KR20100112528A - Double sided pressure sensitive adhesive tape - Google Patents

Abstract

PURPOSE: A double-side adhesive tape is provided to secure the improved rework property, and adhesive property with an object, and to effectively prevent the insertion of water. CONSTITUTION: A double-side adhesive tape(1) includes adhesive layers on both sides of a foam material. The interlayer strength of the foam material is more than 12 N/cm. The 25% compressive strength is 30~170 killo pascals. The adhesive layers are formed with an acrylic adhesive composition. The acrylic adhesive composition includes an acrylic copolymer with a vinyl monomer and (meth)acrylate, and a polymerized rosin ester group tackifying resin.

Description

Double-sided adhesive tape {DOUBLE SIDED PRESSURE SENSITIVE ADHESIVE TAPE}

This invention relates to the double-sided adhesive tape centered on a foam base material.

In portable electronic devices such as an electronic notebook, a mobile phone, a PHS, a camera, a music player, and a television, a double-sided adhesive tape is used for fixing various members and modules, including bonding of the protection panel and the housing of the information display unit. It is used. In order to secure a competitive advantage in the market, various functions are required, and one of them is required to provide a waterproof function.

As an adhesive tape used for fixing parts of an electronic device, it has the maximum value of loss tangent (tan-delta) in the temperature range of -40--15 degreeC, for example, and the surface adhesive strength with respect to a specific to-be-adhered body is 19N / cm <^2>. The double-sided adhesive sheet in which the above adhesive layer was provided on both surfaces of the support body is disclosed (refer patent document 1). By having a specific adhesive layer, the said double-sided adhesive sheet has favorable adhesive force, and has the outstanding impact resistance which is hard to produce the fall of the component by the impact at the time of the fall of an object. However, when bonding rigid bodies together, such as adhesion of a protection panel and a housing, and adhesion of a housing and a housing, since the said double-sided adhesive sheet hardly obtains a perfect close_contact | adherence with the to-be-adhered body, a slight clearance gap In some cases, immersion occurred.

As a double-sided adhesive tape excellent in adhesiveness, the acrylic pressure-sensitive adhesive layer having a foam as a base material and having a maximum temperature of loss tangent (tanδ) at -25 ° C or less and a holding time in a holding test at 0 ° C is 24 hours or longer. The double-sided adhesive tape which has a is disclosed (refer patent document 2). The said double-sided adhesive tape is excellent in adhesiveness to a to-be-adhered body, and can bond together between members suitably at the time of adhesion | attachment of members. However, it is difficult to suppress even a slight gap at the interface between the member and the adhesive layer only by using the foam as a substrate, and if there is a gap or moxibustion where water can invade even a part of the interface, there is a Because of the expansion, it was difficult to realize waterproofness. In particular, in the use of portable electronic devices, in the case where narrow tape width or thin tape thickness is required in accordance with the demand for narrowing softening and thinning in recent years, it is difficult to provide sufficient waterproofness. It was.

In addition, portable electronic devices or the like separate housings or parts in order to improve the yield at the time of manufacture, to peel off (rework) double-sided adhesive tapes or parts that have failed to be joined from the workpiece, or to repair, regenerate, or reuse the finished product. Although it may be disassembled or dismantled, a conventional double-sided adhesive tape of a foam base material can be easily removed and removed on the surface of the part due to interlayer breakage of the foam base. It was to reduce the efficiency of the work of reattaching, the yield of the housing and the parts, the product, and the recycling rate.

However, in the conventional foam base material, flexibility (compressive strength) when compressed in the thickness direction has been obtained, but there is no concept of strength (interlayer strength) in the case of stretching in the thickness direction. Moreover, when the adhesive force of an adhesive was simply made low, since adhesiveness with a to-be-adhered body also falls, provision of sufficient waterproofness was difficult.

Japanese Patent Application Laid-Open No. 2005-187513 Japanese Patent Application Laid-Open No. 2005-281360

The problem to be solved by this invention is providing the double-sided adhesive tape excellent in favorable adhesiveness with a to-be-adhered body, followability, rework aptitude, and re-peelability.

Furthermore, in addition to the said subject, it is providing the waterproof double-sided adhesive tape suitable for electronic device uses which has the outstanding waterproof function.

Furthermore, in addition to the said subject, it is providing the waterproof double-sided adhesive tape which is excellent in impact resistance, and is suitable for a portable electronic device use.

As a result of intensive studies, the present inventors have used a foam substrate having a specific flexibility and interlaminar strength as a substrate, and a pressure-sensitive adhesive composed of a specific composition and formulation, so that excellent adhesion and rework between the double-sided adhesive tape and the adherend even when bonding the rigid bodies together. Aptitude and re-peelability were realized, and it was found out that water immersion can be effectively prevented, and solved the said subject.

That is, this invention is a double-sided adhesive tape which has an adhesive layer on both surfaces of a foam base material, The interlaminar strength of the said foam base material is 12 N / cm or more, 25% compressive strength is 30-170 kPa, The said adhesive layer is C4-C12 An acrylic copolymer having a (meth) acrylate and a vinyl monomer having a carboxy group as a monomer component and an acrylic pressure-sensitive adhesive composition containing a polymerized rosin ester-based tackifying resin are provided.

In the double-sided adhesive tape of the present invention, the interlayer breakage of the foam substrate is less likely to occur, and even when an interlayer crack occurs, the adhesive can be easily peeled off without remaining on the surface of the part. When peeling (reworking) double-sided adhesive tape or parts, or removing, disassembling, or disassembling the housing or parts for repair, regeneration, or reuse of finished products such as portable electronic devices, the double-sided adhesive tape is used for housing or parts. The efficiency of the reattachment of the new double-sided adhesive tape after removal from the membrane, the yield of the housing or component, the product, and the recycling rate can be improved.

Moreover, it shows favorable adhesiveness with a to-be-adhered body, can prevent the penetration of water from an adhesion gap effectively, and has the outstanding waterproof function. For this reason, thinning progresses, the volume limitation in a housing is severe, and even if it is difficult to provide another water-sealing means, it can effectively provide a waterproof function.

BRIEF DESCRIPTION OF THE DRAWINGS The conceptual diagram which shows the acrylic board with a double-sided adhesive tape for followability test.
2 is a conceptual diagram showing a stepped acrylic plate for followability test.
The conceptual diagram which looked at the state which bonded the acryl plate with a double-sided adhesive tape of a follow-up test, and the stepped acryl plate in the cross section direction.
4 is a conceptual diagram showing a test piece for waterproof test 2. FIG.
Fig. 5 shows the test piece for measuring stand waterproof test 2 on the 'co' shaped measuring stand 6 (made of aluminum having a thickness of 5 mm) with the acrylic plate facing downward, and the bottom side of the measuring stand 6; Conceptual view seen from.
6 is a conceptual diagram showing an operation of giving a drop impact;
7 is a conceptual diagram showing a test piece of an airtight test.
8 is a conceptual diagram illustrating an operation of applying pressure to a test piece.

This invention is a double-sided adhesive tape which has an adhesive layer on both surfaces of a foam base material, The interlaminar strength of the said foam base material is 12 N / cm or more, 25% compressive strength is 30-170 kPa, The said adhesive layer is C4-C12 It is a double-sided adhesive tape which consists of an acryl-type copolymer which has the vinyl monomer which has a (meth) acrylate and a carboxy group as a monomer component, and an acrylic adhesive composition containing superposition | polymerization rosin-ester tackifying resin.

[Foam base material]

The foam base material used for this invention is a foam base material of 12 N / cm or more of interlayer strength, Preferably it is 15-40 N / cm, More preferably, 18-35 N / cm. By using a foam having an interlaminar strength in the above range, the peelability of the double-sided adhesive tape can be imparted even when the interlayer cracking of the substrate occurs in the flexible foam substrate.

In addition, the interlayer strength is first bonded to both sides of the foam for evaluating the interlayer strength, one by one, 50 μm thick adhesive layer, then aged at 40 ° C. for 48 hours to prepare a double-sided adhesive tape for interlayer strength measurement. To make.

Next, a double-sided adhesive tape sample having a width of 2 cm and a length of 10 cm (the flow direction of the polyolefin-based foam) obtained by contacting one side of the adhesive surface with a polyester film having a thickness of 25 μm was subjected to a stainless steel plate (the surface was ## at 23 ° C. 50% RH). After hairline treatment with 360 times of domestic abrasive paper), it is press-bonded with 1 kg of 2 kg rollers, and it is left to stand at 40 degreeC for 48 hours. After standing at 23 ° C. for 24 hours, the strength at the time of tearing the foam in the 90 degree direction at a tensile rate of 300 mm / min under 23 ° C. 50% RH is measured.

