U.S. patent application number 11/154422 was filed with the patent office on 2006-01-12 for multilayer structure having a layer based on polyamide and on hdpe.
Invention is credited to Gaelle Bellet, Philippe Blondel, Benoit Brule, Jean-Jacques Flat.
Application Number | 20060008604 11/154422 |
Document ID | / |
Family ID | 35541694 |
Filed Date | 2006-01-12 |
United States Patent
Application |
20060008604 |
Kind Code |
A1 |
Flat; Jean-Jacques ; et
al. |
January 12, 2006 |
Multilayer structure having a layer based on polyamide and on
HDPE
Abstract
The present invention relates to a structure successively
comprising: a first layer of high density polyethylene (HDPE), a
tie layer, a second layer of EVOH or of a blend based on EVOH,
optionally a tie layer, a third layer of a blend comprising, by
weight, the total being 100%: 50 to 90% of polyamide (A) having a
conversion temperature of at most 230.degree. C., 1 to 30% of high
density polyethylene (HDPE), 5 to 30% of an impact modifier chosen
from elastomers and very low density polyethylenes, at least one of
the HDPE and of the impact modifier being functionalized, in all or
part, the layers being coextrudable. The present invention also
relates to devices for the transfer or storage of fluids and more
particularly to pipes, tanks, conduits, bottles and containers
composed of the above structure in which the layer of the blend of
polyamide (A) and of HDPE is in direct contact with the fluid
present or transported
Inventors: |
Flat; Jean-Jacques;
(Goupillieres, FR) ; Bellet; Gaelle; (Evreux,
FR) ; Brule; Benoit; (Bernay, FR) ; Blondel;
Philippe; (Bernay, FR) |
Correspondence
Address: |
Arkema Inc.
2000 Market St.
Philadelphia
PA
19103
US
|
Family ID: |
35541694 |
Appl. No.: |
11/154422 |
Filed: |
June 16, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60585494 |
Jul 2, 2004 |
|
|
|
60631933 |
Nov 30, 2004 |
|
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Current U.S.
Class: |
428/35.4 ;
428/36.7 |
Current CPC
Class: |
Y10T 428/1341 20150115;
Y10T 428/1383 20150115; B32B 27/32 20130101 |
Class at
Publication: |
428/035.4 ;
428/036.7 |
International
Class: |
B65D 1/00 20060101
B65D001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 18, 2004 |
FR |
04.06635 |
Oct 1, 2004 |
FR |
04.10391 |
Claims
1. A structure comprising in order: a) a first layer of high
density polyethylene (HDPE), b) a tie layer, c) a second layer of
EVOH or of a blend based on EVOH, d) optionally a tie layer, e) a
third layer of a blend comprising, by weight, the total being 100%:
50 to 90% of polyamide (A) having a conversion temperature of at
most 230.degree. C., 1 to 30% of high density polyethylene (HDPE),
5 to 30% of an impact modifier chosen from elastomers and very low
density polyethylenes, wherein the HDPE and/or the impact modifier
is functionalized, in whole or in part, wherein the layers are
coextrudable.
2. The structure according to claim 1, wherein said polyamide (A)
is polyamide 6/6-6 or polyamide 6/12.
3. The structure according to claim 1, wherein the proportion of
functionalized HDPE and/or of functionalized modifier with respect
to the combined functionalized or nonfunctionalized HDPE and
functionalized or nonfunctionalized impact modifier in the third
layer (e) is between 0 and 70 percent by weight.
4. The structure according to claim 3, wherein the proportion of
functionalized HDPE and/or of functionalized modifier with respect
to the combined functionalized or nonfunctionalized HDPE and
functionalized or nonfunctionalized impact modifier in the third
layer (e) is between 5 and 60 percent by weight.
5. The structure according to claim 4, in which the proportion of
functionalized HDPE and/or of fuctionalized modifier with respect
to the combined functionalized or nonfunctionalized HDPE and
functionalized or nonfunctionalized impact modifier in the third
layer (e) is between 20 and 60 percent by weight.
6. The structure according to claim 1, wherein in layer (e) the
HDPE is not functionalized and the impact modifier is
functionalized in all or part.
7. The structure according to claim 1, wherein the impact modifier
is an ethylene-propylene rubber (EPR) or an
ethylene-propylene-diene monomer elastomer (EPDM).
8. The structure according to claim 1, wherein the functionalized
impact modifier is an EPR or an EPDM grafted by maleic
anhydride.
9. The structure according to claim 1, wherein the proportions of
the blend of the third layer are, the total being 100%: 55 to 80%
of polyamide (A), 10 to 20% of high density polyethylene (HDPE), 10
to 30% of impact modifier.
10. The structure according to claim 1, in which a layer of
recycled polymers is positioned between the first layer and the tie
layer.
11. The structure according to claim 10, in which the layer of
recycled polymers further comprises HDPE and/or functionalized
polyolefins.
12. A devices for the transfer or storage of fluids comprising the
structure according to claim 1, in which the third layer (e) is in
direct contact with the fluid present or transported.
13. The device according to claim 12 wherein said device is
selected from the group consisting of a pipe, a tank, a conduit, a
bottle, and a container.
Description
[0001] This application claims benefit, under U.S.C. .sctn. 119(a)
of French National Applications Number 04.06635, filed Jun. 18,
2004; and 04.10391, filed Oct. 01, 2004 ; and also claims benefit,
under U.S.C. .sctn. 119(e) of U.S. provisional applications
60/585494, filed Jul. 2, 2004 and 60/631933 filed Nov. 30,
2004.
FIELD OF THE INVENTION
[0002] The present invention relates to a multilayer structure
having a layer based on polyamide and on HDPE (high density
polyethylene). It also relates to a tank composed of this structure
having this layer in direct contact with the fluid contained in the
tank. The layer based on polyamide and on HDPE of the structures of
the invention constitutes one of the faces of the structure, that
is to say that it is not inside the structure (sandwich). These
structures are of use in the manufacture of devices for the
transfer or storage of fluids and more particularly pipes, tanks,
tank conduits, that is to say the pipe which is used to fill the
tank, bottles and containers in which the layer based on polyamide
and on HDPE is in contact with the fluid. It is of particular use
for tanks.
