KR20240133953A - Carrier sheet for flexible device - Google Patents

Abstract

The present invention aims to provide a carrier sheet that has excellent antistatic properties and can suppress haze values in each process.
As a means for solving such a problem, a carrier sheet for a flexible device for protecting and transporting a flexible device is provided, comprising: a substrate; an adhesive layer laminated on one surface side of the substrate; and a release sheet laminated on a surface of the adhesive layer opposite to the substrate, wherein all of the substrate, the adhesive layer and the release sheet have antistatic properties, and the adhesive layer contains, as an antistatic agent, a pyridinium hexafluorophosphate-based compound and a fluorosulfonylimide-based compound.

Description

{CARRIER SHEET FOR FLEXIBLE DEVICE}

The present invention relates to a carrier sheet used for protecting and returning a flexible device.

In the case of devices such as optical or electronic components, a carrier sheet composed of a substrate and an adhesive layer is sometimes attached to the surface of the device in order to protect the surface of the device while returning it during processes such as processing, assembly, and inspection. This carrier sheet is peeled off from the device when the need for protection or return of the device is no longer necessary.

As for the devices that are the transported objects, there have been many rigid ones in the past, but recently, flexible devices have appeared. For example, recently, as an optical member, there has been an active movement to move from rigid liquid crystal devices to flexible organic light emitting diode (OLED) devices. Accordingly, carrier sheets that support such flexible devices are also required.

However, in the carrier sheet as described above, when the peeling sheet is peeled from the adhesive layer during use and also peeled from the device after use, static electricity may be generated due to peeling charging at that time. In addition, the device to which the carrier sheet is attached may be frictionally charged during transportation or during the manufacturing process.

When static electricity occurs, dust or dirt in the air adheres to the device, which leads to device failure. Therefore, it is required to provide antistatic properties to the carrier sheet to prevent static electricity from occurring.

Here, Patent Document 1 discloses a silicone adhesive composition for returning a flexible substrate containing a silicone adhesive and an antistatic agent.

Japanese Patent No. 5406707

The invention according to Patent Document 1 takes antistatic properties into consideration for flexible devices, but it is difficult to obtain sufficient antistatic properties in each process. In addition, when the amount of antistatic agent added is increased in order to obtain sufficient antistatic properties, the adhesive layer becomes cloudy and the haze value increases, making it unusable for inspection processes of optical systems.

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a carrier sheet which has excellent antistatic properties in each process and can suppress the haze value to a low level.

In order to achieve the above object, firstly, the present invention provides a carrier sheet for a flexible device for protecting and transporting a flexible device, comprising: a substrate; an adhesive layer laminated on one surface side of the substrate; and a release sheet laminated on a surface of the adhesive layer opposite to the substrate; wherein all of the substrate, the adhesive layer, and the release sheet have antistatic properties (Invention 1).

The carrier sheet according to the invention (invention 1) has excellent antistatic properties in each process since the substrate, the adhesive layer, and the release sheet all have antistatic properties. For example, when the release sheet is peeled from the adhesive layer, or when the carrier sheet is peeled from the flexible device, or during processes such as processing, lamination, and inspection of the flexible device, or during transport, or when the carrier sheet is fed out, static electricity is unlikely to be generated, so that dust or dirt in the air can be suppressed from adhering to the flexible device due to static electricity. In addition, since the substrate, the adhesive layer, and the release sheet each have antistatic properties, the amount of antistatic agent used in the adhesive layer can be reduced compared to, for example, a case where the antistatic properties of the entire adhesive layer are satisfied by a single layer. As a result, the haze value of the adhesive layer, and further, the haze value of the entire carrier sheet, can be suppressed low.

In the above invention (invention 1), it is preferable that the substrate has a substrate film and an antistatic layer formed on one surface side of the substrate film, and that the pressure-sensitive adhesive layer is laminated on the substrate so as to be positioned on the other surface side of the substrate film (invention 2). Furthermore, it is also preferable that the pressure-sensitive adhesive layer is laminated on the substrate so as to be in contact with the other surface of the substrate film.

In the above inventions (inventions 1 and 2), it is preferable that the adhesive layer contains an antistatic agent (invention 3).

In the above inventions (inventions 1 to 3), it is preferable that the peeling sheet has a support and an antistatic layer formed on at least one surface side of the support (invention 4).

In the above inventions (inventions 1 to 4), when a voltage of 100 V is applied for 10 seconds to the flexible device carrier sheet formed by peeling the peeling sheet in an environment of 23°C and a relative humidity of 50%, it is preferable that the surface resistivity of the exposed surface of the adhesive layer is 1×10 ⁷ Ω/sq or more and 1×10 ¹¹ Ω/sq or less (invention 5).

In the above inventions (inventions 1 to 5), when a voltage of 100 V is applied to the substrate for 10 seconds in an environment of 23°C and a relative humidity of 50%, it is preferable that the surface resistivity of the surface of the substrate opposite to the adhesive layer is 1×10 ⁷ Ω/sq or more and 1×10 ¹¹ Ω/sq or less (invention 6).

In the above inventions (inventions 1 to 6), when a voltage of 100 V is applied to the peeling sheet for 10 seconds in an environment of 23°C and a relative humidity of 50%, it is preferable that the surface resistivity of the surface on the adhesive layer side of the peeling sheet is 1×10 ⁷ Ω/sq or more and 1×10 ¹¹ Ω/sq or less (invention 7).

In the above inventions (inventions 1 to 7), when a voltage of 100 V is applied to the peeling sheet for 10 seconds in an environment of 23°C and a relative humidity of 50%, it is preferable that the surface resistivity of the side of the peeling sheet opposite to the adhesive layer is 1×10 ⁷ Ω/sq or more and 1×10 ¹¹ Ω/sq or less (invention 8).

In the above inventions (inventions 1 to 8), it is preferable that the haze value of the carrier sheet for the flexible device excluding the peeling sheet is 8% or less (invention 9).

The carrier sheet according to the present invention has excellent antistatic properties in each process and can suppress the haze value to a low level.

FIG. 1 is a cross-sectional view of a carrier sheet for a flexible device according to one embodiment of the present invention.
Figure 2 is a drawing (color) showing images and graphs obtained from a percussion test.

Hereinafter, embodiments of the present invention will be described.

A carrier sheet for a flexible device according to one embodiment of the present invention (hereinafter, sometimes simply referred to as a “carrier sheet”) is mainly used to transport a flexible device while protecting the surface of the flexible device during processes such as processing, laminating, and inspection of the flexible device.

The flexible device in this specification refers to a device having flexibility, such as an optical member or electronic member, and examples thereof include a flexible organic light-emitting diode (OLED) device, a flexible liquid crystal device, and among these, a flexible OLED device is preferable.

A carrier sheet according to the present embodiment comprises a substrate, an adhesive layer laminated on one surface side of the substrate, and a release sheet laminated on a surface of the adhesive layer opposite to the substrate, wherein all of the substrate, the adhesive layer, and the release sheet have antistatic properties.

According to the carrier sheet of the present embodiment, since the substrate, the adhesive layer, and the release sheet all have antistatic properties as described above, when the release sheet is peeled from the adhesive layer, or when the carrier sheet is peeled from the flexible device, or during a process such as processing, laminating, or inspection of the flexible device, or during transport, or when the carrier sheet is ejected, static electricity is unlikely to be generated, and dust or dirt in the air can be suppressed from adhering to the flexible device due to static electricity. In addition, since the substrate, the adhesive layer, and the release sheet each have antistatic properties, the amount of antistatic agent used in the adhesive layer can be reduced compared to, for example, a case where the antistatic properties of the entire adhesive layer are satisfied by a single layer. As a result, the haze value of the adhesive layer, and further, the haze value of the entire carrier sheet, can be suppressed low. As described above, a carrier sheet with a low haze value has high transparency and is suitable for luminescence inspection of flexible OLED devices, etc.

Hereinafter, a carrier sheet as an example of the present embodiment will be described with reference to the drawings.

As shown in Fig. 1, a carrier sheet (1) according to the present embodiment comprises a substrate (2), an adhesive layer (3), and a release sheet (4). The substrate (2) has a substrate film (21), and a first antistatic layer (22) formed on a surface of the substrate film (21) opposite to the adhesive layer (3) (the upper surface in Fig. 1). The release sheet (4) has a support (41), and has one or both of a second antistatic layer (42a) formed on a surface of the support (41) on the side of the adhesive layer (3) (the upper surface in FIG. 1) and a third antistatic layer (42b) formed on a surface of the support (41) opposite to the adhesive layer (3) (the lower surface in FIG. 1), and preferably has both of the second antistatic layer (42a) and the third antistatic layer (42b). In addition, the release sheet (4) has a release agent layer (43) at a position closest to the adhesive layer (3). The release layer (43) is provided on a surface of the second antistatic layer (42a) opposite to the support (41) when the second antistatic layer (42a) is present, and is provided on a surface of the support (41) on the adhesive layer (3) side when the second antistatic layer (42a) is not present. The adhesive layer (3) is laminated on the substrate (2) so as to be in contact with the substrate film (21). In addition, the adhesive layer (3) in the present embodiment contains an antistatic agent.

As one preferable mode of use of the carrier sheet (1) according to the present embodiment, there may be mentioned a mode in which the carrier sheet (1) is fed out from a winding roll of the carrier sheet (1), the release sheet (4) is peeled off, a flexible device is installed on the exposed adhesive layer (3), and while being fed, is processed, laminated, inspected, etc., and then the carrier sheet (1) is peeled off from the flexible device. In the above-described feeding step, in particular, the first antistatic layer (22) exhibits antistatic properties, and by providing the third antistatic layer (42b), the antistatic properties become even more excellent. During the process of processing, laminating, inspecting, etc. of the flexible device or during feeding, the first antistatic layer (22) can particularly suppress the generation of static electricity due to frictional electrification. Meanwhile, when the peeling sheet (4) is peeled from the carrier sheet (1), the antistatic property is exhibited particularly by the adhesive layer (3) containing the antistatic agent, and the antistatic property is further improved by the provision of the second antistatic layer (42a). In addition, when the carrier sheet (1) is peeled from the flexible device, the antistatic property is exhibited particularly by the adhesive layer (3) containing the antistatic agent.

