FR2665172A1 - Polyamide-based compositions which make it possible to obtain moulded articles which have a good flame resistance - Google Patents

Abstract

Compositions based on at least 80 % by weight of polyamide, containing at least one polysiloxane consisting essentially of phi R1SiO2/2 units optionally with R2R3SiO2/2 units, in which: - phi denotes a phenyl group optionally substituted by one or more halogen atoms and/or by one or more methyl groups, - R1 may have the meaning given for phi above, or may be an alkyl group containing from 1 to 10 carbon atoms or a cycloalkyl group containing from 3 to 10 carbon atoms, - R2 may have the meaning given for phi above or may have the meaning of R3 below, - R3 denotes an alkyl group containing from 1 to 10 carbon atoms or a cycloalkyl group containing from 3 to 10 carbon atoms. These compositions make it possible to obtain, at high rates of manufacture, shaped articles which have a good flame resistance.

Description

POLYAMIDE-BASED COMPOSITIONS FOR OBTAINING
MOLDED ARTICLES HAVING GOOD RESISTANCE
AT THE FLAME
The present invention relates to polyamide-based compositions for the manufacture of shaped articles having good flame resistance, such as for example clamps for electric wires or cables.

 Another object of the present invention relates to polyamide-based compositions for obtaining articles shaped at high production rates, for example according to the injection technique.

Another object of the present invention relates to polyamide-based compositions making it possible to obtain, at high production rates, flame-resistant shaped articles, particularly satisfying the UL 94 V 2 vertical test of the "Underwriters Laboratories". (as described in document 9750-1 of the Bureau of Standards of
Plastics "with specimens with dimensions 127 x 12.7 x 0.8 mm), while maintaining good mechanical and physical properties.This UL 94 V test is also described in Test for flammability of plastics material for parts in devices UL 94 Standard 3rd Edition or ANSI / UL 94-85, under 0.8 mm.

It has now been found and this is the subject of the present invention a composition based on polyamide characterized in that it comprises a polysiloxane consisting essentially of units R1SiO2 / 2 with possibly units R2R3SiO2 / 2 in which
f represents a phenyl group optionally substituted with one or more halogen atoms and / or with one or more methyl groups,
- R1 can have the meaning given for 9 above, or be
an alkyl group having 1 to 10 carbon atoms or an
cycloalkyl group having 3 to 10 carbon atoms,
- R2 can have the meaning given for 9 above or have
the meaning of R3 below,
R 3 represents an alkyl group having from 1 to 10 carbon atoms
carbon or a cycloalkyl group having from 3 to 10 atoms
of carbon.

 The object of the present invention also relates to the use of said composition for obtaining shaped objects, as well as to the shaped objects obtained with said composition.

The polyamides that may be used in the compositions according to the present invention comprise in particular
polyamides obtained by polycondensation of saturated aliphatic dicarboxylic acids having 6 to 12 carbon atoms with saturated aliphatic bi-primary diamines having from 6 to 12 carbon atoms; the polyamides obtained either by direct homopolycondensation oe-aminoalcanoic acids having a hydrocarbon chain having 4 to 12 carbon atoms, or by hydrolytic opening and polymerization of lactams derived from these acids; the copolyamides obtained from the starting monomers of the abovementioned polyamides, the acid component of these copolyamides possibly being partly terephthalic acid and / or isophthalic acid; and mixtures of such polyamides.These polyamides may be copolyamides based on adipic acid or caprolactam, hexamethylenediamine and fatty acid dimer according to French patents FR-A-2 407 227 and 2 459 810.

 By way of illustration of the polyamides obtained by polycondensation of diacids and diamines, mention may be made, for example, of nylon 4,6 (tetramethylenediamine and adipic acid polymer), nylon 6,6 (hexamethylenediamine polymer and adipic acid), nylon 6.9 (polymer of hexamethylenediamine and azelaic acid), nylon 6.10 (hexamethylenediamine polymer and sebacic acid), nylon 6 12 (hexamethylenediamine and dodecanedioic acid polymer).

 By way of illustration of the polyamino acids which may be suitable, mention may be made of: nylon 4 (4-aminobutanoic acid or x-butyrolactam polymer), nylon 5 (5-amino pentanoic acid or o-amylolactam polymer) ), nylon 6 (ε-caprolactam polymer), nylon 7 (7-amino-heptanoic acid polymer), nylon 8 (capryllactam polymer), nylon 9 (9-amino-nonanoic acid polymer), nylon 10 (amino-10 decanoic acid polymer), nylon 11 (amino-11 undecanoic acid polymer), nylon 12 (amino-12 dodecanol or laurolactam polymer).

 By way of illustration of the copolyamides, mention may be made, for example, of nylon 6,6 / 6,10 (copolymer of hexamethylenediamine, of adipic acid and of sebacic acid), nylon 6,6 / 6 (copolymer of hexamethylenediamine), adipic acid and caprolactam).

 The polyamides which are especially targeted in the present invention are nylon 6,6, nylon 6,10, nylon 6, nylon 6,6 / 6,10 and nylon 6,6 / 6.

