AU654605B2

AU654605B2 - New transparent amorphous compositions with high resistance to chemical agents

Info

Publication number: AU654605B2
Application number: AU30473/92A
Authority: AU
Inventors: Philippe Blondel; Philippe Maj
Original assignee: Elf Atochem SA
Current assignee: Arkema France SA
Priority date: 1991-12-31
Filing date: 1992-12-30
Publication date: 1994-11-10
Anticipated expiration: 2012-12-30
Also published as: EP0553581A3; FI925934A; DE69225307T2; DE69225307D1; CN1032364C; NO924851L; KR970000096B1; NO924851D0; CA2086500C; JPH05311066A; EP0553581A2; FI109471B; CN1073954A; NO180238B; ATE165613T1; DK0553581T3; NO180238C; KR930013000A; FR2685702A1; ES2116327T3

Abstract

New transparent amorphous compositions and, more particularly, transparent amorphous compositions exhibiting high resistance to chemical agents (solvents), and objects manufactured from these . These compositions comprise two polyamides consisting of aliphatic units, teraphthalic and/or isophthalic acid and cycloaliphatic diamine. One of the two polyamides has a high content of aliphatic unit while the other has a low content of aliphatic unit.

Description

i-/UIW1 28/1g Regulation 3.2(2)

AUSTRALIA

Patents Act 1990 654

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: C. Ut C C C C I It., Itt C

'CCC

''Cc, CC CC It C Invention Title: NEW TRANSPARENT AMORPHOUS COMPOSITIONS WITH HIGH RESISTANCE TO CH EMICAL AGENTS Cc c C C C C~.

CCtC C C C IC I, I I

I.

0*I**I

I

C It

C

1t1 C, C~

CL

C

The following statement Is a full description of this Invention, Including the best method of performing it known to :-US

(I

Y1 S1 NEW TRANSPARENT AMORPHOUS COMPOSITIONS WITH HIGH RESISTANCE TO CHEMICAL AGENTS The present invention relates to new transparent amorphous compositions and, more particularly, to transparent amorphous compositions exhibiting a high resistance to chemical agents (solvents), and to the objects manufactured from these compositions.

EP-A-0,313,436 (in the name of the Applicant) and FR-A-2,575,756 and FR-A-2,606,416 (EMS) describe and claim transparent amorphous polyamides consisting of aliphatic units containing more than 7 carbons, of cycloaliphatic diamine and of terephthalic and/or isophthalic acid. These amorphous polyamides exhibit a resistance to chemical agents (solvents) which is a function of the weight proportion of aliphatic unit in t* the amorphous polyamide. In order to assess the resistance to chemical agents (solvents) the absorption .t of ethanol is often employed as a parameter. Thus, in the abovementioned cases, when the absorption of ethanol is plotted as a function of the weight proportion of aliphatic unit, the curve thus obtained is bell-shaped. In the case of low percentages the it absorption is low and therefore the solvent resistance tt t is good, and in the case of high percentages the/ results are identical. On the other hand, in the case of intermediate percentages the absorption is high and therefore the resistance to chemical aqents (solvents)

~I~C

LI II i~ 2 is low.

In the case of low weight proportions of aliphatic units the polyamide contains high proportions of aromatic diacid and of cycloaliphatic diamine, which are costly compounds, and consequently this polyamide itself is expensive. In the case of high weight proportions of aliphatic units the polyamide is undoubtedly moderate in cost but exhibits the disadvantage of poor thermal and mechanical properties.

Thus, a person skilled in the art searching for a transparent amorphous polyamide which has a high resistance to chemical agents (solvents) is not tempted to employ polyamides with intermediate percentages of aliphatic units, since these are not appropriate, and must therefore either choose polyamides with a low proportion of aliphatic unit, that is to say high in cost, or polyamides with a high proportion of aliphatic unit, that is to say with poor mechanical and thermal properties.

Surprisingly, the Applicant has found that these disadvantages are circumvented by virtue of the present invention.

