MXPA99004927A - Mix of pigme - Google Patents

Abstract

The present invention relates to pigment mixtures consisting of at least two components, component A which are SiO2 flakes coated with one or more metal and / or metal oxides, and component B which is one or more electrically conductive pigments, and its use in varnishes, paints, inks for printing and plastic

Description

MIXTURE. OF PIGMENT DESCRIPTION OF THE INVENTION The present invention relates to pigment mixtures consisting of at least two components, component A which is flakes of SIOO2 coated with one or more metal oxides and / or metals and component B which is one or more pigments conductors of electricity, and its use in varnishes, paints, inks for printing and plastics. For various application areas, currently electrically conductive pigments are prepared with which it is possible, for example, to produce antistatic coatings for electronic equipment; antistatic coatings for floors, antistatic finishes for areas protected against explosions or electrically conductive primers for painting plastics. To produce dark conductive pigments, carbon black, graphite and graphite coated with nickel are currently used, and to produce light colored pigments, metal platelets and mixed oxides are used, such as tin oxide added with antimony. These mixed oxides may be in the form in which they were applied to the vehicles, examples being mica, Sio2, glass or barium sulfate.

REF .: 30337 However, due to its high absorption of light in the visible spectral range, carbon black and graphite can not be used for transparent, pale or colored coatings. A further problem is the strong absorption in the infrared (IR) range, which causes the frequently unwanted heating of the coated articles, for example when exposed to sunlight. Metal platelets have the disadvantage that they are susceptible to corrosion and in aqueous formulations they can cause hydrogen to form. The inorganic oxides or mixed oxides used to date, in the form of platelets with mica, for example, as carrier material or in a form in which the dimensions in the three spatial directions are approximately equal, such as tin oxide added with antimony without a vehicle, require, as a result of its geometric shape, the use of high concentrations in order to exhibit a different effect. However, the application of an additional layer to the pigment involves a considerable additional expense in the production and makes the product more expensive. In addition, the pigment has conductivity values that do not meet the high requirements. In order to improve the conductivity of polymeric systems such as plastics, paints or Inks for printing, for example, it is known from German Patent DE-A 42 12 950 that a pigment can be used which consists of a component A, which consists of one or more electrically conductive platelet-shaped pigments and a component B which comprises one or more non-platelet-shaped pigments electrically conductive. Now, it has surprisingly been found that a mixture of pigments comprising SiO2 flakes coated in combination with electrically conductive pigments has better conductive properties than the conductive pigments by themselves. Thus, the present invention provides a pigment mixture consisting of at least two components, a component A which are SiO2 flakes coated with one or more metal oxides and / or metals, and a component B which is one or more conductive pigments of electricity, and provides its use in varnishes, paints, inks for printing and plastics. Similarly, the present invention provides the formulations, such as paints, varnishes, powder coating materials, printing inks, plastics and agricultural films, which comprise the pigment mixture of the present invention. SÍO2 coated flakes can be mixed in any proportion with the electrically conductive pigments. The preferred ratio of component A to component B is from 1:10 to 10: 1, in particular from 1: 2 to 2: 1. SÍO2 flakes produced in a continuous band in accordance with International Publication WO 93/08237, are based on a transparent matrix with platelet shape, colorful or colorless and generally have a thickness between 0.1 and 5 μm, in particular between 0.2 and 2.0 μm. The other two dimensions generally fall between 1 and 250 μm, preferably between 2 and 100 μm and, in particular, between 5 and 40 μm. The leaflets of SÍO2 have one or more metallic layers and / or layers of metallic oxides. Examples of metal oxides or mixtures of metal oxides are titanium dioxide, zirconium oxide, zinc oxide, iron oxides and / or chromium oxide, especially TiO 2 and / or F 2 β 3. The SiO2 flakes can be coated, for example, in the manner described in International Publication WO 93/08237 (wet chemical coating) or in German Patent DE-A 196 14 637 (CVD process). Instead of the outer metal oxide layer, a semitransparent layer of metal can be used. Suitable metals for this are, for example, Cr, Ti, Mo, W, Al, Cu, Ag, Au and Ni. The preferred pigments have the following structure of layers: flakes of SÍO2 + metal + SÍO2 + metallic oxide. To induce special color effects, fine particles in the nanometer size range can be additionally incorporated into the metal oxide layers of high or low refractive index. Examples of such suitable amounts are finely divided TiO2 or finely divided carbon (carbon black), with particle sizes in the range of 10 to 250 nm. A controlled influence on luster and concealment can be exerted by virtue of the light scattering properties of such particles. Preferably, the SiO2 flakes are coated with one or more metal oxides. By conductive pigments of component B, all pigments known to those skilled in the art are understood and comprise platelet-shaped, needle-like or fiber-like materials, such as mica platelets, glass platelets, SiO2 flakes, ceramic platelets. , glass fibers, alumina fibers or titanium dioxide fibers, which are coated with a conductive layer. Carbon fibers are also suitable, although in this case additional conductive coatings are not necessary, since the fibers already have a enough conductivity. The terms "needle particles" and "fiber-like particles" mean those having a length to diameter ratio greater than 5. Suitable platelet-shaped pigments are known, for example, from European Patent EP 0 373 575 The present invention additionally provides paints, printing inks, plastics or powder coating materials, which are pigmented with the pigment mixture of the present invention. The proportion of the pigment mixture in them is from 1 to 80% by weight, preferably more than 2% by weight, based on the total solids content of the system in which it is used. As the conductive layer in a vehicle, zinc oxide added with aluminum and titanium dioxide or tin oxide added with antimony, halogens with and / or phosphorus is particularly suitable. The conductive layer is applied in the conventional manner, in accordance, for example, with the process described in European Patent EP-A 0 139 557. In this process it is possible to use all customary metallic oxides and / or mixtures of metal oxides. A selection of such materials is provided in European Patent EP-A 0 139 557 on page 5, lines 5-19. However, the application of a layer is preferred tin oxide conductor added with antimony, which is applied in an amount of 25 to 100% by weight, in particular in an amount of 50 to 75% by weight, based on the substrate in the form of a platelet. In the case of using a layer of zinc oxide added with aluminum, the proportion of the conductive layer is preferably 40 to 200% by weight based on the carrier material, without using preferably proportions of 100 to 200. % in weigh. If the conductive layer consists of tin oxide (IV) or titanium dioxide added with at least one halide, preferably fluoride, then the proportion of the conductive layer is 20 to 200% by weight, preferably 60 to 150% by weight, based on the vehicle. Pigments of this type are known, for example, from German Patent DE-A 42 43 163. In the case of the conductive layer comprising tin oxide added with phosphorus, the proportion of the conductive layer is from 25 to 100% by weight, based on the substrate, especially 50 to 75% by weight. Pigments of this type are known, for example, from German Patent DE-A 44 35 301. Although it is possible to use larger amounts, these do not produce any additional increase in conductivity and the pigments become darker and darker.