 The compositions according to the present invention comprise, by weight, at least 80% of polyamide, preferably at least 90%.

 The polysiloxanes defined above may be cyclic products or linear products.

When cyclic, these polysiloxanes have the formula

m + n can be between 4 and 20 inclusive, with n between 0 and 10 inclusive, the meaning of +, R1, R2 and
R3 being the same as that given above.

dans laquelle
- la signification de , R1, R2, et R3 a été donnée ci-avant
- R4, R5 et R6, identiques ou différents ont la signification donnée pour R1, R2 ou R3, R4 pouvant représenter un groupement hydroxyle. When they are linear, these polysiloxanes have the formula

in which
- the meaning of, R1, R2, and R3 has been given above
- R4, R5 and R6, identical or different have the meaning given for R1, R2 or R3, R4 may represent a hydroxyl group.

t = is between 0 and 100 inclusive
- s = between 1 and 100 inclusive
t and s being chosen so that the viscosity of
the oil at 25 ° C is between 10 and 100,000 mPa.s of
preferably between 50 and 5000 mPa.s.

As examples
alkyl groups for R 1, R 2 and R 3 include methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, 2-ethylhexyl, octyl and decyl radicals.

 cycloalkyl groups for R 1, R 2 and R 3 include cyclopentyl, cyclohexyl, methylcyclohexyl and propylcyclohexyl radicals.

 Preferably in the polysiloxanes used in the compositions according to the present invention 9 = - C6Hs, R1 = - CH3, R2 and R3 when they exist being also groups - CH3.

 The compositions according to the present invention comprise, by weight, from 0.05 to 3%, preferably from 0.1 to 1.5% of the previously defined polysiloxanes.

The polyamide-based compositions according to the present invention may comprise, in known manner, various adjuvants, such as, for example, pigments, dyes, stabilizers, lubricants.
They may optionally comprise other polymers, such as, for example, an ethylene-propylene-based copolymer optionally grafted with maleic anhydride.

 The compositions according to the present invention may be prepared by simply mixing the various constituents in any appropriate manner to obtain a homogeneous composition. Preferably, the various constituents are mixed in the form of powder or granules by first cold-working a premix in a conventional mixer and then homogenizing the assembly by hot-kneading in a hot-melt extruder. one or more screws. At the end of this treatment, rods are obtained which are cooled for example with water and then cut into granules, the latter possibly being able to be subjected to drying.

 The compositions according to the invention can be converted into finished or semi-finished articles having a good flame resistance, by applying the usual injection or extrusion techniques. Although the fields of use of these articles are very varied, such articles are particularly suitable for uses in industries related to electricity (electrical, electronic, household appliances, radio, automotive).

 The compositions according to the present invention also make it possible to make articles by spinning or filming.

 Examples 1 to 3 show that the compositions according to the present invention (Examples 2 and 3) make it possible to obtain objects that are resistant to the flame, while being obtained at a high production rate.

Examples 1 to 3
Description of the raw materials used
polyamide 66: polyhexamethylene adipamide of viscosity index 137 ml / g determined according to the ISO R 307 standard, 1977 edition, on the part soluble in 90% formic acid,
- powder TG: ethylene glycol polyterephthalate powder, viscosity index 70 ml / g, determined according to ISO 1628 part 5 editions 1986, on a soluble part in a mixture 50/50 by weight of phenol and 1,2-dichlorobenzene,
- aluminum tristearate: a product marketed under the name of
HARO GEL ALT by HMGEN CHEMIE BV,
silicone oils: polymethylphenylsiloxane oils marketed under the name RHODORSIL 550V100 and 641V200 by
RHONE-POULENC, these oils respectively having viscosities of 100 mPa.s and 200 mPa.s.

Preparation of the compositions according to Examples 1 to 3
Each composition is prepared as follows
The PA66 and the chosen silicone oil are mixed (in quantities, by weight, corresponding to the table below, according to the examples) for 10 minutes (except in Example 1 which does not contain silicone oil), at room temperature. In a MORITZ blender, the aluminum tri-stearate and the TG powder are incorporated, and the mixture is stirred for a further 10 minutes.

The premix obtained is then kneaded in the molten state in a PRODEX extruder-degasifier having a screw of diameter D equal to 65 mm and of length equal to 24 D. The screw used is a cylindro-conical screw having a suitable profile. for the work of polyamides
This extruder is equipped with a die with 2 holes 5 mm in diameter.

The extrusion conditions are as follows
- temperature 305-275 ° C
- absolute degassing pressure 150 mbar
- speed of the screw: 48 RPM.

 The product leaving the die is collected in the form of rods, cooled by passing through a bath of cold water, then it is granulated and dried. It is then a "molding powder".

