WO2007075771A1

WO2007075771A1 - Peelable adhesive tape and article-attaching kit

Info

Publication number: WO2007075771A1
Application number: PCT/US2006/048581
Authority: WO
Inventors: Yasuo Sudo
Original assignee: 3M Innovative Properties Company
Priority date: 2005-12-21
Filing date: 2006-12-20
Publication date: 2007-07-05
Also published as: AU2006331753A1; JP2007169421A; EP1963452A4; CA2634396A1; EP1963452A1; CN101346446A

Abstract

To provide an adhesive tape which can be stretched so as to be easily removed entirely from an adherend through one time of a pulling operation, leaving the adhesive little on the adherend, lending itself well to be stuck to various materials inclusive of a soft vinyl chloride, and can be strongly adhered even to adherends having a rugged structure in the surface thereof following up the shape to a sufficient degree. The adhesive tape comprises a pair of a first adhesive element having a first adhesive layer directly applied to an adherend and a second adhesive element, capable of being stretched, including a second adhesive layer applied to the adherend via the first adhesive layer and a base member that supports the second adhesive layer, wherein the first adhesive layer has the strain and stress smaller than the strain and stress of the second adhesive element as measured by a tensile test.

Description

PEELABLE ADHESIVE TAPE AND ARTICLE-ATTACHING KIT

Background

This invention relates to an adhesive tape. More specifically, the invention relates to a peelable adhesive tape which after having been stuck to a material or adherend can, as required, be easily removed from the material without leaving any adhesive on the material, without giving any substantial damage to the material, and which can further be applied to any material inclusive of soft vinyl chloride, following up even the material having a rugged structure in the surface so as to be strongly adhered thereto. The invention further relates to an article-attaching kit having the adhesive tape.

A variety of types of adhesive films and adhesive tabs or so-called adhesive tapes have been proposed and put into practical use to meet diversified objects. As an adhesive tape featuring peeling property, for example, there has, in recent years, been put into practical use an adhesive tape that can be stretched and removed without damaging the adhered material.

International Patent Publication (Kohyo) No. 6-504077 is disclosing an adhesive tape including a back lining and a pressure-sensitive adhesive carried on at least one main surface thereof, the back lining having a breaking elongation of 150% to 1200% in the lengthwise direction, an elastic recovery of smaller than 50% after stretched and a Young's modulus of at least 175.8 kg/cm² (2500 psi) but smaller than 5097 kg/cm (72,500 psi), the tape being capable of strongly bonded to the base member (material referred to in the invention) and removed from the surface of the base member when pulled at an angle of not larger than 35°, and the back lining having a breaking tensile strength large enough to be not broken in removing the tape from the surface of the base member. This adhesive tape has already been put into practical use and is commercially available, for example, as

COMMAND™ HOOK from 3M Co.

German Patent Laid-Open Publication No. 3331016 is disclosing a peelable adhesive tape using a thermoplastic rubber such as a styrene/butadiene block copolymer and an adhesive-forming resin such as a rosin derivative as base materials, the adhesive tape having a high rubbery elasticity and a low plasticity, having an adhering force which is smaller than a cohesive force, having a holding force which suitably decreases as the tape extends, having a ratio of the peeling strength to the tensile strength of 1 :2 or greater, and the bonding of the adhesive produced by the tape being eliminated in the direction of the surface of adhesion as the adhesive tape is stretched. When applied to a vinyl chloride-type wall paper including a plasticizer, however, this adhesive tape develops a problem in that the plasticizer migrates into the adhesive of the tape causing both the adhering force and the cohesive force to decrease, and becomes no longer usable.

There have further been proposed many adhesive tapes suited for sticking together the soft vinyl chloride films containing a plasticizer in large amounts.

Japanese Unexamined Patent Publication (Kokai) No. 5-302070) discloses an ornamental film obtained by applying or laminating, on the film surface, an adhesive agent which contains 0.005 to 0.1 part by weight of a crosslinking agent per 100 parts by weight of a copolymer having a weight average molecular weight of 700,000 to 1,200,000 obtained by copolymerizing 64 to 75% by weight of a (meth)acrylic acid ester having a C4 to C8 alkyl group, 20 to 26% by weight of a methyl methacrylate and 5 to 10% by weight of an acrylic acid.

Japanese Unexamined Patent Publication (Kokai) No. 8-311414 discloses an acrylic adhesive tape forming a multiplicity of adhesive layers, the exposed adhesive layer being an adhesive comprising chiefly a copolymer of 100 parts by weight of an alkyl (meth)acrylate ester monomer and 1 to 10 parts by weight of a nitrogen-containing (meth)acrylic monomer, and the adhesive layer continuous thereto being an adhesive comprising chiefly a copolymer of an alkyl (meth)acrylate ester. In the case of this adhesive tape, there has been reported that both the initial adhering force and the cohesive force exhibit sufficiently large values which in cooperation exhibit very excellent adhering performance without permitting the plasticizer to migrate into the vinyl chloride resin and, particularly, into the plasticized vinyl chloride resin. The present inventors therefore have used the adhesive proposed above for the pressure-sensitive adhesive of the adhesive tape disclosed in the above patent document 1. With the adhesive tape using the above adhesive, however, there occurs a problem in that when the adhesive tape is peeled and removed from the adhered material, the paste remains on the adhered material due to insufficient cohesive force of the adhesive and the adhered material is damaged due to a large adhering force. Summary

As described above, there have already been known a variety of types of adhesive tapes featuring pealing performance, some of them being commercially available. To meet diversified needs in recent years, however, it has been desired that the peelable adhesive tape can be adhered to any material or adherend, that when the adhesive tape is stuck to the material containing a plasticizer, the plasticizer does not migrate to the adhesive to deteriorate the cohesive force or the adhering force, that the peeling performance is not adversely affected due to the loss of balance between the cohesive force and the adhering force, that the residue such as the adhesive does not remain, and that the adhesive tape can be strongly stuck to the material even when it has a rugged structure in surfaces thereof.

The present invention provides a peelable adhesive tape which, after stuck to a material, can be stretched so as to be easily removed entirely therefrom through one time of a pulling operation, leaves the adhesive little on the material, suppresses damage to the material, can be stuck to various materials inclusive of a soft vinyl chloride, and can be strongly adhered not only to a material having a flat surface but also to a material having a rugged structure in the surface thereof following up the shape to a sufficient degree, as well as to provide an article-attaching kit equipped with the adhesive tape.

According to the present invention, the above is achieved by a peelable adhesive tape used being stuck to a material or adherend, comprising a pair of: a first adhesive element having a first adhesive layer directly applied to the material; and a second adhesive element, capable of being stretched, including a second adhesive layer applied to the material via the first adhesive layer and a base member that supports the second adhesive layer; wherein the first adhesive layer has the strain and stress smaller than the strain and stress of the second adhesive element as measured by a tensile testing.

According to another aspect of the present invention, there is further provided an article-attaching kit for attaching an article to a material via an adhesive layer, and having a peelable adhesive tape of the invention in combination with an article that is attached and fixed to the material via the first and second adhesive layers of the adhesive tape, wherein when the article is to be removed, as required, after it has been attached, the adhesive tape and the first and second adhesive layers are removed together with the article from the material.

As will be understood from the following detailed description, according to the present invention there can be provided a peelable adhesive tape which can be, say,

"stretch-released", which, after having been stuck to a material, can be removed therefrom by being stretched. In particular, the adhesive agent of the invention can be stuck to various materials inclusive of a soft vinyl chloride, can be strongly adhered not only to a material having a flat surface but also to a material having a rugged structure in the surface thereof following up the shape to a sufficient degree, and can be easily removed as a whole from the material through one time of pulling operation leaving the adhesive little and suppressing damage to the adhered material.

The invention further provides an article-attaching kit equipped with the adhesive tape of the invention. As described above, the present invention resides in:

(1) A peelable adhesive tape used being stuck to a material, which, particularly, can be "stretch-released", comprising a pair of: a first adhesive element having a first adhesive layer directly applied to the material; and a second adhesive element that can be stretched including a second adhesive layer applied to the material via the first adhesive layer and a base member (which may be omitted) that supports the second adhesive layer; and

(2) An article-attaching kit equipped with the adhesive tape of the invention. The invention will now be described with reference to the accompanying drawings.

Brief Description of Drawings

Fig. 1 is a sectional view illustrating a preferred embodiment of an adhesive tape according to the present invention.

Fig. 2 is a sectional view illustrating a preferred embodiment of a second adhesive element of the adhesive tape according to the present invention. Fig. 3 is a sectional view illustrating another preferred embodiment of the second adhesive element of the adhesive tape according to the present invention.

Figs. 4A-4C show sectional views illustrating a method of using the adhesive tape according to the present invention. Fig. 5 is a sectional view illustrating a preferred embodiment of an adhesive structure according to the present invention.

Fig. 6 is a perspective view illustrating a preferred embodiment of a material set according to the present invention.

Fig. 7 is a sectional view illustrating a method of testing the holding performance according to the embodiment.

Detailed Description

Fig. 1 is a sectional view illustrating a preferred embodiment of the adhesive of the present invention. As shown, a peelable adhesive tape 10 is constituted by a pair of a first adhesive element 10-1 having a first adhesive layer 3 directly applied to a material or adherend (not shown) and a second adhesive element 10-2. The second adhesive element 10-2 has a stretchable base member 1 carrying on one surface thereof a second adhesive layer 2 of an adhesive composition. As will be described later, 4a, 4b and 14 denote peeling papers which will be peeled off when the adhesive tape is to be used. The base member 1 is stretchable. Therefore, the adhesive tape 10 that is to be peeled again from the adhered material can be stretched to a suitable degree without adversely affecting the action and effect of the invention. The base member 1 in the illustrated embodiment is a single layer. As required, however, the base member 1 may of a multi-layer structure of two or more layers, and may be used as a composite base member or a laminated base member. The base member 1 has no second adhesive layer 2 at an end Ia thereof. This is for efficiently conducting the pulling operation for stretching by using the end Ia as a tab. As required, the second adhesive layer 2 may not be formed but, instead, a separately formed tab or the like piece of tape may be attached to the end of the base member 1. In the illustrated embodiment, the second adhesive layer 2 is applied to the one surface only of the base member 1. As will be described below, however, the second adhesive layer 2 may be formed on both surfaces of the base member depending upon the use of the adhesive tape. The base member having the adhesive layers applied on both surfaces thereof is suited for attaching any article to the material.

In the practice of the invention, as required, the base member may not be used but, instead, the surface of the second adhesive layer may be protected, and the second adhesive layer may be temporarily supported by protection means that can be peeled off the adhesive tape at the time of sticking the adhesive tape. Suitable protection means is, for example, a peeling paper described below as "peeling layer". If the protection means such as the peeling layer has a suitable thickness and a strength, the adhesive tape without the base member can be attached in the same manner as the one having the base member and, besides, the thickness of the obtained adhered structure can be decreased, and the gap can be decreased between the article and the material to which the article is attached.

