Process of making a unified pressure-sensitive adhesive tape

• US 4,894,259 A
• Filed: 06/28/1988
• Issued: 01/16/1990
• Est. Priority Date: 08/29/1986
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Kuller, Douglas H.
• Primary Examiner(s): PIANALTO, BERNARD D
• Application Number:
  US07/212,596
• Time in Patent Office: 567 Days
• Field of Search: 427/54.1, 427/208.8, 427/333, 428/220, 428/336, 428/345, 428/354
• US Class Current: 427/208.8
• 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]

Abstract

A process of making pressure-sensitive adhesive tape comprising a plurality of concurrently coated superimposed layers, at least one outer layer being a pressure-sensitive adhesive layer, contiguous layers defining an interface therebetween, each of the layers comprising a photopolymerized matrix of polymeric chains; the polymeric chains extending from the matrix of one of the layers through the interface into the matrix of a contiguous layer; the polymeric chains comprising photopolymerized monomers having migrated from the matrix of each contiguous layer prior to photopolymerization, whereby the layers cannot be delaminated.

Claims

1. A process for making a pressure-sensitive adhesive tape comprising a plurality of concurrently coated simultaneously photopolymerized superimposed layers, said layers having been simultaneously photopolymerized, at least one outer layer being a pressure-sensitive adhesive layer, said pressure-sensitive adhesive layer comprising at least one alkyl acrylate ester of a nontertiary alcohol, and a photoinitiator, contiguous layers defining an interface therebetween, each of said layers comprising a photopolymerized matrix of polymeric chains;

said polymeric chains extending from the matrix of one of said layers through said interface into the matrix of a contiguous layer;

said polymeric chains comprising polymerized monomers having migrated from the matrix of each contiguous layers, said process comprising the steps of;

(1) preparing a plurality of coatable compositions, each of said coatable compositions comprising at least one photopolymerizable monomer;

at least one of said coatable compositions being curable to a pressure-sensitive adhesive state, monomers of each of said coatable compositions being copolymerizable when blended and subjected to photopolymerization conditions;

(2) concurrently coating said coatable compositions to provide a plurality of superimposed layers with contiguous layers defining an interface therebetween, with one composition which is curable to a pressure-sensitive adhesive state being coated as an outer layer;

(3) permitting migration of photopolymerizable monomers through said interface between contiguous layers; and

(4) subjecting said superimposed layers to irradiation to simultaneously photopolymerize said monomers in each layer, and to provide polymeric chains comprised of copolymers of photopolymerizable monomers originating from contiguous layers extending through said interface therebetween;

thereby to produce a tape having layers which cannot be delaminated.

3. A process according to claim 1 for making a pressure-sensitive tape wherein at least one layer further comprises from about 5% to about 65% volume percent ultraviolet transparent microbubbles having a specific gravity of no more than 1.0, said process comprising the steps of:

(1) preparing a coatable composition having said ultraviolet-transparent microbubbles dispersed therein which comprises at least one monomer photopolymerizable to a pressure-sensitive adhesive state;

(2) preparing one or more coatable compositions which are microbubble-free, and comprise at least one photopolymerizable monomer, said monomer being copolymerizable with the monomer in step 1 when blended and subjected to photopolymerization conditions;

(3) concurrently coating said coatable compositions of step 1, and step 2 onto a low-adhesion carrier to form superimposed layers, said contiguous layers defining an interface therebetween;

(4) permitting migration of photopolymerizable monomers through said interface between said contiguous layers; and

(5) subjecting said superimposed layers to irradiation to simultaneously photopolymerize the monomers in each layer, and to provide polymeric chains of copolymers of polymerizable monomers originating from contiguous layers extending through the interface therebetween;

thereby to produce a tape having layers which cannot be delaminated.

2. A process according to claim for making a pressure-sensitive adhesive tape having an adhesive layer comprising from about 40% to about 95% isooctyl acrylate, and from 5% to about 60% of a polar copolymerizable monomer selected from the group consisting of N-vinyl pyrrolidone and acrylic acid, said process comprising the steps of:

(1) preparing one or more coatable compositions which are photopolymerizable to yield a non-tacky polymeric material;

(2) preparing a coatable composition containing at least one monomer which is photopolymerizable to a pressure-sensitive adhesive state, said monomer being copolymerizable with the monomer in step 1 when blended and subjected to photopolymerization conditions;

(3) concurrently coating said coatable compositions of step 1, and step 2 onto a carrier to form superimposed layers, contiguous layer defining an interface therebetween;

(4) permitting migration of photopolymerizable monomers through said interface between said contiguous layers; and

(5) subjecting said superimposed layers to irradiation to simultaneously photopolymerize said monomers in each layer, and to provide polymeric chains comprised of copolymers of photopolymerizable monomers originating from contiguous layers extending through said interface therebetween;

thereby to produce a tape having which cannot be delaminated.