IL43336A - Polymeric composition having controllable degradation rate in sunlight and air - Google Patents

Description

43336/2 POLYMERIC COMPOSITION HAVING CONTROLLABLE DEGRADATION RATE IN SUNLIGHT AND AIR DEGRADABLE HYDROCARBON POLYMERS r- ABSTRACT OF THE DISCLOSURE A degradable composition is made from a polymer of a mono olefin having 2-3 carbon atoms or styrene and an additive comprising (1) a derivative of an organic compound of a metal which has at least two valence states and (2) a benzoyl derivative of an organic compound or a triazole.

DEGRADABLE HYDROCARBON POLYMERS This invention relates to a new polymer composition based on polystyrene, polypropylene, polyethylene or ethylene-propylene copolymer and a novel additive system, which has predictable degradability when exposed to sunlight and air.

It is known that unstabilized polymers of propylene, styrene and ethylene will slowly degrade outdoors in presence of air and sunlight. Furthermore, it is known that certain additives will enhance this degradation, e.g. see Newland U.S. patent 3,592,792, Moor U.S. patent 3,320,695 and Newland U.S. patent 3,454,510. None of these additives, however, have proved to be satisfactory because the rate of degradation is still much too slow to cause the polymer to degrade within a reasonable length of time or the cost is too high to be economically feasible.

It is extremely important today to find an effective means of destroying plastic materials, which are used in packaging and agricultural mulch films. The pollution problem is becoming more severe as used plastic bottles, con-tainers, wrapping film, sheet, etc., accumulate in garbage dumps, along shores, in rivers and other places. There is a great need for some sort of degrading system that will allow the plastic to have a useful life, after which the plastic will degrade into a material that can be handled easily.

This invention provides a new polymeric system^^ capable of degrading to a crumbly friable mass in a matter of hours when exposed to sunlight and air. The rate of degradation can be controlled such that the degradation in sun-light and air can be made to happen at any time from a few hours to a few months. This can be done primarily by controlling the amount of additive system incorporated in the polymer and by the method of incorporation.

In the course of our study on additives to bring about degradation of polymers, two types of additives were combined. An unexpected synergism resulted giving amazingly fast degradation rates. Although the precise mechanism is not known, it appears highly probable that the two components of the additive system degrade the polymer by differ-ent mechanisms and that the breakdown products produced by the effect of one component becomes very vulnerable for attack by the second component.

As the polymer there is employed a polymer of a mono olefin having 2- to 3 carbon atoms, i.e., polyethylene, polypropylene, ethylene-propylene copolymer (e.g., ethylene and propylene in a mole ratio of 5:95, 25:75, 50:50, 75:25 or 95:5) , . or polystyrene .

Any of the conventional polyethylenes . can be used, i.e., low, medium or high density, e.g., density of 0.914 to 0.96, for example polyethylene having a density of 0.918 -2- and a melt index of 1.7, polyethylene of density 0.945, '%oly ethylene of density 0.925, or polypropylene having a bire- ! firingent melting point of about 168 °C. and a reduced speci- j fic viscosity of 2.5 (measured on a 0.1% solution in decahy- I dronaphthalene at 135 °C). j Typical examples of polyethylene, polypropylene, ethylenepropylene copolymers and polystyrene are set forth in the Encyclopedia of Polymer Science and Technology, Vol. 6j, pages 275-386, Vol. 11, pages 597-619 and Vol. 13, pages 156-439, the entire disclosure of which are hereby incorpo- ! rated by reference.

I ! The additive system is composed of two components i wh I ich we will call P and S for convenience. i P is a metallic derivative, derived from a transi- trimethylacetic acid, pelargonic acid, decanoic acid, lauric i acid, palmitic acid, stearic acid, eicosanic acid, oleic \ ■ -3- acid, linoleic acid, palmitoleic acid, acrylic acid, gi ^-\. colic acid, lactic acid, citric acid, tartaric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, suberic acid, sebacic acid, tricarbyllic acid, fluoroacetic acid, chloroacetic acid, bromoacetic acid, dichloroacetic acid, alpha-chloropropionic acid, beta- chloropropionic acid, saccharic acid, phenylacetic acid, benzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, o-chlorobenzoic acid, m-bromobenzoic acid, terephthalic acid, phthalic acid, neodecanoic acid.