In addition to using the two adhesive elements each having an adhesive layer in a pair, the adhesive tape of the present invention has a feature in that the first adhesive layer 3 that is to be joined to the material exhibits a stress lower than the strain and the stress of the adhesive tape 10 as a whole when the strain and stress are measured by the tensile test. The first and second adhesive layers 3 and 2 may comprise the same adhesive composition or different adhesive compositions. From the standpoint of adjusting the stress, however, it is recommended to form the first and second adhesive layers 3 and 2 by using different adhesive compositions. It is further desired that the first and second adhesive layers 3 and 2 have compositions and thickneses that can be stretched to meet the stretch of the base member. Details of the adhesive compositions will be described below.

Desirably, further, the first and second adhesive layers 3 and 2 can be removed together with the base member 1 when the adhesive tape 10 of the invention is stretched and peeled by being pulled at an angle of not larger than 35° from the surface of the adhered material.

In peeling the adhesive tape from the surface of the material while stretching it, further, it is desired that the adhering force that is measured is smaller than the breaking stress that is measured when the adhesive tape is subjected to the tensile testing. More desirably, the adhering force of when the adhesive tape is stretched and peeled from the surface of the material, is smaller than the breaking stress of when the adhesive tape is subjected to the tensile test and is 1/1.5 times thereof or smaller. In the adhesive tape 10 of the present invention, the surfaces where the adhesive layers are exposed of the adhesive elements, i.e., the adhesive surfaces of the first adhesive layer 3 and of the second adhesive layer 2 are protected by being covered with peeling papers called herein "peeling layers" (or often called release liners or peeling liners) 14a, 14b and 4. The peeling papers are effective means for protecting the adhesive surfaces as well as for enhancing the preservability and handling of the adhesive tape.

The adhesive tape of Fig. 1 can be used in order shown in, for example, Fig. 4. In Fig. 4, the second adhesive element 10-2 is the one obtained by applying the adhesive layers 2a and 2b onto both surfaces of the base member 1. Referring, first, to Fig. 4(A), a material to be adhered is prepared. The material that is shown comprises, for example, a wall member 51 of an aluminum plate and a wall paper 52 of vinyl chloride having fine a rugged structure in the surface thereof.

Referring next to Fig. 4(B), the peeling papers 14a and 14b are removed from the first adhesive element 10-1, and the first adhesive layer 3 is stuck to the wall paper 52 of the material. Immediately after the first adhesive layer 3 is stuck to the wall paper 52 or after a while, the second adhesive element 10-2 is laminated and stuck onto the first adhesive layer 3 on the wall paper 52.

The second adhesive element 10-2 may be stuck in a manner that it is stuck to an article 53 (hook for the wall paper, here) as shown in Fig 4(C), or the second adhesive element 10-2 only may be stuck. That is, the second adhesive element 10-2 is stuck to the article 53 via the third adhesive layer 2a and, then, the article 53 is pushed onto the wall paper 52 via the second adhesive layer 2b and is laminated thereon. Or₅ the second adhesive element 10-2 may be stuck to the wall paper 52 via the first adhesive layer 3 and, then, the article 53 may be stuck onto the third adhesive layer 2a. The first adhesive layer 3 is, first, stuck onto the surface of the material 52. Even when the surface of the material 52 is rugged, the first adhesive layer 3 follows the ruggedness to accomplish a substantially wide adhering area. This further enhances the adhering force of the adhesive tape 10 as a whole to the material. The operation for sticking the adhesive tape can be carried out relying upon a technique that has widely been employed for sticking the adhesive tapes. As required, a jig may be used in combination. Next, described below is the operation for removing the adhesive tape from the adhered material. First, a tab Ia at the end of the adhesive tape 10 is nipped by fingertips and is pulled with a suitable force in the direction of peeling. The angle for pulling the adhesive tape is, usually, not larger than about 35 degrees from the direction substantially in parallel with the surface of the adhesive tape. The angle for pulling the adhesive tape is desirably smaller than about 30 degrees and, more desirably, smaller than about 10 degrees. In the initial step of pulling, the resistance is great, first, for the shearing force of the adhesive tape. The base member of the adhesive tape starts deforming when a sufficiently large force is applied to overcome the resistance. Accompanying the deformation of the base member, the adhesive layer starts stretching and is directed. As a result, the base member breaks down, the sectional area decreases and, hence, is stiffened in the direction of stretch. The stiffening effect, next, shifts the stress to the interface between the adhesive tape and the material, whereby the adhesive tape starts peeling from the material. The adhesive layer remains adhered on the adhesive tape that is peeled, and there is observed no adhesive that is left on the material. Further, the step of peeling is not substantially accompanied by the three-dimensional stress, and the adhesive layers are not transformed into filaments.

In the adhesive tape 10 of the embodiment of this invention, further, the strain and the stress of the first adhesive layer 3 as measured by the tensile testing are lower than the strain and stress of the adhesive tape 10. By pulling the tab Ia of the adhesive tape, therefore, the first adhesive layer 3, the second adhesive layers 2a, 2b and the base member 1 can be peeled off integrally together at one time.

Here, the peeling of the highly stretched adhesive tape at a low angle is characterized by the growth of cracks of a "sharp" type. As represented by the fracture of a vitreous material, sharp cracks work to highly concentrate the stress at the ends of cracks (where the stress extinguishes) of small volumes in the adhesive composition. Due to a high concentration of stress at the ends of the cracks, there occurs a so-called brittle cleavage fracture of the adhesive composition. Typically, this fracture occurs accompanied by a small force (small amount of energy extinguishing in the adhesive composition) and obviously takes place on the interface. At larger peeling angles, i.e., when the angle is greater than 35 degrees, on the other hand, the base member of the adhesive tape does not stretch, and the adhesive composition turns into filaments thereof and is fractured cohesively. As represented by the fracture of a vitreous material, the growth of "blunt" cracks takes place following the crazing. In this model, filaments observed in the adhesive composition occur as a mechanism for extinguishing the energy like crazing fibrils seen in the vitreous material. Resistance against the peeling increases with an increase in energy that is extinguished, and an increased force is required for peeling the adhesive tape. As the volume of the material increases, the extinction of energy increases and the stress is not so concentrated as above. Therefore, the filaments of the adhesive composition are fractured cohesively as could not be avoided with the conventional technology, and the residue of the adhesive composition remains on the surface of the material. Otherwise, the surface of the material is damaged. Concerning the above feature, reference should be made to the description of International Patent Publication (Kohyo)No. 6-504077 (described above) if necessary. The adhesive tape of the present invention is not limited to the adhesive tapes 10 shown in Figs. 1 and 4 only but can be varied and improved within the scope of the present invention such as omitting the base member, improving the base member and applying the adhesive layers to both surfaces. For example, the second adhesive element 10-2 may have a base member 1 comprising two kinds of sheet-like support members 11 and 12 as shown in Fig. 2. Here, the sheet-like support members 11 and 12 can be constituted by using various base members so far as they do not spoil the action and effect of the invention. For instance, the sheet-like support member 11 is constituted by using a foamed plastic film, and the sheet-like support member 12 integrally laminated thereon is constituted by using another kind of polymer film, e.g., non-foamed polymer film (in other words, solid polymer film). The second adhesive layer 2 is applied onto one surface of the base member 1 as shown. Further, a tab Ia is formed at an end of the base member 1. Further, the second adhesive layer 2 is covered with a peeling paper which in this invention is called "peeling layer" (or is, often, called release liner or peel liner) for protection. The adhesive tape provided with the second adhesive element can be advantageously used for attaching and fixing, onto a wall surface which is the material to be adhered, a sheet-like article such as a calendar, a poster, a film or the like. Further, the material to be adhered such as the wall surface is, usually, provided with the adhesive tape to constitute a structure to be adhered.

Fig. 3 illustrates an example in which the second adhesive element 10-2 is constituted by a double-sided adhesive tape. As shown, the base member 1 includes a sheet-like support member 11, and sheet-like support members 12a and 12b integrally laminated on both surfaces thereof. The sheet-like support members 12a and 12b may or may not have the same composition and the thickness. Further, the sheet-like support members 12a and 12b are, usually, constituted by using a material different from that of the sheet-like support member 11. For example, the sheet-like support member 11 is constituted by a foamed polymer film, and both sides thereof are integrally sandwiched with the sheet-like support members 12a and 12b of solid polymer films. A multi-layered structure of four or more layers may be applied to the base member 1 , as a matter of course. Adhesive layers 2a and 2b of a predetermined adhesive composition have been applied to both sides of the base member 1. Here, the adhesive layer 2b corresponds to the second adhesive layer referred to in the invention, and the adhesive layer 2a corresponds to the third adhesive layer referred to in the invention. A tab Ia is formed at an end of the base member 1. Further, the second adhesive layer 2b and the third adhesive layer 2a are covered with peeling papers 4b and 4a which, in this invention, are referred to as the "peeling layers" for protecting the adhesive surfaces. The adhesive tape equipped with the second adhesive element can be advantageously used for mounting an article such as a hook on the wall surface. The material such as the wall surface is, usually, provided with the adhesive tape to constitute a structure for adhesion.

Fig. 5 is a view schematically illustrating an example where the adhesive tape equipped with the second adhesive element of Fig. 3 is stuck to the wall paper, and an article is attached to the wall paper. The wall paper 52 is made of a vinyl chloride resin, has a fine rugged structure in the surface thereof, and is stuck to a wall member 51 of a stainless steel. As described earlier with reference to Fig. 3, the adhesive tape that is shown has a second adhesive element of a base member 1 having surfaces facing the third adhesive layer 2a and the second adhesive layer 2b and, further, has a first adhesive element with the first adhesive layer 3. The adhesive tape completes the structure 20 for adhesion upon laminating the second adhesive element after the first adhesive layer 3 has been stuck to the wall paper 52. Further, an article 53 is mounted on the wall paper 52 (wall member 51) via the adhesive tape. The adhering force of the adhesive tape is so strong that the article 53 does not peel off the wall member 51.

To remove the article 53 from the wall member 51 , the tab Ia is pulled to peel the adhesive tape together with the article 53 off the wall paper 52 in a manner as described above. According to the present invention, the second adhesive layer 2b and the first adhesive layer 3 are so combined together as to satisfy a particular relationship of stress. Therefore, the adhesive tape that is strongly bonded to the wall paper 52 can be easily peeled off by being pulled with a weak force without leaving the adhesive on the wall paper 52.

