DE2435266A1 - FILLED THERMOPLASTIC POLYAMIDE MOLDING COMPOUNDS WITH IMPROVED TOUGHNESS - Google Patents

Description

Our sign; OZ 30 674 Ka / Wn 67OO Ludwigshafen, February 2, 1974

Filled thermoplastic polyamide molding compounds with improved toughness

The invention relates to filled thermoplastic polyamide molding compounds with increased dry and kaite impact strength and improved Fracture toughness under multiaxial stress. In contrast to unreinforced polyamide molding compounds, filled or, fiber-reinforced polyamides have significantly higher tensile and bending strengths with 3 to 4 times higher Ε-module, while the toughness properties are less favorable compared to unfilled polyamides »They are therefore reinforced polyamide molding compounds with increased toughness is desirable without significantly impairing strength and stiffness.

In the case of unfilled polyamide molding compounds, some processes for increasing the toughness are already known for example, incorporate low molecular weight plasticizers into the polyamide. However, this procedure is because of the risk of Unsatisfactory bubble formation in the molding. In addition, most of the plasticizers suitable for plastics are Not sufficiently compatible with polyamides and therefore separate during processing or tend to exude. Compatible Plasticizers, on the other hand, which form real solutions with polyamides, usually set the high mechanical level of these Plastics.

If you equip such plasticized polyamides with fillers or glass fibers, the desired one is usually Rigidity not achieved or only achieved with very large amounts of reinforcing fillers. In most cases it will also by plasticizing additives the adhesion between the surface of the material and plastic matrix so deteriorated that the

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Tensile and flexural strengths measured on test specimens too low will.

The present invention was based on the object of developing filled or reinforced molding compositions based on polyamides, which have a high impact or fracture toughness, at the same time still have high tensile strength and rigidity and with thermal stability, good aging resistance and color constancy during processing, in addition, good adhesion Show reinforcing or fillers. It has been shown that this object by the molding compositions according to the present Invention can be solved. The filled thermoplastic molding compositions of the invention of high toughness are characterized by that they

A) a polyamide with a relative viscosity of 2.30 to 3.60, measured 1% in concentrated sulfuric acid, and

B) a rubber-elastic graft copolymer (except of monomers having conjugated double bonds) which has a glass transition temperature below -20 ⁰ C, wherein the components A and B in a weight ratio of 99 * 5 ϊ 0.5 to 80: stand 20, as well as

C) optionally 0.01 to 3 percent by weight, based on Polyamide, crosslinker and

D) optionally reinforcing fillers in amounts of 5 to 100 percent by weight, based on the polymer matrix,

contain.

The fact that special graft polymers, optionally in combination with the crosslinkers that act synergistically on the mechanical properties, compared to those previously proposed Giving products to the filled polyamide molding compositions outstanding advantageous properties was for the Surprising to the person skilled in the art and in no way foreseeable. So far there has been no lack of efforts, for example impact modified polystyrene or impact modified

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To equip SAN (ABS) with fibrous fillers in such a way that high rigidity of the molding compounds is also obtained while maintaining the high toughness. As experience shows, can indeed achieve relatively good stiffness in this way, however, good impact resistance and favorable fracture behavior go nearly ^s completely lost.

Polyamides which can be used as component A for the purposes of the invention are, for example, linear polycondensates of lactams with 6 to 12 carbon atoms or conventional polycondensates of diamines and dicarboxylic acids, such as 6,6-, 6,8-, 6,9- . " 6.10, 6.12, 8.8, 12.12 polyamide. There are also polycondensates of aromatic dicarboxylic acids, such as isophthalic acid, terephthalic acid with diamines, such as hexamethylenediamine or octamethylenediamine, polycondensates of araliphatic starting materials, such as m- and p-xyIylenediamines and adipic acid, suberic acid and sebacic acid, as well as polycondensate based on alicyclic acid, such as cyclohexarboxylic acid and sebacic acid, such as cyclohexanediamine starting materials , 4,4'-diaminodicyclohexylmethane and 4,4 ^f -Diaminodicyclohexylpropan, into consideration.

