Formulation and method for the production of flame retardant polymer and products obtained from such formulation

Abstract

A thermoplastic polymeric material containing at least one thermoplastic polymer and at least one additive adapted to impart anti-flame properties to the polymeric material is described. The thermoplastic polymer is a biodegradable and / or preferably compostable polymer selected from thermoplastic starch polymers (TPS), polyvinyl alcohol (PVA) and mixtures thereof. On the other hand, the anti-flame additive is selected from halogenated hydrocarbons, preferably brominated hydrocarbons, more preferably brominated aromatic hydrocarbons, antimony trioxide and mixtures of antimony trioxide and brominated aromatic hydrocarbons.

Description

[0001] "FORMULATION AND METHOD FOR THE PRODUCTION OF FLAME

[0002] RETARDANT POLYMER AND PRODUCTS OBTAINED FROM SUCH

[0003] FORMULATION"

[0004] The present invention relates to the field of producing polymers provided with anti-flame or flame-retardant properties. In more detail, the present invention concerns the manufacture of polymer products provided with flame retardant properties and in particular containers, plastic films for packaging and various articles requiring this characteristic.

[0005] Recycling plastics has now become a must for manufacturers of plastic articles from packaging to containers, copiers, computers and automotive components. Indeed, current legislation imposes increasingly stringent limits on plastic materials aimed at recycling or reusing plastic products.

[0006] Since there are so many different types of plastics used, products must be separated and sorted to be processed as secondary raw materials, for example polyolefins must be separated from polyamides or polyesters in order to be properly recycled while preserving the mechanical characteristics of the source material as much as possible so that they can be used again in the source application, thus realizing the required circular economy. A typical method of recycling plastic materials is to be reduced again to granules or flakes of material ready to be reused; such processing requires hot treatment of the plastic to be recycled, such as by grinding or fragmentation in mills, and extrusion.

[0007] A further problem for the recycling of plastic materials is the presence of additives, particularly anti-flame additives, which are the most problematic and generate a number of critical issues during the recycling steps.

[0008] Plastic articles that contain outlawed anti-flame products must be treated as special waste; however, articles made of plastics containing the other types of anti-flame additives have problems due to the reactions of the anti-flame additives during recycling processes with extrusion or hot milling of said plastics.

[0009] Plastics with anti-flame additives containing halides, particularly those based on brominated organic molecules, typically generate bromine, free radicals and hydrobromic acid during a recycling process by heating, such as in the extrusion steps for their conversion into pellets, resulting in damage to extruders, yellowing and degradation of the plastic material and consequent increase in their Melt Flow Index.

[0010] Therefore, the problem of recycling plastics containing anti-flame additives, i.e., additives that impart flame retardant properties, arises.

[0011] Object of the present invention is to solve the problems discussed above and provide a formulation of thermoplastic material with anti-flame additives that is easily recyclable or anyhow disposable. Other objects are to provide a process for preparing such a polymeric material and supplying the products made from such a polymeric material, in particular reels of flame retardant film, for example, for packaging flammable materials and products, such as pyrotechnic products, construction products and bodywork products.

[0012] These objects are achieved by means of the present invention, which relates to a thermoplastic material according to claim 1, a product according to claim 6 or 7, a process according to claim 8, and the use of particular additives according to claim 13 or 14.

[0013] Preferential aspects are subject matter of the dependent claims.

[0014] In a preferential aspect, the invention relates to a thermoplastic polymeric material, wherein said thermoplastic polymer is TPS, said anti-flame additive is a mixture of brominated aromatic hydrocarbons and antimony trioxide, said additive being present in an amount between 15% and 26% by weight to the total weight of said polymeric material and wherein said carrier for said anti-flame additive is selected from EVA and Pbat.

[0015] Another aspect of the invention is the use of an anti-flame brominated aromatic additive for the production of thermoplastic starch polymers having flame resistance.

