Laminate, laminate manufacturing method, container, material for container, and container manufacturing method

Abstract

To provide a laminate which enables a resin layer to be easily peeled from a paper layer, can prevent breakage of the resin layer when being peeled, and can prevent a part of the resin layer from remaining on the paper layer after having been peeled, a laminate manufacturing method, a container, a material for a container, and a container manufacturing method.SOLUTION: There is provided a laminate in which a paper layer and a polyester layer are stacked, wherein thickness of the polyester layer is 10 to 20 μm, and peeling strength when the polyester layer is peeled from the paper layer is 0.7 to 1.3 N / 25 mm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate, a method for manufacturing a laminate, a container, a material for a container, and a method for manufacturing a container. Specifically, the present invention relates to a laminate, a method for manufacturing a laminate, a container, a material for a container, and a method for manufacturing a container, which enable a resin layer to be easily peeled from a paper layer, prevent breakage of the resin layer during peeling, and prevent part of the resin layer from remaining on the paper layer after peeling. [Background technology]

[0002] Conventionally, in technologies for using a laminate of a paper layer and a resin layer in a container, attempts have been made to improve the adhesion between these layers in order to prevent peeling at the interface between the paper layer and the resin layer (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-138381 Summary of the Invention [Problem to be solved by the invention]

[0004] From the viewpoint of environmental compatibility, the present inventors have investigated how to make it possible to separate and dispose of the paper layer and the resin layer in a laminate of a paper layer and a resin layer. Conventional techniques such as those described in Patent Document 1 are intended to improve the adhesiveness between the paper layer and the resin layer, and therefore do not meet such demands. In order to achieve suitable separate disposal, it is desirable that the resin layer can be easily peeled from the paper layer, that the resin layer can be prevented from breaking during peeling, and that part of the resin layer can be prevented from remaining on the paper layer after peeling.

[0005] One object of the present invention is to provide a laminate, a method for manufacturing a laminate, a container, a material for a container, and a method for manufacturing a container, which enable a resin layer to be easily peeled from a paper layer, prevent breakage of the resin layer during peeling, and prevent part of the resin layer from remaining on the paper layer after peeling. [Means for solving the problem]

[0006] As a result of extensive research, the inventors have discovered that by laminating a polyester layer as a resin layer on a paper layer and providing the polyester layer with a specific thickness and specific peel strength, the resin layer can be easily peeled from the paper layer, breakage of the resin layer during peeling can be prevented, and part of the resin layer can be prevented from remaining on the paper layer after peeling, thereby completing the present invention. According to the present invention, the following laminate and the like can be provided. 1. A paper layer and a polyester layer are laminated together. The thickness of the polyester layer is 10 to 20 μm, The laminate has a peel strength of 0.7 to 1.3 N / 25 mm when the polyester layer is peeled from the paper layer. 2. The laminate according to 1, wherein the paper layer and the polyester layer are directly laminated together. 3. The laminate according to 1 or 2, wherein the paper layer is kraft paper or recycled paper. 4. The laminate according to 1 or 2, wherein a core and a liner are laminated in this order on the surface of the paper layer opposite the polyester layer. 5. Including laminating a polyester layer to a paper layer; The thickness of the polyester layer is 10 to 20 μm, The method for producing a laminate, wherein the resulting laminate has a peel strength of 0.7 to 1.3 N / 25 mm when the polyester layer is peeled from the paper layer. 6. The method for producing a laminate according to 5, wherein the polyester layer is directly laminated onto the paper layer. 7. The method for producing a laminate according to 5 or 6, further comprising subjecting the paper layer to a corona discharge treatment before laminating the polyester layer onto the paper layer, and adjusting the output of the corona discharge treatment so that the peel strength is 0.7 to 1.3 N / 25 mm. 8. A container comprising the laminate according to any one of 1 to 4. 9. A container material comprising the laminate according to any one of 1 to 4. 10. A method for manufacturing a container, which uses the laminate according to any one of 1 to 4, or includes the method for manufacturing the laminate according to any one of 5 to 7. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a laminate, a method for manufacturing a laminate, a container, a material for a container, and a method for manufacturing a container, which allow a resin layer to be easily peeled from a paper layer, prevent breakage of the resin layer during peeling, and prevent part of the resin layer from remaining on the paper layer after peeling. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of a laminate according to one embodiment of the present invention. [Figure 2] 10A and 10B are diagrams illustrating another example of a laminate according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The laminate, the method for producing the laminate, the container, the material for the container, and the method for producing the container of the present invention will be described in detail below. In this specification, "x to y" represents a numerical range of "not less than x and not more than y." The upper and lower limits of the numerical ranges can be combined in any way.

