(Melt-) extrusion process for the preparation of alkali metal carbonate, bicarbonate and sesquicarbonate formulations using a melted functionalizing agent

Abstract

The present invention relates to a process for preparing a formulation comprising an alkali metal salt selected from the group consisting of alkali metal bicarbonate salts, alkali metal carbonate salts, alkali metal sesquicarbonate salts and combinations thereof, wherein said process comprises the step of extruding a paste-like composition comprising a functionalizing agent and the metal salt. The invention furthermore relates to a formulation obtainable from said process and to the use of this formulation in various applications such as in plastic foaming or in food and feed leavening compositions.

Claims

1. A process for preparing a formulation comprising an alkali metal salt selected from the group consisting of alkali metal bicarbonate salts, alkali metal carbonate salts, alkali metal sesquicarbonate salts and combinations thereof, wherein said process comprises the steps of: (a1) melting a functionalizing agent to a temperature above the melting point of the functionalizing agent to obtain a melted functionalizing agent, and mixing the melted functionalizing agent with the alkali metal salt to obtain a paste-like composition; or (a2) mixing the functionalizing agent and the alkali metal salt to obtain a mixture, and heating the mixture to a temperature above the melting point of the functionalizing agent to melt the functionalizing agent within the mixture and to obtain a paste-like composition; or (a3) mixing the functionalizing agent and the alkali metal salt to obtain a mixture, and, to obtain the formulation, (b1) extruding or melt-extruding the paste-like composition obtained in step (a1) or (a2), or (b2) melt-extruding the mixture obtained in step (a3) at a temperature above the melting point of the functionalizing agent to melt the functionalizing agent to obtain a paste-like composition during extrusion, wherein the paste-like composition undergoing extrusion comprises at least 25% by weight of said alkali metal salt, based on the total weight of the composition undergoing extrusion, and the functionalizing agent, wherein the functionalizing agent is selected from the group consisting of oils, fats, resin acids and esters and salts of oils, fats, resin acids and esters, fatty acids, fatty acid esters, and fatty acid salts other than calcium stearate, waxes, shellac, poly(methyl)methacrylates, and combinations thereof, wherein the waxes comprise from 16 to 46 carbons, wherein at steps (a1) or (a2) or (a3), the weight ratio of the functionalizing agent is at least 30 parts per 100 parts of the alkali metal salt.

2. The process of claim 1, wherein at steps (a1) or (a2) or (a3), the weight ratio of the functionalizing agent is at least 35 parts per 100 parts of the alkali metal salt; and wherein at step (b1) or (b2), the formulation is in form of a powder, filaments or granules, comprising alkali metal salt particles and the functionalizing agent.

3. The process of claim 1, comprising after step (b1) or (b2) the step: (c) cooling the formulation to below the melting temperature of the functionalizing agent to obtain a cooled formulation in form of a powder, or cooled filaments or cooled granules of the alkali metal salt and the functionalizing agent.

4. The process according to claim 2, wherein the filaments or granules are further milled.

5. The process of claim 1, wherein the melting point of the functionalizing agent is at least 0° C., and is at most 140° C.

6. The process according to claim 1, wherein the functionalizing agent is, or comprises, an oil and/or a wax, and the oil comprises 12 to 22 carbons.

7. The process according to claim 1, wherein the functionalizing agent is, or comprises, a fatty acid that is a compound according to formula (I)
R—COOH  (I) wherein R is a saturated or unsaturated C6 to C32 alkyl group.

8. The process according to claim 1, wherein the functionalizing agent is, or comprises, a resin acid that is a tricyclic diterpene carboxylic acid.

