U.S. patent application number 11/702306 was filed with the patent office on 2007-06-14 for adhesives comprising olefin copolymers.
This patent application is currently assigned to The Dow Chemical Company. Invention is credited to Jimmy D. Allen, William L. Bunnelle, Malcolm F. Finlayson, Thomas F. Harleysville, Michael S. Keehr, Keith C. Knutson, Mark S. Kroll, David B. Malcolm, Deepak R. Parikh, Cyndi L. Rickey, Eugene R. Simmons, David R. Speth, Selim Yalvac.
Application Number | 20070135563 11/702306 |
Document ID | / |
Family ID | 27087588 |
Filed Date | 2007-06-14 |
United States Patent
Application |
20070135563 |
Kind Code |
A1 |
Simmons; Eugene R. ; et
al. |
June 14, 2007 |
Adhesives comprising olefin copolymers
Abstract
Disclosed are adhesives and processes for preparing the same,
comprising at least one first homogeneous ethylene/.alpha.-olefin
interpolymer, and optionally at least one tackifier, and optionally
at least one plasticizer. The claimed adhesives are useful as
adhesives such as are employed in various applications, such as in
masking tape, clear office tape, labels, decals, bandages,
decorative and protective sheets (such as shelf and drawer liners),
floor tiles, sanitary napkin/incontinence device placement strips,
sun control films, the joining of gaskets to automobile windows,
packaging, bookbinding, construction of nonwoven articles, and
insulation bonding.
Inventors: |
Simmons; Eugene R.; (Vadnais
Heights, MN) ; Bunnelle; William L.; (Circle Pines,
MN) ; Malcolm; David B.; (Maplewood, MN) ;
Knutson; Keith C.; (Shoreview, MN) ; Harleysville;
Thomas F.; (Woodbury, MN) ; Kroll; Mark S.;
(Arden Hills, MN) ; Keehr; Michael S.; (Blaine,
MN) ; Parikh; Deepak R.; (Singapore, SG) ;
Allen; Jimmy D.; (Brazoria, TX) ; Speth; David
R.; (Upper Arlington, OH) ; Yalvac; Selim;
(Pearland, TX) ; Finlayson; Malcolm F.; (Houston,
TX) ; Rickey; Cyndi L.; (Lake Jackson, TX) |
Correspondence
Address: |
THE DOW CHEMICAL COMPANY
INTELLECTUAL PROPERTY SECTION,
P. O. BOX 1967
MIDLAND
MI
48641-1967
US
|
Assignee: |
The Dow Chemical Company
Midland
MI
|
Family ID: |
27087588 |
Appl. No.: |
11/702306 |
Filed: |
February 5, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
08973779 |
Jan 8, 1998 |
7199180 |
|
|
PCT/US97/04161 |
Mar 14, 1997 |
|
|
|
11702306 |
Feb 5, 2007 |
|
|
|
08615750 |
Mar 14, 1996 |
|
|
|
08973779 |
Jan 8, 1998 |
|
|
|
08616406 |
Mar 14, 1996 |
|
|
|
08973779 |
Jan 8, 1998 |
|
|
|
Current U.S.
Class: |
524/570 ;
524/271; 524/274; 524/482; 524/484; 524/485; 524/486; 524/487;
524/505; 524/522; 524/523; 524/524; 524/528; 524/579 |
Current CPC
Class: |
C08L 2666/02 20130101;
C08L 77/00 20130101; C08L 23/0869 20130101; C09J 123/0815 20130101;
C08K 5/0016 20130101; C08L 23/04 20130101; C08F 210/16 20130101;
B32B 7/12 20130101; C09J 7/35 20180101; C08K 5/0008 20130101; C09J
2423/00 20130101; C08L 23/0853 20130101; C08L 23/04 20130101; C08L
2666/04 20130101; C08F 210/16 20130101; C08F 210/14 20130101; C08F
2500/08 20130101; C08F 2500/02 20130101; C08F 2500/03 20130101;
C08F 2500/12 20130101; C09J 123/0815 20130101; C08L 2666/02
20130101 |
Class at
Publication: |
524/570 ;
524/271; 524/274; 524/482; 524/484; 524/485; 524/486; 524/487;
524/505; 524/522; 524/523; 524/524; 524/528; 524/579 |
International
Class: |
B60C 1/00 20060101
B60C001/00 |
Claims
1-29. (canceled)
30. An adhesive comprising: (a) from 5 to 95 weight percent of at
least one homogeneous ethylene/.alpha.-olefin interpolymer,
characterized as having a density from 0.850 to 0.885 g/cm.sup.3;
(b) from 0 to 95 weight percent of at least one tackifier; (c) from
0 to about 90 weight percent of at least one plasticizer; and (d)
from 0 to 90 weight percent of at least one wax; wherein the sum of
components (b), (c), and (d) comprises 5 to 95 weight percent of
said adhesive.
31. The adhesive of claim 30, wherein the adhesive comprises less
then 30 weight percent of the at least one interpolymer, and from
10 to 75 weight percent of the at least one tackifier.
32. The adhesive of claim 30, wherein the adhesive comprises
greater than, or equal to, 30 weight percent of the at least one
interpolymer, and comprises less than 30 weight percent of the at
least one tackifier.
33. The adhesive of claim 30, wherein the adhesive comprises less
than 30 weight percent of the at least one plasticizer.
34. The adhesive of claim 30, wherein the adhesive comprises less
than, or equal to, 60 weight percent of the at least one wax.
35. The adhesive of claim 30, wherein the adhesive comprises less
than 30 weight percent of the at least one interpolymer, and
wherein the at least one interpolymer has a melt index (I2 at
190.degree. C.) less than, or equal to, 50 g/10 min.
36. The adhesive of claim 30, wherein the adhesive comprises
greater than 30 weight percent of the at least one interpolymer,
and wherein the at least one interpolymer has a melt index (I2 at
190.degree. C.) less than, or equal to, 500 g/10 min.
37. The adhesive of claim 30, wherein the at least one interpolymer
has a molecular weight distribution (Mw/Mn) from 1.5 to 2.5.
38. The adhesive of claim 30, wherein the at least one interpolymer
has a number average molecular weight (Mn) greater than, or equal
to, 3,000 g/mole.
39. The adhesive of claim 30, wherein the at least one interpolymer
has a number average molecular weight (Mn) less than 11,000
g/mole.
40. The adhesive of claim 30, wherein the ethylene/.alpha.-olefin
interpolymer is prepared from ethylene and at least one
C.sub.3-C.sub.20 .alpha.-olefin.
41. A nonwoven article comprising a body fluid impermeable barrier
bonded by the adhesive of claim 30.
42. The nonwoven article of claim 41, wherein said article
comprises disposables including disposable diapers and feminine
napkins.
43. An article comprising the adhesive of claim 30.
44. An adhesive consisting essentially of: (a) from 5 to 95 weight
percent of at least one homogeneous ethylene/.alpha.-olefin
interpolymer, characterized as having a density from 0.850 to 0.885
g/cm.sup.3 and a number average molecular weight of from 3,000 to
100,000; (b) from 5 to about 90 weight percent of at least one
plasticizer chosen from hydrocarbon oils, polybutene, or liquid
elastomers; (c) from 0 to 95 weight percent of at least one
tackifier; and (d) from 0 to 90 weight percent of at least one
wax.
45. The adhesive of claim 44, wherein said hydrocarbon oils are
paraffinic or napthenic oils with low aromatic content.
46. A nonwoven article comprising a body fluid impermeable barrier
bonded by the adhesive composition of claim 44.
47. The nonwoven article of claim 46, wherein said article
comprises disposables including disposable diapers and feminine
napkins.
48. An article comprising the adhesive of claim 44.
49. An adhesive comprising: (a) from 5 to 95 weight percent of at
least one homogeneous ethylene/.alpha.-olefin interpolymer,
characterized as having a weight average molecular weight (Mw) less
than 20,000 g/mole; (b) from 0 to 95 weight percent of at least one
tackifier; (c) from 0 to about 90 weight percent of at least one
plasticizer; and (d) from 0 to 90 weight percent of at least one
wax; wherein the sum of components (b), (c), and (d) comprises 5 to
95 weight percent of said adhesive.
Description
[0001] The subject invention relates to hot melt adhesives
comprising at least one homogeneous linear or substantially linear
interpolymer of ethylene with at least one C.sub.3-C.sub.20
.alpha.-olefin, further characterized by each said interpolymer
having a polydispersity less than about 2.5, and articles
constructed therefrom. Such hot melt adhesives are useful in a
variety of applications including but not limited to bookbinding,
case and carton seal, packaging, glue sticks, foam in place
gaskets, and particularly pressure sensitive adhesives for tag and
label adhesives, palletizing adhesives, skin attachment adhesives,
positioning adhesives, diaper tapes and construction adhesives for
assembly of nonwoven articles, etc.
[0002] Historically, adhesives have been based on any of five
polymer classes: polyethylene; ethylene vinyl acetate; natural
rubber or block copolymer elastomers (for example,
styrene-isoprene-styrene block copolymers,
styrene-butadiene-styrene block copolymers, and styrene-butadiene
random copolymers); acrylics (such as interpolymers of butyl
acrylate, 2-ethyl hexyl acrylate, and methyl methacrylate); and
amorphous polyolefins, and the like, amorphous C.sub.3 and greater
.alpha.-olefins, such as atactic polypropylene, copolymers of
propylene and higher order .alpha.-olefins, and polybutene.
[0003] Linear low density polyethylene and low density polyethylene
have been used as a base polymer in a variety of hot melt
adhesives, particularly for case and carton sealing, wherein upon
cooling and solidifying the resulting adhesive is relatively tack
free. Polyethylene waxes are also used in formulating hot melt
adhesives. Linear low density polyethylene and low density
polyethylene, as base raw materials for adhesives, suffer from the
disadvantage that due to their crystalline nature, they tend to be
very stiff and have poor cold temperature properties. In addition
to poor cold temperature properties, polyethylene case and carton
seal adhesives have limited hot tack, resulting in low peel
adhesion failure temperatures. Further, polyethylene has had
limited utility as a base polymer in formulating pressure sensitive
adhesives, particularly due to poor oil holding capability.
[0004] Ethylene vinyl acetate (EVA) based systems are limited in
that as higher vinyl acetate levels are selected, although
crystallinity decreases and elastomeric performance increase,
compatibility with formulation ingredients decreases. Accordingly,
EVA is typically utilized in non-pressure sensitive adhesive
applications.
[0005] Block copolymer elastomers provide an excellent balance of
tack, peel resistance and creep resistance properties. Such
elastomers may be utilized in solvent-based, water-born, and hot
melt pressure sensitive adhesives. However, adhesive systems based
on such elastomers are disadvantageous in that the sites of
unsaturation in the block copolymer backbone make the adhesive
susceptible to degradation by the action of oxygen and ultraviolet
light.
[0006] Acrylic systems, while stable to oxygen and ultraviolet
light, are inferior to block copolymer elastomer systems in terms
of the balance of tack, peel and creep resistance. Further, such
systems are typically available only in the solvent-based and
water-borne systems, making them further disadvantageous for the
reasons set forth above.
[0007] Amorphous polyolefins have been utilized in adhesive
systems, at least in part to provide improved stability to oxygen
and ultraviolet light, as compared to block copolymer elastomer
systems. Due to the fact that amorphous polyolefins have been
historically available as reaction by-products, they have been
inconsistent in grade, composition, and viscosity, leading to a
poor balance of properties. In particular, poly-1-butene has a
tendency to slowly crystallize after application to the substrate,
leading to a profound loss of tack. When oil is added to increase
tack, the oil tends to migrate out of the adhesive into the backing
layer or the substrate. Due to the heterogeneity of branch
distribution and broad molecular weight distribution, adhesives
comprising less than 40 weight percent amorphous polyolefins tend
to be weak cohesively, suffer from low tensile strength, and leave
a residue on the substrate surface after peeling. To compensate for
their inherent poor cohesive strength, adhesives based on amorphous
polyolefins tend to have a high concentration of amorphous
polyolefin, resulting in a relatively high viscosity. Such high
viscosity renders amorphous polyolefin-based adhesives unsuitable
for use with spray application equipment at typical application
temperatures of less than about 325.degree. F. (167.degree. C.).
Amorphous polyolefins further disadvantageously tend to have
unpredictable aging characteristics due to an uncontrolled
secondary crystallization caused by the random chain length and
distribution of the comonomer branching.
[0008] Homogeneous linear and substantially linear ethylene
polymers prepared using single-site or metallocene catalysts have
been recently introduced. Homogeneous ethylene polymers are
characterized as having a narrow molecular weight distribution and
a uniform short-chain branching distribution. In the case of
substantially linear ethylene polymers, such homogeneous ethylene
polymers are further characterized as having long chain branching.
Substantially linear ethylene polymers are commercially available
from The Dow Chemical Company as Affinity.TM. polyolefin
plastomers, which are produced using Dow's Insite.TM. technology.
Homogeneous linear ethylene polymers are available from Exxon
Chemical Company under the trade name Exact.RTM. plastomers.
[0009] Tse et al., U.S. Pat. No. 5,530,054, claims a hot melt
adhesive composition consisting essentially of: (a) 30-70 weight
percent of a copolymer of ethylene and about 6 to about 30 weight
percent of a C.sub.4 to C.sub.20 .alpha.-olefin produced in the
presence of a catalyst composition comprising a metallocene and an
alumoxane and having an M.sub.w of from about 20,000 to about
100,000; and (b) a hydrocarbon tackifier which is selected from a
recited list. Exemplified are compositions consisting of 45 weight
percent of ethylene/butene-1 copolymer having a specific gravity of
either 0.898 g/cm.sup.3 or 0.901 g/cm.sup.3.
[0010] Tse et al, U.S. Pat. No. 5,548,014, claims a hot melt
adhesive composition comprising a blend of ethylene/.alpha.-olefin
copolymers wherein the first copolymer has a Ma from about 20,000
to about 39,000 and the second copolymer has a MN from about 40,000
to about 100,000. Each of the hot melt adhesives exemplified
comprises a blend of copolymers, contains 45 weight percent
copolymer, with at least one of the copolymers having a
polydispersity greater than 2.5. Furthermore, the lowest density
copolymer exemplified has a specific gravity of 0.894
g/cm.sup.3.
[0011] However, Tse, in Application of Adhesion Model for
Developing Hot Melt Adhesives Bonded to Polyolefin Surfaces,
Journal of Adhesion, Vol. 48, Issue 1-4, pp. 149 to 167 (1995),
notes that compared with hot melt adhesives based on ethylene/vinyl
acetate copolymer, hot melt adhesives based on homogeneous linear
ethylene/.alpha.-olefin interpolymers show higher viscosity and
inferior tensile strength, but better bond strength to polyolefin
surfaces, higher strain at break and lower yield stress.
[0012] Lakshmanan et al., U.S. Pat. No. 5,397,843, teaches blended
polymer compositions comprising an admixture of a copolymer of
ethylene and an .alpha.-olefin and an amorphous polypropylene
and/or amorphous polyolefin, or mixtures thereof. A hot melt
adhesive is claimed comprising from 20 to 97.5 percent of a
traditional polyolefin. The examples set forth in Lakshmanan teach
compositions with high concentrations, at least 42.5 percent by
weight, of blended polymers and tend to suffer from the previously
described disadvantages of traditional polyolefins. The single
ethylene and .alpha.-olefin exemplified is "Flexomer 9042" from
Union Carbide, having a 1-butene content of 15 weight percent, a
melt index of 5.0 g/10 minute, a crystallinity level of 26 percent
and a density of 0.900 g/cm.sup.3. The "Flexomer" polyolefin from
Union Carbide depicted in the examples is believed to have a
polydispersity greater than 2.5.
[0013] Those in industry would find great advantage in hot melt
adhesives based on homogeneous ethylene/.alpha.-olefin
interpolymers which have a balance of properties which is superior
to those which have been previously attained.
[0014] Accordingly, the subject invention pertains to an adhesive
comprising: [0015] (a) from 5 to 95 weight percent of at least one
interpolymer which is a homogeneous linear or substantially linear
ethylene/.alpha.-olefin interpolymer characterized as having a
density from 0.850 to 0.885 g/cm.sup.3; [0016] (b) from 0 to 95
weight percent of at least one tackifier; [0017] (c) from 0 to
about 90 weight percent of at least one plasticizer; and [0018] (d)
from 0 to 90 weight percent of at least one wax; wherein the sum of
components (b), (c), and (d) comprises 5 to 95 weight percent of
said adhesive composition.
[0019] The subject invention further pertains to a hot melt
adhesive composition comprising: [0020] (a) a homogeneous linear
interpolymer of ethylene and greater than 30 weight percent as
determined by mass balance, based on the total weight of ethylene
and comonomer, of an .alpha.-olefin comonomer having from 3 to 20
carbon atoms, which copolymer has a weight average molecular weight
(M.sub.w) of from 2000 to 100,000; and [0021] (b) a tackifier.
[0022] The subject invention further pertains to an adhesive
comprising: [0023] (a) from 5 to 95 weight percent of at least one
interpolymer which is a homogeneous linear or substantially linear
ethylene/.alpha.-olefin interpolymer characterized as having a
weight average molecular weight (M.sub.w) of less than 20,000;
[0024] (b) from 0 to 95 weight percent of at least one tackifier;
[0025] (c) from 0 to about 90 weight percent of at least one
plasticizer; and [0026] (d) from 0 to 90 weight percent of at least
one wax; wherein the sum of components (b), (c), and (d) comprises
5 to 95 weight percent of said adhesive composition.
[0027] The subject invention further provides various adhesive
compositions which are targeted for use in various adhesive
applications. In this regard, the subject invention further
pertains to a hot melt adhesive comprising: [0028] (a) from 30 to
97 weight percent of at least one first polymer which is an
interpolymer of ethylene and at one C.sub.3-C.sub.20
.alpha.-olefin, said at least one first polymer being characterized
as having: [0029] (i) a density of from 0.850 to 0.885 g/cm.sup.3,
[0030] (iii) a number average molecular weight as determined by gel
permeation chromatography, of less than 20,000; [0031] (b) from 3
to 70 weight percent of at least one second polymer which is an
ethylene homopolymer or an interpolymer of ethylene with at least
C.sub.3-C.sub.20 .alpha.-olefin, the at least one second polymer
being characterized as having: [0032] (i) a density of from 0.910
to 0.970 g/cm.sup.3, [0033] (ii) a number average molecular weight
as determined by gel permeation chromatography, of less than 6,000;
and [0034] (c) from 0 to 70 weight percent of one or more
tackifiers.
[0035] In one preferred embodiment, the adhesive compositions of
the present invention are pressure sensitive adhesives, which are
characterized as having a storage modulus (G') at 25.degree. C. of
less than 1.times.10.sup.7 dynes/cm.sup.2 (1 MPa) and a glass
transition temperature (T.sub.g) of from -65.degree. C. to
30.degree. C., more preferably from 0.degree. C. to 20.degree. C.
and most preferably from 10.degree. C. to 20.degree. C.
[0036] Optionally, the adhesive composition of the invention may
further contain an additional polymer selected from the group
consisting of compatible elastomers, such as a thermoplastic block
copolymer, polyamides, amorphous or crystalline polyolefins such as
polypropylene, polybutylene or polyethylene, wherein M.sub.w is
greater than about 3000; interpolymers or ionomers of ethylene with
at least one comonomer selected from the group consisting of vinyl
esters of a saturated carboxylic acid having up to 4 carbon atoms,
unsaturated mono- or dicarboxylic acids of 3 to 5 carbon atoms, or
salts or esters thereof; and mixtures thereof.
[0037] In one embodiment, the invention provides hot melt adhesives
comprising homogeneous ethylene polymers in conjunction with low
density polyethylene or heterogeneously branched linear low density
polyethylene having a weight average molecular weight (M.sub.w)
greater than about 3000, ethylene-vinyl acetate (EVA), or a
polyamide.
[0038] Optionally, the at least one ethylenel.alpha.-olefin
interpolymer utilized in the hot melt adhesives of the invention
may be provided in conjunction with a second homogeneous linear or
substantially linear interpolymer, which differs in at least one
physical property selected from the group consisting of density,
comonomer type, number average molecular weight and combinations
thereof. The interpolymers may be blended at ratios ranging from
0.05 to 20 ratio by weight to 20 to 0.05 ratio by weight.
[0039] In a preferred embodiment, a first homogeneous
ethylene/.alpha.-olefin interpolymer having a density less than
0.870 g/cm.sup.3 is provided in conjunction with a second
homogeneous ethylene/.alpha.-olefin interpolymer having a density
greater than 0.900 g/cm.sup.3.
