DK155610B - Process for the preparation of an organic pigment dispersion in an organic medium that is essentially free of water - Google Patents

Description

DK 155610 B

The present invention relates to a process for preparing an organic pigment dispersion in an organic medium and substantially free of water. The process according to the invention is characterized in that it is carried out directly on an aqueous slurry in which the organic pigment is prepared, this slurry containing 0.1-20% by weight of pigment, calculated on the slurry, mixed with the organic medium under vigorous agitation and in presence of a dispersant, after which the organic pigment dispersion comprising up to 50% water is isolated from the remaining aqueous phase, after which substantially all the water is removed from the aqueous pigment dispersion by contacting it with a set of surfaces having different affinity for water and the organic pigment dispersion, whereupon the water and the organic pigment dispersion which are substantially free of water are isolated separately.

The organic pigment dispersion prepared in accordance with the present invention can be used to produce inks and paints.

Transferring a suspended solid from a first liquid phase to a second liquid phase, the first and second liquid phases being mutually immiscible and the solid being insoluble in both liquid phases, is a well-known technique called "flushing" . (This transfer is then described by the verb "to flush"). Such a method is possible when the solid in question has a greater affinity for the second medium than for the first medium.

In the process of the invention, the first phase is water, optionally containing auxiliaries, and the second phase is the organic phase, optionally containing auxiliaries.

As used herein, the term "pigment" refers to the pigment per se plus any content of resins added during or after the chemical synthesis of the pigment. Especially in the case of yellow and red pigments, resins are added. The nature and nature of the resins are explained in detail below.

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It is known to transfer pigments from a press cake in which the pigment constitutes approx. 20-50%, by flushing to an organic phase. The flushing can be carried out by mixing the two phases (containing the solid), for example by means of a dough-knitter, a fast-moving agitator, a static agitator, etc. The resulting slurry of pigments in the organic phase usually comprises 40% pigment. The benefits of flushed pigments are mainly due to the fine structure of the pigments preserved in the flushed form.

The initial steps for producing dry or flushed pigment colors are identical. Chemical intermediates are reacted to form the pigment, which in most cases is isolated as an aqueous suspension (slurry) and filtered through a filter press or other filtration apparatus such as a centrifuge where the pigment solids are separated and a press cake or pulp is formed. While the original 15 slurry usually contains from 3 to 6 weight percent solids, the press cake contains from 20 to 50 weight percent pigment solids. The press cake is washed with water to remove soluble impurities (the cake is sometimes blown on the filter with air) and the press cake is removed from the filter for further processing.

The separation process performed by various filtration methods often results in undesirable compacting of the pigment particles.

The initial aqueous suspension of pigment can be prepared in various ways such as: (a) by precipitating a dye (a lacquer pigment) with a metal salt (barium chloride, calcium chloride, lead nitrate, etc.), (b) forming an insoluble pigment from a diazo coupling reaction, (c) by absorption of a dye on an inorganic hydrate (e.g., aluminum hydrate), or (d) by aqueous dilution of a dispersed or solvated pigment (e.g., phthalocyanine blue).

30 After the cake or pulp stage, dry and fluffy colors are produced in different ways. If dry colors are to be prepared, the cake is dried and pulverized. These later steps can lead to environmental problems caused by dry pigment dust.

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3 In the known methods, the press cake is transferred to the flushing equipment to flush the pigment. The organic medium is added in a predetermined amount and the mixture is made. When the organic medium replaces most of the water, the phases are separated and the aqueous phase is removed and discarded. The flushing process often has to be repeated to form a "dense" flushed mass, ie. a mass with a sufficiently high concentration of pigment in the organic medium.

A low water content of the flushed mass can be obtained by vacuum treatment.

DE-OS 23 60 093 (Deutsche Gold- und Silber-Scheideantalt), which is an application for supplementary patent to DE-PT 19 37 832, describes an improved process for the preparation of binder / pigment containing compositions in complete distribution or powder form. of pigment wherein the pigment concentrate having a content of 30-80% by weight, preferably 35-60% by weight, of a non-plastic binder which is solid at room temperature is dried and the dried mass optionally pulverized. DE-PT 19 37 832 discloses a flushing process in which an aqueous pigment mass is subjected to phase conversion by the addition of any solvent-containing pigment binder 20 and optionally using a flushing aid. The ratio of pigment, binder and optionally solvent is chosen such that a strong plastic pigment concentrate is obtained in a workable and deformation resistant consistency where the cohesive force exceeds the adhesive force. According to an example in DE-OS 23 60 25 093, which refers to DE-PT 19 37 832, the starting material for the flushing process (phase conversion) was an aqueous pigment mass containing 45% by weight ferrocyanide blue (berlin blue).

