CA2060196A1 - Binder for absorbing oily liquids - Google Patents

Abstract

Wet polyolefin fibrils (10) of hydrophobic nature and cooled in water (24) are placed on a water-permeable tape (14) continuously circulating over at least two rollers (18, 20), where the water (24) drains off. The polyolefin fibrils are then guided to a heated roller (22) of large diameter. The fibres are dried to form a compact, tape-like nonwoven (28) on the surface (26) thereof, compressed and wound or cut into sections. The nonwoven is passed to a comminuting and disintegrating machine (32), in particular a hammer mill or a mixer, for impacting, after appropriate storage. A
loosened, flaked, hydrophobic pulp which has a large absorption capacity for oily liquids, for example crude oil or derivatives thereof, is thus produced. The flaked, hydrophobic pulp loosened by impacting has a greater absorption capacity than a nonwoven.
The polyolefin fibrils (10) of a binder are joined to one another at points by means of thermobonding.

Description

WO 91/17295 `~ ~J ,'3' ~ ; PCI'/EP~ 0818 Binder for absorbing oily liquids The invention relates to a pr~cess for manufacturing 2 recyclable binder made ~rom hydrophobic polymer fibres for absorbing crude oil and derivatives thereof or other oily liquids, from water, from a w2~er sur~ace or Erom the sround. The invention also relates to 2 re~ycla~l e binder made from hydrophobic ?olym2- iores.

Crude oil and derivatives the-eor, su_.~ as frc e~ampl2 neating Oll, alesel oil, petroi and o~her motor fuels, but also other oily substanc_a also re srread te n brl_-as oily liquids or oils in the 'e,; ;~niO'î follol~s, a e transported to land and water more and more frequently, in increasing amounts and in larger containers. Damage which may lead to environmental catastrophes is a threat in the event of an accident. However, damage, which -assumes a large dimension, may occur even in the case of smaller transport containers, if it cannot be prevented rapidly and using simple means. In this context, the oil fighters of local fire brigades, which have to take the first measures for the prever. ion o water pollut'on and protection of drinking water facilities, should be mentioned by way of example.

German Auslegeschrift 1 g39 490 describes fibre mixtures for limiting or eliminating contaminating oil from a water surface. The fibre mixture may contain plastic fibres. Polypropylene or polyetnylene fibres, even for coverin~ nets, are emphasised in particular. Finally, squee2ing out is mentioned fo- the re-use of absorDtion devices.

United States application 3 539 013 mentions that absorptlon pads made from polymer flbres, in particular : ' ,' :

WO 91/17295 . P~/EP91/0081Q
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polypropylene fibres of high density, ~hich are randomly orientate~, are used for absorbing oil. Special device features are described which relate to coverings, reinforcing ropes for coverings and the 1 i~e .

Experimen~s using a comparable make from the roll :
(~ULPLUS, a ~UPONT product) have shown that the absor?tion capacity of a compac. nonwoven is very limited for oil. T.hus it has been shown, for example that an amount ol oil, which corresponds approximately to the polyecnylene tapo nonwoven's own weight, may be absorbed 2 teL one hour of i~mersion in diesel oil and five minutes draining.
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The inventor is faced with the object of providing a process of the type mentioned in the introduction by means of which a binder, which may absorb many times its own weight of oily li~uid with a high retention capacity, is produced for absorbing oily liquids. The simple and -economical process should make available a binder which permits ecologically harmless recycling of the oily liquid cr removal.
: . '.' With respect to the process, the object is achieved .
according to the invention in that wet polyolefin fihrils cooled in water are placed on a water-permeable tape ~
continuously circulating over at least two rollers, `i:
guided on a heated roller of large diameter while , ,~
draining the water, dried on the surface thereof to fo~m a compact, tape-like nonwoven, then compressed and wound or cut into sections, which nonwoven i5 passed to a co~minuting or disintegrating machine for impacting, after appropriate storage, a loosened, flaked, hydrophobic pulp being produced ~hich has a large absorption capacity for oily liquids. Special embodiments and further developments of the invention are the object ; of~dependent patent claims.
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.WO91/17295 PCT/EP~1/00818 The compact, tape-like or cut starting nonwoven is preferably passed to a hammer mill or a mixer of conventional construction.

The polyolefin fibrils of the pulp flakes leaving a comminuting or disintegrating machine in the form of Elakes are prerera~ly joined to one another at points by melt adhesion, this is also termed thermobonding. A pulp thus a-t'calns a certain dimensional stability, even after --the aDsorption of oil it does not fall apart. However, the number of point adhesions is measured so that the pulp remalns expandable and the absorption capacity for oil ~s not reduced or is reduced only imperceptibly.