Thus, the present invention provides a transparent amorphous composition with high resistance to chemical agents comprising, by weight: J a) 1 to 99 of a first polyamide characterised by the chain sequences: 2* 2 2 8 4 2e 2 Ir 42 (L 'I 0..2 22*8 It I 04 0 0

NH-

RNH Z'0NH

Z'-NH

and 4 irt

S

C

W*95 *6 S I 4 *5 0

C

I I 0 0 Z- N-RNH-C- Z'--NH m Y2 in which: yl and Y2 are numbers whose sum yl Y2 is between 10 and 200; m, p, m' and p' are numbers equal to or greater than 0; Z and in the aliphatic units -NH-Z-CO- and which are identical or different, are either a polymethylene segment C H 2 where n is an integer equal to or greater than 6 and preferably between 7 and 11, or a sequence containing an amide functional group resulting from the substantially stoichiometric condensation of one or more aliphatic diamine(s) containing at least 4 carbon atoms between the amine functional groups and of one or more aliphatic dicarboxylic acid(s) containing at least 4 and preferably at least 6 carbon atoms between the acidic func"onal groups; -HN-R-NH- denotes a cycloaliphatic and/or aliphatic and/or arylaliphatic amine; it being possible for the aromatic diacid to be replaced, in a proportion of at most 30 mol%, b'y an aliphatic dicarboxylic acid containing more than 4, preferably 6, carbon atoms between the acidic functional groups, b) the said chain sequences being present in such proportions that the aliphatic units represent less than 55% by weight of the said first polyamide; and 99 to 1 of a second polyamide characterised by the chain sequences: 00- 0 11~~ I11 Cff-NH-Zi'--C k N -R1 NH C-Z-N fl~" Y1 a t a as Sta.

cast alas a a sass CS St at a S a a S oats pa..

at pap, a .h P a a a. P -a a a .a p p and 0

CC

0 0 I I PY2.

in which: y' and y'2 are numbers whose sum y' Y'2 is between 10 and 200; and are numbers equal to or greater than 0; Z" and 7 in the aliphatic units -NH-Z"-CO- and which are identical or different, are either a polymethylene segment -fCH 2 I where n' is an integer equal to or greater than 6 and preferably between 7 and 11, or a sequence containing an amide functional group resulting from the substantially stoichiometric condensation of one or more aliphatic diamine(s) containing at least 4 carbon atoms between the amine functional groups and of one or more aliphatic dicarboxylic acid(s) containing at least 4 and preferably at least 6 carbon atoms between the acidic functional groups; -HN-R'-NH- denotes a cycloaliphatic and/or aliphatic and/or arylaliphatic amine; .it being possible for the aromatic diacid to be replaced, in a proportion of at most 30 mol%, Si by an aliphatic dicarboxylic acid containing more than 4, preferably 6, carbon atoms .between the acidic functional groups, the said chain sequences being present in such proportions that the aliphatic units represent S /1/ ii i~ 'i 6 more than 55 by weight of the said second polyamide.

The aliphatic units and are obtained during the synthesis, starting from lactam, from corresponding amino acid or from a substantially stoichiometric condensation of one or more aliphatic diamine(s) and of one or more aliphatic dicarboxylic acid(s). The lactams contain at least 7 carbon atoms, preferably 8 to 12. The preferred lactams are capryllactam or lactam 8, dodecanelactam, undecanelactam, lauryllactam or lactam 12, denoted hereinafter by L12. L12 resulting in the unit 12 is particularly preferred.

The corresponding amino acid is the -aminoacid containing as many carbon atoms as the corresponding lactam. The w-aminoacids contain at least 7 carbon atoms, preferably 8 to 12. The preferred I-aminoacids are 10-aminodecanoic acid, S; 11l-aminoundecanoic acid and 12-aminododecanoic acid.

The aliphatic dicarboxylic acid is an a,o- Sdicarboxylic acid containing at least 4 carbon atoms (not including the carbon atoms of the carboxyl group), preferably at least 6, in the linear or branched carbon 4 t chain. The preferred dicarboxylic acids are adipic acid, azelaic acid, sebacic acid and l,12-dodecangic acid.

