CA2101646C - Recycled polyethylene construction product and method of manufacture - Google Patents
Recycled polyethylene construction product and method of manufacture Download PDFInfo
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- CA2101646C CA2101646C CA 2101646 CA2101646A CA2101646C CA 2101646 C CA2101646 C CA 2101646C CA 2101646 CA2101646 CA 2101646 CA 2101646 A CA2101646 A CA 2101646A CA 2101646 C CA2101646 C CA 2101646C
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- polyethylene
- oil
- mould
- mixture
- recycled
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
- B29B17/0026—Recovery of plastics or other constituents of waste material containing plastics by agglomeration or compacting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
- B29C39/02—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
- B29K2023/04—Polymers of ethylene
- B29K2023/06—PE, i.e. polyethylene
- B29K2023/0608—PE, i.e. polyethylene characterised by its density
- B29K2023/065—HDPE, i.e. high density polyethylene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
- B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
- B29K2105/08—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts of continuous length, e.g. cords, rovings, mats, fabrics, strands or yarns
- B29K2105/0809—Fabrics
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
- B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
- B29K2105/08—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts of continuous length, e.g. cords, rovings, mats, fabrics, strands or yarns
- B29K2105/10—Cords, strands or rovings, e.g. oriented cords, strands or rovings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
- B29K2105/26—Scrap or recycled material
-
- 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
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Mechanical Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Reinforced Plastic Materials (AREA)
- Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
Abstract
A cast recycled polyethylene product, optionally containing fibre reinforcement such as scrap polyester, contains oil as a compatibilizer. Typically the oil is derived from recycled containers. The product is made by comminuting containers, adjusting the oil content to the desired range, adding fibre reinforcement if desired, and heating the mix to a temperature sufficient for the polyethylene to commingle with the reinforcement if present, but insufficient to damage the fibers.
Typical cast products include guard rail posts, fence posts, highway median dividers, parking curbs, and the like. These products have the advantage of not being subject to weather damage and loss of structural strength, as is the case with timber and concrete.
Typical cast products include guard rail posts, fence posts, highway median dividers, parking curbs, and the like. These products have the advantage of not being subject to weather damage and loss of structural strength, as is the case with timber and concrete.
Description
TITLE OF THE INVENTION:
Recycled Polyethylene Construction Product and Method of Manufacture FIELD OF THE INVENTION
The present invention relates to a recycled polyethylene construction product and method for producing it. The method is particularly useful for utilizing disposable polyethylene containers, by employing a simple moulding technique.
1 o BACKGROUND OF THE INVENTION
The increasing costs of disposing of solid waste in landfill sites and recent concern over the longevity of material buried in such sites has prompted a search for alternative disposal methods, in particular the re-use of plastic materials. Additionally, increasing costs of oil-based plastic products have made the recycling of plastic products more economically i 5 attractive. A readily available source of high quality plastic is disposable polyethylene containers, such as lubricating oil containers, herbicide containers and many others. Recycled plastic can provide a useful construction material resisting weathering effects and salt degradation suffered by wood and concrete.
Recycled Polyethylene Construction Product and Method of Manufacture FIELD OF THE INVENTION
The present invention relates to a recycled polyethylene construction product and method for producing it. The method is particularly useful for utilizing disposable polyethylene containers, by employing a simple moulding technique.
1 o BACKGROUND OF THE INVENTION
The increasing costs of disposing of solid waste in landfill sites and recent concern over the longevity of material buried in such sites has prompted a search for alternative disposal methods, in particular the re-use of plastic materials. Additionally, increasing costs of oil-based plastic products have made the recycling of plastic products more economically i 5 attractive. A readily available source of high quality plastic is disposable polyethylene containers, such as lubricating oil containers, herbicide containers and many others. Recycled plastic can provide a useful construction material resisting weathering effects and salt degradation suffered by wood and concrete.
2 o In the past recycling of plastic products has been limited by contamination of the plastic material. Contaminants create difficulties in the recycling process, and can impair recycled product properties often in an unpredictable and random fashion.
Contaminants enter the recycle plastic stream as residual materials in the containers (from both the original contents, and other materials put into the container for disposal purposes), labels, tops, 25 undetected non-plastic material, and even debris from the processing equipment itself. Much effort is devoted to attempts to eliminate contaminants, by washing and by sorting materials for recycling. If an extruded or injection moulded product is to be made from the recycled plastic, then the feed material has to be substantially free of contaminants, as otherwise the expensive dies are at risk. Removing contaminants is not only time consuming and expensive, but also can produce additional environmental pollution, especially in the case of lubricating oil containers. Recycled plastic derived from feed material which has not been cleaned and sorted has generally been regarded as having inferior quality and only limited s usefulness.
