Pressure-sensitive adhesive tape

Abstract

To provide a pressure-sensitive adhesive tape, including first and second pressure-sensitive adhesive layers having mutually different compositions, in which improvement of an adhesion force between the pressure-sensitive adhesive layers is achieved.SOLUTION: A pressure-sensitive adhesive tape 10 includes a first pressure-sensitive adhesive layer 3 and a second pressure-sensitive adhesive layer 5 which is directly laminated on the first pressure-sensitive adhesive layer 3 and has a composition different from that of the first pressure-sensitive adhesive layer 3. At least one of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 5 contains a surface modifier. A laminate 12 includes a pressure-sensitive adhesive tape 10, a first release liner 1 covering the first pressure-sensitive adhesive layer 3, and a second release liner 7 covering the second pressure-sensitive adhesive layer 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to an adhesive tape in which a first adhesive layer and a second adhesive layer are directly laminated together. [Background technology]

[0002] Different properties may be required for the first and second adhesive layers, such as one side of the double-sided tape being required to have strong adhesive strength and the other side being required to be easy to remove. The specification of JP 2020-164741 A (Patent Document 1) describes a double-sided adhesive tape for protecting a screen, which includes a substrate, a first adhesive layer formed on one side of the substrate, and a second adhesive layer formed on the second side of the substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2020-164741 Summary of the Invention [Problem to be solved by the invention]

[0004] In the double-sided adhesive tape described in Patent Document 1, by providing a silicone-based adhesive layer as the first adhesive layer, it is possible to improve wettability with respect to the adherend, and by providing an acrylic-based adhesive layer or the like as the second adhesive layer, it is possible to strongly bond the tape to the substrate. Here, in order to bond two adherends together, it is sufficient to have two adhesive surfaces, and a substrate is not necessarily required.

[0005] However, when a substrate is not used and different properties are required for the two adhesive surfaces, the first adhesive layer and the second adhesive layer must be directly laminated. However, when the first adhesive layer and the second adhesive layer having different properties are laminated, the adhesion between the two adhesive layers is likely to be insufficient. If the adhesion between the adhesive layers is insufficient, problems such as peeling between the adhesive layers when peeling off the release liner of the other adhesive surface after attaching one adhesive surface to the first adherend, or peeling easily occurring at the interface between the two adhesive layers after fixing the two adherends to each other may occur.

[0006] In view of the above problems, an object of the present invention is to provide an adhesive tape comprising a first adhesive layer and a second adhesive layer laminated together, in which the interlayer adhesion between the two adhesive layers is improved. [Means for solving the problem]

[0007] An example of the adhesive tape disclosed in the present specification includes a first adhesive layer and a second adhesive layer that is directly laminated on the first adhesive layer and has a different composition from the first adhesive layer, and at least one of the first adhesive layer and the second adhesive layer contains a surface modifier. Effect of the Invention

[0008] According to the adhesive tape disclosed in the present specification, at least one of the first and second adhesive layers which are directly laminated together contains a surface modifier, thereby improving the interlayer adhesion between the first and second adhesive layers. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view illustrating an example of a pressure-sensitive adhesive tape according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view showing a configuration of a modified pressure-sensitive adhesive tape according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] FIG. 1 is a cross-sectional view showing an adhesive tape 10 and a laminate 12 having the adhesive tape 10, which is one example of the embodiment disclosed in this specification.

[0011] The pressure-sensitive adhesive tape 10 according to this embodiment is a double-sided pressure-sensitive adhesive tape having no substrate, and includes a first pressure-sensitive adhesive layer 3, and a second pressure-sensitive adhesive layer 5 that is laminated directly on the first pressure-sensitive adhesive layer 3 and has a different composition from the first pressure-sensitive adhesive layer 3. At least one of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 5 contains a surface modifier. The laminate 12 includes the pressure-sensitive adhesive tape 10, a first release liner 1 covering the first pressure-sensitive adhesive layer 3, and a second release liner 7 covering the second pressure-sensitive adhesive layer 5.

