KR20170094114A - Shock absorbing sheet, shock absorbing adhesive sheet, double-sided shock absorbing adhesive sheet for affixing front plate, double-sided shock absorbing adhesive sheet for affixing back plate, and double-sided shock absorbing adhesive sheet for affixing backlight unit - Google Patents

Abstract

The present invention provides an impact-absorbing sheet having excellent impact resistance, which is preferably used as a base material of a pressure-sensitive adhesive sheet for adhering and fixing a component constituting a portable electronic device to an apparatus main body. Another object of the present invention is to provide a shock-absorbing adhesive sheet having the shock-absorbing sheet, a shock-absorbing double-sided adhesive sheet for fixing the front plate, a shock-absorbing double-sided adhesive sheet for fixing the back plate, and a shock- . The present invention is an impact absorbing sheet having at least one layer of an impact absorbing layer having a maximum value of loss tangent tan delta of at least 0.84 at a frequency of 1.0 x 10 ⁴ to 1.0 x 10 ^6.5 Hz at 23 캜.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorbing double-faced pressure-sensitive adhesive sheet for shock-absorbing double-faced pressure-sensitive adhesive sheets for shock-absorbing pressure-sensitive adhesive sheets, -SIDED SHOCK ABSORBING ADHESIVE SHEET FOR AFFIXING FRONT PLATE, DOUBLE-SIDED SHOCK ABSORBING ADHESIVE SHEET FOR AFFIXING BACK PLATE, AND DOUBLE-SIDED SHOCK ABSORBING ADHESIVE SHEET FOR AFFIXING BACKLIGHT UNIT}

The present invention relates to an impact-absorbing sheet having excellent impact resistance, which is preferably used as a base material of a pressure-sensitive adhesive sheet for sticking and fixing a component constituting a portable electronic device to an apparatus main body. The present invention also relates to a shock-absorbing adhesive sheet having the impact-absorbing sheet, a shock-absorbing double-faced adhesive sheet for fixing the front plate, a shock-absorbing double-faced adhesive sheet for fixing the back plate, and a shock-absorbing double-faced adhesive sheet for fixing the backlight unit.

BACKGROUND ART In a portable electronic device (for example, a cellular phone, a portable information terminal, etc.) equipped with an image display device or an input device, an adhesive tape is used for assembly. Specifically, for example, in order to adhere the front panel (cover panel) for protecting the surface of the portable electronic device to the touch panel module or the display panel module, or to adhere the touch panel module to the display panel module, . Such a pressure-sensitive 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 to be disposed in the periphery of the display screen (for example, Patent Documents 1 and 2).

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

As a method for improving the impact resistance of the adhesive tape, for example, there is a method of using a buffering base material such as a foam. Patent Document 3 discloses a pressure-sensitive adhesive sheet for electronic equipment comprising a crosslinked polyolefin-based resin foam sheet and a specific acrylic pressure-sensitive adhesive layer laminated and integrated on one surface of the crosslinked polyolefin-based resin foam sheet.

BACKGROUND ART [0002] In recent years, with the increase in the size of portable electronic devices, the size of adhesive tapes has been increasing. In addition, since the adhesive tape is used in the form of a frame or the like, narrowing of the adhesive tape is also progressing. For this reason, in a pressure-sensitive adhesive sheet based on a foam as described in Patent Document 3, a problem that peeling off of the pressure-sensitive adhesive tape is likely to occur when an impact such as dropping is applied.

Japanese Laid-Open Patent Publication No. 2011-081213 Japanese Laid-Open Patent Publication No. 2003-337656 Japanese Laid-Open Patent Publication No. 2011-168727

An object of the present invention is to provide an impact-absorbing sheet having excellent impact resistance, which is preferably used as a base material of a pressure-sensitive adhesive sheet to which components constituting a portable electronic device are adhesively fixed to an apparatus main body. The present invention also provides an impact-absorbing adhesive sheet having the impact-absorbing sheet, a shock-absorbing double-faced pressure-sensitive adhesive sheet for fixing the front plate, a shock-absorbing double-faced pressure-sensitive adhesive sheet for fixing the back plate, and a shock- The purpose.

The present invention is an impact absorbing sheet having at least one layer of an impact absorbing layer having a maximum value of loss tangent tan delta of at least 0.84 at a frequency of 1.0 x 10 ⁴ to 1.0 x 10 ^6.5 Hz at 23 캜.

Hereinafter, the present invention will be described in detail.

As a method for improving the impact resistance of a foamed sheet in a pressure-sensitive adhesive sheet based on a foam as described in Patent Document 3, for example, a method of lowering the expansion ratio of the foam and raising the density can be mentioned. However, it is technically difficult to lower the expansion ratio below a certain value, and when the expansion ratio is excessively lowered, the foam becomes closer to the non-foamed material, resulting in impaired flexibility and impact resistance. Therefore, in the pressure-sensitive adhesive sheet based on the conventional foam as described in Patent Document 3, it is difficult to achieve excellent impact resistance in the pressure-sensitive adhesive tape on which narrowing (for example, a width of 1.0 mm or less) is advanced.

The present inventors have found that the impact-absorbing sheet preferably used as the base material of the pressure-sensitive adhesive sheet has an impact-absorbing layer in which the maximum value of the loss tangent tan delta at a specific frequency at 23 DEG C is adjusted to a specific value or more, Even when an impact such as dropping is applied, the energy due to the impact is effectively dissipated as heat or deformation, and peeling is suppressed, thereby completing the present invention.

The impact-absorbing sheet of the present invention has at least one shock absorbing layer having a maximum value of loss tangent tan? Of 0.84 or more at a frequency of 1.0 x 10 ⁴ to 1.0 x 10 ^6.5 Hz at 23 占 폚.

By providing the impact-absorbing sheet of the present invention with the above-described impact-absorbing layer, even when an impact such as dropping is applied to the impact-absorbing sheet, the energy due to the impact is effectively diverged as heat or deformation, and peeling is suppressed. The maximum value of the loss tangent tan? Is preferably 1.31 or more, more preferably 1.50 or more, further preferably 1.80 or more, and particularly preferably 2.00 or more.

Although the upper limit of the maximum value of the loss tangent tan? Is not particularly limited, if the maximum value of the loss tangent tan? Is excessively large due to a large amount of viscous components in the impact absorbing layer, the impact absorbing layer tends to be plastically deformed when the impact is absorbed Therefore, a preferable upper limit is 3.0, and a more preferable upper limit is 2.7.

