WO2001074735A1

WO2001074735A1 - Process for producing pigment granules and for dyeing concrete

Info

Publication number: WO2001074735A1
Application number: PCT/CA2000/000346
Authority: WO
Inventors: Daniel Fortin; Marie-Paule Jacoulet; Axel E. Jungk; Mark Roberts
Original assignee: Axel J. Societe En Commandite
Priority date: 1999-03-15
Filing date: 2000-03-30
Publication date: 2001-10-11
Also published as: CA2263667A1; AU2000235473A1; CA2263667C

Abstract

Process for producing pigment granules comprising the following steps of: a) preparing a mixture, in the form of a liquid suspension, of an emulsion and/or of a paste, said mixture comprising at least one pigment and at least one binder selected from the group constituted by the organic compounds which form insoluble films after drying and/or by chemical reaction during the drying, each binder being selected so that the films thereby obtained are free of dispersing effect in concretes; and b) drying of said mixture. The granules obtained are resistant to humidity and are used for dyeing concretes.

Description

PROCESS FOR PRODUCING PIGMENT GRANULES AND FOR DYEING CONCRETE

FIELD OF THE INVENTION

The present invention relates to a process for producing pigment granules and to the granules obtained therefrom. The present invention also relates to a process for dyeing concrete and other materials with the granules obtained by the process according to the invention.

In the framework of the present invention, "granules" means agglomerates and aggregates of materials with an average diameter ranging from 30 μm to 2 mm, initially in a powder state, and/or in the state of a suspension and/or of a solution.

The expression "pigments " relates to organic and/or inorganic dyes, including white pigments as example such as titanium dioxide, the various red, yellow, brown and black iron oxides and their mixtures, carbon blacks, chromium oxide, manganese oxide and/or cobalt spinelles and others.

In the framework of the present invention, the term "concrete" relates to the raw material which contains among other things, before any chemical reacting: cement or other hydraulic binders, and/or fly ashes, silicates, sands and/or aggregates and other components, for example for producing plates, tiles, paving stones, interlocking paving stones, parpens, and for the realization of concrete binding for example. Moreover the term "concrete" also covers mortar or cement, fibre-cement compounds and other articles initially containing cement and/or hydraulic binders.

Concrete is a well-proven material in construction, which in its form of decorative concrete, also satisfies aesthetic requirements. The dyeing of the concrete mass for producing decorative concrete provides the latter with a long- lasting tint, requiring nearly no maintenance for years. On the other hand, concrete surfaces, decorated by the application of a paint coating, need to be repainted at short intervals. Colored concrete is used for example for facades, plates, cobblestones, tiles, anti-noise embankments, retaining walls, dikes, bridges and similar constructions, and in the form of colored mortar and of roughcast, also for decorating facades.

Concrete is colored by inorganic pigments and more recently by organic pigments. For example, manganese oxide, iron oxide, chromium oxide, and carbon have proved to be suitable pigments for concrete application. More particularly, pigments made of carbon, and iron oxide, appeared to be very efficient in practice.

The producing of colored concrete nevertheless gives rise to the following problems. The powder of pigments produces dust and its use soils humans, machines and premises.

Due to the fineness of the particles, pigments stocked in silos loose very quickly their fluidity. It is then very difficult to extract them from the silos, with very high costs in machines and human labor.

For the same reasons, their metering by screw conveyor, and vibrating grooves, is very difficult.

STATE OF THE ART

Known in the prior art, attempts have been made to resolve the problem associated with the use of powdered pigments, i.e. the appearance of dust during stockage notably in silos (ensilage) and during the automatic metering, by using aqueous pigment pastes for the dyeing of concrete. Most of the time, this type of pastes contains about 30 to 70% of water as a carrying mixture as well as tensioactive products. The advantages resulting from the use of aqueous pigment pastes as compared to pigment powders are nevertheless accompanied by major drawbacks.

In practice, the pastes cannot be stocked for very long in the silos or in other greatly dimensioned containers since they separate by segregation of the components and result partially in solid deposits.

Due to the high content in water, the packaging costs are twice as high for aqueous pigments pastes and likewise for transportation costs for the "water" part present in those pastes. Another drawback comes from the fact that the pastes of this type are not usable when the own humidity of the sand and of the aggregates used for preparing concrete is such that any addition of water, even in the form of aqueous pigments pastes, degrades the consistency of the concrete in an intolerable manner; this situation arises very frequently in open building sites. Moreover, surfactants and dispersants used in these pastes very often increase efflorescence of the colored concrete.

In the field of coloring lacquers and synthetic materials, the above- mentioned drawbacks have been minimized by using pigments in the form of granules and not in the form of pastes or powders.

Thus, and especially in the industry of synthetic materials, pigments which are harmful have been used for many years, nearly exclusively, in the form of granules.

The production and the use of granules are now well-known in various fields of the human industry (see H.Rumpf in "Chemie-lng-.Technik", 30, 1958, n° 3, n°4, n°5; W.C. Peck in Chemistry and Industry", delivery of 20.12.1958, pp. 1674 and following; concerning the granulation by fusion, see U.A.W. Boretzky in "Fette-,

Seifen-, Anstrichmittel", n°4, 1967).

Thus, briquettes have dominated in the field of coal and minerals. For carbon paper, micro-capsules are used. In the field of agriculture, the fodder is stocked in silos, in the form of compact granules. In the field of lacquers, concentrates of pigments in nitrocellulose are used, free of dust which are dissolved perfectly in solvents. In the field of rubber, carbon black is used in the form of granules obtained by aggregation. PCV is used in the form of pearled granules obtained by atomisation and by drying of its aqueous suspensions.

The dyeing of concrete by pigments in the form of granules is also part of the state of the art.

Patent No. FR-A-2,450,273 describes pearled granules containing pigments made of dry carbon, but at the same time, with a water content of 59%, with little dust. These granules are used for dyeing cement.