[0012] The surface modifier is not particularly limited as long as it is a substance that can change the surface state of the adhesive layer and improve the adhesion between the first adhesive layer and the second adhesive layer. For example, a surface modifier containing a silicone component and an acrylic component in the molecule can be used as the surface modifier. Examples of the silicone component include compounds having a dimethylsiloxane group or a cyclosiloxane group. A known acrylic polymer can be used as the acrylic component.

[0013] As a commercially available surface modifier, for example, KP-410, KP-411, KP-412, KP-413, KP-414, KP-415, KP-416, KP-418, KP-420, KP-422, and KP-423 manufactured by Shin-Etsu Silicone Co., Ltd. may be used. Among these, surface modifiers containing a double-ended acrylic modified polysiloxane having (meth)acryloyl groups added to both ends (KP-410, KP-411, KP-412, KP-413, KP-414, KP-415, and KP-423) are preferably used to improve the adhesion between the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 5. The surface modifier contained in the first pressure-sensitive adhesive layer 3 and the surface modifier contained in the second pressure-sensitive adhesive layer 5 may be the same as or different from each other.

[0014] <Configuration of Adhesive Layer> The first adhesive layer 3 and the second adhesive layer 5 may be layers formed mainly of adhesives having different compositions, and when one is an acrylic adhesive layer, a urethane adhesive layer, a silicone adhesive layer, a rubber adhesive layer, a polyester adhesive layer, or an acrylic-urethane adhesive layer, the other may be an adhesive layer of another type. For example, if the first adhesive layer 3 is an acrylic adhesive layer, it is easy to design it so that it has a strong adhesive force to the adherend, and if the second adhesive layer 5 is a silicone adhesive layer, it is possible to improve the wettability to the optical members of the display.

[0015] Alternatively, the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 5 may both be acrylic pressure-sensitive adhesive layers having different compositions.

[0016] In the pressure-sensitive adhesive tape 10 of the present embodiment, at least one of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 5 contains a surface modifier, thereby improving the adhesion between the two pressure-sensitive adhesive layers compared to a case in which neither the first pressure-sensitive adhesive layer 3 nor the second pressure-sensitive adhesive layer 5 contains a surface modifier. A surface modifier changes the surface state of a resin film by segregating on the surface of the resin film or the like, but the effect of improving the interlayer adhesion between pressure-sensitive adhesive layers is a phenomenon discovered independently by the present inventors.

[0017] When the first adhesive layer 3 is formed from a cured product of an acrylic adhesive and the second adhesive layer 5 is formed from a cured product of a silicone-based adhesive, the concentration of the surface modifier in the first adhesive layer 3 may be higher than the concentration of the surface modifier in the second adhesive layer 5.

[0018] In both the acrylic pressure-sensitive adhesive layer and the silicone pressure-sensitive adhesive layer, when the concentration of the surface modifier is low, the interlayer adhesion between the pressure-sensitive adhesive layers increases as the concentration of the surface modifier increases, but increasing the concentration of the surface modifier in the acrylic pressure-sensitive adhesive layer is more effective in increasing the interlayer adhesion than increasing the concentration of the surface modifier in the silicone pressure-sensitive adhesive layer. On the other hand, if the concentration of the surface modifier is too high, the cohesive force of the silicone pressure-sensitive adhesive and the acrylic pressure-sensitive adhesive layer decreases, and the possibility of contaminating the adherend increases.

