JP6830332B2 - Adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet.

In general, a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive; the same applies hereinafter) exhibits a soft solid state (viscoelastic body) in a temperature range near room temperature, and has a property of easily adhering to an adherend by pressure. Taking advantage of these properties, the pressure-sensitive adhesive is typically in the form of a pressure-sensitive adhesive sheet containing a pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive, and is used as a bonding means with good workability and high adhesion reliability, from home appliances to automobiles. , OA equipment, etc. are widely used in various industrial fields. As the base polymer of the pressure-sensitive adhesive, a polymer that exhibits rubber elasticity at room temperature is preferably used. An example of such a polymer is a polymer having a monomeric unit containing a carbon-carbon unsaturated bond (for example, a polymer having a monomeric unit based on a conjugated diene compound). Patent Document 1 describes a viscous adhesive composition containing a partially hydrogenated block copolymer having a vinyl aromatic monomer unit and a conjugated diene monomer unit (partially hydrogenated styrene-butadiene block copolymer, etc.). Has been done.

Japanese Unexamined Patent Publication No. 2016-35039

With the expansion of the fields of use and usage modes of adhesive sheets, the level of demand for long-term quality stability of adhesive sheets after production (hereinafter, also simply referred to as "quality stability") is increasing. In this respect, the pressure-sensitive adhesive sheet containing the pressure-sensitive adhesive using unsaturated rubber (particularly, the pressure-sensitive adhesive having a relatively high content of unsaturated rubber) still has room for improvement. In particular, when a tackifier resin is blended with an unsaturated rubber, deterioration such as a decrease in cohesive force (cohesiveness) tends to proceed, and the quality stability of the adhesive sheet tends to decrease.

Therefore, an object of the present invention is to provide an adhesive sheet having excellent long-term quality stability in a configuration including a pressure-sensitive adhesive having a composition in which an unsaturated rubber is mixed with a pressure-sensitive adhesive resin.

The pressure-sensitive adhesive sheet provided by this specification includes a pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive containing an unsaturated rubber and a pressure-sensitive adhesive resin. The pressure-sensitive adhesive has a weight average molecular weight Mw _H calculated from a molecular weight distribution curve based on gel permeation chromatography (GPC) measurement in a region where the polystyrene-equivalent molecular weight is 10,000 g / mol or more, and is aged at 80 ° C. for 4 weeks. The maintenance rate is 70% or more in the test. According to the technique disclosed here, the degree of deterioration of the pressure-sensitive adhesive can be accurately grasped by using the weight average molecular weight Mw _H as an index. An adhesive sheet having an Mw _H maintenance rate (hereinafter, also referred to as “Mw _H maintenance rate”) of 70% or more in the aging test can be excellent in quality stability. In addition, since it is permissible to add an adhesive resin to unsaturated rubber, according to the above adhesive sheet, both excellent adhesive properties (for example, tack and peel strength) and long-term quality stability can be achieved. Can be done.

In some embodiments, the content of the unsaturated rubber in the pressure-sensitive adhesive can be 30% by weight or more of the pressure-sensitive adhesive. As described above, the pressure-sensitive adhesive containing a relatively large amount of unsaturated rubber is advantageous for improving the pressure-sensitive adhesive properties, but on the other hand, it tends to deteriorate easily due to the unsaturated bond in the unsaturated rubber. According to the technique disclosed herein, it is possible to provide an adhesive sheet having good quality stability even in such a configuration.

In some embodiments, the content of the tackifier resin may be 10 parts by weight or more and 120 parts by weight or less with respect to 100 parts by weight of the unsaturated rubber. According to the pressure-sensitive adhesive having such a composition, excellent pressure-sensitive adhesive properties (for example, tack and peel strength) can be easily obtained. According to the technique disclosed herein, it is possible to provide a pressure-sensitive adhesive sheet having good quality stability even in a configuration using a pressure-sensitive adhesive having such a composition.

In some embodiments, the tackifier resin may include a phenolic tackifier resin. While the phenolic tackifier resin can contribute to the improvement of the adhesive properties, it tends to be a factor that promotes the deterioration of the pressure-sensitive adhesive. According to the technique disclosed herein, it is possible to provide a pressure-sensitive adhesive sheet having good quality stability even in a configuration containing a phenol-based pressure-sensitive adhesive resin. The content of the phenolic tackifier resin can be, for example, 5 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the unsaturated rubber. In such a composition, the effect of improving the adhesive properties by using the phenolic pressure-sensitive adhesive resin can be suitably exhibited. As the phenolic tackifier resin, for example, a terpene phenolic resin can be preferably adopted.

The technique disclosed herein can be preferably carried out in a embodiment in which the tackifier resin contains a phenol tackifier resin and the phenolic tackifier resin contains a terpenphenol resin having a hydroxyl value of 20 mgKOH / g or more. According to such a configuration, excellent adhesive properties and quality stability can be suitably compatible with each other.

The pressure-sensitive adhesive may further contain an anti-aging agent in addition to the unsaturated rubber and the pressure-imparting resin. The use of anti-aging agent, effectively increasing the Mw _H maintenance of the pressure-sensitive adhesive comprising a combination of a tackifying resin and an unsaturated rubber, to improve the long-term quality stability of the pressure-sensitive adhesive sheet (long life) be able to. As the anti-aging agent, for example, it is effective to use a radical scavenger and a sulfur-based antioxidant in combination. In addition, a phosphorus-based antioxidant may be used as the anti-aging agent. A higher effect can be exhibited by using a radical scavenger (for example, a phenolic antioxidant), a sulfur-based antioxidant, and a phosphorus-based antioxidant in combination.

In some embodiments, the pressure-sensitive adhesive preferably contains 30 parts by weight or less of the phenolic tackifier resin with respect to 100 parts by weight of the unsaturated rubber. The content of the phenolic tackifier resin may be 0 parts by weight, that is, the pressure-sensitive adhesive may not contain the phenolic tackifier resin. Thus, by limiting the upper limit of the content by paying attention to the amount of the phenol-based tackifying resins Among tackifying resins, effectively increasing the Mw _H maintenance of the pressure-sensitive adhesive, good quality stability An adhesive sheet (with a long life) can be provided.

In some embodiments, the unsaturated rubber has a monomeric composition comprising a conjugated diene compound, and the proportion of the conjugated diene compound in the monomer composition can be 70% by weight or more. As described above, the pressure-sensitive adhesive containing unsaturated rubber in which a large amount of conjugated diene compound is used can exhibit excellent pressure-sensitive adhesive properties in the composition containing the pressure-sensitive adhesive resin, but tends to deteriorate easily. According to the technique disclosed herein, it is possible to provide an adhesive sheet having good quality stability even in such a configuration.

In some embodiments, the unsaturated rubber may comprise a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound. A pressure-sensitive adhesive containing such a block copolymer and a pressure-sensitive adhesive resin can exhibit excellent pressure-sensitive adhesive properties. Therefore, according to the pressure-sensitive adhesive sheet provided with such a pressure-sensitive adhesive, excellent pressure-sensitive adhesive properties and quality stability can be suitably compatible with each other. As the block copolymer, those having a diblock ratio of 60% by weight or more can be preferably adopted from the viewpoint of tackiness, improvement of low temperature characteristics, and the like.

In some embodiments, the thickness of the pressure-sensitive adhesive layer can be 30 μm or greater. As the pressure-sensitive adhesive layer becomes thicker, the peel strength of the pressure-sensitive adhesive sheet tends to improve, but structural destruction (aggregation failure) inside the pressure-sensitive adhesive layer may easily occur. Therefore, it is particularly meaningful to apply the techniques disclosed herein to suppress the decrease in cohesiveness.

The technique disclosed herein is a double-sided adhesive sheet comprising a base material and a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer as the pressure-sensitive adhesive layers supported on both sides of the base material, respectively. It can be preferably carried out in the form. A double-sided adhesive sheet, that is, a double-sided adhesive sheet, is suitable for fixing members. In fixing the member, it is preferable to suppress a decrease in the cohesiveness of the adhesive for a long period of time after the adhesive sheet is attached, from the viewpoint of preventing the member from being displaced or falling off (eliminating the fixed state). Therefore, it is particularly meaningful to apply the techniques disclosed herein to suppress a decrease in the cohesiveness of the pressure-sensitive adhesive.

It is a schematic cross-sectional view which shows the structure of the pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet with a base material) which concerns on one Embodiment. It is a schematic cross-sectional view which shows the structure of the pressure-sensitive adhesive sheet (base-less double-sided pressure-sensitive adhesive sheet) which concerns on another embodiment. It is a schematic cross-sectional view which shows the structure of the pressure-sensitive adhesive sheet (single-sided pressure-sensitive adhesive sheet with a base material) which concerns on another embodiment.

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

As described above, the term "adhesive" as used herein refers to a material that exhibits a soft solid state (viscoelastic body) in a temperature range near room temperature and has the property of easily adhering to an adherend by pressure. .. The pressure-sensitive adhesive in the technique disclosed herein can also be grasped as a solid content of the pressure-sensitive adhesive composition or a component of the pressure-sensitive adhesive layer.

As used herein, the term "unsaturated rubber" refers to a polymer having a monomer unit containing a carbon-carbon unsaturated bond and exhibiting rubber elasticity at room temperature (for example, 23 ° C.). A typical unsaturated rubber contains a carbon-carbon unsaturated bond in the main chain.

In the present specification, the "block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound" refers to a monovinyl-substituted aromatic compound as a main monomer (a copolymer component exceeding 50% by weight; the same applies hereinafter). A polymer having at least one segment (hereinafter, also referred to as “A segment”) and a segment (hereinafter, also referred to as “B segment”) containing a conjugated diene compound as a main monomer. Generally, the glass transition temperature of the A segment is higher than the glass transition temperature of the B segment. As a typical structure of such a polymer, a copolymer having a triblock structure (triblock having an ABA structure) having A segments (hard segments) at both ends of the B segment (soft segment), one A Examples thereof include a diblock-structured copolymer (AB-structured diblock) composed of a segment and one B-segment.

As used herein, the term "styrene-based block copolymer" means a polymer having at least one styrene block. The styrene block refers to a segment containing styrene as a main monomer. The segment consisting substantially only of styrene is a typical example of the styrene block referred to here. Further, the "styrene isoprene block copolymer" refers to a polymer having at least one styrene block and at least one isoprene block (segment containing isoprene as a main monomer). Typical examples of styrene isoprene block copolymers are triblock structure copolymers (triblocks) having styrene blocks (hard segments) at both ends of the isoprene block (soft segment), one isoprene block and one styrene. Examples thereof include a diblock structure copolymer (diblock body) composed of blocks. The "styrene-butadiene block copolymer" refers to a polymer having at least one styrene block and at least one butadiene block (segment having butadiene as a main monomer).

In this specification, the "styrene content" of a styrene-based block copolymer refers to the weight ratio of the styrene component to the total weight of the block copolymer. The styrene content can be measured by NMR (Nuclear Magnetic Resonance Spectral Method).
Further, the ratio of the diblock compound to the styrene block copolymer (hereinafter, may be referred to as "diblock compound ratio" or "diblock ratio") is determined by the following method. That is, a styrene-based block copolymer is dissolved in tetrahydrofuran (THF), and a total of 4 stages of GS5000H and G4000H liquid chromatograph columns manufactured by Toso Co., Ltd. are connected in series, and THF is used as the mobile phase. Then, high performance liquid chromatography is performed under the conditions of a temperature of 40 ° C. and a flow rate of 1 mL / min. From the obtained chart, the peak area corresponding to the diblock body is measured. Then, the diblock body ratio can be obtained by calculating the percentage of the peak area corresponding to the diblock body with respect to the total peak area.

In this specification, a numerical value representing a molecular weight or a weight average molecular weight is understood as a numerical value with a unit of "g / mol" unless otherwise specified. Further, the molecular weight related to the GPC measurement shall mean the polystyrene-equivalent molecular weight unless otherwise specified.

<Structural example of adhesive sheet>
The pressure-sensitive adhesive sheet disclosed herein (which may be in the form of a long tape or the like) may be, for example, in the form of a double-sided pressure-sensitive adhesive sheet having the cross-sectional structure shown in FIG. The double-sided pressure-sensitive adhesive sheet 1 includes a base material (for example, a plastic film or a non-woven fabric) 15 and a first pressure-sensitive adhesive layer 11 and a second pressure-sensitive adhesive layer 12 supported on both sides of the base material 15, respectively. More specifically, the first adhesive layer 11 and the second adhesive layer 12 are provided on the first surface 15A and the second surface 15B (both are non-peelable) of the base material 15, respectively. As shown in FIG. 1, the double-sided adhesive sheet 1 before use (before being attached to the adherend) is spirally wound by overlapping the front surface 21A and the back surface 21B with the release liner 21 which is a release surface. It can be in the form of In the double-sided adhesive sheet 1 of this form, the surface of the second adhesive layer 12 (second adhesive surface 12A) is peeled off by the front surface 21A of the release liner 21, and the surface of the first adhesive layer 11 (first adhesive surface 11A) is peeled off. Each is protected by the back surface 21B of the liner 21. Alternatively, the first adhesive surface 11A and the second adhesive surface 12A may be protected by two independent release liners, respectively.

