U.S. patent application number 11/778757 was filed with the patent office on 2007-11-15 for high refractive index pressure-sensitive adhesives.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Bettie C. Fong, Ying-Yuh Lu, Cheryl L. Moore, DAVID B. OLSON, Todd R. Williams.
Application Number | 20070264517 11/778757 |
Document ID | / |
Family ID | 24423927 |
Filed Date | 2007-11-15 |
United States Patent
Application |
20070264517 |
Kind Code |
A1 |
OLSON; DAVID B. ; et
al. |
November 15, 2007 |
HIGH REFRACTIVE INDEX PRESSURE-SENSITIVE ADHESIVES
Abstract
The present invention provides pressure-sensitive adhesives
having a refractive index of at least 1.48. The pressure-sensitive
adhesives comprise at least one monomer containing a substituted or
an unsubstituted aromatic moiety.
Inventors: |
OLSON; DAVID B.; (Marine on
St. Croix, MN) ; Fong; Bettie C.; (Woodbury, MN)
; Lu; Ying-Yuh; (Woodbury, MN) ; Moore; Cheryl
L.; (Afton, MN) ; Williams; Todd R.; (Lake
Elmo, MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
24423927 |
Appl. No.: |
11/778757 |
Filed: |
July 17, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10701218 |
Nov 4, 2003 |
|
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11778757 |
Jul 17, 2007 |
|
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09605500 |
Jun 28, 2000 |
6663978 |
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10701218 |
Nov 4, 2003 |
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Current U.S.
Class: |
428/523 ;
526/326 |
Current CPC
Class: |
Y10T 428/31938 20150401;
C08F 220/18 20130101; C08F 220/06 20130101; C08F 220/30 20130101;
C09J 7/385 20180101; C08F 220/38 20130101 |
Class at
Publication: |
428/523 ;
526/326 |
International
Class: |
C08F 220/10 20060101
C08F220/10 |
Claims
1. A pressure-sensitive adhesive comprising an aromatic monomer in
an amount of at least 20 parts per 100 parts of total monomer, the
aromatic monomer having the following formula: ##STR6## wherein: Ar
is an aromatic group which is substituted with a substituent
selected from the group consisting of Br.sub.y and (R.sup.3).sub.z
wherein y represents the number of bromine substituents attached to
the aromatic group and is an integer from 0 to 3; R.sup.3 is a
straight or branched alkyl of 2 to 12 carbons; and z represents the
number of R.sup.3 substituents attached to the aromatic ring and is
an integer from 0 to 1, provided that both y and z are not zero
when Ar is substituted; X is oxygen or sulfur; n is 1 to 3; R.sup.1
is an unsubstituted straight or branched alkyl linking group of 6
to 12 carbons; and R.sup.2 is either H or CH.sub.3.
2. The pressure-sensitive adhesive according to claim 1, wherein z
is 1 and R.sup.3 is a straight or branched alkyl of 2 to 8
carbons.
3. The pressure-sensitive adhesive according to claim 1, wherein Ar
is a naphthyl group.
4. The pressure-sensitive adhesive according to claim 1, wherein n
is 1.
5. The pressure-sensitive adhesive according to claim 1, wherein X
is oxygen.
6. The pressure-sensitive adhesive according to claim 1, wherein
the refractive index is at least 1.48.
7. The pressure-sensitive adhesive according to claim 1, wherein
the refractive index is at least 1.50.
8. The pressure-sensitive adhesive according to claim 1, further
comprising: at least one acrylic monomer selected from the group
consisting of monomeric acrylic or methacrylic acid ester of a
non-tertiary alkyl alcohol of about 1 to about 12 carbons.
9. The pressure-sensitive adhesive according to claim 8, wherein
the acrylic monomer is selected from the group consisting of
1-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol,
1-methyl-1-butanol, 1-methyl-1-pentanol, 2-methyl-1-pentanol,
3-methyl-1-pentanol, 2-ethyl-1-butanol, 2-ethyl-1-hexanol,
3,5,5-trimethyl-1-hexanol, 3-heptanol, 2-octanol, 1-decanol,
1-dodecanol, and mixtures thereof.
10. The pressure-sensitive adhesive according to claim 1, further
comprising at least one polar monomer copolymerizable with the
aromatic monomer(s).
12. The pressure-sensitive adhesive according to claim 10, wherein
the polar monomer(s) are selected from the group consisting of
ethylenically unsaturated carboxylic acids, ethylenically
unsaturated sulfonic acids, ethylenically unsaturated phosphoric
acids, acrylamides, N,N-dialkyl substituted acrylamides, N-vinyl
lactams, and N,N-dialkylaminoalkyl acrylates, ethylenically
unsaturated nitriles, and mixtures thereof.
13. The pressure-sensitive adhesive according to claim 10, wherein
the polar monomer(s) are selected from the group consisting of
acrylic acid, methacrylic acid, itaconic acid, acrylamide,
methacrylamide, acrylonitrile, methacrylonitrile, and mixtures
thereof.
14. The pressure-sensitive adhesive according to claim 1, further
comprising: at least one acrylic monomer selected from the group
consisting of monomeric acrylic or methacrylic acid ester of a
non-tertiary alkyl alcohol of about 1 to about 12 carbons, and at
least one polar monomer copolymerizable with the aromatic
monomer(s) and acrylic monomer(s).
15. The pressure-sensitive adhesive according to claim 1, wherein
the aromatic monomer is selected from the group consisting of
6-(4,6-dibromo-2-isopropyl phenoxy)-1-hexyl acrylate and
6-(4,6-dibromo-2-sec-butyl phenoxy)-1-hexyl acrylate.
16. The pressure-sensitive adhesive according to claim 1, further
comprising a crosslinker.
17. The pressure-sensitive adhesive according to claim 1, further
comprising one or more monomers selected from the group consisting
of vinyl esters, vinyl acetate, 2-hydroxyethyl acrylate, styrene,
and mixtures thereof.
18. The pressure-sensitive adhesive according to claim 1, further
comprising a tackifier.
19. The pressure-sensitive adhesive according to claim 1, further
comprising a plasticizer.
20. A pressure-sensitive adhesive having an index of refraction of
at least 1.50 and comprising an aromatic monomer having the
following formula: ##STR7## wherein: Ar is napthyl which is
unsubstituted or substituted with a substituent selected from the
group consisting of Br.sub.y and (R.sup.3).sub.z wherein y
represents the number of bromine substituents attached to the
aromatic group and is an integer from 0 to 3; R.sup.3 is a straight
or branched alkyl of 2 to 12 carbons; and z represents the number
of R.sup.3 substituents attached to the aromatic ring and is an
integer from 0 to 1, provided that both y and z are not zero when
Ar is substituted; X is oxygen or sulfur; n is 1 to 3; R.sup.1 is
an unsubstituted straight or branched alkyl linking group of 2 to
12 carbons; and R.sup.2 is either H or CH.sub.3; copolymerized with
at least one acrylic monomer selected from the group consisting of
monomeric acrylic or methacrylic acid ester of a non-tertiary alkyl
alcohol of about 4 to about 12 carbons and at least one polar
monomer copolymerizable with the aromatic monomer(s) and acrylic
monomer(s).
Description
RELATED APPLICATION DATA
[0001] This application is a continuation of application Ser. No.
10/701,218, filed Nov. 4, 2003, now allowed, which is a divisional
of application Ser. No. 09/605,500 filed Jun. 28, 2000, and issued
as U.S. Pat. No. 6,663,978.
FIELD OF INVENTION
[0002] This invention relates to pressure-sensitive adhesives. More
particularly, this invention relates to pressure-sensitive
adhesives having a high refractive index.
