A new recycling process for polyethylene

Abstract

Recycling of waste materials has become an increasingly common practice in recent decades. Recycling of plastic materials is important and is widely practiced in many industries and households around the world. Many everyday items, such as bottles, bags, products, especially liquid food board-based packages, are made from plastic materials. It is important to regenerate and reuse polymers. The recycled polyethylene composition (P) comprises a) at least 50% by weight of recycled polyethylene (A) and b) 0.5-15% by weight of an ethylene copolymer (B) containing hydrolyzable silicon-containing groups, and the recycled polyethylene composition (P) is blended, and the polyethylene composition (P) after blending has an MFR2 of 0.4-4 g / 10 min.

Description

[Technical field]

[0001] The present invention relates to a process for recycling post-consumer and / or post-industrial polyethylene compositions. Further, the present invention relates to recycled post-consumer and / or post-industrial polyethylene compositions having improved melt flow rate. [Background technology]

[0002] Waste recycling has become an increasingly common practice in recent decades. Recycling of plastic materials is important and is widely practiced in many industries and households around the world. Many everyday items, such as bottles, bags, products, especially liquid food board-based packaging, are made from plastic materials. It is important to regenerate and reuse polymers.

[0003] However, the quality of recycled plastics needs to be monitored and guaranteed. A particularly important objective in the recycling of polyethylene is to meet the requirements of processing properties. Polyethylene is recycled from various processes. Recycled polyethylene has been used at least once. Reclaimed polyethylene comes from post-consumer and / or post-industrial uses. Most recycled plastics are mixed into a single stream and are collected and processed by resource recovery facilities. At the resource recovery facility, the material is sorted, washed, granulated, and packaged for resale. Plastics can be sorted into individual materials such as high density polyethylene (HDPE) or poly(ethylene terephthalate) (PET), or into mixed streams of other common plastics such as polypropylene (PP), low density polyethylene (LDPE), poly(vinyl chloride) (PVC), polystyrene (PS), polycarbonate (PC), and polyamide (PA). The single or mixed streams can then be further sorted, washed, and reprocessed into pellets suitable for the selected purpose. Although recycled plastics are largely sorted into homogenous streams and washed with aqueous and / or caustic solutions, the final reprocessed stream remains contaminated with other plastics and various stream properties. For example, in a recycled polyethylene stream, small amounts of polypropylene will almost always be present.

[0004] One particular stream from post-consumer recycling is liquid food board packages, including liquid packaging boards. This stream includes liquid packaging boards with and without an aluminum layer or other oxygen barrier layer. These packages have an inner layer of plastic. The purpose of this layer is to preserve the liquid food, which may be milk, juice, or any other liquid or semi-liquid food, and to seal the package. This layer is food approved and is typically LDPE. Next to this layer there may be a barrier layer to prevent oxygen diffusion, an adhesive layer to either the paper board or the aluminum, or another oxygen barrier layer. The aluminum layer is used as an oxygen barrier. The paperboard layer is typically on the outside of the optional aluminum layer. There is an outer layer, typically made of polyethylene, and an optional adhesive layer to the board. The liquid packaging boards in liquid food board packages are complex, with each layer having a different purpose. Most layers / structures include polyethylene. Most of the polyethylene is LDPE, but linear low density polyethylene (LLDPE) is also used. Additionally, the adhesive layer may be made from ethylene methacrylic acid copolymer (EMAA), ethylene acrylic acid copolymer (EAA) or maleic anhydride grafted polyolefin (MAH). The adhesive layer typically comprises a polar polymer. The adhesive layer may be treated by ozone treatment to increase the polarity and therefore the adhesion to the aluminum layer. The stream further comprises HDPE, which is generally derived from the ground cap.

[0005] Delamination of liquid packaging board for liquid food board packages is typically done at a paper mill where the paper fibers are removed with water and regenerated.

[0006] For liquid packaging boards without an aluminum layer, the remaining mixture includes a mixture of laminated polyethylene film and rigid plastic components used in caps and closures, typically containing primarily HDPE. The recycled polyethylene stream is in the form of flakes.

[0007] In other cases of liquid packaging boards with an aluminum layer, the remaining mixture includes a mixture of strongly laminated foils of polyethylene and aluminum, which further includes a hard plastic component used for the caps and closures, typically containing mainly HDPE.

