KR20210079375A - adhesive tape - Google Patents

Abstract

An object of the present invention is to provide an adhesive tape having excellent flexibility and impact resistance while also excellent in heat resistance. The present invention is an adhesive tape having pressure-sensitive adhesive layers on both surfaces of a foam substrate, wherein the foam substrate contains a block copolymer having at least one hard block and one soft block, and the soft block is a (meth)acrylic type. It is an adhesive tape which is comprised from a monomer.

Description

adhesive tape

The present invention relates to an adhesive tape.

DESCRIPTION OF RELATED ART In portable electronic devices, such as a mobile phone and a portable information terminal (PDA), the adhesive tape is used for assembly (for example, patent documents 1, 2). Moreover, the adhesive tape is used also for the use which fixes vehicle-mounted electronic device components, such as an in-vehicle panel, to a vehicle body.

Japanese Patent Laid-Open No. 2009-242541 Japanese Patent Laid-Open No. 2009-258274

The high adhesive force is calculated|required by the adhesive tape used for fixing, such as portable electronic device components and in-vehicle electronic device components, and the impact resistance which does not peel even by an impact is calculated|required. On the other hand, in recent portable electronic devices, in-vehicle electronic devices, etc., since the shape tends to become more complicated with high functionalization, an adhesive tape may be attached to a step, a corner, a non-planar part, etc. and used. In such a case, the adhesive tape is required to have excellent flexibility that can follow the shape of the adherend.

As an adhesive tape excellent in the said flexibility and impact resistance, the adhesive tape using the foam base material which foamed the polyolefin resin is known. On the other hand, in recent portable electronic devices, in-vehicle electronic devices, etc., the temperature at the time of operation has become high with performance improvement and high integration. When the adhesive tape using the foam base material foamed with the polyolefin resin as mentioned above is used for such a long-term high temperature device, it may deform and peel off without being able to withstand heat completely.

An object of the present invention is to provide an adhesive tape having excellent flexibility and impact resistance while also excellent in heat resistance.

The present invention is an adhesive tape having pressure-sensitive adhesive layers on both surfaces of a foam substrate, wherein the foam substrate contains a block copolymer having at least one hard block and one soft block, and the soft block is a (meth)acrylic type. An adhesive tape consisting of a monomer.

Hereinafter, the present invention will be described in detail.

The adhesive tape of this invention has adhesive layers on both surfaces of a foam base material.

By using the foam substrate, the adhesive tape of the present invention can exhibit excellent flexibility and impact resistance. Although the said foam base material may have an open-cell structure or may have a closed-cell structure, it is preferable to have a closed-cell structure. A single layer structure may be sufficient as the said foam base material, and a multilayer structure may be sufficient as it. Moreover, as for the said adhesive layer, the same adhesive may be used for both surfaces, and a different thing may be used for it.

The said foam base material contains the block copolymer which has at least 1 or more hard block and 1 soft block.

A hard block is a block which has high cohesive force and has the role of a pseudo-crosslinking point, and a soft block refers to the flexible block which shows rubber elasticity. A block copolymer having a hard block and a soft block is difficult to be compatible with the hard block and the soft block, and takes a non-uniform phase-separation structure in which islands formed by aggregation of hard blocks in the sea of the soft block are dotted. There are cases. And it is thought that rubberiness is provided to a copolymer, and high softness|flexibility and impact resistance can be provided to the adhesive tape obtained by the degree of a hard block becoming a pseudo crosslinking point. Moreover, when a hard block has a crosslinkable functional group, it is thought that additional flexibility and impact resistance can be provided to the adhesive tape obtained. The block copolymer may have a diblock structure in which all of the hard block-soft blocks are present in the main chain, or may have a triblock structure of hard block-soft block-hard block, but more flexibility and impact resistance are improved From that point of view, it is preferable to have a triblock structure. Moreover, the graft copolymer in which a hard block and a soft block are divided into a principal chain and a side chain, and exists may be sufficient as the said block copolymer. As said graft copolymer, a styrene macromer- (meth)acryl monomer copolymer etc. are mentioned, for example.

The hard block is not particularly limited as long as it has a rigid structure, and may be a polymer of a single monomer having a rigid structure, or a copolymer composed of a plurality of monomers containing the monomer having a rigid structure. As a monomer which has the said rigid structure, a vinyl aromatic compound, the compound which has a cyclic structure, the compound etc. with a short side chain substituent are mentioned, for example. Especially, it is more preferable that the said hard block has a structure derived from a vinyl aromatic compound monomer at the point which impact resistance improves more. As said vinyl aromatic compound monomer, styrene, alphamethylstyrene, paramethylstyrene, chlorostyrene, etc. are mentioned, for example. Especially, styrene is preferable at the point which impact resistance improves further. In addition, in this specification, the structure derived from a vinyl aromatic compound monomer refers to a structure as shown to the following general formula (1) and (2).

[Formula 1]

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

When the said block copolymer has a structure derived from the said vinyl aromatic compound monomer, it is preferable that content of the structure derived from the said vinyl aromatic compound monomer in the said block copolymer is 1 weight% or more and 30 weight% or less.

When content of the structure derived from the said vinyl aromatic compound monomer is the said range, a flexibility and impact resistance can be improved more. A more preferable lower limit of the content of the structure derived from the vinyl aromatic compound monomer is 1.5 wt%, a more preferable lower limit is 2 wt%, a particularly preferable lower limit is 2.5 wt%, a more preferable upper limit is 24 wt%, and a still more preferable upper limit is 19 wt%. %, a particularly preferred upper limit is 16 wt%, and a particularly preferred upper limit is 8 wt%.

It is preferable that the said hard block has a structure derived from the monomer which has a crosslinkable functional group.

When a hard block has a crosslinkable functional group, since the rubberiness of a block copolymer becomes high by crosslinking, flexibility and impact resistance can be improved more. The crosslinkable functional group may or may not be crosslinked, and even if the structure is not crosslinked, the cohesive force in the block is improved due to the interaction between the functional groups, so that flexibility and impact resistance are improved, but it is better to be crosslinked desirable. In addition, in this specification, the structure derived from the monomer which has a crosslinkable functional group refers to a structure as shown to the following general formula (3), (4).

[Formula 2]

Here, R ² represents a substituent. The substituent R ² may contain an alkyl group, an ether group, a carbonyl group, an ester group, a carbonate group, an amide group, a urethane group, etc. as a component thereof, but a carboxyl group, a hydroxyl group, an epoxy group, a double bond, a triple bond, an amino group, an amide group , and at least one functional group selected from a nitrile group.

The monomer having the crosslinkable functional group is not particularly limited, and for example, a carboxyl group-containing monomer, a hydroxyl group-containing monomer, an epoxy group-containing monomer, a double bond-containing monomer, a triple bond-containing monomer, an amino group-containing monomer, an amide group-containing monomer, and a nitrile group Containing monomers, etc. are mentioned. Among them, at least one selected from the group consisting of hydroxyl group-containing monomers, carboxyl group-containing monomers, epoxy group-containing monomers, amide group-containing monomers, double bond-containing monomers and triple bond-containing monomers, from the viewpoint of further improving flexibility and impact resistance desirable. As a hydroxyl-containing monomer, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, etc. are mentioned. As said carboxyl group-containing monomer, (meth)acrylic acid etc. are mentioned. As an epoxy-group containing monomer, glycidyl (meth)acrylate etc. are mentioned. (meth)acrylamide etc. are mentioned as an amide group containing monomer. Examples of the double bond-containing monomer include allyl (meth) acrylate and hexanediol di (meth) acrylate. Examples of the triple bond-containing monomer include propargyl (meth)acrylate. Among these, since more excellent flexibility and impact resistance can be provided to an adhesive tape, a carboxyl group-containing monomer is preferable, a (meth)acrylic acid type monomer is more preferable, and acrylic acid is still more preferable.

