CA1271000A - Antistatic polyurethane foam - Google Patents

Abstract

Abstract of the Disclosure Flexible polyurethane foams having improved electrostatic properties are provided by incorporating into the reaction mixture before foaming an antistatic additive composition comprising a blend of a quaternary ammonium compound selected from the group consisting of soya dimethyl ethyl ammonium ethylsulfate, soya dimethyl ethyl ammonium phosphate, and mixtures thereof, and a plasticizer composition selected from the group consisting of N-ethyl-o- and p-toluene sulfonamide, o- and p-toluene sulfonamide, and tetrakis (2 chloroethyl) ethylene diphosphate, and mixtures thereof.

Description

~7~ )0 .. . . . . .

ANTISTATIC POLYURETHANE FOAM

This invention relates to flexible polyurethane foams exhi~iting enhanced antistatic properties, that is, foams which rapidly dissipate electrostatic charges and ~xhibit a reduced tendency to accumulate electrostatic charges. ~he flexible polyurethane foams can be produced by reactions o~ isocyanates with polyester polyols, polyether polyols, mixtures of polyether and polyester polyols, or with mixtures of polyether polyols and copoly~er polyols, ~uch as a grafted polyether containing styrene and acrylonitrile.

BACKGROUND OF THE INVENTION
Polyurethane foams, like al.mo~t all other ~ynthetic polymeric material~, tend to ac~uire and accumulate electrostatic charges. For many applications it is desirable, if not essential, to have a foam material which either does no~ acquire an electrostatic charge, or which dissipates it rapidly.
Accumulation of electrostatic changes on all types of polymeric materials has been a long-standing problem, and a variety of techniques have been ~7~

proposed to alleviate the problem. For example, additives which migrate to the surface of the plastic or fiber have been incorporated in the composition to modify its electrical properties. Antistatic resins S have been copolymerized with the base polymer in an effort to provide improved properties. Quaternary ammonium salts have been applied topically, iOe., by impregnation, or incorporated directly into the polymeric materials to provide a finished, or semi-finished product with improved antistatic properties. For example, U.S. Patent 3,117,113 with a priority filing date in 1957, discloses the use, in combination with PVC, of quaternary ammonium compounds of the general class found useful in this invention. U.S. Patents 3,335,123 and 3,407,187 disclose the use o~ quaternary ammonium compounds which are physically incorporated into polyolefins, PVC and other polymers, as by milling. None of these patents ~uggests the introduction of the quaternary ammonium compounds into the reaction mixture prior to polymer ~ormation.
~olyurethane foam can be provided with antistatic properties by one of two methods~ the in-situ production of an antistatic ~oam that has uniform properties thr~ughout its volume and cross-seGtion;
and (2) a post-treatment method in which an antistatic composition is impregnated on the surface and, to the extent possible, throughout the interior structure of the foam product. The latter technigue is the less preferable since it requires repeated handling and treatment of material thereby increasing its cost it provides less uniform properties, which properties may indeed be only superficial if the thickness of the ~oam material is substantial; and the impregnant is ~2~7~0~3 ~ubject to removal by wear and tear if the impregnated product is used over again. If used for packing sensitive electronic component~, such as computer chips, the impregnated composition may attach to, and damage the article. Of cour6e, in some applications such as laundry softeners or antistatic agents, it is intended that the impregnated foam lose its antistatic coating as it i~ transferred to the damp laundry during use in the dryer. ~owever, in most applications it is desirable for the foam product to exhibit both permanent and uniform antistatic properties which will render the product electrostatic free. The characteristics of packaging materials used for a variety of ~ensitive electronic components and devices are 6et forth in the military specification Mil. B B1705B.
It is known that certain quaternary a~monium 8alts can be added during the manufacture of polyurethane foam to impart improved antistatic properties to the cured foam. United States Patent 3,933,697 discloses specific quaternary ammonium salts that can be incorporated as an ingredient into the composition prior to commencement of the foam-formins reaction; alternatively, it is suggested that the ~ame compounds can be applied by impregnation to the ~inished urethane foam.
While the advantages of incorporating an additive by the in-situ method which will render the finished product antistatic are obvious, the selection o~
appropriat~ materials must be based upon their compatibility in the foam making process, and on their effect on the physical appearance and characteristics of finished foam product. This is 80 because the ~oam-forming reaction requires a careful balancing of ~L~7~lOO~

