Note: Descriptions are shown in the official language in which they were submitted.
NON-AQUEOUS COATING CO~POSIT:I:ONS FE~O~ POLYEl'}IYLENE TEREPHTH~I~TE
W. Lesney
M. Rao
R. Tomko
D. Sayre
BACR:GROUND OF THE INVENTION
This invention relates to novel non-aqueous coating
compositions which utilize polyethylene terephthalate (PET) as a
raw material for producing the ~ilm-forming resin for such
coatings. Most preferablyr the PET is recycled or reclaimed PET
from plastic articles such as two-liter beverage bottles.
Plastics such as PET account for about 7-8 weight percent, and
about 20 volume percent, of the world's solid waste. As a result,
much legislation has been proposed and/or adopted requiring the
recycling of plastics.
PET is the primary ingredient in plastic articles such as two-
liter beverage bottles and the like. In the U.S., PET is the
plastic most often recycled. The bigyest uses for recycled PET are
as fibers in carpeting and insulation. Recycled PET is also used
in bathroom equipment and blow-molded bottles.
Processes for recycling PET beverage bottles into usable raw
materials for manufacturing unsa~urated polyester resins are known.
For example, Eastman Chemicals Publication No. N-262A entitled
Unsaturated PolYester Resins Based on Reclaimed Polyethylene
Ter.~h~h~l3~L_~ ET) Bev _aqe Bottl~es, Calendine et al. (1984),
teaches a process for convertlng PET beveraye bottles into useful
intermediates for the synthesis of unsaturated polyesters. The
unsaturated polyesters are further taught as useful as raw
materials for producing unrelnforced clear castings and fiber-
glass reinforced laminates.
A second Eastman Chemicals Publication~ No. N-292B, entitled
Aromatic Polyols From Reclai~ied Polyethylene Terephthalate, (1987)
teaches the reclamation of PET for production of aromatic polyester
polyols which are useful in making rigid polyurethane
polyisocyanurate foams.
U.S. Patent 4,223,068 (Carlstrom et al.) teaches the use of
the digestion product of polyalkylene terephthalate scraps with
organic polyol for the production of rigid polyurethane foams.
U.S. Patent 4,417,001 (Svoboda et al.) teaches the production
of low smoke isocyanurate modified polyurethane foams which are
prepared from polyols which are the digestion product of digesting
polyalkylene terephthalate scraps and orcJanic polyols.
lS U.S. Patent 4,048,104 (Svoboda et al.) teaches the preparation
of polyisocyanate prepolymers and polyurethane adhesives and foams
wherein the prepolymers are prepared by reacting organic
polyisocyanate with polyols which are the digestion product of
polyalkylene terephthalate scraps and organic polyols.
. .
SUMMARY OF THE INVENTION
This invention relates to novel non-aqueous coating
eompositions which utili.ze PET as a raw material for producing the
film-forming resin for such coatings. Preferably, the present
invention relates to non-aqueous coatlngs derived from reclaimed
PET and to a process for producing such coa-tlngs. Using reclaimed
PET benefits the environmen-t by reducing the amount of solid waste
dumped at landfills. Using reclaimed PEI' benefits this process in
that it is a relatively inexpensive raw material which, as is shown
herein, produces an excellent non aqueous coating composition.
In accordance with the present invention, PET resin (or an
equivalent polyalkylene terephthalate resin), typically having a
structure as shown in Figure I:
'-' o O
- 10 Figure I OH ~ CH2CH2-0-C- ~ -C-O~ C~2CH20H
n>100
is first digested into lower molecular weight polymeric units
through an acidolysis reac-tion. The digestion product of the
acidolysis reaction is then further reacted with a hydroxy-
functional reactant to produce an exceptional resin composition for
coating compositions. By varying the amounts and types of acid or
hydroxy-fullctional reactants according to the teachings herein,
one can formulate a variety of coatings systems including high acid
value, ~ater-reducible coatings and low acid value, solvent-based
coatings. Additionally, further chemical modifications to either
type of system are applicable and are further exemplified herein.
Accordingly, it is an object of this invention to teach the
use of polyethylene terephthala-te as a raw material for the
production oE coating compositions.
