U.S. patent application number 14/484890 was filed with the patent office on 2014-12-25 for blends of block copolymer and acrylic adhesives.
This patent application is currently assigned to 3M Innovative Properties Company. The applicant listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to Gregory B. Gadbois, Robert D. Waid, Panu K. Zoller.
Application Number | 20140377535 14/484890 |
Document ID | / |
Family ID | 39492584 |
Filed Date | 2014-12-25 |
United States Patent
Application |
20140377535 |
Kind Code |
A1 |
Waid; Robert D. ; et
al. |
December 25, 2014 |
Blends of Block Copolymer and Acrylic Adhesives
Abstract
Pressure sensitive adhesive compositions containing 92 to 99.9
parts of a block copolymer adhesive composition and 0.1 to less
than 8 parts of an acrylic adhesive composition are described.
Tapes including such adhesives, and methods of making such tapes
are also described.
Inventors: |
Waid; Robert D.; (Oakdale,
MN) ; Zoller; Panu K.; (River Falls, WI) ;
Gadbois; Gregory B.; (Woodville, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
ST. PAUL |
MN |
US |
|
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
39492584 |
Appl. No.: |
14/484890 |
Filed: |
September 12, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12514865 |
May 14, 2009 |
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PCT/US2007/083741 |
Nov 6, 2007 |
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14484890 |
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60868975 |
Dec 7, 2006 |
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Current U.S.
Class: |
428/317.7 ;
156/244.11; 264/174.11; 264/477; 428/521 |
Current CPC
Class: |
C09J 2453/00 20130101;
Y10T 428/249983 20150401; C09J 2433/00 20130101; B29C 48/21
20190201; B29K 2105/0097 20130101; B29C 48/0021 20190201; B32B 3/26
20130101; B29K 2033/12 20130101; C09J 153/02 20130101; B29K 2096/04
20130101; B32B 7/12 20130101; B32B 27/065 20130101; C09J 2433/006
20130101; B32B 2270/00 20130101; B29K 2105/0085 20130101; B32B
2250/03 20130101; C09J 133/14 20130101; B32B 2250/02 20130101; C09J
7/26 20180101; Y10T 428/31931 20150401; B32B 2405/00 20130101; C08L
33/14 20130101; B32B 27/06 20130101; C08L 33/06 20130101; B29K
2009/00 20130101; B32B 2250/04 20130101; B29C 35/10 20130101; B29K
2105/0002 20130101; B29L 2009/00 20130101; Y10T 428/249985
20150401; B29K 2025/00 20130101; C09J 133/08 20130101; C08L 53/02
20130101; C08L 2205/02 20130101; Y10T 428/31855 20150401; C09J
153/02 20130101; C08L 33/06 20130101; C09J 153/02 20130101; C08L
33/06 20130101; C08L 53/02 20130101; C09J 2433/00 20130101; C09J
2453/00 20130101; C09J 2453/00 20130101; C09J 2433/00 20130101 |
Class at
Publication: |
428/317.7 ;
428/521; 264/174.11; 156/244.11; 264/477 |
International
Class: |
C09J 153/02 20060101
C09J153/02; B32B 3/26 20060101 B32B003/26; B29C 35/10 20060101
B29C035/10; B29C 47/06 20060101 B29C047/06; B29C 47/00 20060101
B29C047/00; B32B 27/06 20060101 B32B027/06; B32B 7/12 20060101
B32B007/12 |
Claims
1. A method of making a tape comprising extruding a foam backing
and coextruding a first pressure sensitive adhesive to form a first
adhesive skin bonded to a first major surface of the foam backing,
wherein the pressure sensitive adhesive comprises: (A) 92 to 99.9
parts of a block copolymer adhesive composition comprising: (a) a
first block copolymer comprising (i) at least one rubbery block
comprising a first polymerized conjugated diene, a hydrogenated
derivative thereof, or combinations thereof; and (ii) at least one
glassy block comprising a first polymerized monovinyl aromatic
monomer; and (B) 0.1 to less than 8 parts of an acrylic adhesive
composition comprising: (i) 70 to 100 parts of at least one acrylic
or methacrylic ester of a non-tertiary alkyl alcohol, wherein the
non-tertiary alkyl alcohol contains 4 to 20 carbon atoms; and (ii)
10 to 30 parts of a copolymerized reinforcing monomer.
2. The method of claim 1, further comprising extruding the second
adhesive to form a second adhesive skin bonded to the second major
surface of the foam backing.
3. The method of claim 2, wherein extruding the second adhesive
comprises coextruding the second adhesive with the first pressure
sensitive adhesive and the foam backing.
4. The method claim 1, wherein the second adhesive is a pressure
sensitive adhesive comprising: (A) 92 to 99.9 parts of a block
copolymer adhesive composition comprising: (a) a first block
copolymer comprising (i) at least one rubbery block comprising a
first polymerized conjugated diene, a hydrogenated derivative
thereof, or combinations thereof; and (ii) at least one glassy
block comprising a first polymerized monovinyl aromatic monomer;
and (B) 0.1 to less than 8 parts of an acrylic adhesive composition
comprising: (i) 70 to 100 parts of at least one acrylic or
methacrylic ester of a non-tertiary alkyl alcohol, wherein the
non-tertiary alkyl alcohol contains 4 to 20 carbon atoms; and (ii)
10 to 30 parts of a copolymerized reinforcing monomer.
5. A method of making the tape according to claim 1, comprising
providing the foam backing, and applying a first adhesive
composition comprising the first pressure sensitive adhesive to the
first surface of the foam backing.
6. The method of claim 5, wherein applying the first adhesive
composition comprises laminating.
7. The method of claim 6 wherein applying first adhesive
composition comprises coating, optionally wherein the method
further comprises crosslinking the first adhesive composition,
optionally wherein crosslinking the first adhesive composition
comprises radiation crosslinking.
8. The method according to claim 5, wherein the first adhesive
composition is a solvent-based adhesive, and the method further
comprises drying the first adhesive composition.
9. The method according to claim 5, further comprising applying a
second adhesive composition to the second surface of the foam.
10. The method according to claim 9, wherein the second adhesive
composition comprises a pressure sensitive adhesive according to
any one of claims 1-30.
11. The method of claim 9, wherein applying the second adhesive
composition comprises laminating.
12. The method of claim 9 wherein applying second adhesive
composition comprises coating, optionally wherein the method
further comprises crosslinking the second adhesive composition,
optionally wherein crosslinking the second adhesive composition
comprises radiation crosslinking.
13. The method according to claim 9, wherein the second adhesive
composition is a solvent-based adhesive, and the method further
comprises drying the second adhesive composition.
14. A bonded composite comprising: a first substrate having a first
surface; a second substrate having a second surface; and a bonding
interface between the first surface of the first substrate and the
second surface of the second substrate, wherein the bonding
interface comprises a pressure sensitive adhesive comprising: (A)
92 to 99.9 parts of a block copolymer adhesive composition
comprising: (a) a first block copolymer comprising (i) at least one
rubbery block comprising a first polymerized conjugated diene, a
hydrogenated derivative thereof, or combinations thereof; and (ii)
at least one glassy block comprising a first polymerized monovinyl
aromatic monomer; and (B) 0.1 to less than 8 parts of an acrylic
adhesive composition comprising: (i) 70 to 100 parts of at least
one acrylic or methacrylic ester of a non-tertiary alkyl alcohol,
wherein the non-tertiary alkyl alcohol contains 4 to 20 carbon
atoms; and (ii) 10 to 30 parts of a copolymerized reinforcing
monomer.