the polymerization, or gellation, reaction with the ex~ansion of the foam-forming ingredients to provide a uniform cell structure, the avoidance of ~plits, cracks and other defects, and finally the polymerization which must be completed within a critical time period to insure a self-sustaining and 6table foam structure. The presence of even small quantities of additional compounds can have a markedly adYerse effect on the reaction mechanism and the finished product. Those familiar with the art will know of the adverse effects of low levels of contaminants or impurities which may be barely detectable.
It is therefore essential in seeking an agent or additive which will render the finished foam antistatic, to find a compound or composition that is totally compatible with the foam making process.
Other factors which must be taken into account are (1) the ability to mechanically incorporate the antistatic additive into the ~oam-forming composition using conventional equipment: and (2) the cost of the additive at its effective level or within its effective ran~e and its impact on the final cost of the foam.

SUMMARY OF THE INVENTION
It has now been found that ~ertain ~uaternary ammonium compounds, when combined with plasti~izers, and preferably those plasticizers which are liquids, form a solution which can be incorporated into the polyurethane foam making composition to provide remarkably improved antistatic properties in the finished foam product.

~7~)00 The quaternary ammonium compounds found to produce a synergistic result in the practice of this invention are commercial products.
One o~ the quaternary ammonium compounds found to be useful in the practice of the invention is soya dimethyl ethyl ammonium ethylsulfate, and specifically the product sold under the trademark Larostat 264-A
by Jordan Chemical Company of Folcroft, Penn. The product is a wa~y solid which can be converted to a pourable li~uid by heating to 50C-65~C. Jordan Chemical markets this product in the form of a li~uid blend of the quaternary ammonium compound in twenty percent dipropylene glycol ~DPG) as Larostat 377, and it can also be used in the practice of the invention.
Another quaternary ammonium compound found to be useful in the practice of the invention is soya dimethyl ethyl ammonium ethylphosphate, ancl ~peci~ically the product sold under the trademark Larostat 192 by Jordan Chemical. This product ? S a pourable liquid which can be mixed with the other components to produce the antistatic additive composition which are incorporated into the ~oam-forminy mixture. The preferred quaternary ammonium compound i~ the soya climethyl ethyl ammonium ethylsulfate of Larostat 264-A.
The plasticizers o~ this invention found to provi~e the markedly improved antistatic properties when used in combination with the above quaternary ammonium compounds are also commercially available products.
The plasticizer compositions found to be use~ul in the practice of this invention are as follows: the mixture of N-ethyl-o- and p-toluene sulfonamide, sold by Monsanto Chemicals under the trademark Santicizer ~27~ )0 8; the mixture of o- and p-toluene sulfonamide, sold by Monsanto Chemicals under the trademark Santicizer 9; and tetrakis(2 chloroethyl) ethylene diphosphate sold by Olin Chemical Company under the trademark Thermolin 101. Santicizer 8 is the preferred plasticizer compound and is a light yellow, viscous liquid, which is a mixture of the ortho and para isomers. Santicizer 9 is a white to light-cream granular ~olid, also a mixture of the ortho and para isomers. The Thermolin lOl product is a liquid, and has utility as both a plasticizer and a flame retardant~
In the examples which follow, the various quaternary ammonium compounds and plastici~ers which wera used are, for convenience, identified by their commercial names, or abbreviations.
Most significant is the discovery that guaternary ammonium compounds, which ~re solids at ambient temperature and pressure, when di6solved with plasticizers to provide an antistatic additive composition, exhibit a ~ynergistic effect when added to the foam-forming reactants and provide a finished foam having greatly improved antistatic properties.
This ~ynergism i~ demonstrated by the fact that when ~nly the quaternary ammonium compounds alone, or the plasticizers of the invention are added to the foam-forming mixture no signi~icant improvement of antistatic properties in the finished foam are observed. Polyurethane foams made with one or the other of the compounds exhibit essentially the same antistatic properties as foam containing no antistatic additives.
The preferred combination of quaternary amm~nium salts and plasticizers of this invention provide a ~273~0() stable solution, that is, one which does not separate on standing, solidify on cooling or produce a precipitate. The stability of the antistatic additive solution is extremely important from the standpoint of commercial production. Polyurethane foam.s are made by continuous casting methods which are capable of, and are most efficient when they are--run-for ---~everal hours, or throuyhout an entire shift.
Additive streams must be fed from storage vessels to the mixing head throughout this period. Such additives must be stable over the daily production period, and preferably should be stable over periods of at least several days. The preferred antistatic additive ~olutions of this invention meet those cri~eria.
The antistatic additive solutions of this invention are prepared by mixing one part by weight of the quaternary ammonium compound in from about 0.4 part to three parts of liquid or solid plasticizer.
Significantly enhanced antistatic properties have been obtained when the antistatic additive composition is comprised o~ one part of quaternary ammonium compound and one and one-half parts of plasticizer.
In a preferred embodiment of the invention the quaternary ammonium compo6ition of larostat 264-A, which is a waxy solid at room temperature, is heated to between about 50C and 65C, and when it melts and is flowable, is poured into the liquid plasticizer, which is preferably the N-ethyl-o- and p-toluene sulfonamide mixture of Santicizer 8. This mixture is then drum rolled or mixed with an impeller for a short time to ohtain a clear homogeneous solution. This mixture is stable and no phase separation is observed at high or low temperatures.

