FR2769612A1 - New oxynitrited compounds based on an alkaline earth metal and tantalum or niobium - Google Patents

Abstract

The new compounds are suitable as yellow or orange colored pigments for a wide variety of substrates to replace conventional products such as lead chromate, lead molybdate etc. which have a high toxicity. The compositions conform to general formula (I); A = an alkaline earth metal; M = Ta or Nb (or one partially substituted by the other); y = is greater or equal to 0.33 and less than or equal to 0.5; x = is greater than 0 and less than or equal to (7-3y)/6. A precursor of formula (II) is also claimed; M = as above; y = greater than 0.33 and less than 0.5. Independent claims are also included for the preparation and use of the compositions.

Description

OXYNITRIDE COMPOSITION BASED ON ALKALINE EARTH AND
TANTALIUM OR AN ALKALINO-EARTH AND NIOBIUM. METHODS OF
PREPARATION AND USE AS COLORING PIGMENT
RHONE-POULENC CHEMISTRY
The present invention relates to an oxynitrided composition based on an alkaline earth metal and tantalum or an alkaline earth metal and niobium, the processes for preparing this composition and its use as a coloring pigment.

 The inorganic pigments for coloring are already widely used in many industries, particularly in the fields of paints, plastics and ceramics. In such applications the properties of, among others, thermal and / or chemical stability, dispersibility (ability of the product to disperse correctly in a given medium), compatibility with the medium to be colored, intrinsic color, power staining and opacifying power are all particularly important criteria to consider in choosing a suitable pigment.

 Unfortunately, the problem is that most of the inorganic pigments which are suitable for applications as above and which are actually used to date on an industrial scale, generally use metals (cadmium, lead, chromium, cobalt in particular ), the use of which is becoming more and more strictly regulated, or even prohibited, by the legislation of many countries, given their very high toxicity. More particularly, by way of non-limiting examples, mention may be made of yellow / orange pigments of the chromate or molybdate type of lead or cadmium sulphide.

 So we see that there is a significant need for new mineral pigments substitution.

 The object of the present invention is therefore to provide a substitute pigment in the range of yellow or orange.

For this purpose, the composition of the invention is an oxynitrided composition based on an alkaline earth and at least one element selected from tantalum and niobium, characterized in that it has an overall composition corresponding to the Formula 1 )
A1 + yM1 yo (7-3y-6x) t2N2x where A is alkaline earth, M tantalum or niobium or one of these two elements partially substituted by the other and y and x satisfy the following equations: 0.33 <y10.5 and O <xS (7-3y) / 6
The invention also relates to a precursor composition which is based on strontium and tantalum and / or niobium, characterized in that it has an overall composition corresponding to formula (2): Sr + yM-y0 (7-3y) Where M is defined as above and 0.33 <y <0.5.

Other characteristics, details and advantages of the invention will emerge even more completely on reading the description and the drawings which will follow and in which:
FIG. 1 is an X-ray diffraction diagram of a precursor composition
according to the invention;
FIG. 2 is an X-ray diffraction diagram of a precursor composition and
different nitrided compositions according to the invention.

 The precursor composition mentioned above will be described first.

This composition is based on strontium, tantalum and / or niobium and oxygen. The atomic ratio Sr / M varies between 2.01 and 2.99 and more particularly between 2.16 and 2.48 when M is tantalum. This ratio can be equal to 2.33. The composition is mainly in the form of a phase of the perovskite type either cubic double parameter parameter or pseudocubic. This phase corresponds to the general formula ABo, 5Mo, 5X3 with:
A = Sr
B = Sr, Ta
M = Ta or Nb
X = O, where O represents a gap.

 The composition may have a gap phase on the anionic network.

 When M is tantalum and the Sr / Ta ratio is between 2.16 and 2.99, the composition is in the form of a pure phase.

 In the particular case where the Sr / Ta ratio is equal to 2.33, the composition is in the form of a pure phase of formula Sr (Sr0.4Ta0.1) Ta0.5O2.9E] 0.1.

