Flame retardant compositions for imparting flame retardancy to a wood fiber- based material selected from plywood, chipboard, HDF, LDF, and MDF building panels or OSB building panels

The invention relates to flame retardant compositions for imparting flame retardancy to a wood fiber-based material selected from plywood, chipboard, HDF, LDF, and MDF building panels or OSB building panels.

Background

The demand for fire safe goods/materials, are constantly increasing. Fire safety regulations for many types of goods have caused many manufacturers to make their goods with flame retardant properties. In efforts to comply with these regulations, many manufacturers apply fire retardant chemical compositions to their goods. Unfortunately, many fire retardant chemical compositions are known to contain ingredients that may be toxic to humans and the environment.

Today, the mostly used fire retardant chemical compositions are harmful. Harmful fire resistant compositions include halogenated compositions, especially bromine flame retardants (BFRs) and chlorinated flame retardants (CFRs) which have been used for over 30 years, but it has recently been found that levels of these substances are probably rapidly building up inside the bodies of humans. Among others, have BFRs been linked to cancer, immune suppression, and neurobehavioral and developmental effects.

In the building industry it is also very important to impart the building materials with flame retardant properties to live up to the standards in this area, especially European standard EN13501 -1 fire test and FTPC part 5 & 6 / IMO A653(16) fire tests. The flame retardant used to impart flame retardant properties should not impart any hazards to the people working with and using the flame retardant building materials or the people living in the buildings after they have been build. In addition, the flame retardant composition should be chemically compatible with all the other used building materials e.g. glue, painting, varnish, lacquer, polish and other surface treatment materials.

There is a need for effective non-halogenated flame retardants that are harmless to humans and the environment, which absorb quickly and easy into absorbent materials such as plywood, chipboard, HDF, LDF, and MDF building panels or OSB building panels.

Summary of the invention

The object of the present invention is to solve the above described problems by developing flame retardant compositions that are harmless to humans and the environment.

In a first aspect the present invention relates to a flame retardant composition for imparting flame retardancy in a wood fiber-based material selected from plywood, chipboard, HDF, LDF, and MDF building panels or OSB building panels, comprising:

Aluminiumhydroxid (AI(OH) ₃ );

Melamine cyanurate;

At least one glue selected from urea-formaldehyde, melamin-urea- formaldehyde or polyurethane or a mixture of one or more thereof;

wherein the ratio of the Aluminiumhydroxid (AI(OH) ₃ ) is at least 5 times higher than the ratio of Melamine cyanurate.

As claimed, the wood fiber-based material can be any of plywood, chipboard, HDF, LDF, and MDF building panels or OSB building panels.

In a second aspect the present invention relates to a method of imparting flame retardancy to a wood fiber-based material, comprising applying a composition according to the first aspect of the invention to the wood fiber-based material during manufacturing of the wood fiber-based material.

In a third aspect the present invention relates to a fire resistant wood fiber-based material comprising the composition according to the first aspect of the present invention. The fire resistant wood fiber-based material can be plywood or chipboard, MDF, LDF or HDF building panels or OSB building panels.

The present invention in a fourth aspect relates to a flame retardant composition for imparting flame retardancy to a surface of a wood fiber-based material selected from plywood, chipboard, HDF, LDF, and MDF building panels or OSB building panels, comprising:

At least one organic acid;

At least one surfactant;

- At least one carbonate compound;

- At least one urea compound;

At least one lye or week base.

The present invention in a fifth aspect relates to a method of imparting flame retardancy to the surface of a wood fiber-based material, comprising applying a composition according to the fourth aspect of the present invention to the surface of the wood fiber-based material. The fire resistant wood fiber-based material can be plywood or chipboard, MDF, LDF or HDF building panels or OSB building panels. The present invention in a sixth aspect relates to a fire resistant wood fiber-based material comprising the composition according to the fourth aspect of the present invention. The fire resistant wood fiber-based material can be plywood or chipboard, MDF, LDF or HDF building panels or OSB building panels. The present invention in a seventh aspect also concerns a method of imparting flame retardancy to a wood fiber-based material, comprising applying a composition according to the first aspect of the invention to the wood fiber-based material during manufacturing of the wood fiber-based material followed by applying a composition according to the fourth aspect of the invention to the surface of the wood fiber-based material. The fire resistant wood fiber-based material can be plywood or chipboard, MDF, LDF or HDF building panels or OSB building panels.

