DE2030573A1 - Process for the production of stabilized copolymers - Google Patents

Description

DR ₁ -INGZVONKREtSLER DR-ING ₁ SCHaNWALD DR.-ING. TH. MEYER DR. FUES DIPL-CHEM. ALEK VON KREISLER DIPL.-CHEM. CAROLA KELLER DR.-ING. KLDPSCH KDLN !, DEICHMANNHAUS

Cologne, June 16, 1970 Kl / Ax / Hz

EGG. du Pont de Nemours and Company, Wilmington, Delaware 19898. (V.St .A.).

Process for the production of _- stabilized co-polymers

The invention relates to the manufacture of normally solid α-monoolefin hydrocarbon copolymers, the Contain norbornylene groups or their substituted derivatives and against gel formation during processing by adding a thiuram disulfide or a bis (di ~ thiocarbamoyl) disulfide are stabilized.

α-monoolefin hydrocarbon copolymers containing norbonylene groups and their substituted derivatives are excellent general-purpose elastomers, but they can be difficult to process and convert into molded parts. A particular problem that occurs during processing results from the fact that the shear stresses occurring during processing are so high that the norbornan ring breaks. If no suitable stabilizer is available, this will result in self-crosslinking triggered and gelation of the polymer caused. Gel formation affects the properties of the polymer and leads to a deterioration in solubility, stickiness and flow properties, and further processing is very difficult and complicated.

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Disadvantageous shear stresses can occur a) during the mixture production, in which these polymers are mixed with fillers, plasticizers, vulcanizing agents and antioxidants, b) during their shaping and / or during pressing, whereby they are forced on roller mixers, calenders, in extrusions and Injection molding machines to flow, and c) while isolating the polymer. In most cases, these operations are not performed sequentially. The mass can thus go through the sequence of heating, cooling and shear or shear stress several times during processing, with each operation giving rise to an opportunity for gel formation. Apart from jobs created by the shear stress problems must the uncured waste that has passed through the complicated processing cycle reused, who ₇ to make the cost to the process. However, waste of norbornene copolymers which has been adversely affected by the shear and shear stresses is no longer suitable for reuse.

Due to the processing difficulties described above, cx-monoolefin-hydrocarbon copolymers, the norbornylene groups or their substituted derivatives contain, technically unacceptable and despite their ease of synthesis and their considerable potential economic value for use in manufacture certain products such as pneumatic tires are unprofitable.

There is thus a need for an agent, a-Monoole ™ fin hydrocarbon copolymers containing norbornylene groups or contain their substituted derivatives, against gel formation during the shear phases of the processing of the mass to stabilize.

The invention accordingly relates to normally solid α-monoolefin-hydrocarbon copolymers ₉ containing 2 to 50 -f'o norbornylene groups and their substituted derivatives

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- 5 - ■ - V

contain and against gel formation during the ßcherphasen the processing of the mass have been stabilized by them evenly with a thiuram disulfide or a Bis (dithiocarbaraoyl) disulfide have been mixed.

For the purposes of the invention, the following are stabilizers suitable:

a) Thiuram disulfides of the general formula

R. S S ^ N-C-S-S-C-N

wherein R ^., R _2, R, and R ^, independently, alkyl radicals Q-C ^ -C ^ for (for convenience and economic reasons are C _x preferred.-C ^ alkyl), Cg-Cj £ -aryl radicals ( and their saturated derivatives), alkaryl radicals (eg tolyl radicals), aralkyl radicals (eg benzyl radicals) or a pair of the radicals R on the same nitrogen atom can be a C -C alkylene radical or 3-oxapentylene radical.

b) bis (dithiocarbamoyl) disulfides of the formula

S S i

Il Il ^

Rc - 0 - C _ S - S - C - 0 -

wherein R ₁ - and R 1 - independently represent C

(For reasons of expediency and economic reasons, C ₂ -Cj ₂ -alkyl radicals are preferred), Cg-C ^ g-aryl radicals (and their saturated derivatives), alkaryl radicals (eg tolyl radicals) or aralkyl radicals (eg benzyl radicals).