U.S. Patent No. 3,980,488 (Sherwin-Williams Company) discloses the flushing of partially ground organic pigment obtained in the form of a press cake 30 after filtering an aqueous slurry into an organic carrier in the presence of a rupture agent. According to the examples in this United States patent, the starting material for the flushing process was a press cake containing 40-50% by weight water.

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4 U.S. Patent No. 4,340,431 (BASF Wyandotte Corporation) discloses a method of transferring an organic pigment from an aqueous pulp of the pigment into a water-immiscible organic carrier by mixing the aqueous pulp and the carrier to most of the water. in the pulp is separated and the separation is enhanced by a petroleum-sulfonate additive and at least one additive which is sulfonated spermacet oil, sulfated spermacet oil, or mixtures thereof with the carrier and pigment. In all the examples, the pulp contained 24 weight percent pigment.

U.S. Patent No. 2,822,283 (Dehydag) discloses a method for transferring an inorganic pigment from an aqueous paste to a water-immiscible liquid in the presence of a small amount of a substituted cyclohexylamine. According to the Examples, the aqueous paste contained 30% by weight and 20% by weight of inorganic pigment, and the amount of 15-water immiscible liquid was of the same order of magnitude as the aqueous paste, which means that the ratio of the water-immiscible phase to the aqueous paste was 1: 0.7 and 1: 1.1, respectively.

French Patent No. 2,302,328 (ICI) discloses an aqueous emulsion 20 of pigment, alkyds, petroleum and detergent; the inorganic pigment is used in the dry state.

DE-OS 3,121,765 (BASF) discloses aqueous pigment pastes containing water, organic solvent, one or more pigments and a copolymer. According to the examples, the water content of the paste was 20-46.7% by weight.

DE A 2,732,710 discloses the flushing of pigments and it is stated therein that the flushing is carried out on press cakes of dyes directly as it appears in the production. The press cake in question is indicated in the examples to contain 20, 22, 50, 15 and 65% dye respectively.

The water contained in the flushed mass is removed as described by evaporation in vacuo.

DE A 3,143,678 also discloses a flushing process wherein

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5 secages containing 60-90% water are treated with a hydrophobic organic agent.

GB PS 1,342,746 (ICI) discloses dispersions of inorganic pigments for lacquers or toners in organic liquids in which one or more polyesters or a salt derived from a hydroxycarboxylic acid of the general formula have been dissolved

HO-X-COOH

wherein X represents a divalent saturated or unsaturated aliphatic radical containing at least 8 carbon atoms and wherein there are at least 4 carbon atoms between the hydroxy and carboxylic acid groups, or of a mixture of such hydroxycarboxylic acid and a carboxylic acid which does not contain hydroxy groups.

GB PS 1,373,660 (ICI) discloses similar dispersants, viz. the formula YCOZR wherein Z represents a divalent bridging group 15 linked to the carbonyl group via an oxygen or nitrogen atom, R represents a primary, secondary or tertiary amino group or a salt thereof with an acid or a quaternary ammonium al group, and Y represents the remainder of a polyester chain which together with the group -CO- is derived from a hydroxycarboxylic acid of the formula

HO-X-COOH

wherein X represents a divalent saturated or unsaturated aliphatic radical containing at least 8 carbon atoms and wherein there are at least 4 carbon atoms between the hydroxy and carboxylic acid groups, or of a mixture of such hydroxycarboxylic acid and a carboxylic acid which does not contain hydroxy groups.

In the disclosed printings there is no indication that flushing is performed on the aqueous phase per se in which the pigment is synthesized. When flushing has so far been performed, it has been performed on pastas, press cakes or "pulps", ie. on mixtures of pigments and aqueous phases in which the amount of pigment is much greater than is the case in the present invention.

