TWI833947B - Adhesive tape - Google Patents

Abstract

An object of the present invention is to provide an adhesive tape that has excellent flexibility and impact resistance, as well as excellent heat resistance. The adhesive tape of the present invention has adhesive layers on both sides of a foam base material. The foam base material contains a block copolymer having at least one hard block and one soft block. The soft block Composed of (meth)acrylic monomers.

Description

Adhesive tape

The present invention relates to an adhesive tape.

In portable electronic devices such as mobile phones and mobile information terminals (Personal Digital Assistants, PDAs), adhesive tapes are used for assembly (for example, Patent Documents 1 and 2). In addition, adhesive tapes are also used to fix vehicle-mounted electronic equipment parts such as vehicle-mounted panels to the vehicle body. Prior technical literature patent documents

Patent Document 1: Japanese Patent Application Publication No. 2009-242541 Patent Document 2: Japanese Patent Application Publication No. 2009-258274

[Problem to be solved by the invention]

Adhesive tapes used for fixing portable electronic equipment parts, vehicle-mounted electronic equipment parts, etc. are required to have high adhesion and impact resistance that will not peel off even if they are impacted. On the other hand, in recent years, portable electronic devices, vehicle-mounted electronic devices, etc. tend to have more complex shapes as they become more functional, so there is a tendency to attach adhesive tapes to places such as height differences, corners, and non-planar parts. Conditions of use. In this case, the adhesive tape is required to have excellent flexibility that can follow the shape of the adherend.

As an adhesive tape excellent in flexibility and impact resistance, an adhesive tape using a foam base material made of polyolefin resin foam is known. On the other hand, in recent years, with the increase in performance or integration, the temperature during operation of portable electronic equipment, vehicle-mounted electronic equipment, etc. has increased. When an adhesive tape using a foam base material made of polyolefin resin as mentioned above is used in such a machine that is exposed to high temperatures for a long time, there is a phenomenon that it is not heat-resistant and deforms and peels off.

An object of the present invention is to provide an adhesive tape that has excellent flexibility and impact resistance, as well as excellent heat resistance. [Technical means to solve the problem]

The present invention is an adhesive tape with adhesive layers on both sides of a foam base material. The foam base material contains a block copolymer with at least one hard block and one soft block. The above-mentioned The soft block is composed of (meth)acrylic monomers. Hereinafter, the present invention will be described in detail.

The adhesive tape of the present invention has adhesive layers on both sides of the foam base material. By using the above-mentioned foam base material, the adhesive tape of the present invention can exhibit excellent flexibility and impact resistance. The above-mentioned foam base material may have a continuous cell structure or an independent cell structure, and preferably has an independent cell structure. The above-mentioned foam base material may have a single-layer structure or a multi-layer structure. In addition, the same adhesive can be used on both sides of the adhesive layer, or different adhesives can be used.

The foam base material contains a block copolymer having at least one hard block and one soft block. The so-called hard block refers to a block that has high cohesion and functions like a pseudo-crosslinking point. The soft block refers to a soft block that exhibits rubber elasticity. Regarding block copolymers having hard blocks and soft blocks, the hard blocks and the soft blocks are difficult to be compatible with each other, and sometimes uneven formation occurs in which islands formed by agglomeration of the hard blocks are dispersed in a sea of soft blocks. phase separation structure. Furthermore, it is thought that by making the islands of the hard blocks serve as pseudo-crosslinking points, rubbery properties can be imparted to the copolymer, and high flexibility and impact resistance can be imparted to the obtained adhesive tape. Furthermore, it is considered that if the hard block has a crosslinkable functional group, further flexibility and impact resistance can be imparted to the obtained adhesive tape. The above-mentioned block copolymer can adopt a diblock structure in which hard block and soft block both exist on the main chain, and can also adopt a three-block structure in which hard block-soft block-hard block exists. However, as for further details, In terms of improving flexibility and impact resistance, it is preferable to have a triblock structure. In addition, the above-mentioned block copolymer may be a graft copolymer in which hard blocks and soft blocks exist respectively on the main chain and side chains. Examples of the graft copolymer include a styrene macromonomer-(meth)acrylic acid monomer copolymer.

If the above-mentioned hard block has a rigid structure, it is not particularly limited. It may be a single polymer of the above-mentioned monomer with a rigid structure, or it may be a copolymer composed of a plurality of monomers including the above-mentioned monomer with a rigid structure. things. Examples of the monomer having a rigid structure include vinyl aromatic compounds, compounds having a cyclic structure, compounds with shorter side chain substituents, and the like. Among these, in order to further improve impact resistance, it is more preferable that the hard block has a structure derived from a vinyl aromatic compound monomer. Examples of the vinyl aromatic compound monomer include styrene, α-methylstyrene, p-methylstyrene, chlorostyrene, and the like. Among them, styrene is preferred in terms of further improving impact resistance. In addition, in this specification, the structure derived from a vinyl aromatic compound monomer means a structure represented by the following general formulas (1) and (2).

In formulas (1) and (2), R ¹ represents a substituent. Examples of the substituent R ¹ include a phenyl group, a methylphenyl group, a chlorophenyl group, and the like.

When the block copolymer has the structure derived from the vinyl aromatic compound monomer, the content of the structure derived from the vinyl aromatic compound monomer in the block copolymer is preferably 1% by weight or more. 30 weight% or less. By setting the content of the structure derived from the vinyl aromatic compound monomer to the above range, flexibility and impact resistance can be further improved. A more preferred lower limit for the content of the structure derived from the vinyl aromatic compound monomer is 1.5% by weight, a further preferred lower limit is 2% by weight, a particularly preferred lower limit is 2.5% by weight, a more preferred upper limit is 24% by weight, and still more preferred The upper limit is 19% by weight, the upper limit of particularly good is 16% by weight, and the upper limit of excellent is 8% by weight.

The hard block preferably has a structure derived from a monomer having a crosslinkable functional group. If the hard block has a crosslinkable functional group, the rubbery properties of the block copolymer are improved by crosslinking, so the flexibility and impact resistance can be further improved. The above-mentioned cross-linkable functional groups may or may not be cross-linked. Even in the case of an uncross-linked structure, through the interaction between the functional groups, the cohesion within the block will be improved, and the softness and impact resistance will also be improved. Improvement, but preferably cross-linking. In addition, in this specification, the structure derived from the monomer which has a crosslinkable functional group means the structure represented by the following general formula (3), (4).

Here, R ² represents a substituent. The substituent R ² may contain an alkyl or ether group, carbonyl group, ester group, carbonate group, amide group, urethane group, etc. as its constituent elements, and may contain a carboxyl group, a hydroxyl group, an epoxy group, a double bond, a triple bond, or a carboxyl group. At least one functional group among bond, amine group, amide group, nitrile group, etc.

The above-mentioned monomers having crosslinkable functional groups are not particularly limited, and examples thereof include: carboxyl-containing monomers, hydroxyl-containing monomers, epoxy-containing monomers, double-bond-containing monomers, triple-bond-containing monomers, and amine-containing monomers. based monomers, amide-containing monomers, nitrile-containing monomers, etc. Among them, in terms of further improving flexibility and impact resistance, it is preferable to select from a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an epoxy group-containing monomer, a amide group-containing monomer, and a double bond-containing monomer. And at least one of the group consisting of three-bond monomers. Examples of the hydroxyl-containing monomer include 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and the like. Examples of the carboxyl group-containing monomer include (meth)acrylic acid and the like. Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate and the like. Examples of the amide group-containing monomer include (meth)acrylamide. Examples of the double bond-containing monomer include allyl (meth)acrylate, hexanediol di(meth)acrylate, and the like. Examples of the triple bond-containing monomer include propargyl (meth)acrylate. Among these, in terms of being able to impart more excellent flexibility and impact resistance to the adhesive tape, a carboxyl group-containing monomer is preferred, a (meth)acrylic monomer is more preferred, and acrylic acid is even more preferred. .

When the above-mentioned hard block is a copolymer of the above-mentioned monomer having a rigid structure and the above-mentioned monomer having a crosslinkable functional group, it is preferred that the above-mentioned hard block contains 0.1% by weight or more and 30% by weight or less of the above-mentioned monomer derived from The structure of a monomer with cross-linking functional groups. By setting the content of the structure derived from the monomer having a crosslinkable functional group in the hard block to the above range, flexibility and impact resistance can be further improved. A more preferable lower limit of the content of the structure derived from the monomer having a cross-linkable functional group is 0.5% by weight, a further preferable lower limit is 1 wt%, a more preferable upper limit is 25 wt%, and a further preferable upper limit is 20 wt%.

The soft block is composed of (meth)acrylic monomers. Since the soft block is composed of a (meth)acrylic monomer, it is possible to impart heat resistance to the obtained adhesive tape, thereby suppressing deformation or peeling of the adhesive tape even when exposed to high temperatures for a long period of time. The above-mentioned (meth)acrylic monomer may be a single monomer, or a plurality of monomers may be used. In addition, monomers other than (meth)acrylic monomers may be used within the scope that the effects of the present invention are not lost.

