Fire retardant cellulose insulation product and method for making same

Abstract

A fire retardant cellulose insulation material with enhanced smoldering performance and method for making such a material are provided. A method of making a fire retardant cellulose insulation product includes preparing a mixture of MgO and one or more magnesium salts; preparing a cured mixture by curing the mixture for at least 12 hours; preparing a limited hygroscopicity mixture by adding anticaking agents and additives to the cured mixture and grinding the resulting mixture into fine particles; and adding the limited hygroscopicity mixture to cellulosic fibers to form the fire retardant cellulose insulation product.

Description

[0001] FIRE RETARDANT CELLULOSE INSULATION PRODUCT AND METHOD FOR MAKING SAME

[0002] BACKGROUND

[0003] Field of the Disclosure

[0004] The present disclosure relates to fire retardant materials and, more particularly to a borate-free fire retardant cellulose insulation material with enhanced smoldering performance and method for making such a material.

[0005] Description of Related Art

[0006] Phosphoric acid and ammonium salts of phosphoric acid are known to be very effective in inhibiting the combustion of cellulose. The heat treatment of cellulose with phosphoric acid in the presence of certain nitrogen compounds (e.g., ammonia) leads to the formation of cellulose phosphate with flame-resistant properties. The protective effect of ammonium salts is based on the endothermic release of ammonia that leads to cooling of the fire and dilution of the combustion gases. This desired effect, in case of fire, can even occur at high humidity and high indoor temperatures and lead to the ammonia pollution of room air (Gebke S., et al., Molecules, 25(21): 5122 (2020). Accordingly, limit values for ammonia emissions have been progressively reduced according to European Union (EU) regulations (The European Commission, Off. J. Eur. Union, L 166: 1-4 (2016).

[0007] Boron compounds such as boric acid and zinc or sodium borate are also well-known flame retardants for wood and cellulosic products. However, since 2010, boron compounds have been classified by the EU as toxic for reproduction and listed as substance of very high concern in the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulations (Gebke S., et al., Molecules, 25(21): 5122 (2020).

[0008] As such, there exists a need for a borate-free fire retardant product for cellulose insulation with limited or no ammonia emissions when the cellulose is exposed to humid conditions.

[0009] SUMMARY

[0010] The above and other needs are met by aspects of the present disclosure which, in one aspect, provides a method of making a fire retardant cellulose insulation product with enhanced smoldering performance, comprising: preparing a mixture of MgO and one or more magnesium salts; preparing a cured mixture by curing the mixture for at least 12 hours; preparing a limited hygroscopicity mixture by adding anti caking agents and additives to the cured mixture; and adding the limited hygroscopicity mixture to cellulosic fibers to form the fire retardant cellulose insulation product.

[0011] Still another aspect of the present disclosure provides a fire retardant cellulose insulation product, comprising anticaking agents and additives, cellulosic fibers, and a cured mixture of MgO and one or more magnesium salts.

[0012] The present disclosure thus includes, without limitation, the following aspects and embodiments:

[0013] Aspect 1: A method of making a fire retardant cellulose insulation product, comprising:

[0014] (a) preparing a mixture of MgO and one or more magnesium salts;

[0015] (b) preparing a cured mixture by curing the mixture for at least 12 hours;

[0016] (c) preparing a limited hygroscopicity mixture by adding anticaking agents and additives to the cured mixture and grinding the resulting mixture into fine particles; and

[0017] (d) adding the limited hygroscopicity mixture to cellulosic fibers to form the fire retardant cellulose insulation product.

[0018] Embodiment 1: The method of the preceding aspect, wherein preparing the mixture comprises preparing the mixture of MgO and one or more magnesium salts, including MgSO4 and MgCh.

[0019] Embodiment 2: The method of the preceding embodiment, wherein preparing the mixture comprises preparing the mixture including MgO, MgSO4, and MgCh in a ratio of between 1:5:10 and 2:5:10.