[0008] The foil can be separated by several methods such as that disclosed in US Pat. No. 5,399,663. An improved version thereof is disclosed in US Pat. No. 5,399,663, which describes an acid-based stripping process. Stripping is carried out in an organic acid solution at high temperature. Examples of organic acids are acetic acid or formic acid. The aluminum and polyethylene layers are separated. The recycled polyethylene stream is free of aluminum residues and is in the form of flakes.

[0009] Another process for stripping includes a mixture of water, a carboxylic acid, a carboxylate salt, and a passivating agent and is described in U.S. Patent No. 5,399,633. U.S. Patent No. 5,399,633 describes a mixture of water, a carboxylic acid, a phosphoric acid, and an alkali metal. A further method includes water, a swelling agent, an anionic surfactant, a carboxylic acid, and at least one of a co-surfactant or hydrotrope and is described in U.S. Patent No. 5,399,633.

[0010] The properties of recycled streams vary. Thus, the usefulness of recycled polyethylene varies. One solution to this is to test the properties of every lot. However, this is difficult, costly, and impractical. To ensure consistent properties of recycled polyethylene streams, a resilient solution must be found that ensures that the recycled polyethylene meets the application specifications.

[0011] US Patent No. 5,393,633 and US Patent No. 5,393,633 disclose compositions using different types of polyethylene and polyethylene with silane groups, both of which require virgin polymer.

[0012] Therefore, there is a need for processes to upcycle post-consumer and post-industrial polyethylene.

[0013] As used herein, the term "recycled polymer" refers to a polymer that has been used for a previous purpose and then recovered for further processing.

[0014] As used herein, the term "post-consumer" refers to a source of a material that occurs after the ultimate consumer has used the material in a consumer good or product.

[0015] As used herein, the term "post-consumer recycle" (PCR) refers to materials that are produced after the end consumer has used the material and disposed of the material in the waste stream.

[0016] As used herein, the term "post-industrial" refers to sources of materials that occur during the manufacture of a good or product.

[0017] As used herein, the term "recycled polyethylene" can refer to recycled polyethylene, or polyethylene derived from post-consumer recycled polyethylene or post-industrial polyethylene, that is intended for use as a raw material in the manufacture of new products.

[0018] To be labeled as polyethylene, it must contain at least 50% by weight ethylene monomer. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] U.S. Patent No. 5,421,525 [Patent Document 2] Chinese Patent No. 101891903 [Patent Document 3] U.S. Patent Application Publication No. 2021 / 086406 [Patent Document 4] European Patent No. 3554834 [Patent Document 5] U.S. Patent No. 10,682,788 [Patent Document 6] International Publication No. 2002 / 088239 [Patent Document 7] U.S. Patent Application Publication No. 2005 / 0049335 Summary of the Invention [Problem to be solved by the invention]

[0020] The present invention relates to a process for producing a polyethylene composition (P) from recycled polyethylene. In particular, the present invention relates to a process for providing a polyethylene composition (P) from recycled polyethylene having a lower MFR (Melt Flow Rate) than the recycled polyethylene used as starting material for the polyethylene composition (P).

[0021] When polyethylene is recycled, the MFR is inherently affected, which reduces the usefulness of recycled polyethylene, as many applications require a defined, typically low, MFR.

[0022] In industrial production of virgin polyethylene, the MFR is controlled by production parameters. Therefore, there is no need to change the MFR of virgin polyethylene. However, since the MFR is inherently affected in recycling, it is desirable to provide a means for controlling the MFR in recycling polyethylene in order to facilitate reuse of recycled polyethylene. Furthermore, a means for controlling the MFR of recycled polyethylene means that it is easier to mix different batches of recycled polyethylene.

[0023] The object of the present invention is to reduce the MFR of the recycled polyethylene composition (P). [Means for solving the problem]

[0024] Reclaimed polyethylene products are often reprocessed into pellets suitable for selected purposes. Process streams from single or mixed sources of polyethylene products can be used for granulation. Granulation means blending plastics and pelletizing them. This can affect the MFR of the plastic, which is commonly referred to as degradation of the plastic, but recombination of the degraded pieces at least partially compensates for the degradation.

