CA1069925A - Process for the preparation of low molecular weight ethylene/vinyl acetate copolymers - Google Patents

Process for the preparation of low molecular weight ethylene/vinyl acetate copolymers

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Publication number
CA1069925A
CA1069925A CA232,723A CA232723A CA1069925A CA 1069925 A CA1069925 A CA 1069925A CA 232723 A CA232723 A CA 232723A CA 1069925 A CA1069925 A CA 1069925A
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Canada
Prior art keywords
vinyl acetate
ethylene
weight
molecular weight
polymerisation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA232,723A
Other languages
French (fr)
Inventor
Herbert Bartl
Raoul Resz
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Bayer AG
Original Assignee
Bayer AG
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    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08FMACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F210/00Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
    • C08F210/02Ethene

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Abstract

Abstract of the Disclosure A process for the production of an ethylene/vinylester copolymer having a molecular weight of from 500 to 10,000, and intrinsic viscosity numbers of 0.1 to 0.5 dl/g, determined in p-xylene at 25°C, wherein ethylene and vinyl ester are poly-merised radically at a temperature of from 10 to 200°C and a pressure of from 10-700 bars in the presence of from 0.2 to 5 %
by weight of acetaldehyde, based on the quantity of the initial monomers.

Description

%5 This invention relat~s to a proce~ for the preparation o~
ethylene/vinyl acetate copolymers which have molecular weights o~
between 500 and 10,000.
Processes for the preparatlon of copolymers of ethylene and vinyl acetate which have molecular weights o~ from 1,000 to 3 9 000 wherein the monomers are polym~rised at temperatures of about 138 to 171C and pressures of 48 to 136 bars in a b~nzene polymerisation medium and in the presence of radical polymerisa-tion initiators have already been disclosed in DT-AS No. 1,147,79 and in U.S. Patent Speci~ications Nos. 3~093,623, 3,126,364, 3,131,168, 3,159~608, 3,254,063 and ~,627,838. These copolymers are used as addîtives ~or hydrocarbon propellents or fuels which have boiling ranges between about 120 and 400C to lower their pour point and make them easier to filter~ The processes described in the above mentioned Patent Speoification~ have ~umerous disad-vantages. The copolymeri~ation mw3t be carried out at high tempe-ratures 9 nam~ly above 100C~ and in the presence o~ a relatively large quantity o~ polymerisation inlti~tor 9 namely 2 to 5 % by weight, based on the amount o~ copolymer obtained in order to obtain sufiiciently low molecular weights.
- The use o~ physiologically harm~ul benzene solvent as poly-merisation medium requires the use of special protective devices to remov~ the solvent vapours duri~g isolation o~ the copolymer.
Another disadYantage o~ the processes m~ntioned above is that they can only be carried out in speclal apparatus and not in the usual plants used for the manu~acture of high molecular weight ethylene/vinyl acetate copolymers.
In the German O~fenlegungsschri~t No. 2,102,469 a process for the preparation o~ low molecular weight ethylene¦vinyl ace-tate copolymers by a high pressure polymerisation process in Le A 15 880 ~6g~

