DD209838A1 - METHOD FOR THE LARGE MANUFACTURE OF HIGH QUALITY DISPERSIBLE AGENTS - Google Patents

Abstract

The invention relates to the preparation of dispersants based on Naphthalinsulfosaeuren and formaldehyde. They are obtained by sulfonating naphthalene with sulfuric acid and reacting the sulfonating melt with formaldehyde in such a way that the water-added sulfonating melt adds the aqueous formaldehyde within one to two hours, then with closed reactor for two to six hours at 100 to 105 ° C. and then another two to six hours at 110 to 120 degrees C is condensed.

Description

242508 2

2181

Process for the large-scale production of high-quality dispersants \ ';. '.

Field of application of the invention

The invention relates to a process for the industrial production of high-quality dispersants based on naphthalenesulfonic acids and formaldehyde.

Characteristic of the known technical solutions

Condensation products of naphthalenesulfonic acid and formaldehyde are excellent for many applications © excellent dispersing agents-The nature of the suction guide in their production is of crucial importance for their quality.

DE-PS 1 137 005 describes processes for the preparation of condensation products of naphthalenesulfonic acids and aldehydes, in which the naphthalenesulfonic acid in a molar ratio 1 ί 0.2 to 2 is condensed with aldehydes at temperatures between 100 and 200 ⁰ O · The examples given are of a ß-Naphtha- linsulfosäure, which is formed by sulfonation of naphthalene with equal parts by weight of 98% H ₂ SO ^ at 160 ° 0 · The sulfonation mixture is then diluted with water, treated with aqueous formaldehyde and condensed at 120 ⁰ C. Compared to the process known from DE-PS 292 531, according to which the condensation in the temperature range between 60 and 100 ⁰ C is made, should

& 1982 * 029022

242508 2

2181

0.2 to 2 moles of aldehyde per mole of naphthalenesulphuric acid can be reacted faster at temperatures between 100 and 200 ° under elevated pressure. "

In large-scale batch operation, an empirically optimized process regime has prevailed, which provides high-quality dispersants in good reproducibility under these conditions. The comparative example identifies the most important details of the process which is considered as prior art practice

In the first stage, the sulfonation of naphthalene is carried out with equal parts 98% HgSO ^ at 160 ⁰ O-. After completion of the reaction, the Suifierungsgemisch is pressed into the condensation vessel, in which a certain amount of water was already · This must be such that the Naphthalinsulfosäureschmelze remains stirrable to about 80 ° 0 · At 90 ⁰ O, the aqueous formaldehyde solution run in 12 to 16 hours and condensed at 98.bis 100 ⁰ C until all the formaldehyde has reacted. This takes about 15 to 25 hours, so that a total of a residence time of an average of 40 hours results in Eondensiergefäß *

By fractional precipitation is detectable that the linearly condensed Naphthalinsulf © acids of the formula

SO ₃ Kia

SO ₃ Na

where n> 3 are mainly the carriers of the dispersing action. Of course, the regularity in the structure of the polycondensates is also important. The long-term condensation under relatively mild conditions therefore gives rise to particularly high-quality dispersants.

-O- 242 5 08 2

2181

The reaction conditions are matched to the concentration of H ₂ SO ₂ present during the condensation. "The condensation rate depends very much on the proton concentration, which has a catalytic effect. If, for example, the formaldehyde feed is shortened to half the time, increasingly three-dimensionally crosslinked, insoluble polycondensates are formed.

Object of the invention

The aim of the invention is a large-scale batch process for the production of high-quality dispersants from naphthalenesulfonic acids and formaldehyde, which results in qualitatively identical products in a shorter time and with less energy consumption compared to the current process with the same process stages.

