WO2009089579A2

WO2009089579A2 - Forming non woven mats

Info

Publication number: WO2009089579A2
Application number: PCT/AU2009/000034
Authority: WO
Inventors: Hugh William Eric Higgins
Original assignee: Boral Australian Gypsum Limited
Priority date: 2008-01-15
Filing date: 2009-01-15
Publication date: 2009-07-23
Also published as: NZ587184A; WO2009089579A3; AU2009204678A1

Abstract

Processes for manufacturing non woven mats containing inorganic fibres, and having relatively high loft and thermal rating. The process involve two fibre opening stages, typically a first coarse opening stage followed by a second finer stage, preferably involving a squeeze roller, nosebar and lickerin. The second stage may result in a layered mat. Inorganic fibres may be blended with polymer melt fibres before the first opening stage, or with a binder at a suitable point after the opening stages. The mats may be used for thermal insulation products.

Description

FORMING NON WOVEN MATS

FIELD OF THE INVENTION

This invention relates to methods and apparatus for forming thermal insulation from glass fibres, particularly methods which may be used to manufacture products having a high loft and thermal rating.

BACKGROUND TO THE INVENTION

Glass fibre insulation is an important building material for thermal and acoustic insulation of dwellings as well as commercial and industrial buildings. With increasing awareness of the environment and the need to reduce green house gas emissions, building insulation is becoming and evermore important material in helping reduce the heating and cooling energy loads placed upon electricity generators.

Conventional means of manufacturing glass wool insulation usually involve melting glass in a furnace, drawing fine glass strands through bushings and spinnerets, allowing the fibre strands to fall on a conveyor which is treated by spraying with a solution of phenol formaldehyde resin and curing the resinous mat in an oven at temperatures of approximately 230°C. The product is discharged to a slitting station where it is either packaged into rolls or cut and stacked as batts and compress packaged.

It has not previously been suggested that a suitable building insulation could be manufactured by using chop strand glass fibre, binder fibre and non-woven machinery such as a card and cross lapper or an airlay coupled with a curing oven and the required ancillary equipment. Conventional airlay equipment would not normally be expected to produce a mat with sufficiently high loft and thermal rating.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide for improved formation of fibreglass insulation, or at least to provide an alternative to existing methods. In one aspect the invention resides in a method of forming a non-woven mat of fibres, including: forming a bed of fibres containing inorganic fibres blended from one or more fibre sources, feeding the bed into a first opener to form a mat having coarsely opened fibres, feeding the coarsely opened mat into a second opener to form a mat having finely opened fibres, and curing the finely opened mat; wherein the second opener includes a squeeze roller, nose bar, and a lickerin.

Preferably the first opener includes a squeeze roller, a nose bar, and a lickerin. Alternatively the first opener includes two opposed squeeze rollers and a lickerin.

Preferably the coarsely opened mat primarily contains randomised fibres without a regular visible structure. The finely opened mat primarily contains individualised fibres with a partly or wholly layered structure.

hi a further aspect the invention resides in a method of forming a non- woven mat of fibres, including: forming a bed of fibres containing inorganic fibres blended from one or more fibre sources, feeding the bed into a first opener to form a mat of largely opened fibres, feeding the opened mat into a second opener to form a mat having multiple fibre layers, and curing the multiple layered mat.

Preferably the first and/or second opener includes a respective squeeze roller, nose bar, and lickerin. Preferably both first and second openers include a squeeze roller having a rubberised surface and a carding surface respectively.

In another aspect the invention resides in apparatus for forming a non woven mat, including: a blender which forms a bed from one ore more fibre sources, a first fibre opener which forms a coarsely opened mat from the bed, a second fibre opener which forms a finely opened mat from the coarsely opened mat, and an oven which cures the finely opened mat; wherein the second fibre opener includes a squeeze roller, nose bar, and a lickerin.

