CN113286702B

CN113286702B - Pressure-sensitive adhesive sheet

Info

Publication number: CN113286702B
Application number: CN201980088358.5A
Authority: CN
Inventors: 铃木立也; 仲野武史; 家田博基
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2019-01-08
Filing date: 2019-12-26
Publication date: 2024-03-22
Anticipated expiration: 2039-12-26
Also published as: CN113286702A; JPWO2020145188A1; TWI843788B; TW202035606A; KR20210112348A; WO2020145188A1; JP7555271B2

Abstract

The invention provides a novel adhesive sheet which can exhibit good reworkability at the initial stage of adhering to an adherend and can greatly increase the adhesive force in a short time by mild heating at about 50 ℃. Provided is an adhesive sheet comprising an adhesive layer. The adhesive layer contains a polymer A and a polymer B, wherein the polymer B is a copolymer of a (methyl) acrylic monomer and a monomer with a polyorganosiloxane skeleton. The adhesive sheet exhibits an adhesive force N of 5N/25mm or more ₅₀ . Here, adhesive force N ₅₀ Refers to the adhesion force measured at 23 ℃ after adhering to a stainless steel plate and holding at 50 ℃ for 15 minutes.

Description

Pressure-sensitive adhesive sheet

Technical Field

The present invention relates to an adhesive sheet.

The present application claims priority based on japanese patent application No. 2019-001349, filed on 1/8 of 2019, the entire contents of which are incorporated herein by reference.

Background

The pressure-sensitive adhesive sheet is used for the purpose of bonding the adherends to each other, fixing the article to the adherend, reinforcing the adherend, and the like by firmly adhering the pressure-sensitive adhesive sheet to the adherend. Conventionally, for such a purpose, an adhesive sheet exhibiting high adhesive force from the initial stage of attachment has been used. Recently, as in patent documents 1 to 3, there have been proposed pressure-sensitive adhesive sheets which exhibit low pressure-sensitive adhesive force at the initial stage of adhering to an adherend and can greatly improve the pressure-sensitive adhesive force after that. By using the pressure-sensitive adhesive sheet having such characteristics, it is possible to exhibit re-adhesiveness (reworkability) before the pressure-sensitive adhesive strength increases, which is useful for suppressing a reduction in yield due to a misattachment and a damage in the adhesion of the pressure-sensitive adhesive sheet, and to exhibit strong pressure-sensitive adhesive properties after the pressure-sensitive adhesive strength increases, which are suitable for the intended use of the pressure-sensitive adhesive sheet.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2014-224227

Patent document 2: japanese patent No. 5890596

Patent document 3: japanese patent No. 5951153

Disclosure of Invention

Problems to be solved by the invention

The pressure-sensitive adhesive sheet described in the above prior art document is configured as follows: the adhesive agent exhibits low adhesive force at the initial stage of application, and the adhesive force rises to a predetermined value or more by exposure to a high temperature of about 80 ℃ or by leaving the adhesive agent for a period of about 2 days. This can control the increase of the adhesive force with good reliability. However, such an adhesive sheet is used in a production process of a product, and the adhesive force is advantageously increased by a simpler process from the viewpoint of improving efficiency (production efficiency) in the production process in such an application. For example, if an adhesive sheet capable of increasing the adhesive force in a short time by heating (mild heating) closer to normal temperature is provided, the adhesive force increasing treatment can be effectively and reliably performed without a deviation, and therefore, it is advantageous in terms of improvement of production efficiency. The pressure-sensitive adhesive sheet having such characteristics can be applied to an adherend which is not expected to be exposed to a high temperature state, and therefore development of new uses can also be expected. Accordingly, an object of the present invention is to provide a novel pressure-sensitive adhesive sheet which exhibits good reworkability at the initial stage of adhering to an adherend and can greatly increase the adhesive force in a short time by mild heating at about 50 ℃.

Solution for solving the problem

According to the present specification, there is provided an adhesive sheet including an adhesive layer. The adhesive layer contains a polymer A and a polymer B, wherein the polymer B is a copolymer of a (methyl) acrylic monomer and a monomer with a polyorganosiloxane skeleton. The adhesive sheet exhibits an adhesive force N of 5N/25mm or more ₅₀ . Here, adhesive force N ₅₀ Refers to the adhesion force measured at 23 ℃ after adhering to a stainless steel plate and holding at 50 ℃ for 15 minutes.

The adhesive sheet having the above-described structure can exhibit good reworkability in the initial stage of attachment due to the action of the polymer B having a polyorganosiloxane skeleton. Thereafter, the adhesive force can be increased to a predetermined value or more by gentle heating at about 50 ℃.

Adhesive force N measured after the adhesive sheets of several preferred modes were adhered to stainless steel plates and kept at 23℃for 30 minutes ₂₃ Is 3N/25mm or less. An adhesive sheet satisfying this characteristic is suppressed in adhesive force at the initial stage of attachment, and therefore exhibits good reworkability. That is, both of the initial light peelability (reworkability) and the adhesive force increase after mild heating can be favorably achieved.

The adhesive force N of the adhesive sheet of several preferred embodiments ₅₀ For the adhesive force N measured after adhering to a stainless steel plate and holding at 23℃for 30 minutes ₂₃ More than 5 times of the total number of the components. By means of the adhesive force N as described above ₅₀ Relative to the adhesive force N ₂₃ Is 5 times or more (N) ₅₀ /N ₂₃ More than or equal to 5), the adhesive sheet can exhibit good reworkability at the initial stage of attachment, and the adhesive force can be greatly increased by subsequent heating or the like.

Adhesive force N measured at 23℃after the adhesive sheets of several modes were adhered to stainless steel plates and kept at 80℃for 5 minutes ₈₀ Can be the adhesive force N ₅₀ Is 2 times or less (i.e., N ₈₀ /N ₅₀ 2) or less. Since the adhesive sheet satisfying such characteristics is sufficiently increased in adhesive strength by mild heating at about 50 ℃, it is not required to be exposed to a further high temperature (specifically, heating at about 80 ℃) in order to obtain a strong adhesive strength. By using an adhesive sheet satisfying such characteristics, the adhesive force can be more effectively increased to a desired level than beforeGrade.

The storage modulus G' (150 ℃) of the pressure-sensitive adhesive layer at 150℃is preferably 10,000Pa or more and 90,000Pa or less. An adhesive layer satisfying the above 150 ℃ storage modulus is easy to exert good adhesive properties, and the polymer B is easy to move in the adhesive layer, so that an adhesive force increase after mild heating can be well achieved based on its mobility.

In the technology disclosed herein, the polymer a contained in the adhesive layer is typically chemically crosslinked. Thus, the adhesive sheet can exhibit excellent adhesive properties. In addition, in the above-described configuration in which the degree of crosslinking is limited so that the storage modulus G' (150 ℃) becomes equal to or less than a predetermined value, an increase in adhesive force after mild heating can be satisfactorily achieved based on the mobility of the polymer B in the adhesive layer. In some embodiments, the adhesive layer may contain a crosslinking agent in an amount of more than 0 parts by weight and 10 parts by weight or less relative to 100 parts by weight of the polymer a. By using the crosslinking agent, chemical crosslinking satisfying desired properties can be satisfactorily achieved, and the storage modulus G' (150 ℃) in a predetermined range can be satisfactorily achieved.

In several embodiments, the weight average molecular weight of the polymer B may be 100,000 or more. Even in the case of using the polymer B having a Mw equal to or greater than a predetermined value, the effect produced by the technique disclosed herein can be satisfactorily achieved.

In several preferred ways, the weight average molecular weight of the aforementioned polymer B may be less than 80,000. By using the polymer B having an Mw of less than the predetermined value, the adhesive force after mild heating can be favorably increased.

In some embodiments, the content of the polymer B in the pressure-sensitive adhesive layer may be, for example, in a range of 0.5 parts by weight to 50 parts by weight with respect to 100 parts by weight of the polymer a. By using the content in the above range, the adhesive force after mild heating can be favorably increased.

The polymer a is preferably an acrylic polymer. According to the adhesive layer comprising the polymer a as the acrylic polymer and the polymer B as the copolymer of the (meth) acrylic monomer and the monomer having the polyorganosiloxane skeleton, an increase in adhesive force after mild heating can be satisfactorily achieved.

In several modes, the aforementioned acrylic polymer preferably contains a monomer having a nitrogen atom-containing ring as its monomer unit. By using the polymer a containing a monomer unit having a nitrogen atom-containing ring in combination with the polymer B, an increase in adhesive force after mild heating can be satisfactorily achieved.

In some preferred embodiments, the monomer component for preparing the polymer B contains a monomer having a homopolymer glass transition temperature of 50 ℃ or higher as the (meth) acrylic monomer (monomer M2) at a ratio of 60 wt% or less. By limiting the copolymerization ratio of the monomer M2 having a Tg of 50 ℃ or higher to a predetermined value or less in the polymer B, an increase in adhesive force after mild heating can be satisfactorily achieved based on the mobility of the polymer B in the vicinity of 50 ℃. As the monomer M2, an alkyl (meth) acrylate (i.e., an alkyl (meth) acrylate) having a homopolymer Tg of 50℃or higher is preferably used.

The adhesive sheet disclosed herein may be implemented in the following form: the pressure-sensitive adhesive sheet comprises a support substrate having a first surface and a second surface, and the pressure-sensitive adhesive layer is laminated on at least the first surface of the support substrate, that is, the pressure-sensitive adhesive sheet with a substrate. Such a pressure-sensitive adhesive sheet with a base material is excellent in handling and workability. As the support base material, for example, a resin film having a thickness of 30 μm or more can be preferably used.

Further, according to the present specification, there is provided an adhesive sheet including an adhesive layer. The adhesive layer contains a polymer A and a polymer B, wherein the polymer B is a copolymer of a (methyl) acrylic monomer and a monomer with a polyorganosiloxane skeleton. The adhesive layer has a storage modulus G' (150 ℃) of 10,000Pa or more and 90,000Pa or less at 150 ℃. With the adhesive sheet having the adhesive layer satisfying the above 150 ℃ storage modulus, it is possible to exhibit good reworkability based on the action of the polymer B, and thereafter to increase the adhesive force by mild heating at around 50 ℃.

Drawings

Fig. 1 is a cross-sectional view schematically showing the constitution of an adhesive sheet according to an embodiment.

Fig. 2 is a cross-sectional view schematically showing the constitution of an adhesive sheet according to another embodiment.

Fig. 3 is a cross-sectional view schematically showing the constitution of an adhesive sheet according to another embodiment.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described. The matters necessary for the practice of the present invention other than those specifically mentioned in the present specification can be understood by those skilled in the art based on the teachings and technical knowledge at the time of application concerning the practice of the present invention described in the present specification. The present invention may be implemented based on the contents disclosed in the present specification and technical knowledge in the art.

In the drawings, members and portions that serve the same function may be denoted by the same reference numerals, and repeated description may be omitted or simplified. In order to clearly illustrate the present invention, the embodiments described in the drawings are schematically illustrated, and do not necessarily accurately represent the dimensions and scale of the actually provided product.

In the present specification, the "acrylic polymer" means a polymer having a polymer structure containing a monomer unit derived from a (meth) acrylic monomer, and typically means a polymer containing a monomer unit derived from a (meth) acrylic monomer in an amount of more than 50% by weight. The (meth) acrylic monomer means a monomer having at least one (meth) acryloyl group in 1 molecule. Here, "(meth) acryl" means including acryl and methacryl. Therefore, the concept of the (meth) acrylic monomer expressed herein may include both a monomer having an acryl group (acrylic monomer) and a monomer having a methacryl group (methacrylic monomer). Similarly, in the present specification, "(meth) acrylic acid" means inclusive of acrylic acid and methacrylic acid, and "(meth) acrylic acid ester" means inclusive of acrylic acid ester and methacrylic acid ester.

< structural example of adhesive sheet >

The pressure-sensitive adhesive sheet disclosed herein comprises a pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet disclosed herein may be in the form of a base-material-provided pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is laminated on one surface or both surfaces of a support base material, or may be in the form of a base-material-free pressure-sensitive adhesive sheet having no support base material. Hereinafter, the support substrate may be simply referred to as "substrate".

Fig. 1 schematically shows the structure of an adhesive sheet according to an embodiment. The pressure-sensitive adhesive sheet 1 is configured as a single-sided pressure-sensitive adhesive sheet with a base material, and includes: a sheet-like 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. The adhesive layer 21 is fixed to the first surface 10A side of the support substrate 10. The pressure-sensitive adhesive sheet 1 is used by attaching the pressure-sensitive adhesive layer 21 to an adherend. As shown in fig. 1, the pressure-sensitive adhesive sheet 1 before use (i.e., before attachment to an adherend) may be a component of a release liner-attached pressure-sensitive adhesive sheet 100 in which a surface (pressure-sensitive adhesive surface) 21A of the pressure-sensitive adhesive layer 21 is in contact with a release liner 31 having a releasable surface (release surface) at least on the side facing the pressure-sensitive adhesive layer 21. As the release liner 31, for example, a release liner having a release layer formed by providing a release agent on one surface of a sheet-like substrate (liner substrate) so that the one surface becomes a release surface can be preferably used. Alternatively, the release liner 31 may be omitted, and the pressure-sensitive adhesive sheet 1 may be wound around the support substrate 10 having the second surface 10B as the release surface, so that the pressure-sensitive adhesive surface 21A is brought into contact with the second surface 10B of the support substrate 10 (a roll form). When the adhesive sheet 1 is attached to an adherend, the release liner 31 or the second surface 10B of the support substrate 10 is peeled off from the adhesive surface 21A, and the exposed adhesive surface 21A is pressure-bonded to the adherend.

