Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
1994-11-10
2001-03-06
Bell, Mark L. (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S411000
Reexamination Certificate
active
06197103
ABSTRACT:
This specification describes an invention relating to a phthalocyanine composition and more especially to a composition containing a methylated copper phthalocyanine.
For the sake of brevity, copper phthalocyanine is hereinafter referred to as CuPc and the prefix, chloro-, alkyl- or methyl- is used to denote CuPc in which one or more of the sixteen peripheral hydrogen atoms is replaced by chlorine atoms or by alkyl or methyl groups respectively.
It is known that copper phthalocyanine can exist in several crystal forms which are commonly characterised by their X-ray diffraction spectra. Among known crystal forms, the beta-form has a greenish hue, whilst the alpha-form has a reddish hue. Both colour shades are desirable for the colouration of surface coatings and polymers. The beta-form is usually stable with regard to its crystal structure in the presence of solvents commonly used in the manufacture of paints, such as ethers, esters, ketones and especially aromatic hydrocarbon derived solvents. However, the alpha-form tends to recrystallise in the presence of such solvents, and this recrystallisation is associated with a decrease in colour strength and a bathochromic shift of hue. This change may only become apparent on storage for a long period, or at an elevated temperature, or in the presence of a large amount of an inorganic pigment, such as TiO
2
, or in a combination of these conditions.
Methods for inhibiting this tendency to recrystallise are known, see for example, “The Phthalocyanines, Vol.II, Manufacture and Applications” by Moser and Thomas, (1983, CRC Press). One method involves the replacement of some molecules of CuPc in the crystals of alpha-form CuPc by molecules of chloro-CuPc. However, as monochloro-CuPc is greener than alpha-form CuPc, this approach generally results in a significant bathochromic shift from the desirable reddish hue of alpha-form CuPc. Another proposed method (see GB 1,422,834) involves replacing up to 10% of the CuPc molecules with molecules of a C
3-9
-alkyl-CuPc which is alleged to inhibit recrystallisation without shifting the hue of the alpha-form CuPc because the alkyl-CuPc has a similar reddish hue.
It has now been surprisingly found that the partial replacement of CuPc molecules in alpha-form CuPc by methyl-CuPc will also inhibit the tendency of the alpha-form to recrystallise in the presence of the aforementioned solvents and thus inhibit a decrease in colour strength and a bathochromic hue shift, on storage.
According to the present invention there is provided a composition of copper phthalocyanines containing, on average, from 0.1 to 3 methyl groups per phthalocyanine nucleus.
The composition may comprise a mixture of methyl-CuPc having different numbers of methyl groups. Each methyl-CuPc in the composition may contain one, two, three or four methyl groups on the phthalocyanine nucleus and a typical composition may contain any or all of these together with CuPc which is free from methyl groups.
The composition preferably contains from 0.2 to 2.0, more preferably from 0.2 to 1.0, and especially from 0.3 to 0.7 methyl groups per phthalocyanine nucleus.
The phthalocyanine nucleus of any CuPc in the composition may carry up to 1 substituent group per phthalocyanine nucleus of another species, such as halogen, especially chlorine or bromine or C
1-4
-alkoxy, but is preferably unsubstituted.
A preferred composition comprises a mixture of two or more of the following species, monomethyl-CuPc, dimethyl-CuPc, trimethyl-CuPc and tetramethyl-CuPc and CuPc, with a preference for a preponderence of CuPc and monomethyl-CuPc. Where the phthalocyanine nucleus carries more than one methyl group, the methyl groups are preferably present on different peripheral benzene rings of the phthalocyanine nucleus.