Preferably the first fibre opener includes a squeeze roller, nose bar, and a lickerin. Alternatively the first fibre opener includes two opposed squeeze rollers and a lickerin. Preferably the squeeze roller of the first opener has a rubberised surface and the squeeze roller of the second opener has a carding surface. Preferably an anti static device is included between the first and second fibre openers. The anti static device is typically a water sprayer.

In a still further aspect the invention resides in a method of manufacturing a non woven insulation product, including: combining glass fibres with polymer melt fibres, opening the combined fibres in a two stage opening process, forming the combined glass fibres into a high loft matt, bonding the fibres in the matt by heating to melt the melt fibres, and forming the bonded matt into a product of required dimensions.

In an alternative aspect the invention resides in a method of manufacturing a non woven insulation product, including: opening glass fibres in a two stage opening process, forming the opened glass fibres into a high loft mat, adding a resin powder to the mat, bonding the fibres in the mat by heating to melt the resin, and forming the bonded mat into a product of required dimensions.

Preferably the first opening stage includes a rotating drum with relatively coarse carding wire and the second opening stage includes a rotating drum with relatively fine carding wire.

Preferably the glass fibres are Eglass with an average diameter in the range 9 to 14 microns. Preferably the glass fibres are blended at 50 to 90% by weight with the polymer melt fibres.

Preferably the insulation product has a thermal rating R between 1.5 and 6. Preferably the product has a loft between 90 and 220 mm, and a weight between 900 g/m² and 3 kg/m².

The invention also resides in any alternative combination of features that are indicated in this specification. All known equivalents are deemed to be included whether or not explicitly set out.

LIST OF FIGURES

Preferred embodiments of the invention will be described with respect to the drawings, of which: Figure 1 schematically shows a two stage airlay process which forms a non woven mat,

Figure 2 provides detail of a first fibre opener in the airlay process,

Figure 3 provides detail of a second fibre opener in the airlay process, Figure 4 shows an alternative fibre opener,

Figure 5 gives thermal performance data relating to fibreglass batts,

Figure 6 schematically shows alternative fibre openers,

Figure 7 shows a two stage process which combines glass fibres and polymer melt fibres, Figure 8 shows a process in which resin powder is added to a mat formed from glass fibres,

Figure 9 shows a first opener for either process in Figure 7 or Figure 8, and

Figure 10 shows a second opener for either process.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the drawings it will be appreciated that the invention can be implemented in a wide range of ways using a two stage opening process and inorganic fibres. It will also be appreciated that manufacture of non woven mats using the airlay process and a range of commercially available equipment is well known, and that conventional aspects of the equipment and process need not be described in detail. Alternative manufacturing processes involving carding and cross-lapping will also be known. These embodiments have been given by way of example only.

Figure 1 shows the main components of an airlay process in which fibres are blended, opened and formed into a mat, which can then be cured and cut into a product such as insulation batts for example. The fibres are generally obtained from two or more sources (not shown), and preferably include an inorganic fibre such as fibreglass, and a melt fibre such as a bicomponent polymer. Other fibres or substances may also be added depending on the required product.

The fibre sources for Figure 1 include stock materials which are separated and roughly blended in a condenser 10 which forms a bed 11 on a conveyor. The bed generally contains clumps of fibres which must be opened and mixed. A first fibre opener 12 carries out a coarse opening stage and is followed by a second fibre opener 13 which carries out a fine opening stage. The bed 11 is thereby converted into a mat 14. Static electricity created by the inorganic fibres must usually be reduced after the first opening stage, and an antistatic system such as a water sprayer 15 may be required between the two stages. The mat is cured in a suitable fashion, typically in an oven 16 which binds the inorganic fibres and the melt fibres.