The foam base material used for this invention is a foam base material with 25% compressive strength of 30-170 kPa, Preferably it is 40-150 kPa. By using the foam base material whose 25% compressive strength is the said range, it has the outstanding adhesiveness with a to-be-adhered body, and especially adheres also to the to-be-adhered body which has an uneven shape and roughness, and has the outstanding adhesiveness. Moreover, since the foam base material of the said compressive strength has moderate cushioning property, since the pressure at the time of affixing it is easy to extrude the air which exists in an adhesive interface by concentrating on a joining part, the gap which a water enters also produces in the joining of rigid bodies. Excellent adhesion can be achieved.

Moreover, 25% compressive strength overlaps the sample cut | disconnected by 50 mm square | tilt until it becomes about 10 mm in thickness. The sample is sandwiched by a plate having a larger area than the sample, and the sample is compressed by about 2.5 mm (25% of the original thickness) at 23 mm and the speed is stopped, and the strength after 20 seconds is measured.

As for the foam base material used for this invention, the tensile elasticity modulus of a foam base material is 200 N / cm <^2> or more. Tensile strength per unit width is 10 N / cm or more, Preferably it is 12.5 N / cm or more, More preferably, it is 14 N / cm or more. The elongation at break is not particularly limited, but is 100 to 1000%, preferably 300 to 700%. Even if it is a flexible base material foamed with the foam base material whose tensile elasticity modulus, tensile strength, and cut elongation are the said ranges, the deterioration of workability, tearing of a double-sided adhesive tape, and the fall of sticking workability can be suppressed. In addition, when the double-sided adhesive tape is peeled off, interlayer breakage of the foam hardly occurs, and even when interlayer cracking occurs, the peelability of the double-sided adhesive tape can be imparted.

In addition, the above-mentioned tensile elasticity modulus and the tensile strength per width are the tensile velocity in the environment of 23 degreeC * 50% RH using the Denshiron tensile tester for the sample of 2 cm in length (flow direction of a foam base material), and the width of 1 cm. Maximum strength measured under 300 mm / min measurement conditions.

The foam structure of the foam base material used in the present invention is preferable because the foam structure of the foam base material can be effectively prevented from immersion from the cut surface of the foam base material. Although the bubble shape which forms an independent bubble structure is not specifically limited, Since the independent bubble of the shape where the average bubble diameter of a flow direction, the width direction, or both is longer than the average bubble diameter of the thickness direction of a foam has moderate cushioning property, it is preferable. Do.

Although the foaming ratio of a foam base material is not specifically limited, Since it is easy to realize the outstanding adhesiveness and easy peelability with an to-be-adhered body by adjusting interlayer strength, compressive strength, etc. to the said range, 2 to 12 times, Preferably it is 2 It is-8 times, More preferably, it is 2.4 to 5 times.

The average bubble diameter in the thickness direction of the foam base material is 1 to 200 µm, preferably 5 to 150 µm, more preferably 10 to 100 µm, depending on the thickness of the foam. The average bubble diameter of the flow direction and the width direction of a foam base material becomes like this. Preferably it is 1.2-700 micrometers, More preferably, it is 10-500 micrometers, More preferably, it is 100-400 micrometers. By making the average bubble diameter into the said range, even if the width | variety of a double-sided adhesive tape is narrowed, it is easy to hold an independent bubble, and the submerged path | route from the cross section of a foam base material can be interrupted suitably.

Although the ratio of an average bubble diameter is not specifically limited, The ratio (average bubble diameter / thickness direction in a flow direction) of the average bubble diameter in the flow direction of a foam base material with respect to the average bubble diameter in the thickness direction of a foam base material The average bubble diameter in () is preferably from 1.2 to 15, more preferably from 2 to 9. Moreover, the ratio (average bubble diameter in the width direction / average bubble diameter in the width direction) of the average bubble diameter in the width direction of a foam base material with respect to the average bubble diameter in the thickness direction of a foam base material is 1.2. -15 is preferable, More preferably, it is 2-11. Moreover, it is further more preferable that it is the said ratio range in both a flow direction and a width direction. When the said ratio is 1.2 or more, it is easy to ensure the flexibility of the thickness direction, and followability improves. Moreover, if it is 15 times or less, the nonuniformity of the flexibility and tensile strength of the flow direction and width direction of a foam base material hardly arise.

Moreover, as for the ratio of the average bubble diameter of a flow direction and a width direction, 0.25-4 times are preferable when the flow direction is set to 1, More preferably, it is 0.33-3 times. If it is the said ratio range, the nonuniformity of the flexibility and tensile strength of the flow direction and width direction of a foam base material hardly arise.

The average bubble diameter of the width direction of a foam base material and a flow direction is measured with the following method. First, the foam base material is cut | disconnected in the width direction and the flow direction by 1 cm. Next, after expanding the cut surface center part of the cut | disconnected foam base material 50 times with a scanning electron microscope (SEM), the width direction of a foam base material or the width direction of a foam base material so that the cut surface of a foam base material may enter into a photograph over the full length of the base material thickness direction. Photograph the cross section in the flow direction. In the obtained photograph, all the bubble diameters which exist in the cutting surface for 2 mm for the actual length before expansion of a flow direction or the width direction are measured, and an average bubble diameter is computed from the average value.

The average bubble diameter of the thickness direction of a foam base material is measured with the following method. First, the thickness of the foam base material photographed by SEM is measured. Next, SEM photographing is performed on the conditions similar to the average bubble diameter measurement of the flow direction of a foam base material. Next, in the obtained photograph, the number of bubbles of the thickness direction which exists in arbitrary places of a foam base material is visually counted, and the average bubble diameter of the thickness direction is computed from the following formula | equation.

Average bubble diameter (micrometer) in thickness direction = thickness (micrometer) of foam base material / number of bubbles

This is measured at three arbitrary places, and makes the average value into the average bubble diameter in a thickness direction.

The interlaminar strength, compressive strength, tensile modulus, and the like of the foam base material can be appropriately adjusted by the raw material and the foam structure of the base material to be used. Although the kind of foam base material used for this invention will not be restrict | limited especially if it has the said interlayer strength, compressive strength, tensile elasticity modulus, etc., The polyolefin which consists of polyethylene, a polypropylene, ethylene propylene copolymer polymer, ethylene-vinyl acetate copolymer polymer, etc. Rubber foams composed of foams, polyurethane foams, acrylic rubbers, and other elastomers can be used, and among them, to produce a foam base material having a thin independent bubble structure excellent in followingability to irregularities on the surface of the adherend, buffer absorption, and the like. Since it is easy, a polyolefin foam can be used preferably.

Although the thickness of a foam base material may adjust suitably according to the aspect to be used, it is 50-1200 micrometers. In the case of fixing a part of an electronic device, especially a small and thin portable electronic device, since a thin tape thickness is required, it is preferable that the base material thickness is 50-500 micrometers, and it is preferable that it is 70-400 micrometers.

Such foam base material is foamed, stretched, thinned after crosslinking an expandable polyolefin resin sheet formed by supplying a polyolefin resin, a thermal decomposition foaming agent, etc. to an extruder, melt kneading, and extruding it into a sheet form from an extruder with an electron beam. The crosslinked polyolefin resin foam obtained by making it come is mentioned. Although a conventionally well-known thing can be used for polyolefin resin, It is preferable to contain 40 mass% or more of polyethylene-type resin obtained using the metallocene compound containing a tetravalent transition metal. In addition, after foaming the foam, the foam sheet may be sliced in the thickness direction, and then stretched with a hot roll to be skinned.

In the foam base, as an additive, a plasticizer, a softener, an antioxidant, a flame retardant, a filler such as fiber, balloon, bead, metal powder made of glass or plastic, a colorant such as a pigment, a dye, a leveling agent, a thickener, a water repellent, an antifoaming agent, and the like. Known things, such as these, can be added arbitrarily to resin.

The foam base material may be subjected to surface treatment such as corona treatment, flame treatment, plasma treatment, hot air treatment, ozone / ultraviolet treatment, application of an easy adhesion treatment agent, and the like in order to improve adhesion to the pressure-sensitive adhesive layer and other layers. In the surface treatment, the wettability index of the wetting reagent is 36 mN / m or more, preferably 40 mN / m, more preferably 48 mN / m, whereby good adhesiveness with the pressure-sensitive adhesive is obtained.

