AU627327B2

AU627327B2 - Degradable polymer mixtures

Info

Publication number: AU627327B2
Application number: AU57843/90A
Authority: AU
Inventors: John Dr. Hobes; Wolfgang Dr. Payer
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1989-06-28
Filing date: 1990-06-27
Publication date: 1992-08-20
Anticipated expiration: 2010-06-27
Also published as: AU5784390A; CN1048395A; KR910000891A; EP0407762A1; CA2019934A1; JPH0339340A; ZA904835B; DE3921144A1

Description

WATERMARK PATENT TRADEMARK \TTORNEYS Fi: :II, -~rli

C'

Form COMMONWEALTH OF AUSTPALIA PATENTS ACT 1952-69 COMPLETE SPEC9FICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art t.

,Name of Applicant: Address of Applicant: S Actual Inventor; Address for Service HOECHST AKTIENGESELLSCHAFT 50 Bruningstrasse., D-6230 Frankfurt/Main 80, Federal Republic of Germany JOHN HOBES and WOLFGANG PAYER WATERMARK PATENT TRADEMARK ATTORNEYS.

LOCKED BAG NO. 5, HAWTHORN, VICTORIA 3122, AUSTRALIA Complete Specification for the invention entitled: DEGRADABLE POLYMER MIXIURES The following statement is a full description of this invention, including the best method of performing it known to 1.

lis 11S 4 iV Sgnaturc. To: THE COMMISS ONER OF PATENTF Dr Karl-Hein Reichelt /1 Procuris of Netld "tr&S Hoechst Aktiengesellsch aft) =i i:.

Ier Degradable polymer mixtures The present invention relates to photodegradable polymer mixtures, a process for the preparation thereof, and the use thereof as a film material.

Plastics are employed to a constantly increasing extent for a very wide variety of applications in industry, business and commerce. They have proves highly successful, in particular as a packaging material. However, the numerous advantages which plastics have over other materials are countered by a disadvantage, n, ,ely the low degradability. Plastics remain unchanged for a long period before weathering. In most cases, degradation takes place only very slowly.

S

Se 0080 *0 to *DoS i o. 15 s* S* 0 0 a 64 25 Only few plastics are attacked to a notable extent by biological, chemical, thermal or photochemical processes which occur on storage in the open, in dumps or on composting. These include some semisynthetic cellulose esters and certain aliphatic polyesters.

However, very frequently used consumer plastics, such as polyolefins, substantially resist degradation processes of this type and decompose only very slowly. They are therefore a not inconsiderable environmental pollutant.

A summary concerning polyolefins can be found in Ullmanns Encyklopadie der technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], 4th Edition, Verlag Chemie, Weinheim-Basel, 1980, volume 19, pages 167 to 226.

There has been no lack of attempts in the past to prepare polyolefin-containing plastics which are degraded under the action of light or under the conditions of composting.

2 -2- German Offenlegungsschrift 2,136,704 describes thermoplastic compositions whose degradability results from the addition of a non-ionic complex, in particular containing sulfur,of a metal of atomic number 22 to 29, 40 to 47 or 57 to 79.

German Offer-±egungsschrift 2,616,257 concerns photodegradable polymer compositions which contain at least one polymer and at least one iron(II) salt. The iron is added in the form of a carboxylic acid salt having an alkyl chain of at least 6 carbon atoms, the alkyl chain containing a further functional group in the 4- S* or 5-position. Polymers which can be added are polyethylene, polystyrene and various comonomers based on ethylene or styrene.

00o 15 German Offenlegungsschrift 2,316,697 relates to a polymer substance which is photodegradable by the action of ultra-violet irradiation and comprises a customary ethylene homopolymer or ethylene copolymer and an ethylene/carbon monoxide copolymer, this mixture contain- S 20 ing 0.1 to about 15% by weight, relative to the total po] mer substance, of carbonyl groups produced by copolymerization of carbon monoxide, The known degradable polymer mixtures are either limited to the use of very particular plastics or tied to the 25 addition of specific metal compounds which are difficult to obtain. In addition, the degradation behavior of thse substances frequently proves to be in need of improvement.

