DE2357035B2 - Degradable olefin polymers - Google Patents

Description

C = C

R ₂

(CH ₂ ), - A

where Ri, R ₂ and R3 are identical or different and are hydrogen or a Ci-CU-alkyl radical and R _{2 is} also a COOH or a COOR group, η is an integer from 0 to 2 and A is the group -OH , -OC (O) R, -OR, -COOH, -COOR, -CN, -CONH ₂ as well as the carbazo-IyI-, pyrolidolyl or the succinimide radical and R stands for the alkyl or phenyl radical, polymerized.

2. The method according to claim 1, characterized in that the olefinically unsaturated carbonyl compound is methyl vinyl ketone or ethyl vinyl ketone is.

3. The method according to claim J and 2, characterized in that one

90 to 983 mole percent ethylene

1 to 5 mol% of the olefinically unsaturated carbonyl compound and

0.5 to 5 mol% of the olefinically unsaturated compound, the at least contains a non-paraffinic substituent,

pplymerized.

Plastics are increasingly used in a wide variety of applications Used in industry, trade and commerce. They have proven themselves particularly well as packaging material well proven. One of the many advantages that plastics have over other materials is Disadvantage that most of them are only broken down very slowly, i. H. unchanged for a long time stay before they weather. One of the few plastics that are stored outdoors, in landfills or in composting processes by occurring biological, chemical, thermal or light influences are attacked to a noticeable extent, belong z. B. some semi-synthetic cellulose esters and certain aliphatic polyesters. However, it is precisely the most commonly used bulk plastics, polyethylene, polystyrene and polyvinyl chloride that resist largely all such attacks and rot very slowly. They therefore represent a significant Pollution for the environment.

There has been no lack of attempts to develop plastics that degrade under environmental conditions will. According to DE-OS 2136 704, degradable thermoplastic materials are obtained by Mixing suitable metal complex compounds into the polymers. However, it cannot be ruled out that exuding or exuding such additives afterwards be leached, so that the use of such modified Plastics e.g. B. Food law provisions can oppose.

It is also known that the polymer chains of polymers containing C = O groups by Light influences can break up. During the irradiation UV light produces substances with a lower degree of polymerization, with the result that the starting material becomes brittle. Such polymers can be used z. B. after that described in GB-PS 11 29 793 Process by copolymerization of ethylene with CO or, as in DE-QS! 7 45 33! revealed, by Produce copolymerization of olefins with vinyl ketone.

The professional world is also known that only such

Paraffinic substances can be biodegraded, the chains of which are unbranched and not made consist of more than about 30 carbon atoms, while branched paraffins have a content of about 10 carbon atoms are no longer attacked.

Medium and high molecular weight polyolefins evade every biological attack, even if the chains contain a few percent CO or a compound containing C = O groups or a compound with a non-paraffinic side chain, e.g. B. a vinyl ester or an acrylic acid derivative are incorporated.

So it happens that olefin homopolymers (such as polyethylene, polypropylene or polystyrene) as well Olefin copolymers with monomers that have non-paraffinic side chains (such as ethylene / vinyl

acetate, ethylene / acrylic ester copolymers or ethylene / Acrylic acid / acrylic ester terpolymers) neither noticeably affected by light nor by bio-influences will. Olefin copolymers containing compounds containing carbon monoxide or C = O groups (e.g.

Ethylene / carbon monoxide or ethylene / methyl vinyl ketone copolymers) are light-degradable and become brittle under the influence of UV radiation. The resulting degradation product does not return or only returns very limited back into the biological cycle,

d. i.e. the polymers rot very slowly.

The invention therefore relates to polyolefin-based plastics which, after use, by biological, chemical or thermal influences, as they occur during composting, in a relatively short time weather. By properly controlling such a process it can be achieved that the plastics not only disintegrate mechanically, but at least partially return to the biological cycle. In this way, if necessary, even for the

to plant or animal nutrition recyclable Substances (such as peat litter or animal feed) can be synthesized.

It has been found that, surprisingly, degradable olefin polymers made from ethylene, one olefinic unsaturated carbonyl compound and another olefinically unsaturated compound containing a non-paraffinic substituent can by adding 70 to 99 mol% ethylene, 0.5 to 20

Mol% of a vinyl ketone and 0.1 to 10 mol% of one Compound of the general formula

C = C R ₂

where Ri, R2 and R3 are identical or different and are hydrogen or a QQ-alkyl radical and R2 also denotes a COOH or COOR group, η is an integer from 0 to 2 and A denotes the groups -OH, -OC (O ) R, -OR, -COOH, -COOR, -CN, -CONH2 as well as for the carbazolyl, pyrolidolyl or the succinimido radical and R for the alkyl or phenyl radical, polymerized The biological, chemical and thermal conditions prevailing in composting are degraded, especially when the attack is considerably stronger than on olefin homopolymers or olefin copolymers that contain only one of the named comonomers in addition to ethylene.