In addition, one side of the second antistatic layer (42a) and the third antistatic layer (42b) of the peeling sheet (4) may be omitted. However, since both sides of the second antistatic layer (42a) and the third antistatic layer (42b) are formed on the peeling sheet (4), the antistatic property of the carrier sheet (1) becomes more excellent.

In addition, in the carrier sheet (1) according to the present embodiment, since the adhesive layer (3) has antistatic properties, an antistatic layer is unnecessary on the adhesive layer (3) side of the base film (21). However, an antistatic layer may be additionally formed on the adhesive layer (3) side of the base film (21).

1. Each absence

(1) Description

(1-1) Substrate film

The substrate film (21) is preferably made of a plastic film having properties suitable for the protection and return of the flexible device and for each process. As such a substrate film (21), for example, a plastic film made of a resin such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyimide, polyether imide, polycarbonate, polymethyl pentene, polyphenylene sulfide, or a liquid crystal polymer is preferable, and the film may be a single-layer film or a film in which multiple layers of the same or different types are laminated. Among the above, a polyethylene terephthalate film is particularly preferable in terms of handling properties, transparency, and cost for a flexible device.

Here, when the flexible device being the returned article is a flexible OLED device, the luminescence inspection of the flexible OLED device is performed at a stricter level than the luminescence inspection of a liquid crystal device, etc., and therefore the carrier sheet (1) is required to have high transparency. As described above, the carrier sheet (1) according to the present embodiment can suppress the haze value low, and is therefore suitable for the luminescence inspection described above. However, in order to further increase the transparency of the carrier sheet (1), the base film (21) is preferably made of a plastic film that does not contain a filler. Thereby, the carrier sheet (1) has higher transparency, and becomes more suitable for the luminescence inspection of a flexible OLED device.

In addition, the plastic film may contain additives such as fillers, heat resistance improvers, ultraviolet absorbers, and refractive index adjusters, as long as the above-described effects of the present embodiment are not impaired.

In the above-described base film (21), surface treatment by an oxidation method, a roughening method, or a primer treatment can be performed, if desired, for the purpose of improving adhesion with the first antistatic layer (22) and/or the adhesive layer (3). Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, ultraviolet irradiation treatment, and the like, and examples of the roughening method include sandblasting, thermal spraying, and the like. These surface treatment methods are appropriately selected depending on the type of the base film (21).

Considering the handling properties when the flexible device is used as a transported object, especially the workability of peeling from the flexible device, the thickness of the substrate film (21) is preferably 25 µm or more, and considering the scratch resistance, it is more preferably 50 µm or more, and even more preferably 80 µm or more. In addition, similarly considering the handling properties and cost, the thickness is preferably 188 µm or less, especially preferably 150 µm or less, and even more preferably 125 µm or less.

(1-2) Anti-static layer

The first antistatic layer (22) is not particularly limited as long as it is made of a material that can impart the desired antistatic property to the base film (21) and has the desired transparency. As such a first antistatic layer (22), it is preferable that it is a layer made of a composition for an antistatic layer containing a conductive polymer and a binder resin, for example.

As the conductive polymer, any one of the conventionally known conductive polymers can be selected and used, but among them, a polythiophene-based, polyaniline-based or polypyrrole-based conductive polymer is preferable. The conductive polymer may be used alone or in combination of two or more types.

As the conductive polymer of the polythiophene series, there can be mentioned, for example, polythiophene, poly(3-alkylthiophene), poly(3-thiophene-β-ethanesulfonic acid), a mixture of polyalkylenedioxythiophene and polystyrene sulfonate (PSS) (including doped ones), etc. Of these, a mixture of polyalkylenedioxythiophene and polystyrene sulfonate is preferable. As the polyalkylenedioxythiophene, there can be mentioned poly(3,4-ethylenedioxythiophene) (PEDOT), polypropylenedioxythiophene, poly(ethylene/propylene)dioxythiophene, etc., and of these, poly(3,4-ethylenedioxythiophene) is preferable. That is, of the above, a mixture of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate (PEDOT doped with PSS) is particularly preferable.

As conductive polymers of the polyaniline series, examples thereof include polyaniline, polymethylaniline, and polymethoxyaniline. As conductive polymers of the polypyrrole series, examples thereof include polypyrrole, poly-3-methylpyrrole, and poly-3-octylpyrrole.

The content of the conductive polymer in the composition for an antistatic layer is preferably 0.1 to 30 mass%, particularly preferably 0.2 to 20 mass%, and more preferably 0.3 to 10 mass%. When the content of the conductive polymer is within the above range, good antistatic performance is obtained, and furthermore, the strength of the antistatic layer formed from the composition for an antistatic layer is sufficient.

As the binder resin used in the composition for the above-mentioned antistatic layer, it is preferable to contain as a main component at least one selected from the group consisting of a polyester resin, a urethane resin, and an acrylic resin. These resins may be thermosetting compounds or ultraviolet-curable compounds, but in order to make them ultraviolet-curable, it is necessary to replace the solvent from an aqueous system to an organic solvent system, so from the viewpoints of the number of processes and cost, a thermosetting compound is preferable. Among the above, a thermosetting polyester resin is preferable because of its high adhesion to a plastic film, and a polyester resin having a reactive group that reacts with a crosslinking agent, such as a hydroxyl group, is particularly preferable.

The composition for the anti-static layer may contain, in addition to the above components, a crosslinking agent, a leveling agent, an anti-fouling agent, etc.

As a crosslinking agent, any agent capable of crosslinking the above resin may be used. For example, if the above resin has a hydroxyl group as a reactive group, it is preferable to use an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an amine-based crosslinking agent, a melamine-based crosslinking agent, etc.

The content of the crosslinking agent is preferably 1 to 50 parts by mass, particularly preferably 5 to 40 parts by mass, and more preferably 10 to 30 parts by mass, per 100 parts by mass of the binder resin.

As a leveling agent, for example, a dimethylsiloxane-based compound, a fluorine-based compound, a surfactant, etc. can be used. In the first antistatic layer (22), it is preferable to use a surfactant from the viewpoint of adhesion to the adhesive layer (3). By containing a leveling agent in the composition for an antistatic layer, the smoothness of the antistatic layer (42a, 42b) can be improved, and the transparency of the substrate (2) becomes higher.

The content of the leveling agent in the composition for the antistatic layer is preferably 0.1 to 10 mass%, particularly preferably 0.2 to 5 mass%, and more preferably 0.5 to 3 mass%.

The thickness of the first antistatic layer (22) is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more, in consideration of antistatic performance. In addition, from the viewpoints of strength and cost, the thickness is preferably 200 nm or less, particularly preferably 150 nm or less, and even more preferably 100 nm or less.

(1-3) Physical properties of the material

(1-3-1) Surface resistivity

In an environment of 23°C and a relative humidity of 50%, when a voltage of 100 V is applied to the substrate (2) for 10 seconds, the surface resistivity of the side of the substrate (2) opposite to the adhesive layer (3) is preferably 1×10 ¹¹ Ω/sq or less, particularly preferably 5×10 ¹⁰ Ω/sq or less, and more preferably 1×10 ¹⁰ Ω/sq or less. Since the upper limit of the surface resistivity is as above, the generation of static electricity can be more effectively suppressed when the carrier sheet (1) is fed out from the winding roll of the carrier sheet (1), or during processes such as processing, laminating, and inspection of a flexible device, or during conveyance. In addition, the lower limit of the surface resistivity is not particularly limited, but is usually preferably 1×10 ⁷ Ω/sq or more, particularly preferably 5×10 ⁷ Ω/sq or more, and more preferably 1×10 ⁸ Ω/sq or more.

In addition, the surface resistivity in this specification is a value measured in accordance with JIS K6911, and the details of the method for measuring the surface resistivity are as shown in the test example described below.

(1-3-2) Haze value

The haze value of the substrate (2) is preferably 8% or less, particularly preferably 4% or less, and more preferably 1% or less. When the haze value of the substrate (2) is as described above, the transparency of the carrier sheet (1) adhered to the returned object becomes high, and it becomes suitable for the luminescence inspection of the flexible OLED device. In addition, the lower limit of the haze value is not particularly limited, and it is particularly preferable that it is 0%. Here, the haze value in this specification is a value measured in accordance with JIS K7136:2000.

(2) Adhesive layer

The adhesive layer (3) in the present embodiment contains an antistatic agent. Specifically, the adhesive layer (3) is formed from an adhesive containing an antistatic agent.

(2-1) Adhesive

As the adhesive constituting the adhesive layer (3), it is preferable to select an adhesive that is suitable for adhesion to a transported object (flexible device) and peeling from the transported object. In particular, it is preferable to select an adhesive having excellent re-peelability so that the carrier sheet (1) can be easily peeled from the flexible device.

Examples of the types of adhesives include acrylic adhesives, silicone adhesives, urethane adhesives, and polyester adhesives. From the viewpoint of releasability, acrylic adhesives and silicone adhesives are preferable. However, when a general antistatic agent is added to a silicone adhesive, the transparency of the resulting adhesive layer (3) decreases due to low compatibility, and substrate adhesion also decreases. On the other hand, even when a general antistatic agent is added to an acrylic adhesive, the effect on compatibility as described above is relatively small. Therefore, an acrylic adhesive is particularly preferable. Hereinafter, an acrylic adhesive containing an antistatic agent will be described.