[0003] The invention is of use for a fluid, such as motor vehicle
petrol, by preventing losses through the structure, so as not to
pollute the environment. It is also of use for liquids comprising
volatile substances by preventing depletion of the liquid in this
volatile substance. The invention is also of use for the liquid
coolant of the engines, for the oil and for the fluid of the
air-conditioning system.
BACKGROUND OF THE INVENTION
[0004] Patent EP 742 236 discloses petrol tanks composed of five
layers, which are respectively:
[0005] high density polyethylene (HDPE);
[0006] a tie;
[0007] a polyamide (PA) or a copolymer having ethylene units and
vinyl alcohol units (EVOH);
[0008] a tie;
[0009] HDPE. [0010] A sixth layer can be added between one of the
tie layers and one of the HDPE layers. This sixth layer is
composed, for example, of the manufacturing scrap material
resulting from the forming of the tanks or, in a much smaller
amount, of tanks which have failed specification. This scrap
material and these tanks which have failed specification are
ground. This ground material is subsequently remelted and directly
extruded on the plant for the coextrusion of the tanks. This ground
material might also be melted and regranulated by an extrusion
device, such as a twin-screw or single-screw extruder, before being
reused.
[0011] According to one alternative form, the recycled product can
be blended with the HDPE of the two outermost layers of the tank.
It is possible, for example, to blend the granules of recycled
product with the granules of virgin HDPE of these two layers. It is
also possible to use any combination of these recycling operations.
The level of recycled material can represent up to 50% of the total
weight of the tank.
[0012] U.S. Pat. No. 6,177,162 discloses a tube comprising an inner
layer comprising a blend of polyamide and of polyolefin with a
polyamide matrix and an outer layer comprising a polyamide. These
polyamide-based tubes are of use for the transportation of petrol
and more particularly for conveying the petrol from the tank of the
motor vehicle to the engine and also, but with a larger diameter,
for the transportation of hydrocarbons in service stations between
the distribution pumps and the underground storage reservoirs.
[0013] According to another form of the invention, it is possible
to position, between the inner and outer layers, a layer of a
polymer comprising ethylene units and vinyl alcohol units (EVOH).
Use is advantageously made of the structure: inner
layer/EVOH/tie/outer layer.
[0014] The tanks disclosed in EP 742 236, and which do not have the
barrier layer in direct contact with the petrol, certainly have
barrier properties but they are not sufficient when very low petrol
losses are being looked for. EP 731 308 discloses pipes which have
their outer layer made of polyamide and the barrier layer in direct
contact with the petrol; the layer made of polyamide is necessary
for the mechanical strength of the combined product.
[0015] Patent Application 2005089701 discloses a structure
successively comprising:
[0016] a first layer of high density polyethylene (HDPE),
[0017] a tie layer,
[0018] a second layer of EVOH or of a blend based on EVOH,
[0019] optionally a third layer of polyamide or of a blend of
polyamide and of polyolefin. Numerous blends of polyamide and of
polyolefin which can constitute the third layer are described in
this patent. It has now been found that this third layer is
necessary and, furthermore, that it has to comprise HDPE in order
to obtain good barrier properties. Furthermore, the conversion
temperature of the polyamide of this third layer must not be too
high in order not to be too far from that of the EVOH.
SUMMARY OF THE INVENTION
[0020] The present invention relates to a structure successively
comprising: [0021] a first layer of high density polyethylene
(HDPE), [0022] a tie layer, [0023] a second layer of EVOH or of a
blend based on EVOH, [0024] optionally a tie layer, [0025] a third
layer of a blend comprising, by weight, the total being 100%:
[0026] 50 to 90% of polyamide (A) having a conversion temperature
of at most 230.degree. C.,
[0027] 1 to 30% of high density polyethylene (HDPE),
[0028] 5 to 30% of an impact modifier chosen from elastomers and
very low density polyethylenes,
[0029] at least one of the HDPE and of the impact modifier being
functionalized, in all or part, the layers being coextrudable.
[0030] Use may be made of a blend of different HDPEs. It can be a
blend of different nonfunctionalized HDPEs, of a nonfunctionalized
HDPE and of the same HDPE but functionalized, of a
nonfunctionalized HDPE and of another HDPE but functionalized or of
two different grafted HDPEs, or any combination of these
possibilities.
[0031] Use may be made of a blend of different impact modifiers. It
can be a blend of different nonfunctionalized impact modifiers, of
a nonfunctionalized impact modifier and of the same impact modifier
but functionalized, of a nonfunctionalized impact modifier and of
another impact modifier but functionalized, of two different
functionalized impact modifiers or of a functionalized impact
modifier and of a functionalized HDPE with optionally a
nonfunctionalized impact modifier and optionally a
nonfunctionalized HDPE, or any combination of these
possibilities.
[0032] The layers are "coextrudable", meaning that they are in the
same rheology range to form, for example, a parison which can be
blow-moulded to form a hollow body or an extruded tube.
[0033] The proportion of functional groups of the HDPE and/or of
the impact modifier must be sufficient for the layer based on
polyamide (A) and on HDPE to have mechanical strength but not too
great in order for the viscosity not to be so high that the layer
is no longer coextrudable.
[0034] The present invention also relates to devices for the
transfer or storage of fluids and more particularly to pipes,
tanks, conduits, bottles and containers composed of the above
structure in which the layer of the blend of polyamide (A) and of
HDPE is in direct contact with the fluid present or transported.
These devices can be manufactured by conventional techniques of the
industry of thermoplastic polymers, such as coextrusion and
coextrusion blow-moulding.
DETAILED DESCRIPTION OF THE INVENTION
[0035] As regards the first layer, high density polyethylene (HDPE)
is described in Kirk-Othmer, 4th edition, Vol. 17, pages 704 and
724-725. It is, according to ASTM D 1248-84, an ethylene polymer
having a density of at least 0.940. The name HDPE relates both to
ethylene homopolymers and to copolymers of ethylene with small
proportions of .alpha.-olefin. The density is advantageously
between 0.940 and 0.965. In the present invention, the MFI of the
HDPE is advantageously between 0.1 and 50. Mention may be made, as
examples, of Eltex B 2008.RTM., with a density of 0.958 and an MFI
of 0.9 (in g/10 min at 190.degree. C. under 2.16 kg),
Finathene.RTM. MS201B from Fina and Lupolen.RTM. 4261 AQ from BASF.
