Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B7/00—Moulds; Cores; Mandrels
  • B28B7/38—Treating surfaces of moulds, cores, or mandrels to prevent sticking
  • B28B7/384—Treating agents

Definitions

• the invention relates to a composition for demolding, particularly useful for the manufacture of moldings of hydraulic setting material such as concrete.
• mold release oils still have certain disadvantages.
• it remains difficult to obtain parts having a homogeneous surface appearance.
• the present invention therefore aims to provide a demolding composition of molded parts of hydraulic setting material to obtain a molded part having a homogeneous surface appearance. It also aims to provide a mold release composition does not have one or more of the disadvantages mentioned. Finally, it aims to propose a release composition conferring a water-repellent or colored character to the molded part.
• the demolding composition preferably also fulfills the following requirements: a viscosity allowing, for example, the application by spraying;
• the invention is based on the surprising finding that the introduction of a calcium salt in a mold release oil improves the surface appearance of the molded parts while maintaining the demolding qualities.
• the invention provides a mold release composition, intended for the manufacture of parts made of hydraulically setting material, comprising at least one oil and at least one calcium salt, calcium borates and sodium salts. calcium of fatty acids being excluded from the calcium salts according to the invention.
• the oil is an oil of plant or animal origin.
• Particularly preferred is a composition wherein the oil comprises one or more compounds selected from fatty acid esters, and especially fatty acid triglycerides, and neopentyl polyol fatty acid esters.
• the calcium salt is preferably selected from chloride, bromide, nitrite and calcium thiocyanate.
• the composition comprises 0.1 to 70% by weight of calcium salt.
• the composition may especially be formulated in the form of a solution, an emulsion or a suspension.
• the demolding composition may further comprise one or more compounds chosen from a stabilizer, a dispersant, a surfactant, a preservative, a solvent, a thickener and a thixotropic agent, in particular one or more compounds chosen from a water-repellent agent and a pigment. .
• It may comprise, as water-repellent agent, especially products based on silicones, silanes, siloxanes or metal salts of fatty acids. It may comprise, as pigment, in particular one or more inorganic oxides or hydroxides and more particularly one or more pigments chosen from titanium dioxide, iron, cobalt or chromium oxides.
• the invention is directed to a method of preparing molded parts of hydraulically setting material, comprising the step of:
• the coating of the mold is carried out by spraying.
• the invention relates to a molded part that can be obtained by the above method, in particular in which the hydraulic setting composition is a cementitious composition, especially a concrete.
• the demolding composition according to the invention comprises at least one calcium salt.
• calcium salt is intended to cover compounds comprising at least one calcium ion and at least one inorganic or organic counterion.
• Particularly targeted are calcium halides such as chloride, bromide; calcium thiocyanate, calcium hydroxide, salts of nitrogenous ions such as nitrate, nitrite or calcium nitride, salts of sulfur-containing ions such as sulphate, sulphite, calcium bisulphite, or salts of carboxylic or hydroxycarboxylic acids such as lactates.
• chloride, bromide, nitrite and calcium thiocyanate are preferred, and in particular calcium nitrite.
• Calcium borates and calcium salts of fatty acids are excluded from this definition.
• the concentration of calcium salt can vary widely depending on the formulation without significantly affecting the result.
• a low concentration of calcium salts in the order of 0.1% by weight based on the weight of the demolding composition, is sufficient to improve the surface appearance of the molded parts.
• the upper limit of the calcium salt concentration is dictated, depending on the chosen formulation, mainly by their solubility and / or economy considerations, since there is generally no further improvement beyond a concentration of about 70% by weight of calcium salt relative to the final mold release composition.
• the composition will generally contain from 0.1 to 70% by weight of anhydrous calcium salt.
• the demolding composition according to the invention also comprises at least one oil. In order to optimize its properties, the composition generally comprises a mixture of different oils.
• oils are understood to mean a substantially hydrocarbon material which is liquid at ambient temperature and immiscible with water.
• the oils reduce the coefficient of friction and thus facilitate demolding.
• mineral, animal and vegetable oils are particularly distinguished.
• all the oils can in principle be used.
• animal or vegetable oils are preferred. Indeed, they are more polar and it is found that the molded parts have a more homogeneous surface appearance, including a decrease in the appearance of bubbles.
• mineral oils are subject to strict regulation at the level of their discharge.
• Vegetable oils are particularly preferred. Indeed, these contain functions that are likely to be saponified in an alkaline medium to give an alcohol and calcium acid salt, and thus allow good transfer of additives to the surface of the hydraulic setting part.
• esters such as fatty acid triglycerides, fatty acid esters or complex esters such as neopentyl polyol fatty acid esters.
• the composition may be formulated in monophasic, two-phase or multiphasic form. It may especially be in the form of a solution, a simple or complex emulsion, a gel or a suspension.
• composition may also comprise one or more formulation adjuvants, such as in particular stabilizers, dispersants, surfactants, preservatives, solvents, thickeners and thixotropic agent.
• formulation adjuvants such as in particular stabilizers, dispersants, surfactants, preservatives, solvents, thickeners and thixotropic agent.
• the demolding composition further comprises water-repellent agents and / or pigments in order to improve the properties and the surface appearance of the molded parts.
• water-repellent agents examples include products, solid or liquid, based on silicones (eg Masterseal 530 from Degussa, Aerosil
