CN110643323A

CN110643323A - Adhesive sheet

Info

Publication number: CN110643323A
Application number: CN201910475550.1A
Authority: CN
Inventors: 渡边旭平; 荒井隆行
Original assignee: Lindeko Corp
Current assignee: Lindeko Corp; Lintec Corp
Priority date: 2018-06-26
Filing date: 2019-06-03
Publication date: 2020-01-03
Also published as: JP2020002203A; JP6676706B2

Abstract

The invention provides an adhesive sheet which has good removability and excellent adhesion between a base material and an adhesive layer even if the adhesive layer contains a specified functional additive. The adhesive sheet (1) is provided with a substrate (11) and an adhesive layer (12) laminated on one surface of the substrate (11), wherein the adhesive layer (12) is formed by an organic silicon adhesive composition containing an organic silicon adhesive, a functional additive and a silane coupling agent, the organic silicon adhesive contains an addition reaction type organic silicon resin and a platinum catalyst, the addition reaction type organic silicon resin is obtained by a first polydimethylsiloxane having at least two alkenyl groups in one molecule and a second polydimethylsiloxane having at least two hydrosilyl groups in one molecule, and the functional additive is composed of an organic material.

Description

Adhesive sheet

Technical Field

The present invention relates to an adhesive sheet that can be suitably used as a protective sheet for protecting devices, an adhesive sheet for decoration, a coloring sheet for protecting a graphite sheet, and the like.

Background

Conventionally, in devices such as optical members and electronic members, an adhesive sheet including a base material and an adhesive layer is sometimes stuck as a protective sheet on the surface of the device in order to prevent damage to the surface in the steps of processing, assembly, inspection, and the like. The protective sheet is peeled off the device when protection is not required.

In recent years, as an optical member, a movement to shift from a liquid crystal device to an Organic Light Emitting Diode (OLED) device has been active. Further, studies on OLED devices having flexibility (hereinafter, sometimes referred to as "flexible OLED devices") have also been actively conducted. Since the flexible OLED device is flexible unlike a liquid crystal device and a general OLED device, when a conventional protective sheet is used, the flexible OLED device is difficult to be peeled off. In addition, in the inspection process of the OLED device, the protective sheet is sometimes exposed to high temperature conditions, and therefore, the protective sheet is required to have heat resistance. In this context, a silicone-based adhesive is preferable as the adhesive for forming the adhesive layer.

As an example of the silicone adhesive, patent document 1 discloses a room temperature-curable silicone adhesive which is cured by reaction with moisture in the air. In particular, the examples of patent document 1 disclose the following: a sheet made of a silicone adhesive is formed by injecting a composition containing a predetermined polyorganosiloxane and a partial hydrolysate of an organosilicon compound into a mold, and aging the composition at 23 ℃ and 50% RH for seven days.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2007-321122

Disclosure of Invention

Technical problem to be solved by the invention

The silicone adhesive disclosed in patent document 1 is an adhesive that is supposed to be used for sealing, adhesion, and coating, and does not exhibit sufficient removability to an adherend. Therefore, an adhesive sheet provided with an adhesive layer made of the silicone adhesive is not suitable for applications requiring removability such as a protective sheet of a device.

In addition, in a protective sheet of a device, a functional additive such as an antistatic agent may be added to an adhesive agent constituting an adhesive agent layer to impart a desired function to the protective sheet. The inventors of the present application confirmed that: in particular, when a substance composed of an organic material is used as such a functional additive, adhesion between the base material and the adhesive agent layer is reduced, and interlayer peeling is likely to occur between the base material and the adhesive agent layer. In particular, when the adhesive forming the adhesive layer is the conventional silicone adhesive as described above, the above-described decrease in adhesion is significant, and interlayer peeling is very likely to occur.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive sheet having good removability and excellent adhesion between a base material and an adhesive layer even when the adhesive layer contains a predetermined functional additive.

Means for solving the problems

In order to achieve the above object, the present invention provides an adhesive sheet comprising a substrate and an adhesive layer laminated on one surface of the substrate, wherein the adhesive layer is formed from a silicone adhesive composition comprising a silicone adhesive, a functional additive and a silane coupling agent, the silicone adhesive comprises an addition reaction type silicone resin and a platinum catalyst, the addition reaction type silicone resin is obtained from a first polydimethylsiloxane having at least two alkenyl groups in one molecule and a second polydimethylsiloxane having at least two hydrosilyl groups in one molecule, and the functional additive is formed from an organic material (invention 1).

The adhesive sheet of the invention (invention 1) can achieve good removability by forming the adhesive layer with the silicone adhesive containing the addition reaction type silicone resin as described above. In addition, in the adhesive sheet, the adhesive layer is composed of the silicone adhesive composition containing the silane coupling agent, so that even if the adhesive layer contains the specified functional additive, the base material and the adhesive layer show excellent adhesion.

In the above invention (invention 1), the functional additive is preferably at least one of an ultraviolet absorber, a colorant, an antistatic agent and light diffusing fine particles (invention 2).

In the above inventions (inventions 1 and 2), the content of the silane coupling agent is preferably 0.001 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the addition reaction type silicone resin (invention 3).

In the above inventions (inventions 1 to 3), the silicone adhesive preferably contains a silicone resin (invention 4).

In the above inventions (inventions 1 to 4), the content of the silicone resin is preferably 1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the addition reaction type silicone resin (invention 5).

In the above inventions (inventions 1 to 5), it is preferable that an easy adhesion layer is provided on a surface of the base material on the side where the adhesive agent layer is laminated (invention 6).

In the above inventions (inventions 1 to 6), the pressure-sensitive adhesive sheet is preferably used as a protective sheet for protecting a device (invention 7).

In the above invention (invention 7), it is preferable that the device is a flexible device (invention 8).

Effects of the invention

The adhesive sheet of the present invention has good removability and also has excellent adhesion between the base material and the adhesive layer even when the adhesive layer contains a predetermined functional additive.

Drawings

Fig. 1 is a sectional view of an adhesive sheet according to an embodiment of the present invention.

Description of the reference numerals

1: an adhesive sheet; 11: a substrate; 12: an adhesive layer; 13: and (4) peeling off the sheet.

Detailed Description

Hereinafter, embodiments of the present invention will be described.

[ adhesive sheet ]

As shown in fig. 1, the adhesive sheet 1 of the present embodiment is composed of a substrate 11, an adhesive layer 12 laminated on one surface (lower side in fig. 1) of the substrate 11, and a release sheet 13 laminated on the surface (lower side in fig. 1) of the adhesive layer 12 opposite to the substrate 11. The release sheet 13 protects the adhesive layer 12 until the adhesive sheet 1 is used, and is peeled off and removed when the adhesive sheet 1 is used. The release sheet 13 may be omitted from the adhesive sheet 1 of the present embodiment.

1. Each component

(1) Base material

The substrate 11 is not particularly limited as long as the adhesive layer 12 can be laminated, and a substrate corresponding to the application of the adhesive sheet 1 of the present embodiment is preferably used. For example, when the adhesive sheet 1 of the present embodiment is used as a protective sheet of a device, the substrate 11 preferably has transparency to light of a wavelength used for light emission inspection of the device. The substrate 11 preferably has heat resistance to a high temperature (for example, 90 to 150 ℃) applied in inspection of a device to be protected.

