JP2024083272A - Colored adhesive tape and method for producing the same - Google Patents

Abstract

[Problem] To provide a thin colored adhesive tape with a high rate of recycled materials. [Solution] To provide a colored adhesive tape having a substrate 1, a colored layer 2 provided on one side of the substrate, an adhesive layer 3 provided on the other side of the substrate, and a release liner 4 provided on the surface of the adhesive layer, wherein at least the substrate and the release liner each contain recycled resin, the total thickness of the colored adhesive tape 10 excluding the release liner is 20 μm or less, and the rate of recycled materials in the colored adhesive tape is 70 mass % or more. [Selected Figure] Figure 1

Description

The present invention relates to a thin colored adhesive tape that has a colored layer and is made from a high percentage of recycled materials.

For example, in the case of portable electronic devices, colored adhesive tapes with a colored layer are used to combine functions such as a light-blocking effect by coloring them black, improved brightness by coloring them white, and the ability to hide defects in the appearance of parts (unevenness, dot defects, etc.) and improve their appearance by coloring them.

In recent years, however, there has been a demand for resin products with a high proportion of recycled materials (hereinafter sometimes referred to as "recycled material rate") in order to reduce the environmental burden, such as by reducing carbon dioxide emissions. One such resin product is, for example, a recycled resin film made from recycled resin that has been recovered and regenerated from used resin.

For example, Patent Document 1 discloses a laminate having a polyester film substrate that contains chemically recycled polyester resin.

Patent Document 2 also discloses a biaxially oriented polyester film that contains a specified proportion of recycled polyester resin made from PET bottles.

JP 2022-7900 A International Publication No. 2022/071440

Colored adhesive tapes, which have a colored layer, adhesive layer, substrate, and release liner as their constituent parts, are made with many of their constituent parts made from petroleum resins. For this reason, from the perspective of environmental considerations, there is a demand to increase the recycled material rate in colored adhesive tapes as a whole.

The present invention was made in consideration of the above problems, and aims to provide a thin colored adhesive tape with a high recycled material rate.

The present invention includes the following embodiments.
[1] A colored adhesive tape comprising a substrate, a colored layer provided on one side of the substrate, an adhesive layer provided on the other side of the substrate, and a release liner provided on the surface of the adhesive layer, wherein at least the substrate and the release liner each contain a recycled resin, the total thickness of the colored adhesive tape excluding the release liner is 20 μm or less, and the proportion of recycled raw materials in the colored adhesive tape is 70 mass% or more.

[2] The colored adhesive tape of [1] above, in which the thickness of the substrate is 9 μm or less, and the substrate has a single-layer structure having one layer in which the recycled resin content is 50% by mass or more and 100% by mass or less and the mechanical recycled resin content is 95% by mass or less, or a two-layer structure having two of the above layers.

[3] The colored adhesive tape of [1] or [2] above, in which the release liner has a single-layer structure in which the recycled resin content is 50% by mass or more and 100% by mass or less and the mechanical recycled resin content is 95% by mass or less, or a multilayer structure in which the outermost layer on the adhesive layer side is a layer in which the recycled resin content is 50% by mass or more and 100% by mass or less and the mechanical recycled resin content is 95% by mass or less, or a layer in which the virgin resin content is 50% by mass or more.

[4] A colored adhesive tape according to any one of [1] to [3] above, in which the content of recycled resin in the release liner is 90% by mass or more.

[5] A colored adhesive tape according to any one of [1] to [4] above, in which the thickness of the adhesive layer is 9 μm or less.

[6] The colored adhesive tape according to any one of [1] to [5] above, wherein the release liner has a three-layer structure having, from the adhesive layer side, a layer B1, a layer B2, and a layer B3 in this order, the layer B1 and the layer B3 each have a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanically recycled resin content of 95% by mass or less, or a virgin resin content of 50% by mass or more, and the layer B2 has a mechanically recycled resin content of 50% by mass or more and 100% by mass or less.

[7] The colored adhesive tape according to any one of [1] to [6] above, wherein the recycled resin contained in the release liner is a recycled polyester resin.

[8] A colored adhesive tape according to any one of [1] to [7] above, wherein the recycled resin contained in the substrate is a recycled polyester resin.

[9] The colored adhesive tape according to any one of [1] to [8] above, wherein the colored adhesive tape contains a biomass material, and the proportion of recycled materials and biomass materials in the colored adhesive tape is 75% by mass or more.

[10] A method for producing a colored adhesive tape according to any one of [1] to [9] above, comprising a colored layer forming step of forming a colored layer on one side of a substrate containing recycled resin, an adhesive layer forming step of applying an adhesive to the other side of the substrate to form an adhesive layer, and a laminating step of laminating a release liner containing recycled resin to the surface of the adhesive layer.

[11] A method for producing a colored adhesive tape according to any one of [1] to [9] above, comprising an adhesive layer forming step of applying an adhesive to a release liner containing recycled resin to form an adhesive layer to obtain a release liner with an adhesive layer, a colored layer forming step of forming a colored layer on one side of a substrate containing recycled resin, and a lamination step of laminating the adhesive layer side of the release liner with adhesive layer to the other side of the substrate.

[12] A method for producing a colored adhesive tape according to any one of [1] to [9] above, comprising an adhesive layer forming step of applying an adhesive to one side of a substrate containing a recycled resin to form an adhesive layer, a laminating step of laminating a release liner containing a recycled resin to the surface of the adhesive layer, and a colored layer forming step of forming a colored layer on the other side of the substrate.

[13] A method for producing a colored adhesive tape according to any one of [1] to [9] above, comprising: an adhesive layer forming step of applying an adhesive to a release liner containing a recycled resin to form an adhesive layer, thereby obtaining a release liner with an adhesive layer; a laminating step of laminating a substrate containing a recycled resin to the surface of the adhesive layer of the release liner with an adhesive layer; and a colored layer forming step of forming a colored layer on the surface of the substrate.

The present invention provides a thin colored adhesive tape with a high recycled material content.

1 is a schematic cross-sectional view showing an example of the colored pressure-sensitive adhesive tape of the present invention. 1 is a schematic cross-sectional view showing an example of the colored pressure-sensitive adhesive tape of the present invention. 1 is a schematic cross-sectional view showing an example of the colored pressure-sensitive adhesive tape of the present invention.

In this specification, recycled resin refers to resin obtained by recycling recovered used resin, and examples of such resin include chemically recycled resin and mechanically recycled resin. In addition, recycled resin may be petroleum resin made from petroleum resources, biomass resin made from non-petroleum resources (biomass resources) such as plants, or a mixture of these. The used resin that is the raw material for recycled resin may be petroleum resin, biomass resin, chemically recycled resin, mechanically recycled resin, or a mixture of these.

In this specification, mechanically recycled resin refers to resin obtained by cleaning and crushing recovered used resin, melting it at high temperature, and then extruding it (mechanical recycling method).

In this specification, chemically recycled resin refers to a resin obtained by separating, crushing, and washing recovered used resin to remove impurities, and then decomposing and purifying it into raw materials or intermediate raw materials for resin by depolymerization, and then polymerizing it again (chemical recycling method). Chemically recycled resin is obtained by directly repolymerizing the oligomer mixture without adding other functional additives during the regeneration process, but it may also be electrostatically adhesive chemically recycled resin obtained by adding an electrostatic adhesive agent to the oligomer mixture and then repolymerizing it. Electrostatically adhesive chemically recycled resin includes chemically recycled resin and electrostatic adhesive agent.

In this specification, virgin resin refers to unused resin, i.e., non-recycled resin, which is resin that does not use used raw materials. Virgin resin may be petroleum resin, biomass resin, or a mixture of these.

In this specification, the ratio of recycled materials in the colored adhesive tape (recycled material ratio of the colored adhesive tape) refers to the mass ratio of recycled materials used in the manufacture of the colored adhesive tape to the total mass of the colored adhesive tape including the release liner. Furthermore, the ratio of recycled materials in each layer constituting the colored adhesive tape (recycled material ratio of each layer constituting the colored adhesive tape) refers to the mass ratio (mass%) of recycled materials used in forming each layer to the mass of each layer. Note that the unit of recycled material ratio (mass%) may be simply expressed as %.

The recycled material rate of the colored adhesive tape can be calculated by the following formula.
Recycled material rate of colored adhesive tape (%) = [(recycled material rate of each raw material used in manufacturing the colored adhesive tape) x (sum of (mass of each raw material used in manufacturing the colored adhesive tape)] / (total mass of the colored adhesive tape)

The recycled material rate of each layer constituting the colored adhesive tape can be calculated by the following formula.
Recycled material rate (%) of each layer constituting the colored adhesive tape = [(recycled material rate of each raw material used in manufacturing the layers constituting the colored adhesive tape) x (sum of (mass of each raw material used in manufacturing the layers constituting the colored adhesive tape)] / (mass of the layers constituting the colored adhesive tape)

In this specification, the ratio of biomass raw materials in the colored adhesive tape (biomass degree of the colored adhesive tape) refers to the ratio of the biomass-derived raw materials used in the production of the colored adhesive tape to the total mass of the colored adhesive tape. The ratio of biomass raw materials in each layer constituting the colored adhesive tape (biomass degree of each layer) refers to the mass ratio of the biomass-derived raw materials used in forming each layer to the mass of each layer. Specifically, since the minimum biomass degree value of each biomass-derived raw material is provided by the raw material manufacturer, the biomass degree, which is the ratio (mass %) of the biomass-derived raw materials in the mass of the colored adhesive tape and each layer constituting the colored adhesive tape, can be calculated based on the minimum biomass degree of each biomass-derived raw material provided by these raw material manufacturers and the blending amount of each biomass-derived raw material. The ratio of biomass raw materials may be simply referred to as "biomass degree" or "biomass raw material ratio". The unit of biomass degree (mass %) may also be expressed simply as %.

The biomass degree of the colored adhesive tape can be calculated by the following formula.
Biomass content (%) of colored adhesive tape = (biomass content of each biomass-derived raw material used in producing the colored adhesive tape) x (sum of mass of each biomass-derived raw material used in producing the colored adhesive tape)) / (total mass of the colored adhesive tape)

The biomass degree of each layer constituting the colored pressure-sensitive adhesive tape can be calculated by the following formula.
Biomass content (%) of each layer constituting the colored adhesive tape=[biomass content of each raw material derived from biomass used in producing a layer constituting the colored adhesive tape)×(sum of mass of each raw material derived from biomass used in producing a layer constituting the colored adhesive tape)]/(mass of layer constituting the colored adhesive tape).

The biomass degree of the colored adhesive tape and each layer that constitutes the colored adhesive tape can also be calculated by measuring the concentration of radioactive carbon (C14), which is hardly present in petroleum-derived raw materials, using accelerator mass spectrometry. The biomass degree may be calculated by any one of the above calculation methods as long as the value obtained is within the range described below.

In this specification, the ratio of recycled materials and biomass materials in the colored adhesive tape (referred to as the recycled and biomass raw material ratio) refers to the mass ratio of the recycled materials and biomass-derived raw materials used in the manufacture of the colored adhesive tape in the total mass of the colored adhesive tape. The recycled and biomass raw material ratio of each layer constituting the colored adhesive tape refers to the mass ratio of the recycled materials and biomass-derived raw materials used in forming each layer in the mass of each layer. Specifically, the ratio of recycled materials and the minimum biomass degree of each biomass-derived raw material are provided by the raw material manufacturer, so the ratio (mass%) of recycled materials and biomass raw materials in the mass of the colored adhesive tape and each layer constituting the colored adhesive tape can be calculated based on the minimum recycled material ratio of each recycled material and the minimum biomass degree of each biomass-derived raw material provided by these raw material manufacturers, and the blending amount of the recycled materials and each biomass-derived raw material. The unit (mass%) of the recycled and biomass raw material ratio may be simply expressed as %.

The recycled and biomass raw material ratios of colored adhesive tape can be calculated using the following formula. Note that when the target raw material is both a recycled raw material and a biomass raw material, the overlapping content is excluded from the calculation.
Recycled and biomass raw material rate (%) of colored adhesive tape={[(recycled raw material rate of each raw material used in producing the colored adhesive tape) x (mass of each raw material used in producing the colored adhesive tape)] + (biomass degree of each raw material derived from biomass used in producing the colored adhesive tape) x (mass of each raw material derived from biomass used in producing the colored adhesive tape)]}/(total mass of the colored adhesive tape)

The recycled and biomass raw material ratios of each layer constituting the colored adhesive tape can be calculated by the following formula. Note that when the target raw material is both a recycled raw material and a biomass raw material, the overlapping content is excluded from the calculation.
Recycled and biomass raw material rate (%) of each layer constituting the colored adhesive tape={[(recycled raw material rate of each raw material used in manufacturing the layers constituting the colored adhesive tape)×(mass of each raw material used in manufacturing the layers constituting the colored adhesive tape)]+(biomass degree of each raw material derived from biomass used in manufacturing the layers constituting the colored adhesive tape)×(mass of each raw material derived from biomass used in manufacturing the layers constituting the colored adhesive tape)]}/(mass of the layers constituting the colored adhesive tape)

The recycled material rate, biomass degree, recycled and biomass material rate of each layer constituting the colored adhesive tape of the examples and comparative examples described below, and the colored adhesive tape, are values calculated using the above-mentioned formula.

A. Colored Adhesive Tape The colored adhesive tape of the present invention has a colored layer provided on one surface of the substrate, an adhesive layer provided on the other surface of the substrate, and a release liner provided on the surface of the adhesive layer, wherein at least the substrate and the release liner each contain a recycled resin, the total thickness of the colored adhesive tape excluding the release liner is 20 μm or less, and the proportion of recycled materials in the colored adhesive tape is 70 mass % or more.

Figures 1 to 3 are schematic cross-sectional views showing an example of the colored adhesive tape of the present invention. The colored adhesive tape of the present invention is not limited to the embodiment exemplified in Figures 1 to 3. The colored adhesive tape 10 exemplified in Figures 1 to 3 has a substrate 1, a colored layer 2 provided on one side of the substrate 1, an adhesive layer 3 provided on the other side of the substrate 1, and a release liner 4 provided on the surface of the adhesive layer 3. In the colored adhesive tape 10 exemplified in Figure 1, the substrate 1 and the release liner 4 each have a single-layer structure. In the colored adhesive tape 10 exemplified in Figure 2, the substrate 1 has a single-layer structure, and the release liner 4 has a three-layer structure having, from the adhesive layer 3 side, a layer B1 (reference number 4a in Figure 2), a layer B2 (reference number 4b in Figure 2), and a layer B3 (reference number 4c in Figure 2) in this order. In the colored adhesive tape illustrated in FIG. 3, the substrate 1 has a two-layer structure having, from the adhesive layer 3 side, a layer A1 (reference number 1a in FIG. 3) and a layer A2 (reference number 1b in FIG. 3), in that order, and the release liner 4 has a three-layer structure having, from the adhesive layer 3 side, a layer B1 (reference number 4a in FIG. 2), a layer B2 (reference number 4b in FIG. 2), and a layer B3 (reference number 4c in FIG. 2), in that order.

The colored adhesive tape of the present invention can exhibit a high recycled material rate in a tape configuration that includes a release liner. In particular, since the mass ratio of the release liner and substrate to the total mass of a thin colored adhesive tape is high, the recycled material rate of the colored adhesive tape can be further increased by using a substrate and release liner with a high recycled material rate.