Description of preferred embodiments

In the following description, specific details will be provided to give a thorough understanding of the present invention. As will be evident to one skilled in the art, however, the exemplary embodiments may be practiced without these specific details. The present invention in a first aspect relates to a flame retardant composition for imparting flame retardancy in a wood fiber-based material selected from plywood, chipboard, HDF, LDF, and MDF building panels or OSB building panels, comprising:

Aluminiumhydroxid (AI(OH) ₃ );

Melamine cyanurate;

At least one glue selected from urea-formaldehyde, melamin-urea- formaldehyde or polyurethane or a mixture of one or more thereof;

wherein the ratio of the Aluminiumhydroxid (AI(OH) ₃ ) is at least 5 times higher than the ratio of Melamine cyanurate.

As claimed, the wood fiber-based material can be any of plywood, chipboard, HDF, LDF, and MDF building panels or OSB building panels.

In one embodiment, the invention relates to a flame retardant composition comprising:

Aluminiumhydroxid (AI(OH) ₃ );

Melamine cyanurate;

At least one glue selected from urea-formaldehyde, melamin-urea- formaldehyde or polyurethane or a mixture of one or more thereof;

wherein the ratio of the Aluminiumhydroxid (AI(OH) ₃ ) is at least 5 times higher than the ratio of Melamine cyanurate.

The present composition will penetrate the wood material which means that the application of the composition onto the material can be conducted very efficient and fast as the composition quickly will penetrate the wood material. A big advantage of the present composition according to the first aspect of the invention is that it contains glue which means that it can be applied as glue and behaves as glue. This means that the present flame retardant composition e.g. can be applied to every single layer of ply wood followed by pressing the several layers together afterwards - giving a homogenous flame retardant plywood building material since the composition is even distributed throughout the material. The present flame retardant composition can e.g. also be added to the wood fiber-based material during the manufacturing of the wood fiber-based material e.g. chipboard, MDF building panels, OSB building panels. The composition is mixed together with the fibers making up the wood fiber-based material and the composition is preferably mixed together by mechanical mixing. This will give a homogenous flame retardant building material since the composition is even distributed throughout the material. As mentioned, the ratio of the Aluminiumhydroxid (AI(OH) ₃ ) is at least 5 times higher than the ratio of Melamine cyanurate meaning that the ratio of Aluminiumhydroxid to Melamine cyanurate is at least 5:1 . In one embodiment of the composition according to the first aspect of the invention the ratio of the Aluminiumhydroxid (AI(OH) ₃ ) is at least 6 times higher than the ratio of Melamine cyanurate meaning that the ratio of Aluminiumhydroxid to Melamine cyanurate is at least 6:1 or where the ratio of the Aluminiumhydroxid (AI(OH) ₃ ) is at least 7 times (meaning that the ratio of Aluminiumhydroxid to Melamine cyanurate is at least 7:1 ), or at least 8 times (meaning that the ratio of Aluminiumhydroxid to Melamine cyanurate is at least 8:1 ), or at least 9 times (meaning that the ratio of Aluminiumhydroxid to Melamine cyanurate is at least 9:1 ) or at least 10 times higher than the ratio of Melamine cyanurate (meaning that the ratio of Aluminiumhydroxid to Melamine cyanurate is at least 10:1 ).

In one embodiment of the composition according to the first aspect of the invention the glue will be present in the amount of between 20 to 80 %wt, such as between 40 to 60 %wt or approx. 50 %wt of the total weight of the composition.

In one embodiment of the composition according to the first aspect of the invention the total amount of Aluminiumhydroxid and Melamine cyanurate will be between 10 to 50 %wt, such as between 20 to 40 %wt or approx. 30 %wt of the total weight of the composition.