Examples of such salts include zirconium IV neo- decanoate, zirconium II neodecanoate, zirconium IV oxalate, , triglycolatozirconylic acid, zirconyl acetate, trilactozir- conylic acid, zirconium IV stearate, zirconium IV octoate, zirconium IV palmitate, zirconium IV oleate, stannous acetate, stannic acetate, stannous neodecanoate, stannous formate, stannous stearate, stannous oxalate, titanium oxalate, titanium IV neodecanoate, titanium IV stearate, stannous 2- ethylhexoate , nickelous acetate, nickelous formate, nickel II naphthenate, nickel II oleate, nickel II stearate, nickel II oxalate, nickel II formate, nickel II acetate, manganous acetate, manganous lactate, manganous oxalate, manganous tartrate, manganous benzoate, manganic acetate, ferrous acetate, ferric acetate, ferrous formate, ferric formate, fer- rous lactate, ferric lactate, ferric malate, ferric oleate, -4- ferrous oxalate, ferric oxalate, ferrous citrate, ferri^p^ citrate, ferric benzoate, antimony lactate, cupric lactate, cupric acetate, cupric oleate, cupric stearate, cupric naph-'thenate, cupric formate, cobalt II oleate, cobalt II stear-ate, cobalt II naphthenate, cupric oxalate, cupric tartrate, cobaltous tartrate, cobaltous linoleate, cobaltous palmi-tate, cobaltous oxalate, cobaltous acetate, cobaltic acetate, manganous naphthenate, iron naphthenate, manganous oleate, manganous linoleate, cobaltous octoate, manganous octoate, iron resinate, cobaltous resinate, manganous resinate, manganous neodecanoate , cobalt II neodecanoate, chromic oleate, stannic oleate, chromous acetate, chromic acetate, chromic stearate, chromic naphthenate, cupric adipate, litanium IV adipate, and litanium IV phthalate.

There also can be formed complexes or chelates of the same metals with beta diketones such as 2 , 4-pentanedi-one (acetylacetone) . Examples of such 2 , 4-pentanedione chelates include cobaltic pentanedione, ferrous pentanedione, ferric pentanedione, cupric pentanedione, titanium IV pentanedione, zirconium IV pentanedione, stannous pentanedione, nickel II pentanedione, chromium III pentanedione, manganous pentanedione .

S is a benzoyl derivative, preferably having a ketone group or a benzotriazole derivative and is represented by the following structures: where R-^ through R5 are H, halogen, alkyl, aryl, alkoxy, or aryloxy and Rg may be alkyl, aralkyl, aryl, aroyl or pyri-dyl group (unsubstituted or having halogen, alkyl, aryl, alkoxy or aryloxy substituents) and where R^^ through R-^ may be H, halogen, alkyl, aryl, alkoxy, aralkyl, aroyl or aryloxy group. In Ri - R6 and Rn - R14 the alkyl groups can have 1 to 20 carbon atoms as can the alkoxy groups.