BACKGROUND OF THE INVENTION
[0003] Pressure-sensitive adhesives ("PSAs") are defined herein as
adhesives which exhibit permanent tack at room temperature. This
property allows pressure-sensitive adhesives to adhere tenaciously
upon application with only light finger pressure. PSAs have a
balance of properties: adhesion, cohesion, stretchiness, and
elasticity. Adhesion refers both to immediate adhesion to a surface
and to the bond strength which develops upon application of
pressure (often measured as "peel strength"). Cohesion refers to
the "shear strength" or resistance of the applied PSA to failure
when subjected to shearing forces. Stretchiness refers to the
ability to elongate under low stresses. Elasticity refers to a
property wherein the material exhibits a retractive force when
stretched and retracts when the force is released.
[0004] Pressure-sensitive adhesives have many diverse applications
including applications in optical products. For certain optical
applications, it is useful to match the refractive index (RI) of
the adhesive to that of the substrate to which it is applied. This
matching of refractive index enhances the optical properties of the
construction by reducing glare and reflectance. Glare is defined
herein as the average reflectance over a range of 450-650
nanometers and reflectance is defined herein as the process where a
fraction of the radiant flux incident on a surface is returned into
the same hemisphere whose base is the surface and which contains
the incident radiation (see Handbook of Optics, 2.sup.nd ed.,
McGraw-Hill, Inc., 1995). Often, the substrate is a polymeric
material having refractive indexes in the range of 1.48 to 1.65,
for example, polymethyl(meth)acrylate (PMMA) has a RI of 1.489;
polycarbonate has a RI of 1.585; and polyethylene terephthalate
(PET) has a RI of 1.64.
[0005] Known PSAs have RIs of about 1.47 or less. If these PSAs are
used in optical applications, glare and reflectance may occur.
[0006] Therefore, the need exists for pressure-sensitive adhesives
which have high refractive indexes.
SUMMARY OF THE INVENTION
[0007] The present invention provides pressure-sensitive adhesives
which have a refractive index of at least 1.48. These
pressure-sensitive adhesives are particularly suitable for optical
applications where the substrate similarly has a high refractive
index. The pressure-sensitive adhesives of the present invention
advantageously allow for the matching of refractive index which
reduces glare and reflectance.
[0008] The pressure-sensitive adhesives of the present invention
comprise at least one monomer containing a substituted or an
unsubstituted aromatic moiety.
[0009] One aspect of the present invention is a pressure-sensitive
adhesive comprising the reaction product of: (a) at least one
monomer selected from the group consisting of a monomeric acrylic
or methacrylic acid ester of a non-tertiary alcohol, the alkyl
group of which comprises from about 1 to about 12 carbon atoms,
preferably from about 4 to about 8 carbons; and (b) at least one
monomer containing a substituted or an unsubstituted aromatic
moiety.
[0010] Another aspect of the present invention is a
pressure-sensitive adhesive comprising the reaction product of: (b)
at least one monomer containing a substituted or an unsubstituted
aromatic moiety; and (c) at least one polar monomer copolymerizable
with component (b).
[0011] Yet, another aspect of the present invention is a
pressure-sensitive adhesive comprising the reaction product of: (a)
at least one monomer selected from the group consisting of a
monomeric acrylic or methacrylic acid ester of a non-tertiary
alcohol, the alkyl group of which comprises from about 1 to about
12 carbon atoms, preferably from about 4 to about 8 carbons; (b) at
least one monomer containing a substituted or unsubstituted
aromatic moiety; and (c) at least one polar monomer copolymerizable
with the monomer(s) of components (a) and (b).
[0012] The pressure-sensitive adhesives of the present invention
may optionally comprise other monomers, crosslinkers, and
additives.
[0013] Another embodiment of the present invention is a substrate
coated with the pressure-sensitive adhesives of the present
invention.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0014] The present invention relates to pressure-sensitive
adhesives having a refractive index of at least 1.48. Preferably,
the pressure-sensitive adhesives have a refractive index of at
least 1.50.
[0015] The pressure-sensitive adhesives of the present invention
have a high refractive index and yet have a good balance of the
four properties relevant for pressure-sensitive adhesives:
adhesion, cohesion, stretchiness, and elasticity.
[0016] Refractive index is defined herein as the absolute
refractive index of a material (e.g., a monomer) which is
understood to be the ratio of the speed of electromagnetic
radiation in free space to the speed of the radiation in that
material, with the radiation being of sodium yellow light at a
wavelength of about 583.9 nanometers (nm). The refractive index can
be measured using known methods and is generally measured using an
Abbe Refractometer.
[0017] The pressure-sensitive adhesives of the present invention
are acrylate adhesives comprising at least one aromatic monomer
which is either substituted or unsubstituted. The
pressure-sensitive adhesives may further comprise at least one
acrylic monomer selected from the group consisting of a monomeric
acrylic or methacrylic acid ester of a non-tertiary alcohol and/or
at least one polar monomer. The pressure-sensitive adhesives of the
present invention optionally comprise other monomers which may be
added to improve the properties of the adhesives, such as
crosslinkers, and other additives such as tackifiers or
plasticizers.
Acrylic Monomers
[0018] The acrylic monomers useful in the pressure-sensitive
adhesive of the present invention are typically present at ranges
from about 0 to about 93 parts by weight. Useful acrylic monomers
include at least one monomer selected from the group consisting of
a monomeric acrylic or methacrylic acid ester of a non-tertiary
alkyl alcohol, the alkyl group of which comprises from about 1 to
about 12 carbon atoms, preferably from about 4 to about 8 carbon
atoms, and mixtures thereof.
[0019] Suitable acrylic monomers include, but are not limited to,
those selected from the group consisting of the esters of acrylic
acid or methacrylic acid with non-tertiary alkyl alcohols such as
1-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol,
1-methyl-1-butanol, 1-methyl-1-pentanol, 2-methyl-1-pentanol,
3-methyl-1-pentanol, 2-ethyl-1-butanol, 2-ethyl-1-hexanol,
3,5,5-trimethyl-1-hexanol, 3-heptanol, 2-octanol, 1-decanol,
1-dodecanol, and the like, and mixtures thereof. Such monomeric
acrylic or methacrylic esters are known in the art and are
commercially available.
Aromatic Monomers
[0020] The following aromatic monomers are high refractive index
acrylic monomers, preferably all of which have homopolymer glass
transition temperatures at or below 50.degree. C. These aromatic
monomers, when polymerized alone or in the presence of other
acrylic monomers, result in PSAs having RIs higher than are
otherwise available. By adjusting the ratio of monomers, it is
possible to make PSAs having RIs of at least 1.48.
[0021] The aromatic monomers of the present invention are
represented by the following general Formula (I): ##STR1##
[0022] wherein: [0023] Ar is an aromatic group which is
unsubstituted or substituted with a substituent selected from the
group consisting of Br.sub.y and (R.sup.3).sub.z [0024] wherein y
represents the number of bromine substituents attached to the
aromatic group and is an integer from 0 to 3; [0025] R.sup.3 is a
straight or branched alkyl of 2 to 12 carbons; and [0026] z
represents the number of R.sup.3 substituents attached to the
aromatic ring and is an integer from 0 to 1, [0027] provided that
both y and z are not zero; [0028] X is either oxygen or sulfur;
[0029] n is 0 to 3, preferably n is 0 or 1; [0030] R.sup.1 is an
unsubstituted straight or branched alkyl linking group of 2 to 12
carbons, preferably 2 to 8 carbons; and [0031] R.sup.2 is either H
or CH.sub.3.
[0032] In one embodiment of aromatic monomers, X is oxygen. Within
this embodiment of aromatic monomers, a group of monomers includes
those of Formula (III) wherein Ar is naphthyl: ##STR2## and
R.sup.1, R.sup.2, and n are as defined above. The naphthyl group is
unsubstituted or substituted as described above. Within the group
of naphthyl aromatic monomers, another group is that wherein Ar is
1-napthyl or 2-napthyl.
