Adhesive sheet

Abstract

The present invention relates to an adhesive sheet. The present invention provides an adhesive sheet comprising a fibrous sheet and an adhesive layer laminated on the fibrous sheet. The above-mentioned adhesive layer comprises a base polymer and a tackifying resin. The above-mentioned base polymer is a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound. The above-mentioned tackifying resin contains a tackifying resin having a softening point of less than 120°C and a tackifying resin having a softening point of 120°C or more. The thickness of the above-mentioned fibrous sheet is 15 μm or more and 50 μm or less, and the bulk density is 0.25 g / cm 3 or more and 0.50 g / cm 3 or more.

Description

[0001] This application is a divisional application of Chinese patent application No. 202080017896.8, filed on February 13, 2020, entitled "Adhesive Sheet". Technical Field

[0002] This invention relates to adhesive sheets.

[0003] This application claims priority to Japanese Patent Application No. 2019-041004, filed on March 6, 2019, the entire contents of which are incorporated herein by reference. Background Technology

[0004] Typically, adhesives (also known as pressure-sensitive adhesives; hereinafter the same) exist in a soft, solid (viscoelastic) state within a temperature range near room temperature and possess the property of easily adhering to substrates under pressure. Utilizing these properties, adhesives are widely used as a bonding method with good workability and high adhesive reliability in various industries, from household appliances to automobiles and office automation (OA) equipment. Representative compositions of adhesives include those containing polymers as the base polymer that exhibit rubber-like elasticity at room temperature. Patent Document 1 is cited as a relevant technical document concerning adhesive sheets.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2013-216852 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] Patent Document 1 describes an adhesive sheet having an adhesive layer with a block copolymer of a monovinyl group replacing an aromatic compound and a conjugated diene compound as the base polymer. However, the inventors have found that adhesive sheets constructed by laminating such an adhesive layer onto a fibrous sheet (e.g., a nonwoven fabric) are difficult to achieve high peel strength to the adhered material.

[0010] Therefore, the object of the present invention is to provide an adhesive sheet which is configured by laminating an adhesive layer on a fiber sheet and is capable of providing high peel strength to the adhered object.

[0011] means for solving problems

[0012] The adhesive sheet provided according to this specification comprises a fiber sheet and an adhesive layer laminated on the fiber sheet. The adhesive layer comprises 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 may comprise a tackifying resin with a softening point less than 120°C and a tackifying resin with a softening point greater than 120°C. The fiber sheet has a thickness of 15 μm to 50 μm and a bulk density of 0.25 g / cm³. 3 ~0.50g / cm 3 By using fiber sheets with the aforementioned thickness and density as the fiber sheets for laminating the adhesive layers, it is possible to achieve an adhesive sheet that exhibits high peel strength to the adhered objects.

[0013] For the aforementioned fiber sheet, a bulk density greater than 0.35 g / cm³ is preferred. 3 And less than or equal to 0.50 g / cm 3 Fiber sheets. Fiber sheets with a bulk density within the above range are suitable for achieving adhesive sheets exhibiting higher peel strength.

[0014] In some of the adhesive sheet methods disclosed herein, for the aforementioned fiber sheet, a basis weight of 15 g / m² is preferably used. 2 Above and 25g / m 2 The following fiber sheets. When using fiber sheets with a basis weight within the above range, it is possible to achieve adhesive sheets exhibiting higher peel strength.

[0015] In some other embodiments of the adhesive sheet disclosed herein, the fiber sheet described above is preferably made with a basis weight of less than 10 g / m². 2 Furthermore, the fiber sheet has a thickness of 15μm or more but less than 25μm. When using a fiber sheet that meets these basis weight and thickness requirements, it is possible to achieve an adhesive sheet that exhibits higher peel strength.

[0016] The adhesive sheet disclosed herein can preferably be implemented with a thickness that is at least four times the thickness of the aforementioned fiber sheet. An adhesive sheet whose thickness satisfies the aforementioned relationship with the fiber sheet thickness is suitable for achieving an adhesive sheet exhibiting higher peel strength.

[0017] In a preferred embodiment, the adhesive sheet exhibits a 180-degree peel strength of 40 N / 20 mm or higher against a stainless steel sheet. Adhesive sheets demonstrating such high peel strength can be satisfactorily used, for example, for joining or fixing components. Attached Figure Description

[0018] [ Figure 1 ] Figure 1 A schematic cross-sectional view illustrating the structure of an adhesive sheet according to one embodiment. Detailed Implementation

[0019] The preferred embodiments of the present invention will now be described. It should be noted that matters necessary for the implementation of the present invention, other than those specifically mentioned in this specification, can be understood by those skilled in the art based on the teachings on the implementation of the invention described in this specification and common technical knowledge at the time of application. The present invention can be implemented based on the content disclosed in this specification and common technical knowledge in the field. Furthermore, in the following drawings, components and parts that perform the same function are given the same reference numerals for description, and sometimes repeated descriptions are omitted or simplified. Additionally, the embodiments described in the drawings are schematic for the purpose of clearly illustrating the present invention and do not accurately represent the dimensions or scale of the actual product provided.

[0020] In this specification, "adhesive" as previously stated refers to a material that is a soft solid (viscoelastic) in a temperature range near room temperature and has the property of easily adhering to substrates by pressure. As defined in "CA Dahlquist, 'Adhesion: Fundamental and Practice', McLaren & Sons, (1966) p. 143", the adhesive referred to herein generally can be a material having a complex tensile modulus of elasticity. (1Hz) < 10 7 dynes / cm 2 Materials with the properties described above (typically materials that have the properties described above at 25°C).

[0021] In this specification, the “base polymer” of the adhesive refers to the main component of the rubbery polymer (a polymer that exhibits rubber elasticity in a temperature range near room temperature) contained in the adhesive, typically referring to a component that accounts for more than 50% by weight of the rubbery polymer.

[0022] In this specification, "block copolymer of monovinyl-substituted aromatic compound and conjugated diene compound" refers to a polymer having at least one segment with a monovinyl-substituted aromatic compound as the main monomer (meaning a copolymer content of more than 50% by weight; the same applies hereinafter) (hereinafter also referred to as "A segment") and at least one segment with a conjugated diene compound as the main monomer (hereinafter also referred to as "B segment"). Typically, the glass transition temperature of the A segment is higher than that of the B segment. Representative structures of the polymer include triblock copolymers with A segments (hard segments) at both ends of the B segment (soft segment) (ABA-structured triblock copolymers), and diblock copolymers containing one A segment and one B segment (AB-structured diblock copolymers), etc.

[0023] In this specification, "styrene-based block copolymer" refers to a polymer having at least one styrene block. The aforementioned styrene block refers to a segment with styrene as the main monomer. Segments that substantially contain only styrene are typical examples of styrene blocks described herein. Furthermore, "styrene-isoprene block copolymer" refers to a polymer having at least one styrene block and at least one isoprene block (a segment with isoprene as the main monomer). Representative examples of styrene-isoprene block copolymers include triblock copolymers (triblock copolymers) with styrene blocks (hard segments) at both ends of the isoprene block (soft segment), and diblock copolymers (diblock copolymers) containing one isoprene block and one styrene block. "Styrene-butadiene block copolymer" refers to a polymer having at least one styrene block and at least one butadiene block (a segment with butadiene as the main monomer).

[0024] In this specification, the "styrene content" of a styrene block copolymer refers to the weight percentage of styrene in the total weight of the block copolymer. The styrene content can be determined by NMR (nuclear magnetic resonance spectroscopy).

[0025] Furthermore, the proportion of diblock copolymers in styrene-based block copolymers (hereinafter sometimes referred to as the "diblock ratio" or "diblock proportion") can be determined by the following method: The styrene-based block copolymer is dissolved in tetrahydrofuran (THF). Four HPLC columns (two segments each, totaling four segments, manufactured by Tosoh Corporation) are connected in series. THF is used as the mobile phase, and high-performance liquid chromatography (HPLC) analysis is performed at 40°C and a flow rate of 1 mL / min. The peak area corresponding to the diblock copolymer is determined from the obtained chromatogram. Then, the diblock ratio is calculated by determining the percentage of the peak area corresponding to the diblock copolymer relative to the total peak area.

[0026] <Example of adhesive sheet structure>

[0027] The adhesive sheet disclosed herein (which may be in the form of a strip or equal length) may, for example, have the following characteristics: Figure 1 The cross-sectional structure of the double-sided adhesive sheet is schematically shown. This double-sided adhesive sheet 1 has a fiber sheet 15, a first adhesive layer 11 laminated on the first side of the fiber sheet 15, and a second adhesive layer 12 laminated on the second side of the fiber sheet 15. For example, as shown... Figure 1As shown, the double-sided adhesive sheet 1 before use (before being pasted onto the object) can be in a spiral shape, overlapping and wound with a release liner 21, the front side 21A and the back side 21B of which are both release surfaces. In this configuration of the double-sided adhesive sheet 1, the surface of the second adhesive layer 12 (the second adhesive surface 12A) is protected by the front side 21A of the release liner 21, and the surface of the first adhesive layer 11 (the first adhesive surface 11A) is protected by the back side 21B of the release liner 21. Alternatively, it can be in a configuration where the first adhesive surface 11A and the second adhesive surface 12A are each protected by two separate release liners.

