DD237070A3 - PROCESS FOR PREPARING AGING-RESISTANT NORBORNE AETHYLENE COPOLYMER - Google Patents

Abstract

The invention relates to a process for the preparation of aging-resistant norbornene-ethylene copolymer according to DD-PS 109 224 with a transparency greater than 90%, high mechanical strength and very good electrical characteristics. For the preparation of these copolymers, norbornene is added to the titanium mixed catalyst according to DD-PS 109 224 in the catalyst formation, and only the catalyst filtrate is used for the polymerization. In addition to the achievement of transparency by so produced catalysts whose activity is much higher than without norbornene treatment. Due to their transparency, good mechanical strength and very good dielectric properties, the norbornene-ethylene copolymers produced have an extended field of application, in particular in electrical engineering / electronics and precision mechanics / optics.

Description

Field of application of the invention

The invention relates to a method for producing age-resistant norbornene-ethylene copolymers according to DD

Compared to the o.g. Patent prepared norbornene-ethylene copolymers, the copolymers prepared by this process have a higher purity and transparency, so that an expanded field of application in the plastanwendenden industries, especially in electrical engineering / electronics and in precision engineering / optics, opens up

Characteristic of the known technical solutions

According to DD-PS 109 224 is a method for producing non-aging norbornene-ethylene copolymers using Ziegler-Natta mixed catalysts known, wherein the copolymerization by means of catalyst systems au titanium salts of the general formula TiX ₄ _ _n (OR) n and TiX ₃ in which X represents a halogen, preferably Cl, Br, I or mixtures of these halogens, and R represents an alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl grouping group, and η has the values 0 to 4, as well as mean organoaluminium of general formula AIR ₃ _ _m X _m, in which R is a hydride, alkyl, cycloalkyl, or arylalkyl group and X is a halogen, preferably Cl, Br, I or a ligand of the type (oR), wherein R is an alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl group and m is 1 or 2 is carried out. When using these mixed catalysts, the norbornene-ethylene copolymer formed always contains a proportion of polyethylene.

This proportion increases with decreasing polymerization temperature and leads to clouding of the copolymer and to the reduction of mechanical strength due to poor compatibility of polyethylene and norbornene-ethylene copolymers. However, low polymerization temperatures, which promote enhanced polyethylene formation, are advantageous for the preparation of high molecular weight norbornene-ethylene copolymers and thus for increasing their mechanical strength. Furthermore, low temperatures favor the formation of finely divided suspensions from the norbornene-ethylene copolymers formed during the synthesis and the liquid phase. This provides good conditions for large-scale production of these copolymers according to a relatively simple technology. Furthermore, the titanium mixed catalysts can gerräß DD-PS 109224 from the copolymers formed by a simple wash, z. B. with alcohols or gasoline-Alkoliol mixtures, not so far wash that caused by them turbidity can be avoided. Even polythene-free norbornene-ethylene copolymers can not be processed into transparent moldings after such washing. Catalyst particles of mixed titanium catalysts also act in brittle-hard polymers, including most of the vinyl-analogous norbornene-ethylene copolymers, cracking in impact, impact, flexural, and tensile, and generally result in deterioration of dielectric properties and electrical breakdown strength.

For an efficient Katalysatorauswäsche from the copolymers therefore a complex, high-cost technology is required.

Object of the invention

The aim of the invention is the preparation of vinyl-analogous norbomene-ethylene copolymers having a transparency greater than 90%, high mechanical strengths and very good electrical characteristics.

Explanation of the essence of the invention

The object of the invention is to develop a process for the preparation of transparent, aging-resistant norbornene-ethylene copolymers. In this case, the formation of polyethylene as a byproduct of the copolymerization should be avoided and the residual catalyst content should be so low by simple copolymer washing that the copolymers have a transparency of over 90%.

