WO2003006557A1

WO2003006557A1 - Thermoplastic fluorescent pigment

Info

Publication number: WO2003006557A1
Application number: PCT/IB2002/002682
Authority: WO
Inventors: Bansi Lal Kaul; Jean-Christophe Graciet; Nikolay N. Barashkov; Thomas C. Molloy; Ronghua Liu
Original assignee: Clariant International Ltd.; Clariant Finance (Bvi) Limited
Priority date: 2001-07-09
Filing date: 2002-07-08
Publication date: 2003-01-23
Also published as: EP1406973A1; GB0116677D0; CN1524112A; JP2004534142A; KR20040018436A

Abstract

The invention relates to a thermoplastic fluorescent pigment obtained by the condensation of a diisocyanate prepolymer and an aliphatic diamine, a cycloaliphatic diamine or a mixture of a diamine and a polyol in the presence of a fluorescent dye, wherein the prepolymer is obtained by the reaction of an aromatic sulfonamide with an excess of aliphatic, cycloaliphatic and/or or aromatic diisocyanate, and wherein the molar excess of diisocyanate in the prepolymer equals the molar amount of the aliphatic diamine, the cycloaliphatic diamine or the mixture of a diamine and polyol present in the condensation suspension.

Description

THERMOPLASTIC FLUORESCENT PIGMENT

The present invention provides thermoplastic fluorescent pigments having improved solvent resistance which are suitable for coloring a variety of materials including plastics, particularly polyolefins, as well as paints, inks and textiles.

BACKGROUND

Processes for producing thermoplastic fluorescent pigments by reacting dicarboxylic acids and difunctional alcohols, diamines and/or alkanolamines have been known in the past. US 3,922,232 (Schein) discloses as a matrix for fluorescent dyestuff certain resinous precondensates derived from a polyfunctional acid component and a polyhydroxy compound. However, this process possesses a number of shortcomings, since the softening temperatures of the obtained thermoplastic fluorescent pigments do not exceed 150°C. Further, they are soluble in a relatively large number of organic solvents and therefore are limited in their applications.

Further, US 6,103,006 (DiPietro) discloses thermoplastic fluorescent pigments wherein a fluorescent dye is reacted into, and covalently bound to a polymer backbone. The polymer backbone is described as preferably being a polyamide or polyamidester.

A number of approaches to increase the softening temperatures and the solvent resistance of thermoplastic fluorescent pigments have been disclosed. One approach entails the polyaddition reaction of diisocyanates with sulfonamide and polyols disclosed in US 3,741 ,907 (Beyerlin). The obtained thermoplastic fluorescent pigments have a softening temperature between 155 and 270°C and are insoluble or practically insoluble in the solvents usually employed for organic coating compositions and inks. The polyaddition reaction is carried out in bulk at temperatures between 100 and 250°C, preferably between 150 and 200°C. The disadvantage of this process is that the polyaddition reaction is exothermic and the temperature of the reaction mixture can rise spontaneously, easily exceeding the level of thermodegradation of fluorescent dyes dispersed in the polymerization mixture prior to formation of the resin.

US 5,795,379 (Schwenk et al) discloses the reaction of an oligomerized polyisocyanate with a mixture of polyfunctional compounds having active hydrogen in presence of a dye to form a thermoplastic pigment. The formation of the resin is carried out in bulk, e.g. in reaction extrusion, at a temperature higher than 200°C. The preferred oligomerized polyisocyanate is a trimerized isophorone diisocyanate. The preferred polyfunctional compounds are amine, amide or alcohol or carboxylic, sulfonic or phosphoric acid. The disadvantage of this bulk process is that the polyaddition reaction is exothermic and the temperature of the reaction mixture can rise spontaneously, easily exceeding the level of thermodegradation of fluorescent dyes dispersed in the polymerization mixture prior to formation of the resin. Another approach to increase the softening temperatures and the solvent resistance of thermoplastic fluorescent pigments includes a two step process as described in US 5,714,090 (Waters et al). On the first stage a prepolymer in an aqueous dispersion is formed by reacting an excess of diamine or polyol with diisocyanates. On the second stage the dispersion is cured with an anhydride, like phthalic anhydride, and metal oxide, like magnesium oxide. The thermoset fluorescent pigments have a degradation point of less than 250°C. The disadvantage of this process is that the fluorescent dyes have limited solubility in polyureas or polyurethanes and therefore the pigments formed possess relatively weak color.

