U.S. patent application number 16/260461 was filed with the patent office on 2019-05-23 for peba for direct adhesion to tpe.
The applicant listed for this patent is Arkema France. Invention is credited to Yves Deyrail, Rene-Paul Eustache, Quentin Pineau, Martin POUZET, Mathieu Sabard, Inci Turan-Altuntas, Atsushi YOSHITAKE.
Application Number | 20190153277 16/260461 |
Document ID | / |
Family ID | 53879691 |
Filed Date | 2019-05-23 |
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United States Patent
Application |
20190153277 |
Kind Code |
A1 |
Eustache; Rene-Paul ; et
al. |
May 23, 2019 |
PEBA FOR DIRECT ADHESION TO TPE
Abstract
The invention relates to a copolymer having polyamide PA blocks
and polyether PE blocks, in which PA is of diamine.diacid X.Y type;
X, the number of carbons of the diamine, is within the range from 6
to 14, and Y, the number of carbons of the diacid, is within the
range from 6 to 18. The invention also relates to the use of the
said copolymer in a process of direct adhesion between two TPE
materials for increasing the peel strength between these
materials.
Inventors: |
Eustache; Rene-Paul;
(Combon, FR) ; Sabard; Mathieu; (Serquigny,
FR) ; Deyrail; Yves; (Aviron, FR) ; Pineau;
Quentin; (Evreux, FR) ; Turan-Altuntas; Inci;
(Val De Reuil, FR) ; POUZET; Martin; (Mumbai,
IN) ; YOSHITAKE; Atsushi; (Kyoto, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Arkema France |
Colombes |
|
FR |
|
|
Family ID: |
53879691 |
Appl. No.: |
16/260461 |
Filed: |
January 29, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15192276 |
Jun 24, 2016 |
10246618 |
|
|
16260461 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L 77/06 20130101;
B32B 27/285 20130101; C08G 2170/20 20130101; B32B 2377/00 20130101;
C08G 81/00 20130101; B32B 7/12 20130101; C08G 2170/90 20130101;
B32B 2371/00 20130101; B32B 37/06 20130101; B32B 2437/02 20130101;
C09J 5/06 20130101; B32B 27/08 20130101; C09J 2475/006 20130101;
B32B 27/34 20130101; C09J 187/005 20130101; C08G 69/40
20130101 |
International
Class: |
C09J 187/00 20060101
C09J187/00; C08L 77/06 20060101 C08L077/06; B32B 7/12 20060101
B32B007/12; C08G 69/40 20060101 C08G069/40; C09J 5/06 20060101
C09J005/06; C08G 81/00 20060101 C08G081/00; B32B 37/06 20060101
B32B037/06; B32B 27/34 20060101 B32B027/34; B32B 27/28 20060101
B32B027/28; B32B 27/08 20060101 B32B027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 26, 2015 |
FR |
15 56000 |
Claims
1. Copolymer having polyamide PA blocks and polyether PE blocks, in
which PA is of X.Y type; X, the number of carbons of the diamine,
is within the range from 6 to 14, and Y, the number of carbons of
the diacid, is within the range from 6 to 18.
2. Copolymer according to claim 1, in which X is chosen from 6 or
10 and Y is chosen from 10 or 12.
3. Copolymer according to claim 1, in which PE is chosen from PTMG,
PPG, PO3G and/or PEG.
4. Copolymer according to claim 1, in which said copolymer
comprises from 51 to 90% by weight of polyamide blocks and
respectively from 49 to 10% by weight, of polyether blocks, with
respect to the total weight of copolymer.
5. Copolymer according to claim 1, in which the number-average
molecular weight (Mn) of the PA blocks is within the range from 500
to 10,000.
6. Copolymer according to claim 1, in which the number-average
molecular weight (Mn) of the PE blocks is within the range from 400
to 1,000.
7. Copolymer according to claim 2, wherein PA X.Y is PA 6.10 or PA
6.12.
8. Copolymer according to claim 3, in which PE is chosen from PTMG,
PPG and/or PO3G.
9. Copolymer according to claim 4, in which said copolymer
comprises from 60 to 90% by weight of polyamide blocks and
respectively from 40 to 10% by weight and of polyether blocks, with
respect to the total weight of copolymer.
10. Copolymer according to claim 9, in which said copolymer
comprises from 65 to 85% by weight of polyamide blocks and
respectively from 35 to 15% by weight and of polyether blocks, with
respect to the total weight of copolymer.
11. Copolymer according to claim 5, in which the number-average
molecular weight (Mn) of the PA blocks is within the range from
1,000 to 10,000.
12. Copolymer according to claim 11, in which the number-average
molecular weight (Mn) of the PA blocks is within the range from
2000 to 9000.
13. Copolymer according to claim 12, in which the number-average
molecular weight (Mn) of the PA blocks is within the range from
2000 to 6000.
14. Copolymer according to claim 13, in which the number-average
molecular weight (Mn) of the PA blocks is within the range from
2000 to 3000.
15. Copolymer according to claim 14, in which the number-average
molecular weight (Mn) of the PA blocks is within the range from
2500 to 3000.
16. Copolymer according to claim 6, in which the number-average
molecular weight (Mn) of the PE blocks is within the range from 500
to 1000.
17. Copolymer according to claim 15, in which the number-average
molecular weight (Mn) of the PE blocks is within the range from 600
to 700.
18. Copolymer according to claim 16, in which the number-average
molecular weight (Mn) of the PE blocks is within the range from 600
to 650.
Description
REFERENCE TO PRIOR APPLICATIONS
[0001] This application is a division of copending U.S. application
Ser. No. 15/192,276, filed Jun. 24, 2016, which claims benefit,
under U.S.C. .sctn. 119(a) of French National Application Number
15,56000, filed Jun. 26, 2015. Each of the foregoing applications
is incorporated herein by reference in its entirety for all
purposes.
FIELD OF THE INVENTION
[0002] The present invention relates to a novel copolymer having
polyamide PA blocks and polyether PE blocks (abbreviated to PEBA)
which is particularly well suited to the process of direct adhesion
to a substrate based on thermoplastic elastomer (abbreviated to
TPE), in particular to TPU.
[0003] The present invention also relates to the assembling by
direct adhesion of a first substrate based on PEBA according to the
invention (C1) and of a second substrate (C2), it being possible
for the substrates to be of the same nature or of different nature.
In addition, the present invention relates to a laminated product
formed by the assembling of such substrates by direct adhesion.
