DE3202545A1 - ETHYLENE COPOLYMERS, THEIR PRODUCTION AND USE - Google Patents

Description

-A-

SOCIETE CHIMIQUE DES CHARBONNAGES S.A. 92o8o Paris La Defense, France

Ethylene copolymers, their preparation and

use

The invention relates to ethylene copolymers with units derived from maleic anhydride, their Manufacture and their use for the production of films.

FR-PS 1 323 379 describes terpolymers of ethylene, an alkyl acrylate and maleic anhydride which have low crystallinity and for modifying petroleum waxes for coating of paper with a proportion of 5 to 10% by weight in the waxes are suitable.

721-cas 5048-SF-Bk

The invention is based on the object of improved ethylene copolymers which contain ethylene as the main monomer as well at least two comonomers, namely an acrylic acid ester and / or methacrylic acid ester and maleic anhydride, and specify a process for their manufacture.

The problem is solved according to the claims.

The ethylene copolymers according to the invention contain

88 to 98.7 mol% of units derived from ethylene, 1 to 10 mol% of at least one below C ₁ - bis

Cg-alkyl acrylates and C ..- to C _g alkyl methacrylates selected esters derived units

0.3 to 3 mol% derived from maleic anhydride

units

and are characterized by a flow index according to ASTM D 1238-73 of 1 to 500 dg / min, a uniformity M / M> 6 and a softening point according to Vicat between 30 ^° C. with high comonomer contents and 85 ^° C. with low comonomer contents.

The ethylene copolymers according to the invention are in principle terpolymers or quaterpolymers however, optionally also a fourth or fifth, copolymerizable with the three or four main monomers contain further comonomer; in this case they represent quaternary or quinternary copolymers.

If the inventive ethylene copolymers contain a further comonomer, this can be selected from the C ₀ - to C ₀ -OC olefins, monoalkyl maleates and di-

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alkyl maleates each with C- to Cg-alkyl groups, vinyl acetate and carbon monoxide be selected and present in an amount of up to 5 mol%, in which case the proportion of ethylene in the ternary copolymer is decreased in accordance with the above range.

The process according to the invention for producing the ethylene copolymers is based on the copolymerization of a mixture of 94 to 99% by weight of ethylene, 0.7 to 5% by weight of at least one acrylic acid and / or methacrylic acid ester and 0.2 to 0.9 % By weight maleic anhydride and optionally a _{further comonomer selected from the C 1 to C fi} -κ olefins, monoalkyl maleates and dialkyl maleates each having C 1 to C _fi alkyl groups, vinyl acetate and carbon monoxide in the presence of at least one initiator of the radical polymerization 170 to 280 ⁰ C in a kept under a pressure of 1000 to 3000 bar reactor, the expansion of the reactor mixture, the separation of the monomer mixture from the ethylene copolymer formed in the reactor and the recycling of the separated monomer mixture into the reactor and is characterized in that the Recirculated monomer mixture contains 99 to 99.8% ethylene and 0.2 to 1% acrylic acid ester and / or methacrylic acid ester.

In the method according to the invention, a separate Feeding in of fresh ethylene on the one hand and the comonomers and the recycled ethylene on the other hand are provided. The comonomers are preferably introduced into the reactor by injection a solution of maleic anhydride in the acrylic acid ester and / or methacrylic acid ester under pressure, mixing

this solution with the ethylene stream and homogenization of this mixture before entering the reactor.

Mixing and homogenization can, for example, take place simultaneously in a venturi-type device take place, but the method according to the invention is not limited to this.

It is also possible to use the recycled ethylene and the recycled acrylic or methacrylic acid ester to separate, however, this procedure does not bring any advantages that result in increased production costs outweigh.

In the context of the invention, for example, 2-ethylhexyl peroxydicarbonate, Di-t-butyl peroxide, t-butyl perbenzoate and, for example, t-butyl 2-ethyl perhexanoate can be used .

In the process according to the invention, one or more chain transfer agents can also be used in a manner known per se such as hydrogen for regulating and adjusting the polymer properties and in particular the flow index can be used. The process according to the invention is continuous carried out, with either a stirred autoclave with one or more stages or a reactor Tube reactor is used, as described, for example, in DD-PS 58,387.

On the reactor outlet side, an expansion

valve and then a separating device is provided which operates under a pressure of 200 to 500 bar.

In the method according to the invention, the mixture can of polymer and monomers cooled between the expansion valve and the separator are, for example, according to FR-PS 2 313 399 by injecting ethylene at a pressure of is below the pressure of the separation device, the ethylene downstream of an exchanger of the Feedback loop can be deposited.

