NO173739B - GORGEOUS COPOLYMER, ITS MANUFACTURING AND AN ALLOY FOUND USED BY THE POLYMER - Google Patents

Abstract

A grafted copolymer consisting of at least one monoaminated polyamide oligomer and an α-mono-olefin polymer or copolymer grafted with a monomer which can react with the amine functions of the oligomer. The compounds are prepared by radical polymerization of the monomer on the copolymer with subsequent addition of the oligomer. grafted copolymers are used as a means of making at least two incompatible thermoplastic polymers compatible with each other in the manufacture of composite materials.

Description

The present invention relates to a graft copolymer based on an α-mono-olefin, the preparation of the polymer and an alloy obtained using the polymers as a means of making at least two incompatible thermoplastic polymers compatible.

In certain specific mixtures, it is known to make two incompatible polymers compatible by joining them with a third polymer which is partially compatible with one or the other of the polymers. For this purpose, for example, various third polymers have been proposed for the polypropylene-polyamide mixture: In JP 70-030943, a preparation comprising polypropylene, polyamide and polypropylene grafted with maleic anhydride has been proposed;

In JP publ. 59-149940 requires a preparation containing polypropylene, polyamide and a copolymer ethylene-propylene, grafted with maleic anhydride;

FR-PS 2,107,538 describes a preparation made of polypropylene and polyamide reinforced with glass fibers which has been made compatible by adding a copolymer of propylene and α-olefin grafted with polyamide chains. This graft copolymer is obtained by polycondensation of an amino acid in the presence of propylene copolymer previously grafted with maleic anhydride;

In JP publ. 60-233131 describes the preparation of a graft copolymer to make a mixture of polypropylene and polyvinyl chloride compatible. This graft copolymer is obtained by reacting a polypropylene modified with 2 to 20 wt% maleic anhydride, with a polymethyl methacrylate having a terminal hydroxy group.

The present invention primarily relates to new graft copolymers of at least one monoaminated oligomer of polyamide and a polymer or copolymer of an α-mono-olefin which is grafted with a monomer that can react with an amine function to the monoaminated oligomer of polyamide.

The invention also relates to a method for producing this graft copolymer. This is preferably carried out by radical grafting onto a polymer chain containing parts derived from an α-mono-olefin, a monomer capable of reacting with an amine function and then by addition of the monoaminated oligomer of the polyamide onto the grafted copolymer.

The invention finally relates to an alloy of at least two incompatible thermoplastic copolymers which have been made compatible by the addition of compounds as described above.

According to the invention, the graft copolymer corresponds to the formula Aa Mb <X>c Pd there

Aa Mtø corresponds to a thermoplastic copolymer strain; and

Xc and Pa correspond to grafted polymers on the (co)polymer backbone; and the copolymer is characterized by that

A is a moiety derived from an α-mono-olefin containing 2

to 8 carbon atoms and is preferably partly derived from

propylene;

M is selected from groups consisting of:

moieties derived from an α-mono-olefin containing 2 to 8

carbon atoms and preferably ethylene derivatives,

moieties derived from several α-mono-olefins as defined above and which may be simple mixtures together or be copolymerized in a statistical manner or sequential manner, and preferably where one of the α-mono-olefins is

ethylene,

moieties derived from a monomer which may be polymerized with one of the α-mono-olefins as defined above, e.g.

an alkyl acrylate, wherein M is not a diene;

in that the parts A and M which make up the copolymer stock are copolymerized in a statistical manner or in a sequential manner

or simply mixed;

X is a moiety derived from a monomer which may be radically polymerized on a homo- or copolymer of α-mono-olefin and with a function which may react with an amine moiety;

P is derived from an oligomer of polyamide with the formula:

there:

f is a number between 3 and 11; g is a number between 5 and 80 and preferably between 15 and 55; R 5 is hydrogen or a linear or branched alkyl group containing up to 20 carbon atoms; Rfc is a linear or branched alkyl or alkenyl group with up to 20 carbon atoms, a cycloaliphatic optionally saturated residue, an aromatic residue or a combination thereof; a, b, c and d are numbers corresponding to the following definitions tions: a is between 0 and 5000 and preferably between 350 and 2000; the sum a + b is between 350 and 45,000 and preferably between 500 and 10,000; c is chosen so that the weight ratio between the monomer X which is grafted onto the (co)polymer backbone and the copolymer grafted with X is between 500 ppm and 10% and preferably below 2%, and preferably between 5000 ppm and 1.5%;

d is not 0 and below or equal to c and preferably at least equal to

0.3 c.

