WO2012125101A1

WO2012125101A1 - A package made of a polymer comprising pro-oxidant filler material

Info

Publication number: WO2012125101A1
Application number: PCT/SE2012/000033
Authority: WO
Inventors: Gunnar Forsberg; Louis D. HARTLEY
Original assignee: Esp Solutions Ltd.
Priority date: 2011-03-14
Filing date: 2012-03-13
Publication date: 2012-09-20

Abstract

The present invention relates to a package of a polymer, wherein it comprises an addition of a pro-oxidant in the form of a filler material comprising an integrated chitin and calcium carbonate amount having a biological origin.

Description

A package made of a polymer comprising pro-oxidant filler material

DESCRIPTION

Technical field

The present invention relates to a polymer package material having restricted life-time by ultimately becoming self-destructive, said package substantially being made of polyolefins, such as polyethylene and/or polypropylene, in particular it relates to a package becoming both self-destructive thru photo (light) and thermo impact.

Background of the invention

Most polymeric package materials can be retrieved in one or more of three basic ways, 1 ) thru collection and recycling of the material, 2) by bacterial biological decomposition of the material and 3) thru energy retrieval by using, the material as a fuel.

In general packages of all kinds are often disposed of outdoors in a natural

environment and cause an accumulating environmental problem. Or they are disposed of using nature as part of an organized compost program. In any case they are made subject to biological degradation by weather conditions, rain, ice, snow, heat and cold, by UV photo-radiation, by micro-organisms (different creatures) that are able to digest (bio-assimilate) polymers and their by-products, by mechanical means, and other factors. In addition to the disposal issues polymeric packaging materials are mainly produced from non-renewable raw materials. These are obtained from a non-sustainable material source, which have a potential negative effect on the climate-climate change and the carbon footprint in C0₂ kg equivalent. A sustainable material could be described as allowing a lower carbon impact or footprint aimed at conserving and maintaining resources with the purpose of renewable and re-utilization of available resources.

Most packages that currently exist in retail are packages having a weight of up to around 100 g, independent of size, including a number of different food packages. Among these are bags for carrying food and other house-hold articles, food packages as such, e.g., food trays, wrapping films, bags, and others, flower and plant pots and flower wrappings (usually cast polypropylene film), vegetable wrappings (polyethylene and cast polypropylene films), bags for sweets and snacks. In general polyolefins are used at the manufacture of such packages, such as polyethylene, polypropylene, poly vinyl acetate and polystyrene. Other polymers used are polyvinyl chloride (PVC), and polystyrene (PS). The polymers can be produced in different ways, including being blown or expanded forms to provide a voluminous end product for insulating (impact or temperature) purposes. Polymer Degradation and Stability 80 (2003) 39-43, 1. Jakubowicz, "Evaluation of degradability of biodegradable polyethylene (PE)" discloses a study of thermo-oxidative degradation of polyethylene films containing pro-oxidants at three different temperatures, whereby the parameter oxygen concentration was varied as well. The paper discloses that polyolefins are hydrophobic hydrocarbon polymers, and thereby they are resistant to hydrolysis and cannot be considered as hydrobiodegradable. Polyolefins, as commercial products, are moreover resistant to oxidation and biodegradation due to the additional presence of antioxidants and stabilizers.