The composition may be synthesised by partial replacement of the phthalic anhydride, phthalic acid or phthalonitrile used in the preparation of CuPc by an equivalent amount of methylphthalic anhydride, methylphthalic acid or methylphthalonitrile. To synthesise the composition directly, from 2.5% to 75% of the phthalic anhydride, phthalic acid or phthalonitrile used in the preparation of CuPc may be replaced by an equivalent amount of methylphthalic anhydride, methylphthalic acid or methylphthalonitrile. However, the present composition can be prepared indirectly, by the addition of a higher or lower proportion of methylphthalic anhydride, methylphthalic acid or methylphthalonitrile and sufficient CuPc or methyl-CuPc respectively is added subsequently to bring the number of methyl groups per phthalocyanine nucleus within the defined range.
According to a further feature of the present invention there is provided a composition as hereinbefore defined incorporating a deflocculating agent. In the context of the present application a deflocculating agent is one which enhances the resistance of the pigment to flocculation. Some of these agents also improve the fluidity of a dispersion of the pigment in an organic liquid.
A preferred deflocculating agent is a phthalocyanine, especially CuPc, carrying acidic or basic groups. The deflocculating agent preferably contains up to four acidic or basic groups which are preferably selected from acidic groups such as —SO
3
M and CO
2
M, in which M is H, alkali metal, ammonium or substituted ammonium, and from basic groups such as
in which
R
1
& R
2
are each independently H or C
1-4
-alkyl, and
R is alkylene, alkenylene, cycloalkylene or R, R
2
and R
3
together with the N atoms to which they are attached form an aliphatic heterocycle, such as pyrazine, any of which may be substituted by a group selected from halogen, especially chlorine, C
1-4
-alkoxy and hydroxy.
Examples of a suitable deflocculating agents are
CuPc(SO
3
H)
1-2
CuPc[SO
2
—NH—C
3
H
6
—N(CH
3
)
2
]
3-4
CuPc[CH
2
—N(CH
3
)
2
]
2-3
CuPc[CH
2
—NH
2
]
2-3
CuPc[CH
2
—NH—C
3
H
6
—N(CH
3
)
2
]
2-4
CuPc[CH
2
—NH—CH(CH
3
)
2
]
2-4
CuPc[CH
2
—O—(CO—[CH
2
]
17
—O)
6
—H]
3
The composition preferably contains up to 15%, more preferably from 4% to 10%, of the deflocculating agent.
The composition may contain other components which are typically present in commercial pigments such as surfactants and dispersants, resins, amines, especially fatty aliphatic amines, and preservatives
The pigment composition is preferably in a pigmentary form, that is in finely divided condition in which the average size of the pigment particles, along their longest axes, is below 10 micron and more preferably below 1 micron.
The composition may be converted into a pigmentary form in various ways.
(1) The composition, and optionally a deflocculating agent as hereinbefore described, may be milled in solid form, preferably in the presence of a grinding aid such as an inorganic salt, for example sodium chloride, carbonate or sulphate. The inorganic salt may be removed in a known manner, for example by solution in water, and the pigment composition may be dried.
(2) The composition, and optionally a deflocculating agent as hereinbefore described, may be dissolved in a solvent such as sulphuric acid, and precipitated by drowning the solution into a non-solvent such as water, preferably under turbulent mixing conditions.
(3) An aqueous suspension of the composition may be milled in the presence of a hydrolysable surfactant such as sodium decyl-sulphate. The surfactant may then be hydrolysed by an appropriate treatment with acid or base, and the surfactant and its hydrolytic products then partially or totally removed by filtration of the pigmentary form followed by washing with a liquid such as water. The pigmentary composition may then be dried.
(4) An aqueous suspension of the composition may be milled, optionally in the presence of a basic deflocculating agent as hereinbefore described, and in the presence of an acid such as acetic acid, and optionally in the presence of an organic solvent. Examples of such solvents are disclosed in UK patent 1113060. The suspension may then be basified to liberate the free
Davies Peter Kingsley
McCarthy John Michael
Schofield John David
Bell Mark L.
DiVerdi Michael J.
Pillsbury Madison & Sutro LLP
Zeneca Limited
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