The acrylic adhesive in the present embodiment is preferably a crosslinked (cured) adhesive composition containing one or more (meth)acrylic acid ester copolymers and an antistatic agent, preferably further containing a crosslinking agent. In addition, in the present specification, (meth)acrylic acid ester means both an acrylic acid ester and a methacrylic acid ester. Other similar terms also apply.

From the viewpoint of releasability, the above-mentioned adhesive composition preferably contains a first (meth)acrylic acid ester copolymer (A) having a relatively large weight average molecular weight and a second (meth)acrylic acid ester copolymer (B) having a relatively small weight average molecular weight as (meth)acrylic acid ester copolymers. The adhesive composition is preferably an adhesive composition comprising, in particular, a first (meth)acrylic acid ester copolymer (A) containing, as monomer units constituting the copolymer, a monomer having a hydroxyl group and a monomer having a carboxyl group, a second (meth)acrylic acid ester copolymer (B) containing, as monomer units constituting the copolymer, a monomer having a hydroxyl group and a monomer having a carboxyl group and having a weight average molecular weight smaller than the weight average molecular weight of the first (meth)acrylic acid ester copolymer (A), an isocyanate crosslinking agent (C), and an antistatic agent (D). In addition, the adhesive composition has a ratio of a monomer having a hydroxyl group in the monomer constituting the second (meth)acrylic acid ester copolymer (B) greater than a ratio of a monomer having a hydroxyl group in the monomer constituting the first (meth)acrylic acid ester copolymer (A), and the sum of the mass parts of the monomers having a carboxyl group constituting the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) is 0.1 to 1.0 mass parts with respect to 100 mass parts in total of the mass parts of the monomers constituting the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B), and the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) are It is preferable that the adhesive composition (hereinafter sometimes referred to as “adhesive composition P”) have a mixing ratio based on mass in the copolymer (B) of 90:10 to 10:90.

The adhesive obtained from the above adhesive composition P is presumed to exhibit sufficient adhesion when processing and conveying a flexible device, because the first (meth)acrylic acid ester copolymer (A) having a longer chain length has a relatively small number of crosslinking points, a higher degree of freedom, and is easy to deform. On the other hand, when re-peeling, the movement of the copolymer (A) is restricted by the second (meth)acrylic acid ester copolymer (B) having a large number of crosslinking points, and it is difficult to deform more than a predetermined amount, so it is presumed to exhibit relatively small adhesion. As a result, the carrier sheet (1) is brought into close contact with the flexible device during the process, and further, the carrier sheet (1) is easily peeled from the flexible device after the process.

In the adhesive composition P, the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) each contain a monomer having a carboxyl group as a monomer unit constituting the copolymer. The monomer having a carboxyl group acts as a crosslinking accelerator. Therefore, in the adhesive composition P, since the monomer having a carboxyl group is included in the copolymer (A) and the copolymer (B) as a monomer constituting unit, the use of other crosslinking accelerators such as a tin catalyst can be omitted.

In the adhesive composition P, the total number of parts by mass of the monomers having a carboxyl group which constitute the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) is preferably 0.1 to 1.0 parts by mass, particularly preferably 0.15 to 0.8 parts by mass, and more preferably 0.3 to 0.6 parts by mass, with respect to 100 parts by mass of the total number of parts by mass of the monomers having a carboxyl group. When the total number of parts by mass of the monomers having a carboxyl group is 1.0 part by mass or less, the crosslinking reaction is excessively promoted, which prevents the adhesive composition P from gelling before formation of an adhesive, thereby ensuring sufficient pot life. Meanwhile, when the total mass parts of monomers having a carboxyl group is 0.1 mass parts or more, the effect of promoting crosslinking can be obtained.

The first (meth)acrylic acid ester copolymer (A) preferably contains 0.01 to 2.0 mass% of a monomer having a carboxyl group as a monomer unit constituting the copolymer, particularly preferably 0.05 to 1.5 mass%, and more preferably 0.3 to 1.0 mass%. When the content of the monomer is 2.0 mass% or less, the pot life of the adhesive composition becomes more excellent. Furthermore, when the content of the monomer is 0.01 mass% or more, the effect of promoting crosslinking by the carboxyl group is sufficiently obtained, and thereby, a structure in which the copolymer (A) is bonded via a hydroxyl group to a part of the crosslinked structure formed mainly of the copolymer (B) is satisfactorily formed, and the high-speed adhesive strength of the obtained adhesive sheet can be suppressed to be low.

The second (meth)acrylic acid ester copolymer (B) preferably contains 0.01 to 0.99 mass% of a monomer having a carboxyl group as a monomer unit constituting the copolymer, particularly preferably 0.05 to 0.8 mass%, and more preferably 0.2 to 0.6 mass%. When the content of the monomer is 0.99 mass% or less, the pot life of the adhesive composition becomes more excellent. Furthermore, when the content of the monomer is 0.01 mass% or more, the effect of promoting crosslinking by the carboxyl group is obtained, whereby a good crosslinked structure is formed, and the obtained adhesive sheet becomes more excellent in re-peelability.

As monomers having a carboxyl group, examples thereof include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, and vinyl acetate. These may be used alone or in combination of two or more. From the viewpoint of promoting crosslinking, it is particularly preferable to use acrylic acid as the monomer having a carboxyl group.

In the adhesive composition P, the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) each contain a monomer having a hydroxyl group as a monomer unit constituting the copolymer. Since the adhesive composition according to the present embodiment contains an isocyanate-based crosslinking agent (C) as a crosslinking agent, a hydroxyl group having excellent reactivity with isocyanate groups acts as a crosslinking point in the copolymers (A) and (B).

In the adhesive composition P, it is preferable that the proportion of the monomer having a hydroxyl group in the monomers constituting the second (meth)acrylic acid ester copolymer (B) is greater than the proportion of the monomer having a hydroxyl group in the monomers constituting the first (meth)acrylic acid ester copolymer (A). In this way, since the copolymer (B) having a lower molecular weight has a larger number of hydroxyl groups, the copolymer (B) easily binds the copolymer (A) during re-peeling, and the adhesive strength is sufficiently reduced.

The first (meth)acrylic acid ester copolymer (A) preferably contains 0.01 to 5 mass% of a monomer having a hydroxyl group as a monomer unit constituting the copolymer, particularly preferably 0.05 to 1 mass%, and more preferably 0.1 to 0.5 mass%.

The second (meth)acrylic acid ester copolymer (B) preferably contains 0.1 to 10 mass% of a monomer having a hydroxyl group as a monomer unit constituting the copolymer, particularly preferably 0.6 to 8 mass%, and more preferably 1.1 to 5 mass%.

As the monomer having a hydroxyl group, examples thereof include (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 2-hydroxybutyl, (meth)acrylic acid 3-hydroxybutyl, (meth)acrylic acid 4-hydroxybutyl, and the like (meth)acrylic acid hydroxyalkyl esters. These may be used alone or in combination of two or more. In particular, since 4-hydroxybutyl acrylate exhibits high reactivity in a crosslinking reaction, from the viewpoint of releasability, it is preferable to use 4-hydroxybutyl acrylate as the monomer having a hydroxyl group.

In the adhesive composition P, the second (meth)acrylic acid ester copolymer (B) preferably contains, as a monomer unit constituting the copolymer, a (meth)acrylic acid ester having an alkylene oxide chain (hereinafter, sometimes referred to as “alkylene oxide chain-containing acrylic acid ester”). The alkylene of the alkylene oxide chain is preferably an alkylene having 2 to 4 carbon atoms, and particularly preferably ethylene oxide having 2 carbon atoms. In this case, the average added mole number of the alkylene oxide chain in one molecule of the alkylene oxide chain-containing acrylic acid ester is preferably 1 to 20 mol, particularly preferably 3 to 15 mol, and more preferably 6 to 10 mol. Since the second (meth)acrylic acid ester copolymer (B) contains an alkylene oxide chain-containing (meth)acrylic acid ester as a monomer unit, when an ion-conductive antistatic agent (D) is added to the adhesive, the mobility of the antistatic agent (D) in the adhesive increases, thereby further obtaining the effect of the antistatic agent (D). In addition, the first (meth)acrylic acid ester copolymer (A) may contain an alkylene oxide chain-containing (meth)acrylic acid ester as a monomer unit constituting the copolymer; however, since the copolymer (A) has a high molecular weight, the viscosity of the adhesive composition may become too high, which may deteriorate processability. Therefore, the alkylene oxide chain-containing (meth)acrylic acid ester is preferably contained only in the second (meth)acrylic acid ester copolymer (B). In addition, it is preferable that the terminal of the alkylene oxide chain is protected with an alkyl group having 1 to 4 carbon atoms so as not to react with the crosslinking agent (C). In addition, from the viewpoint of further demonstrating the effect of adding the antistatic agent (D) and simultaneously achieving compatibility with the copolymer (A), it is preferable that the copolymer (B) contains 1 to 30 mass% of an alkylene oxide chain-containing (meth)acrylic acid ester as a monomer unit, more preferably 5 to 20 mass%, and particularly preferably 10 to 17 mass%.

In the adhesive composition P, it is preferable that the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) each contain, as a monomer unit constituting the copolymer, a (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group. Thereby, an adhesive exhibiting desired adhesiveness can be obtained.

Examples of (meth)acrylic acid alkyl esters having 1 to 20 carbon atoms in the alkyl group (hereinafter sometimes referred to as “(meth)acrylic acid alkyl esters”) include methyl acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, etc. Among these, from the viewpoint of obtaining more desirable adhesiveness, it is preferable to use (meth)acrylic acid alkyl esters having 4 to 8 carbon atoms in the alkyl group, and examples thereof include butyl acrylate and 2-ethylhexyl acrylate. In particular, it is preferable to use both butyl acrylate and 2-ethylhexyl acrylate.

