Sealant film and laminate film

Abstract

To provide a sealant film and a laminate film with excellent ease of handling while also containing a recycled material.SOLUTION: A sealant film 10 includes a recycled material using, as a raw material, a laminate in which a plurality of resin layers consisting solely of polyethylene resin films are laminated via an adhesive layer, the sealant film 10 having a multilayer structure of at least two layers, and having, on at least one of end faces 14 and 15 in the thickness direction, a virgin resin layer that does not contain the recycled material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sealant film and a laminated film.

Background Art

[0002] Patent Document 1 describes a manufacturing method in which a synthetic resin containing aluminum foil pieces is supplied to an extruder, kneaded while crushing the aluminum foil to granulate pellets, and then the pellets taken out from cooling water are dehydrated and dried to a water content of 0.1% or less. Patent Document 2 describes a laminated film in which a recycled polyethylene layer is laminated with a linear low-density polyethylene layer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Paragraph 0036 of Patent Document 1 describes manufacturing various molded products such as blocks, bricks, piles, fences, building materials, sheets, injection molded products, and multilayer containers from recycled pellets, but does not describe using them for sealant films such as packaging bags. Paragraph 0044 of Patent Document 2 describes having a linear low-density polyethylene layer not containing recycled polyethylene as the innermost layer, and paragraph 0086 describes manufacturing synthetic resin products such as packages using a laminated film having a recycled polyethylene layer, but does not describe using them for sealant films such as packaging bags.

[0005] The sealant film is laminated with other resin films such as a base film to be used in the manufacture of packaging bags and the like. Before being laminated with other resin films, the sealant film is handled as a single film. Therefore, in order to use a laminated film having a recycled polyethylene layer as a sealant film, further improvement is required. When performing horizontal recycling from one packaging bag to another, it is difficult to remove impurities such as adhesives, inks, and additives. Even if these are mixed in, improvement is required to achieve a strength that allows use as a sealant film.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a sealant film and a laminated film that contain a recycled material and are excellent in handleability.

Means for Solving the Problems

[0007] A first aspect is a sealant film containing a recycled material using a laminate in which a plurality of resin layers composed only of a polyethylene-based resin film are laminated via an adhesive layer as a raw material, wherein the sealant film has a multilayer structure of at least two or more layers, and a virgin resin layer not containing the recycled material is provided on at least one end face in the thickness direction.

[0008] A second aspect is, in the first aspect, that the sealant film has virgin resin layers not containing the recycled material on both end faces in the thickness direction. A third aspect is, in the first or second aspect, that the density of the virgin resin contained in the sealant film is 0.910 g / cm 3 or more and 0.930 g / cm 3 or less. A fourth aspect is, in any one of the first to third aspects, that the content ratio of the recycled material in the sealant film is 50% by weight or less.

[0009] A fifth aspect is, in any one of the first to fourth aspects, that the recycled material contains high-density polyethylene. The sixth aspect is that, in any one of the first to fifth aspects, the recycled material contains a printing ink component or a urethane-based adhesive. The seventh aspect is that, in any one of the first to sixth aspects, the total light transmittance of the sealant film is 65 to 90%. The eighth aspect is a laminated film in which a base film is laminated on the sealant film according to any one of the first to seventh aspects.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide a sealant film and a laminated film that contain a recycled material and have excellent handleability.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described based on preferred embodiments.

[0013] As shown in FIG. 1, the sealant film 10 of the embodiment has a multilayer structure of at least two or more layers. As a manufacturing method of the multilayer structure, multilayer inflation molding, multilayer T-die molding, dry lamination, extrusion lamination, etc. can be used.

[0014] The multilayer structure in the illustrated example includes end layers 11 and 13 that face the end faces in both the thickness directions, and an intermediate layer 12 laminated between the end layers 11 and 13. The multilayer structure of at least two or more layers may be a two-layer multilayer structure composed of the end layers 11 and 13, or a three-layer or more multilayer structure including one or two or more intermediate layers 12.

[0015] The sealant film 10 contains a recycled material using a polyethylene-based resin film as a raw material, except for at least one-sided end layers 11, 13.

[0016] The recycled material is manufactured using, for example, as shown in FIG. 2, a laminate 20 in which a plurality of resin layers 21, 22, 23 consisting only of a polyethylene-based resin film are laminated via adhesive layers 24, 25 as a raw material. The number of resin layers 21, 22, 23 is not particularly limited, and is not limited to the three layers in the illustrated example, and may be two layers or four or more layers.

