KR20170052525A - Double-sided adhesive tape for portable electronic device - Google Patents

Abstract

An object of the present invention is to provide a double-sided pressure-sensitive adhesive tape for portable electronic devices which can exhibit excellent impact resistance after hot pressing even if the width is narrow. A double-sided pressure-sensitive adhesive tape for portable electronic devices having a pressure-sensitive adhesive layer on both surfaces of a substrate, wherein at least one pressure-sensitive adhesive layer comprises a structural unit derived from butyl acrylate in an amount of 45 to 90% 100 parts by weight of an acrylic copolymer containing 5 to 40% by weight of a derived structural unit and having a weight average molecular weight of 400,000 to 1,000,000 and 40 to 60 parts by weight of a tackifier resin and having a shear modulus (G ' ) Is 1.0 × 10 ⁶ to 8.0 × 10 ⁶ Pa, and 40 to 60 parts by weight of the tackifier resin is a double-sided pressure-sensitive adhesive tape for portable electronic devices containing 5 to 30 parts by weight of a tackifier resin (a) having a softening point of 100 ° C. or lower to be.

Description

TECHNICAL FIELD [0001] The present invention relates to a double-sided adhesive tape for portable electronic devices,

The present invention relates to a double-sided pressure-sensitive adhesive tape for portable electronic devices that can exhibit excellent impact resistance after hot pressing even if it is narrow.

BACKGROUND ART In an electronic apparatus (for example, a cellular phone, a portable information terminal, etc.) equipped with an image display apparatus or an input apparatus, an adhesive tape is used for assembly. Specifically, for example, an adhesive tape is used to adhere a cover panel for protecting the surface of an electronic device to a touch panel module or a display panel module, or to adhere a touch panel module and a display panel module. Such an adhesive tape is used, for example, in such a manner as to be punched out in the form of a frame or the like, and arranged around the display screen.

BACKGROUND ART [0002] Adhesive tapes used in electronic devices are required to have various performances including high adhesive force. For example, they are required to have impact resistance that does not peel off even when an impact is applied, and that does not apply a strong impact to the component.

2. Description of the Related Art In recent years, with the miniaturization of electronic apparatuses and the enlargement of the display screen, the area of the openings has been increased, thereby narrowing the junction fixed portions around the display screen. For this reason, the adhesive tape has a narrow width every year, and when used in a narrow width, the adhesive area decreases. If the adhesive area is lowered, it is difficult for the design maker to design the adhesive tape to a desired width, since it becomes difficult for the adhesive tape to reach the acceptance reference value in the adhesive force test and drop impact test in the electronic device design maker.

As an adhesive tape capable of maintaining a high adhesive force even if it is narrow, an adhesive tape made of a thermosensitive adhesive has been studied.

Patent Document 1 discloses a thermosetting film comprising a polymer having a urethane group, an amide group, and an acryl group. Patent Document 2 describes a heat-bonding sheet in which a release film is formed on each surface of a double-sided adhesive sheet having a surface of a thermosensitive adhesive layer made of a polyester-based thermoplastic adhesive on both sides.

However, in general, the heat-sensitive adhesive is weak against impacts as compared with the pressure-sensitive adhesive, and has a problem that it easily peels off when dropped.

Japanese Laid-Open Patent Publication No. 2013-79305 Japanese Patent Application Laid-Open No. 2009-242562

An object of the present invention is to provide a double-sided pressure-sensitive adhesive tape for portable electronic devices which can exhibit excellent impact resistance after hot pressing even if the width is narrow.

A double-sided pressure-sensitive adhesive tape for portable electronic devices having a pressure-sensitive adhesive layer on both surfaces of a substrate, wherein at least one pressure-sensitive adhesive layer comprises a structural unit derived from butyl acrylate in an amount of 45 to 90% 100 parts by weight of an acrylic copolymer containing 5 to 40% by weight of a derived structural unit and having a weight average molecular weight of 400,000 to 1,000,000 and 40 to 60 parts by weight of a tackifier resin and having a shear modulus (G ' ) Is 1.0 × 10 ⁶ to 8.0 × 10 ⁶ Pa, and 40 to 60 parts by weight of the tackifier resin is a double-sided pressure-sensitive adhesive tape for portable electronic devices containing 5 to 30 parts by weight of a tackifier resin (a) having a softening point of 100 ° C. or lower to be.

Hereinafter, the present invention will be described in detail.

The present inventors have found that a double-sided pressure-sensitive adhesive tape for a portable electronic device having a pressure-sensitive adhesive layer on both surfaces of a substrate can be obtained by blending a specified amount of a specific acrylic copolymer and a specific tackifier resin in at least one pressure- Sensitive adhesive tape for portable electronic devices which can exhibit excellent impact resistance after hot pressing even when the shear modulus is narrowed by adjusting the shear modulus (G ') of the double-sided pressure-sensitive adhesive tape in a specific range. .

