Note: Descriptions are shown in the official language in which they were submitted.
~ 0~89
PA~ 37936
ENVT~I LAI.LY FRIE~DLY AIJTOXIDISABLE ALKYD
COATING COMPOSITIOI~
This invention relates to environmentally friendly
autn~ h1 e film-forming alkyd coating compositions such
10 as paint, varnish or woodstain and especially to coating
compositions suitable for application by brush at ambient
temperatures (e.g. 18Cj to architectural surfaces such as
those found on buildings or their fittings or furnishings.
It also relates to autoxidisable film-forming material for
7 5 use in the coating compositions .
"Autn~ l; 7~hle" is sometimes referred to as "drying"
or "air drying". All three terms mean that when a coating
of the autn~ hle film-forming material is applied to a
20 surface~ and ~exposed to air in the presence of an
al~tn~ t;nn catalyst (such as cobait octoate or
naphthenate), the alkyd polymer will crosslink or ~dry" to
f orm a macromelecular f ilm by oxidation involving the
olefinic unsaturation which is found in alkyd polymers.
25 The macromelecular film serves to protect the surface and
to bind together any non-film-forming cl nnl~ntS of the
coating composition such as pigments and extenders. It is
therefore sometimes called a protective binder material.
3~) AIkyd polymers~ are amongst the oldest protective
binder materials used in paints. The alkyd polymers
generally used in coating compositions for architectural
surfaces usually c~mprise high molecular weight
dicarboxylate polymer chains having an approximately
35 uniform distribution of molecular weights as illustrated in
Figure-1 of t~e drawings. The molecular weights usually
~ 2~0S89
extend over a range of about 200 (or more usually 300) to
200, 000 with typically about 20 to 25wt~ of the polymer
chains having molecular weights in the range of 1,500 to
3, 500, about 50 to 60wt~ having molecular weights ln the
5 range 3,500 to lO0,000 and about 25 to 35wt~ having
molecular weights in the range 5,000 to 100,000. About 2
to 15wt~ of the chains have molecular weights above 100,000
and although this i~ a small proportion, it has been
discovered that these high molecular weight chains assist
10 alkyd paints to dry quickly at ambient temperatures. This
is particularly important if coatings applied in a
th~ rkn,~g of from 100 to 20011m are to be able to dry
without wrinkling. l~m is 10-~n. The ratio Mz/Mw for a
typical alkyd polymer is of ten about 2 . 7 to 3 . 0 where Mz
15 represents Z average molecular weight and Mw represents
weight average molecular weight. A full definition of Mz
is given on pages 127 to 129 of the second edition of the
book "Pri~ciples of Polymer systems" by F Rodriguez and
~llhl 1 ~h~ 1983 by McGraw-Hill Tnt~rn~ti ~m~l of IJondon.
20 Pages 127 to 129 are herein incorporated by reference. A
technique for measuring molecular weights is given later in
this specif ication .
Conventional alkyd polymers for use in paints suitable
25 for application at ambient temperatures are dicarboxylates
made by esterifying an aromatic dicarboxylic acid or its
anhydride with a substituted polyol which is an alcohol or
ether alcohol originally ~f1nt~;n;n~ at least three
alcoholic hydroxyl groups of which usually two remain
30 unsubstituted and therefore free to esterify pairs of
dicarboxylic acid or ~nhydride molecules whilst most of the
r,om~in~lPr are substituted by an autoxidisable
hydrocarbylcarbonyloxy moiety, i . e .
G~ eno\D89\5pcc.1~/1~194
~ 2140~8~
R - C - 0-- or RC02--
where R is a partially olefinically unsaturated hydrocarbon
5 chain such as is found in l;n~-lPn;~ acid. ~lt~;fl~hle
hydrocarbylcarbonyloxy moieties are often called "oils" in
the paint industry. Alkyl polymers cnnt~;n;n~ large
proportions (eg. over 60wt96) of the moieties are called
"long oil" alkyds whereas those ~n~;n;ng lesa than 45wt96
10 are "short oil" alkyds and those beween are "medium oil"
alkyds .
~ sterification involves heating together the reactants
and in the past, the esterification was often performed
15 using fused rP;~--tAnt~ Unfortunately, fusion causes
;m-t;~n of reactants some of which are toxic and
~llhl ;m~t;on may algo give rise to partial blockages in
industrial systems as a result of ~llhl ;mPfl material re-
solidifying. Therefore, nowadays industrial
20 esterifications are preferably performed by heating the
reactants in azeotropic solvents when making alkyd polymers
for architectural paints. A solution process is also
easier to control and the use of solvents which are
azeotropic facilitates the removal of the water produced in
25 the esterification reaction.
Typical dicarboxylic acid rP~t-t;;nt~ include
isophthalic, succinic, adipic and sebacic acids whilst
phthalic anhydride is typical of the anhydrides. Typical
30 alcoholic polyols include alcohols and ether alcohols such
as trimethylol propane, glycerol, sorbitol, mannitol,
glucose, pentaerythritol, di- and tripentaerythritol and
di - trimethylolpropane . Typical autoxidisable
hydrocarbylcarbonyloxy moieties include those derivable
35 from aut~ hl e natural oils such as linseed,
cottonseed, corn, rapeseed, soya bean, tung and tall oils.
G:\c~ew\r789;5peo.13/12/94
2140~83
.
The groups will contain between 12 and 30 (usually 16 or
18) carbon atoms some of which will be linked by olefinic
double bonds. Whilst the products obtained from a
conventional process f or making alkyd polymer are too
5 complex to merit a simple chemical formula, it is probable
that an alkyd dicarboxylate polymer made using isophthalic
acid and a substituted pentaerythritol would contain a
prc~fl~ ' n~nt proportion of units as represented below
co~ R co~R
~ Cl~?--~ C~7;! ~ c oz ~ c;~+
~ C~LR ~ c~R
with the possibility of chain hr~nrh;n~ if more than two of
the alcoholic hydroxy groups have remained unsubstituted
15 which can occur to some extent.
In the above f ormula + represe~ts
,CH2--
-- CH~ -- C-- CH2
CH2--
25 and RCO2- represents a hydrocarbylcarbonyloxy moiety made
rx; ~ hl e by the presence of olef inic
unsaturation in the hydrocarbyl part of the
moiety .
Esterification is usually performed until the acid value of
the alkyd ester has fallen ~:o below 16mgROH/g of the ester.
A typical alkyd polymer suitable for use in architectural
paints can therefore in principle be described as a high
35 molecular weight polymeric aromatic dicarboxylic ester of
low acid value (eg. below 16 mgROH/g of the ester)
G~ t~oU7b9~5pcs.13/12/94
2140~89
cnntAining mainly divalent esterifying groups which are
substituted polyols Hubstituted by at least one
aut~ ;q~hle hydrocarbylcarbonyloxy or "oil" moiety. It
has been discovered that the alkyd polymer must have an
5 approximately uniform distribution of molecular weights
including a small, but significant proportion of molecular
weights above 100, 000 in order that the paint may dry
quickly .
