Note: Descriptions are shown in the official language in which they were submitted.
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The-present inventiorl relates to a process
for the ~oduction of an azomethin~ pigment.
In British Patent Specification No. 1,254,336,
there is described a compound having the formula-
.
O,,.Cu ~O
in pigmentary form having a mean particle size notexceeding 2.0 microns. This specificatlon also discloses
processes for producing compound I, directly in pigmentary
form comprising either first reacting together 2-h~droxy-1-
naphthaldehyde and 2-aminophenol under aqueous alkaline
non-oxidising conditions9isolating and re-dispersing this
ligand and adding thereto, whilst applying mechanical stirring
to the mixture, an aqueous solution of a water-soluble
coppering aaent; alter~atively~ the metallisati~n step can
be effected directlv after formation of the lig~nd to which
has been added an excess of ammonium sulphate.
.. .
We have now ~ound that by modifying this direct
aqueous process by incorporating an additional step,
compound I is produced in a pigmentary form and having
lmproYed properties compared with the product of the un-modifi ed
process.
Accordin~ly, the presen~ invention provides a process
~or the production of a compound of formula:-
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in pigmentary form having a mean particle sizenot exceeding 2.0 mic.rons, comprising
a) first reacting together 2-hydroxy-1-napthaldehyde
and 2-aminophenol under aqueous alkaline non-
oxidising conditions~and e~ther neutralising the
reaction product or isolating the-reaction ~roduct
and re-dispersing it in aqueous medium and adding
to the neutralized or re-dispersed reaction production
whilst applying mechanical stirring to the mixture,
an aqueous solution of a coppering ageni,
b) separating the solid product, washing it
~xee ~rom inorganic salts and optionally drying it,
and
c) subjecting the dried pigmentary product to a kneading,
-- salt-milling or aqueous milling procedure.
In step (a), oxidation of the reactants ma~ be
~re~ented by excluding air from the reactor by the use of
an inert gas atmosphere~ ~or instance a nitrogen atmosphere,
however oxidation is prefera~ly prevented by the presence
of a reducing agent such as sodium bisulphite, sodium
dithionite, sodium sulphite or glucose in the reaction
mixture. If a reducing agcnt îs used, however, it may
be necessary to isolate the azomethine formed in the
reaction and re suspend it prior to coppering to a~oid the
reducing agent interfering in the subsequent coppering
reaction. The azomethine may be isolated for instance
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by the addition to the reaction m:ixture Or an acid which
may itself act as the reducing agent, for example sulphurous
acid. Alternatively, a reducing agent may be added with
the acid.
Coppering in step (a) may be carried out at
any temperature from ambient to 100C., preferably at
a temperature within the range of from 80 to 100C, using
an aqueous solution of` any water-soluble coppering agent.
Pre~erred coppering atents are copper acetate, cuprammonium
sulphate and sodium cuprotartrate. In order to effect
complete coppering, some mechanical stirring action must be
exerted on the suspension, for instance by vigorous agitation
or by the use of a high-speed mixer or other device.
Additions of a dispersing agent may be made, i~ desired, to
expedite the coppering reaction.
I~ step (c) of the process of the invention is
e~fected by means of a salt~grinding technique, the product
from step b) must have been dried and the salt may be any
metallic salt capable of removal on completion of the grindin~D
Examples of suitable salts are water-soluble salts remo~able
~rom ~he ground materlal by washing with water, for instance
alkali metal or alkaline earth metal salts of inorganic acids
or of C1-C4 alkanoic acids~ Specific examples of preferred
metal salts are calcium chloride, sodium chloride, sodium
acetate and mixtures thereof. These salts may be used alone
~r in conjunction with an organic solvent such as dimethyl-
aniline, diethylaniline or xylene.
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If an aqueous i~llling t~cl~nique is used in step (c),
the product from s~ep(b)l~i~ normally be wet and
a preferred arrangement is bead-milling e.g. in a
Sussmeyer Mill ~n the presence of solid spheres such as
metal, ceramic or glass balls.
The preparations according to the invention can be
manufactured particularly advantageously in a eontinuously-
working or batch-wise-working kneader. The material is pre-
ferably worked in the presence of a substance which assists
grinding3 preferably an inorganic salt, for example,
sodium chloride, potassium chloride, sodium sulphate or
barium chloride. These salts can be removed by eluting
with water in a simple mamler. Depending on the softening
point of the copolymer used, the pr~cess can be carried
out in the melt, however, it is usually advisable to add
an organic solvent, preferably an organic solvent which
is miscible with water, for example ethylene glycol,
glycerine, glycol monoethyl ether, methyl e~hyl ketone,
diacetone-alcohol or dimethylsulphoxide.
Instead of pure pigments, ready for use pigments
preparations can also be used, i.e. preparations which
contain in addition to the pigment for example 20 to
80%, preferably between 40 and 60%, of a carrier.