The term "aliphatic diamine" as employed in the present invention denotes an a,a-diamine containing 7 at least 4 carbon atoms, preferably 6 to 12, between the terminal amino groups.

The carbon chain is linear (polymethylenediamine) or branched. Mixtures of aliphatic diamines are also envisaged in the present invention. Preferred aliphatic diamines are hexamethylenediamine (HMDA), 2,2,4- and/or 2,4,4trimethylhexamethylenediamine, dodecamethylenediamine, tri methylhexamethylenediamine, m ethylpentamathyl rie-diamine, methylnonamethylenediamine and decamethylenediamine.

The term "cycloaliphatic diamine" as employed in the present invention denotes an amine of formula: x x l

A(A')

H

2 N C NH 2 B(B)

B(B')

S; IY') q(q) B(B') m(m')

S

t in which: and which are identical or different, denote hydrogen,

S

1 the methyl radical, the ethyl radical or the isopropyl radical; 15 and which are identical or different, denote hydrogen or the methyl radical; is an integer between 0 and 6; 1/1 8 has the value 0 or 1.

Mixtures of cycloaliphatic diamines are also envisaged in the present invention.

The term "cycloaliphatic diamine" also covers, within the meaniLg of the present invention, the diamines containing a cycloaliphatic structure as defined by the above formula in their carbon chain.

Isophoronediamine and 3,6-diaminomethyltricyclodecane may be mentioned by way of example. Examples of cycloaliphatic diamines are, no limitation being implied: isophoronediamine, bis(4-aminocyclohexyl)methane (BACM), bis(3-methyl-4-aminocyclohexyl)metharne (BMACM), bis(3-methyl-4-amino-5-ethylcyclohexyl)methane, 1,2-bis(4-aminocyclohexyl)ethane, 2,2'-bis(4aminocyclohexyl)propane and 2,2'-bis(3-methyl-4-aminocyclohexyl)propane.

The term "arylaliphatic diamine(s)" as employed in the present invention denotes the amines of formula: H2N-RI&A-r-R2-NH2 in-which: R,.and R 2 which are identical or different, are linear or branched Cl-C, hydrocarbon residues; Ar is a divalent aromatic radical which denotes am aromatic ring or two or more aromatic rings bonded by an alkyl group, it being furtheamore possible for the said radical Ar to be substituted according to any configuration, ortho, meta or para.

-i ;a iK 1 i4 2 9 Mixtures of arylaliphatic diamines are also envisaged in the present invention. By way of example there may be mentioned meta-xylylenedianmine (in the case of which Ar m-phenyl, R I

R

2

-CH

2 Saturated derivatives or those comprising an arometic-aliphatic structure in their carbon chain are also envisaged in the present invention. 1,3-Bisaminomethylcyclohexane and 1,3-diaminomethylnorbornane may be mentioned by way of example.

Mixtures of aliphatic and/or cycloaliphatic and/or arylaliphatic diamine(s), especially of isomers, are also envisaged in the present invention.

The term "substantially stoichiometric" denotes a diamine/diacid molar ratic of between 1.1/1 and 1/1.1.

Thus, the term "substantially stoichiometric condensation of one or more diamine(s) and of one or more diacid(s)" may, for example, denote the 6,6 or 6,12 unit. The term "amorphous polyamide"' as employed trC Sin-the present invention denotes a polyamide whose heat m of fusion, measured by TSC at 20 0 C/min after cooling at t" 40C/min is lower than 3 cal/g.

The term "transparent polyamide" as employed in the present invention denotes a polyamide whose transmission factor is at least 70 when this :1 I polyamide is in the form of a thin plate 2 mm in thickness.

According to a preferred embodiment of the i c eodn more afreape eoete66o present invention, in the said first polyamide the aliphatic units represent less than '2 by weight of the said first polyamide, advantageously less than According to another preferred embodiment of O the present invention, in the said second polyamide the aliphatic units represent more than 60 by weight of the said second polyamide, advantageously more than The composition preferably comprises, by weight: a) 5 to 95 of the said first polyanide; and b) 95 to 5 of the said second polyamide.

