阅读说明：本技术 粘合带 (Adhesive tape ) 是由 渡边大亮 杉浦隆峰 于 2019-02-26 设计创作，主要内容包括：本发明要解决的课题在于,提供一种粘合带,其对被粘物特别是硬质的被粘物的追随性和粘接性优异,且剥离粘合带时不需要通过加热、有机溶剂等来使粘合带脆化,另外,具有粘合剂不会残留于被粘物、不仅在粘合带的水平方向上、即使成角度地拉伸也能够容易地剥离的优异的再剥离性。本发明涉及一种粘合带,其是具备含有填料的粘合层的粘合带,厚度大于150μm且小于1500μm,断裂伸长率为600～3000％,断裂应力为2.5～80.0MPa。(An object of the present invention is to provide a pressure-sensitive adhesive tape which has excellent followability and adhesiveness to an adherend, particularly a hard adherend, does not require embrittlement by heating, an organic solvent, or the like when the pressure-sensitive adhesive tape is peeled, and has excellent removability in which the pressure-sensitive adhesive tape can be easily peeled not only in a horizontal direction but also even when the pressure-sensitive adhesive tape is stretched at an angle without remaining on the adherend. The present invention relates to an adhesive tape having an adhesive layer containing a filler, the adhesive tape having a thickness of more than 150 μm and less than 1500 μm, an elongation at break of 600 to 3000%, and a stress at break of 2.5 to 80.0 MPa.)

1. An adhesive tape having an adhesive layer containing a filler, the adhesive tape having a thickness of more than 150 μm and less than 1500 μm, an elongation at break of 600 to 3000%, and a stress at break of 2.5 to 80.0 MPa.

2. The adhesive tape according to claim 1 or 2, wherein the adhesive tape has a stress at 25% elongation of 0.05MPa to 10 MPa.

3. Adhesive tape according to claim 1 or 2, wherein the adhesive tape has a storage elastic modulus E' at 23 ℃ of 1.0 × 10⁴Pa～1.0×10⁸Pa。

4. The adhesive tape according to any one of claims 1 to 3, wherein the adhesive tape has a 180 ° peel adhesion of 5N/20mm or more.

5. The adhesive tape according to any one of claims 1 to 4, further comprising a substrate.

Technical Field

The present invention relates to an adhesive tape.

Background

Adhesive tapes are widely used for fixing components constituting electronic devices. Specifically, the adhesive tape is used for fixing metal plates constituting relatively large electronic devices such as thin televisions, home electric appliances, OA devices, and the like, and fixing an exterior member and a housing; and fixing rigid members such as exterior members and batteries to relatively small electronic devices such as portable electronic terminals, cameras, and personal computers. These rigid members may have irregularities or strains, and the pressure-sensitive adhesive tape is required to have a following property of exhibiting a strong adhesive force while following the surface shape.

In addition, in the field of OA equipment such as thin televisions, home electric appliances, printers, and copiers, reusable components used for products are often disassembled and reused after use for the purpose of resource saving from the viewpoint of environmental compatibility. In this case, when the pressure-sensitive adhesive tape is used, the pressure-sensitive adhesive tape attached to the member needs to be peeled off, but there is a problem that the pressure-sensitive adhesive remains on the adherend at the time of peeling, the pressure-sensitive adhesive tape is broken, or the double-sided pressure-sensitive adhesive tape is damaged between the nonwoven fabric layers.

In addition, when hard materials such as metal and plastic are firmly bonded to each other using a conventional pressure-sensitive adhesive tape, it is necessary to peel off the pressure-sensitive adhesive tape by heating to soften the pressure-sensitive adhesive component, and in this case, the metal and plastic of the adherend to be reused have an influence such as deterioration due to heating. In addition, similarly, the pressure-sensitive adhesive tape may be peeled off by embrittling it using an organic solvent or the like, but also in the case of heating, the problem of deterioration of the adherend occurs.

In order to solve the above problems, a pressure-sensitive adhesive sheet has been proposed which is a transparent pressure-sensitive adhesive sheet tape-like sheet comprising 3 layers each of which is composed of a transparent adhesive based on a hydrogenated vinyl aromatic block copolymer and a tackifier resin (patent document 1). However, when 3 layers of a hydrogenated vinyl aromatic block copolymer and a tackifier are laminated as base layers, there is a problem that sufficient initial adhesion performance cannot be obtained, and when, for example, hard adherends having large strains are adhered to each other, the adhesive strength is lowered.

In addition, there is a method of utilizing a generally used pressure-sensitive adhesive tape having a strong adhesive force, but sufficient removability to be a problem cannot be secured.

Disclosure of Invention

Problems to be solved by the invention

An object of the present invention is to provide a pressure-sensitive adhesive tape which has excellent adhesiveness to an adherend, particularly a hard adherend, does not require embrittlement by heating, an organic solvent, or the like when the pressure-sensitive adhesive tape is peeled, and has excellent removability in which the pressure-sensitive adhesive tape can be easily peeled not only in a horizontal direction but also even when the pressure-sensitive adhesive tape is stretched at an angle without remaining on the adherend.

Means for solving the problems

The present inventors have conducted intensive studies so as to complete the present invention for solving the above problems.

The invention provides an adhesive tape, which is an adhesive tape provided with an adhesive layer containing fillers, and has a thickness of more than 150 [ mu ] m and less than 1500 [ mu ] m, an elongation at break of 600-3000%, and a stress at break of 2.5-80.0 MPa.

Effects of the invention

The pressure-sensitive adhesive tape of the present invention is excellent in adhesiveness even when hard adherends such as metal and plastic are bonded to each other, can be firmly adhered, does not require heating or an organic solvent to embrittle the pressure-sensitive adhesive tape when peeling the two, is free from residues such as a pressure-sensitive adhesive on the adherends, can be easily peeled off not only in a horizontal direction but also by being stretched at an angle, and can reuse the adherends.

Detailed Description

The structure of the pressure-sensitive adhesive tape of the present invention will be described in further detail below.

< adhesive tape >

The adhesive tape of the present invention has a thickness of more than 150 μm and less than 1500 μm, an elongation at break of 600 to 3000%, and a stress at break of 2.5 to 80.0 MPa.

The thickness of the pressure-sensitive adhesive tape is preferably more than 150. mu.m, more preferably 170 μm or more, still more preferably 200 μm or more, and particularly preferably 250 μm or more. The thickness of the adhesive tape is preferably less than 1500 μm, more preferably 1400 μm or less, still more preferably 1300 μm or less, and particularly preferably 1200 μm or less. When the thickness of the pressure-sensitive adhesive tape is in the above range, the pressure-sensitive adhesive tape can easily follow strain of an adherend, and excellent adhesive strength can be obtained, and the stress required when the pressure-sensitive adhesive tape is stretched in the horizontal direction and peeled off again does not become excessively large, which is preferable. The pressure-sensitive adhesive tape of the present invention is also conceivable in a case where the adherend is a hard large-area adherend such as metal or plastic. Generally, the larger the area of an adherend, the more difficult it is to form the adherend with reduced strain. By following such a strain of the adherend with the pressure-sensitive adhesive tape, a precise mechanism such as an electronic device can be completed more accurately.

The adhesive tape preferably has an elongation at break of 600 to 3000%, more preferably 650 to 2800%, still more preferably 700 to 2700%, and still more preferably 750 to 2600%. The pressure-sensitive adhesive tape of the present invention is thick and maintains a strong adhesive strength when the thickness is more than 150 and less than 1500 μm as described above. When the strongly adhesive pressure-sensitive adhesive tape of the present invention is stretched and peeled off, the pressure-sensitive adhesive tape can be peeled off with an appropriate tensile stress even when the pressure-sensitive adhesive tape is strongly adhered to an adherend in the elongation at break range, and the pressure-sensitive adhesive tape can be easily peeled off without being excessively stretched in the peeling step.