It is a ~urther object o~ this inven-tion ~o teach non-aqueous
coating compositions which utilize reclaimed PET as a raw material.
These and other objects will become more readily apparent from
the detailed description, examples and claims which follow below.
DETAILED DESCRIPTION OF T~E INVEN~XON
As stated above, the present invention relates to novel non-
aqueous coating compositions comprising PET as the startingmaterial for the production of a film-forming resin.
1. PET SOURCE
The actual source of PET usable herein is not of critical
importance to this invention. "Virgin" PET, that is P~T which is
commercially produced specifically as a raw material, is acceptable
from a chemical standpoint for use herein. Likewise, recycled or
reclaimed PET is acceptable from a chemical standpoint. At the
time of this application, there are advantages to the environment
(reduction of solid waste) and to the economics of this process
(recycled PET is much less expensive than virgin PET) by using
recycled or reclaimed PET; and, there are no performance
disadvantages to using recycled PET versus virgin PET. As a
consequence, recycled or reclaimed PET is a pre~erred starting
material though it should be appreciated that any source of PET is
acceptable.
Typically, the sources for PET are many and variel. One
source of either virgin or recycled PET is materlal from PET
polymer manufacturers. A second source of PET is excess PET from
the operations of the beverage bottle mamufacturers. A third
source is private entrepreneurs dealing in reclaimed PET. A fourth
source is community reclam~tio~ and recycling centers. A preferred
source of PT is recycled PET beverage bottles.
For purposes of this invention, the PET should be provided in
a comminuted form. It can be flaked, granulated, ground to a
powder or pelletized. Preferred is flaked PET. The only
constraint placed on the PET at this point is that it is relatively
pure; that is, there should not be a level of impurities above
about one (1) weight percent nor should there be any appreciable
level of impurities which are chemically reactive within this
process. PET which is acceptable for use herein should have the
following characteristics:
Intrinsic Viscosity 0.65-0.75
Moisture <1.0%
Colored PET content <400ppm
High Density Poly-
ethylene (HDPE) <lOOppm
Adhesives <SOOppm
Aluminum <lOppm
20 CHEMISTRY OF PET
PET is comprised of repeating units of ethylene glycol and
terephthalic acid connected by ester linkages. Figure I, above,
shows a typical PET molecule. Each repeating unit of PET has a
weight average molecular weight of 192 with one equivalent of
ethylene glycol and one equivalent of terephthalic acid. By
reacting PET with an acid, it is possible to reduce the average
chain leng-th of the PET molecules. The chemistry of PET is such
that an equilibrium exists between PET, water, ethylene glycol (EG)
and terephthalic acid (TPA). This equilibrium makes it possible
to substantially reverse -the polymeriza-tion process and
depolymerize PET into its starting materials. The Eastman Chemical
publications cited above refer to the process of depolymerizing PET
as "glycolysis". That process comprises the catalytic reaction of
PET with a polyol. In contrast, the present inven~ion does not use
Aydroxy-functional materials, rather, the present inventi.on uses
acids and/or anhydrides to accomplish similar results.
a. Acidolysis of PET
It ls possible to reverse the PET equilibrium and reduce the
average chain length of PET with an acid- or anhydride-functional
. .
material. The process of "acidolysis" of PET comprises the
reaction of PET with an acid- or anhydride-functional material.
a.1. Acids for use in Acidoly~is Rea~tion
Suitable acid-functional materials include mono-functional
acids such as benzoic, crotonic and sorbic acids; and acids having
an acid functionality on average of at least two, such as phthalic
acid, succinic acid, adipic acid, azelaic acid, maleic acid,
fumaric acid, trimellitic acid, trimesic acid, naphthalene
dicarboxylic acids, carboxy-terminated polybutadiene, benzophenone
tetracarboxylic dianhydride, 4,4'-dicaboxy diphenoxy ethane, and
the hydroxy carboxylic acids of piralactone. Other suitable acids
include the saturated acids such as butyric, caproic, caprylic,
capric, lauric, myristic, palmitic, stearic, 12-hydroxystearic,
arachidic, behenic and lignoceric acids; the unsaturated acids such
as palmitoleic, oleic, ricinoleic, linoleic, linolenic,
eleostearic, licarlc, gadoleic and eracic acids; and the oils (and
their ~atty acids) SUCII as canola, rapeseed, castor, dehydrated
castor, coconut, coffee, corn, cottonseed, fish, lard, linseed,
oticica, palm kernal, peanut, perilla, safflower, soya, sunflower,
tallow, tung, walnut, vernonia, tall and menhaden oils; and blends
and mi.xtures of natural and synthetic oils and :Eatty acids,
5 particularly those oils and fatty acids with high iodine numbers.