Polymers made from 90 to 98.5 mol% of ethylene and 1 to 5 mol% of one have proven to be excellent Vinyl ketones and 0.5 to 5 mol% of one of the olefinically unsaturated compounds mentioned, which are at least contain a non-paraffinic substituent.

Preferred olefinically unsaturated compounds with a non-paraffinic side chain are

Vinyl esters, such as vinyl acetate, Vinyl stearate, vinyl benzoate, Vinyl ethers, such as methylvinylaih ^ r, Acrylic compounds, such as acrylic acid, Methacrylic acid, acrylonitrile, Methacrylonitrile, acrylamide, Alkyl acrylate or alkyl methacrylate, Esters of unsaturated dicarboxylic acids, such as Diethyl maleate or dimethyl fumarate, as well

N-vinyl carbazole or N-vinyl succinimide. Because of their qualitative and quantitative composition, the polymers according to the invention have optimal chemical, optical and dielectric properties Properties on. In the case of higher molecular weight polymers, in order to achieve adequate degradability always greater contents of the cocomponents contained in addition to the olefin required than in Polymers with a lower degree of polymerization.

The preparation of the polymers according to the invention can be carried out by the customary method such as mass, Solution, precipitation, suspension or emulsion polymerization take place. The choice of the polymerization initiator and the reaction conditions are also not subject to any restrictions. Get noticed must because £. it depends on the existing copolymerization parameters and the particular reaction system may be necessary to give the reaction mixture a different molar composition than in that End product according to the invention is sought.

Polymers of the type described not only disintegrate under the influence of light, but become over it In addition, even under the conditions prevailing during composting, it is already proportionate dismantled in a short time. Irradiation of the polymer (, 5 material with a certain amount of light before or after its use can still promote degradation work, but is by no means an imperative.

The invention is illustrated in the examples below. Terpolymers and as Comparative substance consisting of two monomers copolymers and ethylene homopolymers, which in known way had been produced by the letterpress process. To test the degradability by light, the polymers were made into films and Molded press plates, with different amounts of light irradiated and the embrittlement followed visually and also measured by means of a tear test Polymers for their degradability under composting conditions took place in such a way that exposed and unexposed foils were stored in a test rott in which a mixture of drained sewage sludge and metal-free household waste at temperatures between 70 and 80 ° a composting process was carried out.

Examples

The copolymers are produced in a continuously operated laboratory ^{autoclave system, the core of which is a stirred autoclave with a capacity of 550 cm 3,} equipped with a magnetic stirrer and electric heater. The ethylene is first mixed with the gaseous additives (e.g. O2 as initiator) before it is introduced into this autoclave and then compressed in two compressors connected in series from the network pressure (approx. 5 bar) via an intermediate pressure (approx. 300 bar) to the reaction pressure. The reaction mixture then enters the autoclave via a preheater, in which the polymerization takes place at temperatures between 170 and 280 ° C. At the same time, liquid additives (such as vinyl acetate and / or methyl vinyl ketone as comonomers) can be fed into the reactor using two high-pressure metering pumps with different delivery rates. The polymer-monomer mixture emerging from the reactor is depressurized from the operating pressure to a low pressure (about 5 bar) by means of a control valve, the polymer formed mostly separating out in flaky form and being collected in interchangeable receivers.

Table 1 shows the polymers produced and their physical properties are listed. It can be seen that the mechanical property values of the terpolymers do not change very much compared to the homo- and copolymers. The tear strength decreases a little due to the incorporation of the olefinically unsaturated carbonyl compound, while the Co-component with the non-paraffinic side chain usually improves the tensile impact strength. Overall, however, the terpolymers still show the property profile characteristic of high-pressure polyethylene; they are colorless polymer compositions which can be easily processed thermoplastically, in particular into films.

To test the light degradability foils (from about 100 μπι thickness, applied to aluminum foils) and press plates (about 1 mm thick), one Subjected to UV radiation (Xenotest, Wendelauf). In the case of the foils, the amount required for embrittlement was achieved Time determined by a Einriötest. The results of this test are summarized in Table 2. The press plates were each irradiated for 1000 hours and then assessed visually according to their state of embrittlement. It was found that the homopolymers and the ethylene / vinyl acetate copolymers have not yet shown any external changes. Against it was with Ethylene / vinyl methyl ketone copolymers and the

Ethylene / vinyl acetate / vinyl methyl ketone terpolymers a hairline formation can be seen in the plates. These results show that the embrittlement cell Clearly from the carbonyl group hallway under UV influence the polymer depends and thus confirms the fact, known per se, that in olefin polymers built-in C = O groups promote light degradation.