[0004] The present invention relates in particular to a process for
the manufacture of such a laminate and to its use in the footwear
industry, in particular for the manufacture of soles and very
particularly of sports shoe soles.
TECHNICAL BACKGROUND
[0005] One of the main areas of expertise of the footwear industry
is good control of the adhesive bonding techniques intended to
assemble materials of different chemical natures and with different
mechanical properties. This expertise is particularly important in
the field of sports shoes, where the materials used, in particular
for the manufacture of the soles, are frequently novel materials.
This requirement is magnified by the search for performance
generally related to the sports shoe.
[0006] During the last decade, materials based on TPE, such as the
PEBA materials sold by Arkema under the Pebax.RTM. trademark, have
gradually become established in the field of top of the range
footwear, in particular sports shoes, by virtue of their mechanical
properties and in particular their exceptional resilience property.
Specifically, PEBAs can advantageously be used in sports shoes as
sole of "semi-rigid" type (football, baseball, and the like) or
flexible type (jogging), making it possible to directly produce the
internal sole (damping) and/or the external sole (abrasion
resistance-stiffness).
[0007] The assembling of TPE on TPEs of the same nature or with
different compositions is obtained by moulding or extruding,
possible cutting up of the components and then adhesively bonding
and pressing these components, or also by direct adhesion of these
TPEs.
[0008] The term "direct adhesion process" is understood to mean an
adhesion process without contribution of binder, in particular
contribution of adhesive. In comparison with conventional adhesive
bonding processes involving a multitude of complicated stages
generally using adhesives based on organic solvents, direct
adhesion processes are more ecological and non-polluting.
[0009] Mention may be made, as examples of direct adhesion process,
of: overmoulding, hot pressing, coextrusion, thermoforming,
two-material injection moulding, co-injection moulding and any
other possible adhesion method using one or more of the
conventional methods, such as injection moulding, extrusion
moulding and/or blow moulding.
[0010] This cohesion between the materials is rendered possible by
the adhesive properties which the polymers possess in the molten
state. For example, the patent document EP197845 describes a
process for assembling surfaces by application of a PEBA seal and
melting of its surface layer. The patent document EP179700
describes an adhesive composition comprising a PEBA and its use as
pressure-sensitive adhesive. The patent document EP0679119
describes a two-layer object comprising a lightened thermoplastic
elastomer of polyetheramide type which adheres by itself to a
non-lightened thermoplastic which can be chosen from
polyetheramides, polyetheresters or polyurethanes.
[0011] The overmoulding technique consists of the injection of
substance over an insert placed at the bottom of the mould. The
cohesion of the two materials is obtained by the hot melt and
compatibility properties of the overmoulded substance and of the
insert. PEBAs are very well suited to this overmoulding technique
as they have a broad plasticizing range, making it possible to
optimize the adhesion of the substance and of the inserts and to
avoid the use of adhesive.
[0012] Unfortunately, the levels of adhesion, expressed by the peel
strength, of the TPE-based substrates of the systems of the prior
art obtained by direct adhesion are far from being optimal. Thus,
with some of the PEBA substrates with a Shore D hardness of 60 to
65 on average (for example Pebax.RTM. 6333), at best weak peel
strengths of 3 kg/cm are obtained. In point of fact, footwear
manufacturers require, for some applications, a peel strength of at
least 5, preferably of at least 8, indeed even of at least 10
kg/cm.
[0013] It is thus an aim of the present invention to provide a PEBA
with properties of improved direct adhesion to TPE substrates and
in particular to TPU.
[0014] Another aim of the present invention is to provide a
laminate comprising at least one PEBA-based substrate and also a
process for the manufacture of such a laminate by direct adhesion,
the laminate having to exhibit a peel strength of greater than 3
kg/cm, preferably of at least 5 kg/cm, preferably of at least 8
kg/cm, indeed even of at least 10 kg/cm, measured according to
Standard ISO 11339.
[0015] A further aim of the present invention is to increase the
level of adhesion of TPE materials without detrimentally affecting
their mechanical properties.
[0016] The Applicant Company has now developed a novel type of PEBA
which exhibits a markedly better direct adhesion to TPE than that
of the existing PEBAs, with a peel strength of greater than 10
kg/cm, while retaining excellent mechanical properties, such as
good liveliness, a low density and low cold stiffening.
SUMMARY OF THE INVENTION
[0017] The invention relates first to a copolymer having polyamide
PA blocks and polyether PE blocks, in which PA is of X.Y type; X,
the number of carbons of the diamine, is within the range from 4 to
14, preferably from 6 to 14, and preferably from 6 to 12, and Y,
the number of carbons of the diacid, is within the range from 6 to
18, preferably from 6 to 12 and preferably from 10 to 12.
