JP6624480B2 - Adhesive tape and method for producing the same - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive tape having a foam layer that can be used, for example, in the production of electronic devices and the like.

BACKGROUND ART Adhesive tapes are widely used in the production of electronic devices such as OA devices and home electric appliances, for example, because of their excellent workability and high adhesion reliability.
In recent years, electronic devices, particularly personal computers, digital video cameras, electronic organizers, mobile phones, PHSs, smartphones, game devices, electronic books, and other portable electronic terminals have been required to be smaller and thinner. In addition, the adhesive tape and the like constituting the portable electronic terminal are also required to be reduced in thickness.

  In general, in the above display devices, an adhesive tape having a foaming layer having a cushioning property is often attached to the back surface of the display for the purpose of preventing the display from cracking or pooling (a wavy phenomenon of liquid crystal density) ( Patent Document 1).

  However, since the pressure-sensitive adhesive tape having the foamed layer is very flexible, bubbles are often involved at the time of sticking and become wrinkled in many cases. In particular, the above problem has been noticeable in the case where the positioning is performed by a press machine at the time of sticking and lamination is performed several minutes later.

JP-A-2004-309699

  The problem to be solved by the present invention is to quickly remove air bubbles from the interface with the adherend, prevent the air bubbles from remaining at the interface, and have excellent adhesiveness and cushioning properties. The purpose is to provide an adhesive tape.

  The present inventors are an adhesive tape having two or more adhesive portions (B) on the foam layer (A), the resin film layer (C), and the resin film (C) side, wherein the two or more adhesive portions ( The problem has been solved by an adhesive tape characterized in that there is an area without an adhesive part (B) between B) and the area is connected to an end of the adhesive tape.

  ADVANTAGE OF THE INVENTION The pressure-sensitive adhesive tape of the present invention quickly escapes air bubbles from the interface with the adherend, hardly remains air bubbles at the interface, and is excellent in cushioning property and adhesive strength while being thin. Therefore, the pressure-sensitive adhesive tape of the present invention can prevent the display from cracking or pooling without lowering the production efficiency of the final product or its components. Therefore, the pressure-sensitive adhesive tape of the present invention can be suitably used, for example, for bonding to a non-display surface side of a display of a display device.

It is the top view which looked at the adhesive tape which has the adhesive part of a substantially rhombus shape from the adhesive part side. It is the top view which looked at the adhesive tape which has a substantially circular adhesive part from the adhesive part side. It is the top view which looked at the adhesive tape which has a substantially hexagonal adhesive part from the adhesive part side. It is the top view which looked at the adhesive tape which has a substantially square-shaped adhesive part from the adhesive part side. FIG. 19 is a top view of a surface having an adhesive portion of the adhesive tape obtained in Example 20. It is a mimetic diagram showing the manufacturing method of the polyurethane foam layered product of the present invention.

(Adhesive tape)
The pressure-sensitive adhesive tape of the present invention is a pressure-sensitive adhesive tape having two or more pressure-sensitive adhesive portions (B) on a foam layer (A), a resin film layer (C), and a resin film (C) side, wherein the two or more pressure-sensitive adhesive portions Between (B), there is a region having no adhesive portion (B), and the region is connected to an end of the adhesive tape.

  Specific embodiments of the pressure-sensitive adhesive tape of the present invention include a foam layer (A), a resin film layer (C), a single-sided pressure-sensitive adhesive tape having two or more pressure-sensitive adhesive portions (B) on the resin film (C) side, Is a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer also on the foam layer (A) side. Further, an intermediate layer such as a metal foil layer may be provided between the resin film layer and the foam layer (A) or between the resin film (C) and the adhesive portion (B).

  Between the two or more adhesive parts (B), there is a region where the component constituting the adhesive part (B) does not exist or may exist to such an extent that it does not exhibit adhesiveness. Therefore, when the pressure-sensitive adhesive tape of the present invention is observed from the side, it is observed that the pressure-sensitive adhesive portion (B) has a convex shape with respect to the surface of the resin film (C).

  Further, the pressure-sensitive adhesive tape of the present invention has a configuration in which a region having no pressure-sensitive adhesive portion (B) between the two or more pressure-sensitive adhesive portions (B) communicates with a part of an end (outer edge) of the pressure-sensitive adhesive tape. . By using the pressure-sensitive adhesive tape having the above-described configuration, when the pressure-sensitive adhesive tape is applied to the adherend, air bubbles pass through the region and from the interface between the pressure-sensitive adhesive tape and the adherend to the outside. This makes it possible to prevent poor appearance caused by the above and to maintain excellent cushioning properties, adhesive strength, and the like.

  As the pressure-sensitive adhesive tape of the present invention, it is preferable to use a tape having a total thickness of 300 μm or less, more preferably 30 μm to 250 μm, and even more preferably 50 μm to 200 μm. It is particularly preferable to use one having a thickness of 50 μm to 100 μm, for example, in order to contribute to a reduction in thickness of a portable electronic terminal or the like. The total thickness of the pressure-sensitive adhesive tape was measured in accordance with JIS K6250 by a method using a dial gauge, with the contact surface of the dial gauge being flat, the diameter being 8 mm, and the load being 0.51 N. Refers to the thickness of the tape and does not include the thickness of the release liner. The thickness can be measured, for example, with a thickness meter FFG-6 manufactured by Ozaki Seisakusho.

  As the pressure-sensitive adhesive tape of the present invention, it is preferable to use a tape having an adhesive force of 1 N / 20 mm to 12 N / 20 mm, and it is more preferable to use a tape having an adhesive force of 1.5 N / 20 mm to 10 N / 20 mm. The use of a material having an adhesive force of 3N / 20mm to 8N / 20mm is thin even when a hole or the like is not provided in a part thereof. This is preferable for obtaining a pressure-sensitive adhesive tape that is easily removed and has excellent adhesive strength. On the other hand, when more excellent adhesiveness is required, it is more preferable to use a pressure-sensitive adhesive tape having an adhesive force of 4 N / 20 mm to 10 N / 20 mm, preferably 4.5 N / 20 mm to 8 N /. It is more preferable to use one having an adhesive strength of 20 mm.

  In addition, the said adhesive force points out the value measured according to JISZ0237. Specifically, the adhesive force is such that a surface having an adhesive portion (B) of an adhesive tape and a clean and smooth stainless steel plate (BA plate) are overlapped, and the upper surface thereof is reciprocated once using a 2 kg roller. The pressure was measured at 23 ° C. and 50% RH for 1 hour, and then the adhesive tape was peeled off at a speed of 0.3 m / min in the 180 ° direction.

  As the pressure-sensitive adhesive tape of the present invention, even if it is thin, it can be prevented from being peeled off over time due to the repulsive force of the adherend and the foam layer (A) and the components falling off, and especially used at a relatively high temperature. Even in the case where the above-mentioned peeling is prevented, it is preferable to use one having a holding force of 2 mm or less, more preferably 0.5 mm or less, and 0.1 mm or less. It is more preferred to use

  The holding force indicates a value measured according to JISZ0237. Specifically, the holding force is applied by stacking the surface of the adhesive tape having the adhesive portion (B) on a clean and smooth stainless steel plate (hairline), and making one reciprocation on the upper surface using a 2 kg roller. The test piece was left under the condition of 23 ° C. and 50% RH for 1 hour. Next, in an environment of 100 ° C., the stainless steel plate constituting the test piece was fixed vertically, and left for 24 hours in a state where a load of 100 g was applied to the lower end of the adhesive tape constituting the test piece. This is a value obtained by measuring the displacement distance between the stainless steel plate and the adhesive tape with a caliper.

(Adhesive part B)
First, the adhesive portion (B) constituting the adhesive tape of the present invention will be described.
The adhesive portion (B) is provided on the resin film (C) directly or via another layer. Between the two or more adhesive parts (B), there is a region where the component constituting the adhesive part (B) does not exist or may exist to such an extent that it does not exhibit adhesiveness.
The thickness of the adhesive portion (B) is not particularly limited, but is preferably 0.5 to 30 μm, more preferably 1 to 10 μm, and most preferably 2 to 5 μm.

  In addition, a region having no adhesive portion (B) between the two or more adhesive portions (B) has a configuration that communicates with a part of an end (outer edge) of the adhesive tape. By using the pressure-sensitive adhesive tape having the above configuration, even when a hole or the like is not provided in a part of the pressure-sensitive adhesive tape, when the pressure-sensitive adhesive tape is attached to the adherend, bubbles are easily removed from the interface between them. Therefore, it is possible to prevent poor appearance due to swelling of the pressure-sensitive adhesive tape, and to maintain excellent heat conductivity (heat dissipation), adhesive strength, and the like.