However, the polyolefins can be made oxobiodegradable by the use of pro-oxidants accelerated additives. Such pro-oxidants can be based on metal combinations capable of yielding two metal ions of similar stability and with oxidation number differing by one unit, e.g., Mn²⁺/Mn³⁺. The material will thereby degrade by a free radical chain reaction involving atmospheric oxygen. The primary products are hydroperoxides, which can either thermolyse or photolyse under the catalytic action of a pro-oxidant , leading to molecular chain scission and the production of low molecular mass oxidation products such as carboxylic acids, alcohols, ketones and low molecular mass hydrocarbon waxes. Peroxidation leads also to hydrophilic surface modification; this allows the surface to become favorable to micro-organisms, which can then bio-assimilate the low molecular mass oxidation products. It is also stated that degradation in compost of PE that contain pro-oxidants could be very slow due to the high moisture - low partial pressure of oxygen. The tests performed were carried out at temperatures of 50, 60, and 70°C. The paper shows that the films tested that the calculate lifetime for the materials, defined as time to achieve 10,000 molecular weight, and if assumed 25°C as in-use temperature, then, using the determined activation energy it will be found that it will take about 4.5 years for one of the materials and approx. 2.5 years for one of the materials (containing the double active ingredient) to reach this limit. WO 2006/009502 discloses such a oxobiodegradable polyolefin product being based on the addition of a pro-oxidant in the form of at least one salt of a metal of the group consisting of Mn, Fe, Cu, Co, and Ni, whereby the polyolefin is provided with a filler in the form of a mineral, such as calcium carbonate, such as talc, crushed marble, chalk, including nano particles thereof, calcite, silica, and nano particle clays Or as a filler material in the form of natural fiber such as cellulose fiber, wood fiber, powderous wood or china grass, rice spelt, and starch. This provide the starch is a needed ingredient In order to achieve as optimum result as possible in the oxidation phase providing degradation and fragmentation, it is preferable to have as larger surface as possible on the object allowing more surface area available for the oxygen and by implication a more effective and faster degradation. The starch on the surface material will attract microbes to digest this organic material, thus increase the surface area. However the use of starch has turned out to show some production drawbacks in that this material needs to be very dry (kept dry), i.e., to have only a low percentage moisture content of only a small percentage not to provide an uneven polymer product, the required low moisture content of the starch may in turn lead to a risk of dust explosions. Further more the starch for industrial applications is a product which will compete with general food production for people and animals, utilizing existing arable land and available water for farming. One base crop to produce starch is corn (zea maize) which also uses synthetic fertilizers, toxic pesticides which will lead to an overall detrimental influence on the soil and the environment. Chitin has proved to be a better and more effective alternative to starch. Chitin is mainly derived from marine shells, but may also be recovered from cockroach. In shellfish production the disposal of the marine waste, mainly the eco-shell, currently creates an environmental and economic disposal problem for the producers. In addition there are legal restrictions on how to handle this waste. This has led to amplified interest in biotechnology research concerning the identification and extraction of additional high grade, low-volume by-products produced from shellfish waste treatments. Shellfish waste consists of crustacean exoskeletons, which is primarily a mix of protein, biogenic calcium and chitin. Chitin is a long-chain polymer of /V-acetyl glucosamine, a derivative of glucose, which is found in many places throughout the natural world. It is the main component of the cell walls of fungi, the exoskeletons of arthropods such as crustaceans (e.g. crabs, lobsters and shrimps) and insects, the radulas of mollusks and the beaks of cephalopods, including squid and octopuses. Chitin may be compared structurally to the polysaccharide cellulose and functionally to the protein keratin. Chitin has the general formula

Chitin may be recovered from the above mentioned species by well-known methods and is produced in large industrial scale from these particular crustaceans. These shells are subjected to an acid treatment, washing, alkali treatment, destaining, washing, drying and grinding. The process temperature is kept between 30 and 90°C.The fractionated chitin is then subjected to further refining.

A commercially produced chitin and calcium carbonate filler of biological origin, such as from oyster shells will contain a given amount of CaCOadue to the specie from which it is derived from in the form of calcite and aragonite. Chitin and calcium carbonate filler from marine sources also contains the A-vitamin Retinol being a strong photo-oxidant. Further the ground marine shell will contain proteins, most probably connective tissue proteins, which can be eliminated wholly or partially using a proteinase. Thus the protein is either integrated with the chitin structure and/or the calcium carbonate structure.

Chitin is known to have three polymorphic solid-state forms designated as a-, 13-and T- chitin. a-Chitin is the most abundant form, found in shellfish and also in fungal cell wall, although the comparatively lower degree of acetylation of chitin in fungi makes it less rigid. In the solid state, adjacent a-chitin chains are organized in an anti-parallel configuration in the c direction.

13-Chitin is found in chitin extracted from the diatom spines and squid pens. Unlike a- chitin, but as with cellulose, 13-chitin is packed in a parallel arrangement that does not favor the inter-chain hydrogen bonding between the C-6 hydroxyl groups along the c- axis, otherwise present in a-chitin.

Little is known of the solid-state structure of T-chitin except that it is a mixture of a- and 13- chitin, with two parallel chains and for every anti-parallel stack that leads to water swelling properties intermediate between a- and 13-chitin. US 2004/0062884 discloses compositions for photodegradable and biodegradable plastic product comprising a major amount of polyethylene resin, chitin, different oils, cobalt oleate and dibutyltin used as a master for mixing with polyethylene (PE) in an amount of 0.2 to 8 % by weight. The total of PE is 99.8 to 92 % by weight. The total amount of chitin is thus 0.14 to 0.56 % by weight in the final product. The product will be thermo instable due to the content of cobalt oleate which will be initiated by any light reaching the final polymer product.

The disclosure mentions that a biodegradable component is selected from chitin, casein, sodium phosphate and metal salt of hydrogen phosphate. It is not probable that the compounds mentioned having quite different origin and chemically different properties will act in the manner indicated.

