Methods of making antistatic vinylaromatic-containing articles

A method of making antistatic vinylaromatic polymer-containing articles, and articles produced thereby, which includes immersing expandable vinylaromatic polymer-containing articles, having a blowing agent dispersed therein, in a bath containing an ethoxylated amine compound for a length of time sufficient to allow the ethoxylated amine compound to penetrate into the expandable articles to an extent such that the expandable articles, when expanded to a density of at most about 1.5 pcf, dissipate an induced 5000 volt charge to substantially 0 volts in less than 2 seconds.

TECHNICAL FIELD 
This invention relates generally to methods of making antistatic expandable 
and expanded vinylaromatic polymer-containing articles and the articles 
produced thereby. 
BACKGROUND OF THE INVENTION 
Current loose-fill packing materials, such as expanded polystyrene pellets, 
are well-known to acquire excessive static electricity, resulting in 
either being undesirably attracted to or repelled by surrounding objects. 
Common solutions to relieving the polystyrene pellets of static include 
either spraying or dipping pre-expanded or expanded polystyrene pellets 
with antistatic solutions to surface-treat the polystyrene pellets. 
However, with these methods, the antistatic durability is often inadequate 
because the coating can peel off, rub off, or be rinsed off the pellets. 
In addition, uniformity of coating is difficult to achieve, resulting in 
less than adequate static dissipative properties or higher costs of labor 
and materials to assure uniformity. 
Another prior art method for relieving loose-fill packing materials of 
their static properties is by mixing an antistatic agent into the pellet 
material during extrusion. However, this method often results in 
undesirable nucleation or foaming of the product, reaction with fire 
retardants or other materials added to the pellet material, and/or poor 
static dissipative qualities. 
Examples of previous attempts to solve the antistatic problem or related 
problems are described in the following patents: 
U.S. Pat. No. 4,808,448 issued Feb. 28, 1989 to H.S. Cox discloses a 
process of combining an antistatic agent with thermoplastic beads to be 
pre-expanded in which the antistatic agent is combined in sufficient 
amounts either: (a) with thermoplastic beads to be expanded prior to 
injection into a pre-expander and thereafter injecting the combination of 
the thermoplastic beads and the antistatic agent into the preheated 
pre-expander for pre-expanding the beads; (b) with the beads in a 
preheater shortly after injection of the beads into the preheated 
pre-expander; or (c) in liquid form with dry steam for delivery to a 
molding cavity of a mold for intermixing with pre-expanded beads. If the 
antistatic agent to be combined with the bead is in liquid form and is to 
be mixed with the bead prior to being added to the heated pre-expander, 
the antistatic agent is mixed with the bead and thereafter the combination 
is heated to permit the expansion of the beads and atomizing of the liquid 
antistatic agent filling the space of the environment uniformly coating 
the expanding bead. Alternatively, if the antistatic agent is in liquid 
form, the liquid antistatic agent may also be injected into a heated 
environment separately from the bead wherein it atomizes, filling the 
environment, uniformly coating the expanding bead when added. Suitable 
antistatic agents disclosed include quaternized ethoxylated amines, for 
example, quaternized coconut amine ethoxylate. U.S. Pat. Nos. 4,696,950 
and 4,771,081 to H.S. Cox are related to U.S. Pat. No. 4,808,448. 
U.S. Pat. No. 4,785,032 issued Nov.15, 1988 to R.E. Touhsaent discloses a 
water-based antistatic coating composition comprising at least one 
water-soluble antistatic agent, which may be applied to a polymer film 
substrate and, upon drying, forms an adherent antistatic coating. 
U.S. Pat. No. 4,603,149 issued Jul. 29, 1986 to H.S. Kesling, Jr. et al. 
discloses that dialkyl bisalkoxylated quaternary ammonium salts, when 
coated onto the surface of expandable styrene polymer particles, serve as 
an antistatic and anti-lumping agent for the particles. It is further 
disclosed that the ammonium salts may be coated onto the styrene polymer 
by any suitable method, such as dry blending in a mixer or solution 
coating followed by evaporation of the solvent. The patent teaches that 
certain quaternary salts may be added to the polymer particles during 
impregnation of the polymer with a blowing agent. 
