FR2575755A1 - Process for the preparation of concentrated aqueous solutions of anionic products of melamine/phenol/formaldehyde condensation, solutions obtained and their use as additives for building materials - Google Patents

Abstract

Anionic products of melamine/phenol/formaldehyde condensation, containing sulphonic acid groups. The invention relates particularly to a process for the preparation of stable concentrated aqueous solutions of such condensation products, which have a solids content of at least 50 % by weight, which involves a number of successive condensation stages under varied temperature, duration, proportions and pH conditions. The solutions obtained are used especially as additives for mortars.

Description

 The invention relates to a process for the production of concentrated aqueous solutions of anionic melamine / phenol / formaldehyde condensation products containing sulfonic acid groups, the solutions obtained by this process, and their use as additives for building materials.

Several patents already describe the manufacture of water-soluble condensation products containing sulfonic acid groups
- US Patent No. 2,730,516 describes products having the special property of not hardening under the action of heat. Therefore, they are used as protective stiff necks, thickeners or emulsifiers. However, the aqueous solutions of these products can only be produced with a solid active ingredient content of at most 25% by weight.
- French patent NO 1,510,314 describes the preparation of aqueous solutions of condensation products based on amino-s-triazine having at least two amino groups, formaldehyde and sulfite of alkali metals, used in materials of construction.

 Examples D and E of this patent mention the synthesis of products having a solid content of 50% by weight; however, there is a need to isolate sulfonic acid beforehand.

- French patent NO 2,252,361 describes the manufacture of highly concentrated aqueous solutions of anionic melamine / formaldehyde condensation products with sulfonic acid groups, by condensation in several stages at different pH values. The highly concentrated aqueous solutions described have a maximum solid content of 50% by weight, and are used in building materials. This patent has the advantage, compared to the two other mentioned above, of directly leading to the production concentrated products (maximum -50% solid matter) thanks to a relatively simple and inexpensive procedure,
It is proposed, according to the invention, to provide a very simple process making it possible to obtain anionic melamine / phenol / formaldehyde condensation products with sulfonic acid groups, in the form of highly concentrated aqueous solutions, said solutions having a solid content. at least 50% by weight.

More specifically, the invention relates to a method characterized by the following steps
a) heating to a temperature between 60 and 100 ° C., in the presence of a basic catalyst, an aqueous solution containing phenol, formaldehyde or a formaldehyde donor, and a metabisulfite in a molar ratio of 1/0, 9-1.1 / 0.45-0.55;
b) the condensation of the product obtained in (a) is continued, in the presence of a basic catalyst, with formaldehyde or a formaldehyde donor, at a temperature between 800C and the boiling temperature using an amount of formaldehyde relative to the starting phenol such that the formaldehyde / phenol molar ratio is in the range of 0.9 to 1.1;
c) then continuing, in the presence of a basic catalyst, to condense at a temperature close to boiling with melamine, formaldehyde or a formaldehyde donor and a metabisulfite in a molar ratio comprised in the range of 1, 9-8 / 5.8-24.8 / 0.94.4 relative to the starting phenol, until the sulfite is no longer detectable,
d) the pH of the mixture is then adjusted using a concentrated mineral acid to a value between 4.5 and 5.5 and the condensation is continued for approximately 30 to 120 minutes, at a temperature between 30 and 60 "C;
e) the pH is then adjusted to approximately 8-10 using a concentrated aqueous solution of strong mineral base, so as to obtain a concentrated and stable aqueous solution containing at least 50% by weight of solid material.

 Typically, the solid content of the solutions obtained is in the range of 50 to 60% by weight.

The invention also relates to a variant of this method in which steps (b) and (c) are modified as follows
b ') the condensation of the product obtained in (a) with melamine and formaldehyde or a formaldehyde donor is continued, in the presence of a basic catalyst, at a temperature between 80 ° C. and the boiling point , in a molar ratio in the range of 1.9-8 / 6.8-2558 relative to the starting phenol;
c ') then continues, in the presence of a basic catalyst, to condense with a metabisulfite in a molar ratio of 0.9 to 4.4 relative to the starting phenol, at a temperature close to boiling, until that the sulfite is no longer detectable.

To further improve the storage stability of the product from step (e), the following optional step can be performed
f) continuing to condense at a pH of about 8-10, at a temperature between 70 and 90 C, for a maximum of 60 minutes.

This increased stability will be further enhanced by proceeding, after step (f), to the next additional optional step.
g) the pH is adjusted to approximately 10.5-11 using an aqueous solution of a strong mineral base.