15. The bonded composite according to claim 14, wherein the first
surface has a surface energy of less than 35 dyne per
centimeter.
16. A bonded composite comprising: a first substrate having a first
surface; a second substrate having a second surface; and a bonding
interface between the first surface of the first substrate and the
second surface of the second substrate, wherein the bonding
interface comprises a tape according to claim 1.
17. The bonded composite according to claim 16, wherein the first
surface has a surface energy of less than 35 dyne per centimeter.
Description
FIELD
[0001] The present disclosure relates to block copolymer-based
adhesives. Particularly, acrylic modified, block copolymer pressure
sensitive adhesives.
BACKGROUND
[0002] Adhesives and tapes are commonly used to bond two substrates
together to form a bonded composite. While a vast array of
adhesives and tapes are available, advances in substrates and end
use requirements continues to drive a need for new adhesive
formulations and tape constructions. In addition to performance
properties, environmental regulations and processing costs also
influence product formulation requirements. For example, in some
applications it may be desirable to use a hot melt adhesive rather
than a solvent-based adhesive.
[0003] While some efforts are directed at the identification and
development of new materials for use in adhesive formulations, much
progress can still be made by identifying, selecting, and combining
the proper proportions of existing raw materials to arrive at
useful adhesives and tapes.
SUMMARY
[0004] Briefly, in one aspect, the present disclosure provides a
pressure sensitive adhesive composition comprising 92 to 99.9 parts
of a block copolymer adhesive composition and 0.1 to less than 10
parts of an acrylic adhesive composition. The block copolymer
adhesive composition comprises a first block copolymer comprising
(i) at least one rubbery block comprising a first polymerized
conjugated diene, a hydrogenated derivative thereof, or
combinations thereof; and (ii) at least one glassy block comprising
a first polymerized monovinyl aromatic monomer. The acrylic
adhesive composition comprises 70 to 100 parts of at least one
acrylic or methacrylic ester of a non-tertiary alkyl alcohol,
wherein the non-tertiary alkyl alcohol contains 4 to 20 carbon
atoms; and 0 to 30 parts of a copolymerized reinforcing
monomer.
[0005] In some embodiments, the first block copolymer is a
multi-arm block copolymer of the formula Q.sub.n-Y, wherein Q
represents an arm of the multi-arm block copolymer, n represents
the number of arms and is a whole number of at least 3; and Y is
the residue of a multifunctional coupling agent. Each arm, Q,
independently has the formula R-G wherein R represents the rubbery
block; and G represents the glassy block. In some embodiments, the
first block copolymer is a polymodal, asymmetric star block
copolymer.
[0006] In some embodiments, the pressure sensitive adhesive further
comprises a second block copolymer comprising at least one rubbery
block comprising a polymerized second conjugated diene, a
hydrogenated derivative thereof, or combinations thereof; and at
least one glassy block comprising a second polymerized monovinyl
aromatic monomer. In some embodiments, the second block copolymer
is a linear block copolymer.
[0007] In some embodiments, the pressure sensitive adhesive further
comprises a first high Tg tackifier having a Tg of at least 60
degrees C., wherein the first high Tg tackifier is compatible with
at least one rubbery block. In some embodiments, the block
copolymer adhesive composition further comprises a second high Tg
tackifier having a Tg of at least 60 degrees C., wherein the second
high Tg tackifier is compatible with the at least one glassy
block.
[0008] In some embodiments, the pressure sensitive adhesive is a
hot melt adhesive. In some embodiments, the pressure sensitive
adhesive is a solvent-based adhesive.
[0009] In another aspect, the present disclosure provides a tape
comprising a foam backing having a first major surface and a second
major surface; and a first adhesive skin bonded to the first major
surface, wherein the first adhesive skin comprises a first pressure
sensitive adhesive according to any one of the preceding claims. In
some embodiments, the tape further comprises a second adhesive skin
bonded to the second major surface.
[0010] In some embodiments, the backing is a foam backing In some
embodiments, the foam comprises a thermoplastic foam. In some
embodiments, the foam comprises a thermoset foam.
[0011] In yet another aspect, the present disclosure provides a
method of making a tape. In some embodiments, the method comprises
extruding a foam backing and coextruding a first pressure sensitive
adhesive to form the first adhesive skin bonded to the first major
surface of the foam backing In some embodiments, the method further
comprises extruding a second adhesive to form a second adhesive
skin bonded to the second major surface of the foam backing.
[0012] In some embodiments, the method comprises providing a foam
backing, and applying a first adhesive composition comprising the
first pressure sensitive adhesive to the first surface of the foam
backing. In some embodiments, applying the first adhesive
composition comprises laminating.
[0013] In some embodiments, applying the first adhesive composition
comprises coating, optionally wherein the method further comprises
crosslinking the first adhesive composition, optionally wherein
crosslinking the first adhesive composition comprises radiation
crosslinking.
[0014] In another aspect, the present disclosure provides a bonded
composite comprising a first substrate having a first surface; a
second substrate having a second surface; and a bonding interface
between the first surface of the first substrate and the second
surface of the second substrate, wherein the bonding interface
comprises a pressure sensitive adhesive according to the present
disclosure. In some embodiments, the first surface has a surface
energy of less than 35 dyne per centimeter.
[0015] The above summary of the present disclosure is not intended
to describe each embodiment of the present invention. The details
of one or more embodiments of the invention are also set forth in
the description below. Other features, objects, and advantages of
the invention will be apparent from the description and from the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates a tape according to some embodiments of
the present disclosure.
[0017] FIG. 2 illustrates a bonded composite according to some
embodiments of the present disclosure.
DETAILED DESCRIPTION
[0018] In one aspect, the present disclosure provides a pressure
sensitive adhesive composition comprising both a block copolymer
adhesive composition and an acrylic adhesive composition. In some
embodiments, the pressure sensitive adhesive further comprises one
or more additional block copolymers, one or more tackifiers, other
additives, and combinations thereof.
[0019] In some embodiments, the pressure sensitive adhesive
composition comprises at least about 90 parts, and in some
embodiments, at least about 92 parts, and in some embodiments, at
least about 96 parts of a block copolymer adhesive composition. In
some embodiments, the pressure sensitive adhesive composition
comprises no greater than about 99.9 parts, and in some
embodiments, no greater than about 99 parts, or even no greater
than about 98 parts of a block copolymer adhesive composition. In
some embodiments, the pressure sensitive adhesive composition
comprises 92 to 99.9 parts and, in some embodiments, 96 to 99 parts
of a block copolymer adhesive composition.
[0020] The first block copolymer comprises a rubbery block, R, and
at least one glassy block, G. In some embodiments, the first block
copolymer comprises at least three glassy blocks. In some
embodiments, the first block copolymer comprises between three and
five glassy blocks, inclusive. In some embodiments, the first block
copolymer comprises four glassy blocks.