The maximum value of the loss tangent tan? At a frequency of 1.0 x 10 ⁴ to 1.0 x 10 ^6.5 Hz at 23 占 폚 was measured using a dynamic viscoelasticity measuring apparatus (for example, Rheogel-E4000 manufactured by Ubi EM) , And the master curve is synthesized. At this time, the " maximum value " of the loss tangent tan delta does not necessarily have to be within the range of the frequency of 1.0 x 10 ⁴ to 1.0 x 10 ^6.5 Hz. However, the " maximum value " is within the range of 1.0 x 10 < ⁴ > to 1.0 x 10 < ^6.5 > Hz and thus the impact absorbing sheet can stably absorb shock even when an impact is applied to the shock absorbing sheet at a temperature higher than 23 deg. Loses.

Here, the frequency is 1.0 x 10 ⁴ to 1.0 x 10 ^6.5 Hz, which means that when the impact-absorbing sheet is allowed to fall freely at a height of a few tens of centimeters to a meter and a few tens of centimeters, the impact-absorbing sheet is displaced by several micrometers to tens of micrometers (I.e., a frequency assuming that an impact such as a drop is applied to the portable electronic device).

In order to adjust the maximum value of the loss tangent tan delta to the above range, the composition of the impact absorbing layer may be adjusted within a range described later, but it is preferable that the impact absorbing layer contains an elastomer.

The impact absorbing layer is not particularly limited and may be a foam such as a crosslinked polyolefin foam. In order to adjust the maximum value of the loss tangent tan? Within the above range, a non-foam containing an elastomer or the like is preferable.

Examples of the elastomer include a styrene elastomer, an acrylic elastomer, a urethane elastomer, an ester elastomer, an olefin elastomer, a vinyl chloride elastomer, and an amide elastomer. These elastomers may be used alone or in combination of two or more. Among them, the elastomer is preferably a styrene elastomer, an olefin elastomer, an acrylic elastomer or a urethane elastomer, more preferably a styrene elastomer, in order to adjust the maximum value of the loss tangent tan?

The styrene-based elastomer is not particularly limited as long as it has rubber elasticity at room temperature. It is preferable that the styrene-based elastomer is a block copolymer of a polystyrene layer called a hard segment and a soft segment of ethylene-butylene, ethylene-propylene, ethylene-butadiene, Or a styrene-based elastomer having a triblock structure is more preferable.

Specific examples of the styrene elastomer include styrene-butadiene-styrene (SBS) block copolymer, styrene-butadiene-butylene-styrene (SBBS) block copolymer, styrene-ethylene- ) Block copolymers, hydrogenated styrene-butylene rubbers (HSBR), styrene-ethylene-propylene-styrene (SEPS) block copolymers, styrene-isobutylene-styrene (SIBS) block copolymers, styrene-isoprene- SIS) block copolymer. Of these, SEBS and SEPS are more preferable because they do not have double bonds in the molecular structure and are relatively stable to heat and light.

The styrene content of the styrene-based elastomer is not particularly limited, but the lower limit is preferably 3% by weight and the upper limit is preferably 30% by weight. If the styrene content is less than 3% by weight, heat resistance or cohesive force of the impact absorbing layer may be lowered. If the styrene content is more than 30% by weight, the flexibility of the styrene elastomer is impaired and the maximum value of the loss tangent tan? Is lowered and the impact resistance of the impact absorbing sheet may be lowered. A more preferable lower limit of the styrene content is 4 wt%, and a more preferable upper limit is 25 wt%, more preferably 5 wt%, and still more preferably 20 wt%.

The content of each block such as styrene in the styrene-based elastomer can be measured by ¹ H-NMR (1H-nuclear magnetic resonance) measurement or by ¹³ C-NMR.

The content of the ethylene skeleton in the soft segment of the styrene-based elastomer is not particularly limited, but a preferable upper limit of the soft segment is 100% by weight and 60% by weight. If the content of the ethylene skeleton exceeds 60% by weight, crystallization of the styrene-based elastomer proceeds and flexibility is impaired. Therefore, the maximum value of the loss tangent tan? Decreases and the impact resistance of the impact- have. A more preferable upper limit of the content of the ethylene skeleton is 50% by weight, and a more preferable upper limit is 40% by weight.

Particularly when the styrene elastomer is SEBS or HSBR, it is preferable that the content of the ethylene skeleton in the soft segment is within the above range. When the styrene elastomer is SEBS or HSBR, the content of the ethylene skeleton in the soft segment is preferably 3% by weight or more, more preferably 4% by weight or more, and still more preferably 5% by weight or more. When the content of the ethylene skeleton is 3 wt% or more when the styrene elastomer is SEBS or HSBR, the maximum value of the loss tangent tan delta is easily adjusted to the above range because the impact absorption layer has an appropriate glass transition temperature . Further, since the butylene skeleton of SEBS has a large steric hindrance and is a structure that easily inhibits crystallization, the value of tan? Increases and the shock absorbing property tends to be exhibited. Therefore, the content of the butylene skeleton in the soft segment when the styrene-based elastomer is SEBS is not particularly limited, but is preferably 45% by weight or more. By setting the content of the butylene skeleton to 45 wt% or more, excellent impact resistance can be exhibited. The content of the butylene skeleton is more preferably 60% by weight or more, and still more preferably 70% by weight or more.

In SEPS, crystallization does not easily occur because there are no three or more ethylene skeletons continuously, and since the propylene skeleton volume is large, the value of tan? Increases and the shock absorbing property tends to be developed.

The skeleton of 1,4-butadiene that the SBBS has in the soft segment also tends to undergo crystallization easily as in the case of the ethylene skeleton, so that the flexibility may be impaired. As a result, the maximum value of tan delta decreases and the impact resistance may be lowered. Therefore, the total content of ethylene and 1,4-butadiene in the soft segment of SBBS is preferably 60% by weight or less, more preferably 50% by weight or less, and even more preferably 40% by weight or less.

Since the isobutylene skeleton contained in SIBS or the like is hardly crystallized, it is possible to control the tan? To a high level. However, since the frequency of the peak value of tan? May be out of the prescribed range, ethylene skeleton or the like is introduced into the soft segment , it is more preferable to adjust the tan? peak position.

Examples of the olefinic elastomer include polymer alloys obtained by finely dispersing an olefinic rubber (for example, EPR, EPDM) in a matrix of an olefin resin (e.g., PP, PE) Ethylene-butylene-olefin crystal (CEBC) block polymer, and styrene-ethylene-butylene-olefin crystal (SEBC) block polymer. Since the crosslinking type olefin elastomer hardly exhibits flexibility, an olefin elastomer of non-crosslinking type is preferable.