The composition advantageously comprises, by weight: a a) 20 to 80 of the said first polyamide; and C b) 80 to 20 of the said second polyamide.

According to a preferred embodiment of the present invention the aliphatic units of the -said first Sand second polyamides are chosen from the group consisting of the units originating from capryllactam, t lauryllactam, 12-aminododecanoic acid, 11-aminoundecanoic acid, 10-aminododecanoic acid and mixtures thereof. Advantageously, the aliphatic unit of the said first and second polyamides is the unit 12 originating from lauryllactam.

According to another preferred embodiment of the present invention the diamine of the said first and I o 11 i second polyamides is a cycloaliphatic diamine. The said diamine advantageously has the formula:

X(X')

A(A')

H

2 N C NH 2

B(B')

Y(Y')

in which: ,o L and which are identical or different, denote the hydrogen atom or the methyl radical; and which are identical or different, denote the ~hydrogen atom or the methyl radical; and C 10 is an integer between 1 and 3; optionally replaced up to 50 mol% by isophoronediamine.

The cycloaliphatic diamine of the said first and second polyamides is preferably bis(3-methyl-4-aminocyclohexyl)methane or bis(4- 1 aminocyclohexyl)-methane, optionally replaced up to 50 mol% by 15 isophoronediamine.

I" Another embodiment of the present invention consists of a to, composition in which, in the said first and/or second polyamide(s), the ratio y1/yi+y2 and/or i i 12 the ratio y'I/y'1+y' 2 is (are) greater than The polyamides can be synthesised by any appropriate procedure known in the art. They are preferably prepared by the process as'described and claimed in EP-0,313,436 in the name of the Applicant.

The compositions according to the present invention can be prepared by any mixing process known to a person skilled in the art, provided that -the mixing is carried out at a sufficient temperature for the polyamides to be in the molten state.

A preferred process is compounding, which consists in charging the polyamides in the form of granulates into a conventional extruder at a temperature above the glass transition temperature Tg, advantageously between 250"C and 400"C.

TAnother process consists in mixing the said first and second polyamides, at least one of which is preferably in the state of a prepolymer whose degree of polymerisation is at least 50 in the presence of an S.t amidification or transamidification catalyst such as phosphoric or hypophosphorous acid.

The compositions according to the present Sinvention are amorphous and transparent, with a high resistance to chemical agents (solvents) c,nd good rechanical and thermal properties, whereas the /J polyamide exhibiting the same proportion of alipha ic i' I unit but obtained directly by synthesis has a mediocre leI c I solvent resistance. 13 Other components may be added to the present composition, such as conventional additives and fillers, or another polyamide. This latter polyamide may be an amorphous polyamide as described above.

The conventional additives include,.for example, light and/or heat stabilisers, colorants, optical brighteners, plasticisers, demoulding agents, flame-retardant agents and others. Conventional fillers include, for example, inorganic fillers such as slag, kaolin, magnesia, talc and glass fibres.

Another subject of the present invention is therefore a composition additionally comprising a conventional filler and/or additive.

Another subject of the present invention is also the objects obtained from the present transparent amorphous composition. These objects may be S* manufactured by any conventional process such as extrusion, injection moulding and the like.

In the examples which follow, the flexural modulus is determined according to ASITi standard D 790 after conditioning. The ethanol absorption is measured Institut Frangais du Caoutchouc on test pieces of IFCdtype 2 mm in thickness and approximately 1 g in weight, predried, after 8 days' immersion in pure ethanol at 25"C. The value is given as a percentage increase in weight. The following examples are given by way of 7 illustration of the present invention and must not be considered at limiting the scope thereof, since it is 14 capable of numerous alternative forms which are easily accessible to a person skilled in the art.