[Adhesive Layer]

The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive tape of the present invention comprises an acrylic copolymer having a vinyl monomer having 4 to 12 carbon atoms and a carboxyl group as the monomer component, and a polymerized rosin ester tackifying resin. It consists of the acrylic adhesive composition containing, It is characterized by the above-mentioned.

As a C4-C12 (meth) acrylate, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (Meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. A monomer is mentioned, These 1 type, or 2 or more types are used. Especially, the (meth) acrylate of 4-8 carbon atoms of an alkyl group, especially n-butylacrylate is preferable because it is easy to ensure adhesiveness with a to-be-adhered body, and is excellent in cohesion force and resistance to sebum. . As for content of n-butylacrylate, 60 mass% or more of all the C4-C12 (meth) acrylates is preferable, and it is more preferable that it is 90 mass% or more.

It is preferable that it is 80-98.5 mass% in the monomer component which comprises an acrylic copolymer, and, as for content of the (meth) acrylate in an acryl-type copolymer, it is more preferable that it is 90-98.5 mass%.

As a vinyl monomer which has a carboxyl group, acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth) acrylic acid dimer, crotonic acid, ethylene oxide modified succinic acid acrylate, etc. can be used, and especially acrylic acid is used as a copolymerization component. It is preferable.

As for content of the vinyl monomer which has a carboxyl group in an acryl-type copolymer, 0.5-10.0 mass% in the monomer component which comprises an acryl-type copolymer is preferable, and 1.5-5.0 mass% is more preferable.

Moreover, the acrylic copolymer used for the adhesive composition which comprises the adhesive layer of the double-sided adhesive tape of this invention contains the vinyl monomer which has a tertiary amide skeleton in a molecule | numerator as a monomer component, and is excellent in cohesion force and suppressing excessive adhesive force improvement. Therefore, polystyrene, ABS, acrylic, polycarbonate, polyamide polyester, polypropylene, polyurethane, resins such as phenol resin, stainless steel, aluminum, galvanized steel sheet, etc. It is preferable for both good adhesion, rework aptitude, and re-peelability with respect to metal, glass, etc.

As the vinyl monomer having a tertiary amide skeleton in the molecule, N-vinylpyrrolidone, N-vinyl caprolactam, acryloyl morpholine, N, N-dimethylacrylamide, and the like can be used. Preference is given to using ralidone as a copolymerization component.

0.5-5.0 mass% is preferable, and, as for content of the vinyl monomer which has a tertiary amide frame | skeleton in a molecule | numerator in an acryl-type copolymer, 1.5-3.0 mass% is more preferable.

Moreover, when using an isocyanate type crosslinking agent as a crosslinking agent of the acryl-type copolymer used for this invention, use of a hydroxyl group containing vinyl monomer is preferable as a vinyl monomer which has a functional group reacting with this.

As a vinyl monomer which has a hydroxyl group, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl ( Hydroxyl group-containing (meth) acrylates, such as a meth) acrylate, can be used, Especially, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are especially preferable. It is preferable that it is 0.01-1.0 mass% of the monomer component which comprises an acryl-type copolymer, and, as for content of the hydroxyl group containing vinyl monomer reacting with an isocyanate type crosslinking agent, 0.03-0.3 mass% is especially preferable.

As other vinyl monomers, sulfonic acid group-containing monomers such as vinyl acetate and 2-acrylamide-2-methylpropanesulfonic acid, (meth) acrylates having 1 to 3 carbon atoms, (meth) acrylates having 13 or more carbon atoms, and isobornyl Known vinyl monomers, such as (meth) acrylate and styrene, are mentioned.

It is preferable that content of another vinyl monomer is 1.5-20 mass% in the monomer component which comprises an acryl-type copolymer, It is more preferable that it is 1.5-10 mass%, It is further more preferable that it is 2-8 mass%. By containing in the said range, it is easy to adjust the cohesion force, holding force, and adhesiveness of an adhesive to the suitable range.

Although an acryl-type copolymer can be obtained by copolymerizing by well-known polymerization methods, such as solution polymerization method, block polymerization method, suspension polymerization method, and emulsion polymerization method, solution polymerization method and block polymerization method are preferable at the water resistance of an adhesive. The method of initiation of polymerization is also a method of initiation by heat using a peroxide-based, such as benzoyl peroxide or lauroyl peroxide, or an azo-based thermal polymerization initiator such as azobisisobutylnitrile, acetophenone, benzoin ether, or benzylke. The method of starting by ultraviolet irradiation or the method by electron beam irradiation can be arbitrarily selected using a photopolymerization initiator of a de-systemic, acylphosphine oxide-based, benzoin-based or benzophenone-based.

As for the molecular weight of the said acryl-type copolymer, the weight average molecular weight in standard polystyrene conversion measured by a gel permeation chromatograph (GPC) is 40-1,600,000, Preferably it is 60-1,200,000.

In the acrylic adhesive composition used for this invention, in order to make adhesiveness with a to-be-adhered body compatible, rework suitability, and re-peelability, it is preferable to use superposition | polymerization rosin-ester tackifying resin. The softening point of polymerization rosin ester tackifying resin is 100-180 degreeC, Preferably it is 120 degreeC-160 degreeC.

The compounding quantity of polymerization rosin ester tackifying resin is 10-40 mass parts with respect to 100 mass parts of acrylic copolymers, Preferably it is 13-30 mass parts. Moreover, 1 type (s) or 2 or more types may be used for polymerization rosin ester tackifying resin.

In addition, in the acrylic adhesive composition used for this invention, one or more types of tackifying resins other than superposition | polymerization rosin-ester tackifying resin can be used for the purpose of adjusting adhesiveness with a to-be-adhered body, rework aptitude, and re-peelability. . As other tackifying resin, rosin type, polymeric rosin type, rosin phenol type, stabilized rosin ester type, disproportionated rosin ester type, hydrogenated rosin ester type, terpene type, terpene phenol type, petroleum resin type, (meth) An acrylate resin etc. can be illustrated. When using for the adhesive type adhesive composition, it is preferable to use emulsion type tackifying resin.

Especially, disproportionated rosin ester tackifying resin, rosin phenol type tackifying resin, hydrogenated rosin ester tackifying resin, and (meth) acrylate type resin are preferable, and the disproportionated rosin ester system of softening point of 60-130 degreeC is preferable. Tackifying resins are particularly preferred.

It is preferable that the compounding quantity at the time of using other tackifying resin is the compounding quantity or less of the polymerization rosin-ester tackifying resin with respect to 100 mass parts of acrylic copolymers, More preferably, the tackifying resin with respect to 100 mass parts of acrylic copolymers is carried out. The total is 10-30 mass parts. By making ratio of both into the said range, adhesiveness with a to-be-adhered body becomes easy to be ensured.

In an acrylic adhesive composition, in order to raise the cohesion force of an adhesive layer, it is preferable to crosslink an adhesive. As such a crosslinking agent, an isocyanate crosslinking agent, an epoxy crosslinking agent, a metal chelate crosslinking agent, an aziridine crosslinking agent, etc. are mentioned. Especially, the crosslinking agent of the type which adds after completion | finish of superposition | polymerization and advances a crosslinking reaction is preferable, The isocyanate type crosslinking agent and epoxy type crosslinking agent which are rich in reactivity with a (meth) acrylic copolymer are preferable, and adhesiveness with a foam base material improves Therefore, an isocyanate crosslinking agent is more preferable.

Examples of the isocyanate-based crosslinking agent include tolylene diisocyanate, naphthylene-1,5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, trimethylolpropane modified tolylene diisocyanate and the like. Particularly preferred are trifunctional polyisocyanate compounds. As a trifunctional isocyanate type compound, tolylene diisocyanate, these trimethylol propane adducts, triphenylmethane isocyanate, etc. are mentioned.

As an index of the degree of crosslinking, the value of the gel fraction for measuring the insoluble content after immersing the pressure-sensitive adhesive layer in toluene for 24 hours is used. The gel fraction is preferably 25 to 70 mass%. More preferably, both cohesion and adhesiveness are good in it being the range of 30-60 mass%, More preferably, it is 33-55 mass%.