In one embodiment of the composition according to the first aspect of the invention the glue is melamin-urea-formaldehyde. In one embodiment of the composition according to the first aspect of the invention the glue is urea-formaldehyde. In one embodiment of the composition according to the first aspect of the invention the glue is polyurethane. In one embodiment the composition according to the first aspect of the invention further comprises a thickening agent. The thickening agent is preferably present in the amount of 0.1 to 15 wt%. More preferably, the thickening agent makes up about from 0.5 to 10 wt%, or from 1.0 to 10 wt%, or from 2 to 10 wt% of the composition, and most preferably, it makes up about from 5 to 10 wt% of the composition. The thickening agent can be flour, starch, carboxymethyl cellulose (CMC) or polyvinyl acetates (PVAc). The amount of thickening agent imparts the viscosity of the composition. In one embodiment the composition according to the first aspect of the invention further comprises a hardener. The hardener can be selected from ammonium sulphate, formic acid, oxalic acid, ammonium chloride, sulphoric acid, phosphoric acid, citric acid, ammonium nitrate or aluminium chloride. Preferred hardeners when the glue is melamin-urea-formaldehyde are: ammonium sulphate, formic acid, oxalic acid, ammonium chloride, sulphoric acid, phosphoric acid. Preferred hardeners when the glue is urea-formaldehyde are: oxalic acid, citric acid, ammonium chloride, ammonium nitrate, aluminium chloride. The hardening agent is preferably present in the amount of 0.1 to 10 wt%. More preferably, the hardening agent makes up about from 0.5 to 8 wt%, or from 1.0 to 5 wt%, or from 2 to 3 wt% of the composition.

It is important that the composition has a low viscosity when the composition is applied as a liquid through nozzles onto the wood fiber-based material. When the composition is applied as a liquid through nozzles onto the absorbent material the thickening agent may be left out of the composition. The viscosity is preferably between 500 to 3000 mPas at 20°C when the composition is applied as a liquid through nozzles.

It is on the other hand important that the viscosity is high when the composition is applied as a liquid by use of roller application onto the absorbent material. When the composition is applied as a liquid by use of roller application onto the absorbent material the thickening agent is preferably added to the composition in amount as specified above. The viscosity is preferably between 1000 and up to 10000 mPas at 20°C when the composition is applied as a liquid by use of roller application The viscosity is in one embodiment between 3000 and 7000 mPas at 20°C when the composition is applied to the wood fiber-based material by use of roller application.

In one embodiment the composition according to the first aspect of the invention further comprises an aqueous solvent to adjust the viscosity. The aqueous solvent can be any type of solvent that comprises water. For example, the aqueous solution may be tap water or distilled water. For those embodiments of the glue that include an aqueous solvent, the solvent preferably makes up between about 5% and about 15% of the composition.

In one embodiment the composition of the present invention consist of ingredients that are not harmful to neither living species nor the environment. The composition preferably contains no halogens. It was surprisingly found that by adding aluminiumhydroxid (AI(OH) ₃ ) and melamine cyanurate to the glue; the temperature constancy of the glue was increased. Without the added aluminiumhydroxid (AI(OH) ₃ ) and melamine cyanurate the glue will decompose and in regards of the plywood the layers will unleash from each other and the fire will flare due to the larger surface area. By adding aluminiumhydroxid (AI(OH) ₃ ) and melamine cyanurate to the glue, the power of the glue improved.

The composition according to the first aspect of the present invention can be manufactured in many possible ways. The ingredients can be mixed in any suitable way. In the following one way of mixing the ingredients of the composition is discussed. This is merely for illustrative purposes and a person skilled in the art will realize that many other ways of mixing the components are possible. In one embodiment, the Aluminiumhydroxid (AI(OH) ₃ ) and the Melamine cyanurate are mixed together (powder) followed by mixing with the glue, followed by mixing in the thickening agent and the hardener. If adjustment of the viscosity is needed, the aqueous solvent may be mixed together with the mixture at the end. The composition is now ready to be used. This is only one example as to how the ingredients can be combined, and it will be apparent to one skilled in the art that there exist numerous other mixing methods that can be used. In the following first a general mixing scheme of the ingredients of the composition is shown. A person skilled in the art will realize that many other ways (other amount of the different component) of mixing the components are possible.

In the following one specific formula of mixing the ingredients of the composition is shown. A person skilled in the art will realize that many other ways (other amount of the different component) of mixing the components are possible.

Fire tests:

The fire resistant wood fiber-based materials comprising the composition according to the first aspect of the present invention are tested and classified according to the test known in the industry.

Below are the results.

Type Plywood

Wood species Birch

glue composition (first aspect of the invention) 180 - 200 g/m Classification B-S1 , dO

Standard EN13823:2010

So by using the composition according to the first aspect of the present invention the fire classification is improved and classified as Class B. The present invention in a second aspect concerns a method of imparting flame retardancy to a wood fiber-based material, comprising applying a composition according to the first aspect of the invention to the wood fiber-based material during manufacturing of the wood fiber-based material. In one embodiment of the method according to the second aspect of the present invention, the applied composition is applied to the wood fiber-based material by use of roller application. A variety of different rollers can be used to apply the present composition by use of roller application to be able to control the applied amount of composition. A smooth or grooved roller is preferably used.

