ANTISTATIC VINYLIDENE CHLORIDE COATING COMPOSITION, AND FILM COATED THEREWITH

SUBSTANCE DE REVETEMENT ANTISTATIQUE A BASE DE CHLORURE DE VINYLIDENE ET PELLICULE AINSI COUVERTE

English Abstract

Abstract
A vinylidene chloride copolymer coating composi-
tion containing small amounts of a polybasic acid of
phosphorus, such as orthophosphoric acid, or sulfuric
acid, in combination with a mono- or diglyceride. Organic
polymeric films, such as polyester and regenerated cellu-
lose films, coated therewith exhibit excellent antistatic
properties. Such coated films can be run on various types
of machinery without problems due to static build-up.

Claims

CLAIMS
1. A coating composition comprising
(a) a copolymer of vinylidene chloride and
at least one other ethylenically
unsaturated monomer copolymerizable
therewith, said copolymer containing
at least 80% by weight of vinylidene
chloride,
(b) about 0.5 to 5% by weight, based on
said vinylidene chloride copolymer, of
a mono- or diglyceride,
(c) about 0.5 to 5% by weight, based on
said vinylidene choloride copolymer, of
sulfuric acid or a polybasic acid of
phosphorus, or mixtures thereof, and
(d) an antisticking agent.
2. The composition of claim 1, further
comprising
(e) about 0.1 to 6% by weight, based on
said vinylidene chloride copolymer, of
a linear film-forming polyester resin
having a molecular weight of at least
500 prepared by condensing a glycol and
a polyfunctional acid, at least 70% by
weight of said polyfunctional acid be-
ing an aromatic polyfunctional acid.
3. The composition of claim 2, wherein compo-
nent (c) is a polybasic acid of phosphorus.
4. The composition of claim 2, wherein compo-
nent (c) is orthophosphoric acid, pyrophosphoric acid, or
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phosphorous acid.
5. The composition of claim 2, wherein compo-
nent (c) is orthophosphoric acid.
6. The composition of claim 2, wherein compo-
nent (c) is sulfuric acid.
7. The composition of claim 5, wherein compo-
nent (d) comprises wax and particulate.
8. The composition of claim 5, wherein compo-
nent (d) consists of 2.7 to 3.3% by weight of behenic
acid, 0.4 to 0.6% by weight of carnauba wax, 1.2 to 1.8%
by weight of candelilla wax, and 0.5 to 1.0% by weight of
stearamide, all based on said vinylidene chloride copoly-
mer.
9. The composition of claim 8, wherein compo-
nent (c) is orthophosphoric acid in an amount of about 1
to 3% by weight, based on said vinylidene chloride copoly-
mer.
10. The composition of claim 9, wherein compo-
nent (b) is present in an amount of about 0.5 to 3% by
weight, based on said vinylidene chloride copolymer.
11. The composition of claim 10, wherein compo-
nent (a) is at least one copolymer of vinylidene chloride,
each copolymer being a copolymer of vinylidene chloride
and at least one monomer of the formula
<IMG>
where R is hydrogen, halogen, or a saturated aliphatic
radical, and X is chlorine, bromine, fluorine, - CN,
- C6H5, - COOH, - HC=O, - OC6H5, - CONH2, - CONHR',
- CONR'2,
-28-

