Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
  • C04B24/04—Carboxylic acids; Salts, anhydrides or esters thereof
  • C04B24/06—Carboxylic acids; Salts, anhydrides or esters thereof containing hydroxy groups
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00034—Physico-chemical characteristics of the mixtures
  • C04B2111/00094—Sag-resistant materials

Definitions

• the present invention relates to a method for reducing the creep of a plaster-based element, a plaster-based composition for such an element and a method for manufacturing a plaster-based element with reduced creep. It applies in particular to the production of plasterboards with reduced creep.
• US Patent No. 4,645,548 relates to a process for producing plasterboard, in which tartaric acid or one of its metal salts is used as retarders for hydraulic setting.
• the US patent published under number US 6,352,585 relates to a plaster-based pouring composition intended for use in the dental field.
• This composition is composed of two parts, a first part based on plaster and a second part based on water, one and / or the other of these parts containing at least two acids which are chosen from the group consisting of oxalic, boric, phosphoric, citric, tartaric, sulfuric, acetic, formic, maleic, ascorbic, aspartic acids and their mixtures.
• the two parts are kept separate, then mixed during pouring; the mixture is then allowed to harden.
• Examples 22, 38, 49, 50 of this American patent are described compositions of which the first part consists of 100 g of plaster and the second part comprises
• the Applicant has found that a synergistic effect is produced in terms of anti-creep effect, when a combination of tartaric acid or one or more of its salts is used with l boric acid or one or more of its salts, in a plaster element.
• the present invention relates to a method of reducing creep in a plaster-based element. It applies in particular to plasterboard.
• the method according to the invention comprises the introduction into the plaster-based composition, before the latter sets and hardens to give the element based on plaster, tartaric acid or salt (s). tartaric acid, in an amount greater than 0.001% by weight, preferably greater than 0.01%, relative to the weight of the calcium sulphate hemihydrate contained in the plaster-based composition.
• Another object of the invention is a plaster-based composition which makes it possible to obtain a plaster-based element having reduced creep.
• This composition can in particular be a composition for plasterboard.
• the composition according to the invention comprises, in weight percentages relative to the weight of the calcium sulphate hemihydrate in the composition, from 0.003% to 0.45% of tartaric acid or of salt (s) of tartaric acid and from 0.05% to 0.95% boric acid or boric acid salt (s).
• the invention also relates to a plaster-based element, such as a plasterboard, having reduced creep, which is obtained by hydraulic setting and hardening of the plaster-based composition according to the invention.
• Yet another object relates to the use of tartaric acid or one or more of its salts for the reduction of the creep of a plaster-based element, in particular a plasterboard.
• the invention also relates to a process for the manufacture of a plaster-based element having reduced creep, into which tartaric acid, or one or more of its salts, is introduced, and boric acid, or one or more of its salts, in the plaster-based composition before it sets and hardens to give the plaster-based element.
• plaster-based composition is here meant a conventional plaster composition, that is to say essentially consisting of plaster.
• plaster is meant calcium sulfate semi-hydrate of beta or alpha type.
• This plaster may also contain calcium sulphate in the form of anhydrite.
• tartaric acid here is meant tartaric acid L, D, DL or meso as described in "The Merck Index - eleventh edition".
• mixtures of two or more of these isomers it is possible to use mixtures of two or more of these isomers. It is thus possible to use a mixture of forms L and D, for example according to variable mass ratios from 5/95 to 95/5, advantageously from 30/70 to 70/30. It is also possible to use a mixture of the L, D and meso forms, for example according to variable mass ratios of 10-25 / 10-50 / 25-80, advantageously 10-25 / 10-40 / 50-80.
• the tartaric acid can be used in the form of a salt which can be a metal salt or a quaternary ammonium salt.
• the amount of tartaric acid, or one or more of its salts, introduced into the plaster composition is generally greater than 0.001% by weight relative to the weight of calcium sulphate hemihydrate contained in the plasterboard composition .
• 0.003% to 0.45% and preferably 0.005% to 0 are introduced into the plaster-based composition, in weight percentages relative to the weight of the calcium sulphate hemihydrate present in the composition, 05% tartaric acid or tartaric acid salt (s).
• This embodiment is particularly advantageous, because the combination of these two acids produces a synergy in terms of the anti-creep effect caused.
• the introduction of the additives into the plaster-based composition can be carried out either by dissolving them beforehand in the mixing water, or by mixing them in the form of gypsum powder, or by means of impregnation by soaking the plaster element hardened in an aqueous solution containing the additives.
