CN113980612A

CN113980612A - Adhesive tape and method for producing same

Info

Publication number: CN113980612A
Application number: CN202111285588.6A
Authority: CN
Inventors: 山上晃; 今井克明
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 2016-12-20
Filing date: 2017-12-07
Publication date: 2022-01-28
Also published as: CN110072957A; JPWO2018116845A1; KR20190099202A; WO2018116845A1; CN110072957B; KR102377927B1; KR20220038544A; JP6624480B2; KR102510749B1; CN113980613A

Abstract

The present invention addresses the problem of providing a pressure-sensitive adhesive tape that can rapidly remove air bubbles from the interface between the pressure-sensitive adhesive tape and an adherend to prevent air bubbles from remaining at the interface, and that has excellent adhesiveness and cushioning properties, is low in cost, and is thin. The present invention relates to an adhesive tape having a foam layer (A), a resin film layer (C), and 2 or more adhesive parts (B) on the resin film (C) side, wherein a region having no adhesive part (B) is present between the 2 or more adhesive parts (B), and the region passes through an end of the adhesive tape, and a method for manufacturing the adhesive tape.

Description

Adhesive tape and method for producing same

The present application is a divisional application of an application having an application date of 2017, 12 and 7 months, an application number of 201780076844.6, and an invention name of "adhesive tape and method for manufacturing the same".

Technical Field

The present invention relates to an adhesive tape having a foam layer, which can be used in, for example, a manufacturing place of electronic equipment.

Background

Adhesive tapes are widely used in, for example, production fields of electronic devices such as OA devices and home electric appliances because of their excellent workability and high adhesion reliability.

In recent years, electronic devices, particularly portable electronic terminals such as personal computers, digital video cameras, electronic books, cellular phones, PHS's, smart phones, game devices, and electronic books, are required to be downsized and thinned, and along with this, adhesive tapes and the like constituting the portable electronic terminals are also required to be thinned.

In general, in the display device as described above, an adhesive tape having a foam layer having cushioning properties is often attached to the back surface of the display in order to prevent cracking and waviness (a phenomenon of fluctuation in the depth of liquid crystal) of the display (patent document 1).

However, since the pressure-sensitive adhesive tape having a foamed layer is very flexible, bubbles are often involved in the tape during the application of the pressure-sensitive adhesive tape, and wrinkles often appear. In particular, when the lamination is performed after several minutes after the alignment by a punch at the time of the attachment, the above-described problem is remarkably generated.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2004-309699

Disclosure of Invention

Problems to be solved by the invention

The present invention addresses the problem of providing a low-cost and thin pressure-sensitive adhesive tape that can rapidly remove air bubbles from the interface between the pressure-sensitive adhesive tape and an adherend to prevent air bubbles from remaining at the interface, and that has excellent adhesiveness and cushioning properties.

Means for solving the problems

The present inventors have solved the above-described problems by an adhesive tape comprising a foam layer (a), a resin film layer (C), and 2 or more adhesive portions (B) on the resin film (C) side, wherein a region having no adhesive portion (B) is present between the 2 or more adhesive portions (B), and the region is open to an end of the adhesive tape.

Effects of the invention

The pressure-sensitive adhesive tape of the present invention rapidly releases bubbles from the interface with an adherend, hardly causes bubbles to remain at the interface, and is excellent in cushioning properties and adhesive strength even when it is thin. Therefore, the adhesive tape of the present invention can prevent cracking, waviness of a display without lowering the production efficiency of a final product or its parts. Therefore, the adhesive tape of the present invention can be suitably used for, for example, adhesion to a non-display surface side of a display device.

Drawings

Fig. 1 is a plan view of an adhesive tape having substantially rhombic adhesive portions, as viewed from the adhesive portion side of the adhesive tape.

Fig. 2 is a plan view of the pressure-sensitive adhesive tape having a substantially circular pressure-sensitive adhesive portion as viewed from the pressure-sensitive adhesive portion side of the pressure-sensitive adhesive tape.

Fig. 3 is a plan view of the adhesive tape having the substantially hexagonal adhesive portion as viewed from the adhesive portion side of the adhesive tape.

Fig. 4 is a plan view of the pressure-sensitive adhesive tape having a substantially quadrangular pressure-sensitive adhesive portion as viewed from the pressure-sensitive adhesive portion side of the pressure-sensitive adhesive tape.

Fig. 5 is a plan view of the surface having the pressure-sensitive adhesive portion of the pressure-sensitive adhesive tape obtained in example 20.

Fig. 6 is a schematic view showing a method for producing a polyurethane foam laminate of the present invention.

Detailed Description

(adhesive tape)

The adhesive tape of the present invention is an adhesive tape having a foam layer (a), a resin film layer (C), and 2 or more adhesive portions (B) on the resin film (C) side, wherein a region having no adhesive portion (B) is present between the 2 or more adhesive portions (B), and the region passes through an end portion of the adhesive tape.

Specific embodiments of the adhesive tape of the present invention include: a single-sided pressure-sensitive adhesive tape having a foam layer (A), a resin film layer (C), and 2 or more pressure-sensitive adhesive sections (B) on the resin film (C) side; further, the double-sided pressure-sensitive adhesive tape has a pressure-sensitive adhesive layer on the foam layer (A) side. 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 2 or more adhesive portions (B), there are regions where no component constituting the adhesive portion (B) is present, or regions where the component constituting the adhesive portion (B) may be present to such an extent that adhesiveness is not exerted. Therefore, when the adhesive tape of the present invention is viewed from the side surface direction, it can be observed that: the adhesive part (B) is formed in a convex shape on the surface of the resin film (C).

The adhesive tape of the present invention has the following configuration: the region between the 2 or more adhesive portions (B) having no adhesive portion (B) is open to a part of the end portion (outer edge portion) of the adhesive tape. By using the pressure-sensitive adhesive tape having the above-described configuration, when the pressure-sensitive adhesive tape is attached to an adherend, bubbles are released to the outside from the interface between the pressure-sensitive adhesive tape and the adherend through the region, and therefore, appearance defects due to expansion or the like of the pressure-sensitive adhesive tape can be prevented, and excellent cushioning properties, adhesive strength, and the like can be maintained.

The adhesive tape of the present invention is preferably an adhesive tape having a total thickness of 300 μm or less, more preferably an adhesive tape having a thickness of 30 to 250 μm, still more preferably an adhesive tape having a thickness of 50 to 200 μm, and particularly preferably an adhesive tape having a thickness of 50 to 100 μm, for example, from the viewpoint of contributing to the reduction in thickness of a portable electronic terminal or the like. The total thickness of the adhesive tape is a thickness of the adhesive tape measured by a method using a dial gauge according to JIS K6250 under conditions that the contact surface of the dial gauge is a flat surface, the diameter thereof is 8mm, and the load is 0.51N, excluding the thickness of the release liner. The thickness can be measured by, for example, a thickness meter FFG-6 manufactured by Kawasaki corporation.

The pressure-sensitive adhesive tape of the present invention is preferably a pressure-sensitive adhesive tape having an adhesive strength of 1N/20mm to 12N/20mm, more preferably a pressure-sensitive adhesive tape having an adhesive strength of 1.5N/20mm to 10N/20mm, and is preferably a pressure-sensitive adhesive tape having an adhesive strength of 3N/20mm to 8N/20mm, from the viewpoint of obtaining a pressure-sensitive adhesive tape which is thin, easily removes air bubbles from the interface between an adherend and the pressure-sensitive adhesive tape even when holes or the like are not provided in a part thereof, and has excellent adhesive strength. On the other hand, when more excellent adhesiveness is required, the adhesive tape is more preferably an adhesive tape having an adhesive strength of 4N/20mm to 10N/20mm, and more preferably an adhesive tape having an adhesive strength of 4.5N/20mm to 8N/20 mm.

The adhesion is a value measured according to JISZ 0237. Specifically, the adhesion is a value measured as follows: the surface of the pressure-sensitive adhesive tape having the pressure-sensitive adhesive part (B) was overlaid on a clean and smooth stainless steel plate (BA plate), and the pressure was applied thereto by reciprocating 1 time thereon using a 2kg roller, and the obtained object was left at 23 ℃ and 50% RH for 1 hour, and then the pressure-sensitive adhesive tape was peeled off at a speed of 0.3m/min in the 180 ° direction, thereby obtaining a value.