Specific examples of the substrate 11 include plastic films made of polyesters such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, celluloses such as cellulose diacetate, cellulose triacetate, and cellulose acetate butyrate (acetyl cellulose butyrate), polyolefins such as polyethylene and polypropylene, and resins such as polyimide, polyetherimide, polycarbonate, polymethylpentene, polyphenylene sulfide, and liquid crystal polymers. The plastic film may be a single-layer film or a film obtained by laminating a plurality of layers of the same type or different types. Among the above, a polyester film or a cellulose film is preferable from the viewpoint of transparency and cost, and a polyester film is more preferable from the viewpoint of heat resistance, and a polyethylene terephthalate film is particularly preferable.

The plastic film may contain additives such as an antistatic agent, a heat resistance improver, and an ultraviolet absorber, but when high transparency is required, it is preferable not to contain a filler.

The substrate 11 of the present embodiment may have a desired functional layer on one surface or both surfaces thereof. Examples of the functional layer include a hard coat layer, an antireflection layer, an antiglare layer, an easy slip layer, and a color correction layer. The base material 11 of the present embodiment may have an antistatic layer as the functional layer, or may not have an antistatic layer. In particular, when the adhesive layer 12 of the present embodiment contains an antistatic agent as a functional additive, the substrate 11 may not have an antistatic layer because desired antistatic properties can be achieved by the adhesive layer 12.

The substrate 11 is preferably provided with an easy adhesion layer at least on the surface on which the adhesive layer 12 is laminated, for the purpose of improving adhesion to the adhesive layer 12. The material of the easy adhesion layer is not particularly limited, and examples thereof include polyester resins, urethane resins, polyester urethane resins, and acrylic resins. Among them, the material of the easy adhesion layer is preferably a material at least a part of which is dissolved in a solvent used in the coating liquid of the adhesive composition. This is because, when the adhesive layer is formed on the easy adhesion layer made of such a material, it is presumed that a mixed layer made of a material derived from both layers is formed on the interface between the easy adhesion layer and the adhesive layer, and the adhesion between the base material and the adhesive layer is further improved. The thickness of the easy adhesion layer is usually 0.005 μm or more, preferably 0.01 μm or more. The thickness is usually 10 μm or less, preferably 5 μm or less.

In addition, the surface treatment or the undercoating treatment by an oxidation method, an embossing method, or the like may be performed on at least the surface on which the adhesive layer 12 is laminated, for the purpose of improving the adhesion to the adhesive layer 12, of the substrate 11. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromate treatment (wet treatment), flame treatment, hot air treatment, ozone treatment, and ultraviolet irradiation treatment, and examples of the roughening method include sand blast treatment and thermal spray treatment. These surface treatment methods may be appropriately selected depending on the kind of the substrate 11.

The total light transmittance of the substrate 11 of the present embodiment is preferably 80% or more, particularly preferably 85% or more, and further preferably 88% or more. When the total light transmittance is 80% or more, the transparency of the pressure-sensitive adhesive sheet 1 of the present embodiment becomes higher. The upper limit of the total light transmittance is not particularly limited, and is preferably 100% or less, particularly preferably 98% or less, and further preferably 93% or less. The total light transmittance of the substrate 11 was measured in accordance with JIS K7361-1:1997 and ASTM D1003, and the detailed measurement method thereof is shown in the following description of test examples.

The haze value of the substrate 11 of the present embodiment is preferably 3.5% or less, more preferably 2.5% or less, particularly preferably 2.0% or less, and further preferably 1.3% or less. When the haze value is 3.5% or less, the transparency of the pressure-sensitive adhesive sheet 1 of the present embodiment becomes higher. The lower limit of the haze value is not particularly limited, but is preferably 0.1% or more, particularly preferably 0.2% or more, and further preferably 0.3% or more. The haze value of the substrate 11 was measured in accordance with JIS K7136:2000 and ASTM D1003, and the detailed measurement method thereof is shown in the following description of test examples.

The thickness of the substrate 11 is preferably 10 μm or more, particularly preferably 25 μm or more, and more preferably 38 μm or more. The thickness of the substrate 11 is preferably 200 μm or less, more preferably 175 μm or less, particularly preferably 150 μm or less, and further preferably 80 μm or less. When the thickness of the substrate 11 is set to the above range, the adhesive sheet 1 of the present embodiment is more excellent in transparency, heat resistance, and workability of attachment and detachment.

(2) Adhesive layer

The adhesive layer 12 is formed of a silicone adhesive composition containing a silicone adhesive containing an addition reaction type silicone resin obtained from a first polydimethylsiloxane having at least two alkenyl groups in one molecule and a second polydimethylsiloxane having at least two hydrosilyl groups in one molecule, a functional additive composed of an organic material, and a silane coupling agent, and a platinum catalyst.

In the adhesive sheet 1 of the present embodiment, the adhesive layer 12 is formed of the silicone adhesive containing the addition reaction type silicone resin as described above, whereby good removability from an adherend can be achieved. Further, when the adhesive layer 12 is formed of a silicone-based adhesive composition containing a functional additive, the adhesive sheet 1 of the present embodiment can exhibit a desired function corresponding to the functional additive.

Here, in a general adhesive sheet, when the adhesive layer contains a functional additive composed of an organic material, the adhesion between the base material and the adhesive layer is reduced, and the inventors of the present application have confirmed that: delamination is likely to occur at the interface between the substrate and the adhesive layer. On the other hand, when the adhesive agent layer does not contain a functional additive or contains a functional additive composed of an inorganic material, the adhesion between the base material and the adhesive agent layer is less likely to decrease, and the above-described problem of interlayer peeling is also less likely to occur.

As described above, when a functional additive made of an organic material is used in a general adhesive sheet, the following reason is considered as one reason for the decrease in adhesion between the adhesive layer and the base material. It is presumed that, when the adhesive layer is formed, the functional additive composed of an organic material is likely to segregate at a position near the interface with the substrate in the adhesive layer due to, for example, a difference in polarity between the silicone adhesive and the functional additive. It is also considered that the functional additive that segregates reduces the substantial contact area between the silicone adhesive and the substrate, and as a result, the adhesion of the adhesive layer to the substrate is reduced.

However, in the adhesive sheet 1 of the present embodiment, the silicone adhesive composition for forming the adhesive layer 12 contains a silane coupling agent in addition to a functional additive composed of an organic material. Thus, in the adhesive agent layer 12 formed, the above-described segregation of the functional additive is less likely to occur, and the adhesion between the substrate 11 and the adhesive agent layer 12 is favorably ensured. As a result, interlayer peeling at the interface between the substrate 11 and the adhesive layer 12 is less likely to occur. In particular, even after the adhesive sheet 1 of the present embodiment is left under a durable condition such as exposure to an environment having a temperature of 85 ℃ and a relative humidity of 85% for seven days, the occurrence of the above-described interlayer peeling can be favorably suppressed.

