GB2360298A

GB2360298A - A method of manufacturing mineral wool to improve the fire-rating thereof

Info

Publication number: GB2360298A
Application number: GB0006604A
Authority: GB
Inventors: Brian James
Original assignee: Firespray International Ltd
Current assignee: Firespray International Ltd
Priority date: 2000-03-17
Filing date: 2000-03-17
Publication date: 2001-09-19
Anticipated expiration: 2020-03-17
Also published as: GB2360298B; GB0006604D0

Abstract

In a method for manufacturing mineral wool, mineral wool fibres (1) are impregnated with an intumescent material (5) during manufacture of the mineral wool so that the fire protection capability of the mineral wool is enhanced.

Description

2360298 1 A Method of Manufacturing Mineral Wool to Improve the

Fire-rating thereof The present invention relates to the manufacture of mineral wool from mineral wool fibres.

Fire-rated mineral wool is commonly used as an insulator for structures, such as ducts, to protect the structures against fire. However, binders in the mineral wool, which hold the fibres of the mineral wool together, often break down in a relatively short period of time under the high temperatures caused by fire, so that the ability of the mineral wool to resist fire is limited. Although the fire resistance of mineral wool can be improved by adjusting the density, quantity and/or type of binder used, it is still necessary to provide a relatively large amount of mineral wool to achieve sufficient fire protection. For example, a 100 min thickness of mineral wool might be required to achieve a 2 hour insulation rating, i.e. the temperature outside the mineral wool will not exceed 140 0 C + ambient temperature when the temperature on the inside of the duct around which the mineral wool is placed is approximately 1000 0 C (based on test criteria set out in British Standard 476 Part 24, ISO 6944).

As an alternative, attempts have been made to avoid the use of mineral wool altogether by spraying the structures with an intumescent material, i.e. a material which swells as a result of heat, to protect the structures against fire. However, it has been found that intumescent materials generally intumesce at relatively high temperatures, so that the material from which the structures are manufactured, e.g. steel, heats up more quickly than the intumescent material, with the result that the intumescent material falls away from the surface of the structures before intumescence takes place.

2 Further attempts have been made to protect structures against fire by spraying mineral wool with an intumescent material and using the sprayed mineral wool to protect the structures. However, such attempts have had limited success due to the difficulty in impregnating the mineral wool with the intumescent material.

An object of the present invention is to overcome the above disadvantages so that the fire protection characteristics, i.e. fire-rating, of mineral wool can be improved.

Claims

The invention provides a method of manufacturing mineral wool as claimed in Claim 1. The invention also provides a mineral wool as claimed in Claim 19 and a method of protecting a structure against fire as claimed in Claim 20. In a preferred embodiment of the invention the intumescent material is sprayed onto the fibres. In a further preferred embodiment of the invention a binder is also applied to the fibres during the manufacturing process. The binder is preferably applied to the fibres prior to the application of the intumescent material. In a preferred embodiment the binder is sprayed onto the fibres. In a preferred embodiment of the invention the intumescent material is distributed evenly throughout the fibres. In a further preferred embodiment the intumescent material is distributed by a spreader. The spreader is preferably a pendulum spreader. In a preferred embodiment the fibres are compressed following distribution of the intumescent material. In a fimlher preferred embodiment of the invention the fibres are cured. The fibres are preferably crimped following curing. In a preferred embodiment a pigment is added to the fibres. The fibres are preferably made of limestone. The intumescent material is preferably an organic-based polymer with intumescent additives. In a preferred embodiment of the 3 invention a thickness of between 1 min and 5 min of intumescent material is applied per 50 min thickness of fibres. In a preferred embodiment of the invention the intumescent material intumesces at a temperature above the curing temperature. The intumescent material preferably intumesces above 3 00 "C. Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic view of the steps involved in the method according to the invention, and Figure 2 is an expanded sectional view of mineral wool impregnated with an intumescent material manufactured in accordance with the invention. In Figure 1, mineral wool fibres 1 produced from a mineral, such as limestone, are fed onto a conveyor belt 2, travelling in the direction of arrow 3, at a first end 2a. The process by which the mineral is converted to mineral wool fibres is a standard technique and will not be described here. As the fibres 1 pass along the conveyor belt 2, a binder 4 is sprayed onto the fibres 1 in a region A of the conveyor belt 2 in a known manner. An intumescent material 5, such as an organic-based polymer with intumescent additives, is sprayed onto the fibres 1 in a region B of the conveyor belt 2. The amount of intumescent material applied to the fibres may be adjusted as required between a thickness of 1 mm and 5 min per 50mm thickness of mineral wool fibres, depending upon the fire rating required. In the present embodiment up to 15 layers of intumescent material, approximately 0.2 min thick, are applied to the fibres. At a second end 2b of the conveyor belt 2 the fibres 1 fall downwards into a pendulum spreader 6. A top end 6a of the pendulum spreader is arranged adjacent the end 2b of the conveyor belt 2 so that the pendulum spreader 6 is arranged substantially 4 perpendicular to the conveyor belt 2. A bottom end 6b of the pendulum spreader 6 is arranged adjacent a first end 7a of a further conveyor belt 7 so that the pendulum spreader 6 is also substantially perpendicular to the conveyor belt 7. The fibres 1 are folded in the pendulum spreader 6 in a known manner. The folding enables the intumescent material to be spread evenly throughout the fibres 1. The fibres 1 emerge from the pendulum spreader 6 and are laid on the conveyor belt 7 to form a mineral wool slab 11. Figure 2 shows a section through the mineral wool slab 1 impregnated with intumescent material 5. The mineral wool slab 11 passes along the conveyor belt 7 in the direction of arrow 8 and is subsequently compressed and cut to the required size. The cut mineral wool slab 11 is then placed in an oven (not shown) to cure the binder in the slab 11. Curing takes place at a temperature of approximately 250'C. It is important, therefore, that the temperature at which the intumescent material 5 intumesces exceeds this temperature. For example, the intumescence temperature of the material could be 300'C. The mineral wool impregnated with the intumescent material can then be applied to a structure to be protected from fire, for example, by wrapping the mineral wool around the structure, or by attaching it to the structure in some suitable way. Intumescent materials expand by up to 30 times their original thickness as a result of intumescence. The impregnation of the intumescent material into the mineral wool during manufacture results in greatly improved insulation characteristics of the mineral wool, since the intumescent material intumesceses into the gaps between the mineral wool fibres to form a solid barrier, preventing heat transfer through the wool. As a result the thickness of mineral wool required for effective insulation is reduced by up to 50%, resulting in a considerable saving in cost and material. The reduction in the physical bulk of the material required also simplifies installation of the material on the duct to be insulated. Although the binder in the mineral wool still disintegrates as a result of the high temperature, the intumescent material acts as a substitute binder following intumescence. In the embodiment described above the binder applied to the mineral wool fibres must be cured. It will be appreciated that alternative binders which do not require curing may be used, so that the curing process can be omitted. Alternatively, the binder may be omitted completely, thereby removing the need for the curing process. Similarly, the mineral wool could additionally be crimped during the manufacturing process so that the fibres of the wool are held together more tightly. It is also possible to include a pigmentation step in the manufacturing process. By adding a pigment to the wool, the wool could be identified, for example, as being fire-rated. Different pigments could be used to indicate different degrees of fire-rating. If the crimping and curing processes are included, these processes could be carried out simultaneously or sequentially. In the embodiment described above the binder is applied to the mineral wool fibres prior to the application of the intumescent material. However, it would be possible to apply the binder to the fibres after the intumescent material. Alternatively, the binder and intumescent material could be applied simultaneously to the fibres. Although the spreader used in the embodiment described above is a pendulum spreader, it would be possible to use any other suitable spreader that spreads the intumescent material evenly throughout the fibres. Similarly, although the intumescent material and mineral wool used in the embodiment described above are an organic-based polymer with intumescent additives and limestone respectively, it is of course possible to use any other suitable materials, such as a water-based acrylic with intumescent additives for the intumescent material. 6 Claims:

1. A method of manufacturing mineral wool from mineral wool fibres, wherein the fibres are impregnated with an intumescent material during manufacture of the mineral wool, so as to enhance the fire protection capability of the mineral wool.

2. A method as claimed in Claim 1, wherein the intumescent material is sprayed onto the fibres.

3. A method as claimed in Claim 1 or 2, wherein a binder is applied to the fibres during manufacturing.

4. A method as claimed in Claim 3, wherein the binder is applied to the fibres prior to application of the intumescent material.

5. A method as claimed in Claim 3 or 4, wherein the binder is sprayed onto the fibres.

6. A method as claimed in any one of the preceding claims, wherein the intumescent material is distributed evenly throughout the fibres.

7. A method as claimed in Claim 6, wherein the intumescent material is distributed by a spreader.

8. A method as claimed in Claim 7, wherein the spreader is a pendulum spreader.

9. A method as claimed in Claim 6, 7 or 8, wherein the fibres are compressed following distribution of the intumescent material.

10. A method as claimed in any one of the preceding claims, wherein the fibres are cured.

7

11. A method as claimed in Claim 10, wherein the fibres are crimped following curing.

12. A method as claimed in any one of the preceding claims, wherein a Pigment is applied to the fibres.

13. A method as claimed in any one of the preceding claims, wherein the fibres of the mineral wool are made of limestone.

14. A method as claimed in any one of the preceding claims, wherein the intumescent material is an organic-based polymer with intumescent additives.

15. A method as claimed in any one of the preceding claims, wherein a thickness of between 1 min and 5 mm of intumescent material is applied per 50 min of fibres.

16. A method as claimed in any one of Claims 10 to 15, wherein the intumescent material intumesces at a temperature above the curing temperature.

17. A method as claimed in Claim 16, wherein the intumescent material intumesces above 30TC.

18. A method of manufacturing mineral wool for fire protection substantially as herein described with reference to the accompanying drawings.

19. Mineral wool manufactured according to the method as claimed in any one of the preceding claims.

20. A method of fire protecting a structure comprising applying a mineral wool as claimed in Claim 18 to the structure.

Amendments to the claims have been filed as follows Claims:

8. A method as claimed in Claim 7, wherein the spreader is a pendulum spreader. 9. A method as claimed in Claim 6, 7 or 8, wherein the fibres are compressed following distribution of the intumescent material.

Ok 11. A method as claimed in Claim 10, wherein the fibres are crimped following curing.

14. A method as claimed in any one of the preceding claims, wherein the inturnescent material is an organic-based polymer with intumescent additives.

15. A method as claimed in any one of the preceding claims, wherein a thickness of between 1 mm and 5 nun of intumescent material is applied per 50 mm thickness of fibres.