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By proceeding with the method of the present invention, it is possible to proceed directly from the aqueous slurry in which the pigment is synthesized. This slurry usually contains 0.5-15% by weight, in particular 1-10% by weight, and especially 2-5% by weight, organic pigment. It is very advantageous to avoid the filtration which is a prerequisite for all the methods described in the prior art, as the filtration of the dye at this stage in the manufacturing process results in undesirable compacting of the pigment particles. By proceeding and starting the process according to the invention directly on the hot synthesis slurry, which is normally 60-90 ° C, the applied heat is also utilized, since the flushing runs smoothly even with the very small amounts of organic media in question. about, at this temperature. Separation of water and the organic medium containing the pigment, but also with up to 50% water incorporated, is easily accomplished by filtration under suction. Thus, after this operation, an organic pigment dispersion is obtained in an organic medium comprising up to 50% water. This water content is undesirable for many applications, which is why essentially all the water needs to be removed. This is done by the method of the invention by contacting the aqueous pigment dispersion with a set of surfaces of different affinity for water and for the organic pigment dispersion, respectively, whereby the water and the organic pigment dispersion which are substantially free of water are isolated separately. .

The organic pigment dispersion obtained after the flushing may have a water content of up to 50% by weight, especially up to 35% by weight, in particular up to 25% by weight, preferably up to 20% by weight and particularly preferably of no more than 15% by weight. After the isolation, the organic pigment dispersion is subjected to the further process step in which a substantial portion of the water present in the organic pigment dispersion is removed. Unsurprisingly, the water can be removed almost completely in this way.

The process according to the invention is particularly convenient in that it consists of a sequence of treatment steps, thereby obtaining in a economical and advantageous and very gentle manner a pigment dispersion with good application properties.

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A pigment concentrate with a high content of pigment is advantageous in that it is easily mixed by the user with other ink or paint ingredients, such as binders, thickening agents, etc. In the concentrate, the pigment is still a dispersion in the organic medium.

In order to obtain the best possible pigmentation of the ink, it is desirable to form a product with maximum pigment concentration without additional adjuvants which could limit the final application, and with a high degree of compatibility, so that a single product can be used in different systems. for example, for the manufacture of paints based on an aqueous emulsion latex, paints based on varnishes, etc., and in the printing ink industry.

When the pigment dispersions are to be used in the ink and paint industry, they are formulated with oily components and optionally auxiliary agents such as additional dispersants and solvents, binders, etc. in a manner known per se. The final formulation is usually made by the user who simply mixes the pigment dispersion of the invention with the other ingredients, usually in a mixing apparatus or on a series of rolls. The amount of pigment dispersion used depends on the final use, but is usually adjusted in such a way that the pigment solids constitute 10-25% by weight, especially 12-15% by weight of the final preparation ready for use in the printing industry.

In the process of the present invention, the organic pigment is selected from the group consisting of azo pigments such as diarylides and varnish pigments, phthalocyanines and other condensation pigments.

The ratio of the organic to the aqueous phase is between 1:20 and 1: 200, preferably between 1:30 and 1: 150, especially from 1:40 to 1: 100, based on parts by weight.

Surprisingly, a small amount of organic medium relative to the amount of water is capable of isolating the pigment particles which

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8 occurs in a very small amount in the aqueous phase. This is possible when the pigment is hydrophobic.

As the organic medium for use in the preparation of the organic pigment dispersion can be mentioned any organic medium normally used in the preparation of organic inks and paints.

Preferably, the organic medium is a low-polarity organic solvent, e.g., hydrocarbons.

The organic medium may also consist of one or more organic solvents selected from the group consisting of liquids having a boiling point of at least 80 ° C and in which the pigment is substantially insoluble.

A preferred organic medium comprises one or more solvents selected from the group consisting of aromatic and aliphatic, optionally halogenated hydrocarbons, esters, alcohols, ketones and ethers, and a particularly preferred medium comprises mineral oils having boiling points above 200 ° C.

Elevated temperatures, ie. temperatures above 20 ° C facilitate the transfer of the pigment from the aqueous to the organic phase.

It is usually not preferred to heat the mixture of aqueous and organic medium to a temperature above 95 ° C. Thus, the flushing method of the present invention can be carried out at a temperature of 30-95 ° C, especially at 50-90 ° C.