As regards the high density polyethylene of the first layer, its
density is advantageously between 0.940 and 0.965 and the MFI is
between 0.1 and 5 g/10 min. (190.degree. C., 5 kg).
[0036] As regards the second layer, the EVOH copolymer is also
known as saponified vinyl acetate/ethylene copolymer. The
saponified vinyl acetate/ethylene copolymer to be employed
according to the present invention is a copolymer having an
ethylene content of 20 to 70 mol %, preferably of 25 to 70 mol %,
the degree of saponification of its vinyl acetate component being
not less than 95 mol %. With an ethylene content of less than 20
mol %, the barrier properties under conditions of high humidity are
not as great as would be desired, while an ethylene content
exceeding 70 mol % leads to declines in the barrier properties.
When the degree of saponification or of hydrolysis is less than 95
mol %, the barrier properties are lost.
[0037] The term "barrier properties" is understood to mean
impermeability to gases and to liquids and in particular to oxygen
and to petrol for motor vehicles. The invention relates more
particularly to the barrier to petrol for motor vehicles.
[0038] Among these saponified copolymers, those which have melt
flow indices in the range from 0.5 to 100 g/10 minutes are of
particular use. Advantageously, the MFI is chosen between 5 and 30
(g/10 min at 230.degree. C. under 2.16 kg); "MFI" is the
abbreviation for Melt Flow Index.
[0039] It is understood that this saponified copolymer can comprise
small proportions of other comonomer ingredients, including
.alpha.-olefins, such as propylene, isobutene, .alpha.-octene,
.alpha.-dodecene, .alpha.-octadecene, and the like, unsaturated
carboxylic acids or their salts, partial alkyl esters, complete
alkyl esters, nitrites, amides and anhydrides of the said acids,
and unsaturated sulphonic acids or their salts.
[0040] With regard to the blends based on EVOH, they are such that
the EVOH forms the matrix, that is to say that it represents at
least 40% by weight of the blend and preferably at least 50%. The
other constituents of the blend are chosen from polyolefins,
polyamides or impact modifiers which are optionally functionalized.
The impact modifier can be chosen from elastomers, copolymers of
ethylene and of an olefin having 4 to 10 carbon atoms (for example,
ethylene-octene copolymers), and very low density polyethylenes.
Mention may be made, as examples of elastomers, of EPR and EPDM.
EPR (abbreviation for Ethylene-Propylene Rubber) denotes
ethylene-propylene elastomers and EPDM denotes
ethylene-propylene-diene monomer elastomers.
[0041] As first example of these blends based on EVOH of the second
layer, mention may be made of the compositions comprising (by
weight):
[0042] 55 to 99.5 parts of EVOH copolymer,
[0043] 0.5 to 45 parts of polypropylene and of compatibilizing
agent, their proportions being such that the ratio of the amount of
polypropylene to the amount of compatibilizing agent is between 1
and 5. [0044] Advantageously, the ratio of the MFI of the EVOH to
the MFI of the polypropylene is greater than 5 and preferably
between 5 and 25. Advantageously, the MFI of the polypropylene is
between 0.5 and 3 (in g/10 min at 230.degree. C. under 2.16 kg).
According to an advantageous form, the compatibilizing agent is a
polyethylene carrying polyamide grafts and it results from the
reaction (i) of a copolymer of ethylene and of a grafted or
copolymerized unsaturated monomer X with (ii) a polyamide. The
copolymer of ethylene and of a grafted or copolymerized unsaturated
monomer X is such that X is copolymerized and it can be chosen from
ethylene/maleic anhydride copolymers and ethylene/alkyl
(meth)acrylate/maleic anhydride copolymers, these copolymers
comprising from 0.2 to 10% by weight of maleic anhydride and from 0
to 40% by weight of alkyl (meth)acrylate.
[0045] According to another advantageous form, the compatibilizing
agent is a polypropylene carrying polyamide grafts which results
form the reaction (i) of a homopolymer or of a copolymer of
propylene comprising a grafted or copolymerized unsaturated monomer
X with (ii) a polyamide. Advantageously, X is grafted. The monomer
X is advantageously an unsaturated carboxylic acid anhydride, such
as, for example, maleic anhydride.
[0046] As second example of these blends based on EVOH of the
second layer, mention may be made of the compositions
comprising:
[0047] 50 to 98% by weight of an EVOH copolymer,
[0048] 1 to 50% by weight of a polyethylene,
[0049] 1 to 15% by weight of a compatibilizing agent composed of a
blend of an LLDPE polyethylene or metallocene polyethylene and of a
polymer chosen from elastomers, very low density polyethylenes and
metallocene polyethylenes, the blend being cografted by an
unsaturated carboxylic acid or a functional derivative of this
acid.
[0050] Advantageously, the compatibilizing agent is such that the
MFI.sub.10/MFI.sub.2 ratio is between 5 and 20, where MFI.sub.2 is
the melt flow index at 190.degree. C. under a load of 2.16 kg,
measured according to ASTM D1238, and MFI.sub.10 is the melt flow
index at 190.degree. C. under a load of 10 kg, according to ASTM
D1238.
[0051] As third example of these blends based on EVOH of the second
layer, mention may be made of the compositions comprising:
[0052] 50 to 98% by weight of an EVOH copolymer,
[0053] 1 to 50% by weight of an ethylene/alkyl (meth)acrylate
copolymer,
[0054] 1 to 15% by weight of a compatibilizing agent resulting from
the reaction (i) of a copolymer of ethylene and of a grafted or
copolymerized unsaturated monomer X with (ii) a copolyamide.
[0055] Advantageously, the copolymer of ethylene and of a grafted
or copolymerized unsaturated monomer X is such that X is
copolymerized and this is a copolymer of ethylene and of maleic
anhydride or a copolymer of ethylene, of an alkyl (meth)acrylate
and of maleic anhydride.
