BACKGROUND OF INVENTION

Field of Invention

This invention relates to water dispersible, free flowing solid softening compositions for textiles and textile fibers, and a process for their manufacture.

2. Description of the Related Art

The tendency for laundered textile fibers to acquire rigidity and static charges is most pronounced when the laundry product is a synthetic detergent. Stiffness of the fibers and static charges combine to impart a palpable harshness to the textile. Articles of clothing, bed linens and the like, possessing such harshness, are irritating to the skin and uncomfortable to wear. In addition, they tend to retain wrinkles and attract dirt and dust. These undesirable consequences of laundering have been overcome by the use of quaternary ammonium compounds, among others. Quaternary ammonium compounds are currently widely used to impart softness and pliability to the textile and to diminish static charges. Quaternary compound softeners may be a component of the laundry detergent, may be added separately to the wash water at some point in the laundry cycle, or dispensed in the dryer.

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The utility of quaternary salts of dialkyldiamidoamines , especially those derived from fatty acids, as softeners for textile fibers in laundry applications, and a method for their preparation, are set forth in U.S. Patent number

3,492,324. This patent teaches that the quaternary compounds are obtained as semi-solids or solids, which are admixed with appropriate quantities of water to form pastes.. These pastes, which are • "pourable", may then further be admixed with water to form dispersions suitable for incorporation onto textiles or textile fibers for the purpose of softening them.

Aqueous pastes are by their nature incapable of being incorporated into powdered laundry products, without deleteriously affecting the free flowing characteristics of such products. Further, aqueous pastes or dispersions suffer from handling, storing, packaging, and shipping disadvantages.

Problems inherent in the use of such aqueous systems include: storage instability due to changes in temperature, which result in the separation of the quaternary compound from the water; loss of water due to evaporation, which alters the concentration of softener in the mixture and results in non—uniform application of the softener. In order for formulators to use the paste itself, it must be removed from the container and dispersed with sufficient water to obtain a softening dispersion. Bulk dispensing of a paste under these cirmcumstances is physically difficult, and results in losses of paste itself and inaccurate dispensing of softening material.

An alternative to the paste form of dialkyldiamido quaternary fabric softening compounds is as an aqueous dispersion. Such aqueous dispersions suffer from the inherent problems of aqueous pastes, and in addition, require the use of bulkier rigid metal or plastic shipping containers, which increases the cost of storage and transportation.

It is also known in the art that the dispersibility in water of such quaternary fabric softening compounds, and the stability of aqueous dispersions thereof, may be enhanced by the addition of fatty alcohols, e.g. U.S. Patent number 4,102,795.

The literature does not reveal the use of dialkyldiamido quaternary fabric softeners in particulate or powder form. The physical properties of dialkyldiamido quaternary compounds e.g. ; high viscosity in the molten state; melting range, on the order of 100°C; and a decomposition temperature of about 120°C; are not conducive to preparation of particulates or powders. We have, however, discovered a convenient method for the preparation of dialkyldiamido quaternary fabric softening compounds in the form of particulates or powders.

SUMMARY OF THE INVENTION

The present invention is directed to a particulate, water dispersible, free flowing fabric softener composition. Such a composition may be obtained by admixing an effective quantity of a processing aid, such as a polyoxyalkylene derivative, with a dialkyldiamido quaternary compound, melting them, and atomizing the molten mixture in conventional equipment appropriate for obtaining particulate material from a molten mixture. The particulate product obtained permits the use of dialkyldiamido quaternary fabric softening compound in solid laundry products without altering their free flowing characteristics. Being a solid, the particulate product does not suffer from the physical handling drawbacks associated with pastes of dialkyldiamido quaternary compounds, while at the same time, being easily dispersed in water.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to dialkyldiamido quaternary fabric softening compositions in the form of free flowing, water dispersable particulates or powders. The art in the field of dialkyldiamido quatenary compounds which function well as fabric softeners is directed to non—powders, i.e., aqueous pastes or dispersions. The physical properties of dialkyldiamido quaternary compounds are conducive to their preparation as aqueous pastes or dispersions and they are marketed and shipped to for ulators in these forms.

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The process for the manufacture of the dialkyldiamido quaternary fabric softening compounds of this invention is taught e.g. , by U.S. Patent number 3,492,324. Thus, fatty acids are reacted with diethylenetriamine in a mole ratio of 2:1. The resulting dialkyldiamidoamine is methylated by reaction with formic acid and/or formaldehyde, and the resulting dialkylamidoethyl methylamine is quaternized with conventional reagents, e.g. , dimethyl sulfate.

It is also well known in the art relating to the quaternization of amines that benzyl chloride, methyl chloride and dimethylsulfate are suitable quaternizing agents for tertiary amines, such as the dialkyldiamidomethylamine described above. Further, it is also well known in the art that methyl chloride may be reacted with secondary amines such as the dialkyldiamidoamine described above, in a mole ratio of 2:1 respectively, to produce a quaternary compound useful for fabric softening.