As described above, the peelable adhesive tape of the present invention includes the pair of the first and second adhesive elements as constituent elements and, further, includes a substitute for the base material, a third adhesive layer and a peeling layer as constituent elements. These constituent elements will now be concretely described. The adhesive tape of the present invention may not often use the base member depending upon the cases, but generally uses, as a main member, a stretchable base material or, on other words, a base member which can be stretched at a predetermined stretching ratio when it is pulled in the lengthwise direction thereof. The base member used for producing the adhesive tape is, preferably, a highly stretchable polymer film. Here, "highly stretchable" stands for a property which produces the stretching of at least about 150% on the basis of the initial length when the adhesive tape (base member) is stretched in the lengthwise direction. The base member used in the embodiment of the present invention can be varied depending upon the use of the adhesive tape but, usually, produces the stretching of about 50 to about 1,200%. When the stretching ratio of the base member is smaller than 50%, the stretch-release effect of the invention is no longer obtained. Conversely, when the stretching ratio of the base member exceeds 1,200%, it becomes difficult to peel the adhesive tape off the material at a good timing. The base member is capable of producing the stretching which is, desirably, about 150 to about 700% and, more preferably, .about 350 to about 700%. The highly stretchable polymer film that can be used as the base member includes various polymer films, and, desirably, includes the below-mentioned polymer films (1) to (4) in one kind or in any combination of two or more kinds, as the base member of the tape.

(1) A polymer film having a breaking elongation of about 50 to about 1,200% in the lengthwise direction, an elasticity recovery of smaller than about 50% after stretched and a Young's modulus of about 1 ,000 to about 72,500 psi (i.e., about 6,894.7 to 499,865.8 KPa)(first polymer film);

(2) A foamed polymer film (second polymer film);

(3) A polymer film having an yield stress or a proportional critical stress of not larger than about 20 N/15 mm, a tensile breaking strength of not smaller than about 30 N/15 mm, and a breaking elongation of not smaller than about 150% (third polymer film); and

(4) A polymer film containing a thermoplastic rubber and an adhesive-forming resin (fourth polymer film).

When these or other polymer films are used in a combination of two or more kinds, it is desired that the polymer films as a whole are used being integrally bonded together in the form of a composite film or a laminated film. There is no particular limitation on the method of integrating the polymer films, and there can be exemplified a simultaneous forming, a junction with an adhesive and a junction by pressing.

If described in further detail, the polymer films (1) to (4) are as described below. The compositions and constitutions of the polymer films can be applied to other polymer films, too, unless stated otherwise.

The first polymer film is a highly stretchable polymer film having a breaking elongation in the lengthwise direction of about 50 to about 1 ,200%, preferably, about 150 to 700% and, more preferably, about 350 to 700%, an elasticity recovery after stretched of smaller than about 50%, preferably, smaller than about 30% and, more preferably, smaller than about 20%, and a Young's modulus of at least about 1,000 psi (about 6,894.7 KPa), preferably, about 2,500 psi (about 17,236.8 KPa) and, more preferably, at least about 3,000 psi (about 20,684.1 KPa) but not larger than about 72,500 psi (about 499,865.8 KPa), preferably, not larger than about 50,000 psi (about 344,753 KPa) and, more preferably, about 5,000 to about 30,000 psi (about 34,473.5 to about 206,841 KPa). When the polymer film has a too high Young's modulus, it becomes very difficult to stretch the adhesive tape to a degree large enough for accomplishing a smart peeling. When the Young's modulus is too low, the adhesive tape loses the plasticity and becomes rubbery. The breaking elongation of the base member must be so high that the base member is not broken before the tape is removed from the surface of the material to which the adhesive tape has been adhered. The breaking elongation of the base member is, preferably, at least about 4,000 psi (about 27,578.8 KPa)₃ more preferably, at least about 5,300 psi (about 36,541.9 KPa) and, most preferably, at least about 6,300 psi (about 43,436.6 KPa).

Though not limited thereto only, representative examples of the material that can be preferably used for the polymer film include polyolefins such as polyethylene, high- density polyethylene, low-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene, polypropylene and polybutylene; vinyl copolymers such as polyvinyl chloride (including both of those that have been plasticized and those that have not been plasticized) and polyvinyl acetate; olefinic copolymers such as ethylene/methacrylate copolymer, ethylene/vinyl acetate copolymer, acrylonitrile/butadiene/styrene copolymer and ethylene/propylene copolymer; acrylic polymer and copolymer; and mixtures thereof. There can be further arbitrarily used plastic or plastic and elastic materials, such as polypropylene/polyethylene, polyurethane/polyolefin, polyurethane/polycarbonate, polyurethane/polyester, and the like. These polymer films can be a single-layer or a multi-layer film, a non-woven film, a porous film, or a foamed film, or a combination thereof. The polymer film may, further, be made of a filler-containing material, i.e., may be a filler-containing film, such as the one made of a polyolefϊn containing calcium carbonate. The polymer film is, preferably, selected from polyethylene and polypropylene films, and the most desired material is linear low-density and ultra-low-density polyethylene film's. The above polymer can be produced by any known film-forming method, such as extrusion method, simultaneous extrusion method, solvent casting method, foaming method or felt-forming method.

The polymer film may have any thickness so far as it has a uniting property large enough for accomplishing the machining and handling and, preferably, has a thickness in a range of about 10 to about 250 μm. The polymer film having a thickness of not larger than 10 μm may not be capable of preventing the adhesive composition that is used from oozing out in case the adhesive composition has a property to ooze out, and is not desirable. Conversely, when the thickness of the polymer film exceeds 250 μtn, a stretching force higher than a desired force is, usually, required for peeling and removing the adhesive tape from the material, i.e., the removal becomes difficult. When the thickness lies within a preferred range, there exists a tendency that a thin polymer film can be removed more easily than the thick ones. Concerning the first polymer film, reference should be made to International Patent Publication No. 6-504077 (described earlier), if necessary.

The second polymer film is a foamed polymer film or, in other words, a layer or a film of polymer foam. Though not limited thereto only, representative examples of the foamed polymer film include polyolefins such as high-density polyethylene, low-density polyethylene, linear low-density polyethylene and linear ultra-low-density polyethylene; vinyl copolymers such as polyvinyl chloride (including both of those that have been plasticized and those that have not been plasticized) and polyvinyl acetate; olefinic copolymers such as ethylene/methacrylate copolymer, ethylene/vinyl acetate copolymer, acrylonitrile/butadiene/styrene copolymer and ethylene/propylene copolymer; acrylic polymer and acrylic copolymer; polyurethane; and combinations thereof. There can be used any plastic material or a mixture or a blend of plastic and elastomeric materials, such as polypropylene/polyethylene, polyurethane/polyolefin, polyurethane/polycarbonate, and polyurethane/polyester.

The foamed polymer film, usually, has a density of about 2 to about 30 lb./ft³ (about 32 to about 481 kg/m³). When lying within this density range, the foam of the polymer film is stretched, and the adhesive tape can be favorably peeled off the material.

Particularly preferred foamed polymer films are polyolefinic foamed films. Among such foamed polymer films, the most preferred ones are the polyolefϊn foams, trade names "Volextra (trademark)" and "Volara (trademark)" manufactured by Sekisui (U.S.A.) Co., Voltek Department, Massachusetts, U.S.A.

As required, there may be used a non-foaming film, i.e., a solid polymer film together with the foamed polymer film or, in a particular case, in its place. The above polymer film is desirably selected from polyethylene and polypropylene films. The most desired materials are linear low-density polyethylene film and linear ultra-low-density polyethylene film. A preferred polyethylene film is the one having a trade name "Maxilene (trademark) 200" manufactured by Consolidated Thermoplastics Co., Illinois, U.S.A.

The foamed polymer film may have any thickness so far as it can be worked and handled to a sufficient degree and that it imparts desired performance related to tensile properties for peeling the adhesive tape off the material. This thickness is, usually, in a range of about 10 to about 250 μm and, preferably, in a range of about 10 to about 150 μm. Concerning the second polymer film, reference should be made to International Patent Publication No. 9-502213, if necessary. The third polymer film is the one having a yield stress or a proportional critical stress of not larger than about 20 N/15 mm, a tensile breaking strength of not smaller than about 30 N/15 mm, and a breaking elongation of not smaller than about 150%. This polymer film is thin and has a high modulus of elasticity yet capable of being stretched to a sufficient degree with a low yielding force. When used as the base member of the tape, therefore, the adhesive tape can be peeled off without developing curls. The polymer film features the following properties: i.e., an yield stress or a proportional critical stress of not larger than about 20 N/15 mm irrespective of the thickness, a tensile breaking strength (breaking strength) of not smaller than about 30 N/15 mm at any thickness, and a breaking elongation (stretchability) in the lengthwise direction of not smaller than about 150% and, particularly, about 150 to about 1 ,500%.

In this polymer film, the modulus of elasticity thereof represents a stress in a portion of the base member that is stretched first. The stress that substantially accompanies the peeling by pulling is the sum of the yield stress or the proportional critical stress of the base member and the adhering force that is dependent upon the angle of pulling. By using a material having a sufficiently low yielding point or a proportional critical point, though it may have a high Young's modulus, in combination with a suitable adhesive composition, it is made possible to provide an adhesive tape having a tensile force that meets the user's demand. Besides, the material having a high Young's modulus also exhibits rigidity, and can be easily handled by the user. It is further desired that the polymer film exhibits an elasticity recovery after stretched of not larger than 50%. That is, in the case of the adhesive of the present invention, it is desired that the base member that is used loses the elasticity after it is stretched once by being pulled and peeled. By using the above polymer film which is highly stretchable and having a high breaking strength as a base member for producing the adhesive tape, there is obtained the adhesive tape which can be easily stretched when it is to be stretch-released without damaging the surface that is being adhered and without substantially leaving the adhesive after the adhesive tape has been released.

Though not limited thereto only, examples of the polymer that can be advantageously used for forming the polymer film include polyolefins such as high- density polyethylene HDPE), low-density polyethylene LDPE), linear low-density polyethylene (LLDPE), linear ultra-low-density polyethylene U-LLDPE) and polypropylene (PP); polyvinyl polymers such as polyvinyl chloride (PVC) and polyvinyl acetate (PVA); polyolefinic copolymers such as ethylene/methacrylic acid copolymer (EEMA), ethylene/vinyl acetate copolymer EVA); block copolymers such as acrylic polymer and styrene/isoprene/vinyl acetate copolymer; and various thermoplastic elastomers (TPE) such as polyolefins. The polymer film may be made from any one of these polymers or a mixture of two or more of these polymers.