SUMMARY OF THE INVENTION
The present invention provides a superior construction product obtained by a 1 o simple process which in many cases eliminates the need to wash the recycled polyethylene.
The process also does not require expensive plastic extrusion and injection moulding equipment. Residual lubricating oil often present as a residue in containers for recycling has been found to be an effective compatibilizer in recycling polyethylene material. Polyethylene is known to be a difficult plastic to recycle. Previous methods which have been suggested in 1 s the prior art for reprocessing it have required absorbent additives to counteract the effects of the residual oil. It has now been found that provided the amount of residual oil is kept to within a specific effective range, the plastic can be recycled into useful construction products without further treatment. If the proportion of residual oil in the recycled containers is too high, then dry, oil-free containers, such as herbicide containers and the like, or dry scrap 2 o polyethylene from other sources, must be blended in with the recycled containers to bring the oil level into the effective range. The inevitable other minor contaminants do not compromise the strength of the finished product.
As a further extension of the invention, it has been found that the addition of fibre 2 5 reinforcement, especially polyester fibres, notably increases the strength of the finished product. Fibre reinforcement is especially useful in larger products. The orientation of the fibres can be controlled to provide enhanced structural strength.
Contaminants enter the recycle plastic stream as residual materials in the containers (from both the original contents, and other materials put into the container for disposal purposes), labels, tops, 25 undetected non-plastic material, and even debris from the processing equipment itself. Much effort is devoted to attempts to eliminate contaminants, by washing and by sorting materials for recycling. If an extruded or injection moulded product is to be made from the recycled plastic, then the feed material has to be substantially free of contaminants, as otherwise the expensive dies are at risk. Removing contaminants is not only time consuming and expensive, but also can produce additional environmental pollution, especially in the case of lubricating oil containers. Recycled plastic derived from feed material which has not been cleaned and sorted has generally been regarded as having inferior quality and only limited s usefulness.
SUMMARY OF THE INVENTION
The present invention provides a superior construction product obtained by a 1 o simple process which in many cases eliminates the need to wash the recycled polyethylene.
The process also does not require expensive plastic extrusion and injection moulding equipment. Residual lubricating oil often present as a residue in containers for recycling has been found to be an effective compatibilizer in recycling polyethylene material. Polyethylene is known to be a difficult plastic to recycle. Previous methods which have been suggested in 1 s the prior art for reprocessing it have required absorbent additives to counteract the effects of the residual oil. It has now been found that provided the amount of residual oil is kept to within a specific effective range, the plastic can be recycled into useful construction products without further treatment. If the proportion of residual oil in the recycled containers is too high, then dry, oil-free containers, such as herbicide containers and the like, or dry scrap 2 o polyethylene from other sources, must be blended in with the recycled containers to bring the oil level into the effective range. The inevitable other minor contaminants do not compromise the strength of the finished product.
As a further extension of the invention, it has been found that the addition of fibre 2 5 reinforcement, especially polyester fibres, notably increases the strength of the finished product. Fibre reinforcement is especially useful in larger products. The orientation of the fibres can be controlled to provide enhanced structural strength.
The invention seeks to provide a substantially solid casting of recycled polyethylene suitable for numerous construction purposes. In a broad embodiment, the invention provides a heat cast recycled polyethylene product including substantially fused recycled polyethylene containing an effective amount of oil compatibilizer, preferably having embedded therein an effective amount of a compatible fibre reinforcement material.
There is considerable choice in the fibres which can be used as the reinforcement material. It is preferred to use polyester material, which is freely available in the form of 1 o scrap fabric and yarn. These fabric materials are primarily of polyester, often mixed with a proportion of other fibres, such as cotton or wool. A preferred fibre reinforcement is polyethylene terephthalate, commonly referred to simply as "polyester". In the preferred embodiment, the scrap polyester contains a major proportion of polyester blended with a minor proportion of another fibre.
Preferably, the recycled polyethylene is high density polyethylene (HDPE), or HDPE with not more than ten percent low density polyethylene (LDPE). In the preferred embodiment, at least 90% of the recycled polyethylene is high density polyethylene, HDPE.
Separating containers made from these materials is not difficult, since they are usually marked 2 o to show the polyethylene grade used. Minor amounts of other plastics may also be present.