EXAMPLES 1 TO 3 Examples 1 to 3 are carried'out by melt compounding with the aid of a Haake laboratory twin screw extruder from mixtures of granulates of transparent polyamides synthesised in the molten state.

The transparent polyamides are synthesised from lauryllactam (L12), terephthalic (TA) and isophthalic (IA) acids and bis(3-methyl-4-aminocyclohexyl)methane (BMACM). The polyamides A and B and their respective proportions by weight are much that the proportion by weight of aliphatic unit in the final mixture is identical for the four examples.

EXAMPLE 4 (comparative) This comparative example is the polyamide obtained by direct synthesis, which has the same proportion by weight of aliphatic unit as in Examples 1 to 3.

The molar compositions, the percentage by weight of aliphatic unit that is to say L12 the mass fractions of the polyamides in the mixture, the

C

compounding conditions temperature and speed and '.*the properties of the polyamides (EtOH absorption, flexural modulus) for Examples 1 to 4 are listedlin Table 1.

~1&i II I JJWUII~RJ~MtIWJ~I!I.NjL~J jWjiIpI.UUU'*** I TABLE 1 PA (A~ PA .L12ITA/ Ex. IA/BI4ACM 2 3 4 1/0.7/0.3/1 1/0.7/0.3/1 1/0,7/0.3/1 L12 weight 33.0 33.0 33.0 EtOH abs.

44- 44 44 L12/TA/ L12 IA/BNACM weight 8/1/0/1 79-8 7/1/0/1 77.5 .8/1/0/1 65.2 .9/1/0/1 48.3 EtOll abs.

16.6 17 26.3 53 of B in the mixture 30.8 32.2 44.2 100 Temperature 0 C)/speed (rnv/minh Modulus MPa 2 80/6 0 28 0/6 0 280/60 2 80/6 0 4 80 1640 1640 1610 EtOH abs.

29 29 33 53 1

-A

1>2 N~J~ 16 EXAMPLES 5 TO 11 AND 12 (comparative) The examples were carried out according to the operating procedure of Example 1. The results are listed in Table 2.

Example 12 is the comparative example in which the proportion by weight of aliphatic unit is equal to that of Examples 5 to 11.

C

C Cs SC t4t C CC

I

C

0 I C L

A

TABLE 2.

PA PA (B) Ex.

6 7 8 9 11 12 L12ITA/ TA1BNACM 1/0.7/0.3/1 1/0.7/0.311 1/0.7/0.3/1 1/0.710.3/1 1/0.7/0.3/1 1/0.7/0.31 110.7/0.3/1 L12 weight 33.0 33.0 33.0 33.0 33.0 33.0 33.0 Et ab 4 4 4 4 4 4 4

OH

'S.

L12/TA!

IA/BMACM

4 30/1/0/1 4 20/1/0/1 4 13/1/0/1 4 10/1/0/1 4 8/1/0/1 4 7/1/0/1 4 3.8/1/0/1 2.4/1/0/1 L12 weight 93.7 90.8 86.5 83.1 79.8 77.5 65.2 54.2 EtOH abs.

of B in the mixture 36 37 .8 40.6 Temperature (OC) /speed (rev/min) 320/60 320/60 320/60 32 0/60 280/60 2 80/60 2 80/60 Modulus EtQH MPa abs.

_L I-U 1720 24 1690 24.4 16160 24.9 1650 25.7 1580 26.1 1610 27.3 1550 1550 43 43.3 46.2 48.5 66.4 a 18 EXAMPLES 13 TO 19 In these examples, which are similar to Examples 1 to 3, the polymer with a low proportion of aliphatic unit is synthesised from L12, TA, IA and BMACM, while the polymer with a high proportion of aliphatic unit is synthesised from L12, TA, IA and bis(4-aminocyclohexyl)methane (BACM).

The compositions, operating conditions and properties of the transparent polymers obtained by compounding are given in Table 3.

Si i C C lk-I f WWWWANWA"N "MiN P.

TABLE 3 PA v PA (B) Ex.