<IMG> , or <IMG>
where R' is alkyl,
said copolymer containing about 88 to 94% by weight of
vinylidene chloride.
12. The composition of claim 11, wherein com-
ponent (e) is the condensation product of
(i) at least one diol of the formula
HOCH2?CH2?xCH2OH
where x is 0 to 10, and
(ii) at least one diacid, wherein at
least 70% by weight of said diacid
is an aromatic diacid and up to 30%
by weight of said diacid is an
acyclic dicarboxylic acid of the
formula HOOC-CH2-X-CH2-COOH
where X is a chain of 2 to 8
carbon atoms.
13. The composition of claim 12, wherein the
diol is ethylene glycol, the aromatic diacid is at least
one of isophthalic acid and terephthalic acid, and the
acyclic dicarboxylic acid, if present, is at least one of
adipic acid, sebacic acid, succinic acid, or azelaic acid.
14. The composition of claim 13, wherein compo-
nent (e) is present in an amount of about 0.2 to 1% by
weight, based on said vinylidene chloride copolymer.
15. The composition of claim 14, wherein compo-
nent (b) is glyceryl monostearate, glyceryl monopolmitate,
glyceryl monolaurate, or mixtures thereof.
16. The composition of claim 2, wherein compo-
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nent (d) is a particulate, and further comprising
(f) at least one resinlike component
capable of crosslinking.
17. The composition of claim 5, wherein compo-
nent (d) is a particulate, and further comprising
(f) an amino resin in an amount of 0.1
to 20% by weight, based on said
vinylidene chloride copolymer.
18. The composition of claim 6, wherein
component (d) is a particulate, and further comprising
(f) an amino resin in an amount of 0.1
to 20% by weight, based on said
vinylidene chloride copolymer.
19. The composition of claim 17, wherein the
amino resin is a melamine-formaldehyde resin.
20. The composition of claim 19, wherein compo-
nent (c) is orthophosphoric acid in an amount of about 1
to 3% by weight, and component (b) is present in an amount
of about 0.5 to 3% by weight, both based on said vinyli-
dene chloride copolymer.
21. The composition of claim 20, wherein compo-
nent (a) comprises a copolymer of vinylidene chloride and
at least one monomer of the formula
<IMG>
where R is hydrogen, halogen, or a saturated aliphatic
radical, and X is chlorine, bromine, fluorine, - CN,
C6H5, - COOH, - HC = O, - OC6H5, - CONH2, - CONHR',
CONR'2,
-30-

<IMG> , or <IMG>
where R' is alkyl,
said copolymer containing about 88 to 94% by weight of
vinylidene chloride, and component (e) is the condensation
product of
(i) at least one diol of the formula
HOCH2?CH2?xCH2OH
where x is 0 to 10, and
(ii) at least one diacid, wherein at
least 70% by weight of said diacid
is an aromatic diacid and up to 30%
by weight of said diacid is an acyclic
dicarboxylic acid of the formula
HOOC-CH2-X-CH2-COOH
where X is a chain of 2 to 8 carbon
atoms.
22. An organic polymeric base film coated on at
least one side thereof with a continuous, adherent coat-
ing composition of claim 1.
23. The film of claim 22, wherein the base film
is a polyester film.
24. The film of claim 23, wherein the polyester
is a polyethylene phthalate.
25. The film of claim 24, wherein the polyester
is polyethylene terephthalate.
26. The film of claim 22, wherein the base
film is a regenerated cellulose film.
27. An organic polymeric base film coated on at
least one side thereof with a continuous, adherent coating
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composition of claim 5,
28. The film of claim 27, wherein the base
film is a polyester film.
29. The film of claim 28, wherein the polyester
is a polyethylene phthalate.
30. The film of claim 29, wherein the polyester
is polyethylene terephthalate.
31. The film of claim 27, wherein the base
film is a regenerated cellulose film.
32. An organic polymeric base film coated on
at least one side thereof with a continuous, adherent
coating composition of claim 15.
33. The film of claim 32, wherein the base
film is a polyester film.
34. The film of claim 33, wherein the polyester
is a polyethylene phthalate.
35. The film of claim 34, wherein the polyester
is polyethylene terephthalate.
36. The film of claim 32, wherein the base
film is a regenerated cellulose film.
37. An organic polymeric base film coated on
at least one side thereof with a continuous, adherent
coating composition of claim 16.
38. The film of claim 37, wherein the base
film is a polyester film.
39. The film of claim 38, wherein the polyester
is a polyethylene phthalate.
40. The film of claim 39, wherein the polyester
is polyethylene terephthalate.
41. The film of claim 37, wherein the base
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film is a regenerated cellulose film.
42. An organic polymeric base film coated on
at least one side thereof with a continuous, adherent
coating composition of claim 21.
43. The film of claim 42, wherein the base
film is a polyester film.
44. The film of claim 43, wherein the polyester
is a polyethylene phthalate.
45. The film of claim 44, wherein the polyester
is polyethylene terephthalate.
46. The film of claim 42, wherein the base
film is a regenerated cellulose film.
47. A subcoated organic polymeric base film
coated on at least one side thereof with a continuous,
adherent coating composition of claim 1.
48. The film of claim 47, wherein the base
film is subcoated with an acrylic polymer.
49. The film of claim 48, wherein the acrylic
polymer is crosslinked.
50. The film of claim 22, wherein the base
film is a coextruded polyester film.
51. The composition of claim 1, further
comprising
(e) about 0.1 to 5% by weight, based on said
vinylidene chloride copolymer of a partial organic ester
of phosphoric acid.
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-33-

