Reduction in polystyrene foams with dibasic esters

Details Reduction in polystyrene foams with dibasic esters Reduction in polystyrene foams with dibasic esters

2000-01-03

2004-06-01

Michl, Paul R. (Department: 1714)

Colloid systems and wetting agents; subcombinations thereof; pro

Compositions containing an agent for breaking ; processes of...

Continuous liquid phase colloid system and discontinuous gas...

Reexamination Certificate

active

06743828

ABSTRACT:

FIELD OF INVENTION
This invention provides chemical agents to reduce polystyrene foam plastics to a compact form using a dibasic ester based chemical agent in liquid form which reduces the polystyrene foam to a sludge like material that is safe to ship and greatly reduces its volume of waste.
BACKGROUND
Polystyrene foam has been used for some time as packing material, insulation material, structural materials and other various uses. The foam has exhibited a great number of useful qualities in a great number of fields. The foams usefulness is based partly on its cost effectiveness, its inherent insulating qualities and easy of forming a great variety of shapes. For instance the food handling industry has found foam packaging to be of great use in the packaging of food products for its consumers. In addition, the building industry has found a great number of uses for the foam. The chief concern for the various uses of the foam has been the amount of waste that is generated by the use of foam products.
Generally speaking, polystyrene foam has caused great concern because of its lack of biodegradability. The foam by its nature takes up a great deal of volume per weight, which has cause many to question its overall usefulness when compared to the possible detrimental environmental impact. The environmental impact includes the accelerated rate that landfill space is being used up at because the foam, in its useful form, takes a great deal of space per weight of waste. Moreover, the transportation of the foam waste is very inefficient due to the volume weight ratio. Typically, the waste material is transported from a restaurant facility to a waste area. This transportation usually involves motor vehicle transport. The vehicles can transport a much greater weight of refuse than can be place in the vehicle due to the large volume the foam takes up. Therefore, the transportation is very inefficient wherein it does not utilize the capacity of the shipping means.
Also, in the industry it has been very difficult to find an effective method of recycling the foam products. This is due in part to the shipping cost described above and the cost of the process of the actual recycling. There is a need for a foam volume reduction method to allow use of more normal plastic recycle and processing equipment. At the present extra compaction steps and very expensive and specialized equipment is required to recycle polystyrene.
One approach to the recycling is to use chemicals to reduce the foam. The basic problem is that the chemicals that are obvious are very toxic to the environment and they are often banned by environmental legislation or regulations. One chemical series, pinene and terpenes such as d-limonene can reduce the foam volume. This approach is interesting but it fails to be an effective method in some cases. Specifically, the cost of d-limonene is directly related to the crop levels of citrus products. When there is a problem with the production of citrus products due to bad growing conditions it directly effects the price to recycle foam products to the point where it may no longer be cost effective.
Moreover, prior approaches evidence an inconsistent activity in collapsing foams that has not previously been addressed in the industry. While heat activation of the terpines has removed this problem (U.S. Pat. No. 5,223,543) it adds to the overall cost of recycling and it involves a volatile environmentally compromising chemical. The chemicals used in this patent were all a problem to ship due to their flash point. They are very volatile and therefore extra precaution has to be used when shipping such products that ultimately does not make it cost effective. The process also was basically vapor phase, providing for possible emissions of vapors which were a Clean Air Act Problem. Thus there is a major need for a foam reduction process that uses low volatility agents.
Also, the use of volatile chemicals presents another problem to the recycling efforts. The chemicals used heretofore would suffer great loss in the recycling process due to evaporation. This would make the recycling materials vary hard to recover to be used again in the recycling process. As such it would add a great deal of cost to the recycling efforts. The evaporated chemicals would also increase the danger of an accident during the recycling process due to unacceptable flash points in the chemicals. This is especially true were the chemicals best performance was aided by the addition of heat to the process. Ultimately, the volatile chemicals and heat required would lead to conditions during the recycling process that would be very dangerous.
An ideal process would have little need for heat activation (contra to U.S. Pat. No. 5,223,543) and would further allow viscous and higher boiling point materials to be used. Ideally, these materials would not require longer residence times prior to recycling. A long time would delay the sequence of breaking down the foam products and shipping of the same. This increase in residence times would add to the overall cost of the recycling process. Also, the need to decrease residence time must be balanced with reduced heat activation in combination with higher boiling point materials whose combination would result in a hereto for unobtainable efficient and safe reactant. In addition, it would be most desirable to have the product or sludge of the foam collapsing reactions that is safely shippable. This is accomplished by the present invention as further described herein. It would also be advantageous to identify effective compounds that insulate the foam reducer market from the wide price variation of the orange crop related d-limonene market.
Also, it would be desirable to have a compound that is environmentally friendly. Part of the major problem with the past use of foam products is that they now occupy a great deal of space in our landfills. Therefore, there is a significant need for an agent that can be used at these landfills on foam, which has already been deposited into landfills. The only way to accomplish this is by the application of a foam reducing agent that has no detrimental side effects on the environment.
DESCRIPTION OF THE INVENTION
SUMMARY
This invention reveals a method to provide rapid destruction of the cells of polystyrene foams by use of a combination of specific chemicals of the class of aliphatic dibasic esters, either alone or with other foam reduction agents and surfactants that are active and which readily attack, with no or little heat activation, polystyrene foam and allows easy recycling. The easy recycling is due to reduced bulk and ease of storage of the collapsed polystyrene foam in sludge foam, ease of processing, and economical transportation prior to recycling. The process involves the exposure of said foams to liquid sprays of specific esters, which have a relatively high boiling point and may be easily and safely transported.
This invention solves the volume problem of polystyrene foam materials and allows the easy and inexpensive shipment of the foam materials after cost effective reduction in volume by use of liquid aliphatic dibasic esters. These materials such as dimethyl glutarate, dimethyl adipate and dimethyl succinate are all effective foam reduction agents. While they have activity individually, as mixtures the action is especially favorable. Moreover, with the addition of small amounts of heat to the process the overall effectiveness is increased while having little effect on the cost of recycling. Also, because of the reactants lower boiling points not much reactant is lost in the heating process. The lower boiling points and benign nature of the reactants makes the reactant process safer than know chemical reactants with highly boiling points.
The use of active chemicals assists in making foamed polystyrene materials easier to incinerate or reprocess. The product of this process and method is solvatable and can be made pumpable and can then be filtered and reprocessed or injected into the furnaces where the high fuel value of the material

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