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 subject of the invention is a concentrate for demolding emulsion of hydraulic binders.
• the invention also relates to an emulsion of the oil in water type, prepared by diluting said concentrate in water and its use for the release of hydraulic binders.
• release agent has the function of facilitating the removal of the molded element after the setting of the hydraulic binder.
• release agents have been proposed in the state of the art.
• German patent application No. 2 925 485 relates to a mold release dispersion for concrete molds comprising 6 to 30 parts of mineral wax, 1 to 7 parts of an emulsifier such as an ethoxylated alkyl phenol or a fatty acid , and water.
• This dispersion must be applied at high temperature and has the further disadvantage of not being able to form a continuous coating on the surface of the molds, which results in a poor surface condition of the molded body and fouling of the molds.
• French Patent No. 2,487,848 relates to emulsions of the water in oil type, the oily phase of which is the combination of one or more hydrocarbon and / or chlorinated solvents, of an oil, of at least one fatty substance and of a surfactant.
• These water-in-oil type emulsions have a high viscosity, which makes their spraying difficult and results in high emulsion / surface area ratios to be coated and high costs.
• the film covering the mold is only rarely continuous and since it generally does not adhere sufficiently to the mold, it is entrained during the pouring of the concrete.
• the surface condition of the demolded element is then hardly satisfactory and the molds clogging quickly, they must be cleaned frequently.
• the user can not store the formwork product in a ready-to-use form, as this would require a large storage volume due to the great dilution of the product.
• European patent n ° 180 630 describes oil-in-water emulsions containing, based on the weight of the total emulsion, 10 to 90% water, 10 to 90% of an oily constituent, 0.5 to 20% of nonionic surfactants in combination with anionic surfactants present in the form of salts and the amount of which relative to the nonionic surfactants is from 1 to 100% by weight. But these emulsions whose interest is not questioned, are relatively expensive, which tends to limit their use in trades already undergoing the vagaries of economic conditions.
• the invention also relates to the emulsions of the oil in water type that the concentrates make it possible to obtain by dilution in water.
• an oily constituent it is possible to use a mineral oil or a mixture of several mineral oils; a triglyceride having 10-24 carbon atoms in each fatty acid portion, optionally mixed with a mineral oil; one or more esters of an aliphatic carboxylic acid with a mono- or dihydric alcohol; a mixture of one or more mineral oils and esters as mentioned above, optionally also comprising a triglyceride having 10-24 carbon atoms in each fatty acid portion.
• Emulsions prepared with a mixture of esters as defined above and mineral oil will generally be more stable when the oily component consists of a mixture comprising 90% by weight of mineral oil and 10% by weight of ester as defined above.
• the oily component of the concentrate can also consist of mixtures of triglycerides having 10-24 carbon atoms in each fatty acid and / or mineral oil portion and / or one or more esters as defined above and below. Chlorinated oils, polyglycols, C10 ⁇ 20 fatty alcohols and other oily constituents can be used as additional oily constituents.
• Examples of triglycerides having 10-24 carbon atoms in each fatty acid portion are vegetable oils and marine oils.
• the oily component is a mineral oil, it is preferable that this oil contains at most 9% of aromatic compounds, because the content of aromatic compounds, due to their toxicity, must be kept as low as possible.
• Preferred mineral oils have a boiling point of at least 230 ° C.
• esters of aliphatic carboxylic acids are much more biodegradable and less toxic than mineral oils.
• esters are: hexyl acetate, 2-ethylhexyl acetate, octyl acetate, iso-octyl acetate, cetyl acetate, dodecyl acetate, tridecyl acetate; butyl butyrate, isobutyl butyrate, amyl isobutyrate, hexyl butyrate, heptyl butyrate, isoheptyl butyrate, octyl butyrate, isooctyl butyrate, 2-ethylhexyl butyrate, nonyl butyrate, butyrate isononyl, cetyl butyrate, isoketyl butyrate; ethyl hexanoate, propyl hexanoate, isopropyl hexanoate, butyl hexanoate, isobutyl hexanoate, amyl hex
• the preferred esters are those of oleic acid such as, for example, isobutyl oleate or isooctyl oleate.
• the oily component can also contain polyols in small amounts such as glycerol.
• the amount of oily constituent used is between 64 and 83% of the total mass of concentrate.
• one uses as fatty substance one or more fatty acids derived from grease, oleic, linoleic and unsaturated C18 acids, mixtures of these acids, or mixtures consisting mainly of fatty ester (s) of glycerol, minority fatty acid (s), and having a melting point greater than approximately 20 ° C, in particular greater than approximately 30 ° C.
