U.S. patent application number 09/952801 was filed with the patent office on 2002-07-04 for antiblock coating for hot melt adhesives.
This patent application is currently assigned to Eastman Chemical Company. Invention is credited to Miller, Richard Anthony, Thompson, Rickey.
Application Number | 20020086154 09/952801 |
Document ID | / |
Family ID | 21937420 |
Filed Date | 2002-07-04 |
United States Patent
Application |
20020086154 |
Kind Code |
A1 |
Miller, Richard Anthony ; et
al. |
July 4, 2002 |
Antiblock coating for hot melt adhesives
Abstract
The present invention is directed to an antiblock coating
comprised of a composition that contains a dibenzoate ester moiety.
The dibenzoate ester compounds, particularly 1,4-CHDM dibenzoate,
provide an excellent non-stick coating to hot melt adhesives, thus
providing for easier packaging, storage, and processing. In
addition, such a coating facilitates recycling of materials to
which the hot melt adhesive is applied.
Inventors: |
Miller, Richard Anthony;
(Kingsport, TN) ; Thompson, Rickey; (Kingsport,
TN) |
Correspondence
Address: |
LaVonda R. DeWitt
NEEDLE & ROSENBERG, P.C.
The Candler Building, Suite 1200
127 Peachtree Street, N.E.
Atlanta
GA
30303-1811
US
|
Assignee: |
Eastman Chemical Company
|
Family ID: |
21937420 |
Appl. No.: |
09/952801 |
Filed: |
September 12, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09952801 |
Sep 12, 2001 |
|
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|
09071569 |
May 1, 1998 |
|
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60045356 |
May 2, 1997 |
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Current U.S.
Class: |
428/347 ;
428/349 |
Current CPC
Class: |
Y10T 428/2826 20150115;
C08L 67/025 20130101; Y10T 428/2891 20150115; Y10T 428/2878
20150115; Y10T 428/31786 20150401; Y10T 428/2852 20150115; Y10T
428/2813 20150115; C08J 3/124 20130101; C08J 2367/00 20130101; Y02P
20/582 20151101; Y10T 428/2817 20150115; C08L 67/025 20130101; C08L
67/00 20130101 |
Class at
Publication: |
428/347 ;
428/349 |
International
Class: |
B32B 007/12 |
Claims
We claim:
1. A coated substrate comprising a coating and a substrate, wherein
the coating comprises a dibenzoate ester compound.
2. The coated substrate according to claim 1, wherein the coating
has a glass transition temperature of above 23.degree. C.
3. The coated substrate according to claim 1, wherein the coating
has a glass transition temperature of above 60.degree. C.
4. The coated substrate according to claim 1, wherein the coating
has a ring ball softening point of from about 80 to about
140.degree. C.
5. The coated substrate according to claim 1, wherein the coating
is 1,4- or 1,3-cyclohexanedimethanol dibenzoate.
6. The coated substrate according to claim 1, wherein 0.5 grams or
greater of the coated substrate are soluble or dispersible in 100
ml. of water at room temperature and a neutral pH.
7. The coated substrate according to claim 1, wherein the substrate
is a hot melt adhesive composition.
8. The coated substrate according to claim 1, wherein the substrate
is a hot melt particulate adhesive composition.
9. The coated substrate according to claim 1, wherein the substrate
comprises a branched sulfopolyester.
10. The coated substrate according to claim 1, wherein the
substrate comprises one or more dibenzoate ester moieties.
11. The coated substrate according to claim 1, wherein the coating
is 1,4- or 1,3-cyclohexanedimethanol dibenzoate, and the substrate
is a hot melt particulate adhesive composition.
12. The coated substrate according to claim 1, wherein the coating
is 1,4- or 1,3-cyclohexanedimethanol dibenzoate, and the substrate
is a branched sulfopolyester.
13. The coated substrate according to claim 1, wherein the coating
is 1,4- or 1,3-cyclohexanedimethanol dibenzoate, and the substrate
comprises one or more dibenzoate ester moieties.
14. The coated substrate according to claim 1, wherein the coating
is 1,4- or 1,3-cyclohexanedimethanol dibenzoate, and the substrate
comprises from about 20 to about 80 weight parts of a linear water
dispersible polyester and from about 20 to about 80 weight parts of
a branched water dispersible polyester.
15. A process of coating a particulate adhesive composition
comprising contacting adhesive particles with a dibenzoate ester
compound.
16. The process according to claim 15, wherein the dibenzoate ester
is 1,4- or 1,3-cyclohexanedimethanol dibenzoate.
17. The process according to claim 15, wherein the adhesive
particles comprise one or more dibenzoate ester moieties.
18. The process according to claim 15, wherein the dibenzoate ester
is 1,4- or 1,3-cyclohexanedimethanol dibenzoate, and the adhesive
particles comprise a branched sulfopolyester.
19. A process of providing anti-block properties to a particulate
adhesive composition comprising contacting adhesive particles with
an antiblocking effective amount of a dibenzoate ester
compound.
20. The process according to claim 19, wherein the dibenzoate ester
is 1,4- or 1,3-cyclohexanedimethanol dibenzoate, and the adhesive
particles comprise a branched sulfopolyester.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. .sctn.
19(e) to United States Provisional Application Ser. No. 60/045,356,
filed May 2, 1997.
FIELD OF THE INVENTION
[0002] The present invention concerns a material that is useful for
coating substrates such as adhesives. More particularly, the
invention is directed to an antiblock coating for polymeric hot
melt adhesives, and is especially useful for preventing blocking of
hot melt adhesives when shipped in the form of particulates.
