FR2740381A1 - Polymer mixtures with polyolefin matrix and a dispersed phase of polyamide alloy - Google Patents

Abstract

Polymer mixtures comprising (i) a matrix (A) comprising a polyolefin (A1) and/or a functionalised polyolefin (A2) and (ii) a dispersed phase comprised of an alloy (B) with a polyamide matrix, comprising e.g. a polyamide (B1), a functionalised polyolefin (B2) and optionally a polyolefin (B3).

Description

METHOD FOR MANUFACTURING EXTRUSION OBJECT
A MULTILAYER FILM BROYATE
The subject of the present invention is a process for producing an article from crushed multi-layer films, in particular multilayer films based on polyamide and polyolefin, said ground material possibly being mixed with a polyolefin.

 Multilayer films, especially polyamide / binder / polyolefin multilayer films, and more particularly polyamide (polyamide matrix) / binder / polyolefin alloy films, are increasingly used in various industrial fields. These multilayer films are manufactured by extrusion, and in particular by extrusion blow-molding. During its manufacture, the sheath is cut on both edges before separating the two films at the reel to simultaneously constitute two film reels. This leads to film waste (the selvedge). Furthermore, during sheath extrusion, it is necessary to optimize the extrusion blow-molding conditions in order to stabilize the bubble as much as possible, so as to obtain homogeneous characteristics. When starting, there is then film waste (due to irregularities in thickness, creases, appearance defects, etc.). Waste is also generated during other processes, for example the "cast-film" process.

 There is therefore a need to recycle the scrap or wastes obtained in the manufacture of these multilayer films, especially those obtained by the processes of blowing of sheath and cast-film.

 The present invention therefore provides a recycling of these films, in a method of manufacturing polymer object, in particular monolayer film.

Thus, the present invention provides a method of manufacturing an object consisting of extruding a ground material (i) of a multilayer film based on polyamide and polyolefin, optionally mixed with a polyolefin (ii)
According to one embodiment, the ground material (i) is mixed with a polyolefin (ii).

 According to another embodiment, the ground material is used as it is without adding polyolefin or another polymer.

 According to another embodiment, the multilayer film is a polyamide alloy multilayer film with a polyamide / binder / polyolefin matrix.

 According to yet another embodiment, the polyolefin of the multilayer film is substantially the same as the polyolefin (ii).

 In the embodiment where the film is an alloy-based film, this polyamide alloy may be a polyamide / compatibilizer / polyolefin alloy.

 According to this variant, the polyolefin of said alloy is substantially the same as the polyolefin of said multilayer film.

 According to one embodiment in which a polyolefin (ii) is mixed with the ground material, the polyolefin (ii) and the multilayer film mill (i) can be present in weight ratios of 5/95 to 95/5, preferably 15/85 to 75/25, preferably 25/75 to 50/50.

 According to one embodiment, the polyamide is PA6.

 According to another embodiment, the polyolefin (s) is (are) PE.

 Advantageously, the object manufactured according to the process of the invention is a monolayer film. It would not depart from the scope of the invention if this monolayer film was associated with other layers, that is to say, was part of a multilayer film.

 The invention also relates to the recycling of multilayer films based on polyamide and polyolefin in ground form in or by a method according to the invention.

 Advantageous results are obtained with multilayer polyamide alloy (polyamide matrix) / binder / polyolefin films.

 In the present application, the term "polyamide" refers to the condensation products of one or more alpha-omega-amino acids, such as those containing more than 5 carbon atoms, for example from 6 to 12 carbon atoms; examples of such amino acids are aminocaproic, amino-7-heptanol, amino-11 undecenoic and amino-12-dodecanoic acids; or one or more lactams corresponding to the amino acids above; examples of such lactams are caprolactam, oenanlactam and lauryllactam; or one or more substantially stoichiometric combinations of one or more aliphatic and / or cycloaliphatic and / or aromatic-aliphatic diamines, or salts thereof, with one or more aliphatic or aromatic carboxylic acid diacids, or salts thereof; examples of such diamines are hexamethylenediamine, dodecamethylenediamine, metaxylylenediamine, bis (4-aminocyclohexyl) methane (BACM), bis (3-methyl-4-aminocyclohexyl) methane (BMACM), and trimethylhexamethylenediamine, while examples of such diacids are terephthalic, isophthalic, adipic, azelaic, sebacic, suberic and docedanedicarboxylic acids; or any mixture of the aforementioned monomers; and any mixture of the resulting condensation products, optionally with other polymers compatible with the polyamides.

