DE4140295A1 - PIGMENTS WITH IMPROVED SHINE - Google Patents

Abstract

Improved gloss pigments are produced by coating platelike substrates and are characterised in that an aqueous suspension composed of a metallic salt and of metal oxide and/or dyestuff particles is hydrolytically precipitated on the platelike substrat as a metal oxide-and/or dyestuff particles-containing metal hydroxide layer.

Description

The invention relates to platelet-shaped pigments which Metal oxide particles are doped, high opacity and have an improved gloss.

Platelet-shaped pigments, which in addition to a high gloss, satisfactory interference as well as sufficient Having opacity is often very difficult to manufacture bar. Especially in the manufacture of colored platelet-shaped pigments, which are usually caused by Mixed precipitation are often obtained, the gloss or the Opacity not satisfactory. Also stand out platelet-shaped substrates with one or more Metal oxide layers are covered by interference and gloss from, but due to the transparent material insufficient opacity. The opacity can be through the deposition of relatively rough metal oxide layers be increased, however, the gloss decreases drastically. The use of metal substrates as platelet-shaped Backing materials also lead to a high Opacity, but at the same time causes a metallic Shine that is extremely annoying in most applications.  

There was therefore a great need for platelet-shaped Pigments, which are combined with a high gloss a high opacity and a special aesthetic Characterize attraction and which the range of available expand platelet-shaped, especially colored pigments and add.

The object of the present invention was to be ready provision of new pigments with favorable properties, which especially meet the aforementioned requirements and also valuable materials for technical application represent.

It was found that this task was developed the platelet-shaped pigments according to the invention is dissolved.

Surprisingly, by precipitating a metal oxide layer by hydrolysis of a metal salt solution, in counter were from small metal oxide and / or dye particles platelet-shaped pigment with a higher gloss and a improved hiding power compared to pigments obtained by conventional mixed precipitation will.

The invention thus relates to platelet-shaped pigments with high gloss and high opacity, consisting of a platelet-shaped carrier material, which from an inorganic is covered matrix in which metal oxide and / or Dye particles are contained in the submicrometer range, the coating being highly homogeneous.  

The invention also relates to a method of manufacture platelet-shaped pigments with improved gloss and hiding power, wherein platelet-shaped substrates in aqueous suspension by hydrolysis of metal salts with coated with a metal oxide or metal oxide hydrate layer and then separated, optionally washed, dried and annealed, characterized in that

• a) hydrolysis in the presence of metal oxide and / or Dye particles is carried out and
• b) the particles have a size in the submicrometer range sen.

The subject matter of the invention is also modified Process for the preparation of the pigments according to the invention as well as their use.

The pigments according to the invention consist of a platelet-shaped inorganic carrier material, as in for example glass, kaolin, muscovite, ilmenite or especially prefers mica. This platelet-shaped material will by precipitation with a metal hydroxide layer into which Metal oxide and / or organic dye particles embedded are coated, but the metal oxide and / or  organic dye particles when striking the hydroxide layer are carried along and no mixed precipitation in the conventional sense.

The platelet-shaped substrates preferably have a thickness between 0.1 and 5 µm, but especially between 0.2 and 4.5 µm. The linear expansion in the other two dimensions NEN is usually between 1 and 250 microns, especially preferably between 2 and 200 microns.

Suitable matrix oxides are, for example, silicon dioxide, Silicates, boron trioxide, borates, aluminum oxide, aluminates or but particularly preferably titanium dioxide, as well as all others known in the manufacture of platelet-shaped Pearl and colored pigments used materials.

They are usually based on appropriate soluble metal salts, preferably of halides, sulfa ten or nitrates, particularly preferably of chlorides Hydrolysis at appropriate pH values.

The metal oxide and / or organi embedded in the matrix dye particles have a size of 10-40 nm. You are therefore significantly smaller than the platelet-shaped pigment or as the metal oxides produced by mixed precipitation and are entrained in the precipitation of the matrix oxide and in the interstices of the matrix package built, which creates a higher packing density and associated higher deck strength and a higher gloss.  

The metal oxide and / or organic dye particles are generally stored randomly and preferably from amorphous or spherical shape.

Suitable metal oxide particles are all known stable inorganic oxides which do not react with the precursor materials of the matrix in the production of the pigments according to the invention. The metal oxide particles can be colorless or colored and are preferably added in pure form. However, it is also conceivable that mixtures of different metal oxides and / or organic pigments are used. Some particularly suitable metal oxides are titanium dioxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), silicon dioxide (SiO ₂ ), tin dioxide (SnO ₂ ), magnesium oxide (MgO), zinc oxide (ZnO), iron oxide, such as, for. B. Fe ₂ O ₃ or Fe ₃ O ₄ , chromium oxide (Cr ₂ O ₃ ), cerium dioxide (CeO ₂ ), tungsten oxide (WO ₃ ), molybdenum oxide (MoO ₃ ), zirconium dioxide (ZrO ₂ ), but also mixed oxides such as . B. Cr ₂ FeO ₄ , CoAl ₂ O ₄ or NiAl ₂ O ₄ .