~7~

The ~uaternary ammonium composition of Larostat 264-A can also be blended into okher plasticizers or into polyols using the same general procedure~ In some instances, some phase separation may be observed as the mixture cools. Any phase separation which does occur can be minimized, if not eliminated entirely, by maintaining the mixture at a higher than normal temperature. As will be apparent to one skilled in the art, adjustments to the foam formulation can be made to take account of the higher temperature of the foam forming composition and reaction.
As noted above, the antistatic additive composition of this invention is added to the foam-~orming reactants at the time of mixing. It can be combined in a prepolymer mix, or added as a separate metered stream in accordance with techniques well-known to those familiar with the art. Noticeable ~mprovements have been observed with the incorporation o~ from about 5 to about 25 parts of antistatic additive solution per lOO parts of polyol or resin.
The term resin as used here is synonymous wi'h polyol and includes polyester and polyether polyols, and mixtures thereof. The term ~phr~ means ~parts per hundred of resin.~ ~he preferred level of antistatic additive 601ution iS ~rom about 17 to 22 parts per 100 parts of polyol.
The polyurekhane foams of this invention can be manufactured by the one-shot or prepolymer methods, and can consist of polyester polyols, polyether polyols, or polyurethanes prepared from a blend of polyester and polyether polyols, and of blends of polyether and copolymer polyols, all of which are described in more detail below.

Polyurethane foams exhibiting improved antistatic properties have many applications including use in operating rooms where sparks can present a serious fire hazard; in connection with sound proofing and vibration damping materials for computers; and in the packaging and handling of sensitive electronic components such as computer chips where the presence of static electricity can modify or damage the article so that it cannot be used.
In the examples which follow the polyether polyol resin used had an average molecular weight of 3S00, unless otherwise indicated. The copolymer polyol was a grafted polyether polyol containing copolymerized styrene and acrylonitrilel which was cupplied by Dow Chemical U.S.A. under the designation XAS-10963.01.
Other copolymer polyols which can be used in this invention are available from Union Carbide Corp. and from BASF Wyandotte.
The polyester resin has an average molecular weight of 2000.
The isocyanate used was tolylene diisocyanate, (also referred to as toluene diisocyanate, or simply TDI) which was 2n isomeric mixture of the 2,4 isomer (67~) and the 2,6 isomer (33%~) In some instances the isomeric mixture of the TDI was 80/20, respectively. Unless otherwise indicated, the TDI
Index was 105. The utility of the invention is not limited to any particular isomeric ratio, or to any specific TDI Index value. Other isocyanates conventionally used in the manufacture o~ polyurethane foams can be u~ed. These would include 4,4'-diphenylmethane diisocyanate (MDI), and othere well-known to those ~amiliar with the art.

