Note: Descriptions are shown in the official language in which they were submitted.
~ 1 1 336735
` CO~TING COMl~OSITI~NS
This invention relates to coating compositions and to
their production; also to novel polyanhydrides for use
therein.
US Patent 445294~ describes a two-pack coating com-
position comprising a hydroxy component and an anhydride
component, in which the hydroxy component is a polymer
having at least two free hydroxyl groups per molecule and
also has in its molecule amine groups for accelerating the
curing reaction between the hydroxy groups and the an-
hydride groups, and the anhydride component is a polymer
having at least two cyclic carboxylic acid anhydride groups
per molecule. In a less preferred modification the amine
groups are present in a separate amine compound rather than
on the molecule of the hydroxy component. The coatings of
US Patent 4452943 have the advantage that they are
ambient-temperature-curing without the use of toxic
isocyanates and have been used successfully as finish coats
for automobiles, particularly in re-finishing, `and as
paints for yachts.
European Patent Application 134691 describes a three-
component coating composition comprising a compound having
at least two hydroxy groups, a compound having at least
two anhydride groups and a compound having at least two
epoxide groups.
European Patent Application 259172 describes a coating
composition comprising an anhydride polymer and a polymer
containing hydroxyalkylamino, hydroxyalkoxyalkylamino,
hydroxy-substituted acyloxyalkylamino, hydroxy-substituted
polyacyloxyalkylamino, mercaptoalkylamino or oxazolidino
groups. One of the polymers comprises a flexible polymer
chain and has its functional groups present as terminal
*
- . - 2 - 1336735
groups at the end of the flexible polymer chain.
US Patent 3984382 describes a modified cationic
vinyl polymer suitable for electrocoating and prepared by
5 reacting a copolymer of maleic anhydride, styrene and an
alkyl acrylate with an amino-alcohol and/or a di-functional
amine until the modified polymer has no residual anhydride
rings, and reacting the product with a monoepoxy compound.
US Patents 3449250 and 3329658 describe an additive
which imparts stability and detergency to mineral oil. The
additive comprises a copolymer of maleic anhydride and an
alpha-olefin which has been partially esterified with an
aliphatic alcohol to make the copolymer oil-soluble and in
which substantially all of the remainder of the carboxyl
15 groups are imidized.
German Patent 1595333 describes water-soluble
polyelectrolytes useful as flocculating agents and retention
aids in paper-making and made by reacting a copolymer of an
ethylenically unsaturated carboxylic anhydride with a
20 polyamine containing only one primary or secondary amino
group, and reacting the reaction product with an
epihalohydrin and/or a diepoxide.
A coating composition according to the invention
comprises a hydroxy component having at least two free
25 hydroxy groups per molecule and an anhydride component having
at least two cyclic carboxylic acid anhydride groups per
molecule, at least one of the hydroxy component and the
anhydride component being a film-forming polymer, said
composition containing a catalytically effective amount of
30 amine groups for accelerating the curing reaction between the
hydroxy groups of the hydroxy component and the anhydride
groups of the anhydride component, which contains the said
amine groups as pendent groups in its molecules. The
anhydride component, having at
`t~
~ 1 336735
least two cyclic carboxylic anhydride groups per molecule,
is characterised in that the polyanhydride contains pendent
amine groups, the proportion of amine groups to cyclic car-
boxylic acid anhydride groups being no more than 4:1 and
the content of free carboxylic acid groups, if any are
present, being less than 200 mole per cent based on the
amine groups.
The proportion of amine groups to cyclic carboxylic
acid anhydride groups in the polyanhydride is preferably at
least 0.01:1 and no more than 1.5:1, most preferably
0.01:1 to 1:1. The content of free carboxyl groups is
preferably less than 100 mole per cent based on the amine
groups; most preferably, free carboxyl groups are substan-
tially absent or are present at less than 20 mole per cent
based on amine groups.
The coating compositions of the invention have ad-
vantages over those described in US Patent 4452948 and
European Patent Application 259172. The polyanhydrides of
the invention can be used in coating compositions with a
wide variety of hydroxy-functional polymers, including
unmodified commercial polymers. The coating compositions
also have improved stability against photo-degradation
compared to many of the coatings of European Patent Ap-
plication 259172. The coating compositions of the inven-
tion avoid the possibilities of environmental hazard andstickiness of the cured coating which may be encountered
using a free amine compound as catalyst.
The amine groups present in the polyanhydride are
preferably tertiary amine groups, which are the most
effective in catalysing the reaction between the hydroxy
and the anhydride groups without giving rise to side
reactions.
One preferred type of polyanhydride according to the
invention is a polymer containing cyclic carboxylic an-
~ 1 336735
hydride groups and N-(dialkylaminoalkyl)-substituted imide
groups. Such a polyanhydride can be formed by the reaction
of a polymer containing anhydride groups with a less than
stoichiometric amount of a polyamine containing a primary
amine group and at least one tertiary amine group. The
said polymer containing cyclic carboxylic acid anhydride
groups is preferably derived from an olefinically
unsaturated cyclic carboxylic acid anhydride.