Advantageously, X is chosen from 6 or 10, and Y is chosen from 10
or 12; preferably, PA X.Y is PA 6.10 or PA 6.12, preferably PA
6.10. Advantageously, PE is chosen from PTMG, PPG, PO3G and/or PEG
and is preferably chosen from PTMG, PPG and/or PO3G. Preferably,
the copolymer according to the invention is chosen from the PEBA
PA6.10-PTMG or PA6.12-PTMG, preferably PA6.10-PTMG. Advantageously,
the said copolymer comprises from 51 to 90% by weight, preferably
from 60 to 90% by weight and preferably from 65 to 85% by weight of
polyamide blocks and respectively from 49 to 10% by weight,
preferably from 40 to 10% by weight and preferably from 35 to 15%
by weight of polyether blocks, with respect to the total weight of
copolymer. Advantageously, the number-average molecular weight (Mn)
of the PA blocks is within the range from 500 to 10 000, preferably
from 1000 to 10 000, preferably from 2000 to 9000, preferably from
2000 to 6000, preferably from 2000 to 3000 and preferably from 2500
to 3000. Advantageously, the number-average molecular weight (Mn)
of the PE blocks is within the range from 400 to 1000, preferably
from 500 to 1000, preferably from 600 to 700, indeed even from 600
to 650. Another subject-matter of the present invention is the use
of a PEBA in a process of direct adhesion between two TPE materials
for increasing the peel strength between these materials,
characterized in that the PEBA is a copolymer according to the
invention described above. A subject-matter of the present
invention is in particular a composition based on copolymer
according to the invention described above, the composition being
characterized in that it comprises: [0018] from 51 to 99.9% by
weight of the said copolymer, [0019] from 0.1 to 49% by weight of
at least one other component chosen from: PEBAs with a different
composition and/or with a different flexural modulus from that of
the copolymer, PAs, POFs, COPEs, TPUs, reinforcing fillers and/or
fibres, in particular of glass or of carbon, colourants, UV
absorbers, antioxidants, in particular phenolic antioxidants or
antioxidants based on phosphorus or based on sulphur, light
stabilizers of hindered amine or HALS type, and their mixtures. A
further subject-matter of the present invention is a process for
direct adhesion of a copolymer material (C1) according to the
invention with a TPE copolymer material (C2), C2 being of identical
composition to and having the same flexural modulus as C1, or else
being of identical composition to but having a different flexural
modulus from C1, or else C2 is a TPE material chosen from: PEBAs of
different compositions from that of the said copolymer C1, COPEs
and/or TPUs, the process according to the invention being
characterized in that the assembling is carried out by a process
comprising the heating of at least one of the two copolymer
materials C1 and/or C2, so as to cause one material to adhere to
the other. According to an advantageous embodiment of the process
of the invention, the material C1 is melted or softened under
heating and the molten material C1 is brought into contact with at
least a portion of the material C2 of the series of the
thermoplastic polyurethanes TPUs in order to cause the two
materials to adhere. According to a second advantageous embodiment
of the process of the invention, the material C2 of the series of
the thermoplastic polyurethanes TPUs is melted or softened under
heating and the molten material C2 is brought into contact with at
least a portion of the material C1 in order to cause the two
materials to adhere. According to a third advantageous embodiment
of the process of the invention, the material C1 and the material
C2 of the series of the TPUs are independently melted or softened
under heating and the molten material C1 is brought into contact
with at least a portion of the molten material C2 in order to cause
the two materials to adhere. Advantageously, in the assembling in
process according to the invention, the material C1 and the
material C2 are assembled by a direct adhesion process chosen from:
overmoulding, hot pressing, coextrusion, thermoforming, injection
moulding, extrusion moulding, blow moulding and their mixtures,
preferably by overmoulding one material over the other, preferably
by overmoulding the copolymer according to the invention over a TPE
and preferably by overmoulding the copolymer over a TPU.
Advantageously, the assembling temperature of the direct adhesion
process according to the invention is within the range from 220 to
300.degree. C., preferably from 250 to 290.degree. C. and
preferably from 270 to 290.degree. C. Another subject-matter of the
present invention is a composite article comprising at least two
polymer materials which adhere directly to one another, one with a
composition in accordance with the invention described above and
the other made of TPE chosen from identical PEBA (with a flexural
modulus different from that of the copolymer), PEBA of composition
different from that of the said copolymer, COPE and/or TPU. Another
subject-matter of the present invention is the use of an article
according to the invention in the manufacture of sports equipment,
of a component of footwear, in particular of sports shoe, shoe
sole, in particular crampon, component of a ski, in particular of a
ski boot or of a ski shell, of a medical device, of a transmission
belt, as antistatic additive, as waterproof-breathable film, as
support for active molecules, as colouring agent, as welding agent,
as decorative element and/or as additive for polyamide.
[0020] The present invention makes it possible to overcome the
disadvantages of the state of the art. It more particularly
provides a PEBA capable of adhering directly to TPU, by heating,
without decomposing the materials to be assembled, while
contributing good liveliness, a low density and low cold stiffening
to the laminated material thus obtained.
[0021] This is accomplished by virtue of the use of the specific
PEBA according to the invention. This result is surprising in so
far as polycondensed thermoplastic elastomer polymers of high
hardness (60 to 65 Shore D) are generally difficult to assemble by
direct adhesion in a way which is both effective and lasting to
TPU.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1: is a plot of the cold stiffening as measured by the
change in the E' modulus (MPa) as a function of temperature T or by
the change in the E'(T)/E'(23.degree. C.) ratio as a function of
the temperature over the range -40.degree. C. to +23.degree. C.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0023] In the present description, it is specified that, when
reference is made to intervals, the expressions of the "ranging
from . . . to" or "comprising from . . . to" type include the
limits of the interval. Conversely, the expressions of the "of
between . . . and . . . " type exclude the limits of the
interval.
Unless otherwise mentioned, the percentages expressed are
percentages by weight. Unless otherwise mentioned, the parameters
to which reference is made are measured at atmospheric pressure and
ambient temperature (20-25.degree. C., generally 23.degree.
C.).
[0024] The invention is now described in more detail and without
implied limitation in the description which follows.
[0025] The term "thermoplastic elastomer polymer", abbreviated to
"TPE", denotes a polymer which constitutes a multiphase material
exhibiting at least two transitions, namely a first transition at a
temperature T1 (this is generally the glass transition temperature)
and a second transition at a temperature T2 greater than T1 (this
is generally the melting point). The material is rigid at a
temperature below T1, has an elastic behaviour between T1 and T2
and is molten above T2. Such a specific polymer combines the
elastic behaviour of materials of rubber type with the ability for
conversion of thermoplastics.
[0026] The PEBA According to the Invention Used as Material or
Substrate C1
[0027] A subject-matter of the invention is a specific copolymer
having polyamide PA blocks and polyether PE blocks (PEBA) selected
for its ability to directly adhere to another TPE by simple
heating.
[0028] This PEBA according to the invention has the essential
characteristic of comprising polyamide PA blocks of X.Y type, in
which X, the number of carbons of the diamine, is within the range
from 4 to 14, preferably from 6 to 14, and Y, the number of carbons
of the diacid, is within the range from 6 to 18.
[0029] X is preferably chosen from 6 or 10 and Y is chosen from 10
or 12; preferably, the PA X.Y is PA 6.10 or PA 6.12, preferably PA
6.10.
[0030] Advantageously, the number-average molecular weight (Mn) of
the PA blocks is within the range from 500 to 10 000, preferably
from 1000 to 10 000, preferably from 2000 to 9000, preferably from
2000 to 6000, preferably from 2000 to 3000 and preferably from 2500
to 3000.
[0031] As regards the PE blocks of the PEBA according to the
invention, PE is chosen from PTMG, PPG, PO3G and/or PEG and is
preferably chosen from PTMG, PPG and/or PO3G. Advantageously, the
number-average molecular weight (Mn) of the PE blocks is within the
range from 400 to 1000, preferably from 500 to 1000, preferably
from 600 to 700, indeed even from 600 to 650.
