DE1121808B - Process for the production of copolymers from ethylene and butene-1 - Google Patents

Description

The use of »Ziegler catalysts« in the production of polymers from ethylene, Propylene etc. has grown in importance very quickly, especially because of these catalysts allow the polymerization to be carried out at or near atmospheric pressure. In contrast to required the production of plastic olefin polymers before the discovery of the Ziegler catalysts the use of very high pressures during the polymerization.

The significant process advantages of the low pressure polymerization process according to Ziegler, however, are at least partially due to certain considerable qualitative disadvantages of the low-pressure polyethylene obtained bought in comparison to the high-pressure polyethylenes. When the molecular weights are equal the low pressure propyl propylene and polybutene are even inferior in this regard. In particular the Ziegler low-pressure polymers were generally relatively proportionate high rigidity compared to conventional high-pressure polyethylenes characterized by the same tensile strength. As a result, so far if a low pressure polyethylene with high flexibility was desirable at low temperatures, this result only at the expense of a considerably lower one Tensile strength can be achieved, d. H. that the polymerization conditions had to be regulated so that a polymer having a relatively low molecular weight was prepared.

The object of the invention is to produce superior ethylene copolymers with a high Flexibility equivalent to that of a high pressure polyethylene of comparable tensile strength or it surpasses.

The invention relates to a process for the production of ethylene copolymers by Polymerization of a mixture of ethylene and 0.2 to 10 percent by volume of butene-1, based on the Mixture, in the presence of one of an aluminum trialkyl, an aluminum triaryl or an alkyl or Arylaluminum halide and a reducible compound of metals from subgroups IV to VIII produced polymerization catalyst.

Surprisingly, despite the improvement in the relatively poor flexural properties of the homopolymers of the higher ethylene homologues, e.g. B. polypropylene, largely amorphous ethylene polymers with unusual high degree of flexibility. You can use the said catalysts at low pressure both at normal and low temperatures for the preparation process

of copolymers made of ethylene

and butene-1

Applicant:

Esso Research and Engineering Company,
Elizabeth, N. J. (V. St. A.)

Representative:

Dr. W. Beil and A. Hoeppener, lawyers,
Frankfurt / M.-Höchst, Antoniterstr. 36

Claimed priority:
V. St. v. America April 17, 1957 (No. 653 380)

Lewis W. Bowman, Westfield, NJ (V. St. A.),
has been named as the inventor

getting produced. The desired results are made up by polymerizing an olefinic mixture 0.2 to 10 percent by volume, preferably 1 to 5 percent by volume of 1-butene and correspondingly 90 to 99.8 percent by volume or preferably 95 to 99 volume percent ethylene achieved. If the butene concentration of the monomer mixture is above 10%, the product would become increasingly rubbery, soft and sticky and in this form for various areas of application, e.g. B. for shaped objects, unsuitable be.

The copolymers which can be prepared according to the invention are relatively amorphous resins which have a considerable number of chain branches (approximately one ethyl branch for every mole of bound butene) and a correspondingly low crystallinity. They are characterized by a tensile strength of about 175.78 to 351.56 kg / cm ² , a molecular weight between about 50,000 and 500,000 (Harris formula) and a torsional modulus between about 0.002 · 10 ⁵ and 0.035 · 10 ⁵ kg / cm ² at 25 ⁰ C and not more than 0.084 x 10 ⁵ kg / cm ² at -50 ⁰ C. They are characterized in particular within the specified molecular weight range by a surprisingly small torsion. Products with molecular weights below 50,000 have too great a negative

109 759/440

3 4

brittleness, so that they can be maintained as plastics by temperature and pressure,

would be of great interest, whereas with molecular to keep the solvent in the liquid phase,

Weighing in excess of 500,000 the products tend to be used in the manufacture of the catalyst

for extrusion or similar processes if the two solutions are too high mixed so that an Al: Ti-MoI-

Melting temperatures. 5 ratio between about 0.6: 1 and 3: 1 is created.