  The shape of the adhesive portion (B) is a substantially square shape, a substantially hexagonal shape, a substantially circular shape, or the like when the adhesive tape of the present invention is observed from one surface (a) of the resin film (C). The shape is preferably a substantially circular shape, since air bubbles can easily escape from the interface with the adherend (air bleeding property) and good adhesive strength can be maintained.

  The substantially circular shape is not particularly limited, but it is preferable that the ratio (maximum diameter / minimum diameter) of the maximum diameter to the minimum diameter of any one adhesive portion is 1 to 4. More preferably, it is 1-2, and most preferably, it is 1-1.5. An example of the substantially circular shape is a shape as shown in FIG. The adhesive portions having the above shapes are basically independent of each other, but there may be a portion where two or more adhesive portions are partially connected as shown in FIG.

  Examples of the substantially square shape include shapes such as substantially square, substantially rectangular, substantially trapezoidal, substantially rhombic, and the substantially rhombic shape allows air bubbles to easily escape from the interface with the adherend (air bleeding property). Moreover, it is preferable because good adhesive strength can be maintained.

  The “substantially” such as the substantially square shape and the substantially hexagonal shape refers to, for example, when a release liner or the like is attached to the surface of the adhesive portion (B), or when the adhesive tape is wound around a roll. When the adhesive portion (B) is pressed, the square and hexagonal corners include a rounded shape and a straight portion includes a curved portion.

  It is preferable that the corners of the substantially square shape are substantially rhombic in which the angle of the corners facing the flow direction of the adhesive tape is less than 90 °, and the angle is in the range of 45 ° to 70 °. It is more preferable because air bubbles can easily escape from the interface with the body (air bleeding property) and good adhesive strength can be maintained.

  Further, it is preferable that the arbitrary adhesive portions (b1) and the adhesive portions (b2) constituting the two or more adhesive portions (B) do not face each other in the flow direction and the width direction of the adhesive tape.

  Further, the pressure-sensitive adhesive tape is often cut into an arbitrary shape depending on the use or the like and used. At this time, since the adhesive portion (b1) and the adhesive portion (b2) are arranged so as not to face each other with respect to the flow direction and the width direction, when the adhesive tape is cut at an arbitrary position, the end portion is formed. Since the adhesive portion (B) exists in a part of the adhesive tape, peeling of the adhesive tape can be suppressed.

  Further, the contact area (r2) between the adhesive section (b1) and the release liner attached to the surface thereof with respect to the major diameter of the contact area (r1) between the adhesive section (b1) and the support measured by the method. ) The ratio with the major axis [the major axis of the contact region (r2) / the major axis of the contact region (r1)] × 100 is preferably 97% to 110%, and more preferably 97% to 105%. It is more preferable in order to achieve both easy removal of air bubbles from the interface with the adherend and more excellent adhesiveness.

  As the pressure-sensitive adhesive tape of the present invention, of the pressure-sensitive adhesive portions (b1) satisfying the requirement of the ratio [contact area (s2) / contact area (s1)] × 100 among all the pressure-sensitive adhesive portions provided on the surface of the support. It is preferable to use one having an occupying ratio of 50% to 100%, more preferably 80% to 100%, even more preferably 90% to 100%, It is particularly preferable to use those having 95% to 100% in order to maximize the effects of the present invention.

  The distance between the arbitrary adhesive portion (b1) selected from the two or more adhesive portions (B) and the adhesive portion (b2) close to the adhesive portion (b1) is preferably 0.5 mm or less, more preferably. Is 0.05 mm to 0.2 mm, more preferably 0.06 mm to 0.15 mm, and 0.08 mm to 0.13 mm when no hole or the like is provided in a part of the adhesive tape. However, it is particularly preferable because bubbles can easily escape from the interface with the adherend (air bleeding property) and good adhesive strength can be maintained.

The adhesive portion (B) any adhesive portion selected from (b1) size per piece is preferably an area 0.001 mm ² 100 mm ^2, it is 0.01 mm 2 25 mm ² more ^preferably, more preferably from 0.015mm ² ~16mm 2, it is 0.02 mm ² to 5 mm ² is even the case without the hole or the like in a part of the adhesive tape to an adherend This is particularly preferable because bubbles can easily escape from the interface (air bleeding property) and good adhesive strength can be maintained.

  The adhesive portion (B) preferably has 10 to 1,000,000, and more preferably 1000 to 50,000 in the area of the adhesive tape of the present invention (square with 5 cm in the flow direction and 5 cm in the width direction). More preferably, the presence of 5000 to 40,000 air bubbles is easy to escape from the interface with the adherend (air bleeding property) and good even when holes or the like are not provided in a part of the adhesive tape. It is particularly preferable because the adhesive strength can be maintained.

  In addition, as the pressure-sensitive adhesive tape, air bubbles can easily escape from the interface with the adherend during application (air bleeding property), good adhesive strength can be maintained, and the adherend such as a graphite sheet is thinner. Even when the adhesive tape is formed, from the viewpoint of effectively preventing appearance defects due to the shape of the adhesive portion, a range of 120 pieces to a predetermined area (1 cm in the flow direction and 1 cm in the width direction) of the adhesive tape is used. It is preferable to use one having 2,000 adhesive parts, more preferably one having 280 to 1600 adhesive parts, and more preferably one having 520 to 1200 adhesive parts. More preferred.

  In addition, the number of the above-mentioned adhesive portions can be determined by observing an arbitrary range (a square with a flow direction of 1 cm and a square with a width direction of 1 cm) or (a square with a flow direction of 5 cm and a width direction of 5 cm) with an electron microscope. You can ask.

  It is preferable that the ratio of the area having the adhesive portion (B) to the area of the one surface (a) is 10% to 99%. It is more preferably 20% to 90%, more preferably 30% to 80%, and most preferably 35% to 80%. It is possible to form a substantially circular pressure-sensitive adhesive portion which will be described later to be within the above range. As a result, even when a hole or the like is not provided in a part of the pressure-sensitive adhesive tape, air bubbles escape from the interface with the adherend. It is particularly preferable because an adhesive tape which is easy (air bleeding property) and can maintain good adhesive strength can be efficiently produced. In addition, the ratio of the above-mentioned region is an area ratio of the adhesive portion (B) in an area of a square tape having a flow direction of 5 cm and a width direction of 5 cm.

  The peak temperature of the loss tangent of the adhesive portion (B) based on the dynamic viscoelasticity spectrum measured at a frequency of 1 Hz is not particularly limited, but is preferably −30 ° C. to 20 ° C., The temperature is more preferably from 20 ° C to 10 ° C, and from -10 ° C to 5 ° C, air bubbles can easily escape from the interface with the adherend (air bleeding property), and good adhesive strength can be maintained. As a result, it is more preferable because poor appearance due to swelling or the like of the pressure-sensitive adhesive tape and deterioration in performance such as heat conductivity (heat dissipation), heat resistance, and adhesive strength can be more effectively prevented.

  In the above dynamic viscoelasticity measurement, a viscoelasticity tester (trade name: Ares 2KSTD, manufactured by Rheometrics Co., Ltd.) was used, and a test piece was sandwiched between parallel disks serving as measurement units of the tester, and stored at a frequency of 1 Hz. The elastic modulus (G ′) and the loss elastic modulus (G ″) are measured. The loss tangent is calculated by an expression represented by tan δ = (G ″) / (G ′). The peak temperature refers to a peak temperature confirmed by a tan δ spectrum in a measured temperature range (−50 ° C. to 150 ° C.).

  As the test piece, a pressure-sensitive adhesive layer having a thickness of 0.5 mm to 2.5 mm formed using a pressure-sensitive adhesive used for forming the pressure-sensitive adhesive portion (B) can be used.

  In addition, as the test piece, of a plurality of the pressure-sensitive adhesive tapes of the present invention laminated, a pressure-sensitive adhesive layer having a total thickness of 0.5 mm to 2.5 mm can be used. When the test pieces having the different configurations are used, the value of tan δ changes, but when the total thickness of the pressure-sensitive adhesive layer (B) occupied in the test pieces is the same, the peak temperature substantially decreases. It does not change. Therefore, in the measurement of the peak temperature, any test piece may be used.

  As the adhesive portion (B), those having a gel fraction of 10% by mass to 60% by mass are preferably used, and those having a gel fraction of 20% by mass to 55% by mass are more preferably used. It is preferable to use a gel having a gel fraction of 30% by mass to 50% by mass, since the surface shape of the adhesive portion (B) is easily maintained even if it is thin, so that a change with time is prevented. Air bubbles can be easily removed from the interface between the adherend and the adhesive portion (B), and as a result, poor appearance due to swelling of the adhesive tape, thermal conductivity (heat dissipation) and heat resistance This is more preferable because it is possible to more effectively prevent performance deterioration such as properties and adhesive strength. In addition, the said gel fraction points out the value measured by the following method.