The technique disclosed herein is preferably applied to a double-sided pressure-sensitive adhesive sheet with a base material as shown in FIG. 1, and a base-less (that is, has no base material) double-sided pressure-sensitive adhesive sheet 2 as shown in FIG. Can also be applied to. In the double-sided adhesive sheet 2 before use, for example, as shown in FIG. 2, the first adhesive surface 11A and the second adhesive surface 11B of the base material-less adhesive layer 11 are at least the surface (front surface) of the adhesive layer side. Can be in a form protected by peeling liners 21 and 22 having a peeling surface. Alternatively, the release liner 22 is omitted, a release liner 21 having both sides as release surfaces is used, and the release liner 11 is overlapped with the adhesive layer 11 and wound in a spiral shape so that the second adhesive surface 11B becomes a release liner. It may be in a form of being protected by being in contact with the back surface of the 21.

The technique disclosed herein is also a single-sided adhesive type group comprising a base material 15 and an adhesive layer 11 supported on a first surface (non-peeling surface) 15A of the base material, as shown in FIG. It can also be applied to the adhesive sheet 3 with a material. As shown in FIG. 3, for example, the adhesive sheet 3 before use has a release liner in which the surface (adhesive surface) 11A of the adhesive layer 11 is at least the surface (front surface) on the adhesive layer side as a release surface. It can be in the form protected by 21. Alternatively, the release liner 21 is omitted, the base material 15 having the second surface 15B as the release surface is used, and the pressure-sensitive adhesive sheet 3 with the base material is wound so that the first pressure-sensitive adhesive surface 11A is the second base material 15. It may be in a form of being protected by being in contact with the surface 15B.

The PSA sheet disclosed herein is characterized by comprising an adhesive layer made of a pressure-sensitive adhesive containing an unsaturated rubber and tackifying resins, and Mw _H maintenance of the pressure-sensitive adhesive is 70% or more .. Mw _H maintenance of the pressure-sensitive adhesive, the weight average molecular weight of the adhesive after 4 weeks aging test at 80 ° C. Mw H _(aging after Mw _H), weight average molecular weight of the adhesive in the previous該老trials Mw _H ( It is defined as the ratio to pre-aging Mw _H ). The aging test is carried out by storing an adhesive sheet having a release liner attached to the surface (adhesive surface) of the adhesive layer in an air atmosphere of 80 ° C. for 4 weeks. As the release liner, a release paper (for example, a release-treated polylami paper) can be preferably used. The thickness of the release liner is not particularly limited, and for example, one having a thickness of about 20 μm to 150 μm (typically about 25 μm to 100 μm) can be appropriately selected and used. The aging test can be carried out more specifically by the method described in Examples described later.

<Mw _H maintenance rate>
In this specification, the weight average molecular weight Mw _H of the pressure-sensitive adhesive (sometimes simply referred to as “Mw _H ”) means that the molecular weight in terms of polystyrene is 10,000 or more based on the molecular weight distribution curve obtained by GPC measurement. The weight average molecular weight calculated for a region. On the other hand, the weight average molecular weight calculated for the entire molecular weight distribution curve (that is, including the region where the polystyrene-equivalent molecular weight is less than 10,000) may be referred to as the weight average molecular weight Mw _T. As a sample for GPC measurement, the pressure-sensitive adhesive collected from the pressure-sensitive adhesive sheet is dissolved in tetrahydrofuran (THF) to prepare a 0.1% by weight solution, which is allowed to stand overnight and then filtered through a 0.45 μm membrane filter. Use the filtrate. GPC measurement can be performed under the following conditions or conditions in which equivalent results can be obtained. The same method is used in the examples described later.
-Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
-Column: TSKgel SuperHZM-H / HZ4000 / HZ3000 / HZ2000
-Column size: 6.0 mm I. D. × 150 mm
Eluent: THF
・ Flow rate: 0.6 mL / min
・ Detector: Differential refractometer (RI)
-Column temperature: 40 ° C
・ Injection amount: 20 μL
・ Standard sample: Polystyrene

In the pressure-sensitive adhesive containing an unsaturated rubber and a pressure-sensitive adhesive resin, a pressure-sensitive adhesive having a weight average molecular weight Mw _T lower than that of the unsaturated rubber is usually used. In the molecular weight distribution curve obtained by GPC measurement of such a pressure-sensitive adhesive, the peak corresponding to the pressure-sensitive adhesive resin typically appears in the region where the molecular weight is about several hundred to several thousand. According to the technique disclosed herein, the pressure-sensitive adhesive sheet by focusing on the weight average molecular weight Mw _H of the molecular weight distribution curve of the high molecular weight region (specifically, the region having a molecular weight of 10,000 or more) excluding such a region. It is possible to accurately grasp the deterioration and deterioration of unsaturated rubber that can cause deterioration of the quality of the rubber. According to the adhesive sheet having a retention rate (Mw _H retention rate) of 70% or more after the aging test of this weight average molecular weight Mw _H , excellent adhesive properties and long-term quality stability (for example, deterioration of cohesiveness with time) It is possible to achieve both (the property of having few).

In some embodiments, Mw _H maintenance rate may be at about 75% or more, may also be about 80% or more, may be about 85% or more. The art disclosed herein, embodiments and Mw _H maintenance rate is approximately 87% or more, can be preferably implemented in embodiments is about 90% or more. The closer the Mw _H maintenance rate is to 100%, the higher the quality stability of the adhesive sheet tends to be. Therefore, in the art disclosed herein, the upper limit of Mw _H maintenance rate may be 100%. Alternatively, in consideration of the balance and economics of other adhesive properties, from a practical point of view, Mw _H retention rate may be less than 100% (e.g. 99% or less). The Mw _H maintenance rate can be adjusted by, for example, selection of unsaturated rubber, amount of unsaturated rubber used, selection of tackifier resin, amount of tackifier resin used, and the like. Further, in the composition the adhesive agent comprises anti-aging agent, it can be selectively adjusted and antioxidants, the Mw _H retention ratio by the use of anti-aging agent.

Although not particularly limited, the Mw _H (that is, pre-aging Mw _H ) of the adhesive sheet disclosed herein is usually about 80,000 or more, and is about 100,000 or more. It may be about 130,000 or more, and may be about 150,000 or more. As the Mw _{H of the} pressure-sensitive adhesive sheet increases, the cohesiveness generally tends to improve. Further, the Mw _H of the adhesive sheet may be, for example, about 1,000,000 or less, about 800,000 or less, or about 600,000 or less. As the Mw _{H of the} pressure-sensitive adhesive sheet decreases, the tack and peel strength (particularly, these characteristics at low temperature, that is, low temperature characteristics) tend to improve in general. From this point of view, in some embodiments, the Mw _H of the pressure-sensitive adhesive sheet may be approximately 400,000 or less, may be approximately 300,000 or less, may be approximately 250,000 or less, and may be approximately 250,000 or less. It may be 200,000 or less. The technique disclosed herein can be suitably implemented, for example, in the form of an adhesive sheet having an Mw _H of approximately 130,000 or more and approximately 200,000 or less. The Mw _H of the adhesive sheet can be adjusted by selecting an unsaturated rubber or the like. Further, the composition containing the cross-linking agent can be adjusted by the type of the cross-linking agent and the amount of the cross-linking agent used.

Although not particularly limited, it is appropriate that the adhesive sheet disclosed herein has Mw _H after the aging test (that is, Mw _H after aging) of about 70,000 or more, and is about 90,000 or more. It is preferable that it is about 100,000 or more (for example, about 120,000 or more). When Mw _H becomes high after aging, better adhesive properties (for example, cohesiveness) tend to be exhibited even after a long period of time.

<Unsaturated rubber>
As the unsaturated rubber, various rubber-like polymers having a monomeric unit containing a carbon-carbon unsaturated bond can be used. In some embodiments, the unsaturated rubber can be a homopolymer or copolymer of a conjugated diene compound. Specific examples of the conjugated diene compound include 1,3-butadiene, isoprene and the like. The copolymer referred to here may be a random copolymer, a block copolymer, or a graft copolymer. Non-limiting examples of such unsaturated rubbers include natural rubber (NR), butadiene rubber (BR), styrene butadiene rubber (SBR), isobutene-isoprene rubber (IIR), acrylonitrile-butadiene rubber (NBR), Includes chloroprene rubber (CR), styrene isoprene block copolymers, styrene butadiene block copolymers and the like. In some embodiments, unsaturated rubbers with a monomeric composition containing isoprene can be preferably employed. Since the unsaturated rubber having such a monomer composition tends to easily undergo an autoxidation reaction due to the presence of the isoprene structure, it is of great significance to apply the technique disclosed herein.

In an unsaturated rubber having a monomer composition containing a conjugated diene compound, the ratio of the conjugated diene compound to the monomer composition is not particularly limited. From the viewpoint of improving the adhesive properties, the proportion of the conjugated diene compound can be, for example, 60% by weight or more, usually 65% by weight or more, preferably 70% by weight or more, and 75% by weight. It may be 80% by weight or more (typically more than 80% by weight, for example, 82% by weight or more). According to the technique disclosed herein, even in a pressure-sensitive adhesive using an unsaturated rubber having a monomer composition containing a large amount of a conjugated diene compound, a pressure-sensitive adhesive sheet having good quality stability can be provided.

(Block copolymer of monovinyl-substituted aromatic compound and conjugated diene compound)
In some embodiments, the unsaturated rubber may contain a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound. The monovinyl-substituted aromatic compound refers to a compound in which one functional group having a vinyl group is bonded to an aromatic ring. A typical example of the aromatic ring is a benzene ring (which may be a benzene ring substituted with a functional group having no vinyl group (for example, an alkyl group)). Specific examples of the monovinyl-substituted aromatic compound include styrene, α-methylstyrene, vinyltoluene, vinylxylene and the like. Specific examples of the conjugated diene compound include 1,3-butadiene, isoprene and the like. Such block copolymers can be used alone or in combination of two or more as unsaturated rubbers in the techniques disclosed herein.

In the A segment (hard segment) of the block copolymer, the copolymerization ratio of the monovinyl-substituted aromatic compound (two or more thereof can be used in combination) is 70% by weight or more (more preferably 90% by weight or more). It may be substantially 100% by weight.). In the B segment (soft segment) of the block copolymer, the copolymerization ratio of the conjugated diene compound (two or more thereof can be used in combination) is 70% by weight or more (more preferably 90% by weight or more), which is substantially the same. It may be 100% by weight.). According to such a block copolymer, a higher performance pressure-sensitive adhesive sheet can be realized.

The block copolymer may be in the form of a diblock body, a triblock body, a radial body, a mixture thereof, or the like. In the triblock body and the radial body, it is preferable that the A segment (for example, styrene block) is arranged at the end of the polymer chain. This is because the A segments arranged at the ends of the polymer chains are likely to gather to form a domain, thereby forming a pseudo crosslinked structure and improving the cohesiveness of the pressure-sensitive adhesive.
As the block copolymer in the technique disclosed herein, the diblock ratio is 30% by weight or more (more preferably 40% by weight or more, still more preferably 50%) from the viewpoint of adhesive strength (peeling strength) to the adherend. By weight% or more, particularly preferably 60% by weight or more, typically 65% by weight or more) can be preferably used. From the viewpoint of peel strength, a block copolymer having a diblock ratio of 70% by weight or more is particularly preferable. Further, from the viewpoint of cohesiveness and the like, a block copolymer having a diblock compound ratio of 90% by weight or less (more preferably 85% by weight or less, for example 80% by weight or less) can be preferably used. For example, a block copolymer having a diblock ratio of 60 to 85% by weight is preferable, and a block copolymer having a diblock ratio of 70 to 85% by weight (for example, 70 to 80% by weight) is more preferable.

(Styrene block copolymer)
In a preferred embodiment of the technique disclosed herein, the unsaturated rubber is a styrene-based block copolymer. For example, it is preferable that the unsaturated rubber contains at least one of a styrene isoprene block copolymer and a styrene butadiene block copolymer. Of the styrene-based block copolymers contained in the pressure-sensitive adhesive, the proportion of styrene-isoprene block copolymer is 70% by weight or more, the proportion of styrene-butadiene block copolymer is 70% by weight or more, or styrene. The total ratio of the isoprene block copolymer and the styrene-butadiene block copolymer is preferably 70% by weight or more. In a preferred embodiment, substantially all (eg, 95-100% by weight) of the styrene-based block copolymer is a styrene isoprene block copolymer. In another preferred embodiment, substantially all (eg, 95-100% by weight) of the styrene-based block copolymers are styrene-butadiene block copolymers. With such a composition, the effects of applying the techniques disclosed herein can be better exerted.

