JP2016000822A - Double-sided adhesive tape for waterproofing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double-sided adhesive tape for waterproofing, waterproofness of which is not deteriorated even when its width is reduced.SOLUTION: The double-sided adhesive tape for waterproofing comprises: a substrate 3 formed of a non-foamed elastomer; and adhesive layers 2 comprising an adhesive which are placed on both of front and back surfaces of the substrate 3. The substrate 3 has a thickness of 50 μm or more and 1000 μm or less, and the substrate 3 satisfies at least one condition of the following two: that a Young's modulus determined from a load-displacement curve when an indenter is indented by a nanoindentation method is in a range of 5 to 500 MPa; and that an indentation depth when an indenter is indented by a nanoindentation method is in a range of 4 to 15 μm.

Description

  The present invention relates to a waterproof double-sided pressure-sensitive adhesive tape.

  The double-sided pressure-sensitive adhesive tape can be easily processed into an arbitrary shape by punching before being attached to an adherend, and is used for fixing parts in various industrial fields. For example, nameplates and display parts of electronic devices such as mobile phone terminals and digital cameras are becoming smaller and more complicated with the downsizing of electronic devices, so double-sided adhesive tape is used for joining them. Yes.

  Here, as an example, a double-sided adhesive tape used in a mobile phone terminal will be described with reference to FIG. In a mobile phone terminal, a liquid crystal display element is mounted inside the casing of the mobile phone terminal, and a surface plate made of a transparent material such as acrylic resin or glass is attached to the casing so as to cover the liquid crystal display element. . At this time, the surface plate is fixed to the housing by a double-sided adhesive tape formed in a frame shape.

  The double-sided pressure-sensitive adhesive tape has functions of waterproofing, impact resistance and shock absorption in addition to fixing the surface plate and the housing. In other words, water is prevented from entering the inside of the mobile phone terminal from between the face plate and the case, and the impact force applied to the face plate is absorbed without damaging the tape. This prevents damage to the surface plate. Since the double-sided adhesive tape that fixes the housing and the surface plate of the mobile phone terminal is required to have the above-described functions, conventionally, as disclosed in Patent Documents 1 to 3, foaming of resin is required. A double-sided pressure-sensitive adhesive tape based on the body has been used.

JP 2010-155969 A JP 2009-108314 A JP 2009-084367 A

  Since the liquid crystal screen of the mobile phone terminal is getting larger year by year, the width of the double-sided adhesive tape formed in a frame shape is narrowed accordingly (see FIG. 6). In recent years, it has been required to narrow the width to 1 mm or even less than 1 mm. However, since the resin foam constituting the base material of the double-sided pressure-sensitive adhesive tape cannot sufficiently guarantee that the maximum diameter of the bubbles is less than 0.5 mm, the waterproofness of the double-sided pressure-sensitive adhesive tape may be impaired by the narrowing of the width. was there.

 That is, as can be seen from FIG. 7 showing an enlarged portion A surrounded by a circle in FIG. 6, when there is a bubble having a diameter of 0.5 mm or more, two bubbles are connected. There was a possibility that a through-hole penetrating the double-sided pressure-sensitive adhesive tape having a width of 1 mm in the width direction was formed by the two connected bubbles. If the through-hole is formed, water may enter the inside of the mobile phone terminal through the through-hole, resulting in a decrease in waterproofness.

 Therefore, in order to guarantee the waterproofness by the double-sided pressure-sensitive adhesive tape, the width of the double-sided pressure-sensitive adhesive tape needs to be larger than twice the diameter of the foam bubbles. There is currently no foam substrate that is 100% guaranteed that the maximum bubble diameter is less than 0.5 mm and that all the bubbles formed are closed cells in the lot-quality variation. Therefore, as long as the foam is used as the base material, it has not been possible to sufficiently meet the demand for narrowing the width to 1 mm and even less than 1 mm. Under these circumstances, there has been a problem in increasing the size of the liquid crystal screen of the mobile phone terminal.

  Accordingly, the present invention solves the problems of the prior art as described above, and waterproof waterproof double-sided adhesive tape that does not deteriorate waterproofing even when it is narrowed and has excellent impact resistance and shock absorption. It is an issue to provide.

