Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to emulsion copolymers
of vinyl halides, such as vinyl chloride, with ethylene or
monoethylenic ester which has been modified to introduce
improved thermosetting cure capacity. These emulsion copoly-
mers are known to be useful as binders for nonwoven fabrics,
as impregnants for woven fabrics, as a binder in printing
pastes, as laminating adhesives, as paints, and for other
similar purposes. These emulsion polymers are illustrated,
for example, by United States Patent 3,647,615 where N-
methylol acrylamide is used to modify vinyl chloride copoly-
mers in order to provide the desired curing characteristics.
This invention has,as its main objective, the achievement
of improved cure characteristics, which can be demonstrated
by the achievement of increased insolubilization after cure.
In connection with the thermosetting characteris-
tics which it is desired to achieve in accordance with the
invention, the increased insolubilization which is achieved
leads to many important benefits. With particular reference
to fabrics which have been treated with the emulsions of the
invention and then baked in order to cure the deposited copoly-
mer, wash resistance and crocking are improved when the emul-
sion is used as a binder in a printing paste, nonwoven web
integrity is improved when the emulsion is used as a binder
for a nonwoven web, durability to washing is improved when the
emulsion is used to modify the hand of a woven fabric, wash
and solvent resistance are improved when the emulsion is used
in a foam applied to a fabric to serve as a drapery backing,
and peel strength is improved when the emulsion is used for
laminating purpose. It is stressed that vinyl halides, such
as vinyl chloride and ethylene, polymerize poorly from the
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standpoint of achicving desircd hi~h molecular woight, makin~ the
i~roved distribut;on of cross-lin~ing obtained herein of especial
significance.
As will be appreciated, the invention, likc the prior art,
is concerned with aqueous emulsions in which the aqueous medium has
colloidally suspended there;n an emulsioll copolymer of vinyl halide,
which has becn modified to provide the propertics noted abovc.
Copolymers with ethylene arc ~articularly contcmplnted.
~ n accordance with the invention, an aqueous cmulsion com-
prising an aqueous medium having colloidally suspended therein an
emulsion copolymer of from 35% to 96.5% of vinyl chloride, from 3% to
60% of ethylene, and from 0.5 to 15% of monomers providing ther -
setting characteristics and comprising at least 0.5% of the N-methylol
functional addition product of formaldehyde with an allyl carbamate
having the formula
,Rl O / H
2 C CH2 o ~ R20 ~ H
in which Rl is hydrogen or methyl, R2 is an alkylidene group containing
from 2-4 carbon atoms, and n is an integer from 0-10, preferably from
0-2, and most preferably 0.
Yarious allyl carbamates are useful herein, especially allyl
carbamate. Allyl carbamate has the formula
,0, / H
CH2=CH-CH2-0-C-N ~ ' :
This monoethylenic monomer is not an amide and it will react
with formaldehyde in an addition reaction with the two amino hydrogen
atoms to generate the N-methylol group. When one molar proportion of
formaldehyde is taken up, the derivative can be described by the formula
O / H
CH2=cH-cH2-o-c-N
CH2H
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The s~me reaction can proceed to tak~ up more
formaldehyde to increase the N-methylol functionality ~hich
is generated.
Regardless of whether one or two moles of for~alde-
hyde are reacted into the molecule, the monomer is an allyl
ester and this is most important in the copolymerization with
vinyl halide, since the monomer reactivity ratio of the allylic
~nsaturation of the allyl ester with vinyl halide is close to
1:1. In contrast, methylol acrylami.de enters thc vinyl
halide copolymer much too rapidly, forcing a considerable
portion of the polymer to lack the reactive group which is
the basis for subsequent insolubili~ation~
The emulsion copolymerization is also improved
herein by the increased hydrophobicity conferred by the
allyl group creating a synergis~ic improvement in the capacity
of the copolymer to become insolubilized on curing. Such
hydrophobicity can also be enhanced by employing an ether group,
as will be explained.
As previously indicated, the allyl carbamate may
include ether groups between the allyl group and the carbama~e
group. These ethers can be provided by reacting the allyl
alcohol with an al~ylene oxide, such as ethylene oxide before
converting the resulting alcohol to the carbamate as will be
illustrated hereinarter.
The adduction of the carbamate with formald~hyde is
~ell known and conventional and yields N-methylol d~rivatives.
These are a mixture of the mono-N-methylol adduct, the di-N-
methylol adduct and unreacted carbamate which, if present, is
not ha~mful.
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The N-methylol groups in this invention may be
etherified with a Cl - C8 alcohol, preferably a Cl - C4
alcohol, though this is not essential. The alcohol is
released on baking to regenerate the N-methylol group for
cure, as is well known. Appropriate alcohols for etherifi-
cation are methyl alcohol and ethyl alcohol. Isopropyl
alcohol, isobutyl alcohol, 2-ethoxy ethanol and 2-butoxy
ethanol will further illustrate useful alcohols.
The invention is applicable to vinyl halides.
Among the halides, the chlorides are most commonly avail-
able, and are most economical so that this invention is
primarily addressed to the use of vinyl chloride. On the
other hand, the corresponding bromides introduce superior
fire resistance and, when this characteristic is important,
the bromides may be used. Similarly, the corresponding
fluorides provide polymers which are very inert and, when
it is desired to obtain maximum corrosion resistance and ~ .
durability, the corresponding fluorides may be used. The
iodides are also subject to use in this invention, but these ~ ~-
would only be used to provide special properties. Of course,
the different halides are also useful in admixture.