Conv~nt; ~n~ alkyd polymers have the advantage of
being largely derivable from agricultural products which
can be made from renewable sources. They are also easily
biodegraded when buried in landfill sites which is
advantageous when large quantities of waste paint need to
15 be discarded. However alkyd polymers (at least when made
by esterifications performed in solution) have the
intrinsic problem of being extremely viscous liquids owing
to the large proportion of polymer chains having molecular
weights in the range 3500 to 100, 000 and especially in the
20 range 5000 to 100, 000 . For example, attempts to measure
accurately the viscosity at 25C of a 99wt% solution of a
typical alkyd resin in xylene using the bubble tube
technique fail, because the viscosity of the solution is
found to be well over 300 stokes (ie. 300xlO4m~/s)
25 Therefore in nearly all cases it has been necessary to
dissolve the alkyd polymer in large amounts of volatile
organic solvent to obtain a paint having a viscosity of
about 2 to 10 poise (ie. 0.2 to 1 Pa.sec) and preferably 5
poise so that it can be applied by brush at ambient
3 0 temperature~ to produce thick coatings which may be up to
200~m thick. Traditional liquid alkyd paints contain as
much as 30wt96 or more of volatile organic solvent which is
usually a hydrocar~on liquid such as white spirit.
Volatile organic solvents have a boiling point of up to
35 250C at 1 bar and so, as the paint dries, the solvent
- evaporates creating envir~-nm~nt~l pollution and also
G~ S=J\I789~3PeC~I3~ 94
~ 21~0~9
localised unplea~3ant smells. In 1980, a new standard (RAII-
UZ-12a or "~31auer Engel") for low polluting paints was
introduced. The new standard calls for paints to contain
at least 85wt96 non-volatile material (sometimes called
5 "solids" for brevity) which in effect means that the paints
must contain less than 15wt96 volatile organic solvent.
This high viscosity problem is a particular n~ nt-
~in so-called ~non-drip'~ paints. Alkyd "non-drip" paints
10 have a thixotropic gel structure which may be imparted, for
example, by reacting a polyamide with the alkyd resin at
eleYated temperatures as described in United States Patent
Specification US 2 663 649 pllhl 1 F~h~rl in 1953 or Deutsche
Auslegeschrift DE 1 198 556 pllhl; l~lhf~fl in 1965 . An alkyd
15 "non-drip" paint will generally have a gel strength of at
least 150 g. cm as measured by the technique described
later. When the paint is brushed onto a surface, the gel
is temporarily broken down by the shear f orces imparted by
the brush and the paint is temporarily converted to a
20 viscous liquid. However, the intrinsic viscosity of the
polyamide-modif ied alkyd polymers used in thixotropic gels
is even greater than that of conventional alkyd polymers
and 80 even more volatile organic solvent has to be present
to ensure that alkyd "non-drip" paints can be applied by
25 brush. Accordingly, traditional "non-drip" alkyd paints
contain over 40wt~6 of the solvent Moreover, many
thixotropic alkyd polymerg 801d for u8e in fnrril;~t'n~
~non-drip" paints are 80 intrinsically viscous that they
have to be supplied as solutions ~nnt~n~ng as much as
30 50wt~6 of the volatile organic solvent in order to allow
them to be f, 1 ~t~-l into "non-drip" paints
Simple attempts to reduce the amount of solvent used
in an alkyd paint would, of course, re-introduce the high
35 viscosity problem mentioned above which would make the
paint dif f icult to apply by brush . Theref ore much
r ~ `7a9\Cr~ 2l94
~ 21~05~3
attention has been dire~ted to the replacement of at least
some of the volatile organic solvent by relatively
involatile reactive autn~ R~hl e liquids which are
sometimes known as "reactive diluents". The reactive
5 diluents dilute the viscous alkyd polymer sufficiently to
enable it to be brushed onto a surface yet they are not
lost as pollutants into the atmosphere by evaporation from
the drying coating. Instead, once the paint has been
applied to the surface, the reactive diluents ~lltn~; rl; ~e
10 along side the alkyd polymer and they crosslink (probably
with the polymer) so beeoming part of the macromolecular
film. Therefore the reactive diluent no longer exists as
a liquid which would either slowly evaporate causing
pollution or would remain in the coating and theref ore
15 detract from the hardness of the film An early example of
this approach is provided by United States Patent
Specification US 4 311 ~24 (publi8hed in 1982) which
discloses alkyd paints cnnti~;n;ng an involatile reactive
diluent which is a dicyclopentenyloxyalkyl ester of an
20 autn~ ; R~hl e ethylenically unsaturated carboxylic acid
such as acrylic or methacrylic acid, l.e.
C~1~=C~C~7~(
Unfortunately, thick coatings of such paints were found to
dry (i . e. autoxidise) too slowly .
Faster drying alkyd paints are provided by European
35 Patent Specification EP 0 253 474A (published in 19~)
which discloses alkyd paints c~mt~;n1n~ a reactive diluent
C., ' , 1~112/94
2140~8~
which comprises a polysubstituted alkane rnnt~ininrJ at
least one autoxidisable hydrocarbylcarbonyloxy moiety and
also at least one relatively quickly autnx;~ hle allyloxy
moiety and wherein the total number of autnx; tl1 q~hl e
5 moieties i9 at least three, for example
O - CH~ - CH = CX~
RCO2 - C~ - CH - CX~ - O - C~2 - CH = CH7
More sper1f;r~11y, the reactive diluents are
hydrocarbylcarbonyloxy and allyloxy derivatives of
10 PO1Y~IYdL~Y alcohols such as trimethylol propane, glycerol
and pentareythritol. The reactive diluent shown above and
illustrated by Bxample 1 of EP O 253 474A is a substituted
trimethylol propane rnnt~;n;ng one ;~lltn~;~iRilhle
hydrocarbylcarbonyloxy moiety and two autrx~ hl e
15 allyloxy moieties. The presence of the allyloxy moieties
confers a good lnitial rate of autnx;rl~t;nn on alkyd paints
rnnti~;n;ng the reactive diluent, but the later stages which
confer hardness o~ the film are unsatisfactory and in
particular the scratch resistance (i.e. hardness) of the
2 0 f ilm is poor .
European Patent Specification EP O 357 128A (published
in 1990) discloses that the hardness of autoxidised films
obtained from alkyd paints cnnt~;n;ng allyloxy reactive
25 diluents can be improved by using the reactive diluent in
rrmhin~t;on with an autnx;r~ hll~ reactive oligomer. The
reactive oligomer comprises a polycarboxylic ester (more
particularly trimellitic ester) rnnt~;n;ng three highly
autnx; ~ hl e ester moieties which are polysubstituted
30 etheralkyl moieties (more particularly dipentaerythrityl
groups) each in turn substituted by five Alltrx;~ hl e
hydrocarbylcarbonyloxy moieties of the type found in
conventional alkyd polymers. An oligomer of this type
derived from trimellitic anhydride and substituted
35 dipentaerythritol is also too complex to merit a simple
chemical formula, but it is probable that the prc~ n~nt
(3:~c~e~o\D89\Spec.1311~/94
~ 21~0~8~
species can be indicated by the following formula:
ciR C~LR Cdl~ c~
~CO~ ~CC~ ~ CO~,--O+~
~o~R co~ cc2~,~
~COL-- OtC2,~
co~,lt Co,,lt
10 where ~ O + represents
C~H2-- CH2 --
--CX2 - C - CH20 - CH2 - C - CH~--
CH2 - \C~2 -
The aut~ Ahle reactive oligomer improves film
hardness but its presence in combination with the more
rapidly autoxidisable allyloxy reactive diluent complicates
the formulation o~ coating compositions and is a classic
source of toxic bi-products.
