Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to quaternary copolymers
containing ethylene as the main constituent. Combined
with the ethylene are an ester of an unsaturated carboxylic
acid and a saturated alcohol or a vinyl ester of a saturated
carboxylic acid, the amide of an unsaturated carboxylic
acid, and an alkyl vinyl ether.
German published Patent Application DAS 1,645,018
describes the copolymerization of ethylene with tert-
butylamino ethyl methacrylate or an ester of an unsatura-
ted carboxylic acid, and the amide of an unsaturated
carboxylic acid to produce copolymers useful for the pro-
duction of hollow-shaped articles and film. These articles
can be produced by the usual methods, such as casting, ex-
trusion and injection molding.
. -2-
:1~50363
German published Patent Application DAS 1,645,024
relates to a process for producing ethylene copolymers con-
taining from 1-10 mole percent of a vinyl ether, from 0.5-20
mole percent o~ unsubstituted acryl or methacrylamides and
70-98.5 mole percent of ethylene.
German Patent Application P 24 00 978.7 of the
present inventors, which has not yet been published, teaches
a process for bonding together or coating materials using
as an adhesive or coating composition, an olefin copolymer.
This copolymPr contains 70-90 parts of ethylene, ~.5-10
parts of the amide of an e~hy~enically unsaturated carboxylic
acid and 0.5-20 parts of the ester of an ethylenically un-
saturated carboxylic acid. When producing polymers having
the~oomposition mentioned above,it is necessary, to achieve
commercially useful melt flow indices, to maintain high
modifier concentrations. For example, the polymerization
is ef~ected in the presence of 10-12 percent of propane
as a modifying ingredient. This percentage is based on the
weight of ethylene. This substantial dilution of the
ethylene results in a marked reduction in conversion. Such
high concentrations of modifier are not necessary in the
process according to the present invention because the
vinyl ether has a molecular weight-controlling action. In
addition, the adhesive properties of these polymers are
largely dependent upon their composition. Maximum adhesive
strength is achieved only within a very narrow concentration
--3--
~ 50363
range of the comonomers. Therefore, it is necessary when
producing the polymer that the individual components are
maintained in the precise proportion requi.red.
The prior art also shows the use of binary and
tertiary ethylene copolymers containing acrylic acid for
bonding and coating various materials and substrates.
These high molecular weight compounds also exhibit inherent
deficiencies which are due to the presence of carboxyl
groups in the macromolecule. Because of the formation
of hydrogen bridges, the carboxyl groups favor the accumu-
lation of water between the coating and the substrate.
This results in delamination and detachment of the polymer
from the substrate. This phenomenon is particularly serious
in cases in which the bonding m~çhanism is based on the
carbo~lic acid groups of the adhesion promoter; for example,
when the copolymers adhere to metals.
It has now been found that the deficiencies and
disadvantages mentioned above are not exhibited by the quat-
ernary copolymers o~ the present invention. These copolymers
consis~ of 70-90 parts of ethylene, 0.5-15 parts of an
alkyl ester (wherein the alkyl group contains up to 8 carbon
atoms) of an unsaturated monocarboxylic acid having 3-6
carbon atoms or the vinyl ester of a saturated monocarboxylic
acid having up to 3 carbon atoms, 0.5-10 parts of an amide
of an unsaturated monocarboxylic acid having 3-6 carbon
atoms, and 0.1-5 parts of a vinyl ether having up to 10
carbon atoms; the sum of the parts totalling 100
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~LOS~363
It is a preferred embodlment of this invention
that the quaternary copolymers contain 80-90 parts of ethy-
lene, 7-12 parts of an alkyl ester (wherein the alkyl group
contains up to 8 carbon!atoms) oE an unsaturated monocarboxy-
lic acid or a vinyl es~er of a sa~urated monocarboxylic acid
having up to 3 carbon atoms, 5-8 parts of an amide of an
unsaturated carboxylic acid having 3-6 carbon atoms and
0.1-1 part of an aliphatic or aromatic vinyl ether having up
to 10 carbon atoms; the sum of the parts totalling 100.-
The above-mentioned quaternary copolymers are
characterized by crystalline melting points of 95C.-100C.
and densities of 0.925-0.938, measured acco~ding to DIN 53 479.
Products having melt flow index values of 0.1-100, especially
those having melt flow index values between 1 and 50 are
suitable as adhesives. As compared with terpolymers of
ethylene, acrylic acid and acrylic acid esters, the quater-
nary copolymers have a higher modulus of elasticity.
