquid in a liquid without taking in outside air using the laminate film 1 having the above structure will be described with reference to FIG.
First, one laminate film 1 is folded in half at the central position so that the highly fluid thermoplastic resin film layers 4 face each other, or the laminate film 1 is stacked in two, and the side edges of the laminate film 1 are folded. are continuously heat-sealed in the vertical direction by vertical sealing rolls (not shown) to form a tubular shape.

This cylindrical laminate film 1 is sandwiched by a pair of heat seal rolls 5a and 5b over the entire width, and for example, the object to be packaged (liquid) is filled from a tank through a pump and a supply channel at a predetermined amount from a filling nozzle 6. while heating and pressurizing by a pair of heat seal rolls 5a and 5b. The heat seal rolls 5a and 5b in FIG. 2 are provided with a plurality of seal bars 7 (in the figure, 4). The facing seal bars 7 of the heat seal rolls 5a and 5b are pressed against each other so as to pinch the overlapping laminate films 1 together with the rotation of the heat seal rolls 5a and 5b, forming a heat seal portion 8 at the pressure contact portion. Thus, the package 9 is formed by airtightly packaging the liquid material to be packaged.

Here, when the overlapping laminate films 1 are sandwiched from both sides by the seal bars 7 as described above and heated and pressurized, the highly fluid thermoplastic resin film layer 4 located on the inner surface side is softened and simultaneously fluidized. Then, as shown in an enlarged view in FIG. 3, the surface of the laminate film 1 (high-fluidity thermoplastic resin film layer 4) and the liquid substance interposed in the vicinity thereof are sealed together with the rotation of the heat seal rolls 5a and 5b. A bank-like resin pool 10 is formed by being pushed away mainly upward from the bar 7 . As a result, at the displacement position of the high-fluidity thermoplastic resin film layer 4, the low-fluidity thermoplastic resin to which the heat seal inhibitor (liquid substance) located inside the high-fluidity thermoplastic resin film layer 4 does not adhere The film layer 3 is exposed to form a new surface, and the exposed low-fluidity thermoplastic resin film layers 3 are fusion-bonded (formation of the heat-sealed portion 8) in a state in which the liquid does not adhere.

Therefore, according to the submerged sealing method, even if the liquid contains solids (heat-sealing inhibitors), the solids are heat-sealed together with the highly fluid thermoplastic resin film layer 4 . Since the heat-sealed portion 8 is pushed upward, there is no risk of solid or liquid matter being caught in the heat-sealed portion 8 . Further, even when the liquid material is made of a heat-resistant, highly viscous material such as silicone, the liquid material adhering to the heat-sealed position of the laminate film 1 is extruded together with the highly fluid thermoplastic resin film layer 4. will be

As a result, even when a liquid substance or the like is interposed in the heat-sealed portion, the heat-sealing is not hindered, and the exposed low-fluidity thermoplastic resin film layers 3 are bonded together with high heat-sealing strength. can be fused and joined.

Therefore, the laminate film 1 of the present invention is suitable for liquid-sealing a liquid containing contaminants such as solids, a heat-resistant material that inhibits heat sealing, and a highly viscous material such as a sealing material or adhesive. can be used for

In the above-described submerged sealing method, only the high fluidity thermoplastic resin film layer 4 out of the sealant layer 11 is pushed away by heat and pressure by the seal bar 7, and at the same time, the inner lower layer exposed at the pushed-out position is removed. The heat-sealed portion 8 is formed by fusion bonding the fluid thermoplastic resin film layers 3 to each other. For this reason, depending on the film configuration (laminated structure) of the laminate film 1, etc., the sealing conditions such as the temperature and pressure of the heat seal rolls 5a and 5b, the low fluidity thermoplastic resin film layer 3 and the high fluidity thermoplastic resin Various conditions such as the type and thickness of the film layer 4 must be appropriately selected.

In particular, in the present invention, the thickness of the high fluidity thermoplastic resin film layer 4 is set to 10 to 25 μm, more preferably 10 to 20 μm, and the thickness of the high fluidity thermoplastic resin film layer 4 is set to the low fluidity heat. It is preferable to make it thinner than the plastic resin film layer 3 .
By setting the thickness of the highly fluid thermoplastic resin film layer 4 to 25 μm or less in this manner, the highly fluid thermoplastic resin film layer 4 is easily softened (viscosity is reduced) by heating and pressing from the seal bar 7 . can be forced to flow, i.e. to assist the pushing-apart action. In addition, the high-fluidity thermoplastic resin film layer 4 is softened at a low temperature, and it is sufficient if the liquid material adhering to the interface of the film layer 4 or intervening in the vicinity thereof can be reliably extruded (excluded). It is preferable to set the minimum thickness to 10 μm so that the effect can be exhibited.

In addition, the high-fluidity thermoplastic resin film layer 4 may be easily softened (lowered in viscosity) at a low temperature, and the thickness is preferably as thin as possible, whereas the low-fluidity thermoplastic resin film layer 3 It is preferable that the heat-sealing portion 8 formed at the push-out position has a thickness that can provide sufficient heat-sealing strength when used as a package or the like.

On the other hand, the low fluidity thermoplastic resin film layer 3 is heated at a higher temperature than the high fluidity thermoplastic resin film layer 4 by a pair of heat seal rolls 5a and 5b (the base film layer 2 is heated by the heat seal rolls 5a and 5b). Since it is heated from the side, the low-fluidity thermoplastic resin film layer 3 near the base film layer 2 is heated at a higher temperature than the high-fluidity thermoplastic resin film layer 4). It is preferable that the film layer 3 is thicker than the high fluidity thermoplastic resin film layer 4 so that the low fluidity thermoplastic resin film layer 3 does not become too thin due to heat sealing.

