CA2107266A1 - Production of sheet from polymer waste - Google Patents
Production of sheet from polymer wasteInfo
- Publication number
- CA2107266A1 CA2107266A1 CA 2107266 CA2107266A CA2107266A1 CA 2107266 A1 CA2107266 A1 CA 2107266A1 CA 2107266 CA2107266 CA 2107266 CA 2107266 A CA2107266 A CA 2107266A CA 2107266 A1 CA2107266 A1 CA 2107266A1
- Authority
- CA
- Canada
- Prior art keywords
- polymer
- waste
- polymer waste
- composite sheet
- reinforcement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000002699 waste material Substances 0.000 title claims abstract description 50
- 229920000642 polymer Polymers 0.000 title claims abstract description 40
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 6
- 239000002131 composite material Substances 0.000 claims abstract description 32
- 230000002787 reinforcement Effects 0.000 claims abstract description 30
- 239000012815 thermoplastic material Substances 0.000 claims abstract description 9
- 239000002184 metal Substances 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 22
- 229920001169 thermoplastic Polymers 0.000 claims description 15
- 238000007906 compression Methods 0.000 claims description 11
- 230000006835 compression Effects 0.000 claims description 11
- 239000004416 thermosoftening plastic Substances 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 6
- 229920005989 resin Polymers 0.000 claims description 6
- 239000011347 resin Substances 0.000 claims description 6
- 229920001187 thermosetting polymer Polymers 0.000 claims description 6
- 239000003365 glass fiber Substances 0.000 claims description 5
- 241000208202 Linaceae Species 0.000 claims description 3
- 235000004431 Linum usitatissimum Nutrition 0.000 claims description 3
- 230000000153 supplemental effect Effects 0.000 claims description 2
- 229910010272 inorganic material Inorganic materials 0.000 claims 1
- 239000011147 inorganic material Substances 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 10
- 238000003475 lamination Methods 0.000 abstract description 6
- 239000004743 Polypropylene Substances 0.000 description 13
- -1 polyethylene Polymers 0.000 description 12
- 229920001155 polypropylene Polymers 0.000 description 8
- 229920000098 polyolefin Polymers 0.000 description 5
- 239000004698 Polyethylene Substances 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 239000002657 fibrous material Substances 0.000 description 4
- 229920000573 polyethylene Polymers 0.000 description 4
- 239000003677 Sheet moulding compound Substances 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000009736 wetting Methods 0.000 description 3
- 101001044053 Mus musculus Lithostathine-1 Proteins 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000000748 compression moulding Methods 0.000 description 2
- 238000010924 continuous production Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 229920001684 low density polyethylene Polymers 0.000 description 2
- 239000004702 low-density polyethylene Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 230000032258 transport Effects 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 239000010791 domestic waste Substances 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000005188 flotation Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000002674 ointment Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
Landscapes
- Reinforced Plastic Materials (AREA)
- Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
- Laminated Bodies (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
Abstract
A B S T R A C T
PRODUCTION OF SHEET FROM POLYMER WASTE
Production of a composite sheet material from reclaimed polymeric waste of mixed origin, which may contain up to 75% wt of non-thermoplastic material, in which the waste is sintered and compressed onto a layer of fibrous reinforcement, optionally with lamination of a polymer or metal film onto one or both surfaces of the sheet.
PRODUCTION OF SHEET FROM POLYMER WASTE
Production of a composite sheet material from reclaimed polymeric waste of mixed origin, which may contain up to 75% wt of non-thermoplastic material, in which the waste is sintered and compressed onto a layer of fibrous reinforcement, optionally with lamination of a polymer or metal film onto one or both surfaces of the sheet.
Description
21~72~6 . 1 ~ PRODUCTION OF SHEET FROM POLYMER WASTE
.~
This invention relates to the re-use of polymeric waste in the production of a reinforced composite sheet.
The recycling and re-use of polymeric waste Ls an important aspect of current industrial polymer waste management programmes.