The point adhesion is carried out advantageously by partially melting fibrils in a hot stream of air or by contacting with at least one heating surface which may be a stationary (plate) or a moving (roller, belt) shaping surface.

The preferred temperature for the thermobonding known per se is in the range from 160 - 220C, which is advantageously used for 1 to 2 minutes to prevent the fibres from melting to too great an extent.

The pulp flakes may be joined together to form a flat pulp in accordance with processes known per se at the same time as or after thermobonding. This loosened flat pulp is preferably designed to be like a tape, also continuous, it may be wound or stacked folded, even after applying a tear-resistant outer shell.

The PULPLUS product from Messrs. DUPONT mentioned above is particularly suitable as a compact starting nonwoven of about 1 mm thickness. Experlments using loosened pulps arranged in an oil-permeable covering or having a flat "~
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shape manufac~ured according to the process of the present invention, have sho:~n t~.2t t~e oii absorption capacity is increased considerably using binders manufactured according to the inv~nt~ or.. ~er.-2, lor example a pulp made from polvethylene fibrils impacted using a hammer mill, absorbed app-o;~ima~e'~v .en times its own weisht oE diesel oil within just one houl aIteL five minutes draining.

The full aDsorption caDacity Ot a lccsenec ~UlD
manufactured according to tho i.~ventiGn is at least 15 times, preferably at least 20 to 30 times ~s cwn weioh~, the oily liquids being abso-~e~ w '-~ _0-. capaci-y.
However, no water an also no o.nar hvdrsDhiiic moisture or liquid is absorbed to a appreclable extent because of the hydrophobic nature of the polyolefin fibrils.~ :

The loosened pulp used as absorption material reacts differently depending on the nature and the viscosity of ~
the oil. The full absorption capacity may usually be ~' achieved after about 2 to 4 hours.

The polyolefin fibrils preferabiy consist of polyethylene --or polypropylene of high density, they are advantageously about 1 mm long and have a diameter of 1 - 20 ~m.

The solution of the invention is characterised with reference to the recyclable binder in that the polyolefin fibrils are joined to one another at points by means of thermobonding.

A pulp fully soaked with an oily liquid floating on a water sur~ace remains intertwined or linked, in as far as it is treated by means of thermobsnding, no powder or other oiI-soaked components sink. ~he pulp may be distributed intact or in larger pieces, and may be collected without difficulty for recycling or removal.
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The pulp is preferably designed as 2 flat layer and is stored as stacks or rolled up as a taDe and transported According to a pre~erred embodiment of the invention, 2 pulp is embedded in an all-round llquid-permeable, flexible outer shell or a net for impro~ed handling during storage, transport and belor~, during and after use and to achieve a greater mechar.ic21 resis~ance. This outer shell, nets are also sne'ls, ;s ~ear-resls~an~ and resistant to chemicals. It consists o. a nonwoven, textile, knitted fabric or ne-., prefer2~1y Maae from a ~las.~_, SUCl- aS foi ~xampie 2 polyester or polypropylene.

A flat pulp arranged in a shell may comprise one or more premanufactured layers. The shell must be able to expand several times as much when the oily liquid is absorbed, because of the large oil absorption capacity of the pulp.
The shell is therefore folded, for example like a bellows, either in pad or tube form. The shell further advantageously comprises at least one carrying or suspension device for manual or machine transport.

To prevent compression of the fibrils during transport they may be interspersed by a fine grain, neutral powder or by appropriate fibres, for example cellulose fibres treated with sand, polystyrene powder and/or treated to be water repellent. Here neutral means that neither the powder nor the fibres, which are used as a lining, are able to bind water or oil. Sand is also a weighting agent ~-for binders used on land.

The elements of the pulp are designed in dimensions such ~ : .
~ ~ that they may be carried by one or at the most two :
`people, even when fully soaked, for use on land, for example by oil fighters. For use cn water where work is carried out by machine, larger dimensions are possible ~ ~

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WO9l/l729C PCTtEP91/008'-~-~ n ~. ~`t ~
'-~and they are only limited by the tear resista~lce of the shell or its drawing reinforcements and susDensions.
Drawing reinforcements in the shell serve for pulling, for example t~o external wires, ropes or chains are integrated to be resistant to pulling, in particular for long elements.

Long sac,~s or tubes for the pulps are advantageously rormed ~3 ?osition a oil barrier, intermediate walls for the Iormation of chambers preferably being provided at`~
inter-v-al~. The intervals of the intermediate walls are pre~erably between 0.2 and l ~. This prever.ts the flowable a~so~ber oil mass from bulging ou. too much wnen the sacks or tubes, which may be continuous, are pulled out.