9. The process according to claim 1, wherein the functionalizing agent is, or comprises, beeswax.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) As mentioned above, the present invention relates to a process for preparing a formulation comprising an alkali metal salt selected from the group consisting of alkali metal bicarbonate salts, alkali metal carbonate salts, alkali metal sesquicarbonate salts and combinations thereof, wherein said process comprises the steps of:

(2) (a1) melting a functionalizing agent to a temperature above the melting point of the functionalizing agent to obtain a melted functionalizing agent, and mixing the melted functionalizing agent with the alkali metal salt to obtain a paste-like composition; or
(a2) mixing the functionalizing agent and the alkali metal salt to obtain a mixture, and heating the mixture to a temperature above the melting point of the functionalizing agent to melt the functionalizing agent within the mixture and to obtain a paste-like composition; or
(a3) mixing the functionalizing agent and the alkali metal salt to obtain a mixture,
and, to obtain the formulation,
(b1) extruding or melt-extruding the paste-like composition obtained in step (a1) or (a2), or
(b2) melt-extruding the mixture obtained in step (a3) at a temperature above the melting point of the functionalizing agent to melt the functionalizing agent to obtain a paste-like composition during extrusion,
wherein the paste-like composition undergoing extrusion comprises at least 25% by weight of said alkali metal salt, based on the total weight of the composition undergoing extrusion, and the functionalizing agent.

(3) Preferably, the paste-like composition undergoing extrusion comprises at least 30%, more preferably at least 50%, even more preferably at least 60%, even more preferably at least 65%, even more preferably at least 70%, or at least 80% by weight of the alkali metal salt.

(4) Preferably, at steps (a1) or (a2) or (a3) of the process of the present invention, the weight ratio of functionalizing agent is at least 20, more preferably at least 25, even more preferably at least 30, and even more preferably at least 35 parts per 100 parts of alkali metal salt. In one embodiment, the ratio of the weight of the functionalizing agent to the weight of the alkali metal salt in the composition undergoing extrusion is greater than 0.25, or at least 0.3, or at least 0.4, or at least 0.5.

(5) Preferably, at step (b1) or (b2) the formulation is in the form of a powder, filaments or granules, comprising alkali metal salt particles and functionalizing agent.

(6) Preferably, the process of the present invention comprises after step (b1) or (b2) the step: (c) cooling the formulation to below the melting temperature of the functionalizing agent to obtain a cooled formulation in form of a powder, or cooled filaments or cooled granules of the alkali metal salt and the functionalizing agent.

(7) In another embodiment, the process comprises melting the functionalizing agent, mixing the melted functionalizing agent with the alkali metal salt to obtain a first mixture, solidifying the first mixture, e.g., by cooling the first mixture, and extruding or melt-extruding the solidified first mixture.

(8) In yet another embodiment, the process comprises (i) mixing the functionalizing agent with a solvent (e.g., water) to obtain a dispersion, (ii) heating the dispersion to a temperature greater than the melting temperature of the functionalizing agent so as to obtain an emulsion, (iii) mixing the emulsion with the alkali metal salt to obtain a paste-like composition, (iv) extruding the paste-like composition, and (v) optionally removing the solvent.

(9) In yet another embodiment, the process comprises (i) mixing the functionalizing agent with a solvent (e.g., water) having a temperature greater than the melting temperature of the functionalizing agent so as to obtain an emulsion, (ii) mixing the emulsion with the alkali metal salt to obtain a paste-like composition, (iii) extruding the paste-like composition, and (iv) optionally removing the solvent.

(10) Preferably, the functionalizing agent is selected from the group consisting of oils, fats, resin acids and esters and salts thereof, fatty acids and esters and salts thereof, soaps, waxes, shellac, poly(methyl)methacrylates, and combinations thereof.

(11) Shellac is a natural resin produced by Laccifer lacca, and represents a mixture of aliphatic alicyclic hydroxyl acids and aleuritic and shelloic acids.

(12) Poly(methyl)methacrylates suitable for use in the present invention include Eutragit® RL 30D from Evonik.

(13) The melting point of the functionalizing agent is preferably at least 0° C., and/or is at most 140° C., preferably at most 90° C.

