JP7640336B2 - Packaging Materials - Google Patents

Description

The present invention relates to a new packaging material. In particular, the present invention relates to a packaging material to which the contents (packaged items) are less likely to adhere.

In the case of various products such as food, beverages, medicines, and cosmetics, various contents such as liquid and solid seasonings, yogurt, jelly, pudding, liquid detergent, toothpaste, retort foods, syrup, dressings, and facial cleansing creams are packaged in packages. These packages use packaging materials with functions according to the respective contents. Among these packaging materials, bags obtained by laminating resin films, aluminum foil, etc. are also widely used as one form of packaging material.

For example, in the case of food storage bags, seasonings such as soy sauce, sauces, ketchup, dressings, etc., bento boxes, side dishes, Western and Japanese sweets, ice cream, pet food, and other processed foods sold at convenience stores and supermarkets are packaged in a variety of packaging materials.

However, when using these packaging materials for seasonings that contain a large amount of water, such as soy sauce and sauces, some of the liquid adheres to the inner surface of the packaging material, making it difficult to remove the entire amount.

For this reason, various packaging materials have been proposed that prevent the contents, such as seasoning liquid, from adhering to the packaging material.

For example, a packaging material is known in which at least a base layer/thermal adhesive layer/anti-adhesive layer are laminated in this order, in which spherical or amorphous particles are dispersed on the surface of the thermal adhesive layer to form irregularities, the anti-adhesive layer is made of hydrophobic oxide fine particles and an inorganic binder resin, and is laminated so as to cover the irregularities, and the arithmetic mean roughness Ra of the surface of the anti-adhesive layer is greater than 5 μm (Patent Document 1).

For example, a method for providing a water-repellent laminate is known that includes the steps of preparing a first substrate and a second substrate, applying a coating liquid containing water-repellent fine particles to one surface of the first substrate, pressurizing and heating the first substrate and the second substrate so that the surface of the first substrate to which the coating liquid has been applied faces the second substrate, and laminating the first substrate and the second substrate, and peeling off the laminated first substrate and the second substrate (Patent Document 2).

JP 2014-46983 A JP 2019-63692 A

However, the packaging material in Patent Document 1 contains a binder in the water-repellent layer, and therefore is not sufficiently effective at preventing adhesion to, for example, foodstuffs that are high in moisture and viscosity. This makes it difficult to remove the contents from the bag, and even if the contents can be removed, some of the contents will remain attached to the inner surface of the bag, resulting in a large yield loss.

The packaging material described in Patent Document 2 provides a high adhesion prevention effect and high adhesive strength, but when some of the water-repellent layers are sealed together to form a bag, the water-repellent layers inhibit adhesion, making it difficult to obtain a seal strength sufficient for practical use, and there is a risk of the bag breaking during transportation or handling.

Moreover, even if these conventional packaging materials have good initial adhesion prevention effects immediately after production, the problem is that after filling the contents, the adhesion prevention properties deteriorate over time due to vibrations during transportation, etc., or due to the contents repeatedly colliding with the water-repellent layer.

Therefore, the main objective of the present invention is to provide a packaging material that has strong sealing properties and can maintain a high adhesion prevention effect even when in constant contact with liquid contents.

In light of these problems with the prior art, the inventors conducted extensive research and discovered that a packaging material with a specific structure can achieve the above objective, which led to the completion of the present invention.

1. A packaging material that can suppress or prevent adhesion of contents,
The present invention includes a thermally adhesive underlayer and a functional layer formed on at least a portion of a surface of the underlayer,
(1) The undercoat layer has an embossed structure in which a) an average height is 30 μm or more, b) the interval between adjacent projections is 250 μm or less, and c) the number of projections constituting the projections is 1.5×10 ⁷ to 5.5×10 ⁷ /m ² ,
(2) The functional layer contains hydrophobic particles in an amount of 0.4 to 1.5 g/ ^m2 by dry weight;
A packaging material characterized in that
2. The packaging material according to item 1, wherein the base layer has an area where a functional layer is formed and an area where a functional layer is not formed, and the surface of the base layer is exposed to the outside in the area where the functional layer is not formed.
3. A bag according to claim 1 or 2, in which the base layers of the packaging material are thermally bonded together.