a. 2 . Anhydrid~s for use ill Acidolysis Reaction
Representative anhydrides include, phthal ic anhydride,
3-nitrophthalic anhydride, 4-nitrophthalic anhydride,
3-flourophthalic anhydride, 4-chlorophthalic anhydride,
10 tetrachlorophthalic anhydride, tetra bromophthalic anhydride,
tetrahydrophthalic anhydride, hexahydro phthalic anhydride,
methylhexahydrophthalic anhydride, succinic anhydride,
dodecenylsuccinic anhydride, octylsuccinic anhydride, maleic
anhydride, dichloromaleic anhydride, glutaric anhydride, adipic
15 anhydride, chlorendic anhydride, itaconic anhydride, citraconic
anhydride, endo-methylenetetrahydrophthalic anhydride,
cycl oh exane~ 1, 2 -d i carboxyl i c anhydride,
4 -cyc 1 ohexene- 1, 2 -dicarboxyl ic anhydride,
4-methyl-4-cyclohexene-1,2-dicarboxylic anhydride,
2 O 5 - n o r b o r n e n e - 2 , 3 - d i c a r b o x y 1 i c a n h y d r i d e ,
1, 4-cyclohexadiene-1, 2-dicarboxyl ic anhydride,
1,3-cyclopentanedicarboxylic anhydride, diglycolic acid anhydride,
and -the 1 ike .
Other useful anhydrides include those anhydrides having a free
25 carboxyl. group in addition to the anhydride group such as
trimellitic anhydride, aconitic anhydride, 2,6,7-naphthalene
tricarboxylic anhydride, 1,2,4-butane tricarboxylic anhydride,
1,3,4-cyclopentane tricarboxylic anhydride, and the like.
It should be appreciated that other acids and anhydrides
should be considered equivalents of those named herein.
T~e acid- or anhydride functional material will generally have
a number average mol~cular weight below about 2000. Preferably the
acid- or anhydride-functional material will have a number average
~ molecular weight of below about 400. Typical number average
molecular weights of these materials will range from about 96 to
about ~00.
Especially preferred acids and anhydrides include the
vegetable fatty acids described above and trimelletic anhdyride.
Optionally, a catalyst can be used for the acidolysis
reaction. If used, suitable catalysts for acidolysis of PET
include the traditiorlal transesterification catalysts including
stannous octoate, calcium hydroxide, lithium hydroxide, barium
hydroxide, sodium hydroxide, lithium methoxide, manganese acetate
tetrahydrate, and dibutyl tin oxide (tradename Fascat, available
from M~T Chemicals). Most preferred is dibutyl tin oxide. If
used, the catalyst should be present in an amount of from about
0.2 weight % to about 1.5 weight ~ based upon the total weight of
the PET and acid-functional material.
When PET and an acid- or anhydride-functional material are
reacted together in the presence of the catalyst (optional) and
heat, the hi.gh molecular weight PET molecule is broken down into
shorter chain fragments. This is accomplished through chain attack
and exchange by the acid with the terephthalic acid units of the
PET molecule. This attack and exchange continues -to occur until
a new equilibrlum is established between the PET, the shorter chain
length PET~ the shorter chain length PET substitutecl with-the acid,
the acid-functional material ancl terephthalic acid. Figure II
shows the typical products of acidolysis of PET with an acid-
functional material:
O O O
Il 11 !1
Figure II HO-R-C-O-R'-OH + HO-C-R"-C--OH
<--> (INTERMEDIATE) <-->
O O O
Il 11 11
HO-R-C-OH -t HO-R'-O-C-R"-C-OH
Subsequent to acidolysis, all remaining PET fragments and products
in equilibrium therewith are acid-functional. As described further
below, they can be reacted with hydroxy-functional materials and
the like to form excellent coating compositions.