U.S. Pat. No. 4,393,176 issued Jul. 12, 1983 to W. Lybrand discloses adding 
chemical components to thermoplastic materials to reduce the electrical 
resistivity of the material. The chemical component or agent may be an 
amine when the thermoplastic material is a polystyrene or a modified 
styrene. The amine is preferably ethoxylated. It is disclosed that the 
material may be formed into sheets as by extrusion or may be injection 
molded into different members such as panels. The material may be formed 
by mixing the ethoxylated amine and the polystyrene and extruding the 
mixture. 
U.S. Pat. No. 4,393,159 issued Jul. 12, 1983 to W. Lybrand discloses 
polypropylene articles in which the accumulation of static charges is 
inhibited by adding, e.g., ethoxylated amines to the polypropylene. 
U.S. Pat. No. 4,369,227 issued Jan. 18, 1983 to K. Hahn et al. discloses 
particulate styrene polymers containing blowing agents which are 
surface-coated with a hydroxycarboxylic acid ester or an ester of a 
carboxylic acid with an oxyalkylated alcohol. The patent teaches that the 
esters are present predominantly as a uniformly distributed coating on the 
surface of the expandable polystyrene particles. The method of application 
of the coating is not critical; for example, simple tumbling of the finely 
divided ester with the styrene polymer particles in a commercial mixer may 
be used. It is also possible to apply the ester from a aqueous dispersion 
or a solution in an organic solvent, in which case the solvent or water 
must be removed during application. It is also possible to add the esters 
to the styrene bead polymerization charge at or towards the end of the 
suspension polymerization process. 
U.S. Pat. No. 4,333,970 issued Jun. 8, 1982 to E.A. Blommers et al. 
discloses coated styrenic polymer beads which exhibit anti-lumping 
properties upon pre-expansion produced by forming a suspension of styrenic 
polymer beads in an aqueous medium and adding thereto, under 
polymerization conditions, an emulsion which contains a styrenic monomer 
and a catalyst therefor, and an isoprene or butadiene-styrene 
macromonomer, the emulsion formed in an aqueous medium containing a 
polyoxyethylene alkylphenol. The mixture so formed is maintained at an 
elevated temperature so as to form a polymerized coating about the initial 
styrenic beads. The beads, so produced, are then impregnated with an 
expanding agent. 
U.S. Pat. No. 4,333,969 issued Jun. 8, 1982 to H.A. Wright et al. discloses 
a process for forming styrenic polymer beads having a preferred bead 
diameter from styrenic polymer beads having a smaller diameter which 
comprises forming a suspension of the small styrenic polymer beads in an 
aqueous medium with the aid of a finely divided, water-soluble inorganic 
phosphate suspending agent and a modifier therefor; forming an emulsion of 
styrenic monomer containing a free radical-producing catalyst in an 
aqueous medium, using a non-ionic surfactant that is an ethylene oxide 
condensate of an alkylphenol; and adding the styrenic monomer-catalyst 
aqueous emulsion to the styrenic polymer bead suspension in polymerizing 
the styrenic monomer about the styrenic beads. 
U.S. Pat. No. 4,314,040 issued Feb. 2, 1982 to A.J. Castro et al. discloses 
a concentrated antistatic composition adapted for incorporation into 
various polymers such as olefins prepared by admixing a liquid ethoxylated 
amine antistatic agent, such as an N, N-bis-(2-hydroxyethyl) alkenyl or 
mixed alkenyl and alkyl amine, with various polymers such as, for example, 
polystyrene, heating to form a homogeneous liquid and rapidly cooling the 
mixture to form a solid antistatic agent. A normally liquid antistatic 
agent can thus be blended into a polymer such as polystyrene as a 
dry-solid product to impart antistatic properties to the blended resin. 
Examples of the amine antistatic agents are diethoxylated tallow (mixed 
alkenyl and alkyl) amine, and diethoxylated coco amine. U.S. Pat. No. 
4,314,040 is a division of U.S. Pat. No. 4,210,556 which is a division of 
U.S. Pat. No. 4,147,742. 
U.S. Pat. No. 4,281,036 issued Jul. 28, 1981 to H. Leithauser et al. 
discloses fine particulate expandable styrene polymers having coatings 
applied thereto by: (a) introducing the fine particulate expandable 
styrene polymers into a closed mixing vessel; (b) reducing the pressure in 
the mixing vessel below atmospheric; (c) preparing dispersions of the 
coating materials and heating the dispersions to about 30 to 90.degree. 