[0016] Another aspect of the invention is the use of thermoplastic starch polymers for the production of thermoplastic polymers and, in particular, thermoplastic polymeric films having flame resistance, wherein said anti-flame additive is a mixture of brominated aromatic hydrocarbons and antimony tri oxide, said additive being present in an amount between 15% and 26% by weight to the total weight of said polymeric material and wherein said carrier for said anti-flame additive is selected from EVA and Pbat.

[0017] The thermoplastic material of the invention contains at least one additive with anti-flame properties; said thermoplastic material is selected from bioplastics based on thermoplastic starch polymeric material (TPS) and polyvinyl alcohol (PVA) or mixtures thereof. Preferably, the material is a TPS of the type suitable for extrusion or injection molding. A preferred class of polymers whose biodegradability is particularly effective is that of the thermoplastic starch polymers (TPS), i.e., polymers based on starch components, particularly amylose and amylopectin, with the addition of complexing agents, additives and possibly plasticizers. Such polymers are known in the art and are commercially available. An example of a polymeric material of this type is Mater-Bi ®, for example, Mater-Bi® EF05B, marketed by Novamont. In the following, the term starch polymer or TPS will be used for brevity to define the entire class of starch-based polymers, additives and other components without intending to restrict its scope to the Mater-Bi product alone.

[0018] The term "thermoplastic" is used to refer to a polymeric material that can be processed under the action of heat and, in particular, a material that can be processed by what is known as bubble extrusion or flat-head extrusion or injection molding or thermoforming.

[0019] The term "biodegradable" means a material that is decomposable under the action of bacteria or other microorganisms, under certain conditions of temperature, humidity and oxygen concentration, into water, carbon dioxide and biomass (compost).

[0020] For the purpose of this description, the term "compostable" means a material that complies with UNI EN 13432 standard. In this regard, the UNI EN 13432 standard specifically requires that the biodegradability (aerobic biodegradation) of the material be > 90%.

[0021] According to a preferred embodiment, the additive for the thermoplastic material comprises or consists of a brominated hydrocarbon, preferably a brominated aromatic hydrocarbon. Brominated aromatic hydrocarbons with anti-flame properties (ABFRs) are known in the art per se and are for example represented by polybrominated diphenyl ethers (PBDEs), tetrabromobisphenol A (TBBPA) and polybrominated biphenyls (PBBs).

[0022] In a preferred embodiment, the anti-flame additive also contains antimony trioxide SbzOs in addition to one or more brominated aromatic hydrocarbons. The weight ratio of brominated aromatic hydrocarbons to antimony trioxide is preferably in the range between 3: 1 and 4: 1. Mixtures of this type are commercially available.

[0023] Preferably, the additives are dispersed in ethylene vinyl acetate (EVA) or polybutyrate- adipate-terephthalate (Pbat) and are used in a physical form known in the art, for example, in the form of masterbatch granules. This composition with EVA or Pbat was found to be easily incorporated into thermoplastic starch polymers at their processing temperature, with no or very low production of free halogens. Masterbatches of this type are commercially available and are used in a known way to impart flame resistance characteristics to polyolefin thermoplastic polymers, such as high or low density polypropylene and polyethylene, polyamides, polyesters of various types, ABS and the like.

[0024] The use of such masterbatches in thermoplastic starch polymer matrices, or in PLA matrices, has not been proposed to date. The Applicant surprisingly found that the abovediscussed anti-flame additives, particularly those dispersed in EVA and / or Pbat, can be added to known TPS and PLA polymers without problems.

[0025] Typically, in the masterbatch material, the amount of additives (referred to as anti-flame agents) is in the range of 40%-90% by weight, for example 50%-90%, to the total polymer matrix (for example EVA and / or Pbat) and additive. Preferably, in the case of EVA, anti-flame additives are present in an amount by weight between 50 and 70% by weight, more preferably 60% by weight, to the total weight of the masterbatch formulation; in the case of Pbat, antiflame additives are preferably present in an amount by weight between 70 and 90% by weight, more preferably 80% by weight, to the total weight of the masterbatch formulation.