[0040] In one particularly preferred embodiment, the subject
invention provides a hot melt adhesive comprising: [0041] (a) from
5-95 weight percent of a polymer mixture which in turn comprises:
[0042] (i) from 30 to 97 weight percent of at least one first
polymer which is an interpolymer of ethylene and at least one
C.sub.3-C.sub.20 .alpha.-olefin, the at least one first polymer
being characterized as having a density of from 0.850 to 0.920
g/cm.sup.3, and a number average molecular weight as determined by
gel permeation chromatography, of less than 80,000; and [0043] (ii)
from 3 to 70 weight percent of at least one second polymer which is
an ethylene homopolymer or an interpolymer of ethylene and at least
one C.sub.3-C.sub.20 .alpha.-olefin, the at least one second
polymer being characterized as having a density of from 0.910 to
0.970 g/cm.sup.3 and a number average molecular weight as
determined by gel permeation chromatography, of less than 6,000;
and [0044] (b) from 0 to 95 weight percent of at least one
tackifier; [0045] (c) from 0 to about 90 weight percent of at least
one plasticizer; and [0046] (d) from 0 to 90 weight percent of at
least one wax; wherein the density of the at least one first
polymer and the at least one second polymer differ by at least 0.01
g/cm.sup.3 and the number average molecular weights of the at least
one first polymer and the at least one second polymer differ by at
least 5000.
[0047] The subject invention further provides a polymerization
process comprising: [0048] (a) reacting by contacting ethylene and
at least one C.sub.3-C.sub.20 .alpha.-olefin, under solution
polymerization conditions, in the presence of a single site
catalyst composition, in at least one reactor, to produce a
solution of a first polymer which is an interpolymer of ethylene
and the at least one C.sub.3-C.sub.20 .alpha.-olefin, the at least
one first polymer being characterized as having: [0049] (i) a
density of from 0.850 to 0.920 g/cm.sup.3, [0050] (ii) a number
average molecular weight as determined by gel permeation
chromatography, of from 5,000 to 80,000; and [0051] (iii) a
molecular weight distribution (M.sub.w/M.sub.n) of from 1.5 to 2.5;
[0052] (b) reacting by contacting ethylene and, optionally, at
least one C.sub.3-C.sub.20 .alpha.-olefin, under solution
polymerization conditions, in the presence of a single site
catalyst composition or a heterogeneous catalyst composition, in at
least one other reactor, to produce a solution of at least one
second polymer, which is an ethylene homopolymer or an interpolymer
of ethylene with the at least one C.sub.3-C.sub.20 .alpha.-olefin,
the at least one second polymer being characterized as having:
[0053] (i) a density of from 0.910 to 0.970 g/cm.sup.3, [0054] (ii)
a number average molecular weight as determined by gel permeation
chromatography, of less than 6,000, and [0055] (iii) a molecular
weight distribution (M.sub.w/M.sub.n) of from 1.5 to 2.5; [0056]
(c) combining the solution of the first reactor with the solution
of the second reactor to form a solution of a blend; [0057] (d)
removing the solvent from the solution of a blend of step (c) and
recovering the blend; and [0058] (e) optionally introducing a
tackifier into the reactor of step (a), the reactor of step (b), or
at any point subsequent to the reacting of step (b).
[0059] In general, the adhesive composition of the present
invention exhibits improved properties, including excellent
viscosity and color stability, particularly at elevated
temperatures; high cohesive strength and excellent oil holding
power, allowing the use of relatively low concentrations of the
employed homogeneous linear or substantially linear interpolymers;
compatibility with a wide range of other polymers, tackifiers, and
plasticizers, particularly waxes; and improved adhesion to
polyolefin substrates such as polyolefin based containers and
films. The adhesive composition of the present invention is also
surmised to be repulpable and be able to be used at lower coating
weights due to its low density, as well as be resistant to
degradation caused by exposure to ultraviolet radiation.
[0060] The adhesive of the present invention is useful for a
variety of articles such as tapes, labels, disposables, including
disposable diapers and feminine napkins, as well as for
bookbinding, packaging, and skin attachment adhesives for medical
tapes and devices. Improved adhesion to films such as low density
polyethylene (LDPE), high density polyethylene (HDPE), shrink wrap
and particularly films prepared from homogeneous ethylene polymers,
in combination with good spray properties, allows the adhesive
compositions of the present invention to be particularly useful for
the nonwoven industry in the manufacture of disposable diapers,
feminine napkins, and surgical drapes.
[0061] In another preferred embodiment, homogeneous ethylene
polymers have further been found to be useful alone or in
combination with other ingredients such as tackifiers and waxes as
a coextrusion coating or a thermoplastic packaging film which is
meltable and blendable with the adhesive composition, such as a
batch inclusion bag. This aspect is particularly advantageous when
the polymer of the adhesive composition, the coextrusion coating,
and/or the thermoplastic packaging film are of the same polymer
chemistry, insuring mutual compatibility.
[0062] These and other embodiments are more fully described in the
following detailed description.
[0063] The adhesives of the invention comprise at least one
homogeneous ethylene/.alpha.-olefin interpolymer which is an
interpolymer of ethylene and at least one C.sub.3-C.sub.20
.alpha.-olefin. The term "interpolymer" is used herein to indicate
a copolymer, or .alpha.terpolymer, or a higher order polymer. That
is, at least one other comonomer is polymerized with ethylene to
make the interpolymer.
[0064] The homogeneous ethylene/.alpha.-olefin interpolymer is a
homogeneous linear or substantially linear ethylene/.alpha.-olefin
interpolymer. By the term "homogenous", it is meant that any
comonomer is randomly distributed within a given interpolymer
molecule and substantially all of the interpolymer molecules have
the same ethylene/comonomer ratio within that interpolymer. The
melting peak of homogeneous linear and substantially linear
ethylene polymers, as obtained using differential scanning
calorimetry, will broaden as the density decreases and/or as the
number average molecular weight decreases. However, unlike
heterogeneous polymers, when a homogeneous polymer has a melting
peak greater than 115.degree. C. (such as is the case of polymers
having a density greater than 0.940 g/cm.sup.3), it does not
additionally have a distinct lower temperature melting peak.
[0065] In addition or in the alternative, the homogeneity of the
polymer may be described by the SCBDI (Short Chain Branching
Distribution Index) or CDBI (Composition Distribution Breadth
Index), which are defined as the weight percent of the polymer
molecules having a comonomer content within 50 percent of the
median total molar comonomer content. The SCBDI of a polymer is
readily calculated from data obtained from techniques known in the
art, such as, for example, temperature rising elution fractionation
(abbreviated herein as "TREF"), which is described, for example, in
Wild et al., Journal of Polymer Science, Poly. Phys. Ed., Vol. 20,
p. 441 (1982), in U.S. Pat. No. 4,798,081 (Hazlitt et al.), or in
U.S. Pat. No. 5,089,321 (Chum et al.). The SCBDI or CDBI for the
homogeneous ethylenel.alpha.-olefin interpolymers useful in the
invention is preferably greater than 50 percent, more preferably
greater than 70 percent, with SCBDI's and CDBI of greater than 90
percent being easily attained.
[0066] The homogeneous ethylene/.alpha.-olefin interpolymers useful
in the invention are characterized as having a narrow molecular
weight distribution (M.sub.w/M.sub.n). For the homogeneous
ethylene/.alpha.-olefins useful in the adhesives of the invention,
the M.sub.w/M.sub.n is from 1.5 to 2.5, preferably from 1.8 to 2.2,
most preferably about 2.0.
[0067] Substantially linear ethylene interpolymers are homogeneous
interpolymers having long chain branching. Due to the presence of
such long chain branching, substantially linear ethylene
interpolymers are further characterized as having a melt flow ratio
(I.sub.10/I.sub.2) which may be varied independently of the
polydispersity index, and the like, the molecular weight
distribution M.sub.w/M.sub.n. This feature accords substantially
linear ethylene polymers with a high degree of processability
despite a narrow molecular weight distribution.
[0068] It is noted that substantially linear interpolymers useful
in the invention differ from low density polyethylene prepared in a
high pressure process. In one regard, whereas low density
polyethylene is an ethylene homopolymer having a density of from
0.900 to 0.935 g/cm.sup.3, the homogeneous linear and substantially
linear interpolymers useful in the invention require the presence
of a comonomer to reduce the density to the range of from 0.900 to
0.935 g/cm.sup.3.
[0069] The long chain branches of substantially linear ethylene
interpolymers have the same comonomer distribution as the
interpolymer backbone and can be as long as about the same length
as the length of the interpolymer backbone. When a substantially
linear ethylene/.alpha.-olefin interpolymer is employed in the
practice of the invention, such interpolymer will be characterized
as having an interpolymer backbone substituted with from 0.01 to 3
long chain branches per 1000 carbons.
[0070] Methods for determining the amount of long chain branching
present, both qualitatively and quantitatively, are known in the
art.
[0071] For qualitative methods for determining the presence of long
chain branching, see, for example, U.S. Pat. Nos. 5,272,236 and
5,278,272. As set forth therein, a gas extrusion rheometer (GER)
may be used to determine the rheological processing index (PI), the
critical shear rate at the onset of surface melt fracture, and the
critical shear stress at the onset of gross melt fracture, which in
turn indicate the presence or absence of long chain branching as
set forth below.
[0072] The gas extrusion rheometer useful in the determination of
rheological processing index (PI), the critical shear rate at the
onset of surface melt fracture, and the critical shear stress at
the onset of gross melt fracture, is described by M. Shida, R. N.
Shroff, and L. V. Cancio in Polymer Engineering Science, Vol. 17,
No. 11, p. 770 (1977), and in "Rheometers for Molten Plastics" by
John Dealy, published by Van Nostrand Reinhold co. (1982) on pp.
97-99. GER experiments are performed at a temperature of
190.degree. C., at nitrogen pressures between 250 and 5500 psig
(between 1.72 and 37.9 MPa) using a 0.0754 mm diameter, 20:1 L/D
die with an entrance angle of 180.degree..
[0073] For substantially linear ethylene interpolymers, the PI is
the apparent viscosity (in kpoise) of a material measured by GER at
an apparent shear stress of 2.15.times.10.sup.6 dynes/cm.sup.2
(0.215 MPa). Substantially linear ethylene interpolymers useful in
the invention will have a PI in the range of 0.01 kpoise to 50
kpoise, preferably 15 kpoise or less. Substantially linear ethylene
interpolymers have a PI which is less than or equal to 70 percent
of the PI of a linear ethylene interpolymer (either a Ziegler
polymerized polymer or a homogeneous linear ethylene interpolymer)
having the same comonomer or comonomers, and having an I.sub.2,
M.sub.w/M.sub.n, and density, each of which is within 10 percent of
that of the substantially linear ethylene interpolymer.
[0074] An apparent shear stress versus apparent shear rate plot may
be used to identify the melt fracture phenomena and to quantify the
critical shear rate and critical shear stress of ethylene polymers.
According to Ramamurthy, in the Journal of Rheology, 30(2), 1986,
pp. 337-357, above a certain critical flow rate, the observed
extrudate irregularities may be broadly classified into two main
types: surface melt fracture and gross melt fracture.
[0075] Surface melt fracture occurs under apparently steady flow
conditions and ranges in detail from loss of specular film gloss to
the more severe form of "sharksin." Herein, as determined using the
above-described gas extrusion rheometer, the onset of surface melt
fracture is characterized as the beginning of losing extrudate
gloss at which the surface roughness of the extrudate can only be
detected by magnification at 40 times. The critical shear rate at
the onset of surface melt fracture for a substantially linear
ethylene interpolymer is at least 50 percent greater than the
critical shear rate at the onset of surface melt fracture for a
linear ethylene polymer having the same comonomer or comonomers and
having an I.sub.2, M.sub.w/M.sub.n and density within ten percent
of that of the substantially linear ethylene polymer.
[0076] Gross melt fracture occurs at unsteady extrusion flow
conditions and ranges from regular (alternating rough and smooth,
helical, etc.) to random distortions. The critical shear stress at
the onset of gross melt fracture of substantially linear ethylene
interpolymers, especially those having a density greater than 0.910
g/cm.sup.3, is greater than 4.times.10.sup.6 dynes/cm.sup.2 (0.4
MPa).
[0077] The presence of long chain branching may further be
qualitatively determined by the Dow Rheology Index (DRI), which
expresses a polymer's "normalized relaxation time as the result of
long chain branching." (See, S. Lai and G. W. Knight, ANTEC '93
Proceedings, INSITE.TM. Technology Polyolefins (SLEP)--New Rules in
the Structure/Rheology Relationship of Ethylene .alpha.-Olefin
Copolymers, New Orleans, La., May 1993. DRI values range from 0 for
polymers which do not have any measurable long chain branching,
such as Tafmer.TM. products available from Mitsui Petrochemical
Industries and Exact.TM. products available from Exxon Chemical
company) to about 15, and are independent of melt index. In
general, for low to medium pressure ethylene polymers, particular
at lower densities, DRI provides improved correlations to melt
elasticity and high shear flowability relative to correlations of
the same attempted with melt flow ratios. Substantially linear
ethylene interpolymers will have a DRI of preferably at least 0.1,
more preferably at least 0.5, and most preferably at least 0.8.
[0078] DRI may be calculated from the equation:
DRI=(3.652879*.tau..sub.o1.00649/.eta..sub.o-1)/10 where
.tau..sub.o is the characteristic relaxation time of the
interpolymer and .eta..sub.o is the zero shear viscosity of the
interpolymer. Both .tau..sub.o and .eta..sub.o are the "best fit"
values to the Cross equation, and the like,
.eta./.eta..sub.o=1/(1+(.gamma.*.tau..sub.o).sup.1-n) in which n is
the power law index of the material, and .eta. and .gamma. are the
measured viscosity and shear rate, respectively. Baseline
determination of viscosity and shear rate data are obtained using a
Rheometric Mechanical Spectrometer (RMS-800) under dynamic sweep
mode from 0.1 to 100 radians/second at 160.degree. C. and a gas
extrusion rheometer (GER) at extrusion pressures from 1,000 to
5,000 psi (6.89 to 34.5 MPa), which corresponds a shear stress of
from 0.086 to 0.43 MPa, using a 0.0754 mm diameter, 20:1 L/D die at
190.degree. C. Specific material determinations may be performed
from 140 to 190.degree. C. as required to accommodate melt index
variations.
[0079] For quantitative methods for determining the presence of
long chain branching, see, for example, U.S. Pat. No. 5,272,236 and
5,278,272; Randall (Rev. Macromol. Chem. Phys., C29 (2&3), p.
285-297), which discusses the measurement of long chain branching
using .sup.13C nuclear magnetic resonance spectroscopy, Zimm, G. H.
and Stockmayer, W. H., J. Chem. Phys., 17, 1301 (1949); and Rudin,
A., Modern Methods of Polymer Characterization, John Wiley &
Sons, New York (1991) pp. 103-112, which discuss the use of gel
permeation chromatography coupled with a low angle laser light
scattering detector (GPC-LALLS) and gel permeation chromatography
coupled with a differential viscometer detector (GPC-DV).
[0080] A. Willem deGroot and P. Steve Chum, both of The Dow
Chemical Company, at the Oct. 4, 1994 conference of the Federation
of Analytical Chemistry and Spectroscopy Society (FACSS) in St.
Louis, Mo., presented data demonstrating that GPC-DV is a useful
technique for quantifying the presence of long chain branches in
substantially linear ethylene polymers. In particular, deGroot and
Chum found that the presence of long chain branches in
substantially linear ethylene polymers correlated well with the
level of long chain branches measured using .sup.13C NMR.
[0081] Further, deGroot and Chum found that the presence of octene
does not change the hydrodynamic volume of the polyethylene samples
in solution and, as such, one can account for the molecular weight
increase attributable to octene short chain branches by knowing the
mole percent octene in the sample. By deconvoluting the
contribution to molecular weight increase attributable to 1-octene
short chain branches, deGroot and Chum showed that GPC-DV may be
used to quantify the level of long chain branches in substantially
linear ethylene/octene copolymers.
[0082] deGroot and Chum also showed that a plot of log(I.sub.2,
melt index) as a function of log (GPC weight average molecular
weight), as determined by GPC-DV, illustrates that the long chain
branching aspects (but not the extent of long chain branching) of
substantially linear ethylene polymers are comparable to those of
high pressure, highly branched low density polyethylene (LDPE) and
are clearly distinct from heterogeneously branched ethylene
polymers produced using Ziegler-type catalysts (such as linear low
density polyethylene and ultra low density polyethylene) as well as
from homogeneous linear ethylene polymers (such as Tafmer.TM.
products available from Mitsui Petrochemical Industries and
Exact.TM. products available from Exxon Chemical Company).
[0083] The first polymer will be an interpolymer of ethylene with
at least one comonomer selected from the group consisting of
C.sub.3-C.sub.20 .alpha.-olefins, non-conjugated dienes, and
cycloalkenes. Exemplary C.sub.3-C.sub.20 .alpha.-olefins include
propylene, isobutylene, 1-butene, 1-hexene, 4-methyl-1-pentene,
1-heptene, and 1-octene. Preferred C.sub.3-C.sub.20 .alpha.-olefins
include 1-butene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and
1-octene, more preferably 1-hexene and 1-octene. Exemplary
cycloalkenes include cyclopentene, cyclohexene, and cyclooctene.
The non-conjugated dienes suitable as comonomers, particularly in
the making of ethylene/.alpha.-olefin/diene terpolymers, are
typically non-conjugated dienes having from 6 to 15 carbon atoms.
Representative examples of suitable non-conjugated dienes include:
[0084] (a) Straight chain acyclic dienes such as 1,4-hexadiene;
1,5-heptadiene;
[0085] and 1,6-octadiene; [0086] (b) Branched chain acyclic dienes
such as 5-methyl-1,4-hexadiene; 3,7-dimethyl-1,6-octadiene; and
3,7-dimethyl-1,7-octadiene; [0087] (c) Single ring alicyclic dienes
such as 4-vinylcyclohexene; 1-allyl-4-isopropylidene cyclohexane;
3-allylcyclopentene; 4-allylcyclohexene; and
1-isopropenyl-4-butenylcyclohexene; [0088] (d) Multi-ring alicyclic
fused and bridged ring dienes such as dicyclopentadiene; alkenyl,
alkylidene, cycloalkenyl, and cycloalkylidene norbornenes, such as
5-methylene-2-norbornene; 5-methylene-6-methyl-2-norbornene;
5-methylene-6,6-dimethyl-2-norbornene; 5-propenyl-2-norbornene;
5-(3-cyclopentenyl)-2-norbornene; 5-ethylidene-2-norbornene; and
5-cyclohexylidene-2-norbornene.
[0089] One preferred conjugated diene is piperylene. The preferred
dienes are selected from the group consisting of 1,4-hexadiene;
dicyclopentadiene; 5-ethylidene-2-norbornene;
5-methylene-2-norbornene; 7-methyl-1,6 octadiene; piperylene; and
4-vinylcyclohexene.
[0090] The molecular weight of the ethylene/.alpha.-olefin
interpolymer will be selected on the basis of the desired
performance attributes of the adhesive formulation. Typically,
however, the ethylene/.alpha.-olefin interpolymer will preferably
have a number average molecular weight of at least 3,000,
preferably at least 5,000. Typically, the ethylene/.alpha.-olefin
interpolymer will preferably have a number average molecular weight
of no more than 100,000, more preferably no more than 60,000, and
even more preferably less than 40,000.
[0091] When the ethylene/.alpha.-olefin interpolymer has an
ultra-low molecular weight, and the like, a number average
molecular weight less than 11,000, the ethylene/.alpha.-olefin
interpolymer leads to a low polymer and formulation viscosity but
is characterized by a peak crystallization temperature which is
greater than that of corresponding higher molecular weight
materials of the same density. In pressure sensitive adhesive
applications, the increase in peak crystallization temperature
translates to an increased heat resistance. Ultra-low molecular
weight ethylene/.alpha.-olefin interpolymers are more fully
described below.
[0092] The density of the ethylene/.alpha.-olefin interpolymer will
likewise be selected on the basis of the desired performance
attributes of the adhesive formulation. Typically, however, the
ethylene/.alpha.-olefin interpolymer will have a density of at
least 0.850 g/cm.sup.3, preferably at least 0.860, and more
preferably at least 0.870 g/cm.sup.3. Typically, the
ethylene/.alpha.-olefin interpolymer will have a density of no more
than 0.965 g/cm.sup.3, preferably no more than 0.900 g/cm.sup.3,
more preferably no more than 0.890 g/cm.sup.3, and even more
preferably no more than 0.880 g/cm.sup.3, and most preferably no
more than 0.875 g/cm.sup.3.
[0093] The ethylene/.alpha.-olefin interpolymer will be present in
the adhesives of the invention in an amount greater than 5, and
preferably greater than 10 weight percent. The
ethylene/.alpha.-olefin interpolymer will typically be present in
the adhesive of the invention in an amount of not more than 95,
preferably not more than 80, and more preferably not more than 70
weight percent.
[0094] The adhesive may comprise a single homogeneous
ethylene/.alpha.-olefin interpolymer. In such an embodiment, the
homogeneous ethylene/.alpha.-olefin interpolymer will preferably
have a density ranging from 0.865 g/cm.sup.3 to 0.885 g/cm.sup.3.
When it is desired to prepare an adhesive formulation with a
minimal concentration of the homogeneous linear or substantially
linear interpolymer, and the like, adhesive formulations containing
less than 30 weight percent, preferably less than 25 weight percent
of the homogeneous ethylene/.alpha.-olefin interpolymer, the melt
index (I.sub.2 at 190.degree. C.) of the homogeneous linear or
substantially linear interpolymer will be preferably 50 or less,
more preferably 30 or less, and most preferably less than 10 g/10
min. It is is believed that adhesive compositions comprising as
little as 5 weight percent of the homogeneous
ethylene/.alpha.-olefin interpolymer having a melt index less than
0.5 g/10 min. would yield an advantageous performance.