In order for dialkyldiamido quaternary compounds to be more widely useful as fabric softeners, especially in free flowing laundry detergent compositions, and to overcome the problems inherent in shipment, storage and use as aqueous pastes and dispersions, a particulate form of the dialkyldiamido quaternary compound is desirable. Conventional atomizing equipment to produce such particulates includes spray drying, spray congealing, and prilling devices among others. Spray drying and spray congealing, for example, necessitate pumping liquified quaternary compounds through narrow orifices under sufficient pressure to produce fine droplets; these processes have proven to be relatively expensive and operationally difficult.

The viscosity of the molten dialkyldiamido quaternary compound is such that it is incapable of being pumped neat at the maximum allowable temperature, i.e., the temperature of incipient decomposition. That is, at the maximum permissible temperature, the viscosity of the dialkyldiamido quaternary compound itself exceeds the physical limitations of conventional pumps, within the limits of economic practicality. Thus the pump cavitates or otherwise fails to transfer- the molten material from the input reservoir to the output. This condition is exacerbated when the output is a narrow constriction or orifice, as is the case in conventional atomization equipment.

Conventional atomization equipment includes devices such as spray nozzles, rotating disks, or shot towers.. Some of these devices function by forcing a liquid through narrow orifices to produce fine droplets. The droplets solidify to form the particulate. Cooling, e.g., by means of refrigerated air or other gasses, may be provided to aid solidifcation of said droplets. The range of particles in the particulate thus produced is nominally from 10 to 900 microns in diameter, with the preferred range for the use of this invention averaging from 100 to 300 microns in diameter. The orifice sizes necessary to produce this range of particulate will vary with the viscosity of the molten dialklydiamido quaternary compound, the type of atomization, and the characteristics of the ancillary equipment used to force the liquified quaternary compound through those orifices.

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The orifice sizes may range from about 0.1 to 5 millimeters in diameter.

The force necessary to atomize a liquid, by whatever means, may be supplied by mechanical pumps or by centripetal force, as is the case of spinning disks. Thus, fatty acid derived dialkyldiamido quaternary compounds, which are ordinarily solids at room temperature, must be liquified to utilize atomization equipment and thus form a particulate.

Liquification of fatty acid derived dialkyldiamido quaternary compounds may be accomplished by heating to 100 to 120°C. Higher temperatures usually result in degradation of the product as evidenced by discoloration or browning.

At approximately 120°C, the viscosity, i.e., the ability to pass through an orifice, of di (hard tallow) dia ido quaternary compounds is extremely high, and has been measured at over 160,000 centipoises. This viscosity is such as to incapacitate conventional mechanical pumps, within the limits of economic practicality, necessary to the atomization process, as has been described in the foregoing. Attempts to reduce viscosity by means of increasing the temperature results in decomposition of the quaternary compound itself. Of course, water could be added to dilute the molten mass, and thus reduce the viscosity. However, additional water sufficient to facilitate pumping results in products with unacceptably high water content. Such high water content causes the powder particles to agglomerate resulting in solids which are no longer free flowing, and which on standing tend to form solid masses.

This tendency of a powder to form solid masses is characterized as "tack". Tack may be evaluated by determining the force, in pounds, necessary to break a formed cake of the respective material. The cake is formed by compacting 450ml of product in a circular mold, 8.57cm in diamter and 12.7cm high, with a 9.98kg piston, at room temperature for 2 minutes.

Solvents other than water, for example isopropyl alcohol, may be added to reduce the viscosity of the molten quaternary compound. Sufficient quantities of isopropyl alcohol to facilitate pumping also result in unacceptably high levels of "tack". Further, isopropyl alcohol, being flammable, presents additional problems in commercial scale equipment. There is an inherent explosion hazard, and the vaporized isopropyl alcohol must be recovered from the vapor state in an environmentally acceptable manner. The equipment required to accomplish this recovery, i.e. , by condensation, is both costly and cumbersome.

It has been discovered that by incorporating an effective amount, preferably 10-S by weight of a polyoxyalkylene derivative processing aid, into molten dialkyldiamido quaternary compounds, a particulate, free flowing water dispersible fabric softener composition may be obtained by conventional atomization techniques. The addition of polyoxylalkylene derivatives significantly reduces the viscosity of the molten quaternary compound, facilitating atomization with conventional equipment, while not decreasing the free flowing characteristics or the dispersibility of the resultant particulate.

This is evidenced by little significant change in either "tack" or dispersibility, when the polyoxyalkylene processing aid is incorporated into the dialkyldiamido quaternary compound.

