NL2032488B1 - Method for processing waste parts of hard plastic foam - Google Patents

Abstract

Method for processing waste parts with a high content of hard plastic foam 5 In a method for processing hard plastic foam, in particular PU hard plastic foam, the plastic foam is first placed in an inert environment, where it is then reduced in size and pulverized. The inert environment is conditioned at a temperature of at least 30 °C and a relative humidity of less than 30%. During reduction, more than 95% of the propellant gases present are released from the plastic foam and these are captured and condensed into liquids in a cryogenic condenser. The resulting plastic foam powder with a particle size of 100-500 micrometers is then further reduced to a powder with a particle size of less than 50 micrometers. This powder is then mixed with a low-viscosity polyol blend and injected into a production installation for PU insulation.

Description

Method for processing waste parts of hard plastic foam

DESCRIPTION:

Field of the invention

The invention relates to a method for recycling waste parts of hard plastic foam, in particular hard plastic foam parts of 0 polyurethane (PU), into new raw materials.

State of the art

Recycling of products is increasingly encouraged by governments and agencies. To this end, a method of processing old materials into reusable raw materials must be developed and new applications and processing methods must be devised for these raw materials. EPS and

Summary of the Invention

The aim of the invention is to provide a method for sustainably recycling waste parts of hard plastic foam in the form of production waste, assembly waste or end-of-life waste into raw material or new product. To this end, the method according to the invention is characterized by: - reducing the hard plastic foam parts to particles with a size of a maximum of 500 um in an airtight closed space in which an atmosphere with an oxygen content of maximum 10% is present, - maintain a temperature of at least 30 °C in the atmosphere present in the enclosed space, and

- capturing gases released during size reduction by cryogenically condensing them.

It is critical for the installation to release and capture more than 95% of the propellants present in the plastic foam. To achieve this, the hard plastic foam parts must be sufficiently reduced in size and the atmosphere must be conditioned in the manner indicated. It is very important for the efficient release of propellants from the foams that the concentration in the atmosphere is kept as low as possible. Due to the presence of pentanes and harmful propellants in the hard plastic foam such as CFC-11, HCFC-141b and HFCs, the processing process takes place in a closed space with a nitrogen atmosphere with a low oxygen content.

Cryogenic condensation is a well-known technique, which mainly uses liquid nitrogen, to condense and freeze volatile organic compounds (VOCs) in an exhaust gas stream. Condensed and frozen VOC particles are removed to leave a clean gas stream for discharge to the atmosphere. This technology is particularly suitable for low flow waste streams containing solvents with a low boiling/freezing point. The Reclaimed

VOC particles can be reused.

In order to better release the propellant gases present in the plastic foam, the hard plastic foam parts are preferably reduced to particles with a size of maximum 250 µm. To efficiently reduce the hard plastic foam parts, this is preferably done in two steps.

In order to release the propellant gases present in the plastic foam even better, the atmosphere present in the enclosed space is preferably kept at a temperature of at least 40 °C during reduction.

To make the reduction and release of propellant gases even more efficient, a relative humidity of the atmosphere present in the enclosed space is preferably maintained during reduction of less than 30%.

An embodiment of the method according to the invention is characterized in that after reducing the hard plastic foam parts into particles with a size of a maximum of 500 µm, these particles are compressed into briquettes. Briquetting is preferably done without the use of adhesives so that the briquettes are suitable for chemical conversion.

A further embodiment of the method according to the invention is characterized in that after reducing the hard plastic foam parts to particles with a size of a maximum of 500 µm, these particles are further reduced into powder with a maximum particle size of 50 µm. Preferably, this powder is mixed with a polyol blend in a ratio of less than 65% powder and more than 35% polyol blend, after which the resulting suspension is used for the production of insulation material. Producing insulation material using recycled plastic powder using this method requires less fire retardant and less polyol blend than the known production method in which no recycled materials are used.

Brief description of the drawings

The invention will be explained in more detail below on the basis of exemplary embodiments of the method according to the White invention shown in the drawings. This shows:

Figure 1 shows a schematic representation of a first embodiment of the method according to the invention;

Figure 2 shows a schematic representation of a second embodiment of the method according to the invention; and

Figure 3 shows a schematic representation of a manufacturing method for manufacturing insulation material.

Detailed description of the drawings

Figure 1 shows schematically a first embodiment of the method according to the invention. Waste parts 1 of hard plastic foam, for example PU hard plastic foam parts, in the form of production waste, assembly waste or end-of-life waste, are reduced in a shredder, process step 3, to particles with a size of up to 500 um.