There was therefore a demand for degradable polymer mixtures which, firstly, in general incorporate polyolefins prepared by low-pressure synthesis and thus utilize the properties which distinguish these polymers, secondly are readily accessible, and thirdly have good i degradability.

2a The present invention therefore provides a photodegradable polymer mixture comprising a polyolefin prepared by low-pressure synthesis, and a copolymer containing ethylene, carbon monoxide and, if appropriate, further polymerizable components, in such an amount that the polymer mixture r itains 0.5 to 5% by weight of carbon monoxide, and 10 to 150 ppm of a carboxylic acid salt of an element of atomic number 24 to 30 and cerium. Preferably the polymer mixture comprises 75 to 95% by weight of the polyolefin and 5 to 25% by weight of the copolymer containing carbon monoxide. Preferably the polyolefin is high-density polyethylene,. polypropylene, polybutene, polyisobutylene or poly(4-methyl-1-pentene). Preferably the copolymer 1 0 containing carbon monoxide comprises 60 to 96 parts by weight of ethylene, 5 to parts by weight of carbon monoxide and, if appropriate, 1 to 18 parts by weight or a further monomer. Preferably the salt is a salt of cerium, iron or cobalt with iron being particularly preferred.

The invention also includes a process for the preparation of a polymer mixture as 15 above which comprises mixing and warming the polyolefin, the copolymer containing S carbon monoxide, and the carboxylic acid salt to melt the mixture and optionally extruding the mixture.

Further preferred features of the invention will be evident from the following description of particularly preferred embodiments of the invention.

0j 3 abzvcmentioned-dia photodegradable polymer mixtures comprising (a pa lyolefin prepared by low-pressure synthegs and a copolymer containing ethylene, c n monoxide and, if appropriate, further polyme able components, in such an amount that the poy r mixture contains 0.5 to 5% by weight of c rn .onoxide, and 10 to 150 ppm of a carbo ic acid salt of an element of atomic number 22 to The polymer mixtures according to the invention have the following advantages. Firstly, they generally extend to polyolefins prepared by low-pressure synthesis. Secondly, 0: they are readily accessible since they comprise customary components which are available in industrial quantities 15 which merely have to be mixed with one another and So processed, if necessary. In addition, they cover a very broad field of application, since their degradability can be affected both via the carbon monoxide content and via the amount of carboxylic acid salt added. This in turn 20 means that it is possible to vary the polyolefin copolymer containing carbon monoxide ratio to a relas* s tively great extent. This makes it possible to maintain a certain degradability while varying the other properties, such as toughness, tear strength, transparency, elongation behavior or sheeting-out ability. Conversely, there is no problem, for example, in prespecifying a certain toughness or tear strength and adjusting the degradability as desired.

Thirdly, the polymer mixtures according to the invention are distinguished by improved degradability, since, surprisingly, the carbon monoxide content and the carboxylic acid salt content do not have an additive effect with respect to the degradation behavior, but instead achieve a synergistic effect extending beyond the action 35 of the individual components.

The degradable polymer mixtures comprise 75 to 95% by i 4 weight of the polyolefin and 5 to 25% by weight of the copolymer containing carbon monoxide.

Polyolefins are taken to mean products of the polymerization of alkenes, in particular high-density polyethylene, polypropylene, polybutene, polyisobutene and poly(4methyl-1-pentene), but also polycycloolefins which polymerize with a ring opening to form polyolefins (cf.

Calderon, Rev. Macromol. Chem. 8 (1972), 105 to 109).

Highly suitable polyolefins are high-density polyethy- 10 lenes, polypropylene and polyisobutene, in particular high-density polyethylenes and polypropylene.

o e oo 15 *e 20 25 The preparation (low-pressure synthesis) of these polyolefins is carried out by reacting the monomer or monomer mixtures at 0.1 to 4.0 MPa and 20 to 100 0 C, usually in the presence of catalysts which comprise an organometallic compound of an element from group 3 of the Periodic Table of the Elements, and a titanium compound (so-called Ziegler or Ziegler-Natta catalysts). (cf. Ullmanns EncyklopAdie der techn. Chemie [Ullmann's Encyclopedia of Industrial Chemistry), Verlag Chemie, Weinheim-Basel, 1980, Volume 19, pages 183 to 185, 198 to 202, 211 to 212 and 219 to 220).

