Note: Descriptions are shown in the official language in which they were submitted.
2~2S~
0 94/23344 PCT/GB94/00654
COMPOSITION AND Y5E
The present lnvention relates to the use of di- or
trivalent metal salts of a n~rhth~lene oxy-carboxylic acid compound
containing a hydroxy group and a carboxylic acid group attached to
adjacent carbon atoms of an aromatic ring as a negative charging
charge control agent and to compositions COntAini n~ such a salt.
It has already been proposed to use anionic metal
complexes as charge control agents (hereinafter referred to as CCA' B)
in electro-,e~LoyLa~hic imaging processes. For example, EP 162,632
discloses toner compositions cont~ining 2:1 cobalt complexes of simple
azo ~hL~ u~hores and more recently US 5,143,809 discloses polyester
resin toner compositions contA;ning an anionic 2:1 zinc complex of an
aromatic oxy-carboxylic acid compound. None of these compounds are
entirely satisfactory as CCA's. Those disclosed in EP 162,632 are
coloured molecules which limits their use and as with those disclosed
in US 5,143,809 they are charged molecules which can interfere with
their formulation in toner compositions or toner-resin compositions.
Furthermore, industry is constantly requiring simpler and more
effective compounds as CCA's. we have now found that simple metal
salts of a n~rhth~lene oxy-carboxylic acid comroun~ cont~inin~ a
hydroxy group and a carboxylic acid group attached to adjacent carbon
atoms of an aromatic ring are suitable as a negative-charging CCA in a
toner composition for electro-Le~LoyLaphic imaging processing.
According to the invention, there is provided a toner
resin composition comprising a toner resin and a negative charging CCA
which is a di- or trivalent metal salt of a nArhthAlene oxy-carboxylic
acid wherein the hydroxy group and the carboxylic acid grqup are
attached to adjacent carbon atoms of an aromatic ring. Preferably the
. salt has a formula I.
~C;O-
n
W O 94/23344 PCT/GB94/00654
2~2~4
wherein
X is optionally substituted C1 12-alkyl which may be linear
or branched, alkenyl, hydroxy, halogen, nitrile, nitro, amino,
substituted amino, aryl, alkaryl, aralkyl, acyl, acyloxy, alkoxy,
alkoxy carbonyl, alkyl or aryl sulphonyl, carbonamide or snl~h~n~mide;
p is 0 to 6;
M is a divalent or trivalent metal cation; and
n is 2 or 3.
The group X is selected to enhAnce the compatibility of
the salt in the toner resin.
When X is alkyl, it is preferably methyl, ethyl,
isopropyl, t.butyl, amyl, hexyl, nonyl, decyl or dodecyl. When X is
halogen, it is preferably fluorine, bromine and especially chlorine.
When X is substituted amino, it is preferably C~-alkylamino such as
diethylamino, dibutylamino, hexylamino and 2-etllylhexylamino. When X
i8 aryl or aralkyl it is preferably phenyl, benzyl or ethylphenyl.
When X is acyl, acyloxy, alkoxy or alkoxycarbonyl it preferably
cont~n~ a Cl l2-alkyl moiety.
Preferably, p is 0,1 or 2, and e~pecially 0.
When p is not 0, X is preferably allcyl, and it is also
preferred that X is located in the 5 and/or 7 position of the
n~rhthAlene ring.
Examples of suitable nArhth~lene oxy-carboxylic acids are
2-hydroxy-3-nArhth~ic acid, 2-hydroxy-l-nArhthoic acid, 8-hydroxy-1-
n~rhth~ic acid, 1-hydroxy-2-n~rhthoic acid and derivatives thereof
such as 5,7-ditertiarybutyl-3-hydroxy-2-naphoic acid.
When M is a divalent metal cation, the metal is preferably
one from groups 2a, lb or 2b of the Periodic Table by Mendeleef as
published for example in the Handbook of Chemistry and Physics,
published by The Chemical Rubber Company. When M is a trivalent metal
cation, the metal is preferably one from either group 8 or group 3a of
the Periodic Table. When the metal is divalent it is preferably
calcium or magnesium and especially zinc. When the metal is trivalent
it is preferably iron or aluminium.