In addition, the said gel fraction points out the value measured by the method shown below.
(1) The release liner (D) was coated with the above-mentioned pressure-sensitive adhesive so that the thickness after drying was 50 μm on the release-treated surface of the release liner (D). The pressure-sensitive adhesive layer was formed by aging for 2 days in an environment of ° C.
(2) A test piece was obtained by cutting the pressure-sensitive adhesive layer into a square having a length of 50 mm and a width of 50 mm.
(3) After measuring the mass (G1) of the test piece, the test piece was immersed in toluene at 23 ° C. for 24 hours.
(4) After the immersion, a mixture of the test piece and toluene was filtered using a 300-mesh wire net to extract insoluble components in toluene. The mass (G2) of the insoluble component dried at 110 ° C. for one hour was measured.
(5) The gel fraction was calculated based on the mass (G1), the mass (G2) and the following equation.
Gel fraction (% by mass) = (G2 / G1) × 100

  It is preferable to use the adhesive part (B) having a thickness of 1 μm to 6 μm, and to use the adhesive part (B) having a thickness of 2 μm to 5 μm because air bubbles are generated from the interface between the adherend and the adhesive part (B). Is easily removed, and as a result, poor appearance due to swelling or the like of the pressure-sensitive adhesive tape and deterioration in performance such as thermal conductivity, heat resistance, and adhesive strength can be more effectively prevented, which is more preferable. The thickness of the adhesive portion (B) is measured by a method using a dial gauge in accordance with JIS K6783, under the condition that the contact surface of the dial gauge is flat, the diameter is 5 mm, and the load is 1.23N. Refers to the thickness of the double-sided adhesive tape.

  The adhesive part (B) is, for example, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a urethane adhesive, a polyester adhesive, a styrene-diene block copolymer adhesive, a vinyl alkyl ether adhesive. And a known pressure-sensitive adhesive such as a polyamide-based pressure-sensitive adhesive, a fluorine-based pressure-sensitive adhesive, an adhesive with improved creep characteristics, and a radiation-curable pressure-sensitive adhesive. Above all, it is preferable to use an adhesive part obtained by using an acrylic adhesive as the adhesive part (B) because of excellent adhesion reliability.

  When using a tape having an adhesive portion or an adhesive layer on both sides of the foam layer as the adhesive tape of the present invention, even if the adhesive portion or the adhesive layer has the same composition or gel fraction, different compositions or gels An adhesive part or an adhesive layer having a fraction may be used.

  As the acrylic pressure-sensitive adhesive, one containing an acrylic polymer can be used.

  As the acrylic polymer, those obtained by polymerizing a monomer component containing a (meth) acrylic monomer such as an alkyl (meth) acrylate can be used.

  Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylate. ) Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate , 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, (meth) acrylic acid Undecyl, dodecyl (meth) acrylate, tridecyl (meth) acrylate, Tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, etc. Alternatively, two or more kinds can be combined. Among them, as the alkyl (meth) acrylate, it is preferable to use an alkyl (meth) acrylate having 1 to 20 carbon atoms in the alkyl group, and 4 to 18 carbon atoms in the alkyl group. It is more preferable to use the (meth) acrylic acid alkyl ester. Examples of the alkyl group include a linear or branched alkyl group.

  As the acryl group, an alkyl (meth) acrylate having 4 to 18 carbon atoms is preferably butyl (meth) acrylate because the surface shape of the pressure-sensitive adhesive layer (B) is easily maintained. This is preferable for easily obtaining a pressure-sensitive adhesive tape which can easily prevent changes over time, easily release air bubbles from the interface with the adherend (air-removing property), and maintain good adhesive strength.

  As the (meth) acrylic monomer, in addition to those described above, monomers having a carboxyl group such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and anhydrides thereof A monomer having a sulfonic acid group such as sodium vinyl sulfonate; a monomer having a cyano group such as acrylonitrile; an amide group such as acrylamide, methacrylamide, N-vinylpyrrolidone, N, N-dimethyl (meth) acrylamide A monomer having a hydroxyl group such as hydroxyalkyl (meth) acrylate and glycerin dimethacrylate; a monomer having an amino group such as aminoethyl (meth) acrylate and (meth) acryloylmorpholine; Imido groups such as cyclohexylmaleimide and isopropylmaleimide Monomer having an epoxy group such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; monomer having an isocyanate group such as 2-methacryloyloxyethyl isocyanate; triethylene glycol di ( (Meth) acrylate, diethylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, tri Use monomers such as methylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, divinylbenzene alone or in combination of two or more It can be.

  Examples of the monomer include, in addition to the (meth) acrylic monomer, aromatic vinyl compounds such as styrene and substituted styrene; olefins such as ethylene, propylene and butadiene; vinyl esters such as vinyl acetate; Vinyl chloride or the like can also be used.

  The acrylic polymer can be produced by polymerizing the monomer by a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method, or the like, and the solution polymerization method may be employed. This is preferable for improving the production efficiency of the acrylic polymer.

  Examples of the solution polymerization method include a method in which the monomer, the polymerization initiator, and the organic solvent are mixed and stirred at a temperature of preferably 40 ° C to 90 ° C to perform radical polymerization.

  Examples of the polymerization initiator include peroxides such as benzoyl peroxide and lauryl peroxide, azo-based thermal polymerization initiators such as azobisisobutylnitrile, acetophenone-based photopolymerization initiator, benzoin ether-based photopolymerization initiator, and benzyl. A ketal-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, or the like can be used.

  The acrylic polymer obtained by the above method may be in a state of being dissolved or dispersed in an organic solvent, for example, when produced by a solution polymerization method.

  As the acrylic polymer obtained by the above method, it is preferable to use a polymer having a weight average molecular weight of 300,000 to 1.2 million, more preferably to use a polymer having a weight average molecular weight of 400,000 to 1.1 million. It is preferable to use a material having a weight-average molecular weight of 500,000 to 1,000,000 in order to obtain a pressure-sensitive adhesive tape having a more excellent adhesive strength and an easier removal of air bubbles even if it is thin.

  The weight average molecular weight refers to a value measured by gel permeation chromatography (GPC) and calculated in terms of standard polystyrene. Specifically, the weight average molecular weight can be measured using a GPC device (HLC-8329GPC) manufactured by Tosoh Corporation under the following conditions.

Sample concentration: 0.5% by mass (tetrahydrofuran solution)
Sample injection volume: 100 μl
Eluent: tetrahydrofuran Flow rate: 1.0 ml / min Measurement temperature: 40 ° C
This column: 2 TSKgel GMHHR-H (20) Guard column: TSKgel HXL-H
Detector: Differential refractometer Weight average molecular weight of standard polystyrene: 10,000 to 20 million (manufactured by Tosoh Corporation)

  As the pressure-sensitive adhesive that can be used for forming the pressure-sensitive adhesive portion (B), a pressure-sensitive adhesive containing a tackifier resin is used to form a pressure-sensitive adhesive portion having more excellent adhesive strength, tensile strength, and tensile breaking strength. Is preferred.

  Examples of the tackifying resin include a rosin-based tackifying resin, a polymerized rosin-based tackifying resin, a polymerized rosin-ester-based tackifying resin, a rosin-phenol-based tackifying resin, a stabilized rosin-ester-based tackifying resin, and a disproportionated rosin ester. A petroleum resin-based tackifying resin such as a system-based tackifying resin, a hydrogenated rosin ester-based tackifying resin, a terpene-based tackifying resin, a terpene-based tackifying resin, and a styrene-based tackifying resin can be used.

  As the tackifier resin, it is possible to use a combination of a rosin-based tackifier resin and a petroleum resin-based tackifier resin. It is preferable in obtaining. The rosin-based tackifying resin and the petroleum resin-based tackifying resin are particularly preferably used in combination with the acrylic polymer, and include an acrylic polymer obtained by polymerizing a monomer containing (meth) butyl acrylate. It is preferable to use them in combination in order to obtain a pressure-sensitive adhesive tape having a more excellent adhesive strength and an easier removal of air bubbles even if it is thin.

  Further, as the tackifying resin, it is preferable to use a tackifying resin which is liquid at normal temperature in order to further improve the initial adhesive strength of the pressure-sensitive adhesive portion (B). Examples of the tackifying resin that is liquid at normal temperature include low-molecular-weight liquid rubbers such as process oils, polyester-based plasticizers, and polybutene, and terpene phenol resins can be used. Commercially available YP products manufactured by Yasuhara Chemical Co., Ltd. -90L and the like.

  The tackifying resin is preferably used in a range of 20 parts by mass to 60 parts by mass, more preferably in a range of 30 parts by mass to 55 parts by mass, based on 100 parts by mass of the acrylic polymer. It is more preferable to obtain a pressure-sensitive adhesive tape having an improved adhesive force.