[0019] The concentration of the surface modifier in the first pressure-sensitive adhesive layer 3 may be, for example, about 0.2% by mass or more and 10.0% by mass or less, and the concentration of the surface modifier in the second pressure-sensitive adhesive layer 5 may be, for example, about 0.1% by mass or more and 5.0% by mass or less. In order to sufficiently increase the interlayer adhesion between the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 5 and to keep contamination of the adherend relatively small, the concentration of the surface modifier in the first pressure-sensitive adhesive layer 3 may be, for example, about 1.0% by mass or more and 3.5% by mass or less, and the concentration of the surface modifier in the second pressure-sensitive adhesive layer 5 may be, for example, about 0.5% by mass or more and 3.0% by mass or less.

[0020] When the first adhesive layer 3 is an acrylic adhesive layer, a urethane adhesive layer, or an acrylic-urethane adhesive layer, the first adhesive layer 3 may contain at least one of an isocyanate curing agent, an epoxy curing agent, and a metal chelate curing agent at an appropriate concentration, and may be formed by thermal curing. However, if the first adhesive layer 3 does not contain an isocyanate curing agent, but contains at least one of an epoxy curing agent and a metal chelate curing agent, the interlayer adhesion between the adhesive layers can be increased more effectively than when the first adhesive layer 3 contains an isocyanate curing agent. When only a metal chelate curing agent is used as the curing agent of the first adhesive layer 3, the interlayer adhesion between the adhesive layers can be increased more effectively.

[0021] The concentration of the metal chelate curing agent component contained in the first adhesive layer 3 may be a concentration that allows the first adhesive layer 3 to be cured with sufficient cohesive force, and may be, for example, about 0.005% by mass to 2.0% by mass. If the amount of curing agent added is too small, the adhesive will not be cured sufficiently, and if the amount of curing agent added is too large, the adhesive layer will become hard and will not be able to exert sufficient adhesive force to the adherend. If the concentration of the metal chelate curing agent component in the first adhesive layer 3 is 0.05% by mass to 1.0% by mass, the interlayer adhesion between the first adhesive layer 3 and the second adhesive layer 5 can be effectively increased when a surface modifier is added to at least one of the first adhesive layer 3 and the second adhesive layer 5. If the concentration of the metal chelate curing agent component in the first adhesive layer 3 is 0.08% by mass to 0.5% by mass, the adhesive will not be significantly reduced and will be able to exert sufficient holding power.

[0022] The silicone adhesive used to form the second adhesive layer 5 may be a known adhesive of the type cured by peroxide, a known adhesive of the addition curing type, or the like. When using an addition curing type silicone adhesive, it may be cured using a catalyst containing a platinum complex, or a known curing agent as necessary. Commercially available silicone adhesives include KR-3704 and X40-3306 manufactured by Shin-Etsu Chemical Co., Ltd., DC7651ADHESIVE and SD7587L PSA manufactured by Toray Dow Corning, and SE9500 and SE9600 manufactured by Aica Corporation.

[0023] The interlayer adhesion between the first adhesive layer 3 and the second adhesive layer 5 varies depending on the combination of adhesives used, but may be, for example, 0.30 N / 25 mm or more, preferably 1.0 N / 25 mm or more, and more preferably 2.0 N / 25 mm or more.

[0024] The first adhesive layer 3 containing the above-mentioned curing agent is a heat-curable type, but the first adhesive layer 3 may also contain a photoinitiator and be formed from an acrylic adhesive composition cured by ultraviolet light or the like.

[0025] The first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 5 may also contain a biomass material derived from an organism. For example, by containing a rosin-based tackifier or a terpene-based tackifier in an amount of 10 parts by mass or more per 100 parts by mass of the dry weight of the pressure-sensitive adhesive, a pressure-sensitive adhesive layer that addresses environmental issues can be formed.

[0026] The thickness of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer may be arbitrary, and may be, for example, about 2 μm to 100 μm, or 5 μm to 50 μm, for both the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 5. If the thickness of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer is too thin, it becomes difficult to apply the layer to the set thickness, and the adhesive strength between the pressure-sensitive adhesive layers is likely to decrease, whereas if the thickness of the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer is too thick, the manufacturing cost increases.

