DE1233141B - Process for the polymerization of ethylene - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C08f

German class: 39 c-25/01

Number: 1233 141

File number: E 20091IV d / 39 c

Filing date: October 25, 1960

Opened on: January 26, 1967

Polyethylene is extensively described in the literature and is commercially available in a variety made of types with different properties. These are different types of polyethylene classified and distinguished mainly by their density. The first commercially produced type of polyethylene was the so-called low density polyethylene. It is obtained, for example, by the method of U.S. Patent 2153,553. It generally has a density in the range of 0.90 to 0.935, and because of Due to its high content of amorphous polymer, it has a relatively low hardness and stiffness and a low melting point compared to more highly crystalline ethylene polymers. There were Many modifications of the process mentioned have been made in order to improve the properties of the resulting process Modify products. This includes the use of various apparatus arrangements, Catalysts and chain transfer agents.

Due to its unique properties, polyethylene is particularly useful in the field of film and packaging, with polyethylene being lower Density is more suitable for this than the medium and high density types. Polyethylene lower Density can be made into a film and has the toughness required to do so. Conventional low density polyethylene as obtained by the above process has however, only limited use in the film and packaging field because it is for it it is known that it lacks certain properties that are often desirable for this.

For example, conventional low density polyethylene, when in the form of a film, does not the transparency and clarity desired for certain applications. Numerous suggestions were made Made to improve the clarity and transparency of low density polyethylene, but none these proposals lead to completely satisfactory results.

The object of the invention is to provide a new process for the production of low density polyethylene develop that leads to products that are particularly suitable in the packaging field. In particular the products in film form should have better transparency and better gloss, lower film haze and Blocking tendency as well as higher stiffness and softening points have lower than normal polyethylene Density.

The invention relates to a process for the polymerization of ethylene at pressures of at least 500 atmospheres in two different zones, process for the polymerization of ethylene

Applicant:

Eastman Kodak Company,

Rochester, N. Y. (V. St. A.)

Representative:

Dr.-Ing. W. Wolff and H. Bartels, patent attorneys, Munich 22, Thierschstr. 8th

Named as inventor:
Samuel Briggs Vaughn jun.,
Hugh John Hagemeyer Jr.,
Longview, Tex. (V. St. A.)

Claimed priority:
V. St. v. America December 23, 1959
(861453)

wherein in the first zone at a temperature of up to 190 ° C and in the second zone at a Temperature from 190 to 270 ° C in the presence of peroxide catalysts and optionally in the presence a chain transfer agent is polymerized, which is characterized in that in the first zone, as a peroxide catalyst, is caprylic peroxide and optionally another zone in the second zone introduces organic peroxide catalyst.

Caprylyl peroxide is a commercially available compound and is made by reacting the corresponding acid chloride with sodium peroxide. So far it has not been proposed to use caprylyl peroxide to be used in a two-zone polymerization process under the conditions specified there. In addition, according to the invention, polyethylene can be used in greater yields, based on the amount used Catalyst obtained by means of conventional catalysts such as lauroyl peroxide

609 759/410

3 4

because of the solubility and stability of the catalyst, which makes the handling of the Enable catalyst.

The catalyst used according to the invention is in D. F. Doehnert and O. L. Mageli, »Evaluation of Organic Peroxides on the Basis of Half-Life Data «(preliminary version, submitted to 13th annual meeting of Reinforced Plastics Division) and has the following formula

O O

Il Il

CH ₃ - (CH 1 - C - O - O - C (CHa) ₆ CH ₃

To carry out the process, the catalyst-forming organic peroxides, to which, for example, dissolved in a suitable solvent or references include the following substances: Di-tert-butyl perdiluent, introduced into the reaction zone. oxide, p-menthane hydroperoxide, tert-butyl peroxide die The nature of the organic medium used is subject to isobutyrate, di-tert-butyl-di-perphthalate, tert-butyl-perphthalate considerable fluctuations. Usually acetate, tert-butyl perbenzoate, di-cumyl peroxide, tert-used the known inert liquid carbohydrates ao butyl hydroperoxide, diisobutyryl peroxide, methyl hydrogen. You can use catalyst concentrations of ethyl ketone peroxide, benzoyl peroxide, acetyl peroxide, Apply from 5 to 50 percent by weight in mineral oil, lauryl peroxide.

with particular advantage, however, about 20 percent by weight. The temperature in the second reaction zone varies

in a relatively low-boiling solution of 190 ° C at the beginning or top of the

medium, with the .Katalysator in the reaction as reaction zone up to 270 ° C at the withdrawal or lower

zone introduces. End of the reaction zone due to the excellent solubility. The arrangement in one

Caprylylperoxyds of the 50% ig can ^e solution even reaction vessel is carried out so that a back mixing in

handled at room temperature. This is essentially avoided in the first reaction zone

of great practical advantage as it costs less. This can be done with a single reaction vessel

Playful catalyst pumps are required and particularly due to the arrangement of a baffle between the

their provisions for handling the heated zones in conjunction with directional agitation

Catalyst are not required. Those used can be effected in the second reaction zone.

