Bio-based ethylene-vinyl acetate (EVA) compositions, methods of making, and articles

Abstract

Bio-based ethylene–vinyl acetate (EVA) compositions having renewable carbon content from about 5% to about 100% (ASTM D6866) are disclosed. The compositions exhibit properties comparable to fossil-derived EVA and are processable by conventional methods. Processes are provided for producing renewable ethylene and vinyl acetate from biomass-derived ethanol and for preparing EVA resins and compounded formulations, including crosslinked foams, films, adhesives, and molded articles. Articles and uses are also disclosed.

Description

BIO-BASED ETHYLENE-VINYL ACETATE (EVA) COMPOSITIONS, METHODS OF MAKING, AND ARTICLESField of the Invention

[0001] The present disclosure relates to polymeric compositions comprising ethylenevinyl acetate (EVA) copolymers having renewable (bio-based) carbon content, to processes for preparing such compositions and their components, and to articles and uses thereof. In particular, the disclosure concerns EVA resins in which at least a portion of the ethylene and / or vinyl acetate is derived from renewable feedstocks, such as ethanol obtained from sugarcane or other biomass, as quantified by ASTM D6866 radiocarbon analysis.Background

[0002] EVA copolymers are versatile thermoplastic elastomers widely used in foams, films, adhesives, footwear, automotive components, and other applications due to their combination of flexibility, toughness, and processability.

[0003] The growing need to reduce greenhouse-gas emissions and dependance on fossil feedstocks has driven the development of bio-based polymers.

[0004] A challenge is to provide bio-based EVA that maintains the processing and performance characteristics of conventional fossil-derived EVA while enabling high renewable carbon content and compatibility with existing processing equipment.Summary

[0005] Disclosed herein are bio-based EVA compositions comprising a copolymer of ethylene and vinyl acetate having from about 5 wt% to about 49.9 wt% of vinyl acetate comonomer and a melt flow index at 190 °C / 2.16 kg from about 0.1 to about 1000 g / 10 min, wherein the copolymer has a renewable carbon content from about 5% to about 100% as determined by ASTM D6866.

[0006] Also disclosed herein are a method of making said bio-based EVA, comprising polymerizing ethylene and vinyl acetate under high-pressure free-radical conditions in a tubular and / or autoclave reactor, and optionally compounding the EVA resin with one or more additives selected from coagents, foaming agents, stabilizers, colorants, lubricants, flame retardants, fillers, and compatibilizers.

[0007] Also disclosed herein are articles comprising said bio-based EVA, the are article selected from foams, packaging, films, sheets, laminates, adhesive, automotive articles, construction articles, footwear components, industrial mats, mattresses, sports protection gear, gaskets, seals, flooring, household, toys, caps, closures, furniture and fragranced Items.Brief Description of Certain Terms

[0008] As used herein, "renewable carbon content" refers to the fraction of carbon in a material that is derived from biomass, as determined according to ASTM D6866. Unless otherwise indicated, numerical ranges include all values and subranges within the stated range. Unless specified, all percentages are by weight.Detailed DescriptionBio-based EVA Resins

[0009] The bio-based EVA compositions of the present invention comprises copolymer of ethylene and vinyl acetate having from about 5 wt% to about 49.9 wt% of vinyl acetate comonomer and a melt flow index at 190 °C / 2.16 kg ranging from about 0.1 to about 1000 g / 10 min, wherein the copolymer has a renewable carbon content from about 5% to about 100% as determined by ASTM D6866.

[0010] For the sake of clarity, the "bio-based EVA" of the present invention may be also referred as "Green EVA".

[0011] In some embodiments, the ethylene-vinyl acetate (EVA) copolymer comprises a vinyl acetate (VA) content ranging from 5 wt.% to 49.9 wt.%. The VA content may vary from a lower limit selected from 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 wt.% to an upper limit selected from 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, or 49.9 wt.%, based on the total weight of the copolymer. Any lower limit may be combined with any upper limit to define a suitable range. The selection of VA content may be tailored to meet specific mechanical, thermal, or processing requirements of the intended application.

[0012] In some embodiments, the copolymer has a density from about 0.93 to about 0.97 g / cm3.