In addition to studies on the collection, separation and cleaning of polymeric materials from, e.g. municipal waste, it is important to develop effective processes for converting the reclaimed waste into resaleable outlets. Some applications have already been developed for specifically defined types of polymer, for example Wavin B.V. of The Netherlands produce household bags manufactured wholly from reclaimed polyethylene. However, when the polymer waste comprises a mixture of different polymers, and contains various undefined contaminants, as is usually the case in polymer waste material, it becomes very difficult to reprocess, e.g. by extruslon or in~ection moulding, into articles of commercially acceptable quality. Many attempts have been made to overcome these problems, including the deposition of granulated waste onto a conveyor, which transports it through an oven and then between compression rollers, to produce a board-like product (as described, for example, in U.K. patent specifications 1439353 and 2049540).
However, such products usually exhibit various deficiencies in mechanical and aesthetic propqrties which limi~ the extent of their commercial application.
Applicant has now found that composite sheet of quality which permits versatile application can be obtained by incorporating a 1~ fibrous reinforcement into sintered polymeric waste. AccordingIy, Z ~ in one embodiment, the present invention provides a process for the produc~ion of a composite sheet from reclaimed polymer waste which comprises: juxtaposing particulate polymer waste containing at least 25% wt. thermoplastic material with fibrous reinforcement ` ~ :
. . .
.
.,,~,; .
. , . ~
... ~ .
:~. .. .
21~2~6 located on a support surface, heating the polymer waste-coatsd reinforce~ent to a temperature sufficlent to soften the thermoplastic material, compresslng the heated, coated ~einforcement and cooling the resulting composite sheet, preferably under compression.
Naturally, a minimum level of thermoplastic componen~ is necessary in order to achieve satisfactory coating of the fibrous reinforcement, and, as indicated above, this is effectively 25~ wt.
of the total polymer waste, whilst higher proportions of thermoplastic component, i.e. at least 40% wt., will usually give a better wetting of the fibrous reinforcement and thence more uniform properties in the final composite sheet material. One of the important advantages of this process is that it operates effectively when the polymer waste contains significant proportions of non-melting materials, which should be in the form of ground particles and may be inorganic such as sand or glass (fibres) or organic such as thermosetting resins (which usually contain inorganic fibres such as glass fibre), and in fact the mechanical properties of the product benefit from a minor amount of ; 20 thermosetting resin. Preferably, therefore, the polymer waste contains, either initially or via supplemental addition, between 5%
wt and 25~ wt of thermosetting resin.
The actual chemical nature of the thermoplastic polymer waste, and of the thermosetting resin component (when present), may vary widely; this ability to process such a range of polymeric materials largely irrespective of their actual chemical nature and origin -being one of the significant advantages of the present procesa.
This polymer waste material is brought into particula~e form by established techniques for comminution of waste, such as shredding, grinding or granulation. Preferably the particle size is less than ,~ lO mm, suitably about 3-5 mm, with particularly good properties :
deriving from particles of flake form.
Any suitable fibrous material may be used for the reinforcement, but glass fibre has been found to yield composite sheet having particularly attractive physical properties. However, ~,",i~ ~ .
,~ ,..
} ~
, ~: .
.~
This invention relates to the re-use of polymeric waste in the production of a reinforced composite sheet.
The recycling and re-use of polymeric waste Ls an important aspect of current industrial polymer waste management programmes.
In addition to studies on the collection, separation and cleaning of polymeric materials from, e.g. municipal waste, it is important to develop effective processes for converting the reclaimed waste into resaleable outlets. Some applications have already been developed for specifically defined types of polymer, for example Wavin B.V. of The Netherlands produce household bags manufactured wholly from reclaimed polyethylene. However, when the polymer waste comprises a mixture of different polymers, and contains various undefined contaminants, as is usually the case in polymer waste material, it becomes very difficult to reprocess, e.g. by extruslon or in~ection moulding, into articles of commercially acceptable quality. Many attempts have been made to overcome these problems, including the deposition of granulated waste onto a conveyor, which transports it through an oven and then between compression rollers, to produce a board-like product (as described, for example, in U.K. patent specifications 1439353 and 2049540).
However, such products usually exhibit various deficiencies in mechanical and aesthetic propqrties which limi~ the extent of their commercial application.
Applicant has now found that composite sheet of quality which permits versatile application can be obtained by incorporating a 1~ fibrous reinforcement into sintered polymeric waste. AccordingIy, Z ~ in one embodiment, the present invention provides a process for the produc~ion of a composite sheet from reclaimed polymer waste which comprises: juxtaposing particulate polymer waste containing at least 25% wt. thermoplastic material with fibrous reinforcement ` ~ :
. . .
