5FIELD OF INVENTION

The present invention discloses a process of recycling plastic laminates. More specifically, the disclosed process is capable of separating the various material composing the laminates based on density of the material without costing much effort.

10BACKGORUND OF THE INVENTION

Owing to its excellent chemical inertness and insulating property, multiply plastic packaging materials are widely used as packaging material for wrapping various types of products. For example, electronic components such as IC board, chips and the like are normally wrapped in multiply plastic packaging materials to avoid unnecessary damage caused by static or

15oxidation during transportation. Similarly, food or other domestic products also prepared in packages derive from multiply plastic packaging material to prevent decomposition of the product or possibly degradation of the package made of other materials due to chemical reaction between the packaging material and the wrapped products. Normally, sheets of polyethylene terephthalate (PET) and oriented polypropylene (OPP) are laminated together in

201ayers to form the multiply plastic packaging material. Optionally, a thin aluminium sheet is incorporated into the multiply plastic packaging material to render additional light protection to the wrapped products as the aluminium sheet functions as a light impenetrable barrier. Nonetheless, increased consumption of the multiply plastic packaging materials concurrently triggers environmental pollution as materials like PET and OPP require great span of time to

25be degraded if being disposed without extra treatment, while incineration of such materials will release environmental polluting gases. Consequently, another feasible solution is recycling the multiply plastic packaging materials to be reused.

Patent application no.W09427818 provides a method for recovering aluminum from a 301aminate product containing aluminum. In the disclosed method, the laminates are heated until melted for recovering the aluminum which the laminates needed to contain aluminum weight equal or less than the weight of organic content.

United Patent application no.5358184 discloses a method for recycling multiply material used 5 for packaging by feeding the multiply material to chute through an auger which the multiply material is pre-soaked within the chute, transferring the pre-soaked multiply material into a chamber, subjecting the multiply material to high pressure liquid to separate the multiply into different sheets, separating the plastic sheet from the paper sheet through filtration. lOAnother United State patent publication no.2004129372 claims a method for recycling foil- laminated material comprising the steps of soaking the foil-laminated material in an acid solution to achieve the separation of the foil-laminated material by dissolving the alumina at the interface followed by cleaning and drying the recovered sheets.

15In United State patent publication no.2006178442, another method for recycling multi-layer packaging film waste is disclosed. According to the disclosed method, the multi-layer film is at first pulverized prior to be soaked in a solution for dissolving the aluminum, followed by separating the remaining sheets according their density through another solution, finally drying the remaining sheets.

20

SUMMARY OF THE INVENTION

The preset invention provides a process for recycling plastic laminates. Through the disclosed process, the laminated sheets of various materials can be separated and readily to be reused upon proper segregation.

5

In another object, the present invention offer an effective way to segregate various split sheets of a plastic laminate using liquid medium. More specifically, the present invention is able to conveniently segregate various composite materials forming the laminates based on density differences among the material and the liquid medium employed.

0 Further object of the present invention aims to disclose a system of recycling plastic laminates employing the abovementioned process.

At least one of the preceding objects is met, in whole or in part, by the present invention, in 5which one of the embodiment of the present invention is a process of recycling plastic laminates comprising the steps of reacting the plastic laminates with an acidic solution at a pH of 1 to 5; wherein the plastic laminates have layers made of any combination of polyethylene sheet, polyethylene terephthalate sheet, oriented polypropylene sheet and foil; splitting the plastic laminates to respective polyethylene sheet, polyethylene terephthalate lOsheet, oriented polypropylene and/or foil; washing the derived polyethylene sheet, polyethylene terephthalate sheet, oriented polypropylene and/or foil in a water passage filled with a flowing water that the aluminium sheets sink to the bottom of the passage and being collected thereof; and separating the polyethylene sheet, oriented polypropylene and/or polyethylene terephthalate sheet in a soap bath or salt water which the polyethylene sheets

15and the polyethylene terephthalate sheets or oriented polypropylene are collected at top and bottom of the soap bath or salt water respectively.

In another aspect, the process may include of drying the collected polyethylene sheets with an air blower and melting the polyethylene sheets for reuse. In order to enhance the reactivity 0of the acidic solution gains the soaked plastic laminates, it is preferable in the present invention that the plastic laminates is shattered or fragmentized to pieces of smaller size prior to the reacting step.

