WO1996016019A1

WO1996016019A1 - Biodegradable surfactant/emulsifiers

Info

Publication number: WO1996016019A1
Application number: PCT/US1995/014822
Authority: WO
Inventors: Vincent F. Smith, Jr.; Gary J. Gudac
Original assignee: Amoco Corporation
Priority date: 1994-11-23
Filing date: 1995-11-13
Publication date: 1996-05-30

Abstract

A water-soluble trimellitic acid-based biodegradable surfactant and emulsifier is disclosed for emulsification polymerization process. The water-soluble biodegradable surfactant and emulsifier is useful in emulsion polymerization processes for polymerizing monomers of styrene and vinyl chloride.

Description

BIODEGRADABLE SURFACTANT/EMULSIFIERS

Field of the Invention This invention relates to novel biodegradable water-soluble surfactants and emulsifiers for emulsification processes comprising mono-, di and triesters of trimellitic acid (1 ,2,4-benzene tricarboxylic acid). These biodegradable surfactants are useful as emulsifiers in the preparation of polymers. It has been found that, depending on whether the resulting surfactant is a mono-, di- or triester of trimellitic acid, the physical and chemical properties of the trimellitic acid surfactants are modifiable to be of nonionic, anionic or amphoteric type, have low to moderate foaming properties, and are individually soluble in water, xylene or 2-propanol. Water-oil interfacial tension values, i.e., water-mineral oil and water- heptane, of the novel surfactant/emulsifiers are comparable with commercial specialty surfactants and emulsifiers for emulsion and suspension polymerization processes.

Background of the Invention The surfactant art is quite old. Surfactants and detergents are among the most widely used products of the industry in the form of personal care and laundry soaps and emulsifiers. The introduction of synthetic surfactant products into the environment after personal, laundry and industrial use was a factor in increasing the presence of non-biodegradable compounds in streams and ground water. It was suspected that synthetic detergents were less readily degraded by microorganisms present in water and soil. Extensive investigation indicated that highly branched hydrophobic compounds containing a propylene oligomer group impeded the degradation of surfactants by microorganisms. These problems emphasized the need for biodegradable surfactants, that is, surfactants capable of being decomposed by bacteria or living organisms. The apparent remedy to the problem of biodegradabiiity was to replace the branched chain compounds with straight chain hydrocarbons.

U.S. Patents 3,382,285 and 3,956,401 teach nonionic surface active materials which are readily degraded by bacterial action. U.S. Patent 3,382,285 teaches a polyoxyalkylene material having a polyoxyalkylene chain of randomly distributed oxyethylene and oxypropylene units which are attached to an aliphatic straight chain derived from a monohydroxy primary alcohol. U.S. Patent 3,956,401 teaches a biodegradable liquid, non-gelling, nonionic surfactant comprising a linear alkyl hydrocarbon. It should be noted that these biodegradable surface active compounds are nonionic straight chain compounds. Nonionic surfactants do not ionize in solution and hence do not hold solid particulates in suspension in a washing solution, and are thus less effective than anionics in suspending soil and particulates.

Aromatic compounds containing a benzene ring were also found by investigators to be less biodegradable. However, aromatic compounds were found to be suitable as oil-soluble detergents and corrosion inhibiting fuel motor oil additives. U.S. Patent 4,404,001 teaches a detergent and corrosion inhibiting fuel additive as the product resulting from reaction of trimellitic anhydride and a C₁₀-C₂₅-hydrocarbyl-1 ,3-diaminopropaπe. U.S. Patent 3,951 ,977 teaches an oil soluble antirust, anti-wear, detergent- dispersant addition agent obtained by the reaction of a 4-acid halide of trimellitic anhydride with an alkyl-substituted phenol wherein the alkyl- substitient has 30 or more carbon atoms.

Despite the prior art indicating that aromatic compounds are unsuitable as biodegradable detergents and emulsifiers, it has been found that biodegradable water-soluble compounds can be prepared from 1 ,2,4- benzene tricarboxylic acid, (trimellitic acid) or trimellitic anhydride (TMA), and that these compounds are useful as nonionic, anionic, or amphoteric surfactants.

In emulsion polymerization, the emulsifier plays a key role, not only in the polymerization itself, but also in the finishing and properties of the latex as is taught in U.S. Patent 3,498,943 which teaches emulsification polymerization of vinyl polymers including styrene polymers and copolymers. It is important that the emulsifier be low in foaming, since this would eliminate the need for anti-foaming agents. It is important that the emulsifier be low in turbidity or haze since this is beneficial in ultimate use of the latex. It is important that the emulsifier be low in viscosity since this allows efficient transfer of the emulsifier without hold-up losses. It is also important that the emulsifier result in a low interfacial tension of the emulsified system comprising its polymer monomer, the activator and the other components of the emulsion system since this is beneficial to the process. It is important that the emulsifier demonstrate good hydrolytic stability since its emulsifier must stand up against deterioration in storage, transport, compounding and the like. The physical and chemical characteristics of the biodegradable surfactants of this invention which are nonionic, anionic and amphoteric surfactants indicate these compounds are useful in the emulsification of polystyrene, polyvinylchloride and other polymers depending upon the mono-, di-, and trisubstituted derivatives of trimellitic acid and alcohols, glycols, amines and metal salts thereof.