The polymer film may be a single layer of the above polymer film or may be a composite film formed by integrally laminating two or more pieces of polymer films. In the latter case, the above polymer film may be included in at least any one of the layers of the composite film. In the case of the polymer film used in this invention, however, it is desired that the tensile strain is not larger than 10% relative to the specified stress of 2 MPa. This is effective in preventing the adhesive tape that is finished as a thin film from curling that is caused by the bending stress produced by its own back surface (when it is in a rolled state) or when it is taken out from the peeling paper. The above-mentioned polymer films can assume various forms. Suitable films may be, for example, a film of a non- woven fabric, a film of a woven fabric, a porous film and a foamed film. As required, films of different kinds may be used in combination as a single polymer film.

The thickness of the polymer film can be varied over a wide range depending upon the use but is, usually, in a range of about 10 to about 250 μm and, more preferably, in a range of about 30 to about 100 μm. When the thickness is smaller than 10 μm, the polymer film can no longer maintain a sufficient degree of tensile strength, and can no longer work as a base member for the adhesive tape. When the thickness exceeds 250 μm, on the other hand, the operation becomes substantially difficult to peel the adhesive tape off the material due to a high tensile strength, and the effect of forming the adhesive tape in a decreased thickness is lost.

The above polymer film can be produced by using a technique that has generally been employed for producing the polymer films. In the case of the polymer film of, for example, a composite structure, the starting polymers are simultaneously extruded from suitable dies, and are stretched to form the first and second polymer films. Further, the polymer films that have been formed in advance may be laminated and melt-adhered together. Depending upon the cases, the polymer films may be joined together by using an adhesive. Concerning the third polymer film, reference should be made to Japanese Unexamined Patent Publication No. 2002-167558, if necessary.

The fourth polymer film is the one containing a thermoplastic rubber and an adhesive-forming resin, i.e., a rubber/resin polymer film. Here, the rubber component is the one that has not been vulcanized and that imparts the required rubbery elasticity and cohesive force to the polymer film. As the thermoplastic rubber, there can be used, for example, a styrene/butadiene block copolymer and a styrene/isoprene block copolymer. On the other hand, the resin component is for realizing excellent adhesiveness to various materials. As the adhesive-forming resin, there can be used, for example, a natural or synthetic resin existing as an ester or a free acid, such as rosin derivative, terpene resin, terpene-phenol resin and synthetic petroleum resin. These resins may be hydrogenated, disproportionated or dimerized.

As required, the polymer film contains additives that have been generally used in the field of polymer films, such as antioxidant, ultraviolet ray stabilizer, coloring agent, etc.

The thickness of the polymer film can be varied over a wide range but is, generally, in a range of about 200 to about 600 μm.

The polymer film can be produced according to various methods. Usually, however, the polymer film is produced by dissolving the above-mentioned rubber component and the resin component in a solvent such as benzene, and applying the obtained highly concentrated solution onto a peeling paper or the like by using an applicator, followed by drying. As a simplified method, there can be exemplified the one in which a starting mixture is heated and blended, and is flow-stretched or extrusion- molded at a temperature of about 120 to about 160⁰C. Concerning the fourth polymer film, reference should be made to German Laid-Open Patent Publication No. 3331016 (described above), if necessary.

The above-mentioned polymer films and other polymer films useful as the base member in the embodiment of the present invention can be varied and improved within the scope of the present invention. For example, the polymer film may, as required, contain an organic or inorganic filler dispersed therein. As the organic filler, there can be exemplified a resin material different from the polymer constituting the polymer film. As the inorganic filler, further, there can be exemplified calcium carbonate, titanium oxide and silica. Such fillers are useful for further enhancing the rigidity of the film or for lowering the yield point to suppress the tensile force of the film. The organic or inorganic filler contained in the polymer film can possess various forms and sizes, preferably, such as spherical particles, needle-like crystals or like forms. The sizes thereof can be widely varied but are, usually, in a range of about 1 to about 20 μm. In the case of needle-like whiskers, for example, it is desired that the sizes are relatively fine, the length thereof being, preferably, in a range of about 1 to about 15 μm and, more preferably, about 10 μm. The needle-like whiskers have a diameter of, usually, about 0.1 μm. When the size of the filler used here is not larger than 1 μm, the filler must be used in large amounts to obtain the effect of adding the filler. When the size exceeds 20 μm, on the other hand, formation of the film and other desired effects are adversely affected. The above-mentioned filler can be contained in the polymer film in amounts over a wide range but is, usually, added in an amount over a range of, desirably, about 5 to about 50% by weight. When the filler is added in an amount smaller than 5% by weight, the effect of addition is not exhibited. Conversely, when the amount of addition exceeds 50% by weight, formation of the film and other desired effect may be adversely affected. Usually, it is desired that the filler is added in an amount of about 10% by weight. As required, further, the polymer film may be tinted in any color. Being tinted, the adhesive tape that is finally obtained exhibits improved appearance and handling. The tinted color may be a monotone or a combination of two or more kinds of colors for improving the design. Further, when the base member has a multi-layer structure, one or more pieces of polymer films constituting the base member may be arbitrarily tinted.

When the use as the base member of the adhesive tape is not adversely affected and when the additional action and effect can be expected, the polymer film may further incorporate other additional layers such as reinforcing layer, cushioning layer and parting layer that have been incorporated, as required, in the field of adhesive tapes. The base member of the adhesive tape may be a single layer of the above- mentioned polymer film or any other suitable polymer film, or may be a multi-layer structure or a composite structure of two or more layers. When used as the multi-layer structure, the polymer films of the same kind may be laminated or the polymer films of two or more kinds may be laminated in any combination. In either of these cases, the polymer films may be laminated on the surfaces of the multi-layer structure obtained by using materials of kinds different from the base member referred to in the invention, or may be inserted therein.

The base member can be used in any thickness depending upon the constitution and use of the adhesive tape but, usually, has a thickness in a range of about 10 μm to about 30 mm. When the thickness is smaller than 10 μm, the base member becomes too thin, and it becomes difficult to produce the adhesive tape and, besides, handling of the adhesive tape itself is deteriorated. Conversely, when the thickness of the base member is not smaller than 30 mm, the obtained adhesive tape becomes too thick, deteriorating the handling, increasing the cost of production, and limiting the use. Desirably, the base member has a thickness over a range of about 10 μm to about 10 mm.

The base member may be directly used or may further have an auxiliary adhesive layer on one surface thereof or on both surfaces thereof. That is, when the base member consists of a polymer film, it is desired that one surface or both surfaces of the polymer film are provided with an auxiliary adhesive layers of an adhesive of the type same as, or different from, the adhesive composition constituting the adhesive tape. Upon forming the auxiliary sticking layer on one or both surfaces of the base member, it is allowed to further enhance the effect of junction of the adhesive layer and the effect of preventing the adhesive from being left on the material and of preventing the occurrence of damage.

The base member may be provided with the auxiliary adhesive layer or the adhesive layer without at all treating the surfaces thereof. To enhance the effect of adhesion between the two, however, it is desired to effect the primer treatment in advance. As the primer treatment, there can be exemplified a corona discharge treatment, a plasma discharge treatment, a flame treatment, an electron beam irradiation, an ultraviolet ray irradiation and a primer coating.

The adhesive tape of the invention includes at least two adhesive layers, i.e., the first and second adhesive layers in combination with the above-mentioned base member or in the absence of the base member. These adhesive layers may comprise the same adhesive composition or different adhesive compositions. These adhesive layers are, usually, used on one surface of the base member. As required, however, an additional adhesive layer or a third adhesive layer may be provided on the surface on the opposite side of the base member. The first and second adhesive layers are used for sticking the adhesive tape onto the material, and the third sticking layer is used for attaching any article onto the material via the sticking layer.

The first adhesive layer, second adhesive layer, third adhesive layer and any other adhesive layer provided as required, can be formed by using various adhesive compositions suited for the adhesive layers. For instance, a first component having cohesive force (cohesive component) and a second component (basic component) can be used alone or in combination. In particular, it is advantageous to use the adhesive composition containing at least a mixture of two kinds of these components. The individual components will be described hereinbelow.

(1) First component.

The first component is a cohesive component. It is desired that the cohesive component contains a styrene-type block copolymer as a main component. The styrene- type block copolymer useful for putting the invention into practice may include a styrene/isoprene block copolymer, a styrene/butadiene block copolymer, a styrene/ethylene/propylene block copolymer, and a styrene/ethylene/butylene block copolymer.

The cohesive component can contain an adhesion-imparting agent in addition to the above-mentioned styrene-type block copolymer. Though not limited thereto only, suitable examples of the adhesion-imparting agent include a rosin resin, a rosin ester resin, a hydrogenated rosin ester resin, a terpene resin, a terpene phenol resin, a hydrogenated terpene resin, a petroleum resin, a hydrogenated petroleum resin, a chroman resin, a styrene resin, a modified styrene resin, a xylene resin and an epoxy resin.

As required, further, the first component can contain other additives. Suitable examples of the additives include a softening agent, an anti-aging agent, an ultraviolet ray absorber and the like. Examples of the softening agent include those agents of the paraffin type, naphthene type and phthalic ester type. As the anti-aging agent, there can be used anti-oxidants of the hindered phenol type or the hindered amine type.

(2) Second component.

The second component is a basic component. The basic component contains, as a chief component, a (meth)acrylic copolymer and, preferably, a nitrogen-containing (meth)acrylic copolymer. The nitrogen-containing (meth)acrylic copolymer can include copolymers of various types and is, desirably, a copolymer of a (meth)acrylic acid alkyl ester and a nitrogen-containing vinyl monomer.

The copolymer of the (meth)acrylic acid alkyl ester and the nitrogen-containing vinyl monomer can be prepared by copolymerizing the alkyl (meth)acrylate ester and the nitrogen-containing vinyl monomer at various mixing ratios. The copolymer, preferably, comprises about 45 to about 99.9 parts by weight of the alkyl (meth)acrylate ester and 0.1 to 20 parts by weight of the nitrogen-containing vinyl monomer. As required, further, the nitrogen-containing (meth)acrylic copolymer may be grafted with a polystyrene having a glass transition point of about 20 to 250⁰C and a weight average molecular weight of about 2,000 to 500,000 as measured by a gel permeation chromatography (GPC) in an amount of 0 to about 30 parts by weight. This is because, the solution of the mixed adhesive composition does not easily separate into upper and lower two layers in the molten state. As required, further, a vinyl monomer having a reactive functional group on a side chain may be copolymerized in an amount of about 0.1 to 5 parts by weight.