The pressure-sensitive adhesive tape preferably has a breaking stress of 2.5 to 80.0MPa, more preferably 3.0 to 60.0MPa, still more preferably 3.5 to 30.0MPa, and still more preferably 4.0 to 20.0 MPa. When the breaking stress of the adhesive tape is in the above range, the adhesive tape is not broken when the adhesive tape is pulled and peeled off, and the adhesive tape is easily appropriately elongated, so that the peeling-off operation by peeling off is facilitated. In addition, the force required to stretch and deform the adhesive tape also depends on the thickness of the adhesive tape. For example, when an adhesive tape having a large thickness and a high breaking stress is stretched and peeled again, the adhesive tape cannot be sufficiently stretched and cannot be peeled again.

The pressure-sensitive adhesive tape preferably has a stress at 25% elongation of 0.05 to 10.0MPa, more preferably 0.1 to 5.0MPa, still more preferably 0.15 to 3.0MPa, and still more preferably 0.2 to 2.0 MPa. When the stress at 25% elongation of the pressure-sensitive adhesive tape is in the above range, the pressure-sensitive adhesive tape can have an appropriate adhesive strength and can be peeled off relatively easily even in the re-peeling step. If the amount of the binder is less than the above range, the binder may peel off when the hard adherends are fixed to each other and a load is applied in the shearing direction of the binder. If the amount is more than the above range, the force required to extend the adhesive tape in the step of peeling the adhesive tape becomes too large.

The pressure-sensitive adhesive tape preferably has a stress at 50% elongation of 0.05 to 10.5MPa, more preferably 0.1 to 5.5MPa, still more preferably 0.15 to 3.5MPa, and still more preferably 0.2 to 2.5 MPa. When the stress at 50% elongation of the pressure-sensitive adhesive tape is in the above range, the pressure-sensitive adhesive tape can have an appropriate adhesive strength and can be peeled off relatively easily even in the re-peeling step. If the amount of the binder is less than the above range, the binder may peel off when the hard adherends are fixed to each other and a load is applied in the shearing direction of the binder. If the amount is more than the above range, the force required to extend the adhesive tape in the step of peeling the adhesive tape becomes too large.

The 50% elongation stress of the adhesive tape is preferably 100 to 160%, more preferably 103 to 150%, even more preferably 105 to 140%, and even more preferably 110 to 130% of the 25% elongation stress.

When the stress at 50% elongation of the adhesive tape is in the above range with respect to the stress at 25% elongation, the stress required for peeling in the peeling step at the time of peeling the adhesive tape again can be stabilized.

The storage elastic modulus E' (23 ℃) of the adhesive tape at 23 ℃ is preferably 1.0 × 10⁴～1.0×10⁸Pa, more preferably 5.0 × 10⁴～5.0×10⁷Pa, further preferablyIs selected to be 1.0 × 10⁵～1.0×10⁷Pa, more preferably 3.0 × 10⁵～8.0×10⁶Pa. When the breaking stress of the pressure-sensitive adhesive tape is in the above range, the pressure-sensitive adhesive tape can easily follow the strain of the adherend, can easily obtain excellent adhesive strength, and can secure dimensional stability of the pressure-sensitive adhesive tape, and therefore can obtain suitable adhesion workability. As described above, the pressure-sensitive adhesive tape of the present invention is also conceivable in a case where the adherend is a hard and large-area adherend such as metal or plastic. Generally, the larger the area of an adherend, the more difficult it is to form the adherend with reduced strain. When the pressure-sensitive adhesive tape has the storage elastic modulus range, the pressure-sensitive adhesive tape can follow the strain of the adherend as described above, and an appropriate adhesive strength can be obtained.

The 180 DEG peel adhesion of the pressure-sensitive adhesive tape is preferably 5N/20mm or more, more preferably 7N/20mm or more, still more preferably 9N/20mm or more, and still more preferably 12N/20mm or more. When the 180 ° peel adhesion of the pressure-sensitive adhesive tape is in the above range, excellent adhesion is easily obtained even when the adherends are rigid bodies. In the stretchable pressure-sensitive adhesive tape of the present invention, a 180 ° peel adhesion force lower than the above range suggests that the interfacial adhesion strength to an adherend is low. Therefore, when the adhesive is used for bonding rigid bodies to each other, there is a risk that sufficient adhesive strength cannot be obtained.

< adhesion layer >

The adhesive tape of the present invention includes an adhesive layer containing a filler. As the adhesive layer, a conventionally known adhesive can be used.

(Filler)

The adhesive layer of the adhesive tape of the present invention contains a filler.

As the filler constituting the adhesive tape of the present invention, 1 or more kinds of fillers selected from various inorganic fillers such as metals, metal hydroxides, metal oxides, silicates, carbon, silica and organic beads can be used.

Examples of the metal include aluminum, magnesium, zirconium, calcium, barium, tin, nickel, titanium, copper, silver, and gold.

Examples of the metal hydroxide include aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, calcium hydroxide, and barium hydroxide.

Examples of the metal oxide include silicon oxide, magnesium oxide, zinc oxide, titanium oxide, zirconium oxide, iron oxide, aluminum oxide, and calcium oxide.

Examples of the silicate include talc and mica.

The type of the filler may be selected according to the performance required for the adhesive tape, and for example, aluminum hydroxide or magnesium hydroxide is preferably used in order to impart flame retardancy. In particular, aluminum hydroxide is preferred because it causes a thermal decomposition reaction from about 250 ℃ and exerts a flame retardant effect before the adhesive tape is significantly melted.

The shape of the filler may be either regular or irregular, but it is preferable to use a filler having a non-plate or non-scaly shape. The non-plate-like or non-scaly shape is a shape having an aspect ratio of about 1 to 10. Among them, the aspect ratio is preferably 1 to 10, more preferably 1 to 9, and further preferably 1 to 8.

Further, the filler is preferably used in an average particle size of 0.01 to 70 μm, more preferably 0.05 to 50 μm, still more preferably 0.1 to 30 μm, and yet more preferably 0.5 to 15 μm. By setting the above range, it is possible to achieve both of more excellent pressure-sensitive adhesive performance and excellent removability. The average particle size is a value measured using a Microtrac particle size distribution measuring apparatus 9320HRA (manufactured by Nikkiso K.K.).

The filler is used in a range of preferably 1 to 80 vol%, more preferably 10 to 75 vol%, still more preferably 15 to 70 vol%, and still more preferably 20 to 60 vol%, based on the total volume of the components constituting the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape, in order to obtain still more excellent removability. By setting the above range, it is possible to achieve both of more excellent pressure-sensitive adhesive performance and excellent removability.

The thickness of the adhesive layer may vary depending on the structure of the adhesive tape of the present invention. When the adhesive tape of the present invention is composed of only the adhesive layer, it is preferably larger than 150 μm, more preferably 170 μm or more, further preferably 200 μm or more, and particularly preferably 250 μm or more. The thickness of the adhesive tape is preferably less than 1500 μm, more preferably 1400 μm or less, still more preferably 1300 μm or less, and particularly preferably 1200 μm or less. When the base material is provided in the pressure-sensitive adhesive tape of the present invention, the thickness of the base material layer is preferably 1/2 to 1/500, more preferably 1/3 to 1/300, still more preferably 1/5 to 1/200, and still more preferably 1/5 to 1/50. When the thickness ratio of the adhesive layer to the base layer of the adhesive tape is in the above range, excellent adhesiveness and removability of the adhesive tape can be obtained. Since the cohesive force of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention is lower than that of the substrate, when the pressure-sensitive adhesive layer is thicker than the above range, only the pressure-sensitive adhesive layer may remain on the adherend in the step of peeling the pressure-sensitive adhesive tape again. When the pressure-sensitive adhesive layer is thinner than the above range, the pressure-sensitive adhesive layer may not follow the uneven surface of the adherend, and the adhesive strength may be significantly reduced.