[0033] Within the embodiment of aromatic monomers where X is
oxygen, another group of monomers includes those of Formula (III)
wherein Ar is phenyl: ##STR3## and R.sup.1, R.sup.2, and n are as
defined above. The phenyl group is unsubstituted or substituted as
described above. Within the substituted group of phenyl aromatic
monomers, preferably the phenyl is dibromo substituted. Within the
bromine substituted group, the phenyl monomers may also be 2-alkyl
substituted or 4-alkyl substituted.
[0034] In an additional embodiment of aromatic monomers, X is
sulfur. Within this embodiment of aromatic monomers, a group of
monomers includes those of Formula (IV) wherein Ar is naphthyl:
##STR4## and R.sup.1, R.sup.2, and n are as defined above. The
naphthyl group is unsubstituted or substituted as described above.
Within the group of naphthyl aromatic monomers, an additional group
is that wherein Ar is 1-napthyl or 2-napthyl.
[0035] Within the embodiment of aromatic monomers where X is
sulfur, another group of monomers includes those of Formula (V)
wherein Ar is phenyl: ##STR5## and R.sup.1, R.sup.2, and n are as
defined above. The phenyl group is unsubstituted or substituted as
described above. Within this group of phenyl aromatic monomers,
preferably the phenyl is dibromo substituted. In another group, the
phenyl monomers may be 2-alkyl substituted or 4-alkyl
substituted.
[0036] Specific examples of aromatic monomers suitable in the
present invention include, but are not limited to,
6-(4,6-dibromo-2-isopropyl phenoxy)-1-hexyl acrylate,
6-(4,6-dibromo-2-sec-butyl phenoxy)-1-hexyl acrylate,
2,6-dibromo-4-nonylphenyl acrylate, 2,6-dibromo-4-dodecyl phenyl
acrylate, 2-(1-naphthyloxy)-1-ethyl acrylate,
2-(2-naphthyloxy)-1-ethyl acrylate, 6-(1-naphthyloxy)-1-hexyl
acrylate, 6-(2-naphthyloxy)-1-hexyl acrylate,
8-(1-naphthyloxy)-1-octyl acrylate, 8-(2-naphthyloxy)-1-octyl
acrylate, 2-phenylthio-1-ethyl acrylate, and phenoxy ethyl
acrylate.
Polar Monomers
[0037] Polar monomers can be used to increase the cohesive strength
of the pressure-sensitive adhesive. Generally, polar monomers are
typically present at ranges from about 0 to about 12 parts by
weight, preferably from about 2 to about 8 parts by weight. Useful
polar monomers include, but are not limited to, those selected from
the group consisting of ethylenically unsaturated carboxylic acids,
ethylenically unsaturated sulfonic acids, and ethylenically
unsaturated phosphoric acids, and mixtures thereof. Examples of
such compounds include, but are not limited to, those selected from
the group consisting of acrylic acid, methacrylic acid, itaconic
acid, fumaric acid, crotonic acid, citraconic acid, maleic acid,
B-carboxyethyl acrylate, sulfoethyl methacrylate, and the like, and
mixtures thereof.
[0038] Other useful copolymerizable polar monomers include, but are
not limited to, acrylamides, N,N-dialkyl substituted acrylamides,
N-vinyl lactams, and N,N-dialkylaminoalkyl acrylates, and mixtures
thereof. Illustrative examples include, but are not limited to,
those selected from the group consisting of N,N-dimethyl
acrylamide, N,N-dimethyl methacrylamide, N,N-diethyl acrylamide,
N,N-diethyl methacrylamide, N,N-dimethylaminoethyl methacrylate,
N,N-dimethylaminopropyl methacrylate, N,N-dimethylaminoethyl
acrylate, N,N-dimethylaminopropyl acrylate, and the like, and
mixtures thereof.
[0039] Preferred polar monomers include acrylic acid, methacrylic
acid, itaconic acid, acrylamide, methacrylamide, acrylonitrile,
methacrylonitrile, and mixtures thereof.
Crosslinkers
[0040] In order to increase the shear or cohesive strength of the
PSAs, a crosslinking additive may be incorporated into the PSA.
[0041] Two main types of crosslinking additives are commonly used.
The first crosslinking additive is a thermal crosslinking additive
such as a multifunctional aziridine. One example is
1,1'-(1,3-phenylene dicarbonyl)-bis-(2-methylaziridine) (CAS No.
7652-64-4), referred to herein as "Bisamide". Such chemical
crosslinkers can be added into solvent-based PSAs after
polymerization and activated by heat during oven drying of the
coated adhesive.
[0042] In another embodiment, chemical crosslinkers which rely upon
free radicals to carry out the crosslinking reaction may be
employed. Reagents such as, for example, peroxides serve as a
source of free radicals. When heated sufficiently, these precursors
will generate free radicals which bring about a crosslinking
reaction of the polymer. A common free radical generating reagent
is benzoyl peroxide. Free radical generators are required only in
small quantities, but generally require higher temperatures to
complete a crosslinking reaction than those required for the
bisamide reagent.
[0043] The second type of chemical crosslinker is a photosensitive
crosslinker which is activated by high intensity ultraviolet (UV)
light. Two common photosensitive crosslinkers used for hot melt
acrylic PSAs are benzophenone and copolymerizable aromatic ketone
monomers as described in U.S. Pat. No. 4,737,559. Another
photocrosslinker, which can be post-added to the solution polymer
and activated by UV light is a triazine, for example,
2,4-bis(trichloromethyl)-6-(4-methoxy-pheynl)-s-triazine. These
crosslinkers are activated by UV light generated from artificial
sources such as medium pressure mercury lamps or a UV
blacklight.
[0044] Hydrolyzable, free-radically copolymerizable crosslinkers,
such as monoethylenically unsaturated mono-, di-, and trialkoxy
silane compounds including, but not limited to,
methacryloxypropyltrimethoxysilane (available from Gelest, Inc.,
Tullytown, Pa.), vinyldimethylethoxysilane,
vinylmethyldiethoxysilane, vinyltriethoxysilane,
vinyltrimethoxysilane, vinyltriphenoxysilane, and the like, are
also useful crosslinking agents.
[0045] Multi-functional acrylates are useful for bulk or emulsion
polymerization. Examples of useful multi-functional acrylate
crosslinking agents include, but are not limited to, diacrylates,
triacrylates, and tetraacrylates, such as 1,6-hexanediol
diacrylate, poly(ethylene glycol) diacrylates, polybutadiene
diacrylate, polyurethane diacrylates, and propoxylated glycerin
triacrylate, and mixtures thereof.
[0046] Crosslinker is typically present from 0 to about 1 part by
weight based on 100 parts by weight adhesive solids.
[0047] Crosslinking may also be achieved using high energy
electromagnetic radiation such as gamma or e-beam radiation. In
this case, no crosslinker may be required.
Chain Transfer Agent
[0048] The present invention may optionally further comprise a
chain transfer agent. Examples of useful chain transfer agents
include, but are not limited to, those selected from the group
consisting of carbon tetrabromide, mercaptans, alcohols, and
mixtures thereof.
Other Monomers
[0049] Other monomers may be added to improve performance, reduce
cost, etc. in quantities which do not render the pressure-sensitive
adhesive non-tacky. Examples of such other monomers include vinyl
esters, vinyl acetate, 2-hydroxyethyl acrylate, styrene, and the
like.