[0025] However, it has been found that by introducing an ethylene copolymer (B) containing hydrolyzable silicon-containing groups, the MFR can be reduced during compounding, thereby compensating for the effects of degradation. Examples of suitable ethylene copolymers (B) are disclosed, for example, in European Patent Application No. 2582743. Compounding is preferably carried out in a compounder in which the polymers are mixed. Compounding is carried out in a suitable extruder with efficient mixing. A suitable level of mixing is required to obtain a homogeneous polymer melt and uniform polymer properties.

[0026] The recycled polyethylene of the present invention is intended for various applications, such as film blowing, pipe extrusion, injection blow molding, injection molding and extrusion foaming applications. At least some of these applications require a low MFR of the recycled polyethylene composition (P). Furthermore, these applications benefit from the flexibility that comes from adjusting the MFR.

[0027] In some applications, recycled polyethylene is blown into film. This process requires that the MFR2 of the recycled polyethylene is low, e.g., 5 g / 10 min or less, and controlled. The melt strength of the recycled polyethylene depends on the MFR and homogeneity of the recycled polyethylene composition (P). To blow the film, strain hardening is required. If the recycled polyethylene composition is not homogeneous, the film's cells will split or become unstable. To produce blown films, cell homogeneity is important. This is difficult for heterogeneous materials obtained from recycling, especially post-consumer recycling (PCR). When polyethylene is recycled, chain scission can occur. The short chains formed by chain scission can increase the MFR of the recycled polyethylene. This affects the melt strength of the recycled polyethylene. However, even though the short chains can recombine in various ways to at least partially compensate for the initial chain scission, it is beneficial to adjust the MFR to compensate for the effects of degradation by using an ethylene copolymer (B) containing hydrolyzable silicon-containing groups.

[0028] The MFR2 for applications such as film blowing is typically less than 5g / 10min. Recycled polyethylene can also be used in other applications such as pipe extrusion, injection blow molding, injection molding and extrusion foaming applications. The MFR is important for the processing properties and mechanical strength of the final product.

[0029] In pipe applications, melt strength is important for the dimensional stability of the pipe. When the pipe is extruded, there is molten polymer inside the pipe wall. If the melt strength is low, the molten polymer will flow inside the pipe wall, resulting in a thick bottom of the pipe. A low MFR is required to meet the mechanical properties of the pipe.

[0030] Thus, the present invention relates to a process for regenerating a polyethylene composition (P) from recycled polyethylene (A) and a copolymer (B), the recycled polyethylene composition (P) comprising: a) at least 50% by weight of recycled polyethylene (A); b) 0.5 to 15% by weight of an ethylene copolymer (B) containing a hydrolyzable silicon-containing group; Includes.

[0031] The process for regenerating a polyethylene composition (P) from recycled polyethylene (A) and copolymer (B) includes a step of blending the recycled polyethylene composition (P). The recycled polyethylene composition (P) treated with 0.5 to 15 wt % of ethylene copolymer (B) containing a hydrolyzable silicon-containing group has an MFR2 that is at least 15% lower than that of the recycled polyethylene (A).

[0032] The object of the present invention is to control or reduce the MFR of the recycled polyethylene composition (P). The recycled polyethylene (A) can be obtained from various recycling processes. An example of recycled polyethylene (A) is recycled polyethylene, which can be obtained from post-consumer recycling and / or post-industrial recycling. The physical properties of recycled polyethylene depend on the source. Therefore, the object of the present invention is to provide an efficient, simple, and reliable control of the MFR of recycled polyethylene. This object is achieved by adding a sufficient amount of ethylene copolymer (B) containing hydrolyzable silicon-containing groups. The recycled polyethylene composition (P) contains at least 0.5 wt. %, for example 0.5-15 wt. %, of ethylene copolymer (B) containing hydrolyzable silicon-containing groups.

[0033] Compounding of polyethylene compositions is a well-established technique, therefore, one advantage of the present invention is that it can be carried out on existing extrusion equipment.