The amount of catalyst depends on the applied Reäk- The process according to the invention can in one

tion conditions and moves in general single reaction vessel with separate reaction

in the usual range. 35 zones can be carried out, preferably through

As already said, the method according to which a flow obstacle or other separating device invention is separated from one another in a two-stage or two-zone reaction. Such a second ion carried out. The temperature in the first zone zone reaction vessel is preferred. The two geliegt in the range of 130 to 190 ° C, preferably in separated reactions of the process according to the Er-range of 150 to 190 ⁰ C, the temperature while 40-making but may also be in separate Reaktionsin the second zone in the range of 190 to be carried out vessels 270 ⁰ C, held or after another and especially in the range of 190 to 25O ⁰ C embodiment, the entire procedure in a can is. single elongated, tubular reaction vessel

Which are carried out in the ethylene polymerization process.

applied pressure is 500 atmospheres and 45 A chain transfer agent can be used,

over, with a range from about 500 to 3000 Atmo- around the production of a polymer with useful

spheres is preferred. able melt index at a low reaction temperature

When performing the two-stage or two-stage allow. Suitable chain transfer agents

In the zone process, the ethylene will generally be in addition to the propane used in Example 4

the first reaction zone at 10 to 6O ⁰ C introduced. 50 for example: hydrogen; Hexachloroethane, tetra-

The temperature in the first reaction zone is chlorocarbon, chloroform; saturated halogenated

Range from 130 to 190 ° C. The preferred range is carboxylic acids and their esters, such as dichloroacetic acid

is 150 to 190 ⁰ C, measured in the middle of the first and its ethyl ester; Aldehydes such as acetaldehyde; Alkyl

Zone, and since the reaction is exothermic, esters of inorganic oxyacids of sulfur, phosphorus

usually suitable coolants for maintaining phosphorus or silicon, such as diethyl sulfite, triethyl ortho

the desired temperature. phosphate and tetrabutyl orthosilicate; as well as mercap

In a reaction vessel with a stirrer tane, such as dodecyl mercaptan.

one chooses the stirring conditions so that a maximum In the following examples one works in one

males backmixing in the first reaction zone single continuous two-zone reaction vessel, in

he follows. This is usually done by means of an intermingling between the two zones

umpteen blade or a flat-bladed turbine is kept to a minimum, so that the polymer

mixer in the upper part of the reaction zone. at two different reaction temperatures

The stream of the ethylene polymer is then placed in
a second zone is introduced where, if necessary, a. . ₁
second, different catalyst from peroxide 65 Example 1
type with additional or without additional ethylene. Suitable catalysts for zone pressure vessel, which are equipped with a stirrer for the second reaction zone, the free radicals control the temperature as well as suitable feed and

5 6

Discharges is fitted to the continuous for the catalyst a low boiling hydrocarbon feed the reactant and the continuous- material used is from the melted Borrowed removal of the reaction products to enable reaction product through the circulated borrowed. The reaction pressure is extracted to 1120 atmospheric gas flow.

Spheres set. The temperature of the inflowing 5 As can be seen from the Table, shows the product ethylene is 39 ° C at a reaction temperature, an improved stiffness and a higher Vicatin the uppermost zone of 175 ⁰ C and in the lowest softening point compared with the product according to BeiZone of 225 ° C. At a total feed rate of 2. In addition, a film produced from the product of Beikeit of 29/30 kg of ethylene per hour leads to almost no tendency to block per game 3. with a very high film transparency. Caprylyl peroxide in mineral oil as a catalyst in the
upper zone. More ethylene and 1.86 kg per

Hour of a solution of 5 percent by weight di-tert Example 4

butyl peroxide in mineral oil are used in the second

Reaction zone introduced. Under these reaction conditions one works under quite different conditions 585 kg of polymerizations are obtained per hour in the reaction vessel, but with the same cation product, which gives a yield of 574 weight catalyst and the same apparatus arrangement, share polyethylene per part by weight in the upper zone. The catalyst solution consists of a 13% strength

imported and 6300 parts by weight of polyethylene solution of caprylic peroxide in mineral oil. As a chain pro Part by weight of the transfer medium introduced into the lower zone, propane is used to produce a Means catalyst. Product with a melt index of 2 at one

The properties of the polymerization product pressure of 14/40 atmospheres and a temperature are compiled in the table and a temperature of 173 ° C can be achieved there. In the lower reaction zone Compared to a product that is in the same, no catalyst is introduced, but something becomes Apparatus arrangement with the aid of lauroyl peroxide 25 catalyst from the first reaction zone into the second (Comparative experiment 3) is obtained. The product carried along to the reaction zone.