The (meth)acrylic monomer used as the raw material of the soft block is not particularly limited as long as it has flexibility showing rubber elasticity. Examples include: (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester Ester, propyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, (meth)acrylate base) isostearyl acrylate, etc. Among them, in terms of easily achieving a balance between heat resistance and flexibility, methyl acrylate, ethyl acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are preferred, and further preferred It is methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate.

As the (meth)acrylic monomer used as the raw material of the soft block, it is preferable to use a (meth)acrylic monomer having a side chain carbon number of 2 or less. If a (meth)acrylic monomer with a side chain carbon number of 2 or less is used, the cross-linking of the obtained polymer chains increases and the cohesive force increases, so that the heat resistance or impact resistance can be further improved. Examples of the (meth)acrylic monomer having a side chain carbon number of 2 or less include methyl (meth)acrylate and ethyl (meth)acrylate, with methyl acrylate and ethyl acrylate being particularly preferred.

The preferred lower limit of the content of the (meth)acrylic monomer with a side chain carbon number of 2 or less in the soft block is 5% by weight. By including this lower amount, the cohesion-improving effect described above can be easily expressed. A more preferable lower limit is 10 wt%, a further preferable lower limit is 20 wt%, an excellent lower limit is 25 wt%, and an even more preferable lower limit is 30 wt%. A preferable upper limit of the content of the (meth)acrylic monomer with a side chain carbon number of 2 or less in the soft block is 90% by weight. If the upper limit is exceeded, the cohesive force becomes too high and the flexibility becomes low, and the flexibility as an adhesive tape is lost. A more preferable upper limit is 85% by weight, a further preferable upper limit is 80% by weight, an excellent upper limit is 75% by weight, and a particularly preferable upper limit is 70% by weight.

It is preferable that the block copolymer contains 1% by weight or more and 40% by weight or less of the hard block. By setting the content of the hard block within the above range, a foam base material excellent in flexibility, impact resistance, and heat resistance can be formed. From the viewpoint of further improving softness, impact resistance and heat resistance, a more preferable lower limit of the content of the hard block is 2 wt%, a further preferable lower limit is 2.5 wt%, a particularly preferable lower limit is 3 wt%, and more A preferable upper limit is 35%, a further preferable upper limit is 30%, a further preferable upper limit is 26 wt%, a further preferable upper limit is 20 wt%, a particularly preferable upper limit is 17 wt%, and an excellent upper limit is 8 wt%.

Preferably, the weight average molecular weight of the above-mentioned block copolymer is 50,000 to 800,000. By setting the weight average molecular weight of the block copolymer within the above range, flexibility, impact resistance, and heat resistance can be further improved. A more preferable lower limit of the weight average molecular weight of the above-mentioned block copolymer is 75,000, and a more preferable upper limit is 600,000. In addition, the above-mentioned weight average molecular weight can be measured by, for example, the GPC method. "2690 Separations Module" manufactured by Water Co., Ltd. can be used as the measurement machine, "GPCKF-806L" manufactured by Showa Denko Co., Ltd. can be used as the column, and ethyl acetate can be used. As a solvent, the measurement was performed under the conditions of sample flow rate 1 mL/min and column temperature 40°C.

In order to obtain the above block copolymer, the raw material monomers of the hard block and the soft block are subjected to free radical reactions respectively in the presence of a polymerization initiator to obtain the hard block and the soft block, and then the two are reacted Reaction or copolymerization, or after obtaining the hard block by the above method, then adding the raw material monomers of the soft block for copolymerization. As a method for advancing the radical reaction, that is, a polymerization method, conventionally known methods can be used, and examples thereof include solution polymerization (boiling point polymerization or isothermal polymerization), emulsion polymerization, suspension polymerization, block polymerization, and the like.

The above-mentioned foam base material may contain additives such as antistatic agents, release agents, antioxidants, weathering agents, and crystal nucleating agents, or resin modifiers such as polyolefins, polyesters, polyamides, and elastomers.

The apparent density of the above-mentioned foam base material is preferably 0.3 g/cm ³ or more and 0.75 g/cm ³ or less. By setting the apparent density of the foam base material within the above range, it is possible to produce an adhesive tape having better flexibility and impact resistance while maintaining strength. From the viewpoint of further improving the strength, softness and impact resistance of the adhesive tape, a more preferable lower limit of the above-mentioned foam base material is 0.33 g/cm ³ , a more preferable upper limit is 0.73 g/cm ³ , and a further preferable lower limit is 0.35 g/cm ³ , and a more preferable upper limit is 0.71 g/cm ³ . Here, the apparent density refers to the density of the foam base material calculated from the weight of the adhesive tape when the density of the adhesive in the adhesive tape is considered to be 1.0 g/cm ³ . In addition, the above-mentioned apparent density can be measured using an electronic hydrometer (for example, "ED120T" manufactured by MIRAGE Co., Ltd.) in accordance with JIS K 6767.

The gel fraction of the above-mentioned foam base material is preferably 90% or less. By setting the gel fraction of the foam base material to the above range, the impact resistance of the obtained adhesive tape can be further improved. From the viewpoint of further improving the impact resistance of the adhesive tape, a more preferable upper limit of the gel fraction is 85%, and a more preferable upper limit is 80%. The lower limit of the above-mentioned gel fraction is not particularly limited, but for example, it is 10% or more, excellent is 20% or more, and particularly optimal is 35% or more. The gel fraction can be adjusted by crosslinking at least one of the hard block and the soft block. In addition, the above-mentioned gel fraction can be measured by the following method. Only 0.1 g of the foam base material was taken out from the obtained adhesive tape, immersed in 50 ml of ethyl acetate, and vibrated using a vibration machine at a temperature of 23°C and 120 rpm for 24 hours. After vibration, a metal mesh (mesh #200 mesh) is used to separate the ethyl acetate from the foam base material that has been swollen by absorbing the ethyl acetate. The separated foam base material was dried at 110° C. for 1 hour. The weight of the foam base material including the metal mesh after drying is measured, and the gel fraction of the foam base material is calculated using the following formula. Gel fraction (weight%) = 100×(W1-W2)/W0 (W0: Initial weight of the foam base material, W1: Weight of the foam base material including the metal mesh after drying, W2: Initial weight of the metal mesh)

The foam base material preferably has a cross-linked structure formed between the main chains of the resin constituting the foam base material by adding a cross-linking agent. By forming a cross-linked structure between the main chains of the resin constituting the foam base material, peeling stress applied intermittently can be dispersed, and the heat resistance and impact resistance of the adhesive tape can be further improved. The cross-linking agent is not particularly limited and can be appropriately selected according to the functional groups of the resin constituting the foam base material. Specific examples thereof include isocyanate cross-linking agents, aziridine cross-linking agents, epoxy cross-linking agents, metal chelate cross-linking agents, and the like. Among them, in terms of being able to cross-link "a resin having an alcoholic hydroxyl group or a carboxyl group that can further improve flexibility and impact resistance", an epoxy-based cross-linking agent or an isocyanate-based cross-linking agent is preferred. Furthermore, the isocyanate cross-linking agent cross-links the alcoholic hydroxyl group or carboxyl group in the resin constituting the foam base material and the isocyanate group of the cross-linking agent. Furthermore, the epoxy cross-linking agent cross-links the carboxyl group in the resin constituting the foam base material and the epoxy group of the cross-linking agent. The amount of the crosslinking agent added is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 7 parts by weight relative to 100 parts by weight of the resin that is the main component of the foam base material.

The average cell diameter of the cells in the foam base material is preferably 80 μm or less. By setting the average cell diameter of the foam base material within the above range, the balance between strength, flexibility, and impact resistance of the obtained adhesive tape can be further improved. The average cell diameter of the foam base material is more preferably 60 μm or less, further preferably 55 μm or less. The lower limit of the average cell diameter of the foam base material is not particularly limited, but from the viewpoint of ensuring flexibility, it is preferably 20 μm or more, and more preferably 30 μm or more. In addition, the above-mentioned average bubble diameter can be measured by the following method. First, the foam base material was cut into 50 mm squares, immersed in liquid nitrogen for 1 minute, and then cut with a razor blade on the surface perpendicular to the thickness direction of the foam base material. Then, use a digital microscope (for example, "VHX-900" manufactured by Keyence Corporation, etc.) to take an enlarged photo of the cut surface at a magnification of 200 times, and measure the longest air chamber of all the air cells within the thickness × 2 mm range. Chamber diameter (diameter of bubble). Repeat this operation 5 times, calculate the average value of all the obtained air chamber diameters, and thereby calculate the average bubble diameter.

The thickness of the above-mentioned foam base material is not particularly limited, but a preferred lower limit is 40 μm and a preferred upper limit is 2900 μm. By setting the thickness of the foam base material within the above range, the adhesive tape of the present invention can be suitably used for fixing portable electronic device parts, vehicle-mounted electronic device parts, and the like. From the viewpoint of being more suitable for fixing the above-mentioned parts and the like, the lower limit of the thickness of the foam base material is preferably 60 μm, the upper limit is more preferably 1900 μm, the lower limit is more preferably 80 μm, and the upper limit is more preferably 80 μm. The upper limit is 1400 μm, the lower limit of the best is 100 μm, and the upper limit of the best is 1000 μm.

