CN118165662A

CN118165662A - Adhesive tape and method for producing same

Info

Publication number: CN118165662A
Application number: CN202211577615.1A
Authority: CN
Inventors: 山上晃; 沈骏文; 今井克明; 高桥佑辅
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 2022-12-09
Filing date: 2022-12-09
Publication date: 2024-06-11
Also published as: JP2024083274A

Abstract

The invention provides an adhesive tape and a method for manufacturing the same. The adhesive tape comprises a base material, an adhesive layer provided on one or both sides of the base material, and a release liner provided on the surface of the adhesive layer on at least one side of the base material, wherein at least the base material and the release liner each contain a recycled resin, the total thickness of the adhesive tape excluding the release liner is greater than 20 [ mu ] m, and the proportion of recycled material in the adhesive tape is 30 mass% or more. The adhesive tape is thick and has a high regeneration raw material rate.

Description

Adhesive tape and method for producing same

Technical Field

The present invention relates to a thick adhesive tape having a high regeneration raw material rate.

Background

In recent years, resin products having a high ratio of a regenerated raw material (hereinafter, sometimes referred to as a regenerated raw material ratio) have been demanded for the purpose of reducing environmental load such as reduction of carbon dioxide emissions. As such a resin product, for example, there is a regenerated resin film formed using a regenerated resin obtained by recovering and regenerating a used resin.

For example, patent document 1 discloses a laminate having a polyester film base material containing a chemically recycled polyester resin.

Patent document 2 discloses a biaxially oriented polyester film containing a recycled polyester resin recycled from a plastic bottle in a predetermined ratio.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2022-7900

Patent document 2: international publication No. 2022/071440 booklet

Disclosure of Invention

Problems to be solved by the invention

The single-sided or double-sided pressure-sensitive adhesive tape includes at least a pressure-sensitive adhesive layer, a base material, and a release liner in the constituent members, but most of the constituent members are made of petroleum resin. In particular, the greater the thickness of the adhesive tape, the greater the proportion of petroleum resin used tends to be. Therefore, from the viewpoint of environmental friendliness, it is demanded to increase the regeneration raw material rate in the whole adhesive tape.

The present invention has been made in view of the above problems, and provides a thick pressure-sensitive adhesive tape having a high recycling rate.

Means for solving the problems

The present invention includes the following embodiments.

[1] An adhesive tape comprising a substrate, an adhesive layer provided on one or both sides of the substrate, and a release liner provided on the surface of the adhesive layer on at least one side of the substrate, wherein at least the substrate and the release liner each contain a recycled resin, the total thickness of the adhesive tape excluding the release liner is greater than 20 [ mu ] m, and the proportion of recycled material in the adhesive tape is 30% by mass or more.

[2] The adhesive tape according to the above [1], wherein the base material has:

A single-layer structure in which the content of the regenerated resin is 50 mass% or more and 100 mass% or less and the content of the mechanically regenerated resin is 95 mass% or less; or alternatively

The following multilayer structure: the outermost layer on the pressure-sensitive adhesive layer side is a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less, or a layer having a content of a virgin resin of 50 mass% or more.

[3] The adhesive tape according to the above [1] or [2], wherein the base material has a three-layer structure having a layer A1, a layer A2 and a layer A3 in this order from the adhesive layer side, and the layer A1 and the layer A3 are each a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less; or a layer having a virgin resin content of 50 mass% or more, wherein the layer A2 is a layer having a mechanically regenerated resin content of 50 mass% or more and 100 mass% or less.

[4] The adhesive tape according to any one of the above [1] to [4], wherein the content of the regenerated resin of the base material is 90% by mass or more.

[5] The adhesive tape according to any one of the above [1] to [4], wherein the recycled resin contained in the base material is a recycled polyester resin.

[6] The adhesive tape according to any one of the above [1] to [5], wherein the release liner comprises:

[7] The adhesive tape according to any one of the above [1] to [6], wherein the release liner has a three-layer structure including, in order from the adhesive layer side, a layer B1, a layer B2, and a layer B3, and the layer B1 and the layer B3 are each a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less; or a layer having a virgin resin content of 50 mass% or more, and the layer B2 is a layer having a mechanically regenerated resin content of 50 mass% or more and 100 mass% or less.

[8] The adhesive tape according to any one of the above [1] to [7], wherein the content of the regenerated resin of the release liner is 90 mass% or more.

[9] The adhesive tape according to any one of the above [1] to [8], wherein the recycled resin contained in the release liner is a recycled polyester resin.

[10] The adhesive tape according to any one of the above [1] to [9], wherein the thickness of the adhesive layer is 9 μm or more and 100 μm or less.

[11] The pressure-sensitive adhesive tape according to any one of the above [1] to [10], wherein the pressure-sensitive adhesive tape further comprises a biomass material, and the ratio of the regenerated raw material to the biomass raw material in the pressure-sensitive adhesive tape is 60% by mass or more.

[12] The method for producing an adhesive tape according to any one of the above [1] to [11], comprising at least the steps of: an adhesive layer forming step of forming an adhesive layer by applying an adhesive to at least one surface of a base material containing a recycled resin; and a bonding step of bonding a release liner containing a recycled resin to the surface of the adhesive layer on at least one surface side of the base material.

[13] The method for producing an adhesive tape according to the above [12], wherein,

The base material and the release liner each independently have:

A single-layer structure in which the content of the regenerated resin is 50 mass% or more and 100 mass% or less and the content of the mechanically regenerated resin is 95 mass% or less;

The following multilayer structure: at least one outermost layer is a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less, or a layer having a content of a virgin resin of 50 mass% or more;

In the adhesive layer forming step, an adhesive is applied to at least one surface of the single-layer substrate or at least one surface of the outermost layer of the multi-layer substrate to form an adhesive layer,

In the bonding step, a surface of the adhesive layer on at least one surface side of the base material is bonded to one surface of the release liner having a single layer structure or to a surface of the outermost layer of the release liner having a multilayer structure.

[14] The method for producing an adhesive tape according to any one of the above [1] to [11], comprising at least the steps of: an adhesive layer forming step of forming an adhesive layer by applying an adhesive to a release liner containing a recycled resin, thereby obtaining a release liner with an adhesive layer; and a bonding step of bonding the surface of the pressure-sensitive adhesive layer-attached release liner to at least one surface of a base material containing a recycled resin.

[15] The method for producing an adhesive tape according to the above [14], wherein the base material and the release liner each independently have:

in the adhesive layer forming step, an adhesive is applied to one surface of the release liner having a single layer structure or to the surface of the outermost layer of the release liner having a multilayer structure to form an adhesive layer,

In the bonding step, the adhesive layer of the release liner with an adhesive layer is bonded to at least one surface of the single-layer substrate or the one outermost layer of the multi-layer substrate.

Effects of the invention

According to the present invention, a thick adhesive tape having a high recycling rate can be provided.

Drawings

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

Fig. 2 is a schematic cross-sectional view showing an example of the pressure-sensitive adhesive tape of the present invention.

Fig. 3 is a schematic cross-sectional view showing an example of the pressure-sensitive adhesive tape of the present invention.

Fig. 4 is a schematic cross-sectional view showing an example of the pressure-sensitive adhesive tape of the present invention.

Detailed Description

In the present specification, the regenerated resin is a resin obtained by regenerating a recovered used resin, and includes a chemically regenerated resin, a mechanically regenerated resin, and the like. The regenerated resin may be a petroleum resin obtained from petroleum resources, a biomass resin obtained from non-petroleum resources (biomass resources) such as plants, or a mixture thereof. The resin used as the raw material of the regenerated resin may be a petroleum resin, a biomass resin, a chemically regenerated resin, a mechanically regenerated resin, or a mixture thereof.

In the present specification, the mechanically regenerated resin means: the resin is obtained by washing and pulverizing the recovered used resin, melting the resin at a high temperature, and extruding the resin (mechanical regeneration method).

In the present specification, the chemically regenerated resin means: the resin is obtained by removing impurities by screening, pulverizing and washing the recovered used resin, depolymerizing the resin to decompose the resin material or intermediate material, purifying the resin material, and polymerizing the obtained material again (chemical regeneration method). The chemically regenerated resin may be obtained by directly repolymerizing the oligomer mixture without adding other functional additives thereto during the regeneration process, or may be an electrostatic adhesion chemically regenerated resin obtained by adding an electrostatic adhesion agent to the oligomer mixture and then repolymerizing the oligomer mixture. The electrostatic adhesion chemically regenerated resin includes a chemically regenerated resin and an electrostatic adhesion agent.

In the present specification, the virgin resin means: the unused resin, i.e., the non-regenerated resin, is a resin that does not use the used raw materials. The virgin resin may be petroleum resin, biomass resin, or a mixture thereof.

In the present specification, the ratio of the regeneration raw material in the pressure-sensitive adhesive tape (regeneration raw material ratio of the pressure-sensitive adhesive tape) means: the regeneration raw material used in manufacturing the adhesive tape accounts for a mass ratio of the total mass of the adhesive tape including the release liner. The ratio of the regeneration raw material in each layer constituting the pressure-sensitive adhesive tape (regeneration raw material ratio of each layer constituting the pressure-sensitive adhesive tape) means: the regeneration raw material used in forming each layer accounts for mass of each layer (mass%). The unit (mass%) of the regeneration raw material rate may be expressed as% only.

The regeneration raw material rate of the pressure-sensitive adhesive tape can be determined by the following formula.

Regeneration raw material ratio (%) = [ regeneration raw material ratio of each raw material used in manufacturing the adhesive tape) × (sum of mass of each raw material used in manufacturing the adhesive tape) ]/(total mass of the adhesive tape)

The regeneration material ratio of each layer constituting the pressure-sensitive adhesive tape can be obtained by the following formula.

Regeneration raw material ratio (%) = [ regeneration raw material ratio of each raw material used in manufacturing the layers constituting the adhesive tape) × (sum of mass of each raw material used in manufacturing the layers constituting the adhesive tape)/(mass of the layers constituting the adhesive tape)

In the present specification, the ratio of biomass raw material in the adhesive tape (biomass degree of the adhesive tape) means: the biomass feedstock used in the manufacture of the adhesive tape is a proportion of the total mass of the adhesive tape. The ratio of biomass raw materials in each layer constituting the pressure-sensitive adhesive tape (biomass degree of each layer) means: the biomass raw material used in forming each layer accounts for the mass ratio of the mass of each layer. Specifically, since the raw material manufacturer provides a value of the minimum biomass degree of each biomass-derived raw material, the ratio (mass%) of the biomass raw material in the mass of the adhesive tape and each layer constituting the adhesive tape, that is, the biomass degree can be calculated based on the minimum biomass degree of each biomass-derived raw material provided by the raw material manufacturer and the blending amount of each biomass-derived raw material. The ratio of the biomass raw material may be simply referred to as "biomass degree" or "biomass raw material rate". In addition, the unit (mass%) of biomass may be expressed as% only.

The biomass of the pressure-sensitive adhesive tape can be determined by the following formula.

Biomass degree (%) = [ biomass degree of biomass-derived raw materials used in manufacturing the pressure-sensitive adhesive tape) × (sum of mass of biomass-derived raw materials used in manufacturing the pressure-sensitive adhesive tape)/(total mass of pressure-sensitive adhesive tape)

The biomass content of each layer constituting the pressure-sensitive adhesive tape can be determined by the following formula.

Biomass degree (%) = [ biomass degree of each raw material derived from biomass used in manufacturing the layers constituting the adhesive tape) × (sum of mass of each raw material derived from biomass used in manufacturing the layers constituting the adhesive tape)/(mass of the layers constituting the adhesive tape) ]

The biomass level of the adhesive tape and the layers constituting the adhesive tape can also be calculated by measuring the concentration of radioactive carbon (C14) which is hardly present in the petroleum-derived raw material by accelerator mass analysis. The biomass degree may be within a range as described below as long as the biomass degree is obtained by any one of the above calculation methods.

In the present specification, the ratio of the regenerated raw material and the biomass raw material (referred to as regenerated and biomass raw material ratio) of the pressure-sensitive adhesive tape means: the mass ratio of the regenerated raw material and the biomass raw material in the total mass of the adhesive tape used in manufacturing the adhesive tape. The regeneration and biomass material ratio of each layer constituting the pressure-sensitive adhesive tape means: the mass ratio of the regenerated raw material and the biomass raw material used in forming each layer to the mass of each layer. Specifically, since the raw material manufacturer provides the ratio of the regenerated raw material and the value of the minimum biomass degree of each biomass-derived raw material, the ratio (mass%) of the regenerated raw material and the biomass raw material in the quality of the adhesive tape and each layer constituting the adhesive tape can be calculated based on the minimum regenerated raw material rate of each raw material and the minimum biomass degree of each biomass-derived raw material provided by the raw material manufacturer, and the blending amount of each raw material and each biomass-derived raw material. The unit (mass%) of the biomass material rate to be regenerated is sometimes expressed as% only.

The regeneration of the pressure-sensitive adhesive tape and the biomass material ratio can be obtained by the following formula. In the case where the target raw material is a regenerated raw material and also a biomass raw material, the content of the repetitive component is removed and calculated.

Regeneration of adhesive tape and biomass raw material ratio (%) = { [ regeneration raw material ratio of each raw material used in producing adhesive tape) × (sum of each raw material used in producing adhesive tape) + [ biomass degree of each raw material derived from biomass used in producing adhesive tape) × (sum of each raw material derived from biomass used in producing adhesive tape) }/(total mass of adhesive tape) ]

The regeneration and biomass material ratio of each layer constituting the pressure-sensitive adhesive tape can be determined by the following formula. In the case where the target raw material is a regenerated raw material and also a biomass raw material, the content of the repetitive component is removed and calculated.