The present invention provides a packaging material that has strong sealing properties and maintains a high level of adhesion prevention even when in constant contact with liquid contents.

In particular, the packaging material of the present invention can produce a bag having a functional layer formed on the uneven surface of a base layer that has a specific uneven structure in advance, making it possible to provide a bag with a more uniform adhesion prevention function throughout the entire bag (especially the corners) compared to a case in which a functional layer is formed in a later process.

Furthermore, when the packaging material of the present invention is formed into a bag so that the functional layer is disposed on the inner surface of the bag, even if liquid contents are constantly in contact with the functional layer, the contents can be repelled due to the water repellency and other properties of the functional layer, and the contents can be removed with almost no residue remaining. Therefore, even if food such as seasoning liquid is contained in the bag in a state where it is constantly in contact with the contents, adhesion of the seasoning liquid to the inner surface of the bag can be effectively suppressed or prevented. In particular, as described above, since the functional layer is formed on the uneven surface of the base layer having a specific uneven structure, the functional layer can withstand vibrations during transportation or collisions with the contents, and as a result, an excellent adhesion prevention effect can be maintained.

At the same time, the packaging material of the present invention also has excellent sealing strength, so the contents of the product containing the bag made of the material can be more reliably maintained during storage, transportation, and use.

Packaging materials with these characteristics can be widely used as storage bags for food, medicines, cosmetics, industrial products, etc.

FIG. 1 is a schematic diagram showing a basic layer structure of a packaging material of the present invention. 1A to 1C are diagrams showing an example of a procedure for producing a bag using the packaging material of the present invention. 1 is a schematic diagram of a three-sided bag made using the packaging material of the present invention. FIG. 2 is a schematic diagram of a bag body (connected body) produced in the examples.

1. Packaging material (material of the present invention)
The material of the present invention is a packaging material that can suppress or prevent adhesion of contents,
The present invention includes a thermally adhesive underlayer and a functional layer formed on at least a portion of a surface of the underlayer,
(1) The undercoat layer has an embossed structure in which a) an average height is 30 μm or more, b) the interval between adjacent projections is 250 μm or less, and c) the number of projections constituting the projections is 1.5×10 ⁷ to 5.5×10 ⁷ /m ² ,
(2) The functional layer contains hydrophobic particles in an amount of 0.4 to 1.5 g/ ^m2 by dry weight;
It is characterized by:

(A) Basic Layer Structure A typical layer structure of the material of the present invention is shown in Figure 1. The material of the present invention 10 has a base layer 11 having an embossed structure with a concave-convex surface, and a functional layer 12 containing hydrophobic fine particles 12a formed on the concave-convex surface of the base layer 11. The material of the present invention may also have a base layer 13 as a lower layer of the base layer 11, as shown in Figure 1.

As shown in FIG. 1, it is preferable that the hydrophobic microparticles 12a are adhered to each other to form a three-dimensional mesh structure, forming a porous layer. This makes it possible to achieve a higher adhesion prevention effect.

It is preferable that each layer is laminated in direct contact with each other, but other layers may be included as long as they do not impede the effects of the present invention. Each layer is described below.

(B) Regarding Each Layer Substrate Layer The substrate layer is an optional layer, but can be suitably used as a layer for supporting the underlayer.

As the base layer, although not limited thereto, a resin film (also called a "resin-based base film") can be suitably used. There is no particular limit to the resin material, and resin components used in publicly known or commercially available bags can be used. Therefore, for example, at least one type of synthetic resin can be used.