Game 1 shows a great improvement therefrom Films in terms of transparency, gloss and polymerizates are always even better than in the case of turbidity and is similar to the comparative sample with regard to the same material that is used in the same apparatus other parameters. Has been made of great, practical order, The significance is the threefold increase in the yield.

Comparative experiment 1 Example 2

35 Work as in the previous examples,

Ethylene is compressed and introduced into a double but the catalyst for the upper reaction zone reaction vessel is as in Example 1. The pressure zone from a 5% solution of tert-butyl perbene in the reaction vessel is zoated to 1160 atmospheres in mineral oil. Put the pressure in the reaction vessel. The temperature of the inflowing ethylene is 11/95 atmospheres and because of the low 43 ° C is 40 activity of the catalyst at a reaction temperature of 160 ° C, the minimum temperature in the upper reaction zone and 260 ° C in the upper reaction zone 23O ⁰ C lower reaction zone. With a total supply with the aid of the tert-butyl perbenzoate catalyst

speed of 2920 kg of ethylene per hour leads to a product with poor opman as a catalyst of the upper zone per hour table properties, as shown in the table, 1.6 kg of a 50% solution of caprylyl peroxide in 45 the unique properties of the To highlight caprylyl peroxide of mineral oil and the second reaction zone per hour. 1.45 kg of a 5 ° / oig ^he i solution of di-tert-butyl peroxide in mineral oil to. Comparative experiment 2

Under these reaction conditions pro form

Hour 594 kg of polymerization product, which is a result booty of 750 parts by weight of polyethylene per Ge difference that a 5% tert weight part is used as a catalyst Introduced into the upper reaction zone and used butyl peracetate. There is something about it of 8200 parts by weight of polyethylene per part by weight of lower temperature in the upper reaction zone Catalyst introduced into the lower reaction zone is possible, but the optical properties of is equivalent to. 55 always film from the reaction product obtained

As can be seen from the table, the film transparency is still very poor, rence, cloudiness and gloss compared to the comparison material greatly improved. You also get a good one

Improvement with regard to the blocking tendency - Comparative experiment 3

talking films, as well as another yield- 60

improvement as well as greater stiffness and one polymerizes ethylene analogously to the previous higher ones Vicat softening point. examples below those given in the table Conditions with the difference that one is used as a catalyst for the upper reaction zone Example 3 65 lauroyl peroxide used.

The table shows the poor optical properties

The procedure is analogous to Example 2, as shown in the table also for that made from this product shown, with the difference that as a solvent Firms.

7th 1 1120 Examples 2 3 I.
1160 4th , 8th Comparative experiments 1 2 3 1160 1440 1195 1075 1100 39 37 Reaction pressure in atm 43 42 13th 44 41 38 Inlet temperature of the ethylene 175 160 in ⁰ C 255 160 260 173 230 210 190 Reaction temperature in ° C 260 202 249 249 250 the upper reaction zone 2920 2980 the lower reaction zone 585 2920 603 2860 603 2450 2490 4080 Hourly sales 594 431 467 435 821 supplied ethylene in kg 8.1 3.8 polyethylene produced in kg 9 * 1.6 5.5 - 4.9 not 11.4 Ka introduced into the upper zone measured catalyst solution in kg 1.9 1.5 2.03 1.5 0.930 2.3 2.6 introduced into the lower zone 2170 Catalyst solution in kg 13th 20th 108 Concentration of the catalyst in 5 50 5 580 5 5 18th Weight percent 5 62 5 5 5 in the upper zone 5.5 in the lower zone 3 Yield in parts by weight 574 790 Polyethylene 750 1900 not 400 per part by weight in the upper zone measured imported catalyst 6300 8400 8200 4000 not 6400 per part by weight in the lower 1.56 1.65 measured Zone of introduced catalyst. 0.9250 1.7 0.9255 1.31 2.6 1.7 1330 0.9250 1540 0.920 0.920 0.923 Melt index, g / 10 min 98 1470 101 1100 1070 1300 density 610 100 510 93.0 91.0 98 Stiffness in kg per cm ^a 72.7 560 64 100 10 150 Vicat softening point in ° C 4.3 68 6th 29.9 16.4 48.8 Fihntransparency in cm 4th 5.2 2 18.9 34.9 8.1 Film gloss in ° / ₀ 3 2 2 3 Film turbidity in ° / ₀ Blocking value of the film

The melt index given in the table was determined according to the test method ASTM-D-1238-52 T of American Society for Testing Materials determined as follows:

In a cylinder of an extrusion press provided with a certain mouthpiece opening, certain Mass in which a movable piston is arranged and which is kept at a temperature of 190 ° C 3 g of the polyethylene sample to be examined are introduced. The sample is then using the Plunger pressed out through the mouthpiece opening. The weight of one during an extrusion time of 6 minutes The piece obtained χ 1.64 is equal to the melt index. This term is used to describe the outflow velocity to be understood in grams per minute.