[0095] In the case of pressure sensitive adhesives, preferred
adhesives will comprise from 5 to 45 weight percent, preferably
from 10 to 30, more preferably from 15 to 25 weight percent of a
single homogeneous ethylene/alpha-olefin interpolymer. For other
applications, for example packaging, the homogeneous linear or
substantially linear interpolymer will preferably be employed at
concentrations greater than 30 weight percent and have a melt index
of 500 g/10 min or less.
[0096] In another embodiment, the first homogeneous
ethylene/.alpha.-olefin interpolymer may be blended with a second
homogeneous ethylene/.alpha.-olefin interpolymer, wherein the first
and second interpolymers differ in number average molecular weight
by at least 5000, preferably at least 10,000, and more preferably
at least 20,000. In this embodiment, the combination of the lower
molecular weight and higher molecular weight components will tend
to yield an intermediate storage modulus at 25.degree. C. and an
improved probe tack.
[0097] In addition or in the alternative, the first homogeneous
ethylene/.alpha.-olefin interpolymer may be blended with a second
homogeneous ethylene/.alpha.-olefin interpolymer, wherein the first
and second interpolymers differ in density by at least 0.005
g/cm.sup.3, preferably by at least 0.01 g/cm.sup.3. In this
embodiment, particularly in the case of pressure sensitive
adhesives, as the density differential increases, the relative
proportion of the higher density interpolymer will typically
decrease, as the increased levels of crystallinity would otherwise
tend to decrease storage modulus at 25.degree. C. and probe tack to
levels which would render them unsuitable for use as pressure
sensitive adhesives.
[0098] In one preferred embodiment, the adhesive will comprise a
blend of two homogeneous ethylene/.alpha.-olefin, wherein the first
interpolymer having a density of 0.870 g/cm.sup.3 or less and the
second interpolymer having density greater than 0.900 g/cm.sup.3.
When high cohesive strength is desired, the first and second
homogeneous linear or substantially linear interpolymer, will
preferably both have relatively low melt indices, and the like, an
I.sub.2 of less than 30 g/10 min. In contrast, for lower viscosity
adhesive compositions, especially those which are sprayable at
temperatures less than 325.degree. F. (163.degree. C.), the second
homogeneous ethylene/.alpha.-olefin interpolymer will have a
greater density than the first homogeneous ethylene/.alpha.-olefin
interpolymer, and will preferably have a melt index greater than
125, more preferably greater than 500, and most preferably greater
than 1000 g/10 min.
[0099] Homogeneously branched linear ethylene/.alpha.-olefin
interpolymers may be prepared using polymerization processes (for
example, as described by Elston in U.S. Pat. No. 3,645,992) which
provide a homogeneous short chain branching distribution. In his
polymerization process, Elston uses soluble vanadium catalyst
systems to make such polymers. However, others such as Mitsui
Petrochemical Company and Exxon Chemical Company have used
so-called single site catalyst systems to make polymers having a
homogeneous linear structure. U.S. Pat. No. 4,937,299 to Ewen et
al. and U.S. Pat. No. 5,218,071, to Tsutsui et al. disclose the use
of catalyst systems based on hafnium for the preparation of
homogeneous linear ethylene polymers. Homogeneous linear
ethylene/.alpha.-olefin interpolymers are currently available from
Mitsui Petrochemical Company under the trade name "Tafmer" and from
Exxon Chemical Company under the trade name "Exact".
[0100] Substantially linear ethylene/.alpha.-olefin interpolymers
are available from The Dow Chemical Company as Affinity.TM.
polyolefin plastomers and Engage.TM. polyolefin elastomers.
Substantially linear ethylene/.alpha.-olefin interpolymers may be
prepared in accordance with the techniques described in U.S. Pat.
No. 5,272,236 and in U.S. Pat. No. 5,278,272.
[0101] Ultra-low molecular weight polymers may be made in
accordance with the Examples herein and with the procedures set
forth below.
[0102] The first polymer may be suitably prepared using a
constrained geometry metal complex, such as are disclosed in U.S.
application Ser. No. 545,403, filed Jul. 3, 1990 (EP-A-416,815);
U.S. application Ser. No. 702,475, filed May 20, 1991
(EP-A-514,828); as well as U.S. Pat. Nos. 5,470,993, 5,374,696,
5,231,106, 5,055,438, 5,057,475, 5,096,867, 5,064,802, and
5,132,380. In U.S. Ser. No. 720,041, filed Jun. 24, 1991,
(EP-A-514,828) certain borane derivatives of the foregoing
constrained geometry catalysts are disclosed and a method for their
preparation taught and claimed. In U.S. Pat. No. 5,453,410
combinations of cationic constrained geometry catalysts with an
alumoxane were disclosed as suitable olefin polymerization
catalysts.
[0103] Suitable activating cocatalysts and activating techniques
have been previously taught with respect to different metal
complexes in the following references: EP-A-277,003, U.S. Pat. No.
5,153,157, U.S. Pat. No. 5,064,802, EP-A468,651 (equivalent to U.S.
Ser. No. 07/547,718), EP-A-520,732 (equivalent to U.S. Ser. No.
07/876,268), WO 95/00683 (equivalent to U.S. Ser. No. 08/82,201),
and EP-A-520,732 (equivalent to U.S. Ser. No. 07/884,966 filed May
1, 1992.
[0104] Catalysts found to be particularly suitable in the
preparation of substantially linear ethylene/.alpha.-olefin
interpolymers include, for instance, the catalysts described in the
Examples set forth below, as activated by
trispentafluorophenylborane and triisobutylaluminum modified
methylalumoxane cocatalysts.
[0105] The molar ratio of metal complex: activating cocatalyst
employed preferably ranges from 1:1000 to 2:1, more preferably from
1:5 to 1.5:1, most preferably from 1:2 to 1:1. In the preferred
case in which a metal complex is activated by
trispentafluorophenylborane and triisobutylaluminum modified
methylalumoxane, the titanium:boron:aluminum molar ratio is
typically from 1:10:50 to 1:0.5:0.1, most typically from about
1:3:5.
[0106] A support, especially silica, alumina, or a polymer
(especially poly(tetrafluoroethylene) or a polyolefin) may be
employed, and desirably is employed when the catalysts are used in
a gas phase polymerization process. The support is preferably
employed in an amount to provide a weight ratio of catalyst (based
on metal) :support from 1:100,000 to 1:10, more preferably from
1:50,000 to 1:20, and most preferably from 1:10,000 to 1:30. In
most polymerization reactions the molar ratio of
catalyst:polymerizable compounds employed is from 10.sup.-12:1 to
10.sup.-1:1, more preferably from 10.sup.-9:1 to 10.sup.-5:1.
[0107] At all times, the individual ingredients as well as the
recovered catalyst components must be protected from oxygen and
moisture. Therefore, the catalyst components and catalysts must be
prepared and recovered in an oxygen and moisture free atmosphere.
Preferably, therefore, the reactions are performed in the presence
of a dry, inert gas such as, for example, nitrogen.
[0108] The polymerization may be carried out as a batchwise or a
continuous polymerization process, with continuous polymerizations
processes being required for the preparation of substantially
linear polymers. In a continuous process, ethylene, comonomer, and
optionally solvent and diene are continuously supplied to the
reaction zone and polymer product continuously removed
therefrom.
[0109] In general, the first polymer may be polymerized at
conditions for Ziegler-Natta or Kaminsky-Sinn type polymerization
reactions, that is, reactor pressures ranging from atmospheric to
3500 atmospheres. The reactor temperature should be greater than
80.degree. C., typically from 100.degree. C. to 250.degree. C., and
preferably from 100.degree. C. to 150.degree. C., with temperatures
at the higher end of the range, and the like, temperatures greater
than 100.degree. C. favoring the formation of lower molecular
weight polymers.
[0110] In conjunction with the reactor temperature, the
hydrogen:ethylene molar ratio influences the molecular weight of
the polymer, with greater hydrogen levels leading to lower
molecular weight polymers. When the desired polymer has an I.sub.2
of 1 g/10 min, the hydrogen:ethylene molar ratio will typically be
0:1. When the desired polymer has an I.sub.2 of 1000 g/10 min., the
hydrogen:ethylene molar ratio will typically be from 0.45:1 to
0.7:1. The upper limit of the hydrogen:ethylene molar ratio is from
2.2 to 2.5:1.
[0111] Generally the polymerization process is carried out with a
differential pressure of ethylene of from 10 to 1000 psi (70 to
7000 kPa), most preferably from 40 to 60 psi (30 to 300 kPa). The
polymerization is generally conducted at a temperature of from 80
to 250.degree. C., preferably from 90 to 170.degree. C., and most
preferably from greater than 95.degree. C. to 140.degree. C.
[0112] In most polymerization reactions the molar ratio of
catalyst:polymerizable compounds employed is from 10.sup.-12:1 to
10.sup.-1:1, more preferably from 10.sup.-9:1 to 10.sup.-5:1.
Solution polymerization conditions utilize a solvent for the
respective components of the reaction. Preferred solvents include
mineral oils and the various hydrocarbons which are liquid at
reaction temperatures. Illustrative examples of useful solvents
include alkanes such as pentane, iso-pentane, hexane, heptane,
octane and nonane, as well as mixtures of alkanes including
kerosene and Isopar-E.TM., available from Exxon Chemicals Inc.;
cycloalkanes such as cyclopentane and cyclohexane; and aromatics
such as benzene, toluene, xylenes, ethylbenzene and
diethylbenzene.
[0113] The solvent will be present in an amount sufficient to
prevent phase separation in the reactor. As the solvent functions
to absorb heat, less solvent leads to a less adiabatic reactor. The
solvent:ethylene ratio (weight basis) will typically be from 2.5:1
to 12:1, beyond which point catalyst efficiency suffers. The most
typical solvent:ethylene ratio (weight basis) is in the range of
from 5:1 to 10:1.
[0114] The ethylene/.alpha.-olefin interpolymer may alternatively
be prepared in a gas phase polymerization process, using the
catalysts as described above as supported in an inert support, such
as silica. The ethylene/.alpha.-olefin interpolymer may further be
made in a slurry polymerization process, using the catalysts as
described above as supported in an inert support, such as silica.
As a practical limitation, slurry polymerizations take place in
liquid diluents in which the polymer product is substantially
insoluble. Preferably, the diluent for slurry polymerization is one
or more hydrocarbons with less than 5 carbon atoms. If desired,
saturated hydrocarbons such as ethane, propane or butane may be
used in whole or part as the diluent. Likewise the .alpha.-olefin
monomer or a mixture of different .alpha.-olefin monomers may be
used in whole or part as the diluent. Most preferably the diluent
comprises in at least major part the .alpha.-olefin monomer or
monomers to be polymerized.
Concerning the Presence of Modifying Polymers.
[0115] Depending on the intended end use for the adhesive, it is
often desirable to add at least one compatible polymer in addition
to the homogeneous ethylene/.alpha.-olefin interpolymer at
concentrations up to 25 percent by weight to increase the cohesive
strength, improve the sprayability, modify the open time, increase
the flexibility, etc. This modifying polymer may be any compatible
elastomer, such as a thermoplastic block copolymer, a polyamide, an
amorphous or crystalline polyolefin such as polypropylene,
polybutylene or polyethylene wherein M.sub.w is greater than 3000;
an ethylenic copolymer such as ethylene-vinyl acetate (EVA),
ethylene-methyl acrylate, or a mixture thereof. Surprisingly, the
homogeneous ethylene/.alpha.-olefin interpolymers are also
compatible with polyamides, resulting in plasticizer resistant
pressure sensitive adhesives. The modifying polymer will typically
be used in a relatively low concentration, so as not to detract
from the improved properties of the homogeneous
ethylene/.alpha.-olefin interpolymer. A preferred modifying polymer
for increasing the open time and heat resistance is a polybutene-1
copolymer such as Duraflex.TM. 8910 (Shell).
[0116] Interpolymers of ethylene are those polymers having at least
one comonomer selected from the group consisting of vinyl esters of
a saturated carboxylic acid wherein the acid moiety has up to 4
carbon atoms, unsaturated mono- or dicarboxylic acids of 3 to 5
carbon atoms, a salt of the unsaturated acid, esters of the
unsaturated acid derived from an alcohol having 1 to 8 carbon
atoms, and mixtures thereof. Terpolymers of ethylene and these
comonomers are also suitable. Ionomers, which are completely or
partially neutralized copolymers of ethylene and the acids
described above, are discussed in more detail in U.S. Pat. No.
3,264,272. In addition, terpolymers of ethylene/vinyl
acetate/carbon monoxide or ethylene/methyl acrylate/carbon monoxide
containing up to 15 weight percent carbon monoxide may also be
employed.
[0117] The ethylene to unsaturated caboxylic comonomer weight ratio
is preferably from 95:5 to 40:60, more preferably from 90:10 to
45:50, and even more preferably from 85:15 to 60:40. The melt index
(I.sub.2 at 190.degree. C.) of these modifying interpolymers of
ethylene may range from 0.1 to 150, preferably from 0.3 to 50, and
more preferably from 0.7 to 10 g/10 min. Physical properties,
principally elongation, are known to decline to lower levels when
the ethylene copolymer melt index is above 30 g/10 min.
[0118] Suitable ethylene/unsaturated carboxylic acid, salt and
ester interpolymers include ethylene/vinyl acetate (EVA) including,
but not limited to, the stabilized EVA described in U.S. Pat. No.
5,096,955, incorporated herein by reference; ethylene/acrylic acid
(EEA) and its ionomers; ethylene/methacrylic acid and its ionomers;
ethylene/methyl acrylate; ethylene/ethyl acrylate;
ethylene/isobutyl acrylate; ethylene/n-butyl acrylate;
ethylene/isobutyl acrylate/methacrylic acid and its ionomers;
ethylene/n-butyl acrylate/methacrylic acid and its ionomers;
ethylene/isobutyl acrylate/acrylic acid and its ionomers;
ethylene/n-butyl acrylate/acrylic acid and its ionomers;
ethylene/methyl methacrylate; ethylene/vinyl acetate/methacrylic
acid and its ionomers; ethylene/vinyl acetate/acrylic acid and its
ionomers; ethylene/vinyl acetate/carbon monoxide;
ethylene/methacrylate/carbon monoxide; ethylene/n-butyl
acrylate/carbon monoxide; ethylene/isobutyl acrylate/carbon
monoxide; ethylene/vinyl acetate/monoethyl maleate; and
ethylene/methyl acrylate/monoethyl maleate. Particularly suitable
copolymers are EVA; EAA; ethylene/methyl acrylate;
ethylene/isobutyl acrylate; and ethylene/methyl methacrylate
copolymers and mixtures thereof. Certain properties, such as
tensile elongation, are taught to be improved by certain
combinations of these ethylene interpolymers, as described in U.S.
Pat. No. 4,379,190. The procedures for making these ethylene
interpolymers are well known in the art and many are commercially
available.
Concerning the Tackifier.
[0119] As used herein, the term "tackifier" means any of the
compositions described below which are useful to impart tack to the
hot melt adhesive composition. ASTM D-1878-61T defines tack as "the
property of a material which enables it to form a bond of
measurable strength immediately on contact with another
surface".
[0120] The adhesive of the invention will comprise from 0 to 95
weight percent of a tackifying resin. Typically, and particularly
when it is desired to employ less than 30 weight percent of the
homogeneous ethylene/.alpha.-olefin interpolymer, the adhesives
will comprise from 10 to 75 weight percent, more typically from 20
to 60 weight percent tackifier.
[0121] In the alternative, in cases where it is desirable to employ
at least 30 weight percent of the homogeneous
ethylene/.alpha.-olefin interpolymer, the present invention
advantageously provides adhesive formulations which contain minimal
tackifier, and the like, less than 30 weight percent tackifier,
preferably less than 25 weight percent tackifier, more preferably
less than 20 weight percent tackifier, and most preferably less
than 15 weight percent tackifier. In such applications, the
homogeneous ethylene/.alpha.-olefin interpolymer will preferably be
provided as a blend with a second homogeneous
ethylene/.alpha.-olefin interpolymer. In such instances, adhesives
containing less than 10 weight percent tackifier, and even
adhesives having no tackifier, exhibit adequate tack.
[0122] In general terms, the tackifying resins useful in the
adhesives of the invention comprise resins derived from renewable
resources such as rosin derivatives including wood rosin, tall oil,
gum rosin; rosin esters, natural and synthetic terpenes, and
derivatives of such. Aliphatic, aromatic or mixed
aliphatic-aromatic petroleum based tackifiers are also useful in
the adhesives of this invention. Representative examples of useful
hydrocarbon resins includes alpha-methyl styrene resins, branched
and unbranched C.sub.5 resins, C.sub.9 resins, C.sub.10 resins, as
well as styrenic and hydrogenated modifications of such. Tackifying
resins range from being a liquid at 37.degree. C. to having a ring
and ball softening point of about 135.degree. C. Solid tackifying
resins with a softening point greater than about 100.degree. C.,
more preferably with a softening point greater than about
130.degree. C. are particularly useful to improve the cohesive
strength of the adhesives of the present invention, particularly
when only a single homogeneous ethylene/.alpha.-olefin interpolymer
is utilized.
[0123] For the adhesives of the invention, the preferred tackifying
resin is predominantly aliphatic. However, tackifying resins with
increasing aromatic character are also useful, particularly when a
second tackifier or mutually compatible plasticizer is
employed.
Concerning the Plasticizer.
[0124] A plasticizer is broadly defined as a typically organic
composition that can be added to thermoplastics, rubbers and other
resins to improve extrudability, flexibility, workability, or
stretchability. In preferred embodiments of the invention, the
plasticizer will be provided to the adhesive in amounts up to 90
weight percent, preferably less than 30 weight percent of the
adhesive. The plasticizer may be either a liquid or a solid at
ambient temperature. Exemplary liquid plasticizers include
hydrocarbon oils, polybutene, liquid tackifying resins, and liquid
elastomers. Plasticizer oils are primarily hydrocarbon oils which
are low in aromatic content and which are paraffinic or napthenic
in character. Plasticizer oils are preferably low in volatility,
transparent and have as little color and odor as possible. The use
of plasticizers in this invention also contemplates the use of
olefin oligomers, low molecular weight polymers, vegetable oils and
their derivatives and similar plasticizing liquids.
[0125] When a solid plasticizing agent is employed, it will
preferably have a softening point above 60.degree. C. It is
believed that by combining the homogeneous ethylene/.alpha.-olefin
interpolymer with a suitable tackifying resin and a solid
plasticizer such as a cyclohexane dimethanol dibenzoate
plasticizer, the resulting adhesive composition may be applied at
temperatures below 120.degree. C., preferably below 100.degree. C.
Although a 1,4-cyclohexane dimethanol dibenzoate compound
commercially available from Velsicol under the trade name
Benzoflex.TM. 352 is exemplified, any solid plasticizer that will
subsequently recrystallize in the compounded thermoplastic
composition is suitable. Other plasticizers that may be suitable
for this purpose are described in EP 0422 108 B1 and EP 0 410 412
B1, both assigned to H. B. Fuller Company.
Concerning Waxes.
[0126] Waxes may be usefully employed in the adhesive compositions
of the present invention, particularly when the adhesive
composition is intended to be relatively tack free upon cooling and
solidifying, such as for various packaging and bookbinding
applications as well as foam in place gaskets. Waxes are commonly
used to modify the viscosity and reduce tack at concentrations up
to 60 percent by weight, preferably less than about 25 percent by
weight. Waxes useful in the adhesives of the present invention
include paraffin waxes, microcrystalline waxes, Fischer-Tropsch,
polyethylene and by-products of polyethylene wherein M.sub.w is
less than 3000. More preferably, the concentration of wax is less
than 35 percent by weight for high melt point waxes. At wax
concentrations above 35 percent by weight, paraffin waxes are
typically used.
[0127] Also suitable are ultra-low molecular weight
ethylene/.alpha.-olefin interpolymers prepared using a constrained
geometry catalyst, and may be referred to as homogeneous waxes.
Such homogeneous waxes, as well as processes for preparing such
homogeneous waxes, are set forth in the Examples below. Homogeneous
waxes, in contrast to paraffinic waxes and crystalline ethylene
homopolymer or interpolymer waxes, will have a M.sub.w/M.sub.n of
from 1.5 to 2.5, preferably from 1.8 to 2.2.
[0128] Homogeneous waxes will be either ethylene homopolymers or
interpolymers of ethylene and a C.sub.3-C.sub.20 .alpha.-olefin.
The homogeneous wax will have a number average molecular weight
less than 6000, preferably less than 5000. Such homogeneous waxes
will typically have a number average molecular weight of at least
800, preferably at least 1300.
[0129] Homogeneous waxes lead to a low polymer and formulation
viscosity, but are characterized by peak crystallization
temperatures which are greater than the peak crystallization
temperatures of corresponding higher molecular weight materials of
the same density. In adhesive applications, the increase in peak
crystallization temperature translates to an increased beat
resistance, and the like, improved creep resistance in pressure
sensitive adhesives, and improved SAFT in hot melt adhesives.
Concerning the Presence of Other Additives.