Examples of the above synthetic resins include polyester-based resins such as polyethylene terephthalate (PET) and polybutylene terephthalate, polyolefin-based resins such as polystyrene, polyethylene, and polypropylene, polyamide-based resins such as nylon 6 and nylon 66, and vinyl chloride-based resins such as polyvinylidene chloride and polyvinyl chloride. These resins may be either homopolymers or copolymers. For example, as polyolefin-based resins, copolymers made of copolymers of olefin monomers can be preferably used, but they may also be copolymers with monomers other than olefins as long as they do not interfere with the effects of the present invention.

In the present invention, it is preferable that the material contains at least one synthetic resin selected from the group consisting of polyester resin and polyamide resin. For example, polyethylene terephthalate, nylon 6, nylon 66, etc. can be preferably used. Any of these may be publicly known or commercially available.

The resin film may be any film containing the above-mentioned resin component as the main component (usually 50% by weight or more, preferably 80% by weight or more, and more preferably 95 to 99% by weight), but may also contain other components (fillers, colorants, antistatic agents, ultraviolet absorbers, oxygen absorbers, etc.) within the range that does not impede the effects of the present invention. For example, the film may be a mixed resin film containing other resin components, or a polymer alloy film, etc.

The resin film may be either unstretched or stretched. For example, in the case of food and eating applications where strength, heat resistance, etc. are important, a stretched film (particularly a biaxially stretched film) is preferable. In the present invention, a biaxially stretched polyethylene terephthalate film can be preferably used mainly from the viewpoint of sealability (heat resistance), printability, etc.

The resin film may be a single layer type, or a multi-layer type in which multiple layers are laminated. In the case of a multi-layer type, a structure in which multiple films are laminated together can improve, for example, antibacterial properties, gas barrier properties, oxygen and moisture absorbency, etc., and is therefore desirable in terms of providing higher added value.

As a multi-layer type film, for example, a laminate in which one or more other layers are formed on at least one surface of a polyethylene terephthalate film or a polyolefin film can be used as a resin-based substrate film. Examples of the other layers include a printed layer, an overcoat layer, an adhesive layer, a primer coat layer, an anchor coat layer, an anti-slip layer, a lubricant layer, an anti-fogging agent layer, a gas barrier layer, a humidity control layer, a gas absorbing layer, etc. Therefore, for example, a printed layer, an overcoat layer, etc., or various films can be appropriately laminated on the surface of the resin film opposite the surface that contacts the contents (i.e., the surface that is exposed to the outside when sealed into a bag).

In particular, in the present invention, when a biaxially oriented polyethylene terephthalate film or a biaxially oriented polystyrene film is used as the resin film, it can be used in either a single-layer or multilayer form. In particular, as a multilayer type film, for example, a laminate including a biaxially oriented polyethylene terephthalate film or a polystyrene film and a heat seal layer formed on at least one surface of the film can be suitably used as the resin base film. For example, when a biaxially oriented polyethylene terephthalate film is used as the base material, a laminate including a printing layer, an adhesive layer, and a biaxially oriented polyethylene terephthalate film in this order can be suitably used as the resin film.

When forming the adhesive layer, the adhesive that can be used is not limited as long as it can be used for food applications, and for example, a laminating adhesive can be suitably used. Examples of components of laminating adhesives include polyester-based adhesives, polyether-based adhesives, and polyurethane-based adhesives.

The adhesive properties are not particularly limited, and any of solvent-based, solventless, and water-based adhesives can be used. For example, in the present invention, a laminate formed by laminating two or more polyethylene terephthalate films with a polyurethane-based laminate adhesive layer between them can be suitably used as the resin-based substrate film. If necessary, the film can be coated with a coating liquid containing hydrophobic particles, dried, and then laminated on the opposite side to another substrate before being made into a bag.

In the present invention, the underlayer is interposed between the resin-based substrate film and the functional layer, and a fine uneven shape is formed on the surface of the underlayer, thereby improving the formation area of the functional layer and the fixing power of the functional layer. In addition, the contact area between the contents and the inner surface of the bag can be reduced by the synergistic action of the uneven shape and the water repellency, so that a higher non-adhesiveness can be obtained.