b. Further Reactions of the Acidolysis Products
As discussed briefly above, the product of the acidolysis
reaction is further reacted to produce a polyester product useful
in a coating composition. Since the acidolysis reaction products
are acicl-functional, they can be further reacted with alcohols
including those taugh-t below to obtain exceptional coatings
products. By controlling the levels ancl amounts of reactants, as
discussecd helow, one can formulate either high acid value or low
acid value systems erom the aciclolysis reaction products. The
products of such reactions include alkyds and polyesters which can
be air or bake dried or which carl be further mixed, reacted or
modified to create dispersions of emulsion polymers using the
alkyds or polyesters as dispersing media and acrylic modified
alkyds and polyesters.
b.1~ Alcohol~
Typically, the alcohols will have number average molecular
weights of below about 4000 and typical number average molecular
-~ weights will range from about 30 to about 4000, and especi.ally 100
to about 400. Methods of preparing alcohols are well known in the
art and the method of preparation of the alcohols is not critical
to the practice of this invention.
Suitable alcohols include the Cl-C22 linear and branched
saturated and unsaturated alcohols including, for example,
methanol, ethanol, propanol, butanol, hexànol, linoleyl alcohol,
trimethylolpropane diallyl ether, allyl alcohol, 2--mercapto ethanol
and the like. Additionally, ~seful alcohols include the
hydroxy-functional polyethers, polyesters, polyurethanes,
polycaprolactones, etc. as generally discussed in Sections b.l.a.
through b.l.e. below.
b.~.a. Saturated and unsaturated polyols include
: glycerol, castor oil, ethylene glycol, dipropylene glycol,
2,2,4-trimethyl 1,3-pentanediol, neopentyl glycol, 1,2-propanediol,
1,3-propanediol, 1,4~butanedlol, 1,3-butanediol, 2,3-butanediol,
1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol,
aisphenol A tetraethoxylate, dodecahydro Bisphenol A, 2,2'-thio
diethanol, dimethylol propionic acid, ace.tylenic diols, hydroxy-
1~
.
terminated polybutadiene, 1,4-cyclohexanedime~hanol,
1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol,
1,4-bis(2-hydroxyethoxy~cyclohexane, trimethylene glycol, tetra
methylene glycol, pentamethylene glycol, hexamethylene glycol,
decamethylene glycol, diethylene glycol, triethylene glycol,
tetraethylene glycol, norbornylene glycol, 1,4-benzenedimethanol,
1,4-benzenediethanol, 2,4-dimethyl-2-ethylenehexane-1,3-diol,
2-butene-1,4-diol, and polyols such as trimethylolethane,
trimethylolpropane, trimethylolpropane monoallyl ether,
10 trimethylolhexane, triethylolpropane, 1,2,4-butanetriol, glycerol,
pentaerythritol, dipentaerythritol, etc.
b.l.b. Polyether polyols are well known in the art and
are conveniently prepared by the reaction of a diol or polyol with
the corresponding alkylene oxide. These materials are commercially
available and may be prepared by a known process such as, for
example, the processes described in Encyclopedia of Chemical
Technoloqy, Volume 7, pages 257-262, published by Interscience
Publishers, Inc., 1951. Representative examples include the
polypropylene ether glycols and polyethylene ether glycols such as
those marketed as NIAX Polyols from Union Carbide Corporation.
b~l.a. Another useful class of hydroxy-functional
polymers are those prepared by condensation polymerization reaction
techniques as are well known in the art. Representative
condensation polymerization reactions include polyesters prepared
by the condensation of polyhydric alcohols and polycarboxy:lic acids
or anhydrldes, with or without the inclusion of drying oil,
11
semi-dryiny oil, or non-dryi.ng oil fatty acids. By adjusting the
stoichiometry of the alcohols ancl the acids while maintaining an
excess of hydroxyl groups, hydroxy-functional polyesters can be
readily produced to provide a wide range of desired molecular
weights and performance characteristics.