In order to solve the above-mentioned problems, the present inventors have intensively studied a base material other than a foam that can achieve both waterproofness, impact resistance, and shock absorption even when the width is narrowed. It was. The present invention has the following configuration. That is, aspects of the present invention comprises a substrate made of a non-foam et elastomer, and a pressure-sensitive adhesive layer disposed on both sides of and the base material consists of an adhesive, the substrate thickness is 50μm The double-sided adhesive tape for waterproofing having a thickness of 1000 μm or less, wherein the base material has a Young's modulus in a range of 5 to 500 MPa determined from a load-displacement curve when an indenter is pushed by a nanoindentation method, and a nanoindentation The indentation depth when the indenter is pushed in by the method satisfies the condition of at least one of the range of 4 to 15 μm .

In the above aspect, the base material is at least one selected from ethylene propylene rubber (EPDM), urethane rubber, and ethylene-vinyl acetate copolymer (EVA).

 In the above aspect, the substrate has a three-layer structure including a pair of outer layers and an inner layer sandwiched between the outer layers.

  In the above aspect, the base material is mainly composed of an ethylene / vinyl acetate copolymer, the VA% of the outer layer is 1 to 10%, and the VA% of the inner layer is 1 to 40%. And

  As said aspect, ratio of the thickness dimension of the outer side layer of a base material and an inner side layer, the thickness dimension of an outer side layer: the thickness dimension of an inner side layer is 1: 4-4: 1, It is characterized by the above-mentioned.

  As the above aspect, the waterproof double-sided pressure-sensitive adhesive tape is used for a portable device.

  As the above aspect, the waterproof double-sided pressure-sensitive adhesive tape is used for an outdoor installation type display device.

  As said aspect, the use width dimension of the waterproofing double-sided adhesive tape is 0.8-5.0 mm, It is characterized by the above-mentioned.

  ADVANTAGE OF THE INVENTION According to this invention, even if it narrows, waterproofness does not fall, and the double-sided adhesive tape for waterproofing excellent in impact resistance and shock absorption property is realizable.

FIG. 1 is a cross-sectional view illustrating the structure of one embodiment of a waterproof double-sided pressure-sensitive adhesive tape according to the present invention. FIG. 2 is a cross-sectional view illustrating the structure of a modified example of the waterproof double-sided pressure-sensitive adhesive tape of FIG. FIG. 3 is a cross-sectional view when the substrate has a three-layer structure. FIG. 4 shows a load-displacement curve of an elastic / plastically deformable substance, and is a diagram showing a concept of load and indenter displacement indicating specifications used for calculation including contact depth. FIG. 5 is an exploded perspective view of a main part of the mobile phone terminal. FIG. 6 is a schematic view for explaining the narrowing of the double-sided pressure-sensitive adhesive tape formed in a frame shape. FIG. 7 is an enlarged view of a portion A in FIG. It is a schematic diagram of the measurement data of an impact absorptivity test.

  An embodiment of a waterproof double-sided pressure-sensitive adhesive tape according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view (cross-sectional view cut along a plane perpendicular to the longitudinal direction of the waterproof double-sided pressure-sensitive adhesive tape) for explaining the structure of one embodiment of the waterproof double-sided pressure-sensitive adhesive tape according to the present invention.

  In the waterproof double-sided pressure-sensitive adhesive tape of the present embodiment, the substrate 3 is composed of an elastomer non-foamed material. The substrate 3 may be subjected to surface treatment such as corona treatment or plasma treatment, or may be applied with an anchor coating agent. And the adhesion layers 2 and 4 which consist of an adhesive are provided in the front and back both surfaces of this base material 3. As shown in FIG. Further, release liners 1 and 5 are laminated on the adhesive layers 2 and 4, respectively. In the waterproof double-sided pressure-sensitive adhesive tape of this embodiment, release liners 1 and 5 having a release treatment applied on one side are laminated on the front and back surfaces as shown in FIG. Moreover, the release liner 6 that has been subjected to the release treatment on both sides may be laminated only on one side.

  Since the base material 3 of the waterproof double-sided pressure-sensitive adhesive tape of the present embodiment is composed of an elastomer non-foamed body, it does not include bubbles. Therefore, even if the waterproof double-sided pressure-sensitive adhesive tape is narrowed to, for example, 1 mm or less, there is no possibility that a through-hole penetrating the waterproof double-sided pressure-sensitive adhesive tape in the width direction is formed by air bubbles. There is no decline in sex. Moreover, since the base material 3 is comprised with the elastomer, it is excellent in impact resistance and impact absorption.

  Because of such excellent performance, the waterproof double-sided pressure-sensitive adhesive tape of this embodiment can be used for fixing parts in various industrial fields, and is particularly required to be waterproof like electronic devices. Suitable for fixing parts in equipment. For example, portable devices and outdoor display devices are required to be waterproof because they are likely to come into contact with water such as rainwater, but if the waterproof double-sided adhesive tape of this embodiment is used to fix the parts, Such a device can be provided with excellent waterproofness.