• fatty acids derived from grease, oleic, linoleic and unsaturated C18 acids, mixtures of these acids, or mixtures consisting mainly of fatty ester (s) of glycerol, minority fatty acid (s), and having a melting point greater than approximately 20 ° C, in particular greater than approximately 30 ° C.
• the fatty substance chosen is made up of greasy fatty acids, its proportion in the concentrate is advantageously between 0.1 and 20% and in particular between 1 and 15%.
• the fatty substance chosen is oleic acid called olein, its proportion in the concentrate is advantageously between 0.1 and 4%.
• the fatty substance chosen is a mixture consisting mainly (i.e. generally more than 80%) of fatty ester (s) of glycerol and minority fatty acid (s) and having a melting point higher than 20 ° C, its proportion in the concentrate is advantageously between 3 and 20% and in particular between 8 and 11%.
• the acid number I of the fatty substance when the latter comprises acid functions, is conventionally defined as being the number of mg of potassium hydroxide necessary to neutralize the free acid functions contained in 1 g of fatty substance.
• Knowledge of this acid number I of the fatty substance and of the quantity of fatty substance present in the concentrate makes it possible to calculate a value called “acid equivalent” in the present description, and which is equal to the number by number of moles of free acid functions. brought by the fatty substance to the concentrate.
• the quantity of fatty substance used depends on its acid number, and is chosen so that there is, in 100 g of concentrate, an acid equivalent (calculated as explained above) less than 0.01 (100.10 ⁇ 4) moles, and in particular less than 0.005 (50.10 ⁇ 4) moles of free acid functions.
• hydrophilic / hydrophilic balances (HLB) for non-ionic surfactants are theoretical values defined by Griffin (cf. "Peintures et Vernis", P. Grandon et P. Pastour, Ed. Hermann-Paris, p.901-902) and between 1 and 20.
• hydrophilic nonionic surfactant is meant in the present description a surfactant whose balance (HLB) is greater than 10.
• the component (B) has a balance (HLB) less than 12 and, the component (A) has a balance (HLB) greater than or equal to 14.
• Component (A) is preferably present in a proportion of between 1 and 3% of the total mass of concentrate and component (B) preferably represents from 6 to 17% of said total mass. It is advantageous for the mass ratio of component (A) to component (B) to be between 0.15 and 0.18. It is even more advantageous if this ratio is between 0.16 and 0.17.
• component (A) can be a mixture of products each having a suitable balance (HLB) and that component (B) can also be a mixture of products each having a suitable balance (HLB) in the sense of the present invention.
• components (A) are for example esters of fatty acids and of (poly) alcohol, (poly) ethoxylates.
• Components (B) can be, for example, esters of fatty acids and (poly) alcohol, with little or no ethoxylation.
• the solvents used in the concentrates according to the invention are volatile products. They can be alcohols or ether-alcohols. Preferably, they have a boiling temperature below 170 ° C.
• the methyl ether of propylene glycol the methyl ether of dipropylene glycol, the ethyl ether of propylene glycol, the ethyl ether of dipropylene glycol, butanol, ethyl glycol and l ethyl diglycol. It is possible to use a mixture of these solvents.
• the amount of solvent present in the concentrate is between 3% and 6% of the total mass of concentrate.
• the mold release emulsions according to the invention are obtained by diluting a concentrate or a mixture of concentrates according to the invention in water.
• Water can contain various usual additives such as biocidal agents, corrosion inhibitors, anti-freeze, in small proportions.
• the pH of the emulsion is generally between 3 and 7 and more especially between 6 and 6.5.
• the dilution of the concentrates is carried out with a dilution factor of between 0.5 and 2, that is to say that the mass ratio of water / mass of concentrate is preferably between 0.5 and 2 It is particularly advantageous that the dilution factor is between 0.15 and 1.6.
• the mixture of the concentrate and the water can be subjected to an emulsification operation in an apparatus conventionally used as an emulsifier.
• examples of devices which can be used are homogenizers, pin mills, high speed mixers of the Silverson type in which the moving part is placed in a fixed cylinder and high pressure homogenizers.
• the release emulsions can be applied to the surface of the mold, for example by spraying with a normal spraying device such as a manual sprayer, or by means of compressed air or by means of a brush.