Regeneration of each layer constituting the adhesive tape = { [ regeneration raw material ratio of each raw material used when producing the layer constituting the adhesive tape) × (mass of each raw material used when producing the layer constituting the adhesive tape) ] + [ sum of each raw material derived from biomass used when producing the layer constituting the adhesive tape + ((mass of each raw material derived from biomass used when producing the layer constituting the adhesive tape) ] }/(mass of the layer constituting the adhesive tape)

In examples and comparative examples described below, the regeneration raw material rate, the biomass content, the regeneration and biomass raw material rate of the entire pressure-sensitive adhesive tape, and the regeneration raw material rate, the biomass content, the regeneration and biomass raw material rate of each layer constituting the pressure-sensitive adhesive tape are calculated by the above formula.

A. adhesive tape

The adhesive tape of the present invention comprises a substrate, an adhesive layer provided on one or both sides of the substrate, and a release liner provided on the surface of the adhesive layer on at least one side of the substrate, wherein at least the substrate and the release liner each contain a recycled resin, the total thickness of the adhesive tape excluding the release liner is greater than 20 [ mu ] m, and the proportion of recycled material in the adhesive tape is 30 mass% or more.

Fig. 1 to 4 are schematic cross-sectional views showing an example of the pressure-sensitive adhesive tape of the present invention. The pressure-sensitive adhesive tape of the present invention is not limited to the embodiments illustrated in fig. 1 to 4. Fig. 1 to 2 are schematic cross-sectional views showing an example of the pressure-sensitive adhesive tape of the present invention, and show an example of a single-sided pressure-sensitive adhesive tape. The pressure-sensitive adhesive tape 10 illustrated in fig. 1 to 2 includes a base material 1, a pressure-sensitive adhesive layer 2 provided on one surface of the base material 1, and a release liner 3 provided on the surface of the pressure-sensitive adhesive layer 2. In the adhesive tape 10 illustrated in fig. 1 and 2, the base material 1 has a multilayer structure in which a layer A1 (symbol 1a in fig. 1 and 2), a layer A2 (symbol 1b in fig. 1 and 2), and a layer A3 (symbol 1c in fig. 1 and 2) are laminated in this order from the adhesive layer 2 side. The release liner 3 has a single-layer structure in the adhesive tape 10 illustrated in fig. 1. In the pressure-sensitive adhesive tape 10 illustrated in fig. 2, the release liner 3 has a three-layer structure in which a layer B1 (denoted by reference numeral 3a in fig. 2), a layer B2 (denoted by reference numeral 3B in fig. 2), and a layer B3 (denoted by reference numeral 3c in fig. 2) are laminated in this order from the pressure-sensitive adhesive layer 2 side.

Fig. 3 to 4 are schematic cross-sectional views showing an example of the pressure-sensitive adhesive tape of the present invention, and show examples of the double-sided pressure-sensitive adhesive tape. The adhesive tape 10 illustrated in fig. 3 to 4 includes a substrate 1, an adhesive layer 2 provided on one surface of the substrate 1, a release liner 3 provided on the surface of the adhesive layer 2, an adhesive layer 4 provided on the other surface of the substrate 1, and a release liner 5 provided on the surface of the adhesive layer 4. In the adhesive tape 10 illustrated in fig. 3 and 4, the base material 1 has a multilayer structure in which a layer A1 (symbol 1a in fig. 3 and 4), a layer A2 (symbol 1b in fig. 3 and 4), and a layer A3 (symbol 1c in fig. 3 and 4) are laminated in this order from the adhesive layer 2 side. In the adhesive tape 10 illustrated in fig. 3, the release liners 3 and 5 each have a single-layer structure. In the adhesive tape 10 illustrated in fig. 4, the release liners 3 and 5 have a three-layer structure including, in order from the adhesive layer 2 and the adhesive layer 5, a layer B1 (symbols 3a and 5a in fig. 4), a layer B2 (symbols 3B and 5B in fig. 4), and a layer B3 (symbols 3c and 5c in fig. 4).

According to the adhesive tape of the present invention, a high recycling rate can be exhibited in the adhesive tape composition including the release liner. In particular, since the mass of the release liner and the substrate is high in the total mass of the thick adhesive tape, the use of the substrate and the release liner having a high regeneration raw material ratio can further improve the regeneration raw material ratio while making the adhesive tape thick.

Among them, the pressure-sensitive adhesive tape of the present invention preferably has the following structure [ 1a ] or [ 2a ].

[ 2a ] the following multilayer structure: the outermost layer on the pressure-sensitive adhesive layer side is a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less, or a layer having a content of a virgin resin of 50 mass% or more.

The pressure-sensitive adhesive tape of the present invention preferably has the following structure [ 1b ] or [ 2b ].

[ 2b ] a multilayer structure as follows: the outermost layer on the pressure-sensitive adhesive layer side is a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less, or a layer having a content of a virgin resin of 50 mass% or more.

In the adhesive tape of the present invention, the reason why the substrate and/or the release liner have the above-described structure is preferable, respectively, is as follows. The inventors found that: in the pressure-sensitive adhesive tape, if a recycled resin film is used for a base material and a release liner, there are problems such as reduced adhesiveness and reduced appearance. Specifically, if the regeneration raw material rate of the base material and the release liner is increased in the adhesive tape, the base material and the release liner easily contain a large amount of impurities generated by the regeneration method. If the pressure-sensitive adhesive layer is formed on a substrate or a release liner containing a large amount of impurities, defects such as fish eyes, surface irregularities, and foaming tend to occur in the pressure-sensitive adhesive layer in large amounts due to the impurities, and as a result, the adhesive strength varies depending on the position of the surface of the pressure-sensitive adhesive layer, and the adhesive strength of the entire pressure-sensitive adhesive tape decreases. In addition, bubbles and fish eyes generated in the adhesive layer due to the impurities are recognized, and thus the adhesive tape has poor appearance. Among them, when a member used for optical applications requires high transparency and high light transmittance, bubbles and fish eyes present in the adhesive tape prevent light transmission, and thus the appearance is reduced and the optical characteristics are affected.

In addition to improving the recycling rate of the adhesive tape, the adhesive layer is provided on the base material and the release liner, and thus, the occurrence of fish eyes, surface irregularities, bubbles, and the like of the adhesive layer can be prevented, and stable adhesiveness and appearance can be exhibited. The fish eyes, surface irregularities, bubbles (foaming) and the like generated in the adhesive layer are sometimes collectively referred to as "defects".

In order to make a thick gauge, the total thickness of the adhesive tape of the present invention excluding the release liner is preferably greater than 20 μm. The total thickness of the adhesive tape excluding the release liner is preferably more than 20 μm and 300 μm or less, more preferably 30 μm or more and 200 μm or less, and still more preferably 50 μm or more and 150 μm or less, from the viewpoint of exhibiting stable adhesion and also exhibiting a high recycling rate. The "thickness" in the present specification means an average thickness measured by a method based on JIS-Z-1702.

The regeneration raw material rate of the pressure-sensitive adhesive tape of the present invention is preferably 30 mass% or more, more preferably 40 mass% or more, still more preferably 45 mass% or more, and still more preferably 50 mass% or more, from the viewpoint of reducing the environmental load. The regeneration raw material rate of the pressure-sensitive adhesive tape is most preferably 100 mass% or less, and may be 99 mass% or less, or may be 95 mass% or less.

In addition, from the viewpoint of reducing environmental load, the pressure-sensitive adhesive tape of the present invention preferably contains a biomass material. The ratio of the regenerated material and the biomass material (regenerated and biomass material ratio) of the pressure-sensitive adhesive tape of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. By controlling the regeneration and biomass material ratio of the adhesive tape of the present invention within the above-described ranges, a more environmentally friendly adhesive tape can be produced. The regeneration and biomass raw material ratio of the pressure-sensitive adhesive tape is most preferably 100 mass% or less, and may be 99 mass% or less, or 98 mass% or less.

Hereinafter, the components constituting the pressure-sensitive adhesive tape of the present invention and the pressure-sensitive adhesive tape will be described in detail.

1. Substrate material

The base material of the present invention contains a recycled resin. The base material is a layer having at least one surface in contact with the adhesive layer.

(1) Composition of the composition

The base material is made of a resin, but may contain any material such as an additive in addition to the resin. As the base material, a resin film can be used. The content of the resin in the base material (resin film) is preferably 90 mass% or more and 100 mass% or less, more preferably 95 mass% or more and 100 mass% or less, still more preferably 99 mass% or more and 100 mass% or less, and particularly preferably 99.5 mass% or more and 100 mass% or less. In the case where the substrate has a multilayer structure of two or more layers, the content of the resin in the substrate means: the proportion of the resin in the total amount of the substrate as a multilayer structure. The resin constituting the base material includes at least a recycled resin, but may include a virgin resin as needed.

In order to make the regeneration raw material rate of the adhesive tape of the present invention equal to or higher than a predetermined value, the base material preferably contains a regeneration resin as a main component. The content of the regenerated resin in the base material is preferably at least 50 mass%, more preferably at least 60 mass%, still more preferably at least 70 mass%, and still more preferably at least 80 mass%. The content of the regenerated resin in the base material is most preferably 100 mass% or less, and may be 99 mass% or less, 98 mass% or less, or 95 mass% or less. The case where the regenerated resin is a mixture of 2 or more kinds is: the sum of the contents of 2 or more regenerated resins. In the case where the base material has a multilayer structure of two or more layers, the content of the recycled resin in the base material means: the proportion of the regenerated resin in the total amount of the base material as a multilayer structure.

The regenerated resin constituting the base material is not particularly limited, and examples thereof include: recycled polyester resins such as recycled polyethylene terephthalate (recycled PET), recycled polypropylene terephthalate (recycled PTT), recycled polybutylene terephthalate (recycled PBT), recycled polyethylene naphthalate (recycled PEN), and recycled polybutylene naphthalate (recycled PBN); regenerated polyolefin resins such as regenerated polypropylene (regenerated PP) and regenerated polyethylene (regenerated PE); regenerated vinyl chloride resin, regenerated styrene resin, regenerated vinyl ether resin, regenerated polyvinyl alcohol resin, regenerated polyamide resin, regenerated polycarbonate resin, regenerated polysulfone resin, and the like. The number of these may be 1 alone or 2 or more. The base material is preferably a resin film containing 1 or 2 or more kinds of these regenerated resins.

Among the above recycled resins, the recycled polyester resin is preferable from the viewpoint of having a large recycled amount and having strength and flexibility required for the base material, and further preferable is recycled polyethylene terephthalate (recycled PET) or recycled polypropylene terephthalate (recycled PTT), and further preferable is recycled polyethylene terephthalate (recycled PET). That is, the base material is preferably a resin film (polyester film) mainly composed of a recycled polyester resin, and more preferably a resin film (PET film) mainly composed of a recycled polyethylene terephthalate. The recycled polyester resin has, for example, dicarboxylic acid units such as terephthalic acid and isophthalic acid, and glycol units such as ethylene glycol. Since the recycled polyester resin formed from a plastic bottle contains isophthalic acid for controlling crystallinity for improving the appearance of the bottle, the dicarboxylic acid unit of the recycled polyester resin preferably contains 95 to 99.5 mol% of terephthalic acid unit and 0.5 to 5 mol% of isophthalic acid unit.

The above-mentioned regenerated resin is preferably at least one of a chemically regenerated resin and a mechanically regenerated resin in view of low cost and a large amount of regenerated resin which can be obtained by using a general-purpose regeneration method. Among the above-mentioned regenerated resins, the chemically regenerated resin and/or mechanically regenerated resin contained in the base material is preferably a chemically regenerated polyester resin and/or a mechanically regenerated polyester resin.

The regenerated resin is preferably a mechanically regenerated resin, since the regenerated resin is excellent in balance between quality and regeneration cost and can improve the regeneration raw material rate of the adhesive tape at low cost.

The regenerated resin is preferably a chemically regenerated resin. The chemically regenerated resin is less contaminated with impurities in the resin film by the regeneration method of the regenerated resin, and can suppress occurrence of defects in the adhesive layer due to impurities contained in the base material (resin film).

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

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

Examples of polyester resins that can be used as the virgin resin include polyethylene terephthalate (PET) resin, polyethylene naphthalate (PEN) resin, polybutylene terephthalate (PBT) resin, polybutylene naphthalate (PBN) resin, polyethylene 2, 5-furandicarboxylate (PEF) resin, and polypropylene terephthalate. Among them, polyethylene terephthalate (PET) resin is preferable, as is the case with the above recycled resin.

In order to set the regeneration raw material rate to a predetermined value or more, the content of the virgin resin in the base material is preferably 50 mass% or less. Among them, the content is preferably 40 mass% or less, more preferably 30 mass% or less, further preferably 10 mass% or less, further preferably 0 mass% or less, that is, no virgin resin, from the viewpoint of being able to suppress occurrence of defects in the adhesive layer due to impurities contained in the recycled resin, and further improving the recycling raw material rate of the base material.

The substrate preferably contains a biomass material, and more preferably the regenerated resin contains a biomass-derived raw material. The term "recycled resin contains a biomass-derived raw material" means: the structural unit of the regenerated resin includes a structural unit derived from biomass. This is because by containing the raw material derived from biomass in the regenerated resin, a more environmentally friendly substrate can be obtained.