[0026] The Applicant surprisingly found that halogenated aromatic hydrocarbons, preferably brominated aromatic hydrocarbons, more preferably a mixture of brominated aromatic hydrocarbons and antimony trioxide dispersed in EVA and / or Pbat polymer matrix to the above extent of 40%-90% by weight, preferably 50%-90% by weight, more preferably 50%-85% by weight to the masterbatch formulation, are capable of being mixed with thermoplastic starch polymers or with PLA polymers or with mixtures of thermoplastic starch polymers and PLA and of imparting anti-flame characteristics to the same without compromising the mechanical and biodegradability characteristics of the TPS polymers in question.

[0027] The anti-flame, i.e., fireproof, characteristics of the biodegradable polymer according to the present invention are verified by using UL 94 standard, i.e., the "Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances". The test according to that standard is to measure the time that the vertically mounted plastic material specimen having thickness of 3.2 mm continues to bum after it has been hit by the flame of a Bunsen for 10 seconds.

[0028] The amount of masterbatch, that is, the product comprising polymer matrix and antiflame agent, added to the TPS polymer is generally in the range between 10% by weight and 40% by weight to the total weight of the formulation comprising thermoplastic starch polymer; preferably this range is between 20% and 35% by weight. As discussed above, the amount of active anti-flame product (also called flame retardant) in the masterbatch granules is in the range between 40% and 90% by weight, preferably between 40% and 60% by weight to the total weight of the masterbatch product.

[0029] In other words, the amount of anti-flame additive present in the final mixture, i.e., for example, in the extruded film, is in the range between 0.4% by weight and 36% by weight, preferably between 4% and 36%, more preferably between 8% and 30%, for example, 29.75%, even more preferably between 15% and 24% by weight to the total weight of the additivated polymeric product. A preferred range is between 18% and 22% by weight.

[0030] The invention also has the advantage that the TPS polymer has a low melting point of Mater-Bi / TPS (about 100-145 °C) compared to PP, PA or HDPE (about 110-160 °C) and is therefore easily processable at lower temperatures, so that the development of bromine or halogens in their various forms is greatly reduced during said processing.

[0031] Furthermore, you can compost the product even if there are antimony trioxide additive or brominated hydrocarbons. In soil, antimony trioxide has moderate mobility and is found adsorbed to clays and hydroxides or bound to organic matter to form complexes. Generally, the occurrence in soils ranges from 0.05 to 4.0 mg / kg with an average value of 1 mg / kg.

[0032] The properties of the thermoplastic starch polymer are selected according to the use of the end product; advantageously, TPS polymer can be used to replace traditionally used materials such as polypropylene and polyethylene.

[0033] Examples of products using the TPS polymer of the invention are containers and packaging films such as those for pyrotechnic products, flammable products, in the field of bodywork products and in the field of construction, such as electric circuit boxes and the like.

[0034] The invention will now be described in more detail with reference to the following nonlimiting examples.

[0035] Example 1 - Preparation of a TPS with flame retardant properties.

[0036] To 83.5 kg of a TPS compostable polymer, specifically Novamont SPA's Mater-Bi® EF05B, increasing amounts of 12% to 28% by weight of anti-flame additive for masterbatch containing 60% by weight of active anti-flame ingredients of anti-flame additive composed of a mixture of brominated hydrocarbons and antimony trioxide were added during extrusion. The masterbatch used was MB FR PBAT 01479 commercially available from MA Plastic Engineering SRL Masterbatch & Special Compounds. It was verified that, with the addition of 20% and preferably 30% by weight of a 60% masterbatch of anti-flame additive (flame retardant) comprising brominated aromatic hydrocarbons and Antimony Trioxide, i.e., an amount of anti-flame additive in the range between 12% and 18% by weight of additive to the total final formulation containing TPS and additives, a self-extinguishing characteristic of the film was achieved that fully complied with the current regulations for the packaging of pyrotechnic articles.

[0037] The resulting product was bubble-extruded to form a tubular film and in turn cut into single sheets for product packaging. The resulting film had mechanical characteristics comparable to those of the same polymer without anti-flame filler and capable of meeting the specifications required for its end use in packaging of flammable products, particularly pyrotechnic products.