The low-pressure polymerization (low-pressure synthesis) is carried out at a pressure of from 0.1 to 4.0, in particular 0.2 to 2.0, preferably 0.5 to 1.0, MPa. The polymerization temperature is 20 to 100, in particular to 95, preferably 60 to The copolymer containing ethylene, carbon monoxide and, if appropriate further polymerizable components comprises 60 to 96, in particular 65 to 92, preferably 70 to parts by weight of ethylene, 5 to 20, in particular 7 to preferably 8 to 14, parts by weight of CO and, if appropriate, 1 to 18, in particular 2 to 15, preferably 3 to 12, parts by weight of a further monomer. Further ij 5 monomers which may be mentioned are vinyl esters, vinyl ethers and esters of acrylic acid or methacrylic acid and an aliphatic C 1 to C.-alcohol. Vinyl acetate, methyl acrylate, ethyl acrylate and butyl acrylate are particularly suitable.

This copolymer is prepared by reacting the monomer or monomer mixtures at 50 to 350 MPa and 100 to 350 0 C in the presence of oxygen or compounds which form free radicals (so-called high-pressure synthesis). To this end, a mixture comprising ethylene, CO and, if appropriate, a further monomer is polymerized.

S* Se o Sb..

S

0, 2

S.

a

S

15 *S 20 The polymerization is carried out under a pressure of from 50 to 350, in particular 100 to 300, preferably 125 to 275 MPa. The polymerization temperature is 100 to 350°C, in particular 120 to 325, preferably 130 to 300°C.

The polymerization initiators employed arr oxygen or compounds which forin free radicals. The compounds which form free radicals include organic peroxides, hydroperoxides or azo compounds. Peroxides from the classes comprising the diacyl peroxides, pero' 1 'carbonates, alkyl peresters, perketals, dialkyl pe-: s, ketone peroxides and alkyl hydroperoxides nave proven successful.

5S5 *5 0

(IS

The compounds which form free radicals may be used alone 25 or in mixtures. The polymerization initiators are employed in a concentration of from 3 to 50, preferably to 40, in particular 10 to 25, ppm by weight, relative to ethylene. They are fed to the polymerization directly or as a solution in an organic solvent. The solvents used are hydrocarbons, such as isooctane, benzene, toluene or petroleum ether fractions. The residence time of the monomer mixture in the polymerization step is 30 to 1PO, in particular 50 to 160 and preferably 60 to 140 seconds.

The reaction can take place in the high-pressure reactors 6 known for the polymerization of ethylene and ethylenecontaining monomer mixtures. These include stirred autoclaves and tubular reactors (cf. Ullmanns Encyklopadie der technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], 4th Edition, Verlag Chemie, Weinheim-Basel, 1980, Volume 19, pages 169 and 172 to 175). If a tubular reactor is used, the entire monomer mixture already containing initiators can be fed to the reactor in one stream. However, it is particularly advantageous to use a tubular reactor with subsequent cold-gas and initiator feed and to divide the monomer mixture into at least two sub-streams. In this case, one Ssub-stream is fed to the reactor input, and further substreams are fed to the reaction zone along the reactor, 15 usually in the region of a peak temperature.

o o The copolymers can be prepared by polymerization of the appropriate monomer mixtures under the reaction conditions already mentioned above. Their synthesis is also described in German Auslegeschrift 2,301,889.

20 The copolymer containing carbon monoxide is employed in such an amount that the polymer mixture according to the invention contains 0.5 to 5, in particular 0.7 to S preferably 1.0 to 3.0, by weight of carbon monoxide (in copolymerized form).

25 The polymer mixture contains, as the third component, to 150, in particular 15 to 120, preferably 20 to 100 ppm of a carboxylic acid salt of an element of atomic number c o 30 cknck eer^-W.r%.

