Patent Application
20230405982
This present invention is in the field of materials science and relates to Recycled and Recyclable Barrier laminate tube.
Million tons of plastic packaging are in circulation every year around the world. Plastics are a rapidly growing segment of municipal solid waste (MSW) and take centuries to break down in landfill or the ocean. Alternative recyclable plastics are becoming attractive for closing the loop of plastics. Many studies suggest recycled plastics contain over 25% w/w less green-house/carbon gas emissions than virgin resins. The more PCR resins you include in your products, the higher impact you can make on saving the environment. Recyclable plastics should be collected, sorted, and recycled to reduce landfill, conserve energy and environment. Nowadays, there are available technologies of mechanical recycling machines that proven recyclate quality as a lever for the circular economy.
Post-consumer resin from such containers contains contaminants of paper and other plastic resins, for example, from closures such that it has been generally thought that it cannot be used to make satisfactory plastic containers. Washing process for plastic recycling is mainly for eliminating all contaminants from materials. For highly contaminated material, e. g. to remove adhesives from labels, and to meet food grade standards, hot washing stage may be required. In a continuous hot washer, the flakes are soaked in a mixture of hot water washing solution, followed by a friction washer where the material is rinsed. Caustic solution and detergent are the option to be added in some cases for enhancing the de-contamination of inks or glues. Recycling technologies proven for FDA compliant recycled plastic for food-grade packaging are highly recommended for food and cosmetic industries.
Post-industrial recycled materials (PIR) are a product composition that contains some percentage of manufacturing waste material that has been reclaimed from a process generating the same or a similar product. Those materials are high level of quality and consistency.
Post-consumer recycled materials are generated by the final consumer (residential or non-residential) after it has served its intended use and has been collected for reuse or recycling, not include materials and by-products generated from and commonly used within an original manufacturing process (PIR). In the use of plastic materials for containers such as bottles, it has been found desirable to attempt to recycle and reuse the plastic which is commonly known as post-consumer plastic (PCP) or post-consumer resin (PCR). It has been suggested that such post-consumer resin be utilized because large quantities of high-density polyethylene post-consumer resin are available due to the extensive use of high-density polyethylene in large containers for milk and household products.
The use of post-consumer recycled plastics such as polyethylene and polypropylene depend on the pellet properties of reprocessing plastics. Processing stability, density, melt index, tensile yield, flexural modulus, and impact resistance are critical to determine the quality of the recycled resins and should fulfill requirements of converters.
Specifically, when containers are made from post-consumer high-density polyethylene homopolymer or copolymer (HDPE) container scraps, it has been found that the containers have diminished physical properties and particularly diminished resistance to stress cracking. Such containers made of high-density polyethylene have been used for packaging of certain types of liquid detergent products. The use of such containers to package liquid detergent products has been somewhat restricted, however, by reason of the fact that many types of liquid detergent products accelerate the tendency of the container to exhibit stress cracking.
Stress cracking is evidenced by the appearance of hazy cracks in the container which are aesthetically unpleasing to the ultimate consumer. In extreme cases, stress cracking can lead to leakage of the contents from the container. Stress cracking can occur when the containers are for liquid products including liquid detergents and liquid hypochlorite bleaches.
PCR resins can be alternatively made from the mixed wastes with the rejects and residues from other mechanical or material recycling operations. Mixed waste, including multilayer LDPE, LLDPE, HDPE, polypropylene and a smaller amount of polystyrene can be used as raw materials for chemically recycled pyrolysis oil and purified hydrocarbons. The latest technology by integrated process of pyrolysis and purification to obtain pyrolysis oil feedstock. Further fractionation and distillation are used to separate into three different fractions: heavy vacuum gas oil (HVGO), diesel, and light vacuum gas oil (LVGO). The LVGO is then used to produce plastic monomers and chemicals such as benzene, toluene, xylene etc. The recycled raw materials as monomers will be fed into the plastic production cycle, thereby partially replacing fossil resources. The share of recycled raw material is allocated to the final product by using a certified mass balance approach. The final properties of PCR resin made from pyrolysis are expected for a food grade resin using in food packaging.
Available filtration in mechanical recycling process is an option for producing food grade resins using in food packaging. As a result, recyclate can be converted into plastic products replacing virgin raw materials.