World Patent Application WO88/03153 (pl1hl; f~hl~l in
1988) discloses an alternative approach to reducing the
amount of solvent needed in alkyd paints intended for
architectural uses. WO88/03153 dlscloses a single step
25 esterif ication of di- or polycarboxylic acids or their
anhydrides in the presence o~ conventional autt~ hl e
hydrocarbylcarboxylic acids (ie fatty acids with
aut~ Ahle long chains) . By choosing polyols comprising
at least 80wt~ of dipentaerythritol or
30 ditrimethylolpropane, WO88/03153 was able to achieve
relatively high molecular weight film-forming materials
which nevertheless had low viscosities and could therefore
be used in paints c~-ntA;n;ng as little as 15wt~ organic
solvent. ~owever, WO88/03153 does not specify the
35 molecular weight distribution present in its film-forming
materials and in particular materials capable of giving
G:\c~e~o\1789\5pcc. 13112194
~ 2~ ~0~9
10,
85wt~6 solids in paints were found to be de~icient in
polymer chains having molecular weights above 100,000.
Therefore thick coatings of paints made using the materials
were f ound to dry 910wly at ambient temperatures as
5 compared with conventional alkyd paints. In addition, at
least 80wt96 of the polyol must be either dipentaerythritol
or ditrimethylol propane even though ether alcohols such
as dipentaerythtritol are expensive reactants.
An object of this invention is to provide an easily
f ormulated envi~, A 1 1 y f riendly autn~; ~ hnl e alkyd
coating composition which is capable of rnntzlinln~ at least
85wt96 of non-volatile material, (ie. not more than 15wt~
volatile organic solvent) comprising film-forming material
15 able to be made by an industrial esterification performed
in solution and optionally non-film-forming material such
as pigment or ~tPnfl~r and which has a viscosity suitable
for application by brush to architectural surfaces at
ambient temperature (e.g. 18C) and which when applied in
20 coatings up to 200,um thick dries riuickly without wrinkling
to give a hard, non-sticky, scratch-resistant protective
binder film similar to those obtained from more
conventional alkyd coating compositions . Obj ects of
modif ications of the invention are to promote the use of
25 cheaper polyols such as pentaerythritol.
Accordingly, this invention provides an
envir, ~lly friendly autn~ hle alkyd coating
composition rnnt~;nlng autn~;A~tion catalyst and film-
30 forming material rnnt~;nln~ autoxidisable alkyd polymermoieties and in which at least a portion of the f ilm-
forming material has been chemically co-reacted with
polyamide or with a polyamine/polyisocyanate combination to
produce a co - reaction product wherein
.
G:\ccs=~o\178~5pec.l3/12/94
~ 214~89
11
(a) ~efore the co-reaction, the film forming material
has a Z average molecular weight (as det or~n; n~r9 using
gel permeation chromatography) of at least 30,000, a
viscosity of less than 34 ~preferably less than 27)
stokes (ie lO~m2/s) when measured at 25C as a 99wt7s
solution in xylene at 25C and a non-uniform
distribution of molecular weights (as det~ n~l by
gel p, -~t;f~n chromatography) which has a peak in the
range 1,500 to 3,500 and where at least 25wt96 of the
film-forming material has a molecular weight in the
range 1,500 to 3,500 and
(b) moieties derived from the co-reacted polyamide or
polyamine/polyisocyanate c~mh;n;3tlr~n amount to 2 (and
preferably 3) to 15wt~ of the portion which has been
co - reacted.
A typical molecular weight distribution for the film-
forming material is illustrated by ~igures 2, 2A, 3 and 4.
The molecular weight distributions may be determined by gel
permeation chromatography using the technique described in
more detail later in this Specification. Viscosity can be
conveniently measured using a bubble tube technique
The selected distribution of molecular weights (before
co-reaction) rl I;n.~r~ with the moieties derived from the
co-reaction with polyamide or the polyamine/polyisocyanate
combination produces a bio-degradable film-forming material
obtainable largely from renewable resources which can be
used to formulate coating compositions which may contain as
much as 85wt9~ solids or conversely as little as 15wt9~
volatile organic solvent, yet which can be brushed onto a
surface at 18C to produce sag-resistant coatings of a
thickness of up to at least 2001Lm which can dry quickly
without wrinkling to give a dry, non-sticky, hard, scratch-
resistant protective binder film. In addition (for
r~ ~7Q9\~r~ 7/94
12
countries where more than 15wt96 of volatile organic solvent
can be tolerated), it is possible to produce useful
thixotropic alkyd paints cr~nt~;n;ng less than 30wt90 of the
solvent and in particular it is possible to produce "non-
5 drip" alkyd paints having a gel strength of at least 100g.cm and r~ntA;n;ng as little as 15 to 20wt96 volatile
organic ~olvent.
It is preferred that (before any co-reaction) at least
10 26wt~ (and most preferably 30wt~) of the film-forming
material should have a molecular weight lying in the range
1,500 to 3,500 and that the peak molecular weight should
lie in the range 1,800 to 2,500. It is further preferred
that at least 2 (and most preferably 4 to 15) wt~ of the
15 film-forming material should have a molecular weight of
above 100,000 and/or less than 48 ~most preferably less
than 35)wt~ should have a molecular weight in the range
10,000 to 100,000. It is also preferred that the Mz of the
film-forming material should be above 50,000 and most
20 preferably above 70,000. The molecular weight distribution
may be bi- or polymodal having one or more smaller peaks
inside and/or outside the 1,500 to 3,500 range. Preferably
the ratio Mz/Mw should exceed 2.8, more preferably 3 and
where reasonably possible it is preferred that it should
25 exceed 5.
A convenient way to obtain a film-forming composition
having the required molecular weight distribution according
to this invention is to perform a two step esterification
30 in which a precursor mixture of esters is made (preferably
using a solvent process as opposed to a fusion process) in
the first step and then in a subsequent step, the precursor
esters are reacted (again preferably in solution) with a
polycarboxylic acid or anhydride rrnt~;n;ng at least three
35 carboxylic acid groups or their anhydride to make the film-
forming material. The two step process may be either a
G \c~o\1789\5pec 13/l~94
~ 214058~
"simple" two step esterification process or a "split" two
step esterification process. In the simple process, the
first step comprlses making the precursor mixture of esters
by reacting together (for example by heating under reflux
5 at 180 to 250C) a mixture of the following reactants:
a) an aromatic dicarboxylic acid or its anhydride
(for example isophthalic acid or phthalic anhydride),
b) a polyol ~nnt~;n;n~ at least five ~preferably
six) hydroxyl groups (for example dipentaerythritol)
optionally together with a polyol cnnt:l;n;n~ 3 or 4
hydroxyl groups (for example pentaerythritol) and
c) an autoxidisable hydrocarbyl carboxylic acid
~nnt~;n;ng 12 to 30 carbon atoms (for example the
fatty acids derived from the various natural oils
known for use in making alkyd paints).
