Adhesive tape

Abstract

To provide an adhesive tape that is completely free from problems of abrasion and peeling of a printing layer, limitation on ink to be used for the printing layer, and the problem of detachment of the printing layer, and that uses a paper substrate gentle to the environment.SOLUTION: An adhesive tape comprises a first substrate, a second substrate, an adhesive layer and a printing layer. The printing layer is disposed between the first substrate and the second substrate. The adhesive layer is disposed on a side where the printing layer of the first substrate is not present. The first substrate and the second substrate are composed of a glassine paper, or the first substrate is composed of a transparent plastic, and the second substrate is composed of a glassine paper. The adhesive tape is advantageously used for binding of vegetables or fresh flowers, sealing of container packaging or a packaging bag for food, or identifiable display of commodities.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an adhesive tape that uses environmentally friendly paper as a substrate, that is free from problems of abrasion or peeling of the printed layer, and that has no restrictions on the ink that can be used for the printed layer, and in particular, to an adhesive tape that is suitable for use in bundling vegetables or fresh flowers, or for sealing food containers or packaging bags, or for identifying products. [Background technology]

[0002] Conventionally, adhesive tapes have been used for bundling vegetables or fresh flowers, sealing food containers or packaging bags, or for identifying products. Conventionally, adhesive tapes have included a printed layer on which letters, symbols, or designs representing the name of the sender of the vegetables or fresh flowers, the brand name, the name of the retailer, a barcode, a QR code (registered trademark), or the like are printed with ink (see, for example, Patent Documents 1 and 2). Such adhesive tapes generally have a substrate, an adhesive layer, and a printed layer, and the substrate is typically made of paper or a plastic film. The problems associated with such conventional adhesive tapes will be described below with reference to FIGS. 1 and 2.

[0003] Figure 1 shows an example of a conventional adhesive tape with an adhesive layer and a printed layer on each side of the substrate. This type of adhesive tape typically uses paper as the substrate material, but the printed layer is exposed on the surface of the adhesive tape. For example, when used to bundle vegetables such as green onions, if adjacent vegetables come into contact with each other and rub against each other during display in a store, the letters, symbols, and designs on the printed layer can wear away and become faded, making it difficult for consumers to read information such as the shipper's name and brand name. If the friction is too great, the printed layer can peel off, making the information completely unreadable. Furthermore, while this type of adhesive tape is expected to be used in applications where it may come into contact with food, there is a problem in that only inks that comply with the Food Sanitation Act can be used on the printed layer, which may come into direct contact with food. Furthermore, since this type of adhesive tape is generally sold in a wound roll form, a release layer is formed on the printed layer to make it easier to unwind when used. However, when the release agent for this release layer is applied, the ink in the printed layer dissolves, and there is a risk that the printed layer will peel off when the adhesive tape is unwound.

[0004] To overcome the problems of the adhesive tape of the type shown in Figure 1, the adhesive tape of the type shown in Figure 2 has been proposed. Figure 2 shows an example of a conventional adhesive tape in which a printed layer is disposed between the adhesive layer and the substrate. This type of adhesive tape typically uses transparent plastic as the substrate material. However, unlike the type shown in Figure 1, the printed layer is not exposed on the surface of the adhesive tape and is covered by the substrate, eliminating the drawbacks and problems of the type shown in Figure 1. However, in the case of the type shown in Figure 2, the printed layer is in direct contact with the adhesive layer. Therefore, if the adhesive and the adherend have stronger adhesion than the substrate and the printed layer, the printed layer may detach from the substrate when the tape is peeled off, remaining on the adherend along with the adhesive layer. Furthermore, this type of adhesive tape has the problem of being environmentally unfriendly because it uses a plastic substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 56-26968 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-35071 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been devised to solve the problems of the prior art described above, and its object is to provide an adhesive tape that uses an environmentally friendly paper substrate, which is free from the problems of abrasion and peeling of the printed layer, has no restrictions on the ink that can be used for the printed layer, and is free from the problem of separation of the printed layer. [Means for solving the problem]

