DE1645024C - Process for the production of ethylene copolymers - Google Patents

Description

H or (CH ₃ )

I H

H, C- = C-N

wherein R ₁ denotes an alkyl radical with up to 8 carbon atoms.

2. The method according to claim 1, characterized gekennzeicnnet that the copolymer is 85 to 98 mol percent Ethylene, 1 to 5 mole percent of the vinyl ether and 1 to 10 mole percent of the amide.

5. The method according to claim 1, characterized in that the amide is N-isopropyl acrylamide or N-tert-butyl acrylamide is used.

4. The method according to claim 1, characterized in that the vinyl ether is vinyl methyl ether.

The invention relates to a process for the production of copolymers of ethylene.

High molecular weight solid polymers made from ethylene are known which, due to their good physical and chemical properties, are used in many different ways. The preparation can take place in that ethylene is polymerized for the polymerization at a pressure of 250 to 4200 atm and a temperature of 100 to 400 ^° C. in the presence of a free radical initiator. The properties of the polymers can be controlled to a certain extent by changing the polymerization conditions and by using various initiators. The properties such as density, molecular weight, melt index, tensile strength, rigidity and surface properties can be influenced further by using so-called modifiers and / or by polymerizing the ethylene with small amounts of comonomers. So was z. B. proposed to polymerize ethylene in admixture with vinyl alkyl ethers, such as methyl vinyl ether, and in this way to produce an end product that is tougher than polyethylene and from which thin blown films can be made that are less cloudy than thin films made of polyethylenes . Although the copolymers produced are satisfactory for some applications, a lack of sufficient toughness and rigidity is felt to be very disadvantageous for other applications.

Based on this prior art, it is therefore an object of the invention to provide a copolymer of ethylene to produce, which has a high toughness and a stiffness that is comparable or are better than those made of polyethylene produced under the same conditions.

According to the claimed process, ethylene is copolymerized at pressures of 350 to 4200 atm and temperatures of 100 to 400 ^° C. in the presence of a catalyst which forms free radicals and optionally customary modifiers. The process is characterized in that such amounts of monomers are used that the copolymer is 70 to 98.5 mol percent ethylene. 1 to 10 mol percent of a vinyl ether and 0.5 to 20 mol percent of unsubstituted acrylic or methacrylamides or their N-monoalkyl derivatives of the general formula

H or (CH ₃ )

H
H, C = C-N

wherein R ₁ denotes an alkyl radical with up to 8 carbon atoms.
The following compounds are mentioned as examples of ethers which are particularly advantageous: methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, tert-butyl vinyl ether, N-butyl vinyl ether, tobutyl vinyl ether, octyl vinyl ether, hydroxymethyl vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, hydroxybutyl vinyl ether, hydroxybutyl vinyl ether, isobutyl vinyl ether, octyl vinyl ether, hydroxymethyl vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, hydroxybutyl vinyl ether.

As examples of particularly advantageous use The following compounds are called amides: acrylamide, N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-isopropylacrylamide, N-tert-butyl acrylamide, N-amyl acrylamide, N-tert-octobyl amide and methacrylamide.

It has been shown that the addition of unsubstituted and certain substituted \ crylamides and Methacrylamides are the third component to which ethylene and ether form an end product leaves that is tougher than ethylene / ether copolymers. Thick samples of ethylene / ether / acrylamide copolymers have a transparency that is comparable to that of polyethylene films, while Samples of comparable thickness made of polyethylene or of ethylene / ether copolymers opaque are. The copolymers produced in this way are also more rigid than the known ones when an amide sufficient amount is added. The application of amounts that are outside the narrow, im claimed Area mentioned, lie, affects the rigidity and rigidity of the polymers, and rubber-like material is obtained.

The ethylene content has a preferred range of 85 to 98 mole percent. The content of vinyl ether is preferably 1 to 5 mole percent. The unsaturated amide content is preferably from 1 to 10 mole percent.

The process according to the invention is preferably carried out at a pressure of 1400 to 2450 atm. The temperature is preferably 130 to 300 ^° C.

In general, the catalyst concentration is 0.0005 to 2%, based on the total weight of the Monomers in the polymerization reaction space.

So-called modifiers or chain transfer agents can also be used to adjust the properties in a desired manner to influence the polymers. Examples are: aliphatic alcohols with 1 to 10, preferably 3 to 5 carbon atoms such as acetone, diethyl ketone, methyl isopropyl ketone and the like, saturated aliphatic Aldehydes with 1 to 8, preferably 2 to 5 carbon atoms, such as formaldehyde, acetaldehyde, butyraldehyde and the like, saturated hydrocarbons such as ethane, propane. Cyclohexane and similar, aromatic hydrocarbons, how great.". 1. Xylene and similar chlorinated hydrocarbons, such as chloroform, carbon tetrachloride and the like, as well as hydrogen.

The process according to the invention can be carried out either continuously or batchwise. However, a continuous operation is preferred, with the ethylene, the amide comonomer, the vinyl ether comonomer, the initiator and the modifier - if one is used
be fed to a reaction space which has suitable temperature and pressure conditions. The copolymer is deposited continuously from the reactor outlet, and d; "Part of the monomers, the initiator and the Mclifikators which has not participated in the reaction, ⁵ we- recycled back into the reaction space.

The following exemplary embodiment serves to explain the invention in more detail, in which all percentage Data are mole percent, unless expressly stated otherwise.