The double-sided adhesive tape for portable electronic devices of the present invention (also referred to simply as "double-sided adhesive tape" in this specification) has a pressure-sensitive adhesive layer on both sides of the substrate.

In the double-sided pressure-sensitive adhesive tape of the present invention, at least one pressure-sensitive adhesive layer contains 45 to 90% by weight of a structural unit derived from butyl acrylate and 5 to 40% by weight of a structural unit derived from 2-ethylhexyl acrylate , 100 parts by weight of an acrylic copolymer having a weight average molecular weight of 400,000 to 1,000,000, and 40 to 60 parts by weight of a tackifier resin.

When the pressure-sensitive adhesive layer has such a composition, the pressure-sensitive adhesive force and impact resistance of the double-stick pressure-sensitive adhesive tape after hot pressing can be increased.

The acrylic copolymer can be prepared by copolymerizing a monomer mixture.

The monomer mixture includes 45 to 90 parts by weight of butyl acrylate and 5 to 40 parts by weight of 2-ethylhexyl acrylate.

If the content of butyl acrylate is less than 45 parts by weight, the adhesive strength of the double-sided pressure-sensitive adhesive tape after hot pressing is lowered. If the content of butyl acrylate exceeds 90 parts by weight, the double-faced pressure-sensitive adhesive tape easily peels off from the adherend when a strong impact is applied to the adherend.

When the content of 2-ethylhexyl acrylate is less than 5 parts by weight, the double-sided pressure-sensitive adhesive tape easily peels off from the adherend when a strong impact is applied to the adherend. When the content of 2-ethylhexyl acrylate exceeds 40 parts by weight, the adhesive strength of the double-stick adhesive tape after hot pressing is lowered.

The monomer mixture may contain other copolymerizable monomers other than butyl acrylate and 2-ethylhexyl acrylate if necessary.

Examples of other polymerizable monomers that can be copolymerized include monomers having an alkyl group of 1 to 3 carbon atoms such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate and isopropyl (Meth) acrylic acid alkyl ester having 13 to 18 carbon atoms in the alkyl group such as alkyl (meth) acrylate, tridecyl methacrylate and stearyl (meth) acrylate, hydroxyalkyl (meth) acrylate, glycerin dimethacrylate Methacrylic acid, glycidyl methacrylate, 2-methacryloyloxyethyl isocyanate, (meth) acrylic acid, itaconic acid, maleic anhydride, crotonic acid, maleic acid, fumaric acid and the like.

In particular, it is preferable that the monomer mixture further contains less than 20 parts by weight of ethyl acrylate or methyl acrylate based on 100 parts by weight of the total of butyl acrylate and 2-ethylhexyl acrylate. By adding less than 20 parts by weight of ethyl acrylate or methyl acrylate to the monomer mixture, it is possible to increase the adhesive strength of the double-sided pressure-sensitive adhesive tape after hot-pressing and to make it difficult to peel off the adherend when a strong impact is applied to the adhesive surface. The preferable lower limit of the content of ethyl acrylate or methyl acrylate is 5 parts by weight, and the more preferable upper limit is 15 parts by weight.

In order to obtain the acrylic copolymer by copolymerizing the monomer mixture, the monomer mixture may be subjected to a radical reaction in the presence of a polymerization initiator. As the method of radical reaction of the monomer mixture, that is, the polymerization method, conventionally known methods are used, and examples thereof include solution polymerization (non-point polymerization or normal temperature polymerization), emulsion polymerization, suspension polymerization and bulk polymerization .

The polymerization initiator is not particularly limited, and examples thereof include organic peroxides and azo compounds. As the organic peroxide, for example, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, t-hexylperoxy pivalate, t-butyl peroxypivalate, Hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, T-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy laurate, and the like. As the azo compound, for example, azobisisobutyronitrile, azobiscyclohexanecarbonitrile and the like can be given. These polymerization initiators may be used alone or in combination of two or more.

The weight average molecular weight (Mw) of the acrylic copolymer is 400,000 to 1,000,000. If the weight average molecular weight is less than 400,000, the double-sided pressure-sensitive adhesive tape easily peels off from the adherend when a strong impact is applied to the adherend. If the weight average molecular weight exceeds 1 million, the adhesive strength of the double-sided pressure-sensitive adhesive tape after hot pressing is lowered. The lower limit of the weight average molecular weight is preferably 500,000, and the upper limit is preferably 95,000, more preferably 60,000, and still more preferably 90,000.

In order to adjust the weight average molecular weight to the above range, polymerization conditions such as polymerization initiator and polymerization temperature may be adjusted.