The pressure-sensitive adhesive tape of the present invention is preferably a pressure-sensitive adhesive tape having a holding force of 2mm or less, more preferably a pressure-sensitive adhesive tape having a holding force of 0.5mm or less, and still more preferably a pressure-sensitive adhesive tape having a holding force of 0.1mm or less, because peeling, separation of components, and the like of an adherend and a foam layer (a) due to repulsive force and the like can be prevented even when the pressure-sensitive adhesive tape is thin, and particularly, the peeling can be prevented even when the pressure-sensitive adhesive tape is used at a relatively high temperature.

The holding force is a value measured according to jis z 0237. Specifically, the above-mentioned holding force is a value measured as follows: the surface of the pressure-sensitive adhesive tape having the pressure-sensitive adhesive part (B) was overlaid on a clean and smooth stainless steel plate (hair line), and the pressure was applied by reciprocating 1 time thereon using a 2kg roller, and the resultant was left to stand at 23 ℃ and 50% RH for 1 hour to prepare a test piece; next, the stainless steel plate constituting the test piece was fixed in the vertical direction in an environment of 100 ℃, a load of 100g was applied to the lower end portion of the pressure-sensitive adhesive tape constituting the test piece, the test piece was left for 24 hours in this state, and then the offset distance between the stainless steel plate and the pressure-sensitive adhesive tape was measured by a vernier caliper to obtain a value.

(adhesive part B)

First, the pressure-sensitive adhesive part (B) constituting the pressure-sensitive adhesive tape of the present invention will be described.

The adhesive portion (B) is provided directly on the resin film (C) or on the resin film (C) with another layer interposed therebetween. The 2 or more adhesive portions (B) may have a region where no component constituting the adhesive portion (B) is present or a region where the component constituting the adhesive portion (B) may be present to such an extent that adhesiveness is not exerted.

The thickness of the adhesive part (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.

Further, the apparatus has the following configuration: the region between the 2 or more adhesive portions (B) having no adhesive portion (B) is open to a part of the end portion (outer edge portion) of the adhesive tape. By using the pressure-sensitive adhesive tape having the above-described configuration, even when a hole or the like is not provided in a part of the pressure-sensitive adhesive tape, bubbles can be easily removed from the interface when the pressure-sensitive adhesive tape is attached to an adherend, and therefore, it is possible to prevent appearance defects caused by expansion or the like of the pressure-sensitive adhesive tape and maintain excellent thermal conductivity (heat dissipation property), adhesion, and the like.

The shape of the pressure-sensitive adhesive part (B) is preferably a substantially quadrangular shape, a substantially hexagonal shape, a substantially circular shape or the like when the pressure-sensitive adhesive tape of the present invention is viewed from the side of the one surface (a) of the resin film (C), and is preferably a substantially circular shape because bubbles (air release property) can be easily released from the interface between the pressure-sensitive adhesive tape and the adherend and a good adhesive force can be maintained.

The substantially circular shape is not particularly limited, and the ratio [ maximum diameter/minimum diameter ] of the maximum diameter to the minimum diameter of any 1 adhesive part is preferably 1 to 4. More preferably 1 to 2, and most preferably 1 to 1.5. As an example of the substantially circular shape, a shape as shown in fig. 5 can be cited. The adhesive portions having the above shapes are basically independent from each other, but may be a portion in which 2 or more adhesive portions are partially connected as shown in fig. 5.

The above-mentioned substantially quadrangular shape includes a substantially square shape, a substantially rectangular shape, a substantially trapezoidal shape, a substantially rhombic shape, and the like, and in the case of a substantially rhombic shape, bubbles are easily removed from the interface with the adherend (air release property) and a good adhesive force can be maintained, which is preferable.

The term "substantially" such as substantially quadrangular and substantially hexagonal means including the following shapes: for example, when a release liner or the like is attached to the surface of the adhesive part (B) or when the adhesive tape is wound into a roll, the adhesive part (B) is pressed, and the corners of the quadrangle and the hexagon are rounded, and the straight line part is curved.

Among the substantially quadrangular corners, a substantially rhombic shape in which the angle of the corner facing the flow direction of the pressure-sensitive adhesive tape is less than 90 ° is preferable, and in the range of 45 ° to 70 °, bubbles are easily removed from the interface with the adherend (air release property) and a good adhesive force can be maintained, which is more preferable.

In addition, it is preferable that any of the adhesive part (B1) and the adhesive part (B2) constituting the 2 or more adhesive parts (B) does not align with the flow direction and the width direction of the pressure-sensitive adhesive tape.

In many cases, the adhesive tape is cut into an arbitrary shape depending on the application. In this case, by arranging the adhesive part (B1) and the adhesive part (B2) so as not to oppose the flow direction and the width direction, when the adhesive tape is cut at an arbitrary position, the adhesive part (B) is present in a part of the end part thereof, and therefore, the peeling of the adhesive tape can be suppressed.

Further, the ratio of the major axis of the contact region (r2) between the pressure-sensitive adhesive section (b1) and the release liner attached to the surface thereof, measured by the above method, to the major axis of the contact region (r1) between the pressure-sensitive adhesive section (b1) and the support [ major axis of the contact region (r 2)/major axis of the contact region (r1) ] x 100 is preferably 97% to 110%, and in the range of 97% to 105%, it is more preferable from the viewpoint of compatibility between ease of removal of bubbles from the interface between the pressure-sensitive adhesive tape and the adherend and more excellent adhesiveness.

The pressure-sensitive adhesive tape of the present invention is preferably a pressure-sensitive adhesive tape in which the ratio of the pressure-sensitive adhesive part (b1) satisfying the requirement of the above ratio [ contact area (s 2)/contact area (s1) ] x 100, among all the pressure-sensitive adhesive parts provided on the surface of the support, is 50% to 100%, more preferably 80% to 100%, still more preferably 90% to 100%, and particularly preferably 95% to 100%, from the viewpoint of maximally exerting the effect of the present invention.

A distance between any of the adhesive parts (B1) selected from the 2 or more adhesive parts (B) and the adhesive part (B2) close to the adhesive part (B1) is preferably 0.5mm or less, more preferably 0.05mm to 0.2mm, even more preferably 0.06mm to 0.15mm, and is 0.08mm to 0.13mm, and even when a hole or the like is not provided in a part of the pressure-sensitive adhesive tape, bubbles are easily released from the interface between the pressure-sensitive adhesive tape and the adherend (gas release property) and a good adhesive force can be maintained, which is particularly preferable.

The area is preferably 0.001mm per 1 arbitrary bonded part (B1) selected from the above bonded parts (B)²～100mm²More preferably 0.01mm²～25mm²More preferably 0.015mm²～16mm²0.02mm in diameter²～5mm²In the case of the pressure-sensitive adhesive tape, even when a hole or the like is not provided in a part of the pressure-sensitive adhesive tape, bubbles are easily released from the interface between the pressure-sensitive adhesive tape and the adherend (gas releasing property), and a good adhesive force can be maintained, which is particularly preferable.

The pressure-sensitive adhesive part (B) is preferably 10 to 1000000, more preferably 1000 to 50000, and 5000 to 40000 in the range of the area (square having a flow direction of 5cm and a width direction of 5 cm) of the pressure-sensitive adhesive tape of the present invention, and is particularly preferable because bubbles (gas releasing property) are easily released from the interface between the pressure-sensitive adhesive tape and the adherend even when a hole or the like is not provided in a part of the pressure-sensitive adhesive tape, and a good adhesive strength can be maintained.

In addition, as the pressure-sensitive adhesive tape, from the viewpoint of facilitating the release of bubbles from the interface between the pressure-sensitive adhesive tape and an adherend (gas release property) at the time of attachment, maintaining good adhesive strength, and effectively preventing appearance defects due to the shape of the pressure-sensitive adhesive portion even when the adherend such as a graphite sheet is further thinned, it is preferable to use a pressure-sensitive adhesive tape having 120 to 2000 pressure-sensitive adhesive portions in a range of a predetermined area (a square having a flow direction of 1cm and a width direction of 1 cm) of the pressure-sensitive adhesive tape, more preferably a pressure-sensitive adhesive tape having 280 to 1600 pressure-sensitive adhesive portions, and still more preferably a pressure-sensitive adhesive tape having 520 to 1200 pressure-sensitive adhesive portions.

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

The ratio of the region having the adhesive portion (B) to the area of the one surface (a) is preferably 10% to 99%. More preferably 20% to 90%, still more preferably 30% to 80%, and most preferably 35% to 80%. In the case where the amount of the gas is within the above range, a substantially circular pressure-sensitive adhesive portion described later can be formed, and as a result, a pressure-sensitive adhesive tape which can easily release bubbles from the interface between the pressure-sensitive adhesive tape and an adherend (gas release property) and can maintain good adhesion can be produced with good efficiency, and thus, the pressure-sensitive adhesive tape is particularly preferable. The ratio of the region is the ratio of the area of the pressure-sensitive adhesive portion (B) in the area of the square pressure-sensitive adhesive tape having a flow direction of 5cm and a width direction of 5 cm.