• the emulsions according to the invention generally have a viscosity between 35 and 120 cps measured using a Brookfield viscometer of RVT type. They are used at a rate of 9 to 20 g / m2 and preferably from 13 to 17 g / m2 of mold surface.
• the emulsions according to the invention have the particularity of breaking quickly at room temperature. Indeed, the mold is ready for use about 30 minutes after the application of the emulsion. After each release from the mold, it is therefore not necessary to clean the mold before spraying the emulsion again and then pouring the hydraulic binder down.
• Another feature of the emulsions according to the invention is that they are perfectly reversible, that is to say that after freezing and then thawing, simple stirring makes it possible to regenerate the emulsion, the properties of which have not been reduced.
• Another feature of the emulsions according to the invention is that they do not appreciably modify the behavior of the hydraulic binder.
• Example 1 concerns the preparation of concentrates and then emulsions.
• Examples 2 to 5 illustrate properties of the emulsions.
• the oily constituent, the fatty substance, the surfactants and the solvent are introduced into a tank.
• the whole is then brought, with stirring, to a temperature of the order of 40-70 ° C and maintained at this temperature until a homogeneous product is obtained.
• the homogeneous product is then introduced with stirring into water which has previously been brought to the same temperature.
• the emulsion obtained is kept at the same temperature with stirring for one hour and then is cooled to 20 ° C. It is thus ready for use.
• a biocidal agent, a corrosion inhibitor or a conventional additive can optionally be added.
• Montanox 80 ethoxylated sorbitan oleate having a balance (HLB) of 15. It is sold by the company SEPPIC.
• Montanox 85 ethoxylated sorbitan trioleate having a balance (HLB) of 11. It is marketed by the company SEPPIC.
• Montanox 40 ethoxylated sorbitan monopalmitate with a balance (HLB) of 15.6. It is marketed by the company SEPPIC.
• Montanox 65 ethoxylated sorbitan tristearate with a balance (HLB) of 10.5. It is marketed by the company SEPPIC.
• Remcopal 605 ethoxylated nonylphenol oleate having a balance (HLB) of 8.6, sold by the company CECA / GERLAND.
• Emulpour 900 polyethoxyether marketed by the company CECA / GERLAND.
• Dowanol PM Propylene glycol methyl ether sold by the company DOW CHEMICAL. (Boiling point 120.1 ° C)
• Napsol PE1 Ethyl ether of propylene glycol sold by the company BP (Boiling point 129.1 ° C)
• Emulsions were prepared according to Example 1.
• compositions in percentages by mass relative to the total mass of concentrate, as well as their properties.
• the "fouling" line shows the number n of molding / demolding cycles which could have been carried out without having been observed, within the framework of these tests, some of which could be limited to 7 successive demolding taking into account positive results to which they had already led, the appearance of a deposit on the mold.
• the acid equivalent contained in 100 g of these concentrates is between 50.10 ⁇ 4 and 100.10 ⁇ 4 moles of acid functions, with the exception of the latter where it is approximately 42.10 ⁇ 4 moles of acid functions.
• N.B. the test carried out using an emulsion obtained from the concentrate (d) does not allow demolding; the emulsion is also unstable.
• the acid equivalent contained in 100 g of these concentrates is between 50.10 ⁇ 4 and 100.10 ⁇ 4 moles of acid functions.
• the most effective emulsions seem to be those obtained from concentrates whose acid equivalent contained in 100 g of concentrate is less than about 20.10 ⁇ 4 moles of acid functions.
• This example shows that it proves to be advantageous for the oily constituent to be a liquid at the temperature at which the emulsion is intended to be used, that is to say that it has a melting point of less than 10 Approximately ° C, and the fatty substance being a solid or a very viscous liquid at the temperature of use of the invention, that is to say that it has a melting point greater than approximately 20 ° C, in particular above about 30 ° C.
• the viscosity of the emulsions which can then be obtained is generally between approximately 50 and 56 cps at 20 ° C (measured with the Brookfield viscometer).

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• Engineering & Computer Science (AREA)
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• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
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• Agricultural Chemicals And Associated Chemicals (AREA)
• Colloid Chemistry (AREA)

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Cited By (7)

Citations (3)

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• 1994
  • 1994-03-24 FR FR9403577A patent/FR2717731B1/fr not_active Expired - Fee Related
• 1995
  • 1995-02-28 EP EP95420048A patent/EP0678363A3/de not_active Withdrawn

Patent Citations (3)

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