[0027] The adhesive strength of the first adhesive layer 3 to the SUS BA plate is preferably, for example, 0.1 N / 25 mm or more under the conditions of 23° C., relative humidity 50%, peel angle 180°, and peel speed 300 mm / min. The adhesive strength of the second adhesive layer 5 to the SUS BA plate is preferably, for example, 0.03 N / 25 mm or more.

[0028] By making the adhesion strength between the first adhesive layer 3 and the second adhesive layer 5 greater than the adhesion strength of the second adhesive layer 5 to the adherend, it is possible to make it difficult for interlayer peeling to occur between the first adhesive layer 3 and the second adhesive layer 5 when the first adhesive layer 3 of the adhesive tape 10 of this embodiment is adhered to the first adherend, the second adherend is adhered to the second adhesive layer 5, and then the second adherend is peeled off from the second adhesive layer 5. <Release liner> In the laminate 12, the first release liner 1 and the second release liner 7 may have a paper substrate, a filling layer formed on at least one surface of the substrate, and a release agent layer formed on the surface of the filling layer. As the substrate, fine paper, kraft paper, glassine paper, etc. can be used.

[0029] The first release liner 1 and the second release liner 7 may have a resin substrate and a release agent layer provided on the substrate. In this case, the substrate may be made of polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), or the like.

[0030] The first peel force required to peel the first release liner 1 from the first adhesive layer 3 and the second peel force required to peel the second release liner 7 from the second adhesive layer 5 may be the same as or different from each other. By making the first peel force smaller than the second peel force, it becomes easier to peel the first release liner 1 from the first adhesive layer 3 side.

[0031] <Examples of how to use the laminate> When the first pressure-sensitive adhesive layer 3 is formed, for example, from a cured product of an acrylic pressure-sensitive adhesive and the second pressure-sensitive adhesive layer 5 is formed from a cured product of a silicone pressure-sensitive adhesive, and the adhesive strength of the first pressure-sensitive adhesive layer 3 to the first adherend is stronger than the adhesive strength of the second pressure-sensitive adhesive layer 5 to the second adherend, the peel force when peeling off the second release liner 7 can be designed to be stronger than the peel force when peeling off the first release liner 1. Furthermore, in the laminate 12 of this embodiment, the interlayer adhesion between the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 5 can be made stronger than the adhesive strength of the second pressure-sensitive adhesive layer 5 to the second adherend and the peel force when peeling off the second release liner 7.

[0032] When using the laminate 12 designed in this manner, first, the first release liner 1 is peeled off and the first adhesive layer 3 is attached to the first adherend. Next, the second release liner 7 is peeled off and the second adhesive layer 5 is attached to the second adherend, thereby fixing the second adherend to the first adherend via the adhesive tape 10. According to the laminate 12 and adhesive tape 10 of this embodiment, when the second adhesive layer 5 is peeled off from the second adherend, it is possible to peel it off from the second adherend without peeling at the interface between the first adhesive layer 3 and the second adhesive layer 5.

[0033] The adhesive tape 10 of this embodiment can be used for a variety of purposes, but can also be used, for example, when attaching a screen protection member made of an optical film or optical glass to a screen display member of a portable device or the like, with the screen display member being the second adherend and the screen protection member being the first adherend.

[0034] The configurations of the pressure-sensitive adhesive tape 10 and the laminate 12 described above can be appropriately modified without departing from the spirit of the present invention. For example, as in the pressure-sensitive adhesive tape 20 according to a modified example shown in FIG. 2, the laminate 12 may have a configuration in which the second release liner 7 is replaced with a surface substrate 14 made of a transparent resin such as PET. In this case, the laminate 16 has a configuration including the pressure-sensitive adhesive tape 20 and the first release liner 1 covering the first pressure-sensitive adhesive layer 3. A primer layer for improving adhesion may be provided on the second pressure-sensitive adhesive layer 5 side of the surface substrate 14. In addition, in the laminate 16, the positions at which the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 5 are formed may be interchanged.

