Method for manufacturing an aerogel-containing composite and composite produced by that method

Abstract

Method for manufacturing an aerogel-containing composite, said method comprising the steps of: providing fibers, at least some of which are first fibers, such as mineral fibers, polymer fibers, cellulose fibers, or other types of fibers, in an amount of from 3 to 80 wt % of the total weight of starting materials, providing an aerogel particulate material in an amount of from 10 to 75 wt % of the total weight of starting materials, providing a binder in an amount of from 1 to 30 wt % of the total weight of starting materials, suspending the fibers in a primary air flow and suspending the aerogel particulate material in the primary air flow, thereby mixing the suspended aerogel particulate material with the suspended fibers, mixing the binder with the fibers and/or aerogel particulate material before, during or after mixing of the fibers with the aerogel particulate material, collecting the mixture of fibers, aerogel particulate material and binder and pressing and curing the mixture to provide a consolidated composite with a density of from 120 kg/m.sup.3 to 800 kg/m.sup.3. With this method homogeneous composites can be produced.

Claims

1. A method for manufacturing an aerogel-containing composite from starting materials having a total weight, said method comprising: providing fibres, at least some of which are first fibres of a first material in an amount of from 3 to 80 wt % of the total weight of starting materials, providing an aerogel particulate material in an amount of from 10 to 75 wt % of the total weight of starting materials, providing a binder in an amount of from 1 to 30 wt % of the total weight of starting materials, suspending the fibres in a primary air flow and suspending the aerogel particulate material in the primary air flow, thereby mixing the suspended aerogel particulate material with the suspended fibres, wherein the aerogel particulate material is provided to the primary airflow via a tributary airflow, and wherein the primary airflow is lateral and the tributary airflow is upwards, mixing the binder with the fibres and/or aerogel particulate material before, during or after mixing of the fibres with the aerogel particulate material, thereby forming a mixture, collecting the mixture and pressing and curing the mixture to provide a consolidated composite with a density of from 120 kg/m.sup.3 to 800 kg/m.sup.3.

2. A method according to claim 1, comprising an intermediate step of providing second fibres of a second material different from the first material of the first fibres in an amount of 3 to 80 wt % of the total weight of starting materials.

3. A method according to claim 1, wherein the first fibres are mineral fibres.

4. A method according to claim 2, wherein the second fibres are polymer fibres.

5. A method according to claim 1, wherein the step of mixing binder with the fibres is performed before suspending the fibres in the primary air flow.

6. A method according to claim 1, wherein the first fibres are stone wool fibres.

7. A method according to claim 1, wherein the step of mixing binder with the fibres is performed at production of the fibres.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be described in the following by way of example and with reference to the drawings in which

(2) FIG. 1 is a schematic drawing of an apparatus for fibre separating and mixing raw materials.

(3) FIG. 2 is a schematic drawing of a further disentanglement apparatus as described above.

(4) FIG. 3 is a photo of a composite panel according to the invention made in a pilot run.

(5) FIG. 4 is a microscope photo of a sample of an aerogel-containing composite according to the invention.

(6) FIG. 5 is a microscope photo of a sample of an aerogel-containing composite according to the invention.

(7) FIG. 6 is a microscope photo of a sample of an aerogel-containing composite according to the invention.

(8) FIG. 7 is a photograph of a composite manufactured using a mixing method other than that according to the invention.

(9) FIG. 8 is a photograph of further composites manufactured using a mixing method other than that according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(10) Apparatus suitable for use in the method of the present invention can be seen in FIG. 1. Where a fibre-forming apparatus and collector are configured to carry a mineral fibre web to the inlet duct 1, a binder supply means is positioned to supply binder to the mineral fibres and an aerogel particulate supply means is positioned to supply aerogel particulate material to the inlet duct, the apparatus shown could also form part of the first novel apparatus of the invention.

(11) Supply means to supply second fibres (not shown) can also be provided to supply second fibres to the inlet duct 1.

(12) The apparatus comprises an inlet duct 1 for starting materials, e.g. aerogel particles, binder and mineral fibres and for specific raw materials the apparatus may comprise a shredder (not shown) at the inlet duct 1 to at least partly cut up bulky material. At the lower edge of the inlet duct, there is a conveyor 2 that carries the raw materials through the inlet duct 1. At the upper edge of the inlet duct, conveying rollers 3 assist with feeding the starting materials through the inlet duct 1. At the end of the inlet duct 1, a first set of mutually spaced elongate elements 4 extend across the end of the inlet duct 1. These serve to break up larger pieces of the starting materials, for example the mineral fibre web. In some embodiments, the elongate elements 4 are in the form of rotating brushes that draw the starting materials between them as they rotate.

(13) The starting materials that pass through the end of the inlet then fall downwards into a substantially vertical duct 5. In the embodiment shown, a second set of mutually spaced elongate elements 6 extend across the upper end of the duct. The second set of elongate element is usually more closely spaced than the first. In the embodiment shown, the second set of elongate elements rotate so as to allow sufficiently small pieces of the mineral fibre web to pass through, but carry larger pieces away via a starting material recycling duct 7.