From the viewpoint of ensuring the blending ratio of the monomer having a hydroxyl group and the monomer having a carboxyl group described above while imparting adhesiveness to the obtained adhesive, the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) each preferably contain 60 to 99.8 mass% of a (meth)acrylic acid alkyl ester as a monomer constituent unit. Furthermore, the copolymer (A) more preferably contains 85 to 99.6 mass% of a (meth)acrylic acid alkyl ester as a monomer constituent unit. Furthermore, the copolymer (B) more preferably contains 65 to 85 mass% of a (meth)acrylic acid alkyl ester as a monomer constituent unit.

When using both 2-ethylhexyl acrylate and butyl acrylate as the (meth)acrylic acid alkyl ester, from the viewpoint of obtaining a high level of compatibility between adhesion and releasability during transportation, etc., the ratio of 2-ethylhexyl acrylate to butyl acrylate in each of the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) is preferably 95:5 to 50:50 in mass conversion, particularly preferably 90:10 to 60:40. In addition, in the copolymer (A), the ratio is more preferably 74:26 to 65:35 in mass conversion. In addition, in the copolymer (B), the ratio is more preferably 85:15 to 76:24 in mass conversion.

In the adhesive composition P, the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) may contain other monomers as monomer units constituting the polymer, if desired. As the other monomer, a monomer that does not contain a reactive functional group is preferable in order not to interfere with the action of a monomer having a carboxyl group and a monomer having a hydroxyl group. Examples of such other monomers include (meth)acrylic acid esters containing an alkoxyalkyl group such as (meth)acrylic acid methoxymethyl, (meth)acrylic acid methoxyethyl, (meth)acrylic acid ethoxymethyl, (meth)acrylic acid ethoxyethyl, etc.; (meth)acrylic acid esters having an aromatic ring such as (meth)acrylic acid phenyl, (meth)acrylic acid benzyl, etc.; acrylic acid esters such as silicone (meth)acrylate, fluorine (meth)acrylate, etc.; non-crosslinked acrylamides such as acrylamide, methacrylamide, and acryloylmorpholine; non-crosslinked tertiary amino group-containing (meth)acrylic acid esters such as (meth)acrylic acid N,N-dimethylaminoethyl, (meth)acrylic acid N,N-dimethylaminopropyl, etc.; vinyl such as vinyl acetate, N-vinylpyrrolidone, and styrene. Monomers, etc. can be used alone or in combination of two or more.

In the adhesive composition P, the above-mentioned first (meth)acrylic acid ester copolymer (A) may be used alone, or two or more types may be used in combination. In addition, the above-mentioned second (meth)acrylic acid ester copolymer (B) may be used alone, or two or more types may be used in combination.

In the adhesive composition P, as described above, in addition to the second (meth)acrylic acid ester copolymer (B) having more crosslinking points than the first (meth)acrylic acid ester copolymer (A), the weight average molecular weight of the second (meth)acrylic acid ester copolymer (B) is smaller than the weight average molecular weight of the first (meth)acrylic acid ester copolymer (A). As a result, both releasability and adhesiveness during return of a flexible device can be effectively achieved.

The weight average molecular weight of the first (meth)acrylic acid ester copolymer (A) is preferably 50,000 to 500,000, particularly preferably 100,000 to 400,000, and more preferably 150,000 to 300,000. In addition, the weight average molecular weight in this specification is a value converted to standard polystyrene measured by the gel permeation chromatography (GPC) method.

The weight average molecular weight of the second (meth)acrylic acid ester copolymer (B) is preferably 0.2 to 100,000, particularly preferably 0.5 to 50,000, and more preferably 10,000 to 20,000.

In the adhesive composition P, the mass-based blending ratio of the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) is preferably 90:10 to 10:90. In particular, the blending amount of the second (meth)acrylic acid ester copolymer (B) is preferably greater than the blending amount of the first (meth)acrylic acid ester copolymer (A). Specifically, the blending ratio is preferably 45:55 to 10:90, particularly preferably 42:58 to 20:80, and more preferably 40:60 to 30:70. By increasing the amount of the second (meth)acrylic acid ester copolymer (B), a high level of effect is obtained in which sufficient adhesion is exhibited to prevent peeling during return and processing of the flexible device, while the flexible device can be peeled off without leaving any residue after a series of processes are completed.

The isocyanate crosslinking agent (C) contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and biuret forms, isocyanurate forms, and adducts which are reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, the isocyanurate-type trimer of 1,6-hexamethylene diisocyanate is preferably used. These may be used alone or in combination of two or more.

The content of the isocyanate crosslinking agent (C) is preferably 0.1 to 10 parts by mass, particularly preferably 1 to 8 parts by mass, and more preferably 2 to 6 parts by mass, relative to 100 parts by mass of the total of the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B).

As the antistatic agent (D), any agent capable of imparting antistatic properties to the resulting adhesive may be used, and examples thereof include ionic compounds, nonionic compounds, etc., but among these, an ionic compound having ionic conductivity is preferable. The ionic compound may be a liquid or a solid at room temperature, but from the viewpoint of easily exhibiting stable antistatic properties even when exposed to durable conditions, it is preferable that the ionic compound is a solid at room temperature. Here, the ionic compound in the present specification refers to a compound in which cations and anions are mainly connected by electrostatic attraction.

As the ionic compound, a nitrogen-containing salt, a sulfur-containing salt, a phosphorus-containing salt, an alkali metal salt or an alkaline earth metal salt is preferable. From the viewpoint of excellent durability of the obtained adhesive, a nitrogen-containing salt or an alkali metal salt is particularly preferable, and a nitrogen-containing salt is more preferable. The nitrogen-containing salt is preferably an ionic compound composed of a nitrogen-containing heterocyclic cation and its counter anion.

As the nitrogen-containing heterocyclic skeleton of the nitrogen-containing heterocyclic cation, a pyridine ring, a pyrimidine ring, an imidazole ring, a triazole ring, an indole ring, etc. are preferable, and among them, a pyridine ring is preferable. In addition, as the cation of the alkali metal salt, a lithium ion, a potassium ion, or a sodium ion is preferable, and a lithium ion or a potassium ion is particularly preferable.

Meanwhile, as anions constituting the above ionic compound, halogenated phosphate anions or sulfonylimide-based anions can be preferably mentioned. As halogenated phosphate anions, hexafluorophosphate and the like can be preferably mentioned. In addition, as sulfonylimide-based anions, bis(fluoroalkylsulfonyl)imide or bis(fluorosulfonyl)imide and the like can be preferably mentioned.

Specific examples of the above antistatic agent (D) include pyridinium hexafluorophosphate compounds such as N-butyl-4-methylpyridinium hexafluorophosphate, N-hexyl-4-methylpyridinium hexafluorophosphate, N-octylpyridinium hexafluorophosphate, N-octyl-4-methylpyridinium hexafluorophosphate, N-dodecylpyridinium hexafluorophosphate, N-tetradecylpyridinium hexafluorophosphate, N-hexadecylpyridinium hexafluorophosphate, N-dodecyl-4-methylpyridinium hexafluorophosphate, N-tetradecyl-4-methylpyridinium hexafluorophosphate, and N-hexadecyl-4-methylpyridinium hexafluorophosphate; Examples thereof include fluorosulfonylimide compounds, such as N-decylpyridinium bis(fluorosulfonyl)imide, 1-ethylpyridinium bis(fluorosulfonyl)imide, 1-butylpyridinium bis(fluorosulfonyl)imide, 1-hexylpyridinium bis(fluorosulfonyl)imide, 1-butyl-3-methylpyridinium bis(fluorosulfonyl)imide, 1-butyl-4-methylpyridinium bis(fluorosulfonyl)imide, 1-hexyl-3-methylpyridinium bis(fluorosulfonyl)imide, 1-butyl-3,4-dimethylpyridinium bis(fluorosulfonyl)imide, potassium bis(fluorosulfonyl)imide, lithium bis(fluorosulfonyl)imide, potassium bis(fluoromethanesulfonyl)imide, and lithium bis(fluoromethanesulfonyl)imide. Among these, from the viewpoint of compatibility with the (meth)acrylic acid ester copolymer (A), N-butyl-4-methylpyridinium hexafluorophosphate, N-hexyl-4-methylpyridinium hexafluorophosphate, N-octyl-4-methylpyridinium hexafluorophosphate, N-decylpyridinium bis(fluorosulfonyl)imide, and potassium bis(fluorosulfonyl)imide are preferable, and in particular, N-octyl-4-methylpyridinium hexafluorophosphate and potassium bis(fluorosulfonyl)imide are preferable. The above antistatic agents (D) may be used alone or in combination of two or more.

When combining two or more types, it is preferable to use a combination of a pyridinium hexafluorophosphate-based compound and a fluorosulfonylimide-based compound, and it is particularly preferable to use N-octyl-4-methylpyridinium hexafluorophosphate and potassium bis(fluorosulfonyl)imide. Thereby, the antistatic property of the obtained adhesive is more excellent. The mixing ratio (by mass) of the pyridinium hexafluorophosphate-based compound and the fluorosulfonylimide-based compound is preferably 90:10 to 10:90, particularly preferably 80:20 to 20:80, and more preferably 75:25 to 55:45.

The content of the antistatic agent (D) in the adhesive composition P is preferably 0.1 parts by mass or more, particularly preferably 0.5 parts by mass or more, further preferably 1.0 parts by mass or more, and most preferably 1.5 parts by mass or more, per 100 parts by mass of the (meth)acrylic acid ester copolymer (A). In addition, the content is preferably 10 parts by mass or less, particularly preferably 8 parts by mass or less, and further preferably 5 parts by mass or less. In the carrier sheet (1) according to the present embodiment, since each of the substrate (2), the adhesive layer (3), and the release sheet (4) has antistatic properties, the content of the antistatic agent (D) in the adhesive composition P can be made relatively small as described above. Therefore, the haze value of the obtained adhesive layer (3), and further, the haze value of the entire carrier sheet (1), can be suppressed low. In addition, since the content of the antistatic agent (D) is within the above range, antistatic properties can be effectively exhibited, and deterioration of physical properties such as durability and warping resistance can be prevented.

