JPWO2020145188A1 - Adhesive sheet - Google Patents

Abstract

We provide a new adhesive sheet that can show good reworkability at the initial stage of attachment to the adherend, and then the adhesive strength can be greatly increased in a short time by mild heating at about 50 ° C. To do. A pressure-sensitive adhesive sheet containing a pressure-sensitive adhesive layer is provided. The pressure-sensitive adhesive layer contains a polymer A and a polymer B which is a copolymer of a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer. This adhesive sheet exhibits an adhesive force N50 of 5N / 25 mm or more. Here, the adhesive force N50 refers to the adhesive force measured at 23 ° C. after being bonded to a stainless steel plate and held at 50 ° C. for 15 minutes.

Description

The present invention relates to an adhesive sheet.
This application claims priority under Japanese Patent Application No. 2019-001349 filed January 8, 2019, the entire contents of which are incorporated herein by reference.

The adhesive sheet is used for the purpose of adhering the adherends to each other, fixing the article to the adherend, reinforcing the adherend, and the like by firmly adhering to the adherend. Conventionally, an adhesive sheet exhibiting high adhesive strength has been used for such a purpose from the initial stage of application. Further, recently, as in Patent Documents 1 to 3, there have been proposed adhesive sheets that show low adhesive strength at the initial stage of attachment to an adherend and then can greatly increase the adhesive strength. According to the adhesive sheet having such characteristics, before the increase in the adhesive force, the adhesive sheet exhibits re-sticking property (reworkability) useful for suppressing a decrease in yield due to an error or failure to attach the adhesive sheet, and also has an adhesive force. After rising, it is possible to exhibit strong adhesiveness suitable for the original purpose of use of the adhesive sheet.

Japanese Patent Application Publication No. 2014-224227 Japanese Patent No. 5890596 Japanese Patent No. 5911153

The adhesive sheet described in the above prior art document exhibits low adhesive strength at the initial stage of application, and the adhesive strength increases to a predetermined value or more by exposing it to a high temperature of about 80 ° C. or by taking a time of about 2 days. It is configured to do. As a result, the increase in adhesive strength is controlled with high reliability. By the way, the usage mode of this kind of adhesive sheet includes the use in the manufacturing process of a product, and in such an application, a simpler process is performed from the viewpoint of improving the efficiency (production efficiency) in the manufacturing process. It may be advantageous to increase the adhesive strength. For example, if an adhesive sheet capable of increasing the adhesive strength in a short time by heating closer to room temperature (mild heating) is provided, the adhesive strength increasing treatment can be efficiently and reliably performed, so that production can be performed. It can be advantageous in terms of efficiency improvement. Since the pressure-sensitive adhesive sheet having such characteristics can be applied to an adherend that is not desirable to be exposed to a high temperature state, it can be expected to develop new applications. Therefore, the present invention can exhibit good reworkability at the initial stage of attachment to the adherend, and then the adhesive strength can be greatly increased in a short time by mild heating at about 50 ° C. The purpose is to provide a new adhesive sheet.

According to the present specification, a pressure-sensitive adhesive sheet containing a pressure-sensitive adhesive layer is provided. The pressure-sensitive adhesive layer contains a polymer A and a polymer B which is a copolymer of a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer. This adhesive sheet exhibits _{an adhesive force N 50} of 5 N / 25 mm or more. Here, the adhesive force N ₅₀ refers to the adhesive force measured at 23 ° C. after being bonded to a stainless steel plate and held at 50 ° C. for 15 minutes.

The pressure-sensitive adhesive sheet having the above structure can exhibit good reworkability at the initial stage of application based on the action of the polymer B having a polyorganosiloxane skeleton. After that, the adhesive strength can be increased to a predetermined value or more by mild heating at about 50 ° C.

_{The adhesive sheet according to some preferred embodiments has an adhesive force N 23} of 3 N / 25 mm or less, which is measured after being bonded to a stainless steel plate and held at 23 ° C. for 30 minutes. An adhesive sheet satisfying this characteristic exhibits good reworkability because the adhesive strength is suppressed to a low level at the initial stage of application. That is, it is possible to preferably achieve both the initial light peelability (reworkability) and the increase in adhesive strength after mild heating.

In the pressure-sensitive adhesive sheet according to some preferred embodiments, the pressure-sensitive adhesive force N ₅₀ is 5 times or more the _{pressure-sensitive adhesive force N 23} measured after being bonded to a stainless steel plate and held at 23 ° C. for 30 minutes. As described above, according to the adhesive sheet in which the adhesive force N ₅₀ is 5 times or more (N ₅₀ / N ₂₃ ≧ 5) with respect to the adhesive force N ₂₃ , it shows good reworkability at the initial stage of pasting and thereafter. The adhesive strength can be greatly increased by heating or the like.

_{In the adhesive sheet according to some aspects, the adhesive force N 80} measured at 23 ° C. after being bonded to a stainless steel plate and held at 80 ° C. for 5 minutes is twice or less (that is, N _{80) of the} adhesive force N _50. / N ₅₀ ≤ 2). An adhesive sheet that satisfies this characteristic is sufficiently increased in adhesive strength by mild heating at about 50 ° C., so it is necessary to expose it to a higher temperature (specifically, heating at about 80 ° C.) in order to obtain strong adhesive strength. No. According to the adhesive sheet satisfying this characteristic, the adhesive strength can be increased to the desired level more efficiently than before.

Further, the storage elastic modulus G'(150 ° C.) of the pressure-sensitive adhesive layer at 150 ° C. is preferably 10,000 Pa or more and 90,000 Pa or less. The pressure-sensitive adhesive layer satisfying the above-mentioned storage elastic modulus at 150 ° C. easily exhibits good pressure-sensitive adhesive properties, and the polymer B easily moves in the pressure-sensitive adhesive layer. The rise can be preferably realized.

In the techniques disclosed herein, the polymer A contained in the pressure-sensitive adhesive layer is typically chemically crosslinked. As a result, the pressure-sensitive adhesive sheet can exhibit good pressure-sensitive adhesive properties. Further, in the configuration in which the degree of cross-linking is limited so that the storage elastic modulus G'(150 ° C.) is equal to or less than a predetermined value, the adhesive force after mild heating is based on the mobility of the polymer B in the adhesive layer. The rise can be preferably realized. In some embodiments, the pressure-sensitive adhesive layer may contain more than 0 parts by weight and 10 parts by weight or less of the cross-linking agent with respect to 100 parts by weight of the polymer A. By using a cross-linking agent, chemical cross-linking satisfying desired properties is preferably realized, and a storage elastic modulus G'(150 ° C.) in a predetermined range can be preferably realized.

In some embodiments, the weight average molecular weight of the polymer B can be 100,000 or greater. Even in the embodiment using the polymer B having Mw of a predetermined value or more, the effect of the technique disclosed herein can be preferably realized.

In some preferred embodiments, the weight average molecular weight of the polymer B can be less than 80,000. By using the polymer B having an Mw of less than a predetermined value, it is possible to preferably realize an increase in the adhesive strength after mild heating.

In some embodiments, the content of the polymer B in the pressure-sensitive adhesive layer can be, for example, in the range of 0.5 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the polymer A. According to the content in the above range, an increase in adhesive strength after mild heating can be preferably realized.

The polymer A is preferably an acrylic polymer. According to the pressure-sensitive adhesive layer containing polymer A, which is an acrylic polymer, and polymer B, which is a copolymer of a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer, an increase in adhesive strength after mild heating is preferable. It can be realized.

In some embodiments, the acrylic polymer preferably contains a monomer having a nitrogen atom-containing ring as its monomer unit. When the polymer A containing a monomer unit having a nitrogen atom-containing ring is used in combination with the polymer B, it is possible to preferably realize an increase in adhesive strength after mild heating.

In some preferred embodiments, the monomer component for preparing the polymer B is 60% by weight or less of the (meth) acrylic monomer (monomer M2) having a homopolymer glass transition temperature of 50 ° C. or higher. Include in proportion. In the polymer B, the copolymerization ratio of the monomer M2 having a Tg of 50 ° C. or higher is limited to a predetermined value or less, so that the increase in adhesive strength after mild heating is preferably realized based on the mobility of the polymer B in the vicinity of 50 ° C. be able to. As the monomer M2, a (meth) acrylic acid alkyl ester having a homopolymer Tg of 50 ° C. or higher (that is, an alkyl (meth) acrylate) can be preferably used.

The pressure-sensitive adhesive sheet disclosed herein includes a support base material having a first surface and a second surface, and has a form in which the pressure-sensitive adhesive layer is laminated on at least the first surface of the support base material, that is, with a base material. It can be carried out in the form of an adhesive sheet. Such a pressure-sensitive adhesive sheet with a base material can be easy to handle and process. As the supporting base material, for example, a resin film having a thickness of 30 μm or more can be preferably adopted.

Further, according to the present specification, a pressure-sensitive adhesive sheet containing a pressure-sensitive adhesive layer is provided. The pressure-sensitive adhesive layer contains a polymer A and a polymer B which is a copolymer of a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer. The storage elastic modulus G'(150 ° C.) of the pressure-sensitive adhesive layer at 150 ° C. is 10,000 Pa or more and 90,000 Pa or less. According to the pressure-sensitive adhesive sheet provided with the pressure-sensitive adhesive layer satisfying the above-mentioned storage elastic modulus at 150 ° C., it is possible to exhibit good reworkability based on the action of the polymer B, and then by mild heating at about 50 ° C. Adhesive strength can be increased.

It is sectional drawing which shows typically the structure of the pressure-sensitive adhesive sheet which concerns on one Embodiment. It is sectional drawing which shows typically the structure of the pressure-sensitive adhesive sheet which concerns on another embodiment. It is sectional drawing which shows typically the structure of the pressure-sensitive adhesive sheet which concerns on another embodiment.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for the practice of the present invention are based on the teachings regarding the practice of the invention described in the present specification and the common general knowledge at the time of filing. Can be understood by those skilled in the art. The present invention can be carried out based on the contents disclosed in the present specification and the common general technical knowledge in the art.
In the following drawings, members / parts having the same function may be described with the same reference numerals, and duplicate description may be omitted or simplified. In addition, the embodiments described in the drawings are schematically for the purpose of clearly explaining the present invention, and do not necessarily accurately represent the size or scale of the actually provided product.

Further, in the present specification, the "acrylic polymer" refers to a polymer containing a monomer unit derived from a (meth) acrylic monomer in a polymer structure, and is typically a monomer derived from a (meth) acrylic monomer. A polymer containing a unit of more than 50% by weight. Further, the (meth) acrylic monomer means a monomer having at least one (meth) acryloyl group in one molecule. Here, the "(meth) acryloyl group" has the meaning of comprehensively referring to an acryloyl group and a methacryloyl group. Therefore, the concept of the (meth) acrylic monomer here may include both a monomer having an acryloyl group (acrylic monomer) and a monomer having a methacryloyl group (methacryl-based monomer). Similarly, in this specification, "(meth) acrylic acid" means acrylic acid and methacrylic acid, and "(meth) acrylate" means acrylate and methacrylate, respectively.

<Structural example of adhesive sheet>
The pressure-sensitive adhesive sheet disclosed herein is configured to include a pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet disclosed herein may be in the form of a pressure-sensitive adhesive sheet with a base material in which the pressure-sensitive adhesive layer is laminated on one side or both sides of a support base material, and is a base material-less pressure-sensitive adhesive sheet having no support base material. It may be in the form. Hereinafter, the supporting base material may be simply referred to as a "base material".

The structure of the pressure-sensitive adhesive sheet according to one embodiment is schematically shown in FIG. The pressure-sensitive adhesive sheet 1 is a single-sided pressure-sensitive adhesive sheet with a base material including a sheet-shaped support base material 10 having a first surface 10A and a second surface 10B, and an adhesive layer 21 provided on the first surface 10A side thereof. It is configured. The pressure-sensitive adhesive layer 21 is fixed to the first surface 10A side of the support base material 10. The pressure-sensitive adhesive sheet 1 is used by attaching the pressure-sensitive adhesive layer 21 to the adherend. As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 before use (that is, before being attached to the adherend) has a peelability on the side where the surface (adhesive surface) 21A of the pressure-sensitive adhesive layer 21 faces at least the pressure-sensitive adhesive layer 21. It may be a component of the pressure-sensitive adhesive sheet 100 with a peel-off liner in a form of being in contact with the peel-off liner 31 which is the surface (peeling surface). As the peeling liner 31, for example, a sheet-like base material (liner base material) having a peeling layer provided on one side thereof so that one side becomes a peeling surface can be preferably used. Alternatively, the release liner 31 is omitted, the support base material 10 having the second surface 10B as the release surface is used, and the pressure-sensitive adhesive sheet 1 is wound so that the pressure-sensitive adhesive surface 21A becomes the second surface 10B of the support base material 10. It may be in contact with each other (roll form). When the adhesive sheet 1 is attached to the adherend, the release liner 31 or the second surface 10B of the support base material 10 is peeled off from the adhesive surface 21A, and the exposed adhesive surface 21A is pressure-bonded to the adherend.

The structure of the pressure-sensitive adhesive sheet according to another embodiment is schematically shown in FIG. The pressure-sensitive adhesive sheet 2 is provided on a sheet-shaped support base material 10 having a first surface 10A and a second surface 10B, an adhesive layer 21 provided on the first surface 10A side thereof, and a second surface 10B side. It is configured as a double-sided pressure-sensitive adhesive sheet with a base material, which comprises the pressure-sensitive adhesive layer 22. The pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) 21 is fixed to the first surface 10A of the support base material 10, and the pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer) 22 is fixed to the second surface 10B of the support base material 10. There is. The pressure-sensitive adhesive sheet 2 is used by attaching the pressure-sensitive adhesive layers 21 and 22 to different parts of the adherend. The locations where the pressure-sensitive adhesive layers 21 and 22 are attached may be the respective locations of different members, or may be different locations within a single member. In the pressure-sensitive adhesive sheet 2 before use, as shown in FIG. 2, the surface (first pressure-sensitive adhesive surface) 21A of the pressure-sensitive adhesive layer 21 and the surface (second pressure-sensitive adhesive surface) 22A of the pressure-sensitive adhesive layer 22 are at least the pressure-sensitive adhesive layer 21, It can be a component of the pressure-sensitive adhesive sheet 200 with a peel-off liner in a form of contacting the peel-off liners 31 and 32 whose sides facing the 22 are the peel-off surfaces, respectively. As the release liners 31 and 32, for example, those configured by providing a release layer with a release treatment agent on one side of a sheet-shaped base material (liner base material) so that one side becomes a release surface are preferably used. obtain. Alternatively, the peeling liner 32 is omitted, and a peeling liner 31 having both sides as peeling surfaces is used, and the adhesive sheet 2 is overlapped with the peeling liner 31 and wound in a spiral shape so that the second adhesive surface 22A becomes the peeling liner 31. An adhesive sheet with a release liner in a form (roll form) in contact with the back surface of the surface may be configured.

The structure of the pressure-sensitive adhesive sheet according to still another embodiment is schematically shown in FIG. The pressure-sensitive adhesive sheet 3 is configured as a base-less double-sided pressure-sensitive adhesive sheet composed of the pressure-sensitive adhesive layer 21. The pressure-sensitive adhesive sheet 3 has a first pressure-sensitive adhesive surface 21A composed of one surface (first surface) of the pressure-sensitive adhesive layer 21 and a second pressure-sensitive adhesive surface composed of the other surface (second surface) of the pressure-sensitive adhesive layer 21. 21B and 21B are attached to different parts of the adherend and used. As shown in FIG. 3, the adhesive sheet 3 before use has the release liners 31 and 32 having the first adhesive surface 21A and the second adhesive surface) 21B having at least the side facing the adhesive layer 21 as the release surface, respectively. It may be a component of the pressure-sensitive adhesive sheet 300 with a release liner in the form of being in contact with the surface. Alternatively, the peeling liner 32 is omitted, and a peeling liner 31 having both sides as peeling surfaces is used, and the adhesive sheet 3 is overlapped with the peeling liner 31 and wound in a spiral shape so that the second adhesive surface 21B becomes the peeling liner 31. An adhesive sheet with a release liner in a form (roll form) in contact with the back surface of the surface may be configured.