[0020] Embodiment 3: The method of any preceding embodiment, or any combination of preceding embodiments, wherein curing the mixture comprises curing the mixture at a temperature of 10-40 °C.

[0021] Embodiment 4: The method of any preceding embodiment, or any combination of preceding embodiments, wherein curing the mixture comprises curing the mixture at a temperature of Embodiment 5: The method of any preceding embodiment, or any combination of preceding embodiments, wherein curing the mixture comprises curing the mixture for 12-30 hours.

[0022] Embodiment 6: The method of any preceding embodiment, or any combination of preceding embodiments, wherein curing the mixture comprises curing the mixture for 18-24 hours.

[0023] Embodiment 7: The method of any preceding embodiment, or any combination of preceding embodiments, wherein adding anticaking agents comprises adding anticaking agents, including hydrophilic / hydrophobic precipitated silica, fumed silica, and organo-modified fumed silica.

[0024] Embodiment 8: The method of any preceding embodiment, or any combination of preceding embodiments, wherein adding the limited hygroscopicity mixture to cellulosic fibers comprises adding the limited hygroscopicity mixture to cellulosic fibers comprising hydroxy ethyl cellulose, hydroxy propyl cellulose, hydroxy isopropyl cellulose, kaolin coated cellulose, or a combination thereof.

[0025] Embodiment 9: The method of any preceding embodiment, or any combination of preceding embodiments, wherein adding additives comprises adding additives, including one or more corrosion inhibitors.

[0026] Embodiment 10: The method of any preceding embodiment, or any combination of preceding embodiments, wherein preparing the limited hygroscopicity mixture comprises preparing the limited hygroscopicity mixture having a moisture content of 5-10 %.

[0027] Embodiment 11: The method of any preceding embodiment, or any combination of preceding embodiments, wherein preparing the limited hygroscopicity mixture comprises preparing the limited hygroscopicity mixture having a particle size of 50-2000 pm.

[0028] Embodiment 12: The method of any preceding embodiment, or any combination of preceding embodiments, wherein adding the limited hygroscopicity mixture to the cellulosic fibers comprises adding the limited hygroscopicity mixture to the cellulosic fibers such that the fire retardant cellulose insulation product comprises 0.02-0.2 % anticaking agents by weight. Embodiment 13: The method of any preceding embodiment, or any combination of preceding embodiments, wherein adding the limited hygroscopicity mixture to the cellulosic fibers comprises adding the limited hygroscopicity mixture to the cellulosic fibers such that the fire retardant cellulose insulation product comprises 85-95 % cellulosic fibers by weight.

[0029] Embodiment 14: The method of any preceding embodiment, or any combination of preceding embodiments, wherein adding the limited hygroscopicity mixture to the cellulosic fibers comprises adding the limited hygroscopicity mixture to the cellulosic fibers such that the fire retardant cellulose insulation product comprises between 0.1 -0.2 % additives by weight.

[0030] Aspect 2: A fire retardant cellulose insulation product, comprising anticaking agents and additives, cellulosic fibers, and a cured mixture of MgO and one or more magnesium salts.

[0031] Embodiment 15: The product of the above aspect, wherein the one or more magnesium salts includes MgSC>4 and MgCh.

[0032] Embodiment 16: The product of the preceding embodiment, wherein the cured mixture comprises MgO, MgSO4, and MgCh in a ratio of between 1:5:10 and 2:5:10.

[0033] Embodiment 17: The product of any preceding embodiment, or any combination of preceding embodiments, wherein the anticaking agents include hydrophilic / hydrophobic precipitated silica, fumed silica, and organomodified fumed silica.

[0034] Embodiment 18: The product of any preceding embodiment, or any combination of preceding embodiments, wherein the cellulosic fibers comprise hydroxy ethyl cellulose, hydroxy propyl cellulose, hydroxy isopropyl cellulose, or a combination thereof.