C.; and (d) aspirating the heated dispersions of the coating materials 
into the mixing vessel while simultaneously mixing the dispersions with 
the particulate styrene polymers to form a coating thereon and drying the 
coated particles. The patent teaches that especially advantageous 
dispersions contain mixtures of monostearates and distearates of glycerin 
or the sorbitol ester of palmitic acid as the dispersing agents. Further, 
mixtures with dispersing agents of metallic soap such as magnesium zinc 
stearate or calcium stearate bisstearylethylenediamine are also used 
advantageously. 
U.S. Pat. No. 4,020,133 issued Apr. 26, 1977 to T. Altares, Jr. discloses a 
collagen-aluminum complex which is dispersed in water, serving as a 
suspension agent for suspending polystyrene beads during impregnation of a 
blowing agent. The aqueous system is drained from the impregnated 
expandable beads, which are washed, but which retain adherent deposits of 
the collagen-aluminum complex. The dry coated beads are said to have 
minimized propensity toward lumping when pre-expanded. 
U.S. Pat. No. 4,018,946 issued Apr. 19, 1977 to M. Klein discloses a method 
for producing expandable discrete styrene-polymer bit-pieces impregnated 
with a liquid aliphatic impregnant, wherein a quantity of styrene polymer 
bit-pieces are mixed in an aqueous solution with a quantity of the 
aliphatic impregnant sufficient to provide the desired extent of 
impregnation and a quantity of a compatible water-soluble emulsifying 
agent sufficient to emulsify the quantity of aliphatic impregnant in the 
aqueous solution. The patent teaches that suitable emulsifying agents may 
be any of the neutral soaps or synthetic wetting or dispersing agents such 
as are used as emulsifying agents in emulsion polymerization of styrene or 
any monomers used in preparing a styrenepolymer. Among these applicable 
emulsifying agents are sodium or potassium salts of fatty acids, anionic 
wetting agents such as sodium dodecyl sulfate, and cationic emulsifying 
agents such as quaternary ammonium salts. 
It is, therefore, a primary object of the present invention to provide 
methods of making antistatic expandable and expanded vinylaromatic 
polymer-containing articles with significantly decreased propensity for 
acquiring static electricity, especially when the articles are expanded to 
substantially the maximum amount so that they may be used for inexpensive 
packing material. 
It is also an object of the present invention to provide such methods that 
(1) are not deleterious to components in the articles, (2) provide a 
durable and uniform treatment, (3) are less costly in terms of materials 
and labor, (4) are easy to perform, and (5) avoid nucleation during 
extrusion of the unexpanded articles. 
It is yet another object of the present invention to provide methods which 
provide good antistatic qualities to expanded vinylaromatic 
polymer-containing articles. One indication of good antistatic quality is 
when the expanded articles dissipate an induced 5000 volt charge to 0 
volts in less than 2 seconds. It is also an object of the present 
invention to provide articles which are produced by such methods. 
SUMMARY OF THE INVENTION 
In accordance with a preferred embodiment of the invention, these and other 
objects and advantages are addressed as follows. A method of making an 
antistatic vinylaromatic polymer-containing article is disclosed which 
includes immersing an expandable vinylaromatic polymer-containing article, 
having a blowing agent dispersed therein, in a bath containing an 
ethoxylated amine compound for a length of time sufficient to allow the 
ethoxylated amine compound to penetrate into the expandable article to an 
extent such that the expandable article, when expanded to a bulk density 
of at most about 1.5 pcf (pound per cubic foot), dissipates an induced 
5000 volt charge to substantially 0 volts in less than 2 seconds. 
Antistatic expandable and expanded vinylaromatic polymer-containing 
articles using this method are also disclosed. 
DETAILED DESCRIPTION OF THE INVENTION 
The methods of this invention begin with immersing an expandable 
vinylaromatic polymer-containing article, having a blowing agent dispersed 
therein, in a bath containing an ethoxylated amine compound. The 
vinylaromatic polymer-containing articles used in this invention are 
formed of vinylaromatic polymers which are solid at room temperature. 
Vinylaromatic polymers suitable for this invention include homopolymers of 
vinylaromatic monomers, copolymers of two or more vinylaromatic monomers, 
and interpolymers of at least one vinylaromatic monomer and at least one 
nonvinylaromatic monomer which is interpolymerizable with vinylaromatic 
monomers. The preferred vinylaromatic monomers have the characteristic 
formula CH.sub.2 .dbd.CX--Ar, wherein X is hydrogen or an alkyl group 
having from 1 to 4 carbon atoms, and Ar is an aromatic radical, including 
various alkyl and halo-ring-substituted aromatic units of from 6 to 10 
carbon atoms. Representative vinylaromatic monomers include styrene, 
o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylstyrene, 
dimethylstyrene, alpha-methylstyrene, p-methoxystyrene, 
alpha-methyl-p-methylstyrene, p-isopropylstyrene, vinylnapthalene, 
acetanapthalene, vinylanthracene, indene, p-cyanostyrene and the like. 