[0021] In some embodiments, the first block copolymer is a
multi-arm block copolymer having the general formula Q.sub.n-Y,
wherein Q represents an arm of the multi-arm block copolymer; n
represents the number of arms and is a whole number of at least 3;
and Y is the residue of a multifunctional coupling agent. Each arm,
Q, independently has the formula R-G, wherein G represents the
glassy block; and R represents the rubbery block.
[0022] Generally, a rubbery block exhibits a glass transition
temperature (Tg) of less than room temperature. In some
embodiments, the Tg of the rubbery block is less than about
0.degree. C., or even less than about -10.degree. C. In some
embodiments, the Tg of the rubbery block is less than about
-40.degree. C., or even less than about -60.degree. C.
[0023] Generally, a glassy block exhibits a Tg of greater than room
temperature. In some embodiments, the Tg of the glassy block is at
least about 40.degree. C., at least about 60.degree. C., at least
about 80.degree. C., or even at least about 100.degree. C.
[0024] In some embodiments, the rubbery block comprises a
polymerized conjugated diene, a hydrogenated derivative of a
polymerized conjugated diene, or combinations thereof. In some
embodiments, the conjugated dienes comprise 4 to 12 carbon atoms.
Exemplary conjugated dienes include butadiene, isoprene,
ethylbutadiene, phenylbutadiene, piperylene, pentadiene, hexadiene,
ethylhexadiene, and dimethylbutadiene. The polymerized conjugated
dienes may be used individually or as copolymers with each other.
In some embodiments, the conjugated diene is selected from the
group consisting of isoprene, butadiene, ethylene butadiene
copolymers, and combinations thereof.
[0025] In some embodiments, at least one glassy block comprises a
polymerized monovinyl aromatic monomer. In some embodiments, both
glassy blocks of a triblock copolymer comprise a polymerized
monovinyl aromatic monomer. In some embodiments, the monovinyl
aromatic monomers comprise 8 to 18 carbon atoms. Exemplary
monovinyl aromatic monomers include styrene, vinylpyridine, vinyl
toluene, alpha-methyl styrene, methyl styrene, dimethylstyrene,
ethylstyrene, diethyl styrene, t-butylstyrene, di-n-butylstyrene,
isopropylstyrene, other alkylated-styrenes, styrene analogs, and
styrene homologs. In some embodiments, the monovinyl aromatic
monomer is selected from the group consisting of styrene,
styrene-compatible monomers or monomer blends, and combinations
thereof.
[0026] As used herein, "styrene-compatible monomers or monomer
blends" refers to a monomer or blend of monomers, which may be
polymerized or copolymerized, that preferentially associate with
polystyrene or with the polystyrene endblocks of a block copolymer.
The compatibility can arise from actual copolymerization with
monomeric styrene; solubility of the compatible monomer or blend,
or polymerized monomer or blend in the polystyrene phase during hot
melt or solvent processing; or association of the monomer or blend
with the styrene-rich phase domain on standing after
processing.
[0027] In the general formula for some multi-arm block copolymers
of the present disclosure, Q.sub.n-Y, n represents the number of
arms and is a whole number of at least 3, i.e., the multi-arm block
copolymer is a star block copolymer. In some embodiments, n is
ranges from 3-10. In some embodiments, n ranges from 3-5. In some
embodiments, n is 4. In some embodiments, n is equal to 6 or
more.
[0028] In some embodiments, the first block copolymer is a
polymodal block copolymer. As used herein, the term "polymodal"
means that the copolymer comprises glassy blocks having at least
two different molecular weights. Such a block copolymer may also be
characterized as having at least one "high" molecular weight glassy
block, and at least one "low" molecular weight glassy block,
wherein the terms high and low are used relative to each other. In
some embodiments the ratio of the number average molecular weight
of the high molecular weight glassy block, (Mn).sub.H, relative to
the number average molecular weight of the low molecular weight
glassy block,(Mn).sub.L, is at least about 1.25.
[0029] In some embodiments, (Mn).sub.H ranges from about 5,000 to
about 50,000. In some embodiments, (Mn).sub.H is at least about
8,000, and in some embodiments at least about 10,000. In some
embodiments, (Mn).sub.H is no greater than about 35,000. In some
embodiments, (Mn).sub.L ranges from about 1,000 to about 10,000. In
some embodiments, (Mn).sub.L is at least about 2,000, and, in some
embodiments, at least about 4,000. In some embodiments, (Mn).sub.L
is less than about 9,000, and, in some embodiments, less than about
8,000.
[0030] In some embodiments, the first block copolymer is an
asymmetric block copolymer. As used herein, the term "asymmetric"
means that the arms of the block copolymer are not all identical.
Generally, a polymodal block copolymer is an asymmetric block
copolymer (i.e., a polymodal asymmetric block copolymer) as not all
arms of a polymodal block copolymer are identical since the
molecular weights of the glassy blocks are not all the same. In
some embodiments, the block copolymers of the present disclosure
are polymodal, asymmetric block copolymers. Methods of making
asymmetric, polymodal block copolymers are described in, e.g., U.S.
Pat. No. 5,296,547.
[0031] Generally, the multifunctional coupling agent may be any
polyalkenyl coupling agent or other material known to have
functional groups that can react with carbanions of the living
polymer to form linked polymers. The polyalkenyl coupling agent may
be aliphatic, aromatic, or heterocyclic. Exemplary aliphatic
polyalkenyl coupling agents include polyvinyl and polyalkyl
acetylenes, diacetylenes, phosphates, phosphites, and
dimethacrylates (e.g., ethylene dimethacrylate). Exemplary aromatic
polyalkenyl coupling agents include polyvinyl benzene, polyvinyl
toluene, polyvinyl xylene, polyvinyl anthracene, polyvinyl
naphthalene, and divinyldurene. Exemplary polyvinyl groups include
divinyl, trivinyl, and tetravinyl groups. In some embodiments,
divinylbenzene (DVB) may be used, and may include o-divinyl
benzene, m-divinyl benzene, p-divinyl benzene, and mixtures
thereof. Exemplary heterocyclic polyalkenyl coupling agents include
divinyl pyridine, and divinyl thiophene. Other exemplary
multifunctional coupling agents include silicon halides,
polyepoxides, polyisocyanates, polyketones, polyanhydrides, and
dicarboxylic acid esters.
[0032] In some embodiments, the pressure sensitive adhesive
compositions of the present disclosure comprise at least about 0.1
parts, in some embodiments, at least about 0.5 parts, at least
about 1 part, or even at least about 2 parts of an acrylic adhesive
composition. In some embodiments, the pressure sensitive adhesive
compositions of the present disclosure comprise no greater than
about 10 parts, in some embodiments, no greater than about 8 parts,
no greater than about 5 parts, or even no greater than about 4
parts an acrylic adhesive composition.
[0033] In some embodiments, the non-tertiary alkyl alcohol contains
4 to 20 carbon atoms. Exemplary acrylic acid esters include
isooctyl acrylate, 2-ethylhexyl acrylate, butyl acrylate, isobornyl
acrylate, and combinations thereof. Exemplary methacrylic acid
esters include the methacrylate analogues of these acrylic acid
esters.
