CA1218910A - Dispersing composition - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A composition of matter, useful as a dispersing agent, and method of making thereof. The composition comprises certain alkali metal salts of a condensation product of naphthalenesulfonic acid and formaldehyde.
The composition of matter is useful for pigment dispersions, emulsion polymeri-zation, leather tanning, water treatment, cement fluidization and many other applications. The composition remains stable when stored in liquid form at low temperatures.

Description

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~ACKGROU~ O~ T~I~ INy~NTION
~ his invention relates-to a novel dispersing agent composition.
This invention also relates tu a ~ethod ~or improving the properties of hydraulic cement-~a~ed mixtures ~ adding cer~ain alkali metal salts of a condensation product of naphthalenesulfonic acid and formaldehyde to the cement mixture, such as cement pas~e, mortar, concrete, and the like, Salts of condensation products of naphthalenesulfonic acid and formaldehyde are effective for the dispersion of cement particles and such cement dispersing agents are commercially available.
~he condensation product itself is generally prepared by sulfonating naphthalene with excess sulfuric acid and thereafter condensing the resulting naphthalenesulfonic acid with formaldehyde. ~he condensation product is then neutralized with an alkali metal hydroxide, eOg., sodium hydroxide, and the product is then treated to remove or reduce the water content. The commercial products, if not further processed, contain from about 5% to 22% by weight of sodium sulfate, on a dry basis. Sodiu~ sulfate is present because the excess su~furic acid employed in the sulfonation step is neutralized with sodium hydroxide. The sodium salt of the condensation products of naphthalene sulfonic acid and formaldehyde which are used as dispersing agents are frequently shipped, stored and added as liquid solutions. Sodium sulfate, the byproduct of the manufacture of the sodium salts of naphthalene sulfonic naphthalene-sulfonic acid and formaldehyde condensation products can precipitate as the decahydrate in cold weather, e.gO, below about 18C., depending on the concentr-ationO The result is that the sodium sulfate decahydrate crystals clog tanks, dispensers, etc~ and it is then impossible to properly handle the product.
The sodium sulfate salt can he eliminated ~y chilling and filtering ~2~89~ ~

or by neutxalizing w.ith calcium hydroxide and f~ltering. Richter, United States Patent 3,Q67,243 discloses a method of preparing ~alt free salts of naphthalene s-ulfonic acid~ormaldehyde condensates~O
Richter accomplishes the elimination of sodium sulfate b~ using an excess of naphthalene in the sulfonation step. This process, however, requires cl~5e monitoring throughout the reaction steps.
Johnson, United States Patent 3,277,162 discloses w:ater-soluble salts o the condensation products of naphthalenesulfonic acid and formaldehyde.
The cation of these salts may be sodium, potassium~ calcium, or ammonium ions. Johnson, however, does not address the problem of precipitation of s;odium sulfate decahydrate at low temperatures.
It is an object of this invention to prepare a dispersing agent which will not result in clogging tanks, dispensers, etc. when based on condensation products of naphthalenesulfonic acid and formaldehyde, stores or used at low temperatures, without having to remove sulfate salt byproducts.
It is another object to prepare a dispersing agent for cement which will give concrete proper~ies ~hich are equal to or better than those of concrete dispersed with conventional dispersing agents.
~t is a further object to prepare dispersing agents which remain stable when stored in the form of a liquid.
SUMMA~Y OF THE INVENTION
This invention involves a composition of matter useful as a dispersing agent and method of making thereof. The composition comprises a mixture of sodium and potassium salts of a condensation product of naph-thalenesulfonic acid and formaldehyde. The dispersing ag~ent is capable of being stored in the form of a liquid at low-temperaturesJ even though it 893L~

contains a significant amount of sulfatesO ~hen the composition is used as a dis-pers;ing agent or concrete, the propertles ~f concrete equal or exceed those o concrete prepared with conventlonal dispersing agents.
DETAILED ~E~C~IPTION