13 14 16 17 18 19 L121TAI L12 IAIB4ACI4 weight 1/0.7/0.3/1 33.0 1/0.7/0.3/1 33.0 1/0.710.311 33.0 110.7/0.3/1 33.0 1/0.7/0.3/1 33.0 1/0.85/0.25/1 32.1 1/0.8/0.2/1 33.0 EtOl abs.

.44 44 44 44 44 39.2 40.6 L12/TA/ IA/B4ACI4 7/1/0/1 7/1/0/1 7/1/0/1 7/1/0/1 7/110/1 7/1/0/1 7/1/0/1 L12 EtOH of B in weight 34.6 34.6 34.6 34.6 34.6 34.6 34.6 abs.

LUi 17 17 17 17 17 17 17 the mixture 10 30 50 70 90 45 45 Temperature (OC) /speed (rev/min) 280/60 280160 280/60 280/60 280/60 2 80/6 0 280/60 Moc

I

2 2

J

I

lulus EtOH 4Pa abs.

_Lu_ 1850 37.6 1780 L600 23.7 L450 ~305 17.8 607 24.5 28.9 t aft. fl I EXAMPLES 20 AND 21 These examples are implemented according to the same operating method as Example 1. The results are listed in Table 4.

EXAMPLES 22 TO 24 These examples are implemented according to the same operating method as Example 1. In these examples the diacid is exclusively isophthalic acid.

The results are listed in Table 4.

EXAMPLE 25 (comparative) The polyamide according to Example 25 is obtained by direct synthesis and has the same composition by weight as that of Example 24. The results are listed in Table 4.

i a

I\

TABLE 4 PA (A)b PA (B I Ex.

21 22 23 24 L12/TA/IAIBMAC4 0.8/0.6/0.4/1 0.8 /0.6/0.4/1 1/0/1/1 110/1/1 2.4/0/1/1 L12 weight 28.3 28.3 33.0 33.0 54.2 L12/ITA/IA/BMACM 7/1/0/1 7/1/0/1 7/0/1/1 7/0/111 L12 weight 77.5 77.5 77.5 77.5 cf B in the mixture 40 50 0 100 48.5 Temperature (OC) /speed (rev/mnin) 280/60 280/60 310/130 EtOH abs.

28.7 26.4 dissolved 19 29 dissolved

I

Claims

1. Transparent amorphous composition with high resistance to chemical agents, comprising, by weight: a) 1 to 99 of a first polyamide characterised by the chain sequences: O 0 0 I II and C p Y O in which: yl and Y2 are numbers whose sum yi Y2 is between 10 and 200; m, p, m' and p' are numbers equal to or greater than 0; Z and in the aliphatic units -NH-Z-CO- a.J -NH-Z'-CO, which H 2 n-2 where n is an !nteger equal to or greater than 6 and preferably between 7 and 11, or a sequence containing an amide functional group resulting from the substantially stoichiometric condensation of one or more aliphatic diamine(s) containing at least 4 carbon atoms between the amine functional groups and of one or more aliphatic dicarboxylic acid(s) containing at least 4 and preferably at least 6 carbon atoms between the acidic functional groups; ff *K^Krb 23 -HN-R-NH- denotes a cycioaliphatic and/or aliphatic and/or arylaliphatic amine; it being possible for the aromatic diacid to be replaced, in a proportion of at most 30 mol%, by an aliphatic dicarboxylic acid containing more than 4, preferably 6, carbon atoms between the acidic functional groups, the said chain sequences being present in such proportions that the aliphatic units represent less than 55% by weight of the said first polyamide; and b) 99 to 1 of a second polyamide characterised by the chain S. sequences: S- O II II I II S: C- Z- NH .L p, C 1 [NH C NH and Si t a u w NH-- C P' i Y2 0 in which: y'i and y' are numbers whose sum y'i Y'2 is between 10 and 200; rrm"' and are numbers equal to or greater than 0; Z" and in the aliphatic units -NH-Z"-CO- and which are identical or different are either a polymethylene segment -(CH 2 where is an integer equal to or greater than 6 and preferably between 7 and 11, or a sequence containing an amide functional group resulting from the substantially P 0 ci 1 24 stoichiometric condensation of one or more aliphatic diamine(s) containing at least 4 carLhn atoms between the amine functional groups and of one or more aliphatic dicarboxylic acid(s) containing at least 4 and preferably at least 6 carbon atoms between the acidic functional groups; -HN-R'-NH- denotes a cycloaliphatic and/or aliphatic and/or arylaliphatic amine; it being possible for the aromatic diacid to be replaced, in a proportion of at most mol%, by an aliphatic dicarboxylic acid containing more than 4, preferably 6, carLbn atoms between the acidic functional groups, the said chain sequences being present in such proportions that the aliphatic units represent more than 55 by weight of the said second polyamide. 1first polyamide. 3. Composition according to Claim 1, characterised in that, in the said first polyamide, the aliphatic units represent less than 45 by weight of the said first polyamide. C t