By way of example, the polyamide is PA6, PA6.6,
PA6,10, PAll, PA12, PA6,12 and PA12,12. The molecular weight of the polyamides may vary to a large extent, which one skilled in the art will appreciate.

 In the present application, the term "polyolefin" refers to homopolymers or copolymers of alpha-olefins or diolefins.

 These olefins are, for example, ethylene, propylene, butene-1, octene-1, butadiene.

By way of example, mention may be made of polyethylene PE, polypropylene PP and copolymers of ethylene with alpha-olefins. These polymers may be grafted with unsaturated carboxylic acid anhydrides such as maleic anhydride or unsaturated epoxides such as glycidyl methacrylate.

copolymers of ethylene with one or more product (s) chosen from: (i) unsaturated carboxylic acids, their salts, their esters; (ii) vinyl esters of saturated carboxylic acids such as vinyl acetate; (iii) unsaturated dicarboxylic acids, their salts, esters, hemiesters, anhydrides; and (iv) unsaturated epoxides.

These ethylene copolymers can be grafted with unsaturated dicarboxylic acid anhydrides or unsaturated epoxides.

block copolymers based on styrene, and in particular those consisting of polystyrene and polybutadiene (SBS) blocks, polystyrene and polyisoprene (SIS) blocks, and polystyrene and poly (ethylene-butylene) (SEBS) blocks, these copolymers being optionally maleicised; .

The abovementioned copolymers can be copolymerized randomly or sequentially and have a linear or branched structure.

This term polyolefin also covers mixtures of several of the polyolefins mentioned above.

By way of example, it is possible to use polyethylene (HDPE, LDPE or VLDPE); polypropylene; ethylene / alpha-olefin copolymers; ethylene / vinyl acetate copolymers (EVA); ethylene / alkyl (meth) acrylate / maleic anhydride copolymers, the maleic anhydride being grafted or copolymerized; the ethylene / alkyl (meth) acrylate / glycidyl methacrylate copolymers, the glycidyl methacrylate being grafted or copolymerized.

 The molecular weight of the polyolefins may vary to a large extent, which one skilled in the art will appreciate.

 For example, the molecular weight of the polyolefins can range from 1,000 to 1,000,000.

The term "substantially identical polyolefins" indicates that the respective physical and / or chemical and / or physicochemical characteristics are similar, for example, two homopolymers of the same monomer are substantially identical when their respective molecular weights are comparable, for example, a homopolyolefin is substantially identical to a copolyolefin when the comonomer of the latter is present in small amounts.
Low density PE (LDPE) are substantially identical, as are two high density PE (HDPE), two linear low density PE (LLDPE) or two very low density PE (VLDPE).

 In the present application, the term "binder" refers to the products commonly referred to as coextrusion binder, thermoplastic binder, hot melt bonding agent, etc.

By way of example, mention may be made of (co) polyolefins modified with an unsaturated carboxylic acid derivative (the modification being carried out by copolymerization, terpolymerization or grafting). Some of the above polyolefins can also be used as binder, provided that the content of functional groups is sufficient to ensure the adhesion of the layers to one another. Binder mixtures are also suitable.

Examples of such binders are given in the following patents, in a non-limiting manner, EP-A-210307, EP-A-33220,
EP-266994, FR-A-2132780, EP-A-171777, US-P-4758477, US-P4762890, US-P-4966810, US-P-4452942 and US-P-3658948.

Examples of these coextrusion binders are copolymers of ethylene copolymerized with butene, hexene, octene, optionally mixed with ethylene-propylene copolymers, grafted with maleic anhydride, said ethylene / alpha-olefin copolymers containing for example from 35 to 80% by weight of ethylene, the degree of grafting to anhydride being between 0.01 and 1% by weight, for example between 0.05 and 0.5t, relative to the total weight of copolymer; ethylene and vinyl acetate copolymers (EVA), maleic or non-maleic (maleic anhydride which can be grafted or terpolymerized), more particularly containing up to 40% by weight of vinyl acetate, of 0.01 to 1% by weight; grafted maleic anhydride or 0.1 to 10% by weight of terpolymerized maleic anhydride, based on the total weight of copolymer; ethylene and alkyl (meth) acrylate copolymers (such as methyl, ethyl or tert-butyl acrylate) and maleic anhydride, containing up to 40% by weight of alkyl (meth) acrylate and 0.01 to 10% by weight of maleic anhydride, relative to the total weight of copolymer.