The peak temperature of the loss tangent of the pressure-sensitive adhesive part (B) based on the dynamic viscoelasticity spectrum measured at a frequency of 1Hz is not particularly limited, but is preferably-30 to 20 ℃, more preferably-20 to 10 ℃, and in the case of-10 to 5 ℃, bubbles are easily released from the interface with the adherend (air release property) and good adhesive strength can be maintained, and as a result, appearance defects due to expansion and the like of the pressure-sensitive adhesive tape and a decrease in performance such as thermal conductivity (heat release property), heat resistance, adhesive strength and the like can be more effectively prevented, and therefore, the pressure-sensitive adhesive part (B) is more preferable.

For the dynamic viscoelasticity measurement, a viscoelasticity tester (trade name: ARES2KSTD, manufactured by Rheometrics) was used, and a test piece was sandwiched between parallel disks as a measurement portion of the tester to measure a storage elastic modulus (G ') and a loss elastic modulus (G') at a frequency of 1 Hz. The loss tangent is calculated from the formula (tan δ ═ G ")/(G'). The above peak temperature means a peak temperature confirmed in a spectrum of tan. delta. for a measurement temperature region (-50 ℃ to 150 ℃).

As the test piece, an adhesive layer having a thickness of 0.5mm to 2.5mm formed by using the adhesive used for forming the adhesive part (B) can be used.

In addition, as the test piece, a test piece in which a total thickness of the pressure-sensitive adhesive layers is 0.5mm to 2.5mm in a test piece in which a plurality of pressure-sensitive adhesive tapes of the present invention are laminated can be used. In the case of using the test pieces having different structures, the peak temperature does not substantially change when the total thickness of the pressure-sensitive adhesive layer (B) in the test pieces is the same, although the value of tan δ changes. Therefore, any test piece can be used for the measurement of the peak temperature.

The pressure-sensitive adhesive section (B) is preferably a pressure-sensitive adhesive section having a gel fraction of 10 to 60 mass%, more preferably a pressure-sensitive adhesive section having a gel fraction of 20 to 55 mass%, and when a pressure-sensitive adhesive section having a gel fraction of 30 to 50 mass% is used, the surface shape of the pressure-sensitive adhesive section (B) is easily maintained even when it is thin, and therefore, changes with time are easily prevented, and bubbles can be easily removed from the interface between the adherend and the pressure-sensitive adhesive section (B), and as a result, appearance defects due to expansion and the like of the pressure-sensitive adhesive tape, and reductions in performance such as thermal conductivity (heat dissipation), heat resistance, and adhesive strength can be more effectively prevented, and therefore, the pressure-sensitive adhesive tape is more preferably used. The gel fraction is a value measured by the following method.

The gel fraction is a value measured by the following method.

(1) The adhesive was applied to the release-treated surface of the release liner (D) so that the thickness after drying became 50 μm, and the resultant was dried at 100 ℃ for 3 minutes and then cured at 40 ℃ for 2 days to form an adhesive layer.

(2) The adhesive layer was cut into a square having a length of 50mm and a width of 50mm to prepare a test piece.

(3) The mass of the test piece (G1) was measured, and then the test piece was immersed in toluene at 23 ℃ for 24 hours.

(4) After the immersion, the mixture of the test piece and toluene was filtered using a 300-mesh metal net, and insoluble components in toluene were extracted. The insoluble matter was dried at 110 ℃ for 1 hour, and the mass of the resulting substance was measured (G2).

(5) The gel fraction was calculated based on the mass (G1), the mass (G2) and the following formula.

Gel fraction (% by mass) of (G2/G1). times.100

The pressure-sensitive adhesive part (B) is preferably a pressure-sensitive adhesive part having a thickness of 1 to 6 μm, and when a pressure-sensitive adhesive part having a thickness of 2 to 5 μm is used, bubbles can be easily removed from the interface between the adherend and the pressure-sensitive adhesive part (B), and as a result, appearance defects due to swelling of the pressure-sensitive adhesive tape and deterioration in performance such as thermal conductivity, heat resistance, and adhesive strength can be more effectively prevented, and therefore, the pressure-sensitive adhesive part (B) is more preferably used. The thickness of the adhesive part (B) is the thickness of the double-sided adhesive tape measured by a method using a dial gauge according to JIS K6783 under the conditions that the contact surface of the dial gauge is a flat surface, the diameter thereof is 5mm, and the load is 1.23N.

The adhesive part (B) can be formed using a known adhesive such as 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, a polyamide adhesive, a fluorine adhesive, a creep property improving adhesive, or a radiation curing adhesive. Among these, the adhesive part (B) is preferably used because it is excellent in adhesion reliability when an acrylic adhesive is used.

When the pressure-sensitive adhesive tape of the present invention is used as the pressure-sensitive adhesive tape having the pressure-sensitive adhesive parts or the pressure-sensitive adhesive layers on both sides of the foam layer, the pressure-sensitive adhesive parts or the pressure-sensitive adhesive layers may have the same composition and the same gel fraction, or may have different compositions and different gel fractions.

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

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

As the alkyl (meth) acrylate, for example, 2 or more of the following may be used alone or in combination: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-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, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, dodecyl (meth) acrylate, and the like, Cetyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like. Among these, the alkyl (meth) acrylate is preferably an alkyl (meth) acrylate in which the alkyl group has 1 to 20 carbon atoms, and more preferably an alkyl (meth) acrylate in which the alkyl group has 4 to 18 carbon atoms. Examples of the alkyl group include a linear or branched alkyl group.

The pressure-sensitive adhesive tape is preferably one in which butyl (meth) acrylate is used as the alkyl (meth) acrylate having an alkyl group of 4 to 18 carbon atoms, because the pressure-sensitive adhesive layer (B) is easily maintained in its surface shape, and therefore changes with time are easily prevented, and bubbles are easily removed from the interface with an adherend (air release property) and good adhesion can be maintained.

As the (meth) acrylic monomer, in addition to the above, two or more of the following may be used alone or in combination: carboxyl group-containing monomers such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid, and anhydrides thereof; sulfonic acid group-containing monomers such as sodium vinylsulfonate; monomers having a cyano group such as acrylonitrile; amide group-containing monomers such as acrylamide, methacrylamide, N-vinylpyrrolidone and N, N-dimethyl (meth) acrylamide; hydroxyl group-containing monomers such as hydroxyalkyl (meth) acrylate and glycerol dimethacrylate; amino group-containing monomers such as aminoethyl (meth) acrylate and (meth) acryloylmorpholine; imide group-containing monomers such as cyclohexylmaleimide and isopropylmaleimide; monomers having an epoxy group such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; examples of the monomer include a 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, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and divinylbenzene.

As the monomer, in addition to the (meth) acrylic monomer, an aromatic vinyl compound such as styrene or substituted styrene; olefins such as ethylene, propylene and butadiene; vinyl esters such as vinyl acetate; vinyl chloride, and the like.

The acrylic polymer can be produced by polymerizing the monomers by a method such as solution polymerization, bulk polymerization, suspension polymerization, or emulsion polymerization, and the solution polymerization is preferably used from the viewpoint of improving the production efficiency of the acrylic polymer.

The solution polymerization method includes, for example, a method of mixing and stirring the monomer, the polymerization initiator, and the organic solvent at a temperature preferably ranging from 40 ℃ to 90 ℃ to perform radical polymerization.

As the polymerization initiator, for example, peroxides such as benzoyl peroxide and lauroyl peroxide; azo thermal polymerization initiators such as azobisisobutyronitrile; acetophenone-based photopolymerization initiator, benzoin ether-based photopolymerization initiator, benzoin ketal-based photopolymerization initiator, acylphosphine oxide-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzophenone-based photopolymerization initiator, and the like.

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

The acrylic polymer obtained by the above method is preferably an acrylic polymer having a weight average molecular weight of 30 to 120 ten thousand, more preferably an acrylic polymer having a weight average molecular weight of 40 to 110 ten thousand, and is preferably an acrylic polymer having a weight average molecular weight of 50 to 100 ten thousand, from the viewpoint of obtaining a pressure-sensitive adhesive tape having more excellent adhesive strength and ease of removal of bubbles even when the pressure-sensitive adhesive tape is thin.