Summary of the invention

To be able to meet different conditions in a degradation and biodegradation process under the presence of oxygen, aerobic biodegradation, it is desired to have an aerobic biodegradative polyolefin package which will become self-destructive thru light and temperature. Thus the present invention relates to a package of a polyolefin polymer being self-destructive by light and temperature providing many improvements, when compared to conventional so called oxobiodegradation processes. Further it provides a sustainable material source which has a positive effect on the climate change and the carbon footprint in C0₂ i.e., a sustainable material is equal to low-impact footprint aimed at conserving and maintaining resources with the purpose to renew and re- utilize resources.

Detailed description of the present invention

In particular the present invention relates to packages made by polyolefins, whereby the polyolefin(-s) has been made destructible by the addition of an Aerobic Master Batch (AMB) to provide for a short destruction time when subjected to biological degradation and being subject to common weather conditions including light and temperature, i.e., being photo and thermo sensitive.

More particular the invention relates to package of a polymer, wherein it comprises an addition of a pro-oxidant in the form of a filler comprising an integrated chitin and calcium carbonate amount having a biological origin (land based or biomarine sourced). The package of a polyolefin polymer, can besides the filler comprise an addition in the form of at least one salt of a metal of the group consisting of Mn, Fe, Cu, Co, and Ni, preferably Mn and Fe.

The term "polyolefin" used herein will also encompass other polymers used in the production of polymer packages, such as polyvinyl chloride and polystyrene.

The polyolefins are normally polyethylene (HDPE; LLDPE; LDPE; MDPE; VDLPE) and/or polypropylene. Besides the polyalkenes, polyvinyl chloride and polystyrene, foamed or not foamed, are used within the framework of the present invention.

The salt of the metal can be one or more of the carboxylates stearate, oleate, or palmitate

The content of the filler calcium carbonate and chitin can be varied.

It has turned out that the aerobic biodegradationis improved by the combination of AMB^'s, and the filler and the metal salt acting in a synergistic manner.

One major advantage of the present invention is that any package can be recovered for recycling, be biologically degraded or be energy retrieved by burning. Thus the package is not restricted to one single recycling way.

The introduction of the new aerobic biodegradation technology means that it will use less metal salts, as well as it will be considerably more cost effective due to the use of the chitin and bio calcium being a waste product, because the filler can be used in a larger quantities in comparison to conventional so called oxobiodegradation processes. This also provides for improved dispersion homogeneity, improved repeatability and thereby an improved performance. The prior art oxobiodegradable products contains active components in an amount of 5 to 20 % of additives in the master batch which gives only 0.05 to 0.4 % of active components in the final product having a mixing ratio of 1 to 2 % of the

oxobiodegradable additive. The percentage of active components in the final product using the additive and filler of the present invention, the AMB, is from 1 to 15 %, thereby being 20-30 times larger than in final products using conventional so called oxobiodegradation processes. The present additive of chitin and calcium (biological origin) carbonate improves productivity as well as it facilitates improved purge cleansing of the production equipment and a better, faster cooling of the final product produced. It is also effect of lowering the overall carbon footprint C0₂ in kg, e.g. as the raw material is biorenewable and thus the final application may be considered as more sustainable.

The chitin and calcium carbonate can be of an integrated or "united" form, i.e., the filler has been recovered from a chitin/calcium carbonate source as one fraction.

The chitin and calcium carbonate filler is pulverized to a size of at least 1 pm, preferably at most 5 pm to improve dispersion capability, however, whereby the filler may not be too large to have an impact on friction wear on the machinery used. The dispersion homogeneity is of importance as it provides for a better and faster degradation of the end product. If too little additive is used the additive will be present at very small locations in the end product in turn leading to a non-uniform degradation.

A photodegradable additive containing Chitin and Calcium Carbonate may influence the clarity by adding a white tint to the material. The whiteness would be directly related to the mixing ratio of the additive. When adding a component activated by temperature and heat under aerobic conditions to the photodegradable additive the amount of Chitin/Calcium Carbonate could be less as the active components will interact during the process and thus become complementary to each other. Thus the mixing ratio of the Chitin/Calcium Carbonate could be lower and the transparency clarity will be improved. In the production process of the final product, using the AMB, the amount of additives and fillers will affect the efficiency and the process.

In the additive master batch production of the AMB, using less components will improve the process economy and also being beneficial for the process repeatability and the final material quality.

