The present invention relates to the use for the manufacture of cement with a composition comprising at least one sacrificial molecule to protect dispersants during clinker grinding.

Dispersants are generally organic molecules, such as polymers. One of their uses may be the thinning of hydraulic compositions or other mineral fillers. In practice, they are most often added to hydraulic compositions or other mineral fillers during the mixing phase or in the mixing water or along the different components.

It may be advantageous to add the dispersant directly to the cement during its production. However, when the clinker is ground with calcium sulfate, which can for example be added in the form of gypsum or anhydrite for cement.

However, it was found that dispersants suffer a reduction or total loss of their plasticizing power when subjected to grinding. This effect of grinding on the effectiveness of dispersants does not add dispersants in cement when it is being milled.

To meet user requirements and ensure the effectiveness of dispersants, it became necessary to find a new way to protect dispersants subjected to grinding for cement production, and thus maintain their plasticizing properties.

Thus the problem to be solved by the invention is to provide a new means adapted to protect against dispersants partial or total reduction in their plasticizing power for grinding during cement production, ie to maintain or part all their fluidifying properties during grinding.

Unexpectedly, the inventors have demonstrated that it is possible to use a sacrificial molecule, such as an antioxidant, protecting the dispersants during grinding.

For this purpose the present invention provides the use for the manufacture of cement with a composition comprising at least one dispersant and at least one sacrificial molecule to maintain part or all of the dispersant properties, the composition

being in the form of either a liquid solution or an emulsion or is suspended;

the amount of the sacrificial molecule in the composition representing at least 5% by weight of the dispersant of mass; and

being introduced before or during the grinding of the clinker.

The invention has the advantage of being implemented in all industries using a grinding process, including building industry, chemical industry (admixture producers), the cement industry, or the grinding stations.

Other advantages and features of the invention will become apparent from reading the description and examples given purely illustrative and not limiting that follow.

by expression means "sacrificial molecule" according to the present invention a molecule capable of operating in one of two ways in order to maintain part or all of the fluidifying properties of a dispersant when it is subjected to grinding: either deteriorate instead of the dispersant or react with the dispersant in order to protect it. Preferably, the sacrificial molecule is degraded in place of the dispersant. A preferred sacrificial molecule is an antioxidant.

Is meant by the term "antioxidant" according to the present invention a molecule adapted to capture electrons or free radicals and then stabilized.

Is meant by the term "dispersant" according to the present invention an organic molecule used in the field of hydraulic or other mineral fillers compositions to fluidize said hydraulic compositions or said other inorganic fillers. A dispersant according to the present invention may especially be a plasticizer / water reducer or superplasticizer / high range water reducer as defined in EN 934-2 in paragraphs 3.2.2 and 3.2.3. The fluidity of a hydraulic composition can be evaluated by measuring the spread according to the protocol described below.

Is meant by the term "polycarboxylate polyethylene oxide / propylene" or "PCP" according to the present invention a copolymer of acrylic acid and / or methacrylic, their oxide esters of ethylene / propylene (POE / POP) or their ethers, POE / POP. The term "polyethylene oxide / propylene" means in this specification polyethylene oxide, or ethylene oxide and propylene.

Is meant by the term "grinding" in the present invention, the step of dividing a solid to reduce the particle size and / or to increase their specific surface (developed surface of the powder per unit mass).

by expression means "hydraulic composition" according to the present invention a composition comprising a hydraulic binder. Preferably, the hydraulic composition is a mortar or a concrete.

by expression means "hydraulic binder", according to the present invention a compound having the property of hydrating in the presence of water and the hydration of which allows to obtain a solid having mechanical characteristics. Preferably, the hydraulic binder is a cement.

the term means "glue" of the present invention cement as defined in EN 197.1 and aluminous cements. Preferably, the cement is Portland cement.

the term means "clinker" according to the present invention the product obtained after curing (clinkering) of a mixture (raw) consisting, inter alia, limestone and for example clay. Preferably, the clinker is a Portland clinker as defined in EN 197.1 standard.

by expression means "mineral fillers" according to the present invention any mineral product in powder form, whose use may require the presence of a dispersant and / or may be used in a hydraulic composition.

the term means "emulsion" according to the present invention a homogeneous mixture of two immiscible liquids, a substance being dispersed in the second substance in the form of small droplets having a size of about one micrometer.