[0032] Advantageously, the said copolymer comprises from 51 to 90%
by weight, preferably from 60 to 90% by weight and preferably from
65 to 85% by weight of polyamide blocks and respectively from 49 to
10% by weight, preferably from 40 to 10% by weight and preferably
from 35 to 15% by weight of polyether blocks, with regard to the
total weight of the copolymer.
[0033] Other TPEs Used as Material or Substrate C2
[0034] The other TPEs used in the context of the invention can be
chosen from the group consisting of copolyether-block-amides,
copolyether-block-urethanes, copolyester-block-urethanes and
copolyether-block-esters, and combinations of these. The general
definition of each of these TPEs is restated below.
[0035] Copolyether-block-amides, also known as copolymers having
polyether blocks and polyamide blocks, or "PEBA" as an
abbreviation, result from the polycondensation of polyamide blocks
having reactive ends with polyether blocks having reactive ends,
such as, inter alia:
[0036] 1) polyamide blocks having diamine chain ends with
polyoxyalkylene blocks having dicarboxylic chain ends;
[0037] 2) polyamide blocks having dicarboxylic chain ends with
polyoxyalkylene blocks having diamine chain ends, obtained by
cyanoethylation and hydrogenation of .alpha.,.omega.-dihydroxylated
aliphatic polyoxyalkylene blocks, known as polyether diols;
[0038] 3) polyamide blocks having dicarboxylic chain ends with
polyether diols, the products obtained being, in this particular
case, polyetheresteramides.
[0039] The polyamide blocks having dicarboxylic chain ends
originate, for example, from the condensation of polyamide
precursors in the presence of a chain-limiting dicarboxylic acid.
The polyamide blocks having diamine chain ends originate, for
example, from the condensation of polyamide precursors in the
presence of a chain-limiting diamine.
[0040] The number-average molar mass Mn of the polyamide blocks is
between 400 and 20 000 g/mol and preferably between 500 and 10 000
g/mol.
[0041] The polymers having polyamide blocks and polyether blocks
can also comprise randomly distributed units.
[0042] Use may advantageously be made of three types of polyamide
blocks.
[0043] According to a first type, the polyamide blocks originate
from the condensation of a dicarboxylic acid, in particular those
having from 4 to 20 carbon atoms, preferably those having from 6 to
18 carbon atoms, and of an aliphatic or aromatic diamine, in
particular those having from 2 to 20 carbon atoms, preferably those
having from 6 to 14 carbon atoms.
[0044] Mention may be made, as examples of dicarboxylic acids, of
1,4-cyclohexanedicarboxylic acid, butanedioic acid, adipic acid,
azelaic acid, suberic acid, sebacic acid, dodecanedicarboxylic
acid, octadecanedicarboxylic acid, terephthalic acid, isophthalic
acid, but also dimerized fatty acids.
[0045] Mention may be made, as examples of diamines, of
tetramethylenediamine, hexamethylenediamine,
1,10-decamethylenediamine, dodecamethylenediamine,
trimethylhexamethylenediamine, isomers of
bis(4-aminocyclohexyl)methane (BACM),
bis(3-methyl-4-aminocyclohexyl)methane (BMACM), and
2,2-bis(3-methyl-4-amino-cyclohexyl)propane (BMACP), and
di(para-aminocyclohexyl)methane (PACM), and isophoronediamine
(IPDA), 2,6-bis(aminomethyl)norbornane (BAMN) and piperazine
(Pip).
[0046] For example, PA 4.12, PA 4.14, PA 4.18, PA 6.10, PA 6.12, PA
6.14, PA 6.18, PA 9.12, PA 10.10, PA 10.12, PA 10.14 and PA 10.18
blocks are available.
[0047] According to a second type, the polyamide blocks result from
the condensation of one or more .alpha.,.omega.-aminocarboxylic
acids and/or of one or more lactams having from 6 to 12 carbon
atoms in the presence of a dicarboxylic acid having from 4 to 12
carbon atoms or of a diamine. Mention may be made, as examples of
lactams, of caprolactam, oenantholactam and lauryllactam. Mention
may be made, as examples of .alpha.,.omega.-aminocarboxylic acids,
of aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic
acid and 12-aminododecanoic acid.
[0048] Advantageously, the polyamide blocks of the second type are
of polyamide 11, of polyamide 12 or of polyamide 6.
[0049] According to a third type, the polyamide blocks result from
the condensation of at least one .alpha.,.omega.-aminocarboxylic
acid (or one lactam), at least one diamine and at least one
dicarboxylic acid.
[0050] In this case, the polyamide PA blocks are prepared by
polycondensation: [0051] of the linear aliphatic or aromatic
diamine or diamines having X carbon atoms; [0052] of the
dicarboxylic acid or acids having Y carbon atoms; and [0053] of the
comonomer or comonomers {Z}, chosen from lactams and
.alpha.,.omega.-aminocarboxylic acids having Z carbon atoms and
equimolar mixtures of at least one diamine having X1 carbon atoms
and of at least one dicarboxylic acid having Y1 carbon atoms, (X1,
Y1) being different from (X, Y); [0054] said comonomer or
comonomers {Z} being introduced in a proportion by weight ranging
up to 50%, preferably up to 20% and more advantageously still up to
10%, with respect to the combined polyamide precursor monomers;
[0055] in the presence of a chain-limiting agent chosen from
dicarboxylic acids.
[0056] Use is advantageously made, as chain-limiting agent, of the
dicarboxylic acid having Y carbon atoms, which is introduced in
excess with respect to the stoichiometry of the diamine or
diamines.
[0057] According to an alternative form of this third type, the
polyamide blocks result from the condensation of at least two
.alpha.,.omega.-aminocarboxylic acids or of at least two lactams
having from 6 to 12 carbon atoms or of a lactam and of an
aminocarboxylic acid not having the same number of carbon atoms, in
the optional presence of a chain-limiting agent. Mention may be
made, as examples of aliphatic .alpha.,.omega.-aminocarboxylic
acids, of aminocaproic acid, 7-aminoheptanoic acid,
11-aminoundecanoic acid and 12-aminododecanoic acid. Mention may be
made, as examples of lactam, of caprolactam, oenantholactam and
lauryllactam. Mention may be made, as examples of aliphatic
diamines, of hexamethylenediamine, dodecamethylenediamine and
trimethylhexamethylenediamine. Mention may be made, as example of
cycloaliphatic diacids, of 1,4-cyclohexanedicarboxylic acid.