This object is achieved by a process for the preparation of aging-resistant norbornene-ethylene copolymers using Ziegler-Natta mixed catalysts by the copolymerization by means of catalyst systems of titanium salts of the general formula TiX ₄ _ _n (OR) n or TiX ₃ , in X is a halogen, preferably Cl, Br, I or mixtures of these halogens, and R is an alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl grouping, and η is 0 to 4, and organoaluminum compounds of the general formula AIR ₃ _ _m X _m, in which R is a hydride, alkyl, cycloalkyl, or arylalkyl group and X is a halogen, preferably Cl, Br, I or a ligand of the type (oR), where R is an alkyl , Cycloalkyl, aryl, alkylaryl or arylalkyl group and m is 1 or 2, is carried out, according to the invention titanium mixed catalysts are combined with norbornene at a temperature of 195 K to 373 K under atmospheric pressure at closing the catalyst from 273K to 373K for 2 to 300 minutes and the catalyst is used for the copolymerization.

Advantageously, the combination of the catalyst components takes place at temperatures of 243 K to 333 K. The norbornene concentration in the catalyst formation is advantageously 0.25 to 5.00 mol / l. The catalyst aging is advantageously carried out at temperatures of 293 K to 353 K. Advantageously, the aging time in catalyst preparation is 5 to 180 minutes.

  Surprisingly, it has been found that in the norbornene-ethylene copolymerization, polyethylene formation is almost completely absent when the catalyst filtrate of the catalyst prepared from titanium salts, organoaluminum and norbornene is used. This is in contrast to the prior art that catalyst suspensions of titanium salts and organoaluminum compounds - with the exception of Biscyclopentadienyl-titanium complexes and analogous titanium compounds - consist of the active solid and the inactive solution.

Surprisingly, it was further found that the catalysts according to the invention are much more active than treated without norbornene, so that the polymerization proceeds very quickly even at temperatures below 293 K and that a finely divided, well-processed Norbomen-ethylene copolymer is formed.

When using the Kataiysatorfiltrate arise copolymers which have such a low residual catalyst content after technologically simple washing with alcohols or alcohol / gasoline mixtures that test plates made therefrom have a transparency of over 90%.

The norbornene-ethylene copolymers prepared according to the invention have dielectric constants of less than 2.5, dielectric loss factors below 10 ^-3, and electrical breakdown strengths of 1 mm plates of 30 to 45 kV / mm and, for polyolefins, exceptionally high tensile strengths of 60 to 70 N / mm ² .

The separation of the inactive for the norbomene-ethylene copolymerization solids of the catalyst suspension prepared using conventional inert filter systems in the absence of air and moisture. Suitable z. As glass, ceramic or metal filter of various types with and without filter aid, the use of filter aids is advantageous because of the longer usability of such filter combinations.

The activity of the catalyst filtrate is determined by a variety of synthesis parameters. These include the aluminum / titanium ratio, the titanium concentration, the component mixing temperature, the catalyst aging temperature, and the aging time. Preferably, for the preparation of the catalyst, the aluminum / titanium ratio is chosen between 2 and 10, the components are combined at temperatures below 293K and the aging is carried out at temperatures between 293K and 373K.

embodiment example 1

2.5 mmol of titanium tetrachloride as a 1 molar solution in heptane and 5 mmol of diethylaluminum monochloride as a 1 molar solution in heptane are combined at 323 K and stirred at this temperature for 1 hour. After addition of 40 mmol norbornene as 80gew .-% solution in heptane is stirred for a further hour at 323 K.

The catalyst suspension is filtered through a G 4 frit. The filtrate is used for norbornene-ethylene copolymerization.

The copolymerization is carried out under anaerobic conditions at 263 K in heptane at a norbornene concentration of 2 mol / l and an ethylene pressure of 10 ⁵ Pa. With a batch volume of 1 liter, an initial polymerization rate as a measure of the catalyst activity of 1.3 10 " ⁴ mol l" ¹ s " ^{1 is} achieved.

The polymerization is stopped with 5 ml of methanol. Subsequently, the polymer suspension is poured into methanol, filtered off after a residence time of 2 hours and dried at 373 K in vacuo.

Example 2

The catalyst is prepared as described in Example 1. Instead of 5 mmol Diäthylaluminiummonochlorid be

When using this catalyst solution for the copolymerization analogous to Example 1, there is an initial polymerization of 3.8 · 10 " ⁴ ITIoI l ' ¹ s". ¹

Example 3

The catalyst is prepared analogously to Example 1 with 2.5 mmol of titanium tetrachloride, but with 12.5 mol of diethylaluminum monochloride and 20 mmol of norbornene.

