CA1069519A

CA1069519A - Stabilization of polyalkoxylate nonionic surfactants

Info

Publication number: CA1069519A
Application number: CA239,262A
Authority: CA
Inventors: Robert B. Login
Original assignee: BASF Wyandotte Corp
Current assignee: BASF Corp
Priority date: 1974-11-07
Filing date: 1975-11-06
Publication date: 1980-01-08
Also published as: US4118326A

Abstract

Abstract of the Disclosure Liquid polyalkoxylate nonionic surfactant composi-tions are obtained that display improved stability when exposed to air at moderately elevated temperatures, such as 190 to 250°C. These compositions differ from those made and used in accordance with prior art in that they contain a significant and effective amount of ions of a metal, pref-erably an alkali metal such as potassium or sodium; and desirably, they do not contain anions of relatively non-volatile nature, such as phosphate, but rather, to the extent that anions are present, they are of volatile nature, such as acetate, propionate, butyrate, valerate or hexanoate. Such surfactant compositions of improved sta-bility can be made, for example, by conducting the poly-alkoxylation reaction in the presence of 0.6 weight percent of KOH and then neutralizing with acetic acid, or by adding an equivalent weight of potassium acetate to a completely deionized liquid polyalkoxylate nonionic surfactant composi-tion prepared according to the prior art.

Description

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Background of the Invention 1. Field of the Invention This invention relates to the making of polyalk-oxylate surfactant materials, and in particular, ~o the making of such materials for use in applications in which it is desirable that the composition exhibit substantial stability when exposed to air or oxygen at moderately ele-vated temperatures. In an aspect still more particular, the invention concerns the providing of such surfactant compositions for use in the spin finishing of textiles.

2. Description of the Prior Art Many polyalkoxylate nonionic surfactants are known.
They are made by starting with a material having one or more active hydrogen atoms such as an alcohol, phenol or amine, and then reacting it with several moles of at least one lower alkylene oxide, such as ethylene oxide or propylene ` oxide. Ethylene oxide units confer hydrophilic properties ; and propylene oxide units confer hydrophobic properties.
Those skilled in the art can often readily determine how to make a nonionic surfactant of desired properties, taking into account the relevant factors (starting material, desired physical form, desired hydrophilic-hydrophobic bal-ance, etc.). Many of the known composit:ions of this kind are liquidsJ rather than being gels, pastes, or solids ~ 5 ~ ~

(flakes or powders), and it is with the liquids that this in-vention is principally concerned.
In making liquid surfactants of this kind, it has been usual to use for the polyalkoxylation reaction a cata-lyst such as sodium hydroxide, potassium hydroxide, sodium ethylate, sodium methylate, potassium acetate, sodium acetate) or trimethylamine. It takes very little of ~he catalyst to get the desired effect. In most instances, 0.1 weight percent of potassium hydroxide will suffice.
After the polyalkoxylation reaction, it has been common, in making these liquid nonionic surfactants, to do one or the other of two things: (1) add acid to neutralize the catalys~, acetic acid or phosphoric acid being often used, or (2) mix the product with a very finely divided activated silicate material and then filter, to remove sub-stantially all ionic materials from the product. Alterna-tive (1) is usually adopted only when the product is too viscous to be filtered, a solid at room temperature, or the amount of catalyst used has been kept quite low. More often, alternative (2) is used. In either event, the liquid nonionic polyalkoxylate surfactant compositions made prior to this invention have had very little alkali-ion content or none at all. Moreover, it has not been suggested that there would ever be any reason to u8e more potassium hy-~a~

drt)x;de or ~he ]ike th~n the minimum necessary to catalyze the reac~ion~ or to take measures to obtain a final product containing any appreciable content of metal ions.
It has also been observed that the liquid sur-factant materials made according to practices outlined-above are not particularly stable when exposed to air at temperatures such as 190 to 250C. In cup tests (2 grams, exposed in a glass dish or aluminum cup to air for one hour at 220C., with weight taken before and after), many such liquid surfactant materials leave a residue of only 0.5 to weight percent, and though some others appear to have grea~er stability under such conditions (showing residue values such as 40 or 65~), they are nevertheless capable of ~ being improved. Under conditions even more stringent (one ; hour at 2~0C.), the untreated materials with which I have worked never left a residue of more than ~0%, and most of them did not leave as much as ?~ residue. Even under mild conditions (one hour at 190C.), only two materials out of eleven gave residue values as great as 60%.
It is also worthy of mention that polyalkoxylate nonionic surfactants of the paste or flake type, i.e., ones that are not liquid at room temperature, are not usually filtered, and they therefore naturally contain alkali-metal ions to at least the extent resulting from the use as a catalyst of an alkali-metal compound.

