Halogen-free sulphonic acid ester and/or sulphinic acid ester as flame retardant, flame retardant synergists and radical generators in plastics

Abstract

The present invention relates to the use of halogen-free sulphonic acid esters and/or sulphinic acid esters as flame retardant and/or flame retardant synergists in plastics. The invention furthermore relates to the use of said compounds as radical generators in plastics, particularly in order to increase the molecular weight of the plastics, to branch and/or cross-link the plastics, to reduce the molecular weight of the plastics, to influence the molecular weight distribution of the plastics and to graft unsaturated monomers to the plastics. The present invention furthermore relates to the use of flame-retardant plastic compositions in the electrical or electronics industry, construction industry, transport industry, preferably automobiles, aircraft, trains and ships, for medical applications, for household appliances, vehicle parts, consumer products, packaging, furniture and textiles.

Claims

1. A method of imparting flame retardancy to a plastic such that the resulting flame retarded plastic has a flame retardancy rating of V-2 or better according to UL-94, the method comprising incorporating into the plastic at least one halogen-free sulfonic ester and/or at least one halogen-free sulfinic ester as a flame retardant and/or a flame retardant synergist, wherein the at least one halogen-free sulfonic ester or the at least one halogen-free sulfinic ester is a halogen-free sulfonic acid azanyl ester of the general formula (Ia) and/or halogen-free sulfinic acid azanyl ester of the general formula (Ib); ##STR00043## wherein radicals R.sup.1 and R.sup.2 are independently selected from the group consisting of substituted or unsubstituted alkyl groups, heteroalkyl groups, cycloalkyl groups, heterocycloalkyl groups, acyl groups, aryl groups and heteroaryl groups, where two radicals R.sup.2 can form a cyclic system; wherein the plastic is a polymer of olefin or diolefin; and wherein the at least one halogen-free sulfonic ester and/or halogen-free sulfinic ester is incorporated further in combination with a further flame retardant compound which is a phosphorus-containing flame retardant; wherein, in the resulting flame retarded plastic, the plastic is present in an amount of 60 to 90 wt. %, the halogen-free sulfonic ester and/or halogen-free sulfinic ester is present in an amount of 2 to 5 wt. %, and the further flame retardant is present in an amount of 5 to 15 wt. %.

2. The method of claim 1, wherein the halogen-free sulfonic ester is a sulfonic acid azanyl ester selected from the group consisting of compounds having the following formulae, or mixtures thereof: ##STR00044## where R.sup.2 has the same definition as indicated above; and R.sup.3 is selected from the group consisting of substituted or unsubstituted alkyl groups, heteroalkyl groups, cycloalkyl groups, and heterocycloalkyl groups; where R.sup.2 and R.sup.3 can form a cyclic system; and where the aromatic structural units can be substituted; where alkyl groups are as substituents.

3. The method of claim 2, wherein the halogen-free sulfonic ester is a sulfonic acid azanyl ester having the formula indicated below: ##STR00045## where R.sup.3 is selected from the group consisting of substituted or unsubstituted alkyl groups, heteroalkyl groups, cycloalkyl groups, heterocycloalkyl groups and a cyclic system formed from two radicals R.sup.3.

4. The method of claim 1, wherein the halogen-free sulfonic ester is a sulfonic acid azanyl ester in oligomeric or polymeric form, prepared by polymerization or polymer-analogous reaction from monomers selected from the group consisting of one of the compounds having the formulae below, or mixtures thereof: ##STR00046##

5. The method of claim 1, wherein the at least one halogen-free sulfonic ester and/or halogen-free sulfinic ester and the further flame retardant compound are incorporated further in combination with an additional compound selected from (v) radical initiators; (vi) borates; (vii) sulfur-containing compounds; (viii) anti-drip agents; (ix) silicon-containing compounds; (x) salts of sulfonic acids; (xi) smoke suppressants; (xii) carbon compounds; and (xiii) mixtures, combinations or blends of two or more of the additional compounds stated under (v) to (xii).

