Packaging Materials

Abstract

To provide a packaging material that can exhibit high anti-stick effect even if a liquid content is always in contact while having strong sealability.SOLUTION: There is provided a packaging material capable of suppressing or preventing a content from sticking. The packaging material includes a ground layer with thermal adhesive properties, and a functional layer formed at least in a part of a surface of the ground layer, wherein: (1) the ground layer has an embossed structure such that a) an average height is 30 μm or more, b) a mutually adjacent unevenness interval is 250 μm or less, and c) the number of projections constituting the unevenness is 1.5×107 to 5.5×107 pieces / m2; and (2) the functional layer contains 0.4-1.5 g / m2 of hydrophobic particulates in terms of dry wet.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a novel packaging material. In particular, the present invention relates to a packaging material to which contents (packaged items) are less likely to adhere. [Background technology]

[0002] In 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, dressing, and facial cleansing cream are packaged in packages. These packages use packaging materials with functions according to the contents. Among these packaging materials, bags obtained by laminating resin films, aluminum foil, etc. are also widely used as one form of packaging material.

[0003] Taking food storage bags as an example, 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, supermarkets, etc. are packaged in a variety of packaging materials.

[0004] However, among these packaging materials, when it comes to seasoning liquids 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.

[0005] For this reason, various packaging materials have been proposed that prevent the contents, such as seasoning liquid, from adhering to the packaging material.

[0006] For example, a packaging material is known in which at least a base layer / thermal adhesive layer / anti-adhesion 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-adhesion layer is made of hydrophobic oxide microparticles 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-adhesion layer is Ra>5 μm (Patent Document 1).

[0007] Also, for example, there is known a method for providing a water-repellent laminate by a manufacturing method including 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, thereby laminating the first substrate and the second substrate; and peeling off the laminated first substrate and the second substrate (Patent Document 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2014-46983 A [Patent Document 2] JP 2019-63692 A Summary of the Invention [Problem to be solved by the invention]

[0009] However, the packaging material of Patent Document 1 contains a binder in the water-repellent layer, and therefore is not sufficiently effective in 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.

[0010] The packaging material described in Patent Document 2 provides a high anti-adhesion 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.

[0011] Furthermore, even if these conventional packaging materials have good initial anti-adhesion properties immediately after production, there is a problem in that after the contents are filled, the anti-adhesion properties deteriorate over time due to vibrations during transportation, etc., or due to the contents repeatedly colliding with the water-repellent layer.

[0012] Therefore, a main object 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 it is constantly in contact with liquid contents. [Means for solving the problem]

[0013] In view of these problems in the prior art, the present inventors conducted extensive research and discovered that a packaging material having a specific structure can achieve the above object, thereby completing the present invention.

[0014] 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 underlayer has a) an average height of 30 μm or more, b) an interval between adjacent irregularities of 250 μm or less, and c) the number of protrusions constituting the irregularities is 1.5×10 7 ~5.5×10 7 pieces / m 2 The embossed structure is (2) The functional layer contains hydrophobic particles in an amount of 0.4 to 1.5 g / m2 in terms of dry weight. 2 include, A packaging material characterized by: 2. A packaging material as described in item 1, having an area on the base layer where a functional layer is formed and an area where the functional layer is not formed, and in the area where the functional layer is not formed, the surface of the base layer is exposed to the outside. 3. A bag body as described in paragraph 1 or 2 above, in which the base layers of the packaging material are thermally bonded together. Effect of the Invention

[0015] According to the present invention, it is possible to provide a packaging material that has strong sealing properties and can maintain a high adhesion prevention effect even when it is constantly in contact with liquid contents.

[0016] In particular, with the packaging material of the present invention, a bag can be produced having a functional layer formed on the uneven surface of a base layer having a specific uneven structure in advance, thereby providing a bag with more uniform anti-adhesion function throughout the entire bag (especially the corners) compared to a case in which a functional layer is formed in a later process.

