Solid antistatic compositions

A concentrated antistatic composition adapted for incorporation into various polymers such as olefins is prepared by admixing a liquid ethoxylated amine antistatic agent, such as an N,N-bis-(2-hydroxyethyl) alkenyl or mixed alkenyl and alkyl (C.sub.6 -C.sub.18)amine, with various polymers such as, for example, polypropylene, 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 simply and readily blended into a polymer such as polyethylene as a dry, solid product to impart antistatic properties to the blended resin.

DESCRIPTION OF THE INVENTION 
The present invention relates to polymeric materials, and, more 
particularly, to novel solid antistatic agents for incorporation into such 
polymeric materials and to a process for making such novel antistatic 
agents. 
It has long been known that various polymers tend to collect electrostatic 
charges on their surface. This tendency creates difficulty in the handling 
of the polymers and of articles made therefrom, for it occurs during 
storage, as well as in the course of processing the polymers into shaped 
forms, such as filaments, sheets, films, and molded plastics. 
Such electrostatic charges cause dust and dirt particles to adhere to the 
plastic surfaces and, also, the plastic surfaces to adhere to each other 
or to the equipment used in processing. Under certain circumstances, the 
accumulated charges may give rise to sparks, with an attendant fire 
hazard. The tendency toward the building of electrostatic charges is 
especially marked in the case of polymers and copolymers made from 
ethylenically unsaturated monomers, such as polymers and copolymers of 
vinyl chloride, vinylidene chloride, styrene, and the various polyolefins, 
such as polyethylene, polypropylene, and polybutylene. These are referred 
to herein as olefinic polymers. 
Among the approaches taken in the prior art to reduce the tendency of 
plastic materials toward electrostatic charging has been either to coat 
the plastic material with an antistatic composition, or to incorporate it 
into the body of the plastic material. The latter expedient is generally 
considered to be more effective. Compounds which have been proposed for 
this purpose include polyalkylene glycols and their esters and ethers, and 
a wide variety of amines and amides. 
Thus, for example, it has been proposed to incorporate into an olefinic 
polymer such as polyethylene, during compounding, molding or fabrication, 
as an antistatic additive, a small amount of at least one 
N,N-(hydroxyalkyl)-alkylamine, and a process of this type is disclosed in 
U.S. Pat. No. 3,631,162. 
It is also known to incorporate into polyolefins, such as polyethylene 
film, a material which functions as a slip agent, by migrating to the 
surface in sufficient quantity to provide thereon a thin film which 
functions as a lubricant. Long chain aliphatic amides are usually employed 
for this purpose, and a system of this type is disclosed in, for example, 
U.S. Pat. No. 3,467,706. 
Many of the amine or amide antistatic agents are liquids which, when 
incorporated into the resin compositions, migrate to the surface at an 
undesirably rapid rate, causing losses by evaporation, diminished 
antistatic effectiveness, development of undesirable odors, and adversely 
affecting the surface properties of the plastic, for example by promoting 
cracking or crazing. For example, it was stated in the above-mentioned 
U.S. Pat. No. 3,631,162 (Table III, Footnote 4) that, at 8 parts of 
N,N-bis-(2-hydroxyethyl) alkylamine in 1000 parts of polyethylene, large 
amounts of the antistatic agent exuded to the surface. Previous attempts 
to incorporate a high percentage, i.e. greater than about 10%, of a liquid 
antistatic agent into polymers have been limited by the room temperature 
solubility of the antistatic agent in the polymer. That is, when the 
solubility in the polymer is exceeded, as by cooling a solution at high 
temperatures, two phases will be formed, namely, a liquid phase containing 
some dissolved polymer and a solid phase containing some dissolved liquid. 
It is accordingly an object of the present invention to provide solid 
antistatic agents which incorporate normally liquid amine antistatic 
compounds. 
A further object lies in the provision of solid antistatic agents capable 
of being added to various polymeric materials in amounts in excess of 
those achieved using liquid antistatic agents. 