An essential feature of the novel molding compositions is their content of component B, ie rubbery graft copolymers which have a glass transition temperature below -20 ⁰ C. Graft copolymers should be understood to mean products which are obtainable by polymerizing monomers in the presence of prepolymers, a substantial part of the monomer being grafted onto prepolymer molecules. DA * e Herssibe.Llin g of such graft copolymers is known in principle, compare in particular RJ Ceresa, Block and Graft Copolymers (Butterworth, London, 1962).

Are in principle suitable for the present process all of the usual graft copolymer having rubber-elastic properties, unless they are made from dienes having conjugated double bonds and provided that their glass transition temperature below -20 ⁰ C, in particular between -I50 and -2O ⁰ C, preferably between -80 and -30 ⁰ C. The determination of the glass transition temperature can, for example, according to the

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B. Vollmer, Plan of Macromolecular Chemistry, pages 4θβ to 410, Springer Verlag, Heidelberg, 1962, specified methods. Graft copolymers made from monomers, which contain conjugated double bonds are unsuitable because they are polyamide molding compounds with insufficient stability against exposure to light, heat and oxygen.

For the production of rubber-elastic graft copolymers, a prepolymer 1 is used as the starting point, for example

a) 10 to 99 percent by weight of an acrylic ester of a C - to C _lt - alcohol,

b) 1 to 90 percent by weight of a two olefinic double bond, which are not conjugated, bearing monomers and

c) if appropriate, up to 25 percent by weight of further monomers has been produced.

This prepolymer 1 is then grafted with the components 2, 3 and 4 described below, i.e. it is polymerized 2, 3 and 4 in the presence of a prepolymer 1. Advantageous graft copolymers are obtained, for example, using from prepolymers 1

a) 10 to 99 percent by weight, preferably 30 to 98 percent by weight, in particular 50 to 99 percent by weight of an acrylic ester of an alcohol with 1 to 10 carbon atoms, preferably 4 to 8 carbon atoms, such as acrylic acid n-butyl ester, -octyl ester or -äthylhexylester,

b) 1 to 90 percent by weight, preferably 2 to 70 percent by weight, in particular 2 to 50 percent by weight of two olefinic double bonds which are not conjugated should, carrying monomers such as vinylcyclohexane, cyclooctadiene-1,5 and / or esters derived from unsaturated alcohols, such as vinyl acrylate, alkyl acrylate, tricyclodocenyl acrylate and / or diallyl phthalate and / or

c) optionally up to 25 percent by weight of other usual ones

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Monomers, such as vinyl ethers, vinyl esters, vinyl halides, vinyl substituted heterocyclic compounds such as vinyl pyrrolidone (whereby the percentages mentioned under a to c add up to 100).

Component b is essential for the subsequent grafting. The double bonds built into the prepolymer by b serve - depending on the reactivity, to varying degrees as grafting points at which the polymer molecule is subsequently added continues to grow.

Such prepolymers 1 are now grafted (per 100 parts of prepolymer)

2) 10 to 85 parts by weight, in particular 20 to 70 parts by weight, of styrene and / or methacrylic acid ester and / or (meth) acrylic acid as

3) optionally up to 35 parts by weight, expediently 10 to 50 % of the styrene, of acrylonitrile or methacrylonitrile as well

4) optionally up to 20 parts by weight of other monomers, such as acrylic esters, vinyl esters, vinyl ethers or vinyl halides, vinyl substituted heterocyclic compounds such as vinyl pyrrolidone.

It is advantageous if the graft copolymers have a considerable Have polar group content. It is therefore expedient to choose products that contain more than 10 percent by weight (Meth) acrylic acid esters and (meth) acrylonitrile are built up. If the content of (meth) acrylic esters is more than 70 percent by weight, it is expedient to dispense with (meth) acrylonitrile as a building block.

The prepolymers and the graft copolymers are prepared in a customary manner, preferably by emulsion polymerization with customary free radical initiators, emulsifiers and regulators in aqueous emulsion or dispersion. The production A suitable graft copolymer is described, for example, in German patents 1 2βθ 135 and 1,238,207.

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The new molding compositions contain components A and B in a weight ratio 99.5: 0.5 to 80:20, advantageously between 94: 6 and 85:15, in particular between 90:10.

Crosslinkers in the sense of the invention as component C are monoisocyanates, Monoisothiocyanates, diisocyanates, diisothiocyanates, polyisocyanates, polyisothiocyanates and / or carbodiimides and / or methylenebiscaprolactam and / or trimesic acid / hexamethylenediamine salt, Benzene-1,2,4-tricarboxylic acid / hexamethyldiarain salt, Cyanuric acid / hexamethyldiamine salt and / or styrene / maleic anhydride copolymers or oc-methylstyrene / maleic anhydride copolymers.