 The mesh parameter varies depending on the Sr / M ratio. For M = Ta, it is between 8.259 and 8.285 for a Sr / Ta ratio of between 2.16 and 2.48 and equal to 8.329 for a Sr / Ta ratio of 2.99.

 The composition may also contain, in substitution for strontium, a rare earth or an alkaline earth other than strontium.

 Rare earth means the elements of the group constituted by yttrium and the elements of the periodic classification of atomic number inclusive between 57 and 71.

 The rare earth may be more particularly lanthanum.

 The alkaline earth may be more particularly barium or calcium.

 The precursor composition of the invention may also comprise titanium or zirconium as a partial substitution of tantalum and / or niobium.

 The invention also relates to the nitrided composition of formula (1) given above.

 The overall atomic ratio A / M may vary between 2 and 3 and more particularly between 2.16 and 2.48.

 The composition may comprise titanium or zirconium as a partial substitution of the element M. It may also comprise a rare earth or an alkaline earth metal in addition to the element A.

 In the particular case where A denotes strontium and M is tantalum and / or niobium, the nitrided composition has the same structure (cubic or pseudo cubic perovskite phase) as that of the precursor composition of formula (2). Therefore, everything that has been described above applies here too.

 The nitrided composition has a color that varies from pale yellow to bright orange depending on the level of nitrogen. We go from bright yellow to orange by increasing this rate. A noticeable color can be obtained from 0.5% by mass of nitrogen.

 The nitrided composition and the precursor composition of the invention generally have a particle size of at most 5 μm, more particularly at most 3 μm (CILAS particle size).

 The methods for preparing the compositions of the invention will now be described.

 The precursor composition is prepared by a process in which a mixture of solid compounds of element A, element M and, where appropriate, the substitution element or elements: rare earth, alkaline earth metal, titanium, zirconium and / or niobium, and then the mixture formed is heated.

 This is a process employing a solid-solid type reaction.

As solid compounds, oxides, oxalates or carbonates are generally used. The compounds are mixed in the stoichiometric proportions of the desired composition and then heated. The heating is conducted under conditions of temperature and duration which make it possible to obtain the formation of the precursor oxide (composition and phase). Heating is usually done under air. The calcination temperature may be at least 900 ° C and the duration may be about ten hours.

 It is possible to make several subsequent heating and to grind the product between these different heaters.

 When at least one carbonate-type compound is used, it may be advantageous to carry out heating in two stages. In this case, the mixture is heated initially at a temperature sufficient to cause decarbonation of the mixture, then, in a second time, it is heated to a temperature sufficient to form the aforementioned product. The first heating can be done at a temperature between 800 and 100000. The second can be done at a temperature of at least 120000. The second heating can be replaced by several successive heating with intermediate grinding of the product as indicated above.

 The nitrided compositions can be obtained by nitriding the precursor compositions. This nitriding can be done by heating a precursor composition in the presence of ammonia. The nitrogen content in the nitrided product is adjusted by adjusting the temperature and the heating time. For example, the temperature of the heating for nitriding is at least 500 ° C, it may be between 700 and 1000 ° C. The duration may vary depending on the nature of the precursor between 1 and 800 hours for example.

 It is possible to add carbon to the precursor compositions during the nitriding which facilitates this nitriding. Heating for nitriding can also be done by microwave. It is also possible to carry out directly the nitriding, by ammonia, of the mixtures which serve for the preparation of precursor compositions.

 Other methods are also usable. Thus, a mixture of an alkaline earth salt, such as a strontium nitrate, a salt of the element M, may be formed as a tantalum chloride and, optionally, substitution elements, in a medium organic (alcohol for example) or aqueous and then precipitated by addition of a basic compound such as ammonia and / or by addition of carbon dioxide. The precipitate obtained is optionally dried, calcined and then nitrided in the manner described above.