The polyester polyols are derived from one or more aromatic
and/or aliphatic polycarboxylic acids, the anhydrides thereof, and
one or more aliphatic and/or aromatic polyols. The carboxylic
acids include the saturated and unsaturated polycarboxylic acids
and the derivatives thereof, such as maleic acid, fumaric acid,
succinic acid, adipic acid, azelaic acid, and dicyclopentadiene
dicarboxylic acid. The carboxylic acids also include the aromatic
polycarboxylic acids, such as phthalic acid, isophthalic acid,
terephthalic acid, etc. Anhydrides such as maleic anhydride,
phthalic anhydride, trimellitic anhydride, or Nadic Methyl
Anhydride (brand name for methyl bicyclo [2.2.1]
heptene-2,3-dicarboxylic anhydride isomers) can also be used.
Representative saturated and unsaturated polyols which can be
reacted in stoichiometric excess with the carboxylic acids to
produce hydroxy-functional polyesters include the diols taught in
b.l.a. and b.l.b., above.
Typically, the reaction between the polyols and the
polycarboxylic acids is conducted at about 120C to about 200C in
the presence of an esterification catalyst such as dibutyl tin
oxide.
b.l.d. AdAitionally, hydroxy-functional polyrners can be
prepared by the ring opening reaction of epoxides and/or
polyepoxides with primary or, preferably, secondary amines or
polyamines to produce hydroxy-functional polymers. Representative
amines and polyamines include ethanol amine, N-methylethanol amine,
dimethyl amine, ethylene diamine, isophorone diamine, etc.
Representative polyepoxides include those prepared by condensing
a polyhydric alcohol or polyhydric phenol with an epihalohydrin,
such as epichlorohydrin, usually under alkaline conditions. Some
of these condensation products are available commercially under the
designations EPON from Shell Chemical Company, and methods of
preparation are representatively taught in U.S. patents 2,592,560;
2,532,985 and 2,694,694.
b. 1. e. Other useful hydroxy-functional polymers can be
prepared by the reaction of an excess o~ at least one alcohol, such
as those representatively described above, with isocyanates to
produce hydroxy-functional urethanes. Representative mono-
functional isocyanates include allyl isocyanate and tolulyl
isocyanate. Representative polyisocyanates include the aliphatic
compounds such as ethylene, trimethylene, te-tramethylene,
pentarnethylene, hexamethylene, 1,2-propylene, 1,2-butylene,
2,3-butylene, 1,3-butylene, ethylidene and butylidene
diisocyanates; the cycloalkylene co~pounds such as 3-isocyanato
methyl 3,5,5-trimethyl cyclohexylisocyanate, and the
2S 1,3-cyclopentane, 1,3-cyclohexane, and 1,2-cyclohexane
diisocyanatesi the aromatic compounds such as m-phenylene,
13
p-phenylene, 4,4'-diphenyl, 1,5-naphthalene and 1,4-naphthalene
diisocyanates; the aliphati.c-aromatic compouncls such as
4,4'-diphenylene methane, 2,4- or 2,6-toluene, 4,4'-toluidine, and
1,4-xylylene diisocyanates; benzene 1,3-bis (l-isocyanato-1-methyl
S ethyl); the nuclear substituted aro~atic compounds such as
dianisidine diisocyana-te, 4,4'-diphenylether diisocyanate and
chlorodiphenylene diisocyanate; the triisocyanates such as
triphenyl methane-4,4',4 "-triisocyanate, 1,3,5-triisocyanate
benzene and 2,4,6-triisocyanate toluenei and the tetraisocyanates
such as 4,4'-diphenyl~dirnethyl methane-2,2'--5,5'-tetraisocyanatei
the polymerized polyisocyanates such as -tolylene diisocyanate
dimers and trimers, and other various polyisocyanates containinq
biuret, urethane, and/or allophanate linkages. The isocyanates and
the alcohols are typically reacted at temperatures of 25C to about
150C to form the hydroxy-functional polymers.
