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EP0961814A1 - Titania pigment, preparation and use - Google Patents

Titania pigment, preparation and use

Info

Publication number
EP0961814A1
EP0961814A1 EP98903097A EP98903097A EP0961814A1 EP 0961814 A1 EP0961814 A1 EP 0961814A1 EP 98903097 A EP98903097 A EP 98903097A EP 98903097 A EP98903097 A EP 98903097A EP 0961814 A1 EP0961814 A1 EP 0961814A1
Authority
EP
European Patent Office
Prior art keywords
layer
pigment
weight
oxyhydroxide
titanium dioxide
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98903097A
Other languages
German (de)
French (fr)
Inventor
Anny Guez
Caroline Steiner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Millennium Inorganic Chemicals SA
Original Assignee
Millenium Inorganic Chemicals SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Millenium Inorganic Chemicals SA filed Critical Millenium Inorganic Chemicals SA
Publication of EP0961814A1 publication Critical patent/EP0961814A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/36—Compounds of titanium
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/36—Compounds of titanium
    • C09C1/3607—Titanium dioxide
    • C09C1/3653—Treatment with inorganic compounds
    • C09C1/3661—Coating
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
    • C01P2004/84—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases one phase coated with the other
    • C01P2004/88—Thick layer coatings

Definitions

  • the present invention relates to a titanium dioxide pigment having a surface treatment suitable for its use in paint compositions with high external resistance.
  • Titanium dioxide is used for its pigmentary properties in paint compositions. Titanium dioxide pigments are generally treated with mineral compounds in order to improve their application properties such as their dispersibility, their whiteness or their covering power.
  • the titanium dioxide pigment is known to absorb UV rays. It thus protects the organic matrix into which it is introduced (paint, plastic, ...) from degradation under the effect of this type of rays.
  • titanium dioxide has photocatalytic properties so that it degrades the organic compounds in contact with it under the effect of these same UV rays. This degradation is characterized by chalking of the paint.
  • Mineral treatments therefore also aims to avoid direct contact between titanium dioxide and the organic components of the matrix.
  • it is known, for example, to use mineral treatments based on silica and / or alumina.
  • surface treatments were insufficient when the pigment was used in paint compositions for exterior coatings highly exposed to the sun.
  • An object of the present invention is to provide a titanium dioxide pigment, the mineral surface treatment of which gives the exterior paints good resistance over time and very particularly low chalking and good retention of the gloss.
  • the invention relates to a titanium dioxide pigment, comprising a titanium dioxide core successively covered with a layer of hydroxide or zirconium oxyhydroxide, then a layer of titanium hydroxide or oxyhydroxide, then a layer of a phosphate and silica coprecipitate and finally a layer of alumina oxyhydroxide.
  • the invention also relates to a process for the preparation of this pigment which consists in carrying out the following operations:
  • a layer of zirconium hydroxide or oxyhydroxide is precipitated on the surface of the pigment
  • a layer of a phosphate and silica coprecipitate is precipitated on the surface of the pigment
  • a layer of alumina oxyhydroxide is precipitated on the surface of the pigment, - the pigment is recovered from the suspension.
  • the invention relates to the use of this pigment in paints and plastics.
  • the invention therefore relates, first of all, to a titanium dioxide pigment, comprising a titanium dioxide core successively covered with a layer of zirconium hydroxide or oxyhydroxide, then with a layer of hydroxide or titanium oxyhydroxide, then a layer of a phosphate and silica coprecipitate and finally a layer of alumina oxyhydroxide.
  • the different layers which cover the titanium dioxide have a thickness generally between 50 and 100 ⁇ . These layers may be discontinuous, more or less regularly surrounding the titanium dioxide.
  • the pigment according to the invention is covered with:
  • zirconium hydroxide or oxyhydroxide expressed as ZrO 2
  • silica 0.2 to 1.5% by weight of silica, expressed as SiO 2 ,
  • the invention also relates to a method of surface treatment of this titanium dioxide pigment. This process includes the following steps:
  • a layer of zirconium hydroxide or oxyhydroxide is precipitated on the surface of the pigment
  • a layer of a phosphate and silica coprecipitate is precipitated on the surface of the pigment
  • a layer of alumina oxyhydroxide is precipitated on the surface of the pigment, - the pigment is recovered from the suspension.
  • the treatment therefore consists in producing a first layer of zirconium hydroxide or oxyhydroxide or oxyhydroxide directly on the surface of the pigment, then in a second layer of titanium hydroxide or oxyhydroxide, then a third layer which is a coprecipitate of phosphate and silica, and finally a last layer of alumina oxyhydroxide.
  • an aqueous suspension of titanium dioxide pigments comprising titanium dioxide, preferably, predominantly in rutile form.
  • This suspension can be formed by any means known to those skilled in the art such as, for example, by the sulphate or chlorine processes.
  • the concentration of titanium dioxide pigments in this suspension usually varies between 100 and 500 g / l.
  • This dispersion may optionally contain a dispersant in order to disperse and stabilize it. It can in particular be obtained by grinding a dispersion of titanium dioxide using said dispersant.
  • the dispersant can be chosen from the following products: amino 2-methyl 2-propanol 1, potassium or sodium tetrapyrophosphate, potassium or sodium hexametaphosphate or alkaline salts of polyacrylic acid polymer or copolymer such as ammonium or sodium salts of polyacrylic acid.
  • phosphate-based dispersants these are generally present in a concentration of the order of 0.1 to 0.5% by weight expressed as P 2 O 5 relative to the weight of the dioxide of titanium.
  • the surface treatment process is generally carried out at a temperature above 60 ° C. This temperature is maintained throughout the treatment, but it is also possible to consider simply raising the temperature of the starting dispersion to a temperature above 80 ° C., then continuing the treatment without a heat source.
  • the first stage of the treatment consists in depositing by precipitation a layer of zirconium hydroxide or oxyhydroxide on the surface of the pigment.
  • a layer of zirconium hydroxide or oxyhydroxide is precipitated from a hydrolyzable zirconium compound chosen from zirconium sulfate, zirconium orthosulfate, zirconium chloride or l zirconium oxychloride.
  • the amount of hydrolyzable zirconium compound introduced during this first step is generally between 0.5 and 1.5% by weight, expressed as ZrO, relative to the core of titanium dioxide to be treated, preferably, between 0.2 and 1.5%.
  • the second stage of the treatment consists in depositing by precipitation a layer of titanium hydroxide or oxyhydroxide on the surface of the pigment.
  • a layer of titanium hydroxide or oxyhydroxide is precipitated from a hydrolyzable titanium compound chosen from titanium chloride, titanium oxychloride or titanium sulfate.
  • the quantity of hydrolyzable titanium compound introduced during the second step is generally between 0.05 and 1% by weight, expressed as TiO 2 , relative to the titanium dioxide core to be treated.
  • the first two steps are carried out at a pH usually between 4 and 6, preferably 5.
  • the pH can generally be controlled by adding an acid and / or a base such as sulfuric acid, hydrochloric acid or acetic acid, and soda or potash.
  • the third stage of the treatment consists in depositing by precipitation a layer of a phosphate and silica coprecipitate on the surface of the pigment.
  • a layer of a phosphate and silica coprecipitate is precipitated from hydrolyzable phosphorus and silicon compounds chosen from: phosphoric acid, phosphates such as potassium or sodium tetrapyrophosphate, potassium or sodium hexametaphosphate, potassium or sodium tripolyphosphate, sodium dihydrogen phosphate,
  • the amount of hydrolyzable phosphorus compound introduced during this step is generally between 0.2 and 1.5% by weight, expressed as P 2 O 5 relative to the titanium dioxide core to be treated.
