Patent Description:
The present disclosure relates to densification of plastic material, preparing the material to be further recycled. This disclosure generally relates to transforming non-recyclable, lightweight, plastic waste into a recyclable form.

Plastic waste can present a long-lasting, difficult to store and transport pollutant. Plastic has many good structural qualities. It is lightweight and strong, as well as inexpensive to manufacture. As a result, lightweight plastics have become a part of everyday life for much of the world.

<CIT> describes a method of densifying polypropylene includes steps of reducing expanded polypropylene into relatively small particles and heating and compressing the particles to form densified polypropylene. The expanded polypropylene can be reduced to intermediate pieces prior to reduction to the small particles.

<CIT> describes a process and a device for processing plastic waste, such as packaging foil of polyvinylchloride, polyethylene, polypropylene etc. into blocks by compressing it in a container. The processing of the plastic waste is achieved by compressing with a punch at a temperature of <NUM> DEG -<NUM> DEG C. and a pressure of <NUM>-<NUM>/cm2 followed by cooling with air.

<CIT> describes a heated chamber with mobile platens for accepting thermoplastic material and compacting it into a shaped bale comprising compacted but unmodified material enclosed in a shaped skin of heat shrunk and chilled material. The chamber walls are heated and the walls and platens have passages for circulating coolant.

<CIT> describes a compress/melt waste processor includes a frame; a chamber housing having walls which define a chamber therein; a ram movably disposed in the chamber; a sensor which senses pressure applied by the ram; an actuator operatively connected to the ram to move the ram; a chamber hatch upon which the housing is mounted, the chamber housing walls, the ram and the chamber hatch defining a space therebetween; and a device for feeding contaminated plastic waste into the chamber.

The present disclosure involves systems, methods, and an apparatus for densifying plastic, such as plastic waste in the household. One embodiment relates to a plastic densifier as recited in claim <NUM>.

Implementations can optionally include one or more of the following features.

In some instances, the plastic densifier includes a loading mechanism affixed to the loading port, the loading mechanism including: a roller with a frictional surface that is configured to grab plastic and draw the plastic into the body, a comb fitted onto the roller and configured to remove plastic from the roller and deposit it through the loading port, and a roller motor configured to rotate the roller. The plastic densifier can also include a controller which controls operations of the plastic densifier and a lift motor which actuates the lift.

In some instances, the plastic densifier includes one or more temperature sensors and one or more current sensors which measure electrical current supplied to the lift motor. In some instances, the controller adjusts power supplied to the heating element to maintain a temperature sensed by the temperature sensor within a range of 100C to 180C. The controller can also be configured to apply current to the lift motor to a predetermined threshold. The predetermined threshold can be a current associated with a desired amount of compression of the plastic.

In some instances, a viewing window in the body is provided to permit inspection of the interior volume and of the plastic in the body.

In some instances, a cover is hingedly connected to the body.

Another embodiment relates to a method for densifying plastic as recited in claim <NUM>.

In some instances, during loading operations, the plastic is periodically compressed without applying heat.

In some instances, heat is applied to the plastic in response to a signal that the compression chamber is full.

In some instances, a loading mechanism that is automatically activated in response to a signal indicating the presence of plastic in the loading mechanism is used to load plastic into the compression chamber.

In some instances, the compression of the plastic, and applying heat to the plastic is repeated at least once. In some instances, applying compression and heat to the plastic is repeated in response to an indication that a predetermined compression ratio has not been achieved.

In some instances, compressing and applying heat to the plastic is repeated a predetermined number of times.

The details of these and other aspects and embodiments of the present disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description, drawings, and the claims.

In general, the disclosure relates to an apparatus, and method of use, for densifying plastic waste. Densified plastic waste is more compact, and solid than in its non-densified form. Lightweight plastic waste (e.g., used grocery bags, empty trash bags, food wrappers, etc.) can be difficult to store and transport, as well as process for recycling. This disclosure describes a convenient solution to allow users to compress or densify plastic waste in their home, making it readily recyclable, more conveniently stored, or easily transported for further processing.

The apparatus compresses the plastic waste, and then applies a limited amount of heat to "bake" the compressed plastic into a brick of plastic. Most plastic materials will begin to outgas volatile organic compounds (VOCs) when above a certain temperature. VOCs are generally toxic and undesirable in a residential setting, therefore the disclosed apparatus does not raise the temperature of the plastic so high as to cause widespread melting and therefore significant outgassing of the plastic. Instead the plastic is compressed, and then heated enough to cause it to retain its compressed shape, without melting or substantial outgassing.