[0034] The present invention further relates to a recycled polyethylene composition (P). The recycled polyethylene composition (P) comprises: a) at least 50% by weight of recycled polyethylene (A); b) 0.5 to 15% by weight of an ethylene copolymer (B) containing a hydrolyzable silicon-containing group; Including, The recycled polyethylene composition (P) is blended. After blending, the polyethylene composition (P) has an MFR2 of 0.4 to 4 grams / 10 minutes.

[0035] Furthermore, the present invention also relates to a recycled film comprising a recycled polyethylene composition (P), which comprises (as described above) a) at least 50% by weight of recycled polyethylene (A); b) 0.5 to 15% by weight of an ethylene copolymer (B) containing a hydrolyzable silicon-containing group; Includes.

[0036] The recycled polyethylene composition (P) is obtained by blending the above-mentioned recycled polyethylene composition (P).

[0037] The film is formed from a recycled polyethylene composition (P).

[0038] The present invention also relates to the use of an ethylene copolymer (B) containing a hydrolyzable silicon-containing group as an MFR modifier for a recycled polyethylene composition (P), the recycled polyethylene composition (P) comprising: a) at least 50% by weight of recycled polyethylene (A); b) 0.5 to 15% by weight of an ethylene copolymer (B) containing a hydrolyzable silicon-containing group; Includes.

[0039] Furthermore, the present invention relates to the use of an ethylene copolymer (B) containing hydrolyzable silicon-containing groups as a compatibilizer modifier for a recycled polyethylene composition (P). In an embodiment relating to such a use, the recycled polyethylene composition (P) comprises: a) at least 50% by weight of recycled polyethylene (A); b) 0.5 to 15% by weight of an ethylene copolymer (B) containing a hydrolyzable silicon-containing group; Includes.

[0040] The recycled polyethylene (A) contains at least LDPE, HDPE, and / or various polar polyethylenes from the adhesive layer, and possibly other polymer fractions. The ethylene copolymer (B) containing hydrolyzable silicon-containing groups acts as a compatibilizer to create a continuous matrix with melt strength. One effect of the ethylene copolymer (B) is to increase homogeneity. The formed recycled polyethylene composition (P) has one phase that binds all the parts together, including the HDPE. Another effect is that the entire matrix is ​​stressed during film blowing. [Brief description of the drawings]

[0041] [Figure 1] 4 shows a photograph of the film of Comparative Example 4, RPM40. [Diagram 2] Photographs of film of Example 7, RPM60, are shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] In one embodiment, the amount of recycled polyethylene (A) in the polyethylene composition (P) is at least 75 wt.%, preferably at least 80 wt.%, or most preferably 90 wt.%.

[0043] The recycled polyethylene (A) preferably has an MFR2 of 1 to 15 g / 10 min, more preferably 5 to 12 g / 10 min.

[0044] The addition of the copolymer (B) containing hydrolyzable silicon-containing groups reduces the MFR of the recycled polyethylene composition (P). In a preferred embodiment of the present invention, the MFR2 of the recycled polyethylene is at least 20% lower, more preferably at least 30% lower, compared to the recycled polyethylene (A).

[0045] The polyethylene composition (P) shall be added up to 100%. The polyethylene composition (P) may further comprise additives, pigments and other polymer fractions. The polyethylene composition (P) may comprise a pigment, preferably carbon black. This increases the density of the recycled polyethylene composition (P). The additives are preferably added using a masterbatch. If further polymer fractions are added to the recycled polyethylene composition (P), a suitable virgin polyethylene is added. Most preferably, no further polymer fractions are added.

[0046] In one embodiment, the amount of copolymer (B) containing hydrolyzable silicon-containing groups in the polyethylene composition (P) is from 1 to 10 wt%, more preferably from 2 to 7 wt%, and most preferably from 2 to 5 wt%.

[0047] The amount of copolymer (B) to be added is determined in relation to the desired MFR of the recycled polyethylene composition (P). The desired MFR of the polyethylene composition (P) is determined by the intended end use of the recycled polyethylene composition (P). The recycled polyethylene composition (P) preferably has an MFR2 of 0.4 to 10 grams / 10 minutes, more preferably 0.4 to 4 grams / 10 minutes, and most preferably 1 to 3 grams / 10 minutes. It is an object of the present invention to have a small amount of copolymer (B) containing hydrolyzable silicon-containing groups. This improves the compounding process. This results in a simpler, more stable, and more homogeneous composition. The amount of hydrolyzable silicon-containing groups in the polyethylene is 0.1 to 5 weight percent, more preferably 0.5 to 2 weight percent.