  Further, as the pressure-sensitive adhesive constituting the pressure-sensitive adhesive portion (B), in addition to the acrylic polymer and the like, if necessary, a softener, a plasticizer, a filler, an antioxidant, a colorant, and the like are contained. Can be used.

  Among them, the use of a crosslinking agent can adjust the gel fraction of the adhesive portion (B) to a suitable range, and as a result, the shape of the adhesive portion (B) can be easily maintained. This is preferable because it is easy to prevent a natural change, can easily remove bubbles from the interface between the adherend and the pressure-sensitive adhesive layer (B), and can obtain a pressure-sensitive adhesive tape having excellent adhesive strength. .

  As the crosslinking agent, for example, it is preferable to use an isocyanate crosslinking agent or an epoxy crosslinking agent.

  Examples of the isocyanate crosslinking agent include tolylene diisocyanate, naphthylene-1,5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and trimethylolpropane-modified tolylene diisocyanate. It is preferable to use a toluene diisocyanate adduct such as trimethylolpropane-modified tolylene diisocyanate. The toluene diisocyanate adduct has a structure derived from toluene diisocyanate in the molecule, and commercially available products include, for example, Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.).

  When the isocyanate crosslinking agent is used, it is preferable to use an acrylic polymer having a hydroxyl group as the acrylic polymer. The acrylic polymer having a hydroxyl group may be, for example, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate or the like as a monomer used in the production thereof. Can be used, and it is more preferable to use 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

  As the epoxy cross-linking agent, for example, Tetrad X or Tetrad C manufactured by Mitsubishi Gas Chemical Co., Ltd., or E-05X manufactured by Soken Chemical Co., Ltd. can be used.

  When the epoxy crosslinking agent is used, it is preferable to use an acrylic polymer having an acid group as the acrylic polymer. As the acrylic polymer having an acid group, it is preferable to use, for example, (meth) acrylic acid, acrylic acid dimer, itaconic acid, crotonic acid, maleic acid, maleic anhydride, and the like as monomers used in the production thereof. It is more preferable to use (meth) acrylic acid.

  As the pressure-sensitive adhesive that can be used for forming the pressure-sensitive adhesive portion (B), it is preferable to use a pressure-sensitive adhesive that contains a solvent as necessary. As the pressure-sensitive adhesive, it is preferable to use a pressure-sensitive adhesive whose viscosity is adjusted in a range of 0.1 mPa · s to 1000 mPa · s, and a pressure-sensitive adhesive whose viscosity is adjusted in a range of 1 mPa · s to 200 mPa · s. It is more preferable to use one adjusted to a range of 10 mPa · s to 100 mPa · s because the adhesive portion (B) having a predetermined shape is easily formed.

(Resin film layer (C))
Next, the resin film layer (C) constituting the pressure-sensitive adhesive tape of the present invention will be described.
As the resin film layer (C), a polyester film, a polyimide film, a polyolefin film, a polyamide film, a polyurethane film, or the like can be used. Among them, a polyethylene terephthalate film which is excellent in heat resistance, strength and low cost is most preferable.
The thickness of the resin film layer (C) is preferably 1 to 100 μm. More preferably, the thickness is 1.5 to 50 μm, and the thickness of 1.5 to 6 μm is preferable because it is thin and does not deteriorate cushioning properties.

(Release liner (D))
The pressure-sensitive adhesive tape of the present invention may have a release liner (D) on a surface in contact with the pressure-sensitive adhesive portion (B).
The release liner (D) is obtained by coating a resin film with a release agent. As the resin film, a polyester film, a polyimide film, a polyolefin film or the like can be used. Among them, a polyethylene terephthalate film is preferable because of its good heat resistance and strength and low cost. The thickness of the resin film is not particularly limited, but is preferably 25 μm to 100 μm, and more preferably 50 μm to 100 μm. When it is in the above range, unevenness of the foam layer hardly occurs when the foam layer (A) is formed, so that it is preferable.
The release agent is not particularly limited, but a silicone-based release agent is preferable because the release force can be easily adjusted.

(Foam layer (A))
The thickness of the foam layer (A) constituting the pressure-sensitive adhesive tape of the present invention is not particularly limited, but is preferably 250 μm or less, more preferably 30 μm to 200 μm, and still more preferably 50 μm to 100 μm. Things can be used. By using the foam layer (A) having a thickness in the above range, the pressure-sensitive adhesive tape can be reduced in thickness. Further, even when a hole or the like is not provided in a part of the adhesive tape, bubbles can be easily removed from the interface between the surface having the adhesive portion (B) and the adherend, and as a result, It is more preferable because poor appearance due to swelling of the pressure-sensitive adhesive tape and deterioration in performance such as cushioning property and adhesive strength can be more effectively prevented.

  The foam layer (A) preferably has a 50% compressive strength of 0.003 MPa to 1 MPa, more preferably 0.01 MPa to 0.5 MPa. It is more preferable to use one having a pressure of 02 MPa to 0.4 MPa. It is particularly preferable to use the one in the above range in order to obtain an adhesive tape having cushioning property and suitable followability to an adherend.

  As the foam layer (A), for example, a sheet-like material made of a foamed resin can be used, or a resin film (C) coated with a foam layer (A) can be used. Alternatively, a resin film (C), an adhesive portion (B), and a release liner (D) which are integrated with a foam layer (A) may be used. Among them, it is preferable to use a resin film (C), an adhesive portion (B) and a release liner (D) which are integrated with a foam layer (A) on a thin and flexible foam layer. Is particularly preferred.

  As the foam layer (A), for example, polyolefin-based foams including polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, etc., polyurethane-based foams, acrylic rubbers and other elastomers And a rubber-based foam containing the same. Among them, the foam layer (A) is particularly preferably a polyurethane-based layer which is easy to form a thin and flexible foam layer.

The polyurethane foam layer is a mixture of a raw material containing a polyisocyanate and a polyol, and a gas to generate a gas-liquid mixture.The obtained gas-liquid mixture is supplied onto a resin film. It is obtained by heating and reacting the raw materials.

The raw material of the polyurethane foam layer is a composition containing a polyisocyanate and a polyol, and may contain the following other components as necessary.
The polyisocyanate is not particularly limited, and a polyisocyanate conventionally used for producing a polyurethane foam can be used. As this polyisocyanate, 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, or the like is usually used. Besides these, 1,6-hexamethylene diisocyanate, 1,5-naphthalene diisocyanate, paraphenylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate And aromatic or aliphatic polyisocyanates, prepolymer-type polyisocyanates, and the like. Two or more polyisocyanates may be used in combination, or one type of biliary tract may be used.
The polyisocyanate is blended so that the isocyanate index is preferably 0.8 to 1.2, particularly preferably 0.9 to 1.1.

The polyol is not particularly limited, and a polyol conventionally used for producing a polyurethane foam can be used. Specifically, a polyether polyol, a polyester polyol, a polyetherester polyol which is a copolymer of a P furnace ether polyol and a polyester polyol, or the like can be used. Further, in order to improve the tensile strength, a polymer polyol can be used in combination. As the polymer polyol, for example, an ethylenically unsaturated compound such as acrylonitrile, styrene, or methyl methacrylate is preferably added to a polyether polyol in an amount of preferably 5 to 40% by mass, more preferably 10 to 30% by mass in terms of solid content, and kraft polymerization. It is a polyol.

  The average molecular weight of the polyol is preferably from 300 to 6000, more preferably from 900 to 4000. One of the above polyols may be used, or two or more may be used in combination.

As a raw material of the polyurethane foam layer other than the above, a catalyst, a foam stabilizer, a crosslinking agent and the like are contained.

Examples of the catalyst include organic tin compounds such as stannas octoate, dibutyltin diacetate and dibutyltin dilaurate; organic zinc compounds such as zinc octylate; organic nickel compounds such as nickel acetylacetoate and nickel diacetylacetoate; and iron acetylacetoate. Metal catalysts such as alkoxides and phenoxides of alkali metals or alkaline earth metals such as sodium acetate, tertiary amine catalysts such as triethylamine, triethylenediamine, N-methylmorpholine dimethylaminomethylphenol, imidazole, and the like. Acid salts and the like. Of these, organotin compounds are particularly preferred. One of the above catalysts may be used, or two or more of them may be used in combination.
The content of the catalyst is preferably 0.03 to 3 parts by mass when the polyol is 100 parts by mass. Particularly preferably, it is 0.05 to 2.0 parts by mass.