[0035] Embodiment 19: The product of any preceding embodiment, or any combination of preceding embodiments, wherein the additives include one or more corrosion inhibitors. Embodiment 20: The product of any preceding embodiment, or any combination of preceding embodiments, wherein the cured mixture, the anticaking agents, and the additives form a limited hygroscopicity mixture having a moisture content of 5-10 %.

[0036] Embodiment 21: The product of any preceding embodiment, or any combination of preceding embodiments, wherein the cured mixture, the anticaking agents, and the additives form a limited hygroscopicity mixture having a particle size of 50-2000 pm.

[0037] Embodiment 22: The product of any preceding embodiment, or any combination of preceding embodiments, wherein the fire retardant cellulose insulation product comprises 0.05-0.5 % anticaking agents by weight.

[0038] Embodiment 23: The product of any preceding embodiment, or any combination of preceding embodiments, wherein the fire retardant cellulose insulation product comprises SO- 95 % cellulosic fibers by weight.

[0039] Embodiment 24: The product of any preceding embodiment, or any combination of preceding embodiments, wherein the fire retardant cellulose insulation product comprises 0.1-0.2 % additives by weight.

[0040] Embodiment 25: The product of any preceding embodiment, or any combination of preceding embodiments, wherein the fire retardant cellulose insulation product has a critical radiant flux <0.12 W / cm2

[0041] These and other features, aspects, and advantages of the present disclosure will be apparent from a reading of the following detailed description. The present disclosure includes any combination of two, three, four, or more features or elements set forth in this disclosure, regardless of whether such features or elements are expressly combined or otherwise recited in a specific embodiment description herein. This disclosure is intended to be read holistically such that any separable features or elements of the disclosure, in any of its aspects and embodiments, should be viewed as intended, namely, to be combinable, unless the context of the disclosure clearly dictates otherwise.

[0042] It will be appreciated that the summary herein is provided merely for purposes of summarizing some example aspects so as to provide a basic understanding of the disclosure. As such, it will be appreciated that the above described example aspects are merely examples and should not be construed to narrow the scope or spirit of the disclosure in any way. It will be appreciated that the scope of the disclosure encompasses many potential aspects, some of which will be further described below, in addition to those herein summarized. Further, other aspects and advantages of such aspects disclosed herein will become apparent from the following detailed description taken in conjunction with accompanying drawings which illustrate, by way of example, the principles of the described aspects.

[0043] BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

[0044] Having thus described the disclosure in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0045] FIG.1 schematically illustrates a flowchart associated with a method for making a borate-free fire retardant cellulose insulation material with enhanced smoldering performance, according to one aspect of the present disclosure.

[0046] DETAILED DESCRIPTION OF THE DISCLOSURE

[0047] The present disclosure now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all aspects of the disclosure are shown. Indeed, the disclosure may be embodied in many different forms and should not be construed as limited to the aspects set forth herein; rather, these aspects are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0048] The present disclosure generally pertains to fire retardant products and, more particularly to fire retardant cellulose insulation products with enhanced smoldering performance and method for making such products. As used herein, smoldering performance refers to a measure of how well a material resists smoldering, and smoldering refers to the process of burning slowly with smoke but no flame. The fire retardant cellulose insulation product of the present disclosure is a borate-free fire retardant product, e.g., a powder, for cellulose insulation with limited or no ammonia emissions when the cellulose is exposed to humid conditions. As ammonia emissions are created by common fire retardant products based on ammonium phosphates, a need was identified to develop a borate-free, ammonium- free fire retardant product to replace the current, commercially available fire retardant material (boric acid / magnesium sulfate mix). The fire retardant cellulose insulation product of the present disclosure provides an effective and relatively less expensive insulation product.

[0049] In some aspects, the present disclosure is directed to a method of making a fire retardant cellulose insulation product, comprising:

[0050] (a) preparing a mixture of MgO and one or more magnesium salts;

[0051] (b) preparing a cured mixture by curing the mixture for at least 12 hours;

[0052] (c) preparing a limited hygroscopicity mixture by adding anticaking agents and additives to the cured mixture and grinding the resulting mixture into fine particles; and

[0053] (d) adding the limited hygroscopicity mixture to cellulosic fibers to form the fire retardant cellulose insulation product.