Explanation of the essence of the invention

It has been found that the stated object can be reached in a surprising way, when the formaldehyde inlet is shortened to sulfonation mixture to a maximum of two hours and the condensation in the closed stirring apparatus at temperatures of 100 to 120 ⁰ C is carried out, "it has proven to be advantageous to connect to the accelerated formaldehyde feed a condensation phase of 2 to 6 hours at 100 to 105 ⁰ O and to follow a post-condensation phase of 2 to 6 hours at 110 to 120 ⁰ C. The postcondensation is complete when the formaldehyde, which can be analytically detected in the reaction-genomic, has fallen below 0.015 % of the amount used. In such an operating regime, it is possible to shorten the synthesis cycle compared to the previous method at least half the time and save considerable amounts of energy (heating energy, electrical energy) in qualitatively identical reaction products. ,

This result is surprising in that, according to the previous production experience and the current state of knowledge about

2181

the reaction mechanism of the acidic condensation of aromatics with formaldehyde, the rapid addition of formaldehyde to the mixing mixture leads one to expect an uncontrolled condensation, which leads to high proportions of three-dimensionally crosslinked resins or "to the gelation of the entire reaction mixture."

The condensation is initiated by the electrophilic substitution of naphthalenesulfonic acid (NSS) with formaldehyde (F) at the sites of highest density of lead:

ArH + OHoO 4 Ar - OH ^ OH II

OH ₂ OH

The hydroxymethyl compounds are very labile and readily protonatable in a strongly acidic medium, with intermediate forms of ammonium ions:

Ar-CH ₂ OH + H ^ ^ == Ar-OH ₂ O ₊ H ₂ O III

In the literature (eg OHQANIKUM, 7th ed. Berlin 1967, p. 313) it is assumed that the Oarboniumion reacts with still unsubstituted aromatics analogous to a FRIEDEIr-OlA-FTS alkylation to Diary lmethan- or »polyarylmethane compounds t ^;

Ar -OH ₂ ^^ + ArH - - ^ Ar-OH ₂ -Ar + H ^ IV

Thereafter, the kinetics of the di- or "polyarylmethane formation on the proton concentration, which engages in the reaction step III, and the current F-offer must be regulated"

The proton concentration is already largely determined by the upstream sulfonation of naphthalene "falls below a ^ Sp ^ excess of 0.25 moles per mole of naphthalene is no satisfactory Durchsulfierung more, since the reaction water dilutes the SuIfiersäure · The regulation of the F-feed to Suifiergemisch Therefore, it appears as the most important process variable for controlling the condensation process.

'' '' '2425OB 2

The empirical optimization of the synthesis of high - quality dispersants from NSS - F polycondensates has led to a time - related expansion of the F feed to 14 to 16 hours. If this time had been undershot, quality reductions in the final product and an increased accumulation of insoluble resin fractions were found in the industrial process »This phenomenon can be interpreted according to the reaction mechanism described by the possibility of multiple alkylation of the NSS component»

In-depth investigations of the condensation process have now shown that reaction step IV incorrectly describes the actual conditions. Rather, it is such that the carbonium ion reacts with aromatic carbon atoms already bearing a hydroxymethyl group

+ HO-CH ₂ -Ar ₂ ^ Ar ₁ -CH ₂ -Ar ₂ + CH ₂ OV

The methylene linkage is thus accompanied by the cleavage of F, which can substitute other NSS and thus open up a new reaction cycle. "The analytically detectable F in the reaction system is divided into the incoming primary F and the secondary F, which indicates the progress of the condensation. With this reaction mechanism, the surprising phenomenon that constitutes the subject of the invention becomes plausible. The substantially accelerated F feed to the melt is rapidly formed by methylol-substituted NSS. At the given proton concentration, a part of it is activated to the carbonium, while the rest participates as a passive reaction component at the condensation step V. When throttling the F-feed towards the previously practiced regime is apparently passed through a critical area in which it can lead to undesirable multiple alkylations of NSS, caused by the resinous by-products »This is justified by the previous ideas about the reaction mechanism is not a motive that the condensation on an industrial scale is being intensified by the rapid acceleration of the F feed.

-6-242 5 08 2

2181

fours "As the impact of such measures under laboratory conditions can be very imperfectly study, the direct transfer contained in the large-scale production a difficult kal · kulierbares economic Eisiko _β B, however, has proven beyond doubt that by the inventive method change controlled at all stages Seaktionskette proceeds according to the objective in significantly improved tree-time yield to linear IiSS-F - condensates or · polycondensates that have in comparison to the obtained by the previous method identical dispersing effect »

Embodiment .