SUMMARY OF THE INVENTION

The present invention provides for novel thermoplastic fluorescent pigments with a softening temperature higher than 180°C and an excellent solvent resistance. The pigments according to the invention are prepared by a two stage process. The first stage comprises the formation of a liquid colored oligomer (prepolymer) by reacting an excess of diisocyanates with sulfonamide and dyeing the prepolymer. On the second stage a dispersion of the dyed prepolymer in an aqueous solution of protective colloid is solidified with an equimolar amount of diamine or a mixture of diamine and polyol, yielding the condensation polymers with polyurea or copoly(urea)urethane structure, or without any diamine or polyol, in the latter case, prepolymer is solidified by water, yielding polyurea through an unstable carbamic acid intermediate that dissociates into an amine and carbon dioxide. The obtained thermoplastic fluorescent pigments are insoluble or practically insoluble in most organic solvents with a softening temperature higher than 180 °. They either consist of non-spherical particles having a broad particle size distribution and irregular shape (if no surfactants are used) or they consist of substantially spherical microparticles of uniform size from 1 to 5 microns (if one or several surfactants are used).

The invention further provides for a method of producing such pigment comprising the steps of A) reacting a member selected from the group consisting of aliphatic, cycloaliphatic and aromatic diisocyanate and mixtures thereof with aromatic sulfonamide in the presence of a catalyst,

B) dyeing the prepolymer of A with a fluorescent dye or a combination of fluorescent dyes,

C) introducing the dyed prepolymer of B into an aqueous solution of protective colloid which optionally may comprise a surfactant,

D) reacting the suspension of C) with a member from the group consisting of aliphatic or cycloaliphatic diamine or a mixture of aliphatic or cycloaliphatic diamine with polyols or with water in the presence of a catalyst,

E) separating the hardened resin from the suspension followed by drying and deaggregating the dried hardened resin.

DETAILED DESCRIPTION OF THE INVENTION The solvent resistant pigments of the invention can be obtained in the following manner:

A member selected from the group consisting of aliphatic, cycloaliphatic and aromatic diisocyanate and mixtures thereof is reacted with aromatic sulfonamide in the presence of a catalyst at temperatures from 40 to 90°C, preferably from 50 to 60°C. The preferred catalyst for step A is triethylamine and is present in an amount from 1 to 5% by weight, most preferably from 2 to 4% by weight. The mixture of aliphatic and/or cycloaliphatic diisocyanates with aromatic diisocyanate preferably contains 10 to 50% by weight of aromatic diisocyanate. For each mol of diisocyanate, 0.1 to 0.4 moles, preferably 0.2 to 0.3 moles of aromatic sulfonamide is present in the reaction mixture. Representatives of aliphatic and cycloaliphatic diisocyanates include, for example, 1 ,4- tetramethylene diisocyanate, 1 ,6-hexamethylenediisocyanate, trimethylhexamethylene- diisocyanate, 3-isocyanatomethyl-3,5,5-thmethylcyclohexyl isocyanate (isophorone diisocyanate) and 4,4'-diisocyanato-dicyclohexylmethane. Representatives of aromatic diisocyanates include, for example, phenylene-1 ,4-diisocyanate, 2,4- and 2,6-tolylene diisocyanate and their technical mixture, naphthylene-1 ,5-diisocyanate, 3,3'-bitolylene- 4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane- 4,4'-diisocyanate, metaphenylene diisocyanate, 2,4-tolylene diisocyanate dimer and dianisidine diisocyanate. Representatives of aromatic sulfonamides include, for example, benzenesulfonamide, p- and o-toluenesulfonamide and their technical mixtures, naphtalene-1 -sulfonamide, naphtalene-2-sulfonamide, m-nitrobenzenesulfoamide and p-chlorobenzenesulfon- amide.

The fluorescent dyes are selected from the group consisting of a) water-soluble fluorescent dyes, b) oil-soluble (water-insoluble) fluorescent dyes, c) moderately fluorescent polymer-soluble dyes and d) mixtures of a) and/or b) with c) in a ratio of 10- 90% by weight of a) and/or b) and 90-10% by weight of c).