  The type of portable device is not particularly limited as long as it is an electronic device that is usually carried and carried, but examples thereof include portable communication terminals such as mobile phone terminals, digital cameras, and video cameras. Portable recording devices such as portable recording devices, portable music players, portable televisions, notebook personal computers, portable game machines, electronic dictionaries and the like.

  Here, an example in which the waterproof double-sided pressure-sensitive adhesive tape of this embodiment is used for fixing components in a mobile phone terminal will be described with reference to FIG.

  First, a waterproof double-sided adhesive tape is punched out with a mold to form a frame as shown in FIG. At this time, the width of the waterproof double-sided pressure-sensitive adhesive tape is set to 1 mm. Using the waterproof double-sided adhesive tape formed in this frame shape, as shown in FIG. 5, the surface plate is fixed to the casing of the mobile phone terminal.

  This waterproof double-sided pressure-sensitive adhesive tape is excellent in waterproofness because the base material 3 is made of an elastomer non-foamed material and does not have bubbles. Therefore, water can be prevented from entering the mobile phone terminal from between the surface plate and the housing. As described above, when the waterproof double-sided pressure-sensitive adhesive tape of the present embodiment is used, the waterproof property does not deteriorate even if the width of the waterproof double-sided pressure-sensitive adhesive tape used for fixing is narrowed. It contributes to the enlargement of the liquid crystal screen of the cellular phone terminal by widening. Further, the waterproof double-sided pressure-sensitive adhesive tape of this embodiment also has functions of impact resistance and shock absorption since the base material 3 is made of an elastomer. That is, it is effective in resisting the impact force applied to the surface plate and absorbing the impact force to prevent damage to the surface plate and the like.

  Here, the waterproof double-sided pressure-sensitive adhesive tape of this embodiment will be described in more detail. First, the base material 3 will be described.

  The base material 3 is a sheet made of an elastomer. The type of elastomer is not particularly limited, and examples thereof include thermosetting elastomers such as vulcanized rubber and thermosetting resin elastomers, and thermoplastic elastomers. Specifically, silicone rubber, urethane rubber, butyl rubber, ethylene propylene rubber (EPDM), nitrile rubber (NBR), block copolymer of styrene and butadiene (SBR), fluoro rubber, ethylene-vinyl acetate copolymer (EVA) elastomer Polyolefin ionomers, metallocene-catalyzed polymerized polyolefins, polyolefins in which ethylene propylene rubber (EPDM) is finely dispersed are preferred, and among these, EPDM and EVA elastomers are more preferred. One type of these elastomers may be used alone, two or more types of elastomers may be used, or a single type or a laminate of two or more types of elastomers may be used. In addition, if it is an elastic material, it is also possible to use the sheet | seat which consists of a non-foamed material other than an elastomer as the base material 3.

  When the base material 3 is a laminate, a three-layer structure is preferable, and a soft material is used for the inner layer, and it is preferable to use a material that does not cause blocking even when the base material alone is rolled into both outer layers. For example, the VA% is not particularly limited, but an ethylene-vinyl acetate copolymer having a VA% of 20% is used for the inner layer, and an ethylene-vinyl acetate copolymer having a VA% of 5% is formed on both outer sides thereof. Polymer laminated, metallocene-catalyzed polymerized polyolefin in the inner layer, polyethylene (PE) laminated on both outer sides, polyolefin ionomer on the inner layer, polyethylene (PE) laminated on both outer sides are preferred Of these, an ethylene-vinyl acetate copolymer having a VA% of 20% is used for the inner layer, and an ethylene-vinyl acetate copolymer having a VA% of 5% is laminated on both outer sides thereof.

  Although the thickness of the base material 3 is not specifically limited, When fixing a surface board to the housing | casing of a mobile telephone terminal, 50 micrometers or more and 1000 micrometers or less are preferable. Further, as shown in FIG. 3, the base material 3 may be composed of an inner layer 3A and outer layers 3B and 3C sandwiching the inner layer 3A.

  Moreover, when the elastomer is defined by a Young's modulus obtained from a load-displacement curve when the indenter is pushed into the elastomer by the nanoindentation method, it is effective that the Young's modulus is 5 to 500 MPa. Further, when the elastomer is defined by the indentation depth obtained from the load-displacement curve when the indenter is pushed into the elastomer by the nanoindentation method, it is effective that the indentation depth is 4 to 15 μm. The elastomer of the present embodiment has a Young's modulus obtained from a load-displacement curve when the indenter is pushed by the nanoindentation method in a range of 5 to 500 MPa, and a push depth of 4 to 15 μm. An elastomer that satisfies at least one of the conditions may be used, and an elastomer that satisfies both the conditions may be used.