The concept of the pressure-sensitive adhesive sheet here may include what is called an pressure-sensitive adhesive tape, a pressure-sensitive adhesive film, a pressure-sensitive adhesive label, or the like. The pressure-sensitive adhesive sheet may be in a roll form, a single-wafer form, or may be cut or punched into an appropriate shape according to the intended use and usage mode. The pressure-sensitive adhesive layer in the technique disclosed herein is typically formed continuously, but is not limited to this, even if it is formed in a regular or random pattern such as a dot shape or a striped shape. good.

<Adhesive layer>
The pressure-sensitive adhesive sheet disclosed herein comprises a pressure-sensitive adhesive layer containing polymer A and polymer B, which is a copolymer of a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer. Such a pressure-sensitive adhesive layer may be formed from a pressure-sensitive adhesive composition containing a polymer A which is a complete polymer or a partial polymer of a monomer raw material A and a polymer B. The form of the pressure-sensitive adhesive composition is not particularly limited, and may be various forms such as a solvent type, a water-dispersed type, a hot melt type, and an active energy ray-curable type (for example, a photocurable type).

(Polymer A)
Examples of the polymer A include acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluoropolymers known in the field of adhesives in the room temperature range. One or more of various polymers exhibiting rubber elasticity can be used. In the pressure-sensitive adhesive sheet disclosed herein, polymer A is typically a component that occupies more than 50% by weight of the main component of the polymer component contained in the pressure-sensitive adhesive layer, for example, 75% by weight or more of the above-mentioned polymer component. Can be a component that occupies. In some embodiments, the polymer A is a component that occupies more than 50% by weight of the entire pressure-sensitive adhesive layer, and may be a component that occupies 70% by weight or more.

Glass transition temperature T _A of the polymer A may be not particularly limited, the preferred characteristics in the PSA sheet disclosed herein is selected to obtain. In some embodiments, T _A is the polymer A can be preferably used less than 0 ° C.. Since the pressure-sensitive adhesive containing the polymer A exhibits appropriate fluidity (for example, the motility of the polymer chains contained in the pressure-sensitive adhesive), the pressure-sensitive adhesive sheet whose adhesive strength increases to a predetermined value or more by mild heating. Suitable for realization. PSA sheet disclosed herein, _{T A} is less than -10 ° C., less than -20 ° C., can be preferably carried out using polymer A below -30 ° C. or less than -35 ° C.. In some embodiments, _{T A} may be less than -40 ° C., may be less than -50 ° C.. The lower limit of T _A is not particularly limited. From the viewpoint of material availability improve cohesion ease and pressure-sensitive adhesive layer, usually, T _A is -80 ° C. or higher, can be preferably used a -70 ° C. or higher, or -65 ° C. or more polymers A. In some embodiments, _{T A,} for example may be at -63 ° C. or higher may be at -55 ° C. or higher may be at -50 ° C. or higher, or at -45 ° C. or higher.

Here, in this specification, the glass transition temperature (Tg) of a polymer is a nominal value described in literature, catalogs, etc., or by the Fox formula based on the composition of the monomer raw material used for preparing the polymer. It means the required Tg. As shown below, the Fox formula is a relational formula between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer.
1 / Tg = Σ (Wi / Tgi)
In the Fox formula, Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio based on the weight), and Tgi is the homopolymer of the monomer i. Represents the glass transition temperature (unit: K) of. When the target polymer for specifying Tg is a homopolymer, the Tg of the homopolymer and the Tg of the target polymer are the same.

As the glass transition temperature of the homopolymer used for calculating Tg, the value described in the publicly known material shall be used. Specifically, the figures are listed in the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989). For the monomers for which multiple types of values are described in the Polymer Handbook, the highest value is adopted.

As the glass transition temperature of the homopolymer of the monomer not described in the above Polymer Handbook, the value obtained by the following measuring method shall be used.
Specifically, in a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, 100 parts by weight of a monomer, 0.2 parts by weight of 2,2'-azobisisobutyronitrile and acetic acid as a polymerization solvent. Add 200 parts by weight of ethyl and stir for 1 hour while flowing nitrogen gas. After removing oxygen in the polymerization system in this way, the temperature is raised to 63 ° C. and the reaction is carried out for 10 hours. Then, the mixture is cooled to room temperature to obtain a homopolymer solution having a solid content concentration of 33% by weight. Next, this homopolymer solution is cast-coated on a release liner and dried to prepare a test sample (sheet-shaped homopolymer) having a thickness of about 2 mm. This test sample is punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and shear strain with a frequency of 1 Hz using a viscoelasticity tester (manufactured by TA Instruments Japan, model name "ARES"). The viscoelasticity is measured in a shear mode at a temperature range of −70 ° C. to 150 ° C. and a temperature rise rate of 5 ° C./min, and the temperature corresponding to the peak top temperature of tan δ is defined as Tg of the homopolymer.

Although not particularly limited, the weight-average molecular weight of the polymer A (Mw) is usually suitably be at about 20 × 10 ⁴ or more. According to the polymer A of Mw, it is easy to obtain a pressure-sensitive adhesive showing good cohesiveness. From the viewpoint of obtaining a higher cohesive force, in some embodiments, Mw of the polymer A may be for example 30 × 10 ⁴ or more, may be a 40 × 10 ⁴ or more, may be a 50 × 10 ⁴ or more, 60 × may be 10 ⁴ or more, it may be 80 × 10 ⁴ or more. Also, Mw of the polymer A is generally suitably be at about 500 × 10 ⁴ or less. Since the polymer A of Mw easily forms an adhesive exhibiting appropriate fluidity (movability of polymer chains), a pressure-sensitive adhesive sheet having low adhesive strength at the initial stage of application and high adhesive strength after mild heating can be realized. Suitable for. It is preferable that the Mw of the polymer A is not too high from the viewpoint of improving the compatibility with the polymer B. In some embodiments, Mw of the polymer A is, for example may be a 250 × 10 ⁴ or less, may be a 200 × 10 ⁴ or less, may be 0.99 × 10 ⁴ or less.

In this specification, the Mw of the polymer A and the polymer B described later can be obtained by gel permeation chromatography (GPC) in terms of polystyrene. More specifically, Mw can be measured according to the methods and conditions described in the examples described later.

As the polymer A in the pressure-sensitive adhesive sheet disclosed herein, an acrylic polymer can be preferably adopted. When an acrylic polymer is used as the polymer A, good compatibility with the polymer B tends to be easily obtained. Good compatibility between the polymer A and the polymer B is preferable because it can contribute to the reduction of the initial adhesive force and the improvement of the adhesive force after heating through the improvement of the mobility of the polymer B in the pressure-sensitive adhesive layer.

The acrylic polymer is, for example, a polymer containing 50% by weight or more of a monomer unit derived from (meth) acrylic acid alkyl ester, that is, 50 out of the total amount of the monomer component (monomer raw material A) for preparing the acrylic polymer. It can be a polymer in which% by weight or more is a (meth) acrylic acid alkyl ester. As the (meth) acrylic acid alkyl ester, a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms (that is, C _{1-20) can be preferably used.} Since it is easy to balance the characteristics, _{the ratio of the (meth) acrylic acid C 1-20} alkyl ester in the monomer raw material A may be, for example, 50% by weight or more, 60% by weight or more, or 70% by weight or more. But it may be. For the same reason, the proportion of the (meth) acrylic acid C _1-20 alkyl ester in the monomer raw material A may be, for example, 99.9% by weight or less, 98% by weight or less, or 95% by weight or less. .. In some embodiments, the proportion of the (meth) acrylic acid C _1-20 alkyl ester in the monomer raw material A may be, for example, 90% by weight or less, 85% by weight or less, or 80% by weight or less.

Non-limiting specific examples of the (meth) acrylic acid C _1-20 alkyl ester include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, and isopropyl (meth) acrylic acid. N-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, (meth) Hexyl acrylate, (meth) heptyl acrylate, (meth) octyl acrylate, (meth) 2-ethylhexyl acrylate, (meth) isooctyl acrylate, (meth) nonyl acrylate, (meth) isononyl acrylate, (meth) ) Decyl acrylate, (meth) isodecyl acrylate, (meth) undecyl acrylate, (meth) dodecyl acrylate, (meth) tridecyl acrylate, (meth) tetradecyl acrylate, (meth) pentadecyl acrylate, (meth) Examples thereof include hexadecyl acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecil (meth) acrylate, and eicocil (meth) acrylate.

Of these, it is preferable to use at least (meth) acrylic acid C _1-18 alkyl ester, and it is more preferable to use at least (meth) acrylic acid C _{1-14 alkyl ester.} In some embodiments, the acrylic polymer is at least one selected from _{(meth) acrylic acid C 4-12} alkyl esters (preferably acrylic acid C _4-10 alkyl esters, eg acrylic acid C _{6-10 alkyl esters).} Can be contained as a monomer unit. For example, an acrylic polymer containing one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA) is preferable, and an acrylic polymer containing at least 2EHA is particularly preferable. Examples of other (meth) acrylic acid C _1-18 alkyl esters that may be preferably used are methyl acrylate, methyl methacrylate (MMA), n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA). , Isostearyl acrylate (ISTA) and the like.

The monomer raw material A may contain a (meth) acrylic acid alkyl ester as a main component and, if necessary, another monomer (copolymerizable monomer) copolymerizable with the (meth) acrylic acid alkyl ester. .. As the copolymerizable monomer, a monomer having a polar group (for example, a carboxy group, a hydroxyl group, a nitrogen atom-containing ring, etc.) can be preferably used. Monomers having polar groups can be useful for introducing cross-linking points in the acrylic polymer and for enhancing the cohesive force of the acrylic polymer. The copolymerizable monomer may be used alone or in combination of two or more.

Non-limiting specific examples of the copolymerizable monomer include the following.
Hydroxyl-containing monomers: For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic. 4-Hydroxybutyl acid, 6-hydroxyhexyl (meth) acrylic acid, 8-hydroxyoctyl (meth) acrylic acid, 10-hydroxydecyl (meth) acrylic acid, 12-hydroxylauryl (meth) acrylic acid, (4-hydroxy) Methylcyclohexyl) Methyl (meth) acrylate and the like (meth) hydroxyalkyl acrylate and the like.
Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N- Vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloyl piperidine, N- (meth) acryloylpyrrolidin, N-vinylmorpholin, N-vinyl-3. -Morholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxadin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N-vinylisoxazole, N-vinyl Thiasol, N-vinylisothiazole, N-vinylpyridazine, etc .;
Monomers having a succinimide skeleton, such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyhexamethylene succinimide;
Maleimides such as, for example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide; and
For example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, etc. Itaconimides.
Monomer containing carboxy group: For example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid and the like.
Acid anhydride group-containing monomer: For example, maleic anhydride, itaconic anhydride.
Epoxide group-containing monomer: For example, epoxy group-containing acrylate such as (meth) glycidyl acrylate and -2-ethyl glycidyl ether (meth) acrylate, allyl glycidyl ether, glycidyl ether (meth) acrylate and the like.
Cyano group-containing monomer: For example, acrylonitrile, methacrylonitrile, etc.
Isocyanate group-containing monomer: For example, 2-isocyanatoethyl (meth) acrylate and the like.
Amide group-containing monomers: For example, (meth) acrylamide; N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth). N, N-dialkyl (meth) acrylamide, such as acrylamide, N, N-di (n-butyl) (meth) acrylamide, N, N-di (t-butyl) (meth) acrylamide; N-ethyl (meth) N-alkyl (meth) acrylamides such as acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, Nn-butyl (meth) acrylamide; N-vinylcarboxylic acid amides such as N-vinylacetamide. Classes; monomers having a hydroxyl group and an amide group, such as N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth). Acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, N- (4-hydroxybutyl) ( N-hydroxyalkyl (meth) acrylamide, such as meta) acrylamide; monomers with an alkoxy group and an amide group, such as N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-butoxymethyl ( N-alkoxyalkyl (meth) acrylamide such as meta) acrylamide; In addition, N, N-dimethylaminopropyl (meth) acrylamide, N- (meth) acryloylmorpholine and the like.
Aminoalkyl (meth) acrylates: For example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, t (meth) acrylate. -Butylaminoethyl.
Alkoxy group-containing monomers: for example, 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, (meth) acrylic acid. Alkoxyalkyls (meth) acrylates such as butoxyethyl, ethoxypropyl (meth) acrylates; alkoxyalkylene glycols (meth) acrylates such as methoxyethylene glycol (meth) acrylates, methoxypolypropylene glycols (meth) acrylates, etc. Kind.
Monomer containing a sulfonic acid group or a phosphate group: for example, styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonic acid, 2- (meth) acrylamide-2-methyl propane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfo. Propyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid, 2-hydroxyethyl acryloyl phosphate, etc.
(Meta) acrylic acid ester having an alicyclic hydrocarbon group: For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate and the like.
(Meta) acrylic acid ester having an aromatic hydrocarbon group: For example, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate and the like.
Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.
Vinyl esters: For example, vinyl acetate, vinyl propionate, etc.
Aromatic vinyl compounds: For example, styrene, α-methylstyrene, vinyltoluene and the like.
Olefins: For example, ethylene, butadiene, isoprene, isobutylene and the like.
In addition, heterocyclic-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate, halogen atom-containing (meth) acrylates such as vinyl chloride and fluorine atom-containing (meth) acrylates, and silicon atom-containing silicone (meth) acrylates. (Meta) acrylate, (meth) acrylic acid ester obtained from terpene compound derivative alcohol, etc.

When such a copolymerizable monomer is used, the amount used is not particularly limited, but it is usually appropriate to use 0.01% by weight or more of the monomer raw material A. From the viewpoint of better exerting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer used may be 0.1% by weight or more of the monomer raw material A or 1% by weight or more. The amount of the copolymerizable monomer used can be 50% by weight or less of the monomer raw material A, preferably 45% by weight or less. This prevents the cohesive force of the adhesive from becoming too high, and can improve the tackiness at room temperature (25 ° C.). In some embodiments, the amount of the copolymerizable monomer used may be 40% by weight or less of the monomer raw material A, or 35% by weight or less.

In some embodiments, the monomer raw material A may comprise a monomer having a nitrogen atom-containing ring. By using a monomer having a nitrogen atom-containing ring, the cohesive force and polarity of the adhesive can be adjusted, and the adhesive force after mild heating can be suitably improved. By including the monomer having a nitrogen atom-containing ring in the monomer raw material A, the compatibility between the polymer A formed from the monomer raw material A and the polymer B tends to be improved. This makes it easier to obtain an adhesive sheet that can greatly increase the adhesive strength by mild heating.

The monomer having a nitrogen atom-containing ring can be appropriately selected from the above examples, and can be used alone or in combination of two or more. In some embodiments, the monomer raw material A may contain, as a monomer having a nitrogen atom-containing ring, at least one monomer selected from the group consisting of N-vinyl cyclic amide represented by the following general formula (M1). preferable. The monomer raw material A may contain only one or more of such N-vinyl cyclic amides as a monomer having a nitrogen atom-containing ring.