[0013] In some embodiments, the copolymer has a melt flow index (190 °C / 2.16 kg) ranging from about 0.1 to about 1000 g / 10 min, preferably from 0.1 to about 400 g / 10 min.

[0014] In some embodiments, the copolymer has a Shore A hardness is from about 40 to about 95.

[0015] In some embodiments, the copolymer has a melting point from about 60 °C to about 95 °C.

[0016] The compositions optionally include one or more additives and / or additional polymers to tailor properties for foams, films, adhesives, construction, packaging, footwear and other applications.

[0017] The ethylene and / or vinyl acetate may be entirely or partially obtained from renewable sources. In some embodiments, the EVA resin comprises ethyleneobtained from renewable sources and vinyl acetate obtained from traditional sources. In other embodiments, the EVA resin comprises ethylene and vinyl acetate both obtained from renewable sources.

[0018] The EVA polymer may exhibit thermoplastic behavior and be processable by conventional techniques including extrusion, injection molding, compression molding, calendaring, blow molding, foaming, rotomolding, and film casting.

[0019] The EVA polymer may be amorphous to semi-crystalline depending on VA content.

[0020] The bio-based EVA compositions disclosed herein are designed as drop-in replacements for conventional fossil-derived EVA. As such, they are formulated to be compatible with existing processing equipment and conditions, enabling seamless substitution without requiring modifications to manufacturing setups or tooling.Renewable Feedstocks and Monomers

[0021] Renewable ethylene may be obtained by fermenting a renewable source of carbon (e.g., sugarcane, corn, beet, agricultural residues, cellulose) to produce ethanol, optionally purifying the ethanol to reduce higher alcohols, and dehydrating the ethanol in the presence of a catalyst at a temperature typically above 300 °C to yield ethylene, followed by purification to remove higher alkenes when present. Renewable vinyl acetate may be produced by oxidizing renewable ethanol to acetic acid and reacting the bio-based ethylene with the acetic acid under acyloxylation conditions to form vinyl acetate, followed by isolation and optional purification.Exemplary Integrated Route to Bio-based Vinyl Acetate

[0022] In an exemplary route, a first portion of fermented alcohol is dehydrated in a first reactor to produce ethylene (optionally after removal of higher alcohols and / or higher alkenes), and a second portion is oxidized in a second reactor to produce acetic acid. The ethylene and acetic acid streams are combined in a third reactor and reacted to form vinyl acetate, which is isolated and optionally purified.Polymerization

[0023] The EVA copolymer may be produced via high-pressure free-radical polymerization in tubular and / or autoclave reactors using organic peroxide initiators. Initiators are not retained as functional additives in the finished pellets. The resulting resin is collected, pelletized, and may be compounded as described below.Blends and Additives

[0024] The bio-based EVA may be formulated alone or in blends with one or more other type of polymers.

[0025] In certain embodiments, the bio-based ethylene-vinyl acetate (EVA) may be blended with one or more other type of polymers including polyolefins (e.g., polyethylene, polypropylene, ethylene-alpha-olefin copolymers), functional polyolefins (e.g., ethylene-maleic anhydride, ethylene-acrylic acid, ethylene-methyl acrylate), polyesters (e.g., PET, PBT, PLA), biopolymers (e.g., PHA family, starch, cellulose derivatives), rubbers and elastomers (e.g., EPDM, EPM, NR, SBR, BR, NBR, CR, HR, HNBR, SBS, SEBS, SIS, TPU, silicones, fluoroelastomers), and engineering thermoplastics (e.g., ABS, HIPS, PC, PA, PS, SAN). In some embodiments, the bio-based ethylene-vinyl acetate (EVA) may be blended with one or more polyethylenes including ULDPE, VLDPE, LLDPE, LDPE, MDPE, HDPE, and other ethylene-based polymers, wherein the polyethylenes may be obtained from renewable or fossil sources. The polyethylene may be obtained from commonly known polymerization processes using initiators (e.g. high pressure processes) or catalysts (e.g. metallocene, Ziegler-Natta, Chromium, and others).