[0130] As is known in the art, various other components can be
added to modify the tack, color, odor, etc., of a hot melt
adhesive. Additives such as antioxidants (for example, hindered
phenolics (for example, Irganox.TM. 1010, Irganox.TM. 1076),
phosphites (for example, Irgafos.TM. 168)), antiblock additives,
pigments, and fillers, can also be included in the formulations. It
is generally preferred that the additives should be relatively
inert and have negligible effects upon the properties contributed
by the homogeneous linear or substantially linear interpolymer,
tackifying agent, and plasticizing oil.
Rheological Performance of Adhesives as Pressure Sensitive
Adhesives.
[0131] As set forth in J. Class and S. Chu, Handbook of Pressure
Sensitive Adhesive Technology, Second Edition, D. Satas, 1989,
pages 158-204, the requirements for pressure sensitive adhesive
behavior may be defined by temperature and rate dependent
viscoelastic properties of the materials and formulations.
[0132] Broadly speaking, to be a suitable pressure sensitive
adhesive, the formulations must have a glass transition temperature
of from -45.degree. C. to 30.degree. C., preferably from
-20.degree. C. to 25.degree. C., as reflected by the tan .delta.
peak temperature at 1 radian per second, as determined by DMS.
[0133] According to what has come to be known as the Dahlquist
criteria, broadly speaking, to be a suitable pressure sensitive
adhesive, the formulation must have a plateau shear modulus at
25.degree. C. at 1 radian per second which is between
1.times.10.sup.5 and 4.times.10.sup.6 dynes/cm.sup.2 (0.01 to 0.4
MPa), preferably from 3.times.10.sup.5 and 1.times.10.sup.6
dynes/cm.sup.2 (0.03 to 0.1 MPa), as determined by DMS. A material
stiffer than this, and the like, a material which has a plateau
shear modulus at 25.degree. C. of 1.times.10.sup.7 dynes/cm.sup.2
(1 MPa), will not exhibit surface tack at room temperature. A
material less stiff than this, and the like, a material which has a
plateau shear modulus at 25.degree. C. of 1.times.10.sup.4
dynes/cm.sup.2 (0.001 MPa) will lack sufficient cohesive strength
to be useful.
[0134] The Dalquist criteria are useful to identify polymers which
will have utility in various pressure sensitive adhesive
applications. In particular, preferred pressure sensitive adhesives
for use in low peel labels will have a G' of from 3.times.10.sup.5
to 1.times.10.sup.6 dynes/cm.sup.2 (0.03 to 0.1 MPa) and a glass
transition temperature of from -50 to -30.degree. C. Preferred
pressure sensitive adhesives for use in freezer labels will have a
G' of from 8.times.10.sup.4 to 2.times.10.sup.5 dynes/cm.sup.2
(0.008 to 0.02 MPa) and a glass transition temperature of from -45
to -30.degree. C. Preferred pressure sensitive adhesives for use in
cold temperature labels will have a G' of from 2.times.10.sup.5 to
1.times.10.sup.6 dynes/cm.sup.2 (0.02 to 0.1 MPa) and a glass
transition temperature of from -25 to -10.degree. C. Preferred
pressure sensitive adhesives for use in pressure sensitive adhesive
tapes will have a G' of from 7.times.10.sup.5 to .times.10.sup.6
dynes/cm.sup.2 (0.07 to 0.5 MPa) and a glass transition temperature
of from -10 to 10.degree. C. Preferred pressure sensitive adhesives
for use in high peel labels will have a G' of from 2.times.10.sup.5
to 6.times.10.sup.6 dynes/cm.sup.2 (0.02 to 0.06 MPa) and a glass
transition temperature of from 0 to 10.degree. C. Preferred
pressure sensitive adhesives for use in disposables will have a G'
of from 4.times.10.sup.5 to 2.times.10.sup.6 dynes/cm.sup.2 (0.04
to 0.2 MPa) and a glass transition temperature of from 10 to
30.degree. C.
Formulations Useful for Hot Melt Adhesives
[0135] The follow Table A sets forth useful and preferred weight
percentages of various components of the adhesive formulations of
the invention, including formulations which will be preferred when
it is desirable to utilize less than 30 weight percent of the
homogeneous ethylene/.alpha.-olefin interpolymer: TABLE-US-00001
TABLE A Hot Melt Pressure Sensitive Adhesives Adhesives Useful
Preferred Useful Preferred Homogeneous ethylene/ 5-95 5-30 5-95
10-30 .alpha.-olefin interpolymer Tackifier 0-95 20-60 0-95 20-60
Plasticizer (Oil) 0 0 0-95 0-30 Plasticizer (Solid) <30 10-20
0-50 10-50 Wax 0-60 5-25 <10 percent <5 percent
Processes for the Preparation of Hot Melt Adhesives.
[0136] The hot melt adhesives and pressure sensitive adhesives of
the invention may be prepared by standard melt blending procedures.
In particular, the first polymer(s), tackifier(s), and optional
plasticizer(s) may be melt blended at an elevated temperature (from
150 to 200.degree. C.) under an inert gas blanket until a
homogeneous mix is obtained. Any mixing method producing a
homogeneous blend without degrading the hot melt components is
satisfactory, such as through the use of a heated vessel equipped
with a stirrer.
[0137] Further, the homogeneous ethylene/.alpha.-olefin
interpolymer(s), optional tackifier(s) and optional plasticizer(s)
may be provided to an extrusion coater for application to the
substrate.
[0138] When the ethylene/.alpha.-olefin interpolymer is a blend of
two or more ethylene/.alpha.-olefin interpolymers, it will be
preferred to prepare the pressure sensitive adhesives using a dual
reactor configuration, with one of the polymers being produced in
the first reactor, the other of the polymers being produced in a
second reactor, and the tackifier(s) and optional plasticizer(s)
being optionally provided, typically at a point after the second
reactor, via a side-arm extruder. In this embodiment, pressure
sensitive adhesives can be provided in forms such as pellets,
pillows, or any other desired configuration. Examples of such a
process which may be adapted in accordance with the teachings of
this disclosure to prepare blends of a homogenous linear (higher
molecular weight or ultra-low molecular weight) or substantially
linear ethylene/.alpha.-olefin interpolymer, wax, and optional
tackifier, are disclosed in WO 94/00500 and WO 94/01052.
[0139] The hot melt adhesives of the present invention can be
applied by extrusion, spiral spray, meltblown, spray-splatter,
screen printing, or roll coating by delivery from bulk or
reservoirs capable of controlling the temperature within a range
from about 250.degree. F. to about 400.degree. F. Packaging and
bookbinding applications, particularly for adhesives which are
relatively tack-free upon cooling are specifically within the scope
of the present invention. However, any adhesive application
pertaining to bonding a paper substrate selected from the group
consisting of Kraft paper, coated paper, highly filled paper,
laminated paper, etc. to any other paper substrate and/or polymeric
film substrate is also contemplated, especially when applied by
extrusion or lamination by roll coaters.
Test Methods
[0140] Unless indicated otherwise, the following testing procedures
are employed:
[0141] Density is measured in accordance with ASTM D-792. The
samples are annealed at ambient conditions for 24 hours before the
measurement is taken.
[0142] Melt index (I.sub.2), is measured in accordance with ASTM
D-1238, condition 190.degree. C./2.16 kg (formally known as
"Condition (E)").
[0143] Molecular weight is determined using gel permeation
chromatography (GPC) on a Waters 150.degree. C. high temperature
chromatographic unit equipped with three mixed porosity columns
(Polymer Laboratories 103, 104, 105, and 106), operating at a
system temperature of 140.degree. C. The solvent is
1,2,4-trichlorobenzene, from which 0.3 percent by weight solutions
of the samples are prepared for injection. The flow rate is 1.0
mL/min and the injection size is 100 microliters.
[0144] The molecular weight determination is deduced by using
narrow molecular weight distribution polystyrene standards (from
Polymer Laboratories) in conjunction with their elution volumes.
The equivalent polyethylene molecular weights are determined by
using appropriate Mark-Houwink coefficients for polyethylene and
polystyrene (as described by Williams and Word in Journal of
Polymer Science, Polymer Letters, Vol. 6, (621) 1968, incorporated
herein by reference) to derive the following equation:
M.sub.polyethylene=a*(M.sub.polystyrene)b.
[0145] In this equation, a=0.4316 and b=1.0. Weight average
molecular weight, M.sub.w, is calculated in the usual manner
according to the following formula: M.sub.w=.SIGMA.w.sub.i*M.sub.i,
where w.sub.i and M.sub.i are the weight fraction and molecular
weight, respectively, of the ith fraction eluting from the GPC
column. TABLE-US-00002 Fineline & Spray Adjust the hot melt
applicator and laminator to proper setting. Nip Pressure 15 psi
(0.1 MPa) Spiral Spray 4 mg/in.sup.2 (26 mg/cm.sup.2) Fineline 1.4
mg/in (3.6 mg/cm) Web Speed 400-500 ft/min (120-150 meters/min) Air
Temp. 50.degree. F. (10.degree. C.) above application temp Nozzle
Distance from Substrate 30-60 mm
[0146] Prepare fineline and spray bonds using the settings
indicated above. During the run, drop eight to ten 2 inch by 8 inch
(5 cm by 20 cm) strips of release paper cross directional across
the web to serve as starting points for the T-peel evaluation. Cut
10 samples one bead or one spray spiral in width by 3 inches (7.6
cm) in length. Run T-peels on a slip/peel tester, Instron or other
suitable measuring device at 12 inches (30 cm) per minute Report
the average of 10 samples.
T-Peels
[0147] This test method describes how to measure the removal force
of an adhesive surface bonded to a fabric substrate.
Material and Equipment:
[0148] 1. Mechanical roll-down device with 4.5 pound (2 kg) roller.
Available through: Engineering Service, Glenview Ill. 60025 [0149]
2. Slip Peel Tester Available though: Instrumentors, Inc.,
Cleveland, Ohio 44136
[0150] The first step is to prepare hot melt coated adhesive films
on Mylar or polyolefin film using a suitable coating device at an
appropriate application temperature. During preparation of the
adhesive film, the adhesive surface is covered with release paper
to facilitate handling. The coat weight is checked targeting 25
g/m.sup.2+/-3 g/m.sup.2.
[0151] The adhesive coated films are cut into 1 inch (2.5 cm) wide
strips which are 4 inches (10 cm) in length in the machine
direction. At one end of each strip, fold approximately 1/4 inch
(0.6 cm) of the strip onto itself to create a grip. Remove the
release paper and place the adhesive surface of one 1 inch (2.5 cm)
wide strip onto knit cotton test kit to form a composite. Place the
composite on the mechanical roll-down device, and allow the roller
two passes over the sample; one forward and one back. A timer is
activated and the sample is placed into the jaws of the slip-peel
tester. The 1 inch (2.5 cm) wide strip is placed into the mobile
jaw and the fabric is placed in the stationary jaw. No more than 1
minute after the sample has been removed from the roll-down device,
the sample is peeled at 12 inches per minute (30 cm/min), averaging
over 10 seconds. The procedure is repeated five times, recording
the average T-peel value and noting any legging or transfer. The
T-peel values are reported in grams per linear inch. In the
disposable article industry, it is preferred to have T-peels in the
100-500 g range, most preferred in the 200-500 g range without
adhesive transfer.
Oil Exudation
[0152] Approximately 20 g of the adhesive is poured onto release
paper. (Akrosil F1U-F4B Silox, 40-60#) After cooling for about 4
hours, the adhesive is evaluated for oil exudation. "Pass"
indicates that the adhesive is removable from the release paper
without visibly staining the release paper.
PAFT & SAFT
[0153] Each adhesive sample was coated onto Kraft paper by hand
using glass rods or shims. The resultant coating is a 1 inch (2.5
cm) wide band that is about 8-10 mils or 0.008 to 0.010 inches 0.2
to 0.25 mm) thick. After conditioning the bonds at room temperature
for at least 16 hours, the peel adhesion failure temperature (PAFT)
and shear adhesion failure temperature (SAFT) were determined by
placing samples in a programmed oven with 100 gram weights for the
peel mode and 500 gram weights for the shear mode, ramping the
temperature up from 25.degree. C. to 175.degree. C. at a rate of
25.degree. C./hour. The oven automatically records the temperature
at which the samples fail. The reported result is the average
failure temperature of four to five bonds.
Bonding Tests
[0154] Adhesive bonds were made on various substrates using an
application temperature of about 175.degree. C., an open time of
about 1 second, a set time of about 1 second, and a bead size
ranging from 1/16 inch (2.5 mm) to 1/8 inch (3.1 mm). The resulting
bonds were then conditioned for at least 24 hours, separated by
hand and the amount of fiber tear determined. A minimum of three
samples were tested for each adhesive at each condition reporting
the average fiber tear.
Cloud Point
[0155] A 25 mm.times.150 mm Pyrex test tube is filled 3/4 full with
molten hot melt adhesive at a temperature of about 177.degree. C. A
thermometer is inserted into the molten hot melt resting against
the test tube wall. The "cloud point" is the temperature at which
the thermometer markings are no longer visible when observed
through the test tube wall opposite the thermometer.
Ultimate Tensile & Elongation
[0156] Prepare a 20-30 mil (0.5-0.7 mm) thick adhesive film free of
air bubbles on a polytetrafluoroethylene or aluminum sheet. Cut 7
dogbones lengthwise from the film measuring the thickness at the
gauge section. Condition the samples for at least 24 hours at
21.degree. C. and 23 to 50 percent relative humidity. Place each
sample in the jaws of an Instron tensile tester or equivalent with
a load cell capable of measuring a 4 pounds (1.8 kg) force+/-1
percent. Elongate samples at a 10 inches/minute (20.5 cm/min)
crosshead speed until break. Record the "Ultimate Tensile" at yield
by dividing the maximum force by the cross-section area of the
sample and "percent Elongation" by dividing the displacement at
break by the sample length and multiply by 100. The "Ultimate
Tensile" and "percent Elongation" are an average of at least five
samples.
Cold Crack
[0157] Prepare several 1 inch by 3 inch (2.5 cm by 7.6 cm) adhesive
films free of air bubbles which are 20-30 mils (0.5-0.7 nun) in
thickness. Place three films individually over the v-shaped base of
a cold crack apparatus which consists of a stand with an
interlocking pressure bar. The stand is 3 inches (7.6 cm) by 0.75
inch (1.9 cm) wide and 12 inches (30 cm) long. A 90.degree. angle
is cut squarely 1/2 inch (1.3 cm) deep into the top surface. Place
the pressure bar, which is also cut at a 90.degree. angle, into the
gap of the stand. This test is repeated lowering the temperature at
5.degree. F. (3.degree. C.) increments with a new film sample for
each temperature until the film cracks. The recorded "Cold Crack"
is an average of at least 2 samples.
Melt Viscosity
[0158] Melt viscosity is determined in accordance with the
following procedure using a Brookfield Laboratories
DVII++Viscometer in disposable aluminum sample chambers. The
spindle used is a SC-31 hot-melt spindle, suitable for measuring
viscosities in the range of from 10 to 100,000 centipoise. A
cutting blade is employed to cut samples into pieces small enough
to fit into the 1 inch (2.5 cm) wide and 5 inches (13 cm) long
sample chamber. The sample is placed in the chamber, which is in
turn inserted into a Brookfield Thermosel and locked into place
with bent needle-nose pliers. The sample chamber has a notch on the
bottom that fits the bottom of the Brookfield Thermosel to ensure
that the chamber is not allowed to turn when the spindle is
inserted and spinning. The sample is heated to 350.degree. F.
(177.degree. C.), with additional sample being added until the
melted sample is about 1 inch (2.5 cm) below the top of the sample
chamber. The viscometer apparatus is lowered and the spindle
submerged into the sample chamber.
[0159] Lowering is continued until brackets on the viscometer align
on the Thermosel. The viscometer is turned on, and set to a shear
rate which leads to a torque reading in the range of 30 to 60
percent. Readings are taken every minute for about 15 minutes, or
until the values stabilize, which final reading is recorded.
G', G'', and Peak Tan Delta
[0160] G', G'', and peak tan delta, are determined as follows. The
samples are examined using melt rheology techniques on a
Rheometrics RDA-II Dynamic Analyzer. The Temperature-Step mode is
used utilizing the 7.9 mm diameter parallel plates geometry. The
sweep is run from approximately -70.degree. C. to 250.degree. C. at
5.degree. C. per step with 30 seconds equilibration delay at each
step. The oscillatory frequency is 1 radian/second with an
autostrain functions of 0.1 percent strain initially, increasing in
positive 100 percent adjustments when ever the torque decreased to
10 gram-centimeters. The maximum strain is set at 26 percent. The
autotension function is used in the compression direction with a
force of -3, sensitivity at 15, and switching occurring at 100
dynes/cm.sup.2 (10 Pa). The plates are used with an initial gap of
1.5 mm at 160.degree. C. (the sample aliquots are inserted in the
RDS-II at 160.degree. C.). The "HOLD" function is engaged at
160.degree. C. and the instrument was cooled to -70.degree. C. and
the test started (the "HOLD") function corrects for the thermal
expansion or contraction of the test chamber is heated or cooled).
The Samples are maintained in a nitrogen environment throughout the
analyses to minimize oxidative degradation. Data reduction and
manipulation are accomplished by the Rheometrics, Inc. RHIOS
computer programs (version 4.4.0). The computer software plots G'
(the dynamic storage modulus of the sample), G'' (the dynamic loss
modulus of the sample), tan delta (G'/G''), and peak tan delta (a
representation of the glass transition temperature).
Probe Tack
[0161] Probe tack is determined in accordance with ASTM D-2979-71,
using a dwell time of 10 seconds and a probe separation rate of 1
cm/sec. TABLE-US-00003 TABLE OF CONTENTS FOR THE EXAMPLES I. Hot
Melt Adhesive Examples Catalyst Preparation Polymerization of
ultra-low molecular weights polymers and waxes. Table One -
Polymers A-D and Waxes 1-3 Polymerization Conditions. Table Two -
Polymers E-F and Wax 4 Polymerization Conditions. Hot Melt Adhesive
Examples Table Three - Examples HMA-1 to HMA-9 Table Four -
Examples HMA-10 to HMA-15 Table Five - Examples HMA-16 to HMA-24
Examples 25 and 26 II. Hot Melt Pressure Sensitive Adhesive
Examples Preparation of Adhesives Table Six - Examples PSA-27 TO
PSA-32 Table Seven - Examples PSA-33 to PSA-34 III. Application
Specific Adhesive Examples Tables Eight and Eight-A - Interpolymers
and Formulation Components Table Nine - Nonwoven Construction
Adhesives Table Ten - Nonwoven Construction Bonding Results Table
Eleven - Thermal Stability of Adhesives Table Twelve - Positioning
Adhesives Table Thirteen - Additional PSA Examples Table Fourteen -
Additional Interpolymer/EVA Blends Table Fifteen - Target
Bookbinding Properties Tables Sixteen A and B- Bookbinding Table
Seventeen- Case and Carton Seal Tables Eighteen A, B, C - Packaging
Adhesives Tables Nineteen A to E - Interpolymer/Oil Blends Tables
Twenty A and B- Interpolymer/Polyamide Blends Table Twenty-One -
Insulation Bonding I. Hot Melt Adhesive Examples
Catalyst Preparation One
Part 1: Preparation of TiCl.sub.3(DME).sub.1.5
[0162] The apparatus (referred to as R-1) was set-up in the hood
and purged with nitrogen; it consisted of a 10 L glass kettle with
flush mounted bottom valve, 5-neck head, polytetrafluoroethylene
gasket, clamp, and stirrer components (bearing, shaft, and paddle).
The necks were equipped as follows: stirrer components were put on
the center neck, and the outer necks had a reflux condenser topped
with gas inlet/outlet, an inlet for solvent, a thermocouple, and a
stopper. Dry, deoxygenated dimethoxyethane (DME) was added to the
flask (approx. 5 L). In the drybox, 700 g of TiCl.sub.3 was weighed
into an equalizing powder addition funnel; the funnel was capped,
removed from the drybox, and put on the reaction kettle in place of
the stopper. The TiCl.sub.3 was added over about 10 minutes with
stirring. After the addition was completed, additional DME was used
to wash the rest of the TiCl.sub.3 into the flask. The addition
funnel was replaced with a stopper, and the mixture heated to
reflux. The color changed from purple to pale blue. The mixture was
heated for about 5 hours, cooled to room temperature, the solid was
allowed to settle, and the supernatant was decanted from the solid.
The TiCl.sub.3(DME).sub.1.5 was left in R-1 as a pale blue
solid.
Part 2: Preparation of
[Me.sub.4C.sub.5)SiMe.sub.2N-t-Bu][MpCl].sub.2
[0163] The apparatus (referred to as R-2) was set-up as described
for R-1, except that flask size was 30 L. The head was equipped
with seven necks; stirrer in the center neck, and the outer necks
containing condenser topped with nitrogen inlet/outlet, vacuum
adapter, reagent addition tube, thermocouple, and stoppers. The
flask was loaded with 4.5 L of toluene, 1.14 kg of
(Me.sub.4C.sub.5H)SiMe.sub.2NH-t-Bu, and 3.46 kg of 2 M i-PrMgCl in
Et.sub.2O. The mixture was then heated, and the ether allowed to
boil off into a trap cooled to -78.degree. C. After four hours, the
temperature of the mixture had reached 75.degree. C. At the end of
this time, the heater was turned off and DME was added to the hot,
stirring solution, resulting in the formation of a white solid. The
solution was allowed to cool to room temperature, the material was
allowed to settle, and the supernatant was decanted from the solid.