[0048] In an embodiment of the present invention, the ethylene copolymer containing hydrolyzable silicon-containing groups (B) is a low density polyethylene (LDPE). The LDPE can be either recycled or virgin. Virgin means that the polymer has not been used, i.e., has not been recycled. Due to the lack of recycled ethylene copolymer containing hydrolyzable silicon-containing groups (B), it is most suitable to use a virgin source. LDPE is produced by a high pressure process. Another reason for using virgin ethylene copolymer containing hydrolyzable silicon-containing groups (B) is that it reduces reactivity with use. That is, recycled ethylene copolymer containing hydrolyzable silicon-containing groups has low reactivity.

[0049] The present invention is preferably free of peroxides and / or peroxide residues. Peroxides and / or peroxide residues can arise from various steps of reactive compounding. Polyethylene can be treated by reactive compounding with peroxides to reduce the MFR. Peroxides crosslink the polyethylene chains, extending the molecules. Peroxide residues have a strong odor and are messy to handle. Furthermore, crosslinking can lead to the deleterious formation of microgels. One objective of the present invention is to avoid peroxides and their residues.

[0050] In a preferred embodiment of the present invention, the entire process is free of peroxides or peroxide residues. The copolymer (B) containing hydrolyzable silicon-containing groups is preferably free of peroxides or peroxide residues. The copolymer (B) containing hydrolyzable silicon-containing groups is preferably polyethylene, preferably LDPE produced by high pressure process.

[0051] In another embodiment of the present invention, copolymer (B) containing hydrolyzable silicon-containing group is grafted polyethylene.Polyethylene can be grafted with silane-containing group, such as ethylene-vinylsilane, which is well known in the art.Because grafting of polyethylene typically requires the use of peroxide, the embodiment that includes the use of polyethylene grafted with silane-containing group by the use of peroxide is less preferred.

[0052] In a preferred embodiment of the present invention, the recycled polyethylene composition (P) does not contain a silane condensation catalyst, such as dibutyltin dilaurate (DBTL) or dioctyltin dilaurate (DOTL). Both DBTL and DOTL are organotin compounds. Organotin compounds are recognized as potentially toxic. Another example of a silane condensation catalyst is sulfonic acid. The purpose of the silane condensation catalyst is to crosslink hydrolyzable silicon-containing groups by a condensation reaction. Silane condensation catalysts are preferably avoided because they are harmful to the environment or contain strong acids. It is an object of the present invention to provide a regeneration process for polyethylene composition (P) in which no silane condensation catalyst is added throughout the regeneration process. Thus, the recycled polyethylene composition (P) does not contain a silane condensation catalyst.

[0053] It is an object of the present invention that articles made from the recycled polyethylene composition (P) are substantially odorless and comparable in terms of odor and mechanical properties to articles made from virgin polyethylene.

[0054] The recycled polyethylene (A) preferably comprises LDPE, LLDPE and / or HDPE. Polyethylene such as LDPE, LLDPE and / or HDPE is the main component of the recycled polyethylene (A). Thus, the recycled polyethylene (A) may comprise at least 50% by weight, for example at least 60% by weight, at least 70% by weight, at least 80% by weight, or at least 90% by weight of LDPE, LLDPE and / or HDPE. The recycled polyethylene (A) may further comprise an acidic moiety such as EMAA, EAA, MAH grafted polyolefin and / or low molecular weight organic acid. In a more preferred embodiment, the low molecular weight organic acid is a residue from the stripping process. Examples of low molecular weight organic acids are formic acid and acetic acid.

[0055] The recycled polyethylene (A) can be obtained from post-consumer recycling. The recycled polyethylene (A) can also be obtained from post-industrial recycling. In a preferred embodiment, the recycled polyethylene (A) is from post-consumer recycling. This is a more demanding process since the recycled polyethylene (A) is a mixture of various polyethylenes and is contaminated by other mixed streams of other common plastics.