[0056] Advantageously, these copolymers comprise from 0.2 to 10% by
weight of maleic anhydride and from 0 to 40% by weight of alkyl
(meth) acrylate.
[0057] As fourth example of these blends based on EVOH of the
second layer, mention may be made of the compositions
comprising:
[0058] 50 to 98% by weight of an EVOH copolymer,
[0059] 2 to 50% by weight of an elastomer which is optionally
functionalized in all or part or of a blend of a functionalized
elastomer and of another nonfunctionalized elastomer.
[0060] As regards the blend of polyamide (A) and of HDPE of the
third layer, the term "conversion temperature" is understood to
mean the temperature at which it is coextruded with the material of
the other layers and/or coextruded and blow-moulded with the
material of the other layers. For semicrystalline polyamides, this
is a temperature above the melting point (usually denoted by M.p.)
and, for amorphous polyamides, this is, of course, a temperature
above the Tg (glass transition temperature). The term "above" is
understood to mean generally a difference of 10 to 50.degree.
C.
[0061] This polyamide (A) is chosen from the products which
comprise units originating:
[0062] from one or more amino acids, such as aminocaproic acid,
7-aminoheptanoic acid, 11-aminoundecanoic acid and
12-aminododecanoic acid, or from one or more lactams, such as
caprolactam, enantholactam and lauryllactam;
[0063] from one or more salts or mixtures of diamines with diacids.
Mention may be made, as examples of diacids, of isophthalic acid,
terephthalic acid or dicarboxylic acids having from 6 to 18 carbon
atoms, such as adipic acid, azelaic acid, suberic acid, sebacic
acid and dodecanedicarboxylic acid. The diamine can be an aliphatic
diamine having from 6 to 18 atoms, it can be an arylic and/or
saturated cyclic diamine. Mention may be made, as examples, of
hexamethylenediamine, piperazine, tetramethylenediamine,
octamethylenediamine, decamethylenediamine, dodecamethylenediamine,
1,5-diaminohexane, 2,2,4-trimethyl-1,6-diaminohexane,
polyoldiamines, isophoronediamine (IPD),
methylpentamethylenediamine (MPDM), bis(aminocyclohexyl)methane
(BACM), or bis(3-methyl-4aminocyclohexyl)methane (BMACM).
[0064] Use may also advantageously be made of copolyamides. Mention
may be made of the copolyamides resulting from the condensation of
at least two .alpha.,.omega.-aminocarboxylic acids or of two
lactams or of a lactam and of an .alpha.,.omega.-aminocarboxylic
acid. Mention may also be made of the copolyamides resulting from
the condensation of at least one .alpha.-.omega.-aminocarboxylic
acid (or one lactam), at least one diamine and at least one
dicarboxylic acid.
[0065] Mention may be made, as examples of lactams, of those which
have from 3 to 12 carbon atoms on the main ring and which can be
substituted. Mention may be made, for example, of
.beta.,.beta.-dimethylpropiolactam,
.alpha.,.alpha.-dimethylpropiolactam, amylolactam, caprolactam,
capryllactam and lauryllactam.
[0066] Mention may be made, as examples of
.alpha.,.omega.-aminocarboxylic acids, of aminoundecanoic acid and
aminododecanoic acid. Mention may be made, as examples of
dicarboxylic acids, of adipic acid, sebacic acid, isophthalic acid,
butanedioic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic
acid, the sodium or lithium salt of sulphoisophthalic acid,
dimerized fatty acids (these dimerized fatty acids have a dimer
content of at least 98% and are preferably hydrogenated) and
dodecanedioic acid HOOC-(CH.sub.2).sub.10-COOH.
[0067] Mention may be made, as examples of copolyamides, of
copolymers of caprolactam and of lauryllactam (PA 6/12), copolymers
of caprolactam, of adipic acid and of hexamethylenediamine (PA
6/6-6), copolymers of caprolactam, of lauryllactam, of adipic acid
and of hexamethylenediamine (PA 6/12/6-6), copolymers of
caprolactam, of lauryllactam, of 11-aminoundecanoic acid, of
azelaic acid and of hexamethylenediamine (PA 6/6-9/11/12),
copolymers of caprolactam, of lauryllactam, of 11-aminoundecanoic
acid, of adipic acid and of hexamethylenediamine (PA 6/6-6/11/12)
or copolymers of lauryllactam, of azelaic acid and of
hexamethylenediamine (PA 6-9/12). [0068] All these polyamides (A)
are known per se and are manufactured according to the usual
processes for polyamides.
[0069] Advantageously, the copolyamide is chosen from PA 6/12 and
PA 6/6-6.
[0070] Polyamide blends can be used. Advantageously, the relative
viscosity, measured in 96% sulphuric acid, is between 2 and 5.
[0071] It would not be departing from the scope of the invention to
replace a portion of the polyamide (A) with a copolymer comprising
polyamide blocks and polyether blocks, that is to say to use a
blend comprising at least one of the above polyamides and at least
one copolymer comprising polyamide blocks and polyether blocks.
[0072] The copolymers comprising polyamide blocks and polyether
blocks result from the copolycondensation of polyamide sequences
comprising reactive ends with polyether sequences comprising
reactive ends, such as, inter alia:
[0073] 1) Polyamide sequences comprising diamine chain ends with
polyoxyalkylene sequences comprising dicarboxyl chain ends.
[0074] 2) Polyamide sequences comprising dicarboxyl chain ends with
polyoxyalkylene sequences comprising diamine chain ends obtained by
cyanoethylation and hydrogenation of aliphatic
.alpha.,.omega.-dihydroxylated polyoxyalkylene sequences, known as
polyetherdiols.
[0075] 3) Polyamide sequences comprising dicarboxyl chain ends with
polyetherdiols, the products obtained being, in this specific case,
polyetheresteramides. Use is advantageously made of these
copolymers.
[0076] The polyamide sequences comprising dicarboxyl chain ends
originate, for example, from the condensation of
.alpha.,.omega.-aminocarboxylic acids, of lactams or of
dicarboxylic acids and diamines in the presence of a chain-limiting
dicarboxylic acid.