By the (co)polymer stem with the formula: Aa M]-, where a, b, A and M are as indicated above, is meant any copolymer compound with the parts a and b, derived from polymerized monomers in a statistical or sequential manner, possibly any mixture of polymers obtained by separate polymerizations of monomers from which parts A and B are derived.

This copolymerization or mixing can be carried out in a manner known per se.

As an example, mention should be made of the copolymerization of propylene and α-olefin in the presence of a ZIEGLER catalyst or a coordination catalyst.

As mentioned above, the invention also relates to a method for producing a graft copolymer as described in the introduction and this method is characterized by the fact that it comprises: a radical grafting onto the copolymer stem of a monomer which

reacts with an amine function;

then addition of a polyamide oligomer on it

pre-grafted copolymer.

The monomer X which is radical-grafted onto the copolymer backbone and which has a function that can react with an amine function can in particular correspond to one of the following formulas:

there:

R 1 and R 2 are hydrogen or a linear or branched alkyl chain with up to 8 carbon atoms, at least one of which

the symbols mean hydrogen;

R 3 is hydrogen or a linear or branched alkyl group

containing up to 10 carbon atoms; and

R4 is a linear or branched alkenyl group containing

up to 12 carbon atoms.

The monomers X which are preferred are citraconic, fumaric, mesaconic, 3-allyl succinic and especially maleic anhydride.

The grafting of the monomer X onto the copolymer stem, which is carried out according to a radical mechanism, takes place in the presence of a radical generator which can be dicumyl or benzoyl peroxide or -2,5-dimethyl-2,5-di(tertbutylperoxy)hexane.

Usually this compound is used in an amount of 2.5. 10-4 to 4. 10"2, calculated on the weight of the copolymer.

The radical grafting of the monomer X onto the copolymer stock can be carried out in the molten state or in a solution, in a solvent, of the copolymer stock. Examples of such solvents include toluene, xylene and chlorobenzene.

In the technique of grafting in solution is particularly recommended when it comes to achieving a degree of grafting above 1.5 # (the weight ratio between grafted monomer X and the copolymer stock grafted with X).

The copolymer stock, the monomer X and the radical polymerization initiator are introduced into a solvent for the copolymer. The whole is brought to a temperature so that a thermal decomposition of the radical initiator takes place to carry out the grafting reaction. Generally speaking, the duration of this reaction is between 0.5 and 10 times and preferably between 1 and 4 times the duration of the half-life of the radical initiator at the reaction temperature.

In general, the decomposition temperature for the thermal radical initiator is between 90 and 200°C and preferably 110 and 140°C.

The radical grafting technique in the molten state of the monomer X on copolymer strains is particularly suitable when one wants to achieve a degree of grafting between 500 ppm and 1.5%.

Radical grafting in the molten state consists in mixing the copolymer stock with the selected amounts of the monomer X and the radical initiator, for example in an extruder. The mixture is brought to a temperature which is generally between 170 and 250°C and preferably between 180 and 200°C.

The residence time of the molten material in the extruder is usually chosen between 15 seconds and 3 minutes and preferably it is between 40 and 80 seconds.

The degree of grafting for the monomer X on the copolymer stock can be measured by dosing the anhydride functions by infrared spectrophotometry.

The oligomeric monoaminated polyamide P with the formula is then added to the graft copolymer:

where f, g, E5 and Rfc are as stated above.

This monoaminated oligomer of polyamide can be obtained by polycondensation of an amino acid with the formula:

or by polyaddition of a lactam of the formula: where f has the above meaning, in the presence of a monofunctional polymerization inhibitor of the formula:

where R 5 and R f have the meaning given above.

The amino acid or lactam monomers which are preferred for the synthesis of the monoaminated oligomer according to the invention are selected from among caprolactam, 11-aminoundecanoic acid or dodecalactam.

The preferred monofunctional polymerization inhibitors are laurylamine and oleylamine.