The weight average molecular weight (Mw) is a weight average molecular weight in terms of standard polystyrene as measured by Gel Permeation Chromatography (gel permeation chromatography).

The pressure-sensitive adhesive layer contains 40 to 60 parts by weight of a tackifier resin based on 100 parts by weight of the acrylic copolymer.

If the content of the tackifier resin is less than 40 parts by weight, it is difficult for the double-stick adhesive tape to exhibit sufficient adhesive strength after hot pressing. If the content of the tackifier resin exceeds 60 parts by weight, the pressure-sensitive adhesive layer becomes brittle, and the double-sided pressure-sensitive adhesive tape is easily peeled off from the adherend due to an impact such as dropping. The preferable lower limit of the content of the tackifier resin is 45 parts by weight, and the preferable upper limit is 55 parts by weight.

40 to 60 parts by weight of the tackifier resin contains 5 to 30 parts by weight of a tackifier resin (a) having a softening point of 100 ° C or less. The softening point is a softening point measured by the JIS K 2207 circular method.

If the content of the tackifier resin (a) having a softening point of 100 DEG C or less is less than 5 parts by weight, the flexibility of the pressure-sensitive adhesive layer is lowered and the double-sided pressure-sensitive adhesive tape is easily peeled off from the adherend due to impact such as dropping. If the content of the tackifier resin (a) having a softening point of 100 DEG C or lower is more than 30 parts by weight, the pressure-sensitive adhesive layer becomes excessively soft and the double-sided pressure-sensitive adhesive tape hardly exhibits sufficient adhesive strength after hot pressing. The preferable upper limit of the content of the tackifier resin (a) having a softening point of 100 DEG C or lower is 25 parts by weight.

By setting the softening point of the tackifier resin (a) having a softening point of 100 DEG C or lower to 100 DEG C or less, the adhesive force after hot pressing can be increased while maintaining the impact resistance and flexibility of the pressure sensitive adhesive layer.

Among them, the tackifier resin (a) having a softening point of 100 占 폚 or lower is preferably a softening point of 80 占 폚 or lower. By setting the softening point to 80 占 폚 or less, the impact resistance of the pressure-sensitive adhesive layer can be further increased.

The tackifier resin preferably contains a rosin-based tackifier resin and / or a terpene-based tackifier resin. In addition to the rosin-based tackifying resin and / or the terpene-based tackifying resin, examples of the tackifying resin include coumarone-indene resin, alicyclic saturated hydrocarbon resin, C5-based petroleum resin, C9- -C9 synthetic petroleum resin, and the like.

The rosin-based tackifying resin is not particularly limited, but a rosin ester-based resin is preferable. Examples of the rosin ester-based resin include rosin resins mainly composed of abietic acid, disproportionated rosin resins and hydrogenated rosin resins, and dimers of resin acids such as abietic acid (polymerized rosin resin) Is a resin obtained by esterification by a conventional method.

A rosin ester resin, a rosin ester resin, a disproportionated rosin resin esterified, a disproportionated rosin ester resin, an esterified hydrogenated rosin resin, a hydrogenated rosin ester resin, a polymerized rosin resin esterified, a polymerized rosin ester Resin. Examples of the alcohols used for the esterification include polyhydric alcohols such as ethylene glycol, glycerin and pentaerythritol.

As the hydrogenated rosin ester resin, for example, Fine Crystal KE-359 (having a hydroxyl value of 42, a softening temperature of 100 ° C) manufactured by Arakawa Chemical Industries, Ltd., ester gum H (hydroxyl value of 29, have.

As the above-mentioned polymerized rosin ester resin, for example, pendulum D135 (hydroxyl value of 45, softening temperature of 135 占 폚) manufactured by Arakawa Chemical Industries, Ltd., pennel D130 (hydroxyl value of 45, softening temperature of 130 占 폚) 34, a softening temperature of 125 占 폚), Phenel D160 manufactured by the same company (hydroxyl value of 42, softening temperature of 160 占 폚) and the like.

These rosin-based tackifying resins may be used alone or in combination of two or more.

The terpene-based tackifier resin is not particularly limited, but terpene phenolic resin is preferable. The terpene phenolic resin is a resin obtained by polymerizing terpene in the presence of phenol.

YS Polystar G150 (softening point: 150 占 폚), YS Polystar T100 (softening point: 100 占 폚) manufactured by Yasuhara Chemical Co., Ltd., YS Polystar G125 (softening point: 125 占 폚) manufactured by Yasuhara Chemical Co., Ltd. is used as the terpene type tackifier resin. , YS Polystar T115 (softening point 115 캜), and YS Polystar T130 (softening point 130 캜) manufactured by the same company.

It is preferable that the pressure-sensitive adhesive layer has a cross-linking structure formed between the main chains of the resin (the acrylic copolymer and / or the tackifier resin) constituting the pressure-sensitive adhesive layer by the addition of the cross-linking agent.