(14) Preferably, the paste-like composition comprises alkali metal salt and 0.1-60% by weight, or 0.5-60% by weight, or 1-60% by weight, or 3-60% by weight, or 5-60% by weight, or 7-60% by weight, or 10-60% by weight, or 15-60% by weight, or 17%-60%, or 20%-57%, or even 23%-54% by weight of a fat, an oil, a resin acid or a salt thereof, a fatty acid or a salt thereof, a soap, or a wax, or a combination thereof as the functionalizing agent thereof, based on the total weight of the composition undergoing extrusion. If present in an amount of less than 0.1% by weight, or less than 0.3% by weight, or less than 0.5% by weight, or less than 1% by weight, or less than 3% by weight, or less than 5% by weight, or less than 7% by weight, or less than 10% by weight, or less than 15% by weight, or even less than 17% by weight, the functionalizing agent is less efficient in terms of the provision of a paste-like composition. More than 60% by weight of the functionalizing agent in the paste-like composition is disadvantageous for cost reasons.

(15) Preferably, the functionalizing agent is, or comprises, an oil and/or a wax, and the oil comprises 12 to 22 carbons, and/or the wax comprises from 16 to 46 carbons.

(16) An example for an oil used in the present invention is soybean oil which comprises linoleic acid, oleic acid, stearic acid, and palmitic acid. The soybean oil can also be hydrogenated (e.g., Drapex 392).

(17) In a further preferred embodiment of the present invention, the functionalizing agent is, or comprises, a fatty acid that is a compound according to formula (I)
R—COOH
wherein R is a saturated or unsaturated C6 to C32 alkyl group, preferably a C12 to C18 alkyl group, more preferably a C12 to C16 alkyl group. Typical fatty acids used as the functionalizing agent in the present invention include stearic acid, isostearic acid, lauric acid and palmitic acid. Typical functionalizing agents used in the process of the present invention comprising a fatty acid are stearine and palm oil.

(18) In a further preferred embodiment of the present invention, the functionalizing is or comprises an ester of a fatty acid. An example for an ester of a fatty acid used as functionalizing agent in the present invention is glycerol monstearate.

(19) In a further preferred embodiment of the present invention, the functionalizing agent is, or comprises, a resin acid. Generally, the resin acid to be used as functionalizing agent in accordance with the present invention is one of the resin acids known in the art. The resin acids refer to mixtures of related carboxylic acids, preferably abietic acid, found in tree resins. Typically, resin acids have the basic skeleton of three fused rings with an empirical formula C.sub.19H.sub.29COOH. Preferred the resin acid is a tricyclic diterpene carboxylic acid, more preferable belonging to the abietane diterpene group. Preferred resin acids are abietic-type acids, e.g., selected from the group consisting of abietic acid (abieta-7,13-dien-18-oic acid), neoabietic acid, dehydroabietic acid, and palustric acid. Also suitable are pimaric-type acids, selected from the group consisting pimaric acid (pimara-8(14),15-dien-18-oic acid), levopimaric acid, or isopimaric acid. Such acids are available from natural sources or via chemical synthesis as e.g., known from US 2014/0148572 A1.

(20) A derivative containing resin acids that may be used in accordance with the present invention is tall oil. Tall oil (also called liquid rosin) is obtained as a by-product of the Kraft process of wood pulp manufacture. Crude tall oil contains rosin, resin acids (mainly abietic acids and its isomers), fatty acids (mainly palmetic, and oleic), fatty alcohols, sterols and alkyl hydrocarbon derivatives. Most preferred abietic acid, pimaric acid and their salts, in particular the sodium salts, respectively are used as functionalizing agent in accordance with the present invention.