If concretely described, the alkyl (meth)acrylate ester that can be used for preparing the nitrogen-containing (meth)acrylic copolymer is, preferably, a (meth)acryic acid ester having an alkyl group with about 1 to about 11 carbon atoms. Though not limited thereto only, representative examples of the (meth)acrylic acid ester include methyl (meth)acrylate ester, ethyl (meth)acrylate ester, butyl (meth)acrylate ester, 2- methylbutyl (meth)acrylate ester, t-butyl (meth)acrylate ester, 2-ethylhexyl (meth)acrylate ester, isooctyl (meth)acrylate ester, cyclohexyl (meth)acrylate ester, and isoboronyl (meth)acrylate ester. These (meth)acrylic acid esters may be used alone or in a combination of two or more kinds.

The nitrogen-containing vinyl monomer is, preferably, a vinyl monomer having an amido group or a tertiary amino group. Though not limited thereto only, representative examples of the nitrogen-containing vinyl monomer include N,N-dimethylacrylamide, N- isopropylacrylamide, N,N-dimethylaminoethyl(meth)acrylate, N₅N- dimethylaminopropylacrylamide, 2-vinylpyridine, 4-vinylpyridine and 1-vinylimidazole. These nitrogen-containing vinyl monomers may be used alone or in a combination of two or more kinds.

The above nitrogen-containing vinyl monomer can be copolymerized at various ratios when being copolymerized with the alkyl (meth)acrylate ester but, usually, at a ratio of, preferably, about 0.1 to about 20 parts by weight. This is because, when the ratio of the vinyl monomer is smaller than 0.1 part by weight, the adhering force may become insufficient for the soft vinyl chloride which is the material to be adhered. When the ratio thereof exceeds 20 parts by weight, on the other hand, a (meth)acry late-type copolymer of a low molecular weight may be formed in the copolymerization of the second component.

In producing the nitrogen-containing (meth)acrylic copolymer according to the present invention, the (meth)acrylic copolymer can be grafted with the polystyrene. As a simple method of grafting, there can be exemplified a method of copolymerizing a styrene macromer. Details of the method of synthesizing the styrene macromer have been disclosed in Japanese Unexamined Patent Publication No. 59-75975 and are not described here. Further, the styrene macromer is commercially available as "MACROMONOMER- AS-6S" (trade name) from Toa Gosei Co. It is allowable to graft the polystyrene relying upon a method other than the above method, as a matter of course.

In preparing the nitrogen-containing (meth)acrylic copolymer, there is used a vinyl monomer having a reactive functional group on a side chain thereof. Though not limited thereto only, the vinyl monomer that can be used may be carboxyl group-containing vinyl monomers or acid anhydrides thereof, such as acrylic acid, methacrylic acid, itaconic acid and maleic acid, and hydroxyl group-containing vinyl monomers such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. The vinyl monomer having a polar group such as carboxyl group or hydroxyl group and the vinyl monomer having a photo-reacting group, such as acryloylbenzophenone, may impart a crosslinking reaction point to the (meth)acrylic resin composition.

Further, the crosslinking reaction may be induced with the crosslinking reaction point as a start point by using a crosslinking agent in combination. As the crosslinking agent, there can be used the one that is usually used in the chemistry of polymerization, such as polyfunctional epoxy compound, polyfunctional melamine compound, polyfunctional isocyanate compound, metallic crosslinking agent and polyfunctional aziridine compound. Or, the crosslinking reaction may be induced by using radiant rays such as UV and EB without using crosslinking agent.

In the adhesive composition used in forming the adhesive layer, the above first and second components can be mixed at various ratios, and there is no particular limitation on the mixing ratio. The mixing ratio of the first component and the second component is, usually, in a range of about 5:95 to about 95:5 (solid component ratio) and, preferably, in a range of about 25:75 to about 90:10. When the mixing ratio of the two components is within the above range, there is no problem such as the adhesive is left on the material or the material is damaged due to a large adhering force stemming from a very large cohesive force of the adhesive at the time when the adhesive tape is peeled and removed from the material. Even when the adhesive structure of the present invention is produced by sticking the adhesive tape onto a vinyl chloride-type sheet or a wall paper containing a plasticizer, it does not happen that the plasticizer migrates into the adhesive layer to greatly deteriorate the cohesive force or the adhering force of the adhesive tape. The second adhesive layer may be applied onto only one surface of the base member of the adhesive or onto both surfaces of the base member of the tape as second and third adhesive layers depending upon the use and constitution of the adhesive tape. In either case, the thickness of the adhesive layer can be varied over a wide range depending upon the use or constitution of the adhesive tape. The thickness of the adhesive layer is usually in a range of about 10 to about 1,000 μm, preferably, in a range of about 10 to about 400 μm and, more preferably, in a range of about 10 to about 200 μm. In this preferred range of thickness, a thick layer enables the adhesive tape to be easily removed as compared to a thin layer. This is symmetrical to an ordinary method of removing, such as a method of removing at a peeling angle of, for example, not smaller than 90 degrees. In general, a thick layer before being adhered tends to exhibit a large peeling force at a peeling angle of the adhesive tape of 180 degrees as compared to a thin layer. When the adhesive tape of the present invention is removed by stretching at a low angle of smaller than 35 degrees, the adhesive composition tends to be locked by the base member of the tape and is forced to stretch significantly. Under these conditions, the adhesive layer

(individual adhesive layers when there are many) undergoes the contraction to decrease the sectional area thereof. The sectional area of a thin adhesive layer, i.e., thickness x width, is smaller than that of a thick adhesive layer. Therefore, the stress or the force per a unit area becomes greater in a thin layer than in a thick layer. In practice, this makes the adhesive composition rigid. A layer having a large rigidity exhibits a high resistance against the deformation and, hence, a large force is needed for the peeling.

The adhesive tape typically uses a first adhesive layer of an adhesive composition different from the adhesive layer thereof in combination with the second adhesive layer of the second adhesive element. The first adhesive layer constitutes the first adhesive element and is, preferably, formed by using a rubber-type adhesive, an acrylic adhesive or a mixture thereof like the second adhesive layer (for details, see the above description related to the second adhesive layer). As required, further, these adhesive agents contain an adhesion-imparting agent and any other additives (see the description above). Though not limited thereto only, examples of the adhesive include rubber-type adhesives such as natural rubber, olefin polymer, silicone polymer, isoprene, polybutadiene, polyurethane, styrene/isoprene/styrene copolymer and styrene/butadiene block copolymer, and acrylic adhesives such as a copolymer of an acrylic acid ester of an alkyl with 4 to 16 carbon atoms and an acrylic acid, etc.

As described above, the first adhesive layer can be formed relying upon the same method as the one for forming the second adhesive layer and using the same adhesive composition. As a preferred example, when the material to be adhered is a wall paper of vinyl chloride, the adhesive composition is, advantageously, a mixture of (i) a resin composition using a styrene-type block copolymer as a chief member and (ii) a nitrogen- containing (meth)acrylic copolymer obtained by copolymerizing an alkyl (meth)acrylate ester or a derivative thereof with a nitrogen-containing vinyl monomer. Though there is no particular limitation, the mixing ratio of the components (i) and (ii) is, usually, in a range of (i):(ii) = 5:95 to 95:5 (solid component ratio) and, preferably, in a range of 25:75 to 90: 10.

When the first adhesive layer is measured for its strain and stress by the tensile test as described above, it is desired that the strain and stress that are measured are lower than a strain-stress curve by the tensile test of the second adhesive element having the second adhesive layer that is to be laminated on the first adhesive layer. This is because, when the tensile stress of the first adhesive layer is greater than that of the adhesive tape, the first adhesive layer cannot be simultaneously peeled off at the time when the adhesive tape is peeled off the material, and the first adhesive layer remains on the surface of the material after the adhesive tape is peeled off.

The thickness of the first adhesive layer can be varied over a wide range depending upon the use and constitution of the adhesive tape. The thickness of the adhesive layer is, usually, in a range of about 25 to about 3,000 μm, preferably, in a range of about 25 to about 400 μm and, more preferably, in a range of about 25 to about 200 μm. When the thickness of the first adhesive layer exceeds 3,000 μm, the pressing force exerted on the adhesive tape is dispersed when the adhesive tape is stuck to the material, whereby the adhesive tape fails to suitably follow up the rugged structure of the material. Besides, the pulling resistance becomes so great that the peeling operation by pulling becomes substantially impossible. When the adhesive tape having the first adhesive layer is to be pulled and peeled off the surface of the material while being stretched, the adhering force of the first adhesive layer to the material is smaller than the breaking stress of when the adhesive tape having the first adhesive layer is subjected to the tensile test. If concrete numerical values are described, the adhering force of when the first adhesive layer is to be pulled and peeled off the material is, typically, 1/1.5 or smaller and, preferably, 1/2.0 or smaller of the breaking stress of when the second adhesive element having the second adhesive layer is subjected to the tensile testing.

In the adhesive tape of the present invention, the total thickness of the first adhesive layer and the second adhesive layer can be varied over a wide range. Typically, the total thickness of these adhesive layers is in a range of about 25 to about 3,000 μm and, more preferably, in a range of about 50 to 1,000 μm. When the total thickness of the adhesive layers becomes not larger than 25 μm, the tensile breaking strength becomes substantially smaller than the adhering strength, and it becomes impossible to execute the peeling operation by pulling. Conversely, when the total thickness becomes greater than 3,000 μm, the tensile resistance becomes so great that the peeling operation by pulling cannot be executed.

In the adhesive tape and in the adhesive element of the present invention, the adhesive layers which are the uppermost layers, e.g., the first adhesive layer and the third adhesive layer, may be used in their own forms. It is, however, desired to use them after the adhesive surfaces of the adhesive layers have been covered, typically, with a peeling paper (also called peeling liner or release liner). Upon covering the adhesive layers with the peeling papers, the adhesive tape can be easily handled and rolled. As the peeling paper, there can be exemplified a paper or a plastic film treated with a silicone compound or the like compound for parting.

The adhesive tape according to the present invention can be produced according to any method that has heretofore been generally used for the production of pressure- sensitive adhesive tapes. For instance, the adhesive composition can be directly applied onto one or both surfaces of the base member. Or, the adhesive layer may be formed as a separate independent layer and may be laminated on the base member. As the method of application, there can be employed an ordinarily used method, such as knife-coating method, hot-melting method or the like method. In order to improve the adhesion of the adhesive layer on the base member, the surfaces of the base member may be treated with a primer prior to the step of coating or the step of lamination. Other pretreatment may be effected instead of the treatment with the primer. The pretreatment can be conducted by using a reactive chemical adhesion accelerator, such as hydroxyethyl acrylate, hydroxyethyl methacrylate or any other reactive species of a low molecular weight. The base member is made of a polymer film, and a corona discharge treatment is generally preferred.