The [(Me.sub.4C.sub.5)SiMe.sub.2N-t-Bu][MgCl].sub.2 was left in R-2
as an off-white solid.
Part 3: Preparation of
[(.eta..sup.5-Me.sub.4C.sub.5)SiMe.sub.2N-t-Bu]TiMe.sub.2
[0164] The materials in R-1 and R-2 were slurried in DME (3 L of
DME in R-1 and 5 L in R-2). The contents of R-1 were transferred to
R-2 using a transfer tube connected to the bottom valve of the 10 L
flask and one of the head openings in the 30 L flask. The remaining
material in R-1 was washed over using additional DME. The mixture
darkened quickly to a deep red/brown color, and the temperature in
R-2 rose from 21.degree. C. to 32.degree. C. After 20 minutes, 160
mL of CH.sub.2Cl.sub.2 was added through a dropping funnel,
resulting in a color change to green/brown. This was followed by
the addition of 3.46 kg of 3 M MeMgCl in THF, which caused a
temperature increase from 22.degree. C. to 5.degree. C. The mixture
was stirred for 30 minutes, then 6 L of solvent was removed under
vacuum. Isopar.TM. E hydrocarbon (6 L) was added to the flask. This
vacuum/solvent addition cycle was repeated, with 4 L of solvent
removed and 5 L of Isopar.TM. E hydrocarbon added. In the final
vacuum step, an additional 1.2 L of solvent was removed. The
material was allowed to settle overnight, then the liquid layer
decanted into another 30 L glass kettle (R-3). The solvent in R-3
was removed under vacuum to leave a brown solid, which was
re-extracted with Isopar E; this material was transferred into a
storage cylinder. Analysis indicated that the solution (17.23 L)
was 0.1534 M in titanium; this is equal to 2.644 moles of
[(.eta..sup.5-Me.sub.4C.sub.5)SiMe.sub.2N-t-Bu]TiMe.sub.2. The
remaining solids in R-2 were further extracted with Isopar.TM. E
hydrocarbon, the solution was transferred to R-3, then dried under
vacuum and re-extracted with Isopar.TM. E hydrocarbon. This
solution was transferred to storage bottles; analysis indicated a
concentration of 0.1403 M titanium and a volume of 4.3 L (0.6032
moles [(.eta..sup.5-Me.sub.4C.sub.5)SiMe.sub.2N-t-Bu]TiMe.sub.2).
This gives an overall yield of 3.2469 moles of
[(.eta..sup.5-Me.sub.4C.sub.5)SiMe.sub.2N-t-Bu]TiMe.sub.2, or 1063
g. This is a 72 percent yield overall based on the titanium added
as TiCl.sub.3.
Catalyst Preparation Two
Part 1: Preparation of TiCl.sub.3(DME).sub.1.5
[0165] The apparatus (referred to as R-1) was set-up in the hood
and purged with nitrogen; it consisted of a 10 L glass kettle with
flush mounted bottom valve, 5-neck head, polytetrafluorethylene
gasket, clamp, and stirrer components (bearing, shaft, and paddle).
The necks were equipped as follows: stirrer components were put on
the center neck, and the outer necks had a reflux condenser topped
with gas inlet/outlet, an inlet for solvent, a thermocouple, and a
stopper. Dry, deoxygenated dimethoxyethane (DME) was added to the
flask (approx. 5.2 L). In the drybox, 300 g of TiCl.sub.3 was
weighed into an equalizing powder addition funnel; the funnel was
capped, removed from the drybox, and put on the reaction kettle in
place of the stopper. The TiCl.sub.3 was added over about 10
minutes with stirring. After the addition was completed, additional
DME was used to wash the rest of the TiCl.sub.3 into the flask.
This process was then repeated with 325 g of additional TiCl.sub.3,
giving a total of 625 g. The addition funnel was replaced with a
stopper, and the mixture heated to reflux. The color changed from
purple to pale blue. The mixture was heated for about 5 hours,
cooled to room temperature, the solid was allowed to settle, and
the supernatant was decanted from the solid. The
TiCl.sub.3(DME).sub.1.5 was left in R-1 as a pale blue solid.
Part 2: Preparation of
[(Me.sub.4C.sub.5)SiMe.sub.2-N-t-Bu][MgCl].sub.2
[0166] The apparatus (referred to as R-2) was set-up as described
for R-1, except that flask size was 30 L. The head was equipped
with seven necks; stirrer in the center neck, and the outer necks
containing condenser topped with nitrogen inlet/outlet, vacuum
adapter, reagent addition tube, thermocouple, and stoppers. The
flask was loaded with 7 L of toluene, 3.09 kg of 2.17 M i-PrMgCl in
Et.sub.2O, 250 mL of THF, and 1.03 kg of
(Me.sub.4C.sub.5H)SiMe.sub.2NH-t-Bu. The mixture was then heated,
and the ether allowed to boil off into a trap cooled to -78.degree.
C. After three hours, the temperature of the mixture had reached
80.degree. C., at which time a white precipitate formed. The
temperature was then increased to 90.degree. C. over 30 minutes and
held at this temperature for 2 hours. At the end of this time, the
heater was turned off, and 2 L of DME was added to the hot,
stirring solution, resulting in the formation of additional
precipitate. The solution was allowed to cool to room temperature,
the material was allowed to settle, and the supernatant was
decanted from the solid. An additional wash was done by adding
toluene, stirring for several minutes, allowing the solids to
settle, and decanting the toluene solution. The
[(Me.sub.4C.sub.5)SiMe.sub.2N-t-Bu][MgCl].sub.2 was left in R-2 as
an off-white solid.
Part 3: Preparation of
[(.eta.5-Me.sub.4C.sub.5)SiMe.sub.2N-t-Bu]Ti(.eta..sup.4-1,3-pentadiene)
[0167] The materials in R-1 and R-2 were slurried in DME (the total
volumes of the mixtures were approximately 5 L in R-1 and 12 L in
R-2). The contents of R-1 were transferred to R-2 using a transfer
tube connected to the bottom valve of the 10 L flask and one of the
head openings in the 30 L flask. The remaining material in R-1 was
washed over using additional DME. The mixture darkened quickly to a
deep red/brown color. After 15 minutes, 1050 mL of 1,3-pentadiene
and 2.60 kg of 2.03 M n-BuMgCl in THF were added simultaneously.
The maximum temperature reached in the flask during this addition
was 53.degree. C. The mixture was stirred for 2 hours, then
approximately 11 L of solvent was removed under vacuum. Hexane was
then added to the flask to a total volume of 22 L. The material was
allowed to settle, and the liquid layer (12 L) was decanted into
another 30 L glass kettle (R-3). An additional 15 liters of product
solution was collected by adding hexane to R-2, stirring for 50
minutes, again allowing to settle, and decanting. This material was
combined with the first extract in R-3. The solvent in R-3 was
removed under vacuum to leave a red/black solid, which was then
extracted with toluene. This material was transferred into a
storage cylinder. Analysis indicated that the solution (11.75 L)
was 0.255 M in titanium; this is equal to 3.0 moles of
[(.eta..sup.5-Me.sub.4C.sub.5)SiMe.sub.2N-t-Bu]Ti(.eta..sup.4-1,3-pentadi-
ene) or 1095 g. This is a 74 percent yield based on the titanium
added as TiCl.sub.3.
Polymerization of Ultra-Low Molecular Weight Polymers and Waxes
[0168] Polymers A-D and Waxes 1-3 were produced in a solution
polymerization process using a continuously stirred reactor.
Polymers A, B, and C, and Wax 1 were each stabilized with 1250 ppm
calcium stearate, 500 ppm Irganox.TM. 1076 hindered polyphenol
stabilizer (available from Ciba-Geigy Corporation), and 800 ppm
PEPQ (tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene
diphosphonite) (available from Clariant Corporation). Polymer D and
Waxes 2 and 3 were each stabilized with 500 ppm Irganox.TM. 1076
hindered polyphenol stabilizer, 800 ppm PEPQ, and 100 ppm water (as
a catalyst kill agent).
[0169] The ethylene and the hydrogen were combined into one stream
before being introduced into the diluent mixture, a mixture of
C.sub.8-C.sub.10 saturated hydrocarbons, for example, ISOPAR-E
hydrocarbon mixture (available from Exxon Chemical Company) and the
comonomer. For polymers A, B, C, and D and for Waxes 1 and 2 the
comonomer was 1-octene; Wax 3 had no comonomer. The reactor feed
mixture was continuously injected into the reactor.
[0170] The metal complex and cocatalysts were combined into a
single stream and were also continuously injected into the reactor.
For Polymers A, B, and C and Wax 1, the catalyst was as prepared in
Catalyst Preparation One set forth above. For Polymer D and Waxes 2
and 3, the catalyst was as prepared in Catalyst Preparation Two set
forth above. For each Polymer and Wax, the co-catalyst was
tris(pentafluorophenyl)borane, available as a 3 wt percent solution
in Isopar.TM.-E mixed hydrocarbon, from Boulder Scientific.
Aluminum was provided in the form of a solution of modified
methylalumoxane (MMAO Type 3A) in heptane, which is available at a
2 wt percent aluminum concentration from Akzo Nobel Chemical
Inc.
[0171] Sufficient residence time was allowed for the metal complex
and cocatalyst to react prior to introduction into the
polymerization reactor. In each polymerization reaction, the
reactor pressure was held constant at about 475 psig (3.3 MPa).
Ethylene content of the reactor, in each polymerization, after
reaching steady state, was maintained at the conditions specified
in Table One.
[0172] After polymerization, the reactor exit stream was introduced
into a separator where the molten polymer is separated from the
unreacted comonomer(s), unreacted ethylene, unreacted hydrogen, and
diluent mixture stream. The molten polymer was subsequently strand
chopped or pelletized, and, after being cooled in a water bath or
pelletizer, the solid pellets were collected. Table One describes
the polymerization conditions and the resultant polymer properties.
TABLE-US-00004 TABLE ONE Polymer A Polymer B Polymer C Polymer D
Wax 1 Wax 2 Wax 3 Ethylene feed (lb/hr (kg/hr)) 2.0 2.0 2.0 3.0 3.0
3.0 3.0 (0.9) (0.9) (0.9) (1.4) (1.4) (1.4) (1.4) Comonomer: olefin
ratio (mole percent) 12.40 8.50 12.50 9.10 0.40 1.24 0.00 Hydrogen:
ethylene ratio (mole percent) 0.26 0.66 1.26 0.54 1.60 2.14 2.14
Diluent: ethylene ratio (weight basis) 10.60 9.30 11.10 9.99 5.90
7.69 7.70 Catalyst metal concentration (ppm) 4 2 4 3 5 32 32
Catalyst flow rate (lb/hr (kg/hr)) 0.272 0.386 0.428 0.450 0.626
0.304 0.294 (0.123) (0.175) (0.194) (0.205) (0.285) (0.138) (0.134)
Co-catalyst concentration (ppm) 88 44 88 88 353 1430 1430
Co-catalyst flow rate (lb/hr (kg/hr)) 0.396 0.561 0.624 0.490 0.284
0.219 0.211 (0.180) (0.254) (0.283) (0.223) (0.129) (0.100) (0.096)
Aluminum concentration (ppm) 10 5 10 9.8 20 120.0 120.0 Aluminum
flow rate (lb/hr) 0.375 0.528 0.590 0.468 0.534 0.323 0.311 (0.170)
(0.240) (0.268) (0.213) (0.243) (0.147) (0.141) Reactor temperature
(.degree. C.) 110 110 110 110 140 110 110 Ethylene concentration in
reactor exit stream 1.80 2.99 1.65 1.71 4.41 1.80 1.69 (weight
percent) Polymer density (g/cm.sup.3) 0.875 0.897 0.870 0.883 0.968
0.948 0.960 Polymer melt viscosity at 350.degree. F. (centipoise)
39,000* 5200 355 5000 395 350 512 Polymer melt index (I.sub.2 at
190.degree. C.) 246 1500* 16,000* 1500* 15,000* 16,000* 12,000*
Polymer Mw 30,100 15,600 7,900 16,200 7,300 6,900 7,400 Polymer Mn
17,100 8,700 4,300 8,200 3,700 3,200 3,200 Polymer Mw/Mn 1.76 1.79
1.84 1.98 1.97 2.16 2.31 Peak crystallization temperature by DSC
(.degree. C.) 55.73 59.05 78.57 69.27 114.76 109.88 116.39 Peak
melting temperature by DSC (.degree. C.) 68 67 91.04 81.97 127.6
120.5 131.11 Total percent crystallinity by DSC 18.94 19.55 36.3
28.18 79.62 72.81 72.84 *Calculated on the basis of melt viscosity
correlations in accordance with the formula: I.sub.2 =
3.6126(10.sup.log(.eta.)-6.6928)/-1.1363) - 9.3185, where .eta. =
melt viscosity at 350.degree. F.
[0173] Polymers E and F and Wax 4 were produced in a solution
polymerization process using a well-mixed recirculating loop
reactor. Each polymer was stabilized with 2000 ppm Irganox.TM. 1076
hindered polyphenol stabilizer (available from Ciba-Geigy
Corporation) and 35 ppm deionized water (as a catalyst kill
agent).
[0174] The ethylene and the hydrogen (as well as any ethylene and
hydrogen which were recycled from the separator, were combined into
one stream before being introduced into the diluent mixture, a
mixture of C.sub.8-C.sub.10 saturated hydrocarbons, for example,
Isopar.TM.-E hydrocarbon (available from Exxon Chemical Company)
and the comonomer 1-octene.
[0175] The metal complex and cocatalysts were combined into a
single stream and were also continuously injected into the reactor.
The catalyst was as prepared in Catalyst Description Two set forth
above; the primary cocatalyst was tri(pentafluorophenyl)borane,
available from Boulder Scientific as a 3 wt percent solution in
ISOPAR-E mixed hydrocarbon; and the secondary cocatalyst was
modified methylalumoxane (MMAO Type 3A), available from Akzo Nobel
Chemical Inc. as a solution in heptane having 2 wt percent
aluminum.
[0176] Sufficient residence time was allowed for the metal complex
and cocatalyst to react prior to introduction into the
polymerization reactor. The reactor pressure was held constant at
about 475 psig (3.3 MPa).
[0177] After polymerization, the reactor exit stream was introduced
into a separator where the molten polymer was separated from the
unreacted comonomer(s), unreacted ethylene, unreacted hydrogen, and
diluent mixture stream, which was in turn recycled for combination
with fresh comonomer, ethylene, hydrogen, and diluent, for
introduction into the reactor. The molten polymer was subsequently
strand chopped or pelletized, and, after being cooled in a water
bath or pelletizer, the solid pellets were collected. Table Two
describes the polymerization conditions and the resultant polymer
properties. TABLE-US-00005 TABLE TWO Polymer E Polymer F Wax 4
Ethylene fresh feed rate (lbs/hr (kg/hr)) 140 (63.5) 140 (63.5) 140
(63.5) Total ethylene feed rate (lbs/hr (kg/hr)) 146.2 (66.32)
146.17 (66.30) 146.5 (66.45) Fresh octane feed rate (lbs/hr
(kg/hr)) 45.4 (20.6) 49.5 (22.4) 12.67 (5.75) Total octene feed
rate (lbs/hr (kg/hr)) Not determined 112 (50.8) 32.9 (14.9) Total
octene concentration (weight percent) Not determined 11.4 3.36
Fresh hydrogen feed rate (standard cm.sup.3/min.) 4025 5350 16100
Solvent and octane feed rate (lbs/hr (kg/hr)) 840 (381) 839.4 (381)
840 (381) Ethylene conversion rate (wt percent) 90.7 90.3 88.26
Reactor temperature (.degree. C.) 109.86 119.8 134.3 Feed
temperature (.degree. C.) 15 15 15.3 Catalyst concentration (ppm)
70 70 70 Catalyst flow rate (lbs/hr (kg/hr)) 0.725 (0.329) 1.265
(0.5738) 4.6 (2.1) Primaxy cocatalyst concentration (ppm) 1200 2031
1998 Primary cocatalyst flow rate (lbs/hr (kg/hr)) 2.96 (1.34)
1.635 (0.7416) 5.86 (2.66) Titanium:boron molar ratio 2.96 3.48
2.897 Secondary cocatalyst concentration (ppm) 198 198 198
Secondary cocatalyst flow rate (lbs/hr (kg/hr)) 0.718 (0.326) 1.258
(0.571) 3.7 (1.7) Titanium:aluminum molar ratio 5 4.986 4.037
Product density (g/cm.sup.3) 0.8926 0.8925 0.9369 Product melt
viscosity at 350.degree. F. (centipoise) 12,500 4,000 400 Polymer
melt index (I.sub.2 at 190.degree. C.)* 686* 1,900* 14,000* Polymer
M.sub.n 12,300* 8,900* 4,700* *Calculated on the basis of melt
viscosity correlations in accordance with the formulas: I.sub.2 =
3.6126(10.sup.log(.eta.)-6.6928)/-1.1363) - 9.3185, M.sub.n =
10.sup.[(log.eta.+10.46)/3.56)] where .eta. = melt viscosity at
350.degree. F.
[0178] Polymer G was prepared as follows. To a 4 liter autoclave
stirred reactor, 865.9 g of Isopar.TM.-E hydrocarbon (available
from Exxon Chemical Company) and 800.4 g 1-octene were charged. The
reactor was heated to 120.degree. C. and hydrogen was added from a
75 cc cylinder. Hydrogen was added to cause a 250 psig (1.7 MPa)
pressure drop in the cylinder. The reactor was then pressurized to
450 psig (3.1 MPa) of ethylene. Catalyst was added at the rate of 1
cc/min. The catalyst was as prepared in the Catalyst Preparation
One set forth above. Prior to introduction into the reactor, the
catalyst was mixed with the cocatalysts at a ratio of 1.5 mL of a
0.005 M solution of Catalyst Preparation One in an inert
hydrocarbon such as Isopar.TM.-E hydrocarbon mixture, 1.5 mL of a
0.015 M solution of tris(pentafluorophenyl)borane in Isopar.TM.-E
hydrocarbon mixture (a 3 wt percent solution of
tris(pentafluorophenyl)borane in Isopar.TM.-E hydrocarbon mixture
is available from Boulder Scientific), 1.5 mL of a 0.05 M solution
of modified methylalumoxane in Isopar.TM.-E hydrocarbon mixture
(MMAO Type 3A) (a solution of MMAO Type 3A in heptane with a 2 wt
percent aluminum content is available from Akzo Nobel Chemical
Inc.), and 19.5 mL of Isopar.TM.-E hydrocarbon mixture. Ethylene
was supplied on demand. The reactor temperature and pressure were
set at 120.degree. C. and 450 psig (3.1 MPa), respectively. The
reaction continued for 23.1 minutes. At this time, the agitation
was stopped and the reactor contents transferred to a glass
collection kettle. The reactor product was dried in a vacuum oven
overnight. The ethylene/octene product thus prepared had a density
of 0.867 g/cm.sup.3, and an I.sub.2 at 190.degree. C. of 842 g/10
min.
EXAMPLES 1-9
HMA's Comprising Polymer, Tackifier, Wax, and Antioxidant
[0179] The indicated polymer, tackifier, wax, and antioxidant were
simultaneously added in the indicated amounts to a Haake Rheocord
40 mixer using a 200 gram mixing bowl maintained at about
130.degree. C. at 95 revolutions per minute. The ingredients were
mixed for about 5 minutes, until they became molten.
[0180] Polymers A-C and Wax 1 were prepared by the procedures set
forth above.
[0181] Polywax 2000 ethylene homopolymer is available from
Petrolite, Inc. (Tulsa, Okla.). Polywax 2000 has a molecular weight
of approximately 2000, an M.sub.w/M.sub.n of approximately 1.0, a
density at 16.degree. C. of about 0.97 g/cm.sup.3, and a melting
point of approximately 126.degree. C.
[0182] CP Hall 1246 paraffinic wax is available from CP Hall (Stow,
Ohio). CP Hall 1246 paraffinic wax has a melting point of
143.degree. F., a viscosity at 210.degree. F. of 4.2 centipoise,
and a specific gravity at 73.degree. F. of 0.915.
[0183] Escorez E1310LC petroleum hydrocarbon resin is a tackifier
available from Exxon Chemical Company (Houston, Tex.). Escorez
E1310LC has a density of 0.97 g/cm.sup.3 at 64{circle around (5)}F,
a molecular weight as determined by gel permeation chromatography
of 1450, a viscosity at 177{circle around (5)}F of 300 centipoise,
and an M.sub.w/M.sub.n of 2.1.
[0184] Foral 105 pentaerythritol ester of hydrogenated rosin is a
tackifier available from Hercules Incorporated (Wilmington,
Del.).
[0185] Piccotac.TM. 115 aliphatic hydrocarbon resin is a tackifier
available from Hercules Incorporated (Wilmington, Del.).
[0186] Irganox.TM. 1010 hindered phenolic antioxidant is available
from Ciba-Geigy.
[0187] Hot melt adhesives HMA-1 through HMA-9 were tested for
initial viscosity and viscosity after three days, using a
Brookfield viscometer at 350.degree. F. (177.degree. C.).