 The invention also relates to the concentrated solutions obtained by the process of the invention.

 As basic catalyst, sodium hydroxide or potassium hydroxide in concentrated aqueous solutions will preferably be used. It is possible, for example, to use from 1 to 20 mole percent, in particular from 1 to 10 mole percent of catalyst relative to the phenol.

 In the process, formaldehyde or a formaldehyde donor, such as paraformaldehyde, can be used.

Formaldehyde is preferably used in the form of an aqueous solution at 44 percent by weight.

 As metabisulfite, alkali metal metabisulfites can be used. Preferably, sodium metabisulfite is used. As an indication, step (a) can last from 30 to 120 minutes approximately and step (b) can last from 30 to 90 minutes approximately.

 Preferably, in step (c), the melamine / formaldehyde / metabisulphite molar ratio relative to the starting phenol is within the range of 3.5-4.5 / 10-14 / 1.6-2.5. In step (c), if a melamine / formaldehyde / metabisulfite ratio is used, relative to the starting phenol, below the lower limit indicated (i.e. 1.9 / 5.8 / 0.9), it becomes impossible to synthesize a product with a concentration of at least 50% by weight. If, on the other hand, said ratio exceeds the upper limit indicated (namely 8 / 24.8 / 4.4), the product obtained loses its effectiveness as an additive for mortars. Similar remarks apply to the molar ratios mentioned in steps (b ') and (c').

 Preferably, in step (d), sulfuric acid is used as concentrated mineral acid, but other acids can also be used, for example hydrochloric acid. In step (d), if the condensation time is less than 30 minutes, the final product has practically no effectiveness as an additive for mortars.

If the condensation time exceeds 120 minutes, there is a risk of obtaining a gelled product which cannot be used and which does not meet the criteria of the invention.

 In step (f) if the condensation time exceeds 60 minutes, there is a risk of obtaining a product that is too viscous as it is, and therefore difficult to use.

 In the optional step (g), the strong base is preferably soda, but other bases, such as potash, may also be used.

 Thus, according to the invention, by using inexpensive raw materials, namely: melamine, formaldehyde, phenol, metabisulfite, sulfuric acid, alkaline liquor, it is possible, thanks to a relatively simple procedure, to obtain concentrated aqueous solutions of anionic melamine / phenol / formaldehyde condensation containing sulfonic acid groups.

 These concentrated solutions can be, by simple dilution, brought to any lower solid content. The stability of the concentrated solutions according to the invention is satisfactory.

The process of the invention has the advantages of not requiring the isolation of intermediate products, an operation which always puts a strain on the cost of the final product, and of directly giving a concentrated solution of product. This last point constitutes an important economic advantage because
- for the same quantity transported, less water and more solid material are transported, which translates into a reduction in the cost of transport when shipping to distant countries.

 - a concentrated product allows a reduction in the doses of use, therefore a reduction in the sizing of the packaging which, itself, leads to a reduction in the cost due to the packaging and an increase in the storage capacities of the supplier and the user .

 The concentrated solutions according to the invention are suitable for numerous applications, in particular, the compositions prepared by steps (a) to (g) or by the variant indicated are useful as additives for building materials. They notably improve the fluidity and the compressive strength of mortars. From this. fact, all the applications using a mortar can be concerned with the present invention.

 The nonlimiting examples below are given to illustrate the process of the invention, as well as the properties of the materials produced using said solutions. In particular, a comparative study is given between the properties of a mortar treated with such solutions and those of an untreated mortar.

EXAMPLE 1
24 g (0.25 mole) of phenol, 17 g (0.25 mole) of a 44 percent by weight aqueous solution of formaldehyde and 100 g of water are heated with 1.8 g (0.0135 mole) ) 30% sodium hydroxide solution up to 800C and stirred for 10 minutes at this temperature.

24 g (0.126 mole) of sodium metabisulfite are then introduced and the mixture is heated for 60 minutes at the boil.

