Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
2000-05-03
2002-11-05
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
C428S476900, C428S517000, C428S522000, C525S191000, C525S193000, C525S194000
Reexamination Certificate
active
06475633
ABSTRACT:
The present invention relates to a coextrusion binder based on a mixture of cografted polyolefins.
The invention relates more particularly to a mixture, which is useful as a coextrusion binder, of at least (A) one polyethylene or one ethylene copolymer and of at least (B) chosen from (B1) propylene or a propylene copolymer, (B2) poly(1-butene) homo- or copolymer and (B3) polystyrene homo- or copolymer, the mixture of (A) and (B) being grafted with a functional monomer, this grafted mixture itself optionally being diluted in at least one polyolefin (C) or in at least one polymer of elastomeric nature (D) or in a mixture of (C) and (D).
These coextrusion binders are useful, for example, for manufacturing multilayer packaging materials. Mention may be made of materials comprising a polyamide (PA) film and a polyethylene (PE) film, it being possible for the polyethylene film to be laminated on the polyamide film or coextruded with the polyamide. The coextrusion binder is placed between the polyethylene and the polyamide for good adhesion of the PA and of the PE. These multilayer materials may be PE/binder/EVOH three-layer structures in which EVOH denotes a copolymer of ethylene and vinyl alcohol or an ethylene/vinyl acetate (EVA) copolymer which is partly or totally saponified, or PE/binder/EVOH/binder/PE five-layer structures.
The prior art EP 35,392 describes polyethylenes or ethylene copolymers containing at least 85 mol % of ethylene grafted with maleic anhydride. These grafted polyethylenes may then be diluted in polyethylenes or ethylene copolymers containing at least 50 mol % of ethylene, on condition that the mixture contains at least 80 mol % of ethylene. These products are coextrusion binders. The prior art EP 188,926 describes polypropylenes grafted with maleic anhydride, which are useful as coextrusion binders.
The radical grafting of functional monomers onto polyolefins is carried out either in the molten state or in solution, using radical initiators such as peroxides, or in the solid state by irradiation. Under the action of the radicals, side reactions take place at the same time as the grafting reaction. They lead to an increase in the molecular mass when the polymer to be grafted is polyethylene, or to a decrease therein when it is polypropylene. If the amount of radicals required for the grafting reaction is large, the change in molecular mass of the polyolefin leads to a considerable modification of its viscosity in the molten state.
These graftings generally take place in an extruder. The viscosity of the grafted polyethylene is so high that it can no longer be extruded; the viscosity of the grafted polypropylene is so low that it too can no longer be extruded.
These phenomena reduce the amount of reactive functions which can be incorporated onto the polyolefin by radical grafting of functional monomers.
EP 617,063 describes the grafting of mixtures of (i) polypropylene homopolymers or of polypropylene containing a little ethylene and (ii) of ethylene/propylene copolymers which may contain ethylene predominantly. The amount of monomer to be grafted which is added to the mixture of (i) and (ii) is not more than 0.35% by weight of (i) and (ii). The grafted product obtained is not a coextrusion binder, but it is added to polypropylenes loaded with glass fibres.
The aim of the invention is to produce mixtures of (A) and (B) which may contain, for example, 3 to 5% by weight of grafts.
The Applicant has discovered that it is possible to graft large amounts of functional monomer onto mixtures of polyethylene and polypropylene. The increase in molecular mass of the polyethylene is compensated for by the decrease in molecular mass of the polypropylene present during the radical grafting reaction. The Applicant has discovered that it is possible to manufacture them in the molten state with conventional tools for the extrusion or mixing of plastics. The products obtained by this method have a fluidity such that it is possible to use them readily in conventional processes for converting plastics, to mix them homogeneously with other polymers in the molten state, with conventional techniques under usual temperature conditions. In comparison, polyethylenes grafted to the same levels are very viscous and it is not possible to use them under normal conditions of conversion. Furthermore, it is not possible to mix them homogeneously with other polymers in the molten state with common techniques under usual temperature conditions.
