Thermoplastic compositions comprising crystalline water soluble polymers and amorphous water sensitive polymers

The present invention relates to a thermoplastic composition comprising at least one crystalline water sensitive polymer and at least one amorphous water sensitive polymer. The thermoplastic composition may optionally further comprise additional ingredients such as other polymers, tackifying resins, plasticizers, waxes, and mixtures thereof. The thermoplastic compositions are useful in a variety of applications wherein water or moisture sensitive thermoplastic materials are employed such as various packaging adhesive applications including case and carton sealing, remoistenable adhesives, repulpable/recyclable adhesives and multiwall bag applications. The present invention is also useful for moisture activatable reinforcement strings and opening tapes for corrugated containers, as well as for a variety of nonwoven applications such as body fluid impermeable barriers, core stabilization adhesives, and construction adhesives.

FIELD OF THE INVENTION 
The present invention relates to a thermoplastic composition comprising at 
least one crystalline water sensitive polymer and at least one amorphous 
water sensitive polymer. The thermoplastic composition may optionally 
further comprise additional ingredients such as other polymers, tackifying 
resins, plasticizers, waxes, and mixtures thereof. The thermoplastic 
compositions are useful in a variety of applications wherein water or 
moisture sensitive thermoplastic materials are employed such as various 
packaging adhesive applications including case and carton sealing, 
remoistenable adhesives, repulpable/recyclable adhesives and multiwall bag 
applications. The present invention is also useful for moisture 
activatable reinforcement strings and opening tapes for corrugated 
containers, as well as for a variety of nonwoven applications such as body 
fluid impermeable barriers, core stabilization adhesives, and construction 
adhesives. 
BACKGROUND OF THE INVENTION 
Several patents are directed to water soluble polyamides. U.S. Pat. No. 
3,882,090 to Fagerberg et al., issued May 6, 1975 relates to linear 
water-soluble polyamides having ether linkages in the polymer chain. The 
polyamides are useful as textile sizing agents, coatings, adhesives and 
water soluble films. 
U.S. Pat. No. 5,053,484 to Speranza et al., issued Oct. 1, 1991 relates to 
polyether amides produced by reacting a polyethylene glycol diamine and a 
first dicarboxylic acid or an ester thereof, with a polyoxyalkylene 
diamine of a molecular weight of at least 500 and a second dicarboxylic 
acid or an ester thereof. 
U.S. Pat. No. 5,118,785 to Speranza et al., issued Jun. 2, 1992 relates to 
polyether amides produced by reacting aromatic dicarboxylic acids with 
tetraethylene glycol diamine. The resulting polyether amides are useful to 
make polymers and fiber, with unusually good water absorbency properties. 
U.S. Pat. No. 5,086,162 to Speranza et al., issued Jun. 28, 1994 relates to 
polyether amides produced by reacting at least one polyoxyalkylene glycol 
diamine with at least two different carboxylic acid or esters thereof The 
polyamides exhibit improved water absorbency, and/or solubility in water. 
U.S. Pat. No. 5,324,812 to Speranza et al., issued Jun. 28, 1994 relates to 
water soluble polyamides produced by reacting two different carboxylic 
acids with at least one low molecular weight poly(alkylene glycol) diamine 
and at least one relatively high molecular weight polyoxyalkylene diamine. 
Such water soluble polyamides are taught to be useful in hot melt adhesive 
formulations. 
Collectively, the polyamides taught in Speranza either exhibit a high melt 
point, or in the case of those polyamides having lower melt points, are 
disadvantageous in that the polyamides tend to block once formed into an 
adhesive. 
WO 96/08538, published Mar. 21, 1996 is directed to a remoistenable 
adhesive wherein the remoistenable adhesive is a hot melt consisting of a 
water soluble polyamide. The water soluble polyamide may be optionally 
combined with a tackifier or wax. 
Although water soluble polyamides have been identified for use as 
remoistenable adhesives, such class of polymers tend to disadvantageously 
have a high melt point, relatively high molten viscosity and slow speed of 
remoistening. Attempts to reduce the melt point and viscosity by means of 
formulating the polyamides with conventional hot melt adhesive additives 
such as tackifiers and waxes often results in diminished blocking 
resistance. Hence, industry would find advantage in water sensitive 
adhesive compositions having a low viscosity, fast rate of remoistening, 
that also possess the desired blocking resistance. 
SUMMARY OF THE INVENTION 
The applicants have found that by combining crystalline water sensitive 
thermoplastic materials with amorphous water sensitive thermoplastic 
materials, the properties of the mixture exhibit a synergistic 
improvement. The resulting mixture exhibits improved melt processability 
characteristics and improved rate of moistenability with respect to a 
composition based on crystalline water sensitive polymer, in addition to 
exhibiting excellent humidity and blocking resistance. 
The thermoplastic composition of the present invention comprises at least 
one crystalline water sensitive thermoplastic polymer blended with at 
least one amorphous water sensitive thermoplastic polymer. The at least 
one crystalline water sensitive thermoplastic material useful in the 
present invention is preferably a water soluble or water dispersible 
polyamide. The at least one amorphous water sensitive thermoplastic 
material useful in the present invention includes such polymers as 
polyvinyl alcohol (PVOH), polyvinyl pyrrolidone (PVP), polyvinyl 
pyrrolidone/vinyl acetate (PVP/VA), polyvinyl pyrrolidone/acrylic acid, 
polyoxazoline (PEOX), and preferably, linear and branched water 
dispersible polyesters (EASTMAN AQ), and mixtures thereof. 