Yet another object of this invention is to provide an economical process 
for forming such solid antistatic agents. 
Other objects and advantages of the present invention will be apparent as 
the following description proceeds. 
While the invention is susceptible of various modifications and alternative 
forms, specific embodiments thereof have been shown by way of example and 
will be hereinafter described in detail. It should be understood, however, 
that it is not intended to limit the invention to the particular forms 
disclosed, but, on the contrary, the intention is to cover all 
modifications, equivalents and alternatives falling within the spirit and 
scope of the invention as expressed in the appended claims. 
In brief, the present invention is predicated on the discovery that, by 
appropriate processing steps, certain normally liquid amine antistatic 
agents can be converted into novel antistatic agents which behave as 
solids. Such novel antistatic agents then possess the advantageous 
characteristics of antistatic agents wherein the active material is itself 
normally solid. 
More particularly, and in accordance with a principal aspect of the present 
invention, it has been found that certain liquid amine antistatic agents 
can be converted into solid form, suitable for incorporation into a 
polymer, by admixing the amine with a suitable resin carrier such as, for 
example, polypropylene, heating the thus-formed mixture to a temperature 
above the softening temperature of the resin used as the carrier such that 
a homogeneous liquid is formed, and then rapidly cooling the liquid to 
form a solid homogeneous mass. It has been found that adequate cooling is 
achieved when the liquid mixture becomes completely solid within a period 
of time between about 1/2 sec. to about 10 minutes, depending upon the 
quantity of liquid involved and the cooling means employed. 
In practice, it has been found that the rate of cooling can be controlled 
so as to obtain the desired results in at least two ways. In the first, a 
metal plate at ambient temperature (25.degree. C.) is used as a heat sink, 
and will extract heat from the material at a sufficient rate if the 
homogeneous solution is poured rapidly onto the plate in a thin layer. 
Best results have been achieved with layers less than 1/4 inch thick, but 
similar results are observed where layers up to about 1/2 inch or so 
thickness are obtained. 
In the second method, a rapid cooling rate is achieved by pouring the 
solution of the liquid resin carrier and antistatic agent into a 
relatively large amount of an inert liquid such as water at a temperature 
from 0.degree. C. to 75.degree. C. The preferred temperature range is from 
60.degree. C. to 75.degree. C. since lower temperatures cause significant 
amounts of water to be trapped in the globules which can, however, be 
removed by drying in a vacuum. Globules of a solid combination of 
antistatic agent and the resin carrier having a diameter of 1/8 to 1/16 
inches are obtained which are not wet to the touch. 
It might have been expected that, upon cooling, a liquid phase of the amine 
would separate containing some dissolved resin, especially when the normal 
solubility of the amine in the resin employed as the carrier is exceeded. 
It has been observed, for example, that if the hot homogeneous mixture of 
resin carrier and liquid antistatic agent is stirred continuously while 
the mixture cools, the mixture does not cool to a homogeneous solid, but 
two visually discernible phases result. However, with rapid cooling of the 
hot homogeneous mixture of antistatic agent and resin carrier according to 
the invention, no visually discernible phase separation occurs. This 
unexpected behavior takes place even where it is known that, for example, 
merely by mixing, not more than about 10% by weight of antistatic agent 
could be incorporated when polypropylene is used as the resin carrier 
without the separation of a visually discernible liquid phase. Thus, such 
resulting antistatic agent-polypropylene composition contains much more of 
the antistatic agent than would be expected from room temperature 
solubility considerations alone. 
With respect to the antistatic constituent, any normally liquid (i.e.--at 
ambient temperatures) antistatic agent may be employed which is capable of 
blending homogeneously with a resin carrier at elevated temperatures and 
forms a solid material upon cooling without the presence of a visually 
discernible phase separation. Still further, such antistatic agents should 
not significantly degrade upon heating to the temperatures required to 
render the mixture of the resin carrier and antistatic homogeneous. 