The weight average molecular weight is a value calculated by measuring by gel permeation chromatography (GPC method) and converting into standard polystyrene. Specifically, the weight average molecular weight can be measured under the following conditions using a GPC apparatus (HLC-8329GPC) manufactured by Tosoh corporation.

Sample concentration: 0.5% by mass (tetrahydrofuran solution)

Sample injection amount: 100 μ l

Eluent: tetrahydrofuran (THF)

Flow rate: 1.0 ml/min

Measuring temperature: 40 deg.C

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

Protection of the column: TSKgel HXL-H

A detector: differential refractometer

Weight average molecular weight of standard polystyrene: 1 to 2000 thousands (made by Tosoh corporation)

As the adhesive that can be used for forming the adhesive part (B), an adhesive containing a tackifier resin is preferably used in terms of forming an adhesive part having more excellent adhesive strength, tensile strength, and tensile breaking strength.

Examples of the tackifier resin include petroleum resin-based tackifier resins such as rosin-based tackifier resin, polymerized rosin ester-based tackifier resin, rosin phenol-based tackifier resin, stabilized rosin ester-based tackifier resin, disproportionated rosin ester-based tackifier resin, hydrogenated rosin ester-based tackifier resin, terpene-phenol-based tackifier resin, and styrene-based tackifier resin.

As the above-mentioned tackifier resin, it is preferable to use a rosin-based tackifier resin and a petroleum-based tackifier resin in combination from the viewpoint of obtaining a pressure-sensitive adhesive tape having more excellent adhesive strength and ease of removing bubbles even when the pressure-sensitive adhesive tape is thin. The rosin-based tackifier resin and the petroleum-based tackifier resin are particularly preferably used in combination with the acrylic polymer, and from the viewpoint of obtaining a pressure-sensitive adhesive tape having more excellent adhesive strength and ease of removal of bubbles even when the pressure-sensitive adhesive tape is thin, the rosin-based tackifier resin and the petroleum-based tackifier resin are preferably used in combination with an acrylic polymer obtained by polymerizing a monomer containing butyl (meth) acrylate.

In addition, as the tackifier resin, a tackifier resin which is liquid at normal temperature is preferably used in order to further improve the initial adhesive strength of the adhesive part (B). Examples of the tackifier resin which is liquid at room temperature include processing oils, polyester plasticizers, low molecular weight liquid rubbers such as polybutene, terpene-phenol resins, and commercially available YP-90L manufactured by YASUHARA CHEMICAL.

The tackifier resin is preferably used in a range of 20 to 60 parts by mass with respect to 100 parts by mass of the acrylic polymer, and more preferably in a range of 30 to 55 parts by mass in order to obtain a pressure-sensitive adhesive tape having further excellent adhesive strength.

As the binder forming the pressure-sensitive adhesive part (B), a binder containing a softening agent, a plasticizer, a filler, an antioxidant, a colorant, and the like, as necessary, in addition to the acrylic polymer and the like, can be used.

Among these, when a crosslinking agent is used, the gel fraction of the pressure-sensitive adhesive part (B) can be adjusted to an appropriate range, and as a result, the shape of the pressure-sensitive adhesive part (B) is easily maintained, and therefore, changes over time are easily prevented, bubbles can be easily removed from the interface between an adherend and the pressure-sensitive adhesive layer (B), and a pressure-sensitive adhesive tape having excellent adhesive strength can be obtained, which is preferable.

As the crosslinking agent, for example, an isocyanate crosslinking agent or an epoxy crosslinking agent is preferably used.

Examples of the isocyanate crosslinking agent include tolylene diisocyanate, naphthalene-1, 5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, trimethylolpropane-modified tolylene diisocyanate, and the like, and tolylene diisocyanate adducts such as tolylene diisocyanate and trimethylolpropane-modified tolylene diisocyanate are preferably used. The tolylene diisocyanate adduct is a substance having a structure derived from tolylene diisocyanate in the molecule, and examples of commercially available products include CORONATE L (manufactured by Nippon polyurethane industries Co., Ltd.).

When the isocyanate crosslinking agent is used, an acrylic polymer having a hydroxyl group is preferably used as the acrylic polymer. The acrylic polymer having a hydroxyl group may be produced using, for example, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and the like, as monomers used for producing the acrylic polymer, and 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are more preferably used.

Further, as the epoxy crosslinking agent, for example, TETRAD X and TETRAD C available from Mitsubishi gas chemical, E-05X available from Mitsubishi chemical, and the like can be used.

When the epoxy crosslinking agent is used, an acrylic polymer having an acid group is preferably used as the acrylic polymer. As the monomer used for producing the acrylic polymer having an acid group, for example, (meth) acrylic acid, acrylic acid dimer, itaconic acid, crotonic acid, maleic anhydride, and the like are preferably used, and (meth) acrylic acid is more preferably used.

As the adhesive that can be used for forming the adhesive part (B), an adhesive containing a solvent as necessary is preferably used. The adhesive is preferably an adhesive whose viscosity is adjusted to a range of 0.1 to 1000 mPas, more preferably an adhesive whose viscosity is adjusted to a range of 1 to 200 mPas, and even more preferably an adhesive whose viscosity is adjusted to a range of 10 to 100 mPas, since the adhesive portion (B) having a predetermined shape is easily formed.

(resin film layer (C))

Next, the resin film layer (C) constituting the 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, polyethylene terephthalate films having excellent heat resistance and strength and low cost are most preferable.

The thickness of the resin film layer (C) is preferably 1 to 100 μm. More preferably 1.5 to 50 μm, and 1.5 to 6 μm, the cushion is thin and does not deteriorate, so that the cushion is preferable.

(Release liner (D))

The pressure-sensitive adhesive tape of the present invention may have a release liner (D) on the surface contacting the pressure-sensitive adhesive part (B).

The release liner (D) is a liner 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, the polyethylene terephthalate film is preferable because it has 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 the amount is within the above range, the foam layer (a) is preferably formed because the foam layer is less likely to be uneven.

The release agent is not particularly limited, and a silicone release agent is preferable because the release force can be easily adjusted.

(foam layer (A))

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

The foam layer (A) is preferably a foam layer having a 50% compressive strength of 0.003MPa to 1MPa, more preferably a foam layer having a 50% compressive strength of 0.01MPa to 0.5MPa, and still more preferably a foam layer having a 50% compressive strength of 0.02MPa to 0.4 MPa. When the foam layer in the above range is used, it is particularly preferable from the viewpoint of obtaining a pressure-sensitive adhesive tape having cushioning properties and suitable conformability to an adherend.

As the foam layer (a), for example, a sheet-shaped foam layer formed of a foamed resin may be used, a foam layer in which the foam layer (a) is applied to the resin film (C) may be used, or a foam layer in which the foam layer (a) is applied to an object in which the resin film (C), the adhesive portion (B), and the release liner (D) are integrated may be used. Among these, when a foam layer in which the foam layer (a) is coated on an object in which the resin film (C), the adhesive portion (B), and the release liner (D) are integrated is used, a thin and flexible foam layer is easily formed, and is particularly preferable.

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

The polyurethane foam layer can be obtained as follows: the resin film is obtained by mixing a raw material containing a polyisocyanate and a polyol with a gas to produce a gas-liquid mixture, supplying the gas-liquid mixture onto a resin film, and then heating the gas-liquid mixture to react the raw material.

The raw material for the polyurethane foam layer is a composition containing a polyisocyanate and a polyol, and the following other components are contained as necessary.

The polyisocyanate is not particularly limited, and a polyisocyanate conventionally used for producing a polyurethane foam can be used. As the polyisocyanate, 4' -diphenylmethane diisocyanate, tolylene diisocyanate, and the like are generally used. In addition to these, aromatic or aliphatic polyisocyanates such as 1, 6-hexamethylene diisocyanate, 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 4' -dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and prepolymer type polyisocyanates can be used. The polyisocyanate may be used in combination of 2 or more, or may be used alone of 1.

The polyisocyanate is compounded 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 polyols conventionally used for producing polyurethane foams can be used. Specifically, polyether polyols, polyester polyols, and polyether polyols which are copolymers of polyether polyols and polyester polyols can be used. In addition, a polymer polyol may be used in combination in order to improve the tensile strength. The polymer polyol is, for example, a polyol obtained by graft polymerizing an ethylenically unsaturated compound such as acrylonitrile, styrene, or methyl methacrylate on a polyether polyol in a solid content of preferably 5 to 40% by mass, more preferably 10 to 30% by mass.

The average molecular weight of the polyol is preferably 300 to 6000, and more preferably 900 to 4000. The above-mentioned polyhydric alcohols may be used in 1 kind, or 2 or more kinds may be used in combination.