20 The mixture preferably rnnti~;nF~ the following molecular
percentages of the reactants, namely
a) dicarboxylic acid/anhydride 3 to 10 mol~
b) polyol ~nnt=~;n;
at least f ive hydroxyls 5 to 15 mol~
polyol alcohol ~nnt;3;n~n~
three or four hydroxyls 0 to 20 mol96
and c) ~ tn~; .1; ~hle hydrocarbyl
carboxylic acid 60 to 85 moll
21~0~9
14
The precur~or mixture of esters contains:
1. ~ong oil (pre~erably at least 7~wt9~ oil ) alkyd
polymers which have a low molecular weight (for example
5 polymers having an Mz of from 3,000 to 10,000) and a high
hydroxyl value of at least 40. The alkyd polymers contain
derivatives of polyols in which preferably only two of the
hydroxyls of each polyol have formed ester links to
dicarboxylic acid creating diester polymer chains and
10 preferably 80 to 95~6 of the Ll ;n;ng hydroxyls of the
polyol have formed ester links with the autr~;fl;q~hle
hydrocarbylcarboxylic acid thereby imparting
autn~ h; l ity to the polymer chains. The r, ;n;n~
unreacted 5 to 2096 of hydroxyls impart a high residual
15 hydroxyl value to the alkyd polymer. Again, the alkyd
polymer is too complex to merit a simple chemical formula,
but the formula indicated in Figure 5 is illustrative of
the type of structures which can be expected.
20 2. ~ong-oil esters in which some (and preferably all but
one or two) of the hydroxyls of each polyol c~nt~;n;ng at
least five hydroxyls have ~ormed ester links with the
autr~ hl e hydrocarbyl carboxylic acid. A typical
f ormula would be:
co~R c~
Ho ~ o Jrco~
C~R cv
3. Optionally non-polymeric long-oil esters of a polyol
~ nt;3;n;nr; three or four hydroxyl groups in which all but
one or two of the hydroxyl groups have formed ester links
35 with the autnsr; rl; c~hl e hydrocarbyl carboxylic acid. A
typical formula would be:
.
r~ 9\~ 2/94
~ 21~058~
~0~,~
Ho ¦ co, R
C~
The second step of the simple two step esterification
comprises reacting the precursor mixture of esters with the
polycarboxylic acid or anhydride. The esters and
acid/anhydride are mixed together (pref erably as solutions
in organic solvent) and are subjected to for example 180 to
250C to make the film-formi~g material by esterifying the
acid/anhydride with the residual hydroxyl8 prese~t in the
precursor mixture of esters. The amount of polycarboxylic
acid or anhydride used should pref erably be chosen to
ensure very nearly full esterification of the
polycarboxylic acid or anhydride and should preferably be
sufficient to esterify from 80 to 99% of the theoretical
residual hydroxyl present in the precursor mixture of
esters. This in practice means that from 2 to 8 mol~ and
preferably less than 4.5wt96 (based on total amount of
reactants used in the first step) of polycarboxylic acid
should be used. The residual hydroxyls in the precursor
mixture of esters occur in both the low molecular weight
alkyd polymers and in the long - oil esters derived f rom the
polyols. Therefore the film-forming materia~ contains
polycarboxylic esters in which the esterifying moieties
include moieties derived from the long oil alkyd polymer
and also moieties derived from the long oil esters of the
polyols. The film-forming material will also contain
residual amounts of the esters of the precursor mixture
which have not reacted with the polycarboxylic acid or
anhydride. In particular the second mixture will contain
residual amounts of the autoxidisable long oil ester of the
polyol con~in~n~ at least five hydroxyls.
G:\c~eao\1789\5pcc.13112/94
16
Accordingly, the second step o:~ the simple two step
esterif ication provides a f ilm- f orming material according
to this invention cont~;n;ng autoxidisable alkyd polymer
moieties in which the film-forming material includes esters
5 of a polycarboxylic acid which rnnt~in~ at least three
carboxylic acid groups and/or esters of an anhydride of
such a polycarboxylic acid wherein the esterifying moieties
are chosen f rom
a) alkyd polymer moieties,
b) moieties derived from a substituted
polyol rrnt;l;n;ng at least five hydroxyls prior
to substitution up to all but one of which
hydroxyls per polyol molecule have been
s u b s t i t u t e d b y a u t o x i d i s a b l e
hydrocarbylcarbonyloxy moieties and optionally
c) moieties derived from a substituted polyol
cr,ntA;n;ng three or four hydroxyls prior to
substitution up to all but one of which have been
substituted by autoxidisable
hydrocarbylcarbonyloxy moieties.
Typical formulae for representative polycarboxylic esters
25 are illustrated diagrammatically in Figure 6 of the
drawings .
Preferably from 20 to 60 molar~ of the esterifying
moieties in the polycarboxylic esters are alkyd polymer
30 moieties and 20 to 70 molar~ (most preferably 30 to 60%)
are moieties derived from the substituted polyol originally
crnt~;n~n~ at least five hydroxyls. Often the esters will
also contain up to 20 molar96 of moieties derived from the
substituted polyol origiually c~nt~;n;ng three or four
3 5 hydroxyl s .
n ~ 9\~ r ~ 19~
I . . 2140~89
17
Preferably the coating compo~litions according to thi~
inve~tion should contain up to about 10 wt9o of residual
hle ester of the polyol cnntil;n;n~ originally at
least five hydroxyl groups which residual ester has not
5 reacted with the polycarboxylic acid or anhydride. The
coating compositions generally also contain up to 10 wt~ of
residual aut~nr~ 3hle ester of the polyol cnntil;n;ng
originally three or ~our hydroxyl groups and which too has
not reacted with the polycarboxylic acid or anhydride.
The polycarboxylic acids or anhydrides used in the
second step preferably contain only three or four
carboxylic groups and most preferably three. Ty-pical of
these are the tricarboxylic and tetracarboxylic acids or
15 their anhydrides such as trimellitic anhydride or
pyromellitic anhydride as shown below:
~0 O~ ~0
C7
30 trimellitic anhydride ~JyLl '~1; tic anydride
The hydrocarbylcarbonyloxy moieties used in this
35 invention are preferably of a type found in the
conventional alkyd paints as described earlier. They
G:\cueooU7~9\5peo.13/12/94
214~8~
18
derive Al~tnlr;tq;~Ah;l;ty from the presence of ole~inic
unsaturation in a linear hydrocarbyl chain and the chain
will usually contain from 12 to 30 (u~ually 16 or 18)
carbon atoms.
The polyols used in this invention are also preferably
o~ the type described earlier for use in making alkyd
paints. In addition, propylated sorbitols may be used,
that is to say the product obtained by condensing at least
10 four (and preferably six) propylene oxide molecules with
sorbitol .