In accordance with a preferred embodiment of the present invention, 
normally liquid ethoxylated aliphatic amines are employed which are 
derived from alkyl, primary alkenyl or mixed alkenyl and alkyl amines in 
which the alkenyl and alkyl moiety each have a chain length of between 
about 6 and 18 carbon atoms. 
Particularly preferred amine antistatic agents are N,N-bis-(2-hydroxyethyl) 
alkenyl or mixtures of alkenyl and alkyl (C.sub.12 -C.sub.18) amines which 
are liquid at ambient temperatures. Such amines are obtained from 
distilled coco, soya, oleyl or tallow, or mixtures thereof. Examples of 
these amines are diethoxylated tallow (mixed alkenyl and alkyl) amine, and 
diethoxylated coco amine, which are marketed under the designations 
Armostat 310 and Armostat 410, respectively, by Armak Company, Chicago, 
Ill. 
Considering the chain length of the alkenyl and alkyl moiety of the 
preferred ethoxylated aliphatic amines, the ability to form a satisfactory 
solid antistatic agent diminishes when the chain length is less than 
C.sub.8. A chain length of C.sub.6 represents the demarcation between an 
acceptable and unacceptable product. Chain lengths in excess of C.sub.18 
(e.g. up to C.sub.22 or more) can conceptually be utilized; however, 
amines with such chain lengths are typically normally solid so that, for 
most purposes, incorporation in the solid antistatic agents of the present 
invention will not yield any significant benefits. In addition, from the 
functional standpoint, chain lengths of C.sub.12 to C.sub.18 have been 
found to provide the most effective antistatic properties. 
If desired, mixtures of useful normally liquid antistatic agents can also 
be employed. Of course, when mixtures are employed, the particular mixture 
should be capable of being processed with a resin carrier to form the 
novel antistatic agents in accordance with the present invention as is 
described herein. 
The type of resin used as the carrier for the normally liquid antistatic 
agent may be varied within wide limits. From the functional standpoint, 
any resin may be employed which will form a homogeneous liquid with the 
antistatic agent at elevated temperatures and thereafter, upon cooling, 
forms a solid material, as has been described herein. 
Representative examples of suitable carriers include polyolefins such as 
high and low density polyethylene, polypropylene and polystyrene. In 
addition, polyaryl ethers such as polyphenylene oxide, 
styreneacrylonitrile copolymers, acrylic acid copolymers such as 
ethyleneacrylic acid and styrene-butadiene rubbers may also be suitably 
used. 
It should also be appreciated that, if desired, mixtures of resins may be 
employed and that copolymers as well as homopolymers can be utilized. For 
example, in addition to using polyethylene and polypropylene homopolymers, 
ethylene-propylene copolymers are useful. Still further, the resin carrier 
can suitably comprise a mixture of a useful resin such as polyphenylene 
oxide blended with minor amounts of a resin that, by itself, could not be 
utilized, such as a polycarbonate. The utility of a particular resin 
mixture or copolymer can be readily determined as has been described 
herein. Thus, to be useful, the particular carrier must be capable of 
forming a homogeneous solution at elevated materials with the particular 
antistatic agent being employed as well as forming, after cooling, a solid 
material with no visually discernible liquid phase. 
With respect to relative amounts of the constituents, the normally liquid 
antistatic agent utilized can be present in an amount of from about 10 to 
about 90%, based upon the total weight of the resin and antistatic agent. 
While amounts less than about 10% may be employed, the advantages of the 
present invention are substantially lessened since such amounts can be 
achieved by normal extrusion techniques. Similarly, amounts up to perhaps 
95% by weight or so might be useful in certain situations. However, the 
solid antistatic agent formed at such concentrations is relatively weak; 
and liquid will often exude out of the material when placed under 
load-bearing conditions such as commercial sized containers. Due to 
economical and processing considerations, it is preferred to maintain the 
liquid antistatic agent content in the range of from 50 to 75%. 