When the hard block is a copolymer of the monomer having the rigid structure and the monomer having the crosslinkable functional group, the hard block contains 0.1% by weight or more and 30% by weight or less of a structure derived from the monomer having a crosslinkable functional group. it is preferable

When content of the structure derived from the monomer which has the said crosslinkable functional group in the said hard block is the said range, a flexibility and impact resistance can be improved more. A more preferable lower limit of the content of the structure derived from the monomer having a crosslinkable functional group is 0.5% by weight, a more preferable lower limit is 1% by weight, a more preferable upper limit is 25% by weight, and a still more preferable upper limit is 20% by weight.

The soft block is composed of a (meth)acrylic monomer.

When the said soft block is comprised from a (meth)acrylic-type monomer, heat resistance can be provided to the adhesive tape obtained, and even when it exposes to high temperature for a long period of time, deformation and peeling of an adhesive tape can be suppressed. The said (meth)acrylic-type monomer may be a single thing, and may use several monomers. Moreover, you may use monomers other than a (meth)acrylic-type monomer in the range which does not lose the effect of this invention.

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, but for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, Butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylic a rate, decyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, isostearyl (meth)acrylate, etc. are mentioned. Among them, methyl acrylate, ethyl acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate are preferable because it is easy to achieve both heat resistance and flexibility, and methyl acrylate, ethyl acrylate, and butyl acryl are preferable. rate, 2-ethylhexyl acrylate is more preferable.

It is preferable to use the (meth)acrylic-type monomer whose side chain carbon number is 2 or less as a (meth)acrylic-type monomer used as the raw material of the said soft block. When the (meth)acrylic-type monomer whose side chain carbon number is 2 or less is used, since entanglement of polymer chains obtained increases and cohesion force improves, heat resistance and impact resistance can be improved more. As a (meth)acrylic-type monomer whose side chain carbon number is 2 or less, methyl (meth)acrylate and ethyl (meth)acrylate are mentioned, Especially methyl acrylate and ethyl acrylate are preferable.

The minimum with preferable content of the (meth)acrylic-type monomer whose side chain carbon number in a soft block is 2 or less is 5 weight%. By including this lower limit, the cohesive force improvement effect described above becomes easy to express. A more preferable lower limit is 10 wt%, a more preferable lower limit is 20 wt%, a particularly preferable lower limit is 25 wt%, and a particularly preferable lower limit is 30 wt%. The preferable upper limit of content of the (meth)acrylic-type monomer whose side chain carbon number in a soft block is 2 or less is 90 weight%. When this upper limit is exceeded, cohesive force will become high too much, a softness|flexibility will become low, and the softness|flexibility as an adhesive tape will lose|disappear. A more preferable upper limit is 85%, a more preferable upper limit is 80% by weight, a particularly preferable upper limit is 75% by weight, and a particularly preferable upper limit is 70% by weight.

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

It is preferable that the polymerization average molecular weights of the said block copolymer are 50000-80000.

When the weight average molecular weight of a block copolymer is the said range, flexibility, impact resistance, and heat resistance can be improved more. A more preferable lower limit of the polymerization average molecular weight of the block copolymer is 75000, and a more preferable upper limit thereof is 600000. In addition, the said weight average molecular weight can be measured by GPC method, for example, "2690 Separations Module" by Water Corporation as a measuring instrument, "GPC KF-806L" by Showa Denko as a column, as a solvent Ethyl acetate can be used and it can measure on the conditions of a sample flow rate of 1 ml/min, and a column temperature of 40 degreeC.

In order to obtain the block copolymer, the raw material monomers of the hard block and the soft block are subjected to a radical reaction in the presence of a polymerization initiator to obtain a hard block and a soft block, and then reacted or copolymerized with both, or by the above method After obtaining the block, the raw material monomer for the soft block may be continuously added and copolymerized. As the method for carrying out the radical reaction, that is, the polymerization method, a conventionally known method is used, and examples thereof include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, and bulk polymerization.

The said foam base material may contain additives, such as an antistatic agent, a mold release agent, antioxidant, a weathering agent, a crystal nucleating agent, resin modifiers, such as polyolefin, polyester, polyamide, an elastomer, etc.

It is preferable that the said foam base material is 0.3 g/cm<3> or more and 0.75 g/cm<3> or less of considered density.

By making the considered density of the said foam base material into the said range, it can be set as the adhesive tape which is more excellent in flexibility and impact resistance, maintaining intensity|strength. From the viewpoint of further enhancing the strength, flexibility and impact resistance of the adhesive tape, a more preferable lower limit of the foam substrate is 0.33 g/cm 3 , a more preferable upper limit is 0.73 g/cm 3 , a more preferable lower limit is 0.35 g/cm 3 , and a more preferable upper limit is 0.71 g/cm 3 .

Here, the considered density refers to the foam base material density calculated|required from the weight of an adhesive tape when the density of the adhesive of an adhesive tape is regarded as 1.0 g/cm<3>.

In addition, the said apparent density can be measured using the electronic hydrometer (For example, the Mirage company make, "ED120T") based on JISK6767.

It is preferable that the said foam base material has a gel fraction of 90 % or less.

When the gel fraction of the said foam base material is the said range, the impact resistance of the adhesive tape obtained can be improved more. From a viewpoint of further improving the impact resistance of an adhesive tape, a more preferable upper limit of the said gel fraction is 85 %, and a more preferable upper limit is 80 %. Although the lower limit of the said gel fraction is not specifically limited, For example, it is 10 % or more, especially 20 % or more, Especially 35 % or more. The gel fraction may be controlled by crosslinking at least one of the hard block and the soft block. In addition, the said gel fraction can be measured by the following method.

Only 0.1 g of a foam base material is taken out from the obtained adhesive tape, it is made to immerse in 50 ml of ethyl acetate, and it shakes on condition of the temperature of 23 degree|times and 120 rpm with a shaker for 24 hours. After shaking, using a metal mesh (net size #200 mesh), ethyl acetate and ethyl acetate were absorbed to separate the swollen foam substrate. The foam base material after isolation|separation is dried under 110 degreeC conditions for 1 hour. The weight of the foam substrate including the metal mesh after drying is measured, and the gel fraction of the foam substrate is calculated using the following formula.

Gel fraction (wt%) = 100 x (W1-W2)/W0

(W0: initial weight of foam substrate, W1: weight of foam substrate including metal mesh after drying, W2: initial weight of metal mesh)

As for the said foam base material, it is preferable that the crosslinking structure is formed between the main chains of resin which comprises the said foam base material by adding a crosslinking agent. By forming a crosslinked structure between the main chains of the resin constituting the foam substrate, the intermittent peeling stress can be dispersed, and the heat resistance and impact resistance of the adhesive tape can be further improved. The said crosslinking agent is not specifically limited, According to the functional group which resin which comprises the said foam base material has, it can select suitably. Specifically, an isocyanate type crosslinking agent, an aziridine type crosslinking agent, an epoxy type crosslinking agent, a metal chelate type crosslinking agent, etc. are mentioned, for example. Among them, an epoxy-based cross-linking agent or an isocyanate-based cross-linking agent is preferable from the viewpoint of cross-linking a resin having an alcoholic hydroxyl group or a carboxyl group that can further improve flexibility and impact resistance. Moreover, the said isocyanate type crosslinking agent bridge|crosslinks between the alcoholic hydroxyl group and carboxyl group in resin which comprises the said foam base material, and the isocyanate group of a crosslinking agent. Moreover, the said epoxy-type crosslinking agent bridge|crosslinks between the carboxyl group in resin which comprises the said foam base material, and the epoxy group of a crosslinking agent.