The drawing explains the unusual bending. Preference is given to Al: Ti ratios between approximately the degree of sameness of the ι _: i prepared according to the invention and 2: 1, since with these large polymerization ethylene-butene-1 copolymers can be achieved compared to speeds. If, on the other hand, related polymers of comparable tensile products of relatively low molecular strength are desired, then Al: Ti ratios are desired

With the exception of the critical composition of between 0.6: 1 and 0.9: 1, in spite of the fact that in the case of olefin mixtures, the polymerization is carried out in a relatively low polymerization manner that usually occurs in them, e.g. B. according to the laid out documents of the speeds. Catalyst production is carried out in Belgian patent 533 362, at low pressure usually at temperatures between about 0 and 0. Here are particular combinations of 15 10O ⁰ C, preferably between about 20 and 50 ⁰ C, and polymerization conditions as will be set forth, carried out a pressure sufficient to make the preferred. to keep organic solvents in the liquid phase.

Catalysts which are of particular use in the invention are prepared by the fact that, if aged, prior to use, e.g. B. when titanium tetrachloride with the help of an aluminum ao 30 to 100 ⁰ C for 10 to 60 minutes,
alkyl or aryl compound to a customary titanium The catalyst can be reduced with the olefin mixture in connection with a valence between about 2.0 in a polymerization vessel, usually in the presence and 3, preferably 2.1 and 2.9. The aluminum compounds preferred for and also for this purpose by additional inert diluent in the presence of an additional amount of the aluminum will be mixed by the formula 35 alkyl compound. It is desirable

the catalyst in the polymerization zone at a

χ R concentration of about 0.05 to 0.5% in particular

Al-R ' about 0.15 to 0.3%> calculated as the total amount

\ Metal compound with reference to the total

3 »liquid to use. The polymerizable monomer mixtures are advantageously in

shown in which R, R 'and XC _r to Cg-alkyl or a concentration of about 2 to 20 weight

Are aryl groups. X can also be a halogen, in percent, based on the total amount of liquid,

be a particular chlorine, although it is used with such, so that a sufficiently liquid reaction

Halogen-alkyl compounds is more difficult to obtain the titanium 35 product. However, it can also be higher

can be applied to the preferred valence below 3 to re-monomer concentrations, in particular

duck. Examples of reducing agents are aluminum, especially if the conversions are so limited

miniumtriethyl, aluminum diethyl chloride, aluminum, that enough unconverted mono-

ethyl sesquichloride, aluminum triisopropyl, triisomer mixture remains, in order to

butyl, -tri-n-octyl, -triphenyl. 40 handling of the polymerized mixture.

These catalysts are known to be used in the The polymerization temperature is generally

Art produced that a reducible compound at about 0 to 100 ⁰ C, preferably 40 to 85 ° C, ins-

of a transition metal of groups IV to VIII of the particular 60 to 80 ° C, and the pressure is

Periodic system and one of the possible ones - advantageously between about 1 at and 35 atu, especially

the organoaluminum compounds separated in 45 between 1 atm and 3.5 atm.

an inert hydrocarbon dissolves, said solutions suitable polymerization conditions are obtained particularly that the metal compound are in an at temperatures of about 75 ⁰ C, catalyst concentration / contain from about 0.05 to 5.0 ° o, and concentrations of about 0, 2% and a catalyst then mixes the two solutions and in a tor-ΑΙ: Ti molar ratio of 1.5. Higher catalyst inert atmosphere agitates, a solid precipitate is formed, and higher temperatures tend to form any reduced heavy metal compound. The reason for this is to lower the molecular weight of the polymeric mixture or precipitate obtained by the precipitated product. Therefore, with relatively solid catalyst, some free aluminum alkyl and moderately high catalyst concentrations, it may be appropriate to contain the inert organic solvent, then it will be brought into contact with the olefin mixture to operate at relatively low polymerization temperatures, and vice versa.

then at atmospheric or approximately atmospheric It is convenient to use solvents and monomers

chemical pressure is polymerized. of high purity, in particular

The substances used in the manufacture of the catalyst with regard to oxygen and sulfur-containing