While the factors which determine whether a solid material is formed are 
not fully understood, certain useful observations can be made. For 
example, when polypropylene is used as the resin carrier, it has generally 
been found to increase the rapidity of the cooling as the amount of 
normally liquid antistatic agent is increased. Further, other factors 
which must be taken into consideration include the initial viscosity of 
the homogeneous solution at the elevated temperature being used and the 
rate at which the viscosity builds up as the homogeneous solution is being 
cooled. Still further, the initial temperature at which the homogeneous 
solution is formed and the .DELTA.T between that temperature and the 
temperature of the cooling medium must also be taken into account. 
It can, in general, be observed that the range of useful cooling rates may 
be expanded by appropriate consideration of the parameters set forth 
herein. Thus, a wider range of cooling rates may, in general, be utilized 
with increasing resin contents, higher initial viscosities (influenced, of 
course, by the temperature at which a homogeneous solution is formed) and 
the magnitude of the .DELTA.T. More rapid viscosity buildups will also 
likely increase the range of useful cooling rates. 
The solid antistatic agent product of the present invention, as has been 
described herein, comprises a solid material with no visually discernible 
liquid phase. Typically, the product will be dry to the touch. However, it 
is believed that the normally liquid antistatic employed retains its 
liquid character in the product but is masked by the polymer carrier so as 
to give the appearance of a solid material together with allowing the 
product to be used in the fashion as would a true solid, with the 
attendant advantages. 
It should be appreciated that the solid product of the present invention, 
while generally visually solid after cooling, may in certain situations 
contain surface liquid. Such surface liquid can, however, be removed by 
any suitable means such as, for example, by blotting with an absorbent 
material or by a solvent rinse. The resulting product will then be a solid 
antistatic agent according to the present invention, i.e. - a solid 
material with no visually discernible liquid phase. 
With respect to the characteristics of the novel antistatic agents of this 
invention, the prime phenomena is not surface adsorption of the normally 
liquid antistatic agent on the surface of the resin carrier, i.e. - as a 
substantially continuous film or coating of the resin. In such a 
structure, the amount of liquid additive that could be tolerated would be 
dependent upon the surface area of the resin carrier. This is not the case 
in the present invention since the amount of the liquid antistatic agent 
which can be tolerated is wholly independent of the surface area of the 
resin carrier. 
The solid antistatic agents of the present invention can be further 
processed to provide any physical form that is desired. In general, the 
physical form will be dependent upon the virgin resin to which it is to be 
added to impart the desired antistatic properties. As illustrative 
examples, resin is typically commercially available as powders, pellets or 
granules. To allow optimum blending with the virgin resin, the solid 
antistatic agent of this invention is thus desirably processed into 
powder, pellet or granular form, depending upon the physical form of the 
virgin resin to which it will be added. 
The type of virgin resin will also, to some extent, determine the polymer 
which should be utilized as the carrier. Thus, if the antistatic agent is 
to be used with polyethylene resin, polyethylene is desirably employed as 
the resin carrier. Any resin can, however, be used as the carrier so long 
as it is compatible with the virgin resin and does not significantly and 
adversely affect the properties of the virgin resin. Moreover, in view of 
the relatively small amount of resin carrier which is contained in the 
solid antistatic agents of this invention, the problem of compatibility is 
minimized. 
The amount of antistatic agent which should be incorporated into the virgin 
resin is known and can be varied as desired. Amounts effective to provide 
amounts of antistatic agent in the range of about 0.05% to about 3.0% or 
so (based upon total weight) will generally be satisfactory. As is known, 
the amount utilized depends upon the type of resin being treated and the 
fabrication conditions used for forming the plastic article. The 
antistatic agents of the present invention can be added to the virgin 
resin by any desired means, dry blending or addition in an extrusion 
process being typical illustrative examples.