The undercoat layer has an embossed structure in which a) the average height is 30 μm or more, b) the spacing between adjacent projections is 250 μm or less, and c) the number of projections constituting the projections is 1.5×10 ⁷ to 5.5×10 ⁷ /m ² .

The average height of a) is usually 30 μm or more, and preferably 30 to 100 μm. The average height is measured by exposing the cross section using a microtome to prepare five cross section samples, which are then observed under a microscope. Each cross section sample is observed under an optical microscope, and one arbitrarily selected point on the cross section is observed to measure the height difference between the concave and convex parts. If there is a difference in height between the concave parts on both ends of the convex part, the height difference is measured using the lower one as the standard. The arithmetic mean value of the total value of the above 1 point x 5 can be regarded as the "average height".

The spacing between adjacent irregularities in b) is 250 μm or less, and preferably 1 to 250 μm. The method for measuring the spacing between irregularities is to observe the produced film under a microscope, observe 10 vertices of convexities arbitrarily selected within one field of view, and measure the distance from one vertex to the vertex of the furthest convexity. The arithmetic average of these values can be regarded as the "spacing between irregularities."

The number of convex portions constituting the unevenness of c) is 1.5×10 ⁷ to 5.5×10 ⁷ /m ² , and preferably 1.8×10 ⁷ to 5.2×10 ⁷ /m ^2. The number of convex portions can be measured by observing the produced film with a microscope, measuring the length of the diagonal (vertical a, horizontal b) of one convex portion in a planar view arbitrarily selected within the field of view, and calculating the number of convex portions per m ² by considering the convex portion as a square prism and calculating the area of one convex portion (a×b).

By providing an embossed structure that satisfies all of the above conditions a) to c), it is possible to reliably achieve high heat sealability as well as a long-lasting anti-adhesion effect (e.g. water repellency).

As the resin component contained in the undercoat layer, adhesives containing known resin components with adhesive properties can be used. For example, components used in known or commercially available sealant films, as well as adhesives such as lacquer-type adhesives, easy-peel adhesives, and hot-melt adhesives can be used.

Specific examples of adhesive resin components include, but are not limited to, adhesives such as polyolefin resins, polyester resins, polyurethane resins, epoxy resins, acrylic resins, and vinyl resins. More specifically, examples include a) polyolefin resins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic acid copolymer, acrylic-vinyl chloride-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, methyl pentaethylene polymer, polybutene polymer, polyethylene, and polypropylene; b) acid-modified polyolefin resins obtained by modifying these polyolefin resins with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid; and c) polyvinyl acetate resins, poly(meth)acrylic resins, polyacrylonitrile resins, and polyvinyl chloride resins. Further examples include blend resins of these, copolymers containing combinations of the monomers that make up these, modified resins, etc.

The content of the adhesive resin component in the undercoat layer may be set appropriately depending on the type of adhesive resin component used, and may be, for example, about 60 to 97% by weight, but is not limited to this. Therefore, it may be set to about 70 to 90% by weight.

In addition, a sealant film composed of the above adhesive resin component may be attached via the adhesive layer shown in the "substrate layer" above.

As a method for forming fine irregularities on the surface of the underlayer, embossing can be suitably used, although it is not limited thereto. Examples of embossing methods include the following. For example, a) when the sealant layer resin is extruded, it is pressed and cooled using a cooling roll with an embossed engraving on its surface to form the embossment, b) after forming the underlayer, the film is pressed and molded with a roll with an embossed engraving on its surface while heating, and then cooled, and c) a method in which the underlayer film is embossed and then bonded together.

The embossing pattern is not particularly limited as long as the desired unevenness is formed, and various patterns such as stripes, lattices, dots, etc. can be used.