Still another embodiment of the present invention is a system of recycling plastic laminates 5applying the mentioned process. The system comprises a first tank for reacting plastic laminates with an acidic solution at a pH of 1 to 5; wherein the plastic laminates have layers made of any combination of polyethylene sheet, polyethylene terephthalate sheet, oriented polypropylene sheet and foil; an extruder receiving the reacted plastic laminates from the first tank and splitting the plastic laminates to respective polyethylene sheet, polyethylene 0terephthalate sheet, oriented polypropylene and/or foil; a water passage filled with moving water flow washing the split polyethylene sheet, polyethylene terephthalate sheet, oriented polypropylene and/or foils derived from the extruder that the foil sinks to the bottom of the passage and being collected thereof; and a second tank equipped with soap bath or salt water for separating the washed polyethylene sheet, polyethylene terephthalate sheet and/or 5oriented polypropylene disposed therein, wherein the polyethylene sheets and the polyethylene terephthalate sheets or oriented polypropylene are collected at top and bottom of the soap bath or salt water respectively.

In another embodiment, an air blower is incorporated at the downstream of the second tank lOto dry the collected polyethylene sheet. Preferably the fragmentized polyethylene sheets are blown through a conduit for collection at the end of the conduit while the remaining liquid is vaporized. To shatter or fragmentize the plastic laminates, a crusher is preferably positioned at the upstream of the first tank to shatter the plastic laminates prior to reacting with the acidic solution.

15

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a flowchart showing the different steps can be performed in one embodiment of the disclosed process to split and segregate the different laminated materials.

0

DETAILED DESCRIPTION OF THE INVENTION

One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiment describes herein is not intended as limitations on the scope of the 5invention.

The present invention involves a process of recycling plastic laminates comprising the steps of reacting the plastic laminates with an acidic solution at a pH of 1 to 5; wherein the plastic laminates have layers made of any combination of polyethylene sheet, polyethylene 0terephthalate sheet, oriented polypropylene sheet and foil; splitting the plastic laminates to respective polyethylene sheet, polyethylene terephthalate sheet, oriented polypropylene and/or foil; washing the derived polyethylene sheet, polyethylene terephthalate sheet, oriented polypropylene and/or foil in a water passage filled with a flowing water that the aluminium sheets sink to the bottom of the passage and being collected thereof; and 5separating the polyethylene sheet, oriented polypropylene and/or polyethylene terephthalate sheet in a soap bath or salt water which the polyethylene sheets and the polyethylene terephthalate sheets or oriented polypropylene are collected at top and bottom of the soap bath or salt water respectively. lOIt was found by the inventor of the present invention that the acidic solution in the present invention is an effective stripping agent to rid the adhesive binding each layers forming the multiply plastic laminates. In the preferred embodiment, the stripping agent is, but not limited to, acetic acid and/or formic acid. Amount of the acid to be utilized relies on reactivity of the types of acid used. In order to function in optimal condition, the pH of the stripping agent is

15preferably in the range of 1 to 5, while reaction time can be 5 to 60 minutes. To enhance the stripping rate, mild heating is employed in the present invention. Preferably, the stripping agent is heated to a temperature of 65°C to 90°C together with the plastic laminates. Nonetheless, mild stirring can be applied in the reacting step to facilitate dissolution the glue binding the laminated sheets but also slightly split the laminated sheets.

0

The acidic solution may only partially digests the binding adhesive of the plastic laminates and ease the splitting of the bound sheets thereafter. It is possible to manually split the sheets manually by hand or any other splitting means commercially available. For example, the splitting means can be a rotating wheel having spiky projection located at its surface. This 5rotating wheel is preferably located on top of a pool of water and slightly submerged in to the water. The reacted plastic laminates is disposed into the pool of water and crashed by the rotating wheel. Bringing down to the bottom of the water flow by the spiky projection generates a sheering force that splits the plastic laminates into different laminate sheet, preferably polyethylene sheets, polyethylene terephthalate (PET) sheets and/or oriented 0polypropylene (OPP) sheets and/or foils. In a more preferable embodiment, the splitting means is an extruder machine that the reacted plastic laminates are fed into the extruder. The extrusion force generates friction between the laminated sheets that the friction splits the completely or partially digested plastic laminates into individual sheets composing the plastic laminates. The extrusion force also presses the residue of the acidic solution out of the plastic 51aminates and the split individual sheets. The split individual sheet derived from the plastic laminates can be any combination of polyethylene sheet, polyethylene terephthalate (PET) sheet, oriented polypropylene (OPP) sheet and foil.

The mixture of individual sheets are later moved into a stream of flowing water in a water lOpassageway for segregation. Conventional way to group the split individual sheet is time consuming, while the inventor of the present invention has found an effective way to achieve the segregation. Mixed split individual sheets are placed into the flowing water at one end of the passage way and being carried to another end of the water passageway. The flowing water washes away the residues of glue or digested binding adhesive in this process. Owing to its

15higher density than the water, the foil, if presence, sinks to the bottom of the water passage way. The fallen foil is collected thereof from the bottom for reuse or recycle. More preferably, the water passageway has sufficient length to allow sedimentation of the foil to occur yet the water flow is moving at substantial slow rate to avoid forming of water turbulence in the water that prohibits the foil from sinking. The foil herein refers to 0aluminium foil or any other derivatives thereof. Nonetheless, the polyethylene terephthalate sheets and/or oriented polypropylene sheet with higher density than the water shall fall to the bottom of the water passage as well if left in a still water for sufficiently long time. Assisted by the water flow, these polyethylene terephthalate sheets and/or oriented polypropylene sheets treated in the present invention are carried to the end of the water passage for recovery 5before these sheets actually sink to the bottom.