BACKGROUND OF THE INVENTION
[0003] Hot melt adhesives are useful for bonding together various
substrates such as wood, paper, plastics, textiles, and other
materials. Hot melt adhesives are prepared and shipped in many
configurations depending upon the end use for the adhesive. For
example, hot melt adhesives can be prepared and shipped in the
shape of films, rods, and particulates. Packaging and shipping
conditions for hot melt adhesives are important due to stability
and shelf life concerns with the polymers, and the potential for
blocking or agglomeration of the adhesive materials during shipping
or storage. It is especially important to prevent blocking of
particulate hot melt adhesives during shipping, because the
particles must flow freely in order to be incorporated into a
mixing vessel for final hot melt compounding. Hot melt adhesives
that are particularly prone to blocking include the water
dispersible polyesters described in U.S. Pat. Nos. 5,543,488,
5,552,495, 5,571,876, and 5,605,764.
[0004] In light of the above it would be very desirable to produce
a hot melt adhesive with a non-tacky coating that maintains the
desirable properties of presently available hot melt adhesives.
SUMMARY OF THE INVENTION
[0005] The applicants have unexpectedly discovered that dibenzoate
esters, and compounds that contain dibenzoate ester moieties
(hereinafter "dibenzoate ester compounds"), provide an improved
antiblock coating that prevents adhesive materials from blocking to
other adhesive materials. Thus, in one aspect the invention
provides a coated substrate comprising a coating and a substrate,
wherein the coating comprises a dibenzoate ester compound. In
another aspect the invention provides a process of coating an
adhesive material comprising contacting the adhesive material with
a dibenzoate ester compound. In still another aspect the invention
provides a process of providing anti-block properties to a
particulate adhesive composition comprising contacting adhesive
particles with an antiblocking effective amount of a dibenzoate
ester compound. The coated substrate has excellent hot melt
adhesive properties. In a preferred embodiment, wherein the
dibenzoate ester coats a water-dispersible adhesive material, the
antiblock coating is also water-dispersible, thereby providing a
coated substrate that is totally recyclable. The composition can be
completely repulpable and readily removed from the wood or paper
fibers used in disposable products.
[0006] Additional advantages of the invention will be set forth in
part in the following discussion, and in part will be obvious from
the discussion, or may be learned by practice of the invention. The
advantages of the invention will be realized and attained by means
of the elements and combinations particularly pointed out in the
appended claims. It is to be understood that both the foregoing
general description and the following detailed discussion are
exemplary and explanatory only and are not restrictive of the
invention, as claimed.
DISCUSSION
[0007] The present invention may be understood more readily by
reference to the following detailed description of embodiments of
the invention and the Examples included therein. However, before
the present compounds, compositions and methods are disclosed and
described, it is to be understood that this invention is not
limited to specific synthetic methods, or to specific materials or
formulations, as such may, of course, vary. It is also to be
understood that the terminology used herein is for the purpose of
describing particular embodiments only and is not intended to be
limiting.
[0008] Furthermore, it must be noted that, as used in the
specification and the appended claims, the singular forms "a," "an"
and "the" include plural referents unless the context clearly
dictates otherwise. Thus, for example, reference to "an aromatic
compound" includes mixtures of aromatic compounds.
[0009] Ranges are often expressed herein as from "about" one
particular value, and/or to "about" another particular value. When
such a range is expressed, another embodiment includes from the one
particular value and/or to the other particular value. Similarly,
when values are expressed as approximations, by use of the
antecedent "about," the particular value forms another
embodiment.
[0010] In this specification and in the claims which follow,
reference will be made to a number of terms which shall be defined
to have the following meanings:
[0011] Parts by weight, of a particular element or component in a
composition or article, denotes the weight relationship between the
element or component and any other elements or components in the
composition or article for which a part by weight is expressed.
Thus, in a compound containing 2 parts by weight of component X and
5 parts by weight component Y, X and Y are present at a weight
ratio of 2:5, and are present in such ratio regardless of whether
additional components are contained in the compound.
[0012] A residue of a chemical species, as used in the
specification and concluding claims, refers to the moiety that is
the resulting product of the chemical species in a particular
reaction scheme or subsequent formulation or chemical product,
regardless of whether the moiety is actually obtained from the
chemical species. Thus, an ethylene glycol residue in a polyester
refers to one or more --OCH.sub.2CH.sub.2O-- units in the
polyester, regardless of whether ethylene glycol was used to
prepare the polyester. Similarly, a sebacic acid residue in a
polyester refers to one or more --CO(CH.sub.2).sub.8CO-- moieties
in the polyester, regardless of whether the residue is obtained by
reacting sebacic acid or an ester thereof to obtain the
polyester.
[0013] "Optional" or "optionally" means that the subsequently
described event or circumstance may or may not occur, and that the
description includes instances where said event or circumstance
occurs and instances where it does not. For example, the phrase
"optionally substituted lower alkyl" means that the lower alkyl
group may or may not be substituted and that the description
includes both unsubstituted lower alkyl and lower alkyl where there
is substitution.
[0014] By the term "effective amount" of a compound or property as
provided herein is meant such amount as is capable of performing
the function of the compound or property for which an effective
amount is expressed. As will be pointed out below, the exact amount
required will vary from process to process, depending on recognized
variables such as the compounds employed and the processing
conditions observed. Thus, it is not possible to specify an exact
"effective amount." However, an appropriate effective amount may be
determined by one of ordinary skill in the art using only routine
experimentation.
[0015] The term "modified" is often used herein to describe
polymers and means that a particular monomeric unit that would
typically make up the pure polymer has been replaced by another
monomeric unit that shares a common polymerization capacity with
the replaced monomeric unit. Thus, for example, it is possible to
substitute diol residues for glycol in poly(ethylene glycol), in
which case the poly(ethylene glycol) will be "modified" with the
diol. If the poly(ethylene glycol) is modified with a mole
percentage of the diol, then such a mole percentage is based upon
the total number of moles of glycol that would be present in the
pure polymer but for the modification. Thus, in a poly(ethylene
glycol) that has been modified by 50 mole % with a diol, the diol
and glycol residues are present in equimolar amounts.