[0017] Furthermore, when the packaging material of the present invention is formed such that the functional layer is disposed on the inner surface of the bag, even if the liquid contents are constantly in contact with the functional layer, the contents can be repelled due to the water repellency of the functional layer, and the contents can be removed with almost no residue. Therefore, even if a food such as a seasoning liquid is stored in the bag in a state where it is constantly in contact with the functional layer, the adhesion of the seasoning 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 vibration during transportation or collision with the contents, and as a result, an excellent adhesion prevention effect can be maintained.

[0018] At the same time, the packaging material of the present invention has excellent seal strength, so that the contents can be more reliably maintained throughout the storage, transportation and use of products including bags using the material.

[0019] Packaging materials with such characteristics can be widely used as containers for medicines, cosmetics, industrial products, and the like, in addition to food. [Brief description of the drawings]

[0020] [Figure 1]FIG. 1 is a schematic diagram showing a basic layer structure of a packaging material of the present invention. [Diagram 2] 1A to 1C are diagrams showing an example of a procedure for producing a bag using the packaging material of the present invention. [Diagram 3] 1 is a schematic diagram of a three-sided bag made using the packaging material of the present invention. [Figure 4] FIG. 2 is a schematic diagram of a bag body (connected body) produced in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] 1. Packaging materials (materials 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 underlayer has a) an average height of 30 μm or more, b) an interval between adjacent irregularities of 250 μm or less, and c) the number of protrusions constituting the irregularities is 1.5×10 7 ~5.5×10 7 pieces / m 2 The embossed structure is (2) The functional layer contains hydrophobic particles in an amount of 0.4 to 1.5 g / m2 in terms of dry weight. 2 include, It is characterized by:

[0022] (A) Basic layer composition 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 layer below the base layer 11, as shown in Figure 1.

[0023] In addition, as shown in Fig. 1, it is preferable that the hydrophobic fine particles 12a are fixed to each other to form a three-dimensional network structure, forming a porous layer, which can achieve a higher adhesion prevention effect.

[0024] Although it is preferable that the layers are laminated in a state where they are in direct contact with each other, other layers may be included within the scope that does not impair the effects of the present invention. Each layer will be described below.

[0025] (B) About each layer Base material layer The substrate layer is an optional layer, but can be suitably used as a layer for supporting the undercoat layer.

[0026] The base layer is preferably made of, but not limited to, a resin film (also called a "resin-based base film"). The resin material is not particularly limited, and any resin component that is used in known or commercially available bags can be used. Thus, for example, at least one type of synthetic resin can be used.

[0027] Examples of the synthetic resin include polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate, polyolefin resins such as polystyrene, polyethylene, and polypropylene, polyamide resins such as nylon 6 and nylon 66, and vinyl chloride resins such as polyvinylidene chloride and polyvinyl chloride. These resins may be either homopolymers or copolymers. For example, as the polyolefin resin, a copolymer made of a copolymer of an olefin monomer can be suitably used, but it may also be a copolymer with a monomer other than olefin within a range that does not impair the effects of the present invention.

[0028] In the present invention, it is preferable that the synthetic resin contains at least one of polyester resin and polyamide resin. Therefore, for example, polyethylene terephthalate, nylon 6, nylon 66, etc. can be preferably used. Any of these known or commercially available products can be used.

[0029] The resin film may be a film containing the above-mentioned resin component as a main component (particularly usually 50% by weight or more, preferably 80% by weight or more, more preferably 95 to 99% by weight), but may contain other components (fillers, colorants, antistatic agents, ultraviolet absorbers, oxygen absorbers, etc.) within the range that does not impair 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.

[0030] 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.

[0031] 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 is desirable in terms of adding higher value, since it can improve, for example, antibacterial properties, gas barrier properties, oxygen and moisture absorbency, etc.

[0032] 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. can be laminated, or various films can be appropriately laminated, on the surface opposite to the surface of the resin film that contacts the contents (i.e., the surface that is exposed to the outside when sealed into a bag).

[0033] 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, 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.

[0034] 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 the components of the laminating adhesive include polyester adhesives, polyether adhesives, and polyurethane adhesives.

[0035] 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 obtained by laminating two or more polyethylene terephthalate films via a polyurethane-based laminate adhesive layer 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.

[0036] base layer 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, thereby achieving higher non-adhesion properties.

