JP6006032B2 - Adhesive composition and adhesive sheet - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition comprising a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound (for example, a styrenic block copolymer) as a base polymer. Moreover, this invention relates to the adhesive sheet provided with the adhesive which uses this copolymer as a base polymer.

  In general, a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive; the same shall apply hereinafter) is in the form of a soft solid (viscoelastic body) in a temperature range near room temperature and has a property of easily adhering to an adherend by pressure. Taking advantage of such properties, pressure-sensitive adhesives are widely used in various industrial fields such as home appliances, automobiles, and office automation equipment as a bonding means with good workability and high adhesion reliability. A typical composition of the pressure-sensitive adhesive includes a composition containing a base polymer and a tackifying resin. As the base polymer, a polymer exhibiting rubber elasticity at room temperature can be preferably employed. For example, Patent Documents 1 to 3 describe an adhesive containing a styrene block copolymer such as a styrene isoprene styrene block copolymer (SIS) or a styrene butadiene styrene block copolymer (SBS).

JP 2001-123140 A JP 2001-342441 A Japanese Patent Laid-Open No. 10-287858

  By the way, due to the nature of the pressure-sensitive adhesive that can be easily crimped to the adherend as described above, the bonded portion with the pressure-sensitive adhesive is resistant to stress continuously applied to the bonded portion (a good bonded state against the stress). Tends to be low). For example, as shown in FIG. 2, a first surface 32A at one end 32 of a blade (resin blade) 30 made of a thick plastic film is fixed (bonded) to the surface of a plastic molded body 36 with a double-sided pressure-sensitive adhesive sheet 1 and molded. The roll 38 is rotated while the first surface 34A of the other end 34 of the blade 30 is pressed by the elastic force of the blade 30 against the surface of the rotating roll 38 disposed in the vicinity of the body 36, thereby adhering the surface of the roll. In the aspect of scraping off, continuous stress is applied to the joint portion by the double-sided pressure-sensitive adhesive sheet 1 due to the frictional force accompanying the rotation of the roll 38 and the elastic force of the blade 30. Even in such a usage mode, it is useful if a pressure-sensitive adhesive sheet is provided in which the joint is difficult to peel off.

  Therefore, an object of the present invention is to provide a pressure-sensitive adhesive composition that can realize a pressure-sensitive adhesive sheet having high resistance to continuous stress. Another related object is to provide an adhesive sheet that is highly resistant to continuous stress.

  The pressure-sensitive adhesive composition disclosed herein contains a base polymer and a tackifying resin. The base polymer is a block copolymer of a monovinyl substituted aromatic compound and a conjugated diene compound. The tackifying resin contains a low softening point resin having a softening point of less than 120 ° C and a high softening point resin having a softening point of 120 ° C or higher. And the said high softening point resin contains a terpene phenol resin. According to the pressure-sensitive adhesive composition having such a composition, a pressure-sensitive adhesive sheet excellent in resistance to continuously applied stress (for example, performance of maintaining bonding against the bending force of a thick plastic film) can be realized.

  According to this specification, the adhesive sheet which has an adhesive layer is also provided. The pressure-sensitive adhesive layer contains a base polymer and a tackifying resin. The base polymer is a block copolymer of a monovinyl substituted aromatic compound and a conjugated diene compound. The tackifying resin contains a low softening point resin having a softening point of less than 120 ° C and a high softening point resin having a softening point of 120 ° C or higher. And the said high softening point resin contains a terpene phenol resin. The pressure-sensitive adhesive sheet provided with such a pressure-sensitive adhesive layer can be excellent in resistance to continuously applied stress (for example, performance of maintaining bonding against the bending force of a thick plastic film).

It is typical sectional drawing which shows the structure of the adhesive sheet (double-sided adhesive sheet with a base material) which concerns on one Embodiment. It is typical sectional drawing which illustrates the usage condition of an adhesive sheet. It is explanatory drawing which shows the evaluation method of repulsion resistance. It is explanatory drawing which shows the evaluation method of a constant load peeling characteristic. It is a characteristic view which shows the repulsion resistance evaluation result of the double-sided adhesive sheet which concerns on a1-a6. It is a characteristic view which shows the repulsion resistance evaluation result of the double-sided adhesive sheet which concerns on c1-c5. It is a characteristic view which shows the repulsion resistance evaluation result of the double-sided adhesive sheet which concerns on e1-e7. It is typical sectional drawing which shows the structure of the adhesive sheet (base-material-less double-sided adhesive sheet) which concerns on other embodiment. It is typical sectional drawing which shows the structure of the adhesive sheet (single-sided adhesive sheet with a base material) which concerns on other embodiment.

Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.
In the following drawings, members / parts having the same action are described with the same reference numerals, and redundant descriptions may be omitted or simplified. In addition, the embodiment described in the drawings is schematically illustrated for clearly explaining the present invention, and does not accurately represent the size and scale of the pressure-sensitive adhesive sheet of the present invention actually provided as a product.

In this specification, the “pressure-sensitive adhesive” refers to a material that exhibits a soft solid (viscoelastic body) state in a temperature range near room temperature and has a property of easily adhering to an adherend by pressure as described above. . The adhesive here is generally defined as “CA Dahlquist,“ Adhesion: Fundamental and Practice ”, McLaren & Sons, (1966) P. 143”, and generally has a complex tensile modulus E ^* (1 Hz). <10 < ⁷ > dyne / cm < ² > material (typically a material having the above properties at 25 [deg.] C.). The “base polymer” of the pressure-sensitive adhesive is the main component (that is, 50% by mass of the rubber-like polymer) of the rubber-like polymer (polymer exhibiting rubber elasticity in the temperature range near room temperature) contained in the pressure-sensitive adhesive. Component which occupies the above).

  In this specification, “a 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 mass; the same shall apply hereinafter). A polymer having at least one segment (hereinafter also referred to as “A segment”) and at least one segment having a conjugated diene compound as a main monomer (hereinafter also referred to as “B segment”). In general, 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 triblock copolymer (ABA structure triblock) having A segments (hard segments) at both ends of a B segment (soft segment), one A Examples thereof include a diblock structure copolymer (A-B structure diblock body) composed of a segment and one B segment.

  In this specification, the “styrene block copolymer” means a polymer having at least one styrene block. The styrene block refers to a segment having styrene as a main monomer. A segment consisting essentially of styrene is a typical example of a styrene block as used herein. The “styrene isoprene block copolymer” refers to a polymer having at least one styrene block and at least one isoprene block (a segment having isoprene as a main monomer). Typical examples of styrene isoprene block copolymers are triblock copolymer (triblock body) having styrene blocks (hard segment) at both ends of isoprene block (soft segment), one isoprene block and one styrene. Examples thereof include a diblock 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 (a segment containing butadiene as a main monomer).

In this specification, the “styrene content” of the styrenic block copolymer refers to the mass ratio of the styrene component to the total mass of the block copolymer. The styrene content can be measured by NMR (nuclear ceramic resonance spectrum method).
Further, the ratio of the diblock body in the styrene block copolymer (hereinafter sometimes referred to as “diblock body ratio” or “diblock ratio”) is determined by the following method. That is, a styrene block copolymer is dissolved in tetrahydrofuran (THF), and GS5000H and G4000H liquid chromatograph columns manufactured by Tosoh Corporation are connected in two stages in total, for a total of four stages, and THF is used as the mobile phase. Then, perform high performance liquid chromatography under the conditions of a temperature of 40 ° C. and a flow rate of 1 ml / min, measure the peak area corresponding to the diblock body from the obtained chart, and calculate the 100% of the peak area relative to the total peak area. It is obtained by calculating.

<Structural example of adhesive sheet>
The pressure-sensitive adhesive sheet disclosed herein (which may be in a long form such as a tape) 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 plastic film 15 as a base material, and a first pressure-sensitive adhesive layer 11 and a second pressure-sensitive adhesive layer 12 that are respectively supported on both surfaces of the base material 15. More specifically, the first pressure-sensitive adhesive layer 11 and the second pressure-sensitive adhesive layer 12 are provided on the first surface 15A and the second surface 15B (both non-peelable) of the base material 15, respectively. As shown in FIG. 1, the double-sided pressure-sensitive adhesive sheet 1 before use (before being attached to an adherend) is wound in a spiral shape with the front surface 21A and the back surface 21B overlapped with a release liner 21 which is a release surface. It can be in the form of In the double-sided pressure-sensitive adhesive sheet 1 in this form, the surface of the second pressure-sensitive adhesive layer 12 (second pressure-sensitive adhesive surface 12A) is peeled off by the front surface 21A of the release liner 21, and the surface of the first pressure-sensitive adhesive layer 11 (first pressure-sensitive adhesive surface 11A) is peeled off. The liner 21 is protected by the back surface 21B. Alternatively, the first adhesive surface 11A and the second adhesive surface 12A may be protected by two independent release liners.