[0054] In some embodiments, preparing the mixture comprises preparing the mixture of MgO and one or more magnesium salts, including MgSO4 and MgCh.

[0055] In some embodiments, preparing the mixture comprises preparing the mixture including MgO, MgSO4, and MgCh in a ratio of between 1:5:10 and 2:5:10.

[0056] In some embodiments, the mixture comprises curing the mixture at a temperature of 10-40 °C. In some embodiments, curing the mixture comprises curing the mixture at a temperature of 25 °C.

[0057] In some embodiments, curing the mixture comprises curing the mixture for 12-30 hours. In some embodiments, curing the mixture comprises curing the mixture for 18-24 hours.

[0058] In some embodiments, adding anti caking agents comprises adding anticaking agents, including hydrophilic / hydrophobic precipitated silica, fumed silica, and organo-modified fumed silica.

[0059] In some embodiments, adding the limited hygroscopicity mixture to cellulosic fibers comprises adding the limited hygroscopicity mixture to cellulosic fibers comprising hydroxy ethyl cellulose, hydroxy propyl cellulose, hydroxy isopropyl cellulose, kaolin coated cellulose or a combination thereof.

[0060] In some embodiments, adding additives comprises adding additives, including one or more corrosion inhibitors.

[0061] In some embodiments, preparing the limited hygroscopicity mixture comprises preparing the limited hygroscopicity mixture having a moisture content of 5-10 %.

[0062] In some embodiments, preparing the limited hygroscopicity mixture comprises preparing the limited hygroscopicity mixture having a particle size of 0.5-2000 pm. In some embodiments, adding the limited hygroscopicity mixture to the cellulosic fibers comprises adding the limited hygroscopicity mixture to the cellulosic fibers such that the fire retardant cellulose insulation product comprises 0.05-0.5 % anticaking agents by weight.

[0063] In some embodiments, adding the limited hygroscopicity mixture to the cellulosic fibers comprises adding the limited hygroscopicity mixture to the cellulosic fibers such that the fire retardant cellulose insulation product comprises 80-95 % cellulosic fibers by weight.

[0064] In some embodiments, adding the limited hygroscopicity mixture to the cellulosic fibers comprises adding the limited hygroscopicity mixture to the cellulosic fibers such that the fire retardant cellulose insulation product comprises between 0.1 -0.2 % additives by weight.

[0065] The above methods provide a fire retardant cellulose insulation product with optimum fire retardant properties, limited hygroscopicity, and storage stability. Particular factors in the manufacturing of the fire retardant cellulose insulation product of the present disclosure, affecting fire performance of the product, include:

[0066] Particle size of the final product

[0067] The particle size of the final formulation is of material importance and related to the final fire performance of the treated cellulose. To prepare the limited hygroscopicity mixture described herein, anticaking agents and additives were added to the cured mixture and the resulting mixture was ground into fine particles (<100 pm). A cellulose shredder or chemical grinder may be used to grind the flame retardant mixture.

[0068] The addition levels of Mg salts

[0069] Increased addition levels / ratios of Mg salts may enhance the smoldering performance of the cellulose at the end of the fire tests.

[0070] Accordingly, in some aspects, the present disclosure provides a fire retardant cellulose insulation product, comprising anticaking agents and additives, cellulosic fibers, and a cured mixture of MgO and one or more magnesium salts.

[0071] In some embodiments, one or more magnesium salts includes MgSCfi and MgCh.

[0072] In some embodiments, the cured mixture comprises MgO, MgSO4, and MgCh in a ratio of between about 1:5: 10 and 2:5:10.

[0073] In some embodiments, the anticaking agents include hydrophilic / hydrophobic precipitated silica, fumed silica, and organo-modified fumed silica. In some embodiments, the cellulosic fibers comprise hydroxy ethyl cellulose, hydroxy propyl cellulose, hydroxy isopropyl cellulose, or a combination thereof.