Moreover, the criteria of HDPE design guide are considerably important for recyclable tube. Previously, the ratio of low-density polyethylene is higher than high-density polyethylene in laminate tube, which does not meet the critical value in HDPE design guide. The recyclable tube should consist of at least 50% w/w of high density polyethylene for better compatible with HDPE recycling stream.
In case of functional barriers in polyolefin containers, there are allowed for <5-6% w/w of ethylene vinyl alcohol and 3% w/w of PE-g-MAH tie layers for full compatibility. Other barrier combinations should be evaluated and tested for determining the plastic packaging recyclability.
Accordingly, among objectives of the present invention are to provide a blend of post-consumer resin from high density polyethylene containers and the like which will have substantial resistance to stress cracking and which will have minimal reduction in other physical properties permitting its use for various kinds of containers, that is for containing various products.
U.S. Pat. No. 5,712,009 revealed the invention related to coextruded multilayer and blow molded plastic container. The side wall consists of a thin outer layer, a thin intermediate opaque layer comprising a blend of post-consumer resin, and a relatively thick inner plastic layer. In a modified and preferred form, a fourth inner layer of virgin polyethylene polymer is provided.
U.S. Pat. No. 6,960,375 disclosed a bottle having at least three layers in which the outer and inner layers contain a metallocene polyethylene polymer and the middle layer comprises virgin high-density polyethylene, regrind and post-consumer recycled resin, with the bottle having at least 10% light transmittance in the visible spectrum.
U.S. Pat. No. 8,083,064 invented a container with a sustainable, recyclable, two-year shelf life substantially free of virgin petroleum-based compounds, the invention comprising: (a) a container; (b) a cap; (c) a label. The composition of the container consists of a blend of virgin resin, regrind resin, post-consumer recycle resin, post-industrial plastic resin and renewable plastic resin.
U.S. Pat. No. 8,475,900 disclosed a high-content PCR HDPE container comprising: a blend of PCR HDPE, impact modifier, and elastomer.
U.S. Pat. No. 10,214,639 disclosed a laminate comprising of an outer layer of a post-consumer recycled polymer composition consisting of a post-consumer recycled resin, and ethylene alpha olefin copolymer. The post-consumer recycled resin is a High-Density Polyethylene (HDPE) resin.
The present invention relates to the recyclable laminate tube and using recycled resin in packaging tubes that can be used in personal, home, or skin care products and a method of making the recyclable and recycled plastic packaging tubes to increase the demand of environmental awareness tube packaging.
A laminated tube comprising of post-industrial and/or post-consumer recycled resin and the amount of the blends to provide acceptable tube performances and recyclability. The use of recycled resin is to reduce the carbon footprint of packaging tube and closed-loop recycling. The present invention utilizes a layer of multilayer flexible sheet to produce recyclable packaging by the selection of virgin plastics.
The present invention discloses the recyclable tube with a post-consumer recycled (PCR) resin addition comprising of 15% to 70% (w/w) of PCR resin and 30% w/w to 85% w/w of virgin polyolefin resin.
The first embodiment of the present invention provides a recycled and recyclable multi-layer packaging tube comprising the following composition:
The second embodiment of the present invention provides a recycled and recyclable metalized multi-layer packaging tube comprising the following composition:
The another embodiment of the present invention provides the plastic container set forth in claim 1 or 2 wherein said recycled resin comprises at least 15% w/w of the fusion blend.
The present invention relates to a process of manufacturing tubes comprising of blown film extrusion of PCR resin comprising of 15% w/w to 70% w/w of PCR resin and 30% w/w to 85% w/w of virgin polyolefin resin. Extrusion lamination of film with molten barrier resin is disclosed for increasing barrier properties of the tube package.
A tube package containing up to a 5% layer weight by weight of EVOH with a minimum of 32 mol % ethylene can be compatible with the residential postconsumer HDPE recycling stream.
A multilayer recyclable tube should have high-density polyethylene content in the total structure higher than 50% w/w in the tube for achieving overall density and melt index of HDPE stream.
In accordance with the invention, a plastic container made from a fusion blend of recycled resin and a high-density polyethylene copolymer resin. The recycled resin can be primarily a post-consumer high-density polyethylene and may contain small amounts of colored plastic containers. The physical properties of the container including stress crack resistance are maintained as contrasted to the loss of such physical properties that have been heretofore resulted from the use of post-consumer resins. Preferably, PCR-HDPE is used in the blend formulation without direct contact to the food products. In case of chemical recycling PCR resin, the resin quality is high due to relatively low contaminants and safe for direct food contact.