[0056] In a preferred embodiment, the recycled polyethylene (A) is obtained from post-consumer recycling of liquid food board based packages, including liquid packaging boards. The liquid food board packages may or may not have an aluminum layer. Most preferably, the liquid food board packages have an aluminum layer. It is noted that all streams derived from the PCR stream have a high degree of recycled polymer from other streams.

[0057] The properties of recycled polyethylene vary. The density of recycled polyethylene varies from 890 kg / m 3 ~990kg / m 3The recycled polyethylene composition (P) may be of any color, but is mostly pigment-free. The ash content may be less than 2% by weight, and the recycled polyethylene composition (P) is typically in pellet or granular form. The moisture content may be less than 0.1% by weight. Most of the properties of the recycled polyethylene composition (P) are the same as those of the recycled polyethylene (A).

[0058] (experiment) FIG. 1 shows a photograph of the film of Comparative Example 4, RPM40, and FIG. 2 shows a photograph of the film of Inventive Example 7, RPM60.

[0059] (Measurement method) The melt flow rate (MFR) is determined as MFR2 according to ISO 1133 and is given in g / 10 min. MFR is a measure of the flowability and therefore the processing properties of a polymer. The higher the melt flow rate, the lower the viscosity of the polymer. MFR2 of polyethylene is measured at a temperature of 190° C. and a load of 2.16 kg. All examples of compositions containing at least 50% by weight of polyethylene are measured at 190° C. The melt flow rate is preferably measured according to ISO 1133-2:2011.

[0060] Complex viscosity was measured at 190 °C using a TA Instruments ARES-G2 TA rheometer. The configuration is a 25 mm plate / plate geometry at 1% strain. The frequency sweep is from 100 to 0.1 rad / sec.

[0061] The extensional viscosity was measured using a TA Instruments ARES-G2 rheometer equipped with an extensional viscosity fixture (EVF) at 150° C. The extensional rate (Hencky rate) was 0.5 1 / s and the final Hencky strain was 3.4.

[0062] Light microscopy was performed using a Dino-Lite digital microscope at 20x magnification.

[0063] (material) The EVS is LE-4423 available from Borealis. EVS is a low density polyethylene copolymer containing hydrolyzable silicon-containing groups. The copolymer is produced in a high pressure reactor. The density of the polymer is 923 kg / m 3 and has a MFR2 of 1.0 g / 10 min.

[0064] Recycled polyethylene 1 has a MFR2 of 8.7g / 10min. The polymer is obtained by collecting various liquid food board based packages from packages that mainly have layers of board, polymer and aluminum. First the board layers are separated and then the aluminum layer is separated by an acid based stripping method before regranulation. The liquid food board packages originate from PCR and contain the following regranulated polymers: LDPE>LLDPE>Ethylene-co-acrylic acid and / or co-methacrylic acid>HDPE>PET>MAH grafted polyolefins and pigments. The PCR further contains contaminants that are reduced by melt filtration during the regranulation process.

[0065] Recycled polyethylene 2 has a MFR2 of 4.2g / 10min. The polymer is obtained by collecting various liquid food board based packages from packages that mainly have layers of board, polymer and aluminum. First the board layers are separated and then the aluminum layer is separated by an acid based stripping method before regranulation. The liquid food board packages originate from PCR and contain the following regranulated polymers: LDPE>LLDPE>Ethylene-co-acrylic or co-methacrylic acid>HDPE>PET>MAH grafted polyolefins and pigments. The PCR further contains contaminants that are reduced or removed by melt filtration during the regranulation process.

[0066] Recycled polyethylene 3 has an MFR2 of 4.4g / 10min. The polymer is obtained by collecting various liquid food board based packages from packages that mainly have layers of board, polymer and aluminum. First the board layers are separated and then the aluminum layer is separated by an acid based stripping method before regranulation. The liquid food board packages originate from PCR and contain the following regranulated polymers: LDPE>LLDPE>Ethylene-co-acrylic or co-methacrylic acid>HDPE>PET>MAH grafted polyolefins and pigments. The PCR further contains contaminants that are reduced or removed by melt filtration during the regranulation process.