In a preferred embodiment, the thermoplastic composition comprises: 
a) from about 10 wt-% to about 90 wt-% of at least one crystalline water 
sensitive thermoplastic polymer; 
b) from about 10 wt-% to about 90 wt-% of at least one amorphous water 
sensitive thermoplastic polymer; 
c) 0 to about 30 wt-% of at least one wax. 
In another embodiment, the present invention relates to an improved 
remoistenable adhesive composition comprising: 
a) from about 10 wt-% to about 90 wt-% in the adhesive of at least one 
crystalline water sensitive thermoplastic polymer; 
b) from about 20 wt-% to about 60 wt-% in the adhesive of at least one 
amorphous water sensitive thermoplastic polymer; 
c) 0 to about 30 wt-% in the adhesive of at least one wax. 
The present invention also relates to a body fluid impermeable article 
comprising a body fluid permeable substrate coated with a thermoplastic 
composition comprising: 
a) from about 10 wt-% to about 90 wt-% of at least one crystalline water 
sensitive thermoplastic polymer; 
b) from about 10 wt-% to about 90 wt-% of at least one amorphous water 
sensitive thermoplastic polymer; 
c) 0 to about 30 wt-% of at least one wax. 
Preferably, the body fluid impermeable barrier layer or the entire article 
is dispersible in tap water, yet maintains its integrity in the presence 
of body fluids. 
DETAILED DESCRIPTION OF THE INVENTION 
The term "water sensitive" means soluble, dispersible and/or swellable in 
an aqueous environment. In the case of repulpable applications, water 
soluble or water dispersible materials rather than merely swellable are 
preferred. 
The term "crystalline polymer" means those polymers which retain their 
rubbery elastomeric or flexible properties above the glass transition, 
until the melting temperature has been surpassed. Melting is also 
accompanied by a loss of crystalline X-ray diffraction effects. 
The term "amorphous" means those materials, that as the temperature is 
raised, gradually give way to a soft, extensible elastomeric phase, then 
to a gum and finally to a liquid. No sharp transition occurs from one 
phase to the other. 
The term "polymer" refers to a component having a Mw greater than about 
3000. 
The present invention is a thermoplastic composition comprising at least 
one crystalline ingredient and at least one amorphous ingredient. The 
total amount of water sensitive ingredients in the composition is at least 
50 wt-%. The crystalline ingredient is a water sensitive, preferably water 
soluble or water dispersible thermoplastic polymer. The concentration of 
the crystalline polymer is a function of the percent crystallinity which 
can be measured by Wide Angle X-Ray Scattering methods used for waxes. In 
general, the crystalline water sensitive thermoplastic polymer is present 
in an amount ranging from about 10 wt-% to about 90 wt-%, preferably from 
about 15 wt-% to about 80 wt-%, more preferably from about 15 wt-% to 
about 75 wt-%, and most preferably from about 20 wt-% to about 60 wt-%. 
The ratio of crystalline water sensitive polymer to amorphous water 
sensitive polymer ranges from 1:2 to 2:1 and preferably is about 1:1. 
However, if the crystallinity of the polymer is significantly greater than 
50%, for example about 70% or greater, lower concentrations of crystalline 
polymer may be employed. In contrast, higher concentrations are useful if 
the percent crystallinity is less than about 30%. The crystalline 
component contributes to the blocking resistance and humidity resistance 
as well as improves the rate of set. 
One particularly preferred class of crystalline water sensitive 
thermoplastic polymers are water soluble polyamides. Such polyamides are 
the reaction product of at least one polyoxyalkylene diamine with at least 
one dicarboxylic acid or esters thereof. 
The polyoxyalkylene glycol diamine has the formula: 
EQU NH.sub.2 --(CH.sub.2).sub.x --(OCH.sub.2 --CH.sub.2).sub.y 
--O--(CH.sub.2).sub.x --NH.sub.2 
wherein X ranges from 2 to 3 and Y ranges from 1 to 2. 
Representative examples include triethylene glycol diamine, wherein X=2 and 
Y =1, and tetraethylene glycol diamine, wherein X=2 and Y=2. Commercial 
diamines include Jeffamine.RTM. XTJ-504 amine and Jeffamine.RTM. EDR-192 
amine available from Huntsman Chemical Co., Houston, Tex. A preferred 
diamine is 4,7,10-trioxatridecane-1,13-diamine (TTD diamine) available 
from BASF, Parsippany, N.J., wherein X=3 and Y=2. Other amines such as 
Jeffamine.RTM. D-230, D-400, XTJ-500, XTJ-501 and XTJ-502 are also useful 
provided a chain terminator acid or amine is employed during the reaction, 
and/or additional ingredients such as waxes, tackifiers, crystalline 
polymers, and monoacids are subsequently combined with the reacted 
polyamide. For example, when adipic acid is reacted with TTD diamine and 
Jeffamine.RTM. D-230, the resulting polyamide is relatively slow setting 
with respect to reacting adipic acid with TTD diamine alone. 