[0028] The adhesive sheet disclosed herein may also be a single-sided adhesive sheet having a fiber sheet and an adhesive layer laminated thereon on its first side, and having no adhesive layer on the second side of the fiber sheet.

[0029] In the technology disclosed herein, conventional release paper or similar materials can be used as the release liner without particular limitation. For example, release liners with a release treatment layer on the surface of substrates such as plastic film or paper, or release liners containing low-adhesion materials such as fluorinated polymers (polytetrafluoroethylene, etc.) or polyolefin resins (polyethylene, polypropylene, etc.) can be used. The release treatment layer can be, for example, a layer formed by surface treatment of the substrate using release agents such as polysiloxanes, long-chain alkyl groups, fluorinated types, or molybdenum sulfide.

[0030] <Fiber Sheet>

[0031] The adhesive sheet disclosed herein has a structure obtained by laminating adhesive layers onto a fiber sheet. The fiber sheet can be made of various fibrous materials, either alone or in blends, such as woven or non-woven fabrics, knitted fabrics, or webs. Here, non-woven fabric refers to non-woven fabrics produced using conventional papermaking machines, such as Japanese paper and woodfree paper. Felt is also included in the concept of non-woven fabric. Examples of the fibrous materials constituting the fiber sheet include, in addition to natural fibers and chemical fibers (synthetic fibers) as described later, inorganic fibers such as glass fibers and carbon fibers, and metal fibers. Two or more fibrous materials of different materials can also be used together. The fiber sheet can also be understood as a supporting substrate for holding the adhesive layer.

[0032] As for the fiber sheet, a thickness of 15μm or more and 50μm or less and a bulk density of 0.25g / cm³ are used. 3 Above and 0.50 g / cm 3The following fiber sheet. By using a fiber sheet with the aforementioned thickness and bulk density as the laminated adhesive layer disclosed herein, it is possible to appropriately achieve an adhesive sheet exhibiting high peel strength to the adhered material. The reason for this effect is believed to be that by impregnating the fiber sheet with adhesive to strengthen the adhesive layer, and by having the adhesive act as a binder for the fibers constituting the fiber sheet to increase the strength of the fiber sheet, the adhesive sheet is prevented from peeling off in a cracking manner within the thickness of the fiber sheet (hereinafter also referred to as cracking peel), thereby achieving high peel strength, but this is not interpreted in a particularly limiting way. The fiber sheet has a thickness of 50 μm or less and a bulk density of 0.50 g / cm³. 3 The following conditions facilitate the penetration of the adhesive into the interior of the fiber sheet, effectively suppressing the aforementioned cracking and peeling. This is achieved by using a fiber sheet with a thickness of 15 μm or more and a bulk density of 0.25 g / cm³. 3 The above measures can prevent the strength of the fiber sheet itself from becoming too low.

[0033] In some embodiments, the thickness of the fiber sheet can be less than 50 μm, less than 40 μm, less than 30 μm, less than 25 μm, or less than 20 μm. When the thickness of the fiber sheet decreases, it is easier for the adhesive to penetrate into the interior of the fiber sheet. Furthermore, the adhesive sheet disclosed herein can also be preferably implemented by using fiber sheets with a thickness of 35 μm or more but less than 50 μm, 45 μm or more but less than 50 μm, or greater than or equal to 45 μm but less than 50 μm. By increasing the thickness of the fiber sheet within the above ranges, a balanced approach can be taken to improve the strength of the fiber sheet itself and to allow the adhesive to penetrate into the interior of the fiber sheet.

[0034] The bulk density of the fiber sheet is 0.27 g / cm³. 3 The above is appropriate, and preferably 0.30 g / cm³. 3 The above. In a preferred embodiment, a bulk density greater than 0.35 g / cm³ is preferably used. 3 And less than or equal to 0.50 g / cm 3 The fiber sheet has a bulk density greater than 0.35 g / cm³. 3 It can prevent the fiber sheet from being easily crushed in the thickness direction during the production of adhesive sheets, which would make it difficult for the adhesive to penetrate. It can help to achieve adhesive sheets where the adhesive can penetrate well into the fiber sheet.

[0035] The basis weight (weight per unit area) of the fiber sheet is typically 3.8 g / m². 2 Above and 25g / m 2 The following is preferred, for example, 4.5 g / m 2 Above and 25g / m 2The adhesive sheet disclosed herein can preferably be implemented using fiber sheets with a basis weight within the above-described range.

[0036] In a preferred embodiment of the adhesive sheet disclosed herein, the fiber sheet is preferably made of a thickness of 15 μm to 50 μm (preferably 30 μm to 50 μm, for example 45 μm to 50 μm) and a bulk density of 0.25 g / cm³. 3 ~0.50g / cm 3 (Preferred size is greater than 0.35 g / cm³) 3 And less than or equal to 0.50 g / cm 3 More preferably 0.40 g / cm³ 3 ~0.50g / cm 3 For example, 0.45 g / cm³ 3 ~0.50g / cm 3 ), with a basis weight of 15g / m 2 Above and 25g / m 2 The following (preferably 18g / m) 2 Above and 25g / m 2 For example, 21g / m 2 Above and 25g / m 2 The fiber sheet (hereinafter referred to as the fiber sheet). When the adhesive layer described later is laminated onto such a fiber sheet (e.g., nonwoven fabric), an adhesive sheet exhibiting high peel strength to the adhered object can be appropriately achieved. In this manner, it is appropriate for the thickness of the adhesive sheet to be about 4.0 times to about 8.0 times the thickness of the fiber sheet, preferably about 4.5 times to about 6.5 times.

[0037] In another preferred embodiment of the adhesive sheet disclosed herein, the fiber sheet is preferably made of a thickness of 15 μm to 50 μm (preferably 15 μm to 25 μm, for example 15 μm to 20 μm) and a bulk density of 0.25 g / cm³. 3 ~0.50g / cm 3 (Preferred size is greater than 0.35 g / cm³) 3 And less than or equal to 0.50 g / cm 3 More preferably greater than 0.35 g / cm 3 And less than or equal to 0.40 g / cm 3 (Basis weight less than 10g / m) 2 (typically greater than or equal to 4.5 g / m 2 And less than 10g / m 2 Preferably, it should be greater than or equal to 5.0 g / m 2 And less than 10g / m 2 For example, greater than or equal to 5.0 g / m 2 And less than 8.00 g / m 2The adhesive sheet (described later) is a fiber sheet. When the adhesive layer is laminated onto such a fiber sheet (e.g., nonwoven fabric), an adhesive sheet exhibiting high peel strength to the adhered object can be appropriately achieved. In this manner, it is appropriate to set the thickness of the adhesive sheet to about 10 to about 30 times the thickness of the fiber sheet, preferably about 12 to about 25 times, and more preferably about 15 to about 20 times.

[0038] In some of the adhesive sheet methods disclosed herein, nonwoven fabric can preferably be used as the aforementioned fiber sheet. For example, nonwoven fabrics can be made of natural fibers such as wood pulp, hemp pulp, cotton, hemp (e.g., Manila hemp), wool, and silk; nonwoven fabrics made of polyester fibers such as polyethylene terephthalate (PET) fibers, rayon, vinylon, acetate fibers, polyvinyl alcohol (PVA) fibers, polyamide fibers, polyolefin fibers, and polyurethane fibers (synthetic fibers); and nonwoven fabrics made of two or more fibers of different materials; etc. From the viewpoint of adhesive permeability and strength, nonwoven fabrics using wood pulp, hemp pulp (e.g., hemp pulp made from Manila hemp), wool, or PET fibers as constituent fibers are preferred.

[0039] In addition to the fibrous materials described above, fiber sheets (e.g., nonwoven fabrics) may also typically contain resin components such as starch (e.g., cationic starch), polyacrylamide, viscose, polyvinyl alcohol, urea-formaldehyde resin, melamine-formaldehyde resin, and polyamide-polyamine-epoxychloropropane in a non-fibrous form. These resin components can function as paper strength reinforcing agents for the nonwoven fabric. By using the resin components as needed, the strength of the fiber sheet and the penetration of the adhesive into the fiber sheet can be adjusted. The fiber sheets in the disclosed technology may also contain, as needed, retention aids, filtration agents, viscosity modifiers, dispersants, and other additives conventional in the field related to the manufacture of fiber sheets (e.g., nonwoven fabrics).