The following examples are intended to be merely illustrative of the 
present invention and not in limitation thereof: 
EXAMPLE 1 
A mixture of 50% by weight of N,N-bis-(2-hydroxyethyl) - tallow amine 
(Armostat 310) and 50% by weight of polypropylene pellets (melt flow index 
- 8.0) is heated with stirring at 180.degree. C. until a clear homogeneous 
liquid is obtained. The liquid is then cooled rapidly, within a period of 
about 10 minutes, to room temperature, whereupon it forms a dry solid 
mass. The mass is ground to a dry powder and incorporated into molten 
polyethylene resin at a temperature of about 185.degree. C. in an amount 
equivalent to 0.15% of amine and 0.15% of polypropylene respectively, by 
weight. 
A polyethylene product exhibits antistatic and increased slip properties. A 
sample aged for 6 days, when charged to 800 volts was found to discharge 
to zero volts within 45 seconds, as compared with a control sample of 
untreated polyethylene which retained its charge indefinitely. 
______________________________________ 
Static coefficients of friction were as follows: 
Control sample with no additive 
0.70 
Sample with amine alone (at 0.1%) 
0.50 
Sample with amine and polypropylene 
(each at 0.15%) 0.36 
______________________________________ 
EXAMPLE 2 
The same procedure was followed as in Example 1, except that the proportion 
of the amine of Example 1 incorporated into the polypropylene was 75% by 
weight. The solid material was ground and incorporated into polyethylene 
in the same proportions as to the amine component as in Example 1, i.e. 
0.15% amine and 0.05% polypropylene and evaluated for antistatic and slip 
properties with the following results: a sample aged for five days when 
charged to 800 volts was found to discharge to zero volts in 18 seconds. 
Static coefficient of friction on this sample was found to be 0.51. 
EXAMPLE 3 
Following the same procedure as in Example 2, 75% by weight of the amine of 
Example 2 was incorporated into polystyrene (crystal grade and having a 
melt flow index of 4.5). In this instance, the temperature was raised to 
240.degree. C. to dissolve the beads of polystyrene. Stirring was 
continued for about five minutes after complete solution took place. Then 
about 1 cc. was poured to a depth of about 1/16 inches on to a flat metal 
plate and chilled rapidly, i.e. in about five minutes, to give a brittle, 
dry material. A sample of about 50 cc. was poured into a flat dish to a 
depth of about 1/2 inches and upon cooling it became hard, but was 
slightly wet on the top and bottom. A third sample was allowed to remain 
in the beaker to a depth of about 11/2 inches and was cooled by standing. 
The third portion separated into a liquid and a solid phase. 
The dry, brittle antistatic concentrate prepared above can be incorporated 
into an olefinic polymer, for example, molten polystyrene resin, by adding 
ground concentrate in an amount equivalent to 3% of amine by weight and 
cooling. The antistatic and slip properties of this material are 
determined in the same manner as in Example 1. 
Additional samples of the above were made varying the percentages of amine 
incorporated in the polystyrene and cooling by pouring the dissolved 
material into water at various temperatures as indicated in Table I and 
then placing the samples in a manila envelope. 
TABLE I 
______________________________________ 
Percentage 
Temp. of Temp. of Sol. 
of Amine: 
Water at Time Poured 
Characteristics of 
Polystyrene 
(.degree.C.) 
(.degree.C.) 
Product 
______________________________________ 
80:20 0 230 solid, brittle, greasy 
feel; some trapped 
H.sub.2 O 
25 230 solid, stained envelope* 
60 230 solid, stained envelope* 
75:25 0 230 solid, brittle, slightly 
greasy; some trapped 
H.sub.2 O 
25 230 solid, brittle, slightly 
stained envelope* 
60 230 solid, dry 
75 230 little trapped H.sub.2 O 
70:30 0 230 solid, brittle, dry 
25 230 solid, brittle, very 
slightly stained 
envelope* 
60 230 solid, brittle, very 
slightly stained 
envelope* 
75 230 solid, brittle, very 
slightly stained 
envelope* 
60:40 0 240 solid, dry 
25 240 solid, dry 
60 240 solid, dry 
75 240 solid, dry 
______________________________________ 
*Shows relative amounts of antistat on the surface of the solid material. 
