Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
2001-12-18
2004-05-04
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S3550CN, C428S447000, C428S448000, C525S477000, C528S038000
Reexamination Certificate
active
06730397
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to silicone adhesives, articles, and methods of making and using. The adhesives are particularly useful on articles such as tapes, particularly foam tapes, for example.
BACKGROUND
Pressure sensitive adhesives containing polydiorganosiloxane polyurea copolymers and a compatible tackifier are well known. They have a variety of applications because they can possess one or more of the following properties: high thermal stability; high oxidative stability; permeability to many gases; low surface energy; low index of refraction; low hydrophilicity; dielectric properties; biocompatibility; and adhesive properties. Examples of such pressure sensitive adhesives are disclosed in U.S. Pat. Nos. 5,461,134 (Leir et al.), 5,512,650 (Leir et al.), 5,475,124 (Mazurek et al.), as well as International Publication Nos. WO 96/30426 (3M Co., St. Paul, Minn.), WO 96/34028 (3M Co.), WO 96/34029 (3M Co.), and WO 98/15602 (3M Co.).
Although silicone pressure sensitive adhesives are known to adhere to a wide variety of substrates, there is still a need for adhesives and adhesive articles, particularly tapes such as foam tapes, that provide an effective peel strength and shear strength to such substrates, without the need for a primer or other chemical or physical surface treatment of the substrate.
SUMMARY OF THE INVENTION
The present invention provides pressure sensitive adhesives (PSAs), adhesive articles, and methods. Preferably, the articles are in the form of tapes, such as foam tapes, for example. Significantly, the PSAs include a polydiorganosiloxane polyurea copolymer and a silicone tackifying resin with little or no silanol (Si—OH) functionality, yet provide high and stable adhesion to a wide variety of substrates. Prior to this it was not appreciated that for silicone polyurea-based pressure sensitive adhesive, little or no silanol functionality in the silicone tackifying resin could enhance adhesion.
The adhesive of the present invention can form a discontinuous layer (e.g., pattern) on the substrate (e.g., backing of a tape) or it can form a continuous layer on at least one major surface thereof. It is a pressure sensitive adhesive, which unlike a heat activated adhesive, typically uses pressure to engage adhesion at room temperature (about 20° C. to about 30° C.) and does not require the use of a heating device.
Generally, the pressure sensitive adhesives of the present invention include: a silicone tackifying resin having no greater than about 1.5% by weight (wt-%) Si—OH functional groups (preferably, no greater than about 1.2 wt-%, more preferably, no greater than about 1.0 wt-%, and most preferably, no greater than about 0.8 wt-%), based on the total weight of the silicone tackifying resin; and a polydiorganosiloxane polyurea copolymer. Significantly, such pressure sensitive adhesives, as a result of the low silanol content in the silicone tackifying resin, adhere to both high and low surface energy materials better than conventional silicone adhesives with higher silanol content. Methods of making such adhesives are also provided.
In one embodiment, the present invention provides a silicone pressure sensitive adhesive that includes: a silicone tackifying resin having no greater than about 1.5 percent by weight (wt-%) Si—OH functional groups; and a polydiorganosiloxane polyurea copolymer. Preferably, the pressure sensitive adhesive adheres to both high and low surface energy materials as well as those in between, wherein the high surface energy material has a surface energy above about 70 dynes/centimeter (dynes/cm) and the low surface energy material has a surface energy below about 50 dynes/cm.