The thickness of the low-fluidity thermoplastic resin film layer 3 is not particularly limited. is 30 μm or more, more preferably 30 to 80 μm.

The low-fluidity thermoplastic resin film layer 3 is made of a material having a melting point higher than that of the high-fluidity thermoplastic resin film layer 4 by 20° C. or more. By providing a melting point difference of 20° C. or more between the low-fluidity thermoplastic resin film layer 3 and the high-fluidity thermoplastic resin film layer 4 in this way, high fluidity can be achieved by heating and pressurizing with the seal bar 7 as described above. It is possible to suppress softening and flowing of even the low-fluidity thermoplastic resin film layer 3 located inside the flexible thermoplastic resin film layer 4, and the heat-sealing conditions (temperature , pressure, etc.) can be easily adjusted.

In addition, the seal bar 7 preferably has a narrow seal surface so that the liquid substance interposed between the facing high-fluidity thermoplastic resin film layers 4 can be squeezed out with a high surface pressure, preferably 0.1 mm or more. It is preferable to set the distance to 5 mm, and to provide unevenness or an arc shape on the sealing surface.

As the low-fluidity thermoplastic resin film layer 3, it is preferable to use a polyolefin resin having a melting point of 105° C. or higher and 150° C. or lower. A film (IO) or the like can be used. On the other hand, as the highly fluid thermoplastic resin film layer 4, it is preferable to use a polyolefin resin having a melting point of 50° C. or more and less than 105° C. Examples include low-density polyethylene film (LDPE) and ethylene/ethyl acrylate copolymer. A combined film (EEA), an ethylene/vinyl acetate copolymer film (EVA), an ethylene/acrylic acid copolymer film (EAA), or the like can be used.

In the present invention, "fluidity" is represented by the relationship between the temperature or pressure and the viscosity when a thermoplastic resin is heated and melted and pressure is applied. In the plastic resin film, a "high-fluidity thermoplastic resin film layer" is defined as a "high-fluidity thermoplastic resin film layer" that has a reduced viscosity and is easy to flow at a temperature of less than 130 ° C., and a "high-fluidity thermoplastic resin film layer" is defined as a film that has a small decrease in viscosity and is difficult to flow at this temperature. low-fluidity thermoplastic resin film layer”.

For example, the high fluidity thermoplastic resin film layer has a melt flow rate (MFR) value of 7.0 g/10 min or more and less than 30 g/10 min, and the low fluidity thermoplastic resin film layer has a melt flow The rate (MFR) value is preferably 0.5 g/10 min or more and less than 7.0 g/10 min. The melt flow rate (MFR) is a value measured according to the method specified in JIS K7210 (1995).

INDUSTRIAL APPLICABILITY The present invention can be used to airtightly fill and package various liquid or viscous objects such as food and drink, pharmaceuticals, chemicals, and cosmetics.

1 laminate film 2 base film layer 3 low fluidity thermoplastic resin film layer 4 high fluidity thermoplastic resin film layers 5a, 5b heat seal roll 6 filling nozzle 7 seal bar 8 heat seal portion 9 package 10 resin reservoir 11 sealant layer

Claims (6)

A laminate film used for liquid sealing in which a pair of heat-sealing rolls is used to heat-seal the squeezed-out position while squeezing out the liquid material remaining between two overlapping laminate films to airtightly join them,
comprising at least a base film layer and a sealant layer;
The sealant layer comprises a high-fluidity thermoplastic resin film layer as the outermost layer, and a low-fluidity thermoplastic resin film layer laminated inside the high-fluidity thermoplastic resin film layer located on the base film layer side. and
The low-fluidity thermoplastic resin film layer has a higher melting point than the high-fluidity thermoplastic resin film layer, and the melting point difference is 20° C. or more,
The high-fluidity thermoplastic resin film layer is obtained by superimposing two sheets of the laminate film so that the high-fluidity thermoplastic resin film layers face each other, and heating and pressing with the pair of heat seal rolls. , which softens and simultaneously flows and is pushed aside,
In the low-fluidity thermoplastic resin film layer, the low-fluidity thermoplastic resin film layers facing each other are fusion-bonded to form a heat-sealed portion at the position where the high-fluidity thermoplastic resin film layer is displaced. A laminate film for sealing in liquid, characterized by : An aluminum foil, an aluminum alloy foil, an aluminum vapor deposition layer, an alumina vapor deposition layer, a silica vapor deposition layer, or an ethylene-vinyl alcohol copolymer resin layer is provided between the base film layer and the low-fluidity thermoplastic film layer. The laminate film for sealing in liquid according to claim 1. 3. The liquid according to claim 1 or 2, wherein the liquid is an aqueous or oily material, or these materials containing contaminants, a heat-resistant material, a highly viscous material, or other heat-sealing inhibitors. Laminate film for medium sealing. 4. The high fluidity thermoplastic resin film layer according to any one of claims 1 to 3, wherein the thickness is 10 to 25 μm and is thinner than the thickness of the low fluidity thermoplastic resin film layer. Laminate film for liquid sealing. The highly fluid thermoplastic resin film layer is made of a low-density polyethylene film, an ethylene-ethyl acrylate copolymer film, an ethylene-vinyl acetate copolymer film, or an ethylene-acrylic acid copolymer film. The laminate film for sealing in liquid according to any one of claims 1 to 4. 6. The submerged sealing laminate film according to any one of claims 1 to 5, wherein the low-fluidity thermoplastic resin film layer comprises a high-density polyethylene film, a medium-density polyethylene film, or an ionomer film.

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