Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L91/00—Compositions of oils, fats or waxes; Compositions of derivatives thereof
  • C08L91/06—Waxes
• • 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
  • C08F255/00—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00
  • C08F255/02—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00 on to polymers of olefins having two or three carbon atoms
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/06—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond

Definitions

• This disclosure is related to the modification of the rheological properties of polyethylene or polyethylene copolymers.
• Polyolefins are commonly modified by reactive extrusion. The modification is often desirable in order to facilitate the blending of the generally incompatible polyolefins with other polymers.
• Reactive extrusion functionalizes the polyolefins and thus is a method typically employed to overcome their incompatibility issue with other polymers.
• Most polyolefins, such as polypropylene, upon grafting have desirable functional rheological properties that permit secondary manipulation or formation of a desired end product.
• the rheological properties of polyethylene or polyethylene copolymers generally change to a less desirable state.
• One characteristic of grafted polyethylene polymers and copolymers is that their melt flow index decreases upon grafting when compared to the polymer in the ungrafted state.
• grafted polyethylene polymers or polyethylene copolymers that have enhanced rheological properties.
• One particular convention for measuring rheological properties of a polymeric melt is the melt flow index, as specified under ASTM D1238.
• the grafted polyethylene polymers or polyethylene copolymers, produced in accordance with this disclosure exhibit melt flow indices (“MFI”) of at least 50% greater when compared to the functionalized polyethylene copolymer produced in the absence of an oligomeric or polymeric wax.
• rheological properties include melt viscosity, melt transition temperature (T m ), glass transition temperature (T g ), and the storage modulus (G′) and/or loss modulus (G′′) at a specified temperature or shear rate.
• the grafted polyethylene polymers and copolymers are suitable for various applications such as compatibilizers, coupling agents, viscosity modifiers, surface modifiers, lubricants, impact modifiers and tie-layers.
• the grafted polyethylene polymers have specific application as coupling agents for glass, mineral or natural fiber filled polyolefins. By controlling or tailoring the rheology of the grafted polyethylene, it is possible to improve the effectiveness and performance in such composite systems. In one embodiment, it is desirable to increase the melt flow index and subsequent flow properties of the grafted polyethylene polymer to improve the likelihood of successful interfacial bonding during melt processing of the composite system.
• Enhanced or improved rheological properties of polyethylene polymers or copolymers is contemplated by a melt processable polymeric composite derived from the combination of a polyethylene or polyethylene copolymer, an oligomeric or polymeric wax, a functionalized agent, and a free radical initiator. Melt processing the polyolefin or polyolefin copolymer with an oligomeric or polymeric wax, maleic anhydride, and a functionalized agent forms a grafted polyethlyene polymer or polyethylene copolymer with desirable and improved rheological properties.
• Polyethylene or polyethylene copolymers function as the host polymer and are a component of the melt processable composition subjected to the reactive extrusion process along with the other components.
• a wide variety of polyethylene polymers and copolymers conventionally available and suitable for melt processing are useful.
• the polyethylene or polyethylene copolymers may comprise from about 20% to about 90% by weight of the entire composition.
• a non-limiting example of a commercially available polymer includes Dowlex IP40, high density polyethylene from Dow Chemical Corporation, Midland, Mich. Other conventional low density and linear low density polyethylene polymers or copolymers are suitable as well.
• the polyethylene or polyethylene copolymers may comprise from about 20% to about 90% by weight of the entire composition.
• Oligomeric or polymeric waxes are generally those low molecular weight waxes that have a weight average molecular weight of less than 50,000 g/mol, and are compatible with the polyethylene matrix during melt processing.
• the low molecular weight wax has a weight average molecular weight of less than 20,000 g/mol. In most preferred embodiments, the low molecular weight wax has a weight average molecular weight of less than 10,000 g/mol.
• Non-limiting examples of oligomeric and polymeric waxes include, polyethylene waxes, polypropylene waxes, triglyceride waxes, diglyceride waxes, monoglyceride waxes, fatty acid waxes, fatty amide waxes, and metal stearates.
• the amount of oligomeric or polymeric wax present in the melt processable composition is dependent upon several variables, such as for example, the polyethylene polymer or copolymer, the type of functionalizing agent, the type of melt processing equipment, the processing conditions, and others. Those of ordinary skill in the art with knowledge of this disclosure are capable of selecting an appropriate amount of oligomeric or polymeric wax to achieve the desired result. In certain embodiments, the oligomeric or polymeric wax is used at 0.01 to 80 wt % by weight of the melt processable composition.
