Pressure-sensitive tape having a plurality of adhesive layers

• US 4,260,659 A
• Filed: 06/18/1979
• Issued: 04/07/1981
• Est. Priority Date: 06/18/1979
• Status: Expired due to Term

• Current Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Original Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Inventors: Gobran, Ramsis
• Primary Examiner(s): Lesmes, George F.
• Assistant Examiner(s): Thomas, Alexander S.
• Application Number:
  US06/049,415
• Time in Patent Office: 659 Days
• Field of Search: 428/40, 428/212, 428/214, 428/217, 428/218, 428/343, 428/354, 428/220, 428/246, 428/261, 428/262, 428/263, 428/336, 428/339, 428/356, 427/207 D, 427/207 R, 427/207.1, 427/208.8
• US Class Current: 428/217
• CPC Class Codes: C09J 2301/208 the adhesive layer being constituted by at least two or more adjacent or superposed adhesive layers, e.g. multilayer adhesive
• CPC Class Codes: C09J 2301/302 the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
• CPC Class Codes: C09J 7/38 Pressure-sensitive adhesives [PSA]
• CPC Class Codes: Y10T 428/24983 Hardness
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/269 including synthetic resin or polymer layer or component
• CPC Class Codes: Y10T 428/2848 Three or more layers
• CPC Class Codes: Y10T 428/2857 including metal or compound thereof or natural rubber
• CPC Class Codes: Y10T 442/2041 Two or more non-extruded coatings or impregnations
• CPC Class Codes: Y10T 442/2754 Pressure-sensitive adhesive

Abstract

A pressure-sensitive adhesive tape which not only conforms well and adheres quickly to irregular substrates but also possesses excellent shear adhesion performance. These properties, normally mutually exclusive, are achieved through use of superposed plural pressure-sensitive adhesive strata, the outer stratum being significantly softer than the one lying immediately beneath it.

Claims

1. In a normally tacky and pressure-sensitive adhesive tape of the type wherein a layer of normally tacky and pressure-sensitive adhesive is coated over and adhered to a flexible sheet material,

the improvement wherein the pressure-sensitive adhesive layer comprises a plurality of superposed and firmly united adhesive strata selected from the same general class of adhesives, each having a thickness of about 15 to 60 micrometers, the thickness of said layer being 40-120 micrometers if only two strata are present and 60-180 micrometers if three strata are present, the exposed adhesive stratum having a 10-second shear creep compliance of at least about 5×

10^-6 cm² /dyne and the immediately underlying adhesive stratum having a 10-second shear creep compliance of not more than about 2×

10^-6 cm² /dyne,

whereby the tape has a quick stick value of at least about 100 grams per centimeter width, a shear adhesion value of at least 3 minutes, and a contamination tolerance of at least about 15 grams per centimeter width.

2. The tape of claim 1, wherein a third adhesive stratum is interposed between the backing and said underlying adhesive stratum, said third adhesive stratum having a 10-second shear creep compliance of more than 3.5×

10^-6 cm² /dyne.

3. In normally tacky and pressure-sensitive adhesive tape of the type wherein a layer of normally tacky and pressure-sensitive adhesive is coated over and adhered to a flexible sheet material,

the improvement wherein the pressure-sensitive adhesive layer comprises a plurality of superposed and firmly united adhesive strata selected from the same general class of adhesives, each having a thickness about 15 to 60 micrometers, the thickness of said layer being 40-120 micrometers if only two strata are present and 60-180 micrometers if three strata are present, the exposed adhesive stratum having a 10-second shear creep compliance of at least about 5×

10^-6 cm² /dyne and the immediately underlying adhesive stratum having a 10-second shear creep compliance of not more than about 2×

10^-6 cm² /dyne, all of said adhesive strata being rubber-resin compositions,

whereby the tape has a quick stick value of at least about 100 grams per centimeter width, a shear adhesion value of at least 3 minutes, and a contamination tolerance of at least about 15 grams per centimeter width.

4. In normally tacky and pressure-sensitive adhesive tape of the type wherein a layer of normally tacky and pressure-sensitive adhesive is coated over and adhered to a flexible sheet material,

the improvement wherein the pressure-sensitive adhesive layer comprises a plurality of superposed and firmly united adhesive strata selected from the same general class of adhesives and each having a thickness of about 15 to 60 micrometers, the thickness of said layer being 40-120 micrometers if only two strata are present and 60-180 micrometers if three strata are present, the exposed adhesive stratum having a 10-second shear creep compliance of at least about 5×

10^-6 cm² /dyne and the immediately underlying adhesive stratum having a 10-second shear creep compliance of not more than 2×

10^-6 cm² /dyne, all of said adhesive strata being acrylate compositions,

whereby the tape has a quick stick value of at least about 100 grams per centimeter width, a shear adhesion value of at least 3 minutes, and a contamination tolerance of at least about 15 grams per centimeter width.

5. The tape of claim 4 wherein the acrylate compositions consist essentially of iso-octyl acrylate:

acrylic acid copolymers.

6. The tape of claim 4 wherein a third adhesive stratum is interposed between the backing and said underlying adhesive stratum, said third adhesive stratum having a 10-second shear creep compliance of more than 3.5×

10^-6 cm² /dyne.

7. The tape of claim 6 wherein the backing is a cloth.

8. The tape of claim 6 wherein the backing is a polymeric film.