Carboxylic acid salts of cerium, vanadium, chromium, manganese, iron, cobalt, nickel and copper are highly suitable, and the carboxylic acid salts of cerium, iron and cobalt have proven particularly successful. In many cases, carboxylic acid salt. of iron or of cobalt, in particular of iron, have proven particularly suitable.

It is possible to use salts of aliphatic, cycloaliphatic,

|I

7 araliphatic and/or aromatic carboxylic acids, in particular aliphatic carboxylic acids having 4 to 14 carbon atoms.

The salts of aliphatic carboxylic acids include salts of monocarboxylic acids and dicarboxylic acids having 4 to 14 carbon atoms, in particular salts of 2-ethylhexanoic acid, isononanoic acid .pared by hydroformylation of diisobutylene and subsequent oxidation of the hydroformylation product), isotridecanoic acid (prepared by hydroformylation of tetrapropylene and subsequent oxidation of the hydroformylation product), adi ic acid, *s a* S maleic acid, fumaric acid and itaconic acid, but salts of ee,' 2-ethylhexanoic acid should be particularly emphasized.

However, salts of aromatic carboxylic acids, such as benzoic acid, salicylic acid, phthalic acid and a- and -naphthoic acid, can also be used.

The polymer mixtures are prepared by mixing and warming the individual components, namely the polyolefin, the copolymer containing carbon monoxide and the carboxylic 2 0 acid salt, to melting and optionally extruding the mixture. Commeirial extruders, such as twin-screw extruders, can be used for the extrusion.

Due to their particular properties the transparency, rigidity, gloss, toughness and tear strength should be 25 mentioned the polymer mixtures should preferably be used as film materials.

The examples described below an the experimental part support the present invention, without representing a limitation.

Experimental part Preparation of the degradable polymer mixtures The individual components used are the polyolefin (a)

I

*i I 1 iiiii 11 *owHa 8 prepared by low-pressure synthesis, the copolymer (b) containing ethylene, carbon monoxide and, if appropriate, further polymerizable components, and carboxylic acid salt The individual components are mixed in such a ratio that the desired CO content is achieved in the polymer mixture, the mixture is heated to a temperature of about 130 to 160 0 C, which is above the melting range, and extruded.

The samples intended for the irradiation experiment already have the shape necessary for determining the residual tensile impact strength.

9S e6 Irradiation experiment The effect of the action of light on the degradation behavior of the samples is determined using a rapid- 15 irradiation bench instrument (original name: Hanau Suntest; commercial product from Heraeus). The irradiation strength is 820 W/m 2 in the wavelength range between 300 and 800 nm (global radiation). Th illumination strength is about 150 kLux. The radiation is lim.ted at 20 280 nm (1 nm 10 9 m).

The reduction in the tensile impact strength, which is determined by a standardized method (DIN 53 448), is used as a measure of the degradability of the sample to be investigated. The samples are regarded as sufficiently 25 degraded as soon as the tensile impact strength has dropped to a residual value 50% of the original tensile impact strength. The irradiation duration necessary to accomplish this is the embrittlement time.

The results achieved are summarized in the table below.

Examples A and B are comparison experiments, while Examples 1 to 7 relate to polymer mixtures accoiding to the invention. The individual components, namely the polyolefin and (a 2 the copolymer (b 2 and (b 3 and the carboxylic acid salt (c 1

(C

2 (c 3 and -9-

(C

4 are listed under starting material The polymer mixtures -investigated are characterized by specification of the carbon monoxide content and the carboxylic i salt content and of the embrittlement time.

*ad bobs 0* 140 46 It i.