.
.,,~,; .
. , . ~
... ~ .
:~. .. .
21~2~6 located on a support surface, heating the polymer waste-coatsd reinforce~ent to a temperature sufficlent to soften the thermoplastic material, compresslng the heated, coated ~einforcement and cooling the resulting composite sheet, preferably under compression.
Naturally, a minimum level of thermoplastic componen~ is necessary in order to achieve satisfactory coating of the fibrous reinforcement, and, as indicated above, this is effectively 25~ wt.
of the total polymer waste, whilst higher proportions of thermoplastic component, i.e. at least 40% wt., will usually give a better wetting of the fibrous reinforcement and thence more uniform properties in the final composite sheet material. One of the important advantages of this process is that it operates effectively when the polymer waste contains significant proportions of non-melting materials, which should be in the form of ground particles and may be inorganic such as sand or glass (fibres) or organic such as thermosetting resins (which usually contain inorganic fibres such as glass fibre), and in fact the mechanical properties of the product benefit from a minor amount of ; 20 thermosetting resin. Preferably, therefore, the polymer waste contains, either initially or via supplemental addition, between 5%
wt and 25~ wt of thermosetting resin.
The actual chemical nature of the thermoplastic polymer waste, and of the thermosetting resin component (when present), may vary widely; this ability to process such a range of polymeric materials largely irrespective of their actual chemical nature and origin -being one of the significant advantages of the present procesa.
This polymer waste material is brought into particula~e form by established techniques for comminution of waste, such as shredding, grinding or granulation. Preferably the particle size is less than ,~ lO mm, suitably about 3-5 mm, with particularly good properties :
deriving from particles of flake form.
Any suitable fibrous material may be used for the reinforcement, but glass fibre has been found to yield composite sheet having particularly attractive physical properties. However, ~,",i~ ~ .
,~ ,..
} ~
, ~: .
3~:
2~7266 lt i~ also possible to use fibrous materials of naturally occurring, organic, origin - which can enhance the envlronmen~al acceptability of the resulting product; examples of such naturally occurring fibrous material are flax and ~ute. The chosen fibrous material may be used in any convenient format; thus, it may be chopped, relatively short, fibres, or relatively long (in relation to the width of the composite sheet being formed). ~lso, it may be laid onto the support surface as loose fibres, or may be formed into a self-supporting mat - either by compacting into a non-woven mat or by formation of a wovsn mat.
When the polymer waste contains a high proportion of thermo-plastic material, the sheet-forming conditions will usually cause sufficient impregnation and wetting of the fibrous reinforcement to produce a commercially useful product. However, the propertias of that composite sheet can be enhanced by lamination (on one or both surfaces) with a film of metal or polymeric material, such lamination being particularly beneficial when the polymer waste does not flow freely under the sheet-forming conditions (eg as a consequence of low thermoplastic content). The use of a metal film laminate will often require an adhesive to bond together the metal and polymer waste core (although sometimes the thermoplastic material itself may provide sufficient adhesion), and will, of course, modify both the physical and visual properties of the resulting composite, laminated sheet. The use of a polymeric film will also affect the visual propertles. However, a significant additional benefit from lamination is that the outer film serves to contain any loose fibres and also any chemical or biological contamination that may be present in the polymerlc waste. For reasons of operational aimplicity, it is normally preferred to use a thermoplastic polymer, e.g. a polyolefin such as polypropylene or polyethylene, for the film material.
A further modification of the process involves the use of two layers of fibrous reinforcement, conveniently but not necessarily of the same material, with the particulate polymeric waste being sandwiched between the two layers prior to heating and compression.
:` .
:
~ '~ .'' ' ' :
.
21!37266 In the preferred embodiment, ehls "twin-layer" variant is utilised in con~unction with lamination of a fil~ (preferably thermoplas~ic) onto upper~ lower, or both, surfaces(s) of the polymer-lmpregnated composite.