Additives
[0050] Following copolymerization, other additives may be blended
with the resultant acrylate or methacrylate copolymer. For example,
compatible tackifiers and/or plasticizers may be added to aid in
optimizing the ultimate tack and peel properties of the PSA. The
use of such tack-modifiers is common in the art, as is described in
the Handbook of Pressure-Sensitive Adhesive Technology, edited by
Donatas Satas (1982). Examples of useful tackifiers include, but
are not limited to, rosin, rosin derivatives, polyterpene resins,
coumarone-indene resins, and the like. Plasticizers which may be
added to the adhesive of the invention may be selected from a wide
variety of commercially available materials. In each case, the
added plasticizer must be compatible with the PSA. Representative
plasticizers include polyoxyethylene aryl ether, dialkyl adipate,
2-ethylhexyl diphenyl phosphate, t-butylphenyl diphenyl phosphate,
di(2-ethylhexyl) adipate, toluenesulfonamide, dipropylene glycol
dibenzoate, polyethylene glycol dibenzoate, polyoxypropylene aryl
ether, dibutoxyethoxyethyl formal, and dibutoxyethoxyethyl adipate.
When used, tackifiers are preferably added in an amount not to
exceed about 150 parts by weight per 100 parts by weight copolymer,
and plasticizer may be added in an amount up to about 50 parts by
weight per 100 parts by weight copolymer.
Polymerization Methods
[0051] Adhesives useful in this invention can be polymerized by
conventional free-radical polymerization methods. Suitable methods
of polymerization include solution polymerization, suspension
polymerization, emulsion polymerization, and bulk
polymerization.
Substrates
[0052] The PSAs of the present invention may be coated upon a
variety of flexible and inflexible backing materials using
conventional coating techniques to produce PSA-coated sheet
materials. Flexible substrates are defined herein as any material
which is conventionally utilized as a tape backing or may be of any
other flexible material. Examples include, but are not limited to,
paper, plastic films such as polypropylene, polyethylene, polyvinyl
chloride, polyester (polyethylene terephthalate), polycarbonate,
polymethyl(meth)acrylate (PMMA), cellulose acetate, cellulose
triacetate, and ethyl cellulose. Additionally, flexible substrates
include, but are not limited to, woven fabric formed of threads of
synthetic or natural materials such as cotton, nylon, rayon, glass,
or ceramic material, or they may be nonwoven fabric such as
air-laid webs or natural or synthetic fibers or blends of these.
Examples of inflexible substrates include, but are not limited to,
metal, metallized polymeric film, or ceramic sheet material. The
PSA-coated sheet materials may take the form of any article
conventionally known to be utilized with PSA compositions such as
labels, tapes, signs, covers, marking indices, and the like.
Method of Application
[0053] The PSAs of the present invention may be coated using a
variety of conventional coating techniques such as roll coating,
knife coating, or curtain coating. The PSAs may also be coated
without modification by extrusion, coextrusion, or hot melt
techniques by employing suitable conventional coating devices.
Primers may be used, but they are not always necessary. The
resultant coatings do not require curing or crosslinking. However,
if enhancement of resistance to solvents, etc., is desired,
crosslinking may be effected by standard methods well-known in the
art, such as radiation curing (electron beam or ultraviolet light)
or chemical crosslinking.
EXAMPLES
[0054] The present invention will be further described with
reference to the following non-limiting examples and test methods.
All parts, percentages, and ratios are by weight unless otherwise
specified. TABLE-US-00001 TABLE OF COMPONENTS Abbreviation Name
Available From BA n-butyl acrylate BASF Corporation, Parsippany, NJ
AA acrylic acid BASF Corporation, Parsippany, NJ PEA phenoxy ethyl
acrylate Sartomer Co., West Chester, PA IOA iso-octyl acrylate CPS
Chemical Co., Old Bridge, NJ IRGACURE .TM. 651 2,2-dimethoxy-1,2-
Ceiba-Geigy, Hawthorne, diphenylethan-1-one NY TPO (Lucirin TPO)
diphenyl (2,4,6-trimethylbenzoyl) BASF Corporation, phosphine oxide
Charlotte, NC EB 9220 hexafunctional aromatic urethane UCB
Chemicals Corp., acrylate Smyrna, GA 2-isopropylphenol and 2-sec-
Schenectedy International, butylphenol Schenectedy, NY bromine
Aldrich Chemical ethyl acetate Company Inc, Milwaukee, aqueous
sodium hydrosulfite WI aqueous sodium carbonate sodium iodide
6-chlorohexanol t-butyl methyl ether HCl 6-iodohexanol Toluene
Hydroquinone p-toluene sulfonic acid 4-nonylphenol Phenothiazine
1-naphthol ethylene carbonate Triethylamine acryloyl chloride
para-toluene sulfonic acid 4-methoxyphenol or methyl hydoquinone
2-(phenylthio)ethanol NPAL tris(N-nitroso-N-phenylhydroxyl
ChemFirst Fine Chemicals, amine) aluminum salt Pascagoula, MS VAZO
.TM. 67 2,2'-azobis(2-methylbutanenitrile) E.I. Du Pont De Nemours
and Company, Wilmington, DE N,N'-bis-1,2- Xian Modern Chemistry
propyleneisophthalamide Research Institute of China, Xi'an, China
RHODOCAL DS-10 .TM. Sodium dodecylbenzene sulfonate Rhone-Poulenc
North American Chem., Cranbury, NJ K.sub.2S.sub.2O.sub.8 J.T. Baker
Co., Phillipsburg, NJ
Test Methods
[0055] The test methods used to evaluate the PSA coated flexible
sheet materials of the examples are industry standard tests. The
standard tests are described in various publications of the
American Society for Testing and Materials (ASTM), Philadelphia,
Pa., and the Pressure Sensitive Tape Council (PSTC).
Shear Strength (ASTM: D3654-78; PSTC-7)
[0056] The shear strength is a measure of the cohesiveness or
internal strength of an adhesive. It is based upon the amount of
force required to pull an adhesive strip from a standard flat
surface in a direction parallel to the surface to which it has been
affixed with a definite pressure. It is measured in terms of time
(in minutes) required to pull a standard area of adhesive coated
sheet material from a stainless steel test panel under stress of a
constant, standard load.
[0057] The tests were conducted on adhesive-coated strips applied
to a stainless steel panel such that a 12.7 mm by 12.7 mm portion
of each strip was in firm contact with the panel with one end
portion of the tape being free. The panel with coated strip
attached was held in a rack such that the panel forms an angle of
178.degree. with the extended tape free end which is then tensioned
by application of a force of one kilogram applied as a hanging
weight from the free end of the coated strip. The 2.degree. less
than 180.degree. is used to negate any peel forces, thus insuring
that only the shear forces are measured, in an attempt to more
accurately determine the holding power of the tape being tested.
The time elapsed for each tape example to separate from the test
panel is recorded as the shear strength. Unless otherwise noted,
all shear failures reported herein are cohesive failures of the
adhesive.
Peel Adhesion (ASTM D3330-78 PSTC-1 (11/75))
[0058] Peel adhesion is the force required to remove a coated
flexible sheet material from a test panel measured at a specific
angle and rate of removal. In the examples, this force is expressed
in Newtons per 100 mm (N/100 mm) width of coated sheet. The
procedure followed is:
[0059] 1. A 12.7 mm width of the coated sheet is applied to the
horizontal surface of a clean glass test plate with at least 12.7
lineal cm in firm contact. A 2 kg hard rubber roller is used to
apply the strip.
[0060] 2. The free end of the coated strip is doubled back nearly
touching itself so the angle of removal will be 180.degree.. The
free end is attached to the adhesion tester scale.
[0061] 3. The glass test plate is clamped in the jaws of a tensile
testing machine which is capable of moving the plate away from the
scale at a constant rate of 2.3 meters per minute.
[0062] 4. The scale reading in Newtons is recorded as the tape is
peeled from the glass surface. The data is reported as the average
of the range of numbers observed during the test.
Measurement of Refractive Index
[0063] The refractive index of the pressure-sensitive adhesives and
cured films were measured using an Abbe Refractometer, Made by Erma
Inc., of Tokyo, Japan and distributed by Fisher Scientific.