In accordance with the invention, pellets of a PCR high density polyethylene resin and pellets of a virgin high-density polyethylene copolymer were mixed and fusion blended. Containers were blow molded and subjected to testing for stress cracking, top load and drop impact.
SABIC is also offering a new SABIC HDPE booster grade to help incorporate PCR or increase the existing PCR content in containers from 30% w/w to 60% w/w. This is without facing degradation and processing issues, while minimizing quality variations on machine efficiency. The resulting packaging aims to meet processing and quality standards of the industry, contributing further to circularity by saving on virgin materials.
The blends of the present invention contain about 15-70% weight by weight of post-consumer resin and about 30-85% weight by weight of virgin high-density polyethylene copolymer resin.
Post-consumer resin contains primarily the plastic from high density polyethylene homopolymer containers used for packaging milk and small amounts of colored plastic containers and possible polypropylene resin from syrup bottles, multi-layer ketchup bottles and caps. Such post-consumer resin has the properties set forth in the following Table 1. In contrast, the PIR-HDPE resin properties are easier to select due to the known resin properties, except for the cleanness of PIR-HDPE itself.
Generally, the overall HDPE content in the laminate tube (body and shoulder) is approximately less than 50% w/w. The recyclability of the laminate tube with HDPE content less than 50% w/w is not good enough to include the tube into HDPE recycling stream. The recycled pellet properties do not meet the requirements in the recycling industry. The requirement includes extrusion evaluation, pellet testing, physical and mechanical properties, bottle production and testing.
Recyclable tube can be achieved by adding more than 50% w/w HDPE in the laminate tube. The HDPE resin selection has been shown in Table 2. Each HDPE resin has unique properties; however, the HDPE selection should pay attention to the melt index lower than 4 g/10 min at 190 degree Celsius, 2.16 kg. Preferably, HDPE resin should have melt index in between 0.3-2.5 g/10 min at 190 degree Celsius, 2.16 kg.
The tube stiffness between conventional plastic tube and recyclable tube is shown in the Table 3. By using the universal tensile testing machine, the push-pull gauge with speed 100 mm/min at the distance half the diameter of the tube is used to measure the tube stiffness in unit gram force. It is found that recyclable is slightly stiffer than the conventional plastic barrier laminate tube. This is caused by an increase of HDPE content in laminate tube.
To achieve tube recyclability in HDPE or PE recycling stream, overall density and melt index of tube flake/pellet should meet density >0.941 g/cm3 and melt index <0.75 g/10 min.
The virgin high density copolymer resin contains linear high-density ethylene polymer. The linear high-density ethylene copolymer included in the blends will have a density of at least about 0.94 g/ml, a melt index of less than about 0.5 g/10 min. and will have polymerized therein at least about 98 mol % ethylene with any comonomer polymerized therein being an alpha-mono olefin containing about 3 to 12 carbon atoms. Such linear high-density ethylene polymers are known and reported in the art and are commercially available from numerous commercial producers. Such linear high-density ethylene polymers are prepared by polymerizing ethylene, optionally in the presence of an alpha-mono olefin comonomer containing 4 to 12 carbon atoms in the presence of certain metallic catalysts such as chromium catalysts, e. g. CrO3 supported on silica-alumina supports, and the Ziegler-Natta catalysts, e.g. TiCl3 employed in conjunction with certain aluminum alkyl cocatalysts. The requisite density and melt index desired in the polymer are obtained by proper control of polymerization conditions including temperature, pressure, comonomer concentration. The preferred linear high-density ethylene polymers will have a density of at least about 0.94 g/ml. The especially preferred polymers will have a density of at least about 0.95 g/ml. Stress crack resistance is conventionally conducted with test methods as established by Technical Bulletin PBI 11-1978 of the Plastic Bottle Institute, Rev. 1-1991 or ASTM D2561-70 (Reapproved 1989).
Antioxidant masterbatch is used for improving oxidation resistance during processing or recycled resin. Preferably, 1% w/w of antioxidant masterbatch is added into the resin formulation.
Suitable linear low-density polyethylene (LLDPE) includes copolymers of ethylene and α-olefins. Alpha-olefins includes 1-butene, 1-hexene, and 1-octene, and mixtures thereof. LLDPE is commercially available.
