Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-01-12
2001-10-30
Teskin, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S139000, C526S140000, C526S141000, C526S142000, C526S169100, C526S335000, C526S340300, C526S340400
Reexamination Certificate
active
06310151
ABSTRACT:
This invention relates to a process for the polymerisation of conjugated diolefins with catalysts based on cobalt compounds in the presence of aromatic vinyl compounds.
It has long been known to polymerise conjugated dienes in the presence of a solvent and such polymerisation has been described, for example, by W. Hoffmann,
Rubber Technology Handbook,
Hanser Publishers (Carl Hanser Verlag), Munich, Vienna, New York, 1989. Polybutadiene, for example, is accordingly now predominantly produced by solution polymerisation using coordination catalysts of the Zielger/Natta type, for example based on titanium, cobalt, nickel and neodymium compounds, or in the presence of alkyllithium compounds. The solvent used in each case is highly dependent upon the type of catalyst used. Benzene or toluene as well as aliphatic or cycloaliphatic hydrocarbons are preferably used.
A disadvantage of currently performed polymerisation processes for the production of polydiolefins, such as for example BR, IR, SBR, is the elaborate working up of the polymer solution to isolate the polymers, for example by steam stripping or direct evaporation. A further disadvantage, especially if the polymerised diolefins are to be further processed as impact modifiers for plastics applications, is that the resultant polymeric diolefins must initially be redissolved in a new solvent, for example styrene, so that they may be further processed to yield, for example, acrylonitrile/butadiene/styrene copolymer (ABS) or high impact polystyrene (HIPS).
U.S. Pat. No. 3 299 178 claims a catalyst system based on TiCl
4
/iodine/Al(iso-Bu)
3
for the polymerisation of butadiene in styrene to form homogeneous polybutadiene. Harwart et al.,
Plaste und Kautschuk,
24/8 (1977) 540, describe the copolymerisation of butadiene and styrene using the same catalyst system and the suitability of the catalyst for the production of polystyrene.
It is known from U.S. Pat. No. 4,311,819 to use anionic initiators for the polymerisation of butadiene in styrene. The disadvantage of the anionic initiators is that they result in the formation of butadiene/styrene copolymers (SBR) which, in relation to the butadiene units, permit only slight control of microstructure. It is only possible to increase the proportion of 1,2 or 1,4-trans units by adding modifiers, which results in an increase in the glass transition temperature of the polymer. Using anionic initiators, it is not possible to produce an SBR having an elevated cis content. This fact is primarily disadvantageous because SBR is formed in this process in which, in comparison with homopolymeric polybutadiene (BR), a rising styrene content results in a further increase in the glass transition temperature. However, if the rubber is to be used for impact modification of for example HIPS or ABS, an elevated glass transition temperature of the rubber has a disadvantageous effect on the low temperature properties of the material.
Kobayashi et al,
J. Polym. Sci., Part A, Polym. Chem.,
33 (1995) 2175 and 36 (1998) 241 have described a catalyst system consisting of halogenated rare earth acetates, such as Nd(OCOCCl
3
)
3
or Gd(OCOCF
3
)
3
, with tri(isobutyl)aluminium and diethyl-aluminium chloride, which allows the copolymerisation of butadiene and styrene in the inert solvent hexane. Apart from the presence of inert solvents, the disadvantage of these catalysts is that, at a styrene incorporation of as little as approx. 5 mol. %, the catalyst activity falls to below 10 g of polymer/mmol. of catalyst/h and that the 1,4-cis content of the polymer falls distinctly as the styrene content rises.
U.S. Pat. No. 5,096,970 and EP 304088 describe a process for the production of polybutadiene in styrene using catalysts based on neodymium phosphonates, organic aluminium compounds, such as di(isobutyl)aluminium hydride (DIBAH), and a Lewis acid containing halogen, such as ethylaluminium sesquichloride, in which butadiene is reacted in styrene without further addition of inert solvents to yield a 1,4-cis-polybutadiene.
A disadvantage of this catalyst is that the resultant polymers have a very low content of 1,2 units of below 1%. This is disadvantageous because a higher 1,2 content in the polymer has a favourable effect on the grafting behaviour between rubber and the polymer matrix, for example homo- or copolymers of vinyl aromatic compounds.
