EP-3645620-B1 - FIRE-RETARDANT COMPOSITION AND COATING

Inventors

• PERE, JAAKKO
• KUNNARI, VESA

Dates

Publication Date

20260513

Application Date

20180626

Claims (11)

1. A bio-based non-toxic fire-retardant composition, characterized in consisting of a mixture of: - a) fibrillated cellulose nanofibers (CNF) at consistency of 8 to 60%, and - b) at least one type of mineral component, wherein the mineral component is a plate-like or a sheet-like structure selected from mica, montmorillonite, smectite, kaolin or silicate, in a form of wet slurry or paste at weight ratio between 10 to 90% (CNF / mineral component).
2. The fire-retardant composition according to claim 1, characterized in that the weight ratio of the fibrillated cellulose nanofibers and the mineral component is between 25 to 75% (CNF / mineral component).
3. The fire-retardant composition according to claim 1 or 2, characterized in being applicable directly onto a target surface on-site by spraying, painting or rolling.
4. A fire-protective coating having a layered structure, characterized in comprising the fire-retardant composition according to any of claims 1 to 3 as a protective layer on a target surface, in which fibrillated CNF forms a continuous matrix around oriented plate-like mineral components.
5. The fire-protective coating according to claim 4, characterized in having a layered structure of 2 to 20 layers, which total thickness is 100 to 300 µm.
6. The fire-protective coating according to claim 4 or 5, characterized in that the dry weight per square meter of the protective layer is between 40 and 85 g/m 2 .
7. The fire-protective coating according any of claims 4 to 6, characterized in that the coating is certified by EN ISO 11925-2:2010 standard.
8. A method for producing a fire-retardant composition according to any of claims 1 to 3, characterized in - separately disintegrating fibrillated cellulose nanofibers (CNF) to form a homogenous slurry of CNF at consistency of 8 to 60%, and a uniform mineral component solution, - adding the mineral component solution to the CNF slurry under high shear mixing for at least 30 minutes to obtain a uniform slurry at weight ratio between 10 to 90% (CNF / mineral component).
9. The method according to claim 8, characterized in that the weight ratio of the fibrillated cellulose nanofibers and the mineral component is between 25 to 75% (CNF / mineral component).
10. Use of the fire-retardant composition according to any of claims 1 to 3 and/or the fire-protective coating according to any of claims 4 to 7 on plastic, paper, carton, cellulose, wood and metal surfaces for fire protection.
11. Use of the fire-retardant composition according to any of claims 1 to 3 and/or the fire-protective coating according to any of claims 4 to 7 on surfaces comprising cellulose or other natural fibrous material, forming chemical bonds together with the fire-retardant composition and/or fire-protective coating.

Description

FIELD The present invention relates to fire protective compositions and structures comprising high consistency nanofibrillated cellulose together with mineral components, which provide easy direct applicability onto a target surface. BACKGROUND Flame retardants are a diverse group of chemicals, which are added to manufactured materials as finishes or coatings. Flame retardants inhibit spread of fire by suppressing the chemical reactions in the flame or by the formation of a protective layer on the surface of the material. Current opinion on environmental and health issues is a controversial point, but there are reports on unreliability, environmental harmfulness and health hazards of these compounds. Fire protection of combustible structures is typically managed by fire retardant chemicals. Efficiency of these chemicals is sometimes questioned and they may also pose toxic hazards, for example halogenated compounds are recalcitrant in nature and can be enriched in food chains. For these reasons nontoxic, bio-based fire retardants are of industrial interest. Novel bio-based fire retardants derived from natural resources would provide safer and sustainable chemical burden reducing solutions into ecosystems. Carosio et al. (2015) and Liu et al. (2011) describe and characterize cellulose nanofiber (CNF)/clay nanocomposites, which are prepared by simple filtration. These nanocomposites are reported to have superior fire protection properties. The authors have identified the physical and chemical mechanisms behind the composites and concluded that the properties relate to the unique nanostructure and its low thermal conductivity, as well as high gas barrier properties and material interactions for char formation. In these prior art methods, the protective layers are obtained from very dilute suspensions (1-2%) by filtration. Thus, the methods are slow to carry out and require large amounts of water to be removed and/or evaporated. FI 126698 B describes a method for producing fibrillated cellulose material in an improved and energy efficient way. The method combines fibrillation of high consistency cellulose-based starting material by a specific enzyme mix and non-grinding mechanical mixing. The method provides a fibrillated cellulose material for various uses, and a suitable starting point for the present invention. SUMMARY OF THE INVENTION The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims. According to a first aspect of the present invention, there is provided a bio-based fire-retardant composition in which high consistency nanofibrillated cellulose preferably together with a mineral component(s) self-assembly as a fire protective layer, which is easily applicable to target surfaces. According to a second aspect of the present invention, there is provided a fire-protective coating having a layered structure and comprising the fire-retardant composition. According to a third aspect of the present invention, there is provided a use of the fire-retardant composition on various natural surfaces. These and other aspects, together with the advantages thereof over known solutions are achieved by the present invention, as hereinafter described and claimed. The fire-retardant composition of the present invention is mainly characterized by what is stated in the characterizing part of claim 1. The fire-protective coating of the present invention is mainly characterized by what is stated in the characterizing part of claim 4. The use of the fire-retardant composition of the present invention is mainly characterized by what is stated in claims 10 and 11. Considerable advantages are obtained by means of the invention. For example, totally bio-based and chemical composition of this invention is sustainable, environmentally safe and does not induce health hazards. The fire-protective layer can be applied directly on to surface on-site. In addition to direct application, fast drying on to the surfaces provides advantage over low consistency nanocellulose related solutions. Next, the present technology will be described more closely with reference to certain embodiments. EMBODIMENTS The present technology provides bio-based fire-retardant compositions in which high consistency nanofibrillated cellulose preferably together with a mineral component(s) self-assembly as a fire protective layer, which are easily applicable to target surfaces. FIGURE 1 is a SEM image showing high consistency CMF / Kaolin mixture in 50/50 weight ratio. Hexagon-shaped kaolin pigment can be identified within the cross-section image.FIGURE 2 is a SEM image showing layered protective structure adhered on wood surface.FIGURE 3 is a photo describing the outlook of washed and dewatered high consistency CNF showing a paste-like, non-gel nature, which is further easily dispersed for the desired solids content by high shear mixer.FIGURES 4 and 5 are SEM images showing high consistency