It is therefore an object of this invention to provide water-soluble compounds derived from trimellitic acid for water-oil environments.

It is an object of this invention to provide nonionic, anionic and amphoteric water-soluble surfactants and emulsifiers derived from trimellitic acid.

It is a further object of this invention to provide nonionic, anionic and amphoteric water-soluble surfactants and emulsifiers for emulsion polymerization of polystyrene, polyvinylchloride and other polymers.

Summary Of The Invention

This invention relates to novel biodegradable water-soluble surfactants and emulsifiers derived from trimellitic acid which are useful as surfactants for industrial and consumer use. These surfactants are particularly useful as emulsifier agents in emulsion polymerization processes for the preparation of polystyrene and polyvinylchloride, and other polymers. The surfactant compounds comprise mono-, di- and trisubstituted derivatives of trimellitic acid and alcohols of from 1 to 40 carbon atoms, glycols of from about 2 to 40 carbon atoms, hydroxy amines selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, propanolamine, dipropanolamine, tripropanolamine, and mono- and di-sodium and potassium salts of the acid anhydride group.

Details Of The Invention

The molecular structure of TMA includes anhydride functionality and free carboxylic acid functionality simultaneously on the same aromatic ring

This multiplicity of functionality makes possible the novel biodegradable surfactants. The structural feature common to all surfactant products is the co-existence of hydrophilic and hydrophobic regions within the same molecule. The distinctly differing reactivities of anhydride versus acid functionalities in TMA allow for the sequential, selective introduction of both hydrophilic and hydrophobic moieties into the same TMA-based molecule. The linkages which bind these moieties to the central aromatic are most commonly either ester or amide, depending on choice of reactants; in some cases the TMA portion of the molecule can itself serve as the hydrophile or hydrophobe. Consequently a huge variety of surfactant materials can be manufactured from TMA and very simple co- reactants including alcohols, alkylene oxides, amines, and thiols.

The versatility of the anhydride functionality and free carboxylic acid functionality of trimellitic anhydride and the concurrently available trimellitic acid allows the preparation of nonionic, anionic and amphoteric biodegradable water-soluble surfactants. Esterification of three acid moieties results in a nonionic surfactant. Esterification of the free carboxylic acid group and one of the acid moieties of the anhydride moiety can produce an anionic surfactant. Esterification of the free carboxylic acid group and reaction of one of the acid moieties of the anhydride moiety with triethanolamine results in an amphoteric surfactant although reaction with diethanolamine results in an anionic surfactant as do the metal salts of sodium and potassium. As is well-known, the utility of an emulsion is governed by ease of dilution, viscosity, color and stability. Surfactants with low foaming characteristics are preferred for laundry applications because of foam produced in waste water discharged to holding ponds and other receiving bodies of water such as lakes and rivers. Surfactants with low foaming characteristics are preferred for emulsion polymerization processes to preφare polymers of styrene and vinyl chloride. Ease of dilution of a surfactant can be determined by the relative viscosity of the surfactant compound after dilution. Emulsion polymerization is brought about by using monomer in the presence of an activator such as inorganic peroxy compounds, organic peroxy compounds, azo compounds and redox systems. Selection of the emulsifier will depend upon the properties of the emulsifier type, the other ingredients and the order of addition of ingredients during mixing to prepare the reactant mixture. There is, therefore, a continuing need for a class of surfactant compounds which can be prepared with different physical and chemical properties depending upon the intended application wherein the surfactants are biodegradable. For example, in emulsion polymerization, an electrolyte, e.g., aluminum sulphate, may be added to the emulsion to coagulate the polymer. As is well-known, nonionic surfactants are less susceptible to the action of electrolytes than anionic surfactants. The biodegradable water- soluble compounds of trimellitic acid, which can be nonionic, amphoteric and anionic, depending on substituent moieties, are suitable as aqueous phase surfactants for aqueous phase systems such as emulsion polymerization, textile scouring, hard surface cleansing, and metal cleaning. The biodegradable water-soluble surfactants of the instant invention are of the structure

wherein X is O or N, R is a liner alkyl hydrocarbon moiety of from 1 to about 40 carbon atoms, R' is a linear alkyl hydroxyl moiety of from 2 to about 40 carbon atoms, R' can also be a liner alkyl hydroxy amino moiety of from 2 to about 40 carbon atoms. R' and R" can also comprise hydrogen, sodium or potassium moieties. X is oxygen when — X — R' is a linear alkyl hydroxyl moiety of a dihydroxy compound such as a glycol. X is nitrogen when — X- -R' is a hydroxylamino moiety.

R' can be derived from linear alkyl dihydroxy compounds such as glycols and polyglycols including polyethylene glycols of from about 200 to about 2000 average molecular weight, as well as a hexahydric alcohol such as sorbitol.

R' and R" can also be the sodium or potassium salt of the anhydride group. R" can be an acidic hydrogen group.