[0026] The proportion of other type of polymers in the blend may range from a lower limit selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44,45, 46, 47, 48, 49, up to 50 wt.% to an upper limit selected from 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,72, 73, 74, 75, 76, 77, 78, 79,80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 up to 99 wt.%, based on the total weight of bio-based EVA and the other type of polymers. Any lower limit may be combined with any upper limit to define a suitable range. The blend may be homogeneous or heterogeneous, and may be processed using conventional polymer blending techniques, including melt mixing, extrusion, or reactive blending.

[0027] In certain embodiments, the bio-based ethylene-vinyl acetate (EVA) may be blended with fossil-based EVA. Such blends may be particularly advantageous when the commercially available bio-based EVA does not meet specific performance requirements for a given application. In these cases, the incorporation of fossil-based EVA may compensate for property gaps, enabling the resulting EVA composition to achieve a desirable balance of mechanical, thermal, or processing properties. The proportion of fossil-based EVA in the blend may range from a lower limit selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, up to 50 wt.% to an upper limit selected from 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 up to 99 wt.%, based on thetotal weight of bio-based EVA and fossil-based EVA. Any lower limit may be combined with any upper limit to define a suitable range. The blend may be homogeneous or heterogeneous, and may be processed using conventional polymer blending techniques, including melt mixing, extrusion, or reactive blending.

[0028] The Green EVA resin may be compounded with a variety of additives to tailor its performance for specific applications. These may include:• Peroxide curing agents: organic peroxides capable of initiating crosslinking (e.g., dicumyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane), typically in concentrations from 0.01 to 5 wt%.• Coagents for crosslinking: triallyl isocyanurate (TAIC), triallyl cyanurate (TAC), trimethylolpropane trimethacrylate (TRIM), etc., typically in levels from 0.01 to 2 phr.• Foaming agents: o Chemical blowing agents: azodicarbonamide (ADC), sodium bicarbonate, citric acid etc; o Physical blowing agents: supercritical CO2or N2; o Solid or liquid forms may be incorporated as powders or masterbatches.• Plasticizers and processing aids: paraffinic oils, fatty acid esters, glycols, phthalate alternatives.• Flame retardants: aluminum trihydrate (ATH), magnesium hydroxide, halogen- free systems.• Stabilizers and antioxidants: phenolic antioxidants, phosphites, HALS (hindered amine light stabilizers), UV absorbers, IR reflectors.• Colorants and visual modifiers: organic / inorganic pigments, titanium dioxide, fluorescent dyes.• Lubricants and mold-release agents: metallic stearates (e.g., zinc stearate), waxes, erucamides.• Compatibilizers and coupling agents: maleic anhydride grafted polymers, silanes.• Reinforcing and functional fillers: o Mineral fillers: calcium carbonate, talc, kaolin, mica, feldspar, silica (amorphous, precipitated, or fumed) o Nanomaterials: nano-silica, nano-clays, zinc oxide, titanium dioxide o Recycled EVA: derived from regrind or post-industrial scrap

[0029] These additives may be introduced through direct blending, masterbatching, or other compounding techniques such as twin-screw extrusion or internal mixing.Applications

[0030] The Green EVA of the present invention may be used in several applications which includes but are not limited to:1. Foams

[0031] Green EVA is suitable to produce microcellular crosslinked foams. The Table 1 shows some examples of foam applications, properties characteristics and typical properties for foam applications:Table 1. Foam applications2. Packaging and Films

[0032] The Green EVA of the present invention may be applicable in the manufacture of transparent or opaque films. Table 2 presents some possibilities of application and typical properties.Table 2. Packaging and films applications3. Automotive and Construction

[0033] The Green EVA of the present invention may be applicable in automotive and construction fields. Table 3 presents some possibilities of application and typical properties.Table 3. Automotive and Construction applications

[0035] Table 5 presents some typical property ranges:Table 5. Typical property ranges of EVA for adhesives and compounds applications5. Other Applications

[0036] The Green EVA resin can be used in a wide variety of molded or extruded articles across multiple industries, including but not limited to footwear, sports goods, household items, industrial components, fragranced products, toys, and office supplies.