The polycondensation as stated above takes place according to methods known per se, for example at a temperature generally between 200 and 300°C, under reduced pressure or under an inert atmosphere, while stirring the reaction mixture.

The average chain length of the oligomer is determined by the initial molar ratio between the polycondensable monomer or lactam and the monofunctional polymerization inhibitor.

For calculating the average chain length, one molecule of chain length limiting agent is usually calculated per oligomeric chain.

Addition of the monoaminated oligomer of the polyamide to the copolymer stock which is grafted at a monomer X takes place by reacting an amine function on the oligomer with at least one anhydride or acid function from the grafted copolymer. Thus, amide or imide bonds are created.

The addition of the oligomer P to the grafted copolymer stem is preferably carried out in a molten state. One can thus mix the oligomer and the copolymer in an extruder at a temperature which is generally between 230 and 250°C. The average residence time for the molten material in the extruder can be between 15 seconds and 5 minutes and is preferably between 1 and 3 minutes.

Addition of the oligomer to the graft copolymer stock is evaluated by selectively extracting the oligomers of free polyamide, i.e. those that have not reacted to give the final graft copolymer.

The copolymers of the grafted α-mono-olefins according to the invention show the following advantages in relation to the polymers known in the literature: You can control the degree of grafting for the oligomer of poly the amide on the graft copolymer and thus determine the structure of the coded copolymer;

One can adjust and control the average molecular weight of the monoaminated oligomer of the polyamide. Thus, the average molecular weight of the oligomer of the polyamide is a determining factor for the effect and efficiency of the graft copolymer according to the invention as a compatibility-promoting agent for alloys of non-compatible

polymers;

The coded copolymers according to the invention do not exhibit any reactive chain ends in terms of polycondensation, during the mixing of the components of the alloy with the grafted copolymer according to the invention, the chain ends do not react in an uncontrolled manner.

The graft copolymer according to the invention allows in particular to combine in a homogeneous way at least two thermoplastics between incompatible polymers, but where at least one is compatible with the oligomer of the polyamide that constitutes copolymers and the other is compatible with the copolymer stem,

The graft copolymer can be incorporated in the usual manner into the thermoplastic resin mixture in a molten state in a mixing apparatus. The amount of copolymer introduced can be between 0.1 and 30% and is preferably between 5 and 15% by weight, calculated on the weight of the mixture of thermoplastic resins.

As an example, polymers or thermoplastic resins which are compatible with the oligomers of the polyamide entering into the composition of the graft copolymer should be specifically mentioned. aliphatic polyamides such as polyamide 6, 11 or 12; semi-aromatic polyamides and especially those as defined in FR-PS 1,588,130, 2,324,672 and 2,575,756, EP-PS 53,876

or JP-PS 60,217,237 and 59,015,447;

sequenced polyether ester amides or polyether block amides and especially those products described in US-PS

4,332,920 and 4,331,786;

hydrolyzed vinyl acetate-ethylene copolymers;

resins having phenolic elements such as polyparavinylphenol.

The term polymers also means copolymers to the extent that the amount of parts that are compatible with the copolymer is sufficient to preserve compatibility.

The term polymers also refers to the mixture of polymers (or copolymers) with various additives such as impact modifiers, mineral fillers, glass fibres, pigments and so on.

As examples of compatible thermoplastic polymers with the copolymer stem, polypropylene, polyethylene or ethylene-propylene copolymers can be mentioned in particular.

Thanks to the compatibilizer according to the invention, it is possible to realize improved alloys such as:

Polyamide-6 polypropylene

Polyamide-6 polyethylene

Polyamide-6 -ethylene/propylene copolymer Polyamide-11 or 12 -polypropylene or polyethylene

or ethylene/propylene copolymer Hydrolyzed ethylene-vinyl acetate copolymer

- polypropylene or polyethylene or ethylene/propylene copolymer Polyparavinylphenol - polypropylene or polyethylene

or ethylene/propylene copolymer Polyether block-amide -polypropylene or polyethylene

or ethylene/propylene copolymer Semi-aromatic polyamide - polypropylene or polyethylene

or ethylene/propylene copolymer.

As mentioned at the outset, the invention also relates to alloys of at least two incompatible thermoplastic polymers which have been made compatible by the addition of the compounds according to the invention.