[0040] <Adhesive layer>

[0041] (Basic Polymer)

[0042] The adhesive layer disclosed herein contains a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound as the base polymer. The aforementioned monovinyl-substituted aromatic compound refers to a compound having a vinyl functional group bonded to an aromatic ring. Representative examples of the aromatic ring include benzene rings (which may be benzene rings substituted with functional groups not having vinyl groups (e.g., alkyl groups)). Specific examples of the aforementioned monovinyl-substituted aromatic compound include styrene, α-methylstyrene, vinyltoluene, vinylxylene, etc. Specific examples of the aforementioned conjugated diene compound include 1,3-butadiene, isoprene, etc. Such block copolymers can be used alone or in combination of two or more in the base polymer.

[0043] In the block copolymer described above, the copolymerization ratio of the A segment (hard segment) of the monovinyl substituted aromatic compound (two or more may be used in combination) is preferably 70% by weight or more (more preferably 90% by weight or more, and substantially 100% by weight). In the B segment (soft segment) of the block copolymer described above, the copolymerization ratio of the conjugated diene compound (two or more may be used in combination) is preferably 70% by weight or more (more preferably 90% by weight or more, and substantially 100% by weight). Using the block copolymer, higher performance adhesive sheets can be achieved.

[0044] The block copolymers described above can be diblock, triblock, radial, or mixtures thereof. In triblock and radial copolymers, it is preferable to have A-segments (e.g., styrene blocks) at the ends of the polymer chains. This is because A-segments at the ends of the polymer chains readily aggregate to form domains, thereby creating a pseudo-crosslinked structure and improving the cohesiveness of the adhesive.

[0045] As for the block copolymers in the technology disclosed herein, from the viewpoint of adhesive strength (peel strength) to the adherends, block copolymers with a diblock ratio of 30% by weight or more (more preferably 40% by weight or more, further preferably 50% by weight or more, particularly preferably 60% by weight or more, and typically 65% ​​by weight or more) are preferred. From the viewpoint of peel strength, block copolymers with a diblock ratio of 70% by weight or more are particularly preferred. Furthermore, from the viewpoint of cohesiveness, block copolymers with a diblock ratio of 90% by weight or less (more preferably 85% by weight or less, for example, 80% by weight or less) are preferred. For example, block copolymers with a diblock ratio of 60% to 85% by weight are preferred, and block copolymers with a diblock ratio of 70% to 85% by weight (for example, 70% to 80% by weight) are more preferred.

[0046] In a preferred embodiment of the disclosed technology, the base polymer is a styrene-based block copolymer. For example, it is preferred that the base polymer comprises at least one of a styrene-isoprene block copolymer and a styrene-butadiene block copolymer. Among the styrene-based block copolymers contained in the adhesive, it is preferred that the proportion of the styrene-isoprene block copolymer is 70% by weight or more, or the proportion of the styrene-butadiene block copolymer is 70% by weight or more, or the combined proportion of the styrene-isoprene block copolymer and the styrene-butadiene block copolymer is 70% by weight or more. In a preferred embodiment, the styrene-based block copolymer is substantially all (e.g., 95% to 100% by weight) of the styrene-isoprene block copolymer. In another preferred embodiment, the styrene-based block copolymer is substantially all (e.g., 95% to 100% by weight) of the styrene-butadiene block copolymer. With such a composition, the effects of applying the disclosed technology can be better realized.

[0047] The aforementioned styrene-based block copolymers can be diblock, triblock, radial, or mixtures thereof. In triblock and radial copolymers, styrene blocks are preferably disposed at the ends of the polymer chains. This is because styrene blocks disposed at the ends of the polymer chains readily aggregate to form styrene domains, thereby creating a pseudo-crosslinked structure and improving the cohesiveness of the adhesive. As for the styrene-based block copolymers used in the art disclosed herein, from the viewpoint of adhesive strength (peel strength) to the adherends, styrene-based block copolymers with a diblock ratio of 30% by weight or more (more preferably 40% by weight or more, further preferably 50% by weight or more, particularly preferably 60% by weight or more, typically 65% ​​by weight or more) are preferred. Styrene-based block copolymers with a diblock ratio of 70% by weight or more (e.g., 75% by weight or more) are also acceptable. Furthermore, from the viewpoint of cohesiveness, styrene-based block copolymers with a diblock ratio of 90% by weight or less (more preferably 85% by weight or less, e.g., 80% by weight or less) are preferred. From the viewpoint of balancing cohesiveness and low-temperature resilience when using the technology disclosed herein, a styrene block copolymer with a diblock ratio of 60% to 85% by weight is preferred, and a styrene block copolymer with a diblock ratio of 70% to 85% by weight (e.g., 70% to 80% by weight) is more preferred.

[0048] The styrene content of the aforementioned styrene-based block copolymers can be, for example, from 5% to 40% by weight. From the viewpoint of cohesiveness, styrene-based block copolymers with a styrene content of 10% by weight or more (more preferably greater than 10% by weight, for example, 12% by weight or more) are generally preferred. Furthermore, 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 particularly preferably 20% by weight or less (typically less than 20% by weight, for example, 18% by weight or less). From the viewpoint of better utilizing the technology disclosed herein, styrene-based block copolymers with a styrene content of 12% by weight or more and less than 20% by weight are preferred.

[0049] (Tackifying resin)

[0050] In addition to the base polymer described above, the adhesive layer disclosed herein also includes a tackifying resin. Preferably, the adhesive layer contains a tackifying resin with a softening point of less than 120°C and a tackifying resin with a softening point of 120°C or higher as the tackifying resin.

[0051] The softening point of the tackifying resin described herein is defined as the value determined based on the softening point test method (ring and ring method) specified in JIS K5902 and JIS K2207. Specifically, the sample is rapidly melted at the lowest possible temperature and carefully filled into a ring placed on a flat metal plate without forming air bubbles. After cooling, the raised portion is cut off from the plane containing the ring from the upper end using a slightly heated knife. Next, the support (ring stage) is placed in a glass container (heating bath) with a diameter of 85 mm or more and a height of 127 mm or more, and glycerol is poured in to a depth of 90 mm or more. Then, a steel ball (9.5 mm in diameter and weighing 3.5 g) and the ring filled with the sample are immersed in the glycerol without touching each other, and the temperature of the glycerol is maintained at 20°C. Maintain 5°C for 15 minutes. Next, place the steel ball on the center of the sample surface in the ring and position it on the support. Then, maintaining a distance of 50 mm from the top of the ring to the glycerin surface, place a thermometer with the center of the thermometer's mercury bulb at the same height as the center of the ring, and heat the container. The flame of the Bunsen burner used for heating should be in contact with the center of the bottom and the middle of the edge of the container for uniform heating. It should be noted that the bath temperature rise rate after reaching 40°C from the start of heating must be 5.0°C per minute. 0.5℃. The temperature at which the sample gradually softens, flows down the ring, and finally contacts the base plate is recorded as the softening point. If two or more softening points are measured simultaneously, their average value is used.

[0052] Tackifying resins with a softening point less than 120℃ and tackifying resins with a softening point above 120℃ can be selected independently from various known tackifying resins such as petroleum resins, styrene resins, coumarone-indene resins, terpene resins, modified terpene resins, rosin resins, rosin derivative resins, and ketone resins, and tackifying resins with a softening point that meets the requirements.

[0053] Examples of petroleum resins include aliphatic (C5) petroleum resins, aromatic (C9) petroleum resins, aliphatic / aromatic copolymers (C5 / C9) petroleum resins, and their hydrides (e.g., alicyclic petroleum resins obtained by hydrogenating aromatic petroleum resins).

[0054] Examples of styrene-based resins include styrene-based resins with styrene homopolymer as the main component, styrene-based resins with α-methylstyrene homopolymer as the main component, styrene-based resins with vinyltoluene homopolymer as the main component, and styrene-based resins with copolymers containing two or more of styrene, α-methylstyrene, and vinyltoluene as the main component (e.g., α-methylstyrene / styrene copolymer resin with α-methylstyrene / styrene copolymer as the main component).

[0055] As a coumarone-indene resin, a resin containing coumarone and indene as monomeric components constituting the resin backbone (main chain) can be used. Other monomeric components that may be contained in the resin backbone besides coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0056] Examples of terpene resins include α-pinene polymers, β-pinene polymers, and terpinene polymers. Examples of modified terpene resins include substances obtained by modifying the above-mentioned terpene resins (phenol modification, styrene modification, hydrogenation modification, hydrocarbon modification, etc.). Specifically, examples include terpene phenol resins, styrene-modified terpene resins, and hydrogenated terpene resins.