The polymer containing cyclic anhydride groups can for
example be a copolymer of an olefinically unsaturated
cyclic carboxylic acid anhydride such as maleic, itaconic,
citraconic or vinylsuccinic anhydride or vinyl trimellitate
anhydride with one or more olefinically unsaturated com-
onomers such as an alpha-olefin, for example ethylene or
propylene, a vinyl comonomer, for example styrene or a
substituted styrene, vinyl acetate or vinyl chloride, or an
ester of acrylic or methacrylic acid, for example butyl
acrylate, ethyl acrylate, methyl methacrylate or butyl
methacrylate. Preferred copolymers contain 10 - 40 per
cent, most preferably 20-35 per cent, by weight ma1eic or
itaconic anhydride groups and have a molecular weight of
1500 - 30000, e.g. 4000-12000. If the coating is to be
used as a decorative top coat it may be preferred to use a
vinyl comonomer at a molar ratio of at least 1:1 with
respect to the anhydride monomer, as described in US Patent
4798745.
The polymer containing cyclic anhydride groups can
alternatively be an anhydride adduct of a diene polymer
such as maleinised polybutadiene or a maleinised copolymer
of butadiene, for example a butadiene/styrene copolymer.
The maleinised diene polymer is preferably hydrogenated to
remove residual unsaturation. Terpene maleic anhydride
copolymer resins are a further alternative. An anhydride
adduct of an unsaturated fatty acid ester, for example a
styrene/allyl alcohol copolymer esterified with an un-
saturated fatty acid and maleinised, can also be used.
~ 1 336735
The polymer containing anhydride groups can alternatively
be formed by the reaction of a polymer containing thiol
groups with an olefinically unsaturated cyclic carboxylic
acid anhydride such as maleic anhydride or itaconic an-
hydride. The polymer containing thiol groups is preferablythiol-tipped; it can for example be a multi-limbed
telechelic polymer formed by reaction of a corresponding
hydroxy-tipped polymer with mercaptoacetic acid.
Alternative anhydride-containing polymers can be
formed from hydroxy-containing polymers, for example
copolymers of hydroxyethyl acrylate or hydroxyethyl
methacrylate or styrene/allyl alcohol copolymers, by reac-
tion with a tricarboxylic compound capable of introducing
anhydride groups, for example as described in European
Patent Application 259172. A further alternative type of
polymer containing anhydride groups is an adduct of trimel-
litic anhydride and a polyol, as described in European
Patent Application 134691.
The polyamine which is reacted with the polymer
containing anhydride groups is preferably a primary/ter-
tiary diamine, for example N,N-dimethylpropane-1,3-diamine
~(CH3)2NCH2CH2CH2NH2), N,N-dimethylethylenediamine, 4-amino
-1-(diethylamino)-pentane, N,N-diethylpropane-1,3-diamine,
2-amino-pyridine, 3-amino-pyridine, 4-amino-pyridine or N-
(3-aminopropyl)-morpholine. The primary amino group reacts
with the anhydride group to form an imide group which has
the tertiary amine group in a pendent organic group at-
tached to the imide nitrogen atom. The substituted imide
groups formed generally have the formula
Z Z
O~N~O
I
X
where each Z represents a polymer residue and X is an
~ 6 l 336735
organic group containing a tertiary amino group and is
attached to the imide nitrogen atom by a carbon-nitrogen
bond. The group X can for example be an aminoalkyl group
of the form -A-NR2, where -A- is a straight or branched-
chain alkylene group preferably having 2 to 8 carbon atomsand each group R is an alkyl group preferably having 1 to 4
carbon atoms; a heterocyclic ring containing a tertiary
nitrogen atom such as 4-pyridyl; or an alkyl group sub-
stituted by a heterocyclic ring containing a tertiary
nitrogen atom such as a pyridine or morpholine ring. For
example, using N,N-dimethylpropane-1,3-diamine
-H20
Z I z + (CH3)2NCH2cH2cH2NH2
0 0 0 0 N 0
CH2CH2CH2N(cH3)2
where each Z represents a polymer residue.
The reaction between the polymer containing anhydride
groups and the diamine can for example be carried out by
heating under reflux in an organic solvent which has a
boiling point substantially higher than that of water (for
example 120 - 180C) or forms an azeotrope with water, with
water being removed by distillation during the reaction.
Examples of solvents are esters such as butyl acetate or
methoxypropyl acetate, ketones such as methyl isobutyl
ketone or aromatic hydrocarbons such as xylene. The
anhydride and amine initially react to form an acid amide
which may have limited solubility, particularly in
hydrocarbon solvents. It may be preferred to add the
diamine gradually during the reaction. Alternatively, the
reaction can be carried out as a 2-stage reaction in which
the acid amide is formed in an initial step and is heated
in a solvent, with removal of water, or with a dehydrating
~_ 1 336735
agent such as acetic anhydride or a carbodiimide such as
dicyclohexyl carbodiimide.