Examples of the acrylic elastomer include block copolymers of methyl methacrylate (MMA) and butyl acrylate (BA).

The content of the component derived from methyl methacrylate (MMA) in the block copolymer of methyl methacrylate (MMA) and butyl acrylate (BA) is not particularly limited, but the preferred lower limit is 1% by weight, the preferred upper limit is 50% by weight % to be. If the content of the component derived from methyl methacrylate (MMA) is less than 1% by weight, heat resistance or cohesive strength of the impact absorbing layer is lowered, and the impact resistance of the impact absorbing sheet may be lowered. If the content of the component derived from methyl methacrylate (MMA) exceeds 50% by weight, the flexibility of the block copolymer is impaired and the maximum value of the loss tangent tan δ is lowered and the impact resistance of the impact absorbing sheet is lowered . A more preferable lower limit of the content of the methyl methacrylate (MMA) -derived component is 3% by weight, and a more preferable upper limit is 30% by weight.

The block copolymer of methyl methacrylate (MMA) and butyl acrylate (BA) may be copolymerized with other polymerizable acrylic monomer copolymerizable therewith.

Examples of other copolymerizable acrylic monomer that can be copolymerized include methyl (meth) acrylate, ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-propyl (meth) acrylate, (Meth) acrylic acid alkyl ester having 13 to 18 carbon atoms in the alkyl group such as (meth) acrylic acid alkyl ester having 1 to 16 carbon atoms in the alkyl group such as isopropyl (meth) acrylate, stearyl methacrylate and stearyl (Meth) acrylate, itaconic acid, maleic anhydride, crotonic acid, maleic acid (maleic anhydride), maleic anhydride , Fumaric acid, and the like.

As a commercially available product of the acrylic elastomer, for example, Clarity LA 2330 (manufactured by Kuraray Co., Ltd.) and the like can be given.

There are two types of urethane-based elastomers, that is, an incomplete thermoplastic type having partial crosslinking in the molecule and a completely thermoplastic type that is a completely linear polymer. The incomplete thermoplastic type urethane-based elastomer is excellent in heat resistance, chemical resistance and mechanical strength.

As the urethane-based elastomer, for example, (1) a caprolactone type in which a polylactone ester polyol obtained by ring opening of caprolactone is subjected to addition polymerization of a polylactic acid in the presence of a single-chain polyol, (2) Ester type urethane type elastomer such as adipic acid type (adipate type) obtained by addition polymerization of polyisocyanate to adipic ester polyol in the presence of a single chain polyol, (3) polyurethane obtained by ring opening polymerization of tetrahydrofuran, And urethane-based elastomers of PTMG type (ether type) obtained by addition polymerization of polyisocyanate to tetramethylene glycol (PTMG) in the presence of a single chain polyol.

As a commercially available product of the ester-based urethane-based elastomer, for example, Elastollan NY585 (manufactured by BASF) can be given.

Examples of commercial products of the PTMG (ether type) urethane elastomer include Elastollan NY90A (manufactured by BASF) and Elastollan NY97A (manufactured by BASF).

The impact absorbing layer may contain a tackifying resin. By adding a tackifier resin to the impact absorbing layer, the maximum value of the loss tangent tan? Can be easily adjusted to the above range.

The tackifier resin is not particularly limited, and examples thereof include a terpene resin, a rosin resin, a petroleum resin and the like.

The impact absorbing layer may contain a softening agent in that flexibility is improved. The softening agent is not particularly limited, and examples thereof include petroleum softeners, liquid rubber softeners, dibasic acid esters, vegetable softeners, oil softeners and the like. As the petroleum softening agent, for example, Fukorflex 2050N (manufactured by Fujikosan Co., Ltd.) and Diana Process Oil PW90 (manufactured by Idemitsu Kosan Co., Ltd.) can be mentioned.

The impact-absorbing layer may contain an antioxidant or an ultraviolet absorber in that weather resistance is improved.

The antioxidant or ultraviolet absorber is not particularly limited, and examples thereof include antioxidants such as phenol, amine and benzimidazole, and ultraviolet absorbers. As the phenolic antioxidant, for example, Nocrack NS-6 (manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.) and the like can be mentioned. As the ultraviolet absorber, for example, SEESORB 101 (manufactured by Sipro Corporation) and the like can be mentioned.

The impact absorbing layer is preferably colored. By coloring the impact absorbing layer, the light of the liquid crystal display panel mounted on the portable electronic device can be shielded by the impact absorbing layer.

The colorant is not particularly limited, and pigments, dyes and the like generally incorporated in the adhesive sheet used for adhering and fixing the components constituting the portable electronic apparatus to the apparatus main body can be used. For example, Carbon black such as black, acetylene black, channel black, lamp black, and Ketjen black; Oxides such as iron oxide, titanium oxide, zinc oxide, magnesium oxide, cobalt oxide, copper oxide, chromium oxide, and alumina; Sulfates such as calcium sulfate, barium sulfate, iron sulfate and mercury sulfate; Carbonates such as calcium carbonate, magnesium carbonate, and dolomite; Metal powder such as iron powder, copper powder, tin powder, lead powder, and aluminum powder; Organic pigments such as azo pigments, phthalocyanine pigments and dioxazine pigments; Graphite and the like. Among them, carbon black is preferable.

The content of the coloring agent in the impact absorbing layer is not particularly limited. The lower limit is preferably 0.1% by weight, and the upper limit is preferably 10% by weight, more preferably 0.3% by weight and still more preferably 5% by weight. When an excessive amount of the colorant is added, coloring unevenness may occur in the impact absorbing layer due to dispersion failure of the colorant.

The impact-absorbing layer may contain fine particles for the purpose of imparting heat resistance, rigidity, conductivity, etc., or lightening it.

The fine particles are not particularly limited and may include, for example, ceramic fine particles made of silica, talc, mica, alumina or the like, metal fine particles made of copper, nickel, cobalt or gold, polyamide resin, acrylic resin, epoxy resin, Plastic fine particles made of resin, polyamideimide resin or the like, hollow fine particles made of silica or resin polymer, and the like.

The impact absorbing layer may have a foam structure for the purpose of imparting flexibility or the like. As a method of forming the above-mentioned foamed structure, for example, chemical foaming by a foaming agent, physical foaming by gas kneading, mixing hollow fine particles and the like can be mentioned.