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This invention relates ko dispersing agents, and in paritcular, to aqueous solutions of dispersing agents wherein precipitates, crystals, or other solid particles ~hich are deleterious to dispensing equipment will not form at low temperatures. These dispersing agents are salts of conden-sation productsof naphthalenesulFonic acid and formaldehyde. As a byproduct of their formation, the dispersing agents con~ain sodium sulfate. At low temperatures crystals of sodium sulfate decahydrate will normally gather at the bottom o storage tanks and will clog dispensers and other equipment. By means of this invention, however, undesirable sulfate byproducts will not form precipitates or solids that will adversely affect dispersing equipment.
The condensation product of naphthalenesulfonic acid and formaldehyde which may be used in this invention can be prepared in such a manner as described below:
Naphthalenesulfonic acid is a well-known article of commerce.
There are numerous methods of preparing naphthalenesulfonic acid. One method involves stirring one mole of naphthalene with 1 to 1~5 moles of concentrated sulfuric acid, for example ~6% H2SO4, while heating to between 70C~ to 175Co It is well known that the temperatur~ of the reaction influences the ratio of 1 and 2-naphthalene~ulfonic acids in the end product.
At temperatures between 70Co and 90CO~ the naphthalenesulfonic acid comprises about ~0% of l-isomer and 10%!of 2-isomer. At 110C., about 75% o the 1-isomer is present and 25% of the 2-isomer; and at 140C., the product is about 25% ofl-naphthalenesulfonic acid and 75% of 2-naphthalenesulfonic acid. The 89~
ratio o~ the two lsomers in the naphthalenesulonic acid is in no way critical to this invention. Either lsomer or ~ixtu~es thereof can be used in this invention.
Formaldehyde, the other starting material used in this lnvention, is, o cours;e, a ~ell-known chemical compound, and it is generally available as a water solution, usually in a concentration of 30% to ~0~ by weight~
Such water solutions are preferred to produce the products of this invention.
However, other sources of formaldehyde are also within the scope of this invention. These include paraformaldehyde and trioxane. Para~ormaldehyde is a mixture of glycols having the fornul~ HO~CH20)nH where n varies from about 8 to 100. It dissolves in water with depolymerization and hydration to yield a solution of formaldehyde~ Trioxane in aqueous solution in the presence of a strong acid such as the sulfuric acid used for sulfonating naphthalene is also depolymerized to provide formaldehyde.
Naphthalenesulfonic acid and formaldehyde are condensed by heating at ~emperatures of about 60C to 13QC. About 0~5 to 3 moles of formaldehyde are used for each mole of naphthalenesulfonic acid. The conventional method of preparing the condensation product calls for adding sodium hydroxide after the reaction has reached the desired degree of condensation. According to 2Q this invention, however, a mixture of sodium hydroxide and potassium hydroxide is added to the aqueous solution of the condensation product of naphthalene-sulfonic acid and formaldehyde.
The s~dium hydroxide and the potassium hydroxide may be added separately or they may be blended and added together. Alternativelr, the sodium hydroxide and potassium hydroxide ma~ be added to separate batches of condensation products of naphthalenes;ulfonic acid and formaldehyde, and the thus, neutralized batches ma~ ~e b,lended ~n the des,ired ratio.
The mol~ ratlo o potassium hydroxide to sodium hydroxide may range from about 1 to about 3 mole$ potass,lum hydroxide to 1 mole sodium hy-droxide. The preferred mole ratio is about 2 ~oles potassium hydroxide to 1 mole sodium hydroxideO
The dispersing agent may be employed in either the form of de-hydrated powder or in the form of an aqueous solution. In the area of cement dispersion, it may be added to the cement in an amount of about 0.1 to about 10 percent, based on the amount of cement.
The dispersing agent composition may ~e either pre~mixed as the dried form with the hydraulic cement or added to concrete, mortar~ cement pas,te or the like at the time of mixing. It may be used alone, or in combination with other auxiliar~ agents su~h as a hardening accelerator, a retarder and an air entraining agent.
EXI`MPL~ 1 The condensation product of naphthalenesulfonic acid and formal-dehyde ~as prepared according to method ~hich is slightly modified from that disclosed in Tucker, United States Patent 2,141,569. The modified method is set forth belo~:
To 100 parts of concentrated sulfuric acid (specific gravity 1.84) contained in a suitable sulfonator and maintained at 160C~ are added slowly ~ith stirring 100 parts of refined naphthalene. After all of the naphthalene has been introduced (this operation generally requires about one hour~, the mass is stirred at 160Co for four hours longer or until a test shows that substantially none of the naphthalene remains unsulfonated. The sulfonation mixture is then cooled to about 100Cu and diluted with 44 parts of water to 9~L~

pre~ent sol~dif~cation on subsequent cooling. The diluted material is further coQled at 8QaC. at ~hich temperature 14.5 parts o a 40% aqueous solution of formaldehyde are added. This mixture is then stirred for three hours longer at 8QC.; but a~ the end of each successive hour there are added 14.5 parts ~ore of formaldehyde solution, making a total at the end of the three hours of four portions of 58 par~s in all. After all the formaldehyde has been added~ the temperature is progressively raised over a period of one hour to 95~100C. where it is maintained for 18 hours, while the mass is constantly stirred, or until a product of optimum effectiveness has been obtained.
Experience has shown that when pure naphthalene is used, a final heating period of 18 hours yields the best product. Soon after the temperature has been raised to 95-100C., it is found that substantially none of the aldehyde remains unconsumed in the condensation reaction. ~uring the later stages of the 18-hour heating period, ~he mixture progressively thickens until at the end it generally reaches the consistency of thick molasses. If this thickening becomes 50 great, however, as to prevent proper stirring a small quantit~ of water may be added to keep the material liquid. After the desired degree of condensation has been reached, the mixture is then cooled.
Portions of the resulting condensation product were then neutralized with the following alkali metal hydroxides:
A) sodium hydroxide B) sodium hydroxide; potassium hydroxide~ 1:1 mole ratio C~ sodium hydroxide: potassi-~ hydroxide~ 1:2 mole ratio D) sodium hydroxide: potassium hydroxide, 1:3 mole ratlo The alkali metal hydroxides were added at least until the naphthalenesulfonic acid-for~aldehyde product was neutralized.

