CH621569A5 - Process for the preparation of crystallisation-stable copper phthalocyanine pigments - Google Patents

Description

The invention relates to a process for the preparation of crystallization-stable copper phthalocyanine pigments as well as the pigments obtained according to this process.

It is known that dry grinding is frequently used during the packaging of phthalocyanines. It can be ground in the presence of a mineral substrate used as a grinding agent, and then eliminate this substrate. This is usually a water-soluble salt such as sodium chloride, sodium sulfate, aluminum sulfate, commonly used in the proportion of several parts of substrate for one part of phthalocyanine to be ground.

It is also known that phthalocyanines put in pigmentary form can, when they are in the medium of organic solvent, undergo with time important modifications of their coloring force and their nuance, as well as a phenomenon of flocculation.

Various means have been proposed to avoid this very troublesome development in practice.

For this purpose, phthalocyanines synthesized from phthalodinitrile were tested according to American patent No. 3,051,721 applied for on January 13, 1959 and French patent 1,271,406 applied for on October 19, 1960.

In the same perspective, weakly halogenated phthalocyanines have also been synthesized according to the American patent 3,024,247 filed on May 26, 1958, the German patent applications 1,200,981 requested on April 27, 1961 and 1,419,915 requested on October 31, 1961, and French patent 1,218,935 applied for on March 17, 1959.

These means have the disadvantage of not offering a solution for the stabilization of the phthalocyanines synthesized by other routes than those proposed, and, moreover, they do not always show satisfactory efficiency.

The incorporation of phthalocyanine to stabilize stabilizing compounds derived from phthalocyanine has also been used for the same purpose, as seen in French patents 2,114,243.2 114,244 and 2,114,245 applied for on November 10, 1970, as well as their first additions 73 18 490.73 18 491 and 73 18 492 filed on May 22, 1973, French patents 1 412 828 requested on October 28, 1964 and 1 332 175 requested on June 20, 1962, Japanese patent application 69/17026 filed on October 23, 1964, the German patent application

1,187,219 filed February 16, 1961.

These techniques, in particular those of French patents

2,114,243.2 114,244 and 2,114,245 and their first additions bring an appreciable improvement in the stability to solvents, the copper phthalocyanines treated according to these latter patents no longer give rise to any modification of their crystallographic form nor of their nuance, nor to appreciable increases in the size of their crystals. On the other hand, their crystallinity, their coloring strength, the viscosity of the pigmentary preparations based on organic solvents produced using these pigments continue to undergo appreciable variations over time despite these treatments.

The present invention aims to remedy these drawbacks.

It makes it possible to obtain phthalocyanine pigments in the form of both a paste in a solvent medium and a powder which not only maintains their crystallographic form, their shade and the dimensions of their crystals over time, but moreover presents in relation to the State of the art the significant progress of practically preserving their crystallinity over time, their color yield, the viscosity of the pigmentary preparations based on organic solvents produced using these pigments. In particular, the very good consistency of the crystallinity as a function of time and in a solvent medium is a characteristic result which can be obtained thanks to the invention.

The process for the preparation of crystallization-stable copper phthalocyanine pigments is defined in claim 1. The indication of the non-pigmentary nature of the phthalocyanine obtained after grinding and used for the second stage of the process is important.

621,569

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According to the new process, the coloring force is not developed by the grinding operation, but is practically developed only after grinding by treatment with the crystallizing solvent in the presence of the stabilizing product.

A "weakly pigmentary character" refers to pigments which show a coloring force less than the force required for the application considered (for example application in paint-emulsion).

As solvents are known to degrade the pigmentary character of phthalocyanines, it could not therefore be expected that, according to the new method, a non-pigmented or weakly pigmented phthalocyanine, brought into contact with a solvent, acquires precisely this pigmentary character.

This surprising result is obtained by the simultaneous presence of the phthalocyanine to be treated, the crystallizing solvent and the stabilizing compound. If the crystallizing solvent or the stabilizing compound had been omitted from this mixture, the final product would have been unusable.

The consistency over time of the properties of the pigment obtained according to the invention, both in coloring strength and in shade and for the rheological properties obtained in application is of great practical importance. The invention also makes it possible to confer on pigmentary phthalocyanines, of reddish blue shade or of β form, an improved speed of dispersion in organic media and a greater coloring force.

The subject of the invention is also the phthalocyanine pigments obtained by the new process as well as their use in a pigment composition.