The above-mentioned foam base material only needs to have a bubble structure, and the manufacturing method is not particularly limited. Examples of methods for producing the foam base material include a method of producing the foam base material by the action of a foaming gas, or a method of producing the foam base material by blending hollow spheres into a raw material matrix. Among them, the foam produced by the latter method is called composite foam (syntactic foam). In terms of superior impact resistance and heat resistance, it is preferable that the foam base material is a composite foam. By using the foam base material as a composite foam, it is possible to obtain an independent cell type foam with a uniform size distribution of the foamed cells. Therefore, the density of the entire foam base material becomes more constant and can be further improved. Impact resistance. In addition, compared with other foams, composite foam is less prone to irreversible collapse at high temperatures and high pressures, so it shows higher heat resistance. As composite foam materials, there are composite foam materials having a foam structure composed of hollow inorganic particles, and composite foam materials having a foam structure composed of hollow organic particles. From the perspective of softness, composite foam materials having a foam structure composed of hollow organic particles Composite foam materials with a foamed structure are preferred.

Examples of the hollow organic fine particles include Expancel DU Series (manufactured by Japan Fillite Co., Ltd.), ADVANCELL EM Series (manufactured by Sekisui Chemical Industry Co., Ltd.), and the like. Among them, Expancel461-20 (the average air chamber diameter after foaming under optimal conditions is 20 μm) and Expancel461- are preferred because it is easy to design the air chamber diameter after foaming in an area with higher effect 40 (the average air chamber diameter after foaming under the best conditions is 40 μm), Expancel043-80 (the average air chamber diameter after foaming under the best conditions is 80 μm), ADVANCELL EML101 (the average air chamber diameter after foaming under the best conditions The average air chamber diameter is 50 μm).

When the foam base material is composed of a foam other than the composite foam, the foaming agent is not particularly limited, and conventionally known foaming agents such as thermal decomposition foaming agents can be used.

The above-mentioned adhesive layer is not particularly limited, and examples include an acrylic adhesive layer, a rubber-based adhesive layer, a urethane adhesive layer, a polysiloxane-based adhesive layer, and the like. Among them, an acrylic adhesive layer containing an acrylic copolymer is preferred because it has excellent heat resistance and can be adhered to a variety of adherends.

From the viewpoint of good adhesion at low temperatures due to improved initial viscosity, the acrylic copolymer constituting the acrylic adhesive layer preferably contains butyl acrylate and/or 2-ethylhexyl acrylate. Obtained by copolymerization of monomer mixture. Among them, it is more preferable to obtain it by copolymerizing a monomer mixture containing butyl acrylate and 2-ethylhexyl acrylate. The preferred lower limit of the content of the above-mentioned butyl acrylate in the total monomer mixture is 40% by weight, and the preferred upper limit is 80% by weight. By setting the content of butyl acrylate within the above range, both high adhesive force and viscosity can be achieved. The preferred lower limit of the content of the above-mentioned 2-ethylhexyl acrylate in the total monomer mixture is 10% by weight, the preferred upper limit is 100% by weight, the preferred lower limit is 30% by weight, and the preferred upper limit is 80% by weight. %, a further preferable lower limit is 50 wt%, and a further preferable upper limit is 60 wt%. By setting the content of the 2-ethylhexyl acrylate within the above range, high adhesive force can be exerted.

The above-mentioned monomer mixture may also contain other copolymerizable polymerizable monomers other than butyl acrylate and 2-ethylhexyl acrylate if necessary. Examples of other copolymerizable polymerizable monomers include alkyl (meth)acrylate whose alkyl group has 1 to 3 carbon atoms, and alkyl (meth)acrylate whose alkyl group has 13 to 18 carbon atoms. esters, functional monomers, etc. Examples of the (meth)acrylic acid alkyl ester in which the alkyl group has 1 to 3 carbon atoms include: (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid n-propyl ester, Isopropyl (meth)acrylate, etc. Examples of the (meth)acrylic acid alkyl ester in which the alkyl group has 13 to 18 carbon atoms include tridecyl methacrylate, stearyl (meth)acrylate, and the like. Examples of the functional monomer include: (meth)hydroxyalkyl acrylate, glycerol dimethacrylate, glycidyl (meth)acrylate, and 2-methacryloyloxyethyl isocyanate. Ester, (meth)acrylic acid, itaconic acid, maleic anhydride, crotonic acid, maleic acid, fumaric acid, etc.

In order to copolymerize the above-mentioned monomer mixture to obtain the above-mentioned acrylic copolymer, it is only necessary to subject the above-mentioned monomer mixture to a free radical reaction in the presence of a polymerization initiator. As a method of radically reacting the monomer mixture, that is, a polymerization method, conventionally known methods can be used, and examples thereof include solution polymerization (boiling point polymerization or isothermal polymerization), emulsion polymerization, suspension polymerization, block polymerization, and the like.

The preferred lower limit of the weight average molecular weight (Mw) of the acrylic copolymer is 400,000, and the preferred upper limit is 1.5 million. By setting the weight average molecular weight of the acrylic copolymer to the above range, high adhesive force can be exerted. From the viewpoint of further improving the adhesive force, a more preferable lower limit of the weight average molecular weight is 500,000, and a more preferable upper limit is 1.4 million. In addition, the weight average molecular weight (Mw) refers to the weight average molecular weight converted to standard polystyrene obtained by GPC (Gel Permeation Chromatography).

A preferable upper limit of the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the acrylic copolymer is 10.0. If Mw/Mn is 10.0 or less, the ratio of low molecular components can be suppressed, and the phenomenon of softening of the adhesive layer at high temperatures, lowering of bulk strength, and subsequent lowering of strength can be suppressed. From the same point of view, a more preferable upper limit of Mw/Mn is 5.0, and a further preferable upper limit is 3.0.

The adhesive layer may contain an adhesive imparting resin. Examples of the above-mentioned tackifier-imparting resin include rosin ester resin, hydrogenated rosin resin, terpene resin, terpenol resin, lavenderine-indene resin, alicyclic saturated hydrocarbon resin, and C5 petroleum resin. , C9 series petroleum resin, C5-C9 copolymer series petroleum resin, etc. These adhesion-imparting resins may be used alone, or two or more types may be used in combination.

The content of the adhesion-imparting resin is not particularly limited, but a preferred lower limit is 10 parts by weight and a preferred upper limit is 60 parts by weight based on 100 parts by weight of the resin (for example, acrylic copolymer) that is the main component of the adhesive layer. If the content of the adhesive imparting resin is 10 parts by weight or more, the reduction in the adhesive force of the adhesive layer can be suppressed. If the content of the adhesive imparting resin is 60 parts by weight or less, the decrease in adhesive force or viscosity caused by hardening of the adhesive layer can be suppressed.

The adhesive layer preferably has a cross-linked structure formed between the main chains of the resin constituting the adhesive layer (for example, the acrylic copolymer, the adhesion-imparting resin, etc.) by adding a cross-linking agent. The cross-linking agent is not particularly limited, and examples thereof include isocyanate-based cross-linking agents, aziridine-based cross-linking agents, epoxy-based cross-linking agents, metal chelate-type cross-linking agents, and the like. Among them, an isocyanate cross-linking agent is preferred. By adding an isocyanate cross-linking agent to the above-mentioned adhesive layer, the isocyanate group of the isocyanate-based cross-linking agent and the alcohol in the resin constituting the above-mentioned adhesive layer (such as the above-mentioned acrylic copolymer, the above-mentioned tackifying resin, etc.) The hydroxyl groups react to cross-link the adhesive layer. If a cross-linked structure is formed between the main chains of the resin constituting the adhesive layer, the adhesive layer can disperse the peeling stress applied intermittently, and the adhesive force of the adhesive tape can be further improved. The amount of the crosslinking agent added is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 7 parts by weight relative to 100 parts by weight of the resin (for example, the acrylic copolymer) that is the main component of the adhesive layer.

In order to improve the adhesion, the above-mentioned adhesive layer may also contain a silane coupling agent. The silane coupling agent is not particularly limited, and examples thereof include epoxy silanes, acrylic silanes, methacrylic silanes, amino silanes, isocyanato silanes, and the like.

In order to impart light-shielding properties, the adhesive layer may contain a coloring material. The coloring material is not particularly limited, and examples thereof include carbon black, aniline black, titanium oxide, and the like. Among them, carbon black is preferred in terms of being relatively cheap and chemically stable. The above-mentioned adhesive layer may optionally contain conventionally known microparticles and additives such as inorganic microparticles, conductive microparticles, antioxidants, foaming agents, organic fillers, and inorganic fillers.

The thickness of the above-mentioned adhesive layer is not particularly limited, with a preferred lower limit being 0.01 mm and a preferred upper limit being 0.1 mm. By setting the thickness of the adhesive layer within the above range, the adhesive tape of the present invention can be suitably used for fixing portable electronic device parts, vehicle-mounted electronic device parts, and the like. From the viewpoint of being more suitable for fixing the above-mentioned parts, etc., a better lower limit of the thickness of the above-mentioned adhesive layer is 0.015 mm, and a better upper limit is 0.09 mm.

The adhesive tape of the present invention preferably has a resin layer on at least one side of the foam base material. By having the above-mentioned resin layer, the strength of the obtained adhesive tape is improved, and therefore the impact resistance can be further improved. In particular, the durability (tumble resistance) when impacts are repeatedly applied can be improved. The above-mentioned resin layer may be formed on one side of the above-mentioned foam base material, or may be formed on both sides of the above-mentioned foam base material. It is preferably formed on one side of the above-mentioned foam base material.