In principle, all known isocyanates are used for the production of the impact-resistant, filled polyamide molding compositions according to the invention (in the sense explained above) suitable. Isocyanates or isothiocyanates are particularly used with at least 2 NCO or 2 NCS groups in the molecule of the general formula

(SCN) OCN - R - NCO (NCS)

in which R is an aliphatic, aliphatic and / or aromatic Radical or a substituted derivative thereof, with the proviso that the substituent is not with an isocyanate group or isothiocyanate group reacts. Suitable substituents are groups such as the sulfoxy, sulfonyl, alkoxy, aryloxy, Oxo and ester group. Each diisocyanate is characterized by a specific hydrocarbon residue.

As examples of diisocyanates with aliphatic hydrocarbon radicals be tetramethylene diisocyanate, hexamethylene diisocyanate, Dodecamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate called. Examples of diisocyanates with an alicyclic hydrocarbon radical are cyclohexane diisocyanate (l, 3) or - (1,4), isophorone diisocyanate, bis (3-methyl-4-isocy.anatocyclohexyl) methane, Bis (4-isocyanatocyclohexyl) methane and 2,2-bis (4-isocyanatocyclohexyl) propane. Examples for diisocyanates with an aromatic hydrocarbon radical are m- and p-phenylene diisocyanates, bipheny! diisocyanates and

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Naphthylene diisocyanates. Examples of diisocyanates with hydrocarbon radicals of more than one type are tolylene-2,4 and 2,6-diisocyanate, durene diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl 1-4,4'-biphenylene diisocyanate, 4, 4'-diphenylisopropylidene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 4- (4-isocyanatocyelohexyl) phenyl isocyanate and 4-isocyanatobenzyl isocyanate and the like. In the above examples, the isocyanate groups are partly bound to the same and partly to different organic radicals. Diisocyanates with functionally substituted organic radicals can also be used, for example 4,4'-diphenylsulfone diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, di- (j5-isocyanatopropyl) ether and Ester isocyanates, such as lysine ester diisocyanates, triisocyanatoarylphosphorus (thio) esters or glycol di-p-isocyanatophenyl esters. Further specific diisocyanates which can be used to carry out the invention are known from the literature, see, for example, "Mono- and polyisocyanates", W. Siefken, Annalen der Chemie, 562 , 6-136 (1949). Partially polymerized isocyanates with isocyanurate rings and free NCO groups, and also polyisocyanates containing urethane, allophanate, amide and urea groups, or compounds which split off isocyanate are also suitable. Instead of the isocyanates listed, the corresponding isothiocyanates can be used analogously.

For the production of the impact-resistant polyamide molding compounds according to the invention blocked isocyanates or compounds which split off isocyanates are particularly suitable.

Blocked isocyanates are, for example, dimeric isocyanates, Isocyanate-releasing compounds are, for example, adducts of isocyanates with OH-, NH-, C-H-, SH-acidic compounds, such as Adducts of toluene (2,4) diisocyanate with phenol or o-chlorophenol, with cyclic lactams, such as pyrrolidone, Caprolactam, Capryllactam or Laurinlactam as well as with malonic acid diethyl ester.

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Possible reinforcing fillers D are those which increase the rigidity of the polyamides. Preferred are fibrous materials, in particular glass fibers made of low-alkali Ε-glass with a fiber diameter between 0 8 and ] A / u and a glass fiber length in the injection molded part between 0.01 and 0.5 mm. The glass fibers can be as continuous fibers or be used as cut or ground glass fibers, the fibers with a suitable sizing system and a Adhesion promoter or adhesion promoter system based on silane could be.

However, other fibrous reinforcement materials such as carbon fibers, K-TJttanat single crystal fibers, gypsum fibers, aluminum oxide fibers or asbestos can also be incorporated. Ni _M chtfasrige fillers such as glass spheres, hollow glass spheres or chalk, quartz, natural or calcined kaolins are also preferred as combinations of these materials with glass fibers. Like the glass fibers, these fillers can also be provided with a size and / or an adhesion promoter or adhesion promoter system.