 Another method consists in reacting a salt of the alkaline earth A and a salt of the element M and, optionally the salts of the substitution elements, with a nitride of the Li 3 N type in an organic medium such as benzene or xylene then subjecting the product of the reaction to a heat treatment.

 It is also possible to react a tantalum nitride or oxynitride with the oxides or carbonates of the other constituents of the desired composition, in an inert medium, under ammonia or under vacuum. The substitution elements may also be in the form of nitride or oxynitride.

 The invention also relates to the use as a coloring pigment for coloring a material of a nitrided composition as described above or as obtained by the methods described above.

 The nitrided composition of the invention has indeed a coloring power and a covering power and, therefore, suitable for coloring many materials, such as plastics, paints and others.

 Thus, and more specifically, it can be used in the coloring of polymers for plastics which may be of the thermoplastic or thermosetting type.

As thermoplastic resins capable of being colored according to the invention, mention may be made, by way of illustration only, of polyvinyl chloride, polyvinyl alcohol, polystyrene, styrene-butadiene, styrene-acrylonitrile and acrylonitrilebutadiene-styrene copolymers (ABS ), acrylic polymers including polymethyl methacrylate, polyolefins such as polyethylene, polypropylene, polybutene, polymethylpentene, cellulose derivatives such as for example cellulose acetate,
Cellulose acetate butyrate, ethylcellulose, polyamides including polyamide 6-6.

 As regards the thermosetting resins for which the nitrided composition according to the invention is also suitable, mention may be made, for example, of phenoplasts, aminoplasts, in particular the urea-formaldehyde, melamine-formaldehyde copolymers, epoxy resins and thermosetting polyesters.

 The nitrided composition of the invention can also be used in special polymers such as fluorinated polymers, in particular polytetrafluoroethylene (PTFE), polycarbonates, silicone elastomers and polyimides.

 In this specific application for coloring plastics, it is possible to use the nitrided composition of the invention directly in the form of powders. It can also preferably be used in a pre-dispersed form, for example by premixing with a portion of the resin, in the form of a paste concentrate or a liquid, which makes it possible to introduce it to any stage of the manufacture of the resin.

 Thus, the nitrided composition according to the invention can be incorporated in plastics such as those mentioned above in a proportion by weight ranging generally from 0.01 to 5% (referred to the final product) or from 20 to 70% in the case of a concentrate.

 The nitrided composition of the invention can also be used in the field of paints and varnishes and more particularly in the following resins alkyd resins, the most common is called glycerophthalic; resins modified with long or short oil; acrylic resins derived from esters of acrylic acid (methyl or ethyl) and methacrylic acid optionally copolymerized with ethyl acrylate, 2-ethylhexyl or butyl; vinyl resins such as, for example, polyvinyl acetate, polyvinyl chloride, butyralpolyvinyl, formalpolyvinyl, and copolymers of vinyl chloride and vinyl acetate or vinylidene chloride; the aminoplast or phenolic resins most often modified; polyester resins; polyurethane resins; epoxy resins; silicone resins.

 Generally, the nitrided composition is used in a proportion of 5 to 30% by weight of the paint, and 0.1 to 5% by weight of the glaze.

 In addition, the nitrided composition according to the invention is also likely to be suitable for applications in the rubber industry, in particular in floor coatings, in the paper and printing ink industry, in the field of cosmetic, as well as for many other uses such as, for example, and not limited to, dyes, in leather for finishing thereof and laminate coatings for kitchens and other worktops, ceramics and glazes.

 The nitrided composition of the invention may also be used in the coloring of materials based on or obtained from at least one inorganic binder.

 This inorganic binder may be chosen from hydraulic binders, aerial binders, plaster and anhydrous or partially hydrated calcium sulphate binders.

 By hydraulic binders is meant substances having the property of setting and hardening after addition of water by forming hydrates insoluble in water. The products of the invention are particularly applicable to the coloring of cements and of course concretes made from these cements by adding thereto water, sand and / or gravel.