[0017] At least one-sided end layers 11, 13 are virgin resin layers that do not contain the recycled material. As a result, since at least one-sided end faces 14, 15 are formed from virgin resin layers, it becomes easy to manage the hygiene of the surface that comes into contact with the contents, and also the sealing property when heat-welding the sealant films 10 together can be improved. It is preferable that both end layers 11, 13 are virgin resin layers and both end faces 14, 15 do not contain the recycled material.

[0018] Examples of the polyethylene-based resin include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), etc. The polyethylene-based resin may be a homopolymer of ethylene or a copolymer mainly composed of ethylene.

[0019] Examples of monomers (comonomers) other than ethylene include one or more of α-olefins such as 1-butene, 1-hexene, 1-octene, cyclic olefins such as norbornene, and vinyl-based monomers such as vinyl acetate, vinyl chloride, and acrylic acid. When the polyethylene-based resin copolymerizes a monomer having an ester group such as vinyl acetate, a part of the ester group may be saponified to form a copolymer containing vinyl alcohol.

[0020] The proportion of ethylene in the constituent monomers of the polyethylene-based resin is preferably 50% by weight or more, and may be, for example, 80 to 100% by weight. Ethylene or comonomers may be compounds derived from fossil resources such as petroleum, compounds derived from biomass such as plants, or compounds obtained by chemical recycling. Chemical recycling refers to a process of generating compounds such as monomers by chemical treatment of the raw materials of recycled materials.

[0021] The resin contained in the polyethylene-based resin layer may be only the polyethylene-based resin, or may contain other resins. It is preferable that the polyethylene-based resin layer is composed of 80% by weight or more, 90% by weight or more, or 95% by weight or more of the polyethylene-based resin. Each polyethylene-based resin layer may be composed of one type of polyethylene-based resin, or may be composed of two or more types of polyethylene-based resins.

[0022] The polyethylene-based resin may contain additives other than the resin. The additives are not particularly limited, and examples include antioxidants, lubricants, antiblocking agents, flame retardants, ultraviolet absorbers, light stabilizers, antistatic agents, colorants, crosslinking agents, and the like. The additives may be components compatible with the resin or components incompatible with the resin.

[0023] The virgin resin layer is a polyethylene-based resin layer made of virgin polyethylene-based resin. Virgin polyethylene-based resin refers to resin that is industrially polymerized from monomers and used in products for the first time, and may be simply referred to as "virgin resin" in the following description. Virgin resin can contain monomers obtained by the above-mentioned chemical recycling.

[0024] The composition, degree of polymerization, density, melting point, etc. of virgin resin can be easily controlled so as to have desired physical properties. Therefore, virgin resin can be used stably, but compared with recycled materials, it has a greater environmental impact in the processes of monomer production, polymerization, etc.

[0025] In the raw materials of the recycled material, the resin layers 21, 22, and 23 are polyethylene resin layers made of polyethylene resin. The polyethylene resin of the recycled material refers to a resin that is industrially polymerized from monomers, then recovered after being used in products or without being used in products, and reused without being returned to monomers through processes such as crushing and melting. In the following description, it may simply be referred to as the "recycled material".

[0026] Examples of products using polyethylene resin include films, sheets, packaging bags, molded products, etc. Scrap materials such as edges of films and sheets, used packaging films and packaging bags are used as raw materials for the recycled material. It is also possible to use only a laminate in which a plurality of resin layers composed only of polyethylene resin films are laminated via an adhesive layer as the raw material of the recycled material, and other raw materials may be used in part. Examples of the ratio of other raw materials include 20% by weight or less, 10% by weight or less, etc.

[0027] The recycled material undergoes a heat history due to product processing before recycling, etc., and also undergoes a heat history again in processes such as recovery, crushing and melting, and product processing after recycling. Also, in the history before and after recycling, the recycled material is loaded from mechanical, optical, chemical, etc. viewpoints. For this reason, even when the recycled material is processed from raw materials with relatively uniform properties such as scrap materials and unused waste materials, its performance may be inferior to that of virgin resin.

[0028] Furthermore, in the recycled material, it may be processed in a state where various raw materials are mixed during recycling. For example, polyethylene resins with different compositions, degrees of polymerization, densities, melting points, etc. may not be sufficiently separated, and / or foreign substances such as additives, impurities, and adherends may not be sufficiently removed before processing. For this reason, it may be difficult to obtain stable performance, or foreign substances may affect the performance of the resin.

[0029] Depending on the use of the recycled material, it is possible to select raw materials. However, when the raw material is a composite material, it may be difficult to select and separate. For example, the polyethylene-based resin film of the raw material may include a laminate containing resins with relatively low density such as LDPE and LLDPE and resins with relatively high density such as HDPE and MDPE.