The lubricating oil compatibilizer may be present as residual material in the recycled polyethylene containers. In the preferred embodiment, the oil compatibilizer comprises residual oil in at least some of the recycled containers, and more preferably, the residual oil is present in at least 50% of the recycled containers.
Polyethylene containers including residual oil preferably make up 50% of the polyethylene material.
Most preferably the construction product includes comminuted polyethylene containers present in a range from 90-98%, oil compatibilizer present in a range from 1-10%, and fibre reinforcement material, if desired, in a range from 1-8%, in each case by weight.
The product has proved particularly useful as a guard rail post, having an I-beam cross-section. The process according to the invention comprises the following steps:
- comminuting recycled polyethylene;
- blending oil with the comminuted polyethylene to provide a mixture containing an effective amount of oil;
- charging the mixture into a mould;
to - heating the filled mould to a temperature and for sufficient time for the mixture to become molten and substantially to fuse together;
- applying sufficient pressure to the contents of the mould to expel any trapped gas and any excess mixture;
- trimming any excess mixture forced out of the mould whilst still hot;
- rapidly cooling the mould in a cooling pond to an initial temperature at which the cast mixture can be handled;
- removing the casting from the mould; and - cooling the casting further in the cooling pond until fully solidified and cooled.
2 o Preferably the mixture contains an amount of fibres sufficient to provide reinforcement to the product, In that case, the mixture is heated to a temperature sufficient to cause the mixture to commingle with the fibre material, but insufficient to damage the fibre material. Thus if the reinforcement is polyester, the temperature is sufficient for the polyethylene to flow, but insufficient to melt the polyester. Typically, the mould is heated 2 s to a temperature of from about 130 to 160 degrees Celcius, but not more than 180 degrees Celcius.
Preferably the comminuted polyethylene contains from about I to about 10% of lubricating oil residues, comprising residues left in the containers after use. After the polyethylene has been comminuted it is easy to determine the oil content, for example by removing it with a solvent from a known this is weight of material. the oil level is too low, corrected by adding oil. If the oil level is too high, this is corrected by blending into the s mixture sufficient comminuted dry polyethylene substantially free of oil. It is often found that equal parts of dry oil free containers, and containers with oil residues left in them, provide just about the right amount of oil in the comminuted mixture.
Preferably, the particle size of the comminuted polyethylene is approximately 10 - 25 mm. long and 1 - 2 mm. square, which is about the thickness of the container wall. The polyester reinforcement generally is only present in larger cast products, but can be used in any size of product.
The mould is charged with an appropriate amount of comminuted polyethylene, oil, and, if necessary fibre reinforcement which is then compacted by hand, or by using vibration, to reduce cavities.
The mould containing the mixture of oil, comminuted plastic and, if desired, polyester reinforcement is held at the required temperature for an extended period of time, 2 o mainly because hot polyethylene is relatively viscous and flows quite slowly. For a massive product, such as a guard rail post, the time required can be as high as approximately 16 hours. That is, the mould is left heated overnight. A low pressure, approximately 5 psi or less, is conveniently applied to the mould by means of a cover, which may be contoured to form a shape in the top of the article. The pressure applied by the cover is sufficient to force 2s out at least the major proportion of any trapped air, and any excess material in the mould.
This excess is most conveniently removed from the mould whilst still hot, although trimming can be left and carried out as part of any final finishing steps, such as drilling holes, painting, and the like. The mould and its contents are cooled slowly in a cooling pond for thirty minutes to one hour, with the cover in place, to prevent warping.
Once removed from the mould the casting continues to cool in the cooling pond or an additional two hours.
Final trimming and finishing can be performed on the moulded article.
s The process precludes the need for expensive extruding equipment and injection moulds. Plastic articles produced by this method are ideally suited for use as guard rail posts, fence posts, highway median dividers, parking curbs, and the like where resistance to weathering and structural strength are required.
to As an example, a guard rail post is manufactured in a shaped steel mould, which, together with its cover, is contoured to provide a post with an 1-beam cross-section, according to the following procedure:
(i) equal parts of dry and oil containing high density polyethylene containers are comminuted and blended to thoroughly mix in the oil;
1 s (ii) a steel mould is charged with alternate layers of the oil-containing comminuted polyethylene and scrap polyester fabric, which is arranged longitudinally in the mould until 1/2 pound of fabric and 68 pounds of plastic have been added and compacted to fill the mould;
(iii) the charged mould is heated in an oven at 160 degrees Celcius for 16 hours;
20 (iv) the mould is removed from the oven, and the contoured cover is applied under a low pressure of approximately S psi to form the top shape and remove any excess air and plastic;
(v) any excess plastic is trimmed off whilst still hot;
(vi) the mould containing the hot casting is placed in a cooling pond for 1 /2 2s hour to initiate cooling without warping; and (vii) the formed post is removed from the mould and cooled in the cooling pond for an additional two hours.