[0188] Hot melt adhesives HMA-3, 4, and 7 were tested for shear
adhesion failure temperature (SAFT) in accordance with the
following procedure. A one inch by one inch (2.5 cm by 2.5 cm) lap
shear bond to case cartons using the indicated HMA in its molten
state, was prepared. Samples were hung vertically in an air
circulating oven at 30.degree. C. with a 500 gram weight suspended
from the bottom of the strip, except in the case of HMA-7 in which
a 100 gram weight was used. The oven temperature was increased by
5.degree. C. every 30 minutes until the adhesive bond failed. The
shear-fail temperature was the average of three SAFT
measurements.
[0189] Hot melt adhesives HMA-1 through HMA-5 were tested for low
temperature adhesion in accordance with the following procedure. A
one inch by one inch (2.5 cm by 2.5 cm) lap shear bond to case
cartons and to 20 point boards, using the indicated HMA in its
molten state, was prepared. The samples were placed in a
refrigerated oven at -30.degree. C. for about 4 hours. The samples
were taken from the oven one at a time and are tested for paper
tear using a 0.125 inch (3 mm) mandrel.
[0190] The hot melt adhesives (HMA's) formulated in this manner are
set forth in the following Table Three, as well as the measured
initial viscosity, viscosity after three days, SAFT, and low
temperature adhesion test results. TABLE-US-00006 TABLE THREE HMA-1
HMA-2 HMA-3 HMA-4 HMA-5 HMA-6 HMA-7 HMA-8 HMA-9 Polymer A (density
= 0.875 g/cm.sup.3; 100 100 100 0 0 0 0 100 100 I.sub.2 = 246 g/10
min.) Polymer B (density = 0.897 g/cm.sup.3; 0 0 100 100 100 100
100 0 0 melt viscosity at 177.degree. C. = 5200 centipoise) Polymer
C (density = 0.870 g/cm.sup.3; 200 200 0 300 200 0 0 0 0 melt
viscosity at 177.degree. C. = 355 centipoise) Wax 1 (density =
0.968 g/cm.sup.3; 0 0 0 0 0 30 30 0 0 melt viscosity at 177.degree.
C. = 395 centipaise) Polywax .TM. 2000 Wax 33 33 22 0 0 0 0 0 0 CP
Hall 1246 Paraffinic Wax 0 0 0 0 0 0 0 40 60 Escorez .TM. E1310LC
Tackifier 33 66 22 0 100 40 0 0 0 Foral .TM. 105 Tackifier 0 0 0 0
0 0 40 0 0 Piccotac .TM. 115 Tackifler 0 0 0 0 0 0 0 40 60 Irganox
.TM. 1010 Antioxidant 0 0 0 0 0 0.25 0.25 0.25 0.25 Initial
viscosity (cPs) 2600 1570 1310 745 570 2020 2080 5700 2710
Viscosity after 3 days (cPs) 2440 1600 2200 2000 545 1900 1935 6050
3300 SAFT (.degree. F. (.degree. C.)) 184 (84) 190 (87.8) 230 (110)
Low temperature adhesion* PT PT PT PT PT *PT indicates paper tear
occurred.
EXAMPLES 10-15
HMA's Not Incorporating Tackifier
[0191] The following formulations are prepared at a polymer:wax
ratio of 90:10 by weight. Polymer F was prepared as set forth
above. The polymers employed in HMA-10, HMA-11, HMA-12, and HMA-13
were substantially linear ethylene/1-octene copolymers prepared in
accordance with the procedures of U.S. Pat. No. 5,272,236. The wax
used was Polywax.TM. 2000 ethylene homopolymer, available from
Petrolite, Inc.
[0192] The samples were prepared by melting the components on a hot
plate with stirring until a uniform mixture was obtained. The
samples were allowed to cool.
[0193] Three small pieces of the polymer/wax samples were placed
approximately 3/8 inch (1 cm) apart on the fiber side of a given
paper board. The other piece of paperboard, coated side to sample,
was placed on top. The structure was placed in a press, maintained
at 180.degree. C. for 15 seconds with approximately 500 psi (3.4
MPa) pressure, and was then removed and cooled. The HMA/paperboard
structures were tested for paper tear.
[0194] A description of the HMA compositions, as well as the
results of the paper tear test are set forth in Table Four.
TABLE-US-00007 TABLE FOUR HMA-10 HMA-11 HMA-12 HMA-13 HMA-14 HMA-15
Polymer density (g/cm.sup.3) 0.87 0.87 0.872 0.86 0.867 0.866
Polymer melt index (I.sub.2 (g/10 min.)) 1 30 70 70 842 981 Weight
percent polymer 90 90 90 90 90 90 Weight percent wax 10 10 10 10 10
10 Paper-to-clay adhesion - Weyerhaeuser board* No No Yes Yes Yes
Yes Paper-to-clay adhesion - SARAN box No No Yes Yes Yes Yes
(Cascade Industries, Canada)* Paper-to-clay adhesion Mead
paperboard* No No Yes Yes Yes Yes *A "yes" result means that paper
tear was observed upon separating the paperboard/HMA/paperboard
laminate; a "no" result means that no paper tear was observed upon
separation.
EXAMPLES 16-24
Evaluation of HMA's for SAFT
[0195] The formulations set forth in Table Five were prepared, with
Polymers A, B, D, and E, and Waxes 2, 3, and 4 being prepared by
the procedures set forth above. The resultant hot melt adhesives
were applied to 20 point paperboard boxes such as are employed in
the packaging of rolls of food packaging film, for example
SARAN-WRAP.TM. (trademark of The Dow Chemical Company), and to a
cardboard such as is employed in cartons for packaging the 20 point
paperboard boxes in case-size quantities.
[0196] The formulations, as well as representative properties
thereof, are set forth in Table Five. TABLE-US-00008 TABLE FIVE
HMA- HMA- HMA- HMA- HMA- HMA- HMA-16 HMA-17 HMA-18 19 20 21 22 23
24 Polymer A (density = 0.875 g/cm.sup.3; 100.0 0 0 0 0 0 0 0 0
I.sub.2 = 246 g/10 min.) Polymer B (density = 0.897 g/cm.sup.3; 0
100.0 0 0 melt viscosity at 177.degree. C. = 5200 centipoise)
Polymer D (density = 0.883 g/cm.sup.3; 0 0 100.0 0 0 0 0 0 0 melt
viscosity at 177.degree. C. = 5000 centipoise) Polymer E (density =
0.893 g/cm.sup.3; 0 0 0 0 0 0 0 100.0 0 melt viscosity at
177.degree. C. = 12,500 centipoise) Polymer F (density = 0.893
g/cm.sup.3; 0 0 0 100.0 100.0 100.0 100.0 0 100.0 melt viscosity at
177.degree. C. = 4000 centipoise) Polywax .TM. 2000 Wax 115.0 0 0 0
0 0 0 0 0 CP Hall 1245 Paraffinic Wax 0 0 0 20.0 20.0 0 0 0 0 Wax 2
(density = 0.948 g/cm.sup.3; 0 40.0 0 0 0 0 0 0 melt viscosity at
177.degree. C. = 350 centipoise) Wax 3 (density = 0.960 g/cm.sup.3;
0 0 60.0 0 0 0 0 0 0 melt viscosity at 177.degree. C. = 512
centipoise) Wax 4 (density = 0.937 g/cm.sup.3; 0 0 0 40.0 40.0
100.0 80.0 80.0 80.0 melt viscosity at 177.degree. C. = 400
centipoise) Escorex .TM. E1310 Tackifier 115.0 0 0 0 0 0 0 0 0
Foral .TM. 105 Tackifier 0 40.0 40.0 40.0 40.0 80.0 0 0 0 Piccotac
.TM. 115 0 0 0 0 0 0 50.0 50.0 50.0 Kaydol .TM. Mineral Oil 0 0 0 0
10.0 0 0 0 20.0 Irganox .TM. 1010 0.7 0.4 0.4 0.4 04 0.6 0.5 0.5
0.5 antioxidant 100 g SAFT 120 125 120 95 105 110 110 110 110 20 pt
paperboard (.degree. C.) 100 g SAFT 120 130 120 105 105 110 110 110
110 cardboard (.degree. C.) Close time (seconds) <5 <5 <5
<5 <10 <5 <5 <5 <5 Open time (seconds) 25 20 25
30 25 35 25 20 30 Viscosity of Hot Melt Adhesive 1030 1940 1422
1037 758 865 1275 2740 942 177.degree. C. (centipoise) Viscosity of
Hot Melt Adhesive 995 1895 1467 920 N/D 800 N/D 2850 930 after 3
days (centipoise) N/D = not determined
Hot Melt Adhesive Formulations for Bonding Polyolefins
[0197] The hot melt adhesive formulation HMA-22, described in Table
Five, was used to demonstrate the ability of the hot melt adhesives
of the invention in the bonding of polyolefin substrates. Several 6
inch (15.2 cm) by 1 inch (2.5 cm) by 0.115 inch (0.292 cm) test
coupons were cut from compression molded plaques of substantially
linear ethylene/1-octene interpolymers available from The Dow
Chemical Company as Affinity SM 1300 (having a density of 0.902
g/cm.sup.3 and a melt index (I.sub.2) of 30 g/10 minutes) and
Affinity SM-8400 (having a density of 0.870 g/cm.sup.3 and a melt
index (I.sub.2) of 30 g/10 minutes).
[0198] In the first experiment, the surface of the coupons of
Affinity SM 1300 was heated to 80.degree. C., and the surface of
the coupons of the Affinity SM 8400 was heated to 60.degree. C. by
heating in convection ovens for 20 minutes, or until the specimens
were brought into thermal equilibrium with the oven environment.
Likewise, HMA-22 was melted and stabilized to 392.degree. F.
(200.degree. C.) in a hot glue gun. The HMA-22 was quickly
dispensed onto the surface of the preheated coupons. One of each
type of coupon was pressed together by applying light finger
pressure, and were immediately further pressed by application of 5
pounds (2.2 kg) force using a 5 pound (2.2 kg) roller. The
composites were allowed to cool to room temperature.
[0199] In the second experiment, the first experiment was repeated,
except that the coupons were not preheated, and the like, the hot
melt adhesive HMA-22 was dispensed at 392.degree. F. (200.degree.
C.) onto coupons which were maintained at room temperature.
[0200] The bonded coupons were tested by peeling by hand. The
specimens of the first experiment exhibited very good adhesion. In
all cases, the samples failed by the Affinity SM 8400 layer failing
in the tensile mode. The specimens of the second experiment showed
a mixed mode of adhesion, as both adhesive and cohesive failures
were present at the same time on most test coupons. The results
were verified by performing T-peel testing on remaining test
coupons. The bonded coupons of the first experiment exhibited an
average T-peel strength of 21.4.+-.2.2 pounds/linear inch (24.7
.+-.2.5 kg/cm). The bonded coupons of the second experiment
exhibited an average T-peel strength of 14.7.+-.0.9 pounds/linear
inch (17.0.+-.1 kg/cm).
Hot Melt Adhesive Formulations of Ethylene/.alpha.-olefins with
Ethylene Acrylic Acid and Ethylene Vinyl Acetate
[0201] The polymers, tackifier, wax, and antioxidant were
simultaneously added in the indicated amounts to a Haake Rheocord
40 mixer using a 200 g mixing bowl maintained at about 130.degree.
C. at 95 revolutions per minute. The ingredients were mixed for
about 5 minutes, until they became molten.
[0202] Ethylene acrylic acid (EAA) 5990 is commercially available
from The Dow Chemical Company. Ethylene vinyl acetate (EVA-Elvax
210; 28 percent VA, 200 g, 10 min. melt index) is commercially
available from E.I. duPont de Nemours Company. Viscosity, viscosity
after 3 days, open and close times, 500 gram SAFT, 100 gram SAFT,
100 gram PAFT and low temperature mandrel tests were performed as
set forth above.
[0203] Sample HMA 25 is formulated from 100.0 phr of a homogeneous
ethylene/1-octene interpolymer having a density of 0.890 g/cc and a
melt viscosity at 350.degree. F. (177.degree. C.) of 5000
centipoise, 30.0 phr of a homogeneous ethylene homopolymer having a
density of 0.960 g/cc and a melt viscosity at 350.degree. F.
(177.degree. C.) of 300 centipoise, 40.0 phr of Foral.TM. 105
tackifier, 0.3 phr of Irganox.TM. 1010 antioxidant, and 18.9 phr
Primacorm.TM. 5990 ethylene acrylic acid copolymer. The formulation
has a melt viscosity at 350.degree. F. (177.degree. C.) of 2775
centipoise, a close time of 5 seconds, an open time of 10 seconds,
a 100 gram SAFT of 100.degree. C., a 500 gram SAFT of 115.degree.
C., a PAFT of 115.degree. C., and a low temperature mandrel test
which indicates 1/4 partial paper fail of Container Corporation of
America.
[0204] Sample HMA 26 is formulated from 100.0 phr of a homogeneous
ethylene/1-octene interpolymer having a density of 0.890 g/cc and a
melt viscosity at 350.degree. F. (177.degree. C.) of 5000
centipoise, 30.0 phr of a homogeneous ethylene homopolymer having a
density of 0.960 g/cc and a melt viscosity at 350.degree. F.
(177.degree. C.) of 300 centipoise, 40.0 phr of Foral.TM. 105
tackifier, 0.3 phr of Irganox.TM. 1010 antioxidant, and 18.9 phr
Elvax.TM. 210 EVA. The formulation has a melt viscosity at
350.degree. F. (177.degree. C.) of 3075 centipoise, a close time of
5 seconds, an open time of 10 seconds, a 100 gram SAFT of
100.degree. C., a 500 gram SAFT of 120.degree. C., a PAFT of
125.degree. C., and a low temperature mandrel test which indicates
1/4 partial paper fail of Container Corporation of America.
II. Hot Melt Pressure Sensitive Adhesive Examples
Preparation of Adhesive Formulations
[0205] The indicated polymer, tackifier, plasticizer, and
antioxidant were simultaneously added in the indicated amounts to a
Haake Rheocord 40 mixer using a 200 gram mixing bowl maintained at
about 130.degree. C. at 95 revolutions per minute. The ingredients
were mixed for about 5 minutes, until they became molten.
[0206] Escorez.TM. 5300 petroleum hydrocarbon resin is a tackifier
available from Exxon Chemical Company (Houston, Tex.). Escorez.TM.
5300 has a density of 1.09 g/cm.sup.3, a weight average molecular
weight of 354, a number average molecular weight of 354, and an
M.sub.w/M.sub.n of 1.43.
[0207] Irganox.TM. B900 hindered phenolic antioxidant is available
from Ciba-Geigy.
[0208] Irganox.TM. 1010 hindered phenolic antioxidant is available
from Ciba-Geigy.
[0209] Polyisobutylene is available from Amoco.
[0210] Examples PSA-27 through PSA-32 were tested for initial
viscosity and viscosity after three days, using a Brookfield
viscometer at 350.degree. F., probe tack, modulus (G'), and peak
tan delta. The formulations and the measured properties are set
forth in Table Six. Note that in the case of modulus and peak tan
delta, the reported values were extracted from a computer-generated
plot of the results.
[0211] As illustrated in Table Six, the adhesives of Examples 27,
29, 30, 31 and 32 meet the Dahlquist criteria, indicating their
suitability as a traditional PSA, with Examples 27, 29, 30, and 31
further meeting the criteria that the glass transition temperature
range from -20 to 20.degree. C. Examples 27 and 28 illustrate the
trend that as number average molecular weight decreases, storage
modulus likewise decreases. Example 29 illustrates the use of added
tackifier to increase the glass transition temperature of the
formulation.
[0212] Dual molecular weight blends appear to offer a unique
balance of properties which are not in accordance with the law of
mixtures. In particular, while the blend of Example 31 has a
storage modulus (G') at 25.degree. C. which is intermediate that of
Examples 27 and 28, the probe tack of Example 31 exceeded that of
Example 28, indicating that the blends of the invention offer a
synergistic behavior.
[0213] As further illustrated in Table Six, Example 27 may be
employed as a cold temperature label or a PSA tape, Example 24 may
be employed as a PSA tape, Example 30 may be employed as a low peel
label or a freezer label; Example 31 may be employed in high peel
labels or disposables applications; Example 32 may be employed in
PSA tape. TABLE-US-00009 TABLE SIX PSA-27 PSA-28 PSA-29 PSA-30
PSA-31 PSA-32 Polymer G (density = 0.867 g/cm.sup.3; 0 100/45.2 0 0
50/22.6 0 I.sub.2 = 842 g/10 min.) Substantially linear
ethylene/1-octene interpolymer 100/45.2 0 100/36.9 0 50/22.6 0
(density = 0.864 g/cm.sup.2; I.sub.2 = 13 g/10 min.) Affinity .TM.
EG 8200 (0.870 g/cm.sup.3; I.sub.2= 5 g/10 min.) 0 0 0 100/41.5 0 0
Affinity .TM. EG 8180 (0.863 g/cm.sup.3; 50/22.7 I.sub.2 = 0.5 g/10
min.) Substantially linear ethylene/1-octene interpolymer 50/22.7
(0.885 g/cm.sup.3; I.sub.2 = g/10 min.) Escorez .TM. 5300 (Exxon)
100/45.2 100/45.2 150/55.4 0 100/45.2 0 Indopol .TM. (Amoco) 0 0 0
125/51.9 0 100/45.5 Drakeol .TM. 34 (Premcor) 20/9.0 20/9.0 20/7.4
0 20/9.0 20/9.1 Duoprime .TM. 200 (Lyondell) 0 0 0 15/6.2 0 0
Irganox .TM. B900 (Ciba Geigy) 1/0.5 1/0.5 1/0.4 0 1/0.5 0 Irganox
.TM. 1010 Antioxidant 0 0 0 1/0.4 0 0 Viscosity at 350.degree.
(cPs) Probe tack (g) 50 329 153 129 552 0 G' at 0.degree. C.
(dynes/cm.sup.2(Mpa)) 1.26 .times. 10.sup.7 1.26 .times. 10.sup.6
3.98 .times. 10.sup.7 1.78 .times. 10.sup.6 5.62 .times. 10.sup.6
5.01 .times. 10.sup.7 (1.26 MPa) (0.126 MPa) (3.98 MPa) (0.178 MPa)
(0.562 MPa) (5.01 MPa) G' at 25.degree. C. (dynes/cm.sup.2) 2.00
.times. 10.sup.6 3.98 .times. 10.sup.4 1.41 .times. 10.sup.6 5.62
.times. 10.sup.5 7.08 .times. 10.sup.5 5.89 .times. 10.sup.6 (0.200
MPa) (0.00398 MPa) (0.141 MPa) (0.0562 MPa) (0.0708 MPa) (0.589
MPa) G' at 50.degree. C. (dynes/cm.sup.2) 3.16 .times. 10.sup.5 NA
1.78 .times. 10.sup.5 1.58 .times. 10.sup.5 3.16 .times. 10.sup.4
2.24 .times. 10.sup.6 ((0.0316 MPa) (0.0178 MPa) (0.0158 MPa)
(0.00316 MPa) (0.224 MPa) G' at 75.degree. C. (dynes/cm.sup.2) 2.00
.times. 10.sup.4 NA 1.58 .times. 10.sup.4 7.08 .times. 10.sup.3
3.98 .times. 10.sup.3 2.51 .times. 10.sup.5 (2.00 kPa) (1.58 kPa)
(0.708 kPa) (0.398 kPa) (25.1 kPa) Temp. at which G' = 10.sup.4
dynes/cm.sup.2 (10 kPa) (.degree. C.) 90 32 79 74 57 90 Temp. at
which G' = 10.sup.5 dynes/cm.sup.2 (100 kPa (.degree. C.) 59 21 55
55 43 147 Peak tan delta (.degree. C.) -12 -21 0 -55 17 0
[0214] Likewise, pressure sensitive adhesives may be prepared using
a substantially linear ethylene polymer in combination with
tackifier and a high density polyethylene having a lower molecular
weight as indicated by a melt index (I.sub.2) of 25 g/10 min. As
set forth in the following Table Seven, such pressure sensitive
adhesives exhibit probe tack values comparable to the adhesive used
on Scotch.TM. magic tape (368 g). TABLE-US-00010 TABLE SEVEN PSA-33
PSA-34 Substantially linear ethylene/1-octene 17.4 percent 17.4
percent interpolymer (density = 0.855 g/cm.sup.3; I.sub.2 = 1 g/10
min) HDPE 2455 (density = 0.955 g/cm.sup.3, 7.5 percent I.sub.2 =
25 g/10 min) Affinity .TM. SM 1300 (density = 0.902 7.5 percent
g/cm.sup.3; I.sub.2 = 30 g/10 min) Escorez .TM. 1310LC (Exxon) 54.9
percent 54/9 percent Kaydol .TM. (Witco) 20.7 20.7 Irganox .TM.
1010 Antioxidant 0.25 0.25 Viscosity at 350.degree. F. (177.degree.
C.) (cPs) 42,000 24,650 Probe tack (g) 537 264
III. Application Specific Adhesive Examples
[0215] The following examples were made using a sigma blade mixer
or a vertical upright mixer with standard hot melt blending
techniques and tested in accordance with the test methods described
above. Unless indicated otherwise, the homogeneous
ethylene/.alpha.-olefin interpolymers utilized in the examples are
depicted in the following Table Eight. The presentation of the
examples in this manner is a matter of convenience and is in no way
intended to be limiting. Adhesive examples targeted for specific
end-use applications also have utility for other applications.