ここで、上記一般式（Ｍ１）中のＲ^１は、２価の有機基である。

^{Here, R 1} in the above general formula (M1) is a divalent organic group.

Specific examples of N-vinyl cyclic amide include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, and N-vinyl-1,3. -Oxazine-2-one, N-vinyl-3,5-morpholindione and the like can be mentioned. Particularly preferred are N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactam.

The amount of the monomer having a nitrogen atom-containing ring is not particularly limited, and is usually 0.01% by weight or more (preferably 0.1% by weight or more, for example 0.5% by weight or more) of the monomer raw material A. Is appropriate. In some embodiments, the amount of the monomer having a nitrogen atom-containing ring used may be 1% by weight or more, 5% by weight or more, 10% by weight or more, or 12% by weight or more of the monomer raw material A. May be. Further, from the viewpoint of improving the tack feeling at room temperature (25 ° C.) and improving the flexibility at low temperature, it is usually appropriate that the amount of the monomer having a nitrogen atom-containing ring used is 40% by weight or less of the monomer raw material A. Yes, it may be 30% by weight or less, 20% by weight or less, or 18% by weight or less.

In some preferred embodiments, the monomer raw material A comprises a hydroxyl group-containing monomer. By using the hydroxyl group-containing monomer, the cohesive force and polarity of the adhesive can be adjusted, and the adhesive force after mild heating can be suitably improved. Further, the hydroxyl group-containing monomer provides a reaction point with a cross-linking agent (for example, an isocyanate-based cross-linking agent) described later, and the cohesive force of the pressure-sensitive adhesive can be enhanced by the cross-linking reaction.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and N- (2-hydroxyethyl) (meth) acrylamide. It can be suitably used. Among them, preferred examples include 2-hydroxyethyl acrylate (HEA), 4-hydroxybutyl acrylate (4HBA), and N- (2-hydroxyethyl) acrylamide (HEAA).

The amount of the hydroxyl group-containing monomer used is not particularly limited, and is usually preferably 0.01% by weight or more (preferably 0.1% by weight or more, for example 0.5% by weight or more) of the monomer raw material A. .. In some embodiments, the amount of the hydroxyl group-containing monomer used may be 1% by weight or more of the monomer raw material A, 5% by weight or more, or 10% by weight or more. Further, from the viewpoint of the mobility of the polymer B in the pressure-sensitive adhesive layer, the improvement of the tack feeling at room temperature (25 ° C.), and the improvement of the flexibility at low temperature, the amount of the hydroxyl group-containing monomer used is usually 40 of the monomer raw material A. It is appropriate that the weight is 30% by weight or less, 30% by weight or less, 20% by weight or less, 10% by weight or less, or 5% by weight or less.

In some embodiments, as the copolymerizable monomer, a monomer having a nitrogen atom-containing ring (for example, N-vinyl cyclic amide) and a hydroxyl group-containing monomer can be used in combination. In this case, the total amount of the monomer having a nitrogen atom-containing ring and the hydroxyl group-containing monomer can be, for example, 0.1% by weight or more of the monomer raw material A, may be 1% by weight or more, and may be 5% by weight or more. It may be 10% by weight or more, 15% by weight or more, 20% by weight or more, or 25% by weight or more. Further, the total amount of the monomer having a nitrogen atom-containing ring and the hydroxyl group-containing monomer can be, for example, 50% by weight or less of the monomer raw material A, and is preferably 40% by weight or less.

In embodiments that include a combination of a monomer and a hydroxyl group-containing monomer monomer material A has a nitrogen atom-containing ring, the content of the monomer having a nitrogen atom-containing ring in the monomer raw material A (W _N) and the content of the hydroxyl group-containing monomer ( W _OH) relationship with (by weight) is not particularly limited. W _N / W _OH may be, for example, 0.01 or more, usually 0.05 or more, 0.1 or more, 0.2 or more, 0.5 or more, and 0. It may be 0.7 or more. Further, W _N / W _OH may be, for example, 100 or less, usually 20 or less, 10 or less, 5 or less, 2 or less, or 1.5 or less.

In some embodiments, the monomer raw material A does not contain a monomer having a polyorganosiloxane skeleton (monomer S1) which is preferably used as a constituent component of the monomer raw material B described later, or the content of the monomer is the monomer raw material A. It is preferably less than 10% by weight (more preferably less than 5% by weight, for example, less than 2% by weight). According to the monomer raw material A having such a composition, a pressure-sensitive adhesive sheet that preferably achieves both initial reworkability and strong adhesiveness after an increase in adhesive strength can be preferably realized. For the same reason, in some other embodiments, the monomer raw material A does not contain the monomer S1 or, if it contains the monomer S1, its content (weight basis) is higher than the content of the monomer S1 in the monomer raw material B. Low is preferable.

The method for obtaining the polymer A is not particularly limited, and various polymerization methods such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, and a photopolymerization method can be appropriately adopted. In some embodiments, the solution polymerization method may be preferably employed. The polymerization temperature at the time of solution polymerization can be appropriately selected depending on the type of the monomer and solvent used, the type of the polymerization initiator and the like, and is, for example, about 20 ° C. to 170 ° C. (typically 40 ° C. to 140 ° C.). ℃).

The initiator used for the polymerization can be appropriately selected from conventionally known thermal polymerization initiators, photopolymerization initiators and the like, depending on the polymerization method. The polymerization initiator may be used alone or in combination of two or more.

Examples of the thermal polymerization initiator include azo-based polymerization initiators (for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis (for example). 2-Methylpropionic acid) dimethyl, 4,4'-azobis-4-cyanovalerian acid, azobisisobutyvaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2 -(5-Methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'-dimethylene) Isobutylamidin) dihydrochloride, etc.); Persulfate such as potassium persulfate; Peroxide-based polymerization initiator (for example, dibenzoylperoxide, t-butylpermalate, lauroyl peroxide, etc.); Redox-based polymerization initiator, etc. Can be mentioned. The amount of the thermal polymerization initiator used is not particularly limited, but is, for example, 0.01 parts by weight to 5 parts by weight, preferably 0 with respect to 100 parts by weight of the monomer component (monomer raw material A) used for preparing the acrylic polymer. The amount can be in the range of 0.05 parts by weight to 3 parts by weight.

The photopolymerization initiator is not particularly limited, and is, for example, a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, and photoactivity. Oxym-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzyl-based photopolymerization initiator, benzophenone-based photopolymerization initiator, Ketal-based photopolymerization initiator, thioxanthone-based photopolymerization initiator, acylphosphine oxide-based photopolymerization initiator Agents and the like can be used. The amount of the photopolymerization initiator used is not particularly limited, but is, for example, an amount in the range of 0.01 parts by weight to 5 parts by weight, preferably 0.05 parts by weight to 3 parts by weight with respect to 100 parts by weight of the monomer raw material A. Can be.

In some embodiments, the polymer A is a partial polymer (polymer syrup) obtained by irradiating a mixture of the above-mentioned monomer raw material A with a polymerization initiator with ultraviolet rays (UV) to polymerize a part of the monomer components. ) Can be included in the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer. A pressure-sensitive adhesive composition containing such a polymer syrup can be applied to a predetermined object to be coated and irradiated with ultraviolet rays to complete the polymerization. That is, the polymer syrup can be grasped as a precursor of the polymer A. The pressure-sensitive adhesive layer disclosed herein can be formed, for example, by using a pressure-sensitive adhesive composition containing the above-mentioned polymer syrup and polymer B.

(Polymer B)
The polymer B in the technique disclosed herein is a copolymer of a monomer having a polyorganosiloxane skeleton (hereinafter, also referred to as “monomer S1”) and a (meth) acrylic monomer. The polymer B has a low polarity and motility of the polyorganosiloxane structure derived from the monomer S1 to suppress the adhesive force at the initial stage of attachment to the adherend, and the adhesive force to increase the adhesive force to the adherend by heating. Can function as a rise retarder. The monomer S1 is not particularly limited, and any monomer containing a polyorganosiloxane skeleton can be used. Monomer S1 promotes uneven distribution of polymer B on the surface of the pressure-sensitive adhesive layer on the pressure-sensitive adhesive sheet before use (before attachment to the adherend) due to its low polarity due to its structure, and light peeling at the initial stage of bonding. Expresses sex (low adhesiveness). As the monomer S1, a monomer having a structure having a polymerizable reactive group at one end can be preferably used. By copolymerization of the monomer S1 and the (meth) acrylic monomer, a polymer B having a polyorganosiloxane skeleton in the side chain is formed. The polymer B having such a structure tends to have a low initial adhesive strength and a high adhesive strength after mild heating due to the motility and mobility of the side chains. Further, in some embodiments, the monomer S1 preferably has a polymerizable reactive group at one end and does not have a functional group that causes a cross-linking reaction with the polymer A at the other end. The polymer B in which the monomer S1 having such a structure is copolymerized tends to have a low initial adhesive force and a high adhesive force after heating due to the motility of the polyorganosiloxane structure derived from the monomer S1.

ここで、上記一般式（１），（２）中のＲ^３は水素またはメチルであり、Ｒ^４はメチル基または１価の有機基であり、ｍおよびｎは０以上の整数である。As the monomer S1, for example, a compound represented by the following general formula (1) or (2) can be used. More specifically, examples of the one-ended reactive silicone oil manufactured by Shin-Etsu Chemical Co., Ltd. include X-22-174ASX, X-22-2426, X-22-2475, and KF-22012. Monomer S1 can be used alone or in combination of two or more.

^{Here, R 3} in the above general formulas (1) and (2) is hydrogen or methyl, R ⁴ is a methyl group or a monovalent organic group, and m and n are integers of 0 or more.

The functional group equivalent of the monomer S1 can be an appropriate value within a range in which the desired effect is exhibited by using the monomer S1, and is not limited to a specific range. From the viewpoint of sufficiently suppressing the initial adhesive force, the functional group equivalent is, for example, 100 g / mol or more, 200 g / mol or more, 300 g / mol or more (for example, 500 g / mol or more), and 700 g. It is preferably / mol or more, more preferably 800 g / mol or more, further preferably 850 g / mol or more, and particularly preferably 1500 g / mol or more. In some embodiments, the functional group equivalent may be 3000 g / mol or more, 4500 g / mol or more, or 6000 g / mol, from the viewpoint of achieving both low adhesiveness at the initial stage of application and increase in adhesive strength after mild heating. It may be mol or more, 9000 g / mol or more, 12000 g / mol or more, or 15000 g / mol or more (for example, 16000 g / mol or more). The functional group equivalent of the monomer S1 can be, for example, 50,000 g / mol or less. From the viewpoint of sufficiently increasing the adhesive strength, the functional group equivalent is preferably, for example, 30,000 g / mol or less, and more preferably 20,000 g / mol or less. In some embodiments, the functional group equivalent of the monomer S1 may be less than 18,000 g / mol, less than 15,000 g / mol, less than 10,000 g / mol, less than 6000 g / mol, less than 5000 g / mol. .. When the functional group equivalent of the monomer S1 is within the above range, the compatibility (for example, compatibility with the base polymer) and the mobility in the pressure-sensitive adhesive layer can be easily adjusted to an appropriate range, and the initial low adhesiveness and mildness can be easily adjusted. It becomes easy to realize an adhesive layer that achieves both an increase in adhesive strength after heating.

Non-limiting examples of the preferred range of the functional group equivalent of the monomer S1 are 700 g / mol or more and 50,000 g / mol or less, 700 g / mol or more and 30,000 g / mol or less, 700 g / mol or more and 20,000 g / mol or less, 700 g / mol or more and 18,000 g. It includes less than / mol, 700 g / mol or more and less than 15,000 g / mol, 800 g / mol or more and less than 10,000 g / mol, and 850 g / mol or more and less than 6000 g / mol, 1500 g / mol or more and less than 5000 g / mol. In some embodiments, the preferred range of functional group equivalent of monomer S1 is 3000 g / mol or more and 50,000 g / mol or less, 6000 g / mol or more and 50,000 g / mol or less, 12000 g / mol or more and 50,000 g / mol or less, 15,000 g / mol or more and 50,000 g / mol or less. It can be less than or equal to mol.

Here, the "functional group equivalent" means the weight of the main skeleton (for example, polydimethylsiloxane) bonded to each functional group. The title unit g / mol is converted to 1 mol of functional group. The functional group equivalent of the monomer S1 ^{can be calculated, for example, from the spectral intensity of 1} H-NMR (proton NMR) based on nuclear magnetic resonance (NMR). ¹ The calculation of the functional group equivalent (g / mol) of the monomer S1 based on the spectral intensity of ^{1 H-NMR is based on the general structural analysis method related to 1 1} H-NMR spectral analysis, and if necessary, the Japanese Patent No. 1 This can be done with reference to the description in Publication No. 5591153.

When two or more kinds of monomers having different functional group equivalents are used as the monomer S1, an arithmetic mean value can be used as the functional group equivalent of the monomer S1. That is, the functional group equivalent of the monomer S1 composed of n kinds of monomers having different functional group equivalents (monomer S1 _{1 , monomer S1 2} ... Monomer S1 _n ) can be calculated by the following formula.
Functional group equivalent of the monomer S1 (g / mol) = (monomer S1 ₁ functional group equivalent × monomer S1 ₁ of the amount + monomer S1 ₂ functional group equivalent × monomer S1 ₂ of the amount + ... + monomer S1 _n Functional group equivalent amount × amount of monomer S1 _n ) / (amount of monomer S1 ₁ + amount of monomer S1 ₂ + ... + amount of monomer S1 _n )

As the content of the monomer S1, an appropriate value can be adopted within a range in which the desired effect is exhibited by using the monomer S1, and the content is not limited to a specific range. In some embodiments, the total amount of the monomer component (monomer raw material B) for preparing the polymer B may be, for example, 5% by weight or more, from the viewpoint of better exerting the effect as an adhesive force increase retarder. It is preferably 10% by weight or more, 15% by weight or more, or 20% by weight or more. Further, the content of the monomer S1 in the monomer raw material B may be, for example, 80% by mass or less, preferably 60% by weight or less, and 50% by weight or less, from the viewpoint of polymerization reactivity and compatibility. It may be 40% by weight or less, or 30% by weight or less. If the content of the monomer S1 is less than 5% by weight, the initial adhesive strength may not be sufficiently suppressed. If the content of the monomer S1 is more than 60% by weight, the increase in adhesive strength may be insufficient.

The monomer raw material B contains, in addition to the monomer S1, a (meth) acrylic monomer copolymerizable with the monomer S1. By copolymerizing one or more (meth) acrylic monomers with the monomer S1, the mobility of the polymer B in the pressure-sensitive adhesive layer can be suitably adjusted. Copolymerizing the monomer S1 with the (meth) acrylic monomer can also help improve the compatibility between the polymer B and the polymer A (for example, the acrylic polymer).

Examples of the (meth) acrylic monomer that can be used for the monomer raw material B include (meth) acrylic acid alkyl esters. For example, one or more of the monomers exemplified above as the (meth) acrylic acid alkyl ester that can be used when the polymer A is an acrylic polymer can be used as a constituent component of the monomer raw material B. In some embodiments, the monomer raw material B is a (meth) acrylic acid C _4-12 alkyl ester (preferably a (meth) acrylic acid C _4-10 alkyl ester, eg, a (meth) acrylic acid C _6-10 alkyl ester). Can contain at least one of. In some other embodiments, the monomer raw material B may contain at least one of _{a methacrylic acid C 1-18} alkyl ester (preferably a methacrylic acid C _1-14 alkyl ester, such as a methacrylic acid C _{1-10 alkyl ester).} .. The monomer raw material B may contain, for example, one or more selected from MMA, BMA and 2EHMA as the (meth) acrylic monomer.