In addition to inorganic pigment particles, organic Pigment particles are used, in particular tempera turstable organic pigments are preferred. Often can the manufacturing conditions of the invention Pigments e.g. B. by reducing the drying and possibly Annealing temperature with simultaneous increase in drying or glow duration or also varied by other measures be that less stable organic pigment particles can be used. In addition, it is frequently observed that the stability of the organic pigment particles through the Incorporation into the matrix is increased.  

As organic pigment particles such. B. preferably uses: phthalocyanines, varnish products of basic Dyes with heteropolyacids, anthroquinones, phenazines, Phenoxazines, diketopyrrolopyrroles or perylenes.

The pigment particles listed here are just like Ver are known for their manufacture (see e.g. H. Kittel, Scientific Publishing Company, Stuttgart 1960, G. Benzig, pigments for paints, Expert Verlag 1988) and they are usually commercially available. Are there to understand these pigment particles only as examples, and they are only intended to illustrate the invention without it in limit in any way. In addition to the explicitly mentioned Pigment particles can be a variety of other pigment particles be used.

In many cases it is beneficial for better dispergy tion of the pigment particles, the precursor solution and wetting agents add, e.g. B. non-ionic or ionic commercially available Guys. So z. B. polyethylene and polypropylene glycols well suitable. Neither the type nor the amount of net added means are critical, but in general the proportion is of the wetting agent at a maximum of 2% by weight, based on the disperser sion.

In a special embodiment of the pigments according to the invention, platelet-shaped carrier materials, preferably mica, are coated by hydrolysis with a titanium salt solution, preferably a titanium tetrachloride solution, which at the same time contains TiO ₂ particles in the rutile modification. These rutile particles are entrained during the precipitation and are stored in the matrix spaces. At the same time, they act as rutilization nuclei and cause the titanium dioxide coating to partially rutilize. The mass fraction of the rutile modification in the matrix is generally 0.5 to 40% by weight. The rutile particles have an average diameter between 10 and 40 nm. A platelet-shaped pigment with high gloss and great hiding power is formed, the proportion of the rutile modification being very strongly dependent on the annealing temperature. The calcination is preferably carried out at temperatures between 700 and 1000 °, particularly preferably between 800 and 900 °. The use of foreign layers for rutilization, such as. B. SnO _{2 is} omitted.

The storage of small metal oxide particles, with a average size of 10-40 nm in the cavities of the Metal oxide coating causes a significant increase in Opacity and shine combined with a high Homogeneity of the coating compared to pigments can be obtained by mixed precipitation.

The hiding power and - in the case of colored pigment particles - the absorption color of the inventions, independent of the observation angle Pigments according to the invention can be used in a further area the concentration of the embedded pigment particles varies will. The mass fraction of the loaded pigment particles is typically between 0.5 and 30% and especially between 2 and 20%.  

Also preferred are pigments according to the invention with one or more embedded organic and / or in particular inorganic colored pigments; iron oxides, chromium oxides, cobalt oxide and colored spinels such as z. B. cobalt alumina (CoAl ₂ O ₄ ).

The pigments according to the invention are thus optical systems with an excellent combination opti properties, the relative expression of which in addition With regard to the respective application in a wide range can be varied and optimized. Doing this can be optimistic tion by a person skilled in the art on the basis of the present Description can be done routinely without it inventive activity.

The pigments according to the invention thus represent a considerable one Enrich the range of technically usable pigments, and they are of considerable economic importance.

The pigments according to the invention are produced after wet chemical processes such as B. in US 30 87 828, DE 20 09 566, DE 22 14 545, DE 25 22 572, DE 25 22 573, DE 31 37 809, DE 31 51 354, DE 31 51 355, DE 32 11 602 or DE 32 35 017 are described and also in the pigment position by mixed precipitation.

The procedure is preferably such that an aqueous Manufacture suspension of a platelet-shaped substrate and tempered to a temperature between 5 and 95 °. To this  A suspension of a metal salt is then added to the suspension zes in the presence of metal oxide and / or organic color particles with a particle size in the submicrometer range rich, with the particles either in the substrate u bed or are finely dispersed in the metal salt solution or separately as an aqueous dispersion simultaneously with the Metal salt solution are added to the substrate suspension. The The pH of the substrate suspension is equal to timely addition of a base kept in a range suitable for the hydrolysis of the respective metal salt is suitable and a corresponding precipitation of the hydroxide causes. Here the previously added metal oxide and / or organic Dye particles carried away and into the cavities of the precipitated water-containing oxide layer. The coated substrate is separated, washed, dried and then at temperatures between 400 and 1200 °, preferably calcined at 600 to 1000 °.