52. The composition of claim 2, further
comprising
(f) about 0.1 to 5% by weight, based on said
vinylidene chloride copolymer of a partial organic ester
of phosphoric acid.
53. The composition of claim 52 wherein the
partial organic ester of phosphoric acid is lauryl
hydroxypoly(oxyethylene) hydrogen phosphate.
54. An organic polymeric base film coated
on at least one side thereof with a continuous, adherent
coating composition of claim 51.
55. An organic polymeric base film coated on
at least one side thereof with a continuous, adherent
coating composition of claim 52.
56. An organic polymeric base film coated on
at least one side thereof, with a continuous, adherent
coating composition of claim 53.
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Description

1~4~'~3
B~ClCGROUl~l) OF THE IN~ENTION
The invention~concerns improvements in and re-
lating to the antistatic propcrties of coating composi-
tions of vinylidene chloride copolymers used as coatings
on organic polymeric films.
It is well known in the art to apply coating
compositions of the above-specified type to various base
films so as to achieve combinations of properties not
possessed by either the base film or coating alone. Thin
films, however, are prone to develop static charges which
cause the films to stick and ~am in machinery used for
packaging and laminating operations. In order to meet
such problems, it is known to add to coating compositions
small amounts of substances which confer antistatic
properties, or to aftersize coated films with similar
materials.
For example, U. S. 3,677,811 discloses the
incorporation of an antistatic composition comprising a
mixture of a compound such as bis(2-hydroxyethyl) myristyl
amine or bis~2-hydroxyethyl) tallow amine and one or
:
more glycerides into a coating of a heat sealable polymer
that is applied to a base film.
~- ` Nevertheless, static problems remain in many
:~ instances. To cite but a single example, solvent coating
;~ of polyester films with vinylidene chloride copolymer --
. -, -:
sometimes referred to as saran) coating compositions
results in films having a very high static propensity.
- Although antistats have been added to the coating
; composition, they are either not sufficiently effective
to eliminate static build-up, or they adversely effect
:
-2-
,,

; 3
other properties such as the hcat seal strength, especially
at high humidities. Saran-coated film can be aftersi~ed
to lower the static propensity, but this has the disad-
vantages that the expense of an extra coating operation
is required, and if too much aftersize is used, the heat
seal strength is lowered to an unacceptable level. Also,
in the case of aftersizing a coated polyester film, the
film tensions required in tne drying section of the coater
result in increased film shrinkage upon subsequent reheating.
SU~IMARY OF THE INVENTIO~
It has now been found that when a polybasic
acid of phosphorus, or sulfuric acid, is used in combina-
tion with one or more mono- or diglycerides in a saran
coating composition, a film having excellent antistatic
properties is obtained. More specifically, according to
; the present invention, there is provided a coating compo-
sition comprising
(a) a copolymer of vinylidene chloride and at least one
other ethylenically unsaturated monomer copolymer-
izable therewith, said copolymer containing at
least 80% by weignt of vinylidene chloride,
(b) about 0.5 to 5% by weight, based on said vinylidene
chloride copolymer, of a mono- or diglyceride,
(c) about 0.5 to 5% by weight, based on said vinylidene
- chloride copolymer, of sulfuric acid or a polybasic
acid of phosphorus, or mixtures thereof, and
(d) an antisticking agent.
Additionally, it has been found that about
0.1 to 5% by weight based on said vinylidene chloride
copolymer, of a partial organic ester of phosphoric acid

can be ad~ed to the coating composition to cxtcnd the
existence of the excellent antistatic properties realized
by use of the com~osition.
According to other aspects of the invention,
there are also provided films having a coating of the
above composition on at least one side thereof, and coat-
ing baths of the coating composition in a volatile
organic solvent.
The improved coating composition of the inven-
tion provides coated films which have a very low staticpropensity. The need to aftersize the coated film is
eliminated, and the coated films have good dimensional
stability.
Surprisingly, when orthophosphoric acid is
~; used in the coating composition, improved heat-sealing
performance is also observed. This improvement is man-
ifest in both extending the attainment of good heat-
seals to lower sealing temperatures, and improving the
heat seal strength at the ordinary sealing temperatures.
Improved release from crimped sealing jaws is also observed.
Accvrdingly, use of a polybasic acid of phos-
phorus is preferred, and orthophosphoric acid is highly
~- preferred. To meet a desire or requirement for the
presence of antistatic properties over a period of more
than six months, the combined use of phosphoric acid
and partial organic esters of phosphoric acid is pre-
- ferred.
In the case of sulfuric acid, in some instances
the antistatic properties have been observed to develop
3Q more quickly than in the case of orthophosphoric acid.
..:

;3`73
Also, improved hcat seal valucs at low sealing tempera-
tures have been observed in some cases but not in others,
while some sacrifice in heat seal values at ordinary
sealing temperature is seen.
DESCRIP~'ION OF THE PREFE~RED EMBODIMENTS
Copolymers of vinylidene chloride and at least
one other ethylenically unsaturated monomer are well
known in the art for use in saran coating compositions.
Representative monomers useful in preparing these vinyl-
idene chloride copolymers include: acrylic acid; acryl-
ates such as methyl, ethyl, isobutyl, butyl, and 2-ethyl
hexyl acrylates; methacrylates such as methyl, phenyl,
cyclohexyl, methoxyethyl and chloroethyl methacrylate;
methyl alpha-chloroacrylate; methyl isopropenyl kçtone;
acrylonitrile methacrylonitrile methyl vinyl ketone;
vinyl chloride; vinyl acetate; vinyl propionate; vinyl
chloroacetate; vinyl bromide; styrene; vinyl naphthalene;
ethyl vinyl ether; N-vinyl phthalimide; N-vinyl succin-
imide; N-vinyl carbazole; acrylamide; methacrylamide;
phenyl vinyl ketone; diethyl fumarate; methacrylic acid;
itaconic acid; dimethyl itaconate; and the like. The
~- most useful monomers fall within the general formula
R
CH2 C ~
:' X
wnere R is hydrogen, halogen, or a saturated aliphatic
radical, and X is one of -Cl, -Br, -F, -CN, -C6H5, -COOH,
-C~ , -C~
~ 30 OR' R'

-Cl~~O, -OC6l~5, -CONl~2, -CONII-R' and -CONI~'2 where R'
is alkyl.
Copolymers of vinylidene chloride with an
ethylenically unsaturated monomer are generally described
in terms of the weight ratio of the monomer units in the
copolylner. For purposes of this invention, the vinylidene
chloride content should be at least 80% to obtain a tack-
free coating, and preferably at least 88% for optimum
barrier properties. By "barrier properties" is meant
that the copolymer is relatively impermeable to water
vapor. In general, the vinylidene chloride content should
not exceed about 94~ as copolymers of higher vinylidene
chloride content have poorer heat sealability, although
~; they have excellent barrier and tack-free properties.
Useful copolymers generally have an intrinsic viscosity --
of at least 1.3 as measured on a 1% concentration of
copolymer in tetrahydrofuran at 25C.
Although a single vinylidene chloride copolymer
~ is generally used, in some cases it is advantageous to
`~ 20 use a mixture of two or more such copolymers.
The coating composition contains one or more
mono- and diglycerides. Such compounds are mono- and
diesters of glycerine with fatty acids. The longer
chain acids having up to 22 carbons or more are most
useful. Especially preferred are glyceryl monostearate,
glyceryl monopalmitate and glyceryl monolaurate. Mix-
tures of them can be used. The glyceride is used in an
amount of about 0.5 to 5% by~eight, preferably 0.5 to 3
by weight, based on the vinylidene chloride copolymer.
While more than 5% could be use~, no advantage is seen in
this.

~i4'~ 3
Thc coating com~osition also contains a poly-
basic acid of phosphorus, or sulfuric acid. Examples
of polybasic acids of phosphorus include orthophosphoric
acid, pyrophosphoric acid, polyphosphoric acid, and
phosphorous acid. Orthophosphoric acid is most pre-
ferred. This constituent is used in an amount of about
0.5 to 5~ by weight, based on the amount of vinylidene
chloride copolymer. Preferably, the amount is 1 to 3
by weight. While more than 5% could be used, no ad-
vantage is seen in this. Mixtures of the acids can also
be used.
The coating composition can contain one or
more partial organic esters of phosphoric acid. The
partial organic esters of phosphoric acid useful herein
can be structurally represented by the formula
[R - (CHR'-CHR" ~)n]x ~ P(O)-(OH)y
wherein R is the residue of an alkylated phenol having
, .
1 to 36 carbon atoms in the alkyl group or an alkyl
hydroxy having 6 to 27 carbon atoms in the alkyl group;
R' and R" are H or methyl; n is 1 to 150; x is 1 to 2;
- - y is 1 to 2; and x ~ y is 3. Such compounds can be
- generally characterized as phosphate esters of nonionic
surfactants. Examples of such esters having an alkyl
hydroxy residue include: lauryl hydroxypoly(oxyethylene)
~ dihydrogen phosphate, lauryl hydroxypoly(oxyethylene)
-~ monohydrogen phosphate, and mixtures thereof; and the
corresponding hexy~ stearyl, docosyl, heptacosyl, and
-~ the like, phosphates. ~bove-mentioned lauryl esters are
- preferred such that, in the formula, R is 12 carbon
atoms, R' and R" are hydrogen, n is 4 to 4.5, x is
. ~ ,
--7--