Figure 2 provides more detail of a preferred first opening stage in Figure 1. The fibre opener includes a squeeze roller 20, nose bar 21 and lickerin drum 22. The nose bar is a feed plate which is shaped for close operation with the feed roller and the lickerin drum, and has a work point or edge 23 which is located between these components. The lickerin is a carding roller which combs and separates the fibres from the incorning bed of material and pulls the fibres over the edge of the nose bar. An air current 24 then carries the fibres downwards towards an outgoing conveyor 25. A vacuum may be applied beneath the conveyor to assist the airflow.

The first opening stage shown in Figure 2 results in largely randomised fibres, possibly still with some partial alignments, that are placed on the conveyor to form a relatively low loft web.

In example apparatus the squeeze roller in Figure 2 is a rubber coated cylinder about 200mm in diameter, set about 5mm from the edge of the nose bar. The rotational speed of the roller is set such that its tip speed is equal the speed of the incoming conveyor, and these are controlled together to a speed of about 1-2Om per minute. The lickerin drum is cylinder about 600mm in diameter also set about 5mm from the nose bar, and wound with saw tooth carding wire of about 10-12 gauge. The lickerin rotates at about 800-lOOOrρm and is located about 600mm above the outgoing conveyor.

Figure 3 provides more detail of a preferred second opening stage in Figure 1. The fibre opener includes a squeeze roller 30, nose bar 31 and lickerin drum 32. These components are similar to the first opener in Figure 2 but are operated differently. The nose bar 31 is a feed plate shaped for close operation with the feed roller and the lickerin drum. The nose bar has a work point or edge 33 which is located between these components. The lickerin is a carding roller which combs and separates the fibres from the incoming bed of material and pulls the fibres over the edge of the nose bar. An air current 34 then carries the fibres downwards towards an outgoing conveyor 35 through which a vacuum may be applied. The second opening stage shown in Figure 3 results in a mat 14 having layers of primarily finely opened and individualised fibres. The mat may be partly or wholly layered and forms a relatively high loft web.

In example apparatus the squeeze roller in Figure 3 is about 200mm in diameter and wound with carding wire of about 16 gauge. The roller is set about 2mm or less from the edge of the nose bar and has a speed matching the incoming conveyor. The lickerin drum is a cylinder about 600mm in diameter also set about 2mm or less from the nosebar and wound with 16 gauge carding wire. The lickerin rotates at about 1800-2000rpm and is located at about 800mm about the outgoing conveyor.

Figure 4 shows an alternative opening stage having a squeeze roller 4O₅ nose bar 41, lickerin drum 42, guide roller 43 and a moving plate 46. The moving plate is an optional feature which assists the layering process. The nosebar functions generally as described above and an airflow 44 carries fibres onto a conveyor 45. The system shown here may be used as the second opening stage to create a mat 14.

In the example of Figure 4 the plate extends across the width of the mat and the rollers and oscillates as indicated at about 35 to 60 cycles per minute. The plate is typically up to about 200mm wide and pivots about a fixed edge which is located upstream in the flow of fibres. The plate has a free edge located downstream in the flow of fibres, which moves up to about 200mm during each cycle. In a prototype the lickerin has been rotated at speeds of about 3000rpm.

Figure 5 contains three tables which enable a rough comparison between the properties of fibreglass insulation formed using a conventional airlay process and insulation formed using a modified process such as described in relation to figures 1-3. Conventional airlay processes generally use opening stages which involve squeeze rollers rather than a nosebar, as shown in Figure 6 for example, and also use relatively fine fibres. The inorganic fibres used in the modified process were StarStran LCF 991, 51 mm chopped strand supplied by Johns Manville specifically for carding and airlaying, and had a mean diameter of about 13μm. The binder fibres were bi-component fibre from the Far Eastern Textile Company: 4 denier 51 mm core-sheath low melt. It can be seen that a mat formed by the modified process had an R rating comparable to a mat formed by the conventional phenolic formaldehyde resin glass wool process.

Mats formed according to the process of Figures 1-3 typically have a loft in the range 90 to 220mm, a weight in the range 850 to 2200 gsm, and a thermal resistance in the range 1.5 to 6,0 m²K/W. However, a range of characteristics are possible.