The adhesive tape according to the present invention features an excellent balance between the adhering force and the cohesive force, and can be advantageously used for a variety of materials. It can be advantageously used for the wall paper, too. Attention can be given to that the adhesive tape is capable of solving great problems maintaining balance, such as mutual action to the vinyl chloride that constitutes the material thereof, preventing a drop in the adhering performance caused by the oozing of a plasticizer from the material, and performance that follows up various ruggedness in the surface which affects the appearance. The object for applying the adhesive tape of the invention is not limited to the vinyl chloride-type material only which contains a plasticizer but can also be applied to the materials of various types, such as a wall paper or a film having rugged patterns in the surface thereof to a conspicuous degree, a sheet, a mortar wall, a lysine-finished wall or a concrete wall, that have rugged patterns in the surfaces thereof to a conspicuous degree, and to the materials of which the surfaces have been roughly treated; Namely, the adhesive tape of the invention can be strongly stuck to the materials and can be peeled off without damaging the materials. Though not limited thereto only, the material in the form of a film which is suited for putting the invention into practice may be an ethylene/vinyl alcohol copolymer resin film and a styrene/(meth)acrylic copolymer resin film. The material to be adhered referred to here includes a vinyl chloride-type wall paper including a plasticizer that is described above.

The above noticeable effects are expected for the adhesive tape of the invention. Therefore, the adhesive tape can be advantageously applied to various materials ranging from soft articles through up to hard articles, and is capable of providing adhered structures having excellent properties. For instance, the adhesive tape of the present invention can be advantageously used in a multiplicity of technical fields including the following categories:

(1) Mounting use, such as mounting on a wall, forming a side portion of the body of an automobile, handle grip, etc.; (2) Indication use, such as road sign, marking for automobiles, traffic marking, reflection sheet, etc.;

(3) Coupling use, such as adhering two or more contains or boxes;

(4) Closing use, such as sealing a container, sealing a box, sealing a food or beverage container, sealing a diaper, sealing a surgical drape, etc.; (5) Removable labels, such as price label (price tag), indicator label on a container, etc.; and

(6) Medical use, such as bandage and the like.

As particularly useful examples, the adhesive tape of the present invention can be advantageously applied to a vinyl chloride-type material and, particularly, a material made of a vinyl chloride resin. The material to be adhered includes molded articles to which particular shapes have been imparted and any other articles. Preferred materials include, for example, a sheet, i.e., a sheet-like or film-like article and, particularly, a wall paper and the like articles. This is because these articles usually contain a plasticizer as represented by a vinyl chloride sheet. In the conventional adhesive tapes, therefore, the plasticizer is a serious cause of dropping the adhesiveness of the adhesive tape. In the case of the adhesive tape of the invention, when the adhesive sheet is stuck to a vinyl chloride sheet or any other similar sheet containing a plasticizer, it has been found that the adhesiveness is not adversely affected and the stretch-release performance is stably maintained, too. The adhesive tape of the present invention can be strongly stuck to the vinyl chloride-type wall paper that contains the plasticizer and can, further, be peeled off the wall paper without damaging the wall paper.

In addition, the present inventors have discovered that when the adhesive tape of the present invention is produced while improving the above-mentioned first component (cohesive component) and the second component (basic component), the adhesive tape can be advantageously applied even to the materials of various types having rugged patterns in the surfaces thereof to a conspicuous degree or of which the surfaces have been roughly treated, such as a wall paper, a sheet, a film, a mortar wall, a lysine-finished wall and a concrete wall. The adhesive tape of the present invention can not only be strongly stuck to the material having a conspicuous rigged pattern in the surface thereof but also be peeled off the material without damaging the material. The rugged pattern or the rugged structure referred to in the present invention includes various forms. When, for example, reference is made to the wall paper, there can be exemplified an emboss working pattern, a foamed emboss working pattern, a mesh pattern and a lattice pattern formed on the surfaces thereof.

That is, when a copolymer of an alkyl (meth)acrylate ester or a derivative thereof and a nitrogen-containing vinyl monomer is used as the nitrogen-containing (meth)acrylic copolymer that constitutes the second component and when the alkyl (meth)acrylate ester contains an isooctyl (meth)acrylate ester and a butyl (meth)acrylate ester, the adhesive tape of the present invention can be particularly advantageously applied to the conspicuously rugged wall papers. In recent years, in particular, there have been placed in the market many wall papers having diversified surface shapes from the standpoint of appearance inclusive of the wall papers having conspicuous ruggedness in the surface. Therefore, the adhesive tape of the present invention will find an increased probability of utilization.

The isooctyl (meth)acrylate ester and the butyl (meth)acrylate ester can be copolymerized together being used at various ratios and are, usually, used at a ratio of, desirably, about 80:20 to about 0:100.

In the adhesive tape of the invention, further, an elastomer having a conjugated double bond is further added to the styrene block copolymer used as the first component to improve the adhering force without lowering the cohesive force. Here, the elastomer having a conjugated double bond that is additionally used includes various elastomers but is, desirably, a polybutadiene, a polyisoprene or a combination thereof. It is desired that the elastomer has a high molecular weight which is, usually, in a range of about 1 ,000 to about 2,000,000 and, desirably, in a range of about 1,000 to about 1,000,000. When the elastomer of a high molecular weight is added to the cohesive component, a process oil may not be used. The adhesive tape of the present invention can be advantageously used even for the materials to be adhered made of various soft or hard materials, such as glass, ceramics, tile, plastics, concrete, lumber (coated lumber, laminated board, particle board), stone member and metal member. Further, the material to be adhered is in many cases used in places of an elevated temperature and an elevated humidity (in other "words, in a humid and hot environment) such as in kitchen and bathroom. Even when the adhesive tape of the invention is stuck to the material in such environments, the adhesiveness and stretch- release performance of the adhesive tape are not impaired.

The invention is further concerned with an article-attaching kit using the adhesive tape of the present invention. Fig. 6 is a diagram schematically illustrating an article- attaching kit of the invention. The article-attaching kit 30 that is shown is used for attaching a hook 53 which is an article to be attached to the wall member, and where the hook 53, the first adhesive element 10-1 and the second adhesive element 10-2 are placed on a support member (thick paper) 31 , and are fixed by being covered with a transparent plastic film (not shown). The first adhesive element 10-1 has its adhesive surface covered with a peeling paper 14b, and the second adhesive element 10-2 is covered with a peeling paper 4b. To attach the hook 53 onto the wall member, the hook 53 and the second adhesive element 10-2 are taken out from the kit 30, and the second adhesive element 10-2 is attached to the back side of the hook 53 via the third adhesive layer. Next, the hook 53 is stuck to the wall member and is fixed thereto via the second adhesive layer of the second adhesive element attached to the hook 53. The first adhesive layer of the first adhesive element 10-1 is transferred and stuck to the wall member in advance.

Or, the first adhesive layer of the first adhesive element 10-1 is stuck to the wall member in advance, the second adhesive element 10-2 is stuck alone thereon and, then, the hook 53 is attached to the wall member via the third adhesive layer.

To remove the hook 53 from the wall member, as required, the adhesive tape is simply pulled while holding the hook 53; i.e., the adhesive tape can be easily peeled off together with the hook 53 leaving no adhesive on the surface of the wall member. EXAMPLES

Next, the invention will be described with reference to Examples. Here, the invention is in no way limited to these Examples only, as a matter of course.

First, summarized below are abbreviations of starting substances used in the following preparation examples.

BA: Butyl acrylate (manufactured by Wako Junyaku Kogyo Co.).

AA: Acrylic acid (manufactured by Wako Junyaku Kogyo Co.).

Vim: 1-Vinylimidazole (manufactured by Tokyo Kasei Kogyo Co.).

EtOAc: Ethyl acetate (manufactured by Wako Junyaku Kogyo Co.). StyM: Styrene macromer having the following properties and structural formula prepared according to a method described in Japanese Unexamined Patent Publication (Kokai) No.

59-75975, page 14, right upper column, monomer "C-3",

(Properties) A solution containing 50% by weight of a methacrylate-terminated polystyrene/cyclohexane, Weight average molecular weight = 13 ,000 (based on GPC),

(Structural formula) CH₂=C(CH3)C(=O)-O-CH2CH2-(polystyrene)-CH₂CH₂CH₂CH3.

ADVN: 2,2'-Azobis(2,4-dimethylvaleronitrile)(azo-type polymerization initiator, manufactured by Wako Junyaku Kogyo Co.).

Finaprene™41 1 : Styrene/butadiene/styrene block copolymer (manufactured by Fina Oil and Chemical Co.).

Asaprene™1205: Styrene/butadiene block copolymer (manufactured by Asahi Kasei Co.).

Piccolyte™A-135: Adhesiveness-imparting agent (manufactured by Hercules Chemical

Co.).

Irganox™1330: Phenolic anti-oxidant (manufactured by Ciba Specialty Chemicals Co.). Shellflex™37 IN: Naphthene-type oil (manufactured by Shell Chemical Co.).

Preparation of Example 1

Preparation of an acrylic adhesive agent.

156 Grams of butyl acrylate, 22.5 g of 1-vinylimidazole, 1.13 g of acrylic acid and 90 g of styrene macromer were successively added into a 2000-ml separable flask. Next, 0.27 g of 2,2'-azobis(2,4-dimethylvaleronitrile) and 480 g of ethyl acetate were thrown therein. The polymerization was conducted in a constant-temperature water vessel maintained at 50⁰C for 8 hours while blowing a nitrogen gas from the lower portion of the blended solution by using a Pasteur pipette.

Preparation of Example 2

Preparation of a rubber-type adhesive agent.

A rubber-type adhesive agent having the following composition was prepared. Finaprene™411 65.0 parts by wei ght

Asaprene™ 1205 65.0 parts by weight Piccolyte™A-135 129.9 parts by weight

Irganox™ 1330 2.6 parts by weight

Shellflex™371N 6.6 parts by weight

Toluene 487.5 parts by weight

Production of Example 1

A double-sided adhesive tape with a pulling tab was prepared so as to be used as the second adhesive element in the production of the adhesive tape. The double-sided adhesive tape prepared here possessed the same constitution as the second adhesive element 10-2 of Fig. 3, and is commercially available as COMMAND™ TAB from Sumitomo 3M Co., Ltd.

The COMMAND™ TAB used here possessed the following layer constitution. Support member (core) 11 Foamed polyethylene film

Support member (surface layer) 12a Polyethylene film Support member (surface layer) 12b Polyethylene film Third adhesive layer 2a Rubber-type adhesive

Second adhesive layer 2b Rubber-type adhesive

Thickness (total) 950 μm

The individual adhesive layers are covered with a PET peeling liner. Production of Example 2

There were provided the following four kinds of transfer sheets with an adhesive layer for use as the first adhesive element in the production of the adhesive tapes.

