PRESSURE-SENSITIVE ADHESIVE TAPE

Abstract

The pressure-sensitive adhesive tape of the present invention is a pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer comprising a photo-cured acrylic resin, a metal having a lower potential than that of iron, and an electroconductive material, wherein the pressure-sensitive adhesive layer has a total light transmittance X, per micrometer of the thickness, of 99.85% or less, and the pressure-sensitive adhesive layer has a total light transmittance Y of 6% or more. The present invention can provide a pressure-sensitive adhesive tape having a great adhesive force on both the front side and the back side and having good sacrificial corrosion resistance.

Claims

1. A pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer comprising a photo-cured acrylic resin, a metal having a lower potential than that of iron, and an electroconductive material other than the metal, the pressure-sensitive adhesive layer having a total light transmittance X, per micrometer of a thickness thereof, of 99.85% or less, and the pressure-sensitive adhesive layer having a total light transmittance Y of 6% or more.

2. The pressure-sensitive adhesive tape according to claim 1, wherein the metal having a lower potential than that of iron is zinc.

3. The pressure-sensitive adhesive tape according to claim 1, wherein the electroconductive material is a needle-shaped carbon material.

4. The pressure-sensitive adhesive tape according to claim 3, wherein the needle-shaped carbon material is carbon nanotube.

5. The pressure-sensitive adhesive tape according to claim 1, wherein the photo-cured acrylic resin is a polymerized product of a polymerizable monomer comprising an alkyl(meth)acrylate monomer (A).

6. The pressure-sensitive adhesive tape according to claim 5, wherein the polymerizable monomer further comprises a polar group-containing vinyl monomer (B).

7. A pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer comprising a metal having a lower potential than that of iron, and carbon nanotube.

8. The pressure-sensitive adhesive tape according to claim 7, wherein the pressure-sensitive adhesive layer has a total light transmittance X, per micrometer of a thickness thereof, of 99.85% or less.

9. The pressure-sensitive adhesive tape according to claim 7, wherein the metal having a lower potential than that of iron is zinc.

10. The pressure-sensitive adhesive tape according to claim 7, wherein the pressure-sensitive adhesive layer is made with an acrylic adhesive.

11. The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer has a potential of −700 mV or less in a sacrificial protection test.

12. The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 100 to 3000 μm.

13. The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive tape consists of the pressure-sensitive adhesive layer.

14. The pressure-sensitive adhesive tape according to claim 1, comprising a support, wherein the pressure-sensitive adhesive layer is provided on one side or each of both sides of the support.

15. The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive tape is for use in anticorrosion.

Description

EXAMPLES

[0161] The present invention will now be described in more detail by way of examples, but the present invention is not limited to these examples.

[Pressure-Sensitive Adhesive Tape According to First Invention]

[0162] The pressure-sensitive adhesive tape according to the first invention will be described below by way of examples.

[Total Light Transmittance]

[0163] The total light transmittance of the pressure-sensitive adhesive layer prepared in each of Examples and Comparative Examples was measured in the following manner.

[0164] The total light transmittance Y of the pressure-sensitive adhesive layer was measured in accordance with JIS K7361-1. Specifically, the total light transmittance Y was measured in an atmosphere at 23° C. and a humidity of 50% with a haze mater (e.g., Haze Meter NDH4000 manufactured by NIPPON DENSHOKU INDUSTRIES Co., Ltd.).

[0165] The total light transmittance X (%) per micrometer of the thickness was calculated using the following expression from the total light transmittance Y (%) and the thickness T (μm) of the pressure-sensitive adhesive layer.

[00003]$\begin{array}{cc}\underset{\left(\%\right)}{\mathrm{Total}\mathrm{light}\mathrm{transmittance}}Y=100\times {\left(\frac{\mathrm{Total}\mathrm{light}\mathrm{transmittance}X}{100}\right)}^T& \left[\mathrm{Expression}3\right]\end{array}$

[Sacrificial Protection Test]

[0166] The sacrificial protection test was carried out by the following (1) and (2).

(1) A pressure-sensitive adhesive layer with a size of 150 mm×70 mm was attached to a steel plate SS400 (manufactured by TP Giken Corporation, 150 mm×70 mm) as an adherend.
(2) Thereafter, part (2 mm×2 mm) of the pressure-sensitive adhesive layer was cut out, and a NaCl aqueous solution having a concentration of 3 mass % was dropped thereon. A silver/silver chloride electrode was placed such that the tip of the electrode contacts with the NaCl aqueous solution, and the potential was measured using the electrode.