As another example of the above (meth) acrylic monomer, a (meth) acrylic acid ester having an alicyclic hydrocarbon group can be mentioned. For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, 1-adamantyl (meth) acrylate and the like can be used. In some embodiments, the monomer raw material B may contain, as the (meth) acrylic monomer, at least one selected from dicyclopentanyl methacrylate, isobornyl methacrylate and cyclohexyl methacrylate.

The content of the (meth) acrylic acid alkyl ester and the (meth) acrylic acid ester having an alicyclic hydrocarbon group in the monomer raw material B may be, for example, 10% by weight or more and 95% by weight or less, and may be 20% by weight. It may be 95% by weight or less, 30% by weight or more and 90% by weight or less, 40% by weight or more and 90% by weight or less, and 50% by weight or more and 85% by weight or less. May be good. From the viewpoint of easiness of increasing the adhesive strength by mild heating, the use of (meth) acrylic acid alkyl ester may be advantageous. In some embodiments, the content of the (meth) acrylic acid ester having an alicyclic hydrocarbon group may be less than 50% by weight, less than 30% by weight, or less than 15% by weight of the monomer raw material B. It may be less than 10% by weight or less than 5% by weight. It is not necessary to use a (meth) acrylic acid ester having an alicyclic hydrocarbon group.

In some preferred embodiments, the (meth) acrylic monomer, which is a constituent of the monomer raw material B, may contain a monomer M2 having a homopolymer Tg of 50 ° C. or higher. In the polymer B, by copolymerizing the monomer S1 and the monomer M2, the motility and mobility of the polyorganosiloxane structural portion with increasing temperature are suitably controlled, and the initial light peelability (reworkability) and after mild heating are performed. It is easy to achieve both the increase in adhesive strength and the increase in adhesive strength. In some embodiments, the Tg of the homopolymer of the monomer M2 may be 60 ° C. or higher, 70 ° C. or higher, 80 ° C. or higher, or 90 ° C. or higher. The upper limit of Tg of the homopolymer of the monomer M2 is not particularly limited, but it is usually appropriate to be 200 ° C. or lower from the viewpoint of ease of synthesis of the polymer B and the like. In some embodiments, the Tg of the homopolymer of the monomer M2 may be, for example, 180 ° C or lower, 150 ° C or lower, or 120 ° C or lower.

As the monomer M2, for example, among the (meth) acrylic monomers exemplified above, those in which the Tg of the homopolymer satisfies the condition can be used. For example, one or more monomers selected from the group consisting of (meth) acrylic acid alkyl esters and (meth) acrylic acid esters having an alicyclic hydrocarbon group can be used. As the (meth) acrylic acid alkyl ester, a methacrylic acid alkyl ester in which the number of carbon atoms of the alkyl group is in the range of 1 to 4 can be preferably adopted.

In the embodiment in which the monomer raw material B contains the monomer M2, the content of the monomer M2 may be, for example, 5% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight or more of the monomer raw material B. However, it may be 25% by weight or more, or 30% by weight or more. In some embodiments, the content of the monomer M2 may be 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, 55% by weight or more of the monomer raw material B. But it may be. The content of the monomer M2 may be, for example, 90% by weight or less, usually 80% by weight or less, preferably 75% by weight or less, 70% by weight or less, and 65% by weight. It may be less than%. In some preferred embodiments, the content of the monomer M2 is 60% by weight or less (eg, 50% by weight or less, typically 42% by weight or less). In the polymer B, the copolymerization ratio of the monomer M2 having a Tg of 50 ° C. or higher is limited to a predetermined value or less, so that the increase in adhesive strength after mild heating is preferably realized based on the mobility of the polymer B in the vicinity of 50 ° C. be able to. From the same viewpoint, the content of the monomer M2 in the monomer raw material B may be 35% by weight or less, 25% by weight or less, or 15% by weight or less (for example, 5% by weight or less).

The content of the monomer M2 is, for example, one or more monomers selected from the group consisting of the (meth) acrylic acid alkyl ester and the (meth) acrylic acid ester having the alicyclic hydrocarbon group. It can be preferably applied in an embodiment consisting of one or more monomers in which the monomer M2 is selected from a (meth) acrylic acid alkyl ester (for example, a methacrylic acid alkyl ester). As a preferred example of such an embodiment, there is an embodiment in which the above-mentioned monomer M2 is composed of MMA.

In some embodiments, the (meth) acrylic monomer may include a monomer M3 in which the Tg of the homopolymer is less than 50 ° C (typically −20 ° C or higher and lower than 50 ° C). By using the monomer M3, it becomes easy to obtain an adhesive sheet having both adhesive force and cohesive force in a well-balanced manner after the adhesive force is increased. From the viewpoint of facilitating the exertion of such an effect, the monomer M3 is preferably used in combination with the monomer M2.

As the monomer M3, for example, among the (meth) acrylic monomers exemplified above, those in which the Tg of the homopolymer satisfies the condition can be used. For example, one or more monomers selected from the group consisting of (meth) acrylic acid alkyl esters can be used.

In the embodiment in which the monomer raw material B contains the monomer M3, the content of the monomer M3 may be, for example, 5% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight or more of the monomer raw material B. However, it may be 25% by weight or more, 30% by weight or more, or 35% by weight or more. Further, the content of the monomer M3 is usually preferably 70% by weight or less of the monomer raw material B, and may be 60% by weight or less, or 50% by weight or less. The content of the monomer M3 can be preferably applied, for example, in an embodiment in which the monomer M3 consists of one or more monomers selected from (meth) acrylic acid alkyl esters (eg, methacrylic acid alkyl esters).

In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the monomer raw material B preferably has a homopolymer Tg of more than 170 ° C. and a monomer content of 30% by weight or less. Here, the term "monomer content of X% by weight or less" in the present specification includes an embodiment in which the monomer content is 0% by weight, that is, an embodiment in which the monomer is substantially not contained, unless otherwise specified. It is a concept. Further, "substantially free" means that the above-mentioned monomer is not used at least intentionally. When the copolymerization ratio of the monomer having a Tg higher than 170 ° C. of the homopolymer is high, the mobility of the polymer B tends to be insufficient, and it becomes difficult to increase the adhesive strength by heating to a temperature range higher than 50 ° C. There can be.

In some embodiments, the monomer raw material B preferably contains at least MMA as the (meth) acrylic monomer. When MMA According to the copolymerized polymer B, a large pressure-sensitive adhesive sheet can be easily obtained in N _50. The ratio of MMA to the total amount of the (meth) acrylic monomer contained in the monomer raw material B may be, for example, 5% by weight or more, 10% by weight or more, 20% by weight or more, and 30% by weight or more. However, it may be 40% by weight or more. In some embodiments, the proportion of MMA in the total amount of the (meth) acrylic monomers may be, for example,> 50% by weight,> 55% by weight,> 60% by weight, or 65% by weight. It may be super or more than 70% by weight. The ratio of MMA to the total amount of the (meth) acrylic monomers is usually 95% by weight or less, 90% by weight or less, or 85% by weight or less. In some preferred embodiments, the proportion of MMA in the total amount of the (meth) acrylic monomers may be 75% by weight or less, 65% by weight or less, 60% or less, from the viewpoint of increasing the adhesive strength after mild heating. It may be 55% by weight or less (for example, 50% by weight or less).

As another example of the monomer that can be contained together with the monomer S1 as the monomer unit constituting the polymer B, the carboxyl group-containing monomer and the acid anhydride group-containing monomer exemplified above as the monomer that can be used when the polymer A is an acrylic polymer. Monomer, hydroxyl group-containing monomer, epoxy group-containing monomer, cyano group-containing monomer, isocyanate group-containing monomer, amide group-containing monomer, monomer having a nitrogen atom-containing ring (N-vinyl cyclic amide, monomer having a succinimide skeleton, maleimides, itaconimide) (Class, etc.), (meth) Acrylic acid aminoalkyls, vinyl esters, vinyl ethers, olefins, (meth) acrylic acid esters having aromatic hydrocarbon groups, heterocycle-containing (meth) acrylates, halogen atom-containing (meth) ) Acrylic, a (meth) acrylic acid ester obtained from a terpene compound derivative alcohol, and the like can be mentioned.

As yet another example of the monomer that can be contained together with the monomer S1 as the monomer unit constituting the polymer B, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di ( Oxyalkylene di (meth) acrylates such as meta) acrylates, propylene glycol di (meth) acrylates, dipropylene glycol di (meth) acrylates, tripropylene glycol di (meth) acrylates; monomers having a polyoxyalkylene skeleton, such as polyethylene glycol. It has a polymerizable functional group such as a (meth) acrylic acid group, a vinyl group, or an allyl group at one end of a polyoxyalkylene chain such as polypropylene glycol or polypropylene glycol, and an ether structure (alkyl ether, aryl ether, aryl alkyl) at the other end. Polymerizable polyoxyalkylene ether having (ether, etc.); methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxy (meth) acrylate (Meta) acrylic acid alkoxyalkyl such as propyl; salt such as (meth) acrylic acid alkali metal salt; polyvalent (meth) acrylate such as trimethyl propanthry (meth) acrylic acid ester: vinylidene chloride, (meth) acrylic acid Vinyl halide compounds such as -2-chloroethyl; oxazoline group-containing monomers such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline; (meth) acrylicoyl. Aziridine group-containing monomers such as aziridine, -2-aziridinylethyl (meth) acrylate; -2-hydroxyethyl (meth) acrylate, -2-hydroxypropyl (meth) acrylate, lactones and (meth) acrylic. A hydroxyl group-containing vinyl monomer such as an adduct with -2-hydroxyethyl acid; a fluorine-containing vinyl monomer such as a fluorine-substituted (meth) acrylic acid alkyl ester; a reactive halogen-containing vinyl monomer such as 2-chloroethyl vinyl ether and monochloroacrylic acid vinyl acetate. Organic silicon-containing vinyl such as vinyltrimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, allyltrimethoxysilane, trimethoxysilylpropylallylamine, 2-methoxyethoxytrimethoxysilane Lumonomer; In addition, macromonomers having a radically polymerizable vinyl group at the terminal of a monomer polymerized with a vinyl group; and the like can be mentioned. These can be copolymerized with the monomer S1 alone or in combination of two or more.

In some embodiments, the polymer B may preferably be one that does not have a functional group that causes a cross-linking reaction with the polymer A. In other words, the polymer B is preferably contained in the pressure-sensitive adhesive layer in a form that is not chemically bonded to the polymer A. The pressure-sensitive adhesive layer containing the polymer B in such a form has good mobility of the polymer B during heating and is suitable for improving the pressure-increasing ratio. The functional group that causes a cross-linking reaction with the polymer A may differ depending on the type of the functional group contained in the polymer A, and may be, for example, an epoxy group, an isocyanate group, a carboxy group, an alkoxysilyl group, an amino group, or the like.

The Mw of the polymer B is not particularly limited. The Mw of the polymer B may be, for example, 1000 or more, and may be 5000 or more. The Mw of the polymer B may be, for example, 10,000 or more, 12,000 or more, 15,000 or more, or 20,000 or more, from the viewpoint of preferably exhibiting an increase in adhesive strength after mild heating. In some embodiments, the Mw of Polymer B may be 50,000 or greater, 80,000 or higher, 100,000 or higher, or 120,000 or higher (eg, 150,000 or higher). The upper limit of Mw of the polymer B is, for example, 500,000 or less, may be 350,000 or less, may be 350,000 or less, or may be less than 100,000. The Mw of the polymer B may be less than 80,000 and less than 70,000 from the viewpoint of adjusting the compatibility and mobility in the pressure-sensitive adhesive layer to an appropriate range and preferably exhibiting an increase in the pressure-sensitive adhesive force after mild heating. It may be less than 50,000, less than 40,000, less than 20,000, and even less than 10,000.

In some preferred embodiments, the Mw of the polymer B is preferably lower than the Mw of the polymer A. This makes it easier to realize an adhesive sheet that achieves both good reworkability at the initial stage of application and an increase in adhesive strength after mild heating. The Mw of the polymer B may be, for example, 0.8 times or less of the Mw of the polymer A, 0.75 times or less, 0.5 times or less, 0.3 times or less, and 0.1. It may be double or less, 0.05 times or less, 0.03 times or less (for example, 0.02 times or less).

Polymer B can be produced, for example, by polymerizing the above-mentioned monomer by a known method such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, or a photopolymerization method.

Chain transfer agents can be used as needed to adjust the molecular weight of Polymer B. Examples of chain transfer agents used include compounds having a mercapto group such as octyl mercaptan, lauryl mercaptan, t-nonyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, α-thioglycerol; thioglycolic acid, methyl thioglycolate, etc. Ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, ethylene Thioglycolic acid esters such as thioglycolic acid ester of glycol, thioglycolic acid ester of neopentyl glycol, and thioglycolic acid ester of pentaerythritol; α-methylstyrene dimer; and the like can be mentioned.

The amount of the chain transfer agent used is not particularly limited, but is usually 0.05 parts by weight to 20 parts by weight, preferably 0.1 parts by weight to 15 parts by weight, based on 100 parts by weight of the monomer. , More preferably 0.2 parts by weight to 10 parts by weight. By adjusting the amount of the chain transfer agent added in this way, the polymer B having a suitable molecular weight can be obtained. Chain transfer agents can be used alone or in combination of two or more.

As a means for adjusting the molecular weight of the polymer B, various conventionally known means including the use of the chain transfer agent can be used alone or in combination as appropriate. The same applies to the molecular weight of polymer A. Non-limiting examples of such means include selection of polymerization method, selection of type and amount of polymerization initiator, selection of polymerization temperature, selection of type and amount of polymerization solvent in solution polymerization method, and light weight. Legal selection of light irradiation intensity, etc. are included. A person skilled in the art can understand how to obtain a polymer having a desired molecular weight based on the description of the present specification including the specific examples described later and the common general knowledge as of the filing of the present application.

In the pressure-sensitive adhesive sheet disclosed herein, the amount of polymer B used may be, for example, 0.1 part by weight or more with respect to 100 parts by weight of polymer A, and 0.5 part by weight from the viewpoint of obtaining a higher effect. It may be 1 part by weight or more, or 2 parts by weight or more. In some embodiments, from the viewpoint of improving reworkability, the amount of the polymer B used may be, for example, 3 parts by weight or more, 4 parts by weight or more, or 5 parts by weight or more. Further, the amount of polymer B used with respect to 100 parts by weight of polymer A may be, for example, 75 parts by weight or less, 60 parts by weight or less, or 50 parts by weight or less. From the viewpoint of avoiding an excessive decrease in the cohesive force of the pressure-sensitive adhesive layer, in some embodiments, the amount of the polymer B used with respect to 100 parts by weight of the polymer A can be, for example, 40 parts by weight or less, and 35 parts by weight or less. , 30 parts by weight or less, or 25 parts by weight or less. From the viewpoint of obtaining higher adhesive strength after heating, in some embodiments, the amount of the polymer B used may be 20 parts by weight or less, 17 parts by weight or less, 15 parts by weight or less, or 12 parts by weight. It may be 10 parts by weight or less, 8 parts by weight or less, 6 parts by weight or less, or 4 parts by weight or less (for example, 3 parts by weight or less).

The pressure-sensitive adhesive layer may contain a polymer (arbitrary polymer) other than the polymer A and the polymer B, if necessary, as long as the performance of the pressure-sensitive adhesive sheet disclosed herein is not significantly impaired. The amount of such arbitrary polymer used is usually 20% by weight or less of the total polymer component contained in the pressure-sensitive adhesive layer, and may be 15% by weight or less, or 10% by weight or less. In some embodiments, the amount of the optional polymer used may be 5% by weight or less of the total polymer component, 3% by weight or less, or 1% by weight or less. The pressure-sensitive adhesive layer may be substantially free of polymers other than Polymer A and Polymer B.