Tube tube test
The test makes it possible to measure the increase in the rates obtained with the compositions according to the present invention (that is to say the reduction in the minimum cooling time of a part injected into the mold so that it can be demolded without deformation notorious) is carried out in a mold whose shape makes it possible to inject a cylindrical tube 60 mm long, whose outside diameter is 27 mm, whose internal diameter is 25 mm and having 6 identical internal fins evenly distributed in the tube over its entire length, 5 mm wide and 1 mm thick. Any section of this cylindrical tube made perpendicular to its longitudinal axis is shown in the attached figure (scale 4). This test is hereafter called "finned tube test", or moldability test.

This test is performed on a KRAUSS MAFFEI 25/50 press. Each composition prepared above in the form of a "molding powder" is injected into the press under the following conditions:
. screw speed: 300 RPM
. dosing time: 1.8 s
sheath temperature: 250-260-270-280 "C
mold temperature: 80 "C
injection pressure: 160 bar
holding pressure: 140 bar
cycle time: 14 s
The part is ejected at the end of the cycle.

 The cooling time is arbitrarily set at 10s initially, then decreased by seconds in seconds. Five pieces are molded for each cooling time. There is a cooling time t for which no ejected part is deformed, while one second less (that is to say for a cooling time equal to tl second) is sufficient to cause the permanent deformation of at least one molded part. It is the time t which is the answer to the moldability test called "Test of the finned tube".

 Preparation of specimens for the measurement of the UL 94-V2 test.

With the compositions prepared in Examples 1 to 3 (see table) by operating as described above, specimens having the dimensions 127 × 12.7 × 0.8 mm are produced by molding on a press
BILLON H 220 (85 T), the parameters being:
jacket temperature: 260/270/280/285 "C,
. mold temperature: 80 ° C,
. screw speed: 250 RPM,
. locking pressure: 140 bar,
. injection pressure: 60 bar,
. holding pressure: 50 bar,
. injection time + hold: 5 seconds,
. cooling time in the mold: 15 seconds,
. cycle time: 28 seconds.

<tb><SEP> composition <SEP> EX <SEP> 1 <SEP> EX <SEP> 2 <SEP> EX <SEP> 3
<tb><SEP> PA <SEP> 66 <SEP> 100 <SEP> 100 <SEP> 100
<tb> aluminum tristearate <SEP><SEP> 0.25 <SEP> 0.25 <SEP> 0.25
<tb> powder <SEP> TG <SEP> 0.2 <SEP> 0.2 <SEP> 0.2
<tb> oil <SEP> silicone <SEP> 550V <SEP> 100 <SEP> 0 <SEP> 0.5 <SEP> 0
<tb> oil <SEP> silicone <SEP> 641V <SEP> 200 <SEP> 0 <SEP> 0 <SEP> 0.5
<tb><SEP> RESULTS <SEP>
<tb> Test <SEP> tube <SEP> to <SEP> fins <SEP> 7 <SEP> 2 <SEP> 2
<tb><SEP> (in <SEP> seconds)
<tb> UL94 <SEP> V <SEP> V2 <SEP> V2 <SEP> V2
<Tb>

Claims (9)

CLAIMS of carbon. carbon or a cycloalkyl group having from 3 to 10 atoms - R3 represents an alkyl group having from 1 to 10 atoms of the meaning of R3 below, - R2 may have the meaning given for above or have a cycloalkyl group having from 3 to at 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms or a - R 1 may have the meaning given for above, or may be - represents a phenyl group optionally substituted by one or more halogen atoms and / or with one or more methyl groups,  1 "- Composition based on polyamide characterized in that it comprises at least one polysiloxane consisting essentially of R1SiO2 / 2 units with optionally R2R3SiO2 / 2 units in which  2 "- Composition according to claim 1, characterized in that the polysiloxane is cyclic or linear.

 3 - Composition according to any one of the preceding claims, characterized in that the polysiloxane is cyclic and has the formula R3 being the same as that given above.  m t n may be between 4 and 20 inclusive, with n between 0 and 10 inclusive, the meaning of X, R1, R2 and  preferably between 50 and 5000 mPa.s.  the oil at 25 ° C is between 10 and 100,000 mPa.s of  t and s being chosen so that the viscosity of  - s = between 1 and 100 inclusive  t = is between 0 and 100 inclusive  R4, R5 and R6, which are identical or different, have the meaning given for R1, R2 or R3, R4 possibly representing a hydroxyl group  - the meaning of, R1, R2, and R3 has been given above  in which

 4 "- Composition according to any one of claims 1 or 2, characterized in that the polysiloxane is linear and in that it has formula  5 - Composition according to any one of the preceding claims wherein the polysiloxane comprises a plurality of groups CH3, C6H5Si 02/2.  6 "- Composition according to any one of the preceding claims characterized in that it comprises by weight, at least 80% of polyamide, preferably at least 90%.  7 "- Composition according to any one of the preceding claims characterized in that it comprises, by weight, from 0.05 to 3%, preferably from 0.1 to 1.5% of the polysiloxanes defined above.  8 "- Use of the composition according to any one of the preceding claims as a molding material for obtaining shaped articles having a good flame resistance.  9 "- shaped articles such as, especially clamps for electrical son or cables, obtained with the composition according to any one of the preceding claims.