The dispersants used in the flushing process must be compatible with the organic medium in which the pigment is dispersed for final use. Dispersants enhance the phase transfer of the pigment from the aqueous to the organic medium. Therefore, the organic medium preferably contains one or more dispersing agents.

Dispersants for use in the process of the invention may be added to the pigment formed in the aqueous slurry.

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9 or to the organic medium with which the pigment is flushed or two or more dispersants may be used, one or more of which may be added to the aqueous slurry prior to the addition of the organic medium to which one or more dispersants may be added.

Dispersions with improved flowability are obtained when the dispersant is selected from the group consisting of resins, alkyds and dispersants having a molecular structure which allows them to be adhered to a selected pigment surface and further contains a solvent-soluble chain, so-called hyperdispersants. .

Particularly preferred dispersants are derivatives of a polyester derived from a hydroxycarboxylic acid of the formula HO-X-COOH, wherein X represents a divalent saturated or unsaturated radical containing at least 8 carbon atoms and where there are at least 4 carbon atoms between the hydroxy and 15 carboxylic acid groups. or of a mixture of such hydroxycarboxylic acid and a carboxylic acid which does not contain hydroxy groups. A derivative of a polyester may be the reaction product of an amine and the polyester, i.e. compounds containing an amide group. Advantageous derivatives of the above esters are amides and salts of the polyesters. Other useful dispersants are mixed amide / salt derivatives of polyesters.

In order to bind at least one of the components of the dispersant mixture or of the hyper-dispersants to the pigment particles, it is advantageous to use a synergist as coupling agent. A synergist 25 can be defined as a compound which can bind at least one of the components of the dispersant mixture to the pigment particles. A particularly preferred type of synergists are derivatives of the pigment. The synergist may form part of the dispersant mixture. The use of dispersants bonded to the pigment particle surface prevents unwanted flocculation of the pigment particles, so that later grinding of the pigment paste, if necessary, is facilitated and the final formation with, for example, varnish to produce ready-to-use ink is improved and the rheological properties of the ink are improved.

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In the preparation of most organic pigments and especially in the manufacture of yellow and red pigments, it is advantageous to add natural and / or synthetic, optionally modified resins (resins and raisins) to the aqueous reaction medium. In this way, the pigment particles can be coated with the resin. The coating can be performed by precipitating the resin on the pigment particles in the aqueous slurry. Such a coating will help counteract the agglomeration of the pigment particles. The precipitation can be made in different ways, depending on the chemical nature of the resin. One 10 precipitation method consists in the addition of an acid,, and. another method consists in the addition of a calcium ion-containing compound which causes the precipitation of a calcium salt by the resin.

Suitable resins for use in the manufacture of pigments are wood resins, hydrogenated wood resins, esters thereof, hydrocarbon resins and mixtures thereof. The resin content, i.e. the content of one or more resins / raisins, hereafter referred to only as "resin", may be of the same order of magnitude as the pigment content, which means that the resin may comprise up to 50% by weight of the dry matter in the final pigment dispersion.

The isolation of the organic pigment dispersion from the aqueous phase is usually done by filtration, optionally with suction.

After isolation from the aqueous phase, the resulting organic pigment dispersion contains pigment and optionally resin in an amount of 30-85% by weight, the other ingredients being the organic flushing medium and optionally dispersing agents and not more than 50% by weight water. The weight ratio of pigment (optionally containing resin) to organic medium is preferably between 30:70 and 85:15, especially between 40:60 and 60:40.

The dispersant is usually used in relatively large quantities, i.e.

30 up to an amount of 30% by weight, preferably up to 20% by weight, based on the pigment (optionally containing resin).

The organic pigment dispersion can be used per se in many applications. The largest consumption of flushed pigments takes place

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11 in the paint and printing industry where the pigments are mixed with solvents, binders and other additives (excipients), for example as described in the Examples.

The amount of water tolerated in the final product depends on the final use. If the pigment dispersion produced is to be used in a form in which water is undesirable, it is necessary to subject the pigment dispersion to a process step in which a substantial portion of the water content of the organic pigment dispersion is removed. In the prior art, water is removed from the flushed pigment by vacuum or by drying in an oven.