The measuring method of Young's modulus and indentation depth in the present invention is shown below.
(1) Measuring instrument: Elionix Co., Ltd. ultra-indentation hardness tester ENT-1100a was used, and a triangular pyramid indenter (Berkovic indenter) ridge angle of 115 ° was used as the indenter.
(2) Measurement conditions: A sample cut into a 5 mm square was attached to a slide glass with water so that air did not enter, thereby preparing a measurement sample. The sample was loaded with 20 mgf at 100 msec intervals with an indenter until a load of 1000 mgf was applied. This state was maintained for 1000 msec, and then the load was removed in the same manner.
(3) Calculation of Young's modulus and indentation depth:
For the indentation depth, the amount of indentation when the maximum load was reached was measured.
(3) Calculation of Young's modulus and indentation depth:
For the indentation depth, the amount of indentation when the maximum load was reached was measured.
The Young's modulus Es was calculated by the following formula.

As shown in FIG. 4, the maximum displacement point at the maximum load Pmax is hmax, the unloading curve from hmax is a quadratic approximate curve up to 50%, the tangent to hmax is extended, and the X coordinate intersecting the horizontal axis is h1, Let hmax-h1 be h2.
S = dP / dh = C _A Ar ^1/2 E *
S: Contact rigidity dP / dh = Pmax / h2
C _A : contact constant C _A = 2 / π ^1/2 ≈1.13
A _r : contact projection area Ar = 3 ^3/2 tan ² αh1 ² (α = 65 °)
E *: Composite elastic modulus ∴ E * = 181.029 × 10 ⁻³ × Pmax / (h1 × h2) [mgf / μm ² ]
1 / E * = (1−ν _i ² ) / E _i + (1−ν _s ² ) / E _s
E _s = (1−ν _s ² ) / {1 / E * − (1−ν _i ² ) / E _i
E _s : Elastic modulus of the sample (Young's modulus)
E _i : Elastic modulus of indenter (E _i = 1050 GPa)
ν _s : Poisson's ratio of the sample (JIS
Measured based on K 7161 / ISO 5271. )
ν _i : Poisson's ratio of the indenter (ν _i = 0.1)

  Furthermore, when rubber is used as the elastomer, both vulcanized rubber and unvulcanized rubber can be used without any problem, and may be appropriately selected depending on the purpose, application, and the like. However, in consideration of environmental resistance (light resistance, etc.) and creep performance, vulcanized rubber is preferred.

  The elastomer may be colorless or colored such as black or white. Further, it may be transparent (light transmissive) or opaque (light non-transmissive). The method for coloring the elastomer is not particularly limited, but a coating film may be provided on the surface of the elastomer sheet by a printing method, or a colorant, a pigment, a dye or the like may be mixed with the elastomer itself. Good.

  Moreover, you may mix an additive with an elastomer as needed. For example, an antioxidant may be mixed.

  The surface of the elastomer sheet is preferably smooth, but a large number of fine irregularities may be provided depending on the purpose and application.

  Next, the adhesive which comprises the adhesion layers 2 and 4 is demonstrated. The type of pressure-sensitive adhesive constituting the pressure-sensitive adhesive layers 2 and 4 is not particularly limited, and examples thereof include acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, ether-based pressure-sensitive adhesives, and rubber-based pressure-sensitive adhesives. It is done. A hot melt type adhesive may be used. However, in view of heat resistance, environmental resistance, and cost, acrylic adhesives are more preferable, and ethyl acrylate (EA), butyl acrylate (BA), 2-ethylhexyl acrylate (2-EHA), etc. are the main components. An acrylic adhesive is more preferable. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 2 and the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 4 may be the same or different.

  The thickness of the adhesive layers 2 and 4 is not particularly limited, but is preferably 2 μm or more and 200 μm or less. In addition, the thickness of the adhesion layer 2 and the thickness of the adhesion layer 4 may be the same, and may differ.

  Furthermore, the pressure-sensitive adhesive can be used without any problem, either a crosslinked type or an uncrosslinked type, and may be appropriately selected depending on the purpose, application and the like. However, in consideration of environment resistance (light resistance, etc.) and creep performance, a cross-linked type is preferred.