[0077] The polyether can, for example, be a polyethylene glycol
(PEG), a polypropylene glycol (PPG) or a polytetramethylene glycol
(PTMG). The latter is also known as polytetrahydrofuran (PTHF).
[0078] The number-average molar mass {overscore (Mn)} of the
polyamide sequences is between 300 and 15 000 and preferably
between 600 and 5000. The mass {overscore (Mn)} of the polyether
sequences is between 100 and 6000 and preferably between 200 and
3000.
[0079] The polymers comprising polyamide blocks and polyether
blocks can also comprise randomly distributed units. These polymers
can be prepared by the simultaneous reaction of the polyether and
of the precursors of the polyamide blocks.
[0080] For example, polyetherdiol, a lactam (or an
.alpha.,.omega.-amino acid) and a chain-limiting diacid can be
reacted in the presence of a small amount of water. A polymer is
obtained which has essentially polyether blocks and polyamide
blocks, the latter being of highly variable length, but also the
various reactants which have reacted randomly, which are
distributed statistically along the polymer chain.
[0081] These polymers comprising polyamide blocks and polyether
blocks, whether they originate from the copolycondensation of
polyamide and polyether sequences prepared beforehand or from a
one-stage reaction, exhibit, for example, Shore D hardnesses which
can be between 20 and 75 and advantageously between 30 and 70 and
an intrinsic viscosity of between 0.8 and 2.5, measured in
meta-cresol at 250.degree. C. for an initial concentration of 0.8
g/100 ml. The MFI values can be between 5 and 50 (235.degree. C.
under a load of 1 kg).
[0082] The polyetherdiol blocks are either used as is and
copolycondensed with polyamide blocks comprising carboxyl ends or
they are aminated, in order to be converted into polyetherdiamines,
and condensed with polyamide blocks comprising carboxyl ends. They
can also be blended with polyamide precursors and a chain-limiting
agent in order to prepare polymers comprising polyamide blocks and
polyether blocks having statistically distributed units.
[0083] Polymers comprising polyamide and polyether blocks are
disclosed in U.S. Pat. No. 4,331,786, U.S. Pat. No. 4,115,475, U.S.
Pat. No. 4,195,015, U.S. Pat. No. 4,839,441, U.S. Pat. No.
4,864,014, U.S. Pat. No. 4,230,838 and U.S. Pat. No. 4,332,920.
[0084] The ratio of the amount of copolymer comprising polyamide
blocks and polyether blocks to the amount of polyamide is
advantageously between 10/90 and 60/40, by weight.
[0085] As regards the HDPE of the third layer, its density is
advantageously between 0.940 and 0.965 and the MFI between 1 and 10
g/10 min. (190.degree. C., 5 kg).
[0086] As regards the impact modifier and first the elastomers,
mention may be made of SBS, SIS and SEBS block polymers and
ethylene/propylene (EPR) or ethylene/propylene/diene (EPDM)
elastomers. With regard to the very low density polyethylenes,
these are, for example, metallocenes with a density, for example,
between 0.860 and 0.900.
[0087] Use is advantageously made of an ethylene/propylene (EPR) or
ethylene/propylene/diene (EPDM) elastomer. The functionalization
can be introduced by grafting or copolymerization with an
unsaturated carboxylic acid. It would not be departing from the
scope of the invention to use a functional derivative of this acid.
Examples of unsaturated carboxylic acids are those having 2 to 20
carbon atoms, such as acrylic acid, methacrylic acid, maleic acid,
fumaric acid and itaconic acid. The functional derivatives of these
acids comprise, for example, the anhydrides, the ester derivatives,
the amide derivatives, the imide derivatives and the metal salts
(such as the alkali metal salts) of the unsaturated carboxylic
acids.
[0088] Unsaturated dicarboxylic acids having 4 to 10 carbon atoms
and their functional derivatives, particularly their anhydrides,
are particularly preferred grafting monomers. These grafting
monomers comprise, for example, maleic acid, fumaric acid, itaconic
acid, citraconic acid, allylsuccinic acid,
cyclohex-4-ene-1,2-dicarboxylic acid,
4-methylcyclohex-4-ene-1,2-dicarboxylic acid,
bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid,
x-methylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, maleic
anhydride, itaconic anhydride, citraconic anhydride, allylsuccinic
anhydride, cyclohex-4-ene-1,2-dicarboxylic anhydride,
4-methylcyclohex-4-ene-1,2-dicarboxylic anhydride,
bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride and
x-methylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride. Use is
advantageously made of maleic anhydride.
[0089] Various known processes can be used to graft a grafting
monomer to a polymer. For example, this can be carried out by
heating the polymers at high temperature, approximately 150.degree.
to approximately 300.degree. C., in the presence or in the absence
of a solvent and with or without a radical generator. The amount of
the grafting monomer can be appropriately chosen but it is
preferably from 0.01 to 10%, better still from 600 ppm to 2%, with
respect to the weight of the polymer to which the graft is
attached.
[0090] It is possible to graft, in all or part, the impact modifier
and to blend it with the HDPE. It is possible to graft the HDPE, in
all or part, and to blend it with the impact modifier. It is also
possible separately to graft, in all or part, the impact modifier,
to graft the HDPE, in all or part, and then to blend the two
grafted products. It is also possible to blend the impact modifier
with the HDPE and to graft, in all or part, the blend.
[0091] The proportion of functionalized HDPE and/or of
functionalized modifier with respect to the combined functionalized
or nonfunctionalized HDPE and functionalized or nonfunctionalized
impact modifier can be (by weight) between 0 and 70%,
advantageously between 5 and 60% and preferably between 20 and
60%.
[0092] According to one form of the invention, the HDPE is not
functionalized and the impact modifier is functionalized in all or
part.
[0093] The proportions of the blend of the third layer are
advantageously, the total being 100%: [0094] 55 to 80% of polyamide
(A), [0095] 10 to 20% of high density polyethylene (HDPE), [0096]
10 to 30% of impact modifier.
[0097] The blends of the third layer can be prepared by blending
the various constituents in the molten state in conventional
devices of the thermoplastic polymer industry.