European Patent No. EP-A-0, 268,645 and its equivalents in the United States (US-A-4,946,505) and in Canada (CA-A-1 ,291 ,849) describe the coloring of concrete with the help of pigment granules, except for compacted or "briquetted" granules, which are made of one or more pigments, pure carbon pigments being excluded, and obligatorily, with the help of one or more binders, which promote the dispersing of the pigments in the concrete. The specific binders described in this document are well defined. In comparison to concretes colored with pure pigments and without additives, they can generate an increase of the efflorescence in concrete.

Since all these binders present in the mentioned granules are easily soluble in water, the influence of atmospheric humidity is critical. Particularly, in concrete factories, which are close to steam chambers, the humidity dissolves these binders and generates significant agglomeration of these granules, and the subsequent formation of hard balls during storage of the granules even during their use. These balls cannot disperse in concrete and they block the metering equipment.

Moreover, the patent EP-A-0,268,645 teaches that : the use of pigment in the form of granules is disadvantageous, since the dispersion forces applied to the granules during the mixing of the different components in order to form the colored concrete are insufficient and lead to the formation of pigment stains and of pigment nests close to the concrete surface thus colored,

pigments in the form of granules exhibit an insufficient dispersion, lack tinting strength and, in order to reach the same result, need to be applied in a higher amount than powder,

pigments in the form of granules which contain a binder do not show improved dispersing effects, and finally,

the humidity present in the concrete is not sufficient for dissolving granules which contain a binder.

According to patents No. DE-4,336,613-C1 and No. US-A-5,484,481 of "Bayer AG, Leverkusen DE", it is possible to produce and to use granules for dyeing concrete, by preparing a mixture of different inorganic pigments with at least one binder, most of these being already mentioned in the patent No. US-A-4,946,505, by forming a cohesive powder and by producing by compaction under specific conditions of controlled pressure, flakes, which are later ground and granulated by agglomeration. The drawbacks of these granules lie in their high mechanical instability and in the formation of powder-like products and of dust; the granules according to this process are not free flowing and are not suited for automatic measuring by usual simple systems.

Moreover, the granules of pigment obtained according to this complicated process present no advantage when compared to the granules obtained by the process according to the patent No. US-A-4,496,505.

European patent No. EP-B-0, 802,241 of the Bayer AG company describes a granulation process, similar to the above mentioned compacting process, for the carbon black pigment, with the same drawbacks. European patent No. EP-B-0,697,379 describes, in general terms, the formation of granules in a "fluid bed dryer". The patent No. EP-A-0,657,511 describes a particular form of the patent No. US-4,496,505 by using as binders sugars which belong to the family of polyhydroxy substances described in the patent No. US-A-4,495,505 even though the sugars used are known to modify the properties of concretes in a negative way.

The patent No. DE-A-4,223,598-A1 describes a particular form of the patent No. US-A-4,496,505 by offering polyphosphates as binders, which promote the dispersing of pigments in concrete. At the same time these granules are not free flowing and still exhibit a high abrasion, and with this, a lot of dust.

European patent No. EP-A-0,518,152 uses soluble salts as binders for granules and as an agent which promotes the dispersion of pigments in the concrete. But, since these granules are also not mechanically stable, they still bring a lot of dust and they are not free flowing.

European patent No. EP-A-0,507,046 describes granules for coloring concrete with the "advantage" of a supplementary agglomeration step of the granules, once that these granules have been prepared according to the spray granulation process. Moreover, this process does not bring satisfying results regarding the free flowing of these granules, the absence of dust and the simplicity of the process. In fact, it is a more complicated version of the process described in the patent No. EP-A-0,482,450 which uses certain salts as binders in a process of granulation by agglomeration, without a spray granulation step being required.

European patent No. EP-B-0,482,449 describes granules of inorganic pigments, which contain impurities already present in the pigments from their production process, i.e. the inorganic salts. This patent claims any process for dyeing concrete with granules, already described in the prior art and containing pigments (iron oxide). In practice, the granules according to this patent exhibit the same drawbacks as the granules of the preceding patent with respect to the problems related to the dust and to the lack of free flow. The patent No. EP-B-0,395,872 describes granules of black iron oxide, made by spray granulation of an aqueous suspension of this oxide with an unstable organic substance, which in practice works like a dispersing agent for the preparation of the aqueous suspension with a high content in pigments (50-75%), as already described in the patent No. US-A-4,946,505; after granulation the dispersant is destroyed by an additional thermal process, which has to be applied after the spray granulation at very high temperatures.

Out of all these processes, only the process described in the patent No. EP-A-0,268,645 has reached an important commercial success, despite its drawbacks.

OBJECT AND SUMMARY OF THE INVENTION

The three main objects of the present invention are:

a) a new, simple and modern process, allowing the production of pigment granules free of the drawbacks of the granules of the state of the art;

b) a process allowing the dyeing of concrete but also that of plastics and paints with the help of these new pigment granules; and

c) new non hygroscopic pigment granules, free of dust, flowing freely, and which do not form agglomerates due the presence of humidity, allowing an easy automatic handling and dispersing well in the material to be dyed.

The granules according to the invention are free of dust, free flowing, non hygroscopic and do not form agglomerates due to the presence of humidity. Moreover, these new granules, despite the prejudices mentioned in lines 23 to 52, column 2 of the patent No. US-A-4,946,505, disperse well in concrete with the same tinting strength as that of the granules of the patent No. US-A-4,946,505, as that of the corresponding pigments in form of powder and are well dispersed in the medium to be dyed. Moreover, the granules according to the invention exhibit an additional advantage when compared to those containing dispersants, in the sense that they do not negatively influence the mechanical elimination of water in wet concretes.