  The technique disclosed here is preferably applied to a double-sided pressure-sensitive adhesive sheet with a base material as shown in FIG. 1, and a double-sided pressure-sensitive adhesive sheet 2 having no base material (that is, having no base material) as shown in FIG. 8. It can also be applied to. For example, as shown in FIG. 8, the double-sided pressure-sensitive adhesive sheet 2 before use is such that the first pressure-sensitive adhesive surface 11A and the second pressure-sensitive adhesive surface 11B of the substrate-less pressure-sensitive adhesive layer 11 are at least the surface (front surface) on the pressure-sensitive adhesive layer side. May be protected by release liners 21 and 22 that are release surfaces. Alternatively, the release liner 22 is omitted, and the release liner 21 having both sides of the release surface is used, and this and the adhesive layer 11 are overlapped and wound into a spiral shape, whereby the second adhesive surface 11B is released into the release liner. 21 may be in contact with the back surface of 21 and protected.

  As shown in FIG. 9, the technology disclosed herein is also a single-sided adhesive type base including a base material 15 and a pressure-sensitive adhesive layer 11 supported on the first surface (non-peeling surface) 15 </ b> A of the base material. It can be applied to the pressure-sensitive adhesive sheet 3 with material. For example, as shown in FIG. 9, the pressure-sensitive adhesive sheet 3 before use has a release liner in which the surface (adhesive surface) 11 </ b> A of the pressure-sensitive adhesive layer 11 is at least the surface (front surface) on the pressure-sensitive adhesive layer side. 21 may be the protected form. Alternatively, the release liner 21 is omitted, and the first adhesive surface 11A is the second of the substrate 15 by winding the adhesive sheet 3 with the substrate using the substrate 15 having the second surface 15B as the release surface. It may be in a form protected against the surface 15B.

  Hereinafter, although the case where the technique disclosed here is applied to the double-sided pressure-sensitive adhesive sheet with a substrate or the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet is described as a main example, the application target of the technique is not intended to be limited.

<Base polymer>
The pressure-sensitive adhesive in the technology disclosed herein (which can also be grasped as the solid content of the pressure-sensitive adhesive composition or the constituent material of the pressure-sensitive adhesive layer) is a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound as a base polymer. Contains a polymer. 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, vinyl toluene, vinyl xylene and the like. Specific examples of the conjugated diene compound include 1,3-butadiene and isoprene. Such a block copolymer can be used for a base polymer individually by 1 type or in combination of 2 or more types.

  The A segment (hard segment) in the block copolymer has a copolymerization ratio of 70% by mass or more (more preferably 90% by mass or more) of the monovinyl-substituted aromatic compound (two or more types can be used in combination). It may be substantially 100% by mass). The B segment (soft segment) in the block copolymer has a copolymerization ratio of the conjugated diene compound (two or more can be used in combination) of 70% by mass or more (more preferably 90% by mass or more). It may be 100% by mass). 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, and the like. In the triblock body and the radial body, it is preferable that an A segment (for example, a 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 cross-linked structure and improving the cohesiveness of the pressure-sensitive adhesive. The block copolymer used in the technology disclosed herein is a diblock ratio from the viewpoint of adhesive strength (peel strength) and repulsion resistance (especially repulsion resistance under wet heat conditions) to the adherend. Is preferably 30% by mass or more (more preferably 40% by mass or more, further preferably 50% by mass or more, particularly preferably 60% by mass or more, typically 65% by mass or more, for example 70% by mass or more). be able to. Further, from the viewpoint of resistance to constant load peeling (constant load peeling characteristics), a diblock body ratio of 90% by mass or less (more preferably 85% by mass or less, for example, 80% by mass or less) can be preferably used. In one embodiment of the technology disclosed herein, the block copolymer has a diblock ratio of 30 to 80% by mass (more preferably 40 to 80% by mass, still more preferably 50 to 80% by mass, for example 50 to 70% by mass) can be preferably employed. In another embodiment (for example, an embodiment containing terpene phenol resins A and B having different hydroxyl values as tackifying resins as described later), the block copolymer has a diblock body ratio of 30 to 90% by mass ( Typically, 40 to 90% by mass, preferably 50 to 90% by mass, for example 60 to 85% by mass) can be preferably employed.

<Styrenic block copolymer>
In a preferred embodiment of the technology disclosed herein, the base polymer is a styrenic block copolymer. For example, it can be preferably implemented in an embodiment in which the base polymer contains at least one of a styrene isoprene block copolymer and a styrene butadiene block copolymer. Of the styrene block copolymer contained in the pressure-sensitive adhesive, the proportion of the styrene isoprene block copolymer is 70% by mass or more, the proportion of the styrene butadiene block copolymer is 70% by mass or more, or styrene. The total ratio of the isoprene block copolymer and the styrene butadiene block copolymer is preferably 70% by mass or more. In a preferred embodiment, substantially all (for example, 95 to 100% by mass) of the styrenic block copolymer is a styrene isoprene block copolymer. In another preferred embodiment, substantially all (for example, 95 to 100% by mass) of the styrenic block copolymer is a styrene butadiene block copolymer. According to these compositions, a pressure-sensitive adhesive sheet having excellent resistance to continuously applied stress and having a good balance with other pressure-sensitive adhesive properties can be suitably realized.

  The styrenic block copolymer may be in the form of a diblock body, a triblock body, a radial body, a mixture thereof, and the like. In a triblock body and a radial body, it is preferable that the styrene block is arranged at the terminal of the polymer chain. This is because the styrene blocks arranged at the end of the polymer chain are likely to gather to form a styrene domain, thereby forming a pseudo cross-linked structure and improving the cohesiveness of the pressure-sensitive adhesive. The styrenic block copolymer used in the technology disclosed herein is a diblock from the viewpoint of adhesive strength (peeling strength) to an adherend and repulsion resistance (especially repulsion resistance under wet heat conditions). A body ratio of 30% by mass or more (more preferably 40% by mass or more, further preferably 50% by mass or more, particularly preferably 60% by mass or more, typically 65% by mass or more, for example, 70% by mass or more). It can be preferably used. Further, from the viewpoint of resistance to constant load peeling (constant load peeling characteristics), a diblock body ratio of 90% by mass or less (more preferably 85% by mass or less, for example, 80% by mass or less) can be preferably used. In one aspect of the technology disclosed herein, the styrenic block copolymer has a diblock body ratio of 30 to 80% by mass (more preferably 40 to 80% by mass, still more preferably 50 to 80% by mass, for example, (50-70 mass%) can be preferably employed. In another embodiment (for example, an embodiment containing terpene phenol resins A and B having different hydroxyl values as a tackifier resin as described later), the diblock body ratio is 30 to 90 mass as the styrenic block copolymer. % (Typically 40 to 90% by mass, preferably 50 to 90% by mass, for example 60 to 85% by mass) can be preferably used.

  The styrene content of the styrenic block copolymer may be, for example, 5 to 40% by mass. From the viewpoint of repulsion resistance and constant load peeling characteristics, a styrene block copolymer having a styrene content of 10% by mass or more (more preferably more than 10% by mass, for example, 12% by mass or more) is usually preferable. Further, from the viewpoint of cohesive force (holding force) of the pressure-sensitive adhesive and pressure-sensitive adhesive force to the adherend, the styrene content is 35% by mass or less (typically 30% by mass or less, more preferably 25% by mass or less, for example 20 Styrenic block copolymer of less than mass%) is preferred. In one embodiment of the technology disclosed herein, a styrene-based block copolymer having a styrene content of 10 to 35% by mass (more preferably more than 15% by mass and less than 24% by mass, for example, 16 to 23% by mass). Preferably it can be adopted. In another embodiment (for example, an embodiment including terpene phenol resins A and B having different hydroxyl values as a tackifying resin as described later), a styrene block copolymer having a styrene content of 12% by mass or more and less than 20% by mass. Coalescence can be preferably employed.

<Tackifying resin>
The pressure-sensitive adhesive in the technique disclosed herein contains a tackifying resin in addition to a base polymer (for example, a styrene block copolymer). As such a tackifier resin, one or more selected from various tackifier resins such as known petroleum resins, terpene resins, rosin resins, rosin derivative resins, and ketone resins can be used.
Examples of the petroleum resin include aliphatic (C5) petroleum resins, aromatic (C9) petroleum resins, C5 / C9 copolymer petroleum resins, alicyclic petroleum resins, hydrides thereof, and the like. The
As the terpene resin, terpene resins such as α-pinene polymer, β-pinene polymer, dipentene polymer (hereinafter referred to as “unmodified terpene resin” in order to clarify distinction from the modified terpene resin described later) Modified terpene resins obtained by modifying these terpene resins (phenol-modified, styrene-modified, hydrogenation-modified, hydrocarbon-modified, etc.). Examples of the modified terpene resin include terpene phenol resin, styrene-modified terpene resin, hydrogenated terpene resin, and the like.

  The above-mentioned “terpene phenol resin” refers to a polymer containing a terpene residue and a phenol residue, a copolymer of a terpene and a phenol compound (terpene-phenol copolymer resin), and a terpene homopolymer or copolymer. It is a concept that includes both a combination (terpene resin, typically unmodified terpene resin) and phenol-modified (phenol-modified terpene resin). Preferable examples of terpenes in the terpene phenol resin include monoterpenes such as α-pinene, β-pinene and limonene (including d-form, l-form and d / l-form (dipentene)).