The adhesive composition P may contain a plasticizer. By containing a plasticizer, the adhesive strength of the resulting adhesive can be easily controlled, and thus excellent releasability can be achieved.

Specific examples of plasticizers include tributyl acetyl citrate and tetraethylene glycol dimethyl ether.

The content of the plasticizer is preferably 1 to 20 parts by mass, particularly preferably 3 to 15 parts by mass, and more preferably 6 to 12 parts by mass, relative to 100 parts by mass of the total of the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B).

To the adhesive composition P, various additives commonly used in acrylic adhesives, such as tackifiers, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, and refractive index adjusters, can be added, as desired.

In addition, it is preferable that the adhesive composition P does not contain a tin compound, and in particular, it is preferable that it does not contain an organic tin compound. In the adhesive composition P, since crosslinking is promoted by a monomer having a carboxyl group, there is no need to contain a tin compound such as a tin catalyst as a crosslinking accelerator. Since the adhesive composition P does not contain a tin compound, an adhesive with a reduced burden on the environment can be obtained.

The adhesive composition P can be prepared, for example, as follows.

That is, first, (meth)acrylic acid ester copolymers (A) and (B) are prepared separately, preferably in a polymerization solvent described below, by a conventional radical polymerization method. Next, solutions of the two obtained copolymers are mixed, and a dilution solvent is added so that the solid content concentration becomes 10 to 40 mass%. Thereafter, an isocyanate crosslinking agent (C), an antistatic agent (D), and a plasticizer or additive as desired are added, and sufficient mixing is performed to obtain an adhesive composition (application solution) diluted with a solvent.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve.

In addition, it is preferable that the adhesive composition P be manufactured by a series of polymerizations as shown below.

Specifically,

(1) In a mixture (a) containing a monomer constituting the first (meth)acrylic acid ester copolymer (A), the first (meth)acrylic acid ester copolymer (A) is manufactured by radical polymerization at a conversion rate of 50 to 90%,

(2) A mixture solution (b) containing a monomer constituting a second (meth)acrylic acid ester copolymer (B) is added, and a monomer remaining during polymerization of the monomer and the first (meth)acrylic acid ester copolymer (A) is radically copolymerized in the presence of the first (meth)acrylic acid ester copolymer (A), preferably at a conversion ratio of 70 to 100%, to produce a second (meth)acrylic acid ester copolymer (B), and then,

(3) Add an isocyanate crosslinking agent (C), an antistatic agent (D), and, if desired, a plasticizer and various additives.

The monomers constituting the first (meth)acrylic acid ester copolymer (A) contained in the mixed solution (a) are as described above. In addition, the contents of the monomer having a carboxyl group, the monomer having a hydroxyl group, and the (meth)acrylic acid alkyl ester in the mixed solution (a) can be said to be the same as the contents described above as monomer units constituting the first (meth)acrylic acid ester copolymer (A), respectively.

The monomers constituting the second (meth)acrylic acid ester copolymer (B) contained in the mixed solution (b) are as described above. In addition, the contents of the monomer having a carboxyl group, the monomer having a hydroxyl group, the (meth)acrylic acid ester containing an alkylene oxide chain, and the (meth)acrylic acid alkyl ester in the mixed solution (b) can be said to be the same as the contents described above as monomer units constituting the second (meth)acrylic acid ester copolymer (B), respectively.

The mixing ratio of the mixed solution (a) and the mixed solution (b) is preferably 90:10 to 10:90 in terms of mass. In particular, it is preferable that the mixing amount of the mixed solution (b) is greater than that of the mixed solution (a), and for example, the mixing ratio is preferably 45:55 to 10:90, particularly preferably 42:58 to 20:80, and more preferably 40:60 to 30:70.

The blending amount of the isocyanate crosslinking agent (C) and the plasticizer may be the same as the amount described above as the content in the adhesive composition P, respectively. In this case, the isocyanate crosslinking agent (C) or the plasticizer in the amount described above can be used with respect to 100 parts by mass of the total of the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) produced in the step (2).

The above-mentioned serial polymerization can be carried out by a solution polymerization method or the like, using a polymerization initiator as desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc., and two or more types may be used in combination.

Examples of polymerization initiators include azo compounds, organic peroxides, etc., and two or more types may be used in combination. Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane 1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), 2,2'-azobis[2-(2-imidazolin-2-yl)propane], etc.

Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl)peroxydicarbonate, t-butylperoxyneodecanoate, t-butylperoxypivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionyl peroxide, and diacetyl peroxide.

The concentration and viscosity of the coating solution of the adhesive composition prepared as described above may be within a coatable range and are not particularly limited, and may be appropriately selected depending on the situation. For example, the adhesive composition P is diluted to a concentration of 10 to 40 mass%. In addition, the addition of a dilution solvent or the like is not a necessary condition for obtaining the coating solution, and if the adhesive composition P has a coatable viscosity, etc., the dilution solvent may not be added.

The preferred adhesive constituting the adhesive layer (3) is one formed by crosslinking the adhesive composition P. Crosslinking of the adhesive composition P can be performed by heat treatment. In addition, this heat treatment can also serve as a drying treatment when volatilizing a dilution solvent of the adhesive composition P, etc.

When heat treatment is performed, the heating temperature is preferably 50 to 150°C, and particularly preferably 70 to 120°C. In addition, the heating time is preferably 30 seconds to 3 minutes, and particularly preferably 50 seconds to 2 minutes. In addition, after heat treatment, it is particularly preferable to provide a curing period of about 1 to 2 weeks at room temperature (e.g., 23°C, 50% RH).

By the above-mentioned heat treatment (and curing), the first (meth)acrylic acid ester copolymer (A) and the second (meth)acrylic acid ester copolymer (B) are crosslinked by the isocyanate-based crosslinking agent (C), thereby forming a three-dimensional network structure. In particular, since the second (meth)acrylic acid ester copolymer (B) has many crosslinking points, it is presumed that crosslinking between the second (meth)acrylic acid ester copolymers (B) occurs preferentially.

As described above, when the adhesive layer (3) is formed from an acrylic adhesive containing an antistatic agent, the adhesive layer (3) has excellent adhesion to the substrate (2). As a result, the stability and reliability as a product are high, and further, when the carrier sheet (1) is peeled off from the flexible device, there is no concern that the adhesive layer (3) or the adhesive will remain on the flexible device side.

(2-2) Thickness

The thickness of the adhesive layer (3) is preferably 5 µm or more, particularly preferably 12 µm or more, and more preferably 17 µm or more. When the thickness of the adhesive layer (3) is 5 µm or more, good adhesion can be obtained. In addition, when the thickness of the adhesive layer (3) is 12 µm or more, even if foreign matter such as dust or dirt adheres between the adhesive layer (3) (adhesive surface) of the carrier sheet (1) and the flexible device, the foreign matter is embedded in the adhesive layer (3). As a result, the inflow of air caused by the foreign matter between the carrier sheet (1) and the flexible device is suppressed, and luminescence inspection, etc. can be performed without a problem.

Meanwhile, from the viewpoint of peelability, the thickness of the adhesive layer (3) is preferably 75 µm or less, particularly preferably 50 µm or less, and more preferably 30 µm or less.

(2-3) Properties of the adhesive layer

In an environment of 23℃ and a relative humidity of 50%, when a voltage of 100 V is applied for 10 seconds to a carrier sheet (1) formed by peeling a peeling sheet (4), the surface resistivity of the exposed surface (adhesive surface) of the adhesive layer (3) is preferably 1×10 ¹¹ Ω/sq or less as an upper limit, particularly preferably 5×10 ¹⁰ Ω/s or less, and more preferably 1×10 ¹⁰ Ω/s or less. Since the upper limit of the surface resistivity is as above, particularly when the peeling sheet (4) is peeled from the carrier sheet (1) or when the carrier sheet (1) is peeled from a flexible device, the generation of static electricity can be more effectively suppressed. In addition, the lower limit of the surface resistivity is not particularly limited, but is usually preferably 1×10 ⁷ Ω/sq or more, particularly preferably 5×10 ⁷ Ω/sq or more, and more preferably 1×10 ⁸ Ω/sq or more.

(3) Peeling sheet

(3-1) Support

As the support (41), any material that does not adversely affect the adhesive layer (3) is not particularly limited, and examples thereof include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polyethylene naphthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene vinyl acetate film, an ionomer resin film, an ethylene/(meth)acrylic acid copolymer film, an ethylene/(meth)acrylic acid ester copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, a fluororesin film, and the like. In addition, crosslinked films of these are also used. In addition, a laminated film of these may be used. Of the above, a polyethylene terephthalate film excellent in handling properties is preferable.

There is no particular limitation on the thickness of the support (41), but it is usually preferable that it is 15 to 100 ㎛, and particularly preferable that it is 25 to 75 ㎛.

(3-2) Anti-static layer

The second antistatic layer (42a) and the third antistatic layer (42b) are not particularly limited as long as they are made of a material that can impart the desired antistatic property to the release sheet (4). As the material of such antistatic layers (42a, 42b), it is preferable to use the same material as the first antistatic layer (22) of the substrate (2) described above. In addition, it is preferable that the thickness of the antistatic layers (42a, 42b) be the same as the thickness of the first antistatic layer (22) of the substrate (2).