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Example 1

In a bar mill, 96 parts of phthalocyanine form a (obtained by crystallization from sulfuric acid) are dry ground for 60 hours and without an inorganic substrate. The phthalocyanine thus obtained is not pigmentary. 3S

In 1000 parts of pyridine, 4 parts of stabilizer obtained according to Example 2 of French patent 2 114 243 are introduced, then 96 parts of ground phthalocyanine obtained previously. The mixture is brought to 80 ° C. and maintained at this temperature for 1 hour with stirring. The mixture is diluted with 1000 parts of water at 60 ° C, filtered, washed with water to remove the pyridine and the product is dried. You can also steam pyridine. A phthalocyanine pigment is obtained containing approximately 80% of form a and 20% of e with a beautiful blue-reddish shade, of excellent yield and stable to crystallization. This product is suitable for any pigment application.,

FIGS. 3 and 4 relate to the mixture of pigmentary copper phthalocyanine of form a and of 3% of the stabilizing compound according to example 2 of French patent 2 114 243. These figures 50 relate respectively to the X-ray powder diagram of this mixture before and after immersion for 2 hours in boiling xylene.

FIGS. 5 and 6 respectively represent the X-ray powder diagram of the pigment according to the present example, 55 before and after immersion for 2 hours in boiling xylene.

The comparison between FIGS. 3 and 4 shows that the pigment obtained according to the previous patent shows good stability to solvents, the crystallographic form is maintained. On the other hand, a large variation in the crystallinity 60 appears.

According to FIGS. 5 and 6, the pigment according to the invention shows improved stability to solvents compared to that of the aforementioned patent. Not only is the crystallographic form preserved, but moreover the crystallinity remains practically unchanged.

The variations in coloring strength and shade caused by the boiling xylene treatment are as follows:

If this treatment is subjected for 2 minutes to an unstabilized pigmentary phthalocyanine of form a, a reduction in coloring force of 200% is observed, and a greener product is collected.

If this treatment is subjected for 2 hours to the mixture of non-stabilized pigmentary phthalocyanine of form a and of stabilizing compound according to example 2 of French patent 2 114 243, there is an increase of 10% in the coloring force, and the product becomes more reddish.

If this same treatment is carried out for 2 hours with the pigment obtained according to the present example, it is found that the coloring strength as well as the shade remain perfectly unchanged. These comparisons of coloring strength and nuance were carried out in vinyl emulsion paint.

Variations of the same order are found after prolonged storage of the pigment in solvent medium in an ink or a paint, at ordinary temperature, this storage being able, according to the applications, to carry out durations going for example from a few weeks to a few months.

The speed of dispersion of the pigments in powder form is improved, compared to that of the corresponding industrial pigment according to the prior art, in applications relating to the coloring of plastics, inks, or paints. The corresponding industrial pigment is that which is used as a standard product in the application considered.

The coloring strength in nitrocellulose ink is 20% higher than that of the corresponding industrial pigment obtained according to the prior art, and the coloring strength in painting is 10% higher.

Example 2

In 400 parts of toluene, 4 parts of stabilizer obtained according to Example 2 of French Patent 2 114 243 are introduced, then 96 parts of ground non-pigmented phthalocyanine obtained according to Example 1. The mixture is brought to 100 ° C. and maintains it at this temperature for 1 hour with stirring. After filtration, a toluene paste of phthalocyanine pigment of blue-reddish shade (comprising approximately 60% of form a and 40% of form e), of high yield and stable to crystallization, is obtained. This product is suitable for engraving inks and solvent-based paints.

The speed of dispersion of the pigment obtained according to the present example in the form of a paste is significantly higher than that of the corresponding earlier industrial pigment.

Example 3

In 300 parts of trichlorethylene, 4 parts of stabilizer obtained according to example 2 of French patent 2 114 243 are introduced, then 96 parts of non-pigmented ground phthalocyanine obtained according to example 1. The mixture is brought to the boil and maintains it for 2 hours at the boiling temperature with stirring. 600 parts of white-sprit (containing less than 5% aromatics) are introduced. Trichlorethylene is distilled and, after filtration, a paste of phthalocyanine pigment of blue-reddish shade (comprising 80% of form a and 20% of form e) is obtained in a white spirit medium, of high yield and stable to crystallization. . This product is suitable for solvent painting.

The speed of dispersion of the pigment obtained according to the present example in the form of a paste is significantly higher than that of the corresponding earlier industrial pigment.

