Flame Retardant, Method for Its Manufacture and Article Comprising Such Flame Retardant

Abstract

Method for the preparation of a flame retardant, comprising iron and chlorine in the chemical compositions of its components, comprising at least: —providing an iron containing chemical substance —providing a chlorine containing chemical substance, and bringing said iron containing chemical substance and said chlorine containing chemical substance in contact with each other, to thereby form an at least partially volatile ferric chloride acting as a flame poison. The flame retardant thus formed is also contemplated as well as articles to which the flame retardant is applied.

Claims

1-18. (canceled)

19. A method for the preparation of a flame retardant having iron and chlorine in the chemical compositions of its components, comprising the following steps: (a) providing an iron containing chemical substance, (b) providing a chlorine containing chemical substance, and (c) mixing said iron containing chemical substance and said chlorine containing chemical substance, thereby obtaining a mixture that is reactable to form an at least partially volatile ferric chloride upon subsequent heating.

20. The method according to claim 19, wherein char is formed in addition to ferric chloride upon heating of the prepared flame retardant to at least 150° C.

21. The method according to claim 19, wherein the mixture is homogenous with average domain size of less than 500 nm.

22. The method according to claim 21, wherein the average domain size is less than 20 nm.

23. The method according to claim 19, wherein the iron containing chemical substance is selected from the group consisting of ferric hydroxide, ferric carboxylate, ferric salts of substituted carboxylates, ferric complexes of substituted carboxylates, ferric hydroxide carboxylate, ferric phosphate ester, ferric citrate, ferric gluconate, ferric silicate, ferric complexes with ligands comprising nitrogen and ferric substances comprising at least one covalent bond of the type Fe—O—Si, Fe—O—Al, Fe—O—Ti, Fe—O—C or Fe—O—P.

24. The method according to claim 19, wherein the mixture comprises carbon and hydrogen within the chemical composition of one or both of the iron containing chemical substance and the chlorine containing chemical substance, and wherein the atomic ratio of C:H in the mixture is greater than 0.50.

25. The method according to claim 24, wherein the atomic ratio of C:H in the mixture is greater than 1.0.

26. The method according to claim 19, wherein the chlorine containing chemical substance is a chlorinated sugar or a chlorinated waste product or an intermediate from sugar or sweetener production.

27. The method according to claim 19, wherein the chlorine containing chemical substance is a substance comprising nitrogen in its chemical composition, which is at least partially a hydrochloride or quaternary salt with a molar ratio of chloride to nitrogen with a range of 1:1000 to 1:1.

28. The method according to claim 27, wherein the substance comprising nitrogen in its chemical composition is selected from the group consisting of amines, amine oxides, amidines, guanidines, imines and aromatic heterocycles.

29. The method according to claim 19, wherein the chlorine containing substance comprises a covalent C—Cl bond with a dissociation energy that is lower than the dissociation energy of the covalent C—Cl bond in chloromethane and the type of carbon in the C—Cl bond is selected from the group of benzyl carbon, tertiary carbon, and allyl carbon.

30. The method according to claim 29, wherein the chlorine containing chemical substance is a polymer, oligomer or monomer.

31. The method according to claim 19, further comprising a step of mixing of the flame retardant with hydrophobic matter selected from a group comprising binders, thermoplastics, thermosets, waxes, oils, fats and solvents.

32. The method according to claim 19, wherein flame retardant is applied to substances or materials in order to obtain a content of at least 0.01 wt-% Fe and at least 0.01 wt-% Cl based on total weight of a flame retarded material.

33. The method according to claim 19, wherein the iron containing chemical substance and the chlorine containing chemical substance are identical.

34. The method according to claim 19, wherein all starting materials in the preparation of the flame retardant are selected from a group of food contact materials according to the amended Regulation (EU) No 10/2011.