 In the context of the present invention, the cement may, for example, be of the aluminous type. By this is meant any cement containing a high proportion of either alumina as such or aluminate or both. By way of example, mention may be made of cements based on calcium aluminate, in particular those of the SECAM type.

 The cement may also be of the silicate type and more particularly based on calcium silicate. Examples of these are PORTLAND cements and, in these types of cements, quick-setting or high-speed Portland, white cements, sulphate-resistant cements and those comprising blast-furnace slags and / or fly ash and / or meta-kaolin.

 Mention may also be made of cements based on hemihydrate, calcium sulphate as well as magnesium cements known as Sorel cements.

 The nitrided composition of the invention is also used in the coloration of air binders, ie binders curing in the open air by the action of CO2, the oxide type or hydroxide of calcium or magnesium.

The nitride composition of the invention is finally used in the coloration of plaster and anhydrous or partially hydrated calcium sulphate binders (CaSO 4 and
CaSO4, 1 / 2H20).

 Finally, the invention relates to compositions of colored materials, in particular of the plastics, paints, stains, rubbers, ceramics, glazes, papers, inks, cosmetics, dyes, leathers, laminates or of the type based on or obtained from at least one inorganic binder, which comprises, as coloring pigment, a nitrided composition according to the invention or obtained by a nitriding process of the type described above.

 Examples will now be given.

The chromatic coordinates L *, a * and b * are given in the CIE 1976 system (L *, a * and b *) as defined by the International Lighting Commission and listed in the French Standards Compendium (AFNOR), color color nO
X08-12, No. X08-14 (1983), which are determined for measurements of products and plastics using a colorimeter marketed by
Pacific Scientific Corporation. The nature of the illuminant is the D65. The observation surface is a circular pellet of 12.5 cm 2 area. The observation conditions correspond to a vision with an aperture angle of 10. In the given measurements, the specular component is excluded.

EXAMPLE 1
This example relates to the preparation of a precursor composition.

 Stoichiometric amounts of strontium carbonate SrCO3 and tantalum oxide Ta2O5 were weighed to give a Sr / Ta ratio of 2.33. It is ground in alcohol in an agate mortar. The mixture is heated at 900 ° C. under air for 2 hours to decarbonate, and is then heated under air at 135 ° C. for 9 hours, the product is then ground and a second heating is carried out under the same conditions.

 A composition is obtained which has the diffraction pattern RX of FIG. 1. This composition contains only the Sr1, 4Ta0, 6O2, 9 phase.

EXAMPLE 2
The composition of Example 1 is heated in the presence of ammonia. The following table shows the heating conditions and the characteristics of the products obtained.

Table 1

<tb> Tests <SEP> Temperature <SEP>#<SEP> Time <SEP> Color <SEP> Rate <SEP> of nitrogen <SEP> Formulation
<tb><SEP> (C) <SEP> (h) <SEP> L / a * / b * <SEP> (% <SEP> mass)
<tb><SEP> 1 <SEP> 750 <SEP> 15 <SEP> yellow <SEP> very <SEP> pale <SEP> 0.5 <SEP> 0.5 <SEP> Sr.Tao.O.5No. î
<tb><SEP> 74 / -2 / 6
<tb><SEP> 2 <SEP> 800 <SEP> 15 <SEP> yellow <SEP> bright <SEP> 1,4 <SEP> Sr1.4Ta0.6O2.47N0.28
<tb><SEP> 65/1/41
<tb><SEP> 3 <SEP> 800 <SEP> 24 <SEP> yellow <SEP> bright <SEP> 1.3 <SEP> Sr1.4Ta0.6O2.52N0.25
<tb><SEP> 65/2/43
<tb><SEP> 4 <SEP> 850 <SEP> 15 <SEP> yellow <SEP> orange <SEP> bright <SEP> 1,9 <SEP> Sr1.4Ta0.6O2.345N0.37
<tb><SEP> 65/7/49
<tb><SEP> 5 <SEP> 900 <SEP> 15 <SEP> orange <SEP> bright <SEP> 2,6 <SEP> Sr1.4Ta0.6O2.14N0.51
<tb><SEP> 54/21/58
<tb><SEP> 6 <SEP> 900 <SEP> 60 <SEP> orange <SEP> alive <SEP> 2,4 <SEP> Sr1.4Ta0.6O2.20N0.47
<tb><SEP> 63/31/67
<tb><SEP> 7 <SEP> 800 <SEP> 800 <SEP> yellow <SEP> orange <SEP> bright <SEP> 3,6 <SEP> Sr1.4Ta0.6O1.85N0.7
<Tb>
The X-ray diffraction diagrams of the products of tests 2, 4 and 5 as well as of that of example 1 are given in FIG. 2. The compositions of example 2 mainly comprise a single perovskite phase.