Mention may be made, as examples of aliphatic diacids, of
butanedioic acid, adipic acid, azelaic acid, suberic acid, sebacic
acid, dodecanedicarboxylic acid, dimerized fatty acids (these
dimerized fatty acids preferably have a dimer content of at least
98%; preferably, they are hydrogenated; they are sold under the
Pripol.RTM. trademark by Uniqema or under the Empol.RTM. trademark
by Henkel) and polyoxyalkylene-.alpha.,.omega.-diacids. Mention may
be made, as examples of aromatic diacids, of terephthalic acid (T)
and isophthalic acid (I). Mention may be made, as examples of
cycloaliphatic diamines, of the isomers of
bis(4-aminocyclohexyl)methane (BACM),
bis(3-methyl-4-aminocyclohexyl)methane (BMACM) and
2,2-bis(3-methyl-4-amino-cyclohexyl)propane (BMACP), and
di(para-aminocyclohexyl)methane (PACM). The other diamines commonly
used can be isophoronediamine (IPDA),
2,6-bis(amino-methyl)norbomane (BAMN) and piperazine.
[0058] Mention may be made, as examples of polyamide blocks of the
third type, of the following: [0059] 6.6/6, in which 6.6 denotes
hexamethylenediamine units condensed with adipic acid. 6 denotes
units resulting from the condensation of caprolactam. [0060]
6.6/6.10/11/12, in which 6.6 denotes hexamethylenediamine condensed
with adipic acid. 6.10 denotes hexamethylenediamine condensed with
sebacic acid. 11 denotes units resulting from the condensation of
aminoundecanoic acid. 12 denotes units resulting from the
condensation of lauryllactam.
[0061] The weight Mn of the polyether blocks is between 100 and
6000 g/mol and preferably between 200 and 3000 g/mol.
[0062] Preferably, the polymer comprises from 1 to 80% by weight of
polyether blocks and from 20 to 99% by weight of polyamide blocks,
preferably from 4 to 80% by weight of polyether blocks and from 20
to 96% by weight of polyamide blocks.
[0063] The polyether blocks consist of alkylene oxide units. These
units can, for example, be ethylene oxide units, propylene oxide
units or tetrahydrofuran units (which results in polytetramethylene
glycol sequences). Use is thus made of PEG (polyethylene glycol)
blocks, that is to say those consisting of ethylene oxide units,
PPG (polypropylene glycol) blocks, that is to say those consisting
of propylene oxide units, PO3G (polytrimethylene glycol) blocks,
that is to say those consisting of trimethylene ether units (such
copolymers with polytrimethylene ether blocks are described in the
document U.S. Pat. No. 6,590,065), and PTMG blocks, that is to say
those consisting of tetramethylene glycol units, also known as
polytetrahydrofuran blocks. The PEBA copolymers can comprise, in
their chain, several types of polyethers, it being possible for the
copolyethers to be block or random copolyethers.
[0064] Use may also be made of blocks obtained by oxyethylation of
bisphenols, such as, for example, bisphenol A. The latter products
are described in Patent EP 613 919.
[0065] The polyether blocks can also consist of ethoxylated primary
amines. Mention may be made, as examples of ethoxylated primary
amines, of the products of formula:
##STR00001##
[0066] in which m and n are between 1 and 20 and x is between 8 and
18. These products are available commercially under the
Noramox.RTM. tradename from CECA and under the Genamin.RTM.
tradename from Clariant.
[0067] The flexible polyether blocks can comprise polyoxyalkylene
blocks having NH.sub.2 chain ends, it being possible for such
blocks to be obtained by cyanoacetylation of
.alpha.,.omega.-dihydroxylated aliphatic polyoxyalkylene blocks,
known as polyether diols. More particularly, use may be made of
Jeffamines (for example Jeffamine.RTM. D400, D2000, ED 2003 or XTJ
542, commercial products from Huntsman, also described in patent
documents JP2004346274, JP2004352794 and EP 1 482 011).
[0068] The polyether diol blocks are either used as is and
copolycondensed with polyamide blocks having carboxylic ends, or
they are aminated in order to be converted into polyether diamines
and condensed with polyamide blocks having carboxylic ends. The
general method for the preparation in two stages of the PEBA
copolymers having ester bonds between the PA blocks and the PE
blocks is known and is described, for example, in French Patent FR
2 846 332. The general method for the preparation of the PEBA
copolymers of the invention having amide bonds between the PA
blocks and the PE blocks is known and is described, for example, in
European Patent EP 1 482 011. The polyether blocks can also be
mixed with polyamide precursors and a diacid chain-limiting agent
in order to produce polymers having polyamide blocks and polyether
blocks which have randomly distributed units (one-stage
process).
[0069] Of course, the designation PEBA in the present description
of the invention relates equally well to the Pebax.RTM. products
sold by Arkema, to the Vestamid.RTM. products sold by Evonik, to
the Grilamid.RTM. products sold by EMS, to the Kellaflex.RTM.
products sold by DSM or to any other PEBA from other suppliers.
[0070] Advantageously, the PEBA copolymers have PA blocks of PA 6,
of PA 11, of PA 12, of PA 6.12, of PA 6.6/6, of PA 10.10 and/or of
PA 6.14, preferably PA 11 and/or PA 12 blocks; and PE blocks of
PTMG, of PPG and/or of PO3G. The PEBAs based on PE blocks
predominantly composed of PEG are to be placed in the range of the
hydrophilic PEBAs. The PEBAs based on PE blocks predominantly
composed of PTMG are to be placed in the range of the hydrophobic
PEBAs.
[0071] Advantageously, the said PEBA used in the composition
according to the invention is obtained, at least partially, from
biobased starting materials.
[0072] The term "starting materials of renewable origin" or
"biobased starting materials" is understood to mean substances
which comprise biobased carbon or carbon of renewable origin.
Specifically, unlike substances resulting from fossil materials,
substances composed of renewable starting materials comprise
.sup.14C. The "content of carbon of renewable origin" or "content
of biobased carbon" is determined by the application of Standards
ASTM D 6866 (ASTM D 6866-06) and ASTM D 7026 (ASTM D 7026-04). By
way of example, the PEBAs based on polyamide 11 originate at least
in part from biobased starting materials and exhibit a content of
biobased carbon of at least 1%, which corresponds to a
.sup.12C/.sup.14C isotopic ratio of at least 1.2.times.10.sup.-14.