o~o DETAI:LED DESCRIPTION OF THE INVENTION
In the co:mparative the basic ~oam formulations are selected :from those known in the art, and the individual components are commonly available and widely used. Similarly, in those examples which illustrate the claimed invention, apart from the novel combination o:E guaternary ammonium compounds and plasticizers which produce the improved electrostatic propertie~ in the finished foams, the components and 1 n their relative proportions are assumed to be well within the skill of the art.
The following csmponents used in the examples are identified as follow~:
1. Amine catalysts -A-l, 70% bis~2 dimethyl aminoethyl) ether in DPG sold by Union Carbide Corp.
A-30, silicone amine sold by Union Carbide 33-L~, 33% triethylene diamine in DPG sold by Air Product6 Corp.
NCM, N-coco morpholine ~old by Lonza Chemical 16 D, N-hexadecylmethyl amine sold by Lonza Chemical NEM, N-ethyl morpholine sold by Texaco M-6682, a mixture o~ :Eatty acid amides, sold by Witco Chemical

2. Organotin catalysts -C-4, 50~ stannous octoate in DOP sold by Witco Chemical

3. Silicone ~urfactants:
L-530, silicone copolymer ~old by Union Carbide L-560, silicone glycol copolymer sold by Union Carbide o~

-l:L-L-5750, silicone glycol copolymer sold by Union Carbide DC-200, dimethyl polysiloxane from Dow Corning

4. Flame ~e ardant -DE-60FI pentabromo diphenyl oxide blended with 15~ aromatic phosphate, sold by Great Lakes Chemical In the examples, the quantities of all of the - 10 components are expressed in term~ of parts ~y weight of ingredients per 100 parts of re~in, (i.e., polyol), or ~phr.~
In addition to the major ingredients whi~h are indicated by their proportions in the following examples, the polyether foam formulations also included minor amounts of cataly~ts, stabilizers, accelerators, activators, surfactants, and other functional additive~ well known in the art. On average, the total of these other additives amounted to from about 2 to 3 parts by weight per 100 parts by weight of the polyol. In the examples which follow, unless otherwise specified, the components and ranges employed are:

TABLE_I
Silicone surfactant (L-5750) : 1.0 - 1.3 phr.
Oxganotin Catalyst ~C 4) : 0.85 - 1.2 phr.
Amine Catalyst (A~l) . 0.30 - 0.375 phr.
(33-L~) : 0.10 - 0.125 phr.

In the examples, the total quantity of these compounds is relatively ~mall compared to the other ingredients. As is well known to those familiar with ~7~

the art, their selection and the actual quantities employed are routinely varied in response to the ambient conditions of temperature and humidity, as well as the mechanical conditions relating to foam manufacture. In the interests o~ exemplifying the invention, the total quantity of these components identified in Table I appears in the Components column~
adjacent the entry ~Catalyst, etc.