The breaking stress of the adhesive layer is preferably 0.5 to 25.0MPa, more preferably 0.8 to 20.0MPa, still more preferably 1.0 to 17.0MPa, and still more preferably 1.2 to 15.0 MPa. When the breaking stress of the pressure-sensitive adhesive layer is in the above range, excellent pressure-sensitive adhesive properties can be exhibited, and the pressure-sensitive adhesive tape of the present invention is preferably used because the pressure-sensitive adhesive component is less likely to remain on an adherend when the pressure-sensitive adhesive tape is horizontally stretched and peeled.

Examples of the adhesive used for the adhesive layer include acrylic adhesives; a urethane-based adhesive; rubber-based adhesives such as synthetic rubber-based adhesives and natural rubber-based adhesives; silicone-based adhesives, and the like.

(acrylic adhesive)

As the acrylic pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive containing an acrylic polymer and, if necessary, additives such as a tackifier resin and a crosslinking agent can be used.

The acrylic polymer can be produced, for example, by polymerizing a monomer mixture containing a (meth) acrylic monomer.

Examples of the (meth) acrylic monomer include alkyl (meth) acrylates having an alkyl group having 1 to 12 carbon atoms, such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, which may be used alone or in combination of 2 or more.

The alkyl (meth) acrylate having an alkyl group with 1 to 12 carbon atoms is preferably an alkyl (meth) acrylate having an alkyl group with 4 to 12 carbon atoms, more preferably an alkyl (meth) acrylate having an alkyl group with 4 to 8 carbon atoms, and particularly preferably n-butyl acrylate in order to ensure excellent adhesion to an adherend.

The alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms is preferably used in a range of 80 to 98.5% by mass, more preferably 90 to 98.5% by mass, based on the total amount of monomers used for producing the acrylic polymer.

As the monomer that can be used for producing the acrylic polymer, a highly polar vinyl monomer may be used, if necessary, in addition to the above-mentioned monomers.

Examples of the highly polar vinyl monomer include (meth) acrylic monomers such as a (meth) acrylic monomer having a hydroxyl group, a (meth) acrylic monomer having a carboxyl group, and a (meth) acrylic monomer having an amide group, which are used singly or in combination of 2 or more.

Examples of the vinyl monomer having a hydroxyl group include (meth) acrylic monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate.

As the vinyl monomer having a carboxyl group, a (meth) acrylic monomer such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth) acrylic acid dimer, crotonic acid, ethylene oxide-modified succinic acid acrylate, or the like can be used, and among them, acrylic acid is preferably used.

As the vinyl group having an amide group, a (meth) acrylic monomer such as N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, N-dimethylacrylamide, or the like can be used.

As the high-polarity vinyl monomer, in addition to the above-mentioned monomers, a sulfonic acid group-containing monomer such as vinyl acetate, ethylene oxide-modified succinic acid acrylate, 2-acrylamido-2-methylpropanesulfonic acid, or the like can be used.

The highly polar vinyl monomer is preferably used in a range of 1.5 to 20 mass%, more preferably 1.5 to 10 mass%, and even more preferably 2 to 8 mass%, based on the total amount of monomers used for producing the acrylic polymer, since a pressure-sensitive adhesive layer having a balanced cohesive force, holding force, and adhesive property can be formed.

Among the highly polar vinyl monomers, the vinyl monomer having a hydroxyl group is preferably used when a binder containing an isocyanate-based crosslinking agent is used as the binder. Specifically, as the vinyl monomer having a hydroxyl group, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate are preferably used.

The hydroxyl group-containing vinyl monomer is used preferably in a range of 0.01 to 1.0% by mass, more preferably in a range of 0.03 to 0.3% by mass, based on the total amount of monomers used for producing the acrylic polymer.

The acrylic polymer can be produced by polymerizing the monomer by a known polymerization method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method, and is preferably produced by a solution polymerization method or a bulk polymerization method.

In the polymerization, a peroxide-based thermal polymerization initiator such as benzoyl peroxide or lauroyl peroxide, an azo-based thermal polymerization initiator such as azobisisobutyronitrile, an acetophenone-based photopolymerization initiator, a benzoin ether-based photopolymerization initiator, a benzoin ketal-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, or the like can be used as necessary.

The weight average molecular weight of the acrylic polymer obtained by the above method is preferably 30 to 300 ten thousand, more preferably 50 to 250 ten thousand, in terms of standard polystyrene measured by Gel Permeation Chromatography (GPC).

The molecular weight was measured by GPC as a standard polystyrene value measured by a GPC apparatus (HLC-8329GPC) available from Tosoh corporation under the following conditions.

Sample concentration: 0.5% by mass (tetrahydrofuran solution)

Sample injection amount: 100 μ L

Eluent: THF (tetrahydrofuran)

Flow rate: 1.0 mL/min

Measuring temperature: 40 deg.C

Main column: TSKgel GMHHR-H (20)2 root

Protection of the column: TSKgel HXL-H

A detector: differential refractometer

Molecular weight of standard polystyrene: 1 to 2000 thousands (made by Tosoh corporation)

As the acrylic pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive containing a tackifier resin is preferably used in order to improve adhesion to an adherend and surface adhesive strength.

As the tackifier resin, a rosin-based tackifier resin, a polymerized rosin ester-based tackifier resin, a rosin phenol-based tackifier resin, a stabilized rosin ester-based tackifier resin, a disproportionated rosin ester-based tackifier resin, a hydrogenated rosin ester-based tackifier resin, a terpene phenol-based tackifier resin, a petroleum resin-based tackifier resin, a (a) acrylic ester-based tackifier resin, and the like can be used.

Among them, as the above-mentioned tackifier resin, a disproportionated rosin ester tackifier resin, a polymerized rosin ester tackifier resin, a rosin phenol tackifier resin, a hydrogenated rosin ester tackifier resin, a (meth) acrylic ester tackifier resin, and a terpene phenol tackifier resin are preferably used singly or in combination of 2 or more.

As the above-mentioned tackifier resin, a tackifier resin having a softening point of 30 to 180 ℃ is preferably used, and a tackifier resin having a softening point of 70 to 140 ℃ is more preferably used in forming an adhesive layer having high adhesive performance. When a (meth) acrylate-based tackifier resin is used, it is preferable to use a (meth) acrylate-based tackifier resin having a glass transition temperature of 30 to 200 ℃, and more preferably a (meth) acrylate-based tackifier resin having a glass transition temperature of 50 to 160 ℃.

The tackifier resin is preferably used in a range of 5 to 65 parts by mass and more preferably in a range of 8 to 55 parts by mass with respect to 100 parts by mass of the acrylic polymer, since adhesion to an adherend is easily secured.

As the acrylic pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive containing a crosslinking agent is preferably used in order to further increase the cohesive force of the pressure-sensitive adhesive layer. As the crosslinking agent, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a metal chelate-based crosslinking agent, an aziridine-based crosslinking agent, or the like can be used. Among them, as the crosslinking agent, a crosslinking agent of a type which is mixed after the production of the acrylic polymer and advances the crosslinking reaction is preferable, and an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent which are highly reactive with the acrylic polymer are preferably used.