Is meant by the term "suspension" of the present invention a colloidal dispersion in which a finely divided, in liquid or solid form, is combined with another product in liquid form, the first product being in the form of droplets or particles larger than one micrometer, but small enough that said first product is redeposited rapidly.

An object of the present invention is the use for the manufacture of cement with a composition comprising at least one dispersant and at least one sacrificial molecule to maintain part or all of the dispersant properties, the composition

being in the form of either a liquid solution or an emulsion or is suspended;

the amount of the sacrificial molecule in the composition representing at least 5% by weight of the dispersant of mass; and

being introduced before or during the grinding of the clinker.

Preferably, an object of the invention is the use of at least one sacrificial molecule said sacrificial molecule is adapted to degrade in place of dispersant is reacted with the dispersant in order to protect it.

Preferably, the dispersant and the sacrificial molecule are in the form of a liquid solution.

Preferably, the dispersant and the sacrificial molecule are not in the form of a solid solution.

Preferably, the dispersant and the sacrificial molecule are not added separately. In other words, they are added sequentially. They are preferably added simultaneously.

A variant of the object of the present invention is the use for the manufacture of cement with a composition comprising at least one dispersant and at least one sacrificial molecule to maintain part or all of the dispersant properties, the composition

being in the form of either a liquid solution or an emulsion or is suspended;

not being in powder form;

the amount of the sacrificial molecule in the composition representing at least 5% by weight of the dispersant of mass;

being introduced before or during the grinding of the clinker.

For example, in the case where the dispersant is subjected to grinding to 100 0 C for 1 h30, the sacrificial molecule may be present in an amount greater than or equal to 5%, preferably 10%, more preferably 15%, even more preferably 20% by dry weight relative to the dry mass of the dispersant.

Preferably, the sacrificial molecule is soluble in a solution of the dispersant.

Preferably, the sacrificial molecule is selected from antioxidants. An antioxidant can be a hydrogen donor, a decomposer of hydroperoxides, alkyl radical scavenger, or a reducing agent in a redox reaction. Preferably, the antioxidant comprises a reactive group such as an OH group or an NH group, preferably associated with a phenolic or aromatic ring.

The antioxidant may be chosen from the following compounds, alone or in admixture:

- hydroquinone, methoxyphenol, methoxyhydroquinone;

- 5-ethyl-1-aza-3,7-dioxabicyclo (3.3.0) octane;

- 1-aza-3,7-dioxabicyclo (3.3.0) octane-5-methanol;

- ascorbic acid, sodium ascorbate, calcium ascorbate, 5-6-1-ascorbic acid diacetyl, palmityl 6-1-ascorbic acid;

pormule 1: Ascorbic acid

- citric acid, sodium citrate, potassium citrate and calcium citrate;

COOH

I

HOOC- CH Z - C-CH 2 - COOH

I

OH

Formula 2: citric acid

- tartaric acid, sodium tartrate, potassium tartrate and sodium and potassium tartrates;

OH OH

A x ^ -COGH Cook

HOOC HOOC" Υ"

OH OH

M+)

OH

.X ..COOH

HOOC V

OH

meso Formula 3

- butylhydroxytoluol et butylhydroxyanisol;

4: ortho and meta butylhydroxytoluol

Formule 5 : butylhydroxyanisol

- gallic acid and its esters, such as methyl gallate, propyl gallate, octyl gallate or dodecyl gallate;

- lactates de sodium, lactates de potassium ou lactates de calcium ;

- lecithin;

- Natural tocopherols, alpha-tocopherol synthesis, gamma-tocopherol and delta-tocopherol synthesis synthesis;

- organic phosphorus compounds such as phosphites or phosphonites, such as the following compounds:

TNPP

Form 6 which means TNPP tris (nonylphenyl) phosphite.

