MINERAL WOOL PRODUCT

Abstract

A mineral wool batt for use as a plant growth medium, particularly in applications for growing vegetation (including plants) in which water retention and/or the avoidance of water run-off is of interest. The mineral wool batt has an absorbent layer which comprises needled mineral wool fibres; superabsorbent particles in the absorbent layer may be sandwiched between a denser upper and/or lower barrier layer(s) which assist in preventing their escape.

Claims

1.-15. (canceled)

16. A method of growing vegetation at an installation selected from a green roof, a landscape, a sports facility, a golf course and an urban garden, the method comprising: providing at the installation a growing medium comprising a mineral wool batt which has an average density of at least 20 kg/m.sup.3 and which comprises needled mineral wool fibres; and growing the vegetation on the growth medium at the installation.

17. The method of claim 16, in which the vegetation is grown from an exposed surface directly from the mineral wool batt.

18. The method of claim 16, in which the vegetation is grown through a growing medium covering partially or substantially the mineral wool batt.

19. The method of claim 18, in which the growing medium is selected from sand and soil.

20. The method of claim 16, in which the mineral wool batt is installed at its desired site prior to seeding or planting of the vegetation.

21. The method of claim 16, further comprising: using the mineral wool batt is as a support for initial growing of the vegetation under controlled or favorable conditions; and subsequently transferring the mineral wool batt incorporating pre-grown vegetation to the installation.

22. The method of claim 16, in which the mineral wool batt comprises at least one of: a fertilizer; an herbicide; a growing aid; and a seed.

23. The method of claim 16, in which the mineral wool batt is substantially devoid of binder.

24. The method of claim 16, in which the mineral wool batt is free of superabsorbent particles.

25. The method of claim 16, in which the mineral wool batt consists essentially of needled mineral wool fibres.

26. The method of claim 16, in which the nominal thickness of the mineral wool batt is in the range 10 to 120 mm.

27. The method of claim 16, in which the average density of the mineral wool batt is 200 kg/m.sup.3.

28. The method of claim 16, in which the mineral fibers are stone wool.

29. The method of claim 16, in which the mineral fibers are glass wool.

30. The method of claim 16, in which the mineral wool batt has at least one of or any combination of the following characteristics: A t0 initial water retention of at least 6.5 times its own weight; A t0 initial water content of at least 70%; A cycle 4, cycled water retention after 2 days of at least 2.5 times its own weight; A cycle 4, cycled water retention after 2 days of at least 75%; A VSE water content after vacuum of 10 cm of at least 70%; A WOK water content after 30 minutes of at least 65%.

31. A method of growing vegetation at an installation selected from a green roof, a landscape, a sports facility, a golf course and an urban garden, the method comprising: providing at the installation a mineral wool batt which has an average density of at least 20 kg/m.sup.3, which is substantially devoid of binder, which is free of superabsorbent particles, and which comprises needled mineral wool fibres; and growing the vegetation from an exposed surface directly from the mineral wool batt at the installation.

32. A method of growing vegetation at an installation selected from a green roof, a landscape, a sports facility, a golf course and an urban garden, the method comprising: providing at the installation a growing medium comprising a mineral wool batt which has an average density of at least 20 kg/m.sup.3, which is substantially devoid of binder, which is free of superabsorbent particles, and which comprises needled mineral wool fibres; and growing the vegetation through a growing medium selected from sand and soil, the growing medium covering partially or substantially the mineral wool batt.

Description

[0035] Non-limiting examples of the invention are described below with reference to:

[0036] FIG. 1 which is a cross-section of one embodiment of a mineral wool batt;

[0037] FIG. 2 which is a cross-section of another embodiment of a mineral wool batt; and

[0038] FIGS. 3 to 7 which are schematic representations of stages in preferred manufacturing techniques for the batt of FIG. 2.

[0039] The mineral wool batt 10 shown in FIG. 1 comprises an absorbent layer 11 comprising superabsorbent particles 12 held between fibres of needled mineral wool. In this embodiment, the superabsorbent particles 12 are distributed substantially evenly over the thickness of the mineral wool batt.