The polyoxyalkylene diamine is reacted with an equal stochiometric ratio of 
a dicarboxylic acid. Suitable dicarboxylic acids are those having from 5 
to 36 carbon atoms including adipic acid, pimelic acid, azelaic acid, 
sebacic acid, suberic acid, dodecanedioic acid, terephthalic acid, 
isophthalic acid, t-butyl isophthalic acid, dimer acid and mixtures 
thereof. The esters and anhydrides of these acids may also be used. Adipic 
acid is preferred. 
The resulting water soluble polyether amide preferably has a melt point 
about 190.degree. C. or less as in the case when adipic acid is reacted 
with Jeffamine.RTM. XTJ-504. More preferably, the melt point is about 
155.degree. C. or less as in the case when adipic acid is reacted with 
Jeffamine.RTM. EDR-192. The most preferred water soluble polyether amide 
has a melt point about 150.degree. C. or less as in the case when adipic 
acid is reacted with TTD diamine. This particular combination results in a 
faster setting, strong, easily processed water soluble polyether amide. 
The low melt temperature makes this combination particularly attractive 
for low application temperature applied remoistenable hot melt adhesives 
having an application temperature less than 177.degree. C. For 
remoistenable adhesive, it is also preferable that the molten viscosity of 
the polyamide be less than about 2,000 cPs at 177.degree. C. 
The applicants have found that certain polyamides are preferred due to 
their contribution to the nonblocking and humidity resistant properties. 
Polyamides exhibiting such properties are those which are produced by 
reacting polyoxyalkylene diamine with at least one dicarboxylic acid or an 
ester thereof, the polyoxyalkylene diamine having the formula: 
EQU NH.sub.2 --(CH.sub.2).sub.3 --(OCH.sub.2 --CH.sub.2).sub.2 
--O--(CH.sub.2).sub.3 --NH.sub.2. 
In this embodiment, adipic acid is the preferred dicarboxylic acid. 
However, other diacids may also be employed provided the mole percent of 
the additional diacids is about 10 mole percent or less with respect to 
the total acid content. When an additional diacid is employed at a 
concentration greater than about 10 mole percent, particularly at about 25 
mole percent or greater with respect to the total diacid content, the 
resulting polyamide exhibits a longer set time prior to becoming 
completely non-blocking. Accordingly, it is often desirable to add an 
additional ingredient to increase the rate of set as described in further 
embodiments as follows. 
Additionally, other water soluble polyamides contribute comparable humidity 
and blocking resistance provided a chain terminator is employed during the 
reaction and/or the polyamide is further combined with at least one 
additional ingredient including waxes, solid tackifiers, monocarboxylic 
acids, and crystalline polymers. In these embodiments, the polyamide is 
produced by reacting at least one polyoxyalkylene diamine with 
dicarboxylic acid or an ester thereof, said polyoxyalkylene diamine having 
the formula: 
EQU NH.sub.2 --(CH.sub.2).sub.x --(OCH.sub.2 
--CH.sub.2).sub.y--O--(CH.sub.2).sub.x --NH.sub.2 
wherein X ranges from 2 to 3 and Y ranges from 1 to 2. 
Chain terminators include monoacids and/or monoamines and are useful in an 
amount less than about 5 wt-%, preferably from about 0.5 wt-% to about 2.5 
wt-% based on total acid weight to control the molecular weight. 
Representative examples of useful monocarboxylic acids include stearic 
acid, benzoic acid and montannic acid such as Wax S available from Hoechst 
Celanese. In the absence of a chain terminator, the resulting polyamide, 
particularly those taught by Speranza in U.S. Pat. Nos. 5,053,484, 
5,086,162, 5,324,812, and 5,118,785 are deficient in at least one property 
including exhibiting a high melt point, slow rate of set, high viscosity, 
poor humidity resistance and/or poor blocking resistance. 
In addition or in the alternative, the polyamide component may be combined 
with at least one ingredient selected from the group consisting of waxes, 
tackifiers, crystalline polymers, monocarboxylic acids and mixtures 
thereof. The monocarboxylic acids and monoamines have been found to be 
useful not only as a reactant as previously described but also as an 
ingredient to be added after the polyamide is formed. 
NP-2126 as well as other grades of water soluble or water dispersible 
polyamides are commercially available from H.B. Fuller Company (St. Paul, 
Minn.). 
Although water soluble and water dispersible polyamides are the preferred 
water soluble crystalline material to be employed in the present 
invention, the applicants surmise other crystalline water sensitive 
polymers such as polyethylene oxide available from Union Carbide (Danbury, 
Conn.) and crystalline polyesters may also be suitable. Water sensitive 
polymers that can be synthesized to possess similar physical properties 
such as viscosity and extent of crystallinity to that of the exemplary 
polyamides are believed to be particularly useful. 
In addition to the water sensitive crystalline component, the thermoplastic 
composition of the present invention comprises at least one amorphous 
water sensitive thermoplastic polymer. The amorphous water sensitive 
thermoplastic polymer is present in an amount ranging from about 10 wt-% 
to about 90 wt-%, preferably from about 15 wt-% to about 80 wt-%, more 
preferably from about 15 wt-% to about 70 wt-%, and more preferably from 
about 15 wt-% to about 60 wt-%. The concentration of amorphous water 
sensitive polymer employed is a function of molecular weight and glass 
transition temperature (Tg). In general, higher amounts of amorphous 
polymers may be employed when the amorphous polymer selected has a 
relatively high Tg, for example from about 15-20.degree. C., or greater. 