[0037] The underlayer has a) an average height of 30 μm or more, b) the interval between adjacent irregularities is 250 μm or less, and c) the number of protrusions constituting the irregularities is 1.5 × 10 7 ~5.5×10 7 pieces / m 2 The embossed structure is

[0038] The average height of the above a) is usually 30 μm or more, and preferably 30 to 100 μm. The method of measuring the average height is to expose 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 at 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 one point x 5 can be regarded as the "average height".

[0039] The interval between adjacent irregularities in the above b) is 250 μm or less, and preferably 1 to 250 μm. The irregularity interval is measured by observing the produced film with a microscope, observing 10 vertices of convexities arbitrarily selected within one field of view, and measuring the distance between each vertex and the vertex of the most distant convexity. The arithmetic average value of these values ​​can be regarded as the "irregularity interval."

[0040] The number of convex portions constituting the concave-convex portions of the above c) is 1.5×10 7 ~5.5×10 7 pieces / m 2 and preferably 1.8×10 7 ~5.2×10 7 pieces / m 2 The method for measuring the number of protrusions is to observe the film with a microscope, measure the length of the diagonal (vertical a, horizontal b) of one protrusion selected arbitrarily in the field of view in a plan view, and calculate the area of ​​one protrusion by regarding the protrusion as a square prism (a × b) per 1 m 2 The number of winning protrusions can be calculated.

[0041] By providing an embossed structure that satisfies all of the above conditions a) to c), it is possible to reliably achieve not only high heat sealability but also highly durable adhesion prevention effects (for example, water repellency).

[0042] The resin component contained in the undercoat layer may be an adhesive containing a known adhesive resin component, etc. 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 may be used.

[0043] 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, vinyl resins, etc. More specifically, examples include a) polyolefin resins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear (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 pentaerythritol, polybutene copolymer, polyethylene, or 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 thereof, copolymers containing combinations of monomers constituting these, modified resins, and the like.

[0044] The content of the adhesive resin component in the undercoat layer may be appropriately set depending on the type of adhesive resin component used, and may be, for example, about 60 to 97% by weight, but is not limited thereto, and may be set to about 70 to 90% by weight.

[0045] Also, a sealant film made of the above adhesive resin component may be attached via the adhesive layer shown in the "base layer" above.

[0046] As a method for forming fine irregularities on the surface of the underlayer, embossing can be suitably adopted, although it is not limited thereto. Examples of the embossing method include the following methods. For example, there are a) a method in which, when extruding the sealant layer resin, the film is pressed and cooled using a cooling roll with an embossed engraving on its surface to form an embossment, b) a method in which, after forming the underlayer, the film is pressed and molded using a roll with an embossed engraving on its surface while heating, and then cooled, and c) a method in which the film of the underlayer alone is embossed and then bonded.

[0047] The embossing pattern is not particularly limited as long as the desired unevenness is formed, and various patterns such as stripes, lattices, and dots can be adopted.

[0048] 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 for contents with high moisture and viscosity. Specifically, when the contents to be put into a bag made of the material of the present invention are foods with low fat content and high moisture content, it is sufficient to coat the surface of the base layer with hydrophobic fine particles.

[0049] 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.

[0050] The hydrophobic fine particles are not particularly limited, but at least one of particles (powders) of silicon oxide, titanium oxide, aluminum oxide, zinc oxide, etc. can be suitably used. More preferably, silicon oxide particles are used. These particles preferably have an average primary particle size of 5 to 50 nm, more preferably 7 to 30 nm.

[0051] The hydrophobic fine particles preferably form a porous layer having a three-dimensional network structure, and the thickness thereof 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.

[0052] The average primary particle diameter of the hydrophobic fine particles 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 average value.

[0053] The content of the 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.

[0054] The method for forming the functional layer is not particularly limited, but can be suitably 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 the whole surface of the undercoat layer and drying it. In order to form the functional layer homogeneously, it is preferable to disperse aggregates in the coating liquid before coating.

[0055] The solvent used in the coating liquid is not particularly limited, and one or more solvents used in food production, such as water and ethanol, can be used.