(Crosslinking agent)
A cross-linking agent may be used for the pressure-sensitive adhesive layer, if necessary, for the purpose of adjusting the cohesive force or the like. As the cross-linking agent, a cross-linking agent known in the field of adhesives can be used. Examples thereof include a cross-linking agent, an alkyl etherified melamine-based cross-linking agent, a metal chelate-based cross-linking agent, and the like. In particular, an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, and a metal chelate-based cross-linking agent can be preferably used. The cross-linking agent may be used alone or in combination of two or more.

Specifically, examples of isocyanate-based cross-linking agents include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, and naphthaline. Examples thereof include diisocyanates, triphenylmethane triisocyanates, polymethylene polyphenyl isocyanates, and adducts of these with polyols such as trimethylolpropane. Alternatively, a compound having at least one isocyanate group and one or more unsaturated bonds in one molecule, specifically, 2-isocyanatoethyl (meth) acrylate or the like may also be used as the isocyanate-based cross-linking agent. Can be done. These can be used alone or in combination of two or more.

Examples of the epoxy-based cross-linking agent include bisphenol A, epichlorohydrin-type epoxy-based resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, and trimethyl propanetri. Examples include glycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N', N'-tetraglycidyl-m-xylylenediamine and 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane. Can be done. These can be used alone or in combination of two or more.

Examples of the metal chelate compound include aluminum, iron, tin, titanium, nickel and the like as metal components, and acetylene, methyl acetoacetate, ethyl lactate and the like as chelate components. These can be used alone or in combination of two or more.

The amount used when the cross-linking agent is used is not particularly limited, and may be, for example, an amount exceeding 0 parts by weight with respect to 100 parts by weight of the polymer A. The amount of the cross-linking agent used can be, for example, 0.01 part by weight or more, preferably 0.05 part by weight or more, based on 100 parts by weight of the polymer A. As the amount of the cross-linking agent used increases, the adhesive strength at the initial stage of application is suppressed, and the reworkability tends to be improved. In some embodiments, the amount of the cross-linking agent used with respect to 100 parts by weight of the polymer A may be 0.1 parts by weight or more, 0.5 parts by weight or more, or 0.8 parts by weight or more. You may. On the other hand, from the viewpoint of appropriately allowing the mobility of the polymer B to obtain an increase in the adhesive strength after mild heating, it is usually appropriate that the amount of the cross-linking agent used with respect to 100 parts by weight of the polymer A is 15 parts by weight or less. It may be 10 parts by weight or less, or 5 parts by weight or less.

The technique disclosed herein can be preferably carried out in an embodiment in which at least an isocyanate-based cross-linking agent is used as the cross-linking agent. From the viewpoint of achieving both good reworkability at the initial stage of application and an increase in adhesive strength after mild heating, the amount of the isocyanate-based cross-linking agent used with respect to 100 parts by weight of the polymer A is, for example, 0.01 parts by weight or more in some embodiments. It may be 0.05 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more (for example, 0.3 parts by weight or more), or 5 parts by weight or less, for example. It may be 3 parts by weight or less, 1.5 parts by weight or less, 1.2 parts by weight or less, 0.8 parts by weight or less (for example, 0.6 parts by weight or less). May be good.

Although not particularly limited, if the pressure-sensitive adhesive layer is used isocyanate crosslinking agent in a configuration that includes a hydroxyl group-containing monomer as a monomer unit, the amount W _OH of the hydroxyl group-containing monomer to the amount W _NCO of isocyanate crosslinking agent, by _weight, it can be an amount that W OH _{/ W NCO} is 2 or more. By increasing the amount of the hydroxyl group-containing monomer used for the isocyanate-based cross-linking agent in this way, a cross-linked structure suitable for greatly increasing the adhesive force after mild heating with respect to the adhesive force at the initial stage of application can be formed. In some embodiments, the _WOH / W _NCO may be 3 or greater, 5 or greater, 10 or greater, 20 or greater, or 30 or greater. It may be 50 or more. The upper limit of W _OH / W _{NCO is not particularly limited, and the W OH} / W _NCO may be, for example, 500 or less, and 200 or less, from the viewpoint of the degree of cross-linking that allows appropriate movement of the polymer B by mild heating. It may be 100 or less, or 50 or less.

A cross-linking catalyst may be used to more effectively proceed with any of the above-mentioned cross-linking reactions. As the cross-linking catalyst, for example, a tin-based catalyst (particularly dioctyltin dilaurate) can be preferably used. The amount of the cross-linking catalyst used is not particularly limited, but can be, for example, approximately 0.0001 parts by weight to 1 part by weight with respect to 100 parts by weight of the polymer A.

A polyfunctional monomer may be used for the pressure-sensitive adhesive layer, if necessary. The polyfunctional monomer can be useful for purposes such as adjusting the cohesive force by being used in place of the above-mentioned cross-linking agent or in combination with the cross-linking agent. For example, a polyfunctional monomer may be preferably used in a pressure-sensitive adhesive layer formed from a photocurable pressure-sensitive adhesive composition.
Examples of the polyfunctional monomer include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, and neopentyl glycol di (meth) acrylate. Pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,12-dodecane Didioldi (meth) acrylate, trimethylolpropantri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl Examples thereof include diol (meth) acrylate and hexyldiol di (meth) acrylate. Of these, trimethylolpropane tri (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and dipentaerythritol hexa (meth) acrylate can be preferably used. The polyfunctional monomer can be used alone or in combination of two or more.

The amount of the polyfunctional monomer used varies depending on its molecular weight, the number of functional groups, and the like, but it is usually appropriate to use it in the range of 0.01 parts by weight to 3.0 parts by weight with respect to 100 parts by weight of the polymer A. .. In some embodiments, the amount of the polyfunctional monomer used may be, for example, 0.02 parts by weight or more, or 0.03 parts by weight or more, based on 100 parts by weight of the polymer A. As the amount of the polyfunctional monomer used increases, the adhesive strength at the initial stage of application is suppressed, and the reworkability tends to be improved. On the other hand, from the viewpoint of ensuring the mobility of the polymer B and controlling the movement with a cross-linking network to control the increase in the adhesive strength after mild heating, the amount of the polyfunctional monomer used is 100 parts by weight of the polymer A. It may be 2.0 parts by weight or less, 1.0 part by weight or less, or 0.5 part by weight or less.

(Adhesive-imparting resin)
The pressure-sensitive adhesive layer may contain a pressure-sensitive adhesive resin, if necessary. The tackifier resin is not particularly limited, but for example, a rosin-based tackifier resin, a terpene-based tackifier resin, a phenol-based tackifier resin, a hydrocarbon-based tackifier resin, a ketone-based tackifier resin, a polyamide-based tackifier resin, etc. Examples thereof include an epoxy-based adhesive-imparting resin and an elastomer-based adhesive-imparting resin. The tackifier resin may be used alone or in combination of two or more.

Examples of the rosin-based tackifier resin include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin, and modified rosins obtained by polymerizing, disproportionating, or hydrogenating these unmodified rosins. Polymerized rosins, stabilized rosins, disproportionated rosins, fully hydrogenated rosins, partially hydrogenated rosins and other chemically modified rosins), as well as various rosin derivatives.
Examples of the rosin derivative include
A rosin phenol-based resin obtained by adding phenol to rosins (unmodified rosin, modified rosin, various rosin derivatives, etc.) with an acid catalyst and thermally polymerizing them;
Alcohols are ester compounds of rosin obtained by esterifying unmodified rosin with alcohols (unmodified rosin ester), and modified rosins such as polymerized rosin, stabilized rosin, disproportionated rosin, fully hydrogenated rosin, and partially hydrogenated rosin. Resin ester-based resins such as ester compounds of modified rosins esterified with (polymerized rosin ester, stabilized rosin ester, disproportionated rosin ester, fully hydrogenated rosin ester, partially hydrogenated rosin ester, etc.);
Unsaturated fatty acid-modified rosin-based resin obtained by modifying unmodified rosin or modified rosin (polymerized rosin, stabilized rosin, disproportionated rosin, fully hydrogenated rosin, partially hydrogenated rosin, etc.) with unsaturated fatty acids;
Unsaturated fatty acid-modified rosin ester-based resin obtained by modifying rosin ester-based resin with unsaturated fatty acid;
Carboxyl group in unmodified rosin, modified rosin (polymerized rosin, stabilized rosin, disproportionated rosin, fully hydrogenated rosin, partially hydrogenated rosin, etc.), unsaturated fatty acid modified rosin resin and unsaturated fatty acid modified rosin ester resin. Rosin alcohol-based resin treated with reduction;
Examples thereof include unmodified rosin, modified rosin, and metal salts of rosin-based resins (particularly rosin ester-based resins) such as various rosin derivatives.

Examples of the terpene-based tackifier resin include terpene-based resins such as α-pinene polymer, β-pinene polymer, and dipentene polymer, and modification of these terpene-based resins (phenol modification, aromatic modification, and hydrocarbon modification). , Hydrocarbon-modified, etc.) modified terpene-based resin (for example, terpene phenol-based resin, styrene-modified terpene-based resin, aromatic-modified terpene-based resin, hydrogenated terpene-based resin, etc.) and the like.

Examples of the phenol-based tackifier resin include a condensate of various phenols (eg, phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcin, etc.) and formaldehyde (eg, alkylphenol-based resin, xyleneformaldehyde). Examples thereof include resole obtained by adding and reacting the above-mentioned phenols and formaldehyde with an alkali catalyst, and novolak obtained by conducting a condensation reaction between the above-mentioned phenols and formaldehyde with an acid catalyst.

Examples of hydrocarbon-based tackifier resins include aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic / aromatic petroleum resins (styrene-olefin copolymers, etc.). ), Various hydrocarbon-based resins such as aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, kumaron-based resins, and kumaron-inden-based resins.

Commercially available products of the polymerized rosin ester that can be preferably used include the trade names "Pencel D-125", "Pencel D-135", "Pencel D-160", "Pencel KK", and "Pencel" manufactured by Arakawa Chemical Industry Co., Ltd. "C" and the like are exemplified, but the present invention is not limited to these.

Commercially available terpene phenolic resins that can be preferably used include the trade names "YS Polystar S-145", "YS Polystar G-125", "YS Polystar N125", and "YS Polystar U-115" manufactured by Yasuhara Chemical Co., Ltd. , Product names "Tamanor 803L" and "Tamanor 901" manufactured by Arakawa Chemical Industry Co., Ltd., and product names "Sumilite Resin PR-12603" manufactured by Sumitomo Bakelite Co., Ltd. are exemplified, but not limited thereto.

The content of the tackifier resin is not particularly limited, and can be set so as to exhibit appropriate tackling performance according to the purpose and application. The content of the tackifier resin with respect to 100 parts by weight of the polymer A (when two or more kinds of tackifier resins are included, the total amount thereof) can be, for example, about 5 to 500 parts by weight.

As the tackifier resin, a resin having a softening point (softening temperature) of about 80 ° C. or higher (preferably about 100 ° C. or higher, for example, about 120 ° C. or higher) can be preferably used. According to the pressure-sensitive adhesive resin having a softening point equal to or higher than the above-mentioned lower limit, it is easy to obtain a pressure-sensitive adhesive sheet having a high pressure-sensitive adhesive force after heating. The upper limit of the softening point is not particularly limited, and may be, for example, about 200 ° C. or lower (typically 180 ° C. or lower). The softening point of the tackifier resin can be measured based on the softening point test method (ring ball method) specified in JIS K2207.

In addition, the pressure-sensitive adhesive layer in the technique disclosed herein is a leveling agent, a plasticizer, a softening agent, a colorant (dye, pigment, etc.), a filler, and an antistatic agent to the extent that the effect of the present invention is not significantly impaired. , Antioxidants, UV absorbers, Antioxidants, Light Stabilizers, Preservatives, and other known additives that can be used in adhesives may be included, if necessary.

The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet disclosed herein can be a cured layer of the pressure-sensitive adhesive composition. That is, the pressure-sensitive adhesive layer is formed by applying (for example, coating) a pressure-sensitive adhesive composition such as a water-dispersed type, a solvent type, a photo-curing type, or a hot-melt type to an appropriate surface, and then appropriately performing a curing treatment. obtain. When performing two or more types of curing treatments (drying, crosslinking, polymerization, cooling, etc.), these can be performed simultaneously or in multiple steps. In a pressure-sensitive adhesive composition using a partial polymer (polymer syrup) of a monomer raw material, a final copolymerization reaction is typically performed as the above-mentioned curing treatment. That is, the partial polymer is subjected to a further copolymerization reaction to form a complete polymer. For example, in the case of a photocurable pressure-sensitive adhesive composition, light irradiation is performed. If necessary, hardening treatment such as crosslinking and drying may be carried out. For example, when it is necessary to dry with a photocurable pressure-sensitive adhesive composition, it is preferable to perform photo-curing after drying. In the pressure-sensitive adhesive composition using a complete polymer, typically, as the above-mentioned curing treatment, treatments such as drying (heat drying) and cross-linking are carried out as necessary.

The application of the pressure-sensitive adhesive composition can be carried out using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater.

The thickness of the pressure-sensitive adhesive layer is not particularly limited and may be, for example, 1 μm or more. In some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 3 μm or more, 5 μm or more, 8 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, or 20 μm or more. As the thickness of the pressure-sensitive adhesive layer increases, the pressure-sensitive adhesive force tends to increase after heating. Further, in some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 40 μm or less. It may be as follows. The fact that the thickness of the pressure-sensitive adhesive layer is not too large can be advantageous from the viewpoints of thinning the pressure-sensitive adhesive sheet and preventing cohesive failure of the pressure-sensitive adhesive layer. In the case of a pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer on the first and second surfaces of the base material, the thickness of the above-mentioned pressure-sensitive adhesive layer is at least the thickness of the first pressure-sensitive adhesive layer. Can be applied to. The thickness of the second pressure-sensitive adhesive layer may be selected from the same range. Further, in the case of a base material-less pressure-sensitive adhesive sheet, the thickness of the pressure-sensitive adhesive sheet matches the thickness of the pressure-sensitive adhesive layer.

The storage elastic modulus G'(150 ° C.) of the pressure-sensitive adhesive layer at 150 ° C. is appropriately set within a range in which the adhesive strength increases to a predetermined value or more after mild heating, and is not limited to a specific range. In some embodiments, the storage elastic modulus G'(150 ° C.) of the pressure-sensitive adhesive layer can be 5000 Pa or more, and is preferably 10,000 Pa from the viewpoint of obtaining good pressure-sensitive properties such as low adhesive strength at the initial stage of application. As described above, it is more preferably 15,000 Pa or more, further preferably 20,000 Pa or more (for example, 25,000 Pa or more), 30,000 Pa or more, 40,000 Pa or more, or 50,000 Pa or more. The storage elastic modulus G'(150 ° C.) can be, for example, 300,000 Pa or less, 200,000 Pa or less, 150,000 Pa or less, or 100,000 Pa or less. In some preferred embodiments, the storage modulus G'(150 ° C.) suitably increases the adhesive strength after mild heating as a degree of cross-linking that allows moderate movement of the polymer B in the adhesive layer. , 90,000 Pa or less, 70,000 Pa or less, 50,000 Pa or less, 40,000 Pa or less, or 30,000 Pa or less. The storage elastic modulus G'(150 ° C.) of the pressure-sensitive adhesive layer can be adjusted by the type and amount of the cross-linking agent, the molecular weight of the polymer A, the molecular structure and the like. The storage elastic modulus G'(150 ° C.) of the pressure-sensitive adhesive layer is measured by the method described in Examples described later.