The resin constituting the above resin layer preferably has heat resistance. Examples of the heat-resistant resin constituting the resin layer include polyester resins such as polyethylene terephthalate, acrylic resins, polysilicone resins, phenol resins, polyimide, and polycarbonate. wait. Among them, in terms of obtaining an adhesive tape with excellent flexibility, acrylic resin and polyester resin are preferred, and polyethylene terephthalate is more preferred.

The above-mentioned resin layer may also be colored. By coloring the resin layer, light-shielding properties can be imparted to the adhesive tape. The method for coloring the resin layer is not particularly limited, and examples include kneading particles such as carbon black and titanium oxide or fine bubbles into the resin constituting the resin layer, and applying ink to the surface of the resin layer.

The above-mentioned resin layer may optionally contain conventionally known fine particles and additives such as inorganic fine particles, conductive fine particles, plasticizers, adhesion-imparting agents, ultraviolet absorbers, antioxidants, foaming agents, organic fillers, inorganic fillers, and the like.

The thickness of the above-mentioned resin layer is not particularly limited, but a preferred lower limit is 5 μm and a preferred upper limit is 100 μm. By setting the thickness of the resin layer within the above range, both the operability and impact resistance of the adhesive tape can be achieved. From the viewpoint of further balancing operability and impact resistance, a more preferable lower limit of the thickness of the resin layer is 10 μm, and a more preferable upper limit is 70 μm.

The adhesive tape of the present invention may also have other layers other than the above-mentioned foam base material, the above-mentioned adhesive layer and the above-mentioned resin layer if necessary.

The adhesive tape of the present invention preferably has a ratio of the thickness of the adhesive layer to the thickness of the foam base material (thickness of the adhesive layer/thickness of the foam base material) of 0.1 or more and 2 or less. By setting the ratio of the thickness of the adhesive layer to the foam base material within the above range, the strength of the entire adhesive tape obtained is increased, and therefore the impact resistance can be further improved. The ratio of the thickness of the adhesive layer to the thickness of the foam base material is more preferably 0.15 or more, and more preferably 1.2 or less. Furthermore, the thickness of the adhesive layer mentioned above refers to the total thickness of the adhesive layers on both sides.

The thickness of the adhesive tape of the present invention is not particularly limited. The preferred lower limit is 0.04 mm, the more preferred lower limit is 0.05 mm, the preferred upper limit is 2 mm, and the more preferred upper limit is 1.5 mm. By setting the thickness of the adhesive tape of the present invention within the above range, an adhesive tape having excellent workability can be produced.

The manufacturing method of the adhesive tape of the present invention is not particularly limited, and examples thereof include the following methods. First, apply an adhesive solution on the release film and let it dry to form an adhesive layer. Use the same method to form a second adhesive layer. Next, an unfoamed base material is produced by the above-mentioned method, and the above-mentioned resin layer is laminated on the above-mentioned unfoamed base material to form a laminated body. Thereafter, the obtained adhesive layer is bonded to both sides of the obtained laminate, and the unfoamed base material is foamed by heating to produce an adhesive tape.

The shape of the adhesive tape of the present invention is not particularly limited, and examples thereof include rectangular, frame-shaped, circular, oval, donut-shaped, and the like.

The adhesive tape of the present invention can exhibit excellent flexibility, impact resistance and heat resistance by using the above-mentioned block copolymer as a foam base material. On the other hand, the present inventors discovered after research that the above-mentioned foam base material contains the above-mentioned structure derived from the vinyl aromatic compound monomer, the above-mentioned structure derived from the monomer having a crosslinkable functional group, and the above-mentioned structure. In the case of a random copolymer derived from a (meth)acrylic monomer structure, it can also exhibit excellent flexibility, impact resistance and heat resistance. It is thought that the reason for this may be that the same interaction as the above-mentioned phase separation structure occurs at extremely small scales such as nanometer level or molecular level. In addition, in this specification, the structure derived from a (meth)acrylic acid-type monomer means the structure represented by the following general formula (5), (6).

Here, R ³ represents a side chain. Examples of side chain R ³ include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, dodecyl, and lauryl base, isostearyl base, etc.

Therefore, the present invention also provides an adhesive tape having adhesive layers on both sides of a foam base material, the foam base material containing a copolymer, and the copolymer having a structure derived from a vinyl aromatic compound monomer, derived from The structure of the monomer having a cross-linkable functional group and the structure derived from the (meth)acrylic monomer.

The copolymer is not particularly limited, and examples thereof include block copolymers and random copolymers. Among them, the soft block (including the block derived from the above-mentioned structure of the (meth)acrylic monomer) and the hard block (including the above-mentioned block derived from the structure of the vinyl aromatic compound monomer) adopt uneven phase separation. Since the hard blocks serve as pseudo-crosslinking points, the copolymer is given rubbery properties and can impart high flexibility and impact resistance to the obtained adhesive tape. Block copolymers are preferred. . Examples of block copolymers include diblock copolymers, triblock copolymers, and graft copolymers. From the viewpoint of formation of the above-mentioned layer separation, diblock copolymers and triblock copolymers are preferred, and more preferably Preferred are triblock copolymers.

When the copolymer is a block copolymer, the block copolymer preferably contains 1% by weight or more and 40% by weight or less of the hard block. By setting the content of the hard block within the above range, a foam base material excellent in flexibility, impact resistance, and heat resistance can be formed. From the viewpoint of further improving softness, impact resistance and heat resistance, a more preferable lower limit of the content of the hard block is 2 wt%, a further preferable lower limit is 2.5 wt%, a particularly preferable lower limit is 3 wt%, and more A preferable upper limit is 35%, a further preferable upper limit is 30%, a further preferable upper limit is 26 wt%, a further preferable upper limit is 20 wt%, a particularly preferable upper limit is 17 wt%, and an excellent upper limit is 8 wt%.

When the above-mentioned copolymer is a block copolymer, the weight average molecular weight of the block copolymer is preferably 50,000 to 800,000. By setting the weight average molecular weight of the block copolymer within the above range, flexibility, impact resistance, and heat resistance can be further improved. A more preferable lower limit of the weight average molecular weight of the above-mentioned block copolymer is 75,000, and a more preferable upper limit is 600,000.

In order to obtain the above block copolymer, the raw material monomers of the hard block and the soft block are subjected to free radical reactions respectively in the presence of a polymerization initiator to obtain the hard block and the soft block, and then the two are reacted Reaction or copolymerization, or after obtaining the hard block by the above method, then adding the raw material monomers of the soft block for copolymerization. As a method for advancing the radical reaction, that is, a polymerization method, conventionally known methods can be used, and examples thereof include solution polymerization (boiling point polymerization or isothermal polymerization), emulsion polymerization, suspension polymerization, block polymerization, and the like.

The vinyl aromatic compound monomer is not particularly limited, and examples thereof include styrene, α-methylstyrene, p-methylstyrene, chlorostyrene, and the like. Among them, styrene is preferred in terms of further improving impact resistance.

The content of the structure derived from the vinyl aromatic compound monomer in the copolymer is preferably 1% by weight or more and 30% by weight or less. A more preferable lower limit is 1.5 wt%, a further preferable lower limit is 2 wt%, a particularly preferable lower limit is 2.5 wt%, a better upper limit is 24 wt%, a further preferable upper limit is 19 wt%, and a particularly preferable upper limit is 16 wt%. The upper limit of excellence is 8% by weight.

The above-mentioned monomers having crosslinkable functional groups are not particularly limited, and examples thereof include: carboxyl-containing monomers, hydroxyl-containing monomers, epoxy-containing monomers, double-bond-containing monomers, triple-bond-containing monomers, and amine-containing monomers. based monomers, amide-containing monomers, nitrile-containing monomers, etc. Among them, in terms of further improving flexibility and impact resistance, it is preferable to be selected from the group consisting of hydroxyl group-containing monomers, carboxyl group-containing monomers, epoxy group-containing monomers, amide group-containing monomers, and double bond-containing monomers. At least one of the group consisting of monomers and monomers containing three bonds. Examples of the hydroxyl-containing monomer include 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and the like. Examples of the carboxyl group-containing monomer include (meth)acrylic acid and the like. Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate and the like. Examples of the amide group-containing monomer include (meth)acrylamide. Examples of the double bond-containing monomer include allyl (meth)acrylate, hexanediol di(meth)acrylate, and the like. Examples of the triple bond-containing monomer include propargyl (meth)acrylate and the like. Among these, carboxyl group-containing monomers are preferred in terms of being able to impart more excellent flexibility and impact resistance to the adhesive tape. The monomer is preferably a (meth)acrylic monomer, and further preferably acrylic acid.

The content of the structure derived from the monomer having a crosslinkable functional group in the copolymer is preferably 0.1% by weight or more and 30% by weight or less. A more preferred lower limit is 0.5% by weight, a further preferred lower limit is 1% by weight, a more preferred upper limit is 25% by weight, and a further preferred upper limit is 20% by weight.