The presence of the chitin leads to a much improved bio-performance including biodegrability due to the chitin sourced feed stock for environmental microbes. The chitin with its natural content of Retinol further leads to an improved degradation based on direct UV light (sunlight), photo degradation when compared to conventional so- called oxobiodegradation catalytic processes. The use of the chitin filler means the use of more Bio-renewable material, which in turn leads to a reduced - lower impact on the carbon footprint. Thus the invention leads to a more eco-sustainable production technique.

The present invention makes use of fewer components which leads to lower material costs. The elimination of starch means that there is no use of agro-based renewable material, because use of the chitin additive is a mere marine waste material - a renewable source.

The present invention is exemplified by the following general examples giving a Aerobic Master batch (AMB) example and a Final product example.

In the drawings

DIAGRAM 1 shows a composting test result

DIAGRAM 2 shows a sustainability test

DIAGRAM 3 shows a further sustainability test

MASTER BATCH

Ingredient Amount % by weight

Polymer 20 to 90

Metal oxidant 0.2 to 6

Chitin 7.0 to 25

CaC0₃ 0 to 50 (metal oxidant, chitin and CaC0₃ being AMB) Fatty acid ester 2 to 4

FINAL PRODUCT

Ingredient Amount % by weight

Polymer 45 to 95

AMB filler 5 to 50

Pigment 0 to 1

The invention will be described more in detail in the following, however, without being restricted thereto, with reference to the examples given. All percentages herein given are percentage per weight. Example 1

A master batch having the content

Polyethylene 22.0%

Polypropylene 7.0%

Chitin 22.0%

CaC0₃ 44.0%

Manganese stearate 1.0%

Fatty acid ester 4.0%

was prepared and pelletized.

The master batch above was used in a mixture with polyethylene in an amount of 30% of the final weight in the final mixture. The mixture was added to a blown or cast film extrusion process to produce a polymer filmweb roll wrapped onto a paper core roll, for further processing into bags.

Example 2

A master batch having the content

Polyethylene 54.0%

Chitin 18.0%

CaC0₃ 22.0

Ferric stearate 1 %

Fatty acid ester 4.0%

was prepared and pelletized. The master batch above was used in a mixture with polyethylene in an amount of 30% of the final weight in the final mixture. The mixture was added to a blown or cast film extrusion process to produce a polymer film web wrapped onto roll for further processing into bags.

Example 3

A master batch having the content

Polyethylene 58.0%

Chitin 13.0%

CaC0₃ 22.0

Manganese stearate 1%

Fatty acid ester 4.0%

Example 4

Polyethylene 21.0 %

Mn-stearate 0.3 %

Chitin 25.0 %

CaCOs 50.0 %

Fatty Acid ester 3.7 %

The master batch above was used in a mixture with polyethylene in an amount of 30% of the final weight in the final mixture. The mixture was added to a blown or cast film extrusion process to produce a polymer film web wrapped onto roll for further processing into bags.

Example 5

Polyethylene 69.3 %

Mn-stearate 2.0 %

Chitin 10.0 %

CaC0₃ 15.0 %

Fatty Acid ester 3.7 %

Example 6

Polyethylene 84.5 %

Fe-stearate 5.0 %

Chitin 7.0 %

CaC0₃ 1.0 %

Fatty Acid ester 2.5 % The master batch above was used in a mixture with polyethylene in an amount of 30% of the final weight in the final mixture. The mixture was added to a blown or cast film extrusion process to produce a polymer film web wrapped onto roll for further processing into bags.

Example 7

Polyethylene 85.5 %

Mn-stearate 2.0 %

Chitin 10.0 %

CaC0₃ 0.0 %

Fatty Acid ester 2.5 %

Example 8

A master batch containing

Polyethylene 10.0 %

Ground marine shell 76.5 % Carbon carbonate/chitin 3:1 Oyster shell

Inert material 13.5 %

was prepared Example 9

Typical plastic film blend formulation is

Master according to Example 8 10%

LLDPE 77%

LDPE 10 %

Pigment, titanium oxide 3 %

The mixture was added to a blown or cast film extrusion process to produce a polymer film web wrapped onto roll for further processing into bags. Example 10

Typical plastic film blend formulation is

Master according to Example 8 20%

LLDPE 65%

LDPE 12 %

Pigment, titanium oxide 3 %

The mixture was added to a blown or cast film extrusion process to produce a polymer film web wrapped onto roll for further processing into bags.

Example 11

Typical plastic film blend formulation

Master according to Example 8 25%

HDPE 62%

LDPE 10 %

Pigment, blue 3 %

Example 12

Typical plastic film blend formulation is

Master according to Example 8 25%

HDPE 50%

Recycled HDPE 13 %

LLDPE 10 %

Pigment, grey 2 %

Example 13

Typical plastic film blend formulation is

Master according to Example 8 25%

LLDPE 65%

LDPE 12 %

Pigment, titanium oxide 3 %

The mixture was added to a blown or cast film extrusion process to produce a polymer film web wrapped onto roll for further processing into bags. The AMB filler mixture, i.e., metal salt and chitin and calcium carbonate of marine shells filler comprises the following % by weight.