The thickness of the impact-absorbing sheet of the present invention is not particularly limited, but is preferably 50 to 400 占 퐉. If the thickness is less than 50 占 퐉, the impact-absorbing sheet may have a reduced strength and may be broken when a strong impact is applied thereto. If the thickness exceeds 400 m, it may become difficult to meet the recent demand for thinning of the pressure-sensitive adhesive sheet.

The impact-absorbing sheet of the present invention may have another layer in addition to the above-described impact-absorbing layer if it has at least one layer of the above-mentioned impact-absorbing layer.

The other layer is not particularly limited, and for example, by laminating a resin having a high storage modulus of elasticity in the impact absorbing layer, punch workability or handleability of the impact absorbing sheet can be improved. In addition, by laminating a conductive film on the impact absorbing layer, the impact-absorbing sheet can be provided with conductivity. Further, by applying a primer to the impact-absorbing layer, adhesion between the impact-absorbing layer and a pressure-sensitive adhesive layer described later can be enhanced, or various performances can be imparted to the impact-absorbing layer. The resin constituting the other layer is not particularly limited, and examples thereof include high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polypropylene and thermoplastic elastomer.

When the impact-absorbing sheet of the present invention has another layer, the ratio of the thickness of the impact-absorbing layer to the thickness of the impact-absorbing sheet of the present invention is not particularly limited. However, A more preferred lower limit is 50%.

The method for producing the impact-absorbing sheet of the present invention is not particularly limited, and for example, a method in which a solution in which the material of the impact-absorbing layer is dissolved is applied to a release film and dried to form the impact-absorbing layer. In the case where the impact-absorbing sheet of the present invention has another layer in addition to the above-described impact-absorbing layer, for example, a method of co-extruding the material of each layer to obtain a multi-layered sheet can be given.

The use of the impact-absorbing sheet of the present invention is not particularly limited, but it is preferably used as a substrate of a pressure-sensitive adhesive sheet for adhering and fixing a component constituting a portable electronic device to an apparatus main body or a substrate of a pressure- . The portable electronic device is not limited to a conventional rigid portable electronic device, and may be a portable electronic device that is exposed to more severe conditions such as a wearable terminal and a bent double terminal.

The shape of the impact-absorbing sheet of the present invention in these applications is not particularly limited, and examples thereof include a rectangular shape, a frame shape, a circular shape, an oval shape, and a donut shape.

The impact-absorbing sheet of the present invention and the impact-absorbing adhesive sheet having at least one pressure-sensitive adhesive layer are also one of the present invention.

The impact-absorbing adhesive tape of the present invention may be a shock absorbing single-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed on one side of the impact-absorbing sheet of the present invention. It may be an adhesive sheet. In the case of a shock-absorbing double-sided pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layers on both sides may have the same composition or different compositions.

The pressure-sensitive adhesive layer preferably contains an acrylic copolymer obtained by copolymerizing a monomer mixture containing butyl acrylate and 2-ethylhexyl acrylate.

The preferred content of butyl acrylate in the total monomer mixture is 10 to 95% by weight. If the content of butyl acrylate is less than 10% by weight, the pressure-sensitive adhesive layer becomes excessively soft and the cohesive force is lowered, and the heat resistance of the impact-absorbing adhesive sheet may be lowered. If the content of butyl acrylate exceeds 95% by weight, the pressure-sensitive adhesive layer becomes hard and the adhesive strength or tack is lowered, and the impact resistance of the impact-absorbing adhesive sheet may be lowered.

The preferable content of 2-ethylhexyl acrylate in the total monomer mixture is 5 to 70% by weight. When the content of 2-ethylhexyl acrylate is less than 5% by weight, the adhesive strength of the pressure-sensitive adhesive layer is lowered and the impact resistance of the impact-absorbing adhesive sheet may be lowered. When the content of 2-ethylhexyl acrylate exceeds 70% by weight, the pressure-sensitive adhesive layer becomes excessively soft and the cohesive force is lowered, and the impact resistance of the impact-absorbing adhesive sheet may be 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 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, have.

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 acrylic copolymer preferably has a weight average molecular weight (Mw) of 400,000 to 1,500,000. If the weight average molecular weight is less than 400,000, the pressure-sensitive adhesive layer becomes excessively soft and the cohesive force is lowered, and the impact resistance of the impact-absorbing adhesive sheet may be lowered. If the weight average molecular weight exceeds 1.5 million, the adhesive strength of the pressure-sensitive adhesive layer is lowered and the impact resistance of the impact-absorbing adhesive sheet may be lowered. A more preferable lower limit of the weight average molecular weight is 500,000, and a more preferable upper limit is 1,200,000.

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 calculated by gel permeation chromatography (GPC).

The pressure-sensitive adhesive layer preferably contains a tackifier resin.

Examples of the tackifier resin include rosin ester resin, hydrogenated rosin resin, terpene resin, terpene phenol resin, coumarone indene resin, alicyclic saturated hydrocarbon resin, C5 petroleum resin, C9 petroleum resin Resin, a C5-C9 copolymer based petroleum resin, and the like. These tackifier resins may be used alone or in combination of two or more.

The content of the tackifier resin is not particularly limited, but the lower limit is preferably 10 parts by weight and the upper limit is preferably 50 parts by weight based on 100 parts by weight of the acrylic copolymer. If the content of the tackifier resin is less than 10 parts by weight, the impact resistance of the impact-absorbing adhesive sheet may decrease. If the content of the tackifier resin is more than 50 parts by weight, the pressure-sensitive adhesive layer becomes hard and adherence or tack is lowered, and the impact resistance of the impact-absorbing adhesive sheet may be lowered. A more preferable upper limit of the content of the tackifier resin is 15 parts by weight, and a more preferable upper limit is 40 parts by weight.

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

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 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the acrylic copolymer.

If the degree of crosslinking of the pressure-sensitive adhesive layer is too high or too low, the pressure-sensitive adhesive layer may be easily peeled off from the adherend due to the peeling stress caused by deformation of the adherend. More preferably 50 to 50% by weight, and particularly preferably 20 to 45% by weight.

The degree of crosslinking of the pressure-sensitive adhesive layer was measured by taking W1 (g) as a pressure-sensitive adhesive layer, immersing the pressure-sensitive adhesive layer in ethyl acetate at 23 DEG C for 24 hours, filtering the insoluble fractions with a wire mesh of 200 mesh, And the weight W2 (g) of the dried residue is measured by vacuum drying to calculate by the following equation (1).