The amount of the crosslinking agent to be added is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 7 parts by weight, based on 100 parts by weight of the resin used as the main component of the foam substrate.

The foam substrate preferably has an average cell diameter of 80 µm or less.

When the average cell diameter of a foam base material is the said range, the balance of the intensity|strength, softness|flexibility, and impact resistance of the adhesive tape obtained can be raised more.

It is more preferable that it is 60 micrometers or less, and, as for the average cell diameter of the said foam base material, it is still more preferable that it is 55 micrometers or less. Although the lower limit of the average cell diameter of the said foam base material is not specifically limited, From a viewpoint of ensuring tape flexibility, it is preferable that it is 20 micrometers or more, and it is more preferable that it is 30 micrometers or more.

In addition, the said average cell diameter can be measured with the following method.

First, the foam substrate is cut in a square of 50 mm, immersed in liquid nitrogen for 1 minute, and then cut using a razor blade in a plane perpendicular to the thickness direction of the foam substrate. Then, using a digital microscope (for example, "VHX-900" manufactured by Keyence Corporation), an enlarged photograph of the cut surface is taken at a magnification of 200 times, and all cells present in the range of thickness × 2 mm The longest cell diameter (the diameter of the bubble) is measured. This operation is repeated 5 times, and the average cell diameter is calculated by averaging all the obtained cell diameters.

Although the thickness of the said foam base material is not specifically limited, A preferable lower limit is 40 micrometers, and a preferable upper limit is 2900 micrometers. By making the thickness of the said foam base material into the said range, the adhesive tape of this invention can be used suitably for fixing of a portable electronic device component, an on-vehicle electronic device component, etc. From the viewpoint of being more preferably used for fixing the parts, etc., the more preferable lower limit of the thickness of the foam base material is 60 µm, the more preferred upper limit is 1900 µm, the more preferred lower limit is 80 µm, and the more preferred upper limit is 1400 µm, especially A preferable lower limit is 100 μm, and a particularly preferable upper limit is 1000 μm.

The said foam base material should just have a cell structure, and a manufacturing method is not specifically limited. As a manufacturing method, the method of manufacturing the said foam base material by the action|action of a foaming gas, and the method of manufacturing by mix|blending a hollow sphere in a raw material matrix, for example is mentioned, for example. Among them, the foam produced by the latter method is called a syntactic foam, and from the viewpoint of more excellent impact resistance and heat resistance, the foam substrate is preferably a syntactic foam. By using the foam base material as a syntactic foam, a closed-cell foam having a uniform size distribution of the foam cells is obtained, so that the density of the entire foam base material becomes more constant, and the impact resistance can be further improved. Moreover, compared with other foams, since it is hard to produce irreversible disintegration under high temperature and high pressure, a syntactic foam shows higher heat resistance. Examples of the syntactic foam include those having a foamed structure made of hollow inorganic particles and those having a foamed structure made of hollow organic particles. From the viewpoint of flexibility, a syntactic foam having a foamed structure made of hollow organic particles is preferable.

As said hollow organic microparticles|fine-particles, Expancel DU series (made by Nippon Fillite), Advancell EM series (made by Sekisui Chemical Industries, Ltd.) etc. are mentioned, for example. Among them, expancel 461-20 (average cell diameter after foaming under optimal conditions of 20 µm), expancel 461-40 (after foaming under optimal conditions), in that it is easy to design the cell diameter after foaming into a more effective region. Average cell diameter 40 µm), Expancel 043-80 (average cell diameter after foaming under optimum conditions of 80 µm), and Advancel EML101 (average cell diameter after foaming under optimum conditions of 50 µm) are preferred.

A foaming agent in the case where the foam base material is formed of a foam other than the syntactic foam is not particularly limited, and a conventionally known foaming agent such as a thermal decomposition foaming agent may be used.

The said adhesive layer is not specifically limited, For example, an acrylic adhesive layer, a rubber adhesive layer, a urethane adhesive layer, a silicone adhesive layer, etc. are mentioned. Especially, since it is excellent in heat resistance and can adhere|attach to a wide type of to-be-adhered body, the acrylic adhesive layer containing an acrylic copolymer is preferable.

The acrylic copolymer constituting the acrylic pressure-sensitive adhesive layer is obtained by copolymerizing a monomer mixture containing butyl acrylate and/or 2-ethylhexyl acrylate from the viewpoint of improving the adhesion at low temperatures because the initial tack is improved. It is preferable to obtain Especially, what is obtained by copolymerizing the monomer mixture containing butyl acrylate and 2-ethylhexyl acrylate is more preferable.

A preferable lower limit of the content of the butyl acrylate in the total monomer mixture is 40% by weight, and a preferable upper limit thereof is 80% by weight. By making content of the said butyl acrylate into the said range, high adhesive force and tackiness can be made compatible.

A preferable lower limit of the content of the 2-ethylhexyl acrylate in the total monomer mixture is 10% by weight, a preferable upper limit is 100% by weight, a more preferable lower limit is 30% by weight, a more preferable upper limit is 80% by weight, and a more preferable lower limit is 50% by weight. % by weight, and a more preferable upper limit is 60% by weight. By making content of the said 2-ethylhexyl acrylate into the said range, high adhesive force can be exhibited.

The said monomer mixture may contain the other polymerizable monomer which can be copolymerized other than butyl acrylate and 2-ethylhexyl acrylate as needed. Examples of the copolymerizable other polymerizable monomer include (meth)acrylic acid alkyl esters having 1 to 3 carbon atoms in the alkyl group, (meth)acrylic acid alkyl esters having 13 to 18 carbon atoms in the alkyl group, and functional monomers. have.

Examples of the (meth)acrylic acid alkylester having 1 to 3 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and isopropyl (meth)acrylate. can As (meth)acrylic-acid alkylester whose carbon number of the said alkyl group is 13-18, tridecyl methacrylate, stearyl (meth)acrylate, etc. are mentioned, for example. As the functional monomer, for example, (meth) acrylic acid hydroxyalkyl, glycerin dimethacrylate, (meth) acrylate glycidyl, 2-methacryloyloxyethyl isocyanate, (meth) acrylic acid, itaconic acid, Maleic anhydride, crotonic acid, maleic acid, fumaric acid, etc. are mentioned.

In order to copolymerize the monomer mixture to obtain the acrylic copolymer, the monomer mixture may be subjected to a radical reaction in the presence of a polymerization initiator. A method for radically reacting the monomer mixture, that is, a polymerization method, a conventionally known method is used, for example, solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization, etc. have.

As for the weight average molecular weight (Mw) of the said acrylic copolymer, a preferable minimum is 400,000, and a preferable upper limit is 1.5 million. By making the weight average molecular weight of the said acrylic copolymer into the said range, high adhesive force can be exhibited. From a viewpoint of the further improvement of adhesive force, a more preferable minimum of the said weight average molecular weight is 500,000, and a more preferable upper limit is 1.4 million.

In addition, a weight average molecular weight (Mw) is a weight average molecular weight of standard polystyrene conversion by GPC(Gel Permeation Chromatography: 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. When Mw/Mn is 10.0 or less, the ratio of a low molecular component is suppressed, the said adhesive layer softens under high temperature, and it is suppressed that bulk strength becomes low and adhesive strength falls. From the same viewpoint, the more preferable upper limit of Mw/Mn is 5.0, and the more preferable upper limit is 3.0.

The said adhesive layer may contain tackifying resin.

Examples of the tackifying resin include rosin ester-based resins, hydrogenated rosin-based resins, terpene-based resins, terpene phenol-based resins, coumarone indene-based resins, alicyclic saturated hydrocarbon-based resins, C5-based petroleum resins, and C9-based petroleum resins. Resin, C5-C9 copolymer type petroleum resin, etc. are mentioned. These tackifying resins may be used independently and may use 2 or more types together.