[0034] In some embodiments, the acrylic adhesive composition
comprises the reaction product of at least one acrylic or
methacrylic ester of a non-tertiary alkyl alcohol and, optionally,
at least one copolymerized reinforcing monomer. In some
embodiments, the acrylic adhesive composition comprises at least
about 70 parts, in some embodiments, at least about 80 parts, at
least about 90 parts, at least about 95 parts, or even about 100
parts of at least one acrylic or methacrylic ester of a
non-tertiary alkyl alcohol. In some embodiments, acrylic adhesive
composition comprises no greater than about 30 parts, in some
embodiments, no greater than about 20 parts, no greater than about
10 parts, no greater than about 5 parts, and even no greater than 1
part of at least one copolymerized reinforcing monomer. In some
embodiments, the acrylic adhesive composition does not include a
copolymerized reinforcing monomer.
[0035] In some embodiments, the copolymerized reinforcing monomer
is selected from the group consisting of acrylic acid, methacrylic
acid, 2-carboxyethyl acrylate, N,N' dimethyl acrylamide, N,N'
diethyl acrylamide, butyl carbamoyl ethyl acrylate, and
combinations thereof.
[0036] In some embodiments, the block copolymer adhesive
composition comprises a second block copolymer. In some
embodiments, the second block copolymer may be a linear block
copolymer. A linear block copolymer can be described by the
formula
R-(G).sub.m
wherein R represents a rubbery block, G represents a glassy block,
and m, the number of glassy blocks, is 1 or 2. In some embodiments,
m is one, and the linear block copolymer is a diblock copolymer
comprising one rubbery block and one glassy block. In some
embodiments, m is two, and the linear block copolymer comprises two
glassy endblocks and one rubbery midblock, i.e., the linear block
copolymer is a triblock copolymer.
[0037] In some embodiments, the rubbery block of the second block
copolymer comprises a polymerized conjugated diene, a hydrogenated
derivative thereof, or combinations thereof In some embodiments,
the conjugated dienes comprise 4 to 12 carbon atoms. Exemplary
conjugated dienes useful in the second block copolymer include any
of the exemplary conjugated dienes described above.
[0038] In some embodiments, at least one glassy block, and in some
embodiments, each glassy block of the second block copolymer
comprises a polymerized monovinyl aromatic monomer. In some
embodiments, the monovinyl aromatic monomers comprise 8 to 18
carbon atoms. Exemplary polymerized monovinyl aromatic monomers
useful in the second block copolymer include any of the exemplary
polymerized monovinyl aromatic monomer, as described above.
[0039] In some embodiments, block copolymer adhesive compositions
of the present disclosure comprise a first high Tg tackifier having
a glass transition temperature (Tg) of at least 60 degrees Celsius
(.degree. C.). As used herein, the terms "high glass transition
temperature tackifier" and "high Tg tackifier" refers to a
tackifier having a glass transition temperature of at least
60.degree. C. In some embodiments, the first high Tg tackifier has
a Tg of at least 65.degree. C., or even at least 70.degree. C. In
some embodiments, the first high Tg tackifier has a softening point
of at least about 115.degree. C., and, in some embodiments, at
least about 120.degree. C.
[0040] The first high Tg tackifier is primarily compatible with the
rubbery block of the first block copolymer. In some embodiments,
the first high Tg tackifier is also compatible with the rubbery
block of the second block copolymer. In some embodiments, the first
high Tg tackifier is primarily compatible with the rubbery block of
the first and, optionally, the second block copolymer.
[0041] As used herein, a tackifier is "compatible" with a block if
it is miscible with that block. Generally, the miscibility of a
tackifier with a block can be determined by measuring the effect of
the tackifier on the Tg of that block. If a tackifier is miscible
with a block it will alter (e.g., increase) the Tg of that
block.
[0042] A tackifier is "primarily compatible" with a block if it is
at least miscible with that block, although it may also be miscible
with other blocks. For example, a tackifier that is primarily
compatible with a rubbery block will be miscible with the rubbery
block, but may also be miscible with a glassy block.
[0043] Generally, resins having relatively low solubility
parameters tend to associate with the rubbery blocks; however,
their solubility in the glassy blocks tends to increase as the
molecular weights or softening points of these resins are lowered.
Exemplary tackifiers that are primarily compatible with the rubbery
blocks include polymeric terpenes, hetero-functional terpenes,
coumarone-indene resins, esters of rosin acids, disproportionated
rosin acid esters, hydrogenated rosin acids, C5 aliphatic resins,
C9 hydrogenated aromatic resins, C5/C9 aliphatic/aromatic resins,
dicyclopentadiene resins, hydrogenated hydrocarbon resins arising
from C5/C9 and dicyclopentadiene precursors, hydrogenated styrene
monomer resins, and blends thereof.
[0044] In some embodiments, the block copolymer adhesive
compositions include a second high Tg tackifier that is primarily
compatible with the glassy block(s) of the first block copolymer
and, optionally, with the glassy block(s) of the second block
copolymer. Generally, a tackifier that is primarily compatible with
a glassy block is miscible with the glassy block and may be
miscible with a rubbery block.
[0045] Generally, resins having relatively high solubility
parameters tend to associate with the glassy blocks; however, their
solubility in the rubbery blocks tends to increase as the molecular
weights or softening points of these resins are lowered. Exemplary
tackifiers that are primarily compatible with the glassy blocks
include coumarone-indene resins, rosin acids, esters of rosin
acids, disproportionated rosin acid esters, C9 aromatics,
alpha-methyl styrene, C9/C5 aromatic-modified aliphatic
hydrocarbons, and blends thereof.
[0046] In some embodiments, the pressure sensitive adhesives of the
present disclosure further comprise at least one component selected
from the group consisting of a low Tg tackifier, a plasticizer, and
combinations thereof. As used herein, the term "low glass
transition temperature tackifier" refers to a tackifier having a
glass transition temperature of less than 60.degree. C. Exemplary
low Tg tackifiers include polybutenes.
[0047] Generally, a plasticizer is compatible with one or more
blocks of the linear block copolymer, and/or one or more blocks of
the multi-arm block copolymer. Generally, a plasticizer that is
compatible with a block will be miscible with that block and will
lower the Tg of that block. Exemplary plasticizers include
naphthenic oils, liquid polybutene resins, polyisobutylene resins,
and liquid isoprene polymers.
[0048] In some embodiments, the ratio of multi-arm block copolymers
to linear block copolymers ranges from 1.5:1 to 9:1. In some
embodiments, the ratio of multi-arm block copolymers to linear
block copolymer is at least 1.85:1, or even at least 3:1. In some
embodiments, the ratio of multi-arm block copolymers to linear
block copolymers is no greater than 5.7:1, or even no greater than
4:1.
[0049] In some embodiments, the ratio of the total amount of high
glass transition temperature tackifiers to block copolymers ranges
from 0.8:1 to 1.25:1. In some embodiments, the ratio of the total
amount of high Tg tackifiers to block copolymers is at least
0.85:1, or even at least 0.9:1. In some embodiments, the ratio of
the total amount of high Tg tackifiers to block copolymers is no
greater than 1.15:1, or even no greater that 1.1 to 1.