Especially preferred hydroxy-functional materials in the
practice of this invention are mono-functional alcohols such as
trimethylolpropane diallyl ether and allyl alcohol; an~d diols and
triols such as ethylene glycol, dipropylene glycol, 2,2,4-trimethyl
1,3-pentanediol, neopentyl glycol, 1,2-propanediol,
1,3-propanediol, 1,4-butanediol, 1,3-~utanediol, 2,3-butanediol,
1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol,
1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol,
1,3~cyclohexanedimethanol, 1,~ bis(2-hydroxyethoxy)cyclohexane,
trimethylene glycol, tetra methylenecJl.ycol, pentamethyl.ene glycol,
hexarnethylene glycol, decamethylene glycol, diethylene glycol,
1"
triethyle~e gLycol, tetraethylene glycol, norbornylene glycol,
1,4 -benzenedimethanol, 1,4-benzenediethanol,
2,4-dimethyl-2-ethylenehexane-1,3-diol, 2-butene~1,4-diol, and
polyols such as trimethylolethane, trimethylolpropane,
trimethylolpropane monoallyl ether, trimethylolhexane,
triethylolpropane, 1,2,4-butanetriol, glycerol, pentaerythritol,
dipentaerythritoli and mixtures thereof.
Most preferred are trimethylolpropane diallyl ether, propylene
glycol, ethylene glycol, diethylene glycol, ancl mixtures thereof.
It should be appreciated that other alcohols should be considered
equivalents of those named herein.
c. High and Low Acid Value Products using the Acidolysis
Reactio~ Products
As stated above, the acidolysis reaction products can are
further reacted with alcohol to produce either high or low acid
value products. For purposes of the present invention, the term
"high acid value" is meant to be those compositions having acid
values greater than about 30. The term "low acid ~alue" is meant
to be those compositions having acid values lower than about 20.
; 20 Compositions having acid values between about 20 and about 30 tend
to exhibit characteristics of both high and low acid value products
and, thus, are not categorized as either high acid value or low
acid value, although it should be appreciated that with some trial
and error such compositions may be acceptable in either category.
As a guideline, in order to formulate an acidolysis reaction
product to a high acid value o~ between about 55 and about 65, the
following stoichiometric proportions (in moles oE equivalents) of
materials should be used. For each mole of PET used, from about
1.0 to about 1.5 moles of acid/anhydride should be used in the
acidolysis reaction, followed by further reactlon with about 0.05
to about 0.2 moles of OH. Preferably, the moles of acid to PET
should be about 1.0:1 to about 1.1.2:1 and the moles of OH to PET
should be about 0.05:1 to about 0.1:1 for such higher acid value
products~
In order to formulate an acidolysis reaction product to a low
acid value of less than about 20, the following stoichiometric
proportions ~in moles of equivalents) of materials should be used.
For each mole of PET used, from about 1.0 to about 1.5 moles of
acid/anhydride shvuld be used in the acidolysis reaction, followed
by further reaction with about 0.1 to about 0.3 moles of OH.
Preferably, the moles of acid to PET should be about 1:1 to abou-t
1.2:1 and the moles of OH to PET should be about 0.15:1 to about
0.25:1.
d. Fi~al Coati~g Products
The products of Section 2.c. can be used by themselves, in
combination with other well known coatinys additives, including
pigments, flow agents, catalysts, diluents, solvents, ultraviolet
light absorbers, and the like, or can be further mixed, reacted or
modified as described below.
The high acid value products (that is, acid values greater
than about 30) of Section 2.c., or such products in combination
with the above-described additives, can be dispersed or reduced in
16
water once neutralized with a weak base solution such as a tertiary
a~ine in water. Neutralization techniques are well known in the
coatings art. In a preferred e~bodlment, the high acid value
products of ~ection 2.c. can be reduced in water and thereafter
serve as the stabilizing media for the emulsion polymerization of
acrylic and other ethylenically unsaturated monomers, including
acrylic addition monomers, oligomers and polymers; particularly one
or more alkyl esters of acrylic acid or methacrylic acid;
optionally together with one or more other ethylenically
unsaturated monomers.