[0074] In some embodiments, the additives include one or more corrosion inhibitors. The corrosion inhibitor may include but are is limited to, sodium selenite, sodium stearate, sodium benzoate, sodium fluoride, sodium phosphate, magnesium phosphate, benzotriazole-5- carboxcylic acid, benzotriazole, 1,8-napthalaldehydic acid, octadecylphosphonic acid, sodium dodecyl sulfonate (SDBS), Wintrol® BBT-25Na, Wintrol® BBT, Wintrol® THT-T, Wintrol® THT-35PG, Wintrol® THT-50K, Wintrol® SAM-H90, Wintrol SB 25Na, Wintrol® SAM-H38Na, Wintrol® SAM-H40(OS), Wintrol® SAM-B90, berberine, pyrrolidine riccione, catechin, lysergic acid, carmine, fast green, aniline, triethanolamine, p- chloroaniline, p-nitroaniline, p-methoxy aniline, p-methylaniline, sodium silicate, or a combination of the above.

[0075] In some embodiments, the cured mixture, the anticaking agents, and the additives form a limited hygroscopicity mixture having a moisture content of 5-10 %.

[0076] In some embodiments, the cured mixture, the anticaking agents, and the additives form a limited hygroscopicity mixture having a particle size of 0.5-2000 pm.

[0077] In some embodiments, the fire retardant cellulose insulation product comprises 0.05- 0.5 % anti caking agents by weight.

[0078] In some embodiments, the fire retardant cellulose insulation product comprises 80-95 % cellulosic fibers by weight.

[0079] In some embodiments, the fire retardant cellulose insulation product comprises 0.1- 0.2 % additives by weight.

[0080] In some embodiments, the fire retardant cellulose insulation product has a critical radiant flux <0.12 W / cm2

[0081] EXAMPLES

[0082] A limited hygroscopicity mixture of flame retardant was produced. The product was cured for 24 h at 25 °C before the anti caking agents and additives were added. The flame retardant product comprised 20-30% MgO. The product was ground in a cellulose shredder and mixed with the cellulose to produce the fire retardant cellulose insulation which comprises 85% cellulosic fibers by weight. The cellulose insulation was blown in a blowing machine to product low density cellulose insulation. A sample of the blown cellulose insulation was tested in Small Scale Electric Radiant Panel according to CAN / ULC-S703-09 standard for cellulose fiber insulation. The critical radiant flux of the fire retardant cellulose insulation is <0.12 W / cm2.

[0083] The product was also tested according to EN ISO 11925-22020 Ignitability Single Flame Source at two densities (28-48 kg / m3). The product met the criteria with a flame length <15 cm and it also stopped smoldering within 30 seconds after the removal of the flame from the cellulose insulation.

[0084] Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these disclosed embodiments pertain having the benefit of the teachings presented in the foregoing descriptions. Therefore, it is to be understood that embodiments of the invention are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the invention. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and / or functions, it should be appreciated that different combinations of elements and / or functions may be provided by alternative embodiments without departing from the scope of the disclosure. In this regard, for example, different combinations of elements and / or functions than those explicitly described above are also contemplated within the scope of the disclosure. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0085] As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes”, and / or “including”, when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Therefore, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

Claims

THAT WHICH IS CLAIMED:

1. A method of making a fire retardant cellulose insulation product, comprising:(a) preparing a mixture of MgO and one or more magnesium salts;(b) preparing a cured mixture by curing the mixture for at least 12 hours;(c) preparing a limited hygroscopicity mixture by adding anticaking agents and additives to the cured mixture to form a resulting mixture and grinding the resulting mixture into fine particles; and(d) adding the fine particles of the limited hygroscopicity mixture to cellulosic fibers to form the fire retardant cellulose insulation product.

2. The method of claim 1, wherein preparing the mixture comprises preparing the mixture of MgO and one or more magnesium salts including, MgSO4 and MgCh.