  Specific examples of the “rosin-based resin” include unmodified rosins such as gum rosin, wood rosin, tall oil rosin (raw rosin); modified rosins modified by hydrogenation, disproportionation, polymerization, etc. (Hydrogenated rosin, disproportionated rosin, polymerized rosin, other chemically modified rosins, etc.). Examples of the rosin derivative resin include those obtained by esterifying unmodified rosin with alcohols (that is, rosin esterified products) and modified rosins (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) with alcohols. Rosin esters such as modified rosins (ie, esterified products of modified rosins); unmodified rosins and modified rosins (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) modified with unsaturated fatty acids Unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; Unmodified rosin, modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.), unsaturated fatty acid-modified rosins or unsaturated Rosin alcohols obtained by reducing carboxyl groups in fatty acid-modified rosin esters; unmodified rosin, modified rosin Metal salts of rosins (particularly rosin esters) such as rosin and various rosin derivatives; obtained by adding phenol to an rosin (unmodified rosin, modified rosin, various rosin derivatives, etc.) with an acid catalyst and thermal polymerization. Rosin phenol resin; and the like.

  The pressure-sensitive adhesive disclosed herein contains, as the tackifier resin, a low softening point resin having a softening point of less than 120 ° C. and a high softening point resin having a softening point of 120 ° C. or higher. The softening point of the tackifying resin here is defined as a value measured based on a softening point test method (ring ball method) defined in JIS K 5902 and JIS K 2207. Specifically, the sample is melted as quickly as possible, and is carefully filled so that no bubbles are formed in the ring placed on a flat metal plate. After cooling, cut off the raised part from the plane including the top of the ring with a slightly heated sword. Next, a supporter (ring stand) is put 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 so as not to contact each other, and the temperature of glycerin is maintained at 20 ° C. plus or minus 5 ° C. for 15 minutes. . Next, a steel ball is placed on the center of the surface of the sample in the ring, and this is placed in a fixed position on the support. Next, the distance from the upper end of the ring to the glycerin surface is maintained 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 is placed between the center and the edge of the bottom of the container so that the heating is even. It should be noted that the rate at which the bath temperature rises after reaching 40 ° C. after heating has started must be 5.0 plus or minus 0.5 ° C. per minute. The temperature at the time when the sample gradually softens and flows down from the ring and finally comes into contact with the bottom plate is read and used as the softening point. Two or more softening points are measured simultaneously, and the average value is adopted.

<High softening point resin>
The pressure-sensitive adhesive disclosed herein is characterized by containing a terpene phenol resin as the high softening point resin. Usually, a terpene phenol resin having a softening point of 120 ° C. or higher and 200 ° C. or lower (typically 120 ° C. or higher and 180 ° C. or lower, eg, 125 ° C. or higher and 170 ° C. or lower) can be preferably used. When the softening point is too low, the repulsion resistance and the resistance to constant load peeling may tend to be lowered. If the softening point is too high, the adhesive strength (particularly, the adhesive strength under low temperature conditions) to the adherend may tend to decrease.

  The hydroxyl value (OH value) of the terpene phenol resin is preferably 80 mgKOH / g or more (typically 80 to 200 mgKOH / g), preferably 90 mgKOH / g or more (typically 90 to 180 mgKOH / g). More preferably, it is 100 mgKOH / g or more (typically 100 to 180 mgKOH / g, for example, 110 to 180 mgKOH / g). The pressure-sensitive adhesive sheet using such a terpene phenol resin having a hydroxyl value is, for example, continuous compared to a pressure-sensitive adhesive sheet using only a terpene phenol resin having a lower hydroxyl value (for example, a hydroxyl value of about 60 mgKOH / g). Resistance to stress (particularly resistance to wet heat conditions) can be significantly improved. Therefore, according to the terpene phenol resin having such a hydroxyl value, a pressure-sensitive adhesive sheet excellent in the balance of adhesive strength, repulsion resistance, and constant load peeling characteristics can be realized. Furthermore, you may use the terpene phenol resin whose hydroxyl value is 120-170 mgKOH / g.

As the value of the hydroxyl value, a value measured by a potentiometric titration method defined in JIS K 0070: 1992 can be adopted. The specific measurement method is as follows.
[Measurement method of hydroxyl value]
1. Reagent (1) As an acetylating reagent, about 12.5 g (about 11.8 ml) of acetic anhydride is taken, and pyridine is added to this to make a total volume of 50 ml, which is used after sufficiently stirring. Alternatively, about 25 g (about 23.5 ml) of acetic anhydride is taken, pyridine is added thereto to make a total volume of 100 ml, and the mixture is sufficiently stirred.
(2) A 0.5 mol / l potassium hydroxide ethanol solution is used as a measuring reagent.
(3) Prepare toluene, pyridine, ethanol and distilled water.
2. Operation (1) About 2 g of a sample is accurately weighed in a flat bottom flask, 5 ml of an acetylating reagent and 10 ml of pyridine are added, and an air cooling tube is attached.
(2) The flask was heated in a bath at 100 ° C. for 70 minutes, then allowed to cool, and 35 ml of toluene was added as a solvent from the top of the condenser and stirred, and then 1 ml of distilled water was added and stirred to acetic anhydride. Disassemble. Heat again in the bath for 10 minutes to complete decomposition and allow to cool.
(3) Wash the cooling tube with 5 ml of ethanol and remove it. Next, 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 with 0.5 mol / l potassium hydroxide ethanol solution. The inflection point of the obtained titration curve is the end point.
(6) In the blank test, the above (1) to (5) are performed without putting a sample.
3. Calculation The hydroxyl value is calculated by the following formula.
Hydroxyl value (mgKOH / g) = [(BC) × f × 28.05] / S + D
here,
B: Amount of 0.5 mol / l potassium hydroxide ethanol solution used for the blank test (ml),
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: Mass of sample (g),
D: Acid value,
28.05: 1/2 of the molecular weight of potassium hydroxide 56.11,
It is.

  The pressure-sensitive adhesive disclosed herein may contain other resins as the high softening point resin in addition to the terpene phenol resin. Preferable examples of the high softening point resin that can be used in combination with the terpene phenol resin include polymerized rosin and esterified products of polymerized rosin. It is preferable that 25% by mass or more (more preferably 30% by mass or more) of the entire high softening point resin is a terpene phenol resin. 50% by mass or more (more preferably 70% by mass or more, more preferably 80% by mass or more, for example 90% by mass or more) of the high softening point resin may be a terpene phenol resin. All (for example, 95% by mass or more) may be a terpene phenol resin. For example, substantially all of the high softening point resin may be terpene phenol resin A and terpene phenol resin B described later.

  The content of the high softening point resin can be, for example, 20 to 100 parts by mass with respect to 100 parts by mass of the base polymer, exceeds 35 parts by mass and is 80 parts by mass or less (for example, 40 to 70 parts by mass). It is preferable to do. If the content of the high softening point resin is too small, the repulsion resistance and the constant load peeling property may tend to be lowered. If the content of the high softening point resin is too large, the adhesive force may tend to decrease. The technology disclosed herein is preferably practiced in an embodiment containing 20 parts by mass or more (preferably 35 parts by mass or more, for example, 40 parts by mass or more) of terpene phenol resin as a high softening point resin with respect to 100 parts by mass of the base polymer. Can be done. Usually, the content of the terpene phenol resin is suitably 100 parts by mass or less, preferably 80 parts by mass or less, for example 70 parts by mass or less.

<Low softening point resin>
As the low softening point resin, those having a softening point of 80 ° C. or higher and lower than 120 ° C. (more preferably 100 ° C. or higher and 120 ° C. or lower, for example, 110 ° C. or higher and 120 ° C. or lower) can be preferably used. When the softening point is too low, the constant load peeling property may tend to be lowered. When the softening point is too high, the adhesive force to the adherend may tend to decrease.

  The pressure-sensitive adhesive disclosed herein can be preferably implemented in a mode in which the pressure-sensitive adhesive contains at least one of a petroleum resin and a terpene resin (typically an unmodified terpene resin) as the low softening point resin. For example, the main component of the low softening point resin (that is, the component occupying more than 50% by mass of the low softening point resin) is a composition that is a petroleum resin, a composition that is a terpene resin, or a combination of a petroleum resin and a terpene resin. A certain composition can be preferably employed. As the petroleum resin, a C5 petroleum resin (typically, a resin obtained by polymerizing a residue obtained by extracting and separating isoprene and cyclopentadiene from a C5 fraction obtained by decomposition of naphtha) can be preferably used. As the terpene resin, a polymer of monoterpene such as α-pinene, β-pinene, limonene (including d-form, l-form and d / l-form (dipentene)) can be preferably used. From the viewpoint of adhesive strength and compatibility, the main component of the low softening point resin is preferably a terpene resin (for example, β-pinene polymer). Substantially all of the low softening point resin (for example, 95% by mass or more) may be a terpene resin.

  The content of the low softening point resin can be, for example, 10 to 120 parts by mass with respect to 100 parts by mass of the base polymer, and usually 15 to 90 parts by mass (for example, 20 to 70 parts by mass) is appropriate. It is. If the content of the low softening point resin is too small, the adhesive force to the adherend may tend to decrease. When the content of the low softening point resin is too large, the adhesive strength (particularly, the adhesive strength under low temperature conditions) may tend to decrease.