The process of this invention can be operated on a batch-type basis by the use of a compression mould into which the desired components are introduced in appropriate sequence. Thus, for a lam~nated "twin layer" composite sheet, the mould would be loaded with: i) thermoplastic film; ii) fibrous reinforcement; iii) particulate polymeric waste; iv) second layer of fibrous reinforcement; and v) second thermoplastic film. This laminate assembly would then be consolidated by the application of pressure accompanied by heating to a temperature sufficient to soften the thermoplastic component of the polymeric waste.
A more convenient mode of operation is, however, the (semi) continuous process wherein the support surface is a belt which conveys the fibrous reinforcement and the particulate polymer waste juxtaposed therewith through a heated space, between compression rollers, and through a cooling zone. The conveyor belt may be continuous or chain sections linked together, and is usually of . steel, through any other material meeting the requirements of flexibility/rigidity/heat resistance may be used. Al~o, it is often advantageous to have A non-stick coating (eg PTFE) on the upper surface of the belt, in order to aid release of the composite ' 25 sheet from the conveyor belt. The heaeing and compression stages ,~ need not be physically isolated from each other, but may overlap.
The cooling of ~he composite sheet will usually be carried out ~ whilst maintaining compression, becauae this reduces any tendency - of the fibrous reinforcement to expand (or "loft"). However, insome applications it may be more convenient to cool without `~, pressure, and subsequently form the composite sheet into shaped articles by compression moulding.
This conveyor belt process can, of course, readily be adapted to the "twin layer" format by feeding a second layer of fibrous reinforcement onto the layer of polymeric waste deposited onto the ; , ~ !
...'. i, ~ ,~ ` ........ .. .
. .
. i . . .
2~Q7266 first layer of fibrous relnforcement. Similarly, iE Rn outer fllm is to be laminated onto che composite sheet, this may be ~hrough an "in-line" operation in which the fLlm is fed directly onto the conveyor belt (if required on the under surface of the composite sheet), and/or onto the upper surface immediately prior to heating and compression. AIternatively, the laminating sheet(s) may be applied through a separate "off-line" lamination process.
The temperature of the heat treatment applied to the (laminar) composite should be sufficlent to soften the thermoplastic component of the polymeric waste, and thereby enable lt to flow around the reinforcement flbres and thence to wet them. The temperature should not of course, be so high as to cause significant thermal degradation of the polymer. Naturally, the exact temperature will depend on the components present in the polymeric waste material, and can be established for any chosen source of waste material by means of routine experimentation. In general, a suitable temperature will be between 140C to 220C, with 180-200C normally preferred. In general, higher pressures are more effective in producing better flow of polymer within the fibrous reinforcement, with enhanced wetting of the fibres, and also a flatter, more consistent sheet surface. However, operational and cost constraints normally impose a practical limit, - and the pressure employed to consolidate the heated composite of fibrous mat impregnated with softened polymer will normally be several bar, pressures of 3-5 bar usually being effective.
A further embodiment of the invention relates to the actual product formed by the process described above, and i9 a composite sheet comprising a fibrous reinforcement impregnated with reclaimed polymer waste material containing at least 25~ wt. thermoplastic material, and optionally laminated on one or both surfaces with a ~" film of metal or thermoplastic polymer, suitably polyolefin, such .:;
as polypropylene or polyethylene.
The invention is illustrated in the accompanying drawing Figure I which provides a diagrammatic representation of the ~` 35 embodiment wherein the particulate polymer waste is sandwiched ~: , ' 2i~07266 between two layers of flbrous reinforcement, and the composite is laminated on both the upper and lower surfaces with a film of thermoplastic polymer.
Referring to Figure I, a conveyor belt 1, suita~ly of steel, is ~oved by transport rollers 2 ln the direction indicated by the arrows. A film of thermoplastic polymer 3 is fed onto the conveyor belt, and a layer of fibrous reinforcement 4 fed onto that film 3.
Particulate polymer waste, stored in hopper 5 is then deposited from hopper 5 onto the layer of reinforcement 4, and a second layer of fibrous reinforcement 6 is fed onto the upper surface of the polymer waste. Finally, a second film of thermoplastic polymer 7 is fed onto the upper surface of the second layer of reinforcement 6, and the resulting laminar product conveyed by belt 1 through a heated space 8, between compression rollers 9, and through cooling lS zone 10. The resulting laminated composite sheet 11 is then : removed from conveyor belt 1 and either stored onto reels or cut into individual sheets according to established procedures. This composite sheet can then be formed into shaped articles by conventional stamping or mouldin~ processes.