[0098] The first layer can be composed of a layer of virgin HDPE
and of a layer of recycled polymers (also referred to as regrind
layer) originating from scrap material during the manufacture of
the transfer or storage devices or from these devices which have
failed specification, as is explained in the abovementioned prior
art. This layer of recycled polymers is situated on the side of the
tie layer. In the continuation of the text, these two layers will
be denoted for simplicity by the term "first layer". Functionalized
polyolefins can be added to this layer of recycled polymers in a
proportion which can, for example, be between 0.1 and 10% by
weight. These functionalized polyolefins are advantageously chosen
from the ties. Either HDPE or functionalized polyolefins or a blend
of the two can be added to this layer of recycled polymers.
[0099] The thickness of the first layer can be between 2 and 10 mm,
that of the second between 30 and 500 .mu.m and that of the third
between 500 .mu.m and 4 mm. As regards the tanks, the overall
thickness is usually between 3 and 10 mm.
[0100] As example of tie, mention may be made of functionalized
polyolefins. The tie between the first and the second layer and
that between the second and the third layer can be identical or
different. In the following descriptions of ties, the term
"polyethylene" denotes both homopolymers and copolymers.
[0101] As first tie example, mention may be made of a blend of a
polyethylene (C1) and of a polymer (C2) chosen from elastomers,
very low density polyethylenes and ethylene copolymers, the blend
(C1)+(C2) being cografted by an unsaturated carboxylic acid.
[0102] According to an alternative form, mention may be made of a
blend (i) of a polymer (C2) chosen from elastomers, very low
density polyethylenes and ethylene copolymers, (C2) being grafted
by an unsaturated carboxylic acid, and (ii) of a polymer (C2)
chosen from elastomers, very low density polyethylenes and ethylene
copolymers.
[0103] As second tie example, mention may be made of the blends
comprising:
[0104] 5 to 30 parts of a polymer (D) itself comprising a blend of
a polyethylene (D1) with a density of between 0.910 and 0.940 and
of a polymer (D2) chosen from elastomers, very low density
polyethylenes and metallocene polyethylenes, the blend (D1)+(D2)
being cografted by an unsaturated carboxylic acid,
[0105] 95 to 70 parts of a polyethylene (E) with a density of
between 0.910 and 0.930,
[0106] the blend of (D) and (E) being such that: [0107] its density
is between 0.910 and 0.930, [0108] the content of grafted
unsaturated carboxylic acid is between 30 and 10 000 ppm, [0109]
the MFI (ASTM D 1238, 190.degree. C., 2.16 kg) is between 0.1 and 3
g/10 min, the MFI denoting the melt flow index.
[0110] The density of the tie is advantageously between 0.915 and
0.920. Advantageously, (D1) and (E) are LLDPEs; preferably, they
have the same comonomer. This comonomer can be chosen from
1-hexene, 1-octene and 1-butene.
[0111] As third tie example, mention may be made of the blends
comprising:
[0112] 5 to 30 parts of a polymer (F) itself comprising a blend of
a polyethylene (F1) with a density of between 0.935 and 0.980 and
of a polymer (F2) chosen from elastomers, very low density
polyethylenes and ethylene copolymers, the blend (F1)+(F2) being
cografted by an unsaturated carboxylic acid,
[0113] 95 to 70 parts of a polyethylene (G) with a density of
between 0.930 and 0.950,
[0114] the blend of (F) and (G) being such that: [0115] its density
is between 0.930 and 0.950 and advantageously between 0.930 and
0.940, [0116] the content of grafted unsaturated carboxylic acid is
between 30 and 10 000 ppm, [0117] the MFI (melt flow index),
measured according to ASTM D 1238 at 190.degree. C. and 2.16 kg, is
between 5 and 100.
[0118] As fourth tie example, mention may be made of polyethylene
grafted by maleic anhydride having an MFI of 0.1 to 3 and a density
of between 0.920 and 0.930 and which comprises 2 to 40% by weight
of materials which are insoluble in n-decane at 90.degree. C. In
order to determine the materials which are insoluble in n-decane,
the grafted polyethylene is dissolved in n-decane at 140.degree.
C., is cooled to 90.degree. C. and products precipitate; it is then
filtered and the level of insoluble materials is the percentage by
weight which precipitates and is collected by filtration at
90.degree. C. If the level is between 2 and 40%, the tie has good
resistance to petrol.
[0119] Advantageously, the grafted polyethylene is diluted in an
ungrafted polyethylene such that the tie is a blend of 2 to 30
parts of a grafted polyethylene with a density of between 0.930 and
0.980 and of 70 to 98 parts of an ungrafted polyethylene with a
density of between 0.910 and 0.940, preferably 0.915 and 0.935.
[0120] As fifth tie example, mention may be made of the blends
comprising: [0121] 50 to 100 parts of a polyethylene (J) homo- or
copolymer with a density of greater than or equal to 0.9, [0122] 0
to 50 parts of a polymer (K) chosen from (K1) polypropylene homo-
or copolymer, (K2) poly(1-butene) homo- or copolymer and (K3)
polystyrene homo- or copolymer, [0123] the amount of (J)+(K) being
100 parts, [0124] the blend of (J) and (K) being grafted by at
least 0.5% by weight of a functional monomer, [0125] this grafted
blend being itself diluted in at least one polyethylene homo- or
copolymer (L) or in at least one polymer with an elastomeric nature
(M) or in a blend of (L) and (M).
[0126] According to one form of the invention, (J) is an LLDPE with
a density of 0.910 to 0.930, the comonomer having from 4 to 8
carbon atoms. According to another form of the invention, (K) is an
HDPE, advantageously with a density of at least 0.945 and
preferably of 0.950 to 0.980.
[0127] Advantageously, the functional monomer is maleic anhydride
and its content is from 1 to 5% by weight of (J)+(K).
[0128] Advantageously, (L) is an LLDPE, the comonomer of which has
from 4 to 8 carbon atoms, and its density is preferably at least
0.9 and preferably 0.910 to 0.930.
[0129] Advantageously, the amount of (L) or (M) or (L)+(M) is from
97 to 75 parts per 3 to 25 parts of (J)+(K), the amount of
(J)+(K)+(L)+(M) being 100 parts.