EXAMPLE 3
This example illustrates the preparation of compositions comprising titanium.

The procedure is as in Example 1 using titanium oxide. Two heats are carried out for test 8 and three heats for test 9. Two compositions of formula
test 8: Sr1, 4Ta0,54Ti0,06O2,87
test 9: 9: Sr1,4Ta0,5Ti0,1O2,85
In both cases, the composition contains only the perovskite phase.

 The composition of test 8 is then heated under ammonia at 800 ° C. for 15 hours. There is obtained a bright yellow composition comprising 1.30% by weight of nitrogen of formula Sr1, 4Ta0.54Ti0.06O2.53N0.25 and which contains mainly a perovskite type phase.

 The coordinates L / a * / b * are respectively 63 / 0.7 / 40.

EXAMPLE 4
This example illustrates the preparation of a composition containing niobium of formula Sr1,33Nb0,67O3-3xN2x.

 The precursor composition is prepared as in the example from strontium carbonate and niobium oxide Nb 2 O 5 in the stoichiometric proportions to have a Sr / Nb ratio of 2. The precursor composition is then nitrided.

 The conditions of nitriding and the characteristics of the products obtained are given in Table 2 below.

Table 2

<tb> Tests <SEP> Temperature <SEP> Time <SEP> Color <SEP>#<SEP> Rate <SEP> Nitrogen <SEP> Formulation
<tb><SEP> (C) <SEP> (h) <SEP> Ua * / b * <SEP> (% <SEP> mass)
<tb><SEP> 10 <SEP> 700 <SEP> 15 <SEP> 66/3/27 <SEP> 0.35 <SEP> Sr1.33Nb0.67L2.91N0.056
<tb><SEP> 11 <SEP> 700 <SEP> 60 <SEP> 60/10/33 <SEP> 1.25 <SEP> Sr1.33Nb0.67O2.7N0.2
<tb><SEP> 12 <SEP> 750 <SEP> 15 <SEP> 50/18/39 <SEP> 1.95 <SEP> Sr1.33Nb0.67O2.53N0.31
<tb><SEP> 13 <SEP> 800 <SEP> 15 <SEP> 40/24/36 <SEP> 3.25 <SEP> Sr1.33Nb0.67O2.23N0.51
<Tb>
EXAMPLE 5
This example relates to the preparation of a precursor composition of formula Ca1, LPa0,67O3 and the nitrided composition.

 The procedure is as in Example 1 starting from the stoichiometric amounts of calcium carbonate and tantalum oxide. The product obtained has a perovskite structure of monoclinic symmetry.

 Nitriding is carried out at 950 C for 15 hours. The nitrogen content is 1.4% by weight.

 The chromatic coordinates Ua * / b * of the nitrided composition are 75 / -6 / 58.

 EXAMPLE 6 10 g of the product of test 4 of Example 2 are mixed in a rotating cube with 2 kg of a reference polypropylene ELTEX # PHV 001. The mixture is then injected at 220 ° C. using a KAPSA model Protoject 10/10 injection molding machine with a 41 s cycle.

The mold is maintained at a temperature of 35 C.