4. Comoosition according to any one of Claims 1 to 3, characterised in that, in the said second polyamide, the aliphatic units represent more than S by weight of the said second polyamide. Composition according to Claim 4, characterised in that, in the said second polyamide, the aliphatic units represent more than 70 by weight of the said second polyamide.

6. Composition according to any one of Claims 1 to 5, comprising, by weight: a) 5 to 95 of the said first polyamide; and b) 95 to 5 of the said second polyamide.

7. Composition according to Claim 6, comprising, by weight: a) 20 to 80 of the said first polyamide; and b) 80 to 20 of the said second polyamide.

8. Composition according to any one of Claims 1 to 7, characterised ir that the aliphatic units of the said first and second polyamides are chosen from the group consisting of the units originating from capryllactam, lauryllactam,

12-aminododecanoic acid, 11-aminoundecanoic acid, acid and mixtures thereof. 9. Composition according to any one of Claims 1 to 8, characterised in that the aliphatic unit of the said first and second polyamides is the unit 12 originating from lauryllactam. 10. Composition according to any one of Claims 1 to 9, characterised in that the diamine of the said first and second polyamides is a cycloaliphatic l: diamine. tu 11. Composition according to Claim 10, characterised in that the said cycloaliphatic diamine of the said first and second polyamides has the formula: X(X') ,t x(x') A(A') H 2 NB C 2\ B(B B B(B') f Y(Y') I~ S4 P 0 2,6 cr rI Cr C t C CC CCI ii I~ C Cf C in which: A and B which are identical or different, denote the hydrogen atom or the methyl radical; X and Y which are identical or different, denote the hydrogen atom or the methyl radical; and q is an integer between 1 and 3; optionally replaced up to 50 mol% by isophoronediamine. 12. Composition according to Claimll', characterised in that the cycloaliphatic diamine of the said first and second polyamides is bis(3-methyl-4- aminocyclohexyl)methane or bis(4- aminocyclohexyl)methane, optionally replaced up to mol% by isophoronediamine.

13. Composition according to any one of Claims 1 to 12 characterised in that, in the said first and/or second polyamide(s), the ratio yl/yi+y 2 and/or the ratio y' 1 /y'I+y' 2 is (are) greater than

14. Composition according to any one of Claims 1 to 13, characterised in that it additionally comprises a conventional filler and/or additive. Objects obtained from a composition according to any one of Claims 1 to 14. DATED this 29th day of December 1992. ELF ATOCHEM S.A. WATERMARK PATENT TRADEMARK ATTORNEYS "THE ATRIUM" 290 BURWOOD ROAD HAWTHORN. VIC.3122. i I- ABSTRACT The present invention relates to new' transparent amorphous compositions and, more S• particularly, to transparent amorphous compositions exhibiting a high resistance to chemical agents j (solvents), and to the objects manufactured from these compositions. These compositions comprise two polyamides .consisting of aliphatic units, terephthalic and/or S" isophthalic acid and cycloaliphatic diamine. One of the Se. two polymers has a high aliphatic unit content whereas the other has a low aliphatic unit content. *f 1__