In addition, the measurement of a gel fraction is based on the following. The adhesive composition is coated on the release sheet so that the thickness after drying is 65 μm, dried at 100 ° C. for 5 minutes, and cut at 40 ° C. for 2 days at 50 mm angle to obtain a sample. Next, the weight (G1) before the toluene immersion of the sample was measured in advance, and the toluene insoluble fraction of the sample after immersion in the toluene solution at 23 ° C. for 24 hours was separated by filtration with 300 mesh iron, and then separated at 110 ° C. The weight (G2) of the residue after drying for 1 hour is measured, and a gel fraction is obtained according to the following formula.

Gel fraction (mass%) = (G2 / G1) * 100

As an additive, if necessary, plasticizers, softeners, antioxidants, fillers such as glass, plastic, balloon, bead, metal powder made of glass and plastics, colorants such as pigments and dyes, leveling agents, thickeners, water repellents, antifoaming agents and the like It can be added arbitrarily to an adhesive composition.

As for the adhesive layer used for the double-sided adhesive tape of this invention, it is preferable that the temperature which shows the maximum value of loss tangent (tan-delta) in frequency 1Hz is -30 degreeC-10 degreeC. It is more preferable that it is -30 degreeC-0 degreeC, and it is more preferable that it is -25 degreeC --5 degreeC especially at the time of the improvement of fall impact resistance under low temperature environment.

Moreover, the temperature which shows the maximum value of loss tangent (tan-delta) in frequency 1 Hz of the double-sided adhesive tape of this invention becomes like this. Preferably it is -30 degreeC-20 degreeC, More preferably, it is -30 degreeC-10 degreeC, Preferably they are -25 degreeC-5 degreeC. The maximum value of the loss tangent tan δ at the frequency of 1 Hz is 1.0 or less, preferably 0.8 or less. By setting the temperature which shows the maximum value of the loss tangent of an adhesive layer, or the temperature which shows the maximum value and the maximum value of the loss tangent of a double-sided adhesive tape to the said range, favorable adhesiveness with a to-be-adhered body at normal temperature and fall impact resistance in a low temperature environment of 0 degrees C or less It becomes easy to give it.

Moreover, although the storage elastic modulus (G ') in frequency 1Hz of the adhesive layer used for the double-sided adhesive tape of this invention is a range which satisfy | fills the said loss tangent (tan-delta), it will not specifically define but the storage elastic modulus in 20 degreeC When (G ') is 2.6 * 10 <^5> Pa or more, Preferably it is 3.0 * 10 <^5> Pa or more, the internal pressure raises with the increase of the apparatus temperature in electronic equipment with high airtightness, or the water pressure (0.11 MPa) of 1 m depth or more When a force is applied from the direction in which the component fixed with the double-sided adhesive tape is pushed and peeled off, it becomes easy to give resistance (airtightness).

The loss tangent tan δ is determined from the equation of tan δ = G ″ / G ′ from the storage modulus G 'and the loss modulus G ″ obtained by the dynamic viscoelasticity measurement by temperature dispersion. In the measurement of dynamic viscoelasticity by temperature dispersion, a temperature representing the maximum and maximum values of loss tangent (tanδ) at a certain frequency is obtained.

The dynamic viscoelastic properties include the kind and proportion of monomers used in the acrylic copolymer constituting the pressure sensitive adhesive, the kind and amount of the polymerization initiator, the amount and the amount thereof used, the crosslinking agent, and the type and amount of the tackifying resin such as the polymerized rosin ester-based tackifying resin and the polymerization method. It can adjust by selecting suitably.

In addition, the dynamic viscoelasticity characteristic of the above-mentioned adhesive layer is prescribed | regulated by the loss tangent of a dynamic viscoelastic spectrum, or loss tangent, and storage elastic modulus at a specific frequency and specific temperature, and also the dynamic viscoelastic spectrum at a specific frequency. It is specified by the temperature representing the maximum value of the loss tangent or the maximum value of the loss tangent. In the measurement of the dynamic viscoelasticity, a test piece was sandwiched between parallel disks, which are measuring sections of the tester, using a viscoelastic tester (trade name: Ares 2KSTD), and the storage modulus from -50 ° C to 150 ° C at a frequency of 1 Hz. (G ') and loss elastic modulus (G ") are measured. The test piece measures an adhesive layer or double-sided adhesive tape to a thickness of about 2 mm, and pinches between parallel disks.

The thickness of the pressure-sensitive adhesive layer used in the present invention is easy to ensure adhesion to the adherend, rework aptitude and re-peelability even when using a thin tape, so that the thickness of one side is preferably 10 to 100 µm, and 30 It is more preferable that it is -80 micrometers.

Although it does not specifically limit as a peeling sheet used for this invention, On at least one side of base materials, such as synthetic resin films, such as polyethylene, a polypropylene, and a polyester film, paper, a nonwoven fabric, cloth, a foam sheet, a metal foil, and these laminate bodies, And the thing which peeling process, such as a silicone type process, a long chain alkyl type process, and a fluorine type process for improving peelability from an adhesive, is given can be illustrated.

Especially, the peeling sheet in which the silicone type peeling process is given to the paper which laminated | stacked polyethylene, and the single side | surface of a polyester film is preferable.

[Double Sided Adhesive Tape]

By using the said foam base material and an adhesive layer, the double-sided adhesive tape of this invention shows favorable adhesiveness with a to-be-adhered body, and it is hard to produce the interlayer breakage of a foam base material, and an adhesive remains on the surface of a component even when an interlayer crack occurs. Since it can be peeled off easily, it is necessary to peel (rework) the double-sided adhesive tape or parts that failed to be bonded from the processed product at the time of manufacture of portable electronic devices, or to repair, regenerate, or reuse finished products such as portable electronic devices. In the case of separating, disassembling, or dismantling parts, the efficiency of the work of reattaching a new double-sided pressure-sensitive adhesive tape after removing the double-sided pressure-sensitive adhesive tape from the housing or parts, the yield of parts, and the recycling rate can be improved. In addition, in fixing the parts of an electronic device having a waterproof function, intrusion of water from the adhesion gap can be effectively prevented, and it has an excellent waterproof function.

As an embodiment of the double-sided adhesive tape of this invention, the structure which the adhesive layer was provided in the both surfaces of the said base material centering on a foam base material is made into a basic structure. The substrate and the pressure-sensitive adhesive layer may be directly laminated or may have other layers. What is necessary is just to select these aspects suitably according to a use use, and when providing dimensional stability and tensile strength to a tape further, laminate layers, such as a polyester film, and light-shielding layer, when providing a light shielding property to a tape, When securing the light reflection layer may be provided. When providing these other layers, a waterproof layer is used as the said other layer.

As the laminate layer, various resin films including a polyester film can be used. As these thickness, 1-16 micrometers is preferable and 3-12 micrometers is more preferable from the track | trackability of a foam base material.

As a light shielding layer, what is formed with the ink containing coloring agents, such as a pigment, is used conveniently, and since the layer which consists of black ink is excellent in light-shielding property, it is used preferably. As the reflective layer, a layer formed of white ink can be used simply. As thickness of these layers, 2-20 micrometers is preferable, and 4-6 micrometers is especially preferable. By making thickness into the said range, the curl of the base material by hardening shrinkage of an ink hardly arises, and the processability of a tape becomes favorable.

The double-sided adhesive tape of this invention can be manufactured by a well-known method. For example, after directly applying the acrylic pressure-sensitive adhesive composition to the foam base material or on the surface of another layer laminated on the foam base material, or applying the acrylic pressure-sensitive adhesive composition to the release sheet and drying it, the foam base material or The transfer method bonding to another layer surface is mentioned. Preferably, after apply | coating and drying an acrylic adhesive composition to a peeling sheet, it is a transfer method bonded together to a foam base material or another layer surface.

Although the thickness of the double-sided adhesive tape of this invention may be adjusted suitably according to the aspect to be used, it is 70-1400 micrometers. In the case of fixing a part of an electronic device, especially a small and thin portable electronic device, since a thin tape thickness is required, it is preferable that it is 100-600 micrometers, and it is especially preferable that it is 120 micrometers-500 micrometers. By making tape thickness into the said thickness, it can apply suitably also to thin and small portable electronic devices, and can implement favorable waterproofing function.

It is preferable that the surface adhesive strength 1 measured by the following measurement conditions of the double-sided adhesive tape of this invention is 100 N / 4cm <^2> or more, and it is more preferable that it is 130N / 4cm <^2> or more.