In particular, in the colored pressure-sensitive adhesive tape of the present invention, the substrate preferably has the following structure [1a] or [2a].
[1a] A single-layer structure having one layer in which the content of recycled resin is 50% by mass or more and 100% by mass or less and the content of mechanically recycled resin is 95% by mass or less [2a] A two-layer structure having two of the above layers. Note that the "above layer" in the above [2a] refers to the above [1a] layer. The same applies in the following explanation. In this case, in order to achieve a thin colored adhesive tape, particularly an extremely thin total thickness of several μm, it is more preferable that the thickness of the above substrate is 9 μm or less.

In the colored pressure-sensitive adhesive tape of the present invention, the release liner preferably has the following structure [1b] or [2b].
[1b] A single-layer structure having a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanical recycled resin content of 95% by mass or less. [2b] A multilayer structure in which the outermost layer on the pressure-sensitive adhesive layer side is a layer having a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanical recycled resin content of 95% by mass or less, or a layer having a virgin resin content of 50% by mass or more.

In the colored adhesive tape of the present invention, the reason why the substrate and/or release liner each preferably have the above structure is as follows. The present inventors have found that in a thin colored adhesive tape having a total thickness of 20 μm or less (particularly a total thickness of several μm to several tens of μm), problems such as reduced adhesion and appearance occur when recycled resin films are used for the substrate or release liner. In detail, when the recycled raw material rate of the substrate or release liner in the colored adhesive tape is increased, the substrate or release liner tends to contain a large amount of impurities generated according to the recycling method. When an adhesive layer is formed on a substrate or release liner containing a large amount of impurities, the adhesive layer is likely to have many defects such as fish eyes, surface irregularities, and bubbles due to the above impurities, and as a result, the adhesive strength varies depending on the position on the surface of the adhesive layer, and the adhesive strength of the entire tape is reduced. Similarly, when a colored layer is formed on a substrate or release liner containing a large amount of impurities, the colored layer is likely to have many defects such as ink loss (print loss) due to the above impurities, and as a result, the design and light-shielding properties are impaired and a stable appearance cannot be obtained. In particular, in the case of extremely thin colored adhesive tapes with a total thickness of only a few micrometers, these problems are more likely to occur because the thickness of the adhesive layer and colored layer is extremely thin, at around a few micrometers.

In response to such defects, by making the substrate and release liner that make up a thin colored adhesive tape with a total thickness of 20 μm or less (particularly a total thickness of a few μm to a dozen μm) each have a specific configuration, it is possible to increase the recycled material rate of the colored adhesive tape, and also to prevent the occurrence of fish eyes, surface irregularities, air bubbles, etc. in the adhesive layer, as well as ink loss in the colored layer, when a thin adhesive layer or colored layer is provided on the substrate or release liner, thereby achieving stable adhesion and appearance. Note that fish eyes, surface irregularities, and air bubbles (foaming) that occur in the adhesive layer, as well as ink loss (print loss) that occurs in the colored layer, are sometimes collectively referred to as "defects".

The colored adhesive tape of the present invention has a total thickness of 20 μm or less, excluding the release liner. In order to achieve a thin shape, the total thickness is, for example, 1.5 μm or more, preferably 2.5 μm or more, and more preferably 3 μm or more. Of these, the total thickness is preferably 3 μm or more and 20 μm or less, and since it is possible to exhibit stable adhesion and a high recycled material rate while being thin, the thickness is more preferably 4 μm or more and 15 μm or less, more preferably 4.5 μm or more and 12 μm or less, and even more preferably 5 μm or more and 10 μm or less.

The recycled material rate of the colored adhesive tape of the present invention may be 70% by mass or more from the viewpoint of reducing the environmental load, and is preferably 80% by mass or more to increase the effect of reducing the environmental load, more preferably 85% by mass or more, and even more preferably 87% by mass or more. The recycled material rate of the above-mentioned colored adhesive tape is most preferably 100% by mass or less, but may be 99% by mass or less, or may be 95% by mass or less.

In addition, the colored adhesive tape of the present invention preferably contains a biomass material from the viewpoint of reducing the environmental load. The ratio of recycled materials and biomass materials in the colored adhesive tape of the present invention (recycled and biomass raw material ratio) is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. By making the recycled and biomass raw material ratios of the colored adhesive tape of the present invention within the above ranges, a more environmentally friendly colored adhesive tape can be obtained. The recycled and biomass raw material ratios of the above colored adhesive tape are most preferably 100% by mass or less, but may be 99% by mass or less, or may be 95% by mass or less.

The components constituting the colored adhesive tape of the present invention and the colored adhesive tape are described in detail below.

1. Substrate The substrate in the present invention contains a recycled resin. One surface of the substrate is in contact with the colored layer, and the other surface is in contact with the pressure-sensitive adhesive layer.

(1) Composition The substrate is made of resin, but may contain any material such as additives in addition to the resin. A resin film can be used as the substrate. The content of the resin in the substrate (resin film) is preferably 90% by mass or more and 100% by mass or less, more preferably 95% by mass or more and 100% by mass or less, even more preferably 99% by mass or more and 100% by mass or less, and particularly preferably 99.5% by mass or more and 100% by mass or less. When the substrate has a multilayer structure of two or more layers, the content of the resin in the substrate refers to the proportion of the content of the resin in the total amount of the substrate having a multilayer structure. The resin constituting the substrate includes at least recycled resin, but may also include virgin resin if necessary.

In order to make the recycled material rate of the colored adhesive tape of the present invention equal to or greater than a predetermined value, it is preferable that the substrate contains a recycled resin as a main component. The content of the recycled resin in the substrate may be 50% by mass or more, and is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. The content of the recycled resin in the substrate is most preferably 100% by mass or less, but may be 99% by mass or less, 98% by mass or less, or 95% by mass or less. When the recycled resin is a mixture of two or more types, the content of the recycled resin in the substrate refers to the sum of the contents of the two or more types of recycled resin. When the substrate has a multilayer structure of two or more layers, the content of the recycled resin in the substrate refers to the proportion of the recycled resin content in the total amount of the substrate having a multilayer structure.

The recycled resin constituting the above-mentioned substrate is not particularly limited, and examples thereof include recycled polyester resins such as recycled polyethylene terephthalate (recycled PET), recycled polytrimethylene terephthalate (recycled PTT), recycled polybutylene terephthalate (recycled PBT), recycled polyethylene naphthalate (recycled PEN), and recycled polybutylene naphthalate (recycled PBN); recycled polyolefin resins such as recycled polypropylene (recycled PP) and recycled polyethylene (recycled PE); recycled vinyl chloride resin, recycled styrene resin, recycled vinyl ether resin, recycled polyvinyl alcohol resin, recycled polyamide resin, recycled polycarbonate resin, and recycled polysulfone resin. These may be used alone or in combination of two or more types. The above-mentioned substrate is preferably a resin film containing one or more of these recycled resins.

Among the above-mentioned recycled resins, recycled polyester resin is preferred from the viewpoint of having a large recycled amount and having the strength and flexibility required for the substrate, recycled polyethylene terephthalate (recycled PET) or recycled polytrimethylene terephthalate (recycled PTT) is more preferred, and recycled polyethylene terephthalate (recycled PET) is even more preferred. That is, the above-mentioned substrate is preferably a resin film (polyester film) mainly composed of recycled polyester resin, and more preferably a resin film (PET film) mainly composed of recycled polyethylene terephthalate. Recycled polyester resin has dicarboxylic acid units such as terephthalic acid and isophthalic acid, and diol units such as ethylene glycol. Recycled polyester resin made of PET bottles contains isophthalic acid that controls crystallinity to improve the appearance of the bottle, so it is preferable that the dicarboxylic acid units of the recycled polyester resin contain 95 mol% to 99.5 mol% terephthalic acid units and 0.5 mol% to 5 mol% isophthalic acid units.

The recycled resin is preferably at least one of chemically recycled resin and mechanically recycled resin, since it is possible to obtain a large amount of recycled resin at low cost by using a general-purpose recycling method. In particular, the chemically recycled resin and/or mechanically recycled resin contained in the base material is preferably a chemically recycled polyester resin and/or a mechanically recycled polyester resin, among the recycled resins exemplified above.

The recycled resin is preferably a mechanically recycled resin, since it has an excellent balance between quality and recycling costs and can inexpensively increase the recycled raw material rate of the colored adhesive tape.

The recycled resin is preferably a chemically recycled resin. Because the method of regenerating the recycled resin results in less impurities being mixed into the resin film, it is possible to prevent defects in the adhesive layer and colored layer caused by impurities contained in the substrate (resin film).

The recycled resin may be a mixture of mechanically recycled resin and chemically recycled resin.

The substrate may further contain virgin resin in addition to the recycled resin. By containing both recycled resin and virgin resin in the substrate, the recycled material rate of the substrate can be increased, and the physical properties of the recycled resin, which deteriorate due to the recycling process, can be compensated for by the physical properties of the virgin resin. The virgin resin that can be contained in the substrate is not particularly limited, and can be appropriately selected and used according to the type of recycled resin contained in the substrate. Examples of the virgin resin include polyester resin, polyolefin resin, vinyl chloride resin, styrene resin, vinyl ether resin, polyvinyl alcohol resin, polyamide resin, polycarbonate resin, polysulfone resin, etc. The virgin resin may be a petroleum resin or a resin derived from biomass. In addition, the virgin resin is preferably the same type as the recycled resin. For example, if the recycled resin is a recycled polyester resin, the virgin resin mixed with the recycled resin is preferably a polyester resin.

Examples of polyester resins that can be used as virgin resins include polyethylene terephthalate (PET) resin, polyethylene naphthalate (PEN) resin, polybutylene terephthalate (PBT) resin, polybutylene naphthalate (PBN) resin, polyethylene furanoate (PEF) resin, polytrimethylene terephthalate resin, etc. Among these, it is preferable that the resin is the same type as the above recycled resin, and polyethylene terephthalate (PET) resin is preferred.

The content of virgin resin in the substrate is preferably 50% by mass or less in order to achieve a predetermined recycled material rate or more. In particular, from the viewpoint of suppressing the occurrence of defects in the adhesive layer and colored layer due to impurities contained in the recycled resin and further increasing the recycled material rate of the substrate, the content is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 10% by mass or less, and preferably 0% by mass, i.e., no virgin resin is included.

The substrate preferably contains a biomass material, and more preferably, the recycled resin contains raw materials derived from biomass. The recycled resin containing raw materials derived from biomass means that the recycled resin contains structural units derived from biomass as structural units. By including raw materials derived from biomass in the recycled resin, a more environmentally friendly substrate can be obtained.

For example, polyester resins are obtained by polycondensation of dicarboxylic acids and diols, and contain dicarboxylic acid units and diol units as constituent units. Polyester resins containing biomass-derived constituent units can be synthesized by using biomass-derived raw materials for at least one of the dicarboxylic acids and diols. Examples of biomass-derived diols include ethylene glycol derived from biomass (biomass ethanol) produced from raw materials such as sugarcane and corn. Examples of biomass-derived carboxylic acids include sebacic acid, azelaic acid, isophthalic acid, and terephthalic acid derived from biomass, produced from raw materials such as corn, sugars, and wood.

Therefore, when the recycled resin is a recycled polyester resin, the recycled polyester resin can be a recycled biomass polyester resin by containing a biomass-derived diol unit and/or a biomass-derived carboxylic acid unit. In particular, the recycled resin is preferably a recycled biomass polyethylene terephthalate.

Similarly, when the base material contains a virgin resin, it is preferable that the virgin resin contains a raw material derived from biomass, that is, the virgin resin contains a structural unit derived from biomass as a structural unit. When the virgin resin is a polyester resin, the polyester resin contains a diol unit derived from biomass and/or a carboxylic acid unit derived from biomass, so that the virgin resin can be a biomass material. In particular, it is preferable that the virgin resin is virgin biomass polyethylene terephthalate.

In both recycled biomass polyester resin and virgin biomass polyester resin, the dicarboxylic acid units, which are structural units, may be entirely or partially derived from biomass, but it is preferable that they are entirely derived from biomass. Similarly, the diol units, which are structural units of the polyester resin, may be entirely or partially derived from biomass, but it is preferable that they are entirely derived from biomass.

The biomass degree of the substrate is preferably 10% by mass or more and 100% by mass or less, more preferably 30% by mass or more and 100% by mass or less, and even more preferably 50% by mass or more and 100% by mass or less. The recycled and biomass raw material ratio of the substrate is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 90% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less. By having the biomass degree and recycled and biomass raw material ratio of the substrate within the above ranges, a more environmentally friendly colored adhesive tape can be obtained.

The substrate is made of the resin described above, but may contain any additives in addition to the resin. Examples of additives include lubricants (e.g., inorganic lubricants such as silica, calcium carbonate, and alumina; organic lubricants such as polystyrene resin, polymethyl methacrylate resin, silica gel, acrylic resin, and compositions thereof), electrostatic adhesion agents (e.g., metal salts containing alkali metals or alkaline earth metals such as sodium hydroxide and potassium hydroxide, and metal salts containing aliphatic carboxylic acids), metal catalysts (e.g., antimony, germanium, titanium, and mixtures thereof), pigments, antioxidants, antistatic agents, UV absorbers, stabilizers, degradable materials (e.g., biopolymers such as starch, cellulose, chitin, polylactic acid, and polyglycolic acid; natural materials such as natural rubber), and the like.

(2) Properties The thickness of the substrate is not particularly limited as long as the thickness of the colored adhesive tape excluding the release liner is within a predetermined range, and can be, for example, 18.5 μm or less, preferably 18.0 μm or less, preferably 13.5 μm or less, and preferably 12 μm or less. In particular, in terms of the relationship between the thinning of the colored adhesive tape and the thickness of the adhesive layer and the colored layer, the thickness of the substrate is preferably 9 μm or less, and more preferably 8.5 μm or less. In addition, the thickness of the substrate is not particularly limited as long as it has a strength capable of supporting the adhesive layer, etc., and can be, for example, 0.5 μm or more, 1.0 μm or more. More specifically, the thickness of the substrate is preferably 0.5 μm or more and 9 μm or less, more preferably 1.0 μm or more and 8.5 μm or less, even more preferably 1.5 μm or more and 6 μm or less, and particularly preferably 1.8 μm or more and 3 μm or less. By setting the thickness of the base material within the above range, the colored adhesive tape can be given the desired strength and flexibility, and even if the thickness of the colored adhesive tape is reduced to a predetermined value or less (especially 10 or so μm or less, particularly 10 μm or less), the adhesive layer and the colored layer can have a thickness that allows them to perform their respective functions. In this specification, "thickness" refers to the average thickness measured by a method conforming to JIS-Z-1702. In the case of a multi-layer structure, "thickness" refers to the total film thickness of each layer.

The substrate may be of a single layer structure or a multilayer structure. In particular, it is preferable that the substrate be of a single layer structure or a two-layer structure, since an extremely thin colored adhesive tape having a thickness of 10 μm or less, particularly 10 μm or less, can be obtained. This is because a substrate of a single layer structure or a two-layer structure can be easily adjusted to a thickness of 9 μm or less. In addition, in the manufacturing method of a resin film by multilayer extrusion of three or more layers, it is difficult to form a substrate with a total thickness of about several μm (10 μm or less).

The substrate preferably has the following structure [1a] or [2a]:
[1a] A single-layer structure having one layer in which the recycled resin content is 50% by mass or more and 100% by mass or less and the mechanical recycled resin content is 95% by mass or less. [2a] A two-layer structure having two of the above layers.