Functional layer The functional layer functions as an adhesion prevention layer by exerting water repellency. For this purpose, it contains hydrophobic fine particles. This gives the material of the present invention water repellency, and adhesion can be more effectively suppressed or prevented even if the contents are high in moisture and viscosity. Specifically, when the contents to be put into a bag made of the material of the present invention are foods that are low in fat and high in moisture, it is sufficient to coat the surface of the base layer with hydrophobic fine particles.

There are no particular limitations on the hydrophobic particles, but when a bag made of the material of the present invention is used as a food container, hydrophobic microparticles with a primary particle size of nano size are preferably used because they are suitable for food use.

The hydrophobic fine particles are not particularly limited, but at least one type of particles (powders) such as silicon oxide, titanium oxide, aluminum oxide, and zinc oxide can be suitably used. Silicon oxide particles are more preferable. These particles preferably have an average primary particle size of 5 to 50 nm, and more preferably 7 to 30 nm.

The hydrophobic microparticles preferably form a porous layer having a three-dimensional mesh structure, the thickness of which is preferably about 0.1 to 5 μm, and more preferably about 0.2 to 2.5 μm. By adhering in such a porous layer state, the layer can contain a large amount of air, and can exhibit better non-adhesive properties.

The average primary particle diameter of hydrophobic microparticles can be measured using a transmission electron microscope or a scanning electron microscope. More specifically, the average primary particle diameter can be determined by taking a photograph using a transmission electron microscope or a scanning electron microscope, measuring the diameters of 200 or more particles on the photograph, and calculating the arithmetic mean value.

The content of hydrophobic particles in the functional layer is not limited, but is usually preferably 10 to 100% by weight. The closer the content of these particles is to 100% by weight, the higher the water repellency can be obtained.

The method for forming the functional layer is not particularly limited, but is preferably carried out by a method including a step of applying a dispersion liquid (coating liquid) in which hydrophobic particles are dispersed in a solvent to a part or all of the surface of the base layer and drying. In order to form a homogeneous functional layer, it is preferable to disperse aggregates in the coating liquid before application.

The solvent used in the coating liquid is not particularly limited, and one or more solvents used in food manufacturing, such as water, ethanol, etc., can be used.

There are no particular restrictions on the amount of hydrophobic microparticles contained in the coating liquid, but it is generally preferable to set the amount appropriately within the range of approximately 2 to 200 g/L (liter).

The method for applying the coating liquid onto the undercoat layer is not particularly limited, and known methods such as roll coating, gravure coating, bar coating, doctor blade coating, comma coater, brush coating, etc. can be appropriately adopted. Note that the hydrophobic fine particles can be applied more uniformly if they are mixed in a dispersion medium. In the case of gravure coating, it is preferable to use a plate that is preliminarily designed not to apply the coating liquid to the sealing portion so that the functional layer is not formed on the sealing portion.

The coating amount (weight after drying) can be appropriately set according to the desired water repellency, but is usually about 0.4 to 1.5 g/m ² , and preferably 0.6 to 1.0 g/m ^2. By setting it within the above range, a porous layer made of anti-adhesion particles can be more reliably formed, resulting in more excellent non-adhesion properties being obtained for a long period of time, and being more advantageous in terms of preventing the fine particles from falling off, costs, etc.

After coating, the coated surface is dried to obtain a film with the anti-adhesion particles adhered to the resin-based substrate film. There are no particular limitations on the drying method, and either natural drying or heat drying may be used. When heat drying is used, a temperature of 60 to 190°C, particularly 80 to 150°C, is usually sufficient. The heating time may be set appropriately depending on the heating temperature, etc., but is usually about 3 to 30 seconds.

The water repellency of the coating surface is preferably such that the contact angle with pure water (25°C) is 140 degrees or more, and particularly 150 degrees or more.

2. Method for Producing Packaging Material The material of the present invention can be produced by forming each layer and laminating them as explained in "1. Packaging material" above.