<FIG> is an external isometric view of a plastic densifier <NUM>. The plastic densifier <NUM> can include a body <NUM>, which houses the majority of the components and can provide an aesthetically pleasing structure for the plastic densifier <NUM>. In some implementations, the body <NUM> is constructed of plastic, aluminum, steel, or any other suitable material. A cover <NUM> can be hingedly connected to the body, and can be opened to allow for removal of densified plastic or maintenance of the plastic densifier <NUM>. In some implementations, the cover <NUM> is slotted into the body <NUM> (e.g., via a tongue and groove system), or simply placed on top of the body <NUM>, the present disclosure is not limited thereto. The cover <NUM> will be described in further detail below with reference to <FIG>.

In some implementations, the plastic densifier <NUM> includes a loader <NUM> or loading mechanism. The loader <NUM> can be mounted to the cover <NUM> or the body <NUM>, and can assist in feeding light plastic waste into the body <NUM>. In some implementations, the loader <NUM> includes active powered components which are described in greater detail below and with reference to <FIG> and <FIG>.

<FIG> is a cutaway diagram showing an interior portion of plastic densifier <NUM> and some of the additional components. The body <NUM> includes an inner wall <NUM> which is constructed of an aluminum material. Aluminum is advantageous because it is a good heat conductor and heated plastic will not stick to it. In related examples, the inner wall <NUM> is steel or another suitable material which has good heat conductivity, sufficient structural integrity, and will not stick to the heated plastic.

Heating elements <NUM> can be positioned between the inner wall <NUM> and the outside wall of the body <NUM> to enclose a portion of the interior volume of the body <NUM>. The heating elements <NUM> can include resistive heating components, such as Nichrome <NUM>/<NUM> (<NUM>% nickel and <NUM>% chromium) strips, silicon carbide, or other element that can convert electrical power to heat. Heating elements <NUM> are positioned to apply heat to compressed plastic within the body <NUM> of the plastic densifier <NUM>. In some implementations, there are heating elements <NUM> in each wall (e.g., <NUM> walls) of the body <NUM>, as well as in the cover <NUM> and the lift <NUM>, to provide heat to the plastic from every direction.

Lift <NUM> is a mechanism configured to reduce the volume of storage space inside the body <NUM>, compressing plastic within. Lift <NUM> is shown in a scissor lift configuration, with a flat plate supported by a number of crosslinks. In some implementations, lift <NUM> can have an aluminum top surface with a heating element <NUM> configured to apply heat to the bottom of the plastic being compressed. Lift <NUM> can be actuated by any suitable means. In some implementations, a hydraulic or electric motor can rotate a screw drive which alters the distance between two links of the scissor lift at the bottom end. An example lift motor is illustrated and discussed in further detail below with respect to <FIG>.

Loader <NUM> in <FIG> is illustrated with a portion of its external housing removed, showing the rollers <NUM>, bevel gears <NUM>, and comb <NUM>. It should be noted that a roller <NUM> has been removed from the diagram for clarity. Rollers <NUM> can include a number of bumps or knobs which can grab light plastic to feed it into the body <NUM>. The rollers <NUM> can be rubber, plastic, metal, or a combination thereof which is suitable for providing traction to pull plastic into the plastic densifier <NUM>. As illustrated, the rollers <NUM> can have a generally spherical shape. In some implementations, they can be cylindrical or helical, among other shapes. Rollers <NUM> can be driven by a motor (not shown) which can rotate all the rollers <NUM> via bevel gears <NUM>. In the illustrated example there are three spherical rollers <NUM>, however more, or fewer, rollers <NUM> (e.g., six, or two) can be implemented without departing from the scope of this disclosure.

<FIG> depicts an example plastic densifier <NUM> in a rotated view, with some housing components transparent for clarity. The lift <NUM> is shown in an extended position, as it might be if it were compressing plastic. In the illustrated implementation, the lift <NUM> is actuated by a lift motor <NUM>, which can be an electric motor (e.g., brushless DC motor, stepper motor, AC motor, etc.) that drives a screw drive, which translates cross beam <NUM>, causing the scissor mechanism of the lift <NUM> to extend or retract based on the direction of rotation for the lift motor <NUM>.