The styrene-based block copolymer may be in the form of a diblock body, a triblock body, a radial body, a mixture thereof, or the like. In the triblock body and the radial body, it is preferable that the styrene block is arranged at the end of the polymer chain. This is because the styrene blocks arranged at the ends of the polymer chains are likely to gather to form a styrene domain, thereby forming a pseudo crosslinked structure and improving the cohesiveness of the pressure-sensitive adhesive. The styrene-based block copolymer used in the technique disclosed herein has a diblock ratio of 30% by weight or more (more preferably 40% by weight or more) from the viewpoint of adhesive strength (peeling strength) to the adherend. More preferably 50% by weight or more, particularly preferably 60% by weight or more, typically 65% by weight or more) can be preferably used. A styrene-based block copolymer having a diblock ratio of 70% by weight or more (for example, 75% by weight or more) may be used. Further, from the viewpoint of cohesiveness and the like, a styrene-based block copolymer having a diblock compound ratio of 90% by weight or less (more preferably 85% by weight or less, for example 80% by weight or less) can be preferably used. From the viewpoint of achieving both adhesive properties and cohesiveness in a well-balanced manner, a styrene-based block copolymer having a diblock ratio of 60 to 85% by weight is preferable, and a styrene-based block copolymer having a diblock compound ratio of 70 to 85% by weight (for example, 70 to 80% by weight) is preferable. Block copolymers are more preferred.

The styrene content of the styrene-based block copolymer can be, for example, 5 to 40% by weight. From the viewpoint of cohesiveness, a styrene-based block copolymer having a styrene content of 10% by weight or more (more preferably more than 10% by weight, for example, 12% by weight or more) is preferable. From the viewpoint of peel strength, the styrene content is preferably 35% by weight or less (typically 30% by weight or less, more preferably 25% by weight or less), and 20% by weight or less (typically less than 20% by weight). , For example, 18% by weight or less) is particularly preferable. From the viewpoint of better exerting the effect of applying the technique disclosed herein, a styrene-based block copolymer having a styrene content of 12% by weight or more and less than 20% by weight can be preferably adopted.

(Content of unsaturated rubber)
In the pressure-sensitive adhesive disclosed herein, the content of the unsaturated rubber (for example, styrene isoprene block copolymer) as described above may be, for example, approximately 10% by weight or more of the entire pressure-sensitive adhesive, and is approximately 20% by weight. It may be% by weight or more. In some embodiments, the content of the unsaturated rubber in the pressure-sensitive adhesive may be approximately 30% by weight or more, may be approximately 40% by weight or more, and may be approximately 50% by weight or more. May be good. This makes it easier to form an adhesive sheet having more excellent adhesive properties. Further, as the content of the unsaturated rubber in the pressure-sensitive adhesive increases, the deterioration of the pressure-sensitive adhesive tends to proceed more easily, so that the effect of applying the technique disclosed herein can be better exhibited. From this point of view, the content of the unsaturated rubber may be about 55% by weight or more, or about 60% by weight or more. On the other hand, from the viewpoint of preferably exerting the effect of using the tackifier resin, the content of the unsaturated rubber in the pressure-sensitive adhesive is usually preferably about 95% by weight or less, and is about 90% by weight or less. It may be about 80% by weight or less, may be about 75% by weight or less, and may be about 70% by weight or less. The technique disclosed herein can also be preferably carried out in an embodiment in which the content of the unsaturated rubber is approximately 65% by weight or less (for example, approximately 60% by weight or less).

<Adhesive-imparting resin>
The pressure-sensitive adhesive layer disclosed herein contains a pressure-imparting resin in addition to the unsaturated rubber. The tackifier resin is selected from various known tackifier resins such as phenolic tackifier resins, terpene resins, modified terpene resins, rosin-based tackifier resins, petroleum resins, styrene resins, kumaron-inden resins, and ketone resins. One kind or two or more kinds to be used can be used. The tackifier resin is not particularly limited, but for example, a resin having a softening point of 40 ° C. or higher can be used, and a resin having a softening point of 60 ° C. or higher or 80 ° C. or higher is preferable. The softening point of the tackifier resin can be, for example, 200 ° C. or lower (typically 180 ° C. or lower).

The phenol-based tackifier resin referred to here means a tackifier resin having a molecular structure containing a phenol skeleton, and is a concept including a terpene phenol resin, a hydrogenated terpene phenol resin, a phenol resin, a rosin phenol resin and the like.
The terpene phenol resin refers to a polymer containing a terpene residue and a phenol residue, and is a copolymer of terpenes and phenols (terpene-phenol copolymer resin) and a homopolymer or copolymer of terpenes. It is a concept that includes both a phenol-modified product (phenol-modified terpene resin). Preferable examples of terpenes constituting such a terpene phenol resin are monoterpenes such as α-pinene, β-pinene, and limonene (including d-form, l-form, and d / l-form (dipentene)). Can be mentioned. The hydrogenated terpene phenol resin refers to a hydrogenated terpene phenol resin having a structure obtained by hydrogenating such a terpene phenol resin. It is also called hydrogenated terpene phenolic resin. Examples of the phenols include phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcin and the like.
The phenolic resin is typically a resin obtained from various phenols and formaldehyde as described above. Specifically, the phenol resin includes, for example, an alkylphenol resin, a xylene-formaldehyde resin, and the like. Examples of phenolic resins include the resol type obtained by adding and reacting the above-mentioned phenols and formaldehyde with an alkali catalyst, and the novolak type obtained by condensing the above-mentioned phenols and formaldehyde with an acid catalyst. included.
Rosin phenolic resins are typically phenolic forms of rosins or rosin derivatives, including rosin esters, unsaturated fatty acid modified rosins and unsaturated fatty acid modified rosin esters. Examples of the rosin phenol resin include a rosin phenol resin obtained by adding the above-mentioned phenols to rosins or rosin derivatives with an acid catalyst and thermally polymerizing them.

Examples of terpene resins include polymers of terpenes (typically monoterpenes) such as α-pinene, β-pinene, d-limonene, l-limonene and dipentene. It may be a homopolymer of one kind of terpenes or a copolymer of two or more kinds of terpenes. Examples of the homopolymer of one kind of terpenes include α-pinene polymer, β-pinene polymer, dipentene polymer and the like.

Examples of the modified terpene resin include modified terpene resins. Specific examples thereof include styrene-modified terpene resin and hydrogenated terpene resin.

The concept of a rosin-based tackifier resin here includes both rosins and rosin derivative resins.
Examples of rosins include unmodified rosins (raw rosins) such as gum rosins, wood rosins, and tall oil rosins; modified rosins obtained by modifying these unmodified rosins by hydrogenation, disproportionation, polymerization, etc. (hydrogenated rosins, non-modified rosins) Normalized rosin, polymerized rosin, other chemically modified rosins, etc.);
The rosin derivative resin is typically a derivative of the rosins as described above. The concept of a rosin-based resin as used herein includes derivatives of unmodified rosins and derivatives of modified rosins (including hydrogenated rosins, disproportionated rosins and polymerized rosins). For example, rosin esters such as unmodified rosin esters, which are esters of unmodified rosins and alcohols, and modified rosin esters, which are esters of modified rosins and alcohols; for example, unmodified rosins modified with unsaturated fatty acids. Saturated fatty acid-modified rosins; for example, unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; for example, rosins or various rosin derivatives described above (rosin esters, unsaturated fatty acid-modified rosins and unsaturated). Examples thereof include rosin alcohols obtained by reducing the carboxy group of (including fatty acid-modified rosin esters); for example, metal salts of rosins or various rosin derivatives described above. Specific examples of rosin esters include methyl esters of unmodified rosins or modified rosins (hydrogenated rosins, disproportionated rosins, polymerized rosins, etc.), triethylene glycol esters, glycerin esters, pentaerythritol esters, and the like.

Examples of petroleum resins include aliphatic (C5 series) petroleum resins, aromatic (C9 series) petroleum resins, aliphatic / aromatic copolymerized (C5 / C9 series) petroleum resins, and hydrogenated additives thereof ( For example, an aliphatic petroleum resin obtained by adding hydrogen to an aromatic petroleum resin) and the like.

Examples of styrene resins include those containing a styrene homopolymer as a main component, those containing an α-methylstyrene homopolymer as a main component, those containing a vinyltoluene homopolymer as a main component, styrene, and α. -Methylstyrene and vinyltorene containing two or more of them in the monomer composition as the main component (for example, α-methylstyrene / styrene copolymer containing α-methylstyrene / styrene copolymer as the main component) Combined resin) and the like.

As the kumaron-inden resin, a resin containing kumaron and inden as a monomer component constituting the skeleton (main chain) of the resin can be used. Examples of the monomer component that can be contained in the skeleton of the resin other than kumaron and indene include styrene, α-methylstyrene, methylindene, vinyltoluene and the like.

Examples of the ketone resin include a condensate of formaldehyde and ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetophenone, cyclohexanone, and methyl cyclohexanone.

As a preferred embodiment, an embodiment in which the pressure-sensitive adhesive layer contains one or more kinds of phenol-based tackifier resins (for example, terpene phenol resin) can be mentioned. By blending a phenol-based tackifier resin with an unsaturated rubber (for example, a styrene-based block copolymer), the tackiness properties can be effectively improved. As a result, an adhesive sheet having excellent adhesive properties and good long-term quality stability (long life) can be realized.
When the pressure-sensitive adhesive layer contains a phenol-based pressure-sensitive adhesive resin, the content thereof is not particularly limited. The content of the phenolic tackifier resin can be, for example, 1 part by weight or more with respect to 100 parts by weight of the unsaturated rubber, usually 5 parts by weight or more is appropriate, and even if it is 10 parts by weight or more. It may be 15 parts by weight or more. In some embodiments, the content of the phenolic tackifier resin with respect to 100 parts by weight of the unsaturated rubber may be 20 parts by weight or more, or 30 parts by weight or more (for example, 35 parts by weight or more). Further, from the viewpoint of low temperature characteristics and compatibility of the adhesive, the content of the phenolic tackifier resin with respect to 100 parts by weight of the unsaturated rubber is usually preferably 60 parts by weight or less, and 50 parts by weight or less. There may be. From the viewpoint of placing more importance on quality stability, in some embodiments, the content of the phenolic tackifier resin with respect to 100 parts by weight of the unsaturated rubber may be, for example, less than 40 parts by weight, and 35 parts by weight or less. It may be 30 parts by weight or less, or 25 parts by weight or less.

When a phenol-based tackifier resin is used, the amount of the phenol-based tackifier resin in the entire tackifier resin may be, for example, 25% by weight or more, 30% by weight or more, or 50% by weight or more. It may be 80% by weight or more, or 90% by weight or more. Substantially all of the tackifier resin (for example, 95 to 100% by weight, further 99 to 100% by weight) may be a phenolic tackifier resin. In such a configuration, the effect of using the phenolic tackifier resin can be suitably exhibited. Further, in some embodiments, the amount of the phenolic tackifier resin in the entire tackifier resin may be, for example, 70% by weight or less, and 60% by weight or less, from the viewpoint of improving low temperature characteristics and quality stability. It may be 45% by weight or less.

In some embodiments, the amount of the terpene phenolic resin in the total phenolic tackifier resin used can be, for example, 50% by weight or more, 70% by weight or more, or 85% by weight or more. It may be 90% by weight or more. Substantially all of the phenolic tackifier resins (eg, 95-100% by weight, even 99-100% by weight) may be terpene phenolic resins. The technique disclosed herein can be suitably carried out in such an embodiment to provide a pressure-sensitive adhesive sheet having good adhesive properties and a long life.

(Adhesive-imparting resin _TH )
PSA layer disclosed herein, as the tackifying resin, a softening point contains a tackifier resin T _H than 100 ° C.. From the viewpoint of aggregation property, the softening point of the tackifier resin _{T H,} preferably at least 120 ° C., more preferably at least 125 ° C., more preferably above 130 ° C., 135 ° C. or higher (e.g., 140 ° C. or higher) is especially preferred. Further, from the viewpoint of peel strength to the adherend, the softening point of the tackifier resin T _H, is suitably 200 ° C. or less, preferably 180 ° C. or less, more preferably 170 ° C. or less (e.g., 160 ° C. or less) is there.

Here, in this specification, the softening point of the tackifier resin is defined as a value measured based on the softening point test method (ring ball method) specified in JIS K5902 and JIS K2207. Specifically, the sample is melted as quickly as possible at the lowest possible temperature, and the ring placed on a flat metal plate is carefully filled to prevent bubbles. After cooling, use a slightly heated knife to cut off the raised part from the flat surface including the upper end of the ring. Next, a support (ring stand) is placed in a glass container (heating bath) having a diameter of 85 mm or more and a height of 127 mm or more, and glycerin is poured until the depth becomes 90 mm or more. Next, the steel ball (diameter 9.5 mm, weight 3.5 g) and the ring filled with the sample are immersed in glycerin without contacting each other, and the temperature of glycerin is kept at 20 ° C. plus or minus 5 ° C. for 15 minutes. .. Next, a steel ball is placed in the center of the surface of the sample in the ring and placed in place on the support. Next, the distance from the upper end of the ring to the glycerin surface is kept at 50 mm, a thermometer is placed, the center of the mercury bulb of the thermometer is set to the same height as the center of the ring, and the container is heated. The flame of the Bunsen burner used for heating should be between the center and the edge of the bottom of the container to equalize the heating. The rate at which the bath temperature rises after reaching 40 ° C. after the start of heating must be 5.0 plus or minus 0.5 ° C. per minute. The temperature at which the sample gradually softens and flows down from the ring and finally comes into contact with the bottom plate is read, and this is used as the softening point. Two or more softening points are measured at the same time, and the average value is adopted.