The proportion of polyamine reacted with the polymer
containing anhydride groups is generally no more than 0.8
mole of polyamine per mole of anhydride groups in the
polymer and is preferably no more than 0.5 moles/mole so
that the resulting polyanhydride contains at least as many
anhydride groups as N-(aminoalkyl)-substituted imide
groups. Preferably, the molar ratio of diamine to an-
hydride groups is 0.1 - 0.5:1, most preferably 0.1-
0.33: 1 .
An alternative form of polyanhydride according to the
invention can be formed from a polymer of an olefinically
unsaturated tricarboxylic acid such as aconitic acid or an
anhydride thereof by reaction with an amino alcohol,
preferably a tertiary amino alcohol such as N,N-dimethyl
ethanolamine. The reaction is carried out under conditions
such as to remove water, for example at reflux in an
organic solvent of higher boiling point than water and/or
azeotroping with water, for example using butyl acetate as
solvent.
CH2COOH
H20
25 Z I I Z ~ Z I I - CH2
COOH COOH COOH ~C ~C = O
~ ( CH 3 ) 2NCH 2CH 20H
C~OOCH2CH2N ( CH3 ~ C~COOCH2CH2N ( CH3 ) 2
Z I C Z Z IC - Z
O=C ~ ~ C = O -H 2 COOH COOH
~_~ 8 1 336735
This product containing anhydride groups and pendent
amino alkyl ester groups may have increased reactivity
with hydroxy groups.
A polymer containing anhydride groups and pendent
amine groups cannot in general be formed by the
copolymerisation of an unsaturated cyclic carboxylic acid
anhydride such as maleic anhydride or itaconic anhydride
and an unsaturated amine such as a dialkylaminoalkyl
acrylate or methacrylate. Such polymerisation forms either
a polyacid or a black charge-transfer complex as described
by Taylor and Woodward in J. Polymer Science, Part A., Vol.
1,pp 1473-1482 (1963). A polymer containing anhydride
groups and pendent amine groups can however be formed by
copolymerisation of an olefinically unsaturated dicar-
boxylic acid and an olefinically unsaturated amine,preferably a tertiary amine such as a dialkylamino alkyl
acrylate or methacrylate under conditions such as to remove
water, for example at a temperature above 100C and/or by
azeotropic distillation. The preferred olefinically
unsaturated dicarboxylic acid is itaconic acid, which can
be dissolved in a polar organic solvent such as
tetrahydrofuran. The unsaturated dicarboxylic acid solu-
tion is preferably added to the polymerisation vessel
separately from the amine monomer, which can for example be
diethylaminoethyl or dimethylaminoethyl acrylate or
methacrylate. The amine monomer can be dissolved in an
organic solvent such as an aromatic hydrocarbon, ester or
ketone, preferably together with one or more olefinically
unsaturated comonomers. The solvent for the unsaturated
dicarboxylic acid may be removed by distillation during
the polymerisation; the copolymer is more soluble in
organic solvents than the acid monomer.
A further alternative type of polyanhydride is a graft
copolymer of a polymer containing cyclic carboxylic acid
anhydride groups and a polymer containing amine groups.
~ 336735
Such a graft copolymer can be formed if one of the polymers
contains olefinic unsaturation (for example resulting from
polymerisation of a diene) and grafting is carried out
using a free radical peroxide. The polymer containing
unsaturation is conveniently a maleinised diene polymer,
preferably maleinised polybutadiene, containing residual
unsaturation.
The hydroxy- functional component (A) to be reacted
with the amine-containing anhydride-functional component
(B) is preferably a film-forming polymer and can be
selected to give the desired properties in the cured
coating. For example, it can be an addition copolymer
having pendent hydroxy groups such as an acrylic
copolymer containing 5 - 80% by weight, preferably 10-
50% by weight, of a hydroxy-containing ester of an olefini-
cally unsaturated carboxylic acid, for example a
hydroxyalkyl acrylate or methacrylate such as hydroxyethyl
acrylate, hydroxyethyl methacrylate, hydroxypropyl
methacrylate or hydroxypropyl acrylate. The hydroxy-
containing ester can contain further ester linkages orether linkages, for example 2-(beta-hydroxyethoxy)-ethyl
acrylate or methacrylate or an adduct of hydroxyethyl
acrylate or methacrylate with caprolactone. Examples of
olefinically unsaturated monomers which can be copolymer-
ised with the hydroxy-containing ester are acrylic esters
such as butyl acrylate, methyl methacrylate, butyl meth-
acrylate, ethyl acrylate and hexyl acrylate and vinyl
compounds such as styrene, vinyl acetate and vinyl
chloride. The hydroxy component (A) can be a copolymer
containing a polyester segment, for example a graft
copolymer of acrylic monomers onto an unsaturated
polyester. The acrylic monomers are preferably selected
from those mentioned above and include a hydroxy-containing
monomer such as a hydroxyalkyl acrylate or methacrylate.