[0050] In some embodiments, the ratio of the rubbery block
compatible high Tg tackifier to the glassy block compatible high Tg
tackifier is ranges from 1:1 to 9:1. In some embodiments, the ratio
of the rubbery block compatible high Tg tackifier to the glassy
block compatible high Tg tackifier is at least 1.25:1, or even at
least 1.5:1. In some embodiments the ratio of the rubbery block
compatible high Tg tackifier to the glassy block compatible high Tg
tackifier is no greater than 4:1, or even no greater than 3:1.
[0051] In some embodiments, the ratio of the combination of the
block copolymers and high Tg tackifiers to the acrylate component
is at least 8.3:1. In some embodiments, the ratio of the
combination of the block copolymers and high Tg tackifiers to the
acrylate component is at least 12.5:1, at least 22:1, at least
90:1, or even at least 180:1. In some embodiments, the pressure
sensitive adhesive comprises no greater than 10% by weight of the
acrylate component, in some embodiments, no greater than 8%, no
greater than 4%, no greater than 1% or even no greater than 0.5% by
weight.
[0052] In some embodiments, the ratio of the combination of the
block copolymers, high Tg tackifiers, and acrylate component to the
liquid plasticizer ranges from 32:1 to 10:1. In some embodiments,
the ratio of the combination of the block copolymers, high Tg
tackifiers, and acrylate component to the liquid plasticizer is no
great than 25:1, or even no greater than 20:1. In some embodiments,
the ratio of the combination of the block copolymers, high Tg
tackifiers, and acrylate component to the liquid plasticizer is at
least 12.5:1.
[0053] In some embodiments, the pressure sensitive adhesive of the
present disclosure is a hot melt adhesive. As used herein, a hot
melt adhesive is a polymer or blended polymeric material with a
melt viscosity profile such that it can be coated on a substrate or
carrier in a thin layer at a process temperature significantly
above normal room temperature, but retains useful
pressure-sensitive adhesive characteristics at room
temperature.
[0054] The pressure-sensitive adhesive compositions of the present
invention can be made using methods known in the art. For example,
they can be made by dissolving the block copolymers, suitable
tackifiers, any plasticizer(s), and any other additives in a
suitable solvent, and coating onto a substrate (e.g., release
liner, tape backing, core, or panel) using conventional means
(e.g., knife coating, roll coating, gravure coating, rod coating,
curtain coating, spray coating, air knife coating). In some
embodiments, the pressure-sensitive adhesive is prepared in a
substantially solvent-free process (i.e., the adhesive contain no
greater than about 20 wt. % solvent, in some embodiments, no
greater than about 10 wt. % solvent and, in some embodiments, no
greater than about 5 wt. % solvent, in some embodiments, no greater
than 1 wt. % solvent, or even no greater than trace amounts of
solvent (i.e., essentially no solvent). Such substantially
solvent-free processes are known and include, e.g., compounding by
calendaring or roll milling, and extruding (e.g., single. screw,
twin screw, disk screw, reciprocating single screw, pin barrel
single screw, etc.). Commercially available equipment such as
BRABENDER or BANBURY internal mixers are also available to batch
mix the adhesive compositions. After compounding, the adhesive may
be coated through a die into a desired form, such as a layer of
adhesive, or it may be collected for forming at a later time.
[0055] In another aspect, the present disclosure provides a tape
comprising a backing and a pressure sensitive skin adhesive bonded
to at least one major surface of the backing In some embodiments,
the tape comprises a core and a skin adhesive bonded to both major
surfaces of the core, wherein at least one skin adhesive is a
pressure sensitive adhesive. In some embodiments, both skin
adhesives are pressure sensitive adhesives. In some embodiments,
both skin adhesives are the same adhesive. In some embodiments, the
skin adhesives are different adhesives.
[0056] As used herein, the term "core" may be used interchangeably
with the term "backing" when referring to a double-sided tape
construction, i.e., a tape construction having an adhesive layer on
both major surfaces of the backing or core.
[0057] At least one skin adhesive of the tapes of the present
disclosure is a pressure sensitive adhesive comprising a blend of a
block copolymer adhesive composition and an acrylic adhesive
composition, as described herein. In some embodiments, the second
skin adhesive may be a heat-activated adhesive. In some
embodiments, both skin adhesives are pressure sensitive adhesives
comprising a blend of a block copolymer adhesive composition and an
acrylic adhesive composition, as described herein.
[0058] In some embodiments, one or more of the skin adhesive may be
directly bonded to a major surface of a backing or core. In some
embodiments, one or more of the skin adhesives may be indirectly
bonded to a major surface of a backing or core. In some
embodiments, e.g., a primer layer may be interposed between the
skin adhesive and the major surface. Useful primers are generally
known and include, e.g., the primers described in U.S. Pat. No.
5,677,376 (Groves) and U.S. Pat. No. 5,605,964 (Groves).
[0059] Any known backing or core may be used. Exemplary backings
include papers and polymeric films (e.g., polyethylene,
polyurethane, polyester, and polypropylene), metal foils, and woven
and non-woven webs. In some embodiments, a backing or core
comprising a foam may be used, e.g., open cell foams or closed cell
foams. In some embodiments, the foam may comprise thermoplastic
foam. In some embodiments, the foam may comprise a thermoset foam.
Exemplary foams include acrylic foams, polyethylene foams, and
polyurethane foams. Exemplary foams are also described in, e.g.,
the Handbook of Polymer Foams, David Eaves, editor, published by
Shawbury, Shrewsbury, Shropshire, UK: Rapra Technology, 2004.
[0060] Referring to FIG. 1, exemplary tape 10, according to some
embodiments of the present disclosure, comprises backing (or core)
30 and two adhesive layers. First adhesive layer 20 is bonded to
first major surface 31 of backing 30, while second adhesive layer
40 is bonded to second major surface 32 of backing 30. As shown in
FIG. 1, both first adhesive layer 20 and second adhesive layer 40
are directly bonded a major surface of backing 30. In some
embodiments, one or both adhesive layer may be indirectly bonded to
backing 30. For example, in some embodiments, one or more
additional layers (e.g., primers, adhesion promoting layers, films,
webs, scrims, and the like) may be interposed between the backing
and an adhesive layer.
[0061] In another aspect, the present disclosure provides a bonded
composite. As used herein, a bonded composite comprises a first
substrate having a first major surface and a second substrate
having a first major surface, wherein the first major surface of
the first substrate is bonded to the first major surface of the
second substrate via a bonding interface. In the bonded composites
of the present disclosure, the bonding interface comprises a core
having a first skin adhesive bonded to the first major surface of
the core and a second skin adhesive bonded to the second major
surface of the core. At least one skin adhesive of the bonding
interface of the present disclosure is a pressure sensitive
adhesive comprising a blend of a block copolymer adhesive
composition and an acrylic adhesive composition, as described
herein. In some embodiments, both skin adhesives are pressure
sensitive adhesives comprising a blend of a block copolymer
adhesive composition and an acrylic adhesive composition, as
described herein.