3. The method of claim 2, wherein preparing the mixture comprises preparing the mixture including MgO, MgSO4, and MgCh in a ratio of between 1:5:10 and 2:5:10.

4. The method of claim 1, wherein curing the mixture comprises curing the mixture at a temperature of 10 -40 °C.

5. The method of claim 1, wherein curing the mixture comprises curing the mixture at a temperature of 25 °C.

6. The method of claim 1, wherein curing the mixture comprises curing the mixture for 12-30 hours.

7. The method of claim 1, wherein curing the mixture comprises curing the mixture for 18-24 hours.

8. The method of claim 1, wherein adding anticaking agents comprises adding anticaking agents, including hydrophilic / hydrophobic precipitated silica, fumed silica, and organo- modified fumed silica.

9. The method of claim 1, wherein adding the limited hygroscopicity mixture to cellulosic fibers comprises adding the limited hygroscopicity mixture to cellulosic fibers comprising hydroxy ethyl cellulose, hydroxy propyl cellulose, hydroxy isopropyl cellulose, kaolin coated cellulose, or a combination thereof.

10. The method of claim 1, wherein adding additives comprises adding additives, including one or more corrosion inhibitors.

11. The method of claim 1, wherein preparing the limited hygroscopicity mixture comprises preparing the limited hygroscopicity mixture having a moisture content of 5-10 %.

12. The method of claim 1, wherein preparing the limited hygroscopicity mixture comprises preparing the limited hygroscopicity mixture having a particle size of 0.5-2000 pm.

13. The method of claim 1, wherein adding the limited hygroscopicity mixture to the cellulosic fibers comprises adding the limited hygroscopicity mixture to the cellulosic fibers such that the fire retardant cellulose insulation product comprises 0.05-0.5 % anticaking agents by weight.

14. The method of claim 1, wherein adding the limited hygroscopicity mixture to the cellulosic fibers comprises adding the limited hygroscopicity mixture to the cellulosic fibers such that the fire retardant cellulose insulation product comprises 80-95 % cellulosic fibers by weight.

15. The method of claim 1, wherein adding the limited hygroscopicity mixture to the cellulosic fibers comprises adding the limited hygroscopicity mixture to the cellulosic fibers such that the fire retardant cellulose insulation product comprises between 0.1-0.2 % additives by weight.

16. A fire retardant cellulose insulation product, comprising anticaking agents and additives, cellulosic fibers, and a cured mixture of MgO and one or more magnesium salts.

17. The product of claim 16, wherein the one or more magnesium salts includes MgSO4 and MgCl2.

18. The product of claim 16, wherein the cured mixture comprises MgO, MgSC and MgCh in a ratio selected from 1:5:10 and 2:5:10.

19. The product of claim 16, wherein the anti caking agents include hydrophilic / hydrophobic precipitated silica, fumed silica, and organo-modified fumed silica.

20. The product of claim 16, wherein the cellulosic fibers comprise hydroxy ethyl cellulose, hydroxy propyl cellulose, hydroxy isopropyl cellulose, kaolin coated cellulose, or a combination thereof.

21. The product of claim 16, wherein the additives include one or more corrosion inhibitors.

22. The product of claim 16, wherein the cured mixture, the anticaking agents, and the additives form a limited hygroscopicity mixture having a moisture content of 0.5-10 %.

23. The product of claim 16, wherein the cured mixture, the anticaking agents, and the additives form a limited hygroscopicity mixture having a particle size of 0.5-2000 pm.

24. The product of claim 16, wherein the fire retardant cellulose insulation product comprises 0.05-0.5 % anticaking agents by weight.

25. The product of claim 16, wherein the fire retardant cellulose insulation product comprises 80-95 % cellulosic fibers by weight.

26. The product of claim 16, wherein the fire retardant cellulose insulation product comprises 0.1-0.2 % additives by weight.

27. (New) The product of claim 16, which has a critical radiant flux <0.12 W / cm2

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