[0010] 1.Laminate FIG. 1 is a cross-sectional view showing an example of a laminate according to one embodiment of the present invention. The laminate shown in Figure 1 includes a paper layer 1 and a polyester layer 2 laminated on the paper layer 1, the polyester layer 2 having a thickness of 10 to 20 μm, and a peel strength of 0.7 to 1.3 N / 25 mm when peeling the polyester layer 2 from the paper layer 1.

[0011] In the laminate of this embodiment, the paper layer 1 and the polyester layer 2 are integrally formed, but the polyester layer 2 can be easily peeled from the paper layer 1, preventing breakage of the polyester layer 2 during peeling, and preventing any part of the polyester layer 2 from remaining on the paper layer 1 after peeling. Therefore, after use of the laminate, the paper layer 1 and the polyester layer 2 can be easily separated and disposed of separately. In particular, the paper layer 1 can be easily recycled. From one point of view, the laminate of this embodiment can also be said to be a laminate in which the polyester layer 2 can be peeled from the paper layer 1. In the laminate, the polyester layer 2 can be peeled from the paper layer 1 by pinching one end with the fingers.

[0012] (Paper layer 1) The paper constituting the paper layer 1 is not particularly limited, and examples thereof include kraft paper, semi-bleached kraft paper, bleached kraft paper, recycled paper, fine paper, pure white roll paper, liner paper, core raw paper, white cardboard, etc. Kraft paper is particularly preferred from the viewpoint of suppressing flexure of the paper layer 1 and further improving the releasability of the polyester layer 2. Recycled paper is also preferred from the viewpoint of environmental compatibility. The basis weight of the paper layer 1 can be appropriately set depending on the application of the laminate, for example, 30 to 500 g / m 2 It could be.

[0013] (Polyester layer 2) The polyester layer 2 is a layer containing polyester. The polyester content in the polyester layer 2 can be, for example, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more. Examples of polyesters include polyethylene terephthalate (abbreviated as "PET"), polybutylene terephthalate (abbreviated as "PBT"), glycol-modified polyethylene terephthalate (abbreviated as "PET-G"), etc. As the polyester contained in the polyester layer 2, one type may be used alone, or two or more types may be used in combination. As the PET, for example, one having an intrinsic viscosity of 0.55 to 0.95 dl / g can be suitably used. As PBT, for example, one having an intrinsic viscosity of 0.65 to 1.15 dl / g can be suitably used. The intrinsic viscosity is a value measured by a method using a capillary viscometer. The polyester layer 2 may contain components other than polyester, such as antioxidants, surfactants, slip agents, antiblocking agents, colorants such as pigments, crystallization accelerators, and crystallization retarders. The thickness of the polyester layer 2 is preferably 11 μm or more, and more preferably 13 μm or more, which can more suitably prevent the polyester layer 2 from breaking during peeling. The thickness of the polyester layer 2 is preferably 19 μm or less, and more preferably 17 μm or less, which more preferably prevents part of the polyester layer 2 from remaining on the paper layer 1 after peeling. If the thickness of the polyester layer 2 is less than 10 μm, the polyester layer 2 is likely to break when peeled off. If the thickness of the polyester layer 2 exceeds 20 μm, the polyester layer 2 is less likely to be easily peeled off when peeled off, and the polyester layer 2 is more likely to remain on the paper layer 1.