[0040] The mineral wool batt 10 shown in FIG. 2 comprises an absorbent layer in the form of a core 11 comprising super absorbent particles 12 sandwiched between an upper barrier layer 13 and a lower barrier layer 14. The superabsorbent particles 12 are retained between the interstices of the fibres of the absorbent layer or core 11 (as in FIG. 1) and also prevented from escaping from the major surface of the batt by the upper 13 and lower 14 barrier layers of mineral wool which have a density greater than that of the core.

[0041] The mineral wool batt 10 may be manufactured using the following steps:

[0042] In an initial step, represented in FIG. 3, a semi-finished mineral wool batt 21 is provided by assembling mineral wool fibres in to a blanket. The semi-finished mat may be provided by folding layers of mineral wool fibres using a reciprocating motion of a pendulum 22 so that fibres are evenly distributed in several layers and subsequently compressing this blanket to an initially desired density, for example in the range of 40 to 140 kg/m.sup.3. The semi-finished batt 21 is free of binder, no binder having been applied to the fibres or to the blanket.

[0043] In a subsequent step, represented in FIG. 4, a desired quantity of superabsorbent particles 12 is distributed at an upper surface of the semi-finished mineral wool batt 21 via a nozzle 32 as the batt 21 advances along a production line. Preferably, the superabsorbent particles are distributed substantially evenly over substantially the entire upper surface of the batt 21; a border strip of, for example, about 5-15 mm along each side edge of the upper surface of the batt 21 may nevertheless remain substantially free of superabsorbent particles so as to avoid spillage of the superabsorbent particles during their applicant and/or during subsequent operations.

[0044] Once the superabsorbent particles have been distributed at the upper surface of the batt 21, a moving covering belt (not shown) is applied to cover the upper surface and the superabsorbent particles and travels with the batt to the next step in the production process so at to minimise fall off of the superabsorbent particles from the batt 21. The covering belt may press some of the superabsorbent particles in to an upper surface of the batt 21.

[0045] The semi-finished batt 21 then travels to a needling station represented in FIG. 5 at which, just after separation of the covering belt (not shown) from the upper surface of the semi-finished mineral wool batt 21, a series of upper surface needles 43 are reciprocated up and down through the upper surface of the semi-finished mineral wool batt 21. At the same time, a series of lower surface needles 44 are reciprocated up and down through the lower surface of the semi-finished mineral wool batt 21. The effects of the needling action are: [0046] To push the superabsorbent particles 12 in to the core 11 of the mineral wool batt and to needle the fibres between each other (which increases the stability of the mineral wool batt); [0047] To increase the density of the core 11 of the mineral wool batt 21, preferably to a density in the range 30 to 120 kg/m.sup.3 or in the range 30 to 160 kg/m.sup.3; [0048] To cause the super absorbent particles 12 to be trapped between fibres at the core 11 of the mineral wool batt; [0049] To create an upper barrier layer 13 and a lower barrier layer 14, each of which is has a higher density than the core 11 of the batt and each of which provides increased resistance to escape of superabsorbent particles 12 from the batt 21.

[0050] The density of the upper barrier layer 13 and a lower barrier layer 14 may be in the range 50 to 140 kg/m.sup.3 or in the range 50 to 180 kg/m.sup.3. The needling operation may be conducted in a number of sub-steps. For example: [0051] A first sub-step in which (a) the upper surface needles are used with long strokes to push the superabsorbent particles in to the core or the batt 21 and (b) the lower surface needles 44 are used with short strokes to create the higher density needled lower barriers lay 14; and [0052] A second sub-step in which, once the superabsorbent particles have been pushed towards the core 11 of the batt 21, the upper surface needles 43 are used with short strokes to create the higher density needled upper barriers lay 13.

[0053] The mineral wool batt comprising superabsorbent particles may then be further processed and/or packaged (preferably under compression) in to rolls or blocks or even cut in to flocks ready for transportation and use.