Deten inert liquid solvent can C ₃ - to impurities, z. B. air, water, alcohols, mercap

C ₁₈ - and higher paraffins, cycloalkanes or aromatics 60 tane, as all these impurities are the catalyst

be. Examples of such solvents are propane, poison. The liquid reactants become

n-pentane, N-heptane, N-dodecane, acid-treated z. B. by distillation, treatment with sodium

or otherwise highly refined petroleum or activated silica or clay, washing with

Fractions in the gasoline, kerosene or gas oil sector cleaned aluminum alkyl solutions. The Rea-

(z. B. with a boiling range up to about 300 ⁰ C at 65 tion vessels are prior to use with a

atmospheric pressure). If gas-inert gas, such as nitrogen or methane, is normally blown out,

shaped solvents, e.g. B. propane or isobutane, If the polymerization is up to the desired

be used, a suitable combination of the degree of conversion must have progressed, the re-

action-like ζ. B. with a C ₁ - to C ₈ alkanol such as methanol, isopropanol, n-butanol or isooctyl alcohol, then the precipitated solid polymer particles from the liquid z. B. separated by filtration. Metal-containing residues are then removed by washing the separated polymer with liquid oxygen compounds, such as the abovementioned alcohols or ketones, for example acetone, methyl ethyl ketone, acetylacetone, and / or with acids, e.g. B. hydrochloric acid removed. Finally, the polymer is dried, pressed and packaged in a known manner.

Examples

A 2 percent aluminum triethyl solution in dry n-heptane was added to a 2 percent TiCl ₄ solution (in n-heptane) at room temperature in a reaction vessel blown out with dry nitrogen. The solutions of the two metal compounds were mixed with one another in such a way that a mixture with an AlAt ₃ : TiC ^ molar ratio of 1.5 and a concentration of the total metal compounds of 15 g per liter was obtained. After stirring for 15 minutes, the catalyst slurry obtained was drawn off under nitrogen and placed in a reaction flask which contained 1 liter of n-heptane which had been saturated with the olefin mixture ^{at 25 ° C. and 1 atm.} The polymerization was then allowed to proceed at atmospheric pressure. The ratio of ethylene to butene, the catalyst concentrations and other variables such as e.g. B. the polymerization time and temperature are given together with the associated product properties for each experiment in Table 1 below.

Once the desired degree of polymerization was reached, the reaction mixture was diluted with an equal volume of isopropyl alcohol, the polymer was separated from the liquid by filtration, boiled with a solution of 2 ° / ₀ acetylacetone in isopropyl alcohol, refiltered and dried.

Table I.

2 Trial number 3 4 *) 5 *) 6 *) 7 ») 1 2.0 2.0 (A) (A) (B) (C) 2.0 1.5 1.5 1.5 1.5 1.5 no 1.5 0.45 0.18 0.09 0.18 0.09 0.09 0.304 1.22 0.608 1.22 0.608 - 0.608 50 75 50 75 50 - 50 1.0 0.5 1.0 0.5 1.0 -. 1.0 222 166 232 166 262 - 239 0.1 2.8 0.1 2.7 0.1 - 0.3 1000 200 410 185 1000 23 470 295.30 207.41 258.74 208.82 267.18 123.04 234.13 540 550 550 650 610 630 500 26.73 4.92 18.28 16.66 56.25 14.06 6.61

Use: Percent by volume of butene-1 in ethylene

AlAt ₃ : TiCl ₄ ratio

Catalyst concentration in percent by weight

Total weight of the catalyst in grams

Temperature, ⁰ C

Duration of the experiment in hours

Speed in g polymer / hour / g cat. Weight percent oily polymer

Production characteristics

Molecular weight ■ 10 ~ ³ (D)

Tensile strength, kg / cm ²

Strain, %

Torsional modulus at 25 ° C, kg / cm ² **)

(A) 2 "I ₀ propylene in ethylene; (B) 100% ethylene; (C) conventional high pressure polymethylene. (D) determined by inherent viscosity using the Harris formula. *) Experiments 4 to 7 are comparative experiments or comparative values. **) ASTM method D 1043-51.