  Furthermore, the pressure-sensitive adhesive may be colorless or colored. Further, it may be transparent (light transmissive) or opaque (light non-transmissive). The method for coloring the pressure-sensitive adhesive is not particularly limited, but a colorant, a pigment, a dye or the like may be mixed in the pressure-sensitive adhesive. Furthermore, you may mix an additive with an adhesive if desired. For example, an antioxidant may be mixed.

  Next, the release liners 1, 5, and 6 will be described. The material of the release liners 1, 5, and 6 is not particularly limited, but paper or a resin film can be used. The release liners 1, 5 and 6 are subjected to a release treatment on one side or both sides. In the case of the waterproof double-sided pressure-sensitive adhesive tape in FIG. 2, the release treatment is performed on both surfaces of the release liner 6.

  The length of the waterproof double-sided pressure-sensitive adhesive tape is not particularly limited, and may be a strip-like long article or a short-length article (sheet-like article) having a length and shape depending on the application.

  Next, a method for producing a waterproof double-sided pressure-sensitive adhesive tape will be described by taking the waterproof double-sided pressure-sensitive adhesive tape of FIG. 1 as an example. First, for example, an acrylic pressure-sensitive adhesive is applied to the release treatment surface of the release liner 1 and dried to form the pressure-sensitive adhesive layer 2. The coating method is not particularly limited, and known methods such as a dip coating method, a roll coating method, a curtain coating method, a die coating method, and a slit coating method can be adopted without any problem. Then, a base material 3 made of, for example, an EPDM rubber sheet or an EVA sheet is laminated on the adhesive layer 2 to form a three-layer structure. On the other hand, for example, an acrylic pressure-sensitive adhesive is applied to the release-treated surface of the release liner 5 and dried to form the pressure-sensitive adhesive layer 4. And said 3 layer structure is laminated | stacked on the adhesion layer 4 so that the base material 3 and the adhesion layer 4 may contact | connect, and it is set as the waterproof double-sided adhesive tape of a 5 layer structure.

  Moreover, the waterproof double-sided pressure-sensitive adhesive tape of FIG. 1 can be manufactured as follows. First, for example, an acrylic pressure-sensitive adhesive is applied to the release treatment surface of the release liner 1 and dried to form the pressure-sensitive adhesive layer 2. Then, a base material 3 made of, for example, an EPDM rubber sheet or an EVA sheet is laminated on the adhesive layer 2 to form a three-layer structure. The pressure-sensitive adhesive layer 4 is formed by applying and drying, for example, an acrylic pressure-sensitive adhesive on the surface of the substrate 3 of the three-layer structure opposite to the surface on which the pressure-sensitive adhesive layer 2 is provided. And the release liner 5 is laminated | stacked on the adhesion layer 4, and it is set as the waterproof double-sided adhesive tape of a 5 layer structure.

  Furthermore, the waterproof double-sided adhesive tape of FIG. 1 can be manufactured as follows. For example, the pressure-sensitive adhesive layer 2 is formed by applying and drying, for example, an acrylic pressure-sensitive adhesive on the base material 3 made of an EPDM rubber sheet or EVA sheet. Then, for example, the release liner 1 is laminated on the adhesive layer 2 to form a three-layer structure. The pressure-sensitive adhesive layer 4 is formed by applying and drying, for example, an acrylic pressure-sensitive adhesive on the surface of the base material 3 of the three-layer structure opposite to the surface on which the pressure-sensitive adhesive layer 2 is formed. And the release liner 5 is laminated | stacked on the adhesion layer 4, and it is set as the waterproof double-sided adhesive tape of a 5 layer structure.

  Moreover, the waterproof double-sided pressure-sensitive adhesive tape of FIG. 2 can be produced as follows. First, the adhesive layer 2 is formed by applying and drying, for example, an acrylic adhesive on one surface of the release liner 6 that has been subjected to a release treatment on both sides. Then, a base material 3 made of, for example, an EPDM rubber sheet or an EVA sheet is laminated on the adhesive layer 2 to form a three-layer structure. Next, on the surface opposite to the surface on which the adhesive layer 2 of the base material 3 is provided, for example, an acrylic adhesive is applied and dried to form an adhesive layer 4 to form a waterproof double-sided structure having a four-layer structure. Use adhesive tape.