It has now been found that it is possible to remove the water from the pigment dispersion by contacting the dispersion with a set of surfaces having different affinity for water and the organic pigment dispersion, respectively. This contact operation will cause the aqueous and organic phase to separate, since the organic phase will tend to adhere more strongly to the surface than the aqueous phase. In a preferred embodiment of this water removal, the dispersion is contacted with a series of surfaces having different affinity for water and the organic medium, respectively, in which the organic pigment is dispersed. The two phases will then hang on the affected surfaces and can be removed from them, for example by means of a scraping device. The series of surfaces is advantageously a series of rollers, the surface of which has different affinity for water and the organic medium respectively. In this embodiment 25, the organic pigment dispersion is passed over a series of rollers as shown in the figure.

Examples of surfaces having different affinity for water and the organic medium include stainless steel and copper and exposed and unexposed offset plates, respectively. When the pigment dispersion is passed over a series of two or more rollers, one or more of which is made of copper and one or more is made of stainless steel, water will hang on the steel surface and can be removed from it, for example by means of a scraper, and the organic phase will hang on the copper surface and can be removed from it. In the same way

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12, a series of surfaces made of exposed and unexposed offset plates can be used.

This aspect of the present invention is described in more detail below with reference to the figure which shows an embodiment of an apparatus for use in the method of the invention.

The apparatus shows a pair of cooperating rollers consisting of a first roller 10 having an outer peripheral surface 11 and a second roller 12 having an outer peripheral surface 13. The peripheral surfaces 11 and 13 of the rollers are complementary formed so that their surfaces can be held 10 at a certain distance from each other. , when the rollers rotate about their respective axes so as to form a gap 14 between the rollers. In a preferred embodiment, the axes of the rollers 10 and 12 are substantially parallel, and the peripheral surfaces 11 and 13 of the rollers each define a circular cylindrical surface.

However, each of the peripheral surfaces 11 and 13 may define a rotating surface of any other type, provided that the rotating surfaces of the cooperating peripheral surfaces 11 and 13 are complementary. Alternatively, the axes of the rollers may form an acute angle, and each of the peripheral surfaces 11 and 20 may be conical or may have the shape of any other rotating surface.

The rollers 10 and 12 may, as shown by arrows 15 and 16, be driven in the opposite direction by conventional propellants (not shown) which may include sprockets, belt and / or chain drives. The drive means must be arranged to drive the rollers 10 and 12. The rollers can be operated at the same or at different peripheral speeds. The peripheral surfaces 11 and 13 of the rollers 10 and 12 are made of different material, or the two surfaces have different surface characteristics otherwise described in detail below.

The apparatus described above can be used to separate a component 17, e.g., water, from a viscous material or composition 18 comprising such component. The viscous material, which may be, for example, a mass of color pigment containing oil and water, can be passed to the upper side of the gap 14 defined between rollers 10 and 12.

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13 while the rollers are rotated as indicated by arrows 15 and 16. The viscous material or viscous mass 18 will then be rubbed out into a thin layer which is brought into intimate contact with the roller surfaces 11 and 13.

5 As mentioned above, the surface properties of the peripheral surface 11 are different from those of the peripheral surface 13. By way of example, the peripheral surface 11 of the roll 10 may be made of steel, while the peripheral surface 13 of the roll 12 is made of copper. In this case, the water component of the viscous mass 18 10 will tend to hang on the steel surface 11 rather than on the copper surface 13, while the oily pigment material will tend to hang on the copper surface 13 rather than on the steel surface 11. The water layer 19 hanging on the roller surface 11, can be removed from it by means of a stationary scraper or a stationary scraper 20 which is in contact with the roller surface 11. A layer 21 of pigment material 22 can be similarly removed from the roller surface 13 by a stationary scraper or a scraper blade 23 in contact with the roller surface 13.

It is to be understood that by means of an apparatus as described above, a component such as water or other liquid can be separated from a viscous mass which is fed continuously or at intervals to the upper part of the roller gap.

The invention is illustrated in more detail below in Examples 3,4, 5 and 6, in which the term "mineral oil" denotes a high boiling petroleum fraction at a boiling range of 250-290 ° C, usually called HBPF. Examples 1 and 2 describe the preparation of pigment "yellow 13", respectively without and with the addition of resin, Examples 7-10 are comparative examples of the preparation of finished pigments in known manner, and Example 11 describes a comparison of the 30 in different ways. color pigment of manufactured pigments.