[0067] Recycled polyethylene 4 has an MFR2 of 3.6g / 10min. The polymer is obtained by collecting various liquid food board based packages from packages that mainly have layers of board, polymer and aluminum. First the board layers are separated and then the aluminum layer is separated by an acid based stripping method before regranulation. The liquid food board packages originate from PCR and contain the following regranulated polymers: LDPE>LLDPE>Ethylene-co-acrylic or co-methacrylic acid>HDPE>PET>MAH grafted polyolefins and pigments. The PCR further contains contaminants that are reduced or removed by melt filtration during the regranulation process.

[0068] LDPE-22 is 1922NO and is commercially available from Sabic. The polymer is produced in a tubular reactor and is virgin with no additives. The density of the polymer is 919 kg / m 3 and has a MFR2 of 22 g / 10 min.

[0069] LDPE-7 is 19N430 and is commercially available from Ineos. The density of the polymer is 920 kg / m 3 and has a MFR2 of 7.5 g / 10 min.

[0070] LDPE-1 is LDPE 320E, available from Dow. The density of the polymer is 925 kg / m 3and has a MFR2 of 1 g / 10 min. EXAMPLES

[0071] The compositions shown in Table 1 were compounded in a single screw extruder SSE (Axon BX-25) at 220 rpm equipped with a water bath at room temperature prior to pelletizing the strands. Extruder temperature settings were 170, 220, 220, 220, 220, 220°C.

[0072] [Table 1]

[0073] In Comparative Example 1, the change in MFR2 was measured in a polymer composition having only recycled polyethylene 1. In Table 1, all examples were preheated for 5 minutes before measuring MFR2.

[0074] In Comparative Example 2, only EVS was used. MFR2 remains the same. In Inventive Examples 1-3, recycled polyethylene 1 was mixed with different amounts of EVS. MFR2 decreases with the amount of EVS added.

[0075] The relative difference is calculated as the ratio of the MFR2 of the recycled polyethylene composition (P) divided by the MFR2 of the recycled polyethylene (A) minus 100%.

[0076] The examples in Table 2 were compounded in a single screw extruder SSE (Axon BX-25) at 220 rpm equipped with a water bath at room temperature prior to pelletizing the strands. Extruder temperature settings were 170, 220, 220, 220, 220, 220°C.

[0077] [Table 2]

[0078] In Table 2, all examples were preheated for 5 minutes before measuring MFR2. The results are consistent with those in Table 1.

[0079] The extruder and process conditions in Table 3 are the same as in Table 2.

[0080] [Table 3]

[0081] Table 3 discloses further examples of the present invention.

[0082] The complex viscosity change was measured in Table 4. The compositions were compounded in a single screw extruder SSE (Axon BX-25) at 220 rpm with temperature settings of 170, 220, 220, 220, 220, and 220° C. before being pelletized into strands. The samples were then compression molded in a hydraulic press. Press temperature 155℃ A cylindrical sample (diameter 25 mm and thickness 1 mm) was prepared with the following time: preheating 2 min, total pressure 2 min, and cooling 5 min.

[0083] The complex viscosity was measured at 190 °C. The configuration was a 25 mm plate / plate geometry at 1% strain. The frequency sweep was from 100 to 0.1 rad / s.

[0084] [Table 4]

[0085] The addition of EVS to recycled polyethylene increases the complex viscosity of the composition, which is evidence of molecular expansion and shear thinning of the recycled polyethylene composition (P).

[0086] Table 5 reports the effect of EVS on extensional viscosity for recycled polyethylene 2. The effect of strain hardening (higher melt elasticity and viscosity) for the inventive examples can be observed.

[0087] [Table 5]

[0088] This example illustrates the improved melt elastic properties of the present invention.

[0089] Additional examples of virgin LDPE with different MFR2 blended with EVS are shown in Table 6. Compositions were made according to Table 1.

[0090] [Table 6]

[0091] The addition of EVS to virgin LDPE reduces the MFR2, which is due to the lower MFR2 of EVS, and is significantly lower than that observed for the inventive examples.

[0092] Additional film examples were produced in a laboratory scale film blowing machine. The examples in Table 7 demonstrate the improved film forming properties of the present invention. The recycled polyethylene compositions from Comparative Example 4 and Inventive Examples 6 and 7 were compounded in an air-cooled, single screw Brabender & Collins extruder 19 / 25D equipped with a barrier screw 2.5:1 with mixing elements. The extruder revolutions per minute (RPM) was varied. Film blow die head with cooling ring (diameter 2cm) Temperature settings (profile): 190-210-210-210℃

[0093] [Table 7]

[0094] The examples show that stable film production can be achieved with the present invention: the MFR is reduced and the blowability is improved.