The polyoxyalkylene derivative that we have found most advantageous as a processing aid, is the reaction product of approximately 30 moles of ethylene oxide with one mole of the monoglyceryl ester of coconut fatty acids. We have found that the preferred amount of this polyoxyalkylene derivative processing aid is 10" by weight of the quaternary compound. More or less of the polyoxyalkylene derivative may be effective as a processing aid; from about 3 percent to about 15 percent of the dialkyldiamido quaternary compound. Less than these amounts would tend to be ineffective in reducing viscosity and more would tend to increase the "tack" of the particulate.

Other polyoxyalkylene derivatives which have been shown to be advantageous as processing aids in varying percentages from about 3 to about 15 by weight of dialkyldiamido quaternary compound, include commercially available ethoxylated sorbitan oleate derivatives, and ethoxylated fatty alcohols.

The preferred fatty acid derived dialkyldiamido quaternary compound is that derived from hardened tallow fatty acids as in Example I below.

To illustrate the efficacy of this invention, the following non-limiting examples are set forth.

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EXAMPLE 1

Dialkyldiaraidoethyl methyl ammonium methosulfate compound prepared from hardened tallow fatty acids , following the teachings of U.S. Patent number 3,492,324, was melted at 110°C and atomized through a nozzle having an orifice 1.2 microns in diameter at a pressure of 2000 psi. The atomized droplets were congealed, in air., at a temperature of 15 to 21°C and a relative humidity of 50%. The congealed particulate having a particle size range averaging from 100 to 300 microns in diameter was subsequently vacuum dried at 40°C to remove residual isopropanol, from the preparation of the quaternary compound.

^• EXAMPLE 2

To 90 parts of the quaternary compound of Example 1 were added 10 parts of the adduct of 30 moles of ethylene

® oxide and glycerol mono cocoate, (Varonic LI-63, Sherex

Chemical Company, Dublin, OH). The mixture was melted at 110°C and atomized through the identical equipment of Example 1. Only a small quantity of particulate was obtained before pumps and lines became plugged, rendering the equipment inoperable. Residual isopropanol from preparation of the quaternary compound was removed as in Example 1.

E XAMPLE 3

To 90 parts of the quaternary compound of the Example 1 were added 10 parts of isopropyl alcohol and 10 parts of ethoxylated sorbitan mono oleate, (Tween ^® 80, ICI Americas, Wilmington, DL; 20 moles of ethylene oxide per mole of sorbitan mono oleate). The mixture was melted at 110°C, and atomized, congealed and vacuum dried as in Example 1.

EXAMPLE 4

90 parts of the quaternary compound of Example I were admixed with 10 parts of ethoxylated isostearyl alcohols (Arosurf ^® AA 66E-20, Sherex Chemical Company, Dublin, OH 20 moles of ethylene oxide per mole of isostearyl alcohol), and 10 parts of isopropyl alcohol. The mixture was melted at 110°C, atomized, congealed and dried as in Example 1.

VISCOSITY:

The viscosities of the particulates obtained by atomization of Examples 1 to Example 7 were determined on a Brookfield Viscometer (Thermosel) using a #34 spindle (Brookfield Engineering Laboratories, Inc. Staughton, MA). These data are presented in Table 1:

Table 1

Product of Example Temperature ⁰ C ¹ Viscosity (CPS)

1 120 160,000 2 120 735 3 120 260 4 120 170

¹ Temperature of melted of quaternary compound (and processing aid) .

It can be observed from these data that a reduction of viscosity of at least 200 fold is obtained by the use of processing aids. Example 1, without processing aid, overwhelmed the physical capability of the spray congealing equipment (See Example 1) .

Dispersibility:

The dispersibility in water of the particulates of

Example 1 to 4 were determined by visual inspection of a mixture of 0.3 grams of product in 100 grams of water, after agitation at 32°C for 10 minutes. The results are presented in Table 2:

TAB LE 2

Product of Example Dispersibility

¹ unacceptable (not dis¬ persed)

2 ² acceptable- (dispersed"), 3 acceptable (dispersed; ;'

4 acceptable (dispersed.).

¹ Unaccep able dispersions contain solid clumps and clear areas

² Acceptable dispersions are uniformly cloudy throughout

The dispersibility of the particulate obtained by the use of a processing aid is significantly better than when no processing aid is present as in Example 1.

Tack:

The "tack" of the particulate of Example 1 to 4 was evaluated by determining the force in kilograms necessary to break a formed cake of the resepective material. The cake is formed by compacting 450 ml of product in a circular mold 8.57cm in diameter and 12.7cm high, with a 9.98kg piston, at room temperature for 2 minutes. The results are presented in Table 3.

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Table 3

Product of Example Force in kg. necessary to Break Cake

1 1.86

2 1,40 3 1.86

4 - 3.67

1* 3.44

2* >9.0

^Samples of product not vacuum dried at 40°C, i.e., containing ca. 5% by weight of isopropanol.

The presence of isopropanol significantly increases the "tack" i.e., reduces the ability of the particulate to flow freely while the preferred processing aids do not.