The tackifier resin T _H, the above-mentioned phenol-based tackifying resins, terpene resins, modified terpene resins, rosin-based tackifying resins, petroleum resins, styrene resins, coumarone-indene resin, one or two of such ketone resin The above can be used. Of these, terpene phenol resins, rosin phenol resins, terpene resins, polymerized rosins, and esterified products of polymerized rosins are preferable.

As a preferred embodiment, one or more terpene phenolic resins are used as the tackifier resin _TH1 . For example, more than 25% by weight of the tackifier resin _{T H} (more preferably 30 wt% or more) is a preferred embodiment terpene phenol resin (tackifier resin _{T H1).} Furthermore, terpene phenol resin amount in the tackifier resin T _H is 70 wt% or less approximately (e.g. 60 wt% or less, typically 50 wt% or less) may be. Alternatively, the tackifier resin _T less than 50% by weight of _H is may be a terpene phenol resin (tackifier resin _{T H1),} 80 wt% or more (e.g. 90 wt% or more) terpene phenol resin (tackifier resin _{T H1} ) is a also good, substantially all of the tackifier resin _{T H} (e.g. 95 to 100 wt%, more 99-100% by weight) may be a terpene phenol resin (tackifier resin _{T H1).} A terpene phenol resin having a softening point of 120 ° C. or higher and 200 ° C. or lower (typically 130 ° C. or higher and 180 ° C. or lower, for example, 135 ° C. or higher and 170 ° C. or lower) can be preferably adopted.

The proportion of the tackifier resin _{TH1 in} the total tackifier resin contained in the pressure-sensitive adhesive layer disclosed herein is not particularly limited. The above ratio can be, for example, 30% by weight or more (typically 40% by weight or more), and can be, for example, 70% by weight or less (typically 60% by weight or less). Alternatively, substantially all of the total tackifying resin (e.g., 95 to 100 wt%, more 99-100% by weight) may be a tackifier resin _{T H1.}

Furthermore, the art disclosed herein, as the tackifier resin T _{H, (typically} terpene phenolic resin) tackifier resin T _H1 may be preferably implemented in a manner that includes a different tackifier resin T _H2 and. The softening point of the tackifier resin T _H2 is lower it is preferable than the softening point of the tackifier resin T _H1, about 10 ° C. or higher (e.g., 20 ° C. or higher) than the softening point of the tackifier resin T _H1 is more preferably lower .. According to such an aspect, for example, an adhesive sheet having more excellent peel strength can be realized. From the viewpoint of achieving both cohesiveness and peel strength at a high level, a tackifier resin _TH2 having a softening point of 100 ° C. or higher and lower than 120 ° C. can be preferably adopted. Among them, the softening point is preferred to use a tackifier resin _{T H2} of less than 120 ° C. 110 ° C. or higher.

The tackifier resin _TH2 includes the above-mentioned various tackifier resins (phenol-based tackifier resin, terpene resin, modified terpene resin, rosin-based tackifier resin, petroleum resin, styrene resin, kumaron-inden resin, ketone resin, etc. ) Can be appropriately selected and used. The technique disclosed herein can be preferably carried out in a manner in which the pressure-sensitive adhesive contains at least one of a petroleum resin and a terpene resin as the pressure-sensitive adhesive resin _TH2 . For example, the main component of the tackifier resin T _H2 (i.e., component which accounts for 50 wt.% Of the tackifier resin T _H2) is the composition petroleum resin, composition is terpene resin, a petroleum resin and terpene resin A composition that is a combination, etc. can be preferably adopted. From the viewpoint of adhesive strength and compatibility, it is preferable that the main component of the tackifier resin _TH2 is a terpene resin (for example, α-pinene polymer or β-pinene polymer). Substantially all of the tackifier resin _TH2 (for example, 95% by weight or more) may be a terpene resin.

As the adhesive layer tackifier resin _{T H} disclosed herein, if it contains a tackifier resin _{T H1} and the tackifier resin _{T H2,} the relationship between their _usage, T _H1: weight ratio of _{T H2} 25 It is preferable to set it to be: 75 to 70:30 (more preferably 30:70 to 60:40). The art disclosed herein, the PSA can be preferably carried out in a manner including many T _H1 than T _H2 as a tackifying resin. According to such an aspect, a higher performance adhesive sheet can be realized.

Art disclosed herein, for example, as a tackifier resin _{T H,} the hydroxyl value may be preferably carried out in a manner containing 80 mg KOH / g or more (e.g. 90 mgKOH / g or higher) tackifying resin _{(T HO1).} The hydroxyl value of the tackifier resin _THO1 is typically 200 mgKOH / g or less, preferably 180 mgKOH / g or less (for example, 160 mgKOH / g or less). According to the pressure-sensitive adhesive containing the pressure-sensitive adhesive resin _THO1 , a higher-performance pressure-sensitive adhesive sheet can be realized. A pressure-sensitive adhesive sheet that has both cohesiveness and other properties (for example, low-temperature initial back adhesiveness) at a higher level can be realized.

Here, as the value of the hydroxyl value, a value measured by the potentiometric titration method specified in JIS K0070: 1992 can be adopted. The specific measurement method is as shown below.
[Measurement method of hydroxyl value]
1. 1. Reagent (1) As the acetylation reagent, about 12.5 g (about 11.8 mL) of acetic anhydride is taken, pyridine is added thereto to make the total volume 50 mL, and the reagent is sufficiently stirred. Alternatively, take about 25 g (about 23.5 mL) of acetic anhydride, add pyridine to this to make the total volume 100 mL, and use the one that has been sufficiently stirred.
(2) As a measurement reagent, a 0.5 mol / L potassium hydroxide ethanol solution is used.
(3) In addition, toluene, pyridine, ethanol and distilled water are prepared.
2. 2. Operation (1) Approximately 2 g of a sample is precisely collected in a flat-bottomed flask, 5 mL of an acetylation reagent and 10 mL of pyridine are added, and an air cooling tube is attached.
(2) The flask is heated in a bath at 100 ° C. for 70 minutes, allowed to cool, 35 mL of toluene is added as a solvent from the upper part of the cooling pipe and stirred, and then 1 mL of distilled water is added and stirred to obtain acetic anhydride. Disassemble. Heat again in the bath for 10 minutes to complete the decomposition and allow to cool.
(3) Wash the cooling tube with 5 mL of ethanol and remove it. Then, 50 mL of pyridine is added as a solvent and stirred.
(4) Add 25 mL of 0.5 mol / L potassium hydroxide ethanol solution using a whole pipette.
(5) Potentiometric titration is performed with a 0.5 mol / L potassium hydroxide ethanol solution. The inflection point of the obtained titration curve is used as the end point.
(6) In the blank test, perform the above (1) to (5) without inserting a sample.
3. 3. Calculation The hydroxyl value is calculated by the following formula.
Hydroxy group value (mgKOH / g) = [(BC) × f × 28.05] / S + D
here,
B: Amount (mL) of 0.5 mol / L potassium hydroxide ethanol solution used in the blank test,
C: Amount (mL) of 0.5 mol / L potassium hydroxide ethanol solution used for the sample,
f: Factor of 0.5 mol / L potassium hydroxide ethanol solution,
S: Sample weight (g),
D: Acid value,
28.05: 1/2 of the molecular weight of potassium hydroxide 56.11,
Is.

As the tackifier resin _THO1 , among the various tackifier resins described above, those having a hydroxyl value of a predetermined value or more can be used alone or in combination as appropriate. In a preferred embodiment, at least a terpene phenolic resin is used as the tackifier resin _THO1 . The terpene phenol resin is preferable because the hydroxyl value can be arbitrarily controlled by the copolymerization ratio of phenol. The proportion of terpene phenol resin occupying in the tackifier resin T _HO1 is approximately 50 wt% or more (e.g. 80 wt% or more, and typically 90% by weight or more), more preferably, substantially the tackifier resin T _HO1 It is more preferable that all of them (for example, 95 to 100% by weight, more preferably 99 to 100% by weight) are terpene phenol resins.

Art disclosed herein is, when implemented in a manner of using a pressure-sensitive adhesive layer containing a tackifier resin T _HO1, the proportion of the tackifier resin T _HO1 of the total tackifying resin is not particularly limited. The above ratio can be, for example, 10% by weight or more (typically 20% by weight or more), and can be, for example, 70% by weight or less (typically 60% by weight or less). Alternatively, substantially all (for example, 95 to 100% by weight, further 99 to 100% by weight) of the total tackifier resin may be the tackifier resin _THO1 .

PSA layer disclosed herein is as a tackifier resin _{T H,} a hydroxyl value of 0 or 80 mg KOH / g of less than tackifier resin _{(T HO2)} may contain. Tackifier resin _{T HO2} may be used in place of the tackifier resin _{T HO1,} it may be used in combination with a tackifier resin _{T HO1.} As a preferred embodiment, the hydroxyl value is a tackifier resin _{T HO1} above 80 mg KOH / g, include embodiments comprising a tackifier resin _{T HO2.}

As the tackifier resin _THO2 , among the various tackifier resins described above, those having a hydroxyl value in the above range can be used alone or in combination as appropriate. For example, a phenol-based tackifier resin having a hydroxyl value of 0 or more and less than 80 mgKOH / g (for example, terpene phenol resin or rosin phenol resin), petroleum resin (for example, C5-based petroleum resin), terpene resin (for example, β-pinene polymer). ), Rosins (for example, polymerized rosin), rosin derivative resins (for example, esterified products of polymerized rosin) and the like can be used. In a preferred embodiment, at least a terpene phenolic resin is used as the tackifier resin _THO2 . The terpene phenol resin is preferable because the hydroxyl value can be arbitrarily controlled by the copolymerization ratio of phenol. The ratio of the terpene phenol resin to the tackifier resin _THO2 may be about 50% by weight or more (for example, 80% by weight or more, typically 90% by weight or more), and the tackifier resin _THO2 is substantially. All (eg, 95-100% by weight, even 99-100% by weight) may be terpene phenolic resins.

Art disclosed herein is, when implemented in a manner of using a pressure-sensitive adhesive layer containing a tackifier resin T _HO2, the proportion of the tackifier resin T _HO2 of the total tackifying resin is not particularly limited. The above ratio can be, for example, 10% by weight or more (typically 20% by weight or more), and can be, for example, 70% by weight or less (typically 60% by weight or less). Alternatively, substantially all of the total tackifying resin (e.g., 95 to 100 wt%, more 99-100% by weight) may be a tackifier resin _{T HO2.}

The techniques disclosed herein include a tackifier resin _{THO1 in} which the pressure-sensitive adhesive layer has a hydroxyl value of 80 mgKOH / g or more (typically 80 to 160 mgKOH / g, for example, 80 to 140 mgKOH / g) and a hydroxyl value of 40 mgKOH / g. It can be preferably carried out in an embodiment including a tackifier resin _THO2 having a pressure of 80 mgKOH / g or more in combination. In this case, the relationship between the amounts of T _HO1 and T _{HO 2} used can be set, for example, so that the weight ratio (T _HO1 : T _{HO 2} ) is in the range of 1: 5 to 5: 1. It is appropriate to set it in the range of 3 to 3: 1 (for example, 1: 2 to 2: 1). As a preferred _{embodiment, T HO1,} T _HO2 is mentioned embodiment each a terpene phenol resin.

In one embodiment of the art disclosed herein, the tackifier resin _{T H} is as different tackifying resins and tackifying resin _{T HO1, T HO2,} has an aromatic ring and hydroxyl value is less than 30 mgKOH / g The tackifier resin _THR1 may be further contained. Examples of the tackifier resin having an aromatic ring include the above-mentioned aromatic petroleum resin, aliphatic / aromatic copolymer petroleum resin, styrene resin, kumaron-inden resin, styrene-modified terpene resin, and terpene-phenol copolymer. Examples thereof include resins, phenol-modified terpene resins, and rosinphenol resins. Among these, tackifier resins having a softening point of 120 ° C. or higher (preferably 130 ° C. or higher, for example 135 ° C. or higher) and a hydroxyl value of 30 mgKOH / g or lower (preferably less than 5 mgKOH / g, for example 1 mgKOH / g). It can be adopted as _THR1 . Among them, preferred tackifier resin _THR1 includes aromatic petroleum resin and styrene resin (for example, α-methylstyrene / styrene copolymer resin). The technique disclosed herein can also be carried out in a mode in which the pressure-sensitive adhesive layer does not substantially contain the tackifier resin _THR1 .

In another embodiment of the PSA disclosed herein, the tackifier resin T _H as tackifier resin T _HO1, different tackifying resins and T _HO2, has an aromatic ring and isoprene units, terpene skeleton and It may contain a tackifier resin _THR2 that is substantially free of rosin skeleton. Here, the fact that the tackifier resin _THR2 does not substantially contain the isoprene unit, the terpene skeleton and the rosin skeleton means that these structural parts (that is, the isoprene unit, the terpene skeleton and the rosin skeleton) account for the tackifier resin _THR2. Is less than 10% by weight in total (more preferably less than 8% by weight, still more preferably less than 5% by weight, for example less than 3% by weight). The above ratio may be 0% by weight. The ratio of the isoprene unit, the terpene skeleton and the rosin skeleton to the tackifier resin _THR2 can be measured by, for example, NMR (nuclear magnetic resonance spectrum method).