Monomer Preparation
1. Synthesis of 6-(4,6-dibromo-2-isopropylphenoxy)-1-hexyl acrylate
(DBiPPHA)
[0064] In a 12 liter round bottom flask equipped with a mechanical
stirrer, condenser, nitrogen cap, addition funnel and temperature
probe, 1400 grams of 2-isopropylphenol was mixed with 4630 grams of
deionized water. The mixture was stirred with a mechanical mixer
and purged with nitrogen for about 10 minutes. 3417 grams bromine
was added to the mixture drop-wise through the addition funnel. The
temperature was maintained at about 30.degree. C. or less using an
ice bath. Following addition of the bromine, the reaction mixture
was stirred for 1 hour at room temperature. Reaction completion was
determined by gas chromatography, by monitoring the disappearance
of the starting material, 2-isopropylphenol, and of monobrominated
species.
[0065] Upon completion of the reaction, 4075 grams of ethyl acetate
was added. The mixture was stirred for 15 minutes and then allowed
to phase split. The bottom (aqueous) layer was removed and 2765
grams of a 13 wt. % aqueous sodium hydrosulfite solution was added.
The mixture was stirred well and then allowed to phase split. The
bottom (aqueous) layer was removed and 2842 grams of a 15 wt. %
aqueous sodium carbonate solution was added. The mixture was
stirred well and then allowed to phase split. The bottom (aqueous)
layer was removed and solvent was stripped from the top layer using
a rotary evaporator. This procedure provided approximately 2556
grams of 4,6-dibromo-2-isopropyl phenol (DBiPP).
[0066] A 12 liter, four neck, round bottom flask was set up with a
mechanical stirrer, condenser, temperature probe and addition
funnel in a cooling bath. 800 grams of 4,6-dibromo-2-isopropyl
phenol (DBiPP) was added to the flask along with 4902 grams of
deionized water and 408 grams of sodium iodide. Using the addition
funnel, 435 grams of a 50% sodium hydroxide solution was added
while maintaining the temperature below 25.degree. C. The cooling
bath was then removed and the reaction mixture was heated to reflux
(100.degree. C.). Using a clean addition funnel, 744 grams of
6-chlorohexanol was added over 1 hour and 30 minutes. The reaction
was mixed 2 more hours at which point gas chromatography (GC)
analysis indicated 0.3% of the starting DBiPP remained unreacted.
The solution was cooled and left at room temperature (22-25.degree.
C.) overnight.
[0067] 4196 grams of ethyl acetate was added to the reaction flask
and mixed for 10 minutes (t-butyl methyl ether or other suitable
organic solvent may be used). The mixture was allowed to phase
split. The bottom aqueous layer was removed by vacuum and the pH
was recorded at 11. The washing step was repeated a second time
using a solution of 27 grams of 37% HCl in 980 grams of deionized
water. The aqueous phase that was removed had a pH of 1. The
washing step was repeated a third time using 980 grams of a 3%
(w/w) aqueous sodium carbonate solution. Again, the aqueous phase
was removed and the pH was recorded at 11. The final washing was
done with a 4.7% (w/w) aqueous solution of sodium chloride (982
grams). The aqueous phase was again removed by vacuum. The organic
phase filtered and concentrated on a rotary evaporator using a
water aspirator. Residual solvent was removed using a vacuum pump
while stirring the concentrate with a magnetic stirrer. 1250 grams
of a yellow liquid was obtained. The yellow liquid was purified by
continuous distillation using a rolled film evaporator. First,
6-chlorohexanol and 6-iodohexanol were removed at the following
conditions: 130.degree. C. oil bath and 5-20 microns Hg vacuum. The
residue was then continuously distilled on the rolled film
evaporator using the following conditions: 130.degree. C. oil bath
and 1 micron Hg vacuum. 832 grams of the water white alkylated
product {6-(4,6-dibromo-2-isopropyl phenoxy)-1-hexanol} was
recovered. It can be noted here that optionally, a wiped film
evaporator can be used in place of the rolled film evaporator.
[0068] A 5 liter, four neck round bottom flask was equipped with a
mechanical stirrer, Dean Stark trap, condenser, and temperature
probe. The flask was charged with 600 grams of
6-(4,6-dibromo-2-isopropyl phenoxy)-1-hexanol; 2805 grams of
toluene; 200 ppm each of methyl hydroquinone and hydroquinone; 15.2
grams p-toluene sulfonic acid and 131 grams acrylic acid. This
mixture was heated to reflux with stirring to azeotrope the water.
After 6 hours of refluxing, 30 ml of water had been removed and
99.2% of the 6-(4,6-dibromo-2-iso-propyl phenoxy)-1-hexanol had
been converted to 6-(4,6-dibromo-2-iso-propyl phenoxy)-1-hexyl
acrylate based on GC analysis. The solution was then cooled and
allowed to mix overnight.
[0069] 828 grams of a 0.27% HCl solution was added to the reaction
flask and mixed for 5 minutes. The mixture was allowed to phase
split and the aqueous bottom phase (pH=1) was removed by vacuum.
The washing was repeated by adding 903 grams of an 8.9% (w/w)
aqueous solution of sodium carbonate. The aqueous phase was removed
after phase separation. A third wash was done using 867 grams of a
5.1% (w/w) aqueous sodium chloride solution. The aqueous phase was
again removed by vacuum. The organic phase was filtered and
concentrated on a rotary evaporator using a water aspirator.
Residual solvent was removed using a vacuum pump while stirring the
concentrate with a magnetic stirrer. 650 grams of a hazy, light
yellow liquid was obtained. The yellow liquid was then purified by
continuous distillation in a rolled film evaporator using the
following conditions: 175.degree. C. oil bath and 1 micron Hg
vacuum to give the water white product. NMR analysis indicated a
98.8% purity prior to distillation and a purity of >99% in the
distilled product, 6-(4,6-dibromo-2-iso-propyl phenoxy)-1-hexyl
acrylate (DBiPPHA).
2. Synthesis of 6-(4,6-dibromo-2-sec-butylphenoxy)-1-hexyl acrylate
(DBsBPHA)
[0070] The analogous monomer 6-(4,6-dibromo-2-sec-butyl
phenoxy)-1-hexyl acrylate (DBsBPHA) was prepared in the same manner
starting with a stoichiometric equivalent amount of 2-sec-butyl
phenol rather than the 2-isopropylphenol.
3. Synthesis of 2,6-dibromo-4-nonylphenyl acrylate (DBpNPA)
[0071] 44 grams (0.2 mole) 4-nonylphenol was mixed in a three neck
round bottom flask with 180 grams deionized water. The mixture was
stirred with a mechanical stirrer. The reaction solution was purged
well with nitrogen. To the flask, 66 grams (0.41 mole) bromine was
added dropwise, keeping the reaction temperature about 30.degree.
C. After completing the addition, the reaction was stirred for 1/2
hour at room temperature. The reaction progress was monitored using
GC. Because the phenol was a mixture of isomers, an additional 11
grams of bromine was added to react all the starting material.
[0072] 160 grams ethyl acetate was added with stirring and the
mixture was allowed to phase split. The bottom (aqueous) layer was
removed. The organic layer was washed sequentially with a pre-mix
of 3.5 grams sodium hydrosulfite in 23 grams water and a pre-mix of
3.9 grams sodium chloride in 26 grams water. For each washing, the
aqueous premix was stirred well with the organic layer, allowed to
phase split and then removed. After the final washing, the solvent
was stripped on a rotary evaporator to give a yellow oil.
[0073] The yellow oil was distilled using a distillation head and
short vigeraux column. The product was distilled at 1.0 mm Hg and a
head temperature of 165-170.degree. C. The yield is 66 grams (87%)
of light yellow liquid. Analysis by GC and NMR verified the
material to be 2,6-dibromo-4-nonylphenol.