The crosslinking agent is not particularly limited, and examples thereof include an isocyanate crosslinking agent, an aziridine crosslinking agent, an epoxy crosslinking agent, and a metal chelate crosslinking agent. Of these, isocyanate-based crosslinking agents are preferred. When the isocyanate-based crosslinking agent is added to the pressure-sensitive adhesive layer, the isocyanate group of the isocyanate-based crosslinking agent reacts with the alcoholic hydroxyl group in the resin constituting the pressure-sensitive adhesive layer, and the crosslinking of the pressure-sensitive adhesive layer is loosened. Therefore, the pressure-sensitive adhesive layer can disperse the exfoliation stress applied intermittently, and the exfoliation resistance from the adherend is further improved against the exfoliation stress caused by the deformation of the adherend when a strong impact is applied.

The amount of the crosslinking agent to be added is preferably 0.1 to 15 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the acrylic copolymer.

If the crosslinking degree (gel fraction) of the pressure-sensitive adhesive layer is too high or too low, the pressure-sensitive adhesive layer may easily peel off from the adherend due to the peeling stress caused by the deformation of the adherend. By weight, more preferably from 10 to 50% by weight, and particularly preferably from 20 to 45% by weight.

The crosslinking degree (gel fraction) of the pressure-sensitive adhesive layer was obtained by taking W1 (g) as a pressure-sensitive adhesive layer and immersing the pressure-sensitive adhesive layer in ethyl acetate at 23 DEG C for 24 hours to filter the insoluble fractions with a wire mesh of 200 mesh, (G) of the dried residue is measured, and is calculated by the following formula (1).

Crosslinking degree (gel fraction) (% by weight) = 100 x W2 / W1 (1)

The pressure-sensitive adhesive layer has a shear modulus (G ') at 23 ° C of 1.0 × 10 ⁶ to 8.0 × 10 ⁶ Pa. By adjusting the shear modulus (G ') of the pressure-sensitive adhesive layer at 23 DEG C within the above range, the impact resistance at room temperature of the double-stick adhesive tape can be increased.

When the shear modulus (G ') at 23 DEG C is less than 1.0 x 10 < ⁶ > Pa, it is difficult for the double-stick adhesive tape to exhibit sufficient adhesive force after hot pressing. If the shear modulus (G ') at 23 DEG C exceeds 8.0 x 10 < ⁶ > Pa, the flexibility of the pressure-sensitive adhesive layer is lowered, and the double-sided pressure-sensitive adhesive tape is easily peeled off from the adherend due to impact such as dropping. In addition, the initial tackiness of the pressure-sensitive adhesive layer is lowered, and the adhesive force to the release paper bonded to the pressure-sensitive adhesive layer at the time of punching the double-sided pressure-sensitive adhesive tape is lowered and the workability is significantly lowered. The preferable lower limit of the shear modulus (G ') at 23 ° C is 1.1 × 10 ⁶ Pa and the upper limit is 7.0 × 10 ⁶ Pa. More preferably, the lower limit is 1.2 × 10 ⁶ Pa and the upper limit is 6.0 × 10 ⁶ Pa to be.

The shear modulus (G ') at 23 ° C is a value measured at a measurement frequency of 10 Hz, for example, using DVA-200 manufactured by Haitian Instrumentation Control Co., Ltd.

In order to adjust the shear modulus (G ') of the pressure-sensitive adhesive layer at 23 ° C within the above range, the composition of the pressure-sensitive adhesive layer may be adjusted within the range described above.

The pressure-sensitive adhesive layer may be colored for the purpose of shielding light from a display screen such as a liquid crystal display (LCD). The coloring pigment used for coloring the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include carbon black and titanium oxide.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but it is preferable that the thickness of the pressure-sensitive adhesive layer (thickness of the pressure-sensitive adhesive layer on one side) is 10 to 150 占 퐉. If the thickness is less than 10 占 퐉, the pressure-sensitive adhesive layer may have reduced impact resistance. When the thickness is more than 150 占 퐉, the pressure-sensitive adhesive layer may have poor reworkability or workability.

In the double-sided pressure-sensitive adhesive tape of the present invention, if at least one pressure-sensitive adhesive layer is the above-mentioned pressure-sensitive adhesive layer, the pressure-sensitive adhesive layers on both sides may be the same composition or may be different compositions.

The substrate is not particularly limited, and examples thereof include a resin film having relatively high rigidity, a resin film having relatively low rigidity, a sheet-like foam, and the like.