Figure 6 shows a range of opening stages which are typically used in conventional airlay equipment. These involve various combinations of squeeze rollers and lickerin drums which need not be described in detail. None involve a nosebar. The opening stages shown in Figure 6a., 6b, 6c and 6d respectively involve a single squeeze roller, a double squeeze roller, a pair of double squeeze rollers, and a double squeeze roller plus a transfer roller. A conventional opener such as shown in Figure 6 might be used in the first opening stage shown in Figure 1, rather than a nosebar system such as shown in Figure 2, although the results are expected to be inferior to the examples given above. The second opening stage preferably always involves a nose bar and associated rollers as shown in Figures 3 or 4.

Figures 7 and 8 show the main components of an overall manufacturing process for inorganic insulation products such as fibreglass batts. Each includes two initial fibre opening stages followed by a mat forming process such as described above. The initial opening stages have been required in some cases to ensure that clumps of fibres are thoroughly worked and opened prior to the relatively fine stages described above. The inorganic fibres which are used in these processes are bonded in two different ways to form a suitably robust structure. The fibres are preferably Eglass and other fibres or substances may be added depending on the required product.

In Figure 7, glass fibres from bins 70 are initially combined with polymer melt fibres from bin 71, typically bi-component polymer fibres which partially melt when the mat is cured. The mixture then passes through two coarse opening stages 72 and 73, before a bed of fibres is passed into a mat forming process 74 such as described above. The resulting mat is then cured in an oven 75.

In Figure 8, glass fibres from bins 80 are blended alone, with a resin powder being added by an applicator 81, before the mat enters the oven 85. The initial blend passes through two coarse opening stages 82, 83, before a bed of fibres is passed into a mat forming process such as described in relation to Figure 1. An airlay process or carding and crosslapping process may be used for example. These components are typically the same as the components in Figure 7 but may be varied depending on the product.

The fibre sources in Figures 7 and 8 include stock materials which are provided in a series of bins from which they are roughly separated and formed into a bed on a conveyor. The bed generally contains clumps of fibres which must be opened and mixed, A first fibre opener carries out a coarse opening stage and is followed by a second fibre opener which carries out a relatively fine opening stage and forms the mat. Static electricity created by the inorganic fibres must usually be reduced after either or both opening stages, and antistatic systems such as water mist sprayers may be required.

Figure 9 provides more detail of the first opening stage 72 or 82 in Figure 7 or 8. The opener includes an upright housing 90 containing a passage which feeds fibres to a combination of squeeze rollers 91 and a shredder drum 92. A coarsely formed mixture from the fibre sources is delivered to the top of the housing and falls under gravity towards the squeeze rollers. The rollers counter rotate and urge the fibres onto the drum, after which the fibres flow from an exit at the foot of the housing, past a water mist sprayer 93. The surface of the drum has a relatively coarse structure which breaks down clumps of fibres. Preferably the surface of this drum is lined with V6 shredder wire and rotates at about 600φm.

Figure 10 provides more detail of the second opening stage 73 or 83 in Figure 7 or 8. The opener includes an upright housing 100 similar or the same as the opener in Figure 9. A passage within the housing feeds partially opened fibres from the first opener down to a combination of squeeze rollers 101 and a shredder drum 102. The rollers urge the fibres onto the drum as before, after which they flow from the foot of the housing past a water mist sprayer 103. The surface of the drum in this case has a relatively fine structure which further breaks down any clumps of fibres. Preferably the surface of this drum is lined with Vl 2 shredder wire and rotates at about 800rpm.

In relation to Figures 7-10, products formed in tests carried out to date used fibres having an average diameter in the range 9 to 14 microns. In one test glass fibres were blended at

50 to 90% by weight with the polymer melt fibres. In another test the resin powder was added at 5 to 25% by weight of glass fibres. The resulting products typically had a thermal rating R between 1.5 and 6. The products preferably have a loft between 90 and 220 mm, and a weight between 900 g/m² and 3 kg/m².