Moreover, the granules according to the invention are, except for impurities, free of dispersants and/or surfactants or of other chemical compounds soluble in water, as it is the case, among other things, for those granules described in the patent No. US-A-4,495,505, which contain binders allowing promotion of the dispersion of granules into concrete.

This feature is of particular importance because the additives soluble in water promotes efflorescence of colored concrete and often influence in a negative way the hardening of concrete. Such additives are disadvantageous for the material to be dyed, particularly for concrete.

On the contrary, the granules according to the invention are free of dispersing binders that are soluble in water, they avoid the promotion of efflorescence in concrete and the formation of hard balls, during their storage under the influence of humidity, balls insoluble in concrete. The insoluble and inactive binders contained in the granules according to the invention neither exhibit the negative effects generated by the additives of the prior art upon the hardening of the concrete.

The first object of the present invention is reached by the process for producing pigment granules comprising the following steps of:

a) preparing a mixture, in the form of a liquid suspension, of an emulsion and/or of a paste, the said mixture comprising at least one pigment, and at least one binder selected from the group consisting of the organic compounds which form insoluble films after drying and/or by chemical reaction accompanying the drying, each binder being selected such that the films thereby obtained are free of dispersing effects in concretes; and b) drying of said mixture.

The second object of the present invention is reached by a process for dyeing concrete using as dyes granular pigments obtained by the process according to the first object of the invention as dyes.

The third object of the present invention is reached by pigment granules comprising:

less than 20% of water;

from 79 to 99.95% of pigment;

from 0.05 to 15% of binders selected from the group consisting of organic compounds which form insoluble films after drying and/or by chemical reaction accompanying the drying, said binders being chosen such that the films thereby obtained are free of dispersing effects in concrete,

the percentages being weight percentages expressed with respect to the total weight of pigment granules.

Preferably, the pigment granules according to the invention, contain less than 4% of water and from 81 to 99.95% of pigments.

DETAILED DESCRIPTION OF THE INVENTION

Prior to preparation of pigment granules, a mixture, in the form of a liquid suspension, of an emulsion and/or of a paste is prepared, said mixture comprising at least one pigment and at least one organic binder of a specific nature.

The mixture eventually contains one or more additives for concretes.

Preferably, the liquid used for the preparation of the mixture is water.

The binders used in the preparation of the mixture are: organic compounds which form insoluble films after drying and/or by chemical reaction accompanying the drying, and more particularly

resins and/or systems of resins usable, for preparing varnishes and/or paints, preferably as binders,

each binder being selected such that the films thereby obtained are free of dispersing effects in concrete.

According to a preferred embodiment of the invention, the mixture additionally contains chemical additives which react with the binder during the drying of said mixture.

Preferred are binders which by drying and/or by chemical reaction and/or by the presence of reactive additives, become insoluble and form a film, stabilising the mechanical properties of the granules without affecting their coloring effect,

, said binders being further selected such that the films thereby obtained are free of dispersing effects in concretes.

According to a preferential embodiment of the invention, the binder used is selected from the group consisting of the polyacrylates, the copolymers of styrene and polyacrylic acids, the vinyl acrylates, the copolymers of styrene and of acrylates, the copolymers of maleic acid anhydride, and the latex used in paints such as those described in the following table:

Preferably, the binders are present in the form of a suspension or an aqueous emulsion.

According to another embodiment of the invention, resins or other chemical compounds are used as binders which form insoluble films in water during the drying by reacting with reactive additives.

According to a preferred embodiment of the invention, binders are used, that display a well developed dispersing capability. This allows to obtain mixtures made of liquid, preferably water, of pigments, of binders with a dispersing effect and of other additives with a very high volumetric concentration of pigments; these binders are used with reactive additives that by chemical reaction with one or more binders, particularly by reticulation, become insoluble in water and weather resistant and form films and stabilise the mechanical properties of granules without disturbing the coloring power.

^* Trade-mark Advantageously, the binder is selected from the group consisting of resins and systems of resins used for preparing varnishes and/or paints.

The binders, with a high dispersing capacity particularly well adapted for the formation of water insoluble films by a reticulation reaction with reactive additives, and free of dispersing effect in concrete, are polymer acids in their acid forms, the polymer acids in their partially neutralized form and the polymer acids in their neutralized form. More particularly, they are polycarboxylic and polyacrylate acids. As an example of polymer acids and polycarboxylic acids, the Carbopol^* and the BF-Goodrich "K^*-700 Series" in a partially neutralised state.

Can also be used volatile catalysts which are dispersant and surfactants.

As an example of polyacrylates, in their acidic or partially neutralized form such as the Rhom and Haas Acrysol* G-111 , or such as some polyacrylates sold by Allied Colloids, BASF.

Are also suitable organic binders with plasticizing and/or tensioactive properties before drying, but not after drying.

If it appears necessary, it is possible to additionally use other binders which are not disturbing for concrete.

The amount of binder present in the granules varies between 0.05 to 15% in weight with respect to the total weight of granules, preferably between 0.5 to 8% in weight and more particularly between 0.8 and 5% in weight.

The mixture contains in weight from 0.1 to 15% of binder with respect to the weight of pigments present in the mixture.

According to a preferred embodiment of the invention, each binder exhibits before drying, plasticizing and/or tensioactive effects and these properties are not present anymore after drying.

^* Trade-mark According to another embodiment of the invention, catalysts are used with the binders i.e. substances which, during the step of drying leading to granulation, are completely evaporated and potentially recuperated by cooling of vapours and recycled. These volatile catalysts have as a function to facilitate the dispersion of pigments in the liquid mixture and to reach a higher volumetric concentration of pigments in said mixture. This is important for the diameter of the obtainable granules, particularly during a drying granulation by atomisation, but also for the amount of liquid which is evaporated, in order to obtain a certain amount of granules, which is then reduced.