[0007] As a result of extensive research to achieve the above object, the present inventors have found that, in an adhesive tape having a paper substrate as shown in Figure 1, by placing another transparent substrate on the side of the printed layer where the paper substrate is not present and covering the surface of the printed layer with another transparent substrate, it is possible to maintain the visibility of the printed layer while avoiding the problems of abrasion and peeling of the printed layer and limitations on the ink used for the printed layer. The inventors have also found that using highly transparent "glassine paper" instead of transparent plastic as this other transparent substrate can also be environmentally friendly. In particular, unlike ordinary papers such as crepe paper and Japanese paper, which have traditionally been commonly used as paper substrates for adhesive tapes, "glassine paper" does not contain a filler resin, making it more recyclable than ordinary paper and more environmentally friendly. Furthermore, because "glassine paper" does not contain a filler resin, it has high heat resistance and is less susceptible to heat shrinkage, making it suitable for pitch printing, in which the same design is repeatedly printed. Furthermore, the "glassine paper" is processed under high pressure during production, making it smoother than ordinary paper, and therefore providing better adhesion between adjacent layers.

[0008] The present invention was completed based on the above findings and has the following features (1) to (6). (1) An adhesive tape comprising a first substrate, a second substrate, an adhesive layer, and a printed layer, wherein the printed layer is disposed between the first substrate and the second substrate, and the adhesive layer is disposed on the side of the first substrate where the printed layer is not present, and wherein the first substrate and the second substrate are made of glassine paper. (2) An adhesive tape comprising a first substrate, a second substrate, an adhesive layer, and a printed layer, wherein the printed layer is disposed between the first substrate and the second substrate, and the adhesive layer is disposed on the side of the first substrate where the printed layer is not present, and wherein the first substrate is made of transparent plastic and the second substrate is made of glassine paper. (3) The adhesive tape according to (2), characterized in that the transparent plastic is a PET film, a polypropylene film, or a polyethylene film. (4) A pressure-sensitive adhesive tape according to (1) or (2), characterized in that a primer layer is disposed between the pressure-sensitive adhesive layer and the first substrate, an adhesive layer is disposed between the printing layer and the second substrate, and a release agent layer is disposed on the side of the second substrate where the adhesive layer is not present. (5) A pressure-sensitive adhesive tape according to (1) or (2), characterized in that a primer layer is disposed between the pressure-sensitive adhesive layer and the first substrate, an adhesive layer is disposed between the first substrate and the printed layer, and a release agent layer is disposed on the side of the second substrate where the printed layer is not present. (6) The adhesive tape according to (1) or (2), characterized in that the adhesive tape is used for bundling vegetables or fresh flowers, for sealing food containers or packaging bags, or for identifying and labeling products. [Effects of the Invention]

[0009] The adhesive tape of the present invention covers the surface of the printed layer with highly transparent "glassine paper," thereby avoiding problems of abrasion and peeling of the printed layer and limitations on the ink used for the printed layer while maintaining the visibility of the printed layer. Furthermore, unlike ordinary paper such as crepe paper or Japanese paper, "glassine paper" does not contain a sealing resin, making it more recyclable than these papers and more environmentally friendly. Furthermore, the adhesive tape of the present invention uses "glassine paper," which is highly heat-resistant and resistant to heat shrinkage, making it suitable for pitch printing, in which the same design is repeatedly printed. Furthermore, the adhesive tape of the present invention uses "glassine paper," which is smoother than ordinary paper, and therefore has excellent adhesion to adjacent layers. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 shows a schematic diagram of an example of the layer structure of a conventional pressure-sensitive adhesive tape. [Figure 2] FIG. 2 is a schematic diagram showing another example of the layer structure of a conventional adhesive tape. [Figure 3] FIG. 3 is a schematic diagram showing an example of the layer structure of the pressure-sensitive adhesive tape of the present invention. [Figure 4] FIG. 4 is a schematic diagram showing another example of the layer structure of the pressure-sensitive adhesive tape of the present invention. [Figure 5] FIG. 5 is a schematic diagram showing an example of a manufacturing procedure for the pressure-sensitive adhesive tape of the present invention. [Figure 6] FIG. 6 shows an example of the use of the adhesive tape of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The pressure-sensitive adhesive tape of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto. Note that the drawings are schematic for the purpose of explanation, and the thickness ratios of each layer may differ from the actual ones.