[0057] The term "terpene phenol resin" as used above refers to a polymer containing terpene residues and phenol residues. It encompasses both copolymers of terpenes and phenolic compounds (terpene-phenol copolymer resins) and substances obtained by modifying homopolymers or copolymers of terpenes (terpene resins, typically unmodified terpene resins) with phenol (phenol-modified terpene resins). Preferred examples of terpenes constituting the aforementioned terpene phenol resin include monoterpenes such as α-pinene, β-pinene, and limonene (including d-form, l-form, and d / l-form (terpinene)).

[0058] Specific examples of rosin resins include: unmodified rosin (raw rosin), such as resin rosin, wood rosin, and oil rosin; modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, and other chemically modified rosin) obtained by modifying these unmodified rosin through hydrogenation, disproportionation, polymerization, etc.; etc. Additionally, examples of rosin derivative resins include: rosin esters, such as substances obtained by esterifying unmodified rosin with alcohols (i.e., rosin esters), substances obtained by esterifying modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) with alcohols (i.e., modified rosin esters); unsaturated fatty acid-modified rosin, obtained by modifying unmodified rosin or modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) with unsaturated fatty acids; and rosin esters obtained by modifying rosin with unsaturated fatty acids. Unsaturated fatty acid modified rosin esters; rosin alcohols obtained by reducing the carboxyl groups in unmodified rosin, modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.), unsaturated fatty acid modified rosin, or unsaturated fatty acid modified rosin esters; metal salts of rosin (especially rosin esters), including unmodified rosin, modified rosin, and various rosin derivatives; rosin phenol resins obtained by adding phenols to rosin (unmodified rosin, modified rosin, various rosin derivatives, etc.) using an acid catalyst and then thermally polymerizing them; etc.

[0059] As a preferred embodiment, the adhesive layer may contain one or more terpene phenolic resins. For example, the proportion of terpene phenolic resin in the total amount of tackifying resin may be 15% by weight or more, preferably 25% by weight or more, 30% by weight or more, or 35% by weight or more. In some embodiments, the above proportion may be 45% by weight or more, or 55% by weight or more. Furthermore, the proportion of terpene phenolic resin in the total amount of tackifying resin may be 90% by weight or less, preferably 80% by weight or less, 70% by weight or less, 60% by weight or less, or 50% by weight or less.

[0060] When the adhesive layer contains terpene phenol resin as a tackifying resin, it is appropriate for the content of terpene phenol resin to be 5 parts by weight or more relative to 100 parts by weight of the base polymer, preferably 10 parts by weight or more (e.g., more than 10 parts by weight), and more preferably 15 parts by weight or more. Furthermore, it is appropriate for the content of terpene phenol resin in the adhesive layer to be 70 parts by weight or less relative to 100 parts by weight of the base polymer, preferably 60 parts by weight or less, and more preferably 50 parts by weight or less.

[0061] (Tackifying resin T) H )

[0062] In the disclosed technology, the aforementioned tackifying resin preferably contains a tackifying resin with a softening point of 120°C or higher (hereinafter, sometimes referred to as "tackifying resin T"). H From the perspective of resilience and high-temperature cohesion, tackifying resin T... H The softening point is preferably 125°C or higher, more preferably 130°C or higher, and even more preferably 135°C or higher (e.g., 140°C or higher). Furthermore, from the viewpoint of peel strength of the adhered materials, the tackifying resin T... H A softening point of 200°C or less is generally suitable, preferably 180°C or less, and more preferably 170°C or less (e.g., 160°C or less).

[0063] As a tackifying resin T H Alternatively, one or more of the following can be used: petroleum resin, styrene resin, coumarone-indene resin, modified terpene resin, rosin resin, rosin derivative resin, ketone resin, etc. Among them, terpene phenol resin, rosin phenol resin, polymerized rosin, and esterified polymerized rosin are preferred.

[0064] As a preferred approach, one or more terpene phenolic resins can be used as the tackifying resin T. H The softening point of the terpene phenol resin used can be, for example, 125°C or higher, and from the viewpoint of heat resistance and cohesiveness, preferably 130°C or higher, preferably 135°C or higher, or preferably 140°C or higher. The softening point of the aforementioned terpene phenol resin can be, for example, 200°C or lower, and from the viewpoint of adhesion and compatibility, preferably 180°C or lower, preferably 170°C or lower, or preferably 160°C or lower.

[0065] In some methods, tackifying resin T H At least 25% by weight (preferably 30% by weight or more, more preferably 50% by weight or more, for example 60% by weight or more) of the tackifying resin T can be set as a terpene phenol resin. Additionally, the tackifying resin T H The amount of terpene phenol resin in the resin can be, for example, about 85% by weight or less, or about 75% by weight or less. Alternatively, in some embodiments, the tackifying resin T... H The amount of terpene phenol resin in the resin can be, for example, 70% or more by weight, 80% or more by weight, or 90% or more by weight. Tackifying resin T H It can be substantially all (e.g., 95% to 100% by weight, further 99% to 100% by weight) of terpene phenol resin.

[0066] The technology disclosed herein can preferably use a tackifying resin T containing a hydroxyl value of 80 mg KOH / g or more (e.g., 90 mg KOH / g or more). H As a tackifying resin T HThis is implemented in this way. Below, sometimes tackifying resins T with a hydroxyl value of 80 mg KOH / g or higher (e.g., 90 mg KOH / g or higher) are used. H Recorded as "Tackifying Resin T" HO1 Tackifying resin T HO1 The hydroxyl value is typically below 200 mg KOH / g, preferably below 180 mg KOH / g, and for example below 160 mg KOH / g. This is achieved using a tackifying resin T... HO1 Adhesives can be used to achieve higher performance bonded sheets. For example, bonded sheets can be made that balance cohesion and other properties (such as low-temperature resilience) at a higher level.

[0067] Here, the hydroxyl value of the tackifying resin used in this specification can be determined by potentiometric titration as specified in JIS K0070:1992. The specific determination method is as follows.

[0068] [Method for determining hydroxyl value]

[0069] 1. Reagents

[0070] (1) As an acetylation reagent, a reagent obtained by means of taking about 12.5 g (about 11.8 mL) of acetic anhydride, adding pyridine to it to make a total volume of 50 mL, and stirring thoroughly; or, a reagent obtained by means of taking about 25 g (about 23.5 mL) of acetic anhydride, adding pyridine to it to make a total volume of 100 mL, and stirring thoroughly.

[0071] (2) As a reagent for determination, a 0.5 mol / L potassium hydroxide ethanol solution is used.

[0072] (3) In addition, prepare toluene, pyridine, ethanol and distilled water.

[0073] 2. Operation

[0074] (1) Accurately weigh about 2g of the sample into a flat-bottomed flask, add 5mL of acetylation reagent and 10mL of pyridine, and install an air cooling tube.

[0075] (2) Heat the above flask in a bath at 100°C for 70 minutes, then allow it to cool naturally. Add 35 mL of toluene as a solvent from the top of the cooling tube and stir. Then add 1 mL of distilled water and stir to decompose the acetic anhydride. To ensure complete decomposition, heat the flask again in the bath for 10 minutes and allow it to cool naturally.

[0076] (3) Clean the cooling tube with 5 mL of ethanol and remove it. Then, add 50 mL of pyridine as a solvent and stir.

[0077] (4) Using a full-volume pipette, add 25 mL of 0.5 mol / L potassium hydroxide ethanol solution.

[0078] (5) Perform potentiometric titration using 0.5 mol / L potassium hydroxide ethanol solution. Take the inflection point of the obtained titration curve as the endpoint.

[0079] (6) In the blank test, the above (1) to (5) are carried out without adding a sample.

[0080] 3. Calculation

[0081] The hydroxyl value is calculated using the following formula.

[0082] Hydroxyl value (mgKOH / g) = [(BC) × f × 28.05] / S + D

[0083] Here, B: The volume (mL) of 0.5 mol / L potassium hydroxide ethanol solution used in the blank test. C: Volume (mL) of 0.5 mol / L potassium hydroxide ethanol solution used in the sample. f: coefficient of 0.5 mol / L potassium hydroxide ethanol solution S: Weight of the sample (g) D: Acid value 28.05: Half of the molecular weight of potassium hydroxide, which is 56.11.

[0084] As a tackifying resin T HO1 Specifically, tackifying resins with a hydroxyl value of a specified value or higher can be used alone or in appropriate combinations among the various tackifying resins described above. In a preferred embodiment, at least a terpene phenol resin is used as the tackifying resin T. HO1 For terpene phenol resins, the hydroxyl value can be arbitrarily controlled by the copolymerization ratio of phenols, making them preferred. Terpene phenol resins are used in tackifying resins T... HO1 The proportion of the tackifying resin T in the product is approximately 50% by weight or more, preferably 80% by weight or more, and more preferably 90% by weight or more. HO1 It can be substantially all (e.g., 95% to 100% by weight, further 99% to 100% by weight) of terpene phenol resin.