Typical representatives of water-soluble fluorescent dyes are rhodamines, fluoresceines and some coumarins, containing ionic groups in their structure, like Basic Yellow 40. The typical representatives of oil-soluble (water-insoluble) fluorescent dyes are coumarins, like Blankophor SOL, Solvent Yellow 135 or naphthalimides. Moderately fluorescent polymer-soluble dyes are for example heterocyclic compounds with structures (I) to (V) having reactive amino- or hydroxy-groups.

wherein

X is oxygen or NR₂' with R₂' independently being defined as R₂; R is is hydrogen, halogen, -NR₂R₃, R₃-O- or R₃-S-,

R₂ is hydrogen, Cι_-6alkyl, C₆.ιoaryl, (Ce-ioJaryKd-e kyl or (Cι-5)alkyl-(C₆. ιo)aryl, the alkyl and/or aryl radicals being substituted by hydroxyl, d-

₆alkoxy, C₆-ιoaryloxy or halogen; and R₃ is Ci-βalkyl, C₆-ioaryl, (C₆.₁₀)aryl-(Cι-6)alkyl or (Cι.6)alkyl-(C₆-ιo)aryl, the alkyl and/or aryl radicals being substituted by hydroxyl, d-βalkoxy, C₆-ιoaryloxy or halogen; R, and R₅ independently being defined as R₂;

Y is sulphur, oxygen or -NR₂" with R₂" independently being defined as R₂;and n, m and p are 0-12.

Preferred dyes are Basic Yellow 40, Solvent Yellow 160, Basonyl Red 485 and Basonyl Red 560, as well as dye compounds according to formula (I) and (III), wherein X is oxygen or NR₂' with R₂ ^* being hydrogen or methyl. R_T is hydrogen, Y is sulphur and n,m and p are 2 to 6, preferably 2 or 3.

The fluorescent dyes are added in an amount of 1 to 5% by weight, preferably 2 to 4% by weight and most preferably of around 3% by weight.

For preparing the aqueous solution of protective colloid of step C and D, 1 to 5% by weight, preferably 2 to 4% by weight and most preferably around 3% by weight (based on the weight of the dyed prepolymer of B) of water soluble polymer are mixed with water to form the protective colloid. Optionally 1 to 3% by weight of surfactant, either non-ionic surfactants or a mixture of ionic and non-ionic surfactants are added. Typical water-soluble polymers to form the protective colloid are hydroxyethylcellulose, sodium salt of carboxymethylcellulose, methylcellulose, ethylcellulose, polyvinyl alcohol, and water-soluble polymers and copolymers of acrylic or methacrylic acid. Appropriate non-ionic surfactants are Solsperse 41090 (Phosphated alkoxylated polymer from ZENECA Specialties), Surfinol CT-111 (2,4,7,9-tetramethyl-5-decyn-4,7- diol from Air Product & Chemicals, Inc.) and Triton CF-10 (Alkylarylpolyether from Union Carbide). Examples of a mixture of non-ionic and ionic surfactants are the compositions of the above mentioned non-ionic surfactants and potassium tripolyphosphate, sodium lauryl sulfate or Surfinol CT-131 (from Air Product & Chemical, Inc.) in a ratio from 1 :1 up to 3:1 of non-ionic to ionic surfactant.

Further, for each mol of diisocyanate, 0.6 to 0.9 moles of aliphatic diamine, cycloaliphatic diamine or a mixture of aliphatic or cycloaliphatic diamine with polyols are added. The molar amount of diamine (or diamine and polyol) plus the molar amount of sulfonamide introduced in the prepolymer in step A has to be equal to the molar amount of diisocyanate introduced in the prepolymer of step A. In the absence of diamine or polyol, isocyanate groups in the prepolymer will react with excess of water to form polyurea through an unstable carbamic acid intermediate that dissociates into an amine and carbon dioxide.

Representatives of aliphatic and cycloaliphatic diamines include, for example, 1 ,2- ethylenediamine, 1 ,4-tetramethylene diamine, 1 ,6-hexamethylene diamine, trimethyl- hexamethylene diamine, 1 ,4-diaminocyclohexane, isophorone diamine, hydrogenated 4,4'-diaminodiphenylmethane.

The mixture of diamines and polyols contains 90 to 10% by weight of diamines and 10 to 90% by weight of polyols.

Representatives of polyols include, for example, ethylene glycol, propylene glycol, 1 ,3- propanediol, 1 ,4-butanediol, 1,5-pentanediol, 1 ,6-hexanediol, 1 ,4-bis-(hydroxymethyl)- cyclohexane, bisphenol A, trimethylolpropane, glycerine, pentaerythritol and dipentaerythritol.