Examples of tackifier resins having an aromatic ring and substantially free of isoprene units, terpene skeletons and rosin skeletons include the above-mentioned aromatic petroleum resins, aliphatic / aromatic copolymer petroleum resins, styrene resins, etc. Examples include kumaron and inden resin. Among these, those having a softening point of 120 ° C. or higher (preferably 130 ° C. or higher, for example 135 ° C. or higher) can be adopted as the tackifier resin _THR2 . Among them, preferred tackifier resin _THR2 includes aromatic petroleum resin and styrene resin (for example, α-methylstyrene / styrene copolymer resin). Although not particularly limited, as the tackifier resin _{T HR2,} for the same reason as the tackifier resin _{T HR1,} hydroxyl value 30 mgKOH / g or less (preferably less than 5 mgKOH / g, for example less than 1 mgKOH / g) of those Can be preferably adopted. Therefore, as the tackifier resin _THR2 in the technique disclosed herein, those corresponding to the tackifier resin _THR1 can be preferably used. Similarly, as the tackifier resin _THR1 in the technique disclosed herein, those corresponding to the tackifier resin _THR2 can be preferably used. The technique disclosed herein can also be carried out in a mode in which the pressure-sensitive adhesive layer does not substantially contain the tackifier resin _THR2 .

Further, the total amount of tackifier resin T _H to unsaturated rubber 100 parts by weight (i.e., the total amount of softening point 100 ° C. or more tackifier resins), from the viewpoint of aggregation enhancing, suitable to be 10 parts by weight or more Yes, 20 parts by weight or more (for example, 25 parts by weight or more) is preferable. The content of the tackifier resin T _H to unsaturated rubber 100 parts by weight, for example, may be 60 parts by weight. From the viewpoint of tack and low temperature characteristics, the content of the tackifier resin T _H to unsaturated rubber 100 parts by weight, preferably 50 parts by weight or less, more preferably 45 parts by weight or less (for example, 40 parts by weight or less).

Ratio of tackifier resin T _H relative to the total amount of tackifying resin, from the viewpoint of achieving both good balance and cohesion and low temperature properties (e.g., low temperature initial adhesiveness) is suitably about 50 wt% or more, It is preferably 80% by weight or more (for example, 90% by weight or more). The art disclosed herein, substantially all of the tackifying resin (e.g., 95 to 100 wt%, more 99-100% by weight) may be preferably carried out in a manner which is tackifier resin _{T H.}

(Adhesive-imparting resin _TL )
The pressure-sensitive adhesive layer disclosed herein may contain a pressure-imparting resin _TL having a softening point of less than 100 ° C. The lower limit of the softening point of the tackifier resin _TL is not particularly limited. Those having a softening point of 40 ° C. or higher (typically 60 ° C. or higher) can be used. The hydroxyl value and structure of the tackifier resin _TL (for example, the presence or absence of an aromatic ring, the presence or absence of an isoprene unit, the presence or absence of a terpene skeleton, the presence or absence of a rosin skeleton, etc.) are not particularly limited. The various tackifier resins mentioned above (phenolic tackifier resins, terpene resins, modified terpene resins, rosin tackifier resins, petroleum resins, styrene resins, kumaron inden resins, ketone resins, etc.) are softened. Those having a point of less than 100 ° C. may be appropriately selected and used.

(Content of adhesive resin)
In the technique disclosed herein, the total amount (total content) of the tackifier resin is not particularly limited, and can be set so as to obtain desired performance according to the purpose and application. The total amount of the tackifier resin can be, for example, 1 part by weight or more with respect to 100 parts by weight of the unsaturated rubber, and may be 5 parts by weight or more, or 10 parts by weight or more. From the viewpoint of obtaining higher adhesive performance (for example, adhesive strength), the total amount of the tackifying resin with respect to 100 parts by weight of the unsaturated rubber may be 15 parts by weight or more, 20 parts by weight or more, or 25 parts by weight. It may be 3 parts or more, or 30 parts by weight or more. In some embodiments, the total amount of tackifier resin relative to 100 parts by weight of unsaturated rubber may be 40 parts by weight or more, or 55 parts by weight or more. Further, from the viewpoint of facilitating the realization of a pressure-sensitive adhesive exhibiting good tack and low-temperature performance (for example, initial adhesiveness at low temperature), the total amount of tackifier resin with respect to 100 parts by weight of unsaturated rubber is usually 120 parts by weight or less. Is appropriate, preferably 100 parts by weight or less, and more preferably 80 parts by weight or less. In some embodiments, the total amount of tackifier resin relative to 100 parts by weight of unsaturated rubber may be 60 parts by weight or less, 50 parts by weight or less, 45 parts by weight or less (eg 40 parts by weight or less). It may be.

<Anti-aging agent>
The pressure-sensitive adhesive disclosed herein may contain an anti-aging agent, if necessary. The use of anti-aging agent, increases the Mw _H maintenance of the pressure-sensitive adhesive comprising a combination of a tackifying resin and an unsaturated rubber can be improved long-term quality stability of the pressure-sensitive adhesive sheet (long life) .. As the anti-aging agent, one type may be used alone, two or more types may be used in combination, or three or more types may be used in combination.

(Radical scavenger)
In some embodiments, the anti-aging agent may include a radical scavenger (radical trapping agent). Examples of the radical scavenger include known radical scavengers that can be used in the field of unsaturated rubbers, such as phenolic antioxidants, hindered amines, and aromatic amines. The radical scavenger may be used alone or in combination of two or more.

Examples of radical scavengers that can be preferably used in the techniques disclosed herein include phenolic antioxidants. Non-limiting examples of phenolic antioxidants include monophenolic antioxidants such as 2,6-di-t-butyl-4-methylphenol and 2,6-di-t-butyl-4-ethylphenol. Agents; 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6) -T-butylphenol), bisphenol-based antioxidants such as 4,4'-thiobis (3-methyl-6-t-butylphenol); 1,3,5-trimethyl-2,4,6-tris (3,5) -Di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, 1,1,3- High molecular weight phenolic antioxidants such as tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane; and the like.

The phenolic antioxidant may be a hindered phenolic antioxidant. Non-limiting examples of the above hindered phenolic antioxidants include pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] and octadecyl-3- (3,3). 5-di-t-butyl-4-hydroxyphenyl) propionate, 4,6-bis (dodecylthiomethyl) -o-cresol, 4-[[4,6-bis (octylthio) -1,3,5-triazine) -2-yl] amino] -2,6-di-t-butylphenol, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate, bis (2,2) 6,6-Tetramethyl-4-piperidyl) Sevacate, a polycondensate of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol (dimethyl-1- (2) succinate −Hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate), and the like.

The amount of the radical scavenger (for example, a phenolic antioxidant) used can be, for example, 0.01 part by weight or more, and usually 0.05 part by weight or more, based on 100 parts by weight of the unsaturated rubber. Is appropriate, and may be 0.1 parts by weight or more (for example, 0.5 parts by weight or more). The increased amount of the radical scavenger, the higher the Mw _H retention tends to improve the quality stability of the adhesive sheet. From the viewpoint of suppressing an unfavorable effect on the adhesive performance (for example, a decrease in the cohesiveness of the adhesive before aging), the amount of the radical scavenger used with respect to 100 parts by weight of the unsaturated rubber is usually 10 parts by weight or less. Is appropriate, and is preferably 5 parts by weight or less (for example, 3 parts by weight or less).

(Sulfur-based antioxidant)
In some embodiments, the anti-aging agent may include a sulfur-based antioxidant. Sulfur-based antioxidant, to act continuously as peroxide decomposers convert the peroxide may occur in the pressure-sensitive adhesive to the degradation and / or stable compound, improvement of Mw _H retention (thus It can contribute to the improvement of quality stability of the adhesive sheet). In a pressure-sensitive adhesive containing an unsaturated rubber and a phenol-based tackifier resin (for example, a terpene phenol resin), it is particularly effective to use a sulfur-based antioxidant.

As the sulfur-based antioxidant, for example, a thioether-based antioxidant having a thioether structure in the molecule can be used. Non-limiting examples of sulfur-based antioxidants include 2,2-bis ({[3- (dodecylthio) propionyl] oxy} methyl) propandiyl-bis [3- (dodecylthio) propionate, bis [2-methyl]. -4- (3-n-dodecylthiopropionyloxy) -5-t-butylphenyl] sulfide, 3-dodecylsulfanyl propanoic acid = 2-t-butyl-4-[(5-t-butyl-4-hydroxy-) 2-Methylphenyl) sulfanyl] -5-methylphenyl, dilauryl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, di Examples thereof include stearyl-3,3'-thiodipropionate, pentaerythritol tetralaurylthiopropionate, and the like. One type of sulfur-based antioxidant may be used alone or in combination of two or more types. In some embodiments, an aromatic ring-free structure of a sulfur-based antioxidant (typically a thioether-based antioxidant) may be preferably employed. In addition, a thioether-based antioxidant having one or two or more (for example, three or four) "-CH _2- OC (O) -CH ₂ CH _2- S-CH _2- " structures in one molecule. Can be preferably adopted.

The number of thioether-based sulfur atoms contained in one molecule of the thioether-based antioxidant may be one or two or more. From the viewpoint of sustainability of the effect, a thioether-based antioxidant containing two or more (typically two or more and four or less) thioether-based sulfur atoms in one molecule is preferable. In some embodiments, a thioether-based antioxidant having a thioether equivalent (molecular weight per thioether sulfur atom) of 1000 or less (preferably 700 or less, more preferably 500 or less, eg 350 or less) can be used to improve adhesion performance. The Mw _H maintenance rate can be effectively improved while suppressing the influence. Further, from the viewpoint of sustainability of the effect, the thioether equivalent is preferably 150 or more, and more preferably 200 or more. The thioether equivalent can be calculated by dividing the molecular weight by the number of thioether sulfur atoms.

The molecular weight of the sulfur-based antioxidant is preferably 2000 or less, and preferably 1500 or less (for example, 1250 or less). The use of such sulfur-based antioxidant, can effectively improve the Mw _H maintenance rate while suppressing the influence on the adhesive properties (e.g., tack and cold initial adhesion). Further, from the viewpoint of sustainability of the effect, the molecular weight of the sulfur-based antioxidant is preferably 150 or more, preferably 200 or more, and more preferably 350 or more.

Regarding the amount of the sulfur-based antioxidant used with respect to the amount of the unsaturated rubber, for example, the number of moles of the thioether-based sulfur (S) contained in the sulfur-based antioxidant is 0.01 mmol or more per 100 g of the unsaturated rubber. Can be set as. Hereinafter, the number of moles of thioetheric sulfur per 100 g of unsaturated rubber is referred to as "S mole number" and may be expressed in units of mmol / 100 g. The number of S moles is usually preferably 0.05 mmol / 100 g or more, preferably 0.1 mmol / 100 g or more, may be 0.2 mmol / 100 g or more, and 0.5 mmol / 100 g or more ( For example, 0.8 mmol / 100 g or more) may be used. The increased S moles of sulfur antioxidants, the higher the Mw _H retention tends to improve the quality stability. The technique disclosed herein can also be preferably carried out in an embodiment in which the number of S moles is 1 mmol / 100 g or more (for example, 2 mmol / 100 g or more) or 4 mmol / 100 g or more (for example, 5 mmol / 100 g or more). Further, the number of S moles can be, for example, 100 mmol / 100 g or less, and is usually 50 mmol / 100 g or less from the viewpoint of suppressing an unfavorable effect on the adhesive performance (for example, deterioration of tack and low-temperature initial adhesiveness). It is appropriate to use 30 mmol / 100 g or less. The technique disclosed herein can also be preferably carried out in an embodiment in which the number of S moles is 20 mmol / 100 g or less, or 15 mmol / 100 g or less (for example, 10 mmol / 100 g or less).

The amount of the sulfur-based antioxidant used can be, for example, 0.01 part by weight or more with respect to 100 parts by weight of the unsaturated rubber, and usually 0.01 part by weight or more is appropriate, and 0.05 weight by weight. It may be 10 parts or more (for example, 0.1 parts by weight or more). The increased amount of sulfur-based antioxidant tends to improve Mw _H maintenance rate. Further, from the viewpoint of suppressing an unfavorable effect on the adhesive performance (for example, deterioration of tack and low-temperature initial adhesiveness), the amount of the sulfur-based antioxidant used per 100 parts by weight of the unsaturated rubber is usually 10 parts by weight or less. Is appropriate, preferably 7 parts by weight or less, and more preferably 5 parts by weight or less (for example, 3 parts by weight or less).