[0016] The term "polyester" includes copolyesters.
[0017] The term "dibenzoate ester compound" includes compounds that
contain one or more dibenzoate ester moieties.
[0018] In one aspect the invention provides a coated substrate
comprising a coating and a substrate, wherein the coating comprises
a dibenzoate ester compound. In another aspect the invention
provides a process of coating an adhesive material comprising
contacting the adhesive material with a dibenzoate ester compound.
In still another aspect the invention provides a process of
providing anti-block properties to a particulate adhesive
composition comprising contacting adhesive particles with an
antiblocking effective amount of a dibenzoate ester compound.
[0019] Preferred dibenzoate ester compounds are solid at room
temperature, and preferably have a glass transition temperature of
greater than 23.degree. C., more preferably have a glass transition
temperature of greater than 45.degree. C., even more preferably
have a glass transition temperature above 60.degree. C., and still
even more preferably have a glass transition temperature above
80.degree. C. In any event the glass transition temperature
preferably does not exceed 200.degree. C., and even more preferably
does not exceed 120.degree. C. In another embodiment the dibenzoate
ester compound has a ring ball softening point (as measured by ASTM
E-28) of from about 80 to about 140.degree. C., and more preferably
from about 105 to about 120.degree. C.
[0020] In many embodiments the coated substrate of this invention
is substantially dispersible or soluble in water, and thus
facilitates recycling of materials to which the coated substrate my
be applied. In a preferred embodiment 0.5 grams or greater
(preferably 1.0 grams or greater) of the coated substrate are
dispersible or soluble in 100 ml. of water that has a neutral pH at
room temperature. In certain embodiments, however, the quantities
that are preferably and more preferably dissolved are completely
soluble or dispersible in 100 ml. of water only at temperatures
above 40.degree. C., or only at temperatures above 60.degree. C.,
or only under alkaline conditions.
[0021] A surprising aspect of many embodiments of the present
invention is the interaction between the dibenzoate ester compound
and substrates of this invention, and the resulting solubility or
dispersibility of the coated substrate. In many embodiments, for
example, the dibenzoate ester compound, by itself, is essentially
insoluble or nondispersible under conditions at which the coated
substrate is substantially soluble or dispersible. These surprising
results are often obtained when the substrate and coating each
comprise the same dibenzoate ester moiety.
[0022] A particularly preferred dibenzoate ester compound is 1,3-
or 1,4-cyclohexanedimethanol dibenzoate, and even more preferably
1,4-cyclohexanedimethanol dibenzoate. An example of such a product
is Benzoflex 352 from Velsicol Chemical Corporation. However, other
dibenzoate ester compounds could be used in the practice of the
present invention.
[0023] Another preferred dibenzoate ester compound is selected from
the class of linear polyesters that contain residues of 1,3- or
1,4- cyclohexanedimethanol (preferably 1,4-) and terephthalic or
isophthalic acid (preferably isophthalic). A particularly preferred
polyester contains diacid monomer residues that are about 75 to 90
mol percent isophthalic acid residues, and about 10 to 25 mol
percent 5-sodiosulfoisophthalic acid monomer residues; and diol
monomer residues of greater than about 45 mol percent diethylene
glycol monomer residues and less than 55 mol percent
1,4-cyclohexanedimethanol residues.
[0024] The dibenzoate ester compound is coated onto the substrate,
preferably at low addition levels, by methods known in the art,
such as dip coating, high-speed coaters, or spray coating. In a
preferred embodiment, a molten dibenzoate ester compound is brought
to a temperature of 177.degree. C. and small particles of the
substrate are dip coated in the molten plasticizer. The particles
are preferably coated with about 0.5 to about 5.0 weight percent of
the dibenzoate ester compound, and more preferably from about 0.9
to about 1.3 weight percent, based on the weight of the coated
particle.
[0025] In one embodiment the substrate is a hot melt adhesive
composition that preferably is water dispersible. The substrate is
typically a polyester, polyamide, or polyesteramide, and preferably
has a glass transition temperature from about 0 to about 90.degree.
C. Branched sulfopolyesters, and particularly the branched
sulfopolyesters of (II) below, are especially preferred
compositions for the substrate of this invention.
[0026] In another embodiment the substrate is a blend of two
polyesters, each of which may be linear or branched, although
preferably the blend is a mixture of linear and branched
polyesters. In another preferred embodiment, the coated composition
contains about 20 to 80 weight percent of linear water-dispersible
polyester of (I) and about 20 to 80 weight percent of branched
water-dispersible polyester of (II), where (I) and (II) are as set
forth below.
[0027] The linear water-dispersible polyester of (I) is made of the
residues or moieties of the following reaction products:
[0028] (i) at least one difunctional dicarboxylic acid which is not
a sulfomonomer;
[0029] (ii) about 4 to 25 mol percent, based on the total of all
acid, hydroxyl and amino equivalence, of residues of at least one
difunctional sulfomonomer containing at least one sulfonate group
bonded to an aromatic ring wherein the functional groups are
hydroxyl, carboxyl, or amino;
[0030] (iii) at least one diol or a mixture of a diol and a diamine
comprising:
[0031] (a) at least 15 mol percent, based on the total mol percent
of diol moieties or diol and diamine moieties, of a diol or diamine
having the formula H(--OCH.sub.2CH.sub.2--).sub.nOH and
HRN--(O--CH.sub.2CH.sub.2--O- ).sub.n--NHR, wherein n is 2 to about
20 and R is hydrogen or C.sub.1-C.sub.6 alkyl, or
[0032] (b) about 0.1 to less than about 15 mol percent, based on
the total mol percent of diol moieties or diol and diamine
moieties, of moieties of a poly(ethylene glycol) having the formula
H(--OCH.sub.2CH.sub.2--).sub.n- OH wherein n is 2 to about 500;
[0033] (iv) optionally, moieties of at least one difunctional
monomer reactant selected from hydroxycarboxylic acids,
aminocarboxylic acids and aminoalkanols; wherein the polymer
contains substantially equal mol proportions of acid equivalents
(100 mol %) and diol or diol and diamine equivalents (100 mol %)
wherein at least 20 weight percent of the groups linking the
moieties of the monomeric units are ester linkages and wherein the
inherent viscosity is at least 0.1 dL/g measured in a 60/40 parts
by weight solution of phenol/tetrachloroethane at 25.degree. C. and
at a concentration of about 0.25 g of polymer in 100 ml of the
solvent. This linear water-dispersible polyester composition of (I)
is described in detail in U.S. Pat. No. 3,734,874; 3,779,993;
4,233,196; and 4,335,220, the disclosures of which are incorporated
herein by reference in their entirety.