  The content of tackifying resin (total amount of low softening point resin and high softening point resin) relative to 100 parts by weight of the base polymer is usually 20 parts by weight or more (typically 20 to 200 parts by weight). It is suitable and it is preferable to set it as 30-150 mass parts (for example, 50-150 mass parts). When there is too much content of tackifying resin, adhesive force (especially adhesive force in low temperature conditions) may become a tendency to fall. If the content of the tackifying resin is too small, resistance to continuous stress (repulsion resistance, constant load peeling characteristics, etc.) may tend to decrease. The relationship between the amount of the low softening point resin and the high softening point resin is such that the mass ratio of the low softening point resin to the high softening point resin is 1: 5 to 3: 1 (more preferably 1: 5 to 2: 1). It is preferable to set so that The technique disclosed herein is preferably an embodiment containing a higher softening point resin than a low softening point resin (for example, a mass ratio of low softening point resin: high softening point resin is 1: 1.2 to 1: 5). Can be implemented. According to this aspect, a pressure-sensitive adhesive sheet superior in resistance to continuous stress (for example, constant load peeling characteristics) can be realized.

<Combination of terpene phenol resins having different hydroxyl values>
The pressure-sensitive adhesive composition disclosed herein is a form containing a base polymer composed of a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound, and a tackifier resin, and the terpene phenol as the tackifier resin It can be preferably implemented in a form containing at least the resin A and the terpene phenol resin B. Here, the terpene phenol resin A and the terpene phenol resin B have a hydroxyl value A _OH (mg KOH / g) of the terpene phenol resin A and a hydroxyl value B _OH (mg KOH / g) of the terpene phenol resin B of A _OH > B _OH It is preferable to select so as to satisfy the relationship. By using the terpene phenol resins A and B in combination, for example, the peel strength (particularly, peel strength after time) of the pressure-sensitive adhesive sheet can be improved.

Typically, the difference between the hydroxyl value _{A OH} and hydroxyl value _{B OH,} i.e. _A OH _{-B OH} is such that the larger 200 mg KOH / g or less than 0, it is appropriate to select a terpene phenol resin A, B . In a preferred embodiment, A _OH -B _OH is 5 to 150 mg KOH / g (typically 10 to 120 mg KOH / g, more preferably 15 to 100 mg KOH / g, such as 20 to 80 mg KOH / g or less).

The hydroxyl value of each of the terpene phenol resins A and B is not particularly limited. For _{example, A OH} and _{B OH} are both 80 mg KOH / g or more (typically 80~250mgKOH / g, preferably 80~220mgKOH / g, for example 90~160mgKOH / g) may _{be, A OH} and B _OH is less than both 80 mg KOH / g (typically less than 0 or 80 mg KOH / g, preferably less than 10 mgKOH / g or higher 80 mg KOH / g, for example 20~70mgKOH / g) may _{be, a OH} is 80 mg KOH / g not less _{than, B OH} may be less than 80 mg KOH / g. In a preferred embodiment, A _OH is 80 mg KOH / g or more (typically 80 to 160 mg KOH / g, preferably 80 to 140 mg KOH / g, such as 90 to 120 mg KOH / g), and B _OH is less than 80 mg KOH / g (typical thereof include 0 to less than 80 mg KOH / g, preferably less than 10 mgKOH / g or higher 80 mg KOH / g, for example 20~70mgKOH / g) and is, and _a OH _{-B OH} is 10 mgKOH / g or more (preferably 20 mgKOH / g or more, For example, it is 30 mgKOH / g or more, and typically 100 mgKOH / g or less).

  Each content of terpene phenol resin A and B can be 1 mass part or more with respect to 100 mass parts of base polymers, respectively. In order to better demonstrate the effect of using the terpene phenol resin A and the terpene phenol resin B in combination, the content of the terpene phenol resins A and B with respect to 100 parts by mass of the base polymer is 5 parts by mass or more ( It is preferably 10 parts by mass or more, for example, 15 parts by mass or more. In addition, from the viewpoint of adhesive strength to an adherend (particularly, adhesive strength at low temperature), the total content of terpene phenol resins A and B is usually 100 parts by mass or less with respect to 100 parts by mass of the base polymer. Is preferably 90 parts by mass or less, more preferably 80 parts by mass or less (for example, 70 parts by mass or less). For example, an embodiment in which the total content of the terpene phenol resins A and B with respect to 100 parts by mass of the base polymer is 15 to 80 parts by mass (typically 25 to 60 parts by mass) can be preferably adopted.

The mass ratio (m _A : m _B ) between the content m _A of the terpene phenol resin _A and the content m _B of the terpene phenol resin B can be, for example, 1:10 to 10: 1. Adhesive strength (peel strength) to adherend and balance between repulsion resistance (especially repulsion resistance under wet heat conditions) and constant load peel characteristics (especially constant load peel characteristics under wet heat conditions) From the viewpoint, normally, the mass ratio (m _A : m _B ) is suitably 1: 5 to 5: 1, and can be, for example, 1: 3 to 3: 1. In a preferred embodiment, the mass ratio _m A / _{m B} is 0.7 to 10 (more preferably 0.8 to 5, typically 0.9 to 4, e.g., 1 to 3) and so as to _m A, m _B can be set. According to such an embodiment, a pressure-sensitive adhesive sheet having excellent resistance to continuous stress and excellent temporal stability of adhesive performance (for example, peel strength) can be realized.

  The softening points of the terpene phenol resins A and B are not particularly limited. For example, the softening points of the terpene phenol resins A and B are both 120 ° C. or higher (typically higher than 120 ° C., preferably 125 ° C. or higher, such as 130 ° C. or higher, typically 180 ° C. or lower). Both may be less than 120 ° C. Moreover, the softening point of any one of terpene phenol resin A and B may be 120 degreeC or more, and the other softening point may be less than 120 degreeC. In a preferred embodiment, the terpene phenol resins A and B each have a softening point in the range of 120 ° C to 170 ° C. For example, terpene phenol resin A having a softening point of 120 ° C to 170 ° C and a hydroxyl value of 80 to 140 mgKOH / g, and a softening point of 120 ° C to 170 ° C and a hydroxyl value of less than 80 mgKOH / g (for example, 20 A combination with terpene phenol resin B which is ˜70 mg KOH / g) can be preferably employed.

  In addition, the adhesive composition disclosed here may further contain terpene phenol resins other than the terpene phenol resin A and the terpene phenol resin B as the tackifier resin. When the pressure-sensitive adhesive composition contains three or more types of terpene phenol resins, the two types are selected in order from the terpene phenol resins having the highest mass-based content, and the one with the higher hydroxyl value is selected. The terpene phenol resin A and the lower hydroxyl value are referred to as terpene phenol resin B. In addition, for example, as the terpene phenol resin having the highest content on a mass basis, when three types of terpene phenol resins are included at a mass ratio of approximately 1: 1: 1, the one having the highest hydroxyl value is selected. The terpene phenol resin A is used, and the terpene phenol resin B is the one having the lowest hydroxyl value.

<Isocyanate compound>
The technique disclosed here can be preferably implemented in a mode in which the pressure-sensitive adhesive further contains an isocyanate compound in addition to the base polymer and the tackifying resin. According to such an embodiment, resistance to continuous stress (for example, repulsion resistance) can be further improved. As the isocyanate compound, polyfunctional isocyanate (refers to a compound having an average of 2 or more isocyanate groups per molecule, including those having an isocyanurate structure) can be preferably used. As this polyfunctional isocyanate, 1 type (s) or 2 or more types selected from the various isocyanate compounds (polyisocyanate) which have a 2 or more isocyanate group in 1 molecule can be used. Examples of such polyfunctional isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates and the like.

  Specific examples of the aliphatic polyisocyanates include 1,2-ethylene diisocyanate; tetramethylene diisocyanate such as 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate, 1,4-tetramethylene diisocyanate; -Hexamethylene diisocyanate such as hexamethylene diisocyanate, 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,5-hexamethylene diisocyanate; Examples include 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and lysine diisocyanate.

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

  Specific examples of the aromatic polyisocyanates include 2,4-tolylene diisocyanate, 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-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxy Diphenyl-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate.

  Examples of preferred isocyanate compounds include polyfunctional isocyanates having an average of 3 or more isocyanate groups per molecule. Such a trifunctional or higher functional isocyanate is a difunctional or trifunctional or higher polymer (typically a dimer or trimer), a derivative (for example, a polyhydric alcohol and two or more polyfunctional isocyanates). Addition reaction product), polymer and the like. For example, diphenylmethane diisocyanate dimer or trimer, hexamethylene diisocyanate isocyanurate (trimer adduct of isocyanurate structure), reaction product of trimethylolpropane and tolylene diisocyanate, trimethylolpropane and hexamer Examples of the reaction product with methylene diisocyanate include polyfunctional isocyanates such as polymethylene polyphenyl isocyanate, polyether polyisocyanate, and polyester polyisocyanate. As commercial products of such polyfunctional isocyanates, trade names “Duranate TPA-100” manufactured by Asahi Kasei Chemicals, trade names “Coronate L”, “Coronate HL”, “Coronate HK” manufactured by Nippon Polyurethane Industry Co., Ltd. “Coronate HX”, “Coronate 2096” and the like.