[0012] The adhesive tape of the present invention comprises two substrates, an adhesive layer, and a printed layer as basic constituent layers, and is suitably used, for example, for binding vegetables such as horenso or fresh flowers such as chrysanthemums, for sealing container packaging or packaging bags for food such as prepared dishes, for identifying purchased products to prevent shoplifting, or for identifying products to detect if they have been opened.

[0013] An example of the layer configuration of the pressure-sensitive adhesive tape of the present invention is shown in Figure 3. The pressure-sensitive adhesive tape of Figure 3 has a basic structure in which a printed layer is disposed between a first substrate and a second substrate, and a pressure-sensitive adhesive layer is disposed on the side of the first substrate where the printed layer is not present. The pressure-sensitive adhesive tape of Figure 3 can further, if necessary, have a primer layer disposed between the pressure-sensitive adhesive layer and the first substrate, an adhesive layer disposed between the printed layer and the second substrate, and a release agent layer disposed on the second substrate. Taking these into consideration, the pressure-sensitive adhesive tape of the present invention has a basic structure in which, from the side intended to face the adherend, a pressure-sensitive adhesive layer, a first substrate, a printed layer, and a second substrate are disposed, in that order, and if necessary, a primer layer is disposed between the pressure-sensitive adhesive layer and the first substrate, an adhesive layer is disposed between the printed layer and the second substrate, and a release agent layer is disposed on the side of the second substrate where the adhesive layer is not present.

[0014] In the present invention, the adhesive layer is provided to adhere the adhesive tape to the substrate. Examples of materials that can be used for the adhesive layer include conventionally known adhesives such as acrylic adhesives, rubber adhesives, silicone adhesives, epoxy adhesives, and urethane adhesives. It is preferable to select an adhesive layer that has sufficient adhesive strength to adhere the adhesive tape to the substrate. It is also preferable to select an adhesive layer that does not leave any adhesive residue when peeled off and has sufficient adhesive strength to ensure sufficient adhesion when re-applied, if necessary. Specifically, it is preferable to select an adhesive layer that has an adhesive strength of, for example, 0.5 to 6.0 N / 10 mm, preferably 1.0 to 5.0 N / 10 mm, at the time of initial application and, for example, 0.3 to 5.0 N / 10 mm, preferably 0.5 to 4.0 N / 10 mm, at the time of re-application. The thickness of the adhesive layer is, for example, 2 to 70 μm, preferably 10 to 50 μm.

[0015] In the present invention, the first substrate serves as a support for the pressure-sensitive adhesive tape and also serves to prevent the problem of the printed layer from coming into direct contact with the pressure-sensitive adhesive layer by being disposed between the pressure-sensitive adhesive layer and the printed layer.

[0016] In the present invention, the first substrate is preferably made of glassine paper from the perspective of recyclability, but it can also be made of transparent plastic. Glassine paper is a high-density paper made from sulfite pulp that has been finely beaten for a long period of time, and is manufactured by high-pressure processing using a smooth roller known as a supercalender. Unlike ordinary papers such as crepe paper and Japanese paper, which have traditionally been commonly used as paper substrates for adhesive tapes, glassine paper does not contain a filler resin, making it more recyclable than ordinary paper and more environmentally friendly. Furthermore, because glassine paper does not contain a filler resin, it has high heat resistance and is less susceptible to thermal shrinkage. Therefore, it is also suitable for forming a printing layer by pitch printing, in which the same design is repeatedly printed. Furthermore, glassine paper is processed under high pressure during production, making it smoother and more transparent than ordinary paper.

[0017] The thickness of the glassine paper constituting the first substrate is preferably 5 to 50 μm, more preferably 10 to 40 μm, in order to balance the strength as a support and flexibility during handling. Various types of glassine paper constituting the first substrate are commercially available, and those skilled in the art can appropriately select a suitable one from these.