• the oligomeric or polymeric wax is used at 1.0 to 50 wt % by weight of the melt processable composition.
• Functionalizing agents enable the incorporation of a reactive moiety onto the backbone of the polyethylene polymers and polyethylene copolymers.
• the resulting functionalized polyethylene polymer or copolymer can have utility as an interfacial modifier (e.g., compatibilizer, coupling agent, surface modifier, tie-layer).
• the grafting process that takes place in the melt is accomplished by free radical grafting of an unsaturated polar monomer or functionalizing agent onto the polyethylene polymer or copolymer.
• functionalized agents include ethylenically unsaturated monomers having a reactive group. Examples include functionalized acrylates, methacrylates, stryenics, dienes and olefins.
• the reactive group may be any electrophilic or nucleophilic reactive moiety.
• Non-limiting examples of reactive groups include: amines, amides, esters, carboxylic acids, carboxylic acid halides, anhydrides, imides, alcohols, isocyanates, oxazolines, epoxides and silanes.
• the functionalizing agents may be included in the melt processable composition in amounts ranging from about 0.1% to about 10% by weight. In certain embodiments, the functionalized agent may be included at about 0.5% to about 5% by weight.
• a free radical initiator is a species that, when melt processed, forms reactive free radical moieties that influence the grafting process in the extruder.
• Free radical initiators useful in the grafting process include organic peroxides and diazocompounds.
• Non-limiting examples of specific free radical initiators include: benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide and azoisobutrylnitrile.
• the free radical initiator may be included in the melt processable composition at amounts less than 1% by weight.
• the melt processable composition can be prepared by any of a variety of ways.
• the polyethylene polymers and polyethylene copolymers, the oligomeric or polymeric wax, and the functionalized agent can be combined together by any of the blending means usually employed in the plastics industry.
• melt-processing typically is performed at a temperature from 120° to 300° C., although optimum operating temperatures are selected depending upon the melting point, melt viscosity, and thermal stability of the composition.
• Different types of melt processing equipment such as extruders, may be used to process the melt processable compositions of this invention.
• an extruder is utilized to enable a reactive extrusion of the components.
• Those of ordinary skill in the art in polymer processing are able to select appropriate operating conditions based upon the specific materials utilized for forming the grafted polyethylene or polyethylene copolymer.
• the melt processing and reactive extrusion is performed in a twin screw extruder.
• the reactive extrusion is performed in a co-rotating, segmented twin screw extruder.
• it is preferable that the length:diameter of the twin screw extruder is at least 32:1.
• the length:diameter of the twin screw extruder is at least 40:1.
• the resulting grafted polyethylene or polyethylene copolymers possess desirable rheological characteristics.
• grafted polyethylene polymers and polyethylene copolymers made in accordance with this disclosure can exhibit enhanced or improved melt flow indices as measured in accordance with ASTM D1238.
• the grafted polyolefin or polyethylene copolymer has a melt flow index value according to ASTM D1238 of at least 50% greater value than the melt flow index of a grafted polyethylene or polyethylene copolymer produced in the absence of the oligomeric or polymeric wax.
• the melt flow index is at least 100% greater and may be at least 200% greater.
• rheological properties such as flexural strength, flexural modulus, tensile strength, tensile modulus, tensile elongation, moisture resistance and impact properties may be enhanced.
• the grafted polyethylene polymers and copolymers are suitable for various applications such as compatibilizers, coupling agents, viscosity modifiers, surface modifiers, lubricants, impact modifiers and tie-layers.
• Table 1 gives the formulations for comparative example CE1 and Examples 1-2.
• Table 2 gives the properties for comparative example CE1 and Examples 1-2.

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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)
• Oil, Petroleum & Natural Gas (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Graft Or Block Polymers (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

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• 2014
  • 2014-03-13 EP EP14774108.6A patent/EP2970545A4/fr not_active Withdrawn
  • 2014-03-13 WO PCT/US2014/025513 patent/WO2014159952A1/fr active Application Filing
  • 2014-03-13 US US14/764,876 patent/US20150376409A1/en not_active Abandoned
  • 2014-03-13 MX MX2015010664A patent/MX2015010664A/es unknown
  • 2014-03-13 CA CA2900301A patent/CA2900301A1/fr not_active Abandoned
• 2017
  • 2017-08-16 US US15/678,913 patent/US10745562B2/en active Active

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