 In the present application, the term "polyamide matrix polyamide alloy" refers to products comprising a polyamide, as described above; a polyolefin, as described above, and when it does not contain enough functionality to ensure compatibilization with the polyamide a compatibilizer; the polyolefin being present in the form of a dispersed phase in the polyamide phase, which is thus called polyamide matrix.

 The polyamide / polyolefin ratio in the alloy can vary over a wide range, which will be appreciated by those skilled in the art.

For example, the polyamide represents from 25 to 75%, advantageously from 30 to 70%, and more particularly from 50 to 70% by weight of the weight of the alloy.

 The compatibilizing agent is present in an amount sufficient to ensure compatibility, namely the dispersion of the polyolefin in the polyamide matrix in the form of nodules. The diameter of the nodules can be from 0.1 to 5pm.

For example, the compatibilizer may be up to 25% by weight of the polyolefin.

 The compatibilizing agent is a product known per se for compatibilizing polyamides and polyolefins.

Examples of these compatibilizing agents are - polyethylene, polypropylene, ethylene / propylene copolymers, ethylene / butene copolymers, all these products being grafted with maleic anhydride or glycidyl methacrylate; ethylene / alkyl (meth) acrylate / maleic anhydride copolymers, the maleic anhydride being grafted or copolymerized; ethylene / vinyl acetate / maleic anhydride copolymers, the maleic anhydride being grafted or copolymerized; the two preceding copolymers in which the anhydride is replaced in whole or in part by glycidyl methacrylate; ethylene / (meth) acrylic acid copolymers, and optionally their salts; ethylene / alkyl (meth) acrylate / glycidyl methacrylate copolymers, the glycidyl methacrylate being grafted or copolymerized; graft copolymers consisting of at least one monoamino oligomer of polyamide and an alpha-cycloolefin copolymer (co) polymer grafted with a monomer capable of reacting with the amine function of said oligomer;
Such alloys, or compatibilizing agents, are described in applications FR-A-2 291 225, EP-A-0 342 066 and
EP-A-0 218 665, the contents of which are incorporated in the present application.

In these alloys, elastomers such as maleated EPRs,
Maleated EPDM and others.

From the foregoing, it will be appreciated that the multilayer films which are recycled may consist of (i) a polyamide layer and a polyolefin layer in which a grafted polyolefin, for example of the type of the products used as binders, has been incorporated; (ii) a polyamide layer, a polyolefin layer and an intermediate binder layer; (iii) an alloy layer and a polyolefin layer in which a grafted polyolefin, for example of the type of products used as binders, has been incorporated; (iv) an alloy layer and a polyolefin layer mixed with binder in a sufficient amount; and (vi) an alloy layer, a polyolefin layer and an intermediate binder layer;
The multilayer films cited in the invention are obtained by conventional methods, namely coextrusion.

 Each layer of the multilayer film may contain conventional additives.

 In addition, additional layers may be present in the multilayer films.

 In multilayer films, the thickness is in a wide range that those skilled in the art will appreciate, for example between 20 and 300 μm. In addition, the proportions of the different layers, expressed in% of the final thickness of the multilayer film may also vary within a wide range that those skilled in the art will appreciate, for example, the ratio polyamide / polyolefin is between 9 / 1 and 1/9, advantageously between 3/1 and 1/3, while the binder, if present, can represent up to 30%, advantageously up to 20% of the final thickness.

 The multilayer film grind, which could also be called "regrind" is obtained by conventional grinding techniques, using knife mills. The straws obtained at the end of the passage in the mill may be used as such as ground material, or may be subjected to a densification step into granules. However, the term "comminuted" may also include waste directly from multilayer film manufacturing processes.

 Various multilayer film blends may also be recycled in accordance with the present invention.

 The invention is illustrated by the following example, which is given purely by way of illustration and not limiting the scope of the present invention.

Example.

 A multilayer film 70 μm in thickness is made in total, distributed as follows: outer layer / binder / inner layer: 30/10/30.

The outer layer is made of polyamide or polyamide-based alloy, while the inner layer is polyolefin. The polyolefin is Melt Index (MI) low density polyethylene (LDPE) of 0.3; the polyamide is PA6 of MI = 15-17; the alloy is an alloy marketed by Elf Atochem under the name Orgalloy, which is an alloy
PA6 / PE / terpolymer, said terpolymer being constituted by weight of 65% PA6 of MI = 15-17, 27% of LDPE of MI = 1 (at 190 OC) and 8% of an ethylene / acrylate copolymer butyl / maleic anhydride with 5.5% acrylate and 3.6% anhydride MI = 5; the binder is a linear low density polyethylene (LLDPE) grafted with maleic anhydride, sold by Elf Atochem under the name Orevac.