For example, polyester resins are obtained by polycondensation of a dicarboxylic acid and a diol, and the structural unit contains a dicarboxylic acid unit and a diol unit. The polyester resin containing the biomass-derived structural unit can be synthesized by using a biomass-derived raw material in at least one of a dicarboxylic acid and a diol. Examples of the biomass-derived diols include biomass-derived (biomass ethanol) glycols produced from sugar cane, corn, and the like. Examples of biomass-derived carboxylic acids include sebacic acid, azelaic acid, isophthalic acid, and terephthalic acid, which are produced from corn, sugar, wood, and the like.

Therefore, in the case where the recycled resin is a recycled polyester resin, the recycled resin can be made into a recycled biomass polyester resin by including a biomass-derived diol unit and/or a biomass-derived carboxylic acid unit in the recycled polyester resin. Among them, the regenerated resin is preferably regenerated biomass polyethylene terephthalate.

In addition, in the case where the base material contains a virgin resin, the virgin resin preferably contains a biomass-derived raw material, that is, the virgin resin preferably contains a biomass-derived structural unit as a structural unit. When the virgin resin is a polyester resin, the virgin resin can be made into a biomass material by including a biomass-derived diol unit and/or a biomass-derived carboxylic acid unit in the polyester resin. Among them, the virgin resin is preferably virgin biomass polyethylene terephthalate.

In either of the recycled biomass polyester resin and the virgin biomass polyester resin, the dicarboxylic acid units as structural units may be derived entirely from biomass, or may be derived partially from biomass, but are preferably derived entirely from biomass. Similarly, the diol units as structural units of the polyester resin may be derived entirely from biomass, or may be derived partially from biomass, but preferably entirely from biomass.

The biomass content 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 still more preferably 50% by mass or more and 100% by mass or less. The regeneration of the substrate and the biomass raw material ratio are preferably 50 mass% or more and 100 mass% or less, more preferably 70 mass% or more and 92 mass% or less, and still more preferably 90 mass% or more and 100 mass% or less. By adjusting the biomass degree of the base material and the regeneration and biomass raw material ratio to the above ranges, a pressure-sensitive adhesive tape which is more environmentally friendly can be obtained.

The base material is composed of the resin, but may contain any additive in addition to the resin. Examples of the additive include: lubricants (for example, inorganic lubricants such as silica, calcium carbonate, and alumina, organic lubricants such as polystyrene resin, polymethyl methacrylate resin, silica gel, and acrylic resin, or a combination thereof), electrostatic adhesion agents (for example, metal salts containing an alkali metal or an alkaline earth metal such as sodium hydroxide and potassium hydroxide, and metal salts containing an aliphatic carboxylic acid), metal catalysts (for example, antimony, germanium, titanium, and a mixture thereof), pigments, antioxidants, antistatic agents, UV absorbers, stabilizers, and degradable materials (for example, biopolymers such as starch, cellulose, chitin, polylactic acid, and polyglycolic acid, and natural materials such as natural rubber).

(2) Traits (3)

The thickness of the pressure-sensitive adhesive tape other than the release liner is not particularly limited as long as the thickness is within a predetermined range, and is preferably greater than 9 μm, and among them, it is preferably 12 μm or more and 250 μm or less, more preferably 12 μm or more and 200 μm or less, and still more preferably 16 μm or more and 150 μm or less. The reason for this is that, by setting the thickness of the base material to the above-described range, the adhesive tape can be increased in thickness while having strength for supporting the adhesive layer and flexibility required for the adhesive tape. The term "thickness of the substrate" when the substrate has a multilayer structure means: the sum of the thicknesses of the layers constituting the multilayer structure.

The substrate may have a single-layer structure or a multilayer structure. Among them, the above-mentioned base material preferably has the following structure [ 1a ] or [ 2a ] from the viewpoint of obtaining a thick adhesive tape.

[ 2a ] a multilayer structure as follows: the outermost layer on the adhesive layer side is a layer in which the content of the regenerated resin is 50 mass% or more and 100 mass% or less and the content of the mechanically regenerated resin is 95 mass% or less, or a layer in which the content of the virgin resin is 50 mass% or more.

The reason why the substrate preferably has the above-mentioned structure [ 1a ] or [ 2a ] is as follows. The mechanically regenerated resin in the base material contains impurities due to its regeneration method, and the more the mechanically regenerated resin is, the more the impurities the base material contains. In this case, the pressure-sensitive adhesive layer in contact with the base material may be defective due to the amount of the impurity present in the outermost layer of the base material. Specifically, the adhesive layer in contact with the substrate may cause defects due to impurities in the substrate, and may cause defects such as a decrease in adhesion due to uneven adhesion, and poor appearance. In contrast, when the pressure-sensitive adhesive layer is provided on the substrate by providing the substrate with the single-layer or multi-layer structure, the pressure-sensitive adhesive layer is less likely to come into contact with impurities contained in the substrate, and thus the occurrence of the above-described defects can be suppressed.

The layer in which the content of the regenerated resin is 50 mass% or more and 100 mass% or less and the content of the mechanically regenerated resin is 95 mass% or less means that: the content of the regenerated resin in the layer (resin film) may be 50 mass% or more and 100 mass% or less, and the content of the mechanically regenerated resin in the layer (resin film) may be 95 mass% or less. Examples of such layers include, but are not limited to, the following layers L1 to L3.

Layer L1: the mechanically regenerated resin content in the layer is 50 mass% or more and 95 mass% or less;

Layer L2: the content of the chemically regenerated resin in the layer is 50 mass% or more and 100 mass% or less;

Layer L3: the layer contains less than 50 mass% of mechanically regenerated resin, less than 50 mass% of chemically regenerated resin, and the sum of the contents of mechanically regenerated resin and chemically regenerated resin is 50 mass% or more.

The layer L1 may be a mechanically regenerated resin having a content of 50 mass% or more and 95 mass% or less, and the content is preferably 60 mass% or more and 95 mass% or less, more preferably 70 mass% or more and 95 mass% or less, and still more preferably 80 mass% or more and 90 mass% or less. The mechanically regenerated resin has an excellent balance between quality and regeneration cost, and can improve the regeneration raw material rate of the adhesive tape at low cost, but contains impurities due to its regeneration method. Even if the layer (resin film) having the content of the mechanically regenerated resin in the above range contains impurities, the occurrence of defects in the adhesive layer due to the impurities can be suppressed, and a high regeneration raw material rate can be achieved. In the case where the layer L1 contains 2 or more mechanically regenerated resins, the content of the mechanically regenerated resins means: 2 or more. The resin constituting the layer L1 may contain a chemically regenerated resin and/or a virgin resin in addition to the mechanically regenerated resin.

The content of the chemically regenerated resin in the layer L2 is preferably not less than 50% by mass and not more than 100% by mass, more preferably not less than 70% by mass, still more preferably not less than 80% by mass, still more preferably not less than 90% by mass, and particularly preferably not more than 100% by mass. Since the chemically regenerated resin has no contamination or trace amount of contamination of impurities due to the regeneration method of the regenerated resin, the use of a layer (resin film) having a content of the chemically regenerated resin within the above range can suppress the occurrence of defects in the adhesive layer caused by the above impurities, and can realize a high regeneration raw material rate. In the case where the layer L2 contains 2 or more kinds of chemically regenerated resins, the content of the chemically regenerated resins means: 2 or more. The resin constituting the layer L2 may contain a mechanically regenerated resin and/or a virgin resin in addition to the chemically regenerated resin.

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

In the case where the substrate has a single-layer structure, the substrate is preferably any one of the layers L1 to L3. Among them, layer L1 or layer L2 is preferable, and layer L2 is more preferable, in view of low cost and high regeneration raw material rate.

In the case where the substrate has a multilayer structure, the substrate is only: at least one outermost layer (the outermost layer on the adhesive layer side) may be a layer having a content of the regenerated resin of 50 mass% or more and 100 mass% or less and a content of the mechanically regenerated resin of 95 mass% or less, or a layer having a content of the virgin resin of 50 mass% or more. The multilayer structure may have a two-layer structure or a three-layer or more structure. In the case where the substrate has a multilayer structure, the layers constituting the substrate are referred to as a layer A1, a layer A2, a layer A3, … (hereinafter omitted) in the adhesive tape of the present invention in this order from the adhesive layer side.

The substrate of the multilayer structure is preferably: the outermost layers of the two are layers each having a regenerated resin content of 50 mass% or more and 100 mass% or less and a mechanically regenerated resin content of 95 mass% or less, or a layer having a virgin resin content of 50 mass% or more. By providing the substrate with such a multilayer structure, in the case where the pressure-sensitive adhesive tape of the present invention is a double-sided pressure-sensitive adhesive tape, occurrence of defects due to impurities in the substrate can be suppressed in the pressure-sensitive adhesive layers provided on the two outermost layers of the substrate. In addition, even when the adhesive tape of the present invention is a single-sided adhesive tape, the occurrence of defects due to impurities in the substrate can be suppressed in the adhesive layer provided on one outermost layer of the substrate and the other functional layer provided on the other outermost layer of the substrate.

The substrate of the multilayer structure is preferably: the layer other than at least one outermost layer (the outermost layer on the adhesive layer side) is a layer in which the content of the mechanically regenerated resin is 50 mass% or more and 100 mass% or less. Wherein the layers other than the two outermost layers are preferably: a layer in which the content of the mechanically regenerated resin is 50 mass% or more and 100 mass% or less. The layer other than the outermost layer is a layer mainly composed of a mechanically regenerated resin, whereby occurrence of defects due to impurities contained in the base material can be suppressed, and the regeneration raw material rate of the entire base material can be improved at low cost.

In the case where the base material has a two-layer structure of the layer A1 and the layer A2 adjacent to the layer A1, at least one layer (the layer on the adhesive layer side) may be a layer selected from the layers L1 to L3, and the layer A1 and the layer A2 are preferably a layer selected from the layers L1 to L3, respectively. In this case, the layer A1 and the layer A2 may be the same or different.

When the base material has a three-layer structure including a layer A1, a layer A2, and a layer A3 in this order from the adhesive layer side, the layer A1 and the layer A3 are each a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less, or a layer having a content of a virgin resin of 50 mass% or more, and the layer A2 is preferably a layer having a content of a mechanically regenerated resin of 50 mass% or more and 100 mass% or less. By forming the base material into such a three-layer structure, both the effect caused by the outermost layer and the effect caused by the layer other than the outermost layer can be achieved. Examples of such a three-layer structure include the following structures (layer A1/layer A2/layer A3), but are not limited to these structures.

A layer having a virgin resin content of 50 mass% or more, a layer having a mechanically regenerated resin content of 50 mass% or more and 100 mass% or less, and a layer having a virgin resin content of 50 mass% or more;

A layer in which the content of the chemically regenerated resin is 50 mass% or more and 100 mass% or less, a layer in which the content of the mechanically regenerated resin is 50 mass% or more and 100 mass% or less, and a layer in which the content of the chemically regenerated resin is 50 mass% or more;

A layer having a mechanically regenerated resin content of 50 mass% or more and 95 mass% or less, a layer having a mechanically regenerated resin content of 50 mass% or more and 100 mass% or less, and a layer having a mechanically regenerated resin content of 50 mass% or more and 95 mass% or less.

In the multilayer structure, the layer having a mechanically regenerated resin content of 50 mass% or more and 95 mass% or less and the layer having a chemically regenerated resin content of 50 mass% or more and 100 mass% or less can be the same as the layer L1 and the layer L2 described above.

In the multilayer structure, the layer containing 50 mass% or more and 100 mass% or less of the mechanically regenerated resin may contain the largest amount of mechanically regenerated resin, and the content is more preferably 70 mass% or more, still more preferably 90 mass% or more, and particularly preferably 100 mass% or less. This is because a low cost and a high regeneration raw material rate can be achieved.

The layer containing 50 mass% or more and 100 mass% or less of the virgin resin may contain the largest amount of virgin resin, and the content is more preferably 80 mass% or more, still more preferably 90 mass% or more, and particularly preferably 100 mass% or less. This is because a low cost and a high regeneration raw material rate can be achieved.

In the substrate having a multilayer structure, the thickness of the outermost layer is not particularly limited, and is preferably in the range of 1 μm to 100 μm, more preferably in the range of 3 μm to 75 μm, and still more preferably in the range of 5 μm to 50 μm, for example. This is because defects in the adhesive layer can be suppressed, and the adhesive property can be stabilized and the appearance can be improved.

In the substrate having a multilayer 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 still more preferably in the range of 10 μm to 75 μm, for example. Among these, when the content of the mechanically regenerated resin is 50 mass% or more and 100 mass% or less, the layer other than the outermost layer is preferably a layer whose thickness is in the above range, so that a high regeneration raw material rate can be achieved at low cost.

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

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

The substrate is preferably transparent. In particular, when the pressure-sensitive adhesive tape of the present invention is used for optical applications, the total light transmittance of the substrate in visible light is preferably 90% or more, more preferably 92% or more, and still more preferably 93% or more, for example. The haze of the substrate in visible light is preferably 2% or less, more preferably 1% or less, and still more preferably 0.8% or less. This is because the substrate can be made to have less impurities due to the recycled resin by causing the substrate to exhibit the total light transmittance and/or haze. The total light transmittance and haze described in the present specification are measured according to JIS K7361-1.