[0095] The micrograph of the film blown from the recycled material without EVS (Comparative Example 4) shows a heterogeneous material with separate phases. The dispersed phase is elongated in the machine direction due to the orientation effect at the die exit. During film blowing, the continuous phase is stressed and since this phase is only a part of the total volume, the stress in this phase becomes too high and it breaks easily. The micrograph with 5% EVS added shows a homogeneous material. EVS acts as a compatibilizer that makes the phase boundaries uniform. This means that the entire volume of the material can absorb the stress due to the mechanical interaction of the phases. Therefore, the film blowing properties of Inventive Examples 6 and 7 are improved.

Claims

1. A process for regenerating a polyethylene composition (P), comprising the steps of: The recycled polyethylene composition (P) a) at least 50% by weight of recycled polyethylene (A); b) 0.5 to 15% by weight of an ethylene copolymer (B) containing hydrolyzable silicon-containing groups; Including, The process includes a step of blending the recycled polyethylene composition (P), wherein the recycled polyethylene composition (P) treated with 0.5 to 15 wt % of an ethylene copolymer (B) containing a hydrolyzable silicon-containing group has an MFR that is at least 15% lower than that of the recycled polyethylene (A). ２ A process having

2. 2. The process according to claim 1, wherein the amount of recycled polyethylene (A) in the recycled polyethylene composition (P) is at least 75% by weight, preferably at least 80% by weight.

3. 3. The process according to claim 2, wherein the amount of the ethylene copolymer (B) containing hydrolyzable silicon-containing groups in the recycled polyethylene composition (P) is 1 to 10% by weight.

4. The process according to any one of claims 1 to 3, wherein the ethylene copolymer (B) comprising hydrolyzable silicon-containing groups is a LDPE.

5. 5. The process of claim 4, wherein the ethylene copolymer (B) containing hydrolyzable silicon-containing groups is free of peroxides or peroxide residues.

6. 2. The process of claim 1, wherein the recycled polyethylene composition (P) does not contain a silane condensation catalyst.

7. 2. The process of claim 1, wherein the ethylene copolymer (B) containing hydrolyzable silicon-containing groups is a grafted polyethylene.

8. The process of claim 1, wherein the recycled polyethylene (A) comprises LDPE, LLDPE, and / or HDPE.

9. 9. The process of claim 8, wherein the polyethylene composition (P) comprises acidic moieties.

10. 10. The process of claim 9, wherein the acidic moiety comprises EMAA, EAA, MAH-grafted polyolefin and / or low molecular weight organic acid.

11. The process of any one of claims 8 to 10, wherein the recycled polyethylene is obtained from liquid food board-based packaging.

12. A recycled polyethylene composition (P), comprising: a) at least 50% by weight of recycled polyethylene (A); b) 0.5 to 15% by weight of an ethylene copolymer (B) containing hydrolyzable silicon-containing groups; Including, The recycled polyethylene composition (P) is blended, and the recycled polyethylene composition (P) after blending has an MFR of 0.4 to 4 g / 10 min. ２ The recycled polyethylene composition (P) has:

13. A recycled film, wherein the recycled film is obtained by molding the recycled polyethylene composition (P) according to claim 12 into a film.

14. MFR for recycled polyethylene composition (P) ２ Use of an ethylene copolymer (B) containing hydrolyzable silicon-containing groups as a modifier, The recycled polyethylene composition (P) a) at least 50% by weight of recycled polyethylene (A); b) 0.5 to 15% by weight of an ethylene copolymer (B) containing hydrolyzable silicon-containing groups; Including, use.

15. Use of an ethylene copolymer (B) containing hydrolyzable silicon-containing groups as a compatibilizing modifier for a recycled polyethylene composition (P), comprising: The recycled polyethylene composition (P) a) at least 50% by weight of recycled polyethylene (A); b) 0.5 to 15% by weight of an ethylene copolymer (B) containing hydrolyzable silicon-containing groups; Including, use.

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