  • the hydrolyzable silicon compound it is generally between 0.2 to 1.5% by weight, expressed as SiO 2 , relative to the titanium dioxide core to be treated.
  • this step is usually carried out at a pH between 6 and 9.
  • the pH can be controlled by adding phosphoric acid and / or another acid such as than sulfuric acid or hydrochloric acid.
  • the pH can also be controlled by the simultaneous and / or alternative introduction of the phosphorus-based compound and the silicon compound which will form the coprecipitate. This is the case, for example, when phosphoric acid and sodium silicate are used during this coprecipitation.
  • the quantities of phosphorus and silicon compounds introduced are modulated so as to precipitate a coprecipitate layer having a P / Si atomic ratio of between 0.3 and 3, preferably between 0.6 and 1, 2.
  • the amount of phosphate provided by the dispersant is subtracted from the amount of phosphate introduced during the third precipitation step.
  • the phosphorus compound and then the silicon compound are successively introduced into the aqueous suspension of titanium dioxide pigment.
  • the fourth step is to deposit a layer of alumina.
  • alumina layer is understood here and throughout the description to be a precipitate of aluminum oxyhydroxide.
  • this last layer is precipitated from a hydrolyzable aluminum compound such as basic hydroxylated salts.
  • a hydrolyzable aluminum compound such as basic hydroxylated salts.
  • the sodium aluminate the basic aluminum chloride, the aluminum hydroxide diacetate.
  • Alumina sulfate can also be used.
  • the amount of hydrolyzable aluminum compound introduced during this step is usually between 1 and 5% expressed by weight of AI 2 O 3 relative to the weight of the titanium dioxide core to be treated, preferably between 2% and 4%.
  • This precipitation takes place at the pH necessary for the precipitation of the alumina layer.
  • This pH can be between 3 and 10.
  • this pH is between 5 and 10.
  • the regulation can be carried out by adding sulfuric acid.
  • ripening stages can be carried out.
  • the latter consist in stirring the reaction mixture following the introduction of the hydrolysable compounds allowing precipitation.
  • the ripening time is of the order of 5 to 30 minutes at each stage.
  • the pigments are separated from the liquid phase of the suspension by any known means, for example by filtration. Then the pigment is generally washed with water, dried and micronized.
  • the pigments according to the invention can also be treated with organic compounds in order to give them properties specific to their use, such as gloss, dispersibility, wetting, stabilization.
  • organic compounds can be chosen from liquid or solid polyols such as low molecular weight polyglycols ethoxylated or not, trimethylolpropane (TMP), trimethylolethane (TME), ethoxylated trimethylolpropane, liquid polyphosphates, hydroxyamines such as triethanolamine (TEA), 2-amino-2-methyl-1-propanol (AMP) or silicone products.
  • TMP trimethylolpropane
  • TME trimethylolethane
  • ethoxylated trimethylolpropane liquid polyphosphates
  • hydroxyamines such as triethanolamine (TEA), 2-amino-2-methyl-1-propanol (AMP) or silicone products.
  • This organic treatment can be carried out in the aqueous phase after the fourth precipitation step, or after the pigments have
  • the invention finally relates to the use of pigments according to the invention in coating compositions, in particular paint, as well as in plastic compositions for which the pigment according to the invention avoids blueing over time.
  • the pigments according to the invention can also be used in laminates of paper.
  • the following examples illustrate the invention without, however, limiting its scope.
  • the starting point is a suspension of titanium dioxide with a concentration of 900 g / l. It was ground in the presence of 0.2% by weight of aminomethylpropanol (AMP90) relative to the weight of titanium dioxide, then diluted to 350 g / l.
  • AMP90 aminomethylpropanol
  • the pH of the dispersion is adjusted to 5 by the addition of sulfuric acid.
  • TiO 2 0.15% by weight of TiO 2 , relative to the weight of titanium dioxide to be treated, is added to the preceding reaction medium, in the form of a solution of titanium oxychloride.
  • SiO 2 - 0.7% by weight of SiO 2 , relative to the weight of titanium dioxide to be treated, in the form of a sodium silicate solution.
  • the pH is adjusted to 9.5 with sodium hydroxide.
  • the dispersion is then filtered.
  • the titanium dioxide pigments obtained are washed with water at 45 ° C, dried at 150 ° C for 15 hours.
  • comparative pigment 1 titanium dioxide pigment covered with a surface treatment based on 2.8% by weight of I 2 O 3 and 0.8% by weight of ZrO 2 ,
  • comparative pigment 2 titanium dioxide pigment coated with a surface treatment based on 3.5% by weight of AI 2 O 3 , 0.6% by weight of ZrO 2 and 0.6% by weight of P 2 O 5 ,
  • comparative pigment 3 titanium dioxide pigment covered with a surface treatment based on 2.2% by weight of AI O 3 and 5% by weight of SiO 2 .
  • the paint is based on an alkyd binder and a melamine in a 70/30 ratio by weight.
  • the pigment rate is around 37% by weight.
  • paints are applied on an aluminum support, for chalking measurements, or on a glass support, for gloss measurements, over a thickness between 40 and 90 ⁇ m. They are pre-dried for 30 min, then baked at 130 ° C for 30 min.
  • Accelerated aging The aluminum supports coated with paint are introduced into an accelerated aging device QUVB.
  • the aging cycle is as follows:
  • the chalking of the paint reaches a saturation value of 80%:
  • the gloss of the paint is: - 66 for the pigment according to the invention.
  • the specific formulation of the mineral treatment according to the invention provides the paint with a slower appearance of chalking and a gloss retention at least as high as for the comparative treatments.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Pigments, Carbon Blacks, Or Wood Stains (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Paints Or Removers (AREA)
  • Paper (AREA)

Abstract

The invention concerns a novel titania pigment useful for external painting. This pigment has a titania nucleus coated successively with a layer of zirconium hydroxide or oxyhydroxide, then a layer of titanium hydroxide or oxyhydroxide, then of a layer of co-precipitated phosphate and silica, and finally a layer of aluminium oxyhydroxide. The invention also concerns a method for preparing said pigment and its use in paints, plastics and laminated paper.

Description

PIGMENT DE DIOXYDE DE TITANE, SA PREPARATION ET SON UTILISATION TITANIUM DIOXIDE PIGMENT, ITS PREPARATION AND ITS USE
La présente invention a trait à un pigment de dioxyde de titane présentant un traitement de surface adapté à son utilisation dans des compositions de peinture à haute tenue extérieure.The present invention relates to a titanium dioxide pigment having a surface treatment suitable for its use in paint compositions with high external resistance.
Le dioxyde de titane est utilisé pour ses propriétés pigmentaires dans les compositions de peinture. Les pigments de dioxyde de titane sont en général traités par des composés minéraux afin d'améliorer leurs propriétés d'application telles que leur dispersibilité, leur blancheur ou leur pouvoir couvrant.Titanium dioxide is used for its pigmentary properties in paint compositions. Titanium dioxide pigments are generally treated with mineral compounds in order to improve their application properties such as their dispersibility, their whiteness or their covering power.
