Halogen-free flame retardant composition, composite panel, and method of fabricating the composite panel

Abstract

This disclosure provides an embodiment of a halogen-free flame retardant composition comprising one or more polyolefin copolymers having a melt flow index of 350 g / 10 min to 1000 g / 10 min as measured at 190°C and 2.16 kg, wherein the one or more polyolefin copolymers include maleic anhydride-grafted polyolefins, ethylene-vinyl acetate copolymers, or both; and an inorganic filler comprising more than 83% by weight of the total weight of the halogen-free flame retardant composition.

Description

[Technical Field] The embodiments described herein are generally related to halogen-free flame retardant materials, and more specifically to halogen-free flame retardant materials used in the core layer of aluminum composite panels. [Previous Technology] The aluminum composite panel is a rigid composite design, made of a polymer core and bonded to the aluminum surface sheet with an adhesive bonding layer. Aluminum composite panels are commonly used in infrastructure facade systems, visual displays, and transportation. For example, aluminum composite panels can be used in exposed facade systems of high-rise buildings. [Summary of the Invention] Following a recent fire in a high-rise building, stricter fire safety regulations have been implemented for building facade systems. Aluminum composite panels, their fire resistance, and fuel load can be important to the safety of facade systems. Testing standards are defined by the fire resistance rating of the aluminum composite panel core material. This rating can be determined based on the core material's total heat of combustion (also known as calorific value or superheat; PCS), fire rate of fire (FIGRA), flammability, and / or total heat release (THR). In some incidents, the presence of a non-flame-retardant polymer composite core may allow fire to spread to the facade system during a fire. Today, aluminum composite panel manufacturers supply flame-retardant panels specifically designed for facade systems, conforming to Euroclass B or the more stringent Euroclass A2 rating, which specifies the flammability of the restricted core material. With the production and global sales of these panels, Euroclass A2 has become a global requirement. Currently, core materials meeting Euroclass A2 fire safety standards are typically processed by sintering a slurry from inorganic non-combustible components in a water-based binder system on a dual-frequency press. However, the sintering method can be relatively slow and expensive, and the sheets can be relatively difficult to process. Additionally, sintered core materials with high filler content often exhibit poor mechanical strength. Furthermore, the sintering process may require specific production equipment. On the other hand, sheet extrusion lines can be used to produce conventional non-Euroclass A2 composite panels. However, for polyolefin-based formulations with an inorganic filler content exceeding 83% by weight, extrusion or direct extrusion is difficult or impossible. In such cases, direct extrusion combines the composite process with the final shaping into flat sheets in a single processing step. Therefore, there is a need for compositions that can be extruded in the production of Euroclass A2 core materials for aluminum composite panels. Embodiments of this disclosure meet these needs by providing compositions comprising one or more polyolefin copolymers having a melt flow index of 350 g / 10 min to 1000 g / 10 min, measured at 190°C and 2.16 kg; and greater than 83% by weight of inorganic filler based on the total weight of the halogen-free flame retardant composition. The disclosed composition, containing more than 83% by weight of inorganic filler, achieves Euroclass A2, meaning that the PCS of the formulation according to EN ISO 1716 is less than 3 MJ / kg. At filler contents of 83% by weight or higher, the polymer backbone of the disclosed composition allows for extrudable compositions that can be used as a core layer in economical and efficient manufacturing methods for aluminum composite panels. Furthermore, the embodiments of this disclosure allow for improved mechanical strength and flexibility compared to conventional sintered Euroclass A2 compositions. According to at least one embodiment of this disclosure, a halogen-free flame retardant composition is provided. Examples of the halogen-free flame retardant composition may include one or more polyolefin copolymers with a melt flow index of 350 g / 10 min to 1000 g / 10 min, measured at 190°C and 2.16 kg, wherein the one or more polyolefin copolymers include maleic anhydride-grafted polyolefins and ethylene-vinyl acetate copolymers; and more than 83% by weight of inorganic fillers based on the total weight of the halogen-free flame retardant composition, such inorganic fillers including one or more of talc, CaCO3, magnesium hydroxide, aluminum trihydrate, silicon dioxide, siloxanes, or mica. According to at least one embodiment of this disclosure, a composite panel is provided. Embodiments of the composite panel may include a first metal layer; a second metal layer; a core layer disposed between the first metal layer and the second metal layer; a first connecting layer disposed between the first metal layer and the core layer; and a second connecting layer disposed between the second metal layer and the core layer; wherein the core layer comprises the halogen-free flame retardant composition described herein. According to at least one embodiment of this disclosure, a method for manufacturing a composite panel is provided. Embodiments of this method may include extruding a core layer; applying a first connecting layer and a second connecting layer to opposing surfaces of the core layer; and, after application to the core layer, laminating a first metal layer and a second metal layer onto the first connecting layer and the second connecting layer, respectively, to produce a composite panel; wherein the core layer comprises the halogen-free flame retardant composition described herein. These and other embodiments are described in more detail in the following embodiments.