Metal salts (i.a. carboxylates of Fe, Mn, Co or Cu) 0.1-30

Chitin 1.0-45

CaCC-3 2.0-50

To produce the master batch a polymer (PE or PP and/or PS) can be added to a total amount of 15-85 % by weight of the final master batch mixture.

The AMB mixture or additive can be mixed with the main polymer base in a proportion of 1-50%.

The polyolefin content of the final product is normally 50 to 99 %.

The master batch will normally contain an addition of fatty acids or fatty acid esters, such as oleic acid, stearic acid, a lubricant such as an ester or a wax and/or a vector to improve dispersion, flowability, reducing wear on machinery, a.o. The polymer materials of the present invention may also be used in any plastic forming process method, such as injection moulding, form moulding, thermo moulding, film casting, blow moulding, cold moulding, bag moulding, vacuum thermoforming, compression moulding, slot-die extrusion or span forming. The polymer package consisting of polymer and a filler will have a very rapid ageing as evident from the table below. Sample films according to Example 13 were subjected to seven days of ASTM G 154 Cycle3 UV-B accelerated weathering. The samples were tested prior to test and after finished the seven day test period.

Table

Note: The tensile tests were each performed on 19 mm wide strip specimens using a crosshead speed of 500 mm per minute and a gagelength of 100 mm.

Below DIAGRAM 1 (attached) is shown a compost test of a polyolefin according to Example 11 according to IS014855. Test temperature was 58°C.

The test shows that the polymer provides a fairly fast composting in a comparison with pure cellulose.

In a sustainability test carried out using the master batch according to Example 8 above, it has been shown that the master batch composition has nearly 4 times less impact than polyethylene in kg. C02 equivalents. 1.28 kg C02 equivalents compared to 4.85 kg C02 equivalents for pure polyethylene. The data are shown in the

DIAGRAM 2 below.

As shown in DIAGRAM 3 below the master batch of Example 8 has approximately 2.5 times lower climate impact when using waste polyethylene material contra non-waste material.

The present polymer packages are not only subject to UV irradiation degradation, but will also be subject to a thermo-aerobic degradation. The AMB mixture disclosed above will become initiated by UV-light and be supported by UV-light in their aerobic reaction to decompose the polymers.

It is evident that the polymer package of the invention will break down fairly rapidly at higher temperatures, such as those temperatures present in commercially operated aerated industrial compost plants, where typical temperatures between 40 to 80°C are quite common.

Claims

1. A package of a polymer, wherein it comprises an addition of a pro-oxidant in the form of a filler material comprising an integrated chitin and calcium carbonate amount of a biological origin.

2. A package according to claim 1 , wherein the polymer further comprises at least one salt of a metal of the group consisting of Mn, Fe, Cu, Co, and Ni.

3. A package according to claim 1 , wherein the filler is present in the form of pulverized marine shells.

4. A package according to claim 1 and 3, wherein the filler contains integrated protein.

5. A package according to claim 1 , wherein the polymer is selected from the group of polyethylene, polypropylene, polyvinyl chloride and polystyrene.

6. A package according to claim 5, wherein the polymer is polyethylene and/or polypropylene.

7. A package according to claim 5, wherein the polymer is polyvinyl chloride or polystyrene.

8. A package according to one or more of claims 1-7, wherein the metal salt is a carboxylate.

9. A package according to claim 8, wherein the carboxylate is selected from the group consisting of a stearate, an oleate, a palmitate or mixtures thereof.

10. A package according one or more of claims 1-9, wherein the amount of the metal salt is 0.1 to 6 % by weight.

11. A package according one or more of claims 1-10, wherein the amount of the filler is 1 to 50% by weight.

12. A package according one or more of claims 1-7 and 11 , wherein the ratio between chitin and calcium carbonate of the biological origin is 1 :0.1-3.

13. A package according claim 12, wherein the ratio between chitin and calcium carbonate is 1 :0.5-2, preferably 1 :1 - 2, more preferably 1 :1.5 - 2.

14. A package according to claim 1 , wherein the filler of chitin and calcium carbonate is of cockroach origin.

15. A package according to claim 1 , wherein the filler component contains retinol.

16. A package according to claim 1 wherein the chitin and calcium carbonate filler is pulverized to a size of at least 1 μιη, preferably at most 5 μιη.