Example 4

In a bar mill, 96 parts of copper phthalocyanine in non-pigmented form are dry ground for 60 hours and without an inorganic substrate. A ground phthalocyanine of non-pigmentary form a is thus obtained.

In 500 parts of pyridine are introduced 4 parts of

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Indeed, if the grinding of crude phthalocyanine carried out without solvent or mineral substrate always leads to a non-pigmentary product, it is not the same for the grinding of phthalocyanine with a mineral substrate which if it is sufficiently prolonged leads to a product having a pigmentary character 5 (see Pigment Handbook, volume III, pages 30 and 31, “Nonazo organic pigments”).

In the process claimed in the present application, such grinding must be stopped as soon as this pigmentary character begins to develop (see below). It is only under these conditions that the advantages of the invention, such as stability to crystallization, speed of dispersion in improved organic media, greater coloring strength, can be achieved.

In the sense of the invention, the term “crystal-reading solvent” is defined as any solvent capable of causing profound modifications in the copper phthalocyanine of pigmentary form, free from phthalocyanine prepared from phthalic dinitrile, free from chlorine and free of stabilizing compound,

when this solvent at boiling point covers and permeates the pigment for 2 hours. These profound modifications include in particular a transformation of most or all of the pigment into a β-form pigment, and a significant increase in crystallinity, and are illustrated by Figures 1 and 2. These figures respectively represent the X-ray powder diagram of said copper phthalocyanine of form a before and after immersion in xylene. Xylene was chosen as a representative example of a crystallizing solvent. These figures have the angle "2 0" on the abscissa and the relative intensity of the diffracted 30 X radiation on the ordinate.

In FIG. 1, the location of the peaks is characteristic of the form a, the moderate height of the peaks shows a relatively low crystallinity.

FIG. 2 presents a very different aspect, the location of the peaks there is in fact characteristic of the β form and their much higher height, their fineness and their resolution (their separation) prove a clearly more marked state of crystallinity.

When the question arises of knowing whether or not a solvent is a crystallizing solvent in accordance with the invention, the definition and the criterion given above easily make it possible to answer it.

By way of nonlimiting examples, the following solvents are crystallizing solvents: benzene, toluene, xylene, chlor-ben-zene, nitrobenzene, aniline, pyridine, dimethylformamide, 45 dimethylsulfoxide, N-methylpyrrolidone, hexamethylphospho-rotriamide, morpholine, trichlorethylene, butyl acetate, a mixture of the solvents therebetween, an aqueous solution or an aqueous emulsion of these solvents, or a mixture of one or more of these solvents with non-crystallizing solvents. 50

The aqueous solutions or emulsions generally contain at least 40% and preferably at least 60% of solvent (composition which varies according to the solvent).

As an example of a non-crystallizing solvent, mention may be made of ethanol, acetone, aliphatic hydrocarbons, water. 55

When the treatment according to the new process is completed, it is possible to partially or entirely eliminate the crystallizing solvent from the suspension obtained at the end of said treatment by any means within the reach of those skilled in the art. Thus it is possible to obtain a pigment paste in a solvent medium, by separating the bulk of the solvent by filtration for example. It is possible to use this paste as it is in application. It is also possible to move the solvent (used for treatment) with another solvent suitable for another application, or to dry the pigment. 65

The concentration of ground phthalocyanine can be from 5 to 50% and more particularly from 10 to 40% by weight of the crystallizing solvent.

According to the invention, copper phthalocyanine is taken as crude phthalocyanine in one of the crystallographic forms a, ß, y or e (form e is sometimes also called form ô, X or R), or a mixture of these forms.

The crude phthalocyanine subjected to the new treatment may be a weakly halogenated phthalocyanine or synthesized from phthalic dinitrile. However, the invention applies with advantage to phthalocyanines prepared by other routes, for example from phthalic anhydride.

According to the process of the invention, pigments of shades between cyan (blue-greenish) and blue-reddish are obtained, depending on the nature and the crystallographic form of the starting crude phtaphthalocyanine and on the solvent used.

One obtains more particularly a pigment of form ß when one starts from crude phthalocyanine directly resulting from the synthesis, and a pigment of blue-reddish shade (of mixed form 80% a and 20% e for example), when one share of crude phthalocyanine with structure a which can be obtained by the acid route.

One can choose as stabilizing compound one of the compounds defined in accordance with French patents 2,114,243, 2,114,244.2 114,245 already mentioned.