(2-1) Silicone adhesive

The silicone adhesive is not particularly limited as long as it contains the addition reaction type silicone resin and the platinum catalyst and enables the adhesive sheet 1 of the present embodiment to be attached to and detached from an adherend. When the pressure-sensitive adhesive sheet 1 of the present embodiment is used as a protective sheet for protecting an adherend exposed to high temperatures (e.g., 90 to 150 ℃) during inspection or use, the silicone pressure-sensitive adhesive is preferably a pressure-sensitive adhesive that exhibits stable pressure-sensitive adhesion even at such high temperatures. In particular, when the adherend is a flexible device such as a flexible OLED device, a micro-adhesive silicone adhesive having excellent re-peelability is preferably selected in order to easily peel the adhesive sheet 1 of the present embodiment from the flexible device. In addition, silicone adhesives exhibit stable adhesion even at high temperatures and are superior in heat resistance compared to acrylic adhesives.

The addition reaction type silicone resin of the present embodiment is obtained from a first polydimethylsiloxane having at least two alkenyl groups in one molecule and a second polydimethylsiloxane having at least two hydrosilyl groups in one molecule.

Examples of the alkenyl group contained in the first polydimethylsiloxane include monovalent hydrocarbon groups such as a vinyl group, an allyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, and an octenyl group, and among them, a vinyl group is particularly preferable.

The content of alkenyl groups in the first polydimethylsiloxane (the ratio of the number of alkenyl groups to the number of methyl groups bonded to silicon atoms) is preferably 0.005 mol% or more, and particularly preferably 0.01 mol% or more. The content is preferably 0.1 mol% or less, and particularly preferably 0.05 mol% or less. The first polydimethylsiloxane preferably has alkenyl groups at both ends of the molecular chain, and may have alkenyl groups in side chains. By making the first polydimethylsiloxane to contain at least two alkenyl groups in one molecule and making the content of the alkenyl groups within the above range, a crosslinked structure with high crosslink density can be formed, and an adhesive layer with excellent removability can be obtained.

The degree of polymerization (number of siloxane bonds) of the first polydimethylsiloxane is preferably 200 or more, and particularly preferably 500 or more. The polymerization degree is preferably 5,000 or less, and particularly preferably 3,000 or less.

The content of hydrosilyl groups in the second polydimethylsiloxane is preferably 2 or more, and particularly preferably 4 or more in one molecule. The content is preferably 300 or less, and particularly preferably 200 or less in one molecule.

The polymerization degree of the second polydimethylsiloxane is preferably 50 or more, and particularly preferably 100 or more. The polymerization degree is preferably 2,000 or less, and particularly preferably 1,500 or less.

Further, the blending ratio of the second polydimethylsiloxane to 100 parts by mass of the first polydimethylsiloxane is preferably 0.01 part by mass or more, and particularly preferably 0.1 part by mass or more. The blending ratio is preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less.

As described above, when the content of each functional group and the blending ratio of the second polydimethylsiloxane to the first polydimethylsiloxane are in the above ranges, an addition reaction type silicone resin in which an addition reaction of the first polydimethylsiloxane and the second polydimethylsiloxane is favorably caused can be easily obtained.

In addition, the first polydimethylsiloxane preferably has no hydrosilyl group, and the second polydimethylsiloxane preferably has no alkenyl group.

The weight average molecular weight of the first polydimethylsiloxane is preferably 2 ten thousand or more, and particularly preferably 30 ten thousand or more. The weight average molecular weight is preferably 130 ten thousand or less, and particularly preferably 120 ten thousand or less. The weight average molecular weight of the second polydimethylsiloxane is preferably 300 or more, and particularly preferably 500 or more. The weight average molecular weight is preferably 1400 or less, and particularly preferably 1200 or less. The weight average molecular weight in the present specification is a value in terms of standard polystyrene measured by a Gel Permeation Chromatography (GPC) method.

The platinum catalyst is not particularly limited as long as it can cure the addition reaction type silicone resin (addition reaction of the first polydimethylsiloxane and the second polydimethylsiloxane). Preferred examples of the platinum catalyst include platinum group metal compounds such as particulate platinum, particulate platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, rhodium, and palladium.

The amount of the catalyst to be added to 100 parts by mass of the addition reaction type silicone resin is preferably 0.01 part by mass or more, and particularly preferably 0.05 part by mass or more, in terms of the platinum component. The amount of the platinum component is preferably 3 parts by mass or less, and particularly preferably 2 parts by mass or less.

Preferably, the silicone adhesive further contains a silicone resin. By containing a silicone resin in the silicone adhesive, the obtained adhesive layer 12 is more excellent in substrate adhesion. This makes it possible to exhibit excellent adhesion to a highly smooth substrate. As the silicone resin, for example, it is preferable to use an MQ resin composed of an M unit which is a monofunctional siloxane unit [ (CH)₃)₃SiO_1/2]The Q unit is a tetrafunctional siloxane unit [ SiO ]_4/2]. In this case, the molar ratio of the M unit/Q unit is preferably 0.6 to 1.7.

When the silicone adhesive contains a silicone resin, the amount of the silicone resin to be blended is preferably 1 part by mass or more, particularly preferably 3 parts by mass or more, and more preferably 5 parts by mass or more, per 100 parts by mass of the addition reaction type silicone resin. The amount of the above-mentioned additive is preferably 40 parts by mass or less, particularly preferably 30 parts by mass or less, and further preferably 20 parts by mass or less. When the amount of the silicone resin blended is within the above range, the substrate adhesion and the removability as an adhesive sheet can be achieved at a higher level.

(2-2) functional additive

The functional additive according to the present embodiment is not particularly limited as long as it is made of an organic material and imparts a desired function to the adhesive sheet 1. Examples of the functional additive in the present embodiment include an ultraviolet absorber, a colorant, an antistatic agent, light diffusing fine particles, an antioxidant, and the like. These functional additives may be used singly or in combination of two or more as long as the adhesive sheet 1 can exhibit the desired function.

In addition, the organic material in the present specification means: a material composed only of an organic compound, and a material containing an organic compound as at least one constituent element. Therefore, the functional additive composed of an organic material in the present embodiment does not contain a material composed of only an inorganic compound, and particularly does not contain an inorganic filler. In addition, although carbon black, which is one of the colorants, is sometimes classified as an inorganic compound, carbon black generally has a structure of an organic compound in a part thereof or is considered to be in a form accompanied by a dispersion of an organic compound, and therefore, in the present specification, carbon black corresponds to an organic material.

Examples of the ultraviolet absorber include compounds such as benzophenones, benzotriazoles, benzoates, benzoxazinones, triazines, benzoates, cyanoacrylates, and nickel complex salts, and among them, at least one of benzophenone compounds, benzotriazole compounds, and triazine compounds is preferably used.

Examples of the benzophenone-based compound include 2, 2-dihydroxy-4-methoxybenzophenone, 2, 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid hydrate, and 2-hydroxy-4-n-octoxybenzophenone, and among these, 2-dihydroxy-4-methoxybenzophenone is preferably used.

Examples of the benzotriazole-based compound include 2- (2-hydroxy-5-t-butylphenyl) -2H-benzotriazole, octyl-3- [ 3-t-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl ] propionate, and 2-ethylhexyl-3- [ 3-t-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl ] propionate.

Examples of the triazine compound include 2, 4-bis [ 2-hydroxy-4-butoxyphenyl ] -6- (2, 4-dibutoxyphenyl) -1,3, 5-triazine, and 2- [4, 6-bis (2, 4-xylyl) -1,3, 5-triazin-2-yl ] -5-octyloxyphenol.

The ultraviolet absorber may be used alone or in combination of two or more.