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

The pressure-sensitive adhesive layer may contain additives such as plasticizers, emulsifiers, softening agents, fillers, pigments, dyes, and other resins such as rosin-based resins, if necessary.

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. If the thickness exceeds 150 占 퐉, the pressure-sensitive adhesive layer may have poor reworkability or re-peelability.

The total thickness of the impact-absorbing adhesive sheet of the present invention is preferably 100 to 400 mu m. If the total thickness is less than 100 占 퐉, the impact resistance of the impact-absorbing adhesive sheet may be deteriorated. If the total thickness exceeds 400 占 퐉, the impact-absorbing adhesive sheet may not be suitable for use for bonding and fixing the components constituting the portable electronic apparatus to the apparatus main body.

The compression strength of the impact-absorbing adhesive sheet of the present invention is not particularly limited, but a preferable lower limit of 25% compression strength is 10 mm, and a preferable upper limit is 2000 mm. When the 25% compressive strength is less than 10 psi, the impact-absorbing adhesive sheet as a base may seep laterally when the impact-absorbing adhesive sheet is pressed against an adherend. When the 25% compressive strength exceeds 2000 ㎪, the air between the adherend and the impact-absorbing adhesive sheet hardly escapes when the impact-absorbing adhesive sheet is stuck to the adherend, have. A more preferred lower limit of the 25% compressive strength is 30 ㎪, and a more preferred upper limit is 1000..

As a method for producing the impact-absorbing adhesive sheet 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 pressure-sensitive adhesive resin and, if necessary, a crosslinking agent, and the solution of the pressure-sensitive adhesive a is coated on the surface of the impact- To form a pressure-sensitive adhesive layer (a). Next, the releasing film is superimposed on the pressure-sensitive adhesive layer (a) so that the release-treated surface thereof is opposed to the pressure-sensitive adhesive layer (a).

Next, a release film different from the release film is prepared, a solution of the pressure-sensitive adhesive agent b is applied to the release-treated surface of the release film, and the solvent in the solution is completely dried to remove the pressure- A film is prepared. The obtained laminated film is laminated on the rear surface of the impact-absorbing sheet 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 impact- By pressing the laminate with a rubber roller or the like, a shock-absorbing adhesive sheet having a pressure-sensitive adhesive layer on both sides of the impact-absorbing sheet and a surface of the pressure-sensitive adhesive layer covered with a release film can be obtained.

In addition, two sets of laminated films were prepared in the same manner, and these laminated films were laminated on both sides of the impact-absorbing sheet as a base material, with the pressure-sensitive adhesive layer of the laminated film being opposed to the impact- Sensitive adhesive sheet in which the pressure sensitive adhesive layer is coated on both sides of the impact-absorbing sheet and the surface of the pressure-sensitive adhesive layer is covered with the release film may be obtained by pressing the laminate with a rubber roller or the like.

The use of the impact-absorbing adhesive sheet of the present invention is not particularly limited, but it is preferable that the component constituting the portable electronic device is adhesively fixed to the main body of the apparatus and the application of adhesive to the vehicle component is preferable. Specifically, the impact-absorbing adhesive sheet of the present invention can be used, for example, as a shock-absorbing adhesive sheet for adhering and fixing a liquid crystal display panel of a portable electronic device to an apparatus main body. The portable electronic device is not limited to a conventional rigid portable electronic device but may be a portable electronic device exposed to more severe conditions such as a wearable terminal and a bent double terminal.

The shape of the impact-absorbing adhesive sheet 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.

In particular, the impact-absorbing double-faced pressure-sensitive adhesive sheet of the present invention is in the form of a frame, which is a shock-absorbing double-faced pressure-sensitive adhesive sheet for fixing a front plate, a shock- It is possible to effectively prevent the portable electronic device from being damaged even when an impact such as dropping is applied. In particular, high impact resistance can be exhibited even when the adhesive sheet on the picture frame is narrowed (for example, 1.0 mm or less in width) along with the recent large screen size of the portable electronic device.

1 is a schematic view showing a structure of a front plate and a display unit of a general portable electronic device. The front face plate and the display unit 1 of the portable electronic device of Fig. 1 are composed of a bottom frame 2, a reflective film 3, a light guide plate 4, a PC mold 5, an optical film 6 The liquid crystal panel 8, the high transparency tape 9, the touch panel module 10, the high transparency tape 11, the double-sided adhesive sheet 12 for fixing the front plate, the double-sided adhesive sheet 7 for fixing the backlight unit, , And a front panel (cover panel) 13 are laminated in this order. 14 is a LED light source, 15 is a flexible printed circuit board.

Fig. 2 is a schematic view for explaining the method of using the double-faced pressure-sensitive adhesive sheet for fixing the front plate and the double-faced pressure-sensitive adhesive sheet for fixing the back plate. In FIG. 2, the components other than the front plate, the double-sided adhesive sheet for fixing the front plate, the casing frame, the double-faced adhesive sheet for fixing the back plate, and the back plate are omitted for simplification.

The double-faced pressure-sensitive adhesive sheet 12 for fixing the front plate has a role of adhesively fixing the front panel (cover panel) to the touch panel module or the display panel module. In Fig. 2, (Cover panel) 13 is fixed to the casing frame 18 by adhesive.

When the portable electronic device has a back plate, the back plate 17 is adhered and fixed to the casing frame 18 by the double-faced adhesive sheet 16 for fixing the back plate.

By using the impact-absorbing double-faced pressure-sensitive adhesive sheet of the present invention as the double-faced pressure-sensitive adhesive sheet for fixing the front plate and the double-faced pressure-sensitive adhesive sheet for fixing the back plate, a portable electronic device having excellent impact resistance can be obtained.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorbing double-faced pressure-sensitive adhesive double-coated pressure-sensitive adhesive tape for fixing a front plate for adhering and fixing a front plate in a portable electronic device, The impact-absorbing double-faced pressure-sensitive adhesive sheet is also one of the present invention.

A double-sided pressure-sensitive adhesive double-sided pressure-sensitive adhesive double-coated pressure-sensitive adhesive sheet for fixing a back plate for bonding and fixing a back plate in a portable electronic device, comprising: an impact-absorbing sheet of the present invention; and a pressure-sensitive adhesive layer formed on both surfaces of the impact- The impact-absorbing double-faced pressure-sensitive adhesive sheet is also one of the present invention.