In contrast, lower concentrations of amorphous polymers are employed when 
the amorphous polymer selected has a relatively low Tg, for example less 
than 0.degree. C. For high molecular weight amorphous polymers, those 
having a Brookfield molten viscosity greater than about 50,000 cPs, 
generally lower amounts of amorphous polymer are employed, whereas higher 
amounts are useful for low molecular weight polymers. The amorphous water 
sensitive material increases the speed of remoistening and improves the 
bond strength to the extent that full-fiber tearing bonds are achieved 
both initially and maintained thereafter. 
Amorphous water sensitive thermoplastic polymers contemplated for use in 
the present invention include such polymers as polyvinyl alcohol (PVOH) 
available from Nippon Grohsei (Japan) such as GROHSERAN L-301 and 
GROHSERAN L-302 and UNITIKA available from Unitaka Ltd. (Japan); polyvinyl 
pyrrolidone (PVP) available from BASF (Mount Olive, N.J.) and ISP (Wayne, 
N.J.); polyvinyl pyrrolidone/vinyl acetate copolymer (PVP/VA) and 
polyvinyl pyrrolidone/acrylic acid such as ACRYLIDONE, both available from 
ISP; polyethyloxazoline available from The Dow Chemical Company (Freeport, 
Tex.) under the tradename PEOX and from PCI Incorporated (Tucson, Ariz.) 
under the tradename AQUAZOL, polyvinyl methyl ether available from Amoco 
Chemical Co. under the tradename AMOBOND, linear polyesters, 
polyacrylamide and preferably water dispersible polyesters and 
copolyesters (EASTMAN AQ) and amorphous water soluble and water 
dispersible polyamides. 
One particularly preferred class of amorphous water sensitive thermoplastic 
polymers is water dispersible polyesters and copolyesters available from 
Eastman Chemical Company (Kingsport, Tenn.) under the tradename EASTMAN 
AQ. These water dispersible polymers are linear polyesters or branched 
copolyesters containing sulfonomer. Such polymers are saline and body 
fluid insoluble, yet dispersible in tap water. The Tg of the branched 
water dispersible copolyesters ranges from about -5.degree. C. to 
7.degree. C., whereas the linear polyesters have a Tg from about 
30.degree. C. to about 60.degree. C. Commercial examples of solid 
thermoplastic linear water dispersible polyesters include AQ 35S (7,000 
Mn), AQ 38S (10,000 Mn), and AQ 55S(8,000 Mn). 
Preferred water dispersible copolyesters are those which are branched and 
exhibit an intrinsic viscosity of about 0.6 IV (EASTMAN AQ-14000) or less, 
more preferably about 0.4 IV (EASTMAN AQ-1950) or less, even more 
preferably about 0.3 IV (EASTMAN AQ-1350) or less, and most preferably, 
particularly for low application temperature remoistenable adhesives, 0.2 
IV (EASTMAN AQ-1045) or less. In terms of molten viscosity, these ranges 
correlate to a Brookfield viscosity ranging from about 5,000 to about 
40,000 cPs. Higher viscosity versions may also be employed for 
compositions intended for applications where a low molten viscosity is not 
required such as for reinforcement tapes and strings as well as fibers. 
Information relating to the chemical synthesis of the branched polyesters 
may be found in U.S. Pat. Nos. 5,543,488 and 5,552,495, incorporated 
herein by reference. Lighter color and low odor modifications of such 
water dispersible copolyester are also contemplated, particularly for 
nonwoven applications in which odor and color tend to be important 
characteristics. 
The thermoplastic composition of the present invention also preferably 
comprises a wax in an amount up to about 30 wt-%, more preferably at an 
amount ranging from about 3 wt-% to about 20 wt-%, and most preferably 
from about 5 wt-% to about 15 wt-%. Waxes useful herein are preferably 
polar in nature. Polar waxes are those which contain at least one polar 
functional group such as hydroxyl, amide, sulfone, phosphate, sulfonamide, 
urethane, carboxylate acid, amine, and carbonate. The concentration of the 
functional group is present in an amount greater than about 
2.times.10.sup.-3 equivalents per gram and preferably greater than 
3.5.times.10.sup.-3 equivalents per gram. The molecular weight of waxes 
ranges from about 200 g/mole to about 1000 g/mole. Representative examples 
including 12-hydroxystearamide, N-(2-hydroxy ethyl 12-hydroxystearamide 
and N,N' ethylene bis 12-hydroxystearamide (ICIN 220 and ICIN 285 
respectively, from CasChem, Bayonne, N.J.), stearamide (KEMAMIDE S from 
Witco, Memphis, Tenn.), glycerin monostearate, sorbitan monostearate, and 
12-hydroxy stearic acid. Also useful alone or in combination with the 
above are less polar waxes such as N,N'-ethylene-bis stearamide (KEMAMIDE 
W-40 from Witco), linear aliphatic long chain alcohols (UNILIN 425 from 
Petrolite, Tulsa, Okla.), hydrogenated castor oil (castor wax), oxidized 
synthetic waxes, and functionalized waxes such as oxidized homopolymers 
and oxidized polyethylene waxes (PETROLITE E-1040). The Applicants have 
found that polar waxes having a melt point greater than 70.degree. C., 
preferably greater than about 110.degree. C., and more preferably about 
140.degree. C. or greater, are particularly advantageous. 
