Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Patent
1996-06-17
1999-07-13
Teskin, Fred
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
528491, 528493, 528494, 528495, 528496, 528498, 528499, 521 47, C08J 1108
Patent
active
059228350
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method of compacting expanded polystyrene (EPS) as well as the processing of the thus obtained compacted mass.
BACKGROUND OF THE INVENTION
EPS is originated from the addition of blowing agents to polystyrene (PS) in order to obtain the PS as a foamed structure: a matrix comprised of fixed or flexible, coherent structural elements of PS that constitute spatial open or closed cells or cavities in which air and/or blowing agents are contained, whether free or entrapped.
EPS has found widespread use in insulation of heat; absorbtion of noise, vibration and shocks; light-weight-structured material in sandwich panels and transport packages; foamed packaging chips; etc.
The voluminous nature of EPS, especially in the state of waste, creates a problem in that high logistic costs per ton polymer are involved in handling and transport. A truckload of EPS, having a mean density of 25 kg/m.sup.3, only contains 800 to 1000 kg PS.
A reduction of volume, for instance, can be obtained by mechanical means like pressing or treatment between compactor rolls. This type of equipment, especially the roll compactor, is precious and takes relative large amounts of energy to do the job. Especially for the elastic types of foam, mechanical systems perform less efficiently. Furthermore it is difficult to keep polluting blowing agents like CFK's, present in the older types of EPS, from entering the environment during the compacting process.
Methods, among others, are known from the literature in which polymers are brought into contact with solvents for those polymers. These methods lead to more or less homogeneous solutions of either low or high viscosity, mainly applied as adhesives. DE-C1 37 41 777 is related to waste PS that, in contact with solvents, leads to PS solutions with adhesive properties. DE-A1 31 13 125 is related to EPS that, in contact with "stain remover", leads to a solution with adhesive properties. DE-A1 23 03 754 is related to EPS that, in contact with chlorinated hydrocarbons, in particular highly chlorinated hydrocarbons and at higher temperatures, leads to sticky masses with adhesive properties.
A need remains to convert waste EPS in an effective way in a form that, on the one hand, leads to economic advantage by lowering logistic costs related to collecting, handling, storage and transport and, on the other hand, offers the opportunity for reprocessing, whether physically to PS, or chemically to monomer styrene and other raw materials, in that a certain amount of contamination and incompatibility due to the presence of sticker labels, printing ink, other polymers, adhering sand, organic matter, etc. is not objectionable.
SUMMARY OF THE INVENTION
It is discovered that the problem can be solved by bringing the EPS in contact with a liquid composed of at least one component with solving power in respect of polystyrene and at least one component without solving power in respect of polystyrene.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a method of compacting EPS by bringing the EPS in contact with a liquid composed of at least one component with solving power in respect of polystyrene and at least one component without solving power in respect of polystyrene. The following definitions apply to the invention:
The phrase "component with solving power in respect of a polymer" means that a component has solving power if, in the liquid state, it weakens the bonds between the molecules of a submerged polymer in such a way that these molecules lose their mutual coherence and as a final consequence a one-phase system arises with fluid or semi-fluid properties, in which the molecules are, more or less, homogeneously distributed over the entire system volume. Things to be considered include the temperature range in which the method is applied. In the examples "a component with solving power in respect of polystyrene" is simply referred to as "a solver". The solver of polystyrene may be (i) an aromatic hydrocarbon constituted of 1, 2, 3 or 4 ben
REFERENCES:
Mar. 4, 1978. Jul. 28, 1978.
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