The dyed prepolymer of B is added to the prepared aqueous solution of protective colloid comprising a catalyst and the aliphatic diamine, cycloaliphatic diamine or the mixture of aliphatic or cycloaliphatic diamine with polyols. The solution is reacted at temperatures from 40 to 90°C, preferably from 70 to 80°C. The preferred catalyst for step D is triethylamine and is present in an amount from 1 to 5% by weight, most preferably from 2 to 4% by weight. Preferably the dyed liquid prepolymer is slowly added under agitation with high shear (e.g. 6000-7000 rpm with a Homomixer) to obtain the insoluble pigment having a high softening temperature. The reaction mixture is kept at the preferred temperature for 0.5 to 2 hours under continuing agitation (e.g. with a Homomixer).

If the solidification of the prepolymer is carried out in a short time of less than 0.5 hours or with no agitation, partial or total aggregation of the pigment particles is observed.

The hardened resin is separated from the suspension, e.g. by filtration, dryed, preferably at a temperature ranging from 100 to 120°C for about 2 to 10 hours and deaggregated, e.g by grinding the hardened resin to the desired particle size by means of a pin mill or jet mill. The preferred pigment particle size is less than 10 microns, most preferred from 1 to 5 microns.

The thermoplastic fluorescent pigment obtained by the process of the invention demonstrate extremely superior dispersibility, heat resistance and resistance to solvents. Hence, the vividness and staining power of the dye used can be manifested effectively.

The thermoplastic fluorescent pigment according to the invention are suitable for the mass pigmentation of substrates including synthetic polymers, synthetic resins and regenerated fibers optionally in the presence of solvents. These substrates more particularly include oil, water and solvent based surface coatings, polyester spinning melts, polyethylene, polystyrene and polyvinyl chloride melts, polymethacrylate and polymethylmethacrylate melts, polyuethane masses, rubber and synthetic leather. Furthermore, the pigments can be used in the manufacture of printing inks, for the mass coloration of paper and for coating and printing textiles.

The thermoplastic fluorescent pigment according to the invention are also suitable as colorants in electrophotographic toners and developers, such as one- or two- component powder toners (also called one- or two-component developers), magnetic toners, liquid toners, polymerization toners and specialty toners.

Typical toner binders are addition polymerization, polyaddition and polycondensation resins, such as styrene, styrene-acrylate, styrene-butadiene, acrylate, polyester and phenol-epoxy resins, polysulphones, polyurethanes, individually or in combination, and also polyethylene and polypropylene, which may comprise further constituents, such as charge control agents, waxes or flow assistants, or may be modified subsequently with these additives. The thermoplastic fluorescent pigment according to the invention are suitable, furthermore, as colorants in powders and powder coating materials, especially in triboelectrically or electrokinetically sprayable powder coating materials which are used for the surface coating of articles made, for example, from metal, wood, plastic, glass, ceramic, concrete, textile material, paper or rubber.

Powder coating resins that are typically employed are epoxy resins, carboxyl- and hydroxyl-containing polyester resins, polyurethane resins and acrylic resins, together with customary hardeners. Combinations of resins are also used. For example, epoxy resins are frequently employed in combination with carboxyl- and hydroxyl-containing polyester resins. Typical hardener components (as a function of the resin system) are, for example, acid anhydrides, imidazoles and also dicyanodiamide and its derivatives, blocked isocyanates, bisacylurethanes, phenolic and melamine resins, triglycidyl isocyanurates, oxazolines and dicarboxylic acids.

In addition, the thermoplastic fluorescent pigment according to the invention are suitable as colorants in ink-jet inks.

The following examples will serve to more fully illustrate the invention. Unless otherwise specified, the parts and percentages used in the examples are on a weight to weight basis.

EXAMPLE 1

A 4-necked flask equipped with a stirrer, a reflux condenser and a thermocouple was charged with 200 parts of isophorone diisocyanate, 38.5 parts of para- toluenesulfonamide and 10 parts of triethylamine. While agitating this mixture, its temperature was raised to 70°C, and the reaction was carried out for 1.5 hours to obtain a liquid prepolymer. The prepolymer thus obtained is mixed with 7.2 parts of fluorescent dye Solvent Yellow 160 at temperature of 50-60°C.

Separately, an aqueous protective colloid solution was prepared by dissolving in 2000 parts of water 6.0 parts of acrylamide/sodium acrylate copolymer (CYANAMER 370 produced by Cytec Industries Inc.). After raising the temperature of this aqueous solution to 70°C, 10 parts of triethylamine were added, and the mixture was stirred at 7000 rpm with a high speed agitator. While this aqueous solution of protective colloid was being stirred, 120 parts of isophorone diamine were added and then the liquid prepolymer was slowly introduced to the protective colloid solution within 0.5 hour to obtain a bright yellow suspension. Next, the suspension was intensly stirred for 1 hour at 80°C.