The compatibility achieved for the graft copolymer according to the invention is clearly shown by electron microscopy and by the mechanical properties of the product resulting from mixing the incompatible thermoplastic polymers.

The morphology of a mixture of thermoplastic polymers without the graft copolymer according to the invention, examined by electron microscopy, generally appears in the form of large nodules of one polymer incorporated into the matrix consisting of the other polymer, as the addition between the nodules and the matrix is virtually non-existent. Addition of the graft copolymer forces a significant degradation of the nodule size. One also observes a strong addition between the visible phases with a covering of the nodules by the matrix. Under these conditions, what can be called an alloy is formed by the assimilation of a metallurgical structure that clearly differs from simple mixtures.

The mechanical properties of such thermoplastic alloys are at least equal to those of the components, seen in relation to the volume fraction of each component, and in certain cases better than what should be expected on the basis of the two components, for example with regard to elasticity.

In contrast to the alloys according to the invention, simple mixtures of the same incompatible polymers among themselves without the use of the graft copolymer of the invention exhibit mechanical properties which are generally closer to that of the worst component.

The following examples shall illustrate the invention.

Example 1:

A. - Synthesis of the graft copolymer strain X.

Into a WERNER extruder is continuously fed a mixture which, on a weight basis, comprises 100 parts of propylene-ethylene sequence copolymer (containing 12 weight-# of ethylene with a melt index of 5 and a melting point of 163°C), 1.6 parts of maleic anhydride and 1.7 parts of 2,5- dimethyl 2,5-di(tertbutylperoxy)hexane, dissolved in one part chlorobenzene.

The whole thing is brought to 200°C and the speed of rotation of the screw is set to 100 revolutions per minute. minute.

One works to volatilize the mixture before the inlet to the nozzle in order to extract unreacted chlorobenzene and maleic anhydride.

At the outlet of the nozzle, a sample of grafted polymer is withdrawn, which is dissolved in xylene and then precipitated from acetone for purification. When dosing the anhydride functions by IR spectrophotometry, 1.16 wt-56 grafted anhydride is determined.

With gel permeation chromatography, a number average molecular weight equal to 32,000 is determined.

B. - Synthesis of polyamide oligomer P

31 kilograms of caprolactam, 0.91 kilograms of laurylamine and 3.5 liters of water are added to a stainless steel reactor of 100 litres.

The reactor is heated in a closed state for 2 hours to 250°C after flushing it with nitrogen and while stirring at 35 revolutions per minute. minute. A relaxation to atmospheric pressure is then carried out over the course of an hour.

After a nitrogen purge of the reactor for 15 minutes, the oligomer is completely immersed in water, drained, washed with water at 80°C and then dried for 16 hours under reduced pressure at 80°C.

In this way, an oligomer of polyamide is obtained whose number average molecular weight is 5700, determined by potentiometric dosing of the terminal amine functions.

C. - Preparation of graft copolymer

In a WERNER ZSK30 extruder, a mixture comprising, by weight, 59.8 parts of grafted copolymer stock as described under A and 40.2 parts of oligomer as described under B is mixed in a molten state.

The whole thing is brought to 240°C.

The average residence time for the mixture in the extruder is approx. 3 minutes.

At the exit of the extruder, a sample of the material is removed, which is then introduced into an extraction device of the KUMAGAWA type.

The polyamide oligomers that have not reacted with the anhydride functions in the maleinated copolymer are then selectively extracted with formic acid. In this way, a degree of condensation for the polyamide oligomer on the graft copolymer is determined at 65%.

The copolymer thus obtained can be represented by the equation: <A>663 <M>136 <x>3.78 p2 .45

where A is a moiety derived from propylene

M is a moiety derived from ethylene

X is a moiety derived from maleic anhydride

P is a caprolactam oligomer with Mn = 5700.

Example 2:

A WERNER extruder is continuously fed a mixture which, on a weight basis, comprises 3 parts polypropylene, 57 parts polyamide 6 and 10 parts maleinized copolymer stock as described in example 1.A (sample 1).

Along the sleeve, the temperature is between 255 and 270°C. The rotation speed of the screw is 150 revolutions per minute and the amount of material is 20 kg. per hour.

Under the same conditions, a mixture is extruded which, on a weight basis, contains 33 parts polypropylene, 57 parts polyamide 6 and 10 parts graft copolymer as described in example 1.C (sample 2).