Examples of benzoyl compounds are benzophenone, 4-chlorobenzophenone, 4,4 ' -dimethoxybenzophenone, 4-fluoro-benzophenone, 2 -phenyl acetophenone , o-dibenzoyl benzene, 4-bromobenzophenone, 2,4,5-triethoxybenzophenone, 2,4,6-trimethoxy benzophenone, 4-methoxybenzophenone, 4-bromo-4'-chlorobenzophenone, 4-methylbenzophenone , 4 , 4 ' -dichloro-benzophenone, phenyl benzoate, benzil, acetophenone, 4'-chloroacetophenone, 4-chlorobutyrophenone, propiophenone, butyrophenone , 2-chloroacetophenone , 3-chloroacetophenone, 2 , 4, 6-trichloroacetophenone, 2-methylbenzophenone, benzophenone, 4-eicosanylbenzophenone , 4-octadecylbenzo-phenone , 4,4" -dioctadecylbenzophenone , 4-ethoxybenzophenone, 4-octadecoxybenzophenone, 4-eicosanoxybenzophenone , 4-butoxybenzophenone, 4,4' -dioctadecoxybenzophenone , 4,3'-diethoxybenzophenone , benzyl phenyl ketone, 2-phenylbenzo-phenone, 4-phenylbenzophenone , 2-pyridyl phenyl ketone, pyridyl 4-chlorophenyl ketone, 2-chloro-4-methyl benzo-phenone, 3-benzoyl acetophenone , chloromethyl phenyl ketone, 4 , 4 ' -dimethylbenzophenone , 4,4 ' -diphenoxy benzophenone, 3-phenoxybenzophenone, phenyl 1-naphthyl ketone, 2 ' -acetonaph-tone and 1 ' -acetonaphthone, phenyl 4-chlorobenzoate, phenyl 3-methylbenzoate, phenyl 4-dodecylbenzoate, phenyl 2-bromo-benzoate, phenyl 3-fluorobenzoate, phenyl 2 , 4-dimethylbenzo-ate, phenyl 2-methyl-4-bromobenzoate, phenyl 2 , 4 , 5-trichloro-benzoate, phenyl 2-methoxybenzoate, phenyl 4-butoxybenzoate, phenyl 4-phenoxybenzoate , methyl benzoate, ethyl benzoate, sec. butyl benzoate, octadecyl benzoate, eicosanyl benzoate, 4-chlorophenyl benzoate, 3-methylphenyl benzoate, 4-octyl-phenyl benzoate, 4-octadecylphenyl 4 ' -chlorobenzoate , 4-methoxyphenyl benzoate .

Examples of benzotriazole derivatives include ben-zotriazole, 5-chlorobenzotriazole, 5-bromobenzotriazole, 5-fluorobenzotriazole, 5-methylbenzotriazole , 5 , 7-dimethyl-benzotriazole, 5-methoxybenzotriazole, 5-ethoxybenzotria- zole, 5-octadecoxybenzotriazole , 5-octadecylbenzotriazo-^£?. 5-methyl-7-chlorobenzotriazole , 6-methylbenzotriazole, 5,6-dimethyl-8-chlorobenzotriazole, 5-benzylbenzotriazole, 7-phenoxybenzotriazole, 5-benzoyl benzotriazole .

Different methods of incorporation of the additives have been used effectively. In relatively thin plastic forms such as sheets and films the additive may be incorporated by merely dipping the plastic into a solution of the additive for a short time (e.g. a few seconds). For thicker plastic parts the additive can be incorporated effectively by normal processing techniques similar to the way other additives such as fillers are incorporated. This may be done on a roll mill, Banbury or extruder effectively.

This latter method is preferred even for film and bottles because of uniformity and control of level of additive in-^ corporated.

A special method that has many practical uses is a spray-on technique. This is useful' on trash heaps where large quantities of used plastic articles have accumulated. Rather than burning the plastic, it could be sprayed on easily and quickly with a solution of the additives in any volatile solvent and in a few days the useless plastic will have virtually disappeared. This can solve a major pollution problem.

Based on the total of the polymer and the additives the polymer is normally 90 - 99.999% and the additive is^ 0.001 - 10% usually being present in an amount of at least 0.01%. The P and S components of the additive can be present in equal amounts or either one can be excess, e.g. the additive can be 5 to 95% P and 95 to 5% S . Usually it is preferred to have the S component as the larger component.. As is shown in example 1 as little as 0.1 ppm of additive is effective in disintegrating the polymer.

Unless otherwise indicated all parts and percent-ages are by weight.

The compositions of the present invention degrade very rapidly under a sunlamp but do not degrade rapidly under a regular fluorescent lamp. The compositions degrade under the influence of ultra violet light more rapidly than when the polymer is present with no additive or with only one additive.

Direct incorporation of the additives into the polymer by compounding on a roll mill or through a compounding extruder gives exact levels of the additives. In the dip technique the amount of each additive incorporated in the specimen (film or sheet) was determined by subjecting the- specimen to analysis.

A 1-1/2 mil polyethylene film was dipped for 10 seconds in the following solution at 60 °C : 50 g. CHC13 -9- 2g. Zirconium II Neodecanoate 2g. 4-Chlorobenzophenone After dipping the film was dried and analyzed. The following analyses were reported: Zr 0.1% CI 0.045% This corresponds to the following percentages of the original additives: Zr Neodecanoate 0.43% 4-Chlorobenzophenone 0.085% Thus only very small amounts are needed to be effective.