The toner resin is a thermoplastic resin suitable for use
in the preparation of toner compositions. A preferred toner resin i9
a styrene or substituted styrene polymer or copolymer such as
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0 94/23344 3 PCT/GB94/00654
polystyrene or styrene-butadiene copolymer.
It is especially preferred that the toner resin is a
! styrene-acrylic copolymer such as a styrene-butyl methacrylate
copolymer. Other suitable toner resins are polyesters, especially
alkoxylated bis-phenol based polyester resins such as those described
in US 5,143,809, polyvinyl acetate, polyalk~nes, poly(vinyl chloride),
polyurethanes, polyamides, silicones, epoxy resins and phenolic
resins. Further examples of these and other resins are given in the
book "Electrophotography" by R M Schafert (Focal Press); UK 2,090,008,
US 4,206,064 and US 4,407,924.
The toner resin composition may co~t~Ain more than one CCA
of formula I. The CCA is present in the composition from 0.1 to 12~,
preferably from 0.5 to 10~ and especially from l to 3~ by weight of
the total composition.
The toner resin composition may also cont~in a dyestuff or
pigment as colourant. Thus, according to a further feature of the
invention there is provided a toner resin composition as hereinbefore
defined which further comprises a colourant. The colourant is
preferably a pigment such as carbon black, metallised phthAlo-
cyanines, quinacridones, pèrylenes, benzidines, nigrosines, anilines,
quinolines, anthraquinnn~.s, metallised lakes and pigment toners and
water insoluble salts of basic dyes. The colourant may also be a
water soluble basic dye, especially a triphenylmethane dyestuff. The
toner composition may co~tAin up to 20~ colourant and especially from
3 to 10~ relative to the total weight of the toner resin composition.
The toner resin composition may be prepared by any method
known to the art which typically involves mixing the toner resin with
the CCA of formula I and optionally the colourant by kneA~ing in a
ball mill above the melting point of the resin. Generally, this
involves mixing the molten composition for several hours at
temperatures from 120 to 200C, in order to uniformly distribute the
J CCA and colourant (if present) throughout the toner resin. The toner
resin is then cooled, crushed and micronised until the mean diameter
of the particles is preferably below 20~ and, for high resolution
electro-reprography, more preferably from l to 10~. The powdered
colour toner or toner-resin so obtained may be used directly or may be
diluted with an inert solid diluent such as fine silica by mixing for
W O 94/23344 PCT/GB94/00654
2~L~g2~1
example in a suitable blending m~chine~
The CCA's of formula I are prepared by any method known in
the art and are conveniently made by dispersing the oxy-carboxylic
acid in water and/or a hydrophilic solvent and then adding an aqueous
solution of an alkali metal hydroxide in substantially stoichiometric
amounts to dissolve the oxy-carboxylic acid. Stoichiometric amounts
of a water soluble salt of the metal M are then added and the reaction
mix stirred until the reaction is complete and the metal salt M of the
carboxylic acid separates and is collected by normal methods known to
the art, such as by filtration and washing. The formation of the
alkali metal salt of the oxy-carboxylic acid and its salt with the
metal M is normally effected at temperatures below 60C, and
preferably at temperature from 20 to 25C. Mixtures of different
metals may be used as the water soluble salt, but it is preferred to
use single metals. Similarly, different oxy-carboxylic acids may be
used simultaneously which results in CCA's having different
substituents in the ~Ap~thAIene ring in the CCA of formula I. It is
preferred however, that only a single oxy-carbo~tylic acid is used.
The CCA of formula I is particularly well suited for use
in electro- e~oyLaphic imaging processes on account of ease of
dispersability in the resin, stability to processing and high charge
capacity. The zinc and aluminium salts are especially useful since
they are colourless and therefore can be used with a wide range of
colourants for producing different coloured toner-resin compositions.
The invention is now further illu8trated by the following
non-limiting examples wherein all parts and percentages are by weight
unless stated to the contrary.