the presence of regulators which have transfer constant Cs grea-ter than 10 2, determined ~or ethylena at 130C and 1360 bars, and in the absence of solvents ha~ been disclosed. This process requires a polymerisation plant in which polymerisation can be carried out at pressures above 1000 bars or ther~abouts.
It has also been disclosed in the German Auslegeschrift No.
1,126,613 that high mo~ecular weight copolymers containing up to ~5 % by weight o~ vinyl esters can be obtained by the polymerisa-tion o~ ethylene and vinyl acetate at presqures above~10 bars and pre~erably at 100 to 200 bars in a liquid phase which consiæts predominantly of tertiary butanol and may contain 0 to 20 % by weight of water. The copolymers obtained by this process have mo-lecular weights substantially above 10~000 and their ~iscosity determined in p-xylene is substant:Lally above 0.5 dl/g.
A process has no~ been found ~or tha preparation of ethylene/
vinyl acetate copolymers having mo:Lecular weights of ~rom 500 to 10,000 and intrin~ic viscosities d~termlned in p-xylene at ~5C
o~ ~rom 0.1 to 0,5 dl/g, by polymerisation of ethylene and vinyl acetate in molar ratios o~ between 20 : 1 and 1 : 1 in the pre-sence of radical polymerisation initiators at temperatures of from 10 to 200C, pre~erably 30 to 150C and at pressures of 10 to 700 bar, pre~erably 50 to 5Q0 bar, wherein the polymerisation of ethylene and vinyl acetate is carried out in a reaction medium consisting predominantly of tertiary butanol in the presence of 0,2 to 5 % by weight~ pre~erably 0.5 to 4 % by weight of acetalde hyde, based on the quantity of the monomers.
Ethylene/vinyl acetate copolymers can be obtained having any desired molecular weight between 500 and 10,000 by the inven-tive process by the addition o~ relatively small quantities of acetaldehyde. A considerable proportion o~ the added acetaldehyde ~ L~ 2 -91Z~

is copolymerised during polymerisation so that the mixture o~ sol vent and monomer recovered a~ter isolation of the polymer contalns only small quantities of acetaldehyde. In contra3t to numerous other kno~n molecular w~ight regulators which might also be used9 the acetaldehyde in the solvent~monomer mixture can, i~ necessary, be removed to a large extent, for example by ~raotional distilla-tion. The residual mixture thus obtained may be then used for the ` preparation of high molecular weigh-t ethylene/vinyl acetate co-polymers.
It is surprising to find that acetaldeh~de is a suitable mo-lecular weight regulator ~or the preparation of the copolymers ; according to the invention sincè it is known ~rom ~erman Auslege-schrift No. 17745~570 (= British patent ~pecification No. 1,226,167) that the addition of acetaldehyde to the copolymerisation of ethy-lene and vinyl acetate results in cross-linked and there~ore in-completely soluble productR~ Moreover9 it has been disclosed in German Auslege~chri~t NoO 1,955,471 (= US-patent pecification No.
3,506,630) that acetaldehyde is unsuitabl~ ~or use as polymerisa-tion regulator on account of its tendency to ~orm paraldehyde.
Additionally the u~e o~ tertiary butanol as preferred poly-~; merisation medium, which has a v~ry ~eak regulating action, and acetaldehyde, which is a power~ul regulator and easily removed, ;~ enables the production o~ ethylene/vinyl acetate copolymers with very varying degrees o~ polymerisation in one and the same poly-merisation plant while the residual monomer/solvent mixture con tinuously obtained from i olatlon o~ the product can be retùrned to the polymerisation proress.
Although vinyl acetate may be partly or completely rsplaced by vinyl esters of other aliphatic or aromatic carboxylic acids having 3 to 20 carbon atoms in the proce~s according to the in-Le A 1~_~80 3 -ii9~25 vention, e.g. vinyl propionate J vinyl butyrate, vinyl pivalate, vinyl laurate or vinyl benzoate, vinyl acetate is preferably used.
The ratio of the copol~mers may vary within wide limits. If a molar ratio of ethylene to vinyl ester of between 20 : 1 and 1 : 1 is used, for example, the quantity of vinyl acetate incorporated in the ethylene/vinyl acetate copolymer is 13 to 75 % by weight.
The radical polymerisation initiators used may be a~o com-pounds, e.g. bis-azo-butyric acid nitrile~ or organoperoxides or hydroperoxides such as lauroyl peroxide, di-tert.-butylperoxide, benzoyl peroxide or tert.-butylhydroperoxide. They are pre~erably used in quantities of 0.1 to 1 % by weight, based on the quantity o~ monomers used.
By carrying out the polymerisation in tertiary butanol as the pre~erred polymerisation medium7 it is possible to use rela-ti~ely low pressures of from 10 to 500 bars. The polymerisation temperature employed is preferably betw~en 30 and 150C, accordlng to the decomposition point o~ the polymerisation initiator usedO
The polymerisation proces~ may be carried out either discontinuous~
ly or continuously in several polymerisation autoclaves arranged in series or in a tubular reactor. The quantity of acetaldehydeused QS regulator is adju~ted to the desired molecular weight. In order to obtain molecular weights in the region of ~rom 500 to 10,000, for example, it ls ne~essary to use 0~2 to 5 % by weight, preferably 0.5 to 4 % by weight of acetaldehyde, based on the quantity of monomers used The molecular weight Mn is d~termined in a Meckrolab apparatus (see HG. Elias~ Makromolekule, 2nd Edition, 1972, page 237), pre~erably by the vapour pressure osmometric method of the polymer solution in toluene~
The low molecu~ar weight ethylene/vinyl acetate copolymers prepared according to the lnventIon may be used as adhesives or Le A 15 880 - 4 -~t6g~25 `