The resin film having a relatively high rigidity is not particularly limited, and examples thereof include a polyethylene terephthalate (PET) film and an axially oriented polypropylene (OPP) film. The double-sided pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer as described above. Even in the case of the resin film having a relatively high rigidity and a low impact absorbing property of the substrate, Lt; / RTI >

The thickness of the resin film having a relatively high rigidity is not particularly limited, but is preferably 5 to 100 占 퐉. If the thickness is less than 5 占 퐉, the base material may be destroyed when the strength is lowered and a strong impact is applied, or the punching workability may be deteriorated. If the thickness exceeds 100 m, the substrate may be deteriorated in flexibility and peeled off at the interface with the pressure-sensitive adhesive layer in the case where a strong impact is applied, and the double-sided pressure-sensitive adhesive tape may be adhered So that it is sometimes difficult to coalesce them.

When the base material is a resin film or a sheet-like foam having a relatively low rigidity, since the base material itself has buffering properties, the impact resistance of the double-sided pressure-sensitive adhesive tape can be further increased.

The resin film having a relatively low rigidity is not particularly limited, and examples thereof include a rubber-based or urethane-based resin film.

As the sheet-like foam, a polyolefin foam is particularly preferable.

The polyolefin foam is not particularly limited as long as it is a foam containing a polyolefin resin. Examples thereof include a polyethylene foam, a polypropylene foam and an ethylene-propylene foam. From the standpoint of improving impact resistance, (Referred to as " metallocene-based polyolefin foam " in the present specification) containing a polyolefin-based resin obtained by using a metallocene compound containing a tetravalent transition metal as a polymerization catalyst is preferable. Among them, foams (also referred to as " metallocene polyethylene foams " in the present specification) containing a polyethylene resin obtained by using a metallocene compound are more preferable.

As the metallocene compound, for example, a Kaminsky catalyst can be given.

As the polyethylene resin obtained by using the metallocene compound contained in the metallocene polyethylene foam, for example, the metallocene compound may be used to copolymerize ethylene and other? -Olefins optionally mixed with each other And the like. Examples of the other? -Olefins include propene, 1-butene, 1-pentene, 1-hexene and the like.

The metallocene-based polyethylene foam may further contain another olefin-based resin in addition to the polyethylene-based resin obtained by using the metallocene compound. Examples of the other olefin-based resins include polyethylene, polypropylene, ethylene-propylene copolymer, and the like.

In this case, the content of the polyethylene-based resin obtained by using the metallocene compound in the metallocene-based polyethylene foam is preferably 40% by weight or more. When the content of the polyethylene resin obtained by using the metallocene compound is 40 wt% or more, high compressive strength can be obtained even if the thickness of the metallocene polyethylene foam is small.

The polyolefin foam is preferably crosslinked. By crosslinking the polyolefin foam, the impact resistance can be improved.

The method of crosslinking the polyolefin foam is not particularly limited, and examples thereof include a method of irradiating the polyolefin foam with ionizing radiation such as electron beam,? -Ray,? -Ray and? -Ray, And a method of decomposing the peroxide by heating.

The method of producing the polyolefin foam is not particularly limited, but it is also possible to prepare a foamable resin composition containing a polyolefin resin and a foaming agent, foaming the foaming agent when extruding the foamable resin composition into a sheet using an extruder, A method of crosslinking the foamed material as required is preferred.

The thickness of the sheet-form foam is not particularly limited, but is preferably 60 to 300 占 퐉. If the thickness is less than 60 占 퐉, the base material may be destroyed when the strength is lowered and a strong impact is applied. If the thickness exceeds 300 탆, the base material may be deteriorated in flexibility and peeled off at the interface with the pressure-sensitive adhesive layer when a strong impact is applied, and the double-sided pressure-sensitive adhesive tape may be brought into close contact with the adherend There is a case that it becomes difficult to assemble.

The double-faced pressure-sensitive adhesive tape of the present invention preferably has a pushing strength of 120 N or more at room temperature after being punched out in a frame shape with a width of 1 mm and heat-pressed on an aluminum plate at 70 占 폚.

When the push adhesion is within the above range, the adhesive force equal to or larger than the adhesive strength at the width of 2 mm of the double-sided adhesive tape made of a normal pressure-sensitive adhesive can be achieved with a half width (1 mm width) The double-sided pressure-sensitive adhesive tape is likely to reach the acceptance reference value in an adhesive force test or drop impact test in an electronic device design maker. Further, since the double-sided adhesive tape is strongly adhered, lifting or peeling of an adherend (for example, a front face plate (cover panel) or a part) over time can be suppressed. The push adhesion is more preferably 125 N or more, and more preferably 130 N or more.

In addition, the push adhesion at room temperature after punching in a frame of 1 mm in width and heating and pressing on an aluminum plate at 70 占 폚 is a value measured by the method shown in Fig. 2 as described below.