[0014] It is preferable that the paper layer 1 and the polyester layer 2 are laminated directly. Here, "directly" means that there is no other layer such as an adhesive layer interposed therebetween. In this case, the paper constituting the paper layer 1 is in contact with the polyester layer 2. This allows the polyester layer 2 to be more easily peeled from the paper layer 1. Alternatively, the paper layer 1 may have a surface layer (not shown) on the surface on which the polyester layer 2 is laminated. The surface layer can be formed over part or all of the surface on which the polyester layer is laminated. Examples of the surface layer include a resin layer and a printed layer. The resin layer has a different composition from the polyester layer 2, and the type of resin is not particularly limited and can include, for example, polyethylene, polypropylene, etc. The printed layer can include a coloring material such as a pigment.

[0015] In the laminate, another layer may be laminated on the surface of the paper layer 1 opposite to the polyester layer 2. An example is shown below. Fig. 2 is a cross-sectional view showing another example of a laminate according to an embodiment of the present invention, in which the same reference numerals as in Fig. 1 indicate the same components, and the explanation given for Fig. 1 is incorporated herein. In the laminate shown in Figure 2, the paper layer 1 forms one liner of the corrugated cardboard 5. The corrugated cardboard 5 is integrally formed by laminating one liner (paper layer 1), a corrugated core 3, and the other liner 4 in this order. The core 3 and the liner 4 can each be made of paper. The same explanation as given for the paper layer 1 applies to paper. By including such a corrugated board structure in the laminate, the paper layer 1 is less likely to bend, and the polyester layer 2 can be more stably peeled from the paper layer 1. Furthermore, peeling of the polyester layer 2 from the paper layer 1 can be prevented when forming such a corrugated board structure.

[0016] The peel strength when peeling the polyester layer 2 from the paper layer 1 may be 0.7 to 1.3 N / 25 mm, preferably 0.8 to 1.2 N / 25 mm, and more preferably 0.9 to 1.1 N / 25 mm. If the peel strength is less than 0.7 N / 25 mm, the polyester layer may unintentionally peel off. For example, when forming the above-mentioned corrugated board structure, the polyester layer 2 may easily peel off from the paper layer 1. On the other hand, if the peel strength exceeds 1.3 N / 25 mm, the resin layer may break during peeling, or part of the resin layer may remain on the paper layer after peeling.

[0017] 2. Manufacturing method of laminate A method for producing a laminate according to one embodiment of the present invention includes laminating a polyester layer 2 onto a paper layer 1, wherein the polyester layer 2 has a thickness of 10 to 20 μm, and the resulting laminate has a peel strength of 0.7 to 1.3 N / 25 mm when peeling the polyester layer from the paper layer. According to the manufacturing method of this embodiment, the laminate according to the embodiment of the present invention can be manufactured. From one point of view, the manufacturing method of the laminate of this embodiment can be said to be a method of integrally laminating the paper layer 1 and the polyester layer 2 so that the polyester layer 2 can be peeled from the paper layer 1. In the manufacturing method of this embodiment, the explanation given for the laminate according to one embodiment of the present invention is applicable to the obtained laminate, paper layer 1, polyester layer 2, core 3 and other liner 4.

[0018] As an example of a method for producing a laminate, first, PET resin is placed in an extruder and extruded onto a paper layer 1 at a predetermined extrusion temperature to form a polyester layer 2. Here, the PET resin may be pre-mixed with a chain extender or the like (masterbatch). The extruder is not particularly limited, and a co-rotating twin-screw extruder, for example, can be used. The extrusion temperature can be, for example, 270 to 290°C. The thickness of the polyester layer 2 is controlled to be 10 to 20 μm. The laminate is then cooled with a cooling roll. The temperature of the cooling roll can be set appropriately, and for example, the temperature of the cooling roll in contact with the polyester layer 2 can be 10 to 30°C. In this manner, a laminate can be produced.

[0019] Before laminating the polyester layer on the paper layer, the paper layer is preferably subjected to a corona discharge treatment, and the output of the corona discharge treatment is preferably adjusted so that the peel strength is 0.7 to 1.3 N / 25 mm. The output of the corona discharge treatment can be adjusted appropriately depending on the material of the paper layer, the type of surface layer that constitutes the paper layer, etc., so that the above-mentioned peel strength is achieved. For example, if the paper layer is kraft paper, the output of the corona discharge treatment can be set to 0.5 to 1.5 kW, and if the paper layer is recycled paper, the output of the corona discharge treatment can be set to 2.5 to 3.5 kW.