adhesive components. Copolymers which contain ethylene and vinyl ace~ate in molar ratios of from 10 : 1 to 5 : 1 and which have molecular weights in the range of 500 to 300, respectively intrinsic ~iscosities in the range of from 0.1 to 0.25 dl/g are added in amoun~s of from 0.01 to 0.5 %
~y~ weight to various mineral oil ractions, particularly to the so-called middle distillates which have boiling points of from 120 to 400C, to lower their pour point and/or im- ;
prove their ability to be filtered. To prepare these co- ^
polymers, 1 to 4 % by weight acetaldehyde, based on the quantity of monomers used, is preferably added to the monomers. Another wide field of application which is available to these copolymers is their use as plasticizers ~;
~or various polymers, particularly for polymers which ha~e a high chlorine content such as polyvinyl chloride, re-; chlorinated polyethylene and chlorine rubber as well as ~ cellulose esters, polymethacrylic acid esters. The ; saponification products of these copolymers as well astheir reaction products with compounds which are capable o~ reacting wlth hydroxyl groups, such as isocyanates, acid anhydrides, acid chlorides, aldehydes~ ketones or epoxides, ma~ also be used in various fields, for example for the production of lacquers or adhesives and as plasti-cizers.

9L~6~

A mixture of 8000 g o~ terti~ry butanol~ 2000 g of vinyl ace$~te~ 200 g of acetal~ehyde and 40 g o~ bis-azo-butyric acid nitrile is introduced into an autoclave which has a capacity of 30 litres. The ~ir is expelled ~om the autoclave by nitrogenj and 6000 g of ethylene are forced in under pre~sure ~rom a steel cylinder. The autoclave is then heated with stirring~ ~ir~t to 650C i~or 3 hours, then to 70C for 3 hours and finally to 80C for 6 hours. The pressure -~ir~t rises to 220 ba~ and then drop~ to 8~ bar~
during polymerisationO The autoclave contents are then cooled to 20C and the pre~sure is released. 12300 g o~
a 34,7~ by weight solution oi th~e polymer are obtained.
The polymer is isolated by removal of the volatile constituents under vacuum. 4300 g o~ a viscous ma~
which solidi~ied on cooling wa~ obtained. The ~u~nt~ty of vinyl acetate lncorporated in the copolymer9 whlch wa~
determined by the saponification number~ 28.2~ by weighte The intrin~ic vi~oosity (~) determined in p-xylene at 25G~ is iound to be 0~17 dl/g.j The molecular weight of the product9 determined by vapour preæsure osmometry in toluene, is 2580.

; Other low moIecular weight ethylene/vinyl acetate copolymer~ having ~arying compo3ition~ and molecular weight~
are prepared with di~erent ~onomer r~tios ~nd di~ferent additions of acetaldehyde by the proce~s described in Example 1. The relatiYe dAta o~ these example~ are given in the enclo~ed Table l. The intrinsic viscoslti,e6 and molecular weights ar~ determi~ed a~ indicated in Example 1 :... , , .,. : ,.~ . .. .. .