The temperature profiles of the Barmag extruder are:
PE: 230-250 ° C; Binder: 220-2300C; Alloy: 240-260 ° C; PA6: 240-2500C; head temperature: 2500C.

The operating conditions are as follows
Diameter of die: 150 mm; Gap: 0.7 mm; Print speed: 8.7 m / min; Inflation rate: 2.1; sheath width flat: 500 mm.

 The implementation is carried out until an amount of about 100 kg is obtained, after starting and optimization of the extruder settings.

 The films thus obtained, in the form of coils, are cut and then ground into flakes in a Pallman mill.

This mill is a hollow rotor mill with six knives, three of which are fixed. In the case of the PA / binder / PE film, the flakes exhibit a so-called "curling" phenomenon, as well as a relatively low apparent density. In the case of the alloy / binder / PE film, the flakes have a cross-section with an associated appearance of fragmentation. The apparent density for this last film is greater than for the previous film.

 These straws are then parboiled at 600C for 24 hours to remove any trace of residual moisture that would cause the formation of small bubbles.

Then, these parboiled straws are extruded with
PE in a Kaufman extruder.

The operating conditions are as follows
Diameter of die: 150 mm; Gap: 0.8 mm; Print speed: 9 m / min; Inflation rate: 2.12; sheath width flat: 500 mm.

The temperature profiles of the Kaufman extruder are those associated with PA6 or the Orgalloy alloy, namely
For tests with PA6 / binder / PE film flake in extruder: 240-2500C; in the lead: 2400C;
For tests with Orgalloy / binder / PE film flakes in extruder: 230-2500C; in the lead: 2400C;
On this extruder, 4 monolayer films with an average thickness of 50 μm are produced, the PE added to the ground material being a LDPE of MI = 0.3:
50% PE / 50% Orgalloy / binder / PE crushed material
B 25% PE / 75% Orgalloy / binder / PE crushed material
C 50% PE / 50% crushed PA6 / binder / PE
D 25% PE / 75% crushed PA6 / binder / PE
The films are manufactured without problems, without any segregation (no vault formation at the level of the feed chute). The films obtained are relatively translucent, milky, resistant and without moisture. The films obtained may have any required thickness, for example between 10 and 150 μm.

 In the case of the PA6 / binder / PE film, the material flow rate is 30 kg / h for screw speeds of 110 rpm and 60 rpm for the compositions C and D, respectively.

 In the case of the Orgalloy / binder / PE film, the material flow rate is 60 kg / h for screw speeds of 110 rpm and 60 rpm for compositions A and B, respectively.

 Thus, the polyamide alloy leads to unexpected results compared to the PA6, namely a very high material flow rate (with Orgalloy the flow rate obtained is twice that of the PA6), excellent extrudability, an excellent ability to to form films. Moreover, in the case of the alloy such as Orgalloy, it will not be necessary to extrude it in a special screw, such as a polyamide screw: the polyolefin extrusion devices do not have to be suitable for receiving the ground material of Orgalloy / binder / PE multilayer films.

 The results of the mechanical tests (tensile strength, tear resistance, "test test") carried out on a PE film and on the films A, B, C and D are given in Table 1 below.

 These results show that it is possible to recycle PA / binder / PE and alloy / binder / PE multilayer films. The results also show the surprising superiority of recycling films obtained from multilayer alloy / binder / PE films with respect to PA / binder / PE films, for example as regards the surface appearance properties and the mechanical properties of the films. final recycling films.

- Dart test: better impact resistance is obtained for films A and B; - Traction: better isotropy is obtained between the parallel direction and the direction perpendicular to the extrusion with the recycled alloy / binder / PE film; - Tear resistance: better tear resistance is obtained in the direction parallel to extrusion with films A and B.

 Of course, the present invention is not limited to the embodiments described but is capable of numerous variants easily accessible to those skilled in the art.