Each layer can be formed by, for example, laminating preformed films or applying a coating liquid.

The lamination of each layer is not limited, and any method can be used as appropriate, such as bonding via an adhesive layer, laminating by simultaneous extrusion molding, or applying a coating liquid to each layer. These methods can also be used in combination.

3. Use of Packaging Materials The material of the present invention can be used in the same manner as general packaging materials, but is particularly suitable for use in packaging where the packaged item is in contact with the functional layer.

The form of packaging is not limited, and may be any of the following: a packaging sheet, a container, or a bag. In these cases, it is preferable to design the container, bag, or other inner surface so that the packaged item is in contact with the functional layer.

The bag body is not particularly limited in its shape, and may be, for example, a two-sided bag, a three-sided bag, a pillow bag (a folded bag), a gusset bag, a bottom gusset bag, a pouch (standing pouch), a stand-up zipper bag, a side-sealed bag, a bottom-sealed bag, etc.

Figure 2 shows an example of making a three-sided bag using the material of the present invention. Figure 2A is a plan view, and Figure 2B is a side view. Two rectangular sheets of the material of the present invention 10, 10 shown in Figures 2A and 2B are prepared. Next, as shown in Figure 2C, they are stacked so that their functional layers face each other. In this state, the heat seal area S is bonded by thermocompression bonding a predetermined heat seal area S. In this case, too, the functional layer 12 is embedded in the base layer by thermocompression bonding, exposing the base layer, and the base layers of the two sheets of the material of the present invention are bonded together.

As a result, a three-sided bag can be produced with the heat-sealed area S bonded, as shown in Figure 3A. Figure 3B shows the state as viewed from the side (opening) of Figure 3A. As shown in Figure 3B, the contents (packaged items) can be filled into the spatial area (opening) a. After filling with the contents, the functional layers of the opening can be pressed together and heat-sealed in the same manner as above, thereby sealing the contents.

The functional layer on the heat seal area S is buried in the base layer during heat sealing, but the functional layer in other areas is left exposed. Therefore, the inner surface of the spatial area a of the bag is substantially entirely covered with the functional layer 12. As a result, even if the contents are in contact with the functional layer 12 while they are stored, when the contents are removed, they are repelled by the functional layer 12 and almost all of them can be removed.

In this invention, "sealed" refers to a state in which the inside and outside of the package are substantially sealed off. Therefore, for example, as long as the contents do not leak out, the entry and exit of small amounts of gas is permitted.

The packaged items are not particularly limited, and the bag can be used to package foods, chemicals, medicines, cosmetics, and other items. It is particularly suitable for packaging liquid items that require anti-adhesion properties. For example, the bag can be used to store liquid seasonings such as soy sauce, sauces, dressings, and sauces.

The following examples and comparative examples are presented to more specifically explain the features of the present invention. However, the scope of the present invention is not limited to the examples.