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Summar of the Invention Y
It has been foul~d that the stability of liquid polyalkoxylate nonionic surfactant compositions, when exposed to air at temperatures such as 190 to 250C., can be improved by ensuring that the composition contains an effec-tive proportion of metal ions, preferably alkali-metal ions such as potassium ions, preferably in compositions that con-tain only anions such as acetate that, as the corresponding acid, are relatively volatile at the temperatures involved.
Suitable compositions may be made by using during the poly-alkoxylation reaction a proportion of alkali-metal hy-droxide or salt somewhat greater than usual and omitting the often-practiced subsequent filtration of the product in ad-mixture with finely divided activated silicates. Preferably, if the product is neutralized, a lower saturated carboxylic acid such as acetic acid is used, rather than phosphoric, sulfuric, or hydrochloric acid. Alternatively, products made by the usual procedurej including the filtration in admixture with finely divided activated silicates, can be stabilized by adding to them an appropriate proportion of an appropriate hydroxide or salt, preferably an alkali-metal or alkaline-earth metal salt of a lower saturated carboxylic acid. Stabilized materials so made may be used in various ways, including their employment as spin-finish lubricants ~5~

in the production o~ man-made fibers, such as polyamides and polyesters .
Descri tion of the Preferred Embodiments p In accordance with the invention, a liquid poly-alkoxylate material, such as a nonionic surfactant material is made, substantially in accordance with practices hitherto known and ùsed, except for the differences particularly pointed out below. The differences relate to measures taken in order that the product may contain a proportion of metal ions that will be effective to promote the stability of the composition when it is exposed to air at temperatures such as 190 to 250C. The proportion of alkali-metal ions effec-tive for such purpose is commonly on the order of the equiv-alent of 0.2 to 2.0 weight percent of potassium as KOH. The composition preferably also does not contain anions such as phosphate which are poor bases and non-volatile as the con-jugate acid, but rather contains anions of lower saturated carboxylic acids,-such as acetic acid. Moreover~ salts of other suitably volatile acids may be used, such as the fol-lowing, it being understood that the following enumeration is to be taken as exemplary and not in a limiting sense, namely, formic, propionic, thioacetic, chloroacetic, di-chloroaceticJ bromoisobutyric, methoxyacetic, ethoxyacetic, butyric, valeric, caproic, oxalic, malonic, succlnic, chloro-~ 6 succinic, glutaric, benzoic, toluic, and lactic acids. Those skilled in the art will readiiy appreciate that salts of many other acids of similar chemical structure and characteristics may likewise be used.
In one manner of practicing the invention, there is used a proportion of alkali-metal hydroxide as catalyst for the polyalkoxylation reaction that is distinctly greater than usual. While it has been common to use as little of such catalyst as will accelerate the reaction satisfacto-rily, such as about O.l weight percent KOH or less, I flnd that for the purposes of this invention it is desirable to ~ ~9 5 ~ ~

use at least ~.2 weight percent of K~H and, depending upon the circumstances, possibly as much as 2 or ~ weight percent of KOH. Moreover, the often-practiced step of filtering in admixture with finely divided activated silicates to remove all ionic materials is eliminated, and to the extent that a neutralization of the material is desired or necessary, I
preferably add an acid having anions which as the conjugate acid are relatively volatile at temperatures such as 190 to 250C., such as acetic acid, or if desired, a different saturated carboxylic acid having up to about 18 carbon atoms. In this way, I may produce a liquid composition consisting principall~ of nonionic polyalkoxylate surfact-ant matter and containing a proportion of alkali-metal ions effective to promote the stability of the composition when exposed to air at a temperature between l90~C. and 250C.
In another manner of practicing the invention, a nonionic polyalkoxylate surfactant material is prepared exactly according to prior-art practices, including the filtration to remove ionic materials, but there is then added to the material an adequate quantity of a substance furnishing the desired proportion of metal ions. Commonly, this may be sodium acetate or potassium acetate, added to an extent such as 0.2 to 2 weight percent. It is usually desirable that the salt be added in the form of an aqueous