The reason why the substrate preferably has the structure of [1a] or [2a] is as follows. The mechanically recycled resin in the substrate contains impurities due to the recycling method, and the substrate contains more impurities as the content of the mechanically recycled resin increases. At this time, the amount of the impurities present in the outermost layer of the substrate causes defects in the adhesive layer and the colored layer in contact with the substrate. Specifically, the adhesive layer in contact with the substrate has defects caused by the impurities in the substrate, causing defects such as a decrease in adhesiveness and a poor appearance due to uneven adhesion. Similarly, the colored layer in contact with the substrate has defects caused by the impurities contained in the substrate, causing defects such as a poor appearance due to a decrease in design and light-shielding properties. In contrast, when the substrate has the above-mentioned single-layer or two-layer structure, the adhesive layer and the colored layer can suppress the occurrence of the above-mentioned defects caused by the impurities contained in the substrate. Among them, a single-layer structure is more preferable because it is easy to design the thickness of the substrate to a predetermined value or less, the colored adhesive tape can be made thinner, and the colored adhesive tape can be made to be more recyclable.

The layer having a recycled resin content of 50% by mass to 100% by mass and a mechanical recycled resin content of 95% by mass or less refers to a layer (resin film) having a recycled resin content of 50% by mass to 100% by mass and a mechanical recycled resin content of 95% by mass or less. Examples of such layers include, but are not limited to, the following layers L1 to L3.
Layer L1 in which the content of mechanically recycled resin in the layer is 50% by mass or more and 95% by mass or less
Layer L2 in which the content of chemically recycled resin in the layer is 50% by mass or more and 100% by mass or less
A layer L3 in which the content of mechanically recycled resin in the layer is less than 50% by mass, the content of chemically recycled resin in the layer is less than 50% by mass, and the sum of the contents of mechanically recycled resin and chemically recycled resin is 50% by mass or more.

The layer L1 may have a mechanically recycled resin content of 50% by mass or more and 95% by mass or less, and the content is preferably 60% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 95% by mass or less, and even more preferably 80% by mass or more and 90% by mass or less. Mechanically recycled resins have an excellent balance between quality and recycling costs, and can inexpensively increase the recycled raw material rate of adhesive tapes, but they contain impurities due to their recycling method. A layer (resin film) with a mechanically recycled resin content within the above range can suppress the occurrence of defects in the adhesive layer caused by the impurities even if it contains impurities, and can achieve a high recycled raw material rate. When the layer L1 contains two or more types of mechanically recycled resins, the content of the mechanically recycled resin refers to the sum of the contents of the two or more types. The resin constituting the layer L1 may contain chemically recycled resin and/or virgin resin in addition to mechanically recycled resin.

The layer L2 may have a chemically recycled resin content of 50% by mass or more and 100% by mass or less, and preferably has a content of 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. Since the chemically recycled resin is free of impurities generated by the regeneration method of the recycled resin or has only a small amount of impurities, by using a layer (resin film) having a chemically recycled resin content within the above range, defects in the adhesive layer caused by the impurities can be suppressed and a high recycled raw material rate can be achieved. When the layer L2 contains two or more types of chemically recycled resin, the content of the chemically recycled resin refers to the total content of the two or more types. The resin constituting the layer L2 may contain mechanically recycled resin and/or virgin resin in addition to the chemically recycled resin.

The layer L3 may have a mechanically recycled resin content of less than 50% by mass, a chemically recycled resin content of less than 50% by mass, and a total content of the mechanically recycled resin and the chemically recycled resin of 50% by mass or more. The content ratio of the mechanically recycled resin and the chemically recycled resin can be set appropriately. The resin constituting the layer L3 may contain virgin resin in addition to the mechanically recycled resin and the chemically recycled resin.

When the substrate has a single-layer structure, the substrate is preferably any one of the layers L1 to L3 described above. Among them, layer L1 or layer L2 is preferred, and layer L2 is even more preferred, because it is inexpensive and can achieve a high recycled material rate.

When the substrate has a two-layer structure consisting of a layer A1 and a layer A2 adjacent to the layer A1, the layers A1 and A2 are each selected from the group consisting of the layers L1 to L3, and the layers A1 and A2 may be the same or different. By having the two-layer substrate have the above-mentioned structure, defects due to impurities contained in the substrate are less likely to occur in both the adhesive layer and the colored layer that are in contact with the substrate.

In addition, when the above-mentioned substrate has a multi-layer structure of three or more layers, it is preferable that both outermost layers are layers having a recycled resin content of 50% by mass to 100% by mass and a mechanical recycled resin content of 95% by mass or less, or layers having a virgin resin content of 50% by mass or more, and layers other than the outermost layers of both of the substrates are layers having a mechanical recycled resin content of 50% by mass to 100% by mass. By having a substrate with a multi-layer structure of three or more layers have the above-mentioned structure, defects due to impurities contained in the substrate are less likely to occur in both the adhesive layer and the colored layer that are in contact with the substrate, and the substrate can be made inexpensive and have a high recycled material content.

The surface of the substrate may be untreated, or may be subjected to an easy-adhesion treatment to improve adhesion to the adhesive layer or colored layer. Examples of easy-adhesion treatments include physical treatments such as ultraviolet irradiation treatment, corona discharge treatment, plasma discharge treatment, and flame treatment; and chemical treatments such as alkali treatment and primer treatment.

The substrate may be stretched or unstretched. From the viewpoint of strength and transparency, a stretched film is preferable. The stretched film may be a uniaxially stretched film or a biaxially stretched film, but from the viewpoint of dimensional stability, a biaxially stretched film is preferable.

(3) Formation method The substrate can be formed by a conventionally known film forming method, and the method is not particularly limited, but can be produced, for example, by extrusion film formation by a T-die method. When the substrate has a multilayer structure, it can be produced by multilayer extrusion film formation by a T-die method. The method for producing the recycled polyester resin film used for the substrate can be, for example, the method disclosed in International Publication No. 2022/071440, JP 2021-172818 A, JP 2021-311668 A, etc.

2. Release Liner The release liner in the present invention contains a recycled resin and is provided on the surface of the pressure-sensitive adhesive layer, i.e., the surface of the pressure-sensitive adhesive layer opposite to the surface on the substrate side.

(1) Composition The release liner is made of resin, but may contain any other material such as additives in addition to the resin. A resin film can be used as the release liner. The content of the resin in the release liner is preferably 90% by mass or more and 100% by mass or less, more preferably 95% by mass or more and 100% by mass or less, and even more preferably 99% by mass or more and 100% by mass or less. When the release liner has a multi-layer structure of two or more layers, the content of the resin in the release liner refers to the proportion of the content of the resin in the total amount of the release liner having a multi-layer structure. The resin constituting the release liner includes at least recycled resin, but may also include virgin resin if necessary.

In order to make the recycled material ratio of the colored adhesive tape of the present invention equal to or greater than a predetermined value, it is preferable that the release liner contains a recycled resin as a main component. The content of the recycled resin in the release liner may be 50% by mass or more, and is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. The upper limit of the recycled resin ratio is most preferably 100% by mass, but the upper limit may be 99% by mass or 98% by mass. By setting the content of the recycled resin in the release liner within the above range, the recycled material ratio of the colored adhesive tape of the present invention can be further increased. When the recycled resin is a mixture of two or more types, the total content of the two or more types of recycled resin is referred to. When the release liner has a multilayer structure of two or more layers, the percentage of recycled resin in the release liner refers to the percentage of the recycled resin content in the total amount of the release liner, which is a multilayer structure.

The recycled resin constituting the release liner is not particularly limited, and the recycled resins exemplified in the above section "1. Substrate" can be used. The recycled resins may be used alone or in combination of two or more types. Among them, recycled polyester resins are preferred, and recycled polyethylene terephthalate (recycled PET) is more preferred, from the viewpoint of being recycled in large amounts and providing the strength and flexibility required of a release liner.

The recycled resin constituting the release liner is preferably at least one of chemically recycled resin and mechanically recycled resin, since a large amount of recycled resin can be obtained inexpensively by using a general-purpose recycling method. In particular, the chemically recycled resin and/or mechanically recycled resin is preferably a chemically recycled polyester resin and/or a mechanically recycled polyester resin among the recycled resins exemplified above, and is preferably chemically recycled polyethylene terephthalate (recycled PET) and/or mechanically recycled polyethylene terephthalate (recycled PET).

The recycled resin that constitutes the release liner is preferably a mechanically recycled resin, since it has an excellent balance between quality and recycling costs and can inexpensively increase the recycled raw material rate of the colored adhesive tape.

The recycled resin constituting the release liner is preferably a chemically recycled resin. Chemically recycled resin has less impurity contamination in the resin film due to the regeneration method of the recycled resin, and can suppress defects in the adhesive layer and colored layer caused by impurities contained in the release liner (resin film).

The recycled resin constituting the release liner may be a mixture of mechanically recycled resin and chemically recycled resin.

The release liner may contain a virgin resin in addition to the recycled resin. The virgin resin is not particularly limited, and examples thereof include the virgin resins exemplified in the above section "1. Substrate". In particular, the virgin resin is preferably the same type as the recycled resin, more preferably a polyester resin, and even more preferably a polyethylene terephthalate (PET) resin. Examples of polyester resins that can be used as virgin resins include the polyester resins exemplified in the above section "1. Substrate".

The release liner preferably contains a biomass material, and more preferably the recycled resin and/or virgin resin contained in the release liner contains raw materials derived from biomass. This is because the release liner can increase not only the recycled material rate but also the biomass content, resulting in a more environmentally friendly tape.

When the recycled resin and/or virgin resin constituting the release liner is a polyester resin, the polyester resin becomes a biomass polyester resin by containing a biomass-derived diol unit and/or a biomass-derived carboxylic acid unit. In particular, the polyester resin is preferably biomass polyethylene terephthalate.

The biomass degree of the release liner is preferably 1% by mass or more and 100% by mass or less, more preferably 50% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less. The recycle and biomass raw material ratios of the release liner are preferably 70% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less. When the release liner has a multi-layer structure, the biomass degree and the recycle and biomass raw material ratios are values for the entire multi-layer structure.

The release liner may contain various additives in addition to the resins described above. Specific examples of additives may be the same as those described in the "1. Substrate" section above.

(2) Properties The thickness of the release liner is not particularly limited as long as it can make the recycled material rate of the colored adhesive tape of the present invention equal to or higher than a predetermined value, and is preferably, for example, from 10 μm to 200 μm, more preferably from 12 μm to 100 μm, and even more preferably from 12 μm to 50 μm. When the release liner has a multi-layer structure, the thickness refers to the total thickness of each layer.

The release liner may have a single layer structure or a multilayer structure. In particular, the release liner preferably has the following structure [1b] or [2b].
[1b] A single-layer structure having a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanical recycled resin content of 95% by mass or less. [2b] A multilayer structure in which the outermost layer on the adhesive layer side is a layer having a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanical recycled resin content of 95% by mass or less, or a layer having a virgin resin content of 50% by mass or more. When the release liner has the structure [1b] or [2b] above, the occurrence of defects in the adhesive layer due to impurities contained in the layer that serves as the contact surface of the release liner with the adhesive layer can be suppressed, and a decrease in adhesiveness due to variations in adhesive strength can be suppressed.

The layer having a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanical recycled resin content of 95% by mass or less may be any layer (resin film) having a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanical recycled resin content of 95% by mass or less. Examples of such layers include the following layers M1 to M3.
Layer M1 in which the content of mechanically recycled resin in the layer is 50% by mass or more and 95% by mass or less
Layer M2 in which the content of chemically recycled resin in the layer is 50% by mass or more and 100% by mass or less
Layer M3 in which the content of mechanically recycled resin in the layer is less than 50% by mass, the content of chemically recycled resin in the layer is less than 50% by mass, and the sum of the contents of mechanically recycled resin and chemically recycled resin is 50% by mass or more.
Details of the layers M1, M2, and M3 are similar to those of the layers L1, L2, and L3 described in the section "1. Substrate (2) Properties" above, and therefore will not be described here.

When the release liner has a single-layer structure, it is preferable that the release liner is any one of the above-mentioned layers M1 to M3. Among them, layer M1 or layer M2 is preferable, and layer M2 is more preferable, because it is inexpensive and can achieve a high recycled material rate.

When the release liner has a multi-layer structure, at least one outermost layer (the outermost layer on the adhesive layer side) of the release liner may be a layer having a recycled resin content of 50% by mass to 100% by mass and a mechanical recycled resin content of 95% by mass or less, or a layer having a virgin resin content of 50% by mass or more. The multi-layer structure may be a two-layer structure, or a three-layer or more layer structure. The layers constituting the multi-layer release liner are referred to as layer B1, layer B2, layer B3, ... (omitted hereafter) from the adhesive layer side.

In the multi-layered release liner, the outermost layer on the adhesive layer side and the outermost layer on the opposite side to the adhesive layer side are preferably layers having a recycled resin content of 50% by mass to 100% by mass and a mechanical recycled resin content of 95% by mass or less, or layers having a virgin resin content of 50% by mass or more. The contact between the outermost layer on the adhesive layer side of the release liner and the adhesive layer, and the contact between the outermost layer on the opposite side to the adhesive layer side of the release liner and the colored layer when the colored adhesive tape is rolled, can suppress defects in the adhesive layer and colored layer caused by impurities contained in the release liner.

In the multi-layered release liner, it is preferable that the outermost layer on the pressure-sensitive adhesive layer side and the layer other than the outermost layer on the opposite side to the pressure-sensitive adhesive layer side are layers having a mechanically recycled resin content of 50% by mass to 100% by mass. By having both layers other than the outermost layer contain mechanically recycled resin as a main component, the recycled material rate of the entire release liner can be increased.

The release liner is preferably a three-layer structure having the layer B1, layer B2, and layer B3 in this order from the pressure-sensitive adhesive layer side. In the three-layer structure, the layer B1 and layer B3 are preferably layers having a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanical recycled resin content of 95% by mass or less, or layers having a virgin resin content of 50% by mass or more. In the three-layer structure, the layer B2 is preferably a layer having a mechanical recycled resin content of 50% by mass or more and 100% by mass or less. By making the release liner have such a three-layer structure, both the effects due to the outermost layer and the effects due to layers other than the outermost layer can be achieved. Examples of such a three-layer structure include the following configurations (layer B1/layer B2/layer B3), but are not limited to these configurations.
-Layer having a virgin resin content of 50% by mass or more/Layer having a mechanical recycled resin content of 50% by mass or more and 100% by mass or less/Layer having a virgin resin content of 50% by mass or more -Layer having a chemical recycled resin content of 50% by mass or more/Layer having a mechanical recycled resin content of 50% by mass or more and 100% by mass or less/Layer having a chemical recycled resin content of 50% by mass or more -Layer having a mechanical recycled resin content of 50% by mass or more and 95% by mass or less/Layer having a mechanical recycled resin content of 50% by mass or more and 100% by mass or less/Layer having a mechanical recycled resin content of 50% by mass or more and 95% by mass or less

The layers that make up the multilayer structure and have a mechanical recycled resin content of 50% by mass or more and 95% by mass or less, and the layers that have a chemical recycled resin content of 50% by mass or more and 100% by mass or less, can be similar to the layers M1 and M2 described above.

The layer that constitutes the multi-layer structure and has a mechanically recycled resin content of 50% by mass or more and 100% by mass or less may contain the largest amount of mechanically recycled resin, and the content is preferably 70% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass. This is because it is possible to achieve a low-cost and high recycled material rate.

The layer that constitutes the multi-layer structure and has a virgin resin content of 50% by mass or more and 100% by mass or less may contain the most virgin resin, and it is more preferable that the content is 70% by mass or more, even more preferable that the content is 90% by mass or more, and particularly preferable that the content is 100% by mass. This is because it is possible to achieve a low-cost and high recycled material rate.