Exemplary of nonvinyl aromatic polymers which can be polymerized with 
vinylaromatic monomers are unsaturated nitriles such as acrylonitrile, 
methylacrylonitrile, ethylacrylonitrile, and mixtures thereof. Other 
nonvinyl monomers which are copolymerizable with vinylaromatic monomers 
and which are suitable for use in the present invention are 
alpha/beta-unsaturated monobasic acids and derivatives thereof, such as 
acrylic acid, methacrylic acid, ethylacrylate, butylacrylate, 
2-ethylhexylacrylate, methylmethacrylate, methacrylate, acrylamide, 
methacrylamide, maleic anhydride, N-phenylmaleimide, dimethylmaleate, 
diethylmaleate, dibutylmaleate, the corresponding fumarates and the like. 
Other suitable nonvinyl monomers include butadiene. 
The vinylaromatic polymers may also include alloys which are a mixture of 
the aforementioned homopolymers, copolymers, and/or interpolymers 
optionally with a compatible polymer which contains none or a low amount 
of polymerized vinylaromatic monomer. These mixtures may be melt or 
pressure mixtures. 
Currently, it is preferred that the vinylaromatic polymer, including the 
alloys, contain at least 50 weight % of at least one polymerized 
vinylaromatic monomer, with the balance being polymerized nonvinylaromatic 
monomer. It is more preferred that the vinylaromatic polymers contain at 
least 50 weight percent polymerized styrene monomer, with the balance 
being other polymerized vinylaromatic monomers and/or polymerized 
nonvinylaromatic monomers. 
The shape and size of the vinylaromatic polymer-containing articles are not 
critical to the invention. The articles may be made, e.g., by (1) cutting 
extruded polymer in small lengths, (2) suspension polymerization, or (3) 
molding vinylaromatic polymer material. Examples of suitable shapes are 
cylindrical, flat, and "S"-shapes. Typical articles used for this 
invention are cylindrical and sized about 1/4 inch in length and 1/8 inch 
in diameter, i.e., a volume of about 0.003 cubic inches. Although smaller 
articles may be used in the invention, articles of about this size are 
preferred because they are easier to separate from the bath. 
The vinylaromatic polymer-containing articles used in this invention 
contain a blowing agent dispersed therein. Blowing agents are typically 
liquid aliphatic impregnants which volatilize at a temperature below the 
polymers softening point and which are non-solvents for the polymer. The 
blowing agent may account for as much as about 15 weight % of the 
vinylaromatic polymer-containing article. Aliphatic impregnants include 
hydrocarbons and/or a halogenated hydrocarbons, such as hydrogenated 
chlorofluorohydrocarbons ("CFC's"). The hydrocarbons and halogenated 
hydrocarbons include those compounds having from 4 to 6 carbon atoms, such 
as in butane, pentane, cyclopentane, hexane, and cyclohexane. 
To disperse a blowing agent in the vinylaromatic polymer-containing 
articles, basically the blowing agent may be infused in the 
vinylaromatic-containing material when molten. More specifically, the 
vinylaromatic polymer, the blowing agent, and other additives, which are 
usually used in less than one weight percent of the entire composition, 
are added to an extruder. The ingredients are melted and blended together 
in the extruder and forced out of the extruder die, cooled, for example, 
in a water bath, and cut. Examples of additives which may be used in the 
vinylaromatic polymer composition include additives such as fire 
retardants (e.g., hexabromocyclododecane or 
monopentabromochlorocyclohexane), lubricants (e.g., barium stearate, zinc 
stearate, or calcium stearate), sodium bicarbonate). Sources which 
describe techniques for incorporating the blowing agent into polymeric 
materials include U.S. Pat. Nos. 4,018,946 and 2,983,692 and the book, 
"Practical Polymerization of Polystyrene" by Bishop, published by Cahners 
(1971), which sources are hereby incorporated by reference. 