2 is a schematic view of a push test of a double-sided pressure-sensitive adhesive tape. First, a double-faced pressure-sensitive adhesive tape is punched out with an outer diameter of 46 mm in length, 61 mm in length, and 44 mm in inner diameter and 59 mm in length, to produce a frame-shaped test piece having a width of 1 mm. Subsequently, as shown in Fig. 2 (a), a test piece 1 having a release liner removed from a polycarbonate plate 3 having a thickness of 2 mm and a square hole having a width of 38 mm and a length of 50 mm was formed at the center, An aluminum plate 5 having a width of 55 mm, a length of 65 mm and a thickness of 2 mm was attached from the upper surface of the test piece 1 so that the test piece 1 was positioned substantially at the center of the test piece 1, Assemble.

Thereafter, a pressure of 30 kgf was applied at 70 DEG C for 10 seconds from the aluminum plate 5 located on the upper surface of the test apparatus, and the aluminum plate and the polycarbonate plate positioned above and below were heated and bonded to each other. do.

2 (b), the manufactured test apparatus was turned upside down and fixed to the support, and the lower aluminum plate 5 was pressed at a rate of 10 mm / min from the opening side, Can be carried out by measuring the load when the cover 5 is peeled off. The measurement temperature is not particularly limited as long as it is room temperature, and for example, 23 deg.

In the double-sided pressure-sensitive adhesive tape of the present invention, the total thickness of the double-sided pressure-sensitive adhesive tape is preferably 100 to 400 탆. If the total thickness is less than 100 占 퐉, the double-sided pressure-sensitive adhesive tape may be deteriorated in impact resistance. If the total thickness exceeds 400 占 퐉, the double-sided pressure-sensitive adhesive tape may not be suitable for use for fixing the components constituting the electronic apparatus to the apparatus main body.

As a method for producing the double-faced pressure-sensitive adhesive tape of the present invention, for example, the following methods can be mentioned.

First, a solution of the pressure-sensitive adhesive A is prepared by adding a solvent to an acrylic copolymer, a tackifier resin and a crosslinking agent as required, and the solution of the pressure-sensitive adhesive A is coated on the release-treated surface of the release film, To form a pressure-sensitive adhesive layer (A). Next, the substrate is bonded to the surface of the pressure-sensitive adhesive layer A formed.

Next, a release film different from the release film was prepared, a solution of the pressure-sensitive adhesive B was applied to the release-treated surface of the release film, and the solvent in the solution was completely dried to remove the pressure- A film is prepared. The obtained laminated film is laminated on the back surface of the base material on which the pressure-sensitive adhesive layer A is formed, and the pressure-sensitive adhesive layer B is opposed to the back surface of the base material. The double-sided pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer on both sides of the substrate and the surface of the pressure-sensitive adhesive layer covered with the release film can be obtained by pressing the laminate with a rubber roller or the like.

In addition, two sets of laminated films were prepared in the same manner, and these laminated films were laminated on both sides of the substrate respectively with the pressure-sensitive adhesive layer of the laminated film being opposed to the substrate to produce a laminate. Sensitive adhesive tape having a pressure-sensitive adhesive layer on both surfaces of the substrate and the surface of the pressure-sensitive adhesive layer covered with the release film may be obtained.

The use of the double-sided pressure-sensitive adhesive tape of the present invention is not particularly limited, but it is preferable to use a component that constitutes an electronic device (for example, a cellular phone, a portable information terminal, etc.) Specifically, the double-sided adhesive tape of the present invention can be used, for example, as a double-sided adhesive tape for adhering and fixing a liquid crystal display panel of an electronic device (for example, a cellular phone, a portable information terminal, etc.)

The shape of the double-faced pressure-sensitive adhesive tape of the present invention in these applications is not particularly limited, and examples thereof include a rectangular, a frame, a circle, an ellipse, and a donut.

According to the present invention, it is possible to provide a double-sided pressure-sensitive adhesive tape for portable electronic apparatus which can exhibit excellent impact resistance after hot pressing even if the width is narrow.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram of a drop impact test of a double-sided pressure-sensitive adhesive tape. Fig.
2 is a schematic diagram of a push test of a double-sided pressure-sensitive adhesive tape.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Example 1)

(1) Preparation of a pressure-sensitive adhesive solution

The monomer shown in Table 1 and ethyl acetate were added to a reactor equipped with a thermometer, a stirrer, and a cooling tube, and after nitrogen replacement, the reactor was heated to initiate reflux. Subsequently, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added to the reactor. And refluxed at 70 DEG C for 5 hours to obtain a solution of the acrylic copolymer. The obtained acrylic copolymer was measured for its weight average molecular weight by GPC method using "2690 Separations Model" manufactured by Water Corporation as a column.