The measurement conditions of the said surface adhesion strength 1 are as follows.

1) At 23 ° C, two double-sided adhesive tapes having a width of 5 mm and a length of 4 cm are affixed in parallel to a 2 mm thick and 5 cm square acrylic plate.

2) Next, the acrylic plate with a double-sided adhesive tape produced in 1) was made into a rectangular flat ABS plate having a thickness of 2 mm and a 10 × 15 cm, having a hole having a diameter of 1 cm at the center, and the center of the acrylic plate and the ABS plate. It affixes so that this may match and pressurizes 1 round trip with a 2 kg roller, and it is left to stand at 23 degreeC for 1 hour, and it is set as a test piece.

3) Press the acrylic plate at 10 mm / min with the tensile tester which attached the stainless steel probe of diameter 8mm through the hole of the ABS board from the ABS side of a test piece, and measure the strength by which an acrylic plate peels.

Moreover, it is preferable that the surface adhesive strength 2 measured by the following measurement conditions of the double-sided adhesive tape of this invention is 250 mJ or more, and it is more preferable that it is 350 mJ or more.

The measurement conditions of the said surface adhesion strength 2 are as follows.

1) After cutting a double-sided adhesive tape at a 2 cm angle, it is affixed on the acrylic plate of thickness 2mm and a 2cm square.

2) The acryl plate with double-sided adhesive tape coincides with the polyamide plate (40 mass% glass fiber added) having a thickness of 2 mm and a 4 cm square with a hole having a diameter of 1 cm at the center, and the center of the acrylic plate and the center of the polyamide plate coincide. It adhere | attaches so that it may pressurize 1 round trip with a 2 kg roller, and it is left to stand at 23 degreeC for 24 hours, and is used as a test piece.

3) The test piece is placed on a stainless steel pedestal of 4 cm square, 3 cm long and 5 mm thick with the polyamide side up.

4) Through a hole on the polyamide side, a 100 mm-weight brass cone having a diameter of 5 mm and a protrusion of length 1 cm at the tip was continuously dropped (3 times per step) at 10 cm intervals to the test piece. Measure the height when the tape is peeled or broken.

5) From the measurement result, drop energy mJ (= 9.8 x height (m) x 100 g) is calculated.

The double-sided adhesive tape of this invention shows favorable adhesiveness with a to-be-adhered body, followability, rework aptitude, and repeelability even with a thin tape thickness. For this reason, in order to improve the yield at the time of manufacture of an electronic device or the like, the housing or parts are separated or removed in order to peel off (rework) double-sided adhesive tape or parts that have failed to be joined from the workpiece, or to repair, regenerate, or reuse the finished product. Also in the case of disassembly and disassembly, since the double-sided adhesive tape is easy to remove, it is to improve the reworking efficiency, the yield of a part or a product, and the recycling rate. As a specific use aspect, in electronic devices, such as an electronic notebook, a mobile telephone, a PHS, a camera, a music player, and a television, bonding of the protection panel and housing of an information display part, bonding of housings, a keypad of a housing, a sheet, and a touch panel It can be suitably used for bonding an input device such as an input device, bonding a housing and a decorative sheet, fixing other various members or modules, and the like.

Moreover, even if the thickness of a thin tape is double-sided adhesive tape of this invention, it shows favorable adhesiveness with a to-be-adhered body, can effectively prevent the invasion of water from an adhesion gap, and has the outstanding waterproof function. For this reason, the thinning progresses, the volume limitation in the housing is severe, and the waterproof function can be effectively provided even in a portable electronic device or the like which is difficult to provide a separate water-sealing means. As a specific use aspect, in portable electronic devices, such as an electronic notebook, a mobile telephone, a PHS, a camera, a music player, and a television, bonding of the protection panel of a information display part and a housing, bonding of housings, a housing, a sheet-like keypad, and a touch It can be used suitably for bonding input devices, such as a panel, bonding housing and a decorative sheet, fixing other various members, modules, etc. In addition, even in the parts where conventional water-sealing means such as rubber packing, gaskets and sealants are used, the waterproofing function can be effectively provided, and the housing and parts can be separated and repaired to repair, regenerate, or reuse the finished product. Easy to disassemble and dismantle

[Example]

(Preparation of Adhesive Solution A)

In a reaction vessel equipped with a stirrer, a reflux cooler, a thermometer, a dropping funnel, and a nitrogen gas inlet, 93.54 parts by mass of butyl acrylate, 3 parts by mass of vinyl acetate, 2.2 parts by mass of acrylic acid, and 1.2 parts by mass of N-vinyl-2-pyrrolidone Part, 0.06 parts by mass of 4-hydroxybutyl acrylate and 0.1 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator are dissolved in a solvent composed of 100 parts by mass of ethyl acetate, and polymerized at 60 ° C for 12 hours, The weight average molecular weight obtained the acrylic copolymer of 700,000 (polystyrene conversion). Next, with respect to 100 mass parts of acrylic copolymers, 15 mass parts of pencel D135 (pentaerythritol ester of a polymerized rosin, softening point 135 degreeC) by Arakawa Chemical Co., Ltd., and superester A100 (glycerol ester of disproportionated rosin) by Arakawa Chemical Co., Ltd. And 12 parts by mass of softening point 100 ° C. were added, ethyl acetate was added and mixed uniformly to obtain an adhesive solution A having a nonvolatile content of 40%.

(Preparation of Adhesive Solution B)

74.9 parts by mass of butyl acrylate, 20 parts by mass of 2-ethylhexyl acrylate, 2 parts by mass of acrylic acid, 3 parts by mass of vinyl acetate, in a reaction vessel equipped with a stirrer, a reflux cooler, a thermometer, a dropping funnel and a nitrogen gas inlet. 0.1 mass part of -hydroxybutyl acrylate and 0.1 mass part of 2,2'- azobisisobutyronitrile as a polymerization initiator are melt | dissolved in the solvent which consists of 100 mass parts of ethyl acetate, and it superposes | polymerizes at 70 degreeC for 12 hours, and a weight average molecular weight This 500,000 (polystyrene conversion) acrylic copolymer was obtained. Next, 25 mass parts of Pencel D135 by Arakawa Chemical Co., Ltd. was added with respect to 100 mass parts of acrylic copolymers, ethyl acetate was added and it mixed uniformly, and the adhesive solution B of 50% of non volatile matter was obtained.

Example 1

(Production of Double-sided Adhesive Tape)

PET film of 75 micrometers in thickness which carried out peeling process after adding 1.24 mass parts of "coronate L-45" (isocyanate type crosslinking agent, 45% of solid content) by Nippon Polyurethanes company, and stirring for 15 minutes with respect to 100 mass parts of said adhesive solutions A On it, it coated so that the thickness after drying might be 35 micrometers, and it dried at 80 degreeC for 3 minutes, and formed the adhesive layer.

Next, a white polyolefin-based foam (thickness: 130 μm, foam ratio 2.5 times, 25% compressive strength: 130 kPa, tensile modulus: 1140 N / cm ² , tensile strength 14.8 N / cm, surface corona treatment, wetness index 52 mN / m After bonding the said adhesive sheet one by one on both surfaces of (on the board | substrate), it laminated with the roll of linear pressure 5 kg / cm. Thereafter, the mixture was aged at 40 ° C. for 48 hours to obtain a double-sided adhesive sheet having a thickness of 200 μm.

[Examples 2 to 5]

The double-sided adhesive tape was obtained by the method similar to Example 1 except having used the foam base material of Table 1 instead of the white polyolefin foam, and changing the thickness after drying of the adhesive to the thickness shown in Table 1.

[Example 6]

A double-sided pressure-sensitive adhesive tape was prepared in the same manner as in Example 1 except that 0.8 parts by mass of `` coronate L-45 '' (isocyanate-based crosslinking agent, 45% solids) manufactured by Nippon Polyurethane Co., Ltd. was added to 100 parts by mass of the pressure-sensitive adhesive solution A. Got it.

[Example 7, 8]

The 75-micrometer-thick PET film which carried out peeling process after adding 2.0 mass parts of "coronate L-45" (isocyanate type crosslinking agent, 45% of solid content) made from Nippon Polyurethanes company, and stirring for 15 minutes with respect to 100 mass parts of said adhesive solutions B The double-sided adhesive tape was obtained by the method similar to Example 1 except having coated on it so that the thickness after drying might become the thickness shown in Table 1, and drying at 80 degreeC for 3 minutes, and forming the adhesive layer.