The thermoplastic composition of the present invention also preferably 
comprises a plasticizer in an amount up to about 10 wt-% and preferably in 
an amount ranging from about 1 wt-% to about 5 wt-%. Surprisingly, as 
little as about 3 wt-% of plasticizer improves the compatibility of the 
ingredients. Preferred compatible plasticizers include natural and polar 
liquid plasticizers including phthalate plasticizers such as dioctyl 
phthalate and butyl benzyl phthalate (e.g., SANTICIZER 160 from Monsanto, 
St. Louis, Mo.); liquid polyesters such as DYNACOL 720 from Huls and 
liquid polymeric plasticizer available from CP. Hall, Chicago, Ill.; 
benzoate plasticizers such as 1,4-cyclohexane dimethanol dibenzoate (e.g., 
BENZOFLEX 352 from Velsicol, Rosemont, Ill.), diethylene 
glycol/dipropylene glycol dibenzoate (e.g., BENZOFLEX 50 from Velsicol), 
dipropylene glycol dibenzoate (e.g., BENZOFLEX 9-88 from Velsicol), 
polypropylene glycol dibenzoate (e.g., BENZOFLEX 400 from Velsicol), and 
diethylene glycol dibenzoate where the mole fraction of hydroxyl groups 
which have been esterified ranges from 0.5 to 0.95 (e.g., BENZOFLEX 2-45 
High Hydroxyl also from Velsicol); phosphite plasticizers such as t-butyl 
diphenyl phosphate (e.g., SANTICIZER 154 from Monsanto); polyethylene 
glycol having a molecular weight below about 1000 and derivatives of 
polyethylene glycol including PYCAL 94, the phenyl ether of PEG available 
from ICI (Wilmington, Del.); ethoxylated bis phenol A (e.g., MACOL 206 EM 
from PPG Industries, Pittsburgh, Pa.); dionyl phenol ethyoxylates (e.g., 
Surfonic DNP from Huntsman Chemical Corp.); liquid rosin derivatives 
having Ring and Ball softening points below about 60.degree. C. such as 
methyl ester of hydrogenated rosin (e.g., HERCOLYN D from Hercules, 
Wilmington, Del.); as well as vegetable and animal oils such as glycerol 
esters of fatty acids and polymerizable products thereof. Preferred 
plasticizers include phenyl ether of PEG, butyl benzyl phthalate, toluene 
sulfonamide (UNIPLEX 214 from Unitex Chemical Corp, Greensboro, N.C.), 
acetyl-tributyl citrate (CITROPLEX A-4, Moreflex Inc, Greensboro, N.C.), 
benzoate plasticizers such as 1,4-cyclohexane dimethanol dibenzoate, 
diethylene glycol/dipropylene glycol dibenzoate, and diethylene glycol 
dibenzoate where the mole fraction of hydroxyl groups which have been 
esterified ranges from 0.5 to 0.95. 
A variety of other polymers, tackifiers and additives such as antioxidants 
(IRGANOX 1010), pigments and fillers, particularly hydrophilic fillers 
such as starch or cellulose esters and acetates, may be employed in an 
amount up to about 10 wt-% provided such materials do not detract from the 
humidity resistance, blocking resistance and speed of moistenability 
contributed by the blend of crystalline water sensitive polymer with 
amorphous water sensitive polymer. 
The composition of the present invention may further comprise additional 
thermoplastic polymers. Such polymers may be amorphous or crystalline and 
need not be water sensitive. Representative examples include 
ethylene-vinyl acetate copolymers containing about 12% to about 50% vinyl 
acetate, ethylene acrylic acid, ethylene methyl acrylate and ethylene 
n-butyl acrylate copolymers as well as polylactide, caprolactone polymers, 
and poly (hydroxy-butyrate/hydroxyvalerate), polyvinyl alcohol, linear 
saturated polyesters such as DYNAPOL or DYNACOLL polymers from Creanova 
Inc, (Piscataway, N.J.), poly(ethylene oxide)polyether amide and polyester 
ether block copolymers available from Elf Atochem (Birdsboro, Pa.) as 
PEBAX or Hoechst Celanese (Dallas, Tex.) as RITE-FLEX respectively, and 
polyamide polymers such as those available as (UNIREZ) from Union Camp 
(Savannah, Ga.), Huls as VESTAMELT or EMS-Chemie, Sumter, S.C. as 
GRILTEX). 
The thermoplastic composition of the present invention may comprise 
tackifying resins. The tackifying resins useful herein are generally polar 
in nature and have a Ring & Ball softening point greater than 60.degree. 
C. and include any compatible resins or mixtures thereof such as natural 
and modified rosins such as gum rosin, wood rosin, tall oil rosin, 
distilled rosin, hydrogenated rosin, dimerized rosin, and polymerized 
rosin; rosin esters such as glycerol and pentaerythritol esters of natural 
and modified rosins such as, for example, the glycerol ester of pale, wood 
rosin, and the glycerol ester of hydrogenated rosin, the glycerol ester of 
polymerized rosin, and the pentaerythritol ester of hydrogenated rosin, 
and the phenolic-modified pentaerythritol ester of rosin; phenolic 
modified terpene or alpha methyl styrene resins as well as the 
hydrogenated derivatives thereof such as the resin product resulting from 
the condensation in an acidic medium of a bicyclic terpene and a phenol. 