'7~
either 1 or 2, and y is, respectively, either 2 or 1.
A mixture of the lauryl esters is usually used. E~amples
of such esters having an alkylated phenol residue include
nonylphenylpoly(oxyethylene)di- and monohydrogen phos-
phate and corresponding cresyl, docosyl, dioctadecyl,
and the like, phosphates. The ester is used in an
amount of about 0.1 to 5% by weight, preferably 0.3 to
2~ by weight, based on the vinylidene chloride copolymer.
While more than 5% could be used, no advantage is seen
in this.
In making up the coating baths for applying
the coating compositions, when orthophosphoric acid is
used, the commercially available concentrated, or 86~,
acid has been used. In the case of sulfuric acid, con-
centrated, or 98~, acid has been used. Although the
` acid component has been added as the final ingredient
- in preparing the coating bath, no reason is seen why
it could not be added before addition of other components.
While the use of mono- and diglycerides in
-; 20 coating compositions to achieve antistatic properties
is known, the present invention provides substantial
improvement in antistatic properties over that provided
by the glycerides. The combination of the glyceride and
; acid is more effective than the use of either constituent
alone. When glyceryl monolaurate is used, less ortho-
phosphoric acid is required to achieve the same general
level of antistatic properties than when glyceryl
monostearate is used.
Also, the use of above~describcd partial
organic esters of phosphoric acid is known to achieve
--8--

'f3
antistatic properties. Those antistatic properties
are short-lived, however, when compared with the
duration of antistatic properties achieved by the
combination of the partial organic esters of phos-
phoric acid as one component and the mixture of
phosphoric or sulfuric acid and glycerides as
another component. The duration of antistatic
properties exhibited by the combination of com-
ponents- is greater than the duration of such
properties exhibited by either component taken
alone.
The composition also contains an anti-
sticking agent. By this term is meant those
materials well known in the art which provide
antiblocking characteristics and improved surface
properties with respect to release from crimped
and smooth sealing jaws and other hot surfaces.
These include a wide variety of synthetic and
natural waxes, both paraffin and ester types,
behenic acid, stearamide, etc., and particulates,
such as talc, clays, alumino silicates, silica,
insoluble polymers, and the like. Ordinarily these
are all used in small amounts, although in some
kinds of film the total of them can be as much
as 10% by weight, based on the vinylidene chloride
copolymer. A combination of 2.7 to 3.3% by weight
behenic acid, 0.4 to 0.6~ by weight carnauba wax,
1.2 to 1.8% by weight candelilla wax, and 0.5 to
1.0% by weight of stearamide has been found to
be especially good.
.- .~ _ _
:~i

4~'73
In order to achieve good adhesive bonding
between the coating composition and the base film,
especially when the latter is a polyester film, it
is preferred to include in the coating composition
about 0.1 to 6%, and preferably 0.2 to 2~, by weight,
based on the vinylidene chloride copolymer, of a linear
polyester resin prepared by condensing a glycol and a
polyfunctional acid, at least 70~ by weight of said
polyfunctional acid being an aromatic polyfunctional
acid. The improved adhesive bonding is achieved without
unduly affecting recognized properties of the vinylidene
chloride coating such as low water vapor permea~ility
and good heat sealability.
Linear polyester resins, which can contain up
to 30% by weight of an aliphatic polyfunctional acid,
are well known in the art and are generally prepared
by condensing the selected acid(s) with a diol of the
formula
HocH2tcH2txcH2OH
where x is 0 tc 10. Particularly useful diols include
ethylene glycol and propane-1,3-diol.
Generally both the aromatic acid and aliphatic
acid, if present, will be diacids to produce a linear
polyester. Thus, the aromatic acid is generally at least
one of naphthalene dicarboxylic acid, isophthalic acid,
or terephthalic acid. The aliphatic diacid, if present,
is generally an acyclic dicarboxylic acid of the formula
HOOC-CH2-X-CH2-COOH
where X is a chain of 2 to 8 carbon atoms, such as
-10-