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solution. ~r most purposes, it is usually not necessary lo take meas~res to remove the wa~er added along with the salt.
Still another possible manner of practicing the invention is to use the alkali-metal acetate as catalyst for the polyalkoxylation reaction, and in so doing, to use more of it then is necessary or usual, such as 0.2 to 2.0 weight percent instead of the usual 0.05 to 0.15 weight percent, so that there will be obtained a product adequately provided with alkali-metal ions.
While not wishing to be bound by any particular theory, I theorize that in the matter of promoting the ther-mal stability of various polyalkoxy compositions, I have dis-covered that it is important that there be provided in the composition a quantity of metal ions, often but not neces-sarily ions of alkali metals, capable of tying up any car-boxylic acid groups developing by autoxidation in the poly-alkoxy composition when it is exposed to air at a service temperature such as 190 to 250C., thereby preventing un-wanted evolution of carbon dioxide and consequent degrada-tion of the polymer, which would otherwise occur in the presence of carboxylic acid groups. In a preferable manner of practicing the invention, the metal ions are supplied in the form of salts of relatively volatile acids, such as 10~ 9 acetic acid or other material that will volatilize when, act:in~ as a base, it neutralizes the above~mentioned car-boxylic acid groups and simultaneously forms the conjugate, volatile acid. This is contrary to the teachin~ of the prior art, in accordance with which the amount of potassium hydroxide used to prepare the oxide polymer would be kept as small as possible. Tests have revealed that although some material made in a laboratory on a small scale, wherein the usual filtration with the use of activated silicate was not practiced, would yield a material of adequ~te- stabil-ity, material made in accordance with the usual commercial practices, using the activated silicates, did not have the desired stability. It has thus been appreciated, in making of liquid polyalkoxylate nonionic surfactant compositions, that impurities of alkali-metal ions, such 8S sodium or preferably, potassium, of the kind that result from the use of sodium or potassium compounds as catalysts for the reaction of epoxyalkane with the starting amine or alcohol, have an important influence upon the stability of the final nonionic surfactant material obtained. This has never heretofore been appreciated. As mentioned ~bove, it has been usual to use as little of potassium hydroxide or sodium hydroxide as possible, to obtain the necessary cat-alytic effect, and then to remove or neutralize said _g_ .

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hydroxide. In accordance with the invention, however, there are thus obtained nonionic surfactant materials resulting from the reaction of amines or alcohols with epoxya]kanes that contain, in effect~ desirably larger portions of sodium ions or potassium ions, and preferably, a sufficient number of same to be effective to neutrali~e any carboxylate groups present in the materials formed by the vigorous oxidative conditions encountered in service at temperatures such as 1~0 to 250C., for example,during fiber processing at such temperatures. Although substantial benefits may in many instances be obtained with the use of relatively smaller proportions of material providing suitable potassium ions or the like, it is preferable, in accordance with the present invention, to provide on the order of 80 to 105 percent as many metal ions as are required in order to achieve, during a subsequent exposure of the nonionic surfactant composition to a service temperature on the order of 220C., sufficient of said ions to tie up any carboxylate groups present due to autoxidation.
The invention may be practiced with any polyalkoxy-late nonionic surfactant composition. Some compositions re- ;
quire a substantial addition of salt before there is much improvement. With others, remarkable improvement i8 some-times achieved by ~he addition of very little of the hy-droxide or salt. In some instances, using 0.2 weight per-cent of KOH as catalyst and neutralizing it with acetic acid will give a material with 20 times as much residue in a high-temperature cup test as the similar but deionized material produced according to the prior art. Experimen~al work has been conducted in respect to particular poly-alkoxylate nonionic surfactants of the kinds identified below:

Trade Mark or Name Nature Source Plurafacl Polyalkoxy- BASF Wyandotte lated straight- Corp., chain primary Wyandotte, alcohols Mich.

Pluradotl Heteric-polymer Do alkoxylated triols Pluronicl Difunctional Do block polymers containing EO
and PO units Tetronicl Polyether block Do polymers based on ethylene diamine Triton2 Polyethoxylated Rohm & Haas Co., t-octyl-phenol Philadelphia, Pa.

Igepal2 Polyethoxylated GAF Corp., nonyl-phenol New York ` Registered trademark of BASF Wyandotte Corporation, Wyandotte, Michigan, U.S.A.
2Registered trademark of indicated source company.

~95:19 As has been indicated above, it is considered that the active and effective entities that promote the stability of the surfactant composition are the ions of potassium, sodium or other metal present. The extent to which they are so effective is often importantly influenced by the anions present at the same time. A composition con-taining unneutralized KOH gives greater residues than one completely deionized, and a composition containing potassium phosphate is again superior to a deionized one, but results superior to those obtained with potassium phosphate are usually obtained with potassium acetate, a salt having an anion of a relatively volatile acid.
Polyalkoxylate materials stabilized against oxi-dation in accordance with the invention may be used in various ways that will be apparent to those skilled in the art. Stabilized polyalkoxylate materials in the nature of nonionic surfactants, may find use as spin-finish lubricants in the processing of textiles, or as dyeing assistants.
More generally, the invention is of use in any instance in which a liquid polyalkoxylate material is exposed in service to air or oxygen at a temperature such that the material, if not adequately stabilized, will degrade, and in which the addition of a metal compound in an amount effective to pro-vide adequate stabilization can be tolerated.