(3) Forming method

The substrate can be formed by a conventionally known film forming method, and the method is not particularly limited, and can be manufactured by extrusion film forming by a T-die method, for example. In the case where the substrate has a multilayer structure, the substrate 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 base material can be produced by the methods disclosed in, for example, international publication No. 2022/071440, japanese patent application laid-open No. 2021-172818, japanese patent application laid-open No. 2021-311668, etc.

2. Release liner

The release liner of the present invention comprises a recycled resin. The release liner is provided on the surface of the adhesive layer, that is, on the surface of the adhesive layer opposite to the surface on the substrate side. In the pressure-sensitive adhesive tape of the present invention, when the pressure-sensitive adhesive layer is provided on both sides of the substrate, the release liner may be provided on the surface of the pressure-sensitive adhesive layer on at least one side of the substrate, or may be provided on the surface of each pressure-sensitive adhesive layer provided on both sides of the substrate. When the release liners are provided on the surfaces of the two adhesive layers, the release liner on one side and the release liner on the other side may be the same or may be different in structure and composition.

(1) Composition of the composition

The release liner is made of a resin, but may contain any material such as an additive in addition to the resin. As the release liner, a resin film can be used. 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 still more preferably 99% by mass or more and 100% by mass or less. In the case where the release liner has a multilayer structure of two or more layers, the content of the resin in the release liner means: the proportion of the resin in the total amount of the release liner as a multilayer structure. The resin constituting the release liner includes at least a recycled resin, but may include a virgin resin as needed.

In order to make the regeneration raw material rate of the adhesive tape of the present invention equal to or higher than a predetermined value, the release liner preferably contains a regeneration resin as a main component. The content of the regenerated resin in the release liner may be 50 mass% or more, and among them, 80 mass% or more, more preferably 85 mass% or more, and still more preferably 90 mass% or more is preferable. The upper limit of the proportion of the regenerated resin is most preferably 100 mass%, and the upper limit may be 99 mass% or 98 mass%. By setting the content of the regenerated resin in the release liner within the above range, the regeneration raw material rate of the adhesive tape of the present invention can be further improved. The case where the regenerated resin is a mixture of 2 or more kinds is: the sum of the contents of 2 or more regenerated resins. In the case where the release liner has a multilayer structure of two or more layers, the proportion of the recycled resin in the release liner means: the proportion of the regenerated resin in the total amount of the release liner as a multilayer structure.

The regenerated resin constituting the release liner is not particularly limited, and the regenerated resin exemplified in the item "1. Substrate" can be used. The regenerated resin may be used alone or in combination of 2 or more. Among them, recycled polyester resin is preferable, and recycled polyethylene terephthalate (recycled PET) is more preferable, from the viewpoint of having a large amount of recycling and having strength and flexibility required for release liners.

The regenerated resin constituting the release liner is preferably at least one of a chemically regenerated resin and a mechanically regenerated resin, since a low-cost and large-scale regenerated resin can be obtained by using a general-purpose regeneration method. Among these, the above-mentioned chemically and/or mechanically regenerated resins are preferably chemically and/or mechanically regenerated polyester resins, and among the above-mentioned exemplified regenerated resins, chemically and/or mechanically regenerated polyethylene terephthalate (regenerated PET) is preferable.

The regenerated resin constituting the release liner is preferably a mechanically regenerated resin in terms of being excellent in balance between quality and regeneration cost and capable of improving the regeneration raw material rate of the adhesive tape at low cost.

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

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

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

The release liner preferably contains a biomass material, and the regenerated resin and/or the virgin resin contained in the release liner more preferably contains a biomass-derived raw material. This is because, in addition to the regeneration raw material rate of the release liner, the biomass level can be improved, and a more environmentally friendly adhesive tape can be obtained.

When the recycled resin and/or the virgin resin constituting the release liner is a polyester resin, the polyester resin is a biomass polyester resin by including a biomass-derived diol unit and/or a biomass-derived carboxylic acid unit. Among them, the polyester resin is preferably a biomass polyethylene terephthalate.

The degree of biomass 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 still more preferably 90% by mass or more and 100% by mass or less. The regeneration and biomass material ratio of the release liner is preferably 70 mass% or more and 100 mass% or less, more preferably 80 mass% or more and 100 mass% or less, and still more preferably 95 mass% or more and 100 mass% or less. When the release liner has a multilayer structure, the biomass degree and the regeneration and biomass material ratio are values of the whole multilayer structure.

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

(2) Traits (3)

The thickness of the release liner is not particularly limited as long as the regeneration raw material rate of the pressure-sensitive adhesive tape of the present invention can be set to a predetermined value or more, and is preferably 10 μm or more and 200 μm or less, more preferably 12 μm or more and 100 μm or less, and still more preferably 12 μm or more and 50 μm or less, for example. The case where the release liner has a multilayer structure means that: and (3) summing the film thicknesses of the layers.

The release liner may have a single-layer structure or a multilayer structure. Among them, the release liner preferably has the following structure [ 1b ] or [ 2b ].

[ 2b ] a multilayer structure as follows: the outermost layer of the adhesive layer is a layer having a regenerated resin content of 50 mass% or more and 100 mass% or less and a mechanically regenerated resin content of 95 mass% or less, or a layer having a virgin resin content of 50 mass% or more.

By providing the release liner with the structure of [ 1b ] or [ 2b ], occurrence of defects in the adhesive layer caused by impurities contained in a layer that provides a contact surface with the adhesive layer of the release liner can be suppressed, and reduction in adhesion due to adhesion unevenness can be suppressed.

A layer having a content of the regenerated resin of 50 mass% or more and 100 mass% or less and a content of the mechanically regenerated resin of 95 mass% or less may be used as long as the content of the regenerated resin in the layer (resin film) is 50 mass% or more and 100 mass% or less and the content of the mechanically regenerated resin in the layer (resin film) is 95 mass% or less. Examples of such layers include the following layers M1 to M3.

Layer M1: the mechanically regenerated resin content in the layer is 50 mass% or more and 95 mass% or less;

Layer M2: the content of the chemically regenerated resin in the layer is 50 mass% or more and 100 mass% or less;

Layer M3: the layer contains less than 50 mass% of mechanically regenerated resin, less than 50 mass% of chemically regenerated resin, and the sum of the contents of mechanically regenerated resin and chemically regenerated resin is 50 mass% or more.

Details of the layers M1, M2, and M3 are the same as those of the layers L1, L2, and L3 described in the "1. Substrate (2) property" item, and therefore, descriptions thereof are omitted here.

In the case where the release liner has a single-layer structure, the release liner is preferably any one of the layers M1 to M3. Among them, the layer M1 or the layer M2 is preferable, and the layer M2 is more preferable, in view of low cost and high regeneration raw material rate.

In the case where the release liner has a multilayer structure, the release liner is only: at least one outermost layer (the outermost layer on the adhesive layer side) may be a layer having a content of the regenerated resin of 50 mass% or more and 100 mass% or less and a content of the mechanically regenerated resin of 95 mass% or less, or a layer having a content of the virgin resin of 50 mass% or more. The multilayer structure may have a two-layer structure or a three-layer or more structure. Each layer constituting the release liner as a multilayer structure is referred to as a layer B1, a layer B2, a layer B3, … (omitted below) in the adhesive tape of the present invention in this order from the adhesive layer side.

The release liner of the multilayer structure is preferably: the outermost layer on the pressure-sensitive adhesive layer side and the outermost layer on the side opposite to the pressure-sensitive adhesive layer side are each a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less, or a layer having a content of a virgin resin of 50 mass% or more. By the contact between the outermost layer on the pressure-sensitive adhesive layer side of the release liner and the pressure-sensitive adhesive layer and the contact between the outermost layer on the opposite side of the release liner from the pressure-sensitive adhesive layer side and the pressure-sensitive adhesive layer when the pressure-sensitive adhesive tape is formed into a roll shape, occurrence of defects in the pressure-sensitive adhesive layer due to impurities contained in the release liner can be suppressed.

The release liner of the multilayer structure is preferably: the outermost layer on the pressure-sensitive adhesive layer side and the layer other than the outermost layer on the opposite side from the pressure-sensitive adhesive layer side are layers containing 50 to 100 mass% of the mechanically regenerated resin. By using the layer other than the two outermost layers as a layer containing the mechanically regenerated resin as a main component, the regeneration raw material rate of the entire release liner can be improved.

The release liner preferably has a three-layer structure including the layer B1, the layer B2, and the layer B3 in this order from the adhesive layer side. In the above three-layer structure, the layers B1 and B3 are preferably each: a layer containing 50 mass% or more and 100 mass% or less of a regenerated resin and 95 mass% or less of a mechanically regenerated resin, or a layer containing 50 mass% or more of a virgin resin. In the above three-layer structure, the layer B2 is preferably a layer having a mechanically regenerated resin content of 50 mass% or more and 100 mass% or less. By forming the release liner into such a three-layer structure, both the effect caused by the outermost layer and the effect caused by the layer other than the outermost layer can be achieved. Examples of such a three-layer structure include the following structures (layer B1/layer B2/layer B3), but are not limited to these structures.

The details of the layers constituting the multilayer structure, in which the content of the mechanically regenerated resin is 50 mass% or more and 95 mass% or less, and the content of the chemically regenerated resin is 50 mass% or more and 100 mass% or less, can be the same as those described in the above-mentioned layer M1 and layer M2, and the above-mentioned "1. Substrate (2) property" item.

The details of the layer constituting the multilayer structure, in which the content of the mechanically regenerated resin is 50 mass% or more and 100 mass% or less, can be the same as those described in the above item "1. Substrate (2) property".

The details of the layer constituting the multilayer structure, in which the content of the virgin resin is 50 mass% or more and 100 mass% or less, can be the same as those described in the above item "1. Substrate (2) property".

The thickness of the outermost layer and the thickness of the layer other than the outermost layer in the release liner of the multilayer structure may be the same as the thickness of the outermost layer and the thickness of the layer other than the outermost layer in the substrate of the multilayer structure described in the item "1. Substrate (2) property".

In order to impart easy peelability, the release liner has a laminate film or a coating film containing a release agent on one side (the surface on the pressure-sensitive adhesive layer side). As the release agent, for example, a silicone release agent, a fluorine release agent, a long-chain alkyl release agent, and the like are preferably used.

(3) Forming method

The release liner can be formed by producing a resin film by the same method as the method for forming a base material described in the above "1. Method for forming a base material (3)", and subjecting the surface to a mold release treatment. In the case where the release liner has a multilayer structure, a laminate of resin films is produced by multilayer extrusion film formation by a T-die method, and the surface is subjected to a mold release treatment. The method for producing the recycled polyester resin film used for the release liner can be produced by the methods disclosed in, for example, international publication No. 2022/071440, japanese patent application laid-open No. 2021-172818, japanese patent application laid-open No. 2021-311668, etc.

The release treatment to be performed on the surface of the release liner is not particularly limited, and examples of the method include a method of laminating and coating various release agents for release liners of adhesive tapes.

3. Adhesive layer

The adhesive layer in the present invention is provided on one or both sides of the substrate and is composed of an adhesive. In the case where the pressure-sensitive adhesive tape of the present invention is a double-sided pressure-sensitive adhesive tape, the composition and properties of the pressure-sensitive adhesive layer on one side of the substrate and the pressure-sensitive adhesive layer on the other side of the substrate may be the same or different.

(1) Composition of the composition

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer may be a pressure-sensitive adhesive (petroleum-based pressure-sensitive adhesive) composed of a conventional petroleum-derived raw material, may be a pressure-sensitive adhesive containing a renewable raw material (renewable pressure-sensitive adhesive), or may be a pressure-sensitive adhesive containing a biomass-derived raw material (biomass pressure-sensitive adhesive). Among them, from the viewpoint of environmental friendliness, a binder containing a renewable raw material is preferable, and a binder containing a renewable raw material and a biomass-derived raw material is more preferable.

The pressure-sensitive adhesive layer may or may not contain a recycling material, but the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer preferably contains a recycling material in order to achieve a high recycling material rate. The regeneration raw material rate of the pressure-sensitive 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 still more preferably 80% by mass or more and 100% by mass or less.

In addition, from the viewpoint of further improving the biomass material ratio of the pressure-sensitive adhesive tape of the present invention, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is preferably a biomass pressure-sensitive adhesive containing a biomass-derived raw material. The biomass content of the pressure-sensitive 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 still more preferably 80% by mass or more and 100% by mass or less. From the viewpoint of obtaining a more environmentally friendly adhesive tape, the regeneration and biomass raw material ratio of the adhesive layer is preferably 0 mass% or more and 100 mass% or less, more preferably 70 mass% or more and 100 mass% or less, and still more preferably 90 mass% or more and 100 mass% or less.

The recycling rate, biomass fraction, and recycling and biomass fraction of the pressure-sensitive adhesive layer can be appropriately adjusted by selecting the type of monomer of the polymer (base polymer) constituting the main component contained in the pressure-sensitive adhesive layer, the type of tackifying resin that can be optionally added to the pressure-sensitive adhesive layer, and the like.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer contains at least a polymer (base polymer) as a main component, and if necessary, a tackifying resin and a crosslinking agent. Examples of such adhesives include acrylic adhesives containing an acrylic polymer as a main component, rubber adhesives containing a rubber polymer as a main component, polyester adhesives containing a polyester polymer as a main component, urethane adhesives containing a urethane polymer as a main component, vinyl alkyl ether adhesives, silicone adhesives, polyamide adhesives, fluorine adhesives, and epoxy adhesives. The binder may be used alone or in combination of at least 2 kinds.