The polyester segment is preferably a low molecular weight
(below 1000) polyester derived from a polyol such as
ethylene glycol, propylene glycol or trimethylolpropane and
1 33673~
an acid or anhydride such as phthalic anhydride, isoph-
thalic acid or adipic acid with a minor amount of an
unsaturated acid or anhydride such as maleic anhydride.
The polyester can for example form up to 50% by weight,
preferably 5 - 25% by weight, of the graft copolymer.
Coatings prepared using an acrylic hydroxy- functional
component or an acrylic polyester graft copolymer hydroxy-
functional component have excellent gloss, flow and ap-
pearance after spraying.
An alternative method of preparing an addition
copolymer having pendent hydroxy groups for use as the
hydroxy component (A) is to prepare a copolymer having
amide groups, for example acrylamide or methacrylamide
units, and to form N-methylol groups on the amide by
reaction with formaldehyde.
The hydroxy-functional component (A) can alterna-
tively be a telechelic polymer having hydroxy groups at
each end of a polymer chain, such as a polyether, aliphatic
polyester, silicone, diene polymer, hydrogenated diene
polymer, polyurethane, polyisobutylene or polyacrylate.
The use of such a telechelic polymer can give cured coat-
ings having high impact- and abrasion- resistance. Such a
telechelic polymer preferably contains more than two
hydroxy groups per molecule, for example it can be a
polyester or polyether having three or four arms each
terminated by a hydroxy group. One example of such a
hydroxy-terminated polyester sold commercially is a poly-
caprolactone tetraol of molecular weight about 1000.
Alternative hydroxy-functional polyesters can be prepared
from polyols such as ethylene glycol, propylene glycol,
1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,6-
hexanediol, 1,4-cyclohexane-dimethanol, diethylene glycol,
dipropylene glycol or neopentyl glycol with dicarboxylic
components such as phthalic anhydride, isophthalic acid,
maleic anhydride and/or adipic, azelaic or sebacic acid and
a trifunctional compound such as trimethylolpropane, tri-
~, 1 33673S
1 1
methylolethane, glycerol or trimellitic anhydride, using anexcess of the polyols to obtain a hydroxy-tipped polymer.
A lactone such as caprolactone or a hydroxy-acid such as
hydroxy-caproic acid or dimethylol propionic acid can be
included in the polyester-forming reaction. The hydroxy-
functional polyester can be an alkyd polyol containing
fatty acid moieties. Another suitable hydroxy-functional
polyester can be prepared by reacting an epoxide such as
ethylene oxide or a glycidyl ether or ester with a dicar-
boxylic acid. Various hydroxy-tipped polyethers are sold
commercially, for example under the Trade Marks 'Teracol'
and 'Terathane', typically having molecular weights in the
range 600 - 2400. These are generally formed by the
reaction of a polyol such as glycerol, trimethylolpropane
or a higher polyol with propylene oxide and/or ethylene
oxide or with tetrahydrofuran. Hydroxy-tipped addition
polymers, for example hydroxy-tipped polybutadienes or
butadiene/styrene or butadiene/acrylonitrile polymers can
also be used. Hydroxy-tipped polyurethanes can alterna-
tively be used, formed for example from a polyisocyanateand an excess of a polyol component which may comprise a
polyether or polyester polyol and a low molecular weight
pol yol .
Alternative hydroxy-functional polymers suitable for
use as the hydroxy component (A) include amide-containing
polyols prepared by the reaction of a polycarboxylic acid
or anhydride with a polyol and a diamine or amino alcohol,
epoxy polyols prepared by the reaction of glycidyl ethers
of polyphenols such as the diglycidyl ether of bisphenol A
with a bisphenol or an aliphatic diol, polyvinyl alcohol,
an allyl alcohol polymer such as a styrene/allyl alcohol
copolymer optionally containing allyl ether units, cel-
lulose or a cellulose derivative, or a hydroxy-functional
polyurethane.
The hydroxy-functional component (A~ can alternatively
be a non-polymeric polyol or can include a non-polymeric
~, 1 33~3~
12
polyol such as ethylene glycol; 1,4-butane diol, neopentyl
glycol, 1,4-cyclohexane-dimethanol, 2,2-dimethyl-3-hydroxy
propyl 2,2-dimethyl-3-hydroxypropionate, diethylene glycol
or an alkoxylated bisphenol A.
The coating composition of the invention is generally
a two-pack coating in which the hydroxy component(A) and
the polyanhydride (B) are stored separately and are mixed
shortly before use. The coating can be applied to a
substrate by spray, for example conventional airless spray
or twin feed spray in which the polymers (A) and (B) are
not mixed until the spray head, or by roller or brush.