The obtained product was separated from the suspension by filtration, and the filter cake was dried at a temperature of 100°C followed by heating for 3 hours at a temperature of 120°C to obtain 330 parts of aggregates of the pigment which were deagglomerated by means of a jet mill.

Properties:

The obtained product was examined with a scanning electron microscope. It was found that the obtained product consists of discrete, irregular shaped particles with substantially broad particle size distribution. With a Beckman-Coulter LS230 Particle Size Analyzer the mean particle size of the particles was determined to be 4.3 microns. The yellow fluorescent powder demonstrates extremely good dispersibility, a high softening point (195-198°C), good heat resistance and resistance to solvents.

The obtained product was further tested in the following bleed test: 25 parts of vinyl composition CPI Freedom Plus A-1-B-02 Ultra Soft Base and 25 parts of Diisononil phtalate from Exxon were mixed carefully with 5.6 parts of the pigment. The composition was placed in an aluminum dish and heated in the oven at 150 °C for 5 minutes. After cooling down to room temperature the pigmented plasticized vinyl swatch was placed in contact with a sheet of white plasticized vinyl and heated in the oven at 43°C for 24 hours. The observed color migration is significantly less than with conventional melamine-formaldehyde-sulfonamide pigments.

EXAMPLE 2

A 4-necked flask equipped with a stirrer, a reflux condenser and a thermocouple was charged with 200 parts of isophorone diisocyanate, 38.5 parts of para- toluenesulfonamide and 10 parts of triethylamine. While agitating this mixture, its temperature was raised to 70°C, and its reaction was carried out for 1.5 hours to obtain a liquid prepolymer. The reactional solution was treated with 5.0 parts of oxalic acid in order to neutralize the excess of triethylamine. The prepolymer thus obtained is mixed with 7.2 parts of fluorescent dye Basic Yellow 40 at temperature 50-60°C.

Separately, an aqueous protective colloid solution was prepared by dissolving in 2000 parts of water 6.0 parts of acrylamide/sodium acrylate copolymer (CYANAMER P-21 produced by Cytec Industries Inc.). After raising the temperature of this aqueous solution to 70°C, and the mixture was stirred at 7000 rpm with a high speed agitator. While this aqueous solution of protective colloid was being stirred, 120 parts of isophorone diamine and 204 parts of 36% solution of HCI were added. Then the liquid prepolymer was slowly introduced to the protective colloid solution within 0.5 hour to obtain a bright yellow suspension. The suspension was held for 2.5 hours at 80°C with an intense stirring.

The obtained product was separated from the suspension by filtration, and the filter cake was dried at a temperature of 100°C followed by heating for 3 hours at a temperature of 120°C to obtain 340 parts of aggregates of the pigment.

Properties:

The mean particle size was 3.9 microns and the softening temperature was 197-201 °C. The obtained product exhibited excellent dispersibility, heat resistance and resistance to solvents. The bleed test with plasticized polyvinylchloride as in Example 1 shows significantly less color migration than with conventional melamine-formaldehyde- sulfonamide pigments.

EXAMPLE 3

A 4-necked flask equipped with a stirrer, a reflux condenser and a thermocouple was charged with 150 parts of isophorone diisocyanate, 50 parts of 2,4-toluene diisocyanate, 38.5 parts of para-toluenesulfonamide and 10 parts of triethylamine. While agitating this mixture, its temperature was raised to 70°C, and its reaction was carried out for 1.5 hours to obtain a liquid prepolymer. The prepolymer thus obtained is mixed with 0.80 parts of Basonyl Red 485 and 4.3 parts of Basonyl Red 560 at a temperature of 50-60°C. Separately, an aqueous protective colloid solution in 2000 parts of water was prepared by operating as in Example 1. After raising the temperature of this aqueous solution to 70°C, 10 parts of triethylamine was added and the mixture was stirred at 7000 rpm with a high speed agitator. While this aqueous solution of protective colloid was being stirred, the mixture of 52.8 parts of isophorone diamine and 85.6 parts of pentaerythritol was added and then the liquid prepolymer was slowly introduced to the protective colloid solution within 0.5 hour to obtain a bright pink suspension. The suspension was held for 2.5 hour at 80°C with an intense stirring.