To test for degradability through biological, chemical and thermal influences, such as those prevailing during a composting process, pressed films from about 330 to 350 μm thickness were used, partly unexposed and partly after a pre-exposure time of 10 hours (UV irradiation with a Intensity of about 145 μλν / cm ² at 200 to 280 nm, about 240 μ \ ν / αη ² at 280 to 315 nm and about 310 μW / cm ² at 315 to 400 nm). The pre-exposure time was measured so that the radiation dose was still far from sufficient to embrittle the material ) with intermittent forced ventilation (each 2 min. BeTable 1

10

15th

20 ventilation alternately with etv / a 10 min. Standstill) at temperatures of 70 to 80 ° C was subjected to a composting process. After the end of this test period, the initially colorless and almost equally thick films showed considerable changes in color, thickness and external appearance (Tahsl-

It turns out that the ethylene homopolymers and the ethylene / vinyl acetate copolymers are practical have not been subject to degradation. Also the ethylene / vinyl methyl ketone copolymers were still preserved. Particularly noteworthy, however, is the fact that all of the terpolymers listed in Table 3 are one underwent much stronger degradation than the homo- and copolymers tested. This expresses itself from the fact that all samples are no longer as foil, but only in the form of small remnants of foil from the Trial rots could be spread and the thickness of the foils also decreased significantly would have. It follows from this that the foils not only disintegrate as a result of very strong embrittlement, but that they in addition, were attacked chemically or biochemically.

Ver
search
No. Composition of
Polymers
Cocompo- cocompo-
element 1 *) element 2 **) (MoI- ⁰ /.) Enamel
index I ₂ density Stretch
span
tion Tear
firm
speed Tear
deh
tion Impact
Train-
tenacious
speed lead
end
fracture
strain Dielek
tricity
constant (MoI- ⁰ /.) _ g / lOmin g / cm ³ kp / cm ² kp / cm ² % kpcm / cm ² % 33/2 - 1.5 0.922 97 176 658 910 384 2.25 37/1 - - 1.5 0.920 102 178 677 920 414 2.25 43/1 0.7% VA - 0.6 0.920 84 185 654 1840 515 2.25 43/2 1.5% VA 1.0% VMK 0.4 0.923 75 191 814 1940 524 2.30 169/1 - 1.9% VMK 50 0.915 57 177 260 140 2.25 299/1 1.4% VME 1.8% VMK U 0.920 60 83 570 590 295 2.65 170/1 5.0% VA 20th 0.916 55 69 599 471 262 2.70

Legend: cocomponent 1 = cocomponent with non-paraffinic side chain Co-component 2 = carbonyl-containing co-component VA = vinyl acetate VMK = vinyl methyl ketone VME = vinyl methyl ether

TabeMe 2

Sample type Experiment no Content of CO or Embrittlement time Appearance of the press plates vinyl VMK of the slides acetate (MoI- ⁰ /.) (MoI-%) - (H) Homopolymers 33/1 - - 320 no cracking, colorless 37/1 - - 320 no cracking, colorless E / VA copolymers 43/1 0.7 - 320 no deformity, colorless 43/2 1.5 1.0 320 no cracking, colorless E / VMK copolymer 169/1 - 45 moderate cracking, 1.8 yellowish I / V A / VM K terpi. / ymerisat 170/1 5.0 25th severe cracking,

Table 3

Sample type

Trial No.

Church of the foils Decrease in the external appearance Foil thickness

■ xm *)

Homopolymers

E / VA copolymers

E / VMK copolymer E / VME / VMK terpolymer 299/1 E / VA / VMK terpolymer

33 / 2b **) colorless 0 completely preserved 37/1 colorless 0 completely preserved 37 / Ib colorless -10 completely preserved 43/1 colorless -10 completely preserved 43 / Ib colorless - 10 completely preserved 43/2 b colorless 0 completely preserved 69/1 pale yellow - 10 mostly received 99/1 yellow-brown -50 disintegrate into small parts 70/1 yellow -25 disintegrate into small parts

*) = original film thickness / 330-350v.m ♦ ·) = b = irradiated

Claims (1)

Patent claims: 1. Process for the production of degradable olefin polymers from ethylene, an olefinically unsaturated carbonyl compound and another olefinically unsaturated compound which contains a non-paraffinic substituent, characterized in that one 70 to 99 mol% ethylene 0.5 to 20 mol% of a vinyl ketone and 6.1 to 10 mol% of a compound of the general formula