The tin / antimony ratio is preferably from 2: 1 to 20: 1, in particular from 5: 1 to 10: 1. If the content of antimony is too low, it is impossible to achieve high conductivities, while with a high antimony content the pigments become darker and darker. The electrically conductive platelet-shaped pigments that can be assigned to component B of the pigment mixture of the present invention can be obtained commercially under the trademarks Minatec® (Merck KGaA, Dar stadt) and Zelec® ECPM (DuPont). A product marketed under the trademark Minatec © CM 31 consists of mica flakes coated with tin dioxide added with antimony. Under the designation of Minatec® CM 30, a conductive pigment consisting of mica coated with titanium dioxide and having as a conductive layer a layer of tin dioxide added with antimony is marketed. The combination of SiO2 flakes with conductive, platelet-shaped and / or acicular particles produces electrically conductive products whose electrical properties are better than those of a conductive pigment alone. The advantages become particularly distinguishable in systems where pigments are used, especially in the case of incorporation in plastics. The use of the concentrations required for the pigment mixture of the present invention in the plastic (pigment volume concentration) are markedly lower than in the case of conventional conductive pigments. This is advantageous not only for the cost, but also for the properties of the system in which the pigments are used, since the properties of the plastic are retained more effectively per se if there is a need to introduce less pigment. The specific use of fiber-shaped conductive pigments often also produces a stabilization addition of the mechanical properties of the plastic. The pigment mixture of the present invention is simple and easy to handle. The pigment mixture can be incorporated into the system in which it is to be used by simple agitation. No grinding and dispersion of the pigments is necessary. The pigment mixture of the present invention can be used to pigment coated materials, printing inks, plastics, agricultural films for coating seeds or for colored foods. The concentration of the pigment mixture in the system in which it is to be used for pigmenting is generally between 0.01 and 50% by weight, preferably between 0.1 and 10% by weight, based on the solids content of the system. This Concentration usually depends on the specific application. The plastics comprising the pigment mixture of the present invention in amounts of 0.1 to 50% by weight, in particular 0.5 to 7% by weight, are often notable for a particular sparking effect. The plastics comprising the pigment mixture of the present invention in amounts of 0.1 to 10% by weight, moreover, are highly suitable for laser marking. The marking operations carried out, for example, cor. A laser of C02 or Nd-YAG, produce very defined and abrasion resistant brands. In the coatings sector, the pigment mixture is used in amounts of 5 to 35% by weight. The proportion in which the leaflets of SÍO2 are mixed with the compcne te B, depends on the desired effect. The SÍO2 flakes are preferably used with component B in a ratio of 1: 5, especially 1: 3. In the coating material, the pigment mixture of the present invention has the advantage that the desired color inversion effect is obtained with a single layer finish. This inversion of color is extremely pronounced. In comparison with coatings comprising a pigment of mica-based interface instead of coated SiO2 flakes, coatings with the pigment mixture of the present invention exhibit a marked deep effect and a shimmering effect. In the pigmentation of binder systems, for example for paints and inks for rotogravure printing, offset printing or screen printing, pigment mixtures consisting in particular of SiO2 flakes coated with Minatec® (Merck KGaA, Darmstadt) have been found particularly suitable. ). The pigment mixture is incorporated into the printing ink in amounts of 2 to 35% by weight, preferably 5 to 25% by weight and, in particular, from 8 to 20% by weight. The mixing ratio of component A with respect to component B is preferably in the range of 1: 5 to 5: 1. The printing inks comprising the pigment mixture of the present invention exhibit more pure dyes and have better printing characteristics due to the good viscosity values. Thus, the present invention also provides formulations comprising the pigment mixture of the present invention. The Examples presented below are intended to illustrate the invention, without limiting it.