As the foam stabilizer, a silicone foam stabilizer is used. As the silicone foam stabilizer, a dimethylsiloxane compound, a polyetherdimethylsiloxane compound, a phenylmethylsiloxane compound, or the like can be used. One of the above foam stabilizers may be used, or two or more thereof may be used in combination.
The content of the foam stabilizer is preferably 1 to 20 parts by mass when the polyol is 100 parts by mass. Particularly preferably, it is 2 to 10 parts by mass.

Examples of the crosslinking agent include ethylene glycol, trimethylolpropane, etc., as initiators, ester oligomers chain-extended with ε-caplactone, high molecular weight crosslinking agents such as trifunctional polyether polyols having a molecular weight of about 300 to 700, and ethylene glycol. And short-chain diols such as diethylene glycol, glycerin, and trimethylolpropane. By using a high molecular weight crosslinking agent, a more flexible foam layer can be obtained. One type of crosslinking agent may be used, or two or more types may be used in combination.
The content of the cross-linking agent contained in the raw material of the polyurethane-based foam layer depends on the kind thereof, but is preferably 1 to 10 parts by mass, particularly preferably 2 to 5 parts by mass when the polyol is 100 parts by mass. Department.

If necessary, additives such as an ultraviolet absorber, an antioxidant, an organic and permanent filler, and a coloring agent can be added to the foam raw material.

(Production method of polyurethane foam layer)
The raw materials for producing the polyurethane foam layer are the foam raw material having the above-mentioned structure, a gas-liquid mixture containing gas, and the resin film layer (C). The gas mixed with the foam raw material is not particularly limited, and nitrogen gas, inert gas, dry air, or the like can be used. Of these, nitrogen gas is preferred. Hereinafter, the method for producing the polyurethane foam laminate will be specifically described with reference to FIG.

  The foam raw material and the gas are stirred or the like using the mixer 11 to form a gas-liquid mixture 21a. Thereafter, the gas-liquid mixture 21a is supplied so as to be applied onto the resin film layer (C) 20. Then, the surface of the gas-liquid mixture 21a to be cast is released from the upper side thereof with release paper (or release treatment). Is supplied. Then, the thickness of the uncured layer 21b made of the gas-liquid mixture 21a is adjusted by passing through the roll coater 12 or the like in the laminated state. The use of the release paper 7 does not matter, but the use of the release paper 7 makes it easy to adjust the thickness of the uncured layer 21b, and the surface of the foam layer obtained after the heat treatment (the release paper 7). Side), a skin layer can be formed. Through these steps, a three-layer laminate in which the uncured layer 21b has the resin film (C) on one surface (lower surface) and the release paper 7 on the other surface (upper surface) is obtained.

  Thereafter, the laminate is heated by a heat treatment device. As a result, the foam raw material is reacted, the uncured layer 21b is cured, and the polyurethane foam laminate 30 on which the foam layer (A) is formed can be obtained. By this manufacturing method, the polyurethane foam layer (A) and the resin film layer (C) are firmly joined. The obtained laminated body 30 may be wound into a paper tube or the like in a three-layer structure to form a roll body, or, as shown in FIG. It may be taken as a roll. Further, the sheet may be cut into a predetermined size on a production line to form a sheet. The sheets may then be stacked and packed. In this case, three layers may be stacked as they are, or two layers may be stacked.

As described above, the raw materials for producing the polyurethane foam laminate are the gas-liquid mixture 21a obtained using the foam raw material and the gas, and the resin film (C).
The method for preparing the foam raw material is not particularly limited, but preferably, a polyisocyanate and a mixture containing no polyol, a flame retardant, a catalyst, and the like (hereinafter, referred to as a "first mixture") without containing the polyisocyanate. It is a method of mixing. Incidentally, additives to be added as required are usually contained in the first mixture.

  The method for preparing the gas-liquid mixture 21a is not particularly limited. When the volume ratio of the foam material and the gas is 100% by volume in total, preferably 5 to 30% by volume and 70 to 95% by volume, respectively. %, More preferably 8 to 25% by volume and 75 to 92% by volume. By this mixing ratio, the gas-liquid mixture 21a suitable for forming the foam layer having the above specific density can be prepared. Further, the mixer 11 used for mixing the foam raw material and the gas is not particularly limited, but preferably an Oaks mixer, a Hobart mixer, or the like is used. With these mixers 11, the foam material and the gas can be uniformly mixed, the control of foaming is easy, and the foamed gas-liquid mixture 21a can be generated as a more homogeneous material. it can.

  In addition, the method of mixing the foam raw material and the gas is preferably a method of blowing a gas into a foam raw material previously stored in a mixing chamber or the like, and simultaneously mixing the foam raw material and the gas into the chamber. It is a method of supplying. In these cases, the foam raw material may separately supply the polyisocyanate and the first mixture to this chamber.

  The foam layer using the gas-liquid mixture is preferably formed by a mechanical floss method. According to this method, the volume of the gas-liquid mixture to be used and the volume of the obtained polyurethane foam can be made substantially the same. Therefore, the density of the polyurethane foam can be adjusted by the composition of the gas-liquid mixture, that is, the amount of gas introduced into the foam raw material.

  The gas-liquid mixture 21a is supplied to the surface of the resin film layer (C) 20. Thereafter, the release paper 7 is supplied from above to the surface of the gas-liquid mixture 21a to be cast to form a laminate. . Next, the three-layered laminate is heated by the heat treatment device 13 set at a predetermined temperature to react the foam material contained in the uncured layer 21b to form the foam layer (A).

  The method of heating the three-layered laminate is not particularly limited, and is appropriately selected depending on the type of the heat treatment apparatus 13 and the like.

  The heating temperature is appropriately selected according to the types of the polyol and the polyisocyanate in order to cure the foam material contained in the uncured layer 21b. The heating temperature is preferably from 120 ° C to 200 ° C, preferably from 140 ° C to 180 ° C, particularly preferably from 150 ° C to 170 ° C.

  The heating time is preferably 1 to 10 minutes, more preferably 1 to 5 minutes.

  Examples of the heat treatment device 13 include a heating furnace, a far-infrared irradiation device, and the like. When a heating furnace is used, the heat treatment can be performed while the three-layered laminate is stationary or moved by using a heat source fixed in the apparatus. At this time, hot air may be supplied. When the polyurethane foam laminate is manufactured continuously, it is preferable to heat the three-layer laminate while moving it in a heating furnace.

  The heating of the three-layer laminate can be performed from either one of the resin film side and the release paper side, or from both sides. In the present invention, it is preferable to heat the entire three-layer laminate from both sides in order to uniformly heat the whole and efficiently form a more uniform foam layer.

  When the production method of the polyurethane foam laminate is the production system shown in FIG. 6, preparation of the gas-liquid mixture 21a, supply of the gas-liquid mixture 21a onto the resin film (C) 20, and uncured layer 21b Supply of release paper and the like to the upper surface of the sheet, thickness adjustment by the roll coater 12 and the like, and heating of the three-layer laminate can be continuously advanced to continuously produce a polyurethane foam laminate. . That is, the gas-liquid mixture 21a prepared by the mixer 11 is continuously sent out, continuously supplied onto the moving resin film (C) 20 at a predetermined supply speed, and cast. The release paper 7 is supplied at the same speed as that of the resin film (C) 20 to the surface thereof, and the thickness is adjusted by the roll coater 12. Thereafter, the three-layered laminate is introduced into a heat treatment device 13 arranged in the vicinity of the roll coater 12, for example, a heating furnace. When a heating furnace is used, usually, the three-layered laminate is introduced from one of the openings, moved in the heating furnace at a moving speed equal to or close to that of the resin film (C) 20, and the other opening is formed. Can be derived from Thereby, the polyurethane foam laminate 30 having the release paper 7 is manufactured. Thereafter, if necessary, the release paper 7 is removed to obtain a polyurethane foam laminate including the foam layer (A) and the resin film layer (C).

  As described above, the polyurethane foam laminate can be produced by a mechanical floss method in which water and a foaming agent are not added to the foam raw material. Moreover, it can also be manufactured by a so-called chemical floss method in which water and / or a foaming agent is blended with the foam raw material. In this case, as the water, ion exchange water, tap water, distilled water, or the like can be used. The amount of water used is not particularly limited, but is usually 0.1 to 0.5 part by mass, particularly preferably 0.2 to 0.4 part by mass when the polyol is 100 parts by mass. Further, the foaming agent is not particularly limited, and a hydrocarbon, an alternative chlorofluorocarbon, or the like can be used. The amount of the foaming agent is not particularly limited. As described above, even in the case of the chemical floss method using a foam material mixed with water and / or a foaming agent instead of the mechanical floss method, the foaming state of the gas-liquid mixture is stably maintained, and the cell roughening is performed. A foam layer having a desired density and a desired thickness can be easily formed without causing any problems. As a result, a polyurethane foam laminate having a foam layer having excellent physical properties can be obtained.