[0035] In addition, in the pressure-sensitive adhesive tape 10 shown in FIG. 1, another pressure-sensitive adhesive layer may be laminated. For example, a third pressure-sensitive adhesive layer having the same composition as the first pressure-sensitive adhesive layer 3 except that it does not contain a surface modifier may be provided on the surface of the first pressure-sensitive adhesive layer 3 opposite to the second pressure-sensitive adhesive layer 5, and a fourth pressure-sensitive adhesive layer having the same composition as the second pressure-sensitive adhesive layer 5 except that it does not contain a surface modifier may be provided on the surface of the second pressure-sensitive adhesive layer 5 opposite to the first pressure-sensitive adhesive layer 3. In such a pressure-sensitive adhesive tape, the adhesion between the first pressure-sensitive adhesive layer 3 and the third pressure-sensitive adhesive layer, and the adhesion between the second pressure-sensitive adhesive layer 5 and the fourth pressure-sensitive adhesive layer are improved, and since the pressure-sensitive adhesive layer that comes into contact with the adherend does not contain a surface modifier, contamination of the adherend can be reduced. EXAMPLES

[0036] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0037] -Preparation of adhesive tape- A coating liquid was prepared by adding a predetermined amount of additives and, if necessary, a predetermined amount of surface modifier A ("KP-423" manufactured by Shin-Etsu Chemical Co., Ltd.) to a commercially available silicone-based adhesive. This coating liquid was applied to one side of a PET substrate ("Cosmoshine A4360" manufactured by Toyobo Co., Ltd. ("Cosmoshine" is a registered trademark)) or a second release liner made of PET having a fluorine-based release agent layer ("FSC6" manufactured by Nippa Corporation) using a comma-type coater so that the thickness after drying was 25 μm, and the coating was dried by heating to form a second adhesive layer. The above PET substrate had an easy-adhesion layer on one side. Thereafter, a commercially available release liner was temporarily attached to the exposed surface of the second adhesive layer.

[0038] Next, a coating liquid was prepared by adding a predetermined amount of curing agent and, if necessary, a predetermined amount of surface modifier A to a commercially available acrylic adhesive. Almost all (about 100% by mass) of surface modifier A was a surface modifier component. This coating liquid was applied to the release surface of a commercially available release liner A ("E7002" manufactured by Toyobo) having a PET substrate and a silicone release agent layer using a comma coater so that the thickness after drying was 25 μm, and the first adhesive layer was formed by heating and drying.

[0039] Next, the first adhesive layer formed on the first release liner and the second adhesive layer formed on the surface substrate or the second release liner were bonded together to produce a laminate equipped with an adhesive tape. The produced laminate was aged in an environment of 40°C for about 72 hours.

[0040] Tables 1 to 5 show the configurations of the laminates produced as Examples 1 to 35 and the compositions of each adhesive layer, and Table 6 shows the configurations of the laminates produced as Comparative Examples 1 to 5 and the compositions of each adhesive layer. The number of parts of the surface modifier and the curing agent added in the first adhesive layer shown in Tables 1 to 6 represents the number of parts of the surface modifier and the curing agent products added when the acrylic adhesive containing an organic solvent is taken as 100 parts by mass. The number of parts of the surface modifier and the additives added in the second adhesive layer represents the number of parts of the surface modifier and the additive products added when the silicone adhesive containing an organic solvent is taken as 100 parts by mass. The concentration of the surface modifier (unit: wt%) shown in Tables 1 to 6 indicates the concentration of the surface modifier in the entire first adhesive layer or the second adhesive layer.