[0054] In the FIGS. 4 and 5 arrangement, a pendulum 22 (or equivalent arrangement) is used to superimpose initial layers of fibres, for example by folding, to form a semi-finished mineral wool batt 21 and the superabsorbent particles are initially distributed at an upper surface of this assembled semi-finished mineral wool batt 21. Alternatively, or additionally, superabsorbent particles may be distributed on an initial layer of fibres, for example before a pendulum, prior to portions of the initial layer of fibres being superimposed upon each other to form an assembled semi-finished mineral wool batt. In this way, as illustrated in FIG. 6, superabsorbent particles 12 are positioned at or in the vicinity of the core 11 of the semi-finished mineral wool batt 21 before needling (due to prior super positioning of the layers from which the semi-finished mineral wool batt is assembled) and the needling then serves: [0055] If required, to push any superabsorbent particles 12 which are distributed at a surface of the semi-finished mineral wool batt 21 in to the absorbent later or core 11 of the mineral wool batt; and/or [0056] To more evenly distribute superabsorbent particles 12 which are already positioned at or in the vicinity of the absorbent layer or core 11; and/or [0057] To needle the fibres between each other (which increases the stability of the mineral wool batt); and/or [0058] To increase the density of the absorbent later or core 11 of the mineral wool batt 21, preferably to a density in the range 30 to 120 kg/m.sup.3 or in the range 30 to 160 kg/m.sup.3; and/or [0059] To cause the super absorbent particles 12 to be trapped between fibres at the absorbent layer or core 11 of the mineral wool batt; and/or [0060] To create an upper barrier layer 13 and a lower barrier layer 14, each of which is has a higher density than the core 11 of the batt and each of which provides increased resistance to escape of superabsorbent particles 12 from the batt 21.

[0061] Such an approach may be used when the semi-finished mineral wool batt 21 is assembled by superimposing two or more initial layers of fibres, for example by pendulum folding.

[0062] FIG. 7 is similar to FIG. 6 and illustrates: (i) on its left hand side the substantially horizontal orientation of fibres and the arrangement of superabsorbent particles in layer(s) prior to needling and (ii) on its right hand side, the effect of needling creating a more even distribution of superabsorbent particles throughout the thickness of the mineral wool batt, or at least the core of the mineral wool batt, and an orientation of fibres of the needled mineral wool batt with a significant proportion of the fibres having a vertical or non-horizontal component of direction and the mass of fibres forming interstices in which at least some of the super absorbent particles are trapped.

EXAMPLES

[0063] The following samples were tested:

TABLE-US-00001 Examples batts of needled, stone wool fibres with no binder cut in to a 1.1 and 1.2 circle with a radius of 19.5 cm. Density: 110 kg/cm.sup.3; thickness: 20 mm; quantity of superabsorbent particles; 60 g/m.sup.2 Examples batts of needled, stone wool fibres with no binder cut in to a 2.1 and 2.2 circle with a radius of 19.5 cm. Density: 110 kg/cm.sup.3; thickness: 20 mm; no superabsorbent particles Example 3 batts of needled, stone wool fibres with no binder cut in to a 17 cm square. Density: 110 kg/cm.sup.3; thickness: 20 mm; quantity of superabsorbent particles: 15 g/m.sup.2 Example 4 batts of needled, stone wool fibres with no binder cut in to a 17 cm square. Density: 110 kg/cm.sup.3; thickness: 20 mm; no superabsorbent particles Examples As examples 1.1 and 1.2 but cut to size to fit test apparatus 5.1 and 5.2 Examples As example 3 but cut to size to fit test apparatus 6.1 and 6.2 Examples As examples 2.1, 2.2 and 4 but cut to size to fit test apparatus 7.1 and 7.2

[0064] Initial Water Retention and Initial Water Content (Cycle 1C1)

[0065] Three samples of each example were tested; the results presented below are the mean average of the three samples.

[0066] At the beginning of each test for initial water retention, each sample is weighed, its dry weight recorded, and then soaked in tap water for about 2 hours; the samples are then placed on a metal grid at normal room conditions (temperature about 20 C.5 C.; pressure about 101 kPa20%; relative humidity about 40% to 80%, preferably about 60%10%) in the laboratory for conditioning. The samples are weighted after 5 minutes 1 day, 2 days, 3 days and 4 days.