Although content of the said tackifying resin is not specifically limited, A preferable minimum with respect to 100 weight part of resin (for example, acrylic copolymer) used as a main component of the said adhesive layer is 10 weight part, A preferable upper limit is 60 weight part. When content of the said tackifying resin is 10 weight part or more, the fall of the adhesive force of the said adhesive layer can be suppressed. When content of the said tackifying resin is 60 weight part or less, the fall of the adhesive force or tackiness by the said adhesive layer becoming hard can be suppressed.

As for the said adhesive layer, it is preferable that the crosslinking structure is formed between the main chains of resin (for example, the said acrylic copolymer, the said tackifying resin, etc.) which comprises the said adhesive layer by adding a crosslinking agent. The crosslinking agent is not particularly limited, and examples thereof include an isocyanate-based crosslinking agent, an aziridine-based crosslinking agent, an epoxy-based crosslinking agent, and a metal chelate-type crosslinking agent. Especially, an isocyanate type crosslinking agent is preferable. When the isocyanate-based crosslinking agent is added to the pressure-sensitive adhesive layer, the isocyanate group of the isocyanate-based crosslinking agent and the alcoholic hydroxyl group in the resin constituting the pressure-sensitive adhesive layer (eg, the acrylic copolymer, the tackifying resin, etc.) react, and the pressure-sensitive adhesive layer This is crosslinked. When a crosslinked structure is formed between the main chains of the resin constituting the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer can disperse the intermittent peeling stress, and the adhesive force of the pressure-sensitive adhesive tape is further improved.

0.01-10 weight part is preferable with respect to 100 weight part of resin (for example, the said acrylic copolymer) used as a main component of the said adhesive layer, and, as for the addition amount of the said crosslinking agent, 0.1-7 weight part is more preferable.

The said adhesive layer may contain a silane coupling agent in order to improve adhesive force. The said silane coupling agent is not specifically limited, For example, epoxysilanes, acrylsilanes, methacrylsilanes, aminosilanes, isocyanate silanes, etc. are mentioned.

The said adhesive layer may contain a coloring material for the purpose of providing light-shielding property. The said colorant is not specifically limited, For example, carbon black, aniline black, titanium oxide, etc. are mentioned. Among them, carbon black is preferable because it is relatively inexpensive and chemically stable.

The said adhesive layer may contain conventionally well-known microparticles|fine-particles and additives, such as inorganic microparticles|fine-particles, electrically conductive microparticles|fine-particles, antioxidant, a foaming agent, an organic filler, and an inorganic filler, as needed.

Although the thickness of the said adhesive layer is not specifically limited, A preferable minimum is 0.01 mm and a preferable upper limit is 0.1 mm. By making the thickness of the said adhesive layer into the said range, the adhesive tape of this invention can be used suitably for fixing of a portable electronic device component, an on-vehicle electronic device component, etc. From a viewpoint which can be used more preferably for fixing of the said component etc., a more preferable minimum of the thickness of the said adhesive layer is 0.015 mm, and a more preferable upper limit is 0.09 mm.

It is preferable that the adhesive tape of this invention has a resin layer in at least one surface of the said foam base material.

By having the said resin layer, since the intensity|strength of the adhesive tape obtained improves, impact resistance can be improved more and durability (tumble property) at the time of giving an impact especially repeatedly can be improved. Although the said resin layer may be formed in the single side|surface of the said foam base material, or it may be provided in both surfaces, it is preferable that it is provided in the single side|surface of the foam base material.

It is preferable that resin which comprises the said resin layer has heat resistance. Examples of the resin constituting the resin layer having heat resistance include polyester resins such as polyethylene terephthalate, acrylic resins, silicone resins, phenol resins, polyimides, and polycarbonates. Especially, since the adhesive tape excellent in a softness|flexibility is obtained, an acrylic resin and a polyester resin are preferable, and a polyethylene terephthalate is more preferable.

The resin layer may be colored. By coloring the said resin layer, light-shielding property can be provided to an adhesive tape.

The method of coloring the resin layer is not particularly limited, and for example, a method of kneading particles or fine air bubbles such as carbon black or titanium oxide with the resin constituting the resin layer, and applying ink to the surface of the resin layer how to do it, etc.

The said resin layer may contain conventionally well-known microparticles|fine-particles and additives, such as inorganic microparticles|fine-particles, conductive microparticles|fine-particles, a plasticizer, a tackifier, a ultraviolet absorber, antioxidant, a foaming agent, an organic filler, and an inorganic filler, as needed.

Although the thickness of the said resin layer is not specifically limited, A preferable minimum is 5 micrometers, and a preferable upper limit is 100 micrometers. By making the thickness of the said resin layer into the said range, the handleability of an adhesive tape and impact resistance can be made compatible. A more preferable lower limit of the thickness of the resin layer is 10 µm, and a more preferable upper limit is 70 µm, from the viewpoint of further making handleability and impact resistance compatible.

The adhesive tape of this invention may have other layers other than the said foam base material, the said adhesive layer, and the said resin layer as needed.

As for the adhesive tape of this invention, it is preferable that ratio (adhesive layer thickness/foam base material thickness) of the thickness of an adhesive layer and the thickness of a foam base material is 0.1 or more and 2 or less. When ratio of the thickness of an adhesive layer and a foam base material is the said range, since the intensity|strength of the whole adhesive tape obtained improves, impact resistance can be improved more. It is more preferable that it is 0.15 or more, and, as for ratio of the thickness of the said adhesive layer, and the thickness of a foam base material, it is more preferable that it is 1.2 or less. In addition, the thickness of the said adhesive layer points out the sum total of the thickness of the adhesive layer of both surfaces.

Although the thickness of the adhesive tape of this invention is not specifically limited, A preferable minimum is 0.04 mm, a more preferable minimum is 0.05 mm, and a preferable upper limit is 2 mm, and a more preferable upper limit is 1.5 mm. By making the thickness of the adhesive tape of this invention into the said range, it can be set as the adhesive tape excellent in handleability.

It does not specifically limit as a manufacturing method of the adhesive tape of this invention, For example, the following methods are mentioned. First, a pressure-sensitive adhesive solution is coated on a release film and dried to form an pressure-sensitive adhesive layer, and a second pressure-sensitive adhesive layer is formed in the same manner. Then, a non-foamed substrate is prepared by the above method, and the resin layer is laminated on the non-foamed substrate to form a laminate. Then, the obtained adhesive layer is pasted together on both surfaces of the obtained laminated body, and an unfoamed base material is foamed by heating, and an adhesive tape is manufactured.

Although the shape of the adhesive tape of this invention is not specifically limited, Rectangle, a frame shape, a circular shape, an ellipse, a donut shape, etc. are mentioned.

The adhesive tape of this invention can exhibit the outstanding flexibility, impact resistance, and heat resistance by using the said block copolymer as a foam base material. On the other hand, as a result of the study conducted by the present inventors, the foam substrate includes a structure derived from the vinyl aromatic compound monomer, a structure derived from a monomer having a crosslinkable functional group, and a structure derived from the (meth)acrylic monomer It was found that excellent flexibility, impact resistance and heat resistance can be exhibited even in the case of a random copolymer. This is thought to be because the same interaction as the phase-separated structure is acting on an extremely small scale such as a nano level or a molecular level. In addition, in this specification, the structure derived from a (meth)acrylic-type monomer refers to a structure as shown to the following general formula (5), (6).

[Formula 3]

Here, R ³ represents a side chain. As side chain R ³ , a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, a dodecyl group, a lauryl group, isoste An aryl group etc. are mentioned.