Suitable alcohols from which R is derived include methyl, ethyl, n- propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-decyl, n-dodecyl, n- tetradecyl, n-hexadecyl, n-octadecyl and other alcohols up to about 40 carbon atoms.

Suitable monohydroxy compounds useful for the R' moiety are 2- ethylhexanol and n-decyl alcohol. Suitable polyhydric compounds useful for the R' moiety are polyethylene glycols including polyethylene glycol 400 and sorbitol.

Suitable hydroxylamines useful in the R' moiety as hydroxylamino groups are triethanolamine and diethanolamine. Other suitable hydroxylamines useful in the R' moiety are ethanolamine, propanolamine, dipropanolamine, tripropanolamine.

For a nonionic TMA-based surfactant, it is required that the three carboxylic acid groups of trimellitic acid be esterified. For an anionic TMA- based surfactant, it is required that R' be an alkyl hydroxy group and R" be hydrogen on the sodium or potassium salt. For an amphoteric TMA-based surfactant, it is required that R' be a hydroxylamine such as triethanolamine and R" is hydrogen.

The instant invention accordingly comprises a water-soluble TMA- based biodegradable surfactant and emulsifier of the structure

wherein X is O or N, R is a linear alkyl hydrocarbon moiety of from 1 to about 40 carbon atoms. R' is selected from the group consisting of linear alkyl hydroxyl moieties of from 2 to about 40 carbon atoms, hydroxylamino moieties of from 2 to about 9 carbon atoms, moieties of hydrogen, sodium and potassium, and R" is selected from the group consisting of linear alkyl hydroxyl moieties of from 2 to about 40 carbon atoms, and hydrogen, sodium and potassium. The water-soluble TMA-based biodegradable surfactants of this invention were evaluated as to physical properties and compared with commercially available typically representative surfactants and emulsifiers recommended by commercial producers for specific applications including emulsion polymerization processes with vinyl chloride and vinylidene chloride monomers. Physical properties were determined as indicated according to the described- procedures which follow.

Surfactant viscosity was measured using a Brookfield digital viscometer, Model DVI-LVTD. The viscometer was mounted securely to a Brookfield laboratory stand. Prior to operating the viscometer, the instrument was properly leveled using the bubble level located on the rear of the machine. The motor switch was turned "on" and the speed selector knob was set to 12 rpm. The viscometer was allowed to run until the display reading stabilized, and if necessary, was adjusted to zero with the zero adjustment knob. The motor switch was turned "off", placing the viscometer in standby mode. Spindle #2 was attached to the lower shaft (note left-hand thread). Spindle can be identified by the number inscribed on the side of the spindle nut.

Surfactant temperature was determined and the material was poured into a 4 inch tall, 120 ml (4 oz. ) glass jar. The spindle was inserted and centered in the test solution until the fluid level was at the immersion groove in the spindle's shaft. The speed selector was set to 12 rpm. The motor switch was turned "on" and time was allowed for the reading to stabilize. The digital reading was noted and multiplied by the factor appropriate for the viscometer model/spindle/speed combination. The viscosity is expressed in centipoise (m-Pa^»s). The factor was obtained from the Brookfield Factor Finder. When using viscometer Model DVI-LVTD, a factor of 25 was used for the 12 rpm speed.

Surfactant cloud point was determined following the procedure described in ASTM D2024-65. "Standard Test Method for Cloud Point of Nonionic Surfactants''. A 1.0% surfactant test solution was prepared by dissolving a 1 gram surfactant sample in 100 ml of room temperature distilled water. The mixture was agitated using a magnetic stir bar until all of the surfactant dissolved. Approximately 50 ml of test solution was then transferred into a 25 by 200-mrπ borosilicate test tube. While agitating the test solution slowly with a thermometer, the solution was heated in a 90° C water bath until it became definitely cloudy. The test tube was then removed from the water bath and allowed to cool slowly with gentle agitation until the solution became clear/transparent. The temperature associated with the transition from the distinctly cloudy to a clear solution was recorded as the cloud point.

Surface tension was measured according to the Wilhelmy Plate Method. Surface tension was measured using a Kruss digital thermometer, Model K 10 ST. Prior to operating the tensiometer, the instrument was properly leveled using the two front adjustment feet. The surfactant solution was stirred and transferred into the glass sample vessel. The vessel was then placed in the thermostat vessel chamber of the tensiometer. The eyelet of the sterilized platinum plate was then connected to the hook at the headpiece inside the instrument. The RUN-ZERO switch was set to the zero mode. The Ring-PLATE switch was set to the plate mode. The digital display was adjusted to 00.0 mN/m using the readout control knob on the top right side of the instrument headpiece. By means of the zero adjustment knob located on the left side of the headpiece, the balance beam of the force measuring unit was adjusted to its zero position. Position of the balance beam is displayed on the zero adjustment display on the front panel. The zero adjustment is set correctly when the pointer of the zero adjustment display indicates zero. The stop adjustment control was set to the zero position. The sample vessel was raised mechanically by activation of the vessel up switch until the lower edge of the plate was wetted by the test liquid. Following plate wetting, the motor for moving the thermostat vessel stops automatically and the vessel up knob was therefore released. The measurement is now completed automatically by the motor in the headpiece of the instrument. The plate was pulled out of the liquid until the lower edge of the plate was tangent to the liquid surface. The measured value was shown on the digital display. The measured values obtained with the plate method are absolute surface tensions and do not need to be corrected.