In another embodiment, the pressure sensitive adhesive includes: a silicone tackifying resin having no greater than about 1.5 wt-% Si—OH functional groups; and a polydiorganosiloxane polyurea copolymer; wherein the pressure sensitive adhesive satisfies at least one of the following criteria: the pressure sensitive adhesive adheres to both high and low surface energy materials as well as those in between, wherein the high surface energy material has a surface energy above about 70 dynes/cm and the low surface energy material has a surface energy below about 50 dynes/cm; when the adhesive is disposed on a 50.8-micrometer thick PET backing at an adhesive thickness of 50.8 micrometers to form a single-coated tape and adhered to a high density polyethylene coupon, the tape displays a 180° peel force of at least about 55 Newtons per decimeter (N/dm) when measured at a rate of 30.5 cm/min at room temperature after a dwell time of one minute at room temperature; when the adhesive is disposed on a 50.8-micrometer thick PET backing at an adhesive thickness of 50.8 micrometers to form a single-coated tape and adhered to a stainless steel coupon, the tape displays a 180° peel force of at least about 60 N/dm when measured at a rate of 30.5 centimeters/minute (cm/min) at room temperature after a dwell time of one minute at room temperature; when the adhesive is disposed on a 1 millimeter thick 87.5/12.5 isooctyl acrylate/acrylic acid foam backing at an adhesive thickness of 50.8 micrometers to form a double-coated tape and adhered to a high density polyethylene coupon, the tape displays a 90° peel force of at least about 230 N/dm when measured at a rate of 30.5 cm/min at room temperature after a dwell time of 72 hours at room temperature; when the adhesive is disposed on a 1 millimeter thick 87.5/12.5 isooctyl acrylate/acrylic acid foam backing at an adhesive thickness of 50.8 micrometers to form a double-coated tape and adhered to a stainless steel coupon, the tape displays a 90° peel force of at least about 300 N/dm when measured at a rate of 30.5 cm/min at room temperature after a dwell time of 72 hours at room temperature; or when the adhesive is disposed on a 1 millimeter thick 87.5/12.5 isooctyl acrylate/acrylic acid foam backing at an adhesive thickness of 50.8 micrometers to form a double-coated tape and adhered to a polypropylene coupon, the tape displays a 90° peel force of at least about 400 N/dm when measured at a rate of 30.5 cm/min at room temperature after a dwell time of 72 hours at room temperature.
In yet another embodiment, the present invention provides a pressure sensitive adhesive that includes: a silicone tackifying resin having no greater than about 1.5 wt-% Si—OH functional groups silicone and an M/Q ratio of at least about 0.7:1.0; and a polydiorganosiloxane polyurea copolymer; wherein the pressure sensitive adhesive adheres to both high and low surface energy materials as well as those in between, wherein the high surface energy material has a surface energy above about 70 dynes/cm and the low surface energy material has a surface energy below about 50 dynes/cm.
In still another embodiment, a pressure sensitive adhesive includes: a silicone tackifying resin having no greater than about 1.5 wt-% Si—OH functional groups silicone and an M/Q ratio of at least about 0.7:1.0; and a polydiorganosiloxane polyurea copolymer including the following repeating unit:
where: each R is independently an alkyl moiety, a vinyl moiety or higher alkenyl moiety, a cycloalkyl moiety, an aryl moiety, or a fluorine-containing group; each Z is independently a polyvalent moiety that is an arylene moiety, an aralkylene moiety, an alkylene moiety, or a cycloalkylene moiety; each Y is independently a polyvalent moiety that independently is an alkylene moiety, an aralkylene moiety or an arylene moiety; each E is independently hydrogen, an alkyl moiety of 1 to 10 carbon atoms, phenyl, or a moiety that completes a ring structure including Y to form a heterocycle; each A is independently oxygen or —N(G)—, wherein each G is independently hydrogen, an alkyl moiety of 1 to 10 carbon atoms, phenyl, or a moiety that completes a ring structure including B to form a heterocycle; B is an alkylene, aralkylene, cycloalkylene, phenylene, polyalkylene, polyalkylene oxide, copolymers, or mixtures thereof, or a moiety completing a ring structure including A to form a heterocycle;
Kremer Anthony M.
Lunsford Duane A.
Melancon Kurt C.
Sherman Audrey A.
Tumey Michael L.
3M Innovative Properties Company
Bardell Scott A.
Dawson Robert
Keehan Christopher
Pastirik Daniel R.
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