Sample 1;

A double-sided adhesive tape commercially available from Sumitomo Three-M Co. as ultra-powerful double-sided tape (for glasses and acrylics). The adhesive layer was a copolymer of an isooctyl acrylate and an acrylic acid, and possessed a thickness of 1 ,000 μm. Sample 2;

The acrylic adhesive prepared in the Preparation Example 1 above and the rubber- type adhesive prepared in the Preparation Example 2 above were mixed together at a ratio of 3 :7, and the mixture was applied onto a PET peeling liner maintaining a thickness of 70 μm. For easy use, further, the adhesive layer that was formed was covered with another PET peeling liner.

Sample 3:

The rubber-type adhesive prepared in the Preparation Example 2 above was applied onto a PET peeling liner maintaining a thickness of 70 μm. For easy use, further, the adhesive layer that was formed was covered with another PET peeling liner.

Sample 4:

A double-sided adhesive tape commercially available from Sumitomo Three-M Co. as COMMAND™ TAB (see above). The adhesive layer was a rubber-type adhesive and possessed a thickness of 950 μm.

Example 1 (Reference Example).

Ah adhesive sheet same as the adhesive sheet of the invention was prepared but without using the first adhesive element (first adhesive layer) and was put to the tensile test and to the holding test. There was provided, as a material to be adhered, a wall paper of a vinyl chloride resin (trade name "SP9903", manufactured by Sangetsu Co.) which was emboss- worked on the surface thereof and having a thickness of 2.0 mm as shown in Fig. 7, which was, then, stuck to an aluminum plate 51 with an adhesive. Next, a double-sided adhesive tape (COMMAND™ TAB) prepared in the Preparation Example 1 was cut into a width of 16 mm and a length of 16 mm. The thus obtained double-sided sample adhesive tape 10 was stuck to the wall paper 52 after having removed the peeling liner therefrom.

Tensile Test: The aluminum plate 51 was mounted on the test device, and the double-sided sample adhesive tape 10 was press-adhered onto the wall paper 52 by rolling a 10-kg stainless steel roller one round trip. Next, by nipping the tab, the double-sided sample adhesive tape 10 was pulled at a peeling angle of 2° and a pulling rate of 300 mm/min. to peel it off the wall paper 52. The double-sided sample adhesive tape 10 was measured for its proportional limit, breaking point and breaking elongation to be 18 (N/ 15 mm), 44

(N/15 mm) and 750 (%), respectively, as shown in Table 1 below. The tensile strength has been converted into a width of 16 mm. After the tensile test, the wall paper was observed for its surface but there was recognized no adhesive that was remaining.

Holding Test:

After the double-sided sample adhesive tape 10 was stuck to the wall paper 52 as described above, a hook 53 made of a styrol resin was attached as shown in Fig. 7. The hook 53 used here was the COMMAND™ HOOK (M-size) manufactured by Sumitomo 3M Co., Ltd. in combination with the COMMAND™ TAB. After attached to the wall paper 52, the hook 53 was pressed with a static load of 10 kg for 30 seconds.

Next, a load W of 3.7 kg was hung from the hook 53. The time (minutes) for holding the hook 53 using the double-sided sample adhesive tape 10 was measured to be 472 minutes as shown in Table 1 appearing below. Example 2

The method described in Example 1 was repeated. In this Example, however, the first adhesive layer of the first adhesive element was transferred onto the wall paper prior to sticking the double-sided sample adhesive tape onto the wall paper. As described in Example 1, the wall paper 52 made of the vinyl chloride resin was stuck to the aluminum plate 51. Thereafter, the first adhesive layer (acrylic adhesive) was transferred onto a predetermined position of the wall paper 52 from the transfer sheet (sample 1) having the adhesive layer produced in the Production Example 2. The transferred first adhesive layer measured 16 mm wide (measured width of 18 mm) and 16 mm long. Next, the peeling liner was removed from the double-sided sample adhesive tape 10 that was obtained by cutting the double-sided adhesive tape provided in the Production Example 1 into 16 mm wide and 16 mm long. The double-sided sample adhesive tape 10 was stuck to the wall paper 52.

Tensile Test:

The aluminum plate 51 was mounted on the test device, and the double-sided sample adhesive tape 10 was press-adhered onto the wall paper 52 by rolling a 10-kg stainless steel roller one round trip. Next, by nipping the tab, the double-sided sample adhesive tape 10 was pulled at a peeling angle of 2° and a pulling rate of 300 mm/min. to peel it off the wall paper 52. The double-sided sample adhesive tape 10 was measured for its proportional limit, breaking point and breaking elongation to be 1.8 (N/15 mm), 16 (N/15 mm) and 850 (%), respectively, as shown in Table 1 below. After the tensile test, the wall paper was observed for its surface but there was recognized no adhesive that was remaining. Namely, in this Example, it was learned that both the first and second adhesive layers were favorably peeled off simultaneously.

Holding Test:

After the double-sided sample adhesive tape 10 was stuck to the wall paper 52 via the first adhesive layer (acrylic adhesive) as described above, a hook 53 made of a styrol resin was attached and was pressed with a static load of 10 kg for 30 seconds. Next, a load W of 3.7 kg was hung from the hook 53. The time (minutes) for holding the hook 53 using the double-sided sample adhesive tape 10 was measured to be 573 minutes as shown in Table 1 appearing below.

Example 3 The method described in Example 1 was repeated. In this Example, however, the first adhesive layer of the first adhesive element was transferred onto the wall paper before sticking the double-sided sample adhesive tape onto the wall paper.

As described in Example 1, the wall paper 52 made of the vinyl chloride resin was stuck to the aluminum plate 51. Thereafter, the first adhesive layer (rubber/acrylic blended adhesive) was transferred onto a predetermined position of the wall paper 52 from the transfer sheet (sample 2) having the adhesive layer produced in the Production Example 2. The transferred first adhesive layer measured 16 mm wide (measured width of 10 mm) and 16 mm long. Next, the peeling liner was removed from the double-sided sample adhesive tape 10 that was obtained by cutting the double-sided adhesive tape provided in the Production Example 1 into 16 mm wide and 16 mm long. The double- sided sample adhesive tape 10 was stuck to the wall paper 52.

Tensile Test:

The aluminum plate 51 was mounted on the test device, and the double-sided sample adhesive tape 10 was press-adhered onto the wall paper 52 by rolling a 10-kg stainless steel roller one round trip. Next, by nipping the tab, the double-sided sample adhesive tape 10 was pulled at a peeling angle of 2° and a pulling rate of 300 mm/min. to peel it off the wall paper 52. The double-sided sample adhesive tape 10 was measured for its proportional limit, breaking point and breaking elongation to be 0.64 (N/ 15 mm), 4 (N/ 15 mm) and 800 (%), respectively as shown in Table 1 below. After the tensile test, the wall paper was observed for its surface but there was recognized no adhesive that was remaining. Namely, in this Example, it was learned that both the first and second adhesive layers were favorably peeled off simultaneously. Holding Test:

After the double-sided sample adhesive tape 10 was stuck to the wall paper 52 via the first adhesive layer (rubber/acrylic blended adhesive) as described above, a hook 53 made of a styrol resin was attached and was pressed with a static load of 10 kg for 30 seconds. Next, a load W of 3.7 kg was hung from the hook 53. The time (minutes) for holding the hook 53 using the double-sided sample adhesive tape 10 was measured to be > 25,000 minutes as shown in Table 1 appearing below.

Example 4 The method described in Example 1 was repeated. In this Example, however, the first adhesive layer of the first adhesive element was transferred onto the wall paper before sticking the double-sided sample adhesive tape onto the wall paper.

As described in Example 1, the wall paper 52 made of the vinyl chloride resin was stuck to the aluminum plate 51. Thereafter, the first adhesive layer (rubber-type adhesive) was transferred onto a predetermined position of the wall paper 52 from the transfer sheet (sample 3) having the adhesive layer produced in the Production Example 2. The transferred first adhesive layer measured 16 mm wide (measured width of 10 mm) and 16 mm long. Next, the peeling liner was removed from the double-sided sample adhesive tape 10 that was obtained by cutting the double-sided adhesive tape provided in the Production Example 1 into 16 mm wide and 16 mm long. The double-sided sample adhesive tape 10 was stuck to the wall paper 52.

Tensile Test;

The aluminum plate 51 was mounted on the test device, and the double-sided sample adhesive tape 10 was press-adhered onto the wall paper 52 by rolling a 10-kg stainless steel roller one round trip. Next, by nipping the tab, the double-sided sample adhesive tape 10 was pulled at a peeling angle of 2° and a pulling rate of 300 mm/min. to peel it off the wall paper 52. The double-sided sample adhesive tape 10 was measured for its proportional limit, breaking point and breaking elongation to be 0.32 (N/15 mm), 3.36 (N/15 mm) and 840 (%), respectively, as shown in Table 1 below. After the tensile test, the wall paper was observed for its surface but there was recognized no adhesive that was remaining. Namely, in this Example, it was learned that both the first and second adhesive layers were favorably peeled off simultaneously.

Holding Test: After the double-sided sample adhesive tape 10 was stuck to the wall paper 52 via the first adhesive layer (rubber-type adhesive) as described above, a hook 53 made of a styrol resin was attached and was pressed with a static load of 10 kg for 30 seconds. Next, a load W of 3.7 kg was hung from the hook 53. The time (minutes) for holding the hook 53 using the double-sided sample adhesive tape 10 was measured to be > 10,000 minutes as shown in Table 1 appearing below.

Example 5

The method described in Example 1 was repeated. In this Example, however, the first adhesive layer of the first adhesive element was transferred onto the wall paper before sticking the double-sided sample adhesive tape onto the wall paper.

As described in Example 1, the wall paper 52 made of the vinyl chloride resin was stuck to the aluminum plate 51. Thereafter, the first adhesive layer (rubber-type adhesive) was transferred onto a predetermined position of the wall paper 52 from the transfer sheet (sample 4) having the adhesive layer produced in the Production Example 2. The transferred first adhesive layer measured 16 mm wide (measured width of 16 mm) and 16 mm long. Next, the peeling liner was removed from the double-sided sample adhesive tape 10 that was obtained by cutting the double-sided adhesive tape provided in the Production Example 1 into 16 mm wide and 16 mm long. The double-sided sample adhesive tape 10 was stuck to the wall paper 52. The aluminum plate 51 was mounted on the test device, and the double-sided sample adhesive tape 10 was press-adhered onto the wall paper 52 by rolling a 10-kg stainless steel roller one round trip. Next, by nipping the tab, the double-sided sample adhesive tape 10 was pulled at a peeling angle of 2° and a pulling rate of 300 mm/min. to peel it off the wall paper 52. The double-sided sample adhesive tape 10 was measured for its proportional limit, breaking point and breaking elongation to be 18 (N/15 mm), 44

(N/15 mm) and 750 (%), respectively, as shown in Table 1 below. After the tensile test, the wall paper was observed for its surface and it was confirmed that the first and second adhesive layers had not been peeled off, simultaneously.