A comparison mixture is also prepared under the same conditions which, on a weight basis, contains 36.7 parts polypropylene and 36.3 parts polyamide 6 (sample 3).

For samples 1, 2 and 3, the polypropylene used is a homopolymer of propylene with a melting index equal to 3 and a melting point of 166°C and the polyamide 6 used is a homopolymer of caprolactam with a melting point of 218°C.

Samples 1, 2 and 3 are injection molded into a plate shape with dimensions 100 mm X 100 mm X 3 mm, in which iso 1/2 cuts are made in accordance with NFT 51034.

The test pieces are cut in the injection direction (test pieces A); the others are cut perpendicular to this (test pieces B). Test pieces are also cast with the samples according to the norm given by the "Institut Francais du Caoutchouc", (test pieces C).

Test pieces Å, B and C are assessed for tensile elongation in accordance with NFT 51034.

The test pieces of sample 3 (comparison) are extremely brittle: they break at 5 to 6% elongation, this indicates a rough and inhomogeneous morphology because there is a lack of adhesion between the two constituents of the test piece comparison 3.

Samples A, B and C to sample 1 behave differently: samples A and B are somewhat more brittle than sample C, this corresponds to an inhomogeneity in the sample as well as an orientation sensitivity.

A homogeneous ductile behavior is observed for the three types of test pieces from sample 2: this indicates a good homogeneity for sample 2 and further little sensitivity to transformation and orientation.

A CHARPY impact test is also carried out at ambient temperature on samples 1 and 2 after they have been injection molded into rods.

For sample 1, a destruction rate of 60% is observed, while for sample 2 no beam was destroyed.

Example 3:

A. A V/ERNER ZSK30 extruder is continuously fed a mixture containing, on a weight basis, 100 parts of sequential copolymer ethylene-propylene (containing 12 wt-# ethylene with a melt index of 5 and a melting point of 136°C), 1.5 parts of maleic anhydride and 1.7 parts 2,5 dimethyl 2,5 di(tertbutylperoxy)-hexane, dissolved in 1 part chlorobenzene. The extrusion conditions and purification are identical to those given in Example 1.A.

The amount of anhydride functionality, determined by IR spectrophotometry of a sample of the grafted copolymer indicated that 1.02 wt-# of anhydride is grafted.

The number average molecular weight Mn, determined by gel permeation chromatography, is 19,700.

B. A monoaminated polyamide oligomer is prepared under the same conditions as described in example 1.B with a weight ratio caprolactam:laurylamine equal to 15.7. The number average molecular weight Mn for the oligomer is 2,800. C. In a WERNER ZSK30 extruder, a mixture is mixed in a molten state and under the same conditions as described in example 1.C, a mixture comprising, on a weight basis, 77 parts of graft copolymer as described above and 23 parts of polyamide oligomer as described previously.

After the extrusion, the degree of condensation of the oligomer on the grafted copolymer strain is measured under the same conditions as described above in example 1.C and the value is 65.8%.

The graft copolymer obtained can be represented by the formula: <Å>409 <M>84 <X>2.05 <P>1.35

where A means a polyethylene-derived moiety

M means an ethylene-derived moiety

X means a maleic anhydride-derived moiety

P means a caprolactam oligomer-derived part with average molecular weight = 2800.

Example 4:

A mixture by weight comprising 50 parts of polypropylene and 50 parts of hydrolyzed ethylene vinyl acetate copolymer (EVOH) is brought to 220°C and tube mixed in a BRABENDER plastograph for 30 minutes at an agitation rate of 50 revolutions per minute (Sample 4).

A mixture comprising, on a weight basis, 49 parts polypropylene, 49 parts EVOH and 2 parts maleinized ethylene-propylene copolymer stock as described in example 3.A, is mixed under the same conditions as above (sample 5).

One also prepares under the same conditions a mixture which, on a weight basis, contains 49 parts polypropylene, 49 parts EVOH and 2 parts graft copolymer as described in example 3.C (sample 6).

For samples 4, 5 and 6, the polypropylene used has a melting index equal to 5 and a melting point equal to 166° C and the EVOH used is such that the amount of ethylene is 38 mol%.