Therefore, as an adhesive tape having pressure-sensitive adhesive layers on both surfaces of a foam substrate, the foam substrate contains a copolymer, and the copolymer has a structure derived from a vinyl aromatic compound monomer, a structure derived from a monomer having a crosslinkable functional group, and a structure derived from a monomer having a crosslinkable functional group. And the adhesive tape which has a structure derived from a (meth)acrylic-type monomer is also one of this invention.

It does not restrict|limit especially as said copolymer, A block copolymer and a random copolymer are mentioned.

Among them, a soft block (a block containing a structure derived from the (meth)acrylic monomer) and a hard block (a block containing a structure derived from the vinyl aromatic compound monomer) have a non-uniform phase-separation structure, and the hard block A block copolymer is preferable from a viewpoint that rubberiness is provided to a copolymer and high softness|flexibility and impact resistance can be provided to the adhesive tape obtained by becoming this pseudo-crosslinking point. Examples of the block copolymer include a diblock copolymer, a triblock copolymer, and a graft copolymer. From the viewpoint of forming the phase separation, a diblock copolymer and a triblock copolymer are preferable, and a triblock copolymer is more preferable. Do.

When the said copolymer is a block copolymer, it is preferable that a block copolymer contains 1 weight% or more and 40 weight% or less of the said hard block. By making content of the said hard block into the said range, the foam base material excellent in flexibility, impact resistance, and heat resistance can be formed. From the viewpoint of further enhancing flexibility, impact resistance and heat resistance, the more preferable lower limit of the content of the hard block is 2% by weight, the more preferable lower limit is 2.5% by weight, the more preferable lower limit is 3% by weight, and the more preferable upper limit is 35%, furthermore A preferable upper limit is 30%, a more preferable upper limit is 26 weight%, a more preferable upper limit is 20 weight%, a particularly preferable upper limit is 17 weight%, and a particularly preferable upper limit is 8 weight%.

When the said copolymer is a block copolymer, it is preferable that the polymerization average molecular weights of a block copolymer are 50000-80000.

When the weight average molecular weight of a block copolymer is the said range, flexibility, impact resistance, and heat resistance can be improved more. A more preferable lower limit of the polymerization average molecular weight of the block copolymer is 75000, and a more preferable upper limit thereof is 600000.

In order to obtain the block copolymer, the raw material monomers of the hard block and the soft block are subjected to a radical reaction in the presence of a polymerization initiator to obtain a hard block and a soft block, and then reacted or copolymerized with both, or the hard block by the above method After obtaining the block, the raw material monomer for the soft block may be continuously added and copolymerized. As the method for carrying out the radical reaction, that is, the polymerization method, a conventionally known method is used, and examples thereof include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, and bulk polymerization.

It does not specifically limit about the said vinyl aromatic compound monomer, For example, styrene, alphamethylstyrene, paramethylstyrene, chlorostyrene, etc. are mentioned. Especially, styrene is preferable at the point which impact resistance improves further.

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

The monomer having the crosslinkable functional group is not particularly limited, and for example, a carboxyl group-containing monomer, a hydroxyl group-containing monomer, an epoxy group-containing monomer, a double bond-containing monomer, a triple bond-containing monomer, an amino group-containing monomer, an amide group-containing monomer, and a nitrile group Containing monomers, etc. are mentioned. Among them, at least one selected from the group consisting of hydroxyl group-containing monomers, carboxyl group-containing monomers, epoxy group-containing monomers, amide group-containing monomers, double bond-containing monomers and triple bond-containing monomers, from the viewpoint of further improving flexibility and impact resistance desirable. As a hydroxyl-containing monomer, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, etc. are mentioned. As said carboxyl group-containing monomer, (meth)acrylic acid etc. are mentioned. As an epoxy-group containing monomer, glycidyl (meth)acrylate etc. are mentioned. (meth)acrylamide etc. are mentioned as an amide group containing monomer. Examples of the double bond-containing monomer include allyl (meth) acrylate and hexanediol di (meth) acrylate. Examples of the triple bond-containing monomer include propargyl (meth)acrylate. Among these, since more excellent flexibility and impact resistance can be provided to an adhesive tape, a carboxyl group-containing monomer is preferable, a (meth)acrylic acid type monomer is more preferable, and acrylic acid is still more preferable.

It is preferable that content of the structure derived from the monomer which has the said crosslinkable functional group in the said copolymer is 0.1 weight% or more and 30 weight% or less. A more preferable lower limit is 0.5 weight%, a more preferable lower limit is 1 weight%, a more preferable upper limit is 25 weight%, and a more preferable upper limit is 20 weight%.

The (meth)acrylic monomer is not particularly limited, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (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, isostearyl (meth)acrylate, and the like. Among them, methyl acrylate, ethyl acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate are preferable because it is easy to achieve both heat resistance and flexibility, and methyl acrylate, ethyl acrylate, and butyl acryl are preferable. rate, 2-ethylhexyl acrylate is more preferable. The said (meth)acrylic-type monomer may be a single thing, and may use several monomers. Moreover, you may use monomers other than a (meth)acrylic-type monomer in the range which does not lose the effect of this invention.

Although content of the structure derived from the said (meth)acrylic-type monomer in the said copolymer will not be specifically limited if the effect of this invention is exhibited, It is preferable that it is 30 weight% or more and 99 weight% or less, 40 weight% or more and 98 weight% % or less, and more preferably 50 wt% or more and 97 wt% or less.

The foam substrate is preferably a syntactic foam having a foamed structure made of hollow organic fine particles.

Examples of the hollow organic fine particles constituting the syntactic foam include Expancel DU series (manufactured by Nippon Fillite Co., Ltd.) and Advancel EM series (manufactured by Sekisui Chemical Industry Co., Ltd.). Among them, Expancel 461-20 (average cell diameter after foaming under optimum conditions of 20 µm), Expancel 461-40 (average after foaming under optimum conditions), in that it is easy to design the cell diameter after foaming into a region with high effect. Cell diameter 40 µm), Expancel 043-80 (average cell diameter after foaming under optimal conditions of 80 µm), and Advancel EML101 (average cell diameter after foaming under optimal conditions of 50 µm) are preferred.

The foam substrate may use the same additives as the foam layer of the adhesive tape using the block copolymer.

The foam base material preferably has a deemed density of 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, and still more preferably 0.35 g/cm 3 or more and 0.71 g/cm 3 or less. Do.

It is preferable that the gel fraction of the said foam base material is 90 % or less, It is more preferable that it is 85 % or less, It is still more preferable that it is 80 % or less. Although the lower limit of the said gel fraction is not specifically limited, For example, it is 10 % or more, especially 20 % or more, Especially 35 % or more.

The foam substrate preferably has an average cell diameter of 80 µm or less, more preferably 60 µm or less, and still more preferably 55 µm or less. It is preferable that the average cell diameter of the said bubble is 20 micrometers or more.

The thickness of the foam substrate is not particularly limited, but a preferred lower limit is 40 µm, a more preferred lower limit is 60 µm, a more preferred lower limit is 80 µm, a particularly preferred lower limit is 100 µm, a preferred upper limit is 2900 µm, and a more preferred upper limit is 1900 µm. , a more preferable upper limit is 1400 μm, and a particularly preferable upper limit is 1000 μm.

As a method for producing the copolymer, for example, a solution obtained by mixing a vinyl aromatic compound monomer, a monomer having a crosslinkable functional group, a (meth)acrylic monomer, and other monomers if necessary is subjected to a radical reaction in the presence of a polymerization initiator. you should do it As a method for radical reaction, a conventionally well-known method is used, For example, solution polymerization (boiling-point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, block polymerization, etc. are mentioned.