When an ultraviolet absorber is used as the functional additive in the present embodiment, the content of the ultraviolet absorber in the silicone adhesive composition is preferably 0.1 part by mass or more, particularly preferably 0.5 part by mass or more, and more preferably 1.0 part by mass or more, per 100 parts by mass of the addition-reaction type silicone resin. The content is preferably 15 parts by mass or less, particularly preferably 12 parts by mass or less, and further preferably 10 parts by mass or less, per 100 parts by mass of the addition-reaction type silicone resin. When the content of the ultraviolet absorber is in the above range, the adhesive layer 12 can easily exhibit good ultraviolet absorbability.

Examples of the colorant include organic pigments, organic dyes, and the like, in addition to the carbon black. Carbon black in the form of a dispersion is preferably used, and examples of a dispersion medium for forming such a dispersion include styrene-maleic acid resin, urethane resin, epoxy resin, polyester urethane resin, and the like. Among them, as the dispersion medium, a styrene-maleic acid resin is preferably used.

Further, specific examples of the organic pigment and the organic dye include amines

(aminium) pigments, cyanine pigments, merocyanine pigments, croconic acid (croconium) pigments, squarylium (squarylium) pigments, azulenium (azulenium) pigments, polymethine pigments, naphthoquinone pigments, pyrylium pigments, phthalocyanine pigmentsNaphthalocyanine pigments, naphthoylimide (naphtholactam) pigments, azo pigments, condensed azo pigments, indigo pigments, perinone pigments, perylene pigments, dioxazine pigments, quinacridone pigments, isoindolinone pigments, quinophthalone pigments, pyrrole pigments, thioindigo pigments, metal complex pigments (metal complex dyes), dithiol metal complex pigments, indophenol pigments, triarylmethane pigments, anthraquinone pigments, dioxazine pigments, phenol naphtho pigments, azomethine pigments, benzimidazolone pigments, pyranthrone pigments, and threne (threne) pigments.

The above-mentioned coloring agent is appropriately selected and used according to the color to be colored. In particular, when it is desired to color the adhesive layer 12 black, carbon black, a mixture of the above-described pigments, or the like is preferably used, and among these, carbon black is preferably used, and a styrene-maleic acid resin dispersion of carbon black is particularly preferably used. When it is desired to color the adhesive agent layer 12 blue, it is preferable to use a phthalocyanine-based pigment, an anthraquinone-based pigment, or the like, and among these, a phthalocyanine-based pigment is preferably used, and copper phthalocyanine blue is particularly preferably used.

The above colorants may be used singly or in combination of two or more.

In the case of using a colorant as the functional additive in the present embodiment, the content of the colorant in the silicone adhesive composition is usually set as appropriate depending on the kind of the colorant, but is preferably 0.1 part by mass or more, particularly preferably 0.3 part by mass or more, and further preferably 0.5 part by mass or more, for example, relative to 100 parts by mass of the addition reaction type silicone resin. The content is preferably 10 parts by mass or less, particularly preferably 9 parts by mass or less, and further preferably 8 parts by mass or less, per 100 parts by mass of the addition-reaction type silicone resin. When the content of the colorant is in the above range, the adhesive layer 12 can easily exhibit a desired color.

Examples of the antistatic agent for the colorant include an ionic compound, a nonionic compound, a conductive polymer, a surfactant, conductive fine particles, and the like, and among them, an ionic compound is preferable.

Examples of the ionic compound include nitrogen-containing onium salts, sulfur-containing onium salts, phosphorus-containing onium salts, alkali metal salts, and alkaline earth metal salts, and among them, alkali metal salts are preferable. Examples of the cation of the alkali metal salt include potassium ion, lithium ion, and sodium ion, and among them, potassium ion is preferable.

On the other hand, examples of the anion constituting the ionic compound include sulfonyl imide anions, halogenated phosphate anions, and the like. Examples of the sulfonyl imide anion include bis (fluoroalkylsulfonyl) imide and bis (fluorosulfonyl) imide, and among these, bis (fluorosulfonyl) imide is preferable. Examples of the halogenated phosphate anion include hexafluorophosphate and the like.

More specific examples of the antistatic agent include 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, N-hexadecyl-4-methylpyridinium hexafluorophosphate, N-decyl pyridinium bis (fluorosulfonyl) imide, N-acetyl-4-methylpyridinium hexafluorophosphate, N-dodecyl-4-methylpyridinium hexafluorophosphate, 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, lithium bis (fluoromethanesulfonyl) imide, and the like. Among them, potassium bis (fluorosulfonyl) imide is preferable.

The antistatic agents may be used singly or in combination of two or more.

When an antistatic agent is used as the functional additive in the present embodiment, the content of the antistatic agent in the silicone adhesive composition is preferably 0.1 part by mass or more, particularly preferably 0.5 part by mass or more, and more preferably 1.0 part by mass or more, per 100 parts by mass of the addition-reaction type silicone resin. 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, per 100 parts by mass of the addition-reaction type silicone resin. When the content of the antistatic agent is in the above range, the adhesive agent layer 12 can easily exhibit good antistatic properties.

Examples of the light diffusing fine particles include transparent or white fine particles made of a resin such as an acrylic resin, a polystyrene resin, a polyethylene resin, an epoxy resin, or a silicone resin, and fine particles made of a silicon-containing compound having an intermediate structure between inorganic and organic. Among them, acrylic resin fine particles are preferably used.

Examples of the acrylic resin fine particles include resin fine particles composed of a homopolymer of methyl methacrylate, and resin fine particles composed of a copolymer of methyl methacrylate and a monomer such as vinyl acetate, styrene, methyl acrylate, or ethyl (meth) acrylate. The acrylic resin fine particles preferably have a crosslinked structure. In view of the ease of achieving uniform light diffusion, the light-diffusing fine particles of the present embodiment are preferably fine particles made of crosslinked polymethyl methacrylate.

The shape of the light diffusing fine particles may be a regular shape such as a sphere or an irregular shape whose shape is not specified, but is preferably a sphere, particularly preferably a regular sphere, from the viewpoint of easily achieving uniform light diffusion.

The light diffusing particles may be used alone or in combination of two or more.

When light-diffusing fine particles are used as the functional additive in the present embodiment, the content of the light-diffusing fine particles in the silicone adhesive composition is preferably 1.0 part by mass or more, particularly preferably 2.0 parts by mass or more, and more preferably 3.0 parts by mass or more, per 100 parts by mass of the addition-reaction type silicone resin. The content is preferably 15 parts by mass or less, particularly preferably 12 parts by mass or less, and further preferably 10 parts by mass or less, per 100 parts by mass of the addition-reaction type silicone resin. When the content of the light diffusing fine particles is in the above range, the adhesive layer 12 can easily exhibit good light diffusing properties.

(2-3) silane coupling agent

The silane coupling agent is preferably an organosilicon compound having at least one alkoxy group bonded to a silicon atom in the molecule and at the same time having at least one functional group reactive with an organic compound.

Examples of the functional group reactive with the organic compound include at least one selected from glycidyl groups, amino groups, vinyl groups, isocyanate groups, mercapto groups, (meth) acryloyl groups, styryl groups, and ureido groups. Among them, the silane coupling agent preferably has at least one of a glycidyl group and an amino group, and particularly preferably has an amino group, from the viewpoint of easily achieving excellent adhesion between the adhesive layer 12 and the substrate 11. From the viewpoint of improving the reactivity of the functional group and improving the compatibility with other components in the silicone adhesive composition, it is preferable that a spacer (spacer) represented by the general formula C is present between the functional group and the silicon atom bonded to the alkoxy group_nH_2n(n represents a positive integer). In this case, the above general formula C_nH_2nThe value of n in (1) is preferably 1 or more, and particularly preferably 2 or more. The value of n is preferably 10 or less, and particularly preferably 8 or less.