In one embodiment of the method according to the second aspect of the present invention the composition is added to the wood fiber-based material during the manufacturing. The wood fiber-based material can be chipboard, MDF, HDF or LDF building panels, OSB building panels. The composition is mixed together with the fibres making up the wood fiber-based material. All the components are mixed, preferably by mechanical mixing by two screw conveyer.

In one embodiment of the method according to the second aspect of the present invention, the composition is applied to every single layer of ply wood followed by pressing the several layers together afterwards - giving a homogenous flame retardant plywood building material since the composition is even distributed throughout the material.

The present invention in a third aspect relates to a fire resistant wood fiber-based material comprising the composition according to the first aspect of the present invention. The fire resistant wood fiber-based material can be plywood or chipboard, MDF, LDF or HDF building panels or OSB building panels. The present invention in a fourth aspect relates to a flame retardant composition for imparting flame retardancy to a surface of a wood fiber-based material selected from plywood, chipboard, HDF, LDF, and MDF building panels or OSB building panels, comprising:

At least one organic acid;

At least one surfactant;

At least one carbonate compound;

- At least one urea compound;

At least one lye or week base.

In one embodiment the present invention (according to the fouth aspect) relates to a flame retardant composition comprising:

At least one organic acid;

- At least one surfactant;

At least one carbonate compound;

- At least one urea compound;

At least one lye or week base. In one embodiment according to the fourth aspect of the present invention, the organic acid can be selected from citric acid or acetic acid. In some embodiments, the acid is a carboxylate. Preferably, a carboxylate is used that provides a source of citrate ion. Citric acid may be an especially suitable material, as it is a relatively gentle acid. The amount of acid will depend on the type of the acid used and can vary throughout a wide range. In one embodiment citric acid is present in the amount from 7 to 27 %wt of the composition or from 20 to 25 %wt of the composition.

The composition according to the fourth aspect of the present invention comprises at least one surfactant, preferably in the range from 0.01 to 1 wt%. The presence of this surfactant is important to reduce the surface tension of the liquid composition when applied to a material. It allows the composition to penetrate solid and therefore works as a wetting agent. This is especially important in the present invention as the composition is meant for imparting flame retardancy onto the surface of a wood fiber-based material and therefore has to penetrate easy into the material. Preferably, the surfactant makes up about 0.05 to 1 wt% of the composition or about 0.05 to 0.5 wt% of the composition. More preferably, the surfactant makes up about 0.1wt% of the composition. In one embodiment the surfactant is sodium dihexyl sulfosuccinate. In one embodiment the surfactant is an alcohol such as ethoxylated alcohol. In one embodiment the surfactant is a glycol such as ethylene or propylene. In one embodiment the surfactant is a mixture of the above listed alcohols and/or glycols. The amount of added surfactant is very small compared to the rest of the composition.

In one embodiment according to the fourth aspect of the present invention, the carbonate compound can be selected from carbonates having a metal ion M+, M2+ or M3+.ln one embodiment the carbonate compound can be selected from Na ₂ C0 _3, NaHC0 ₃ , Na ₃ H(C0 ₃ ) ₂ , K ₂ C0 ₃ , KHC0 ₃ , MgC03, Mg(HC0 ₃ ) ₂ , CaC0 ₃ or Ca(HC0 ₃ ) ₂ . In one embodiment the carbonate compound is natrium hydrogencarbonate. The carbonate is a filler and the acid in the composition will react with the carbonate to form C0 ₂ . In one embodiment the carbonate compound is present in the amount from 5 to 20 %wt of the composition such as from 10 to 18 %wt of the composition. In one embodiment according to the fourth aspect of the present invention, the urea compound can be urea. In one embodiment the urea compound is present in the amount from 4 to 20 %wt of the composition, or in the amount from 10 to 15 %wt of the composition. In one embodiment according to the fourth aspect of the present invention, the lye can be selected from soda lye (sodium hydroxide) or potassium hydroxide. In one embodiment according to the fourth aspect of the present invention the week base can be selected from ammonia and ethylamine. In one embodiment the lye or week base is present in the amount from 3 to 15 % wt of the composition, or in the amount from 5 to 10 % wt of the composition.