Among them, from the viewpoint of adhesion, the adhesive constituting the adhesive layer is preferably an acrylic adhesive, a urethane adhesive, a rubber adhesive, or a polyester adhesive, and from the viewpoint of enabling higher adhesion, an acrylic adhesive is further preferred. The adhesive is preferably a polyester adhesive from the viewpoint of being capable of achieving a high recycling raw material rate and biomass, and from the viewpoint of being capable of returning to an oligomer or a monomer by depolymerization and facilitating recycling of the adhesive tape itself of the present invention.

(Acrylic Polymer)

The acrylic polymer (acrylic polymer) which is the main component of the acrylic adhesive is composed of a (meth) acrylate alone or a copolymer of a (meth) acrylate and other monomers. Examples of the (meth) acrylic acid ester monomer used for the production of the acrylic acid 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 1 or 2 or more of these monomers are used. Among them, (meth) acrylic acid esters having an alkyl group having 1 to 12 carbon atoms are preferable, and (meth) acrylic acid esters having an alkyl group having 4 to 8 carbon atoms are more preferable, and at least one of n-butyl acrylate and 2-ethylhexyl acrylate is preferable in terms of easy securing of adhesion to an adherend and excellent cohesive force. In the present specification, the term "(meth) acrylate" refers to a combination of acrylate and methacrylate.

The amount of the (meth) acrylate monomer contained in the total amount of the monomers used in the production of the acrylic polymer (in the structural unit of the acrylic polymer) is preferably 80 to 99 mass%, more preferably 85 to 98.5 mass%, and 90 to 97.5 mass%, and adhesion to an adherend is easily ensured and the cohesive force is excellent, and thus is more preferable. In addition, if the (meth) acrylate monomer contains 30 mass% or more of n-butyl acrylate, the adhesion and heat resistance are excellent, and thus preferable.

The above acrylic polymer contains a (meth) acrylate monomer in a structural unit, and may further contain a highly polar vinyl monomer in a structural unit. Examples of the high-polarity vinyl monomer include a vinyl monomer having a hydroxyl group, a vinyl monomer having a carboxyl group, a vinyl monomer having an amide group, and other high-polarity vinyl monomers other than these. Among them, it is preferable that the vinyl monomer contains 1 or 2 or more kinds of 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.

As the vinyl monomer having a hydroxyl group, for example, a hydroxyl group-containing (meth) acrylate such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate can be used.

As the vinyl monomer having a carboxyl group, acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth) acrylic acid dimer, crotonic acid, and the like can be used, and among them, acrylic acid is preferably used.

As the vinyl monomer having an amide group, N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, N-dimethylacrylamide, and the like can be used.

Examples of the other highly polar vinyl monomer include sulfonic acid group-containing monomers such as vinyl acetate, ethylene oxide-modified succinic acid acrylate, and 2-acrylamide-2-methylpropanesulfonic acid, in addition to the above-mentioned monomers.

The content of the high-polarity vinyl monomer is preferably in the range of 1 to 20 mass%, more preferably in the range of 2 to 15 mass%, and even more preferably in the range of 2.5 to 10 mass% of the total amount of monomers constituting the acrylic polymer (structural units of the acrylic polymer). When the high-polarity vinyl monomer is contained in the above range, adhesion to an adherend is easily ensured, and the cohesive force is excellent, which is more preferable.

The molecular weight of the acrylic polymer is preferably 50 to 120 tens of thousands, more preferably 50 to 100 tens of thousands, in terms of standard polystyrene, as measured by Gel Permeation Chromatography (GPC). When the weight average molecular weight (Mw) of the acrylic polymer is within the above range, the film adhesive layer is likely to exhibit sufficient adhesiveness and heat resistance.

The weight average molecular weight of the acrylic polymer mentioned above means: a value calculated in terms of standard polystyrene, measured by gel permeation chromatography (GPC method). Specifically, the weight average molecular weight can be measured using a GPC apparatus (HLC-8320 GPC) manufactured by Tosoh corporation under the following conditions.

Sample concentration: 1.0 mass% (tetrahydrofuran solution)

Sample injection amount: 100 mu L

Eluent: tetrahydrofuran (THF)

Flow rate: 0.8 mL/min

Measuring temperature: 40 DEG C

The column comprises: TSKgel, GMHHR-H (S) 2 roots

Protective column: TSKguradcolum HHR (S)

A detector: differential refractometer

Weight average molecular weight of standard polystyrene: 1 ten thousand to 2000 ten thousand (manufactured by Tosoh Co., ltd.)

The acrylic polymer can be produced by a conventional polymerization method such as a solution polymerization method, an emulsion polymerization method, and an ultraviolet irradiation polymerization method.

(Polyester Polymer)

The polyester polymer as a main component of the polyester adhesive is a polymer containing a polycarboxylic acid and a polyhydric alcohol as a polymerization component, the polymer having a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol.

Polycarboxylic acids-

The structural units derived from polycarboxylic acids may be derived from petroleum or biomass. In addition, the structural units derived from polycarboxylic acids may also be derived from regeneration.

Examples of the polycarboxylic acid forming the structural unit derived from a polycarboxylic acid include dicarboxylic acids and dicarboxylic acids having a structure of three or more members. Examples of dicarboxylic acids include: aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, benzyl malonic acid, diphenic acid, 4' -oxydibenzoic acid, and naphthalene dicarboxylic acid (e.g., 1, 8-naphthalene dicarboxylic acid, 2, 3-naphthalene dicarboxylic acid, and 2, 7-naphthalene dicarboxylic acid); aliphatic dicarboxylic acids such as malonic acid, dimethylmalonic acid, succinic acid, methylsuccinic acid, glutaric acid, adipic acid, dimethyladipic acid, trimethyladipic acid, pimelic acid, 2-dimethylglutaric acid, 1, 3-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; etc. Examples of the tri-or higher carboxylic acid include trimellitic acid, pyromellitic acid, adamantane tricarboxylic acid, and trimesic acid. They may be used singly or in combination of 2 or more.

Among them, from the viewpoint of imparting tackiness, the polyester polymer preferably contains a structural unit derived from an aliphatic dicarboxylic acid, more preferably contains a structural unit derived from an aliphatic dicarboxylic acid having 8 or less carbon atoms. Examples of the aliphatic dicarboxylic acid having 8 or less carbon atoms include: straight-chain 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 a side chain alkyl group such as methylsuccinic acid, 2-dimethylglutaric acid, 1, 3-dimethylglutaric acid, and dimethyladipic acid, and sulfur-containing dicarboxylic acids such as thiodipropionic acid; unsaturated group-containing aliphatic dicarboxylic acids such as fumaric acid, maleic acid and itaconic acid. They may be used singly or in combination of 2 or more.

The polyester polymer preferably contains a structural unit derived from a linear aliphatic dicarboxylic acid, from the viewpoint of excellent adhesion to various adherends and small changes in the initial and aged adhesion, and from the viewpoint of excellent adhesion to films and small aged changes in the adhesion, a structural unit derived from adipic acid is preferred. The content of the structural unit derived from the aliphatic dicarboxylic acid 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 still more preferably 75 mol% or more and 98 mol% based on the structural unit derived from the polycarboxylic acid.

In addition, as the formation of the polycarboxylic acid derived from the polycarboxylic acid structural unit of the structure unit, from the view point of reducing the crystallinity of the polyester polymer, preferably contains an aromatic dicarboxylic acid, more preferably contains phthalic acid, isophthalic acid, 1, 8-naphthalene two formic acid, 2, 3-naphthalene two formic acid asymmetric aromatic two carboxylic acid. The content of the structural unit derived from the aromatic dicarboxylic acid is preferably 1 to 40 mol%, more preferably 2 to 30 mol% based on the structural unit derived from the polycarboxylic acid in order to maintain the initial adhesion and tackiness at a high level.

Polyol-containing compositions

Structural units derived from polyols may be derived from petroleum or biomass. In addition, structural units derived from polyols may also be derived from regeneration. The polyhydric alcohol constituting the structural unit derived from a polyhydric alcohol includes a polyhydric alcohol having two or more members. They may contain 2 or more alone or in combination. Among them, a glycol is preferably contained. Examples of the diol include: aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1, 3-propanediol, 2, 4-dimethyl-2-ethylhexyl-1, 3-diol, 2-methyl-1, 3-propanediol, 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, 4-trimethyl-1, 6-hexanediol, dimer diols derived from oleic acid, erucic acid, and the like, and hydrogenated dimer diols; alicyclic diols such as 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol, spirocyclic diol, tricyclodecanediol, adamantanediol, and 2, 4-tetramethyl-1, 3-cyclobutanediol; aromatic diols such as 4,4' -thiodiphenol, 4' -methylenediphenol, 4' -dihydroxydiphenyl, o-, m-and p-dihydroxybenzene, 2, 5-naphthalene diol, p-xylene diol, and ethylene oxide adducts and propylene oxide adducts thereof; fatty acid esters derived from castor oil; glycerol monostearate, and the like.

Among these, the polyhydric alcohol constituting the structural unit derived from the polyhydric alcohol preferably contains at least one of an aliphatic diol and an alicyclic diol, and more preferably contains an aliphatic diol, from the viewpoint of excellent reactivity. The aliphatic diol may have a linear structure or a hydrocarbon group in a side chain, and is preferably a linear structure having 2 to 18 carbon atoms, and from the viewpoint of high adhesion as a film, it is preferably an aliphatic diol having 4 or less carbon atoms. Specifically, structural units derived from ethylene glycol, 1, 3-propanediol, and 1, 4-butanediol are exemplified, and structural units derived from ethylene glycol are particularly preferable.

In addition, from the viewpoint of little change in adhesion to various adherends and initial and aged adhesion, the polyhydric alcohol constituting the structural unit derived from the polyhydric alcohol preferably contains at least one selected from ethylene glycol, 2-methyl-1, 3-propanediol and neopentyl glycol, and particularly preferably has ethylene glycol and/or neopentyl glycol. The content of the structural unit derived from at least one selected from the group consisting of ethylene glycol, 2-methyl-1, 3-propanediol and neopentyl glycol is preferably 70mol% or more, more preferably 80mol% or more, and still more preferably 90mol% or more, based on the structural unit derived from the polyol. The upper limit is 100mol%.

Further, from the viewpoint of increasing branching points in the polymer, the polyol constituting the structural unit derived from the polyol may contain a polyol having three or more members. Examples of the three or more polyhydric alcohols include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerol, trimethylolpropane, trimethylolethane, 1,3, 6-hexanetriol, and adamantanetriol. The content of the structural unit derived from the three-way or higher polyol is preferably 10 mol% or less, and particularly preferably 0.1 to 5 mol% based on the structural unit derived from the polyol.

The proportion (composition ratio) of the structural units derived from each component of the polyester polymer can be determined by a known method using NMR, for example, 1H-NMR measurement (proton nuclear magnetic resonance spectroscopy measurement) at a resonance frequency of 400MHz, 13C-NMR measurement (carbon nuclear magnetic resonance spectroscopy measurement), or the like. The proportion of the structural units derived from each component of the polyester polymer can be calculated from the blending ratio in the composition containing the polyhydric alcohol and the polycarboxylic acid at the time of producing the polyester polymer.

The polyester polymer may have, for example, a structural unit derived from a compound having both a carboxyl group and a hydroxyl group in the molecule (for example, lactic acid or the like), in addition to a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol.

The blending ratio of the polycarboxylic acid to the polyol in the production of the polyester polymer is preferably 1 to 2 equivalents, more preferably 1.1 to 1.7 equivalents, based on 1 equivalent of the polycarboxylic acid.

The polyester polymer can be produced, for example, by subjecting a polycarboxylic acid and a polyol to polycondensation reaction by a known method in the presence of a catalyst. The polyester polymer is obtained by polycondensation reaction of a polycarboxylic acid with a polyol, and thus has a structural unit derived from the polycarboxylic acid and a structural unit derived from the polyol. In the polycondensation reaction, the esterification reaction or the transesterification reaction is first performed and then the polycondensation reaction is performed, but the polycondensation reaction may be performed only by the esterification reaction or the transesterification reaction when a high molecular weight is not required.

(Tackifying resin)

The pressure-sensitive adhesive may contain 1 or 2 or more kinds of tackifying resins in addition to the base polymer as a main component in order to improve the adhesiveness of the pressure-sensitive adhesive layer. The tackifying resin is not particularly limited and conventionally known materials can be used, and examples thereof include hydrocarbon tackifying resins, terpene resins, phenolic resins, rosin resins, xylene resins, epoxy resins, polyamide resins, ketone resins, and elastomer resins. Among them, rosin-based resins, hydrocarbon-based tackifying resins, terpene-based resins, and the like are preferable from the viewpoint of exhibiting thin and excellent adhesion. When the adhesive is an acrylic adhesive, a rosin-based resin is particularly preferable. In addition, when the binder is a polyester-based binder, a hydrocarbon-based tackifying resin is preferable.

Examples of the rosin-based resin include rosin resins, polymerized rosin resins, hydrogenated rosin resins, rosin ester resins, hydrogenated rosin ester resins, rosin phenol resins, and polymerized rosin esters, and specifically, unmodified rosins (raw rosins) such as gum rosins, wood rosins, and tall oil rosins, modified rosins obtained by hydrogenating, disproportionating, polymerizing, and other chemical modifications thereof, and derivatives thereof.