The controllability and predictability of the degradation of the polymer composition can be important. In the case of agricultural mulch films, exposure times to degra-dation must be precise so that new growing plants under the film can break through the film at the right time and thus assure strong healthy growth for the plants. In other areas, such as plastic bottles, the precision of the time for degradation may not be so critical. Still, within lim-its, some degree of accuracy is desirable. Our studies have allowed us to correlate light exposure time to degradation with amount and type of additives used. These studies have involved both sunlamp continuous exposure as well as outdoor sunlight exposure. In the sunlamp exposures the sunlamp was run 24 hours a day. -10- Samples of film (1 to 5 mils) and sheet mils) were exposed by mounting a 1' x 3' specimen in clamps on a holder so that it was suspended about 1/4" above the surface. Each specimen thus mounted was placed on an 18" diameter horizontal round table, which was rotated at 33 rpm. Above the table at approximately JUL inches were 4 General Electric RS sunlamps. All of this equipment was housed in a metal box approximately 21" wide, 21" deep and 24" high. On opposite sides of the boxes at the turntable level were two openings 17" wide by 7" high. A fan of adjustable speed was used to blow through the openings to con trol the turntable temperature (37° ± 2 °C . ) .

The light intensity was checked periodically to make sure that it remained fairly constant. When a drop in intensity was observed, new sunlamps were used to replace the used lamps.

The specimens were periodically tested by applying pressure on the suspended film or sheet. A specimen was considered to have failed when it broke on application of a slight pressure (zero elongation) .

The sunlamp exposures were also correlated with tests in outdoor sunlight.

During the months from April through September an outdoor rack was used to expose samples of polymer film and sheet. These samples were mounted in holders similar to -11- those used for sunlamp exposure as previously described.^ The rack faced South and was set at a 45° angle to the hor izontal. Although outdoor sunlight intensity is variable depending on haze, clouds and rain, over a period of time reasonably good correlation was obtained as shown by typical examples in the following Table: Table 1 TIME TO FAILURE (DAYS) The examples that follow are submitted to illustrate and not to limit this invention.

EXAMPLE 1 Commercial crystal grade polystyrene was compound ed with the following ingredients on a roll mill to give mixtures with different levels of additive: 1 part of Zirconium Neodecanoate 5 parts of o-Dibenzoyl Benzene For each level of additive mixture a compounded specimen was produced, pressed into a 2 mil film and exposed under sunlamps on a revolving table. The film specimens were tested periodically. When a film broke under slight pres- ■12- sure (essentially zero elongation) , this was taken as time of failure.

The results are set forth in Figure 1 of the draw-' ings which is a graph showing concentration of total addi- tive mixture in parts per million against days to break of the polystyrene film.

Polypropylene and polyvinyl chloride showed a similar effect; however, the effect varies somewhat from polymer to polymer as well as due to interaction between each poly- mer and a specific degrading system. But in general the pattern is the same as shown in Figure 1.

EXAMPLE 2 Commercial polypropylene film specimens (1" x 3" x .0015") were dipped in the following chloroform solutions at 60°C. for 2 seconds, washed in fresh chloroform for 2 seconds and dried at room temperature.

Soln. 1: Ferrous Pentanedione (2%) Soln. 2: 4-Methyl Benzophenone (2%) Soln. 3: A 1 to 5 mixture of Solns . 1 and 2 (i.e. a mixture of 10 ml of solution 1 with 50 ml of solution 2 was used) The treated polypropylene film specimens were mounted in film holders and exposed to 4 GE sunlamps on a revolving table. The film specimens were tested periodically.

When a film broke under slight pressure, this was taken as -13- the time of failure. For the described specimens the lowing results were obtained: Dip Soln Hours to Failure Soln 1 210 Soln 2 160 Soln 3 Less than 16 Examples 3 and 4 also show the synergistic effect Except for the additives, treatment of the film was the same as described in Example 2 using a chloroform' solution of the additives.

FILM EXAMPLE USED COMPONENTS HOURS TO FAILURE 3 1-1/2 mil Titanium (+ 4) 200 hours polystyrene pentanedione ' 4-Ethoxybenzo- 185 hours phenone 1-5 ratio of 16 hours above components 4 1-1/4 mil Co Pentanedione 114 hours * polypropylene 4-Bromobenzo- 170 hours phenone 1-5 ratio of <16 hours above components In the following examples the chloroform solution contained equal parts ~of components A and B: -14- . .