 In this way, a parallelepipedic test piece with double thickness (2 and 4 mm) is obtained.

The chromatic coordinates measured on the thick part of the wafer are as follows:
Ua * / b * = 741-3 / 40

Claims (12)

CLAIMS 1- Oxiditrided composition based on an alkaline earth and at least one element selected from tantalum and niobium, characterized in that it has an overall composition corresponding to formula (1): A1 + yM1- yO (7-3y-6x) / 2N2x wherein A is alkaline earth, M tantalum or niobium or one of these two elements partially substituted by the other and y and x satisfy the following equations: 33 # y # 0.5 and 0 <(7-3y) / 6. 2- Composition based on strontium and tantalum and / or niobium characterized in that it has an overall composition corresponding to the formula (2): Sri + yM1-y0 (7-3y) / 2 wherein M denotes the tantalum or niobium or one of these two elements partially substituted by the other and 0.33 <y <0.5. 3. Composition according to claim 1 or 2, characterized in that A is strontium and in that it comprises a phase which has a perovskite structure is cubic parameter double mesh or pseudocubic. 4 Composition according to one of the preceding claims, characterized in that the overall atomic ratio NM or Sr / Ta is more particularly between 2.16 and 2.48. 5. Composition according to rune of claims 3 or 4, characterized in that it is in the form of a pure phase.  6. Composition according to one of the preceding claims, characterized in that it further comprises a rare earth or an alkaline earth in substitution of the element A or strontium. 7- The composition of claim 6, characterized in that the rare earth is lanthanum.  8 Composition according to claim 6, characterized in that the alkaline earth is barium or calcium. 9- Composition according to one of claims 1 to 8, characterized in that it further comprises titanium or zirconium partial substitution of the element M. 10- Process for the preparation of a composition according to one of the preceding claims, characterized in that a mixture of solid compounds of the element A, the element M and, where appropriate, the element or elements substitution, the mixture is heated whereby a precursor composition is obtained and, where appropriate, nitride this precursor composition. 11- Process according to claim 10, characterized in that at least one carbonate-type compound is used, the mixture is initially heated to a temperature sufficient to cause decarbonation of the mixture, then, in a second step, to a temperature sufficient to form the precursor composition. 12- A method according to claim 10 or 11, characterized in that nitride the precursor composition by heating in the presence of ammonia. 13- Process for the preparation of a composition according to one of claims 1 to 9, characterized in that a mixture of salts of the elements A and M is formed, is precipitated by addition of a basic compound, the precipitate is calcined by which a precursor composition is obtained and then, if necessary, this precursor composition is nitrided.  1S Process for the preparation of a composition according to claim 1 or according to one of claims 3 to 9 in combination with claim 1, characterized in that a salt of the element A, a salt of the element M and, optionally, the salts of the substitution elements, with a nitride and then subjecting the reaction product to a heat treatment. 15- Process for the preparation of a composition according to claim 1 or according to one of claims 3 to 9 in combination with claim 1, characterized in that a mixture of solid compounds of the element A, element M and, where appropriate, the substitution element or elements, then the mixture is nitrided. 16- A process for coloring a material, characterized in that the coloring pigment used is a composition according to claim 1 or one of claims 3 to 9 in combination with claim 1, or a nitrided composition obtained by a process according to one of claims 10 to 15. 17- The method of claim 16, characterized in that the above composition is used as pigment in plastics, paints, stains, rubbers, ceramics, glazes, papers, inks, cosmetics, dyes, leathers, laminate coatings and materials based or obtained from at least one mineral binder.  18 Compositions of colored material, in particular of plastics, paints, stains, rubbers, ceramics, glazes, paper, inks, cosmetics, dyes, leathers, laminates or base-type coatings or obtained from at least one mineral binder, characterized in that they comprise, as a coloring pigment, a composition according to claim 1 or one of claims 3 to 9 in combination with claim 1, or a nitrided composition obtained by a process according to claim 10 to 15.