Subsequently, the leaving individual sheets of polyethylene sheet, polyethylene terephthalate (PET) sheet, and/or oriented polypropylene (OPP) sheet are collected at the end of the water passageway and transferred into a soap bath or salt water. The soap bath or salt water may be 0produced from an known commercial available soap composition or any other alkaline solution alike dissolved into an aqueous phase. The soap or alkaline salt compounds dissolved into the aqueous phase increase density of the aqueous phase, water, that it can be used in the present invention to sort the of polyethylene sheet, polyethylene terephthalate (PET) sheet, and/or oriented polypropylene (OPP) sheet. The soap bath or salt water shows 5 greater significance difference in term density compared to polyethylene sheet rendering it better medium to segregate the individual sheets. In more detail, the low density and/or medium density polyethylene sheet used in the plastic laminates normally has density around 950kg/m ³ akin to water in room temperature. Segregation of the individual sheets using water in the process may not be effective due to the nearly similar density for both water and the lOpolyethylene sheet. It was found by the inventor of the present invention that salt water or soap bath, which has relatively higher density than pure water, shows better sorting power to separate the polyethylene sheet from the polyethylene terephthalate (PET) sheet and/or oriented polypropylene (OPP) sheet. The salt water or bath soap used in the disclosed process has density in between the polyethylene sheet and the polyethylene terephthalate (PET) sheet

15and/or oriented polypropylene (OPP) sheet. The polyethylene sheet with relatively lower density in the salt water or soap bath float on top of the stated aqueous medium., while the polyethylene terephthalate (PET) sheet and/or oriented polypropylene (OPP) sheet with higher density sinks to the bottom of the soap bath or salt water. Through the use of salt water or soap bath, the disclosed process can sort the individual sheets with ease yet incurring 01ess operational cost in view of reusability of the given liquid medium. Preferably, the salt used in the present invention are those neutral salts like sodium chloride, potassium chloride, or any other those commercially available. Nevertheless, other slightly acidic or alkaline salts are applicable in the present invention as well. More preferably, sodium triphosphate is employed to achieve better separation.

5

For transferring the separated polyethylene sheets for storing, the collected sheets are preferably dried. Thus the disclosed process may further include a step of drying the collected polyethylene sheets with an air blower. More specifically, the collected polyethylene sheets are placed in a duct connected to a storage space that strong air flow is passing through the duct. The strong air flow delivers the polyethylene sheets to the storage space and drying the sheets at the same time.

According to the preferred embodiment, the disclosed process may include the step of further 5shattering or fragmentizing the plastic laminates prior to the reacting step. The shattering steps can be achieved by any known devices in the art, though preferably a mechanical extruder or shredding machine is employed in the present invention. By preparing the plastic laminates into smaller fragments, the reacting surface of the plastic laminates with the acidic solution is greatly increased thus reducing the duration required for the stripping. ONonetheless, an additional washing step may be applied in another embodiment which the plastic laminates is cleaned or washed prior to the fragmentizing step. Cleaning of the plastic laminated to be recycled ensures less impurities being introduced into the acidic solution, while such impurities may decrease reactivity of the acidic solution and shorten the service life of the acidic solution in the process. Frequent replacement of the aged acidic solution5 with new batch of solution may be needed. Moreover, the washing step can be done concurrently with the fragmenting step by flushing water into the mechanical extruder to flush out the fragmentized plastic laminates.

Another embodiment of the present invention is a system capable of employing the above0mentioned process to recycle plastic laminates. The system of recycling plastic laminates in the present invention comprises a first tank for reacting plastic laminates with an acidic solution at a pH of 1 to 5; wherein the plastic laminates have layers made of any combination of polyethylene sheet, polyethylene terephthalate sheet, oriented polypropylene sheet and foil; an extruder receiving the reacted plastic laminates from the first tank and splitting the5plastic laminates to respective polyethylene sheet, polyethylene terephthalate sheet, oriented polypropylene and/or foil; a water passage filled with moving water flow washing the split polyethylene sheet, polyethylene terephthalate sheet, oriented polypropylene and/or foils derived from the extruder that the foil sinks to the bottom of the passage and being collected thereof; and a second tank equipped with soap bath or salt water for separating the washed0polyethylene sheet, polyethylene terephthalate sheet and/or oriented polypropylene sheets disposed therein, wherein the polyethylene sheets and the polyethylene terephthalate sheets or oriented polypropylene are collected at top and bottom of the soap bath or salt water respectively.