Suitable granulating assistants are preferably
synthetic, semi-synthetic and natural resins. The
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synthetic or semi-synthetic resins can be polymerisation,
polycondensation or polyaddition products In principle it
is possible to use all resins and binders commonly in use
in the paint and printing ink industry and described, for
exampl~, in the paint and varrlish raw materials tables of
Karsten, 4tho and 5th. edition, Hannover, 1967 and 1972
respectively, and/or in Wagner and Sarx's book on paint
resins, 5th, edition, Munich 1971. High molecular weight
compounds with plastic character~ as described for example
in the "Kunststoff_Taschenbuch"3 Carl Hanser Verlag, Munich
~18th. edition 1971), can also be used as granulating
assistants. It is pre~erred to use those resins which do not
react further chemically on contact with air or with
themselves and possibly crosslink.
Preferred classes of resin are:
(a) colophonium and its derivatives in all forms, for example
hydrogenated, dimerised or polymerised, esterified with mono-
hydric or polyhydric alcohols, with resin ~ormers, as for
example acrylic acid and butanedio~ or maleic acid and
pentaerythritol, modified colophonium resin, calcium or zinc
salts of colophonium, abietic acid and esters thereof; the
soluble phenolic resins modified wi~h colophonium and resins
based on acrylic compounds, as well as other natural resins9
as for example linseed oil varnish, shellack and other copals,
and water_soluble salts of rosinamine;
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(b~ maleic resins, oil_free alkyd resins, styrenated alkyd
res:ins, vinyl toluene modified alkyd resins, alkyd resins
with synthetic fatty acids, linseed oil alkyd resinsg
ricinenic alkyd resins, castor oil alkyd resins,soya oil
alkyd resins, coconut oil alkyd resins, tall oil and fish
oil alkyd resins and acrylated alkyd resins,
(c~ terpene resins and terpenephenol resins;
(d) polyvinyl resins, e.g.: polyvinyl acetate, polyvinyl
chloride and polyvinylidene chloride , polyvinyl acetals,
polyvinyl ethers, copolymers and graft copolymers with
different vinyl monomers, polyacrylic acid resins, as for
example acrylic and methacrylic esters and their copol~mers;
(e) styrene polymers and copolymers;
(f) polyolefins, polyethylene, polypropylene, polybutylene,
polyisobutylene, polyisoprene, substituted polyolefins,
halogenated polyole~ins and their copolymers, as for ex~mple
e~hylene and vinyl acetate copolymers and other synthetic
resins based on unsaturated hydrocarbons, e.g. low molecular
polystyrenes, and especially the polyolefins of average poly-
li2 marisation with a molecular weight of 300-5000 ~Rr~n~
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(g) polyamide and polyester resins5 as for example linear or
branched polyester resins based on phthalic acid, adipic acid
or sebacic acid;
(h) coumarone, indene, coumarone_indene and ketone resins;
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73:~
(i) cellulose derivatives, e.g. cellulose ethers, as for
example ethyl cellulose and benzyl cellulose in ordinary
commercial form, and also cellulose esters, as for example
cellulose acetate, cellulose acetobutyrate and nitrocellulose,
which can also be undernitrated.
The pigment produced in accordance with the
present invention may give shades ranging from greenish
yellow to ~eddish yellow depending on the methods of
preparation and pigmentation employed. The pigment
produced is suitable for use in the pigmentation of high
molecular weight hydrophobic organic or other organic
materials. The pigment is distinguished by-its high
colour strength, high resistance to solvents, outstandingly
good fastness to overprinting and especially by its
resistance to weathering when incorporated into surface
coatings. The pigment Or this invention is suitable, for
example, for use in the pigmentation o~ high molecular ~eight
hydrophobic organic material, for instance of paints,
.lacquers, printing inks, rubber, synthetic polymeric
materials, paper and textile materials. In general,
the pigment of the present invention exhibits good fastness
properties especially to light, heat, cross-lacquering
and migration, and resistance to organic solvents, such
as trichloroethylene, toluene and methyl ethyl l~etone.
Comp~red with pigments of formula I produced without
~tep (c) of the process of the invention, the pigment
produced according to the invention is cleaner, more trans- . ..
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parent and exhibits higher gloss in automotive paint
systcms.
The prcsent in~ention also provides a compositlon
comprising an organic material and a pigment of formula I
produced according to the proces.s o~ the invent~on, as
her~inbefore defined; as well as a method of colouring
or~anic ma-terial comprising incorporating therein the
pigmcntary product of '~he process of the present invention.