The manufacturing method of the foam substrate is not particularly limited, and for example, first, a foaming agent is added to the solution of the copolymer and mixed, coated in a desired shape, dried to form a non-foamed substrate, and then the obtained non-foamed substrate heating to foam the foaming agent. Moreover, when the said foam base material is a syntactic foam, the method of adding and mixing the said hollow organic microparticles|fine-particles to the solution of the said copolymer, coating in a desired shape, drying, etc. are mentioned.

It is preferable that the said adhesive tape has a resin layer in at least one surface of the said foam base material.

The resin constituting the resin layer preferably has heat resistance, and examples thereof include polyester-based resins such as polyethylene terephthalate, acrylic resins, silicone resins, phenolic resins, polyimides, and polycarbonates. Especially, since the adhesive tape excellent in a softness|flexibility is obtained, an acrylic resin and a polyester resin are preferable, and a polyethylene terephthalate is more preferable.

Although the thickness of the said resin layer is not specifically limited, A preferable lower limit is 5 micrometers, a more preferable lower limit is 10 micrometers, a preferable upper limit is 100 micrometers, A more preferable upper limit is 70 micrometers.

As the said adhesive layer, the thing similar to the adhesive layer of the adhesive tape using the said block copolymer can be used.

Although the use of the adhesive tape of the present invention is not particularly limited, since it is excellent in flexibility, impact resistance and heat resistance, it can be preferably used as an impact-resistant adhesive tape for fixing electronic components such as portable electronic device components and vehicle-mounted electronic device components. have. The adhesive tape of this invention used for fixing such an electronic component is also one of this invention.

ADVANTAGE OF THE INVENTION According to this invention, while having the outstanding flexibility and impact resistance, the adhesive tape excellent also in heat resistance can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram explaining the holding force test of an adhesive tape.

The embodiments of the present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples.

(Example 1)

(1) Preparation of non-foam base material

0.902 g of 1,6-hexanedithiol, 1.83 g of carbon disulfide, and 11 ml of dimethylformamide were put into a two-necked flask, followed by stirring at 25°C. 2.49 g of triethylamine was dripped at this over 15 minutes, and it stirred at 25 degreeC for 3 hours. Then, 2.75 g of methyl- (alpha)-bromophenylacetic acid was dripped over 15 minutes, and it stirred at 25 degreeC for 4 hours. Then, 100 ml of extraction solvent (n-hexane:ethyl acetate=50:50) and 50 ml of water were added to the reaction liquid, and liquid separation extraction was carried out. The organic layers obtained by the liquid separation extraction of the 1st time and the 2nd time were mixed, and it wash|cleaned in this order with 50 ml of 1 M hydrochloric acid, 50 ml of water, and 50 ml of saturated saline. After the washing organic layer was dried by adding sodium sulfate, the sodium sulfate was filtered, and the filtrate was concentrated with an evaporator to remove the organic solvent. The RAFT agent was obtained by refine|purifying the obtained concentrate by silica gel column chromatography.

91.3 g of styrene (St), 8.7 g of acrylic acid (AA), 1.9 g of RAFT, and 0.2 g of 2,2'-azobis(2-methylbutyronitrile) (ABN-E) were put into a two-necked flask and it heated up at 85 degreeC, replacing the inside of a flask with nitrogen gas. Then, it stirred at 85 degreeC for 6 hours, and performed polymerization reaction (1st stage reaction).

After completion of the reaction, 4000 g of n-hexane was added into the flask and stirred to precipitate a reaction product, unreacted monomers (St, AA) and a RAFT agent were filtered off, and the reaction product was dried under reduced pressure at 70° C. to obtain a copolymer. (hard block) was obtained.

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 were put into a two-neck flask, and the inside of the flask was substituted with nitrogen gas. It heated up to 85 degreeC. Then, it stirred at 85 degreeC for 6 hours, polymerization reaction was performed (2nd stage reaction), and the reaction liquid containing the block copolymer formed from a hard block and a soft block was obtained. In addition, the compounding quantity of a mixture (soft block) and a hard block was made into the quantity from which content of the hard block in the block copolymer obtained will be 17 weight%.

A part of the reaction solution is collected, 4000 g of n-hexane is added thereto, stirred to precipitate a reaction product, unreacted monomer (BA) and a solvent are filtered off, and the reaction product is dried under reduced pressure at 70° C. to block The copolymer was taken out from the reaction solution. About the obtained block copolymer, when the weight average molecular weight was measured by GPC method, it was 250,000. "2690 Separations Module" manufactured by Water Corporation as a measuring instrument, "GPC KF-806L" manufactured by Showa Denko Co., Ltd. as a column, and ethyl acetate as a solvent, sample flow rate 1 ml/min, column temperature of 40°C measured.

The obtained block copolymer was dissolved in ethyl acetate so that the solid content was 35%, and with respect to 100 parts by weight of the block copolymer A, Expancel 461-40 (manufactured by Nippon Fillite Co., Ltd., denoted as DU40 in the table) 0.5 as a foaming agent By weight, 0.2 parts by weight of Tetrad C (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a crosslinking agent was added, followed by sufficient stirring to obtain a base solution. The non-foamed base material was obtained by coating the obtained base material solution on the release process surface of the 50 micrometers polyethylene terephthalate (PET) film which performed the release process on one side, and drying it for 7 minutes at 90 degreeC. The thickness of the non-foam base material was adjusted to be 100 µm when the non-foam base material was heated at 130°C for 1 minute.

(2) Preparation of adhesive solution

52 parts by weight of ethyl acetate was put into a reactor equipped with a thermometer, a stirrer, and a cooling tube to replace nitrogen, and then the reactor was heated to initiate reflux. After ethyl acetate boiled, 0.08 weight part of azobisisobutyronitrile was thrown in 30 minutes afterward as a polymerization initiator. A monomer mixture comprising 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 is added dropwise evenly and gradually over 1 hour and 30 minutes. and reacted. After 30 minutes of completion of the dropwise addition, 0.1 parts by weight of azobisisobutyronitrile was added, polymerization was carried out for an additional 5 hours, and ethyl acetate was added in the reactor to cool while diluting to obtain a solution of an acrylic random copolymer having a solid content of 40% by weight. .

As a result of measuring the weight average molecular weight of the obtained acrylic random copolymer by GPC method using "2690 Separations Model" manufactured by Water as a column, it 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 a polymerization rosin ester having a softening point of 150°C, 10 parts by weight of a terpene phenol having a softening point of 145°C, and 10 parts by weight of a rosin ester having a softening point of 70°C were added. Further, 30 parts by weight of ethyl acetate (manufactured by Fuji Chemical Co., Ltd.) and 3.0 parts by weight of an isocyanate-based crosslinking agent (Colonate L45 manufactured by Tosoh Corporation) were added and stirred to obtain a pressure-sensitive adhesive solution.

(3) Preparation of adhesive tape

On the release-treated surface of a 50 µm polyethylene terephthalate (PET) film subjected to a release treatment on one side, the obtained pressure-sensitive adhesive solution was applied with a doctor knife so that the dry film had a thickness of 50 µm, and then heated at 110° C. for 5 minutes. The solution was dried to obtain an adhesive layer. Next, one more adhesive layer was manufactured by the same operation, and two adhesive layers were obtained. Then, the release film was peeled from the non-foaming body base material obtained above, the two adhesive layers obtained on both surfaces of the non-foaming body base material were bonded together, respectively, and it left still in a 40 degreeC environment for 48 hours. The base material was foamed by taking out from 40 degreeC environment after 48 hours, and heating 130 degreeC for 1 minute, and the adhesive tape was obtained.

(4) Measurement of tape density

The density of the obtained adhesive tape was measured using the electronic hydrometer (The Mirage company make, ED120T).