In a release liner with a multi-layer structure, the thickness of the outermost layer is not particularly limited, but is preferably within the range of 1 μm to 100 μm, more preferably within the range of 3 μm to 75 μm, and even more preferably within the range of 5 μm to 50 μm.

In addition, in a release liner with a multi-layer structure, the thickness of the layers other than the outermost layer is not particularly limited, but is preferably in the range of 1 μm to 100 μm, more preferably in the range of 3 μm to 75 μm, and even more preferably in the range of 10 μm to 75 μm. In particular, when the layer other than the outermost layer has a mechanically recycled resin content of 50% by mass or more and 100% by mass or less, it is preferable to set the thickness of the layer within the above range, since this can increase the recycling rate at low cost.

The release liner has a laminated film or coating film containing a release agent on one side (the surface on the adhesive layer side) to provide easy peeling. Examples of the release agent that can be preferably used include silicone-based release agents, fluorine-based release agents, and long-chain alkyl-based release agents.

(3) Formation method The release liner can be formed by producing a resin film by the same method as the method for forming the substrate described in the above section "1. Substrate (3) Formation method" and performing a release treatment on the surface. When the release liner has a multilayer structure, a laminate of resin films is produced by multilayer extrusion film formation using a T-die method, and a release treatment is performed on the surface. The method for producing the recycled polyester resin film used in the release liner can be, for example, the method disclosed in WO 2022/071440, JP 2021-172818, JP 2021-311668, etc.

The release treatment applied to the surface of the release liner is not particularly limited, but examples include laminating or coating with various release agents used for release liners of pressure-sensitive adhesive tapes.

3. Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer in the present invention is provided on the surface of the substrate opposite to the colored layer side, and is composed of a pressure-sensitive adhesive.

(1) Composition The adhesive constituting the adhesive layer may be an adhesive made of conventional petroleum-derived raw materials (petroleum-based adhesive), an adhesive containing recycled raw materials (recycled adhesive), or an adhesive containing biomass-derived raw materials (biomass adhesive). Among these, an adhesive containing recycled raw materials is preferred from the viewpoint of environmental consideration, and an adhesive containing recycled raw materials and biomass-derived raw materials is more preferred.

The adhesive layer may or may not contain recycled materials, but it is preferable that the adhesive constituting the adhesive layer contains recycled materials, since the colored adhesive tape of the present invention can achieve a higher recycled material rate. The recycled material rate of the adhesive layer is preferably 1% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 100% by mass or less, and even more preferably 80% by mass or more and 100% by mass or less.

In addition, from the viewpoint of further increasing the biomass raw material ratio of the colored adhesive tape of the present invention, it is preferable that the adhesive constituting the adhesive layer is a biomass adhesive containing raw materials derived from biomass. The biomass degree of the adhesive layer is preferably 1% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 100% by mass or less, and even more preferably 80% by mass or more and 100% by mass or less. Since a more environmentally friendly colored adhesive tape can be obtained, the recycling and biomass raw material ratio of the adhesive layer is preferably 0% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less.

The recycled material rate, biomass degree, and recycled and biomass material rate of the adhesive layer can be adjusted as appropriate by selecting the type of monomer that constitutes the main component polymer (base polymer) contained in the adhesive layer and the type of tackifier resin that can be added to the adhesive layer.

The adhesive constituting the adhesive layer contains at least a polymer (base polymer) as a main component, and optionally contains a tackifier resin, a crosslinking agent, etc. Examples of such adhesives that can be used include acrylic adhesives whose main component is acrylic polymer, rubber adhesives whose main component is rubber polymer, polyester adhesives whose main component is polyester polymer, urethane adhesives whose main component is urethane polymer, vinyl alkyl ether adhesives, silicone adhesives, polyamide adhesives, fluorine adhesives, and epoxy adhesives. Only one type of adhesive may be used alone, or two or more types may be used in combination.

Among them, the adhesive constituting the adhesive layer is preferably an acrylic adhesive, a urethane adhesive, a rubber adhesive, or a polyester adhesive from the viewpoint of adhesion. Acrylic adhesives are preferred because they can exhibit higher adhesion in extremely thin colored adhesive tapes with a total thickness of a few μm. In addition, polyester adhesives are preferred because they can achieve a high recycled material rate and biomass degree, and because they can be returned to oligomers or monomers by depolymerization, making it easy to recycle the colored adhesive tape of the present invention itself.

(Acrylic polymer)
The acrylic polymer (acrylic polymer), which is the main component of the acrylic pressure-sensitive adhesive, is composed of (meth)acrylate alone or a copolymer of (meth)acrylate and other monomers. Examples of (meth)acrylate monomers used in the production of the acrylic polymer include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, cyclohexyl (meth)acrylate, and 2-ethylhexyl methacrylate, and one or more of these are used. Among them, (meth)acrylates having an alkyl group with 1 to 12 carbon atoms are preferred, and (meth)acrylates having an alkyl group with 4 to 8 carbon atoms are more preferred, and at least one of n-butyl acrylate and 2-ethylhexyl acrylate is preferred because it is easy to ensure adhesion to the adherend and has excellent cohesive force. The term "(meth)acrylate" is used to mean either acrylate or methacrylate.

The amount of the (meth)acrylate monomer contained in the total amount of monomers used to produce the acrylic polymer (in the structural units of the acrylic polymer) is preferably in the range of 80% by mass to 99% by mass, more preferably in the range of 85% by mass to 98.5% by mass, and more preferably in the range of 90% by mass to 97.5% by mass, since this makes it easier to ensure adhesion to the adherend and provides excellent cohesive strength. In addition, the (meth)acrylate monomer preferably contains 30% by mass or more of n-butyl acrylate, since this provides excellent adhesion and heat resistance.

The acrylic polymer contains a (meth)acrylate monomer as a constituent unit, but may further contain a highly polar vinyl monomer as a constituent unit. Examples of the highly polar vinyl monomer include vinyl monomers having a hydroxyl group, vinyl monomers having a carboxyl group, and vinyl monomers having an amide group, as well as other highly polar vinyl monomers other than these. Among these, it is preferable to contain one or more highly polar vinyl monomers selected from the group consisting of vinyl monomers having a hydroxyl group, vinyl monomers having a carboxyl group, and vinyl monomers having an amide group.

Examples of vinyl monomers having a hydroxyl group include hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate.

Examples of vinyl monomers having a carboxyl group that can be used include acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth)acrylic acid dimer, and crotonic acid, and among these, it is preferable to use acrylic acid.

Examples of vinyl monomers having an amide group include N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, and N,N-dimethylacrylamide.

Other highly polar vinyl monomers include those mentioned above, as well as vinyl acetate, ethylene oxide-modified succinic acid acrylate, and sulfonic acid group-containing monomers such as 2-acrylamido-2-methylpropanesulfonic acid.

The content of the highly polar vinyl monomer is preferably within the range of 1% by mass to 20% by mass, more preferably within the range of 2% by mass to 15% by mass, and even more preferably within the range of 2.5% by mass to 10% by mass, of the total amount of monomers constituting the acrylic polymer (of the constituent units of the acrylic polymer). By containing the highly polar vinyl monomer within the above range, it is easier to ensure adhesion to the adherend and it is more preferable because it has excellent cohesive force.

The molecular weight of the acrylic polymer is preferably in the range of 500,000 to 1,200,000, and more preferably in the range of 500,000 to 1,000,000, as calculated using standard polystyrene as measured by gel permeation chromatography (GPC). By having the weight average molecular weight (Mw) of the acrylic polymer in the above range, it is easy for the polymer to exhibit sufficient adhesiveness and heat resistance even in a thin film.

The weight average molecular weight of the acrylic polymer is a value measured by gel permeation chromatography (GPC) and calculated in terms of standard polystyrene. Specifically, the weight average molecular weight can be measured under the following conditions using a GPC device (HLC-8320GPC) manufactured by Tosoh Corporation.
Sample concentration: 1.0% by mass (tetrahydrofuran solution)
Sample injection volume: 100 μL
Eluent: tetrahydrofuran Flow rate: 0.8 mL/min Measurement temperature: 40° C.
Main column: TSKgel GMHHR-H(S) x 2 Guard column: TSKguardcolumn HHR(S)
Detector: Differential refractometer Weight average molecular weight of standard polystyrene: 10,000 to 20,000,000 (manufactured by Tosoh Corporation)

Acrylic polymers can be prepared by conventional polymerization methods such as solution polymerization, emulsion polymerization, and ultraviolet irradiation polymerization.

(Polyester Polymer)
The polyester polymer, which is the main component of the polyester-based pressure-sensitive adhesive, is a polymer of polymerization components including a polycarboxylic acid and a polyol, and has a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyol.

-Polycarboxylic acid-
The polycarboxylic acid-derived structural unit may be derived from petroleum or biomass, and may be derived from recycled materials.

Examples of polyvalent carboxylic acids forming the structural units derived from the above polyvalent carboxylic acids include divalent or trivalent or higher carboxylic acids. Examples of divalent carboxylic acids include aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, benzylmalonic acid, diphenic acid, 4,4'-oxydibenzoic acid, and naphthalenedicarboxylic acids (e.g., 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid); malonic acid, dimethylmalonic acid, succinic acid, methylsuccinic acid, glutaric acid, adipic acid, dimethyladipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, and 1,3 aliphatic dicarboxylic acids such as dimethylglutaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, thiodipropionic acid, diglycolic acid, 1,9-nonanedicarboxylic acid, dimer acid, and hydrogenated dimer acid; alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, and adamantanedicarboxylic acid; and the like. Examples of trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, adamantanetricarboxylic acid, and trimesic acid. These can be used alone or in combination of two or more kinds.

Among these, from the viewpoint of imparting a tacky feel, the polyester polymer preferably contains structural units derived from aliphatic dicarboxylic acids, and more preferably contains structural units derived from aliphatic dicarboxylic acids having 8 or less carbon atoms. Examples of the aliphatic dicarboxylic acids having 8 or less carbon atoms include linear aliphatic dicarboxylic acids such as malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and diglycolic acid having 8 or less carbon atoms; aliphatic dicarboxylic acids having side chain alkyl groups such as methylsuccinic acid, 2,2-dimethylglutaric acid, 1,3-dimethylglutaric acid, and dimethyladipic acid; sulfur-containing dicarboxylic acids such as thiodipropionic acid; and unsaturated group-containing aliphatic dicarboxylic acids such as fumaric acids, maleic acids, and itaconic acids. These may be contained alone or in combination of two or more.

The polyester polymer preferably contains structural units derived from linear aliphatic dicarboxylic acids, since they have excellent adhesion to various adherends and little change in adhesion initially and over time, and preferably contains structural units derived from adipic acids, since they exhibit excellent adhesion even in thin films and little change in adhesion over time. The content of the structural units derived from the aliphatic dicarboxylic acids having 8 or less carbon atoms is preferably 60 mol% or more and 100 mol% or less, more preferably 70 mol% or more and 100 mol% or less, and even more preferably 75 mol% or more and 98 mol% relative to the structural units derived from polyvalent carboxylic acids.

The polycarboxylic acid forming the structural unit derived from the polycarboxylic acid preferably contains an aromatic dicarboxylic acid in order to reduce the crystallinity of the polyester polymer, and more preferably contains an asymmetric aromatic dicarboxylic acid such as phthalic acid, isophthalic acid, 1,8-naphthalenedicarboxylic acid, or 2,3-naphthalenedicarboxylic acid. The content of the structural unit derived from the aromatic dicarboxylic acid is preferably 1 mol% to 40 mol%, and more preferably 2 mol% to 30 mol%, of the structural unit derived from the polycarboxylic acid in order to maintain high initial adhesive strength and tackiness.

-Polyol-
The polyol-derived structural unit may be derived from petroleum or biomass. The polyol-derived structural unit may be derived from recycling. The polyol constituting the polyol-derived structural unit includes dihydric or trihydric or higher polyols. These may be contained alone or in combination of two or more. Among them, it is preferable to contain a dihydric alcohol. Examples of the dihydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol, and dihydric alcohols derived from oleic acid, erucic acid, etc. aliphatic diols such as imidine diol and hydrogenated dimer diol; alicyclic diols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecane dimethanol, adamantanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; aromatic diols such as 4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-, m-, and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylenediol, and ethylene oxide adducts and propylene oxide adducts thereof; fatty acid esters derived from castor oil; and glycerol monostearate.

Among them, the polyol constituting the structural unit derived from the above polyol preferably contains at least one of an aliphatic diol and an alicyclic diol because of its excellent reactivity, and more preferably contains an aliphatic diol. The above aliphatic diol may be a straight-chain structure or may have a hydrocarbon group in the side chain, but an aliphatic diol with a straight-chain structure having 2 to 18 carbon atoms is preferred, and an aliphatic diol with 4 or less carbon atoms is preferred because of its high adhesive strength in a thin film. Specific examples include structural units derived from ethylene glycol, 1,3-propanediol, and 1,4-butanediol, and structural units derived from ethylene glycol are particularly preferred.

In terms of adhesive strength to various adherends and small changes in adhesive strength between the initial stage and over time, the polyol constituting the polyol-derived structural unit preferably contains at least one selected from the group consisting of ethylene glycol, 2-methyl-1,3-propanediol, and neopentyl glycol, and more preferably contains ethylene glycol and/or neopentyl glycol. The content of the at least one structural unit selected from the group consisting of ethylene glycol, 2-methyl-1,3-propanediol, and neopentyl glycol is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, relative to the polyol-derived structural unit. The upper limit is 100 mol%.

In order to increase the branching points in the polymer, the polyol constituting the structural units derived from the polyol may contain a polyhydric alcohol having a valence of three or more. Examples of the polyhydric alcohol having a valence of three or more include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, and adamantanetriol. The content of the structural units derived from the polyhydric alcohol having a valence of three or more is preferably 10 mol % or less, and particularly preferably 0.1 to 5 mol %, relative to the structural units derived from the polyol.

The proportions of structural units derived from each component of the polyester polymer (compositional proportions) can be determined by known methods using NMR, such as 1H-NMR measurement (proton-type nuclear magnetic resonance spectroscopy) at a resonance frequency of 400 MHz, 13C-NMR measurement (carbon-type nuclear magnetic resonance spectroscopy), etc. The proportions of structural units derived from each component of the polyester polymer can be calculated from the blending ratios in a composition containing polyol and polycarboxylic acid when preparing the polyester polymer.

In addition to structural units derived from polyvalent carboxylic acids and structural units derived from polyols, polyester polymers may also have structural units derived from compounds that have both carboxylic acids and hydroxyl groups in the molecule (e.g., lactic acid, etc.).

The blend ratio of the polycarboxylic acid and polyol when preparing the polyester polymer is preferably 1 to 2 equivalents of polyol per equivalent of polycarboxylic acid, more preferably 1.1 to 1.7 equivalents.

Polyester polymers can be produced, for example, by polycondensation reaction of polycarboxylic acid and polyol in the presence of a catalyst by a known method. Since polyester polymers are obtained by polycondensation reaction of polycarboxylic acid and polyol, they have structural units derived from polycarboxylic acid and structural units derived from polyol. In the above polycondensation reaction, an esterification reaction or an ester exchange reaction is carried out first, and then the polycondensation reaction is carried out. However, if it is not necessary to produce a high molecular weight, it may be produced by only esterification reaction or ester exchange reaction.

