JPH06239950A - Condensation polymerization method - Google Patents

Abstract

PURPOSE: To obtain a sulfonated amine/aldehyde polymer useful as an superplasticizer in a cement-like composition through a specific method wherein an amine mainly comprising melamine, an aldehyde and a specific sulfonate group-providing substance are used.

CONSTITUTION: First, (A) an amine comprising at least 50 wt.% melamine is allowed to react with (B) an aldehyde (preferably formaldehyde) at an alkaline pH in the presence of (C) a substance which provides a sulfonate group to the final polymer, which comprises (i) sulfanilic acid and (ii) sulfamic acid and has a mol ratio of component (A) to component (i) of from 1:2 to 1.5:1, a mol ratio of component (A) to component (ii) of from 1.43:1 to 20:1 and a mol ratio of component (i) to component (ii) of from 1:0.05 to 1:0.7, to obtain a pre-condensate. Then, the pH of the pre-condensate is acidified by adding an acid (preferably formic acid) and subsequently, the obtained product is alkalized using a hydroxide of an alkaline metal to obtain the objective polymer.

COPYRIGHT: (C)1994,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing polymers, polymers produced thereby and cementitious compositions containing such polymers.

[0002]

BACKGROUND OF THE INVENTION Sulfonated amine-aldehyde polymers, especially where most or all of the amines are melamine, are
It is often used in cementitious compositions such as concrete. It is mainly used as what is called a "superplasticizer" and has the ability to reduce the water content of cementitious mixtures (often around 30%). Superplasticized concrete has a high degree of practicality, which allows for good flowability and easy placement, eg condensation is important when it comes with the inability to use complete formwork or vibration.

It is interesting to improve known sulfonated amine-aldehyde polymers, and typical examples of developments along this line are US Pat. Nos. 4,430,469 and 4,518,725 and European. Published Application No. 0001613
You can see in No. 5.

[0004]

DETAILED DESCRIPTION OF THE INVENTION Sulfonated amine-aldehyde polymers have been found according to the present invention which usually have low viscosities and therefore are easily incorporated into cementitious compositions and give them useful properties. Accordingly, a sulfonated amine provided by the present invention, wherein at least 50% by weight of the amine is melamine.
The method for producing an aldehyde polymer is as follows:
Producing a precondensate by reacting with H; (b) lowering the pH of the precondensate to an acidic pH by adding an acid; and (c) rendering the resulting product alkaline. ,
The substance capable of supplying sulfonic acid has both sulfanilic acid and sulfamic acid, the molar ratio of amine to sulfanilic acid is 1: 2-1.5: 1, and the molar ratio of amine to sulfamic acid is 1.4
It is 3: 1 to 20: 1, and the molar ratio of sulfanilic acid to sulfamic acid is 1: 0.05 to 1: 0.70.

The present invention further provides the sulfonated amine prepared by the above method. The present invention further provides cementitious compositions containing the above polymers. The present invention further provides the use of the sulfonated amine-aldehyde polymer produced by the above method as a superplasticizer in a cementitious composition.

The polymer is made from an amine and an aldehyde, the amine being at least 50% by weight melamine. More preferably, melamine comprises at least 90% by weight of amine, most preferably 100% by weight. Preferred aldehydes may include formaldehyde, and low concentrations (up to 10% by weight of aldehyde) of other aldehydes, preferably the aldehyde is 100% formaldehyde. Formaldehyde is usually (gaseous) form,
It can be used in solution form (formalin) or solid oligomerization form (paraform). Alternatively, it may be generated in situ.

The sulphonic acid groups (for the purposes of the present invention including those with sulphonic acid metal salts, especially alkali and alkaline earth metals, and most preferably sodium and potassium) are both sulfamic and sulphanilic acids. It is an important feature of the essence of the present invention. Some references suggest the use of both acids in the preparation of sulfonated amine-aldehyde polymers, but not the use of the two acids together in this way. It is not understood why this combination gives such good results.