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

The tackifying resin may be petroleum derived or biomass derived. Among them, the biomass degree of the adhesive layer can be improved by using a biomass-derived tackifying resin. Examples of the biomass-derived tackifying resin include rosin resins and terpene resins. The biomass content of the tackifier resin is preferably 70 mass% or more, more preferably 80 mass% or more, still more preferably 90 mass% or more, and most preferably 95 to 100 mass%.

The softening point of the tackifying resin is preferably in the range of 80 to 170℃as measured by the ring and ball method, and among these, it is preferably in the range of 90 to 160℃and more preferably in the range of 100 to 150℃and even more preferably in the range of 100 to 135 ℃. By setting the softening point of the tackifier resin within the above range, the adhesiveness and cohesive force can be improved even in the film adhesive layer.

The content of the tackifier resin may be appropriately selected depending on the kind of the base polymer as the main component of the adhesive, and for example, may be in the range of 0 to 60 parts by mass, 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, based on 100 parts by mass of the base polymer as the main component of the adhesive.

(Crosslinking agent)

The adhesive may contain a crosslinking agent in order to improve the cohesive force of the adhesive layer. For example, the crosslinking agent may be 1 or 2 or more kinds of isocyanate crosslinking agents, epoxy crosslinking agents, metal chelate crosslinking agents, aziridine crosslinking agents, or the like. Among them, an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent which are reactive with a resin as a main component of the adhesive are preferable, and an isocyanate-based crosslinking agent is more preferable.

The isocyanate-based crosslinking agent is not particularly limited, as long as it has at least 2 isocyanate groups in the molecule, more preferably 3 or more. Examples of such a polyfunctional isocyanate-based crosslinking agent include: aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and the like. Specific examples of the aliphatic polyisocyanate, the alicyclic polyisocyanate, and the aromatic polyisocyanate include those exemplified by various polyisocyanates disclosed in International publication No. 2021/117826 and International publication No. 2021/153390.

Further, as the polyfunctional isocyanate compound, in addition to aliphatic polyisocyanates, alicyclic polyisocyanates and aromatic polyisocyanates, dimers and trimers based on aromatic aliphatic polyisocyanates can be used, and specifically, dimers, trimers, reaction products of trimethylolpropane and toluene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, polymers such as polymethylene polyphenyl isocyanate, polyether polyisocyanate and polyester polyisocyanate, and the like can be exemplified. Preferably, an adduct of toluene diisocyanate and trimethylolpropane can be used.

As the polyfunctional isocyanate crosslinking agent, commercially available products can also be used, specifically, as the trimer adduct of trimethylolpropane and toluene diisocyanate, trade name "BURNOCK D-40" (manufactured by DIC Co., ltd.); examples of the trimer adducts of trimethylolpropane and hexamethylene diisocyanate include the trade name "CORONATE HL" (manufactured by Japanese polyurethane Industrial Co., ltd.).

The blending amount of the crosslinking agent can be appropriately set according to the gel fraction of the adhesive layer described later.

(Additive)

The binder may contain any additive as required. Examples of the additives include viscosity modifiers (thickeners and the like), leveling agents, peeling modifiers, plasticizers, softeners, fillers such as fibers, microspheres, beads, and metal powders made of glass and plastics, conductive materials, colorants (pigments, dyes and the like), surfactants, antistatic agents, preservatives, anti-aging agents, ultraviolet absorbers, antioxidants, light stabilizers, hydrolysis inhibitors, crosslinking catalysts, retarders, silane coupling agents, surface lubricants, polymerization inhibitors, water repellents, and defoamers.

(2) Traits (3)

In order to exert an appropriate and stable adhesive force, the thickness of the adhesive layer may be 5.5 μm or more and 200 μm or less, preferably 6 μm or more and 150 μm or less, and from the viewpoint of being able to exert a higher adhesive force, it is more preferably 9 μm or more and 100 μm or less, and still more preferably 19 μm or more and 60 μm or less. In the case where the adhesive tape of the present invention is a double-sided adhesive tape, the thickness of the adhesive layer means: thickness of each adhesive layer provided on both sides of the substrate.

The gel fraction of the pressure-sensitive adhesive layer is not particularly limited, and may be in the range of 5 to 80 mass%, preferably 10 to 70 mass%, more preferably 15 to 65 mass%, even more preferably 20 to 50 mass%, and even more preferably 30 to 45 mass%, from the viewpoint of achieving both good adhesion and durability. In the case where the pressure-sensitive adhesive layer is made of an acrylic pressure-sensitive adhesive, the gel fraction of the pressure-sensitive adhesive layer is preferably in the range of 5 to 50% by mass, more preferably in the range of 10 to 40% by mass, and even more preferably in the range of 15 to 35% by mass. In the case where the pressure-sensitive adhesive layer is made of a polyester-based pressure-sensitive adhesive, the gel fraction of the pressure-sensitive adhesive layer is preferably 15 to 80 mass%, more preferably 20 to 70 mass%, even more preferably 30 to 55 mass%, and even more preferably 35 to 45 mass% of the above range.

The gel fraction is a value expressed as a percentage of the original mass of the dried insoluble component remaining after the cured adhesive layer was immersed in toluene and left for 24 hours.

Gel fraction [ mass% ] = [ (mass after toluene impregnation of adhesive layer)/(mass before toluene impregnation of adhesive layer) ]100

The adhesive layer may be transparent or may be colored. In the case of being used for optical applications, the total light transmittance of the pressure-sensitive adhesive layer in visible light is preferably 90% or more, more preferably 92% or more, and even more preferably 92.5% or more. The haze of the pressure-sensitive adhesive layer in visible light is preferably 2% or less, more preferably 1% or less, and still more preferably 0.8% or less. This is because the occurrence of defects in the pressure-sensitive adhesive layer due to impurities contained in the base material and the release liner is suppressed by providing the pressure-sensitive adhesive layer with the total light transmittance and haze.

The pressure-sensitive adhesive layer can be formed by a known common method, for example, by applying the pressure-sensitive adhesive composition containing the pressure-sensitive adhesive and optionally a solvent to one surface of a substrate or a release treated surface of a release liner, drying the composition, and optionally curing the composition. As a method for applying the adhesive composition, for example, a gravure roll coater, a reverse roll coater, a roll lick coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, or the like can be used.

The drying condition of the coating film of the adhesive composition is not particularly limited, and the drying temperature is preferably 60 to 140 ℃, and among them, 80 to 120 ℃. The drying time is preferably 0.5 to 30 minutes, and more preferably 1 to 5 minutes. The conditions for the aging treatment can be appropriately set, and are preferably room temperature (23 ℃) for 1 to 30 days at 70 ℃, particularly preferably 1 to 20 days at 23 ℃, more preferably 3 to 14 days at 23 ℃, and still more preferably 1 to 10 days at 40 ℃.

4. Adhesive tape

The adhesive tape of the present invention may be a single-sided adhesive tape having an adhesive layer and a release liner provided on one side of a substrate. The pressure-sensitive adhesive tape of the present invention may be a double-sided pressure-sensitive adhesive tape in which the pressure-sensitive adhesive layers are provided on both sides of the substrate, and release liners are provided on the surfaces of the pressure-sensitive adhesive layers provided on one side of the substrate or on each surface of the pressure-sensitive adhesive layers provided on both sides of the substrate.

In the case where the pressure-sensitive adhesive tape of the present invention is a single-sided pressure-sensitive adhesive tape, the substrate may have any layer on the surface opposite to the surface on which the pressure-sensitive adhesive layer is provided. Examples of the optional layer include a coloring layer, a conductive layer, an antistatic layer, a flame retardant layer, a heat resistant layer, and an insulating layer.

The adhesive tape of the present invention may be transparent or opaque. In the case of use in optical applications, the release liner-removed pressure-sensitive adhesive tape preferably has a total light transmittance of 90% or more, more preferably 92% or more, and still more preferably 92.5% or more in visible light. The haze of the release liner-removed pressure-sensitive adhesive tape in visible light is preferably 2% or less, more preferably 1% or less, and still more preferably 0.8% or less. This is because, by providing the adhesive tape with the total light transmittance and haze, the impurities contained in the base material are reduced, and the occurrence of defects in the adhesive layer due to the impurities contained in the base material and the release liner is suppressed.

The adhesive tape of the present invention may be colored. When the adhesive tape of the present invention is colored, the adhesive layer and/or the substrate may contain a colorant such as a pigment or dye.

5. Method of manufacture

The method for producing the pressure-sensitive adhesive tape of the present invention is not particularly limited, and a known method can be used. Among them, the following first or second embodiment manufacturing method can be preferably used. Details of the release liner, the base material, and the adhesive layer used or formed in each step, and the forming method are as described above.

(First mode)

A first aspect of the method for producing an adhesive tape according to the present invention is a method for producing an adhesive tape comprising at least the steps of: an adhesive layer forming step of forming an adhesive layer by applying an adhesive to at least one surface of a base material containing a recycled resin; and a bonding step of bonding a release liner containing a recycled resin to the surface of the adhesive layer on at least one surface side of the base material. In the bonding step, the release liner preferably bonds the release treated surface to the pressure-sensitive adhesive layer.

In the first aspect of the production method, the substrate preferably has the following structure [ 1a ] or [ 2a ].

A layer single-layer structure in which the content of the regenerated resin is 50 mass% or more and 100 mass% or less and the content of the mechanically regenerated resin is 95 mass% or less;

[ 2a ] a multilayer structure as follows: at least one of the outermost layers is a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less, or a layer having a content of a virgin resin of 50 mass% or more.

When the substrate has the structure of [ 1a ] or [ 2a ], it is preferable that an adhesive layer is formed by applying an adhesive to at least one surface of the substrate having a single-layer structure or at least one surface of the outermost layer of the substrate having a multi-layer structure in the adhesive layer forming step. In the above-described adhesive layer forming step, when the adhesive layer is formed on the surface of the base material, occurrence of defects in the adhesive layer due to impurities contained in the base material can be suppressed.

In the pressure-sensitive adhesive layer forming step, a pressure-sensitive adhesive may be applied to both surfaces of the substrate having a single layer structure or to both outermost layers of the substrate having a multilayer structure, respectively, and the pressure-sensitive adhesive layer may be formed on both surfaces of the substrate. In this case, the substrate having a multilayer structure is preferably: the outermost layers of the two are layers each having a regenerated resin content of 50 mass% or more and 100 mass% or less and a mechanically regenerated resin content of 95 mass% or less, or a layer having a virgin resin content of 50 mass% or more. In the above-described adhesive layer forming step, the adhesive can be applied to both sides of the substrate to form the adhesive layer, and in each of the adhesive layers formed on both sides of the substrate, occurrence of defects due to impurities contained in the substrate can be suppressed.

In the first aspect of the present invention, the release liner preferably has the following structure [ 1b ] or [ 2b ].

[ 2b ] a multilayer structure as follows: at least one of the outermost layers is a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less, or a layer having a content of a virgin resin of 50 mass% or more.

When the release liner has the structure of [ 1b ] or [ 2b ], in the bonding step, it is preferable that the surface of the adhesive layer on at least one surface side of the base material is bonded to one surface of the release liner having a single-layer structure or to the surface of the outermost layer of the release liner having a multi-layer structure. In the case where the adhesive tape obtained by the method of the first aspect is a double-sided adhesive tape, in the attaching step, it is preferable that one surface of the single-layer structure of the release liner or the surface of the outermost layer of the multi-layer structure is attached to one or both surfaces of the adhesive layer provided on both sides of the substrate. In the above bonding step, when the release liner is bonded to the surface of the pressure-sensitive adhesive layer, defects in the pressure-sensitive adhesive layer due to impurities contained in the release liner can be prevented, and the pressure-sensitive adhesive tape having reduced adhesiveness and suppressed appearance defects due to uneven adhesive force can be produced.

When the adhesive tape obtained by the method of the first aspect is a double-sided adhesive tape, and the release liner is bonded to the surface of the adhesive layer on one surface side of the substrate in the bonding step, the release liner having a multilayer structure is preferably: the two outermost layers are each a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less, or a layer having a content of a virgin resin of 50 mass% or more. When a double-sided adhesive tape having a release liner provided on one side thereof is formed into a roll, occurrence of defects can be prevented even if the exposed surface of the adhesive layer is in contact with the release liner.

(Second mode)

A second aspect of the method for producing an adhesive tape according to the present invention is a method for producing an adhesive tape comprising the steps of: an adhesive layer forming step of forming an adhesive layer by applying an adhesive to a release liner containing a recycled resin, thereby obtaining a release liner with an adhesive layer; and a bonding step of bonding a surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive-layer-equipped release liner to at least one surface of a base material containing a recycled resin. In the pressure-sensitive adhesive layer forming step, the pressure-sensitive adhesive layer is formed on the release-treated surface of the release liner.

In the second aspect of the present invention, the release liner preferably has the structure [ 1b ] or [ 2b ] described in the first aspect of the present invention. In this case, in the adhesive layer forming step, it is preferable that an adhesive is applied to one surface of the release liner having a single layer structure or to the surface of the outermost layer of the release liner having a multilayer structure to form an adhesive layer. This is because, in the pressure-sensitive adhesive layer forming step, when the pressure-sensitive adhesive layer is formed on the surface of the release liner, occurrence of defects in the pressure-sensitive adhesive layer due to impurities contained in the release liner can be suppressed.