The amount of the sulfur-based antioxidant used can be, for example, 0.01 or more as the S molar ratio with respect to 100 parts by weight of the unsaturated rubber, and usually 0.05 or more is appropriate, and 0.1 or more (for example). It may be 0.5 or more). The increased S molar ratio of sulfur-based antioxidant, the higher the Mw _H retention tends to improve the quality stability. Further, from the viewpoint of suppressing an unfavorable effect on the adhesive performance (for example, deterioration of tack and low-temperature initial adhesiveness), the amount of the sulfur-based antioxidant used with respect to 100 parts by weight of the unsaturated rubber is usually set as the S molar ratio. , 15 or less is appropriate, 10 or less is preferable, and 7 or less (for example, 6 or less) is preferable. Reducing the S molar ratio can also be advantageous from the viewpoint of suppressing coloring (for example, yellowing) of the pressure-sensitive adhesive due to aging. Here, the S molar ratio is a value obtained by multiplying the number of parts by weight of the amount of the sulfur-based antioxidant used with respect to 100 parts by weight of the unsaturated rubber by the number of thioether-based sulfur contained in one molecule of the sulfur-based antioxidant. To say. For example, when 1 part by weight of a sulfur-based antioxidant is contained with respect to 100 parts by weight of unsaturated rubber, and the sulfur-based antioxidant contains two thioetheric sulfur in one molecule, the above-mentioned sulfur-based antioxidant in this composition. The S molar ratio of the antioxidant is calculated to be 2.

(Phosphorus antioxidant)
In some embodiments, the anti-aging agent may include a phosphorus-based antioxidant. Phosphorus-based antioxidant, to act as peroxide decomposers convert the peroxide may occur in the pressure-sensitive adhesive to degradation or stable compound, improvement of Mw _H retention (and hence the quality of the pressure-sensitive adhesive sheet stability It can contribute to the improvement of sex). Non-limiting examples of phosphorus-based antioxidants include tris (2,4-di-t-butylphenyl) phosphite, tris (nonylphenyl) phosphine, triphenylphosphine, distearylpentaerythritol diphosphite. , Etc. can be mentioned.

The amount of the phosphorus-based antioxidant used can be, for example, 0.05 parts by weight or more with respect to 100 parts by weight of the unsaturated rubber, and usually 0.1 parts by weight or more is appropriate, and 0.5 parts by weight. It may be 10 parts or more (for example, 1 part by weight or more). The increased amount of sulfur-based antioxidant tends to improve Mw _H maintenance rate. Further, from the viewpoint of suppressing an unfavorable effect on the adhesive performance (for example, deterioration of tack and low-temperature initial adhesiveness), the amount of the phosphorus-based antioxidant used with respect to 100 parts by weight of the unsaturated rubber is usually 15 parts by weight or less. Is appropriate, preferably 10 parts by weight or less, and more preferably 7 parts by weight or less (for example, 5 parts by weight or less).

In some embodiments, the anti-aging agent may be a combination of a sulfur-based antioxidant (eg, a thioether-based antioxidant) and a phosphorus-based antioxidant. According to this mode, it can be effectively improved the Mw _H maintenance rate by suppressing the undesirable effects on the adhesive properties. The reason is not particularly limited, but can be considered as follows, for example. That is, phosphorus-based antioxidants generally tend to react with peroxides more quickly than sulfur-based antioxidants. On the other hand, since phosphorus-based antioxidants are irreversibly consumed by the reaction with peroxides, the sustainability of the effect may be insufficient in a rigorous aging test of 80 ° C. for 4 weeks. By using two types of peroxide decomposition agents, a sulfur-based antioxidant and a phosphorus-based antioxidant, in combination, it is possible to continuously exert a good peroxide decomposition function while suppressing the influence on the adhesive properties. it can. Further, by using the sulfur-based antioxidant and the phosphorus-based antioxidant in combination, the amount of the sulfur-based antioxidant used can be reduced, which can contribute to the suppression of the coloration of the pressure-sensitive adhesive over time. More favorable results can be achieved by using a combination of a sulfur-based antioxidant, a phosphorus-based antioxidant and a phenol-based antioxidant.

Although not particularly limited, when used in combination with phosphorus-based antioxidant and a thioether-based antioxidant, the amount of the thioether-based antioxidant A _{S [S} molar ratio] to unsaturated rubber 100 parts by weight, the ratio amount _{a P} [parts] of the phosphorus-based antioxidant to unsaturated rubber 100 parts by weight, i.e. _a S / _{a P,} for example may be in the range of 0.1 to 10. Within this range, the effect of using the sulfur-based antioxidant and the phosphorus-based antioxidant in combination tends to be suitably exhibited. From the viewpoint of obtaining a better effect, in some embodiments, _AS / _AP may be 0.2 or more, or 0.5 or more. Further, _AS / _AP may be 5 or less, or 3 or less. Incidentally, A _P and A _S are respectively meant numeric portion when the amount expressed in parts by weight S molar ratio to unsaturated rubber 100 parts by weight, A _P and A values themselves dimensionless number of _S Suppose that

The radical scavengers disclosed herein may function as peroxide degradation agents in combination with or in combination with one or both of phosphorus and thioether oxidants, or in place of these antioxidants. It may contain an antioxidant. Examples of such other antioxidants include amine-based antioxidants (phenyl-α-naphthylamine, diphenylamine, etc.), benzimidazole-based antioxidants, and the like. The above-mentioned other antioxidants can be used alone, but are usually preferably used in combination with a radical scavenger (for example, a phenolic antioxidant).

(Content of anti-aging agent)
Although not particularly limited, the total amount of the antiaging agent contained in the pressure-sensitive adhesive disclosed herein can be, for example, approximately 20 parts by weight or less with respect to 100 parts by weight of unsaturated rubber, and is usually 15. It is appropriate that the amount is 10 parts by weight or less, and 10 parts by weight or less may be used. The technique disclosed herein is also suitably carried out in an embodiment in which the total amount of the antiaging agent used for 100 parts by weight of unsaturated rubber is 7 parts by weight or less (for example, 5 parts by weight or less, or 4 parts by weight or less). obtain. Further, the total amount of the antiaging agent can be, for example, 0.5 parts by weight or more with respect to 100 parts by weight of the unsaturated rubber, may be 1 part by weight or more, or may be 1.5 parts by weight or more. It may be 2 parts by weight or more.

<Isocyanate compound>
The pressure-sensitive adhesive layer disclosed herein may be formed from a pressure-sensitive adhesive composition containing an isocyanate-based compound in addition to an unsaturated rubber and a pressure-sensitive adhesive resin. According to such a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet having excellent long-term quality stability (for example, a decrease in cohesiveness is suppressed) can be realized. As the isocyanate compound, polyfunctional isocyanate (meaning a compound having an average of two or more isocyanate groups per molecule, including those having an isocyanurate structure) can be preferably used. As such a polyfunctional isocyanate, one or more selected from various isocyanate compounds (polyisocyanates) having two or more isocyanate groups in one molecule can be used. Examples of such polyfunctional isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates and the like.

Specific examples of aliphatic polyisocyanes include 1,2-ethylene diisocyanate; 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate, 1,4-tetramethylene diisocyanate and other tetramethylene diisocyanates; 1,2. -Hexamethylene diisocyanate such as 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,5-hexamethylene diisocyanate; Examples thereof include 2-methyl-1,5-pentanediisocyanate, 3-methyl-1,5-pentanediisocyanate and lysine diisocyanate.

Specific examples of alicyclic polyisocyanates include isophorone diisocyanates; 1,2-cyclohexyl diisocyanates, 1,3-cyclohexyl diisocyanates, cyclohexyl diisocyanates such as 1,4-cyclohexyl diisocyanates; 1,2-cyclopentyl diisocyanates, 1,3. Cyclopentyl diisocyanates such as −cyclopentyldiisocyanate; hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, and the like.

Specific examples of aromatic polyisocyanates include 2,4-tolylene diisocyanis, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 2,2'-diphenylmethane diisocyanate. , 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate , 4,4'-Diphenylpropane diisocyanate, m-phenylenediisocyanide, p-phenylenediisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate , Xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate and the like.

Preferred isocyanate compounds include polyfunctional isocyanates having an average of 3 or more isocyanate groups per molecule. Such trifunctional or higher functional isocyanates are bifunctional or trifunctional or higher functional isocyanate multimers (typically dimers or trimers), derivatives (eg, polyhydric alcohols and two or more molecules of polyfunctional isocyanates). It can be an addition reaction product), a polymer, or the like. For example, diphenylmethane diisocyanate dimer or trimeric, hexamethylene diisocyanate isocyanurate (isocyanurate structure trimeric adduct), reaction product of trimethylolpropane and tolylene diisocyanate, trimethylpropane and hexa. Examples thereof include reaction products with methylene diisocyanate, polyfunctional isocyanates such as polymethylene polyphenyl isocyanate, polyether polyisocyanate, and polyester polyisocyanate. Commercially available products of such polyfunctional isocyanates include the trade name "Duranate TPA-100" manufactured by Asahi Kasei Chemicals, the trade name "Coronate L", the same "Coronate HL", the same "Coronate HK", and the same "Coronate" manufactured by Tosoh Corporation. "HX", the same "Coronate 2096" and the like can be mentioned.

When an isocyanate compound is used, the amount used is not particularly limited, but is, for example, more than 0 parts by weight and 10 parts by weight or less (typically 0.01 to 10 parts by weight) with respect to 100 parts by weight of unsaturated rubber. be able to. The amount of the isocyanate compound used with respect to 100 parts by weight of the unsaturated rubber is preferably 0.1 part by weight or more (typically 0.3 parts by weight or more, for example 0.5 parts by weight or more), and 10 parts by weight or less. It is appropriate that the amount is 5 parts by weight or less (typically 3 parts by weight or less, for example, 1 part by weight or less). By using an isocyanate compound in such a range, an adhesive sheet having a particularly excellent performance balance can be realized.

<Other ingredients>
The pressure-sensitive adhesive layer disclosed herein may contain one or more rubber-like polymers other than unsaturated rubber, if necessary, as long as the effects of the present invention are not impaired. Such a rubber-like polymer can be various polymers such as rubber-based, acrylic-based, polyester-based, urethane-based, polyether-based, silicone-based, polyamide-based, and fluorine-based polymers known in the field of pressure-sensitive adhesives. The technique disclosed herein is an embodiment in which the pressure-sensitive adhesive layer substantially does not contain a rubber-like polymer other than unsaturated rubber (for example, the content per 100 parts by weight of unsaturated rubber is 0 to 1 part by weight). ) Can be preferably carried out.

The pressure-sensitive adhesive composition (which may also be a pressure-sensitive adhesive layer) disclosed herein can be a leveling agent, a cross-linking agent, a cross-linking aid, a plasticizer, a softening agent, a filler, a colorant (pigment, dye), if necessary. Etc.), antistatic agents, ultraviolet absorbers, light stabilizers, etc., which may contain various additives common in the field of adhesives. As for such various additives, conventionally known ones can be used by a conventional method.

The pressure-sensitive adhesive disclosed herein does not substantially contain liquid rubber such as polybutene (for example, the content per 100 parts by weight of unsaturated rubber is 1 part by weight or less, and may be 0 parts by weight. ) May be preferably carried out. Such an embodiment can be advantageous from the viewpoint of improving peel strength and cohesiveness.
In some embodiments, the pressure-sensitive adhesive composition may be composition that is substantially free of chelating compounds. Here, the chelate compound is, for example, a chelate compound of an oxide of an alkaline earth metal and a resin (alkylphenol resin, etc.) having a functional group (hydroxyl group, methylol group, etc.) to which the oxide can coordinate. Point to. The technique disclosed herein can be preferably carried out in a manner in which the pressure-sensitive adhesive composition does not contain such a chelate compound at all, or the content ratio of the chelate compound is 1% by weight or less. According to such an aspect, an adhesive sheet having more excellent adhesive strength can be realized.

In some embodiments, the pressure-sensitive adhesive is such that the total amount of the unsaturated rubber and the tackifier resin is 75% by weight of the total weight of the pressure-sensitive adhesive (ie, the weight of the pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive). It can be a composition that occupies the above. For example, the total amount of the unsaturated rubber and the tackifier resin is 80% by weight or more (for example, 85% by weight or more, or 90% by weight or more) and 99.8% by weight or less (typically) of the total weight of the pressure-sensitive adhesive. Specifically, for example, an embodiment of 99.5% by weight or less) can be preferably adopted.

<Adhesive composition>
The pressure-sensitive adhesive layer disclosed herein may be formed from a pressure-sensitive adhesive composition containing a component corresponding to the pressure-sensitive adhesive layer. The form of the pressure-sensitive adhesive composition is not particularly limited, and for example, the pressure-sensitive adhesive composition (solvent type) containing the pressure-sensitive adhesive (adhesive component) having the above-mentioned composition in an organic solvent, and the pressure-sensitive adhesive are dispersed in an aqueous solvent. It may be a pressure-sensitive adhesive composition in the form (water-dispersed type, typically an aqueous emulsion type), a hot-melt type pressure-sensitive adhesive composition, or the like. From the viewpoint of coatability, freedom of selection of the base material, and the like, a solvent-type or water-dispersible pressure-sensitive adhesive composition can be preferably adopted. A solvent-type pressure-sensitive adhesive composition is particularly preferable from the viewpoint of achieving higher pressure-sensitive adhesive performance.