  Furthermore, the waterproof double-sided pressure-sensitive adhesive tape of FIG. 2 can also be produced by the following procedure. First, the adhesive layer 2 is formed by applying and drying, for example, an acrylic adhesive on one surface of the substrate 3 made of, for example, an EPDM rubber sheet or an EVA sheet. And the release liner 6 by which the peeling process was performed on both surfaces is laminated | stacked on the adhesion layer 2, and it is set as a 3 layer structure. Next, on the surface opposite to the surface on which the adhesive layer 2 of the base material 3 is provided, for example, an acrylic adhesive is applied and dried to form an adhesive layer 4 to form a waterproof double-sided structure having a four-layer structure. Use adhesive tape.

[Example]
The structure of the waterproof double-sided pressure-sensitive adhesive tape of the present invention will be specifically described with reference to examples. However, the waterproof double-sided pressure-sensitive adhesive tape of the present invention is not limited to this.

[Example 1]
A pressure-sensitive adhesive solution in which 0.25 parts by mass of an isocyanate-based crosslinking agent (CK-117 manufactured by Nippon Carbide Industry Co., Ltd.) is added to 100 parts by mass of an acrylic pressure-sensitive adhesive solution (Nihon Carbide Industries Co., Ltd., Nissetsu KP-2514). Was applied to a release liner with a doctor coater and dried at about 110 ° C. to form an adhesive layer having a thickness of 50 μm.

  An EPDM rubber sheet (thickness 100 μm, tensile strength 10 MPa, elongation 440%, Young's modulus 70 MPa, nanoindentation indentation depth 15 μm) is bonded onto the adhesive layer formed on this release liner. A single-sided adhesive tape was prepared. Next, in the same manner as described above, an adhesive layer having a thickness of 50 μm was formed on the release liner, and this adhesive layer was bonded to the EPDM rubber sheet side of the single-sided adhesive tape to prepare a double-sided adhesive tape.

[Example 2]
Example 1 was used except that a urethane rubber sheet (thickness 100 μm, tensile strength 40 MPa, elongation 750%, Young's modulus 100 MPa, nanoindentation depth 13 μm) was used instead of the EPDM rubber sheet. A double-sided adhesive tape was prepared.

Example 3
Double-sided pressure-sensitive adhesive tape as in Example 1 except that a 5% EVA elastomer sheet (thickness 100 μm, tensile strength 24 MPa, elongation 540%, Young's modulus 300 MPa, nanoindentation indentation depth 5 μm) was used. Was made.

Example 4
Double-sided pressure-sensitive adhesive tape as in Example 1 except that a 10% EVA elastomer sheet (thickness 100 μm, tensile strength 22 MPa, elongation rate 600%, Young's modulus 250 MPa, nanoindentation indentation depth 8 μm) was used. Was made.

Example 5
EVA elastomer sheet consisting of three layers with an outer layer VA% of 5%, an inner layer VA% of 10%, and an outer layer-inner layer composition ratio of 1: 3 (thickness 100 μm, tensile strength 23 MPa, elongation 580%, Young's modulus) A double-sided pressure-sensitive adhesive tape was produced in the same manner as in Example 1 except that 270 MPa and a nanoindentation depth of 7 μm were used.

Example 6
EVA elastomer sheet consisting of three layers with an outer layer VA% of 5%, an inner layer VA% of 20%, and a composition ratio of the outer layer to the inner layer of 1: 3 (thickness 100 μm, tensile strength 20 MPa, elongation 630%, Young's modulus) A double-sided pressure-sensitive adhesive tape was produced in the same manner as in Example 1 except that 200 MPa and a nanoindentation depth of 12 μm were used.

[Comparative Example 1]
Example 1 except that a polyethylene terephthalate sheet (PET) (thickness 100 μm, tensile strength 147 MPa, elongation rate 100%, Young's modulus 3000 MPa, nanoindentation indentation depth 1 μm) was used in place of the EPDM rubber sheet. A double-sided adhesive tape was produced in the same manner as described above.

[Comparative Example 2]
Except for using a polyethylene (PE) foam base material (thickness 100 μm, tensile strength 8 MPa, elongation rate 600%, Young's modulus 4 MPa, nanoindentation indentation depth 20 μm) instead of EPDM rubber sheet A double-sided pressure-sensitive adhesive tape was produced in the same manner as in Example 1.

[Comparative Example 3]
Example 1 except that a polypropylene sheet (PP) (thickness 100 μm, tensile strength 550 MPa, elongation 600%, Young's modulus 600 MPa, nanoindentation depth 3 μm) was used instead of the EPDM rubber sheet. Similarly, a double-sided adhesive tape was produced.

Each obtained double-sided pressure-sensitive adhesive tape was evaluated by the test method described below, and the results shown in Table 1 were obtained.