[0037] Footwear: being suitable for compact and expanded soles; insoles and midsoles (compression or injection molded); unisoles and monoblock sandals; flip-flop sandals; full EVA shoes.

[0038] Sports Goods: applicable for yoga blocks, gym steps, training mats; balls (e.g., EVA soccer balls, soft balls); weightlifting gloves and grips; shin and joint protectors; finger protectors, toe separators; swimming floats, leg floats, kickboards.

[0039] Household and Furniture: used in decorative mats, carpets, and foam sheets; cushions, seats, and protective covers; sponges (cleaning or cosmetic); glass edge profiles and sealing trims; stationery and decorative panels; educational items (e.g., EVA alphabets, shapes).

[0040] Fragranced Items: Green EVA can incorporate fragrance additives for long-lasting diffusion in: car air fresheners and scented gadgets; perfumed EVA sheets and decorative items; fragrance carriers for ambient diffusion; promotional items with embedded scents.

[0041] Injection Molding and Miscellaneous: including Soft-touch articles (e.g., handles, grips, wearables); Flexible closures and bottles; Toys and educational games (molded EVA toys, blocks, puzzles); Orthopedic items (e.g., supports, heel cups); Office and advertising materials (e.g., EVA displays, logos).

[0042] Other applications includes wire, cables and solar panel encapsulants.

[0043] For the mentioned applications, green EVA may exhibit the following Typical Properties Across These Applications: Good surface finish and soft touch; Flexibility and fatigue resistance; Lightweight and buoyant when expanded; Odorless and nontoxic when properly formulated; UV and aging resistance (with stabilization); Colorability, scentability, and custom moldability.Process of Green and Fossil-based EVA

[0044] As occurs in fossil-based EVA, Green EVA may be processed by a variety of techniques, including but not limited to:• Molding: injection molding; extrusion molding; extrusion blow-molding; compression molding; injection molding; injection blow-molding; rotational molding; and ISBM (Injection Stretched Blow-Molding).• Extrusion: general extrusion; blown film extrusion; cast film extrusion; and coextrusion.• Foaming thermoforming; 3D printing; rotomolding; pultrusion, double expansion process; and others to produce manufactured articles.Environmental Benefits of Green EVA

[0045] Reduction of carbon footprint, due to the partial or total substitution of fossilbased feedstocks by renewable raw materials such as sugarcane-derived ethanol, contributing to the mitigation of greenhouse gas emissions throughout the product life cycle. Biogenic CO2emissions upon incineration at end-of-life, meaning that the carbon released during energy recovery originates from renewable, short-cycle biomass, not from fossil carbon stocks. Drop-in compatibility with existing industrial equipment and processes designed for conventional fossil-based EVA, facilitating adoption without requiring process modifications or new infrastructure.Braskem's Green EVA Products

[0046] As of 2025, Braskem has two green EVA products: SVT2180 and SVT2145R. Production for both products started in the first semester of 2018.

[0047] SVT2180 is a copolymer of renewable ethylene with vinyl acetate mainly used to produce crosslinked foam sheets and other parts. It is a product with easy processability and high compatibility with mineral fillers, and thermoplastic and elastomeric resins. Other important characteristics are elasticity, flexibility, excellent stress cracking resistance (ESCR), chemical resistance, and low temperature strength. The exclusive morphologic characteristics give an outstanding crosslinkability. The components produced with SVT2180 have the following properties: low weight,resistance to deformation, low shrink, high capacity of sticking and color retention. The minimum biobased carbon content of this grade is 80%, determined according to ASTM D6866.

[0048] And SVT2145R is a resin based on ethylene-vinyl acetate copolymer, is easily crosslinkable and also shows high compatibility with other thermoplastics resins, inorganic fillers and pigments. Compositions with SVT2145R show high flexibility and fatigue resistance. Cross-linked compound has outstanding abrasion resistance and has a high friction coefficient. The minimum biobased carbon content of this grade is 45%, determined according to ASTM D6866.