Example 1
(1) Preparation of intermediate layer/underlayer A film to be a coat underlayer was prepared using a T-die extruder. A biaxially oriented polyethylene terephthalate film (hereinafter referred to as "12 μm PET") having a thickness of 12 μm was used as the base layer. A linear low density polyethylene (hereinafter referred to as "25 μm LLDPE") having a thickness of 25 μm was laminated on this PET as an intermediate layer, and then a linear low density polyethylene (hereinafter referred to as "85 μm LLDPE") having a thickness of 85 μm was extruded from a T-die as a underlayer on the LLDPE to form a film, and the film was pressed and cooled with a cooling roll engraved with an embossed shape. In this way, a laminate consisting of "base layer PET 12 μm/intermediate layer LLDPE 25 μm/underlayer LLDPE 85 μm" (unevenness height 30 μm, unevenness apex spacing (film flow direction) 130 μm, unevenness apex spacing (film width direction) 150 μm) was produced.
(2) Formation of functional layer 7 g of commercially available hydrophobic silica particles (average primary particle diameter: 7 nm) was added as hydrophobic oxide fine particles to 93 g of ethanol, and the mixture was stirred at room temperature for 30 minutes to prepare a water-repellent coating liquid. This coating liquid was applied to the surface of the base layer of the laminate so that the weight after drying was 0.6 g/ ^m2 , and then the mixture was heated and dried in an oven at 160°C for 10 seconds (3 m/min) to evaporate the ethanol, forming a functional layer, and a packaging material (strip with a width of 150 mm) was obtained.
(3) Filling and Bag-Making Step Using the above packaging material, bags were made while continuously filling 10 g of commercially available soy sauce (Kikkoman Foods' dark soy sauce) using a liquid/viscous material filling machine.
More specifically, the packaging material was folded in the longitudinal direction to form a cylinder so that the functional layers face each other, and then folded in the longitudinal direction to form a cylinder by applying a vertical seal, and soy sauce was sequentially poured into the cylinder from a nozzle while applying a horizontal seal while pinching the soy sauce, thereby sealing three sides as shown in Figure 4 to produce a connected body 40 (bag sample) of soy sauce in a bag. The connected body 40 has a horizontal seal 41 perpendicular to the fold 43 and a vertical seal 42 parallel to the fold 43, and the seals are filled with soy sauce 44 as the content.
The vertical seal conditions were a temperature of 135°C and a pressure of 80 kPa left/50 kPa right. The horizontal seal conditions were a temperature of 132°C and a pressure of 380 kPa left/340 kPa right. The seal width was 8 mm for the vertical seal and 13 mm for the horizontal seal. The molded bag size was 47 mm long x 75 mm wide (including seal width) with a three-sided seal, and the filling speed was 5 m/min (bag making capacity 108 bags/min). The seal width was 8 mm for the vertical seal and 13 mm for the horizontal seal.

Example 2
In the above (2) formation of the functional layer, the packaging material was prepared so that the functional layer would not be formed in the horizontal seal portion. Except for this, the packaging material was prepared in the same manner as in Example 1, and bag samples were produced by carrying out the filling and bag making process.

Example 3
In the above (1) preparation of the intermediate layer/base layer, a bag sample was obtained in the same manner as in Example 1, except that the base layer surface had an irregularity height of 40 μm, an irregularity apex spacing (film flow direction) of 230 μm, and an irregularity apex spacing (film width direction) of 240 μm.

Comparative Example 1
A bag sample was obtained in the same manner as in Example 1, except that in the above (1) preparation of the intermediate layer/undercoat layer, the layers were pressed and cooled using a smooth cooling roll.

Comparative Example 2
A bag sample was obtained in the same manner as in Example 1 except that in the above (1) preparation of the intermediate layer/underlayer, the height of the projections and recesses on the underlayer surface was set to 20 μm.

Comparative Example 3
A bag sample was obtained in the same manner as in Example 3 except that in the above (1) preparation of the intermediate layer/underlayer, the height of the projections and recesses on the underlayer surface was set to 20 μm.

Comparative Example 4
In the above (1) preparation of the intermediate layer/base layer, the base layer surface had an irregularity height of 30 μm, an irregularity apex spacing (film flow direction) of 290 μm, and an irregularity apex spacing (film width direction) of 290 μm. Except for the irregularity shape, a bag sample was obtained in the same manner as in Example 1.

Comparative Example 5
A bag sample was obtained in the same manner as in Example 1, except that in the above (2) formation of the functional layer, the functional layer was coated so that the weight of the functional layer after drying was 2.0 g/ ^m2 .

Comparative Example 6
A bag sample was obtained in the same manner as in Example 1, except that in the above (2) formation of the functional layer, the functional layer was coated so that the weight of the functional layer after drying was 0.3 g/ ^m2.

Test Example 1
The bag samples obtained in each of the Examples and Comparative Examples were evaluated as follows. Table 1 shows the surface roughness and test results of each sample.