(21) In a further preferred embodiment of the present invention, the functionalizing agent is, or comprises, a wax. Waxes are chemical compounds that are malleable near ambient temperatures. Characteristically, they melt above 45° C. to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, nonpolar solvents. All waxes are organic compounds, both synthetically and naturally occurring, which comprise or consist of long alkyl chains. Natural waxes may contain esters of carboxylic acids and long chain alcohols or mixtures of substituted hydrocarbons, such as long chain fatty acids and primary alcohols. Examples for natural waxes used as functionalizing agents in the present invention are beeswax and carnauba wax. Synthetic waxes such as paraffin wax, are long-chain hydrocarbons lacking functional groups. An example for a wax used in the present invention is beeswax, wherein a major component is the ester myricyl palmitate which is an ester of triacontanol and palmitic acid. Particularly preferred is beeswax. Another wax that can be used in the present invention comprises or consists of the compound having the structure C.sub.24-54—(C═O)—C.sub.24-54.

(22) Preferably, the alkali metal salt used at step (a1) or (a2) or (a3) is made of particles, and said particles have a medium particle size (D50 in weight) of less than 300 μm, more preferably less than 200 μm, even more preferably less than 130 μm. The particles typically have a medium particle size (D50 in weight) of at least 10 μm, or at least 20 μm, or at least 30 μm, or at least 40 μm, or at least 50 μm. The medium particle size (D50 in weight) of the particles may range from 10-300 μm, or 20-200 μm, or 30-150 μm, or 50-130 μm. The particle size distribution can be determined according to ISO 13320. For example, the weight-average diameter D50 value can be measured by laser diffraction and scattering on a Malvern Mastersizer S particle size analyser using an He—Ne laser source having a wavelength of 632.8 nm and a diameter of 18 mm, a measurement cell equipped with a backscatter 300 mm lens (300 RF), and MS 17 liquid preparation unit, and an automatic solvent filtration kit (“ethanol kit”) using ethanol saturated with the alkali metal salt (wet method).

(23) Preferably, the alkali metal salt is a bicarbonate salt or a sesquicarbonate salt, in particular sodium bicarbonate or sodium sesquicarbonate. Particularly preferred is sodium bicarbonate.

(24) Preferably, a third compound selected among a mineral compound, an organic compound, and mixtures thereof, is added to the alkali metal salt or to the functionalizing agent to obtain the paste-like composition.

(25) Preferably, the mineral compound is silica, sodium silicate or sodium silicate hydrate, calcium carbonate, and/or wherein the organic compound is citric acid.

(26) Preferably, at steps (a1) or (a2) or (a3) the weight ratio of functionalizing agent and alkali metal salt is at most 100 parts, preferably at most 70 parts, more preferably at most 60 parts, even more preferably at most 55 parts of the functionalizing agent per 100 parts of alkali metal salt.

(27) In the process for preparing an alkali metal bicarbonate formulation by extrusion, all suitable extrusion procedures as known in the art can be used. Preferably, the extrusion is performed on a screw extruder, e.g., a single screw extruder or a twin screw extruder.

(28) Preferably, the cooled filaments or granules are in a step (d) subsequently cut into pieces or grinded at a temperature below the melting temperature of the functionalizing agent.

(29) The process of the present invention allows the control of the shape and size of the resulting formulation, which can be obtained as filaments or granules as described above. The ability to control shape and size of the alkali metal bicarbonate formulation of the present invention is advantageous with respect to the various applications of alkali metal bicarbonates as known in the art.

(30) The present invention furthermore relates to an alkali metal salt formulation obtainable by an extrusion process as described above, wherein the formulation comprises alkali metal salt and a functionalizing agent, and wherein the formulation is in the form of a powder, filaments or granules, wherein the granules have a spherical, cubic or cylindrical shape. Preferably, the filaments or granules obtained from the process of the present invention have a diameter of at least 100 μm, preferably of at least 200 μm, more preferably of at least 500 μm, even more preferably of at least 1 mm.

(31) Powders obtained from the extrusion process or by further milling the filaments or granules obtained from the extrusion process comprise particles with a medium particle size (D50 in weight) in the range of 1 μm to 2 mm, preferably from 10 μm to 500 μm. The particle size distribution can be determined according to ISO 13320.