The obtained product was separated from the suspension by filtration, and the filter cake was dried at a temperature of 100°C followed by heating for 3 hours at a temperature of 120°C to obtain 310 parts of aggregates of the pigment.

Properties: The mean particle size was 4.6 microns and the softening temperature was 203-206°C. The obtained product exhibited excellent dispersibility, heat resistance and resistance to solvents. The bleed test with plasticized polyvinylchloride as in Example 1 shows significantly less color migration than with conventional melamine-formaldehyde- sulfonamide pigments.

EXAMPLE 4

238.5 parts of prepolymer are prepared by operating as in Example 1 and mixed with 4.70 parts of fluorescent dye Solvent Yellow 160, 3.70 parts of Basonyl Red 485 and 4.30 parts of Basonyl Red 560 at temperature 40-50°C.

Separately , an aqueous protective colloid solution was prepared by dissolving in 2000 parts of water 8.0 parts of CYANAMER A-370, 8.0 parts of Solsperse 41090 (Phosphated alkoxylated polymer from ZENECA Specialties), and 4.0 parts of SURFINOL CT-131 (produced by Air Product & Chemicals, Inc.). After raising the temperature of this aqueous solution to 70°C, 10 parts of triethylamine were added and the mixture was stirred at 7000 rpm with a high speed agitator. While this aqueous solution of protective colloid was being stirred, 120 parts of isophorone diamine were added and then the liquid prepolymer was slowly introduced to the protective colloid solution within 0.5 hour to obtain a bright red suspension. The suspension was held at 80°C for 1.5 hours with intense stirring. The finely divided solidified mostly spherical pigment particles were separated from the stable suspension by filtration through Whatman filter paper No. 4.

Properties:

The obtained product was examined with a scanning electron microscope. It was found that the obtained product consists of discrete, mostly sherical shaped particles. With a Beckman-Coulter LS230 Particle Size Analyzer the mean particle size of the particles was determined to be 4.0 microns. The softening temperature was 205-208°C. The obtained product exhibited excellent dispersibility, heat resistance and resistance to solvents. The bleed test with plasticized polyvinylchloride as in Example 1 shows significantly less color migration than with conventional melamine-formaldehyde- sulfonamide pigments.

EXAMPLE 5

238.5 parts of prepolymer are prepared by operating as in Example 1 and mixed with 7.2 parts of moderately fluorescent dye with the structure (I),

at temperature 85-90°C for 3 hours.

Separately , an aqueous protective colloid solution was prepared by dissolving in 2000 parts of water 6.0 parts of CYANAMER A-370, 8.0 parts of Solsperse and 4.0 parts of SURFINOL CT-121 (produced by Air Product & Chemicals, Inc.). After raising the temperature of this aqueous solution to 70°C, 10 parts of triethylamine was added, and the mixture was stirred at 7000 rpm with a high speed agitator. While this aqueous solution of protective colloid was being stirred, 120 part of isophorone diamine was added and then the liquid prepolymer was slowly introduced to the protective colloid solution within 0.5 hour to obtain a bright yellow suspension. The suspension was held for 1 hour at 80°C with an intense stirring.

Properties:

The mean particle size of the particles was 3.5 and the softening temperature was 185- 190°C. The obtained product exhibited excellent dispersibility, heat resistance and resistance to solvents. The bleed test with plasticized polyvinylchloride as in Example 1 shows significantly less color migration than with conventional melamine- formaldehyde-sulfonamide pigments.

EXAMPLE 6

238.5 parts of prepolymer are prepared by operating as in Example 1 and mixed with 7.2 parts of moderately fluorescent dye with the structure (I), at temperature 85-90°C for 3 hours.

Separately, an aqueous protective colloid solution in 2000 parts of water was prepared by operating as in Example 5. After raising the temperature of this aqueous solution to 70°C, 10 parts of triethylamine was added, and the mixture was stirred at 7000 rpm with a high speed agitator. While this aqueous solution of protective colloid was being stirred, 120 parts of isophorone diamine was added and then the liquid prepolymer was slowly introduced to the protective colloid solution within 0.5 hour to obtain a bright yellow suspension. The suspension was held for 1 hour at 80°C with an intense stirring.

Properties: The mean particle size of the particles was 4.5 and the softening temperature was 184- 188°C. The obtained product exhibited excellent dispersibility, heat resistance and resistance to solvents. The bleed test with plasticized polyvinylchloride as in example 1 shows significantly less color migration than with conventional melamine- formaldehyde-sulfonamide pigments.