[0041] [Table 1]

[0042] [Table 2]

[0043] [Table 3]

[0044] [Table 4]

[0045] [Table 5]

[0046] [Table 6] In Examples 1 to 35 and Comparative Examples 1 to 5, a commercially available silicone-based adhesive B was used to form the second adhesive layer. In Examples 1 to 3 and Comparative Example 1, a commercially available acrylic adhesive A and a commercially available isocyanate-based curing agent A were used to form the first adhesive layer. The acrylic adhesive A is a so-called strong adhesive type adhesive, and has an acrylic copolymer containing a unit derived from butyl acrylate. Approximately 11.8% of the dry weight of the acrylic adhesive A was a plant-derived component. The acrylic adhesive A contained approximately 45.0% by mass of resin solids, and the isocyanate-based curing agent A contained approximately 35.0% by mass of a curing agent component.

[0047] In Examples 4 to 6 and Comparative Example 2, a commercially available acrylic adhesive C was used for forming the first adhesive layer. The acrylic adhesive C was a one-liquid type strong adhesive, and contained approximately 33.0% by mass of resin solid content.

[0048] In Examples 7 to 35 and Comparative Examples 3 to 5, a commercially available acrylic adhesive D was used to form the first adhesive layer. The acrylic adhesive D is a strong adhesive type adhesive, and has an acrylic copolymer containing a unit derived from 2-ethylhexyl acrylate. In these Examples or Comparative Examples, as shown in Tables 1 to 6, an isocyanate-based curing agent B, an epoxy-based curing agent C, or a metal chelate-based curing agent D was used to form the first adhesive layer. The acrylic adhesive D contained about 50.0% by mass of resin solids, the isocyanate-based curing agent B contained about 45% by mass of a curing agent component, and the epoxy-based curing agent C and the metal chelate-based curing agent D contained about 5% by mass of a curing agent component, respectively. In the laminate produced in Example 29, the curing agent concentration in the first adhesive layer was 0.03% by mass, and in the laminate produced in Example 34, the curing agent concentration in the first adhesive layer was 0.15% by mass.

[0049] In Examples 1 to 34 and Comparative Examples 1 to 5, in order to measure the interlayer adhesion between the first and second pressure-sensitive adhesive layers, a laminate was prepared in which a PET substrate (surface substrate), a second pressure-sensitive adhesive layer, a first pressure-sensitive adhesive layer, and a release liner A were provided in this order, as shown in Fig. 2. In Example 35, a laminate was prepared in which a release liner B, a second pressure-sensitive adhesive layer, a first pressure-sensitive adhesive layer, and a release liner A were provided in this order, as shown in Fig. 1.

[0050] -Measurement of adhesive strength of adhesive tape to SUS- The laminates prepared in Examples 1 to 34 and Comparative Examples 1 to 5 were cut into strips of 25 mm wide and 150 mm long to prepare test pieces, and then the first release liner was peeled off, and the exposed first adhesive layer was attached to a SUS BA plate to measure the adhesive strength. Specifically, the test pieces of the laminates cut to a width of 25 mm were attached to the adherend, the SUS BA plate, and pressed with a 2 kg roller twice, and left to stand at 23°C and a relative humidity of 50% for 24 hours. The force required to peel these test pieces from the SUS BA plate was measured using a universal material testing machine (TENSILON RT1-1225, manufactured by A&D Co., Ltd.) at a peel speed of 300 mm / min, and this was taken as the adhesive strength (N / 25 mm). The peel angle was 180 degrees. When interlayer peeling occurs between the first adhesive layer and the second adhesive layer, the measured value of this test is the interlayer adhesion strength between the first adhesive layer and the second adhesive layer.

[0051] For the laminate produced in Example 35, the adhesive strength of the second adhesive layer to the SUS BA plate was measured as follows. That is, after cutting into a strip of 25 mm width and 150 mm length to prepare a test piece, the first release liner was peeled off and the exposed first adhesive layer side was attached to a PET film having a thickness of 25 μm. Next, the second release liner was peeled off and the test piece was attached to the SUS BA plate from the exposed second adhesive layer side. The force required to peel the test piece from the SUS BA plate after 1 minute and after 24 hours at 23° C. and 50% relative humidity was measured using a universal material testing machine at a peel speed of 300 mm / min, and this was taken as the adhesive strength (N / 25 mm).

