Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
  • C08K5/098—Metal salts of carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/50—Partial depolymerisation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0033—Additives activating the degradation of the macromolecular compound
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/07—Aldehydes; Ketones

Definitions

• This invention relates generally to plastic compositions, and more particularly, to a ther o- plastic composition which comprises a thermoplastic polymer such as polyetheylene or ethylene copolymers, polypropylene, polystyrene or polyurethane which is photodegradable when exposed to sunlight and/or ultraviolet light.
• a thermoplastic polymer such as polyetheylene or ethylene copolymers, polypropylene, polystyrene or polyurethane which is photodegradable when exposed to sunlight and/or ultraviolet light.
• Plastic waste is normally disposed of by recycling, incineration or burying in a landfill.
• Some materials are improperly dis ⁇ posed of and become litter.
• This litter is both esthetically objectionable and poses a threat to wildlife through possible entrapment and/or inges- tion. Therefore, there is a need for a material which will degrade harmlessly when exposed to sun ⁇ light, ultraviolet light or heat.
• additive compositions which may be incorporated into thermoplastic materials to enhance degradation of the plastic. For example, U.S.
• patent 4,931,488 discloses a thermoplastic polymer composition to which has been added a bio- logically degradable substance such as starch, an iron compound, an oxidizable substance selected from fatty acids and/or fatty acid esters and a transi ⁇ tion metal.
• a bio- logically degradable substance such as starch, an iron compound, an oxidizable substance selected from fatty acids and/or fatty acid esters and a transi ⁇ tion metal.
• This composition demonstrates biodegradation and photodegradation capability when exposed to heat, ultraviolet light, sunlight, or under compositing conditions. But, many states today require only that a plastic composition only be photodegradable. In this connection, the use of a composition such as that disclosed in patent 4,931,488 may not be advantageous.
• the starch com- ponent in the composition becomes unnecessary when biodegradation is not required, and the starch may cause the product to become sensitive to moisture pickup during the production process and does little to enhance photodegradation. Therefore, a plastic composition which possesses the desired properties of thermoplastic materials, yet readily degrades when exposed to sun ⁇ light and/or ultraviolet light, is highly desirable.
• thermoplastic materials it is the primary object of the present invention to provide a plastic composition which readily degrades when exposed to sunlight and/or ultraviolet light and to provide such a plas ⁇ tic composition for films, sheets or other moldings, which possesses the desired properties of known thermoplastic materials.
• thermoplastic composition which is degradable under the action of sunlight and/or ultraviolet light and heat.
• the thermoplastic com ⁇ position comprises a thermoplastic polymer, a first transition metal compound which may be a complex, a second transition metal compound and an aromatic ketone.
• the thermoplastic polymer preferably comprises an olefin such as polyethylene, ethylene copolymers, polypropylene, polystyrene or polyurethane.
• the first transition metal comprises an iron compound such as ferric hydroxy stearate, which is soluble in the composition and acts as an initiator which promotes further degradation.
• the second transition metal comprises a copper compound which acts as a catalyst with the iron compound to enhance degradation.
• the aromatic ketone includes benzophenone. It has been found that by using the composition of the present invention in a thermo ⁇ plastic material that a significant synergistic deg ⁇ radation effect occurs on the plastic when exposed to sunlight and/or ultraviolet light.
• Fig. 1 is a graph illustrating loss of elonga ⁇ tion at break as a function of time in a plastic film product including the composition of the pre ⁇ - ent invention.
• thermoplastic composition in accordance with the present invention facilitates biodegradation of thermoplastic materials under the action of sunlight and/or ultraviolet light and heat. That is, the chemicals in the composition in the presence of the sunlight or ultraviolet light and heat react to form free radicals which break the bonds cf the thermoplastic polymer resulting in a reduction of molecular weight and loss of physical properties. Thereafter, the thermoplastic material becomes weak and brittle which results in a material that is easily disintegrated by exposure to the ele ⁇ ments.
• thermoplastic composition of the present invention comprises as one component thereof a ther ⁇ moplastic base of any known thermoplastic polymer and preferably polymers of olefins such as polyethylene, ethylene copolymers, polypoypylene, polystyrene or polyurethane.
• Polyethylene as used herein, comprises any type of polyethylene, such as LDPE, LLDPE, LMDPE, MDPE, HDPE, ULDPE, etc.
• Exam- pies of suitable ethylene copolymers include EVA,
• composition of the present invention may be formed in any of the following manners.
• the compo ⁇ sition may be added directly at the final production stage by the manufacturer, formed in a concentrate and supplied to the manufacturer to be added to the base resin or formed with the base resin and supplied to the manufacturer ready for use.
• the first transition metal component preferably comprises an iron compound generally having the for ⁇ mula X-Fe, where X represents one or more ligands.
• the compound may additionally be coupled to a fur ⁇ ther ligand Y.
• Fe may designate iron in any known valancy.
• the ligand X may be an inorganic or organic acid radical or likewise another ligand bonded in a complex.
• suitable ligands X include OH-, C1-, Br-, I-, oxalate-, H-citrate-, NO- , N-.- EDTA or a carbonyl, nitrosyl or porphyrin radical.
• Suitable ligands Y include carboxylic acid ions of aromatic or aliphatic monocarboxylic acid or of dicarboxylic acids, the aliphatic carboxylic acid preferably having 10 to 20 carbon atoms.
• Ligand Y serves in general to increase the solubility of the compound X-Fe in the polymer.