(5) Measurement of considered density of foam substrate

The density of the obtained foam base material was measured using the electronic hydrometer (The Mirage company make, ED120T) based on JISK-6767. From this result, the considered density of the foam base material was calculated by considering the density of an adhesive as 1.0 g/cm<3>.

(6) Measurement of the gel fraction of the foam substrate

Only 0.1 g of the foam base material was taken out from the obtained adhesive tape, it was made to be immersed in 50 ml of ethyl acetate, and it shook on the conditions of the temperature of 23 degrees and 120 rpm with a shaker for 24 hours. After shaking, using a metal mesh (net size #200 mesh), ethyl acetate and ethyl acetate were absorbed to separate the swollen foam substrate. The foam base material after isolation|separation was dried on 110 degreeC conditions for 1 hour. The weight of the foam substrate including the metal mesh after drying was measured, and the gel fraction of the foam substrate was calculated using the following formula.

Gel fraction (wt%) = 100 x (W1-W2)/W0

(W0: initial weight of foam substrate, W1: weight of foam substrate including metal mesh after drying, W2: initial weight of metal mesh)

(Examples 2 to 24, 27 to 29)

Except having made the composition and thickness of a foam base material and the thickness of an adhesive layer like Tables 1 and 2, it carried out similarly to Example 1, and obtained the adhesive tape. In addition, in Example 20, the base material was foamed by heating at 150 degreeC for 1 minute. About the obtained adhesive tape, each measurement was performed similarly to Example 1. The raw materials in a table|surface are as follows.

MA: methyl acrylate

AA: acrylic acid

HEA: Acrylic acid-2-hydroxyethyl

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 pressure-sensitive adhesive layer are shown in Table 2, and the base solution was coated on a 25 µm-thick polyethylene terephthalate (PET) sheet (E5007, manufactured by Toyobo Corporation), which is a resin layer. It carried out similarly to 1, and obtained the adhesive tape. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Examples 26, 30 to 34)

Except having made the composition and thickness of a foam base material and the thickness of an adhesive layer like Table 2, it carried out similarly to Example 25, and obtained the adhesive tape. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Example 35)

(1) Preparation of unfoamed substrate

52 parts by weight of ethyl acetate was put into a reactor equipped with a thermometer, a stirrer, and a cooling tube to replace nitrogen, and then the reactor was heated to initiate reflux. After ethyl acetate was boiled, 0.08 parts by weight of azobisisobutyronitrile as a polymerization initiator was added 30 minutes later. Herein, 93.888 parts by weight of butyl acrylate, 4 parts by weight of styrene macromer (AS-6S in the table, manufactured by Toa Synthesis), 1.92 parts by weight of acrylic acid, and 0.192 parts by weight of acrylic acid-2-hydroxyethyl 1 Over time 30 minutes, it was made to react by dripping evenly and gradually. After 30 minutes of completion of the dropwise addition, 0.1 parts by weight of azobisisobutyronitrile was added, polymerization was carried out for an additional 5 hours, and ethyl acetate was added in the reactor and cooled while diluting to obtain a solution of an acrylic graft copolymer having a solid content of 40% by weight. .

About the obtained acrylic graft copolymer, when the weight average molecular weight was measured by GPC method, it was 600,000. "2690 Separations Module" manufactured by Water Corporation as a measuring instrument, "GPC KF-806L" manufactured by Showa Denko Co., Ltd. as a column, and ethyl acetate as a solvent, sample flow rate 1 ml/min, column temperature of 40°C measured.

The obtained graft copolymer was dissolved in ethyl acetate so that the solid content was 35%, and with respect 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 of Tetrad C as a crosslinking agent were added. Furthermore, it fully stirred and obtained the base material solution. The obtained base material solution was coated on the release-treated surface of a 50 µm polyethylene terephthalate (PET) film subjected to a release treatment on one side, and dried at 90° C. for 7 minutes to obtain a non-foamed base material comprising a graft copolymer. The thickness of the non-foam base material was adjusted to be 100 µm when the non-foam base material was heated at 130°C for 1 minute.

(2) Preparation of adhesive tape

Except having used the non-foaming base material which consists of the obtained graft copolymer, it carried out similarly to Example 1, and obtained the adhesive tape. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Example 36)

Except having made content of a hard block component and a soft block component like Table 2, it carried out similarly to Example 35, and obtained the adhesive tape. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Example 37)

An unfoamed base material comprising 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 shown in Table 2. Next, except having made the thickness of an adhesive layer like Table 2, it carried out similarly to Example 25, and obtained the adhesive tape. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Example 38)

(1) Preparation of unfoamed substrate

52 parts by weight of ethyl acetate was put into a reactor equipped with a thermometer, a stirrer, and a cooling tube to replace nitrogen, and then the reactor was heated to initiate reflux. After ethyl acetate was boiled, 0.08 parts by weight of azobisisobutyronitrile as a polymerization initiator was added 30 minutes later. A monomer mixture comprising 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 acrylic acid-2-hydroxyethyl was added dropwise uniformly and gradually over 1 hour and 30 minutes to react. After 30 minutes of completion of the dropwise addition, 0.1 parts by weight of azobisisobutyronitrile was added, polymerization was carried out for an additional 5 hours, and ethyl acetate was added in the reactor to cool while diluting to obtain a solution of a random copolymer having a solid content of 40% by weight. As a result of measuring the weight average molecular weight of the obtained random copolymer by the GPC method, it was 370,000. "2690 Separations Module" manufactured by Water Corporation as a measuring instrument, "GPC KF-806L" manufactured by Showa Denko Co., Ltd. as a column, and ethyl acetate as a solvent, sample flow rate 1 ml/min, column temperature of 40°C measured.

The obtained random copolymer was dissolved in ethyl acetate so that the solid content was 35%, and with respect 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 of Tetrad C as a crosslinking agent were added. Furthermore, it fully stirred and obtained the base material solution. The obtained base material solution was coated on the release-treated surface of a 50 µm polyethylene terephthalate (PET) film subjected to a release treatment on one side, and dried at 90° C. for 7 minutes to obtain a non-foamed base material comprising a random copolymer. The thickness of the non-foam base material was adjusted to be 100 µm when the non-foam base material was heated at 130°C for 1 minute.

(2) Preparation of adhesive tape

An adhesive tape was obtained in the same manner as in Example 1 except that the non-foamed base material comprising the obtained random copolymer was used. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Example 39)

Except having made the composition of the foam base material like Table 2, it carried out similarly to Example 38, and obtained the adhesive tape. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Example 40)

An unfoamed base material made 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 shown in Table 2. Next, except having made the thickness of an adhesive layer like Table 2, it carried out similarly to Example 25, and obtained the adhesive tape. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Comparative Example 1)

Manufacture of an adhesive tape WHEREIN: It carried out similarly to Example 1, and obtained the adhesive tape, without adding a foaming agent, without heating for 130 degreeC 1 minute, except not having set it as a foam base material. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Comparative Example 2)

(1) Preparation of foam substrate

Volara H03001 (polyethylene resin, Sekisui Chemical Industry Co., Ltd. make, thickness 100 micrometers) was used as a foam base material.

(2) Preparation of adhesive tape

Except having used the obtained base material, it carried out similarly to Example 1, and obtained the adhesive tape. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Comparative Example 3)

(1) Preparation of foam substrate

Volara H0250012 (polyethylene resin, Sekisui Chemical Industry Co., Ltd. make, thickness 120 micrometers) was used as a foam base material.

(2) Preparation of adhesive tape

Except having used the obtained base material, it carried out similarly to Example 1, and obtained the adhesive tape. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Comparative Example 4)

(1) Preparation of substrate

Prepare a 30% solution of Septon 2063 (hydrocarbon-based resin, manufactured by Kuraray) in toluene, and use 0.5 parts by weight of Expancel 461-40 (manufactured by Nippon Fillite) as a foaming agent based on 100 parts by weight of solid content, without using a crosslinking agent. Except not having it, it carried out similarly to Example 1, and obtained the non-foam base material.