• air is also introduced into the plaster-based composition by adding a foam.
• This foam may be performed using any suitable foaming agent, for example, the foaming agent of formula ROS0 3 M, as defined on page 14, line 20 to page 15, line 16 of the international application
• a foaming agent comprising an alkali or alkaline earth metal alkyl sulfate is used.
• alkali metal mention may then be made of potassium, lithium and, preferably, sodium.
• alkaline earth metal mention may be made of calcium and magnesium.
• the particularly preferred foaming agent comprises an alkyl sulphate of formula H (C ⁇ 2 ) n OS ⁇ 3 ⁇ M + , in which n varies from
• n m 6 to 16 and the average number of carbon atoms in the composition of alkyl sulphates n m is between 10 and 11, and M is a monovalent cation.
• one or more alkali or alkaline earth metal phosphates are introduced into the plaster-based composition.
• the amount of alkali or alkaline earth metal phosphate introduced is at most 0.5% and preferably less than 0.2% by weight, relative to the mass of calcium sulphate hemihydrate.
• alkali metal of the phosphate mention may be made of sodium, potassium and lithium.
• alkaline earth metal of the phosphate mention may be made of calcium and magnesium.
• the metal is sodium.
• trimetaphosphate is preferably used.
• the particularly preferred metallic phosphate is sodium trimetaphosphate.
• composition based on reduced creep plaster according to the invention comprises, in weight percentages relative to the weight of the calcium sulphate hemihydrate in the composition, more than 0.001%, in particular from 0.003% to 0.45% d tartaric acid or tartaric acid salt (s), and from 0.05% to 0.95% boric acid or boric acid salt (s).
• the plaster-based composition comprises from 0.005% to 0.05% of tartaric acid, or salt (s) of tartaric acid, and from 0.2% to 0 , 8% boric acid, or boric acid salt (s).
• the composition comprises from 0.02% to 0.03% of tartaric acid or of salt (s) of tartaric acid and from 0.4% to 0.7% of boric acid or of salt ( s) boric acid.
• the plaster composition according to the invention preferably comprises, as has been described in relation to the method according to the invention, an alkali or alkaline earth metal phosphate.
• the plaster-based composition according to the invention may also comprise additives conventionally used in plaster-based compositions and well known to those skilled in the art. Mention may be made in this connection of setting accelerators, setting retarders, binding agents, adhesion agents, thinners, water retentants, air entrainers, thickeners, bactericides, fungicides , pH adjusters, reinforcing materials, flame retardants, water repellents and / or fillers.
• the composition according to the invention When used to make a plasterboard, the composition according to the invention has the advantage of not altering the adhesion between the cardboard and the plaster constituting the plate.
• the plaster-based composition according to the invention can advantageously be put in the form of a plate, to give, after hydraulic setting and hardening, a plasterboard with reduced creep.
• the manufacture of a plaster-based element comprises, in addition to the conventional steps, the introduction of tartaric acid, or one or more of its salts, and of boric acid, or of one or more of its salts, in the plaster-based composition, before the setting and the hydraulic hardening of the latter.
• a 0.316 x 0.316 m 2 mini-plate with a thickness of 6.5 mm and a density of 0.78 was prepared from plaster from Carpentras, which is a plaster obtained by flash firing of a natural gypsum with a minimum content. in 80% gypsum.
• This plate is prepared as follows: a foam is prepared by stirring for 1 minute in a Hamilton Beach type foam generator set at a voltage of 55 volts: - 2.5 ml of a solution containing 50 g / 1 of a foaming agent of formula ROS0 3 M, as defined on page 14, line 20 to page 15, line 16 of the international application WO 99 / 08,978.
• the foam is then introduced into a mixture of 400 g of water at a temperature of 50 ° C and 600 g of plaster at a temperature of 22 ° C.
• the plaster paste is placed between two sheets of cardboard. The excess after filling is eliminated.
• the mini-plate is then dried in an oven at a temperature increasing regularly from 100 ° C to 170 ° C in 6 min, then decreasing regularly from 170 ° C to 90 ° C in 16 min until a control plate is obtained. called plate T.
• Plates 1 to 16 were prepared, according to the procedure of Example 1, by previously introducing into the 400 g of water at 50 ° C. the acids indicated in the table below, with the following percentages relative to the weight plaster:
• Creep measurements were carried out on the plates T and 1 to 16 prepared in Examples 1 and 2, according to standard ASTM C 473-95 modified as follows: each plate of width 316 mm (instead of 305 mm) is suspended between two knives distant from a center distance of 300 mm (instead of 584 mm) under the stress equivalent to 1.5 times the dry weight of the plate (760 g). The deflection is measured after 24, 48 and 65 hours. For practical reasons, the creep values noted in the examples correspond to the deflection reached after 65 hours. Creep is measured with an accuracy of 3%.