The rubber solutions in styrene described in the stated patent publications have been used for the production of HIPS by combining the rubber solutions in styrene with free-radical initiators once the unreacted monomer had been removed.
The object of the present invention was accordingly to provide a process for the polymerisation of conjugated diolefins in vinyl aromatic solvents, by means of which it is possible to obtain polydienes having a content of 1,2 units of above 1%, wherein the content of 1,2 units may be varied in a simple manner and an elevated conversion of the conjugated diolefins used of above 50% may be obtained. Moreover, virtually none of the vinyl aromatic solvent used should be reacted, i.e. conversion should be below 1%.
The present invention accordingly provides a process for the polymerisation of conjugated diolefins, which process is characterised in that polymerisation of the diolefins used is performed in the presence of catalysts consisting of
a) cobalt compounds,
b) organoaluminium compounds and
c) modifiers
as well as in the presence of vinyl aromatic compounds at temperatures of −30° C. to +80° C., wherein the molar ratio of components a):b):c) is in the range from 1:10-1000:0.1-100, the quantity of component (a) of the catalyst used is 1 &mgr;mol. to 10 mmol., relative to 100 g of the monomers used, and the quantity of aromatic vinyl compounds is 10 g to 2000 g, relative to 100 g of the monomers used.
Components a):b):c) are preferably used in the process according to the invention in the range from 1:10-500:0.5-50.
Conjugated diolefins which may be used in the process according to the invention are, for example 1,3-butadiene, 1,3-isoprene, 2,3-dimethylbutadiene, 2,4-hexadiene, 1,3-pentadiene and/or 2-methyl-1,3-pentadiene.
Cobalt compounds (component (a)) which may in particular be considered are those which are soluble in inert organic solvents and are selected from the groups consisting of
I complexes of &bgr;-diketones with cobalt,
II &bgr;-keto acid complexes of cobalt,
III cobalt salts of organic acids having 6 to 15 carbon atoms,
IV complexes of halogenated cobalt compounds of the formula CoX
a
D
b
, wherein X denotes a halogen atom, a means the numbers 2 or 3, D is an organic compound selected from the group consisting of tertiary amines, alcohols, tertiary phosphines, ketones and N,N-dialkylamides and b means a number from 0 to 6, and
V organometal complexes of cobalt with &pgr;-bonded anions.
Cobalt compounds (component (a)) soluble in inert organic solvents which may, for example be used are:
(I) &bgr;-diketone cobalt complexes with &bgr;-diketonates of the formula R
1
—CO—CR
2
—CO—R
3
, wherein R
1
to R
3
may be identical or different and denote hydrogen or an alkyl group having 1 to 10, preferably 1 to 4 C atoms, for example Co(Me—CO—CH—CO—Me)
2
and Co(Me—CO—CH—CO—Me)
3
;
(II) &bgr;-keto acid ester complexes of cobalt with keto acid esters of the formula R
1
—CO—CR
2
—CO—O—R
3
, wherein R
1
to R
3
may be identical or different and denote hydrogen or an alkyl group having 1 to 10, preferably 1 to 4 C atoms, for example Co(Me—CO—CH—CO—O—Me)
2
, Co(Me—CO—CH—CO—O—Et)
2
, Co(Me—CO—CH—CO—O—Me)
3
and Co(Me—CO—CH
2
—CO—O—Et)
3
;
(III) cobalt salts of organic acids having 6 to 15, preferably 6 to 10 carbon atoms, for example Co(octanoate)
2
, Co(versatate)
2
;
(IV) complexes of halogenated cobalt compounds of the above formula CoX
a
D
b
, for example CoCl
2
(pyridine)
2
, CoBr
2
(pyridine)
2
, CoCl
2
(PPh
3
)
2
, CoBr
2
(PPh
3
)
2
, COCl
2
(vinylimidazole)
4
, CoCl
2
(EtOH);
(V) organometal complexes of cobalt with &pgr;-bonded anions, for example tris-(&pgr;-allyl)cobalt, bis-(&pgr;-allyl)cobalt chloride, bis-(&pgr;-a
Michels Gisbert
Obrecht Werner
Steinhauser Norbert
Windisch Heike
Bayer Aktiengesellschaft
Franks James R.
Gil Joseph C.
Teskin Fred
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