Interfacial tension was measured by the DuNouy Ring Method. Interfacial tension was measured using a Kruss digital tensiometer, Model K 10 ST. Prior to operating the tensiometer, the instrument was properly leveled using the two front adjustment feet. The phase with the lower density was transferred into the glass sample vessel and placed in the thermostat vessel chamber of the tensiometer. The eyelet of the sterilized platinum ring was then connected to the hook at the headpiece inside the instrument. The RUN-ZERO switch was set to the zero mode. The RING-PLATE switch was set to the ring mode. The ring was immersed approximately 3 mm below the surface of the lower density phase. The digital display was adjusted to 00.0 nM m using the readout control knob on the top right side of the instrument headpiece. By means of the zero adjustment knob located on the left side of the headpiece, the balance beam of the force measuring unit was adjusted to its zero position. Position of the balance beam is displayed on the zero adjustment. The light phase was removed and the sample vessel was cleaned. Also, the ring was removed and flamed with a propane burner. The glass sample vessel was then filled to the one-half mark with the heavier liquid. The sterilized ring was re-attached to the hook at the headpiece and immersed approximately 3 mm into the heavy phase. The heavy phase was overlaid very carefully with an equal volume of the light phase. Since the interfacial energy of a newly formed liquid-liquid interface generally requires some time to reach its equilibrium value, a 5 minute waiting period followed prior to making the measurement. Following the 5 minute waiting period, the RUN-ZERO switch was set to the run mode and the sample vessel was lowered using the sample elevation knob until the pointer of the zero adjustment display moved to a negative value. The servomotors start and the measurement is completed automatically. The measurement is completed when the pointer of the zero adjustment display moves to a positive value. The measured values obtained with the ring method have to be corrected, because in addition to the surface tension, the volume of liquid which is lifted by the ring is weighed as well. The correction factor (F) was calculated by use of the following equations:

F - 0.725 + 0.4036 x 10'³ — H- + 0.0128

IT = measured interfacial tension in mN/M D,d = densities of both phases in g/cm³

The Correction Factor was multiplied by 1.07 in order to calculate the Kruss correction value. The Kruss Correction Value was then multiplied by the measured interfacial tension value to obtain the final corrected interfacial tension of the system.

The Ross-Miles foam height test procedure was used to measure foaming properties. Surfactant foaming properties were determined following the procedure described in ASTM D 1173-53, "Standard Test Method for Foaming Properties of Surface-Active Agents." The equipment used in this test include: a specifically designed 200 ml glass pipet with a 60 mm iength lower stem and 2.9 mm inside diameter lower orifice, a 110 cm (total Iength) water jacketed glass foam receiver with a 50 ml, 250 ml, and 90 cm calibration mark, and a Neslab Exacel EX-110 constant temperature circulating bath. A 0.1% surfactant test solution was prepared by dissolving 0.30 gram surfactant in 300 ml of distilled water. The surfactant solution was heated on a hot plate at 49° C for a period of 30 minutes. While the surface- active solution was aging, water thermostatically maintained at 49° C was circulated through the water jacket of the foam receiver so as to bring it to the proper temperature. The walls of the receiver were rinsed with distilled water until the water drained down in an unbroken film.

At the completion of the aging period, the stopcock at the bottom of the receiver was closed. The walls of the receiver were then rinsed with 50 ml of the aged surface-active test solution. The pipet was filled to the 200 ml calibration mark and located near the top of the foam receiver. After securely mounting the pipet, the stopcock was opened. When all of the solution had run out of the pipet, a stop watch was started and an initial foam height was measured followed by a second measurement after a 5 minute time period. The reading was taken by measuring the foam production at the top of the foam column at the highest average height to which the rim of the foam had reached. The foam height has been determined to be proportional to the volume of air remaining in the foam. Foam height was reported as initial foam height (0 min.) and final foam height (5 min.)

The Draves wetting test procedure was used to determine wetting agent properties. Surfactant efficiency as wetting agents was determined following the procedure described in ASTM D 2281-68, "Standard Test Method for Evaluation of Wetting Agents by the Skein Test. Stock solutions were prepared containing surfactant concentration ranging from 0.1% to 1.0% with either pH 4 buffer, pH 10 buffer, or distilled water. The room temperature stock solution was transferred into a 500 ml graduated cylinder and the cylinder was placed on the platform of a ringstand equipped with an electric vibrator which was attached to the base of the apparatus in order to provide the vibrational energy necessary to liberate trapped air bubbles. The cylinder was allowed to stand on the vibrating surface for at least five minutes prior to testing. Residual foam on the surface of the solution was removed with an aspirator. A 3 gram copper S-hook attached by way of a 3/4 inch Iength linen thread to a 1 inch diameter lead anchor was fastaned to a 5 gram cotton skein with a lisle twist of 13 to 20 turns per inch. The cotton skein was drawn through a latex gloved hand using a twisting action in order to make it more compact. The skein was then held in one hand with the anchor suspended in the wetting solution contained in the 500 ml graduated cylinder and a stop watch was started just as the skein was released into the test solution. The watch was stopped when the buoyant skein began to sink to the bottom of the cylinder. The average of at least three determinations of sinking time for each concentration of wetting agent was obtained and recorded.