Representative and Preferred Thiuram Disulfide Compounds are tetramethylthiuram disulfide, tetraethylthiuram disulf id, - tetrabutylthiuram disulfide, dipentamethylene thiuram disulfide, ifjN'-dimethyl-K ^ li'-diphenylthiuram disulfide,

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N, N'-diethyl-N, N · -diphenylthiuramdi sulfide, N, N · diethyl-Ν, Ν'-dicyclohexylthiuraiidisulfid, Tetrabenzylthiuram disulfide, dicyclohexylthiuram disulfide, tetrabenzylthiuram disulfide, Bis (morpholino) thiuram disulfide and bis (piperidino ) thiuramdi sulfide

As representative and preferred bis (dithiocarbamoyl) disulfide compounds are mentioned:

Bis (dimethylthiocarbamoyl) disulfide Bite (diethylthiocarbamoyl) disulfide Bis (dipropylthiocarbamoyl) disulfide bis (diisopropylthiocarbamoyl) disulfide Bis (dibutylthiocarbamoyl) disulfide bis (dibenzylthiocarbamoyl) disulfide Bis (pentamethylenethiQcarbamoyl) disulfide Bis (diisobutylthiocarbamoyl) disulfide Bis (diisopentylthiocarbamoyl) disulfide Bis (dicyclohexylthiocarbamoyl) disulfide Bis (diphenylthiocarbamoyl) disulfide BisCJ-oxopentamethylene thiocarbamoyl odisulfide Bis (benzylbutylthiocarbamoyl) disulfide bis (butylcyclohexylthiocarbamoyl) disulfide Bis (butylethylthiocarbamoyl) disulfide Bis (butylmethylthiocarbainoyl) disulfide Bis (eyelohexylmethylthiocarbamoyl) disulfide Bis (ethylphenylthiocarbamoyl) disulfide Bis (methylphenylthiocarbamoyl) disulfide.

The compounds identified as bis (dithiocarbamoyl) disulfides are sometimes used as alkylxanthogen disulfide compounds however, the above nomenclature is preferred for the sake of simplicity and consistency and used here.

The stabilizers according to the invention are difunctional, i.e. 1 mole of stabilizer should be per mole of that in the copolymer existing norbornylene component are provided.

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However, an improvement is also achieved if the dem Amount of stabilizer admixed to polymers in the range from about 8 to 100 mol%, preferably 8 to 12 mol% of the actual concentration of the norbornylene or substituted derivative present in the polymer.

The invention is based on normally fixed linear and branched copolymers applicable in which a comonomer is a norbornene which is polymerized into the main chain of the polymer in the form of a norbornylene group (as indicated by the wavy line):

The norbornene has the general formula

where R _{1 is} -, a hydrogen atom, an alkyl radical, aryl radical, alkenyl radical or alkylidene radical, Rg is a hydrogen atom or alkyl radical or R 1 and Rg can be linked to form an alkylene radical. Representative examples include: 2-norbornene, 5- ^fii ethyl-2-norbornene, 5-phenyl-norbornene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, dicyclopentadiene and 5- (2'- Butenyl) -2-norbornene.

The concentration of norbornylene and its derivatives can be between 2 and 50% by weight. When the Norbornylenderivat unsaturated radicals such as alkenyl, alkylidene or alkenylene containing 2 to 15 wt -.%, Preferably because

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the presence of a large amount of unsaturated groups is usually unnecessary for good vulcanization. . In cases where the ITorbornylenderivat is saturated, a concentration of 5 to 40 percent is -% preferred for practical and economic reasons. If the amount of norbornylene groups is higher than 40% by weight, the behavior of the product obtained is more like that of a plastic than an elastomer.

Other monomers that can be used in the manufacture of the copolymers suitable according to the invention are a-I.Ionoolefir.e the formula

Rq - CH = GH ₂

in which Rq is a hydrogen atom or a preferably straight-chain one C, -C,., - alkyl radical. Representative ot monoolefins are ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-octadecene, 5-ethyl-i-decene and 5-methyl-1-hexene. Further monomers which are suitable for the purposes of the invention are the non-conjugated dienes, which can be open-chain or cyclic compounds and contain only one polymerizable double bond in the sense that only one bond of the diene is essential Reacts to a degree in the formation of the main polymer chain. Terminal double bonds and the endocyclic double bond in the 2-position in unsaturated derivatives of 2-norbornene are typical of such active bonds. The open chain dienes have the general formula