The cooled cast post can then be drilled as final finishing to receive mountings for the guard rail.
s In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.
to It will be apparent to one skilled in the art that modifications may be made to the illustrated embodiment without departing from the spirit and scope of the invention as hereinafter defined in the Claims.
There is considerable choice in the fibres which can be used as the reinforcement material. It is preferred to use polyester material, which is freely available in the form of 1 o scrap fabric and yarn. These fabric materials are primarily of polyester, often mixed with a proportion of other fibres, such as cotton or wool. A preferred fibre reinforcement is polyethylene terephthalate, commonly referred to simply as "polyester". In the preferred embodiment, the scrap polyester contains a major proportion of polyester blended with a minor proportion of another fibre.
Preferably, the recycled polyethylene is high density polyethylene (HDPE), or HDPE with not more than ten percent low density polyethylene (LDPE). In the preferred embodiment, at least 90% of the recycled polyethylene is high density polyethylene, HDPE.
Separating containers made from these materials is not difficult, since they are usually marked 2 o to show the polyethylene grade used. Minor amounts of other plastics may also be present.
The lubricating oil compatibilizer may be present as residual material in the recycled polyethylene containers. In the preferred embodiment, the oil compatibilizer comprises residual oil in at least some of the recycled containers, and more preferably, the residual oil is present in at least 50% of the recycled containers.
Polyethylene containers including residual oil preferably make up 50% of the polyethylene material.
Most preferably the construction product includes comminuted polyethylene containers present in a range from 90-98%, oil compatibilizer present in a range from 1-10%, and fibre reinforcement material, if desired, in a range from 1-8%, in each case by weight.
The product has proved particularly useful as a guard rail post, having an I-beam cross-section. The process according to the invention comprises the following steps:
- comminuting recycled polyethylene;
- blending oil with the comminuted polyethylene to provide a mixture containing an effective amount of oil;
- charging the mixture into a mould;
to - heating the filled mould to a temperature and for sufficient time for the mixture to become molten and substantially to fuse together;
- applying sufficient pressure to the contents of the mould to expel any trapped gas and any excess mixture;
- trimming any excess mixture forced out of the mould whilst still hot;
- rapidly cooling the mould in a cooling pond to an initial temperature at which the cast mixture can be handled;
- removing the casting from the mould; and - cooling the casting further in the cooling pond until fully solidified and cooled.
2 o Preferably the mixture contains an amount of fibres sufficient to provide reinforcement to the product, In that case, the mixture is heated to a temperature sufficient to cause the mixture to commingle with the fibre material, but insufficient to damage the fibre material. Thus if the reinforcement is polyester, the temperature is sufficient for the polyethylene to flow, but insufficient to melt the polyester. Typically, the mould is heated 2 s to a temperature of from about 130 to 160 degrees Celcius, but not more than 180 degrees Celcius.
Preferably the comminuted polyethylene contains from about I to about 10% of lubricating oil residues, comprising residues left in the containers after use. After the polyethylene has been comminuted it is easy to determine the oil content, for example by removing it with a solvent from a known this is weight of material. the oil level is too low, corrected by adding oil. If the oil level is too high, this is corrected by blending into the s mixture sufficient comminuted dry polyethylene substantially free of oil. It is often found that equal parts of dry oil free containers, and containers with oil residues left in them, provide just about the right amount of oil in the comminuted mixture.
Preferably, the particle size of the comminuted polyethylene is approximately 10 - 25 mm. long and 1 - 2 mm. square, which is about the thickness of the container wall. The polyester reinforcement generally is only present in larger cast products, but can be used in any size of product.
The mould is charged with an appropriate amount of comminuted polyethylene, oil, and, if necessary fibre reinforcement which is then compacted by hand, or by using vibration, to reduce cavities.
The mould containing the mixture of oil, comminuted plastic and, if desired, polyester reinforcement is held at the required temperature for an extended period of time, 2 o mainly because hot polyethylene is relatively viscous and flows quite slowly. For a massive product, such as a guard rail post, the time required can be as high as approximately 16 hours. That is, the mould is left heated overnight. A low pressure, approximately 5 psi or less, is conveniently applied to the mould by means of a cover, which may be contoured to form a shape in the top of the article. The pressure applied by the cover is sufficient to force 2s out at least the major proportion of any trapped air, and any excess material in the mould.