A hard surface wetting test procedure measured efficiency as a wetting agent for hard surfaces. Surfactant efficiency as hard surface wetting agents was determined using a ratio of the diameter of the surfactant solution spread droplet to that of the diameter of a spread droplet of water. Stock test solutions were prepared containing 1.0% surface active agent. The following test substrates were used: polyethylene, polystyrene, polycarbonate, pyrex glass, treated and untreated aluminum, and treated and untreated cold rolled steel. The testing procedure consisted of placing 0.02 ml of room temperature aqueous surfactant solution onto the various test substrates and measuring the droplet diameter after a 3 minute time period. The percent increase in diameter of a spread droplet over that of water alone was measured and recorded. A value of 300% diameter increase or greater is considered to be superior wetting.

The biodegradability testing procedure determined BOD and TOC. Two types of data were collected in order to evaluate the extent of biodegradation characterizing each of the products selected for testing. These data included Biochemical Oxygen Demand (BOD, %) and Total Organic Carbon reduction (% TOC reduction). BOD was measured by aerobic respirometry; based on the theoretical amount of oxygen required for complete oxidation of the surfactant to C0₂ and water. The actual oxygen uptake was continuously monitored and reported as a percentage of theoretical throughout the 360-400 hours of testing. The measurements were according to the test procedure published in "Standard Methods For The Examination of Water and Waste Watef 17th ed., Public Health Assoc. (1989). The TOC values on the other hand were measured by a combustion method, and only at the beginning and end of each test run. The results are reported as the difference between initial and final values, and expressed as a percentage of the initial level.

Surfactant samples were dissolved in water so that initial concentrations ranged from about 100 to 1100 mg/L, but were generally in the 200-300 mg/L range. At these latter concentrations, the corresponding initial dissolved organic carbon (TOC) levels were around 150 ± 50 mg/L. Activated sludge samples from a local sewage treatment plant were employed in all tests. Blanks which were surfactant-free were simultaneously run with all test specimens, and all runs were made at least twice, with the results averaged.

The following examples are exemplary only and are not to be construed as limiting the scope of this invention.

EXAMPLE 1

Among the reactions conducted with TMA, simple esterification is common. The first step in that process involves the facile opening of the anhydride functionality with an alcohol; the intermediate product is the mono-ester diacid which can then be reacted further under other conditions. Commercially, the diacid functionality can be ethoxylated with ethylene oxide; in the laboratory, esterification with polyethylene glycol) was conducted instead. The laboratory process for a nonionic surfactant is detailed below:

To a 150ml mini-flask equipped with a mechanical stirrer, cold water condenser, digital thermometer, and heating mantle was added 28.8g (0.150 mole) TMA flakes and 19.5g (0.150 mole) 2-ethylhexanol. After being blanketed with dry nitrogen, the mixture was stirred while heating to 160° C over the course of 2 hours. Throughout the heating period the mixture remained milky white and after cooling back to room temperature the mixture set up into a solid white cake. A sample of this caked product was dissolved in THF and analyzed by infrared; anhydride absorption (doublet, 1860 and 1780 cm^*1 remained. After reheating this intermediate product to a milky white fluid state, 120g (-0.3 mole) polyethylene glycol (PEG, MW 400, Aldrich) along with 28mg FASCAT 4101 (butylchlorotin dihydroxide, Elf Atochem) was added. After stirring and heating to 140° C for 30 minutes, this mixture became transparent and homogenous with a light yellow tint. The apparatus was modified so as to accommodate a distillation head for water removal and the temperature of the mixture was increased to 195- 205°C under a slight positive flow of nitrogen. After one hour, a sample was withdrawn and the acid number determined; a value of 71 mg KOH/gram sample was measured (non-esterification of the added PEG would yield an acid number of 100). After an additional four hours, the acid number had dropped to 42, and 0.8ml distillate had collected; 10 hours at about 200° C yielded a final acid number of 5mg KOH/gram and 1.9ml distillate. This octyldi-PEG trimellitate was evaluated without further purification. Although three different sites for esterification of TMA are available, if only one or two of these sites are reacted, the remaining site(s) can be converted to the carboxylate salt. Because of these multiple sites of reactivity, judicious selection of co-reactants can provide a range of molecular structures and properties which can be tailored to the requirements of a particular surfactant application. Two different methods for making TMA-based products of the anionic type are detailed below; one to prepare a targeted acid number; one to prepare an anhydride ester intermediate.