i~4~ 3
adipic acid, sebacic acid, succinic acid, or azelaic
acid.
Useful linear polyester resins are capable of
forming films and thus have a molecular weight greater
than about 500. The molecular weight must be low enough,
however, that the polyester resin is soluble in the solvent
medium selected for the coating composition. Polyester
resins within this molecular weight range have no
plasticizing effect on the vinylidene chloride copolymer
as evidenced by similar heat seal temperature obtained
irrespective of the presence of the polyester.
Linear copolyesters disclosed in V. S. Patent
2,892,747 to John Dye have proven to be particularly
useful for this purpose. These copolyesters are ~
- trans-esterification products of the lower alkyl
esters of terephthalic acid, isophthalic acid, and at
least two acyclic dicarboxylic acids such as adipic acid,
azelaic acid, and sebacic acid. A commercially available
polyester which can be used is "Vitel"*PE 100 sold by
20 Goodyear Chemical Company.
For some purposes, coated films which are not
heat sealable or only poorly sealable are satisfactory,
and in some cases even desirable, as they have excellent
antiblocking properties. For example, films which will be-
come one component of a laminar structure (along with other
films such as coated heat sealable films, polyethylene,
- polypropylene, and the like, the laminate being made by
adhesive lamination, by extrusion coating, or by heat and
pressure lamination) need not be heat sealable, but they
30 nevertheless should have good antistatic properties to
* denotes trademark
.
' .

'73
avoid problems caused b~ static in the laminating
apparatus. Such coated films can be madc by adding to
the coating composition a component which degra~es or
destroys the heat sealing properties. Resinlike materials
capable of crosslinking are suitable for this purpose.
Crosslinkable components such as alkyd resins and/or amino
resins which are condensation proclucts of an amine, as
for example melamine, diazine, urea, cyclic ethylene
urea, cyclic propylene urea, thiourea, cyclic ethylene
thiourea, alkylmelamines, aryl melamines, benzoquanamines,
guanamines, alkyl guanamines, and aryl guanamines with
an aldehyde as for example formaldehyde, or al~oxylized
compounds such as hexamethyoxymelamine, are suitable.
The condensation product of melamine with formaldehyde is
especially useful. Such material can be used in an amount
of 0.1 tc 20~ by wei~ht, based on the vinylidene chloride
copolymer.
Coating baths of the above described coating
compositions are prepared by dissolving the vinylidene
chloride copolymer in a volatile organic solvent such as
tetrahydrofuran, toluene, methyl ethyl ketone, or mix-
tures thereof. Conveniently, the glyceride, linear
polyester, waxes, partial ester of phosphoric acid,
crosslinkable resin; etc., are added to the vinylidene
chloride bath, preferably after having been dissolved
in the same solvent as is present in the coating bath.
The inGrganic acid can be added at any time, but is
generally added after all the other components have
been dissolved or added. The coating composition is
- 30 applied to one or more surfaces of the selected
-: ,
-12-

9'~3
substrate using conventional appar~tus such as a gravure
roll or doctor roll, followed by drying to remove the
solvent.
The above described coating compositions can
be coated onto a variety of base films and surfaces,
in particular, films of organic polymers. Especially
useful are those where the base film surface is regen-
erated cellulose, polyester, polyamide, polyacrylates
and methacrylate, polyepoxide, polyvinyl chloride,
polyvinylidene chloride, polyacrylonitrile, and poly-
olefins such as polyethylene and polypropylene. The
; antistatic composition of this invention is useful and
~ effective when applied to any film or surface which
;~ exhibits static buildup in the absence of the
composition. Representative polyester substrates
include polycarbonates such as those prepared from
bisphenol A; and 2,6-naphthalate polyesters. Preferred
substrates include polyethylene phthalates, such as
polyalkylene terephthalate polyesters prepared by
reacting terephthalic acid (or a dialkyl ester thereof)
with glycols of the series HO~CH~tnOH where n is an
integer greater than 1 but not exceeding 10. Suitable
glycols include ethylene glycol, trimethylene glycol,
hexamethylene glycol and the like, Other functional
compounds which can be reacted with terephthalic acid
or with a dialkyl ester of terephthalic acid to pro-
duce linear polyester types, include p-xylene glycol,
hydroquinone, and cyclic glycols. Other polymers
-~ which can be used include polyalkylene terephthalate-
containing modifiers such as dibasic acids including
-13-