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As examples of the practice of this invention, compositions were made which consisted essentially of various polyalkoxylate surfactants plus different percent-ages of potassium acetate. These were subjected to cup tests, involving one-hour exposure of 2-gram samples in a circu-lating-air oven accurately maintained at the selected test temperature. For comparison, samples of the deionized surfactant itself were tested simultaneously. The results appear in the following Table I.

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In Table I, the Materials A to K are identified as follows.
A -- Polyoxyethylene derivative of t-octylphenol having an average of 9 to 10 EO units.
B -- Polyoxyethylene derivative of nonylphenol having an average of 9 EO units.
C -- Oxyethylated straight-chain primary alcohol having an average molecular weight of 770.
D -- Block copolymer of polyoxypropylene and poly-oxyethylene having a polyoxypropylene interior block, an average molecular weight of 4200, and about 40 weight percent of pol.yoxyethyl-ene units.
E -- Block copolymer of polyoxypropylene and poly-oxyethylene having a polyoxypropylene interi-or block, an average molecular weight of the polyoxypropylene hydrophobe of 950, and about 10 weight percent of polyoxyethylene units.
F -- Block copolymer similar to E but with average molecular weight of 1750 for polyoxypropylene hydrophobe and about 40 weight percent of polyoxyethylene units.
G -- Block copolymer of polyoxypropylene and poly-oxyethylene having a polyoxyethylene interior block, containing about 20 weight percent of ~)65~5i~

polyoxyethylene units and having an average molecular weight of 2500 for the polyoxy-propylene hydrophobe.
H -- Block copolymer similar to G, containing about 20 weight percent of polyoxyethylene units but having an average molecular weight of 3100 for the polyoxypropylene hydrophobe.
I -- Alkoxylated triols having an average molecular weight of 3900.
J -- Alkoxylated liquid triol having an average molecular weight of 4450.
K -- Block polymer based upon ethylene diamine and having polyoxypropylene units interior of polyoxyethylene units, the material having an average molecular weight of the polyoxypro-pylene hydrophobe of about 6750 and about 40 percent of polyoxyethylene units.
` The foregoing data reveal that the addition of 0.2 weight percent or more of potassium acetate fairly reliably increases the residue value, sometimes very remarkably with only a small addition (Materials A and I when tested at 250C. and Material E when tested at 190C. are good examples). The data reveal, moreover, that in many cases, better results are obtalned with relatively greater addi-tions of acetate, such as 1.0%.

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S~ill other tests were conducted.
Material E, deionized, had a residue in a similar test at 220C., of o.5 weight percent. With 0.2 weight per-cent of tripotassium phosphate added, the residue value was

4.4 weight percent. With 0.2 weight percent of potassium acetate, the residue value was ~ weight percent.
Material F, deionized, tested at 220C., gave a residue of ~.0 weight percent, but with 0.2 weight percent of tripotassium phosphate, the value was 15.0 percent, and with the same weight percentage of potassium acetate, the residue was 67 percent.
In a similar test at 220C., Materlal H had, when deionized, a residue value of 1.4 percent, versus 27 percent for the same material with 0.2 weight percent potassium acetate.
In a similar test at 220C., Material I, deionized, had a residue of 0.7 percent, but with 0.2 weight percent of potassium acetate added, the residue value was 42 percent.
Results of further tests are presented below in Table II. These were also cup tests at 220C., 1 hour, with samples of 2 grams.

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Additional tests were conducted with Material C.
Ap~roxima~e1y 20 grams thereof were divided into five por-tions of approximately 4 grams each. Potassium hydroxide (20 weight percent aqueous solution) was then added to four of the five portions, in amounts such as to give composi-tions containing 0.2, o.6, 1.2 and 2.0 weight percent of KOH. One portion was left untreated, as a control. All the portions were given an initial drying, by being heated at 110C. in a forced-air oven for ~0 minutes. The portions were then placed into glass dishes and tested by exposure at 220C. in a forced-air oven for one hour. The results were as indicated in Table III below. In each case, the residue was water-soluble.
TABLE III
KOH AddedpH ~ Residue 0 4.2 2~
0.2 4.4 67.6 o.6 4.9 ~o.6 1.2 7.6 92.1 2.0 10.6 96.4 Tests similar to those reported in Table III were conducted, again using Material C, but with 2-gram sample quantities, and with aluminum cups in place o glass dishes.
The results appear in Table IV below.