Suitable acrylic esters include methyl (meth)acrylate, ethyl
~meth~acrylate, propyl (meth)acrylate, butyl (meth)acrylate,
hydroxy ethyl (meth)acrylate, 2-ethyl hexyl (meth)acrylate,
acrylonitrile, acrylamide, vinyl polymers such as polymers of vinyl
esters of inorganic or organic acids, including vinyl chloride,
vinyl acetate, vinyl propionate, vinyl toluene, etc., styrene, and
mixtures thereof.
Emulsion polymerization reaction conditions are well known in
the art and can include the procedures taught in U.S. Patent
4,116,903, incorporated herein by reference as well as the
procedures taught in the Examples below.
The low acid value products (that is, acid values less than
about 20) of such section, or such products in combination with the
above-described additives, can be reduced in solvents such as
xylene, toluene, benzene, mineral spirits and the li~e. Such
products can then be allowed to air dry or Eorced to dry by baking
as is ~ell known in the art. A melamine, or equivalent, agent
would pre~erably be added to Pacilitate drying in the bake dry
systems. In a preferred embodiment, the low acid value products
of Section 2.c. can be directly modified with acrylic monomers,
S oligomers and polymers to produce air dry, bake and water-reducible
coatings.
Suitable acrylic monomers, oligomers and polymers include
those acrylic, vinylic and ethylenically unsaturated materials
taught to be useful wi.th the high acid value products as well as
the acrylic acids themselves such as acrylic acid, methacrylic acid
and itaconic acid.
In another preferred embodiment, either the high or the low
acid value products of Section 2.c. can be further modified by
direct acrylic modifica~ion. Qirect acrylic modification is
typically conducted under conditions also well known in the art,
including the procedures taught in U.S. Patents 4,735,995 and
4,873,281, incorporated herein by reference, as well as by the
~ procedures taught in the Examples below. ~
-;~ When acrylically modifying the low acid value products, the
incorporation of a high level of acid-functlona1 acrylic materials
will enable the final, acrylic-modified coating product to be
reducible in water or other aqueous systems. Generally, amounts
of acid--functional acrylic materials greater than about l.0~ by
weight o the total amount o~ acr~lic and other ethylenically
unsaturated materials will result in a coating composition which
.
is water reducib1e. Amounts less than the above will generally
result in coatings which are not water reclucible.
The coatings of this invention may typically be applied to
any substrate such as metal, plastic, wood, and glass, by brushing,
dipping, roll coatinq, flow coating, spraying or other method
conventionally employed in the coating industry.
Representative opacifying pigments include white pigments such
as titanium dioxide, zinc oxide, antimony oxide, etc. and organic
or inorganic chromatic pigments such as iron oxide, carbon black,
phthalocyanine blue, etc. The coatings may also contain extender
pigments such as calcium carbonate, clay, silica, talc, etc.
The following examples have been selected to illustrate
specific embodiments and practices of advantage to a more complete
understanding of the invention. Unless otherwise stated, "parts"
means parts~by-weight and "percent" is percent-by-weight.
EX~MPLE I: ACIDOLYSIS OF PET
A high acid value, water reducible resin was prepared
according to the following procedure:
A 31, 4-necked round bottom flask equipped with inert gas,
mechanical stirrer, Barrett tube and Friedrich's condenser was
charged with 606.64g of polyethylene terephthalate, 887.6g of high
content linoleic fatty acid (Prifac 8960), 3.3g of dibutyl tin
oxide catalyst and 55g xylene. The contents were heated to 490F
and held until all contents had melted and a clear solution was
obtained. The solution was cooled to 325F and 70.65~ of
trimethylolethane was added. The contents were heated to 465F and
19
held for an acld value of between 30-35. Once reached, heat was
removed and the contents allowed to cool. The final resin product
had an NVM of 98.8, acid value of 31, Mz of 4424, Mw of 2367, Mn
of 1389 and Pd of 1.70.
