Note: Descriptions are shown in the official language in which they were submitted.
Technical Description of the Invention
The present invention relates to an internally
plasticized vinyl chloride copolymer which can be used in
those applications where externally plasticized vinyl chloride
is usedJe.g., as a vinyl film or sheeting material, in vinyl
wire and cable insulation, as vinyl flooring, and as bag
and tubing for blood transfusion equipment.
Externally plasticized vinyl chloride polymers
are well known. These products typically contain certain levels of
external plasticizer to give the polymers the required degree
of flexibility. The technique of external plasticization is
not, however, entirely satisfactory since the plasticizer tends
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C-4500
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1~99~49
to migrate to the surface of the finished product giving rise
to such problems as surface stickiness, gradual loss of plastici-
ty, and the danger of possible toxicological dangers to the
user from the plasticizer. Also,the aromatic plasticizers
used in such products give rise to copious smoke production when
burned and flex at rather high temperatures requiring a rather
high energy input during processing.
A number of ~rior art processes have been proposed
for formation of internally plasticized vinyl chloride copoly-
mers. The use of copolymers of a vinyl monomer and a poly-
merizable polyester, ~or example, an acrylate or a vinyl
e~ter of a polyester of an aliphatic hydroxycarboxylic acid,
was proposed in U.S. Patent No. 3,6~0,927 to C.S. Marvel et
al. An internally plasticized two-component vinyl chloride
~15 copolymer containing ~rom about 75% to about 95% vinyl chlor::de ~ -
and about 25% to about 5% of an ester of an unsaturated mono-
or polycarboxyllc acld, e g., a C~-Cl2 alkyl maleate, fumarate
or acrylate, was proposed in U.S. Patent No. 3,54~,661 to
A 0th et al. The present invention relates to a composltlon
contalnlng at least three baslc components. Finally, a four
component pol~ymer composition containing vinyl chloride, a
dialkyl maleate or fumarate, an alkyl ester o~ acrylic or
methacrylic acid and a monohydrogen, monoalkyl maleate or
fumarate was proposed in U.S. Patent No. 3,196,133 to R.A.
Piloni et al. ~or use as a solvent-based coating having both
good adhesiveness and flexibility. The Piloni et al. compo-
sltion utilizes a lower molecular weight Cl-Clo dialkyl
maleate or fumarate as one component whereas the present
invention contemplates UBe of the Cg-C22 dialkyl maleates
,, _ - - - . .
C-4500
1~9~49
and fumarates.
A plasticized polyvinyl chloride composition must
ha~e low temperature flexibility and physical toughness to
be commercially useful. The low temperature flexibility can
be measured by the well known Clash-Berg method with a value
o~ -25C. or lower being preferred, Physical toughness can
be deter~ined by measuring the tensile strength at break
with a value of about 1200 psi or higher being desired.
Standard ASTM test6 exist for both of the above determinations,
lo for example, ASTM D1043 and ASTM D638-72, respectively.
It is theorized that conventional external plast-
icization partially reduceSthe crystallinity of the vinyl
chloride polymer the~y achieving better low temperature
flexibility but leaving enough crystallinity so as not to
reduce the physical toughness of the polymer. Internally
plastici~ed vinyl chloride copolymers, on the other hand, fre-
quently reduce the crystallinity of the polymer to substantial-
ly zero if a high enough amount of plasticizing comonomers are
used. It was ~uggested by R. Liepins in "Polymer Engineering
and Science,"Vol. 9, No. 2 (March 1969), pp. 86-89 ~hat a
possible solution to this problem is the use of high molecular
weight plasticizing comonomers so that the mole fraction of
such comonomers is low whereas their weight percentage is high.
Although such comonomers as the Cg-C22 dialkyl fumarates and
maleates meet this description, their use with vinyl chloride
monomer does not give a vinyl chloride copolymer having the
desired low temperature flexibility and adequate physical prop-
erties,e.g., good tensile strength. As will be shown in Ex-
amples which follow, use of such comonomers as the high molecular
, . , . , . , .. . ; ,
C-4500
1~39~9~4~
weight dialkyl fumarates and maleates, or for that matter,
the high molecular weight alkyl acrylates, will produce a
product having the desired low temperature flexibility but
having other physical properties not suitable for the inten-
ded product, e.g., unacceptably low tensile strength.