Table 1 shows the water retention which is calculated as

(mass of wet samplemass of dry sample)/mass of dry sample

and expressed as kg water per kg (dry weight) of mineral wool batt. The t0 initial water retention is defined as the water retention after five minutes (i.e. once the excess water from the sample being soaked is allowed to drain off).

TABLE-US-00002 TABLE 1 water retention (kg/kg) 5 min Example (t0) 1 day 2 day 3 day 4 day 1.1 10.4 4.6 2.7 1.2 10.4 8.1 5.9 3.5 1.4 2.1 7.3 2.1 0.1 2.2 8.7 6.5 4.3 2.0 0.1
Table 2 shows the water content which is calculated as

(mass of wet samplemass of dry sample)/mass of wet sample

and expressed as a percentage. The initial water content is defined as the water content after five minutes (i.e. once the excess water from the sample being soaked is allowed to drain off).

TABLE-US-00003 TABLE 2 water content (%) 5 min Example (t0) 1 day 2 day 3 day 4 day 1.1 91 82 73 1.2 91 89 85 78 56 2.1 88 68 11 2.2 90 87 81 67 7

[0067] Cycled Water Retention and Cycled Water Content (Cycles 1 to 5C1 to C5)

[0068] Cycled water retention and cycled water content of Examples 3 and 4 was evaluated in a similar way as above and defined as:

TABLE-US-00004 Cycle 1 C1 Determined in the same way as initial water retention and initial water content Cycle 2 C2 Determined in respect of samples which, after cycle 1 are dried, soaked again in tap water for at least 2 hours and re-measured Cycle 3 C3 Determined in respect of samples which, after cycle 2 are dried, soaked again in tap water for at least 2 hours and re-measured Cycle 4 C4 Determined in respect of samples which, after cycle 3 are dried, soaked again in tap water for at least 2 hours and re-measured Cycle 5 C5 Determined in respect of samples which, after cycle 4 are dried, soaked again in tap water for at least 2 hours and re-measured

[0069] and in which the drying out of the samples between each cycle is carried out by allowing the samples to dry in the normal room conditions until their water retention is less than 0.1, preferably substantially 0. The results are shown in Tables 3, 4, 5 and 6. Three samples of each example were tested; the results presented below are the mean average of the three samples.

TABLE-US-00005 TABLE 3 Example 3 - water retention (kg/kg) following each cycle 5 min Cycle (t0) 1 day 2 day 3 day 4 day C1 9.8 7.4 5.2 3.1 1.1 C2 8.9 6.9 5.1 3.6 1.8 C3 8.4 6.8 5.1 3.2 1.9 C4 8.3 6.0 4.3 2.2 0.8 C5 8.1 6.2 4.7 3.4 2.4

TABLE-US-00006 TABLE 4 Example 3 - water content (%) following each cycle 5 min Cycle (t0) 1 day 2 day 3 day 4 day C1 90 87 84 78 65 C2 89 87 84 76 65 C3 89 86 81 69 44 C4 89 86 82 77 71 C5 89 86 82 75 58

TABLE-US-00007 TABLE 5 Example 4 - water retention (kg/kg) following each cycle 5 min Cycle (t0) 1 day 2 day 3 day 4 day C1 8.6 6.5 4.7 2.7 0.9 C2 8.0 6.0 4.1 2.5 1.1 C3 7.8 6.1 4.4 2.5 1.1 C4 7.4 5.3 3.4 1.3 0.2 C5 7.4 5.7 4.0 2.7 1.6

TABLE-US-00008 TABLE 6 Example 4 - water content (%) following each cycle 5 min Cycle (t0) 1 day 2 day 3 day 4 day C1 90 87 82 72 39 C2 89 86 80 72 52 C3 89 86 81 71 52 C4 88 84 77 53 13 C5 88 85 80 73 61

[0070] VSE Water Content (Vacuum Simulated Evaporation)