The chemical composition of the îilm- forming material
obtained from the simple two step esterification process
15 described above is very complex and this in turn leads to
unpredictability which complicates the formulation of
coating compositions. In particular it is difficult to
predict precisely how much residual autn~ Ahl e non-
polycarboxylate ester will be found in the film-forming
20 material. Deficiencies in the amount of A1ltn~ Ahle non-
polycarboxylate ester of the polyol cnnt~;n;ng at least
five hydroxyl groups have been found to lead to increased
amounts (for example 35 to 45wt90) of material having a
molecular weight in the range 10,000 to 100,000 which
25 adversely effects the viscosity of the ultimate paint. A
less complex and more predictable composition is obtainable
by using the so-called "split" two step process.
In the split two step process, both steps are split
30 into two parallel separate operations which produce
separate polycarboxylate esters and the separate
polycarboxylate esters are then blended together. More
particularly the two steps are split into two separate
operAtions such that
a) in the first step of the first operation, the
.
~ ~ ~D89\qrrr ~ 94
~, 21~
aromatic f9; rArh~n~ylic acid is reacted with the polyol
and the autn7r; r1; ~iqhl e hydrocarbylcarboxylic acid to
form a first mixture of precursor esters (which are
long oil alkyd esters) and this first mixture i9 then
reacted in the second step with the polycarboxylic
acid or anhydride and
b) in the first step of the second operation, the
polyol c~lntq;n;n~ at least five hydroxyl groups is
reacted with the auto~ ;qhl e hydrocarbylcarboxylic
acid to form a second mixture of precursor esters
(which are long oil non-alkyd esters) and this second
mixture is then reacted in the second step with the
polycarboxylic acid or anhydride and
the products of the f irst and second operations are then
blended together to produce the f ilm- f orming material .
Preferably the non-alkyd mixture of polycarboxylate esters
is blended with the alkyd mixture in a weight ratio of from
3 to 0.5:1. The split process has the additional advantage
of producing less (usually less then 35wt96 and generally 25
to 35wt90) material having a molecular weight in the range
3500 to 100,000 and more having a molecular weight above
100,000. It has also been discovered that the first
operation can be performed using polyols ct~ntq;n;n~ only 3
or 4 hydroxyl groups (eg pentaerythritol) whilst still
permitting the formulation or paints ~-nnt~;n;ng at least
85wt~ solids.
A modification of this invention makes possible the
rf:'rl~C' t of polyols c~nt~;n;ns at least five hydroxyls
by polyols cnnt;~;n;n~ only four hydroxyls (eg
pentaerythritol ) in any aspect of this invention and
especially in the production of autr~ hl e non-alkyd
polycarboxylate esters. The modification comprises
replacing the polyol cr~nt;-;n;ng at least five hydroxyl
r~ ~789~qr~ ~ 219~
2~0~9
groups with the molar equivalent amount of a notionally
coupled pair of polyols ct-nt~;n;ng at least four hydroxyl
groups which are coupled by means of a dicarboxylate link.
The polyols are at least notionally coupled in situ by
5 means of dicarboxylic acids/anhydrides such as adipic acid
or phthalic anhydride to make a polyol dicarboxylate. It
has been discovered that provided the approximate
stoichiometric molecular ratio of reactants is used, a
polyol dicarboxylate appears to be made which behaves like
10 dipentaerythritol in the formation of the illlt~ hl e
long oil polycarhoxylate ester. The precise stoichiometric
molar ratio is
AUtrY;~ hle hyd~ocarbylcarboxylic acid 15
4~hydroxy polyol 6
Dicarboxylic acid/anhydride 3
It is prefered that the molar ratio should not vary by
more than ~3~ from stoichiometric The precise nature of
20 the coupling action is too uncertain to merit simple
I~Yrl;ln~t;on, but it is believed that it results in the
production of film-forming material in which the
polycarboxylic acid/anhydride is esteri~ied by moieties
derived from a substituted at least notionally coupled pair
25 of polyllydr~J~y alcohols each of which ~ nt~;n~ at least
four hydroxyls prior to coupling and substitution by
hydrocarbylcarbonyloxy moieties and which are coupled by a
dicarboxylate link involving one hydroxyl from each alcohol
as indicated below:
CO2R CO2R
_0~ C02~Co2~ CO2R
CO2R CO2R
I~respective of how the film-forming material is made,
prior to its formulation into a coating composition, a
G~ o\17b9\5pec.13112/94
~ 21~û5~9
21
portion of it (pre~erably 5 to 159r) is converted to a co-
reaction product by chemically co-reacting it with 3 to 1596
of its weight of a polyamide or polyamine/polyisocyanate
c~-mhln~tlfm. Suitable polyamides are those used to impart
5 thixotropy to alkyd polymers and which are described for
example US 2 663 649 (the contents of which are herein
incorporated by reference) or DE 1 198 556. A typical
polyamide will comprise a polymer made by reacting a
dimerised fatty acid with a diamine such as ethylene
10 diamine. Preferably before the co-reaction, the polyamide
should have a weight average molecular weight of from 2,000
to 10, 000 and most preferably from 3, 000 to 5, 000 .
The co - reaction is conveniently perf ormed by heating
15 the film-forming material and polyamide together at from
180 to 230C whereupon the polyamide bonds to the film-
forming material. The co-reaction is also too complex to
permit a precise characterisation but it is presumed that
some interchange reactions occur possibly together with
20 reactions involving the evolution of water.
The co-reaction may alternatively be performed with a
polyamine/polyisocyanate combination instead of the
polyamide . In this case the co- reaction ig conveniently
25 performed by first mixing the film-forming material with an
amount of polyamine (preferably diamine) sufficient for the
combined weights of polyamine and polyisocyanate to equal
f rom 3 to 15 wt96 of the f ilm- f orming material . This
mixture is then heated to preferably 90 to 110C and an
30 amount of polyisocyanate is added whereupon the polyamine
and polyisocyanate react with each other and presumably co-
react in some way with the film-forming material to form an
essentially polyurea composition bonded to the film-forming
material. Again the product is too complex to permit
35 precise description but it is believed that the polyurea
bonds to the film-forming material by reaction with
('' '789~r~ 94
~ 2140S8~
22
carboxylic acid and hydroxyl groups remaining in the
material. Presumably a polyurea is formed by a reaction of
the type indicated below:
o
I (NC0) ~ + NH2RINH7 ~ I (NC-NHRINH- )
.
where I and Rl are the nuclei of the polyisocyanate and
the polyamine and n i8 preferably greater than 2.
Suitable polyureas may be obtained as described in
European Patent Specification EP 0 435 428B (published in
1993) or in corresponding United States Patent
Specification US 5 164 449 (the contents of which are
herein incorporated by reference). A particularly
preferred class of polyisocyanates are the isocyanurate
trimers such as proprietary heterocyclic material sold as
"Desmodur" N3300 available from ~3ayer AG of Leverkusen in
West Germany. "Desmodur" N3300 is believed to consist
mainly of the trimer of hexamethylene di-isocyanate and the
isocyanurate trimers are believed to have structures which
at least approximate to the following:
~ C~
0~
~/VC R o
where Rll is hp~m~thylene divalent linking moiety.
r~ 17144
~ 214~9
The polyamide- or polyurea-modi~ied ~ilm- ~orming
material (ie. the co-reaction product) is preferably
obtained by co - reacting f rom 5 to 15wt~ of the material
with the polyamide or polyamine/polyisocyanate , ' ;n~t;nn
5 away from the rest of the material and then mixing the co-
reacted material back with the un- co - reacted material .