[0085] The technology disclosed herein is for using a tackifying resin T HO1 In the case of implementing the adhesive layer method, the tackifying resin T HO1There is no particular limitation on the proportion of the total tackifying resin. The above proportion may be, for example, 10% by weight or more, preferably 15% by weight or more, more preferably 20% by weight or more, or 25% by weight or more. In addition, in some embodiments, from the viewpoint of adhesive strength, compatibility, etc., the above proportion may be, for example, 70% by weight or less, 60% by weight or less, 50% by weight or less, or 40% by weight or less.

[0086] The disclosed technology preferably uses a tackifying resin T with a hydroxyl value greater than or equal to 40 mg KOH / g and less than 80 mg KOH / g in the aforementioned adhesive layer. H This is implemented in a manner described below. Sometimes, tackifying resins with a hydroxyl value greater than or equal to 40 mg KOH / g and less than 80 mg KOH / g are used. H Recorded as "Tackifying Resin T" HO2 Tackifying resin T HO2 The hydroxyl value can be above 45 mg KOH / g or above 50 mg KOH / g. Additionally, the tackifying resin T... HO2 The hydroxyl value can be below 75 mg KOH / g or below 70 mg KOH / g.

[0087] As a tackifying resin T HO2 Specifically, the tackifying resins that meet the specified hydroxyl value can be used alone or in appropriate combinations among the various tackifying resins described above. In a preferred embodiment, tackifying resin T... HO2 At least terpene phenol resin should be used. Terpene phenol resin is used in tackifying resins T. HO2 The proportion of the tackifying resin T in the product is approximately 50% by weight or more, preferably 80% by weight or more, and more preferably 90% by weight or more. HO2 It can be substantially all (e.g., 95% to 100% by weight, further 99% to 100% by weight) of terpene phenol resin.

[0088] The technology disclosed herein is used in the application of a tackifying resin T HO2 In the case of implementing the adhesive layer method, the tackifying resin T HO2 There is no particular limitation on the proportion of the total tackifying resin. The above proportion may be, for example, 10% by weight or more, preferably 15% by weight or more, more preferably 20% by weight or more, or 25% by weight or more. In addition, in some embodiments, from the viewpoint of adhesive cohesiveness, the above proportion may be, for example, 70% by weight or less, 60% by weight or less, 50% by weight or less, or 40% by weight or less.

[0089] In some preferred embodiments, tackifying resin T can be used in combination. HO1 and tackifying resin T HO2In the aforementioned manner, T HO1 With T HO2 The relationship of usage amount can be, for example, made so that the weight ratio (T) HO1 :T HO2 The ratio (T) is set within the range of 1:5 to 5:1 to achieve the desired weight ratio (T). HO1 :T HO2 Setting it within the range of 1:3 to 3:1 (e.g., 1:2 to 2:1) is appropriate. As a preferred method, T can be listed as... HO1 T HO2 Both are made using terpene phenol resins.

[0090] In one aspect of the disclosed technology, the aforementioned tackifying resin T H It may contain tackifying resin T with an aromatic ring and a hydroxyl value of less than 40 mg KOH / g. H The following section sometimes refers to tackifying resin T with an aromatic ring and a hydroxyl value of less than 40 mg KOH / g. H Recorded as "Tackifying Resin T" HR1 Tackifying resin T HR1 The hydroxyl value is preferably less than 30 mg KOH / g, more preferably less than 10 mg KOH / g, and can be less than 5 mg KOH / g or less than 3 mg KOH / g. In some methods, it is preferable to use a tackifying resin T with a hydroxyl value of less than 1 mg KOH / g or with no detectable hydroxyl groups. HR1 .

[0091] Examples of tackifying resins containing aromatic rings include the aforementioned aromatic petroleum resins, aliphatic / aromatic copolymer petroleum resins, styrene resins, coumarone-indene resins, styrene-modified terpene resins, phenol-modified terpene resins, and rosinol resins. Among these, a tackifying resin with a softening point of 120°C or higher (preferably 130°C or higher, for example 135°C or higher) and satisfying any of the aforementioned hydroxyl values ​​can be used as tackifying resin T. HR1 Tickling resin T is a preferred tackifying resin. HR1 Examples include aromatic petroleum resins and styrene resins (e.g., α-methylstyrene / styrene copolymer resins). It should be noted that the technology disclosed herein can also be used with an adhesive layer that is substantially free of tackifying resin T. HR1 This will be implemented in this way.

[0092] In another embodiment of the adhesive disclosed herein, the aforementioned tackifying resin T H It may contain tackifying resin T with an aromatic ring and substantially free of isoprene units, terpene skeletons, and rosin skeletons. H Hereinafter, such tackifying resin T is sometimes referred to as... H Recorded as "Tackifying Resin T" HR2"Here, tackifying resin T..." HR2 Essentially, the absence of isoprene units, terpene skeletons, and rosin skeletons means that these structural parts (i.e., isoprene units, terpene skeletons, and rosin skeletons) are absent in the tackifying resin T. HR2 The total proportion of these components is less than 10% by weight (more preferably less than 8% by weight, even more preferably less than 5% by weight, for example less than 3% by weight). The above proportion can be 0% by weight. It should be noted that the isoprene unit, terpene skeleton, and rosin skeleton in the tackifying resin T... HR2 The proportion of it can be determined, for example, by NMR (nuclear magnetic resonance spectroscopy).

[0093] Examples of tackifying resins that have aromatic rings and substantially do not contain isoprene units, terpene skeletons, or rosin skeletons include the aforementioned aromatic petroleum resins, aliphatic / aromatic copolymer petroleum resins, styrene resins, and coumarone-indene resins. Among these, a tackifying resin with a softening point of 120°C or higher (preferably 130°C or higher, for example, 135°C or higher) can be used as the tackifying resin T. HR2 Among them, T is a preferred tackifying resin. HR2 Examples include aromatic petroleum resins and styrene resins (e.g., α-methylstyrene / styrene copolymer resins). As a tackifying resin, T... HR2 Specifically, a tackifying resin with a hydroxyl value of less than 40 mg KOH / g (more preferably less than 30 mg KOH / g, even more preferably less than 10 mg KOH / g, for example less than 5 mg KOH / g or less than 3 mg KOH / g) is preferred. For example, a tackifying resin T with a hydroxyl value of less than 1 mg KOH / g or with no detectable hydroxyl groups is preferred. HR2 Therefore, as the tackifying resin T in the technology disclosed herein... HR2 In this regard, it is preferable to use a tackifying resin T. HR1 The tackifying resin. Similarly, as the tackifying resin T in the technology disclosed herein... HR1 In this regard, it is preferable to use a tackifying resin T. HR2 The tackifying resin. It should be noted that the technology disclosed herein can also be used with an adhesive layer that substantially does not contain the tackifying resin. HR2 This will be implemented in this way.

[0094] From the perspective of improving cohesiveness, the tackifying resin T relative to 100 parts by weight of the base polymer... H Setting the total amount (i.e., the total amount of tackifying resin with a softening point of 120°C or higher) to 20 parts by weight or more is appropriate, preferably 30 parts by weight or more, and more preferably 35 parts by weight or more. The technique disclosed herein preferably uses 100 parts by weight of tackifying resin T relative to the base polymer. HThe method is implemented with a total amount of 40 parts by weight or more (e.g., 50 parts by weight or more). Additionally, the tackifying resin T is present in 100 parts by weight relative to the base polymer. H The content can be set to 100 parts by weight or less, for example. From the point of view of adhesion and compatibility, it is appropriate to set it to 90 parts by weight or less, and preferably to 80 parts by weight or less.

[0095] From the perspective of improving cohesion, tackifying resin T H Setting the proportion of the tackifying resin in the total amount to about 20% by weight or more is appropriate, preferably 30% by weight or more, more preferably 40% by weight or more, and can be 50% by weight or more, or 60% by weight or more. In addition, the above proportion can be set to 95% by weight or less, for example. From the viewpoint of improving adhesion, setting it to 85% by weight or less is advantageous. It can be 75% by weight or less, 70% by weight or less, or 65% by weight or less.

[0096] (Tackifying resin T) L )

[0097] In the disclosed technology, the aforementioned tackifying resin preferably includes tackifying resin T. H In addition, it also contains a tackifying resin with a softening point of less than 120°C (hereinafter, sometimes referred to as "tackifying resin T"). L (). By combining the use of tackifying resin T H and tackifying resin T L It can achieve a balanced combination of adhesion and cohesion. Therefore, it is possible to appropriately produce adhesive sheets exhibiting high peel strength.