Although not particularly limited, the gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is usually preferably in the range of 20.0% to 99.0%, and is 30.0% to 90. It is desirable to be in the range of 0%. By setting the gel fraction within the above range, it is possible to suitably realize an increase in adhesive strength after mild heating. The gel fraction is measured by the following method.

[Measurement of gel fraction]
A pressure-sensitive adhesive sample (weight Wg _{1 ) of about 0.1 g is wrapped in a purse-like shape with a porous polytetrafluoroethylene film (weight Wg 2} ) having an average pore diameter of 0.2 μm, and the mouth is tied with octopus thread (weight Wg ₃ ). As the porous polytetrafluoroethylene membrane, trade name "Nitoflon (registered trademark) NTF1122" (Nitto Denko Corporation, average pore diameter 0.2 μm, porosity 75%, thickness 85 μm) or an equivalent product thereof is used. This package is immersed in 50 mL of ethyl acetate and held at room temperature (typically 23 ° C.) for 7 days to elute the sol component (ethyl acetate-soluble component) in the pressure-sensitive adhesive out of the membrane. Then, the package is taken out, the ethyl acetate adhering to the outer surface is wiped off, the package is dried at 130 ° C. for 2 hours, and the weight of the package (Wg ₄ ) is measured. By substituting each value into the following equation, it is possible to calculate the gel fraction G _C of the pressure-sensitive adhesive.
Gel fraction _{G C (%) = [(} Wg 4 -Wg 2 -Wg 3) / Wg 1] × 100

<Supporting base material>
The pressure-sensitive adhesive sheet according to some embodiments may be in the form of a base-attached pressure-sensitive adhesive sheet having an pressure-sensitive adhesive layer on one or both sides of a supporting base material. The material of the supporting base material is not particularly limited, and can be appropriately selected depending on the purpose of use, the mode of use, and the like of the pressure-sensitive adhesive sheet. Non-limiting examples of the base material that can be used include a polyolefin film containing a polyolefin such as polypropylene or an ethylene-propylene copolymer as a main component, a polyester film containing a polyester such as polyethylene terephthalate or polybutylene terephthalate as a main component, and a polyester film containing polyester as a main component. Plastic film such as polyvinyl chloride film containing polyvinyl chloride as the main component; foam sheet made of foam such as polyurethane foam, polyethylene foam, polychloroprene foam; various fibrous substances (natural fibers such as hemp and cotton, Woven fabrics and non-woven fabrics made of synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, etc.) alone or by blending; papers such as Japanese paper, high-quality paper, kraft paper, crepe paper; aluminum foil, Metallic foil such as copper foil; and the like. A base material having a composite structure thereof may be used. Examples of such a composite base material include a base material having a structure in which a metal foil and the above plastic film are laminated, a plastic base material reinforced with an inorganic fiber such as glass cloth, and the like.

As the base material of the pressure-sensitive adhesive sheet disclosed herein, various film base materials can be preferably used. The film base material may be a porous base material such as a foam film or a non-woven fabric sheet, or may be a non-porous base material, and may be a porous layer and a non-porous layer. It may be a base material having a laminated structure. In some embodiments, as the film substrate, a film containing an independently shape-maintainable (self-supporting or independent) resin film as a base film can be preferably used. As used herein, the term "resin film" means a resin film (of voidless) having a non-porous structure and typically containing substantially no bubbles. Therefore, the resin film is a concept that is distinguished from foam films and non-woven fabrics. As the resin film, one that can independently maintain its shape (self-supporting or independent) can be preferably used. The resin film may have a single-layer structure or a multi-layer structure having two or more layers (for example, a three-layer structure).

Examples of the resin material constituting the resin film include polyamide (PA) such as polyester, polyolefin, nylon 6, nylon 66, and partially aromatic polyamide, polyimide (PI), polyamideimide (PAI), and polyether ether ketone (PEEK). ), Polyether sulfone (PES), Polyphenylene sulfide (PPS), Polycarbonate (PC), Polyurethane (PU), Ethylene-vinyl acetate copolymer (EVA), Polytetrafluoroethylene (PTFE) and other fluororesins and acrylic resins. , Polyacrylate, Polyamide, Polyvinyl Chloride, Polyvinylidene Chloride and the like can be used. The resin film may be formed by using a resin material containing one kind of such a resin alone, or may be formed by using a resin material in which two or more kinds are blended. good. The resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).

Preferable examples of the resin material constituting the resin film include polyester-based resin, PPS resin, and polyolefin-based resin. Here, the polyester-based resin refers to a resin containing polyester in a proportion of more than 50% by weight. Similarly, the PPS resin refers to a resin containing PPS in a proportion of more than 50% by weight, and the polyolefin-based resin refers to a resin containing polyolefin in a proportion of more than 50% by weight.

As the polyester-based resin, a polyester-based resin containing polyester as a main component, which is obtained by polycondensing a dicarboxylic acid and a diol, is typically used.

Examples of the dicarboxylic acid constituting the polyester include phthalic acid, isophthalic acid, terephthalic acid, 2-methylterephthalic acid, 5-sulfoisophthalic acid, 4,4'-diphenyldicarboxylic acid, and 4,4'-diphenyletherdicarboxylic acid. , 4,4'-Diphenylketonedicarboxylic acid, 4,4'-diphenoxyetanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2, Aromatic dicarboxylic acids such as 6-naphthalenedicarboxylic acid and 2,7-naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. An aliphatic dicarboxylic acid such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, dodecanoic acid; unsaturated dicarboxylic acid such as maleic acid, maleic anhydride, fumaric acid; Examples thereof include these derivatives (for example, lower alkyl esters of the above dicarboxylic acids such as terephthalic acid); and the like. These can be used alone or in combination of two or more. Aromatic dicarboxylic acids are preferable from the viewpoint of strength and the like. Among them, preferred dicarboxylic acids include terephthalic acid and 2,6-naphthalenedicarboxylic acid. For example, 50% by weight or more (for example, 80% by weight or more, typically 95% by weight or more) of the dicarboxylic acids constituting the polyester is terephthalic acid, 2,6-naphthalenedicarboxylic acid or a combination thereof. Is preferable. The dicarboxylic acid may be composed of substantially only terephthalic acid, substantially only 2,6-naphthalenedicarboxylic acid, or substantially only terephthalic acid and 2,6-naphthalenedicarboxylic acid.

Examples of the diol constituting the polyester include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,5-pentanediol, neopentyl glycol, and 1,4-butanediol. Aliphatic diols such as 1,6-hexanediol, 1,8-octanediol, polyoxytetramethylene glycol; 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4 -Alicyclic diols such as cyclohexanedimethylol, aromatic diols such as xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis (4'-hydroxyphenyl) propane, and bis (4-hydroxyphenyl) sulfone. ; Etc. can be mentioned. These can be used alone or in combination of two or more. Of these, aliphatic diols are preferable from the viewpoint of transparency and the like, and ethylene glycol is particularly preferable. The ratio of the aliphatic diol (preferably ethylene glycol) to the diol constituting the polyester is preferably 50% by weight or more (for example, 80% by weight or more, typically 95% by weight or more). The diol may be composed substantially only of ethylene glycol.

Specific examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate and the like.

As the polyolefin resin, one kind of polyolefin can be used alone, or two or more kinds of polyolefins can be used in combination. The polyolefin can be, for example, a homopolymer of an α-olefin, a copolymer of two or more kinds of α-olefins, a copolymer of one or more kinds of α-olefins and another vinyl monomer, and the like. Specific examples include ethylene-propylene copolymers such as polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, and ethylene propylene rubber (EPR), and ethylene-propylene-. Examples thereof include a butene copolymer, an ethylene-butene copolymer, an ethylene-vinyl alcohol copolymer, and an ethylene-ethyl acrylate copolymer. Both low density (LD) polyolefins and high density (HD) polyolefins can be used. Examples of polyolefin resin films include unstretched polypropylene (CPP) film, biaxially stretched polypropylene (OPP) film, low density polyethylene (LDPE) film, linear low density polyethylene (LLDPE) film, medium density polyethylene (MDPE). Examples thereof include a film, a high-density polyethylene (HDPE) film, a polyethylene (PE) film in which two or more types of polyethylene (PE) are blended, and a PP / PE blend film in which polypropylene (PP) and polyethylene (PE) are blended.

Specific examples of the resin film that can be preferably used as the base film of the pressure-sensitive adhesive sheet disclosed herein include PET film, PEN film, PPS film, PEEK film, CPP film and OPP film. Examples of preferable base films from the viewpoint of strength and dimensional stability include PET film, PEN film, PPS film and PEEK film. PET film and PPS film are particularly preferable from the viewpoint of easy availability of the base material, and PET film is particularly preferable.

Known resin films include light stabilizers, antioxidants, antistatic agents, colorants (dyees, pigments, etc.), fillers, slip agents, antiblocking agents, etc., as long as the effects of the present invention are not significantly impaired. Additives can be added as needed. The blending amount of the additive is not particularly limited, and can be appropriately set according to the use of the pressure-sensitive adhesive sheet and the like.

The method for producing the resin film is not particularly limited. For example, conventionally known general resin film molding methods such as extrusion molding, inflation molding, T-die casting molding, and calender roll molding can be appropriately adopted.

The substrate may be substantially composed of such a base film. Alternatively, the base material may include an auxiliary layer in addition to the base film. Examples of the auxiliary layer include an optical property adjusting layer (for example, a colored layer and an antireflection layer), a printing layer or a laminating layer for imparting a desired appearance to a substrate, an antistatic layer, an undercoat layer, and a peeling layer. Such as a surface treatment layer.

The thickness of the base material is not particularly limited, and can be selected according to the purpose of use, the mode of use, and the like of the pressure-sensitive adhesive sheet. The thickness of the substrate can be, for example, 1000 μm or less. In some embodiments, the thickness of the substrate may be, for example, 500 μm or less, 300 μm or less, 250 μm or less, or 200 μm from the viewpoint of handleability and processability of the pressure-sensitive adhesive sheet. It may be as follows. From the viewpoint of miniaturization and weight reduction of the product to which the pressure-sensitive adhesive sheet is applied, in some embodiments, the thickness of the base material may be, for example, 160 μm or less, 130 μm or less, or 100 μm or less. It may be 90 μm or less, 80 μm or less, 60 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, or 5 μm or less. As the thickness of the base material becomes smaller, the flexibility of the adhesive sheet and the followability to the surface shape of the adherend tend to improve. Further, from the viewpoint of handleability, processability and the like, the thickness of the base material may be, for example, 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 25 μm or more, or 25 μm or more. In some embodiments, the thickness of the substrate may be, for example, 30 μm or more, 35 μm or more, 55 μm or more, 70 μm or more, 75 μm or more, 90 μm or more, 120 μm or more. .. For example, in an adhesive sheet that can be used for the purpose of reinforcing, supporting, impact mitigating, or the like of an adherend, a base material having a thickness of 30 μm or more can be preferably adopted.

The first surface of the base material is a conventionally known surface such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and formation of an undercoat layer by applying an undercoat agent (primer), if necessary. It may be treated. Such a surface treatment may be a treatment for improving the anchoring property of the pressure-sensitive adhesive layer on the substrate. For example, in an adhesive sheet provided with a base material containing a resin film as a base film, a base material subjected to such anchoring property improving treatment can be preferably adopted. The above surface treatments can be applied alone or in combination. The composition of the primer used for forming the undercoat layer is not particularly limited, and can be appropriately selected from known ones. The thickness of the undercoat layer is not particularly limited, but is usually about 0.01 μm to 1 μm, preferably about 0.1 μm to 1 μm. Other treatments that can be applied to the first surface of the substrate as needed include antistatic layer forming treatments, colored layer forming treatments, printing treatments and the like.

When the pressure-sensitive adhesive sheet disclosed herein is in the form of a single-sided pressure-sensitive adhesive sheet having an adhesive layer only on the first surface of the base material, the second side surface of the base material is subjected to a peeling treatment or an antistatic treatment, if necessary. Such as, conventionally known surface treatment may be applied. For example, by surface-treating the back surface of the base material with a release treatment agent (typically, by providing a release layer with a release treatment agent), the rewinding force of the adhesive sheet in the form of being wound in a roll shape can be obtained. Can be lightened. As the stripping agent, a silicone-based stripping agent, a long-chain alkyl-based stripping agent, an olefin-based stripping agent, a fluorine-based stripping agent, a fatty acid amide-based stripping agent, molybdenum sulfide, silica powder, or the like can be used. .. In addition, for the purpose of improving printability, reducing light reflectivity, improving stackability, etc., the second surface of the base material is subjected to treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, and alkali treatment. It may have been done. Further, in the case of the double-sided adhesive sheet, the second surface of the base material is subjected to the same surface treatment as those exemplified above as the surface treatment that can be applied to the first surface of the base material, if necessary. May be good. The surface treatment applied to the first surface of the base material and the surface treatment applied to the second surface may be the same or different.

<Adhesive sheet>
(Characteristics of adhesive sheet, etc.)
The PSA sheet disclosed herein may be indicative of adhesion, measured at 23 ° C. After holding 5N / 25 mm or more adhesion N _50, i.e. bonded to a stainless steel plate 50 ° C. for 15 minutes. After the adhesive sheet satisfying this characteristic is attached to the adherend, the adhesive strength is increased to a predetermined value or more by mild heating at about 50 ° C. According to the technique disclosed here, since it is possible to obtain a strong adhesive force by mild heating, the adhesive force N ₅₀ can be set to 7 N / 25 mm or more, for example, 10 N / 25 mm or more, and further 13 N. It can be / 25 mm or more, 15N / 25 mm or more, 17N / 25 mm or more, 19N / 25 mm or more, 21N / 25 mm or more, 23N / 25 mm or more (for example, 25N / 25 mm or more). The upper limit of the adhesive strength N _{50 is not particularly limited.} From the viewpoint of ease of manufacturing and economic efficiency of the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive force N ₅₀ may be, for example, 70 N / 25 mm or less, 50 N / 25 mm or less, or 40 N / 25 mm or less in some embodiments.

_{The adhesive force N 23} measured after being bonded to a stainless steel plate and held at 23 ° C. for 30 minutes is not particularly limited, and in some embodiments, the adhesive force N ₂₃ may be, for example, 3N / 25 mm or less. It is preferably 2.5 N / 25 mm or less, more preferably less than 2 N / 25 mm, and may be 1.5 N / 25 mm or less, 1.2 N / 25 mm or less, or 1 N / 25 mm or less. A low adhesive force N ₂₃ is preferable from the viewpoint of reworkability. The lower limit of the adhesive force N ₂₃ is not particularly limited, and for example. It can be 0.01 N / 25 mm or more. _{The adhesive strength N 23} is usually preferably 0.1 N / 25 mm or more from the viewpoint of sticking workability to the adherend and prevention of positional deviation before the adhesive strength increases. From the viewpoint of improving the adhesive strength after heating, in some embodiments, the adhesive strength N ₂₃ may be, for example, 0.2 N / 25 mm or more, 0.5 N / 25 mm or more, and 0.8 N / 25 mm or more. It may be 1.0 N / 25 mm or more (for example, 1.5 N / 25 mm or more).