Then 17 g (0.25 mole) of a 44 percent by weight aqueous solution of formaldehyde and 2.6 g (0.0195 mole) of a 30 percent aqueous solution of sodium hydroxide are added. It is heated for another 1 hour at the boiling temperature. Then, cool to 8O0C, add 205 g (3 moles) of 44 percent by weight aqueous solution of formaldehyde, 126 g (1 mole) of melamine, 95 g (0.5 mole) of sodium metabisulfite and 1 , 3 g (0.01 mole) of a 30 percent by weight aqueous solution of sodium hydroxide, then heated to boiling until the sulfite is no longer detectable (about 2 hours). It is then cooled to 500C, concentrated sulfuric acid is added to pH 5 (3 to 5 g of concentrated acid is required). It is then kept for 2 hours at 500cl and then the pH is adjusted to 8.5 -9 by addition of a 30 percent by weight aqueous solution of sodium hydroxide and the mixture is heated to 90 ° C. for approximately 1 hour. After which it is cooled and the pH is adjusted to 10.5-11 with a 30 percent aqueous solution of sodium hydroxide. A product is obtained, slightly yellow in color, with a solid content of 56% by weight. This product, after dilution to 20% of solid matter, has a viscosity equal to 20 centipoise.

EXAMPLE 2
48 g (0.51 mole) of phenol, 35 g (0.5 mole) of a 44 percent by weight aqueous solution of formaldehyde and 130 g of water are heated with 3.4 g (0.025 mole) of a 30 percent by weight aqueous solution of sodium hydroxide up to 600C, and stirred for 30 minutes.

48 g (0.252 mol) of sodium metabisulfite are then added and the mixture is heated for 30 minutes at the boil.

Then 35 g (0.5 mole) of a 44 percent aqueous formaldehyde solution and 5 g (0.0375 mole) of 30 percent aqueous sodium hydroxide solution are introduced and the mixture is heated for another 1 hour. boiling. Then cooled to 800C, 205 g (3 moles) of aqueous solution containing 44 percent formaldehyde, 126 g (1 mole) of melamine, 95 g (0.5 mole) of sodium metabisulfite and 5 g (0, 0375 mol) of a 30 percent aqueous solution of sodium hydroxide, then heated to boiling until the sulfite is no longer detectable (about 90 minutes).

Then cooled to 500C, concentrated sulfuric acid is added to pH 5, then maintained for 2 hours at 500C, then the pH is adjusted to 9.5-10 by addition of an aqueous solution at 30 percent sodium hydroxide.

 Finally, a slightly brown product with a solid content of 55% is obtained.

EXEPLE 3
48 g (0.51 mole) of phenol, 35 g (0.50 mole) of a 44 percent aqueous solution of formaldehyde and 100 g of water are heated with 2.6 g (0.02 mole) of a 30 percent aqueous solution of sodium hydroxide up to 800C and stirred for 10 minutes at this temperature. 48 g (0.252 mol) of sodium metabisulfite are then introduced and the mixture is kept boiling for 30 minutes.

Then 240 g (3.52 moles) of 44 percent formaldehyde aqueous solution, 126 g (1 mole) of melamine and 5 g (0.0375 mole) of 30 percent aqueous solution of sodium hydroxide are added and it is maintained for 1 hour at the boil. Then 95 g (0.5 mole) of sodium metabisulfite, 5 g (0.0375 mole) of aqueous sodium hydroxide solution are added and the mixture is kept boiling until the sulfite either more detectable (about 2 hours).

 It is then cooled to 50 ° C., concentrated sulfuric acid is added to pH 5; it is maintained for two hours at 500C, then the pH is adjusted to 9.5-10 by addition of an aqueous solution of 48 percent sodium hydroxide.

 Finally, a slightly brown product with a solid content of 59% is obtained.

EXAMPLE 4
12 g (0.13 mole) of phenol, 9.5 g (0.14 mole) of a 44 percent by weight aqueous solution of formaldehyde, and 100 g of water are heated with 0.5 g (0, 00375 mole) of a 30 percent solution by weight of sodium hydroxide up to 800C and stirred for 10 minutes at this temperature. Then introduced 12 g (0.0631 mole) of
sodium meta bisulfite and heated for 30 minutes to the boil. Then added 9.5 g (0.14 mole) of a 44 percent aqueous formaldehyde solution and 0.5 g (0.00375 mole) of a 30 percent aqueous sodium hydroxide solution. The mixture is heated for another hour to boiling temperature, then cooled to 800C, 205 g (3 moles) of 44 percent formaldehyde aqueous solution, 126 g (1 mole) of melamine, 95 g ( 0.5 mole) sodium metabisulfite and 0.5 g (0.00375 mole) 30 percent aqueous solution of sodium hydroxide, then heat to boil until the sulfite is no longer detectable . It is then cooled to 500C, concentrated sulfuric acid is added up to pH 5. It is then kept for 2 hours at 500C and then the pH is adjusted to 9.5-10 by addition of an aqueous solution at 30 percent sodium hydroxide. The final product obtained is slightly yellow and has a solid content of 52 inches.