The ethylene copolymers of the present invention have numerous uses alone as well as in a mixture with other materials or polymers. As with the ethylene-acrylic acid ester or Ethylene-methacrylic acid ester copolymers, the properties of which are improved according to the invention, depends on the Applicability of the ethylene copolymers of the present invention through the use of the chain transfer agent obtained flow index, also from the content of units derived from maleic anhydride. An important application of the ethylene copolymers according to the invention with a flow index between 1 and 10 dg / min and 0.3 to 1 mol% derived from maleic anhydride Units lies in the film production. Corresponding films can have a thickness of 10 to 500 μm if they are made from a flat nozzle, and have a thickness of 25 to 200 μm when they are blown by extrusion are preserved. Such films are used for the production of plastic bags, food packaging, for Packaging of heavy objects as well as film material

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can be used in agriculture. Blow extrusion Such films are made with conventional devices and with a swelling coefficient between 1 and 3 as well at a pulling speed of a few 10 m / min.

The following exemplary embodiments explain the invention.

Examples 1 to 4

A cylindrical autoclave with three zones with a volume of 1 l each is used as the reactor. which is equipped with a paddle stirrer, the zones being separated from one another by valve plates are.

Fresh ethylene compressed by a first compressor is introduced into the first zone. the second zone is made with a homogeneous mixture of ethylene, maleic anhydride (MA) and ethyl acrylate (EA) supplied. In the third zone, a solution of t-butyl 2-ethyl perhexanoate in one is finally Injected hydrocarbon cut. This third zone accordingly represents the only reaction zone because in it the three comonomers and the radical initiator are in contact with one another.

In Table 1 below are the weight ratios of maleic anhydride and ethyl acrylate to ethylene in the reaction zone and the temperature

3 / -1 ι- .-. γ- / Z U λ D s-

_ 10 _

indicated in the reaction zone.

The reactor is under a pressure of 1600 bar held. At the bottom of the third zone of the reactor there is an expansion valve that allows a pressure reduction allowed to 300 bar. The mixture of molten polymer and the gaseous monomers After passing through the expansion valve, it enters a separating funnel. While the polymer accumulates at the bottom of the separating funnel, the monomers pass through a degreasing funnel to a second compressor. On the other Side is a solution of maleic anhydride in ethyl acrylate under pressure to the inlet port of a The homogenizer is introduced from the venturityp, where it is connected to the flow coming from the second compressor recycled monomers is mixed. The mixture arrives at the outlet of this venturi-like device of the three monomers to form a spiral homogenization

the

gate and is then placed in / second zone of the reactor introduced.

At the outlet of the separating funnel, the terpolymer obtained is analyzed by IR spectrometry, with the molar proportion of ethyl acrylate groups and maleic anhydride groups is determined; the corresponding Results are shown in Table 1. Furthermore, the flow index of the polymer obtained is after ASTM D 1238-73 determined; the flow index is also given in Table 1.

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The following polymer properties are then determined:

The density 9 (g / ml) according to ASTM D 2839,

the number average molecular weight M by gel permeation chromatography,

the uniformity M / M according to the same ratio

Λν Π

drive (M = the weight average molecular weight) as well as

the Vicat softening point ( ⁰ C) according to the NF T 51-012 standard (1).

The results obtained are shown in Table 2.

Example 5

Using the same equipment as in the previous examples, ethylene, Maleic anhydride and ethyl acrylate copolymerized under the following conditions:

Pressure in the reactor: 1200 bar

Temperature of the reaction zone: 180 ⁰ C.

The weight composition of the monomer mixture in the reaction zone, the molar composition of the The terpolymer obtained and its flow index are given in Table 1. The polymer is then analyzed and through its density, the numerical

characterized mean molecular weight and its uniformity, which are determined as above. the The results obtained are shown in Table 2.

Example 6

Using the same apparatus as in the previous examples, ethylene, maleic anhydride and butyl methacrylate (BMA) copolymerized under the following conditions:

Pressure in the reactor: 1800 bar

Temperature of the reaction zone: 180 ⁰ C.

The following weight ratios of the comonomers are present in the reaction zone:

4.8% BMA and 0.38% MA.

The polymer obtained has a flow index of 30 dg / min (according to ASTM D 1238-73).

Using the same equipment as in the previous examples, ethylene, Maleic anhydride and butyl acrylate (BA) copolymerized under the following conditions:

Pressure in the reactor: 2300 bar

Reaction zone temperature: 260 "C.

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The comonomers are in the reaction zone the following weight ratios:

1.3% BA and 0.23% MA.