[0034] The sulfonate-containing, water-dispersible, linear
polyesters of (I) comprise polyesters, including polyesteramides,
having repeating, alternating residues or moieties of one or more
dicarboxylic acids which is not a sulfomonomer and one or more
diols or a combination of one or more diols and one or more
diamines wherein the mol percentages are based on 100 mol percent
dicarboxylic acid residues and 100 mol percent diol or diol and
diamine residues, for a total of 200 mol percent. Alternatively,
the polyesters can include residues of monomers having mixed
functionality such as hydroxycarboxylic acids, aminocarboxylic
acids and/or aminoalkanols.
[0035] The water-dispersible polyesters of (I) have an inherent
viscosity of at least 0.1 dL/g, preferably about 0.28 to 0.45 dL/g,
measured in a 60/40 parts by weight solution of
phenol/tetrachloroethane at 25.degree. C. and at a concentration of
about 0.25 g of polymer in 100 ml of solvent. Examples of suitable
difunctional dicarboxylic acid monomers used to make the residue of
(i) include aliphatic dicarboxylic acids, alicyclic dicarboxylic
acids, aromatic dicarboxylic acids, or mixtures of two or more of
these acids. Examples of preferred suitable dicarboxylic acids
include succinic; glutaric; adipic; azelaic; sebacic; fumaric;
maleic; itaconic; 1,4-cyclohexanedicarboxylic; phthalic;
terephthalic; and isophthalic. If terephthalic acid is used as the
dicarboxylic acid component of the polyester, superior results are
achieved when at least 5 mol percent of one of the other acids is
also used. It should be understood that the use of the
corresponding acid anhydrides, esters, and acid chlorides of these
acids is included in the term "dicarboxylic acid".
[0036] The difunctional sulfo-monomer component of (ii) is
preferably a dicarboxylic acid or ester thereof containing a metal
sulfonate group or a glycol containing a metal sulfonate group or a
hydroxy acid containing metal sulfonate group. The cation of the
sulfonate salt can be NH.sub.4.sup.+, or the metal ions Li.sup.+,
Na.sup.+, K.sup.+, Mg.sup.++, Ca.sup.++, Cu.sup.++, Ni.sup.++,
Fe.sup.++, Fe.sup.+++, and the like. Residue or reactant (ii) in
the polyester of the present invention is a difunctional monomer
containing a --SO.sub.3M group attached to an aromatic nucleus,
wherein M is hydrogen, NH.sub.4.sup.+, or a metal ion. The
difunctional monomer component may be either a dicarboxylic acid or
a diol adduct containing an --SO.sub.3M group. The cation of the
sulfonate salt group can be NH.sub.4.sup.+, or the metal ions
Li.sup.+, Na.sup.+, K.sup.+, Mg.sup.++, Ca.sup.++, Cu.sup.++,
Ni.sup.++, Fe.sup.++, Fe.sup.+++, and the like. Preferred are
monovalent cations, such as NH.sub.4.sup.+ and the monovalent
cations of lithium, sodium, and potassium, when stability in water
is desired.
[0037] The --SO.sub.3M group is attached to an aromatic nucleus,
examples of which include benzene, naphthalene, anthracene,
diphenyl, oxydiphenyl, sulfonyldiphenyl, and methylenediphenyl. The
nonmetallic portion of the nonmetallic sulfonate group optionally
present in reactant (ii) is a nitrogen-based cation derived from
nitrogen-containing bases which may be aliphatic, cycloaliphatic or
aromatic basic compounds that have ionization constants in water at
25 C of 10.sup.-3 to 10.sup.-10, and more preferably 10.sup.-5 to
10.sup.-8. Especially preferred nitrogen-containing bases are
ammonia, dimethylethanolamine, diethanolamine, triethanolamine,
pyridine, morpholine, and piperidine. Such nitrogen-containing
bases and cations derived therefrom are described in U.S. Pat. No.
4,304,901, the disclosure of which is incorporated herein by
reference in its entirety. It is preferred that reactant (ii) is
present in an amount of 4 to 25 mol percent, more preferably about
8 to 18 mol percent, with a mol percent of about 10 being most
preferred.
[0038] Examples of suitable poly(ethylene glycols) of (iii) include
relatively high molecular weight polyethylene glycols, some of
which are available commercially under the designation "Carbowax",
a product of Union Carbide. Poly(ethylene glycols) having molecular
weights of from about 500 to about 5000 are especially
suitable.
[0039] The remaining portion of the glycol component may consist of
aliphatic, alicyclic, and aralkyl glycols. Examples of these
glycols include ethylene glycol; propylene glycol; 1,3-propanediol;
2,4-dimethyl-2-ethylhexane-1,3-diol; 2,2-dimethyl-1,3-propanediol;
2-ethyl-2-butyl-1,3-propanediol;
2-ethyl-2-isobutyl-1,3-propanediol; 1,3-butanediol; 1,4-butanediol;
1,5-pentanediol; 1,6-hexanediol; 2,2,4-trimethyl-1,6-hexanediol;
thiodiethanol; 1,2-cyclohexanedimethanol;
1,3-cyclohexanedimethanol; 1,4-cyclohexanedimethanol;
2,2,4,4-tetramethyl-1,3-cyclobutanediol; p-xylylenediol. Copolymers
may be prepared from two or more of the above glycols.