[0056] The content of the hydrophobic fine particles in the coating liquid is not particularly limited, but it is generally preferable to set it appropriately within the range of about 2 to 200 g / L (liter).

[0057] The method of 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. 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 seal portion so that the functional layer is not formed on the seal portion.

[0058] The coating amount (weight after drying) can be appropriately set according to the desired water repellency, but is usually 0.4 to 1.5 g / m 2 Approximately 0.6 to 1.0 g / m 2 By setting the content within the above range, a porous layer made of anti-adhesion particles can be more reliably formed, and as a result, more excellent non-adhesion properties can be obtained for a long period of time, and further advantages are obtained in terms of preventing the fine particles from falling off, costs, etc.

[0059] After coating, the coated surface is dried to obtain a film in which the adhesion-preventing particles are adhered to the resin-based substrate film. The drying method is not particularly limited, and may be either natural drying or heat drying. When heat drying is performed, it is usually 60 to 190°C, particularly 80 to 150°C. The heating time may be appropriately set depending on the heating temperature, etc., but is usually about 3 to 30 seconds.

[0060] The water repellency of the coated surface is preferably such that the contact angle with pure water (25° C.) is generally 140° or more, and particularly 150° or more.

[0061] 2. Manufacturing method of packaging materials The material of the present invention can be produced by forming each layer and laminating them as explained above in "1. Packaging material".

[0062] Each layer may be formed by appropriately employing, for example, a method of laminating preformed films or a method of applying a coating liquid.

[0063] The lamination of each layer is not limited, and any of the following methods can be appropriately used, for example: bonding via an adhesive layer, lamination by co-extrusion molding, coating each layer with a coating liquid, etc. These methods can also be used in combination.

[0064] 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 when packaging is carried out so that the packaged item is in contact with the functional layer.

[0065] The form of packaging is not limited, and may be any of a form used as a packaging sheet, a form formed into a container, a form made into a bag, etc. In these cases, it is preferable to design the functional layer so that the functional layer is disposed on the inner surface of the container, bag, etc. so that the packaged item is in contact with the functional layer.

[0066] 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 (palm-shaped bag), a gusset bag, a bottom gusset bag, a pouch (standing pouch) bag, a stand-up zipper bag, a side-sealed bag, a bottom-sealed bag, or the like.

[0067] FIG. 2 shows an example of making a three-sided bag using the material of the present invention. FIG. 2A is a plan view, and FIG. 2B is a side view. Two rectangular sheets of the material of the present invention 10, 10 shown in FIG. 2A and FIG. 2B are prepared. Next, as shown in FIG. 2C, they are stacked so that their functional layers face each other. In this state, the heat-sealed areas S are bonded by thermocompression bonding at a predetermined heat-sealed 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.

[0068] As a result, a three-sided bag with a heat-sealed area S bonded can be produced, 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.

[0069] The functional layer on the heat-sealed region S is buried in the base layer during heat sealing, but the functional layer in other regions is left exposed. Therefore, the inner surface of the spatial region a of the bag body 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, the contents are repelled by the functional layer 12 when they are removed, and almost all of them can be removed.

[0070] In the present invention, the term "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, a small amount of gas or the like is allowed to enter and exit the package.

[0071] The packaged items are not particularly limited, and the bag can be used to package foods, chemicals, medicines, cosmetics, etc. In particular, the bag can be used to package liquid items that require anti-adhesion properties. For example, the bag can be used as a bag for storing liquid seasonings such as soy sauce, sauces, dressings, and sauces. EXAMPLES

[0072] The features of the present invention will be described in more detail below with reference to examples and comparative examples, although the scope of the present invention is not limited to the examples.