The raw materials for the polyurethane foam layer other than the above include a catalyst, a foam stabilizer, a crosslinking agent, and the like.

Examples of the catalyst include organic tin compounds such as tin octylate, dibutyltin diacetate and dibutyltin dilaurate; organic zinc compounds such as zinc octylate; organic nickel compounds such as nickel acetylacetonate and nickel diacetone; organic iron compounds such as iron acetylacetonate; metal catalysts such as alkali metal or alkaline earth metal alkoxides and phenoxides such as sodium acetate; tertiary amine catalysts such as triethylamine, triethylenediamine, N-methylmorpholine dimethylaminomethylphenol, and imidazole; organic acid salts and the like. Among these, organotin compounds are particularly preferable. The catalyst may be used in 1 kind, or 2 or more kinds may be used in combination.

The content of the catalyst is preferably 0.03 to 3 parts by mass based on 100 parts by mass of the polyol. Particularly preferably 0.05 to 2.0 parts by mass.

As the foam stabilizer, a silicone foam stabilizer can be used. As the silicone foam stabilizer, a dimethylsiloxane compound, a polyether dimethylsiloxane compound, a phenylmethylsiloxane compound, or the like can be used. The foam stabilizer may be used in 1 kind, or 2 or more kinds may be used in combination.

The content of the foam stabilizer is preferably 1 to 20 parts by mass based on 100 parts by mass of the polyol. Particularly preferably 2 to 10 parts by mass.

Examples of the crosslinking agent include ester oligomers chain-extended with e-caprolactone using ethylene glycol, trimethylolpropane, or the like as an initiator, and trifunctional polyether polyols having a molecular weight of about 300 to 700, and the like; short-chain diol crosslinking agents such as ethylene glycol, diethylene glycol, glycerin, and trimethylolpropane. By using a crosslinking agent having a high molecular weight, a softer foam layer can be obtained. The crosslinking agent may be used in 1 kind, or 2 or more kinds may be used in combination.

The content of the crosslinking agent contained in the raw material of the polyurethane foam layer varies depending on the kind thereof, and is preferably 1 to 10 parts by mass, and particularly preferably 2 to 5 parts by mass, based on 100 parts by mass of the polyol.

The foam material may contain additives such as an ultraviolet absorber, an antioxidant, an organic filler, an inorganic filler, and a colorant, if necessary.

(method for producing polyurethane foam layer)

The raw materials for producing the polyurethane foam layer are a gas-liquid mixture containing the foam raw material having the above-described configuration and a gas, and a resin film layer (C). The gas to be mixed with the foam raw material is not particularly limited, and nitrogen gas, inert gas, dry air, or the like can be used. Among these, nitrogen gas is preferable. The method for producing the polyurethane foam laminate will be specifically described below with reference to fig. 6.

The foam raw material is stirred with a gas by using a mixer 11 to prepare a gas-liquid mixture 21 a. Thereafter, the gas-liquid mixture 21a is supplied so as to be applied to the resin film layer (C)20, and then, a release paper (or a release-treated resin film) 7 is supplied from the upper side of the surface of the cast gas-liquid mixture 21 a. Then, the uncured layer 21b formed of the gas-liquid mixture 21a is passed through a roll coater 12 or the like in this laminated state, whereby the thickness thereof is adjusted. It should be noted that the use of the release paper 7 may be acceptable, and when the release paper 7 is used, the thickness of the uncured layer 21b can be easily adjusted, and a skin layer can be formed on the surface (release paper 7 side) of the foam layer obtained after the heat treatment. Through these steps, a 3-layer laminate having the resin film (C) on one surface side (lower surface) of the uncured layer 21b and the release paper 7 laminated on the other surface side (upper surface) is obtained.

Thereafter, the laminate is heated by a heat treatment apparatus. In this way, the foam raw materials are reacted to cure the uncured layer 21b, thereby obtaining the polyurethane foam laminate 30 having the foam body layer (a) formed thereon. By this production method, the polyurethane foam layer (a) and the resin film layer (C) are firmly joined. The obtained laminate 30 may be wound directly around a paper tube or the like in a 3-layer structure to form a roll, or may be wound as a 2-layer laminate after peeling off the release paper 7 as shown in fig. 6 to form a roll. Further, the sheet may be cut into a predetermined size on a production line and made into a sheet. The sheets can then also be stacked and baled. In this case, the layers may be stacked directly in a 3-layer state, or may be stacked in a 2-layer type stack.

As described above, the raw materials for producing the polyurethane foam laminate include the gas-liquid mixture 21a obtained by using the foam raw material and the gas, and the resin film (C).

The method for producing the above-mentioned foam raw material is not particularly limited, and a method of mixing a polyisocyanate with a mixture (hereinafter referred to as "first mixture") containing no polyisocyanate but containing a polyol, a flame retardant, a catalyst and the like is preferred. In general, additives to be compounded as necessary are contained in the first mixture.

The method for producing the gas-liquid mixture 21a is not particularly limited, and the foam raw material and the gas are mixed so that the foam raw material and the gas are mixed in a volume ratio of preferably 5 to 30 vol% and 70 to 95 vol%, more preferably 8 to 25 vol% and 75 to 92 vol%, respectively, when the total volume of the foam raw material and the gas is 100 vol%. By this mixing ratio, the gas-liquid mixture 21a suitable for forming the foam layer having the above-described specific density can be prepared. The mixer 11 for mixing the foam raw material and the gas is not particularly limited, and an Oaks mixer, a hobart mixer, or the like is preferably used. These mixers 11 can uniformly mix the foam raw material and the gas, and can easily control the foaming, and can produce a foamed gas-liquid mixture 21a in a more homogeneous form.

The method of mixing the foam raw material with the gas is preferably a method of blowing the gas into the foam raw material previously contained in a mixing chamber or the like, or a method of simultaneously supplying the foam raw material and the gas into the chamber. In these cases, the polyisocyanate and the first mixture may be supplied separately to the chamber as the foam raw material.

The foam layer using the gas-liquid mixture is preferably formed by a mechanical foaming method. According to this method, the volume of the gas-liquid mixture used and the volume of the polyurethane foam obtained 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 with respect to the foam raw material.

The gas-liquid mixture 21a is supplied to the surface of the resin film layer (C)20, and then the release paper 7 is supplied to the surface of the cast gas-liquid mixture 21a from the upper side thereof, thereby forming a laminate. Next, the 3-layer laminate is heated by the heat treatment device 13 set to a predetermined temperature, and the foam raw material contained in the uncured layer 21b is reacted to form the foamed layer (a).

The heating method of the 3-layer 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 kind of the polyol and the polyisocyanate and the like in order to cure the foam raw material contained in the uncured layer 21 b. The heating temperature is preferably 120 to 200 ℃, preferably 140 to 180 ℃, and particularly preferably 150 to 170 ℃.

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

Examples of the heat treatment device 13 include a heating furnace and a far infrared ray irradiation device. When a heating furnace is used, the heat treatment can be performed while the 3-layer laminate is stationary or moving by a heat source fixed in the apparatus. At this time, hot air may be supplied. When a polyurethane foam laminate is continuously produced, the 3-layer laminate is preferably heated while being moved in a heating furnace.

The heating of the above-mentioned 3-layer laminate may be performed from either one or both of the resin film side and the release paper side. In the present invention, in order to heat the entire foam layer uniformly and efficiently form a more homogeneous foam layer, it is preferable to heat the foam layer from both sides of the 3-layer laminate.

When the method for producing a polyurethane foam laminate is the production system shown in fig. 6, the preparation of the gas-liquid mixture 21a, the supply of the gas-liquid mixture 21a onto the resin film (C)20, the supply of release paper or the like onto the upper surface of the uncured layer 21b, the thickness adjustment by the roll coater 12 or the like, and the heating of the 3-layer laminate can be continuously performed, thereby continuously producing a polyurethane foam laminate. That is, the gas-liquid mixture 21a prepared by the mixer 11 is continuously fed out, continuously supplied onto the moving resin film (C)20 at a predetermined supply speed, and the release paper 7 is supplied onto the surface of the gas-liquid mixture 21a cast at the same speed as the resin film (C)20, and the thickness thereof is adjusted by the roll coater 12. Thereafter, the 3-layer layered product is introduced into a heat treatment apparatus 13, for example, a heating furnace, which is disposed near the roll coater 12. When a heating furnace is used, the 3-layer laminate is usually introduced from one opening, moved in the heating furnace at a moving speed equal to or close to that of the resin film (C)20, and then taken out from the other opening. Thereby, the polyurethane foam laminate 30 having the release paper 7 was produced. Thereafter, the release paper 7 is removed as necessary, and a polyurethane foam laminate including the foam layer (a) and the resin film layer (C) can be produced.