Examples of the silane coupling agent having a glycidyl group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 8-glycidoxypropyltrimethoxysilane. Among them, from the viewpoint of easily achieving excellent adhesion between the adhesive layer 12 and the substrate 11, at least one of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane and 8-glycidoxypropyltrimethoxysilane is preferably used.

The silane coupling agent having a glycidyl group may be an oligomer having the above-mentioned material as a structural monomer. In this case, the epoxy equivalent of the oligomer is preferably 100g/mol or more, particularly preferably 150g/mol or more. The epoxy equivalent is preferably 1000g/mol or less, and particularly preferably 900g/mol or less. Further, the amount of the alkoxy group in the oligomer is preferably 20% by mass or more, and particularly preferably 30% by mass or more. The amount of the alkoxy group is preferably 80% by mass or less, and particularly preferably 70% by mass or less. By using such an oligomer, excellent adhesion between the adhesive layer 12 and the base material 11 can be easily achieved.

Examples of the silane coupling agent having an amino group include 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -8-aminooctyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1, 3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, hydrochloride of N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane, and the like. Among them, from the viewpoint of easily achieving excellent adhesion between the adhesive layer 12 and the substrate 11, at least one of 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and N-2- (aminoethyl) -8-aminooctyltrimethoxysilane is preferably used.

The silane coupling agents described above may be used singly or in combination of two or more.

The content of the silane coupling agent in the silicone adhesive composition is preferably 0.001 parts by mass or more, particularly preferably 0.005 parts by mass or more, and more preferably 0.01 parts by mass or more, per 100 parts by mass of the addition-reaction type silicone resin. The content is preferably 3.0 parts by mass or less, more preferably 2.0 parts by mass or less, particularly preferably 1.0 part by mass or less, and further preferably 0.5 part by mass or less, per 100 parts by mass of the addition-reaction type silicone resin. When the content of the silane coupling agent is 0.001 parts by mass or more, excellent adhesion between the adhesive layer 12 and the substrate 11 can be easily achieved. Further, by setting the content of the silane coupling agent to 3.0 parts by mass or less, the adhesive force between the adhesive sheet 1 of the present embodiment and the adherend can be suppressed from becoming excessively high, and good removability of the adhesive sheet 1 can be ensured.

(2-4) other Components

The silicone adhesive composition in the present embodiment may contain various additives such as a dispersant, a crosslinking agent, and a reaction inhibitor in addition to the above components.

(2-5) thickness of adhesive layer

The thickness of the adhesive layer 12 is preferably 5 μm or more, particularly preferably 10 μm or more, and further preferably 15 μm or more. The thickness of the adhesive layer 12 is preferably 100 μm or less, particularly preferably 75 μm or less, and more preferably 50 μm or less. When the thickness of the adhesive layer 12 is in the above range, the adhesive sheet 1 of the present embodiment easily exhibits an appropriate adhesive force to an adherend. As a result, unintended peeling of the adhesive sheet 1 from the adherend can be effectively suppressed, and at the same time, good removability of the adhesive sheet 1 can be easily achieved.

(3) Release sheet

The release sheet 13 is not particularly limited as long as it does not adversely affect the adhesive layer 12, and examples thereof include a polyethylene film, a polypropylene film, a polybutylene 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) acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, and a fluororesin film. In addition, crosslinked films of these films may also be used. Further, a laminated film of these films is also possible. Among the above, a polyethylene terephthalate film having excellent handling properties is preferable.

The surface of the release sheet 13 in contact with the adhesive layer 12 may be subjected to a release treatment. Examples of the release agent used in the release treatment include fluorine-based, alkyd-based, silicone-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

Although the thickness of the release sheet 13 is not particularly limited, it is usually preferably 15 μm or more, and particularly preferably 25 μm or more. The thickness is preferably 100 μm or less, and particularly preferably 75 μm or less.

2. Physical Properties of adhesive sheet

(1) Total light transmittance

The range of the total light transmittance of the adhesive sheet 1 of the present embodiment (in the case where the adhesive sheet 1 includes the release sheet 13, the total light transmittance of a laminate obtained by removing the release sheet 13 by peeling) is preferably adjusted depending on the type of the functional additive.

When an ultraviolet absorber is used as the functional additive, the total light transmittance is preferably 88% or more, particularly preferably 89% or more, and more preferably 90% or more. When the total light transmittance is 88% or more, the adhesive sheet 1 of the present embodiment has excellent transparency, and is very suitable as a protective sheet requiring high transparency, such as a protective sheet for an OLED device. The upper limit of the total light transmittance is not particularly limited, but is preferably 100% or less, particularly preferably 98% or less, and further preferably 94% or less.

When a blue colorant is used as the functional additive, the total light transmittance is preferably 60% or more, particularly preferably 62% or more, and more preferably 65% or more. The total light transmittance is preferably 90% or less, particularly preferably 85% or less, and further preferably 80% or less. When the total light transmittance is in these ranges, the adhesive sheet 1 can be easily colored to a desired blue color.

When a black colorant is used as the functional additive, the total light transmittance is preferably 30% or more, particularly preferably 40% or more, and more preferably 50% or more. The total light transmittance is preferably 80% or less, particularly preferably 75% or less, and more preferably 70% or less. By setting the total light transmittance to these ranges, the adhesive sheet 1 becomes easy to have a desired black color.

In the case of using an antistatic agent as the functional additive, the above total light transmittance is preferably 88% or more, particularly preferably 89% or more, and further preferably 90% or more. When the total light transmittance is 88% or more, the adhesive sheet 1 of the present embodiment has excellent transparency, and is very suitable as a protective sheet requiring high transparency, such as a protective sheet for an OLED device. The upper limit of the total light transmittance is not particularly limited, but is preferably 100% or less, particularly preferably 98% or less, and further preferably 94% or less.

When the light-diffusing fine particles are used as the functional additive, the total light transmittance is preferably 88% or more, particularly preferably 89% or more, and more preferably 90% or more. When the total light transmittance is 88% or more, the adhesive sheet 1 of the present embodiment can easily exhibit desired diffusibility. The upper limit of the total light transmittance is not particularly limited, but is preferably 100% or less, particularly preferably 98% or less, and further preferably 94% or less.

The total light transmittance is measured in accordance with JIS K7361-1:1997 and ASTM D1003, and the detailed measurement method is shown in the following description of test examples.

(2) Haze value

The range of the haze value of the adhesive sheet 1 of the present embodiment (in the case where the adhesive sheet 1 includes the release sheet 13, the haze value of the laminate obtained by removing the release sheet 13 by peeling) is preferably adjusted depending on the type of the functional additive.

When an ultraviolet absorber is used as the functional additive, the haze value is preferably 3.0% or less, particularly preferably 2.5% or less, and more preferably 2.0% or less. When the haze value is 3.0% or less, the pressure-sensitive adhesive sheet 1 of the present embodiment has excellent transparency, and is very suitable as a protective sheet requiring high transparency, such as a protective sheet for an OLED device. The lower limit of the haze value is not particularly limited, but is preferably 0.1% or more, particularly preferably 0.2% or more, and further preferably 0.3% or more.