. ~ 20 The continuous process described above is usually the most "
economic technique for commercislly producing the reinforced composite sheet on a large scale, but as indicated earlier, it is also possible to produce the reinforced composite laminated product in a batchwise operation by means of successive inserts into a .; 25 compression moulding press. That batchwise process was applied toproduce composite laminates as described in the following examples, ; which serve to illustrate the invention.
EXAMPLE
~:
~` Granules were prepared from mixtures of polymers selected to simulate a variety of differing polymer "waste" raw materials, and also from commercially available mixed plastic wastes with either ; ~
high or low polyolefin content. These were deposited onto a polypropylene film - supported layer of either glass fibre or of flax and covered with a second layer and film of the same materials. This laminate assembly was consolidated for 10 minutes ' .
2107~6 at 200C and a pressure of about 4 bar in a pre-heat~d moulding . press, and then cooled to room ~emperat~lre (without releasing pressure). Similar laminates were also produced using ~tainless steel covers in place of the polypropylene films with an adheslve of acrylic acid - modified polypropylene ("Polybond" 1001). The flexural strength and flexural modulus was measured according to ASTM D-790M. The results of these tests are tabulated below, together with, for comparative purposes, the corresponding - properties of virgin polyethylene, polypropylene, and glass fibre-reinforced polypropylene sheet co~mercially available from Symalit as "GM 30 PP".
In the following Table, the different components ~as ~ wt.) of the polymer waste are as follows:-` REPOWA 1:- Low density polyethylene 42.5% wt.
. 15 Polypropylene 34~ wt.
Polystyrene 8.5~ wt.
.i:
~: Sheet Moulding Compound ("SMC" Thermosetting resin, from : Citroen car bonnet) 15~ wt.
REG. 1:- Coarsely shredded high polyolefin content waste from de ~` ~ Vries, Heerhugowaard ; REG. lB:- as for REG 1 plus 15~ wt SMC
`~ 25 RECYCL:- A "heavy fraction" waste from AKW, being the residue after granulating, cleaning and flotation separation of (mainly bottle) domestic waste; having low polyolefin content and being predominantly in "flake" form.
`::
~ .
::
:
Table Flexural Properties . . .
Polymer Fibre Lamin- Sheet Modulus Strength Strain at Type Type ation Thick- (GPa) (MPa) Break ness (mm) (%) _ LDPE O.2-0.4 7-10 >5 PP 1.2-1.7 40-50 >5 - Glass Fibre Composite PP 3.8 88 3.7 REPOWA 1 GlassPP 3.8 3.1 58 3.6 : REPOWA 1 ll PP 6.1 3.2 49 3.0 REPOUA 1 ,. PP 6.2 3.0 50 3.2 REPOWA 1 Flax PP 6.5 4.5 43 2.6 REPOWA 1 GlassNone 5.9 4.2 54 2.5 REG 1 GlassPP 5.6 3.1 32 2.1 REG lB GlassPP 6.1 3.4 55 3.3 RECYCL GlassPP 5.5 4.9 67 2.1 ;
,:
,~
~.
"
. ~:
`~`:
' . ~
..:
;::
~ ' ,, .
.
; ` :
~ .
~::
2~7266 lt i~ also possible to use fibrous materials of naturally occurring, organic, origin - which can enhance the envlronmen~al acceptability of the resulting product; examples of such naturally occurring fibrous material are flax and ~ute. The chosen fibrous material may be used in any convenient format; thus, it may be chopped, relatively short, fibres, or relatively long (in relation to the width of the composite sheet being formed). ~lso, it may be laid onto the support surface as loose fibres, or may be formed into a self-supporting mat - either by compacting into a non-woven mat or by formation of a wovsn mat.