? 11

CH ₂ »CH - R ₁₅ -C = C-

in which R., is a C.-C.ß-alkylene radical and R ₁₀ * ^R ii v * ¹ ^ ^R ip are independently hydrogen or alkyl radicals with the proviso that the radicals R (Ri ₀ ' ^ XV ^R 12 ¹ ^ ^R 13 ^ ^{are chosen} so that the diene contains about 6 to 22 carbon atoms. The preferred diene is 1,4-hexadiene. Representative dienes are 1,4-hexadiene, 1,9-octadecadiene, 6-methyl -l _i 5-heptadiene, 7-methyl-1,6-octadiene, ll-ethyl-l, ll-trideeadiene, ^ -ethyl-l ^ -undeca-

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diene, 7-ethyl-1,7-nonadiene, 8-propyl-1,8-undeeadiene, 8-ethyl-1,8-decadiene, IO-ethyl-1,10-dodecadiene, 12-ethyl-1,12- tetradecadiene, 13-n-butyl-1, 12-heptadecadiene and 15-) ethyl-1,15-heptadecadiene. Open-chain dienes with two terminal non-conjugated CC double bonds, where L ₂ , E ^ r and R ^ c are hydrogen atoms, for example 1,5-hexadiene or 1,4-pentadiene, can be used, provided that care is taken is that gel formation is avoided during the copolymerization. Examples of suitable cyclic non-conjugated dienes are dicyclopentadiene, 5-alkenyl-substituted-2-norbornenes, e.g. ^ -butenyl-S-norbornene, 5-alkylidene-2-norbornene (including 5-ethylidene-2-norbornene and 5-foethylene -2-norbornene), 2-alkyl-2,5-norbornadienes (e.g. 2-ethyl-2,5-norbornadiene) and 1,5-cyclooctadiene.

The above monomers can be combined to produce a wide variety of copolymers. Representative copolymers include: ethylene / norbornene, ethylene / 5-ethyl-2-norbornene, ethylene / 5-butyl-2-norbornene / 5-ethylidene-2-norbornene, ethylene / propylene / dicyclopentadiene, ethylene / Propylene / 5-kethylene norbornene, ethylene / propylene / 5-ethylidene-2-noΓboΓnen ₁ ethylene / liorbornene / 1, A - hexadiene, ethylene / propylene / norbornene / 1, ^ - hexadiene, ethylene / propylene / 5-methylene norbornene / Dicyclopentadiene, ethylene / propylene / 5- (2'-3uteriyl) -2-norbornene, ethylene / propylene / 5-ethylidene-2-norbornene / 1,4-hexadiene, ethylene / 5-ethylidene norbornene, ethylene / 5-hexylnorbornene and ethylene / ^ 5- ethylnorbornene / 1, ⁱ l-hexadiene.

Further valuable copolymers can be obtained from the above described monomers are produced. Process for their manufacture are described in the USA patents 2 799 668, 2 883 372 and 2 934-527 and in British U.S. Patent 1,014,311.

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The copolymers according to the invention can by treating the monomers with customary coordination catalysts, which are preferably soluble in inert organic solvents such as tetrachlorethylene, hexane, benzene and cyclohexane are to be produced.

The preferred catalysts consist of the product of the reaction of 1) a vanadium compound such as VOCl ,, VCl ^, vanadium tris-acetylacetonate), vanadium oxybis (acetylacetopnate), trialkyl orthovanadate (eg triethyl orthovanadate) and 2) an organometallic reducing agent, in particular an organoaluminum chloride compound to be favoured. Instead of these vanadium compounds, TiCl ₂ ^ can be used. One of these catalyst components should contain a halogen, preferably chlorine, if the halogen is not supplied through the reaction medium.

Those to be stabilized by the additives according to the invention Copolymers are in solution or as a suspension in the presence of a polymerization catalyst usual process. The stabilizers according to the invention are expediently added to the polymer solution, before the isolation of the polymer takes place. The copolymer can be extracted from the solution by precipitation with ' a non-solvent or by removing the solvent can be isolated by steam distillation or by other customary methods.