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EXAMPLE 1

Preparation of Pigment Yellow 13 A. 52.4 g of 3,3'-dichlorobenzidine bis hydrochloride were slurried in 80 ml of water and 73.5 ml of 30% hydrochloric acid at 0 ° C with stirring for 2 hours. While keeping the temperature at 0 ° C, 400 ml of water and 22.5 g of sodium nitrite were added while stirring was continued for half an hour. Excess nitric acid was removed by sulfamic acid and water was added to a volume of 1200 ml. The solution was then filtered twice to remove impurities.

B. The filtrate from Step A was added over 2 hours at pH 4 and 20 ° C to a slurry of 66.6 g of acetoacet-2,4-dimethylanilide in a mixture of 1500 ml of water, 41 g of 30% hydrochloric acid and 19.2 g glacial acetic acid. The resulting slurry of pigment yellow 13 was heated to 80 ° C.

This slurry contained 96 g of pigment in 4.0 liters of water (= 2.4 wt. 15 percent pigment).

C. The slurry as prepared in step B was filtered, the filter cake was thoroughly washed with water and dried, and then the dry press cake was pulverized.

EXAMPLE 2 Preparation of a slurry of yellow pigment 13 with a resin

The tetrazo solution prepared in Step A of Example 1 was added over a period of 2 hours at pH 4 and 20 ° C to a slurry of 66.6 g of acetoacet-2,4-dimethylanilide in a mixture of 1500 ml of water, 41 g of 30% hydrochloric acid and 19.2 g glacial acetic acid. The resulting pigment slurry was heated to 80 ° C, 40 g of 28% sodium hydroxide solution was added and finally a solution of 57.3 g of hydrogenated wood resin was added in a mixture of 32.9 g of 28% sodium hydroxide and 480 ml of water. After standing overnight at 80-90 ° C, the pigment solution was acidified to pH 5.5.

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This slurry contained 149.1 g of pigment (including wood resin) in 5.8 liters of water (= 2.57% by weight pigment including resin).

EXAMPLE 3

Flushing a slurry of pigment yellow 13 containing wood resin 5 as dispersant and separation of water on rollers A. To 3.35 1 of the aqueous slurry prepared in Example 2 containing 86 g of pigment (including wood resin) was added 57.3 g of mineral oil. stirring with a high-speed stirrer at 50-60 ° C.

Over 2 minutes, the pigment-oil dispersion separated from the water, and it was then filtered on a Biichner funnel. Hot air was blown through the dispersion to remove excess surface water. The product contained 9% by weight water.

B. The pigment product obtained from step A was transferred onto a two-roll mill, one of the rollers being made of steel and the other of copper. As the organic phase had more affinity for the copper surface and water more affinity for the steel surface, the two phases separated.

The resulting pigment concentrate was organic and contained 60% by weight of pigment yellow 13 and 40% by weight of oil.

EXAMPLE 4

Flushing a slurry of pigment yellow 13 containing dispersants and subsequent separation of water on rollers A. To 3.35 l of the aqueous slurry prepared according to Example 2 containing 86 g of pigment (and wood resin) and 288 ml of a 25 aqueous slurry containing 6.9 g of Solsperse ™ 22000, 6.9 g

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Solsperse ™ 17000 and 7.7 g of mineral oil were added with 35.8 g of mineral oil with a high-speed stirrer at 50-60 ° C.

Over 1.5 minutes, the pigment oil dispersion separated from the water and then filtered on a Biichner funnel. Hot air was blown through the concentrate to remove excess surface water. This product contained 17% by weight water.

B. The pigment dispersion prepared under A was transferred to a two-roll mill, one of the rollers being made of steel and the other of copper, thereby separating the pigment concentrate from 10 remaining water.

The resulting organic pigment concentrate contained 60% by weight of pigment yellow 13 and 40% by weight of oil (including Solsperser).