Preferably, the PEBAs according to the invention comprise at least
50% by weight of biobased carbon with respect to the total weight
of carbon, which corresponds to a .sup.12C/.sup.14C isotopic ratio
of at least 0.6.times.10.sup.-12. This content is advantageously
higher, in particular up to 100%, which corresponds to a
.sup.12C/.sup.14C isotopic ratio of 1.2.times.10.sup.-12, in the
case, for example, of PEBA having PA 11 blocks and PE blocks
comprising PO3G, PTMG and/or PPG resulting from starting materials
of renewable origin.
[0073] Use may also be made, as TPE for the material C2, of a
copolyether-block-urethane (abbreviated to TPU) comprising a
flexible poly(oxyalkylene) block and a polyurethane block. The
polyurethane blocks can be obtained by reaction between a
diisocyanate, a diol and, if necessary, a chain-extending agent.
The flexible polyether blocks can be as described above in
connection with the PEBAs.
[0074] The diisocyanate is in particular an aliphatic diisocyanate,
such as hexamethylene diisocyanate (HMDI) or
2,2,4-trimethylhexamethylene diisocyanate; an alicyclic
diisocyanate, such as 1,4-cyclohexane diisocyanate,
4,4'-dicycloalkylmethane diisocyanate or isophorone diisocyanate
(IPDI); an aromatic diisocyanate, such as phenylene diisocyanate,
tolylene diisocyanate (TDI) or 4,4'-diphenylmethane diisocyanate
(MDI); an arylaliphatic diisocyanate, such as xylylene
diisocyanate; and others. Use may also be made, as diisocyanate, of
a compound having an alkyl group (for example, a methyl group)
substituted on a main chain of the compound or of a ring. The above
diisocyanates can be used alone or in combination.
[0075] Examples of the diol comprise a polyester diol [for example,
a polyester diol (aliphatic polyester diol) derived from an
aliphatic dicarboxylic acid component (for example, an aliphatic
C.sub.4-12 dicarboxylic acid, such as adipic acid), an aliphatic
diol component (for example, an aliphatic C.sub.2-12 diol, such as
ethylene glycol, propylene glycol, butanediol or neopentyl glycol)
and/or a lactone component (for example, a C.sub.4-12 lactone, such
as .epsilon.-caprolactone), for example a poly(ethylene adipate), a
poly(1,4-butylene adipate), a poly(1,6-hexylene adipate) or a
poly-.epsilon.-caprolactone], a polyether diol [for example, an
aliphatic polyether diol, for example a poly(C2-4 oxyalkylene)
glycol, such as a polyethylene glycol, a poly(oxytrimethylene)
glycol, a polypropylene glycol or a polytetramethylene glycol
(PTMG), and a poly(oxyalkylene) glycol block copolymer (for
example, a PEG-PPG block copolymer), or an aromatic polyether diol,
for example an addition product of an aromatic diol with an
alkylene oxide, such as a bisphenol A-alkylene oxide (for example,
an addition product of a C.sub.2-4 alkylene oxide, such as ethylene
oxide or propylene oxide)]; a polyesterether diol (a polyester diol
obtained by using the polyether diol as part of a diol component);
or a polycarbonate diol. This/these diol(s) can be used alone or in
combination. Among these diols, the polyester diol or the polyether
diol, such as polytetramethylene glycol, is used in many cases.
[0076] Use may be made, as chain-extending agent, of a glycol [for
example, a short-chain glycol, for example a C.sub.2-10 alkanediol,
for example ethylene glycol, propylene glycol, 1,4-butanediol or
1,6-hexanediol; or a bishydroxyethoxybenzene (BHEB)] and in
addition of a diamine [for example, an aliphatic diamine, such as a
C.sub.2-10 alkylenediamine, for example ethylenediamine,
trimethylenediamine, tetramethylenediamine or hexamethylenediamine,
an alicyclic diamine, such as isophoronediamine, or an aromatic
diamine, such as phenylenediamine or xylylenediamine]. The
chain-extending agent can be used alone or as a combination of
several types of chain extenders.
[0077] The preferred thermoplastic polyurethane (TPU) is obtained
by using a diol and a diisocyanate in substantially equivalent
amounts. Alternatively, the polyisocyanate comprises a small amount
of residual free (or unreacted) isocyanate, obtained by using an
amount of diisocyanate which is slightly in excess with respect to
the diol.
[0078] Preferably, use is made of a TPU obtained by using a diol
[for example, a polyester diol or polyether diol], a diisocyanate
and a glycol (for example, a short-chain glycol) as chain-extending
agent. The TPU comprises a hard segment (hard block), which is
composed of a polyurethane formed from a glycol and a diisocyanate,
and a soft segment (soft block) composed of a polyether diol [for
example, an aliphatic polyether diol (for example, a
poly(oxyethylene) glycol)], a polyester diol (for example, an
aliphatic polyester diol) or others. Mention may in particular be
made, as examples of TPU, of the following elastomers: polyester
urethane, polyester-ether urethane, polyether urethane,
polycarbonate urethane and others as a function of the entity of
the soft segment. Among TPUs, polyester urethane, polyester-ether
urethane or polyether urethane elastomers and their mixtures are
preferred. Furthermore, the number-average molecular weight of the
polyether (polyoxyalkylene glycol) is preferably within the range
from 100 to 10 000, preferably from 300 to 6000 and more preferably
from 500 to 4000.
[0079] The material C2 can comprise just one TPU or several of
these TPUs as a mixture.
[0080] Use may also be made, as TPE for the material C2, of a
copolyether-block-ester (abbreviated to COPE) comprising a flexible
poly(oxyalkylene) block and a polyester block. The polyester block
can be obtained by polycondensation by esterification of a
carboxylic acid, such as isophthalic acid or terephthalic acid or a
biobased carboxylic acid (such as furandicarboxylic acid), with a
glycol, such as ethylene glycol, trimethylene glycol, propylene
glycol or tetramethylene glycol. The flexible polyether blocks can
be as described above in the description of the PEBAs.
[0081] Another subject-matter of the present invention is the use
of a PEBA in a process of direct adhesion between two TPE materials
for increasing the peel strength between these materials,
characterized in that the PEBA is a copolymer according to the
invention described above.
[0082] A subject-matter of the present invention is in particular a
composition based on copolymer according to the invention described
above, the composition being characterized in that it comprises:
[0083] from 51 to 99.9% by weight of the said copolymer, [0084]
from 0.1 to 49% by weight of at least one other component chosen
from: PEBAs with a different composition and/or with a different
flexural modulus from that of the copolymer, PAs, POFs, COPEs,
TPUs, reinforcing fillers and/or fibres, in particular of glass or
of carbon, colourants, UV absorbers, antioxidants, in particular
phenolic antioxidants or antioxidants based on phosphorus or based
on sulphur, light stabilizers of hindered amine or HALS type, and
their mixtures.