The amount of the two acids used in the method of the present invention is 3
It is determined by two important parameters: the molar ratio of amine to sulfanilic acid and the molar ratio of amine to sulfamic acid and the molar ratio of sulfanilic acid to sulfamic acid. The molar ratio of amine to sulfanilic acid is from 1: 2 to 1.5: 1, preferably from 1: 1.25.
It is 1.2: 1, more preferably 1.1: 1 to 9:10 and most preferably 1: 1. The molar ratio of amine to sulfamic acid is 1.43: 1 to 20: 1, preferably 1.7: 1 to 9: 1, and more preferably 2: 1 to 5 :.
1 and most preferably 2.5: 1 to 4.3: 1.
The molar ratio of sulfanilic acid to sulfamic acid is 1:
0.05 to 1: 0.70, preferably 1: 0.09 to 1:
0.55, more preferably 1: 0.18 to 1: 0.3
6, most preferably 1: 0.2 to 1: 0.25.

The acids may be added separately or together to the initial mixture in which the precondensate has been formed. A typical method of the present invention adds sulfamic acid followed by sodium hydroxide and then sulfanilic acid to water. Amine and aldehyde are added to the mixture and maintained at elevated temperature for a period of time.

In the next step, the mixture is acidified by addition of acid. There are many acids that can be used for this, but preferably carboxylic acids, most preferably formic acid. In a preferred embodiment of the invention, alkali metal (preferably sodium) meta-bisulphonic acid is added at this stage. Although the manner of action of this substance is not understood, the polymers produced by the method used (particularly in combination with formic acid) have superior properties to those produced by the method not used. The mixture
5,000 to 30,000 daltons, preferably 7,50
0-20,000 Daltons and most preferably 10.0
Desired molecular weight distribution in the range of 0 to 15,000 daltons
The elevated temperature is maintained until it reaches (MWD), and this measurement is carried out by gel permeation chromatography using polystyrene sulfonate sodium salt as a standard. At this stage, the reaction is considered complete.

In the final step, the mixture is made alkaline with alkali metal hydroxide. Sodium tetraborate can be used to remove any remaining traces of formaldehyde. As mentioned above, the polymers of the present invention have a low viscosity which allows for easy bonding to cementitious mixtures. Generally, the cement content is 0.5 to 3%, preferably 1.5 to 2%. The composition has excellent flow properties. Further description is given in connection with the following examples of the invention, in which all parts are parts by weight.

Example 1 13.8 parts (0.142 mol) of sulfamic acid was mixed with 120 parts of water, and the pH was adjusted to 50% with a sodium hydroxide solution.
Adjust to 5. The temperature of the mixture rises to 40 ° C, 117
Parts (0.675 mol) of sulfanilic acid are added. The temperature was then raised to 55 ° C., with the desired 78 parts (0.618 mol) of melamine and 255 parts (2.088 mol) of 24.
Add 6% formaldehyde solution.

The temperature of the reaction mixture rose to 75 ° C.
Hold for 150 minutes, then add 150 parts of water and pour with formic acid.
Adjust H to 5.8. The temperature rises to 70 ° C and is maintained for 80 minutes. At the end of this period, 3.5 parts (0.009 mol) of sodium tetraborate decahydrate were added, maintaining the temperature at 70 ° C. and the pH was brought to 9.5 with sodium hydroxide solution. adjust. The temperature is kept at 70 ° C. for a further 30 minutes and the mixture is diluted with water to give a 31% by weight solids solution. The viscosity of the solution is 20 mPa.sec, measured at 20 [deg.] C. with a Haake "Rotovisco" NV device.

Example 2 6.9 parts (0.07 mol) of sulfamic acid are added with stirring to a reaction vessel containing 180 parts of water. Adjust the pH to 13.5 with sodium hydroxide (50% solution) and keep the temperature at 4
Raise to 0 ° C. and add 117 parts (0.675 mol) of sulfanilic acid.