[0052] -Measurement of retention and retention duration- A test piece measuring 25 mm wide and 100 mm long was cut out from each of the laminates produced in Examples 29 to 34, and a 25 mm×25 mm portion at one end of the test piece was attached to a SUS steel plate from the first adhesive layer side. The portion attached to the SUS steel plate was strongly and uniformly pressed using a squeegee.

[0053] Next, the SUS steel plate was placed vertically so that the bonded portion of the test piece was at the top, and a 1 kg weight was hung from the other end of the test piece that was at the bottom. In this state, the time until the laminate (adhesive tape) was completely peeled off was measured as the holding strength duration. If the test piece had not fallen off after 50,000 seconds had elapsed since the start of the measurement, the amount of displacement of the test piece at that point (unit: mm) was measured as a value representing the holding strength. The measurement was performed at 40°C.

[0054] -Measurement results- Table 7 shows the results of the adhesive strength measurement test of the laminates produced in Examples 1 to 3 and Comparative Example 1.

[0055] [Table 7] As shown in Table 7, in all the measured test pieces, interlayer peeling was observed between the first adhesive layer and the second adhesive layer. From this, it was confirmed that the interlayer adhesion between the first adhesive layer and the second adhesive layer was weaker than the adhesion of the first adhesive layer to the SUS BA plate. In addition, from a comparison between the laminates produced in Examples 1 to 3 and the laminate produced in Comparative Example 1, it was confirmed that the adhesion between the adhesive layers can be improved by adding a surface modifier to at least one of the first adhesive layer and the second adhesive layer compared to the case where no surface modifier is used.

[0056] Table 8 shows the results of the adhesive strength measurement test of the laminates produced in Examples 4 to 6 and Comparative Example 2.

[0057] [Table 8] From the results shown in Table 8, it was confirmed that even when using a one-component acrylic adhesive B that does not require the addition of a separate curing agent, the adhesion between the adhesive layers can be improved by adding a surface modifier to at least one of the first adhesive layer and the second adhesive layer.

[0058] Table 9 shows the results of the adhesive strength measurement test of the laminates produced in Examples 7 to 14 and Comparative Examples 3 to 5.

[0059] [Table 9] From the results shown in Table 9, it was confirmed that when the same acrylic adhesive D was used to form the first adhesive layer, hardening of the surface modifier was observed regardless of the type of curing agent used, but the effect of improving the adhesion between the adhesive layers was highest when a metal chelate curing agent was used, followed by an epoxy curing agent, and lowest when an isocyanate curing agent was used.

[0060] Table 10 shows the results of the adhesive strength measurement test of the laminates produced in Examples 12 to 28 and Comparative Example 5.

[0061] [Table 10] From the measurement results of the laminates prepared in Examples 17, 19, 21, 23 and 27, and the laminates prepared in Examples 15, 18, 20, 22, 24 and 28, it was found that the interlayer adhesion between the adhesive layers is greatly improved as the concentration of the surface modifier A in the first adhesive layer is increased from 1% by mass to 3.5% by mass. From the measurement results of the laminates prepared in Examples 15 and 16, Examples 17 and 18, and Examples 23 to 26, it was also found that even when the surface modifier A is added to the second adhesive layer formed using a silicone-based adhesive, the interlayer adhesion of the adhesive layers is improved as the addition concentration increases. However, the effect of the amount of the surface modifier added on the interlayer adhesion of the adhesive layers tends to be greater in the first adhesive layer than in the second adhesive layer.

[0062] Table 11 shows the results of the adhesive strength measurement test and the holding strength measurement test for the laminates produced in Examples 29-34.