(Tackifier resin)
The above-mentioned adhesive may contain one or more tackifier resins in order to improve the adhesiveness of the adhesive layer, in addition to the base polymer, which is the main component. The tackifier resin is not particularly limited, and conventionally known materials can be used, for example, hydrocarbon-based tackifier resins, terpene-based resins, phenol-based resins, rosin-based resins, xylene resins, epoxy-based resins, polyamide-based resins, ketone-based resins, elastomer-based resins, etc. are listed. Among them, from the viewpoint of exhibiting a thin and excellent adhesiveness, rosin-based resins, hydrocarbon-based tackifier resins, terpene-based resins, etc. are preferred. When the adhesive is an acrylic adhesive, rosin-based resins are particularly preferred. Furthermore, when the adhesive is a polyester adhesive, hydrocarbon-based tackifier resins are preferred.

The above-mentioned rosin-based resins include, for example, rosin resin, polymerized rosin resin, hydrogenated rosin resin, rosin ester resin, hydrogenated rosin ester resin, rosin phenolic resin, polymerized rosin ester, etc., and specifically include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin, modified rosins that have been hydrogenated, disproportionated, polymerized, or otherwise chemically modified, and derivatives of these.

Examples of the above-mentioned hydrocarbon-based tackifying resins include various hydrocarbon-based resins such as aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic/aromatic petroleum resins (styrene-olefin copolymers, etc.), aliphatic/alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, and coumarone-indene resins.

The tackifier resin may be derived from petroleum or biomass. In particular, by using a tackifier resin derived from biomass, the biomass content of the adhesive layer can be increased. Examples of tackifier resins derived from biomass include rosin resin and terpene resin. The biomass content of the tackifier resin is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and most preferably 95% to 100% by mass.

The softening point of the tackifier resin, as measured by the ring and ball method, is preferably within the range of 80°C to 170°C, more preferably within the range of 90°C to 160°C, more preferably within the range of 100°C to 150°C, and even more preferably within the range of 100°C to 135°C. By setting the softening point of the tackifier resin within the above range, it is possible to increase the adhesion and cohesive strength even in a thin adhesive layer.

The amount of the tackifier resin can be appropriately selected depending on the type of base polymer that is the main component of the adhesive, but for example, it can be in the range of 0 to 60 parts by mass per 100 parts by mass of the base polymer that is the main component of the adhesive, preferably in the range of 5 to 55 parts by mass, more preferably in the range of 10 to 50 parts by mass, and even more preferably in the range of 20 to 45 parts by mass from the viewpoint of further enhancing adhesion.

(Crosslinking Agent)
The pressure-sensitive adhesive may contain a crosslinking agent to increase the cohesive strength of the pressure-sensitive adhesive layer. The crosslinking agent may be, for example, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a metal chelate-based crosslinking agent, an aziridine-based crosslinking agent, or the like, which may be used alone or in combination of two or more. Among these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents, which are highly reactive with the resin that is the main component of the pressure-sensitive adhesive, are preferred, and isocyanate-based crosslinking agents are more preferred.

It is preferable that the isocyanate-based crosslinking agent has at least two or more isocyanate groups in the molecule, and more preferably, there is no particular limitation as long as it has three or more. Examples of such polyfunctional isocyanate-based crosslinking agents include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates. Specific compounds of aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates can be, for example, compounds exemplified in various polyisocyanates disclosed in WO 2021/117826 and WO 2021/153390.

In addition to aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates, dimers and trimers of aromatic aliphatic polyisocyanates can be used as the polyfunctional isocyanate compound. Specific examples include dimers and trimers of diphenylmethane diisocyanate, reaction products of trimethylolpropane and tolylene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, and polymers such as polymethylene polyphenylisocyanate, polyether polyisocyanate, and polyester polyisocyanate. Preferably, an adduct of tolylene diisocyanate and trimethylolpropane can be used.

Commercially available products can also be used as polyfunctional isocyanate crosslinking agents. Specific examples include a trimer adduct of trimethylolpropane and tolylene diisocyanate under the trade name "Burnoc D-40" (manufactured by DIC Corporation) and a trimer adduct of trimethylolpropane and hexamethylene diisocyanate under the trade name "Coronate HL" (manufactured by Nippon Polyurethane Industry Co., Ltd.).

The amount of crosslinking agent can be appropriately set depending on the gel fraction of the adhesive layer, which will be described later.

(Additive)
The pressure sensitive adhesive may contain any additives as necessary. Examples of the additives include viscosity adjusters (thickeners, etc.), leveling agents, release adjusters, plasticizers, softeners, fillers such as glass or plastic fibers, balloons, beads, metal powders, etc., conductive materials, colorants (pigments, dyes, etc.), surfactants, antistatic agents, preservatives, antioxidants, UV absorbers, antioxidants, light stabilizers, hydrolysis inhibitors, crosslinking catalysts, retarders, silane coupling agents, surface lubricants, polymerization inhibitors, water repellents, and defoamers.

(2) Properties In order to exhibit suitable adhesive strength while being a thin colored adhesive tape, the thickness of the adhesive layer can be 1 μm or more, preferably 1.5 μm or more, more preferably 2 μm or more, and the thickness can be 12 μm or less, preferably 9 μm or less, more preferably 4 μm or less. Specifically, the thickness of the adhesive layer is preferably 1 μm or more and 12 μm or less, more preferably 1 μm or more and 9 μm or less, more preferably 2 μm or more and 9 μm or less, and even more preferably 2 μm or more and 4 μm or less.

The gel fraction of the adhesive layer is not particularly limited, but from the viewpoint of achieving both good adhesion and durability, it can be in the range of 5% by mass to 80% by mass, preferably in the range of 10% by mass to 70% by mass, more preferably in the range of 15% by mass to 65% by mass, even more preferably in the range of 20% by mass to 50% by mass, and even more preferably in the range of 30% by mass to 45% by mass. When the adhesive layer is made of an acrylic adhesive, the gel fraction of the adhesive layer is preferably in the range of 5% by mass to 50% by mass, more preferably in the range of 10% by mass to 40% by mass, and even more preferably in the range of 15% by mass to 35% by mass. When the adhesive layer is made of a polyester adhesive, the gel fraction of the adhesive layer is preferably in the range of 15% by mass to 80% by mass, more preferably in the range of 20% by mass to 70% by mass, even more preferably in the range of 30% by mass to 55% by mass, and even more preferably in the range of 35% by mass to 45% by mass.

The gel fraction is a value expressed as a percentage of the original mass, obtained by immersing the pressure-sensitive adhesive layer after curing in toluene and leaving it for 24 hours, and measuring the mass of the remaining insoluble matter after drying.
Gel fraction [mass %]=[(mass of pressure-sensitive adhesive layer after immersion in toluene)/(mass of pressure-sensitive adhesive layer before immersion in toluene)]×100

(3) Formation method The adhesive layer can be formed by a known method, for example, by applying an adhesive composition containing the above-mentioned adhesive and, if necessary, a solvent to one side of a substrate or one side of a release liner, drying the adhesive composition, and curing the adhesive composition if necessary. For example, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, etc. can be used as a method for applying the adhesive composition.

The drying conditions for the coating of the pressure-sensitive adhesive composition are not particularly limited, but the drying temperature is preferably 60 to 140°C, more preferably 80 to 120°C. The drying time is preferably 0.5 to 30 minutes, more preferably 1 to 5 minutes. The conditions for the curing treatment can be set appropriately, but it is preferably room temperature (23°C) to 70°C for 1 to 30 days, more preferably 23°C for 1 to 20 days, more preferably 23°C for 3 to 14 days, and even more preferably 40°C for 1 to 10 days.

4. Colored Layer The colored layer in the present invention is provided on the surface of the substrate opposite to the surface on which the pressure-sensitive adhesive layer is formed. The colored layer is a layer that imparts design properties and shielding properties to the colored pressure-sensitive adhesive tape.

(1) Composition The colored layer includes a resin and a coloring material. The resin and/or the coloring material may or may not include recycled materials, but from the viewpoint of environmental consideration, it is preferable that the resin and/or the coloring material includes recycled materials, and it is more preferable that the resin and/or the coloring material includes recycled materials and materials derived from biomass.

The recycled material ratio of the colored layer is not particularly limited, but is preferably 1% by mass or more and 100% by mass or less, more preferably 30% by mass or more and 100% by mass or less, and even more preferably 50% by mass or more and 100% by mass or less. By having the colored layer exhibit a recycled material ratio within the above range, a more environmentally friendly colored adhesive tape can be obtained. The biomass degree of the colored layer is also not particularly limited, but is preferably 1% by mass or more and 100% by mass or less, more preferably 30% by mass or more and 50% by mass or less, and even more preferably 50% by mass or more and 100% by mass or less. Furthermore, the recycled and biomass raw material ratios of the colored layer are preferably 1% by mass or more and 100% by mass or less, more preferably 50% by mass or more and 100% by mass or less, and even more preferably 70% by mass or more and 100% by mass or less. By having the colored layer exhibit a biomass degree and/or recycled and biomass raw material ratio within the above range, a more environmentally friendly colored adhesive tape can be obtained.

(resin)
The content of the resin constituting the colored layer is preferably in the range of 30% by mass to 90% by mass, more preferably in the range of 40% by mass to 80% by mass, and even more preferably in the range of 50% by mass to 65% by mass, based on the total amount of the colored layer. By setting the content of the resin in the colored layer within the above range, the glass transition temperature of the colored layer can be adjusted within a predetermined range, and the colored layer can exhibit excellent alcohol resistance. When the colored layer is composed of two or more types of resin, it is preferable that the total content is within the above range.

Examples of resins constituting the colored layer include urethane resins, epoxy resins, polyester resins, polyester urethane resins, acrylic resins, etc., which are used in general-purpose inks. Among them, it is preferable that the resin is a cured product of a resin composition containing a polyol component mainly composed of polyester polyol and an isocyanate component mainly composed of a polyfunctional isocyanate (cured product of polyester resin). This is because the colored adhesive tape having a colored layer on its surface can achieve good alcohol resistance, curl resistance, and interlayer adhesion, and in particular good adhesion to recycled polyester films. The cured product of the polyester resin has structural units derived from polyester polyol and structural units derived from polyfunctional isocyanate.

-Polyol component-
The polyol component forming the cured product of the polyester resin is mainly composed of a polyester polyol. The polyester polyol is a compound having two or more hydroxyl groups. Examples of such polyester polyols include polyester polyols obtained by reacting one or more polyvalent carboxylic acids with one or more polyhydric alcohols, polyester polyols obtained by ring-opening polymerization of cyclic ester compounds such as ε-caprolactone, and polyester polyols obtained by copolymerizing these.

Any known raw material can be used as the polyvalent carboxylic acid for preparing the polyester polyol. Examples of the polyvalent carboxylic acid include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, and other dicarboxylic acids and anhydrides or ester-forming derivatives of these dicarboxylic acids; p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids, and dimer acid, which can be used alone or in a mixture of two or more kinds. The dimer acids mentioned above are products of Diels-Alder dimerization of C18 unsaturated fatty acids such as oleic acid and linoleic acid, and various types are commercially available, including those saturated by adding hydrogen to the unsaturated bonds. A typical example is one that consists of 0-5% by mass of C18 monocarboxylic acid, 70-98% by mass of C36 dimer acid, and 0-30% by mass of C54 trimer acid.

The polycarboxylic acid is preferably derived from recycled materials, since it increases the recycled material ratio of the colored layer. The polycarboxylic acid may be derived from petroleum, but is preferably derived from biomass, since it increases the biomass content of the colored layer.

Any of the known raw materials can be used as the polyhydric alcohol for preparing the polyester polyol. Specific examples of polyols include glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, triethylene glycol, polycaprolactone diol, dimer diol, hydrogenated dimer diol, bisphenol A, and hydrogenated bisphenol A. Polyols such as olefins; polyesters obtained by ring-opening polymerization of cyclic ester compounds such as propiolactone, butyrolactone, ε-caprolactone, δ-valerolactone, and β-methyl-δ-valerolactone; and polyethers obtained by addition polymerization of one or more compounds having two active hydrogen atoms, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol, with one or more monomers, such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, and cyclohexylene, by a conventional method. These various polyols can be used alone or as a mixture of two or more.

The polyhydric alcohol is preferably derived from recycled materials, as this increases the recycled material ratio of the colored layer. The polyhydric alcohol may be derived from petroleum, but is preferably derived from biomass, as this increases the biomass content of the colored layer.

The polyester polyol preferably has a weight average molecular weight in the range of 1,000 to 400,000. If the weight average molecular weight of the polyester polyol is 1,000 or more, the printability, coating suitability, and alcohol resistance of the polyester polyol tend to be favorable, and if it is 40,0000 or less, the drying property and blocking resistance tend to be improved. The weight average molecular weight of the polyester polyol is further preferably in the range of 2,000 to 350,000, and more preferably in the range of 3,000 to 300,000.

The weight average molecular weight of the polyester polyol is calculated as standard polystyrene by gel permeation chromatography (GPC). The measurement conditions are as follows: TSKgel GMHXL [manufactured by Tosoh] is used as the column, the column temperature is 40°C, the eluent is tetrahydrofuran, the flow rate is 1.0 mL/min, and the standard polystyrene is TSK standard polystyrene.

The polyol component constituting the cured polyester resin may contain only the above-mentioned polyester polyol, or may contain, in addition to the polyester polyol, one or more polyols other than the polyester polyol, as long as it is possible to set the glass transition temperature of the colored layer within a predetermined range.

- Isocyanate component -
The isocyanate component constituting the cured product of the polyester resin is a component that reacts with the polyol component described above, and is mainly composed of a polyfunctional isocyanate. The polyfunctional isocyanate may be one having two or more isocyanate groups in one molecule, and among them, a diisocyanate having two isocyanate groups can be preferably used. Examples of the diisocyanate include aromatic diisocyanates (diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, tolylene diisocyanate, prepolymers of low molecular weight glycols and the above aromatic diisocyanates, etc.), aliphatic diisocyanates (1,6-hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, low molecular weight glycols such as ethylene glycol and propylene glycol and the above aliphatic diisocyanates, etc.), and the like. Examples of suitable diisocyanates include aliphatic or alicyclic diisocyanates (isophorone diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, methylcyclohexylene diisocyanate, isopropylidenedicyclohexyl-4,4'-diisocyanate, prepolymers of low molecular weight glycols and the above-mentioned alicyclic diisocyanates, etc.) and mixtures of two or more of these, adducts of the above-mentioned diisocyanates and polyols, and isocyanurates, biurets, and allophanates of the above-mentioned diisocyanates. Among these, aliphatic or alicyclic diisocyanates, and their adducts, isocyanurates, biurets, and allophanates are less likely to curl due to shrinkage upon curing and are therefore suitable for use in thin films.

The isocyanate component may contain one type of polyfunctional isocyanate, or may contain two or more types of polyfunctional isocyanates. In addition, the isocyanate component may contain other isocyanates as long as it contains a polyfunctional isocyanate as the main component, and may contain other isocyanates as long as it is possible to set the glass transition temperature of the colored layer within a predetermined range.

- Cured polyester resin -
The glass transition temperature of the cured product of the polyester resin can be realized by appropriately combining the blending ratio of the polyol component and the isocyanate component described above. The blending ratio of the polyol component mainly composed of polyester polyol and the isocyanate component mainly composed of polyfunctional isocyanate can be appropriately set according to the hydroxyl value of the polyester polyol, which is the main component of the base agent, and the number of isocyanate groups of the polyfunctional isocyanate. For example, it is preferable to blend so that the ratio of the hydroxyl group of the polyol component to the isocyanate group of the isocyanate component (hydroxyl group/isocyanate group) is 1/0.5 to 1/10 (equivalent ratio), and more preferably 1/0.6 to 1/5.