- organosulfur compounds, such as esters of thiodipropionic acid or 3,3-esters of sulfurous acid, with the exception of salts of sulfurous acid;

- hydroxylamines ;

- lactones, acrylic bisphenols, substituted benzofuranones;

- derivatives sebacate 2,2,6,6-tetramethyl piperidine:

R - H, CH 3 ou OC 8 H 17 Formula 7

Preferably, the sacrificial molecule is selected from phenols, polyphenols, phenolic acids and their related esters, aromatic secondary amines, organophosphorus compounds, organosulfur compounds except for salts of sulfurous acid, organic acids and their associated esters, hydroxylamines, reducing oxidation-reduction reactions, their associated salts and mixtures thereof.

In particular, the sacrificial molecule is preferably selected from phenols, polyphenols, phenolic acids and their related esters, aromatic secondary amines, hydroxylamines, their associated salts and mixtures thereof.

Preferably, the sacrificial molecule is selected from hydroquinone, methyl gallate, propyl gallate, gallic acid and hydroxylamine.

Preferably, the sacrificial molecule is 4-methoxyphenol or appointed MEHQ.

Alternatively, the invention further object the use for the manufacture of cement with a composition comprising at least one dispersant and at least 4-methoxyphenol to maintain part or all of the dispersant properties, the composition

being in the form of either a liquid solution or an emulsion or whether a suspension, and

the amount of the sacrificial molecule in the composition representing at least 5% by weight of the dispersant of mass;

being introduced before or during the grinding of the clinker.

Preferably, the dispersant is selected from polycarboxylates of polyethylene oxide / propylene, polynaphthalene sulfonates, lignosulfonates, polymelamine sulfonates and mixtures thereof. In particular, the dispersant is preferably a polyethylene oxide polycarboxylate.

According to a variant of the invention, the dispersant may be used in liquid form, the sacrificial molecule can be used in the form of powder or liquid and the sacrificial molecule may be soluble in a solution of the dispersant. The solubility of the sacrificial molecule in a solution of the dispersant allows a homogeneous mixture of these two compounds, which are then in the form of a liquid solution.

According to another variant of the invention, the sacrificial molecule may not be soluble in a solution of the dispersant, and the dispersant and the sacrificial molecule can be used in the form of an emulsion or a suspension. In order to obtain an emulsion / stable suspension, it is possible to use additionally a stabilizer.

According to another variant of the invention, it is possible to copolymerize the sacrificial molecule and the dispersant, so as to integrate the sacrificial molecule directly in the backbone of the dispersant. In this sacrificial molecule and the dispersant may be copolymerized. Especially when the dispersant is a polymer, it may be possible to graft the sacrificial molecule of this polymer. This grafting may be done during synthesis of the polymer, for example by radical route. Monomeric antioxidants may be then integrated by radical copolymerization in a PCP-like structure. For example, the monomers may be selected from the molecules described in Table 1 below.

Table 1: monomers antioxidants

The dispersant may include one or more types of dispersants. Similarly, the sacrificial molecule may comprise one or more types of sacrificial molecules.

Other conventional adjuvants may also be used with the dispersant and the sacrificial molecule, such as a setting accelerator, a setting retarder or an antifoaming agent.

Preferably, the amount of sacrificial molecule is at least 5%, preferably at least 10%, even more preferably at least 15% by dry weight relative to the dry mass of the dispersant.

Preferably, the amount of sacrificial molecule is less than or equal to 40%, preferably less than or equal to 20%, by dry weight relative to the dry mass of the dispersant.

Preferably, the concentration of the mixture comprising the sacrificial molecule and the dispersant in a cement is in the range of 0.05 to 5% by mass relative to the cement mass.

It should be noted that the dosage sacrificial molecule with respect to the dispersant to be protected may be dependent on the nature of the sacrificial molecule and the nature of the dispersant.

According to a particular embodiment of the invention, the composition comprising at least one sacrificial molecule and at least one dispersant can be used during the manufacture of cement comprising mineral additives to maintain some or all the properties of the dispersant. According to this variant, the mineral additives are added during manufacture of the cement before or during the grinding of the clinker.

The term "mineral addition" means the invention dairy

(As defined in the "Cement" NF EN 197-1 paragraph 5.2.2), the steel slags, pozzolanic materials (as defined in the standard "Ciment" NF EN 197-1 paragraph 5.2.3) , fly ash (as defined in the standard "Ciment" NF EN 197-1 paragraph 5.2.4), calcined schists (as defined in the standard "Ciment" NF EN 197-1 paragraph 5.2.5), the limestone (as defined in the standard "Ciment" NF EN 197-1 paragraph 5.2.6) or fume silica (as defined in the standard "Ciment" NF EN 197-1 paragraph 5.2.7) or their mixtures.