[0062] In some embodiments, the first substrate comprises metal,
glass, ceramic, or polymeric materials, and combinations thereof.
In some embodiments, the first substrate includes a primed,
painted, or polymeric surface. In some embodiments, the painted
surface may comprise an automotive paint or clearcoat.
[0063] In some embodiments, the first major surface of the first
substrate is a low surface energy surface. As used herein, a low
surface energy surface means a surface with a measured surface
energy below approximately 35 dyne per centimeter. The surface
energy of a surface may be tested according to ASTM Standard D2578.
Suitable test kits include, e.g., the ACCU-DYNE surface wetability
kit, available from Diversified Enterprises, Claremont, N.H.
[0064] In some embodiments, the second substrate comprises metal,
glass, ceramic, or polymeric materials, and combinations thereof.
In some embodiments, the second substrate includes a primed,
painted, or polymeric surface. In some embodiments, the painted
surface may comprise an automotive paint or clearcoat. In some
embodiments, the first major surface of the second substrate is a
low surface energy surface.
[0065] In some embodiments, the core of the bonding interface
comprises a foam, e.g., an open cell foams or a closed cell foams.
In some embodiments, the foam comprises a thermoplastic foam. In
some embodiments, the foam comprises a thermoset foam. In some
embodiments, the foam comprises an acrylic foam. In some
embodiments, the foam is a flexible foam. Generally, a flexible
foam is a foam which, when in sheet form, can be bent back upon
itself with out fracturing. Exemplary foams are described in, e.g.,
the Handbook of Polymer Foams, David Eaves, editor, published by
Shawbury, Shrewsbury, Shropshire, UK: Rapra Technology, 2004.
[0066] Referring to FIG. 2, exemplary bonded composite 50,
according to some embodiments of the present disclosure, comprises
first substrate 60 bonded to second substrate 70 via bonding
interface 110. Bonding interface 110 comprises a tape comprising
backing (or core) 130 and two adhesive layers. First adhesive layer
120 is bonded to a first major surface of backing 130, while second
adhesive layer 140 is bonded to a second major surface of backing
130. As shown in FIG. 2, both first adhesive layer 120 and second
adhesive layer 140 are directly bonded a major surface of backing
130. In some embodiments, one or both adhesive layer may be
indirectly bonded to backing 130.
[0067] As shown in FIG. 2, in some embodiments, first adhesive
layer 120 is bonded directly to major surface 61 of first substrate
60. Similarly, in some embodiments, second adhesive layer 140 is
directly bonded to major surface 71 of second substrate 70. In some
embodiments, one or both adhesive layers may be indirectly bonded
to a major surface of a substrate. For example, in some
embodiments, one or more additional layers (e.g., primers, adhesion
promoting layers, films, webs, scrims, and the like) may be
interposed between an adhesive layer and a substrate.
[0068] In another aspect, the present disclosure provides methods
of making a tape comprising a backing or a core, wherein the
backing or the core comprises a foam, such as those described
above. The tape comprises at least one skin adhesive, wherein at
least one skin adhesive is a pressure sensitive adhesive comprising
a blend of a block copolymer adhesive composition and an acrylic
adhesive composition, as described herein.
[0069] In some embodiments, the method comprises extruding a foam.
In some embodiments, the method further comprises extruding at
least one skin adhesive. In some embodiments, the foam and at least
one skin adhesive are co-extruded. Methods of extruding polymeric
foams and methods of coextruding polymer foams and skin adhesives
are described, e.g., in U.S. Pat. No. 6,103,152 (Gehlsen et al.)
and U.S. Pat. No. 6,630,531 (Khandpur et al.), both of which are
assigned to the present assignee, and are herein incorporated by
reference in their entireties.
[0070] In some embodiments, the method of making foam core tapes
comprises extruding a foam core and coextruding a first pressure
sensitive adhesive as described herein to form a first adhesive
skin bonded to the first major surface of the foam core. In some
embodiments, the method further comprises extruding a second
adhesive to form a second adhesive skin bonded to the second major
surface of the foam core.
[0071] In some embodiments, the method of making foam core tapes
comprises providing the foam core, which may have been produced by
extrusion or any other known means, and applying a first adhesive
composition comprising a first pressure sensitive adhesive as
described herein to the first surface of the foam core. The first
adhesive composition may be applied by, e.g., laminating or coating
(e.g., knife coating, roll coating, gravure coating, rod coating,
curtain coating, spray coating, or air knife coating).
[0072] In some embodiments, the second adhesive may be
independently extruded or co-extruded with the foam and/or the
first adhesive. In some embodiments, the second adhesive may be
applied to the foam core by, e.g., laminating or coating.
[0073] In some embodiments, the first and/or second adhesive may be
cured. Any known curing processes may be used, e.g., thermal curing
and radiation curing. In some embodiments, one or both adhesives
may crosslinked via exposure to actinic radiation, e.g., electron
beam radiation or ultraviolet radiation.
[0074] The following specific, but non-limiting, examples will
serve to illustrate the invention. In these examples, all
percentages are parts by weight unless otherwise indicated.
TABLE-US-00001 TABLE 1 Summary of materials AA acrylic acid BA
butyl acrylate EA ethyl acrylate IOA isooctyl acrylate 2-EHA
2-ethylhexyl acrylate IRGACURE 651 2,2 dimethoxy-2- Ciba Specialty
Chemicals phenylacetophenone Corp. (Tarrytown, NY) IOTG isooctyl
thioglycolate KRATON 1161-D SIS linear block copolymer Kraton
Polymers, Inc. (15% S, 19% diblock) (Houston, Texas) SANTICIZER 141
2-ethylhexyl diphenyl phosphate Ferro Co. (Bridgeport, New Jersey)
ESCOREZ 1310LC aliphatic C-5 tackifying resin ExxonMobil Chemical
LTD. (Southampton, Hampshire, GB) 4900 CMB Black pigment having a
50/50 MA Hanna Color blend of carbon black in ethylene (Suwanee,
Georgia) vinyl acetate copolymer resin having a melt index of about
150 SUPERESTER stabilized rosin acid ester Arakawa Chemical USA
W-115 (Chicago, IL) IRGANOX 1010 Pentaerythritol tetrakis Ciba
Specialty Chemical (3-(3,5-di-tert-butyl-4- Co. (Tarrytown, NY)
hydroxyphenyl)proprionate TINUVIN 328 2-(2-hydroxy-3,5-di-(tert)-
Ciba Special Chemicals amylphenyl)benzotriazole Co. (Tarrytown, NY)
REGALITE R1125 Hydrogenated hydrocarbon resin Eastman Chemical Co.