35. A flame retardant or component in flame retardant mixtures prepared by the following steps: (a) providing an iron containing chemical substance, (b) providing a chlorine containing chemical substance, and (c) mixing said iron containing chemical substance and said chlorine containing chemical substance, thereby obtaining a mixture that is reactable to form an at least partially volatile ferric chloride upon subsequent heating.

36. The flame retardant or component according to claim 35, wherein said flame retardant or component in flame retardant mixtures has the form of an aqueous or water dilutable solution or dispersion.

37. The flame retardant or component claim 35, wherein said flame retardant or component is present on a surface selected among a group consisting of paper surface, cardboard surface, wooden surface or within wooden plates, boards, laminates, and particle boards.

38. An article or product comprising at least one of binders, thermoplastics, thermosets, waxes, oils, fats, solvents, wooden plates, boards, laminates, and particle boards, comprising at least one flame retardant from claim 35.

Description

EXAMPLE 1

Iron(III) dihydroxide benzoate

[0040] 1 mole (162 g) of Iron(III) chloride [7705-08-0] was dissolved in 500 g of water under stirring (150-200 min.sup.−1). 3 moles (120 g) of sodium hydroxide [1310-73-2] were dissolved in 500 g of water and added to the solution of Iron(III) chloride under stirring within 5-10 minutes. A brownish cloudy dispersion was formed. A solution of 1 mole (144 g) of sodium benzoate [532-32-1] in 500 g of hot water (70-80° C.) was prepared and added to the brownish cloudy dispersion within 5 minutes under stirring. The mixture was allowed to cool down and kept at about 20° C. for 20 hours. A brown precipitation was formed under a clear and colourless water phase. The precipitation with the average composition Iron(III) dihydroxide benzoate was filtrated and a pasty product was obtained. Loss on dry at 120° C./30 min (LOD@120° C./30 min) was 78 wt-%. No further washing and/or drying was applied. The pasty Iron(III) dihydroxide benzoate (920 g) was mixed with 920 g of ethanol in order to obtain a pourable Iron(III) dihydroxide benzoate with LOD@120° C./30 min 89 wt-%. Iron content (calculated from LOD): 2.9 wt-%. The product comprises a Fe—O—C bond.

EXAMPLE 2

Iron(III) tris(2-ethylhexanoate)

[0041] 1 mole (162 g) of Iron(III) chloride [7705-08-0] was dissolved in 500 g of water under stirring (150-200 min.sup.−1). 3 moles (120 g) of Sodium hydroxide [1310-73-2] were dissolved in 500 g of water and added to the solution of Iron(III) chloride under stirring within 5-10 minutes. A brownish cloudy dispersion was formed. 3 moles (533 g) of neat 2-ethylhexanoic acid [149-57-5] were added under vigorous stirring (400-500 min.sup.−1) within 20 minutes. Stirring was stopped and a phase separation of dark red Iron(III) 2-ethylhexanoate on top of a clear water phase was formed. The oily Iron(III) 2-ethylhexanoate was separated (533 g) and used without further washing and/or drying. Iron content (calculated from chemical composition): 10.1 wt-%. The product comprises a Fe—O—C bond.

EXAMPLE 3

Iron(III) tris(di-2-ethylhexylphosphate)

[0042] 0.2 mole (32 g) of Iron(III) chloride [7705-08-0] was dissolved in 100 g of water under stirring (150-200 min.sup.−1). 0.6 moles (120 g) of sodium hydroxide [1310-73-2] were dissolved in 100 g of water and added to the solution of Iron(III) chloride under stirring within 5-10 minutes. A brownish cloudy dispersion was formed, to which 0.6 mole (227 g) of neat Di-2-ethylhexylphosphoric acid were added under vigorous stirring (400-500 min.sup.−1) within 20 minutes. A viscous to pasty, greyish mass separates from the water phase. The product was isolated and dried on filter paper for 2 hours at 20° C., which yields 248 g of a greyish, viscous pasty product. Loss on dry at 120° C./30 min (LOD@120° C./30 min) was 10 wt-%. The Iron(III) tris(di-2-ethylhexylphosphate) was mixed with 250 g of ethanol under heating to 60-70° C. in order to obtain a pourable dispersion with LOD@120° C./30 min of 48 wt-%. Iron content (calculated from LOD): 2.2 wt-%. The product comprises a Fe—O—P bond.