EXAMPLE 7

Separately, an aqueous protective colloid solution in 2000 parts of water was prepared by operating as in Example 5, 10.0 parts of triethylamine was added, and the mixture was stirred at 7000 rpm with a high speed agitator. While this aqueous solution of protective colloid was being stirred, 120 parts of isophorone diamine was added and then the liquid prepolymer was slowly introduced to the protective colloid solution within 0.5 hour to obtain a bright yellow suspension. The suspension was held for 1 hour at 80°C with an intense stirring.

Properties:

The mean particle size of the mainly spherical particles was 3.8 and the softening temperature was 180-185°C. The obtained product exhibited excellent dispersibility, heat resistance and resistance to solvents. The bleed test with plasticized polyvinylchloride as in Example 1 shows significantly less color migration than with conventional melamine-formaldehyde-sulfonamide pigments.

EXAMPLE 8

238.5 parts of prepolymer are prepared by operating as in Example 1 and mixed with 7.2 parts of moderately fluorescent dye with the structure (III), at temperature 85-90°C for 3 hours.

Separately, an aqueous protective colloid solution in 2000 parts of water was prepared by operating as in Example 5. After raising the temperature of this aqueous solution to 70°C, 10 parts of triethylamine was added, and the mixture was stirred at 7000 rpm with a high speed agitator. While this aqueous solution of protective colloid was being stirred, 120 parts of isophorone diamine was added and then the liquid prepolymer was slowly introduced to the protective colloid solution within 0.5 hour to obtain a bright yellow-orange suspension. The suspension was held for 1 hour at 80°C with an intense stirring.

Properties:

The mean particle size of the mainly spherical particles was 3.5 and the softening temperature was 192-196°C. The obtained product exhibited excellent dispersibility, heat resistance and resistance to solvents. The bleed test with plasticized polyvinylchloride as in Example 1 shows significantly less color migration than with conventional melamine-formaldehyde-sulfonamide pigments.

EXAMPLE 9

238.5 parts of prepolymer are prepared by operating as in Example 1 and mixed with 3.6 parts of moderately fluorescent dye with the structure (I), and 3.6 parts of Solvent Yellow 160 at temperature 85-90°C for 3 hours.

Separately, an aqueous protective colloid solution in 2000 parts of water was prepared by operating as in Example 5. After raising the temperature of this aqueous solution to 70°C, 10 parts of triethylamine was added, and the mixture was stirred at 7000 rpm with a high speed agitator. While this aqueous solution of protective colloid was being stirred, 120 parts of isophorone diamine were added and then the liquid prepolymer was slowly introduced to the protective colloid solution within 0.5 hour to obtain a bright yellow suspension. Next, the suspension was held for 1 hour at 80°C with an intense stirring.

Properties:

The mean particle size of the mainly spherical particles was 4.5 and the softening temperature was 199-202°C. The obtained product exhibited excellent dispersibility, heat resistance and resistance to solvents. The bleed test with plasticized polyvinylchloride as in Example 1 shows significantly less color migration than with conventional melamine-formaldehyde-sulfonamide pigments.

EXAMPLE 10

A 4-necked flask equipped with a stirrer, a reflux condenser and a thermocouple was charged with 200 parts of isophorone diisocyanate, 38.5 parts of paratoluenesulfonamide and 10 parts of triethylamine. While agitating this mixture, its temperature was raised to 70 °C, and the reaction was carried out for 1.5 hours to obtain a liquid prepolymer thus obtained is mixed with 7.2 parts of fluorescent dye Solvent Yellow 160 at temperature of 50-60 °C.

Separately, an aqueous protective colloid solution was prepared by dissolving in 2000 parts of water 6.0 parts of polyvinylpyrrolidone PVP K-30. After raising the temperature of this aqueous solution to 70 °C, 10 parts of triethylamine were added, and the mixture was stirred at 7000 rpm with a high speed agitator. While this aqueous solution of protective colloid was being stirred, the liquid prepolymer was slowly introduced to the protective colloid solution within 0.5 hour to obtain a bright yellow suspension. Next, the suspension was intensively stirred for 1 hour at 80 °C. The obtained product was separated from the suspension by filtration, and the filter cake was dried at a temperature of 150 °C for 4 hour to obtain 330 parts of aggregates of the pigment which were deagglomerated by means of a jet mill. Properties:

The mean particle size was 2.5 microns and the softening temperature was 210 - 215 °C The yellow fluorescent powder demonstrates extremely good dispersibility, good heat resistance and resistance to solvents. The bleed test with plasticized polyvinylchlorides as in Example 1 shows significantly less color migration than with conventional melamine-formaldehyde-sulfonamide pigments.