Preferably, the amount of mineral clinker with addition range is 10 to 70% of mineral additions, more preferably from 10 to 60%, even more preferably from 10 to 50%,% by weight based on the total weight clinker.

Another object of the invention is the use of a cement with the composition as described above for the manufacture of a hydraulic composition. Another object of the invention is the use of an inorganic filler as described above for the manufacture of a hydraulic composition. As part of these two uses of the invention, the sacrificial molecule and the dispersant have the same characteristics as those described in connection with the first use according to the invention.

Measuring the spread and monitoring rheology

The spread mortar was measured using a mini Abrams cone whose volume is 800 mL. The dimensions of the cone are the following:

- diameter of the circle of the upper base 50 +/- 0.5 mm;

- diameter of the circle of the lower base 100 +/- 0.5 mm;

- height 150 +/- 0.5 mm.

The cone is placed on a dried glass plate and filled with fresh mortar. He then leveled. Lifting the cone causes a mortar sagging on the glass plate. The diameter of the wafer obtained was measured in millimeters +/- 5 mm. Is the spreading of the mortar.

These operations, repeated several maturities (5, 15 and 30 minutes), allow to follow the evolution of the rheology of the mortar for 30 minutes.

The following examples illustrate the invention without limiting its scope.

EXAMPLES

Example 1: Validation of the effect of sacrificial molecules on reducing the plasticizing power of various dispersants for the production of cements in their grinding

Different mortars were produced and their rheology was measured. These mortars were made with either a cement comprising composition according to the invention (that is to say, the composition is added during the grinding of the clinker), or they were carried out with a traditional cement, the dispersant and optionally the sacrificial molecule have been added into the mortar (control).

Dispersants that have been tested are CFP and particularly a PCP from a laboratory synthesis with 30% rate of ester MMPEG 1100 (methacrylate of methoxypolyethylene glycol having a molar mass of 1100 g / mol), a PCP from a laboratory synthesis having 20% ​​of ester rates MMPEG 1100, the Premia 180 (Supplier: Chryso), the Premia 196 (Supplier: Chryso), Optima 200 (Supplier: Chryso) and Optima 203 (Supplier: Chryso).

PCP from a laboratory synthesis tested in the various examples of the present disclosure were synthesized by radical polymerization in water between methacrylic acid and the methacrylate of methoxypolyethylene glycol having a molar mass of 1100 g / mol . Depending on the rate of desired ester, modifying the initial amounts of the two monomers were changed.

The reagents used for this test and their amounts are:

• methacrylic acid (AM) (Supplier: Aldrich): 63.0 g

• methacrylate, methoxy polyethylene glycol (MMPEG1 100) (Supplier: Aldrich): 341, 7 g

• azo initiator (AIBN azobis (isobutyronitrile) - Supplier: Dupont - Vazo

64) : 3,435 g

• transfer agent: thioglycolic acid (TGA - Supplier: Aldrich): 5.780 g

• solvent: water: 553.6 g

The procedure for the manufacture of PCP tested is as follows:

• introducing the monomers (AM and MMPEG1 100) in the balloon;

• place the refrigerant above the tank;

• Start the heating to a temperature of 70 0 C;

• realize degassing with nitrogen for 30 minutes;

• when the initial temperature is reached, add the transfer agent (ATG) and the initiator (AIBN);

• scan to nitrogen;

• allow the reaction to proceed at 70 0 C for 2 hours;

• stop heating and cool;

• neutralization start when the temperature falls below 30 0 C (32.51 g of Ca (OH) 2 );

• filter through a filter having pores with a maximum diameter of 80 microns.

The sacrificial molecules tested in the present example are methyl gallate, propyl gallate, hydroquinone, hydroxylamine and gallic acid (Supplier: Aldrich), 4-methoxyphenol (ECEM Provider).