[0098] For tackifying resin T L There is no particular limitation on the lower limit of the softening point. Generally, tackifying resins with a softening point of 40°C or higher (typically 60°C or higher) are preferred. From the viewpoint of balancing adhesion and cohesion to a high degree, tackifying resins with a softening point of 80°C or higher (more preferably 100°C or higher) and lower than 120°C are generally preferred. L Preferably, a tackifying resin T with a softening point greater than or equal to 110°C and less than 120°C is used. L .

[0099] As a tackifying resin T L In general, tackifying resins with a softening point of less than 120°C can be used alone or in appropriate combinations among the various tackifying resins mentioned above (petroleum resins, styrene resins, coumarone-indene resins, terpene resins, modified terpene resins, rosin resins, rosin derivative resins, ketone resins, etc.).

[0100] The disclosed technology preferably uses at least one of petroleum resin and terpene resin as the tackifying resin T in the above-mentioned adhesive. L This is implemented in a manner similar to that of tackifying resin T. L The main component (i.e., the proportion of tackifying resin T) L The components (more than 50% by weight) can preferably be composed of petroleum resin, terpene resin, or a combination of petroleum resin and terpene resin. From the viewpoint of adhesion and compatibility, tackifying resin T is preferred. L The main component is a terpene resin (e.g., β-pinene polymer). Tackifying resin T L It can be substantially all (e.g., more than 95% by mass) terpene resin.

[0101] From the perspective of improving cohesiveness, the tackifying resin T relative to 100 parts by weight of the base polymer... L The total amount (i.e., the total amount of tackifying resin with a softening point less than 120°C) is appropriately set to 50 parts by weight or less, preferably 40 parts by weight or less, and can be 35 parts by weight or less. Additionally, the tackifying resin T100 parts by weight relative to the base polymer... L The content can be, for example, 5 parts by weight or more. From the viewpoint of improving adhesion and penetration into the fiber sheet, it is preferred to set it to 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, or 25 parts by weight or more.

[0102] In the disclosed technology, there is no particular limitation on the total amount of tackifying resin relative to 100 parts by weight of the base polymer. From the viewpoint of balancing adhesion and cohesion, it is generally appropriate for the total amount of tackifying resin to be 20 parts by weight or more, preferably 30 parts by weight or more, and more preferably 40 parts by weight or more (e.g., 50 parts by weight or more). Furthermore, from the viewpoint of low-temperature properties (e.g., low-temperature peel strength), it is generally appropriate for the content of tackifying resin relative to 100 parts by weight of the base polymer to be 200 parts by weight or less, preferably 150 parts by weight or less, and more preferably 120 parts by weight or less (e.g., 100 parts by weight or less). It should be noted that the total amount of tackifying resin can be Ttackifying resin. H Total amount and tackifying resin T L The total amount of measurement.

[0103] (Isocyanate compounds)

[0104] The adhesive compositions disclosed herein may further contain isocyanate compounds. Isocyanate compounds can improve the cohesiveness of the adhesive and contribute to achieving adhesive sheets exhibiting higher peel strength. As for the isocyanate compound, polyfunctional isocyanates (compounds having an average of two or more isocyanate groups per molecule, including compounds having an isocyanurate structure) are preferably used. As for the polyfunctional isocyanate, one or more isocyanate compounds (polyisocyanates) selected from various isocyanate compounds (polyisocyanates) having two or more isocyanate groups per molecule can be used. Examples of the polyfunctional isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, etc.

[0105] Specific examples of aliphatic polyisocyanates include: 1,2-ethylene diisocyanate; tetramethylene diisocyanates such as 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate, and 1,4-tetramethylene diisocyanate; hexamethylene diisocyanates such as 1,2-hexamethylene diisocyanate, 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 2,5-hexamethylene diisocyanate; 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and lysine diisocyanate.

[0106] Specific examples of alicyclic polyisocyanates include: isophorone diisocyanate; cyclohexyl diisocyanates such as 1,2-cyclohexyl diisocyanate, 1,3-cyclohexyl diisocyanate, and 1,4-cyclohexyl diisocyanate; cyclopentyl diisocyanates such as 1,2-cyclopentyl diisocyanate and 1,3-cyclopentyl diisocyanate; hydrogenated diphenylmethylene diisocyanate, hydrogenated toluene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0107] Specific examples of aromatic polyisocyanates include: 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrobiphenyl-4,4'-diisocyanate, and 2,2'-diphenylpropane-4,4'-diisocyanate. '-Diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, terephthalene diisocyanate, 1,4-naphthalene diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, phenylenediamine-1,4-diisocyanate, phenylenediamine-1,3-diisocyanate, etc.

[0108] Preferred isocyanate compounds include polyfunctional isocyanates having an average of three or more isocyanate groups per molecule. The trifunctional or higher isocyanates can be polymers (typically dimers or trimers) of difunctional or trifunctional or higher isocyanates, derivatives (e.g., addition reaction products of polyols with two or more molecules of polyfunctional isocyanates), polymers, etc. Examples include: dimers or trimers of diphenylmethane diisocyanate, isocyanurate forms of hexamethylene diisocyanate (trimeric adducts of isocyanurate structures), reaction products of trimethylolpropane and toluene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, polymethylene polyphenyl isocyanates, polyether polyisocyanates, polyester polyisocyanates, and other polyfunctional isocyanates. Commercially available examples of the aforementioned polyfunctional isocyanates include: "DURANATE TPA-100" manufactured by Asahi Kasei Chemicals Co., Ltd., "Coronate L" manufactured by Tosoh Co., Ltd., "Coronate HL" manufactured by Tosoh Co., Ltd., "Coronate HK" manufactured by Tosoh Co., Ltd., "Coronate HX" manufactured by Tosoh Co., Ltd., and "Coronate 2096" manufactured by Tosoh Co., Ltd.

[0109] When using isocyanate compounds, there are no particular limitations on their usage; for example, it can be set to greater than 0 parts by weight and less than or equal to 10 parts by weight relative to 100 parts by weight of the base polymer (typically 0.01 parts by weight to 10 parts by weight). Generally, it is appropriate to set the amount of isocyanate compound used relative to 100 parts by weight of the base polymer to be 0.1 parts by weight to 10 parts by weight, preferably 0.1 parts by weight to 5 parts by weight (typically 0.3 parts by weight to 3 parts by weight, for example 0.5 parts by weight to 1 part by weight). By using isocyanate compounds within the aforementioned range, adhesive sheets with excellent performance balance can be achieved, in particular.

[0110] (Other ingredients)

[0111] To the extent that it does not significantly impair the effects of the present invention, the adhesive layer in the disclosed technology may, as needed, contain one or more rubber-like polymers other than the base polymer. The rubber-like polymer may be various polymers known in the adhesive field, such as rubbers, acrylics, polyesters, urethanes, polyethers, polysiloxanes, polyamides, and fluorinated polymers. The disclosed technology may preferably be implemented in a manner where the adhesive layer substantially does not contain rubber-like polymers other than the base polymer (e.g., in a manner where the content is 0 to 1 part by weight relative to 100 parts by weight of the base polymer).

[0112] The adhesive layer in the disclosed technology may contain, as needed, various additives conventional in the field of adhesives, such as leveling agents, crosslinking agents, crosslinking aids, plasticizers, softeners, fillers, colorants (pigments, dyes, etc.), antistatic agents, antioxidants, UV absorbers, antioxidants, and light stabilizers. These various additives can be obtained using existing, known additives through conventional methods. The adhesive disclosed herein is preferably implemented in a manner that substantially does not contain liquid rubber such as polybutene (e.g., the content is less than 1 part by weight per 100 parts by weight of the base polymer, or can be 0 parts by weight).

[0113] In a preferred embodiment, the adhesive layer may consist of a composition in which the combined amount of the base polymer and the tackifying resin accounts for more than 90% by weight of the total weight of the adhesive (i.e., the weight of the adhesive layer constituted by the adhesive). For example, it is preferable to use a composition in which the combined amount of the base polymer and the tackifying resin is 90% to 99.8% by weight (typically, for example, 95% to 99.5% by weight) of the total weight of the adhesive.

[0114] In another preferred embodiment, the adhesive composition described above may be substantially free of chelating compounds. Here, the chelating compound refers, for example, to a chelating compound between an oxide of an alkaline earth metal and a resin (alkylphenol resin, etc.) having a functional group (hydroxyl, hydroxymethyl, etc.) that can coordinate with the oxide. The technique disclosed herein is preferably implemented such that the adhesive composition is completely free of such chelating compounds or that the content of such chelating compounds is 1% by weight or less. According to this method, adhesive sheets with superior adhesive strength can be achieved.