Suitable high-density polyethylene (HDPE) includes ethylene homopolymer and copolymer of ethylene and α-olefins. Suitable alpha-olefins includes 1-butene, 1-hexene, and 1-octene, and mixtures thereof. HDPE is commercially available.
Suitable recycled HDPE or post-consumer HDPE resins should have melt flow rate less than 1 g/10 min for easy blending with virgin HDPE resins.
The process of orientation is employed to impart desirable properties to films, including making cast films tougher (higher tensile properties). Depending on whether the film is made by casting as a flat film or by blowing as a tubular film, the orientation process requires substantially different procedures.
Blown films of HDPE resins tend to have greater stiffness and toughness. In contrast, cast films usually have the advantages of greater film clarity and uniformity of thickness and flatness, generally permitting use of a wider range of polymers producing a highly quality film.
Polyethylene films preferably containing HDPE are oriented up to four times in the machine direction to give films having good dead-fold and water-vapor barrier characteristic making them suitable for packaging tube, particularly for further laminated with other polyethylene layer by using adhesive or extrusion lamination.
When the film has been stretched in a single direction (monoaxial orientation), the resulting film exhibits better strength and stiffness along the direction of stretch, but it is weak in other direction, i.e., across the stretch, often splitting or tearing when pulled.
Metallization is the process to deposit aluminium vapor on film substrate providing shiny and metallic look like a mirror. Regarding to enhance process performance, high barrier metallization for foil replacement and increase shelf life, higher surface energy and better surface energy retention of the vacuum deposited layer as well as high metal adhesion/bond strength are critical requirements. High demand in metal adhesion levels which are greater than 200 g/15 mm, or even up to 600 g/15 mm appeared to be more requested. Most adhesives typically fail around 200-300 g/15 mm in the laminate structure.
This is due to the fact that, the single layer metal adhesion frequently measured by seal/peel tests with ethylene acrylic acid (EAA) film, delamination in the laminate structure can take place at the metal-polymer interface at a lower bond strength value than obtained in the EAA peel test. Therefore, the type of laminate structure (duplex/triplex), adhesive as well as the sealant web type and thickness are important and will impact to the failure behavior. Conventional inline plasma pre-treatment can achieve outstanding metal adhesion beyond the levels. Moreover, selecting the technology that involves the deposition of a hybrid coating layer, which has a tailored coating stoichiometry & gradient that exhibits drastically enhanced anchoring properties to the base polymer substrate. Even at very high optical density (OD) levels, where it is typically more difficult to achieve good adhesion levels.
The film substrate for metallization can be polyester, polypropylene, or polyethylene, however in this case, it should be polyolefin for further laminate with other layers and made it fully recyclable.
Coextrusion blown film with at least three-layer for outer layer are used for providing good tensile strength and puncture resistance. In the embodiments, the multilayered film comprises of one or more polymeric materials such as low-density polyethylene, linear low-density polyethylene, high density polyethylene, copolymer of ethylene and propylene. Recycled HDPE resin and post-consumer HDPE resin should be added in the middle layer of the inner film layer. The recycled content should not be as high as lowering the mechanical properties of the outer layer. One embodiment of the invention is a five-layer film: polyolefin/tie/EVOH/tie/polyolefin. One embodiment of the invention is a seven-layer film: polyolefin/HDPE/tie/EVOH/tie/HDPE/polyolefin.
The substrate for aluminium metallization may comprise any one or more polyolefin materials suitable for use in multilayer structure. Such materials include, for example multilayer blown or cast film with unoriented, monoaxial oriented, or biaxial oriented polyolefins, and any combination of two or more thereof. Five-layered blown film of PE/Adhesive/EVOH/Adhesive/PE can be used for enhancing the protection of the metallic layer from delamination by absorption of substances in the filled products.
The metallization on the top surface of the substrate (skin layer) may be accomplished using an appropriate technique. In the embodiments, the skin layer is pretreated, such as corona treatment and plasma treatment, prior to metallization. Metallization may be done by a physical vapor deposition process. In such processes, the metal is heated and evaporated under vacuum. The metal then condenses on the skin layer.
The resulting metallized skin layer exhibits an optical density of at least 2.0. The optical density of the metallized skin layer may be from 2.0 to 2.8. Any appropriate metal can be used, depending on the final application used for the multilayer film/sheet. Commonly used metals include aluminium, nickel, and chromium.
Recycled HDPE resin and post-consumer HDPE resin should be added in the middle layer of the inner film layer which is not direct contact with other layers.
