AU659335B2 - Non-woven, thermally-bonded fibre, compressed brush construction for caustic mill environments - Google Patents

Description

pry~lll~.m~u~'r~l~ PUFF~~Cn~L?-~-~ "NON-WOVbEN, THERMALLY- BONDED FIBRE, COMPRESSED BRUSH CONSTRUCTION FOR CAUSTIC MILL

ENVIRONMENTS".

Field of the Invention This invention relates to a non-woven thermal-bonded (or "melty") fibre compressed brush construction for caustic mill environments.

Background of the Invention Prior to electrolytic tin plating, steel strip must be thoroughly cleaned. This is done on a continuous basis in steel strip mills by passing Lhe strip through a hot caustic cleaning tank followed by hot water rinse tanks. Cleaning is aided by agitation of the surfaces using brushes.

Said brushes are commonly made from natural vegetable fibre bristles, e.g. tampico brushes which are made from a coarse grass-like plant grown in Mexico. They may also be of a synthetic construction, e.g. polypropylene bristles.

About 10 years ago. 3M Australia developed a non-woven compressed section cleaning brush which was found to have 2 to 3 times the service life of the tampico bristle brush.

This brush is made from an air laid randomly formed web from 13-15 denier nylon staple of length 38mm. The web is needletacked to increase its density and strength, thence thoroughly impregnated with a phenolic resin solution as binder and cured to give the required resistance to highly caustic conditions.

This type of brush construction has been utilised by BHP Tin Plate Mill for about the last 20 10 years. This phenolic bonded web brush, although its life was much superior to tampico, has been found to have the disadvantage of generating "fluff" by the gradual breakdown of the phenolic resin binder by the hot caustic conditions (typically pH 13 and 80°C). The "fluff" is caused by the release of the nylon staples of which approximately 17 million are present in the Snon-woven web sections used in a 406mm x 1200mm brush. This "fluff" is difficult to clean S 25 out of the steel mill cleaning lines and tends to block up filters.

Summary of the Invention Accordingly there is provided a non-woven, thermally-bonded polyolefin fibre web phe-ch.o having no resin binder.

Brief Description of the Drawings S 30 Fig. Plan view of typical non-woven section for tie-bolt construction.

Fig. Plan view of typical spacer for tie-bolt construction.

Fig. Exploded view of brush assembly showing sections, spacers, end flanges and tube bolts and screws.

Fig. Drawing of completed brush iri perspective view.

Fig. Plan view of typical non-woven section for bonded brush construction.

Fig. Plan view of typical spacer for bonded brush construction.

©Fig. Exploded view of brush and centre core to which sections and spacers are bonded.

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Fig. Drawing of completed brush in perspective view.

Best Mode and Other Embodiments of the Invention A non-woven thermally bonded polyolefin fibre web is made into a compressed brush as illustrated in Figures 1 and 2. Figures represents the brush and components with tiebolt construction features. Figures represents the same brush material utilized in a bonded brush construction. The web includes no resin binders. It is conceivable that such brushes could also be made into a flap brush type construction as well as the compressed section type. Spacers may not be essential in certain type brushes, for example, smaller ones.

The web can be produced from polyethylene/polypropylene staple in deniers from 3 to 40dn and lengths from 25mm to 64mm. A preferred range includes staple fibres of 38-50mm.

The nature of the fibre crimp could be conjugate or helical. Typically the fibres are thermoplastic bi-component, i.e. sheath and core type or side-by-side type, one component preferably being polypropylene and the other preferably polyethylene. Polyester bicomponent fibres may also be used. This construction allows melt bonding at the staple cross-over contact points, for example, by the lower melting point polyethylene component whilst the higher melting point polypropylene component maintains its dimensions and the web therefore has minimal shrinkage during bonding.

Usable webs for the brush construction can be made in web basis weights from 100gsm to 500gsm and web thickness of from 5mm to For additional web strength tensile and tear strengths) a needlepunching operation on the web before melt bonding has been found to be advantageous.

The abovementioned webs may be manufactured by using a RANDO WEBBER brand machine which produces a randomly woven ("non-woven") air laid web. Where needlepunching is deemed necessary, this is achieved by using a needle tacker machine fitted 25 with a multiplicity of needles, typically 15 x 18 x 30 x 3.5 CB Foster felting needles fitted to the needleboard.