When the polymer waste contains a high proportion of thermo-plastic material, the sheet-forming conditions will usually cause sufficient impregnation and wetting of the fibrous reinforcement to produce a commercially useful product. However, the propertias of that composite sheet can be enhanced by lamination (on one or both surfaces) with a film of metal or polymeric material, such lamination being particularly beneficial when the polymer waste does not flow freely under the sheet-forming conditions (eg as a consequence of low thermoplastic content). The use of a metal film laminate will often require an adhesive to bond together the metal and polymer waste core (although sometimes the thermoplastic material itself may provide sufficient adhesion), and will, of course, modify both the physical and visual properties of the resulting composite, laminated sheet. The use of a polymeric film will also affect the visual propertles. However, a significant additional benefit from lamination is that the outer film serves to contain any loose fibres and also any chemical or biological contamination that may be present in the polymerlc waste. For reasons of operational aimplicity, it is normally preferred to use a thermoplastic polymer, e.g. a polyolefin such as polypropylene or polyethylene, for the film material.
A further modification of the process involves the use of two layers of fibrous reinforcement, conveniently but not necessarily of the same material, with the particulate polymeric waste being sandwiched between the two layers prior to heating and compression.
:` .
:
~ '~ .'' ' ' :
.
21!37266 In the preferred embodiment, ehls "twin-layer" variant is utilised in con~unction with lamination of a fil~ (preferably thermoplas~ic) onto upper~ lower, or both, surfaces(s) of the polymer-lmpregnated composite.
The process of this invention can be operated on a batch-type basis by the use of a compression mould into which the desired components are introduced in appropriate sequence. Thus, for a lam~nated "twin layer" composite sheet, the mould would be loaded with: i) thermoplastic film; ii) fibrous reinforcement; iii) particulate polymeric waste; iv) second layer of fibrous reinforcement; and v) second thermoplastic film. This laminate assembly would then be consolidated by the application of pressure accompanied by heating to a temperature sufficient to soften the thermoplastic component of the polymeric waste.
A more convenient mode of operation is, however, the (semi) continuous process wherein the support surface is a belt which conveys the fibrous reinforcement and the particulate polymer waste juxtaposed therewith through a heated space, between compression rollers, and through a cooling zone. The conveyor belt may be continuous or chain sections linked together, and is usually of . steel, through any other material meeting the requirements of flexibility/rigidity/heat resistance may be used. Al~o, it is often advantageous to have A non-stick coating (eg PTFE) on the upper surface of the belt, in order to aid release of the composite ' 25 sheet from the conveyor belt. The heaeing and compression stages ,~ need not be physically isolated from each other, but may overlap.
The cooling of ~he composite sheet will usually be carried out ~ whilst maintaining compression, becauae this reduces any tendency - of the fibrous reinforcement to expand (or "loft"). However, insome applications it may be more convenient to cool without `~, pressure, and subsequently form the composite sheet into shaped articles by compression moulding.
This conveyor belt process can, of course, readily be adapted to the "twin layer" format by feeding a second layer of fibrous reinforcement onto the layer of polymeric waste deposited onto the ; , ~ !
...'. i, ~ ,~ ` ........ .. .
. .
. i . . .
2~Q7266 first layer of fibrous relnforcement. Similarly, iE Rn outer fllm is to be laminated onto che composite sheet, this may be ~hrough an "in-line" operation in which the fLlm is fed directly onto the conveyor belt (if required on the under surface of the composite sheet), and/or onto the upper surface immediately prior to heating and compression. AIternatively, the laminating sheet(s) may be applied through a separate "off-line" lamination process.
The temperature of the heat treatment applied to the (laminar) composite should be sufficlent to soften the thermoplastic component of the polymeric waste, and thereby enable lt to flow around the reinforcement flbres and thence to wet them. The temperature should not of course, be so high as to cause significant thermal degradation of the polymer. Naturally, the exact temperature will depend on the components present in the polymeric waste material, and can be established for any chosen source of waste material by means of routine experimentation. In general, a suitable temperature will be between 140C to 220C, with 180-200C normally preferred. In general, higher pressures are more effective in producing better flow of polymer within the fibrous reinforcement, with enhanced wetting of the fibres, and also a flatter, more consistent sheet surface. However, operational and cost constraints normally impose a practical limit, - and the pressure employed to consolidate the heated composite of fibrous mat impregnated with softened polymer will normally be several bar, pressures of 3-5 bar usually being effective.