Example 9

Black ethylene-vinyl acetate-based foam instead of white polyolefin-based foam (thickness: 800 µm, foaming ratio 8 times, 25% compressive strength: 34 kPa, tensile strength: 24.8 N / cm, surface corona treatment, wetness index 52 mN / m The thickness which carried out peeling process after stirring for 15 minutes was added 2.0 mass parts of "coronate L-45" (isocyanate type crosslinking agent, 45% of solid content) made from Nippon Polyurethanes company with respect to 100 mass parts of adhesive solutions B on both surfaces of the The double-sided adhesive tape was obtained by the same method as Example 8 except having coated on 75 micrometers PET film so that the thickness after drying might be set to 50 micrometers, and it dried for 80 degreeC for 3 minutes, and formed the adhesive layer.

[Example 10]

(Preparation of Adhesive Solution F)

85.9 parts by mass of butyl acrylate, 4 parts by mass of acrylic acid, 10 parts by mass of methyl methacrylate, and 0.1 parts of 4-hydroxybutyl acrylate in a reaction vessel equipped with a stirrer, a reflux cooler, a thermometer, a dropping funnel, and a nitrogen gas inlet. In addition, 0.1 mass part of 2,2'- azobisisobutyronitrile is melt | dissolved in the solvent which consists of 100 mass parts of ethyl acetate as a polymerization initiator, it superposes | polymerizes at 60 degreeC for 12 hours, and the weight average molecular weight is 700,000 (polystyrene conversion) of An acrylic copolymer was obtained. Next, with respect to 100 mass parts of acrylic copolymers, the acrylic resin which consists of 10 mass parts of pencel D160 (pentaerythritol ester of a polymerized rosin), 97 mass parts of cyclohexyl methacrylates, and 3 mass parts of acrylic acid by Arakawa Chemical Co., Ltd. (weight average) 10 mass parts of molecular weights: 6000 and glass transition temperature: 66 degreeC) were added, ethyl acetate was added, it mixed uniformly, and the adhesive solution F of 30% of non volatile matter was obtained.

(Production of Double-sided Adhesive Tape)

PET film of 75 micrometers in thickness which carried out peeling process after adding 0.9 mass part of "Coronate L-45" (isocyanate type crosslinking agent, 45% of solid content) made from Nippon Polyurethane company, and stirring for 15 minutes with respect to 100 mass parts of said adhesive solutions F On both sides, it coated so that thickness after drying might be 35 micrometers, and it dried at 80 degreeC for 3 minutes, and formed the adhesive layer in the same way as Example 1, and obtained the double-sided adhesive tape.

Example 11

(Preparation of Adhesive Solution G)

71.9 parts by mass of butyl acrylate, 20 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of acrylic acid, 3 parts by mass of methyl acrylate in a reaction vessel equipped with a stirrer, a reflux cooler, a thermometer, a dropping funnel and a nitrogen gas inlet; 0.1 mass part of 2-hydroxyethyl acrylate and 0.1 mass part of 2,2'- azobisisobutyronitrile as a polymerization initiator are melt | dissolved in the solvent which consists of 100 mass parts of ethyl acetate, and they superpose | polymerize at 70 degreeC for 12 hours, and weight average The molecular weight obtained the acrylic copolymer of 600,000 (polystyrene conversion). Next, 20 parts by mass of Pencel D135 (pentaerythritol ester of a polymerized rosin) manufactured by Arakawa Chemical Co., Ltd., 10 parts by mass of T160 (terpene phenol) manufactured by Yashara Chemical Co., Ltd. were added to 100 parts by mass of the acrylic copolymer, and ethyl acetate was added to give uniformity. Mixing was carried out so as to obtain an adhesive solution G having a nonvolatile content of 45%.

(Production of Double-sided Adhesive Tape)

The 75-micrometer-thick PET film which carried out peeling process after adding 1.2 mass parts of "coronate L-45" (isocyanate type crosslinking agent, 45% of solid content) by Nippon Polyurethanes company, and stirring for 15 minutes with respect to 100 mass parts of said adhesive solutions G On both sides, it coated so that thickness after drying might be 35 micrometers, and it dried at 80 degreeC for 3 minutes, and formed the adhesive layer in the same way as Example 1, and obtained the double-sided adhesive tape.

[Comparative Examples 1 and 2]

The double-sided adhesive tape was obtained by the same method as Example 1 except having used the foam base material of Table 2 instead of the white polyolefin foam.

[Comparative Example 3]

A non-woven fabric (a basis weight: 17 g / m ² , tensile strength: 16.0 N / cm) was used instead of the white polyolefin-based foam, and both surfaces were prepared in the same manner as in Example 1 except that the thickness after drying of the pressure-sensitive adhesive was 70 µm. An adhesive sheet was obtained.

[Comparative Example 4]

Instead of the white polyolefin foam, the thickness after drying of an adhesive was used using the film made from polyethylene terephthalate (PET) (thickness: 100 micrometers, tensile strength: 210 N / cm, the surface was made into wetness index 52 mN / m by corona treatment). Except having used the thing of the table | surface, the double-sided adhesive sheet was obtained by the method similar to Example 1.

Comparative Example 5

(Preparation of Adhesive Solution C)

In a reaction vessel equipped with a stirrer, a reflux cooler, a thermometer, a dropping funnel, and a nitrogen gas inlet, 93.54 parts by mass of butyl acrylate, 3 parts by mass of vinyl acetate, 2.2 parts by mass of acrylic acid, and 1.2 parts by mass of N-vinyl-2-pyrrolidone Part, 0.06 parts by mass of 4-hydroxybutyl acrylate and 0.1 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator are dissolved in a solvent composed of 100 parts by mass of ethyl acetate, and polymerized at 60 ° C for 12 hours, The weight average molecular weight obtained the acrylic copolymer of 700,000 (polystyrene conversion). Next, 25 mass parts of super ester A100 by Arakawa Chemical Co., Ltd. was added to 100 mass parts of acryl-type copolymers, ethyl acetate was added, it mixed uniformly, and the adhesive solution C of 40% of non volatile matter was obtained.

(Production of Double-sided Adhesive Tape)

PET film of 75 micrometers in thickness which carried out peeling process after adding 1.0 mass part of "Coronate L-45" (isocyanate type crosslinking agent, 45% of solid content) made from Nippon Polyurethane company, and stirring for 15 minutes with respect to 100 mass parts of said adhesive solutions C On both sides, it coated so that thickness after drying might be 35 micrometers, and it dried at 80 degreeC for 3 minutes, and formed the adhesive layer in the same way as Example 1, and obtained the double-sided adhesive tape.

Comparative Example 6

(Preparation of Adhesive Solution D)

97.9 parts by mass of butyl acrylate, 2.0 parts by mass of acrylic acid, 0.1 parts by mass of 4-hydroxybutyl acrylate, and 2,2 as polymerization initiators in a reaction vessel equipped with a stirrer, a reflux cooler, a thermometer, a dropping funnel and a nitrogen gas inlet. 0.1 mass part of "-azobisisobutyronitrile was melt | dissolved in the solvent which consists of 100 mass parts of ethyl acetate, and superposed | polymerized at 70 degreeC for 12 hours, and the weight average molecular weight obtained the acrylic copolymer of 800,000 (polystyrene conversion). Next, ethyl acetate was added and mixed uniformly, and the adhesive solution D of 30% of non volatile matter was obtained.

(Production of Double-sided Adhesive Tape)

To 100 mass parts of adhesive solution D, 2.5 mass parts of "coronate L-45" (isocyanate type crosslinking agent, 45% of solid content) made from Nippon Polyurethane Co., Ltd. were added, and after stirring for 15 minutes, it peeled on the PET film of thickness 75micrometer. Coating was carried out so that the thickness after drying might be 50 micrometers, and it dried at 80 degreeC for 3 minutes, and formed the adhesive layer in the same manner as Example 1, and obtained the double-sided adhesive tape.

Comparative Example 7

(Preparation of Adhesive Solution E)

In a reaction vessel equipped with a stirrer, a reflux cooler, a thermometer, a dropping funnel and a nitrogen gas inlet, 98 parts by mass of 2-ethylhexyl acrylate, 1 part by mass of acrylic acid, 1 part by mass of 4-hydroxybutyl acrylate, and a polymerization initiator 0.1 mass part of 2,2'- azobisisobutyronitrile was melt | dissolved in the solvent which consists of 100 mass parts of ethyl acetate, and it superposed | polymerized at 70 degreeC for 12 hours, and obtained the acrylic copolymer of 800,000 (polystyrene conversion) by weight average molecular weight. . Ethyl acetate was added and uniformly mixed to obtain an adhesive solution E having a nonvolatile content of 30%.