~69~2S
r~
~ o O O O O ~ u~ o u~ ~ o o o U~ U~ ~ ~ , ~ ~ . . .
~ o ~ o o e~ o U~
~ u~ 1 ~
o o o o or~ ~ ~ . . ~ o o o o ~ o U~ ~ o o o o ~ ~ ~ U~
~D ~ ~
. ;i, ~ o oooooU~ ~o,,~
0 o o o ~ o . ~ ~ . . . Cr~
o o o ~ ~ ~ ~ o (~D ;I' :r ~ .
~ C\~ 0 ,~ ~o '' OOOOOt~I~U~ .. . O
1~ ~ ~
O C~l ~D
0 ~ ~
U~ o o o o o o U~ C~l o C~lU~ ,, , ~D O O O~ O I`~D
o c~ I~ ~ OC~
0 ~ ~ ~ ;r o o o o o oU~ C`l oo o ~ ~ ~
u~ o o o ~ o . I` u~. . .1--O ~) O C`l C`l ~ C`l O C~
0 ~ U~ ~ ~

Il~ O OO~ N
ooooo~) t~ .. . ao o o o ~r o o ~o o ,~, o :r ~o ~ ~ ~ ~
0 C`l q~
D O
E~ O O C~ O O~ ~ C`l ao o ~ ~1 t~'\ O O ;t~ O r- ~ a ;p O ~ ~ ~ ~ a~ r- o C~l U~ ~ ~
O
~ O
O O O ~ O U~ O ~ O~
c~lo o o ~ c~
O ~ ~ ~ ~ `D O
0 ~ ~ ~ r~
_ .bO

~R
bD bO t~
_' _ ~ ~ ~ o a~

~I O O O ~~
h D~ _ h ~ _ ~
o ~ .,, ,~, h~ O ~ ~ 0 ~ ~ ~
h o o ;1: 0 ,q ~ rl ~ ~ ~ ~ 0 h 60 r r-~ ~ Ra 0 ,Q c~ rl . 0 0 0~ ~ ~ 9 o ~ ~ 0 ~ C~ 0 I~ f:; h O o ~ 0 0 1 ~ 1 0 ~ O ~ 0~11 ~ O ~ h G~ ~1 r~ ,~ ~) N ~1 ~ 0 : G~
a ~ h ~ O
~ ~ q a o P~ a~
~ ~ ~ rlO ~ O ~ O ~ O ~ O
C~ ~ ~ ~ ~ ~ ~ 0 ~ ~ ~ C~
Le A 15 8~0 7_ - ~6~9 ~a~
A mi~ture of 59.5 kg o~ tert.-but~nol, 26.8 ~g of vinyl acetate, 0.475 kg oi acetaldehyde and 0.45 kg of bis-azo isobutyronitrile is introduced into a pressure autoclave which has a capacity o~ 190 1 and which i~ equipped for stirringO
The air in the autoclave i~ expelled by nitrogen. 32~8 kg of ethylene are then ~orced into the autoclave under pressure from steel cylinders~ The autoclave contents are heated to 650C for 3 hours, to 70C for 3 hours and to 80~ ~or 6 hours.
The pressure ri~es $rom 1~0 bars to 310 bar in the course o~
heating and drops to 40 bars in the course o~ polymerisation, 109.3 kg o~ a 45.4~ polymer ~olution were obtained. The polymer mixture amounts to 83~ based on the qu~ntity of ; monomers put into the process~ The intrinsic viscosit~ `~
:l 15 is 0.38 dl/g and the molecular weight determined by vapour . pressure osmometry is 7300, ; A mixture oi 1000 g of tert.-butanol~ 300 g oi vinyl ~cetate, 5 g oi acetaldehyde9 5 g of bis-~o isobutyronitrile and 700 g of ethylene i~ pumped per hour from below upward~
into two 5 1 autoclave~ joined to iorm a ca~cade, which ~re heated to 65~C ~nd ~O~C~ re~pectively. A~ter pa3 ing through : the two autoclaves, the polymerisation mixture is periodically relie~ed of pres~ure by an excess pressure valve which is ad~u~ted to 20V bars, The average time oi stay o~ the poly-merisation mi~ture in the autoclave i~ about 3 hours~ The e~periment i~ stopped a~ter 60 hour~. The polymerisation ~olution obtai~ed in the period betwean the 50th ~nd 60th hour has a ~olid co~tent oi 29.0% by weight. The volume/time yield is about 400 g/l. The polymer ~reed ~rom volatile constituents cont~ined 30.3% by weight o~ polymerised Yinyl acetate and h~d an intrin~ic visco~ity (~) determined in ~L069~ZS; ~;