The present invention also relates to a multilayer structure composed of a layer comprising the above binder, and directly attached to the latter a layer of nitrogen-containing or oxygen-containing polar resin such as a layer (E) of a polyamide resin, of a saponified copolymer of ethylene and of vinyl acetate, of a polyester resin, of an inorganic oxide deposited on a polymer such as PE, polyethylene terephthalate or EVOH, or alternatively a metal layer.
According to this form, the binder may be used as a protective film.
According to another variant, the invention also relates to the above structure and directly attached to it, on the binder side, a layer (F) based on polyolefin.
As regards the binder of the invention, (A) is chosen from polyethylene homo- or copolymers.
Comonomers which may be mentioned are
alpha-olefins, advantageously those having from 3 to 30 carbon atoms.
Examples of alpha-olefins having 3 to 30 carbon atoms as possible comonomers comprise propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4 methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene, 1-dococene, 1-tetracocene, 1-hexacocene, 1-octacocene and 1-triacontene. These alpha-olefins may be used alone or as a mixture of two or more than two.
unsaturated carboxylic acid esters such as, for example, alkyl (meth)acrylates, it being possible for the alkyls to have up to 24 carbon atoms.
Examples of alkyl acrylate or methacrylate are, in particular, methyl methacrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate and 2-ethylhexyl acrylate.
vinyl esters of saturated carboxylic acids such as, for example, vinyl acetate or propionate.
unsaturated epoxides.
Examples of unsaturated epoxides are, in particular:
aliphatic glycidyl esters and ethers such as allyl glycidyl ether, vinyl glycidyl ether, glycidyl maleate and itaconate, glycidyl acrylate and methacrylate, and
alicyclic glycidyl esters and ethers such as 2-cyclohexene 1-glycidyl ether, cyclohexene-4,5-diglycidyl carboxylate, cyclohexene-4-glycidyl carboxylate, 5-norbornene-2-methyl-2-glycidyl carboxylate and endocisbicyclo(2,2,1)-5-heptene-2, 3-diglycidyl dicarboxylate.
unsaturated carboxylic acids, their salts and their anhydrides.
Examples of unsaturated dicarboxylic acid anhydrides are, in particular, maleic anhydride, itaconic anhydride, citraconic anhydride and. tetrahydrophthalic anhydride.
dienes such as, for example, 1,4-hexadiene.
(A) may comprise several comonomers.
Advantageously, the polymer (A), which may be a mixture of several polymers, comprises at least 50% and preferably 75% (on a molar basis) of ethylene. The density of (A) may be between 0.86 and 0.98 g/cm
3
. The MFI (viscosity index at 190° C., 2.16 kg) is advantageously between 1 and 1000 g/10 min.
Examples of polymers (A) which may be mentioned are:
low density polyethylene (LDPE)
high density polyethylene (HDPE)
linear low density polyethylene (LLDPE)
very low density polyethylene (VLDPE)
the polyethylene obtained by metallocene catalysis, that is to say the polymers obtained by copolymerization of ethylene and alpha-olefin such as propylene, butene, hexene or octene, in the presence of a monosite catalyst consisting generally of a zirconium or titanium atom and of two cyclic alkyl molecules linked to the metal. More specifically, the metallocene catalysts are usually compounds of two cyclopentadiene rings linked to the metal. These catalysts are often used with aluminoxanes as cocatalysts or activators, preferably methylaluminoxane (MAO). Hafnium may also be used as
Breysse Laurent
Robert Patrice
Aylward D.
Dawson Robert
Elf Atochem S.A.
Smith , Gambrell & Russell, LLP
LandOfFree
Coextrusion binder based on a mixture of cografted polyolefins does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coextrusion binder based on a mixture of cografted polyolefins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coextrusion binder based on a mixture of cografted polyolefins will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2971286