Implementation Method

Claims

1. A halogen-free flame retardant composition comprising: one or more polyolefin copolymers having a melt flow index of 350 g / 10 min to 1000 g / 10 min as measured at 190°C and 2.16 kg, wherein the one or more polyolefin copolymers are composed of maleic anhydride-grafted polyolefins or maleic anhydride-grafted polyolefins and ethylene-vinyl acetate copolymers; at least 83% by weight of an inorganic filler, wherein the inorganic filler comprises CaCO3; and optionally an internal inorganic lubricant.

2. The halogen-free flame retardant composition of claim 1, wherein the halogen-free flame retardant composition comprises less than 17% by weight of the one or more polyolefin copolymers.

3. The halogen-free flame retardant composition of claim 1, wherein the halogen-free flame retardant composition comprises at least 85% by weight of inorganic filler based on the total weight of the halogen-free flame retardant composition.

4. The halogen-free flame retardant composition of any one of claims 1 to 3, wherein the one or more polyolefin copolymers are composed of maleic anhydride-grafted polyolefins and ethylene-vinyl acetate copolymers.

5. A halogen-free flame retardant composition as claimed in any of items 1 to 3, wherein the fuel load of the composition is less than 3 MJ / kg when measured according to EN ISO 1716.

6. A halogen-free flame retardant composition as claimed in any of items 1 to 3, wherein, when measured according to EN ISO 1182, the furnace temperature rise of the composition is less than or equal to about 50°C, the mass loss of the sample is less than or equal to about 50%, and the continuous burning time of the sample is about 20 seconds.

7. The halogen-free flame retardant composition of claim 1, wherein the inorganic filler comprises one or more inorganic fillers selected from the group consisting of BaSO4, CaSO4, silicates, talc, kaolin, clay, mica, silica, inorganic flame retardants and combinations thereof; and wherein the inorganic flame retardant comprises aluminum trihydrate, alumina, magnesium hydroxide, Huntite, boehmite and its adjuvants.

8. The halogen-free flame retardant composition of any one of claims 1 to 3, wherein, when measured at 177°C, the maleic anhydride-grafted polyolefin is a maleic anhydride-grafted polyolefin elastomer with a Brookfield viscosity greater than 8,000 cP.

9. A composite panel, comprising: A first metal layer; A second metal layer; A core layer disposed between the first metal layer and the second metal layer; a first connecting layer disposed between the first metal layer and the core layer; and a second connecting layer disposed between the second metal layer and the core layer; wherein the core layer comprises a halogen-free flame retardant composition as claimed in any one of claims 1 to 8.

10. The composite panel of claim 9, wherein the first metal layer, the second metal layer, or both comprise aluminum.

11. The composite panel as requested in item 9 or 10, wherein the thickness of the core layer is 1 mm to 5 mm.

12. The composite panel as requested in item 9 or 10, wherein the composite panel is of Euroclass A2 fire rating.

13. A method for manufacturing a composite panel as claimed in any one of claims 9 to 12, the method comprising: The core layer was extruded; The first connecting layer and the second connecting layer are applied to the opposite surfaces of the core layer; After being applied to the core layer, the first metal layer and the second metal layer are laminated onto the first connecting layer and the second connecting layer respectively to produce the composite board.

14. The method of claim 13, wherein the first connecting layer and the second connecting layer are applied via co-extrusion or lamination.

15. A halogen-free flame retardant composition comprising: one or more polyolefin copolymers having a melt flow index of 350 g / 10 min to 1000 g / 10 min as measured at 190°C and 2.16 kg, wherein the one or more polyolefin copolymers comprise maleic anhydride-grafted polyolefins or maleic anhydride-grafted polyolefins and ethylene-vinyl acetate copolymers; and at least 83% by weight of an inorganic filler based on the total weight of the halogen-free flame retardant composition, wherein the inorganic filler comprises CaCO3.

Images