Representative examples of preferred tackifiers include FORAL NC, KRISTALEX 
and ENDEX available from Hercules (Wilmington, Del.); non-ionic materials 
such as FORAL AX also from Hercules, alpha methyl styrene phenolics such 
as URATAK 68520 from DSM Resins (Panama City, Fla.), rosin esters such as 
UNITAC R100L available from Union Camp, terpene phenolic tackifiers such 
as NIREZ 300 and NIREZ V2040 available from Arizona Chemical (Panama City, 
Fla.). 
The Applicants have found that by employing a blend of amorphous and 
crystalline water sensitive materials, a synergistic improvement in the 
adhesive performance is achieved. In general, the blocking and humidity 
resistance is improved by the presence of the crystalline component, 
whereas the rate of remoistening is enhanced by the presence of the 
amorphous component. In the preferred embodiments the blocking and 
humidity resistance is comparable to a composition based on crystalline 
water sensitive polymer alone. 
The thermoplastic composition of the present invention is useful for a 
variety of applications including packaging adhesive applications such as 
case and carton sealing, remoistenable adhesives, repulpable/recyclable 
adhesives and multiwall bag applications; moisture activated reinforcement 
strings/tapes and opening tapes for corrugated containers; as well as for 
a variety of nonwoven applications such as for body fluid insoluble 
barrier film layers, core stabilization adhesives, construction adhesives 
for bonding nonwoven, absorbent(s) and films and super absorbent fixation. 
The terminology "remoistenable" adhesive arose from the fact that the first 
classes of adhesives that were used in this fashion were water-based. The 
adhesive was applied to an envelope, stamp, packing tape, sticker or 
label, in an aqueous form and dried, resulting in a non-tacky adhesive 
layer. Subsequently, the adhesive was activated by remoistening the 
adhesive. Several of these water-based adhesives have been replaced by 
water or moisture activatable hot melt adhesives. In contrast, the hot 
melt adhesives are applied molten. Although technically the adhesive is 
not remoistened, in that the adhesive was never "wet" in the first place, 
these applications continue to be described as remoistenable adhesive 
applications. 
For remoistenable applications, the thermoplastic composition preferably 
has the following properties: 
______________________________________ 
Brookfield Viscosity 
&lt;2,000 cPs at 350.degree. F. (177.degree. C.) 
and &lt;1,000 cPs at 350.degree. F. 
(177.degree. C.) for low application 
temperatures 
Rate of Remoistening &lt;30 seconds 
Bond Strength 100% fiber tear 
Blocking @ Room Temperature Good 
Blocking at 90% RH/85.degree. F. (29.degree. C.), Good 
preferably at 90% RH/100.degree.F. (38.degree. C.) 
______________________________________ 
The adhesive compositions of the present invention are repulpable making 
them amenable for bonding recyclable paper and corrugated for labeling, 
case and carton sealing applications as well as paper recyclable bags such 
as multi-wall bags and "beater bag" end-sealing applications. Beater bags 
are large paper bags filled with additives used in the paper manufacturing 
industry. The entire bag is added to the pulp mixture slurry when making 
paper. 
The thermoplastic composition of the present invention is also useful as a 
reinforcement string as well as for tear opening tape systems for 
corrugated packages or cartons. These types of tapes or strings currently 
comprise a hydrophobic hot melt adhesive. The tapes or strings are 
positioned between the layers of corrugated material and then heat 
activated, to secure them in place. The temperature and duration of time 
the corrugated materials are exposed to heat varies greatly with each 
converter. Therefore, a wide variety of tapes and strings are needed 
wherein the open time, melt temperature, and viscosity of the hot melt 
adhesives is tailored for the specific needs of the converter. The present 
invention provides a "universal" string or tape that is moisture activated 
rather than heat activated eliminating the need to produce a wide variety 
of tapes and strings. The thermoplastic composition of the present 
invention is applied to a fiber substrate core comprising such materials 
as rayon, polyester and cotton as well as other synthetic and natural 
fibers. Depending on the dimensions of the core, a tape or string is 
produced. The tape or string can advantageously be wound up into a 
roll-good, due to the excellent humidity resistance and blocking 
resistance provided by the polyamide. During the conversion of paper board 
into corrugated containers residual moisture is driven off. The residual 
moisture rather than the heat activates the adhesive, adhering the tape or 
string in place. In case of reinforcement tapes or strings or "tear tape 
opening systems" as described in U.S. Pat. No. 5,098,757, incorporated 
herein by reference, the properties of the moisture activatable 
thermoplastic composition are surmised to be near the same as for the 
remoistenable adhesive composition with the exception that a wide range of 
molten viscosities are tolerable, ranging from about 1,000 cPs to about 
30,000 cPs at 177.degree. C., and preferably from about 4,000 cPs to about 
30,000 cPs. 
The present invention is also useful for a variety of nonwoven 
applications, the subject matter of copending patent application Ser. No. 
08/562,038 which corresponds to EP Serial No. 96/118466.0, published Jul. 