[0040] Advantageous examples of difunctional monomer component of
(iii) which are diamines include ethylenediamine;
hexamethylenediamine; 2,2,4-trimethylhexa-methylenediamine;
4-oxaheptane-1 ,4-diamine, 4,7-dioxadecane-1,10-diamine;
1,4-cyclohexanebismethylamine; 1,3-cyclohexanebismethylamine;
heptamethylenediamine; dodecamethylenediamine, etc.
[0041] Advantageous difunctional components which are aminoalcohols
or aminoalkanols include aromatic, aliphatic, heterocyclic, and
other types in regard to component (iv). Specific examples include
5-aminopentanol-1,4-aminomethylcyclohexanemethanol,
5-amino-2-ethyl-pentanol-1,2-(4-.beta.-hydroxyethoxyphenyl)-1-aminoethane-
, 3-amino-2,2-dimethylpropanol, hydroxyethylamine, etc. Generally
these aminoalcohols contain from 2 to 20 carbon atoms, one -NRH
group and one --CR.sub.2--OH group.
[0042] Advantageous difunctional monomer components which are
aminocarboxylic acids include aromatic, aliphatic, heterocyclic,
and other types in regard to component (iv) and include lactams.
Specific examples include 6-aminocaproic acid, its lactam known as
caprolactam, omega aminoundecanoic acid,
3-amino-2-dimethylpropionic acid, 4-(.beta.-aminoethyl)benzoic
acid, 2-(.beta.-aminopropoxy)benzoic acid,
4-aminomethylcyclohexanecarboxylic acid,
2-(.beta.-aminopropoxy)cyclohexa- necarboxylic acid, etc.
Generally, these compounds contain from 2 to 20 carbon atoms.
[0043] Preferred water-dispersible linear polyesters of (I) contain
diacid monomer residues that are about 75 to 90 mol percent
isophthalic acid residues, and about 10 to 25 mol percent
5-sodiosulfoisophthalic acid monomer residues; and diol monomer
residues of about 45 to 100 mol percent diethylene glycol monomer
residues and 0 up to 55 mol percent 1,4-cyclohexanedimethanol. The
more preferred water-dispersible linear polyesters of (I) have a
weight average molecular weight in the range of about 4,000 to
6,000 by gas-phase chromatography based on a polystyrene standard,
and a Tg range of about 25 to 88.degree. C., preferably about 29 to
55.degree. C.
[0044] In a preferred embodiment, the branched water-dispersible
polyester of (II) is made of the moieties of the reaction
products:
[0045] (a) at least one difunctional dicarboxylic acid which is not
a sulfomonomer;
[0046] (b) about one to 20 mol percent, based on the total of acid,
hydroxyl and amino equivalents, of residues of at least one
difunctional sulfomonomer containing at least one sulfonate group
bonded to an aromatic ring wherein the functional groups are
hydroxyl, carboxyl, or amino;
[0047] (c) at least one difunctional reactant selected from a
glycol or a mixture of glycol and diamine having two -NRH groups,
the glycol containing two --C(R.sup.1).sub.2--OH groups wherein
each R.sup.1 in the reactant may be the same or different and is
independently selected from hydrogen or an alkyl group of 1 to 6
carbon atoms;
[0048] (d) about 0 to 40 mol % of a difunctional reactant selected
from hydroxycarboxylic acids having one --C(R--).sub.2--OH group,
aminocarboxylic acids having one -HRH group, amino-alcohols having
one --C(R--).sub.2--OH group and one --NRH group, or mixtures of
said difunctional reactants wherein R in the reactant may be the
same or different and is independently selected from hydrogen or an
alkyl group of 1 to 6 carbon atoms; and
[0049] (e) 1 to 40 mol % of a "multifunctional" or
"branch-inducing" reactant containing at least three functional
groups selected from hydroxyl, carboxyl, amino, and mixtures
thereof;
[0050] wherein the polyester has a predispersion pH greater than 4
and all stated mol percents are based on the total of all acid,
hydroxyl, and amino group containing reactants being equal to 200
mol percent, and wherein the polymer containing a portion of the
acid-group containing reactants (100 mol percent acid) to hydroxyl
and amino-group containing reactants (100 mol %) such that the
value of EQ (base) divided by EQ (acid) is between 1 and 1.6.
[0051] The branched water-dispersible polyesters of (II) are
disclosed in detail in U.S. Pat. No. 5,218,042, the disclosure of
which is incorporated herein by reference in its entirety. U.S.
Pat. No. 5,218,042 is directed towards increasing the stability of
dispersions in water and thus endcaps the acid groups or forms a
diol adduct of a dicarboxylic sulfomonomer to maintain dispersion
stability. However, the present invention is not necessarily
directed towards maintaining a stable emulsion, but can be directed
simply at producing an emulsion by pulping and dissolving the
hot-melt adhesive in water until it is separated from the fibers.
Therefore, endcapping and forming a diol adduct of the sulfomonomer
is simply an alternative and not a requirement for the present
invention.
[0052] The polyester of (II) is branched by virtue of the presence
of a multifunctional reactant that contains at least three
functional groups selected from hydroxyl, carboxyl, and amino. The
difunctional dicarboxylic acid which is not a sulfomonomer of (a)
can be the same or different as that in (i) and is generally
selected from the same dicarboxylic acids as in (i) from the
polyester of (I) above. The difunctional sulfomonomer of (b) can
also be the same as the difunctional sulfomonomer used in (i) in
the polyester of (I) above or selected from suitable difunctional
sulfomonomers disclosed above.