EXAMPLE 4 
The same procedure was followed as in Example 3, except that impact grade 
polystyrene (Monsanto "Lustrex 77", melt flow index - 4.0 and density - 
1.04) was used. Impact grade polystyrene is actually a copolymer of 
styrene and butadiene. The mixture was heated with stirring to a 
temperature of 235.degree. C. and poured quickly into a chilled 
stainless-steel pan so that a film about 1/16 inches thick was formed 
which cooled in one minute. The solid material was found to be dry and 
hard, except for a small amount of condensation on the bottom. After 
standing over night, the bottom was found to be dry with no trace of 
greasiness. Another sample was dissolved at 220.degree. C. and poured on 
to a 1/64 inch stainless steel plate at room temperature (25.degree. C.) 
to cool. A hard, dry solid 5/8 inches thick was formed. 
EXAMPLE 5 
Following the same procedure as Example 1, a solid dry product was obtained 
by incorporating 75% by weight N,N-bis-(2-hydroxyethyl) coco amine 
(Armostat 410) in 25% by weight of the polypropylene identified in Example 
1. A small amount was cooled on a spatula which was dry to the touch after 
several hours. Similar antistatic and slip effects can be obtained by 
incorporating the ground product into polyethylene in an amount equivalent 
to 0.15% of amine. 
EXAMPLE 6 
A mixture of 110.6 grams of the polypropylene and 64.4 grams of the amine 
(both identified in Example 1), was stirred at 175.degree. C. to give a 
final concentration of 36.8% amine by weight. After cooling, the white, 
product was found to be solid and dry. 
EXAMPLE 7 
A run similar to Example 3 was made using the crystal grade polystyrene 
identified therein. Solution was complete at about 235.degree. C. A 
portion of the run was cooled by pouring the molten mixture into a chilled 
stainless steel pan. The material was dry and hard with only a slight 
wetness at the edges. 
Another portion of the molten material was poured into water. On cooling, 
this product was hard and dry. 
EXAMPLE 8 
Following the same procedure as in Example 1, 75% by weight of the amine of 
Example 1 was incorporated into General Electric "Noryl 731" (a blend of 
17 percent polyphenylene oxide with 69 percent high impact polystyrene, 
and minor amounts of polybutadiene and polyethylene). After stirring at 
250.degree. C. for about five minutes, the mixture was poured into flat 
dishes to cool. The product was dry and hard with no trace of greasiness. 
EXAMPLE 9 
The same procedure was followed as in Example 1, except that 75% by weight 
of the amine of Example 1 was incorporated into 25% by weight of a 
styrene-acrylonitrile copolymer (Dow Chemical "Tyril Crystal 71H"). 
Solution began to take place at 255.degree. C. and the temperature was 
then raised to 275.degree. C. to speed the solution process. One half of 
the solution was poured into a metal sheet to cool and the other half was 
poured into a flat glass dish. Both solutions cooled within about two 
minutes and formed a hard, brittle solid although some surface wetness was 
observed. 
EXAMPLE 10 
The same procedure and constituents set forth in Example 1 were used, 
except that the portion of the amine of Example 1 incorporated into the 
polypropylene was 90% by weight. The mixture was stirred vigorously while 
heating to a temperature of 200.degree. C. The solution was poured on to a 
sheet of aluminum foil to a depth of about 50 mills for quick chilling. A 
solid was obtained that was quite wet. At this proportion of amine, it 
appears that a small amount of a liquid phase is formed. While this wet 
product may be useful for some purposes (or the surface liquid phase 
removed as by blotting with an absorbent material), to obtain a completely 
dry product, either a somewhat lower proportion of amine must be used or 
cooling achieved at a faster rate. It is contemplated that a faster 
cooling rate can be achieved in the following manner: feed a metered 
amount of the heated solution on to a moving, chilled conveyer. The rate 
of cooling can be controlled by varying the feed rate of polymer so as to 
control the thickness of the material on the conveyer. The speed of the 
conveyor and the temperature of the conveyer plates can also be regulated 
to achieve different cooling rates. The conveyer plates themselves can be 
cooled with a circulating cooling medium, such as air, water, brine 
solution, Freon, etc. 
