Sustainable plastic product

Abstract

The invention relates to a plastic article comprising a plastic body, wherein the plastic body is formed from a plastic composition comprising a plasticizer, a filler, and a thermoplastic vulcanizate (TPV) based on a polypropylene thermoplastic (PP) and a cross-linked ethylene propylene diene monomer (EPDM) rubber, characterized in that the plastic composition contains at least 65% by weight of recycled, bio-based, and / or bioattributed raw materials, based on the total weight of the plastic composition. The plastic article according to the invention is characterized by a reduced ecological footprint, without negatively affecting its mechanical properties.

Description

[0001] The invention relates to a plastic article comprising a substantially cylindrical hollow body, wherein the hollow body is formed from a plastic composition comprising a plasticizer, a filler and a thermoplastic vulcanizate (TPV) based on a polypropylene thermoplastic (PP) and a cross-linked ethylene propylene diene rubber (EPDM).

[0002] Technical plastic articles, such as those used in the automotive or industrial sectors, often feature a plastic body made of commercially available thermoplastic vulcanizates (TPVs). A common and commercially widespread type of these TPVs is an alloy of fully vulcanized ethylene propylene diene monomer (EPDM) rubber dispersed in a polypropylene (PP) phase. The production of such TPV materials is generally based on conventional, petroleum-based raw materials. For example, TPV (EPDM+PP) materials are typically characterized by the following raw materials: polypropylene, EPDM masterbatch (EPDM rubber, paraffin oil, fillers such as carbon black and / or minerals, antioxidants), and a crosslinking system.

[0003] The high consumption of non-renewable raw materials and the associated CO2 emissions in the value chain lead to a lack of sustainability in the resulting product.

[0004] The invention was therefore based on the objective of reducing the CO2 footprint of the TPV plastic article without negatively affecting its mechanical, chemical and physical properties.

[0005] The problem was solved by the features of the independent claims. Further advantageous embodiments are disclosed in the dependent claims.

[0006] According to the invention, the plastic article has a substantially cylindrical hollow body, the hollow body being formed from a plastic composition. Such plastic bodies can be, for example, bellows, shock absorbers, hoses, or flexible containers, particularly for use in an automobile. In particular, the bellows is a bellows, an air spring bellows, a steering bellows, etc. The plastic composition comprises at least a plasticizer, a filler, and a thermoplastic vulcanizate (TPV) based on a polypropylene thermoplastic (PP) and a cross-linked ethylene propylene diene monomer (EPDM) rubber. The plastic article is characterized in that the plastic composition contains at least 65% by weight, preferably at least 70% by weight, and particularly preferably at least 80% by weight of recycled, bio-based, and / or bioattributed raw materials, based on the total weight of the plastic composition.

[0007] Such a plastic article is primarily characterized by a better environmental footprint, which is evident from the calculated product carbon footprint (PCF). The PCF is the sum of greenhouse gas emissions caused directly and indirectly by a product. It is calculated by adding up the emissions from each phase of a product's life cycle (e.g., material production, manufacturing, use, and disposal). Based on the raw materials of the plastic article, the PCF of the embodiment according to the invention can already be reduced by approximately 60%.

[0008] In principle, all PPs known to a person competent in the field, in particular PP homopolymers, are suitable for use in the TPV according to the invention. In preferred embodiments, the PP comprises at least 60 wt.%, preferably at least 80 wt.%, and particularly preferably 100 wt.% recycled PP (rPP), in each case based on the weight of the crude polymer.

[0009] Likewise, all EPDM rubbers known to a competent person can be used for application in TPV. In preferred embodiments, the EPDM has an ethylene content of more than 55 wt.%, in particular more than 65 wt.%, based on the weight of the EPDM.

[0010] Alternatively or additionally, the ethylene in the EPDM comprises more than 50 wt.%, preferably more than 60 wt.%, and particularly preferably more than 70 wt.%, bio-based or bioattributed ethylene, in each case based on the weight of the crude polymer. For example, the ethylene can be obtained from a naturally renewable raw material, e.g., sugar cane. The proportion of the bio-based component can be determined using ASTM D6866, Carbon-14 method.

[0011] According to the invention, the EPDM is crosslinked. Plastic articles according to any one of claims 1 to 6, wherein the EPDM is crosslinked with a phenolic resin system. In macromolecular chemistry, crosslinking refers to reactions in which a multitude of individual macromolecules are linked to form a three-dimensional network. Crosslinking can be achieved either directly during the synthesis of the macromolecules or through reactions on existing polymers. The crosslinking process alters the properties of the crosslinked materials. Generally, an increase in hardness, toughness, and melting point, as well as a decrease in solubility, is observed. This change increases with the degree of crosslinking, i.e., the proportion of crosslinked sites relative to the total polymer amount. A crosslinking agent is characterized by at least two reactive groups. The EPDM can be crosslinked by any suitable agent known to a person competent in the field.

[0012] Preferably, the EPDM is crosslinked with a phenolic resin. The structure of phenolic resins used for crosslinking elastomers varies according to the reaction conditions used to produce them. Suitable resins are known, for example, from DE69723406T2.

[0013] In preferred embodiments, the plastic composition also comprises a plasticizer, wherein the plasticizer is a bio-based, bioattributed, or recycled plasticizer. Plasticizers cause plastics, e.g., thermoplastic or elastomeric polymers, to be softer, more flexible, more supple, and more elastic. For the purposes of the invention, these are external plasticizers, i.e., chemical components added to the system that do not form covalent bonds with the matrix-forming polymer. In principle, all plasticizers known to a person skilled in the art and compatible with the system used are suitable. Suitable plasticizers generally have a molecular weight of 50 g / mol to 3000 g / mol. Preferably, the plasticizer is bio-based or bioattributed. Plasticizers selected from the group consisting of soybean oil, castor oil, paraffin oil, and mixtures thereof are particularly suitable.