Fig. 2 schematically shows the structure of an adhesive sheet according to another embodiment. The pressure-sensitive adhesive sheet 2 is configured as a base-material-provided double-sided pressure-sensitive adhesive sheet comprising: a sheet-like support substrate 10 having a first surface 10A and a second surface 10B, an adhesive layer 21 provided on the first surface 10A side, and an adhesive layer 22 provided on the second surface 10B side. The adhesive layer (first adhesive layer) 21 is fixed to the first surface 10A of the support substrate 10, and the adhesive layer (second adhesive layer) 22 is fixed to the second surface 10B of the support substrate 10. The pressure-sensitive adhesive sheets 2 are used by attaching the pressure-sensitive adhesive layers 21 and 22 to different portions of an adherend. The portions to which the adhesive layers 21, 22 are attached may be portions of different members or portions within a single member. As shown in fig. 2, the pressure-sensitive adhesive sheet 2 before use may be a component of the release liner-attached pressure-sensitive adhesive sheet 200 in which 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 in contact with release liners 31 and 32, which are release surfaces, at least on the sides facing the pressure-sensitive adhesive layers 21 and 22, respectively. As the release liners 31 and 32, for example, a release liner having a release layer formed by providing a release layer with a release treatment agent on one surface of a sheet-like substrate (liner substrate) so that the one surface becomes a release surface can be preferably used. Alternatively, the release liner-attached adhesive sheet may be configured as follows: the release liner 32 is omitted, and a release liner 31 having both surfaces as release surfaces is used, and the release liner is overlapped with the adhesive sheet 2 and wound in a spiral shape, whereby the second adhesive surface 22A is in contact with the back surface of the release liner 31 (in a roll form).

Fig. 3 schematically shows the structure of an adhesive sheet according to yet another embodiment. The pressure-sensitive adhesive sheet 3 is formed as a base-material-free double-sided pressure-sensitive adhesive sheet formed of a pressure-sensitive adhesive layer 21. The adhesive sheet 3 is used by attaching a first adhesive surface 21A formed of one surface (first surface) of the adhesive layer 21 and a second adhesive surface 21B formed of the other surface (second surface) of the adhesive layer 21 to different portions of an adherend. As shown in fig. 3, the pressure-sensitive adhesive sheet 3 before use may be a component of a release liner-attached pressure-sensitive adhesive sheet 300 in which the first pressure-sensitive adhesive surface 21A and the second pressure-sensitive adhesive surface 21B are in contact with release liners 31 and 32, which are release surfaces, respectively, at least on the side facing the pressure-sensitive adhesive layer 21. Or may constitute a release liner-bearing adhesive sheet as follows: the release liner 32 is omitted, and a release liner 31 having both surfaces as release surfaces is used, and the release liner is overlapped with the adhesive sheet 3 and wound in a spiral shape, whereby the second adhesive surface 21B is in contact with the back surface of the release liner 31 (in a roll form).

The term "pressure-sensitive adhesive sheet" as used herein may include members called pressure-sensitive adhesive tapes, pressure-sensitive adhesive films, pressure-sensitive adhesive labels, and the like. The pressure-sensitive adhesive sheet may be in the form of a roll, may be in the form of a sheet, or may be cut, punched or the like into a suitable shape depending on the application and the manner of use. The pressure-sensitive adhesive layer in the technology disclosed herein is typically formed continuously, but is not limited thereto, and may be formed in a regular or irregular pattern such as a dot shape, a stripe shape, or the like, for example.

< adhesive layer >)

The adhesive sheet disclosed herein comprises an adhesive layer containing a polymer A and a polymer B, wherein the polymer B is a copolymer of a (meth) acrylic monomer and a monomer having a polyorganosiloxane skeleton. Such an adhesive layer may be formed of an adhesive composition containing a polymer B and a polymer a as a complete polymer or a partial polymer of the monomer raw material a. The form of the adhesive composition is not particularly limited, and may be various forms such as solvent-based, water-dispersed, hot-melt, active energy ray-curable (e.g., photo-curable), and the like.

(Polymer A)

As the polymer a, one or two or more of various polymers exhibiting rubber elasticity in a room temperature region, such as an acrylic polymer, a rubber polymer, a polyester polymer, a urethane polymer, a polyether polymer, a silicone polymer, a polyamide polymer, and a fluorine polymer, which are known in the art of adhesives, can be used. In the pressure-sensitive adhesive sheet disclosed herein, the polymer a is typically a main component of the polymer component contained in the pressure-sensitive adhesive layer, that is, a component accounting for more than 50% by weight, and may be, for example, a component accounting for 75% by weight or more of the above-mentioned polymer components. In some embodiments, the polymer a may be a component that is more than 50% by weight of the entire pressure-sensitive adhesive layer, or may be a component that is 70% by weight or more.

Glass transition temperature T of Polymer A _A The adhesive sheet disclosed herein may be selected so as to have preferable characteristics, without particular limitation. In several ways, T may be preferred _A Polymer a at less than 0 ℃. Adhesives comprising such polymers a exhibit moderate flowability (e.g. the mobility of the polymer chains contained in the adhesive) and are therefore suitable for practical useThe adhesive force of the adhesive sheet is increased to a predetermined value or more by gentle heating. T can be preferably used for the pressure-sensitive adhesive sheet disclosed herein _A The polymer A is used at a temperature of less than-10 ℃, less than-20 ℃, less than-30 ℃ or less than-35 ℃. In several ways, T _A The temperature may be less than-40℃or less than-50 ℃. T (T) _A The lower limit of (2) is not particularly limited. T is generally preferably used from the viewpoints of easiness in acquisition of materials and improvement in cohesive force of the adhesive layer _A A polymer A at a temperature of-80 ℃ or higher, -70 ℃ or-65 ℃. In several ways, T _A For example, the temperature may be-63℃or higher, may be-55℃or higher, may be-50℃or higher, or may be-45℃or higher.

In the present specification, the glass transition temperature (Tg) of a polymer refers to a nominal value described in a literature, a catalogue, or the like, or a Tg obtained from Fox formula based on the composition of monomer raw materials used in the preparation of the polymer. The Fox equation is a relational expression between Tg of the copolymer and glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below.

1/Tg＝Σ(Wi/Tgi)

In the above Fox formula, tg represents the glass transition temperature (unit: K) of the copolymer, wi represents the weight fraction (copolymerization ratio based on weight) of the monomer i in the copolymer, tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer i. In the case where the target polymer whose Tg is to be determined is a homopolymer, the Tg of the homopolymer coincides with the Tg of the target polymer.

The glass transition temperature of the homopolymer used for calculating Tg was the value described in the known data. Specifically, the values in "Polymer Handbook" (3 rd edition, john Wiley & Sons, inc., 1989) are listed. For the monomers described in the above Polymer Handbook, the highest value was used for the various values.

As the glass transition temperature of the homopolymer of the monomer not described in the Polymer Handbook, the values obtained by the following measurement methods were used.

Specifically, 100 parts by weight of monomer, 0.2 part by weight of 2,2' -azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent were charged into a reactor equipped with a thermometer, a stirrer, a nitrogen inlet pipe and a reflux condenser, and stirred for 1 hour while flowing nitrogen. After the oxygen in the polymerization system was removed in this manner, the temperature was raised to 63℃and the reaction was allowed to proceed for 10 hours. Then, the mixture was cooled to room temperature to obtain a homopolymer solution having a solid content of 33% by weight. Subsequently, the homopolymer solution was cast on a release liner, and dried to prepare a test sample (sheet-like homopolymer) having a thickness of about 2 mm. The test specimen was punched into a disk shape having a diameter of 7.9mm, clamped by parallel plates, and the viscoelasticity was measured by a shear mode at a temperature range of-70 to 150℃at a temperature rise rate of 5 ℃/min while applying a shear strain at a frequency of 1Hz using a viscoelasticity tester (model name "ARES" manufactured by TA Instruments Japan Co.), and the temperature corresponding to the peak top temperature of tan. Delta. Was defined as Tg of the homopolymer.

The weight average molecular weight (Mw) of polymer A is generally suitably about 20X 10 ⁴ The above is not particularly limited. With the polymer a of this Mw, an adhesive exhibiting good cohesion is easily obtained. From the standpoint of obtaining higher cohesion, in several ways, the Mw of polymer A may be, for example, 30X 10 ⁴ The above may be 40×10 ⁴ The above may be 50×10 ⁴ The above may be 60×10 ⁴ The above may be 80×10 ⁴ The above. In addition, the Mw of polymer A is generally suitably about 500X 10 ⁴ The following is given. The polymer a of the Mw is suitable for realizing an adhesive sheet having an adhesive force at the initial stage of application and a high adhesive force after low temperature and heating, because it is easy to form an adhesive agent exhibiting moderate fluidity (mobility of polymer chains). From the viewpoint of improving the compatibility with polymer B, it is also preferable that the Mw of polymer a is not too high. In several ways, the Mw of polymer A may be, for example, 250X 10 ⁴ Hereinafter, it may be 200X 10 ⁴ Hereinafter, 150×10 may be used ⁴ The following is given.

In the present specification, mw of the polymer a and the polymer B described later can be determined by Gel Permeation Chromatography (GPC) and converted into polystyrene. More specifically, the Mw can be measured according to the methods and conditions described in examples described below.

As the polymer a in the adhesive sheet disclosed herein, an acrylic polymer can be preferably used. When an acrylic polymer is used as the polymer a, good compatibility with the polymer B tends to be easily obtained. When the compatibility of the polymer a and the polymer B is good, the improvement of the mobility of the polymer B in the adhesive layer is preferable because the reduction of the initial adhesion and the improvement of the adhesion after heating can be facilitated.

The acrylic polymer may be, for example, a polymer containing 50% by weight or more of monomer units derived from an alkyl (meth) acrylate, that is, a polymer in which 50% by weight or more of the total amount of monomer components (monomer raw materials a) used for producing the acrylic polymer is an alkyl (meth) acrylate. As the alkyl (meth) acrylate, one having 1 to 20 carbon atoms (i.e., C _1-20 Alkyl (meth) acrylates of linear or branched alkyl groups. From the viewpoint of easily obtaining a balance of characteristics, the (meth) acrylic acid C in the monomer raw material A _1-20 The ratio of the alkyl ester may be, for example, 50% by weight or more, 60% by weight or more, or 70% by weight or more. For the same reason, the (meth) acrylic acid C in the monomer raw material A _1-20 The ratio of the alkyl ester may be, for example, 99.9% by weight or less, 98% by weight or less, or 95% by weight or less. In several modes, (meth) acrylic acid C in monomer feed A _1-20 The ratio of the alkyl ester may be, for example, 90% by weight or less, 85% by weight or less, or 80% by weight or less.

As (meth) acrylic acid C _1-20 Non-limiting examples of alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,Isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like.

Of these, at least (meth) acrylic acid C is preferably used _1-18 Alkyl esters, more preferably at least C (meth) acrylic acid _1-14 Alkyl esters. In several modes, the acrylic polymer may contain a polymer selected from the group consisting of (meth) acrylic acid C _4-12 Alkyl esters (preferably acrylic acid C _4-10 Alkyl esters, e.g. acrylic acid C _6-10 Alkyl esters) as monomer units. For example, an acrylic polymer containing one or both of n-Butyl Acrylate (BA) and 2-ethylhexyl acrylate (2 EHA) is preferable, and an acrylic polymer containing at least 2EHA is particularly preferable. As other (meth) acrylic acid C which can be preferably used _1-18 Examples of the alkyl esters include methyl acrylate, methyl Methacrylate (MMA), n-Butyl Methacrylate (BMA), 2-ethylhexyl methacrylate (2 EHMA), and isostearyl acrylate (ISTA).

The monomer raw material a may contain, as necessary, other monomers (copolymerizable monomers) copolymerizable with the alkyl (meth) acrylate as a main component together with the alkyl (meth) acrylate. As the copolymerizable monomer, a monomer having a polar group (for example, a carboxyl group, a hydroxyl group, a nitrogen atom-containing ring, or the like) can be suitably used. The monomer having a polar group may help introduce a crosslinking point into the acrylic polymer or improve the cohesive force of the acrylic polymer. The copolymerizable monomers may be used singly or in combination of two or more.

As non-limiting specific examples of the copolymerizable monomer, the following monomers can be mentioned.

Hydroxyl-containing monomers: for example, hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate.

Monomers having a nitrogen atom-containing ring: such as N-vinyl-2-pyrrolidone, N-methyl vinyl pyrrolidone, N-vinyl pyridine, N-vinyl piperidone, N-vinyl pyrimidine, N-vinyl piperazine, N-vinyl pyrazine, N-vinyl pyrrole, N-vinyl imidazole, N-vinyl oxazole, N- (meth) acryl-2-pyrrolidone, N- (meth) acryl piperidine, N- (meth) acryl pyrrolidine, N-vinyl morpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1, 3-oxazin-2-one, N-vinyl-3, 5-morpholinedione, N-vinyl pyrazole, N-vinyl isoxazole, N-vinyl thiazole, N-vinyl isothiazole, N-vinyl pyridazine, and the like;

Monomers having a succinimide skeleton such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, and N- (meth) acryloyl-8-oxyhexamethylene succinimide;

maleimides such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; and

Examples of the amine-based compound include N-methyl-itaconimide, N-ethyl-itaconimide, N-butyl-itaconimide, N-octyl-itaconimide, N-2-ethylhexyl-itaconimide, N-cyclohexyl-itaconimide, and N-month Gui Jiyi-itaconimide.

Carboxyl group-containing monomers: such as 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: such as maleic anhydride, itaconic anhydride.

Epoxy group-containing monomers: for example, epoxy group-containing acrylates such as glycidyl (meth) acrylate and 2-ethyl glycidyl (meth) acrylate, allyl glycidyl ether, glycidyl (meth) acrylate, and the like.

Cyano-containing monomers: such as acrylonitrile, methacrylonitrile, and the like.

Isocyanate group-containing monomer: such as 2-isocyanatoethyl (meth) acrylate, and the like.

Amide group-containing monomers: such as (meth) acrylamide; n, N-dialkyl (meth) acrylamides such as N, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-dipropyl (meth) acrylamide, N-diisopropyl (meth) acrylamide, N-di (N-butyl) (meth) acrylamide, N-di (t-butyl) (meth) acrylamide, and the like; n-alkyl (meth) acrylamides such as N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-N-butyl (meth) acrylamide; n-vinylcarboxylic acid amides such as N-vinylacetamide; monomers having a hydroxyl group and an amide group, for example, N-hydroxyalkyl (meth) acrylamides 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) (meth) acrylamide, and the like; monomers having an alkoxy group and an amide group, for example, N-alkoxyalkyl (meth) acrylamides such as N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide; and N, N-dimethylaminopropyl (meth) acrylamide, N- (meth) acryloylmorpholine, and the like.

Aminoalkyl (meth) acrylates: such as aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, N-diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate.

Alkoxy-containing monomers: for example, alkoxyalkyl (meth) acrylates such as 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxypropyl (meth) acrylate, and the like; alkoxy alkylene glycol (meth) acrylates such as methoxy ethylene glycol (meth) acrylate and methoxy polypropylene glycol (meth) acrylate.

Monomers containing sulfonic or phosphoric groups: such as styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonate, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, acryloxynaphthalene sulfonic acid, 2-hydroxyethyl acryl phosphate, and the like.

(meth) acrylic acid ester having alicyclic hydrocarbon group: for example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and the like.

(meth) acrylic acid esters having an aromatic hydrocarbon group: for example, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, and the like.

Vinyl ethers: such as vinyl alkyl ethers, e.g., methyl vinyl ether and ethyl vinyl ether.

Vinyl esters: such as vinyl acetate, vinyl propionate, and the like.

Aromatic vinyl compound: such as styrene, alpha-methylstyrene, vinyltoluene, and the like.

Olefins: such as ethylene, butadiene, isoprene, isobutylene, etc.

And heterocyclic (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate, halogen atom-containing (meth) acrylates such as vinyl chloride or fluorine atom-containing (meth) acrylates, silicon atom-containing (meth) acrylates such as silicone (meth) acrylates, and (meth) acrylates obtained from terpene compound derivative alcohols.

When such a copolymerizable monomer is used, the amount thereof is not particularly limited, and is usually preferably 0.01% by weight or more of the monomer raw material A. The amount of the copolymerizable monomer may be 0.1% by weight or more, or 1% by weight or more of the monomer raw material a, from the viewpoint of more preferably exhibiting the effect caused by the use of the copolymerizable monomer. The amount of the copolymerizable monomer may be 50% by weight or less, preferably 45% by weight or less of the monomer raw material a. This prevents the cohesive force of the adhesive from becoming too high, and improves the sticky feel at normal temperature (25 ℃). In some embodiments, the amount of the copolymerizable monomer may be 40% by weight or less, or 35% by weight or less of the monomer raw material a.

In several ways, monomer feed 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 improved well. When the monomer having a nitrogen atom-containing ring is contained 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. Thus, an adhesive sheet having a greatly improved adhesive force by mild heating can be easily obtained.

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

Here, R in the above general formula (M1) ¹ Is a 2-valent organic group.

Specific examples of the N-vinyl cyclic amide include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1, 3-oxazin-2-one, and N-vinyl-3, 5-morpholindione. N-vinyl-2-pyrrolidone, N-vinyl-2-caprolactam are particularly preferred.

The amount of the monomer having a nitrogen atom-containing ring 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 monomer having a nitrogen atom-containing ring 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. The amount of the monomer having a nitrogen atom-containing ring is usually preferably 40% by weight or less, may be 30% by weight or less, may be 20% by weight or less, or may be 18% by weight or less of the monomer raw material a from the viewpoints of improving the tackiness at normal temperature (25 ℃) and improving the flexibility at low temperature.

In several preferred embodiments, monomer feed a contains hydroxyl-containing monomers. 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 improved well. In addition, the hydroxyl group-containing monomer provides a reaction point with a crosslinking agent (for example, an isocyanate-based crosslinking agent) described below, and the cohesive force of the adhesive can be improved by the crosslinking reaction.

As the hydroxyl group-containing monomer, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, N- (2-hydroxyethyl) (meth) acrylamide, and the like can be suitably used. Preferable examples thereof include 2-hydroxyethyl acrylate (HEA), 4-hydroxybutyl acrylate (4 HBA), and N- (2-hydroxyethyl) acrylamide (HEAA).

The amount of the hydroxyl group-containing monomer is not particularly limited, and is usually not less than 0.01% by weight (preferably not less than 0.1% by weight, for example not less than 0.5% by weight) of the monomer raw material a. In some embodiments, the amount of the hydroxyl group-containing monomer may be 1% by weight or more of the monomer material a, 5% by weight or more, or 10% by weight or more. The amount of the hydroxyl group-containing monomer is usually 40% by weight or less of the monomer raw material a, preferably 30% by weight or less, 20% by weight or less, or 10% by weight or 5% by weight or less, from the viewpoints of the mobility of the polymer B in the adhesive layer, the improved tackiness at normal temperature (25 ℃) and the improved flexibility at low temperature.

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

In the mode of combining the monomer having a ring having a nitrogen atom with the hydroxyl group-containing monomer in the monomer raw material A, the content (W _N ) With the content of hydroxyl-containing monomers (W) _OH ) The relation (weight basis) of (a) is not particularly limited. W (W) _N /W _OH For example, it may be 0.01 or more, usually 0.05 or more, preferably 0.1 or more, 0.2 or more, 0.5 or more, or 0.7 or more. In addition, W _N /W _OH For example, it may be 100 or less, usually 20 or less, may be 10 or less, may be 5 or less, may be 2 or less, or may be 1.5 or less.

In some embodiments, the monomer material a preferably contains no monomer (monomer S1) having a polyorganosiloxane skeleton, which is preferably used as a constituent of the monomer material B described later, or the content of the monomer is less than 10 wt% (more preferably less than 5 wt%, for example less than 2 wt%) of the monomer material a. By using the monomer material a having such a composition, an adhesive sheet having excellent both of the initial reworkability and the strong adhesion after the increase of the adhesive force can be realized. For the same reason, in the other modes, the monomer raw material a preferably does not contain the monomer S1, or in the case of containing the monomer S1, the content thereof (weight basis) is lower than the content of the monomer S1 in the monomer raw material B.

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 suitably employed. Among the several ways, a solution polymerization method may be preferably employed. The polymerization temperature in the solution polymerization may be appropriately selected depending on the types of monomers and solvents used, the types of polymerization initiators, and the like, and may be, for example, about 20 to 170 ℃ (typically about 40 to 140 ℃).

The initiator for polymerization may be appropriately selected from conventionally known thermal polymerization initiators, photopolymerization initiators, and the like according to the polymerization method. The polymerization initiator may be used singly or in combination of two or more.

Examples of the thermal polymerization initiator include azo-based polymerization initiators (for example, 2,2' -azobisisobutyronitrile, 2' -azobis-2-methylbutyronitrile, dimethyl 2,2' -azobis (2-methylpropionate), 4' -azobis-4-cyanovaleric acid, azobisisovaleronitrile 2,2' -azobis (2-amidinopropane) dihydrochloride, 2' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ] dihydrochloride, 2' -azobis (2-methylpropionamidine) disulfate, 2' -azobis (N, N ' -dimethylene isobutyl amidine) dihydrochloride, etc.); persulfates such as potassium persulfate; peroxide-based polymerization initiators (e.g., dibenzoyl peroxide, t-butyl peroxymaleate, lauroyl peroxide, etc.); redox-type polymerization initiators, and the like. The amount of the thermal polymerization initiator is not particularly limited, and may be, for example, in the range of 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the monomer component (monomer raw material a) used in the production of the acrylic polymer.

The photopolymerization initiator is not particularly limited, and 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, a photoactive oxime-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzil-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, a thioxanthone-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, and the like can be used. The amount of the photopolymerization initiator used is not particularly limited, and may be, for example, in the range of 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the monomer raw material a.

In some embodiments, the polymer a may be included in an adhesive composition for forming an adhesive layer in the form of a partial polymer (polymer slurry) obtained by polymerizing a part of the monomer component by irradiating Ultraviolet (UV) to a mixture obtained by compounding the polymerization initiator in the monomer raw material a described above. The polymerization can be completed by applying the adhesive composition containing the polymer slurry to a predetermined object to be coated and irradiating ultraviolet rays. That is, the polymer slurry can be grasped as a precursor of the polymer a. The adhesive layer disclosed herein can be formed, for example, using an adhesive composition containing the above-described polymer slurry and polymer B.

(Polymer B)

The polymer B in the technology disclosed herein is a copolymer of a monomer having a polyorganosiloxane skeleton (hereinafter also referred to as "monomer S1") and a (meth) acrylic monomer. Due to the low polarity and mobility of the polyorganosiloxane structure derived from the monomer S1, the polymer B can function as an adhesion-force-increase retarder that suppresses adhesion force to an adherend in the initial stage of adhesion and increases adhesion force to the adherend by heating. The monomer S1 is not particularly limited, and any monomer containing a polyorganosiloxane skeleton may be used. The monomer S1, due to its low polarity derived from its structure, promotes the concentrated distribution of the polymer B on the surface of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet before use (before application to an adherend), and exhibits light peelability (low adhesion) at the initial stage of application. As the monomer S1, a monomer having a structure with a polymerizable reactive group at one end can be preferably used. By copolymerizing such a monomer S1 with a (meth) acrylic monomer, a polymer B having a polyorganosiloxane skeleton in a side chain is formed. The polymer B having such a structure is easily a substance having low initial adhesion and high adhesion after mild heating, due to the mobility and mobility of the side chains. In some embodiments, as the monomer S1, a monomer having a polymerizable reactive group at one end and having no functional group at the other end that causes a crosslinking reaction with the polymer a may be preferably used. The polymer B obtained by copolymerizing the monomer S1 having such a structure is likely to be a polymer having low initial adhesion and high adhesion after heating due to the mobility of the polyorganosiloxane structure derived from the monomer S1.

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 reactive silicone oil include X-22-174ASX, X-22-2426, X-22-2475, and KF-2012, which are single-end reactive silicone oils manufactured by Xinyue chemical industries, inc. The monomers S1 may be used singly or in combination of two or more.

Here, R in the above general formulae (1) and (2) ³ Is hydrogen or methyl, R ⁴ Is methyl or 1-valent organic group, m and n are integers of 0 or more.

The functional group equivalent of the monomer S1 may take an appropriate value within a range where the desired effect is exhibited by using the monomer S1, and is not limited to a specific range. The functional group equivalent is, for example, 100g/mol or more, 200g/mol or more, 300g/mol or more (for example, 500g/mol or more), preferably 700g/mol or more, more preferably 800g/mol or more, still more preferably 850g/mol or more, and particularly preferably 1500g/mol or more, from the viewpoint of sufficiently suppressing the initial adhesion. In several embodiments, from the viewpoint of both low adhesion at the initial stage of attachment and an increase in adhesive force after mild heating, the functional group equivalent may be 3000g/mol or more, 4500g/mol or more, 6000g/mol or more, 9000g/mol or more, 12000g/mol or more, or 15000g/mol or more (for example, 16000g/mol or more). The functional group equivalent of the monomer S1 may be, for example, 50000g/mol or less. From the viewpoint of sufficiently improving the adhesive force, the functional group equivalent is, for example, preferably 30000g/mol or less, and more preferably 20000g/mol or less. In several ways, the functional group equivalent of monomer S1 may be less than 18000g/mol, may be less than 15000g/mol, may be less than 10000g/mol, may be less than 6000g/mol, and may be less than 5000g/mol. When the functional group equivalent of the monomer S1 is within the above range, the compatibility (for example, the compatibility with the base polymer) and the mobility in the adhesive layer can be easily adjusted to a proper range, and it is easy to realize an adhesive layer which combines both the low initial adhesion and the increase in adhesive force after mild heating.

Non-limiting examples of preferred ranges of functional group equivalents for monomer S1 include: 700g/mol to 50000g/mol, 700g/mol to 30000g/mol, 700g/mol to 20000g/mol, 700g/mol to 18000g/mol, 700g/mol to 15000g/mol, 800g/mol to 10000g/mol, 850g/mol to 6000g/mol, 1500g/mol to 5000g/mol. In several ways, the preferred range of functional group equivalent of monomer S1 may be 3000g/mol or more and 50000g/mol or less, 6000g/mol or more and 50000g/mol or less, 12000g/mol or more and 50000g/mol or less, 15000g/mol or more and 50000g/mol or less.

Herein, "functional group equivalent" refers to the weight of the backbone (e.g., polydimethylsiloxane) bonded to an average of 1 functional group. The labeling unit g/mol is 1mol in terms of functional group. The functional equivalent of the monomer S1 can be determined, for example, by Nuclear Magnetic Resonance (NMR) based ¹ The spectrum intensity of H-NMR (proton NMR) was calculated. Based on ¹ The functional group equivalent (g/mol) of the monomer S1 of the spectrum intensity of H-NMR can be calculated from ¹ A general structure analysis method for H-NMR spectrum analysis is described in Japanese patent No. 5951153, if necessary.

In the case where two or more monomers having different functional group equivalents are used as the monomer S1, an arithmetic average value may be used as the functional group equivalent of the monomer S1. Namely, the monomer comprises n monomers (monomer S1 ₁ Monomer S1 ₂ … … monomer S1 _n ) The functional group equivalent of the monomer S1 of (2) can be calculated by the following formula.

Functional group equivalent of monomer S1(g/mol) = (monomer S1) ₁ Functional equivalent of (2) x monomer S1 ₁ Compounding amount of (C) and monomer S1 ₂ Functional equivalent of (2) x monomer S1 ₂ Compounded amount of + … … +monomer S1 _n Functional equivalent of (2) x monomer S1 _n Compounding amount of (a)/(monomer S1) ₁ Compounding amount of (C) and monomer S1 ₂ Compounded amount of + … … +monomer S1 _n Is a compound amount of (a)

The content of the monomer S1 may be an appropriate value within a range where the desired effect is exhibited by using the monomer S1, and is not limited to a specific range. In some embodiments, the total amount of the monomer components (monomer raw materials B) used for preparing the polymer B may be, for example, 5% by weight or more, and from the viewpoint of more preferably exhibiting 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. 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 may be 50% by weight or less, 40% by weight or less, or 30% by weight or less, from the viewpoints of polymerization reactivity and compatibility. If the content of the monomer S1 is less than 5 wt%, initial adhesion may not be sufficiently suppressed. If the content of the monomer S1 is more than 60 wt%, there is a possibility that the increase of the adhesive force becomes insufficient.

The monomer raw material B contains a (meth) acrylic monomer copolymerizable with the monomer S1 in addition to the monomer S1. The mobility of the polymer B in the adhesive layer can be appropriately adjusted by copolymerizing one or two or more (meth) acrylic monomers with the monomer S1. Copolymerizing monomer S1 with a (meth) acrylic monomer may also help improve the compatibility of polymer B with polymer a (e.g., an acrylic polymer).

Examples of the (meth) acrylic monomer that can be used as the monomer raw material B include alkyl (meth) acrylates. For example, as the constituent component of the monomer raw material B, one or more of the monomers exemplified above as the alkyl (meth) acrylate that can be used when the polymer a is an acrylic polymer can be used. In several ways, the monomer feed B may contain (meth) acrylic acid C _4-12 Alkyl esters (preferably (meth) acrylic acid C _4-10 Alkyl esters, e.g. C (meth) acrylic acid _6-10 Alkyl esters). In other modes, monomer feed B may contain methacrylic acid C _1-18 Alkyl esters (preferably methacrylic acid C _1-14 Alkyl esters, e.g. methacrylic acid C _1-10 Alkyl esters). The monomer raw material B may contain, for example, one or two or more selected from MMA, BMA and 2EHMA as a (meth) acrylic monomer.

As other examples of the (meth) acrylic monomer, there may be mentioned (meth) acrylic esters having alicyclic hydrocarbon groups. 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 material B may contain at least one selected from the group consisting of dicyclopentanyl methacrylate, isobornyl methacrylate, and cyclohexyl methacrylate as the (meth) acrylic monomer.

The content of the alkyl (meth) acrylate and the alicyclic hydrocarbon group-containing (meth) acrylate in the monomer raw material B may be, for example, 10% by weight or more and 95% by weight or less, 20% by weight or more and 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, or 50% by weight or more and 85% by weight or less. The use of the alkyl (meth) acrylate is advantageous from the viewpoint of easiness of increase in adhesive force based on mild heating. In some embodiments, the content of the (meth) acrylate having an alicyclic hydrocarbon group may be less than 50 wt% of the monomer raw material B, may be less than 30 wt%, may be less than 15 wt%, may be less than 10 wt%, or may be less than 5 wt%. (meth) acrylic esters having alicyclic hydrocarbon groups may not be used.

In some preferred embodiments, the (meth) acrylic monomer as a constituent of the monomer raw material B may contain a monomer M2 having a homopolymer Tg of 50 ℃ or higher. In the polymer B, by copolymerizing the monomer S1 and the monomer M2, the mobility and mobility of the polyorganosiloxane structural part accompanying the temperature increase can be easily controlled well, and it is easy to achieve both of the initial light releasability (reworkability) and the adhesive force increase after mild heating. In several embodiments, the homopolymer of monomer M2 may have a Tg of 60℃or higher, 70℃or higher, 80℃or higher, or 90℃or higher. The upper limit of Tg of the homopolymer of the monomer M2 is not particularly limited, and is usually 200 ℃ or lower, from the viewpoint of ease of synthesis of the polymer B, and the like. In some embodiments, the homopolymer of the monomer M2 may have a Tg of 180℃or less, 150℃or less, or 120℃or less, for example.

As the monomer M2, for example, a monomer satisfying the condition of Tg of the homopolymer may be used from among the (meth) acrylic monomers exemplified above. For example, one or two or more monomers selected from the group consisting of alkyl (meth) acrylates and (meth) acrylates having alicyclic hydrocarbon groups can be used. As the alkyl (meth) acrylate, an alkyl methacrylate in which the carbon number of the alkyl group is in the range of 1 to 4 can be preferably used.

In the case where the monomer material B contains the monomer M2, the content of the monomer M2 may be, for example, 5 wt% or more, 10 wt% or more, 15 wt% or more, 20 wt% or more, 25 wt% or more, or 30 wt% or more of the monomer material B. In some embodiments, the content of the monomer M2 may be 35 wt% or more, 40 wt% or more, 45 wt% or more, 50 wt% or more, or 55 wt% or more of the monomer raw material B. The content of the monomer M2 may be, for example, 90% by weight or less, and is usually 80% by weight or less, preferably 75% by weight or less, 70% by weight or less, or 65% by weight or less. In several preferred embodiments, the content of monomer M2 is 60% by weight or less (for example 50% by weight or less, typically 42% by weight or less). In the polymer B, by limiting the copolymerization ratio of the monomer M2 having a Tg of 50 ℃ or higher to a predetermined value or less, the adhesive force after mild heating can be favorably increased based on the mobility of the polymer B in the vicinity of 50 ℃. 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 may be preferably applied to a case where the monomer M2 contains one or more monomers selected from the group consisting of alkyl (meth) acrylates and (meth) acrylates having alicyclic hydrocarbon groups, or a case where the monomer M2 contains one or more monomers selected from the group consisting of alkyl (meth) acrylates (e.g., alkyl methacrylates). As a preferable example of this embodiment, an embodiment in which the monomer M2 contains MMA is mentioned.

In several embodiments, the (meth) acrylic monomer may also include a monomer M3 having a homopolymer Tg of less than 50 ℃ (typically, -20 ℃ or more and less than 50 ℃). By using the monomer M3, an adhesive sheet which gives an even balance between adhesive force and cohesive force after the adhesive force has increased can be easily obtained. From the viewpoint of easily exhibiting this effect, the monomer M3 is preferably used in combination with the monomer M2.

As the monomer M3, for example, a monomer satisfying the condition of Tg of the homopolymer may be used from among the (meth) acrylic monomers exemplified above. For example, one or two or more monomers selected from the group consisting of alkyl (meth) acrylates may be used.

In the embodiment in which the monomer material B contains the monomer M3, the content of the monomer M3 may be, for example, 5 wt% or more, 10 wt% or more, 15 wt% or more, 20 wt% or more, 25 wt% or more, 30 wt% or more, or 35 wt% or more of the monomer material B. The content of the monomer M3 is usually 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 may be preferably applied, for example, to a manner in which the monomer M3 contains one or two or more monomers selected from alkyl (meth) acrylates (e.g., alkyl methacrylates).

In several modes of the adhesive sheet disclosed herein, the monomer raw material B is preferably a homopolymer having a content of monomers having Tg higher than 170 ℃ of 30 wt% or less. Here, unless otherwise specified, the term "the content of the monomer" in the present specification is not more than X% by weight means that the content of the monomer is 0% by weight, that is, means that the monomer is not substantially contained. The substantial absence of the monomer means that at least the above monomer is not used intentionally. If the copolymerization ratio of the monomer having Tg higher than 170 ℃ is high, the mobility of the polymer B tends to be insufficient, and the increase of the adhesive force by heating to a temperature range higher than 50 ℃ is difficult in some cases.

In several modes, the monomer raw material B preferably contains at least MMA as the (meth) acrylic monomer. N is easily obtained from the MMA-copolymerized polymer B ₅₀ Large adhesive sheets. The ratio of MMA contained in the monomer material B to the total amount of the (meth) acrylic monomers may be, for example, 5% by weight or more, 10% by weight or more, 20% by weight or more, 30% by weight or more, or 40% by weight or more. In several modes, the ratio of MMA in the total amount of the above (meth) acrylic monomers may be, for example, more than 50% by weight, more than 55% by weight, more than 60% by weight, more than 65% by weight, 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, and may be 90% by weight or less or 85% by weight or less. In some preferred embodiments, the ratio of MMA to the total amount of the (meth) acrylic monomers may be 75 wt% or less, 65 wt% or less, 60 wt% or less, or 55 wt% or less (for example, 50 wt% or less) from the viewpoint of an increase in adhesive force after mild heating.

Examples of the monomer that can be included together with the monomer S1 as the monomer unit constituting the polymer B include carboxyl group-containing monomers, anhydride group-containing monomers, hydroxyl group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, isocyanate group-containing monomers, amide group-containing monomers, monomers having a nitrogen atom ring (N-vinyl cyclic amide, monomers having a succinimide skeleton, maleimides, itaconimides, and the like), (meth) acrylic aminoalkyl esters, vinyl ethers, olefins, (meth) acrylic esters having an aromatic hydrocarbon group, heterocyclic ring-containing (meth) acrylic esters, halogen atom-containing (meth) acrylic esters, and (meth) acrylic esters derived from terpene compound derivative alcohols, which are exemplified above as the monomers that can be used when the polymer a is an acrylic polymer.

As another example of the monomer that can be contained together with the monomer S1 as the monomer unit constituting the polymer B, there can be mentioned: oxyalkylene di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, and the like; a monomer having a polyoxyalkylene skeleton, for example, a polymerizable polyoxyalkylene ether having a polymerizable functional group such as a (meth) acryloyl group, a vinyl group, or an allyl group at one end of a polyoxyalkylene chain such as polyethylene glycol or polypropylene glycol, and having an ether structure (such as an alkyl ether, an aryl ether, or an arylalkyl ether) at the other end; alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxypropyl (meth) acrylate, and the like; alkali metal (meth) acrylate salts; a polyvalent (meth) acrylate such as trimethylolpropane tri (meth) acrylate: halogenated vinyl compounds such as vinylidene chloride and 2-chloroethyl (meth) acrylate; oxazolinyl group-containing monomers such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, and 2-isopropenyl-2-oxazoline; aziridinyl monomers such as (meth) acryloylaziridine and 2-aziridinylethyl (meth) acrylate; hydroxy-containing vinyl monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, adducts of lactones and 2-hydroxyethyl (meth) acrylate; fluorine-substituted vinyl-containing monomers such as alkyl (meth) acrylates; reactive halogen-containing vinyl monomers such as 2-chloroethyl vinyl ether and vinyl monochloroacetate; silicone-containing vinyl monomers such as vinyl trimethoxysilane, γ - (meth) acryloxypropyl trimethoxysilane, allyl trimethoxysilane, trimethoxysilylpropyl allylamine, and 2-methoxyethoxy trimethoxysilane; and macromers having a radically polymerizable vinyl group at the end of the monomer obtained by polymerizing the vinyl group; etc. They may be copolymerized with the monomer S1 singly or in combination of two or more.

Among several modes, as the polymer B, a polymer having no functional group which causes a crosslinking reaction with the polymer a can be preferably used. In other words, the polymer B is preferably contained in the adhesive layer in a form not chemically bonded to the polymer a. The adhesive layer containing the polymer B in such a form is excellent in the mobility of the polymer B when heated, and is suitable for improving the adhesive force increasing ratio. The functional group that reacts with the polymer a by crosslinking varies depending on the kind of functional group that the polymer a has, and may be, for example, an epoxy group, an isocyanate group, a carboxyl 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 1000 or more, or 5000 or more, for example. From the viewpoint of satisfactorily exhibiting an increase in adhesion after mild heating, 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. In several embodiments, the Mw of polymer B may be 50,000 or greater, may be 80,000 or greater, may be 100,000 or greater, or may be 120,000 or greater (e.g., 150,000 or greater). The upper limit of Mw of the polymer B may be, for example, 500,000 or less, 350,000 or less, or less than 100,000. From the viewpoint of adjusting the compatibility and mobility in the adhesive layer to a proper range and satisfactorily exhibiting an increase in adhesive force after mild heating, the Mw of the polymer B may be less than 80,000, may be less than 70,000, may be less than 50,000, may be less than 40,000, may be less than 20,000, and may further be less than 10,000.

In several preferred modes, the Mw of polymer B is preferably lower than the Mw of polymer A. Thus, it is easy to realize an adhesive sheet which combines good reworkability in the initial stage of attachment and an increase in adhesive force after mild heating. The Mw of the polymer B may be, for example, 0.8 times or less, 0.75 times or less, 0.5 times or less, 0.3 times or less, 0.1 times or less, 0.05 times or less, or 0.03 times or less (for example, 0.02 times or less) of the Mw of the polymer a.

The polymer B can be produced by polymerizing the above 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.

In order to adjust the molecular weight of the polymer B, a chain transfer agent may be used as needed. Examples of the chain transfer agent used include: mercapto compounds such as octyl mercaptan, lauryl mercaptan, t-nonyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, and α -thioglycerol; thioglycolate esters such as thioglycolate, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, ethylene glycol thioglycolate, neopentyl glycol thioglycolate, pentaerythritol thioglycolate, and the like; alpha-methylstyrene dimer; etc.

The amount of the chain transfer agent is not particularly limited, but is usually 0.05 to 20 parts by weight, preferably 0.1 to 15 parts by weight, more preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the monomer. By adjusting the addition amount of the chain transfer agent in this manner, a polymer B having an appropriate molecular weight can be obtained. The chain transfer agent may be used singly or in combination of two or more.

As means for adjusting the molecular weight of the polymer B, various conventionally known means including the use of the chain transfer agent may be used alone or in appropriate combination. The same applies to the molecular weight of polymer A. Non-limiting examples of such means include selection of a polymerization method, selection of the kind/amount of a polymerization initiator, selection of a polymerization temperature, selection of the kind/amount of a polymerization solvent in a solution polymerization method, selection of the light irradiation intensity in a photopolymerization method, and the like. The person skilled in the art will understand how to obtain a polymer having a desired molecular weight based on the technical knowledge at the time of the present application, including the description of the present application including the specific examples described later.

In the pressure-sensitive adhesive sheet disclosed herein, the amount of the polymer B may be, for example, 0.1 part by weight or more, or 0.5 part by weight or more, or 1 part by weight or more, or 2 parts by weight or more, based on 100 parts by weight of the amount of the polymer a, from the viewpoint of obtaining a higher effect. In some embodiments, the amount of the polymer B may be 3 parts by weight or more, 4 parts by weight or more, or 5 parts by weight or more, for example, from the viewpoint of improving reworkability. The amount of the polymer B may be 75 parts by weight or less, 60 parts by weight or less, or 50 parts by weight or less, based on 100 parts by weight of the amount of the polymer a. From the viewpoint of avoiding excessive decrease in cohesive force of the adhesive layer, the amount of the polymer B may be, for example, 40 parts by weight or less, or 35 parts by weight or less, 30 parts by weight or less, or 25 parts by weight or less per 100 parts by weight of the polymer a. From the viewpoint of obtaining a higher adhesive force after heating, the amount of the polymer B may be 20 parts by weight or less, 17 parts by weight or less, 15 parts by weight or less, 12 parts by weight or less, 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) in several embodiments.

The pressure-sensitive adhesive layer may contain a polymer (any polymer) other than the polymer a and the polymer B as needed within a range that does not significantly impair the performance of the pressure-sensitive adhesive sheet disclosed herein. The amount of such an optional polymer is usually 20% by weight or less, preferably 15% by weight or less, and preferably 10% by weight or less of the entire polymer component contained in the pressure-sensitive adhesive layer. In some embodiments, the amount of the optional polymer may be 5 wt% or less, 3 wt% or less, or 1 wt% or less of the entire polymer component. The pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer substantially free of polymers other than the polymer a and the polymer B.

(crosslinking agent)

For the purpose of adjusting the cohesive force, a crosslinking agent may be used in the adhesive layer as needed. Examples of the crosslinking agent include epoxy crosslinking agents, isocyanate crosslinking agents, silicone crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyl etherified melamine crosslinking agents, and metal chelate crosslinking agents, which are known in the art of adhesives. In particular, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, and a metal chelate-based crosslinking agent are suitably used. The crosslinking agent may be used singly or in combination of two or more.

Specifically, examples of the isocyanate-based crosslinking agent include: toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, and adducts thereof with polyhydric alcohols such as trimethylolpropane. Alternatively, a compound having at least 1 isocyanate group and 1 or more unsaturated bond in 1 molecule, specifically, 2-isocyanatoethyl (meth) acrylate or the like may be used as the isocyanate-based crosslinking agent. They may be used singly or in combination of two or more.

Examples of the epoxy crosslinking agent include bisphenol a, epichlorohydrin type epoxy resins, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerol triglycidyl ether, 1, 6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidylamine, N' -tetraglycidyl m-xylylenediamine, and 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane. These may be used singly or in combination of two or more.

Examples of the metal chelate compound include aluminum, iron, tin, titanium, and nickel, and examples of the chelating agent component include acetylene, methyl acetoacetate, and ethyl lactate. They may be used singly or in combination of two or more.

The amount of the crosslinking agent used is not particularly limited, and may be, for example, more than 0 parts by weight based on 100 parts by weight of the polymer a. The amount of the crosslinking agent to be used may be, for example, 0.01 parts by weight or more, and preferably 0.05 parts by weight or more based on 100 parts by weight of the polymer a. By increasing the amount of the crosslinking agent, the adhesive force at the initial stage of adhesion is suppressed, and the reworkability tends to be improved. In several embodiments, the crosslinking agent may be used in an amount of 0.1 parts by weight or more, 0.5 parts by weight or more, or 0.8 parts by weight or more, based on 100 parts by weight of the polymer a. On the other hand, from the viewpoint of appropriately allowing the mobility of the polymer B and obtaining a gentle increase in adhesive force after heating, the amount of the crosslinking agent is usually 15 parts by weight or less, and may be 10 parts by weight or less, or may be 5 parts by weight or less, relative to 100 parts by weight of the polymer a.

The technology disclosed herein can be preferably carried out in such a manner that at least an isocyanate-based crosslinking agent is used as the crosslinking agent. From the viewpoint of both good reworkability at the initial stage of attachment and an increase in adhesive force after mild heating, the amount of the isocyanate-based crosslinking agent may be, for example, 0.01 parts by weight or more, 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), 5 parts by weight or less, 3 parts by weight or less, 1.5 parts by weight or less, 1.2 parts by weight or less, or 0.8 parts by weight or less (for example, 0.6 parts by weight or less) based on 100 parts by weight of the polymer a in several embodiments.

When an isocyanate-based crosslinking agent is used in the constitution in which the adhesive layer contains a hydroxyl group-containing monomer as a monomer unit, the amount W of the hydroxyl group-containing monomer is not particularly limited _OH The amount W relative to the isocyanate-based crosslinking agent _NCO Can be set as W based on weight _OH /W _NCO The amount is 2 or more. By increasing the amount of the hydroxyl group-containing monomer used for the isocyanate-based crosslinking agent in this manner, a crosslinked structure suitable for greatly increasing the adhesive force after mild heating relative to the adhesive force at the initial stage of application can be formed. In several ways, W _OH /W _NCO The ratio may be 3 or more, may be 5 or more, may be 10 or more, may be 20 or more, may be 30 or more, or may be 50 or more. W (W) _OH /W _NCO The upper limit of (2) is not particularly limited, and W is preferably selected from the viewpoint of the degree of crosslinking which allows the polymer B to moderately move by mild heating _OH /W _NCO For example, the content may be 500 or less, 200 or less, 100 or less, or 50 or less.

In order to more effectively perform any of the above-described crosslinking reactions, a crosslinking catalyst may be used. As the crosslinking catalyst, for example, a tin catalyst (particularly dioctyltin dilaurate) can be preferably used. The amount of the crosslinking catalyst is not particularly limited, and may be set to about 0.0001 parts by weight to 1 part by weight relative to 100 parts by weight of the polymer a, for example.

The adhesive layer may be formed of a polyfunctional monomer as needed. The polyfunctional monomer can contribute to the purpose of adjusting the cohesive force and the like by being used in place of the crosslinking agent described above or in combination with the crosslinking agent. For example, a polyfunctional monomer may be preferably used in the adhesive layer formed from the photocurable 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, neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ethylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1, 12-dodecanediol di (meth) acrylate, trimethylol propane tri (meth) acrylate, tetramethylol methane tri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl glycol (meth) acrylate, and hexyl glycol di (meth) acrylate. Among them, trimethylolpropane tri (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, dipentaerythritol hexa (meth) acrylate can be suitably used. The polyfunctional monomer may be used singly or in combination of two or more.

The amount of the polyfunctional monomer varies depending on the molecular weight, the number of functional groups, and the like, and is usually in the range of about 0.01 to 3.0 parts by weight relative to 100 parts by weight of the polymer a. In some embodiments, the amount of the polyfunctional monomer 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. By increasing the amount of the polyfunctional monomer, the adhesive force at the initial stage of adhesion tends to be 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 thereof with the crosslinked network to adjust the increase of the adhesive force after mild heating, the amount of the polyfunctional monomer may be 2.0 parts by weight or less, 1.0 parts by weight or less, or 0.5 parts by weight or less with respect to 100 parts by weight of the polymer a.

(tackifying resin)

The adhesive layer may contain a tackifying resin as required. The tackifying resin is not particularly limited, and examples thereof include rosin-based tackifying resins, terpene-based tackifying resins, phenol-based tackifying resins, hydrocarbon-based tackifying resins, ketone-based tackifying resins, polyamide-based tackifying resins, epoxy-based tackifying resins, and elastomer-based tackifying resins. The tackifying resin may be used singly or in combination of two or more.

Examples of the rosin-based tackifying resin include: unmodified rosins (raw rosins) such as gum rosin, wood rosin, tall oil rosin, and the like; modified rosins (polymerized rosins, stabilized rosins, disproportionated rosins, fully hydrogenated rosins, partially hydrogenated rosins, other chemically modified rosins, etc.) obtained by modifying these unmodified rosins by polymerization, disproportionation, hydrogenation, etc.; and rosin derivatives of various kinds in addition to the above.

Examples of the rosin derivatives include:

rosin phenol resins obtained by thermal polymerization of a rosin (unmodified rosin, modified rosin, various rosin derivatives, etc.) with an acid catalyst added thereto;

an ester compound of rosin obtained by esterifying an unmodified rosin with an alcohol (unmodified rosin ester); rosin ester resins such as ester compounds of modified rosins (e.g., polymerized rosin esters, stabilized rosin esters, disproportionated rosin esters, fully hydrogenated rosin esters, and partially hydrogenated rosin esters) obtained by esterifying modified rosins such as polymerized rosins, stabilized rosins, disproportionated rosins, fully hydrogenated rosins, and partially hydrogenated rosins with alcohols;

unsaturated fatty acid-modified rosin-based resins obtained by modifying unmodified rosin or modified rosin (polymerized rosin, stabilized rosin, disproportionated rosin, fully hydrogenated rosin, partially hydrogenated rosin, etc.) with an unsaturated fatty acid;

Unsaturated fatty acid-modified rosin ester resin obtained by modifying rosin ester resin with unsaturated fatty acid;

rosin alcohol resins obtained by reducing carboxyl groups 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;

and metal salts of rosin-based resins (particularly rosin ester-based resins) such as unmodified rosin, modified rosin, and various rosin derivatives.

Examples of the terpene-based tackifying resin include terpene-based resins such as α -pinene polymer, β -pinene polymer and dipentene polymer, and modified terpene-based resins obtained by modifying these terpene-based resins (e.g., phenol-modified, aromatic-modified, hydrogenated-modified, hydrocarbon-modified, etc.), and the like.

Examples of the phenol-based tackifying resin include condensates of various phenols (e.g., phenol, m-cresol, 3, 5-xylenol, p-alkylphenol, resorcinol, etc.) with formaldehyde (e.g., alkylphenol-based resins, xylenol-based resins, etc.), resol resins obtained by an addition reaction of the above-mentioned phenols with formaldehyde using a base catalyst, and novolacs obtained by a condensation reaction of the above-mentioned phenols with formaldehyde using an acid catalyst.

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

Examples of commercially available polymerized rosin esters that can be preferably used include, but are not limited to, those having the trade names "Pensel D-125", "Pensel D-135", "Pensel D-160", "Pensel KK", "Pensel C", and the like, manufactured by the King chemical industries, inc.

Examples of commercially available terpene phenol resins that can be preferably used include, but are not limited to, YASUHARA CHEMICAL co, trade names "YS polymer S-145" manufactured by ltd, YS polymer G-125, YS polymer N125, YS polymer U-115, trade names "Tamanol 803L" manufactured by kawa chemical industry, ltd, trade names "sumitestin PR-12603", and the like.

The content of the tackifying resin is not particularly limited, and may be set so as to exhibit an appropriate adhesive property according to the purpose and use. The content of the tackifying resin (when two or more tackifying resins are included, the total amount of these) may be, for example, about 5 to 500 parts by weight relative to 100 parts by weight of the polymer a.

As the tackifying resin, a tackifying resin having a softening point (softening temperature) of about 80 ℃ or higher (preferably about 100 ℃ or higher, for example, about 120 ℃ or higher) can be preferably used. An adhesive sheet having a high adhesive force after heating can be easily obtained by using a tackifier resin having a softening point of the above lower limit or more. The upper limit of the softening point is not particularly limited, and may be, for example, about 200℃or lower (typically 180℃or lower). The softening point of the tackifying resin can be measured based on the softening point test method (ring and ball method) specified in JIS K2207.

The pressure-sensitive adhesive layer in the technology disclosed herein may contain, if necessary, known additives usable as adhesives such as leveling agents, plasticizers, softeners, colorants (dyes, pigments, etc.), fillers, antistatic agents, antioxidants, ultraviolet absorbers, antioxidants, light stabilizers, and preservatives, within a range that does not significantly hinder the effects of the present invention.

The adhesive layer constituting the adhesive sheet disclosed herein may be a cured layer of the adhesive composition. That is, the adhesive layer can be formed by applying (for example, coating) an adhesive composition such as a water-dispersible, solvent-based, photo-curable, or hot-melt type to an appropriate surface, and then suitably performing a curing treatment. In the case of performing two or more kinds of curing treatments (drying, crosslinking, polymerization, cooling, etc.), these may be performed simultaneously or in multiple stages. For the adhesive composition of a part of the polymer (polymer slurry) using the monomer raw material, it is typical to perform the final copolymerization reaction as the above-mentioned curing treatment. That is, a portion of the polymer is subjected to further copolymerization to form a complete polymer. For example, in the case of a photocurable adhesive composition, light irradiation is performed. If necessary, a curing treatment such as crosslinking and drying may be performed. For example, in the case where the composition is a photocurable adhesive composition and drying is required, it is preferable to carry out photocuring after drying. As for the adhesive composition using the complete polymer, typically, the above-mentioned curing treatment is carried out by drying (heat drying), crosslinking, or the like, as necessary.

The adhesive composition may be applied using a conventional coater such as a gravure roll coater, a reverse roll coater, a roll lick coater, a dip roll coater, a bar coater, a blade coater, or a spray coater.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, and may be 1 μm or more, for example. 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 more than 20 μm. By increasing the thickness of the adhesive layer, the adhesive force tends to increase after heating. In some embodiments, the thickness of the pressure-sensitive adhesive layer may be 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, or 40 μm or less, for example. From the viewpoints of thinning the adhesive sheet, preventing cohesive failure of the adhesive layer, and the like, it is advantageous that the thickness of the adhesive layer is not excessively large. In the case of an adhesive sheet having a first adhesive layer and a second adhesive layer on a first surface and a second surface of a base material, the thickness of the adhesive layer may be applied to at least the thickness of the first adhesive layer. The thickness of the second adhesive layer may also be selected from the same range. In the case of the adhesive sheet without a base material, the thickness of the adhesive sheet corresponds to the thickness of the adhesive layer.

The storage modulus G' (150 ℃) of the pressure-sensitive adhesive layer at 150 ℃ is appropriately set within a range in which the pressure-sensitive adhesive strength rises to a predetermined value or more after mild heating, and is not limited to a specific range. In some embodiments, the storage modulus G' (150 ℃) of the pressure-sensitive adhesive layer may be 5000Pa or more, and from the viewpoint of obtaining good adhesive properties such as low adhesive force at the initial stage of adhesion, it is preferably 10,000Pa or more, more preferably 15,000Pa or more, further preferably 20,000Pa or more (for example, 25,000Pa or more), may be 30,000Pa or more, may be 40,000Pa or more, and may be 50,000Pa or more. The storage modulus G' (150 ℃) may be 300,000Pa or less, 200,000Pa or less, 150,000Pa or less, or 100,000Pa or less, for example. In some preferred embodiments, the storage modulus G' (150 ℃) is 90,000pa or less, may be 70,000pa or less, may be 50,000pa or less, may be 40,000pa or less, or may be 30,000pa or less, from the viewpoint of improving the adhesive force after mild heating, with a good degree of crosslinking that allows for moderate movement of the polymer B within the adhesive layer. The storage modulus G' (150 ℃) of the adhesive layer can be adjusted according to the kind and amount of the crosslinking agent, the molecular weight of the polymer A, the molecular structure, and the like. The storage modulus G' (150 ℃) of the adhesive layer was measured by the method described in examples described below.

The gel fraction of the adhesive constituting the adhesive layer is usually in the range of 20.0% to 99.0%, preferably in the range of 30.0% to 90.0%, but is not particularly limited. By setting the gel fraction to the above range, an increase in adhesive force after mild heating can be satisfactorily achieved. The gel fraction was measured by the following method.

[ measurement of gel fraction ]

With a porous polytetrafluoroethylene film having an average pore diameter of 0.2 μm (weight Wg ₂ ) About 0.1g of the adhesive sample (weight Wg ₁ ) Wrapping in a purse string, and using kite string (weight Wg ₃ ) The mouth is pricked. The porous polytetrafluoroethylene film was prepared by using a product of the trade name "NITOFLON (registered trademark) NTF1122" (average pore size 0.2 μm, porosity 75%, thickness 85 μm, available from niton electric Co., ltd.) or equivalent. The pouch was immersed in 50mL of ethyl acetate and kept at room temperature (typically 23 ℃) for 7 days, whereby the sol component (ethyl acetate-soluble component) in the adhesive was eluted out of the film. Then, the above-mentioned pouch was taken out and ethyl acetate adhering to the outer surface was wiped off, and then the pouch was dried at 130℃for 2 hours, and the weight (Wg ₄ ). By substituting the values into the following formula, the gel fraction G of the adhesive can be calculated _C 。

Gel fraction G _C (％)＝[(Wg ₄ -Wg ₂ -Wg ₃ )/Wg ₁ ]×100

< support substrate >

The pressure-sensitive adhesive sheet of several modes may be in the form of a pressure-sensitive adhesive sheet with a base material having a pressure-sensitive adhesive layer on one or both sides of a support base material. The material of the support base is not particularly limited, and may be appropriately selected depending on the purpose, mode of use, and the like of the adhesive sheet. Non-limiting examples of the usable substrate include polyolefin films containing polyolefin such as polypropylene and ethylene-propylene copolymer as a main component, polyester films containing polyester such as polyethylene terephthalate and polybutylene terephthalate as a main component, and plastic films such as polyvinyl chloride films containing polyvinyl chloride as a main component; foam sheets formed of a foam such as polyurethane foam, polyethylene foam, polychloroprene foam, or the like; woven fabrics and nonwoven fabrics obtained by various fibrous materials (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, semisynthetic fibers such as acetate, etc.) alone or by blending; papers such as japanese paper, high-quality paper, kraft paper, crepe paper, etc.; metal foils such as aluminum foil and copper foil; etc. The substrate may be a composite structure of these. Examples of such a composite substrate include a substrate having a structure in which a metal foil and the plastic film are laminated, a plastic substrate reinforced with inorganic fibers such as glass cloth, and the like.

As the substrate of the adhesive sheet disclosed herein, various film substrates can be preferably used. The film substrate may be porous, such as a foam film or a nonwoven fabric sheet, or may be a non-porous substrate, or may be a substrate having a structure in which a porous layer is laminated with a non-porous layer. In some embodiments, as the film base material, a film base material including a resin film (independent or independent) capable of independently maintaining a shape can be preferably used. The term "resin film" as used herein refers to a resin film of a non-porous structure, typically substantially free of bubbles (void-free). Therefore, the resin film is a concept different from a foam film and a nonwoven fabric. As the resin film, a resin film (free-standing or independent) which can maintain its shape independently can be preferably used. The resin film may have a single-layer structure or a multilayer structure (for example, a three-layer structure) of two or more layers.

As the resin material constituting the resin film, for example, polyamide (PA), polyimide (PI), polyamideimide (PAI), polyether ether ketone (PEEK), polyether sulfone (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyurethane (PU), ethylene-vinyl acetate copolymer (EVA), fluororesin such as Polytetrafluoroethylene (PTFE), acrylic resin, polyacrylate, polystyrene, polyvinyl chloride, polyvinylidene chloride, and the like can be used. The resin film may be formed using a resin material containing one kind of such a resin alone, or may be formed using a resin material obtained by mixing two or more kinds of such resins. The resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).

Examples of suitable resin materials constituting the resin film include polyester resins, PPS resins, and polyolefin resins. The polyester resin herein means a resin containing polyester in an amount exceeding 50% by weight. Similarly, PPS resin means a resin containing PPS in an amount exceeding 50% by weight, and polyolefin resin means a resin containing polyolefin in an amount exceeding 50% by weight.

As the polyester resin, a polyester resin containing a polyester obtained by polycondensing a dicarboxylic acid and a diol as a main component can be typically used.

Examples of the dicarboxylic acid constituting the polyester include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, 2-methyl terephthalic acid, 5-sulfoisophthalic acid, 4' -diphenyldicarboxylic acid, 4' -diphenylether dicarboxylic acid, 4' -diphenylketone dicarboxylic acid, 4' -diphenoxyethane dicarboxylic acid, 4' -diphenylsulfone dicarboxylic acid, 1, 4-naphthalene dicarboxylic acid, 1, 5-naphthalene dicarboxylic acid, 2, 6-naphthalene dicarboxylic acid, and 2, 7-naphthalene dicarboxylic acid; alicyclic dicarboxylic acids such as 1, 2-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid and 1, 4-cyclohexanedicarboxylic acid; aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and dodecanoic acid; unsaturated dicarboxylic acids such as maleic acid, maleic anhydride, fumaric acid, etc.; derivatives thereof (for example, lower alkyl esters of the above dicarboxylic acids such as terephthalic acid, etc.); etc. These may be used singly or in combination of two or more. From the viewpoint of strength and the like, aromatic dicarboxylic acids are preferable. Among these, terephthalic acid and 2, 6-naphthalene dicarboxylic acid are preferable. For example, 50 wt% or more (for example, 80 wt% or more, typically 95 wt% or more) of the dicarboxylic acids constituting the polyester is preferably terephthalic acid, 2, 6-naphthalene dicarboxylic acid or a combination thereof. The dicarboxylic acid may be composed substantially of only terephthalic acid, substantially of only 2, 6-naphthalene dicarboxylic acid, or substantially of only terephthalic acid and 2, 6-naphthalene dicarboxylic acid.

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

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

As the polyolefin resin, one polyolefin may be used alone, or two or more polyolefins may be used in combination. The polyolefin may be, for example, a homopolymer of an α -olefin, a copolymer of two or more α -olefins, a copolymer of one or more α -olefins and other vinyl monomers, or the like. Specific examples thereof include ethylene-propylene copolymers such as Polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, and ethylene-propylene rubber (EPR), ethylene-propylene-butene copolymers, ethylene-vinyl alcohol copolymers, and ethylene-ethyl acrylate copolymers. Any of Low Density (LD) polyolefin and High Density (HD) polyolefin may be used. Examples of the polyolefin resin film include an unstretched polypropylene (CPP) film, a biaxially oriented polypropylene (OPP) film, a Low Density Polyethylene (LDPE) film, a Linear Low Density Polyethylene (LLDPE) film, a Medium Density Polyethylene (MDPE) film, a High Density Polyethylene (HDPE) film, a Polyethylene (PE) film obtained by mixing two or more Polyethylenes (PE), and a PP/PE mixed film obtained by mixing polypropylene (PP) and Polyethylene (PE).

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 viewpoints of strength and dimensional stability include PET films, PEN films, PPS films, and PEEK films. From the viewpoint of ease of obtaining a base material, a PET film and a PPS film are particularly preferable, and a PET film is particularly preferable.

The resin film may be blended with known additives such as a light stabilizer, an antioxidant, an antistatic agent, a colorant (dye, pigment, etc.), a filler, a slip agent, an antiblocking agent, etc., as necessary, within a range that does not significantly impair the effects of the present invention. The blending amount of the additive is not particularly limited, and may be appropriately set according to the use of the adhesive sheet or the like.

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

The substrate may be a substrate consisting essentially of such a base film. Alternatively, the substrate may be a substrate including an auxiliary layer in addition to the base film. Examples of the auxiliary layer include an optical property adjusting layer (e.g., a coloring layer or an antireflection layer), a printed layer or a laminate layer for imparting a desired appearance to a substrate, an antistatic layer, an undercoat layer, a release layer, and other surface treatment layers.

The thickness of the base material is not particularly limited, and may be selected according to the purpose of use, the mode of use, and the like of the adhesive sheet. The thickness of the base material may be 1000 μm or less, for example. In some embodiments, the thickness of the base material may be, for example, 500 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less from the viewpoint of the handleability and workability of the adhesive sheet. From the viewpoint of downsizing and weight reduction of a product to which the pressure-sensitive adhesive sheet is applied, in several embodiments, the thickness of the base material may be 160 μm or less, 130 μm or less, 100 μm or less, 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, for example. When the thickness of the base material is reduced, the flexibility of the pressure-sensitive adhesive sheet and the following property to the surface shape of the adherend tend to be improved. From the viewpoint of handling properties, processability, etc., the thickness of the substrate 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 more than 25 μm. 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, or 120 μm or more. For example, a base material having a thickness of 30 μm or more can be preferably used for an adhesive sheet which can be used for the purpose of reinforcing, supporting, and impact alleviation of an adherend.

The first surface of the substrate may be subjected to conventionally known surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and formation of an undercoat layer by application of a primer (primer), as required. Such a surface treatment may be a treatment for improving the anchoring property of the adhesive layer to the substrate. For example, in an adhesive sheet having a base material including a resin film as a base film, a base material subjected to the above-mentioned anchoring property improving treatment can be preferably used. The above surface treatments may be used alone or in combination. The composition of the primer used for forming the undercoat layer is not particularly limited, and may be appropriately selected from known primers. The thickness of the undercoat layer is not particularly limited, and is usually about 0.01 μm to 1. Mu.m, preferably about 0.1 μm to 1. Mu.m. Examples of other treatments that may be applied to the first surface of the substrate as needed include antistatic layer formation treatment, coloring layer formation treatment, printing treatment, and the like.

In the case where the pressure-sensitive adhesive sheet disclosed herein is in the form of a single-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on only a first side of a substrate, a conventionally known surface treatment such as a peeling treatment or an antistatic treatment may be applied to a second side of the substrate as required. For example, by surface-treating the back surface of the base material with a release agent (typically, by providing a release layer based on the release agent), the unwinding force of the adhesive sheet wound into a roll can be reduced. As the release treatment agent, silicone release treatment agents, long-chain alkyl release treatment agents, olefin release treatment agents, fluorine release treatment agents, fatty acid amide release treatment agents, molybdenum sulfide, silica powder, and the like can be used. In addition, for the purpose of improving printability, reducing light reflectivity, improving re-adhesion, etc., the second surface of the substrate may be subjected to a treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, etc. In the case of the double-sided pressure-sensitive adhesive sheet, the second surface of the base material may be subjected to the same surface treatment as that described above as the surface treatment that can be performed on the first surface of the base material, if necessary. The surface treatment applied to the first surface of the substrate may be the same as or different from the surface treatment applied to the second surface.

< adhesive sheet >

(Properties of adhesive sheet, etc.)

The adhesive sheet disclosed herein can exhibit an adhesive force N of 5N/25mm or more ₅₀ I.e., adhesion force measured at 23 c after adhering to a stainless steel plate and holding at 50 c for 15 minutes. After the adhesive sheet satisfying this characteristic is attached to an adherend, the adhesive force is increased to a predetermined value or more by mild heating at about 50 ℃. According to the technology disclosed herein, a strong adhesive force can be obtained by mild heating, and thus the adhesive force N can be obtained ₅₀ The length is 7N/25mm or more, and for example, 10N/25mm or more, further 13N/25mm or more, 15N/25mm or more, 17N/25mm or more, 19N/25mm or more, 21N/25mm or more, and 23N/25mm or more (for example, 25N/25mm or more) can be used. Adhesive force N ₅₀ The upper limit of (2) is not particularly limited. From the viewpoint of ease of production and economy of the adhesive sheet, the adhesive force N is in several modes ₅₀ For example, the thickness may be 70N/25mm or less, 50N/25mm or less, or 40N/25mm or less.

Adhesive force N measured after being adhered to stainless steel plate and kept at 23 ℃ for 30 minutes ₂₃ In several modes, the adhesive force N is not particularly limited ₂₃ For exampleIt may be 3N/25mm or less, preferably 2.5N/25mm or less, more preferably less than 2N/25mm, may be 1.5N/25mm or less, may be 1.2N/25mm or less, and may be 1N/25mm or less. Adhesive force N is preferred from the viewpoint of reworkability ₂₃ Lower. Adhesive force N ₂₃ The lower limit of (2) is not particularly limited, and may be, for example, 0.01N/25mm or more. From the viewpoints of workability of adhesion to an adherend, prevention of positional displacement before the adhesive force rises, and the like, the adhesive force N ₂₃ Generally 0.1N/25mm or more is suitable. From the viewpoint of improving the adhesive force after heating, etc., in several modes, the adhesive force N ₂₃ For example, the length may be 0.2N/25mm or more, 0.5N/25mm or more, 0.8N/25mm or more, or 1.0N/25mm or more (for example, 1.5N/25mm or more).

Adhesive force N measured at 23℃after being adhered to stainless steel plate and kept at 80℃for 5 minutes ₈₀ In several modes, the adhesive force N is not particularly limited ₈₀ For example, the length may be 5N/25mm or more, 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, or 30N/25mm or more (for example, 35N/25mm or more). In addition, from the viewpoint of ease of production and economy of the adhesive sheet, the adhesive force N is in several modes ₈₀ For example, the thickness may be 70N/25mm or less, 50N/25mm or less, or 40N/25mm or less.

Adhesive force N ₅₀ [N/25mm]Relative to the adhesive force N ₂₃ [N/25mm]The ratio of (2), i.e. the adhesive force rising ratio N ₅₀ /N ₂₃ In several modes, N is not particularly limited ₅₀ /N ₂₃ It is preferably 2 or more (for example, 3 or more), more preferably 5 or more, still more preferably 8 or more, and it may be 10 or more, 12 or more, 15 or more, 18 or more, or 20 or more. By N ₅₀ /N ₂₃ The large pressure-sensitive adhesive sheet can exhibit good reworkability at the initial stage of application, and the adhesive force can be greatly increased by subsequent heating or the like. N (N) ₅₀ /N ₂₃ The upper limit of (2) is not particularly limited, but is usually 100 or less, may be 80 or less, may be 60 or less, or may be 50 or less, from the viewpoint of ease of production and economy of the adhesive sheetFrom the standpoint, it is typically 30 or less, but may be 20 or less. In several ways, N ₅₀ /N ₂₃ For example, the content may be 18 or less, 15 or less, or 12 or less.

Adhesive force N ₈₀ [N/25mm]Relative to the adhesive force N ₅₀ [N/25mm]The ratio of (2), i.e. the adhesive force rising ratio N ₈₀ /N ₅₀ In several modes, N is not particularly limited ₈₀ /N ₅₀ The ratio is preferably 3 or less, more preferably 2 or less, for example, 1.8 or less, and may be 1.5 or less (for example, 1.3 or less). With the adhesive sheet satisfying such characteristics, the adhesive force can be sufficiently increased by mild heating at about 50 ℃, and exposure to further high temperature (specifically, heating at about 80 ℃) is not required to obtain a desired adhesive force. N (N) ₈₀ /N ₅₀ The lower limit of (2) is not particularly limited, and may be, for example, 1 or more, 1.2 or more, 1.4 or more, or 1.6 or more in several embodiments from the viewpoint of ease of production and economy of the pressure-sensitive adhesive sheet.

Here, adhesive force N ₂₃ [N/25mm]The following holds: after being pressed against a stainless steel (SUS) plate as an adherend and left to stand in an environment of 23 ℃ and 50% rh for 30 minutes, 180 ° peel adhesion was measured under the conditions of 180 ° peel angle and 300 mm/min tensile speed in the environment (i.e., at 23 ℃).

Adhesive force N ₅₀ [N/25mm]The following holds: after being held in pressure contact with an SUS plate as an adherend at 50℃for 15 minutes and then allowed to stand at 23℃for 30 minutes in a 50% RH atmosphere, 180℃peel adhesion was measured under the conditions of a peel angle of 180℃and a tensile speed of 300 mm/min.

Adhesive force N ₈₀ [N/25mm]The following holds: after being pressed against an SUS plate as an adherend and heated at 80℃for 5 minutes, and then allowed to stand at 23℃for 30 minutes in an atmosphere of 50% RH, 180℃peel adhesion was measured under the conditions of a peel angle of 180℃and a tensile speed of 300 mm/min.

As an adherend, in the adhesive force N ₂₃ 、N ₅₀ 、N ₈₀ SUS304BA plate was used in any of the assays. At the time of measurement The pressure-sensitive adhesive sheet to be measured may be reinforced by attaching an appropriate backing material (for example, a PET film having a thickness of about 25 μm) thereto as needed. Adhesive force N ₂₃ 、N ₅₀ 、N ₈₀ More specifically, the measurement can be performed according to the method described in the following examples.

The adhesive force after heating of the adhesive sheet disclosed herein indicates one characteristic of the adhesive sheet, and the manner of use of the adhesive sheet is not limited. In other words, the method of using the pressure-sensitive adhesive sheet disclosed herein is not limited to the method of heating at 50℃for 15 minutes, and may be used without intentionally heating to a room temperature region (usually 20 to 30℃and typically 23 to 25 ℃). In this manner of use, the adhesive force can be increased for a long period of time, and a firm joint can be achieved. Further, the adhesive sheet disclosed herein can promote an increase in adhesive force by performing heat treatment at a temperature exceeding 30 ℃ (e.g., 50 ℃) or higher than 50 ℃ at any time after attachment. The heating temperature in the heating treatment is not particularly limited, and may be set in consideration of workability, economy, heat resistance of the base material of the adhesive sheet, the adherend, and the like. The heating temperature may be, for example, less than 150 ℃, 120 ℃ or less, 100 ℃ or less, 80 ℃ or less, or 70 ℃ or less. The heating temperature may be, for example, 40℃or higher, 45℃or higher, 50℃or higher, 55℃or higher, 60℃or higher, or 70℃or higher, and may be 80℃or higher, or 100℃or higher. 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 more, 3 minutes or more, 7 minutes or more, or 15 minutes or more. Alternatively, the heat treatment may be performed for a longer period of time within the limits that the adhesive sheet and the adherend are not significantly thermally degraded. The heat treatment may be performed at one time or may be performed a plurality of times.

(pressure-sensitive adhesive sheet with substrate)

In the case where 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 1000 μm or less, 600 μm or less, 350 μm or less, or 250 μm or less, for example. In some aspects, the thickness of the pressure-sensitive adhesive sheet may be, for example, 200 μm or less, 175 μm or less, 140 μm or less, 120 μm or less, or 100 μm or less (for example, less than 100 μm) from the viewpoint of downsizing, weight saving, thinning, etc. of a product to which the pressure-sensitive adhesive sheet is applied. From the viewpoint of handling properties, 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 refers to the thickness of the portion to be attached to the adherend. For example, the pressure-sensitive adhesive sheet 1 having the structure shown in fig. 1 is 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 adhesive sheet disclosed herein may be suitably implemented in such a manner that, for example, the thickness Ts of the support substrate is greater than the thickness Ta of the adhesive layer, i.e., ts/Ta is greater 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. For example, in an adhesive sheet that can be used for the purpose of reinforcing, supporting, and impact alleviation of an adherend, a favorable effect tends to be easily exhibited even if the adhesive sheet is thinned by increasing Ts/Ta. In several modes, ts/Ta may be 2 or more (e.g., greater than 2), may be 2.5 or more, or may be 2.8 or more. The ratio of Ts/Ta may be 50 or less, or 20 or less, for example. From the viewpoint of easily exhibiting high adhesion after heating even when the pressure-sensitive adhesive sheet is thinned, ts/Ta may be, for example, 10 or less, 8 or less, or 5 or less.

The adhesive layer is preferably fixed to the support base material. The term "anchoring" as used herein means: in the adhesive sheet having an increased adhesive force after attachment to an adherend, sufficient anchoring properties of the adhesive layer to the support substrate are exhibited to such an extent that peeling at the interface of the adhesive layer and the support substrate does not occur when the adhesive sheet is peeled from the adherend. When the pressure-sensitive adhesive sheet with a base material is fixed to a support base material with the pressure-sensitive adhesive layer, the adherend and the support base material can be firmly integrated. As a preferable example of the adhesive sheet in which the adhesive layer is fixed to the substrate, there is an adhesive sheet in which peeling (anchor failure) does not occur between the adhesive layer and the supporting substrate at the time of measurement of the adhesive force after heating. An adhesive sheet having a post-heat adhesive strength of 15N/25mm or more and not causing anchor failure when the post-heat adhesive strength is measured is a preferable example of an adhesive sheet having an adhesive layer fixed to a substrate.

The adhesive sheet disclosed herein can be preferably manufactured by, for example, a method comprising the following steps in order: the adhesive layer is formed by bringing a liquid adhesive composition into contact with a first surface of a substrate and curing the adhesive composition on the first surface. The curing of the adhesive composition may be accompanied by one or more of drying, crosslinking, polymerization, cooling, and the like of the adhesive composition. By the method of forming the adhesive layer by curing the liquid adhesive composition on the first surface of the substrate in this way, the anchoring property of the adhesive layer to the substrate can be improved as compared with a method of disposing the adhesive layer on the first surface of the substrate by bonding the cured adhesive layer to the first surface. With this, an adhesive sheet having an adhesive layer fixed to a base material can be produced satisfactorily.

In some embodiments, as a method of bringing the liquid adhesive composition into contact with the first surface of the substrate, a method of directly applying the adhesive composition to the first surface of the substrate may be employed. By bringing the first surface (adhesive surface) of the adhesive layer cured on the first surface of the base material into contact with the release surface, it is possible to obtain an adhesive sheet in which the second surface of the adhesive layer is fixed to the first surface of the base material and the first surface of the adhesive layer is brought into contact with the release surface. The release surface may be a surface of a release liner, a back surface of a substrate subjected to a release treatment, or the like.

In the case of a photocurable adhesive composition using a partial polymer (polymer slurry) of a monomer material, for example, the adhesive composition may be applied to a release surface, and then the first surface of a substrate may be covered with the applied adhesive composition, whereby the uncured adhesive composition is brought into contact with the first surface of the substrate, and in this state, the adhesive composition sandwiched between the first surface of the substrate and the release surface may be irradiated with light to be cured, thereby forming an adhesive layer.

The method exemplified above is not limited to the method for producing the pressure-sensitive adhesive sheet disclosed herein. In the production of the adhesive sheet disclosed herein, two or more suitable methods for fixing the adhesive layer to the first surface of the substrate may be used singly or in combination. Examples of such methods include: as described above, the method of forming the adhesive layer by curing the liquid adhesive composition on the first surface of the substrate includes a method of performing a surface treatment for improving the anchoring property of the adhesive layer on the first surface of the substrate. For example, when the anchoring property of the adhesive layer to the substrate can be sufficiently improved by providing a primer layer or the like on the first surface of the substrate, the adhesive sheet can be produced by a method of bonding the cured adhesive layer to the first surface of the substrate. In addition, the anchoring property of the adhesive layer to the substrate can be improved by selecting the material of the substrate and selecting the composition of the adhesive. In addition, by applying a temperature higher than room temperature to the adhesive sheet having the adhesive layer on the first surface of the substrate, the anchoring property of the adhesive layer to the substrate can be improved. The temperature used for improving the anchoring property may be, for example, about 35 to 80 ℃, about 40 to 70 ℃ or more, or about 45 to 60 ℃.

In the case where the pressure-sensitive adhesive sheet disclosed herein is in the form of a pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive layer provided on a first surface of a substrate and a second pressure-sensitive adhesive layer provided on a second surface of the substrate (i.e., a pressure-sensitive adhesive sheet with a substrate having double-sided adhesiveness), the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may have the same or different structures. When the first adhesive layer and the second adhesive layer are different in composition, the difference may be, for example, a difference in composition or a junctionDifferences in texture (thickness, surface roughness, formation range, patterning, etc.). For example, the second adhesive layer may be an adhesive layer that does not contain polymer B. In addition, the adhesive force N of the surface (second adhesive surface) of the second adhesive layer ₅₀ May be less than 5N/25mm, may be less than 3N/25mm, may be less than 1.5N/25mm, and may be less than 1N/25mm.

< pressure-sensitive adhesive sheet with Release liner >

The pressure-sensitive adhesive sheet disclosed herein may be in the form of a pressure-sensitive adhesive product in which the surface (pressure-sensitive adhesive surface) of the pressure-sensitive adhesive layer is brought into contact with the release surface of the release liner. Therefore, according to the present specification, a release liner-attached adhesive sheet (adhesive product) including any of the adhesive sheets disclosed herein and a release liner having a release surface that abuts against the adhesive surface of the adhesive sheet can be provided.

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, the adhesion to the adhesive layer and the release from the adhesive layer are excellent, and thus are preferable. In some embodiments, the release liner may have a thickness of, for example, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. In addition, from the viewpoint of facilitating the peeling of the self-adhesive layer, the thickness of the release liner may be, for example, 100 μm or less, or 80 μm or less. The release liner may be subjected to known antistatic treatments such as a coating type, a kneading type, and a vapor deposition type, as necessary.

The release liner is not particularly limited, and for example, a release liner having a release layer on the surface of a liner substrate such as a resin film or paper (paper laminated with a resin such as polyethylene), a release liner containing a resin film made of a low-adhesion material such as a fluorine-based polymer (polytetrafluoroethylene or the like) or a polyolefin-based resin (polyethylene, polypropylene or the like), or the like can be used. From the viewpoint of excellent surface smoothness, a release liner having a release layer on the surface of a resin film as a liner base material, and a release liner comprising a resin film formed of a low-adhesion material can be preferably used. The resin film is not particularly limited as long as it is a film capable of protecting the pressure-sensitive adhesive layer, and examples thereof include polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyester film (PET film, PBT film, etc.), polyurethane film, ethylene-vinyl acetate copolymer film, etc. For forming the release layer, for example, a known release agent such as a silicone release agent, a long-chain alkyl release agent, an olefin release agent, a fluorine release agent, a fatty acid amide release agent, molybdenum sulfide, or silica powder can be used. The use of a silicone release treating agent is particularly preferred.

The thickness of the release layer is not particularly limited, and is usually about 0.01 μm to 1. Mu.m, preferably about 0.1 μm to 1. Mu.m. The method of forming the release layer is not particularly limited, and a known method may be suitably used depending on the kind of the release treatment agent used and the like.

< usage >

The pressure-sensitive adhesive sheet provided in the present specification can exhibit good reworkability at the initial stage of bonding to an adherend, for example, and thus can contribute to suppression of reduction in yield and realization of high quality of a product including the pressure-sensitive adhesive sheet. The adhesive sheet can be cured (which may be a mild heat at around 50 ℃ C., a long time, a combination thereof, or the like) to greatly increase the adhesive force. For example, by heating at a desired timing, the adhesive sheet can be firmly adhered to the adherend. With this feature, the adhesive sheet disclosed herein can be preferably used in various fields for the purpose of fixing, joining, shaping, decorating, protecting, reinforcing, supporting, impact alleviation, and the like of members contained in various products.

The pressure-sensitive adhesive sheet disclosed herein may be used, for example, in the form of a pressure-sensitive adhesive sheet with a base material having a film-like base material having a first surface and a second surface and an adhesive layer provided on at least the first surface, as a reinforcing film to be attached to an adherend to reinforce the adherend. In the reinforcing film, a film base material including a resin film as a base film is preferably used as the film base material. In addition, from the viewpoint of improving the reinforcing performance, the pressure-sensitive adhesive layer is preferably fixed to the first surface of the film-like base material.

For example, in an optical member used in an optical product and an electronic member used in an electronic product, there is a possibility that a plurality of thin optical members/electronic members having different linear expansion coefficients and thicknesses may be stacked in a highly integrated manner, a small size, a light weight, and a thin profile. By attaching the reinforcing film to such a member, appropriate rigidity can be imparted to the optical member and the electronic member. Thus, the curling and bending due to the stress that may occur between the plurality of members having different linear expansion coefficients and different thicknesses can be suppressed in the manufacturing process and/or the manufactured product.

In addition, in the manufacturing process of the optical product/electronic product, in terms of performing shape processing such as cutting processing on the thin optical member/electronic member, the strong film is attached to the member for processing, so that local stress concentration on the optical member/electronic member accompanying processing can be relaxed, and risks such as cracks, breakage, and peeling of the laminated member can be reduced. The process of attaching the reinforcing member to the optical member/electronic member can also help to alleviate local stress concentration in transportation, lamination, rotation, and the like of the member, suppress bending, and the like caused by the self weight of the member.

Further, even in the case where a device such as an optical product or an electronic product including the reinforcing film is unintentionally applied with stress in the case where the device falls down, is placed under a heavy object, is bumped by a flying object, or the like, the pressure applied to the device can be relaxed by including the reinforcing film in the device in the stage where the device is used by consumers in the market. Therefore, by incorporating the reinforcing film into the above device, the durability of the device can be improved.

The pressure-sensitive adhesive sheet disclosed herein can be preferably used, for example, by being attached to members constituting various portable devices (portable equipment). The term "portable" is merely to be construed as being insufficient to be portable, which means to have a level of portability that an individual (standard adult) can relatively easily carry. Examples of the portable device include mobile phones, smart phones, tablet personal computers, notebook personal computers, various wearable devices, digital cameras, digital video cameras, audio devices (portable music players, IC recorders, etc.), calculators (desktop calculators), portable game devices, electronic dictionaries, electronic notepads, electronic books, in-vehicle information devices, portable radios, portable televisions, portable printers, portable scanners, portable electronic devices such as modems, mechanical wristwatches, pocket watches, flashlights, and hand mirrors. Examples of the members constituting the portable electronic device include a thin-layer display such as a liquid crystal display, an optical film used in an image display device such as a film-type display, a display panel, and the like. The pressure-sensitive adhesive sheet disclosed herein can be preferably used as being attached to various members in automobiles, home electric appliances, and the like.

Examples

The following describes several embodiments related to the present invention, but is not intended to limit the present invention to those shown in the specific examples. In the following description, "parts" and "%" refer to weight unless otherwise specified.

(preparation of Polymer A1)

To a reaction vessel equipped with a stirring blade, a thermometer, a nitrogen inlet pipe, and a condenser, 60 parts of 2-ethylhexyl acrylate (2 EHA), 15 parts of N-vinyl-2-pyrrolidone (NVP), 10 parts of Methyl Methacrylate (MMA), 15 parts of 2-hydroxyethyl acrylate (HEA), and 200 parts of ethyl acetate as a polymerization solvent were added, and after stirring at 60 ℃ for 2 hours under a nitrogen atmosphere, 0.2 part of 2,2' -Azobisisobutyronitrile (AIBN) was charged as a thermal polymerization initiator, and a reaction was performed at 60 ℃ for 6 hours to obtain a solution of polymer A1. The Mw of the polymer A1 was 110 million.

(preparation of Polymer B1)

Into a reaction vessel equipped with stirring blades, a thermometer, a nitrogen inlet pipe and a condenser, 40 parts of MMA, 20 parts of n-Butyl Methacrylate (BMA), 20 parts of 2-ethylhexyl methacrylate (2 EHMA) and a polyorganosiloxane-skeleton-containing methacrylate monomer (trade name: X-22- 174ASX, believed to be a product of the company chemical industry, inc.) 8.7 parts of a polyorganosiloxane-skeleton-containing methacrylate monomer (trade name: KF-2012, manufactured by Xinyue chemical industries Co., ltd.) 11.3 parts, ethyl acetate 100 parts, and thioglycerol 0.5 parts as a chain transfer agent, stirred at 70℃for 1 hour under a nitrogen atmosphere, then charged with 0.2 parts of AIBN as a thermal polymerization initiator, reacted at 70℃for 2 hours, then charged with 0.1 parts by weight of AIBN as a thermal polymerization initiator, and reacted at 80℃for 5 hours. Thus, a solution of the polymer B1 was obtained. The Mw of the polymer B1 was 2.2X10 ⁴ 。

(preparation of Polymer B2)

Mw of 16.5X10 was obtained in the same manner as in the preparation of Polymer B1 except that thioglycerol was not used ⁴ Polymer B2 of (a).

The weight average molecular weight of each polymer was measured using a GPC apparatus (manufactured by Tosoh Co., ltd., HLC-8220 GPC) under the following conditions, and was obtained by conversion into polystyrene.

GPC conditions ]

Sample concentration: 0.2wt% (tetrahydrofuran (THF)) solution

Sample injection amount: 10 μl of

Eluent: THF-flow rate: 0.6 ml/min

Measurement temperature: 40 DEG C

Column:

a sample column; TSKguardcolumn SuperHZ-H (1 root) +TSKgel SuperHZM-H (2 roots)

A reference column; TSKgel SuperH-RC (1 root)

Detector: differential Refractometer (RI)

< production of adhesive sheet >

Example 1

To 100 parts of the polymer A1 contained in the solution were added 2 parts of the polymer B1 and 0.5 part of an isocyanate-based crosslinking agent (trade name: takenate D110N, trimethylol propane xylylene diisocyanate, manufactured by Mitsui chemical Co., ltd.) and the mixture was uniformly mixed to prepare an adhesive composition C1.

An adhesive composition C1 was directly applied to a first surface of a polyethylene terephthalate (PET) film (trade name "Lumiror" manufactured by Toray Co., ltd.) having a thickness of 75 μm as a supporting substrate, and heated at 110℃for 2 minutes to dry, thereby forming an adhesive layer having a thickness of 15. Mu.m. The release surface of the release liner is bonded to the surface (adhesive surface) of the adhesive layer. As the release liner, MRQ25T100 (release liner having a release layer formed by a silicone release agent on one side of a polyester film, thickness 25 μm) manufactured by mitsubishi chemical company was used. Thus, the pressure-sensitive adhesive sheet of example 1 was obtained as a pressure-sensitive adhesive sheet with a release liner in which the release surface of the release liner was in contact with the pressure-sensitive adhesive surface.

(examples 2 to 4)

Adhesive compositions C2 to C4 were prepared in the same manner as in the preparation of adhesive composition C1 except that the type of polymer B or the amount of the crosslinking agent was changed as shown in table 1. The adhesive sheets of examples 2 to 4 were obtained as release liner-attached adhesive sheets having a release liner with its release surface in contact with its adhesive surface, in the same manner as in the production of the adhesive sheet of example 1, except that these adhesive compositions C2 to C4 were used, respectively.

< storage modulus G' (150 ℃ C.) >

The storage modulus G' (150 ℃) of the adhesive layer was determined by dynamic viscoelasticity measurement. Specifically, an adhesive layer was formed on the release surface of the release liner instead of the PET film, and the adhesive layer was formed under substantially the same conditions as in each example, and the adhesive layers were stacked in a plurality of layers, thereby forming an adhesive layer having a thickness of about 2 mm. The obtained adhesive layer was punched into a disk shape having a diameter of 7.9mm to obtain a sample, the sample was held and fixed by a parallel plate, and dynamic viscoelasticity was measured by a viscoelasticity tester (for example, "ARES" manufactured by TA Instruments, or equivalent thereof) under the following conditions to obtain a storage modulus G' (150 ℃). The pressure-sensitive adhesive layer to be measured may be formed by applying the corresponding pressure-sensitive adhesive composition in a layer form to a release surface of a release liner or the like, and drying or curing the composition.

Measurement mode: shear mode

Temperature range: -50-200 DEG C

Temperature increase rate: 5 ℃/min

Measurement frequency: 1Hz

< determination of adhesion (23 ℃ C.) >)

The adhesive sheets of each example were cut into a width of 25mm together with a release liner, and the adhesive force N was measured in the following order using a SUS plate (SUS 304BA plate) cleaned with toluene as an adherend as a test piece ₂₃ Adhesive force N ₅₀ Adhesive force N ₈₀ 。

(adhesive force N) ₂₃ Is to be determined by (a) and (b) is to be determined by (b) a measurement of

The release liner covering the adhesive surface of each test piece was peeled off under a standard atmosphere of 50% RH at 23℃and a 2kg roller was reciprocated 1 time to press the exposed adhesive surface against the adherend. After the test piece thus pressure-bonded to the adherend was left under the above standard environment for 30 minutes, 180 ° peel adhesion (resistance to the above stretching) was measured under conditions of a peel angle of 180 degrees and a stretching speed of 300 mm/minute in accordance with JIS Z0237 using a universal tensile compression tester (device name "tensile compression tester, TCM-1knb" manufactured by minebea). The measurement was performed 3 times, and the average value thereof was regarded as the adhesive force N ₂₃ [N/25mm]Shown in Table 1.

(adhesive force N) ₅₀ Is to be determined by (a) and (b) is to be determined by (b) a measurement of

Will pass through the adhesive force N ₂₃ The test piece pressed against the adherend in the same manner was held at 50℃for 15 minutes, then left to stand in the above-mentioned standard environment for 30 minutes, and thereafter 180℃peel adhesion was measured in the same manner. The measurement was performed 3 times, and the average value thereof was regarded as the adhesive force N ₅₀ [N/25mm]Shown in Table 1.

(adhesive force N) ₈₀ Is to be determined by (a) and (b) is to be determined by (b) a measurement of

Will pass through the adhesive force N ₂₃ The test piece pressed against the adherend in the same manner was heated at 80℃for 5 minutes, then left to stand in the above-mentioned standard environment for 30 minutes, and thereafter 180℃peel adhesion was measured in the same manner. The measurement was performed 3 times, and the average value thereof was regarded as the adhesive force N ₈₀ [N/25mm]Shown in Table 1. The adhesive sheets of examples 1 to 4 were confirmed to have adhesive strength N ₈₀ No anchor failure occurred at all.

Based on these adhesive force measurement results, the adhesive force increase ratio N was calculated ₈₀ /N ₅₀ N ₅₀ /N ₂₃ . The results are shown in Table 1.

TABLE 1

As shown in Table 1, the adhesive sheets of examples 1 to 4 each have an adhesive layer comprising a polymer A and a polymer B, wherein the polymer B is a copolymer of a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer, and the adhesive sheets of examples 1 to 4 each have an adhesive force N of 5N/25mm or more ₅₀ . These adhesive sheets are known to exhibit excellent reworkability at the initial stage of application, and thereafter, the adhesive strength can be increased to a predetermined value or more by mild heating at about 50 ℃. In examples 1 to 3, in which an adhesive layer having a storage modulus G' (150 ℃) of 10,000Pa or more and 90,000Pa or less at 150℃was used, particularly good results were obtained. Specifically, the adhesive force N at the initial stage of the attachment ₂₃ Further improving the adhesive force N while suppressing it to be low ₅₀ 。

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of protection of the claims. The technology described in the claims includes various modifications and changes to the specific examples described above.

Description of the reference numerals

1,2,3 adhesive sheet

10. Support substrate

10A first side

10B second side

21. Adhesive layer (first adhesive layer)

21A adhesive surface (first adhesive surface)

21B adhesive surface (second adhesive surface)

22. Adhesive layer (second adhesive layer)

22A adhesive side (second adhesive side)

31 32 release liner

100 200, 300 pressure-sensitive adhesive sheet with release liner (pressure-sensitive adhesive product)

Claims

1. An adhesive sheet comprising an adhesive layer,

the adhesive layer comprises a polymer A and a polymer B, wherein the polymer B is a copolymer of a (methyl) acrylic monomer and a monomer with a polyorganosiloxane framework,

the adhesive sheet was adhered to a stainless steel plate and held at 50℃for 15 minutes, and then measured for adhesive force N at 23 ℃ ₅₀ Is more than 23N/25mm,

the adhesive force N ₅₀ With respect to the adhesive force N measured after being adhered to the stainless steel plate and kept at 23℃for 30 minutes ₂₃ Ratio (N) ₅₀ /N ₂₃ ) Is not more than 12 and is not more than 12,

adhesive force N ₈₀ Relative to the adhesive force N ₅₀ Ratio (N) ₈₀ /N ₅₀ ) 1.5 or less, wherein the adhesive force N ₈₀ Adhesive force N measured at 23℃after being adhered to stainless steel plate and kept at 80℃for 5 minutes ₈₀ ，

The adhesive layer has a storage modulus G' (150 ℃) of 10,000Pa or more and 50,000Pa or less at 150 ℃.

2. The adhesive sheet according to claim 1, wherein the adhesive force N ₂₃ Is 3N/25mm or less.

3. The adhesive sheet according to claim 1 or 2, wherein the adhesive force N ₅₀ Adhesive force N measured after being adhered to stainless steel plate and kept at 23 ℃ for 30 minutes ₂₃ More than 5 times of the total number of the components.

4. The adhesive sheet according to any one of claims 1 to 3, wherein the polymer a contained in the adhesive layer is chemically crosslinked.

5. The adhesive sheet according to any one of claims 1 to 4, wherein the weight average molecular weight of the polymer B is 100,000 or more.

6. The adhesive sheet according to any one of claims 1 to 4, wherein the weight average molecular weight of the polymer B is less than 80,000.

7. The adhesive sheet according to any one of claims 1 to 6, wherein the content of the polymer B in the 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.

8. The adhesive sheet according to any one of claims 1 to 7, wherein the polymer a is an acrylic polymer.

9. The adhesive sheet according to claim 8, wherein the acrylic polymer contains a monomer having a nitrogen atom-containing ring as its monomer unit.

10. The adhesive sheet according to any one of claims 1 to 9, wherein the monomer component for preparing the polymer B contains, as the (meth) acrylic monomer, a monomer having a homopolymer glass transition temperature of 50 ℃ or higher at a ratio of 60% by weight or less.

11. The adhesive sheet according to any one of claims 1 to 10, which comprises a support substrate having a first surface and a second surface, wherein the adhesive layer is laminated on at least the first surface of the support substrate.

12. An adhesive sheet comprising an adhesive layer,

the adhesive layer has a storage modulus G' (150 ℃) of 10,000Pa or more and 50,000Pa or less at 150 ℃,

adhesive force N ₅₀ With respect to the adhesive force N measured after being adhered to the stainless steel plate and kept at 23℃for 30 minutes ₂₃ Ratio (N) ₅₀ /N ₂₃ ) Is 12 or less, wherein the adhesive force N ₅₀ Adhesive force N measured at 23℃after being adhered to stainless steel plate and kept at 50℃for 15 minutes ₅₀ ，

The adhesive sheet was adhered to a stainless steel plate and held at 50℃for 15 minutes, and then measured for adhesive force N at 23 ℃ ₅₀ Is more than 23N/25 mm.