[0018] In the present invention, the first substrate does not necessarily have to be made of glassine paper, but can also be made of transparent plastic. Transparent plastics that have conventionally been used as substrates for adhesive tapes can be used, such as PET film, polypropylene film, or polyethylene film. The thickness of these films is preferably 5 to 50 μm, more preferably 10 to 40 μm, in order to strike a balance between the strength as a support and flexibility during handling. Various types of these films are commercially available, so those skilled in the art can appropriately select a suitable one from among them.

[0019] In the present invention, the printed layer is a layer on which letters, symbols, designs, etc. are printed with ink. For example, it can display information such as the name of the sender of vegetables or fresh flowers, the brand name, the name of the retailer, a barcode, or a QR code (registered trademark). In the present invention, the printed layer is not exposed on the surface of the adhesive tape and is covered by a second substrate. Therefore, in the adhesive tape of the present invention, the printed layer is unlikely to come into direct contact with food, so inks other than those complying with the Food Sanitation Act can be used, and there are no restrictions on the ink used for the printed layer. The printed layer can be formed by a conventionally known method. For example, the printed layer can be formed by gravure printing a solvent-based colored ink, followed by drying and curing, and in particular, by pitch printing, in which the same design is repeatedly printed. The thickness of the printed layer is, for example, 0.1 to 5 μm, preferably 0.3 to 3 μm.

[0020] The present invention is characterized in that the second substrate is made of glassine paper. Glassine paper is translucent and has higher transparency than crepe paper and Japanese paper, which have traditionally been commonly used as paper substrates for adhesive tapes. Therefore, glassine paper can be used to cover a printed layer as a substitute for a transparent plastic substrate without causing problems with visibility. Glassine paper is also more recyclable than regular paper and is more environmentally friendly. Furthermore, glassine paper has superior smoothness compared to regular paper, and therefore also has excellent adhesion between adjacent layers. The thickness of the glassine paper constituting the second substrate is preferably 5 to 50 μm, more preferably 10 to 40 μm, in order to balance the strength required to cover the printed layer and flexibility during handling. As with the first substrate, a suitable glassine paper can be appropriately selected from various commercially available products.

[0021] In the pressure-sensitive adhesive tape of the present invention, a primer layer can be disposed between the pressure-sensitive adhesive layer and the first substrate, if necessary. The primer layer serves to improve adhesion between the pressure-sensitive adhesive layer and the first substrate. The constituent material of the primer layer can be appropriately selected depending on the constituent material of the pressure-sensitive adhesive layer, and for example, acrylic, rubber, urethane, epoxy, or other resins can be used. The thickness of the primer layer is, for example, 0.08 to 5 μm, preferably 0.5 to 3 μm.

[0022] In the pressure-sensitive adhesive tape of the present invention, an adhesive layer can be disposed between the printed layer and the second substrate, or between the first substrate and the printed layer, if necessary. The adhesive layer serves to improve adhesion between the printed layer and the substrate. Conventional adhesives such as a solution-type urethane resin adhesive, an epoxy resin adhesive, or a polyester resin adhesive can be used as the adhesive constituting the adhesive layer. The thickness of the adhesive layer is, for example, 0.1 to 10 μm, preferably 1 to 5 μm.

[0023] In the pressure-sensitive adhesive tape of the present invention, a release agent layer can be disposed on the second substrate as needed. The release agent layer serves to facilitate unwinding of the pressure-sensitive adhesive tape wound in a roll when in use. Examples of materials that can be used for the release agent layer include known release treatment agents such as long-chain alkyl-based release agents and silicone-based release agents. The basis weight of the release agent layer is, for example, 0.1 to 10 g / m 2 , preferably 0.1 to 3 g / m 2 is.