(Production of Double-sided Adhesive Tape)

To 100 mass parts of pressure-sensitive adhesive solution E, 1.8 mass parts of "Coronate L-45" (isocyanate-based crosslinking agent, solid content 45%) manufactured by Nippon Polyurethane Co., Ltd. was added and stirred for 15 minutes, followed by peeling treatment on a PET film having a thickness of 75 μm. Coating was carried out so that the thickness after drying might be 50 micrometers, and it dried at 80 degreeC for 3 minutes, and formed the adhesive layer in the same manner as Example 1, and obtained the double-sided adhesive tape.

The following evaluation was performed about the foam base material used by the said Example and the comparative example, and the double-sided adhesive tape obtained by the said Example and the comparative example. The obtained results are shown in Tables 1-3.

[Defoam base material and double-sided adhesive tape thickness]

It was measured by dial tickness gauge G type made by Ozaki Seisakusho. In the case of a double-sided adhesive tape, it measured after peeling off a peeling film.

[Interlayer Strength of Foam Base Material]

To 100 parts by mass of the pressure-sensitive adhesive solution C, 1.1 parts by mass of `` coronate L-45 '' (isocyanate-based crosslinking agent, 45% solids) manufactured by Nippon Polyurethane Co., Ltd. was added and stirred for 15 minutes, followed by peeling treatment on a PET film having a thickness of 75 μm. Coating was carried out so that the thickness after drying might be 50 µm, and dried at 80 ° C. for 3 minutes to form an adhesive layer. Next, after bonding the said adhesive layer one by one on both surfaces of the foam which evaluates an interlaminar strength, it laminated with the roll of linear pressure 5kgf / cm. Then, it aged at 40 degreeC for 48 hours and produced the double-sided adhesive tape for interlayer strength measurement.

Next, a 2 kg roller 1 having a width of 2 cm and a length of 10 cm (the flow direction of the foam base material) obtained by contacting the adhesive side on one side with a polyethylene terephthalate film having a thickness of 25 μm on a stainless steel plate at 23 ° C. under 50% RH was used. It affixes by pressure in reciprocation, and is left to stand at 40 degreeC for 48 hours. After standing at 23 ° C. for 24 hours, the strength (N / cm) when the foam was torn (substrate destroyed) in the 90 ° direction at a tensile rate of 300 mm / min under 23 ° C. 50% RH was measured.

[Tensile modulus, tensile strength]

The maximum strength was measured when the foam base material or double-sided adhesive sheet (the peeling film was peeled off) processed on a test piece of 2 cm (the flow direction of the foam base material) and a width of 1 cm was cut at a tensile rate of 300 mm / min. did.

[Average bubble diameter in flow direction and width direction of foam base material]

The foam base material was cut in the width direction and the flow direction in 1 cm, and the cut surface center portion of the cut foam base material was enlarged by 50 times with a scanning electron microscope (SEM) (manufactured by Hitachi Seisakusho, S-2380N), and then The cross section of the width direction or the flow direction of the foam base material was photographed so that a cut surface may enter into a photograph over the full length of the base material thickness direction. In the obtained photograph, all the bubble diameters which existed in the cutting surface for 2 mm for the actual length before expansion of a flow direction or the width direction were measured, and the average bubble diameter was computed from the average value.

[Average bubble diameter in thickness direction of foam base material]

The thickness of the foam base material photographed by SEM was measured, and SEM photographing was performed on the conditions similar to the average bubble diameter measurement of the flow direction of a foam base material. In the obtained photograph, the number of bubbles of the thickness direction which exists in arbitrary places of a foam base material was visually counted, and the average bubble diameter of the thickness direction was computed from the following formula | equation.

Average bubble diameter (micrometer) in thickness direction = thickness (micrometer) of foam base material / number of bubbles

This was measured at three arbitrary places and made the average value into the average bubble diameter in the thickness direction.

[Adhesion strength 1]

1) At 23 ° C., two double-sided adhesive tapes of 5 mm in width and 4 cm in length are affixed in parallel to an acryl plate (Mitsubishi Rayon Co., Ltd.), acrylic light MR200 (trade name), color: transparent, at a thickness of 2 mm and 5 cm. .

2) Next, an acrylic plate with a double-sided adhesive tape made in 1) was formed on a rectangular ABS plate (Takiron, color: natural, no fine wrinkles) having a thickness of 2 mm and a 10 × 15 cm hole having a diameter of 1 cm at the center. After affixing so that the center of an acryl board and the center of an ABS board may correspond, it pressurizes 1 round trip with a 2 kg roller, it is left to stand at 23 degreeC for 1 hour, and it is set as a test piece.

3) The acrylic plate was pressed at 10 mm / min with the tensile tester which attached the stainless steel probe of diameter 8mm through the hole of the ABS board from the ABS side of the test piece, and the strength which an acrylic plate peels off was measured.

[Adhesion strength 2]

1) After cutting a double-sided adhesive tape at a 2 cm angle, it is affixed on an acrylic plate of 2 mm thickness and 2 cm square.

2) The acrylic plate with a double-sided adhesive sheet is acrylic on a 2 mm thick, 4 cm polyamide plate (Vittice Engineering Plastics Co., Ltd. Lenny "trade name", 40 wt% glass fiber added) with a hole of diameter 1 cm in the center. It is affixed so that the center of a plate and the center of a polyamide plate may correspond, and it presses 1 round trip with a 2 kg roller, and it is left to stand at 23 degreeC for 24 hours, and is used as a test piece.

3) The test piece is placed on a stainless steel pedestal of 4 cm square, 3 cm long and 5 mm thick with the polyamide side up.

4) Through a hole on the polyamide side, a 100 mm-weight brass cone having a diameter of 5 mm and a protrusion of length 1 cm at the tip was continuously dropped (3 times per step) at 10 cm intervals to the test piece. Measure the height when the tape is peeled or broken. Moreover, when there was no peeling of a tape or a fracture in the test piece after the test of height 70cm, a test was complete there and it was set to "686 <."

5) The drop energy mJ (= 9.8 x height (m) x 100 g) was calculated from the measurement results.

[Rework Aptitude]

1) A double-sided adhesive tape was produced with a liquid-shaped sample of 65 mm x 43 mm in width and 2 mm in width, and an acrylic plate of 2 mm in thickness and 65 mm x 45 mm in appearance (Mitsubishi Rayon Co., Ltd. Color: transparent, same as below). Next, it was attached to an ABS plate (Takiron Co., Ltd., color: natural, no fine wrinkles, the same below) having a thickness of 2 mm and an appearance of 90 mm × 50 mm, pressurized for 1 round trip with a 2 kg roller, and left at 23 ° C. for 24 hours. do.

2) Evaluate the state of the tape at the time of pulling out an acrylic plate in 23 degreeC in a vertical direction in a test piece.

3) Next, the ease of peeling when the double-sided adhesive tape which remained in ABS or an acryl plate was pulled off by the peeling angle about 135 degree direction by hand was evaluated.

(Double-circle): It was able to peel off without the interlayer cracking and looseness of a base material.

(Circle): The foam base material was split in the interlayer, but when the remaining double-sided adhesive tape was pulled out by hand, it peeled without looseness.

×: The glue remained on the adherend, or the foam base material was split between the layers, and then the remaining double-sided adhesive tape could not be peeled off even by pulling by hand.

Re-peelability

1) A double-sided adhesive tape is produced with a liquid-shaped sample having an outer shape of 65 mm x 43 mm and a width of 2 mm, and affixed to an acrylic plate having a thickness of 2 mm and an outer shape of 65 mm x 45 mm. Next, it is affixed to an ABS plate of thickness 2mm and an outline 90mm x 50mm, pressurized 1 round trip with a 2kg roller, and left to stand at 23 degreeC for 24 hours.

2) Next, it is left to stand in 60 degreeC 90% RH for 7 days, and it is set as the test piece in the environment of 23 degreeC 50% RH.

3) The state of the tape at the time of pulling out an acrylic board in a vertical direction and peeling off a test piece in 23 degreeC is evaluated.

4) Next, the ease of peeling when the double-sided adhesive tape which remained in ABS or an acryl board was pulled off at 135 degree of peeling angles, and peeled off was evaluated.