[0167] In the measurement of the potential, a digital multimeter “CDM-11D” (manufactured by CUSTOM corporation) was used as a tester, and the negative electrode thereof was connected with an electrode “HS-205C” (manufactured DKK-TOA CORPORATION) via an electrode clip and used.

[0168] The sacrificial corrosion resistance was evaluated according to the following criteria on the basis of the result obtained by the above sacrificial protection test. “Good” means that the potential is low and that the sacrificial corrosion resistance is thus excellent, and “Poor” means that the potential is high and that the sacrificial corrosion resistance is thus poor.

(Evaluation)

[0169] Good: Potential is −700 mV or less

[0170] Poor: Potential is more than −700 mV

[Adhesive Force Loss]

[0171] For the pressure-sensitive adhesive layer (pressure-sensitive adhesive double sided tape) prepared in each of Examples and Comparative Examples, the adhesive force on the side irradiated with ultraviolet rays (the adhesive force on the irradiated side) and the adhesive force on the other side of the side irradiated with ultraviolet rays (the adhesive force on the other side) were measured in the following manner.

[0172] The pressure-sensitive adhesive layer obtained in each example was cut into a size of 25 mm×100 mm, which was adhered to a SUS plate to obtain a measurement sample. The measurement sample was fixed to the chucks of a tensile tester (“TENSILON Universal Material Testing Instrument, manufactured by A&D Company, Limited). Then, the pressure-sensitive adhesive layer was pulled over 60 mm or more at a peeling angle of 180° and a rate of 300 mm/min, and an average value of loads (N) detected over that interval by the load cell was recorded, which was used as the adhesive force.

[0173] The above test was carried out on both sides of the pressure-sensitive adhesive layer to obtain the value of the adhesive force on the irradiated side and that on the other side. The adhesive force loss was determined using the expression below, which was evaluated according to the following criteria. “Good” means that the adhesive force loss is small and that the adhesive force of the pressure-sensitive adhesive layer is thus large. “Poor” means that the adhesive force loss is large and that the adhesive force of the pressure-sensitive adhesive layer is thus small.

Adhesive force loss (%)=100×(adhesive force of irradiated side-adhesive force of other side)/(adhesive force of irradiated side)

(Evaluation)

[0174] Good: Adhesive force loss is 40% or less

[0175] Fair: Adhesive force loss is more than 40% and 50% or less

[0176] Poor: Adhesive force loss is more than 50%

[Total Evaluation]

[0177] Good: “Poor” was given in neither the evaluation in the sacrificial protection test nor that in the adhesive force loss.

[0178] Poor: “Poor” was given in at least one of the evaluation in the sacrificial protection test and that in the adhesive force loss.

Example 1

[0179] A pressure-sensitive adhesive composition was prepared according to the formulation described in Table 1. Purge with nitrogen gas was carried on the pressure-sensitive adhesive composition to remove dissolved oxygen. Then, a spacer having a thickness of 600 μm was placed on the release-treated side of a release sheet, and the pressure-sensitive adhesive composition was applied to the release-treated side of the release sheet. Then, the applied pressure-sensitive adhesive composition was covered with another release sheet such that the release-treated side thereof was brought into contact with the pressure-sensitive adhesive composition. The release sheets used were each a PET film (thickness 50 μm) that had undergone mold-release treatment with silicone.

[0180] In that state, the lamp intensity of the chemical lamp was adjusted such that the intensity of irradiation with ultraviolet rays was 5 mW/cm.sup.2 on the release sheet on the cover side, and one side was irradiated with ultraviolet rays for 15 minutes to obtain an anticorrosive pressure-sensitive adhesive double sided tape consisting of a pressure-sensitive adhesive layer alone with release sheets attached to both sides thereof. The thickness of the pressure-sensitive adhesive layer (that is, the pressure-sensitive adhesive double sided tape) was 600 μm. The results are shown in Table 1.

Examples 2 to 6, Comparative Examples 1 to 3

[0181] An anticorrosive pressure-sensitive adhesive double sided tape was obtained in the same manner as in Example 1, except for preparing a pressure-sensitive adhesive composition according to the formulation described in Table 1. The results are shown in Table 1.

TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 4 5 6 1 2 3 Pressure- 2-Ethylhexyl acrylate 85 85 85 85 85 85 85 85 85 sensitive n-Butyl acrylate 15 15 15 15 15 15 15 15 15 adhesive Acrylic acid 5 5 5 5 5 5 5 5 5 composition Olefin polymer 10 10 10 10 10 10 10 10 10 (parts by Crosslinking agent 1 1 1 1 1 1 1 1 1 weight) Tackifier resin 1 5 5 5 5 5 5 5 5 5 Tackifier resin 2 5 5 5 5 5 5 5 5 5 Fine particle 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Metal having a lower 15 15 15 15 15 15 0 15 15 potential than that of iron (zinc particle) Electroconductive 0.01 0.025 0.05 0.06 0.01 0.5 0.025 0 0 material (CNT) Electroconductive 0 0 0 0 0 0 0 0 4 material (carbon black) Dispersant 0.01 0.025 0.05 0.06 0.01 0.5 0.025 0 0 Polymerization initiator 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Physical Thickness (μm) 600 600 600 600 1500 100 600 600 600 properties of Total light transmittance 99.83 99.77 99.65 99.56 99.83 97.38 99.80 99.90 99.30 pressure- X (%) (per micrometer of sensitive thickness) adhesive layer Total light transmittance 36 25 12 7 8 7 30 55 1 Y (%) (whole thickness) Evaluations Sacrificial protection −750 −850 −860 −900 −750 −950 −500 −550 −750 test: potential (mV) Sacrificial protection Good Good Good Good Good Good Poor Poor Good test: evaluation Adhesive force on 55 50 42 37 60 30 50 55 30 irradiated side (N/25 mm) Adhesive force on other 55 50 34 19 33 16 50 55 6 side of irradiated side (N/25 mm) Adhesive force loss (%) 0 0 20 48 45 48 0 0 80 Adhesive force loss Good Good Good Fair Fair Fair Good Good Poor Evaluations Total evaluation Good Good Good Good Good Good Poor Poor Poor

[0182] Each of the components in Table 1 are as follows.

[0183] Olefin polymer: product name “L-1253”, manufactured by KURARAY CO., LTD., hydrogenated polybutadiene having a (meth)acryloyl group at one end.

[0184] Crosslinking agent: product name “TEAI-1000”, manufactured by NIPPON SODA CO., LTD.

[0185] Tackifier resin 1: product name “ARKON P140”, manufactured by Arakawa Chemical Industries, Ltd., hydrogenated petroleum resin, softening point 140° C.

[0186] Tackifier resin 2: product name “ARKON P100”, manufactured by Arakawa Chemical Industries, Ltd., hydrogenated petroleum resin, softening point 100° C.

[0187] Fine particle: product name “Cel-star Z-27”, manufactured by Tokai Kogyo, K. K., glass balloon

[0188] Zinc particle: product name “Zinc powder #40”, manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., average particle size 50 μm

[0189] Electroconductive material: carbon nanotube (CNT), product name “JENOTUBE 8A”, manufactured by JEIO, average diameter 6 to 9 nm, average length 100 to 200 μm

[0190] Electroconductive material: carbon black, product name “AT-NO.15S”, manufactured by Oriental Industry Co. LTD.

[0191] Dispersant: product name “S-LEC BX-L”, manufactured by SEKISUI CHEMICAL CO., LTD., polyvinyl butyral resin

[0192] Polymerization initiator: 2,2-dimethoxy-2-phenylacetophenone

[0193] The pressure-sensitive adhesive tapes according to Examples 1 to 6 were each an inventive pressure-sensitive adhesive tape, which has pressure-sensitive adhesive layer including a photo-cured acrylic resin, a metal having a lower potential than that of iron, and an electroconductive material other than the metal, and having total light transmittance X and Y within respective predetermined ranges. These pressure-sensitive adhesive tapes were excellent in the sacrificial corrosion resistance, and also showed a small adhesive force loss and therefore a great adhesive force.

[0194] In contrast, the pressure-sensitive adhesive tapes according to Comparative Examples 1 to 3 were each a pressure-sensitive adhesive tape that does not satisfy the requirements of the present invention, and were inferior in at least one of the sacrificial corrosion resistance and the adhesive force.

[Pressure-Sensitive Adhesive Tape According to Second Invention]

[0195] The pressure-sensitive adhesive tape according to the second invention will be described below by way of examples.

[Sacrificial Protection Test]

[0196] The sacrificial protection test was carried out by the following (1) and (2).

(1) A pressure-sensitive adhesive layer with a size of 150 mm×70 mm was attached to a steel plate SS400 (manufactured by TP Giken Corporation, 150 mm×70 mm) as an adherend.
(2) Thereafter, part (3 mm×3 mm) of the pressure-sensitive adhesive layer was cut out, and a NaCl aqueous solution having a concentration of 3 mass % was dropped thereon. A silver/silver chloride electrode was placed such that the tip of the electrode contacts with the NaCl aqueous solution, and the potential was measured using the electrode.