EXEIPLE 5
12 g (0.13 mole) of phenol, 8 g (0.12 mole) of a 44 percent by weight aqueous solution of formaldehyde and 100 g of water are heated with 0.4 g (0.003 mole) of a 30 percent by weight aqueous solution of sodium hydroxide up to 600C and stirred for 30 minutes at this temperature. Then introduced 11.5 g (0.06 mole) of sodium metabisulfite and heated for 30 minutes at 800C. 215 g (3.15 moles) of 44 percent formaldehyde aqueous solution, 128 g (1.02 mole) of melamine, 105 g (0.55 mole) of sodium metabisulfite and 0.2 g (0, 0) are then added. 0015 mole) of aqueous solution at 30 percent sodium hydroxide, then heated to boiling until the sulfite is no longer detectable. Then cooled to 500C, concentrated sulfuric acid is added until pH 5. Then maintained for 2 hours at 500C and then the pH is adjusted to 8.5-9 by addition of an aqueous solution of 30 percent sodium hydroxide and heated to 90 C for about 1 hour. After which it is cooled and the pH is adjusted to 10.5-11 with 30 percent aqueous sodium hydroxide solution. A slightly yellow product is finally obtained, with a solid content of 53%.

E-XAMPLE 6
Heated 16 g (0.17 mole) of phenol, 12.5 g (0.18 mole) of a 44 percent by weight aqueous solution of formaldehyde and 100 g of water with 0.65 g (0.005 mole) of a 30 percent by weight aqueous solution of sodium hydroxide up to 800C and stirred for 10 minutes at this temperature. 17.5 g (0.002 mole) of sodium metabisulfite are then introduced and the mixture is heated for 30 minutes at the boil. Then 11 g (0.16 mole) of a 44 percent aqueous formaldehyde solution and 0.5 g (0.00375 mole) of a 30 percent aqueous sodium hydroxide solution are added. The mixture is heated for a further 1 hour at boiling point, then cooled to 800C, 205 g (3 moles) of 44 percent formaldehyde aqueous solution, 126 g (1 mole) of melamine, 100 g (0.526) are added. mole) of sodium metabisulfite and 1 g (0.0075 mole) of 30 percent aqueous sodium hydroxide solution and then heated to boiling until the sulfite is no longer detectable. It is then cooled to 500C, concentrated sulfuric acid is added to pH 5. It is then maintained for approximately 1 hour at 500C and then the pH is adjusted to 9.5-10 with 30 percent aqueous solution of sodium hydroxide . A slightly yellow product is obtained with a solid content of 53%.

EXAMPLE 7
14 g (0.15 mole) of phenol, 9.5 g (0.14 mole) of a 44 percent by weight aqueous solution of formaldehyde and 100 g of water are heated with 0.5 g (0.00375 mol) of a 30 percent by weight aqueous solution of sodium hydroxide up to 800C and stirred for 10 minutes at this temperature. 13.5 g (0.07 mole) of sodium metabisulfite are then introduced and the mixture is kept boiling for 30 minutes and then 260 g (3.81 moles) of 44 percent formaldehyde aqueous solution are added; 150 g (1.19 mole of melamine and 1 g (0.0075 mole) of 30 percent aqueous sodium hydroxide solution and the mixture is kept boiling for 1 hour, then 123.5 g (0, 65 mole) of sodium metabisulfite, 1 g (0.0075 mole) of 30 percent aqueous sodium hydroxide solution and kept at boiling point until the sulfite is no longer detectable. 500C, concentrated sulfuric acid is added until pH 5, maintained for 2 hours at 500C, then the pH is adjusted to 9.5-10 by addition of a 30 percent aqueous solution of sodium hydroxide .

 A slightly yellow product with a solid content of 540% is obtained.

EXAMPLE 8 (application)
We prepare a normal mortar, according to the standard
NFP 15403, by mixing the following compounds
Compounds Parts by weight
Portland cement CPJ 45 450
Normal dry sand 1350
Water 225
a) Influence of the presence of an additive according to
the invention on fluidity for a report
E / C (Water / cement) constant and equal to 0.5.

Fluidity is measured by the collapse of a mortar cone under specified conditions. This test is a transposition at the mortar level of the "slump test" for concrete (NFP 18451). This test is also called
Abhrams cone test.