As described above, the polyurethane foam laminate can be produced by a mechanical foaming method in which water and a foaming agent are not added to the foam raw material. The foam may be produced by a so-called chemical foaming method in which water and/or a foaming agent are mixed into a foam raw material. In this case, ion-exchanged water, tap water, distilled water, or the like can be used as the water. The amount of water used is not particularly limited, but is usually 0.1 to 0.5 parts by mass, and particularly preferably 0.2 to 0.4 parts by mass, based on 100 parts by mass of the polyol. Further, the blowing agent is not particularly limited, and a hydrocarbon, a freon substitute, or the like can be used. The amount of the blowing agent is also not particularly limited. As described above, even in the case of the chemical foaming method using a foam raw material containing water and/or a foaming agent in place of the mechanical foaming method, the foamed state of the gas-liquid mixture is stably maintained without causing cell coarsening or the like, and a foam body layer having a desired density and thickness can be easily formed. As a result, a polyurethane foam laminate having a foam layer having excellent physical properties can be produced.

(method for producing adhesive tape)

The adhesive tape of the present invention may be produced by the following method: for example, (I) a method of producing the foamed sheet by applying the adhesive intermittently to the surface side of the resin film (C) of an article obtained by integrating the foamed body layer (a) and the resin film (C) and drying the adhesive to form the adhesive part (B); (II) a method of intermittently applying the adhesive to a release liner (D), drying the adhesive, etc. to form an adhesive part (B), and bonding the adhesive part (B) to an article obtained by integrating the foam layer (A) and the resin film (C); (III) a method of intermittently applying the adhesive to a release liner (D) and drying the adhesive to form an adhesive part (B), and then bonding the adhesive to a resin film (C) and then forming a foam layer (A) on the resin film (C); (IV) a method of intermittently applying the adhesive to the resin film (C) and drying the adhesive to form the adhesive part (B), then bonding the adhesive part (B) to the release liner (D), and then forming the foam layer (A) on the resin film (C). Among them, the methods (III) and (IV) are preferable because the resin film can be relatively thinned and the productivity is excellent. In particular, the method of (IV) is most preferable.

The adhesive is preferably intermittently applied to at least one surface (a) of the foam base (a) by an application method such as a gravure coating method or a slit die coating method, and is preferably applied by a direct gravure coating method.

The adhesive tape of the present invention has excellent adhesion, cushioning properties, and adhesion workability (bubble removal properties) even when it is extremely thin, and therefore, can be suitably used in the manufacturing field of electronic devices such as portable electronic terminals, for example, which are required to be thin. In particular, by using the rear surface of the display, chipping and waviness of the display device can be prevented, and thinning can be facilitated.

Further, the pressure-sensitive adhesive tape can be suitably used for a display back surface where the performance is likely to be deteriorated due to the remaining of the air bubbles, because the air bubbles are easily removed from the interface between the adherend and the adhesive portion (B) even when a hole or the like is not provided in a part of the pressure-sensitive adhesive tape, and further, the hole forming process for improving the adhesion is not necessary.

Examples

Hereinafter, examples of the present invention will be described, and more specifically, the present invention will be described.

Preparation example 1 adhesive a

An acrylic polymer having a weight average molecular weight of 90 ten thousand was obtained by solution-polymerizing 97.98 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid and 0.02 part by mass of 4-hydroxybutyl acrylate in an ethyl acetate solution at 80 ℃ for 8 hours, using 0.2 part by mass of azobisisobutyronitrile as a polymerization initiator.

A binder solution having a solid content adjusted to 40 mass% was obtained by mixing 5 parts by mass of "D-135" (polymerized rosin ester, available from Mitsuka chemical Co., Ltd.), "20 parts by mass of" KE-100 "(disproportionated rosin ester, available from Mitsuka chemical Co., Ltd.)" and 25 parts by mass of "FTR 6100" (petroleum resin, available from Mitsui chemical Co., Ltd.) "with 100 parts by mass of the acrylic polymer and adding ethyl acetate.

The above adhesive solution was mixed with 2.0 parts by mass of "NC 40" (isocyanate crosslinking agent available from DIC corporation) and stirred, thereby obtaining an adhesive a.

The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive a had a tan δ peak temperature of 0 ℃ and a gel fraction of 40 mass%.

(preparation example 2) adhesive b

An acrylic polymer having a weight average molecular weight of 50 ten thousand was obtained by solution-polymerizing 97.98 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid and 0.02 part by mass of 4-hydroxybutyl acrylate in an ethyl acetate solution at 90 ℃ for 6 hours, using 0.3 part by mass of azobisisobutyronitrile as a polymerization initiator.

A binder solution having a solid content adjusted to 40 mass% was obtained by mixing 5 parts by mass of "D-135" (polymerized rosin ester, available from Mitsuka chemical Co., Ltd.), "20 parts by mass of" KE-100 "(disproportionated rosin ester, available from Mitsuka chemical Co., Ltd.)" and 25 parts by mass of "FTR 6100" (petroleum resin, available from Mitsui chemical Co., Ltd.) "with 100 parts by mass of the acrylic polymer, and adding ethyl acetate.

The above adhesive solution was mixed with 0.6 part by mass of "NC 40" (isocyanate crosslinking agent available from DIC corporation) and stirred, thereby obtaining adhesive b.

The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive b had a tan δ peak temperature of 0 ℃ and a gel fraction of 10 mass%.

(preparation example 3) adhesive c

The above adhesive solution was mixed with 3.3 parts by mass of "NC 40" (isocyanate crosslinking agent available from DIC corporation) and stirred, thereby obtaining an adhesive c.

The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive c had a tan δ peak temperature of 0 ℃ and a gel fraction of 46 mass%.

Preparation example 4 adhesive d

The above adhesive solution was mixed with 1.2 parts by mass of "NC 40" (isocyanate-based crosslinking agent, available from DIC corporation) and stirred, thereby obtaining an adhesive d.

The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive d had a tan δ peak temperature of 0 ℃ and a gel fraction of 20 mass%.

Preparation example 5 adhesive e

An acrylic polymer having a weight average molecular weight of 80 ten thousand was obtained by solution-polymerizing 96.4 parts by mass of n-butyl acrylate, 3.5 parts by mass of acrylic acid, and 0.1 part by mass of 4-hydroxyethyl acrylate in an ethyl acetate solution at 80 ℃ for 8 hours, using 0.2 part by mass of azobisisobutyronitrile as a polymerization initiator.

A binder solution having a solid content of 40 mass% was obtained by mixing 10 parts by mass of "D-135" (polymerized rosin ester, available from Mitsuka chemical Co., Ltd.) and 10 parts by mass of "A100" (disproportionated rosin ester, available from Mitsuwa chemical Co., Ltd.) with 100 parts by mass of the acrylic polymer and adding ethyl acetate.

The above adhesive solution was mixed with 1.3 parts by mass of "NC 40" (isocyanate crosslinking agent available from DIC corporation) and stirred, thereby obtaining an adhesive e.

The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive e had a tan δ peak temperature of-15 ℃ and a gel fraction of 40 mass%.

(preparation example 6) adhesive f

An acrylic polymer having a weight average molecular weight of 80 ten thousand was obtained by solution-polymerizing 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 in an ethyl acetate solution at 70 ℃ for 10 hours, using 0.1 part by mass of azobisisobutyronitrile as a polymerization initiator.

A binder solution having a solid content adjusted to 40 mass% was obtained by mixing 10 parts by mass of "D-135" (polymerized rosin ester, available from Mitsukawa chemical Co., Ltd.) with 100 parts by mass of the acrylic polymer and adding ethyl acetate.

The above adhesive solution was mixed with 1.3 parts by mass of "NC 40" (isocyanate crosslinking agent available from DIC corporation) and stirred, thereby obtaining an adhesive f.

The pressure-sensitive adhesive layer obtained using the pressure-sensitive adhesive f had a tan δ peak temperature of-25 ℃ and a gel fraction of 40 mass%.