However, one can also proceed in such a way that a suspension, ent holding the substrate to be coated, the ones to be stored Submicron particles and the metal salt, manufactures and that then the hydro by heating and / or adding a base lysis of the metal salt causes.

The examples below serve to illustrate the inven to explain in more detail without limiting it. Before and all temperatures are given below in ° C.  

example 1

100 g of mica are suspended in 2000 ml of water and heated to 75 °. A hydrochloric acid solution of 1.6 g of SnCl ₄ × 5 H ₂ O, dissolved in 50 ml of water, is then added to the reaction suspension. This is followed by the simultaneous addition of 355 ml of an aqueous TiCl ₄ solution (280 g TiCl ₄ / l) and of 355 ml of a dispersion consisting of 6 g Aero sil 200® (Degussa, highly disperse pyrogenic silica; particle size 10-20 nm) and 0.2 g Texopon K12® (Henkel, wetting agent based on lauryl sulfate) for the reaction mixture. The pH value is kept constant at pH 1.8. After the addition of the aforementioned reagents has ended, aqueous TiCl ₄ solution is added until the desired end point of the coating, in this case the silver end point, is reached. The mixture is then stirred for 15 minutes to complete, the pigment is filtered off, washed free of chloride and dried for 16 hours at a temperature of 120 °. The dry pigment is then annealed at 850 ° for 30 minutes.

Composition of the pigment: 51% mica, 1% SnO ₂ , 6% Aerosil 200®, approx. 42% TiO ₂ .

Example 2

Analogously to Example 1, instead of 6% Aerosil 200® 12% are dropped into the TiO ₂ layer. The composition of the pigment is: 44% mica, 1% SnO ₂ , 12% Aerosil 200®, approx. 43% TiO ₂ .

Example 3

100 g of mica are suspended in 2000 ml of water and heated to 75 ° C. A suspension of 5 g of Micro Titanium Oxide MT 100-S® (Teikoku Kaku, particle size 10-30 nm) in 300 ml of aqueous titanium tetrachloride solution (280 g of TiCl ₄ / l) is then slowly added to the reaction mixture. During the metering, the pH is kept constant at 1.8. When the addition is complete, the mixture is stirred for 15 minutes to complete the reaction. The pigment is then filtered off, washed free of chloride and dried at 120 ° for 16 hours. After drying is complete, the mixture is annealed at 800 ° for 30 minutes. The TiO ₂ layer consists of 20% rutile and 80% anatase.

Example 4

The procedure is analogous to Example 3. Only the final annealing temperature is increased to 850 °. A platelet-shaped pigment with a TiO ₂ coating consisting of 40% rutile and 60% anatase is obtained.

Example 5

Analogously to Example 3, mica flakes are coated by precipitation with a TiO ₂ layer. The dried product is annealed at 900 °. A platelet-shaped TiO ₂ coated pigment is obtained, the TiO ₂ layer of which has a composition of 30% rutile and 70% anatase.

Claims (9)

1. Pigments with high gloss and high hiding power, consisting best of a platelet-shaped carrier material which is coated with an inorganic matrix, characterized in that metal oxide and / or dye particles are contained in the submicron range in this matrix. 2. Pigments according to claim 1, characterized in that as platelet-shaped substrate contains mica. 3. Pigments according to claim 1, characterized in that the average size of the embedded metal oxide and / or Dye particles is 10-40 nm. 4. Pigments according to claim 1, characterized in that the added metal oxide particles are TiO ₂ particles in the rutile modification. 5. Process for the production of platelet-shaped pigments with improved gloss and hiding power, whereby platelets shaped substrates in aqueous suspension by hydrolysis  of metal salts with a metal oxide or metal oxide coated with hydrate layer and then separated, optionally washed, dried and annealed, characterized in that the hydrolysis in the presence of metal oxide and / or dye particles with a Size is carried out in the submicron range. 6. The method according to claim 5, characterized in that mica is used as the platelet-shaped substrate. 7. The method according to claim 5, characterized in that the mean size of the metal oxide and / or dye par particle is 10-40 nm. 8. The method according to claim 5, characterized in that TiO ₂ particles are added in the rutile modification. 9. Use of pigments according to claims 1 to 6 in Formulations such as paints, dyes, plastics and Cosmetics.