The cement was ground according to the protocol described below. The mill which has been used is a mill which may contain 5 kg of material to be ground and having 60 kg of metal balls, in an amount of 27 kg of balls having an average diameter of between 40 and 60 mm, 18 kg of balls whose average diameter of between 25 and 35 mm and 15 kg of balls whose mean diameter is between 20 and 25 mm. The grinder was used at a speed of 40 rpm. The steps of grinding are as follows:

- introduction of 4727.1 g of Portland clinker in the form of balls of maximum diameter less than or equal to 3.15 mm in a mill, either at room temperature for grinding at 20 ° C is preheated to 115 ° C for a grinding to 100 0 C;

- spraying the dispersant alone or of the composition according to the invention (+ dispersant sacrificial molecule) on the clinker;

- grinding for 500 revolutions, and then opening of the crusher and monitoring of the clinker temperature;

- grinding for 500 revolutions, and then temperature control and control of the Blaine specific surface of the clinker according to EN 196-6;

- grinding for 800 revolutions, and then temperature control and control of the Blaine specific surface of the clinker according to EN 196-6;

- introduction of gypsum and hemihydrate in weight proportion 60% / 40% is 174.77 g and 98.09 g of gypsum hemihydrate;

- grinding for 800 revolutions, and then temperature control and control of the Blaine specific surface of the clinker according to EN 196-6;

- grinding for 250 revolutions, and then temperature control and control of the Blaine specific surface of the clinker according to EN 196-6;

- implementation of the drain grate to retrieve the last few laps grinding cement having the desired size;

- grinding for 400 revolutions;

- homogenizing the ground cement in a Turbula 15 L for 20 minutes at

24 rpm;

- final control of the Blaine specific surface of the clinker according to EN 196-6.

After milling, the cement was used for the manufacture of a mortar, to which monitoring the rheology was performed to highlight the effect of the sacrificial molecule.

The formulation of the test mortar was as follows:

Water / Cement 0.62

Total ciment 404,4 g

Sable ISO 1350,0 g

Total eau 252,5 g

Water prewetting 81 g 0

Mixing water 171, 5 g

Cement is a cement CEM I 52.5 N.

The ISO sand is a silica sand (Supplier: Société Nouvelle du Littoral).

The tested mortar was made according to the protocol described below:

1) introduction of ISO sand in the bowl of a Perrier mixer;

2) from 0 to 30 seconds: the beginning of low speed mixing (140 rpm) and introduction of water prewetting in 30 seconds;
3) 30 seconds to 1 minute, mixing sand and water prewetting for 30 seconds;
4) from 1 minute to 5 minutes, stand for 4 minutes;
5) 5 minutes 6 minutes, introduction of the cement;
6) 6 minutes, 7 minutes, kneading for 1 minute at slow speed;

CLAIMS

1- Use in the manufacture of cement with a composition comprising at least one dispersant and at least one sacrificial molecule to maintain part or all of the dispersant properties, the composition

being in the form of either a liquid solution or an emulsion or is suspended;

the amount of the sacrificial molecule in the composition representing at least 5% by weight of the dispersant of mass; and

being introduced before or during the grinding of the clinker.

2- Use according to claim 1 wherein the composition is a liquid solution.

3- Use according to any one of claims 1 to 2, wherein the sacrificial molecule is selected from antioxidants.

4- The use of claim 3, wherein the sacrificial molecule is selected from phenols, polyphenols, phenolic acids and their related esters, aromatic secondary amines, hydroxylamines, their associated salts and mixtures thereof.

5- Use according to claim 4, wherein the sacrificial molecule is 4- methoxyphenol.

6- Use according to any one of claims 1 to 5, wherein the amount of the sacrificial molecule in the composition representing at least 2% by weight of the dispersant compound. To check

7- Use according to any one of claims 1 to 6, wherein the amount of sacrificial molecule in the composition is less than or equal to 50% by mass relative to the mass of the dispersant.

8. Use according to any one of claims 1 to 7, wherein the sacrificial molecule and the dispersant were copolymerized.

- Use for the manufacture of cement with a composition comprising at least 4-methoxyphenol and at least one dispersant to maintain part or all of the dispersant properties, the composition

being in the form of either a liquid solution or an emulsion or whether a suspension, and

the amount of the sacrificial molecule in the composition representing at least

1% by weight of the dispersant of mass;

being introduced before or during the grinding of the clinker.