DE2149121A1 - Process for crosslinking ethylene-vinyl ester copolymers - Google Patents

Description

VEB Leuna-Werke "Walter Ulbricht" Leuna, 1.9 · 1970 Patent department DC.Schl / Ry

"P" 7038

Process for crosslinking ethylene-vinyl ester copolymers

The invention relates to a method for crosslinking Polyolefins * their copolymers and graft polymers

Ea is known in the crosslinking of polyolefins or their copolymers peroxides to be used · The peroxides for the initiation of the reaction are alkyl- or aryl-substituted Diacyl peroxides, bisperoxides of alkyl-substituted ones Hexynes alkyl- or aryl-substituted bisperoxydiisopropylbenzenes, alkyl- or aryl-substituted bisperoxypolymethylenes and alkyl-substituted polyperoxides described ·>

It is also known, the peroxidic crosslinking of copolymers of ethylene and other low molecular weight to make olefinic compounds with, ■ vinyl esters

It is also known, polyolefins, vinyl ester-containing polyolefins and to crosslink grafted vinyl ester-containing polyolefins using electron beams and UV radiation

The peroxides mentioned and 1,1-di-tert-butyl peroxide are also known as initiators for high-pressure polymerizations to be used (Viederl P. 295 066)

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Finally, it is known that crosslinking is triggered by alkoxy salts of mono- and polyvalent metals (DWP 70 335) 70 386, 7Θ 387, 70 388)

However, the peroxide most frequently used for these purposes, dicumyl peroxide, has the disadvantage that the finished products Products have an unpleasant odor. Other peroxides, such as mesityl oxide peroxide, tend to discolour of the polymers or, as in the case of di-tert-butyl peroxide poorly reproducible results due to high volatility.

The purpose of the invention is, if appropriate, polyolefins, their copolymers, graft polymers or mixtures with fillers or foams as well as accelerators, so too crosslink so that the crosslinked polymer has no unpleasant odor.

The invention is based on the object as a crosslinking agent to use a peroxide that is as constant as possible. Has activity.

This object is achieved in that the polymer at temperatures from 20 to 180 ⁰ C according to the invention as a crosslinking agent from 0.01 to 10 wt * - £, preferably 0.1 to 3 $ Gew.v-, based on the amount of polymer, 1.1 -Ditertiary butylperoxycyclohexane TOgeaectat is made.

The crosslinking is carried out in a manner known per se on extruders, kneaders or presses at the temperatures mentioned

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LP 7038 - 3 -

under Hormaldruok »possibly in the presence τοη Accelerators such as triallyl cyanurate, triallyl phosphate or other allyl esters and sulfur or sulfur-releasing compounds.

Sin is advantage of the invention & oen traversed that the crosslinking at relatiT low temperatures can be performed, which is for the granulation τοη vernetsten Ithylon-vinyl acetate copolymers having vinyl acetate content of importance hohsa · ^N ·

Another advantage is that it uses Peroxide is present as a liquid at normal temperature and is evenly distributed over the polymer in high-speed mixers can be·

Of particular distribution is "dad that according to the invention Process verne do finished products do not have an unpleasant odor »whatever for different purposes this «white · crosslinked polymers is necessary ·

Another advantage is the relatively high flash point of the i.i-Ditert.-butylperoxycyclohexene, which works safely guaranteed.

The products linked to the invention represent colorless » dimensionally stable elastic hating dar · You can after the usual plastic processing methods are processed · The Application of the products focuses on cable sheathing

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lung compounds for other thermoplastics and floor coverings.

The invention is illustrated by means of a few examples Example 1: .

3-leg ethylene / vinyl acetate copolymer with 20 wt .- # vinyl acetate and with a melt index i ₂ -16 * 147 g / 10 min are mixed with 6 g 1,1-tert-butylperoxycyclohexane in a high-speed mixer within 5 min 150 ⁰ C crosslinked in the crosslinking zone · The resulting granulate has a melt index ig <| g "1» 3 g / 10min ·

Example 21

isat

3 kg of ethylene vinyl acetate copolymer with 35 wt. - £ vinyl acetate and a melt index ig -jg «156 g / 10min are mixed in a high-speed mixer with 7 g of 1, i-di-tert-butylperoxycyolohexane within 5 mh and at the same time 120 g of a color center, consisting of polyethylene with a colored pigment, added · on the twin screw extruder the product at 150 ⁰ C in the Vernetzerzone is crosslinked · the colored granules have einen'Schmelzindex of ± 2 * Ot -JG 4 g / 10 min ·

Example 3t

On a mixing roller 15 g of 1,1-DiterW-butylperoxycyolohexan in 3 1 Xthylen-vinyl acetate Copolyiaerisat Kit "at a temperature of 80 to 100 ⁰ C inen vinyl acetate

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IP 7038 - 5 -

content τοπ 45 eew .- »Jt and a melt index I ₂ -jg · 240 g / 10 min incorporated · This mixture is crosslinked for 20 min at 140 * G in a press. t1 g / 1 ©

Example 4t

On a tiner mixing roller at a temperature of 80 to 100 ⁰ O 6.5 g of II-Ditert.-butylperoxycyclohejcan and 60 g of asodicarbonamide in 3 kg of ithylen ^ vinyl acetate copolymer with a vinyl acetate content of 35 öew.-jt and a melt index I ₂ T5 -156 g / 10 min · incorporated laughing reaching a uniform melt is foamed the product on aluminum plates at 180 ⁰ O while rernetzt · the foam has a density of from 0 _t 25 g / cm ^3.

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Claims (2)

I.P 7038 - 6 - patent claims 1. Process for crosslinking polyolefins and their Copolymers and graft polymers or such mixtures with the addition of a crosslinking agent, if appropriate together with fillers or foams as well as accelerator g like, characterized at temperatures from 20 to 180 ⁰ C _1, characterized in 'DAFL as a crosslinking agent, 0.01 to 10 wt .-%, preferably 0.1 to 3 parts by weight-56 1,1-di-tert used -butylperoxycyclohexan will, 2. The method according to claim 1, characterized in that an ethylene-vinyl acetate copolymer is crosslinked 2098 16/1363