[0085] A further subject-matter of the present invention is a
process for direct adhesion of a copolymer material (C1) according
to the invention with a TPE copolymer material (C2), C2 being of
identical composition to and having the same flexural modulus as
C1, or being of identical composition to but having a different
flexural modulus from C1, or C2 is a TPE material chosen from:
PEBAs of different compositions from that of the said copolymer C1,
COPEs and/or TPUs, the process according to the invention being
characterized in that the assembling is carried out by a process
comprising the heating of at least one of the two copolymer
materials C1 and/or C2, so as to cause one material to adhere to
the other.
[0086] According to an advantageous embodiment of the process of
the invention, the material C1 is melted or softened under heating
and the molten material C1 is brought into contact with at least a
portion of the material C2 of the series of the thermoplastic
polyurethanes TPUs in order to cause the two materials to
adhere.
[0087] According to a second advantageous embodiment of the process
of the invention, the material C2 of the series of the
thermoplastic polyurethanes TPUs is melted or softened under
heating and the molten material C2 is brought into contact with at
least a portion of the material C1 in order to cause the two
materials to adhere.
[0088] According to a third advantageous embodiment of the process
of the invention, the material C1 and the material C2 of the series
of the TPUs are independently melted or softened under heating and
the molten material C1 is brought into contact with at least a
portion of the molten material C2 in order to cause the two
materials to adhere.
[0089] Advantageously, in the assembling in process according to
the invention, the material C1 and the material C2 are assembled by
a direct adhesion process chosen from: overmoulding, hot pressing,
coextrusion, thermoforming, injection moulding, extrusion moulding,
blow moulding and their mixtures, preferably by overmoulding one
material over the other, preferably by overmoulding the copolymer
according to the invention over a TPE and preferably by
overmoulding the copolymer over a TPU.
[0090] Advantageously, the assembling temperature of the direct
adhesion process according to the invention is within the range
from 220 to 300.degree. C., preferably from 250 to 290.degree. C.
and preferably from 270 to 290.degree. C.
[0091] Such a process can, for example, be carried out by joining
the materials C1 and C2 in a moulding process, by injection
moulding, in particular two-material injection, two-colour
injection, multicolour, two-shot injection or co-injection
moulding. It is also possible to overmould a flexible material on a
rigid material, with a melting point Tm and/or glass transition
temperature Tg which are greater than those of the flexible
material. The PEBA according to the invention can, in addition, be
overmoulded on a metal insert. Other conventional processes can be
used: thermoforming, hot moulding in a moulding machine, insert
moulding, sandwich injection moulding, extrusion moulding, in
particular coextrusion moulding, injection-blow moulding and other
methods for processing TPE materials. A person skilled in the art
chooses the type of injection moulding machine according to the
type of mould, of insert and of materials to be injected.
[0092] According to a specific embodiment of the hot moulding in a
moulding machine, two materials C1 and C2 in the form of granules,
powder or any other form are charged to a metal mould. According to
another embodiment, two materials C1 and C2, in the form of
premoulded articles, are charged to a metal mould. According also
to a
[0093] According also to an embodiment of the insert injection
moulding, a moulded composite article can be produced by: moulding
either one of the materials C1 and C2 using a process such as
injection moulding or extrusion moulding, in particular of sheet or
of film, then the insertion or the forming in a metal mould of the
article thus moulded and then the injection of the other of the
materials C1 and C2, not yet moulded, into a space or a cavity
between the moulded article and the metal mould. In the insert
injection moulding, the moulded article which has to be inserted
into the metal mould is preferably preheated.
[0094] Another subject-matter of the present invention is a
composite article comprising at least two polymer materials which
adhere directly to one another, one with a composition according to
the invention described above and the other made of TPE chosen
from: identical PEBA (with a different flexural modulus from that
of the copolymer), PEBA of different composition from that of the
said copolymer, COPE and/or TPU.
[0095] Another subject-matter of the present invention is the use
of an article according to the invention in the manufacture of
sports equipment, of a component of footwear, in particular of
sports shoe, shoe sole, in particular crampon, component of a ski,
in particular of an Alpine, freeride, telemark or crosscountry ski
boot, of snow shoes or of a ski shell, of a metal device, of a
transmission belt, as antistatic additive, as waterproof-breathable
film, as support for active molecules, as colouring agent, as
welding agent, as decorative element and/or as additive for
polyamide.
[0096] The article can in particular be at least a part portion
chosen from motor vehicle parts, textiles, woven or nonwoven
materials, clothing, footwear, sports equipment, recreational
equipment, electronic objects, computer hardware, healthcare
equipment, spectacles, industrial additives, packaging and
household products. Mention may in particular be made of
dashboards, air bags, soles for sports shoes, golf balls, tubes for
medical use, catheters, angioplasty balloons, peristaltic belts,
the belts of conveyor belts, waterproof-breathable products,
synthetic leather and/or skin, thermoplastic films or packaging
films.
Examples
[0097] The following examples illustrate the invention without
limiting it. The standards used in the examples also correspond to
those used more generally to characterize the invention in the
description or the claims.
Materials Used;
[0098] In the examples which follow:
PEBA 1: PA 12-PTMG (Mn: 400-1000)
[0099] PEBA 1 is a copolymer having PA 12 blocks and PTMG blocks
with respective number-average molecular weights (Mn) 400-1000.
PEBA 2: PA 6.10-PTMG (2500-650)
[0100] PEBA 2 is a copolymer according to the invention having PA
6.10 blocks and PTMG blocks with respective number-average
molecular weights (Mn) 2500-650.
PEBA 3: PA 11-PTMG (1000-1000)
[0101] PEBA 3 is a copolymer having PA 11 blocks and PTMG blocks
with respective number-average molecular weights (Mn) 1000-1000.
TPU 1 is an aromatic TPU having ether (PTMG) blocks, with a Shore A
hardness of 95 and with a flexural modulus of 53 MPa, of
Elastollan.RTM. 1195A trademark (BASF). TPU 64 Shore D is an
aromatic TPU having ether (PTMG) blocks with a Shore A hardness of
95, of Elastollan.RTM. 1164D trademark.