Claims

1. A method of forming a non- woven mat of fibres, including: forming a bed of fibres containing inorganic fibres blended from one or more fibre sources, feeding the bed into a first opener to form a mat having coarsely opened fibres, feeding the coarsely opened mat into a second opener to form a mat having finely opened fibres, and curing the finely opened mat; wherein the second opener includes a squeeze roller, nose bar, and a lickerin.

2. A method according to claim 1 wherein the first opener includes a squeeze roller, a nose bar, and a lickerin.

3. A method according to claim 1 wherein the first opener includes two opposed squeeze rollers and a lickerin.

4, A method according to claim 1 wherein the coarsely opened mat primarily contains randomised fibres without a visible regular structure and the finely opened mat primarily contains individualised fibres with a partly or wholly layered structure.

5. A method of forming a non- woven mat of fibres, including: forming a bed of fibres containing inorganic fibres blended from one or more fibre sources, feeding the bed into a first opener to form a mat of largely opened fibres, feeding the opened mat into a second opener to form a mat having multiple fibre layers, and curing the multiple layered mat.

6. A method according to claim 5 wherein the first and/or second opener includes a respective squeeze roller, nose bar, and lickerin.

7. A method according to claim 5 wherein the first and second openers include a squeeze roller having a rubberised surface and a carding surface respectively.

8. Apparatus for forming a non woven mat, including: a blender which forms a bed from one or more fibre sources, a first fibre opener which forms a coarsely opened mat from the bed, a second fibre opener which forms a finely opened mat from the coarsely opened mat, and an oven which cures the finely opened mat; wherein the second fibre opener includes a squeeze roller, nose bar, and a lickerin.

9. Apparatus according to claim 8 wherein the first fibre opener includes a squeeze roller, nose bar. and a lickerin.

10. Apparatus according to claim 8 wherein the first fibre opener includes two opposed squeeze rollers and a lickerin.

Ii . Apparatus according to claim 10 wherein the squeeze roller of the first opener has a rubberised surface and the squeeze roller of the second opener has a carding surface.

12. Apparatus according to claim 8 further including an anti static device such as a water sprayer between the first and second fibre openers.

13. A method of manufacturing a non woven insulation product, including: combining glass fibres with polymer melt fibres, opening the combined fibres in a two stage opening process, forming the combined glass fibres into a high loft matt, bonding the fibres in the matt by heating to melt the melt fibres, and forming the bonded matt into a product of required dimensions.

14. A method according to claim 13 wherein the first opening stage includes a rotating drum with relatively coarse carding wire and the second opening stage includes a rotating drum with relatively fine carding wire.

15. A method according to claim 13 wherein the glass fibres are Eglass with an average diameter in the range 9 to 14 microns.

16. A method according to claim 13 wherein the glass fibres are blended at 50 to 90% by weight with the polymer melt fibres.

17. A method of manufacturing a non woven insulation product, including: opening glass fibres in a two stage opening process, forming the opened glass fibres into a high loft mat, adding a resin powder to the mat, bonding the fibres in the mat by heating to melt the resin, and forming the bonded mat into a product of required dimensions.

18. A method according to claim 17 wherein the first opening stage includes a rotating drum with relatively coarse carding wire and the second opening stage includes a rotating drum with relatively fine carding wire.

19. A method according to claim 17 wherein the glass fibres are Eglass with an average diameter in the range 9 to 14 microns.

20. A method according to claim 17 wherein the glass fibres are blended at 50 to 90% by weight with the polymer melt fibres.

21. An insulation product manufactured using a two stage opening process andn having a thermal rating R between 1.5 and 6, a loft between 90 and 220 mm, and a weight between 900 g/m² and 3 kg/m².