The (meth)acrylic monomer is not particularly limited, and examples thereof include: (meth)acrylic acid methyl ester, (meth)ethyl acrylate, (meth)acrylic acid propyl ester, (meth)acrylic acid butyl ester, Pentyl (meth)acrylate, Hexyl (meth)acrylate, Heptyl (meth)acrylate, Octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylic acid Nonyl ester, decyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, isostearyl (meth)acrylate, etc. Among them, in terms of easily achieving a balance between heat resistance and flexibility, methyl acrylate, ethyl acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are preferred, and further preferred It is methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. The (meth)acrylic monomer may be a single monomer, or a plurality of monomers may be used. In addition, monomers other than (meth)acrylic monomers may be used within the scope that does not impair the effects of the present invention.

The content of the structure derived from the (meth)acrylic monomer in the copolymer is not particularly limited as long as the effect of the present invention is exerted, but is preferably 30% by weight or more and 99% by weight or less, and more preferably 40% by weight. More than 98% by weight and less, and more preferably 50% by weight and less than 97% by weight.

The above-mentioned foam base material is preferably a composite foam material having a foam structure composed of hollow organic fine particles. Examples of the hollow organic fine particles constituting the composite foam include ExpancelDU Series (manufactured by Japan Fillite Co., Ltd.) and ADVANCELLEM Series (manufactured by Sekisui Chemical Industry Co., Ltd.). Among them, Expancel461-20 (the average air chamber diameter after foaming under optimal conditions is 20 μm) and Expancel461- are preferred because it is easy to design the air chamber diameter after foaming in an area with higher effect 40 (the average air chamber diameter after foaming under the best conditions is 40 μm), Expancel043-80 (the average air chamber diameter after foaming under the best conditions is 80 μm), ADVANCELL EML101 (the average air chamber diameter after foaming under the best conditions The average air chamber diameter is 50 μm).

The above-mentioned foam base material may use the same additives as the foam layer of the adhesive tape using the above-mentioned block copolymer.

The apparent density of the above-mentioned foam base material is preferably 0.3 g/cm ³ or more and 0.75 g/cm ³ or less, more preferably 0.33 g/cm ³ or more and 0.73 g/cm ³ or less, still more preferably 0.35 g/cm ³ Above 0.71 g/ ^cm3 and below.

The gel fraction of the foam base material is preferably 90% or less, more preferably 85% or less, and still more preferably 80% or less. The lower limit of the above-mentioned gel fraction is not particularly limited, but for example, it is 10% or more, excellent is 20% or more, and particularly optimal is 35% or more.

The average cell diameter of the cells in the foam base material is preferably 80 μm or less, more preferably 60 μm or less, and still more preferably 55 μm or less. The average bubble diameter of the above-mentioned bubbles is preferably 20 μm or more.

The thickness of the above-mentioned foam base material is not particularly limited. The preferred lower limit is 40 μm, the more preferred lower limit is 60 μm, the preferred lower limit is 80 μm, the particularly preferred lower limit is 100 μm, the preferred upper limit is 2900 μm, and more A preferred upper limit is 1900 μm, a further preferred upper limit is 1400 μm, and a particularly preferred upper limit is 1000 μm.

As a method of producing the above-mentioned copolymer, for example, a solution in which a vinyl aromatic compound monomer, a monomer having a crosslinkable functional group, a (meth)acrylic monomer, and other monomers if necessary are mixed is present. The free radical reaction can be carried out under the conditions of polymerization initiator. As a method for advancing the radical reaction, conventionally known methods can be used, and examples thereof include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, block polymerization, and the like.

The manufacturing method of the above-mentioned foam base material is not particularly limited. For example, the following method can be cited: first, add a foaming agent to the solution of the above-mentioned copolymer, mix it, apply it into a desired shape, and dry it to form an unfoamed product. The base material is then heated to cause the foaming agent to foam. When the foam base material is a composite foam, the hollow organic fine particles are added to a solution of the copolymer, mixed, coated into a desired shape, and dried.

The adhesive tape preferably has a resin layer on at least one side of the foam base material. The resin constituting the above-mentioned resin layer is preferably heat-resistant, and examples thereof include polyester resins such as polyethylene terephthalate, acrylic resins, polysilicone resins, phenol resins, polyimide, and polycarbonate. Ester etc. Among them, in terms of obtaining an adhesive tape with excellent flexibility, acrylic resin and polyester resin are preferred, and polyethylene terephthalate is more preferred.

The thickness of the above-mentioned resin layer is not particularly limited. A preferred lower limit is 5 μm, a more preferred lower limit is 10 μm, a preferred upper limit is 100 μm, and a more preferred upper limit is 70 μm.

The above-mentioned adhesive layer may be of the same type as the adhesive layer of the adhesive tape using the above-mentioned block copolymer.

The use of the adhesive tape of the present invention is not particularly limited. Since it has excellent flexibility, impact resistance and heat resistance, it is suitable for use as an impact-resistant adhesive for fixing electronic parts such as portable electronic equipment parts and vehicle-mounted electronic equipment parts. belt. The adhesive tape of the present invention used for fixing electronic components is also one of the present invention. [Effects of the invention]

According to the present invention, it is possible to provide an adhesive tape that has excellent flexibility and impact resistance as well as excellent heat resistance.

The aspects of the present invention will be further described in detail below with reference to Examples, but the present invention is not limited to these Examples.

(Example 1) (1) Manufacturing of unfoamed base materials Add 0.902 g of 1,6-hexanedithiol, 1.83 g of carbon disulfide, and 11 mL of dimethylformamide into a two-necked flask, and stir at 25°C. 2.49 g of triethylamine was added dropwise over 15 minutes, and the mixture was stirred at 25°C for 3 hours. Then, 2.75 g of α-bromophenylacetic acid methyl ester was added dropwise over 15 minutes, and the mixture was stirred at 25° C. for 4 hours. Thereafter, 100 mL of extraction solvent (n-hexane: ethyl acetate = 50:50) and 50 mL of water were added to the reaction solution to perform liquid separation extraction. The organic layers obtained in the first and second separation extractions were mixed, and washed sequentially with 50 mL of 1 M hydrochloric acid, 50 mL of water, and 50 mL of saturated brine. After adding sodium sulfate to the washed organic layer and drying it, the sodium sulfate was filtered, and the filtrate was concentrated with an evaporator to remove the organic solvent. The RAFT agent is obtained by purifying the obtained concentrate using silica gel column chromatography.

Put 91.3 g of styrene (St), 8.7 g of acrylic acid (AA), 1.9 g of RAFT agent, and 0.2 g of 2,2'-azobis(2-methylbutyronitrile) (ABN-E) into a two-necked flask. , and the temperature was raised to 85°C while replacing the inside of the flask with nitrogen. Thereafter, the mixture was stirred at 85° C. for 6 hours to perform a polymerization reaction (first-stage reaction). After the reaction is completed, add 4000 g of n-hexane into the flask, stir to precipitate the reactant, filter the unreacted monomers (St, AA), and RAFT agent, and dry the reactant under reduced pressure at 70°C to obtain a copolymer. (hard block).

Put a mixture containing 100 g of butyl acrylate (BA), 0.058 g of ABN-E, and 50 g of ethyl acetate, and the copolymer (hard block) obtained above into a two-necked flask, with one side facing the inside of the flask. While replacing with nitrogen gas, the temperature was raised to 85°C. Thereafter, the polymerization reaction (second-stage reaction) was performed by stirring at 85°C for 6 hours, and a reaction liquid containing a block copolymer composed of a hard block and a soft block was obtained. Furthermore, the blending amount of the mixture (soft block) and the hard block is such that the content of the hard block in the obtained block copolymer reaches 17% by weight. Take a portion of the reaction solution, add 4000 g of n-hexane into it, stir to precipitate the reactant, filter the unreacted monomer (BA) and solvent, dry the reactant under reduced pressure at 70°C, and take out the embedded solution from the reaction solution. segment copolymer. The weight average molecular weight of the obtained block copolymer was measured by the GPC method, and the result was 250,000. Use "2690 Separations Module" manufactured by Water Corporation as the measurement device, use "GPC KF-806L" manufactured by Showa Denko Corporation as the column, use ethyl acetate as the solvent, and set the sample flow rate to 1 mL/min and the column temperature to 40°C. measured under the conditions.

The obtained block copolymer was dissolved in ethyl acetate so that the solid content ratio became 35%, and Expancel 461-40 (manufactured by Japan Fillite Co., Ltd.) was added as a foaming agent to 100 parts by weight of the block copolymer A. , marked as DU40 in the table) 0.5 parts by weight, and 0.2 parts by weight of Tetrad C (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a cross-linking agent, and then stir thoroughly to obtain a base material solution. Coat the obtained base material solution on the release-treated surface of a 50 μm polyethylene terephthalate (PET) film with release treatment on one side, and dry it at 90°C for 7 minutes. This resulted in an unfoamed base material. The thickness of the unfoamed base material was adjusted to reach 100 μm when the unfoamed base material was heated at 130° C. for 1 minute.