[0197] In the measurement of the potential, a digital multimeter “CDM-11D” (manufactured by CUSTOM corporation) was used as a tester, and the negative electrode thereof was connected with an electrode “HS-205C” (manufactured DKK-TOA CORPORATION) via an electrode clip and used.

[0198] The sacrificial corrosion resistance was evaluated according to the following criteria on the basis of the results obtained by the above sacrificial protection test. “Good” means that the potential is low and that the sacrificial corrosion resistance is thus excellent, and “Poor” means that the potential is high and that the sacrificial corrosion resistance is thus poor.

(Evaluation)

[0199] Good: Potential is −700 mV or less

[0200] Poor: Potential is more than −700 mV

[Adhesive Force]

[0201] For the pressure-sensitive adhesive layer (pressure-sensitive adhesive double sided tape) prepared in each of Examples and Comparative Examples, the adhesive force was measured in the following manner. The measurement of the adhesive force was carried out on the other side of the side irradiated with ultraviolet rays of the pressure-sensitive adhesive layer, and the result is described in Table 2 as the adhesive force on the other side.

[0202] The pressure-sensitive adhesive layer obtained in each example was cut into a size of 100 mm×25 mm, which was adhered to a SUS plate to obtain a measurement sample. The measurement sample was fixed to the chucks of a tensile tester (“TENSILON Universal Material Testing Instrument, manufactured by A&D Company, Limited). Then, the pressure-sensitive adhesive layer was pulled over 60 mm or more at a peeling angle of 180° and a rate of 300 mm/min, and an average value of loads (N) detected over that interval by the load cell was recorded, which was used as the adhesive force (N/25 mm).

[0203] Good: Adhesive force is 25 N/25 mm or more

[0204] Poor: Adhesive force is less than 25 N/25 mm

[Total Light Transmittance]

[0205] The total light transmittance of the pressure-sensitive adhesive layer (pressure-sensitive adhesive double sided tape) prepared in each of Examples and Comparative Examples was measured in the following manner.

[0206] The total light transmittance Y of the pressure-sensitive adhesive layer was measured in accordance with JIS K7361-1. Specifically, the total light transmittance Y was measured in an atmosphere at 23° C. and a humidity of 50% with a haze mater (e.g., Haze Meter NDH4000 manufactured by NIPPON DENSHOKU INDUSTRIES Co., Ltd.).

[0207] The total light transmittance X (%) per micrometer of the thickness was calculated using the following expression from the total light transmittance Y (%) and the thickness T (μm) of the pressure-sensitive adhesive layer.

[00004]$\begin{array}{cc}\underset{\left(\%\right)}{\mathrm{Total}\mathrm{light}\mathrm{transmittance}}Y=100\times {\left(\frac{\mathrm{Total}\mathrm{light}\mathrm{transmittance}X}{100}\right)}^T& \left[\mathrm{Expression}4\right]\end{array}$

[Resistance Value]

[0208] The release sheet was removed from the pressure-sensitive adhesive tape obtained in each of Examples and Comparative example and having a size of 50 mm×50 mm. Then, a resistance meter Hiresta-UP MCP-HT450 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.) was equipped with an electrode URS probe (manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and the electrode was brought into contact with the surface of the pressure-sensitive adhesive tape to measure the resistance.

[Total Evaluation]

[0209] Good: “Good” was given in both the evaluation in the sacrificial protection test and that in the adhesive force loss.

[0210] Poor: “Poor” was given in at least one of the evaluation in the sacrificial protection test and that in the adhesive force loss.

Example 7

[0211] A pressure-sensitive adhesive composition was prepared according to the formulation described in Table 2. Purge with nitrogen gas was carried on the pressure-sensitive adhesive composition to remove dissolved oxygen. Then, a spacer having a thickness of 600 μm was placed on the release-treated side of a release sheet, and the pressure-sensitive adhesive composition was applied to the release-treated side of the release sheet. Then, the applied pressure-sensitive adhesive composition was covered with another release sheet such that the release-treated side thereof was brought into contact with the pressure-sensitive adhesive composition. The release sheets used were each a PET film (thickness 50 μm) that had undergone mold-release treatment with silicone.

[0212] In that state, the lamp intensity of the chemical lamp was adjusted such that the intensity of irradiation with ultraviolet rays was 5 mW/cm.sup.2 on the release sheet on the cover side, and one side was irradiated with ultraviolet rays to obtain an anticorrosive pressure-sensitive adhesive double sided tape consisting of a pressure-sensitive adhesive layer alone with release sheets attached to both sides thereof. The thickness of the pressure-sensitive adhesive layer (that is, the pressure-sensitive adhesive double sided tape) was 600 μm. The results are shown in Table 2.