(Production method of adhesive tape)
In the pressure-sensitive adhesive tape of the present invention, for example, (I) the foam layer (A) and the resin film (C) are integrated, but the pressure-sensitive adhesive is intermittently applied to the surface side of the resin film (C). A method of manufacturing by forming an adhesive portion (B) by drying or the like; (II) forming the adhesive portion (B) by applying the adhesive in an intermittent manner to a release liner (D) and drying to form an adhesive portion (B); (III) a method in which the adhesive is intermittently applied to a release liner (D) and dried to form an adhesive portion (B). Then, a method of forming a foam layer (A) on the resin film (C) after laminating with the resin film (C), and (IV) applying the adhesive in an intermittent manner on the resin film (C) and drying. After forming an adhesive part (B) and then bonding with a release liner (D) How foam layer (A) is formed on the resin film (C) and the like. Among them, the methods (III) and (IV) are preferable because the resin film can be made relatively thin and the productivity is excellent. Particularly, the method (IV) is most preferable.

  The pressure-sensitive adhesive is preferably applied intermittently to at least one surface (a) of the foam base material (A) by a coating method such as a gravure coating method or a slot die coating method. It is preferable to apply by a direct gravure coating method.

  The pressure-sensitive adhesive tape of the present invention has excellent adhesive strength, cushioning property, and sticking workability (bubble removal property) even if it is very thin, and therefore, for example, electronic devices such as portable electronic terminals that are required to be thinner It can be suitably used in the production scene. In particular, when used on the back surface of the display, cracking and pooling of the display device can be prevented, and thinning can be contributed.

  In addition, even when the adhesive tape is not provided with a hole or the like in a part of the adhesive tape, air bubbles are easily removed from an interface between the adherend and the adhesive portion (B), and a hole is formed for improving the sticking property. Since the processing is not required, it can be suitably used on the back surface of the display where there is a concern that the performance may be degraded due to the remaining bubbles.

  Hereinafter, embodiments of the present invention will be described in more detail.

(Preparation Example 1) Adhesive a
97.98 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid, 0.02 parts by mass of 4-hydroxybutyl acrylate, 0.2 parts by mass of azobisisobutyronitrile as a polymerization initiator, ethyl acetate The resulting solution was subjected to solution polymerization at 80 ° C. for 8 hours to obtain an acrylic polymer having a weight average molecular weight of 900,000.

  5 parts by mass of "D-135" (manufactured by Arakawa Chemical Industry Co., Ltd., polymerized rosin ester) and "KE-100" (manufactured by Arakawa Chemical Industry Co., Ltd., disproportionated rosin, based on 100 parts by mass of the acrylic polymer) Ester) 20 parts by mass and “FTR6100” (Mitsui Chemical Co., Ltd., petroleum resin) 25 parts by mass were mixed, and ethyl acetate was further added to obtain an adhesive solution adjusted to a solid content of 40% by mass. .

The adhesive a was obtained by mixing and stirring the adhesive solution and 2.0 parts by mass of “NC40” (manufactured by DIC Corporation, isocyanate crosslinking agent).
The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive a had a tan δ peak temperature of 0 ° C. and a gel fraction of 40% by mass.

(Preparation Example 2) Adhesive b
97.98 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid, 0.02 parts by mass of 4-hydroxybutyl acrylate, 0.3 parts by mass of azobisisobutyronitrile as a polymerization initiator, ethyl acetate The solution was polymerized in a solution at 90 ° C. for 6 hours to obtain an acrylic polymer having a weight average molecular weight of 500,000.

  5 parts by mass of “D-135” (manufactured by Arakawa Chemical Industry Co., Ltd., polymerized rosin ester) and “KE-100” (manufactured by Arakawa Chemical Industry Co., Ltd., disproportionated rosin ester, based on 100 parts by mass of the acrylic polymer) ) 20 parts by mass and 25 parts by mass of "FTR6100" (Petroleum resin manufactured by Mitsui Chemicals, Inc.) were mixed, and ethyl acetate was further added to obtain a pressure-sensitive adhesive solution adjusted to a solid content of 40% by mass.

The pressure-sensitive adhesive b was obtained by mixing and stirring the pressure-sensitive adhesive solution and 0.6 parts by mass of “NC40” (manufactured by DIC Corporation, isocyanate crosslinking agent).
The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive b had a tan δ peak temperature of 0 ° C. and a gel fraction of 10% by mass.

(Preparation Example 3) Adhesive c
97.98 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid, 0.02 parts by mass of 4-hydroxybutyl acrylate, 0.3 parts by mass of azobisisobutyronitrile as a polymerization initiator, ethyl acetate The solution was polymerized in a solution at 90 ° C. for 6 hours to obtain an acrylic polymer having a weight average molecular weight of 500,000.

  5 parts by mass of "D-135" (manufactured by Arakawa Chemical Industries, Ltd., polymerized rosin ester) and "KE-100" (manufactured by Arakawa Chemical Industry Co., Ltd., disproportionated rosin ester, based on 100 parts by mass of the acrylic polymer) ) 20 parts by mass and 25 parts by mass of "FTR6100" (Petroleum resin manufactured by Mitsui Chemicals, Inc.) were mixed, and ethyl acetate was further added to obtain a pressure-sensitive adhesive solution adjusted to a solid content of 40% by mass.

The adhesive solution was mixed with 3.3 parts by mass of "NC40" (manufactured by DIC Corporation, isocyanate crosslinking agent) and stirred to obtain an adhesive c.
The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive c had a tan δ peak temperature of 0 ° C. and a gel fraction of 46% by mass.

(Preparation Example 4) Adhesive d
97.98 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid, 0.02 parts by mass of 4-hydroxybutyl acrylate, 0.3 parts by mass of azobisisobutyronitrile as a polymerization initiator, ethyl acetate The solution was polymerized in a solution at 90 ° C. for 6 hours to obtain an acrylic polymer having a weight average molecular weight of 500,000.

  5 parts by mass of “D-135” (manufactured by Arakawa Chemical Industries, Ltd., polymerized rosin ester) and “KE-100” (manufactured by Arakawa Chemical Industry Co., Ltd., disproportionated rosin ester, based on 100 parts by mass of the acrylic polymer) ) 20 parts by mass and 25 parts by mass of "FTR6100" (Petroleum resin manufactured by Mitsui Chemicals, Inc.) were mixed, and ethyl acetate was further added to obtain a pressure-sensitive adhesive solution adjusted to a solid content of 40% by mass.

An adhesive d was obtained by mixing and stirring the adhesive solution and 1.2 parts by mass of "NC40" (manufactured by DIC Corporation, isocyanate-based crosslinking agent).
The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive d had a tan δ peak temperature of 0 ° C. and a gel fraction of 20% by mass.

(Preparation Example 5) Adhesive e
96.4 parts by mass of n-butyl acrylate, 3.5 parts by mass of acrylic acid, 0.1 parts by mass of 4-hydroxy-ethyl acrylate, and 0.2 parts by mass of azobisisobutyronitrile as a polymerization initiator The solution was polymerized in an ethyl acetate solution at 80 ° C. for 8 hours to obtain an acrylic polymer having a weight average molecular weight of 800,000.

  10 parts by mass of “D-135” (manufactured by Arakawa Chemical Industries, Ltd., polymerized rosin ester) and “A100” (disproportionated rosin ester, manufactured by Arakawa Chemical Industry Co., Ltd.) 10 parts by mass of the acrylic polymer Parts by mass, and ethyl acetate was further added to obtain a pressure-sensitive adhesive solution adjusted to a solid content of 40% by mass.

The adhesive solution was mixed with 1.3 parts by mass of “NC40” (manufactured by DIC Corporation, isocyanate crosslinking agent) and stirred to obtain an adhesive e.
The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive e had a tan δ peak temperature of −15 ° C. and a gel fraction of 40% by mass.

(Preparation Example 6) Adhesive f
44.9 parts by mass of n-butyl acrylate, 50 parts by mass of 2-ethylhexyl acrylate, 3 parts by mass of vinyl acetate, 2 parts by mass of acrylic acid, and 0.1 part by mass of 4-hydroxybutyl acrylate Using 0.1 mass part of butyronitrile as a polymerization initiator, solution polymerization was performed in an ethyl acetate solution at 70 ° C. for 10 hours to obtain an acrylic polymer having a weight average molecular weight of 800,000.

  To 100 parts by mass of the acrylic polymer, 10 parts by mass of "D-135" (manufactured by Arakawa Chemical Industries, Ltd., polymerized rosin ester) were mixed, and the solid content was adjusted to 40% by mass by further adding ethyl acetate. An adhesive solution was obtained.