Table 1

STANDARD <SEP> TEST <SEP> UNIT <SEP> PE <SEP> A <SEP> B <SEP> C <SEP> D
<tb> ASTM <SEP> D882 <SEP> Traction
<tb> strip <SEP> (meaning <SEP> parallel <SEP> to
<tb> 1 = 15mm; <SEP> extrusion)
<tb> LO = 50mm; <SEP> Constraint <SEP> to <SEP> the <SEP> Mpa <SEP> 28.6 +/- 1.2 <SEP> 24.9 +/- 1.6 <SEP> 33.9 +/- 1 , 6 <SEP> 28.1 +/- 1.6 <SEP> 28.1 +/- 2.1
<tb> V = 500mm / min <SEP> rupture
<tb> Lengthening <SEP> to <SEP><SEP>%<SEP> 718 +/- 19 <SEP> 478 +/- 33 <SEP> 419 +/- 26 <SEP> 340 +/- 22 <SEP > 366 +/- 26
<tb> break
<tb> ASTM <SEP> D882 <SEP> Traction
<tb> strip <SEP> (meaning <SEP> perpendicular
<tb> 1 = 15mm; <SEP> to <SEP> extrusion
<tb> LO = 50mm; <SEP> Constraint <SEP> to <SEP><SEP> MPa <SEP> 22.8 +/- 1.8 <SEP> 23.4 +/- 1.3 <SEP> 23.4 +/- 1 , 4 <SEP> 12.3 +/- 1 <SEP> 20 +/- 0.6
<tb> V = 500mm / min <SEP> rupture
<tb> Lengthening <SEP> to <SEP><SEP>%<SEP> 918 +/- 22 <SEP> 720 +/- 30 <SEP> 588 +/- 62 <SEP> 68 +/- 12 <SEP > 325 +/- 76
<tb> break
<tb> NFT <SEP> 54-141 <SEP> Resistance <SEP> to <SEP> la
<tb> (score <SEP> 20mm) <SEP> tear <SEP> (Test specimen
<tb> to <SEP> radius <SEP> constant)
<tb> meaning <SEP> parallel <SEP> to <SEP> N <SEP> 3.31 +/- 0.82 <SEP> 0.90 +/- 0.15 <SEP> 0.66 +/- 0 , 08 <SEP> 0.17 +/- 0.02 <SEP> 0.44 +/- 0.05
<tb> extrusion
<tb> meaning <SEP> perpendicular <SEP> to <SEP> N <SEP> 5.72 +/- 0.53 <SEP> 3.40 +/- 0.17 <SEP> 2.70 +/- 0 , 11 <SEP> 4.08 +/- 0.32 <SEP> 2.04 +/- 0.16
<tb> extrusion
<tb> NFT <SEP> 54-109 <SEP> Mass <SEP> of <SEP> breaking <SEP> at <SEP> g <SEP> 153 <SEP> 294 <SEP> 278 <SEP> lower <SEP> lower
<tb> Method <SEP> A <SEP> shock <SEP> (for <SEP> 50% <SEP> from <SEP> to <SEP> 33g <SEP> to <SEP> 33g
<tb> (shock <SEP> lower <SEP> break)
<tb> to <SEP> 300g) <SEP> Thickness <SEP> of <SEP> film <SEP> m <SEP> 53 <SEP> 53 <SEP> 53 <SEP> 55 <SEP> 59
<Tb>

Claims (11)

1. A method of manufacturing an object consisting of the extrusion of a ground material (i) of a multilayer film based on polyamide and polyolefin, optionally mixed with a polyolefin (ii). 2. The method of claim 1, wherein the ground material (i) is mixed with a polyolefin (ii). The method of claim 2, wherein the polyolefin of the multilayer film is substantially the same as the polyolefin (ii). 4. The method of claim 1 or 2, wherein the multilayer film is a polyamide alloy multilayer film polyamide matrix / binder / polyolefin. The method of claim 4, wherein the polyamide alloy is a polyamide / compatibilizer / polyolefin alloy. The method of claim 5, wherein the polyolefin of said alloy is substantially the same as the polyolefin of said multilayer film. The process according to any one of claims 2 to 6, wherein the polyolefin (ii) and the multilayer film grind (i) are present in weight ratios of 5/95 to 95/5, preferably 15/95. 85 to 75/25, advantageously 25/75 to 50/50. The method of any one of claims 1 to 6, wherein the polyamide is PA6. 9. Process according to any one of claims 1 to 8, wherein the polyolefin (s) is (are) PE. The method of any one of claims 1 to 9, wherein the object is a monolayer film. 11. Recycling of multilayer polyamide-based films and polyolefin in ground form in a process according to any one of claims 1 to 10.