(14) The vertical duct 5 generally becomes narrower at its lower end. In the embodiment shown, the lower end of the vertical duct forms the inlet 8 to the substantially cylindrical chamber 9. As shown, the inlet 8 is at an upper part of the substantially cylindrical chamber 9. In use, starting materials pass through the vertical duct 5 and through the inlet 8 into the cylindrical chamber 9.

(15) The cylindrical chamber 9 houses a roller 10 having spikes 11 protruding from its circumferential surface 12. The roller 10 shown in FIG. 1 rotates anticlockwise as shown in the drawing, so that starting materials are carried from the inlet 8 around the left side of the roller 10 as shown and thrown out laterally in a primary air flow into a mixing chamber 14. The cylindrical chamber 9 and the roller 10 together form the disentanglement means. The disentanglement means cause disentanglement of the fibres, meaning that the fibres, which may be provided as wool entangled as a web or as tufts, will be worked on to provide more open wool or even loose fibres, thereby facilitating subsequent mixing of the fibres with other components.

(16) In the embodiment shown, the primary air flow is created by the rotation of the roller 10 within the cylindrical chamber 9, and in particular by the movement of the spikes 11 and starting material through the space between the circumferential surface of the roller and the curved wall 13 of the cylindrical chamber 9. The pattern of spikes 11 on the roller 10 may have some effect on the mixing process.

(17) The mixing process is very complex and difficult to investigate. With the embodiment shown it is believed that most of the mixing takes place by the influence of the roller 10 and the spikes 11, whereas only a relatively small additional mixing takes place in the mixing chamber 14. It is believed there is some physical shearing and mixing of aerogel particulates and fibres effected by the spikes of the roller, but that the main effect of the spikes is the sudden increase in speed and turbulence of the air flow.

(18) The mixing chamber 14 shown in FIG. 1 comprises a discharge opening 16 and further air flow supply means 15. The further air flow supply means 15 comprise openings through which the further air flow is supplied. Gauzes 17 are disposed across the openings of the further air flow supply means 15. These gauzes allow the further air flow to pass through into the mixing chamber 14, but are intended to prevent the entry of materials into the supply means. The further air flow supply means 15 direct the further air flow upwards into the mixing chamber 14.

(19) The further air flow meets the primary air flow containing the disentangled fibres in the mixing chamber. The further air flow has the effect of carrying the mixture of disentangled fibres, binder and aerogel particulate material upwards within the mixing chamber 14. Some more compacted fibres and pearls of mineral material will not be carried upwards in the mixing chamber, but fall to the lower end and through the discharge opening 16.

(20) The desired mixture of disentangled fibres, aerogel particulate material and binder is carried to the upper part of the mixing chamber 14 where a removal duct 18 is positioned to carry the mixture from the mixing chamber 14. A first air recycling duct 19 is adjoined to the removal duct 18 and recycles some of the air from the removal duct 18 back to the further air supply means 15.

(21) The removal duct leads to a cyclone chamber 20. The cyclone chamber 20 has a second air recycling duct 22 leading from its upper end to the further air supply means 15. A filter 21 is adjoined to the second air recycling duct. In use, the filter 21 removes any stray mineral fibres, aerogel particulate material and binder from the second air recycling duct 22. As air is removed from the upper end of the cyclone chamber 20, the mixture of disentangled fibres, aerogel particulate material and binder falls through a cyclone chamber outlet 23 at the lower end of the cyclone chamber 20.

(22) A collector 24 is positioned below the cyclone chamber outlet 23. In the embodiment shown, the collector 24 is in the form of a conveyor, which carries the collected fibres to a pressing and curing apparatus (not shown).

(23) FIG. 2 shows an embodiment of the further disentanglement apparatus, which may optionally be used in the method. The further disentanglement apparatus can be positioned in place of collector 24 as shown in FIG. 1 or after the collector 24. Having both the collector 24 and the further disentanglement apparatus is found to produce the best results in terms of homogeneous products. The further disentanglement apparatus shown comprises roller 25, which is the same as roller 10 in structure. Again the pattern of spikes on the roller may influence the mixing process and hence the variation in distribution of the various ingredients of the mixture. The mixture of components is fed to roller 25 from above and thrown out into forming chamber 26. At its lower end, the forming chamber 26 comprises a foraminous conveyor belt 27, below which suction means 28 are positioned. Scalper 29 is positioned to scalp the top of the mixture to provide an even surface. The scalped material can then be recycled.

(24) Foraminous conveyor belt 27 carries the mixture to a press (not shown).