[0030] As described above, when the laminate 20 in which a plurality of resin layers 21, 22, 23 composed only of the polyethylene-based resin film are laminated via the adhesive layers 24, 25 is used as the raw material, even if the resin layers 21, 22, 23 are different types of polyethylene-based resin layers, it is difficult to peel the adhesive layers 24, 25 or separate the resin layers 21, 22, 23. Therefore, it is not easy to adjust the quality of the recycled material.

[0031] The density of the virgin resin contained in the sealant film 10 is preferably 0.910 g / cm 3 or more and 0.930 g / cm 3 or less. Thereby, the processability of the recycled material can be improved. If the density of the virgin resin is too low, there is a risk of easy blocking. As the virgin resin used for the sealant film 10, resins with relatively low density such as LDPE and LLDPE are preferable.

[0032] The content ratio of the recycled material in the sealant film 10 is preferably 50% by weight or less. By mixing and using a virgin resin having physical properties suitable for the sealant and a recycled material whose quality adjustment is difficult, it is possible to achieve both reduction of environmental load and quality assurance. The content ratio of the recycled material may have at least one selected from 50% by weight, 40% by weight, 30% by weight, 20% by weight, 10% by weight, and 5% by weight as the upper limit or the lower limit.

[0033] From the perspective of quality adjustment of the sealant film 10, it is preferable to use a recycled material having physical properties suitable for sealants such as LDPE and LLDPE. However, the raw materials of the recycled material are limited to end materials of the sealant material, etc., and it may be difficult to secure a sufficient quantity. For this reason, it is preferable that the recycled material contains HDPE.

[0034] Since HDPE is suitable as a base film of a polyethylene-based resin film, as the laminate 20 of raw materials, a composite film including a base film and a sealant film can be used.

[0035] From the perspective of quality adjustment of the sealant film 10, it is preferable to sufficiently remove foreign materials such as printing ink components and urethane-based adhesives. However, the treatment of the recycled material becomes complicated and the price may increase. For this reason, it is preferable that the recycled material contains a printing ink component or a urethane-based adhesive. The recycled material containing a printing ink component may be a material having a lower total light transmittance than the virgin material. For example, the total light transmittance of the sealant film 10 may be 90% or less. However, compared with a sealant film made only of recycled material, by having a virgin resin layer that does not contain the recycled material, the total light transmittance can be made relatively high. For example, the total light transmittance of the sealant film 10 may be 65% or more. In addition, the sealant film containing the recycled material is excellent in light shielding properties and concealment properties because its total light transmittance is lower than that of a sealant film made only of virgin material.

[0036] The printing ink component is useful for securing a display surface and improving designability when commercializing a polyethylene-based resin film, and the urethane-based adhesive is useful for adhesion between the resin layers 21, 22, 23. For this reason, as the laminate 20 of raw materials, a composite film including a printing layer (not shown) and adhesive layers 24, 25 can be used.

[0037] The sealant film 10 can be used to produce a laminated film 16 by laminating it with a base film 17. Since the sealant film 10 occupies a large proportion in the laminated film 16, increasing the recycling rate of the sealant film 10 is advantageous for increasing the recycling rate of the laminated film 16.

[0038] The base film 17 is not particularly limited, and examples thereof include polyolefin resins such as polyethylene (PE) and polypropylene (PP), polyester resins such as polyethylene terephthalate (PET), and polyamide resins such as nylon (Ny). The base film 17 may be a single layer or two or more layers. Considering subsequent recycling, the base film 17 is preferably a PE-based resin.

[0039] Although not particularly shown, the laminated film 16 may have at least one selected from a printed layer, an adhesive layer, a barrier resin layer such as ethylene-vinyl alcohol copolymer (EVOH), a metal vapor deposition layer such as aluminum, a metal foil such as aluminum foil, an inorganic vapor deposition layer such as silica or alumina, and an extruded resin layer such as PE. The sealant film 10 and the base film 17 may be adhered with a urethane-based adhesive.

[0040] The laminated film 16 may be used for manufacturing packaging containers such as packaging bags. Specific examples of the packaging bag include three-side seal bags, four-side seal bags, pillow bags, gusset bags, standing pouches, etc.

[0041] The dimensions of the packaging bag are not particularly limited. For example, in the case of a refill container, the height in the vertical direction is about 100 to 500 mm, the width in the horizontal direction is about 70 to 300 mm, and the filling volume is 100 cm 3 ~5000 cm 3 or so.

[0042] The packaging bag can obtain a desired packaged product (packaging bag containing contents) by being sealed in a state filled with a predetermined content. The state of the content is not particularly limited, and examples include fluids such as liquids, powders, and granules, or solids such as articles. The type of the content is not particularly limited, and examples include detergents, drugs, cosmetics, pharmaceuticals, beverages, seasonings, inks, paints, fuels, and the like.