The coating composition generally has a pot life of at
least fifteen minutes when it is to be applied by twin feed
spray or at least one hour after mixing when applied by
other techniques. The coating is preferably an ambient-
temperature-curing coating capable of curing at ambient
temperature, for example 10 - 40C, on the substrate to a
hard film which is tack-free and resistant to solvent so
that it can be overcoated within 24 hours. Maximum hard-
ness, solvent-resistance and impact- resistance generally
develop over a number of days at ambient temperature, for
example 5 - 20 days. Curing can be carried out at tempera-
tures above ambient, for example in the range 40 - 180C,
particularly 100 - 150C, for shorter times if this is
more convenient, for example when coating under factory
conditions.
The proportion of anhydride groups in the anhydride
component (B) to hydroxy groups in the hydroxy component
~A) is preferably 0.5:1 - 2:1.
The anhydride component and the hydroxy component are
each preferably dissolved in a solvent, such as a hydrocar-
bon and/or a polar organic solvent, for example xylene or
toluene or trimethylbenzene or mixtures thereof with an
ester such as butyl acetate or ethoxyethyl acetate or
methoxypropyl acetate or with a ketone such as
13 1 336735
methylisobutylketone or methylisoamylketone. For most
uses the polymers (A) and (B) are preferably compatible
both in solution and in the absence of solvent so that a
clear coating is obtained. For some uses in which tough-
ness of the coating is more important than appearance thepolymers may be less compatible so that there is some
phase separation as the coating dries, leading to domains
of a mixture rich in one polymer in a matrix rich in the
other polymer. This can give increased impact-resistance,
though with less complete cure because the anhydride and
hydroxy components are not stoichiometrically balanced in
each phase.
The coating composition usually contains additives
such as pigments or fillers, for example opaque or trans-
lucent pigments or metallic flake pigments, fillers,plasticisers, antioxidants, UV stabilisers, surfactants or
flow control agents including additives for imparting
thixotropy or sag resistance or pigment orientation.
These additives can be included in either or both of the
components of the paint, although it is preferred to
include any pigments or fillers which may contain sig-
nificant amounts of absorbed water with the hydroxy com-
ponent (A) to avoid reaction with the anhydride.
The coating composition of the invention can be
applied to a wide variety of substrates, particularly to
rigid substrates such as metal, wood, glass or plastics.
The compositions can be applied over most commercially sold
primers. They can be applied by spray, which is generally
preferred, brush or roller or by dipping or flow coating.
The coating compositions of the invention are widely useful
as top coat paints and are particularly useful as automo-
tive paints, including paints for vehicle refinishing.
They can be applied in "clear on base" coating systems in
which a pigmented coat is overcoated with a transparent
clear coat. The coating compositions of the invention can
be used as either the base coat or the clear coat in such
1 336735
14
coating systems or preferably as both. They can also be
applied as clear coats over known base coats such as
polyurethane, acrylic or polyester base coats.
The coating compositions of the invention can alterna-
tively be formed as powder coatings in some cases, providedthat both the hydroxy component (A) and the anhydride
component (B) are solids at temperatures of up to 50C and
provided that at least one of (A) and (B) is a synthetic
resin having a glass transition temperature in the range 0
- 120C, preferably 40 - 90oC. For use in powder coating
the anhydride component (B) preferably does not contain an
olefinically unsaturated double bond in the alpha,beta- or
beta, gamma-position with respect to any anhydride groups,
and if the anhydride component (B) is an addition polymer
the anhydride groups are preferably separated from the
addition polymer chain by at least one intervening carbon
atom. It can be derived from a polyanhydride of this type
described in European Patent Application 209377, for
example by reaction with a primary/tertiary diamine.
The polyanhydrides of the invention can be used as
crosslinking agents for polymers containing hydroxy groups
in uses other than coatings. For example, they can be used
as crosslinking agents for cellulose. The cellulose can
for example be in the form of pulp or in the form of fibres
such as regenerated cellulose or cotton fibres. It can be
reacted with the polyanhydride by heating a slurry of the
cellulosic material in a solution of the polyanhydride in
an organic solvent. Alternatively, wood or a wood product
can be strengthened by impregnation with a solution of the
polyanhydride, or a cellulosic textile material can be
sized with a solution of the polyanhydride.
The invention is illustrated by the following Ex-
amples, in which parts and percentages are by weight.
Examples 1-3, 7, 10, 12, 14 and 17 are examples of the
preparation of amine-functional polyanhydrides according to
~, 1 336735
the invention. Examples 4-6, 8, 9, 11, 13, 15, 16 and 13
are examples of coating compositions according to the
invention.