This re-mixing of the materials i~ conveniently performed
at the same time as any non- f ilm- f orming material iB mixed
with the f ilm- f orming materials .
The co-reacted and un-co-reacted materials are
generally obtained as materials c~nt;~;n;ng less than lwt96
volatile organic solvent. They are then diluted with
volatile organic solvent (for example white spirit) to
15 facilitate mixing with each other and with non-film-forming
materials and to produce a coating composition which may
(if desired) contain as much as 85wt9~ or more of non-
volatile material whilst remaining brushable, that is to
say whilst having a viscosity of from 2 to 10 (and
20 typically 5) poise (ie. 0.2 to 1 or 0.5 Pa.sec). Bxamples
of non-film-forming materials are those conventionally used
in making for example paints, v~rn; Ch~L~ or woodstains
Such materials include pigments, dyes, extenders,
thickeners, fungicides, anti-flk;nn;ng agents, flow
25 illL,I)L~V~ and drying agents.
This invention also provide~ a modif ied aut~ hl e
film-forming material in which the film-forming material
includes e~ters of a polycarboxylic acid which c~n~;n~ at
30 least three carboxylic acid graups and/or e~ters of an
anhydride of such a polycarboxylic acid wherein the
esterifying moieties are chosen from
a) alkyd polymer moietie~,
b) m~ 3 derived from either a substituted polyol
or substituted polyol dicarboxylate c~nt~;n;ng at
r I~/12/9'.L
- 214~5~9
least f ive hydroxyls prior to substitution up to all
but one of which hydroxyls per polyol or polyol
carboxylate molecule have been substituted by
; fl; c::lhle hydrocarbylcarbonyloxy moieties and
optionally
c) moieties derived from a substituted polyol
c~,nt~'n;ng three or four hydroxyls prior to
substitution of which one or two per polyol molecule
have been substitut.ed by autoxidisable
hydrocarbylcarbonyloxy moieties
and a portion amounting to 5 to 15wt96 of the ~ilm-forming
material has been modified by co-reaction with polyamide or
polyamine/polyisocyanate combination in an amount such that
f rom 3 to 15wt~ of the f ilm- f orming material af ter
modification consists of moieties derived from the
polyamide or polyamine/polyisocyanate ~-.mh;n~t;on.
Preferably the modified film-forming material
comprises a blend of non-alkyd polycarboxylate ester
derived ~rom hydrocarbylcarboxyloxy substituted polyol
having originally at least f ive hydroxyls or polyol
dicarboxylate with alkyd polycarboxylate ester.
Aspects of the invention and its background are
illustrated by the drawings and graphic formulae shown in
the f igures of which
Figure 1 is a graph showing the distribution of molecular
weights in a conventional alkyd polymer used in
3 0 decorating architectural sur~aces at ambient
temperatures .
Figure 2 is a graph showing on a larger scale the
distribution of molecular weights in a film-
forming material made according to Example 1,
Part C of this Specification.
G:~c~oU.~,, . 1~117194
21405~9
igure 2A is a graph showing the distribution of molecular
weights in a film-forming material made according
to the modification of Example 1 described as
Example lA.
igure 3 is a graph showing the distribution of molecular
weights in a film-forming material made according
to Example 2 of this Specif ication .
0 Figure 4 is a graph showing the distribution of
molecular weights in a film-forming material of
the type made according to Example 3 of this
Specif ication .
5 Figure 5 is a graphic formula indicating the type of alkyd
polymer which can result from the two step
esterification as performed in Example 2 of this
Specif ication .
0 Figure 6 is a collection of graphic formulae of compounds
likely to be f ound in the f ilm- f orming material
made according to Example 2 of this
Specif ication.
The following techniques are used to measure various
properties ref erred to in this specif ication:
Gel Strength:
Gel strength is measured at 25C using a 40 by 20mm
blade in a Sheen Gel Strength Tester provided with 75mm
diameter 250ml capacity cylindrical sample can. The
procedure followed i~ described in Instruction I.eaflet REF
414 Gel Strength Tester published by Sheen Instruments
I,imited of Teddington England. The sample8 ~hould be
allowed to ~tand at 25C for 24 hours prior to performing
the tests.
.
C.~ 12194
21~05~
26
Molecular Weights:
The molecular weights of the various polymeric
materials were t9PtPrm;n~d by gel p~- -?tlnn c~romatography.
5 A 0 5wt~ solution of material in tetrahydrofuran was passed
at lml/min through cylindrical columns 300mm long by 20mm
diameter packed with a gel available from Polymer
Laboratories Limited of Church Stretton, England and known
as "Mixture D". The results obtained are calibrated
10 against a polystyrene standard.
Touch Dry time Meat~uL~ t:
The time taken for a freshly applied coating to become
15 dry to touch is measured by a sand deposition procedure as
f ollows:
A coating lOO~Im thick is applied at 20C to a
horizontal glass sheet. A hopper having a small outlet in
20 its base is filled with sand which then trickles through
the outlet. The hopper i8 caused to traverse the coating
at a speed of 25.4 mm/hour with sand trickling onto the
coating. Initially the sand sticks to the coating which is
still wet but as time passes, the coating dries and there
25 comes a point when the sand ceases to stick to it. The
time taken to reach this point is regarded as the touch dry
time for the purposes of this specification. The point i8
easily detected by blowing the loose sand from the fully
dried coating so as to leave a trail of stuck sand of a
30 length from which the touch dry time is calculated by
dividing by the speed of traverse.
This invention is illustrated by the following
35 Examples of which A to C are comparative. The "parts"
referred to in the Examples are parts by weight.
('' ` . ~1~2194
2~ 9
27
EXAMPLE 1
Coatlng Composition cnnt~n~n~ Film-Forming Material made
by a Split ~wo S~ep Esteri~ication:
a) i~ Fir~t Parallel Operation: Step one:
Preparation of a mixture of precursor autn~; fl; ~hl e long
oil non-alkyd esters by reacting together a polyol
originally rnnt;l;nln~ SiX hydroxyls (dipentaerythritol) and
10 an autoxidisable hydrocarbylcarboxylic acid (tall oil fatty
acid):
A 5 litre glass flask was fitted with a stirrer and a
Dean and Stark reflux condenser operable so as to allow the
15 escape of water from an azeotropic solvent. The flask was
purged with nitrogen and then charged with:
20 Charge Parts hy Wt. Wt%
Tall Oil Fatty acid (TOFA) 2444.7 83.4;
Dipentaerythritol 42 8 . 2 14 . 6
Xylene azeotropic solvent 57 . 0 2 . 0
25 The rn~lt~ntc of the flask were stirred and slowly heated to
240OC over a period of two hours Esterification occurred
in which TOFA esterified in the main about five of the
hydroxyl group~ of the dipentaerythritol and the water
produced was removed from the xylene via the separator.