This excess is most conveniently removed from the mould whilst still hot, although trimming can be left and carried out as part of any final finishing steps, such as drilling holes, painting, and the like. The mould and its contents are cooled slowly in a cooling pond for thirty minutes to one hour, with the cover in place, to prevent warping.
Once removed from the mould the casting continues to cool in the cooling pond or an additional two hours.
Final trimming and finishing can be performed on the moulded article.
s The process precludes the need for expensive extruding equipment and injection moulds. Plastic articles produced by this method are ideally suited for use as guard rail posts, fence posts, highway median dividers, parking curbs, and the like where resistance to weathering and structural strength are required.
to As an example, a guard rail post is manufactured in a shaped steel mould, which, together with its cover, is contoured to provide a post with an 1-beam cross-section, according to the following procedure:
(i) equal parts of dry and oil containing high density polyethylene containers are comminuted and blended to thoroughly mix in the oil;
1 s (ii) a steel mould is charged with alternate layers of the oil-containing comminuted polyethylene and scrap polyester fabric, which is arranged longitudinally in the mould until 1/2 pound of fabric and 68 pounds of plastic have been added and compacted to fill the mould;
(iii) the charged mould is heated in an oven at 160 degrees Celcius for 16 hours;
20 (iv) the mould is removed from the oven, and the contoured cover is applied under a low pressure of approximately S psi to form the top shape and remove any excess air and plastic;
(v) any excess plastic is trimmed off whilst still hot;
(vi) the mould containing the hot casting is placed in a cooling pond for 1 /2 2s hour to initiate cooling without warping; and (vii) the formed post is removed from the mould and cooled in the cooling pond for an additional two hours.
The cooled cast post can then be drilled as final finishing to receive mountings for the guard rail.
s In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.
to It will be apparent to one skilled in the art that modifications may be made to the illustrated embodiment without departing from the spirit and scope of the invention as hereinafter defined in the Claims.
Claims (23)
1. A heat cast recycled polyethylene product made by the process comprising:
comminuting polyethylene derived from recycled polyethylene containers;
blending oil compatibilizer, derived from residual oil in the recycled polyethylene containers, with the comminuted polyethylene until the oil in the mixture is between 1%
and 10% by weight, adding oil if the oil level is too low and adding comminuted polyethylene substantially free of oil if the oil level is too high;
charging the mixture into a mould;
heating the filled mould to a temperature and for sufficient time for the mixture to become molten and substantially to fuse together;
applying sufficient pressure to the contents of the mould to expel any trapped gas and any excess mixture;
trimming any excess mixture forced out of the mould whilst still hot;
cooling the mould in a cooling pond to an initial temperature at which the cast mixture can be handled;
removing the cast product from the mould; and cooling the casting further in the cooling pond until fully solidified and cooled.
comminuting polyethylene derived from recycled polyethylene containers;
blending oil compatibilizer, derived from residual oil in the recycled polyethylene containers, with the comminuted polyethylene until the oil in the mixture is between 1%
and 10% by weight, adding oil if the oil level is too low and adding comminuted polyethylene substantially free of oil if the oil level is too high;
charging the mixture into a mould;
heating the filled mould to a temperature and for sufficient time for the mixture to become molten and substantially to fuse together;
applying sufficient pressure to the contents of the mould to expel any trapped gas and any excess mixture;
trimming any excess mixture forced out of the mould whilst still hot;
cooling the mould in a cooling pond to an initial temperature at which the cast mixture can be handled;
removing the cast product from the mould; and cooling the casting further in the cooling pond until fully solidified and cooled.
2. A product according to claim 1, further comprising an effective amount of fibre reinforcement material.
3. A product according to claim 1 wherein residual oil is present in at least 50% of the recycled polyethylene containers.
4. A product according to claim 1 wherein the major proportion of the recycled polyethylene is high density polyethylene, HDPE.
5. A product according to claim 4 wherein at least 90% of the recycled polyethylene is high density polyethylene, HDPE.
6. A product according to claim 2, wherein the fibre reinforcement material is scrap polyester in the form of fabric or yarn.
7. A product according to claim 6, wherein the polyester is polyethylene terephthalate.
8. A product according to claim 6, wherein the scrap polyester contains a major proportion of polyester blended with a minor proportion of another fibre.