ExamPle 1
l(a) PreParation of Itaconic AnhYdride CoPolYmer
Butyl acetate solvent (142 9) was placed in a 5-litre
vessel equipped with mechanical stirrer, addition funnel,
reflux condenser and gas inlet. The addition funnel
contained itaconic anhydride (150.0 9), methyl methacrylate
(75.0 9) and styrene (275.0 9). 2,2'-azobismethylbutyro-
nitrile (25.09) was added to the above mixture and the
whole dissolved in butyl acetate (500 9). The solvent in
the reaction vessel was heated to reflux under a nitrogen
atmosphere and the contents of the funnel were added slowly
with stirring over a period of 3 hours. After complete
addition, stirring and heating were maintained for an
additional 1.5 hours to complete polymerisation. The
resulting polymer, POLYMER A, had a number average
molecular weight Mn of 8000 relative to polystyrene, as
determined by gel permeation chromotography, and an an-
hydride equivalent weight of 389.
1(b) Preparation of Amine-Functional PolYanhYdride
Polymer A (92.09) was placed in a 500 ml vessel
equipped with mechanical stirrer, addition funnel, Dean and
Stark tap and gas inlet, and the addition funnel was
charged with N,N-dimethylpropane-1,3-diamine (12.1 9).
The contents of the vessel were heated to reflux under a
nitrogen atmosphere and the contents of the funnel were
added dropwise with stirring over 2 hours, during which
time water of reaction was azeotropically removed. Heating
and stirring were maintained for a further 0.5 hour. In
total, 2.1 9 of water was collected. The resulting
polymer, POLYMER B, had an Mn of 8500 by gel permeation
~_ 1 336735
16
chromatography, an amine equivalent weight of 856 and an
anhydride equivalent weight of 851.
ExamPle 2
2(a) PreParation of Maleic Anhydride CODO1 Ymer
A maleic anhydride copolymer was prepared following
the procedure of Example 1(a) but substituting an equal
weight of maleic anhydride for the itaconic anhydride. The
resulting polymer, POLYMER D, had an Mn of 8200 by gel
permeation chromatography and an anhydride equivalent
weight of 368.
2(b) PreParation of Amine-Functional PolYanhYdride
In an identical manner to that detailed in Example
1(b), Polymer D (75.0 g) in butyl acetate solvent (75.0 9)
was reacted with N,N-dimethylaminopropylamine (10.2 g).
The resulting polymer, POLYMER E, had an Mn of 8700 by gel
permeation chromatography, an amine equivalent weight of
1010 and an anhydride equivalent weight of 979.
ExamDle 3
3(a) PreParation of AnhYdride-Functional PolYmer
Dipentaerythritol (1 mole, 254 g), epsilon-caprolac-
tone (6 moles, 684 g), and dibutyltin dilaurate (1.0 g)
were heated together in xylene (1000 g) at reflux for 4
hours. Mercaptoacetic acid (6 moles, 552 9) was added, and
reflux continued with water trapping until 108 g water had
been collected. Isopropenyl acetate (100 g) was added, and
total reflux was continued for 1 hour to scavenge any
residual hydroxy groups.
Solvent and unreacted ester were removed under vacuum
to leave 1380 g of a fairly mobile pale yellow oil. Maleic
17 l 336735
anhydride (588 g, 6 moles) and triethylamine catalyst
(0.6 g) were added and the mixture was held at below 30OC
with stirring for 4 hours.
3(b) Preparation of Amino-Functional PolYanhYdride
Xylene (1500 9) was added to the above reaction
product, followed by 4-aminopyridine (2 moles, 188 9) over
a 1 hour period. The mixture was raised to reflux and
water (36 g) collected over 7 hours. Volatiles were
removed under vacuum to reveal 2120 9 of polyanhydride,
POLYMER F, as a yellow oil, with an anhydride equivalent of
weight 530.
ExamPles 4 - 6
Pentaerythritol (79.9 g) suspended in xylene solvent
(1400 g) containing dibutyltin dilaurate (0.75 g) was
placed in a 5-litre vessel equipped with mechanical stir-
rer, reflux condenser, addition funnel and gas inlet, and
the addition funnel was charged with dry epsilon-caprolac-
tone (665.7 g). The vessel contents were stirred at reflux
under a nitrogen atmosphere and the contents of the addi-
tion funnel were added to them slowly over 1 hour. Heatingand stirring were maintained for a further 2 hours and the
solvents were removed under vacuum. The resulting
polymeric tetraol, POLYMER C, had an Mn of 1272 and a
hydroxyl equivalent weight of 318.
Exam~le 4
Polymer B (Example 1) (2.67 parts) in butyl acetate
solvent (4.01 parts) was mixed with Polymer C (1.00 part)
in butyl acetate (1.00 part) and cast on glass. It was
cured at ambient temperature to give a hard, tough, glossy
film within 16 hours. After 7 days at room temperature the
film had good resistance to methylethylketone (MEK).