(Shock absorption test)
A double-sided adhesive tape was punched into a frame mold having an outer diameter of 25 mm × 25 mm, a width of 0.8 mm, 1 mm, or 2 mm, sandwiched between two acrylic plates having an outer diameter of 50 mm × 50 mm, loaded with a weight of 1 kg, and left at 23 ° C. for 24 hours. A test piece was used. An iron ball having a mass of 16 g was dropped from the position of a height of 150 mm to the center of the test piece, and the impact force applied to the test piece was measured. An accelerometer (2304A manufactured by Showa Keiki Co., Ltd.) was used to measure the impact force, and the accelerometer was installed on the surface opposite to the surface on which the iron ball was dropped. As an evaluation method, attention is paid to the peak height of the first wave of the acceleration attenuation curve measured as shown in FIG. 8, and the impact is absorbed more as the peak height is lower.

(Impact resistance test)
A double-sided adhesive tape was punched into a frame mold having an outer diameter of 50 mm × 100 mm, a width of 0.8 mm, 1 mm, or 2 mm, sandwiched between two acrylic plates having an outer diameter of 60 mm × 120 mm, and a weight of 1 kg was placed and left at 23 ° C. for 24 hours. A test piece was used. This test piece was dropped from a height of 1 m onto a concrete floor, and the number of drops until the test piece was separated was measured.

(Iron ball drop test)
Double-sided adhesive tape is punched into a 45mm x 60mm, width 0.8mm, 1mm, or 2mm frame mold, 2mm thick, 60mm x 75mm, 10mm wide frame-type polycarbonate plate and 1mm thick, 50mm x 65mm A test piece was sandwiched between polycarbonate plates, loaded with a weight of 1 kg and left at 23 ° C. for 24 hours. In the center of this test piece, a 300 g iron ball was dropped from a position of 20 cm in height, and it was evaluated whether or not the tape was peeled off (O: no peeling, x: peeling).

(Waterproof test)
The test was conducted based on the IPX7 standard (JIS C 0920 / IEC 60529). A double-sided adhesive tape was punched into a frame mold having an outer diameter of 50 mm × 100 mm, a width of 0.8 mm, 1 mm, or 2 mm, sandwiched between two acrylic plates having an outer diameter of 60 mm × 120 mm, and a weight of 1 kg was placed and left at 23 ° C. for 24 hours. A test piece was used. After leaving this test piece in 1 m depth of water for 30 minutes, the test piece was taken out and evaluated for the presence or absence of water immersion inside the frame-type double-sided pressure-sensitive adhesive tape (O: no water immersion, x: water immersion).

(Air leak test)
Double-sided adhesive tape is punched into a 45mm x 60mm, 0.8mm, 1mm, or 2mm frame, and a hole is drilled to allow air to flow into the center. A test piece was sandwiched between 120 mm acrylic plates, loaded with a mass of 1 kg and left at 23 ° C. for 24 hours. 30 kPa of air was allowed to flow into the test piece for 5 minutes to evaluate whether the air leaked to the outside (O: no air leak, x: air leaked).

  Further, the VA% of the outer layer of the EVA base material having a three-layer structure is not particularly limited. However, in order to clarify a preferable range, experiments and evaluations are performed in the ranges shown in Examples 1 to 4 in Table 2. Went. The inner layer has a VA% of 10%, the composition ratio of the inner layer to the outer layer is 1: 1, the base material has a thickness of 100 μm, and an adhesive is provided in the same manner as in Example 1 to form a frame with a width of 0.8 mm. It was punched and used for the test. The evaluation results are shown in Table 2.

  When the outer layer VA% was less than 0.5%, the impact absorbability was impaired. Further, when the outer layer VA% exceeds 15%, the surface becomes sticky, and therefore, when the base material alone is made into a roll, blocking occurs. As a result, it can be seen from Table 2 that the outer layer VA% is preferably in the range of 1 to 10%.

  The Young's modulus and the indentation depth required by the nanoindentation method for the substrates of Examples 2 and 3 were in the ranges described above. That is, the Young's modulus obtained from the load-displacement curve when the indenter is pressed by the nanoindentation method is in the range of 5 to 500 MPa, and the indentation depth when the indenter is pressed by the nanoindentation method is It is in the range of 4 to 15 μm.

Further, the VA% of the inner layer of the EVA base material having a three-layer structure is not particularly limited, but in order to clarify a preferable range, experiments and evaluations are performed in the ranges shown in Examples 5 to 9 in Table 3. Went. The VA% of the outer layer is 5%, the composition ratio of the thickness of the inner layer to the outer layer is 1: 1, the thickness of the base material is 100 μm, and the adhesive is provided in the same manner as in Example 1, and the frame shape has a width of 0.8 mm. It was punched and used for the test. The evaluation results are shown in Table 3.