• This synergistic effect can also be expressed by comparing the improvement in the reduction of creep obtained by the combination of tartaric acid / boric acid, compared to the solution of tartaric acid alone or boric acid alone, for the same overall dosage of additives. .
• a miniplate of 0.316 ⁇ 0.316 m 2 was prepared, having a thickness of 6.5 mm and a density of 0.78, according to the procedure described in Example 1, but using plaster of
• Cilegon which is a plaster obtained by flash cooking of a natural gypsum with a minimum gypsum content of 90%.
• This control plate is called plate T '.
• Plates 23 to 30 were prepared, according to the procedure of Example 6, by previously introducing into the 400 g of water at 50 ° C. the additives indicated in Table VI below with the following percentages relative to the weight of plaster:
• Creep measurements were made on the plates T 'and 23 to 30 prepared in Examples 11 to 12 according to standard ASTM C 473-95 modified according to the description of Example 3.
• the creep values noted in the examples correspond to the deflection reached after 65 hours. Creep is measured with an accuracy of 3%.
• This synergistic effect can also be expressed by comparing the improvement in the reduction of creep obtained by the combination of tartaric acid / sodium trimetaphosphate, compared with the solution of tartaric acid alone or of sodium trimetaphosphate alone, for the same overall dosage of additives.
• plates 31 to 41 were prepared according to the procedure indicated in Example 6, with the following characteristics:
• tartaric acid D is as effective as tartaric acid L and that it also gives rise to a marked improvement in the anti-creep effect when it is combined with boric acid.
• Plates 44 to 53 were prepared, according to the procedure of Example 6, by previously introducing into the 400 g of water at 50 ° C. the acids indicated in Table XIII below, with the following percentages relative to the weight of plaster:
• the mixture of tartaric acid L, D and meso is effective, in particular when the amounts of D and meso are greater than the amount of L.
• a 0.316 x 0.316 m 2 miniplate was prepared having a thickness of 6.5 mm and a density of 0.78, according to the procedure described in Example 1, but from a second batch of plaster of Cilegon , which is a plaster obtained by flash firing of a natural gypsum with a minimum gypsum content of 90%.
• This control plate is called plate T ''.
• a 0.316 x 0.316 m 2 mini-plate with a thickness of 12.5 mm and a density of 0.80 was prepared from plaster from Ottmarsheim, which is a plaster obtained by indirect baking in a rotary kiln.
• synthetic gypsum from the desulphurization of thermal power plant fumes with a minimum gypsum content of 98%.
• This plate is prepared as follows: a foam is prepared by stirring for 1 minute in a Hamilton Beach type foam generator set at a voltage of 55 volts:
• the foam is then introduced into a mixture of 400 g of water at a temperature of 50 ° C and 600 g of plaster at a temperature of 22 ° C.
• the plaster paste is placed between two sheets of cardboard. The excess after filling is eliminated.
• the mini-plate is then dried in an oven at a temperature increasing regularly from 100 ° C to 170 ° C in 6 min, then decreasing regularly from 170 ° C to 90 ° C in 16 min. Once dry, the plate is immersed in 5000 ml of water. distilled water until constant weight gain and then dried at 45 ° C until a control plate called T plate '' is obtained.
• Plate 62 was prepared, according to the procedure of Example 18, by previously introducing 28,000 tartaric acid L into the 5000 g of distilled water.
• Example 20
• Creep measurements were made on the plates T '' 'and 62 prepared in Examples 18 and 19, according to standard ASTM C 473-95 modified as follows: each plate of width 316 mm (instead of 305 mm) is suspended between two knives distant from a center distance of 300 mm (instead of 584 mm) under the stress equivalent to 1.5 times the dry weight of the plate (760 g). The deflection is measured after 24, 48 and 65 hours. For practical reasons, the creep values noted in the examples correspond to the deflection reached after 65 hours. Creep is measured with an accuracy of 3%.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Cosmetics (AREA)
• Producing Shaped Articles From Materials (AREA)

Applications Claiming Priority (3)

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• 2002
  • 2002-12-06 FR FR0215427A patent/FR2848207A1/fr active Pending
• 2003
  • 2003-12-02 BR BR0316578-7A patent/BR0316578A/pt not_active IP Right Cessation
  • 2003-12-02 AU AU2003298389A patent/AU2003298389A1/en not_active Abandoned
  • 2003-12-02 EP EP03796134A patent/EP1569877A2/de not_active Withdrawn
  • 2003-12-02 MX MXPA05006045A patent/MXPA05006045A/es unknown
  • 2003-12-02 KR KR1020057010267A patent/KR20050085409A/ko not_active Application Discontinuation
  • 2003-12-02 US US10/537,397 patent/US20060048680A1/en not_active Abandoned
  • 2003-12-02 WO PCT/FR2003/003556 patent/WO2004052802A2/fr not_active Application Discontinuation
  • 2003-12-02 CN CNA2003801052516A patent/CN1777564A/zh active Pending

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