The Anfangspolymerisationsgeschwindigkeit when using this catalyst solution for the copolymerization as in Example 1 is 5.1 x 10 ^-4 mol 1 "S ^{1 -1.}

Example 4

For the catalyst preparation, 2.5 mmol of titanium tetrachloride and 7.5 mmol of diethylaluminum monochloride are combined as solutions in heptane at 323 K so that the titanium tetrachloride concentration is 53 mmol / l. After one hour reaction time at 323K with stirring norbornene is added in such amounts that its concentration is 1 mol / l. After another hour of reaction time at 323 K, the catalyst solution is filtered off with suction through a glass frit and used for the copolymerization of norbornene with ethylene.

The copolymerization takes place under the conditions given in Example 1. The initial polymerization rate as a measure of the catalyst activity is 1.76 x 10 -6 moles of 1 " ¹ S ^-1 .

Example 5

The catalyst preparation is carried out in the manner indicated in Example 4, however, such that the titanium tetrachloride concentration is 155 mmol / l.

When using the catalyst solution thus prepared, the copolymerization proceeds at a rate of 4.96.times.10.sup.- ⁴ mol.sup.- ¹ s ^-1 .

Example 6

The catalyst is prepared by adding 1 mmol of titanium tetrachloride and 3 mmol of diethylaluminum monochloride in each case as n-heptane solution at 273 K. After 5 minutes, so much norbornene is added that the norbornene concentration is 1 mol / l. After a reaction time of 30 minutes at 323 K, the catalyst suspension is filtered through a glass frit with silica gel powder and used for the norbornene-ethylene copolymerization analogous to Example 1. When the catalyst solution thus prepared is used, the copolymerization proceeds with an initial polymerization rate of 4.4 × 10 -4 mol of T ¹ S ^-1 .

Example 7

The catalyst solution is prepared analogously to Example 6. The addition of norbornene, however, is such that the norbornene concentration is 4 mol / l.

When using the catalyst solution thus prepared, the initial polymerization rate is reduced compared to Example 6 to 2.7 · 10 " ⁴ mol T ¹ S ' ¹ .

Example 8

For the preparation of the catalyst solution, 2.5 mmol of titanium tetrachloride and 7.5 mmol of diethylaluminum monochloride are combined as a 1 molar hexane solution at 303K and stirred for 1 hour at this temperature. Subsequently, 8 mmol of norbornene are added as a 80% strength by weight solution and stirred at 323 K for 1 hour. The filtered catalyst solution is used for the norbornene-ethylene copolymerization, which is carried out analogously to Example 1, but in hexane. The Anfangspolymerisationsgeschwindigkeit is 4.5 × 10 ^-4 mol Γ ¹ s' ^1.

Example 9

2.5 mmol of TiCl ₄ and 7.5 mmol of diethylaluminum monochloride are combined as a 1 molar hexane solution at 223 K and stirred for 1 hour. Subsequently, 8 mmoles of norbornene are added as a 80% strength by weight solution and stirred at 323 K for an additional hour. After filtration, the catalyst solution for the copolymerization of norbornene with ethylene is used analogously to Example 8.

The catalyst activity is increased in this synthesis so that the initial polymerization is 10.1 10 " ⁴ mol Γ ¹ s" ¹ .

Example 10

8mmol norbornene as 80gew .-% solution in a technical hexane, 1 mmol of titanium tetrachloride and 3 mmol of diethylaluminum monochloride as each Imolare solutions in technical hexane are combined at 273 K and stirred for 5 minutes. It is then heated to 323K and aged at this temperature for 15 minutes with stirring. After filtration through a G4 frit, the catalyst solution for the copolymerization is used analogously to Example 1, being used as a polymerization medium also technical hexane instead of heptane.

In this case, the copolymerization begins at a polymerization rate of 2.4.times.10.sup.- ⁴ mol of T ¹ S " ¹ . After 1 hour, the polymer yield of 90 g is obtained.