(Kingsport, TN) CUMAR 130 Aromatic thermoplastic resin Neville
Chemical Co. (Pittsburgh, PA) NYPLAST 222B Naphthenic oil
plasticizer Nynas Naphthenics AB (Stockholm, Sweden) INDOPOL H-8
Polybutene plasticizer BP Amoco Chemicals (Naperville, IL)
[0075] Preparation of Acrylic Polymers
[0076] Acrylic Polymer 1 (AP-1) was prepared by mixing 45 parts of
IOA; 45 parts of BA; 10 parts of AA; 0.15 part IRGACURE 651; and
0.06 part of IOTG. Discreet film packages were formed from a
packaging film (0.0635 mm thick ethylene vinyl acetate copolymer
film sold as VA-24 Film from CT Film, Dallas, Tex.). The AP-1
composition was sealed into the film packages, which measured
approximately 10 centimeters (cm) by 5 cm by 0.5 cm thick. While
immersed in a water bath maintained between about 21.degree. C. and
about 32.degree. C., the packages were exposed to ultraviolet (UV)
radiation having an intensity of about 3.5 milliWatts per square
centimeter (mW/sq cm), and a total energy of about 1680 milliJoules
per square centimeter (mJ/sq cm) as measured in NIST units. The
method of forming the packages and curing are described in Example
1 of U.S. Pat. No. 5,804,610, the subject matter of which is
incorporated herein by reference in its entirety.
[0077] Acrylic Polymer 2 (AP-2) was prepared according to the
procedure for AP-1, except that 85 parts of 2-EHA; 15 parts of AA;
0.15 parts of IRGACURE 651; and 0.8 part IOTG were used. Similarly,
Acrylic Polymer 3 (AP-3) was prepared according to the procedure
for Acrylic Polymer 1 except that the composition was 95 parts of
2-EHA; 5 parts of AA; 0.15 part IRGACURE 651; and 0.03 part of
IOTG. AP-2 and AP-3 were placed in packages and exposed to UV
energy, according to the procedure for AP-1.
[0078] First Skin Adhesive
[0079] Pressure-sensitive adhesives according to the compositions
shown in Table 2 were compounded using a 60 mm, co-rotating twin
screw extruder (available from Berstorff), (the "first adhesive
extruder"). A polymodal, asymmetric star block copolymer ("PASBC")
was prepared according to U.S. Pat. No. 5,393,373, the subject
matter of which is hereby incorporated by reference in its
entirety. The polymer had number average molecular weights of about
4,000 Dalton and about 21,500 Dalton for the two endblocks,
127,000-147,000 Dalton for the arm, and about 1,100,000 Dalton for
the star measured by SEC (size exclusion chromatography) calibrated
using polystyrene standards. The polystyrene content was between
9.5 and 11.5 percent by weight. The mole percentage of high
molecular weight arms was estimated to be about 30%.
[0080] The polymodal asymmetric block copolymer and a linear
styrene-isoprene-styrene (SIS) block copolymer (KRATON 1161-D) were
dry fed into the first zone of the first adhesive extruder. Using a
roll-feed extruder (available from Berstorff), either acrylic
polymer AP-1 and AP-2 was heated and fed into the third zone of the
first adhesive extruder. Antioxidant (IRGANOX 1010), ultraviolet
light absorber (TINUVIN 328), pigmented EVA (4900 CMB) were dry
fed; and (REGALITE R1125); (CUMAR 130); and (NYPLAST 222B) were
melt fed in to various zones of the first adhesive extruder.
TABLE-US-00002 TABLE 2 First skin adhesive compositions (Weight
Percent). First skin adhesive Adh-1 Adh-2 Adh-3 Adh-4 Adh-5 Adh-6
PASBC* 31.44 30.52 31.16 32.19 30.85 30.85 KRATON 13.47 13.08 13.35
13.80 13.22 13.22 1161D REGALITE 24.92 25.90 26.44 31.90 26.17
26.17 R1125 CUMAR 130 16.62 17.26 17.63 10.64 17.45 17.45 NYPLAST
6.50 6.24 6.37 5.34 0 0 222B INDOPOL H-8 0 0 0 0 6.31 6.31 IRGANOX
1.34 1.31 1.34 1.38 1.32 1.32 1010 TINUVIN 328 1.34 1.31 1.34 1.38
1.32 1.32 4900 CMB 0.38 0.38 0.38 0.37 0.37 0.37 AP-1 4.00 4.00
2.00 0 0 0 AP-2 0 0 0 3.00 3.00 3.00 *Polymodal, asymmetric star
block copolymer
TABLE-US-00003 TABLE 2 Pressure sensitive adhesive compositions
(Weight Percent). First skin adhesive Adh-7 Adh-8 Adh-9 Adh-10
Adh-11 PASBC* 29.59 31.30 31.93 32.23 31.93 Kraton 1161-D 12.62
13.34 13.63 13.77 13.63 REGALITE R1125 29.32 30.85 31.51 31.85
31.51 CUMAR 130 9.77 10.28 10.50 10.61 10.50 NYPLAST 222B 7.90 7.19
7.34 7.42 7.34 INDOPOL H-8 0 0 0 0 0 IRGANOX 1010 1.26 1.32 1.35
1.37 1.35 TINUVIN 328 1.26 1.32 1.35 1.37 1.35 CMB 4900 0.37 0.38
0.38 0.37 0.38 AP-1 0 0 0 0 0 AP-2 7.92 4.00 2.00 1.00 2.00
*Polymodal, asymmetric star block copolymer
[0081] Comparative First Skin Adhesives CE 1-3
[0082] Pressure-sensitive adhesives according to the compositions
shown in Table 3 were compounded in the first adhesive extruder, as
described above for first skin adhesive Adh-1, with the following
exception. These adhesives of these comparative examples did not
contain an acrylic polymer; therefore, no acrylic polymer was fed
in to the second zone of the extruder.
TABLE-US-00004 TABLE 3 Comparative first skin adhesive compositions
(Weight Percent). Comparative first skin adhesive CE-1 CE-2 CE-3
PASBC* 31.80 33.19 31.80 Kraton 1161-D 13.63 14.23 13.63 Regalite
R1125 26.98 32.89 26.98 Cumar 130 17.99 10.97 17.99 Nyplast 222B
6.50 5.50 0 Indopol H-8 0 0 6.50 IRGANOX 1010 1.36 1.42 1.36
TINUVIN 328 1.36 1.42 1.36 CMB 4900 0.38 0.38 0.38 *Polymodal,
asymmetric star block copolymer
[0083] Second Skin Adhesive.
[0084] A pressure sensitive adhesive was compounded in a 60 mm,
co-rotating twin screw extruder (available from Berstorff) (the
"second adhesive extruder") in a similar manner as described for
the first skin adhesives, except that the composition was as
follows: 12.70% of the polymodal, asymmetric star block copolymer
(PASBC); 53.10% (by weight) AP-1; 23.30% tackifying resin (ESCOREZ
1310LC); 3.80% tackifying resin (SUPERESTER W115; 6.20% plasticizer
(SANTICIZER 141); 0.26% antioxidant (IRGANOX 1010); and 0.25%
ultraviolet light absorber (TINUVIN 328).
[0085] Double-Sided Foam Tape Samples.
[0086] Foam cores (FC1-FC-5) having the compositions shown in Table
4 were compounded according to the following procedure. Black
pigmented EVA (4900 CMB) was dry fed in to the first zone of a 90
mm, co-rotating twin screw extruder (the "core extruder")
(available from Berstorff, Hannover, Germany). Using a roll-feed
extruder (available from Berstorff), both acrylic polymers AP-2 and
AP-3 were heated and fed into the second zone of the core extruder.