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TABLE IV
KOH Added pH % Residue O ND* 2.4 0.2 4.4 50.8 o.6 4.8 72.1 1.2 7 7 96.
*Not determi~ed -Tests similar to those reported in Table IV were condusted, but ~ith Materials D~ G, and H. The results appear in Table V below.
TABLE V
Material ~ KOH ~ Residue _ Added pH Observed D O ND* 2.5 D 0.2 5.051.2 D o.6 6.361.8 D 1.2 6.272.1 G O ND* 0.8 G 0.2 5.120.4 G o.6 5.648.8 G 1.2 6.452.9 H O ND* 2.8 H 0.2 5.240.9 H o.6 5.453.1 H 1.2 5-6 63.4 *Not determined Additional tests were conducted, using Material F
and hydroxides or salts of metals other than potassium. To be more specific, Material F was tested with calcium hy-droxide, lithium hydroxide, zinc acetate, calcium acetate, magnesium acetate, aluminum acetate and sodium acetate. The above-mentioned hydroxides and aluminum acetate were added neat to Mater al F; the others were added in the form of an aqueous solution containing 30 weight percent of the acetate.
The resul~s appear in Table VI below. The tests were done on 2-gram samples at 220C. for one hour. The reported values are averages of at least three determinations.
TABLE VI

Substance % % Residue Added Added Observed -None --- 1.1 Lithium hydroxide 0.2 12.9 Lithium hydroxide 0.5 20.1 Lithium hydroxide 1.0 21.5 Zinc acetate 0.2 2.8 Zinc acetate 0.5 4.2 Zinc acetate 1.0 4.9 None ___ O g Calcium acetate 0.2 14.6 Calcium acetate 0.5 27.2 (continued) 951~

TABLE VI (continued) Substance ~ ~ Residue Added Added Observed Calcium acetate 1.0 40.4 Sodium acetate 0.2 19.5 Sodium acetate 0.5 30-3 Sodium acetate 1.0 57-4 None Magnesium acetate 0.2 2.9 Magnesium acetate 0.5 4.9 Magnesium : acetate 1.0 14.0 None -- 1.0 Calclum :~
hydroxide 0.2 6.6 Calcium hydroxide 0.5 5.0 Calcium - hydroxide 1.0 6.2 Aluminum acetate 0.2 2.5 Aluminum acetate 0~5 4.0 Aluminum acetate 1.0 6.4 The foregoing results demonstrate that metals other than potassium will yield effective results, and that espe-cially favorable results can be obtained from the acetates of the alkali and alkaline-earth metals.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A Liquid polyalkoxylate nonionic surfactant composition having improved stability when exposed to air at a temperature of 190 to 250°C, which comprises alkali-metal ions to an extent equivalent to the use of 0.2 to 2.0 weight percent of potassium measured as KOH, and anions predominantly of a saturated carboxylic acid containing up to 18 carbon atoms.

2. A composition as defined in claim 1, wherein said anions are acetate.

3. A method of making a liquid polyalkoxylate nonionic surfactant composition having improved stability when exposed to air at a temperature of 190 to 250°C., which comprises reacting a starting compound having a reactive hydrogen atom with a lower 1,2-epoxyalkane in the presence of a proportion of alkali-metal-containing catalyst sufficient to leave in the product alkali-metal ions to an extent equivalent to the use of 0.2 to 2.0 weight percent of potassium measured as KOH, and neutralizing the reaction mixture by the addition of a saturated carboxylic acid containing up to 18 carbon atoms.

4. A method as defined in claim 3, wherein said carboxylic acid is acetic acid.

5. A method of making a liquid polyalkoxylate nonionic surfactant composition having improved stability when exposed to air at a temperature of 190 to 250°C., which comprises:
reacting a starting compound having a reactive hydrogen atom with a lower 1,2-epoxyalkane in the presence of alkali-metal containing catalyst, filtering the material so obtained in the presence of activated silicates to obtain a deionized material, and then adding to said deionized material a material containing a proportion of metal ions sufficient to leave in the product alkali-metal ions to an extent equivalent to the use of 0.2 to 2.0 weight percent of potassium measured as KOH, and anions predominantly of a saturated carboxylic acid containing up to 18 carbon atoms.

6. A method as defined in claim 5, wherein said anions are acetate.

7. A method as defined in claim 5, wherein potassium acetate in aqueous solution is added to a liquid polyalkoxylate nonionic surfactant solution.

8. A method as defined in claim 5, wherein said material containing metal ions is an aqueous solution of an acetate of a metal selected from the group consisting of the alkali metals and the alkaline-earth metals.