[0074] 30.5 grams (0.08 mole) 2,6-dibromo-4-nonylphenol, 64 grams
t-butyl methyl ether, 9.8 grams (0.096 mole) triethyl amine, and
0.005 grams phenothiazine were mixed in a three neck round bottom
flask equipped with a mechanical stirrer, temperature probe, and
addition funnel. 8.4 grams (0.092 mole) acryloyl chloride was added
dropwise. An ice water bath was used to keep the reaction
temperature below 20.degree. C. GC shows complete reaction
conversion.
[0075] 45.6 grams deionized water was added, the mixture stirred
and allowed to phase split. The lower aqueous phase was removed.
The organic layer was washed sequentially with a pre-mix of 0.2
grams concentrated HCl in 8.7 grams deionized water; a pre-mix of
1.7 grams sodium carbonate in 9 grams deionized water; and a
pre-mix of 0.8 gram NaCl in 9 grams deionized water. The aqueous
pre-mixes were mixed with the organic phase, allowed to phase
split, and then discarded. The organic solution was then dried with
magnesium sulfate, filtered, and the solvent removed using a rotary
evaporator. This method produced 32 grams (92%) of a light yellow
oil which was characterized by NMR and GC analysis.
4. Synthesis of 2,6-dibromo-4-dodecylphenyl acrylate (DBpDDPA)
[0076] The reactions were run as outlined above, except a
stoichiometric equivalent of 4-dodecylphenol was used instead of
4-nonylphenol.
5. Synthesis of 2-(1-naphthyloxy)-1-ethyl acrylate (1-NOEA)
[0077] A 5 liter, three neck round bottom flask was equipped with a
temperature probe, mechanical stirrer, and condenser. 400 grams
1-naphthol, 269 grams ethylene carbonate and 281 grams
triethylamine were added to the flask. Using medium agitation, the
batch was heated to 95.degree. C. and began to give off CO.sub.2.
The batch was held at this temperature for 12 hours, a sample was
taken and residual 1-naphthol was determined by GC. Heating of the
batch continued at 95.degree. C. until there was less than 3%
residual 1-naphthol.
[0078] The reaction was then cooled to room temperature and 1470
grams tert-butyl methyl ether and 56 grams triethylamine were
added. 0.15 gram hydroquinone and 0.15 gram hydroquinone monomethyl
ether were added as inhibitors. To the well-stirred reaction, 289
grams acryloyl chloride was added over a 2-4 hour period, keeping
the batch temperature between 25-30.degree. C. The batch was
stirred with medium agitation at room temperature for 1 hour after
completing the addition. A sample was taken and GC run to determine
reaction completion (<1% residual
2-(1-naphthyloxy)-1-ethanol).
[0079] The batch was then cooled to room temperature and then
washed, first with 400 grams deionized water and 11 grams HCl, then
with 250 grams of 15% sodium carbonate in water solution, and then
with 250 grams of 20% sodium chloride solution. Residual solvent
was removed using a rotary evaporator. The product was a dark
colored, low viscosity (<80 cps) liquid (570 grams).
[0080] The crude monomer was purified using a continuous a high
vacuum rolled film evaporator (available from UIC Inc. of Joliet,
Ill.) with the following conditions: 110.degree. C. jacket
temperature, 30.degree. C. condenser temperature, 40.degree. C.
feed temperature, 300 rpm rotor speed, and 1 micron vacuum. The
distillation gave an 80-85% product split. The product, 1-NOEA (475
grams), was a light yellow to orange liquid and was characterized
by .sup.13C NMR and confirmed to be 95% pure.
6. Synthesis of 6-(1-naphthyloxy)-1-hexyl acrylate (1-NOHA)
[0081] A 1 liter, three neck flask was equipped with a mechanical
stirrer, temperature probe, and a condenser. The following reagents
were added: 50 grams 1-naphthol, 312 grams deionized water, 5.2
grams sodium iodide, and 55.4 grams sodium hydroxide (50% solution
in water). The mixture was heated to reflux. To the refluxing
reaction, 94.7 grams 6-chloro-1-hexanol was added dropwise through
an addition funnel over a 2-hour period. Heating at reflux was
continued for an additional hour after completing the addition. GC
analysis showed <1% residual starting material.
[0082] The reaction was cooled to room temperature. 366 grams
t-butyl methyl ether was added. The reaction mixture was stirred,
then poured into a separatory funnel, and allowed to phase split.
The aqueous phase was removed and the organic phase washed with 6.9
grams concentrated HCl in 125 grams deionized water, then with 6.1
grams NaCl in 125 grams deionized water. The remaining solvent was
stripped from the product using a rotary evaporator.
[0083] The product was distilled at a pot temperature of
220-260.degree. C., head temperature of 200-230.degree. C., at
0.1-0.2 mm Hg. This procedure yielded 63.5 grams of a light brown,
somewhat viscous liquid. GC showed it was >98% pure
6-(1-naphthyloxy)-1-hexanol. This material was used in the next
step of the synthesis.
[0084] A 1 liter, three neck flask, equipped with a mechanical
stirrer, temperature probe, and Dean-Stark trap with condenser was
charged with the following reagents: 60 grams
6-(1-naphthyloxy)-1-hexanol, 226 grams toluene, 2.5 grams
para-toluene sulfonic acid, 21.2 grams acrylic acid, 0.027 gram
hydroquinone, and 0.03 gram 4-methoxyphenol. The mixture was heated
to reflux, collecting the water which evolved in the Dean-Stark
trap. After 3 hours, thin layer chromatography showed the reaction
is complete (i.e., no starting material remained).
[0085] The reaction was cooled to room temperature and 132 grams of
deionized water were added. The mixture was put into a separatory
funnel, shaken and allowed to phase split. The aqueous layer was
removed and the organic phase was washed with 0.3 gram concentrated
HCl in 44 grams deionized water, then with 1.3 grams sodium
carbonate in 44 grams deionized water, then with 1.4 grams sodium
chloride in 44 grams deionized water. The remaining solvent was
stripped using a rotary evaporator. The crude product residue was
passed through a flash silica gel column eluting with 5% ethyl
acetate/95% heptanes. The product fractions were collected and the
solvent stripped using a rotary evaporator. The light greenish oil
product crystallized on standing to give 45 grams of off-white
crystals with a melting point of 37-39.degree. C. GC and .sup.13C
NMR analysis confirmed the product to be 99% pure
6-(1-naphthyloxy)-1-hexyl acrylate (1-NOHA).
7. Synthesis of 2-phenylthio ethyl acrylate (PTEA)
[0086] A 500 ml three neck round bottom flask equipped with a
stirrer, vigeraux column and distillation head/receiver was charged
with 50 grams (0.32 mole) of 2-(phenylthio) ethanol, 139.5 grams
(1.62 mole) methylacrylate, 0.22 gram dibutyltin diacetate, 0.015
gram NPAL and 0.015 gram 4-methoxyphenol. The reaction flask was
heated to 100.degree. C. to distill off an azeotrope of methanol
and methylacrylate. As the distillation subsided, 150 grams of
methylacrylate was added to the flask. This addition procedure was
repeated two more times.
[0087] Gas chromatographic analysis of the reaction mixture showed
<1% unreacted 2-(phenylthio)ethanol. The reaction mixture was
then cooled to 50.degree. C. and the residual methylacrylate was
removed by vacuum distillation. The product, 2-phenylthio ethyl
acrylate (50 grams), was a yellow liquid and was characterized by
.sup.13C NMR to be 97% pure.
Preparation of PSAs
[0088] The PSAs of the present invention can be made by solution,
emulsion or bulk polymerization methods. The procedures for these
polymerization methods are described below as Method A, Method B,
and Method C, respectively.