EXAMPLE 11 
Following the same procedure as in Example 5, 75% by weight of 
N,N-bis-(2-hydroxyethyl) coco amine (Armostat 410) was incorporated into 
25% by weight of crystal grade polystyrene (identified in Example 3) and 
heated with stirring to 215.degree. C. After stirring for ten minutes, the 
sample was chilled by pouring into a flat dish. A solid dry material was 
formed except for a slight wetness on the bottom and top. The solid 
material can be ground and incorporated into polyethylene in an amount 
equivalent to 0.15% amine to obtain similar antistatic slip effects. 
EXAMPLE 12 
Following the same procedure as in Example 12, 50% by weight of the amine 
of Example 11 was incorporated in 50% by weight of crystal grade 
polystyrene (identified in Example 3) at a temperature of 230.degree. C. 
and mixed for a few minutes until it became homogeneous. A sample was 
poured on to a stainless steel plate at room temperature (25.degree. C.) 
to cool in a layer about 3/16 inches thick. Another sample was cooled by 
pouring into a Petrie dish at room temperature. Both samples, when cool, 
were hard and dry. 
EXAMPLE 13 
Samples of the solid antistatic agent concentrate prepared in accordance 
with the preceding examples and containing 75% by weight of the amine of 
Example 5 and 25% polypropylene (identified in Example 1) were added to 
powdered charges of high density polyethylene in a "rotomolder" in amounts 
equivalent to 0.2% and 0.4% by weight of amine to polyethylene. 
Rotomolding equipment such as that manufactured by Roto Mold & Die 
Company, Cuyahoga Falls, Ohio, is well known and available on the market. 
In the rotomolding process, dry powdered resin is placed in a closed mold 
and rotated until the resin charge is evenly distributed around the inside 
surface thereof. The resin is then heated to its fusion temperature and 
thereafter cooled. In this example, dry, powdered solid antistatic agent 
was mixed with the resin and charged to the "rotomolder". The antistatic 
agent imparted good to excellent antistatic properties to the final molded 
product as indicated by the half-life, i.e. the time for the charge to 
decay to one-half the original value, of the samples in Table II: 
TABLE II 
______________________________________ 
Conc. of Amine Initial Charge 
Half-Life 
______________________________________ 
0.0% (control) 750 volts no decay 
0.0% (control) 750 volts no decay 
0.2% 2,000 volts 5 seconds 
0.2% 1,800 volts &lt;1 second 
0.2% 1,250 volts &lt;1/2 second 
0.4% 3,200 volts &lt;1/2 second 
0.4% 2,200 volts &lt;1/2 second 
______________________________________ 
No attempt was made to incorporate other liquid or solid antistatic agents 
since rotomolders have heretofore been unable to incorporate into 
rotomolded resins any antistatic agent which proved effective. 
EXAMPLE 14 
Additional samples of solid antistatic agent were formed using the normally 
liquid amine identified in Example 1 and various polymers as the resin 
carrier by the procedure generally described as follows. 
The amine and the polymer were mechanically stirred while the temperature 
was raised to about 230.degree. C., at which point a clear solution was 
obtained. After 20 minutes at this temperature, the solution was poured 
onto a metal plate at room temperature. A solid material was obtained, 
containing substantially the amount of the amine added. 
The polymers used and the relative amounts of the constituents are set 
forth in Table III. 