[0049] Table 6 shows Braskem patents related to the Green EVA.Table 6. Braskem's Green EVA Patents

Claims

Claims1. Bio-based EVA composition comprising a copolymer of ethylene and vinyl acetate having from about 5 wt% to about 49.9 wt% of vinyl acetate comonomer and a melt flow index at 190 °C / 2.16 kg from about 0.1 to about 1000 g / 10 min, wherein the copolymer has a renewable carbon content from about 5% to about 100% as determined by ASTM D6866.

2. The composition claim 1, wherein the ethylene, the vinyl acetate or both (co)monomers are obtained partially or entirely from renewable sources.

3. The composition of any of claims 1 or 2, wherein the bio-based EVA has a density from about 0.93 to about 0.97 g / cm3.

4. The composition of any of claims 1 to 3, wherein the bio-based EVA has a Shore A hardness from about 40 to about 955. The composition of any of claims 1 to 4, wherein the bio-based EVA has a melting point from about 60 °C to about 95 °C.

6. The composition of any of claims 1 to 5, wherein at least a portion of the ethylene is obtained by dehydration of ethanol derived from biomass selected from sugarcane, corn, beet, agricultural residues, and cellulose.

7. The composition of any of claims 1 to 6, wherein at least a portion of the vinyl acetate is obtained by (i) oxidizing biomass-derived ethanol to acetic acid and (ii) reacting bio-based ethylene with the acetic acid to form vinyl acetate.

8. The composition of any of claims 1 to 7, further comprising one or more additives selected from peroxide curing agents, coagents for crosslinking, foaming agents, plasticizers, processing aids, flame retardants, stabilizers, antioxidants, colorants, visual modifiers, lubricants, mold-release agents, compatibilizers, coupling agents, reinforcing, functional fillers and combinations thereof.

9. The composition of any of claims 1 to 8, wherein the composition is further processed by conventional techniques including extrusion, injection molding, compression molding, calendaring, blow molding, roto molding, foaming and film casting.

10. A method of making the composition of any of claims 1 or 8, comprising polymerizing ethylene and vinyl acetate under high-pressure free-radical conditions in a tubular and / or autoclave reactor, and optionally compounding the EVA resin with one or more additives selected from coagents, foaming agents, stabilizers, colorants, lubricants, flame retardants, fillers, and compatibilizers.

11. Blends comprising the composition of any of claims 1 or 8 and one or more other type of polymers selected from polyolefins (e.g., polyethylene, polypropylene, ethylene- alpha-olefin copolymers), functional polyolefins (e.g., ethylene-maleic anhydride, ethylene-acrylic acid, ethylene-methyl acrylate), polyesters (e.g., PET, PBT, PLA), biopolymers (e.g., PHA family, starch, cellulose derivatives), rubbers and elastomers (e.g., EPDM, EPM, NR, SBR, BR, NBR, CR, HR, HNBR, SBS, SEBS, SIS, TPU, silicones, fluoroelastomers), engineering thermoplastics (e.g., ABS, HIPS, PC, PA, PS, SAN) and combinations thereof.

12. Blends according to claim 11 wherein the polyethylene is selected from ULDPE, VLDPE, LLDPE, LDPE, MDPE, HDPE, other ethylene-based polymers and combinations thereof, wherein the polyethylene may be obtained from renewable or fossil sources.

13. Blends according to any of claims 11 or 12 wherein the proportion of other type of polymers in the blend may range from a lower limit selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, up to 50 wt.% to an upper limit selected from 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 up to 99 wt.%, based on the total weight of bio-based EVA and the other type of polymers wherein any lower limit may be combined with any upper limit to define a suitable range.

14. Blends comprising the composition of any of claims 1 or 8 and fossil-based EVA.

15. Blends according to claim 14 wherein the proportion of fossil-based EVA in the blend may range from a lower limit selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, up to 50 wt.% to an upper limit selected from 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 up to 99 wt.%, based on the total weight of bio-based EVA and fossil-based EVA wherein any lower limit may be combined with any upper limit to define a suitable range.

16. An article comprising the composition of any of claims 1 or 8, the article selected from foams, packaging, films, sheets, laminates, adhesive, automotive articles, construction articles, footwear components, industrial mats, mattresses, sports protection gear, gaskets, seals, flooring, household, toys, caps, closures, furniture, wires, cables, solar panel encapsulants and fragranced Items.