(25) The photo in FIG. 3 depicts a composite panel produced in a pilot run on a full-scale apparatus according to the invention. The composite raw materials fed into the apparatus were uncured stone wool web with wet binder and aerogel particulates. The sample shown is approximately 20 cm20 cm. The composite panel is seen to be very homogeneous. It is not possible to see the aerogel particles with the naked eye. The stone wool web was disintegrated and opened up in the apparatus, and there are only small fibre tufts visible on the surface, and there is a random pattern of the small fibre tufts, so there is no indication of accumulation or variation in distribution.

(26) The microscope photo of FIG. 4 shows a sample of an aerogel-containing composite made according to the invention using loose stone wool fibres. The aerogel particulate material can be seen as small dots or grains. The fibres are also visible. As can be seen the aerogel particulate material and fibres are substantially homogeneously mixed on a 1 mm scale.

(27) The microscope photograph of FIG. 5 shows the mixture of aerogel particles and fibres in the panel according to the invention. The two largest particles are measured to 481 m and 302 m. The composition of the analysed panel was approximately 51 wt % aerogel particles, 38 wt % mineral wool fibres and 11 wt % binder.

(28) Similarly the microscope photograph of FIG. 6 shows the mixture of aerogel particles and fibres in the panel according to the invention in larger magnification. There is no sign that the binder attaches to the aerogel particles. This is considered highly beneficial as mentioned above.

(29) A series of tests were carried out with different amount of the various ingredients, different types of binder etc. as can be seen in table 1 below. Panels were produced with dry powder binder, different types of aerogel, different types of fibres and different percentages of the ingredients. The table also show that it is possible to produce composites in a broad range of densities and ingredients showing the versatility of the method and apparatus according to the invention. As mentioned above it is believed that this versatility is mainly due to the homogeneous mixing with the apparatus and method.

(30) TABLE-US-00001 Patent Sample Binder aerogel Fibre type Density % % % % 2nd no. no. type type Fibre type 2 kg/m.sup.3 Lambda aerogel MIWO binder fibre 1 W 1.13 Powder none Rockpanel Aramide 600 x 0.0 84.8 1.7 4.5 2 2.23 Powder TLD 101 Rockpanel 479 37.1 26.8 62.5 10.7 0.0 3 2.40 Powder TLD 301 Rockpanel 193 17.6 52.2 34.8 13.0 0.0 4 3.3 Powder TLD 101 Rockpanel 300 19.1 51.7 34.5 13.8 0.0 5 5.5 liquid TLD101 Line 2 530 41.4 28.9 67.4 3.7 0.0 6 5.9 Powder TLD101 Rockpanel 600 33.1 26.8 62.5 10.7 0.0 7 6.1 liquid TLD101 Line 2 200 18 55.0 36.7 8.3 0.0 8 6.7 liquid TLD101 Line 2 600 36.6 27.5 64.2 8.3 0.0 9 7.17 Powder TLD102 Rockpanel E-glass 200 20 52.2 17.4 13.0 17.4

(31) As reflected by the tests listed in the table above composites of a wide range of compositions and densities were produced and with a lambda as low as 20.

(32) The powder binder in the test is a dry phenol formaldehyde polymer binder of the type sold by Dynea under the trade name Prefere 94 8182U7.

(33) The liquid binder in the test is a phenol formaldehyde binder.

(34) Fibre type Rockpanel is loose stone wool fibres, whereas fibre type Line 2 is an uncured web of stone wool fibres impregnated with a liquid binder.

(35) Curing lasted approximately 15 minutes.

(36) In tests, aerogel particulate material of the type Nanogel Aerogel from Cabot International was used and showed excellent results.

(37) The tests were carried out with stone wool fibres having a density of approximately 2,800 kg/m.sup.3.

(38) In some tests fibres were provided in the form of a collected web and the collected web of fibres subjected to a disentanglement process. In other tests fibres were provided in the form of loose fibres.

(39) The requirement for the composite of being substantially homogeneous is, in this case, considered fulfilled with a maximum variation of 5% in an X-Y plane co-planar with the major surfaces of the composite panel. A higher variation is accepted in the Z-plane, i.e. the thickness of the composite panel.

(40) FIGS. 7 and 8 are comparative examples showing composites not produced according to the invention.

(41) FIG. 7 is a photograph showing the result achieved when the components of the composite are mixed by a method not according to the present invention. In this case, the components were mixed with a blender mixer. It is clear from FIG. 7 that the composite is not homogeneous, because compacted balls of fibres and separated regions of aerogel, fibres and binder are visible with the naked eye. This is in contrast to the smooth and homogeneous appearance of composites manufactured according to the invention, in particular as shown in FIG. 3.

(42) Similarly, FIG. 8 is a photograph of a number of composites comprising 10-31% aerogel particulate material, mineral fibres and approximately 10% dry binder. The components of the composite were mixed in a blender using a method not according to the invention. Again, compacted balls of fibres and distinct regions of the different components can be seen in the composites, which is in contrast to the homogeneous appearance of composites manufactured according to the invention, in particular as shown in FIG. 3.