[0115] (Adhesive composition)

[0116] The adhesive layer in the disclosed technology can be a layer formed from an adhesive composition comprising a base polymer and a tackifying resin. There are no particular limitations on the form of the adhesive composition disclosed herein; for example, it can be a solvent-based adhesive composition containing the composition described above in an organic solvent (adhesive component), an adhesive composition in which the adhesive is dispersed in an aqueous solvent (water-dispersible type, typically an aqueous emulsion type), a hot-melt adhesive composition, etc. From the viewpoint of the permeability and adhesion of the fiber sheet, in some embodiments, an adhesive layer formed from a solvent-based adhesive composition is preferred.

[0117] Solvent-based adhesive compositions are typically prepared as solutions containing the aforementioned components in an organic solvent. The organic solvent can be appropriately selected from known or conventional organic solvents. For example, any one or a mixture of two or more solvents selected from 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; haloalkanes such as 1,2-dichloroethane; ketones such as methyl ethyl ketone and acetylacetone; etc. There are no particular limitations; generally, it is appropriate to prepare the aforementioned solvent-based adhesive compositions with a solids content (NV) of 30% to 65% by weight (e.g., 40% to 55% by weight). When the NV is too low, manufacturing costs tend to increase; when the NV is too high, workability, such as coatability, may sometimes decrease.

[0118] As for methods of obtaining adhesive sheets from adhesive compositions, various known methods can be applied. For example, a method that forms an adhesive layer by directly applying (typically coating) the adhesive composition onto a fiber sheet and drying it (direct method) is preferred. Alternatively, a method that forms an adhesive layer on a surface with good peelability (e.g., the surface of a release liner) and drying it, and then transferring the adhesive layer onto the fiber sheet (transfer method) is also possible.

[0119] The adhesive composition can be coated using known or conventional coating machines such as gravure roller coaters, reverse roller coaters, roller lick coaters, dip roller coaters, doctor blade coaters, and spray coaters. From the viewpoint of promoting crosslinking reactions and improving manufacturing efficiency, drying the adhesive composition under heat is preferred. Typically, a drying temperature of about 40°C to about 150°C (typically about 40°C to about 120°C, for example about 50°C to about 120°C, and further about 70°C to about 100°C) is preferred. There is no particular limitation on the drying time, which can be set from about tens of seconds to about a few minutes (e.g., within about 5 minutes, preferably about 30 seconds to 2 minutes). Additional drying steps can then be added as needed. The adhesive layer is typically formed continuously, but depending on the purpose and application, it can also be formed into regular or irregular patterns such as dots or stripes.

[0120] In the adhesive sheet disclosed herein, there is no particular limitation on the thickness of the adhesive layer; a thickness greater than or equal to the thickness of the fiber sheet is appropriate, for example, it can be set to be greater than 50 μm. From the viewpoint of improving peel strength, the adhesive sheet disclosed herein is preferably implemented with an adhesive layer thickness greater than 65 μm (more preferably greater than 75 μm, for example, greater than 90 μm). In the adhesive sheet disclosed herein, since the adhesive layer is reinforced with a fiber sheet having an appropriate thickness and packing density, peel strength can be effectively improved by thickening the adhesive layer. In some embodiments, the thickness of the adhesive layer can be greater than 100 μm, greater than 120 μm, or greater than 140 μm. Furthermore, from the viewpoint of the productivity of the adhesive sheet and the cohesiveness of the adhesive layer, in some embodiments, the thickness of the adhesive layer can be, for example, less than 1000 μm, less than 500 μm, less than 250 μm, less than 190 μm, or less than 170 μm.

[0121] It should be noted that in the case of an adhesive sheet with adhesive layers on both sides of the fiber sheet, the thickness of the aforementioned adhesive layer refers to the thickness of the adhesive layer on each single side. The thickness of the adhesive layer (first adhesive layer) laminated on the first side of the fiber sheet and the thickness of the adhesive layer (second adhesive layer) laminated on the second side of the fiber sheet can be the same or different. Similarly, the composition of the first adhesive layer (e.g., the type and amount of tackifying resin, and, if a crosslinking agent is used, the type and amount of crosslinking agent) can be the same or different from the composition of the second adhesive layer.

[0122] <Adhesive Sheet>

[0123] The total thickness of the adhesive sheet disclosed herein is typically set to be greater than the thickness of the fiber sheet contained in the adhesive sheet and less than 2000 μm. In some embodiments, the total thickness of the adhesive sheet may be less than 1000 μm, less than 500 μm, less than 400 μm, or less than 350 μm. Furthermore, the total thickness of the adhesive sheet may be, for example, 60 μm or more; from the viewpoint of improving peel strength, it is preferably greater than 100 μm, more preferably greater than 150 μm, greater than 180 μm, greater than 200 μm, greater than 240 μm, or greater than 280 μm.

[0124] Furthermore, the total thickness of the adhesive sheet disclosed herein is typically 1.1 times or more the thickness of the fiber sheet contained in the adhesive sheet, for example, it can be 1.5 times or more. From the viewpoint of improving peel strength, it is advantageous for the total thickness of the adhesive sheet to be 3.0 times or more the thickness of the fiber sheet, preferably 4.0 times or more, more preferably 4.5 times or more (e.g., about 4.5 times to about 6.5 times). In some embodiments, the total thickness of the adhesive sheet can be 7.0 times or more, 10 times or more, 12 times or more (e.g., about 12 times to about 25 times), or 15 times or more the thickness of the fiber sheet. The total thickness of the adhesive sheet can, for example, be 50 times or less the thickness of the fiber sheet. In some embodiments, the total thickness of the adhesive sheet can be 30 times or less, 25 times or less, 20 times or less, 16 times or less, 11 times or less, or 8.0 times or less the thickness of the fiber sheet.

[0125] There are no particular limitations on the 180-degree peel strength of the adhesive sheet disclosed herein against stainless steel sheets. A peel strength of 20 N / 20 mm or more is suitable, preferably 30 N / 20 mm or more, more preferably 35 N / 20 mm or more, and even more preferably 40 N / 20 mm or more. The adhesive sheet disclosed herein may also preferably be implemented with a 180-degree peel strength of 44 N / 20 mm or more, 47 N / 20 mm or more, or 50 N / 20 mm or more. Furthermore, the aforementioned 180-degree peel strength is typically 100 N / 20 mm or less, preferably 80 N / 20 mm or less, can be 70 N / 20 mm or less, or can be 65 N / 20 mm or less.

[0126] Here, the 180° peel strength of the adhesive sheet can be understood as follows: It is pressed onto a stainless steel sheet (more specifically, SUS304BA sheet) as the substrate, placed at 23°C and 50%RH for 30 minutes, and then the 180° peel adhesion is measured according to JISZ 0237 at a peel angle of 180° and a tensile speed of 300 mm / min. During the measurement, it is preferable to reinforce the adhesive sheet by attaching a suitable backing material (e.g., a 25 μm thick PET film) to the back side of the adhesive sheet (the surface opposite to the side attached to the substrate). The 180° peel strength of the adhesive sheet is measured more specifically by the method described in the examples described later.

[0127] The adhesive sheet disclosed herein can be satisfactorily used, for example, for joining and fixing components contained in various products such as OA equipment, home appliances, and automobiles.

[0128] The following are among the matters disclosed in this specification.

[0129] (1) An adhesive sheet comprising a fiber sheet and an adhesive layer laminated on the fiber sheet, wherein, The aforementioned adhesive layer comprises a base polymer and a tackifying resin. The aforementioned base polymer is a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound. The above-mentioned tackifying resins include tackifying resins with a softening point of less than 120°C and tackifying resins with a softening point of more than 120°C. The thickness of the aforementioned fiber sheet is 15 μm or more and 50 μm or less, and the bulk density is 0.25 g / cm³. 3 Above and 0.50 g / cm 3 the following.

[0130] (2) The adhesive sheet as described in (1) above, wherein the bulk density of the fiber sheet is greater than 0.35 g / cm³. 3 And less than or equal to 0.50 g / cm 3 .

[0131] (3) The adhesive sheet as described in (2) above, wherein the basis weight of the fiber sheet is 15 g / m². 2 Above and 25g / m 2 the following.

[0132] (4) The adhesive sheet as described in (2) above, wherein the basis weight of the fiber sheet is less than 10 g / m³. 2 And the thickness is more than 15μm and less than 25μm.

[0133] (5) The adhesive sheet as described in any one of (1) to (4) above, wherein the thickness of the adhesive sheet is more than 4 times the thickness of the fiber sheet.

[0134] (6) The adhesive sheet as described in any one of (1) to (5) above, wherein the 180-degree peel strength of the adhesive sheet to the stainless steel plate is 40 N / 20 mm or more.

[0135] (7) The adhesive sheet as described in (6) above, wherein in the above 180-degree peel strength test, peeling is performed at the interface between the stainless steel plate and the adhesive sheet.

[0136] (8) The adhesive sheet as described in any one of (1) to (7) above, wherein the fibrous material constituting the fiber sheet is a natural fiber.