2, 1997, incorporated herein by reference. Nonwoven applications include 
forming a (body) fluid impermeable barrier layer by coating the 
thermoplastic composition of the present invention onto a carrier material 
such as nonwoven or paper; construction applications wherein a nonwoven, 
film, elastomeric, material, or absorbent is bonded to at least one other 
substrate by means of an adhesive; core stabilization wherein adhesive is 
applied to fibrous pulp to enhance the tear strength or wet strength of 
the pulp, and superabsorbent polymer fixation wherein particles of SAP are 
bonded to a substrate. The formation of films in-line by coating a 
substrate with the inventive thermoplastic composition is of particular 
interest for manufacturing flushable absorbent disposable products such as 
sanitary napkins. The thermoplastic composition may be used to form a 
continuous film in a single application by non-contact slot coating of the 
inventive thermoplastic composition or by multiple applications. To reduce 
costs, preferably the composition is coated at low basis weight ranging 
from about 10 g/m.sup.2 to about 50 g/m.sup.2 and more preferably from 
about 10 g/m.sup.2 to about 25 g/m.sup.2. Alternatively, due to the water 
solubility of embodiments of the present invention, the composition can be 
dispersible in water and coated onto a water permeable substrate in 
aqueous form. A variety of disposable articles can be formed including 
disposable diapers and training pants, adult incontinent devices, sanitary 
napkins and pantiliners, surgical drapes and gowns, and the like. For 
flushable articles, the thermoplastic composition is preferably tap water 
soluble, yet body fluid insoluble. 
The invention is further illustrated by the following non-limiting 
examples:

EXAMPLES 
Test Methods: 
1. 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-27 hot-melt spindle, suitable 
for measuring viscosities in the range of from 10 to 100,000 centipoise. 
The sample is placed in the chamber, which is in turn inserted into a 
Brookfield Thermosel and locked into place. 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 the desired temperature, 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. 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. 
2. Blocking Resistance is determined by preparing a coating on a sheet of 
20 lbs. (9 kg) bleached Kraft paper (standard copy paper) with the 
thermoplastic composition at a thickness ranging from about 0.6 to 1 mil 
(0.002 cm to 0.003 cm) using a suitable coating device or draw-down 
technique. The coated paper is then cut into 1 inch (2.5 cm) strips and 
conditioned at 50% relative humidity for two hours. At least three strips 
of the coated paper are placed on a tray and a piece of paper placed on 
top, sandwiching the thermoplastic composition between two paper layers. A 
500 g weight is place on top of each strip resulting in a force of 
500g/sq. inch and the tray is placed in a 140.degree. F. (60.degree. C.) 
oven for 24 hours. After 24 hours, the uncoated paper is removed noting 
the extent of thermoplastic composition sticking or picking to the 
uncoated paper. The extent of blocking is characterized as follows: 
"excellent"--no picking, paper falls from polyamide without resistance 
"good"--the uncoated paper must be removed by hand and exhibits very slight 
picking 
"pass"--the uncoated paper must be removed by hand and exhibits significant 
picking, but no fiber tear 
"blocked"--the uncoated paper must be removed by hand and exhibits fiber 
tear 
3. Humidity Resistance is tested in the same manner as blocking resistance 
with the exception that the test is conducted at 38.degree. C. and 90% 
relative humidity for 24 hours. 
4. Rate of Remoistening & Bondability First a hot melt adhesive sample and 
metal draw down bar are heated in an oven at 165.degree. C. Once melted, a 
0.5 to 1.0 mil (0.001 cm to 0.003 cm) film is applied to a paper substrate 
that is taped onto the laboratory benchtop. After cooling, the adhesive 
thickness of each coated sheet of paper is measured to ensure the film 
thickness falls between 0.5 and 1.0 mils (0.001 cm and 0.003 cm) thickness 
and is then cut into 1/2 inch (1.3 cm) strips. Next, a 1/2 inch (1.3 cm) 
coated strip is moistened with an applicator containing room temperature 
water and immediately pressed onto a second piece of bond paper with 
medium finger pressure (as you would seal an envelope). Immediately the 
stop watch is started to measure the length of time elapsed from the point 
a coated strip is pressed onto bond paper until it is removed. When the 
coated strip is removed from the bond paper, the stop watch is stopped and 
the elapsed time and percent fiber tear is recorded. 
The rate of remoistening is determined to be the length of time it takes a 
hot melt adhesive to develop a fiber tearing bond. The percent fiber tear 
is also recorded. 
5. Rate of Set 
Molten adhesive ranging in temperature from about 160.degree. C. to about 
177.degree. C. is drawn down onto a paper substrate at a thickness of 0.5 
mil (0.001 cm). The film is evaluated by cautiously contacting the film 
with ones fingertips immediately after being drawn. A "fast setting" 
composition is tack-free in about one second or less, whereas a slow 
setting composition takes longer to become tack-free. 
TABLE 1 
__________________________________________________________________________ 
Ingredient Trade Name 
WT-% A B C D Example 1 Example 2 Example 3 Example 4 
__________________________________________________________________________ 
AQ-1045 87 82 44.5 42 27 57 
NP-2126 87 82 42.5 40 60 30 
Paricin 285 10 10 10 10 10 10 10 10 
Paricin 220 5 5 5 
Benzoflex 9-88 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 
Irganox 1010 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 
__________________________________________________________________________ 
PROPERTIES 
Rate of Remoistening & 
Bondability 
Initial - % Fiber Tear/Time 60/50 sec 80/45 sec 100/30 sec 100/30 sec 
100/30 sec 100/30 sec 
100/30 sec 100/30 sec 
After 24 hrs (% FT) 
transfer transfer 100 95 
10 95 10 100 
__________________________________________________________________________ 
Blocking Resistance 
At room temperature Good Good Blocked Good Good Good 
90% RH/38 C. Good Good Blocked Blocked Good Good Good Good 
Rate of Set Fast Fast Fast Fast Fast Fast Fast Fast 
Viscosity @ 163.degree. C. (cps) 755 572 2670 1255 1407 1005 
__________________________________________________________________________ 
Comparative Examples A and B comprises NP-2126, a polyamide commercially 
available from H.B. Fuller Company (St. Paul, Minn.) in combination with 
wax. Although this product has good blocking resistance, it tends to 
remoisten slowly. After a 50 second dwell time, only 60% fiber tear is 
achieved for Comparative Example A and 80% fiber tear after 45 seconds for 
Comparative Example B. In order to achieve 100% fiber tear, a dwell time 
of 120 seconds is required. Additionally, these products suffer by virtue 
of the fact that after 24 hours, adhesive transfer is evident rather than 
full-fiber tearing bonds. 