In all runs 1 to 3 the reaction rates were excellent. It wasn't adverse film formation was found on the walls of the reaction vessel, and the yields of oily Polymer were very small. In addition, it was found that by appropriately varying the reaction temperature and the catalyst concentration is possible, the molecular weight and thereby all change related physical properties of the product as desired, where polymers were obtained whose molecular weight between 50,000 (not listed in the table) and 1,000,000 (Experiment No. 2) and above. A particularly good union of machinability, The strength and flexibility of polymers with a molecular weight between 100,000 and received 500,000. In contrast, the analogous ethylene-propylene copolymers were the same Tensile strengths much more rigid (tests 4 and 5). This great rigidity was observed in the case of the unbranched low-pressure polyethylene (experiment no. 6) emphasized even more. The usual high pressure polyethylene (Polymer No. 7) was despite its low molecular weight and correspondingly low Tensile strength relatively inflexible and almost as rigid as the much higher molecular ethylene-butene mixed polymer (Molecular weight equal to 1,000,000) of Experiment No. 2.

This superior flexibility of the ethylene-butene copolymers which can be prepared according to the invention is at lower temperatures even more surprising and makes the present interpolymers special for use at low temperatures, e.g. B. as cable insulators, suitable. This is done by the in Table 2 explains the elasticity data compiled.

Table 2
Flexibility at low temperatures

3 Trial number 6 *) 8th*) Ethylene
plus 2 »/" 0.016663 Polyethylene
after Poly
propylene 5 0.047811 5 *) Composition of the polymer Propylene 0.024399 Ziegler Il clC Π
Ziegler (E) 0.049220 test Torsional modulus, 0.036561 kg / cm ² x 10 0.052732 temperature Ethylene
plus 0.004922 0.054841 0.05625 0.126580 2 ^e / o butene 0.006820 0.078044 0.084372 0.203899 0.011250 0.11461 0.099840 0.295302 ⁰ C 0.017578 0.126580 25th 0.026366 0.163119 15th 0.063279 0.177181 0 -15 -25 -50

(E) Molecular weight 150,000, tensile strength 210 kg / cm ² .
·) Comparison tests or comparison values.

The properties of the ethylene-butene copolymers produced according to the invention are indeed excellent. They are as flexible at -50 ° C as typical polyethylene and polypropylene with comparable tensile strength at room temperature. The advantageous properties that the new copolymers have at low temperatures are particularly great compared to the propylene homopolymer, whose rapidly increasing rigidity at temperatures below 0 ^° C. is known. It should be noted, however, that the butene copolymers obtained according to the invention are about as flexible at -15 ° C as the corresponding propylene copolymers at -15 ° C., even compared to the ethylene-propylene copolymers, which are decidedly superior to the ethylene and propylene homopolymers Room temperature.

Claims (3)

PATENT CLAIMS: 1. Process for the preparation of copolymers by polymerizing a mixture of ethylene and butene-1 in the presence of a polymerization catalyst prepared from an aluminum trialkyl, an aluminum triaryl or an alkyl or aryl aluminum halide and a reducible compound of metals of subgroups IV to VIII, characterized in that mixtures of 90 to 99.8 percent by volume Ethylene and 0.2 to 10 percent by volume butene-1 are polymerized. 2. The method according to claim 1, characterized gekennao that the polymerization is carried out in the presence a catalyst carried out by reacting a mixture of 1 mole of titanium tetrahalide and 0.6 to 3 moles of an aluminum alkyl compound having 2 to 8 carbon atoms each Alkyl group has been obtained. 3. The method according to claim 1, characterized in that the polymerization is carried out in the presence a catalyst carried out by reacting a mixture of 1 mole of titanium tetrachloride and 1 to 2 moles of aluminum triethyl has been obtained. Considered publications:
Opened documents of Belgian patent No. 538 782. 1 sheet of drawings θ 109 759/440 1.62