  When using an isocyanate compound, it is appropriate that the amount used is more than 0 parts by mass and 10 parts by mass (typically 0.01 to 10 parts by mass) with respect to 100 parts by mass of the base polymer. Usually, 0.1 to 10 parts by mass (for example, 0.5 to 5 parts by mass) is preferable. By using an isocyanate compound within such a range, a pressure-sensitive adhesive sheet having an excellent performance balance can be realized. From the standpoint of adhesion between the base material (for example, a plastic film such as a polyethylene terephthalate (PET) film) and the pressure-sensitive adhesive layer, the amount is more than 0.1 parts by mass with respect to 100 parts by mass of the base polymer. It is preferable to use an amount (for example, 0.2 parts by mass or more, more preferably 0.3 parts by mass or more) of an isocyanate compound. In a preferred embodiment of the technology disclosed herein, the use amount of the isocyanate compound with respect to 100 parts by mass of the base polymer, etc., from the viewpoint of balance between the anchoring property with respect to the base material and the adhesive strength (peeling strength) with respect to the adherend, It is appropriate to set it to more than 0.1 mass part and 5 mass parts or less (typically 0.3-3 mass parts, for example, 0.5-1 mass part).

  The pressure-sensitive adhesive in the technology disclosed herein may contain one or more rubbery polymers other than the base polymer, if necessary. Such rubber-like polymers may 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. As the rubber-based rubber-like polymer, for example, natural rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), isoprene rubber, chloroprene rubber, polyisobutylene, butyl rubber, recycled rubber and the like can be used. . The amount used in the case of using the rubbery polymer is usually 50 parts by mass or less per 100 parts by mass of the base polymer, preferably 30 parts by mass or less, more preferably 10 parts by mass or less (for example, 5 parts by mass). Part or less). The technique disclosed herein can be preferably implemented in an embodiment that does not substantially contain such a rubbery polymer (for example, the content per 100 parts by mass of the base polymer is 0 to 1 part by mass).

  The pressure-sensitive adhesive disclosed herein may be a leveling agent, a crosslinking agent, a crosslinking aid, a plasticizer, a softening agent, a filler, a colorant (pigment, dye, etc.), an antistatic agent, an anti-aging agent, if necessary. It may contain various additives that are common in the field of pressure-sensitive adhesives, such as ultraviolet absorbers, antioxidants, and light stabilizers. About such various additives, a conventionally well-known thing can be used by a conventional method. The pressure-sensitive adhesive disclosed herein contains substantially no liquid rubber such as polybutene (for example, the content per 100 parts by mass of the base polymer may be 1 part by mass or less, and may be 0 part by mass). The embodiment can be preferably implemented. According to the pressure-sensitive adhesive, a pressure-sensitive adhesive sheet having more excellent repulsion resistance and / or constant load peeling characteristics can be realized.

  In the pressure-sensitive adhesive disclosed herein, the total amount of the base polymer and the tackifying resin is 90% by mass or more (typically 90 to 99.5% by mass, for example, 95 to 99% by mass) of the pressure-sensitive adhesive. It can be preferably implemented in an occupied manner. The pressure-sensitive adhesive is a chelate compound (for example, a chelate compound of an alkaline earth metal oxide and a resin (an alkylphenol resin or the like) having a functional group (a hydroxyl group, a methylol group, or the like) to which the oxide can coordinate). It can be preferably implemented in an embodiment that does not substantially contain (for example, an embodiment in which such a chelate compound is not contained at all or its content is 1% by mass or less of the pressure-sensitive adhesive). According to such an embodiment, a pressure-sensitive adhesive sheet with more excellent adhesive strength can be realized.

  The form of the pressure-sensitive adhesive composition disclosed herein is not particularly limited. For example, the pressure-sensitive adhesive composition or pressure-sensitive adhesive in a form (solvent type) containing a pressure-sensitive adhesive (pressure-sensitive adhesive component) as described above in an organic solvent. Can be a pressure-sensitive adhesive composition in a form dispersed in an aqueous solvent (water-dispersed type, typically an aqueous emulsion type), a hot-melt type pressure-sensitive adhesive composition, and the like. From the viewpoints of coating properties and the degree of freedom in selecting a substrate, a solvent-type or water-dispersed pressure-sensitive adhesive composition can be preferably employed. In order to realize higher adhesive performance, a solvent-type adhesive composition is particularly preferable. Such a solvent-type pressure-sensitive adhesive composition is typically prepared in the form of a solution containing the above-described 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); acetates such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane, cyclohexane, and methylcyclohexane Any one solvent selected from the group: halogenated alkanes such as 1,2-dichloroethane; ketones such as methyl ethyl ketone and acetylacetone; and a mixed solvent of two or more. Although not particularly limited, it is usually appropriate to prepare the solvent-based pressure-sensitive adhesive composition to a solid content (NV) of 30 to 65% by mass (for example, 40 to 55% by mass). When NV is too low, the manufacturing cost tends to be high, and when NV is too high, handling properties such as coatability may be lowered.

  When the technology disclosed herein is applied to a double-sided PSA sheet with a substrate or a single-sided PSA sheet with a substrate, examples of the substrate include a polypropylene film, an ethylene-propylene copolymer film, a polyester film, and a polyvinyl chloride film. Foam sheets made of foams such as polyurethane foam, polyethylene foam, polychloroprene foam; various fibrous materials (natural fibers such as hemp and cotton; synthetic fibers such as polyester and vinylon; semi-finished materials such as acetate A woven fabric and a non-woven fabric (meaning including papers such as Japanese paper and fine paper)); metal foils such as aluminum foil and copper foil; etc. It can be appropriately selected and used depending on the application of the pressure-sensitive adhesive sheet. As the plastic film (typically a non-porous plastic film, which is a concept distinguished from a woven fabric or a non-woven fabric), any of an unstretched film and a stretched (uniaxially stretched or biaxially stretched) film is used. Can also be used. Further, the surface of the substrate on which the pressure-sensitive adhesive layer is provided may be subjected to surface treatment such as application of a primer and corona discharge treatment. The thickness of the substrate can be appropriately selected depending on the purpose, but is generally about 2 μm to 500 μm (typically 10 μm to 200 μm).

  As a method for forming the pressure-sensitive adhesive layer on the substrate, various conventionally known methods can be applied. For example, a method in which the pressure-sensitive adhesive composition is directly applied to a substrate and dried (direct method), and the pressure-sensitive adhesive composition is applied on a suitable release surface and dried to adhere to the release surface. Examples thereof include a method (transfer method) in which an agent layer is formed and the pressure-sensitive adhesive layer is bonded to a substrate and transferred. You may use combining these methods. Application of the pressure-sensitive adhesive composition can be performed 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 crosslinking reaction and improving the production efficiency, the pressure-sensitive adhesive composition is preferably dried under heating. Usually, for example, a drying temperature of about 40 ° C. to 120 ° C. can be preferably used. Although not particularly limited, the thickness of the pressure-sensitive adhesive layer is usually about 4 μm to 150 μm (typically 20 μm to 120 μm, for example, 30 μm to 100 μm). In the case of a double-sided pressure-sensitive adhesive sheet with a substrate, it is preferable that a pressure-sensitive adhesive layer having the above thickness is provided on each side of the substrate.

  The pressure-sensitive adhesive sheet disclosed herein was pressure-bonded by reciprocating a 2 kg roller on the surface of a stainless steel (SUS304) plate as an adherend in an environment of 23 ° C. and 50% RH and left for 30 minutes. Thereafter, 180 ° peel adhesion (N / 20 mm width) measured under conditions of a tensile speed of 300 mm / min in accordance with JIS Z 0237 (more specifically, according to the 180 ° peel strength evaluation method described in Examples described later) Is typically 10 N / 20 mm or more. The 180 ° peeling adhesive strength is preferably 15 N / 20 mm or more, and more preferably 20 N / 20 mm or more. Such an adhesive sheet is suitable for, for example, a use for fixing a resin component (such as the resin blade 30 shown in FIG. 2) to another resin component (such as the plastic molded body 36 shown in FIG. 2). In the pressure-sensitive adhesive sheet according to a preferred embodiment, the 180 ° peel-off adhesive strength (N / 20 mm width) may be 25 N / 20 mm or more (more preferably 30 N / 20 mm or more).

  The pressure-sensitive adhesive sheet disclosed herein is measured by applying the condition (C) using an acrylonitrile styrene butadiene copolymer resin (ABS) plate as an adherend in the repulsion resistance evaluation method described in Examples described later. The floating distance may be 3 mm or less. In a preferred embodiment, the floating distance is 2 mm or less (for example, 1 mm or less). Further, the pressure-sensitive adhesive sheet disclosed herein has a 15 mm peel distance after 18 hours measured under wet heat conditions using an ABS plate as an adherend in the constant load peel property evaluation method described in the examples described later. Or less (typically 10 mm or less, preferably 5 mm or less, for example 3 mm or less).