[0020] Furthermore, after laminating the polyester layer 2 on the paper layer 1, a core 3 and the other liner 4 can be laminated on the side of the paper layer 1 opposite the polyester layer 2, thereby producing a laminate having a cardboard structure as shown in Figure 2. Alternatively, a laminate having a cardboard structure as shown in Figure 2 can be produced by laminating a core 3 and the other liner 4 on one side of the paper layer 1 before laminating the polyester layer 2, and then laminating the polyester layer 2 on the other side of the paper layer 1. As a method for laminating the medium 3 and the other liner 4 onto the paper layer (one liner) 1, a known method for manufacturing corrugated cardboard can be applied without any particular restrictions.

[0021] 3. Container A container according to an aspect of the present invention includes the laminate according to an aspect of the present invention. In such a container, the resin layer can be easily peeled from the paper layer, breakage of the resin layer during peeling can be prevented, and part of the resin layer can be prevented from remaining on the paper layer after peeling.Furthermore, peeling of the polyester layer from the paper layer can be prevented when forming the container. The shape of the container is not particularly limited, and examples thereof include trays, boxes, bags, and the like. For example, the bottom and side walls of a tray can each be made of the laminate of this embodiment. The tray can be one in which the bottom and side walls are formed by folding a single laminate. The tray can also have a lid, which can also be made of the laminate of this embodiment, and the bottom, side walls, and lid can be formed by folding a single laminate. The laminate constituting the container preferably has the polyester layer oriented toward the content (item housed in the container) side, in other words, the inner surface of the container is preferably formed by the polyester layer of the laminate.

[0022] The use of the container is not particularly limited, but it is preferably a food container. There are no particular limitations on the type of food that can be stored in the food container, and examples include pizza, bread, pasta, hamburgers, etc. Even if the food contains moisture or oil, the presence of the polyester layer can prevent these from adhering to the paper layer. For hygiene reasons, it is common to avoid using recycled paper as the paper that makes up paper food containers. However, with the container of this embodiment, the polyester layer in the laminate is oriented toward the food side, thereby preventing contact between the paper layer and the food, so recycled paper can also be suitably used as the paper layer.

[0023] After the contents are removed from the container, the polyester layer can be peeled off from the paper layer of the laminate constituting the container, allowing them to be separated and disposed of. The paper layer in particular can be suitably recycled. A mark indicating that the polyester layer is peelable may be printed on the container.

[0024] 4.Container materials A container material according to one aspect of the present invention includes the laminate according to one aspect of the present invention. In a container obtained using such a container material, the resin layer can be easily peeled from the paper layer, breakage of the resin layer during peeling can be prevented, and part of the resin layer can be prevented from remaining on the paper layer after peeling.Furthermore, peeling of the polyester layer from the paper layer can be prevented during container formation.

[0025] 5. Container manufacturing method A method for manufacturing a container according to an aspect of the present invention uses the laminate according to an aspect of the present invention or includes a method for manufacturing the laminate according to an aspect of the present invention. In the container obtained by this method, the resin layer can be easily peeled from the paper layer, breakage of the resin layer during peeling can be prevented, and part of the resin layer can be prevented from remaining on the paper layer after peeling. Furthermore, peeling of the polyester layer from the paper layer can be prevented during container formation. [Example]

[0026] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0027] 1. Manufacturing of laminates Example 1 98.5 parts by weight of PET resin "S103" (intrinsic viscosity: 0.80 dl / g) manufactured by Riley Co., Ltd. and 1.5 parts by weight of a PET masterbatch containing 10% by weight of chain extender "ADR4468" manufactured by BASF Japan Ltd. were mixed and stirred in a blender. This mixed resin was fed into a single-screw extruder manufactured by Sumitomo Heavy Industries Modern Co., Ltd. (screw shaft diameter: 90 mm) and extruded and laminated onto a paper layer (core base paper) at an extrusion temperature of 300°C. The extrusion was then cooled with a cooling roll (the cooling roll in contact with the polyester layer was passed through a chiller water at 15°C), resulting in a paper layer / polyester layer laminate. The polyester layer was 15 μm thick. The surface of the paper layer where the polyester layer would be laminated was subjected to corona discharge treatment at an output of 3.0 kW prior to extrusion (before laminating the polyester layer).