~ 1 336735
18
ExamDle 5
A mixture of Polymer E (Example 2) (3.08 parts) in
butyl acetate solvent (4.62 parts) and polymer C (1.00
part) in butyl acetate solvent (1.00 part) was cast on
glass and cured at ambient temperature. After 7 days at
room temperature the film had good MEK resistance.
ExamDle 6
Polymer F (Example 3) (5.30 parts) was mixed with
Polymer C (3.18 parts) in butyl acetate solution and cast
on glass. The coating cured at ambient temperature to a
hard but highly flexible coating.
ComDarative ExamDle
A copolymer of itaconic anhydride was prepared in the
same way as Example 1(a) but with a monomer composition
itaconic anhydride 13%, methyl methacrylate 20% and styrene
67%. The polymer obtained had approximately the same
anhydride equivalent weight as Polymer B.
It was admixed with hydroxy-functional Polymer C and
coated on a glass panel as in Example 4. After 7 days at
room temperature the coating was soft and dissolved by
brief contact with solvents such as xylene or MEK.
ExamDle 7
PreDaration of anhYdride DolYmer
Itaconic anhydride (300g), styrene ~5709), methyl
methacrylate (1309), "Vazo 67" (Trade Mark) free radical
initiator (509) and a solvent mixture of xylene (3009) and
N-methyl pyrrolidone (1009) were premixed and run into a
refluxing mixture of xylene (4509) and N-methyl pyrrolidone
19 1 336735
(1509) over four hours. The mixture was held at reflux for
a further one hour and cooled to provide a polyanhydride
solution having a solids content of 46.6%, an Mn of 3,800
and a weight average molecular weight (Mw) of 7700 (rela-
tive to polystyrene).
PreParation of amine-functional PolYanhYdride
N,N-dimethyl propane-1,3-diamine (9.29, equivalent to
a third of the available anhydride groups) was added
dropwise over 15 minutes to the refluxing anhydride polymer
solution (2159) in a vessel fitted with a water separator.
Reflux distillation was continued for a further seven
hours, when 1.7g of water had been collected. The product
had a solids content of 50.0% and an anhydride equivalent
weight of 1204.
ExamPle 8
PreParation of acrYlic PolYol
Hydroxyethyl acrylate (193.59), methyl methacrylate
(403.59), styrene (403,59) and "Vazo 67" initiator (409)
were premixed and added dropwise to refluxing butyl acetate
(10009) over 3 hours. Reflux was continued for one hour to
yield a polymer solution having a solids content of 50%, an
Mn of 5200, an Mw of 10300 (relative to polystyrene) and a
hydroxyl equivalent weight of 600.
Coatinq comPosition
24.19 of the amine-functional polyanhydride solution
of Example 7 and 12.0 9 of the acrylic polyol solution
prepared above were mixed and cast as a film on glass at a
dry film thickness of 60 microns. The coating was cured by
heating at 150C for 3 minutes. The solvent-resistance of
the cured coating was tested by rubbing with a cloth soaked
in methylethylketone (MEK); the coating was substantially
l 33673~
unaffected by 200 MEK double rubs.
Example 9
PreParation of PolYester polYol
Trimethylolpropane (1 mole, 134 9), caprolactone (6
moles, 6849) and xylene (4079) were heated at reflux in the
presence of tetrabutyltitanate (0.49) for four hours. The
xylene was then removed by vacuum distillation to provide a
polymer having a solids content of 97%, an Mn of 814 and a
hydroxyl equivalent weight of 271.
Coatin~ comPosition
24.1 9 of the amine-functional polyanhydride solution
of Example 7 and 2.8 9 of the polyester polyol prepared
above were mixed, cast as a film and heat-cured as
described in Example 8. The solvent-resistance of the
cured coating was 150 MEK double rubs.
ExamPle 10
PreParation of PolYmeric anhYdride
Aconitic acid (2239), styrene (8009) and "Vazo 67"
(509) were dissolved in tetrahydrofuran (7809) and added
dropwise to refluxing butyl acetate over three hours.
Azeotropic reflux was continued for a further eight hours,
removing tetrahydrofuran and water through a packed column,
whilst replenishing butyl acetate as necessary to avoid
development of high viscosity.
The product was a polymer having a solids content of
50%, an Mn of 3400 and an Mw of 8500 (relative to
polystyrene). It showed strong anhydride peaks in its
infrared spectrum and its acid value after precipitation
and methanolysis was determined as 43.6, indicating sub-
21 1 336735
stantial incorporation of aconitic residues.
Its calculated anhydride equivalent weight was 780.
PreParation of amine-functional PolYanhYdride
Dimethylethanolamine (11.49) was added dropwise to the
refluxing polymeric anhydride solution prepared above
(2009) over 15 minutes. Azeotropic reflux was continued
until 2.3mls of water had been removed and no hydroxyl
signal was visible in the infrared spectrum ~8 hours). The
resulting polymer had a solids content of 73%. Its amine
equivalent weight after precipitation was determined as
783, and its anhydride equivalent weight was 851.