Test Method In determining the antistatic properties of the polyurethane foams described in the examples which follow, the ~tatic decay rate method as described in Federal ~est Method Standard No. lOlC-4046 1 was used. In gPneral, this test ~ethod is used to determine the ele~trostatic properties of materials in film and heet form by measuring the intensity and polarity of an induced charge and the time required for dissipation o~ the charge. In this test procedure, a static charge of 5000 volts is first applied across the foam ~ample and then the voltage ~ource is removed and the sample is grounded. The foam sample and the test chamber are maintained at a relative humidity of about 15%. The time of static decay to zero VoltB i6 determined from a moving paper chart on which the drop in voltage is recorded. A
value of less than 2 seconds for the decay time is established for the foam product in order to pass this test, and to insure that sensitive electronic compollents and like which are placed in contact with the foam will not be damaged.
A conventional flexible polyether polyurethane foam was prepared as a hand batch from a standard formulation using a polyol having an average molecular ~7~ t)O~) ;13 weight of 3000 and tolylene diisocyanate (80/20) with an Index of 115. When tested a~s described in FTMS
No. 101C-4046.1, the cured sample maintained its initial 5KV charge and no decay over time was observedO A conventional polyester polyurethane flexible foam was also prepared as a hand batch from a ~tandard f~rmulation using~a~polyester~--resin and tolylene diisocyanate (67/33). When tested as described above, the foam sample maintained the initial impressed charge of 5KV with no observed decay over time.

PREFERRED EMBODIMENTS
The examples which follow illustrate the invention in various foam formulations.

.Example I (349-10-C) Component Parts Polyether 100 Tolylene diisocyanate ~TDI) 46.24 Catalyst, etc. 2.7 Water 3.5 Antistatic Additive:
264-A 8.0 Santicizer 8 12.0 The above composition wa~ prepared as a hand batcb and a ~ample was cut from the cured foam for static decay testing in accordance with the method described above. The initial potential after the voltage ~ource was removed was 5.0 XV and derayed to zero volts in 1.39 seconds.

- 1~7~00~

Examples II through V
In each of these examples the polyol was a blend of the polyether resin used in Example I, and a copolymer polyol which incorporates styrene and acrylonitrile~

Parts (349-9-A) (348-38-D) (349-6-A) (349-~-C) Components Ex. II Ex. III Ex. IV Ex._V _ Polyether 70 70 70 70 Copolymer Polyol 30 30 30 30 TDI 38.6 41.64 38.6 38.6 Catalyst, etc. 2.40 2.6 2O45 2.50 Water 3.1 3.1 3.5 3.5 Antistatic Additive:
264-A 8.0 8.0 10.0 8 ` Santicizer 8 12.012.0 15.0 12 Cured samples from each of these hand batches were tested as described above to determine the time for decay to zero volts with the following results:
Example Time (seconds) II 1:00 III 1.20 IV 0.88 V 0.94 \

Exam~e_VI
In this example, a polyether polyol having an average molecular weight of 3000 was employed. A red color dispersion was added to impark a pink color to the foam.

.

a) Components Parts Polyether 100 Tolylene dii~ocyanate44.78 Catalyst, etc. 2.3 Water 3.4 Red color .15 Antistatic Additive:
264-A 7.0 Santicizer 8 lOo 5 lOA cured sample ~rom the hand batch tested in accordance with the method described above decayed to zero volts in 1.36 second~.

Examples VII and VIII (349-43-C and 349-44-A) In these examples a polyester polyol was employed 15and appropriat~ changes in the formulation were made.

Parts (349-43-C) (349-44-A) Components Ex. VIII Ex. IX~
Polyester 100 100 TDI (80/20) - Index 102 4401 TDI ~67/33) - Index 112 - 50.S
Catalyst (C-4)* 0.50 0.30 ~-532* 1.3 NEM/A-30 (.45/.20)* .75 D~16-D* .15 0.10 33-LV* - .50 M 6682* - 1.2 NCM* - 1.0 ~L27~

Antistatic Additive:
264-A 8.0 8.0 Santiciæer ~ 12.0 12.0 Water 3.6 3.7 *[As previously defined]

Cured samples from these polyester ~oam hand batches were prepared and tested in accordance with the method described above. The decay times to zero volts were 0.8~ seconds for the foam of Example VII
and 0.56 seconds for the foam of Example VIII.