DUALITE U010-185D expandable microspheres (expandable microspheres
having a shell composition containing acrylonitrile and
methacrylonitrile and a core of isopentane, available from Henkel
Corporation (Gulph Mills, Pa.)) were fed into the ninth zone of the
core extruder.
TABLE-US-00005 TABLE 4 Foam core compositions and properties.
Component Parts By Weight Percent (%) Foam Thick- Composi- Micro-
Density ness tion AP-3 AP-2 spheres Pigment g/cm.sup.3 mm FC-1
91.82 4.8 3 0.38 0.53 0.99 FC-2 90.22 6.6 2.8 0.38 0.55 0.99 FC-3
86.33 9.59 3.7 0.38 0.55 0.98 FC-4 84.73 9.59 5.3 0.38 0.51 0.99
FC-5 94.32 0 5.3 0.38 0.51 0.99
[0087] Three-layer co-extruded tape samples were prepared by
coextruding a first skin adhesive layer, a foam core layer as the
middle layer, and a second skin adhesive layer. Examples 1-11 use
exemplary adhesives according to some embodiments of the present
disclosure (Adh-1 through Adh-11). Reference examples 1-3 use
comparative adhesive CE-1 through CE-3. The tape constructions are
described in Table 5.
[0088] The second skin adhesive was compounded in the second
adhesive extruder, as described above, and fed through an outer
layer of a three-layer, multi-manifold film die obtained from
Cloeren Inc. (Orange, Tex.). A foam core layer was compounded in
the core extruder, as described above, and fed to the center layer
of the three-layer die. A first skin adhesive was compounded in the
first adhesive extruder, as described above, and fed to the outer
layer of the three-layer die, opposite the second skin
adhesive.
[0089] Upon exiting the die, the co-extruded layers were cast onto
a silicone release coated casting roll. The roll was cooled with
water having a temperature of about 12.degree. C. The cooled
extrudate was transferred from the casting roll to a 0.117 mm thick
two-side silicone coated polyethylene release liner that was
transported at the same speed as the casting roll to the end of the
web transport line. The first skin adhesive was in contact with the
liner after the transfer whereas the second skin adhesive was open
to the air. The liner had differential release properties which
allow the tape to be unrolled after winding without liner
confusion. Release liners are well-known in the art, and any known
release liner may be used. Typically, the release liner comprises a
film or paper substrate coated with a release material.
Commercially available release liners include, but are not limited
to, silicone coated papers, and silicone coated films, such as
polyester films. Suitable release liners are also disclosed in U.S.
Pat. Nos. 6,835,422; 6,805,933; 6,780,484; and 6,204,350 assigned
to 3M Innovative Properties Company.
[0090] The foam core and both adhesive skins were crosslinked
on-web using electron beam curing while supported on the liner. Two
sequential irradiation steps acting on opposite faces of the tape
were employed. The first skin adhesive was irradiated through the
polyethylene liner, whereas the second skin adhesive was irradiated
in an open-face condition. The electron beam units were BROADBAND
curtain-type electron beam processors (PCT Engineered Systems,
LLC., Davenport, Iowa), operated according the acceleration voltage
and dose conditions provided in Table 5.
TABLE-US-00006 TABLE 5 Compositions of three-layer tape samples.
First Acrylic First skin adhesive Second skin adhesive skin Polymer
Foam Acceleration Dose Acceleration Dose Ex. adhesive (wt. %) Core
voltage (keV) (Mrad) voltage (keV) (Mrad) 1 Adh-1 4 FC-1 247 11.5
235 10 2 Adh-2 4 FC-2 247 11.5 235 10 3 Adh-3 2 FC-2 247 11.5 235
10 4 Adh-4 3 FC-3 250 10 230 10 5 Adh-5 3 FC-3 250 10 230 10 6
Adh-6 3 FC-3 275 7 230 10 7 Adh-7 7.9 FC-4 250 9 230 10 8 Adh-8 4
FC-4 250 9 230 10 9 Adh-9 2 FC-4 250 9 230 10 10 Adh-10 1 FC-4 250
9 230 10 11 Adh-11 2 FC-5 250 9 230 10 RE-1 CE-1 0 FC-2 247 11.5
235 10 RE-2 CE-2 0 FC-3 245 11.5 230 10 RE-3 CE-3 0 FC-3 245 11.5
230 10
[0091] The cured adhesive tapes were tested for adhesion to low
surface energy automotive paints according to the "Breakaway and
Continuous Peel Adhesion" (BACP), METHOD described in Ford Motor
Co. Specification WSB-M3G138-B. Tensile testing was carried out
using an MTS Model 1122 tensile tester (MTS Systems Corp., Eden
Prairie, Minn.) equipped with TestWorks 4 software programmed to
calculate the breakaway load value, averaged continuous peel value,
and total energy.
[0092] The test surfaces were steel panels painted with automotive
paint systems comprising a base electrocoat, pigmented basecoat,
and a low surface energy, carbamate-crosslinked unpigmented
acrylic-based clearcoat. The experimental tapes were adhered to the
clearcoat for testing. Test Surface 1 had a measured surface energy
(Accu-Dyne solutions) of 33 dynes/cm, and Test Surface 2 had a
measured surface energy of 32 dynes/cm.
[0093] After applying the test tape to the test surface, the
samples were conditioned prior to testing. First, the samples were
conditioned at room temperature for three days. Next, the samples
were conditioned at 38.degree. C. and 100% relative humidity for
six days. Four samples were tested for each tape, and the average
result is reported in Table 6. The observed failure mode(s) for
each set of samples is also reported in Table 6.
TABLE-US-00007 Number Failure mode 1 Foam split 2 Combination of
foam split and clean removal 3 Pop-off
TABLE-US-00008 TABLE 6 Compositions of three-layer tape samples.
First Acrylic Breakaway Peel Total skin Polymer Test Load Peel
Failure Energy Ex. adhesive (wt. %) surface (Newtons) (N/cm) Mode
(N cm) 1 Adh-1 4 1 122.1 48.4 1 764 2 Adh-2 4 1 126.7 51.2 1 803 3
Adh-3 2 1 130.9 49.7 1 787 RE-1 CE-1 0 1 120.4 31.2 1.2 503 4 Adh-4
3 1 99.2 45.7 1 693 5 Adh-5 3 1 109.3 49.0 1 797 6 Adh-6 3 1 98.4
43.4 1 662 RE-2 CE-2 0 1 88.0 18.5 N/A N/A RE-3 CE-3 0 1 75.7 17.5
3 285 7 Adh-7 7.9 1 102.5 51.7 1.3 770 8 Adh-8 4 1 105.1 50.6 1 760
9 Adh-9 2 1 104.4 53.4 1.3 796 10 Adh-10 1 1 103.0 54.1 1 801 11
Adh-11 2 1 93.0 37.8 1 588 12 Adh-1 4 2 126.6 49.1 1 780 13 Adh-2 4
2 131.6 51.4 1 812 14 Adh-3 2 2 127.8 53.2 1 830 RE-4 CE-1 0 2
127.5 50.7 1 796
[0094] Various modifications and alterations of this invention will
become apparent to those skilled in the art without departing from
the scope and spirit of this invention.
* * * * *