[0028] Example 2 A paper layer / polyester layer laminate was obtained in the same manner as in Example 1, except that the thickness of the polyester layer was 10 μm.

[0029] Example 3 A paper layer / polyester layer laminate was obtained in the same manner as in Example 1, except that the thickness of the polyester layer was 20 μm.

[0030] (Comparative Example 1) A paper layer / polyester layer laminate was obtained in the same manner as in Example 1, except that the corona discharge treatment was carried out at an output of 2.0 kW.

[0031] (Comparative Example 2) A paper layer / polyester layer laminate was obtained in the same manner as in Example 1, except that the corona discharge treatment was carried out at an output of 4.0 kW.

[0032] (Comparative Example 3) A paper layer / polyester layer laminate was obtained in the same manner as in Example 1, except that the thickness of the polyester layer was 9 μm.

[0033] Comparative Example 4 A paper layer / polyester layer laminate was obtained in the same manner as in Example 1, except that the thickness of the polyester layer was 21 μm.

[0034] 2. Testing and evaluation methods (1) Peel strength measurement For each laminate obtained in the Examples and Comparative Examples, the peel strength was measured when peeling the polyester layer from the paper layer. Specifically, the test piece was 25 mm wide, and the peel strength was measured at a peel rate of 100 mm / min at 180° peeling. The peel strength measurement was performed three times for each test piece, and the average value was used.

[0035] (2) Peel test For each of the laminates obtained in the Examples and Comparative Examples, one end of the polyester layer was pinched with fingers and peeled off from the paper layer, and the appearance was visually observed.

[0036] The results are shown in Table 1.

[0037] [Table 1]

[0038] In the laminate of Example 1, the polyester layer did not break when peeled off, and no polyester layer remained on the paper layer, and there was no problem when using this to produce a laminate having a corrugated board structure. In the laminate of Comparative Example 1, the polyester layer did not break when peeled off, and no polyester layer remained on the paper layer. However, when this laminate was used to manufacture a laminate having a cardboard structure, the polyester layer peeled off. In the laminate of Comparative Example 2, when the polyester layer was peeled off, the polyester layer remained on the paper layer. In the laminate of Comparative Example 3, the polyester layer broke when it was peeled off. In the laminate of Comparative Example 4, the polyester layer was difficult to peel off, and the polyester layer remained on the paper layer. [Explanation of symbols]

[0039] 1: Paper layer (one liner) 2: Polyester layer 3: Core 4: The other liner 5: Cardboard

Claims

1. A paper layer and a polyester layer are laminated together, The thickness of the polyester layer is 10 to 20 μm, The laminate has a peel strength of 0.7 to 1.3 N / 25 mm when the polyester layer is peeled from the paper layer.

2. The laminate according to claim 1 , wherein the paper layer and the polyester layer are directly laminated together.

3. 3. The laminate according to claim 1, wherein the paper layer is kraft paper or recycled paper.

4. 3. The laminate according to claim 1, further comprising a core and a liner laminated in this order on the surface of the paper layer opposite to the polyester layer.

5. laminating a polyester layer to a paper layer; The thickness of the polyester layer is 10 to 20 μm, The method for producing a laminate, wherein the resulting laminate has a peel strength of 0.7 to 1.3 N / 25 mm when the polyester layer is peeled from the paper layer.

6. The method for producing a laminate according to claim 5 , wherein the polyester layer is directly laminated onto the paper layer.

7. 7. The method for producing a laminate according to claim 5 or 6, further comprising subjecting the paper layer to a corona discharge treatment before laminating the polyester layer onto the paper layer, and adjusting the output of the corona discharge treatment so that the peel strength is 0.7 to 1.3 N / 25 mm.

8. A container comprising the laminate according to any one of claims 1 to 4.

9. A container material comprising the laminate according to any one of claims 1 to 4.

10. A method for manufacturing a container, which uses the laminate according to any one of claims 1 to 4, or includes a method for manufacturing the laminate according to any one of claims 5 to 7.

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