[0071] A vacuum simulated evaporation (VSE) test is performed using a sand suction table according to European standard EN 13041 of December 1999. The sample is cut to the internal dimensions of a rigid test ring (internal diameter 100 mm, height 50 mm, open at both ends and of known mass), weighed (dry weight), placed in the test ring and soaked in water until saturation. The test ring is then placed on the sand suction table and left for 24 hours to reach equilibrium conditions before being weighed so as to determine the water content of the sample. The test ring is then returned to the sand suction table, a vacuum of 3.2 cm water is applied through the base of the sand suction table and the sample is left in these conditions for 24 hours to reach equilibrium before being weighed again to determine the water content of the sample. The test ring is then returned to the sand suction table, a vacuum of 10 cm water is applied through the base of the sand suction table and the sample is left in these conditions for 24 hours to reach equilibrium before being weighed again to determine the water content of the sample. The procedure is repeated systematically so as the determine the water content of the sample after equilibrium after sequential application of a vacuum of 3.2 cm water, 10 cm water, 32 cm water, 50 cm water and 100 cm water, the results being shown in Table 7:

TABLE-US-00009 TABLE 7 VSE water content (%) After vacuum of: 3.2 cm 10 cm 32 cm 50 cm 100 cm Example 5.1 96 91 56 50 48 Example 6.1 96 90 46 38 37 Example 7.1 96 94 20 9 6

[0072] WOK Water Absorption

[0073] The WOK method (WOK=water uptake characteristic) as developed by Stichting RHP, Galgeweg 38, 2691 MG's-Gravenzande, The Netherlands www.rhp.nl is used to determine water re-absorption of examples 5.2, 6.2 and 7.2. The sample to be tested is placed in a ring, soaked in water until saturation, left to reach equilibrium on a sand suction table, weighed to determine its initial water content, dried to equilibrium on a sand suction table at a vacuum of 100 cm water and then further dried in an oven at 40 C. for 72 hours before being weighed (dry weight). The sample is arranged such that the mineral fibres are just in contact with water and its water content is determined as a function of time and expressed as a % of initial water content. Results are shown in Table 8:

TABLE-US-00010 TABLE 8 WOK water content (%) Time (minutes) 15 30 60 90 120 240 Example 5.2 52 64 74 78 80 85 Example 6.2 83 89 92 93 94 95 Example 7.2 72 72 72 72 72 72

[0074] Preferred individual characteristics and combinations of characteristics of products in accordance with the invention are set out in the following tables:

TABLE-US-00011 Preferred characteristics for initial water retention (kg/kg): More Most Characteristic Preferred preferred preferred t0 initial water retention 6.5 7 8.5 initial water retention after day 1 5.5 6.5 7 initial water retention after day 2 4.0 4.5 5 initial water retention after day 3 2 3 4 initial water retention after day 4 0.8 1.0 2

TABLE-US-00012 Preferred characteristics for initial water content (%): More Most Characteristic Preferred preferred preferred t0 initial water content 70 80 85 initial water content after day 1 65 75 82 initial water content after day 2 60 70 80 initial water content after day 3 50 65 70 initial water content after day 4 5 50 55

TABLE-US-00013 Preferred characteristics for cycled water retention after cycle 4 (kg/kg) More Most Characteristic Preferred preferred preferred t0 cycled water retention 6.5 7.0 7.5 cycled water retention after day 1 4.5 5.0 5.5 cycled water retention after day 2 2.5 3.0 4.0 cycled water retention after day 3 0.8 1.0 1.5 cycled water retention after day 4 0.1 0.2 0.5

TABLE-US-00014 Preferred characteristics for cycled water content after cycle 4 (%) More Most Characteristic Preferred preferred preferred t0 cycled water content 75 80 85 cycled water content after day 1 72 77 82 cycled water content after day 2 70 75 80 cycled water content after day 3 50 60 70 cycled water content after day 4 10 50 65

TABLE-US-00015 Preferred characteristics for VSE water content (%) More Most Characteristic Preferred preferred preferred VSE water content after vacuum of 85 90 92 3.2 cm VSE water content after vacuum of 70 80 85 10 cm VSE water content after vacuum of 35 40 50 32 cm VSE water content after vacuum of 20 30 40 50 cm VSE water content after vacuum of 15 30 40 100 cm

TABLE-US-00016 Preferred characteristics for WOK water content (%) More Most Characteristic Preferred preferred preferred WOK water content after 15 minutes 50 65 75 WOK water content after 30 minutes 65 75 80