EXAMPLE 4

Iron(III) trihydroxide

[0043] 0.5 mole (81 g) of Iron(III) chloride [7705-08-0] was dissolved in 250 g of water under stirring (150-200 min.sup.−1). 2 moles (80 g) of sodium hydroxide [1310-73-2] were dissolved in 250 g of water and added to the solution of Iron(III) chloride under stirring within 5-10 minutes. A brownish cloudy dispersion was formed, which was poured into 500 g of water. The Iron(III) hydroxide product settles within 20 hours under a yellowish water phase. The precipitated product was separated and dried on filter paper for 2 hours at 20° C., which yields 234 g of a brown, pasty product. Loss on dry at 120° C./30 min (LOD@120° C./30 min) was 82 wt-%. The pasty Iron(III) trihydroxide was mixed with 120 g of ethanol in order to obtain a pourable Iron(III) trihydroxide with LOD@120° C./30 min of 88 wt-%. Iron content (calculated from LOD): 6.2 wt-%.

EXAMPLE 5

Sucralose (1,6-Dichloro-1,6-dideoxy-β-D-fructofuranosyl-4-chloro-4-deoxy-α-D-galactopyranosid)

[0044] 0.05 moles (20 g) of sucralose (1,6-Dichloro-1,6-dideoxy-β-D-fructofuranosyl-4-chloro-4-deoxy-α-D-galactopyranosid, [56038-13-2] were dissolved in 10 g of water and 30 g ethanol under warming in order to obtain a 33 wt-% solution. Chlorine content (calculated): 8.9 wt-%

EXAMPLE 6

[0045] 0.4 mole (38 g) guanidine hydrochloride [50-01-1] were dissolved in a mixture of 10 g of water and 52 g of ethanol in order to obtain a 20 wt-% solution. Chlorine content (calculated): 7.4 wt-%

EXAMPLE 7

Flame Retardant Comprising a Molar Ratio of Fe and Cl of 1:3 in Addition to a Nitrogen and Silicon Containing Polymer

[0046] 1 mole of 3-aminopropyltriethoxysilane [919-30-2] was introduced in a 1000 ml 3-necked reaction flask equipped with a reflux condenser and heated to 90-100° C. under stirring (150-200 min.sup.−1). 0.5 mole of 4-hydroxymethylbenzoate [99-76-3] was added as powder within 5-10 minutes. 14 g of nanosilica dispersion (Levasil CS30-824P, Obermeier GmbH, Berleburg, Germany; LOD@120° C./30 min: 68 wt-%) was slowly added under vigorous stirring (400-500 min.sup.−1) within 45 minutes. Reflux of formed ethanol occurs and the reaction mixture gets slightly hazy. After the addition of the nano silica dispersion was finished, the reaction mixtures was stirred vigorously (400-500 min.sup.−1) under reflux for another 15 minutes. Thereafter reflux was switched to distillation and ethanol was distilled off under initial stirring speed (150-200 min.sup.−1). When 39 g of destillate was collected, heating was increased. The reaction mixture was heated to 150° C., where amide formation starts together with distillation of methanol and further kept between 170° C. and 185° C. where amidine condensation takes place. When a total of 74 g of distillate was collected, the reaction mixture was kept at 170° C. and 20 g of tetraethoxysilane [78-10-4] were added under stirring (150-200 min.sup.−1). 226 g of clear reddish and slightly viscous product was obtained which increases viscosity significantly during cooling to room temperature. LOD@120° C./30 min of 82 wt-%. 20 g of product was mixed with a solution of 0.5 g of sodium hydroxide in 19.5 g of water in order to obtain a mixture which was suitable for coating by brushing. The mixture was divided into two parts. The first serves as Example 7 reference. The second part, was mixed with 5 g of product from example 1 and 5 g of product from example 5 in order to obtain Example 7 sample, which was a flame retardant comprising iron (III) dihydroxide benzoate and sucralose with a molar ratio of Fe and CI of about 1:3 in addition to nitrogen and silicon containing polymer. Iron (III) dihydroxide benzoate and Si—OH groups in the polymer can form Fe—O—Si bonds.