TABLE-US-00011 TABLE EIGHT Melt Index (I.sub.2 in Density Supplier
Designation g/10 min) (g/cm.sup.3) Comonomer Exxon Exxpol SLP-0380
20 0.865 Propylene Exxon Exxpol SLP-0394 5 0.865 Propylene Exxon
Exxpol SLP-0397 120 0.885 Propylene Exxon Exxpol SLP-0527 125 .901
Butene Exxon Exxpol SLP-0592 10 0.865 Butene Exact 5008 Exxon
Exxpol SLP-0599 20 0.865 Butene Exxon Exxpol SLP-0173 3.5 .910
Hexene Exxon Exxpol SLP-0728 3.5 .900 Hexene Exact 3031 Dow SM-1300
30 .902 Octene Dow SM-8400 30 .870 Octene Dow EG-8150 0.5 .870
Octene Dow EG-8200 5 .870 Octene Dow EG-8100 1 .870 Octene Dow
SM1250 30 .885 Octene Dow DPF 1150-01 0.9 .901 Octene Dow *EIP 4 28
.868 Octene Dow EIP 5 1 .858 Octene Dow EIP 6 30 .855 Octene Dow
EIP 7 200 .870 Octene Dow EIP 8 100 .900 Octene Dow EIP 9 100 .855
Octene Dow EIP 10 ** 5000 cps .870 Octene Dow EIP 11 ** 5000 cps
.890 Octene Dow LDPE 959S 60 .920 Octene EIP-Experimental
Substantially Linear Ethylene/1-Octene Interpolymer; *In-reactor 5
mixture; ** Brookfield Viscosity (MI not measurable)
[0216] TABLE-US-00012 TABLE EIGHT A Other Ingredients Tradename
Description Supplier Tackifying Resins Escorez 2520 C.sub.5/C.sub.9
hydrocarbon blend Exxon Escorez 5400 (ECR-177) hydrogenated
dicyclopentadiene Exxon Escorez 2520 C.sub.5/C.sub.9 hydrocarbon
blend Exxon Escorez 2520 C.sub.5 hydrocarbon Exxon Eastotac H-100
hydrogenated C.sub.9 Eastman Eastotac H-130 hydrogenated C.sub.9
Eastman Sylvatac 1103 rosin ester Arizona Plasticizers *500
napthenic oil Penzoil *1200 napthenic oil Penzoil Kaydol white
mineral oil Witco Parapol 1300 1300 M,,polybutene Exxon Benzoflex
352 1,4 cyclohexane dimethanol Velsicol dibenzoate Waxes Victory
.RTM. Amber Wax * 160.degree. F. Microwax Petrolite Castorwax
hydrogenated castor oil Caschem Okerin .RTM. 236 TP parafin
155.degree. F. Astor Wax Paraflint H4(* HMP Wax) 225.degree. F.
Fischer Tropsch Moore & Munger Besquare .RTM. 195 195.degree.
F. Microwax Petrolite Bareco PX-100 225.degree. F. Fischer Tropsch
Bareco Modifying Polymers Kraton .RTM. G-1657 13 percent styrene,
35 percent Shell diblock styrene-ethylene- butylene-styrene block
copolymer Elvax 260 28 percent vinyl acetate, 5 melt Dupont index
Elvax 150 33 percent vinyl acetate, 44 melt Dupont index Elvax 410
18 percent vinyl acetate, Dupont 500 melt index *EnBA 35 percent
BA, 320 melt index HL-2660 Polyamide H.B. Fuller Co. HL-6088
Polyamide H.B. Fuller Co. Petrothene NA 601 .903 g/cm.sup.3, 2000
melt index low Petrolite density polyethylene Epolene C-15 .906
g/cm.sup.3, 4200 melt index Eastman polyethylene Irganox 1010
hindered phenol antioxidant Ciba- Giegy * Description rather than
tradename indicated in the examples.
Nonwoven Construction Adhesives
[0217] Adhesives of the invention for use as nonwoven construction
adhesives are set forth below in Tables Nine and Nine A.
[0218] Examples 35-57 of Table Nine represents nonwoven
construction adhesives useful for the assembly of various
disposable articles such as disposable diapers, sanitary napkins,
surgical gowns, and the line wherein a body fluid impermeable
backsheet is typically bonded to a nonwoven substrate. The
disposable article of the present invention comprises at least two
layers wherein at least one of said layers is a body fluid
impermeable barrier and at least one of said second layers is a
body fluid permeable cover; wherein at least one layer is attached
to at least one other layer by the adhesive composition of the
present invention. The disposable article may also optionally
contain at least one layer or material selected form the group
consisting of absorbents, tissues, elastomeric materials,
superabsorbent polymers, and combinations thereof. The body fluid
cover is typically a polyolefin film, such as polyethylene,
polypropylene, ethylene-vinyl acetate, and especially a homogeneous
ethylene/.alpha.-olefin interpolymer film, provided as a roll good.
Alternatively, the barrier layer can be made in-line by coating a
thermoplastic composition to a carrier material such as a nonwoven.
In-line film forming is of particular interest for materials which
are unsuitable, due to tack, undesirable rheological properties, or
any other constraint which renders the material undesirable for
making prefinished roll goods. Preferably, in-line barriers are
made using a noncontact slot coat application method described in
detail in H. B. Fuller's copending PCT application, Application No.
EP 96/00377 filed Jan. 30, 1996.
[0219] The majority of the adhesives examples are pressure
sensitive in nature. However, some of the examples, particularly
those comprising Benzoflex 352 or alternatively relatively high
concentrations of the homogeneous ethylene/.alpha.-olefin
interpolymer, and the like, greater than about 40 weight percent of
the homogeneous ethylene/.alpha.-olefin interpolymer, are
relatively tack-free upon cooling. Examples NW-44 and NW-45 are
substantially tack-free upon cooling and are intended for nonwoven
to nonwoven bonding. The bonds were made and evaluated in
accordance with the previously mentioned "Fineline and Spray" test
method. The application conditions and resulting peel results are
recorded in Table Ten.
[0220] Surprisingly, as illustrated in Table Ten, these adhesive
compositions have excellent spray properties and spray bond
strengths, even though the viscosity at application temperature is
significantly higher than a typical block copolymer based adhesive
composition, such as HL-1280 (H. B. Fuller), an industry standard
nonwoven construction adhesive for bonding polyolefin films.
Although nonwoven construction adhesives are exemplified, the
adhesives of the present invention are also surmised to be suitable
for elastic attachment, frontal tape, as well as multipurpose
nonwoven applications.
[0221] Polyolefin films comprising homogeneous
ethylene/.alpha.-olefin interpolymers are becoming increasingly
popular due to their reduced stiffness and improved tactile quality
in comparison with conventional polyethylene films. The adhesives
of the present invention are expected to exhibit even higher bond
strength on films comprising homogeneous ethylene/.alpha.-olefin
interpolymers. TABLE-US-00013 TABLE NINE Nonwoven Construction
Adhesives 5402- HL- 4156-77-1 4156-80- 4156-78-1 5179-10- 5402-42-
4-1 1624 HL-1617 HL-1625 NW- NW- 5338-57- Ingredient NW-35 1 NW-36
NW-37 1 NW-38 1 NW-39 NW-40 NW-41 NW-42* NW-43* 44 45 2 NW-46
SLP-0592 25.0 25.0 SLP-0599 25.0 EIP 6 17 DPF-1150.01 3 XUR 5990100
22 20 EIP 4 EIP 7 40 EG 8200 16 12 12 0.87 g/cm.sup.3/2200 50 MI**
0.86 g/cm.sup.3/200 70 MI** Escorez 2520 25.0 25.0 (Exxon) Escorez
5320 55 55 (Exxon) Escorez 5400 49.0 49.0 49.0 55 50 55 56.8 50 30
(Exxon) Escorez 2596 56.8 500 Napthenic 23 10 27 28 28 Oil Kaydol
25 25 Benzoflex 352 25.0 (Velsicol) Irganox 1010 1.0 1.0 1.0 .2 .2
.2 Viscosity @ 150,000 78,000 110,000 8,175 8,400 250.degree. F.
(cps) @ 275.degree. F. (cps) 81,000 42,000 65,000 13,900 4,375
4,640 @ 300.degree. F. (cps) 48,000 24,500 40,000 7650 8,000 2,600
2,740 @ 325.degree. F. (cps) 29,500 15,000 25,000 5000 8425 3733
4,890 1,996 1,710 4395 @ 350.degree. F. (cps) 19,000 9,375 17,500
3,095 1,135 **Substantially linear ethylene/1-octane interpolymers
available from The Dow Chemical Company; All amounts are in pph;
Examples indicated by * further contain 2 weight percent Paraflint
C-80
[0222] TABLE-US-00014 TABLE NINE-A 5179-22-2 5338-53-1 5402-18-2
5338-53-2 Comparative Reference # NW-47 NW-48 NW-49 NW-50 NW-51
Example B EIP 5 10 6 14 DPF 1150.01 6 EIP 4 25 Rextac 2385 25
(Rexene) EIP 10 30 EIP 11 30 6 ECR 177 65 60 62 55 Escorez 5320 40
18 55 Kaydol 25 23 20 20* Visc @ 300 F. 4300 1025 Visc @ 325 F.
3250 5500 20500 8813 All amounts are as weight percent. Comparative
Example B indicated by * utilizes 500 Napthenic Oil in place of
Kaydol oil
[0223] TABLE-US-00015 TABLE TEN Nonwoven Construction Bonding
Results Adhesive Fineline Peel Temperature (.degree. F. Air
Pressure Spiral Spray Peel (g/lineal in. Example (.degree. C.))
(psi (MPa)) (g/lineal in. (g/cm)) (g/cm)) Comments NW-35 350 (177)
30 (0.21) 210 (40) 340 (160) Destructive Bonds NW-36 300 (149) 26
(0.18) 190 (20) 211 (40) Destructive Bonds NW-38* 275 (135) 126
(12) 55 (5) Cohesive Failure, Low Application Temperature NW-39 325
(163) 28 (0.19) 162 (19) 203 (27) Destructive Bonds NW-40 300-325
(149-163) 116 (19) 64 (7) NW-41 275-300 (135-149) 15 (0.10) 140
(55) 125 NW-42 275 (135) 6 (0.041) 125 (49) 115 NW-43 300 (149) 7
(0.048) 125 (49) 115 NW-44 300 (149) 7 (0.048) 79 (9) 123 (15)
NW-45 not tested NW-46 325 (163) 15 (0.10) 142 (18) 125 (18) NW-47
300 (149) 12 (0.083) 31 (7) 82 (21) NW-48 300-325 (149-163) 107
(14) 59 (10) Very Soft NW-49 300 (149) 151 (36) 103 (17) NW-50 325
(163) 15 (0.10) 184 (32) 235 (76) Destructive Bonds NW-51 325 (163)
129 (21) 160 (51) Comparative B 300 (163) 35 (20) 6 (3) Comparative
275 (135) 15 (0.10) 95** (37) 175** (69) (** running average)
A-HL-1280 *NW-37 not tested
Thermal Stability Testing
[0224] The pressure sensitive adhesives of Examples NW-41 through
NW-45 were tested for thermal stability. The results are set forth
in the following Table Eleven. As is exemplified by these thermal
stability results, the adhesives of the present invention exhibit
tremendously improved viscosity stability relative to block
copolymer based adhesive compositions. TABLE-US-00016 TABLE ELEVEN
Thermal Stability Testing (Brookfield viscosity at 300.degree. F.
(149.degree. C.) (cps)) Delta Delta Viscosity 0 24 hrs 48 hrs 72
hrs 96 hrs 200 hrs 96 200 HL1280 2645 2425 2310 2065 1990 -- -25 --
(HL-1624) 9950 9900 9825 10200 10350 10450 4.0 5.0 NW-41 (HL-1617)
2735 2540 2515 2650 2560 2750 -6.4 0.5 NW-42 (5576-3- 9575 9550
9525 9475 9800 9400 2.3 -1.8 3) NW-43 (HL-1625) 2300 2320 2130 2450
2440 2385 6.1 3.7 NW-44
Positioning Adhesive
[0225] Positioning adhesives are typically pressure sensitive in
nature and is sandwiched between the garment facing surface of a
feminine napkin and release paper. Upon use the release paper is
removed and the napkin is secured to an undergarment by means of
the positioning adhesive. The current state of the art with respect
to positioning adhesives can be found in U.S. Pat. Nos. 4,136,699,
5,149,741 and 4,704,110. Pressure sensitive adhesives for use as
positioning adhesives, as well as representative performance
attributes thereof, are set forth in the following Table Twelve.
TABLE-US-00017 TABLE TWELVE Positioning Adhesives 52 53 54 SLP-0592
25.0 20.0 20.0 SLP-0597 49.0 5.0 5.0 Eastotac H-130 49.0 49.0 --
ECR-177 -- -- 49.0 Kaydol Oil 25.0 25.0 25.0 Irganox 1010 1.0 1.0
1.0 Initial T-Peel to 365 g (5) 298 g (16) 172 g (23) Cotton (1
mil) Initial T-Peel to 478 g (19) 406 g (13) 216 g (26) Cotton (2
mil)
(95 Percent Confidence Intervals) Additional PSA Applications
[0226] The adhesives of the invention may be utilized as adhesives
for use in industries other than nonwoven and personal care items.
For instance, Examples 55-58 represent packaging PSA formulations
for bonding rigid polyolefin containers (lunch meat containers) and
for bottle labeling applications. Examples 55-56 demonstrate the
utility of employing block copolymers, particularly in small
concentrations, in combination with the essential homogeneous
ethylene/.alpha.-olefin interpolymer.
[0227] Example 59 represents an example of a "foam in place" gasket
wherein the compositions serves a multipurpose of bonding, sealing,
and gasketing.
[0228] Examples 60 and 61 represent rodent trap adhesives which are
a substantial cost savings relative to existing technology.
Typically, block copolymer-based adhesives for this application
comprise from about 5 to about 20 percent by weight of the block
copolymer. The adhesive composition covers the bottom surface of a
container such as box and is subsequently baited to form a trap.
Often an additive is incorporated directly into the adhesive which
attracts rodents and eliminates the need for consumer-provided
bait. The adhesive exhibits high tack and cohesive strength to
restrain the rodent.
[0229] The various additional PSA examples, and representative
performance attributes thereof, are set forth in the following
Table Thirteen: TABLE-US-00018 TABLE THIRTEEN Additional Pressure
Sensitive Adhesive Examples Reference # Ingredient (4230-44-1)
(4230-40-1) (4230-39-1) (4230-39-2) (4156-80-2) (4231-1-1)
(4231-1-2) Trade name Example 55 Example 56 Example 57 Example 58
Example 59 Example 60 Example 61 SLP-0592 9.0 11.7 15.0 14.6 10.0
SLP-0599 30.0 10.0 Kraton .TM. 6.0 2.9 G-1657 (Shell) Eastotac .TM.
H-100 42.5 41.5 42.5 41.5 (Eastman) ECR-177 (Exxon) 44.0 Escorez
.TM. 1310 44.0 (Exxon) 500 Oil 37.5 39.0 40.0 39.0 (Naphthenic)
1200 Oil 45.0 45.0 (Naphthenic) Kaydol Oil 40.0 Microwax 160 5.0
4.9 Castor Wax 2.5 4.9 Parafin 155 30.0 Irganox 1010 1.0 1.0
Viscosity @ 250.degree. F. 6275 cps (121.degree. C.) @ 275.degree.
F. (135.degree. C.) 3810 @ 300.degree. F. (149.degree. C.) 2415 @
325.degree. F. (163.degree. C.) 1600 @ 350.degree. F. (177.degree.
C.) 1112 All percentages are by weight percent
Adhesive Formulations Comprising Homogeneous
Ethylene/.alpha.-Olefin Interpolymers and EVA:
[0230] The adhesives of the invention may further include, in
additional to the homogeneous ethylene/.alpha.-olefin interpolymer,
one or more ethylene vinyl acetate copolymers. In particular, given
the compatibility of homogeneous ethylene/.alpha.-olefin
interpolymers with EVA, adhesives comprising such a combination of
polymers will find utility in, for instance, bookbinding
applications as well as others where it is necessary for the hot
melt adhesive to lose surface tack quickly after application to
insure that the adhesive does not build up on the trimmer knives.
Also, this compatibility facilitates the need to adjust the set
time to accommodate various application equipment. Representative
of such hot melt adhesive formulation comprising EVA which has from
18 to 33 weight percent vinyl acetate content, as well as
representative performance attributes thereof, are set forth in the
following Table Fourteen: TABLE-US-00019 TABLE FOURTEEN Adhesives
Comprising Homogeneous Ethylene/.alpha.-olefin Interpolymers and
EVA Reference # Trade Name 4036-41-1 4036-41-2 4036-41-3 4036-41-4
4036-41-5 4036-41-6 4036-41-7 Ingredient Example 62 Example 63
Example 64 Example 65 Example 66 Example 67 Example 68 SLP-0380
40.0 40.0 40.0 40.0 30.0 30.0 30.0 Eastotac 39.5 39.5 39.5 39.52
59.5 59.5 59.5 H-100 Parafin 155 20.0 Irganox 1010 .5 .5 .5 .5 .5
.5 .5 Elvax 260 (28 20.0 10.0 percent vinyl acetate) Exvax 150 (33
20.0 10.0 percent vinyl acetate) Elvax 410 (18 20.0 10.0 percent
vinyl acetate) All amounts are in weight percent.
Bookbinding Adhesives
[0231] Certain of the claimed adhesives will find particular
utility in the graphic arts industry as bookbinding adhesives. The
target property ranges set forth in the following Table Fifteen can
be achieved with the adhesives of the invention. TABLE-US-00020
TABLE FIFTEEN Target Bookbinding Properites Viscosity at Ambient
350.degree. F. 100 g Peel Cold Crack Range* Tensile Useful
.ltoreq.10,000 cps .gtoreq.120.degree. F. (49.degree. C.)
.ltoreq.40.degree. F. (4.4.degree. C.) .gtoreq.80.degree. F.
(27.degree. C.) .gtoreq.350 psi (2.4 MPa) Good <8,000 cps
>130.degree. F. (54.degree. C.) <30.degree. F. (-1.degree.
C.) >100.degree. F. (38.degree. C.) >500 psi (3.4 MPa)
Excellent <6,000 cps >140.degree. F. (60.degree. C.)
<20.degree. F. (-7.degree. C.) >120.degree. F. (49.degree.
C.) >600 psi (4.1 MPa) *The ambient ranges is defined as the
difference between the 100 g peel and the cold crack.
[0232] Representative bookbinding adhesives and representative
performance attributes thereof are set forth in the following
Tables Sixteen A and B.
[0233] As exemplified in Tables Sixteen A and B, for bookbinding
applications it is preferred to employ a homogeneous
ethylene/.alpha.-olefin interpolymer having a density of 0.870
g/cm.sup.2 or less and a relatively low melt index, for example
ranging from 10 to 20 g/10 min., at concentrations of 30 weight
percent or less. To reduce the viscosity of the adhesive
composition it is preferable to blend a second homogeneous
ethylene/.alpha.-olefin interpolymer having a melt index ranging
from 100 to 2000 g/10 min. in combination with the low melt index
homogeneous ethylene/.alpha.-olefin interpolymer. It is a
surprising result that adhesives can be prepared with this low
density homogeneous ethylene/.alpha.-olefin interpolymer without
sacrificing heat resistance. Microwaxes are preferred waxes for
bookbinding applications, particularly when combined with polar
tackifiers such as rosin esters, rosin acids, hydrogenated rosin
esters, terpene resins, styrenated terpenes, terpene phenolics, and
mixtures thereof. TABLE-US-00021 TABLE SIXTEEN A Bookbinding
Adhesives 4036-43-1 4036-43-2 Example Example 4036-49-1 4036-49-2
4036-49-3 Ingredient 69 70 Example 71 Example 72 Example 73 Example
74 Example 75 Example 76 Example 77 SLP-0380 40.0 35.0 40.0 20.0
15.0 15.0 SLP-0397 20.0 40.0 20.0 20.0 SLP-0527 25.0 20.0 SLP-0592
10.0 15.0 Eastotac 39.5 39.5 34.5 34.5 34.5 44.5 44.5 44.5 H-100
Eastotac 44.5 H-130 HMP Wax 20 25.0 12.5 12.5 12.5 20.0 20.0 20.0
20.0 (Fischer Tropsch, 225 mp) Irganox 1010 .5 .5 .5 .5 .5 .5 .5 .5
.5 Paraffin 155 12.5 12.5 12.5 PAFT (.degree. F. 140 (60) 138 (59)
112 (44) 112 (44) 105 (41) 128 (53) 139 (59) 141 (61) 147 (64)
(.degree. C.)) SAFT (.degree. F.) 193 (89) 194 (90) 173 (78) 173
(78) 174 (79) 192 (89) 191 (88) 199 (93) 197 (92) Cold Crack 10
(-12) 20 (-7) 5 (-15) 15 (-9) 25 (-3.9) 20 (-7) 30 (-1) 45 (7.2) 30
(-1) (.degree. F.) Ultimate 510 (3.4 MPa) 526 697 (4.8 MPa) 606
Tensile (psi) (4.1 MPa) Viscosity @ 32,000 20,100 26,200 14,500
6,675 10,350 11,800 8562 12,875 350.degree. F. (177.degree. C.)