Examples of the isocyanate-based crosslinking agent include toluene diisocyanate, naphthalene-1, 5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, trimethylolpropane-modified toluene diisocyanate, and the like. Particularly preferred are 3-functional polyisocyanate-based compounds. Examples of the 3-functional isocyanate compound include tolylene diisocyanate, trimethylolpropane adducts thereof, and triphenylmethane isocyanate.

As an index of the degree of crosslinking, a value for measuring the gel fraction of insoluble components after the adhesive layer was immersed in toluene for 24 hours can be used. The gel fraction of the pressure-sensitive adhesive layer is preferably 10 to 70% by mass, more preferably 25 to 65% by mass, and the gel fraction is more preferably 35 to 60% by mass in order to obtain a pressure-sensitive adhesive layer having good cohesiveness and adhesiveness.

The gel fraction is a value measured by the following method. The adhesive composition was applied to a release sheet so that the thickness after drying was 50 μm, dried at 100 ℃ for 3 minutes, aged at 40 ℃ for 2 days, and the aged product was cut out to a 50mm square to prepare a sample. Next, the mass of the sample before toluene immersion was measured in advance (G1), and the toluene-insoluble matter of the sample after immersion in a toluene solution at 23 ℃ for 24 hours was separated by filtration through a 300-mesh wire gauze, and after drying at 110 ℃ for 1 hour, the mass of the residue was measured (G2), and the gel fraction was determined according to the following formula. The weight (G3) of the conductive fine particles in the sample was calculated from the mass (G1) of the sample and the composition of the binder.

Gel percentage (mass%) (G2-G3)/(G1-G3) × 100

The adhesive layer of the adhesive tape of the present invention contains the above-mentioned filler, but if necessary, an adhesive layer containing the following as an additive to other adhesives may be used within a range not impairing the properties: additives such as other polymer components, crosslinking agents, anti-aging agents, ultraviolet absorbers, fillers, polymerization inhibitors, surface modifiers, antistatic agents, antifoaming agents, viscosity modifiers, light-resistant stabilizers, weather-resistant stabilizers, heat-resistant stabilizers, antioxidants, leveling agents, organic pigments, inorganic pigments, pigment dispersants, plasticizers, softeners, flame retardants, metal deactivators, and the like; inorganic fillers such as silica, alumina, titania, zirconia, and antimony pentoxide.

(rubber-based adhesive)

As the rubber-based adhesive, a rubber material generally used as an adhesive can be used, but as a particularly preferable embodiment, a block copolymer of a polyaromatic vinyl compound and a conjugated diene compound, in particular, a styrene-based resin such as a styrene-isoprene-styrene copolymer, a styrene-butadiene-styrene copolymer, a styrene-ethylene-butylene copolymer, or a styrene-ethylene-propylene copolymer can be suitably used.

As the styrene-based resin used in the adhesive of the adhesive tape of the present invention, a styrene-isoprene copolymer or/and a styrene-isoprene-styrene copolymer or/and a mixture of a styrene-isoprene copolymer and a styrene-isoprene-styrene copolymer can be used. The styrene resin composed of the above components imparts excellent adhesive properties and holding power to the pressure-sensitive adhesive tape of the present invention.

The styrene resin is preferably a styrene resin having a structural unit represented by the following chemical formula (1) in a range of 10 to 80% by mass, more preferably a styrene resin having a structural unit represented by the following chemical formula (1) in a range of 12 to 60% by mass, even more preferably a styrene resin having a structural unit represented by the following chemical formula (1) in a range of 15 to 40% by mass, and even more preferably a styrene resin having a structural unit represented by the following chemical formula (1) in a range of 17 to 35% by mass, based on the total mass of the styrene-isoprene copolymer and the styrene-isoprene-styrene copolymer. This can provide excellent adhesiveness and heat resistance.

[ chemical formula 1]

As the styrene-based resin, a styrene-based resin containing 2 or more copolymers having different structures can be used, and a styrene-based resin containing a styrene-isoprene copolymer and a styrene-isoprene-styrene copolymer in combination can be used.

The styrene-based resin is preferably a styrene-based resin containing the styrene-isoprene copolymer in a range of 0 to 80% by mass, more preferably a styrene-based resin containing the styrene-isoprene copolymer in a range of 0 to 77% by mass, even more preferably a styrene-based resin containing the styrene-isoprene copolymer in a range of 0 to 75% by mass, and even more preferably a styrene-based resin containing the styrene-isoprene copolymer in a range of 0 to 70% by mass, relative to the total mass of the styrene-isoprene copolymer and the styrene-isoprene-styrene copolymer. By setting the above range, the pressure-sensitive adhesive tape of the present invention can achieve both excellent adhesion performance and thermal durability.

The styrene-isoprene copolymer is preferably a styrene-isoprene copolymer having a weight average molecular weight in a range of 1 to 80 ten thousand, more preferably a styrene-isoprene copolymer having a weight average molecular weight in a range of 3 to 50 ten thousand, and even more preferably a styrene-isoprene copolymer having a weight average molecular weight in a range of 5 to 30 ten thousand, the weight average molecular weight being a weight average molecular weight measured by Gel Permeation Chromatography (GPC) in terms of standard polystyrene (gel permeation chromatography, SC-8020 manufactured by tokyo corporation, high molecular weight column tskgel gmhhr-H, solvent: tetrahydrofuran). The above range ensures both fluidity by heating and compatibility when diluted with a solvent, and therefore, the workability in the production process is good, and it is more preferable to obtain an adhesive tape having thermal durability.

As the styrene-based resin, for example, a styrene-based resin having a single structure such as a linear structure, a branched structure or a multi-branched structure can be used, and a styrene-based resin having a different structure can be used in combination. When a styrene resin having a rich linear structure is used for the adhesive layer, excellent adhesive performance is imparted to the adhesive tape of the present invention. On the other hand, a styrene-based resin having a branched structure or a multi-branched structure and having a styrene block disposed at a molecular end can have a quasi-crosslinked structure and can impart an excellent cohesive force, and thus can impart a high holding force. They are preferably used in combination according to the desired characteristics.

The method for producing the styrene-isoprene-styrene copolymer is not particularly limited, and conventionally known production methods can be applied, and the styrene-isoprene-styrene copolymer can be produced by the same method as described for the above-mentioned base material.

In addition, as the rubber-based adhesive, a tackifier resin can be used, and among them, a tackifier resin having a softening point of 80 ℃ or higher is preferably used. Thus, an adhesive and an adhesive tape having excellent initial adhesiveness and thermal durability can be obtained. The softening point is a value measured by the method (dry bulb method) defined in JISK 2207.

As the tackifier resin, for example, a tackifier resin which is solid at room temperature (23 ℃) is preferably used, and C can be used₅Petroleum resin, C₅System C₉Petroleum resins such as petroleum resins and alicyclic petroleum resins. The petroleum resin is easily compatible with the polyisoprene structure constituting the styrene resin, and as a result, the initial adhesion and thermal durability of the adhesive and the pressure-sensitive adhesive tape can be further improved.

As the above-mentioned C₅As the petroleum resin, an aliphatic petroleum resin can be used, and examples thereof include Escorez1202, 1304, 1401 (manufactured by Toyobo chemical Co., Ltd.), Wingtack 95 (manufactured by Goodyear fire and rubber company), Quintone K100, R100, F100 (manufactured by Nippon Rikusho Co., Ltd.), Piccotac 95, and Piccopale100 (manufactured by physicochemical Hercules).