In one embodiment according to the fourth aspect of the present invention, the composition further comprises an aqueous solvent. The aqueous solvent can be any type of solvent that comprises water. For example, the aqueous solution may be tap water or distilled water. For those embodiments of the composition that include an aqueous solvent, the solvent preferably makes up between 30 % wt and 80% wt of the composition such as between 35 % wt and 50% wt of the composition. In one embodiment the composition of the present invention consist of ingredients that are not harmful to neither living species nor the environment. The composition preferably contains no halogens.

The composition according to the fourth aspect of the present invention will penetrate the absorbent material which means that the application of the composition onto the material can be conducted very efficient and fast as the composition quickly will penetrate the surface of the wood fiber-based material.

The organic acid is together with the lye included/added to regulate the pH level of the composition such that the fire retardant properties of the composition are enhanced. Although the pH can vary throughout a wide range, the pH of the composition is preferably below pH 7. In one embodiment the pH is in the range of about 4 to 6, more preferably about 5. The acid can be of any suitable type mentioned above.

In one embodiment the composition according to the fourth aspect of the present invention further comprise a defoamer. The defoamer is preferably present in the amount of from 0.05 to 1 .0 wt%. More preferably, the defoamer makes up about from 0.05 to 0.5 wt% or from 0.05 to 0.3 wt% of the composition, and most preferably, it makes up about 0.1 to 0.3 wt% of the composition. In one embodiment the defoamer is an emulsified petroleum. The defoamer reduces the amount of foam created by the presence of C0 ₂ , especially during the mixing phase when the aqueous solvent is mixed with the composition. In one embodiment the composition according to the fourth aspect of the present invention further comprises a thickening agent.

It is important that the composition according to the fourth aspect of the present invention has a low viscosity when the composition is applied as a liquid through nozzles onto the absorbent material. When the composition is applied as a liquid through nozzles onto the surface of the wood fiber-based material the thickening agent may be left out of the composition. The viscosity is preferably between 1 to 100 mPas at 20°C when the composition is applied as a liquid through nozzles. The viscosity is in one embodiment around 1 mPas at 20°C when the composition is applied as a liquid through nozzles.

It is on the other hand important that the viscosity is high when the composition according to the fourth aspect of the present invention is applied as a liquid by use of roller application onto the surface of the wood fiber-based material. The viscosity is preferably between 10 and up to 5000 mPas at 20°C when the composition is applied as a liquid by use of roller application. The viscosity is in one embodiment between 100 and 150 mPas at 20°C when the composition is applied as a liquid by use of roller application.

In one embodiment the composition according to the fourth aspect of the invention further comprises a preservative. The preservative is preferably present in the amount of 0.02 to 5 wt%. More preferably, the preservative makes up about 0.02 to 1.5 wt% of the composition, and most preferably, it makes up about 0.1 to 1 .0 wt% of the composition. The preservative is added to prevent growth of bacteria or mold during transport and/or storage of the composition. Any suitable preservative can be used to serve this purpose. In one embodiment the preservative is a benzoate ion e.g. a benzoic acid. In one embodiment the preservative is sodiumbenzoate. In one embodiment the preservative is a food approved preservative.

The composition according to the fourth aspect of the present invention can be manufactured in many possible ways. The ingredients can be mixed in any suitable way. In the following one way of mixing the ingredients of the composition is discussed. This is merely for illustrative purposes and a person skilled in the art will realize that many other ways of mixing the components are possible. The aqueous solvent and the urea compound are mixed until the ingredients are thoroughly mixed together. The at least one acid and carbonate are added alternating and mixed until all of the ingredients are thoroughly mixed together. The lye is added afterwards when the mixture has reach a temperature around 5 degrees. If the composition comprises additional ingredients they can be added as well to the mixture and thoroughly mixed together with the main ingredients. The composition is now ready to be used. This is only one example as to how the ingredients can be combined, and it will be apparent to one skilled in the art that there exist numerous other mixing methods that can be used.

In the following first a general mixing scheme of the ingredients of the composition is shown. A person skilled in the art will realize that many other ways (other amount of the different component) of mixing the components are possible.

In the following one specific formula of mixing the ingredients of the composition is shown. A person skilled in the art will realize that many other ways (other amount of the different component) of mixing the components are possible.

Fire tests:

The fire resistant wood fiber-based materials comprising the composition according to the fourth aspect of the present invention are tested and classified according to the test known in the industry.