To perform the method of the present invention, the vinylaromatic 
polymer-containing articles are immersed in a bath containing an 
ethoxylated amine compound. Preferably, the ethoxylated amine compound is 
suspended in a liquid medium, e.g., water. The ethoxylated amine compound 
is preferably suspended in an amount from about 0.7 to about 3 weight 
percent based on the weight of the bath. Amounts greater than about 3 
weight percent are as effective, but are generally unnecessary. The types 
of ethoxylated amine compounds which are suitable for this invention 
include diethoxylated alkylamines, diethoxylated alkenylamines and 
mixtures thereof. Specific diethoxylated amines include diethoxylated 
tallow amine, diethoxylated coco amine, diethoxylated soya amine, and 
diethoxylated oleyl amine. 
The temperature of the bath is typically from about 23.degree. C. to about 
70.degree. C., and preferably from about 55.degree. C. to about 65.degree. 
C. If the bath is maintained at a temperature above room temperature, the 
expandable articles will often soften when immersed. The bath is 
preferably agitated throughout the immersion step to enhance the contact 
of the ethoxylated amine compound with the expandable article. It is 
desirable that the ratio of the weight of the bath to the expandable 
articles be at least about 7.5:1. One procedure for preparing the bath and 
immersing the expandable articles therein includes: (1) mixing the 
ethoxylated amine compound in the diluting liquid medium to form a uniform 
suspension, (2) heating the suspension to the desired temperature, while 
maintaining agitation, (3) placing the expandable articles in the 
suspension while maintaining the elevated temperature and agitation, and 
(4), after the desired length of time of immersion, removing the 
expandable articles from the suspension. 
The expandable articles are immersed long enough to allow the ethoxylated 
amine compound to penetrate into and affix to the expandable article. By 
immersing the expandable articles for an extended length of time, the 
ethoxylated amine compound does not merely coat the expandable articles, 
but penetrates into the articles. When the treated expandable articles are 
thereafter expanded, it has been found that the ethoxylated amine compound 
continues to be detectable on much of the surface of the expanded 
articles. Generally, the expandable articles are immersed for a length of 
time sufficient to allow the ethoxylated amine compound to penetrate into 
the expandable article to an extent such that the expandable article, when 
expanded to a bulk density of at most about 1.5 pcf (pounds per cubic 
foot), dissipates an induced 5000 volt charge to substantially 0 volts in 
less than 2 seconds. Preferably, this level of dissipation occurs when the 
expandable article is expanded to a bulk density of at most about 1.0 pcf, 
and more preferably about 0.3 pcf. The expandable article, expanded to a 
bulk density of at most about 1.5 pcf, will desirably contain at least 
about 0.2, and more desirably, about 0.6 weight percent ethoxylated amine 
compound based on the weight of the expanded article in order to achieve 
such dissipation qualities. The immersion time required may vary with the 
size of the expandable article. Typical immersion times are from about 
0.25 to about 3 hours, and more typically from about 0.5 to about 1.5 
hours. 
After the expandable articles have been immersed for a suitable length of 
they are removed from the bath and preferably dried. The drying is 
optional but substantially complete drying is preferred so that the 
expandable articles flow more easily. The drying may be completed, e.g., 
by simple air-drying or by circulating warm air around the treated 
expandable articles. 
Once the expandable articles are removed from the bath and dried, if 
desired, the expandable articles are expanded to a bulk density of at most 
about 1.5 pcf. Additional expansions further decrease the bulk density of 
the expandable articles. The expansions may be done by exposing the 
expandable articles to atmospheric steam. 
The expanded articles of this invention may be used as loose-fill packing 
material. The expandable articles may be used, for example, to make items 
such as cups and containers. Methods of making such cups and containers 
are well known in the art. 
Thus, there is provided, in accordance with the present invention, methods 
of making antistatic expandable and expanded vinylaromatic 
polymer-containing articles, which methods (1) do not deleteriously effect 
components in the articles, (2) provide durable, uniform, and efficacious 
treatments, (3) are less costly than prior art methods, (4) are easy to 
perform, and (5) do not cause nucleation during extrusion of the 
unexpanded articles. Also provided in accordance with the invention are 
expandable and expanded vinylaromatic polymer-containing articles with 
good antistatic qualities.

The following examples are illustrative only and should not be construed as 
limiting the invention which is properly delineated in the appended 
claims. 