As the above-mentioned C₅System C₉The above-mentioned resin C can be used as the petroleum resin₅Petroleum resin and C₉As the copolymer of a petroleum resin, for example, Escorez 2101 (manufactured by TONEX), Quintone G115 (manufactured by Nippon Ralskii), Hercotac1149 (manufactured by physiochemical Hercules) and the like can be used.

The alicyclic petroleum resin may beFor C above₉Examples of the hydrogenated petroleum resin include Escorez 5300 (manufactured by TONEX), Arkon P-100 (manufactured by Mitsuwa chemical industry), and Regalite R101 (manufactured by physicecech).

A tackifier resin having a softening point of 80 ℃ or higher, excluding the above-mentioned C₅Petroleum resin, C₅System C₉As the resin other than the petroleum resin and alicyclic petroleum resin, for example, a polymerized rosin resin and C₉Petroleum resin, terpene resin, rosin resin, terpene-phenol resin, styrene resin, coumarone-indene resin, xylene resin, phenol resin, and the like.

Wherein the above-mentioned C is used in combination as the tackifier resin having a softening point of 80 ℃ or higher₅The petroleum resin and the polymerized rosin resin are preferable in that they have both further excellent initial adhesion and thermal durability.

The tackifier resin having a softening point of 80 ℃ or higher is preferably used in a range of 3 to 100 mass%, more preferably in a range of 5 to 80 mass%, and even more preferably in a range of 5 to 80 mass%, based on the total amount of the styrene resin, in order to obtain an adhesive agent and an adhesive tape which are further excellent in adhesiveness and excellent in thermal durability.

In order to obtain the adhesiveness and initial adhesiveness in a constant temperature environment, a tackifier resin having a softening point of-5 ℃ or lower may be used in combination with the tackifier resin having a softening point of 80 ℃ or higher. The above-mentioned flow point is a value measured by a method based on the method defined in JISK 2269.

As the above-mentioned tackifier resin having a softening point of-5 ℃ or lower, a tackifier resin which is liquid at room temperature is preferably used. Such a tackifier resin that is liquid at room temperature is preferably selected from the known tackifier resins described above.

As the tackifier resin having a softening point of-5 ℃ or lower, for example, processing oil, polyester, liquid rubber such as polybutene, or the like can be used, and among them, polybutene is preferably used in order to exhibit further excellent initial adhesiveness.

The tackifier resin having a softening point of-5 ℃ or lower is preferably used in a range of 0 to 40% by mass, more preferably 0 to 30% by mass, based on the total amount of the tackifier resin.

The tackifier resin having a softening point of-5 ℃ or lower is preferably used in a range of 0 to 40% by mass based on the total amount of the styrene resin, and in a range of 0 to 30% by mass, the tackifier resin can improve initial adhesion to achieve good adhesion and sufficient thermal durability.

The mass ratio of the tackifier resin having a softening point of 80 ℃ or higher to the tackifier resin having a softening point of-5 ℃ or lower is preferably in the range of 5 to 50, and more preferably in the range of 10 to 30, in order to obtain an adhesive and an adhesive tape which are excellent in both initial adhesiveness and holding power.

The styrene resin and the tackifier resin are preferably used in combination in a mass ratio of [ styrene resin/tackifier resin ] of 0.5 to 10.0, and an initial adhesive strength of 0.6 to 9.0 can be improved and excellent thermal durability can be obtained. Further, it is preferable that the mass ratio [ styrene resin/tackifier resin ] is more than 1 in order to prevent the pressure-sensitive adhesive tape from peeling off (repulsion resistance) due to its repulsive force when it is adhered to, for example, a curved surface portion of an adherend.

The adhesive layer of the adhesive tape of the present invention contains the above-mentioned filler, but if necessary, an adhesive layer containing the following as an additive to other adhesives may be used within a range not impairing the properties: additives such as other polymer components, crosslinking agents, anti-aging agents, ultraviolet absorbers, fillers, polymerization inhibitors, surface modifiers, antistatic agents, antifoaming agents, viscosity modifiers, light-resistant stabilizers, weather-resistant stabilizers, heat-resistant stabilizers, antioxidants, leveling agents, organic pigments, inorganic pigments, pigment dispersants, plasticizers, softeners, flame retardants, metal deactivators, and the like; inorganic fillers such as silica, alumina, titania, zirconia, and antimony pentoxide.

As the above-mentioned antioxidant, antioxidants generally used for adhesives can be used, and examples thereof include the antioxidants described in the above-mentioned item for substrates.

As a method for producing the pressure-sensitive adhesive layer, there are a casting method by extrusion molding, a uniaxial stretching method, a sequential secondary stretching method, a simultaneous biaxial stretching method, a blow molding method, a tube molding method, a rolling method, a solution method, and the like. Among them, a casting method by extrusion molding or a manufacturing method by a solvent method may be suitably used, and the method may be selected according to the thickness control of the adhesive layer and the suitability for the lamination method with the substrate.

In the case of the solvent method, a method of directly applying the composition to a base material by a roll coater or the like, or a method of temporarily forming an adhesive layer on a release liner and then releasing the adhesive layer may be used.

Examples of the release liner include paper such as kraft paper, cellophane, and woodfree paper; resin films of polyethylene, polypropylene (OPP, CPP), polyethylene terephthalate, and the like; a laminate paper obtained by laminating the paper and a resin film, a product obtained by applying a peeling treatment such as a silicone resin to one surface or both surfaces of a product obtained by sealing the paper with clay, polyvinyl alcohol, or the like, and the like.

< substrate >

As a preferable embodiment of the pressure-sensitive adhesive tape of the present invention, a base material is provided in addition to a pressure-sensitive adhesive layer for bonding the pressure-sensitive adhesive tape to an adherend. The adhesive layer may be provided on one side or both sides of the substrate, and is preferably provided on both sides. When the base material is provided, the thickness is preferably 100 to 1490 μm, more preferably 120 to 1390 μm, still more preferably 150 to 1290 μm, and still more preferably 200 to 1190 μm. When the thickness of the substrate is in the above range, a high adhesive strength that allows the adhesive tape to easily follow strain of an adherend can be easily obtained, and the stress required when the adhesive tape is peeled off again while being stretched in the horizontal direction is not excessively large, which is preferable.

The substrate of the adhesive tape preferably has an elongation at break of 600 to 3000%, more preferably 650 to 2800%, still more preferably 700 to 2700%, and still more preferably 750 to 2600%. When the elongation at break of the base material is not less than the lower limit of the above range, even when the pressure-sensitive adhesive tape is firmly adhered to an adherend, the stress for stretching the pressure-sensitive adhesive tape in the horizontal direction when the pressure-sensitive adhesive tape is peeled off again does not become excessively large, and the pressure-sensitive adhesive tape can be easily peeled off without being excessively stretched in the peeling step. Further, it is preferable that the elongation at break of the base material is not more than the upper limit of the above range, because the stretching distance in the horizontal direction of the pressure-sensitive adhesive tape does not become excessively long when the pressure-sensitive adhesive tape is peeled again, and the operation in a small space becomes possible.

The breaking stress of the base material is preferably 2.5 to 80.0MPa, more preferably 3.0 to 60.0MPa, still more preferably 3.5 to 30.0MPa, and still more preferably 4.0 to 20.0 MPa. When the breaking stress of the base material is in the above range, the pressure-sensitive adhesive tape can be prevented from being broken when the pressure-sensitive adhesive tape is pulled and peeled, and the load for extending the pressure-sensitive adhesive tape does not become excessive, so that the peeling operation by peeling becomes easy. In addition, the force required to stretch and deform the adhesive tape also depends on the thickness of the adhesive tape. For example, when an adhesive tape having a large thickness and a high breaking stress is stretched and peeled again, the adhesive tape cannot be sufficiently stretched and cannot be peeled again.