Comparative Examples A-E
In order to determine what effects, if any, each of the antistatic additives would have if used separately, two comparative examples were prepared using the poly2ther resin (3000 M.W.) and essentially the same basic formulation in Example VI with the following exceptions:
Comparative Example A contained 17.5 phr of the mixture of N-ethyl-o-and p-toluene sulfonamide, and no quaternary ammonium compound: and Comparative Example B c~ntained 17.5 phr of soya dimethyl ethyl ammonium ethylsulfate, (Larostat 264-A), and no liquid plasticizer. Cured æamples of foam prepared from these two hand batches were tested as described above.
The samples carried a significant initial charge, and there was no observed decay of voltage with time from that as originally measured on these comparative ~amples. The results of the testæ on the foam samples of Comparative Examples A and B establish a synergistic effect of the solution of the specific quaternary ammonium compound of Larostat 264-A and the Santicizer 8 plasticizer~

~L~7~0~) A third comparative example, Example C employing the polyether resin (average MW of 3500), and only Larostat 264-A was prepared as follows:
Exam~.le C
Components Parts Polyether 100 TDI S80/20) 43.6 C-4* .45 A-l* .l9 33-LV* .06 Water 3.5 Larostat 264-A 1.0 *[As previously defined~

A cured sample of this polyether foam of Example C
was taken from the hand batch and tested in accordance with the method described above. The initial charge of ~.5KV was not observed to decay over time.
Further comparative foams of Examples D and E
were prepared to determine the effect of the separate addition of plasticizer and guatsrnary ammonium composition to a polyester polyurethane composition.
The~ were prepared using the same foam formulation used in Example IX. In comparative Example D, only the plasticizer Santicizer 8 was used at a level of 20 phr. At this relatively high level, which is the maximum compatibility level recommended by ~he manufacturer for use with non-~oam polyurethane polymer compositions, the cured sample exhibited a decay time o~ 5.34 seconds. Comparative Example E
was prepared as a hand batch by heating the quaternary ammonium compound Larostat 264-A, adding it to the polyester polyol and then mixing it with the remaining components. The resin mixture was cloudy aft~r ~7~1L0~3 addition o~ the ~uaternary ammonium compound and the resulting product collapsed, did not produce a ~oam, and was not tested.

Examples IX~ X and XI (353-26-A; -B; -C) In these three examples the TDI had an Index of 108 and a red pigment was added to provide the ~ ~~~~
finished f oam with a pink color.

Parts (353-26-A) (353-26-B) (353-26-C) Components ~x. IX E~ Ex._XI
Polyether 100 103 100 TDI ~67/33) 44.78 44.78 44.78 Catalyst, etc.2.45 2.45 2.30 Water 3.4 3.4 3.4 Antistatic AdditiYe:

192 - 7.0 8.8 Santicizer 8 10.5 10.5 13.2 Samples ta~en from the hand batches prepared from the above ~ormulations were subjected to the static decay testing method previously described (1) on the day o~ their preparation, ~nd t2) following aging o~
20 minutes in an oven at 70~C, 30 minutes in a dessicator, and 24 hours in a temperature and humidity control chamber.

The decay times to zero volts were ~ Ex. X Ex. XI
Initial 0.46 0.92 0.42 Aged 0.61 1.58 0.63 i27~

Example XII (353-lO-~On) In this example the polyether polyol has an Index of 108, and the plasticizer is a blend.

Com~onent Parts Polyether 100 TDI (67/33) ~ 44.78 Catalyst, etc. 2.30 Water 3-4 Antistatic additive:
264-A 7.0 Santicizer-8 11.0 Santicizer-9 2.0 A ~ample taken ~rom the hand batch is tested for static decay as previously described. ~he time for ~5 decay to zero volt8 iS 1 . 95 ~econds.

Example XIII (349-6-B) The following example demonstrates that the antistatic additive is compatible with a liquid flame retardant compound sold for use with flexible polyure-thane foams. ~he flame retardant identified as DE-60F
i6 pentabromo diphenyl oxide b:Lended with 15% of an aromatic phosphate sold by Great Lakes Chemicals.