Here, as described above, in the carrier sheet (1) according to the present embodiment, either the second antistatic layer (42a) or the third antistatic layer (42b) can be omitted. However, in the case of omission, it is preferable to omit the third antistatic layer (42b). If the second antistatic layer (42a) in contact with the adhesive layer (3) is present, the antistatic property can be effectively increased when the release sheet (4) is peeled from the adhesive layer (3).

(3-3) Peeling agent layer

There is no particular limitation on the release agent constituting the release agent layer (43), and any one of conventionally known ones can be appropriately selected and used depending on the type of the adhesive of the adhesive layer (3). Examples of such release agents include silicone resin-based, fluororesin-based, alkyd resin-based, olefin resin-based, acrylic-based, long-chain alkyl group-containing compound-based, rubber-based, and the like. In particular, when the adhesive of the adhesive layer (3) is an acrylic-based adhesive, a silicone resin-based release agent is preferable from the viewpoint of the releasability of the adhesive layer (3). In addition, when the adhesive of the adhesive layer (3) is a silicone-based adhesive, the release agent layer (43) may be omitted.

The thickness of the release agent layer (43) is preferably 0.01 ㎛ or more as the lower limit, particularly preferably 0.03 ㎛ or more, and more preferably 0.05 ㎛ or more. With the lower limit of the thickness being the above, the function as the release agent layer (43) can be sufficiently exerted. In addition, the thickness of the release agent layer (43) is preferably 3 ㎛ or less as the upper limit, particularly preferably 1 ㎛ or less, and more preferably 0.5 ㎛ or less. With the upper limit of the thickness being the above, the curing of the release agent layer (43) can be sufficiently achieved.

(3-4) Properties of the peeling sheet

In an environment of 23°C and a relative humidity of 50%, when a voltage of 100 V is applied to the release sheet (4) for 10 seconds, the surface resistivity of the surface on the adhesive layer (3) side of the release sheet (4) (the exposed surface of the release agent layer (43)) is preferably 1×10 ¹¹ Ω/sq or less, particularly preferably 5×10 ¹⁰ Ω/sq or less, and more preferably 1×10 ¹⁰ Ω/sq or less. Since the upper limit of the surface resistivity is as described above, when the release sheet (4) is peeled from the carrier sheet (1) (the adhesive layer (3)), the generation of static electricity can be satisfactorily suppressed, and when the carrier sheet (1) is attached to a flexible device, dust or dirt in the air can be more effectively suppressed from adhering to the device. In addition, the lower limit of the surface resistivity is not particularly limited, but is usually preferably 1×10 ⁷ Ω/sq or more, particularly preferably 5×10 ⁷ Ω/sq or more, and more preferably 1×10 ⁸ Ω/sq or more.

In addition, in an environment of 23°C and a relative humidity of 50%, when a voltage of 100 V is applied to the release sheet (4) for 10 seconds, the surface resistivity of the side (exposed side of the third antistatic layer (42b)) opposite to the adhesive layer (3) of the release sheet (4) is preferably 1×10 ¹¹ Ω/sq or less, particularly preferably 5×10 ¹⁰ Ω/sq or less, and more preferably 1×10 ¹⁰ Ω/sq or less. Since the upper limit of the surface resistivity is as above, when the carrier sheet (1) is fed out from the winding roll of the carrier sheet (1), the generation of static electricity can be more effectively suppressed. In addition, the lower limit of the surface resistivity is not particularly limited, but is usually preferably 1×10 ⁷ Ω/sq or more, particularly preferably 5×10 ⁷ Ω/sq or more, and more preferably 1×10 ⁸ Ω/sq or more.

2. Manufacturing method of carrier sheet

(1) Manufacture of materials

In order to manufacture the substrate (2) in the present embodiment, as an example, a coating liquid containing an antistatic layer composition and, if desired, a solvent is applied to one side of a substrate film (21), and then dried and cured to form a first antistatic layer (22).

There is no particular limitation on the above solvent, and various solvents can be used. For example, ether solvents, alcohol solvents, and mixed solvents of alcohol solvents and purified water are used.

The coating solution of the composition for the antistatic layer may be applied by a conventional method, for example, by a gravure coating method, a bar coating method, a spray coating method, a spin coating method, a knife coating method, a roll coating method, a die coating method, etc.

When applying the above coating solution, it is preferable to heat-dry the coating film. The heating temperature for heat drying is preferably 70 to 140°C, and the heating time is preferably about 30 to 60 seconds.

(2) Manufacturing of peeling sheets

In order to manufacture the release sheet (4) in the present embodiment, as an example, a coating liquid containing an antistatic layer composition and a solvent as desired is applied to one surface of a support (41), and then dried and cured to form a second antistatic layer (42a). In addition, a coating liquid containing an antistatic layer composition and a solvent as desired is applied to the other surface of the support (41), and then dried and cured to form a third antistatic layer (42b). The method for forming the antistatic layers (42a, 42b) is the same as the method for forming the first antistatic layer (22) in the substrate (2) described above.

In addition, a release agent layer (43) is formed on the second antistatic layer (42a). The release agent layer (43) can be formed by applying a release agent coating solution containing a release agent and, if desired, a solvent, and then heating and drying as necessary. The method for applying the release agent coating solution is the same as the method for applying the antistatic layer coating solution.

(3) Manufacturing of carrier sheets

In order to manufacture the carrier sheet (1) according to the present embodiment, as an example, a coating solution containing an adhesive composition and, if desired, a diluent is applied to the surface opposite to the first antistatic layer (22) of the substrate (2), and heat treatment is performed to crosslink the adhesive composition, thereby forming a coating layer. Next, a release sheet (4) is attached to the coating layer so that a release agent layer (43) is in contact with it. When a curing period is required, a curing period is provided, and when a curing period is unnecessary, the coating layer becomes the adhesive layer (3) as it is. Thereby, the carrier sheet (1) is obtained. The conditions for the heat treatment and curing are as described above.

As a method for applying the coating solution of the above adhesive composition, for example, a bar coat method, a knife coat method, a roll coat method, a blade coat method, a die coat method, a gravure coat method, etc. can be used.

In addition, in the above-described manufacturing method, the adhesive composition coating liquid is applied to the substrate (2), but it may also be applied to the release sheet (4) and then the substrate (2) is bonded to the coating layer.

3. Properties of carrier sheet, etc.

(1) Total thickness

The total thickness of the laminate (in this embodiment, the laminate of the substrate (2) and the adhesive layer (3)) other than the peeling sheet (4) in the carrier sheet (1) according to the present embodiment is preferably 75 µm or more as the lower limit, particularly preferably 100 µm or more, and more preferably 125 µm or more. Since the lower limit of the total thickness is as described above, the flexible device to which the carrier sheet (1) is attached can be made easy to transport. In addition, even when an external force is applied to the carrier sheet (1) as a point load, the carrier sheet (1) is unlikely to be scratched, and thus has excellent scratch resistance. Therefore, the flexible device to which the carrier sheet (1) is attached can be well protected.

Meanwhile, the total thickness is preferably 300 ㎛ or less as an upper limit, particularly preferably 250 ㎛ or less, and more preferably 200 ㎛ or less. Since the upper limit of the total thickness is as described above, the handling property of the carrier sheet (1) becomes good, and also the cost can be prevented from becoming excessive.

(2) Stripping voltage

In an environment of 23°C and a relative humidity of 50%, when the peeling sheet (4) is manually peeled at a peeling speed of 2.0 m/min from the adhesive layer (3) in the carrier sheet (1) according to the present embodiment, the electrostatic potential (peeling voltage) measured at a position 2.0 cm from the exposed surface (adhesive surface) of the adhesive layer (3) 5 seconds after peeling is preferably 200 V or less, particularly preferably 150 V or less, and more preferably 100 V or less. Since the peeling voltage is the above, static electricity is unlikely to be generated when the peeling sheet (4) is peeled from the adhesive layer (3), and thus dust or dirt in the air can be effectively suppressed from adhering to the device due to static electricity. The lower limit of the peeling voltage is not particularly limited, but is preferably 0 V. In addition, the details of the method for measuring the peeling voltage are as shown in the test example described below.

In addition, in an environment of 23°C and a relative humidity of 50%, when the peeling sheet (4) is peeled manually at a peeling speed of 2.0 m/min from the adhesive layer (3) of the carrier sheet (1) according to the present embodiment, the electrostatic potential (peeling voltage) at a position 2.0 cm from the exposed surface on the adhesive layer (3) side of the peeling sheet (4) measured 5 seconds after peeling is preferably 200 V or less, particularly preferably 150 V or less, and more preferably 100 V or less. Since the peeling voltage is the above, static electricity is unlikely to be generated when the peeling sheet (4) is peeled from the adhesive layer (3), and dust or dirt in the air can be effectively suppressed from adhering to the device due to static electricity. The lower limit of the peeling voltage is not particularly limited, but is preferably 0 V.

(3) Adhesion

The adhesive strength of the carrier sheet (1) according to the present embodiment to soda-lime glass is preferably, as an upper limit, 300 mN/25 mm or less, particularly preferably, 250 mN/25 mm or less, and more preferably, 200 mN/25 mm or less. When the upper limit of the adhesive strength is as described above, the peelability of the carrier sheet (1) from the flexible device becomes excellent. On the other hand, the adhesive strength is preferably, as a lower limit, 50 mN/25 mm or more, particularly preferably, 75 mN/25 mm or more, and more preferably, 100 mN/25 mm or more. When the lower limit of the adhesive strength is as described above, the carrier sheet (1) attached to the flexible device is suppressed from being unintentionally peeled off during each process.