A further embodiment of the invention relates to the actual product formed by the process described above, and i9 a composite sheet comprising a fibrous reinforcement impregnated with reclaimed polymer waste material containing at least 25~ wt. thermoplastic material, and optionally laminated on one or both surfaces with a ~" film of metal or thermoplastic polymer, suitably polyolefin, such .:;
as polypropylene or polyethylene.
The invention is illustrated in the accompanying drawing Figure I which provides a diagrammatic representation of the ~` 35 embodiment wherein the particulate polymer waste is sandwiched ~: , ' 2i~07266 between two layers of flbrous reinforcement, and the composite is laminated on both the upper and lower surfaces with a film of thermoplastic polymer.
Referring to Figure I, a conveyor belt 1, suita~ly of steel, is ~oved by transport rollers 2 ln the direction indicated by the arrows. A film of thermoplastic polymer 3 is fed onto the conveyor belt, and a layer of fibrous reinforcement 4 fed onto that film 3.
Particulate polymer waste, stored in hopper 5 is then deposited from hopper 5 onto the layer of reinforcement 4, and a second layer of fibrous reinforcement 6 is fed onto the upper surface of the polymer waste. Finally, a second film of thermoplastic polymer 7 is fed onto the upper surface of the second layer of reinforcement 6, and the resulting laminar product conveyed by belt 1 through a heated space 8, between compression rollers 9, and through cooling lS zone 10. The resulting laminated composite sheet 11 is then : removed from conveyor belt 1 and either stored onto reels or cut into individual sheets according to established procedures. This composite sheet can then be formed into shaped articles by conventional stamping or mouldin~ processes.
. ~ 20 The continuous process described above is usually the most "
economic technique for commercislly producing the reinforced composite sheet on a large scale, but as indicated earlier, it is also possible to produce the reinforced composite laminated product in a batchwise operation by means of successive inserts into a .; 25 compression moulding press. That batchwise process was applied toproduce composite laminates as described in the following examples, ; which serve to illustrate the invention.
EXAMPLE
~:
~` Granules were prepared from mixtures of polymers selected to simulate a variety of differing polymer "waste" raw materials, and also from commercially available mixed plastic wastes with either ; ~
high or low polyolefin content. These were deposited onto a polypropylene film - supported layer of either glass fibre or of flax and covered with a second layer and film of the same materials. This laminate assembly was consolidated for 10 minutes ' .
2107~6 at 200C and a pressure of about 4 bar in a pre-heat~d moulding . press, and then cooled to room ~emperat~lre (without releasing pressure). Similar laminates were also produced using ~tainless steel covers in place of the polypropylene films with an adheslve of acrylic acid - modified polypropylene ("Polybond" 1001). The flexural strength and flexural modulus was measured according to ASTM D-790M. The results of these tests are tabulated below, together with, for comparative purposes, the corresponding - properties of virgin polyethylene, polypropylene, and glass fibre-reinforced polypropylene sheet co~mercially available from Symalit as "GM 30 PP".
In the following Table, the different components ~as ~ wt.) of the polymer waste are as follows:-` REPOWA 1:- Low density polyethylene 42.5% wt.
. 15 Polypropylene 34~ wt.
Polystyrene 8.5~ wt.
.i:
~: Sheet Moulding Compound ("SMC" Thermosetting resin, from : Citroen car bonnet) 15~ wt.
REG. 1:- Coarsely shredded high polyolefin content waste from de ~` ~ Vries, Heerhugowaard ; REG. lB:- as for REG 1 plus 15~ wt SMC
`~ 25 RECYCL:- A "heavy fraction" waste from AKW, being the residue after granulating, cleaning and flotation separation of (mainly bottle) domestic waste; having low polyolefin content and being predominantly in "flake" form.
`::
~ .
::
:
Table Flexural Properties . . .
