Furan resin composition

Abstract

The invention relates to a resin composition for producing a precursor material for forming a fibre-resin composite for use in the interior of aircraft, the resin composition comprising furan resin and functional additives. The composition further comprises a synergistic combination of a curing agent, a fire protection additive, and an additional toughness modifier, wherein the fire protection additive is a phosphate-containing additive and the toughness modifier is fumed silica and / or a polyvinyl acetal or copolymers thereof, which mix with the composition without macroscopic phase separation.

Description

[0001] FURAN RESIN COMPOSITION

[0002] The invention relates to a resin composition for producing a precursor material for forming a fiber-resin composite for use in the interior of aircraft, wherein the resin composition comprises furan resin and functional additives.

[0003] In addition, the invention relates to a pre-material (prepreg) for forming a fiber-resin composite for use in the interior of aircraft and a fiber-resin composite for use in the interior of aircraft.

[0004] It is known that components made of fiber-resin composites are used in aircraft interiors. These components must exhibit certain properties that are very specific to aircraft interiors and cannot be compared with other applications, such as automotive interiors. Mechanical properties and fire protection properties are particularly important. Regarding fire protection properties, there are specific tests for suitability in aircraft interiors:

[0005] - How long does it take for the composite to ignite in the event of a fire?

[0006] - How much smoke is produced?

[0007] - How toxic is the smoke?

[0008] - How much heat is released during a fire?

[0009] The heat release rate is particularly relevant in aircraft applications. Regarding the heat release rate, different requirements are placed on components made of fiber-resin composites in aircraft applications than, for example, in automobiles. Typical requirement profiles arise, for example, from Airbus material specifications for the transportation sector, which set the necessary mechanical performance and the fire protection performance to be met in very strict terms.

[0010] It is known to produce fiber-resin composites for use in the interior of aircraft from phenolic resins, which are one of the few thermoset classes that have sufficient flame-retardant properties.

[0011] Phenolic resins are manufactured from petrochemical raw materials and have the additional disadvantage of containing carcinogenic components that pose significant health risks to the manufacturer of the raw material and the composite. Another disadvantage is that phenolic resins do not, or only with difficulty, meet manufacturing standards regarding environmental compatibility.

[0012] To overcome these disadvantages, it is known to produce fiber-resin composites for use in aircraft interiors based on a composition of furan resins and additives. Furan resins can be produced from renewable raw materials and inherently exhibit certain flame-retardant properties.

[0013] The possibility of producing furan resins based on renewable raw materials makes them particularly interesting in terms of increased sustainability.

[0014] If furan resins are used without modifications, some disadvantages arise:

[0015] - Poor prepreg quality, particularly excessive stiffness due to excessive drying or excessively viscous consistency. - Inadequate mechanical performance, below the expected values ​​of typical reactive resin systems for the application.

[0016] - Long pressing times, which make the material unsuitable for component production in fast processing processes.

[0017] - Insufficient fire protection performance for components used in the interior of aircraft because the heat release is too high.

[0018] Furan resin compositions are known from which products with fundamental suitability for the widest possible range of applications can be manufactured.

[0019] Common furan resins often have the disadvantage of containing significant amounts of residual monomers (such as furfuryl alcohol), which have potentially carcinogenic and / or toxic properties. This poses a significant health risk for prepreg and component manufacturers.

[0020] However, a specific adaptation for use in aircraft interiors to process a furan resin into a prepreg with properties comparable to the advantageous properties of phenolic resins in terms of fire protection properties is not known.

[0021] As already described, resin compositions made from furan resin without modifiers / additives are unsuitable. Therefore, additional substances must be added. To improve fire-protection properties, it is known to use fire-protection additives. To increase toughness, it is known to use toughness modifiers.

[0022] However, during the development of the resin composition, it became apparent that fire-protection additives can have a negative impact on toughness, and that toughness modifiers can sometimes have a significant negative impact on fire-protection properties. A simple combination of these substances therefore does not generally lead to a suitable composition with a stable balance of the required properties.

[0023] The invention is based on the object of providing a phenol resin-free resin composition based purely on furan resins, with which products can be manufactured that specifically meet the application profile of properties for use in the interior of aircraft.

[0024] In particular, it is an object of the invention to improve the processability of the resin composition and the mechanical properties (especially the impact and fracture toughness) as well as the fire protection properties (especially the heat release rate) of the products manufactured therefrom (prepreg and composite).

[0025] This object is achieved according to the invention by a resin composition having the features of claim 1.

[0026] In addition, this object is achieved by a precursor material having the features of claim 10 and by a fiber-resin composite having the features of claim 13.

[0027] Preferred embodiments of the invention are the subject of the dependent claims.

[0028] During the development of the resin composition, it has surprisingly been shown that the interaction of specific substances produces a synergistic effect. In particular, the interaction of a curing agent in combination with certain fire-protection additives and toughness modifiers results in a surprisingly good balance of impact and fracture toughness and fire-protection properties.