To 100 parts by weight of the solid content of the acrylic copolymer contained in the obtained acrylic copolymer solution, a predetermined amount of a tackifier resin shown in Table 1 was added and 125 parts by weight of ethyl acetate was added and stirred. Isocyanate crosslinking agent (" Colonate L-45 " manufactured by Nippon Polyurethane Industry Co., Ltd.) was added and stirred to obtain a pressure-sensitive adhesive solution in which the acrylic pressure-sensitive adhesive was dissolved in ethyl acetate.

The tackifier resins used in Examples and Comparative Examples are shown below.

(Tackifier resin (a) having a softening point of 100 DEG C or lower)

Hydrogenated rosin ester resin A (trade name "Ester Gum H", product of Arakawa Chemical Industries, Ltd., softening point 68 ° C)

· Disproportionated rosin ester resin B (trade name "SUPERESTER A-75" manufactured by Arakawa Chemical Industries, Ltd., softening point 75 ° C.)

Hydrogenated rosin ester resin C (manufactured by Arakawa Chemical Industries, Ltd., trade name " ester gel HP ", softening point 80 ° C)

Hydrogenated rosin ester resin D (Fine Crystal KE-359, manufactured by Arakawa Chemical Industries, Ltd., softening point 100 캜)

(Other tackifying resin)

· Disproportionated rosin ester resin E (trade name "SUPERESTER A-115" manufactured by Arakawa Chemical Industries, Ltd., softening point 115 ° C.)

Polymerized rosin ester resin F (trade name: PENCEL D-135, manufactured by Arakawa Chemical Industries, Ltd., softening point: 135 ° C)

Polymerized rosin ester resin G (trade name " PENCEL D-160 ", product of Arakawa Chemical Industries, Ltd., softening point 160 DEG C)

· Terpene phenol resin H (trade name "YS POLYSTAR T130" manufactured by Yasuhara Chemical Co., Ltd., softening point 130 ° C.)

Terpene phenol resin I (manufactured by Yasuhara Chemical Co., Ltd., trade name: " Mighties G150 ", softening point: 150 캜)

(2) Production of double-sided adhesive tape

The resultant pressure-sensitive adhesive solution was coated on the release-treated surface of a 75 占 퐉 -thick PET film subjected to release molding and dried at 110 占 폚 for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 90 占 퐉. On the surface of the formed pressure-sensitive adhesive layer, a PET film " FE2002 " having a thickness of 23 占 퐉 manufactured by Futamura Chemical Industries, Ltd., was laminated with a silicone roller to obtain a single-sided pressure-sensitive adhesive tape having a pressure-

Subsequently, a PET film having a thickness of 75 탆 in which a separate mold-releasing treatment was carried out was prepared, the pressure-sensitive adhesive solution was coated on the release-treated surface of the PET film, and the PET film was dried at 110 캜 for 3 minutes to form a pressure- . This pressure-sensitive adhesive layer was applied to the base material (PET film " FE2002 ") of the single-sided pressure-sensitive adhesive tape prepared above with a silicone roller. As a result, a double-faced pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on both surfaces of the substrate and covered with a PET film having a thickness of 75 탆 and subjected to releasing treatment on the surface of the pressure-sensitive adhesive layer was obtained.

The shear modulus (G ') of the pressure-sensitive adhesive layer was measured by a DVA-200 manufactured by Haitian Instrumentation Control Co., Ltd. at 23 ° C and a frequency of 10 Hz. W1 (g) of the formed pressure-sensitive adhesive layer was sampled, and the pressure-sensitive adhesive layer was immersed in ethyl acetate at 23 DEG C for 24 hours to insolubilize the insoluble matter with a wire mesh of 200 mesh. The residue of the wire net was vacuum- W2 (g) was measured, and the degree of crosslinking (gel fraction) of the pressure-sensitive adhesive layer was calculated by the following formula (1).

Crosslinking degree (gel fraction) (% by weight) = 100 x W2 / W1 (1)

(Examples 2 to 14 and Comparative Examples 1 to 12)

A double-faced pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the acrylic copolymer having the monomer blend and the weight average molecular weight shown in Tables 1 and 2 and the tackifier resin and crosslinking agent described in Tables 1 and 2 were added.

(Example 15)

Except that the substrate was changed to a polyethylene foam "Volara XLH-0180015" (thickness 150 μm) manufactured by Sekisui Chemical Co., Ltd., and the thickness of the pressure-sensitive adhesive layer was changed to 50 μm, I got a tape.

<Evaluation>

The double-sided pressure-sensitive adhesive tape obtained in the Examples and Comparative Examples was evaluated as follows. The evaluation results are shown in Tables 1 and 2.