In addition, the adhesive strength of the carrier sheet (1) according to the present embodiment to the polyethylene terephthalate film is preferably, as an upper limit, 300 mN/25 mm or less, particularly preferably, 250 mN/25 mm or less, and more preferably, 200 mN/25 mm or less. When the upper limit of the adhesive strength is as described above, the peelability of the carrier sheet (1) from the flexible device becomes excellent. On the other hand, the adhesive strength is preferably, as a lower limit, 50 mN/25 mm or more, particularly preferably, 75 mN/25 mm or more, and more preferably, 100 mN/25 mm or more. When the lower limit of the adhesive strength is as described above, the carrier sheet (1) attached to the flexible device is suppressed from being unintentionally peeled off during each process.

Here, the adhesive strength in this specification basically refers to the adhesive strength measured by the 180-degree peeling method according to JIS Z0237:2009, but the measurement sample is 25 mm wide and 100 mm long, the measurement sample is attached to an adherend, pressurized at 0.5 MPa and 50°C for 20 minutes, left for 24 hours under conditions of normal pressure, 23°C, and 50% RH, and then measured at a peeling speed of 2.0 m/min.

(4) Haze value

The haze value of the laminate (in this embodiment, the laminate of the substrate (2) and the adhesive layer (3)) other than the release sheet (4) in the carrier sheet (1) according to the present embodiment is preferably 8% or less, particularly preferably 5% or less, and more preferably 2% or less. Since the haze value is the above or less, it is also suitable for the luminescence inspection of a flexible OLED device. In the carrier sheet (1) according to the present embodiment, since each of the substrate (2), the adhesive layer (3), and the release sheet (4) has antistatic properties, the amount of antistatic agent used in the adhesive layer (3) can be reduced, and the haze value of the adhesive layer (3) can be suppressed low. Thereby, the low haze value as described above can be achieved. In addition, the lower limit of the haze value is not particularly limited, and it is particularly preferably 0%. Here, the haze value in this specification is a value measured in accordance with JIS K7136:2000.

4. Purpose

As described above, the carrier sheet (1) according to the present embodiment is mainly used to return a flexible device while protecting its surface during processes such as processing, laminating, and inspection of the flexible device.

In order to use the carrier sheet (1) according to the present embodiment, first, the release sheet (4) is peeled off from the adhesive layer (3), and the carrier sheet (1) (a laminate of the substrate (2) and the adhesive layer (3)) is attached to a flexible device as a transported object via the exposed adhesive layer (3). Thereafter, the flexible device is returned while the carrier sheet (1) is attached, and is submitted to processes such as processing, lamination, and inspection. During these processes, the flexible device is prevented from being scratched or the like on the surface because the carrier sheet (1) is attached. When the above-described process is completed and the carrier sheet (1) becomes unnecessary, the carrier sheet (1) is peeled off from the flexible device.

In the carrier sheet (1) according to the present embodiment, all of the substrate (2), the adhesive layer (3), and the release sheet (4) have antistatic properties. Specifically, the substrate (2) has a first antistatic layer (22), the adhesive layer (3) contains an antistatic agent, and the release sheet (4) has at least one of a second antistatic layer (42a) and a third antistatic layer (42b). As a result, the carrier sheet (1) exhibits excellent antistatic properties in each process. For example, during the extrusion process of the carrier sheet (1), when the release sheet (4) is peeled from the adhesive layer (3) and the carrier sheet (1) is attached to a flexible device, during the processes of processing, laminating, inspection, etc. of the flexible device, and when the carrier sheet (1) is peeled from the flexible device, static electricity is unlikely to be generated, so that dust or dirt in the air can be suppressed from adhering to the flexible device due to static electricity. In addition, in the carrier sheet (1) according to the present embodiment, since each of the substrate (2), the adhesive layer (3), and the release sheet (4) has antistatic properties, the amount of antistatic agent used in the adhesive layer (3) can be reduced. As a result, the haze value of the adhesive layer (3), and further, the haze value of the entire carrier sheet (1) can be suppressed low. Therefore, the luminescence inspection of a flexible OLED device or the like to which the carrier sheet (1) is attached can be performed satisfactorily.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Accordingly, each element disclosed in the embodiments above is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

For example, a layer other than the first antistatic layer (22) may be additionally formed on the base film (21). In addition, the release agent layer (43) of the release sheet (4) may be omitted, and a layer other than the antistatic layer (42a, 42b) and the release agent layer (43) may be additionally formed on the release sheet (4).

(Example)

Hereinafter, the present invention will be described more specifically by examples, etc., but the scope of the present invention is not limited to these examples, etc.

〔Example 1〕

1. Manufacturing of the substrate (Formation of anti-static layer)

A diluted solution (manufactured by Chukyo Yushi Co., Ltd., product name "S-495", solid content 8.2 mass%) prepared by diluting a water-soluble hydroxyl group-containing polyester resin and PEDOT doped with PSS with dimethyl sulfoxide and water was mixed with a melamine compound solution (manufactured by Chukyo Yushi Co., Ltd., product name "P-795", solid content 70.0 mass%) prepared by diluting a water-soluble methylol melamine and water and an aqueous leveling agent solution (manufactured by Chukyo Yushi Co., Ltd., product name "R-438", solid content 10.0 mass%) prepared by diluting the solution with a solid content of 0.6 mass%, thereby obtaining a coating solution of a composition for an antistatic layer.

A coating solution of the antistatic layer composition was applied to one side (the side opposite the adhesive layer side) of a polyethylene terephthalate (PET) film (manufactured by Mitsubishi Jushisha Co., Ltd., product name "PET125T-100", thickness: 125 μm, containing filler) as a substrate film using a knife coater, and then heat-treated at 130° C. for 60 seconds to form a first antistatic layer having a thickness of 50 nm, thereby obtaining a substrate composed of a first antistatic layer/substrate film.

2. Preparation of a coating solution for the adhesive composition

2-1. Process (1)

100 parts by mass of a mixture (a) of 68.04 parts by mass of 2-ethylhexyl acrylate, 30.46 parts by mass of butyl acrylate, 0.23 parts by mass of 4-hydroxybutyl acrylate, and 1.27 parts by mass of acrylic acid was prepared, 40 parts by mass thereof was aliquoted and copolymerized by a solution polymerization method, thereby preparing a first (meth)acrylic acid ester copolymer (A). When the molecular weight of this polymer (A) was measured using gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 180,000. In addition, the conversion ratio at this time (a value obtained by dividing the mass of the copolymer obtained by polymerizing the monomer by the total mass of the monomer used as a raw material) was 80%.

2-2. Process (2)

100 parts by mass of a mixed solution (b) of 65.25 parts by mass of 2-ethylhexyl acrylate, 12.99 parts by mass of butyl acrylate, 16.23 parts by mass of an acrylic acid ester containing an ethylene oxide chain having a methoxy terminal (average added mole number = 9 mol), 4.72 parts by mass of 4-hydroxybutyl acrylate, and 0.81 parts by mass of acrylic acid was prepared, and 60 parts by mass thereof was aliquoted and added to a solution containing the copolymer (A) obtained by the step (1), and copolymerized together with the monomer remaining during polymerization of the first (meth)acrylic acid ester copolymer (A). Thereafter, when a portion of the solution was measured using GPC, it was confirmed that there was almost no change in the peak top of the weight average molecular weight of 180,000 of the copolymer (A). In addition, by subtracting the result of the GPC measurement in step (1) from the result of the current GPC measurement, the production of a new copolymer (B) having a weight average molecular weight of 15,000 was confirmed. Here, the mixing ratio of the copolymer (A) and the copolymer (B) was a mass ratio of 32:68 since the conversion ratio in the step (1) was 80%.

2-3. Process (3)

An amount of 100 parts by mass (in terms of solid content) of the acrylic polymer solution obtained by the above process (2) was collected and diluted with methyl ethyl ketone to a solid content concentration of 20% by mass. Then, 3.5 parts by mass (in terms of solid content; the same shall apply hereinafter) of an isocyanurate-type trimer of 1,6-hexamethylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., product name "Coronate HX") as an isocyanate crosslinking agent (C), 2.0 parts by mass of N-octyl-4-methylpyridinium hexafluorophosphate and 1.0 part by mass of potassium bis(fluorosulfonyl)imide (manufactured by Mitsubishi Materials Electronics Co., Ltd., product name "K-FSI") as an antistatic agent (D), and 1.0 part by mass of tributyl acetyl citrate as a plasticizer were added, and stirring was sufficiently performed to obtain a coating liquid of an adhesive composition.

Here, the weight average molecular weight described above is the weight average molecular weight converted to standard polystyrene measured (GPC measurement) under the following conditions using gel permeation chromatography (GPC).

<Measurement Conditions>

·GPC measuring device: HLC-8020, manufactured by Toshosha

·GPC Column (passed in the following order): Dososhaje

TSK guard column HXL-H

TSK gel GMHXL(×2)

TSK gel G2000HXL

·Measurement solvent: Tetrahydrofuran

·Measurement temperature: 40℃

3. Manufacturing of peeling sheets

A second antistatic layer was formed on one side of a polyethylene terephthalate film (manufactured by Mitsubishi Jushisha Co., Ltd., product name “PET25T-100”, thickness: 25 μm) as a support, in the same manner as the first antistatic layer described above, and a third antistatic layer was formed on the other side, in the same manner as the first antistatic layer described above.

Meanwhile, a silicone-based release agent (manufactured by Shin-Etsu Chemical Co., Ltd.) and a curing catalyst (manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed, diluted with toluene, and used as a coating solution for a release agent layer. The obtained coating solution was uniformly coated on the second antistatic layer using a Meyer bar, and then dried at 100° C. for 30 seconds to form a release agent layer having a thickness of 0.1 μm. In this way, a release sheet having a configuration of release agent layer/second antistatic layer/support/third antistatic layer was obtained.