EXAMPLE 2

A product with a targeted acid number was made as follows: To a 500ml 3- necked round bottom flask equipped with mechanical stirrer, water cooled condenser, digital thermometer, and heating mantle was added 57.6mg (0.365 mole, Vista Chemical) n-decanol; then the system was blanketed with dry nitrogen and heated to 170° C. Over a period of 20 minutes, 70. Og (.365 mole) of flaked TMA was added to the stirred mixture. After three hours at 170-180°C, the milky white mixture was treated with 146g (0.365 mole) PEG-400 and the mixture became transparent and homogenous. The temperature of the mixture was increased to 200° C over the next 31/2 hours while 7ml of a two-phase distillate was condensed from the overhead vapors. An acid number of 83mg KOH/gram was measured for this product (the diester derivative from these materials has a theoretical AN of 77). This acid number is consistent with the structure of decyl mono-PEG trimellitate. This method of synthesis is not be expected to yield any of the isomeric products in particularly pure form. The method which follows would better provide such a product.

EXAMPLE 3 A product with an anhydride ester intermediate was made as follows: According to this procedure, the initial reaction of TMA with an appropriate alcohol is conducted in two stages, in the first stage a monoester diacid is formed; then in the second stage, this product is thermally converted to a monoester anhydride intermediate which can then be used to produce a variety of finished surfactant materials via anhydride ring opening. The following process details are typical of the first stage preparation. To a 1000ml 3-necked round-bottomed flask equipped with a mechanical stirrer, digital thermometer, and condenser/Barrett trap, was added 190g (1.20 mole, Vista Chemical) n-decanol. After being swept with dry nitrogen, the flask and contents were initially heated with a mantle up to 75°C. After about 150g (0.78 mole) TMA had been added with stirring and the temperature had been raised to 170°C, the mixture became transparent. The remaining 80g of TMA (1.20 mole total) required heating to about 230°C before the reaction mixture again became transparent. Continued heating at 245-270° C with a nitrogen sweep for a period of 2 hours resulted in the collection of 22ml of condensate (two layers, 5ml upper and 17ml lower) in the trap. Since the theoretical amount of water alone produced from this process would be 22ml, an additional 5g (.095 mole) n-decanol was added to the mixture before heating for an additional 2 hours. This resulted in the collection of a small additional amount of condensate (1 ml each layer). Upon cooling to room temperature, the product became a waxy, off-white solid. Acid number measurements and infrared spectra were consistent with the structure of the 4-decyl ester of trimellitic anhydride. The following process using PEG-400 (polyethylene glycol, MW 400) is typical of the second stage preparation. To a 150ml mini-flask equipped with a mechanical stirrer, cold water condenser, and digital thermometer, was added 66. g (-0.2 mole) 4-decyl trimellitate anhydride and 80g (-0.2 mole, Union Carbide, Carbowax) polyethylene glycol, PEG-400. After being blanketed with nitrogen, the mixture was heated with stirring to about 80°C, at which point the mixture became homogenous. An IR sample showed anhydride largely unreacted; after heating at 110-130°C for only 1 hour, the anhydride absorption had nearly disappeared. The resulting light yellow, slightly opaque liquid had an acid number of 91 which was somewhat higher than the theoretical value of 77. This product was evaluated without further treatment.

The above procedures were used to produce surfactants included in Table 1 , i.e., with polyethylene glycol, sorbitol, triethanolamine, diethanolamine, and aqueous KOH. IΔBLE.

Surfactant Products Evaluated

Surfai tfant Chemical Comoosition

Code R ff R"

AAA 2-ethylhexyl PEG-400 PEG-400

BB n-decyl PEG-400 H

CC n-decyl sorbitol H

DD n-decyl TEA H

EE n-decyl DEA H

F n-decyl Na Na

NOTE: TEA - Triethanolamine

DEA - Diethanolamine

EXAMPLE 4

The surfactants listed in Table I were tested and compared with commercially available surfactants of the following descriptions:

Commercial Description

ComA sodium dialkyl sulfosuccinate ComB disodium alkyl sulfosuccinate Com C polyether modified dimethyipolysiloxane Com D fluoroaliphatic polymeric ester ComE EO/PO copolymer ComF ethoxylated tetramethyl decynediol The following properties were determined by the procedures already described:

• Viscosity

• Cloud point

• Surface tension reduction

• Interfacial tension reduction

• Ross-Miles Foam Height (ASTM D 1173-53)

• Draves Wetting (ASTM D 2281 )

• Hard-surface Wetting

• Biodegradation

The resulting data are summarized in Tables II, III, IV, V, VI, VII and VIII. The physical properties collected in Table II show that the TMA-based products range from pale yellow thick liquids to high melting white powders. All are water soluble with varying degrees of haze, and some are organic soluble as well. Both physical form and solubility behavior are dependent more on co-reactant structure than on the incorporation of TMA into the formulation. Requirements of form or solubility can therefore be satisfied by proper adjustment of reactive formulations.