(1) Initial water repellency A micropipette tip (Ibis pipette tip, Ibis) 40 was attached to a micropipette (pipetman P20, Gilson) and Kikkoman Foods' dark soy sauce was gently dropped onto the surface of the sample before bagging. Samples that slid down smoothly when tilted were evaluated as "○", and samples that showed even a partial adhesion were evaluated as "×".

(2) Water repellency retention The water repellency retention test was carried out on the bag samples obtained in the examples and comparative examples. Specifically, the prepared bag samples were vibrated for 1 minute 40 seconds (10 Hz-10 seconds, 15 Hz-10 seconds, 20 Hz-10 seconds, 25 Hz-10 seconds, and 30 Hz-10 seconds, repeated twice, with up and down reciprocating vibration) under conditions of 2.2 mm amplitude (vertical direction) and acceleration of about 2G using a vibration tester (IDEX Corporation TRANSPORTATION TESTER BF-30U), and then the bag samples were opened with fingers, and the soy sauce (adhered area) attached to the inner surface of the bag sample was visually judged. On the surface in contact with the contents, samples with an adhesion area of 0 to less than 10% were marked with "◎", samples with an adhesion area of 10 to less than 30% were marked with "○", and samples with an adhesion area of 30 to 100% were marked with "×".

(3) Transportation test A water repellency maintenance test was carried out on the bag samples obtained in the examples and comparative examples. Specifically, the prepared bag samples were vibrated for 1 minute 40 seconds (10 Hz-10 seconds, 15 Hz-10 seconds, 20 Hz-10 seconds, 25 Hz-10 seconds, and 30 Hz-10 seconds, repeated twice, with up and down reciprocating vibration) using a vibration tester (IDEX TRANSPORTATION TESTER BF-30U), under conditions of 2.2 mm amplitude (vertical direction) and acceleration of about 2G, and then the bag samples were opened with fingers, and the soy sauce (adhered area) attached to the inner surface of the bag sample was visually judged. On the surface in contact with the contents, samples with an adhesion area of 0 to less than 10% were marked as "◯", samples with an adhesion area of 10 to less than 30% were marked as "△", and samples with an adhesion area of 30 to 100% were marked as "X".

(4) Pressure test (seal strength)
A pressure resistance test was conducted to evaluate the sealing property of the bag samples obtained in the examples and comparative examples. The bag samples were clamped in a pressure device, and a load of 100 kgf/bag was applied for 1 minute, after which the sealed portions of the bag samples were visually inspected. If the sealed portion did not recede and there was no change in appearance, the sample was rated as "◎", if the sealed portion receded but the bag did not break, the sample was rated as "○", and if the bag broke, the sample was rated as "×".

As is clear from the results in Table 1, in the examples having a base layer with a predetermined unevenness, it is possible to achieve excellent water repellency as well as high seal strength.

Claims (3)

A packaging material that can suppress or prevent adhesion of contents,
The present invention includes a thermally adhesive underlayer and a functional layer formed on at least a portion of a surface of the underlayer,
(1) The undercoat layer has an embossed structure in which a) an average height is 30 μm or more, b) the interval between adjacent projections is 250 μm or less, and c) the number of projections constituting the projections is 1.5×10 ⁷ to 5.5×10 ⁷ /m ² ,
(2) The functional layer contains hydrophobic fine particles having a primary average particle size of 5 to 50 nm in an amount of 0.4 to 1.5 g/ ^m2 by dry weight ,
(3) The functional layer is a porous layer in which a plurality of the hydrophobic particles are fixed to each other to form a three-dimensional network structure.
A packaging material characterized in that The packaging material according to claim 1, wherein the base layer has an area where a functional layer is formed and an area where a functional layer is not formed, and the surface of the base layer is exposed to the outside in the area where the functional layer is not formed. A bag body in which the base layers of the packaging material according to claim 1 or 2 are thermally bonded together.