(example 1)

The adhesive a was dot-printed on "PET 50 × 1J 0" (release liner having a silicone-based release-treated surface on the surface of a 50 μm polyester film, manufactured by NIPPA corporation) using a gravure coater, and dried at 100 ℃ for 1 minute, thereby obtaining an island-like adhesive portion having a substantially diamond shape and a thickness of 2 μm as shown in fig. 1. In the above-described bonded portions, the distance between any bonded portion and a bonded portion close thereto was 0.1 mm. Next, a 2 μm polyester film (K100-2.0W manufactured by Mitsubishi resin Co., Ltd.) was laminated and attached at a line pressure of 3N/mm using a laminator. This was cured at 40 ℃ for two days to obtain a dot adhesive film. Next, a foam layer was formed on the 2 μm polyester film of the spot adhesive film by the following method.

90 parts by mass of a polyether polyol "GP-3000" manufactured by Sanyo chemical Co., Ltd, 10 parts by mass of a polyether polyol "GP-600" manufactured by Sanyo chemical Co., Ltd, 0.1 part by mass of a catalyst "tin octylate" manufactured by North City chemical Co., Ltd, and 5 parts by mass of a foam inhibitor were mixed and stirred to prepare a mixture. Thereafter, the above mixture and MDI "CORONATE 1130" manufactured by japan polyurethane corporation, which had an isocyanate index of 1, were charged into a chamber equipped with an Oaks mixer. And, at the same time, the density of the foam layer reaches 300kg/m³Nitrogen gas was injected.

Next, in the chamber, the above components were stirred to prepare a foamed gas-liquid mixture. Then, the gas-liquid mixture was fed onto a 2 μm polyester film of a dot adhesive film fed out at a speed of 5 m/min, and a release paper was fed onto the surface of the cast gas-liquid mixture from the upper side thereof at the same speed as that of the dot adhesive film, and the thickness was adjusted to 100 μm by a roll coater, thereby forming an uncured layer made of the gas-liquid mixture.

Thereafter, the laminate composed of the spot adhesive film, the uncured layer and the release paper was put into a 160 ℃ overheating furnace by a far infrared heater and overheated for 1 minute. Next, the release paper was peeled off from the laminate to obtain an adhesive tape in which the dot adhesive film and the foam layer were joined.

(examples 2 to 13)

Adhesive tapes were produced in the same manner as in example 1, except that the shape and area of the adhesive part (B) and the thickness of the adhesive part (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)

An adhesive tape was obtained in the same manner as in example 1, except that the adhesive d was used instead of the 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)

A pressure-sensitive adhesive tape was produced in the same manner as in example 1, except that the shape and area of the pressure-sensitive adhesive portion (B) and the thickness of the pressure-sensitive 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)

Except that the density of the foam layer was changed from 300kg/m³Changed to 200kg/m³Except for this, an adhesive tape was obtained in the same manner as in example 1.

(example 28)

An adhesive tape was obtained in the same manner as in example 1, except that the polyester film of 2 μm was changed to a polyester film of 25 μm.

(example 29)

An adhesive tape was obtained in the same manner as in example 1, except that "PET 25 × 1J 0" (release liner made by NIPPA having a silicone-based release-treated surface on the surface of a 25 μm polyester film) was used in place of "PET 50 × 1J 0" (release liner made by NIPPA having a silicone-based release-treated surface on the surface of a 50 μm polyester film).

(example 30)

90 parts by mass of a polyether polyol "GP-3000" manufactured by Sanyo chemical Co., Ltd, 10 parts by mass of a polyether polyol "GP-600" manufactured by Sanyo chemical Co., Ltd, 0.1 part by mass of a catalyst "tin octylate" manufactured by North City chemical Co., Ltd, and 5 parts by mass of a foam-producing agent were mixed and stirred to prepare a mixture. Thereafter, the above mixture and MDI "CORONATE 1130" manufactured by japan polyurethane corporation, which had an isocyanate index of 1, were charged into a chamber equipped with an Oaks mixer. And, at the same time, the density of the foam layer reaches 300kg/m³Nitrogen gas was injected.

Next, in the chamber, the above components were stirred to prepare a foamed gas-liquid mixture. Then, the gas-liquid mixture was fed onto a 25 μm polyester film "S10-25" manufactured by toyo corporation which was fed at a speed of 5 m/min, and a release paper was fed from the upper side of the cast gas-liquid mixture at the same speed as the 25 μm polyester film, and the thickness was adjusted to 100 μm by a roll coater, thereby forming an uncured layer made of the gas-liquid mixture.

Thereafter, the laminate composed of the polyester film, the uncured layer and the release paper was put into a 160 ℃ overheating furnace by a far infrared heater and overheated for 1 minute. Next, the release paper was peeled off from the laminate to obtain an article in which the polyester film and the foam layer were bonded.

Next, the adhesive a was dot-printed on "PET 50 × 1J 0" (release liner having a silicone-based release-treated surface on the surface of a 50 μm polyester film, manufactured by NIPPA corporation) using a gravure coater, and dried at 100 ℃ for 1 minute, thereby obtaining an island-like adhesive portion having a substantially rhombic shape and a thickness of 2 μm as shown in fig. 1. In the above-described adhesive portions, the distance between any adhesive portion and the adhesive portion adjacent thereto was 0.1 mm. Subsequently, the polyester film layer of the article obtained by joining the polyester film and the foam layer was superimposed and attached at a line pressure of 3N/mm using a laminator. This was cured at 40 ℃ for two days to obtain a dot adhesive film.

Comparative example 1

An adhesive tape was obtained in the same manner as in example 30, except that the adhesive layer was provided on the entire surface of the object by the gravure coater instead of the object having the adhesive layer in an island shape.

(method of measuring gel fraction of adhesive part)

The pressure-sensitive adhesives a to f were each applied to the release-treated surface of a release liner so that the thickness thereof after drying became 50 μm, dried at 100 ℃ for 3 minutes, and then cured at 40 ℃ for 2 days, thereby forming pressure-sensitive adhesive layers. The adhesive layer was cut into a square having a length of 50mm and a width of 50mm, and the square was used as a test piece.

The mass of the test piece (G1) was measured, and then the test piece was immersed in toluene at 23 ℃ for 24 hours. After the immersion, the mixture of the test piece and toluene was filtered using a 300-mesh metal net, and insoluble components in toluene were extracted. The mass of the insoluble matter obtained by drying the insoluble matter at 110 ℃ for 1 hour was measured (G2).

The gel fraction was calculated based on the mass (G1), the mass (G2) and the following formula.

Gel fraction (% by mass) of (G2/G1). times.100

(measurement of dynamic viscoelasticity)

The pressure-sensitive adhesives a to f were applied to the surface of a release liner so that the dry thickness became 50 μm, and dried to form pressure-sensitive adhesive layers, and cured at 40 ℃ for 2 days. The cured adhesive layers were stacked until the total thickness became 2mm, and the resultant was used as a test piece.

Next, the test piece was inserted into a measuring part having a disk shape of a parallel disk with a diameter of 7.9mm by using a viscoelasticity tester (trade name: ARES2KSTD, manufactured by Rheometric Co., Ltd.), and the storage elastic modulus (G') and the loss elastic modulus (G ") at-50 ℃ to 150 ℃ were measured under the conditions of a frequency of 1Hz and a temperature rise time of 1 ℃/1 minute. The loss tangent tan δ was calculated by the following calculation formula.

Loss tangent tan delta ═ G '/G'

(measurement of Total thickness of adhesive tape)

The thickness of the adhesive tape from which the release liner was peeled was measured by using a thickness meter FFG-6 manufactured by kawasaki corporation.

(measurement of adhesion force (1 hour after application))

The adhesive tapes obtained in examples and comparative examples were cut into 20mm wide tapes, and the adhesive layer on one side was backed with a polyethylene terephthalate film having a thickness of 25 μm, and the resulting tapes were used as test pieces. The above-mentioned back-sticking is performed on the surface of the pressure-sensitive adhesive layer having a smooth surface, not on the pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive portion (B) which is a constituent element of the present invention.

The test piece was attached to the surface of a clean and smooth stainless steel plate, and pressed thereon by reciprocating a 2kg roller once, and the thus-obtained object was left to stand at 23 ℃ and 50% RH for 1 hour in accordance with JIS Z-0237, and then the peel adhesion force (peel direction: 90 °, tensile speed: 0.3m/min) was measured at 23 ℃ and 50% RH atmosphere using a TENSILON tensile tester. The measurement results are shown in the column of "adhesion (1 hour after attachment)" in the table.

(measurement of holding force)

The adhesive tapes obtained in examples and comparative examples were cut into 20mm wide tapes, and one side of the adhesive tape was backed with an aluminum foil having a thickness of 50 μm, and the resulting tapes were used as test pieces. The above-mentioned back-sticking is performed on the surface of the pressure-sensitive adhesive layer having a smooth surface, not on the pressure-sensitive adhesive layer corresponding to the pressure-sensitive adhesive portion (B) which is a constituent element of the present invention.