• inorganic pigments such as, in particular, oxides or hydroxides of metals such as iron, chromium, titanium, cobalt, aluminum or manganese, their mixtures and compounds mixed, as well as carbon black. Titanium dioxide and / or iron, cobalt or chromium oxides are preferably used.
• inorganic pigments and their mixtures are known per se and sold in particular by the company Chryso, France. It is found that the calcium salts also make it possible to compatibilize the mineral pigments with the surface.
• Titanium dioxide by virtue of its photocatalytic properties, can also be used as a depollution agent.
• the hydraulically setting material can be tinted also with organic pigments such as catechol or bromothymol blue.
• inorganic pigments will preferably be chosen.
• pigments may be added in varying amounts, but generally in the range of 2 to 70%, preferably 5 to 40% by weight, based on the final composition.
• the demolding composition is in principle easy to manufacture.
• the calcium salt is generally poorly soluble in oil, it is preferably introduced in the form of a solution, in particular an aqueous solution.
• the two phases can be mixed in a manner known per se, for example in a suitable mixer, and a more or less stable emulsion is obtained.
• the oily phase constitutes the continuous phase (W / O emulsion) or the dispersed phase (O / W emulsion).
• different formulations can be produced, such as gels.
• Formulations in emulsion form are preferably unstable under shear. Indeed, it is found that the rapid separation of the phases during application causes a drop in viscosity, which facilitates homogeneous application.
• the invention is directed to a method of preparing molded parts of hydraulically setting material, comprising the step of:
• the coating of the mold with the demolding composition may be carried out by means known per se, for example by application with a brush, a cloth, or a roll, by dipping or else by spraying, this latter mode of application being preferred.
• the amount of the composition to be applied is chosen to be sufficient to form a continuous film over the entire surface of the mold to be in contact with the hydraulic setting composition.
• the thickness of the oil film formed is generally of the order of 1 to 15 micrometers.
• the amount of composition depends on its viscosity and thus its formulation.
• the material and topology of the mold may also be factors to consider.
• a composition having a viscosity of about 50 mPa.s on a metal mold.
• the amount applied will be greater on absorbent molds, for example of wood, or for a higher viscosity formulation.
• the demolding composition is effective on molds of different materials. We can thus particularly include metal molds, wood, bakelized wood or polymer.
• composition with hydraulic setting refers to mineral compositions whose setting is conditioned by the addition of water, such as compositions based on cement and preferably Portland cement, such as mortars or concretes.
• composition described thus allows access to molded parts of aesthetic appearance compatible with a demanding application, for example for uncovered facings after stripping.
• the invention aims in another aspect the molded hydraulic setting compositions, including a cement composition such as concrete, obtainable by the implementation of the composition described.
• a suitable container 50 parts by weight of vegetable mold release oil (CHRYSO®Dem ECO2) are introduced and then 14.20 parts by weight are introduced.
• the phases are mixed with an Ultra-Turrax mixer and a stable mixture is obtained for several hours.
• a suitable container 50 parts by weight of vegetable release oil (CHRYSO®Dem ECO2) are introduced and then 16 parts by weight of calcium chloride, 12 parts by weight of TiO 2 (Degussa's Aeroxide P25) and finally 22 parts by weight of an emulsion of anti-efflorescence agent, water-repellent (Rheomix 791 from Degussa).
• CHRYSO®Dem ECO2 vegetable release oil
• the demolding behavior of the compositions prepared according to Examples 1 to 6 was evaluated for mortar compositions in the following manner. An appropriate amount of mold release composition was applied to metal molds using a cloth. After drying, a mortar composition prepared from the components detailed in Table 1 was introduced into the mold. The part was then demolded after curing the composition. Table 1: Composition of the test mortar
• Table 5 Composition of test concrete of fluid concrete type
• the release compositions according to the invention make it possible to obtain moldings made of hydraulically setting material having an improved surface appearance, in particular with regard to the number of surface defects. In addition, they preserve the quality of the mold by minimizing clashes.
• demolding compositions according to the invention make it possible to provide molded surfaces with stable and homogeneous coloration and / or water-repellency.
• the photocatalytic effect obtained on the surface of the demolded parts was evaluated for mortar compositions in the following manner.
• red dye from Sigma Aldrich
• the pieces are subjected to UV irradiation, while a spectrocolorimetric monitoring, according to the L * .a * .b *. System, of the parameter a * (red index) as a function of time is carried out on polluted areas.
• the results are collated in FIG. 1, which represents the evolution of the percentage of degradation of the red color as a function of time for two types of TiO 2.
• the solid circles correspond to the demolding oil comprising Degussa P90, and the mold release oil triangles comprising Crystal P105.
• the use of photocatalytic mold release oils makes it possible to obtain a color degradation of greater than 40% after 3 hours of UV irradiation. For a control without TiO2 in the demolding oil, the degradation is non-existent.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Mechanical Engineering (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)

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• 2006
  • 2006-12-18 FR FR0611035A patent/FR2909918B1/fr not_active Expired - Fee Related
• 2007
  • 2007-12-14 EP EP07871862A patent/EP2091887A1/de not_active Withdrawn
  • 2007-12-14 CA CA2672842A patent/CA2672842C/fr not_active Expired - Fee Related
  • 2007-12-14 US US12/519,804 patent/US8080103B2/en not_active Expired - Fee Related
  • 2007-12-14 WO PCT/FR2007/002071 patent/WO2008087298A1/fr not_active Ceased

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