p-xylene as the solvent at 25C oî 0.172 dl/g~ The molecular weight determined in toluene by v~pour pressure osmometry is 2550, :

~' ' ' . .

g_ , I

Claims (5)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the production of an ethylene/vinyl acetate co-polymer having a molecular weight of from 500 to 10,000, and intrinsic viscosity numbers of 0.1 to 0.5 dl/g, determined in p-xylene at 25°C, wherein ethylene and vinyl acetate are polymerised radically at a temperature of from 10 to 200°C and a pressure of from 10 - 700 bars in the presence of from 0.2 to 5% by weight of acetaldehyde, based on the quantity of the initial monomers.
2. A process as claimed in claim 1, wherein the molar ratio of ethylene to the vinyl acetate is from 20 : 1 to 1 : 1.
3. A process as claimed in claim 1, wherein the polymerisation occurs in a reaction medium consisting essentially of tertiary butanol.
4. A process for lowering the pour point of a mineral oil fraction having a boiling point of from 120 to 400°C, wherein a copolymer obtained by the process as claimed in claim 1 is added to said mineral oil fraction.
5. A mineral oil fraction having a boiling point of from 120 to 400°C
containing a copolymer obtained by a process as claimed in claim 1.
CA232,723A 1974-08-03 1975-08-01 Process for the preparation of low molecular weight ethylene/vinyl acetate copolymers Expired CA1069925A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19742437490 DE2437490A1 (en) 1974-08-03 1974-08-03 PROCESS FOR THE PRODUCTION OF LOW MOLECULAR AETHYLENE / VINYL ACETATE COPOLYMERISATES

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CA1069925A true CA1069925A (en) 1980-01-15

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JP (1) JPS5138379A (en)
BE (1) BE831959A (en)
CA (1) CA1069925A (en)
DE (1) DE2437490A1 (en)
ES (1) ES439933A1 (en)
FR (1) FR2280656A1 (en)
IT (1) IT1041113B (en)
NL (1) NL7509162A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4675248A (en) * 1983-10-29 1987-06-23 Bayer Aktiengesellschaft Polymer mixtures and co-vulcanizates produced therefrom

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3732721A1 (en) * 1987-09-29 1989-04-06 Ruhrchemie Ag COPOLYMERISATES FROM ETHYLENE AND METHOXY ACETIC ACID VINYL ESTER AND THEIR USE AS ADDITIVES FOR MINERAL OIL DISTILLATES
DE4020640A1 (en) * 1990-06-29 1992-01-02 Hoechst Ag TERPOLYMERISATES OF ETHYLENE, THEIR PRODUCTION AND THEIR USE AS ADDITIVES FOR MINERAL OIL DISTILLATES

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2891936A (en) * 1956-06-12 1959-06-23 Eastman Kodak Co High density polyethylene by high pressure polymerization with small amounts of aldehydes
FR1285925A (en) * 1959-11-02 1962-03-02 Shell Res Ltd Process for the copolymerization of alpha olefins and unsaturated compounds containing a polar substituent

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4675248A (en) * 1983-10-29 1987-06-23 Bayer Aktiengesellschaft Polymer mixtures and co-vulcanizates produced therefrom

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DE2437490A1 (en) 1976-02-12
NL7509162A (en) 1976-02-05
ES439933A1 (en) 1977-03-01
IT1041113B (en) 1980-01-10
BE831959A (en) 1976-02-02
JPS5138379A (en) 1976-03-31
FR2280656A1 (en) 1976-02-27
FR2280656B1 (en) 1979-05-11

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