The matters disclosed by this specification include the following.
(1) A pressure-sensitive adhesive composition containing a base polymer and a tackifying resin,
The base polymer is a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound,
The tackifying resin contains a low softening point resin having a softening point of less than 120 ° C and a high softening point resin having a softening point of 120 ° C or more,
The high softening point resin is a pressure-sensitive adhesive composition containing a terpene phenol resin.
(2) The pressure-sensitive adhesive composition according to (1), wherein the base polymer has a diblock body ratio of 50% or more.
(3) The pressure-sensitive adhesive composition according to (1) or (2) above, wherein the base polymer is a styrene block copolymer.
(4) The pressure-sensitive adhesive composition according to any one of (1) to (3), wherein the base polymer comprises at least one of a styrene isoprene block copolymer and a styrene butadiene block copolymer.
(5) The high softening point resin according to any one of (1) to (4), wherein 25% by mass or more (typically 25% by mass or more and 100% by mass or less) is a terpene phenol resin. Adhesive composition.
(6) The pressure-sensitive adhesive composition according to any one of (1) to (5), wherein the terpene phenol resin has a hydroxyl value of 80 mgKOH / g or more (more preferably 110 mgKOH / g or more).
(7) The pressure-sensitive adhesive composition according to any one of (1) to (6), wherein 20 to 100 parts by mass of the high softening point resin is contained with respect to 100 parts by mass of the base polymer.
(8) The pressure-sensitive adhesive composition according to any one of (1) to (7), wherein the low softening point resin includes at least one of a petroleum resin and a terpene resin.
(9) The pressure-sensitive adhesive composition according to any one of (1) to (8), further comprising a polyfunctional isocyanate.
(10) The pressure-sensitive adhesive composition according to (9), wherein the content of the polyfunctional isocyanate is 1 to 5 parts by mass per 100 parts by mass of the base polymer.
(11) A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from any pressure-sensitive adhesive composition disclosed herein.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples. In the following description, “parts” and “%” are based on mass unless otherwise specified. Each characteristic in the following description was measured or evaluated as follows.

(1) 180 degree peeling strength The peeling liner which covers one adhesive surface of a double-sided adhesive sheet was peeled off, it affixed on the 25-micrometer-thick polyethylene terephthalate (PET) film, and it lined. The backed adhesive sheet was cut into a size of 20 mm in width and 100 mm in length to produce a test piece. In an environment of 23 ° C. and 50% RH, the release liner covering the other adhesive surface of the test piece was peeled off, and the test piece was pressed against the surface of the adherend by reciprocating a 2 kg roller once. After leaving this in the same environment for 30 minutes, the adhesive strength (N / 20 mm width) was measured using a tensile tester in accordance with JIS Z 0237 at 180 ° peeled off at a tensile speed of 300 mm / min.
Stainless steel (SUS304) plate, ABS plate (manufactured by Shin-Kobe Electric Machinery Co., Ltd.), impact-resistant polystyrene (HIPS) plate (manufactured by Nippon Test Panel Co., Ltd.), and polycarbonate (PC) / ABS blend resin plate (Japan Test Panel Co., Ltd.) Adhesive strength was measured according to the above procedure.

(2) Resilience resistance The aluminum cylinder with a diameter of 24 mm was used for the adherend, and the resilience resistance of the double-sided PSA sheet was evaluated. That is, one pressure-sensitive adhesive surface 4A of the double-sided pressure-sensitive adhesive sheet 4 was attached to the PET film 42 having a thickness of 300 μm and lined (see FIG. 3). The backing adhesive sheet 4 was cut into a size of 10 mm width and 40 mm length to produce a test piece 44. As shown in FIG. 3, in the environment of 23 ° C. and 50% RH, the other adhesive surface 4B of the test piece 44 has a longitudinal direction of the test piece 44 in the circumferential direction of the adherend (aluminum cylinder) 46. Then, a 2 kg roller was reciprocated once and pressed. The adherend 46 was used after washing with ethyl alcohol in advance. After maintaining this in any of the following conditions (A) to (C), it was observed whether or not both ends 44A and 44B in the longitudinal direction of the test piece 44 were peeled off from the surface of the adherend 46 and floated. When it was floating, the floating distance (the length of the portion where the test piece 44 was lifted from the surface of the adherend 46) was measured. When both ends of the test piece were floating, the average value of the floating distances at both ends was taken as the floating distance of the test piece.
(A) Leave at room temperature (23 ° C., 50% RH) for 24 hours (B) Leave at 70 ° C. and 80% RH for 4 hours (C) Leave at 70 ° C. and 80% RH for 12 hours

(3) Constant load peeling characteristics One adhesive surface 5A of the double-sided pressure-sensitive adhesive sheet 5 was attached to a PET film 52 having a thickness of 25 μm and lined (see FIG. 4). The backing adhesive sheet 5 was cut into a size of 10 mm in width and 100 mm in length to produce a test piece 54. Under the environment of 23 ° C. and 50% RH, the other adhesive surface 5B of the test piece 54 was pressed against the surface of the adherend 56 by reciprocating a 2 kg roller once. This was left in the same environment for 30 minutes. Thereafter, in an environment of 23 ° C. and 50% RH, as shown in FIG. 4, the adherend 56 was held horizontally such that the surface on which the test piece 54 was attached was downward. A load 58 of 300 g (2.9 N) was applied to one end of the test piece 54 so that the peel angle was 90 degrees, and the peel distance after 24 hours was measured. For three types of adherends, an ABS plate (manufactured by Shin-Kobe Electric Co., Ltd.), a PC / ABS blend resin plate (manufactured by Nippon Test Panel Co., Ltd.) and a HIPS plate (manufactured by Nippon Test Panel Co., Ltd.) The constant load peeling characteristics (peeling distance) below were measured.
Similarly, after the test piece is pressure-bonded to the adherend surface in an environment of 23 ° C. and 50% RH and left in the same environment for 30 minutes, it is then placed in an environment of 50 ° C. and 80% RH (wet heat condition). Then, the adherend is held horizontally so that the surface on which the test piece is attached is downward, and a load of 100 g (0.98 N) is applied to one end of the test piece so that the peel angle is 90 degrees. And the peel distance after 18 hours was measured. With respect to two types of adherends, an ABS plate (manufactured by Shin-Kobe Electric Machinery Co., Ltd.) and a HIPS plate (manufactured by Nippon Test Panel Co., Ltd.), constant load peel characteristics (peel distance) under wet heat conditions were measured according to the above procedure.

<Experimental example 1>
Styrene isoprene block copolymer (JSR Corporation product, product name “SIS5505”, diblock body ratio 50%, styrene content 16%) and C5 petroleum resin as a low softening point resin at the ratio shown in Table 1. (Zeon Corporation product, product name “Quinton (registered trademark) U-185” (hereinafter simply referred to as “U-185”), softening point 86 ° C., hydroxyl value of less than 1 mg KOH / g) and high softening Terpene phenol resin as a point resin (product of Yasuhara Chemical Co., Ltd., product name “S145”, softening point 145 ° C., hydroxyl value 100 KOHmg / g) and / or rosin ester (product of Arakawa Chemical Co., Ltd., product name “D125”, softening point) 125 ° C., hydroxyl value 40 mgKOH / g) and toluene as a solvent are mixed by stirring to give a solid content (NV) 50% adhesive. The composition a1~a6 was prepared.

  Each of the pressure-sensitive adhesive compositions a1 to a6 is applied to the first surface of a polyethylene terephthalate (PET) film (trade name “Lumirror S10”, manufactured by Toray Industries, Inc.) having a thickness of 12 μm as a base material. Was dried for 3 minutes to form an adhesive layer having a thickness of 64 μm. A release liner subjected to a release treatment with a silicone release agent was bonded to the pressure-sensitive adhesive layer. Next, a pressure-sensitive adhesive layer having a thickness of 64 μm was formed on the second surface (surface opposite to the first surface) of the PET film, and a release liner was bonded thereto. Thus, the double-sided adhesive sheets a1-a6 corresponding to each adhesive composition a1-a6 were produced. Table 1 shows the schematic configuration and evaluation results of these double-sided PSA sheets. FIG. 5 is a graph showing the evaluation results of repulsion resistance.

  As shown in these charts, a1 to a3 and a5 double-sided PSA sheets using terpene phenol resin alone as a high softening point resin are combined with double-sided PSA sheet a6 using rosin ester alone as a high softening point resin. In comparison, the repulsion resistance under wet heat conditions was clearly better. Also in a4 using terpene phenol resin and rosin ester at a mass ratio of 1: 2 as the high softening point resin, the improvement in repulsion resistance was clearly seen as compared with the double-sided PSA sheet a6. When the total amount of the high softening point resin with respect to 100 parts of the base polymer exceeds 30 parts (for example, 35 parts or more and 60 parts by weight or less), a larger repulsion resistance improvement effect was obtained. Further, the ratio of the high softening point resin / low softening point resin exceeds 1 (for example, 1.2 or more and 5.0 or less), a2 to a4, compared with a1, 5, and 6 where the ratio is 1 or less. It showed better constant load peeling properties.