Ces traitements permettent aussi d'améliorer la tenue dans le temps des peintures à base de dioxyde de titane en conservant les caractéristiques physico-chimiques d'origine de la peinture malgré une exposition extérieure, notamment : le brillant, la stabilité de la couleur, les propriétés mécaniques du film.These treatments also make it possible to improve the resistance over time of paints based on titanium dioxide while retaining the original physico-chemical characteristics of the paint despite external exposure, in particular: the gloss, the color stability, the mechanical properties of the film.
Outre sa fonction pigmentaire, le pigment de dioxyde de titane est connu pour absorber les rayons UV. Il protège ainsi la matrice organique dans laquelle il est introduit (peinture, plastique, ...) d'une dégradation sous l'effet de ce type de rayons.Besides its pigmentary function, the titanium dioxide pigment is known to absorb UV rays. It thus protects the organic matrix into which it is introduced (paint, plastic, ...) from degradation under the effect of this type of rays.
Simultanément, le dioxyde de titane présente des propriétés photocatalytiques si bien qu'il dégrade les composés organiques se trouvant à son contact sous l'effet de ces mêmes rayons UV. Cette dégradation est caractérisée par le farinage de la peinture. Les traitements minéraux vise donc également à éviter le contact direct entre le dioxyde de titane et les composants organiques de la matrice. Dans ce but, il est connu, par exemple, d'utiliser des traitements minéraux à base de silice et/ou d'alumine. Cependant, il a été observé que de tels traitements de surface étaient insuffisants lorsque le pigment était utilisé dans des compositions de peinture pour des revêtements extérieurs fortement exposés au soleil.At the same time, titanium dioxide has photocatalytic properties so that it degrades the organic compounds in contact with it under the effect of these same UV rays. This degradation is characterized by chalking of the paint. Mineral treatments therefore also aims to avoid direct contact between titanium dioxide and the organic components of the matrix. For this purpose, it is known, for example, to use mineral treatments based on silica and / or alumina. However, it has been observed that such surface treatments were insufficient when the pigment was used in paint compositions for exterior coatings highly exposed to the sun.
Un but de la présente invention est de proposer un pigment de dioxyde de titane dont le traitement de surface minéral confère aux peintures extérieures une bonne tenue dans le temps et tout particulièrement un faible farinage et une bonne rétention du brillant.An object of the present invention is to provide a titanium dioxide pigment, the mineral surface treatment of which gives the exterior paints good resistance over time and very particularly low chalking and good retention of the gloss.
Dans ce but, l'invention concerne un pigment de dioxyde de titane, comprenant un noyau de dioxyde de titane recouvert successivement d'une couche d'hydroxyde ou d'oxyhydroxyde de zirconium, puis d'une couche d'hydroxyde ou d'oxyhydroxyde de titane, puis d'une couche d'un coprécipité de phosphate et de silice et enfin d'une couche d'oxyhydroxyde d'alumine.To this end, the invention relates to a titanium dioxide pigment, comprising a titanium dioxide core successively covered with a layer of hydroxide or zirconium oxyhydroxide, then a layer of titanium hydroxide or oxyhydroxide, then a layer of a phosphate and silica coprecipitate and finally a layer of alumina oxyhydroxide.
L'invention concerne aussi un procédé de préparation de ce pigment qui consiste à mettre en oeuvre les opérations suivantes :The invention also relates to a process for the preparation of this pigment which consists in carrying out the following operations:
- on forme une suspension aqueuse de pigments de dioxyde de titane,an aqueous suspension of titanium dioxide pigments is formed,
- dans une première étape, on précipite une couche d'hydroxyde ou d'oxyhydroxyde de zirconium à la surface du pigment,- in a first step, a layer of zirconium hydroxide or oxyhydroxide is precipitated on the surface of the pigment,
- dans une deuxième étape, on précipite une couche d'hydroxyde ou d'oxyhydroxyde de titane à la surface du pigment,- in a second step, a layer of titanium hydroxide or oxyhydroxide is precipitated on the surface of the pigment,
- dans une troisième étape, on précipite une couche d'un coprécipité de phosphate et de silice à la surface du pigment,in a third step, a layer of a phosphate and silica coprecipitate is precipitated on the surface of the pigment,
- dans une quatrième étape, on précipite une couche d'oxyhydroxyde d'alumine à la surface du pigment, - on récupère le pigment à partir de la suspension.- In a fourth step, a layer of alumina oxyhydroxide is precipitated on the surface of the pigment, - the pigment is recovered from the suspension.
Enfin, l'invention concerne l'utilisation de ce pigment dans les peintures et les plastiques.Finally, the invention relates to the use of this pigment in paints and plastics.
D'autres détails et avantages de l'invention apparaîtront plus clairement à la lecture de la description et des exemples.Other details and advantages of the invention will appear more clearly on reading the description and the examples.
L'invention concerne donc, tout d'abord, un pigment de dioxyde de titane, comprenant un noyau de dioxyde de titane recouvert successivement d'une couche d'hydroxyde ou d'oxyhydroxyde de zirconium, puis d'une couche de d'hydroxyde ou d'oxyhydroxyde de titane, puis d'une couche d'un coprécipité de phosphate et de silice et enfin d'une couche d'oxyhydroxyde d'alumine.The invention therefore relates, first of all, to a titanium dioxide pigment, comprising a titanium dioxide core successively covered with a layer of zirconium hydroxide or oxyhydroxide, then with a layer of hydroxide or titanium oxyhydroxide, then a layer of a phosphate and silica coprecipitate and finally a layer of alumina oxyhydroxide.
Pour l'ensemble de la description, les différentes couches qui recouvrent le dioxyde de titane présentent une épaisseur comprise en général entre 50 et 100 Â. Ces couches peuvent être discontinues, entourant de manière plus ou moins régulière le dioxyde de titane.For the whole of the description, the different layers which cover the titanium dioxide have a thickness generally between 50 and 100 Å. These layers may be discontinuous, more or less regularly surrounding the titanium dioxide.
Habituellement, le pigment selon l'invention est recouvert de :Usually, the pigment according to the invention is covered with:
- 0,5 à 1 ,5 % en poids d'hydroxyde ou d'oxyhydroxyde de zirconium, exprimé en ZrO2,- 0.5 to 1.5% by weight of zirconium hydroxide or oxyhydroxide, expressed as ZrO 2 ,
- 0,05 à 1 % en poids d'hydroxyde ou d'oxyhydroxyde de titane, exprimé en TiO2, - 0,2 à 1 ,5 % en poids de phosphate, exprimé en P2O5,- 0.05 to 1% by weight of titanium hydroxide or oxyhydroxide, expressed as TiO 2 , - 0.2 to 1.5% by weight of phosphate, expressed as P2O5,
- 0,2 à 1 ,5 % en poids de silice, exprimé en SiO2,0.2 to 1.5% by weight of silica, expressed as SiO 2 ,
- 2 à 4 % en poids d'oxyhydroxyde d'aluminium, exprimé en AI2O3, les pourcentages étant exprimés en poids par rapport au noyau de dioxyde de titane.- 2 to 4% by weight of aluminum oxyhydroxide, expressed as AI 2 O 3 , the percentages being expressed by weight relative to the titanium dioxide core.