In contrast, Comparative Examples B and C comprise Eastman AQ-1045, a 0.21V 
water dispersible copolyester in combination with wax. Although this 
product has a fast rate of moistenability, i.e., forming a full-fiber 
tearing bond (100% FT) within 30 seconds, this product blocks at room 
temperature and at 90%RH/38.degree. C. 
Examples 1-4 represent thermoplastic compositions of the present invention. 
One would expect to achieve properties intermediate between the properties 
of a composition based solely on crystalline water sensitive polymer (A 
and B) and that of a composition based solely on amorphous water sensitive 
polymer (C and D). However, unexpectedly, the blocking tendencies of the 
copolyester are completely diminished without any compromise of the rate 
of bond formation. 
TABLE 2 
__________________________________________________________________________ 
Ingredient 
Trade name 
Wt-% E Example 5 Example 6 Example 7 Example 8 Example 9 
__________________________________________________________________________ 
Gohseran L-301 75 44.5 25 
Glycerine 12.5 
12 Hydroxy stearic acid 12.5 
NP-2126 42.5 65 40 40 40 
Paricin 285 10 
Benzoflex 9-88 2.5 10 
Irganox 1010 0.5 
R-219 60 
Eukaline 480 60 
HL-9449 60 
__________________________________________________________________________ 
PROPERTIES 
Rate of Remoistening & 
Bondability 
Initial - % Fiber Tear/Time 90/30 sec 75/30 sec 90/30 sec 90/30 sec 
After 24 hrs (% FT) 80/30 sec 
+0 90/30 sec 90%+ .about.40% 
__________________________________________________________________________ 
90%+ 
Blocking Resistance 
At room temperature Tacky Good Good Good Good Good 
90% RH/38 C. Blocked Good Good Good Good Good 
Rate of Set Fast Fast Fast Fast Fast Fast 
__________________________________________________________________________ 
Table 2 depicts an additional comparative example and further examples of 
the present invention employing other amorphous water sensitive polymers. 
Comparative Example E represents a water sensitive hot melt adhesive 
composition based on polyvinyl alcohol. Comparative Example E is slightly 
tacky at room temperature and blocks at conditions of 90% relative 
humidity and 38.degree. C. Examples 5 and 6 employ a crystalline water 
sensitive polyamide in combination with the amorphous polyvinyl alcohol, 
eliminating the poor blocking resistance. R-219 available from Moore 
Response (Green Bay, Wis.), Eukalin 480 available from Hunkeler 
Corporation (Marietta, Ga.) and HL-9449 available from H.B. Fuller Company 
represent commercially available remoistenable hot melt adhesives. The 
R-219 and Eukaline 480 are based on polyvinyl pyrrolidone/vinyl acetate, 
whereas the HL-9449 is based on polyethyloxazoline. All three of these 
products were found to block at conditions of 70% relative humidity and 
25.degree. C. However, upon blending these products with a crystalline 
water sensitive polymer the blocking resistance is significantly improved. 
TABLE 3 
__________________________________________________________________________ 
Ingredient 
Trade name 
Wt-% Example 10 Example 11 Example 12 Example 13 
__________________________________________________________________________ 
NP-2126 70 62.5 75 75 
AQ 35S 17 27 14.2 14.2 
Paricin 285 10 5 5 5 
Benzoflex 352 5 
Benzoflex 400 5 
Benzoflex 9-88 2.5 5 
Irganox 1010 0.5 0.5 0.5 0.5 
Cyanox LTDP 0.3 0.3 
__________________________________________________________________________ 
PROPERTIES 
Rate of Remoistening & 
Bondability 
Initial - % Fiber Tear/Time 100/30 sec. 100/30 sec. 100/30 sec. 100/30 
sec. 
After 24 hrs 100 F./90% RH 100% 100% 100% 100% 
__________________________________________________________________________ 
Blocking Resistance Good Good Good Good 
At 100 F./90% RH 
Rate of Set Fast Fast Fast Fast 
__________________________________________________________________________ 
Examples 10-13 exemplify thermoplastic compositions comprising an amorphous 
linear water dispersible copolyester and a crystalline water dispersible 
polyamide. These compositions also exhibit a fast rate of bond formation 
combined with good blocking resistance. 
The examples comprising water dispersible copolyester in combination with a 
crystalline water sensitive polymer are particularly well-suited for 
applications such as nonwoven construction and in-line film formation in 
view of the fast rate of set and that the composition is tap water 
soluble/dispersible, body fluid insoluble, and exhibits good blocking 
resistance.