(1) Drop impact test

(Preparation of test apparatus)

1 is a schematic view of a drop impact test of a double-sided pressure-sensitive adhesive tape. The double-faced pressure-sensitive adhesive tape thus obtained was punched out with an outer diameter of 46 mm, a length of 61 mm, an inner diameter of 44 mm, and a length of 59 mm to prepare a frame-shaped test piece having a width of 1 mm. Subsequently, as shown in Fig. 1 (a), a test piece 1 having a release liner removed from a polycarbonate plate 3 having a thickness of 2 mm and a square hole having a width of 38 mm and a length of 50 mm was formed at the center, A polycarbonate plate 2 having a width of 55 mm, a length of 65 mm and a thickness of 1 mm was attached from the upper surface of the test piece 1 so that the test piece 1 was positioned substantially at the center of the test piece 1, .

Thereafter, a pressure of 30 kgf at 110 DEG C was applied from the side of the polycarbonate plate 2 located on the upper side of the test apparatus for 10 seconds, and the polycarbonate plate placed above and below and the test piece were heated and pressed, and left at room temperature for 24 hours.

(Judgment of drop impact test)

As shown in Fig. 1 (b), the manufactured test apparatus was turned upside down and fixed to a support, and a steel ball 4 having a weight of 300 g sized to pass through a square hole was dropped through a square hole. The height at which the steel ball was dropped was gradually increased and the height at which the steel ball dropped when the test piece and the polycarbonate plate were peeled off by impact applied by dropping the steel ball was measured.

◎: 60 cm or more

○: 50 cm or more and less than 60 cm

?: 40 cm or more and less than 50 cm

X: Less than 40 cm

(2) Push test

(Preparation of test apparatus)

2 is a schematic view of a push test of a double-sided pressure-sensitive adhesive tape. The double-faced pressure-sensitive adhesive tape thus obtained was punched out with an outer diameter of 46 mm, a length of 61 mm, an inner diameter of 44 mm, and a length of 59 mm to prepare a frame-shaped test piece having a width of 1 mm. Subsequently, as shown in Fig. 2 (a), a test piece 1 having a release liner removed from a polycarbonate plate 3 having a thickness of 2 mm and a square hole having a width of 38 mm and a length of 50 mm was formed at the center, An aluminum plate 5 having a width of 55 mm, a length of 65 mm and a thickness of 2 mm was attached from the upper surface of the test piece 1 so that the test piece 1 was positioned substantially at the center of the test piece 1, Assembled.

Thereafter, a pressure of 30 kgf was applied at 70 DEG C for 10 seconds from the aluminum plate 5 located on the upper surface of the test apparatus, and the aluminum plate and the polycarbonate plate positioned above and below were heated and bonded to each other. Respectively.

(Judgment of push test)

As shown in Fig. 2 (b), the manufactured test apparatus was turned upside down and fixed to a support, and the aluminum plate 5 on the lower surface was pressed at a rate of 10 mm / min from the opening side. When the aluminum plate 5 was peeled off Were measured. The measurement was carried out at 23 占 폚.

◎: Above 130 N

○: 120 N or more and less than 130 N

?: 110 N or more and less than 120 N

X: less than 110 N

Industrial availability

According to the present invention, it is possible to provide a double-sided pressure-sensitive adhesive tape for portable electronic apparatus which can exhibit excellent impact resistance after hot pressing even if the width is narrow.

1: Specimen (frame)
2: Polycarbonate plate (thickness: 1 mm)
3: Polycarbonate plate (thickness: 2 mm)
4: Iron (300 g)
5: Aluminum plate (thickness 2 mm)

Claims (4)

A double-sided pressure-sensitive adhesive tape for portable electronic devices having a pressure-sensitive adhesive layer on both sides of a substrate,
At least one of the pressure-sensitive adhesive layers contains 45 to 90% by weight of a structural unit derived from butyl acrylate and 5 to 40% by weight of a structural unit derived from 2-ethylhexyl acrylate, and has a weight- and all men acrylic copolymer 100 parts by weight of a tackifying resin containing from 40 to 60 parts by weight of a shear modulus at 23 ℃ (G ') is ^{1.0 × 10 6 ~ 8.0 × 10} 6 ㎩,
And 40 to 60 parts by weight of the tackifier resin contains 5 to 30 parts by weight of a tackifier resin (a) having a softening point of 100 ° C or less. The method according to claim 1,
Sensitive adhesive tape (a) having a softening point of 100 占 폚 or less has a softening point of 80 占 폚 or less. 3. The method according to claim 1 or 2,
A double-sided pressure-sensitive adhesive tape for portable electronic devices, characterized in that the pressure-sensitive adhesive resin contains a rosin-based pressure-sensitive adhesive resin and / or a terpene-based pressure-sensitive adhesive resin. The method according to any one of claims 1, 2, and 3,
Sided pressure-sensitive adhesive tape for portable electronic devices characterized in that the pressure-sensitive adhesive force at room temperature after hot-pressing on an aluminum plate at 70 ° C is 120 N or more.

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