EXAMPLE 5

Flushing of a slurry of pigment yellow 13 containing a dispersant and subsequent separation of water on rollers

To 3.58 liters of the aqueous slurry obtained according to Example 1, Step B containing 86 g of pigment and 288 ml of an aqueous suspension containing 6.9 g of Solsperse ™ 22000, 6.9 g of Solsperse ™ 17000 and 7.7 g of mineral oil were added. added 35.8 g of mineral oil, ie. a total of 43.5 g of mineral oil 20 with stirring with a high-speed stirrer at 50-60 ° C.

Over 12 minutes, the pigment oil dispersion separated from the water and then filtered on a Biichner funnel. Hot air was blown through the dispersion to remove excess surface water. The product contained 15% by weight water.

The pigment product produced was transferred to a two-roll mill, one of the rollers being made of steel and the other of copper, thereby separating the pigment concentrate from the remaining water.

17 DK 155610 B

The resulting pigment concentrate was organic and contained 60% by weight of pigment yellow 13 and 40% by weight of oil.

EXAMPLE 6

Flushing a slurry of pigment blue 15: 3 and subsequent separation of water on rollers A. To a slurry of 4.2 g of Solsperse ™ 5000 in 1.2 l of water at 80 ° C was added a slurry of 65 g. copper phthalocyanine in 2 1 water. 4.6 g of Solsperse ™ 17000 in 100 ml of water was added with stirring and stirring was continued for 45 minutes.

This slurry contained 73.8 g of pigment blue 15: 3 (comprising

Solsperse ™ 5000 and Solsperse ™ 17000) in 3.3 L of water (= 2.2% by weight pigment).

B. To the slurry prepared according to step A heated to 80-90 ° C was added 49.2 g of mineral oil with vigorous stirring. The pigment oil concentrate separated from the water within minutes and was filtered and washed thoroughly with water and dried to form a granulate containing 60% by weight of pigment blue 15: 3 (including dispersants) and 40% by weight of oil.

C. To the slurry prepared according to step A heated to 80-90 ° C, 49.2 g of mineral oil was added with vigorous stirring. The pigment-oil dispersion separated from the water within minutes and was filtered off and washed thoroughly with water. The pigment dispersion contained 35% by weight water.

The pigment dispersion was then transferred to a two-roll mill where one roller was made of steel and the other of copper, thereby separating the pigment concentrate from the remaining water.

The resulting pigment concentrate contained 60 wt% pigment blue 15: 3 (including dispersants) and 40 wt% oil.

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EXAMPLE 7

Flushing a slurry of pigment yellow 13 without resin and subsequent drying thereof

To 3.58 liters of the aqueous slurry 5 obtained in Example 1, containing 86 g of pigment, 57.3 g of mineral oil were added with stirring with a high-speed stirrer at 50-60 ° C.

The water separated from the pigment oil dispersion over 1.5 minutes, after which the dispersion was filtered on a Buchner funnel. Hot air was blown through the product to remove excess surface water. The product contained 69% by weight of water.

The aqueous product was dried in an oven at 65 ° C until a granulate containing 60% by weight of pigment yellow 13 and 40% by weight of oil was formed.

Example 8 15 Preparation of a pigment yellow 13 concentrate

The aqueous dispersion as prepared in Example 5 was dried in an oven at 65 ° G to form a granulate containing 60% by weight of pigment yellow 13 and 40% by weight of oil.

EXAMPLE 9 To 3.35 l of the aqueous slurry prepared according to Example 2 containing 86 g of pigment (and wood resin) was added 350 ml of an aqueous slurry containing 6.9 g of Solsperse1 * 22000, 6.9 g of Solsperse ™ 17000 and 1 4 g of mineral oil while stirring with a high-speed stirrer at 50-60 ° C.

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19 Within 2 minutes, the pigment oil dispersion separated from the water and then filtered on a Biichner funnel. Hot air was blown through the concentrate to remove excess surface water.

The aqueous product was dried in an oven at 65 ° C until a granulate containing 85% by weight of pigment yellow 13 and 15% by weight of oil (including Solsperser) was formed.

EXAMPLE 10

Flushing a slurry of pigment blue 15: 3 and subsequent drying thereof 10 A. A slurry of 65 g of copper phthalocyanine in 2 liters of water was heated to 80-90 ° C for 2 hours. This slurry contained 3.25% by weight of pigment blue 15: 3.