The double-faced pressure-sensitive adhesive sheet 7 for fixing the backlight unit has a role of adhesively fixing the backlight unit to the PC mold 5 and the liquid crystal panel 8. [ 1, the reflective film 3, the light guide plate 4, the optical film 6, the LED light source 14, and the flexible printed circuit board 15 constitute a backlight unit.

Fig. 3 is a schematic view for explaining the method of using the double-faced pressure-sensitive adhesive sheet for fixing the backlight unit. In FIG. 3, configurations other than the double-faced pressure-sensitive adhesive sheet for fixing the backlight unit 7, the PC mold 5, and the backlight unit 19 are omitted for simplification.

By using the impact-absorbing double-faced pressure-sensitive adhesive sheet of the present invention as such a double-faced pressure-sensitive adhesive sheet for fixing a backlight unit, a portable electronic device having excellent impact resistance can be obtained.

An impact-absorbing double-faced pressure-sensitive adhesive double-coated pressure-sensitive adhesive tape for fixing a backlight unit for adhering and fixing a backlight unit in a portable electronic device, which comprises a shock-absorbing sheet of the present invention and a pressure-sensitive adhesive layer formed on both surfaces of the impact- The impact-absorbing double-faced pressure-sensitive adhesive sheet is also one of the present invention.

According to the present invention, it is possible to provide an impact-absorbing sheet having excellent impact resistance, which is preferably used as a base material of a pressure-sensitive adhesive sheet to which components constituting a portable electronic device are adhesively fixed to an apparatus main body. According to the present invention, there is provided an impact-absorbing adhesive sheet having the impact-absorbing sheet, a shock-absorbing double-faced adhesive sheet for fixing the front plate, a shock-absorbing double-faced adhesive sheet for fixing the back plate, and a shock- can do.

1 is a schematic view showing a structure of a front panel and a display unit of a general portable electronic device.
2 is a schematic view for explaining a method of using a double-faced pressure-sensitive adhesive sheet for fixing the front plate and a double-faced pressure-sensitive adhesive sheet for fixing the back plate.
3 is a schematic view for explaining a method of using the double-faced pressure-sensitive adhesive sheet for fixing the backlight unit.
Fig. 4 is a schematic diagram showing a drop impact test of the impact-absorbing adhesive sheet. Fig.

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

(Preparation of pressure-sensitive adhesive A)

79.9 parts by weight of butyl acrylate, 5 parts by weight of ethyl acrylate, 12 parts by weight of 2-ethylhexyl acrylate, 3 parts by weight of acrylic acid, and 0.1 part by weight of 2-hydroxyethyl acrylate were added to a reactor equipped with a stirrer, , And 82 parts by weight of ethyl acetate were added, and after nitrogen replacement, the reactor was heated to initiate reflux. Subsequently, 0.15 part by weight of azobisisobutyronitrile as a polymerization initiator was added to the reactor. And refluxed at 77 DEG C for 5 hours to obtain a solution of the acrylic copolymer (a). The weight average molecular weight of the obtained acrylic copolymer (a) was measured by a GPC method using " 2690 Separations Model " manufactured by Water Corporation, and found to be 650,000.

10 parts by weight of polymerized rosin ester, 16 parts by weight of terpene phenol, 10 parts by weight of hydrogenated rosin ester, and 100 parts by weight of ethyl acetate (a) were added to 100 parts by weight of the solid content of the acrylic copolymer (a) contained in the solution of the acrylic copolymer , 6.2 parts by weight of an isocyanate-based crosslinking agent ("Coronate L45" available from Nippon Polyurethane Industry Co., Ltd.) was further added to 100 parts by weight of the solid content of the acrylic polymer (a) and stirred to obtain a pressure-sensitive adhesive A.

(Example 1)

(1) Production of impact-absorbing sheet

150 g of a styrene-ethylene-butylene-styrene (SEBS) block copolymer (DYNARON "8905P" manufactured by JSR Corporation) was placed in a beaker containing 250 g of toluene and sufficiently dissolved by stirring for 1 hour. The solution was applied to a mold releasing PET film having a thickness of 75 탆 which had been subjected to silicone mold releasing treatment using an applicator and the solvent was dried at 110 캜 for 4 minutes to form a non-foamed impact absorbing layer having a thickness of 150 탆, .

The shock absorbing sheet was cut into a width of 5 mm x 30 mm and the long side of 30 mm was chucked at a chuck spacing of 15 mm in a dynamic viscoelasticity measuring apparatus (Rheogel-E4000 manufactured by UB-EM) To measure a tensile modulus of elasticity in a range of -60 ° C to 100 ° C and to synthesize a master curve at a reference temperature of 23 ° C to obtain a maximum loss tangent tan δ at a frequency of 1.0 × 10 ⁴ to 1.0 × 10 ^6.5 Hz at 23 ° C As a result of calculation, the value was 1.4. The frequency at which the loss tangent tan? Takes the maximum value was 1.0 x 10 ^4.17 Hz.

(2) Production of double-sided pressure-sensitive adhesive sheet

A pressure-sensitive adhesive (A) was applied to a release PET film having a thickness of 75 占 퐉 on which silicone release treatment had been performed using an applicator and dried at 110 占 폚 for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 50 占 퐉. The pressure-sensitive adhesive layer was bonded to the impact-absorbing sheet obtained above using a silicone roller to obtain a single-sided pressure-sensitive adhesive sheet. The impact-absorbing sheet was subjected to corona treatment on both sides under the conditions of 270 W and 18 m / min using a corona treatment apparatus ("CT-0212" manufactured by Kasuga Electric Co., Ltd.).

The release PET film on the opposite surface of the impact-absorbing sheet was peeled off in the same manner, and the same pressure-sensitive adhesive layer as above was bonded. Curing was then carried out at 40 占 폚 for 48 hours. As a result, a double-sided pressure-sensitive adhesive sheet having a total thickness of 250 占 퐉 was obtained in which both surfaces were covered with a release PET film.

(Examples 2 to 12)

As in Example 1 except that the material of the impact absorbing layer, the thickness of the impact absorbing layer, the maximum value of the loss tangent tan? Of the impact absorbing layer, and the thickness of the pressure sensitive adhesive layer were changed as shown in Tables 5 and 6, To obtain a pressure-sensitive adhesive sheet.

In addition, the material of the impact absorbing layer shown below was used.

SEBS block copolymer (Tuftec " H1221 " manufactured by Asahi Chemical Industry Co., Ltd.)