The stabilizing compound can be introduced during or preferably after dry grinding.

The concentration of stabilizing compound is from 1 to 25% and preferably from 2 to 20% of the amount of phthalocyanine to be stabilized.

The temperature of the treatment with the crystallizing solvent is between the ordinary temperature and the boiling point of the solvent. It is most often at least 80%.

The duration of this treatment generally varies between a few minutes - 15 minutes for example - and ten hours and more particularly between half an hour and four hours.

Dry grinding of the new process makes it possible to obtain a phthalocyanine having the particle size required for pigmentary applications, but not necessarily having a pigmentary character, which depends not only on the particle size, but also on the crystallinity, on the form. and the degree of aggregation of the particles.

The moment when the dry grinding is interrupted can be determined by tests making it possible to verify the coloring force obtained according to the process of the invention in a well-defined type of application, for example in emulsion paint.

The X-ray diffraction spectrum of crushed samples also makes it possible to follow the development of the properties of the product under the effect of crushing. The 2 methods can advantageously be combined. It is possible according to the invention to carry out dry grinding of the crude phthalocyanine in the presence of mineral substrate.

However, while according to the prior art this grinding was generally continued until characteristic pigmentary properties are obtained, it is favorable according to the new method to stop the grinding as soon as a slightly pigmentary character appears. This can significantly reduce the duration of grinding.

However, according to a preferred form of the invention, dry grinding of the crude phthalocyanine is carried out without an inorganic substrate.

Grinding without an inorganic substrate has the advantage of greatly increasing the production capacity of the grinding installation, in addition to the fact that the operation of removing the substrate is avoided. This grinding can last for example from 50 to 70 hours.

At the end of this grinding, a phthalocyanine of non-pigmentary character (seen weakly pigmentary) is obtained.

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stabilizer obtained according to Example 2 of French patent 2 114 243 then 96 parts of ground phthalocyanine obtained previously. The mixture is brought to 100 ° C. and kept at this temperature for 2 hours with stirring. The pyridine is then removed by steam stripping and the product is dried. A phthalocyanine pigment of form a stable to crystallization is obtained.

Example 5

In a bar mill, 1096 parts of crude phthalocyanine form a (obtained by the acid route) are dry ground for 15 hours in the presence of 300 parts of mineral substrate (NaCl). The ground phthalocyanine thus obtained, after elimination of the mineral substrate, has only a low pigmentary yield. But,

after treatment with 1000 parts of pyridine in the presence of 4 15 parts of stabilization obtained according to example 2 of French patent 2 114 243, at 80 ° C for 1 hour with stirring and after dilution with water and washing to remove the pyridine and the inorganic substrate, a pigment of blue-reddish shade is obtained with very good pigmentary yield and stable to crystallization.

According to a variant, the mineral substrate is first removed from the mixture "ground phthalocyanine plus mineral substrate", then treated the ground phthalocyanine, free from mineral substrate, in the form of an aqueous paste or powder, with the same amounts of pyridine and stabilizer. This pigment is suitable for any pigmentary application.

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Ink I is a 10% copper phthalocyanine pigment β form ink obtained according to the present example. The grinding was carried out for 45 min in a ball mill.

Ink II is an ink containing 10% of industrial copper phthalocyanine pigment of ß form (this pigment comprises 6% of a derivative obtained according to example 2 of French patent 2 114 243) the grinding lasted 45 min at ball mill.

The measurements were carried out with a Brookfield viscometer at 100 rpm (with the “mobile No. 3”) at 20 ° C.

Among the reological properties, viscosity is one of the most important in the case of inks. Each type of printing corresponds to a type of ink having a certain viscosity and it is important that the rheological properties of an ink, and in particular the viscosity, vary as little as possible during its storage. From this point of view, the ink I has a stability clearly superior to that of the ink II.

The speed of dispersion of the pigment of the present example in the form of a powder is improved, compared with that of the previous corresponding industrial pigment, in applications for the coloring of plastics, inks or paints. -

The coloring strength of the pigment obtained according to the present example in nitrocellulose ink is 10% greater than that of the pigment.

Example 6

Raw copper phthalocyanine of form ß is dry milled in a ball mill for 56 hours without an inorganic substrate. The ground phthalocyanine thus obtained has a mixed crystallographic form (75% to 4-25% ß) and has no pigmentary power.