L'invention concerne également un procédé de traitement de surface de ce pigment de dioxyde de titane. Ce procédé comprend les étapes suivantes :The invention also relates to a method of surface treatment of this titanium dioxide pigment. This process includes the following steps:
- on forme une suspension aqueuse de pigments de dioxyde de titane,an aqueous suspension of titanium dioxide pigments is formed,
- dans une première étape, on précipite une couche d'hydroxyde ou d'oxyhydroxyde de zirconium à la surface du pigment,- in a first step, a layer of zirconium hydroxide or oxyhydroxide is precipitated on the surface of the pigment,
- dans une deuxième étape, on précipite une couche d'hydroxyde ou d'oxyhydroxyde de titane à la surface du pigment,- in a second step, a layer of titanium hydroxide or oxyhydroxide is precipitated on the surface of the pigment,
- dans une troisième étape, on précipite une couche d'un coprécipité de phosphate et de silice à la surface du pigment,in a third step, a layer of a phosphate and silica coprecipitate is precipitated on the surface of the pigment,
- dans une quatrième étape, on précipite une couche d'oxyhydroxyde d'alumine à la surface du pigment, - on récupère le pigment à partir de la suspension.- In a fourth step, a layer of alumina oxyhydroxide is precipitated on the surface of the pigment, - the pigment is recovered from the suspension.
Le traitement consiste donc à réaliser une première couche d'hydroxyde ou d'oxyhydroxyde ou d'oxyhydroxyde de zirconium directement à la surface du pigment, puis à une deuxième couche d'hydroxyde ou d'oxyhydroxyde de titane, puis une troisième couche qui est un coprécipité de phosphate et de silice, et enfin une dernière couche d'oxyhydroxyde d'alumine.The treatment therefore consists in producing a first layer of zirconium hydroxide or oxyhydroxide or oxyhydroxide directly on the surface of the pigment, then in a second layer of titanium hydroxide or oxyhydroxide, then a third layer which is a coprecipitate of phosphate and silica, and finally a last layer of alumina oxyhydroxide.
Selon le procédé de l'invention, on part d'une suspension aqueuse de pigments de dioxyde de titane comprenant du dioxyde de titane, de préférence, majoritairement sous forme rutile. Cette suspension peut être formée par tout moyen connu de l'homme du métier tel que, par exemple, par les procédés sulfate ou chlore.According to the process of the invention, one starts with an aqueous suspension of titanium dioxide pigments comprising titanium dioxide, preferably, predominantly in rutile form. This suspension can be formed by any means known to those skilled in the art such as, for example, by the sulphate or chlorine processes.
La concentration des pigments de dioxyde de titane dans cette suspension varie habituellement entre 100 et 500 g/l.The concentration of titanium dioxide pigments in this suspension usually varies between 100 and 500 g / l.
Cette dispersion peut contenir éventuellement un dispersant afin de la disperser et stabiliser. Elle peut en particulier être obtenue par broyage d'une dispersion de dioxyde de titane à l'aide dudit dispersant. On peut choisir le dispersant parmi les produits suivants : l'amino 2-méthyl 2-propanol 1 , le tétrapyrophosphate de potassium ou de sodium, l'hexamétaphosphate de potassium ou de sodium ou des sels alcalins de polymère ou de copolymère d'acide polyacrylique tels que les sels d'ammonium ou de sodium d'acide polyacrylique. Dans le cas où des dispersants à base de phosphate sont utilisés, ceux-ci sont présents généralement dans une concentration de l'ordre de 0,1 à 0,5 % en poids exprimé en P2O5 par rapport au poids du dioxyde de titane. Le procédé de traitement de surface est généralement effectué à une température supérieure à 60 °C. Cette température est maintenue pendant tout le traitement, mais on peut aussi envisager de simplement élever la température de la dispersion de départ à une température supérieure à 80 °C, puis de continuer le traitement sans source de chaleur.This dispersion may optionally contain a dispersant in order to disperse and stabilize it. It can in particular be obtained by grinding a dispersion of titanium dioxide using said dispersant. The dispersant can be chosen from the following products: amino 2-methyl 2-propanol 1, potassium or sodium tetrapyrophosphate, potassium or sodium hexametaphosphate or alkaline salts of polyacrylic acid polymer or copolymer such as ammonium or sodium salts of polyacrylic acid. In the case where phosphate-based dispersants are used, these are generally present in a concentration of the order of 0.1 to 0.5% by weight expressed as P 2 O 5 relative to the weight of the dioxide of titanium. The surface treatment process is generally carried out at a temperature above 60 ° C. This temperature is maintained throughout the treatment, but it is also possible to consider simply raising the temperature of the starting dispersion to a temperature above 80 ° C., then continuing the treatment without a heat source.
La première étape du traitement consiste à déposer par précipitation une couche d'hydroxyde ou d'oxyhydroxyde de zirconium à la surface du pigment.The first stage of the treatment consists in depositing by precipitation a layer of zirconium hydroxide or oxyhydroxide on the surface of the pigment.
Habituellement, au cours de cette première étape, on précipite une couche d'hydroxyde ou d'oxyhydroxyde de zirconium à partir d'un composé hydrolysable du zirconium choisi parmi le sulfate de zirconium, l'orthosulfate de zirconium, le chlorure de zirconium ou l'oxychlorure de zirconium.Usually, during this first step, a layer of zirconium hydroxide or oxyhydroxide is precipitated from a hydrolyzable zirconium compound chosen from zirconium sulfate, zirconium orthosulfate, zirconium chloride or l zirconium oxychloride.
La quantité de composé hydrolysable du zirconium introduite au cours de cette première étape est, en général, comprise entre 0,5 et 1,5 % en poids, exprimé en ZrO , par rapport au noyau de dioxyde de titane à traiter, de préférence, comprise entre 0,2 et 1 ,5 %.The amount of hydrolyzable zirconium compound introduced during this first step is generally between 0.5 and 1.5% by weight, expressed as ZrO, relative to the core of titanium dioxide to be treated, preferably, between 0.2 and 1.5%.
La deuxième étape du traitement consiste à déposer par précipitation une couche d'hydroxyde ou d'oxyhydroxyde de titane à la surface du pigment. Habituellement, au cours de cette deuxième étape, on précipite une couche d'hydroxyde ou d'oxyhydroxyde de titane à partir d'un composé hydrolysable du titane choisi parmi le chlorure de titane, l'oxychlorure de titane ou le sulfate de titane.The second stage of the treatment consists in depositing by precipitation a layer of titanium hydroxide or oxyhydroxide on the surface of the pigment. Usually, during this second step, a layer of titanium hydroxide or oxyhydroxide is precipitated from a hydrolyzable titanium compound chosen from titanium chloride, titanium oxychloride or titanium sulfate.
La quantité de composé hydrolysable du titane introduite au cours de la deuxième étape est, en général, comprise entre 0,05 et 1 % en poids, exprimé en TiO2, par rapport au noyau de dioxyde de titane à traiter.The quantity of hydrolyzable titanium compound introduced during the second step is generally between 0.05 and 1% by weight, expressed as TiO 2 , relative to the titanium dioxide core to be treated.
Afin d'obtenir la précipitation des hydroxydes, on effectue les deux premières étapes à un pH habituellement compris entre 4 et 6, de préférence de 5. Le pH peut être en général contrôlé par l'ajout d'un acide et/ou d'une base tels que l'acide sulfurique, l'acide chlorhydrique ou l'acide acétique, et la soude ou la potasse.In order to obtain the precipitation of the hydroxides, the first two steps are carried out at a pH usually between 4 and 6, preferably 5. The pH can generally be controlled by adding an acid and / or a base such as sulfuric acid, hydrochloric acid or acetic acid, and soda or potash.
La troisième étape du traitement consiste à déposer par précipitation une couche d'un coprécipité de phosphate et de silice à la surface du pigment.The third stage of the treatment consists in depositing by precipitation a layer of a phosphate and silica coprecipitate on the surface of the pigment.