The base material preferably has a stress at 25% elongation of 0.15 to 10.0MPa, more preferably 0.25 to 7.0MPa, still more preferably 0.35 to 5.0MPa, and yet more preferably 0.45 to 2.0 MPa. When the stress at 25% elongation of the pressure-sensitive adhesive tape is in the above range, the pressure-sensitive adhesive tape can have an appropriate adhesive strength and can be peeled off relatively easily even in the re-peeling step. If the amount of the binder is less than the above range, the binder may peel off when the hard adherends are fixed to each other and a load is applied in the shearing direction of the binder. If the amount is more than the above range, the force required to extend the adhesive tape in the step of peeling the adhesive tape becomes too large.

The base material preferably has a stress at 50% elongation of 0.15 to 10.0MPa, more preferably 0.25 to 7.0MPa, still more preferably 0.35 to 5.0MPa, and yet more preferably 0.50 to 2.0 MPa. When the stress at 50% elongation of the pressure-sensitive adhesive tape is in the above range, the pressure-sensitive adhesive tape can have an appropriate adhesive strength and can be peeled off relatively easily even in the re-peeling step. If the amount of the binder is less than the above range, the binder may peel off when the hard adherends are fixed to each other and a load is applied in the shearing direction of the binder. If the amount is more than the above range, the force required to extend the adhesive tape in the step of peeling the adhesive tape becomes too large.

The base material of the adhesive tape preferably has a stress at 50% elongation of 100 to 160%, more preferably 103 to 150%, still more preferably 105 to 140%, and still more preferably 110 to 130% of the stress at 25% elongation.

When the stress at 50% elongation of the adhesive tape is in the above range with respect to the stress at 25% elongation, the stress required for peeling in the re-peeling step at the time of re-peeling of the adhesive tape can be stabilized.

The storage elastic modulus E' (23 ℃) of the above base material at 23 ℃ is preferably 1.0 × 10⁴～1.0×10⁸Pa, more preferably 5.0 × 10⁴～5.0×10⁷Pa, more preferably 1.0 × 10⁵～1.0×10⁷Pa, more preferably 3.0 × 10⁵～8.0×10⁶Pa. When the breaking stress of the substrate is in the above range, the strain of the adherend can be easily followed, excellent adhesive strength can be obtained, and the dimensional stability of the pressure-sensitive adhesive tape can be ensured, so that suitable adhesion workability can be obtained. As described above, the pressure-sensitive adhesive tape of the present invention is also assumed to have a hard and large-area adherend such as metal or plastic. Generally, the larger the area of an adherend, the more difficult it is to mold the adherend with reduced strain, but if the pressure-sensitive adhesive tape has the storage elastic modulus range, the pressure-sensitive adhesive tape can follow the strain of the adherend as described above, and a suitable adhesive strength can be obtained.

The material constituting the base material of the pressure-sensitive adhesive tape of the present invention may be any material as long as it can exhibit the above-mentioned properties, and for example, a block copolymer of a polyaromatic vinyl compound and a conjugated diene compound, particularly a styrene-based resin such as a styrene-isoprene-styrene copolymer, a styrene-butadiene-styrene copolymer, a styrene-ethylenebutylene copolymer, a styrene-ethylenepropylene copolymer, or the like can be used. Further, polyurethane resins such as ester polyurethane and ether polyurethane; polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene, polycarbonate, polymethylpentene, polysulfone, polyetheretherketone, polyethersulfone, polyetherimide, polyimide film, fluororesin, nylon, acrylic resin, and the like. Styrene resins such as styrene isoprene styrene copolymers, styrene butadiene styrene copolymers, styrene ethylene butylene copolymers, and styrene ethylene propylene copolymers; polyurethane resins such as ester-based polyurethanes and ether-based polyurethanes can be suitably used because they can easily give suitable elongation at break and stress at break, and in particular, styrene-based resins such as styrene-isoprene-styrene copolymer, styrene-butadiene-styrene copolymer, styrene-ethylene-butylene copolymer and styrene-ethylene-propylene copolymer can be suitably used.

As described above, as the substrate of the pressure-sensitive adhesive tape of the present invention, a styrene resin film in which the main component of the resin component is a styrene resin is preferable, and the styrene resin film may include a resin film in which the styrene resin accounts for more than 50% of the resin component. Since a styrene resin is a resin exhibiting thermoplasticity, it is excellent in moldability such as extrusion molding and injection molding, and therefore, a base material for constituting the pressure-sensitive adhesive tape of the present invention can be easily molded. Among resins generally called thermoplastic resins, styrenic resins are particularly excellent in elongation at break and can be suitably used as a base material for the pressure-sensitive adhesive tape of the present invention.

The styrene resin is preferably contained in the resin component in a proportion of 50 to 100%, more preferably 60 to 100%, even more preferably 65 to 100%, and even more preferably 70 to 100%. When the amount is within this range, the styrene resin can have excellent elongation at break and stress at break. As the resin other than the styrene resin contained in the styrene resin film, various thermoplastic resins such as polyolefin and polycarbonate can be used, and one or more of them can be used.

As one embodiment for producing the pressure-sensitive adhesive tape of the present invention, the styrene-based resin used for the base material of the pressure-sensitive adhesive tape is a styrene-isoprene copolymer, or/and a styrene-isoprene-styrene copolymer, or/and a mixture of a styrene-isoprene copolymer and a styrene-isoprene-styrene copolymer. The styrene resin containing the above components can produce a pressure-sensitive adhesive tape having particularly preferable elongation at break and stress at break.

The styrene resin is preferably a styrene resin having a structural unit represented by the following chemical formula (2) in a range of 13 to 60 mass%, more preferably a styrene resin having a structural unit represented by the following chemical formula (2) in a range of 15 to 50 mass%, even more preferably a styrene resin having a structural unit represented by the following chemical formula (2) in a range of 16 to 45 mass%, and even more preferably a styrene resin having a structural unit represented by the following chemical formula (2) in a range of 17 to 35 mass%, based on the total mass of the styrene-isoprene copolymer and the styrene-isoprene-styrene copolymer. This makes it easy to obtain the elongation at break and the stress at break in appropriate ranges.

[ chemical formula 2]

As the styrene-based resin, a styrene-based resin containing 2 or more copolymers having different structures can be used, and a styrene-based resin containing a styrene-isoprene copolymer and a styrene-isoprene-styrene copolymer in combination can be used.

The styrene-based resin is preferably a styrene-based resin containing the styrene-isoprene copolymer in a range of 0 to 80% by mass, more preferably a styrene-based resin containing the styrene-isoprene copolymer in a range of 0 to 70% by mass, even more preferably a styrene-based resin containing the styrene-isoprene copolymer in a range of 0 to 50% by mass, and even more preferably a styrene-based resin containing the styrene-isoprene copolymer in a range of 0 to 30% by mass, relative to the total mass of the styrene-isoprene copolymer and the styrene-isoprene-styrene copolymer. By setting the above range, it is possible to achieve both excellent elongation at break and excellent stress at break and also excellent thermal durability.