~ he high molecular weight hydrophobic organic material
or other org~nic material to be coloured may bc any polymeric
or other organic material capable of being pigmented oY~
o~herwise coloured. The material may be, for instance,
a natural or synthetic polymer or copolymer, a coating
oomposition for application to the sur~ace o~ an article,
or a printing liquid medium. Howe~er, prererred materials
are natural or synthetic pol~;mers o~ co-polymers, in the
~orm offilms or bulk material; paints) lacquers and other
surface coating compositions, or tinting compositions for
use ~n preparing such coating compositions; and printing iA~
Examples o~ polyn-ers o~ co-pol)~ers which may be pigmented
i~cl~de ~inyl chloride polymers and co-polymers; polyethylene,
polyacrylonitrile, polypropylene and other polyole~ines;
polystyrene and pol)styrene co-poly~ers; and natural and
~ynthetic rubbersO
~ le pre~ent invention is further illustrated by the
following Examples. Parts and percentage shown therein are
expressed by weight. In Examples 1 to 7 the resulting
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p:l gment was found to have a mean pa:rticle siz~ not
exc~ding 2 . O microns .
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Examp~e 1
a) 17.2 Parts of 2-hydroxy~1-naphthaldehyde and 10.9
parts of 2-aminophenol were added to 150 par*s of
water, with stirri~g~ A solution of 4.2 parts of sodium
hydroxide in 50 parts of water was added followed by
15.6 parts of sodium bisulphite. The resulting suspension
was heated to 90~C. and stirred. The product was
~iltered of~ and washed with water. The washed product
was slurried in 250 parts of water with high-speed shear
agitation. A solution of cuprammonium sulphate, prepared
by dissolving 27~5 parts of copper sulphate crystals in
100 parts of water and adding concentrated a~nonium
hydroxide solution until the initial precipitate had re-
dissolved, was added. The resulting mixture was heated
to 95co and stirred. The product ~as filtered off~
washed with water and dried. These were thus obtained
33 parts of green powder, having a copper content of 19.75~o.
(b) 25 parts of the product from part (a) were gro~nd
w~ 6~ parts Or a~ydrous calcium chloride, tO parts of
anl~drous sodium acetate and 205 parts of diethylaniline
for 6 hours. The salt/pigment mixiure was dischar~cd,
ad~ed to aq~eo~s acetic acid and stirred for 1 hour at 60C~
Th~ ~igment was isolated by filtration, washed free fronl
acid and sal1; and dried at 60C. The pigment so obtained
was cleaner and greener~ Inore transparent and had l~ er
gloss in aut~motive paint systems than the product fro~
part (a).
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~xamplc ?
Simila~ results ~ere obtained when the anhydrous
calciwn chloride used in ~.~ample 1 ~as replaced by
anhydrous sodium suiphate.
Exam~le ~
Similar results were obtained when Example 1 was
repeated but using 3.75 parts of diethylaniline and milling
for 4 hours.
~a ~
,
20 parts of the product ~rom ~xample l(a) was ground
for 16 hours in 200 parts of water using a Sussmeyer Mill
and 1 mm. diameter glass beads as t~le grinding elei~ents.
The gl~ss beads were then removed by sieving and the pigment
was isolated by filtration and drying at 50C.
e pi~me~t s~ obtained was stronger, cleaner~
~lightly redder, more transparent and had a higher gloss
in an a~tomoti~re paint system than the product of
Example t(a).
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Example 5
The following constituents are placed into a
laboratory kneader (nominal volume ~50 ml):
25 g of pigment according to Example la,
100 g of finely ground NaCl and
30 g of diacetone alcohol.
The mixture is kneaded for 5 hours with cooling. The
kneaded material is subsequently taken up in 4 litres of
water so that the NaCl and solvent become dissolved. The
suspension is filtered on a suction filter; the residue
is washed with as much water as required until free from
salt and solvent, and the filter cake obtained is dried
in a vacuum chamber at 80.
The resulting pigment produces in lacquers dyein~s
having a high degree of transparency and a very good lustre.
~ .
If the procedure is carried out as in Example 5
with the exception that there is added to the kneaded
~ .~
L~ material 2.78 g of Staybelite Resin (HERCULES), then there
is obtained a pigment containing 10% of resin~ which pigment
is characterised by the property of being more easily
incorpo~ated and by better dispersibility.
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Example 7
~ pigment preparation which can be incorporated into
lacquers with little effort by simple stirring, e.g.
with a dissolver, and which produces lacquer dyeings 7
especially also in metallised lacquers 9 having outstanding
transparency and an excellent lustre is obtained by
processing a composition in a kneading apparatus as
follows:
80 parts of pigment according to Example la,
120 parts of cellulose acetatebutyrate
B (~531-1; Eastman),
400 parts of finely ground NaCl, and
120 parts of diacetone alcohol.
are kneaded for 4 hours at 70C. The kneaded material is
di~n~ratedby the addition of 150 parts of water, and then
granulated in the kneader for one hour with cooling. The
granulate is suspended in ~4000 parts of water, and to
obtain maximum fineness of granulation the suspension is
passed through a colloid mill. ~iltration
is subsequently performed; the residue is washed with as
much wa~er as required u~til free from salt and solvent,
and the resulting filter cake is dried at 80 in a vacuum
chamber. There is obtained a yellow preparation having a
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pigment content of 40% and being of the aforementioned
excellent quality, which preparation can be used, e.g., for
the dyeing of lacquers.
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