Habituellement, au cours de cette troisième étape, on précipite une couche d'un coprécipité de phosphate et de silice à partir de composés hydrolysables du phosphore et du silicium choisis parmi : - l'acide phosphorique, les phosphates tels que le tétrapyrophosphate de potassium ou de sodium, l'hexamétaphosphate de potassium ou de sodium, le tripolyphosphate de potassium ou de sodium, le dihydrogénophosphate de sodium,Usually, during this third step, a layer of a phosphate and silica coprecipitate is precipitated from hydrolyzable phosphorus and silicon compounds chosen from: phosphoric acid, phosphates such as potassium or sodium tetrapyrophosphate, potassium or sodium hexametaphosphate, potassium or sodium tripolyphosphate, sodium dihydrogen phosphate,
- les silicates de sodium ou de potassium.- sodium or potassium silicates.
La quantité de composé hydrolysable du phosphore introduite au cours de cette étape est, en général, comprise entre 0,2 et 1 ,5 % en poids, exprimé en P2O5 par rapport au noyau de dioxyde de titane à traiter. Pour le composé hydrolysable du silicium, elle est en général comprise entre 0,2 à 1 ,5 % en poids, exprimé en SiO2, par rapport au noyau de dioxyde de titane à traiter.The amount of hydrolyzable phosphorus compound introduced during this step is generally between 0.2 and 1.5% by weight, expressed as P 2 O 5 relative to the titanium dioxide core to be treated. For the hydrolyzable silicon compound, it is generally between 0.2 to 1.5% by weight, expressed as SiO 2 , relative to the titanium dioxide core to be treated.
Afin d'obtenir la précipitation du coprécipité de phosphate et de silice, on effectue habituellement cette étape à un pH compris entre 6 et 9. Le pH peut être contrôlé par l'ajout d'acide phosphorique et /ou d'un autre acide tel que l'acide sulfurique ou l'acide chlorhydrique. Le pH peut aussi être contrôlé par l'introduction simultanée et/ou alternative du composé à base de phosphore et du composé du silicium qui vont former le coprécipité. C'est le cas par exemple lorsqu'on utilise, lors de cette coprécipitation, de l'acide phosphorique et du silicate de sodium.In order to obtain the precipitation of the phosphate and silica coprecipitate, this step is usually carried out at a pH between 6 and 9. The pH can be controlled by adding phosphoric acid and / or another acid such as than sulfuric acid or hydrochloric acid. The pH can also be controlled by the simultaneous and / or alternative introduction of the phosphorus-based compound and the silicon compound which will form the coprecipitate. This is the case, for example, when phosphoric acid and sodium silicate are used during this coprecipitation.
Les quantités de composés du phosphore et du silicium introduites sont modulées de manière à précipiter une couche de coprécipité présentant un rapport atomique P/Si compris entre 0,3 et 3, de préférence entre 0,6 et 1 ,2.The quantities of phosphorus and silicon compounds introduced are modulated so as to precipitate a coprecipitate layer having a P / Si atomic ratio of between 0.3 and 3, preferably between 0.6 and 1, 2.
Si un dispersant à base de phosphate a été utilisé pour stabiliser la dispersion de pigment de dioxyde de titane de départ, on retranche la quantité de phosphate apportée par le dispersant à la quantité de phosphate introduite lors de la troisième étape de précipitation.If a phosphate-based dispersant was used to stabilize the dispersion of starting titanium dioxide pigment, the amount of phosphate provided by the dispersant is subtracted from the amount of phosphate introduced during the third precipitation step.
De manière avantageuse, on introduit successivement dans la suspension aqueuse de pigment de dioxyde de titane le composé du phosphore, puis le composé du silicium.Advantageously, the phosphorus compound and then the silicon compound are successively introduced into the aqueous suspension of titanium dioxide pigment.
La quatrième étape consiste à déposer une couche d'alumine. On entend, ici et pour toute la description, par couche d'alumine un précipité d'oxyhydroxyde d'aluminium.The fourth step is to deposit a layer of alumina. The term alumina layer is understood here and throughout the description to be a precipitate of aluminum oxyhydroxide.
Habituellement, on précipite cette dernière couche à partir d'un composé hydrolysable de l'aluminium tel que des sels hydroxylés basiques, on peut en particulier choisir l'aluminate de soude, le chlorure basique d'aluminium, l'hydroxyde d'aluminium diacétate. On peut aussi utiliser le sulfate d'alumine.Usually, this last layer is precipitated from a hydrolyzable aluminum compound such as basic hydroxylated salts. in particular choose the sodium aluminate, the basic aluminum chloride, the aluminum hydroxide diacetate. Alumina sulfate can also be used.
La quantité de composé hydrolysable de l'aluminium introduite au cours de cette étape est habituellement comprise entre 1 et 5 % exprimé en poids d'AI2O3 par rapport au poids du noyau de dioxyde de titane à traiter, de préférence entre 2 % et 4 %.The amount of hydrolyzable aluminum compound introduced during this step is usually between 1 and 5% expressed by weight of AI 2 O 3 relative to the weight of the titanium dioxide core to be treated, preferably between 2% and 4%.
Cette précipitation se fait au pH nécessaire à la précipitation de la couche d'alumine. Ce pH peut être compris entre 3 et 10. De préférence, ce pH est compris entre 5 et 10. La régulation peut être effectuée par l'ajout d'acide sulfurique.This precipitation takes place at the pH necessary for the precipitation of the alumina layer. This pH can be between 3 and 10. Preferably, this pH is between 5 and 10. The regulation can be carried out by adding sulfuric acid.
Après chaque étape de précipitation, on peut effectuer des étapes de mûrissement. Ces dernières consistent à agiter le mélange réactionnel suite à l'introduction des composés hydrolysables permettant la précipitation. De préférence, le temps de mûrissement est de l'ordre de 5 à 30 mn à chaque étape.After each precipitation stage, ripening stages can be carried out. The latter consist in stirring the reaction mixture following the introduction of the hydrolysable compounds allowing precipitation. Preferably, the ripening time is of the order of 5 to 30 minutes at each stage.
Suite à ces étapes de précipitation, les pigments sont séparés de la phase liquide de la suspension par tout moyen connu, par exemple par filtration. Puis le pigment est généralement lavé à l'eau, séché et micronisé.Following these precipitation steps, the pigments are separated from the liquid phase of the suspension by any known means, for example by filtration. Then the pigment is generally washed with water, dried and micronized.
Les pigments selon l'invention peuvent en outre être traités par des composés organiques afin de leur conférer des propriétés spécifiques à leur utilisation telles que brillance, dispersibilité, mouillage, stabilisation. Ces composés organiques peuvent être choisis parmi les polyols liquides ou solides tels que les polyglycols de faible masse moléculaire éthoxylés ou non, le triméthylolpropane (TMP), le triméthyloléthane (TME), le triméthylolpropane éthoxylé, les polyphosphates liquides, les hydroxyamines telles que la triéthanolamine (TEA), le 2-amino-2-méthyl-1- propanol (AMP) ou encore des produits à base de silicone. Ce traitement organique peut être réalisé en phase aqueuse après la quatrième étape de précipitation, ou après séchage des pigments.The pigments according to the invention can also be treated with organic compounds in order to give them properties specific to their use, such as gloss, dispersibility, wetting, stabilization. These organic compounds can be chosen from liquid or solid polyols such as low molecular weight polyglycols ethoxylated or not, trimethylolpropane (TMP), trimethylolethane (TME), ethoxylated trimethylolpropane, liquid polyphosphates, hydroxyamines such as triethanolamine (TEA), 2-amino-2-methyl-1-propanol (AMP) or silicone products. This organic treatment can be carried out in the aqueous phase after the fourth precipitation step, or after the pigments have dried.