Samples 4, 5 and 6 are then examined with scanning electron microscopy at a magnification equal to 2500.

Examination of sample 4 shows that the polymers are very poorly compatible: one can distinguish completely separate EVOH nodules whose diameter varies from 11 to 27 pm in the matrix of polypropylene; furthermore, it is observed that the adhesion between these nodules of EVOH and the polypropylene matrix is very poor.

The examination of sample 5 suggests a rather coarse morphology: EVOH nodules with a diameter between 5.7 and 7 pm were determined, whose adhesion to the polypropylene matrix is poor.

An examination of sample 6 suggests a very fine morphology which is characterized by nodules with a diameter between 1.7 and 2.8 pm and whose adhesion to the polypropylene matrix is very good.

Example 5:

A mixture by weight comprising 50 parts polypropylene and 50 parts polyparavinylphenol (PPVP) is brought to 200°C and mixed in the tube of a BRABENDER plastograph for 15 minutes at a stirring rate of 50 revolutions per minute. minute (sample 7).

A mixture containing, on a weight basis, 49 parts of propylene, 49 parts of polyparavinylphenol and 2 parts of maleinized ethylene-propylene copolymer as described in example 3.A, is mixed under the same conditions as described above (sample 8).

One also prepares under the same conditions a mixture which, on a weight basis, contains 49 parts polypropylene, 49 parts polyparavinylphenol and 2 parts graft copolymer as described in example 3.C (sample 9).

For samples 7, 8 and 9, the polypropylene used has a melting index of 5 and a melting point of 166°C and the polypara-vinylphenol is an oligomer whose weight average molecular weight is 4000 and whose melting point rises from 160 to 200°C.

Samples 7, 8 and 9 are then examined by scanning electron microscopy at a magnification of 2,500.

An examination of sample 7 shows a gross morphology where one finds localized discontinuous phases or ovoid nodules of PPVP with a mean diameter equal to 30 pm, dispersed in a matrix of PP. The total incompatibility between the two polymers is shown by observing the fracture surfaces.

An examination of sample 8 shows a better dispersion of PPVP in PP. The average particle size for the PPVP nodules dispersed in the PP matrix is around 10 pm. The adhesion between the phases is not improved compared to sample 7.

An examination of sample 9 suggests a fine morphology characterized by PPVP nodules with an average diameter equal to 2 µm, dispersed in the PP matrix, and whose adhesion to this matrix is greatly improved compared to that obtained in samples 7 and 8 .

Example 6:

A mixture by weight comprising 50 parts polypropylene and 50 parts polyetheresteramide is brought to 200°C and mixed in a BRABENDER plastograph for 15 minutes at a stirring rate of 50 revolutions per minute. minute (sample 10).

A mixture by weight comprising 49 parts PP, 49 parts polyether esteramide and 2 parts maleinized ethylene propylene copolymer as described in example 3.A is mixed under the same conditions as above (sample 11).

A mixture comprising 49 parts PP, 49 parts polyetheresteramide and 2 parts graft copolymer is also prepared under the same conditions as described in example 3.C (sample 12).

For samples 10, 11 and 12, the PP used had a melt index equal to 5 and a melting point of 166°C and the polyetherester amide is obtained by sequence copolycondensation of a,co dicarboxylated polyamide 12 with Mh = 600 and sequences of a,to dihydroxylated polytetramethylene glycol with Mh = 2000.

Samples 10, 11 and 12 are then examined by scanning electron microscopy under a magnification of 2,500.

An examination of sample 10 suggests a particularly coarse morphology characterized by a three-dimensional mesh.

An examination of sample 11 shows no improvement in adhesion nor reduction of the width of the three-dimensional network compared to sample 10.

When examining sample 12, a less coarse morphology is observed than that in samples 10 and 11. The morphology in sample 12 is no longer characterized by a three-dimensional network but by dispersion of polyetheresteramide nodules in a polypropylene matrix.

Example 7

A mixture comprising, by weight, 50 parts polypropylene and 50 parts semi-aromatic amorphous polyamide is brought to 220°C and mixed in a BRABENDER plastograph for 30 minutes at a stirring rate of 50 revolutions per minute. minute (sample 13).