In a stirring apparatus

1,680 kg (1.770 l) of naphthalene s'13.1 kmol presented, then heated to 150 ⁰ O and heated within two hours

1,680 kg (913 l) sulfuric acid 96% ig = 16.5 kMol

left ", the temperature rises to 160 to 165 ° C · The SuIfiergemisch stirred for two hours at 165 to 170 ⁰ O · after or until a poured into water sample; has only a slight turbidity (1 10).

The sulfide melt flows slowly over a heated line with stirring into a condensation vessel, in which 1 water are introduced. Bs imagines one

Temperature of about 85 ⁰ C on. Starting at this temperature, flow within two hours

kg (870 l) of formalin 30% ig = 9.5 kmol to, with the temperature on 94 · ⁰ O increases »With closed equipment then the reaction mixture stirred for six hours at 100 ^{0 0} and a further six hours at 110 ⁰ C after. After cooling the Naphthalinsulfosäure-formaldehyde condensate to 95 ⁰ G and aeration

-7-242 5 08 2

2181

of the agitator apparatus flow

1 * 120 1 of water too.

The aqueous condensate flows with stirring into the neutralization vessel, in which

2.100 1 of water are submitted »to the about 60 ⁰ C.

hot aqueous condensate acid are added in portions -

250kg chalk, ground, added · In this

Temperature flow

1,500 kg (985 1) of sodium hydroxide 50% = 18.8 kMol to, wherein

the temperature rises to about 90 ⁰ O increases. After adding

to 28 kg of sodium hexametaphosphate is the completeness ended neutralization with

kg of soda continued until pH = 7.2 to 7.6; possibly added water DgQ ₀ * 1,170.

At 90 ⁰ C, the gypsum precipitate is filtered off through a filter press and washed the gypsum cake with hot water.

Comparative example

Be in a stirrer apparatus

1,680 kg (1,770 l) of naphthalene = 13.1 kMol initially charged, then heated to 150 ° 0 and within two hours

1,680 kg (913 l) of sulfuric acid 96% strength = 16.5 kMol. to let. The temperature rises to 160 to 165 ° 0. The sulfonation mixture is stirred for two hours at 165 to 170 ⁰ C after or until a water-poured Erobe (1:10) has only a weak turbidity. The sulfonation melt flows slowly through a heated line with stirring into a condensation vessel, in which 1 water are introduced.

At 90 ⁰ O flow within 15 hours

- "- 242

2181

ig (870 1) formalin 30% "9.5 kMol too. After completion of Formalinzulauf the reaction mixture is stirred for a further 24 hours at 90 ⁰ O after «Then flow with stirring to 1,120 1 of water.

The aqueous condensate acid flows with stirring into the neutralization vessel, in which 2,100 1 wash water or "wash liquor are submitted"

After a portionwise addition of ig chalk, ground, flow within 10 hours. . . '''/ The -.:. -.'... '/ .. \ 1o500% (985 1) sodium hydroxide solution, 50% strength = 18.8 kmol (reaction mixture weakly acid to Congo red) to Following the addition of up to 28 kg of sodium. -heacametäphosphat with lig soda neutralization to pH = 7 »2 / to

7> 6 of the filtered solution continued; possibly: Iflasserzusatz 13 ^ q ₀ J 1 "17O In 70 to 80 ⁰ G gypsum precipitate is filtered through a filter press slowly and der.Gipskuchen out with hot water -.....,-.-." wash · ^-; · '7:.

The aqueous solution is spray dried to a gray powder.

Claims (1)

- ⁹ -242508 2 ²¹⁸¹ invention claim Process for the large-scale production of dispersants by dissolving naphthalene with sulfuric acid and reacting the sulfide melt with formaldehyde, characterized in that the water-added sulfonation melt in the condensation reaction or under stirring, the required amount of aqueous formaldehyde added within a period of one to two hours is then, with closed Keakfeor within two to six hours at 100 to 105 ⁰ C, the main condensation and then for two to six hours at 110 to 120 ⁰ O, the post-condensation takes place ·