L'invention concerne enfin l'utilisation des pigments selon l'invention dans les compositions de revêtement, notamment de peinture, ainsi que dans les compositions de plastiques pour lesquelles le pigment selon l'invention évite le bleuissement avec le temps.The invention finally relates to the use of pigments according to the invention in coating compositions, in particular paint, as well as in plastic compositions for which the pigment according to the invention avoids blueing over time.
Les pigments selon l'invention peuvent également être utilisés dans les lamifiés de papier. Les exemples suivants illustrent l'invention sans toutefois en limiter la portée.The pigments according to the invention can also be used in laminates of paper. The following examples illustrate the invention without, however, limiting its scope.
EXEMPLESEXAMPLES
Préparation d'un pigment selon l'inventionPreparation of a pigment according to the invention
On part d'une suspension de dioxyde de titane de concentration de 900 g/1. Elle a été broyée en présence de 0,2% en poids d'aminométhylpropanol (AMP90) par rapport au poids du dioxyde de titane, puis diluée à 350 g/l.The starting point is a suspension of titanium dioxide with a concentration of 900 g / l. It was ground in the presence of 0.2% by weight of aminomethylpropanol (AMP90) relative to the weight of titanium dioxide, then diluted to 350 g / l.
Elle est chauffée à une température de l'ordre de 80°C, puis le chauffage est coupé.It is heated to a temperature of the order of 80 ° C., then the heating is switched off.
Première couche. Le pH de la dispersion est ajusté à 5 par l'ajout d'acide sulfurique.First layer. The pH of the dispersion is adjusted to 5 by the addition of sulfuric acid.
On ajoute à la dispersion 1 ,1 % en poids de ZrO2, par rapport au poids de dioxyde de titane à traiter, sous la forme d'une solution de sulfate acide de zirconium. Cette addition est réalisée en 7 min. Le pH est régulé pendant l'addition par ajout de soude entre 4,8 et 5,2. Suite à cela, le mélange réactionnel est agité pendant 10 min.1.1% by weight of ZrO 2 , based on the weight of titanium dioxide to be treated, is added to the dispersion, in the form of a solution of zirconium acid sulfate. This addition is carried out in 7 min. The pH is regulated during the addition by adding sodium hydroxide between 4.8 and 5.2. Following this, the reaction mixture is stirred for 10 min.
Deuxième couche.Second layer.
On ajoute au milieu réactionnel précédent 0,15 % en poids de TiO2, par rapport au poids de dioxyde de titane à traiter, sous forme d'une solution d'oxychlorure de titane.0.15% by weight of TiO 2 , relative to the weight of titanium dioxide to be treated, is added to the preceding reaction medium, in the form of a solution of titanium oxychloride.
Cette addition est réalisée en 5 min. Durant celle-ci, le pH est maintenu entre 4,8 et 5,2 par ajout de soude.This addition is carried out in 5 min. During this, the pH is maintained between 4.8 and 5.2 by adding sodium hydroxide.
Suite à cela, le mélange réactionnel est agité pendant 15 min.Following this, the reaction mixture is stirred for 15 min.
Troisième coucheThird layer
On ajoute au milieu réactionnel précédent :The following reaction medium is added:
- 0,4 % en poids de P2O5, par rapport au poids de dioxyde de titane à traiter, sous forme d'une solution d'hexamétaphosphate de sodium,- 0.4% by weight of P 2 O 5 , relative to the weight of titanium dioxide to be treated, in the form of a solution of sodium hexametaphosphate,
- 0,7 % en poids de SiO2, par rapport au poids de dioxyde de titane à traiter, sous forme d'une solution de silicate de sodium.- 0.7% by weight of SiO 2 , relative to the weight of titanium dioxide to be treated, in the form of a sodium silicate solution.
Ces additions sont réalisées en 10 min. Durant celles-ci, le pH est maintenu entre 7,8 et 8,2 par ajout d'acide sulfurique.These additions are carried out in 10 min. During these, the pH is maintained between 7.8 and 8.2 by adding sulfuric acid.
Suite à cela, le mélange réactionnel est agité pendant 10 min. Quatrième coucheFollowing this, the reaction mixture is stirred for 10 min. Fourth layer
Le pH est ajusté à 9,5 par de la soude.The pH is adjusted to 9.5 with sodium hydroxide.
On ajoute au milieu réactionnel précédent 3,1 %, par rapport au poids de dioxyde de titane à traiter, en poids d'AI2O3 sous forme d'une solution d'aluminate de sodium. Cette addition est réalisée en 10 min. Durant celle-ci, le pH est maintenu entre 9,3 et 9,7 par ajout d'acide sulfurique.3.1% is added to the preceding reaction medium, relative to the weight of titanium dioxide to be treated, by weight of AI 2 O 3 in the form of a sodium aluminate solution. This addition is carried out in 10 min. During this, the pH is maintained between 9.3 and 9.7 by adding sulfuric acid.
Suite à cela, le mélange réactionnel est agité pendant 30 min.Following this, the reaction mixture is stirred for 30 min.
La dispersion est ensuite filtrée.The dispersion is then filtered.
Les pigments de dioxyde de titane obtenus sont lavés par de l'eau à 45°C, séchés à 150°C pendant 15 heures.The titanium dioxide pigments obtained are washed with water at 45 ° C, dried at 150 ° C for 15 hours.
Ils sont ensuite traités en surface par du triméthylolpropane à raison de 0,5 % en poids par rapport au poids de dioxyde de titane à traiter.They are then surface treated with trimethylolpropane in an amount of 0.5% by weight relative to the weight of titanium dioxide to be treated.
Pigments comparatifsComparative pigments
On utilise trois pigments du commerce présentant les caractéristiques suivantes :Three commercial pigments with the following characteristics are used:
- pigment comparatif 1 : pigment de dioxyde de titane recouvert d'un traitement de surface à base de 2,8 % en poids dΑI2O3 et 0,8 % en poids de ZrO2,- comparative pigment 1: titanium dioxide pigment covered with a surface treatment based on 2.8% by weight of I 2 O 3 and 0.8% by weight of ZrO 2 ,
- pigment comparatif 2 : pigment de dioxyde de titane recouvert d'un traitement de surface à base de 3,5 % en poids d'AI2O3, 0,6 % en poids de ZrO2 et 0,6 % en poids de P2O5,- comparative pigment 2: titanium dioxide pigment coated with a surface treatment based on 3.5% by weight of AI 2 O 3 , 0.6% by weight of ZrO 2 and 0.6% by weight of P 2 O 5 ,
- pigment comparatif 3 : pigment de dioxyde de titane recouvert d'un traitement de surface à base de 2,2 % en poids d'AI O3 et 5 % en poids de SiO2.- comparative pigment 3: titanium dioxide pigment covered with a surface treatment based on 2.2% by weight of AI O 3 and 5% by weight of SiO 2 .
Tests et résultats Les pigments sont testés en formulation de peinture pour extérieur.Tests and results The pigments are tested in exterior paint formulation.