When a blue colorant is used as the functional additive, the haze value is preferably 5% or more, particularly preferably 6% or more, and more preferably 7% or more. The haze value is preferably 30% or less, particularly preferably 28% or less, and further preferably 25% or less. When the haze value is in these ranges, the adhesive sheet 1 is likely to develop a desired blue color.

When a black colorant is used as the functional additive, the haze value is preferably 5% or more, particularly preferably 6% or more, and more preferably 7% or more. The haze value is preferably 30% or less, particularly preferably 28% or less, and further preferably 25% or less. When the haze value is in these ranges, the adhesive sheet 1 can easily have a desired black color.

When an antistatic agent is used as the functional additive, the haze value is preferably 3.0% or less, particularly preferably 2.5% or less, and further preferably 2.0% or less. When the haze value is 3.0% or less, the pressure-sensitive adhesive sheet 1 of the present embodiment has excellent transparency, and is very suitable as a protective sheet requiring high transparency, such as a protective sheet for an OLED device. The lower limit of the haze value is not particularly limited, but is preferably 0.1% or more, particularly preferably 0.2% or more, and further preferably 0.3% or more.

When the light diffusing fine particles are used as the functional additive, the haze value is preferably 20% or more, particularly preferably 25% or more, and more preferably 30% or more. The haze value is preferably 90% or less, particularly preferably 80% or less, and more preferably 70% or less. When the haze value is in these ranges, the adhesive sheet 1 of the present embodiment can easily exhibit desired diffusibility.

The haze values described above were measured in accordance with JIS K7136:2000 and ASTM D1003, and the detailed measurement methods are shown in the following test examples.

(3) Coordinates of CIELAB

In the adhesive sheet 1 of the present embodiment, it is preferable to adjust the range of each coordinate (L, a, b) of CIELAB color space (CIELAB) of the adhesive layer 12 according to the kind of the functional additive.

For example, when a black colorant is used as the functional additive for the L @ coordinate relating to brightness, it is preferably 95 or less, particularly preferably 90 or less, and still more preferably 85 or less. When the L ^ coordinate is 95 or less, the adhesive sheet 1 can easily have a desired black color. The lower limit of the L @ -coordinate is not particularly limited, but is preferably 70 or more, particularly preferably 75 or more, and further preferably 80 or more, for example.

In addition, in the case of using a blue colorant as a functional additive, the a coordinate is preferably-8.0 or more, particularly preferably-7.5 or more, and still more preferably-7.0 or more. The a-coordinate is preferably-1.0 or less, particularly preferably-1.5 or less, and further preferably-2.0 or less. When the a coordinate is in the above range, the adhesive sheet 1 is easily colored to a desired blue color.

In addition, when a blue colorant is used as the functional additive, the b-coordinate is preferably-20 or more, particularly preferably-19 or more, and still more preferably-18 or more. The b-coordinate is preferably-5.0 or less, particularly preferably-6 or less, and still more preferably-7 or less. When the b-coordinate is in the above range, the adhesive sheet 1 is easily colored to a desired blue color.

Further, when an ultraviolet absorber is used as the functional additive, the b-coordinate is preferably-1.0 or more, particularly preferably-0.8 or more, and more preferably-0.5 or more. The b-coordinate is preferably 2.0 or less, particularly preferably 1.8 or less, and more preferably 1.5 or less. When the b-coordinate is in the above range, the adhesive sheet 1 of the present embodiment has excellent transparency, and the adhesive layer 12 is less likely to develop yellow color, and thus is suitable as a protective sheet requiring high transparency, such as a protective sheet for an OLED device.

The above-described detailed measurement method of each coordinate of CIELAB is described in the following test examples.

(4) Adhesive force

In the adhesive sheet 1 of the present embodiment, the adhesive force measured when the surface of the adhesive layer 12 on the opposite side to the substrate 11 (hereinafter, sometimes referred to as "adhesive surface") is adhered to soda lime glass and then the adhesive sheet is peeled from the soda lime glass at a peeling speed of 0.3m/min is preferably 10mN/25mm or more, particularly preferably 20mN/25mm or more, and further preferably 25mN/25mm or more. When the adhesive force is 10mN/25mm or more, the adhesive sheet 1 can be prevented from being unintentionally peeled from an adherend. The above-mentioned adhesive force is preferably 300mN/25mm or less, more preferably 200mN/25mm or less, particularly preferably 100mN/25mm or less, and further preferably 50mN/25mm or less. When the adhesive force is 300mN/25mm or less, the adhesive sheet 1 can easily achieve excellent removability.

In the adhesive sheet 1 of the present embodiment, the adhesive force measured when the adhesive sheet is peeled from soda lime glass at a peeling speed of 2.0m/min after the adhesive surface is adhered to the soda lime glass is preferably 20mN/25mm or more, particularly preferably 30mN/25mm or more, and more preferably 40mN/25mm or more. The above-mentioned tack is preferably 400mN/25mm or less, more preferably 300mN/25mm or less, particularly preferably 200mN/25mm or less, and further preferably 100mN/25mm or less. By making the adhesive force at the time of peeling at a peeling speed of 2.0m/min within the above range, unintended peeling can be prevented, and particularly, excellent removability becomes easy to achieve.

These adhesive forces are measured in accordance with JIS Z0237:2009, and the detailed measurement methods thereof are shown in the following description of test examples.

The adhesive sheet 1 of the present embodiment preferably has a small difference between the adhesive force measured when peeling is performed at a peeling speed of 0.3m/min and the adhesive force measured when peeling is performed at a peeling speed of 2.0 m/min. Specifically, the absolute value of the difference between the adhesive force at a peeling rate of 2.0m/min and the adhesive force at a peeling rate of 0.3m/min is preferably 200mN/25mm or less, particularly preferably 100mN/25mm or less, and more preferably 50mN/25mm or less. When the difference in adhesive force falls within such a range, the adhesive sheet 1 is easily firmly fixed to an adherend during use and easily peeled off after use. The lower limit of the absolute value is not particularly limited, but is preferably 1mN/25mm or more, and particularly preferably 10mN/25mm or more.

(5) Surface resistivity

In the case where an antistatic agent is used as the functional additive, the surface resistivity of the pressure-sensitive adhesive sheet 1 of the present embodiment is preferably 1.0 × 10¹³Omega/sq or less, particularly preferably 8.0X 10¹²Omega/sq or less, more preferably 5.0X 10¹²Omega/sq or less. By making the surface resistivity to be 1.0X 10¹³The electrostatic peeling voltage of the pressure-sensitive adhesive sheet 1 can be easily suppressed to a low value at Ω/sq or less, and adhesion of dust due to electrostatic action and adverse electrical effects on an adherend can be easily prevented. The lower limit of the surface resistivity is not particularly limited, but is preferably 1.0 × 10⁹And omega/sq or more. The details of the method for measuring the surface resistivity are shown in the following test examples.

3. Method for producing adhesive sheet

The method for producing the adhesive sheet 1 of the present embodiment is not particularly limited. For example, the adhesive sheet 1 can be produced by applying a coating liquid containing the silicone adhesive composition and a diluent added as desired on one surface of the substrate 11, and then drying and thermosetting the obtained coating film to form the adhesive layer 12.