The test piece was attached to the surface of a clean and smooth stainless steel plate so as to have an attachment area of 20mm × 20mm, and the surface was pressed by a 2kg roller while reciprocating the roller once, and the object thus obtained was allowed to stand at 23 ℃ and 50% RH for 1 hour in accordance with JISZ-0237, and then a load of 100g was applied in the shearing direction in an atmosphere of 100 ℃, and the offset distance of the tape after 24 hours was measured. The measurement results are shown in the column "holding power" in the table.

(evaluation of easiness of removal of bubbles)

The adhesive tapes obtained in examples and comparative examples were cut into pieces 50mm in length by 100mm in width, the release liner was peeled off, and aluminum plates 70mm in length by 150mm in width were placed on the surfaces of the adhesive parts in an atmosphere of 23 ℃ and 50% RH for 5 seconds in a state where a load of 5N was applied to the aluminum plates, thereby obtaining temporary stickers.

Next, after inverting the temporary patch, a 2kg roller was reciprocated 1 time from the surface on the adhesive tape side to pressurize them, thereby obtaining a laminate.

10 of the above laminates were produced by the above method. Swelling of the adhesive tape (10 mm) was observed by visual observation²The above bulge) to confirm whether or not air bubbles exist between the adhesive tape and the aluminum plate. The ease of removal of the bubbles was evaluated based on the number of stacked bodies in which the presence of bubbles was not confirmed by the above method.

(evaluation of unevenness of foamed layer)

The foamed layer of the obtained adhesive tape was observed from a position 30cm away from the upper surface of the adhesive tape under a fluorescent lamp, and the presence or absence of unevenness was evaluated.

Very good: without unevenness

O: slight unevenness

X: with obvious unevenness

(evaluation of appearance)

The adhesive tape was attached to an aluminum plate, and evaluation was made based on whether or not the shape of the adhesive part (the above-described substantially rhombic shape, substantially circular shape, and the like) could be visually recognized when observed from a position 30cm away from the upper surface of the adhesive tape under a fluorescent lamp. A person who could not visually recognize the shape of the adhesive portion at all was rated "x", a person who could slightly visually recognize the shape was rated "o", and a person who could clearly visually recognize the shape was rated "x". In the case where the pressure-sensitive adhesive layer was formed by applying the pressure-sensitive adhesive to the entire surface of the foam base as in comparative example 1, the shape of the pressure-sensitive adhesive portion was not visually recognized by the above method because the shape was not formed in a predetermined shape, and thus it was represented by "-" without evaluation.

(number of bonded portions)

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

[ Table 1]

[ Table 2]

[ Table 3]

[ Table 4]

[ Table 5]

[ Table 6]

[ Table 7]

In the table, "substantially rhombic 1" means a rhombic bonded portion having an angle of 60 ° at a corner facing the flow direction of the adhesive tape (an angle of 120 ° at a corner facing the width direction), "substantially rhombic 2" means a rhombic bonded portion having an angle of 30 ° at a corner facing the flow direction of the adhesive tape (an angle of 150 ° at a corner facing the width direction), "substantially square" means a square bonded portion having an angle of 90 ° at a corner facing the flow direction of the adhesive tape (an angle of 90 ° at a corner facing the width direction), "substantially circular" means a bonded portion having a shape shown in fig. 2, "substantially hexagonal (oblique line)" means a bonded portion having a shape shown in fig. 3, and "substantially quadrangular (oblique line)" means a bonded portion having a shape shown in fig. 4.

The adhesive tapes of the examples each had a plurality of independent adhesive layers on one surface, and therefore were excellent in ease of removal of air bubbles. Further, the pressure-sensitive adhesive tape of the examples was thin, but had no unevenness of the foamed layer and also had excellent adhesion and holding power. On the other hand, in the adhesive tape of the comparative example, the adhesive layer was not provided in an island shape but was provided over the entire surface, and therefore, there was no passage for removing bubbles, and the ease of removing bubbles was significantly poor.

Description of the symbols

1 foam layer

2 bonding part

3 adhesive tape

4 graphite flake

5 Single-sided adhesive tape

6 double-sided adhesive tape

7 Release paper

11 mixer for mixing foam material and gas

12 roller coater

13 heat-treated layer

20 resin film (C) or an article obtained by integrating resin film (C), adhesive part (B) and release liner (D)

21a gas-liquid mixture

21b uncured layer

30 laminated body

Claims

1. An adhesive tape comprising a foam layer A, a resin film layer C, and 2 or more adhesive parts B on the resin film C side, wherein a region having no adhesive part B is present between the 2 or more adhesive parts B and the region is open to an end of the adhesive tape,

the size of each 1 arbitrary bonding part B1 selected from the bonding parts B was 0.001mm in area²～100mm²，

The distance between any bonding part B1 selected from the 2 or more bonding parts B and the bonding part B2 close to the bonding part B1 is 0.5mm or less.

2. The adhesive tape according to claim 1,

the size of each 1 arbitrary bonding part B1 selected from the bonding parts B was 0.01mm in area²～25mm²。

3. The adhesive tape according to claim 1 or 2,

the distance between any bonding part B1 selected from the 2 or more bonding parts B and the bonding part B2 close to the bonding part B1 is 0.2mm or less.

4. The adhesive tape according to any one of claims 1 to 3,

the adhesive part B has a gel fraction of 10 to 60 mass%.

5. The adhesive tape according to any one of claims 1 to 4,

the peak temperature of the loss tangent of the adhesive part B is-30 ℃ to 20 ℃.

6. The adhesive tape according to any one of claims 1 to 5,

the thickness of the adhesive part B is 1-10 μm.

7. The adhesive tape according to any one of claims 1 to 6,

the thickness of the resin film layer C is 1-50 μm.

8. The adhesive tape according to any one of claims 1 to 7,

a release liner D is provided on the surface contacting the adhesive part B.

9. The adhesive tape according to any one of claims 1 to 8,

the shape of the adhesive portion B when the adhesive portion B is viewed from the side of the one surface a of the foam layer a is substantially circular, substantially quadrangular, or substantially hexagonal.

10. The adhesive tape according to any one of claims 1 to 9,

the shape of the adhesive portion B when the adhesive portion B is viewed from the side of the one surface a of the foam layer a is substantially circular, substantially square, substantially rhombic, or substantially hexagonal.

11. The adhesive tape according to any one of claims 1 to 10,

the ratio of the area having the adhesive portion B to the area of the one surface a of the foam layer a is 10% to 99%.

12. The adhesive tape according to any one of claims 1 to 11,

10 to 1000000 of the adhesive parts B are present in the range of 5cm in the flow direction and 5cm in the width direction of the adhesive tape.

13. The adhesive tape according to any one of claims 1 to 12,

the adhesive tape has 150 to 50000 adhesive parts B in the range of 5cm in the flow direction and 5cm in the width direction.

14. The adhesive tape according to any one of claims 1 to 13,

the foam layer A is a polyurethane foam layer or an acrylic foam layer.

15. The adhesive tape according to any one of claims 1 to 14, wherein the foam layer A has a load at 50% compression of 0.003 to 1 MPa.

16. The adhesive tape according to any one of claims 1 to 15, which has a 180 ° peel adhesion in the range of 2N/20mm to 12N/20mm as measured using a test piece obtained by,

the test piece is as follows: a smooth stainless steel plate was placed on the surface having the adhesive portion B, pressed against the surface by a 2kg roller while reciprocating once, and left at 23 ℃ and 50% RH for 1 hour to obtain a test piece.

17. The adhesive tape according to any one of claims 1 to 16, which has a holding force of 0.5mm or less.

18. A method for producing an adhesive tape, which is the method for producing an adhesive tape according to any one of claims 1 to 17,

the method is characterized by comprising the following steps:

a step of intermittently applying an adhesive to the release liner D or the resin film C to form an adhesive part B; and

and a step of applying a foam layer A to the resin film layer C of an article obtained by integrating the resin film layer C, the adhesive section B, and the release liner D.

19. The adhesive tape manufacturing method according to claim 18,

the viscosity of the adhesive is in the range of 0.1 mPas-1000 mPas.

20. The adhesive tape manufacturing method according to claim 18 or 19,

the adhesive is intermittently applied so that the shape of the adhesive portion B is formed into a substantially circular shape, a substantially quadrangular shape, or a substantially hexagonal shape.

21. A display device, wherein the adhesive tape according to any one of claims 1 to 17 is provided on a non-display surface side of a display.