The addition of the stabilizers to the polymer is preferably carried out before isolation, but, as illustrated in the examples, can also be achieved successfully by kneading on a roller mixer or in mixers, the polymer and the apparatus both being heated to a temperature in the range from about 80 to 100 ⁰ C are heated. This method of adding the stabilizer can be carried out successfully on a small scale, but is more difficult to achieve on an industrial scale. 0 0 9 8 8 2/2120

The production of mixtures based on copolymers Can be on a rubber V / cylinder mixer, in an internal mixer (e.g. a Banbury mixer or a Struthers-Wells mixer) or with other conventional mixers. The usual mixture ingredients such as fillers, e.g. Soot, clay, silicon dioxide, vulcanizing agents, antioxidants, oils, pigments, etc., can be used at this point can be added. The vulcanization is then according to the usual procedures and under the usual conditions carried out.

The mixing temperature should be between 15 and 95 ° C.

The lower limit of 15 ° C represents the lowest possible ■ temperature for effective kneading on the roller mixer.

and above 95 ° C the shear stress is so low, ' that they are the bicyclic rings in the norbornylene groups 'cannot break in the polymer.

In the following examples, all quantitative data relate to and proportions by weight, unless otherwise specified.

Test methods

A. The plasticities can easily be determined by Wallace plasticity measurements determine. These measurements are made with a Wallace plastimeter (manufacturer H.W Wallace & Co., Limited, London). The plasticity is a measure of the amount of flow or deformation of the unvulcanized elastomeric material under load. The polymer to be tested is processed into plates and cut into granules with a thickness in the range from 3.2 "'to 3.3 mm. First, the test grain is 10 seconds a load of 10 kg for 15 seconds

at 100 ⁰ C subjected. The final thickness of the test specimen in units of 0.01 mm is the plasticity value »

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B. The content of insoluble polymer is determined as follows: Finely cut polymer samples are extracted for 5 hours with boiling η-hexane (if the polymer is not crystalline) or with boiling n-heptane (if the polymer is partially crystalline) «, The clear liquid is decanted into a weighing pan, taking care that the insoluble polymer remains for weighing. The residue is subjected to a further four extractions. The proportion of insoluble polymer is calculated as follows: (weight of the insoluble polymer / weight of the sample) 100. In general, a polymer sample of 5 g is cut into cubes with an edge length of about 3 ₉ 2 mm and extracted with 200 ml of solvent «

example 1

A 20 g sample of a normally solid, essentially amorphous copolymer of ethylene _$ norbornene-2 and 1,4-hexadiene (weight ratio 5?; 41: 2, Wallace plasticity 81) is heated to about 80 ° C. and then to a Given rubber roller mixer, which is also heated ^{to 80 0 C.} While the copolymer is circulating as a closed skin on the roller mixer, 0.4 g of bis (diethylthiocarbamoyl) disulfide is added. B copolymers are kneaded for 10 minutes. A smooth, transparent copolymer forms on the front roller and shows a good mixing bead. The Wallace plasticity after kneading is 87.

For comparison purposes, a second 20 g sample of the same copolymer is treated as described above with the difference that no bis (diethylthiocarbamoyl) disulfide is added. This matching "robe" initially forms a closed area _9, but the copolymer begins to crumble during the first few minutes of kneading and to fall off the roller mixer in pieces. The Wallaee plasticity of the crumbled material is too high to achieve the maximum _{with the Pritfapparat 3}

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Value of 100 has to be measured.

Example 2

A 20 g sample of a normally solid, essentially amorphous copolymers of ethylene and 5- * iethylnorbornen-2 (Weight ratio 62:38, content of hexane-insoluble polymer about 0.1 wt. Yo) »This is a Wallace plasticity of 16 is heated to 95 ° C and placed on a rubber roller mixer given, which also heated to 95 ° C has been. 2 g of tetramethylthiuram disulfide are added to the copolymer added while it circulates as a closed skin on the roller mixer. The copolymer will last 15 minutes kneaded at 95 ° C and has a Wallace plasticity of 13 · The same sample is then put on a roller mixer rolled out to a fur at room temperature and kneaded for 15 minutes. The copolymer sample now has a Wallace plasticity of 15% and only about 3% by weight of the polymer is in hexane insoluble.

lim to show that another type of disulfide is gel formation of the copolymer is not prevented, the experiment described above is repeated in the same way with the Difference that dipentamethylene thiuram hexasulfide in place of tetramethylthiuram disulfide is used. Wallace plasticity of the obtained copolyraeren rises sharply to 4-7, a sign that the copolymer during cooling and Kneading is not protected. Furthermore, the copolymer is insoluble in hot hexane.