The diluent is not particularly limited, and various diluents can be used. For example, as the hydrocarbon compound such as toluene, hexane, heptane and the like, acetone, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, a mixture thereof and the like can be used.

The coating liquid of the silicone adhesive composition may be applied by a conventional method, for example, a bar coating method, a doctor blade coating method, a roll coating method, a blade coating method, a die coating method, or a gravure coating method. After the coating liquid is applied, the coating film is preferably dried by heating.

The conditions for the heat curing are preferably 80 ℃ to 180 ℃, and preferably 10 seconds to 150 seconds.

After the adhesive layer 12 is formed in the above manner, the release sheet 13 is bonded to the adhesive layer 12, whereby the adhesive sheet 1 can be obtained.

In the above-described manufacturing method, the adhesive layer 12 is formed on the substrate 11 first, but the substrate 11 may be bonded to the adhesive layer 12 after the adhesive layer 12 is formed on the release sheet 13.

4. Use of adhesive sheet

The application of the adhesive sheet 1 of the present embodiment is not particularly limited. As an example of such applications, there is an application as a protective sheet for preventing damage and the like of the surface of a device in the processes of processing, assembling, inspecting and the like of the device. When the adhesive sheet 1 is used for this purpose, an antistatic agent, an ultraviolet absorber, or the like is preferably used as the functional additive. When an antistatic agent is used as the functional additive, static electricity of the adhesive sheet 1 can be suppressed, and adverse effects on the device due to the static electricity can be suppressed.

Examples of the device include an optical member and an electronic member. In particular, in the adhesive sheet 1 of the present embodiment, a device to be protected is preferably a flexible device. In the adhesive sheet 1 of the present embodiment, a device to be protected is preferably a device that requires a light emission test or a high temperature condition in a state where the adhesive sheet 1 is attached. Therefore, the device to be protected using the adhesive sheet 1 of the present embodiment is preferably an OLED device, and particularly preferably a flexible OLED device.

In addition, as another application of the adhesive sheet 1 of the present embodiment, an application as a protective sheet for an end user to be attached to a display of an electronic device such as a smartphone can be cited. When the adhesive sheet 1 is used for this purpose, light diffusing fine particles, an antistatic agent, an ultraviolet absorber, and the like are preferably used as the functional additive. When the light diffusing particles are used as the functional additive, a desired optical function can be imparted to the adhesive sheet 1, and good visibility of the display can be achieved.

As another application of the adhesive sheet 1 of the present embodiment, there is an application as an adhesive sheet to be attached to glass, walls, or the like of stores or houses for decoration. When the adhesive sheet 1 is used for this purpose, an ultraviolet absorber, a colorant, or the like is preferably used as the functional additive. In the case of using an ultraviolet absorber as the functional additive, discoloration of the adhesive sheet due to long-term exposure to light can be suppressed. Further, by using a colorant as a functional additive, a desired color can be imparted to the adhesive sheet.

As still another use of the pressure-sensitive adhesive sheet 1 of the present embodiment, there is an application as a colored sheet for protecting a graphite sheet. When the adhesive sheet 1 is used for this purpose, a colorant or the like is preferably used as the functional additive. By using a colorant as a functional additive, a desired color can be imparted to the colored sheet.

The adhesive layer of the adhesive sheet 1 of the present embodiment is made of a silicone adhesive, and can achieve good removability. Therefore, when the used adhesive sheet 1 is favorably peeled off from the adherend, the problem that the adhesive from the adhesive layer 12 remains on the adherend is not caused, and the peeling can be favorably performed. In addition, when this peeling is performed, problems such as breakage or damage of the adherend can be suppressed.

Further, in the adhesive sheet 1 of the present embodiment, as described above, the adhesive layer 12 is formed of the silicone adhesive composition containing the functional additive made of the organic material. However, when the silicone adhesive composition further contains a silane coupling agent, the interface between the substrate 11 and the adhesive layer 12 has excellent adhesion. Therefore, the adhesive sheet 1 of the present embodiment can suppress unintentional peeling at the interface between the substrate 11 and the adhesive layer 12, and can suppress only the adhesive layer 12 from remaining on an adherend when the adhesive sheet 1 is peeled from the adherend. Further, even when the adhesive sheet 1 of the present embodiment is rolled up into a roll, the occurrence of tunnels or peeling at the interface between the substrate 11 and the adhesive layer 12 can be suppressed.

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

For example, another layer may be present between the substrate 11 and the adhesive layer 12 of the adhesive sheet 1, and another layer may be laminated on the surface of the substrate 11 opposite to the adhesive layer 12 side.

Examples

The present invention will be described in more detail with reference to examples and the like, but the scope of the present invention is not limited to these examples and the like.

[ example 1]

1. Preparation of coating liquid for Silicone adhesive composition

100 parts by mass (numerical value in terms of solid content, the same applies hereinafter) of an addition reaction type silicone resin (Shin-Etsu Chemical co., ltd., product name "KS-847H") as a main agent of a silicone adhesive, 2 parts by mass of a platinum CATALYST (product name "SRX 212 catalsst", ltd., product name "SRX 212 catalsst") as a silane coupling agent, 0.25 parts by mass of 8-glycidyl ether oxyoctyltrimethoxysilane as a silane coupling agent, 10 parts by mass of a silicone resin (product name "SD-4584" as a silane coupling agent), and 4.0 parts by mass of an ultraviolet absorber (2, 2-dihydroxy-4-methoxybenzophenone) as a functional additive were mixed, diluted with methyl ethyl ketone, and used as a coating liquid of a silicone adhesive composition.

2. Production of adhesive sheet

The coating liquid of the silicone adhesive composition obtained in the above step was applied to one surface of the substrate a shown in table 1 by a blade coater, and then heat treated at 130 ℃ for 2 minutes to form an adhesive layer having a thickness of 25 μm. Subsequently, a polyethylene terephthalate (PET) film (manufactured by INC., product name "Lumiror T60" without a release agent layer, thickness: 50 μm) as a release sheet was laminated on the adhesive layer to obtain an adhesive sheet.

Further, methyl ethyl ketone was dropped in a single drop onto the surface of the substrate a, and after 30 seconds, the drop was sucked by a wiper to form a depression corresponding to the drop. That is, an easy adhesion layer partially dissolved by methyl ethyl ketone is provided on the surface of the base material a. The same applies to the substrate B. On the other hand, no depression was formed in the substrate C.

Examples 2 to 7, comparative examples 1 to 5, and reference example 1

Adhesive sheets were produced in the same manner as in example 1, except that the kind of the base material, the kind and the blending amount of the silane coupling agent, and the kind and the blending amount of the functional additive were changed as shown in table 2.

[ reference example 2]

An adhesive sheet was produced in the same manner as in example 1, except that the substrate a was changed to the release sheet D shown in table 1, and at the same time, a coating liquid of a silicone-based adhesive composition was applied to the surface of the release sheet D on the fluorine-based release agent layer side to form an adhesive layer.

Table 1 shows the materials of the substrates a to C and the release sheet D used, the types of coatings provided for the substrates a to C and the release sheet D, and various physical properties measured by the following test examples.

The details of each functional additive described in table 2 are as follows.