In the following examples, the electrostatic properties of the materials 
were tested by a method modeled after the Federal Test Method (FTM) 
Standard 101C. The test determined the electrostatic properties of 
materials conditioned at less than 15% relative humidity by measuring the 
time required for complete dissipation of an induced charge. Electrostatic 
properties are defined as the ability of a material, when grounded, to 
dissipate a charge induced on the surface of the material. The difference 
between FTM 101C and the tests employed in these examples, is that the 
present examples tested the electrostatic property on pellets rather than 
on a sheet or a film. Other conditions of testing are discussed 
hereinbelow with reference to the specific examples. 
The expandable vinylaromatic polymer-containing articles used in the 
examples were formed from a non-expanded material containing: (1) about 88 
weight % polystyrene, (2) about 11 weight % blowing agent selected from 
pentane, CFC (chlorofluorohyirocarbon) 11, or mixtures thereof, and (3) 
less than or equal to about 1 weight % additives. The articles were in the 
shape of pellets which were slightly "S"-shaped having a diameter of about 
1/8" and a length of about 1/4". 
EXAMPLES 
Example 1 
187.5 grams of Sherex "VARSTAT" K22 were added to 2312.5 grams of water in 
a 4000 ml beaker. "VARSTAT" K22 is an ethoxylated coco amine available 
from Sherex Chemical Company, Inc., Dublin, Ohio. The beaker was placed on 
a hot plate, and the materials were stirred and heated to about 65.degree. 
C. 40 grams of expandable polystyrene pellets were placed in a small pouch 
made of #12 screening material, which has 1.68 millimeter openings. The 
pouch was immersed in the 65.degree. C. bath and the temperature and 
agitation was maintained. After 45 minutes, the pouch was removed and the 
treated expandable polystyrene pellets were laid out to dry on paper 
towels. After 24 hours, the dried, treated, expandable polystyrene pellets 
were expanded by exposing the pellets to atmospheric steam for 2 minutes. 
After a 24-hour resting period at room temperature, the expansion was 
repeated using the expanded pellets. The twice-expanded pellets were 
expanded a third time using the same procedure. The thrice-expanded 
pellets had strong antistatic qualities as they dissipated an induced 5000 
volt charge to 0 volts in less than 2 seconds using the test described 
above. 
Examples 2 through 12 
These examples used a water bath containing "VARSTAT" K-22 (described in 
Example 1) and varied the suspension concentration, the immersion time, 
and the water bath temperature. Table 1 provides the concentration of the 
ethoxylated amine in the bath, the immersion time, and the bath 
temperature for each example. 
TABLE 1 
______________________________________ 
Concentration.sup.a 
Immersion Bath 
Example in bath time Temp. 
# (wt %) (min.) (.degree.C.) 
______________________________________ 
2 4.5 97.5 45 
3 3 15 24 
4 3 180 24 
5 3 15 66 
6 3 180 66 
7 4.5 97.5 45 
8 6 15 24 
9 6 180 24 
10 6 15 66 
11 6 180 66 
12 4.5 97.5 45 
______________________________________ 
.sup.a concentration of diethyoxylated coco amine in water bath. 
For the examples with 3 weight % concentration suspensions, 75 grams of the 
diethoxlated coco amine were mixed in 2425 grams of distilled water for 
the examples with 4.5 weight % concentration suspensions, 112.5 grams of 
diethoxylated coco amine were mixed into 2387.5 grams of distilled water. 
For the examples with 6 weight % concentration suspensions, 150 grams of 
diethoxylated coco amine were mixed in 2350 grams of distilled water. Only 
one 3 weight % and one 6 weight % concentration suspension was made and 
re-used for the appropriate examples. With the 4.5 weight % concentration 
suspension, a new 2500 gram bath was generated for each appropriate 
example. 
For examples 2 through 12, the suspensions were placed on a hot plate and 
agitated with a stir bar. Expandable polystyrene pellets were placed in 
screen pouches and immersed in the suspensions for the time specified in 
Table 1. After the specified immersion time, the treated expandable 
polystyrene pellets were placed immediately on a paper towel to dry. The 
pellets were dried for 24 hours in ambient conditions. Examples 5 and 6 
were run after the bath temperature had reached 81.degree. C. overnight 
and returned to 66.degree. during treatment. 
The treated expandable polystyrene pellets were then expanded with 
atmospheric steam for 2 minutes. The bulk densities of the once-expanded 
polystyrene pellets were measured and ranged from 0.95 to 1.00 pcf. The 
expanded polystyrene pellets were then aged or rested for 48 hours at 
78.degree. F. with a relative humidity of 9% and were then tested for 
electrostatic dissipation. Table 2 provides the bulk density of each of 
the Examples 2 through 12 and the average decay times in seconds, both 
from a positive 5000 volt charge as well as from a negative 5000 volt 
charge. All of the Examples 2 through 12 dissipated a 5000 volt charge in 
less than 2 seconds. 