Shorter flat elements with the pulp arranged in a shell may also be preferably releasably connected to one another, or may be fitted with premanufactured devices ; for connecting to a couple of handles, for the formation of an oil barrier in water as well as on land. An oil fighting stand-by team has elements available which are ~ ;
advantageously connected to one another, these may be -carried before use without difficulty in larger, for -example rolled up or folded units. Of course individual units as well as open pulps may also be introduced as ;
barrier materlal. :
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`The shell of a flat element may also have fastening devices for means to hold, pull, float and-or weigh down, ~-next to or in addition to carrying or suspension devices.
For use on water, in particular for a moving surface, oil ~arriers are advantageously positioned so that they are not carried off course. Furthermore, it may be advantageous to attach floats to prevent sagging. For oil barriers on land, in particular on roads or squares having co1lecting channels and/or manholes, it may prove ;~

.WO91/1729; P~T/EP9~/0081~
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to be necessary to weigh down and/or to f ix the elements at critical points.

According to a further variant, elements having covered pulps made from polyolefin fibrils are arranged in the fiow cavity of a container having an inlet and an outlet to purify water contaminated with an oily liquid during rinsing. This method is particularly suitable for small amoun~s o~ oil in water.

The oil absorption pads can be used universally, they are reuui~d ror use evervwhere where crude oil or der~va'ives thereo' are l~sed, for example in petrol stations, in airports, intermediate stations of pipelines, tankers, garages, in the fire brigade, in -particular oil fightins and in civil defence.

The oil soaked up by the pulp can be recovered with lower recycling costs and can be re-used. The pulp raw materials can also be re-used many times without further expense af ter the oil has been removed.

The invention is explained in more detail using the exernplary em~odiments, which are also objects of the :
dependent patent claims, shown in the drawing.
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~ Figure-1 shows schematically the manufacture Xnown per : :
se of a compact tape made from polyethylene fibrils, ... .
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- Figure 2 shows schematically the principle of impacting this tape using a ha~mer mill, - Figure 3 shows schematically a tape-like loosened ~ :
nonwoven, ~- Figure 4 shows schematically a section through a covered, loosened polyolefin pulp, :. .
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WO91/17295 PCT/EP9l/00~' - Figure 5 shows schematically a view of a covered element having polyethylene fibrils, . .
Figure 6 shows schematical -~ a c oss-sa^tion Ih~ough Figure 5 at VI-VI
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- Figure 7 shows schematicallv a vie~ of an element folded like a bellows berore ~ sor3t 0e, - Figure 8 shows schematicall~ a SeCtlO~. hrous.h a.
element according to Figure 7 after oil abs~rD~ion, - Figure 9 shows schematicali~ a sec lon .rom an element designed as a continuous tube in lonsitudinal section, -and Figure 10 shows schematically a cross-section X-X
through the tube according to Figure 9.
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Figure 1 shows wet polyolefin fibrils 10, which are placed in direction 12 on a continuous, water-permeable tape 14. This tape 14 designed as a sieve runs in the direction of the arrow 16 arourd two rollers 18, 20, at least one of which is driven. The wet polyolefin fibrils drain initially on the tape 14, this is characterised by water droplets 24. The residual water of the wet polyolefin fibrils 10 is su~se~uently evaporated.

~he heart of the machine, which essentially ~orresponds to a pap~er manufacturing machine, is a heatable roller 22 which has a large diameter, usually about S - 10 m. The polyole~fin fibrils 10 are compressed to form a compact tapa on the surface of the roller. This tape has the same , characteristics as cardboard.

The compact tape nonwoven 28 leaving the roller surface 26 is wound onto a reel 30 and stored until it is used.

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W091/172~5 PCT/EP91/00818 The cardboard-like tape nonwoven 28 is impacted in a hammer mill characterised by an arrow 32 according to Figure 2. The individual fibres are exposed in this manner and form pulp flakes 34 havi~g a loose structure.

Figure 3 shows pulp flaXes 34 joined o a loosened pUl?
tape 36. The pulp flakes 34 are joined, for example using thermobonding, with the formation o-~ numero~s jolning points. The structure remains very loose and nence the absorption capacity for an ol! is lars~.

Figure 4 shows a bag ~8 or tube having an oute~ shell aQ
known per se and pe-meable to ~ da 2~ cr. ~ a adhered on three sides to form a hem 42. The structure of the enclosed pulp fla~es ~4 remains loose and ensures a ~-large absorption capacity for oil. - -Figures 5 and 6 show an element 44 which comprises several flat pulps or pulp tapes 3S layered one on another. These are held together by a shell 40 made from an all-round water-permeable nonwoven of tear-resistant plastic fibres. The pulps 36 are dry, hence they have not as yet absorbed any oil.