Polyethylene Film TIM 10 sec. dip in CHCl, Soln.

Com EXAMPLE COMPONENT A COMPONENT B A Zirconium II 4-Chlorobenzo- Neodecanoate phenone Cobalt + 2 4-Chlorobenzo- Neodecanoate phenone Ferric 4-Chlorobenzo- Pentanedione phenone 8 Ti +4 2 -Phenylaceto- Pentanedione phenone Ferrous 2 -Phenylacetc- Pentanedione phenone 10 Cobalt III 4-Chlorobenzo- Pentanedione phenone 11 Cobalt III 2-Phenylaceto- Pentanedione phenone 12 Zirconium +2 2-Phenylaceto Neodecanoate 13 Ferrous 4-Chlorobenzo- Pentanedione phenone 14 Titanium IV 4-Chlorobenzo- Pentanedione phenone 15 Titanium IV 2-Phenylaceto- Pentanedione phenone 16 Ferrous Benzophenone Pentanedione 17 Ferrous 4-Methylbenzo- 10 Pentanedione phenone 18 Ferrous 4-Bromobenzo- Pentanedione phenone 19 Ferrous 4-Fluorobenzo- Pentanedione phenone 15 20 Ferrous 4,4 ' -Dichloro- Pentanedione benzophenone 21 Ferrous Phenyl Benzoate Pentanedione 22 Ferrous 2 ,4,5-Triethoxy- 20 Pentanedione benzoph°enone Ferrous 2,4, 6-Trimethoxy Pentanedione benzophenone Ferrous 4-Methoxybenzo-Pentanedione phenone Ferrous 5 -Chlorobenzo-Pentanedione triazole Ferrous Acetophenone Pentanedione Ferric 4-Chlorobenzo-Napthenate phenone Ferrous 4 ' -Chloroaceto-Pentanedione phenone Ferrous Stearate Benzophenone Ferrous Octoate 4-Chlorobenzo- phenone Ferrous 4-Chlorobenzo-Neodecanoate phenone Ferrous o-Dibenzoyl-Pentanedione benzene Ferrous 2 ' -Acetonaphthone 281 Pentanedione Ferrous 11 -Acetonaphthone · 281 Pentanedione Ferrous Benzil 281 Pentanedione Ferrous Phenyl 2-Pyridyl Ketone 281 Pentanedione

Claims (28)

1. A polymeric composition having a controllable degradation rate in sunlight and air comprising (1) a polymer which is a member of the group consisting of polymer of an olefin having 2 to 3 carbon atoms and styrene polymers and (2 ) a two component additive system, the first component of said additive being selected from the group consisting of I {/el) salts of an organic carboxylic acid with a metal capable of existing in at least two valence states and b^ chelates of a metal capable of existing in at least two valence states with a beta diketone, and the second component of the additive being selected , from the group consisting of (a-)- a benzoyl comp and wher the group con sisting of hydrogen, halogen, alkyl, alkoxy, aryloxy and aryl, and Rg is selected from the group consisting of alkyl, aralkyl, aryl, aroyl, and pyridyl groups and such groups substituted with a substituent from the group consisting of halogen, alkyl, aryl, alkoxy, and aryloxy and R^, R12, and R^ are selected from'' the group consisting of hydrogen, alkyl, aryl, alkoxy, aralkyl, aroyl and aryloxy groups, said additive system being 43336-2 said components of the additive system being present in an amount sufficient that the mixture thereof is more effective to decrease the time; of degradation of the polymer than a corresponding amount: of either member of the two component additive system by itself.

2. A polymer composition according to claim 1 wherein the metal of the first component, is: selelcted from the group consisting of iron, cobalt, nickel, chromium, titanium, vanadium, manganese, copper, zirconium and tin and when the first component is a chelate of a beta diketone the diketone is 2 ,4-pentanedione .

3. A polymeric composition according to claim 2 wherein the first component of the additive system is t/df)/ I Ί.

4. A polymeric composition according to claim 3 wherein the second component of the additive- system is /(/.}/. II

5. A polymeric composition according to claim 4 wherein the organic carboxylic acid is free of non-hydrocarbon substituents .