[0053] It is preferred that reactant (c) is a glycol or mixture of
glycols. The glycol component may consist of aliphatic, alicyclic,
and aralkyl glycols. Examples of these glycols include ethylene
glycol; propylene glycol; 1,3-propanediol;
2,4-dimethyl-2-ethyl-hexane-1,3-diol; 2,2-dimethyl-1,3-propanediol;
2-ethyl-2-butyl-1,3-propanediol;
2-ethyl-2-isobutyl-1,3-propanediol; 1,3-butanediol; 1,4-butanediol;
1,5-pentanediol; 1,6-hexanediol; 2,2,4-trimethyl-1,6-hexanediol;
thiodiethanol; 1,2-cyclohexanedimethanol;
1,3-cyclohexanedimethanol; 1,4-cyclohexanedimethanol;
2,2,4,4-tetramethyl-1,3-cyclobutanediol; p-xylylenediol. Examples
of other suitable glycols are poly(ethylene glycols) which include
diethylene glycol, triethylene glycol, tetraethylene glycol, and
pentaethylene, hexaethylene, heptaethylene, octaethylene,
nonaethylene, and decaethylene glycols, and mixtures thereof. A
preferred poly(ethylene glycol) employed in the polyester of the
present invention is diethylene glycol or triethylene glycol or
mixtures thereof. Copolymers may be prepared from two or more of
the above glycols. Preferred glycols include ethylene glycol;
diethylene glycol; 2,2-dimethyl-1,3-propanediol;
2-ethyl-2-butyl-1,3-propanediol; 2,2,4-trimethyl-1,3-pentanediol;
1,4-cyclohexane-dimethanol; 1,3-cyclo-hexanedimethanol;
hydroxypivalyl hydroxypivalate; dipropylene glycol; 1,6-hexanediol;
1,10-decanediol; 1,3-butanediol; hydrogenated bisphenol A;
1,4-butanediol; and the like.
[0054] Advantageous difunctional components which are aminoalcohols
include aromatic, aliphatic, heterocyclic and other types as in
regard to component (d). Specific examples include
5-aminopentanol-1,4-aminomethylc- yclohexanemethanol,
5-amino-2-ethyl-pentanol-1,2-(4-.beta.-hydroxyethoxyph-
enyl)-1-aminoethane, 3-amino-2,2-dimethylpropanol,
hydroxyethylamine, etc. Generally these aminoalcohols contain from
2 to 20 carbon atoms, one --NRH group and one --C(R).sub.2--OH
group.
[0055] Advantageous difunctional monomer components which are
aminocarboxylic acids include aromatic aliphatic, heterocyclic, and
other types as in regard to component (d) and include lactams.
Specific examples include 6-aminocaproic acid, its lactam known as
caprolactam, omega-aminoundecanoic acid,
3-amino-2-dimethylpropionic acid, 4-(.beta.-aminoethyl)-benzoic
acid, 2-(.beta.-aminopropoxy)benzoic acid,
4-aminomethylcyclohexanecarboxylic acid,
2-(B-aminopropoxy)cyclohexanecar- boxylic acid, etc. Generally
these compounds contain from 2 to 20 carbon atoms.
[0056] Advantageous examples of difunctional monomer component (d)
which are diamines include ethylenediamine; hexamethylenediamine;
2,2,4-trimethylhexamethylenediamine; 4-oxaheptane-1,4-diamine;
4,7-dioxadecane-1,10-diamine; 1,4-cyclohexanebismethylamine;
1,3-cycloheptamethylenediamine; dodecamethylenediamine, etc.
[0057] Examples of preferred multifunctional reactants of (e) are
trimethylpropane (TMP), trimethylolethane (TME), glycerine,
pentaerythritol, erythritol, threitol, dipentaerythritol, sorbitol,
trimellitic anhydride, pyromellitic dianhydride, and
dimethylolpropionic acid with TMP being most preferred. In a
preferred branched water-dispersible polyester of (II), the
dicarboxylic acid of (a) is selected from isophthalic acid or
adipic acid and mixtures thereof, the dicarboxylic acid
sulfomonomer of (b) is 5-sodiosulfoisophthalic acid, the glycol
component in (c) is neopentyl glycol, no (d) component is present,
and the multifunctional reactant of (e) is TMP. It is further
preferred that the mol percent of the sulfomonomer such as
sodiosulfoisophthalic acid of (b) be present in a concentration of
about 3 to 6 mol percent, more preferably about 3 to 4 mol percent
based on the total mols of difunctional dicarboxylic acid monomers
present. Preferred amounts of (e) are about 3 to 15 mol percent
with about 7 to 8 mol percent (e) being most preferred.
[0058] To prepare water-dispersible hot melt adhesives of the
present invention that contain both (I) and (II), the
water-dispersible linear polyester composition of (I) can be
blended with the branched water-dispersible polyester composition
of (II) at temperatures greater than 200.degree. C., preferably
about 225.degree. C., for at least two hours. The relative amounts
of the two polyesters vary from about 20 to 80 weight percent of
the polyester of (I) and about 20 to 80 weight percent of the
polyester of (II). The concentration of these two polyesters in the
hot melt adhesive composition according to this embodiment is
preferably greater than 30 but less than 80 weight percent
polyester of (I) and greater than 20 but less than 70 weight
percent of the polyester of (II). The concentration of the two
polyesters is more preferably about 40 to 77 weight percent (I) and
about 23 to 60 weight percent of (II), even more preferably about
60 to 75 weight percent of (I) and about 25 to 40 weight percent of
(II) with a concentration of the two polyesters in weight percent
of about 70 (I) and about 30 (II) being most preferred.
[0059] Higher amounts of the polyester of (I) increase the melting
point of the final adhesive composition. At amounts of the
polyester of (I) higher that 80 weight percent, the adhesive has
too high of a melting point to be practical. Higher amounts of the
polyester of (II) decrease the melting point of the final adhesive.