(2) Preparation of adhesive solution 52 parts by weight of ethyl acetate was added to a reactor equipped with a thermometer, a stirrer, and a cooling tube, and after nitrogen replacement, the reactor was heated to start reflux. After the ethyl acetate boiled, 0.08 parts by weight of azobisisobutyronitrile as a polymerization initiator was added 30 minutes later. A mixture of 70 parts by weight of butyl acrylate, 27 parts by weight of 2-ethylhexyl acrylate, 3 parts by weight of acrylic acid, and 0.2 parts by weight of 2-hydroxyethyl acrylate was added dropwise evenly and slowly over a period of 1 hour and 30 minutes. The monomer mixture is allowed to react. 30 minutes after the completion of the dropwise addition, 0.1 part by weight of azobisisobutyronitrile was added, and the polymerization reaction was continued for 5 hours. Ethyl acetate was added to the reactor to dilute it while cooling, thereby obtaining a solid content of 40% by weight. A solution of acrylic random copolymer. The weight average molecular weight of the obtained acrylic random copolymer was measured by the GPC method using "2690 Separations Module" manufactured by Water Corporation as a column. The result was 710,000. The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) was 5.5. To 100 parts by weight of the solid content of the obtained acrylic random copolymer, 15 parts by weight of polymerized rosin ester with a softening point of 150°C, 10 parts by weight of terpene phenol with a softening point of 145°C, and 10 parts by weight of rosin ester with a softening point of 70°C were added. share. Furthermore, 30 parts by weight of ethyl acetate (manufactured by Fuji Chemical Co., Ltd.) and 3.0 parts by weight of an isocyanate cross-linking agent (Coronate L45 produced by Tosoh Corporation) were added and stirred to obtain an adhesive solution.

(3) Manufacturing of adhesive tape Use a scraper to apply the obtained adhesive solution to a 50 μm polyethylene terephthalate (PET) film that has been released on one side so that the thickness of the dry film becomes 50 μm. Release treatment On the surface, heat at 110°C for 5 minutes to dry the coating solution to obtain an adhesive layer. Then, use the same operation to create another adhesive layer to obtain two adhesive layers. Thereafter, peel off the release film from the unfoamed base material obtained above, laminate the two adhesive layers obtained on both sides of the unfoamed base material, and let it stand for 48 hours in an environment of 40°C. hours. After 48 hours, take it out from the 40°C environment and heat it at 130°C for 1 minute to foam the base material to obtain an adhesive tape.

(4) Determination of belt density The density of the obtained adhesive tape was measured using an electronic hydrometer (ED120T manufactured by Mirage Corporation).

(5) Measurement of Apparent Density of Foam Base Material The density of the obtained foam base material was measured using an electronic hydrometer (ED120T manufactured by Mirage Corporation) in accordance with JISK-6767. From this result, the density of the adhesive was regarded as 1.0 g/cm ³ and the apparent density of the foam base material was calculated.

(6) Determination of gel fraction of foam base material Only 0.1 g of the foam base material was taken out from the obtained adhesive tape, immersed in 50 ml of ethyl acetate, and vibrated with a vibrator at a temperature of 23°C and 120 rpm for 24 hours. After vibration, a metal mesh (mesh #200 mesh) is used to separate the ethyl acetate from the foam base material that has been swollen by absorbing the ethyl acetate. The separated foam base material was dried at 110° C. for 1 hour. The weight of the foam base material including the metal mesh after drying is measured, and the gel fraction of the foam base material is calculated using the following formula. Gel fraction (weight%) = 100×(W1-W2)/W0 (W0: Initial weight of the foam base material, W1: Weight of the foam base material including the metal mesh after drying, W2: Initial weight of the metal mesh)

(Examples 2 to 24, 27 to 29) An adhesive tape was obtained in the same manner as in Example 1, except that the composition and thickness of the foam base material and the thickness of the adhesive layer were set as shown in Tables 1 and 2. Furthermore, in Example 20, the base material was foamed by heating at 150° C. for 1 minute. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1. The raw materials in the table are as follows. MA: Methyl acrylate AA: acrylic HEA: 2-hydroxyethyl acrylate EML101: ADVANCELL EML101 (manufactured by Sekisui Chemical Industry Co., Ltd.)

(Example 25) The composition and thickness of the foam base material and the thickness of the adhesive layer are as shown in Table 2. The base material solution is applied to the resin layer, which is a polyethylene terephthalate (PET) sheet with a thickness of 25 μm. (E5007 manufactured by Toyobo Co., Ltd.), except that the adhesive tape was obtained in the same manner as in Example 1. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Examples 26, 30 to 34) An adhesive tape was obtained in the same manner as in Example 25, except that the composition and thickness of the foam base material and the thickness of the adhesive layer were as shown in Table 2. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Example 35) (1) Manufacturing of unfoamed substrates 52 parts by weight of ethyl acetate was added to a reactor equipped with a thermometer, a stirrer, and a cooling tube, and after nitrogen replacement, the reactor was heated to start reflux. After the ethyl acetate boiled, 0.08 parts by weight of azobisisobutyronitrile as a polymerization initiator was added 30 minutes later. 93.888 parts by weight of butyl acrylate, 4 parts by weight of styrene macromonomer (recorded as AS-6S in the table, manufactured by Toagosei Co., Ltd.), and 1.92 parts by weight of acrylic acid were added dropwise evenly and slowly over a period of 1 hour and 30 minutes. , a monomer mixture composed of 0.192 parts by weight of 2-hydroxyethyl acrylate, and allowed to react. 30 minutes after the completion of the dropwise addition, 0.1 part by weight of azobisisobutyronitrile was added, and the polymerization reaction was carried out for 5 hours. While adding ethyl acetate to the reactor for dilution, the solid content 40 was obtained by cooling. % by weight solution of acrylic graft copolymer. The weight average molecular weight of the obtained acrylic graft copolymer was measured by the GPC method, and the result was 600,000. Use "2690 Separations Module" manufactured by Water Corporation as the measurement device, use "GPC KF-806L" manufactured by Showa Denko Corporation as the column, use ethyl acetate as the solvent, and set the sample flow rate to 1 mL/min and the column temperature to 40°C. measured under the conditions.

The obtained graft copolymer was dissolved in ethyl acetate so that the solid content ratio became 35%. To 100 parts by weight of the graft copolymer, 2.12 parts by weight of Expancel 461-40 as a foaming agent and 0.3 parts by weight were added. Use Tetrad C as a cross-linking agent and stir thoroughly to obtain a substrate solution. The obtained substrate solution was applied to the release-treated surface of a 50 μm polyethylene terephthalate (PET) film that had been released on one side and dried at 90°C for 7 minutes. An unfoamed base material composed of a graft copolymer was obtained. The thickness of the unfoamed base material was adjusted to reach 100 μm when the unfoamed base material was heated at 130° C. for 1 minute.

(2) Manufacturing of adhesive tape An adhesive tape was obtained in the same manner as in Example 1, except that the obtained unfoamed base material composed of the graft copolymer was used. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Example 36) An adhesive tape was obtained in the same manner as in Example 35, except that the contents of the hard block component and the soft block component were set as shown in Table 2. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Example 37) An unfoamed base material composed of a graft copolymer was obtained in the same manner as in Example 35, except that the composition and thickness of the foam base material were as shown in Table 2. Then, except that the thickness of the adhesive layer was as shown in Table 2, an adhesive tape was obtained in the same manner as in Example 25. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Example 38) (1) Manufacturing of unfoamed substrates 52 parts by weight of ethyl acetate was added to a reactor equipped with a thermometer, a stirrer, and a cooling tube, and after nitrogen replacement, the reactor was heated to start reflux. After the ethyl acetate boiled, 0.08 parts by weight of azobisisobutyronitrile as a polymerization initiator was added 30 minutes later. A monomer mixture consisting of 94.8 parts by weight of butyl acrylate, 3 parts by weight of styrene, 2 parts by weight of acrylic acid, and 0.2 parts by weight of 2-hydroxyethyl acrylate was added dropwise evenly and slowly over a period of 1 hour and 30 minutes. react. 30 minutes after the completion of the dropwise addition, 0.1 part by weight of azobisisobutyronitrile was added, and the polymerization reaction was carried out for 5 hours. While adding ethyl acetate to the reactor for dilution, it was cooled to obtain a solid content of 40% by weight. Solution of random copolymer. The weight average molecular weight of the obtained random copolymer was measured by the GPC method, and the result was 370,000. Use "2690 Separations Module" manufactured by Water Corporation as the measurement device, use "GPC KF-806L" manufactured by Showa Denko Corporation as the column, use ethyl acetate as the solvent, and set the sample flow rate to 1 mL/min and the column temperature to 40°C. measured under the conditions.

The obtained random copolymer was dissolved in ethyl acetate so that the solid content ratio became 35%. To 100 parts by weight of the random copolymer, 2.12 parts by weight of Expancel 461-40 as a foaming agent and 0.25 parts by weight were added. Use Tetrad C as a cross-linking agent and stir thoroughly to obtain a substrate solution. The obtained substrate solution was applied to the release-treated surface of a 50 μm polyethylene terephthalate (PET) film that had been released on one side and dried at 90°C for 7 minutes. An unfoamed base material composed of a random copolymer was obtained. The thickness of the unfoamed base material was adjusted to reach 100 μm when the unfoamed base material was heated at 130° C. for 1 minute.