• the iron compound more preferably is comprised of iron stearate pres ⁇ ent in the final concentration of the present inven ⁇ tion in an amount from about 0.01 weight percent to about 0.5 weight percent, and more preferably in an amount from about 0.1 weight percent to about 0.3 weight percent. It is understood that the ranges listed herein are for purposes of illustration.
• the amount listed for the upper limits is based on eco ⁇ nomics, and therefore, the components may be present in the concentration in amounts greater than those listed. Although, a saturation limit is reached at which further addition does not provide greater effectiveness. The minimum value listed provides minimum measurable improvements in photodegradation.
• the second transition metal compound of the thermoplastic composition of the present invention acts as a catalyst with the first transition com ⁇ pound to enhance degradation of the thermoplastic material.
• the compound may comprise a complex having the general formula Z'-Me, wherein Me desig ⁇ nates a transition metal other than iron if iron is the first transition metal and Z ' designates one or more ligands.
• examples of ligands include OH-, C1-, Br-, I-, oxalate-, H-citrate-, NO ⁇ 2 , N,-, EDTA, as well as carboxylic acid ions of aromatic or aliphatic monocarboxylic or dicarboxylic acids, the aliphatic carboxylic acid preferably having 10 to 20 carbon atoms.
• the preferred transition metals comprising Me are the transition metals of the first transition metal row in the periodic table, and more preferably copper and vanadium.
• the most preferred second transition metal compound is copper stearate present in the final concentrate of the present invention in an amount from about 0.005 weight per ⁇ cent to about 0.1 weight percent, and more pre ⁇ ferably cupric stearate in an amount from about 0.01 weight percent to about 0.06 weight percent.
• aromatic ketone component of the composi- tion of the present invention has been found to have a synergistic effect that speeds up the photodegradation of the thermoplastic. This is an unobvious finding since aromatic ketones generally are ultraviolet stabilizers.
• aromatic ketones generally are ultraviolet stabilizers.
• aro ⁇ matic ketones include benzophenone, anthraquinone, anthrone or derivatives such as acetylbenzophenone or 4-octyl benzophenone.
• the more preferred aromatic ketone is benzophenone which is present in the concentration in an amount of from about 0.01 weight percent to about 0.7 weight percent and more preferably in an amount from about about 0.02 weight percent to about 0.15 weight percent.
• Utilizing the composition of the present inven ⁇ tion is further advantageous in that the degradation can be controlled depending on the field of applica ⁇ tion by varying the concentration of the individual components, without the plastic material suffering a deterioration in its properties under normal use conditions.
• Particular fields of application of the composition of the present invention include packaging materials, films for garbage bags for co - postable wastes, agricultural films, and in particu- lar those materials which may become litter such as disposable packaging.
• the present invention makes it possible to manufacture products which do not pollute the environment and which can be degraded without additional energy consumption and without releasing harmful substances.
• thermoplastic composition in a concentrate form in accordance with the present invention and its processing to give sheets, films, plates or other shapes is carried out by any conven- tional method.
• the polyethylene may be combined with the appropriate amounts of iron stearate, copper stearate and benxophenone in a twin screw compounding extruder or equivalent and extruded and pelletized into a concentrate or mas- terbatch.
• Extruded film, blow molded parts or injection moulded parts are made by combining this concentrate with polyethylene or other base resins in a film extruder or injection molding extruder, which is normally of the single screw type.
• the chemicals could be added directly at the final production stage in the single screw extruder, this however is not very practical.
• thermoplastic base i.e., polyethylene
• the half life of biological degradation of polyethylene was extrapolated to be at least 100 years.
• sun ⁇ light or heat free radicals such as, for example OH* are formed due to the presence of iron ions, and these can react with the polymers forming other free radicals.
• These free polymer radicals are extremely reactive and can, inter alia, react further with oxygen, other chains, iron ions, and the like. Polymer chains are thus split and small chains with or without oxygen-containing groups, such as alco- hols, ketones, etc. are formed.
• iron ions act both as an initiator and as a reaction promoter since iron-(in) hydroxide com ⁇ plexes are highly reactive. This can be illustrated the by the following equation:
• Cu+ ions are reoxidized very fast to Cu 2+ ions by free radicals as follows:
• this phase takes in general from about 10 to 60 days.
• thermoplastic composition of the present invention formed in a concentrate wherein the compositional ranges of the various components are by weight percent of the total concentrate.
• thermoplastic composition of the present invention formed in a concentrate wherein the compositional ranges of the various components are by weight percent of the total concentrate.
• a From about 0.1 percent to about 0.3 per ⁇ cent iron stearate; b. From about 0.01 percent to about 0.06 per ⁇ cent copper stearate; c. From about .02 percent to about 0.15 per ⁇ cent benxophenone; d. Balance thermoplastic polymer.
• thermoplastic composition of the present invention formed in a concentrate wherein the compositional ranges of the various components are by weight percent of the total concentrate.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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• 1991
  • 1991-12-20 EP EP92903541A patent/EP0563291A1/en not_active Withdrawn
  • 1991-12-20 WO PCT/US1991/009731 patent/WO1992011298A1/en not_active Application Discontinuation
  • 1991-12-20 KR KR1019930701906A patent/KR930703370A/ko not_active Application Discontinuation
  • 1991-12-20 CA CA002098911A patent/CA2098911A1/en not_active Abandoned
  • 1991-12-20 JP JP50375992A patent/JP3184886B2/ja not_active Expired - Fee Related

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