A mixture comprising, on a weight basis, 49 parts polypropylene, 49 parts semi-aromatic amorphous polyamide and 2 parts maleinized ethylene propylene copolymer as described in example 3. A is mixed under the same conditions as above (sample 14).

One also prepares and under the same conditions a mixture which, on a weight basis, contains 49 parts polypropylene, 49 parts semi-aromatic amorphous polyamide and 2 parts coded copolymer as described in example 3.C (sample 15).

For samples 13, 14 and 15, the polypropylene used has a melting index equal to 5 and a melting point equal to 166° C and the semiaromatic amorphous polyamide used is based on terephthalic acid and (2,2,4- and 2,4,4)- trimethyl 1,6-diamino hexane.

Samples 13, 14 and 15 are then examined by scanning electron microscopy at a magnification of 2500.

An examination of sample 13 suggests an incompatibility between the two polymers: one can distinguish the nodules of semi-aromatic amorphous polyamide whose average diameter is 30 pm, dispersed in the matrix of polypropylene. Furthermore, there is no adhesion between the polyamide nodules and the PP matrix.

Sample 14 exhibits a very coarse morphology; the polyamide nodules with an average diameter of 5 pm are dispersed in the PP matrix, the adhesion between nodules and matrix is medium.

An examination of sample 5 suggests a very fine morphology which is characterized by polyamide nodules with an average diameter of 3.3 pm and whose adhesion to the PP matrix is good.

Example 8:

A mixture comprising, on a weight basis, 50 parts polypropylene and 50 parts semi-aromatic amorphous polyamide is brought to 280° C and mixed in a HAAKE plastograph for 20 minutes at a stirring rate of 50 revolutions per minute. minute (sample 16). A mixture containing, on a weight basis, 49 parts polypropylene, 49 parts semi-aromatic amorphous polyamide and 2 parts maleinized ethylene propylene copolymer as described in example 3.A, is mixed under the same conditions as above (sample 17).

One also prepares under the same conditions a mixture which, on a weight basis, contains 49 parts polypropylene, 49 parts semi-aromatic amorphous polyamide and 2 parts graft copolymer as described in example 3.C (sample 18).

For samples 16, 17 and 18, the polypropylene used has a melting index of 5 and a melting point of 166°C, the polyamide used is based on isophthalic acid, 4,4'-diamino 3,3'-dimethyl-dicyclohexylmethane and lauryl-lactam .

Samples 16, 17 and 18 are then examined by scanning electron microscopy at a magnification of 2500.

An examination of sample 16 suggests an incompatibility between the two polymers, one can distinguish polyamide nodules whose average diameter is 20 pm, dispersed in the PP matrix. Furthermore, there is no adhesion between polyamide nodules and matrix.

An examination of sample 17 shows a very rough morphology, the polyamide nodules with an average diameter of 10 pm are dispersed in the PP matrix, adhesion between nodules and matrix is medium.

An examination of sample 18 suggests a very fine morphology of polyamide nodules with a mean diameter of 3.5 and whose adhesion to the matrix is good.

Example 9:

A WERNER extruder is continuously fed a mixture which, on a weight basis, comprises 26 parts polypropylene, 67 parts polyamide 6 and 7 parts maleinized ethylene propylene copolymer as described in example 3.Å (sample 19).

Along the sheath, the material temperature is kept between 260 and 290°C. The rotation speed of the screw is 150 revolutions per minute and the amount of material is 20 kilos per hour.

Under the same conditions, a mixture is extruded which, on a weight basis, comprises 26 parts polypropylene, 67 parts polyamide 6 and 7 parts graft copolymer as described in example 1.C (sample 20).

A comparative mixture containing 32.7% polypropylene and 67.3% polyamide 6 by weight is also prepared under the same conditions.

For samples 19, 20 and 21, the polypropylene used is a polypropylene homopolymer with a melting index of 12 and a melting point of 166°C, polyamide 6 is a homopolymer of caprolactam with a melting point of 218°C.

Samples 19, 20 and 21 are injection molded into the shape of bars with dimensions 127 mm X 12.7 mm X 6.4 mm and their resistance to IZOD impact is assessed according to the ISO standard at 23 and at 40°C. The results of this evaluation can be found in

the table below.