[0024] Next, another example of the layer structure of the pressure-sensitive adhesive tape of the present invention is shown in Figure 4. The pressure-sensitive adhesive tape of Figure 4 has the same layer structure as that of Figure 3, except that the position of the adhesive layer is different from that of the pressure-sensitive adhesive tape of Figure 3. That is, in Figure 3, the adhesive layer is disposed between the printed layer and the second substrate, whereas in Figure 4, the adhesive layer is disposed between the first substrate and the printed layer. This difference in arrangement arises from the fact that Figure 3 corresponds to a type in which the printed layer is front-printed, whereas Figure 4 corresponds to a type in which the printed layer is reverse-printed. In the pressure-sensitive adhesive tape of the present invention, the second substrate is made of highly transparent glassine paper, so that fine information such as barcodes and QR codes (registered trademark) can be sufficiently read even in reverse-printed types such as those shown in Figure 4.

[0025] Next, the manufacturing procedure of the pressure-sensitive adhesive tape of the present invention will be described with reference to Fig. 5. The pressure-sensitive adhesive tape of the present invention can be manufactured appropriately using a conventionally known method. For example, in the case of the type shown in Fig. 3, the pressure-sensitive adhesive tape can be manufactured by the following procedure.

[0026] First, letters, symbols, designs, etc. are printed with ink on one side of glassine paper, which serves as the first substrate, to form a printed layer. Next, a primer is applied to the side of the glassine paper opposite the printed layer to form a primer layer, resulting in a laminate (1) as shown in the upper left of Figure 5. Meanwhile, a release agent is applied to one side of glassine paper, which serves as the second substrate, to form a release agent layer. Next, an adhesive is applied to the side of the glassine paper opposite the release agent layer to form an adhesive layer, resulting in a laminate (2) as shown in the upper right of Figure 5. Next, these laminates (1) and (2) are bonded together so that the printed layer of laminate (1) contacts the adhesive layer of laminate (2), resulting in a laminate (3) as shown in the lower left of Figure 5. Finally, an adhesive is applied to the primer layer of this laminate (3) to form an adhesive layer, resulting in an adhesive tape as shown in the lower right of Figure 5.

[0027] In the case of the type shown in FIG. 4, adhesive tapes can be manufactured in a similar manner by changing the procedure for forming the laminate (1) and the laminate (2) depending on the difference in layer structure.

[0028] The pressure-sensitive adhesive tape of the present invention thus produced can be provided in a roll form by being wound around a core for ease of handling. In the case of a roll-type pressure-sensitive adhesive tape, it can be used by unwinding and cutting only the required length.

[0029] Next, specific examples of use of the pressure-sensitive adhesive tape of the present invention are shown in Figure 6. In Figure 6, Example 1 is an example of use for bundling vegetables such as spinach, Example 2 is an example of use for sealing container packaging for food such as prepared dishes, Example 3 is an example of use for identifying purchased products to prevent shoplifting, and Example 4 is an example of use for identifying products to detect whether they have been opened. In addition to these, the pressure-sensitive adhesive tape of the present invention can also be used as a tape for manufacturing processes, taking advantage of its good heat resistance and low heat shrinkage.

[0030] The effects of the pressure-sensitive adhesive tape of the present invention will be demonstrated by the following examples, but the present invention is not limited to these. [Example]

[0031] Example of the present invention As an example of the present invention, an adhesive tape was produced in which the layers were laminated in the order shown in Figure 3. The constituent materials and layer thicknesses of each layer of the adhesive tape are as shown in Table 1 below.

[0032] [Table 1] ---------------------------------------------------------------------------------- Layer Material Thickness (μm) ---------------------------------------------------------------------------------- Release agent layer Long chain alkyl release agent 0.5 Second base material: Glassine paper 31.5 Adhesive layer Polyester resin 3.0 Printing layer Printing ink (solvent type) 1.0 First base material: Glassine paper 31.5 Primer layer Rubber resin 1.0 Adhesive layer: Rubber adhesive 25.0 ----------------------------------------------------------------------------------