SEBS block copolymer (Dynalon " 8600P " manufactured by JSR Corporation)

SEBS block copolymer (Dynalon " 8300P " manufactured by JSR Corporation)

SEBS block copolymer (Dynalon " 8906P " manufactured by JSR Corporation)

SEBS block copolymer (Tuftec " H1062 " manufactured by Asahi Chemical Industry Co., Ltd.)

HSBR block copolymer (Dynalon " 1320P " manufactured by JSR Corporation)

SEPS block copolymer (Ceftone " 2063 " manufactured by Kuraray Co., Ltd.)

SIBS block copolymer (Seabstar " 062UM " manufactured by Kaneka Corporation)

· Acrylic elastomer (Clarie "2330" manufactured by Kuraray Co., Ltd.)

· Acrylic elastomer (Clarity "2140e" manufactured by Kuraray Co., Ltd.)

(Example 13)

Sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the material of the impact absorbing layer, the thickness of the impact absorbing layer, the maximum value of the loss tangent tan? Of the impact absorbing layer and the thickness of the pressure-sensitive adhesive layer were changed as shown in Table 6 .

Further, instead of forming a shock absorbing layer by applying a solution obtained by dissolving the material of the impact absorbing layer to the release film and drying the same, the following sheet material was obtained and used in the impact absorbing layer.

· Urethane elastomer ("DUS614" manufactured by Cydam Company)

(Example 14)

Sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the material of the impact absorbing layer, the thickness of the impact absorbing layer, the maximum value of the loss tangent tan? Of the impact absorbing layer and the thickness of the pressure-sensitive adhesive layer were changed as shown in Table 6 .

Further, instead of applying the solution obtained by dissolving the material of the impact absorbing layer to the release film and drying the same to form an impact absorbing layer, polyethylene (PE) (Sumitomo Chemical Co., Ltd.) was coated on both sides of SEBS block copolymer (DYNARON 8600, ("Sumikasen F218-0" manufactured by Kagaku Kogyo Co., Ltd.) was co-extruded to obtain a three-layer structure sheet (thickness: 150 μm). The ratio of the thickness of each layer on the cross section of the three-layer structure sheet was measured using VHX-500 (manufactured by KYENS). As a result, PE: SEBS (Dynalon "8600"): PE = 20: 110:

(Comparative Examples 1 to 4)

Sensitive adhesive sheet in the same manner as in Example 1 except that the material of the impact-absorbing layer, the thickness of the impact-absorbing layer, the maximum value of the loss tangent tan? Of the impact-absorbing layer, and the thickness of the pressure- .

Further, instead of forming a shock absorbing layer by applying a solution obtained by dissolving the material of the impact absorbing layer to the release film and drying the same, the following sheet material was obtained and used in the impact absorbing layer.

· Urethane elastomer ("DUS213" manufactured by Cydam Company)

· Urethane elastomer ("DUS203" manufactured by Cydam Company)

· PE foam (polyolefin foam "XLH-05002" manufactured by Sekisui Chemical Co., Ltd.)

PET film (Lou mirror " S10 " manufactured by Torrance)

(Comparative Examples 5 to 8)

Sensitive adhesive sheet in the same manner as in Example 1 except that the material of the impact-absorbing layer, the thickness of the impact-absorbing layer, the maximum value of the loss tangent tan? Of the impact-absorbing layer, and the thickness of the pressure- .

In addition, the material of the impact absorbing layer shown below was used.

SEBS block copolymer (Tuftec " H1041 " manufactured by Asahi Chemical Industry Co., Ltd.)

SBBS block copolymer (Tuftec " P1083 " manufactured by Asahi Chemical Industry Co., Ltd.)

SBBS block copolymer (Tuftec " P2000 " manufactured by Asahi Chemical Industry Co., Ltd.)

· Acrylic elastomer (Clarity "2250" manufactured by Kuraray Co., Ltd.)

(Comparative Example 9)

Sensitive adhesive sheet in the same manner as in Example 1 except that the material of the impact-absorbing layer, the thickness of the impact-absorbing layer, the maximum value of the loss tangent tan? Of the impact-absorbing layer, and the thickness of the pressure- .

Further, an impact-absorbing layer was formed as follows.

13.5 parts by weight of a polymerized rosin ester ("D-160" manufactured by Arakawa Chemical Industries, Ltd.), 100 parts by weight of terpene phenol (produced by Yasuhara Chemical Co., Ltd., 13.5 parts by weight of a hydrogenated rosin ester ("Ester Gum H" manufactured by Arakawa Chemical Industries, Ltd.), 18 parts by weight of an acrylic copolymer (G-150), 100 parts by weight of a solid component of an acrylic polymer 7.9 parts by weight (trade name, "Colonate L45" manufactured by Nippon Shokubai Co., Ltd.) was added, and the solution obtained by stirring was applied to a 75 μm thick release PET film C for 4 minutes, and then cured at 40 DEG C for 48 hours to obtain an acrylic pressure sensitive adhesive sheet as an impact absorbing layer having a thickness of 200 mu m.

≪ Composition of material of impact absorbing layer >

("ADVANCE 400" manufactured by Bruker BioSpin Co., Ltd.) was used for the styrene-ethylene-butylene-styrene (SEBS) block copolymer among the materials of the shock absorbing layer used in Examples and Comparative Examples , ¹ H-NMR (1H-nuclear magnetic resonance) measurement using deuterated chloroform as a solvent, and styrene, ethylene, and butylene content measured by ¹³ C-NMR are shown in Table 1. In Table 1, the number in parentheses is the ratio of each component in 100 parts by weight of the soft segment.

("ADVANCE400" manufactured by Bruker Spin Co., Ltd.) was used for the styrene-ethylene-propylene-styrene (SEPS) block copolymer as a material of the shock absorbing layer used in Examples and Comparative Examples, The content of styrene, ethylene and propylene measured by ¹ H-NMR (1H-nuclear magnetic resonance) measurement using deuterated chloroform and by ¹³ C-NMR is shown in Table 2. The numbers in parentheses in Table 2 are the ratio of each component in 100 parts by weight of the soft segment.

A nuclear magnetic resonance apparatus ("ADVANCE 400" manufactured by Bruker Spin Co., Ltd.) was used for the styrene-butadiene-butylene-styrene (SBBS) block copolymer in the material of the shock absorbing layer used in the comparative example, Table 1 shows the content of styrene, ethylene, 1,4-butadiene, and butylene measured by ¹ H-NMR (1H-nuclear magnetic resonance) measurement using deuterated chloroform and ¹³ C-NMR. In Table 3, the number in parentheses is the ratio of each component in 100 parts by weight of the soft segment.