The solvent-based pressure-sensitive adhesive composition is typically prepared in the form of a solution containing each of the above-mentioned components in an organic solvent. The organic solvent can be appropriately selected from known or commonly used organic solvents. For example, aromatic compounds such as toluene and xylene (typically aromatic hydrocarbons); acetate esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane, cyclohexane and methylcyclohexane. Classes; Alkanes halides such as 1,2-dichloroethane; Ketones such as methyl ethyl ketone and acetyl acetone; any one solvent selected from the above, or a mixed solvent of two or more kinds can be used. Although not particularly limited, it is appropriate to prepare the solvent-based pressure-sensitive adhesive composition to have a non-volatile content (NV) of 30% by weight or more (for example, 40% by weight or more), and 65% by weight or less (for example, 55% by weight). % Or less) is appropriate. If the NV is too low, the manufacturing cost tends to be high, and if the NV is too high, the handleability such as coatability may decrease.

As a method for obtaining a pressure-sensitive adhesive sheet from the pressure-sensitive adhesive composition, various conventionally known methods can be applied. For example, a method of forming a pressure-sensitive adhesive layer (direct method) by directly applying (typically applying) the pressure-sensitive adhesive composition to a base material and drying it can be preferably adopted. Further, the pressure-sensitive adhesive composition is applied to a surface having good peelability (for example, the surface of a release liner, the back surface of a support base material that has been released from the mold) and dried to form a pressure-sensitive adhesive layer on the surface. , The method of transferring the pressure-sensitive adhesive layer to the substrate (transfer method) may be adopted.
The pressure-sensitive adhesive composition can be applied using a known or conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater. From the viewpoint of promoting the cross-linking reaction and improving the production efficiency, it is preferable to dry the pressure-sensitive adhesive composition under heating. For example, a drying temperature of about 40 ° C. or higher (for example, 50 ° C. or higher, further 70 ° C. or higher) and about 150 ° C. or lower (typically 120 ° C. or lower, further 100 ° C. or lower) is preferably adopted. be able to. The drying time is not particularly limited, but may be about several tens of seconds to several minutes (for example, about 5 minutes or less, preferably about 30 seconds to 2 minutes). After that, an additional drying step may be provided if necessary. The pressure-sensitive adhesive layer is typically formed continuously, but may be formed in a regular or random pattern such as punctate or striped depending on the purpose and application.

(Thickness of adhesive layer)
Although not particularly limited, the thickness of the pressure-sensitive adhesive layer is appropriately about 4 μm or more (typically 20 μm or more, for example 30 μm or more), and about 150 μm or less (typically 120 μm or less, for example, for example. About 100 μm or less) is appropriate. In some embodiments, the thickness of the pressure-sensitive adhesive layer can be preferably 30 μm or greater, more preferably 40 μm or greater, and even more preferably 50 μm or greater (eg 60 μm or greater). A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having such a thickness can exhibit excellent pressure-sensitive adhesive performance (for example, peeling strength) in a configuration in which the pressure-sensitive adhesive layer contains an unsaturated rubber and a pressure-sensitive adhesive resin. Therefore, an adhesive sheet having both adhesive performance and quality stability (long life) can be provided. In the case of a double-sided pressure-sensitive adhesive sheet with a base material, it is preferable that both sides of the base material are provided with a pressure-sensitive adhesive layer having the above thickness. The thickness of each pressure-sensitive adhesive layer may be the same or different.

<Adhesive sheet>
(Base material)
When the technique disclosed herein is applied to a double-sided pressure-sensitive adhesive sheet with a base material or a single-sided pressure-sensitive adhesive sheet with a base material, the base material may be, for example, a polypropylene film, an ethylene-propylene copolymer film, a polyester film, or a polyvinyl chloride film. Plastic film such as; foam sheet made of foam such as polyurethane foam, polyethylene foam, polychloroprene foam; various fibrous substances (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, semi-acetate and the like Woven fabrics and non-woven fabrics (meaning to include papers such as Japanese paper and high-quality paper) by single or blended spinning of synthetic fibers, etc.); Metal foils such as aluminum foil and copper foil; etc. It can be appropriately selected and used according to the use of the adhesive sheet. The plastic film (typically a non-porous plastic film, which is a concept distinct from woven fabrics and non-woven fabrics) is either a non-stretched film or a stretched (uniaxially stretched or biaxially stretched) film. Can also be used. Further, the surface of the base material on which the pressure-sensitive adhesive layer is provided may be subjected to surface treatment such as application of a primer or corona discharge treatment.

In a preferred embodiment, a non-woven fabric (nonwoven fabric base material) is used as the base material. By using a non-woven fabric base material, low-temperature initial adhesiveness and cohesiveness (for example, performance to withstand without falling in a holding force test) tend to be improved. Examples of the non-woven fabric used for the base material include pulps such as wood pulp, non-woven fabric composed of natural fibers such as cotton and hemp; polyester fibers such as polyethylene terephthalate (PET) fibers, rayon, vinylon, acetate fibers, and polyvinyl. Use a non-woven fabric composed of chemical fibers (synthetic fibers) such as alcohol (PVA) fiber, polyamide fiber, polyolefin fiber, polyurethane fiber; and non-woven fabric composed of two or more kinds of fibers made of different materials in combination. Can be done. Among them, a non-woven fabric made of pulp or hemp (for example, hemp pulp), a non-woven fabric made of PET fiber, or the like is preferable from the viewpoint of impregnation property and repulsion resistance (curved surface followability) of the pressure-sensitive adhesive. The use of the non-woven fabric base material also contributes to the improvement of the flexibility and the hand-cutting property of the adhesive sheet.

As the non-woven fabric (nonwoven fabric base material), those having a basis weight of about 30 g / m ² or less (for example, 25 g / m ² or less, typically 20 g / m ² or less) can be preferably adopted. Such a non-woven fabric having a basis weight is suitable for producing an adhesive sheet that is lightweight and has excellent adhesive performance. From the viewpoint of repulsion resistance, a non-woven fabric having a basis weight of less than 18 g / m ² (for example, 16 g / m ² or less, typically 15 g / m ² or less) is preferable. From the viewpoint of improving the strength of the base material itself, the basis weight is preferably 10 g / m ² or more (for example, 12 g / m ² or more, typically 13 g / m ² or more).

The bulk density of the non-woven fabric base material (which can be calculated by dividing the basis weight by the thickness) is appropriately about 0.20 g / cm ³ or more, and 0.25 g / cm ³ or more (for example, 0.30 g / cm). ³ or more) is preferable, and about 0.50 g / cm ³ or less is suitable, and 0.40 g / cm ³ or less (for example, 0.35 g / cm ³ or less) is preferable. When the bulk density is within the above range, the base material itself has appropriate strength, and good pressure-sensitive adhesive impregnation property can be obtained. From the viewpoint of repulsion resistance, it is particularly preferable to use a non-woven fabric base material having a bulk density of about 0.25 to 0.40 g / cm ³ (for example, 0.30 to 0.35 g / cm ³ ).

The non-woven fabric base material contains resin components such as starch (for example, cationized starch), polyacrylamide, viscose, polyvinyl alcohol, urea formaldehyde resin, melamine formaldehyde resin, and polyamide polyamine epichlorohydrin in addition to the constituent fibers as described above. Can be. The resin component may function as a paper strength enhancer for the nonwoven fabric base material. The strength of the non-woven fabric base material can be adjusted by using such a resin component as needed. The nonwoven fabric substrate in the technique disclosed herein may optionally contain additives commonly used in the field of nonwoven fabric production, such as yield improvers, drainage agents, viscosity modifiers, dispersants and the like. ..

The thickness of the base material can be appropriately selected according to the purpose, but it is generally appropriate to set it to about 2 μm or more (typically 10 μm or more), and 500 μm or less (typically 200 μm or less). Is preferable. When a non-woven fabric is used as the base material, it is appropriate that the thickness of the non-woven fabric base material is about 150 μm or less. From the viewpoint of sufficiently impregnating the entire substrate with the pressure-sensitive adhesive, the thickness is preferably 100 μm or less (for example, 70 μm or less). Further, considering the handleability at the time of producing the pressure-sensitive adhesive sheet, the thickness is preferably 10 μm or more (for example, 25 μm or more). From the viewpoint of repulsion resistance, the thickness is preferably 30 μm or more (for example, 35 μm or more, typically 40 μm or more), and 60 μm or less (for example, 50 μm or less, typically 45 μm or less). Is preferable. The non-woven substrate disclosed herein has two or more of the above preferred ranges of basis weight, thickness and bulk density (for example, basis weight and thickness, more preferably all of basis weight, thickness and bulk density). It is preferable to satisfy. This makes it possible to realize an adhesive sheet in which a plurality of adhesive properties (for example, repulsion resistance, cohesiveness, peel strength, etc.) are highly balanced.

(Peeling liner)
As the release liner, a conventional release paper or the like can be used, and the release liner is not particularly limited. For example, a release liner having a release treatment layer on the surface of a substrate such as a plastic film or paper, or a release liner made of a low-adhesive material such as a fluoropolymer (polytetrafluoroethylene, etc.) or a polyolefin resin (polyethylene, polypropylene, etc.). Etc. can be used. The peeling treatment layer may be formed by surface-treating the base material with a peeling treatment agent such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide.

(Thickness of adhesive sheet)
The total thickness of the pressure-sensitive adhesive sheet disclosed herein is not particularly limited, and should be approximately 1000 μm or less (for example, 500 μm or less, typically 300 μm or less) from the viewpoint of thinning, weight reduction, resource saving, and the like. Is preferable. Further, from the viewpoint of ensuring good adhesive properties, it is appropriate to set the thickness to 50 μm or more (for example, 70 μm or more, typically 100 μm or more).

(Characteristic)
It is preferable that the pressure-sensitive adhesive sheet disclosed here does not drop the test piece in the holding power test of the pressure-sensitive adhesive sheet after the aging test. That is, it is preferable that the pressure-sensitive adhesive layer after the aging test maintains the above-mentioned level of cohesiveness showing the holding power. An adhesive sheet that satisfies the above characteristics is excellent in long-term quality stability. In the holding power test after the aging test, the pressure-sensitive adhesive sheet disclosed here has a deviation distance of 1 mm or less from the initial position, more preferably 0.5 mm or less.

Further, the pressure-sensitive adhesive sheet disclosed herein preferably exhibits a level of cohesiveness at which the test piece does not fall in the holding power test of the pressure-sensitive adhesive sheet before being subjected to the aging test. In the holding force test, the deviation distance from the initial position is more preferably 1 mm or less, and further preferably 0.5 mm or less.
The holding power test after the aging test and before the aging test is performed by the method described in Examples described later. When a holding force test is carried out using a single-sided adhesive sheet as a test piece, it is not necessary to attach a PET film to the first adhesive surface of the test piece.

<Use>
The adhesive sheet disclosed herein is a joint between members in various OA equipment (for example, PC), home appliances (for example, rice cooker, refrigerator), automobiles, building materials (for example, housing building materials), etc. (for example, various types in such products). It is useful for fixing parts and nameplates). The adhesive sheet disclosed here takes advantage of its excellent long-term quality stability, and for example, a decorative sheet used for decorating the inner wall of a building is fixed to the attachment position (inner wall) of the decorative sheet. It can be preferably used in applications.

Matters disclosed by this specification include:
(1) An adhesive sheet containing an adhesive layer.
The pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive containing an unsaturated rubber and a pressure-sensitive adhesive resin.
The pressure-sensitive adhesive has a weight average molecular weight Mw _H calculated for a region having a molecular weight of 10,000 g / mol or more from a molecular weight distribution curve based on GPC measurement, and has a maintenance rate of 70% or more in an aging test at 80 ° C. for 4 weeks (for example, An adhesive sheet that is 70% to 100%).
(2) The pressure-sensitive adhesive sheet according to (1) above, wherein the content of the unsaturated rubber is approximately 30% by weight or more of the pressure-sensitive adhesive.
(3) The pressure-sensitive adhesive sheet according to (1) or (2) above, wherein the content of the pressure-sensitive adhesive resin is about 10 parts by weight or more and about 120 parts by weight or less with respect to 100 parts by weight of the unsaturated rubber.
(4) The tackifier resin is at least selected from the group consisting of phenol-based tackifier resins, terpene resins, modified terpene resins, rosin-based tackifier resins, petroleum resins, styrene resins, Kumaron-Inden resins and ketone resins. The adhesive sheet according to any one of (1) to (3) above, which comprises one type.
(5) The tackifier resin contains a phenolic tackifier resin, and the content of the phenolic tackifier resin is about 5 parts by weight or more and about 60 parts by weight or less with respect to 100 parts by weight of the unsaturated rubber. The adhesive sheet according to any one of (1) to (4) above.
(6) The tackifier resin according to any one of (1) to (5) above, wherein the tackifier resin contains a phenolic tackifier resin, and the phenolic tackifier resin contains a terpene phenol resin having a hydroxyl value of 20 mgKOH / g or more. Adhesive sheet.
(7) The tackifier resin according to any one of (1) to (6) above, wherein the tackifier resin contains a phenolic tackifier resin, and the phenolic tackifier resin contains a terpene phenol resin having a hydroxyl value of 80 mgKOH / g or more. Adhesive sheet.
(8) The pressure-sensitive adhesive sheet according to any one of (1) to (7) above, wherein the softening point of the pressure-sensitive adhesive resin is 40 ° C. or higher (for example, 60 ° C. or higher).