After punching, the web is transported by conveyors through an oven heated to about 142°C for heat fusion, cooled and wound onto master rolls (termed "jumbos").

When sections 10, 20 are punched from the manufactured web "jumbos", they could be 30 of diameters 200mm to 600mm, depending on brush requirements and physical space in the cleaning lines. There is no real limit to brush length other than engineering design considerations.

The sections 10, 20 are formed with centre holes 70, 80 and cut with squared-off keyway slots 90 where required. Additional slots may be present to allow long tie-bolts 100 to hold the brush together between its end flanges (refer Fig. If a glued brush construction is required, tie bolts are not usd and the sections and spacers are adhered to a steel core 110 as shown in Figures The spacers 50, 60 (typically a thermoplastic such as polypropylene and with similar centre hole configuration but much smaller outside diameter) are ganged onto a dummy shaft and in a predetermined No./brush and sections/spacer ratio (typically 3:1) and compressed to [G:\WPUSERLIBMM10OO020:LMM 3 t make a dense non-woven brush that can be removed from the dummy shaft and loaded onto actual shafts in the steel mills.

The durometer of the finished brushes as measured by the Shore A2 scale is abt 5-25.

In a preferred construction of the present invention, the web was made from a "side-byside" bi-component staple fibre supplied by Chisso Corporation (Polypropylene Fiber Division, 6-32 Naqnoshima 3, Kita-Ku, Osaka 530, Japan) and termed Chisso Type ES. The preferred staple fibre i 18dn and length 64mm. The preferred web weight is 250gsm. The I web may be needlepunched at a punch density of 8 punches/cm 2 This is achieved by needletacking at 760 cycles/min and with a penetration of 21mm into the web.

A preferred brush construction 30, 40 comprises about 600 sections and about 200 (1.9mm thick) polypropylene spacers 50, 60 to form a 1.2m long x 406mm diameter compressed brush.

Section/spacer ratio in this brush is therefore 3:1 and loading is 12.5 lbrush length.

Brush loadings could however be in the range of 5 to 20 sections/25mm and section to ispacer ratios of from 1:0 to 5:1. The compacted densities of said brushes would be in the range 5-35kg/m 3 This brush, when run in the same hot caustic application as the conventional nylon/phenolic bonded brush, achieved a life extension of about 70% with significantly 1 20 reduced "fluff" generation and therefore about 350% life extension and reduced mill S maintenance compared with tampico bristle brushes.

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Claims (12)

1. A non-woven brush comprising: a plurality of compressed annular sections assembled about a centra carrier; the sections each comprising a mat of bi-component non-wovengfibres which have been crimped prior to melt bonding; the brush having a compacted density of from 5 to 35kg/m 3 wherein no phenolic binders are present in the sections.

2. The brush of claim 1, wherein: the fibres have been needlepunched prior to melt bonding.

3. The brush of either of claims 1 or 2, wherein: one component of the bi-component fibres is polypropylene.

4. The brush of claim 3, wherein: another component of the fibres is polyethylene.

The brush of any one of claims 1-4, wherein: each section has a basis weight from 100 to 500gsm.

6. The brush of any one of claims 1-5, wherein: the sections each have a diameter of from 200 to 600mm.

7. The brush of any one of claims 1-6, wherein: .the fibres are side-by-side type bi-component fibres having a denier of 3-40. 20

8. The brush of claim 7, wherein: the fibres have a staple length of 25-64mm.

9. The brush of any one of claims 1-8, wherein: spacers are interposed between at least some of the annular sections, the ratio of sections to spacers being from 1:0 to 5:1. 25

10. The brush of claim 8, wherein: the fibres have a staple length of 38-50mm.

11. The brush of claim 7, wherein: the denier is 18.

12. A brush, substantially as hereinbefore described with reference to the drawing figures. I Dated 19 August, 1993 3M Australia Pty Ltd Patent Attorneys for the Applicant/Nominated Person SPRUSON&FERGUSON WSR\ M100020:LMM *O I Non-Woven Cleaning Brush ABSTRACT A compacted non-woven, thermal-bonded brush is provided for use in caustic environments. The brush incorporates no phenolic binders. The brush comprises densified annular sections (10,20) which are assembled and compressed on a central core (100,110). Fig. 1(c) eah:9857N