The two halves of the shell 40 form a surrounding hem 42 ~-which is formed from two watertight exterior shell sides adhered one on another.
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The upper hem 42 is broader, it may have a space reserved for a handle 46, which is shown by a dotted line. Of --course several handles 46 are also possible, in particular two. ~-Ovèrall the element 44 is flat, it may be stacked so as to take up a small volume and be transported. After absorbing an oily substance the shell 40 bulges out so far that the element 44 is virtually spherical.
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Figures 7 and 8 show an element 44 filled with pulp 36 and provided with a shell 40 before and after absorbing oil. The element 44 lying on the ground 50 h~s a side wall 48 fo!ded like a bellows and which is stretched slightly or completely when oil is absorbed.

A further one to six carrying flaps may be attached in the region of the upper part of the shell 40 (not shown).

Before use elements 44 joined to one another may be rolled up or folded, this saves space, pPrmits easy transDort and is suitable for s~reading out rapidly.
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Figure 9 shows an element 44 which is designed as a continuous tube. There is an intermediate wall 52 approximately every 50 cm, by means of which the chambers containing pulp 36 are formed. The pulp 36 is shown greatly enlarged in a chamber. In addition to the polyethylene fibrils 10, fine grain sand 54 can be seen which prevents the fibrils 10 from being compressed during transport.

It can also be seen from the cross-section according to F'igure lO, that the element 44 designed as a continuous tube floating on the water surface 56 having an oil film 60 has two lateral drawing reinforcements 56, which, for example are present in the form of a wire, a rope or a -chain.
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A continuous tube may be arran~ed, for example on a ship, which absorbs the oil resorbed by the surrounding tube.
Hence the tube may absorb and release several hundred times more oll from water 62, and this is a significant economic and ecological advance.

Claims (10)

Patent claims

1. Process for the manufacture of a recyclable binder made from hydrophobic polymer fibres for the absorption of crude oil, derivatives thereof or other oily liquids, from water (62), from a water surface (58) or from the ground (50), characterised in that wet polyolefin fibrils (10) cooled in water (24) are placed on a water-permeable tape (14) continuously circulating over at least two rollers (18, 20), guided on a heater roller (22) of large diameter while draining the water (24), dried on the surface (26) thereof to form 2 compact, tape-like nonwoven (28), then compressed and wound or cut into sections, which nonwoven (28) is passed to a comminuting or disintegrating machine (32) for impacting, after appropriate storage, a loosened, flaked, hydrophobic pulp being produced which has a large absorption capacity for oily liquids.

2. Process according to claim 1, characterised in that the compact nonwoven (28) made from polyolefin fibrils, preferably from polyethylene or polypropylene fibrils, is passed to a hammer mill (32) or a mixer.

3. Process according to claim 1 or 2, characterised in that the polyolefin fibrils of the loosened, flake-like pulp (34) are joined to one another partially at points by means of heat treatment, preferably in a hot stream of air or by contacting with at least one heating surface.

4. Process according to claim 3, characterised in that the thermobonding is carried out at a temperature of 160 to 220°C, preferably for 1 to 2 minutes.

5. Process according to one of claims 1 - 4, characterised in that the pulp flakes (34) are joined to form a loosened, tape-like pulp (36), preferably to form a continuous tape having an outer shell (40).

6. Recyclable binder made from at least one element (44) having a hydrophobic pulp (36) of intertwined and linked polyolefin fibrils (10) or high density and a diameter of less than 40 µm, which forms a fine-pored expandable cavity for absorbing crude oil and derivatives thereof or other oily liquids, from water (62), from a water surface (58) or from the ground (50), characterised in that the polyolefin fibrils (10) are joined together at points by means of thermobonding.

7. Binder according to claim 6, characterised in that the polyolefin fibrils (10) consist of polyethylene or polypropylene.

8. Binder according to claim 6 or 7, characterised in that the polyethylene fibrils (10) are approximately 1 mm long and have a diameter of 1 to 20 µm.

9. Binder according to one of claims 6 - 8, characterised in that at least one preferably flat pulp (36) is arranged in a liquid-permeable, flexible outer shell (40) or a net, which is tear-resistant, resistant to chemicals and has at least one carrying or suspension device (46), and preferably has intermediate walls (52) forming chambers at an interval of 0.2 to 1 m.

10. Binder according to claim 9, characterised in that the pulp (36) is continuously surrounded by the tear-resistant outer shell (38).