Polymer Fibre Lamin- Sheet Modulus Strength Strain at Type Type ation Thick- (GPa) (MPa) Break ness (mm) (%) _ LDPE O.2-0.4 7-10 >5 PP 1.2-1.7 40-50 >5 - Glass Fibre Composite PP 3.8 88 3.7 REPOWA 1 GlassPP 3.8 3.1 58 3.6 : REPOWA 1 ll PP 6.1 3.2 49 3.0 REPOUA 1 ,. PP 6.2 3.0 50 3.2 REPOWA 1 Flax PP 6.5 4.5 43 2.6 REPOWA 1 GlassNone 5.9 4.2 54 2.5 REG 1 GlassPP 5.6 3.1 32 2.1 REG lB GlassPP 6.1 3.4 55 3.3 RECYCL GlassPP 5.5 4.9 67 2.1 ;
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Claims (10)
- C L A I M S
l. Process for the production of a composite sheet from reclaimed polymer waste which comprises: juxtaposing particulate polymer waste containing at least 25% wt. thermoplastic material with a fibrous reinforcement located on a support surface; heating the polymer waste-coated reinforcement to a temperature sufficient to soften the thermoplastic material; compressing the heated, coated reinforcement and cooling the resulting composite sheet. - 2. Process as claimed in claim 1 wherein the polymer waste contains, either initially or via supplemental addition, thermosetting resin and/or inorganic materials in an amount between 5% wt and 25% wt.
- 3. Process as claimed in claim 1 or 2 wherein the layer of fibrous reinforcement is glass fibre or flax or other naturally occurring fibrous product.
- 4. Process as claimed in claim 1, 2 or 3 wherein a second layer of fibrous reinforcement is deposited on the polymer waste-coated reinforcement.
- 5. Process as claimed in any one of the preceding claims wherein a film of polymer or metal is laminated onto at least one surface of the polymer-coated reinforcement.
- 6. Process as claimed in any one of the preceding claims wherein the support surface is a belt which conveys the fibrous reinforcement and the polymer waste juxtaposed therewith through a heated space, between compression rollers, and through a cooling zone.
- 7. Process as claimed in any one of the preceding claims wherein the heating is carried out at a temperature between 140-220°C for a period sufficient to soften the thermoplastic, and the compression is effected at a pressure of at least 3 bar.
- 8. Composite sheet prepared by a process as claimed in any one of claims 1 to 7.
- 9. Composite sheet comprising a fibrous reinforcement impregnated with reclaimed polymer waste material containing at least 25% wt thermoplastic material.
- 10. Composite sheet as claimed in claim 9 comprising additionally an outer film of thermoplastic polymer on both upper and lower surfaces.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP92308945 | 1992-10-01 | ||
| EP92308945.2 | 1992-10-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2107266A1 true CA2107266A1 (en) | 1994-04-02 |
Family
ID=8211502
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2107266 Abandoned CA2107266A1 (en) | 1992-10-01 | 1993-09-29 | Production of sheet from polymer waste |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH06190830A (en) |
| AU (1) | AU665456B2 (en) |
| CA (1) | CA2107266A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001032405A1 (en) * | 1998-04-03 | 2001-05-10 | Griffith Research And Development Enterprises Pty. Limited | Fibre reinforced thermoplastic composite |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102531610B1 (en) * | 2021-09-30 | 2023-05-11 | 주식회사 신흥 | Manufacturing method of fiber reinforced composite using powder of thermoplastic resin and fiber reinforced composite therefrom |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2415688A1 (en) * | 1978-01-25 | 1979-08-24 | Voisin & Pascal Carton | Hot-mouldable cardboard prodn. from reclaimed materials - esp. thermoplastics powder in core, with plant fibres and synthetic fibres in outer layers |
| IT1119064B (en) * | 1979-04-09 | 1986-03-03 | Rossi Livio Srl | PROCEDURE FOR THE USE OF RESIDUAL SLUDGE OF INDUSTRIAL PAINTING IN SPRAY CABINS WITH OVEN PAINTS |
| US4382108A (en) * | 1981-12-21 | 1983-05-03 | The Upjohn Company | Novel compositions and process |
-
1993
- 1993-09-29 CA CA 2107266 patent/CA2107266A1/en not_active Abandoned
- 1993-09-29 AU AU48714/93A patent/AU665456B2/en not_active Ceased
- 1993-09-29 JP JP26403093A patent/JPH06190830A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001032405A1 (en) * | 1998-04-03 | 2001-05-10 | Griffith Research And Development Enterprises Pty. Limited | Fibre reinforced thermoplastic composite |
Also Published As
| Publication number | Publication date |
|---|---|
| AU4871493A (en) | 1994-04-14 |
| JPH06190830A (en) | 1994-07-12 |
| AU665456B2 (en) | 1996-01-04 |
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