The styrene-isoprene copolymer is preferably a styrene-isoprene copolymer having a weight average molecular weight in a range of 1 to 80 ten thousand, more preferably a styrene-isoprene copolymer having a weight average molecular weight in a range of 3 to 50 ten thousand, and even more preferably a styrene-isoprene copolymer having a weight average molecular weight in a range of 5 to 30 ten thousand, the weight average molecular weight being a weight average molecular weight measured by Gel Permeation Chromatography (GPC) in terms of standard polystyrene (gel permeation chromatography, SC-8020 manufactured by tokyo corporation, high molecular weight column tskgel gmhhr-H, solvent: tetrahydrofuran). By setting the above range, the fluidity under heating and the compatibility upon dilution with a solvent can be secured, and therefore, the adhesive tape is more preferable in terms of good workability in the production process and obtaining an adhesive tape having thermal durability.

The styrene-based resin may be a styrene-based resin having a single structure such as a linear structure, a branched structure, or a multi-branched structure, but a mixture of styrene-based resins having different structures may be used. The styrene-based resin having a rich linear structure imparts excellent elongation at break to the adhesive tape of the present invention. On the other hand, a styrene resin having a branched structure or a multi-branched structure and having a styrene block disposed at a molecular end can have a quasi-crosslinked structure and can impart an excellent cohesive force. Therefore, it is preferable to use them in combination according to the required mechanical properties.

The method for producing the styrene-isoprene-styrene copolymer is not particularly limited, and conventionally known production methods can be applied. For example, the following methods are used: a method of polymerizing a styrene block and an isoprene block in order by an anion living polymerization method; a method for producing a coupled block copolymer by reacting a block copolymer having living active terminals with a coupling agent.

The method for producing the styrene-isoprene copolymer is not particularly limited, and conventionally known production methods can be applied. For example, there is a method of polymerizing a styrene block and an isoprene block in this order by an anionic living polymerization method.

The method for producing the mixture of the styrene-isoprene copolymer and the styrene-isoprene-styrene copolymer is not particularly limited, and conventionally known production methods can be applied. For example, there is a method of mixing the styrene-isoprene copolymer produced as described above with a styrene-isoprene-styrene copolymer. In addition, it can be produced simultaneously in the form of a mixture by one polymerization step. In a more specific embodiment, in the anionic living polymerization method, first, in the first step, a styrene monomer is polymerized in a polymerization solvent using an anionic polymerization initiator to form a polystyrene block having living active terminals. Next, in the second step, isoprene is polymerized from the living active terminal of the polystyrene block to obtain a styrene-isoprene diblock copolymer having a living active terminal. Next, in a third step, a portion of the styrene-isoprene diblock copolymer having an active living end is reacted with a coupling agent to form a coupled styrene-isoprene-styrene block copolymer. Then, in the fourth step, the living active terminal of the remaining part of the styrene-isoprene diblock copolymer having the living active terminal is inactivated by a polymerization terminator to form a styrene-isoprene diblock copolymer.

In addition, a tackifier resin may be used for the base material for the purpose of improving adhesion to the adhesive layer and improving heat resistance. Among them, a tackifier resin having a softening point of 80 ℃ or higher is preferably used, and a softening point of 90 ℃ or higher is more preferably 90 ℃ or higher, further preferably 100 ℃ or higher, and further preferably 110 ℃ or higher. The softening point is a value measured by the method (dry bulb method) defined in JISK 2207.

As the above-mentioned tackifier resin, for example, a tackifier resin which is solid at room temperature (23 ℃) is preferably used, and C can be used₅Petroleum resin, C₅System C₉Petroleum resins such as petroleum resins and alicyclic petroleum resins.

The petroleum resin is easily compatible with the polyisoprene structure constituting the styrene-isoprene copolymer or styrene-isoprene-styrene copolymer, and as a result, the initial adhesion and thermal durability of the pressure-sensitive adhesive tape can be further improved.

As the above-mentioned C₅As the petroleum resin, an aliphatic petroleum resin can be used, and examples thereof include Escorez1202, 1304, 1401 (manufactured by Toyobo chemical Co., Ltd.), Wingtack 95 (manufactured by Goodyear fire and rubber company), Quintone K100, R100, F100 (manufactured by Nippon Rikusho Co., Ltd.), Piccotac 95, and Piccopale100 (manufactured by physicochemical Hercules).

As the above-mentioned C₅System C₉The above-mentioned resin C can be used as the petroleum resin₅Petroleum resin and C₉As the copolymer of a petroleum resin, for example, Escorez 2101 (manufactured by TONEX), Quintone G115 (manufactured by Nippon Ralskii), Hercotac1149 (manufactured by physiochemical Hercules) and the like can be used.

The alicyclic petroleum resin may be the same as C₉Examples of the hydrogenated petroleum resin include Escorez 5300 (manufactured by TONEX), Arkon P-100 (manufactured by Mitsuwa chemical industry), and Regalite R101 (manufactured by physicecech).

The tackifier resin is C₅Petroleum resin, C₅System C₉As the resin other than the petroleum resin and alicyclic petroleum resin, for example, a polymerized rosin resin and C₉Petroleum resin, terpene resin, rosin resin, terpene-phenol resin, styrene resin, coumarone-indene resin, xylene resin, phenol resin, and the like.

Wherein the above-mentioned tackifier resin C is used in combination₅Natural petroleum oilThe resin and the polymerized rosin resin are preferable in terms of achieving both of further excellent initial adhesiveness and thermal durability.

The tackifier resin is preferably used in a range of 0 to 100% by mass, more preferably 0 to 70% by mass, even more preferably 0 to 50% by mass, and even more preferably 0 to 30% by mass, based on the total amount of the styrene-isoprene copolymer and the styrene-isoprene-styrene copolymer. When used in the above range, the adhesive tape can easily improve the interface adhesion between the adhesive layer and the base layer and can achieve both excellent elongation at break and excellent thermal durability.

In addition, in the above-mentioned base material, as necessary, the following substances may be used within a range not impairing the characteristics: additives such as other polymer components, crosslinking agents, anti-aging agents, ultraviolet absorbers, fillers, polymerization inhibitors, surface modifiers, antistatic agents, antifoaming agents, viscosity modifiers, light-resistant stabilizers, weather-resistant stabilizers, heat-resistant stabilizers, antioxidants, leveling agents, organic pigments, inorganic pigments, pigment dispersants, silica beads, organic beads and the like; inorganic fillers such as silica, alumina, titania, zirconia, and antimony pentoxide.

The use of a phenol-based antioxidant as the above antioxidant is preferable because the heat resistance stability of a styrene-isoprene copolymer or the like can be effectively improved, and as a result, an adhesive and an adhesive tape having further excellent heat durability can be obtained while maintaining good initial adhesiveness.

The phenol-based antiaging agent is usually a phenol-based compound having a sterically hindered group, and is typically a monohydric phenol type, a bisphenol type, or a polyphenol type. As specific examples, 2, 6-di-tert-butyl-4-methylphenol, 2 ' -methylenebis (4-methyl-6-tert-butylphenol), 2 ' -methylenebis (4-ethyl-6-tert-butylphenol), 4 ' -thiobis (6-tert-butyl-3-methylphenol), 4, 4 '-butylidenebis- (3-methyl-6-tert-butylphenol), tetrakis- [ methylene-3- (3' 5 '-di-tert-butyl-4-hydroxyphenyl) propionate ] methane, n-octadecyl-3- (4' -hydroxy-3 '5' -di-tert-butylphenyl) propionate and the like are used alone or in combination of 2 or more.

The phenolic antioxidant is preferably used in a range of 0.1 to 5 parts by mass, and 0.5 to 3 parts by mass, per 100 parts by mass of the styrene-isoprene block copolymer, and can effectively improve the heat resistance of the styrene-isoprene copolymer, and as a result, an adhesive having further excellent heat durability can be obtained while maintaining good initial adhesion.