30 Esterification was rnntln~ fl at 240C (adding extra xylene
to cool as nf~rrR~ry) until the acid value o~ the contents
had fallen to 3mgXOH/g of solids content. The contents
were then cooled to 120C
35 a) ii) First Parallel operation: Step two:
Preparation of an ~ltn~r;fl;~hle long oil non-alkyd
G:\c~o\P789\5pcc.13112/94
21~8~
28
polycarboxylate ester by reacting the product o~ Step one
above with trimellitic anhydride:
To the rnntc~nt~ coded to 120C obtained above were
5 added 107.9 parts by weight trimellitic anhydride. The
rr,nt~Qntc were re-heated to 240C whereupon esterification
of the anhydride occurred and was continued until the acid
value of the contents had fallen to between 8 and 10
mg~O~I/g of solids content. Finally the separator was
10 removed and the contents were i; subj ected to vacuum
distillation until the contents comprised from 99 to
99.5wt~ of non-volatile material which were found to have
a viscosity of 7 stokes at 2SoC.
The rrntPntCl 1 nrl ~ d the autr~xl ~ hl ,o long oil non-
alkyd trimellitate ester in which the esterifying groups
were penta (TOFAester) of dipentaerythrityl groups and
which trimellitate ester had an Mz molecular weight of
11, ~00 .
b) 1) Second Parallel Op~rat~rn: Step one:
Preparation oi~ a mixture of precursor long oil Alkyd
Polymers:
The procedure described in paragraph a) i) above was
25 followed but with the flask initially charged with the
f ollowing:
3 0 Charge Parts by Wt . Wt%
The fatty acid derived by the
hydrolysis of Soya bean oil (SOFA) 2102 . 3 73 . 3
Pentaerythritol 442 . 6 1~ . 4
Isophthalic acid 264.5 9.2
35 Xylene solvent 60 . 0 2 .1
G:\ccsel~o\r7~9;5pec.13/1~
214~9
29
b) il) Second Parallel Operation: Step two:
The procedure described in paragraph a) ii above was
followed except that the trimellictic anhydride was of
course added to the cooled product of b) i above and the
5 amount added was 142.9 parts by weight instead of 109.7.
The ~ nt~nt~ included a trimellitic ester in which the
esterifying groups were derived from alkyd polymers in
which the alkyd polymer chain con8isted of isophthalic acid
10 esterified by pentaerythritol in which hydroxy groups of
the pentaerythritol had reacted with moieties derived from
SOFA. The trimellitic ester had an Mz molecular weight of
105,000 and a visco~ity of 119 stokes when measured at 25C
as a 99 wt9~ solution in xylene.
c) Ma}~lng the film-forming material by bl~n'l~ns the
Mixtures of Ester~ made in Parts (a) and (b) above:
A blend of the penta (TOFA ester) of non-alkyd
dipentaerythrityl trimellitate with the alkyd trimellitate
was made by heating them each to 70 to 80C and then mixing
e~ual weights of the two together whil~t ~-;nt~;n;ng the
temperature at 70 to 80C. The blend was a film-forming
material having an Mz molecular weight of 98,000 with peaks
at 1,800, 2,500 and in the range 5,000 to 6,000. 30 wt% of
the film-forming material had a molecular weight in the
range 1,500 to 3,500 and about 10wt96 had a molecular weight
of above 100, 000. The Mz/Mn ratio was 5 17. The viscosity
at 25C measured on a 99 wt96 solution in xylene was 18
stokes. The distribution of molecular weights obtained is
illustrated by Figure 2.
d) Polyamide-modification of Film-Forming Material made in
Part (c) above:
1,, 11112/94
214~
Whilst the ~ilm-forming material made in Part (c) wa~
still at a temperature of 70 to 80C, a 25wt% portion o~ it
was removed and 7 wt~ (based on the weight of the portion)
of a proprietary polyamide known as "Eurelon" 935 (supplied
5 by Witco of Accrington, T,~nr~h- re, England) was stirred
into the portion. The portion was stirred and heated to
220C and m~in~;n~rl at that temperature for 3 hours. It
was then cooled to ambient temperature. The polyamide was
found to have reacted chemically with the trimellitate
10 esters .
e) Formulation of ~ Palnt:
The f ollowing ingredients were added to a
15 "Dispersomat" m--ixer at ambient temperature:
Ingredient parts by wt.
Unmodified Blend of Esters - 30
Polyamide-Modif ied Blend o~ Esters 11
20Rutile Titanium Dioxide Pigment 34
White Spirit Solvent 4
The agitator blade of the mixer wa8 operated at 1,500
rpm for 30 minutes. Stirring was r~ntlnll~d and the
25 following further ingredients were added:
Unmodi~ied blend of esters 10
lOwt~6 solution of cobalt autoxidation
catalys t o . 2 5
lOwt~ solution oi~ calcium autoxidation
catalyst 1. 00
18wt~6 solution of zirconium autoxidation
catalyst 1.40
.
r~ 2/94
21~0539
31
methyl ethyl ketoxime O . 4
White spirit solvent (to 5 poise viscosity) 7.95
5 Gentle stirring was resumed for 5 minutes and produced a
paint having a viscosity of 5 poise which theref ore could
be brushed onto an alkyd undercoated surface at 18C as
easily as conventional alkyd paint. The paint had a solids
content of 85 . 7wt96 .
f ) Testing the paint:
A primed surface was prepared by priming a hardboard
surface with "Dulux" Trade white alkyd wood primer
(available from ICI Paints of Slough, England) and then
15 allowing the primed surface to age at ambient temperatures
for seven days.
A coating lOOIlm thick of the paint was applied to the
primed surface using a block spreader and the surface was
20 mounted vertically. No sagging of the coating was observed
during the period of 30 minutes following application which
is the time when sagging is most likely to occur.
EXA2~PLE lA
Modi~ied Example 1
The procedure of the second step of the first parallel
operation of Example 1 (part a) ii) was performed on a
larger scale and modified slightly by stopping the
esterification of the trimellitic anhydride at an acid
35 value of 9 to llmg KOH/g instead of 8 to 10 mg KOH/g. In
practice, this meant that the acid value was about lmg
G:\ccseoo\1789\5pec.13/12/94
21~o9
.
32
KOH/g higher than that reached in Example 1. Otherwise the
procedure for making the film-forming material was the same
and the molecular weight distribution in the blend of
esters obtained in part (c) is illustrated by Figure 2A.
It will be seen from a comparison of Figures 2 and 2A that
the molecular weight distributions are similar. The Mz
molecular weight was 88, 800, the peak molecular weight
occurred at 2540, the Mz/Mw ratio was 4 . 6 and the viscosity
at 25C measured on a 99wt% solution in xylene was 20
stokes.