It has been unexpectedly found that an internally
plasticized vinyl chloride polymer having a Clash-Berg value
of about -20C. or below, preferably -25C. or below, and a
tensile strength at break of at least 85c psi or higher,
preferably 1200 psi or greater, can be formed with convention-
al emulsion, suspension, bulk and solution polymerization
procedures by using a basic three component monomer charge
which contains certain amounts of vinyl chloride, a C2-ClO
alkyl acrylate and a C8-C22, preferably a Cll-C22, dialkyl
maleate or fumarate. The invention is an internally plasti-
cized copolymer which consists essentially of from about 45
to about 80~, by weight, of vinyl chloride, from about 15~
to about 54~, by weight, of a C2-Clo alkyl acrylate and from
about 1~ to about 15~, by weight, of a Cg-C22 dialkyl maleate
or fumarate copolymerized therein.` Mixtures of the respective
alkyl acrylates and of the dialkyl maleates of fumarates can
be used, if desired. A preferred copolymer is a terpolymer
containing from about60~to about 75~, by weight vinyl chloride,
from about 20~ to about 35~, by weight of the C2-ClO alkyl
acrylate, and from about 4~ to about 15~ of the Cg-C~2 dialkyl
maleate or fumarate copolymerized therein.
.
~9~9 C-4500
Representative C2-C10 alkyl acrylates which can
be used in the practice of the present invention include
ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-
butyl acrylate, sec-butyl acrylate, t-butyl acrylate, n-
and other isomeric pentyl acrylates, n-hexyl acrylate,
cyclohexyl acrylate, n-octyl acrylate, 2-ethyl hexyl acrylate,
and mixtures of the forego~ng acrylates.
The Cg-C22 dialkyl maleates and fumarates suitable
for use in the present invention can be formed, if desired,
0 by reacting a mixture of Cg-C22 aliphatic alcohols, e,g.,
a mixture of Cl2-C22 alcohol~, which are available co~mercial-
1~ as Conoco LTD alcohol from Continental Oil Co., with either
maleic anhydride or fumaric acid, as, for example, set forth
in Example 1 given below. Alternatively,individual C8-C22
dialkyl maleates or fumarates can be utilized. Representative
maleates and fumarates which can be used include di-2-ethyl-
hexyl maleate and fumarate,diundecyl maleate and fumarate,
didodecyl maleate and fumarate, ditridecyl maleate and
fumarate, dioctadecyl maleate and fumarate, and didocosa
'O maleate and fumarate and mixtures thereof. The mixed maleates
or fumarates can be made by mixing the separately prepared
dialkyl esters or by mixing the alcohols together and then
running the esterification reaction.
The copolymer of the present invention can be
'5 formed using conventional bulk, emulsion, suspension and solution
polymerization procedures. Suspension polymerization is
preferred since it avoids the problems of isolation of the
product from a latex that can be encountered using emulsion
polymerization techniques, the heat of reaction is more
so readily removed as compared to bulk polymerization procedures,
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1~99~49 C-4500
and no solvent recovery is needed as in solution polymerization.
suSPenSiOn polymerizatlon reaction mixtures comprise
from about 20% to about 45%, by weight, based on the amount
of water, o~ the above enumerated monomers in an aqueous
reaction medium. Also included will be from about 0.05% to
about 5%, by weight based on the weight of monomers, of a
suspending agent, such as methyl cellulose, hydroxyethyl
cellulose, hydroxypropyl methyl cellulose, gelatine, and the
like; from abo~ ~,005~ to about l~,by weight, based on the
Lo amount of m~nomer, of at least one monomer-soluble initiator,
such a~ azobisiso~tyr~nitrile, lauroyl peroxide, benzoyl
peroxide or isopropylperoxy dicarbonate, Polymerization is
conducted by heatlng the suspension containing the above
components to a temperature of from about ~5C. to about
75C. for about 2 to 12 hours with agitation ~eing ap~lied
throughout the course of the reaction. As is well known in
the art, the use of the more active of the above ~entioned
initiators will require use of either a lower temperature or
;~ shorter reaction time, or both, whereas use of the less active
initiators will require more severe conditions.