TABLE III 
______________________________________ 
Amount of Amine, % by wt., based 
Polymer on total weight of polymer and amine 
______________________________________ 
Low density polyethylene.sup.1 
75 
Low density polyethylene.sup.1 
50 
Low density polyethylene.sup.1 
95 
High density polyethylene.sup.2 
95 
High density polyethylene.sup.2 
65 
High density polyethylene.sup.2 
55 
High and low density 
polyethylene.sup.3 
75 
Polyphenylene oxide and 
polystyrene blend.sup.4 
75 
Styrene-butadiene rubber.sup.5 
75 
Ethylene-acrylic acid 
copolymer.sup.6 
75 
______________________________________ 
.sup.1 Union Carbide "DND 2004" (melt flow index 1.0, density 0.919) 
.sup.2 Union Carbide "DFD 0100" (melt flow index 2.1, density 0.922) 
.sup.3 50/50 weight mixture of Nos. 1 and 2 
.sup.4 General Electric "Noryl 31"- 
.sup.5 Shell Chemical "Kraton 1002" (density 0.92-0.94) 
.sup.6 Du Pont "Surlyn 1652" (melt flow index 4.4) 
EXAMPLE 15 
A solid antistatic agent was formed using the normally liquid amine of 
Example 1 and an ethylene-propylene copolymer (Phillips "CGH-040-02", melt 
flow index - 4.0). 
The amine and the copolymer, in amounts to provide a weight ratio of amine 
to copolymer of 75/25, based on the total weight, were heated to a 
temperature in excess of 200.degree. C. until a homogeneous solution was 
obtained; and the solution was then poured onto a metal plate at room 
temperature and allowed to cool. 
A very hard and flexible solid material was formed. 
EXAMPLE 16 
A solid antistatic agent was formed by admixing 25 grams of the 
polypropylene identified in Example 1 with 75 grams of 
N,N-bis-(2-hydroxyethyl) octylamine. 
The mixture was heated with high speed stirring. The resin formed clumps at 
160.degree. C.; at 165.degree. C., a resin mass was formed and, at 
255.degree. C., the viscosity increased. At 260.degree. C., a viscous 
homogeneous phase formed and was poured onto a metal plate at room 
temperature. 
Upon cooling, the material appeared as a strong, opaque and dry solid. 
EXAMPLE 17 
A solid antistatic agent was formed by admixing 25 grams of the 
polypropylene identified in Example 1 with 75 grams of 
N,N-bis-(2-hydroxyethyl) decylamine. 
The mixture was heated with high speed stirring. The resin formed clumps at 
160.degree. C.; at 165.degree. C., a resin mass was formed and, at 
240.degree. C., a viscous homogeneous phase formed and was poured onto a 
metal plate at room temperature. 
On cooling, the material was strong and dry. 
Each of the solid products made according to Examples 6 through 12 can be 
incorporated in polyethylene in an amount equivalent to 0.05% to 0.3% 
amine by weight, in polystyrene in an amount equivalent to 2 to 3% of 
amine by weight or in other olefinic polymers in effective amounts to 
impart good antistatic and slip characteristics to the blended polymer. 
The material is readily added to the olefinic polymer as, for example, in 
a mixture at a temperature above the softening point of the polymer, 
preferably above about 150.degree. C. by adding ground particles of the 
dry, solid antistatic agent to the molten olefinic polymer. 
Thus, as has been seen, the present invention provides an advantageous 
process for converting a normally liquid antistatic agent into a form 
capable of being handled as a solid. The resin carrier utilized to allow 
achievement of this objective need be present in only minor amounts. The 
resulting novel solid antistatic agent can then be incorporated in the 
virgin resin being treated in amounts far in excess of the level which can 
be achieved based on solubility characteristics of the liquid antistatic 
agent involved. Still further, in some situations, as can be seen from the 
subject examples, the solid antistatic agent appears to impart improved 
slip characteristics to the treated resin.