(32) The present invention furthermore relates to an alkali metal salt formulation (preferably obtainable by an extrusion process as described herein) comprising an alkali metal bicarbonate and a functionalizing agent as described herein. The formulation is preferably in the form of a powder, filaments or granules as described herein, wherein the granules have a spherical, cubic or cylindrical shape.

(33) Preferably, the formulation comprises at least 40% by weight of an alkali metal bicarbonate, less than 10% by weight of an alkali metal carbonate, less than 10% by weight of water, and 0.1-60% by weight, or 0.5-60% by weight, or 1-60% by weight, or 3-60% by weight, or 5-60% by weight, or 7-60% by weight, or 10-60% by weight, or 15-60% by weight, or 17%-60%, or 20%-57%, or even preferably 23%-54% by weight of a resin acid or an ester or a salt thereof, a fatty acid or an ester or a salt thereof, or a wax, each based on the total amount of the alkali metal salt formulation.

(34) More preferably, the formulation comprises at least 45%, even more preferably at least 50%, even more preferably at least 60%, even more preferably at least 65%, even more preferably at least 70% by weight of the alkali metal bicarbonate, based on the total amount of the alkali metal salt formulation.

(35) Preferably, the formulation is in the form of filaments or granules having a diameter of at least 100 μm, preferably of at least 200 μm, more preferably of at least 500 μm, even more preferably of at least 1 mm.

(36) Preferably, the formulation is in the form of filaments or granules having a diameter of at most 100 mm, preferably of at most 50 mm, more preferably of at most 5 mm, even more preferably of at most 2 mm. The length-to-diameter ratio of the filaments or granules may range from about 0.4 to about 4. Preferably, the alkali metal salt in the formulation of the present invention is a bicarbonate or a sesquicarbonate salt, particularly sodium bicarbonate or sodium sesquicarbonate. Particularly preferred is sodium bicarbonate.

(37) The formulation obtainable by the process of the invention shows an excellently increased dissolution time. The formulation of the present invention shows a dissolution time of at least 30 seconds, preferably at least 100 seconds, more preferably at least 200 seconds.

(38) The formulation obtainable from the processes of the invention also show excellent CO.sub.2 release properties. CO.sub.2 release of the formulation obtained from the process of the present invention begins at a temperature of at least 120° C., preferably at a temperature of at least 125° C., more preferably at a temperature of at least 130° C., even more preferably at a temperature of at least 135° C., and particularly preferably at a temperature of at least 140° C., as determined by the TGA method described above. The CO.sub.2 release typically has its maximum at a temperature of at least 150° C., preferably at a temperature of at least 155° C., more preferably at a temperature of at least 160° C., even more preferably at a temperature of at least 165° C., and particularly preferably at a temperature of at least 170° C., as determined by the TGA method described above.

(39) The advantageous properties of the formulation as described above and as obtainable by the process of the invention make it possible to envisage various applications for this alkali metal bicarbonate formulation. The present invention therefore further relates to the use of the alkali metal salt formulation obtainable from the process described above as detergent, as blowing or foaming agent for polymers, as agent for pharmaceutical applications, as exfoliating agent, as anti-parasitic agent, as cosmetic agent such as deodorizing agent, as leavening agent for food and feed, as agent for flue gas cleaning, as food and feed supplement additive or food and feed pH buffer, in particular for aquatic animals or for fish.

(40) The following examples are given by way of non-limiting illustration of the present invention, and variations thereof that are readily accessible to a person skilled in the art.

EXAMPLES

Example 1

(41) Different weight ratios of palmoil, stearine and beeswax in relation to sodium bicarbonate were tested with respect to their ability to form paste-like compositions suitable for extrusion. The compositions were produced according to the following procedure.