Components ~E~
Polyether polyol 70 Copolymer polyol 30 TDI ~67/33) 38.6 Water 3.5 Catalyst, etc. 2.45 DE-60F 5.0 ~7~

Antistatic Additive:
264-A 6.0 Santicizer 8 9.0 The above composition is prepared as a hand-batch and produces a satisfactory ~oam. After curing a sample is tested and found to have a static decay period of less than 2.0 seconds.

Examples XIV and XV (363~ A and C) In these examples the urethane foam-forming reac-tion mixture comprises a blend of polyether and poly-ester polyols. The diisocyanate has an Index of 112.

Components Parts (363~ A) (363-11-C) Ex. XIV Ex. XV
Polyester 15 15 Polyether 85 85 TDI (80/20) 48 48 C-~* 3.5 3.5 L-560* 4.3 4.3 DC-200* -- .1 A-1/33-LV (3/1)* .35 35 Red color .20 .20 Antistatic-Additive:
264-A 7.0 7.0 Santicizer 810.~ 19.5 *[A~ previously defined]

Samples taken from each of the hand batches were tested as previously described. The time to decay to zero volts for the foam o~ Example XIV is 1.67 seconds and for that of Example XV was 1.33 seconds.

~7~LOOO

Examples XVI and XVII
In these examples a polyether polyurethane ~ormulation essentially thP same as that of Example VI was employed with the exception that the antistatic additive composition was a mixture of three parts of the liquid flame retardant-plasticizer tetrakis (2 chloroethyl) ethylene diphosphate to two parts of the quaternary ammonium composition of Larostat 264-A.
~he flame retardant-plasticizer is sold by Olin Chemicals under the trademark THERMOLIN~ 101 and is identified as TM-101.

Components Parts (363~10-B3 ~363-10-C) Ex. XVI Ex. XVII

Polyether 100 100 TDI 44.8 44.8 Catalyst, etc. l.9 1.9 Water 3.4 3~4 Red color 0.2 0.2 Antistatic additive:
TM-101 13.2 15 264-A 8.8 10 Cured samples prepared from the hand batches were tested as described above. The decay time for Example XVI was 2.00 seconds and for Example XVII was 1.61 seconds.

Additional Comparatlve Examples Additional formulations were prepared using, the plasticizer San~icizer 8 with other quaternary 3L~7~

a~monium compounds. These included solutions of 1.5 parts Santicizer 8 to 1 part Arquad ~D60~0 and Igepal 887. Arquad RD6080 is a proprietary quaternary ammonium compound sold by Akzo, and Igepal 887 is a 70% nonyl phenoxy polyethanol in water sold by GA~.
Solutions of these additives were incorporated at levels ranging from 7 phr to 17.5 phr of polyether re in in hand batches. Samples cut from the cured foam and subjected to ~tatic decay testing showed no appreciable loss of accumulated static charge over time~
Another series of tests were conducted to dete~mine whether other Xnown plasticizers could ~e used with the preferred quaternary ammonium compound Larostat 264-A to produce an effective antistatic additive composition. Solutions of 1 part Larostat ~64-A to one and one-half parts of each o~ the following compounds were prepared: (1) benzyl phthalate; (2) dioctylphthalate, or DOP; and (3) cresyl diphenyl phosphate, or CDP. These solutions were added at a level of 17.5 phr in a formulation similar to that ~f Example IX. Hand batches were prepared and cured. Samples tested showed no observable decay in static charge for examples using benzyl phthalate or DOP; the sample containing CDP
showed a decay rate of approximately 6.7 seconds.
While certain representative embodiments and details have been shown ~or the purpose of illustration, numerous modifications to thP foam formulations previously described can be made without departing from the invention disclosed.

Claims (20)

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

1. In the method of preparing a flexible polyurethane foam from a polyol and a polyisocyanate the improvement which comprises adding to the foam-forming composition from about five to about 25 parts by weight per 100 parts by weight of polyol of an antistatic additive composition comprising one part by weight of a quaternary ammonium compound selected from the group consisting of soya dimethyl ethyl ammonium ethylsulfate, soya dimethyl ethyl ammonium ethylphosphate, and mixtures thereof and from about 0.4 to about 3 parts by weight of a plasticizer composition selected from the group consisting of N-ethyl-o- and p-toluene sulfonamide, o- and p-toluene sulfonamide, tetrakis (2 chloroethyl) ethylene diphosphate, and mixtures thereof, to provide a foam having a reduced tendency to develop and accumulate electrostatic charges.