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Each of the samples ~A~,(B),~C), and (D) was. frozen to 0F, and then ~a$ tha~ed gradually to 33~34Q~.
The following Table sets orth properties o:E the salts produced by the addition of the abovementioned alkall ~etal hydroxides:
TARL~ I
Sample Mole Ratio sod- ~olume of Con- Character of ium hydroxide:tainer Occupied Precipitate potassium hydroxide b~ Precipitate ~O) , . , _ A all sodium h~droxide 16 large, hard needlelike crystals B l:l 6 amorphous, fluid floc C 1:2 6 amorphous fluid floc V 1:3 32 amorphous, slightl~
fluid floc Although the amount of precipitate in Sample P was relatively high, the precipitate ~as amorphous and slightl~ fluid~ The dispersing agent formed ~ith this sodium hydroxide: potassium hydroxide mole ratio is suitable for conventional storage and dispensing equipment.
FXAPPL~ Il Six concrete mixtures, each of which contained 7690 g cement, 21,400 g 3/4.inch coarse aggregate, 17,650 g sand, and water as indicated 2Q in Table 2, were prepared. To t~he$e mixtures were added an air entraining agent ~PARAVAIR, manufactured b~ ~O R~ Grace ~ Co., Cambridge, Mass.) and the amounts and types of condensation product of naphthalenesulfonic acid and formaldehyde as indicated in Table 2.

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Slump tests, and compres,~ive s,trength..~ests ~ere conducted ~o~ each of the concrete sam~les. ~ercent air and weight per unit volume were also ~ecorded or each sample o-f concre~eO ~he results of ~he tests are set forth in Ta~le 3O
TA~E 3 Sample Slump Air Unit Compressive Strength ~Inches) ~%)Weight ~psi) 7 day 28 day ~ ~_ ~
B 2.25 506 141.9 1194 2844 3990 F 2.00 5.0 14308 2280 4058 4779 lQ G 1.50 5.0 143.5 2248 4073 4891 H 3.00 5~2 142O4 lOOQ 3248 3905 I 2. ao 4.5 145.1 1291 4260 498Q
J 2.25 4~5 145O1 1272 4053 4816 As clearly indicated in Table 3, the compositions employing the dispersing agen~ of the present invention, iOe~ Samples G and J, exhibit propert.ies ~hich are essentially equal to the properties of samples which contain a conventional dispersing agent, Samples F and I, and exceed those of untreated concretes, Samples E and Ho

Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A dispersing composition consisting essentially of a mixture of alkali metal salts of a condensation product of naphthlenesulfonic acid and formaldehyde.

2. The composition of claim 1 wherein the composition is in the form of an aqueous solution.

3. The composition of claim 1 wherein the alkali metal salts are sodium salts and potassium salts.

4. The composition of claim 3 wherein the molar ratio of sodium salts to potassium salts is from about 1:3 to about 1:1.

5. The composition of claim 4 wherein the molar ratio of sodium salts to potassium salts is about 1:2.

6. A method for preparing a dispersing agent which consists essen-tially of a mixture of salts of a condensation product of naphthalenesulfonic acid and formaldehyde which comprises the steps of:
(1) reacting sulfuric acid with naphthalene to obtain napthalene-sulfonic acid, (2) condensing said naphthalenesulfonic acid with formaldehyde, (3) neutralizing the resulting condensation product of naphthalene-sulphonic acid and formaldehyde with a neutralizing agent consisting of sodium hydroxide and potassium hydroxide.

7. The method of claim 6 wherein the sodium hydroxide is added prior to the addition of the potassium hydroxide.

8. The method of claim 6 wherein the potassium hydroxide is added prior to the addition of the sodium hydroxide.

9. The method of claim 6 wherein the sodium hydroxide and potassium hydroxide are added simultaneously.

10. The method of claim 6 wherein the sodium hydroxide is added to a first portion of the condensation product, the potassium hydroxide is added to a second portion of the condensation product and the first and second portions of the condensation product are combined.

11. The method of claim 6 wherein the molar ratio of sodium hydroxide to potassium hydroxide is about 1:3 to about 1:1.

12. The method of claim 11 wherein the molar ratio of sodium hydroxide to potassium hydroxide is about 1:2.