Example 1--Comparison of the Peel Strengths (Kg/Cm) after
Overmoulding Different PEBAs on TPU or PEBA Insert
[0102] A peel test according to Standard ISO 11339 was carried out
on the products overmoulded at different injection moulding
temperatures. The results of these tests are given in Table 1. The
adhesion of different compositions of PEBAs on TPU insert or on
PEBA insert, after direct adhesion by overmoulding at different
injection moulding temperatures, is compared in the following Table
1.
TABLE-US-00001 TABLE 1 Peel strengths (kg/cm) for different
injection moulding temperatures (.degree. C.) Insert Grade 250 260
270 280 TPU 1 PEBA 1 7 3 PEBA 2 14 14 18 PEBA 2 + PEBA 3 8 (30/70)
PEBA 1 + PEBA 2 12 14 (50/50) TPU 2 PEBA 1 10 PEBA 4 15.5 PEBA 2
PEBA 2 9.3 PEBA 2 + PEBA 2 + PEBA 3 13 12 PEBA 3 (30/70)
(30/70)
[0103] It is found that PEBA 2 (PA 6.12-PTMG) according to the
invention exhibits an excellent adhesion to TPU, characterized by a
peel strength of 14 kg/cm obtained for an overmoulding temperature
of 250.degree. C.
[0104] Furthermore, a composition according to the invention
comprising 50% by weight of PEBA 1 and 50% by weight of PEBA 2
exhibits a markedly improved direct adhesion to TPU (8 kg/cm) with
respect to the comparative PEBA 1 alone (3 kg/cm), after
overmoulding on a TPU insert at 270.degree. C. The overmoulding of
PEBA 2 on itself at 270.degree. C. also results in an adhesion in
accordance with that of the invention, with a peel strength of
greater than 9 kg/cm.
[0105] Likewise, the dry blend mixture of PEBA 2 (30% by
weight)+PEBA 3 (70% by weight) exhibits a direct adhesion of at
least 12 kg/cm to TPU or to the moulded product itself (obtained
from the same dry blend mixture).
Example 2--Comparison of the Mechanical Properties
Flexural Modulus (MPa) According to Standard ISO 178:
TPU 64 Shore D: 270 MPa
PEBA 1: 285 MPa
PEBA 2: 320 MPa
Cold Stiffening:
[0106] measured by the change in the E' modulus (MPa) as a function
of temperature T or by the change in the E'(T)/E'(23.degree. C.)
ratio as a function of the temperature over the range -40.degree.
C. to +23.degree. C. (Graph of FIG. 1):
The lower the value of this ratio, the less the stiffness of the
product changes. As is shown in Graphs 1 and 2, PEBA 2 according to
the invention, like PEBA 1, exhibits a lower cold stiffening
between -40 and 23.degree. C. than TPU 64 Shore D.
Tan .delta.: Damping Factor/Liveliness Test at Ambient Temperature
(23.degree. C.):
[0107] The liveliness test consists in stressing the end of a test
specimen and in observing the frequency of the oscillations and the
time necessary for the damping of these oscillations. The movement
of the end of the material is reflected by a sine wave (of the
y=y.sub..alpha.e.sup.-.alpha.t cos(.omega.t) type), the amplitude
of which decreases over time. The higher the frequency and the
lower the damping, the more the material is regarded as lively.
The liveliness index L is defined by L = f tan ( .delta. )
##EQU00001##
with f the oscillation frequency,
[0108] tan .delta. the damping factor calculated from the
parameters .alpha. and .omega.=2.pi.T:
Tan .delta. = 2 .alpha..PI. .PI. 2 + .alpha. 2 ##EQU00002##
The tests were carried out at 23.degree. C. Two levels of
deformation were applied: 1% and 3%, and the liveliness results are
shown in the following Table 2:
TABLE-US-00002 TABLE 2 PEBA 2 PEBA 1 1% def. (23.degree. C.)
Frequency (Hz) 43 .+-. 1 51 .+-. 1 Tan .delta. 0.117 0.118 3% def.
(23.degree. C.) Frequency (Hz) 124 .+-. 4 141 .+-. 1 Tan .delta.
0.147 0.136
The frequency of oscillation of PEBA is slightly higher than that
of PEBA 2. The tan .delta. values are substantially the same for
PEBA 1 and PEBA 2. Likewise, the liveliness indices of PEBA 1 and
PEBA 2 are relatively similar. These results show that PEBA 2
according to the invention exhibits a dynamic behaviour with a
spring effect, and thus a good "liveliness".
Notched (V) Charpy Impact Test
[0109] The resilience R.sub.ch (kJ/m.sup.2) at 23.degree. C. of the
3 TPEs is measured according to Standard ISO 179 leA. The results
obtained are shown in the following Table 3:
TABLE-US-00003 TABLE 3 PEBA 2 TPU 64 according to Shore D the
invention PEBA 1 R.sub.ch (kJ/m.sup.2) Nonbreaking Nonbreaking
Nonbreaking V notch, 23.degree. C.
At 23.degree. C., PEBA 1, PEBA 2 and TPU 64 Shore D have a similar
behaviour; in the three cases, the product does not break.
Fatigue Behaviour--Ross Flex Test (Standard ASTM D1052)
[0110] The Ross flex test is a fatigue test used to evaluate the
longevity of the materials when the latter are repeatedly stressed
in flexion (frequency of 1.7 cycles/s). The test makes it possible
to say if the product breaks or not after n cycles (generally n=150
000). Typically, the deformation applied is of the order of 5% for
a test specimen of 2 mm stressed with an angle of 600. This
deformation depends on the thickness of the material and on the
angle of stress.
[0111] At an unvarying radius of curvature, the more the thickness
t increases, the more the deformation increases. At an unvarying
thickness, the more the radius of curvature R decreases, the more
the deformation increases.
The deformation applied to the test specimen is given by:
= t 2 ( R - t / 2 ) ##EQU00003##
Angle of stress: 60.degree. Test specimen width: 20 mm
Temperature: -10.degree. C.
[0112] Number of cycles: 150 000 Frequency: 100 cycles/min. PEBA 1
and PEBA 2 exhibit a good fatigue strength since they pass the 150
000 cycles. Furthermore, PEBA 2 passes the 150 000 cycles after
having been subjected to a heat treatment under the following
conditions: 7 days at a temperature of 70.degree. C. and a humidity
of 95%.
Comparison of the Density of Different TPEs
[0113] The density is measured according to Standard ISO 1183:
TPU 64 Shore D: 1.24
PEBA 1: 1.01
PEBA 2: 1.06
* * * * *