2. The method of claim 1 where the antistatic additive composition is comprised of one part of quaternary ammonium compound to about one and one-half parts of plasticizer.

3. The method of claim 2 where the plasticizer is a liquid, and the quaternary ammonium compound is dissolved in the liquid plasticizer.

4. The method of claim 1 where the quaternary ammonium compound is soya dimethyl ethyl ammonium ethylsulfate.

5. The method of claim 4 where the plasticizer is a mixture of N-ethyl-o- and p-toluene sulfonamide.

6. The method of claim 1 where the polyol is selected from the group consisting of polyester polyol, polyether polyol, and mixtures thereof.

7. The method of claim 1 where the polyol is a blend of polyether polyol and a graft copolymer of polyether polyol and copolymerized styrene and acrylonitrile.

8. The method of claim 1 where the antistatic additive composition is prepared by mixing the quaternary ammonium compound and the plasticizer in the polyol.

9. An antistatic flexible polyurethane foam containing an effective amount of an antistatic additive composition comprising one part by weight of a quaternary ammonium compound selected from the group consisting of soya dimethyl ethyl ammonium ethylsulfate, soya dimethyl ethyl ammonium ethylphosphate, and mixtures thereof in combination with from about 0.4 to about 3 parts by weight of a plasticizer selected from the group consisting of N-ethyl-o- and p-toluene sulfonamide, o- and p-toluene sulfonamide, tetrakis (2 chloroethyl) ethylene diphosphate, and mixtures thereof.

10. The antistatic polyurethane foam of claim 9 wherein the antistatic additive composition is comprised of one part of soya dimethyl ethyl ammonium ethylsulfate dissolved in about one and one-half parts of a mixture of N-ethyl-o- and p-toluene sulfonamide.

11. The antistatic polyurethane foam of claim 9 which contains from about 5 to about 25 parts by weight per 100 parts by weight of polyol (phr) of the antistatic additive composition.

12. The antistatic polyurethane foam of claim 11 which contains from about 15 phr to about 20 phr of antistatic additive composition.

13. The antistatic polyurethane foam of claim 11 which contains about 18 phr of antistatic additive composition.

14. An antistatic additive composition for in situ use in the manufacture of a flexible pplyurethane foam exhibiting a reduced tendency to acquire and accumulate static charges comprising a stable liquid mixture of a quaternary ammonium compound selected from the group consisting of soya dimethyl ethyl ammonium ethylsulfate, soya dimethyl ethyl ammonium ethylphosphate, and mixtures thereof and a plasticizer composition selected from the group consisting of K-ethyl-o- and p-toluene sulfonamide, o- and p-toluene sulfonamide, tetrakis (2 chloroethyl) ethylene diphosphate, and mixtures thereof.

15. The antistatic additive composition of claim 14 where the quaternary ammonium compound is soya dimethyl ethyl ammonium ethylsulfate and the plasticizer is a mixture of N-ethyl-o- and p-toluene sulfonamide.

16. The antistatic additive composition of claim 15 which is prepared by heating the soya dimethyl ethyl ammonium ethylsulfate to a temperature in the range of 50?C to 60?C and adding it to the liquid N-ethyl-o- and p-toluene sulfonamide mixture.

17. The antistatic additive composition of claim 14 which comprises one part by weight of the quaternary ammonium compound and from about 0.4 to about 3 parts by weight of the plasticizer composition.

18. Flexible polyurethane foam produced according to the method of claim 1, 2 or 3.

19. Flexible polyurethane foam produced according to the method of claim 4, 5 or 6.

20. Flexible polyurethane foam produced according to the method of claim 7 or 8.