EXAMPLE 8

[0047] Flame Retardant Mixtures Comprising a Molar Ratio of Fe and Cl of about 1:3

[0048] Flame retardant mixtures were prepared based on the iron comprising products in Example 1-4 and the chlorine comprising products in Example 5-6. The amounts of products in the different examples have been chosen in order to obtain a molar ratio of Fe and CI of about 1:3. However different mixing ratios were possible and may work as flame retardants. Table 1 below shows the flame retardant mixtures and their composition:

TABLE-US-00001 TABLE 1 Amount Amount Name [g] Component 1 [g] Component 2 Example 8a 5.0 Example 4 10.4 Example 5 Example 8b 5.0 Example 1 4.9 Example 5 Example 8c 5.0 Example 2 17.0 Example 5 Example 8d 5.0 Example 1 5.9 Example 6 Example 8e 5.0 Example 3 3.7 Example 5

Burning Test of Cardboard

[0049] Packaging type cardboard (ca. 300 g/m.sup.2) was coated with the mixtures Example 8a-e and flame tested. The cardboard samples were about 8 cm in width and 20 cm in length. They were coated by brushing two times on the front side, which was exposed to the flame and one time on the backside. Drying was performed for 10 min in an air stream at 80° C.

[0050] Flame conditions: [0051] butane lighter with about 20 mm flame [0052] effect of 60-70 W calculated from butane consumption [0053] vertical position of the sample in relation to the flame [0054] top of flame in contact with cardboard sample for 60 seconds.

[0055] Table 2 shows the results of the flame test (burning test).

TABLE-US-00002 TABLE 2 Weight of burning test samples before and after burning test coated coating after Name raw [g] [g] [g] fire [g] loss [g] loss [%] reference 3.78 3.78 0.00 0.18 3.60 95.2% Example 8a 3.68 4.12 0.44 3.73 0.39 9.5% Example 8b 3.71 4.35 0.64 4.17 0.18 4.1% Example 8c 3.62 3.88 0.26 3.71 0.17 4.4% Example 8d 3.74 3.97 0.23 3.74 0.23 5.8% Example 8e 3.64 5.10 1.46 4.82 0.28 5.5%

[0056] A clear difference between the uncoated reference and the coated samples has been found. All coated samples were self extinguishing within 5 seconds after removal of the butane flame. Weight loss was thoroughly less than 10 wt-% for the coated samples and more than 95 wt-% for the uncoated reference. Most samples show a surprisingly low weight loss of 4-6 wt-%. These examples clearly demonstrate that mixtures of iron containing chemical substances and chlorine containing chemical substances can serve as highly efficient flame retardants on combustible substrates at low mass to mass ratios of flame retardant to substrate.

EXAMPLE 9

[0057] Mixtures Comprising Alkyd Paint and Flame Retardant with a Molar Ratio of Fe and Cl of 1:3

[0058] Alkyd paint “Drygolin oljedekkbeis” (Jotun, Norway) was used for fire retardancy test on cardboard. The alkyd paint was solvent based and white pigmented with a content of volatile organic carbon (VOC)<400 g/I. For the reference sample the paint was used as received.