TABLE 2 
______________________________________ 
Bulk Avg. Decay Avg. Decay 
Example Density Time.sup.a From 
Time.sup.a From 
# (pcf) +5000 V (sec) 
-5000 V (sec) 
______________________________________ 
2 0.95 0.09 0.09 
3 0.97 0.80 0.86 
4 0.95 1.32 1.42 
5 1.00 0.10 0.13 
6 0.95 0.11 0.11 
7 0.98 0.09 0.10 
8 0.99 0.10 0.10 
9 0.98 0.07 0.07 
10 0.98 0.08 0.09 
11 0.99 0.08 0.08 
12 1.00 0.14 0.14 
______________________________________ 
.sup.a average determined from three measurements 
The once-expanded polystyrene pelles were then expanded again with 
atmospheric steam and aged for about 48 hours at 78.degree. F. with a 
relative humidity of 9.2%. The bulk density of the once-expanded pellets, 
the average decay time from +5000 volts and the average decay time from 
-5000 volts are provided in Table 3. 
TABLE 3 
______________________________________ 
Bulk Avg. Decay Avg. Decay 
Example Density Time.sup.a From 
Time.sup.a From 
# (pcf) +5000 V (sec) 
-5000 V (sec) 
______________________________________ 
2 0.47 0.21 0.22 
3 0.46 .sup. 30+.sup.b 
30+ 
4 0.44 30+ 30+ 
5 0.51 0.64 0.69 
6 0.48 0.45 0.42 
7 0.49 0.25 0.26 
8 0.49 0.55 0.59 
9 0.50 0.19 0.20 
10 0.47 0.43 0.64 
11 0.50 0.23 0.24 
12 0.49 0.65 0.68 
______________________________________ 
.sup.a average determined from three measurements 
.sup.b greater than 30 seconds 
The twice-expanded polystyrene pellets were then expanded yet again using 
atmospheric steam and aged for 96 hours at 79.degree. F. with a relative 
humidity of 9.8%. The thrice-expanded polystyrene pellets were then tested 
for charge dissipation. The bulk densities, the average decay times from 
+5000 volts and the average decay times from -5000 volts are given in 
Table 4 for the thrice-expanded polystyrene pellets. 
TABLE 4 
______________________________________ 
Bulk Avg. Decay Avg. Decay 
Example Density Time.sup.a From 
Time.sup.a From 
# (pcf) +5000 V (sec) 
-5000 V (sec) 
______________________________________ 
2 0.28 0.23 0.30 
3 ND.sup.b .sup. 30+.sup.c 
30+ 
4 ND.sup. 30+ 30+ 
5 0.32 1.02 1.27 
6 0.33 0.39 0.38 
7 0.29 0.29 0.28 
8 0.28 0.33 0.36 
9 0.31 0.20 0.22 
10 0.30 0.44 0.44 
11 0.33 0.26 0.29 
12 0.31 3.06 3.83 
______________________________________ 
.sup.a average determined from three measurements 
.sup.b not determined 
.sup.c greater than 30 seconds 
Examples 13 through 18 
For examples 13-18, the procedure as described for Examples 2 through 12 
was repeated with the following differences. Examples 13-18 employed 
"KEMAMINE" AS 989, an ethoxlated tallow amine, as the ethoxylated amine 
compound and varied the suspension concentration and the immersion time. 
"KEMAMINE" is a trademark of the Witco Chemical Corporation, New York, 
N.Y. For each of Examples 13 through 18, a new water bath suspension was 
prepared, based on a total bath weight of 800 grams. The bath temperature 
was maintained at 60.degree. C. For each example, 75 grams of the 
expandable polystyrene pellets were immersed in the water bath suspension. 
For these examples, a THERMOMIX 441 heater-circulator, Type 850123, from 
B. Braun, W. Germany and a 1000 ml beaker constituted the apparati. The 
various bath concentrations and immersion times are provided in Table 5 
for each example. After treatment and drying, the expandable polystyrene 
pellets were expanded three times using atmospheric steam. For each 
example, the bulk densities of the expanded polystyrene pellets were 
measured. Results after one expansion are provided in Table 6, the results 
after two expansions are provided in Table 7, and the results after three 
expansions are provided in Table 8. Tests on the once-expanded and 
twice-expanded pellets were conducted after 24 hours of aging at 
conditions of 9.5% relative humidity and about 78.degree. F. Tests on the 
thrice-expanded pellets were conducted after 48 hours of aging at 
conditions of less than 15% relative humidity and about 78.degree. F. 