Examples 8 to 10, Comparative Examples 4 to 7

[0213] An anticorrosive pressure-sensitive adhesive double sided tape was obtained in the same manner as in Example 7, except for preparing a pressure-sensitive adhesive composition according to the formulation described in Table 2. The results are shown in Table 2.

TABLE-US-00002 TABLE 2 Example Comparative Example 7 8 9 10 4 5 6 7 Pressure- 2-Ethylhexyl acrylate 85 85 85 85 85 85 85 85 sensitive n-Butyl acrylate 15 15 15 15 15 15 15 15 adhesive Acrylic acid 5 5 5 5 5 5 5 5 composition Olefin polymer 10 10 10 10 10 10 10 10 (parts by Crosslinking agent 1 1 1 1 1 1 1 1 weight) Tackifier resin 1 5 5 5 5 5 5 5 5 Tackifier resin 2 5 5 5 5 5 5 5 5 Fine particle 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Metal having a lower 15 15 15 15 15 15 0 15 potential than that of iron (zinc particle) Electroconductive 0.01 0.025 0.15 0 0 0 0.01 0 material (CNT (1)) Electroconductive 0 0 0 0.025 0 0 0 0 material (CNT (2)) Electroconductive 0 0 0 0 4 2 0 0 material (carbon black) Dispersant 0.01 0.025 0.15 0.025 0 0 0.01 0 Polymerization initiator 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Physical Thickness (μm) 600 600 600 600 600 600 600 600 properties of Total light transmittance 99.83 99.77 99.25 99.73 99.30 99.50 99.87 99.90 pressure- X (%) (per micrometer of sensitive thickness) adhesive layer Resistance value (Ω) 1 × 10.sup.15 1 × 10.sup.14 1 × 10.sup.11 1 × 10.sup.14 1 × 10.sup.8 1 × 10.sup.10 1 × 10.sup.14 1 × 10.sup.15 Evaluations Sacrificial protection test: −750 −850 −860 −800 −750 −600 −500 −550 potential (mV) Sacrificial protection test: Good Good Good Good Good Poor Poor Poor evaluation Adhesive force on other side 55 50 40 50 6 40 60 55 of irradiated side (N/25 mm) Adhesive force: evaluation Good Good Good Good Poor Good Good Good Total evaluation Good Good Good Good Poor Poor Poor Poor

[0214] Each of the components in Table 2 are as follows.

[0215] Olefin polymer: product name “L-1253”, manufactured by KURARAY CO., LTD., hydrogenated polybutadiene having a (meth)acryloyl group at one end.

[0216] Crosslinking agent: product name “TEAI-1000”, manufactured by NIPPON SODA CO., LTD.

[0217] Tackifier resin 1: product name “ARKON P140”, manufactured by Arakawa Chemical Industries, Ltd., hydrogenated petroleum resin, softening point 140° C.

[0218] Tackifier resin 2: product name “ARKON P100”, manufactured by Arakawa Chemical Industries, Ltd., hydrogenated petroleum resin, softening point 100° C.

[0219] Fine particle: product name “Cel-star Z-27”, manufactured by Tokai Kogyo, K. K., glass balloon

[0220] Zinc particle: product name “Zinc powder #40”, manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., average particle size 50 μm

[0221] Electroconductive material (CNT (1)): carbon nanotube (CNT), product name “JENOTUBE 8A”, manufactured by JEIO, average diameter 6 to 9 nm, average length 100 to 200 μm

[0222] Electroconductive material (CNT (2)): carbon nanotube (CNT), product name “JENOTUBE 10A”, manufactured by JEIO, average diameter 6 to 15 nm, average length 50 to 200 μm

[0223] Electroconductive material: carbon black, product name “AT-NO.15S”, manufactured by Oriental Industry Co. LTD.

[0224] Dispersant: product name “S-LEC BX-L”, manufactured by SEKISUI CHEMICAL CO., LTD., polyvinyl butyral resin

[0225] Polymerization initiator: 2,2 -dimethoxy-2 -phenylacetophenone

[0226] The pressure-sensitive adhesive tapes according to Examples 7 to 10 were each a pressure-sensitive adhesive tape having pressure-sensitive adhesive layer containing a metal having a lower potential than that of iron and carbon nanotube, and showed a great adhesive force and high sacrificial corrosion resistance.

[0227] In contrast, the pressure-sensitive adhesive tapes according to Comparative Examples 4 to 7 were each a pressure-sensitive adhesive tape that does not contain at least one of the metal having a lower potential than that of iron and carbon nanotube, which does not satisfy the requirements of the present invention, and were inferior in at least one of the sacrificial corrosion resistance and the adhesive force.