[0038] The fireproof characteristics, in detail the self-extinguishing characteristics, of the polymer extruded as a film after each addition were verified by using UL 94 standard. The test according to this standard is to measure the time that the plastic material specimen, which is vertically mounted and has a thickness of 3.2 mm, continues to burn after it has been hit by the flame of a Bunsen for 10 s. In this standard, the material is classified according to when the flame is extinguished, within 10 or 30 seconds without or with dripping of burning material. The product of the example was found to have V-l rating, with flame extinguishing time of 30 seconds without dripping of burning material.

[0039] Example 2 - Preparation of a TPS with flame retardant properties.

[0040] To 83.5 kg of a TPS compostable polymer, specifically Novamont SPA's Mater-Bi® EF05B, amounts equal to 26% and 30% by weight of masterbatch containing 80% by weight of anti-flame additive composed of a mixture of brominated hydrocarbons and antimony trioxide were added in separate tests during extrusion. The masterbatch used included ethylene vinyl acetate as the matrix-carrier and is commercially available as MB FR EVA 01040 from MA Plastic Engineering SRL Masterbatch & Special Compounds. Thus, the amount of anti-flame additive was 20.8% and 24% by weight of additive to the total final formulation containing TPS and additives, and a self-extinguishing characteristic of the film was achieved that fully meets the current regulations for the packaging of pyrotechnic articles. The resulting product was bubble-extruded to form a tubular fdm and in turn cut into single sheets for product packaging. The resulting film had mechanical characteristics comparable to those of the same polymer without anti-flame filler and capable of meeting the specifications required for its end use in packaging of flammable products, particularly pyrotechnic products.

[0041] The anti-flame, i.e. self-extinguishing, characteristics of the polymer extruded as a film after each addition were verified by using the UL 94 standard described above. The product of the two formulations was found to have V-0 rating, with flame extinguishing time of 10 seconds without dripping of burning material (glowing material).

[0042] The invention also relates to a process for the production of a polymeric material with anti-flame properties, comprising the steps of adding a biodegradable and / or compostable thermoplastic polymer, preferably selected from thermoplastic starch polymers (TPS) and polyvinyl alcohol (PVA) with a masterbatch containing an anti-flame additive comprising or consisting of brominated aromatic hydrocarbons and Antimony trioxide, and processing said polymeric material into a product. Processing is done in a way known in the art, preferably by extrusion, more preferably by bubble extrusion to form a film.

[0043] The film is typically used as a packaging product with anti-flame characteristics, particularly flame retardant characteristics. In an embodiment the product packed, that is, packaged, with the film of the invention is a pyrotechnic product.

[0044] In other embodiments the product is obtained, for example, by injection molding and the fields of application of the product as a film or molded (or extruded) comprise, for example, construction and automotive products, particularly bodywork and coachwork products.

[0045] According to a preferred embodiment, the above mentioned masterbatch contains a polymer matrix and an amount of anti-flame additive in the range between 40% and 90%, preferably between 50% and 90%, more preferably between 60% and 80%, by weight to the total weight of the masterbatch formulation, said polymer matrix being preferably selected from ethyl vinyl alcohol (EVA) and polybutyrate-adipate-terephthalate (Pbat) and mixtures thereof.

[0046] In an embodiment, the amount of this masterbatch added to said polymer is in the range between 10% and 40% by weight, preferably between 20% and 35% by weight, to the total weight of the polymeric material. In another aspect, the invention relates to a reel of packaging film wherein said film is formed by a thermoplastic polymeric material according to the invention, as described above.

[0047] In a further aspect, the invention relates to the use of brominated aromatic hydrocarbons and antimony trioxide and mixtures thereof as an anti-flame additive for the production of thermoplastic polymeric material having flame resistance selected from thermoplastic starch polymers (TPS) and polyvinyl alcohol (PVA).