<Experimental example 2>
A styrene isoprene block copolymer (shown as “SIS” in the table) or a styrene butadiene block copolymer (shown as “SBS” in the table) having the diblock ratio and styrene content shown in Tables 2 and 3. Used to prepare pressure-sensitive adhesive compositions b1 to b13. That is, in the proportions shown in Tables 2 and 3, each styrene block copolymer, a C5 petroleum resin (product of Nippon Zeon Co., Ltd., product name “U-185”) as a low softening point resin, and a high softening point. A terpene phenol resin (product of Yashara Chemical Co., Ltd., product name “S145”) as a resin and toluene as a solvent were mixed with stirring to prepare adhesive compositions b1 to b13 of NV50%. The styrene block copolymers used in b1, 6, 8, 9, and 12 are manufactured by JSR Corporation, and the styrene block copolymers used in b2 to 5, 7, 10, and 11 are Kraton Polymer Japan Co., Ltd. The styrene block copolymer used in B13 is manufactured by Nippon Zeon Co., Ltd.
Using each of these pressure-sensitive adhesive compositions b1 to b13, double-sided pressure-sensitive adhesive sheets b1 to b13 were produced in the same manner as in Experimental Example 1. Tables 2 and 3 show the schematic configuration and evaluation results of each double-sided PSA sheet.

  As shown in the above table, the double-sided pressure-sensitive adhesive sheets b1 to b3 and b13 using a styrene isoprene block copolymer having a diblock ratio of 30 to 80% (more preferably 50 to 80%) as a base polymer are as follows: As compared with the double-sided pressure-sensitive adhesive sheet having a lower diblock body ratio, the repulsion resistance (particularly, the repulsion resistance under wet heat conditions) tended to be excellent.

<Experimental Example 3: Use of Isocyanate Compound>
In the proportions shown in Table 4, styrene isoprene block copolymer (JSR Corporation product, product name “SIS5505”) and C5 petroleum resin (Nippon Zeon Corporation product, product name “U-185” as a low softening point resin). )), A terpene phenol resin as a high softening point resin (product of Yasuhara Chemical Co., Ltd., product name “S145”), an isocyanate compound (product of Japan Polyurethane Industry Co., Ltd., product name “Coronate L”), toluene as a solvent, Were mixed by stirring to prepare pressure-sensitive adhesive compositions c1 to c4 having an NV of 50%. Further, a pressure-sensitive adhesive composition c5 was prepared in the same manner as described above except that the isocyanate compound was not used. Using each of these pressure-sensitive adhesive compositions c1 to c5, double-sided pressure-sensitive adhesive sheets c1 to c5 were produced in the same manner as in Experimental Example 1. Table 4 shows the schematic configuration and evaluation results of each double-sided PSA sheet. FIG. 6 is a graph showing the evaluation results of repulsion resistance.

  As shown in these charts, according to the c1 to c4 double-sided pressure-sensitive adhesive sheet using 1 to 5 parts of isocyanate compound per 100 parts of the base polymer, compared with the c5 double-sided pressure-sensitive adhesive sheet without using the isocyanate compound, the wet heat conditions The repulsion resistance below was further improved. In addition, c3 and c4 which used the usage-amount of the isocyanate compound 3 parts or more had the tendency for 180 degree | times peeling strength to fall a little. This result shows that, in an application in which 180 degree peel strength is important, the amount of the isocyanate compound used is approximately 2.5 parts or less per 100 parts of the styrenic block copolymer (typically 0.3 to 2.5 parts). , For example, about 0.5 to 2.5 parts) is suggested.

<Experimental Example 4: Examination of low softening point resin>
In the proportions shown in Table 5, styrene isoprene block copolymer (JSR Corporation product, product name “SIS5505”), low softening point resin, and terpene phenol resin as high softening point resin (Yasuhara Chemical Co., Ltd. product, product name) “S145”), an isocyanate compound (product of Nippon Polyurethane Industry Co., Ltd., product name “Coronate L”, isocyanate content 13.6%) and toluene as a solvent are mixed with stirring, and an adhesive composition d1 of NV 50% is obtained. -D7 was prepared. As a low softening point resin, product name “U-185” (C5 petroleum resin) manufactured by Nippon Zeon Co., Ltd., product name “S-100” manufactured by Nippon Zeon Corporation (C5 petroleum resin, softening point 94 ° C.) Or a product name “PX1150N” (terpene resin, softening point 115 ° C., hydroxyl value less than 1 mgKOH / g) manufactured by Yasuhara Chemical Co., Ltd. was used. Using each of these pressure-sensitive adhesive compositions d1 to d7, double-sided pressure-sensitive adhesive sheets d1 to d7 were produced in the same manner as in Experimental Example 1. Table 5 shows the schematic configuration and evaluation results of each double-sided PSA sheet.

  As shown in the above table, compared with d1 and d2 using C5 petroleum resin as the low softening point resin, the double-sided PSA sheet according to d3 to d7 using terpene resin tends to exhibit higher peel strength. there were. Further, the peel strength tends to increase as the amount of the low softening point resin added per 100 parts of the base polymer increases. However, from the viewpoint of the balance between the repulsion resistance and the constant load peeling property, the low softening point resin is used. In d3 to d5 in which the amount of is 80 parts or less (for example, 60 parts or less), better results were obtained.

<Experimental Example 5: Examination of high softening point resin>
In the ratio shown in Table 6, styrene isoprene block copolymer (JSR Corporation product, product name “SIS5505”) and C5 petroleum resin (Nippon Zeon Corporation product, product name “U-185” as a low softening point resin). )), A high softening point resin, an isocyanate compound (manufactured by Nippon Polyurethane Industry Co., Ltd., product name “Coronate L”), and toluene as a solvent are mixed by stirring to obtain adhesive compositions e1 to e7 of NV 50%. Prepared. As the high softening point resin, various terpene phenol resins having a softening point and a hydroxyl value shown in Table 6 (all manufactured by Yasuhara Chemical Co., Ltd.) were used. Using each of these pressure-sensitive adhesive compositions e1 to e7, double-sided pressure-sensitive adhesive sheets e1 to e7 were produced in the same manner as in Experimental Example 1. Table 6 shows the schematic configuration and evaluation results of each double-sided PSA sheet. FIG. 7 is a graph showing the evaluation results of repulsion resistance.

  As shown in these charts, the double-sided pressure-sensitive adhesive sheet of e3 to e7 using a terpene phenol resin having a hydroxyl value of 80 mgKOH / g or more (more specifically, 80 to 250 mgKOH / g) as a high softening point resin has a hydroxyl value. The resistance to continuous stress was clearly higher than the double-sided adhesive sheets of e1 and e2 using terpene phenol resin of 60 mgKOH / g or less. In particular, in repulsion resistance and constant load peeling characteristics under wet heat conditions, a remarkable effect is observed by using a terpene phenol resin having a hydroxyl value of 80 mgKOH / g or more (for example, 100 mgKOH / g or more), and a hydroxyl value of 110 mgKOH / g or more. Even better results were obtained with e4 to e7 using the terpene phenol resin.

<Experimental example 6>
In the ratio shown in Table 7, a styrene isoprene block copolymer as a base polymer (manufactured by Nippon Zeon Co., Ltd., product name “Quintac 3520”, diblock body ratio 78%, styrene content 15%), Terpene phenol resin (product of Yasuhara Chemical Co., product name “S145”) having a hydroxyl value of 100 mgKOH / g, terpene resin (product name “PX1150N” manufactured by Yasuhara Chemical Co., Ltd.), and isocyanate compound (product of Japan Polyurethane Industry Co., Ltd., product name) “Coronate L”) and toluene as a solvent were mixed with stirring to prepare pressure-sensitive adhesive compositions f1 to f6 of NV 50%. Using each of these pressure-sensitive adhesive compositions f1 to f6, in the same manner as in Experimental Example 1, double-sided pressure-sensitive adhesive sheets f1 to f6 having pressure-sensitive adhesive layers on both sides of a PET film (base material) were produced.

Table 7 shows the schematic configuration and evaluation results of each double-sided PSA sheet.
Here, the “peeling distance” of the constant load peeling characteristics shown in Table 7 is measured using an ABS plate (manufactured by Shin-Kobe Electric Co., Ltd.) as the adherend. Further, the “peeling mode” of the constant load peeling characteristics shown in Table 7 is an evaluation in which the tester visually confirms and evaluates the portion where the test piece is peeled off from the adherend in the peeling distance measurement. About this "peeling form", the "interface" shown in Table 7 is a form in which the adhesive sheet (test piece) 5 is peeled between the adherend 56 and the adhesive surface 5B, as in the example shown in FIG. That is, it refers to a form in which the pressure-sensitive adhesive is not left on the surface of the adherend 56. On the other hand, “throwing” in FIG. 4 is the relationship between the pressure-sensitive adhesive layer on the pressure-sensitive adhesive surface 5B side and the base material of the pressure-sensitive adhesive sheet 5 (base material 15 shown in FIG. 1; PET film having a thickness of 12 μm in this experimental example). The form which peeled between them, ie, the form from which the test piece peeled off leaving the adhesive layer of the adhesive surface 5B side on the to-be-adhered body 56 is shown.