[0014] In preferred embodiments, the plastic composition also includes a filler, wherein the filler is kaolin, carbon black, silica, or mixtures thereof. Fillers are insoluble particulate additives in the micro- to nanometer range, which are added to the plastic composition in higher concentrations (>10 phr). These serve, among other things, to significantly improve or substantially enhance mechanical, chemical, or electrical properties. Alternatively or additionally, the fillers are at least partially recycled, bio-based, or bioattributed fillers. Fillers or filler mixtures comprising at least carbon black particles are particularly preferred for the purposes of the invention.

[0015] Preferably, the plastic composition contains 15 to 100 phr, particularly 20 to 50 phr, of one or more fillers. Alternatively or additionally, the plastic composition contains 50 to 135 phr, particularly more than 50 phr and less than 100 phr, of a plasticizer. Alternatively or additionally, the plastic composition contains 50 to 200 phr of PP per 100 phr EPDM, according to the TPV requirements profile. The quantity "phr" (parts per hundred rubber) is familiar to those with expertise in this field and requires no further explanation. The choice of quantities should preferably be made in accordance with sustainability criteria and in consideration of the required mechanical properties. For example, a higher quantity of the plasticizer would be chosen if it is a bio-based variant.

[0016] In addition, the TPVs contain additives customary according to the invention, which are necessary for processing, coloring, conductivity, etc. Such additives are known to a person skilled in the art and do not require separate mention in this invention.

[0017] Thermoplastic polymers (TPVs) are generally produced using dynamic vulcanization. In a special mixing unit, the elastomer is crosslinked in the presence of suitable systems (e.g., peroxides, sulfur systems, resin crosslinking systems, etc.) and, due to high shear forces, is very finely dispersed within the thermoplastic matrix. High crosslinking and high dispersion, combined with good bonding of the elastomer phase to the thermoplastic matrix, are prerequisites for a high level of performance. Elastomer alloys with TPV properties can also be produced directly by incorporating the already vulcanized elastomer into the thermoplastic material through compounding under high shear stress, such as in a twin-screw extruder (TSE). Such processes are familiar to qualified personnel. Examples:

[0018] Two mixtures according to the invention (mixture 1 and 2) were prepared according to the recipes listed in Table 1 and then vulcanized. Table 1: Plastic compositions according to the invention ingredient Description Mixture 1 in phr Mixture 2in phr rPP recycled polypropylene homopolymer (MFR2.5 g / 10 min) 175 65 EPDM 4% Dien, 5 Mooney viscosity, 70% bio-based ethylene from sugar cane 100 100 filler kaolin 40 40 soot 9 9 Networking system Alkylphenol resin 12 12 Other additives 7 7 Oil recycled base oil 84 84 427 317

[0019] Simultaneously, a comparison compound based on conventional petroleum-based and non-sustainable raw materials was produced and also vulcanized. The tested mechanical properties (density, hardness, tensile strength, tensile elongation) differed from each other by no more than 10%. In particular, the compression set was improved by approximately 10% with the sustainable compounds.

[0020] The PCF (cradle-to-gate according to life-cycle assessment) was calculated for the raw mixtures as an example, in accordance with ISO 14040 and ISO 14067. This results in 2.0 CO2 eq. / kg for the standard mixture and only 0.8 CO2 eq. / kg for the sustainable mixtures. The PCF has already been reduced by 60% in this step. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 69723406T2

[0012]

Claims

[1] Plastic article comprising a plastic body, wherein the plastic body is formed from a plastic composition comprising a plasticizer, a filler and a thermoplastic vulcanizate (TPV) based on a polypropylene thermoplastic (PP) and a cross-linked ethylene propylene diene rubber (EPDM), characterized by that the plastic composition contains at least 65% by weight of recycled, bio-based and / or bioattributed raw materials. [2] Plastic article according to claim 1, wherein the EPDM has an ethylene content of more than 55 wt.%, in particular more than 65 wt.%, based on the weight of the crude polymer, and wherein the ethylene of the EPDM comprises more than 50 wt.%, preferably more than 60 wt.%, particularly preferably more than 70 wt.%, bio-based or bioattributed ethylene, in each case based on the weight of the crude polymer. [3] Plastic articles according to one of claims 1 or 2, wherein the PP comprises at least 60 wt.%, preferably at least 80 wt.%, particularly preferably at least 100 wt.% recycled PP (rPP), in each case based on the weight of the raw polymer. [4] Plastic article according to any one of claims 1 to 3, wherein the plastic composition further comprises a plasticizer and wherein the plasticizer is a bio-based, bioattributed or recycled plasticizer. [5] Plastic article according to claim 4, wherein the plasticizer is selected from the group consisting of soybean oil, castor oil, paraffin oil and mixtures thereof. [6] Plastic articles according to any one of claims 1 to 5, wherein the filler is kaolin, carbon black, a silica or mixtures thereof. [7] Plastic articles according to any one of claims 1 to 6, wherein the EPDM is crosslinked with a phenolic resin system. [8] Plastic articles according to any one of claims 1 to 7, wherein the plastic composition comprises 15 to 60 phr of one or more fillers and 50 to 120 phr of a plasticizer. [9] Plastic article according to any one of claims 1 to 8, wherein the plastic body is designed as a substantially cylindrical hollow body. [10] Plastic article according to claim 9, wherein the plastic article is a bellows, in particular a bellows or an air spring bellows, a shock absorber, a hose or a flexible container.