The pressure-sensitive adhesive f was obtained by mixing and stirring 1.3 parts by mass of the pressure-sensitive adhesive solution and "NC40" (manufactured by DIC Corporation, isocyanate crosslinking agent).
The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive f had a tan δ peak temperature of −25 ° C. and a gel fraction of 40% by mass.

(Example 1)
Using a gravure coater, dot-print the above-mentioned pressure-sensitive adhesive a on “PET50 × 1J0” (a release liner having a silicone-based release-treated surface on the surface of a polyester film having a thickness of 50 μm, manufactured by Nipa Corporation), and printing at 100 ° C. for 1 minute. By drying, an approximately diamond-shaped island-shaped adhesive portion having a thickness of 2 μm as shown in FIG. 1 was obtained. In addition, the distance between an arbitrary adhesive portion and the adhesive portion adjacent to the arbitrary adhesive portion was 0.1 mm. Next, a 2 μm polyester film (K100-2.0 W, manufactured by Mitsubishi Plastics, Inc.) was attached with a laminator at a linear pressure of 3 N / mm. This was cured at 40 ° C. for 2 days to obtain a dot adhesive film. Next, a foam layer was provided on the 2 μm polyester film of the dot adhesive film by the following method.

90 parts by mass of Sanyo Kasei's polyether polyol "GP-3000", 10 parts by mass of Sanyo Kasei's polyether polyol "GP-600", 0.1 part by mass of catalyst "Stanas Octoate" manufactured by Johoku Chemical Co., Ltd. 5 parts by mass of the foaming agent was mixed and stirred to prepare a mixture. Thereafter, the mixture and the MDI “Coronate 1130” manufactured by Nippon Polyurethane Co., Ltd. in a blending amount at which the isocyanate index was 1 were charged into a chamber provided in an Oaks mixer. At the same time, nitrogen gas was injected so that the density of the foam layer became 300 kg / m ³ .

Next, in the chamber, the above components were stirred to prepare a foamed gas-liquid mixture. Then, this gas-liquid mixture is supplied onto the 2 μm polyester film of the dot adhesive film sent at a speed of 5 m / min, and is peeled from the upper surface of the dripping gas-liquid mixture at the same speed as the dot adhesive film. The paper was supplied, the thickness was adjusted to 100 μm by a roll coater, and an uncured layer composed of a gas-liquid mixture was formed.

Thereafter, the laminate comprising the dot adhesive film, the uncured layer, and the release paper was placed in a 160 ° C. heating furnace with a far-infrared heater and heated for 1 minute. Next, the release paper was peeled from the laminate to obtain an adhesive tape in which the dot adhesive film and the foam layer were joined.

(Examples 2 to 13)
An adhesive tape was produced in the same manner as in Example 1, except that the shape and area of the adhesive portion (B) and the thickness of the adhesive portion (B) were changed to those shown in Tables 1 to 3.

(Example 14)
An adhesive tape was obtained in the same manner as in Example 1 except that the adhesive b was used instead of the adhesive a.

(Example 15)
An adhesive tape was obtained in the same manner as in Example 1 except that the adhesive c was used instead of the adhesive a.

(Example 16)
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1, except that pressure-sensitive adhesive d was used instead of pressure-sensitive adhesive a.

(Example 17)
An adhesive tape was obtained in the same manner as in Example 1, except that the adhesive e was used instead of the adhesive a.

(Example 18)
An adhesive tape was obtained in the same manner as in Example 1, except that the adhesive f was used instead of the adhesive a.

(Examples 19 to 25)
An adhesive tape was prepared in the same manner as in Example 1 except that the shape and area of the adhesive portion (B) and the thickness of the adhesive portion (B) were changed to those shown in Tables 4 and 5. The surface of the pressure-sensitive adhesive tape obtained in Example 20 having the substantially circular pressure-sensitive adhesive portion was observed at a magnification of 200 times using an optical microscope (FIG. 5).

(Example 26)
An adhesive tape was obtained in the same manner as in Example 1 except that the thickness of the foam layer was changed from 100 μm to 50 μm.

(Example 27)
An adhesive tape was obtained in the same manner as in Example 1, except that the density of the foam layer was changed from 300 kg / m ³ to 200 kg / m ³ .

(Example 28)
An adhesive tape was obtained in the same manner as in Example 1, except that the 2 μm polyester film was changed to a 25 μm polyester film.

(Example 29)
Instead of “PET50 × 1J0” (manufactured by Nipah Co., Ltd., a release liner having a silicone-based release-treated surface on the surface of a 50 μm polyester film), “PET25 × 1J0” (manufactured by Nipah Co., Ltd., on the surface of a 25 μm polyester film) An adhesive tape was obtained in the same manner as in Example 1 except that a release liner having a silicone-based release treated surface) was used.

(Example 30)
90 parts by mass of Sanyo Kasei's polyether polyol "GP-3000", 10 parts by mass of Sanyo Kasei's polyether polyol "GP-600", 0.1 part by mass of catalyst "Stanas Octoate" manufactured by Johoku Chemical Co., Ltd. 5 parts by mass of the foaming agent was mixed and stirred to prepare a mixture. Thereafter, the mixture and the MDI “Coronate 1130” manufactured by Nippon Polyurethane Co., Ltd. in a blending amount at which the isocyanate index was 1 were charged into a chamber provided in an Oaks mixer. At the same time, nitrogen gas was injected so that the density of the foam layer became 300 kg / m ³ .

  Next, in the chamber, the above components were stirred to prepare a foamed gas-liquid mixture. Then, the gas-liquid mixture is supplied onto a 25 μm polyester film “S10-25” manufactured by Toray Co., Ltd. which has been sent at a speed of 5 m / min. The release paper was supplied at the same speed as the film, and the thickness was adjusted to 100 μm by a roll coater to form an uncured layer composed of a gas-liquid mixture.

  Thereafter, the laminate comprising the polyester film, the uncured layer, and the release paper was placed in a 160 ° C. heating furnace with a far infrared heater and heated for 1 minute. Next, the release paper was peeled off from the laminate to obtain a bonded polyester film and foam layer.

  Next, the pressure-sensitive adhesive a was dot-printed on “PET50 × 1J0” (a release liner having a silicone-based release-treated surface on the surface of a 50 μm polyester film manufactured by Nipa Corporation) using a gravure coater. By drying for 1 minute, an approximately 2 μm thick island-shaped adhesive portion having a diamond shape as shown in FIG. 1 was obtained. In addition, the distance between an arbitrary adhesive portion and the adhesive portion adjacent to the arbitrary adhesive portion was 0.1 mm. Next, the polyester film and the foam layer were bonded to each other, and the polyester film layers were laminated and stuck at a linear pressure of 3 N / mm using a laminator. This was cured at 40 ° C. for 2 days to obtain a dot adhesive film.

(Comparative Example 1)
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 30, except that the pressure-sensitive adhesive layer was provided in an island shape using a gravure coater, but was provided on the entire surface using a roll coater.

(Measurement of gel fraction of adhesive part)
Each of the pressure-sensitive adhesives a to f was coated on the release-treated surface of a release liner and coated with the pressure-sensitive adhesive such that the thickness after drying was 50 μm, and dried in an environment of 100 ° C. for 3 minutes. Thereafter, the pressure-sensitive adhesive layer was formed by aging in a 40 ° C. environment for 2 days. A test piece was obtained by cutting the pressure-sensitive adhesive layer into a square having a length of 50 mm and a width of 50 mm.

After measuring the mass (G1) of the test piece, the test piece was immersed in toluene at 23 ° C. for 24 hours. After the immersion, a mixture of the test piece and toluene was filtered using a 300-mesh wire net to extract components insoluble in toluene. The mass (G2) of the insoluble component dried at 110 ° C. for one hour was measured.
The gel fraction was calculated based on the mass (G1), the mass (G2) and the following equation.
Gel fraction (% by mass) = (G2 / G1) × 100

(Measurement of dynamic viscoelasticity)
Each of the pressure-sensitive adhesives a to f was coated on the surface of the release liner so as to have a dry thickness of 50 μm, and dried to form a pressure-sensitive adhesive layer, which was then cured under an environment of 40 ° C. for 2 days. A test piece was obtained by stacking the cured adhesive layers until the total thickness became 2 mm.

Next, using a viscoelasticity tester (trade name: Ares 2KSTD, manufactured by Rheometrics Co., Ltd.), the test piece was sandwiched between parallel disk-shaped measuring portions having a diameter of 7.9 mm, and a frequency of 1 Hz and a heating time of 1 ° C./1. The storage elastic modulus (G ′) and the loss elastic modulus (G ″) from −50 ° C. to 150 ° C. were measured under the conditions of minutes. The loss tangent tan δ was calculated by the following formula.
Loss tangent tan δ = G ″ / G ′

(Measurement of total thickness of adhesive tape)
The layer thickness of the pressure-sensitive adhesive tape from which the release liner was peeled was measured using a thickness meter FFG-6 manufactured by Ozaki Seisakusho.