[0029] In particular, it has been shown that certain toughness modifiers not only improve the processability of the resin composition and the mechanical properties of the products made from it, but that these substances, in combination with a curing agent, have no or a relatively low negative impact on the fire protection properties. Furthermore, it has been shown that certain fire protection additives not only improve the fire protection properties, but in combination with a curing agent, have no or a relatively low negative impact on toughness.

[0030] This synergistic effect of certain materials to achieve a stable balance between mechanical properties and fire properties was not known.

[0031] According to the invention, a synergistic combination of a curing agent, a fire protection additive which, in interaction with the other substances, does not adversely affect the toughness of the resin composition, and an additional toughness modifier which, in interaction with the other substances, does not adversely affect the fire protection properties of the resin composition, is therefore provided.

[0032] This synergistic effect is achieved according to the invention when the fire protection additive is a phosphate-containing additive and the toughness modifier is fumed silica and / or a polyvinyl acetal or its copolymers, which mix with the composition without macroscopic phase separation. Within the scope of the invention, the resin composition is preferably free of phenolic resins or other reactive resin systems, such as, for example, epoxy resins or polyurethane. Within the scope of the invention, the resin composition is particularly preferably a pure furan resin composition, i.e. the resin is exclusively furan resin and not a mixture of furan resin and another resin.

[0033] In a particularly preferred embodiment of the invention, the furan resin is a prepolymer based on furfuryl alcohol. This prepolymer is used with the lowest possible proportion (<1%) of residual monomer.

[0034] A particularly stable balance of desired properties can be achieved if the fire protection additive is ammonium polyphosphate (APP) and the polyvinyl acetal is polyvinyl butyral (PVB) or its copolymers, which mix with the composition without macroscopic phase separation.

[0035] In a particularly preferred embodiment of the invention, the curing agent is a Lewis acid or a Brønsted acid.

[0036] In a preferred embodiment of the invention, functional additives are provided, in particular dispersants and / or surface additives and / or anti-sedimentation additives.

[0037] In order to comply with environmental requirements, it is preferably provided within the scope of the invention that the furan resin and / or the additives are produced on the basis of renewable and / or recycled raw materials.

[0038] The resin composition according to the invention can be applied to fibers, whereby—as is known per se—a prepreg can be produced under the influence of heat. The prepreg (precursor material) can be further processed into fiber composite panels, which can be used specifically in aircraft interiors.

[0039] Within the scope of the invention, the fibers may be glass fibers and / or carbon fibers and / or aramid fibers and / or natural fibers and / or basalt fibers.

[0040] After evaporation of the solvent contained in the original resin composition, the solvent-free resin composition in the prepreg (precursor material) can consist of at least 50 wt.% of renewable and / or recycled raw materials, ideally more than 75 wt.%.

Claims

Claims:

1. A resin composition for producing a precursor material for forming a fiber-resin composite for use in the interior of aircraft, the resin composition comprising furan resin and functional additives, characterized in that it comprises a combination of a curing agent, a fire protection additive, and an additional toughness modifier, the fire protection additive being a phosphate-containing additive and the toughness modifier being fumed silica and / or a polyvinyl acetal or copolymers thereof which mix with the composition without macroscopic phase separation.

2. Resin composition according to claim 1, characterized in that it is free from phenolic resins or other reactive resin systems, such as epoxy resins or polyurethane.

3. Resin composition according to claim 1 or 2, characterized in that the furan resin is a prepolymer based on furfuryl alcohol.

4. Resin composition according to one of claims 1 to 3, characterized in that the furan resin has a low residual monomer content of <1%.

5. Resin composition according to one of claims 1 to 4, characterized in that the fire protection additive is ammonium polyphosphate.

6. Resin composition according to one of claims 1 to 5, characterized in that the polyvinyl acetal is polyvinyl butyral (PVB) or its copolymers which can be obtained without macroscopic phase separation with the composition mix is.

7. Resin composition according to one of claims 1 to 6, characterized in that the curing agent is a Lewis acid or a Bronsted acid.

8. Resin composition according to one of claims 1 to 7, characterized in that further functional additives are provided, in particular solvents, dispersants and / or surface additives and / or anti-sedimentation additives.

9. Resin composition according to one of claims 1 to 8, characterized in that the furan resin and / or the additives is / are produced on the basis of renewable and / or recycled raw materials.

10. A precursor material for forming a fiber-resin composite for use in the interior of aircraft, characterized in that it comprises fibers and a resin composition according to one of claims 1 to 9.

11. Precursor material according to claim 10, characterized in that the fibers are glass fibers and / or carbon fibers and / or aramid fibers and / or natural fibers and / or basalt fibers.

12. Starting material according to claim 10 or 11, characterized in that the solvent-free resin composition consists of at least 50 wt.% of renewable and / or recycled raw materials, ideally more than 75 wt.%.

13. Fiber-resin composite for use in the interior of aircraft, characterized in that it is made from a raw material according to claims 10 to 12.