Method A--Solution Polymerization
[0089] Comparative Example C-1 and Examples 1-14 were prepared
using a solution polymerization method. All components were weighed
into a glass bottle having a 120 gram capacity. The contents of the
bottles were deoxygenated by purging with nitrogen at a flow rate
of 1 liter per minute for 35 seconds. The bottles were sealed and
placed in a rotating water bath at 57.degree. C. for 24 hours to
effect essentially complete polymerization. The polymer solutions
were coated onto a 37 micrometer (1.5 mil) polyester film to
provide a dry coating thickness of 25 micrometers (.about.1 mil).
The coated film was equilibrated and thereafter tested under
conditions of about 23.degree. C. and 50% relative humidity as
described by the shear and adhesion test methods. Equilibrated
films were utilized to measure refractive index.
Method B--Emulsion Polymerization
[0090] Examples 15 and 16 were prepared using an emulsion
polymerization method (Method B). All components were added to a
500 ml beaker and mixed until the aqueous and organic phases were
homogeneous. The mixture was then homogenized in a Waring Blender
for 2 minutes to prepare emulsions for polymerization. The
emulsions were placed in glass bottles having a 120 gram capacity.
The contents of the bottles were deoxygenated by purging with
nitrogen at a flow rate of 1 liter per minute for about 2 minutes.
The bottles were sealed and placed in a rotating water bath at
60.degree. C. for 24 hours to effect essentially complete
polymerization. After polymerization, the latexes were filtered
through cheesecloth to remove coagulum before coating and
evaluation. The polymer latexes were coated onto a 37 micrometer
(1.5 mil) polyester film to provide a dry coating thickness of
about 25 micrometers (.about.1 mil). The coated films were
equilibrated and thereafter tested under conditions of about
23.degree. C. and 50% relative humidity as described by the shear
and adhesion test methods. Equilibrated films were utilized to
measure refractive index.
Method C--Bulk Polymerization
[0091] Examples 17-29 and Comparative Example C-2 were prepared
using a bulk polymerization method (Method C). The monomer
components were mixed in 250 ml glass bottles to which was added
CBr.sub.4 (0.2% of total monomer weight) and IRGACURE.TM. 651 (0.1%
of total monomer weight). The contents of the bottles were
thoroughly mixed and deoxygenated by purging with nitrogen at a
flow rate of 1 liter per minute for 2 minutes. Using a knife
coater, the mixtures were coated to a thickness of about 50-80
micrometers (.about.2-3 mils) between a primed 38 micrometer (1.5
mil) polyester film and a release liner. The resulting coatings
were polymerized using ultraviolet radiation under a fluorescent
black light (about 680 millijoules/cm.sup.2) for about 10 minutes.
The coated film was equilibrated and thereafter tested under
conditions of about 23.degree. C. and 50% relative humidity as
described by the shear and adhesion test methods. Equilibrated
films were utilized to measure refractive index as noted above.
Comparative Example C-1 (BA/AA 92.5/7.5)
[0092] 16.65 grams butyl acrylate, 1.35 grams acrylic acid, 42
grams acetone, and 0.036 grams VAZO.TM. 67 free radical initiator
were charged into a glass bottle and polymerized as described in
Method A. Measured % solids was 28.0%. Refractive index, shear, and
adhesion results are given in Table II.
Example 1 (BA/AA/1-NOHA 72.5/7.5/20)
[0093] 13.05 grams butyl acrylate, 3.6 grams 1-NOHA, 1.35 grams
acrylic acid, 42 grams acetone, and 0.036 grams VAZO.TM. 67 free
radical initiator were charged into a glass bottle and polymerized
as described in Method A. Measured % solids were 26.9%. Refractive
index, shear, and adhesion results are given in Table II.
Example 2 (BA/AA/1-NOHA 52.5/7.5/40)
[0094] 9.45 grams butyl acrylate, 7.2 grams 1-NOHA, 1.35 grams
acrylic acid, 42 grams acetone, and 0.036 grams VAZO.TM. 67 free
radical initiator were charged into a glass bottle and polymerized
as described according to Method A. Measured % solids was 26.4%.
Refractive index, shear, and adhesion results are given in Table
II.
Example 3 (BA/AA/1-NOEA 72.5/7.5/20)
[0095] 13.05 grams butyl acrylate, 3.6 grams 1-NOEA, 1.35 grams
acrylic acid, 42 grams acetone, and 0.036 grams VAZO.TM. 67 free
radical initiator were charged into glass bottle and polymerized as
described in Method A. Measured % solids were 28.29%. Refractive
index, shear, and adhesion results are given in Table II.
Example 4 (BA/AA/1-NOEA 52.5/7.5/40)
[0096] 9.45 grams butyl acrylate, 7.2 grams 1-NOEA, 1.35 grams
acrylic acid, 42 grams acetone, and 0.036 grams VAZO.TM. 67 free
radical initiator were charged into a glass bottle and polymerized
as described in Method A. Measured % solids was 29.8%. Refractive
index, shear, and adhesion results are given in Table II.
Example 5 (BA/AA/1-NOEA 85.5/7.5/7)
[0097] 15.39 grams butyl acrylate, 1.26 grams 1-NOEA, 1.35 grams
acrylic acid, 42 grams acetone, and 0.036 grams VAZO.TM. 67 free
radical initiator were charged into a glass bottle and polymerized
as described in Method A. Measured % solids were 27.5%. Refractive
index, shear, and adhesion results are given in Table II.
Example 6 (BA/AA/1-NOEA 82.5/7.5/10)
[0098] 14.85 grams butyl acrylate, 1.8 grams 1-NOEA, 1.35 grams
acrylic acid, 42 grams acetone, and 0.036 grams VAZO.TM. 67 free
radical initiator were charged into a glass bottle and polymerized
as described in Method A. Measured % solids was 27.5%. Refractive
index, shear, and adhesion results are given in Table II.
Example 7 (BA/AA/1-NOEA 79.5/7.5/13)
[0099] 14.31 grams butyl acrylate, 2.34 grams 1-NOEA, 1.35 grams
acrylic acid, 42 grams acetone, and 0.036 grams VAZO.TM. 67 free
radical initiator were charged into a glass bottle and polymerized
as described in Method A. Measured % solids were 27.6%. Refractive
index, shear, and adhesion results are given in Table II.
Example 8 (BA/AA/DBpNPA 72.5/7.5/20)
[0100] 13.05 grams butyl acrylate, 3.6 grams DBpNPA, 1.35 grams
acrylic acid, 42 grams acetone, and 0.036 grams VAZO.TM. 67 free
radical initiator were charged into a glass bottle and polymerized
as described in Method A. Measured % solids was 29.0%. Refractive
index, shear, and adhesion results are given in Table II.
Example 9 (BA/AA/DBpNPA 52.5/7.5/40)
[0101] 9.45 grams butyl acrylate, 7.2 grams DBpNPA, 1.35 grams
acrylic acid, 42 grams acetone, and 0.036 grams VAZO.TM. 67 free
radical initiator were charged into a glass bottle and polymerized
as described in Method A. Measured % solids was 28.0%. Refractive
index, shear, and adhesion results are given in Table II.
Example 10 (BA/AA/DBiPPHA 68/2/30)
[0102] 11.42 grams butyl acrylate, 5.04 grams DBiPPHA, 0.34 grams
acrylic acid, 42.7 grams ethyl acetate, 0.432 grams isopropyl
alcohol, and 0.025 grams VAZO.TM. 67 free radical initiator were
charged into a glass bottle and polymerized as described according
to Method A. 0.1% by weight N,N'-bis-1,2-propyleneisophthalamide
crosslinker was added to just prior to coating. Refractive index,
shear, and adhesion results are given in Table II.
Example 11 (BA/AA/DBiPPHA 38/2/60)
[0103] 6.38 grams butyl acrylate, 10.08 grams DBiPPHA, 0.34 grams
acrylic acid, 42.3 grams ethyl acetate, 0.864 grams isopropyl
alcohol, and 0.025 grams VAZO.TM. 67 free radical initiator were
charged into a glass bottle and polymerized as described according
to Method A. 0.1% by weight N,N'-bis-1,2-propyleneisophthalamide
crosslinker was added to just prior to coating. Refractive index,
shear, and adhesion results are given in Table II.