Table I ~9O 4 4 4 1 d 9

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90 9 9 S 9 4 4 9 59 4 4 4~ 494 9# S 949 490 9 9 999 49.9 9 9* 9 9 9 9 9 9 9 4 5 Ob 9 994 II 999 9 9 9 1 S 154 3U Polymer mixture t Example Starting material CO content Carboxylic acid salt Embrittlement time by weight) 1 (ppm) jhvs 1.25 1.25 100 100 504 48 96 B a 2 672 3 a 2 b 2 c, 0.8 100 168 4 a 2 b 2 c 1.6 100 96 b 2 C,2.3 100 6a 2 b 3 c 3 2.0 100 72 7 a 2 b 3 c 4 2.0 100 a, polypropylene homopolymer, MFI (190/5) =2 g/10 min, d 0.903; commercial product from Hoechst AG: name Hostalen PPK 1060 F a 2 polyethylene homopolymer, MFI (190/5) 0.40 /10 min d 0.943; commercial product from Hoechst AG: name Hostalena GX 5050 ethylene/carbon monoxide copol~ymer containing 13.8% by weight of CO, MFl (190/2.16) g/10 min b 2 ethylene/carbon monoxide copolymer containing 18% by weight of CO, MFl (190/2.16) g/10 min b 3 ethylene/carbon monoxide copolymer contaj,7'n-g 16% by weight of CO, MFl (190/2.16) 3.3 g/10 min Fe 2-athylhexanoate; c 2 =Ce 2-ethy-exnae

C

3 Co isononanoate; C 4 =Fe isononanoate -4

Claims

4. 0 0* *0r Io 00 0 *o 0 4 0* 0* 0 C *0*0 11 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A photodegradable polymer mixture comprising a polyolefin prepared by low- pressure synthesis, and a copolymer containing ethylene, carbon monoxide and, if appropriate, further polymerizable components, in such an amount that the polymer mixture contains 0.5 to 5% by weight of carbon monoxide, and 10 to 150 ppm of a carboxylic acid salt of an element of atomic number 24 to 30 and cerium. 2. A polymer mixture as claimed in claim 1, which comprises 7J to 95% by weight of the polyolefin and 5 to 25% by weight of the copolymer containing carbon monoxide. 3. A polymer mixture as claimed in either of claims 1 and 2, wherein the polyolefin is high-density polyethylene, polypropylene, polybutene, polyisobutylene or poly(4- methyl-1-pentene). 4. A polymer :mixture as claimed in one or more of claims 1 to 3, wherein the copolymer containing carbon monoxide comprises 60 to 96 parts by weight of ethylene, 5 to 20 parts by weight of carbor; monoxide and, if appropriate, 1 to 18 parts by weight of a further monomer. A polymer mixture as claimed in one or more of claims 1 to 4, wh!ch contains a caiboxylic acid salt of cerium, iron or cobalt.
6. A polymer mixture as claimed in one or more of claims 1 io 4, which contains a carboxylic acid salt of iron.
7. A process for the preparation of a polymer mixture comprising a polyolefin prepared by lcw-pressure synthesis, and a copolymer containing ethylene, carbon monoxide and, if appropriate, further polymerizable components, in such an amount that the polymer mixture contains 0.5 to 5% by weight of carbon monoxide, and 10 to 150 ppm of a carboxylic acid sn!i of an element of atomic number 24 to 30 and cerium v'nich process comprises mixing and warming the polyolefin, the copolymer containing carbon monoxide, knd the carboxyllc acid salt to melt the mixture and optionally extruding the mixture. ~1 L. 12 Gf A process as claimed in claim 7 in which there is added from 75 to 95% by weight of the polyolofin and 5 to 25% by weight of the copolymer containing carbon monoxide.
9. A process as claimed in claim 7 or 8 wherein the polyolefin is high-density polyethylene, polypropylene, polybutene, polylsobutylene or poly(4-methyl-1- pentene). A process as claimed in claim 7, 8 or 9 wherein te copolymer containing carbon monoxide comprises 60 to 96 parts by weight of ethylene, 5 to 20 parts by weight of carbon monoxide and, *1 appropriate, 1 to 18 parts by weight of a further monomer.
11. A process as claimed in any one of claims 7 to 10 which contains a carboxylic acid salt or cerium, iron or cobalt. S 12. A process as claimed in claim 11 in which the salt is of iron.
13. The use of a polymer mixture as claimed in any one of claims 1 to 6 as a film material. DATED this 28th day of April, 1992. HOECHST AKTIENGESELLSCHAFT WATERMARK PATENT TRADEMARK ATTORNEYS THE ATRIUM 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRAUA DBM:;AS-JZ ^v 0i52