At amounts of the polyester of (II) higher that 80 weight percent,
sometimes higher than 70, the adhesive has too low of a melting
point to be practical.
[0060] The final hot melt adhesive composition substrates
preferably have a weight average molecular weight of about 2,000 to
10,000, more preferably about 5,000 to 5,500 as determined by gas
phase chromatography based on a polystyrene standard. The preferred
Tg of the final adhesive composition according to the present
invention varies from about 4 to 22.degree. C., preferably about 4
to 8.degree. C. The final hot melt adhesive composition according
to the present invention preferably has a viscosity of about 1,500
to about 30,000 centipoise at 350.degree. F. (175.degree. C.), more
preferably about 5,000 to 20,000 cP at 350.degree. F. (175.degree.
C.).
[0061] The hot melt adhesive compositions according to the present
invention are particularly useful due to their good combination of
properties and are especially suitable for use as adhesives for
paper products and wood pulp because in many embodiments they are
easily recyclable and repulpable. The hot melt adhesives according
to the present invention are recyclable/repulpable and improved
over prior art repulpable hot melt adhesive compositions in that
the set time, temperature sensitivity, compatibility, stability on
storage, shear strength, tensile strength, viscosity, and cold flow
resistance are improved.
[0062] The hot melt adhesives according to the present invention
can also be used for adhesively bonding non-woven assemblies, such
as adhesively bonding nonwoven materials to polyethylene or other
polyolefin films. Indeed, the hot melt adhesives preferably can be
applied to many materials, including polyamides, polyimides, and
polyolefins. Most preferably such materials have an inherent
viscosity from about 0.2 to about 1.0 and, in a separate
embodiment, a melt temperature above about 60.degree. C. In
particular embodiments, the coated substrates of this invention are
used as adhesives in feminine hygiene products, in diapers, and in
cigarette filters.
[0063] The hot melt adhesive composition according to the present
invention can also contain standard additives including
stabilizers, preferably about 0.1 to about 0.5 weight percent
stabilizers. Suitable stabilizers include the antioxidant type and
generally consist of stericly hindered phenols, or sulfur or
phosphorous substituted phenols. An especially useful antioxidant
is Irganox 1010 (from Ciba-Geigy, Hawthorne, N.Y.) which is a
pentaerythritol tetrakis-3(3,5-di-tertiarybut-
yl-4-hydroxyphenyl)propionate. Other additives such as plasticizers
(e.g., phenols and phthalate esters), UV light absorbers,
colorants, tackifiers and fillers can be present in small amounts
as needed and as known in the adhesive art.
Experimental
[0064] The following examples are put forth so as to provide those
of ordinary skill in the art with a complete disclosure and
description of how the compounds claimed herein are made and
evaluated, and are intended to be purely exemplary of the invention
and are not intended to limit the scope of what the inventors
regard as their invention. Efforts have been made to ensure
accuracy with respect to numbers (e.g., amounts, temperature, etc.)
but some errors and deviations should be accounted for. Unless
indicated otherwise, parts are parts by weight, temperature is in
.degree. C. or is at room temperature, and pressure is at or near
atmospheric.
[0065] In the following examples GEL Permeation Chromatography
(GPC) is used for determination of the molecular weight
distribution averages: Mw, Mn, Mw/Mn (polydispersity), and Mz.
Approximately 60 milligrams of sample is weighed and dissolved in
20 ml. of tetrahydrofuran (THF) containing toluene (internal std.)
at a level of 0.3% (v/v). The sample is filtered (if necessary) and
then run on the GPC system. The data system generates a report
showing: (1.times.) the molecular weight distribution averages,
(2.times.) a time slice report, and (3.times.) standard, purchased
from Polymer Laboratories, covering a molecular weight range of 580
to 1,030,000. The mode of calibration is "Narrow MW Standard Peak
Positions".
EXAMPLE 1
Preparation of Linear Water-Dispersible Polyester Composition I
[0066] A 500-mL, round bottom flask equipped with a ground-glass
head, an agitator shaft, nitrogen inlet, and a sidearm was charged
with 73.87 g (0.445 mol) of isophthalic acid, 14.74 g (0.055 mol)
of 5-sodiosulfoisophthalic acid, 81 g (0.75 mol) of diethylene
glycol, 0.19 grams of titanium tetraisopropoxide and 0.847 g
(0.0055 mol) of sodium acetate tetrahydrate. The flask was immersed
in a Belmont bath at 200.degree. C. for two hours under a nitrogen
sweep. Heating was stopped and the copolyester was removed from the
flask. The polymer had an inherent viscosity of 0.45 dL/g according
to ASTM D3835-79 and a glass transition temperature of 29.degree.
C. as measured by differential scanning colorimetry (DSC) analysis.
The polymer, which was transparent and amorphous, was extruded and
pelletized. The polymer had a weight average molecular weight (Mw)
of 8,924 and a number average molecular weight (Mn) of 5,422 by GPC
using a polystyrene standard.
EXAMPLE 2
Preparation of Branched Water-dispersible Polyester Composition
II
[0067] To a three-neck round-bottom flask equipped with a
mechanical stirrer, a stream partial condenser a Dean-Stark trap,
and a water condenser were charged the following reactants:
neopentyl glycol (363.38 g, 3.49 m), 5-sodiosulfoisophthalic acid
(29.30 g, 0.109 m) and the catalyst, Fascat 4100 (Atochem North
America, Inc.) (0.56 g). The mixture was heated to 150.degree. C.
and stirred under N.sub.2 atmosphere and the temperature then
gradually increased to 220.degree. C. and the distillate (water)
was collected in the Dean-Stark trap until the mixture was clear
(about 1 hr). The acid number was determined to be close to zero,
and the mixture was cooled to 150.degree. C. The second stage
reactants, trimethylolpropane (75.4 g, 0.563 m), isophthalic acid
(329.01 g, 1.98 m) and adipic acid (202.25 g, 1.38 m) were then
added. The temperature was gradually raised to 220.degree. C. and
the reaction continued for four more hours to yield a resin with an
acid number of 3.6. The polymer had a weight average molecular
weight (Mw) of 6,241, a number average
[0068] molecular weight (Mn) of 1,740 and a polydispersity index of
3.6, determined by GPC using a polystyrene standard.