_{The adhesive force N 80} measured at 23 ° C. after being bonded to a stainless steel plate and held at 80 ° C. for 5 minutes is not particularly limited, and in some embodiments, the adhesive force N ₈₀ is, for example, 5 N / 25 mm or more. It may be 7N / 25mm or more, 10N / 25mm or more, 13N / 25mm or more, 15N / 25mm or more, 17N / 25mm or more, 20N / 25mm or more, 25N / 25mm or more. It may be 30N / 25mm or more (for example, 35N / 25mm or more). Further, from the viewpoint of ease of manufacturing and economic efficiency of the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive force N ₈₀ may be, for example, 70 N / 25 mm or less, 50 N / 25 mm or less, or 40 N / 25 mm or less in some embodiments. ..

_{The ratio of the adhesive force N 50} [N / 25 mm] to the adhesive force N ₂₃ [N / 25 mm], that is, the adhesive force increase ratio N ₅₀ / N ₂₃ is not particularly limited, and in some embodiments, the N ₅₀ / N _23. Is 2 or more (for example, 3 or more), preferably 5 or more, more preferably 8 or more, 10 or more, 12 or more, 15 or more, and 18 or more. , 20 or more may be used. According to the pressure-sensitive adhesive sheet having a large N ₅₀ / N ₂₃ , good reworkability is exhibited at the initial stage of pasting, and the adhesive strength can be greatly increased by subsequent heating or the like. The upper limit of N ₅₀ / N ₂₃ is not particularly limited, and is usually 100 or less, 80 or less, 60 or less, 50 or less, which is typical from the viewpoint of ease of manufacturing and economic efficiency of the adhesive sheet. Is 30 or less, and may be 20 or less. In some embodiments, N ₅₀ / N ₂₃ may be, for example, 18 or less, 15 or less, or 12 or less.

The ratio of the adhesive strength _N 80 _[N / 25mm] for adhesion _N 50 _[N / 25mm], i.e. the adhesive force increase ratio _N 80 _{/ N 50} is not particularly limited, in some _embodiments, N 80 _{/ N 50} Is preferably 3 or less, preferably 2 or less, for example 1.8 or less, or 1.5 or less (for example, 1.3 or less). According to the adhesive sheet satisfying this characteristic, the adhesive strength can be sufficiently increased by mild heating of about 50 ° C., and further high temperature (specifically, heating of about 80 ° C.) is obtained in order to obtain the desired adhesive strength. No need to expose to. The lower limit of N ₈₀ / N ₅₀ is not particularly limited, and in some embodiments, for example, it may be 1 or more, 1.2 or more, or 1.4 or more from the viewpoint of ease of manufacturing and economic efficiency of the pressure-sensitive adhesive sheet. It may be 1.6 or more.

Here, the adhesive strength N ₂₃ [N / 25 mm] is pressure-bonded to a stainless steel (SUS) plate as an adherend and left in an environment of 23 ° C. and 50% RH for 30 minutes, and then in the same environment (that is, that is). (At 23 ° C.), the peeling angle is 180 degrees, and the tensile speed is 300 mm / min.
The adhesive strength N ₅₀ [N / 25 mm] is pressure-bonded to a SUS plate as an adherend and held in an environment of 50 ° C. for 15 minutes, and then left in an environment of 23 ° C. and 50% RH for 30 minutes, and then in the same environment. In, 180 ° peeling adhesive force is measured under the conditions of a peeling angle of 180 degrees and a tensile speed of 300 mm / min.
The adhesive strength N ₈₀ [N / 25 mm] is applied by crimping to a SUS plate as an adherend, heating at 80 ° C. for 5 minutes, and then leaving it in an environment of 23 ° C. and 50% RH for 30 minutes, and then in the same environment. It is grasped by measuring the peeling adhesive force by 180 ° under the conditions of a peeling angle of 180 degrees and a tensile speed of 300 mm / min.
As the adherend, a SUS304BA plate is used in any of the measurements of the adhesive strengths N ₂₃ , N ₅₀ , and N _80. In the measurement, if necessary, an appropriate backing material (for example, a PET film having a thickness of about 25 μm) can be attached to the pressure-sensitive adhesive sheet to be measured to reinforce it. The adhesive strengths N ₂₃ , N ₅₀ , and N ₈₀ can be measured more specifically according to the method described in Examples described later.

The heat-sensitive adhesive force of the pressure-sensitive adhesive sheet disclosed herein represents one characteristic of the pressure-sensitive adhesive sheet, and does not limit the usage mode of the pressure-sensitive adhesive sheet. In other words, the mode of use of the pressure-sensitive adhesive sheet disclosed herein is not limited to the mode of heating at 50 ° C. for 15 minutes, for example, in the room temperature range (usually 20 ° C. to 30 ° C., typically 23 ° C. to 25 ° C.). It can also be used in a mode in which the treatment of heating above ° C.) is not particularly performed. Even in such a usage mode, the adhesive strength is increased in a long period of time, and a strong bond can be realized. Further, the pressure-sensitive adhesive sheet disclosed herein can promote an increase in adhesive strength by performing a heat treatment at an arbitrary timing after sticking at a temperature higher than 30 ° C. (for example, 50 ° C.) or 50 ° C. The heating temperature in such a heat treatment is not particularly limited, and can be set in consideration of workability, economy, heat resistance of the base material of the pressure-sensitive adhesive sheet, the heat resistance of the adherend, and the like. The heating temperature may be, for example, less than 150 ° C., 120 ° C. or lower, 100 ° C. or lower, 80 ° C. or lower, or 70 ° C. or lower. The heating temperature can be, for example, 40 ° C. or higher, 45 ° C. or higher, 50 ° C. or higher, 55 ° C. or higher, 60 ° C. or higher, or 70 ° C. or higher, 80 ° C. or higher, or 100 ° C. or higher. good. The heating time is not particularly limited, and may be, for example, 1 hour or less, 30 minutes or less, 10 minutes or less, or 5 minutes or less. The heating time may be, for example, 1 minute or longer, 3 minutes or longer, 7 minutes or longer, or 15 minutes or longer. Alternatively, the heat treatment may be performed for a longer period of time as long as the pressure-sensitive adhesive sheet or the adherend is not significantly deteriorated by heat. The heat treatment may be performed at one time or may be performed in a plurality of times.

(Adhesive sheet with base material)
When the pressure-sensitive adhesive sheet disclosed herein is in the form of a pressure-sensitive adhesive sheet with a base material, the thickness of the pressure-sensitive adhesive sheet may be, for example, 1000 μm or less, 600 μm or less, 350 μm or less, 250 μm or less. But it may be. From the viewpoint of miniaturization, weight reduction, thinning, and the like of the product to which the pressure-sensitive adhesive sheet is applied, the thickness of the pressure-sensitive adhesive sheet may be, for example, 200 μm or less, or 175 μm or less, in some embodiments. It may be 140 μm or less, 120 μm or less, or 100 μm or less (for example, less than 100 μm). Further, from the viewpoint of handleability and the like, the thickness of the pressure-sensitive adhesive sheet may be, for example, 5 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, or 30 μm or more. In some embodiments, the thickness of the pressure-sensitive adhesive sheet may be, for example, 50 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, or 120 μm or more. The upper limit of the thickness of the adhesive sheet is not particularly limited.
The thickness of the adhesive sheet means the thickness of the portion to be attached to the adherend. For example, in the pressure-sensitive adhesive sheet 1 having the configuration shown in FIG. 1, it refers to the thickness from the pressure-sensitive adhesive surface 21A of the pressure-sensitive adhesive sheet 1 to the second surface 10B of the base material 10, and does not include the thickness of the release liner 31.

The pressure-sensitive adhesive sheet disclosed herein may be suitably implemented, for example, in an embodiment in which the thickness Ts of the supporting base material is larger than the thickness Ta of the pressure-sensitive adhesive layer, that is, the Ts / Ta is larger than 1. Although not particularly limited, Ts / Ta may be, for example, 1.1 or more, 1.2 or more, 1.5 or more, or 1.7 or more. May be good. For example, in an adhesive sheet that can be used for the purpose of reinforcing, supporting, impact mitigating, or the like of an adherend, an increase in Ts / Ta tends to make it easier for a good effect to be exhibited even if the adhesive sheet is made thinner. In some embodiments, Ts / Ta may be 2 or greater (eg, greater than 2), 2.5 or greater, or 2.8 or greater. Further, Ts / Ta may be, for example, 50 or less, or 20 or less. The Ts / Ta may be, for example, 10 or less, 8 or less, or 5 or less, from the viewpoint of facilitating the high adhesive force after heating even if the pressure-sensitive adhesive sheet is made thin.

The pressure-sensitive adhesive layer is preferably adhered to the supporting base material. Here, "sticking" means that in an adhesive sheet whose adhesive strength has increased after being attached to an adherend, the adhesive layer does not peel off at the interface between the adhesive layer and the supporting base material when the adhesive sheet is peeled off from the adherend. In addition, it means that the pressure-sensitive adhesive layer exhibits sufficient anchoring property with respect to the supporting base material. According to the pressure-sensitive adhesive sheet with a base material in which the pressure-sensitive adhesive layer is fixed to the support base material, the adherend and the support base material can be firmly integrated. As a preferable example of the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is adhered to the base material, the pressure-sensitive adhesive does not cause peeling (anchor destruction) between the pressure-sensitive adhesive layer and the supporting base material when measuring the adhesive force after heating described above. The sheet is mentioned. An adhesive sheet having an adhesive force after heating of 15 N / 25 mm or more and which does not cause anchoring failure when the adhesive force after heating is measured is a suitable example corresponding to an adhesive sheet in which an adhesive layer is adhered to a substrate. Is.

In the pressure-sensitive adhesive sheet disclosed herein, for example, a liquid pressure-sensitive adhesive composition is brought into contact with the first surface of a base material, and the pressure-sensitive adhesive composition is cured on the first surface to form a pressure-sensitive adhesive layer. And can be preferably produced by a method including in this order. Curing of the pressure-sensitive adhesive composition may involve one or more of drying, cross-linking, polymerization, cooling, etc. of the pressure-sensitive adhesive composition. According to the method of forming the pressure-sensitive adhesive layer by curing the liquid pressure-sensitive adhesive composition on the first surface of the base material, the cured pressure-sensitive adhesive layer is bonded to the first surface of the base material. Compared with the method of arranging the pressure-sensitive adhesive layer on the first surface, the anchoring property of the pressure-sensitive adhesive layer on the base material can be enhanced. Utilizing this, a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is adhered to a base material can be suitably manufactured.

In some embodiments, as a method of contacting the liquid pressure-sensitive adhesive composition with the first surface of the base material, a method of directly applying the pressure-sensitive adhesive composition to the first surface of the base material can be adopted. By bringing the first surface (adhesive surface) of the pressure-sensitive adhesive layer cured on the first surface of the base material into contact with the peeling surface, the second surface of the pressure-sensitive adhesive layer is fixed to the first surface of the base material. Moreover, it is possible to obtain a pressure-sensitive adhesive sheet having a structure in which the first surface of the pressure-sensitive adhesive layer is in contact with the peeled surface. As the peeling surface, the surface of the peeling liner, the back surface of the base material that has been peeled off, or the like can be used.

Further, for example, in the case of a photocurable pressure-sensitive adhesive composition using a partial polymer (polymer syrup) of a monomer raw material, for example, the pressure-sensitive adhesive composition is applied to a peeling surface and then the applied pressure-sensitive adhesive composition is applied. By covering the object with the first surface of the base material, the uncured adhesive composition is brought into contact with the first surface of the base material, and in that state, it is sandwiched between the first surface of the base material and the peeled surface. The pressure-sensitive adhesive layer may be formed by irradiating the pressure-sensitive adhesive composition with light to cure the pressure-sensitive adhesive composition.

The method exemplified above does not limit the method for producing the pressure-sensitive adhesive sheet disclosed herein. In the production of the pressure-sensitive adhesive sheet disclosed herein, an appropriate method capable of fixing the pressure-sensitive adhesive layer to the first surface of the base material can be used alone or in combination of two or more types. Examples of such methods include a method of curing a liquid pressure-sensitive adhesive composition on the first surface of a substrate to form a pressure-sensitive adhesive layer as described above, and a method of forming a pressure-sensitive adhesive layer on the first surface of a substrate. Examples thereof include a method of applying a surface treatment that enhances the anchoring property. For example, when the anchoring property of the pressure-sensitive adhesive layer on the base material can be sufficiently improved by providing an undercoat layer on the first surface of the base material, the cured pressure-sensitive adhesive layer is used as the first surface of the base material. An adhesive sheet may be manufactured by a method of adhering to. Further, the anchorability of the pressure-sensitive adhesive layer to the base material can be improved by selecting the material of the base material and the composition of the pressure-sensitive adhesive. Further, by applying a temperature higher than room temperature to the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer on the first surface of the base material, the anchoring property of the pressure-sensitive adhesive layer on the base material can be enhanced. The temperature applied to enhance the anchoring property may be, for example, about 35 ° C. to 80 ° C., 40 ° C. to 70 ° C. or higher, or 45 ° C. to 60 ° C.

The pressure-sensitive adhesive sheet disclosed herein is a pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive layer provided on the first surface of the base material and a second pressure-sensitive adhesive layer provided on the second surface of the base material (that is, both sides). In the form of an adhesive sheet with an adhesive base material), the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may have the same structure or different structures. When the composition of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is different, the difference may be, for example, a difference in composition or a difference in structure (thickness, surface roughness, formation range, formation pattern, etc.). For example, the second pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer that does not contain the polymer B. Further, the surface of the second adhesive layer (second adhesive surface) may have an adhesive force N ₅₀ of less than 5N / 25mm, may be less than 3N / 25mm, may be less than 1.5N / 25mm, and may be 1N /. It may be less than 25 mm.

<Adhesive sheet with release liner>
The pressure-sensitive adhesive sheet disclosed herein may take the form of a pressure-sensitive adhesive product in which the surface (adhesive surface) of the pressure-sensitive adhesive layer is brought into contact with the peel-off surface of the release liner. Accordingly, the present specification provides an adhesive sheet (adhesive product) with a release liner comprising any of the pressure-sensitive adhesive sheets disclosed herein and a release liner having a release surface that abuts on the adhesive surface of the pressure-sensitive adhesive sheet. obtain.

The thickness of the release liner is not particularly limited, but is usually about 5 μm to 200 μm. When the thickness of the release liner is within the above range, it is preferable because it is excellent in the workability of bonding to the pressure-sensitive adhesive layer and the workability of peeling off from the pressure-sensitive adhesive layer. In some embodiments, the thickness of the release liner may be, for example, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. Further, the thickness of the release liner may be, for example, 100 μm or less, or 80 μm or less, from the viewpoint of facilitating the release from the pressure-sensitive adhesive layer. If necessary, the release liner may be subjected to a known antistatic treatment such as a coating type, a kneading type, or a vapor deposition type.

The release liner is not particularly limited, and is, for example, a release liner having a release layer on the surface of a liner base material such as a resin film or paper (paper on which a resin such as polyethylene is laminated) or a fluoropolymer. A release liner made of a resin film formed of a low adhesive material such as (polytetrafluoroethylene, etc.) or a polyolefin resin (polyethylene, polypropylene, etc.) can be used. Since the surface smoothness is excellent, a release liner having a release layer on the surface of the resin film as a liner base material or a release liner made of a resin film formed of a low adhesive material can be preferably adopted. The resin film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and is, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, or a vinyl chloride copolymer. Examples thereof include films, polyester films (PET films, PBT films, etc.), polyurethane films, ethylene-vinyl acetate copolymer films, and the like. For forming the peeling layer, for example, a silicone-based stripping agent, a long-chain alkyl-based stripping agent, an olefin-based stripping agent, a fluorine-based stripping agent, a fatty acid amide-based stripping agent, molybdenum sulfide, silica powder, or the like can be used. , A known stripping agent can be used. The use of a silicone-based stripping agent is particularly preferred.