Loader motor <NUM> is also illustrated in <FIG>, and can be a single electric motor, similar to, or different from lift motor <NUM>. Loader motor <NUM> in the illustrated implementation drives three rollers <NUM> via multiple sets of bevel gears <NUM>.

Viewing windows <NUM> can optionally be installed in the body <NUM> and can provide for a means for a user to visually verify the plastic within the plastic densifier <NUM>. The viewing windows <NUM> can be a Plexiglas material, glass, quartz, or other suitable transparent material (e.g., Pyrex®). As shown in the illustrated example, two viewing windows <NUM> can be installed, a long vertical window which shows the amount of plastic in the body <NUM> as well as the position of the lift <NUM>. In addition the vertical window, a lower, larger window can be provided to permit inspection of the densified plastic. In some implementations, the lower window <NUM> can be open-ended for easy removal of the densified plastic.

<FIG> illustrates the plastic densifier with its cover <NUM> in an open position. The open cover <NUM> can provide access to the storage volume <NUM>, which is within the body <NUM> of the plastic densifier <NUM>. Storage volume <NUM> can be the region where plastic is stored, compressed, and heated for densification. In some implementations, the open cover <NUM> permits easy removal of densified plastic from the storage volume <NUM>.

<FIG> show a side cutaway diagram of the plastic densifier <NUM>. Regions of <FIG> with a cross hash pattern indicate regions of the plastic densifier <NUM> with heating elements to apply heat to the plastic. In general, operations of the plastic densifier <NUM> can be broken into two phases: a loading phase and a densification phase.

During the loading phase, the lift <NUM> can be maintained near the bottom of the plastic densifier <NUM> as shown in <FIG>. Plastic to be densified is loaded in via the loader <NUM>. In some implementations, the loader includes one or more sensors and automatically activates when the presence of plastic to be loaded is detected. In general, the loading phase can be a long-term phase. For example, the plastic densifier <NUM> can be in the loading phase whenever it is not full, and can be slowly filled with plastic to be densified (e.g., grocery bags, wrappers, packing material, etc.) over a period of time (e.g., one week, on month, etc.). Upon the plastic densifier <NUM> being filled, it can then begin a densification phase. In some implementations, the plastic densifier <NUM> automatically detects when it is full and begins densification. In some implementations, densification is initiated based on user input (e.g., the user presses a "compress" or "densify" button).

During the densification phase, the lift <NUM> can rise, compressing the light plastic into a smaller volume that comprises the heated region <NUM>. In some implementations, a predetermined amount of pressure is applied by the lift <NUM>. For example, by measuring the current supplied to an electric motor actuating the lift <NUM>, it can be determined how much torque, and therefore, how much pressure is being exerted. In some implementations, additional sensors (e.g., a force sensor or pressure sensor) can be used to determine what height to raise the lift <NUM> to. Once the plastic is compressed, heating elements can apply heat to "bake" the plastic, causing it to harden and retain its compressed shape, without significant melting or outgassing of the plastic. The applied heat maintains the plastic in the range of 100C to 180C, and preferably below 120C. The upper bound of 180C prevents significant outgassing of the plastic, and the release of toxic VOCs. The lower bound of 100C ensures any moisture present in the plastic is vaporized and able to escape the densified plastic. In some implementations, once the plastic is within the desired temperature range, the lift is further actuated, applying additional pressure to further compress the plastic. This can be a cyclic, iterative process of applying heat and pressure. In some implementations, the process is carried out a predetermined number of times (e.g., <NUM> times, or <NUM> times etc.). In some implementations, the process can be carried out until a predetermined criteria is met (e.g., compression ratio or target volume). For example, the process can repeat until a compression ratio of less than <NUM>% is achieved. Following densification, the heating elements can be deenergized and the densified plastic allowed to return to ambient temperature. The lift <NUM> can either retract, to allow more plastic to be loaded on top of the brick of densified plastic or maintain position, to allow for easy removal of the brick. In some implementations, upon opening of the cover, or a removal port in the plastic densifier <NUM>, the lift <NUM> can raise the brick up and partially out of the densifier <NUM>, to make it readily removable.

<FIG> is a block diagram illustrating a controller <NUM> and some sensors and systems the controller can actuate. The plastic densifier <NUM> can be communicatively coupled with a controller <NUM>. While illustrated in <FIG> as separate components, the controller <NUM>, or a portion of the controller <NUM>, can be integrated into the plastic densifier <NUM>.