Ultraviolet absorber: 2, 2-dihydroxy-4-methoxybenzophenone

Colorant (blue): copper phthalocyanine blue

Antistatic agent: material obtained by mixing potassium bis (fluorosulfonyl) imide and tetraethylene glycol dimethyl ether at a mass ratio of 1:1

Light diffusing particles: spherical microparticles composed of crosslinked polymethyl methacrylate (Sekisui CHEMICAL CO., LTD., product name "SSX-103", average particle diameter 3 μm)

Colorant (black): styrene-maleic acid resin dispersion of carbon Black (TOYO INK CO., LTD., product name "Multilac A-903 Black")

Inorganic filler: silica Filler (manufactured by Admatechs corporation, product name: SO-C4, average particle diameter: 1.0 μm, maximum particle diameter: 1.2 μm, shape: spherical)

[ test example 1] (measurement of Total light transmittance and haze value of substrate and Release sheet)

The base materials A to C and the release sheet D shown in Table 1 were measured for total light transmittance (%) in accordance with JIS K7361-1:1997 and ASTM D1003, and also for haze value (%) in accordance with JIS K7136:2000 and ASTM D1003, using a haze meter (NIPPON DENSHOKU INDUSTRIES Co., LTD, manufactured by product name "NDH 7000"). The results are shown in table 1.

[ test example 2] (evaluation of adhesion to substrate)

The adhesive sheets produced in examples, comparative examples and reference examples were allowed to stand at 23 ℃ and 50% RH for one day, and then the release sheet (the adhesive sheet of reference example 2, another release sheet other than release sheet D) was peeled off. Then, a cross-shaped incision (50 mm. times.50 mm) was made in the exposed adhesive layer by a cutter. Then, the adhesive layer cut into the cut portion was rubbed with the finger abdomen, and the degree of peeling of the adhesive layer was confirmed, and the adhesiveness to the base material was evaluated by the following criteria. The results are shown in Table 3.

The adhesive layer of … did not detach from the base material, and good adhesion was maintained.

Though a part of the adhesive layer is detached from the base material, Δ … can maintain a certain degree of adhesion.

The x … adhesive agent layer was entirely detached from the base material, and the adhesion was insufficient.

In addition, in the example, comparative example and reference examples in the manufacture of adhesive sheet under 85 degrees C and 85% RH conditions of seven days in the case, also in the same manner as the evaluation of substrate adhesion. The results are also shown in Table 3.

[ test example 3] (measurement of Total light transmittance and haze value of adhesive sheet)

The release sheet was peeled from the adhesive sheets produced in examples, comparative examples and reference examples (for the adhesive sheet of reference example 2, another release sheet was not the release sheet D), the total light transmittance (%) was measured in accordance with JIS K7361-1:1997 and ASTM D1003, and the haze value (%) was measured in accordance with JIS K7136:2000 and ASTM D1003 at the same time, using a haze meter (NIPPON DENSHOKU INDUSTRIES co., LTD, product name "NDH 7000"). The results are shown in Table 3.

[ test example 4] (measurement of coordinates of CIELAB)

The coordinates of the color space CIE1976(L, a, b) were measured for the adhesive layers of the adhesive sheets produced in examples, comparative examples and reference examples using a simultaneous photometry spectrocolorimeter (NIPPON DENSHOKU INDUSTRIES Co., LTD, product name "SQ 2000"). The results are shown in Table 3.

[ test example 5] (measurement of adhesive force)

The adhesive sheets produced in examples 1 to 7, comparative examples 1 to 5 and reference example 1 were cut into a length of 100mm and a width of 25 mm. Then, the release sheet was peeled from the adhesive sheet, and the exposed surface of the adhesive layer was pressed at 50 ℃ and 0.5MPa for 20 minutes to adhere to soda-lime glass. Thereafter, the sample was left under a standard atmosphere (23 ℃ C., 50% RH) for 24 hours, thereby obtaining a sample for measuring an adhesive force.

The above-mentioned sample for measuring adhesive force was measured for its adhesive force (mN/25mm) by a tensile tester (product name "TENSILON UTM-4-100" manufactured by ORIENTEC CORPORATION) at a peeling angle of 180 ℃ and a peeling speed of 0.3m/min under a standard environment (23 ℃ C., 50% RH) in accordance with JIS Z0237: 2009. The results are shown in Table 3.

Further, with respect to the sample for measuring the adhesive force obtained in the same manner as described above, the force at which the adhesive sheet was peeled from the soda-lime glass was measured as the adhesive force (mN/25mm) using a tensile tester (manufactured by ORIENTEC CORPORATION, product name "TENSILON UTM-4-100") at a peeling angle of 180 ℃ and a peeling speed of 2.0m/min under a standard environment (23 ℃, 50% RH) in accordance with JIS Z0237: 2009. The results are also shown in Table 3.

[ test example 6] (measurement of surface resistivity)

The release sheet was peeled from the adhesive sheets produced in examples, comparative examples, and reference examples (in the case of the adhesive sheet of reference example 2, the other release sheet was not the release sheet D), and the exposed surface of the adhesive layer was measured at 23 ℃ under an environment of a relative humidity of 50% using a resistivity measuring instrument (Mitsubishi analytical co., ltd., product name "Hiresta UP MCP-HT450 type") in accordance with JIS K6911: 2006, the surface resistivity (Ω/sq) was measured 10 seconds after the voltage of 100V was applied. The results are shown in Table 3.

[ Table 1]

As can be seen from Table 3: the adhesive sheets produced in the examples were excellent in removability and also excellent in adhesion to the base material of the adhesive layer.

Industrial applicability

The adhesive sheet of the present invention is suitable as, for example, a protective sheet used in processes of processing, assembling, inspecting, and the like of a flexible OLED device, an adhesive sheet for decoration, a coloring sheet for protecting a graphite sheet, and the like.

Claims

1. An adhesive sheet comprising a base and an adhesive layer laminated on one surface of the base,

the adhesive layer is formed from a silicone adhesive composition containing an organosilicon adhesive, a functional additive and a silane coupling agent, wherein the organosilicon adhesive contains an addition reaction type organosilicon resin and a platinum catalyst, the addition reaction type organosilicon resin is obtained from a first polydimethylsiloxane having at least two alkenyl groups in one molecule and a second polydimethylsiloxane having at least two hydrosilyl groups in one molecule, and the functional additive is formed from an organic material.

2. The adhesive sheet according to claim 1, wherein the functional additive is at least one of an ultraviolet absorber, a colorant, an antistatic agent, and light diffusing particles.

3. The pressure-sensitive adhesive sheet according to claim 1, wherein the silane coupling agent is contained in an amount of 0.001 parts by mass or more and 3.0 parts by mass or less based on 100 parts by mass of the addition-reaction type silicone resin.

4. The adhesive sheet according to claim 1, wherein the silicone adhesive contains a silicone resin.

5. The pressure-sensitive adhesive sheet according to claim 4, wherein the content of the silicone resin is 1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the addition reaction type silicone resin.

6. The pressure-sensitive adhesive sheet according to claim 1, wherein an easy adhesion layer is provided on a surface of the substrate on the side on which the pressure-sensitive adhesive layer is laminated.

7. The adhesive sheet according to claim 1, which is used as a protective sheet for protecting a device.

8. The adhesive sheet of claim 7, wherein said device is a flexible device.