5As in the foregoing, the plastic laminates are preferably fragmentized before reacting with the acidic solution in the first tank. To fragmentize the plastic laminates, the disclosed system preferably locates an mechanical crusher, extruder or shredder at the upstream of the first tank. The extruder or shredder cuts the plastic laminates to much smaller pieces. This significantly increases surface area of the plastic laminates to be reacted with the acidic lOsolution, particularly the acidic solution can easily infiltrate into the plastic laminate by the edges of the fragmentized pieces to digest adhesive agent binding the individual sheets. Further the fragmentized pieces may be packed in a perforated sack and then transported to the first tank for digestion. The perforated sack renders the fragmentized pieces to be conveniently transported and collected upon digestion in the first tank. Nevertheless, the

15plastic laminates may be washed prior to fragmentation to clean dirt attached onto the plastic laminate.

The digestion of adhesive agent in the first tank by the acidic solution in the present invention is further accelerated via heating in one embodiment. Preferably, a heater or any other 0devices capable of heating the acidic solution or increasing the temperature of the acidic solution while reacting with plastic laminates is coupled to the first tank. Common gas heater or induction heating can be used for increasing the temperature of the acidic solution to a temperature of 65°C to 90°C. Increased temperature allows the acidic solution to dissolve the adhesive agent easier compared to normal room temperature, which requires longer reaction 5or digestion time to attain similar result. Apart from that, a stirrer may be equipped to the first tank as well to create turbulence within the mixture of acidic solution and the plastic laminates in the first tank to expedite the digestion process. The acidic solution used herein can be formic acid and/or acetic acid. One the reaction is completed in the first tank, the digested plastic laminates together with the perforated sack are collected from the first tank. The digested or reacted plastic laminates are then split into individual sheet preferably comprising polyethylene sheet, polyethylene terephthalate sheet, oriented polypropylene sheet and /or foil using the extruder. As early 5described, torque in the extruder creates friction in between the pressed plastic laminates splitting it into individual sheets for subsequent segregating process. Flowing water may be introduced into the extruder to drain the split individual sheets out from the extruder into the downstream water passage. The water passage in the disclosed system serves as a platform to separate foil, preferably aluminium foil, from the rest of the individual sheet. The foil with lOhighest density settles into the bottom of the water passage once entering the water passage, while the rest of the individual sheets are buoyed by the flowing water and collected at the end of the water passage way for further segregation in the second tank. Referring to the above description, the polyethylene terephthalate sheet and/or oriented polypropylene in fact has higher density than water that sheets of these material supposed to settle into the bottom

15of the water passage way once left enough long in water. However, with the aid of turbulence and water current in the water passage, the sheets of polyethylene terephthalate and/or oriented polypropylene are brought to the end of the water passage for collection before actual sinking.

20In the subsequent second tank located downstream of the water passage, the remaining individual sheets consisting of polyethylene sheet, the polyethylene terephthalate (PET) sheet and/or oriented polypropylene (OPP) sheet are treated with a soap bath or salt water stored within. The soap bath or salt water has density in between the of polyethylene sheet and the polyethylene terephthalate (PET) sheet/ oriented polypropylene (OPP) that the polyethylene 5 sheet with comparatively lower density float on the surface of the liquid medium. Yet, the polyethylene terephthalate sheet and/or oriented polypropylene sheet settle spontaneously to the bottom of the second tank. Turbulence is avoided in the second tank to accelerate the segregation or settling of the polyethylene terephthalate sheet and/or oriented polypropylene sheet. The separated polyethylene sheets at the surface of the soap bath or salt water are 0collected for recycling, preferably molten for reuse. Preferably, the salt used in the present invention are those neutral salts like sodium chloride, potassium chloride, or any other those commercially available. Nevertheless, other slightly acidic or alkaline salts are applicable in the present invention as well. More preferably, 5 sodium triphosphate is employed to achieve better separation.

The disclosed system may have an air blower incorporated at the downstream of the second tank to dry the collected polyethylene sheet. In more detailed, the air blower generates strong air current in a duct where the moist collected sheets, preferably polyethylene sheets, are lOplaced. The air flow carries the sheets to a storage space meanwhile water residues from second tank are vaporized in the process.

It is to be understood that the present invention may be embodied in other specific forms and is not limited to the sole embodiment described above. However modification and 15equivalents of the disclosed concepts such as those which readily occur to one skilled in the art are intended to be included within the scope of the claims which are appended thereto.