The amount of catalyst present in the mixture ranges from 0.1 to 15% in weight with respect to the weight of pigment present in the mixture.

These volatile catalysts allow to sensibly increase the amount of pigment in the mixtures containing pigments, binders and other additives. There are for example amino alcohols such as AMP, Surfynol 61 (secret mixture), Surfynol^* CT-171 , CT-111 , CT 121 and CT-131 , the acetylenic diols, the triethylamine, the T-Amine WR500*, the acetic acid, or any other dispersant which evaporates during the drying steps.

AMP is of particular interest as a volatile catalyst.

From an economically interesting point of view, the volatile catalyst is recovered during the drying step and recycled into the process. According to a preferred embodiment, the volatile catalyst is recovered by cooling.

The chemical reactive additives, which can also exhibit dispersing effects, and which react with said binders by forming insoluble films in water by reticulation during and/or by the drying step and which allow, to sensibly increase the amount of pigment in the mixtures comprising the pigments, binders and additives are, for example, polyols such as polyethylene glycols (Macol BASF)

Trade-mark and/or oligomers of the ethylene glycol, of propanediol, of butanediol, of pentanediol, of pentaerythrite, of trimethylolpropane, of α-Naphtolbenzein, of 2-(2-hydroxyethoxy)phenol, of 1 ,3-dihydroxyacetone dimer, of

1 ,8-dihydroxyantraquinone, of anthrarufin, of 3,5 dihydroxybenzoic acid, of 1 ,5-dihydroxynaphtalene, of 3-hydroxy-2,2-dimethylpropyl 3-hydroxy- 2,2-dimethylpropionate of acetylenes such as Surfinol^* 104, Surfinol^* 104 PG50, Surfinol* 104 DPM, Surfinol^* 104 E, Surfinol*104 BC, Surfinol* 400 Series (Air Products), glycol silicone (BASF Corp.), sugars and modified polyurethane such as EFKA* 452 of LUBRIZOL.

According to a preferred embodiment of the invention, the reactive chemical additives are used in an amount ranging from 0.1 to 15% with respect to the weight of pigments present in the mixture.

In certain cases, it is advantageous to add to the mentioned mixtures, a pH regulator in order to optimise the effects of the binders and of the additives. Examples of pH regulators are sodium acetate, carbonates, NaOH, ammonium salts and sulphuric acids.

According to another embodiment of the invention, the mixture containing preferably water, binders, optionally dispersive volatile catalysts and/or reactive chemical additives, and pigments, may contain one or more additives useful for concrete.

Pigment granules obtained according to one of the processes of the invention, are used for coloring concrete or other materials. They contain among other things, water, the above mentioned pigments, binders in the form of their films insoluble in water and, eventually, other additives useful for concrete.

The amount of volatile catalyst introduced in the mixture but missing in the granules ranges from 0 to 15% in weight with respect to the weight of a granule.

Trade-mark The amount of reactive additives and of reticulants introduced in the mixture before drying represents from 0 to 15% in weight of a granule.

The pigments used for preparing the mixture are of organic and/or inorganic nature. Among inorganic pigments are preferably selected, pigments from the group of the manganese oxides, iron oxides and hydroxides, chromium oxides, titanium dioxides, carbon blacks and spinelles, particularly cobalt spinelles. It is also possible to use exclusively organic, exclusively inorganic and mixtures of organic and inorganic pigments.

Well suited for the process of dyeing concrete according to the invention, are fine granules, with a size between 30 μ and 3 mm, preferably between 35 μ and 2 mm, more particularly between 40 and 500 micrometers and particularly suited are granules of a size between 40 μ and 400 μ obtained by drying and granulation of a mixture containing:

a) a phase, preferably water,

b) pigments such as those described above, and eventually other suitable additives,

c) the above-mentioned binders, and

d) eventually, catalysts such as those described above, and

e) eventually, the reactive substances described above for the reticulation of binders.

The pigment granules obtained contain:

less than 20% of water;

from 79 to 99.95% of pigment; and

from 0.05 to 15% of binders selected from the group consisting of the organic compounds which form insoluble films after drying and/or by chemical reaction accompanying the drying, the percentages being weight percentages expressed with respect to the total weight of the granule.

The pigment granules preferably contain less than 4% of water and from 79 to 99.95% of pigments.

Other granules representative of the invention contain:

less than 10% of water;

from 39.5 to 44.98% of pigment;

from 0.025 to 7.5% of binders selected from the group consisting of the organic compounds which form insoluble films after drying and/or by chemical reaction accompanying the drying; and

up to 50% of additives for concrete,

the percentages being weight percentages expressed with respect to the total weight of the granule.

The pigment granules obtained are preferably in the form of pearls.

The mixtures of pigment granules obtained by one of the processes of the invention contain at least 90% of pearls with a size ranging from 40 to 400 microns.

According to the state of the art, there is a multitude of different ways to produce pigment granules from mixtures in the form of a liquid suspension, of an emulsion and/or of a paste. The granules according to the invention may be obtained in different ways by drying a mixture of binders, pigments, liquid, preferably water, eventually volatile catalysts and/or reactive additives and, if needed, of other additives.

It is for example possible to apply on a drum a fine layer of such mixture in the form of a paste, which will be dried and then ground into very fine granules. It is also possible to apply a fine layer of this type of mixture in the form of a paste on a metallic drying band where the mixture will be dried, then ground into fine granules.

Another way to proceed consists in preparing the mixture and to extrude it with the help of an extruder according to the so called "spaghetti" or "angel hairs" process which is commonly used in the pasta food industry, then by drying it with warm air or by contact with a warm surface and by grinding the strings of

"spaghetti" thereby obtained.

Yet another way to produce granules according to the invention consists in applying very small drops of this mixture on a heated surface and to separate these small dried drops from the surface.

The preferred form for the granules according to the invention is the pearled granule.