The thickness of the release layer is not particularly limited, but is usually about 0.01 μm to 1 μm, preferably about 0.1 μm to 1 μm. The method for forming the release layer is not particularly limited, and a known method according to the type of the release treatment agent to be used can be appropriately adopted.

<Use>
The pressure-sensitive adhesive sheet provided by this specification can exhibit good reworkability at the initial stage of being bonded to an adherend, for example, thereby suppressing a decrease in yield and improving the quality of products containing the pressure-sensitive adhesive sheet. Can contribute to. The adhesive strength of the pressure-sensitive adhesive sheet can be greatly increased by aging (mild heating around 50 ° C., aging, a combination thereof, etc.). For example, the pressure-sensitive adhesive sheet can be firmly adhered to the adherend by heating at a desired timing. Taking advantage of these characteristics, the adhesive sheet disclosed herein is preferable in various fields for the purpose of fixing, joining, molding, decorating, protecting, reinforcing, supporting, shock absorbing, etc. of the members contained in various products. Can be used.

The pressure-sensitive adhesive sheet disclosed herein is, for example, in the form of a pressure-sensitive adhesive sheet with a base material provided with an adhesive layer on at least the first side of a film-like base material having a first surface and a second surface, and is attached to an adherend. It can be preferably used as a reinforcing film that is attached to reinforce the adherend. In such a reinforcing film, as the film base material, a film containing a resin film as a base film can be preferably used. Further, from the viewpoint of enhancing the reinforcing performance, it is preferable that the pressure-sensitive adhesive layer is adhered to the first surface of the film-like substrate.
For example, in optical members used in optical products and electronic members used in electronic products, advanced integration, miniaturization, weight reduction, and thinning are progressing, and a plurality of thin optical members having different linear expansion coefficients and thicknesses / Electronic members can be laminated. By attaching the reinforcing film as described above to such a member, it is possible to impart appropriate rigidity to the optical member / electronic member. Thereby, in the manufacturing process and / or the product after manufacturing, it is possible to suppress curl and bending caused by the stress that may occur between the plurality of members having different linear expansion coefficients and thicknesses.
Further, in the manufacturing process of optical products / electronic products, in the aspect of performing shape processing such as cutting on a thin optical member / electronic member as described above, processing is performed by attaching a reinforcing film to the member. It is possible to alleviate the local stress concentration on the optical member / electronic member and reduce the risk of cracks, cracks, peeling of laminated members, and the like. Handling a reinforcing member by attaching it to an optical member / electronic member also reduces local stress concentration during transportation, stacking, rotation, etc. of the member, and suppresses bending or bending due to the weight of the member. Can be useful.
Furthermore, devices such as optical products and electronic products containing the above-mentioned reinforcing film collide with flying objects when the device is dropped or placed under a heavy object at the stage of being used by consumers in the market. Even when unintentional stress is applied, such as in the case, the stress applied to the device can be relieved by including the reinforcing film in the device. Therefore, the durability of the device can be improved by including the reinforcing film in the device.

In addition, the pressure-sensitive adhesive sheet disclosed herein can be preferably used, for example, in a manner of being attached to a member constituting various portable devices (portable devices). Here, "portable" means that it is not enough to be portable, but that an individual (standard adult) has a level of portability that is relatively easy to carry. do. Examples of portable devices here include mobile phones, smartphones, tablet PCs, notebook PCs, various wearable devices, digital cameras, digital video cameras, sound devices (portable music players, IC recorders, etc.), and calculators (portable music players, IC recorders, etc.). Calculators, etc.), mobile game devices, electronic dictionaries, electronic notebooks, electronic books, in-vehicle information devices, mobile radios, mobile TVs, mobile printers, mobile scanners, mobile modems and other portable electronic devices, as well as mechanical watches and pocketbooks. Clocks, flashlights, hand mirrors, etc. may be included. Examples of the members constituting the portable electronic device may include an optical film or a display panel used for an image display device such as a thin layer display such as a liquid crystal display or a film type display. The adhesive sheet disclosed herein can also be preferably used in a mode of being attached to various members in automobiles, home appliances and the like.

Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in such specific examples. In addition, "part" and "%" in the following description are based on weight unless otherwise specified.

(Preparation of polymer A1)
60 parts of 2-ethylhexyl acrylate (2EHA), 15 parts of N-vinyl-2-pyrrolidone (NVP), 10 parts of methyl methacrylate (MMA) in a reaction vessel equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube and a cooler. , 2-Hydroxyethyl acrylate (HEA) 15 parts, and ethyl acetate 200 parts as a polymerization solvent were charged, stirred at 60 ° C. under a nitrogen atmosphere for 2 hours, and then 2,2'-azobisisobuty as a thermal polymerization initiator. 0.2 part of butyronitrile (AIBN) was added and the reaction was carried out at 60 ° C. for 6 hours to obtain a solution of the polymer A1. The Mw of this polymer A1 was 1.1 million.

(Preparation of polymer B1)
In a reaction vessel equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube and a cooler, 40 parts of MMA, 20 parts of n-butyl methacrylate (BMA), 20 parts of 2-ethylhexyl methacrylate (2EHMA), and a functional group equivalent of 900 g / mol. Polyorganosiloxane skeleton-containing methacrylate monomer (trade name: X-22-174ASX, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) 8.7 parts, polyorganosiloxane skeleton-containing methacrylate monomer having a functional group equivalent of 4600 g / mol (trade name: KF) −2012, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) 11.3 parts, 100 parts of ethyl acetate, and 0.5 part of thioglycerol as a chain transfer agent were added, and the mixture was stirred at 70 ° C. under a nitrogen atmosphere for 1 hour and then heated. 0.2 part of AIBN was added as a polymerization initiator and reacted at 70 ° C. for 2 hours, then 0.1 part by weight of AIBN was added as a thermal polymerization initiator and subsequently reacted at 80 ° C. for 5 hours. In this way, a solution of polymer B1 was obtained. Mw of the polymer B1 was 2.2 × 10 ^4.

(Preparation of polymer B2)
A solution of polymer B2 ^{having a Mw of 16.5 × 10 4} was obtained in the same manner as in the preparation of polymer B1 except that thioglycerol was not used.

The weight average molecular weight of each of the above-mentioned polymers was measured under the following conditions using a GPC device (manufactured by Tosoh Corporation, HLC-8220GPC) and determined by polystyrene conversion.
[GPC conditions]
-Sample concentration: 0.2 wt% (tetrahydrofuran (THF) solution)
-Sample injection volume: 10 μL
・ Eluent: THF ・ Flow rate: 0.6 mL / min
・ Measurement temperature: 40 ° C
·column:
Sample column; TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2)
Reference column; TSKgel SuperH-RC (1)
-Detector: Differential refractometer (RI)

<Making an adhesive sheet>
(Example 1)
In a solution of the polymer A1, 2 parts of the polymer B1 and an isocyanate-based cross-linking agent (trade name: Takenate D110N, trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Kagaku Co., Ltd.) were added to 100 parts of the polymer A1 contained in the solution. Five parts were added and mixed uniformly to prepare a pressure-sensitive adhesive composition C1.
The pressure-sensitive adhesive composition C1 is directly applied to the front surface of a polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc., trade name "Lumilar") having a thickness of 75 μm as a supporting base material, and heated at 110 ° C. for 2 minutes to dry. By doing so, a pressure-sensitive adhesive layer having a thickness of 15 μm was formed. The peeling surface of the peeling liner was attached to the surface (adhesive surface) of this pressure-sensitive adhesive layer. As the release liner, MRQ25T100 (a release liner having a release layer with a silicone-based release treatment agent on one side of a polyester film, thickness 25 μm) manufactured by Mitsubishi Chemical Corporation was used. In this way, the adhesive sheet according to Example 1 was obtained in the form of an adhesive sheet with a release liner in which the release surface of the release liner was in contact with the adhesive surface.

(Examples 2 to 4)
The pressure-sensitive adhesive compositions C2 to C4 were prepared in the same manner as in the preparation of the pressure-sensitive adhesive composition C1 except that the type of the polymer B or the amount of the cross-linking agent used was changed as shown in Table 1. In the same manner as in the production of the pressure-sensitive adhesive sheet according to Example 1 except that these pressure-sensitive adhesive compositions C2 to C4 are used, the pressure-sensitive adhesive sheet according to Examples 2 to 4 is applied to the pressure-sensitive adhesive surface with the peel-off surface of the release liner. Obtained in the form of an adhesive sheet with a peeling liner in contact.

<Storage modulus G'(150 ° C)>
The storage elastic modulus G'(150 ° C.) of the pressure-sensitive adhesive layer was determined by dynamic viscoelasticity measurement. Specifically, except that the pressure-sensitive adhesive layer is formed on the peel-off surface of the release liner instead of the PET film, the pressure-sensitive adhesive layer is formed under basically the same conditions as in each example, and the thickness is increased by stacking a plurality of the pressure-sensitive adhesive layers. A pressure-sensitive adhesive layer of about 2 mm was formed. The obtained adhesive layer was punched into a disk shape with a diameter of 7.9 mm, and the sample was sandwiched between parallel plates to fix it. The dynamic viscoelasticity was measured under the following conditions, and the storage elastic modulus G'(150 ° C.) was determined. The pressure-sensitive adhesive layer to be measured may be formed by applying the corresponding pressure-sensitive adhesive composition to the peel-off surface of the release liner or the like in a layered manner and drying or curing the pressure-sensitive adhesive layer.
-Measurement mode: Shear mode-Temperature range: -50 ° C to 200 ° C
・ Temperature rise rate: 5 ° C / min
・ Measurement frequency: 1Hz

<Measurement of adhesive strength (23 ° C)>
The adhesive sheet according to each example was cut to a width of 25 mm together with the release liner as a test piece, and a SUS plate (SUS304BA plate) cleaned with toluene was used as an adherend, and the adhesive strength N ₂₃ and the adhesive strength N were carried out by the following procedure. ₅₀ and adhesive strength N ₈₀ were measured.
(Measurement of adhesive strength N ₂₃₎
Under a standard environment of 23 ° C. and 50% RH, the peeling liner covering the adhesive surface of each test piece was peeled off, and the exposed adhesive surface was pressure-bonded to the adherend by reciprocating a 2 kg roller once. After the test piece crimped to the adherend in this way is left in the above standard environment for 30 minutes, a universal tensile compression tester (device name "tensile compression tester, TCM-1kNB" manufactured by Minebea) is used. , JIS Z0237, 180 ° peeling adhesive strength (resistance to the above tension) was measured under the conditions of a peeling angle of 180 degrees and a tensile speed of 300 mm / min. The measurement was performed three times, and the average value thereof is shown in Table 1 as the _{adhesive strength N 23 [N / 25 mm].}
(Measurement of adhesive strength N ₅₀₎
The test piece crimped to the adherend in the same manner as in the measurement of the adhesive strength ₂₃ was held in an environment of 50 ° C. for 15 minutes, then left in the standard environment for 30 minutes, and then peeled off by 180 ° in the same manner. Was measured. The measurement was performed three times, and the average value thereof is shown in Table 1 as an _{adhesive force N 50 [N / 25 mm].}
(Measurement of the pressure-sensitive adhesive force _{N 80)}
The test piece crimped to the adherend was heated at 80 ° C. for 5 minutes in the same manner as in the measurement of the adhesive strength ₂₃ , then left in the standard environment for 30 minutes, and then peeled off by 180 ° and the adhesive strength was measured in the same manner. bottom. The measurement was performed three times, and the average value thereof is shown in Table 1 as the _{adhesive strength N 80 [N / 25 mm].} It was confirmed that none of the adhesive sheets according to Examples 1 to 4 caused anchoring failure when the _{adhesive strength N 80 was measured.}

Based on these adhesive strength measurement results, the adhesive strength increase ratios N ₈₀ / N ₅₀ and N ₅₀ / N ₂₃ were calculated. The results are shown in Table 1.

As shown in Table 1, the pressure-sensitive adhesive sheet according to Examples 1 to 4 is a pressure-sensitive adhesive containing polymer A and polymer B, which is a copolymer of a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer. are those provided with a layer, all exhibited 5N / 25 mm or more adhesion _{N 50.} It can be seen that these adhesive sheets can exhibit good reworkability at the initial stage of attachment, and then the adhesive strength can be increased to a predetermined value or more by mild heating at about 50 ° C. Further, in Examples 1 to 3 using the pressure-sensitive adhesive layer having a storage elastic modulus G'(150 ° C.) at 150 ° C. of 10,000 Pa or more and 90,000 Pa or less, particularly good results were obtained. Specifically, it was possible to further improve the _{adhesive force N 50} while suppressing the adhesive force N ₂₃ corresponding to the initial stage of pasting to a low level.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The techniques described in the claims include various modifications and modifications of the specific examples exemplified above.

1,2,3 Adhesive sheet 10 Supporting base material 10A 1st surface 10B 2nd surface 21 Adhesive layer (1st adhesive layer)
21A Adhesive surface (first adhesive surface)
21B adhesive surface (second adhesive surface)
22 Adhesive layer (second adhesive layer)
22A Adhesive surface (second adhesive surface)
31,32 Peeling liner 100, 200, 300 Adhesive sheet with peeling liner (adhesive product)

Claims (14)

An adhesive sheet containing an adhesive layer,
The pressure-sensitive adhesive layer contains polymer A and polymer B, which is a copolymer of a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer.
_{An adhesive sheet having an adhesive force N 50} measured at 23 ° C. of 5 N / 25 mm or more after being bonded to a stainless steel plate and held at 50 ° C. for 15 minutes. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive _{adhesive force N 23} measured after being bonded to a stainless steel plate and held at 23 ° C. for 30 minutes is 3 N / 25 mm or less. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive force N _{50 is 5 times or more the pressure-sensitive adhesive force N 23} measured after being bonded to a stainless steel plate and held at 23 ° C. for 30 minutes. The invention according to any one of claims 1 to 3, wherein the adhesive force N ₈₀ measured at 23 ° C. after being bonded to a stainless steel plate and held at 80 ° C. for 5 minutes _{is not more than twice the adhesive force N 50.} Adhesive sheet. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the storage elastic modulus G'(150 ° C.) of the pressure-sensitive adhesive layer at 150 ° C. is 10,000 Pa or more and 90,000 Pa or less. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the polymer A contained in the pressure-sensitive adhesive layer is chemically crosslinked. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the polymer B has a weight average molecular weight of 100,000 or more. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the polymer B has a weight average molecular weight of less than 80,000. The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, wherein the content of the polymer B in the pressure-sensitive adhesive layer is 0.5 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the polymer A. The pressure-sensitive adhesive sheet according to any one of claims 1 to 9, wherein the polymer A is an acrylic polymer. The pressure-sensitive adhesive sheet according to claim 10, wherein the acrylic polymer contains a monomer having a nitrogen atom-containing ring as a monomer unit thereof. Any of claims 1 to 11, wherein the monomer component for preparing the polymer B contains, as the (meth) acrylic monomer, a monomer having a glass transition temperature of homopolymer of 50 ° C. or higher in a proportion of 60% by weight or less. The adhesive sheet described in item 1. The pressure-sensitive adhesive according to any one of claims 1 to 12, wherein the support base material has a first surface and a second surface, and the pressure-sensitive adhesive layer is laminated on at least the first surface of the support base material. Sheet. An adhesive sheet containing an adhesive layer,
The pressure-sensitive adhesive layer contains polymer A and polymer B, which is a copolymer of a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer.
A pressure-sensitive adhesive sheet having a storage elastic modulus G'(150 ° C.) at 150 ° C. of the pressure-sensitive adhesive layer of 10,000 Pa or more and 90,000 Pa or less.

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