The cured product of the polyester resin is preferably a cured product of a recycled polyester resin. This is because the recycled raw material rate of the colored layer and the colored adhesive tape can be further increased. The cured product of the recycled polyester resin can be obtained by containing a recycled material in at least one of the polyester polyol and the crosslinking agent. In particular, it is preferable that the polyvalent carboxylic acid and/or polyhydric alcohol constituting the polyester polyol are derived from a recycled material.

(Coloring materials)
The coloring material may be a known pigment or dye, and may be appropriately selected according to the color of the colored layer. For example, carbon black is preferred for black, titanium oxide, calcium carbonate, or barium sulfate is preferred for white, yellow iron oxide is preferred for yellow, red iron oxide is preferred for red, cyanine blue is preferred for blue, aluminum powder is preferred for silver, and titanium mica powder is preferred for pearl, due to their weather resistance, heat resistance, and dispersibility in ink resin. Among these, carbon black is preferred because of its excellent hiding power. It is also preferred that the coloring material does not contain halogen.

The content of the coloring material in the colored layer may be adjusted as appropriate depending on the application, etc., and is preferably 10 to 70% by mass in the colored layer, more preferably 20 to 60% by mass, and even more preferably 35 to 50% by mass. By making the amount of the coloring material 10% by mass or more, the colored adhesive tape of the present invention can exhibit favorable design properties and shielding properties, while by making the amount of the coloring material 70% by mass or less, the dispersibility of the coloring material in the colored layer is good.

(any material)
The colored layer may contain various other additives as necessary, such as an antiaging agent, a light stabilizer, an antiblocking agent, a dispersant, an antisettling agent, a filler, and a wax.

(2) Properties The colored layer preferably has a glass transition temperature in the range of 45° C. to 65° C., more preferably in the range of 48° C. to 62° C., and particularly preferably in the range of 50° C. to 60° C. When the colored layer has a glass transition temperature in the above range, it can exhibit excellent alcohol resistance.

The glass transition temperature is a value measured by performing measurements using DSC in accordance with ISO 3146. The glass transition temperature of the colored layer is largely influenced by the glass transition temperature of the resin contained in the colored layer, and therefore can be adjusted mainly by the glass transition temperature of the resin contained in the colored layer. For example, when the resin contained in the colored layer is a cured product of a resin composition containing a polyol component mainly composed of polyester polyol and an isocyanate component mainly composed of polyfunctional isocyanate (cured product of polyester resin), it can be realized by appropriately combining the compounding ratio of the polyol component and the isocyanate component.

The colored layer can be appropriately set within a range in which the total thickness of the colored adhesive tape excluding the release liner is equal to or less than a predetermined value, but is preferably 0.5 μm to 5 μm, more preferably 0.55 μm to 5 μm, more preferably 1 μm to 4 μm, even more preferably 1.5 μm to 3.5 μm, and particularly preferably 2.0 μm to 3.0 μm. By having the thickness of the colored layer within the above range, it is possible to achieve suitable design and adhesion to the substrate, as well as a thin colored layer and curl resistance.

The pencil hardness of the colored layer is preferably HB to 2H. More preferably, it is F to H. A hardness of HB or higher can provide suitable alcohol resistance, while a hardness of 2H or lower can provide suitable curl resistance and adhesion to the substrate. The hardness of the colored layer can be measured based on the scratch hardness (pencil method) of JIS K5600.

(3) Formation method The colored layer can be formed using a colored ink containing at least a resin and a coloring material. When the resin contained in the colored layer is a cured product of a resin composition containing a polyol component mainly composed of polyester polyol and an isocyanate component mainly composed of polyfunctional isocyanate (cured product of polyester resin), the colored layer can be formed using a colored ink containing a two-component curing resin containing a polyol component mainly composed of polyester polyol as a main component and an isocyanate component mainly composed of polyfunctional isocyanate as a curing agent, and a colored material.

The colored layer is preferably provided by printing a colored ink on the substrate by a known printing method. Examples of printing methods include direct gravure printing, reverse gravure printing, and small-diameter gravure printing. Direct gravure printing is preferred because it is less likely to tear even on thin substrates and has excellent printability. The colored ink usually contains a solvent. Examples of the solvent include solvents known as solvents for printing inks.

5. Matte Layer The colored adhesive tape of the present invention may have a matte layer on the surface of the colored layer. The matte layer is usually disposed directly on the surface of the colored layer without any other layer therebetween.

The matte layer contains a resin and fine particles. Examples of the fine particles include general-purpose fine particles such as silica, calcium carbonate, and barium sulfate. Among these, silica particles are preferred. The resin contained in the matte layer can be appropriately selected from general-purpose resins, and examples of the resin include urethane resins and polyester resins. Among these, from the viewpoint of improving the curl resistance and alcohol resistance of the matte layer, it is preferred to use a cured product of the polyester resin described in the above section "4. Colored layer."

The recycled material rate, biomass degree, and recycled and biomass material rate of the matte layer are preferably within the ranges of the recycled material rate, biomass degree, and recycled and biomass material rate described in Section 4. Colored Layer above. This is because it allows for a more environmentally friendly colored adhesive tape.

The matte layer preferably has a glass transition temperature of 45 to 65°C, more preferably 48 to 62°C, and even more preferably 50 to 60°C. By setting the glass transition temperature of the matte layer within the above range, even a colored film provided with a matte layer can exhibit curl resistance and alcohol resistance. The glass transition temperature of the matte layer can be measured by measuring using a DSC in accordance with ISO 3146.

The thickness of the matte layer is not particularly limited as long as it is large enough to exhibit the desired function, and is preferably, for example, 0.3 μm to 3 μm, more preferably 0.4 μm to 2 μm, and even more preferably 0.5 μm to 1.5 μm.

The matte layer can be formed by applying a known surface treatment agent containing a matte agent (i.e., a matte agent) in which fine particles are dispersed in a resin to the surface of the colored layer (i.e., the surface of the colored layer opposite the surface facing the substrate).

6. Manufacturing Method The manufacturing method of the colored pressure-sensitive adhesive tape of the present invention is not particularly limited, and any known method can be used. Among them, the manufacturing methods of the first to fourth embodiments described below can be preferably used. The details of the release liner, substrate, colored layer, and pressure-sensitive adhesive layer used or formed in each step, and the method of formation are as already described.

(First aspect)
A first aspect of the method for producing a colored adhesive tape of the present invention is a production method comprising a colored layer forming step of forming a colored layer on one side of a substrate containing a recycled resin, an adhesive layer forming step of applying an adhesive to the other side of the substrate to form an adhesive layer, and a laminating step of laminating a release liner containing a recycled resin to the surface of the adhesive layer. Note that in the laminating step, the release-treated surface of the release liner is laminated to the adhesive layer.

In the manufacturing method of the first aspect, the base material preferably has the following structure [1a] or [2a]:
[1a] A single-layer structure having one layer with a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanical recycled resin content of 95% by mass or less [2a] A two-layer structure having two of the above layers By the substrate having the structure [1a] or [2a] above, the proportion of recycled raw materials in the colored adhesive tape can be made to be a predetermined value or more. In addition, when the colored layer and the adhesive layer are formed in the colored layer forming step and the adhesive layer forming step, defects in the colored layer and the adhesive layer due to impurities contained in the substrate can be suppressed.

In addition, in the manufacturing method of the first aspect, the thickness of the substrate is preferably 9 μm or less. This is because the total thickness of the colored adhesive tape excluding the release liner can be easily adjusted to a predetermined range.

In the production method of the first aspect, the release liner preferably has the following structure [1b] or [2b]:
[1b] A single-layer structure containing 50% by mass or more and 100% by mass or less of recycled resin and 95% by mass or less of mechanically recycled resin [2b] A multi-layer structure in which at least one outermost layer is a layer containing 50% by mass or more and 100% by mass or less of recycled resin and 95% by mass or less of mechanically recycled resin, or a layer containing 50% by mass or more of virgin resin In this case, in the lamination step, it is preferable to laminate the surface of the pressure-sensitive adhesive layer to one side of the release liner having a single layer structure or the surface of one of the outermost layers of the release liner having a multi-layer structure. This is because the occurrence of defects in the pressure-sensitive adhesive layer due to impurities contained in the release liner can be suppressed when the release liner is laminated to the surface of the pressure-sensitive adhesive layer in the lamination step.

(Second Aspect)
A second embodiment of the method for producing a colored adhesive tape of the present invention is a production method comprising an adhesive layer forming step of applying an adhesive to a release liner containing a recycled resin to form an adhesive layer to obtain a release liner with an adhesive layer, a colored layer forming step of forming a colored layer on one side of a substrate containing a recycled resin, and a lamination step of laminating the adhesive layer side of the release liner with the adhesive layer to the other side of the substrate. Note that in the adhesive layer forming step, the adhesive layer is usually formed on the release treated surface of the release liner.

In the manufacturing method of the second aspect, the release liner preferably has the structure of [1b] or [2b] described in the manufacturing method of the first aspect. In this case, in the adhesive layer forming step, an adhesive is preferably applied to one side of the release liner having a single layer structure or to the surface of one of the outermost layers of the release liner having a multilayer structure to form an adhesive layer. This is because, when an adhesive layer is formed on the surface of the release liner in the adhesive layer forming step, defects in the adhesive layer due to impurities contained in the release liner can be suppressed.

In the manufacturing method of the second aspect, the substrate preferably has the structure of [1a] or [2a] described in the manufacturing method of the first aspect. This is because the proportion of recycled raw materials in the colored adhesive tape can be set to a predetermined value or more, and defects in the colored layer or adhesive layer caused by impurities contained in the substrate can be suppressed when forming the colored layer or laminating the adhesive layer in the colored layer forming step or laminating step. In addition, in the manufacturing method of the second aspect, the thickness of the substrate is preferably 9 μm or less. The reason for this is the same as that described in the manufacturing method of the first aspect.

(Third aspect)
A third aspect of the method for producing a colored adhesive tape of the present invention is a production method comprising an adhesive layer forming step of applying an adhesive to one side of a substrate containing a recycled resin to form an adhesive layer, a laminating step of laminating a release liner containing a recycled resin to the surface of the adhesive layer, and a colored layer forming step of forming a colored layer on the other side of the substrate. In the laminating step, the release treated surface of the release liner is laminated to the adhesive layer.

In the manufacturing method of the third aspect, the substrate preferably has the structure of [1a] or [2a] described in the manufacturing method of the first aspect. The reason for this is the same as that described in the manufacturing method of the first aspect. In addition, in the manufacturing method of the third aspect, the thickness of the substrate is preferably 9 μm or less. The reason for this is the same as that described in the manufacturing method of the first aspect.

In the manufacturing method of the third aspect, the release liner preferably has the structure [1b] or [2b] described in the manufacturing method of the first aspect. In this case, in the laminating step, it is preferable to laminate one side of the release liner having a single layer structure or the surface of one of the outermost layers of the release liner having a multilayer structure to the surface of the pressure-sensitive adhesive layer. The reason for this is the same as that described in the manufacturing method of the first aspect.

(Fourth aspect)
A fourth aspect of the method for producing a colored adhesive tape of the present invention is a production method comprising an adhesive layer forming step of applying an adhesive to a release liner containing a recycled resin to form an adhesive layer to obtain a release liner with an adhesive layer, a laminating step of laminating a substrate containing a recycled resin to the surface of the adhesive layer of the release liner with an adhesive layer, and a colored layer forming step of forming a colored layer on the surface of the substrate. Note that in the adhesive layer forming step, the adhesive layer is formed on the release-treated surface of the release liner.

In the manufacturing method of the fourth aspect, the substrate preferably has the structure [1a] or [2a] described in the manufacturing method of the first aspect. The reason for this is the same as that described in the manufacturing method of the second aspect. In addition, in the manufacturing method of the fourth aspect, the thickness of the substrate is preferably 9 μm or less. The reason for this is the same as that described in the manufacturing method of the first aspect.

In the manufacturing method of the fourth aspect, the release liner preferably has the structure of [1b] or [2b] described in the manufacturing method of the first aspect. In this case, in the pressure-sensitive adhesive layer forming step, the pressure-sensitive adhesive layer is preferably formed on one side of the release liner having a single layer structure, or on the surface of one of the outermost layers of the release liner having a multilayer structure. The reason for this is the same as that described in the manufacturing method of the second aspect.

7. Applications The applications of the colored adhesive tape of the present invention are not particularly limited, but since the tape has a high recycled material ratio as a whole, is thin and exhibits excellent adhesive strength, designability, and shielding properties, it can be used particularly effectively in portable electronic devices, which are becoming thinner and using more recycled materials. Specific examples of applications include the insulation, protection, and fixing of various components in portable electronic devices, such as electronic organizers, mobile phones, smartphones, tablet terminals, PHS, cameras, and music players.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

1. Pellet production (recycled pellet A)
The release film, which was a polyester film coated with silicone, was cut into 1 cm x 1 cm pieces to make chips. About 10 kg of the chips were placed in a treatment vessel, and then 2.0 g of a hot aqueous solution of caustic soda set to 0.7% by mass and a polyethylene glycol ether of higher alcohol (Emulgen 106, manufactured by Kao Corporation) were added together, followed by stirring at 105°C for 15 minutes at a rotation speed of about 100 rpm. After stirring, the treatment liquid was discharged and the liquid was thoroughly drained, and then water washing treatment was performed for 10 minutes.
Then, 10.0 g of a 1% by mass hot aqueous solution of caustic soda and a polyethylene glycol ether of a higher alcohol were added to the first caustic alkali-treated chip sample, and the chip sample was stirred at about 200 rpm for 40 minutes at 120° C. After stirring, the treatment solution was drained and the mixture was thoroughly drained, and then the mixture was washed with plenty of running water for 15 minutes to remove foreign matter.
The washed chips were then removed and dried at 100° C. for 60 minutes. The dried chips were further vacuum-dried and then heated and melted at 280° C. to form a polyester film, which was then cut to obtain mechanically recycled polyester pellets (recycled pellets A). The recycled material rate of the recycled pellets A was 100%.

(Recycled pellets B)
A stirrer equipped with two 45° paddle blades was installed in the depolymerization tank. The upper 45° paddle blade was set at a depth of 20 mm from the liquid level of the depolymerization liquid. The lower 45° paddle blade was set at a position of 500 mm from the liquid level. A release film obtained by coating a polyester film with silicone was cut into 20 mm squares, and 100 parts by mass of the cut film, 400 parts by mass of ethylene glycol, and 3 parts by mass of sodium carbonate as a depolymerization catalyst were charged into the depolymerization tank. Next, the temperature was raised to 190° C. while stirring with the stirrer of the depolymerization tank at 50 rpm, and the mixture was maintained for 1 hour. As a result, a part of the polyethylene terephthalate was depolymerized, and floating of a thin film-like release agent was confirmed. Then, 0.04 parts by mass of ethyl acid phosphate was added to this reaction mixture, followed by the addition of 0.5 parts by mass of spherical organic crosslinked particles having an average particle size of 1.1 μm and 0.03 parts by mass of antimony trioxide, and the mixture was maintained at 190° C. for 4 hours, at which time the depolymerization reaction was completed. The resulting polymer was cut to obtain chemically recycled polyester pellets (recycled pellets B). The recycled material rate of recycled pellets B was 99.4%.