Préparation des peinturesPaint preparation
On prépare quatre peintures à base des pigments définis ci-dessus. La peinture est à base d'un liant alkyde et d'une mélamine dans un ratio 70/30 en poids. Le taux de pigment est d'environ 37 % en poids.Four paints are prepared based on the pigments defined above. The paint is based on an alkyd binder and a melamine in a 70/30 ratio by weight. The pigment rate is around 37% by weight.
Ces peintures sont appliquées sur un support en aluminium, pour les mesures de farinage, ou sur un support en verre, pour les mesures de brillance, sur une épaisseur comprise entre 40 et 90 μm. Elles sont préséchées pendant 30 min, puis soumises à une cuisson à 130°C pendant 30 min.These paints are applied on an aluminum support, for chalking measurements, or on a glass support, for gloss measurements, over a thickness between 40 and 90 μm. They are pre-dried for 30 min, then baked at 130 ° C for 30 min.
Vieillissement accéléré On introduit les supports en aluminium enduits de peinture dans un appareil à vieillissement accéléré QUVB. Le cycle de vieillissement est le suivant :Accelerated aging The aluminum supports coated with paint are introduced into an accelerated aging device QUVB. The aging cycle is as follows:
- 4 heures d'UV à une température de 60°C, puis- 4 hours of UV at a temperature of 60 ° C, then
- 4 heures en présence d'humidité à une température de 50°C.- 4 hours in the presence of humidity at a temperature of 50 ° C.
MesuresMeasures
En fonction du vieillissement, on mesure sur les différents supports enduits:Depending on the aging, we measure on the different coated supports:
- la brillance à 20° à l'aide d'un brillancemètre,- 20 ° gloss using a gloss meter,
- le farinage Helmen sur des supports en aluminium. Pour réaliser la mesure de farinage Helmen, on colle puis décolle une bande adhésive sur une partie de la surface du support vieilli. On mesure ensuite la densité optique de ce ruban adhésif qui a été appliqué sur la peinture vieillie et qui a emporté une partie du farinage . La mesure de farinage correspond au rapport en pourcentage de cette densité optique sur celle mesurée pour le ruban adhésif propre avant collage. Cette mesure est lue directement à l'aide d'un appareil Helmen. Plus cette valeur est grande, plus le farinage est élevé.- Helmen chalking on aluminum supports. To carry out the Helmen chalking measurement, an adhesive strip is then glued onto a part of the surface of the aged support. We then measure the optical density of this adhesive tape which has been applied to aged paint and which has washed away some of the chalking. The chalking measurement corresponds to the percentage ratio of this optical density to that measured for the clean adhesive tape before bonding. This measurement is read directly using a Helmen device. The higher this value, the higher the chalking.
RésultatsResults
Le farinage de la peinture atteint une valeur de saturation de 80 % :The chalking of the paint reaches a saturation value of 80%:
- au bout de 1000 cycles QUVB pour le pigment selon l'invention, - au bout de 875 cycles QUVB pour le pigment comparatif 1 ,- after 1000 QUVB cycles for the pigment according to the invention, - after 875 QUVB cycles for comparative pigment 1,
- au bout de 585 cycles QUVB pour le pigment comparatif 2,- after 585 QUVB cycles for comparative pigment 2,
- au bout de 875 cycles QUVB pour le. pigment comparatif 3.- after 875 QUVB cycles for the . comparative pigment 3.
Après 120 cycles de vieillissement, la brillance de la peinture est de : - 66 pour le pigment selon l'invention,After 120 aging cycles, the gloss of the paint is: - 66 for the pigment according to the invention,
- 60 pour le pigment comparatif 1 ,- 60 for comparative pigment 1,
- 66 pour le pigment comparatif 2,- 66 for comparative pigment 2,
- 62 pour le pigment comparatif 3.- 62 for comparative pigment 3.
On observe que la formulation spécifique du traitement minéral selon l'invention assure à la peinture une plus lente apparition du farinage et une rétention de brillant au moins aussi élevée que pour les traitements comparatifs. It is observed that the specific formulation of the mineral treatment according to the invention provides the paint with a slower appearance of chalking and a gloss retention at least as high as for the comparative treatments.

Claims

REVENDICATIONS
1. Pigment de dioxyde de titane, caractérisé en ce qu'il comprend un noyau de dioxyde de titane recouvert successivement d'une couche d'hydroxyde ou d'oxyhydroxyde de zirconium, puis d'une couche de d'hydroxyde ou d'oxyhydroxyde de titane, puis d'une couche d'un coprécipité de phosphate et de silice et enfin d'une couche d'oxyhydroxyde d'aluminium.1. Titanium dioxide pigment, characterized in that it comprises a core of titanium dioxide successively covered with a layer of zirconium hydroxide or oxyhydroxide, then with a layer of hydroxide or oxyhydroxide titanium, then a layer of a phosphate and silica coprecipitate and finally a layer of aluminum oxyhydroxide.
2. Pigment selon la revendication précédente, caractérisé en ce qu'il est recouvert de : - 0,5 à 1 ,5 % en poids d'hydroxyde ou d'oxyhydroxyde de zirconium; exprimé en ZrO2,2. Pigment according to the preceding claim, characterized in that it is covered with: - 0.5 to 1.5% by weight of zirconium hydroxide or oxyhydroxide; expressed in ZrO 2 ,
- 0,05 à 1 % en poids d'hydroxyde ou d'oxyhydroxyde de titane, exprimé en TiO2,- 0.05 to 1% by weight of titanium hydroxide or oxyhydroxide, expressed as TiO 2 ,
- 0,2 à 1 ,5 % en poids de phosphate, exprimé en P2O5,0.2 to 1.5% by weight of phosphate, expressed as P 2 O 5 ,
- 0,2 à 1 ,5 % en poids de silice, exprimé en SiO2,0.2 to 1.5% by weight of silica, expressed as SiO 2 ,
- 2 à 4 % en poids d'oxyhydroxyde d'aluminium, exprimé en AI2O3, les pourcentages étant exprimés en poids par rapport au noyau de dioxyde de titane.- 2 to 4% by weight of aluminum oxyhydroxide, expressed as Al 2 O 3 , the percentages being expressed by weight relative to the titanium dioxide core.
3. Procédé de traitement de surface d'un pigment de dioxyde de titane, caractérisé en ce qu'il comprend les étapes suivantes :3. Method for surface treatment of a titanium dioxide pigment, characterized in that it comprises the following steps:
- on forme une suspension aqueuse de pigments de dioxyde de titane, - dans une première étape, on précipite une couche d'hydroxyde ou d'oxyhydroxyde de zirconium à la surface du pigment,an aqueous suspension of titanium dioxide pigments is formed, in a first step, a layer of zirconium hydroxide or oxyhydroxide is precipitated on the surface of the pigment,
- dans une deuxième étape, on précipite une couche d'hydroxyde ou d'oxyhydroxyde de titane à la surface du pigment,- in a second step, a layer of titanium hydroxide or oxyhydroxide is precipitated on the surface of the pigment,
- dans une troisième étape, on précipite une couche d'un coprécipité de phosphate et de silice à la surface du pigment,in a third step, a layer of a phosphate and silica coprecipitate is precipitated on the surface of the pigment,
- dans une quatrième étape, on précipite une couche d'oxyhydroxyde d'aluminium à la surface du pigment,- in a fourth step, a layer of aluminum oxyhydroxide is precipitated on the surface of the pigment,
- on récupère le pigment à partir de la suspension.- the pigment is recovered from the suspension.