B. The slurry was filtered and washed thoroughly with water and the press cake dried.

To the slurry obtained in step A heated to 80-90 ° C was added 43.3 g of mineral oil with vigorous stirring. The pigment oil concentrate separated from the water within minutes and was filtered off, washed thoroughly with water and dried in an oven at 65 ° C to give a granulate containing 60% by weight pigment blue 15: 3 and 40% by weight oil.

EXAMPLE 11

Comparison of color strengths

Comparison of the products prepared according to Examples 7, 8, 3B, 4A, 9, 5, 4B, 10C, 6B and 6C For the preparation of offset inks, 22.3 g of concentrates

prepared according to Examples 7, 8, 3B, 4A, 5, 4B, 10C, 6B, respectively

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20 and 6C are each stirred with 66.8 g of offset quiek set varnish and 10.9 g of mineral oil with a high-speed stirrer.

For the preparation of offset printing ink, 15.7 g of concentrate prepared according to Example 9 was stirred with 66.8 g of offset quick-set varnish and 17.5 g of mineral oil with a high-speed stirrer.

The degree of dispersion was assessed partly by measuring the "grinding value" on a grindometer (0-25 μ) and partly by examining the dispersions using a microscope (400x magnification).

Depending on the initial degree of dispersion, the resulting inks are passed once through a three-roller mill under light pressure. In some examples, the degree of dispersion was so good after prior dispersion with a high-speed stirrer that passage across the three-roll mill was unnecessary.

In comparison, offset inks were prepared from basic pigments of Examples 1C and 10B, i.e. 13.3 g of pigment was stirred with 86.7 g of offset quick-set varnish with a high-speed stirrer. Finally, these inks were sent twice through the three-roll mill.

All the inks were set to the same plastic viscosity, 14-15 Pa.s., measured on a Laray Bar Viscometer with a shear rate of D = 800 sec.

To assess the evolution of color in each example and for comparison with the base pigment of Examples 1C and 10B, quantitative printing was made on an I.G.T Printability Tester with a film thickness of 1 micron.

25 Inks made from concentrates prepared according to Example 7 showed the same property in color development as inks made from base pigment (Example 1C), whereas concentrates made according to Example 8 gave greater color strength. In both cases, it was necessary to allow the colors to pass through the three-roll mill once under light pressure. The same was true for inks made according to Examples 3, 9 and 5, whereas

Claims (10)

A process for preparing an organic pigment dispersion in an organic medium and substantially free of water, characterized in that an aqueous slurry of the organic pigment containing 0.1-20% by weight of pigment, based on the slurry, is an aqueous slurry. that obtained by synthesis of the pigment in the presence of a dispersant is mixed with the organic medium under vigorous agitation, and the organic pigment dispersion comprising up to 50% by weight of water is isolated from the remaining aqueous phase, after which substantially all the water is removed from it. aqueous organic pigment dispersion by contacting it with a set of surfaces having different affinity for water and the organic pigment dispersion, respectively, after which the water and the organic pigment dispersion which are substantially free of water are isolated separately. Process according to claim 1, characterized in that the aqueous organic pigment dispersion comprises up to 15% by weight water. Process according to claim 1, characterized in that the organic pigment constitutes 0.5-15% by weight, especially 1-10% by weight, of the aqueous slurry. Process according to Claim 1, 30, characterized in that the organic medium is an organic DK 155610B medium which is normally used for the production of organic inks and paints. Process according to claim 4, characterized in that the organic medium is selected from the group consisting of aromatic and aliphatic, optionally halogenated hydrocarbons, esters, alcohols, ketones, ethers and mixtures thereof. 6. A process according to claim 1, characterized in that the dispersant is one or more agents selected from the group consisting of resins, alkyds and dispersants having a molecular structure which allows them to adhere to a selected pigment surface. and further contains a solvent-soluble chain, so-called hyper-dispersants. Process according to claim 1, characterized in that the aqueous slurry contains one or more resins in an amount of up to 50% by weight based on the dry matter in the organic pigment dispersion. Process according to claim 1, characterized in that the resulting organic pigment dispersion comprises pigment and optionally resin in an amount of 30-85% by weight. Method according to claim 1, characterized in that the set of surfaces with different affinity for water and the organic pigment dispersion, respectively, is formed as a set of rollers. Method according to claim 9, characterized in that the surface of the rollers is made of steel and copper respectively.