Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Reexamination Certificate
2001-04-17
2002-05-14
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
Reexamination Certificate
active
06388050
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a treating method for separating a flame retardant and a thermoplastic resin from a thermoplastic resin composition containing a flame retardant, which is used for a cabinet of a monitor in television, computer and the like, for example.
BACKGROUND ART
At present, for a cabinet of a monitor in television, computer and a cabinet for video recorder and the like, thermoplastic resins such as styrene resin, ABS (acrylonitrile-butadiene-styrene) resin and high impact polystyrene resin (copolymer or mixture of polybutadiene and polystyrene) with improved impact resistance are generally used. However, since there is a problem that the thermoplastic resin itself has high flammability, and from the viewpoint of prevention of the spread of the fire during a fire, a thermoplastic resin composition obtained by blending a thermoplastic resin and an agent which provides inflammability, such as a flame retardant and a flame retardant accelerator.
In particular, since a halogen type flame retardant has high flame retardant effect to various thermoplastic resins and the price thereof is low, it is widely used all over the world. Further, among the halogen type flame retardants, a bromide type flame retardant is superior in flame retardant effect to aromatic type resins such as styrene type resin and is used in great amounts for various cabinets and part materials for electric appliances. Therefore, when these electric appliances are wasted, great amounts of thermoplastic resin composition containing bromide type flame retardant are wasted.
In this regard, the resin wastes are treated generally by incineration or landfill and what is reused by heating and melting is only a part of the waste resins. From the viewpoint of preventing natural environment from being destroyed, the reuse by heating and melting is preferable. However, it is difficult to incinerate the resin compositions containing a flame retardant because of the given high inflammability and to treat them.
Further, with the increased consciousness for environmental problem, the harm of the halogenated organic compounds has been pointed out and the use of the halogenated organic compounds is being inhibited. At present, manufacturers using the flame retardant are investigating the changeover to a flame retardant containing no halogenated organic compound such as a phosphorous type compound. However, the inflammability which is given by the phosphorous type compound is lower compared to that given by the halogenated organic compound and the above-mentioned changeover is difficult to be achieved at present.
Further, in recent years, it has been desired to reuse resources, and the reuse of plastic materials has become a global problem. Therefore, it is an important problem to be solved to establish a method for treating and reusing the resin wastes. Particularly, as described above, the treatment and reuse of the resin composition containing a flame retardant is merely grappled with and becomes a great problem.
The present invention is suggested by considering such a situation, and an object thereof is to provide a treating method for separating a flame retardant and a thermoplastic resin from a thermoplastic composition containing a flame retardant.
DISCLOSURE OF INVENTION
The present invention provides a method for treating a thermoplastic resin composition containing a flame retardant comprising a dissolving or dispersing step (a) of bringing a thermoplastic resin composition containing a flame retardant into contact with a solvent to dissolve or disperse at least one portion of the flame retardant into the solvent.
It is effective that the above-mentioned treating method comprises a separating step (b) of separating a solution or a dispersion of the flame retardant after the step (a).
Further, it is effective to comprise a drying step (c) of drying the thermoplastic resin composition from which the flame retardant is separated after the step (b).
In the step (a), it is effective to maintain the temperature of the solvent at not lower than a heat distortion temperature of the thermoplastic resin composition when the thermoplastic resin composition containing a flame retardant is brought into contact with the solvent.
Further, it is effective that the flame retardant is a bromide type flame retardant.
Further, it is effective that thermoplastic resin is a styrene type resin.
Further, it is effective that the solvent is represented by the formula:
where R is hydrogen atom or methyl group, m is an integer of 0 to 4, x is an integer of 0 to 3.
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors have studied whole-heartedly to achieve the above-mentioned object and as a result have found a method for separating a flame retardant from a resin composition by bringing a thermoplastic resin composition containing a flame retardant into contact with a solvent to positively dissolve or disperse the flame retardant component.
Namely, the present invention relates to a method for treating a thermoplastic resin composition containing a flame retardant comprising a dissolving or dispersing step (a) of bringing a thermoplastic resin composition containing a flame retardant into contact with a solvent to dissolve or disperse at least one portion of the flame retardant into said solvent.
The thermoplastic resin composition in the present invention is a composition containing at least a thermoplastic resin and a flame retardant, which provides inflammability. As the other components, a flame retardant accelerator, a stabilizer, a colorant, a flowability reforming agent, release agent and the like may be contained insofar as the effect of the present invention is not decreased according to the uses of the resin composition.
As the flame retardant in the present invention, a flame retardant used in the field of the thermoplastic resin can be employed. For example, it can be exemplified by phenyl oxide type flame retardants such as decabromodiphenyl oxide, octabromodiphenyl oxide and tetrabromodiphenyl oxide, bisphenol A type flame retardants such as tetrabromobisphenol A (TBA), bromide type flame retardants such as hexabromocyclododecane, bis-tribromophenoxyethane, tribromophenol, ethylene bis-tetrabromophthalimide, TBA polycarbonate oligomer, polystyrene bromide and TBA epoxyoligomer, chloride type flame retardants such as chlorinated paraffin, perchlorocyclopentadecane and chlorendic acid, phosphorous type flame retardants, flame retardants containing a nitrogen compound and inorganic flame retardants.
The thermoplastic resin composition may contain one kind of the flame retardant and may contain a plural kinds of the flame retardants. Further, as the content of the flame retardant, there is no particular limitation insofar as the effect of the present invention is not decreased.
On the other hand, as the thermoplastic resin in the present invention, arbitrary one can be used. Among them, in particular, a styrene type thermoplastic resin (thermoplastic resin containing a styrene unit) is particularly effective for the reason that an amount and ratio of the styrene type thermoplastic resin used as an inflammable resin are great.
As this thermoplastic resin, there are, for example, polystyrene, poly-&agr;-methylstyrene, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer and styrene-maleic anhydride copolymer.
The thermoplastic resin composition of the present invention may contain one kind of the thermoplastic resins and may contain a plural kinds of thermoplastic resins.
Further, the molecular weight of the thermoplastic resin is not limited insofar as the effect of the present invention is not decreased and is preferably 3,000 to 1,000,000.
Among the bromide type flame retardants, a compound group called as Nondeca type exhibits good solubility to general-purpose solvents. On the other hand, decabromodiphenyloxide (commonly called Decabro) is insoluble to a solvent. According to the present invention, it is possible to separate the flame re
Kawakami Tetsuji
Nakajima Keizo
Onishi Hiroshi
Ueno Takayoshi
Boykin Terressa M.
McDermott & Will & Emery
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