[0059] Two mixtures of paint and Example 8b have been prepared giving a ratio of flame retardant and paint in dry paint of 10 wt-% and 20 wt-% respectively. The burning test has been performed in a similar way as described in Example 8. Drying time was initially 4 hours at 60° C. and thereafter 80 hours at about 20° C. The 10 wt-% sample has been reproduced after storing the mixture of flame retardant and paint for 2 weeks and with about 50 wt-% of the coating thickness of the initial 10 wt-% sample. Table 3 below shows the results of the burning test:

TABLE-US-00003 TABLE 3 Weight of burning test samples before and after burning test coated coating loss loss Name raw [g] [g] [g] name [g] [%] reference 3.76 5.06 1.30 3.95 1.11 21.9% 20% Example 8b 3.76 5.02 1.26 4.75 0.27 5.4% 10% Example 8b 3.83 5.57 1.74 5.29 0.28 5.0% 10% Example 8b 3.72 4.47 0.75 4.43 0.04 0.9% (stored 2 weeks)

[0060] A clear difference between the coated reference without flame retardant and the coated samples comprising flame retardant has been found. All flame retardant samples comprising flame retardant were self-extinguishing within 5 seconds after removal of the butane flame. Weight loss was around 5 wt-% or lower for the samples comprising flame retardant and more than 20 wt-% for the reference sample without flame retardant. The reference was not self-extinguishing within 5 seconds after removal of the butane flame. The amount of iron in the total sample 10 wt-% Example 8b (stored 2 weeks) is, as calculated from its preparation, 0.018 wt-% and the correspondent chlorine content was 0.034 wt-%. This shows that the disclosed flame retardants can provide flame retardancy at very low loadings.

EXAMPLE 10

[0061] Burning Test of Cardboard with Coating Formulations from Example 7 Reference and Example 7 Sample.

[0062] The burning test has been performed in a similar way as described in Example 8. Drying has been performed for 10 min in an air stream at 80° C. Table 4 below shows the results of the burning test:

TABLE-US-00004 TABLE 4 Weight of burning test samples before and after burning test coated coating after loss Name raw [g] [g] [g] fire [g] [g] loss [%] uncoated 3.78 3.78 0.00 0.18 3.60 95.2% cardboard Example 7 3.69 4.42 0.73 4.06 0.36 8.1% reference Example 7 3.66 4.41 0.75 4.23 0.18 4.1% sample

[0063] A clear difference between the uncoated reference and the coated samples has been found. Furthermore the fire retardancy of the neat polymer on the coated cardboard Example 7 reference was significantly improved by incorporation of flame retardant (Example 7 sample).

EXAMPLE 11

[0064] Coating of Cardboard with Unsaturated Polyester and Burning Test

[0065] 20 g of white pigmented unsaturated polyester gelcoat with a styrene content of 30-35 wt-% and 0.3 g of curing agent have been mixed and applied on cardboard similar to the procedure in Example 8 and 9. The obtained sample was the reference sample Example 11a. Example 11 b has been prepared by mixing 20 g of the same unsaturated polyester, 10 g of the product from Example 1 as iron containing component and 3.8 g 4-chloromethylene styrene as chlorine containing compound and 0.3 g of curing agent. Molar ratio of Fe and CI of about 1:3 for Example 11a. Example 11 b has been prepared by mixing 20 g of the unsaturated polyester, 10 g of the product from Example 1 as iron containing component and 7.5 g 4-chloromethylene styrene as chlorine containing compound and 0.3 g of curing agent. Molar ratio of Fe and CI of about 1:6 for Example 11b. Example 11a and Example 11b have been applied on cardboard in the same way as the reference. Curing time was initially 30 min at 60° C. and thereafter 6 hours at about 20° C. The burning test has been performed in a similar way as described in Example 8. Table 5 below shows the results of the burning test:

TABLE-US-00005 TABLE 5 Weight of burning test samples before and after burning test coated coating after loss Name raw [g] [g] [g] fire [g] [g] loss [%] reference 3.66 4.33 0.67 0.96 3.37 77.8% Example 11a 3.72 4.67 0.95 3.44 1.23 26.3% Example 11b 3.69 4.33 0.64 4.13 0.20 4.6%

[0066] A clear difference between the reference without flame retardant and the samples comprising flame retardant has been found. All samples comprising flame retardant were self extinguishing within 5 seconds after removal of the butane flame. whereas the reference sample burnt completely above the flame application zone.