`3'~'3
among othcrs, isophthalic acid, sebacic acid, adipic
acid, sulfonated derivativos and the like. In a
preferred embodiment, the coating composition is
applied to a polyethyler.e terephthalate film which
has been oriented by stretching in both the machine
and transverse directions.
The base films may be primed or subcoated,
as is known in the art, with various materials sucn
as acrylics.- Crosslinked acrylics such as described
in German Offenlegungsschrift P 25 13 423, can also
be used as a subcoat. The base film may also be a
laminate or coextruded dual-layer polyester film.
The base film may range in thickness from
several mils to a small fraction of a mil. Most
often, the thickness will range from about 1 mil
to about half a mil.
The amount of coating applied will ord-
inarily be up to 5 g./m.2, and most often be in
the range of 2.5 to 3.5 g./m. , in which range
good barrier properties are attained. When barrier
properties are not required, adequate antistatic
properties can be attained at coating weights as
low as 0.1 g./m.2. Difficulty is encountered in
achieving uniformity of coating at coating weights
below 0.1 g./m.2.
The films of this invention possess
properties which make them admirably suited for
use as packaging materials for foods such as
fresh produce, meats, and baked goods, for
-14-

~149'73
household products such as sponges and the like, and
for industrial uses such as photographic microfilm
base and engineering reproduction materials.
In the examples that follow, film properties
are assessed by tests described in the following
paragraphs.
Water vapor transmission rate (~VTR) is
measured according to ASTM Method E-96, Procedure
E, and is expressed in grams of water transmitted
per 100 square inches per 24 hours.
Heat seal strength is measured as follows.
A piece of the coated film is folded in half, and
parallel strips one-inch wide are cut perpendicular
to the fold line. Each folded strip is sealed be-
tween sealing bars 3/4 inch wide, the top bar
being metal coated with polytetrafluoroethylene
and heated, the bottom bar being rubber and un-
heated, at a pressure of 5 psi and a dwell time
of 1/4 second. The temperature of the upper bar
is varied to test the seal strength at various
temperatures. The resulting strips ~usually four
samples for each film) are tested by oPeninq each
set at the free end, placing them in a Suter testing
machine, and pulling them apart. The highest force in
grams required to pull the strips apart is taken as a
measure of the heat seal bond strength. Heat seals can
be measured on the coated film as is, and/or after condi-
; tioning for 3 days at 35% or 81~ relative humidity (~), the
latter test being a more severe test of the quality of the
--15--

4~73
film coating.
Surface resistivity, which is a measure of anti-
static properties, is measured by ASTM method D-257-66.
Better antistatic properties correlate with lower surface
resistivity. Surface resistivity of 10l3 corresponds to
poor antistatic properties, while surface resistivities of
106 to 108 represent excellent antistatic properties.
EXAMPLES l-17
A coating bath of a saran copolymer (either saran
A, which is 91/4/5/0.3 parts by weight vinylidene chloride/
acrylonitrile/methyl methacrylate/itaconic acid, or saran B,
which is 90/7/3/0.3 parts by weight vinylidene chloride/
methacrylonitrile/methyl methacrylate/itaconic acid) was
prepared as follows.
Tetrahydrofuran (500 cc) was placed in a flask at
` 40C., and 1 gram of polyestex resin ("Vitel" PE 100~ was
placed in the flask and dissolved upon stirring for 30
minutes. Toluene ~333 cc) was added, followed by all of
the solids. In all of the examples and controls, the solids
include:
200 g. saran resin
2 g. talc
l g. carnauba wax
3 g. candelilla wax
1 g. stearamide ~"Armid"* 18
6 g. behenic acid ("Hystrene"* 7022~
An amount of a glyceryl monoester indicated in Table I was
also added with the other solids. An additional 240 cc of
tetrahydrofuran was added. The composition was stirred for
an hour and then 86~ orthophosphoric acid in an amount indi-
cated in Table I was added.
* denotes trade mark
-16-
.