Below are the results. Type Plywood Solid wood Plywood

Wood species Spruce Douglas Spruce glue mixture (standard phenol Melamine urea adhesive applied formaldehyde by the plywood

producer)

Surface composition (fourth 170 g/m ² 160 g/m ² 150 g/m ² aspect of the invention)

Classification B-S1 , dO B-S1 , dO B-S1 , dO

Standard EN 13823:2010 EN 13823:2010 EN 13823:2010

So by using the composition according to the fourth aspect of the present invention the fire classification is improved from Class D to Class B. The present invention in a fifth aspect relates to a method of imparting flame retardancy to the surface of a wood fiber-based material, comprising applying a composition according to the fourth aspect of the present invention to the surface of the wood fiber-based material. The fire resistant wood fiber-based material can be plywood or chipboard, MDF, LDF or HDF building panels or OSB building panels.

In one embodiment according to the fifth aspect of the present invention, the composition is applied to the surface of the wood fiber-based material by use of roller application. A variety of different rollers can be used to apply the present composition by use of roller application to be able to control the applied amount of composition. A smooth or grooved roller is preferably used.

In one embodiment according to the fifth aspect of the present invention, the composition is sprayed onto the surface of the wood fiber-based material. The present invention in a sixth aspect relates to a fire resistant wood fiber-based material comprising the composition according to the fourth aspect of the present invention. The fire resistant wood fiber-based material can be plywood or chipboard, MDF, LDF or HDF building panels or OSB building panels. The present invention in a seventh aspect also concerns a method of imparting flame retardancy to a wood fiber-based material, comprising applying a composition according to the first aspect of the invention to the wood fiber-based material during manufacturing of the wood fiber-based material followed by applying a composition according to the fourth aspect of the invention to the surface of the wood fiber-based material. The fire resistant wood fiber-based material can be plywood or chipboard, MDF, LDF or HDF building panels or OSB building panels.

In one embodiment of the method according to the seventh aspect of the present invention the composition according to the first aspect of the present invention is added to the wood fiber-based material during the manufacturing. The wood fiber- based material can be chipboard, MDF, HDF or LDF building panels, OSB building panels. The composition according to the first aspect of the present invention is mixed together with the fibres making up the wood fiber-based material. All the components are mixed, preferably by mechanical mixing by two screw conveyer. The wood fiber-based material can in one embodiment be pressed together after this step before applying the composition according to the fourth aspect of the present invention to the surface of the wood fiber-based material. In another embodiment (which is the case for at least the OSB building panels), the composition according to the fourth aspect of the present invention is applied before the pressing step is conducted.

The step of applying a composition according to the fourth aspect of the present invention to the surface of the wood fiber-based material material can be done by use of roller application or spraying the composition onto the surface of the wood fiber-based material. A variety of different rollers can be used to apply the present composition by use of roller application to be able to control the applied amount of composition. A smooth or grooved roller is preferably used. In one embodiment of the method according to the seventh aspect of the present invention the composition according to the first aspect of the present invention is applied to every single layer of ply wood followed by pressing the several layers together afterwards - giving a homogenous flame retardant plywood building material since the composition is even distributed throughout the material. This is followed by applying a composition according to the fourth aspect of the present invention to the surface of the wood fiber-based material material. This can be done by use of roller application or spraying the composition onto the surface of the wood fiber-based material. A variety of different rollers can be used to apply the present composition by use of roller application to be able to control the applied amount of composition. A smooth or grooved roller is preferably used.

Fire tests:

The finished fire resistant wood fiber-based materials comprising the composition according to the first aspect and the fourth aspect of the present invention are tested and classified according to the test known in the industry.

Below are the results.

Type Plywood

Wood species Birch

glue composition (first aspect of the invention) 240 g/m ²

Surface composition (fourth aspect of the invention) 180 g/m ²

Classification B-S1 , dO

Standard EN13501 +A1 :2009

Type Plywood

Wood species Birch

glue composition (first aspect of the invention) 240 g/m

Surface composition (fourth aspect of the invention) 150 g/m ²

Classification B-S1 , dO

Standard EN13823:2010

Type Oak Veneer

Wood species Fire retarded MDF glue composition (first aspect of the invention) 180 - 200 g/m ²

Surface composition (fourth aspect of the invention) 125 g/m ²

Classification B-S1 , dO Standard EN13823:2010

So by using the composition according to the first aspect of the present invention and the fourth aspect of the present invention the fire classification is improved and classified as Class B.