  When the inner layer VA% is less than 0.5%, the impact absorbability is impaired, and when the inner layer VA% exceeds 40%, the film forming property during film processing is deteriorated. Therefore, it can be seen from Table 3 that the inner layer VA% is preferably 1 to 40%. In addition, the Young's modulus and indentation depth of the indenter which were calculated | required by the nanoindentation method of the base material of Examples 6-8 were said range. That is, the Young's modulus obtained from the load-displacement curve when the indenter is pressed by the nanoindentation method is in the range of 5 to 500 MPa, and the indentation depth when the indenter is pressed by the nanoindentation method is It is in the range of 4 to 15 μm.

  Further, the composition ratio of the thickness of the inner layer and the outer layer of the EVA base material having a three-layer structure is not particularly limited, but in order to clarify a preferable range, the ranges shown in Examples 10 to 16 in Table 4 Experiments and evaluations were conducted. The outer layer has a VA% of 5%, the inner layer has a VA% of 10%, the base material has a thickness of 100 μm, and an adhesive is provided in the same manner as in Example 1. did. The evaluation results are shown in Table 4.

  When the film is formed with an inner layer / outer layer composition ratio of 1/5 or more, the film formability deteriorates due to problems such as warpage and thickness unevenness. On the other hand, when the film is formed with an inner layer / outer layer composition ratio of 5/1 or more, film formability deteriorates due to problems such as warpage and thickness unevenness. Therefore, from Table 4 above, the ratio of the thickness dimension of the outer layer and the inner layer of the substrate, the thickness dimension of the outer layer: the thickness dimension of the inner layer is preferably 1: 4 to 4: 1. I understand. In addition, the Young's modulus calculated | required by the nanoindentation method of the base material of Examples 11-15 and the indentation depth of the indenter were said range. That is, the Young's modulus obtained from the load-displacement curve when the indenter is pressed by the nanoindentation method is in the range of 5 to 500 MPa, and the indentation depth when the indenter is pressed by the nanoindentation method is It was in the range of 4-15 μm.

  According to the above Examples 1 to 5, it is possible to provide a waterproof double-sided pressure-sensitive adhesive tape that does not deteriorate waterproofness even if the tape is narrowed, and that is excellent in impact resistance and shock absorption. Become.

DESCRIPTION OF SYMBOLS 1 Release liner 2 Adhesive layer 3 Base material 4 Adhesive layer 5 Release liner 6 Release liner

Claims (8)

A substrate made of an elastomer non-foam, and an adhesive layer made of an adhesive and disposed on both the front and back surfaces of the substrate ,
The base material is a waterproof double-sided pressure-sensitive adhesive tape having a thickness of 50 μm or more and 1000 μm or less,
The base material has a Young's modulus in a range of 5 to 500 MPa determined from a load-displacement curve when the indenter is pushed by a nanoindentation method,
The indentation depth when the indenter is pushed by the nanoindentation method is in the range of 4 to 15 μm,
A double-sided adhesive tape for waterproofing, characterized in that at least one of the conditions is satisfied . The waterproof double-sided pressure-sensitive adhesive tape according to claim 1, wherein the base material is at least one selected from ethylene propylene rubber (EPDM), urethane rubber, and ethylene-vinyl acetate copolymer (EVA).   The waterproof double-sided pressure-sensitive adhesive tape according to claim 1 or 2, wherein the base material has a three-layer structure of a pair of outer layers and an inner layer sandwiched between the outer layers. The base material comprises an ethylene-vinyl acetate copolymer as a main component,
The waterproof double-sided pressure-sensitive adhesive tape according to claim 3, wherein VA% of the outer layer is 1 to 10%, and VA% of the inner layer is 1 to 40%.   The ratio of the thickness dimension of the outer layer and the inner layer of the base material, the thickness dimension of the outer layer: the thickness dimension of the inner layer is 1: 4 to 4: 1. Or the double-sided adhesive tape for waterproofing according to 4.   The double-sided pressure-sensitive adhesive tape for waterproofing according to any one of claims 1 to 5, which is used for a portable device.   The waterproof double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 5, which is used for an outdoor display device. The waterproof double-sided pressure-sensitive adhesive tape according to claim 6 or 7, wherein a use width dimension is 0.8 to 5.0 mm.

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