(42) Palmoil, stearine and beeswax, respectively, were heated in a magnetically stirred, double-jacketed glass beaker to a temperature of 65° C. Sodium bicarbonate (SOLVAY BICAR® TEC 0/13) was added to the melted functionalizing agent and mixed by means of stirring until a homogenous composition was formed.

(43) The respective compositions 1 to 5 are shown in the following Table 1.

(44) TABLE-US-00001 TABLE 1 Functionalizing Functionalizing agent NaHCO.sub.3 Weight ratio Composition agent (FA) [g] [g] FA:NaHCO.sub.3 1 Palmoil 10 40 0.25 2 Palmoil 20 40 0.5 3 Stearine 20 80 0.25 4 Beeswax 10 40 0.25 5 Beeswax 20 40 0.5

(45) The compositions 1 to 5 were then transferred into a syringe of 20 mm diameter and an exit orifice (nozzle) of 1.8 mm internal diameter, and extrusion was performed at room temperature (20-30° C.) or at elevated temperatures of 60-65° C. The observations as indicated in the following Table 2 were made.

(46) TABLE-US-00002 TABLE 2 Temperature Formulation [° C.] Observations 1 room temperature Extrusion not possible because composition was too hard, i.e., not paste-like as defined above 1 60-65° C. Extrusion not possible because composition was too hard, i.e., not paste-like 2 room temperature Extrusion worked well 3 60-65° C. Extrusion worked well 4 60-65° C. Extrusion not possible because paste was too hard, i.e., not paste-like as defined above 5 60-65° C. Extrusion worked well

(47) The above results illustrate that a weight ratio of functionalizing agent:alkali metal salt of greater than 0.25 is preferred in order to obtain a paste-like composition that is suitable for extrusion.

Example 2

(48) A formulations of sodium bicarbonate and stearine (formulation 1) and a formulation of sodium bicarbonate and beeswax (formulation 2) were prepared according to the following procedure.

(49) 20 g of stearine (formulation 1) and beeswax (formulation 2), respectively, were heated in a magnetically stirred, double-jacketed glass beaker to a temperature of 65° C. 80 g (formulation 1) or 40 g (formulation 2) sodium bicarbonate (SOLVAY BICAR® TEC 0/13) was added to the melted FA and mixed until a homogenous paste-like composition was formed. The paste-like composition was transferred into a syringe of 20 mm diameter and an exit orifice (nozzle) of 1.8 mm internal diameter, and extrusion was performed resulting in the formation of filaments of the sodium bicarbonate and the respective plasticizer (diameter 1.8 mm).

(50) The composition of formulations 1 and 2 is given in the following Table 3:

(51) TABLE-US-00003 TABLE 3 Concentration Functionalizing [g of FA on kg NaHCO.sub.3 Na.sub.2CO.sub.3 Formulation agent (FA) formulation] [g/kg] [g/kg] 1 Stearine 278.27 709.82 11.91 2 Beeswax 513.33 470.82 15.85

(52) Dissolution time and CO.sub.2 release temperature of formulations 1 and 2 were determined as described above. The results are given in the following Table 4.

(53) TABLE-US-00004 TABLE 4 TGA CO.sub.2 TGA CO.sub.2 release release beginning maximum Functionalizing Dissolution temperature temperature Formulation agent Time [s] [° C.] [° C.] 1 Stearine >1772 162.3 175.4 2 Beeswax >2017 145.8 174.8 TGA method: 35 to 250° C./10° C./min

(54) The results show that high dissolution times of more than 1770 seconds can be achieved when stearine or beeswax is used as the functionalizing agent in the process of the present invention.

(55) The CO.sub.2 release begins at a temperature of approximately 146 and 162° C., respectively, and has its maximum at approximately 175° C. for both functionalizing agents.

Example 3: Decomposition Kinetics

(56) The following Table 5a shows 16 sodium bicarbonate products (entries 1 to 16) comprising different functionalizing agents that were obtained by the extrusion process according to the invention.