 To the mortar prepared beforehand, the dose, indicated in the table below, of a condensation product according to the invention is added, and the fluidity of the mortar obtained is measured.

Condensation product Dose in parts Fluidity according to the invention, added dry percent millimeters to mortar (DK 15 403) (at 100%) / cement
O (normal mortar) 0 15.7 according to example 1 0.3 29.3 according to example 3 0.3 26.6 b) Influenced by the addition of a conduction product
sation according to the invention on the compressive strengths of the mortar at constant W / C and
equal to 0.5.

 The CIM resin application standard was used. 4 (hydraulic binder mechanical tests, compression rupture tests). This test refers to standard NFP 15-451.

Principle of the CIN standard. 4
A 40 x 40 x 160 mm prismatic test piece in normal mortar, pure or modified with the additive under study, is tested in compression on the lateral molding faces, under a section of 40 x 40 mm, using '' a testing machine with a compression device
The value of the compressive breaking stress is determined on test specimens of 1 day of age.

Condensation product Dose in parts Test pieces according to the invention, 1% dry dry sweat for 1 day.

mortar tee (NFP 15405) (100%) / cement
break at
compression
R in bars
O (normal mortar) 0 90
Product according to example 1 0.3 145
Product according to example 3 0.3 130

Claims (8)

 1. Process for the preparation of stable concentrated aqueous solutions of anionic melamine / phenol / formaldehyde condensation products with sulfonic acid groups, having a solid content of at least 50 / s by weight, characterized by the following steps  a) heating to a temperature between 60 and 1000C, in the presence of a basic catalyst, an aqueous solution containing phenol, formaldehyde or a formaldehyde donor, and a metabisulfite in a molar ratio of 1 / 0.9- 1.1 / 0.45-0.55;  b) the condensation of the product obtained in (a) is continued, in the presence of a basic catalyst, with formaldehyde or a formaldehyde donor, at a temperature between 800C and the boiling temperature, using an amount of formaldehyde relative to the starting phenol, such that the formaldehyde / phenol molar ratio is in the range of 0.9 to 1.1;  c) then continues, in the presence of a basic catalyst, to condense at a temperature close to boiling with melamine, formaldehyde or a formaldehyde donor, and a metabisulfite in a molar ratio in the range of 1 , 9-8 / 5.8-24.8 / 0.9-4.4 based on the starting phenol, until the sulfite can no longer be detected;  d) the pH of the mixture is then adjusted using a concentrated mineral acid to a value between 4.5 and 5.5 and the condensation is continued for approximately 30 to 120 minutes at a temperature between 30 and 600C ;  e) the pH is then adjusted to approximately 8-10 using a concentrated aqueous solution of strong mineral base.  2. Method according to claim 1, characterized in that steps (b) and (c) are modified as follows  b ') the condensation of the product obtained in (a) is continued, in the presence of a basic catalyst, with melamine and formaldehyde or a formaldehyde donor, at a temperature between 800C and the boiling temperature , in a molar ratio in the range of 1.9-8 / 6.8-25.8 relative to the starting phenol;  c ') then continues, in the presence of a basic catalyst, to condense with a metabisulfite in a molar ratio of 0, C) to 4.4 relative to the starting phenol, at a temperature close to boiling, until there that the sulphite is no longer detectable.  3. Method according to claim 1 or 2, characterized in that it comprises the following additional step:  f) continuing to condense at a pH of about 8-10, at a temperature between 70 and 90 C, for a maximum of 60 minutes.  4. Method according to claim 3, characterized in that it comprises the following additional step  g) the pH is adjusted to approximately 10.5-11 using an aqueous solution of a strong mineral base.  5. Method according to claim 1 or 2, characterized in that, as basic catalyst, sodium hydroxide or potassium hydroxide at a rate of 1 to 20 mol% relative to the phenol.  6. Method according to claim 5, characterized in that the proportion of basic catalyst ranges from 1 to 10 moles / relative to the phenol.  7. Method according to claim 1, characterized in that, in step (c), the melamine / formaldehyde / metabisulfite molar ratio is within the range of 3.5-4.5 / 10-14 / 1.6 -2.5.  8. A stable concentrated aqueous solution of anionic melamine / phenol / formaldehyde with sulfonic acid groups having a solid content of at least 50% by weight, obtained by a process according to any one of claims 1 to 7 .  vs. Use, as an additive, to a building material such as a mortar, of a stable concentrated aqueous solution of a melamine / phenol / anionic condensation product with sulfonic acid groups, obtained by a process according to claim 2 or 4 .