Pre~arat~on of Zinc Salt of 3-HY~AY-2-Na~ththo~c Acld (CC 1)
3-hydroxy-2-napthoic acid ~27.3 parts) was stirred at room
temperature in 145 cm3 M sodium hydroxide solution plus 50 cm3 water
until the bulk of the acid had dissolved.
To the above wêll stirred suspension was added dropwise a
solution of zinc sulphate heptahydrate ~20.9 parts) in about 100 cm3
water. Further aliquots of water were added during the addition to
make the mixture more stirrable. When the addition had been completed
4/23344 2 ~ .~ 6 ~ 5 ~ PCT/GBg4/00654
the mixture was stirred a further one hour, then filtered and the
solid product washed well with water and dried at 45C to constant
weight.
A yield of 32.1 parts of a solid having a melting point in
excess of 300C was obtained.
By micro-analysis, the product was found to contain
C 55.6~ wt; H 3.9~ wt; and Zn 13.5~ wt.
Theory for C22Hl~OcZn.2H20 is
C 5S.6~ wt; H 3.8~ wt; and Zn 13.7~ wt.
The proportion of water was determined by Karl ~ischer
analysis and found to be 7.3~ wt. Theory for the zinc salt of
3-hydroxy-2-naph~h~ic acid dihydrate is 7.6~ wt.
P~.a~tlon of C~l~l S~lt of 3-H~ ~Y-2-N~nh~h~ r ACid (CCA 2)
3-hydroxy-2-napthoic acid (376 parts) was added to about
1.5 dm3 of water, which was m-int~;n~ at a temperature of 50C in a
5 dm3 beaker. The mixture wa3 stirred and a solution of 80 parts (2
moles) of 80~ r hydroxide in one dm3 of water was added in a thin
stream giving a colour change from yellow to dark brown.
A solution of calcium chloride dihydrate (147 parts, l.OM)
in 200 cm3 of water was added to the stirred mixture. On completing
the addition, a cream-beige solid precipitated. The mixture was
stirred for three hours at ambient temperature and the solid was then
filtered off and thoroughly washed with water until the filtrate was
free from chloride ion. The product was dried to constant weight in
an oven at 50C.
A yield of 380.22 parts of a cream coloured solid was
obtained.
By micro-analysis, the product was found to co~t~jn
C 56.4~ wt; H 4 . 2~ wt; and Ca 8.0~ wt.
Theory for C22Hl~06Ca.3H20 is
C 56.4~ wt; H 4.3~ Wt; and Ca 8.5~ wt.
The ~Lu~oL~ion of water was determined by Karl Fischer
analysis and found to be 11. 4~ wt. Theory for the calcium salt of
3-hydroxy-2 -n~rhthoic acid trihydrate is 11.5~ wt.
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2 ~ 4
Pre~aration of Zinc Salt of 2-HYJL~ Na~hthoic Acid (CCA 3)
2-hydroxy-1-naphthoic acid (10.6 parts) was stirred with
100 cm3 of water at 50C. A solution of sodium hydroxide ~2.26 parts)
in 25 cm3 of water was added to the stirred mixture to give a dark
brown solution.
Zinc chloride (3.83 parts) was dissolved in 20 cm3 of
water and the solution was added to the dark brown solution. A
precipitate was formed and was stirred for 30 minutes. The mixture
was cooled and filtered. The precipitate was washed thoroughly with
water to remove chloride ion. The solid was dried to con-~tant weight
in an oven at 50C.
A yield of 12.53 parts of solid ~as obtained.
By micro-analysis, the product was found to contAin
lS C 55.8~ wt; H3.9~ wt; and Zn 13.5~ wt.
Theory for C22H1~O~Zn.2H2O is
C 55.6~ wt; H 3.8~ wt; and Zn 13.7~ wt.
The proportion of water was determined by Karl Fischer
analysis and found to be 7.6~ wt. Theory for the zinc salt of
2-hydroxy-l-napthoic acid dihydrate is 7.6~ wt.
PreDaratlon of Zinc Salt of l-~YdL~Y--2-Na~thtoic ACld (CCA 4)
1-hydroxy-2-napthoic acid (47 parts) was stirred with
150 cm3 of water at 50C. A solution of lOg of sodium hydroxide in
100 cm3 of water was added and a dark brown solution was formed.