(9) The pressure-sensitive adhesive sheet according to any one of (1) to (8) above, wherein the pressure-sensitive adhesive contains an anti-aging agent, and the anti-aging agent contains a radical scavenger and a sulfur-based antioxidant.
(10) The pressure-sensitive adhesive sheet according to any one of (1) to (9) above, wherein the pressure-sensitive adhesive contains an anti-aging agent, and the anti-aging agent contains a phosphorus-based antioxidant.
(11) The pressure-sensitive adhesive contains an anti-aging agent, and the anti-aging agent contains a thioether-based antioxidant as a sulfur-based antioxidant and a phosphorus-based antioxidant.
Ratio above unsaturated use of thioether antioxidants for rubber 100 parts by weight A _{S [S} molar ratio], the amount A _{P [parts]} of the phosphorus-based antioxidant relative to the unsaturated rubber 100 parts by weight ( a _S / _{a P)} is 0.1 to 10, the pressure-sensitive adhesive sheet according to any one of the above (1) to (10).
(12) The adhesive sheet according to any one of (8) to (11) above, wherein the total amount of the anti-aging agent is 1.5 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the unsaturated rubber. ..
(13) The pressure-sensitive adhesive sheet according to any one of (1) to (12) above, wherein the pressure-sensitive adhesive has a content of a phenol-based pressure-sensitive adhesive resin of 30 parts by weight or less with respect to 100 parts by weight of the unsaturated rubber.
(14) The pressure-sensitive adhesive sheet according to any one of (1) to (13) above, wherein the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer contains an isocyanate compound.
(15) In the pressure-sensitive adhesive, the total amount of the unsaturated rubber and the pressure-sensitive adhesive resin is approximately 85% by weight or more and 99.8% by weight or less of the total weight of the pressure-sensitive adhesive. The adhesive sheet according to any one of 14).

(16) The pressure-sensitive adhesive sheet according to any one of (1) to (15) above, wherein the unsaturated rubber is a homopolymer or a copolymer of a conjugated diene compound.
(17) The pressure-sensitive adhesive sheet according to any one of (1) to (16) above, wherein the unsaturated rubber is a homopolymer or copolymer of isoprene.
(18) Any of the above (1) to (17), wherein the unsaturated rubber has a monomer composition containing a conjugated diene compound, and the ratio of the conjugated diene compound to the monomer composition is approximately 70% by weight or more. Adhesive sheet described in.
(19) The pressure-sensitive adhesive sheet according to any one of (1) to (18) above, wherein the unsaturated rubber contains a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound.
(20) The pressure-sensitive adhesive sheet according to (19) above, wherein the ratio of the diblock body of the block copolymer is approximately 60% by weight or more.
(21) The pressure-sensitive adhesive sheet according to any one of (1) to (20) above, wherein the thickness of the pressure-sensitive adhesive layer is about 30 μm or more.
(22) It is configured as a double-sided adhesive pressure-sensitive adhesive sheet comprising a base material and a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer as the pressure-sensitive adhesive layers supported on both sides of the base material, respectively. The adhesive sheet according to any one of (1) to (21) above.

(23) An adhesive sheet containing an adhesive layer.
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer contains an unsaturated rubber and a pressure-sensitive adhesive resin having a softening point of 60 ° C. or higher.
The unsaturated rubber contains a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound, and the block copolymer contains 70% by weight or more of the conjugated diene compound in the monomer composition and the diene compound. The block body ratio is about 60% by weight or more,
The content of the unsaturated rubber is about 30% by weight or more of the adhesive.
The tackifier resin contains at least one selected from the group consisting of a phenolic tackifier resin, a terpene resin, a modified terpene resin, a rosin-based tackifier resin, a petroleum resin, and a Kumaron-Inden resin.
The total amount of the tackifier resin is about 10 parts by weight or more and about 120 parts by weight or less with respect to 100 parts by weight of the unsaturated rubber.
The pressure-sensitive adhesive has a weight average molecular weight Mw _H calculated for a region having a molecular weight of 10,000 g / mol or more from a molecular weight distribution curve based on GPC measurement, and has a maintenance rate of 70% or more (for example, in an aging test at 80 ° C. for 4 weeks). An adhesive sheet that is 70% to 100%).
(24) The pressure-sensitive adhesive sheet according to (23) above, wherein the pressure-sensitive adhesive contains an anti-aging agent, and the anti-aging agent contains a radical scavenger and a sulfur-based antioxidant.

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

<Making a double-sided adhesive sheet>
(Example 1)
100 parts of styrene isocyanate block copolymer (manufactured by Nippon Zeon, product name "Quintac 3520", styrene content 15%, diblock ratio 78%), 40 parts of terpene phenol resin, and 30 parts of terpene resin. Parts, 0.75 parts of isocyanate compound (Product name of Toso Co., Ltd., product name "Coronate L"), and product name "EUNOX AO-565" manufactured by Eutec Chemical Co., Ltd. as a radical trapping agent. 4- [[4,6-bis (octylthio) -1,3,5-triazine-2-yl] amino] -2,6-di-t-butylphenol) and a phosphorus-based antioxidant (BASF) Product name "IRGAFOS 168", Tris (2,4-di-t-butylphenyl) phosphite) 2 parts, and thioether-based antioxidant (Product name "Adecastab AO-503" manufactured by ADEKA, ditridecyl- Two parts of 3,3'-thiodipropionate) and toluene as a solvent were stirred and mixed to prepare a pressure-sensitive adhesive composition having an NV of 50%.
Here, as the terpene phenol resin, the product name "YS Polystar S145" (softening point 145 ° C., hydroxyl value 100 mgKOH / g) manufactured by Yasuhara Chemical Co., Ltd. and the product name "YS Polystar T145" (softening point 145 ° C.) manufactured by the same company Two types with a hydroxyl value of 60 mgKOH / g) were used at a weight ratio of 1: 1 so that the total of them was 40 parts. As the terpene resin, a product name “YS Resin PX1150N” manufactured by Yasuhara Chemical Co., Ltd. (softening point 115 ° C., hydroxyl value less than 1 mgKOH / g) was used.

The pressure-sensitive adhesive composition obtained above is applied to a release liner, dried at 120 ° C. for 3 minutes, and bonded to a 12 μm-thick PET film (manufactured by Toray Industries, Inc., trade name “Lumilar S10”) to a thickness. A 64 μm pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) was formed. Next, an adhesive layer (second adhesive layer) having a thickness of 64 μm was formed on the second surface (the surface opposite to the first surface) of the PET film in the same manner as the first surface. In this way, the double-sided adhesive sheet according to this example was produced. As a release liner, a release paper having a thickness of about 89 μm (Oji F-Tex Co., Ltd.) in which one side (the surface on the adhesive layer side) is peeled off with a silicone-based release agent on both the first side and the second side. Made of high-quality paper, polylami paper with polyethylene laminated on one side, product name "Separate 75EPS (M) Cream Kai") was used.

(Example 2)
ADEKA's product name "ADEKA Stab AO-412S" (2,2-bis ({[3- (dodecylthio) propionyl] oxy} methyl) propandiyl-bis [3- (dodecylthio) propionate) thioether-based antioxidant) A double-sided pressure-sensitive adhesive sheet according to this example was produced in the same manner as in Example 1 except that it was changed to two parts.

(Example 3)
The double-sided pressure-sensitive adhesive sheet according to Example 3 was produced in the same manner as in Example 1 except that the amounts of each terpene phenol resin and terpene resin used were changed to those shown in Table 1.

(Example 4)
A double-sided pressure-sensitive adhesive sheet according to Example 4 was prepared in the same manner as in Example 1 except that a thioether-based antioxidant was not used.

<Aging test>
The pressure-sensitive adhesive sheet according to each example was cut into a rectangular shape with a length of 30 cm and a width of 20 cm together with the release liner covering both pressure-sensitive adhesive surfaces to prepare a sample for an aging test. The sample was stored for 4 weeks in a dryer with an air atmosphere maintained at 80 ° C. The samples were hung in the dryer and stored so as not to overlap each other.

<Mw _H maintenance rate>
For the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet before and after the aging test, GPC measurement was performed by the method described above, and pre-aging Mw _H and post-aging using the analysis software attached to the GPC measuring device. Mw _H was calculated. Further, after the following equation :( aging Mw _H / aging before Mw _H) × 100; a calculated Mw _H maintenance rate (%). The results are shown in Table 1.

<Holding power test>
For each of the adhesive sheets before and after the aging test, a PET film having a thickness of 25 μm (manufactured by Toray Industries, Inc., trade name “Lumilar S10”) was formed on the first adhesive surface (adhesive surface of the first adhesive layer) of the adhesive sheet. ) Was bonded together and cut into a strip having a width of 10 mm to prepare a test piece. The second adhesive surface (adhesive surface of the second adhesive layer) of the test piece is exposed, and the test piece is used as a bakelite plate (phenol resin plate) as an adherend in an environment of 23 ° C. and 50% RH. A 2 kg roller was reciprocated once in a pasting area having a width of 10 mm and a length of 20 mm for crimping. After the test piece attached to the test piece in this way was left in the same environment for 30 minutes, the test piece was hung down so that the length direction of the test piece was the vertical direction, and the free end of the test piece was hung down. Was subjected to a load of 500 g and left in an environment of 40 ° C. for 30 minutes in a state where the load was applied according to JIS Z0237. For the test piece after being left to stand, the distance (deviation distance) deviated from the initial sticking position was measured. The measurement was performed using three test pieces for each adhesive sheet (that is, n = 3), and the arithmetic mean value of the deviation distance related to those test pieces is shown in the “holding power” column of Table 1. In addition, when even one test piece fell, it was described as "falling".

As shown in Table 1, the pressure-sensitive adhesive sheet of Example 1 to 3 Mw _H maintenance rate is 70% or more, after a severe aging test of 4 weeks at 80 ° C. Also, good level without falling in the holding power test Cohesiveness was maintained. On the other hand, the adhesive sheet of Example 4 having an Mw _H retention rate of less than 70% had the same cohesiveness as Examples 1 and 2 at the beginning (before the aging test), but the cohesiveness was improved by the aging test. It decreased significantly and could not withstand the retention test after the aging test. Specifically, all three test pieces fell before the lapse of 30 minutes. In the pressure-sensitive adhesive sheet according to Example 1, the pressure-sensitive adhesive was slightly colored after the aging test.

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

1,2,3 Adhesive sheet 11 First adhesive layer 12 Second adhesive layer 15 Base material 21,22 Peeling liner

Claims (8)

An adhesive sheet containing an adhesive layer,
The pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive containing an unsaturated rubber and a pressure-sensitive adhesive resin.
The unsaturated rubber is a styrene isoprene block copolymer, the diblock ratio of the styrene isoprene block copolymer is 60% by weight or more, and the content of the unsaturated rubber is 50% by weight or more of the pressure-sensitive adhesive. And
The tackifier resin contains a phenolic tackifier resin, and the content of the phenolic tackifier resin is 5 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the unsaturated rubber.
The pressure-sensitive adhesive contains a phenol-based antioxidant, a sulfur-based antioxidant, and a phosphorus-based antioxidant as antiaging agents.
The pressure-sensitive adhesive maintains a weight average molecular weight Mw _H calculated from a molecular weight distribution curve based on gel permeation chromatograph measurement for a region having a polystyrene-equivalent molecular weight of 10,000 g / mol or more in an aging test at 80 ° C. for 4 weeks. Adhesive sheet with a rate of 70% or more. The pressure-sensitive adhesive sheet according to claim 1, wherein the content of the tackifier resin is 10 parts by weight or more and 120 parts by weight or less with respect to 100 parts by weight of the unsaturated rubber. The pressure-sensitive adhesive sheet according to claim 1 or 2 , wherein the pressure-sensitive adhesive has a softening point of 40 ° C. or higher. The tackifier resin contains a phenolic tackifier resin and contains
The pressure-sensitive adhesive sheet according to any one of claims 1 to 3 , wherein the phenol-based tackifier resin contains a terpene phenol resin having a hydroxyl value of 20 mgKOH / g or more. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4 , wherein the content of the phenolic pressure-sensitive adhesive resin with respect to 100 parts by weight of the unsaturated rubber is 30 parts by weight or less. The proportion of the conjugated diene compound accounts for motor Nomar composition of unsaturated rubber is 70 wt% or more, the pressure-sensitive adhesive sheet according to any one of claims 1 to 5. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6 , wherein the pressure-sensitive adhesive layer has a thickness of 30 μm or more. 1. A double-sided adhesive adhesive sheet comprising a base material and a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer as the pressure-sensitive adhesive layers supported on both sides of the base material, respectively. The adhesive sheet according to any one of 7 to 7 .

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