Also, and while copolymers with ethylene are
especially important, the invention includes copolymers
in which the ethylene is partially replaced with a mono-
ethylenic carboxylic acid ester which provides the desired
internal plasticization. The ester group will contain a
terminal saturated hydrocarbon group having at least 2 carbon
atoms, preferably at least 4 carbon atoms, and is usually an
alkyl ester of an alpha,beta-ethylenically unsaturated acid
such as maleic acid, fumaric acid, acrylic acid, crotonic acid,
itaconic acid, and the like. These are illustrated by butyl
acrylate, diethyl maleate, and isooctyl crotonate. Other
esters such as vinyl hexoate are also useful, though less
preferred. The ester group may contain up to about 18 carbon
atoms.
From the standpoint of proportions, the vinyl
halide will constitute from 35-96.5% of the copolymer, pre-
ferably 45-75%. The ethylene component will constitute from
3-60%, preferably from 10-45%, and most preferably from
20-40%. Of course, mixtures of ethylene and ester in the
same total amount can be used.
The monomers providing thermosetting or cure capacity
may be used in an amount of from 0.5-15%, preferably 2-10%,
based on the weight of the copolymer. At least 0.5%, prefer-
ably at least 1%, based on the weight of the copolymer, will
be constituted by the formaldehyde addition product with the
allyl carbamate compound, preferably from 1% to 8%. However,
other monomers which can coreact with the N-methylol group -
may also be present to assist in the cure, such as monoethylenic
amides or alcohols, either alone or together with one another
or with a monoethylenic carboxylic acid.
The coreactive monomers are illustrated by acryl-
amide, methacrylamide, or other monoethylenic amide, or by
allyl alcohol, 2-hydroxy ethyl acrylate or methacrylate, or
the like. Monoethylenic carboxylic acids are illustrated by
acrylic acid, methacrylic acid, and crotonic acid. These acids
are used in an amount of from 0.5-3%.
Other monomers which may be present in an amount up
to about 20% of the copolymer are illustrated by acrylonitrile,
methyl methacrylate, styrene, or vinyl acetate.
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Since the aqueous emulsion polymerization of vinyl
chloride either alone or with ethylene or esters such as
butyl acrylate is well known per se, it will not be described
at length. However, it is stressed that the N-methylol allyl
carbamate is easier to use since it will enter the copolymer
at about the same rate as the vinyl halide so that the
distribution of the N-methylol group in the final copolymer
is considerably improved. Auxiliary agents may also be present,
as is known, such as protective colloids, illustrated by poly-
vinyl alcohol and hydroxy ethyl cellulose.
From the standpoint of cure, baking is normally
carried out at temperatures of from 250-500F. for periods
of from 30 seconds to 1 hour, but more usually at 275-350F.
for from 2-20 minutes.
The proportions referred to herein and throughout
this specification are by weight unless otherwise specified.
Example 1
Monomer Emulsion (100% charged) Parts
Vinyl Chloride tDistilled) 12000 grams
Sodium Lauryl Sulfate (30% water Solution) 1695 "
Dioctyl Ester of Sodium Sulfo Succinic Acid
in a 60% Water Solution 847 "
Acrylamide (16.9% in Water) 2600 "
N-Methylol Allyl Carbamate (16.9% in Water) 2600 "
A stainless steel pressure reactor equipped with
temperature controls and an agitator was charged with:
Charge Parts
Water 10400 grams
Sodium Lauryl Sulfate (30% Water Solution) 565 "
Dioctyl Ester of Sodium Sulfo-succinic Acid
in a 60% Water Solution 282 "
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Charge and Parts (continued)
Previously Prepared Seed Polymer Emulsion
at 45% Total Solids (Use previous batch
of this Example or commercial polyvinyl
chloride of particle size .15 micron) 760 grams
Ferrous Sulfate 0.15 "
Maleic Anhydride ~5 "
Monomer Emulsion of this Example 1850 "
Sodium Persulfate 55 "
The reactor was purged with nitrogen, then with
ethylene, after which the reactor was pressurized to 60
atmospheres with ethylene. After heating the reactor mixture
to 50C., 5cc of a 6% water solution of sodium formaldehyde
sulfoxylate were added, after which the reactor temperature
rose to 53C. The remaining monomer emulsion (to 100% of
the total amount prepared) was added continuously over a five
hour period. The reaction temperature was maintained exothermic
by incremental additions of a totalamount of 195cc of a 6%
sodium formaldehyde sulfoxylate solution, and 750cc of a
10% sodium persulfate solution. The ethylene pressure was
maintained at 60 atmospheres during most of the run, and then
the ethylene pressure was slowly reduced to atmospheric pressure,
and the pH was adjusted to 5.3 with ammonia.
The product had the following properties:
Viscosity (#3 spindle, 30 rpm Brookfield) 1000
Solids 37.5%
Intrinsic Viscosity (measured in 1%
dimethyl formamide at 30C. and
extrapolated to 0%) 1.24
Insolubles
at pH 2.7 55.1%
at pH 8.0 52.8%
pH 5.2
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Average Particle Size 0.225 micron
Ethylene in Copolymer 45%
Example 2
Example 1 was repeated, replacing the N-methylol
allyl carbamate with a corresponding weight of N-ethoxy
methyl allyl carbamate. The final produced cured to provide
even better insolubility~