Said pearled granules are obtained from mixtures of the liquids described above by an atomizer dryer via pipes having one or several nozzles at their end or respectively spray disks placed in a spray tower.

The pearled granules are in the form of micro granules; 90% of the pigment particles have a size ranging from 20 to 500 μ, particularly a size ranging from 40 to 400 μ.

It is surprising and in contrast to what is taught of the prior art, that the above-mentioned granules are well dissolved in concrete despite the fact that the dispersion of these granular pigments is carried out in the absence of binders which promote the dispersing of granules in concrete, as specified in the patent No. US-A-4,946,505.

Moreover, they disperse homogeneously to give a decorative concrete which is perfectly colored without stains or nests of color. Their use is also economical because with a determined amount of granulated pigments, one can obtain a coloring having an intensity similar to the intensity obtained with the same amount of powdered pigments. In comparison to a coloring with pure powder pigments, concrete colored with the granules according to the invention does not at all or at least does not exhibit or does not exhibit more efflorescence, and most of the time exhibits less efflorescence than when colored with the known granules containing dispersants as binders for stabilising the granules.

The granules produced and used according to the invention flow freely from a silo and do not tend to agglomerate nor to form agglomerates. They are easily transported by pneumatic means. At the same time, they have a lower sensibility to humidity and show less tendency for forming agglomerations or hard balls, than the granules containing water soluble dispersants or even hygroscopic dispersants as binders.

The handling of granules according to the invention produces practically no dust. From a handling point of view, the granules are superior to those of the prior art. Thus, producing and use of the granules according to the invention are therefore particularly suited for a clean and automatic dyeing, more particularly of concrete. Due to these facts, they are of excellent use in practice.

The invention will be illustrated in more detail with the help of the following examples.

Example 1

Production, according to the process of the invention, of pearled granules containing black iron oxide, Magnetite (FegOj)

A mixture in the form of a suspension made of 55.4% in weight of black iron oxide and of 1.6% in weight of a binder which was a copolymer of polyacrylic acid with styrene, of 0.6% of amino methyl propanol as volatile catalyst and of water for the rest, were dried with the help of compressed air by a drying device equipped with a spray nozzle by spraying at reversed flow. The inlet temperature ranged from 240° to 325°C and the outlet temperature of the air ranged from 115° to 130°C.

The product obtained was a pearled granule and 98% of the pearls had a size ranging from 45 μ to 375 μ.

Those granules were free flowing, were free of dust and had a residual humidity ranging from 0.3 to 1.3%. The bulk density ranged from 0.81 to 1.04 g/l.

The pearled granules thus obtained had an average size ranging from 150 to 200 μ and exhibited a good mechanical stability.

Example 2

Production of pearled granules according to the process of the invention from red iron oxide (Hematite)

From a mixture in the form of an aqueous suspension composed of: 0.9% of binder which is a copolymer of polyacrylic with styrene, 1.13% of amino methyl propanol as volatile catalyst, 60% of red iron oxide and of water for the rest, pearled granules were prepared in the same way as described in Example 1. The inlet temperature of the drying air ranged from 280° to 340°C; the outlet temperature of the air was between 110° and 170°C.

The granules obtained were raw, 78% of them had a size ranging from 355 μ to 45 μ, they were free flowing and were dust free. Their residual humidity ranged from 0.3 to 0.1% and the bulk density ranged from 0.800 to 1.100 g/l.

Example 3

Production of pearled granules according to the process of the invention, from yellow iron oxide (Goethite)

From a mixture in the form of an aqueous suspension composed of: 0.9% of binder, a copolymer of polyacrylic acid with styrene, 1.13% of amino methyl propanol as a volatile catalyst, 40% of yellow iron oxide and water for the remaining part, pearled granules were prepared in the same way as described in Example 1. The inlet temperature of the drying air ranged from 280° to 340°C, the outlet temperature of the air ranged from 110° to 170°C.

The obtained granules were raw, 78% of the grains had a size ranging from 355 μ to 45 μ, were free flowing and were dust free. Their residual humidity ranged from 0.3 to 2.9% and the bulk density ranged from 500 to 1.100 g/l.

Example 4

In a cement mixer (Masa type) with a volume of 1.25 m³, 1 ,024 kg of sand and of aggregates and 10.4 kg of black iron oxide in the form of pearled granules as obtained in Example 1 were mixed for 1.5 minutes. Then 183 kg of cement (artificial Portland) and the required amount of water with the help of an automate were added to the mixture and homogenised for 1.5 minutes. The cement mixer was then emptied and the mixture was used for producing concrete pavements.

Comparative Example 4a

The same procedure as described in Example 4 was used. Instead of pearled granules obtained according to the invention, the same amount of black iron oxide (10.4 kg) in the form of granules with a binder which promotes the dispersing of pigments in concrete, i.e. of Granufin Onyx^* of the Davis society, was used.

Then the shades of the humid concretes were compared and thereafter the shades of the pavements dried for 24 hours. In the humid concrete, no difference could be seen in the colors.

However, it could be seen that the dried concrete, colored with Granufin Onyx^* exhibited, at its surface, a thin milky layer which is typical of the efflorescence phenomenon.

Trade-mark Comparative example 4b

It is proceeded as described in Example 4. Instead of pearled granules obtained according to the invention, the same amount (10.4 kg) of black iron oxide in the form of powder (Bayferrox^* 330 of the society Bayer AG) was used.

Then the shades of the humid concrete were compared and thereafter the shades of pavements dried for 24 hours. Neither in the humid concrete nor in the dried concrete, could differences of color be seen.

Example 5

It is proceeded as described in Example 4. For coloring, red pearled granules according to Example 2 in an amount of 11.3 kg were used.