Zinc chloride (17.05 parts) in 25 cm3 of water were added
to the dark brown solution. A precipitate formed. The mixture was
stirred for 30 minutes, cooled and filtered. The precipitate was
thoroughly washed with water to remove chloride ion and was dried in
an oven at 50C.
Pre~aration of Iron (III) Salt of 3-Hy~h~Y-2-Na~hthoic ~cid (CCA 5)
3-hydroxy-2-naphthoic acid (30.1 parts, 0.16M) was stirred
with water (200 ml) and a solution of sodium hydroxide (6.4 parts,
0.16 M) in water (65 ml) was added. After heating to 50~C, the
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0 94/23344 PCT/GB94/00654
n~phthnic acid dissolved and a solution of ferric chloride hexahydrate
(8.65 parts, 0.053 M) in water (15 mls) was added. The reactants were
stirred at 50C for a further 15 minutes to form the ferric salt.
After cooling, the ferric salt was filtered, washed with water and
dried (Yield ~ 19.07 parts, 53~ theory).
The analysis was consistent with the empirical formula
FeC33H2l0g 3H20
P ~a 4~ion of the Al~lnlum Sal~ of 3-l.Y~ -2-~r~th~ c Acld (CCA
6)
This was prepared in analogous manner to that described in
Example 4 except that the ferric chloride was replaced by the molar
equivalent of aluminium chloride.
Analysis was consistent with the empirical formula
AlC33H2lO3-3H2O-
~XAMPLE 1
A toner-resin was prepared by kneA~ing at 150C for 30
minutes in a mixture of a styrene-acrylic resin ~920 parts; HIMER
TBlO00) and CCA 1 ~0.5 parts). The resin was then cooled and
pulverised to give an average particle size of 10 to 12~.
EXAMP~E 2
The toner-resin from Example 1 was converted into a toner
composition by kne~ing 93 parts of the resin with carbon black ~7
parts; ELFTEX 415) at 160C for 3 hours. After cooling, the
composition was ground and pulverised until the mean particals size of
the composition was below 10~. The toner-resin composition obtained
is hereinafter referred to as TRC 1.
EXAMPLE 3
A developer was prepared by mixing TRC 1 (lO parts) as
described in Example 2 with ferrite iron particles (90 parts) having
an average particle size of 40~. The developer was found to have an
WO 94/23344 PCT/GB94/00654 ~
21 5~2~ ~
initial triboelectric charge of -16~ C.gm~1 as determined by the
standard 'Blow Off' method described by Schein (J. App Physics, 46
(1975) p5140 using a Toshiba TB 200 "Blow Off'~ machine.
~P~E 4
~roDaratlon of Toner Resins
Acrylic resin (300 parts; Almacryl B-1500 resin ex Image
Polymers Europe, Waalwijk, Netherlands~ and a metal bonate (7.5 parts)
were mixed together in a Z-blade mixer for 60 minutes at between 160
and 180C. After cooling the crude toner resin was ground and then
pulverised in a mill with steel balls for 6 days until the particle
size was reduced to between 5 and 20~.
~MæT-~ 5
Sr~ h~ h-~e MQ~ 1 t
The ground toner-resin from Example 4 (0.4 parts) was
mixed with an uncoated iron powder carrier (19.6 parts, RAV-270 ex
Powder Technology, USA) in an aluminium tin on a roller mill for 1
hour. The developer so obtained was evaluated on a Toshiba TB 200
~Blow off~ m~rh;ne and the tribocharge was measured after 2, 10, 20
and 30 minutes. The results are given in Table 1 below which show
that the CCA developer obtained from iron (III) and aluminium attains
a higher charge than that of the zinc and calcium bonate.
TART~
Developer Metal Tribocharge (~cg~1) after time (mins)
2 10 20 30
C Q 1 Zn -19 -24 -25 -27
C Q 2 Ca -18 -22 -24 -26
CCA 5 Fe -26 -33 -37 -38
CCA 6 Al -22 -30 -33 -34