(Double-circle): There was no interlayer cracking of foam base material, and it peeled off after it loosened.

(Circle): The foam base material cracked in the interlayer, but when it pulled out the remaining double-sided adhesive tape, it peeled off without loosening.

X: Exposed to adherend, or the foam base material was split between layers, and even if it pulled the remaining double-sided adhesive tape by hand, it could not be peeled off

[Followability test]

1) A double-sided adhesive tape is cut | disconnected to width 1cm and length 5cm, affixed to the center part of the width direction of the acrylic plate of thickness 2mm, width 2cm x length 5cm, and produces the acrylic plate with a double-sided adhesive tape (FIG. 1).

2) Next, 2 sheets of polyethylene terephthalate-based adhesive tapes each having a thickness of 20 μm, a width of 5 mm, and a length of 2 cm are placed at the center of an acrylic plate having a thickness of 2 mm and a width of 2 cm x 5 cm at 1 cm intervals in the width direction. It affixes in parallel and produces the stepped acrylic board (FIG. 2).

3) After placing the acrylic plate with a double-sided adhesive tape on the adhesive tape part of the stepped acrylic plate at 23 degreeC, it pressurizes 1 round trip with a 2 kg roller from an edge part (FIG. 3).

4) From the acryl plate side which is stepped, the following state of the double-sided adhesive tape in step vicinity is visually evaluated.

○: The double-sided adhesive tape is in close contact with the stepped acrylic plate

×: The double-sided adhesive tape does not adhere to the acrylic plate with the step difference near the step

[Waterproof Test 1]

1) A double-sided adhesive tape was produced with a liquid-shaped sample having an outer shape of 65 mm x 45 mm and a width of 2 mm, and affixed to an acrylic plate having a thickness of 2 mm and an outer shape of 65 mm x 45 mm, and then attached to an ABS plate having a thickness of 2 mm and an outer shape of 65 mm x 45 mm. , Pressurized 1 round trip with a 2kg roller, it is left for 24 hours at 23 ℃ to be a test piece.

2) The test piece was immersed in a 5 mass% surfactant solution (produced by dipping P & G Co., Ltd.) with tap water at 10 ° C. for 10 minutes and then taken out and left for 10 minutes, and then immersed in the solution. The presence or absence of the inundation in the inside was evaluated.

○: no immersion

×: Inundation

[Waterproof Test 2]

1) A double-sided adhesive tape was prepared with a liquid-shaped sample having an outer shape of 65 mm x 45 mm and a width of 2 mm, and affixed to an acrylic plate having a thickness of 2 mm and an outer shape of 65 mm x 45 mm, and then to the center of an ABS plate having a thickness of 2 mm and an outer shape of 150 mm x 100 mm. It affixes (FIG. 4). After pressurizing 1 round trip with a 2kg roller, it was left at 23 ° C for 24 hours to prepare a test piece.

2) At a temperature of 23 ° C, a 150 mm long, 100 mm wide and 45 mm high コ -shaped measuring table (5 mm thick aluminum) is installed on the pedestal of the DuPont impact tester (manufactured by Tester Sangyo Co., Ltd.). The test piece was put down the acrylic plate (FIG. 5). A 25 mm diameter and 300 g mass made of stainless steel is dropped from the ABS plate side from a height of 30 cm, and the center portion of the ABS plate is subjected to impact five times at intervals of 10 seconds (Fig. 6). In addition, when an acrylic plate fell out under impact, the test was completed there.

3) After 10 minutes of immersion in a 5 mass% surfactant solution (produced by diluting P & G Joy) with tap water at 23 ° C. (prepared by tap water) at 10 ° C. The presence or absence of immersion in liquid smoke at the time was evaluated.

◎: No immersion, no change in appearance of foam

(Circle): There is no immersion, but the microscopic thermal image was recognized in a part of foam layer.

X: The acrylic plate fell out at the stage of the flooding or dropping impact

[Confidentiality Test]

1) A double-sided adhesive tape was prepared with a liquid sample of 5 cm x 4 cm in width and 2 mm in width, and affixed to a perforated acrylic plate having a thickness of 2 mm, an outer shape of 5 cm x 5 cm and a diameter of 3 mm in the center, and then thickness 3 mm, It sticks to the center part of the rectangular acrylic board of external shape 7cm * 5cm (FIG. 7). After pressurizing 1 round trip with a 2kg roller, it was left at 23 ° C for 24 hours to prepare a test piece.

2) At 23 ° C., a pressure of 0.02 MPa is applied from the perforated acrylic plate with nitrogen gas (FIG. 8).

3) The time until nitrogen leaked was measured from the tape part on a window frame.

TABLE 1

TABLE 2

[Table 3]

Like the said Examples 1-9, it was clear that the double-sided adhesive tape of this invention is compatible with the outstanding adhesiveness with a to-be-adhered body, rework suitability, and repeelability. Moreover, the double-sided adhesive tape of Examples 10-11 had favorable adhesiveness with the outstanding adhesiveness and rework aptitude. On the other hand, since the double-sided adhesive tape of the comparative example 1 had low interlayer strength and tensile strength of a foam base material, it was difficult to peel off the double-sided adhesive tape at the time of rework and re-peeling at the time of practical use. In addition, since neither of the double-sided adhesive tapes of Comparative Examples 2-4 was inferior in followability, immersion was confirmed in the waterproof test and the waterproof property could not be realized. In Comparative Example 5, the double-sided adhesive tape was difficult to peel off during rework and re-peeling. In Comparative Examples 6 and 7, neither had low adhesive strengths and realized waterproofness.

One… Double sided adhesive tape
2… Acrylic plate
3 ... Adhesive tape for step
4… Point to evaluate followability
5... ABS plate
6... A place of excitement
7 ... Drop impact
8… 'コ' shaped measuring table
9 ... Perforated Acrylic Plate
10... 3mm thick acrylic plate
11 ... Nitrogen inlet tube
12... nitrogen

Claims (11)

A double-sided adhesive tape having an adhesive layer on both sides of a foam base material, wherein the interlayer strength of the foam base material is 12 N / cm or more and 25% compressive strength is 30 to 170 kPa, and the pressure sensitive adhesive layer has 4 to 12 carbon atoms. A double-sided adhesive tape comprising an acrylic copolymer having a (meth) acrylate and a vinyl monomer having a carboxy group as a monomer component and a polymerization rosin ester-based tackifying resin. The method of claim 1,
The double-sided adhesive tape whose tensile elasticity modulus of the said foam base material is 200 N / cm <^2> or more, and the tensile strength per unit width is 10 N / cm or more. The method according to claim 1 or 2,
The double-sided adhesive tape whose average bubble diameter of the thickness direction of the said foam base material is 1-200 micrometers, and the average bubble diameter of a flow direction and the width direction is 1.2-700 micrometers. The method of claim 3,
The double-sided adhesive tape whose ratio of the average bubble diameter of the flow direction with respect to the average bubble diameter of the thickness direction of the said foam base material is 1.2-15, and the ratio of the average bubble diameter of the width direction with respect to the average bubble diameter of the thickness direction is 1.2-15. The method according to claim 1 or 2,
The double-sided adhesive tape whose said foam base material is a polyolefin foam base material. The method according to claim 1 or 2,
The double-sided adhesive tape containing 10-40 mass parts of said polymerization rosin ester tackifying resins with respect to 100 mass parts of said acrylic copolymers. The method according to claim 1 or 2,
The said acrylic copolymer contains the vinyl monomer which has a tertiary amide frame | skeleton in a molecule | numerator as a monomer component. The method according to claim 1 or 2,
Double-coated adhesive tape used to hold parts in electronic equipment that can be recycled or reused. The method according to claim 1 or 2,
The said foam base material is a foam which consists of independent bubbles, and is a double-sided adhesive tape used for fixing parts of an electronic device which has a waterproof function. The method according to claim 1 or 2,
The double-sided adhesive tape whose temperature which shows the maximum value of loss tangent in the dynamic-viscoelastic spectrum at the frequency of 1 Hz of the said adhesive layer is -30-10 degreeC. The method of claim 10,
The double-sided adhesive tape whose temperature which shows the maximum value of loss tangent in the dynamic-viscoelastic spectrum at the frequency of 1 Hz of the said double-sided adhesive tape is -30-20 degreeC, and whose maximum value of the loss tangent is 1.0 or less.

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