The polymer obtained has a melt flow index of 2 dg / min (according to ASTM D 1238-73), a Vicat softening point of 65 ⁰ C and a density of 0.935 g / ml

The IR spectrometric analysis shows:

2.0 mol% of units derived from butyl acrylate and

0.8 mol% of units derived from maleic anhydride.

Example 8

From the obtained terpolymer in Example 2, a film thickness of 100 μπι is produced by extrusion-blowing at 140 ⁰ C, the pulling speed is 2.5 m / min and the Schwellkoeffizient equal to 2.

The following properties are measured on the film obtained:

2 The elastic strength in kg / cm according to the

Standard NF T 51-034 and

the breaking strength in kg / cm and the breaking elongation (%) according to the ASTM D 882-67 standard.

The following results were obtained, which are perfectly balanced in the longitudinal and transverse directions:

2 elastic strength: 51 kg / cm

2 breaking strength: 112 kg / cm

Elongation at break: 540%.

Ex iel 9

From the terpolymer obtained in Example 1, a film of 100 (in thickness under the conditions of Example 8 made.

The following properties were measured on the film:

2 elastic strength: 59 kg / cm

2 breaking strength: 100 kg / cm

Elongation at break: 450%.

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Table 1

example
No. T
( ⁰ C) reactor % EA polymer % EA Flowing in 1 230 % MA 0.85 % MA 1.3 (dg / min) 2 200 0.25 1.16 0.4 2.1 3.8 3 180 0.31 3.5 0.8 4.7 4.8 4th 175 0.30 4.4 1.0 7.7 8.2 5 180 0.84 3.6 2.1 6.7 50 0.36 1.0 200

Table 2

example
No. O 1 0 2 0 3 0 4th 0 • 5 Density γ
(g / ml) 17th , 930 17th , 936 15th , 942 9 , 960 7th , 944 M.
η 10 .500 7th .000 9 .500 8th .500 73 .850 M / M _n 81 , 0 77 , 2 , 0 , 4 , 5 Softening
point after
Vicat ( ⁰ C)

Claims (10)

Expectations 1. Ethylene copolymers with a flow index according to ASTM D 1238-73 from 1 to 500 dg / min with - 88 to 98.7 mol% of units derived from ethylene, - 1 to 10 and - 0.3 to 3 mol% of at least one of C ₁ - to C ^ -alkyl acrylates and C ₁ - to C _c -alkyl O methacrylates selected ester-derived units mol% of units derived from maleic anhydride, characterized by a uniformity M / M> 6. 2. Ethylene copolymers according to claim 1, characterized by a softening point according to Vicat of 30 to 85 ⁰ C. 3. Ethylene copolymers according to claim 1 or 2, characterized by up to 5 mol% of a further, among the C -, - to C "-" · olefins, monoalkyl maleates and dialkyl maleates, each with C ₁ - to C, - Alkyl groups, vinyl acetate and carbon monoxide selected comonomer derived units.
721-cas 5048-SF-Bk 4. ethylene copolymers according to any one of claims 1 to 3, characterized by 0.3 to 1 mol% of units derived from maleic anhydride and a flow index from 1 to 10 dg / min. 5. ethylene copolymers according to any one of claims 1 to 4, characterized by units derived from butyl methacrylate as an ester. 6. Ethylene copolymers according to one of claims 1 to 4, characterized by derived from butyl acrylate as an ester Units. 7. Ethylene copolymers according to one of claims 1 to 4, characterized by derived from ethyl acrylate as an ester Units. 8. A process for the preparation of the ethylene copolymers according to any one of claims 1 to 7 by - copolymerization of a mixture of 94 to 99% by weight of ethylene, 0.7 to 5% by weight of at least one acrylic acid and / or methacrylic acid ester and
0.2 to 0.9 wt% maleic anhydride and, if appropriate, a _{further comonomer selected from the C 3} - to Cg-00-olefins, monoalkyl maleates and dialkyl maleates with in each case C ₁ - to Cg-alkyl groups, vinyl acetate and carbon monoxide in the presence of at least one free radical initiator at 170 to 280 ^° C under a pressure of 1000 to 3000 bar, - relaxation of the reaction mixture, - Separation of the monomer mixture from the ethylene copolymer formed and - Recirculation of the separated monomer mixture to the copolymerization , characterized in that a monomer mixture is recycled that contains 99 to 99.8% Contains ethylene and 0.2 to 1% acrylic acid ester and / or methacrylic acid ester. 9. The method according to claim 8, characterized in that the radical initiator is 2-ethylhexyl peroxydicarbonate, Di-t-butyl peroxide, t-butyl perbenzoate and / or t-butyl 2-ethyl perhexanoate can be used. 10. Use of the ethylene copolymers according to any one of claims 1 to 7 for the production of films from 10 to 500 μm thick.