The temperature rises to 55 ° C. and is continuously 84.9
Parts (0.673 mol) of melamine and 330 parts (2.70)
(Mol) 24.6% formaldehyde solution is added. The reaction mixture is heated to 75 ° C. and kept at this temperature for 45 minutes,
At that time 12.0 parts (0.06) diluted with 90 parts of water
(3 mol) of metabisulfonic acid was added, and the pH was adjusted to 5. with formic acid.
Adjust to 8.

The condensation reaction is carried out at 70 ° C. for 1 hour and 20 minutes.
3.5 parts (0.009 mol) of sodium tetraborate decahydrate are then added and the pH is adjusted to 9.5 with sodium hydroxide. After an additional 30 minutes at 70 ° C., the mixture is diluted with water to give a 31% by weight solids solution. Solution viscosity is 3 at 20 ℃
It is 0 mPa.sec (Hark Rotobisco NV).

Example 3 Comparative test on concrete The following concrete mixtures were produced: Portland cement 300 parts Sand (max 2.38 mm) 780 parts Coagulant (max 19.1 mm) 1155 parts. To make this dry mixture equal, (a) a sufficient amount of water to obtain a 220 mm initial crack.
(Italian Standard Test UNI9418), and (b) one of the following additives (i) commercially available β-naphthalene sulfonic acid aggregates (40 in water)
% Solids); (ii) commercial sulfonated melamine-formaldehyde aggregates (40% solids in water); (iii) solution of Example 1 (31% solids in water); (iv) commercial acrylic ester copolymerization. Combined (40% solids in water); (v) Commercially available esterified styrene-maleic anhydride copolymer (40% solids in water) was added.

The amounts added and the amounts in the compressive strength test (measured according to the Italian Standard test UNI 6132) are given in the table below:

Table 1 Additive Dose ¹ W / C ² Air ³ % Compressive strength (MPa) (20 ° C) 1 day 2 days 7 days 28 days (i) 1.0 0.51 2.0 14.1 22.9 30.2 44.0 (ii) 1.0 0.52 1.6 14.2 22.3 31.0 44.0 (iii) 1.0 0.52 0.8 16.7 24.5 34. 5 46.8 (iv) 0.5 0.56 561.1 2.1 11.9 19.1 29.8 41.2 (v) 0.5 0.53 9.3 12.7 19.6 28.5 39 .9

^One dose rate measures one liter of additive (solution) per square meter of cement. The dose of (iv) is low at high concentrations due to the overdue retarding effect. (v)
This is because in the case of, the air entrainment ratio becomes too high at a high concentration (this concentration is already too high). ² Water / cement ratio indicating the concentration required to obtain a single fracture. ³ Air dose in fresh cement, measured by Italian Standard Test UNI 6395.

The additives of the present invention entrain minimal air (high air entrainment reduces strength) and has both the most rapid strength development and the highest strength of 28 days.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ibana Torresan Italy 31100 Treviso, Via Pisa 15

Claims (4)

[Claims] 1. A precondensate is prepared by reacting an amine and an aldehyde at alkaline pH in the presence of (a) a substance capable of supplying sulfonic acid groups to the final polymer; (b) adding an acid. Thereby lowering the pH of the precondensate to acidic pH; and (c) rendering the resulting product alkaline;
The substance capable of supplying sulfonic acid has both sulfanilic acid and sulfamic acid, the molar ratio of amine to sulfanilic acid is 1: 2-1.5: 1, and the molar ratio of amine to sulfamic acid is 1.4
A sulphone in which the molar ratio of sulphanilic acid to sulphamic acid is 3: 1 to 20: 1 and is 1: 0.05 to 1: 0.70, wherein at least 50% by weight of the amine is melamine. For the preparation of a modified amine-aldehyde polymer. 2. A sulfonated amine-aldehyde polymer produced by the method of claim 1. 3. A cement-like composition comprising the polymer of claim 2. 4. A superplasticizer for cementitious compositions comprising the sulfonated amine-aldehyde polymer of claim 2.