i~L14~73
Tl1e coating bath was applied to both sides of
an 0.48 mil (12 microns1 oriented heat set polyethylene
terephthalatc film on an ll-inch (28 cm.) widc doctor
roll coater at a speed of 90 feet per minutc (27 m./min.)
and the solvent was removed in a towcr at l20UC.
The test results for the coated films are shown
in Table I. It can be seen that the films of the invention
exhibit significant improvement in heat seal strength, in
having consistently good heat seals at the lower sealing
temperature, and in lower surface resistivities.
-17-

~$149~73
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:

'73
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A coating composition~was prcpared by dissolving
1 gram of polyester ("Vitel" PE 100) in 100 ml. of
tetrahydrofuran. This was combined with a bat]l containing
273 ml. of toluene, 640 ml. of tetrahydrofuran and 200
grams of saran A. To this was added 60 ml. of toluene with
1 g. carnauba wax, 3 g. candelilla wax, 1 g. "Armid" 18,
6 g. glyceryl monostearate, 6 g. behenic acid and 2 g. talc.
Finally 3 g. of concentrated sulfuric acid was added.
The film was coated as described in Examples 1-
17. The coating weight was 3.3 g./m. . The surface
resistivity was 2.5 (6).
EXAMPLE 19
The coating formulation of Example 18 was
repeated with 1.5 g. of sulfuric acid. The surface
resistivity of coated film was 1.3 (8) and the WVTR 0.33.
EXP~lPLE 20
The formulation of Example 18 was repeated with
saran B and 3 g. sulfuric acid. The initial surface
resistivity was 1.3 (7). After 24 hours at 35% RH the
surface resistivity was 1.3 (9), and the ~VTR was 0.39.
EX~PLES 21-24
A comparison is shown between orthophosphoric
and sulfuric acid formulations applied to polyester film
in Table II. The coating compositions are otherwise
as given in Example 18, with the exception that the saran
is either A or B as identified in Table II. The heat
seal strength of the phosphoric acid formulations are
better than for sulfuric acid.
--19--
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973
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--20--

~14~'73
EX~ '5 25-~7
Additional coating haths and coatcd films were
prepared as in Examples 1-17, having the compositions
indicated in Table III. Heat seal and surface resistivity
data for the coated film is also ~iven in Table III.
-21-

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--22--

Comparison of ~xample 26 with Example 25 shows
that it is the glyceride and inorganic acid which are
responsible for the improv~d heat seals and low surface
resistivity. Comparison of Examples 26 and Control G sho~s
that the improved properties are not obtained with the
inorganic acid alone. Example 27 shows a highly satisfactory
- result of very low surface resistivity and good heat seals
when a mixture of sulfuric and orthophosphoric acids is
used.
EXAMPLE 28
Examples 20-24, above, indicate that the
surface resistivity of coated films tends to increase
with passage of time. The following example is provided
as a showing of the long-lived antistatic character of a
combination of partial organic esters of phosphoric acid
and a mixture of inorganic acid with glycerides.
Coating baths were prepared as described in
Examples 1-17 using saran B and 6 grams of glyceryl
monostearate. Orthophosphoric acid and a mixture of
lauryl hydroxypoly(oxyethylene)mono- and dihydrogen
phosphates were added in amounts indicated in Table IV
to yield five different coating compositions. The
lauryl phosphate ester, used in this example, can be
characterized as a mixture of alpha-dodecyl-omega-
hydroxypoly(oxyethylene)dihydrogen phosphate and mono-
hydrogen phosphate esters having an acid number of 103-
lll and produced by the esterification of the conden-
sation product of 1 mole of n-dodecyl alcohol with
4-4.5 moles of ethylene oxide.
-23-

i~l4~'~3
The coating compositions were applied to
0.4~ mil (12 micron) oriented heat set polyethylene
terephthalate film in the manner described above in
Examples 1-17. The test results for the coated films
are shown in Table IV. It can be seen that the film
bearing the combination of the phosphoric acid ester
as one component and phosphoric acid as another component
exhibit antistatic properties of longer duration than
films bearing either of those components taken above.
-24-

1~14~'73
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--25--
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~14~i`Y3
EXAMPLE 29
Samples of film prepared as in Example 8 were
tested on packaging machinery. In a test on a Campbell
Wrapper using a crimp jaw sealer the coated film had
excellent antistatic properties and better than those of a
coated film sold commercially for the same end uses, but
not containing the antistatic agents of the invention.
The seal strength was retained even after exposure for
3 days at 29~C. and 80% RH showing good high humidity
performance. Similar results were obtained on a Mira Pak
packaging machine.
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-26-