[0130] As sixth tie example, mention may be made of the blends
composed of a polyethylene of HDPE, LLDPE, VLDPE or LDPE type, 5 to
35% of a grafted metallocene polyethylene and 0 to 35% of an
elastomer, the total being 100%.
[0131] As seventh tie example, mention may be made of the blends
comprising:
[0132] at least one polyethylene or one ethylene copolymer,
[0133] at least one polymer chosen from polypropylene or a
propylene copolymer, poly(1-butene) homo- or copolymer, or
polystyrene homo- or copolymer, and preferably polypropylene,
[0134] this blend being grafted by a functional monomer and this
grafted blend being itself optionally diluted in at least one
polyolefin or in at least one polymer with an elastomeric nature or
in their blend. In the preceding blend which is grafted, the
polyethylene advantageously represents at least 50% of this blend
and preferably 60 to 90% by weight.
[0135] Advantageously, the functional monomer is chosen from
carboxylic acids and their derivatives, acid chlorides,
isocyanates, oxazolines, epoxides, amines or hydroxides and
preferably unsaturated dicarboxylic acid anhydrides.
[0136] As eighth tie example, mention may be made of the blends
comprising:
[0137] at least one LLDPE or VLDPE polyethylene,
[0138] at least one ethylene-based elastomer chosen from
ethylene/propylene copolymers and ethylene/butene copolymers,
[0139] this blend of polyethylene and of elastomer being grafted by
an unsaturated carboxylic acid or a functional derivative of this
acid,
[0140] this cografted blend being optionally diluted in a polymer
chosen from polyethylene homo- or copolymers and styrene block
copolymers,
[0141] the tie having [0142] (a) an ethylene content which is not
less than 70 mol %, [0143] (b) a content of carboxylic acid or of
its derivative of 0.01 to 10% by weight of the tie, and [0144] (c)
an MFI.sub.10/MFI.sub.2 ratio of 5 to 20, where MFI.sub.2 is the
melt flow index at 190.degree. C. under a load of 2.16 kg, measured
according to ASTM D1238, and MFI.sub.10 is the melt flow index at
190.degree. C. under a load of 10 kg, according to ASTM D1238.
[0145] The various layers of the structure of the invention,
including the tie layers, can additionally comprise at least one
additive chosen from: [0146] fillers (inorganic, flame-retardant,
conductive, and the like), [0147] nanofillers, such as, for
example, nanoclays, [0148] nanocomposites, [0149] fibres, [0150]
dyes, [0151] pigments, [0152] optical brighteners, [0153]
antioxidants, [0154] nucleating agents, [0155] UV stabilizers.
EXAMPLES
[0155] Polymers used:
[0156] PA A1: Terpolymer of caprolactam (L6), adipic acid (AA) and
hexamethylenediamine (HMDA) possessing an L6/[AA+HMDA] ratio by
mass of 85/15 and a "viscosity number" of 186 according to Standard
ISO 307.
[0157] PA A2: Copolymer of caprolactam and of lauryllactam
possessing a monomer composition by weight of 70/30 and an
intrinsic viscosity (measured at 20.degree. C. for a concentration
of 0.5 g per 100 ml of meta-cresol) of 1.3 dl/g.
[0158] PA A3: Copolymer of caprolactam and of lauryllactam
possessing a melting point of 190.degree. C. and a melt flow index
of 120 according to Standard ISO 1133, measured under the
conditions: 275.degree. C. under a load of 5 kg.
[0159] PA A4: Lauryllactam homopolymer possessing an intrinsic
viscosity (measured at 20.degree. C. for a concentration of 0.5 g
per 100 ml of meta-cresol) of 1.55 to 1.74 dl/g.
[0160] PA A5: 11-Aminoundecanoic acid homopolymer possessing an
intrinsic viscosity (measured at 20.degree. C. for a concentration
of 0.5 g per 100 ml of meta-cresol) of 1.35 to 1.52 dl/g.
[0161] PA A6 (10.10): Equimolar copolymer of sebacic acid (SA) and
of decanediamine (DA) possessing an intrinsic viscosity (measured
at 20.degree. C. for a concentration of 0.5 g per 100 ml of
meta-cresol) of 1.4 dl/g.
[0162] PA A7 (MXD.10): Equimolar copolymer of meta-xylylenediamine
(MXD) and of sebacic acid (SA) possessing an intrinsic viscosity
(measured at 20.degree. C. for a concentration of 0.5 g per 100 ml
of meta-cresol) of 1.4 dl/g.
[0163] PA A8 (MXD.12): Equimolar copolymer of meta-xylylenediamine
(MXD) and of dodecanedioic acid (DDA) possessing an intrinsic
viscosity (measured at 20.degree. C. for a concentration of 0.5 g
per 100 ml of meta-cresol) of 1.4 dl/g.
[0164] PE 1: Polyethylene possessing a density of 0.952 according
to Standard ISO 1183 and a melt flow index of 23 according to
Standard ISO 1133, measured under the conditions: 190.degree. C.
under a load of 2.16 kg.
[0165] PE 2: Polyethylene having a density of 0.949 according to
Standard ISO 1183 and a melt flow index of 8 g/10 min according to
Standard ISO 1133, measured under the conditions: 190.degree. C.
under a load of 2.16 kg.
[0166] P1: Terpolymer of ethylene, of propylene and of diene
monomer possessing a density of 0.89 and a Mooney viscosity (ML,
1+4, 125.degree. C.) of 30 and grafted by maleic anhydride at a
level of 1%.
[0167] P2: Terpolymer of ethylene, of propylene and of diene
monomer possessing a Mooney viscosity of 30 under the conditions ML
(1+4) 100.degree. C.
[0168] EVOH: Copolymer of ethylene and of p2yl alcohol possessing
an ethylene fraction by weight of 29% and a melt flow index of 3.2,
measured according to Standard ISO 1133 under the following
conditions: 210.degree. C. under a load of 2.16 kg.
[0169] T1 (Orevac): Polyethylene grafted by 3000 ppm of maleic
anhydride and possessing a melt flow index of 1, measured according
to Standard ASTM 1238 under the following conditions: 190.degree.