In the second aspect of the present invention, the substrate preferably has the structure [ 1a ] or [ 2a ] described in the first aspect of the present invention. When the substrate has the structure of [ 1a ] or [ 2a ], the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer-containing release liner is preferably bonded to at least one surface of the single-layer substrate or to the outermost layer of the multi-layer substrate in the bonding step. This is because, when the base material is bonded to the surface of the pressure-sensitive adhesive layer in the bonding step, defects in the pressure-sensitive adhesive layer due to impurities contained in the base material can be prevented, and the pressure-sensitive adhesive tape can be produced with reduced tackiness due to uneven adhesion and suppressed appearance defects.

In the bonding step, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer-attached release liner may be bonded to both surfaces of the single-layer substrate or to both outermost layers of the multi-layer substrate. In this case, the substrate of the multilayer structure is preferably: the two outermost layers are each a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less, or a layer having a content of a virgin resin of 50 mass% or more. In the above bonding step, the release liners having the adhesive layers can be bonded to both sides of the base material, respectively, to form the adhesive layers, and occurrence of defects due to impurities contained in the base material can be suppressed in the adhesive layers provided on both sides of the base material.

The composition and properties of the release liner, the composition and properties of the substrate, the composition and properties of the adhesive layer, and the method of forming each layer in each step of the production methods according to the first and second aspects are as described in the items "1. Substrate", "2. Release liner", and "3. Adhesive layer" above.

6. Use of the same

The use of the pressure-sensitive adhesive tape of the present invention is not particularly limited, but since the pressure-sensitive adhesive tape is thick and the rate of the regenerated raw material of the whole pressure-sensitive adhesive tape is high, the pressure-sensitive adhesive tape can be used particularly effectively in portable electronic devices and the like in which the use of the regenerated material is advancing. As a specific usage, the present invention is applicable to, for example, insulation, protection, fixation, and the like of various components in portable electronic devices such as electronic notebooks, mobile phones, smart phones, tablet terminals, PHS, cameras, and music players. Among them, the pressure-sensitive adhesive tape of the present invention having a specific substrate and release liner is useful as an optical pressure-sensitive adhesive tape for optical parts and the like because it is thick, has excellent adhesive force and good appearance in addition to a high recycling rate.

Examples (example)

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

1. Production of granules

< Regeneration particle A >)

The release film obtained by coating the silicone on the polyester film was cut into 1cm×1cm pieces and chipped. About 10kg of the chips were put into a treatment vessel, and 2.0g of a caustic soda aqueous solution having a concentration of 0.7 mass% and polyethylene glycol ether (manufactured by Emulgen106 Kagaku Co., ltd.) as a higher alcohol were put together, followed by stirring at 105℃for 15 minutes at a rotation speed of about 100 rpm. After stirring, the treatment liquid was discharged, and the liquid was removed sufficiently, followed by washing with water for 10 minutes.

Then, 10.0g of a caustic soda aqueous solution having a concentration of 1% by mass and polyethylene glycol ether as a higher alcohol were put into the chip sample after the first caustic alkali treatment, and the mixture was stirred at 120℃for 40 minutes at a rotation speed of about 200 rpm. After stirring, the treatment liquid was discharged, and the liquid was removed sufficiently, and then, the mixture was washed with sufficient running water for 15 minutes to remove foreign matters.

Then, the drained washed chips were taken out and dried at 100℃for 60 minutes. The dried chips were further vacuum-dried, and then heated and melted to 280℃to form a polyester film, which was cut to obtain mechanically regenerated polyester particles (regenerated particles A). The regeneration raw material rate of the regenerated particles A was 100%.

< Regeneration particle B >)

A stirring device equipped with two sections of 45 ° paddle blades was provided in the depolymerization tank. The upper 45 ° blade is set at a depth of 20mm from the position of the liquid surface as the depolymerization liquid. The lower 45 ° blade is set at a position 500mm from the position as the liquid surface. A release film obtained by coating a silicone on a polyester film was cut to 20mm square, 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 put into the depolymerization tank. Then, the stirring device of the depolymerization tank was stirred at 50rpm, and the temperature was raised to 190℃and kept for 1 hour, so that a part of polyethylene terephthalate was depolymerized, and it was confirmed that the film-shaped release agent was suspended. Then, after 0.04 parts by mass of ethyl acid phosphate was added to the reaction mixture, 0.5 parts by mass of spherical organic crosslinked particles having an average particle diameter of 1.1 μm and 0.03 parts by mass of antimony trioxide were added, and the reaction mixture was kept at 190℃and after 4 hours, the depolymerization reaction was completed. The resulting polymer was cut to obtain chemically regenerated polyester particles (regenerated particles B). The regeneration raw material rate of the regenerated particles B was 99.4%.

< Regeneration particle C >)

The flakes obtained by pulverizing the PET bottle were melt-extruded by an extruder and cut to obtain mechanically regenerated polyester particles (regenerated particles C). The regeneration raw material rate of the regenerated particles C was 100%.

< Regeneration particle D >)

The regenerated particles C obtained above were exposed to a nitrogen gas stream containing ethylene glycol vapor in an amount of 0.086 g/(hr·particle kg) (=86 ppm) per unit time of 1kg of the relative particles in a rotary dryer, and the recovered particles were brought into contact with ethylene glycol for 6 hours. The treatment temperature was carried out at 220 ℃. Further, after 0.04 parts by mass of ethyl acid phosphate was added to the reaction mixture, 0.5 parts by mass of spherical organic crosslinked particles having an average particle diameter of 1.1 μm and 0.03 parts by mass of antimony trioxide were added, polycondensation was carried out for 4 hours, solid-phase polymerization was carried out at 230℃for 20 hours at 0.5mmHg, and the obtained polymer was cut to obtain chemically regenerated polyester particles (regenerated particles D). The regeneration feed rate of the regenerated particles D was 99.4%.

< Primary particles E >)

100 Parts by mass of dimethyl terephthalate and 60 parts by mass of ethylene glycol were used as starting materials, 0.09 parts by mass of magnesium acetate tetrahydrate was fed to a reactor as a catalyst, the reaction initiation temperature was 150 ℃, methanol was distilled off and the reaction temperature was gradually raised, and after 3 hours, it was set to 230 ℃. After 4 hours, the transesterification reaction was substantially ended. After 0.04 parts by mass of ethyl acid phosphate was added to the reaction mixture, 0.5 parts by mass of spherical organic crosslinked particles having an average particle diameter of 1.1 μm and 0.03 parts by mass of antimony trioxide were added to carry out polycondensation reaction for 4 hours. On the other hand, the pressure gradually decreased from the normal pressure to 0.3mmHg. After the start of the reaction, the reaction was stopped at a point corresponding to an intrinsic viscosity of 0.65 by a change in stirring power of the reaction vessel, and the polymer was discharged under nitrogen pressure to obtain virgin polyester particles (virgin particles E). The regeneration raw material rate of the primary particles E was 0%.

2. Production of polyester film

< Polyester film 1 >)

The unstretched sheet was obtained by using a vented twin-screw extruder capable of three-layer extrusion of layer 1/layer 2/layer 3 (cooling roll layer side), using regenerated particles B as the material of layer 1, regenerated particles a as the material of layer 2, regenerated particles B as the material of layer 3, melt-extruding at 295 ℃, and cooling and solidifying on a cooling roll having a surface temperature of 38 ℃ by using an electrostatic application method. Next, after stretching 1.8 times in the machine direction at 82 ℃, introducing into a tenter, stretching 2.0 times in the transverse direction at 110 ℃, and further performing heat treatment at 225℃to obtain a polyester film 1 (recycled material ratio: 99.8%) having a thickness of 25 μm and having a three-layer structure of layer 1 (thickness 5 μm)/layer 2 (thickness 15 μm)/layer 3 (thickness 5 μm).

< Polyester film 2 >)

An unstretched sheet was obtained by using a vented twin-screw extruder capable of three-layer extrusion of layer 1/layer 2/layer 3 (chill roll layer side), using regenerated particles D as the material of layer 1, regenerated particles C as the material of layer 2, regenerated particles D as the material of layer 3, melt-extruding at 295 ℃, and cooling and solidifying on a chill roll having a surface temperature of 38 ℃ using an electrostatic charge application method. Next, after stretching 1.8 times in the machine direction at 82 ℃, the film was introduced into a tenter, stretching 2.0 times in the transverse direction at 110℃and further heat treatment was performed at 225℃to obtain a polyester film 2 (recycled material ratio: 99.8%) having a thickness of 25 μm and having a three-layer structure of layer 1 (thickness 5 μm)/layer 2 (thickness 15 μm)/layer 3 (thickness 5 μm).

< Polyester film 3 >)

The unstretched sheet was obtained by using a vented twin-screw extruder capable of three-layer extrusion of layer 1/layer 2/layer 3 (cooling roll layer side), using primary particles E as the material of layer 1, using regenerated particles C as the material of layer 2, using primary particles E as the material of layer 3, melt-extruding at 295 ℃, and cooling and solidifying on a cooling roll having a surface temperature set at 38 ℃ using an electrostatic application method. Next, after stretching 1.8 times in the longitudinal direction at 82 ℃, the film was introduced into a tenter, stretching 2.0 times in the transverse direction at 110℃and further heat treatment was performed at 225℃to obtain a polyester film 3 (recycled material ratio: 84.0%) having a thickness of 25 μm and having a three-layer structure of layer 1 (thickness 2 μm)/layer 2 (thickness 21 μm)/layer 3 (thickness 2 μm).

< Polyester film 4 >)

An unstretched sheet was obtained by using a vented twin-screw extruder capable of three-layer extrusion of layer 1/layer 2/layer 3 (chill roll layer side), using regenerated particles D as the material of layer 1, regenerated particles C as the material of layer 2, regenerated particles D as the material of layer 3, melt-extruding at 295 ℃, and cooling and solidifying on a chill roll having a surface temperature of 38 ℃ using an electrostatic charge application method. Next, after stretching 1.8 times in the longitudinal direction at 82 ℃, the film was introduced into a tenter, stretching 2.0 times in the transverse direction at 110℃and further heat treatment was performed at 225℃to obtain a 12 μm thick polyester film 4 having a three-layer structure of layer 1 (thickness 2 μm)/layer 2 (thickness 8 μm)/layer 3 (thickness 2 μm) (recycling yield: 99.8%).

< Polyester film 5 >)

The primary particles E were melt-extruded at 295℃by a twin-screw extruder with a vent, and cooled and solidified on a cooling roll set to a surface temperature of 38℃by an electrostatic encryption method to obtain an unstretched sheet. Next, after stretching 1.8 times in the machine direction at 82℃and stretching 2.0 times in the transverse direction at 110℃the resultant film was further heat-treated at 225℃to give a single-layer polyester film 5 (recycled material ratio: 0.0%) having a thickness of 25. Mu.m.

< Polyester film 6 >)

The regenerated particles C were melt-extruded at 295℃by a twin-screw extruder with a vent, and cooled and solidified on a cooling roll set to a surface temperature of 38℃by an electrostatic encryption method to obtain an unstretched sheet. Next, after stretching 1.8 times in the machine direction at 82℃and stretching 2.0 times in the transverse direction at 110℃the resultant film was further heat-treated at 225℃to give a single-layer polyester film 6 (recycled material ratio: 100.0%) having a thickness of 25. Mu.m.

The outline of the polyester films 1 to 6 is shown in the following table.

TABLE 1

3. Production of release liners

< Release liner 1 >)

One side of the polyester film 1 was subjected to corona treatment, and an addition reaction type silicone release agent a was applied to the corona treated side by a micro gravure coater so that the thickness after drying became 0.1 μm, heated in a hot air circulation dryer at 110 ℃ for 1 minute, and cured at 40 ℃ for 2 days to obtain a release liner 1 (regeneration raw material ratio 99.4% and biomass content 0.0%). The addition reaction type silicone release agent a was a mixture obtained by mixing 10 parts by mass of SRX-211 manufactured by DowCorningToray corporation with 0.1 part by mass of a platinum catalyst SRX212 and 90 parts by mass of a 50/50 mixed solvent of toluene and ethyl acetate.

< Release liners 2-4 >)

Release liners 2 to 4 are obtained in the same manner as release liner 1, except that the polyester film 3, the polyester film 5, or the polyester film 6 is used instead of the polyester film 1. The regeneration raw material ratios and biomass degrees of the release liners 2 to 4 are shown in the following table 2.

4. Preparation of the adhesive

Preparation of polyester adhesive alpha

Into a reaction tank equipped with a thermometer, a stirrer, a rectifying column, a nitrogen inlet pipe, and a vacuum apparatus, 0.14 equivalents of isophthalic acid, 0.5 equivalents of sebacic acid, 0.5 equivalents of azelaic acid, 1.4 equivalents of ethylene glycol, 0.05 equivalents of diethylene glycol, and 0.0064 mass% of germanium dioxide as a catalyst were charged, and the temperature was slowly raised to an internal temperature of 250℃to conduct esterification reaction for 4 hours. Then, the temperature was raised to 270℃and the pressure was reduced to 1.33hPa, and the polycondensation reaction was carried out for 3 hours to produce a polyester resin (A-1). The weight average molecular weight of the obtained polyester resin (A-1) was 90000 and the biomass fraction was 92%. Among materials for preparing polyester-based resins, materials derived from biomass are used for sebacic acid, azelaic acid, ethylene glycol and diethylene glycol.