(Recycled pellet C)
The flakes obtained by crushing PET bottles were melt-extruded by an extruder and cut to obtain mechanically recycled polyester pellets (recycled pellets C). The recycled material rate of the recycled pellets C was 100%.

(Recycled pellet D)
In a rotary dryer, the recycled pellets C obtained above were exposed to a nitrogen stream containing ethylene glycol vapor at 0.086 g/(hr·pellet kg) (=86 ppm) per unit time per 1 kg of pellets, and the recovered pellets and ethylene glycol were contacted for 6 hours. The treatment temperature was 220°C. Furthermore, 0.04 parts by mass of ethyl acid phosphate was added to this reaction mixture, and then 0.5 parts by mass of spherical organic crosslinked particles with an average particle size of 1.1 μm and 0.03 parts by mass of antimony trioxide were added, and a polycondensation reaction was carried out for 4 hours, followed by solid-phase polymerization for 20 hours at 0.5 mmHg and 230°C, and the resulting polymer was cut to obtain chemically recycled polyester pellets (recycled pellets D). The recycled raw material rate of the recycled pellets D was 99.4%.

(Virgin pellet E)
100 parts by mass of dimethyl terephthalate and 60 parts by mass of ethylene glycol were used as starting materials, and 0.09 parts by mass of magnesium acetate tetrahydrate was taken into a reactor as a catalyst. The reaction was started at 150°C, and the reaction temperature was gradually increased with the distillation of methanol, and reached 230°C after 3 hours. After 4 hours, the transesterification reaction was essentially completed. After adding 0.04 parts by mass of ethyl acid phosphate to this reaction mixture, 0.5 parts by mass of spherical organic crosslinked particles having an average particle size of 1.1 μm and 0.03 parts by mass of antimony trioxide were added, and a polycondensation reaction was carried out for 4 hours. Meanwhile, the pressure was gradually reduced from normal pressure, and finally reached 0.3 mmHg. After the start of the reaction, the reaction was stopped at a point corresponding to an intrinsic viscosity of 0.65 due to a change in the stirring power of the reaction vessel, and the polymer was discharged under nitrogen pressure to obtain virgin polyester pellets (virgin pellets E). The recycled raw material rate of virgin pellets E was 0%.

2. Production of polyester film <Polyester film 1>
50 parts by mass of recycled pellets A and 50 parts by mass of virgin pellets E were uniformly mixed, melt-extruded at 295° C. using a vented twin-screw extruder, and cooled and solidified on a cooling roll with a surface temperature set at 38° C. using an electrostatic adhesion method to obtain an unstretched sheet. The sheet was then stretched 4 times in the longitudinal direction at 82° C., introduced into a tenter, stretched 4 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a single-layer polyester film 1 having a thickness of 2.0 μm (recycled material ratio 50.0%).

<Polyester film 2>
70 parts by mass of recycled pellets A and 30 parts by mass of virgin pellets E were uniformly mixed, melt-extruded at 295°C using a vented twin-screw extruder, and cooled and solidified on a cooling roll with a surface temperature set at 38°C using an electrostatic adhesion method to obtain an unstretched sheet. Next, the sheet was stretched 4 times in the longitudinal direction at 82°C, introduced into a tenter, stretched 4 times in the transverse direction at 110°C, and further heat-treated at 225°C to obtain a single-layer polyester film 2 (recycled material ratio 70.0%) having a thickness of 2.0 μm.

<Polyester film 3>
90 parts by mass of recycled pellets A and 10 parts by mass of virgin pellets E were uniformly mixed, melt-extruded at 295° C. using a vented twin-screw extruder, and cooled and solidified on a cooling roll with a surface temperature set at 38° C. using an electrostatic adhesion method to obtain an unstretched sheet. The sheet was then stretched 4 times in the longitudinal direction at 82° C., introduced into a tenter, stretched 4 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a single-layer polyester film 3 having a thickness of 2.0 μm (recycled material ratio 90.0%).

<Polyester film 4>
100 parts by mass of the recycled pellets B were melt-extruded at 295° C. using a vented twin-screw extruder, and cooled and solidified on a cooling roll with a surface temperature set at 38° C. using an electrostatic adhesion method to obtain an unstretched sheet. The sheet was then stretched 4 times in the longitudinal direction at 82° C., introduced into a tenter, stretched 4 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a single-layer polyester film 4 having a thickness of 2.0 μm (recycled material ratio 99.4%).

<Polyester film 5>
50 parts by mass of recycled pellets B and 50 parts by mass of virgin pellets E were uniformly mixed, melt-extruded at 295° C. using a vented twin-screw extruder, and cooled and solidified on a cooling roll with a surface temperature set at 38° C. using an electrostatic adhesion method to obtain an unstretched sheet. The sheet was then stretched 4 times in the longitudinal direction at 82° C., introduced into a tenter, stretched 4 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a single-layer polyester film 5 having a thickness of 2.0 μm (recycled material ratio 49.7%).

<Polyester film 6>
50 parts by mass of recycled pellets A and 50 parts by mass of recycled pellets B were uniformly mixed, melt-extruded at 295° C. using a vented twin-screw extruder, and cooled and solidified on a cooling roll with a surface temperature set at 38° C. using an electrostatic adhesion method to obtain an unstretched sheet. The sheet was then stretched 4 times in the longitudinal direction at 82° C., introduced into a tenter, stretched 4 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a single-layer polyester film 6 having a thickness of 2.0 μm (recycled material ratio 99.7%).

<Polyester film 7>
95 parts by mass of recycled pellets A and 5 parts by mass of virgin pellets E were mixed, melt-extruded at 295° C. using a vented twin-screw extruder, and cooled and solidified on a cooling roll with a surface temperature set at 38° C. using an electrostatic adhesion method to obtain an unstretched sheet. The sheet was then stretched 2.5 times in the longitudinal direction at 82° C., introduced into a tenter, stretched 2.4 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a single-layer polyester film 7 (recycled material ratio 95.0%) having a thickness of 6.0 μm.

<Polyester film 8>
50 parts by mass of recycled pellets C and 50 parts by mass of virgin pellets E were mixed, melt-extruded at 295° C., and cooled and solidified on a cooling roll with a surface temperature set to 38° C. using an electrostatic adhesion method to obtain an unstretched sheet. The sheet was then stretched 4 times in the longitudinal direction at 82° C., introduced into a tenter, stretched 4 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a single-layer polyester film 8 (recycled material ratio 50.0%) having a thickness of 2.0 μm.

<Polyester film 9>
Virgin pellets E were melt extruded at 295° C. and cooled and solidified on a cooling roll with a surface temperature set at 38° C. using an electrostatic adhesion method to obtain an unstretched sheet. Then, the sheet was stretched 4 times in the longitudinal direction at 82° C., introduced into a tenter and stretched 4 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a single-layer polyester film 9 (recycled material rate 0.0%) having a thickness of 2.0 μm.

<Polyester film 10>
The recycled pellets C were melt extruded at 295° C. and cooled and solidified on a cooling roll with a surface temperature set at 38° C. using an electrostatic adhesion method to obtain an unstretched sheet. The sheet was then stretched 4 times in the longitudinal direction at 82° C., introduced into a tenter and stretched 4 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a single-layer polyester film 10 (recycled material ratio 100%) having a thickness of 2.0 μm.

<Polyester film 11>
Using a vented twin-screw extruder capable of three-layer extrusion of layer 1/layer 2/layer 3 (cooling roll layer side), virgin pellets E were used as the material for layer 1, recycled pellets C as the material for layer 2, and virgin pellets E as the material for layer 3, and melt extruded at 295°C, and cooled and solidified on a cooling roll with a surface temperature set to 38°C using an electrostatic application adhesion method to obtain an unstretched sheet. Next, the polyester film was stretched 1.8 times in the longitudinal direction at 82°C, introduced into a tenter, stretched 2.0 times in the transverse direction at 110°C, and further heat-treated at 225°C to produce a polyester film 11 having a three-layer structure of layer 1/layer 2/layer 3 and a thickness of 2 μm, but the film was broken during the production process and could not be produced. The minimum thickness of a polyester film having a three-layer structure that can be produced by the above method was 12 μm.

<Polyester film 12>
Using a vented twin screw extruder capable of three-layer extrusion of layer 1/layer 2/layer 3 (cooling roll layer side), recycled pellets D were used as the material for layer 1, recycled pellets C as the material for layer 2, and recycled pellets D as the material for layer 3, and melt extruded at 295° C., and cooled and solidified on a cooling roll with a surface temperature set to 38° C. using an electrostatic application adhesion method to obtain an unstretched sheet. Next, the film was stretched 1.8 times in the longitudinal direction at 82° C., introduced into a tenter, stretched 2.0 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a polyester film 12 (recycled material rate 99.8%) having a three-layer structure of layer 1 (thickness 5 μm)/layer 2 (thickness 15 μm)/layer 3 (thickness 5 μm).

<Polyester film 13>
Using a vented twin screw extruder capable of three-layer extrusion of layer 1/layer 2/layer 3 (cooling roll layer side), virgin pellets E were used as the material for layer 1, recycled pellets C as the material for layer 2, and virgin pellets E as the material for layer 3, and melt extruded at 295°C, and cooled and solidified on a cooling roll with a surface temperature set to 38°C using an electrostatic application adhesion method to obtain an unstretched sheet. Next, the film was stretched 1.8 times in the longitudinal direction at 82°C, introduced into a tenter, stretched 2.0 times in the transverse direction at 110°C, and further heat-treated at 225°C to obtain a polyester film 13 (recycled material rate 84.0%) having a three-layer structure of layer 1 (thickness 2 μm)/layer 2 (thickness 21 μm)/layer 3 (thickness 2 μm).

<Polyester film 14>
The virgin pellets E were melt-extruded at 295° C. using a vented twin-screw extruder, and cooled and solidified on a cooling roll with a surface temperature set at 38° C. using an electrostatic adhesion method to obtain an unstretched sheet. The sheet was then stretched 1.8 times in the machine direction at 82° C., introduced into a tenter, and stretched 2.0 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a single-layer polyester film 14 having a thickness of 25 μm (recycled material rate 0%).

<Polyester film 15>
The recycled pellets C were melt-extruded at 295° C. using a vented twin-screw extruder, and cooled and solidified on a cooling roll with a surface temperature set at 38° C. using an electrostatic adhesion method to obtain an unstretched sheet. The sheet was then stretched 1.8 times in the longitudinal direction at 82° C., introduced into a tenter, and stretched 2.0 times in the transverse direction at 110° C., and further heat-treated at 225° C. to obtain a single-layer polyester film 15 (recycled material ratio 100%) having a thickness of 25 μm.

The outline of polyester films 1 to 15 is shown in the table below.

3. Preparation of Black Ink A 50 parts by mass of isophthalic acid, 50 parts by mass of neopentyl glycol, 60 parts by mass of toluene, and 40 parts by mass of methyl ethyl ketone were added to a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, and reacted at 80° C. for 10 hours with stirring to obtain a polyester polyol resin A having a resin solids content of 50% and a weight average molecular weight of 40,000.

100 parts by weight of the polyester polyol resin A (resin solid content 50% by weight), 40 parts by weight of carbon black "Carbon Special 250P" manufactured by Degussa, 23 parts by weight of methyl ethyl ketone, 13 parts by weight of toluene, 6 parts by weight of ethyl acetate, 3 parts by weight of N-propyl acetate, and 3 parts by weight of isopropyl alcohol were added and wet dispersed in a sand mill for about 1 hour. To the mixture, 2 parts by weight of hardener "KR90" manufactured by DIC (biuret form of hexamethylene diisocyanate, solid content 40% by weight) and 300 parts by weight of ethyl acetate were added to prepare black ink A. The carbon black content in the black ink solid content was 44% by weight.

4. Production of colored film <Colored film 1>
In a clean room, one side of polyester film 1 was directly gravure coated three times with black ink A to a dry thickness of 2.0 μm, and aged at 40° C. for one day to obtain black ink coated film 1 (colored film 1 in which a black colored layer was formed on one side of polyester film 1). The recycled material rate and biomass degree of colored film 1 are as shown in Table 2 below. The colored layer was a reaction cured product of polyester polyol resin A of black ink A and a curing agent, and the glass transition temperature in the colored layer was 51.0° C. The glass transition temperature of the colored layer was a value measured using DSC in accordance with ISO 3146.

<Colored films 2 to 10>
Colored films 2 to 10 were obtained in the same manner as for colored film 1, except that polyester films 2 to 10 were used instead of polyester film 1. The recycled material ratio and biomass degree of each of colored films 2 to 10 are as shown in Table 2 below.

5. Production of release liner <Release liner 1>
One side of the polyester film 12 was subjected to a corona treatment, and an addition reaction type silicone-based release agent A was applied to the corona treated surface using a microgravure coater so that the thickness after drying would be 0.1 μm, and the coating was heated in a hot air circulation type dryer at 110° C. for 1 minute and aged at 40° C. for 2 days to obtain a release liner 1 (recycled material rate 99.4%, biomass rate 0.0%). The addition reaction type silicone-based release agent A was a mixture of 10 parts by mass of SRX-211 manufactured by Dow Corning Toray Co., Ltd., 0.1 parts by mass of SRX212, a platinum catalyst, and 90 parts by mass of a 50/50 mixed solvent of toluene/ethyl acetate.

<Release Liners 2 to 4>
Release Liners 2 to 4 were obtained in the same manner as Release Liner 1, except that Polyester Film 12 was replaced with Polyester Films 13 to 15. The recycled material ratio and biomass degree of Release Liners 2 to 4 are shown in Tables 2 and 3 below.

6. Preparation of adhesive <Polyester adhesive α>
In a reaction vessel equipped with a thermometer, a stirrer, a distillation column, a nitrogen inlet tube and a vacuum device, 520 parts by mass of hydrodistilled dimer acid, 59 parts by mass of polyethylene terephthalate (PET), 108 parts by mass of ethylene glycol, and 1 part by mass of trimethylolpropane were blended as polycarboxylic acids and polyols, and 0.2 mmol/mol of tetrabutyl titanate was charged as a catalyst relative to the polycarboxylic acids, and the internal temperature was gradually increased to 240 to 250 ° C., and an esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was increased to 260 ° C., and 0.2 mmol/mol of tetrabutyl titanate was charged as a catalyst relative to the polycarboxylic acids, the pressure was reduced to 1.33 to 2.66 hPa, and a polymerization reaction was carried out over 2 to 3 hours to produce a polyester resin. In the above production, the hydrodistilled dimer acid and ethylene glycol were raw materials derived from biomass, and the polyethylene terephthalate (PET) was a recycled raw material (recycled raw material rate 100%).

The composition of the obtained polyester resin was 75.4 parts by mass of dimer acid, 25 parts by mass of terephthalic acid, 99 parts by mass of ethylene glycol, and 0.6 parts by mass of trimethylolpropane, where the dimer acid and ethylene glycol were biomass raw materials (biomass raw material ratio 100%), and the terephthalic acid was a recycled raw material derived from polyethylene terephthalate (PET). The polyester resin had a number average molecular weight of 10,000, a weight average molecular weight of 75,000, and a glass transition temperature of -41°C. The biomass degree of the polyester resin was 87.2%, the recycled raw material ratio was 12.5%, and the recycled and biomass raw material ratio was 99.7%.