6. A polymeric composition according to claim 5 wherein at least two of R-^, R2 R3, R4 and R5 are hydrogen and the rest are selected from the group consisting of hydrogen, lower alkyl, halogen, lower alkoxy, benzoyl and phenyl and Rg is selected from the group consisting of lower alkyl, phenyl, halophenyl and phenoxy.

7. A polymeric composition according to claim 6 wherein the second component of the additive is a ketone.

8. A polymeric composition according to claim 2 wherein the first component of the system is £}->)·.I

9. A polymeric composition according to claim 8 wherein the second component of the additive system is ½3.jj<

10. A polymeric composition according to claim 9 wherein at least two of R^, R2# R3, R4 and R5 are hydrogen and the rest are selected from the group consisting of hydrogen, lower alkyl, halogen, lower alkoxy, benzoyl and phenyl and Rg is selected from the group consisting of lower alkyl, phenyl, halophenyl and phenoxy.

11. A polymeric composition according to claim 10 wherein the second component of the. additive, is a. ketone.

12. A composition according to claim 1 wherein^ the two component additive system is present in an amount of at least 1 ppm of the polymer.

13. A composition according to claim 12 wherein each component of the additive system is present in an amount of 5 to 95% of the additive system.

14. A composition comprising a first component I selected from the group consisting of i-ar) salts of an organ¬ ic carboxylic acid with a metal capable of existing in at least two valence states and chelates of a metal capable of existing in at least two valence states with a beta di- ketone, arid a second component selected from the group con- sisting of -(-a-) a benzoyl compound, of the formula and /&) a benzotriazole of the formula: where R^, R2, R3, R4, R5 and Rg are selected from the group consisting of hydrogen, halogen, alkyl, aralkyl, alkoxy, aryl, aroyl and pyridyl groups and such groups which are un- sisting of halogen, alkyl, aryl, alkoxy, aralkyl, aroyl and aryloxy and R^, ¾2' R13 anc^ R14 are selected from the group consisting of hydrogen, alkyl, aryl, alkoxy, aralkyl, aroyl and aryloxy groups, each of said components being present in an amount sufficient that the mixture thereof is more effective to decrease the time of degradation of a polymer of an olefin having 2 to 3 carbon atoms than a corresponding amount of either member of the. two component additive system by itself.

15. A composition according to claim 14 wherein the metal of the first component is selected from the group consisting of iron, cobalt, nickel, chromium, titanium, vanadium, manganese, copper, zirconium' an-d tiff a-nd; when the first component is a chelate of a beta- diketone the. diketone is 2 , 4-pentanedione .

16. A composition according to claim 15 wherein the first component is -(·&■)■τ I.

17. A composition according to claim 16 wherein the second component is -^a).-. II.

18. A composition according to claim 17 wherein the organic carboxylic acid is free of non-hydrocarbon sub-stituents .

19. A composition according to claim 18 wherein at least two of R^, 1*2/ 13» R4 and R5 are hydrogen and the rest are selected from the group consisting of hydrogen, lower alkyl, halogen, lower alkoxy, benzoyl and phenyl and Rg is selected from the group consisting of lower alkyl, phenyl, halophenyl and phenoxy.

20. A composition according to claim 19 wherein the second component is a ketone.

21. A composition according to claim 15 wherein the first component is £b}_. I·

22. A composition according to claim 21 wherein the second component is -(·&·) . II.

23. A composition according to claim 22 wherein at least two of R^, R2, R3, R4 and R^ are hydrogen and the rest are selected from the group consisting of hydrogen, lower alkyl, halogen, lower alkoxy, benzoyl and phenyl and Rg is selected from the group consisting of lower alkyl, phenyl, halophenyl and phenoxy.

24. A composition according to claim 22 wherein the second component of the additive is a ketone.

25. A composition according to claim 20 wherein the metal is iron.

26. A composition according to claim 20 wherein the metal is cobalt.

27. A composition according to claim 20 wherein the metal is titanium.

28. A composition according to claim 20 wherein the metal is zirconium. 29· A composition according to claim 1 wherein the metal is titanium. P. O. Box 33116 , Tel-Aviv Attorneys for Applicant