The controller <NUM> can receive inputs <NUM> from various sensors within the plastic densifier <NUM>. These inputs can include a temperature signal from one or more temperature sensors <NUM>. The temperature sensors <NUM> can be thermocouples, resistance temperature detectors (RTDs), thermistors, or other suitable temperature sensors. Temperature sensors <NUM> can be located within the plastic densifier, or near heating elements <NUM>, which can be similar to, or different from heating elements <NUM> as described with reference to <FIG>. Temperature sensors <NUM> can provide signals indicating the temperature of the heating elements <NUM>, the internal temperature of the plastic densifier <NUM>, a measured or estimated temperature of plastic within the plastic densifier <NUM> or any combination thereof. Controller <NUM> can further receive inputs <NUM> from one or more current sensors <NUM>, which can provide an indication of electrical current supplied to various components in the plastic densifier <NUM> (e.g., compressor motor <NUM>, loader motor <NUM>, heating elements <NUM>, etc.). One or more position sensors <NUM> can also provide inputs <NUM> to the controller. The position sensors <NUM> can be, for example, encoders connected to actuators associated with the loader or the lift (e.g., lift <NUM> and loader <NUM> as described with respect to <FIG>). In some implementations, position sensors <NUM> can be Hall Effect sensors, or an array of Hall Effect sensors, which sense magnetic fields and are able to determine the location of various components of the plastic densifier <NUM> (e.g., lift <NUM>, cover <NUM>, etc.).

One or more presence detector <NUM> can sense the presence of plastic in the plastic densifier <NUM>. Presence detector <NUM> can be, for example infrared (IR) rangefinders or ultrasonic sensors, which detect the presence of a solid object in a specific region. Presence detector <NUM> can determine whether a piece of plastic has entered the loader (e.g., loader <NUM>) and allow the controller <NUM> to actuate the loader motor <NUM> accordingly. Presence detectors <NUM> can additionally detect or sense an estimated volume of plastic in the plastic densifier (e.g., in the storage volume <NUM>).

The controller <NUM> can include a display <NUM> or provide signals to a display <NUM>, which can generally provide the user information on the current status and operations of the plastic densifier <NUM>. The display <NUM> can be an LCD display, OLED display, or any other suitable display. Display <NUM> can provide a graphical user interface to relay information to a user, as well as receive one or more inputs (e.g., via a touchscreen and soft keys, or buttons associated with the display) from the user.

The controller <NUM> can provide one or more outputs <NUM> to the system, including but not limited to, driving currents or control signals to the compressor motor <NUM>, which can be similar to, or different from the lift motor <NUM> as described with respect to <FIG>, the loader motor <NUM>, which can be similar to or different from the loader motor <NUM> as described with respect to <FIG>, the unloading door <NUM>, which can, in some implementations, be the cover <NUM> as described in <FIG>, a cover lock <NUM>, and one or more heating elements <NUM>. Outputs <NUM> can be electrical signals, digital or analog, or mechanical signals and outputs (e.g., rotation of a motor or gear).

In some implementations, where the unloading door <NUM> is automated, the controller <NUM> can automatically open the unloading door <NUM> upon completion of a densification phase, for easy removal of the densified plastic. In some implementations, when the heating elements <NUM> are active or when the compressor motor <NUM> is active, the cover lock <NUM> can be engaged, preventing inadvertent opening of the plastic densifier <NUM> by the user, when the plastic is hot and/or under pressure.

The preceding figures and accompanying description illustrate example processes and systems. However, the described system (or its software or other components) contemplates using, implementing, or executing any suitable technique for performing these and other tasks. It will be understood that these processes are for illustration purposes only and that the described or similar techniques may be performed at any appropriate time, including concurrently, individually, or in combination. In addition, many of the operations in these processes may take place simultaneously, concurrently, and/or in different orders than as shown. Moreover, the described systems and flows may use processes and/or components with or perform additional operations, fewer operations, and/or different operations, so long as the methods and systems remain appropriate.

Claim 1:
A method for densifying plastic, the method comprising:
loading plastic to be densified into a compression chamber on top of a lift or densified plastic on the lift, wherein the compression chamber defines an interior volume with an aluminum interior surface;
compressing the plastic by lifting the plastic using the lift; and
applying heat to the plastic to achieve a temperature in a range of 100C to 180C, wherein the compression and the heat bake the plastic into a brick of the densified plastic.