Holding Test:

After the double-sided sample adhesive tape 10 was stuck to the wall paper 52 via the first adhesive layer (rubber-type adhesive) as described above, a hook 53 made of a styrol resin was attached and was pressed with a static load of 10 kg for 30 seconds. Next, a load W of 3.7 kg was hung from the hook 53. The time (minutes) for holding the hook 53 using the double-sided sample adhesive tape 10 was measured to be > 10,000 minutes as shown in Table 1 appearing below.

Table 1

^• As will be understood from the test results described in Table 1 above, the adhesive tape of the present invention can be strongly adhered to the material and can, further, be easily peeled off the material together with the first and second adhesive layers. From these results, it can be evaluated that the adhesive tape of the present invention is a totally excellent peelable adhesive tape. From these test results, further, it will be learned that the conditions for simultaneously peeling the first and second adhesive layers are such that the first adhesive layer (adhesive layer of the transfer sheet) exhibits a tensile test value (breaking stress: maximum value) which is smaller than that of the second adhesive layer (adhesive layer of the double-sided sample adhesive tape). Example 6

The method described in Example 1 was repeated to test the holding force. In this Example, however, the first adhesive layer of the first adhesive element was transferred onto the wall paper or onto the second adhesive element (double-sided sample adhesive tape) before sticking the double-sided sample adhesive tape onto the wall paper. There were used the following 16 kinds of wall papers.

Wall paper 1 : Vinyl chloride resin, lattice-patterned surface, LY9515 (product number), manufactured by Lilicala Co. Wall paper 2: Vinyl chloride resin, amorphous foamed emboss-patterned surface, LY9519

(product number), manufactured by Lilicala Co.

Wall paper 3: Vinyl chloride resin, amorphous foamed emboss-patterned surface, LY952

(product number), manufactured by Lilicala Co.

Wall paper 4: Vinyl chloride resin, amorphous foamed emboss-patterned surface, LY9540 (product number), manufactured by Lilicala Co.

Wall paper 5: Vinyl chloride resin, amorphous foamed emboss-patterned surface, LY9552

(product number), manufactured by Lilicala Co.

Wall paper 6: Vinyl chloride resin, emboss-patterned surface, SP9903 (product number), manufactured by Sangetsu Co. Wall paper 7: Vinyl chloride resin, emboss-patterned surface, SP9904 (product number), manufactured by Sangetsu Co.

Wall paper 8: Vinyl chloride resin, mesh-patterned surface, SP9912 (product number), manufactured by Sangetsu Co.

Wall paper 9: Vinyl chloride resin, mesh-patterned surface, SP9917 (product number), manufactured by Sangetsu Co.

Wall paper 10: Vinyl chloride resin, amorphous foamed emboss-patterned surface,

SP9918 (product number), manufactured by Sangetsu Co.

Wall paper 11 : Vinyl chloride resin, amorphous foamed emboss-patterned surface,

SP9919 (product number), manufactured by Sangetsu Co. Wall paper 12: Vinyl chloride resin, amorphous foamed emboss-patterned surface,

SP9922 (product number), manufactured by Sangetsu Co. Wall paper 13: Vinyl chloride resin, amorphous foamed emboss-patterned surface, SP9923 (product number), manufactured by Sangetsu Co.

Wall paper 14: Vinyl chloride resin, amorphous foamed emboss-patterned surface, SP9926 (product number), manufactured by Sangetsu Co. Wall paper 15: Vinyl chloride resin, amorphous foamed emboss-patterned surface, SP9932 (product number), manufactured by Sangetsu Co.

Wall paper 16: Vinyl chloride resin, emboss-patterned surface, SP9950 (product number), manufactured by Sangetsu Co.

For testing the holding force, there were used four kinds of weights W weighing 5.06 kg, 4.7 kg, 3.7 kg and 3.0 kg.

Test 1

The wall paper 52 of vinyl chloride resin was stuck to the aluminum plate 51 as described in Example 1. Next, the peeling liner was removed from the double-sided sample adhesive tape 10 obtained by cutting the double-sided adhesive tape provided in the Production Example 1 above into 25 mm wide and 56 mm long. Thereafter, the first adhesive layer (rubber/acrylic blended adhesive) was transferred from the transfer sheet (sample 2) having the adhesive layer produced in the Production Example 2 above onto the second adhesive layer (rubber-type adhesive) which has been exposed of the double- sided sample adhesive tape 10. The area of the first adhesive layer that was transferred was 1,400 mm², i.e., 25 mm wide and 56 mm long. After the first and second adhesive layers were laminated as described above, the double-sided sample adhesive tape 10 was stuck to the predetermined position of the wall paper 52.

After the double-sided sample adhesive tape 10 was stuck to the wall paper 52 via the first adhesive layer (rubber/acrylic blended adhesive) as described above, a hook 53 made of a styrol resin was attached and was pressed with a static load of 10 kg for 30 seconds. Next, the loads W of different weights were hung from the hook 53. The time (minutes) for holding the hook 53 using the double-sided sample adhesive tape 10 was measured for each of the loads W. The holding (minutes) was repetitively measured 7 times and was regarded to be "acceptable" when the average value was > 25,000 minutes, and the load endurance was calculated. As shown in Table 2 below, despite of having the width of 25 mm, not all of the tested adhesive tapes could endure the load of 3.7 kg but two of them could not endure.

Test 2 The wall paper 52 of vinyl chloride resin was stuck to the aluminum plate 51 as described in Example 1. Next, the first adhesive layer (rubber/acrylic blended adhesive) was transferred from the transfer sheet (sample 2) having the adhesive layer produced in the Production Example 2 above onto a predetermined position of the wall paper 52. The transfer sheet was pushed onto the wall paper by using a plastic spatula so as to be transferred thereon. The area of the first adhesive layer that was transferred was 720 mm , i.e., 16 mm wide and 45 mm long. Next, the peeling liner was removed from the double- sided sample adhesive tape 10 that was obtained by cutting the double-sided adhesive tape provided in the Production Example 1 above into 16 mm wide and 45 mm long. Thereafter, the double-sided sample adhesive tape 10 was stuck to the wall paper 52 being overlapped on the first adhesive layer.

After the double-sided sample adhesive tape 10 was stuck to the wall paper 52 via the first adhesive layer (rubber/acrylic blended adhesive) as described above, a hook 53 made of a styrol resin was attached and was pressed with a static load of 10 kg for 30 seconds. Next, the loads W of different weights were hung from the hook 53. The time (minutes) for holding the hook 53 with the double-sided sample adhesive tape 10 was measured for each of the loads W. The holding (minutes) was repetitively measured 7 times and was regarded to be "acceptable" when the average value was > 25,000 minutes, and the load endurance was calculated. As shown in Table 2 below, the tested adhesive tapes all endured the load of 3.7 kg despite of having changed the width of the tape down to 16 mm. Besides, 14 of them could endure the load of 5.06 kg.

Table 2

As will be understood from the test results of Table 2 above, the adhesive tape of the present invention offers very favorable load endurance when the first adhesive layer is stuck to the material and, next, the second adhesive layer (second adhesive element) is laminated on the first adhesive layer, rather than when the first adhesive layer of the first adhesive element is laminated readily on the second adhesive layer of the second adhesive element.

Claims

We Claim:

1. A peelable adhesive tape used being stuck to an adherend, comprising a pair of: a first adhesive element having a first adhesive layer directly applied to the adherend; and a second adhesive element, capable of being stretched, including a second adhesive layer applied to said adherend via said first adhesive layer and a base member that supports said second adhesive layer; wherein said first adhesive layer has the strain and stress smaller than the strain and stress of said second adhesive element as measured by a tensile test.

2. An adhesive tape according to claim 1, wherein said base member further has a third adhesive layer on the side opposite to said second adhesive layer.

3. An adhesive tape according to claim 2, wherein said base member comprises a single-layer or a multi-layer highly stretching polymer material.

4. An adhesive tape according to claim 3, wherein said highly stretching polymer material is at least one kind of polymer film selected from the following groups: (1) a polymer having a breaking elongation of 50 to 1,200% in the lengthwise direction, an elasticity recovery of smaller than 50% after stretched, and a Young's modulus of 6,894.7 to 499,865.8 KPa;

(2) a foamed polymer film;

(3) a polymer film having an yield stress or a proportional critical stress of not larger than 20 N/15 mm, a tensile breaking strength of not smaller than 30 N/15 mm, and a breaking elongation of not smaller than 150%; and

(4) a polymer film containing a thermoplastic rubber and an adhesive-forming resin.

5. An adhesive tape according to claim 1, wherein said base member is a composite member of a foamed polymer film and a non-foamed polymer film.

6. An adhesive tape according to claim 1 , wherein said base member is for temporarily supporting said second adhesive layer, and comprises protection means that can be peeled off at a moment when the second adhesive element is stuck.

7. An adhesive tape according to claim 1 , wherein when said adhesive tape is pulled from the surface of said adherend at an angle of not larger than 35° and is peeled while being stretched, said first and second adhesive layers are peeled off together with said base member.

8. An adhesive tape according to claim 1 , wherein the adhering force of when said adhesive tape is peeled while being stretched from the surface of said adherend is smaller than the breaking stress of when said adhesive tape is subjected to the tensile test.

9. An adhesive tape according to claim 1 , wherein the adhering force of when said adhesive tape is peeled while being stretched from the surface of said adherend is 1/1.5 or smaller of the breaking stress of when said adhesive tape is subjected to the tensile test.

10. An adhesive tape according to claim 1, wherein said second adhesive layer has a thickness of 10 to 1 ,000 μm.

11. An adhesive tape according to claim 1, wherein said first adhesive layer is a rubber adhesive, an acrylic adhesive, or a mixture thereof.

12. An adhesive tape according to claim 1 , wherein said first adhesive layer has a thickness of 25 to 3,000 μm.

13. An article-attaching kit for attaching an article to an adherend via an adhesive layer, and having a peelable adhesive tape according to claim 1 in combination with an article that is attached and fixed to said adherend via the first and second adhesive layers of said adhesive tape, wherein when said article is to be removed, as required, after it has been attached, said adhesive tape and the first and second adhesive layers are removed together with said article from said adherend.

14. An article-attaching kit according to claim 13, wherein after the first adhesive layer of said first adhesive element is applied to said adherend, an article provided with said second adhesive element is attached to said adherend to be adhered via said first adhesive layer.

15. An article-attaching kit according to claim 13, wherein after the first adhesive layer of said first adhesive element is applied to said adherend, said second adhesive element is attached to said adherend via said first adhesive layer, and said article is attached to said adherend via said first and second adhesive layers.