Comparative Example 5a

It is proceeded as described in Example 5. For coloring, 11.3 kg of pigments in the form of granules with a binder which promotes the dispersing of pigment in concrete, i.e. the Granufin Terracotta* (of the Davis society) was used.

Then the shades of the humid concretes obtained as in Example 5 were compared with those obtained as in Example 5a, and thereafter the shades of pavements dried for 24 hours.

Neither in the humid concrete, nor in the dried concrete, could differences of color be seen.

Comparative Example 5b

It is proceeded as described in Example 5. For coloring, 11.3 kg of pigments in a powder form used for producing granules according to Example 2 was used.

Trade-mark The shades of the humid concretes obtained in Example 5b were compared with those obtained in Example 5, and thereafter the shades of the pavements dried for 24 hours. Neither in the humid concrete, nor in the dried concrete, could differences of color be seen.

Example 6

It is proceeded as described in Example 5. For coloring, 11.3 kg of yellow pearled granules according to Example 3 were used.

Comparative Example 6a

It is proceeded as described in Example 5. For coloring, 11.3 kg of pigments in the form of granules with a binder which promotes the dispersing of the pigment into the concrete, i.e. of Granufin Maize* of the Davis society was used.

A comparison was made between the shades of the humid concretes obtained as in Example 6 with those obtained in Example 6a, and thereafter the shades of the pavements dried for 24 hours. Neither in the humid concrete, nor in the dried concrete, could differences of colors be seen.

Comparative Example 6b

It is proceeded as described in Example 5. For coloring, 11.3 kg of yellow powder pigments were used, the same powder used to produce granules according to Example 3.

The shades of the humid concretes obtained in Example 6 were compared with those obtained in Example 6b, and thereafter the shades of pavements dried for 24 hours. Neither in the humid concrete, neither in the dried concrete, could differences of color be seen.

* Trade-mark Example 7

An aqueous mixture of 150.00 ml of water, of 6.00 g of K-702^* as a reticulating binder, of 1.32 g of propylene glycol as reactive additive and of 1.50 g of AMP-95 as volatile catalyst was prepared; 0.44 g of NH₄OH (25%) was added in order to obtain a pH of 8, and thereafter 143 g of yellow pigment (Goethite).

With the help of a pipette, small drops of this mixture were placed on a glass plate and dried at 110°C. After drying, small pearls with a diameter of about 1 mm were obtained. 10 g of these pearls were put into water for 72 hours; they did not decompose.

Example 8

An aqueous mixture of 150.00 ml of water, of 10.00 g of K-702^* as a reticulating binder, of 2.19 g of propylene glycol as reactive additive and of 2.20 g of AMP-95 as a volatile catalyst was prepared; then 2.00 g of NH₄HCO₃ was added in order to obtain a pH of 8, and then 303 g of red pigment (Hematite) was added.

With the help of a pipette, this mixture was put in the form of small drops on a glass plate and dried at 110°C. After drying, small drops with a diameter of about 1 mm were obtained. 10 g of those pearls were put into water for 72 hours; they did not decompose.

Example 9

4.54 g of white sand and 3.5 g of yellow granules of the Example 7 were dry-mixed for 60 seconds in a 5 I container, with the help of a Hobarth type mixer. Then 140 g of white cement and 56 ml of water were added. The whole was further mixed for 2 minutes. The mortar obtained was poured into a square form with a depth of 3 cm. The form was conserved at ambient temperature for 24 hours. The body made of mortar was then removed from the mold.

^* Trade-mark Comparative Example 9a

4.540 g of white sand and 3.5 g of yellow granules containing a binder which promotes the dispersing of the pigment into concrete, i.e. the Granufin

Maize^* of the Davis Colors society, were dry-mixed for 60 seconds in a 5 I container with the help of a Hobarth type mixer. Then 140 g of white cement and

56 ml of water were added to the mixture.

The whole was further mixed for 2 minutes, then the mortar obtained was poured into a 3 cm deep square form. The form was conserved at ambient temperature for 24 hours.

Then the body made of mortar was extracted from the form.

Comparative Example 9b

4.540 g of white sand and 3.5 g of yellow iron oxide pigment in the form of the powder, already used for producing the yellow granules of Example 7, containing a binder which promotes the dispersing of pigment in concrete, i.e. the Granufin Maize^* of the Davis Colors society, were dry-mixed for 60 seconds in a 5 I container with the help of a Hobarth type mixer. Then 140 g of white cement and 56 ml of water were added to the mixture. The whole was further mixed during 2 minutes.

The mortar obtained was poured into a 3 cm deep square form. The form was conserved for 24 hours at ambient temperature. Then the body of the mortar was extracted from the form.

The mortar bodies according to Examples 9, 9a and 9b were compared for their color: there was no significant difference.

^* Trade-mark Example 10

4.540 g of white sand and 3.5 g of yellow granules of the Example 8 were dried mixed for 60 seconds, in a 5 I container with the help of a Hobarth type mixer. Then 140 g of white cement and 56 ml of water were added. The whole was further mixed for 2 minutes. The mortar obtained was poured into a 3 cm deep square form. The form was conserved for 24 hours at ambient temperature. The mortar body was extracted from the form.

Comparative Example 10a

4.540 g of white sand and 3.5 g of red granules containing a binder which promotes the dispersing of pigment in concrete, the Granufin Terracotta^* of the Davis Colors society, were dry-mixed for 60 seconds in a 5 I container with the help of a Hobarth type mixer. Then 140 g of white cement and 56 ml of water were added to the mixture. The whole was further mixed for 2 minutes. The mortar obtained was poured into a 3 cm deep square form. The form was conserved for 24 hours at ambient temperature. The mortar body was extracted from its form.