TABLE II Physical Properties of TMA-Based Surfactant Candidates

Surfactant Melt/Pour Yi≤fiaaϋi. Cloud point. SolubilitγC (3)0.5% Code Form Tvpa ^point- *C CP5.25°C 1 Mln. ^,C

Water Xylene 2-orooanol

AAA pale yellow nonionic -21 1648 53 s s H liquid BB paiβ yellow anionic -18 1360 b H s S liquid OC off-white anionic 42 1910« - H D S waxy semi-solid

DO pale orange amphoteric 48 4800» - H s I waxy semi- solid

EE light yellow anionic 45 5360» H s I waxy semi- solid

F white powder anionic >300 a Viscosity determined at 100° C. b Slightly cloudy at 0° C. c S - Soluble, clear, though it may possibly have a trace of haziness or undissorved matenal. H • Soluble with haze, hazy, turbid, or opalescent in appearance but no gross separation. D - Insoluble, self-dispersing or sell-emulsifying; on standing, separates into distinct phases; on shaking, may be dear, translucent or milky. I • Insoluble; gross separation into distinct phases which separate rapidly on standing after shaking. Surface tension effects are summarized in Table III. These data indicate that nonionic products derived from TMA and polyethylene glycols (Code AAA) give maximum surface tension reductions (32.9 dyne/cm) quite similar to those in the middle of the range (21.8-42.5 dyne/cm) for the commercial nonionics included. The anionic TMA-based product (Code F) gives a value 24.1 dyne/cm) which is lower than the commercial anionics. The other TMA- based products give generally intermediate values which average around 32 ± 2 dyne/cm. The limited data collected at surfactant levels below 1% indicate that the efficiency of the TMA-based nonionic product (AAA) is exceptionally high, giving 96% of the maximum surface tension reduction measured at 1%. The data demonstrate that the other TMA-based products as well as the commercial samples give low reductions at low concentration.

TABLE III

Aqueous Solution Surface Tension Values

Surface Tension, dyne/cm @

Surfactant Code 1% 0.1 % 0 , 01 % none 72.0 - -

AAA 32.9 33 34.4

BB 32.5 37.1 42.6

CC 29.9 - -

DD 31 .9 - -

EE 33.7 - -

F 24.1 28.4 42.6

Com A 26.0 - -

Com B 25.1 28.0 45.1

Com C 21 .8 232 24.1

Com D 27.0 - -

Com E 42.5 - -

Com F 28.4 36.1 — Interfacial tension effects are found in Table IV. Among all of the tested materials, three of the TMA-based products and two of the commercial products display better performance. The sorbitol product (Code CC) shows a large effect at both the water-mineral oil and the water-heptane interface. The anionic double salt (Code F) displays a large effect in only the water-mineral oil system, and the half-ester with PEG (Code BB) shows a strong effect in the water-heptane system. Commercial sulfosuccinate products (Com A and Com B) give good performance in both water-organic systems and have been recommended by commercial producers for emulsion and suspension processes with vinyl chloride and vinylidene chloride monomers. Effective reduction of interfacial tensions are considered to correlate with performance in emulsion polymerization systems indicating Code BB, Code CC and Code F are equivalent to commercial emulsifiers used in emulsification polymerization processes with vinyl chloride and vinylidene chloride monomers.

TABLE IV

Interfacial Tension Values

Water-Oil Interfacial Tension^* (dyne/cm)

Samole Code Water-Mineral OH Water-Heotane

None 35.7 48.2

AAA 3.7 4.4

BB 3.7 1.7

CC 1.7 1.5

DD 4.6 5.5

EE 4.6 3.2

F 1.9 8.0

Com A 1.9 1.5

Com B 1.6 1.0

Com E 14.9 12.5

Com F 4.7 3.6

Values determined on 1% solution at room temperature using DuNouy ring method. Ross-Miles foam heights are included in Table V. In general, the TMA-based products give moderate to low foam with heights in the range of 20-60 mm; the TMA-sorbitol product (Code CC) gave the least foam with initial and final heights of 9 and 3 mm. The commercial products vary from 203 mm (Com A, dialkyi sulfosuccinates) to zero or near zero (Com C, modified polysiloxane, or Com F, ethoxylated decynediol). Although the desired foaming behavior is dependent upon the particular application, most of the applications for these products will be in the industrial area and will benefit from a low foam characteristic which is taught in the prior art as a key element in emulsion polymerization of styrene polymers and copolymers.

TABLE V Ross Miles^* Foam Height Values

Measured Foam Height, mm

Surfactant Code Initial After 5 minutes

AAA 27 20

BB 51 42

CC 9 3

DO 22 21

EE 15 13

F 60 53

Com A 203 140

Com B 46 29

Com C 0 0

Com D 14 9

Com E 24 5

Co F 5 0

* ASTM D 1173-53, 0.1% aqueous surfactant solution; foam generation determined at 49°C. Draves wetting times given in Table VI indicate that these particular TMA- based products are typically comparable in the aqueous wetting of cotton to Com E of the commercial products under these test conditions.

TABLE VI

Draves^* Cotton Wettinα Values

Surfactant Code. Wettinq Times, sees

AAA 44

BB 214

CC >600^b

DD >600^b

EE >600^b

F 133

Co A OC

Com B 12

Com C 29

Com D 35

Com E >600

Com F OC

a ASTM D 2281 , 0.5% surfactant unless otherwise noted b Solution at 0.5% was too hazy to allow measurement; adjusted level to 0.1% c Value at 0.1 % was 288 sees for Com F, but stilt zero for Com A.