[0137] (9) The adhesive sheet as described in any one of (1) to (8) above, wherein the fiber sheet is a nonwoven fabric.

[0138] (10) The adhesive sheet as described in any one of (1) to (9) above, wherein the thickness of the adhesive layer is greater than 100 μm (e.g., greater than 120 μm).

[0139] (11) The adhesive sheet as described in any one of (1) to (10) above, wherein the total thickness of the adhesive sheet is greater than 150 μm.

[0140] (12) The adhesive sheet as described in any one of (1) to (11) above, wherein the adhesive sheet is configured as a double-sided adhesive sheet, the double-sided adhesive sheet comprising: the fiber sheet, the adhesive layer (first adhesive layer) laminated on one surface (first surface) of the fiber sheet, and the adhesive layer (second adhesive layer) laminated on the other surface (second surface) of the fiber sheet.

[0141] (13) A method for manufacturing an adhesive sheet, which is a method for manufacturing an adhesive sheet according to any one of (1) to (12) above, wherein the method for manufacturing an adhesive sheet comprises: Prepare the fiber sheets mentioned above; The adhesive layer is formed from an adhesive composition comprising the aforementioned base polymer and the aforementioned tackifying resin; and, The adhesive layer is laminated on the fiber sheet.

[0142] [Example]

[0143] The following describes some embodiments of the present invention, but it is not intended to limit the invention to the solutions shown in these embodiments. It should be noted that, unless otherwise specified, "parts" and "%" in the following description are based on weight. Furthermore, the characteristics described below were measured or evaluated in the manner described below.

[0144] <Preparation of Adhesive Compositions>

[0145] A 50% NV adhesive composition was prepared by mixing 100 parts of a styrene-isoprene block copolymer (manufactured by ZEON Corporation, Japan, product name "Quintac 3520", styrene content 15%, diblock ratio 78%) as the base polymer, 20 parts of an aromatic petroleum resin (manufactured by JX Nippon Oil & Energy Co., Ltd., product name "Nippon Oil Neopolymer 150", softening point 155℃, hydroxyl value less than 1mgKOH / g), 40 parts of terpene phenol resin, 30 parts of terpene resin, 0.75 parts of an isocyanate compound (manufactured by Tosoh Corporation, product name "Coronate L") based on solid content, 3 parts of an antioxidant, and toluene as a solvent.

[0146] Here, as a terpene phenolic resin, two products manufactured by Yasuhara Chemical Co., Ltd., under the trade name "YS Polystar S145" (softening point 145℃, hydroxyl value 100mgKOH / g) and "YS Polystar T145" (softening point 145℃, hydroxyl value 60mgKOH / g), are used in a 1:1 mass ratio, totaling 40 parts. As a terpene resin, "YS RESIN PX1150N" (softening point 115℃, hydroxyl value less than 1mgKOH / g) manufactured by Yasuhara Chemical Co., Ltd., is used. As an antioxidant, "IRGANOX CB612" (a blend of "IRGAFOS 168" and "IRGANOX 565" manufactured by BASF) is used in a 2:1 mass ratio.

[0147] <Making Adhesive Sheets>

[0148] (Example 1)

[0149] A sheet-like release liner was prepared by laminating a 25 μm thick polyethylene layer onto one side of a wood pulp paper and then subjecting it to a release treatment using a polysiloxane-based release agent. An adhesive layer with a thickness of 150 μm was formed on the release liner by applying the adhesive composition obtained above to the treated surface of the release liner and drying it. This adhesive layer was then bonded to the first side of a fiber sheet a having the thickness, bulk density, and basis weight shown in Table 1 to form a first adhesive layer. Similarly, an adhesive layer with a thickness of 150 μm was formed on the release liner and bonded to the second side of the fiber sheet a to form a second adhesive layer. In this manner, a laminate was obtained in which the first adhesive layer and the second adhesive layer are respectively laminated on the first and second sides of the fiber sheet, and the surface of each adhesive layer is protected by the release liner. Next, the laminate was subjected to a laminator at 100°C under a pressure of 0.3 MPa and a speed of 0.5 m / min, and then cured at 23°C for 1 hour to obtain the double-sided adhesive sheet involved in this example.

[0150] (Example 2~Example 7)

[0151] Except that fiber sheets b to g were used instead of fiber sheet a, the adhesive sheets involved in each example were produced in the same manner as those involved in Example 1.

[0152] It should be noted that fiber sheets a to f are: a: nonwoven fabric of 20% wood pulp and 80% hemp pulp; b: pulp-based nonwoven fabric; c: nonwoven fabric of 100% hemp pulp; d: pulp-based nonwoven fabric; e: nonwoven fabric of 100% hemp pulp; f: pulp-based nonwoven fabric. As fiber sheet g, commercially available photocopying paper is used.

[0153] <Determination of 180-degree peel strength>

[0154] The release liner covering one adhesive side of the double-sided adhesive sheet involved in each example was peeled off, and a 25 μm thick polyethylene terephthalate (PET) film was applied as a backing. The backed adhesive sheet was cut to dimensions of 20 mm wide and 100 mm long to prepare test pieces. At 23°C and 50% RH, the release liner covering the other adhesive side of the test piece was peeled off, and a 2 kg roller was used to press the test piece onto the surface of the substrate once. It was placed under the same conditions for 30 minutes, and then the 180° peel adhesion force (N / 20 mm) was measured using a tensile testing machine at a tensile speed of 300 mm / min according to JIS Z 0237. The measurement was performed three times (i.e., N=3), and their arithmetic mean was calculated. The results are shown in Table 1.

[0155]

[0156] As shown in Table 1, compared with the adhesive sheets of Examples 5-7, a thickness of 15 μm or more and 50 μm or less and a bulk density of 0.25 g / cm³ were used. 3 Above and 0.50 g / cm 3 The adhesive sheets of Examples 1-4 below show significantly high peel strength. Even better results were obtained in the adhesive sheets of Examples 1 and 4.

[0157] The specific examples of the present invention have been described in detail above, but these examples are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes solutions obtained by various modifications and alterations to the specific examples illustrated above.

[0158] Figure Labels

[0159] 1. Adhesive sheet

[0160] 11 First adhesive layer

[0161] 11A First Adhesive Surface

[0162] 12 Second adhesive layer

[0163] 12A Second Adhesive Surface

[0164] 15 Fiber Sheets

[0165] 21. Peeling the gasket

[0166] 21B Back

Claims

1. An adhesive sheet comprising a fiber sheet and an adhesive layer laminated on the fiber sheet, wherein, The adhesive layer comprises 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 includes tackifying resins with a softening point of less than 120°C and tackifying resins with a softening point of more than 120°C. The fiber sheet has a thickness of 15 μm or more and 20 μm or less, and its bulk density is greater than 0.35 g / cm³. 3 And less than or equal to 0.40 g / cm 3 Furthermore, the basis weight of the fiber sheet is greater than or equal to 4.5 g / m². 2 And less than 10g / m 2 ,or The fiber sheet has a thickness of 45 μm or more and 50 μm or less, and its bulk density is 0.45 g / cm³. 3 Above and 0.50 g / cm 3 The following, and the basis weight of the fiber sheet is 21 g / m². 2 Above and 25g / m 2 the following.

2. The adhesive sheet as claimed in claim 1, wherein, The thickness of the adhesive sheet is more than four times the thickness of the fiber sheet.

3. The adhesive sheet as described in claim 1, wherein, The adhesive sheet has a 180-degree peel strength of 40N / 20mm or higher against the stainless steel plate.

4. The adhesive sheet as claimed in claim 1, wherein, The fibrous material constituting the fiber sheet is a natural fiber.

5. The adhesive sheet as claimed in claim 1, wherein, The fiber sheet is a non-woven fabric.

6. The adhesive sheet as claimed in claim 1, wherein, The thickness of the adhesive layer is greater than 100 μm.

7. The adhesive sheet as claimed in claim 1, wherein, The total thickness of the adhesive sheet is greater than 150 μm.

8. The adhesive sheet as claimed in claim 1, wherein, The adhesive sheet is configured as a double-sided adhesive sheet, which includes: The fiber sheet; A first adhesive layer, wherein the first adhesive layer is the adhesive layer laminated on the first surface of the fiber sheet; and The second adhesive layer is the adhesive layer laminated on the second surface of the fiber sheet.

9. The adhesive sheet according to any one of claims 1 to 8, wherein, The total amount of the tackifying resin with a softening point of less than 120°C is 25 parts by weight or more relative to 100 parts by weight of the base polymer, and the total amount of the tackifying resin with a softening point of 120°C or more is 40 parts by weight or more relative to 100 parts by weight of the base polymer.

10. The adhesive sheet according to any one of claims 1 to 8, wherein, The total amount of the tackifying resin is less than 100 parts by weight relative to 100 parts by weight of the base polymer.

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