[0073] Example 1 (1) Preparation of intermediate layer / underlayer A film to be coated 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 base layer on the LLDPE in a sheet form to form a film, while being pressed and cooled by 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 / base layer LLDPE 85 μm" (unevenness height 30 μm, unevenness apex interval (film flow direction) 130 μm, unevenness apex interval (film width direction) 150 μm) was prepared. (2) Formation of functional layer A water-repellent coating liquid was prepared by adding 7 g of commercially available hydrophobic silica particles (average primary particle size: 7 nm) as hydrophobic oxide fine particles to 93 g of ethanol and stirring at room temperature for 30 minutes. This coating liquid was applied to the surface of the underlayer of the laminate, with a weight of 0.6 g / m2 after drying. 2 The mixture was then heated and dried in an oven at 160° C. for 10 seconds (3 m / min) to evaporate the ethanol, forming a functional layer and obtaining a packaging material (strip having a width of 150 mm). (3) Filling and bag making process The packaging material was used to make bags while continuously filling 10 g of commercially available soy sauce (Kikkoman Foods' dark soy sauce) with a liquid / viscous 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, then folded in the longitudinal direction again to form a cylinder with a vertical seal, and soy sauce was poured into the cylinder one by one from a nozzle while horizontal seals were applied while pinching the soy sauce, thus sealing three sides as shown in Fig. 4 to produce a connected body 40 of soy sauce in a bag (a sample 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 soy sauce 44, which is the content, is filled within the seals. The vertical seal conditions were a temperature of 135°C and a pressure of 80kPa left / 50kPa right. The horizontal seal conditions were a temperature of 132°C and a pressure of 380kPa left / 340kPa right. The seal width was 8mm for the vertical seal and 13mm for the horizontal seal. The molded bag size was 47mm long x 75mm wide (including seal width) with a three-sided seal, and the filling speed was 5m / min (bag making capacity 108 bags / min). The seal width was 8mm for the vertical seal and 13mm for the horizontal seal.

[0074] 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.

[0075] 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.

[0076] 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, they were pressed and cooled using a smooth cooling roll.

[0077] 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.

[0078] 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 underlayer surface had a concavo-convex height of 20 μm.

[0079] 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.

[0080] Comparative Example 5 In the above (2) formation of the functional layer, the functional layer has a weight of 2.0 g / m after drying. 2 A bag sample was obtained in the same manner as in Example 1, except that the coating was performed so that the following was true:

[0081] Comparative Example 6 In the above (2) formation of the functional layer, the functional layer has a weight of 0.3 g / m after drying. 2 A bag sample was obtained in the same manner as in Example 1, except that the coating was performed so that the following was true:

[0082] 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.

[0083] (1) Initial water repellency Using a micropipette (pipetman P20, manufactured by Gilson) equipped with a micropipette tip (Ibis pipette tip, manufactured by Ibis), Kikkoman Foods' dark soy sauce was gently dropped onto the surface of the sample before it was made into a bag. Samples that slid down smoothly when tilted were rated as "good", and samples where even a part of the sample was stuck were rated as "bad".

[0084] (2) Water repellency retention The 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 (10Hz-10 seconds, 15Hz-10 seconds, 20Hz-10 seconds, 25Hz-10 seconds, and 30Hz-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 attached to the inner surface of the bag sample (adhered area) 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 ​​less than 10 to 30% were marked with "○", and samples with an adhesion area of ​​30 to 100% were marked with "×".

[0085] (3) Transportation Test The 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 (10Hz-10 seconds, 15Hz-10 seconds, 20Hz-10 seconds, 25Hz-10 seconds, and 30Hz-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 attached to the inner surface of the bag samples (adhered area) 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 ​​less than 10 to 30% were marked as "△", and samples with an adhesion area of ​​30 to 100% were marked as "X".

[0086] (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 "×".

[0087] [Table 1]

[0088] 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

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 a) an average height of 30 μm or more, b) an interval between adjacent irregularities is 250 μm or less, and c) the number of protrusions constituting the irregularities is 1.5×10 ７ ~5.5 x 10 ７ pieces / m ２ The embossed structure is (2) The functional layer contains hydrophobic fine particles having a primary average particle size of 5 to 50 nm at a dry weight of 0.4 to 1.5 g / m ２ Including, (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 by:

2. A packaging material as described in claim 1, having an area on the base layer where a functional layer is formed and an area where the functional layer is not formed, and in the area where the functional layer is not formed, the surface of the base layer is exposed to the outside.

3. 3. A bag according to claim 1 or 2, wherein the base layers of the packaging material are thermally bonded together.

Images