Claims

CLAIMS1. Thermoplastic polymeric material containing at least one thermoplastic polymer and at least one additive adapted to impart anti-flame properties to said polymeric material, characterized in that said thermoplastic polymer is a biodegradable and / or compostable polymer selected from thermoplastic starch polymers (TPS), polyvinyl alcohol (PVA) and mixtures thereof, and in that said anti-flame additive is selected from brominated hydrocarbons, more preferably brominated aromatic hydrocarbons, antimony trioxide and mixtures of antimony trioxide and brominated aromatic hydrocarbons.

2. Thermoplastic polymeric material according to claim 1, wherein said thermoplastic material further comprises a carrier polymer for said anti-flame additive, said carrier polymer being preferably selected from ethylene vinyl acetate (EVA) and polybutyrate- adipate-terephthalate (Pbat) or mixtures thereof.

3. Thermoplastic polymeric material according to claim 1 or 2, wherein the amount of anti-flame additive is in the range between 0.4% by weight and 40% by weight, preferably between 4% and 36%, more preferably between 8% and 30% by weight to the total weight of the additivated polymeric product.

4. Thermoplastic polymeric material according to claim 3, wherein said additive adapted to impart anti-flame properties is present in an amount between 10% and 30%, preferably between 15% and 26% by weight to the weight of said polymeric material.

5. Thermoplastic polymeric material according to claim 3 or 4, wherein said thermoplastic polymer is TPS, said anti-flame additive is a mixture of brominated aromatic hydrocarbons and antimony tri oxide, said additive being present in an amount between 15% and 26% by weight to the total weight of said polymeric material and wherein said carrier for said anti-flame additive is selected from EVA and Pbat.

6. Thermoplastic polymeric material according to one of the preceding claims, in the form of packaging film.

7. Reel or sheet of packaging film, wherein said film is formed from a thermoplastic polymeric material according to claim 5.

8. Process for the production of a polymeric material with anti-flame properties, characterized in that it comprises the steps of: supplying a biodegradable and / or compostable thermoplastic polymer, preferably selected from thermoplastic starch polymers (TPS), polyvinylalcohol (PVA) and mixtures thereof; adding to said biodegradable and / or compostable polymer a masterbatch containing an anti-flame additive; processing, preferably by extrusion, said polymeric material into a product, more preferably by extrusion to form a film or sheet.

9. Process according to claim 8, wherein said masterbatch contains a polymer matrix having carrier function and an amount of anti-flame additive in the range between 40% and 90% by weight to the total weight of the masterbatch formulation, said polymer matrix being preferably selected from ethylene vinyl acetate (EVA) and polybutyrate-adipate- terephthalate (Pbat) and mixtures thereof, said anti-flame additive being selected from halogenated hydrocarbons, preferably brominated hydrocarbons, more preferably brominated aromatic hydrocarbons and antimony trioxide and mixtures of antimony trioxide and brominated aromatic hydrocarbons.

10. Process according to one of claims 8 or 9, wherein the amount of masterbatch added to said polymer is in the range between 10% and 40% by weight to the total weight of the polymeric material, said masterbatch comprising an amount of anti-flame additive in the range between 40% and 85% by weight to the total weight of the masterbatch.

11. Process according to one of the preceding claims, wherein said anti -flame additive consists of a mixture of brominated aromatic hydrocarbons and antimony trihydroxide.

12. Process according to claim 11, wherein said thermoplastic polymer is TPS, said anti-flame additive is present in an amount between 15% and 26% by weight to the total weight of said polymeric material and wherein said polymer matrix having carrier function for said anti-flame additive is selected from EVA and Pbat.

13. Use of mixtures of brominated aromatic hydrocarbons and antimony tri oxide as anti-flame additive for the production of thermoplastic polymeric material having flame resistance, which is selected from thermoplastic starch polymers (TPS) and polyvinyl alcohol (PVA).

14. Use of thermoplastic starch polymers (TPS) for the production of thermoplastic polymeric material, in particular of thermoplastic polymeric films having flame resistance, wherein said anti-flame additive is a mixture of brominated aromatic hydrocarbons and antimony tri oxide, said additive being present in an amount between 15% and 26% by weight to the total weight of said polymeric material and wherein said carrier for said anti-flame additive is selected from EVA and Pbat.