The filled thermoplastic polyamide molding compositions according to the invention can be produced by the processes customary for melt processing, as described, for example, in the Kunststoffhandbuch, Volume VI, Polyamide, Munich 1966, and in the American patent 3 J> OK 282.

The filled polyamide molding compositions according to the invention can also contain flame-retardant additives based on elemental substances red phosphorus, phosphorus compounds, halogen and nitrogen compounds, antimony oxides, iron oxides, zinc oxide, furthermore nor dyes and color pigments, stabilizers against thermal, thermo-oxidative and UV damage, waxes, lubricants and Processing aids that ensure trouble-free extrusion and injection molding, as well as contain antistatic agents.

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Composition; of the graft polymer I; Prepolymer graft component

98 wt.% Of acrylic acid-n-butyl ester 75 wt.% Styrene 2 wt.% Tricyclodecenyl% of acrylonitrile 25 wt.

60: 40 parts

Composition of the graft polymer II; Prepolymer graft component

98 wt. $ Acrylic acid-n-butyl ester 75 wt.% Styrene 2 wt.% Diallyl phthalate% of acrylonitrile 25 wt.

60: 40 parts

example 1

9,200 g of a polyamide 6 with a K value of 72 (measured by the method of H. Fikentscher, Cellulosechemie I3 (1932), page 58, in a 1% solution in concentrated sulfuric acid) and 8OO g of a graft rubber I were in a fluid mixer at room temperature intimately mixed. The mixture was then melted in a twin-screw extruder heated to 280 ° C. and 5 ^ 84 g of Ε glass fibers, which had been equipped with a size and an aminoxilane, were added to the melt. The extruded mixture was granulated, dried and processed into test specimens on an injection molding machine at injection temperatures of 290 and 310 ° C. The injection molded parts were tested dry in the spray-frishe state. The impact strength in [cmkp / cm 3 according to DIN 53 453, the tensile strength in [kpcm " ² ^ according to DIN 53 455, the Ε-module in [kpcnf ² ] according to DIN 53 457 and the fracture energy in [cmkpj at 2 χ 60 mm round washers tested according to DIN draft 53 443.

Example 2

The procedure was as in Example 1, but graft rubber II used.

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Example 3

9200 g of a polyamide β (with a K value of 72), 8θΟ g of a graft rubber I and 45 g of 4,4'-Diphenylrnethandiisocyanat were in intimately mixed in a fluid mixer at room temperature. The incorporation of 5384 g of glass fibers and the testing of the mechanical Properties were as set out in Example 1.

Example 4

9200 g of a polyamide β (with a K value of 72), 800 g of a graft rubber I and 200 g of a static copolymer of 70 parts by weight of styrene and 30 parts by weight of maleic anhydride were intimately mixed in a fluid mixer at room temperature. The incorporation of 5492 g of glass fibers and the The mechanical properties were tested as described in Example 1.

Example 5 (comparative example)

9200 g of a polyamide with a K value of 72 were melted at 280 ° C in a twin-screw extruder and 4954 g of glass fibers, which were equipped with a size and an aminosilane, added to the melt. Furthermore, as in Example 1 explained procedure.

Those on the injection molded parts according to the examples and the comparative example The measured values obtained are compiled in the table below.

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Type of exam
Injection temperature Impact strength
280 ° C 300 ⁰ C. 55.3 Lcmkp / cra J
310 ⁰ C Fracture energy
28O ⁰ C 300 ⁰ C 60.3 Lcmkp]
310 ⁰ C tensile strenght
[, kpcm '^ J Modulus of elasticity
QcpcrrT ² ] example 1 53.7 56.4 55.7 44.1 63.6 67.2 1773 111000 Example 2 53.9 56.8
61.2 56.8 50.6 66.3
62.6 67.4 1708 112000 cn
o Example 3
CD
^ Example 4
öö 54.3
57.4 52.4 60.2
61.4 50.6
45.8 24.2 69.0
70.9 I813
I69O IO9OOO
IO5OOO ^ Example 5
_ö (comparison)
ω
K) 51.4 50.2 32.2 17.6 I863 112000

Claims (12)