4. Procédé selon la revendication précédente, caractérisé en ce qu'on effectue le traitement à une température supérieure à 60 °C.4. Method according to the preceding claim, characterized in that the treatment is carried out at a temperature above 60 ° C.
5. Procédé selon la quelconque de revendications 3 ou 4, caractérisé en ce qu'au cours de la première étape, on précipite une couche d'hydroxyde ou d'oxyhydroxyde de zirconium à partir d'un composé hydrolysable du zirconium choisi parmi le sulfate de zirconium, l'orthosulfate de zirconium, le chlorure de zirconium ou l'oxychlorure de zirconium. 5. Method according to any one of claims 3 or 4, characterized in that during the first step, a layer of zirconium hydroxide or oxyhydroxide is precipitated from a hydrolyzable compound of zirconium chosen from sulphate zirconium, zirconium orthosulfate, zirconium chloride or zirconium oxychloride.
6. Procédé selon l'une quelconque de revendications 3 à 5, caractérisé en ce qu'au cours de la première étape, on introduit entre 0,5 et 1,5 % en poids d'un composé hydrolysable du zirconium, exprimé en ZrO2, par rapport au noyau de dioxyde de titane.6. Method according to any one of claims 3 to 5, characterized in that during the first step, between 0.5 and 1.5% by weight of a hydrolyzable zirconium compound, expressed as ZrO, is introduced. 2 , with respect to the titanium dioxide core.
7. Procédé selon l'une quelconque de revendications 3 à 6, caractérisé en ce qu'au cours de la deuxième étape, on précipite une couche d'hydroxyde ou d'oxyhydroxyde de titane à partir d'un composé hydrolysable du titane choisi parmi le chlorure de titane, l'oxychlorure de titane ou le sulfate de titane.7. Method according to any one of claims 3 to 6, characterized in that during the second step, a layer of titanium hydroxide or oxyhydroxide is precipitated from a hydrolyzable titanium compound chosen from titanium chloride, titanium oxychloride or titanium sulfate.
8. Procédé selon l'une quelconque de revendications 3 à 7, caractérisé en ce qu'au cours de la deuxième étape, on introduit entre 0,05 et 1 % en poids d'un composé hydrolysable du titane, exprimé en TiO2, par rapport au noyau de dioxyde de titane.8. Method according to any one of claims 3 to 7, characterized in that during the second step, between 0.05 and 1% by weight of a hydrolyzable titanium compound, expressed as TiO 2 , is introduced, with respect to the titanium dioxide core.
9. Procédé selon l'une quelconque de revendications 3 à 8, caractérisé en ce qu'on effectue les deux premières étapes à un pH compris entre 4 et 6.9. Method according to any one of claims 3 to 8, characterized in that the first two steps are carried out at a pH between 4 and 6.
10. Procédé selon l'une quelconque de revendications 3 à 9, caractérisé en ce qu'au cours de la troisième étape, on précipite une couche d'un coprécipité de phosphate et de silice à partir de composés hydrolysables du phosphore et du silicium choisis parmi : - l'acide phosphorique, les phosphates tels que le tétrapyrophosphate de potassium ou de sodium, l'hexamétaphosphate de potassium ou de sodium, le tripolyphosphate de potassium ou de sodium, le dihydrogénophosphate de sodium, et - les silicates de sodium ou de potassium.10. Method according to any one of claims 3 to 9, characterized in that during the third step, a layer of a phosphate and silica coprecipitate is precipitated from hydrolysable compounds of phosphorus and silicon chosen among: - phosphoric acid, phosphates such as potassium or sodium tetrapyrophosphate, potassium or sodium hexametaphosphate, potassium or sodium tripolyphosphate, sodium dihydrogen phosphate, and - sodium or sodium silicates potassium.
11. Procédé selon l'une quelconque de revendications 3 à 10, caractérisé en ce qu'au cours de la troisième étape, on introduit entre 0,2 et 1,5 % en poids d'un composé hydrolysable du phosphore, exprimé en P2O5, par rapport au noyau de dioxyde de titane à traiter, et 0,2 à 1 ,5 % en poids d'un composé hydrolysable du silicium, exprimé en SiO2, par rapport au noyau de dioxyde de titane à traiter.11. Method according to any one of claims 3 to 10, characterized in that during the third step, between 0.2 and 1.5% by weight of a hydrolyzable phosphorus compound, expressed as P, is introduced. 2 O 5 , relative to the titanium dioxide core to be treated, and 0.2 to 1.5% by weight of a hydrolyzable silicon compound, expressed as SiO 2 , relative to the titanium dioxide core to be treated.
12. Procédé selon l'une quelconque de revendications 3 à 11 , caractérisé en ce qu'on effectue la troisième étape à un pH compris entre 6 et 9.12. Method according to any one of claims 3 to 11, characterized in that the third step is carried out at a pH between 6 and 9.
13. Procédé selon l'une quelconque de revendications 3 à 12, caractérisé en ce qu'au cours de la quatrième étape, on précipite une couche d'alumine à partir de composés hydrolysables de l'aluminium tels que les sels hydroxylés basiques. 13. Method according to any one of claims 3 to 12, characterized in that during the fourth step, an alumina layer is precipitated from hydrolysable aluminum compounds such as basic hydroxylated salts.
14. Procédé selon l'une quelconque de revendications 3 à 13 caractérisé en ce qu'au cours de la quatrième étape, on introduit entre 2,5 et 5 % en poids d'un composé hydrolysable de l'aluminium, exprimé en AI2O3, par rapport au noyau de dioxyde de titane.14. Method according to any one of claims 3 to 13 characterized in that during the fourth step, between 2.5 and 5% by weight of a hydrolyzable aluminum compound, expressed as Al 2, is introduced. O 3 , with respect to the titanium dioxide core.
15. Utilisation du pigment selon les revendications 1 ou 2 ou obtenu par le procédé selon les revendications 3 à 14 dans les compositions de peinture, les plastiques et les lamifiés de papier. 15. Use of the pigment according to claims 1 or 2 or obtained by the process according to claims 3 to 14 in paint compositions, plastics and paper laminates.
EP98903097A 1997-01-27 1998-01-20 Titania pigment, preparation and use Withdrawn EP0961814A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR9700821 1997-01-27
FR9700821A FR2758826B1 (en) 1997-01-27 1997-01-27 NOVEL TITANIUM DIOXIDE PIGMENT, PROCESS FOR PREPARING IT, AND USE THEREOF IN PAINT COMPOSITIONS
PCT/FR1998/000103 WO1998032803A1 (en) 1997-01-27 1998-01-20 Titania pigment, preparation and use

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US6200375B1 (en) 2001-03-13
ID22792A (en) 1999-12-09
WO1998032803A1 (en) 1998-07-30
NO993619D0 (en) 1999-07-26
HUP0002832A2 (en) 2000-12-28
KR20000070489A (en) 2000-11-25
CN1244888A (en) 2000-02-16
FR2758826A1 (en) 1998-07-31
BR9808891A (en) 2000-10-03
AU5993998A (en) 1998-08-18
NZ336866A (en) 2000-04-28
IL130878A0 (en) 2001-01-28
FR2758826B1 (en) 1999-04-16
BG103568A (en) 2000-11-30
NO993619L (en) 1999-09-20
TR199901753T2 (en) 1999-10-21
CA2277058A1 (en) 1998-07-30
PL334837A1 (en) 2000-03-27
SK99599A3 (en) 2000-07-11
JP2000513763A (en) 2000-10-17

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