Example 11
11.7 9 of the amine-functional polyanhydride solution
of Example 10 and 2.8 9 of the polyester polyol of Example
9 were mixed and cast as a film on glass at a dry film
thickness of 60 microns. The coating film was allowed to
cure at ambient temperature (about 20C). The solvent-
resistance of the coating was tested after 7 days and was
found to be 95 ME~ double rubs.
ExamPle 12
Preparation of amine-functional PolYanhYdride
Diethylaminoethyl methacrylate (1009), styrene (6309),
neopentylglycol dimethacrylate (709), and "Vazo 67" ~50g~
were dissolved in xylene (4009) and used as feed 1.
Itaconic acid (2329) was dissolved in tetrahydrofuran
(10009) as feed 2.
Feeds 1 and 2 were separately added dropwise to
22 l 336735
refluxing xylene (4669) and N-methylpyrrolidone (2009) over
three hours whilst simultaneously removed tetrahydrofuran
by distillation through a packed column. A~eotropic
distillation was continued for a further eight hours,
replenishing the solvent mixture with butyl acetate as
necessary, until the infrared spectrum showed strong
anhydride bands and very weak signals due to free car-
boxylic acid.
The resulting polymer solution was adjusted to 50%
solids content. The polymer had an amine equivalent weight
of 1850 and an anhydride equivalent weight of 560.
ExamPle 13
11.2 9 of the amine-functional polyanhydride solution
of Example 12 and 2.89 of the polyester polyol of Example
9 were mixed, cast as a film and allowed to cure at ambient
temperature as described in Example 11. The solvent-
resistance of the coating after 7 days was 100 MEK double
rubs.
ExamPle 14
Preparation of Polymeric anhYdride
A proprietary maleinised, anhydride-functional poly-
butadiene of calculated anhydride equivalent weight 490
(available from Revertex as "Lithene PM25MA ) (2009),
xylene (4009) and palladium metal (0.49) were treated with
hydrogen at a pressure of 80 atmospheres and a temPerature
of 100C for 12 hours in a rocking autoclave. The vessel
was cooled, vented and discharged to provide a solution,
after recovery of the palladium by filtration, having a
solids content of 33%, an anhydride equivalent weight of
490 and substantially no unsaturation.
PreParation of amine-functional polyanhYdride
23 l 336735
N,N-dimethylpropane-1,3-diamine (1.379, equivalent to
10% of the available anhydride) was added dropwise over 15
minutes to the hydrogenated polyanhydride solution prepared
above (2009). The mixture was azeotroped for eight hours
and a proportion of the solvent removed by vacuum distilla-
tion to provide a polymer having a solids content of 50%,
an amine equivalent weight of 5000 and an anhydride e-
quivalent weight of 555.
Example 15
PreParation of acrylic polYol
Hydroxyethyl methacrylate (130.09), methyl methacry-
late (4359), styrene (4359) and Vazo 67" (509) were
premixed and added dropwise to refluxing butyl acetate
(10009) over three hours. Reflux was continued for one
hour to yield a polymer solution having a solids content of
54%, an Mn of 4800, an Mw of 9000 (relative to polystyrene)
and a hydroxyl equivalent weight of 1000.
11.19 of the amine-functional polyanhydride solution
of Example 14 and 18.59 of the acrylic polyol solution
prepared above were mixed, cast as a film and heat-cured as
described in Example 8. The solvent-resistance of the
cured coating was greater than 200 MEK double rubs.
Example 16
ll.lg of the amine-functional polyanhydride solution
of Example 14 and 12.09 of the acrylic polyol solution of
Example 8 were mixed, cast as a film and heat-cured as
described in Example 8. The solvent-resistance of the
cured coating was greater than 200 MEK double rubs.
ExamPle 17
1 336735
24
PreParation of amine-functional PolYanhYdride
Ethyl acrylate (47.19), diethylaminoethyl methacrylate
(52 99) and "Vazo 67" (5.09) were mixed and fed into
refluxing butyl acetate (lOOg) over three hours. The
resulting polymer had an amine equivalent weight of 349.
Lithene PM 25 MA (125.99) was then added, and benzoyl
peroxide (11.39) added portionwise over 4 hours. The
mixture was held at reflux for a further 4 hours to form a
graft copolymer, cooled and discharged. It had a solids
content of 70%, an amine equivalent weight of 789 and an
anhydride equivalent weight of 879. Whilst grafting was
probably not complete, it was sufficient to ensure
compatibility.
ExamPle 18
The grafted polymer of Example 17 (12.69) was mixed
with the acrylic polyol solution of Example 15 (18.59) and
cast onto steel panels. Heat-curing (20 mins at 150~C)
produced a hard film, resistant to 70 ME~ double rubs.
Such a coating can be used as a stoving primer.