[0033] Specifically, a barcode was first printed repeatedly on one side of glassine paper, which served as the first substrate, using a solvent-based printing ink to form a printed layer. Next, a rubber-based resin was applied as a primer to the side of the glassine paper opposite the printed layer to form a primer layer, resulting in a laminate (1) as shown in the upper left of Figure 5. Meanwhile, a long-chain alkyl-based release agent was applied as a release agent to one side of glassine paper, which served as the second substrate, to form a release agent layer. Next, a polyester-based resin adhesive was applied as an adhesive to the side of the glassine paper opposite the release agent layer to form an adhesive layer, resulting in a laminate (2) as shown in the upper right of Figure 5. Next, these laminates (1) and (2) were bonded together so that the printed layer of laminate (1) was in contact with the adhesive layer of laminate (2), resulting in a laminate (3) as shown in the lower left of Figure 5. Finally, a rubber-based adhesive was applied as an adhesive onto the primer layer of this laminate (3) to form an adhesive layer, thereby completing an adhesive tape as shown in the lower right of FIG.

[0034] The visibility of the barcode on the printed layer of the produced adhesive tape and its readability by a reader were checked, and they were found to be at a level that posed no practical problems. Furthermore, pitch printing was also performed without any problems, and despite the thin thickness of the primer layer and adhesive layer, the adhesiveness with the adjacent layers was excellent.

[0035] Comparative Example As a comparative example, an adhesive tape was produced in the same manner as in the present invention, except that the constituent materials of the first and second substrates were changed to 31.5 μm thick Japanese paper, which is commonly used as a paper substrate for adhesive tapes. However, at the time of pitch printing of the printing layer, the Japanese paper of the first substrate thermally shrunk due to the sealing resin contained therein, and proper pitch printing could not be performed.

[0036] Furthermore, when the visibility of the barcode on the printed layer of the produced adhesive tape and its readability by a reader were checked, the barcode was barely visible and could not be read by a reader. Furthermore, because Japanese paper has an uneven surface, it has poor adhesion to adjacent layers, and it was necessary to increase the thickness of the primer layer and adhesive layer. [Industrial Applicability]

[0037] The pressure-sensitive adhesive tape of the present invention can solve the conventional problems of abrasion and peeling of the printed layer and limitations on the ink used for the printed layer while maintaining the visibility of the printed layer. Furthermore, the pressure-sensitive adhesive tape of the present invention is not only highly recyclable and environmentally friendly, but also suitable for pitch printing, in which the same design is repeatedly printed, and has excellent adhesion between adjacent layers. Therefore, the pressure-sensitive adhesive tape of the present invention can be suitably used for bundling various materials, sealing various containers and bags, or identifying products.

Claims

1. An adhesive tape comprising a first substrate, a second substrate, an adhesive layer, and a printed layer, wherein the printed layer is disposed between the first substrate and the second substrate, and the adhesive layer is disposed on the side of the first substrate where the printed layer is not present, and wherein the first substrate and the second substrate are made of glassine paper.

2. An adhesive tape comprising a first substrate, a second substrate, an adhesive layer, and a printed layer, wherein the printed layer is disposed between the first substrate and the second substrate, and the adhesive layer is disposed on the side of the first substrate where the printed layer is not present, and wherein the first substrate is made of transparent plastic and the second substrate is made of glassine paper.

3. 3. The adhesive tape according to claim 2, wherein the transparent plastic is a PET film, a polypropylene film, or a polyethylene film.

4. 3. The pressure-sensitive adhesive tape according to claim 1, wherein a primer layer is disposed between the pressure-sensitive adhesive layer and the first substrate, an adhesive layer is disposed between the printing layer and the second substrate, and a release agent layer is disposed on the side of the second substrate where the adhesive layer is not present.

5. 3. The pressure-sensitive adhesive tape according to claim 1, wherein a primer layer is disposed between the pressure-sensitive adhesive layer and the first substrate, an adhesive layer is disposed between the first substrate and the printed layer, and a release agent layer is disposed on the side of the second substrate where the printed layer is not present.

6. 3. The adhesive tape according to claim 1 or 2, which is used for bundling vegetables or fresh flowers, for sealing food containers or packaging bags, or for identifying and marking products.

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