The hard surface wetting data collected in Table VII show that the starting point formulations for the TMA-based products in this study are moderately effective as surface wetting/flow agents and approximately equivalent to the results obtained from commercial products or Com D and Com E. The TMA- based products give less than 150% drop-spreads, while the commercial products generally give values in excess of 200-300%. Com D and Com E of the commercial references give values of 75% or less. It is considered that these test data correlate with coating application performance.

TABLE Yll

Hard Surface Wettinα Results

Surfactant % Increase in Soot Diameter. Substrate

Code E£ -ES EC OtaBR Δl Steel

AAA 53 88 94 64 65 132

BB 72 75 113 68 90 141

CC 73 100 88 59 70 73

DD 38 81 69 18 45 64

EE 44 75 100 32 45 141

F 56 63 94 136 45 64

Com A 200 194 175 1 18 160 218

Com B 175 >300 288 209 100 >300

Com C - 219 - - 100 -

Com D 75 69 75 27 40 59

Com E 31 31 25 9 0 18

Com F 94 250 181 127 125 218

ϋttlft:

PE polyethylene

PS polystyrene

PC polycarbonate

AL aluminum The biodegradation data collected in Table VIII demonstrate that the TMA- based surfactant candidates show good biodegradability. It is noted that those products which retain either carboxylic or sulfonic acid functionality display a tendency toward complete biodecomposition as measured by total organic carbon reduction (TOC %). It is considered significant that all of the TMA ester-based nonionics show distinctly greater biodegradability than the aliphatic ether-based product (Com F).

TABLE VIII

Biodegradability Testing Results^*

ΔΔΔ ΛAA-X βfi E Com A Com

Biochemical oxygen Demand. %h

100 hr. 17 29 20 9 36 6 200 hr. 28 40 50 - 56 12 300 hr. 32 48 64 - 61 ^c 14^c 400 hr. 32*- 49*- 67 _ _ _

Modified OECD Screening, % TOC reduction end of test 48 44 87 76 77» 10*

a All data except those noted were determined in at least duplicate and averaged b Determined by Aerobic Respirometry; reported as % - [(0₂ uptake s m le

-0₂ uptake _b|_ank) + 0₂ uptake _thβ0fy] X 100 c Total organic carbon (dissolved) analyzed by combustion method. d 350 hours e 250 hours (simultaneous test with surfactant candidate #BB gave 94% TOC reduction) f 150 hours EXAMPLE 5

Storage stability of a TMA-based biodegradable surfactant was determined by measuring surface tension of a sample stored over a period of 23 days at a temperature of 49° C. The pH of the solution was 10. The TMA- based biodegradable surfactant chemical composition (Code F) was as follows: R was n-decyl. R' and R" were the sodium salts. The commercial surfactant was the disodium alkyl sulfosuccinate (Com B). Concentration in a water solution of each surfactant was 0.02 wt.%. Measurement of surface tension was by the Wilhelmy Plate Method in dynes/cm. Results were as follows:

TABLE IX

Hvdrolvtic Stability of Surfactants

Surface Tension-Dynes/cm

Days Code F Com B

0 26.1 25.0

1 26.1 27.0

3 26.1 28.2

7 25.8 28.6

13 24.3 29.0

23 23.7 32.0

Surface tension of Sample Code F decreased with time, indicating greater stability as compared with commercial sample, Com B, the surface tension of which increased with time.

Claims

That which is claimed is:

1. A water-soluble TMA-based biodegradable surfactant and emulsifier compound for an emulsification process, the compound of the structure

wherein X is O or N, R is a linear alkyl hydrocarbon moiety of from 1 to about 40 carbon atoms, R' is selected from the group consisting of linear alkyl hydroxyl moieties of from 2 to about 40 carbon atoms, hydroxylamino moieties of from 2 to about 9 carbon atoms, moieties of hydrogen, sodium and potassium and R" is selected from the group consisting of linear alkyl hydroxyl moieties of from 2 to about 40 carbon atoms, and moieties of hydrogen, sodium and potassium.

2. The compound of Claim 1 wherein X is O, R is a 2-ethylhexyl moiety, R" is polyethylene glycol 400, R" is polyethylene glycol 400 and the compound is a nonionic surfactant and emulsifier.

3. The compound of Claim 1 wherein X is O, R is a n-decyl moiety, R' is polyethylene glycol 400, R" is hydrogen and the compound is an anionic surfactant and emulsifier.

4. The compound of Claim 1 wherein X is O, R is a n-decyl moiety, R' is sorbitol, R" is H and the compound is an anionic surfactant and emulsifier.

5. The compound of Claim 1 wherein X is O, R is a n-decyl moiety, R' is a triethanolamino moiety, R" is hydrogen and the compound is an amphoteric surfactant and emulsifier.

6. The compound of Claim 1 wherein X is O, R is a n-decyl moiety, R' is a diethanolamino moiety, R" is hydrogen and the compound is an anionic surfactant and emulsifier.

7. The compound of Claim 1 wherein X is O, R is a n-decyl moiety, R' is a sodium moiety, R" is a sodium moiety and the compound is an anionic surfactant and emulsifier.

8. The compound of Claim 1 for an emulsification process wherein said process comprises an emulsification polymerization process for emulsion polymerization of monomers comprising styrene and vinylchloride.