Example 3

A normally solid, substantially amorphous copolymer of ethylene and 5-L-ethylnorbornene-2 (weight ratio 62:38, content of hexane-insoluble polymer about 1%) is produced by solution polymerization. 8.75 parts of bis (diethylthiocarbamoyl) disulfide are formed during manufacture added per 100 parts of the copolymer. A 20 g sample of this copolymer, which has a Wallace plasticity of 11 has, is heated to 95 ° C and on a

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Roller mixer, which has also been heated to 95 ° C, rolled out into fur. After the roller mixer has run for about 15 minutes, it is cooled to room temperature. The copolymer is then kneaded at room temperature for 15 minutes. The kneaded copolymer has a Wallace plasticity of 5 and contains about 0.2% polymer, which is insoluble in hexane.

For comparison purposes, a copolymer is prepared in the manner described above, except that no bis (diethylthiocarbamoyl) disulfide is used is added. After the copolymer was 15 minutes at 95 ° C on the roller mixer has been kneaded, it has a Wallace plasticity of 11. After kneading for 15 minutes at room temperature the same sample has a Wallace plasticity of 15 and contains 25% by weight of material which is insoluble in hexane

Example 4

A 20 g sample of a normally solid, substantially amorphous copolymer of 60% by weight ethylene, 29% by weight propylene, 8% by weight norbornene, and 3% by weight 1,4-hexadiene, which is a Wallace plasticity of 40 has, is heated to 95 ⁰ C and rolled to a likewise heated to 95 ⁰ C-roll mixer to coat. 0.4 g of bis (diethylthiocarbainoyl) disulfide is added to the copolymer, followed by kneading for a further 15 minutes. The copolymer obtained still has a Wallace plasticity of 40. The Y / cylinder mixer is then cooled and the copolymer is processed for 15 minutes at room temperature. The copolymer obtained is translucent throughout the treatment, has a final Wallace plasticity of 32 and contains 0.1% by weight of copolymer which is insoluble in hexane.

For comparison purposes, a second sample of the copolymer is prepared in the manner described above, but with * no bis (diethylthiocarbamoyl) disulfide is added. After a processing time of 15 minutes at 95 ° C the copolymer still has a Wallace plasticity of 40.

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However, by further kneading for 5 minutes i "at room temperature the coat of the copolymer is opaque and the surface becomes grainy The Wallace plasticity is increased to 73, and the sample containing 38 wt -..% Hexanunlösliches copolymer.

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Claims (1)

Claim Process for the production of normally solid coals water copolymers, e.g. of ethylene-butylnorbornene-ethylidene norbornene copolymers, which is about 2 to 50% by weight preferably 2 to 15 wt .- / α norbornylene groups or substituted Derivatives of norbdrnylene groups of the general formula 7 ^H 8 contain, in which R ~ a hydrogen atom, an alkyl radical, Aryl radical, alkenyl radical or alkylidene radical, Rg is a hydrogen atom or is an alkyl radical or R ^ and Rg form one Alkenylene radical are connected, characterized in that the copolymers during the shear phases of processing the mass can be stabilized by adding one of the following stabilizers: a) Thiuram disulfides, e.g. tetramethylthiuram disulfide, the general formula R ,. S S R 11 η in which R ^ , R ₂ , R * and R ^ independently represent C ^ -O ^ g -alkyl radicals, Gg-C ^ g-raryl radicals and their saturated derivatives, alkaryl radicals or aralkyl radicals, or a pair of the radicals R on the same nitrogen atom Can be CL-Ce-alkylene radical or 3-oxapentalen radical, or b) bis (dithiocarbamoyl) disulfide, e.g. bis (diethylthiocarbamoyl) disulfide, the, general formula S S. R_-O-C-S-S-C-O- : 009882/2120 where Rc and Rg independently for O ^ - Cβ-CLg aryl radicals and their saturated derivatives, alkaryl radicals or aralkyl radicals, wherein the stabilizer in an amount of about 8 to 100 Mol-? " is present per mole of norbornylene component in the copolymer. . 009882/2120