Example 11

The catalyst is prepared as in Example 10. The aging time, however, is 30min at 323K.

If the copolymerization is carried out analogously to Example 10 with the catalyst, it begins at a rate of 2.5 · 10 ~ ⁴ mol Γ ¹ s ~ ¹ and reaches a conversion of 108 g after 1 hour.

ieispiei 12

) the catalyst is prepared as in Example 10. The aging lasts 2 hours at 323 K.) ie copolymerization analogously to Example 10 extends in this Katalysatorfiltrat only with a ^ nfangspolymerisationsgeschwindigkeitvon 0.7 x 10 ~ ⁴ mol Γ ¹ s ^"1. The conversion after 1 hour is reduced to 25g.

Seismic Example 13

mmol of titanium tetrachloride and 3 mmol of diethylaluminum monochloride as a 1 molar solution in heptane and 8 mmol of iodobornene as 80 wt% heptane solution are mixed at 273K for 5 minutes, then heated rapidly to 313K and aged at a temperature of 1 hour. The catalyst filtrate is used for the copolymerization analogous to Example 1. The nfangspolymerisationsgeschwindigkeit ^ s is 2.74 x 10 ~ ⁴ mol Γ ^{1 -1.}

Seismic Example 14

The catalyst preparation is carried out analogously to Example 13, but the aging is carried out at 333 K for 20 minutes. Be use of Katalysatorfiltrats runs the copolymerization as in Example 1 with a nfangspolymerisationsgeschwindigkeitvon ^ 1.87 x 10 ~ ⁴ mol Γ ¹ s ^-1.

ieispiei 15

The catalyst preparation is carried out analogously to Example 13. However, the aging only lasts 7 minutes at 353 K. The copolymerization of norbornene with ethylene analogously to Example 1 starts with the use of this catalyst filtrate at a rate of 0.76 × 10 -4 mol ^-1 s ^-1 .

MIe copolymers prepared according to the embodiments have a polyethylene content of less than 1 wt .-%. Sheets of 4mm thickness produced from this had a transparency of over 90%. The dielectric constant> is 2.3. The dielectric loss factor tan delta is 4 χ 10 ~ ^4, and the dielectric strength is 40 bis45kV / mm. The fatigue strengths after 4 hours of polymerization are 60 to 70 N / mm ² .

Claims (5)

-1 - 237 07) Invention claim: 1. A process for the preparation of aging-resistant norbornene-ethylene copolymers using Ziegler-Natta mixed catalysts, wherein the copolymerization by means of catalyst systems of titanium salts of the general form «TiX ₄ _ _n (OR) n or TiX ₃ , in which X a Halogen, preferably Cl, Br, J or mixtures of these halogens, and R represents an alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl grouping, and η takes the values 0 to 4, as well as organoaluminum compounds of the general formula AIR3_ _m X _m , in which R is a hydride, alkyl, cycloalkyl or arylalkyl group and X is a halogen, preferably Cl, Br, J or a ligand of the type (OR), where pure alkyl, cycloalkyl, aryl , Represents alkylaryl or arylalkyl group and m is 1 or 2, is carried out, according to DD-PS 109224, characterized in that the titanium mixed catalysts are combined with norbornene at temperatures of 195 K to 373 K under atmospheric pressure, then end the catalyst aging at 273K to 373K for 2 to 300 minutes is performed un the Katalysatorfiltrat is used for copolymerization. 2. A process for the preparation of aging-resistant norbornene-ethylene copolymer according to item 1, characterized in that the combination of the catalyst components takes place at temperatures of 243 K to 333 K. 3. A process for the preparation of aging-resistant norbornene-ethylene copolymer according to item 1, characterized in that the norbornene concentration in the catalyst formation is 0.25 to 5.00 mol / l. 4. A process for the preparation of aging-resistant norbornene-ethylene copolymer according to item 1, characterized in that the catalyst aging takes place at temperatures of 293 K to 353 K. 5. A process for the preparation of aging-resistant norbornene-ethylene copolymer according to item 1, characterized in that the aging time in the catalyst preparation is 5 to 180 minutes.