("ADVANCE 400" manufactured by Bruker Spin Co., Ltd.) was used for the styrene-isobutylene-styrene (SIBS) block copolymer among the materials of the shock absorbing layer used in the examples, Table 1 shows the content of styrene and isobutylene measured by ¹ H-NMR (1H-nuclear magnetic resonance) measurement using chloroform and by ¹³ C-NMR.

<Evaluation>

The double-sided pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were subjected to the following evaluations. The evaluation results are shown in Tables 5-7.

(1) Drop impact test

&Lt; Preparation of test apparatus &gt;

Fig. 4 is a schematic view of a drop impact test of the double-sided pressure-sensitive adhesive sheet (impact-absorbing adhesive sheet) obtained in Examples and Comparative Examples. The obtained double-sided pressure-sensitive adhesive sheet was extruded at 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. 4 (a), a test piece 41 having a release sheet peeled off to a polycarbonate plate 43 having a thickness of 2 mm and a square width of 38 mm and a length of 50 mm was formed in the central portion thereof, The polycarbonate plate 42 having a width of 55 mm, a length of 65 mm and a thickness of 1 mm was pasted from the upper surface of the test piece 41 so that the test piece 41 was positioned substantially at the center of the test piece 41 , And the test apparatus was assembled.

Thereafter, a pressure of 5 kgf was applied from the side of the polycarbonate plate located on the upper side of the test apparatus for 10 seconds, and the polycarbonate plate and the test piece were pressed and placed at room temperature for 24 hours.

&Lt; Determination of drop impact resistance &

As shown in Fig. 4 (b), the fabricated test apparatus was turned upside down and fixed to a support, and iron balls 44 having a weight of 300 g sized to pass through the square holes were dropped to pass through the square holes. The height at which the steel ball was dropped was gradually raised, and the height at which the steel ball was dropped when the test piece and the polycarbonate plate were peeled off due to impact applied by dropping the steel ball was measured. A judgment was made when the result was 120 cm or more, a case where the result was 80 cm or more and less than 120 cm, and a case where the result was less than 80 cm.

(2) Measurement of 25% compressive strength

The obtained double-sided pressure-sensitive adhesive sheet was cut into 15 mm x 15 mm and superimposed until it became about 5 mm to obtain a laminate sample. After the thickness of the laminate sample was measured, it was sandwiched between 1 mm thick PC plates and compressed at a speed of 10 mm / min by "Autograph AGS-X" manufactured by Shimadzu Corporation. The stress at the time of compression of 25% of the original thickness was obtained, and the compressive strength was calculated by dividing by the area.

Industrial availability

According to the present invention, it is possible to provide an impact-absorbing sheet having excellent impact resistance, which is preferably used as a base material of a pressure-sensitive adhesive sheet to which components constituting a portable electronic device are adhesively fixed to an apparatus main body. According to the present invention, there is provided an impact-absorbing adhesive sheet having the impact-absorbing sheet, a shock-absorbing double-faced adhesive sheet for fixing the front plate, a shock-absorbing double-faced adhesive sheet for fixing the back plate, and a shock- can do.

1: Front panel and display unit of portable electronic device
2: Bottom frame
3: Reflective film
4: Light guide plate
5: PC mold
6: Optical film
7: Double-sided adhesive sheet for backlight unit fixing
8: liquid crystal panel
9: Highly transparent tape
10: Touch panel module
11: Opaque tape
12: Double-sided adhesive sheet for fixing the front plate
13: Front panel (cover panel)
14: LED light source
15: Flexible printed circuit board
16: Double-sided pressure-sensitive adhesive sheet for fixing the back plate
17: back plate
18: casing frame
19: Backlight unit
41: Specimen (on frame)
42: Polycarbonate plate (thickness: 1 mm)
43: Polycarbonate plate (thickness: 2 mm)
44: Iron (300 g)

Claims (10)

Wherein the maximum value of the loss tangent tan delta at a frequency of 1.0 x 10 ⁴ to 1.0 x 10 ^6.5 Hz at 23 캜 is 0.84 or more. The method according to claim 1,
Wherein the maximum value of the loss tangent tan? At a frequency of 1.0 x 10 ⁴ to 1.0 x 10 ^6.5 Hz at 23 占 폚 is 1.31 or more. 3. The method according to claim 1 or 2,
Wherein the impact absorbing layer contains an elastomer. The method of claim 3,
Wherein the elastomer is a styrene elastomer, an olefin elastomer, an acrylic elastomer, or a urethane elastomer. The method according to any one of claims 1, 2, 3, and 4,
And a thickness of 50 to 400 占 퐉. The method according to any one of claims 1, 2, 3, 4, and 5,
Characterized in that the impact-absorbing sheet is used as a base material of a pressure-sensitive adhesive sheet for adhering and fixing a component constituting a portable electronic device to an apparatus main body. A pressure-sensitive adhesive sheet, comprising the impact-absorbing sheet according to any one of claims 1, 2, 3, 4, 5, and 6 and at least one pressure- . BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive double-sided pressure-sensitive adhesive double-coated pressure-sensitive adhesive tape for fixing a front plate for adhering and fixing a front plate in a portable electronic device,
A pressure-sensitive adhesive sheet comprising the impact-absorbing sheet according to any one of claims 1, 2, 3, 4, 5 and 6, and a pressure-sensitive adhesive layer formed on both sides of the impact- Impact-absorbing double-sided adhesive sheet for fixing the front plate. An impact-absorbing double-faced pressure-sensitive adhesive double-coated pressure-sensitive adhesive tape for fixing a back plate for adhering and fixing a back plate in a portable electronic device,
A pressure-sensitive adhesive sheet comprising the impact-absorbing sheet according to any one of claims 1, 2, 3, 4, 5 and 6, and a pressure-sensitive adhesive layer formed on both sides of the impact- Impact - absorbing double - sided adhesive sheet for back plate fixing. A double-sided pressure-sensitive adhesive double-coated pressure-sensitive adhesive tape for fixing a backlight unit for fixing a backlight unit in a portable electronic device,
A pressure-sensitive adhesive sheet comprising the impact-absorbing sheet according to any one of claims 1, 2, 3, 4, 5 and 6, and a pressure-sensitive adhesive layer formed on both sides of the impact- Impact-absorbing double-sided adhesive sheet for fixing backlight unit.

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