EXAMPLE II: ACIDOLYSIS OF PET
A low acid value resin was prepared according to the following
procedure:
A 31, 4-necked round bottom flask equipped with inert gas,
mechanical stirrer, Barrett tube and Friedrich's condenser was
charged with 608.64g of polyethylene terephthalate, 887O6g of high
content linoleic fatty acid (Prifac 8960), 3.3g of dibutyl tin
oxide catalyst and 55g xylene. The contents were heated to 490F
and held until all contents had melted hnd a clear solution was
obtained. The solution was cooled to 325F and 240g of
trimethylolethane was added. The contents were heated -to 460F and
held for an acid value of less than 12. Once reached, heat was
removed and the contents allowed to cool. The final resin product
had an NVM of 97.9, viscosity of 12,200cps (using Brookfield LVT~3,
12 rpm), acid value of 3.8, Mz of 8019, Mw of 3619, Mn of 1639 and
Pd of 2.20.
EXAMPLE III: ACIDOLYSIS OF PET
A low acid value resin was prepared according to the following
procedure~
A 31, 4-necked round bottom flask equipped with inert gas,
mechanical stirrer, Barrett tube ancl Friedrich's condenser was
charged with 764.72g of polyethylene terephthalate, 1124.42g of
tall oil fatty acid, 9.5g of dibutyl tin oxide catalyst and 55g
xylene. The contents were heated to 490F and held until all
contents had melted and a clear solution was obtained. The
solution was cooled to 325F and 301.62g of trimethylolethane was
added. The contents were heated to 465F and held for an acid value
of less than 10. Once reached, heat was removed and the contents
allowed to cool. The final resin product had an NVM of g8.3,
viscosity of 11,200cps (using Brookfield LVT~3, 12 rpm), acid ~alue
of 6.6, Mz of 4464, Mw of 2522, Mn of 1418 and Pd of 1.78.
EXAMPLE IV: DIRECT ACRYLIC MODIFICATION
511g of the resin of Example II and 250g of Propasol
(propylene glycol monobutyl ether) were charged to a reaction
vessel and heated to about 140C. Added to the vessel over a 3.5
hour period was 304.0g of methyl methacrylate, 50g of metha~rylic
acid, 100.0g of hydroxy ethyl acrylate, and 46g of ethyl hexyl
acrylate. A second feed of 12.5g of t-butyl perbenzoate ~2.5% in
Propasol) was added over the same time period. Upon complete
addition of both feeds, a chase of 2.3g t-butyl perbenzoate in 30g
of Propasol was added over a 1.5 hour time period~ Heat was
removed and the contents of the vessel filtered.
EXAMPLE V: DISPERSION IN WATER
The composition of Example V was added to 1000g of water and
50g of tri.ethylamine. It had an NVM of 35.5%, a pH of 8.05 and a
viscosity of 2150cps (Brookfield LVTK3, 12 rpm).
25 EXAMPLE VI: BAKE DRY ENAMEI. FORMtlLA
A resin prepared according to the procedure of Example I can
be formulated to a bake dry coating having PVC 18.0, NVM 50 1,
weight per gallon 10.05 lbs/gal and VoC of 1.9~ lbs~gal as follows:
In a high speed disperser, yrind the following:
191.3g Resin of Exampl~ I
40.7 Propasol P
5.9 Dimethylethanolamine
Add 228.5 Rutile titanium dioxide
32.9 Water
10 Run -to 7H lHegman Grind)
Stabilize 135.5 Water
Thindown 100.6 Resin of Example I
36.3 Propasol P
82.7 Melamine
5.4 Dimethylethanolamine
12.8 2-butoxy ethanol (Butyl Cellosolve)
232.2 Water
EXAMPLE VII: BAKE DRY ENAMEL FORMULA
A resin prepared according to the procedure of Example II can
be formulated to a bake dry coating having PVC 18.2, NVM 81.8,
weight per gallon 11.7 lbs/gal and VOC of 2.15 lbs/gal as follows:
In a high speed disperser, grind the following:
172.0g Resin of Example II
100.0 Propasol P
428.0 Rutile titanium dioxide
Run to 7H (Hegman Grind)
. Stabilize 82.3 Propasol P
Thindown 236.7 Resin of Example II
134.2 Melamine
30 24.3 Propasol P
22