If emulsion polymerization is to be employed,
the above described suspending agent is replaced with from
about 0.2~ to about 2%, by weight, of an emulsifying agent,
such as sodium lauryl sulfate, potassium stearate, an alkyl
benzene sulfonate, an ammonium dialkyl sulfosuccinate, and
the like, and the monomer soluble initiator is replaced by
from about 0.1% to about 1% of a water-soluble initiator,
such as an alkali metal persulfate, perborate or peracetate,
ammonium persulfate, perborate or peracetate, the urea per- -
oxides, hydrogen peroxide, tertiary butyl hydroperoxide and
1~9~49 c-l~ 5 oo
the like. If desired, a redox initiator system such as
ammonium persulfate and sodium bisulfite or hydrogen per-
oxide and ascorbic acid can also be used as the initiator.
Polymerizatlon is carried out at similar temperatures and
over similar times as those used in suspension polymeriza-
tion.
If bulk polymerization is employed, the monomers
are polymerized in the presence of the above-described
amounts of the monomer-soluble catalysts alone under the
lo same temperature and time conditions described above in
connection wlth suspension and emulsion polymerization.
If solution polymerization is employed, the
monomers are polymerized in the presence of at least one
inert organic solvent, such as butane, pentane, octane,
benzene, toluene, cyclohexane, cyclohexanone, acetone,
isopropanol, tetrahydrofuran or the like. The selected
initiator should be soluble in the reaction medium. The
copolymer can either remain dissolved in the solvent at
the end of the polymerization or can precipitate from the
liquid phase during the polymerization In the former case,
the product can be recovered by e-~aporation of the solvent
or by precipitation of the polymer solution by combining
it with a non-solvent for the product. The same reaction
condition~ used in suspension and emulsion polymerization
can be used.
The final product of the present invention oan contain,
if desired, ~arious optional additives which are compatible
with the copolymer product and which do not adversely affect
the properties of said product. Included within this class
C-4500
1~9~3449
of additives are those he~t and light stabilizers, ultraviolet
stabilizers, pigments, fillers, dyes, and other additives
known to persons of ordinary skill in the art. A suitable -
listing of possible additives which a person of ordinary
skill in the art may use to select appropriate additives,
if desired, is given in Modern Plastics Encyclopedia, Vol.
51, No. loA, e.g., at pp. 735-754.
The following Examples illustrate certain preferred
embodiments of the present invention:
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11~9944~
C-4500
EXAMPLE 1
This example illustrates a procedure for preparing an alkyl
ester of fumaric acid which is suitable for use in preparing the
copolymer composition of this invention.
The reactants listed below were placed in a three liter
round bottomed flask equipped with a Dean & Stark trap, conden-
ser, stirrer, thermometer and nitrogen inlet:
Reagent Amount
Mixture of alcohols* 744 g.
Fumaric acid 174 g.
p-toluene sulfonic acid** 2 g.
Butylated hydroxytoluene** 0.02 g.
Varnish and Paint Makers Naphtha** 300 ml.
*available commercially as Conoco LTD alcohol from Continental
Oil Co. It comprises a mixture of Cl2-C22 branched chain alco-
hols having an average molecular weight of 248.
**the sulfonic acid is used as an esterification catalyst; the
toluene reagent, as a polymerization inhibitor; and the naphtha
as an azeotroping agent.
The reactants were heated and stirred at a temperature of
110-160C. for about 3~ hours, and 50 ml. of water was removed as
an azeotrope. The reactants were then heated with a nitrogen
purge at a temperature of from 180C. to 220~C to remove the
naphtha. The oily product which was obtained was washed with a
5~,by weight, solution of sodium hydroxide followed by water wash-
ings until the water was neutral by litmus paper testing. The
yield was 8~6 g. or 96~ of theory,and the product had a molecular
weight of 570. This product was designa~ed " Product A."
1~95~q~49 c-4500
EXAMPLE ?
This example illustrates a procedure for preparing
a vinyl chloride/fumarate ester/acrylate terpolymer composition
in accordance with the present invention. The fumarate ester
was prepared by the procedure set forth ln Example 1.