Tie resins are selected based on the layers being bonded, the melt index, process conditions, secondary operations (e. g. orientation) and the cost. The melt index should be selected so that the layers in contact have similar viscosities; otherwise, the flow instabilities can lead to waviness or poor layer distribution. Generally, the interior layer should have the highest viscosity while the outer or skin layer should have the lowest viscosity. A suitable tie-layer adhesive is maleic-anhydride grafted polyolefins or derivatives thereof.
Barrier resin which is Ethylene-vinyl alcohol copolymer (EVOH) and its derivatives are employed as a barrier to oxygen. Ethylene content in the EVOH resin should be lower than 35 mol % to provide enough oxygen barrier to the laminate tube. However, EVOH with a minimum of 32 mol % ethylene can be compatible with the residential postconsumer HDPE recycling stream.
Coextrusion blown film with at least three-layer are used for providing good tensile strength and puncture resistance. In the embodiments, the multilayered film comprises of one or more polymeric materials such as low-density polyethylene, linear low-density polyethylene, high density polyethylene, copolymer of ethylene and propylene. Recycled HDPE resin and post-consumer HDPE resin should be added in the middle layer of the inner film layer. One embodiment of the invention is a five-layer film: polyolefin/tie/EVOH/tie/polyolefin. One embodiment of the invention is a seven-layer film: polyolefin/HDPE/tie/EVOH/tie/HDPE/polyolefin.
By switching virgin resin to recycled resin, the recyclable and recycled tubes can be succeeded by using the present invention's concept. Moreover, the addition of additive such as calcium carbonate filler in the laminate tubes should be avoided due to the change in density property greater than 1. The tube flake with density greater than 1 will sink during sink/float recycling process. The loss of the precious plastic wastes is counted into lower recyclability percentage.
The following part explains the invention in details using examples, but the invention is not to be considered limited to what is shown in these examples.
Three-layered blown film is made for outer film by incorporating 70% w/w of PCR-HDPE in the core layer of the film. Three-layered blown film is made for inner film by incorporating 70% w/w of PCR-HDPE in the core layer of the film. Thereafter, outer film is laminated with inner film by using co-extrusion lamination of LLDPE/Tie/EVOH/Tie/LLDPE. The virgin or recycled HDPE content to other PE-based resins in total tube structure should have higher than 50% w/w. HDPE resin should have melt index less than 1. EVOH resin should have ethylene content higher than 32 mol % and melt index should be less than 5 g/10 min. The EVOH content in total structure should be less than 5% w/w.
Three-layered blown film is made for middle film by incorporating 70% w/w of PCR-HDPE in the core layer of the film. Three-layered blown film is made for inner film by incorporating 70% w/w of PCR-HDPE in the core layer of the film. The middle film with the thickness of 90 micron evaporated on one side with metal is adhesive-laminated outer polyethylene film (40 micron) by using an adhesive agent. Next, this laminate film is further laminated with inner polyethylene film (120 micron) by using extrusion lamination with hot-melted resins of LLDPE, tie, and ethylene vinyl alcohol (EVOH). The virgin or recycled HDPE content to other PE-based resins in total tube structure should have higher than 50% w/w. EVOH resin should have ethylene content higher than 32 mol % and melt index should be less than 5 g/10 min. The EVOH content in total structure should be less than 5% w/w.
Gel defects may occur from contamination, unmelt, un-mix, or thermal degradation. All plastic resins degrade a function of time, temperature, and shear conditions. In this case, recycled resin used in the present invention may play an important role for gel defect. Gel counts on laminate tube are done manually by naked eye.
Gels/dots defects on tube that might be from recycled resin are acceptable for customer due to the aim to close the loop of recycling. The purpose of recycling is to minimize or completely avoid sending waste to landfill or incinerator.
Oxygen transmission rate is measured at 25 degree Celsius and 0% relative humidity by using ASTM F1307-02, a machine from Illinois Model 8001 L. Water vapor transmission rate is measured at 38 degree Celsius and 90% relative humidity by using ASTM F1249-06. Recycled plastic laminate tube with 24% w/w of PCR-HDPE is found that contaminants/unmelts/thermal degradation of recycled resin slightly affect to the oxygen barrier property.
As stated above in the detailed description of this application.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2101002007 | Apr 2021 | TH | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/TH2022/000013 | 3/31/2022 | WO |