EXAMPLE 12

[0067] a) Flame retardant mixture forming char in addition to ferric chloride upon heating

[0068] 2 g of flame retardant mixture 8a was heated by an infrared lamp (ca. 1 W/cm.sup.2) and the surface temperature of the flame retardant mixture was measured by an infrared thermometer. Initially the flame retardant mixture had a slightly brownish colour. At 130° C. the surface of the flame retardant mixture become dark and black, at 150° C. the flame retardant mixture had foamed and formed char throughout the heated material.

[0069] b) Heating of the chlorine containing substance of the flame retardant mixture in 12a) alone

[0070] 2 g of sucralose solution as prepared in Example 5 were heated in the same way as the flame retardant mixture in Example 12a). The solution dried, no darkening or char formation was observed upon heating to 150° C. At 200° C. a slightly yellow to brownish colour occurred on top of the dried solution. Still no darkening and no char formation.

EXAMPLE 13

Flame Retardant Mixtures Comprising Ferric Chloride

[0071] In order to prove the flame retardant effect of ferric chloride two formulations 13a) and 13 b) comprising ferric chloride have been prepared and applied and tested as described in Example 8. The composition of the two formulations is given in Table 6.

TABLE-US-00006 TABLE 6 Composition of the two formulations 13 a) and 13 b) Example 13 a): Example 13 b): Mixture of Mixture of 10 g of anhydrous 5 g of 13 a), ferric chloride and 5 g of a 50% aqueous solution of 5 g of water guanidinium chloride and 5 g of a 20% aqueous solution of polyvinylalcohol (fully hydrolyzed, M.sub.w about 80000).

[0072] The results after coating on cardboard and burning test are shown in Table 7 below.

TABLE-US-00007 TABLE 7 Weight of burning test samples before and after burning test of Examples 13 a) and 13 b) raw coated coating after loss Name [g] [g] [g] fire [g] [g] loss [%] uncoated 3.78 3.78 0.00 0.18 3.60 95.2% cardboard Example 13 a) 3.93 5.24 1.31 5.06 0.18 3.4% Example 13 b) 3.75 4.63 0.88 4.34 0.29 6.3%

[0073] The results show clearly that ferric chloride homogenously dispersed on the surface of a combustible material works as flame retardant. The uncoated sample burns almost completely under the same conditions. Therefor ferric chloride can be used as flame retardant. The corrosive properties of ferric chloride might impair its use in some applications. Passivation of ferric chloride by encapsulation or protective layers might hinder corrosion caused by flame retardants containing ferric chloride. No corrosive properties are expected with flame retardants according to the disclosure, when the ferric chloride is formed from non-corrosive precursors after exposure to flames.

[0074] Flame retardants according to the disclosure may be prepared independently from water-based formulations. Flame retardants may comprise one or more iron containing chemical substance and one or more chlorine containing chemical substance as solvent based formulation, as powder, as liquid and as mixture with one or more solid or liquid carriers.

[0075] Flame retardants according to the disclosure can provide flame retardancy at very low loadings such as 0.01 wt-% Fe and 0.01 wt-% Cl of the total weight of a flame retarded material or article. Higher loadings and molar ratios of Fe and Cl which were close to 1:3 such as 0.05 wt-% Fe and 0.1 wt-% Cl may provide improved flame retardancy. Even more improved flame retardancy may be obtained with even higher loadings such as 0.2 wt-% Fe and 0.4 wt-% Cl or with 1.0 wt-% Fe and 2.0 wt-% Cl. Industrial applicability, economical limitations and the chemical composition of ferric chloride, which was 34.4 wt-% Fe and 65.6 wt-% Cl limit the loadings of Fe and Cl in flame retarded substances and materials.