EXAMPLES Example 1 Ink for rotogravure printing Consists of: 70 g of binder based on nitrocellulose from Gebrüder Schmidt, 95MB011, with a solids content of 20% 15 g of Minatec® 31 CN (conductive pigment from Merck KGaA, Darmstadt, RFA) 15 g of SiO2 flakes coated with TiO2, with a particle size of 5 to 40 μm 30 g of l-ethoxy-2-propanol Example 2 Plastic 1 kg of polyethylene granules (PE-HD) were uniformly moistened in a mixer of drum with 2 g of an adhesion agent. Then 10 g of SiO2 flakes coated with TiO2 with a particle size of 5 to 40 μm and 2 g of Iriodin® LS 825 (Merck KGaA pigment, Darmstadt, RFA) with a particle size < 15 μm and the components were mixed for 2 minutes. These granules were processed under the conventional conditions in an injection molding machine, for obtain small staggered plates with measurements of 4 x 3 x 0.5 c. The small stepped plates are remarkable for their luster and laser marking. EXAMPLE 3 Coating material 30 g of SiO2 flakes coated with IO2 with a particle size of 5-40 μm (Merck KGaA) 10 g of Minatec 40 CM (Merck KGaA conductive pigment) 42 g of paint base (AU system) -MF, solids = 19%) 18 g of disinfectant mixture The coating is characterized by unsightly properties and a reversal of color from pale lilac to pale green. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (1)

CLAIMS Having described the invention as an antecedent, the content of the following claims is claimed as property: 1. A pigment mixture characterized in that it comprises at least two components, the component A being SiO2 flakes coated with one or more metal oxides and / or metals, and component B being one or more conductive pigments of electricity. 2. The pigment mixture according to claim 1, characterized in that component A comprises SiO2 flakes coated with TiO2 and / or Fe2 3- 3-3. The pigment mixture according to any of claims 1 or 2, characterized because component B comprises platelets of SiO2 or mica platelets coated with one or more metal oxides and having as a conductive layer a layer of tin dioxide added with antimony, fluorine and / or phosphorus. 4. The pigment mixture according to any of claims 1 to 3, characterized in that component A and component B are mixed in a ratio of 10: 1 to 1:10. 5. The use of the pigment mixture according to claim 1 in paints, varnishes, inks for printing, plastics, coloring seeds and for laser marking. 6. A formulation characterized in that it comprises a pigment mixture according to claim

1.