  As shown in Table 7, the flea and f2 double-sided PSA sheets that did not use an isocyanate compound or the amount used was 0.1 part or less had a throwing peel in the constant load peel measurement. On the other hand, in the f3-f6 double-sided PSA sheet using more than 0.1 part (more specifically, 0.3 part or more) of isocyanate compound, the peeling form in the constant load peeling measurement was interface peeling. This result shows that in the double-sided pressure-sensitive adhesive sheet of f3 to f6, the anchoring property of the pressure-sensitive adhesive with respect to the base material (here, the PET film) is improved. On the other hand, when the amount of the isocyanate compound used increases, the peel strength tends to decrease. The results shown in Table 7 show that in the composition of this experimental example, the anchoring property and the peel strength are compatible at a particularly high level in the range where the amount of the isocyanate compound used is more than 0.3 part and less than 1.0 part. It is shown that.

<Experimental example 7>
Styrene isoprene block copolymer (manufactured by Zeon Corporation, product name “Quintac 3520”) as a base polymer and a terpene phenol resin having a hydroxyl value of 100 mg KOH / g (Yasuhara Chemical Co., Ltd.) at the ratio shown in Table 8. Product, product name “S145”), terpene phenol resin (product of Yasuhara Chemical Co., product name “T145”) having a hydroxyl value of 60 mgKOH / g, terpene resin (product name “PX1150N” manufactured by Yashara Chemical Co., Ltd.), and isocyanate A compound (Nippon Polyurethane Industry Co., Ltd., product name “Coronate L”) and toluene as a solvent were mixed with stirring to prepare pressure-sensitive adhesive compositions g1 to g5 of NV 50%. Using each of these pressure-sensitive adhesive compositions g1 to g5, as in Experimental Example 1, double-sided pressure-sensitive adhesive sheets g1 to g5 having pressure-sensitive adhesive layers on both sides of a PET film (base material) were produced.
In the adhesive compositions g2 to g4, the terpene phenol resin (S145) having a hydroxyl value of 100 mgKOH / g corresponds to the terpene phenol resin A, and the terpene phenol resin (T145) having a hydroxyl value of 60 mgKOH / g is a terpene phenol resin. Corresponds to B.

Table 8 shows the schematic configuration and evaluation results of each double-sided PSA sheet.
Here, the 180 degree peel strength is measured by using a stainless steel (SUS304) plate as an adherend, and after being prepared as described above, a double-sided pressure-sensitive adhesive sheet (initial), which is not particularly provided with a storage period, 23 ° C., 50% Double-sided pressure-sensitive adhesive sheet after holding for 7 days in RH environment (rt storage for 7 days), double-sided pressure-sensitive adhesive sheet after storage for 14 days in a 50% RH environment (14 days for rt storage), 40 ° C, Double-sided PSA sheet (3 days storage at 40 ° C and 92% RH) after being kept in a humid heat environment of 92% RH for 3 days and then returned to an environment of 23 ° C and 50% RH, wet heat of 40 ° C and 92% RH Double-sided pressure-sensitive adhesive sheet (7 days storage at 40 ° C. and 92% RH) after being kept in the environment for 7 days and then returned to the environment at 23 ° C. and 50% RH, and 14 in a wet heat environment of 40 ° C. and 92% RH Double-sided viscosity after being kept for 23 days and returned to an environment of 23 ° C and 50% RH Was performed on each sheet (40 ℃ 92% RH storage for 14 days). In addition, the constant load peel property is obtained by applying a load of 100 g (0.98 N) to one end of the test piece in an environment of 50 ° C. and 80% RH (wet heat condition) in the above-described evaluation of the constant load peel property. The time from measurement to measurement was changed from 18 hours to 24 hours, and evaluation was performed by measuring the peel distance of the test piece.

  As shown in Table 8, the terpene phenol resin (S145) having a hydroxyl value of 100 mgKOH / g alone is used as compared with the g1 double-sided pressure-sensitive adhesive sheet using only a terpene phenol resin having a hydroxyl value of 60 mgKOH / g (T145). Or, the g2 to g5 double-sided PSA sheet used in combination with T145 was clearly highly resistant to continuous stress. In particular, a remarkable improvement was observed in the constant load peeling characteristics under wet heat conditions, and it was confirmed that the same effects as in Experimental Example 1 (Table 1) were obtained even in the composition of this Experimental Example. Moreover, compared with g5 which uses only S145 as a terpene phenol resin, the peel strength after a lapse of time was clearly improved in g2 to g4 using a combination of S145 and T145. Among them, the g3 and g4 double-sided PSA sheet containing S145 0.9 to 4 times (more specifically 1 to 3 times) T145 on a mass basis has resistance to continuous stress and peeling after aging. The strength was compatible at a high level.

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

  The pressure-sensitive adhesive composition or pressure-sensitive adhesive sheet disclosed herein is useful for joining between members in various OA equipment, home appliances, automobiles, and the like (for example, for fixing various parts in such products). In particular, it is suitable for applications in which an elastic resin sheet (for example, a plastic film having a thickness of about 0.05 mm to 0.2 mm) is joined to a resin casing such as ABS, HIPS, PC / ABS, or the like. Examples of products having such joints include toner cartridges, printers, notebook computers, and mobile devices.

1, 2, 3, 4, 5 Adhesive sheet 11 First adhesive layer 12 Second adhesive layer 15 Base materials 21, 22 Release liner

Claims (13)

A pressure-sensitive adhesive composition containing a base polymer and a tackifying resin,
The base polymer is a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound,
The tackifying resin has a low softening point resin below the softening point of 120 ° C., a softening point contains a high softening point resin or higher 120 ° C., the high softening point resin is viewed contains a terpene phenol resin,
The tackifying resin contains a terpene phenol resin A and the terpene phenol resin B, the hydroxyl value _A OH of the terpene phenol resin A (mg KOH / g) had a hydroxyl value _B OH (mg KOH / g of the terpene phenol resin B ) Higher than the pressure-sensitive adhesive composition. The hydroxyl value _{A OH} terpene phenol resin A is 80 mg KOH / g or more, a hydroxyl value _{B OH} of the terpene phenol resin B is less than 80 mg KOH / g, pressure-sensitive adhesive composition according to claim 1. The mass ratio of the content _{m B} of the content of the terpene phenol resin A _{m A} and the terpene phenol resin _{B (m} A: m B) is 1: 5 to 5: 1, according to claim 1 or 2 Adhesive composition. The pressure-sensitive adhesive composition according to any one of claims 1 to 3 , wherein each of the terpene phenol resin A and the terpene phenol resin B is a high softening point resin having a softening point of 120 ° C or higher. A pressure-sensitive adhesive composition containing a base polymer and a tackifying resin,
The base polymer is a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound,
The tackifying resin contains a low softening point resin having a softening point of less than 120 ° C. and a high softening point resin having a softening point of 120 ° C. or more, and the high softening point resin has a hydroxyl value of 80 mgKOH / g or more. Including phenolic resin,
The pressure-sensitive adhesive composition further comprises an isocyanate compound. The pressure-sensitive adhesive composition contains terpene phenol resin A and terpene phenol resin B as the tackifier resin,
The pressure-sensitive adhesive composition according to claim 5 , wherein the hydroxyl value A _OH (mgKOH / g) of the terpene phenol resin A is higher than the hydroxyl value B _OH (mgKOH / g) of the terpene phenol resin B. The pressure-sensitive adhesive composition according to any one of claims 1 to 6, wherein the diblock body ratio of the base polymer is 50% by mass or more. The pressure-sensitive adhesive composition according to any one of claims 1 to 7 , wherein the base polymer is a styrenic block copolymer. The pressure-sensitive adhesive composition according to any one of claims 1 to 8 , comprising 20 to 100 parts by mass of the high softening point resin with respect to 100 parts by mass of the base polymer. The pressure-sensitive adhesive composition according to any one of claims 1 to 9 , wherein the low softening point resin includes at least one of a petroleum resin and a terpene resin.   The adhesive sheet which has an adhesive layer formed from the adhesive composition as described in any one of Claim 1 to 10. An adhesive sheet comprising an adhesive layer,
The pressure-sensitive adhesive layer contains a base polymer and a tackifying resin,
The base polymer is a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound,
The tackifying resin has a low softening point resin below the softening point of 120 ° C., a softening point contains a high softening point resin or higher 120 ° C., the high softening point resin is viewed contains a terpene phenol resin,
The tackifying resin contains a terpene phenol resin A and the terpene phenol resin B, the hydroxyl value _A OH of the terpene phenol resin A (mg KOH / g) had a hydroxyl value _B OH (mg KOH / g of the terpene phenol resin B ) Higher than the adhesive sheet. An adhesive sheet comprising an adhesive layer,
The pressure-sensitive adhesive layer contains a base polymer and a tackifier resin, and further contains an isocyanate compound,
The base polymer is a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound,
The tackifying resin contains a low softening point resin having a softening point of less than 120 ° C and a high softening point resin having a softening point of 120 ° C or more,
The high softening point resin is a pressure-sensitive adhesive sheet containing a terpene phenol resin having a hydroxyl value of 80 mgKOH / g or more.

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