Examples of esters of unsaturated carboxylic acids
which may be used as comonomers include ethyl acrylate,
n-propyl acrylate, n-butyl acrylate, tert-butyl acrylate,
t~rt-butyl methacrylate, tert-butyl crotonate, and 2-ethyl
hexyl acrylate. Particularly suitable are the es~ers of
acrylic and methacrylic acids with tert-butanol and tert-
amyl alcohol. Vinyl acetate is representative of the vinyl
esters of saturated carboxylic acids.
For the purposes of this invention, acrylamide,
methacrylamide and crotonic acid amide are the preferred
i~5~363
amides of unsaturated carboxylic a~ids.
Examples of copolymerizable ethers include methyl
~inyl ether, ethyl vinyl ether, propyl vinyl ether, i-butyl
vinyl etherS and n-butyl vinyl ether. The type of the ether
used does not affect the adhesiveness of the copolymer.
The copolymers according to the present invention
are produced at pressures of 400 to 4,000 bars and ~empera-
tures of 100C. to 350C. The polymerization is carried
out in the presence of catalytic quantiti~s of free radical
initiators (e.g. oxygen, in amounts of 2 to 250 molar parts
per million parts of ethylene). Furthermore, peroxides and
other free radical forming substances, such as tert-butyl
perbenzoate, dilauryl peroxide, didecanoyl peroxide, di-tert-
butyl peroxide, azoisobutyrodinitrile may be used alone or
in mixture in amounts of 2 to 200 molar parts per million
parts of ethylene. The polymerization may be effec~ed in
the presence of modifying ingredients such as aliphatic
alcohols, aliphatic saturated carbonyl compounds, chlorinated
hydrocarbons and hydrogen. The process according to this
invention may be effected either continuously or batch-
wise; the continuous operation is preferred. When operating
continuously, the copolymer is withdrawn ~r~m the reactor.
The unreacted portion of the monomers, the initiator and
the modifying ingredients are then recycled.
The quaternary copolymers prepared according to
the present invention, which contain 0.1 to 1.0% of an alkyl
~(~5~336~
vinyl ether, exhibit excellent adhesive strength on various
substrates such as metals and woods. This adhesive strength
is maintained at a high level regardless of the ratio of
the other comonomers.
The copolymers strongly adhere to the substrate
as coatings, impregnations and surface layers, especially
if applied in the molten state. The copolymers may be used
in this manner as thermal plastic adhesives for metalsg
ceramic materials, paper, textiles, wood, glass, leather
and plastic materials.
~ue to the presence of hydrophilic amide groups,
~he quaternary polymers may also be processed to produce
stable emulsions which permit the use of the polymers in
~inely divided form. When used in the form of emulsions
and solutions of the copolymers, it is possible to produce
very thin films on metals, ceramic materials, glass, tex-
~iles, wood, paper, leather, and plastic materials These
films are useful as adhesives for lamination with polyole-
fins such as polyethylene or rubber.
A surprising result of the present invention is
that a smaller amount of an alkyl ester of an unsaturated
carboxylic acid is needed than that which would be ex-
pected to obtain satisfactory adhesive strength. This
result is shown even when the copolymer contains only a
small amount of an alkyl ether.
~1~50363
The polymers or the materials that are impreg-
nated with the polymers can be printed. Their affinity
with dyes is remarkable. In addition, the copolymers are
useful as additives in coating compositions, especially
those polymers which con~ain a relatively high proportion
of copolymerized comonomers.
The following examples illustrate the production
of the new polymers and their use for bonding or coating
substrates and materials In these examples, parts and
percentages are by weight unless otherwis~ stated.
A. Production of the polymers
The quaternary copolymers are produced in a con-
tinuously operated laboratory autoclave unit, comprising
an autoclave equipped with a magnetic stirrer and an
electrical heater. Before it is introduced into the auto-
clave, the ethylene is mixed with gaseous additives such
as oxygen as an initiator and, if necessary or desired,
propane as a modifier. The mixture is then compressed
to the reaction pressure. The reaction mixture is then
passed through a preheater and into the autoclave. At
~he same time, the comonomers, if necessary, are dissolved
or diluted and are then fed into the reactor by means
o two high pressure metering pumps having different
delîveries. Low molecular weight polar organic compounds
such as methanol, ethanol and butanol have been found
~ ~S~ 3 ~ 3
to be particularly useful solvents. The polymerization
is effected at temperatures between 170C. and 280C.
The~polymer-monomer mixture leaving the reactor is de-
pressurized to about 2 to 3 bars by means of a cont~ol
valve. In doing so, the polymer formed is separated and
collected in alternately filled receivers.