(Measurement of adhesive strength (1 hour after application))
The pressure-sensitive adhesive tape obtained in each of Examples and Comparative Examples was cut into a width of 20 mm, and the pressure-sensitive adhesive layer on one side was backed with a 25 μm-thick polyethylene terephthalate film to obtain a test piece. The backing was performed on the surface of the pressure-sensitive adhesive layer having a smooth surface, and was not performed on the pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive portion (B), which is a component of the present invention.

  The test piece was stuck on the surface of a clean and smooth stainless steel plate, and the upper surface thereof was pressurized by reciprocating a 2 kg roller once under a condition of 23 ° C. and 50% RH according to JISZ-0237. After leaving for 1 hour, the peel adhesion (peeling direction: 90 °, tensile speed: 0.3 m / min) was measured using a Tensilon tensile tester in an atmosphere of 23 ° C. and 50% RH. The measurement results are shown in the column of "Adhesive force (1 hour after application)" in the table.

(Measurement of holding force)
The pressure-sensitive adhesive tape obtained in each of Examples and Comparative Examples was cut into a width of 20 mm, and the pressure-sensitive adhesive layer on one side was lined with a 50-μm-thick aluminum foil to obtain a test piece. The backing was performed on the surface of the pressure-sensitive adhesive layer having a smooth surface, and was not performed on the pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive portion (B), which is a component of the present invention.

  The test piece was stuck on the surface of a clean and smooth stainless steel plate so as to have a stuck area of 20 mm x 20 mm, and the upper surface thereof was pressurized by reciprocating once using a 2 kg roller to JISZ-0237. In accordance with the above, the tape was left for 1 hour under the conditions of 23 ° C. and 50% RH, and then a 100 g load was applied in the shear direction in an atmosphere of 100 ° C., and the tape displacement distance after 24 hours was measured. The measurement results are shown in the column of "holding force" in the table.

(Evaluation of ease of bubble release)
The pressure-sensitive adhesive tape obtained in each of Examples and Comparative Examples was cut into a length of 50 mm and a width of 100 mm, and the release liner was peeled off. The aluminum plate was placed and left for 5 seconds under a load of 5 N from above the aluminum plate to obtain a temporary patch.

  Next, after reversing the temporary stuck material, a 2 kg roller was reciprocated once from the surface on the side of the adhesive tape to press them to obtain a laminate.

Ten laminates were produced by the above method. Whether or not air bubbles exist between the adhesive tape and the aluminum plate was confirmed by visually observing the swelling of the adhesive tape (10 mm ² or more). Based on the number of laminates for which the presence of air bubbles could not be confirmed by the above method, the ease with which the air bubbles were released was evaluated.

(Evaluation of unevenness of foam layer)
When the foamed layer of the obtained pressure-sensitive adhesive tape was observed under a fluorescent lamp from a position 30 cm from the upper surface of the pressure-sensitive adhesive tape, it was evaluated whether or not there was unevenness.
：: No unevenness〇: Slight unevenness X: Severe unevenness

(Appearance evaluation)
When the adhesive tape is attached to an aluminum plate and observed from a position 30 cm above the adhesive tape under a fluorescent lamp, it is determined whether or not the shape of the adhesive portion (above rhombus shape, approximately round shape, etc.) can be visually recognized. It was evaluated to the standard. Those in which the shape of the adhesive portion was not visually recognized at all were evaluated as “「 ”, those in which a part of the shape were slightly visible were evaluated as“ ○ ”, and those in which the shape was clearly visible were evaluated as“ x ”. did. In addition, as shown in Comparative Example 1, for the one in which the pressure-sensitive adhesive layer was formed by applying a pressure-sensitive adhesive to the entire surface of the foam base material, the pressure-sensitive adhesive portion did not form a predetermined shape, and thus the shape was changed to Since it could not be visually recognized by the method, it was evaluated as "-" without evaluation.

(Number of adhesive parts)
The number of the adhesive portions was determined by observing and counting an arbitrary range (a square having a flow direction of 5 cm and a width of 5 cm) or an area of the adhesive tape (a square having a flow direction of 1 cm and a width direction of 1 cm) with an electron microscope.

  The “substantially rhombus 1” in the table refers to a rhombus-shaped adhesive portion in which the angle of the corner facing the flow direction of the adhesive tape is 60 ° (the angle of the corner facing the width direction is 120 °) ( FIG. 1), “substantially rhombus 2” refers to a rhombus-shaped adhesive portion in which the angle of the corner facing the flow direction of the adhesive tape is 30 ° (the angle of the corner facing the width direction is 150 °). , "Substantially square shape" refers to a square-shaped adhesive portion in which the angle of the corner facing the flow direction of the adhesive tape is 90 ° (the angle of the corner facing the width direction is 90 °), and “substantially circular”. “Shape” refers to the adhesive portion having the shape shown in FIG. 2, “substantially hexagonal (hatched)” refers to the adhesive portion having the shape shown in FIG. 3, and “substantially square (hatched)” represents the adhesive portion having the shape shown in FIG. Point to.

  Since the pressure-sensitive adhesive tapes of the examples each have a plurality of independent pressure-sensitive adhesive layers on one surface, the pressure-sensitive adhesive tapes are excellent in the ease with which air bubbles can escape. Furthermore, although the pressure-sensitive adhesive tapes of the examples are thin, there is no unevenness of the foam layer, and the adhesive tapes and the holding power are excellent. On the other hand, in the pressure-sensitive adhesive tape of the comparative example, since the pressure-sensitive adhesive layer is provided not on the island but on the entire surface, there is no way for air bubbles to escape, and the ease of air bubbles is extremely poor.

DESCRIPTION OF SYMBOLS 1 Foam layer 2 Adhesive part 3 Adhesive tape 4 Graphite sheet 5 Single-sided adhesive tape 6 Double-sided adhesive tape 7 Release paper 11 Mixer for mixing foam raw material and gas 12 Roll coater 13 Heat treatment layer 20 Resin film (C) / or resin Film (C), adhesive portion (B) and release liner (D) integrated 21a Gas-liquid mixture 21b Uncured layer 30 Laminate

Claims (9)

An adhesive tape having two or more adhesive portions (B) on the foam layer (A), the resin film layer (C), and the resin film (C) side, wherein between the two or more adhesive portions (B) There is a region having no adhesive portion (B), and the region communicates with an end of the adhesive tape,
The shape of the adhesive portion (B) when observing the adhesive portion (B) from one surface (a) side of the foam layer (A) is a substantially circular shape, a substantially square shape, or a substantially hexagonal shape. ,
In the range of 5 cm in the flow direction and 5 cm in the width direction of the adhesive tape, 10 to 50,000 of the adhesive portions (B) are present,
Wherein Ri -30 ° C. to 20 ° C. der peak temperature of the loss tangent based on dynamic viscoelasticity spectrum measured at a frequency 1Hz adhesive portion (B),
A pressure-sensitive adhesive tape , wherein a ratio of a region having the pressure-sensitive adhesive portion (B) to an area of one surface (a) of the foam layer (A) is 10% to 99% . The pressure-sensitive adhesive tape according to claim 1, wherein a load when compressed by 50% is 0.003 MPa to 1 MPa. The pressure-sensitive adhesive tape according to claim 1, wherein the thickness of the resin film layer (C) is 1 to 25 μm. The pressure-sensitive adhesive tape according to any one of claims 1 to 3, having a release liner (D) on a surface in contact with the pressure-sensitive adhesive portion (B). The distance between an arbitrary adhesive portion (b1) selected from the two or more adhesive portions (B) and the adhesive portion (b2) close to the adhesive portion (b1) is 0.5 mm or less. The pressure-sensitive adhesive tape according to any one of items 4 to 5 . The pressure-sensitive adhesive tape according to any one of claims 1 to 5 , wherein the foam layer (A) is a polyurethane foam layer or an acrylic foam layer. A smooth stainless steel plate is placed on the surface having the adhesive portion (B), and the two plates are reciprocated once using a 2 kg roller to press them together and left at 23 ° C. and 50% RH for 1 hour. The pressure-sensitive adhesive tape according to any one of claims 1 to 6 , wherein a 180 ° peel adhesive force measured by using the test piece is in a range of 2 N / 20 mm to 12 N / 20 mm. Claim resin film layer (C) and the adhesive section (B) and release liner (D) is on the resin film layer (C) but is integral, formed by coating the foam layer (A) 1 to 7 3. The method for producing an adhesive tape according to item 1. A display device comprising the adhesive tape according to claim 1 provided on a non-display surface side of a display.

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