(2) Preparation of adhesive tape

Except having used the obtained non-foam base material, it carried out similarly to Example 1, and obtained the adhesive tape. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

(Comparative Example 5)

(1) Preparation of unfoamed substrate

Instead of the acrylic copolymer A, the acrylic random copolymer solution obtained in the preparation of the pressure-sensitive adhesive solution in Example 1 was used, and 1 part by weight of the crosslinking agent and 0.5 parts by weight of the foaming agent based on 100 parts by weight of the solid content of the acrylic random copolymer solution. Except having used, it carried out similarly to Example 1, and obtained the non-foaming base material. In addition, the following things were used for a crosslinking agent and a foaming agent.

Crosslinking agent: L-45E, manufactured by Tosoh Corporation

Foaming agent: Expancel 461-40, manufactured by Nippon Fillite

(2) Preparation of adhesive tape

Except having used the obtained non-foam base material, it carried out similarly to Example 1, and obtained the adhesive tape. About the obtained adhesive tape, each measurement was performed similarly to Example 1.

<Evaluation>

The following evaluation was performed about the adhesive tape obtained by the Example and the comparative example. The results are shown in Tables 1-3.

(Evaluation of impact resistance)

The obtained adhesive tape was punched out in a lo-shape with an outer shape of 45 mm x 60 mm and a width of 1 mm. The single side|surface of the punched-out adhesive tape was affixed on the center of the stainless steel plate of 80 mm x 115 mm and thickness 2 mm which has a 40 mm x 40 mm hole in the center part. Next, a laminated body for a test was obtained by affixing a tempered glass plate of 50 mm x 70 mm and a thickness of 4 mm to the other side of the adhesive tape, crimping with a weight of 5 kg for 10 seconds, and allowing it to stand at 23° C. for 24 hours. The obtained laminate was fixed to a stainless steel frame body (inner diameter: 60 mm x 90 mm) so that a tempered glass plate became the lower surface. Thereafter, a 150 g iron ball was dropped toward the center of the tempered glass plate. The height at which the iron ball is dropped was increased, and the height of the iron ball when the tempered glass plate was peeled off from the stainless plate was measured. When the tempered glass plate was peeled from the stainless steel plate, the height of the iron ball was 60 cm or more as "◎", when the height of the iron ball was 40 cm or more and less than 60 cm, "○", when the height was 20 cm or more and less than 40 cm, "△", The case where it was less than 20 cm was made into "x", and impact resistance was evaluated.

(Evaluation of holding power)

The schematic diagram explaining the holding force test of an adhesive tape in FIG. 1 is shown. First, one surface (surface) of the test piece 1 having a size of 25 mm x 25 mm of the adhesive tape is bonded to the SUS plate 2, and the other surface (rear surface) of the test piece 1 is 2 kg of rubber from the side. The rollers were reciprocated at a speed of 300 mm/min. Next, after bonding the aluminum plate 3 to the back surface of the test piece 1 and pressurizing and crimping|bonding for 10 second with a 0.5 kg weight from the aluminum plate 3 side, it is left to stand in the environment of 23 degreeC and 50% of relative humidity for 24 hours. Thus, a sample for the holding force test was prepared. A 0.5 kg or 1.0 kg weight 4 is attached to this holding force test sample at 100 ° C. so that a load is applied to one end of the aluminum plate 3 in the horizontal direction with respect to the test piece 1 and the aluminum plate 3, , the weight shift length after 1 hour was measured. Moreover, the shift|offset|difference length 2 hours after attaching the 1.0 kg weight 4 was also measured. Regarding the obtained measurement results, "double-circle" indicates the case where the deviation length is 0 (no deviation), "Δ" when the deviation length is greater than 0 and less than 1 mm, and the deviation length is 1 mm or more or the adhesive tape is peeled off. The case where it has fallen was made into "x", and the holding force was evaluated.

(Evaluation of tumble characteristics)

Two adhesive tapes cut out to 1 mm x 70 mm were prepared. Next, the adhesive tape was affixed on each short side of the polycarbonate board of 72 mm long, 135 mm wide, and thickness 1mm. Then, the surface to which the adhesive tape of the polycarbonate plate is affixed and the polycarbonate plate having a length of 77 mm, a width of 150 mm, and a thickness of 4 mm are overlapped so that the short sides of the two polycarbonate plates are opposed to each other, and 0.7 MPa, 15 The two polycarbonate boards were adhere|attached by super pressurization. Then, the test sample was obtained by leaving still for 24 hours at 23 degreeC. The obtained test sample was placed in a TD-1000A drum-type rotary drop tester (manufactured by Shin-Ei Electronics) and rotated at a speed of 12 revolutions/minute while maintaining a room temperature environment under 23° C., thereby rotating the measurement sample from a height of 1 m. repeatedly dropped. When the polycarbonate plate was peeled off, the case where the number of drops was more than 1500 was evaluated as "double-circle", the case where it was more than 1000 times and it was 1500 or less was "circle", and the case where it was 1000 times or less was "x", and tumble property was evaluated.

Industrial Applicability

ADVANTAGE OF THE INVENTION According to this invention, while having the outstanding flexibility and impact resistance, the adhesive tape excellent also in heat resistance can be provided.

1: Test piece of 25 mm x 25 mm in size of adhesive tape
2: SUS plate
3: aluminum plate
4: weight (0.5 kg or 1.0 kg)

Claims (13)

An adhesive tape having an adhesive layer on both sides of a foam substrate, the adhesive tape comprising:
The foam substrate contains a block copolymer having at least one hard block and one soft block, and the soft block is composed of a (meth)acrylic monomer. The method of claim 1,
The hard block has a structure derived from a monomer having a crosslinkable functional group, the adhesive tape. 3. The method according to claim 1 or 2,
The monomer having a crosslinkable functional group is at least one selected from the group consisting of a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an epoxy group-containing monomer, an amide group-containing monomer, a double bond-containing monomer, and a triple bond-containing monomer. 4. The method according to any one of claims 1 to 3,
The said hard block has a structure derived from a vinyl aromatic compound monomer, The adhesive tape. 5. The method according to any one of claims 1 to 4,
The said hard block has a structure derived from a vinyl aromatic compound monomer, and the structure derived from the monomer which has a crosslinkable functional group, The adhesive tape. 6. The method according to any one of claims 1 to 5,
The said block copolymer contains 1 weight% or more and 40 weight% or less of the said hard block, The adhesive tape. An adhesive tape having an adhesive layer on both sides of a foam substrate, the adhesive tape comprising:
The foam substrate contains a copolymer,
The copolymer has a structure derived from a vinyl aromatic compound monomer, a structure derived from a monomer having a crosslinkable functional group, and a structure derived from a (meth)acrylic monomer, an adhesive tape. 8. The method of claim 7,
The adhesive tape whose content of the structure derived from the said (meth)acrylic-type monomer in the said copolymer is 30 weight% or more and 99 weight% or less. 9. The method according to any one of claims 1 to 8,
The foam substrate has a gel fraction of 90% or less, an adhesive tape. 10. The method according to any one of claims 1 to 9,
The said foam base material is an adhesive tape whose considered density is 0.3 g/cm<3> or more and 0.75 g/cm<3> or less. 11. The method according to any one of claims 1 to 10,
The adhesive tape which has a resin layer on at least one surface of the said foam base material. 12. The method according to any one of claims 1 to 11,
The average cell diameter of the cells of the said foam base material is 80 micrometers or less, The adhesive tape. 13. The method according to any one of claims 1 to 12,
An adhesive tape used for fixing electronic components.

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