100 parts by solids of the polyester resin obtained above and 15 parts by solids of polymerized rosin ester (product name "D-135" manufactured by Arakawa Chemical Industries Co., Ltd.) were diluted with ethyl acetate to a solid concentration of 50%, and 1.2 parts by solids of an isocyanate crosslinking agent "Coronate L55E, solid concentration 55%" and 1 part by solids of a hydrolysis inhibitor "Carbodilite V-09GB, solid concentration 70%" (manufactured by Nisshinbo Chemical Co., Ltd.) were blended. 0.02 parts by solids of a zirconium compound ("Orgatics ZC-150" manufactured by Matsumoto Fine Chemical Co., Ltd.) diluted with acetylacetone to a solid concentration of 1% as a urethane catalyst were added, stirred and mixed to obtain polyester adhesive α. The biomass degree of the polyester adhesive α was 87.0%, the recycled raw material rate was 10.6%, and the recycled and biomass raw material rate was 97.6%.

<Acrylic adhesive β>
97.98 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid, 0.02 parts by mass of 4-hydroxybutyl acrylate, and 0.2 parts by mass of azobisisobutyronitrile as a polymerization initiator were solution-polymerized in an ethyl acetate solution at 80° C. for 8 hours to obtain an acrylic polymer having a weight-average molecular weight of 900,000. 50 parts by mass of polymerized rosin ester (trade name "D-135" manufactured by Arakawa Chemical Industries Co., Ltd.) was added to 100 parts by mass of the acrylic polymer in terms of solid content, and ethyl acetate was added to prepare an adhesive solution having a solid content of 40% by mass. 1 part by mass of an isocyanate-based crosslinking agent (trade name "NC40" manufactured by DIC Corporation) was further added in terms of solid content to the above adhesive solution, and the mixture was stirred and mixed to be uniform, thereby preparing an acrylic adhesive β. The polymerized rosin ester was a biomass raw material. The acrylic adhesive β had a biomass degree of 32.8%, a recycled raw material rate of 0.0%, and a recycled and biomass raw material rate of 32.8%.

7. Creating colored adhesive tape (Example 1)
A polyester-based adhesive α was applied to the release agent-coated surface of the release liner 1 using a microgravure coater so that the thickness after drying would be 2 μm, and an adhesive layer was formed by drying for 2 minutes at 100° C. The polyester film side surface of the colored film 1 was attached to the above-mentioned adhesive layer, and aged at 40° C. for 1 week, to prepare a colored adhesive tape of Example 1 having a laminated structure of colored film (colored layer/polyester film)/adhesive layer/release liner.

(Examples 2 to 7)
Colored adhesive tapes of Examples 2 to 7 were prepared in the same manner as in Example 1, except that Colored Film 1 was replaced by Colored Films 2 to 7.

(Example 8)
A colored adhesive tape of Example 8 was prepared in the same manner as in Example 1, except that Release Liner 2 was used in place of Release Liner 1 and Colored Film 8 was used in place of Colored Film 1.

(Example 9)
A colored adhesive tape of Example 9 was prepared in the same manner as in Example 1, except that the polyester adhesive α was replaced with the acrylic adhesive β.

(Example 10)
The colored adhesive tape of Example 10 was prepared in the same manner as in Example 1, except that release liner 3 was used instead of release liner 1, colored film 9 was used instead of colored film 1, and acrylic adhesive β was used instead of polyester adhesive α.

(Example 11)
A colored adhesive tape of Example 11 was prepared in the same manner as in Example 1, except that the colored film 10 was used instead of the colored film 1 and the acrylic adhesive β was used instead of the polyester adhesive α.

(Example 12)
The colored adhesive tape of Example 12 was prepared in the same manner as in Example 1, except that release liner 4 was used instead of release liner 1, colored film 9 was used instead of colored film 1, and acrylic adhesive β was used instead of polyester adhesive α.

The compositions of the colored adhesive tapes obtained in Examples 1 to 12 are shown in Tables 2 to 3 below.

8. Evaluation The colored adhesive tapes obtained in Examples 1 to 12 were evaluated by the following evaluation methods.

<Recycled material rate>
Using the formula described above, the recycled material rate of each layer constituting the colored adhesive tape was calculated. In addition, the recycled material rate of the entire colored adhesive tape was calculated and evaluated according to the following criteria. The results are shown in Tables 1 to 4.
(Evaluation criteria)
◎: The recycled material rate of the colored adhesive tape is 85% or more (has excellent environmental protection performance)
Good: The recycled material rate of the colored adhesive tape is 70% or more and less than 85% (has sufficient environmental protection performance for practical use).
×: The recycled material rate of the colored adhesive tape is less than 70% (does not have sufficient environmental protection performance)

<Biomass ratio>
The biomass degree of each layer constituting the colored adhesive tape and the biomass degree of the entire colored adhesive tape were calculated using the calculation formula described above. The results are shown in Tables 1 to 4.

<Recycled and biomass raw material ratio>
Using the formula described above, the ratio of recycled materials and biomass materials (recycled and biomass raw material ratio) of the entire colored adhesive tape was calculated and evaluated according to the following criteria. The results are shown in Table 4.
(Evaluation criteria)
◎: Colored adhesive tape is recycled and contains 90% or more biomass raw materials (has excellent environmental protection properties)
Good: The recycled and biomass raw material rate of the colored adhesive tape is 70% or more and less than 90% (has sufficient environmental protection performance for practical use).
×: The recycled and biomass raw material rate of the colored adhesive tape is less than 70% (does not have sufficient environmental protection performance)

<Ease of recycling colored adhesive tape>
The recyclability (ease of recycling) of the colored adhesive tapes was evaluated according to the following criteria. The results are shown in Table 4.
(standard)
◎: The percentage of polyester-based material in the colored adhesive tape is 90% or more (has excellent recyclability)
Good: The percentage of polyester-based material in the colored adhesive tape is 70% or more and less than 90% (sufficient recyclability for practical use)
×: The proportion of polyester-based material in the colored adhesive tape is less than 70% (not sufficiently suitable for recycling)

<Printability>
When viewed from the colored layer side of the colored adhesive tape, the number of ink spots of 0.25 mm2 or ^more present in ¹⁰⁰⁰ m2 of the colored layer (1 m x 1000 m square) was visually confirmed and evaluated according to the following criteria. The results are shown in Table 4.
(Evaluation criteria)
◎: No ink loss (excellent printability)
Good: 1 to 10 ink spots (sufficient for practical printing)
×: More than 10 ink spots (not sufficiently suitable for printing)

<Adhesive coating suitability (appearance)>
The release liner of the colored adhesive tape was peeled off, and the number of bubbles (air bubbles) of ¹ mm2 or more present in 1000 ^m2 (1 m x 1000 m square) of the adhesive layer was visually confirmed from the adhesive layer side and evaluated according to the following criteria. The results are shown in Table 4.
(Evaluation criteria)
◎: 0 bubbles (excellent coating suitability)
Good: 1 to 10 bubbles (sufficient for practical application)
×: 11 or more bubbles (not sufficiently suitable for coating)

<Thinness of colored adhesive tape>
The thickness of the colored adhesive tape was measured to the nearest 0.1 μm using Nikon's Digimicro MF-501, MCF-101, and MS-31G, and evaluated according to the following criteria. The results are shown in Table 4.
(Evaluation criteria)
◎: The thickness of the colored adhesive tape is 9 μm or less (has excellent thinness performance)
◯: The thickness of the colored adhesive tape is more than 9 μm and 20 μm or less (has a thin performance sufficient for practical use)
×: The thickness of the colored adhesive tape is more than 20 μm (not having sufficient thinness performance)

<Adhesiveness>
The colored adhesive tape was cut to a width of 25 mm, and the peel adhesion was measured using a Tensilon tensile tester in accordance with JIS Z0237 (peel angle: 180°, tensile speed: 300 mm/min, 23°C x 50% RH, adherend: stainless steel plate, application time: 1 hour). The results are shown in Table 4.

<Holding power>
The colored adhesive tape was cut to a width of 25 mm, and a load of 100 g (25 mm x 25 mm) was applied vertically in accordance with JIS Z0237, and the fall time (unit: hour) was measured in an atmosphere at 100° C. The results are shown in Table 4.

<Alcohol resistance of the colored layer surface>
The same spot on the surface of the colored layer side of the colored adhesive tape was rubbed 50 times with a cotton swab soaked in ethanol, and the number of rubs at which the colored layer faded and the cotton swab became stained was measured and evaluated according to the following criteria. A higher number of rubs indicates better alcohol resistance. The results are shown in Table 4.
(Evaluation criteria)
◎: 50 times or more 〇: 25 times or more and 49 times or less ×: 24 times or less

<Ink adhesion>
A cellophane tape manufactured by Nichiban Co., Ltd. was applied to the surface of the colored layer, and the tape was rubbed with the pad of a thumb 5 or 6 times to adhere to the surface. After leaving the tape for about 1 minute, one end of the cellophane tape on both sides was held and forcefully peeled off in a 180° direction (peeling speed: about 50 m/min). The state of the colored adhesive tape after peeling was evaluated according to the following criteria. The results are shown in Table 4.
(Evaluation criteria)
⊚: No ink loss at all, or the colored film is torn off. ◯: Ink loss occurs in less than 5% of the area where the cellophane tape is applied (ink transfer can be confirmed with the naked eye to the cellophane tape side, but cannot be determined with the naked eye on the colored film).
Δ: Ink loss occurs in an area of 5% to 30% of the area where the cellophane tape is applied.
x: Ink loss occurs over more than 30% of the area where the cellophane tape is applied.

In Table 4, "colored adhesive tape" is simply referred to as "tape."

(Discussion)
The colored adhesive tapes of Examples 1 to 9 and Examples 11 to 12 (Examples) had a total thickness of 20 μm or less excluding the release liner and a recycled material rate of 70% or more, and were therefore thin colored adhesive tapes with a high recycled material rate. On the other hand, the colored adhesive tape of Example 10 (Comparative Example) had a recycled material rate of 0%, and was therefore poor in environmental friendliness.

In addition, among Examples 1 to 9 and Examples 11 to 12, the colored adhesive tapes of Examples 1 to 9 were evaluated as being good in terms of printability and adhesive coating suitability, with a rating of "◎" or "◯", and their adhesive strength was equivalent to that of Example 10, in which neither the substrate nor the release liner contained recycled resin. On the other hand, the colored adhesive tape of Example 11, which used polyester film 10 as the substrate, was evaluated as being inferior to Examples 1 to 9 in terms of printability, and many ink bleeds (print bleeds) occurred during the formation of the colored layer. The colored adhesive tape of Example 12, which used polyester film 15 as the release liner, was evaluated as being inferior to Examples 1 to 9 in terms of adhesive coating suitability, and the occurrence of air bubbles in the adhesive layer increased. The colored adhesive tape of Example 12 used the same acrylic adhesive β as Example 9, and the thickness of the adhesive layer was also the same, but its adhesive strength was inferior to that of Example 9. These differences are due to the fact that the substrate and release liner in contact with the adhesive layer and colored layer in the colored adhesive tapes of Examples 1 to 9 were specified, thereby suppressing the occurrence of defects in the adhesive layer and colored layer.

In the production of polyester film 11, the minimum total thickness that can be produced for a three-layer polyester film is 12 μm, and it was not possible to produce a polyester film with a total thickness of 9 μm or less. It was suggested that a single-layer or two-layer substrate be used to obtain a colored adhesive tape that can achieve the desired recycled material rate and has a total thickness excluding the release liner of 12 μm or less, particularly 10 μm or less.

1...Substrate, 2...Colored layer, 3...Adhesive layer, 4...Release liner, 10...Colored adhesive tape

Claims (12)

A substrate; a colored layer provided on one surface of the substrate;
A pressure-sensitive adhesive layer provided on the other surface of the substrate;
a release liner provided on the surface of the pressure-sensitive adhesive layer;
having
At least the substrate and the release liner each contain recycled resin;
the total thickness of the colored adhesive tape excluding the release liner is 20 μm or less;
The colored adhesive tape comprises 70% by mass or more of recycled raw materials. The thickness of the substrate is 9 μm or less,
The substrate is
A single-layer structure having one layer in which the recycled resin content is 50% by mass or more and 100% by mass or less and the mechanical recycled resin content is 95% by mass or less, or a two-layer structure having two of the above layers,
The release liner is
A single-layer structure having a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanically recycled resin content of 95% by mass or less, or
2. The colored adhesive tape according to claim 1, wherein the outermost layer on the adhesive layer side has a multilayer structure in which the outermost layer is a layer having a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanically recycled resin content of 95% by mass or less, or a layer having a virgin resin content of 50% by mass or more. The colored adhesive tape according to claim 1 or 2, wherein the content of recycled resin in the release liner is 90% by mass or more. The colored adhesive tape according to claim 1 or 2, wherein the thickness of the adhesive layer is 9 μm or less. the release liner has a three-layer structure having a Layer B1, a Layer B2, and a Layer B3 in this order from the PSA layer side,
The layer B1 and the layer B3 each have a recycled resin content of 50% by mass or more and 100% by mass or less and a mechanically recycled resin content of 95% by mass or less, or a virgin resin content of 50% by mass or more,
The colored pressure-sensitive adhesive tape according to claim 1 or 2, wherein the layer B2 is a layer having a mechanically recycled resin content of 50% by mass or more and 100% by mass or less. The colored adhesive tape according to claim 1 or 2, wherein the recycled resin contained in the release liner is a recycled polyester resin. The colored adhesive tape according to claim 1 or 2, wherein the recycled resin contained in the substrate is a recycled polyester resin. the colored adhesive tape comprises a biomass material;
3. The colored adhesive tape according to claim 1, wherein the content of recycled raw materials and biomass raw materials in the colored adhesive tape is 75% by mass or more. A method for producing the colored adhesive tape according to claim 1 or 2, comprising the steps of:
A colored layer forming step of forming a colored layer on one surface of a substrate containing recycled resin;
a pressure-sensitive adhesive layer forming step of applying a pressure-sensitive adhesive to the other surface of the base material to form a pressure-sensitive adhesive layer;
a lamination step of laminating a release liner containing a recycled resin on the surface of the pressure-sensitive adhesive layer;
The method for producing a colored adhesive tape comprising the steps of: A method for producing the colored adhesive tape according to claim 1 or 2, comprising the steps of:
an adhesive layer forming step of applying an adhesive to a release liner containing a recycled resin to form an adhesive layer, thereby obtaining a release liner with an adhesive layer;
A colored layer forming step of forming a colored layer on one surface of a substrate containing recycled resin;
a bonding step of bonding the surface of the release liner with the pressure-sensitive adhesive layer on the pressure-sensitive adhesive layer side to the other surface of the base material;
The method for producing a colored adhesive tape comprising the steps of: A method for producing the colored adhesive tape according to claim 1 or 2, comprising the steps of:
a pressure-sensitive adhesive layer forming step of applying a pressure-sensitive adhesive to one surface of a substrate containing a recycled resin to form a pressure-sensitive adhesive layer;
a lamination step of laminating a release liner containing a recycled resin on a surface of the pressure-sensitive adhesive layer;
a colored layer forming step of forming a colored layer on the other surface of the base material;
The method for producing a colored adhesive tape comprising the steps of: A method for producing the colored adhesive tape according to claim 1 or 2, comprising the steps of:
an adhesive layer forming step of applying an adhesive to a release liner containing a recycled resin to form an adhesive layer, thereby obtaining a release liner with an adhesive layer;
a lamination step of laminating a substrate containing a recycled resin onto a surface of the pressure-sensitive adhesive layer of the release liner with the pressure-sensitive adhesive layer;
a colored layer forming step of forming a colored layer on the surface of the base material;
The method for producing a colored adhesive tape comprising the steps of:

Images