(57) The sodium bicarbonate products according to entries 1, 3 to 10 of Table 5a were obtained by means of a continuous mixing/extrusion process. Mass flow amounts of bicarbonate were between 10 and 30 kg/h. Functionalizing agents were added as indicated in the Table 5a (entries 3 10). The temperature applied in the process was between 30 and 100° C. The residence time was between 2 to 20 minutes.

(58) The sodium bicarbonate product according to entry 2 of Table 5a was obtained by means of the above described extrusion process, wherein the resulting product was further milled using a Planetary ball mill.

(59) The sodium bicarbonate products according to entries 11 to 16 of Table 5a were obtained by means of a continuous mixing/extrusion process, which was carried out as described above for the products according to entries 3 to 10. The resulting products were further milled using a Planetary ball mill, providing the products according to entries 11 to 16 of Table 5a.

(60) The reference product is SOLVAY BICAR® TEC 0/13 (Table 5, entry 17).

(61) TABLE-US-00005 TABLE 5a Functionalizing Agent Content FA Entry Process (FA) [wt. %] 1 Extrusion Stearic acid 20 2 Extrusion + Stearic Acid 20 Milling 3 Extrusion Beeswax 10 4 Extrusion Glycerol Monstearate 10 5 Extrusion Stearic acid 5 7 Extrusion Carnauba wax 10 7 Extrusion Hydrogenated soybean 5 oil (Drapex 392) 8 Extrusion Lauric acid 10 9 Extrusion Isostearic acid 10 10 Extrusion Eutragit RL 30D 3 11 Extrusion + Beeswax 10 Milling 12 Extrusion + Glycerol Monstearate 10 Milling 13 Extrusion + Stearic acid 10 Milling 14 Extrusion + Carnauba wax 10 Milling 15 Extrusion + Eutragit RL 30D 4 Milling 16 Extrusion + Lauric acid 10 Milling 17 BICAR ® — —

(62) Decomposition kinetics of the sodium bicarbonate products indicated in Table 5a were measured by means of a thermal balance analyzer (Moisture Analyzer Mettler Toledo HX204). 2 to 3 g of the product was uniformly spread on an aluminum pan, and put in the thermal balance analyzer, which was rapidly heated to the desired temperature of 140° C.

(63) t95% [s] is the decomposition time at a temperature T (i.e., 140° C.) where 95% of the final loss is reached at the desired temperature; a [% wt/s] is the line slope between the point of 15% and 95% of the decomposition kinetics at a temperature T (i.e., 140° C.).

(64) The results are given in the following Table 5b.

(65) TABLE-US-00006 TABLE 5b Entry 140° C. t95 [s] 140° C. a [% wt/s] 1 2145 0.015 2 2480 0.008 3 2430 0.014 4 2540 0.014 5 2350 0.017 6 3560 0.009 7 2435 0.013 8 2935 0.014 9 5005 0.007 10 1215 0.027 11 2715 0.012 12 1635 0.021 13 1330 0.025 14 2480 0.013 15 1335 0.025 16 2035 0.017 17 1070 0.030

(66) All the sodium bicarbonate products comprising a functionalizing agent show increased gas release times at a temperature of 140° C. compared to the reference SOLVAY BICAR® TEC 0/13.

(67) CO.sub.2 release temperatures of the products according to entries 5 to 7 and 17 of Table 5a were determined as described above. The results are shown in the following Table 5c:

(68) TABLE-US-00007 TABLE 5c TGA CO.sub.2 release TGA CO.sub.2 release beginning temperature maximum Entry [° C.] temperature [° C.] 5 157 164 6 152 171 7 131 165 17 120 152 TGA method: 35 to 250° C./10° C./min

(69) The results show that both the CO.sub.2 release beginning temperature and the CO.sub.2 release maximum temperature are increased in the products comprising a functionalizing agent compared to the SOLVAY BICAR® TEC 0/13 standard which does not comprise a functionalizing agent.