4. Manufacturing of carrier sheets

In the substrate obtained in the above process 1, a coating solution of the adhesive composition obtained in the above process 2 was applied using a knife coater to a side on which the first antistatic layer does not exist, and then heat-treated at 90° C. for 1 minute to form an adhesive layer having a thickness of 25 μm. Next, the release sheet obtained in the above process 3 was bonded to the adhesive layer such that the release agent layer of the release sheet is in contact with the adhesive layer, thereby obtaining a carrier sheet.

〔Examples 2 to 7, Comparative Example 1〕

A carrier sheet was manufactured in the same manner as in Example 1, except that the base film, the adhesive layer, and the release sheet were changed to those shown in Table 1. In addition, as the release sheet of Example 3, one having an antistatic layer only on the adhesive layer side was used. As the base film of Example 4, a polyethylene terephthalate film (manufactured by Doresha, product name "PET75U48", thickness: 75 μm, filler-free) was used. As the release sheet of Example 6, one without an antistatic layer on the adhesive layer side was used. As the base film of Example 7, a polyethylene terephthalate film (manufactured by Mitsubishi Jushisha, product name "T100F38", thickness: 38 μm, filler-containing) was used. As the adhesive composition of Comparative Example 1, one similar to the adhesive composition of Example 1 was used, except that it did not contain an antistatic agent.

〔Test Example 1〕 (Measurement of surface resistivity)

In accordance with JIS K6911, the surface resistivity of the substrate used in the examples and comparative examples, the adhesive surface of the adhesive layer exposed by peeling the release sheet from the carrier sheet, and the adhesive layer side of the release sheet and the opposite side (carrier sheet back side) was measured. Specifically, in an environment of 23°C and a relative humidity of 50%, a resistivity meter (manufactured by Mitsubishi Analytex, product name "Hiresta UP MCP-HT450 type") was used to measure the surface resistivity (Ω/sq) of each surface after applying a voltage of 100 V for 10 seconds to the substrate, the carrier sheet from which the release sheet was peeled (substrate + adhesive layer), or the release sheet (100 mm × 100 mm). The results are shown in Table 1. In addition, the surface resistivity of the back surface of the carrier sheet of the release sheet used in Example 3, the surface resistivity of the adhesive layer side of the release sheet used in Example 6, and the surface resistivity of the adhesive surface of the adhesive layer in the carrier sheet of Comparative Example 1 were all values exceeding the measurement limit.

〔Test Example 2〕 (Measurement of Haze Value)

The haze value (%) of the substrates used in the examples and comparative examples was measured using a haze meter (product name "NDH7000" manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS K7136:2000. The results are shown in Table 1. In addition, the haze value (%) of the laminate obtained by peeling off the release sheet from the carrier sheet manufactured in the examples and comparative examples was measured in the same manner. The results are shown in Table 2.

〔Test Example 3〕 (Peeling voltage)

The carrier sheets manufactured in the examples and comparative examples were cut to 25 mm x 100 mm, and these were used as samples. In an environment of 23°C and a relative humidity of 50%, the peeling sheet was manually peeled from the sample at a peeling speed of 2.0 m/min, and 5 seconds after peeling, an electrostatic meter (manufactured by Shimuko Japan, product name "FMX-003") was used to measure the electrostatic potential (peeling voltage; V) at a position 2.0 cm from the exposed surface (adhesive surface) of the adhesive layer and the electrostatic potential (peeling voltage; V) at a position 2.0 cm from the exposed surface on the adhesive layer side of the peeling sheet. The results are shown in Table 2.

〔Test Example 4〕(Measurement of adhesive strength)

In the examples and comparative examples, the release sheet was peeled off from the carrier sheet manufactured, and the exposed adhesive layer was attached to soda lime glass (manufactured by Central Glass Co., Ltd.), and then pressurized at 0.5 MPa and 50°C for 20 minutes in an autoclave manufactured by Kurihara Seisakujo Co., Ltd. Thereafter, the sheet was left to stand for 24 hours under conditions of 23°C and 50% RH, and then the adhesive strength (mN/25 mm) was measured using a tensile tester (manufactured by Orientex, Tensilon) under the conditions of a peel speed of 2.0 m/min and a peel angle of 180 degrees. The measurement was performed in accordance with JIS Z 0237:2009 for conditions other than those described herein. The results are shown in Table 2.

In addition, the adhesive strength (mN/25mm) was measured in the same manner as above, except that the adherend was changed to a polyethylene terephthalate (PET) film (Doresha, product name "Lumira 50T60", thickness 50㎛, fixed to a glass plate). The results are shown in Table 2.

〔Example 5〕 (Stamp Test)

The carrier sheets manufactured in the examples and comparative examples were placed on a hard flat plate with the substrate side facing upward. Then, using a durometer (manufactured by Gobun Shigekisha, product name "Asuka Rubber Durometer C2 Type", the shape of the pressing core was a hemispherical shape with a diameter of 2.54 mm), a point load of 400 g was applied to the substrate surface of the carrier sheet for 10 seconds to create a dent. One minute later, the dent depth was measured using an optical interference microscope (manufactured by Veeco, product name "Surface Shape Measuring Device WYKO NT110"). At this time, the measurement conditions were VSI, magnification 2.5 times, and measurement range 2.5 mm × 1.9 mm. In addition, the images and graphs acquired in the measurement are shown in Fig. 2 for reference. Based on the measurement results, the dent resistance was evaluated according to the following evaluation criteria. The results are shown in Table 2.

◎: Depth of the mark is less than 0.5㎛

○: The depth of the mark is 0.5㎛ or more and less than 1.0㎛.

×: The depth of the mark is 1.0㎛ or more

〔Test Example 6〕 (Foreign Material Insertion Test)

A very small amount of silicone resin filler (Momentive Shark, product name "Tospal 145L", average particle size: 4.5 μm) was dispersed and monodispersed on a 7 cm x 7 cm soda-lime glass plate. The release sheet was peeled from the carrier sheet manufactured in the examples and comparative examples, and the exposed adhesive layer was attached to the soda-lime glass plate. Next, it was subjected to autoclave treatment for 20 minutes under the conditions of 50°C and 0.5 MPa, and then left at normal pressure, 23°C, and 50% RH for 24 hours, and this was used as a sample.

For the obtained sample, whether the filler was embedded in the adhesive layer (whether there was air inflow due to the filler) was visually observed from the carrier sheet side, and the foreign matter embedding property was evaluated according to the following criteria. The results are shown in Table 2.

○: The filler is sufficiently embedded in the adhesive layer.

△: Partial air inflow occurs

×: Air inflow occurs overall

[Table 1]

[Table 2]

As is clear from Table 2, the carrier sheets manufactured in the examples have excellent peeling charge prevention properties at least on the adhesive surface of the adhesive layer, and the haze value is suppressed to a low level. In addition, the carrier sheets manufactured in Examples 1 to 3, 5, and 6 also have excellent scratch resistance. In addition, the carrier sheets manufactured in Examples 1, 3, 4, and 6 also have excellent foreign matter embedding properties.

The carrier sheet for a flexible device according to the present invention is particularly suitable as a carrier sheet used in processes such as processing, laminating, and inspecting a flexible OLED device.

1: Carrier sheet for flexible devices
2 : Description
21: Base film
22: 1st anti-static layer
3: Adhesive layer
4: Peeling sheet
41 : Support
42a: Second anti-static layer
42b: Third anti-static layer
43: Peeling layer

Claims (8)

As a carrier sheet for a flexible device for protecting and returning a flexible device,
With description,
An adhesive layer laminated on one side of the above description,
A peeling sheet laminated on the surface opposite to the substrate in the above adhesive layer
It is equipped with,
All of the above-mentioned description, the adhesive layer and the peeling sheet have antistatic properties,
The above adhesive layer contains a pyridinium hexafluorophosphate compound and a fluorosulfonylimide compound as an antistatic agent.
A carrier sheet for a flexible device, characterized by: In the first paragraph,
The above-mentioned substrate has a substrate film and an antistatic layer formed on one surface of the substrate film,
The above adhesive layer is laminated on the substrate so as to be located on the other side of the substrate film.
A carrier sheet for a flexible device, characterized by: In the first paragraph,
A carrier sheet for a flexible device, characterized in that the above-mentioned peeling sheet has a support and an antistatic layer formed on at least one surface side of the support. In the first paragraph,
A carrier sheet for a flexible device, characterized in that when a voltage of 100 V is applied for 10 seconds to the carrier sheet for a flexible device formed by peeling the peeling sheet in an environment of 23°C and a relative humidity of 50%, the surface resistivity of the exposed surface of the adhesive layer is 1×10 ⁷ Ω/sq or more and 1×10 ¹¹ Ω/sq or less. In the first paragraph,
A carrier sheet for a flexible device, characterized in that when a voltage of 100 V is applied to the substrate for 10 seconds in an environment of 23°C and a relative humidity of 50%, the surface resistivity of a surface of the substrate opposite to the adhesive layer is 1×10 ⁷ Ω/sq or more and 1×10 ¹¹ Ω/sq or less. In the first paragraph,
A carrier sheet for a flexible device, characterized in that when a voltage of 100 V is applied to the peeling sheet for 10 seconds in an environment of 23°C and a relative humidity of 50%, the surface resistivity of the surface on the adhesive layer side of the peeling sheet is 1×10 ⁷ Ω/sq or more and 1×10 ¹¹ Ω/sq or less. In the first paragraph,
A carrier sheet for a flexible device, characterized in that when a voltage of 100 V is applied to the peeling sheet for 10 seconds in an environment of 23°C and a relative humidity of 50%, the surface resistivity of a surface of the peeling sheet opposite to the adhesive layer is 1×10 ⁷ Ω/sq or more and 1×10 ¹¹ Ω/sq or less. In any one of claims 1 to 7,
A carrier sheet for a flexible device, characterized in that the haze value of the carrier sheet for a flexible device, excluding the above-mentioned peeling sheet, is 8% or less.