(2) Manufacturing of adhesive tape An adhesive tape was obtained in the same manner as in Example 1, except that the obtained unfoamed base material composed of a random copolymer was used. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Example 39) An adhesive tape was obtained in the same manner as in Example 38, except that the composition of the foam base material was as shown in Table 2. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Example 40) An unfoamed base material composed of a random copolymer was obtained in the same manner as in Example 38, except that the composition and thickness of the foam base material were as shown in Table 2. Then, except that the thickness of the adhesive layer was as shown in Table 2, an adhesive tape was obtained in the same manner as in Example 25. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Comparative example 1) In the production of the adhesive tape, the adhesive tape was obtained in the same manner as in Example 1, except that no foaming agent was added, heating at 130° C. for 1 minute was not performed, and a foam base material was not formed. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Comparative example 2) (1) Preparation of foam base material Volara H03001 (polyethylene resin, manufactured by Sekisui Chemical Industry Co., Ltd., thickness 100 μm) was used as the foam base material. (2) Manufacturing of adhesive tape An adhesive tape was obtained in the same manner as in Example 1, except that the obtained base material was used. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Comparative example 3) (1) Preparation of foam base material Volara H0250012 (polyethylene resin, manufactured by Sekisui Chemical Industry Co., Ltd., thickness 120 μm) was used as the foam base material.

(2) Manufacturing of adhesive tape An adhesive tape was obtained in the same manner as in Example 1 except that the obtained base material was used. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Comparative example 4) (1) Manufacturing of base materials A 30% toluene solution of Septon 2063 (hydrocarbon resin, manufactured by Kuraray Co., Ltd.) was prepared, using 0.5 part by weight of Expancel 461-40 (manufactured by Japan Fillite Co., Ltd.) as a foaming agent based on 100 parts by weight of the solid content, and no cross-linking agent was used. , Except for this, an unfoamed base material was obtained in the same manner as in Example 1.

(2) Manufacturing of adhesive tape An adhesive tape was obtained in the same manner as in Example 1, except that the obtained unfoamed base material was used. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

(Comparative example 5) (1) Manufacturing of unfoamed substrates The acrylic random copolymer solution obtained in the preparation of the adhesive solution in Example 1 was used instead of the acrylic copolymer A, and 1 part by weight of the cross-linking agent was used relative to 100 parts by weight of the solid content of the acrylic random copolymer solution. , 0.5 parts by weight of foaming agent, except that the unfoamed base material was obtained in the same manner as in Example 1. In addition, the cross-linking agent and the foaming agent used are the following. Cross-linking agent: L-45E, manufactured by Tosoh Corporation Foaming agent: Expancel461-40, manufactured by Japan Fillite Company

(2) Manufacturing of adhesive tape An adhesive tape was obtained in the same manner as in Example 1, except that the obtained unfoamed base material was used. Each measurement was performed on the obtained adhesive tape in the same manner as in Example 1.

＜Evaluation＞ The adhesive tapes obtained in Examples and Comparative Examples were evaluated as follows. The results are shown in Tables 1 to 3.

(Evaluation of impact resistance) The obtained adhesive tape was punched into a square shape with an outer shape of 45 mm × 60 mm and a thickness of 1 mm. Attach one side of the punched adhesive tape to the center of an 80 mm × 115 mm, 2 mm thick zigzag stainless steel plate with a 40 mm × 40 mm hole in the center. Then, a 50 mm × 70 mm, 4 mm thick tempered glass plate was attached to the other side of the adhesive tape, pressed with a 5 kg weight for 10 seconds, and left to stand at 23°C for 24 hours to obtain a test laminate. body. The obtained laminated body was fixed to a stainless steel frame (inner diameter 60 mm × 90 mm) so that the tempered glass plate became the lower surface. Thereafter, a 150 g iron ball was dropped toward the center of the tempered glass plate. The falling height of the iron ball is increased, and the height of the iron ball when the tempered glass plate is peeled off the stainless steel plate is measured. When the tempered glass plate is peeled off from the stainless steel plate, the height of the iron ball is 60 cm or more. Mark it as "◎". When the tempered glass plate is peeled off from the stainless steel plate, the height of the iron ball is 40 cm or more but less than 60 cm. Mark it as "◎". "〇", mark "△" when the height of the iron ball when the tempered glass plate is peeled off the stainless steel plate is more than 20 cm and less than 40 cm, and the height of the iron ball when the tempered glass plate is peeled off the stainless steel plate is less than 20 cm. The situation is marked as "×" to evaluate the impact resistance.

(evaluation of retention power) A schematic diagram illustrating the retention test of the adhesive tape is shown in Figure 1 . First, attach one side (surface) of the test piece 1 with a size of 25 mm × 25 mm with the adhesive tape to the SUS plate 2, and move a 2 kg rubber roller from the other side (back) of the test piece 1 at 300 mm/min. The speed is one round trip. Then, the aluminum plate 3 was attached to the back of the test piece 1, and a 0.5 kg weight was applied from the side of the aluminum plate 3 for 10 seconds to press it together. Then, it was placed in an environment of 23°C and a relative humidity of 50% for 24 hours to produce a holding test. Samples for force testing. Place the holding force test sample at 100°C, install a 0.5kg or 1.0kg weight 4 on one end of the aluminum plate 3 in a manner that applies a load in the horizontal direction to the test piece 1 and the aluminum plate 3, and measure the weight after 1 hour. The offset length of the code. Also, install weight 4 of 1.0 kg and measure the deflection length after 2 hours. For the measurement results obtained, the case where the offset length is 0 (no offset) is marked as "◎", the case where the offset length is greater than 0 and less than 1 mm is marked as "△", and the case where the offset length is 1 mm or more or the adhesive tape peels off is marked as "×" to evaluate the holding power.

(evaluation of tumbling properties) Prepare 2 adhesive tapes cut out to 1 mm x 70 mm. Then, adhesive tapes were attached to each short side of a polycarbonate plate with a length of 72 mm, a width of 135 mm, and a thickness of 1 mm. Moreover, the surface of the polycarbonate plate with the adhesive tape attached and the polycarbonate plate with a length of 77 mm, a width of 150 mm, and a thickness of 4 mm were placed in such a way that the short sides of the two polycarbonate plates faced each other and the long sides faced each other. The two polycarbonate plates were joined together by overlapping them and applying pressure at 0.7 MPa for 15 seconds. Thereafter, the test sample was obtained by leaving it still at 23° C. for 24 hours. The obtained test sample was placed in a TD-1000A drum-type rotational drop tester (manufactured by Xinrong Electronic Measurement Co., Ltd.) and allowed to rotate at a speed of 12 rpm while maintaining a room temperature of 23°C. This causes the measurement sample to repeatedly drop from a height of 1 m. The polycarbonate sheet dropped more than 1,500 times when peeled off was marked as "◎", and the polycarbonate sheet dropped more than 1,000 times but less than 1,500 times was marked as "〇". , mark "×" when the number of drops when the polycarbonate sheet is peeled off is 1,000 times or less to evaluate the tumbling properties.

[Table 1] Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 twenty one Foam base material copolymer hard block content weight% 17 17 17 17 17 17 17 17 17 17 17 17 17 20 26 2 3 8 17 17 17 Composition (weight ratio) St - 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 75.0 91.3 91.3 91.3 91.3 91.3 AS-6S - - - - - - - - - - - - - - - - - - - - - - AA - 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 25.0 8.7 8.7 8.7 8.7 8.7 soft block content weight% 83 83 83 83 83 83 83 83 83 83 83 83 83 80 74 98 97 92 83 83 83 Composition (weight ratio) MA - - - - - - - - - - - - - - - - - - - - - - BA - 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 2EHA - - - - - - - - - - - - - - - - - - - - - - St - - - - - - - - - - - - - - - - - - - - - - AA - - - - - - - - - - - - - - - - - - - - - - HEA - - - - - - - - - - - - - - - - - - - - - - Content of structures derived from vinyl aromatic compound monomers weight% 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 18.3 23.7 1.5 2.7 7.3 15.5 15.5 15.5 weight average molecular weight ten thousand 25 25 25 25 25 25 25 25 25 25 25 25 25 27 twenty four 31 48 47 25 25 25 Foaming agent Kind - DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU20 EML101 DU80 number of copies parts by weight 0.5 0.89 1.23 3.23 6.19 6.53 2.13 2.13 2.13 2.13 2.13 2.13 2.13 2.13 2.55 2.13 2.13 2.13 2.13 2.13 2.13 Cross-linking agent number of copies parts by weight 0.2 0.2 0.2 0.2 0.2 0.2 0 0.05 0.2 0.4 0.45 0.5 0.55 0.2 0.2 0.1 0.3 0.3 0.2 0.2 0.2 gel fraction % 41 39 40 39 40 41 0 10 42 76 82 86 90 41 41 twenty four 58 59 40 38 38 apparent density g/cm ³ 0.76 0.75 0.70 0.5 0.3 0.28 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.61 0.56 0.59 0.6 0.61 0.62 0.59 0.6 thickness μm 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 adhesive layer Thickness (per side) μm 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 resin film Kind - - - - - - - - - - - - - - - - - - - - - - thickness μm 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 physical properties density g/cm ³ 0.88 0.875 0.851 0.751 0.65 0.64 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.81 0.78 0.79 0.8 0.81 0.81 0.79 0.74 thickness μm 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 Paste (both sides)/substrate thickness ratio - 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Evaluation Impact resistance high cm 40 45 54 48 43 40 44 46 60 44 43 41 40 53 45 35 48 60 45 44 40 determination - 〇 〇 〇 〇 〇 〇 〇 〇 ◎ 〇 〇 〇 〇 〇 〇 △ 〇 ◎ 〇 〇 〇 Retentivity 0.5 kg, 1 hour mm 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 determination - ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 1 kg, 1 hour mm 0.2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 fall 0.2 0 0 0 0 determination - △ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ × △ ◎ ◎ ◎ ◎ 1 kg, 2 hours mm 0.4 0 0 0 0 0 0 0 0 0 0 0 0 0 1.8 fall 0.4 0 0 0 0 determination - △ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ × × △ ◎ ◎ ◎ ◎ Rollability determination - × × × × × × × × × × × × × × × × × × × × ×