9. A product according to claim 1 containing in percentages by weight from 90-98%
polyethylene; and from 2-10% oil compatibilizer.
polyethylene; and from 2-10% oil compatibilizer.
10. A product according to claim 2 containing in percentages by weight from 90-98%
polyethylene; from 1-10% oil compatibilizer; and from 1-8% fibre reinforcement material.
polyethylene; from 1-10% oil compatibilizer; and from 1-8% fibre reinforcement material.
11. A process for producing a cast recycled polyethylene product comprising the steps of:
- comminuting polyethylene derived from recycled polyethylene containers;
- blending oil compatibilizer, derived from residual oil in the recycled polyethylene containers, with the comminuted polyethylene until the oil in the mixture is between 1% and 10% by weight, adding oil if the oil level is too low and adding comminuted polyethylene substantially free of oil if the oil level is too high;
- charging the mixture into a mould;
- heating the filled mould to a temperature and for sufficient time for the mixture to become molten and substantially to fuse together;
- applying sufficient pressure to the contents of the mould to expel any trapped gas and any excess mixture;
- trimming any excess mixture forced out of the mould whilst still hot;
- cooling the mould in a cooling pond to a temperature at which the cast mixture can be handled;
- removing the casting from the mould; and - cooling the casting further in the cooling pond until fully solidified and cooled.
- comminuting polyethylene derived from recycled polyethylene containers;
- blending oil compatibilizer, derived from residual oil in the recycled polyethylene containers, with the comminuted polyethylene until the oil in the mixture is between 1% and 10% by weight, adding oil if the oil level is too low and adding comminuted polyethylene substantially free of oil if the oil level is too high;
- charging the mixture into a mould;
- heating the filled mould to a temperature and for sufficient time for the mixture to become molten and substantially to fuse together;
- applying sufficient pressure to the contents of the mould to expel any trapped gas and any excess mixture;
- trimming any excess mixture forced out of the mould whilst still hot;
- cooling the mould in a cooling pond to a temperature at which the cast mixture can be handled;
- removing the casting from the mould; and - cooling the casting further in the cooling pond until fully solidified and cooled.
12. A process according to claim 11, wherein prior to the charging step an effective amount of fibre reinforcement material is incorporated with the blended mixture.
13. A process according to claim 11, wherein the recycled polyethylene is comminuted to a particle size of 10-25mm × 1-2mm square.
14. A process according to claim 11, wherein the major proportion of the recycled polyethylene is high density polyethylene, HDPE.
15. A process according to claim 14, wherein at least 90% of the recycled polyethylene is high density polyethylene, HDPE.
16. A process according to claim 12, wherein the fibre reinforcement material comprises scrap polyester in the form of fabric or yarn.
17. A process according to claim 16, wherein the scrap polyester is polyethylene terephthalate.
18. A process according to claim 16, wherein the scrap polyester contains a major proportion of polyester blended with a minor proportion of another fibre.
19. A process according to claim 11 wherein the filled mould is heated to a temperature of from about 130 - 180 degrees Celcius.
20. A process according to claim 19 wherein the temperature is from about 130 -degrees Celcius.
21. A process according to claim 11 wherein the pressure applied to the mould is 5 psi or less.
22. A process according to claim 11 wherein the mixture in the mould comprises in percentages by weight from 90-98% polyethylene; and from 2-10% oil compatibilizer.
23. A process according to claim 12 wherein the mixture in the mould comprises in percentages by weight from 90 - 98% polyethylene; from 1 - 10% oil compatibilizer, and from 1 - 8% fibre reinforcement material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2101646 CA2101646C (en) | 1993-07-29 | 1993-07-29 | Recycled polyethylene construction product and method of manufacture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2101646 CA2101646C (en) | 1993-07-29 | 1993-07-29 | Recycled polyethylene construction product and method of manufacture |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2101646A1 CA2101646A1 (en) | 1995-01-30 |
| CA2101646C true CA2101646C (en) | 2006-10-03 |
Family
ID=4152010
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2101646 Expired - Fee Related CA2101646C (en) | 1993-07-29 | 1993-07-29 | Recycled polyethylene construction product and method of manufacture |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2101646C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023218220A1 (en) * | 2022-05-10 | 2023-11-16 | Azuola Andrei Gaggion | High temperature repolymerization recycling and plastics |
-
1993
- 1993-07-29 CA CA 2101646 patent/CA2101646C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023218220A1 (en) * | 2022-05-10 | 2023-11-16 | Azuola Andrei Gaggion | High temperature repolymerization recycling and plastics |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2101646A1 (en) | 1995-01-30 |
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