B. Determination of adhesive strength
Cleaned aluminum strips o 100 mm. in length,
100 mm. in width and 1.5 mm. in thickness were bonded to-
gether by pressing (pressure, 3 kgs./sq.cm.; pressing time,
30 to 40 seconds; compression temperature 180C.) over a
length of 70 mm. by means of films consisting of the
particular ethylene copolymers and produced by compression
or e~trusion through a slot die. In another experiment9
aluminum strips having the same dimensions were bonded
under the same conditions to a sheet of high pressure poly-
ethylene of 4 mm. thickness. The unbonded lengths of the
aluminum strips were bent at right angles in opposite
dire~tions.
The adhesive properties are primarily demonstrated
by the peel strength. This value represents the force
per tear length which is necessary to braak the bond. With
respect to the adhesive property, it is necessary to dif-
ferentiate between the force required to initiate peeling
and the force required to maintain peeling per tear length.
~ OS0363
The force to maintain peeling is important in determining
the adhesive strength of ~he product being tested.
The physical data mentioned above is de~ermined
by means of a tensile tester. Metal sheets (30 mm. by
100 mm.) are bent at an angle and are placed in the
grippers of the testing machine in such a manner th~t the
adhesive coated surface (70 mm. by 100 mm.) extends at
right angles with respect to grippers. The system is
pulled apart at a rate of 50 mm./minute. At the same time,
the tearing forces which are characteristic of the strength
properties are recorded.
Example ~
A reaction mixture consisting of 97.62% of
ethylene, 1.12% of acrylamide, 1.12% of tert-butyl acrylate,
and 0.14% of isobutyl vinyl ether and compressed to 1~-900
atm. is continuously fed into the inlet of the reactor
described above. The polymerization is effected in the
presence of S molar parts of oxygen per million parts of
ethylene at a reaction termperature of 249C. After a
residence time of 55 seconds of the reaction mixture in
the reactor, the copolymer is discharged. An overall
8.1% conversion to polymer is obtained. The polymer con-
tains 84.14% of ethylene, 7.7% of acrylamide, 8.0% of
tert-butyl acrylate, and 0.16% of isobutyl vinyl ether
in copolymerized form.
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~ ~5~3~ 3
The melt flow index (MFI 190/2) is 4Ø
The adhesive properties of the product are de-
termined by the method described above. The peel strengths
are as follows:
Force to initiate peeling 10.0 kgs./cm.
Force to maintain peeling 3.0 kgs./cm.
~.
As described in Example l, a reaction mixture
consisting of 98.0% of ethylene, 1.05% of acrylamide,
0.38% of tert-butyl acrylate, and 0.24% of n-butyl vinyl
ether is continuously fed into the reactor and compressed
to 2,200 atm. The polymerization is effected at 245C. and
in the presence of 3 molar parts of oxygen per million
parts of ethylene. An overall 8.3% conversion to polymer
is obtained. The copolymer consists of 85.4% ethylene,
7.7% of acrylamide, 6.7% of tert-butyl acrylate, and 0.2%~
of n-butyl vinyl ether. The melt flow index of the product
is 1.3. The peel strengths are as follows:
Force to initiate peeling 7O4 kgs./cm.
Force to maintain peeling 2.6 kgs./cm.
Example 3
A reaction mixture consisting of 97.6% of ethylene,
0 97% of acrylamide, 0.97% of tert-butyl acrylate, and
0.46% of e~hyl vinyl ether and compressed to 2~250 atm.
is introduced into the reactor at a temperature of 252C
and in the presence of 6 molar parts of oxygen per million
~050363
par~s of ethylene, the residence time of the reaction
mixture in the reactor being 56 seconds. A copolymer
consisting of 86.2% of ethylene, 7.3% of tert-butyl
acrylate, 6.0% of acrylamide, and 0.5% ethyl vinyl ether
i~ obtained with an 7.9% overall conversion.
The polymer has a melt flow ind~ (MFI 190/2)
of 6.5, a density of 0.926 and a crystalline melting point
of 98C. The va-~ues measured for Shore A and D hardness
are 87 and 40, respectively.
The peel strengths are as follows:
Force to initiate peeling 13.6 kgs./cm.
Force to maintain peeling 2.9 kgs./cm.
Example 4
A reaction mixture consisting of 97.84% of
ethylene, 0.96% of acrylamide, 0.96% of term-amyl acrylate,
and 0.24% of n-butyl vinyl ether are introduced into the
reactor. Polymerization is ef~ected undar a pressure of
1,900 a~m., in the presence of 3 molar parts of oxygen
per million parts of e~hylene are used as an initiator and
1.5 molar parts of propane per 100 parts of ethylene as a
polymerization controlling agent. After a residence time
of 54 seconds o the reaction mixture in the reactor, a
copolymer consisting of 87.4% of ethylene, 5.8% of acryl-
amide, 6.6% of ~ert-amyl acrylate, and 0.2% of n-bu~yl
vinyl ether is obtained, the conversion to polymer being
8.3%. The melt flow index is 6Ø The peel strengths
are as follows:
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~()S~)363
Force to initiate peeling 13.1 kgs./cm.