TABLE 5 
______________________________________ 
Concentration.sup.a 
Immersion 
Example In Bath Time 
# (wt %) (min.) 
______________________________________ 
13 2.75 72.5 
14 4.5 100 
15 1.0 45 
16 2.75 72.5 
17 1.0 100 
18 4.5 45 
______________________________________ 
.sup.a concentration of diethoxylated tallow amine in water bath 
TABLE 6 
______________________________________ 
Bulk Avg. Decay 
Example Density Time.sup.a From 
# (pcf) + and -5000 V (sec) 
______________________________________ 
13 0.97 0.37 
14 0.99 0.49 
15 0.95 0.33 
16 0.97 0.55 
17 0.97 0.65 
18 0.96 0.44 
______________________________________ 
.sup.a Average of three measurements from +5000 V and three measurements 
from -5000 V 
TABLE 7 
______________________________________ 
Bulk Avg. Decay 
Example Density Time.sup.a From 
# (pcf) + and -5000 V (sec) 
______________________________________ 
13 0.48 0.49 
14 0.50 0.62 
15 0.48 0.45 
16 0.49 0.78 
17 0.48 0.41 
18 0.50 0.55 
______________________________________ 
.sup.a Average of three measurements from +5000 V and three measurements 
form -5000 V 
TABLE 8 
______________________________________ 
Bulk Avg. Decay 
Example Density Time.sup.a From 
# (pcf) + and -5000 V (sec) 
______________________________________ 
13 0.28 0.23 
14 0.29 0.18 
15 0.29 0.17 
16 0.28 0.22 
17 0.28 0.46 
18 0.29 0.19 
______________________________________ 
.sup.a Average of three measurements from +5000 V and three measurements 
from -5000 V 
Example 19 
Unexpanded polystyrene pellets were treated with the previously-described 
ethoxylated tallow amine, "KEMAMINE" AS 989, according to the invention. 
Eight sets of treated pellets were prepared. Four of the eight sets were 
expanded with atmospheric steam once. A sample of the once-expanded 
pellets had an average static decay time of 0.15 seconds, averaged from 
three decay times measured from +5000 volts and three decay times measured 
from -5000 volts. The level of ethoxylated tallow amine in the 
once-expanded pellets was measured by gas chromatography in four separate 
samples. Results indicated levels of ethoxylated tallow amine of 0.30, 
0.40, 0.31, and 0.31 weight % based on the weight of the expanded pellets. 
The other four of the eight sets were expanded with atmospheric steam three 
times. A sample of the thrice-expanded pellets had an average static decay 
time of 0.21 seconds, averaged from three decay times measured from +5000 
volts and three decay times from -5000 volts. The level of ethoxylated 
tallow amine in the thrice-expanded pellets was measured by gas 
chromatography in four separate samples. Results indicated levels of 
ethoxylated tallow amine of 0.24, 0.26, 0.39, and 0.34 weight % based on 
the weight of the expanded pellets. 
Examples 20-21 
Unexpanded polystyrene pellets were treated by immersing the pellets in a 
water bath containing 4.5 weight % of the previously-described 
ethoxylated coco amine, "VARSTAT" K22. Two sets of the treated polystyrene 
pellets were expanded three times. Table 9 provides the bulk densities, 
the average static decay times, and the average weight % ethoxylated coco 
amine in the expanded pellets determined by gas chromatography. 
TABLE 9 
______________________________________ 
Bulk 
Example Density Avg. Decay Avg. Weight % 
# (pcf) Time (sec) Amine Compound.sup.a 
______________________________________ 
20 0.25 0.68.sup.b 0.68 
21 0.33 0.20.sup.c 0.68 
______________________________________ 
.sup.a average of two measurements 
.sup.b average of nine decay times from -5000 volts and nine decay times 
from +5000 volts 
.sup.c average of three decay times from -5000 volts and three decay time 
from +5000 volts 
While my invention has been described in terms of a specific embodiment, it 
must be appreciated that other embodiments could readily be adapted by one 
skilled in the art. Accordingly, the scope of my invention is to be 
limited only by the following claims.