In 1000 parts of pyridine, 4 parts of stabilizer obtained according to Example 2 of French Patent 2 114 243 are introduced, then 96 parts of ground phthalocyanine obtained previously. The mixture is brought to 80 ° C. and maintained at this temperature for 1 hour with stirring. The mixture is diluted with 1000 parts of hot water at 60 ° C., filtered, washed with water to remove the pyridine and the product is dried. You can also steam pyridine. A phthalocyanine pigment is obtained entirely in β form (cyan shade) of high yield, stable to crystallization. This product is suitable for any pigment application.

Figure 7 shows the viscosity variations of two inks I and II during accelerated aging tests (storage at 50 ° C). In this figure, the abscissa expresses the duration of storage in days, and the ordinate the viscosity in centipoises.

The non-pigmented part of the two inks has the following composition:

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35

40

45

50

nitrocellulose ethanol ethyl acetate methyl ethyl ketone dibutylphthalate

: 15%: 26%: 26%: 26%: 7%

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Example 7

In 400 parts of toluene, 4 parts of stabilizer obtained according to example 2 of French patent 2 114 243 are introduced, then 96 parts of ground phthalocyanine in mixed form (75% a + 25% ß) obtained according to example 6. The mixture is brought to 100 ° C. and maintained at this temperature for 1 hour with stirring. After filtration, a toluene paste of phthalocyanine pigment is obtained, containing only 5% of form a, of high yield and stable to crystallization. This paste is suitable for engraving inks and solvent-based paints.

The speed of dispersion of the pigment obtained according to the present example in the form of a paste is much higher than that of the corresponding industrial pigment earlier.

Example 8

In 300 parts of trichlorethylene, 4 parts of stabilizer obtained according to example 2 of French patent 2114 243 are introduced, then 96 parts of ground phthalocyanine in mixed form (75% a + 25% ß) obtained according to example 6. brings the mixture to the boil and maintains it for 2 hours at the boiling temperature with stirring. 600 parts of white spirit (containing less than 5% aromatics) are introduced. Trichlorethylene is distilled and, after filtration, a phthalocyanine pigment paste of the β form is obtained, containing only 15% of form a in white spirit medium, of high yield and stable to crystallization. This paste is suitable for solvent paints.

The speed of dispersion of the pigment obtained according to the present example in the form of a paste is clearly higher than that of the corresponding previous industrial pigment.

2 sheets of drawings

Claims (10)

621,569 2 1. A process for the preparation of crystalline copper phthalocyanine pigment stable to crystallization, characterized in that a crude copper phthalocyanine is ground in the absence of a cirstallizing solvent and in avoiding the development of pigmentary character and that treats phthalocyanine resulting from grinding with a crystallizing solvent in the presence of a stabilizing compound derived from phthalocyanine. 2. Method according to claim 1, characterized in that the grinding is carried out dry. 10 3. Method according to claim 2, characterized in that the dry grinding of the crude phthalocyanine is carried out without mineral substrate. 4. Method according to claims 1,2 and 3, characterized in that the stabilizing compound is one of the following compounds: Pc- (CH2-X-A) n, withn = there 8, 11 with n = 1 to 8, or Pc CH2 - NH n with n = 1 to 4, 30 35 in which Pc represents the remainder of a phthalocyanine, X represents an oxygen or sulfur atom, A represents an aryl radical optionally substituted by alkyl groups, R represents hydrogen or alkyl groups. 5. Method according to claim 1, characterized in that one takes as crystallizing solvent one of the following compounds: benzene, toluene, xylene, chlorbenzene, nitrobenzene, aniline, pyridine, dimethylformamide, N-methylpyrrolidone, hexamethylphosphorotriamide , morpholine, trichlorethylene, butyl acetate, a mixture of these solvents with one another, an aqueous solution or an aqueous emulsion of these solvents, or a mixture of one or more of these solvents with non-crystallizing solvents. 6. Method according to claim 1, characterized in that the crude copper phthalocyanine is in one of the cirstallo-graphic forms a, ß, ô or s or a mixture of these forms. 50 7. Method according to claim 1, characterized in that the ground phthalocyanine is treated at a concentration of 5 to 50% and more particularly from 10 to 40% of the weight of the crystallizing solvent. 8. Method according to claims 1 and 3 to 7, characterized in. 55 that at the end of the treatment with the crystallizing solvent, the latter is eliminated in part or in whole. 9. Crystalline stable copper phthalocyanine pigment prepared by the process according to claim 1. 10. Use of the phatlocyanin pigment according to claim 9 in a pigment composition. 65