Attempts have been made in which ethylene was polymerized together with small amounts of vinyl ether and an acrylamide or an N-substituted acrylamide. In each experiment, a steel reaction vessel and all accessories were carefully cleaned with ethylene and washed to remove all traces of air or oxygen. The normally gaseous substances, such as ethylene and propane, which act as modifiers. w ere introduced into the reaction chamber of Reaktionsgefaßes, u ~ »at atmospheric pressure at a temperature of 130 ⁰ C was obtained. The introduction of the starting materials was carried out until a pressure of 49 a 'was reached. continued. "Hot ethylene was then pumped into the reaction vessel until the pressure reached a value of 525 at at a temperature of 130 ^° C. A mechanical stirrer was then operated inside the reaction vessel, and the normally liquid starting materials - liquid comonomers, comonomer solutions , Di-terL-butyl-peroxide initiator, dissolved in benzene - were pressed into the reaction chamber by high-pressure ethylene from a small, cold chamber in the reaction vessel, where they had been kept free from any influence of oxygen or air, until a final pressure of 1400 at 130 ° C. After the desired reaction time, the pressure was released from the reaction vessel and the copolymer could be removed as the end product and its properties could be determined.

The reaction conditions for the individual experiments are shown in Table I below. Table II relates to the physical properties of the copolymers obtained according to the conditions according to Table I. The methods for determining the melt index and density are in J. App. Polymer Sci. 8, 839 (1964) and J. Polymer Sci. A-2, 1301 (1964). All other evaluations were carried out using 0.5 mm thick samples. The impact strength or notched impact strength was determined according to the method ASTM D-1822 61 T with the aid of S-specimens. L-samples were used at a slow trial speed. In an Insiron tearing machine, the de-tension was increased until the sample broke at a speed of 5 cm / min. The modulus (5% secant. Extrapolation of the initial part of the stress-strain curve), the yield point and the breaking strength were determined from the stress-strain curve. The turbidity and the degree of transparency were determined on 0.55 mm samples according to Method A of ASTM-1003-61. With one exception, the composition of the polymers was determined on the basis of the elemental decomposition analysis. In the exceptional case mentioned, the polymer in question contained a ^{monomer mixed with C 14} and was analyzed with the aid of scintillation counting.

From the values in Table II it can be seen that the addition of acrylamide to your ethylene / vinyl ether copolymer the tensile strength, the impact strength, the stiffness and also the optical Properties - greater transparency - significantly improved.

Table I.

I DTBP *)

Try i minor

Comparative experiment

Comparative experiment

2.1
*) Di-tert-butyl peroxide.

2.1
6.2
2.1

C ₂ H,

V.

84.2
83.5
87.2
82.3

ether ° /. benzene
(Solution
middle door
Initiator)
% Amide - - CH ₃ OH
(Solution
medium
Door amid) e, H "
% Reak
tion time
(Min.) Around
settlement
(Ge
weight
percent) Vinyl methyl 1.3 0.2 N-isopropyl
acrylamide 0.2 - 14.4 60 8.4 Vinyl methyl
Vinyl t-butyl 1.4
0.9 0.2
0.2 N-tert-butyl
acrylamide 0.6 0.5 14.2
11.8 24
39 6.9
9.9 Vinyl t-butyl 0.9 0.2 7.0 9.1 38 12.7

I 645 024

continuation

attempt DTBP *)
minor C ₂ H, ether 1.9 tsenzui
(Solution
mitle! for Amide % CH ₃ OH
(Solution
medium C ₃ H ₈ Reak
tion time Around
settlement
(Ge (XlO- ¹ I. Initiator) for amide) weight % 1.9 % Acrylamide % (Min.) percent) Comparison 2.1 94.5 Vinyl hydroxy 0.2 - 3.5 - 47 10.0 attempt butyl 3 2.1 94.6 Vinyl hydroxy 0.2 0.2 3.2 - 43 7.0 butyl

·) Di-tert-butyl peroxide.

Table II

Pol'merisa! ether Amides Enamel
index module density Stretch
border fracture
strength Blow
strength Cloudiness attempt Composition,% % % C ₂ H ₄ 1.3 _ (dg min. » (kpcnr) (g cm ³ ) (kp cm-) (kp / cm ² ) (kp cm ') ⁰ O % 0.7 174 *) 153 249 4th 67 Comparison 98.7 1.5 1.7 attempt 0.9 - 4.9 195 , 933 IK ' 192 5.2 58 1 96.8 56 199 .940 175 154 1.1 76 Comparison 99.1 1.1 4.0 attempt U - 65 194 , 934 145 186 4.5 47 2 94.9 0.4 144 *) 130 269 8.8 57 Comparison 98.9 1.1 1.5 attempt 0.4 '38 *) 124 272 10.4 32 3 97.4

*) Not measured,
dg = decigram.

The copolymers produced according to the invention can be used alone or in a mixture with other thermoplastic Polymers for the production of foils, molds. Bottles and similar items used will. Fillers, stiffening materials such as fibers and foaming agents can be used in certain applications can be added. Another influence on the properties of the end products is possible through the addition of stabilizers and pigments, whereby z. B. also completely different colors can be achieved.

Claims (1)

! 645 claims: 1. Process for the production of ethylene copolymers at pressures from 350 to 4200 at and temperatures from 100 to 400 ° C in the presence of a free radical forming catalyst and optionally customary modifiers, characterized in that such amounts of monomers are used that the copolymer is 70 to 98.5 mol percent Ethylene, 1 to 10 mole percent of a vinyl ether and 0.5 to 20 mole percent unsubstituted acrylic or methacrylamides or their N-monoalkyl derivatives of the general formula! 5