The film transparency was determined as follows: Between two ring-shaped panes of window glass a film of a certain thickness of the polyethylene to be examined is placed. Behind the film there will be a Reading sample in the direction of the observer who is a certain distance in front of the film, moved until letters of a standard size can be distinguished by visual observation.

The distance read in centimeters is the film transparency.

Film gloss was determined using the American Society for Testing Materials test method ASTM-C-346-59 certainly. The film gloss is defined as the percentage of that reflected from the film surface Light at an angle of incidence of the light of 45 °.

The film haze was determined by the test method

ASTM-D-1003 from the American Society for Testing Materials certainly. The film opacity is defined as the percentage of the light from a light beam, which is scattered when the light beam passes through the sample to be tested.

Comparative experiments 4 and 5

Ethylene is polymerized under the following conditions:

First zone temperature 170 ° C

Temperature of the second zone 183 ⁰ C

Ethylene pressure 1430 at

Diisopropyl peroxydicarbonate was used as a catalyst in the first zone introduced. No catalyst was introduced into the second zone. In comparison experiment 4 the ethylene contained 5.1% and in comparative experiment 5 4.4% propane. The obtained polyethylenes possessed following properties:

Comparative
Attempt 4 Comparative
attempt 5 Melt index
density 1.6
0.932
2495
110
5
21
30th 2.0
0.932
2222
107
3
27
19th Stiffness in kg / cm ²
Softening point after
Vicat
Film transparency in% ...
Film haze in%
Film gloss in%

Comparative experiments 6 and 7

Ethylene is polymerized under the following conditions:

First zone temperature 160 ° C

Second zone temperature 257 ° C

Ethylene pressure 1395 to 1235 at.

Diisopropyl peroxydicarbonate was used as a catalyst in the first zone and introduced into the second zone di-tert-butyl peroxide. Contained in comparative experiment 6 the ethylene used for the polymerization 2.9% propane and in experiment 7 1.1% propane as Chain transfer agent. The polyethylene obtained had the following properties:

Comparison
attempt 6 Comparative
attempt 7 Melt index
density 1.5
0.929
11
17th
36 1.8
0.927
36
9
54 Film transparency in% ...
Film haze in%
Film gloss in%

Comparing the results obtained with the results from the table above, it gives clearly show that the properties of the polyethylene produced by the process of the invention are better than the polyethylenes produced by the known process. Furthermore, it turns out that the addition of a chain transfer agent in the known process has a negative effect on the film transparency, Film cloudiness and gloss.

The ethylene polymers prepared according to the invention are primarily intended for the production of highly transparent, glossy films. Such movies can be used for packing new clothes, for making bags for textiles and for use in Serve dry cleaning businesses. These fumes have a better notch toughness than so-called polyethylene medium and high density. They are also easy to thin at high manufacturing speeds Peel off films. Their extremely strong shine and high light transmission give them packed Products a pleasing appearance. The polymers prepared according to the invention show an improved Combination of properties compared to previously available types of polyethylene.

Claims (4)

Patent claims: 1. A process for the polymerization of ethylene at pressures of at least 500 atmospheres in two distinct zones, wherein in the first zone at a temperature from 130 to 190 ⁰ C and in the second zone at a temperature of 190 to 270 ° C in the presence of Peroxydkatalysatoren and optionally polymerizing in the presence of a chain transfer agent, characterized in that caprylyl peroxide is introduced into the first zone as the peroxide catalyst and, if appropriate, another organic peroxide catalyst is introduced into the second zone. 2. The method according to claim 1, characterized in that the caprylyl peroxide is in the form a 5 to 50% solution in an inert organic Feeds solvent into the first polymerization zone. 3. Process according to Claims 1 and 2, characterized in that di-tert-butyl peroxide is optionally introduced into the second zone as a catalyst. 4. Process according to Claims 1 to 3, characterized in that at pressures of 1120 polymerized to 1160 atmospheres. Considered publications:
Opened documents of French patent no. 1207 723;
Modem Plastics, February 1959, pp. 142 to 148.