Comparative Example 10b

4.540 g of white sand and 3.5 g of red iron oxide pigment in a powder form which was used to produce the granules of Example 10 were dry-mixed for 60 seconds in a 5 I container with the help of a Hobarth type mixer. Then 140 g of white cement and 56 ml of water were added to the mixture. The whole was then mixed for 2 minutes. The mortar obtained was poured into a 3 cm deep square form. The form was conserved for 24 hours at ambient temperature. Then the mortar body was extracted from the form.

The mortar body of Examples 10, 10a and 10b were compared for their color. There was no significant difference.

Trade-mark

Claims

1. A process for producing pigment granules comprising the following steps:

a) preparing a mixture, in the form of a liquid suspension, of an emulsion and/or of a paste, said mixture comprising at least one pigment and at least one binder selected from the group consisting of the organic compounds which form insoluble films after drying and/or by chemical reaction during the drying, said at least one binder being selected such that the films thereby obtained are free of dispersing effects in concretes; and

b) drying of said mixture.

2. Process for producing pigment granules according to claim 1 wherein the mixture further comprises at least one additive for concrete.

3. Process for producing pigment granules according to claim 1 or 2, wherein the mixture obtained in step a) is in the form of an aqueous suspension, of an aqueous emulsion and/or of an aqueous paste.

4. Process according to any one of claims 1 to 3, wherein the binder is selected from the group consisting of the resins and the systems of resins used for preparing varnishes and/or paints.

5. Process according to any one of claims 1 to 4, characterised in that the mixture further contains chemical additives which react with the binder during the drying of said mixture.

6. Process for producing granules according to claim 5, characterised in that the reactive additives react by reticulation with the binder to form insoluble films in water during and/or by the drying process.

7. Process for producing granules according to any one of claims 1 to 6, characterised in that the binder becomes, by drying and/or by chemical reaction accompanying the drying, insoluble and forms a film which stabilizes the mechanical characteristics of the granules without destroying the coloring effect of said pigments.

8. Process for producing pigment granules according to any one of claims 1 to 7, characterised in that the said binder is selected from the group consisting of polymeric acids in an acidic form, polymeric acids in a partially neutralised form and polymeric acids in a neutralized form.

9. Process for producing pigment granules according to claim 8, characterised in that the polymeric acids are selected from the group consisting of the polycarboxylic and polyacrylic acids.

10. Process for producing pigment granules, according to claim 9 characterised in that the polymer acids are selected from the group consisting of the Carbopol^*, Neocryl*, the K-700* Series and Acrysol* G-111.

11. Process for preparing granules according to any one of claims 1 to 7, characterised in that the binder is selected from the group consisting of the copolymers of styrene and of polyacrylic acids, the acrylate vinyls, the copolymers of styrene and of acrylates, the copolymers of the maleic acid anhydride and the latexes used in paint.

12. Process for producing granules according to any one of claims 1 to 11, characterised in that the binder exhibits, before drying, plasticizing and/or tensioactive effects and in that these properties are no more present after drying.

13. Process for producing granules according to any one of claims 1 to 12, characterised in that said mixture contains in weight from 0.1 to 15% of binder with respect to the weight of pigments present in said mixture.

14. Process for producing granules according to any one of claims 5 to 13, characterised in that said chemical additives which react with the binder during the

^* Trade-mark drying of said mixture are selected from the group constituted by polyols, polyethylene glycols and/or oligomers of glycol ethylene, of propanediol, of butanediol, of pentanediol, of pentaerythrite, of trimethylolpropane, of α-Naphtolbenzein, of 2-(2-hydroxyethoxy)phenol, of 1 ,3-dihydroxyacetone dimer, of 1 ,8-dihydroxyantraquinone, of anthrarufin, of 3,5 dihydroxybenzoic acid, of 1 ,5-dihydroxynaphtalene, of 3-hydroxy-2,2-dimethylpropyl 3-hydroxy- 2,2- dimethylpropionate, of acetylenes, of silicone glycol, of sugars and of other polyhydroxy compounds.

15 Process for producing granules according to claim 14, characterised in that the chemical additives reacting with the binder during the drying of said mixture are selected from the group consisting of Surfinol^* 104, Surfinol^* 104 PG50, Surfinol^* 104 DPM, Surfinol* 104 E, Surfinol* 104 BC and Surfinol* 400 Series.

16. Process for producing granules according to any one of claims 5 to 15, characterised in that the reactive additives are used in an amount of 0.1 to 15% with respect to the weight of pigments in the mixture.

17. Process for producing granules according to any one of claims 1 to 16, characterised in that the mixture further comprises at least one volatile catalyst.

18. Process for producing granules according to claim 17, characterised in that the volatile catalyst is a chemical compound which enables to increase the volumetric concentration of pigments in said mixture and which evaporates during the drying step of the mixture.

19. Process for producing granules according to claim 18, characterised in that the volatile catalyst is recovered during the drying step.

20. Process for producing granules according to claim 19, characterised in that the volatile catalyst is recovered by cooling.

^* Trade-mark

21. Process for producing granules according to claim 19 or 20, characterised in that the recovered volatile catalysts are recycled into the process.

22. Process for producing granules according to any one of claims 17 to 21 , characterised in that the volatile catalyst is a dispersant and a tensioactive compound.

23. Process for producing granules according to claim 22, characterised in that the catalyst is an amino alcohol.

24. Process for producing granules according to claim 23, characterised in that the amino alcohol is selected from the group consisting of the AMP, Surfynol^* CT-171 , Surfynol* CT111 , Surfynol* CT 121, Surfynol* CT 131 , acetylenic diols, trietylamine, T-Amine WR500 and acetic acid.

25. Process for producing granules according to claim 24, characterised in that the catalyst is the AMP.

26. Process for producing granules according to any one of claims 17 to 25, characterised in that the catalyst is present in the mixture in an amount of 0.1 to

15% in weight with respect to the weight of pigments in the mixture.

27. Process for producing granules according to any one of claims 1 to 26, characterised in that the pigment is an inorganic pigment.