[Table 2] Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example Example twenty two twenty three twenty four 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Foam base material copolymer hard block content weight% 17 17 17 17 17 17 17 17 17 17 8 3 8 4 15 3 0 0 0 Composition (weight ratio) St - 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 91.3 93.0 91.3 - - - - - - AS-6S - - - - - - - - - - - - - - 100 100 100 - - - AA - 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 7.0 8.7 - - - - - - soft block content weight% 83 83 83 83 83 83 83 83 83 85 92 97 92 96 85 97 100 100 100 Composition (weight ratio) MA - - - - - - 50.0 75.0 49.5 49.5 50.0 49.5 49.5 49.5 - - 48.9 - - - BA - 100 100 100 100 100 50.0 25.0 49.5 49.5 50.0 49.5 49.5 49.5 97.8 97.8 49.0 94.8 81.8 91.8 2EHA - - - - - - - - - - - - - - - - - - - - St - - - - - - - - - - - - - - - - - 3.0 16.0 6.0 AA - - - - - - - - 1.0 1.0 - 1.0 1.0 1.0 2.0 2.0 2.0 2.0 2.0 2.0 HEA - - - - - - - - - - - - - - 0.2 0.2 0.1 0.2 0.2 0.2 Content of structures derived from vinyl aromatic monomers weight% 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 7.3 2.8 7.3 4.0 15.0 3.0 3.0 16.0 6.0 weight average molecular weight ten thousand 25 25 25 25 25 30 38 50 50 30 49.6 39.1 49.6 60 51 60.3 37 38 37.2 Foaming agent Kind - DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 DU40 number of copies parts by weight 3.23 3.23 3.23 2.13 3.23 3.23 3.23 3.3 3.3 3.23 3.3 3.3 3.3 2.12 2.12 3.3 2.12 2.12 3.3 Cross-linking agent number of copies parts by weight 0.2 0.2 0.2 0.2 0.2 0.3 0.25 0.15 0.15 0.3 0.15 0.5 0.15 0.3 0.3 0.3 0.25 0.25 0.5 gel fraction % 44 45 44 40 42 61 47 35 35 62 35 83 35 60 60 60 49 50 78 apparent density g/cm ³ 0.49 0.49 0.49 0.6 0.6 0.49 0.5 0.5 0.5 0.49 0.5 0.5 0.5 0.59 0.6 0.49 0.59 0.61 0.49 thickness μm 175 125 125 100 125 100 100 100 125 125 125 125 275 100 100 125 100 100 125 adhesive layer Thickness (per side) μm 50 50 75 50 75 50 50 50 75 75 75 75 25 50 50 75 50 50 75 resin film Kind - - - - PET PET - - - PET PET PET PET PET - - PET - - PET thickness μm 0 0 0 25 25 0 0 0 25 25 25 25 25 0 0 25 0 0 25 physical properties density g/cm ³ 0.73 0.73 0.73 0.82 0.73 0.74 0.74 0.74 0.74 0.74 0.74 0.74 0.74 0.79 0.8 0.74 0.79 0.81 - thickness μm 275 225 275 225 300 200 200 200 300 300 300 300 350 200 200 300 200 200 300 Paste (both sides)/substrate thickness ratio - 0.6 0.8 1.2 0.8 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 0.17 1.0 1.0 1.0 1.0 1.0 1.0 Evaluation Impact resistance high cm 80 58 60 62 69 75 70 58 60 90 83 97 90 53 58 62 43 50 48 determination - ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 〇 〇 〇 〇 〇 〇 Retentivity 0.5 kg, 1 hour mm 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 determination - ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 1 kg, 1 hour mm 0 0 0 0 0 0 0 0 0 0 0 0 0 0.3 0 0 0.4 0 0 determination - ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ △ ◎ ◎ △ ◎ ◎ 1 kg, 2 hours mm 0 0 0 0 0 0 0 0 0 0 0 0 0 0.7 0 0 1.0 0 0 determination - ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ △ ◎ ◎ × ◎ ◎ Rollability determination - × × × ◎ ◎ × × × ◎ 〇 ◎ ◎ ◎ × × 〇 × × 〇

[table 3] Comparative example Comparative example Comparative example Comparative example Comparative example 1 2 3 4 5 Foam base material copolymer hard block content weight% 17 0 0 13 0 Composition (weight ratio) St - 87.0 - - 100 - AS-6S - - - - - AA - 11.0 - - - - HEA - 2.0 - - - - soft block content weight% 83 100 100 87 100 Composition (weight ratio) MA - - - - - - BA - 100 - - - 70.0 2EHA - - - - - 27.0 St - - - - - - AA - - - - - 3.0 HEA - - - - - 0.2 PE resin - - 100 100 - - Hydrocarbon resin - - - - 100 - Content of structures derived from vinyl aromatic compound monomers weight% 14.8 0.0 0.0 13.0 0.0 weight average molecular weight ten thousand 25 - - - 71 Foaming agent Kind - - - - DU40 DU40 number of copies parts by weight 0 - - 1.23 0.5 Cross-linking agent number of copies parts by weight 0.2 - - - 0.2 gel fraction % 39 - - - apparent density g/cm ³ 1.04 0.35 0.4 0.38 0.752 thickness μm 100 100 120 100 100 adhesive layer Thickness (per side) μm 50 50 50 50 50 resin film Kind - - - - - - thickness μm 0 0 0 0 0 physical properties density g/cm ³ 1.02 0.7 0.71 0.74 0.86 thickness μm 200 200 220 200 200 Paste (both sides)/substrate thickness ratio - 1.0 1.0 0.8 1.0 1.0 Evaluation Impact resistance high cm 25 15 25 40 32 determination - △ × △ 〇 △ Retentivity 0.5kg, 1h mm 0.1 0.3 0.7 0.1 0.1 determination - △ △ △ △ △ 1 kg, 1 hour mm fall 1.5 1.4 fall 0.3 determination - × × × × △ 1 kg, 2 hours mm fall 2.2 2.0 fall 0.3 determination - × × × × △ Rollability determination - × × × × × [Industrial availability]

According to the present invention, it is possible to provide an adhesive tape that has excellent flexibility and impact resistance as well as excellent heat resistance.

1: Adhesive tape size 25 mm × 25 mm test piece 2:SUS board 3:Aluminum plate 4: Weight (0.5 kg or 1.0 kg)

[Figure 1] is a schematic diagram illustrating the holding force test of the adhesive tape.

Claims (9)

An adhesive tape having adhesive layers on both sides of a foam base material. The foam base material contains a block copolymer having at least one hard block and one soft block. The hard block It has a structure derived from a vinyl aromatic compound monomer and a structure derived from a monomer having a cross-linkable functional group, and the content of the above-mentioned structure derived from a vinyl aromatic compound monomer in the above-mentioned block copolymer is 2.5% by weight or more. 30% by weight or less, and the soft block is composed of (meth)acrylic monomers. Such as the adhesive tape of claim 1, wherein the above-mentioned monomer system with cross-linking functional groups is selected from the group consisting of hydroxyl-containing monomers, carboxyl-containing monomers, epoxy-containing monomers, amide group-containing monomers, and double bond-containing monomers. At least one of the group consisting of monomers and monomers containing triple bonds. The adhesive tape of claim 1, wherein the block copolymer contains 2.5% by weight or more and 40% by weight or less of the above-mentioned hard block. An adhesive tape having adhesive layers on both sides of a foam base material. The foam base material contains a copolymer. The copolymer has a structure derived from a vinyl aromatic compound monomer and a cross-linkable functional group. The structure of the monomer and the structure derived from the (meth)acrylic monomer, and the content of the structure derived from the vinyl aromatic compound monomer is 6% by weight or more and 30% by weight or less. The adhesive tape according to any one of claims 1 to 4, wherein the gel fraction of the above-mentioned foam base material is 90% or less. The adhesive tape according to any one of claims 1 to 4, wherein the apparent density of the above-mentioned foam base material is 0.3g/cm3 or ^more and 0.75g/cm3 ^or less. The adhesive tape according to any one of claims 1 to 4, wherein at least one side of the foam base material has a resin layer. The adhesive tape according to any one of claims 1 to 4, wherein the average cell diameter of the cells in the foam base material is 80 μm or less. For example, the adhesive tape according to any one of claims 1 to 4 is used for fixing electronic components.