Due to the presence of pentanes and harmful propellants such as

CFC-11, HCFC-141b and HFCs in rigid plastic foam, the processing process is carried out in a closed space in which a mainly nitrogen atmosphere with less than 10% oxygen is present. The conditions of the atmosphere largely determine the evaporation of propellant gases. Released propellants and dust are extracted from the shredder. It is critical for the installation to release and capture more than 95% of the propellants present in the plastic foam. To this end, the atmosphere is conditioned as follows: - the relative humidity is kept below 30%, process A, with the aid of cooling towers which force condensation in a partial flow of the atmosphere by cooling; - the temperature is kept above 30 °C, process B, using a heat exchanger that monitors the balance between the cooling of cooling towers, natural heat loss and the increase in temperature due to the processing of hard plastic foam: and - released propellant is cryogenically condensed, process C, to keep the concentration of propellant in the atmosphere as low as possible so that propellant is released from the hard plastic foam as efficiently as possible.

The foam powder 5 can then be further processed in two ways: 1. Compression into briquettes of 6-10 cm in diameter, without the use of adhesives, process step 7. This achieves a weight of 250-450 kg/m3. Briquettes are suitable for transport and suitable for chemical conversion due to their high purity. 2. Further reduction of the powder to a diameter of less than 50 micrometers, process step 9. Due to the reduction of the powder to particles smaller than 50 micrometers, the powder is extremely suitable for mixing in liquids and mechanical processing.

Figure 2 shows schematically a second embodiment of the method according to the invention. This differs from the first embodiment in that the hard plastic foam parts are reduced in size in two steps. In the first shredder 3, the plastic foam parts 1 are coarsely reduced into particles 11 and in a second shredder 13 the particles 11 are then reduced into powder 5 with a particle size of 100-500 micrometers. The plastic foam is pulverized in such a way that all cells in the foam break open, allowing the remnants of propellant gases to escape.

To collect these propellant gases, the second shredder is also placed in an airtight closed space in which a nitrogen atmosphere with less than 10% oxygen is present. The temperature and humidity are also kept at the same values as in the first shredder. After the second shredder, more than 98% 5 of the cells in the hard plastic foam are broken. More than 95% of the propellant gases have been released from the hard plastic foam. These propellants are released from the cryogenic condenser as liquids, which are transferred to mobile pressure vessels for further processing.

Figure 3 shows a schematic representation of a manufacturing method for producing PU insulation material from powder. The powder 21 with particle size smaller than 50 micrometers is mixed with polyol blend 23 in a ratio of less than 65% PU powder and more than 35% polyol blend. The resulting suspension 25 is kept agitated 27 and heated 29 to >40°C.

The suspension 25 is then sent to a foam head 33 with a pump 31 at high pressure to produce PU insulation. The resulting PU insulation with recycled plastic powder requires less flame retardant and less polyol blend to be produced.

Although the invention has been explained in the foregoing with reference to the drawings, it should be noted that the invention is by no means limited to the embodiments shown in the drawings. The invention also extends to all embodiments deviating from the embodiments shown in the drawings within the framework defined by the claims.

Claims (9)

CONCLUSIONS: 1. Method for processing waste parts of hard plastic foam, in particular PU hard plastic foam parts, comprising: - reducing the hard plastic foam parts to particles with a size of maximum 500 um in an airtight closed space in which an atmosphere is present with an oxygen content of maximum 10%, - maintaining the atmosphere in the enclosed space at a temperature of at least 30 °C during comminution, and - capturing gases released during comminution by cryogenically condensing them. 2. Method according to claim 1, characterized in that the hard plastic foam parts are reduced to particles with a size of maximum 250 um. Method according to claim 1 or 2, characterized in that the reduction of the hard plastic foam parts takes place in two steps. 4. Method according to claim 1, 2 or 3, characterized in that during comminution the atmosphere present in the closed space is kept at a temperature of at least 40 °C. 5. A method according to any one of the preceding claims, characterized in that a relative humidity of the atmosphere present in the closed space of less than 30% is maintained during comminution. 6. A method according to any one of the preceding claims, characterized in that after reducing the hard plastic foam parts into particles with a size of a maximum of 500 µm, these particles are compressed into briquettes. 7. Method according to claim 6, characterized in that the briquetting takes place without using adhesives so that the briquettes are suitable for chemical conversion. A method according to any one of the preceding claims, characterized in that after reducing the hard plastic foam parts to particles with a size of a maximum of 500 um, these particles are further reduced into powder with a maximum particle size of 50 um. Method according to claim 8, characterized in that the powder with maximum particle size of 50 µm is mixed with a polyol blend in a ratio of less than 65% powder and more than 35% polyol blend, after which the resulting suspension is used for production of insulating material.