[0043] As described above, the present invention has been described based on preferred embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention. Examples of the modifications include addition, substitution, omission, and other changes of components.

Example

[0044] Hereinafter, the present invention will be specifically described with reference to examples.

[0045] A sealant film 10 having three layers of an outer (end layer 13), a middle (intermediate layer 12), and an inner (end layer 11) was manufactured by multi-layer inflation according to the layer configuration and layer ratio shown in Table 1. The layer ratio is a relative weight ratio determined according to the product of the thickness and density of each layer. The recycling rate is the weight ratio (weight %) of the recycled material used for each layer. "R" in the layer configuration represents a layer having a recycling rate greater than 0 wt%, and "V" represents a virgin resin layer having a recycling rate of 0 wt%.

[0046] As the recycled material, a laminate in which an HDPE layer and an LLDPE layer are laminated via a printed ink layer and a urethane-based adhesive layer was used as a raw material, and a polyethylene-based resin obtained by pelletizing was used.

[0047] As the virgin resin, C6LLDPE copolymerized with a comonomer having 6 carbon atoms was used. The density of the virgin resin is as shown in Table 1.

[0048]

Table 1

[0049] The evaluation results of the sealant film are shown in Table 2. The evaluation method is as follows.

[0050] (Recycling rate) The recycling rate of the entire sealant film was calculated by the following formula using the layer ratios (A 外 , A 中 , A 内 ) and recycling rates (B 外 , B 中 , B 内 ) of each layer of the sealant film. "Overall recycling rate" = (A 外 B 外 + A 中 B 中 + A 内 B 内 ) / (A 外 + A 中 + A 内 )

[0051] (Processability) Processability was evaluated according to the following criteria for film-forming property and blocking, respectively. For film-forming property, when the bubbles were stable, it was marked as "○", when there was some disturbance in the bubbles but they were still stable, it was marked as "△", and when the bubbles were not stable, it was marked as "×". For blocking, when there was no adhesion on the inner surface of the tube, it was marked as "○", when there was some adhesion on the inner surface of the tube but it could be easily peeled off, it was marked as "△", and when there was adhesion on the inner surface of the tube and it could not be easily peeled off, it was marked as "×".

[0052] (Dart impact test) The dart impact test was carried out in accordance with JIS K7124-1 staircase A method. For the sealant film, darts were dropped from a predetermined height of 0.66 m, and the impact failure mass (g) was measured. When the impact failure mass was 1200 g or more, it was recorded as 1200 or more.

[0053] (Gelbo flex test) The Gelboflex test was evaluated by measuring the number of pinholes generated after bending the sealant film 500 or 1000 times using a Tester Industry-made BE-1005 Gelboflex tester. The "-" in Table 2 represents unmeasured values.

[0054] (Total light transmittance) The measurement of the total light transmittance was carried out in accordance with JIS K7361. It was measured using a NDH4000 made by Nippon Denshoku Industries Co., Ltd.

[0055]

Table 2

[0056] As shown in Table 2, at least good results were obtained for the sealant films of Examples 1 to 8. Furthermore, excellent results were obtained for the sealant films of Examples 4 to 8. From this, it can be seen that according to the present invention, the film-forming property and the bending resistance are improved.

Explanation of reference numerals

[0057] 10…Sealant film, 11, 13…Terminal layer, 12…Intermediate layer, 14, 15…Terminal surface, 16…Laminated film, 17…Base material film, 20…Laminated body, 21, 22, 23…Resin layer, 24, 25…Adhesive layer.

Claims

1. A sealant film containing a recycled material using, as a raw material, a laminate in which a plurality of resin layers composed only of a polyethylene-based resin film are laminated via an adhesive layer, wherein the sealant film has a multilayer structure of at least two or more layers, and has a virgin resin layer not containing the recycled material on at least one end face in the thickness direction. A sealant film characterized by this.

2. The sealant film according to Claim 1, characterized by having a virgin resin layer not containing the recycled material on both end faces in the thickness direction of the sealant film.

3. The density of the virgin resin contained in the sealant film is 0.910 g / cm ３ or more and 0.930 g / cm ３ or less, and the sealant film according to claim 1 or 2, characterized in that.

4. The sealant film according to Claim 1 or 2, characterized in that the content ratio of the recycled material in the sealant film is 50% by weight or less.

5. The sealant film according to Claim 1 or 2, characterized in that the recycled material contains high-density polyethylene.

6. The sealant film according to Claim 1 or 2, characterized in that the recycled material contains a printing ink component or a urethane-based adhesive.

7. The sealant film according to Claim 1 or 2, characterized in that the total light transmittance of the sealant film is 65 to 90%.

8. A laminated film in which a base film is laminated on the sealant film according to Claim 1 or 2.

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