C. under a load of 2.16 kg.
[0170] Alloy 1: Compatibilized blend of PA and of PP possessing an
M.p. of 255.degree. C. and a melt flow index of 15, measured
according to Standard ISO 1133 under the following conditions:
275.degree. C. under a load of 2.16 kg, sold by the Applicant
Company under the reference Orgalloy.RTM. RS6600.
[0171] Alloy 2: Compatibilized blend of PA and of PE possessing an
M.p. of 225.degree. C. but a conversion temperature of 250.degree.
C. and a melt flow index of 2, measured according to Standard ISO
1133 under the following conditions: 235.degree. C. under a load of
2.16 kg, sold by the Applicant Company under the reference
Orgalloy.RTM. LE 6000.
[0172] Alloy 3: Compatibilized blend of PA and of PE possessing an
M.p. of 195.degree. C. and a melt flow index of 3, measured
according to Standard ISO 1133 under the following conditions:
235.degree. C. under a load of 2.16 kg, sold by the Applicant
Company under reference Orgalloy.RTM. LEC601.
Preparation of the alloys of polyamide and of polyolefin:
[0173] The alloys of polyamide and of polyolefin are prepared using
a corotating twin-screw extruder of Werner & Pfleiderer ZSK 40
type (diameter=40 mm, L=40D).
Preparation of multilayer hollow bodies by coextrusion
blow-moulding:
[0174] Multilayer bottles are prepared using a Bekum coextrusion
blow-moulding line equipped with 5 extruders, the barrels of which
are regulated at 220.degree. C., unless otherwise mentioned. The
blow-moulded structures are of two types: [0175] four-layer
structures described as follows, from the inside outwards: [0176]
1. Alloy of polyamide and of polyolefin: Thickness: 30% of the
overall thickness (extruder 1) [0177] 2. EVOH: Thickness: 5% of the
overall thickness (extruder 2) [0178] 3. T1: Thickness: 5% of the
overall thickness (extruder 3) [0179] 4. PE2: Thickness: 60% of the
overall thickness (extruder 4) [0180] The overall thickness is 3 mm
on average. five-layer structures described as follows, from the
inside outwards: [0181] 1. Alloy of polyamide and of polyolefin:
Thickness: 30% of the overall thickness (extruder 1) [0182] 2. Ti:
Thickness: 5% of the overall thickness (extruder 5) [0183] 3. EVOH:
Thickness: 5% of the overall thickness (extruder 2) [0184] 4. T1:
Thickness: 5% of the overall thickness (extruder 3) [0185] 5. PE2:
Thickness: 55% of the overall thickness (extruder 4) [0186] The
overall thickness is 3 mm on average.
[0187] Impact strength of the bottles:
[0188] The blow-moulded bottles, conditioned beforehand at
-40.degree. C., are tested on one of their flat surfaces with
regard to impact strength under the following conditions:
T=-40.degree. C. and impact speed=4.3 m/s.
[0189] The force-displacement curve resulting from this test makes
it possible to calculate the impact strength of the multilayer
bottle.
Results:
Examples 1 to 3
[0190] 3 four-layer bottles, the structures of which are collated
in the table below, were extruded blow-moulded on the Bekum
extrusion line. TABLE-US-00001 Example 1* Example 2** (comparative)
(comparative) Example 3 Alloy 1 Alloy 2 Alloy 3 EVOH EVOH EVOH T1
T1 T1 Structure PE2 PE2 PE2 Quality of the Lack of coextrusion Lack
of coextrusion Correct coextrusion *Extruder 1 is regulated at
280.degree. C. ** Extruder 1 is regulated at 250.degree. C.
[0191] These experiments demonstrate that it is advisable to use a
polyamide possessing a conversion temperature of less than
230.degree. C. in order to provide correct processing by
coextrusion blow-moulding.
Examples 4 to 7
[0192] The alloys of polyamide and of polyolefin collated in the
tables below were prepared: TABLE-US-00002 Composition: Alloy 4
Alloy 5 Alloy 6 Alloy 7 PA A1 50 50 PA A2 71 60 PEl 25 15 15 15 P1
4 35 29 19 P2 6 6
Examples 8 to 11
[0193] 4 five-layer bottles, the structures of which are collated
in the table below, were extruded blow-moulded on the Bekum
extrusion line. TABLE-US-00003 Example 8 Example 9 Example 10
Example 11 Alloy 4 Alloy 5 Alloy 6 Alloy 7 T1 T1 T1 T1 EVOH EVOH
EVOH EVOH T1 T1 T1 T1 Structure PE2 PE2 PE2 PE2 Quality of the
Correct Lack of Lack of Correct coextrusion coextrusion coextrusion
Impact strength No* Yes** Yes Yes *"No" means that the value of the
impact strength measured is less than 50 J **"Yes" means that the
value of the impact strength measured exceeds 50 J
Examples 12 to 17
[0194] The alloys of polyamide and of polyolefin collated in the
tables below were prepared: TABLE-US-00004 Alloy Alloy Alloy Alloy
Alloy Alloy Comp. 12 13 14 15 16 17 PA A3 PA A4 60 PA A5 60 PA A6
60 PA A7 60 PA A8 60 PE 1 60 P 1 15 15 15 15 15 15 P 2 19 19 19 19
19 19 6 6 6 6 6 6
Examples 18 to 22
[0195] 6 five-layer bottles, the structures of which are collated
in the table below, were extruded blow-moulded on the Bekum
extrusion line. TABLE-US-00005 Example 17 Example 18 Example 19
Example 20 Example 21 Example 22 Alloy 12 Alloy 13 Alloy 14 Alloy
15 Alloy 16 Alloy 17 T1 T1 T1 T1 T1 T1 EVOH EVOH EVOH EVOH EVOH
EVOH T1 T1 T1 T1 T1 T1 Structure PE2 PE2 PE2 PE2 PE2 PE2 Quality of
the Correct Correct Correct Correct Correct Correct coextrusion
Impact Yes* Yes Yes Yes Yes Yes strength *"Yes" means that the
value of the impact strength measured exceeds 50 J
* * * * *