Claims (8)

1. Grafted copolymer, corresponding to the formula: Aa M^ Xc P^ where: Aa M^ corresponds to a -thermoplastic (co)polymer strain; Xc and P(j) correspond to grafted polymers on the (co)polymer stem; characterized in that A is a part derived from an α-mono-olefin containing 2 to 8 carbon atoms and is preferably partly derived from propylene; M is selected from groups consisting of: moieties derived from an α-mono-olefin containing 2 to 8 carbon atoms and preferably ethylene derivatives, moieties derived from several α-mono-olefins as defined above and which may be simple mixtures together or be copolymerized in a random or sequential manner, and preferably where one of the α-mono-olefins is ethylene, parts derived from a monomer which may be polymerized with one of the α-mono-olefins as defined above, for example an alkyl acrylate, where M is not a diene; in that the parts A and M which make up the copolymer stem are copolymerized in a random manner or sequential manner or simply mixed; X is a moiety derived from a monomer which may be radical- polymerized on a homo- or copolymer of α-mono-olefin and having a function which can react with an amine moiety; P is derived from an oligomer of polyamide with the formula: there: f is a number between 3 and 11; g is a number between 5 and 80 and preferably between 15 and 55; R 5 is hydrogen or a linear or branched alkyl group containing up to 20 carbon atoms; Rfc is a linear or branched alkyl or alkenyl group with up to 20 carbon atoms, a cycloaliphatic optionally saturated residue, an aromatic residue or a combination thereof; a, b, c and d are numbers corresponding to the following definitions tions: a is between 0 and 5000 and preferably between 350 and 2000; the sum a + b is between 350 and 45,000 and preferably between 500 and 10,000; c is chosen so that the weight ratio between the monomer X which is grafted onto the (co)polymer backbone and the copolymer grafted with X is between 500 ppm and 10 # and preferably below 2 10 , and most preferably between 5000 ppm and 1.5 $; d is not 0 and below or equal to c and preferably at least equal to 0.3 c. 2. Graft copolymer according to claim 1, characterized in that the monomer from which X is derived is selected from compounds with the formula: there: R 1 and R 2 are hydrogen or a linear or branched alkyl chain of up to 8 carbon atoms, at least one of the symbols being hydrogen; R 3 is hydrogen or a linear or branched alkyl group containing up to 10 carbon atoms; and R4 is a linear or branched alkenyl group containing up to 12 carbon atoms. 3. Process for producing a graft copolymer according to claims 1 and 2, characterized in that it comprises: a radical grafting onto the copolymer stem of a monomer which reacts with an amine function; then addition of a polyamide oligomer on it pre-grafted copolymer. 4. Process according to claim 3, characterized in that the monomer which reacts with an amine function is selected from citracon, fumar, mesacon, 3-allyl succinic and preferably maleic anhydride. 5. Alloy of at least two incompatible thermoplastic polymers made compatible by the addition of compounds according to claims 1 or 2. 6. Alloy according to claim 5, characterized in that it contains the graft copolymer according to any one of claims 1 or 2 and one of the following thermoplastic polymer pairs: aliphatic (co)polyamide- (co)polymer of propylene and/or ethylene, semi- aromatic (co)polyamide-(co)polymer of propylene and/or ethylene, blockamide polyether/- (co)polymer of propylene and/or ethylene, vinylphenol polymer (co)polymer of propylene and/or ethylene, hydrolyzed ethylene vinyl acetate (co )polymer of propylene and/or ethylene. 7. Alloy according to claim 6, characterized in that it is selected from the following pairs: Polyamide-6 - polypropylene Polyamide-6 - polyethylene Polyamide-6 - ethylene/propylene copolymer Polyamide-11 or 12 - polypropylene or polyethylene or ethylene/propylene copolymer Hydrolyzed ethylene - vinyl acetate copolymer - polypropylene or polyethylene or ethylene/propylene copolymer Polyparavinylphenol - polypropylene or polyethylene or ethylene/propylene copolymer Polyether block-amide -polypropylene or polyethylene or ethylene/propylene copolymer Semi-aromatic polyamide - polypropylene or polyethylene or ethylene/propylene copolymer. 8. Alloy according to any one of claims 5 to 7, characterized in that it contains 0.1 to 30% by weight of graft copolymer as stated in claims 1 or 2 and preferably 5 to 15%, calculated on the weight of the thermoplastic resin mixture.