Claims 1. Filled, thermoplastic polyamide molding compositions with high toughness, characterized in that they contain A) a polyamide with a relative viscosity of 2.30 to 3.60, measured 1 % ± g in concentrated sulfuric acid, and B) a rubber-elastic graft copolymer (with the exception of those made from monomers with conjugated double bonds) which has a glass transition temperature below -20 ⁰ C, the weight ratio of component A to component B being 99.5: 0.5 to 80 ι 20, and additionally D) optionally 0.01 to 3 percent by weight, based on Polyamide, crosslinker and C) 5 to 100 percent by weight, based on the polymer matrix, reinforcing fillers. 2. Filled, thermoplastic polyamide molding compositions according to claim 1, characterized in that they contain as component B a graft copolymer which is obtained by being in the presence of 1) 100 parts by weight of a prepolymer a) 10 to 99 percent by weight of an acrylic ester of a C ₁ - to C ₁₅ -AlkOhOIs, b) 1 to 90 percent by weight of two olefinic double bonds that should not be conjugated, bearing monomers and / or Aor§ri3ä ^ fe% ern, which derive from unsaturated alcohols, and / or c) optionally up to 25 percent by weight of others common monomer, 2) 10 to 85 parts by weight of methacrylic acid ester and / or (Meth ~) acrylic acid and / or styrene, 3) optionally up to 35 parts by weight of acrylonitrile and / or methacrylonitrile and 4) optionally up to 20 parts by weight of further monomers polymerized, ^ 09887/0862 -i> - 13 - ο.ζ. 30th 2A35266 3. Filled, thermoplastic polyamide molding compositions according to claim 1 and 2, characterized in that the acrylic ester 1 is a n-butyl acrylic ester and / or octyl acrylic ester and / or ethylhexyl acrylic ester. 4. Filled, thermoplastic polyamide molding compositions according to claim 1 and 2, characterized in that the olefin 1b is vinylcyclohexane and / or cyclooctadiene-1,5, 5. Filled, thermoplastic polyamide molding compositions with high toughness according to Claim 1 and 2, characterized in that the ester 1b is vinyl acrylate and / or alkyl acrylate and / or tricyclodecenyl acrylate and / or diallyl phthalate. 6. Filled, thermoplastic polyamide molding compositions with high toughness according to Claim 1 and 2, characterized in that component C 4,4'-diphenylmethane diisocyanate and / or the dimer of toluene-2,4-diisocyanate and / or the adduct of hexamethylene diisocyanate with t -Caprolactam and / or polycarbodiimide with a molecular weight above 500 and a content of more than three carbodiimides. 7. Filled, thermoplastic polyamide molding compositions with high toughness according to Claim 1 and 2, characterized in that component C is methylenebiscaprolactam and / or benzene tricarboxylic acid (1,3,5) -hexamethylene diamine salt and / or benzenetricarboxylic acid (1,2,4) -Hexamethylene diamine salt and / or cyanuric acid / hexamethylene diamine salt and / or a carboxylic acid anhydride and / or a styrene / maleic anhydride copolymer. 8. Filled, thermoplastic polyamide molding compositions with high toughness according to claim 1 and 2, characterized in that component D consists of glass fibers with an average diameter of 8 to 14 / µm and a length between 0.01 and 0.5 mm. -14-509887 / 0862 - i4 - ο.ζ. 30th 9. Filled, thermoplastic polyamide molding compositions with high toughness according to claim 1 and 2, characterized in that component D consists of glass spheres with a diameter of 10 to 500 / U. 10. Filled, thermoplastic polyamide molding compositions with high toughness according to claim 1 and 2, characterized in that component D consists of a fibrous filler based on carbon, potassium titanate, gypsum, aluminum oxide or asbestos. 11. Filled, thermoplastic polyamide molding compositions with high toughness according to claim 1 and 2, characterized in that component D consists of mineral fillers such as chalk, quartz powder and kaolin. 12. Filled, thermoplastic polyamide molding compositions with high toughness according to claim 1 and 2, characterized in that they contain 3 to 15 percent by weight, based on the amount of polyamide, of an organic halogen, phosphorus or nitrogen compound stable under the conditions of melt processing, alone or in Combination with 2 to 10 percent by weight, based on the amount of polyamide, of a synergistically active metal compound, preferably antimony trioxide, and / or 2 to 12 percent by weight, based on the amount of polyamide, contain elemental red phosphorus. BASF Aktiengesellschaft I 509887/0862