28. Process for producing granules according to any one of claims 1 to 27, characterised in that the pigment is selected from the group consisting of the manganese oxide, the iron oxides and hydroxides, the chromium oxides, the titanium dioxides, the black carbons and the spinelles.

29. Process for producing granules according to claim 28, characterised in that the pigment is selected from the group of cobalt spinelles.

^* Trade-mark

30. Process for producing granules by drying according to any one of claims 1 to 26, characterised in that the pigment(s) used are organic pigments.

31. Process for producing granules according to any one of claims 1 to 26, characterised in that said at least one pigment used is a mixture of organic pigments and of inorganic pigments.

32. Process for producing granules according to any one of claims 1 to 31 , characterised in that the granules are obtained by a spray granulation of the mixture during the drying step.

33. Process for producing granules, according to any one of claims 1 to 32, characterised in that said mixture further comprises at least one pH regulator.

34. Process for producing granules according to claim 33, characterised in that the pH regulator is selected from the group consisting of sodium acetate, carbonates, NaOH, ammonium salts and sulphuric acid.

35. Process for coloring concrete using as dyes pigments in granular form obtained by the process according to any one of claims 1 to 34.

36. Pigment granule comprising:

less than 20% of water;

from 79 to 99.95% of pigments; and

from 0.05 to 15% of binders selected from the group consisting of the organic compounds which form insoluble films after drying and/or by chemical reaction accompanying the drying, said binders being selected so that the films thereby obtained are free of dispersing effects in concretes,

37. Pigment granule according to claim 36, characterised in that it contains less than 4% of water and from 79 to 99.95% of pigments.

38. Pigment granule comprising:

less than 10% of water;

- from 39.5 to 49.945% of pigments;

from 0.025 to 7.5% of binders selected from the group consisting of the organic compounds which form insoluble films after drying and/or by chemical reaction accompanying the drying, said binders being selected such that the films thereby obtained are free of dispersing effects in concretes; and

up to 50% of additives for concretes,

39. Pigment granule according to any one of claims 36 to 38, characterised in that the binder is selected among the resins and the systems of resins usable for producing varnish and/or paints.

40. Pigment granule according to claim 39, characterised in that it contains from 0.5 to 8% of binder.

41. Pigment granule according to claim 40, characterised in that it contains from 0.8 to 5% of binder.

42. Granule according to claim 41 , with a size ranging from 30 micrometers to 3 mm.

43. Granule according to claim 42, with a size ranging from 35 micrometers to 2 mm.

44. Granule according to claim 43, with a size ranging from 40 to 500 micrometers.

45. Granule according to claim 44, with a size ranging from 40 to 400 micrometers.

46. Granule according to any one of claims 36 to 45, characterised in that it is in the form of a pearl.

47. Mixture of pigment granules according to anyone of claims 36 to 46 containing at least 90% of pearls having a size ranging from 40 to 400 microns.

AMENDED CLAIMS

[received by the International Bureau on 06 February 2001 (06.02.01); original claims 1-47 replaced by new claims 1-46; (4 pages)]

1. A process for producing pigment granules for coloring concrete comprising the following steps:

b) subjecting of said mixture to spray granulation and drying.

5. Process according to any one of claims 1 to 4, characteπsed in that the mixture further contains chemical additives which react with the binder during the drying of said mixture.

7. Process for producing granules according to any one of claims 1 to 6, characterised in that the binder becomes, by drying and/or by chemical reaction accompanying the drying, insoluble and forms a film which stabilizes the

32. Process for producing granules, according to any one of claims 1 to 31 , characterised in that said mixture further comprises at least one pH regulator.

33. Process for producing granules according to claim 32, characterised in that the pH regulator is selected from the group consisting of sodium acetate, carbonates, NaOH, ammonium salts and sulphuric acid.

34. Process for coloring concrete using as dyes pigments in granular form obtained by the process according to any one of claims 1 to 33.

35. Pigment granule comprising:

less than 20% of water;

- from 79 to 99.95% of pigments; and

36. Pigment granule according to claim 35, characterised in that it contains less than 4% of water and from 79 to 99.95% of pigments.

37. Pigment granule comprising:

less than 10% of water;

from 39.5 to 49.945% of pigments;

up to 50% of additives for concretes,

38. Pigment granule according to any one of claims 35 to 37, characterised in that the binder is selected among the resins and the systems of resins usable for producing varnish and/or paints.

39. Pigment granule according to claim 38, characterised in that it contains from 0.5 to 8% of binder.

40. Pigment granule according to claim 39, characterised in that it contains from 0.8 to 5% of binder.

41. Granule according to claim 40, with a size ranging from 30 micrometers to 3 mm.

42. Granule according to claim 41, with a size ranging from 35 micrometers to 2 mm.

43. Granule according to claim 42, with a size ranging from 40 to 500 micrometers.

44. Granule according to claim 43, with a size ranging from 40 to 400 micrometers.

45. Granule according to any one of claims 35 to 44, characterised in that it is in the form of a pearl.

46. Mixture of pigment granules according to anyone of claims 35 to 45 containing at least 90% of pearls having a size ranging from 40 to 400 microns.

STATEMENT UNDER ARTICLE 19(1 )

In order to better define the process according to the invention, original claim 1 has been amended to specify that: the granules prepared by the claimed process are intended to be used « for coloring concrete »; and step (b) of the claimed process includes a "spray granulation".

In view of the amendment made to original 1 , original claim 32 has been deleted as being redundant and the numbering and dependency of the remaining claims have been amended accordingly.

It is worth noting that the statement of the invention on pages 8 and 9 of the original description should be amended to conform with the invention as now reflected in newly submitted claim 1 .

The detailed description of step (b) of the claimed process from page 1 6, line 20, 1 8 to page 1 7, line 1 6 of the original description, should also be amended accordingly.