Force to maintain peeling 2.4 kgs./cm.
Example 5
A reaction mixture consisting of 97.7% of ethylene,
0 92% of acrylamide, 0.92% of n-butyl acrylate, and 0.47%
of n-butyl vinyl ether is introduc:ed into the reactor. The
polymerization is effected under a pressure of 2,200 atm.
The initiator concentration is 4 molar parts oxygen per
million parts of ethylene and the reaction temperature is
242C After a residence time of 53 seconds in the reactor,
a copolymer consisting of 86.9% ethylene, 5.6% of acryl-
amide, 7.0% of n-butyl acrylate, and 0.5% of n-butyl vinyl
ether in copolymerized form is obtained. The overall con-
version amounts to 8.9%. The melt flow index is 5.1. The
peel strengths are as follows:
Force to initiate peeling 10.0 kgs./cm.
Force to maintain peeling 2.5 kgs./cm.
Example 6
A reaction mixture of 91.3% of ethylene, 1.0%
of methacrylamide, 7.0% of vinyl acetate, and 0.3% of iso-
butyl vinyl ether is ed into the polymerization reactor,
in the presence o~ 6 molar parts of oxygen per million
parts of ethylene as the polymerization initiator, the
resulting reaction mixture being continuously discharged.
The pressurP in the reactor is 2,000 atm. and the tempera-
ture is 252C After a reaction time of one hour 1150 g
363
of copolymer consisting 85.7% ethylene, 6.9% methacryl-
amide, 7.1% of vinyl aceta~e3 and 0.3% of i-butyl vinyl
ether in copolymerized form is obt:ained, the conversion
being 8.1%. The melt flow index is 43. The peel strengths
are as follows:
Force to initiate peeling 8.3 kgs./cm.
Force to maintain peeling 2.1 kgs./cm.
Comparative Example 1
The procedure is as described in Example 1 thrDugh
6, except that the polymerization is effected in the absence
of esters of unsaturated carboxylic acid and vinyl ether,
a reaction mix~ure of 99.0% of e~hylene and 1% of acryl-
amide is polymerized. A copolymer consisting of 91.9% of
e~hylene and 8.1% of acrylamide in copolymerized form is
obtained, the conversion to polymer being 8.2%. The melt
flow index is 0.1. The peel strengths are as follows:
Force to initiate peeling 3.2 kgs,/cm.
Force to maintain peeling 0.5 kgs./cm.
Camparative Example 2
The procedure is as described in Examples 1
- through 6, except that the polymerization is conduc~ed
with a reaction mixture of 97.6% of ethylene and 2.4% of
n-butyl acrylate. The resultant copolymer consists of
84% of ethylene and 16% of n-butyl acrylate in copoly-
merized form. The product has a melt flow index of 1.9
and no adhesion.
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3~3
Comparative Example 3
The procedure is as described in Examples 1
through 6, except that ethylene is polymerized with acryl-
amide and vinyl isobutyl ether in a 7.8% overall yield.
The resultant ethylene copolymer consists of 92.9% ethylene,
6.1% of acrylamide, and 1.0% of vinyl isobutyl ether in
copolymerized form. The melt flow index is 1Ø The
peel strengths are as follows:
Force to initiate peeling 3.8 kgs./cm.
Force to maintain peeling O.S kgs./cm.
Comparative Examples 4 throu~h 9
The polymerizations are effected by the procedure
described in Examples 1 through 6. The comonomer concentra-
tions in the starting reaction mixtures are selected so that
the resultant copolymers consist of 79 to 85% ethylene, 6
to 8% of acrylamide and 8.6, 9.0, 9.7, 11.1 and 13.6% of
n-butyl acrylate or tert-butyl acrylate. The melt flow
index values are 0.9, 0.7, 0.3, 9.8, 3.5, 4.4, respectively.
The measured pee-l strengths are ~hown in Table 1. It is
clear that terpolymers having an acrylamide content in the
range from 6 to 8% give optimum peeling strengths if the
copolymer cantains approximately 9 to 12% of acrylic acid
ester. If 0.1 to 0.5% by weight of alkyl vinyl ether is
incorporated into the polymer, only 7 to 8% of acrylic
acid ester is necessary to achieve the same peel strength.
~15-
363
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