EXAMPLE 3
Preparation of a Water-Dispersible Hot-melt Adhesive
[0069] A blend of the linear water-dispersible polyester polymer I
prepared as in Example 1 (70 parts) by weight and the branched
water-dispersible polyester polymer II of Example 2 (30 parts) by
weight was prepared by combining the two polymers and stirring at
about 225.degree. C. for 2 hours to produce the adhesive
composition. The composition had a Tg of about 11.degree. C., a
weight average molecular weight of 5,410, a number average
molecular weight of 1,554, and a viscosity of 19,450 centipoise at
350.degree. F. (175.degree. C.) as determined on a Brookfield HV:
II Viscometer. The adhesive had a fast set time, as determined by a
standard procedure (TAPPI Symposium, Recyclable/Repulpable Hot
Melts--A Summary--U.S.A. and Europe, June, 1990, by Michael J.
Ambrosini) on a corrugated kraftboard substrate, good lap sheer
strength (ASTM D1002 Test Method) and good tensile strength (ASTM
412 Test Method). Into 100 ml of hot water (65-80.degree. C.) at a
pH of 7.8, were mixed 0.5 grams of adhesive chips. Within 15
minutes under mild agitation the adhesive was completely dispersed
in the water, forming a milky mixture.
EXAMPLE 4
[0070] An adhesive composition was prepared by blending 60 parts by
weight of the linear water-dispersible polymer prepared as in
Example 1 with 40 parts by weight of the branched water-dispersible
polyester of Example 2 and the properties of the polymer and the
polymer and adhesive properties determined as in Example 3 above.
The adhesive chips were dispersed in hot water as in Example 3
within 15 minutes. The adhesive had good repulping properties, a Tg
of about 8.4.degree. C., a weight average molecular weight of
5,272, a number average molecular weight of 1,563 and a viscosity
of 17,400 centipoise at 350.degree. F. (175.degree. C.).
EXAMPLE 5
[0071] An adhesive composition was prepared by blending 40 parts by
weight of the linear water-dispersible polymer prepared as in
Example 1 with 60 parts by weight of the branched water-dispersible
polyester of Example 2 and the properties of the adhesive
composition determined as in Example 3. The adhesive chips were
dispersed in hot water as in Example 3 within 15 minutes. The
adhesive had good repulping properties, a Tg of 4.2.degree. C., a
weight average molecular weight of 7,622, a number average
molecular weight of 1,715 and a viscosity of 2,500 centipoise at
350.degree. F. (175.degree. C).
EXAMPLE 6
[0072] An adhesive composition was prepared by blending 30 parts by
weight of the linear water-dispersible polyester prepared as in
Example 1 with 70 parts by weight of the branched water-dispersible
polyester of Example 2 and the properties of the adhesive
composition determined as in Example 3. The adhesive chips were
attempted to be dispersed in hot water as in Example 3, however,
only partial dispersion occurred. The adhesive had marginal
repulping properties, a Tg of 4.4.degree. C., a weight average
molecular weight of 7,316, a number average molecular weight of
1,831 and a viscosity of 2,490 centipoise at 350.degree. F.
EXAMPLE 7
[0073] Cut 0.9 to 1.7 grams of a branched sulfopolyester having an
inherent viscosity of 0.6 and a Brookfield Thermosel molten
viscosity @ 177.degree. C. of around 350,000-550,000 cps @
177.degree. C. Dip coated each particle of polyester into a molten
bath of 1,4,-Cyclohexane dimethanol dibenzoate. Approximate
addition of dibenzoate to the branched sulfopolyester was 1.1 to
1.7 weight percent. The above particles were then placed in a
3-inch wide corrugated tube with a tin plate placed on top of the
material with a 500-gram weight. The test assembles was then placed
in a 105-110 F forced air oven for 9 days. After nine days the
coated polyester particles were immediately examined after removal
from the oven for free flowing non-tacky appearance. The particles
tested in this experiment appeared to be free flowing.
EXAMPLE 8
[0074] The branched sulfopolyester of example 2 with an inherent
viscosity of 0.40 dL/g was coated with approximately 1.1 to 1.7% of
1,4-cyclohexanedimethanol dibenzoate. This coated sulfopolyester
was then compounded into a hot melt adhesive, along with
conventional additives such as an aromatic hydrocarbon tackifier
and additional 1,4-cyclohexane dimethanol as a set time modifier,
along with conventional antioxidant stabilizers. The contents of
the material, and the physical properties of the material, are
reported in Table 1.
1TABLE 1 Wt. Percent (of total Component composition weight)
Component Supplier The branched 70 Eastman Chemical sulfopolyester
of example Company 2 coated with 1.1 to 1.7% CHDM Dibenzoate Nevex
100 (an aromatic 20 Neville Chemical modified hydrocarbon resin)
Irganox 1010 (a hindered 0.3 Ciba-Geigy phenol antioxidant)
[0075] Physical Testing:
[0076] Viscosity @ 177.degree. C. 18,450 cp
[0077] RBSP C (ASTM E-28) 102
[0078] Water Dispersibility 100%,within 4 hrs @ RT, 1 gm of hot
melt to 100 ml of water.
[0079] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the scope or spirit of the invention. Other
embodiments of the invention will be apparent to those skilled in
the art from consideration of the specification and practice of the
invention disclosed herein. It is intended that the specification
and examples be considered as exemplary only, with a true scope and
spirit of the invention being indicated by the following
claims.
* * * * *