A paint was fn 1~t~ as in Example 1 and thinned by
adding enough white spirit to give a viscosity of 5 poise
The paint had a solids content of 85 . 7wt% . The paint was
found to have a Touch Dry Time of 2.5 hours. In addition,
coatings 10011m and 200~Lm thick were applied to a primed
hardboard surf ace as in the Touch Dry Time Measurement
Technique and the times taken f or the coatings to dry all
the way through were measured. They were 2 . 5 and 5 hours
2 0 respectively at 2 0 C .
EXI~MPLE 2
Coating Composition cnnt~lnlng Polycarboxylate Ester
Component made by the simple (ie non-split) Two Step
Esterification:
a) Step one:
The procedure of paragraph a) i) of Example 1 was
repeated except that the f ollowing were charged to the
flask 80 that in effect the procedures of paragraphs a) i
and a) ii were merged:
3 5 Charge Part~ by Wt Wt96
Tall Oil Fatty Acid (TOFA) 2306.6 78.6
G:\c~eco\D89 3pec.~3/1~194
.. . 21~589
33
Pentaerythritol 222 . 3 7 . 6
Dipentaerythritol 212.9 7.3
Isophthalic acid 132.8 4.5
Xylene (azeotropic solvent) 60 . 0 2 . 0
Also when the acid value had fallen to 3 mg~O~I/g
solids content, the amount of trimellitic anhydride added
was 125.4 parts instead of 107.9. Ag before the cnntf~ntc
were vacuum distilled to give 99 . 5wt~6 of non-volatile
10 contents which were then found to have a viscosity at 25C
of 18 stokes. The contents obtained are believed to
include a mixed trimellitate ester in which the esterifying
groups are both polysubstituted etheralkyl and alkyd
polymer groups in various proportions. The contents were
15 suitable f or use as a f ilm- f orming material . The f ilm-
forming material had a molecular weight of 35,000 with
peaks at 1,680 and 2,500 and 30 wt96 of the material had a
molecular weight in the range 1500 to 3500. The Mz to Mw
ratio was 2 . 9 .
The distribution of molecular weights obtained is
shown in Figure 3. A 25wt~ portion of the cnntf~ntc were
reacted with 7 wt96 (based on the weight of the portion) of
polyamide as in paragraph (d) of Example 1 and a paint was
25 made according to paragraph (e). It was found that a
brushable paint composition was obtained which had a
viscosity of 5 poise and a solids content of 85.5wt96.
When coated onto primed hardboard as in Example 1, the
paint perf ormed as well as conventional alkyd paints and
30 produced a dried coat which was as hard and scratch
resistant as a conventional alkyd coat af ter 48 hours .
EXAMPLE 3
35 Coating Composition cnnt~;n;ng film-forming material in
which the non-alkyd polycarboxylate ester is made using
r _ , ~112194
21~
34
pairs of pentaerythritol molecule~ notionally coupled by a
phthalate link in a split two step process.
a) i~ First Parallel Operation; Step one:
A 5 litre flask was fitted with a stirrer and a Dean
and Stark separator and condenser operable so as to allow
the removal of water from an azeotropic sovent. The flask
was purged with nitrogen and charged with:
Charge Parts by Wt96 Mol
weight Ratio
Tall oil fatty acid (TOFA) 2248.9 72.55 15
Pentaerythritol 421.9 13.61 6
15 Phthalic anhydride 229.9 7.42 3
Xylene (azeotropic solvent) 100.0 3.22
The contents of the flask were stirred and slowly heated
20 (under nitrogen) to 230C, over a period of 2 hours.
Esterification occurred and the water produced was removed
via the separator. Esterification was cr~nt;nllf~d until the
acid value of the esters had fallen below 5mg/EOH.gm of
solids content.
a) ii) First Parallel OperAtio~; Step Two:
The esters obtained in a) i) above were cooled to 120C
and 99.3 parts (3.20wt~) of trimellitic anhydride were
added. The mixture was re-heated to 230C whereupon
30 esterification of the anhydride occurred and was c~-nt;nl-Gd
at this temperature (adding additional xylene as necessary)
until the acid value of the system had fallen to between 8
and lOmgXO~I/gm of solids content. Finally the separator
was removed and the trimellitate ester subj ected to vacuum
35 distillation until the t~nt~ntc compri8ed from 9996 to 99.5~6
of non-volatile material which was found to have a
G:~c~o\1789\5p 13/12194
~ 21~05~9
viscoslty of 15 stokes at 25C. The trimellitate ester
comprised esterifying moieties which were penta TOFA esters
of dipentaerythrityl phthalate having a formula indicated
as shown below.
C07 R ~ ~ J~ co,~. ~ co7 R
t~ ~ C~L CV~ ~tCV~,~ C'J.+ C.~7 C~C4~
C~2R COi~ ~cd, ~ R
b) Second Parallel Operation: Steps one and two:
15 Steps one and two of the second parallel operation of
Example 1 were repeated.
c) Making t~e ~ forming material by bl~n~l~n~ the esters:
The esters obtalned according to parts a) and b) above were
20 blended as in part c) of Example 1 except that the blend
cnnt~lln~f~ 65wt96 of the trimellitate ester made according to
part a) and 35wt96 of the alkyd trimellitate ester made
according to part b) . The blend was a f ilm- f orming
material having an Mz of 2~8 with peaks at 1,800, 2,500
25 and in the range 5,000 to 6,000 27wt9~ of the material had
a molecular weight in the range 1,500 to 3,500 and the Mz
to Mw ratio was 5.17. The material had a viscosity at 25C
in a 99wt~ solution in xylene of 33 stokes.
A portion of the film-forming material was modified by
polyamide as in Example 1 and then a paint was made also as
in Example 1. The paint had a solids content of 85wt~.
Coatings 100,um thick of the paint were sag-resistant and
dried as ~uickly as those of conventional paints.
.
G ~cc~o\r78s~spcc~l3~
~ 214~
36
COMPARATIVE EXAMPLES A AND B
Importance of Co-Reacted ~olyamide
A f ilm- f orming material was made according to Example
but the material was not co - reacted with polyamide
In8tead, in Comparative Example A, no polyamide at all was
added to the blend and in Comparative Example B, a
conventional thixotropic agent was merely stirred into the
blend. The conventional thixotropic agent was made by
reacting a conv~ntl~n~l aut~T;~ hle alkyd polymer with
5wt~ (based on the weight of the polymer) of a polyamide
available as "Versamid" 930 from Cray Valley Products of
MAchen, Wales.
Coating compositions made using the f ilm- f orming
materials from Example A sag badly within 30 minutes of
being applied lOOIlm thick to a primed hardboard surface
which i8 hung vertically immediately after application of
the coating composition.
In the case of Example B, brushable coa~ing
compositions c~-nt~1n1n~ less than 15wt~ white spirit could
not be obtained. The compositions did not become brushable
until at least 25 wt96 white spirit had been added.
C ~l7~TIVE EXAMPLE C
Need for Alkyd Trimellitate:
The procedure of Example 1 was repeated except that
the addltion of trimellitic anhydride was omitted ~rom the
procedure of paragraphs b) i and ii. The coating
compositions sAgged badly within 30 minutes when applied
lOO~m thick to a pr~med hardboard surface which was hung
vertical immediately after app~ication of the coating
composition .