(cps) All amounts are by weight percent.
[0234] TABLE-US-00022 TABLE SIXTEEN B Bookbinding Adhesives
Ingredient Example 78 Example 79 Example 80 Example 81 Example 82
Example 83 Example 84 Example 85 0.87 g/cm.sup.3/I.sub.2 = 10 g/ 14
10 min** 0.864 g/cm.sup.3/I.sub.2 = 14 g/ 14 22.5 25 25 25 25 25
20.5 10 min** 0.873 g/cm.sup.3; I.sub.2 = 2200 10 g/10 min** 0.864
g/cm.sup.3; Melt 10 10 10 10 10 15 viscosity at 177.degree. C. =
10000 cps*** Paraflint H4 25 25 11 Escorez 5400 46.5 21 + 21*
Eastatac 42.5 39.5 29.5 24.5 20 H-100-R 195.degree. F. Microwax 25
25 25 25 25 11 Nirez 2019 10 15 19.5 39.5 Irganox 1010 .2 .5 .2 .2
.2 .2 .2 .5 Irganox 1076 .3 .3 .3 .3 .3 .3 Cold Crack (.degree. F.
25 (-3.8) 10 (-12) -5 (-21) 0 (-18) 5 (-15) 5 (-15) 5 (-15) 10
(-12) (.degree. C.)) Ambient Range 115.6 (46) 132 (56) 138 (59) 139
(59) 132.5 (56) 128.5 (54) 127 (53) 128 (53) (.degree. F. (.degree.
C.) 100 g Peel (.degree. F.(.degree. C.)) 140 (60) 142 (61) 133
(56) 139.2 (60) 137.5 (59) 133.8 (57) 132 (56) 138 (59) Viscosity @
350.degree. F. 9250 4750 7215 7325 7825 7625 7440 5900 (177.degree.
C.) (cps) Ultimate Tensile 591 (4.07) 561 (3.87) 369 (2.54) 403
(2.78) 408 (2.81) 429 (2.96) 542 (3.74) 366 (2.52) (psi(Mpa))
*Escorez 5615 **Substantially linear ethylene/1-octene
interpolymers; homogeneous ethylene/1-octene interpolymer (all
available from The Dow Chemical Company) All amounts are reported
in weight percent.
Case and Seal Adhesive
[0235] The hot melt adhesives of the invention will find particular
utility as case and carton seal adhesives. Representative adhesives
for case and carton sealing, and representative performance
attributes thereof, are set forth in the following Table Seventeen.
Table Seventeen illustrates the utility of blending small
concentrations of the homogeneous ethylene/.alpha.-olefin
interpolymer with a second polyethylene, resulting in improved cold
temperature properties and heat resistance. TABLE-US-00023 TABLE
SEVENTEEN Case and Carton Seal Adhesives 4056-43-1 4056-46-1
4056-60-1 4056-65-1 4056-65-2 4056-65-3 4056-65-4 Example 53
Example 54 Example 55 Example 56 Example 57 Example 58 Example 59
HL 7400 Eastotac H-100 50 50 35 35 35 35 35 30 (Eastman) SLP-0599
12 10 SM-8400 10 SLP-0380 10 SLP-0738 10 Epolene C-15 20 32 50 50
50 50 60 (Eastman) Paraflint H-4 18 18 5 5 5 5 5 Petrothene 70
NA601 Viscosity @ 1325 1800 2025 2900 2800 7600 730 2025
350.degree. F. (177.degree. C.) (cPs) Bonding Testing Corrugated:
Room Temp 1 4 1 1 1 1 1 1 40.degree. F. (4.4.degree. C.) 2 4 1 1 1
1 4 4 0.degree. F. (-18.degree. C.) 4 4 1 3 3 1 4 4 PAFT (.degree.
F. (.degree. C.)) 147 (64) 88 (31) 138 (59) 120 (49) 130 (54) 138
(59) 110 (43) 105 (41) SAFT (.degree. F. (.degree. C.)) 192 (89)
197 (92) 190 (88) 190 (88) 190 (88) 190 (88) 190 (88) 197 (92) All
amounts are reported in weight percent. 1 = Full Fiber Tear 2 =
Shallow Fiber Tear 3 = Partial Fiber Tear 4 = No Fiber Tear HL
7400, Commercial Case and Carton Seal (HB Fuller)
Packaging Adhesives
[0236] The hot melt adhesives of the invention will find utility in
a variety of packaging applications. Their success in such
applications is attributable in part to the fact that by employing
the essential homogeneous ethylene/.alpha.-olefin interpolymer, a
good balance of heat resistance (PAFT/SAFT) and cold temperature
properties can be achieved. The following Tables Eighteen A, B, and
C report a variety of adhesive compositions intended for various
packaging applications, as well as various performance attributes
thereof.
[0237] As illustrated in Tables Eighteen A, B, and C, for high
performance packaging applications, the homogeneous
ethylene/.alpha.-olefin interpolymer employed will have a density
of 0.87 g/cm.sup.3 or less, and a melt index (I.sub.2) of about 500
g/10 min. or less, and will be employed at concentrations of about
30 to 45 weight percent. Preferably, the homogeneous
ethylene/.alpha.-olefin interpolymer will be provided in
combination with from 25 to 45 weight percent of high melt point
wax, and from 20 to 50 weight percent of a high melt point resin.
Example 101 demonstrates the compatibility of the homogeneous
ethylene/alpha-olefin interpolymer with EnBA. This combination is
surmized to be useful for further improving the low temperature
adhesion and thermal stability as well as improve the compatibility
with non-polar tackifying resins. TABLE-US-00024 TABLE EIGHTEEN A
Packaging Adhesives 5342-56-1 5342-56-2 5342-56-3 5342-56-4
5342-56-5 5342-60-1 5342-60-2 5342-60-3 Example 86 Example 87
Example 88 Example 89 Example 90 Example 91 Example 92 Example 93
Dow SM-8400 20 20 22.5 22.5 18 20 20 18 Paraflint H-4 20 25 20 25
17 15 10 10 Eastotac H- 60 55 57.5 52.5 65 65 70 72 100 Irganox
1010 .25 .25 .25 .25 .25 .25 .25 .25 Viscosity @ 151 1270 2280 1140
2315 1865 2705 -- 350.degree. F. (177.degree. C.) (cPs) PAFT
(.degree. F. 158.5 (70) 159 (71) 152 (67) 157.8 (70) 153.8 (68) 163
(73) 153.7 (68) 153 (67) (.degree. C.)) SAFT (.degree. F. 188.2
(87) 192.8 (89) 192.6 (89) 199.8 (93) 185.8 (85) 186.4 (86) 170.4
(77) 160.8 (72) (.degree. C.)) Bonding Testing*: 70.degree. F.
(21.degree. C.) 100 percent 100 percent 100 percent 100 percent 100
percent 100 percent 100 percent 100 percent Clay Coat Surface
Uncoated 85 percent 98 percent 98 percent 75 percent 100 percent 83
percent 80 percent 10 percent Surface 30.degree. F. (-1.degree. C.)
100 percent 100 percent 100 percent 100 percent 100 percent 100
percent 100 percent 100 percent Clay Coat Surface Uncoated 0
percent 100 percent 100 percent 15 percent 70 percent 50 percent 5
percent 0 percent Surface All amounts are reported in weight
percent. *Adhesion to MEAD Carrier-kote (high wet strength),
Average of two bonds - percent fiber tear
[0238] TABLE-US-00025 TABLE EIGHTEEN B Packaging Adhesives
Reference # 5342-521 5342-52-2 5342-52-3 5342-52-4 5342-53-1
5342-53-2 5709-26-1 5709-26-3 5709-26-5 Ex. 94 Ex. 95 Ex. 96 Ex. 97
Ex. 98 Ex. 99 Ex. 100 Ex. 101 Ex. 102 Affinity .TM. SM- 25 28 30 35
30 35 10 10 10 8400 0.87 g/cm.sup.3 I.sub.2 = 200 15 g/10 min** EVA
(18 percent 15 VA, 400 MI) EnBA (35 15 percentBA, 320 MI) Paraflint
H4 20 25 20 20 25 25 25 25 25 Eastotac 55 47 50 45 45 40 50 50 50
H-100-R Irganox 1010 0.2 0.2 0.2 0.2 0.2 0.2 0.3 0.3 0.3 Visc.
@350.degree. F. 3680 cps 4370 cps 5220 cps 8680 cps 4480 cps 7700
cps 1250 cps 1030 cps 840 cps (177.degree. C.) Peel (.degree. F.)
158.5 .+-. 2.72 155.8 .+-. 5.1 160.2 .+-. 5.6 154.8 .+-. 3.3 156.5
.+-. 2.9 159.6 .+-. 5.2 151.6 .+-. 2.0 156.5 .+-. 2.9 148.8 .+-.
1.7 Shear (.degree. F.) 186.4 .+-. 2.99 194.4 .+-. 2.4 188.0 .+-.
1.76 189.2 .+-. 5.6 194.8 .+-. 2.2 193.8 .+-. 2.39 196.2 .+-. 1.6
194.8 .+-. 2.2 195 .+-. 2 Cloud Pt. (.degree. C.) 101 103 102 104
106 102 90 95 95 Open T. (.degree. C.) 75.5 76.1 71.5 78.2 78.1
77.3 78.1 77.3 Set temp (.degree. C.) 61.1 66.3 66.7 63.7 66.1 68.4
66.1 68.4 Bonding Test 70.degree. F. (21.degree. C.) 95 95 100 100
98 99 100 100 100 percent FT percent FT percent FT percent FT
percent FT percent FT percent FT* percent FT* percent FT*
30.degree. F. (-1.degree. C.) 40 80 75 90 85 95 100 100 100 percent
FT percent FT percent FT percent FT percent FT percent FT percent
FT* percent FT* percent FT* Adhesion to Mead Carrier-Kote high wet
strength paperboard (average of two bonds); *Recycled Clay Coated
Boardstock (front/back), 40.degree. F. (4.4.degree. C.) rather than
30.degree. F. (-1.degree. C.); **Substantially linear
ethylene/1-octene interpolymer available from The Dow Chemical
Company
[0239] TABLE-US-00026 TABLE EIGHTEEN C Packaging Adhesives
Reference # Ex. 100 Ex. 101 Ex. 102 Ex. 103 Ex. 104 0.870
g/cm.sup.3 I.sub.2 = 500 g/ 37.3 29.9 39.9 10 min** 0.873
g/cm.sup.3; I.sub.2 = 2200 g/ 35 35 10 min** Affinity .TM. EG- 5 5
8200 0.890 g/cm.sup.3; I.sub.2 = 500 g/ 7.5 10 min** Sylvatac 1103
10 Eastotac 29.9 29.9 29.9 H-130-R Eastotac 25 29.7 H-100-R Bareco
PX-100 29.9 Paraflint H4 32.4 32.4 29.7 Paraffin 155 5 20 Irganox
1010 0.3 0.3 0.3 0.3 0.3 Visc. @350.degree. F. 793 cps 810 cps 961
cps 1056 cps 1386 cps (177.degree. C.) 100 g Peel 131 (55.0) 130
(54.4) 138 (58.9) 119 (48.3) 108 (42.2) (.degree. F. (.degree. C.))
500 g Shear 198 (92.2) 203 (95.0) 200 (93.3) 199 (92.8) 146 (63.3)
(.degree. F. (.degree. C.)) Open T. (.degree. C.) 191 138 Set temp
(.degree. C.) 124 117 Cloud Pt. 205 140 Bonding Test: -40.degree.
F. (-40.degree. C.) 87 percent 50 percent 78 percent 68 percent 84
percent FT FT FT FT FT 0.degree. F. (-17.degree. C.) 81 53 80 67 67
percent FT percent FT percent FT percent FT percent FT 40.degree.
F. (4.4.degree. C.) 88 73 88 93 92 percent FT percent FT percent FT
percent FT percent FT 70.degree. F. (21.degree. C.) 100 percent 91
percent 98 percent 95 percent 87 FT FT FT FT percent FT 102.degree.
F. (38.9.degree. C.) 99 96 99 100 100 percent FT percent FT percent
FT percent FT percent FT Adhesion to hard to bond corrugated,
conditioned for 48 hours
Blends of Homogeneous Ethylene/.alpha.-olefin Interpolymers and
Oil;
[0240] Homogeneous ethylene/.alpha.-olefin interpolymers are
compatible with large quantities of oil, particularly when the
interpolymer has a density of less than 0.880 g/cm.sup.3 and a melt
index (I.sub.2) of 30 g/10 min. or less. The following Tables
Nineteen A-E set forth various blends of homogeneous
ethylene/.alpha.-olefin interpolymers and oil, and representative
performance attributes thereof: TABLE-US-00027 TABLE NINETEEN A
Blends of Oil with a Substantially Linear Ethylene/I-Octene
Interpolymer Having a Density of 0.902 g/cm.sup.3 and an I.sub.2 of
30 g/10 min 33-3 33-4 33-5 33-9 33-10 33-11 Ingredient Ex. 105 Ex.
106 Ex. 107 Ex. 108 Ex. 109 Ex. 110 Affinity .TM. 25 20 17.5 30 35
40 SM-1300 Kaydol Oil 70 70 70 70 70 70 Wt-percent Oil 73.7 77.7 80
70 66.7 63.6 Oil Exudation? yes yes yes yes yes yes
[0241] TABLE-US-00028 TABLE NINETEEN B Blends of Oil with a
Substantially Linear Ethylene/1-Octene Interpolymer Having a
Density of 0.870 g/cm.sup.3 and an I.sub.2 of 30 g/10 min. 33-12
33-13 33-14* 33-15 Ingredient Ex. 111 Ex. 112 Ex. 113 Ex. 114
Affinity .TM. SM-8400 25 30 35 40 Kaydol Oil 70 70 70 70 Wt-percent
Oil 73.7 70.0 66.7 63.6 Oil Exudation? yes yes no no
[0242] TABLE-US-00029 TABLE NINETEEN C Blends of Oil with a
Substantially Linear Ethylene/1-Octene Interpolymer Having a
Density of 0.868 g/cm.sup.3 and an I.sub.2 of 0.5 g/10 min. 22-1
22-2 22-3* 22-4 Ingredient Ex. 115 Ex. 116 Ex. 117 Ex. 118 Affinity
.TM. EG-8150 7 10 15 20 Kaydol Oil 70 70 70 70 Wt-percent Oil 90.9
87.5 82.3 77.8 Oil Exudation? yes yes no no *Denotes lowest amount
of polymer to achieve a non-exuding blend
[0243] TABLE-US-00030 TABLE NINETEEN D Blends of Oil with a
Homogeneous Linear Ethylene/1-Butene Interpolymer Having a Density
of 0.865 g/cm.sup.3 and an I.sub.2 of 10 g/10 min. Ingredient
Reference # Trade 51-1 51-2 51-3 41-1b* 41-2b 41-3b Name Ex. 119
Ex. 120 Ex. 121 Ex. 122 Ex. 123 Ex. 124 SLP-0592 15 20 25 30 35 40
Kaydol Oil 70 70 70 70 70 70 Wt-percent Oil 82.3 77.8 73.7 70.0
66.7 63.6 Oil Exudation? yes yes yes no no no
[0244] TABLE-US-00031 TABLE NINETEEN E Blends of Oil with a
Homogeneous Linear Ethylene/Propylene Interpolymer Having a Density
of 0.865 g/cm.sup.3 and an I.sub.2 of 5 g/10 min. Ingredient
Reference # Trade 51-4 51-5 51-6 41-4b* 41-5b 41-6b Name Ex. 125
Ex. 126 Ex. 127 Ex. 128 Ex. 129 Ex. 130 SLP-0394 15 20 25 30 35 40
Kaydol Oil 70 70 70 70 70 70 Wt-percent Oil 82.3 77.8 73.7 70.0
66.7 63.6 Oil Exudation? yes yes yes no no no *Denotes lowest
amount of polymer to achieve a non-exuding blend
[0245] Examples 105-130 of Tables Nineteen A-E demonstrate the
tremendous oil holding power of homogeneous ethylene/.alpha.-olefin
interpolymers, particularly for homogeneous ethylene/.alpha.-olefin
interpolymers having a density of less than 0.880 g/cm.sup.3 and a
melt index (I.sub.2) of 30 g/10 min. or less. These oil rich blends
exhibit a gel-like character and would be useful for skin
attachment adhesives, particularly when combined with both solid
and/or liquid tackifying resins. Skin attachment adhesive may be
applied to an article by means of slot coating, screen printing and
spraying. Foaming of the adhesive to alter the compliance and
adhesion properties is also contemplated. These gelatinous
compositions are also surmised to have great utility in a variety
of non-adhesive applications.
Adhesives Comprising Homogeneous Ethylene/.alpha.-Olefin
Interpolymers and Polyamides
[0246] The adhesives of the invention may further comprise one or
more polyamides. Representative hot melt adhesives comprising a
homogeneous ethylenel.alpha.-olefin interpolymer and a polyamide,
as well as representative performance attributes thereof, are set
forth in the following Tables Twenty A and B.
[0247] Examples 131-143 yielded transparent, single phase adhesive
compositions demonstrating the compatibility of the homogeneous
ethylene/.alpha.-olefin interpolymer with polyamides. All
formulations yielded moderately high tack levels initially.
Examples 133, 134, 135 and 136 were found to maintain moderate tack
levels even after 72 hours of heat history. It is unexpected that
the high softening point polyamides do not detract from the
pressure sensitivity. Accordingly, the polyamides can be added to
boost the performance of PSAs by increasing the heat resistance,
creep resistances, and/or plasticizer resistance. TABLE-US-00032
TABLE TWENTY A Adhesives Comprising a Homogeneous
Ethylene/.alpha.-Olefin Interpolymer/Polyamide Blends 13-1 13-2
13-3 13-4 14-1 14-2 26-1 26-2 Ingredient Ex. 131 Ex. 132 Ex. 133
Ex. 134 Ex. 135 Ex. 136 Ex. 137 Ex. 138 Affinity .TM. EG- 25 30 25
25 30 30 8200 Affinity .TM. EG- 25 30 8150 Kaydol Oil 30 35 30 30
35 35 30 35 Eastman H-130 55 45 45 45 35 35 30 20 Polyamide 10 10
15 15 HL-6088 Polyamide 10 10 HL-2660 Irganox 1010 0.3 0.3 0.3 0.3
0.3 0.3 0.3 0.3 Viscosity @ 350.degree. F. 13000 20050 18600 17100
32150 30200 (177.degree. C.)(cps) Gel Not Tested no no no no Not
Tested Skin '' '' no slight no slight '' '' Color '' '' amber dark
amber amber dark amber '' '' Separation '' '' no no no no '' ''
[0248] TABLE-US-00033 TABLE TWENTY B Adhesives Comprising a
Homogeneous Ethylene/.alpha.-Olefin Interpolymer/Polyamide Blends
38-1 44-1 44-2 44-3 44-4 Ingredient Ex. 139 Ex. 140 Ex. 141 Ex. 142
Ex. 143 EIP #4 35 25 20 15 22.5 Kaydol Oil 25 25 25 25 25 Eastotac
40 40 40 40 37.5 H-100 Polyamide 10 15 20 15 HL-2660 (H.B. Fuller)
Viscosity @ 22500 9600 6400 3480 9000 350.degree. F. (cps)
Appearance clear hazy hazy hazy hazy (Molten) Finger Tack high high
high high high Adhesion high high high high not tested Initial
(Resistance) Adhesion moderate high high high not tested Aged 24
hrs/140.degree. F. (60.degree. C.) (Resistance) Separation no no no
slight no Gel no no no gel no Char no moderate moderate moderate
moderate
Insulation Bonding
[0249] The adhesives of the present invention may find further
utility in insulation bonding. The following Table Twenty-One sets
forth representative examples of such formulations, and
representative performance attributes thereof: TABLE-US-00034 TABLE
TWENTY ONE Hot Melt Adhesives for Insulation Bonding Ex. 144 Ex.
145 0.890 g/cm.sup.3; I.sub.2 = 2200 69.5 g/10 min** 0.890
g/cm.sup.3; I.sub.2 = 200 30.5 g/10 min** Eastotac H-130R 30.0 44.5
Escorez 5400 Polybutene M.sub.w 1300 10.0 Benzoflex 352 10.0
Irganox 1010 0.5 0.5 Visc. @ 350.degree. F. (177.degree. C.) 2680
cps 1975 cps SAFT (.degree. F. (.degree. C.)) 182 (83) 166 (74)
PAFT (.degree. F. (.degree. C.)) 126 (52) 132 (56) Open time less
than 20 sec. Less than 30-45 sec. **Homogeneous ethylene/1-octene
interpolymers available from The Dow Chemical Company
[0250] The above examples have been provided for the purpose of
exemplification, rather than limitation. One skilled in the art
will appreciate that the hot melt adhesives of the invention may be
readily adapted for various applications. Accordingly, the
invention shall be determined in accordance with the scope of the
following claims:
* * * * *