Example 12 (TOA/AA/PTEA 68/2/30)
[0104] 16.32 grams iso-octyl acrylate, 7.2 grams PTEA, 0.48 grams
acrylic acid, 36 grams ethyl acetate, and 0.048 grams VAZO.TM. 67
free radical initiator were charged into a glass bottle and
polymerized as described according to Method A. Refractive index,
shear, and adhesion results are given in Table II.
Example 13 (IOA/AA/PTEA 58/2/40)
[0105] 13.92 grams iso-octyl acrylate, 9.6 grams PTEA, 0.48 grams
acrylic acid, 36 grams ethyl acetate, and 0.048 grams VAZO.TM. 67
free radical initiator were charged into a glass bottle and
polymerized as described according to Method A. Refractive index,
shear, and adhesion results are given in Table II.
Example 14 (IOA/AA/PTEA 48/2/50)
[0106] 11.52 grams iso-octyl acrylate, 12 grams PTEA, 0.48 grams
acrylic acid, 36 grams ethyl acetate, and 0.048 grams VAZO.TM. 67
free radical initiator were charged into a glass bottle and
polymerized as described according to Method A. Refractive index,
shear, and adhesion results are given in Table II.
Example 15 (BA/AA/1-NOEA 75/5/20)
[0107] 37.4 grams deionized water, 0.40 gram RHODOCAL DS-10.TM.,
18.75 grams butyl acrylate, 5.0 grams 1-NOEA, 1.25 grams acrylic
acid, and 0.05 gram K.sub.2S.sub.2O.sub.8 were mixed, emulsified
and polymerized as described in Method B. Refractive index, shear,
and adhesion results are given in Table II.
Example 16 (BA/AA/1-NOEA 61/6/33)
[0108] 37.4 grams deionized water, 0.40 gram RHODOCAL DS-10.TM.,
13.75 grams butyl acrylate, 7.5 grams 1-NOEA, 1.25 grams acrylic
acid, and 0.05 gram K.sub.2S.sub.2O.sub.8 were mixed, emulsified
and polymerized as described in Method B. Refractive index, shear,
and adhesion results are given in Table II.
Examples 17-29 and Comparative Example C-2
[0109] Comparative Example C-2 and Examples 17-29 were prepared
according to Method C using the monomer components noted in Table I
below. A premix syrup of 90 parts IOA and 10 parts AA was prepared
for these examples. All values in Table I are parts by weight based
on a total of 100 parts monomer. Refractive index, shear, and
adhesion results are given in Table II. TABLE-US-00002 TABLE I
IOA/AA Syrup Example (90/10) DBiPPHA DBsBPHA PEA C-2 100 17 80 20
18 60 40 19 40 60 20 20 80 21 100 22 80 20 23 60 40 24 40 60 25 20
80 26 100 27 80 20 28 60 40 29 40 60
Example 30 (DBsBPHA/EB-9220 99/1)
[0110] A PSA adhesive composition was prepared by mixing 99 parts
DBsBPHA, 1 part EB-9220, a hexa-functional aromatic urethane
acrylate, and 1.5 parts of TPO photoinitiator (1.5% of total
monomer weight) in an appropriately sized container. The mixture
was warmed to 65.degree. C. for 15 minutes and then mixed again.
The mixture was coated on a polyester film using a knife coater to
a thickness of approximately 25 microns. The coated film
construction was passed under a 300 watt/cm UV lamp at a speed of
20 ft/min (6.1 m/min) and then heated in a 100.degree. C. oven for
1 minute. Refractive index, shear, and adhesion results are given
in Table II.
Example 31 (DBiPPHA/EB-9220 99/I)
[0111] A PSA adhesive composition was prepared as described in
Example 30 with the exception that DBiPPHA was used instead of
DBsBPHA. Refractive index, shear, and adhesion results are given in
Table II. TABLE-US-00003 TABLE II Example Adhesion Formula PSA Type
Refractive Index Shear (min) N/100 mm Comparative Example C-1
Solution 1.4684 4.75 71 BA/AA (92.5/7.5) Example 1 Solution 1.4913
10.80 59 BA/AA/1-NOHA(72.5/7.5/20) Example 2 Solution 1.5141 32.80
69 BA/AA/1-NOHA(52.5/7.5/40) Example 3 Solution 1.4978 57.80 74
BA/AA/1-NOEA (72.5/7.5/20) Example 4 Solution 1.5236 749 15
BA/AA/1-NOEA(52.5/7.5/40) Example 5 Solution 1.4795 38 67
BA/AA/1-NOEA (85.5/7.5/7) Example 6 Solution 1.4848 39 70
BA/AA/1-NOEA (82.5/7.5/10) Example 7 Solution 1.4902 36 77
BA/AA/1-NOEA (79.5/7.5/13) Example 8 Solution 1.4900 125 17
BA/AA/DBpNPA (72.5/7.5/20) Example 9 Solution 1.5137 3842 2
BA/AA/DBpNPA (52.5/7.5/40) Example 10 Solution 1.4886 9.0 55
BA/AA/DBiPPHA (68/2/30) Example 11 Solution 1.5148 5 81
BA/AA/DBiPPHA (38/2/60) Example 12 Solution 1.5007 5.35 67
IOA/AA/PTEA (68/2/30) Example 13 Solution 1.5112 6.90 68
IOA/AA/PTEA (58/2/40) Example 14 Solution 1.5256 6.80 64
IOA/AA/PTEA (48/2/50) Example 15 Emulsion 1.4963 70 52 BA/AA/1-NOEA
(75/5/20) Example 16 Emulsion 1.5176 230 47 BA/AA/1-NOEA (61/6/33)
Comparative Example C-2 Bulk 1.4704 105 69 IOA/AA (90/10) Example
17 Bulk 1.4841 40 75 IOA/AA/DBiPPHA (72/8/20) Example 18 Bulk
1.4965 4,000 82 IOA/AA/DBiPPHA (54/6/40) Example 19 Bulk 1.5134
7,600 90 IOA/AA/DBiPPHA (36/4/60) Example 20 Bulk 1.5309 2,500 91
IOA/AA/DBiPPHA (18/2/80) Example 21 Bulk 1.5568 3,200 63 DBiPPHA
(100) Example 22 Bulk 1.4834 10,000+ 62 IOA/AA/DBsBPHA (72/8/20)
Example 23 Bulk 1.4976 10,000+ 57 IOA/AA/DBsBPHA (54/6/40) Example
24 Bulk 1.5132 10,000+ 60 IOA/AA/DBsBPHA (36/4/60) Example 25 Bulk
1.5283 7,600 48 IOA/AA/DBsBPHA (18/2/80) Example 26 Bulk 1.5532
10,000+ 40 DBsBPHA (100) Example 27 Bulk 1.4856 10,000+ 46
IOA/AA/PEA (72/8/20) Example 28 Bulk 1.4976 10,000+ 48 IOA/AA/PEA
(54/6/40) Example 29 Bulk 1.5154 10,000+ 51 IOA/AA/PEA (36/4/60)
Example 30 Bulk 1.5544 914 37 DBsBPHA/EB-9220 (99/1) Example 31
Bulk 1.5580 1079 30 DBiPPHA/EB-9220 (99/1)
[0112] Various modifications and alterations to this invention will
become apparent to those skilled in the art without departing from
the scope and spirit of this invention. It should be understood
that this invention is not intended to be unduly limited by the
illustrative embodiments and examples set forth herein and that
such examples and embodiments are presented by way of example only
with the scope of the invention intended to be limited only by the
claims as set forth herein as follows.
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