Next, 10 parts by mass of "Haritac PCJ" (biomass: 95% by mass) of "Ha Lima Kagaku Co., ltd.) as a thickener (toluene diisocyanate and trimethylolpropane adduct (produced by DIC Co., ltd." BURNOCK D-40", hereinafter abbreviated to" D-40 ") as a crosslinking agent (1.3 parts by mass) was blended into 100 parts by mass of the polyester resin (A-1) to obtain a polyester adhesive α having a gel fraction of 17% by mass, a biomass of 91.2% and a recycled material fraction of 0.0%.

Preparation of acrylic Adhesives beta

97.98 Parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid, 0.02 part by mass of 4-hydroxybutyl acrylate, and 0.2 part by mass of azobisisobutyronitrile as a polymerization initiator were subjected to solution polymerization in an ethyl acetate solution at 80℃for 8 hours to obtain an acrylic polymer having a weight average molecular weight of 90 tens of thousands. To 100 parts by mass of the acrylic polymer based on the amount of the solid content, 50 parts by mass of polymerized rosin ester (trade name "D-135" manufactured by Kagaku chemical Co., ltd.) based on the amount of the solid content was added, and ethyl acetate was added to prepare a binder solution having a solid content of 40% by mass. To the above adhesive solution, 1 part by mass of an isocyanate-based crosslinking agent (trade name "NC40" DIC corporation) in terms of the amount of solid components was further added, and the mixture was stirred and mixed to prepare an acrylic adhesive β. The polymerized rosin ester is a biomass raw material. The biomass content of the acrylic binder β was 32.8%, the regeneration raw material rate was 0.0%, and the regeneration and biomass raw material rate was 32.8%.

5. Production of adhesive tape

Example 1

The release liner 1 was coated with a polyester adhesive α on the release agent-coated surface thereof with a comma coater so that the thickness thereof after drying was 50 μm, and the coated surface was dried at 100℃for 2 minutes to form an adhesive layer, thereby obtaining a release liner with an adhesive layer. 2 release liners with adhesive layers were prepared. The adhesive tape of example 1 having a laminate structure of release liner/adhesive layer/substrate/adhesive layer/release liner was produced by using the polyester film 1 as a base material, and curing the surface of the adhesive layer of the release liner with the adhesive layer on each side of the polyester film 1 at 40℃for 1 week.

(Examples 2 to 4)

Adhesive tapes of examples 2 to 4 were produced in the same manner as in example 1, except that the polyester films 2 to 4 were used as the base material instead of the polyester film 1.

Example 5

An adhesive tape of example 5 was produced in the same manner as in example 1, except that the release liner 2 was used instead of the release liner 1.

Example 6

The release liner 1 was coated with a polyester adhesive α on the release agent-coated surface with a comma coater so that the thickness after drying became 50 μm, and dried at 100 ℃ for 2 minutes to form an adhesive layer, thereby obtaining a release liner with an adhesive layer. The pressure-sensitive adhesive layer of the release liner having a pressure-sensitive adhesive layer was applied to one side of the polyester film 1, and cured at 40℃for 1 week to prepare an adhesive tape of example 6 having a laminate structure of a substrate, a pressure-sensitive adhesive layer and a release liner.

Example 7

An adhesive tape of example 7 was produced in the same manner as in example 1, except that the acrylic adhesive β was used instead of the polyester adhesive α.

Example 8

An adhesive tape of example 8 was produced in the same manner as in example 1, except that the acrylic adhesive β was used in place of the polyester adhesive α and the release liner 3 was used in place of the release liner 1.

Example 9

An adhesive tape of example 9 was produced in the same manner as in example 1, except that the acrylic adhesive β was used in place of the polyester adhesive α and the release liner 4 was used in place of the release liner 1.

Example 10

The polyester film 6 was coated with an acrylic adhesive β by a comma coater so that the thickness after drying became 50 μm, and dried at 100 ℃ for 2 minutes to form an adhesive layer 1, thereby obtaining a substrate with an adhesive layer. The release agent-coated surface of the release liner 1 was bonded to the surface of the pressure-sensitive adhesive layer 1 of the pressure-sensitive adhesive layer-attached substrate, to obtain a single-sided tape. On the base material surface (surface of the polyester film 6) of the single-sided tape, an acrylic adhesive β was applied by a comma coater so that the thickness after drying became 50 μm, and dried at 100 ℃ for 2 minutes to form an adhesive layer 2. The release agent coated surface of the release liner 1 was bonded to the surface of the adhesive layer 2 to form a double-sided tape, and the tape was cured at 40 ℃ for 1 week to form an adhesive tape of example 10 having a laminate structure of release liner/adhesive layer 1/substrate/adhesive layer 2/release liner.

The structures of the adhesive tapes obtained in examples 1 to 10 are shown in the following table.

TABLE 2

6. Evaluation

The pressure-sensitive adhesive tapes obtained in examples 1 to 10 were evaluated by the following evaluation methods.

< Regeneration raw Material Rate >)

Using the calculation formula described above, the regeneration raw material rate of each layer constituting the pressure-sensitive adhesive tape was calculated. The regeneration material ratio of the entire adhesive tape was calculated and evaluated according to the following criteria. The results are shown in tables 1 to 3.

(Evaluation criterion)

And (3) the following materials: the adhesive tape has a regeneration raw material rate of 50% or more (excellent environmental protection performance)

And (2) the following steps: the adhesive tape has a regeneration raw material rate of 40 to less than 50 percent (practically sufficient environmental protection performance)

X: the regeneration raw material rate of the adhesive tape is less than 40 percent (the adhesive tape does not have sufficient environmental protection performance)

< Biomass degree >)

Using the calculation formula described above, the biomass level of each layer constituting the pressure-sensitive adhesive tape and the whole pressure-sensitive adhesive tape was calculated. The results are shown in tables 1 to 3.

< Regeneration and Biomass raw Material Rate >)

Using the calculation formula described above, the proportions of the regenerated material and the biomass material (regenerated and biomass material ratios) of the pressure-sensitive adhesive tape were calculated and evaluated according to the following criteria. The results are shown in Table 3.

(Evaluation criterion)

And (3) the following materials: the regeneration and biomass raw material rate of the adhesive tape is more than 90 percent (with excellent environmental protection performance)

And (2) the following steps: the regeneration rate of the adhesive tape is 60% or more and less than 90% (practically, the adhesive tape has sufficient environmental protection performance)

X: the regeneration rate of the adhesive tape and the biomass raw material rate are less than 60 percent (the adhesive tape has insufficient environmental protection performance)

< Easiness of regeneration of adhesive tape >

The regeneration suitability (regeneration easiness) of the adhesive tape was judged by the following criteria. The results are shown in Table 3.

(Reference)

And (3) the following materials: the polyester material of the pressure-sensitive adhesive tape has a proportion of 90% or more (excellent regeneration suitability)

And (2) the following steps: the polyester material of the pressure-sensitive adhesive tape has a proportion of 70% or more and less than 90% (practically sufficient regeneration adaptability)

X: the proportion of the polyester-based material of the adhesive tape is less than 70% (not having sufficient regeneration suitability)

Adhesive coating adaptability (appearance)

The release liner of the adhesive tape was released, and the number of foaming of 1mm ² or more in 1000m ² (a 1m×1000m quadrangle) of the adhesive layer was visually confirmed from the side of the adhesive layer, and evaluated according to the following criteria. The results are shown in Table 3.

(Evaluation criterion)

And (3) the following materials: foaming of 0 (excellent coating adaptability)

And (2) the following steps: foaming is 1 to 10 (practically sufficient coating adaptability)

X: foaming is more than 11 (insufficient coating adaptability)

< Adhesion >

The adhesive tape was cut to 20mm in width, and 180℃peel adhesion (peel angle: 180℃stretching speed: 300 mm/min, 23℃X 50% RH, adherend: stainless steel plate, adhesion time: 1 hour) was measured using a Tensilon tensile tester according to JIS Z0237. When the sample to be evaluated was a double-sided tape, the single-sided surface was laminated with a 25 μm polyethylene terephthalate film and measured. The results are shown in Table 3.

< Holding force >

The adhesive tape was cut to a width of 20mm, and a load of 100g (20 mm. Times.20 mm) was applied in the vertical direction in accordance with JIS Z0237, and the dropping time (hours) was measured in an atmosphere at 100 ℃. When the sample to be evaluated was a double-sided tape, the single-sided surface was laminated with a 25 μm polyethylene terephthalate film and measured. The results are shown in Table 3.

In table 3, "adhesive tape" is merely indicated as "adhesive tape".

TABLE 3

The adhesive tapes of examples 1 to 7 and examples 9 to 10 (examples) had a total thickness of the adhesive tapes other than the release liner exceeding 20 μm, a regeneration raw material ratio of 30 mass% or more, and a thick, high regeneration raw material ratio. On the other hand, the adhesive tape of example 8 (comparative example) had a regeneration raw material ratio of 14.2 mass% for the entire adhesive tape, and was poor in environmental friendliness.

In examples 1 to 7 and examples 9 to 10, the adhesive tapes of examples 1 to 7 were evaluated as "very good" in terms of the adhesive coating suitability, whereas the adhesive tapes of examples 9 to 10 were evaluated as poor in terms of the adhesive coating suitability in terms of 1 to 7, and a large amount of bubbles were generated in the adhesive layer, resulting in poor appearance. The adhesive tapes of examples 9 to 10 were inferior in adhesion to the adhesive tape of example 7 using the same adhesive β. These differences are that, by particularly defining the configuration of the base material and the release liner in contact with the adhesive layer in the adhesive tapes of examples 1 to 7, occurrence of defects in the adhesive layer can be suppressed.

Symbol description

1 … Substrate, 2, 4 … adhesive layer, 3, 5 … release liner, 10 … adhesive tape.

Claims

1. An adhesive tape, characterized in that:

the adhesive tape comprises a substrate, an adhesive layer provided on one or both sides of the substrate, and a release liner provided on the surface of the adhesive layer on at least one side of the substrate,

At least the substrate and the release liner each contain a recycled resin,

The total thickness of the adhesive tape excluding the release liner is greater than 20 μm,

The proportion of the regeneration raw material in the adhesive tape is more than 30 mass%.

2. The adhesive tape according to claim 1, wherein,

The substrate has:

A single-layer structure in which the content of the regenerated resin is 50 mass% or more and 100 mass% or less and the content of the mechanically regenerated resin is 95 mass% or less, or

The following multilayer structure: at least the outermost layer on the pressure-sensitive adhesive layer side is a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less, or a layer having a content of a virgin resin of 50 mass% or more.

3. The adhesive tape according to claim 1 or 2, wherein,

The base material has a three-layer structure having a layer A1, a layer A2 and a layer A3 in this order from the adhesive layer side,

The layer A1 and the layer A3 are each a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less; or a layer having a virgin resin content of 50 mass% or more,

The layer A2 is a layer having a mechanically regenerated resin content of 50 mass% or more and 100 mass% or less.

4. The adhesive tape according to claim 1 or 2, wherein,

The content of the regenerated resin in the base material is 90 mass% or more.

5. The adhesive tape according to claim 1 or 2, wherein,

The recycled resin contained in the base material is recycled polyester resin.

6. The adhesive tape according to claim 1 or 2, wherein,

The release liner has:

7. The adhesive tape according to claim 1 or 2, wherein,

The release liner has a three-layer structure having a layer B1, a layer B2 and a layer B3 in this order from the adhesive layer side,

The layer B1 and the layer B3 are each a layer having a content of a regenerated resin of 50 mass% or more and 100 mass% or less and a content of a mechanically regenerated resin of 95 mass% or less; or a layer having a virgin resin content of 50 mass% or more,

The layer B2 is a layer having a mechanically regenerated resin content of 50 mass% or more and 100 mass% or less.

8. The adhesive tape according to claim 1 or 2, wherein,

The content of the regenerated resin in the release liner is 90 mass% or more.

9. The adhesive tape according to claim 1 or 2, wherein,

The regenerated resin contained in the release liner is regenerated polyester resin.

10. The adhesive tape according to claim 1 or 2, wherein,

The thickness of the adhesive layer is 9 [ mu ] m or more and 100 [ mu ] m or less.

11. The adhesive tape according to claim 1 or 2, wherein,

The adhesive tape further comprises a biomass material, and the ratio of the regenerated raw material to the biomass raw material of the adhesive tape is 60 mass% or more.

12. The method for producing an adhesive tape according to any one of claims 1 to 11, comprising at least the steps of:

An adhesive layer forming step of forming an adhesive layer by applying an adhesive to at least one surface of a base material containing a recycled resin; and

And a bonding step in which a release liner containing a recycled resin is bonded to the surface of the adhesive layer on at least one surface side of the base material.

13. The method for manufacturing an adhesive tape according to claim 12, wherein,

The substrate and the release liner each independently have:

The following multilayer structure: at least one of the outermost layers is a layer having a regenerated resin content of 50 mass% or more and 100 mass% or less and a mechanically regenerated resin content of 95 mass% or less, or a layer having a virgin resin content of 50 mass% or more,

In the adhesive layer forming step, an adhesive is applied to at least one surface of the single-layer substrate or at least the surface of the outermost layer of the multi-layer substrate to form an adhesive layer,

14. The method for producing an adhesive tape according to any one of claims 1 to 11, comprising at least the steps of:

An adhesive layer forming step of forming an adhesive layer by applying an adhesive to a release liner containing a recycled resin, thereby obtaining a release liner with an adhesive layer; and

And a bonding step of bonding the surface of the pressure-sensitive adhesive layer-attached release liner to at least one surface of a base material containing a recycled resin.

15. The method for manufacturing an adhesive tape according to claim 14, wherein,

The substrate and the release liner each independently have: