CN113166600B - Adhesive sheet - Google Patents

Abstract

The invention provides an adhesive sheet comprising an adhesive layer. The adhesive layer contains: a polymer A which is a polymer of a monomer raw material A; and a polymer B which is a polymer of a monomer raw material B containing a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer. Mw of the above-mentioned polymer B was 7X 10 ⁴ As described above. The adhesive sheet was adhered to a stainless steel plate and held at 50 ℃ for 30 minutes, and then the adhesive force N was measured at 23 ℃ ₅₀ And an adhesive force N measured at 23 ℃ after being bonded to a stainless steel plate and heated at 80 ℃ for 5 minutes ₈₀ Satisfies the following equation: (N) ₈₀ /N ₅₀ )≥3。

Description

Adhesive sheet

Technical Field

The present invention relates to an adhesive sheet. Priority is claimed in this application based on japanese patent application No. 2018-225412 filed on 2018, 11, 30, the entire contents of which are incorporated by reference into this specification.

Background

The pressure-sensitive adhesive sheet is used for purposes such as adhesion of adherends to each other, fixation of an article to an adherend, and reinforcement of an adherend by being strongly adhered to the adherend. Conventionally, for such a purpose, an adhesive sheet that exhibits high adhesive force from the initial stage of the attachment has been used. Further, recently, as disclosed in patent documents 1 to 3, pressure-sensitive adhesive sheets have been proposed which can exhibit a low adhesive force at the initial stage of attachment to an adherend and can increase the adhesive force greatly thereafter. The pressure-sensitive adhesive sheet having such properties can exhibit re-adhesiveness (reworkability) useful for suppressing a reduction in yield due to misapplication or adhesive failure of the pressure-sensitive adhesive sheet before the increase in adhesive strength, and exhibit strong adhesiveness suitable for the intended use of the pressure-sensitive adhesive sheet after the increase in adhesive strength.

Documents of the prior art

Patent document

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

However, depending on the mode of use of the pressure-sensitive adhesive sheet, after the application and after the progress to the subsequent steps, there is a case where a rework request is generated due to the occurrence of a positional deviation due to the influence of an attachment error, the confirmation of a damage of the application, the subsequent steps, and the like. In such a case, while reworkability is required for the pressure-sensitive adhesive sheet to be attached to an adherend, the pressure-sensitive adhesive sheet may be subjected to temperatures of about 40 to 50 ℃ due to incidental factors such as an influence of heat generation accompanying operations of apparatuses (a conveying apparatus, an inspection apparatus, other various processing apparatuses, and the like) used in the manufacturing process, heat release from an adjacent apparatus, and a temperature rise in the manufacturing environment. Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive sheet which can maintain reworkability even when a temperature of about 50 ℃ is applied in the initial stage of attachment to an adherend, and can increase adhesive strength significantly thereafter.

Means for solving the problems

According to the present specification, there is provided an adhesive sheet comprising an adhesive layer. The pressure-sensitive adhesive layer contains a polymer a as a polymer of a monomer raw material a and a polymer B as a polymer of a monomer raw material B. The monomer raw material B contains a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer. That is, the above-mentioned polymer B isA copolymer of the above-mentioned monomer having a polyorganosiloxane skeleton and the above-mentioned (meth) acrylic monomer. The weight average molecular weight (Mw) of the polymer B was 7X 10 ⁴ As described above. The adhesive sheet was adhered to a stainless steel plate and held at 50 ℃ for 30 minutes, and then the adhesive force N was measured at 23 ℃ ₅₀ And an adhesive force N measured at 23 ℃ after being bonded to a stainless steel plate and heated at 80 ℃ for 5 minutes ₈₀ Satisfies the following equation: (N) ₈₀ /N ₅₀ )≥3。

The adhesive sheet with the structure contains Mw of 7 x 10 ⁴ The above polymer B can improve the adhesive force N ₈₀ (hereinafter, also referred to as "adhesion after heating") with respect to the adhesion N ₅₀ The efficiency is improved by more than 3 times. This can exhibit good reworkability even in a use mode in which a temperature of about 50 ℃ may be applied at the initial stage of adhesion, and can significantly increase the adhesive strength by subsequent heating or the like.

Several modes of adhesive sheets, the adhesive force N ₅₀ And the adhesive force N measured at 23 ℃ after being attached to a stainless steel plate and left at 23 ℃ for 30 minutes ₂₃ Satisfies the following equation: (N) ₅₀ /N ₂₃ ) Is less than 10. Such a pressure-sensitive adhesive sheet is preferable from the viewpoint of workability and ease of process control because the difference in adhesive strength (and hence reworkability) between the case of being maintained at room temperature at the initial stage of attachment and the case of being exposed to temperatures up to about 50 ℃.

The adhesive sheet disclosed herein is preferably the above adhesive force N ₈₀ Adhesive force N measured at 80 ℃ after being bonded to a stainless steel plate and kept at 80 ℃ for 30 minutes _H Satisfies the following equation: (N) _H /N ₈₀ ) Not less than 15 percent. Such adhesive sheet and (N) _H /N ₈₀ ) Smaller adhesive sheets have superior heat resistance.

The (meth) acrylic monomer contained in the monomer raw material B preferably contains a monomer M2 having a homopolymer glass transition temperature (Tg) of 50 ℃ or higher. According to the polymer B formed from the monomer raw material B containing the monomer having a polyorganosiloxane skeleton and the (meth) acrylic monomer M2 having a Tg of 50 ℃ or more, the adhesive sheet satisfying one or more of the relational expressions described above can be easily obtained. As the monomer M2, an alkyl (meth) acrylate (i.e., alkyl (meth) acrylate) having a homopolymer Tg of 50 ℃ or higher can be preferably used.

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 or more and 50 parts by weight or less with respect to 100 parts by weight of the polymer a. With the content in the above range, a pressure-sensitive adhesive sheet having low adhesive strength in the initial stage of attachment and high adhesive strength after heating can be easily obtained.

The polymer a is preferably an acrylic polymer. According to the pressure-sensitive adhesive layer containing the polymer a as an acrylic polymer and the polymer B as a copolymer of a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer, a pressure-sensitive adhesive sheet having low adhesive force in the initial stage of attachment and high adhesive force after heating can be easily obtained.

In some embodiments, the monomer raw material a preferably contains a monomer having a nitrogen atom-containing ring. By reacting a polymer A (for example, an acrylic polymer) obtained from a monomer raw material A containing a monomer having a nitrogen atom-containing ring with a monomer having an Mw of 7X 10 ⁴ When the above polymers B are used in combination, a pressure-sensitive adhesive sheet having low adhesive strength in the initial stage of adhesion and high adhesive strength after heating can be easily obtained.

In some embodiments, the adhesive layer may contain more than 0 part by weight and 10 parts by weight or less of a crosslinking agent with respect to 100 parts by weight of the polymer a. By using the crosslinking agent, the adhesive strength at the initial stage of attachment can be effectively adjusted in a temperature range up to about 50 ℃. This makes it easy to obtain a pressure-sensitive adhesive sheet that suitably combines the reworkability at the initial stage of the adhesion and the strong adhesion after the increase in the adhesive strength.

The pressure-sensitive adhesive sheet disclosed herein may be implemented in the form of a substrate-attached pressure-sensitive adhesive sheet that includes 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. Such a pressure-sensitive adhesive sheet with a substrate can be a pressure-sensitive adhesive sheet having excellent handling properties and processability. As the support base, for example, a resin film having a thickness of 30 μm or more can be preferably used.

It should be noted that the invention as claimed in the present patent application also includes an embodiment in which the above-described elements are appropriately combined.

Drawings

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

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

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

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described. Matters necessary for carrying out the present invention other than those specifically mentioned in the present specification can be understood by those skilled in the art based on the teaching of the present invention and the technical common general knowledge at the time of application. The present invention can be implemented based on the contents disclosed in the present specification and the common general knowledge in the art.

In the following drawings, members and portions that exhibit the same function are sometimes denoted by the same reference numerals, and redundant description may be omitted or simplified. The embodiments shown in the drawings are schematic for clearly explaining the present invention, and do not necessarily accurately show the size and scale of a product to be actually provided.

In the present specification, the term "acrylic polymer" refers to a polymer having a polymer structure containing a monomer unit derived from a (meth) acrylic monomer, and typically refers to a polymer containing a monomer unit derived from a (meth) acrylic monomer in a proportion of more than 50% by weight. The (meth) acrylic monomer is a monomer having at least one (meth) acryloyl group in 1 molecule. Here, "(meth) acryloyl group" means a meaning including an acryloyl group and a methacryloyl group. Therefore, the concept of the (meth) acrylic monomer described here may include both a monomer having an acryloyl group (acrylic monomer) and a monomer having a methacryloyl group (methacrylic monomer). Similarly, in the present specification, "(meth) acrylic acid" means a meaning including acrylic acid and methacrylic acid, and "(meth) acrylate" means a meaning including acrylate and methacrylate.

< construction example of pressure-sensitive adhesive sheet >

The pressure-sensitive adhesive sheet disclosed herein is configured to include a pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet disclosed herein may be in the form of a substrate-attached pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is laminated on one or both surfaces of a support substrate, or may be in the form of a substrate-free pressure-sensitive adhesive sheet without a support substrate. Hereinafter, the supporting 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 base-attached one-sided pressure-sensitive adhesive sheet including a sheet-like support base 10 having a first surface 10A and a second surface 10B, and a pressure-sensitive 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 base 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 psa sheet 1 before use (i.e., before application to an adherend) may be a component of a release-lined psa sheet 100 in which a surface (adhesive surface) 21A of the psa layer 21 is in contact with a release liner 31, which is a releasable surface (release surface) at least on the side facing the psa layer 21. As the release liner 31, for example, a release liner configured such that a release layer formed by a release treatment agent is provided on one surface of a sheet-like base material (liner base material) and the one surface becomes a release surface can be preferably used. Alternatively, the release liner 31 may be omitted, and the psa sheet 1 may be wound around a support substrate 10 having the second surface 10B serving as the release surface, so that the psa surface 21A is in contact with the second surface 10B of the support substrate 10 (in a rolled state). When the pressure-sensitive 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 pressure-sensitive adhesive surface 21A, and the exposed pressure-sensitive adhesive surface 21A is pressure-bonded to the adherend.

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

The structure of an adhesive sheet of yet another embodiment is schematically shown in fig. 3. The adhesive sheet 3 is configured as a substrate-less double-sided adhesive sheet formed of an adhesive layer 21. The psa sheet 3 is used by attaching a first psa surface 21A, which is one surface (first surface) of the psa layer 21, and a second psa surface 21B, which is the other surface (second surface) of the psa layer 21, to different locations of an adherend. As shown in fig. 3, the psa sheet 3 before use may be a release-lined psa sheet 300 in which the first psa surface 21A and the second psa surface 21B are in contact with release liners 31 and 32, which are release surfaces on at least the side facing the psa layer 21. Alternatively, the following release-liner-attached pressure-sensitive adhesive sheet may be constituted: the release liner 32 is omitted, and the release liner 31 having both surfaces serving as release surfaces is used, and the release liner-attached pressure-sensitive adhesive sheet is overlapped with the pressure-sensitive adhesive sheet 3 and wound in a spiral shape, whereby the second pressure-sensitive adhesive surface 21B is in contact with the back surface of the release liner 31 (wound form).

The term "pressure-sensitive adhesive sheet" as used herein includes members referred to as pressure-sensitive adhesive tapes, pressure-sensitive adhesive films, pressure-sensitive adhesive labels, and the like. The pressure-sensitive adhesive sheet may be in a roll form, a sheet form, or a form cut, punched, etc. into an appropriate shape according to the application and the use. The adhesive layer in the technique 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 pattern or a stripe pattern.

< adhesive layer >

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

(Polymer A)

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

Glass transition temperature of Polymer ADegree T _A The pressure-sensitive adhesive sheet disclosed herein may be selected so as to obtain preferable properties, without particular limitation. Among several ways, T may be preferably employed _A Polymer A at less than 0 ℃. Since the adhesive containing such a polymer a exhibits appropriate fluidity (for example, mobility of a polymer chain contained in the adhesive), it is suitable for realizing an adhesive sheet having both initial low adhesiveness and strong adhesiveness after heating. The adhesive sheet disclosed herein may preferably use T _A Less than-10 deg.C, less than-20 deg.C, less than-30 deg.C or less than-35 deg.C. In several ways, T _A Can be less than-40 ℃ and can also be less than-50 ℃. T is _A The lower limit of (b) is not particularly limited. From the viewpoint of easy availability of the material and improvement in the cohesive force of the pressure-sensitive adhesive layer, it is generally preferable to use T _A Is a polymer A with the temperature of more than 80 ℃ below zero and more than 70 ℃ below zero or more than 65 ℃ below zero. From inhibition of N ₅₀ From the viewpoint of the rising of (1), in some aspects, T _A For example, it may be at least-63 ℃, at least-55 ℃, at least-50 ℃ or at least-45 ℃.

Herein, the glass transition temperature (Tg) of a polymer in the present specification means a nominal value described in documents, catalogs, and the like, or Tg obtained from the Fox equation based on the composition of a monomer raw material used for producing the polymer. The Fox formula is a relational expression between Tg of a copolymer and glass transition temperature Tgi of a homopolymer obtained by homopolymerizing 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 on a weight basis) of the monomer i in the copolymer, and Tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer i. In the case where the polymer of the subject whose Tg is to be determined is a homopolymer, the Tg of the homopolymer coincides with the Tg of the polymer of the subject.

The glass transition temperature of the homopolymer used for the calculation of Tg was determined as described in the publicly known data. Specifically, numerical values in "Polymer Handbook" (3 rd edition, John Wiley & Sons, Inc., 1989) can be cited. The highest value was used for the monomers having various values described in the above Polymer Handbook.

As the glass transition temperature of a homopolymer of a monomer not described in the above Polymer Handbook, a value obtained by the following measurement method was used.

Specifically, 100 parts by weight of a monomer, 0.2 parts by weight of 2,2' -azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent were put into a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, and stirred for 1 hour while flowing nitrogen. After removing oxygen from the polymerization system in this manner, the temperature was raised to 63 ℃ to allow the reaction to proceed for 10 hours. Subsequently, 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 sample was punched out into a disk shape having a diameter of 7.9mm, and the disk shape was held between parallel plates, and viscoelasticity was measured by a shear mode in a temperature range of-70 ℃ to 150 ℃ at a temperature rise rate of 5 ℃/min while applying a shear strain having a frequency of 1Hz using a viscoelasticity tester (TA Instruments, model name "ARES"), and the temperature corresponding to the peak top temperature of tan δ was defined as Tg of the homopolymer.

The weight average molecular weight (Mw) of the polymer A is usually suitably about 20X 10 ⁴ The above is not particularly limited. With this Mw of polymer a, an adhesive showing good cohesion is easily obtained. From the viewpoint of obtaining higher cohesive force, the Mw of the polymer a may be, for example, 30 × 10 in some embodiments ⁴ Above, it may be 40 × 10 ⁴ Above, it may be 50X 10 ⁴ Above, it may be 60 × 10 ⁴ Above, 80 × 10 may be used ⁴ The above. In addition, the Mw of the polymer A is usually suitably about 500X 10 ⁴ The following. Since the polymer a having Mw is likely to form an adhesive agent exhibiting appropriate fluidity (mobility of polymer chains), it is suitable for realizing an adhesive sheet having low adhesive strength at the initial stage of adhesion and high adhesive strength after heating. It is also preferable that the Mw of the polymer A is not too high from the viewpoint of improving compatibility with the polymer BIn (1). In several aspects, the Mw of polymer A can be, for example, 250X 10 ⁴ Hereinafter, it may be 200 × 10 ⁴ Hereinafter, the value may be 150 × 10 ⁴ The following.

In the present specification, the Mw of the polymer a and the polymer B can be determined by Gel Permeation Chromatography (GPC) in terms of polystyrene. More specifically, the Mw can be measured according to the method and conditions described in the 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 between the polymer a and the polymer B is good, the mobility of the polymer B in the pressure-sensitive adhesive layer is improved, which contributes to the reduction of the initial adhesive force and the improvement of the adhesive force after heating.

The acrylic polymer may be, for example, a polymer containing 50 wt% or more of a monomer unit derived from an alkyl (meth) acrylate, that is, a polymer in which 50 wt% or more of the total amount of monomer components (monomer raw material a) used for producing the acrylic polymer is an alkyl (meth) acrylate. As the alkyl (meth) acrylate, those having 1 to 20 carbon atoms (i.e., C) _1-20 Of (b) a linear or branched alkyl (meth) acrylate. (meth) acrylic acid C in monomer raw material A from the viewpoint of easy availability of balance of characteristics _1-20 The ratio of the alkyl ester may be, for example, 50 wt% or more, 60 wt% or more, or 70 wt% or more. For the same reason, (meth) acrylic acid C in 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 raw material 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 specific examples of the alkyl ester include (methyl group)) Methyl 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, dodecyl (meth) acrylate, hexyl (meth) acrylate, ethyl (meth) acrylate, ethyl acrylate, butyl acrylate, cetyl (meth) acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like.

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

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

Specific non-limiting examples of the copolymerizable monomer include the following monomers.

Hydroxyl group-containing monomer: examples of the (meth) acrylic acid include 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.

Monomer having nitrogen atom-containing ring: such as N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1, 3-oxazin-2-one, N-vinyl-3, 5-morpholinodione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridazine, etc.;

a monomer having a succinimide skeleton such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxohexamethylene succinimide, N- (meth) acryloyl-8-oxohexamethylene succinimide, etc.;

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

for example, itaconimides such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide and N-laurylitaconimide.

Carboxyl group-containing monomer: 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 monomer: examples of the epoxy group-containing acrylate include glycidyl (meth) acrylate, 2-ethyl glycidyl (meth) acrylate, allyl glycidyl ether, and glycidyl (meth) acrylate.

A cyano group-containing monomer: such as acrylonitrile, methacrylonitrile, and the like.

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

Amide group-containing monomer: 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, and N, N-di (tert-butyl) (meth) acrylamide; 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 such as N-hydroxyalkyl (meth) acrylamides including 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, and N- (4-hydroxybutyl) (meth) acrylamide; 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: for example, aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, N-diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate.

An alkoxy group-containing monomer: alkoxyalkyl (meth) acrylate esters such as 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, and ethoxypropyl (meth) acrylate; alkoxyalkylene glycol (meth) acrylates such as methoxyethylene glycol (meth) acrylate and methoxypolypropylene glycol (meth) acrylate.

Sulfonic acid group-or phosphoric acid group-containing monomer: for example, styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2- (meth) acrylamido-2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalenesulfonic acid, 2-hydroxyethylacryloyl phosphate, and the like.

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

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

Vinyl ethers: examples of the vinyl alkyl ether include 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, and the like.

And heterocyclic ring-containing (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. From the viewpoint of more satisfactorily exhibiting the effects of the use of the copolymerizable monomer, the amount of the copolymerizable monomer to be used may be 0.1% by weight or more, or may be 1% by weight or more, based on the monomer raw material a. The amount of the copolymerizable monomer used 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 adhesive feeling at normal temperature (25 ℃). In some embodiments, the amount of the copolymerizable monomer used may be 40% by weight or less, or 35% by weight or less, of the monomer raw material a.

In several ways, the monomer feed A may comprise a monomer having a ring containing a nitrogen atom. By using the monomer having a nitrogen atom-containing ring, the cohesive force and polarity of the adhesive can be adjusted, and the adhesive force after heating can be improved. The Mw of polymer B is as high as disclosed herein to some extent (typically 7X 10 ⁴ Above, preferably 8X 10 ⁴ Above, e.g. more than 10X 10 ⁴ ) Of the embodiments (3) above, it is particularly advantageous to include a monomer having a nitrogen atom-containing ring in the monomer raw material A. This tends to improve the compatibility between the polymer a formed from the monomer raw material a and the polymer B. This makes it easy to obtain a pressure-sensitive adhesive sheet which can maintain reworkability even when a temperature of about 50 ℃ is applied at the initial stage of adhesion to an adherend and can thereafter increase the adhesive strength significantly. The compatibility of the polymer B having a high Mw to some extent in the adhesive layer is also preferable from the viewpoint of improving the heat resistance of the adhesive sheet.

The monomer having a nitrogen atom-containing ring may be appropriately selected from the above-mentioned examples, and may be 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 raw material A may contain only one or two or more of the N-vinylcycloamides 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-vinylcycloamide 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-morpholinodione. N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactam are particularly preferable.

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

By using the hydroxyl group-containing monomer, the cohesive force and polarity of the adhesive can be adjusted, and the adhesive force after heating can be improved. The hydroxyl group-containing monomer provides a reaction site with a crosslinking agent (for example, an isocyanate-based crosslinking agent) described later, and the cohesive force of the adhesive can be increased 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. Among them, preferred examples include 2-hydroxyethyl acrylate (HEA), 4-hydroxybutyl acrylate (4HBA), and N- (2-hydroxyethyl) acrylamide (HEAA).

The amount of the hydroxyl group-containing monomer used is not particularly limited, and is usually preferably 0.01% by weight or more (preferably 0.1% by weight or more, for example, 0.5% by weight or more) of the monomer raw material A. In some embodiments, the amount of the hydroxyl group-containing monomer used may be 1% by weight or more, 5% by weight or more, or 10% by weight or more of the monomer raw material a. From the viewpoint of improving the tacky feeling at room temperature (25 ℃) and improving the flexibility at low temperature, the amount of the hydroxyl group-containing monomer used is usually preferably 40% by weight or less, and may be 30% by weight or less, and may be 20% by weight or less, and may be 10% by weight or less, or 5% by weight or less of the monomer raw material a.

In some embodiments, as the copolymerizable monomer, a monomer having a nitrogen atom-containing ring (for example, N-vinyl cyclic amide) may be used in combination with the 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 is, for example, 50 wt% or less, preferably 40 wt% or less of the monomer raw material a.

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

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

The method for obtaining the polymer a is not particularly limited, and various polymerization methods such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization can be suitably used. Among several ways, solution polymerization can be preferably employed. The polymerization temperature in the solution polymerization may be appropriately selected depending on the kind of the monomer and the solvent used, the kind of the polymerization initiator, and the like, and may be, for example, about 20 to 170 ℃ (typically about 40 to 140 ℃).

The initiator used 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 polymerization initiators (e.g., 2,2' -azobisisobutyronitrile, 2,2' -azobis-2-methylbutyronitrile, dimethyl 2,2' -azobis (2-methylpropionate), 4 ' -azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2' -azobis (2-amidinopropane) dihydrochloride, 2,2' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ] dihydrochloride, 2,2' -azobis (2-methylpropionamidine) disulfate, and 2,2' -azobis (N, N ' -dimethyleneisobutylamidine) dihydrochloride); persulfates such as potassium persulfate; peroxide-based polymerization initiators (e.g., dibenzoyl peroxide, t-butyl peroxymaleate, lauroyl peroxide, etc.); redox polymerization initiators, and the like. The amount of the thermal polymerization initiator to be 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 (monomer raw material a) used for the production of the acrylic polymer.

The photopolymerization initiator is not particularly limited, and for example, a benzoin ether type photopolymerization initiator, an acetophenone type photopolymerization initiator, an α -ketol type photopolymerization initiator, an aromatic sulfonyl chloride type photopolymerization initiator, a photoactive oxime type photopolymerization initiator, a benzoin type photopolymerization initiator, a benzil type photopolymerization initiator, a benzophenone type photopolymerization initiator, a ketal type photopolymerization initiator, a thioxanthone type photopolymerization initiator, an acylphosphine oxide type 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 the adhesive composition for forming the adhesive layer in the form of a partial polymer (polymer slurry) obtained by irradiating a mixture obtained by mixing the monomer raw material a with the polymerization initiator as described above with Ultraviolet (UV) light to polymerize a part of the monomer component. The adhesive composition containing the polymer slurry can be applied to a predetermined object to be coated, and ultraviolet rays can be irradiated to complete the polymerization. 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 polymer syrup and polymer B described above.

(Polymer B)

The polymer B in the technique disclosed herein is a copolymer of a monomer having a polyorganosiloxane skeleton (hereinafter, also referred to as "monomer S1") and a (meth) acrylic monomer. The polymer B can function as an adhesive force increase retarder that suppresses the adhesive force at the initial stage of attachment to an adherend and increases the adhesive force to the adherend by heating at a temperature higher than 50 ℃ or with the passage of time, due to the low polarity and mobility of the polyorganosiloxane structure derived from the monomer S1. The monomer S1 is not particularly limited, and any monomer having a polyorganosiloxane skeleton can be used. Since the monomer S1 has low polarity derived from its structure, the polymer B in the psa sheet before use (before attachment to an adherend) is promoted to be concentrated and distributed on the psa layer surface, and light peelability (low adhesiveness) at the initial stage of attachment is exhibited. As the monomer S1, a monomer having a structure having a polymerizable reactive group at one end can be preferably used. By copolymerization of the monomer S1 and the (meth) acrylic monomer, a polymer B having a polyorganosiloxane skeleton in the side chain is formed. The polymer B having the above structure is likely to have low initial adhesion and high adhesion after heating due to the mobility and ease of movement of the side chain. In some embodiments, it is preferable to use a monomer S1 having a polymerizable reactive group at one end and having no functional group that causes a crosslinking reaction with the polymer a at the other end. 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, X-22-174ASX, X-22-2426, X-22-2475, KF-2012, and the like, which are single-terminal reactive silicone oils available from shin-Etsu chemical Co., Ltd. The monomer 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 a 1-valent organic group, and m and n are integers of 0 or more.

The functional group equivalent of the monomer S1 is not limited to a specific range, and may be an appropriate value within a range in which the desired effect is exhibited by using the monomer S1. From the viewpoint of easily suppressing the initial adhesive force, the functional group equivalent may be, for example, 140g/mol or more, or 200g/mol or more, and is usually preferably 300g/mol or more (for example, 500g/mol or more), preferably 700g/mol or more, or 800g/mol or more, or 850g/mol or more, or 1000g/mol or more, or 1500g/mol or more. The technique disclosed herein can also be carried out in such a manner that the functional group equivalent is 2500g/mol or more, 3000g/mol or more, 4500g/mol or more, 6000g/mol or more, 9000g/mol or more, 12000g/mol or more, 15000g/mol or 16000g/mol or more. The functional group equivalent of the monomer S1 may be, for example, 50000g/mol or less, but from the viewpoint of improving the adhesive strength after heating, it is usually favorably 30000g/mol or less, and preferably 20000g/mol or less. From this viewpoint, the functional group equivalent may be, for example, less than 18000g/mol, less than 15000g/mol, less than 10000g/mol, less than 6000g/mol, or less than 5000 g/mol.

In some embodiments, the functional group equivalent of the monomer S1 is, for example, preferably 700g/mol or more and less than 15000g/mol, more preferably 800g/mol or more and less than 10000g/mol, still more preferably 850g/mol or more and less than 6000g/mol, and particularly preferably 1500g/mol or more and less than 5000 g/mol. When the functional group equivalent of the monomer S1 is within the above range, the compatibility (for example, compatibility with the polymer a) or the mobility in the pressure-sensitive adhesive layer can be easily adjusted to an appropriate range, and a pressure-sensitive adhesive sheet having both of the initial low adhesiveness and the strong adhesiveness after the increase in the adhesive force at a high level can be easily realized.

Here, "functional group equivalent" means the weight of the main skeleton (for example, polydimethylsiloxane) bonded to 1 functional group on average. The labeling unit g/mol was converted to 1mol of the functional group. The functional equivalent of the monomer S1 can be determined, for example, by Nuclear Magnetic Resonance (NMR) ¹ The spectral intensity of H-NMR (proton NMR) was calculated. Based on ¹ The functional group equivalent (g/mol) of the monomer S1 in the spectral intensity of H-NMR was calculated from ¹ A general structure analysis method for H-NMR spectroscopy is described in Japanese patent No. 5951153, if necessary.

Two or more monomers having different functional group equivalent weights are used as the monomer SIn the case of 1, an arithmetic average value can be used as the functional group equivalent of the monomer S1. That is, n kinds of monomers having different functional group equivalent weights (monomer S1) ₁ Monomer S1 ₂ … … monomer S1 _n ) The functional group equivalent of the monomer S1 (a) can be calculated by the following formula.

Functional group equivalent (g/mol) of monomer S1 ═ monomer S1 ₁ Functional group equivalent of (2) monomer S1 ₁ Amount of blending + monomer S1 ₂ Functional group equivalent of (2) monomer S1 ₂ Amount of compounding + … … + monomer S1 _n Functional group equivalent of (2) x monomer S1 _n (ii) compounding amount)/(monomer S1 ₁ Amount of blending + monomer S1 ₂ Amount of compounding + … … + monomer S1 _n Amount of (2)

The amount of the monomer S1 used is not limited to a specific range, and may be an appropriate value within a range in which the desired effect is exhibited by using the monomer S1. In some embodiments, the amount of the monomer S1 in the total amount of the monomer components (monomer raw material B) used for preparing the polymer B may be, for example, 5% by weight or more from the viewpoint of easily suppressing the initial adhesive force, and is preferably 10% by weight or more, 15% by weight or more, and may be 20% by weight or more from the viewpoint of more favorably exerting the effect as an adhesive force increase retarder. The content of the monomer S1 in the monomer raw material B may be, for example, 80 wt% or less from the viewpoint of polymerization reactivity and compatibility, and is usually preferably 60 wt% or less, 50 wt% or less, 40 wt% or less, or 30 wt% or less from the viewpoint of improving the adhesive strength after heating. The technique disclosed herein can be carried out in such a manner that the content of the monomer S1 in the monomer raw material B is, for example, 5 wt% or more and 50 wt% or less, preferably 10 wt% or more and 40 wt% or less, and more preferably 15 wt% or more and 30 wt% or less, from the viewpoint of facilitating both suppression of initial adhesion and improvement of adhesion by heating.

The monomer raw material B contains a (meth) acrylic monomer copolymerizable with the monomer S1 in addition to the monomer S1. By copolymerizing one or two or more (meth) acrylic monomers with the monomer S1, the mobility of the polymer B in the adhesive layer can be appropriately adjusted. Copolymerizing the monomer S1 with a (meth) acrylic monomer may also help to 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, one or two or more of the above-exemplified monomers as the alkyl (meth) acrylate that can be used when the polymer a is an acrylic polymer can be used as the constituent component of the monomer raw material B. In several ways, the monomer raw material B may contain (meth) acrylic acid C _4-12 Alkyl esters (preferably C (meth) acrylic acid) _4-10 Alkyl esters, e.g. C (meth) acrylate _6-10 Alkyl esters). In other several ways, the monomer raw material 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 ester). The monomer raw material B may contain, for example, one or two or more selected from MMA, BMA and 2EHMA as the (meth) acrylic monomer.

Other examples of the (meth) acrylic monomer include (meth) acrylates having an alicyclic hydrocarbon group. For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, 1-adamantyl (meth) acrylate, and the like can be used. In some embodiments, the monomer raw material B may contain at least one selected from dicyclopentyl methacrylate, isobornyl methacrylate, and cyclohexyl methacrylate as the (meth) acrylic monomer.

The content of the alkyl (meth) acrylate and the (meth) acrylate having an alicyclic hydrocarbon group in the monomer raw material B may be, for example, 10 wt% or more and 95 wt% or less, 20 wt% or more and 95 wt% or less, 30 wt% or more and 90 wt% or less, 40 wt% or more and 90 wt% or less, or 50 wt% or more and 85 wt% or less. The use of an alkyl (meth) acrylate is advantageous from the viewpoint of ease of increase in adhesive force by heating to a temperature higher than 50 ℃. In some embodiments, the content of the (meth) acrylate having an alicyclic hydrocarbon group may be less than 50% by weight, less than 30% by weight, less than 15% by weight, less than 10% by weight, or less than 5% by weight of the monomer raw material B. The (meth) acrylate having an alicyclic hydrocarbon group may not be used.

In some preferred embodiments, the (meth) acrylic monomer as a constituent of the monomer raw material B may include a monomer M2 having a homopolymer Tg of 50 ℃ or higher. To a certain extent or more (e.g. 7X 10) ⁴ Above, 8 × 10 ⁴ Above, further more than 10X 10 ⁴ ) The Mw polymer B of (1) has N inhibition by copolymerizing the monomer S1 with the monomer M2 ₅₀ /N ₂₃ The tendency of (c). This is considered to be because the repeating unit derived from the monomer M2 effectively suppresses the increase in mobility and mobility of the polyorganosiloxane moiety accompanying the temperature increase from room temperature to about 50 ℃, and the low adhesiveness due to the presence of the polyorganosiloxane moiety can be maintained more favorably. From increasing inhibition of N ₅₀ /N ₂₃ From the viewpoint of the effect of (b), in some embodiments, the Tg of the homopolymer of the monomer M2 may be 60 ℃ or higher, 70 ℃ or higher, 80 ℃ or higher, or 90 ℃ or higher. The upper limit of the Tg of the homopolymer of the monomer M2 is not particularly limited, but is preferably 200 ℃ or lower in view of ease of synthesis of the polymer B and the like. In some embodiments, the homopolymer of monomer M2 may have a Tg of, for example, 180 ℃ or lower, 150 ℃ or lower, or 120 ℃ or lower.

As the monomer M2, for example, a monomer whose homopolymer Tg satisfies the condition can be used from among the (meth) acrylic monomers exemplified above. For example, one or more monomers selected from the group consisting of alkyl (meth) acrylates and (meth) acrylates having an alicyclic hydrocarbon group 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 embodiment where the monomer raw material B contains the monomer M2, the content of the monomer M2 may be, for example, the monomer raw materialB may be 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. 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 N may be increased by increasing the content ₈₀ /N ₅₀ From the viewpoint of (1), it is usually preferably 80% by weight or less, preferably 75% by weight or less, and may be 70% by weight or less, may be 65% by weight or less, and may be 60% by weight or less. The content of the monomer M2 can be preferably applied to, for example, a mode in which the monomer M2 contains one or more monomers selected from the group consisting of an alkyl (meth) acrylate and the (meth) acrylate having an alicyclic hydrocarbon group, or a mode in which the monomer M2 contains one or more monomers selected from an alkyl (meth) acrylate (for example, an alkyl methacrylate). As a preferred example of this embodiment, there can be mentioned a preferred embodiment in which the monomer M2 contains MMA.

In some embodiments, the (meth) acrylic monomer may also include M3, a homopolymer of which has a Tg of less than 50 deg.C (typically greater than-20 deg.C and less than 50 deg.C). By using the monomer M3, a pressure-sensitive adhesive sheet having both adhesive force and cohesive force in a balanced manner after the adhesive force is increased can be easily obtained. From the viewpoint of easily exerting this effect, the monomer M3 is preferably used in combination with the monomer M2.

As the monomer M3, for example, a monomer whose homopolymer Tg satisfies the condition can 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 raw material B contains the monomer M3, the content of the monomer M3 may be, for example, 5% by weight or more, 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, or 35% by weight or more of the monomer raw material B. The content of the monomer M3 is usually preferably 70% by weight or less, and may be 60% by weight or less, or 50% by weight or less of the monomer raw material B. The content of the monomer M3 described above can be preferably applied to, for example, a mode in which the monomer M3 contains one or more monomers selected from alkyl (meth) acrylates (e.g., alkyl methacrylates).

In some embodiments of the adhesive sheet disclosed herein, the monomer raw material B preferably contains 30% by weight or less of a monomer having a homopolymer Tg higher than 170 ℃. In the present specification, the content of the monomer is X wt% or less, and unless otherwise specified, the content is a concept including a mode in which the content of the monomer is 0 wt%, that is, a mode in which the monomer is not substantially included. The term "substantially not included" means that at least the monomer is not used intentionally. When the copolymerization ratio of the monomer having a homopolymer Tg of more than 170 ℃ is high, the mobility of the polymer B tends to be insufficient, and the increase in the adhesive force caused by heating to a temperature range of more than 50 ℃ may be difficult. N can be achieved by setting the copolymerization ratio of the monomer having a homopolymer Tg of more than 170 ℃ to less than 30% by weight ₈₀ Is increased and N ₅₀ /N ₈₀ At least one effect of improvement of (1).

In some aspects, the monomer raw material B preferably contains at least MMA as the (meth) acrylic monomer. By copolymerizing MMA to obtain the polymer B, N can be easily obtained ₈₀ /N ₅₀ Large adhesive sheets. The ratio of MMA contained in the monomer raw material B in the total amount of the (meth) acrylic monomers may be, for example, 5 wt% or more, 10 wt% or more, 20 wt% or more, 30 wt% or more, or 40 wt% or more. In some embodiments, the proportion 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. In addition, the ratio of MMA in the total amount of the above (meth) acrylic monomers is usually preferably 95 wt% or less, may be 90 wt% or less, and may be 85 wt% or less.

For other examples of monomers that may be contained as monomer units constituting polymer B together with monomer S1, examples of the monomer that can be used when the polymer a is an acrylic polymer include a carboxyl group-containing monomer, an acid anhydride group-containing monomer, a hydroxyl group-containing monomer, an epoxy group-containing monomer, a cyano group-containing monomer, an isocyanate group-containing monomer, an amide group-containing monomer, a monomer having a nitrogen atom-containing ring (N-vinyl cyclic amide, a monomer having a succinimide skeleton, maleimides, itaconimides, etc.), (meth) acrylic acid aminoalkyl esters, vinyl ethers, olefins, (meth) acrylic acid esters having an aromatic hydrocarbon group, heterocyclic ring-containing (meth) acrylic acid esters, (meth) acrylic acid esters containing a halogen atom, and (meth) acrylic acid esters obtained from terpene compound derivative alcohols.

Further examples of monomers which may be contained as monomer units constituting the polymer B together with the monomer S1 include: 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; a monomer having a polyoxyalkylene skeleton, for example, a polymerizable polyoxyalkylene ether having a polymerizable functional group such as a (meth) acryloyl group, vinyl group, or allyl group at one end of a polyoxyalkylene chain such as polyethylene glycol or polypropylene glycol, and having an ether structure (alkyl ether, aryl ether, arylalkyl ether, or the like) at the other end; alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, and ethoxypropyl (meth) acrylate; salts such as alkali metal (meth) acrylate; polyhydric (meth) acrylates such as trimethylolpropane tri (meth) acrylate: halogenated vinyl compounds such as vinylidene chloride and 2-chloroethyl (meth) acrylate; oxazoline group-containing monomers such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline and the like; aziridinyl group-containing monomers such as (meth) acryloyl aziridine and 2-aziridinylethyl (meth) acrylate; hydroxyl group-containing vinyl monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and adducts of lactones and 2-hydroxyethyl (meth) acrylate; fluorine-containing vinyl monomers such as fluorine-substituted alkyl (meth) acrylates; reactive halogen-containing vinyl monomers such as 2-chloroethyl vinyl ether and monochloroacetic acid vinyl ester; silicone-containing vinyl monomers such as vinyltrimethoxysilane, gamma- (meth) acryloyloxypropyltrimethoxysilane, allyltrimethoxysilane, trimethoxysilylpropylallylamine, and 2-methoxyethoxy-trimethoxysilane; and macromonomers having a radical polymerizable vinyl group at the terminal of a monomer obtained by polymerizing a vinyl group; and the like. They may be copolymerized with the monomer S1 by using one kind alone or two or more kinds in combination.

Among several ways, as the polymer B, a polymer having no functional group which causes a crosslinking reaction with the polymer a may be preferably used. In other words, the polymer B is preferably contained in the adhesive layer in a form that is not chemically bonded to the polymer a. The pressure-sensitive adhesive layer containing the polymer B in such a form is suitable for improving the adhesive strength increase ratio because the mobility of the polymer B is good when heated. The functional group which causes a crosslinking reaction with the polymer a may be different depending on the kind of the functional group of the polymer a, and may be, for example, an epoxy group, an isocyanate group, a carboxyl group, an alkoxysilyl group, an amino group, or the like.

The adhesive sheet disclosed herein has Mw of 7X 10 ⁴ The above polymer B. Using a polymer B containing Mw as described above to a certain extent or more and satisfying (N) ₈₀ /N ₅₀ ) The pressure-sensitive adhesive sheet having a constitution of not less than 3 exhibits good reworkability even in a use form in which a temperature of about 50 ℃ may be applied at the initial stage of the sticking, and the adhesive strength can be greatly improved by subsequent heating or the like. In several aspects, the Mw of the polymer B may be, for example, 7.5X 10 ⁴ Above, higher N is easily achieved ₈₀ /N ₅₀ From the viewpoint of (2), the value may be 8X 10 ⁴ The above. In several ways, the Mw of polymer B is increased from heat resistance (e.g., by N) _H Improvement of (2)、N _H /N ₈₀ Increase in size, etc.) of the base material, for example, 10 × 10 may be used ⁴ Above, it may exceed 10X 10 ⁴ And may be 12X 10 ⁴ Above, it may be 15 × 10 ⁴ The above. It is also advantageous to increase the Mw of the polymer B from the viewpoint of increasing the cohesive property of the adhesive to suppress cohesive failure at the time of reprocessing.

The Mw of the polymer B may be, for example, less than 50X 10 ⁴ From the viewpoint of suppressing initial adhesion and improving reworking workability, it is advantageously less than 40 × 10 ⁴ May be less than 35 × 10 ⁴ Or less than 30X 10 ⁴ . When the Mw of the polymer B is within the above-mentioned arbitrary upper limit and lower limit, it is easy to adjust the compatibility and mobility in the pressure-sensitive adhesive layer to appropriate ranges, and it is easy to realize a pressure-sensitive adhesive sheet which has both good reworkability at the initial stage of adhesion and strong adhesiveness after an increase in adhesive strength at a high level.

In several preferred modes, the Mw of polymer B is preferably lower than the Mw of polymer a. This makes it easy to realize a pressure-sensitive adhesive sheet which has both good reworkability at the initial stage of adhesion and strong adhesion after an increase in adhesive strength at a high level. 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, or 0.3 times or less the Mw of the polymer a. The Mw of the polymer B is suitably, for example, 10X 10 lower than the Mw of the polymer A ⁴ Above, preferably 20X 10 below ⁴ Above, more preferably 30X 10 below ⁴ As described above.

The polymer B can be produced by polymerizing the above-mentioned monomers by a known method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, or photopolymerization.

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

The amount of the chain transfer agent to be used is not particularly limited, and is usually 0.05 to 20 parts by weight, preferably 0.1 to 15 parts by weight, and more preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the monomer. By adjusting the amount of the chain transfer agent added 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 a means for adjusting the molecular weight of the polymer B, various conventionally known means including the use of the above-mentioned chain transfer agent can 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 a kind or an amount of a polymerization initiator, selection of a polymerization temperature, selection of a kind or an amount of a polymerization solvent in a solution polymerization method, selection of light irradiation intensity in a photopolymerization method, and the like. One skilled in the art can understand how to obtain a polymer having a desired molecular weight based on the description of the present specification including the specific examples described below and the technical common knowledge at the time of the present application.

In the psa sheet disclosed herein, the amount of the polymer B used may be, for example, 0.1 part by weight or more relative to 100 parts by weight of the polymer a, and from the viewpoint of obtaining higher effects, may be 0.5 part by weight or more, 1 part by weight or more, or 2 parts by weight or more. In some embodiments, the amount of the polymer B used may be, for example, 3 parts by weight or more, 4 parts by weight or more, or 5 parts by weight or more, from the viewpoint of improvement in reworkability or the like. The amount of the polymer B to be used may be, for example, 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 polymer a to be used. In some embodiments, the amount of the polymer B used 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, based on 100 parts by weight of the polymer a, from the viewpoint of avoiding an excessive decrease in the cohesive force of the pressure-sensitive adhesive layer. From the viewpoint of obtaining a higher adhesive strength after heating, the amount of the polymer B used may be 20 parts by weight or less, 17 parts by weight or less, 15 parts by weight or less, 12 parts by weight or less, or 10 parts by weight or less in some embodiments.

The pressure-sensitive adhesive layer may contain a polymer (an arbitrary polymer) other than the polymer a and the polymer B as necessary within a range not significantly impairing the performance of the pressure-sensitive adhesive sheet disclosed herein. The amount of such an arbitrary polymer to be used is usually suitably 20% by weight or less, and may be 15% by weight or less, and may be 10% by weight or less, of the entire polymer components contained in the pressure-sensitive adhesive layer. In some embodiments, the amount of the optional polymer may be 5% by weight or less, 3% by weight or less, or 1% by weight or less of the total amount of the polymer components. The pressure-sensitive adhesive layer may contain substantially no polymer other than the polymer a and the polymer B.

(crosslinking agent)

A crosslinking agent may be used as needed in the adhesive layer for the purpose of adjustment of cohesive force and the like. As the crosslinking agent, a crosslinking agent known in the field of adhesives can be used, and examples thereof include an epoxy crosslinking agent, an isocyanate crosslinking agent, a silicone crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, a silane crosslinking agent, an alkyl ether melamine crosslinking agent, and a metal chelate crosslinking agent. The crosslinking agent may be used singly or in combination of two or more. Examples of crosslinking agents which can be preferably used include: an epoxy crosslinking agent, an isocyanate crosslinking agent, a silane crosslinking agent, an alkyl etherified melamine crosslinking agent, and a metal chelate crosslinking agent. Examples of particularly preferable crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-based crosslinking agents.

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 isocyanates, and adducts thereof with polyols such as trimethylolpropane. Alternatively, a compound having at least 1 or more isocyanate groups and 1 or more unsaturated bonds in 1 molecule, specifically 2-isocyanatoethyl (meth) acrylate and the like can also be used as the isocyanate-based crosslinking agent. These may be used alone 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, diglycidylaniline, diamine glycidyl amine, N' -tetraglycidyl m-xylylenediamine, and 1, 3-bis (N, N-diglycidylaminomethyl) cyclohexane. These may be used singly or in combination of two or more.

The metal chelate compound which can be used as a crosslinking agent of a metal chelate system includes, as a metal component, aluminum, iron, tin, titanium, nickel and the like, and as a chelate component, acetylene, methyl acetoacetate, ethyl lactate and the like. These may be used alone or in combination of two or more.

The amount of the crosslinking agent used is not particularly limited, and may be set to an amount exceeding 0 part 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 part by weight or more, preferably 0.05 part by weight or more, based on 100 parts by weight of the polymer a. By increasing the amount of the crosslinking agent, the adhesive strength at the initial stage of attachment tends to be suppressed, and the reworkability tends to be improved. In some embodiments, the amount of the crosslinking agent used may be 0.1 part by weight or more, 0.5 part by weight or more, or 1 part by weight or more, based on 100 parts by weight of the polymer a. On the other handFrom the viewpoint of avoiding a decrease in adhesion due to an excessive increase in cohesive force, the amount of the crosslinking agent to be used is preferably 15 parts by weight or less, more preferably 10 parts by weight or less, and still more preferably 5 parts by weight or less, based on 100 parts by weight of the polymer a. Easily realize N ₈₀ /N ₅₀ From the viewpoint of high adhesive sheet, it is also advantageous not to use too much crosslinking agent.

The technique disclosed herein can be preferably carried out using at least an isocyanate-based crosslinking agent as the crosslinking agent. In some embodiments, the amount of the isocyanate-based crosslinking agent used may be, for example, 0.1 to 5 parts by weight, 0.3 to 4 parts by weight, or 0.5 to 3 parts by weight, based on 100 parts by weight of the polymer a, from the viewpoint of easily achieving a pressure-sensitive adhesive sheet having both good reworkability at the initial stage of adhesion and strong adhesiveness after an increase in adhesive strength.

When the isocyanate-based crosslinking agent is used in the structure in which the pressure-sensitive 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 Amount W used relative to isocyanate-based crosslinking agent _NCO May be set to W on a weight basis _OH /W _NCO In an amount of 2 or more. By increasing the amount of the hydroxyl group-containing monomer to the isocyanate-based crosslinking agent in this manner, a crosslinked structure suitable for greatly increasing the adhesive strength after heating relative to the adhesive strength at the initial stage of attachment can be formed. In several ways, W _OH /W _NCO 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 _OH /W _NCO The upper limit of (b) is not particularly limited. W _OH /W _NCO For example, 500 or less, 200 or less, or 100 or less may be used.

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

A polyfunctional monomer may be used in the adhesive layer as needed. The polyfunctional monomer can be used in place of or in combination with the crosslinking agent as described above, and can contribute to the purpose of adjusting the cohesive force. For example, a polyfunctional monomer can be preferably used for the pressure-sensitive adhesive layer formed of a photocurable pressure-sensitive adhesive composition.

Examples of the polyfunctional monomer include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 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-dodecyldiol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, epoxy acrylate, acrylic acid, butyl diol (meth) acrylate, hexyl diol di (meth) acrylate, and the like. Of these, trimethylolpropane tri (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, dipentaerythritol hexa (meth) acrylate can be suitably used. The polyfunctional monomer may be used alone or in combination of two or more.

The amount of the polyfunctional monomer used varies depending on the molecular weight, the number of functional groups, and the like, and is usually suitably in the range of about 0.01 to 3.0 parts by weight based on 100 parts by weight of the polymer a. In some embodiments, the amount of the polyfunctional monomer used may be, for example, 0.02 parts by weight or more, or 0.03 parts by weight or more, based on 100 parts by weight of the polymer a. By increasing the amount of the polyfunctional monomer used, the adhesive strength at the initial stage of attachment tends to be suppressed, and the reworkability tends to be improved. On the other hand, from the viewpoint of avoiding a decrease in adhesion due to an excessive increase in cohesive force, the amount of the polyfunctional monomer used is 100 parts by weight of the polymer aMay be 2.0 parts by weight or less, may be 1.0 parts by weight or less, or may be 0.5 parts by weight or less. Easily realize N ₈₀ /N ₅₀ From the viewpoint of high pressure-sensitive adhesive sheets, it is also advantageous not to use an excessive amount of the polyfunctional monomer.

(tackifying resin)

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

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

Examples of the rosin derivative include:

rosin phenol resins obtained by adding phenol to rosins (unmodified rosin, modified rosin, various rosin derivatives, and the like) with an acid catalyst and carrying out thermal polymerization;

ester compounds of rosin (unmodified rosin esters) obtained by esterifying unmodified rosin with alcohols; rosin ester-based resins such as ester compounds of modified rosins (polymerized rosin esters, stabilized rosin esters, disproportionated rosin esters, fully hydrogenated rosin esters, partially hydrogenated rosin esters, and the like) obtained by esterifying modified rosins such as polymerized rosin, stabilized rosin, disproportionated rosin, fully hydrogenated rosin esters, and partially hydrogenated rosin esters with alcohols;

unsaturated fatty acid-modified rosin resins obtained by modifying unmodified rosins and modified rosins (polymerized rosins, stabilized rosins, disproportionated rosins, fully hydrogenated rosins, partially hydrogenated rosins, and the like) with unsaturated fatty acids;

unsaturated fatty acid-modified rosin ester resins obtained by modifying rosin ester resins with unsaturated fatty acids;

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, and the like), 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 tackifier resin include terpene-based resins such as α -pinene polymer, β -pinene polymer, and dipentene polymer, and modified terpene-based resins (e.g., terpene-phenol-based resins, styrene-modified terpene-based resins, aromatic-modified terpene-based resins, and hydrogenated terpene-based resins) obtained by modifying (e.g., phenol modification, aromatic modification, hydrogenation modification, and hydrocarbon modification) these terpene-based resins.

Examples of the phenolic tackifier resin include condensates (for example, alkylphenol resin, xylene formaldehyde resin, and the like) of various phenols (for example, phenol, m-cresol, 3, 5-xylenol, p-alkylphenol, resorcinol, and the like) and formaldehyde, resol resins obtained by addition reaction of the above phenols and formaldehyde with an alkali catalyst, and novolacs obtained by condensation reaction of the above phenols and formaldehyde with an acid catalyst.

Examples of the hydrocarbon-based tackifier 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, and coumarone-indene-based resins.

Examples of commercially available polymerized rosin esters that can be preferably used include, but are not limited to, trade names "Pensel D-125", "Pensel D-135", "Pensel D-160", "Pensel KK" and "Pensel C" available from Seisawa chemical industries, Ltd.

Examples of commercially available terpene-phenol resins that can be preferably used include, but are not limited to, YASUHARA CHEMICAL CO., LTD.trade name "YS POLYSTER S-145", "YS POLYSTER G-125", "YS POLYSTER N125", "YS POLYSTER U-115", and Dachuan CHEMICAL Co., Ltd.trade name "Tamanol 803L", "Tamanol 901", Sumitomo Bakelite Co., Ltd.trade name "SUMILITERESIN PR-12603", and the like.

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

As the tackifier resin, a tackifier 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. By using a tackifier resin having a softening point of not less than the lower limit, N can be easily obtained ₈₀ /N ₅₀ An adhesive sheet of 5 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 tackifier resin can be measured according to a softening point test method (ring and ball method) specified in JIS K2207.

The pressure-sensitive adhesive layer in the technology disclosed herein may contain, as necessary, known additives that can be used in a pressure-sensitive adhesive such as a leveling agent, a plasticizer, a softening agent, a colorant (dye, pigment, or the like), a filler, an antistatic agent, an anti-aging agent, an ultraviolet absorber, an antioxidant, a light stabilizer, and an antiseptic agent, within a range that does not significantly impair 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 an aqueous dispersion type, a solvent type, a photocurable type, or a hot melt type to an appropriate surface and then appropriately performing a curing treatment. When two or more curing treatments (drying, crosslinking, polymerization, cooling, etc.) are performed, these may be performed simultaneously or in multiple stages. In the adhesive composition using a partial polymer (polymer slurry) of a monomer raw material, a final copolymerization reaction is typically performed as the 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, curing treatment such as crosslinking and drying may be performed. For example, when the composition is a photocurable adhesive composition and drying is required, it is preferable to perform photocuring after drying. The adhesive composition using a complete polymer is typically subjected to a treatment such as drying (heat drying) or crosslinking as necessary as the curing treatment.

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

The thickness of the pressure-sensitive adhesive layer is not particularly limited, and may be, for example, 1 μm or more. In some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 3 μm or more, 5 μm or more, 8 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, or more than 20 μm. By increasing the thickness of the pressure-sensitive adhesive layer, the adhesive strength tends to increase after heating. In some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, or 40 μm or less. From the viewpoint of thinning of the pressure-sensitive adhesive sheet, prevention of cohesive failure of the pressure-sensitive adhesive layer, and the like, it is advantageous that the thickness of the pressure-sensitive adhesive layer is not excessively large. In the case of a psa sheet having a first psa layer and a second psa layer on the first and second surfaces of a substrate, the thickness of the psa layer may be at least as great as the thickness of the first psa layer. The thickness of the second adhesive layer may also be selected from the same range. In the case of a pressure-sensitive adhesive sheet without a substrate, the thickness of the pressure-sensitive adhesive sheet corresponds to the thickness of the pressure-sensitive adhesive layer.

The gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is preferably in the range of usually 20.0% to 99.0%, and preferably 30.0% to 90.0%, although not particularly limited. By setting the gel fraction to the above range, it becomes easy to realize a pressure-sensitive adhesive sheet that achieves both a high level of reworkability at the initial stage of attachment and a high level of adhesiveness after an increase in adhesive strength. The gel fraction was measured by the following method.

[ measurement of gel fraction ]

With a porous polytetrafluoroethylene membrane having an average pore diameter of 0.2 μm (weight Wg) ₂ ) About 0.1g of an adhesive sample (weight Wg) ₁ ) Wrapped in a purse-shape with kite string (weight Wg) ₃ ) The mouth is pricked. As the above porous polytetrafluoroethylene film, a product name "NITOFLON (registered trademark) NTF 1122" (available from Nindon electric Co., Ltd., average pore diameter of 0.2 μm, porosity of 75%, thickness of 85 μm) or a product equivalent thereof was used. The pouch was immersed in 50mL of ethyl acetate and kept at room temperature (typically 23 ℃) for 7 days to elute the sol component (ethyl acetate-soluble component) in the binder out of the film. Subsequently, the pouch was taken out and the ethyl acetate adhered to the outer surface was wiped off, and then the pouch was dried at 130 ℃ for 2 hours to measure the weight (Wg) of the pouch ₄ ). The gel fraction G of the adhesive can be calculated by substituting the values into the following equation _C 。

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

< supporting base Material >

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

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

Examples of the resin material constituting the resin film include polyester, polyolefin, Polyamide (PA) such as nylon 6, nylon 66, and partially aromatic polyamide, Polyimide (PI), polyamide-imide (PAI), polyether ether ketone (PEEK), polyether sulfone (PES), polyphenylene sulfide (PPS), Polycarbonate (PC), Polyurethane (PU), ethylene-vinyl acetate copolymer (EVA), fluorine resins such as Polytetrafluoroethylene (PTFE), acrylic resins, polyacrylates, polystyrene, polyvinyl chloride, and polyvinylidene chloride. The resin film may be formed using a resin material containing one kind of such resin alone, or may be formed using a resin material in which two or more kinds of resins are mixed. The resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).

Suitable examples of the resin material constituting the resin film include polyester resins, PPS resins, and polyolefin resins. The polyester resin is a resin containing a polyester in a proportion of more than 50% by weight. Similarly, the PPS resin refers to a resin containing PPS in a proportion of more than 50 wt%, and the polyolefin resin refers to a resin containing polyolefin in a proportion of more than 50 wt%.

As the polyester resin, a polyester resin containing, as a main component, a polyester obtained by polycondensing a dicarboxylic acid and a diol 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-methylterephthalic acid, 5-sulfoisophthalic acid, 4 ' -diphenyldicarboxylic acid, 4 ' -diphenyletherdicarboxylic acid, 4 ' -diphenylketodicarboxylic acid, 4 ' -diphenoxyethanedicarboxylic acid, 4 ' -diphenylsulfonedicarboxylic acid, 1, 4-naphthalenedicarboxylic acid, 1, 5-naphthalenedicarboxylic acid, 2, 6-naphthalenedicarboxylic acid, and 2, 7-naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1, 2-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, and 1, 4-cyclohexanedicarboxylic acid; 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, and fumaric acid; derivatives thereof (e.g., lower alkyl esters of the above dicarboxylic acids such as terephthalic acid); and the like. These may be used singly or in combination of two or more. From the viewpoint of strength, etc., an aromatic dicarboxylic acid is preferred. Among them, preferable dicarboxylic acids include terephthalic acid and 2, 6-naphthalenedicarboxylic acid. For example, 50% by weight or more (for example, 80% by weight or more, typically 95% by weight or more) of the dicarboxylic acids constituting the polyester is preferably terephthalic acid, 2, 6-naphthalenedicarboxylic acid, or a combination thereof. The dicarboxylic acid may be substantially composed of only terephthalic acid, substantially composed of only 2, 6-naphthalenedicarboxylic acid, or substantially composed of only terephthalic acid and 2, 6-naphthalenedicarboxylic acid.

Examples of the diol 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 benzenedimethanol, 4 '-dihydroxybiphenyl, 2-bis (4' -hydroxyphenyl) propane and bis (4-hydroxyphenyl) sulfone; and the like. These may be used singly or in combination of two or more. Among them, from the viewpoint of transparency and the like, aliphatic diols are preferable, and ethylene glycol is particularly preferable. 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, typically 95% by weight or more). The 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 kind of polyolefin may be used alone, or two or more kinds of 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 two or more α -olefins with another vinyl monomer, 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 a non-stretched polypropylene (CPP) film, a biaxially stretched 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 in which two or more kinds of Polyethylenes (PE) are mixed, and a PP/PE mixed film in which polypropylene (PP) and Polyethylene (PE) are mixed.

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

The resin film may contain, as necessary, known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, lubricants, and antiblocking agents, within a range not significantly impairing the effects of the present invention. The amount of the additive to be blended is not particularly limited, and may be appropriately set according to the use of the pressure-sensitive adhesive sheet and the like.

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

The substrate may be a substrate substantially composed 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 optical property adjusting layers (for example, a colored layer and an antireflection layer), printing layers for giving a desired appearance to a substrate, lamination layers, antistatic layers, undercoating layers, release layers, and other surface treatment layers.

The thickness of the substrate 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 substrate may be, for example, 1000 μm or less. 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 handling properties and processability of the pressure-sensitive adhesive sheet. From the viewpoint of downsizing and weight reduction of a product to which the pressure-sensitive adhesive sheet is applied, the thickness of the substrate may be, for example, 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, in some embodiments. When the thickness of the substrate 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, and the like, the thickness of the base material may be, for example, 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 25 μm or more, or 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, in a pressure-sensitive adhesive sheet that can be used for the purposes of reinforcing, supporting, and impact-relaxing an adherend, a substrate having a thickness of 30 μm or more is preferably used.

The first surface of the substrate may be subjected to conventionally known surface treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, formation of an undercoat layer by coating with an undercoat agent (primer), or the like, 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 substrate including a resin film as a base film, a substrate subjected to the anchorage property improving treatment can be preferably used. The above surface treatments may be applied alone or in combination. The composition of the primer used for forming the undercoat layer is not particularly limited, and may be selected from known primers. The thickness of the undercoat layer is not particularly limited, and is usually preferably about 0.01 to 1 μm, more preferably about 0.1 to 1 μm. As other treatments that can be applied to the first surface of the base material as needed, antistatic layer formation treatment, coloring layer formation treatment, printing treatment, and the like can be cited.

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 only on the first side of a substrate, the second side of the substrate may be subjected to conventionally known surface treatment such as peeling treatment or antistatic treatment as needed. For example, the unwinding force of the psa sheet wound in a roll form can be reduced by surface-treating the back surface of the substrate with a release treatment agent (typically by providing a release layer based on the release treatment agent). Examples of the release treatment agent include 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, and silica powder. For the purpose of improving printability, reducing light reflectivity, improving reposability, and the like, the second surface of the base material may be subjected to a treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and the like. In the case of a double-sided adhesive sheet, the second surface of the substrate may be subjected to surface treatment as necessary, similar to the surface treatment exemplified above as the surface treatment that can be applied to the first surface of the substrate. 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 >

(characteristics of adhesive sheet, etc.)

The adhesive sheet disclosed herein has an adhesive force N ₈₀ [N/25mm]With respect to the adhesive force N ₅₀ [N/25mm]Ratio of (1), i.e., adhesive force increase ratio N ₈₀ /N ₅₀ Since the adhesive is 3 or more, excellent reworkability can be exhibited even in a use mode in which a temperature of about 50 ℃ may be applied at the initial stage of adhesion, and the adhesive strength can be greatly improved by subsequent heating or the like. From the viewpoint of obtaining a higher effect, N is, in some aspects ₈₀ /N ₅₀ For example, it may be 3.5 or more, 4.5 or more, 5.0 or more, 5.5 or more, or 6.0 or more. N is a radical of ₈₀ /N ₅₀ The upper limit of (2) is not particularly limited, and from the viewpoint of the easiness of production of the pressure-sensitive adhesive sheet and the economical efficiency, there are several modes, for exampleMay be 50 or less, may be 30 or less, may be 20 or less, or may be 10 or less. The adhesive sheet disclosed herein may be N ₈₀ /N ₅₀ For example, a mode of 3.0 to 50 inclusive, a mode of 3.5 to 50 inclusive, a mode of 5.0 to 30 inclusive, and the like are preferably performed.

In several ways, the adhesive force N ₅₀ [N/25mm]With respect to the adhesive force N ₂₃ [N/25mm]Ratio of (1), i.e., adhesive force increase ratio N ₅₀ /N ₂₃ Preferably less than 10, more preferably less than 7.0, and may be 6.0 or less, and may be 5.5 or less, and may be 5.0 or less, and may be less than 5.0. By using N ₅₀ /N ₂₃ A relatively small adhesive sheet tends to exhibit good reworkability even in a use mode in which a temperature of about 50 ℃ may be applied at the initial stage of adhesion. N is a radical of ₅₀ /N ₂₃ The lower limit of (b) is not particularly limited, but is usually 1.0 or more, typically more than 1.0, and may be 1.2 or more. From the easy compromise of a higher N ₈₀ /N ₅₀ From the viewpoint of (1), in some aspects, N ₅₀ /N ₂₃ For example, it may be 1.5 or more, 2.0 or more, or 2.5 or more.

In several ways, the adhesive force N ₈₀ [N/25mm]With respect to the adhesive force N ₂₃ [N/25mm]Ratio of (1), i.e., adhesive force increase ratio N ₈₀ /N ₂₃ For example, the number of the holes may be 5 or more, 7 or more, or 10 or more. By using N ₈₀ /N ₂₃ A large adhesive sheet can exhibit a high level of low adhesiveness at the initial stage of adhesion and strong adhesiveness after an increase in adhesive force. The adhesive sheet disclosed herein may also be represented by N ₈₀ /N ₂₃ For example, 15 or more, 20 or more, or 25 or more is preferably used. N is a radical of hydrogen ₈₀ /N ₂₃ The upper limit of (b) is not particularly limited, and may be, for example, 100 or less, 80 or less, 60 or less, or 50 or less, from the viewpoint of ease of production of the pressure-sensitive adhesive sheet and economy.

Here, adhesive force N ₂₃ [N/25mm]The following is held: pressure-bonded to a stainless steel (SUS) plate as an adherend and left to stand in an environment of 23 ℃ and 50% RH for 30 minutes, and then left to stand in that environment (i.e., at 23 ℃)) The 180 DEG peel adhesion was measured under the conditions of a peel angle of 180 DEG and a drawing speed of 300 mm/min.

Adhesive force N ₅₀ [N/25mm]The following is held: the pressure-bonded part was held at 50 ℃ for 30 minutes in an atmosphere of 50 ℃ and then left at 23 ℃ for 30 minutes in a 50% RH atmosphere, and then the 180 DEG peel adhesion was measured under conditions of a peel angle of 180 DEG and a tensile rate of 300mm/min in the atmosphere.

Adhesive force N ₈₀ [N/25mm]The following is held: the adhesive sheet was pressure-bonded to a SUS plate as an adherend, heated at 80 ℃ for 5 minutes, and then left to stand at 23 ℃ and 50% RH for 30 minutes, and then the 180 DEG peel adhesion was measured under conditions of a peel angle of 180 DEG and a tensile rate of 300mm/min under these conditions.

As an adherend, in the adhesive force N ₂₃ 、N ₅₀ 、N ₈₀ In any of the measurements, SUS304BA plate was used. In the measurement, an appropriate backing material (for example, a PET film having a thickness of about 25 μm) is attached to the pressure-sensitive adhesive sheet to be measured and reinforced as necessary. Adhesive force N ₂₃ 、N ₅₀ 、N ₈₀ More specifically, the measurement can be carried out by the method described in the following examples.

In several ways, the adhesive force N ₂₃ For example, it may be 3N/25mm or less, preferably 2.5N/25mm or less, more preferably less than 2N/25mm, and may be 1.5N/25mm or less, may be 1.2N/25mm or less, or may be 1N/25mm or less. Adhesive force N ₂₃ Lower is preferable from the viewpoint of reworkability. Adhesive force N ₂₃ The lower limit of (B) is not particularly limited, but may be, for example, 0.01N/25mm or more. The adhesive force N is a force to prevent positional deviation before the increase of the adhesive force from the viewpoint of workability of adhesion to an adherend, and the like ₂₃ Usually, it is preferably 0.1N/25mm or more. In some embodiments, the adhesive force N is ₂₃ For example, it may be 0.2N/25mm or more, 0.3N/25mm or more, 0.4N/25mm or more, or 0.5N/25mm or more.

In several ways, the adhesive force N ₅₀ For example, it may be 8N/25mm or less, preferably 7N/25mm or less, more preferablyIt is preferably 5N/25mm or less, and may be 4.5N/25mm or less, and may be 4N/25mm or less, or may be less than 4N/25 mm. Adhesive force N ₅₀ A low content is preferable from the viewpoint of exhibiting good reworkability even in a use mode in which a temperature of about 50 ℃ may be applied at the initial stage of attachment. Adhesive force N ₅₀ The lower limit of (B) is not particularly limited, but may be, for example, 0.05N/25mm or more. The adhesive force N is a force to prevent positional deviation before the increase of the adhesive force ₅₀ Usually, it is preferably 0.1N/25mm or more. From the viewpoint of improving the adhesive force after heating, etc., the adhesive force N is ₅₀ For example, it may be 0.5N/25mm or more, 1N/25mm or more, or 1.5N/25mm or more.

In several ways, the adhesive force N ₈₀ The (adhesive force after heating) may be, for example, 5N/25mm or more, 7N/25mm or more, 10N/25mm or more, 13N/25mm or more, 15N/25mm or more, or 17N/25mm or more. The upper limit of the adhesive force after heating is not particularly limited. In some embodiments, the adhesive strength after heating may be, for example, 70N/25mm or less, 50N/25mm or less, or 40N/25mm or less, from the viewpoint of ease of production and economy of the adhesive sheet.

The adhesive strength of the adhesive sheet disclosed herein after heating is one characteristic of the adhesive sheet, and is not limited to the use mode of the adhesive sheet. In other words, the use of the pressure-sensitive adhesive sheet disclosed herein is not limited to the method of heating at 80 ℃ for 5 minutes, and for example, the pressure-sensitive adhesive sheet may be used without particularly performing a treatment of heating to a room temperature range (usually 20 ℃ to 30 ℃, typically 23 ℃ to 25 ℃) or higher. In this usage, the adhesive force is also increased for a long period of time, and a strong joint can be achieved. In addition, the adhesive sheet disclosed herein can promote the increase in adhesive force by performing a heat treatment at a temperature higher than 50 ℃ at any time after the 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 substrate of the pressure-sensitive adhesive sheet, adherend, and the like. The heating temperature may be, for example, less than 150 ℃ or not more than 120 ℃, not more than 100 ℃, not more than 80 ℃, or not more than 70 ℃. The heating temperature may be 55 ℃ or higher, 60 ℃ or higher, or 70 ℃ or higher, 80 ℃ or higher, or 100 ℃ or higher, for example. With a higher heating temperature, the adhesive force can be increased by a shorter time of treatment. 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 a limit that the pressure-sensitive adhesive sheet or the adherend is not significantly thermally deteriorated. The heating treatment may be performed at one time or may be performed in a plurality of times.

The adhesive sheet disclosed herein is obtained by adjusting the Mw of the polymer B to 7X 10 ⁴ Above (preferably 8 × 10) ⁴ Above, more preferably 10 × 10 ⁴ Above, e.g. more than 10X 10 ⁴ ) Not only exhibits low initial adhesiveness in a room temperature region (e.g., 23 ℃) and strong adhesiveness after an increase in adhesive strength, but also easily improves the adhesive strength in a high temperature region (e.g., 80 ℃) relative to the adhesive strength N in a room temperature region after an increase in adhesive strength ₈₀ Maintenance ratio of (2). In several ways, the adhesion N at 80 ℃ _H [N/25mm]With respect to the adhesive force N ₅₀ [N/25mm]Maintenance ratio of (i.e. N) _H /N ₈₀ (hereinafter, also referred to as "heat-resistant adhesive force maintenance ratio") is favorably more than 10%, preferably 12% or more, more preferably 15% or more, and may be 17% or more, or may be 20% or more. From the viewpoint of heat resistance of the adhesive sheet, N _H /N ₈₀ The higher the more preferred. Thus, N _H /N ₈₀ The upper limit of (b) is not particularly limited, but is typically 100% or less.

Here, adhesive force N _H (hereinafter, also referred to as 80 ℃ adhesive force.) is grasped as follows: after being pressure-bonded to a SUS plate as an adherend and held at 80 ℃ for 30 minutes, the 180 ° peel adhesion was measured under conditions of a peel angle of 180 degrees and a tensile speed of 300mm/min under the environment (i.e., at 80 ℃).

As an adherend, the adhesive force N ₂₃ The measurement of (2) was carried out by using SUS304BA plate. In the measurement, an appropriate backing material (for example, a PET film having a thickness of about 25 μm) may be attached to the pressure-sensitive adhesive sheet to be measured and reinforced as necessary. Adhesive force N _H More specifically, the measurement can be carried out by the method described in the examples below.

In several ways, the adhesive force N _H For example, it may be 3N/25mm or more, 3.5N/25mm or more, or 4N/25mm or more. Adhesive force N _H Higher means that after the adhesive force is increased, a highly reliable bond can be maintained even in a high temperature region. Adhesive force N _H The upper limit of (B) is not particularly limited, and the higher the content of (B) is, the more preferable from the viewpoint of heat resistance, the lower the content of (B) is, typically, 40N/25mm or less, and from the viewpoint of easy compatibility with the initial low adhesiveness, 30N/25mm or less, or 20N/25mm or less may be used.

(adhesive sheet with substrate)

When the psa sheet disclosed herein is in the form of a psa sheet with a substrate, the thickness of the psa sheet may be, for example, 1000 μm or less, 600 μm or less, 350 μm or less, or 250 μm or less. From the viewpoint of downsizing, weight saving, thickness reduction, and the like of a product to which the pressure-sensitive adhesive sheet is applied, in some embodiments, 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 handling properties and the like, the thickness of the pressure-sensitive adhesive sheet may be, for example, 5 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, or 30 μm or more. In some embodiments, the thickness of the pressure-sensitive adhesive sheet may be, for example, 50 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, or 120 μm or more. The upper limit of the thickness of the adhesive sheet is not particularly limited.

The thickness of the pressure-sensitive adhesive sheet is the thickness of the portion to be attached to the adherend. For example, in the psa sheet 1 having the structure shown in fig. 1, the thickness from the psa surface 21A of the psa sheet 1 to the second surface 10B of the substrate 10 does not include the thickness of the release liner 31.

The adhesive sheet disclosed herein can be suitably implemented, for example, in such a manner that the thickness Ts of the support substrate is larger than the thickness Ta of the adhesive layer, that is, Ts/Ta is larger than 1. Although not particularly limited, Ts/Ta may be, for example, 1.1 or more, 1.2 or more, 1.5 or more, or 1.7 or more. For example, in an adhesive sheet that can be used for the purpose of reinforcing, supporting, impact-reducing an adherend, etc., by increasing Ts/Ta, it is likely that a good effect will be exhibited even if the adhesive sheet is made thin. In some embodiments, Ts/Ta may be 2 or more (e.g., greater than 2), 2.5 or more, or 2.8 or more. Further, Ts/Ta may be 50 or less, or 20 or less, for example. From the viewpoint of easily exhibiting high post-heating adhesive strength even when the adhesive sheet is made thin, Ts/Ta may be, for example, 10 or less, 8 or less, or 5 or less.

The adhesive layer is preferably fixed to a support base. Here, fixation means: in the pressure-sensitive adhesive sheet having an increased adhesive force after being attached to an adherend, sufficient anchorage of the pressure-sensitive adhesive layer to a support substrate is exhibited to such an extent that peeling at the interface between the pressure-sensitive adhesive layer and the support substrate does not occur when the pressure-sensitive adhesive sheet is peeled from the adherend. When the pressure-sensitive adhesive sheet with a base material is fixed to a support base material by the pressure-sensitive adhesive layer, the adherend and the support base material can be firmly integrated. As a preferable example of the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is fixed to the substrate, there is a pressure-sensitive adhesive sheet in which peeling (anchor breakage) does not occur between the pressure-sensitive adhesive layer and the support substrate at the time of measuring the adhesive strength after heating. A pressure-sensitive adhesive sheet having a post-heating adhesive force of 15N/25mm or more and not causing anchor failure when the post-heating adhesive force is measured is a preferable example of a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is fixed to a substrate.

The adhesive sheet disclosed herein can be more preferably manufactured by, for example, a method comprising the following steps in order: a liquid adhesive composition is brought into contact with a first surface of a substrate, and the adhesive composition is cured on the first surface to form an adhesive layer. 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. In the method of forming the pressure-sensitive adhesive layer by curing the liquid pressure-sensitive adhesive composition on the first surface of the substrate in this manner, the anchoring property of the pressure-sensitive adhesive layer to the substrate can be improved as compared with a method of arranging the pressure-sensitive adhesive layer on the first surface of the substrate by bonding the cured pressure-sensitive adhesive layer to the first surface of the substrate. This makes it possible to favorably produce a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is fixed to the substrate.

In some embodiments, as a method of bringing a 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 (pressure-sensitive adhesive surface) of the pressure-sensitive adhesive layer cured on the first surface of the substrate into contact with the release surface, a pressure-sensitive adhesive sheet having a structure in which the second surface of the pressure-sensitive adhesive layer is fixed to the first surface of the substrate and the first surface of the pressure-sensitive adhesive layer is brought into contact with the release surface can be obtained. As the release surface, a surface of a release liner, a back surface of a base material subjected to a release treatment, or the like can be used.

In the case of a photocurable pressure-sensitive adhesive composition using a partial polymer (polymer slurry) of a monomer raw material, for example, the pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition to a release surface, covering the first surface of a substrate with the applied pressure-sensitive adhesive composition, bringing the uncured pressure-sensitive adhesive composition into contact with the first surface of the substrate, and irradiating the pressure-sensitive adhesive composition sandwiched between the first surface of the substrate and the release surface with light to cure the pressure-sensitive adhesive composition.

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

In the case where the psa sheet disclosed herein is in the form of a psa sheet having a first psa layer provided on a first surface of a substrate and a second psa layer provided on a second surface of the substrate (i.e., a psa sheet with a substrate that is double-sided adhesive), the first psa layer and the second psa layer may have the same configuration or different configurations. When the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer have different structures, the difference may be, for example, a difference in composition or a difference in structure (thickness, surface roughness, formation range, formation pattern, or the like). For example, the second adhesive layer may be an adhesive layer that does not contain polymer B. N on the surface (second adhesive surface) of the second adhesive layer ₈₀ /N ₅₀ May be less than 3, may be less than 2, may be less than 1.5, and may be less than 1.

< Release liner-Equipped adhesive sheet >

The pressure-sensitive adhesive sheet disclosed herein may be in the form of a pressure-sensitive adhesive article 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-lined pressure-sensitive adhesive sheet (pressure-sensitive adhesive article) including any of the pressure-sensitive adhesive sheets disclosed herein and a release liner having a release surface that comes into contact with the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet can be provided.

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

The release liner is not particularly limited, and examples thereof include a release liner having a release layer on the surface of a liner base material such as a resin film or paper (which may be paper laminated with a resin such as polyethylene), and a release liner comprising 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). 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, or a release liner including a resin film made 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 a polyethylene film, a polypropylene film, a polybutylene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyester film (e.g., a PET film and a PBT film), a polyurethane film, and an ethylene-vinyl acetate copolymer film. For forming the release layer, for example, a known release treatment agent such as a silicone release treatment agent, a long-chain alkyl release treatment agent, an olefin release treatment agent, a fluorine release treatment agent, a fatty acid amide release treatment agent, molybdenum sulfide, or silica powder can be used. Particularly, a silicone-based release treating agent is preferably used.

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

< use >

The pressure-sensitive adhesive sheet provided in the present specification, for example, can contribute to suppression of a decrease in yield and improvement in the quality of a product including the pressure-sensitive adhesive sheet, because the adhesive strength is suppressed to be low for a while in a temperature range from room temperature to about 50 ℃ (for example, 20 ℃ to 50 ℃) after the pressure-sensitive adhesive sheet is bonded to an adherend, and good reworkability can be exhibited during this period. Further, the adhesive sheet can be cured (may be heated to a temperature higher than 50 ℃, with time, a combination thereof, or the like) to greatly increase the adhesive strength. For example, the pressure-sensitive adhesive sheet can be firmly adhered to an adherend by heating at a desired timing. By utilizing this feature, the adhesive sheet disclosed herein can be preferably used for the purposes of fixing, joining, forming, decorating, protecting, reinforcing, supporting, impact-mitigating, and the like of members included in various products in various fields.

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

For example, in optical members used in optical products and electronic members used in electronic products, high integration, reduction in size and weight, and thinning are in progress, and there is a possibility that a plurality of thin optical members/electronic members having different line expansion coefficients and thicknesses are laminated. By attaching the reinforcing film as described above to such a member, appropriate rigidity can be imparted to the optical member and the electronic member. Thus, in the manufacturing process and/or the manufactured product, curling and bending due to stress that may occur between the plurality of members having different linear expansion coefficients and thicknesses can be suppressed.

In the process for producing an optical product or an electronic product, in the aspect of performing shape processing such as cutting processing on a thin optical member or an electronic member as described above, by applying a reinforcing thin film to the member, local stress concentration on the optical member or the electronic member due to the processing can be alleviated, and the risk of cracking, breaking, peeling of the laminated member, and the like can be reduced. The process of attaching the reinforcing member to the optical member/electronic member can also contribute to relaxation of local stress concentration at the time of conveyance, lamination, rotation, or the like of the member, and suppression of bending, or the like of the member due to its own weight.

Further, even when a device such as an optical product or an electronic product including the reinforcing film is used by a consumer in the market, the device can be made to include the reinforcing film to alleviate a stress applied to the device when an unintended stress is applied thereto, such as when the device is dropped, placed under a heavy object, or hit by a flying object. Therefore, by including the reinforcing film in the above device, the durability of the device can be improved.

The adhesive sheet disclosed herein can be preferably used to be attached to members constituting various portable devices (portable electronic devices), for example. "portable" here is merely interpreted as insufficient to be portable, which means having a level of portability that an individual (a standard adult) can carry with relative ease. Examples of the portable device include a mobile phone, a smart phone, a tablet personal computer, a notebook personal computer, various wearable devices, a digital camera, a digital video camera, an audio device (such as a portable music player and an IC recorder), a calculator (such as a desktop calculator), a portable game device, an electronic dictionary, an electronic notebook, an electronic book, a vehicle-mounted information device, a portable electronic device such as a portable radio, a portable television, a portable printer, a portable scanner, and a portable modem, and a wristwatch, a pocket watch, a flashlight, and a wristwatch. Examples of the member constituting the portable electronic device include an optical film, a display panel, and the like used for an image display device such as a thin-layer display such as a liquid crystal display, a thin-film display, and the like. The pressure-sensitive adhesive sheet disclosed herein can also be preferably used to adhere to various members in automobiles, home electric appliances, and the like.

The matters disclosed in the present specification include the following.

(1) An adhesive sheet comprising an adhesive layer,

the pressure-sensitive adhesive layer contains a polymer A as a polymer of a monomer raw material A and a polymer B as a polymer of a monomer raw material B,

the monomer raw material B contains a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer,

the weight average molecular weight of the above polymer B was 7X 10 ⁴ In the above-mentioned manner,

the adhesive sheet was adhered to a stainless steel plate and held at 50 ℃ for 30 minutes, and then the adhesive force N was measured at 23 ℃ ₅₀ And the adhesive force N measured at 23 ℃ after being bonded to a stainless steel plate and heated at 80 ℃ for 5 minutes ₈₀ Satisfies the following equation:

(N ₈₀ /N ₅₀ )≥3。

(2) the adhesive sheet according to the item (1), wherein the adhesive force N is ₅₀ And the adhesive force N measured at 23 ℃ after being attached to a stainless steel plate and left at 23 ℃ for 30 minutes ₂₃ Also satisfies the following equation:

(N ₅₀ /N ₂₃ )＜10。

(3) the adhesive sheet according to the above (1) or (2), wherein the adhesive force N is ₈₀ Adhesive force N measured at 80 ℃ after being bonded to a stainless steel plate and kept at 80 ℃ for 30 minutes _H Satisfies the following equation:

(N _H /N ₈₀ )≥15％。

(4) the adhesive sheet according to any one of the above (1) to (3), which further satisfies the following formula:

(N ₈₀ /N ₂₃ )≥15。

(5) the adhesive sheet according to any one of the above (1) to (4), wherein the adhesive force N is ₂₃ Is 2N/25mm or less.

(6) The adhesive sheet according to any one of (1) to (5) above, wherein the adhesive force N is ₅₀ Is 8N/25mm or less.

(7) The method according to any one of the above (1) to (6)The adhesive sheet of (1), wherein the adhesive force N ₈₀ Is 15N/25mm or more.

(8) The adhesive sheet according to any one of the above (1) to (7), wherein the adhesive force NH is 3N/25mm or more.

(9) The adhesive sheet according to any one of the above (1) to (8), wherein the functional group equivalent of the monomer having a polyorganosiloxane skeleton is 700g/mol or more and less than 15000 g/mol.

(10) The adhesive sheet according to any one of the above (1) to (9), wherein the content of the monomer having a polyorganosiloxane skeleton in the monomer raw material B is 10 wt% or more and 60 wt% or less.

(11) The adhesive sheet according to any one of the above (1) to (10), wherein the (meth) acrylic monomer contained in the monomer raw material B contains a monomer M2 having a homopolymer glass transition temperature of 50 ℃ or higher.

(12) The pressure-sensitive adhesive sheet according to the item (11), wherein the monomer M2 contains one or more monomers selected from the group consisting of alkyl (meth) acrylates and (meth) acrylates having an alicyclic hydrocarbon group.

(13) The adhesive sheet according to the item (11), wherein the monomer M2 contains one or more alkyl (meth) acrylates.

(14) The adhesive sheet according to any one of the above (11) to (13), wherein the content of the monomer M2 in the monomer raw material B is 5 wt% or more and 80 wt% or less.

(15) The adhesive sheet according to any one of the above (1) to (14), wherein the (meth) acrylic monomer contained in the monomer raw material B contains a monomer M3 having a homopolymer glass transition temperature of-20 ℃ or higher and less than 50 ℃.

(16) The pressure-sensitive adhesive sheet according to the item (14), wherein the content of the monomer M3 in the monomer raw material B is 5 to 70 wt%.

(17) The adhesive sheet according to any one of the above (1) to (16), wherein the polymer B has a weight average molecular weight of 8X 10 ⁴ Above and notFoot 40 x 10 ⁴ 。

(18) The adhesive sheet according to any one of the above (1) to (17), 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.

(19) The adhesive sheet according to any one of (1) to (18) above, wherein the weight average molecular weight of the polymer a is 40 × 10 ⁴ The above.

(20) The adhesive sheet according to any one of the above (1) to (19), wherein the polymer a is an acrylic polymer.

(21) The adhesive sheet according to any one of the above (1) to (20), wherein the monomer raw material a contains a monomer having a nitrogen atom-containing ring.

(22) The pressure-sensitive adhesive sheet according to the item (21), wherein the monomer having a nitrogen atom-containing ring is an N-vinyl cyclic amide.

(23) The adhesive sheet according to the item (20), wherein the monomer raw material A contains a hydroxyl group-containing monomer.

(24) The adhesive sheet according to the item (20), wherein the monomer raw material A contains an N-vinyl cyclic amide and a hydroxyl group-containing monomer.

(25) The adhesive sheet according to any one of the above (1) to (24), wherein the adhesive layer contains a crosslinking agent in an amount of more than 0 part by weight and not more than 10 parts by weight based on 100 parts by weight of the polymer a.

(26) The adhesive sheet according to the item (25), wherein the crosslinking agent comprises an isocyanate-based crosslinking agent.

(27) The adhesive sheet according to any one of the above (1) to (26), wherein the thickness of the adhesive layer is 3 μm or more and 100 μm or less.

(28) The adhesive sheet according to any one of the above (1) to (27), which comprises a support base having a first surface and a second surface, wherein the adhesive layer is laminated on at least the first surface of the support base.

(29) A release-liner-equipped adhesive sheet comprising: the adhesive sheet according to any one of (1) to (28) above, and

and a release liner having a releasable surface in contact with the adhesive surface of the adhesive sheet.

(30) The release-liner-attached adhesive sheet according to the item (29), wherein the releasable surface is a surface of a release layer formed by a silicone-based release treatment agent.

Examples

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the specific examples. In the following description, "part" and "%" are based on weight unless otherwise specified.

(preparation of Polymer A1)

In a reaction vessel equipped with a stirring blade, a thermometer, a nitrogen introduction tube and a condenser, 60 parts of 2-ethylhexyl acrylate (2EHA), 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 in a nitrogen atmosphere, 0.2 part of 2,2' -Azobisisobutyronitrile (AIBN) as a thermal polymerization initiator was added, and a reaction was carried out at 60 ℃ for 6 hours to obtain a solution of polymer a 1. The Mw of this polymer A1 was 110 ten thousand.

(preparation of Polymer B1)

In a reaction vessel equipped with a stirring blade, a thermometer, a nitrogen introduction tube and a condenser, 40 parts of MMA, 20 parts of n-Butyl Methacrylate (BMA), 20 parts of 2-ethylhexyl methacrylate (2EHMA), 8.7 parts of a polyorganosiloxane skeleton-containing methacrylate monomer (trade name: X-22-174ASX, manufactured by shin-Etsu chemical Co., Ltd.) having a functional group equivalent of 900g/mol, 11.3 parts of a polyorganosiloxane skeleton-containing methacrylate monomer (trade name: KF-2012, manufactured by shin-Etsu chemical Co., Ltd.) having a functional group equivalent of 4600g/mol, 100 parts of ethyl acetate and 0.5 parts of thioglycerol as a chain transfer agent were charged, and after stirring at 70 ℃ for 1 hour under a nitrogen atmosphere, 0.2 parts of AIBN as a thermal polymerization initiator was charged, and after reaction at 70 ℃ for 2 hours, 0.1 weight of AIBN as a thermal polymerization initiator was chargedThe reaction was continued at 80 ℃ for 5 hours. Thus, a solution of polymer B1 was obtained. The Mw of this polymer B1 was 2.2X 10 ⁴ 。

(preparation of Polymer B2)

Mw was 7.5X 10 in the same manner as in the preparation of Polymer B1, except that the amount of thioglycerol used was changed to 0.1 part ⁴ Polymer B2.

(preparation of Polymer B3)

In the same manner as in the preparation of Polymer B1, except that thioglycerol was not used, an Mw of 16.5X 10 was obtained ⁴ Polymer B3.

(preparation of Polymer B4)

In a reaction vessel equipped with a stirring blade, a thermometer, a nitrogen inlet tube and a condenser, 40 parts of MMA, 20 parts of BMA, 20 parts of 2EHMA, 8.7 parts of a methacrylate monomer having a polyorganosiloxane skeleton with a functional group equivalent of 900g/mol (trade name: X-22-174ASX, manufactured by shin-Etsu chemical Co., Ltd.), 11.3 parts of a methacrylate monomer having a polyorganosiloxane skeleton with a functional group equivalent of 4600g/mol (trade name: KF-2012, manufactured by shin-Etsu chemical Co., Ltd.), and 82 parts of ethyl acetate were charged, and after stirring at 65 ℃ for 1 hour under a nitrogen atmosphere, 0.2 parts of AIBN was charged, after reacting at 65 ℃ for 4 hours, 0.1 parts by weight of AIBN was charged, and after continuing the reaction at 80 ℃ for 4 hours. Thus, Mw of 23.4X 10 was obtained ⁴ Polymer B4.

(preparation of Polymer B5)

Mw was 29.6X 10, which was the same as in the preparation of polymer B4, except that the amount of ethyl acetate used was changed to 67 parts ⁴ Polymer B5.

The weight average molecular weight of each polymer was measured under the following conditions using a GPC device (HLC-8220 GPC, manufactured by Tosoh corporation), and was determined in terms of polystyrene.

[ GPC conditions ]

The sample concentration: 0.2 wt% (tetrahydrofuran (THF) solution)

Sample injection amount: 10 μ l

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)

The detector: differential Refractometer (RI)

< production of adhesive sheet >

(example 1)

To a solution of polymer a1, 5 parts of polymer B1 and 2.5 parts of an isocyanate-based crosslinking agent (trade name: Takenate D110N, trimethylol propane xylylene diisocyanate, manufactured by mitsui chemical corporation) were added per 100 parts of polymer a1 contained in the solution, and the mixture was uniformly mixed to prepare a pressure-sensitive adhesive composition C1.

An adhesive composition C1 was directly applied to a first surface of a polyethylene terephthalate (PET) film (product of Toray corporation, trade name "Lumirror") having a thickness of 75 μm as a supporting substrate, and the film was heated at 110 ℃ for 2 minutes and dried to form an adhesive layer having a thickness of 25 μm. The release surface of the release liner is bonded to the surface (adhesive surface) of the pressure-sensitive adhesive layer. As the release liner, MRQ25T100 (a release liner having a release layer formed of a silicone-based release treatment agent on one surface of a polyester film, with a thickness of 25 μm) manufactured by mitsubishi chemical corporation was used. Thus, the pressure-sensitive adhesive sheet of example 1 was obtained as a release-lined pressure-sensitive adhesive sheet in which the release surface of the release liner was brought into contact with the pressure-sensitive adhesive surface.

(examples 2 to 8)

Adhesive compositions C2 to C8 were prepared in the same manner as in the preparation of adhesive composition C1, except that the type and amount of polymer B were changed as shown in table 1. Other than using these pressure-sensitive adhesive compositions C2 to C11, the pressure-sensitive adhesive sheets of examples 2 to 8 were obtained in the form of release-lined pressure-sensitive adhesive sheets in which the release surface of the release liner was brought into contact with the pressure-sensitive adhesive surface in the same manner as in the production of the pressure-sensitive adhesive sheet of example 1.

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

The pressure-sensitive adhesive sheets of the respective examples were cut into a width of 25mm together with a release liner, and the pressure-sensitive adhesive strength N was measured in the following order using a test piece and a SUS plate (SUS304BA plate) cleaned with toluene as an adherend ₂₃ Adhesive force N ₅₀ And adhesive force N ₈₀ 。

(adhesive force N) ₂₃ Measurement of (2)

The release liner covering the adhesive surface of each test piece was peeled off under a standard atmosphere of 23 ℃ and 50% RH, and a 2kg roller was reciprocated 1 time to bond the exposed adhesive surface to an adherend. After the test piece thus pressure-bonded to the adherend was left to stand in the above-mentioned standard environment for 30 minutes, a 180 ° peel adhesion (resistance to the above-mentioned stretching) was measured under conditions of a peel angle of 180 degrees and a stretching speed of 300mm/min in accordance with JIS Z0237 using a universal tensile compression tester (product name "tensile compression tester, TCM-1 kNB" manufactured by mineba). The measurement was conducted 3 times, and the average value of these was defined as the adhesive force N ₂₃ [N/25mm]Shown in table 1.

(adhesive force N) ₅₀ Measurement of (2)

Will pass through the adhesive force N ₂₃ The test piece pressure-bonded to the adherend was held at 50 ℃ for 30 minutes in the same manner as in the above measurement, and then left to stand in the above standard environment for 30 minutes, and thereafter, the 180 ° peel adhesion was similarly measured. The measurement was conducted 3 times, and the average value of these was defined as the adhesive force N ₅₀ [N/25mm]Shown in table 1.

(adhesive force N) ₈₀ Measurement of (2)

Will pass through the adhesive force N ₂₃ The test piece pressure-bonded to the adherend was heated at 80 ℃ for 5 minutes in the same manner as in the above measurement, and then left under the above standard environment for 30 minutes, and thereafter, the 180 ° peel adhesion was similarly measured. The measurement was conducted 3 times, and the average value of these was defined as the adhesive force N ₈₀ [N/25mm]Shown in table 1. It was confirmed that none of the pressure-sensitive adhesive sheets of examples 1 to 11 had the adhesive force N ₈₀ The measurement of (2) generates anchor destruction.

Adhesion at < 80 ℃ N _H Measurement of

Will pass through the adhesive force N ₂₃ The test piece pressure-bonded to the adherend was held at 80 ℃ for 30 minutes in the same manner as in the measurement of (3), and then the 180 ° peel adhesion was measured in the same manner as described above. The measurement was conducted 3 times, and the average value of them was defined as the adhesive force N at 80 ℃ _H [N/25mm]Shown in table 1.

Based on the results of the adhesion measurement, the adhesion increase ratio N was calculated ₈₀ /N ₅₀ And N ₅₀ /N ₂₃ And heat-resistant adhesive force maintenance ratio N _H /N ₈₀ . The results are shown in Table 1.

[ Table 1]

1) The amount of polymer B used relative to 100 parts by weight of polymer A

As shown in Table 1, it was confirmed that the Mw was 7X 10 ⁴ Examples 1 to 6 of the above polymers B by reacting N ₈₀ /N ₅₀ A temperature of 3 or more, and a low adhesiveness suitable for rework is maintained even when a temperature of about 50 ℃ is applied in an initial stage of the adhesion, and the adhesive strength can be greatly increased by heating at 80 ℃ for 5 minutes. Particularly good results were obtained with the adhesive sheets of examples 1 to 4.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The techniques recited in the claims include modifications and variations of 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 surface (second adhesive surface)

31, 32 release liners

100, 200, 300 Release liner-Equipped adhesive sheet (adhesive article)

Claims (9)

1. An adhesive sheet comprising an adhesive layer,

the adhesive layer contains a polymer A as a polymer of a monomer raw material A and a polymer B as a polymer of a monomer raw material B,

the monomer raw material B comprises: a monomer having a polyorganosiloxane skeleton and a (meth) acrylic monomer,

the weight-average molecular weight of the polymer B was 7X 10 ⁴ In the above-mentioned manner,

the adhesive sheet is attached to a stainless steel plate and held at 50 ℃ for 30 minutes, and then the adhesive force N measured at 23 DEG C ₅₀ A bonding force N measured at 23 ℃ after the pressure-sensitive adhesive sheet was adhered to a stainless steel plate and heated at 80 ℃ for 5 minutes ₈₀ Satisfies the following equation:

(N ₈₀ /N ₅₀ )≥3，

the amount of the polymer B used is more than 5 parts by weight relative to 100 parts by weight of the polymer A used,

the adhesive force N ₅₀ Adhesive force N measured at 23 ℃ after the adhesive sheet was attached to a stainless steel plate and left at 23 ℃ for 30 minutes ₂₃ Satisfies the following equation:

(N ₅₀ /N ₂₃ )＜7。

2. the adhesive sheet according to claim 1, wherein the adhesive force N ₈₀ A bonding force N measured at 80 ℃ after the adhesive sheet is adhered to a stainless steel plate and kept at 80 ℃ for 30 minutes _H Satisfies the following equation:

(N _H /N ₈₀ )≥15％。

3. the adhesive sheet according to claim 1 or 2, wherein the (meth) acrylic monomer contained in the monomer raw material B comprises a monomer M2 having a homopolymer glass transition temperature of 50 ℃ or higher.

4. The adhesive sheet according to claim 3, wherein the monomer M2 comprises an alkyl (meth) acrylate.

5. The adhesive sheet according to claim 1 or 2, wherein the content of the polymer B in the adhesive layer is more than 5 parts by weight and 50 parts by weight or less with respect to 100 parts by weight of the polymer a.

6. The adhesive sheet according to claim 1 or 2, wherein the polymer a is an acrylic polymer.

7. The adhesive sheet according to claim 1 or 2, wherein the monomer raw material a comprises: a monomer having a nitrogen atom-containing ring.

8. The adhesive sheet according to claim 1 or 2, wherein the adhesive layer contains more than 0 part by weight and 10 parts by weight or less of a crosslinking agent with respect to 100 parts by weight of the polymer a.

9. The adhesive sheet according to claim 1 or 2, 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.

Images