[0063] [Table 11] From the results shown in Table 11, it was found that the interlayer adhesion between the adhesive layers tends to decrease as the amount of metal chelate curing agent added increases, while the holding power improves as the amount of metal chelate curing agent added increases. When the amount of metal chelate curing agent added to the first adhesive layer is 1.5 parts by mass or more per 100 parts by mass of acrylic adhesive D, the holding power duration is significantly extended during holding power measurement, and the cohesive failure of the first adhesive layer changes to interlayer peeling between the adhesive layers, confirming that the cohesive power is improved.

[0064] Table 12 shows the results of the adhesive strength measurement test for the second adhesive layer of the laminate produced in Example 35.

[0065] [Table 12] As shown in Table 12, in the laminate produced in Example 35, the adhesive strength of the second adhesive layer to the SUS BA plate was about 0.10 N / 25 mm even after 24 hours, which was weaker than the interlayer adhesion strength between the first adhesive layer and the second adhesive layer. Therefore, it was confirmed that the second adhesive layer could be peeled off from the adherend without causing peeling between the adhesive layers. [Industrial Applicability]

[0066] The pressure-sensitive adhesive tape and laminate disclosed in this specification can be used in applications such as bonding different members together, such as bonding a screen protection member for a display device. [Explanation of symbols]

[0067] 1 First release liner 3 First adhesive layer 5 Second adhesive layer 7 Second Release Liner 10, 20 Adhesive tape 12, 16 Laminate 14 Surface base material

Claims

1. A first pressure-sensitive adhesive layer; a second pressure-sensitive adhesive layer that is directly laminated on the first pressure-sensitive adhesive layer and has a composition different from that of the first pressure-sensitive adhesive layer; At least one of the first adhesive layer and the second adhesive layer contains a surface modifier.

2. The adhesive tape according to claim 1 , wherein both the first adhesive layer and the second adhesive layer contain the surface modifier.

3. The pressure-sensitive adhesive tape according to claim 1 , wherein the first pressure-sensitive adhesive layer is formed from a cured product of an acrylic pressure-sensitive adhesive.

4. The pressure-sensitive adhesive tape according to claim 3 , wherein the first pressure-sensitive adhesive layer does not contain an isocyanate-based curing agent, and contains at least one of an epoxy-based curing agent and a metal chelate-based curing agent.

5. The pressure-sensitive adhesive tape according to claim 4 , wherein the first pressure-sensitive adhesive layer contains the metal chelate curing agent at a concentration of 0.005% by mass or more and 2.0% by mass or less.

6. a surface modifier contained in the first pressure-sensitive adhesive layer and a surface modifier contained in the second pressure-sensitive adhesive layer are the same substance; The pressure-sensitive adhesive tape according to claim 2 , wherein a concentration of the surface modifier in the first pressure-sensitive adhesive layer is higher than a concentration of the surface modifier in the second pressure-sensitive adhesive layer.

7. The concentration of the surface modifier in the first pressure-sensitive adhesive layer is 0.2% by mass or more and 10.0% by mass or less, The pressure-sensitive adhesive tape according to claim 2 , wherein a concentration of the surface modifier in the second pressure-sensitive adhesive layer is from 0.1% by mass to 5.0% by mass.

8. The pressure-sensitive adhesive tape according to claim 1 , wherein the surface modifier comprises an acrylic-modified polysiloxane having (meth)acryloyl groups added to both ends of the polysiloxane.

9. The pressure-sensitive adhesive tape according to claim 1 , wherein the second pressure-sensitive adhesive layer is formed from a cured product of a silicone-based pressure-sensitive adhesive.

10. The pressure-sensitive adhesive tape according to claim 1 , wherein an interlayer adhesion between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 0.30 N / 25 mm or more.

11. The pressure-sensitive adhesive tape according to any one of claims 1 to 10, which is a double-sided pressure-sensitive adhesive tape having no substrate.

Images