Claims

A thermoplastic fluorescent pigment obtained by the condensation of a diisocyanate prepolymer and an aliphatic diamine, a cycloaliphatic diamine or a mixture of a diamine and a polyol in the presence of a fluorescent dye, wherein the prepolymer is obtained by the reaction of an aromatic sulfonamide with an excess of aliphatic, cycloaliphatic and/or or aromatic diisocyanate, and wherein the molar excess of diisocyanate in the prepolymer equals the molar of the aliphatic diamine, the cycloaliphatic diamine or the mixture of a diamine and polyol in the condensation.

2. The thermoplastic fluorescent pigment of claim 1 , wherein the fluorescent dye is selected from the group consisting of a) a water-soluble fluorescent dye, b) an oil-soluble fluorescent dye and c) a moderately fluorescent polymer-soluble dye according to one of the formulae (I) to (V)

wherein

X is oxygen or NR₂' with R₂' independently being defined as R₂;

R_t is is hydrogen, halogen, -NR₂R₃, R₃-O- or R₃-S-,

R₂ is hydrogen, Cι.₆alkyl, C₆-ιoaryl, (C_6-ιo)aryl-(Cι.₆)alkyl or (d-eJalkyKCe-

₁₀)aryl, the alkyl and/or aryl radicals being substituted by hydroxyl, d-

₆alkoxy, C₆-iQaryloxy or halogen; R₃ is d.₆alkyl, C₆.ι₀aryl, (C₆-ιo)aryl-(C_1-6)alkyl or (d.₆)alkyl-(C₆.ιo)aryl, the alkyl and/or aryl radicals being substituted by hydroxyl, C_1-6alkoxy, C₆-ιoaryloxy or halogen; R₄ and R₅ independently being defined as R₂;

The thermoplastic fluorescent pigment of claim 1 , wherein the fluorescent dye is a member selected from the group of Basic Yellow 40, Solvent Yellow 160, Basonyl Red 485, Basonyl Red 560 and dye compounds according to formula (I) and (III), wherein X is oxygen or NR₂' with R₂' being hydrogen or methyl, R is hydrogen, Y is sulphur and n,m and p are from 2 to 6, preferably 2 or 3.

The thermoplastic fluorescent pigment of claim 1 , wherein the fluorescent dye is added in an amount of 1 to 5% by weight, preferably 2 to 4% by weight.

5. A method for preparing a pigment composition according to claims 1 , 2, 3 or 4 comprising the steps of

A) reacting a member selected from the group consisting of aliphatic, cycloaliphatic and aromatic diisocyanate and mixtures thereof with aromatic sulfonamide in the presence of a catalyst B) dyeing the prepolymer of A with a fluorescent dye or a combination of fluorescent dyes, C) introducing the dyed prepolymer of B into an aqueous solution of protective colloid optionally comprising a surfactant, D) reacting the suspension of C with a member from the group consisting of aliphatic or cycloaliphatic diamine or a mixture of aliphatic or cycloaliphatic diamine with polyols in the presence of a catalyst E) separating the hardened resin of D from the suspension followed by drying and deaggregating the dried hardened resin.

6. A method according to claim 5 wherein the catalyst in steps A and D is triethylamine and is present in an amount from 1 to 5% by weight.

7. A method according to claim 5 wherein the steps A and D are carried out at a temperature from 40 to 90°C, preferably from 50 to 60°C for step A and from 70 to 80°C for step D.

A method according to claim 5 wherein the aqueous suspension of protective colloid comprises 1 to 3% of water-soluble polymer.

A method according to claim 8 wherein the aqueous suspension of protective colloid further comprises 1 to 3% of a non-ionic surfactant or a mixture of non- ionic and ionic surfactant.

10. A method according to claim 5 wherein the dyed prepolymer is added under agitation and the reaction mixture is kept at a temperature from 70 to 80°C under continuing agitation for preferably 0.5 to 2 hours.

11. Use of a thermoplastic fluorescent pigment of claim 1 in the mass pigmentation of synthetic polymers, in printing inks, for the mass coloration of paper, for coating and printing textiles, in electrophotographic toners and developers, in powder coating materials and in ink-jet inks.

12. A polymerproduct comprising a thermoplastic fluorescent pigment according to claim 1.