The phenolic antioxidant may be used in combination with other antioxidants such as a phosphorus antioxidant (also referred to as a processing stabilizer), an amine antioxidant, and an imidazole antioxidant, and in particular, the phenolic antioxidant may be used in combination with a phosphorus antioxidant to obtain an adhesive having further excellent heat durability while maintaining good initial adhesion. The phosphorus-based antioxidant may slightly change color (yellow) with time in a high-temperature environment, and therefore the amount of the phosphorus-based antioxidant to be used is preferably set as appropriate in consideration of the balance among the initial adhesiveness, the thermal durability, and the prevention of discoloration.

As a material used for the base material of the pressure-sensitive adhesive tape of the present invention, polyurethane can be suitably used. As the above polyurethane, a reaction product of a polyol (b1-1) and a polyisocyanate (b1-2) can be suitably used.

Examples of the polyol (b1-1) include polyether polyol, polyester polyol, and polycarbonate polyol. Among these, as the polyol (b1-1), a polyester polyol and a polyether polyol may be used alone or in combination of 2 or more to obtain mechanical properties of the substrate. When the heat resistance of the adhesive tape is required, polyester polyol is preferably used, and when water resistance and biodegradability are required, polyether polyol is preferably used.

Examples of the polyester polyol that can be used in the polyol (b1-1) include polyester polyols obtained by esterification of a low molecular weight polyol with a polycarboxylic acid, polyesters obtained by ring-opening polymerization of a cyclic ester compound such as caprolactone, and copolyesters thereof.

Examples of the low molecular weight polyol include aliphatic alkylene glycols such as ethylene glycol, propylene glycol, 1, 4-butanediol, 1, 6-hexanediol, diethylene glycol, neopentyl glycol, and 1, 3-butanediol, and cyclohexanedimethanol, which have a molecular weight of about 50 to 300.

Examples of the polycarboxylic acid that can be used for producing the polyester polyol include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid; and anhydrides or esters thereof.

As the above polyol (b1-1), a polyether polyol can be used. As the polyether polyol, for example, polyether polyols obtained by addition polymerization of alkylene oxides using 1 or 2 or more types of compounds having 2 or more active hydrogen atoms as an initiator can be used.

As the above polyol (b1-1), a polycarbonate polyol can be used. For example, a polycarbonate polyol obtained by reacting a carbonate and/or phosgene with a small-molecular polyol described later can be used.

Examples of the carbonate include methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclic carbonate, and diphenyl carbonate.

Examples of the small molecule polyol which can react with the above-mentioned carbonate and phosgene include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1, 2-propanediol, 1, 3-propanediol, dipropylene glycol, tripropylene glycol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 1, 5-hexanediol, 1, 6-hexanediol, 2, 5-hexanediol, 1, 7-heptanediol, 1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, 1, 11-undecanediol, 1, 12-dodecanediol, 2-methyl-1, 3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1, 3-propanediol, 3-methyl-1, 5-pentanediol, 2-ethyl-1, 3-hexanediol, 2-methyl-1, 8-octanediol, 1, 4-cyclohexanedimethanol, hydroquinone, resorcinol, bisphenol A, bisphenol F, 4' -bisphenol, and the like.

As the polyol (b1-1), other polyols can be used in addition to the above polyols. Examples of the other polyol include acrylic polyols and the like.

As the polyisocyanate (b1-2), alicyclic polyisocyanates, aliphatic polyisocyanates, and aromatic polyisocyanates can be used, and alicyclic polyisocyanates are preferably used.

Examples of the alicyclic polyisocyanate include isophorone diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, 4' -dicyclohexylmethane diisocyanate, 2, 4-and/or 2, 6-methylcyclohexane diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexene-1, 2-dicarboxylate, 2, 5-and/or 2, 6-norbornane diisocyanate, dimer acid diisocyanate, and bicycloheptane triisocyanate, which may be used alone or in combination of 2 or more.

Examples of the method for producing the polyurethane (b1) by reacting the polyol (b1-1) with the polyisocyanate (b1-2) include a method in which the polyol (b1-1) charged into a reaction vessel is heated under normal pressure or reduced pressure to remove moisture, and then the polyisocyanate (b1-2) is supplied and reacted at once or in portions.

The reaction of the polyol (b1-1) and the polyisocyanate (b1-2) is preferably carried out in a range where the equivalent ratio of the isocyanate group of the polyisocyanate (b1-2) to the hydroxyl group of the polyol (b1-1) (hereinafter referred to as "NCO/OH equivalent ratio") is 1.0 to 20.0, more preferably 1.1 to 13.0, still more preferably 1.2 to 5.0, and particularly preferably 1.5 to 3.0.

The reaction conditions (temperature, time, etc.) of the polyol (b1-1) and the polyisocyanate (b1-2) may be appropriately set in consideration of safety, quality, cost, etc., and are not particularly limited, and for example, the reaction temperature is preferably in the range of 70 to 120 ℃, and the reaction time is preferably in the range of 30 minutes to 5 hours.

When the polyol (b1-1) is reacted with the polyisocyanate (b1-2), a tertiary amine catalyst, an organometallic catalyst, or the like can be used as a catalyst, if necessary.

The reaction may be carried out in a solvent-free environment or in the presence of an organic solvent.

Examples of the organic solvent include ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl butyl ketone, and cyclohexanone; ether ester solvents such as methyl cellosolve acetate and butyl cellosolve acetate; aromatic hydrocarbon solvents such as toluene and xylene; amide solvents such as dimethylformamide and dimethylacetamide are used alone or in combination of 2 or more. The organic solvent may be removed by a suitable method such as heating under reduced pressure or drying under normal pressure during the production of the polyurethane resin (b1) or after the production of the polyurethane (b 1).

As the polyurethane (b1) obtained by the above method, a polyurethane having a softening temperature of 40 ℃ or higher is preferably used, and a polyurethane having a softening temperature of 50 ℃ or higher is more preferably used. The softening temperature is a value measured according to JIS K2207. The upper limit of the softening temperature is preferably 100 ℃ or lower.

As the substrate, for the purpose of further improving the adhesion to the pressure-sensitive adhesive layer, a substrate provided with an undercoat layer, a substrate subjected to surface treatment such as surface roughening treatment by sandblasting, solvent treatment or the like, corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone treatment, ultraviolet irradiation treatment, oxidation treatment or the like can be used.

As a method for producing the above-mentioned base material, there are a casting method by extrusion molding, a uniaxial stretching method, a sequential secondary stretching method, a simultaneous biaxial stretching method, a blow molding method, a tube molding method, a rolling method, a solution method, and the like. Among them, a method based on a casting method by extrusion molding, a uniaxial stretching method, a sequential secondary stretching method, a simultaneous biaxial stretching method, a blow molding method, a tube molding method may be suitably used, and it is sufficient to select the method according to the mechanical strength required for the adhesive tape of the present invention.

The substrate may have a single-layer structure, 2-layer structure, 3-layer structure, or a multilayer structure of at least two layers. In the case of a multilayer structure, at least 1 layer is preferably a layer having the above-mentioned resin composition, because the required mechanical properties can be easily exhibited. In addition, a substrate having a 3-layer structure can be obtained by a method of co-extruding a thermoplastic resin such as polypropylene and the styrene-isoprene-styrene copolymer. This may be used as an appropriate configuration in some cases when the pressure-sensitive adhesive tape of the present invention is intended to have, for example, appropriate dimensional stability and elasticity.