Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
1999-08-17
2001-09-18
Green, Anthony (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S031720, C106S499000, C106S500000, C106S505000
Reexamination Certificate
active
06290768
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
The present invention is described in the German priority application No. 198 37 302.3, filed Aug. 18, 1998, which is hereby incorporated by reference as is fully disclosed herein.
BACKGROUND OF THE INVENTION
The invention relates to pigment preparations which are covered with a new kind of resin base and which when used as printing inks for offset printing exhibit improved rheological properties.
It is known that resinated pigments possess enhanced color strength, gloss, transparency and good dispersibility in the application medium for offset printing inks.
Simple natural resins based on rosin have been found to be particularly suitable for pigment preparation. Rosin consists of a mixture of various resin acids, predominantly abietic acid, pimaric acid and derivatives thereof. Resins based on rosin are often modified chemically owing to their sensitivity to oxidation, such modification being brought about, for example, by disproportionation or hydrogenation. These chemical derivatives of the natural resin acids possess an average molar mass of about 300 g mol
−1
. These resin types are therefore referred to as low molecular mass resins. However, when used in modern offset printing inks, the pigments prepared with these rosin derivatives have a tendency to mist. Misting means that, in the roll nips of modem, high-speed offset rotary presses, especially between the inking rollers and the printing plate cylinder, the printing ink tends to form an aerosol. The aerosol comes about through the breakup of threads of printing ink which are formed in the course of the spreading of the printing ink on the exit side of the roll nips. The fine ink mist soils the printing presses and pollutes the ambient air.
SUMMARY OF THE INVENTION
It is therefore an object to prepare printing-ink pigments such that they lose their tendency to mist but do justice to the high performance requirements in offset printing inks, such as suitable rheology and high color strength. It has been found that pigments prepared with defined resol-modified resin acid derivatives having an average molar mass of from 400 to 10,000 g/mol surprisingly achieve this object.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention therefore provides pigment preparations comprising an organic pigment and a phenol-modified natural resin derivative having a weight-average molecular weight (M
w
) of from 400 to 10,000 g/mol which is obtainable by reacting a mixture of reactants containing
a) from 50 to 95% by weight of natural resin or natural resin acids,
b) from 0.5 to 30% by weight of monocyclic or polycyclic phenols,
c) from 0.01 to 15% by weight of aldehydes or aldehyde acetals,
d) from 0.001 to 2% by weight of metal compounds from groups Ia and IIa of the Periodic Table, and
e) from 4.489 to 30% by weight of &agr;,&bgr;-ethylenically unsaturated carboxylic acids or their anhydrides
and has an acid number in the range from 160 to 300 mg of KOH per g of resin, preferably from 200 to 260 mg of KOH per g of resin.
The proportions specified for components a) to e) are always based on the sum of all components, which is always 100% by weight. By varying the proportions of components it is possible to tailor the solubility in dilute sodium hydroxide solution, the molecular weight and the pigment wettability to the desired levels. Preference is given to those phenol-modified natural resin derivatives which are soluble to form clear solutions in at least 10% strength by weight sodium hydroxide solution.
Examples of suitable natural resins or natural resin acids a) are rosin (tree resin), tall resin, roof resin or partially hydrogenated, disproportionated and dimerized natural resins.
The phenol component b) consists of monocyclic or polycyclic phenols. Use may be made, for example, of phenol, various cresols, butylphenol, amylphenol, nonylphenol, octylphenol, phenylphenol and bisphenol A, which have a functionality of two or more with respect to oxo compounds; mixtures of nonylphenol and bisphenol A are particularly preferred. The preferred proportion of components b) in the natural resin derivatives is from 1 to 25% by weight, in particular from 1.5 to 10% by weight.
As aldehyde component or aldehyde acetal component c) it is preferred to employ the aldehydes and aldehyde acetals normally used for preparing resols and novolaks. In particular, formaldehyde in aqueous solution or in oligomeric or polymeric form is used; paraformaldehyde is particularly preferred. Component c) is present in natural resin derivatives preferably in a proportion of from 0.02 to 10% by weight, in particular from 0.05 to 7% by weight.
Examples of suitable metal compounds d) from groups Ia and IIa of the Periodic Table are metal oxides and metal hydroxides or carboxylate salts of these metals. Particular preference is given to sodium salts or their aqueous solutions, especially sodium hydroxide. The metal compound d) is present in a proportion of preferably 0.002 to 1.8% by weight, in particular from 0.005 to 1% by weight.
As &agr;,&bgr;-ethylenically unsaturated carboxylic acids or their anhydrides e) it is possible preferably to employ aliphatic or aromatic/aliphatic carboxylic acids having 3 to 22 carbon atoms, especially methacrylic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid or cinnamic acid; acrylic acid is particularly preferred. Component e) is present preferably in a proportion of form 5 to 20% by weight.
The preparation of the phenol-modified natural resin derivatives is carried out by reacting components a) to e) in solution or, preferably, in bulk at temperatures in the range from 100° C. to 300° C., preferably from 110° C. to 280° C. and, in particular, from 140° C. to 260° C. For this purpose either the entire mixture of all components employed is reacted or individual components are introduced and the remainder are reacted by metered addition. The reaction is conducted such that natural resins or natural resin acids from group a) are reacted with &agr;,&bgr;-ethylenically unsaturated carboxylic acids or their anhydrides from group e) in the temperature range from preferably 140 to 240° C., are mixed with phenolic components from group b), aldehyde components from group c) and a metal compound from group d) and are reacted at a temperature of from 100 to 260° C., preferably from 110 to 160° C., preferably under a pressure of between 1 and 10 bar, in particular from 1 to 5 bar.
Instead of phenol and aldehyde, or else proportionately with them, it is possible to use a phenol-formaldehyde condensation product prepared separately by known methods from phenols and aldehydes in the presence of basic catalysts at a temperature of from 50 to 160° C., preferably from 60 to 100° C., and at atmospheric or elevated pressure. If a separately prepared phenol-formaldehyde condensation product is used, then it is possible to operate under atmospheric pressure. In a deviation from the above process, the condensation product of the phenol components b) and aldehyde components c) can also be prepared advantageously in situ in the resin melt. In the case of this reaction regime, which is energetically more favorable and in which a higher aldehyde conversion is achieved, first of all the natural resin acids from group a), phenolic components from group b), aldehyde components from group c) and metal compounds from group d) are reacted with one another at a temperature of from 100 to 260° C., preferably from 110 to 160° C., under a pressure of from 1 to 10 bar, preferably from 1.5 bar to 5 bar. The resultant mixture is then reacted with &agr;,&bgr;-ethylenically unsaturated carboxylic acids or their anhydrides from group e) in the temperature range from 100 to 260° C., preferably from 160° C. to 240° C.
In the synthesis process of the invention the progress of the reaction is judiciously monitored on the basis of the acid number and melting point of the reaction mixture. On reaching an acid number of 160-300 mg of KOH per g of resin, preferably 200-260 mg of KOH per g of resin, the reaction is termi
Metz Hans Joachim
Wallach Thomas
Weide Joachim
Clariant GmbH
Green Anthony
Hanf Scott E.
Jackson Susan S.
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