The reactants listed below were placed in a one-
quart soda bottle which was then frozen at -15 c . for two hours:
Reagent Amount
Water 300 g.
Hydroxypropylmethyl cellul~se (1~ soln.)* 35 g.
L0 2-ethylhexyl acrylate 30 g.
"A" from Example 1 5 g.
~)
* a~ suspending agent from Dow; Methocel K-~5.
To this chilled bottle W~9 then added 2.5 ml. of a 10%, by
weight, solution of isopropylperoxydicarbonate initiator in
.5 heptane and 65 g. of vinyl chloride monomer. The bottle was
capped and was clamped in a bottle polymerization apparatus
whlch was then rotated at 35 rpm with heating at ~5C. for 12
hours. After coollng to room temperature the bottle was vented
and no unreacted vinyl chlorlne monomer was detected. The
o product, a white suspension slurry, was filtered through a
Buchner funnel and was dried.
Using a simiIar,procedure a number of other samples
were also made along with other copolymer compo~itions for
comparlson. Table 1 sets forth the results:
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-11-
00~
1~9~449 C-4500
EXAMPLE 3
One hundred grams of each of the samples listed in Table
1 in Example 2 were mixed with the following ingredients:
Ingredient Amount (g,)
Epoxy stabilizer (G-62, a soybean oil
epoxide, sold by Rohn and Haas) 5
~ .
Barium-Cadmium Stabilizer (Nuostabe
V-1541, sold by Tenneco Chemicals, Inc.` 1.5
~ .
Phosphite stabilizer (Nuostabe V-1542,
sold by Tenneco Chemicals, Inc.) 1.5
Calcium stearate lubricant 0.5
Stearic acid lubricant 0.5
The samples wereeach processed on a 2 roll mill at 270F.-300F.
for 7-10 minutes and were compression molded and die cut. Each
was then tested by a variety of ASTM methods. The results are
shown in Table 2:
-12-
39~449
*
0~ ~D O u~
J O~ O 1~ IS~ O
0 1 C~J ~ U~ ~ ~ C~l
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o
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1~\ N C`J ~q
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C --I ~ C
:r: o ~ v ~ ~ o ~ ,~
O ri V ~ rl ~ ~
¢ rl V. ~ g N
- ~ = V V ~ I ca ~1
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u~ l V t~
O C ~ ~ ~ t) O ~
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u~ c~ cn *
oo5t~
i~99~5~ -
C-4500
.
The externally plasticized PVC (Sample 9) showed good
low temperature flexibility, as measured by its Clash-Berg read-
ing, and good tensile properties. The vinyl chloride/Cg fumarate
copolymer (Sample 3) was lacking in both low temperature flexi-
bility and elasticity, the vinyl chloride/Cl2-C22 fumarate
copolymer (Sample 4) had excellent low temperature flexibility
but was very poor in tensile strength, and the vinyl chloride/
acrylate copolymer (Sample 2) was somewhat deficient in low
temperature flexibility and ~ elongation at break. Sample 5
which contains 10~ or more of a fumarate ester is excellent in
low temperature flexibility if a reduction of the tensile strength
at break to about 850 to 900 psi can be tolerated. Samples 1,
6 and 8, which are the preferred compositions of this invention
had a Clash-Berg value of -24F. or lower, a tensile strength
~15 at break of 1200 psi or higher, and a ~ elongation at break
of at least 230~ or higher. Commercially useful, flexible
vinyl products can be made using these resin compositions
which contain no migratory plasticizers. These products will
avoid the aforementioned problems normally associated with
2~ plasticizer migration from externally plasticized PVC films.
The product of the present invention is, therefore,
an internally plasticized composition which does not possess
the surface stickiness, gradual loss of plasticity, danger
of possible toxicological dangers to the user from the plasti-
cizer, and copious smoke production when burned that are
characteristics of certain externally plasticized products
known to the prior art. In addition, the product of the
present invention flexes at a lower temperature than conven-
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1~9~4~ C-4500
tional externally plasticized products thereby requiring a
lower energy input for such fabrication techniques as milling
and the like.
The foregoing illustrates certain preferred embodi-
ments of the claimed invention. The scope of protection which
is sought is set forth in the claims which follow.