6. A flame-retarded plastic composition comprising components (A) to (D), wherein: (A) 60 to 90 wt % of a polymer of olefin or diolefin; (B) 2 to 5 wt % of at least one flame retardant comprising at least one halogen-free sulfonic ester and/or at least one halogen-free sulfinic ester, and mixtures thereof; wherein the at least one halogen-free sulfonic ester or the at least one halogen-free sulfinic ester is a halogen-free sulfonic acid azanyl ester of the general formula (Ia) and/or halogen-free sulfinic acid azanyl ester of the general formula (Ib); ##STR00047## wherein radicals R.sup.1 and R.sup.2 are independently selected from the group consisting of substituted or unsubstituted alkyl groups, heteroalkyl groups, cycloalkyl groups, heterocycloalkyl groups, acyl groups, aryl groups and heteroaryl groups, where two radicals R.sup.2 can form a cyclic system; (C) 5 to 15 wt % of at least one non-(B) flame retardant or flame retardant synergist, and mixtures thereof; wherein the at least one non-(B) flame retardant or flame retardant synergist is a phosphorus-containing flame retardant; and (D) 0 to 50 wt % of at least one additive or adjuvant; wherein the weight fractions of components (A) to (D) add up to 100 wt %; and wherein the flame retarded plastic composition has a flame retardancy rating of V-2 or better according to UL-94.

7. The flame-retarded plastic composition of claim 6, which further includes a compound selected from the group consisting of (v) radical initiators; (vi) halogen-containing flame retardants based on chlorine and bromine,; (vii) borates; (viii) sulfur-containing compounds; (ix) anti-drip agents; (x) silicon-containing compounds; (xi) salts of sulfonic acids; (xii) smoke suppressants; (xiii) carbon compounds; and (xiv) mixtures, combinations or blends of two or more of the substances stated under (v) to (xiii).

8. The flame-retarded plastic composition of claim 6, which is free from antimony compounds.

9. The flame-retarded plastic composition of claim 6, wherein component (D) is selected from the group consisting of UV absorbers, light stabilizers, UV stabilizers, and mixtures thereof; acid scavengers are selected from the group consisting of salts of long-chain carboxylic acids, calcium stearate, magnesium stearate, zinc stearate, calcium lactate, calcium stearoyl-2-lactylate, and hydrotalcites; light stabilizers and UV stabilizers are selected from the group consisting of phenolic antioxidants, phosphites, phosphonites, sterically hindered amines (HALS), and mixtures thereof; phenolic antioxidants are selected from the group consisting of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(3,5-di-tert-butyl-4-hydroxyphenyl) isocyanurate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenyl) isocyanurate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, triethylene glycol bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, N,N′-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide, and mixtures thereof; phosphites and phosphonites are selected from the group consisting of tris(2,4-di-tert-butylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,4-dicumylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, diisodecyloxypentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite, bis(2,4,6-tris(tert-butylphenyl) pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4′- biphenylenediphosphonite, and mixtures thereof; aminic antioxidants are selected from the group consisting of N,N′-diisopropyl-p-phenylenediamine, N,N′-di-sec-butyl-p-phenylenediamine, N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine, N,N′-bis(1-ethyl-3- methylpentyl)-p-phenylenediamine, N,N′-bis(1-methylheptyl)-p-phenylenediamine, N,N′-dicyclohexyl-p-phenylenediamine, N,N′-diphenyl -p-phenylenediamine, N,N′-bis(2-naphthyl)-p-phenylenediamine, N-isopropyl-N′-phenyl-p -phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, N-(1-methylheptyl)-N′-phenyl-p-phenylenediamine, N-cyclohexyl-N′-phenyl-p-phenylenediamine, and mixtures thereof; sulfur-containing antioxidants are selected from the group consisting of distearyl thiodipropionate, dilauryl dipropionate, and mixtures thereof; hydroxylamines are selected from the group consisting of N,N-dialkylhydroxylamine, N,N-dibenzylhydroxylamine, N,N-dilaurylhydroxylamine, N,N-distearylhydroxylamine, N-benzyl a-phenyl nitrone, N-octadecyl α-hexadecyl nitrone; and/or sterically hindered amines are selected from the group consisting of 1,1-bis(2,2,6,6-tetramethyl-4-piperidyl) succinate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensation product of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, linear or cyclic condensation products of N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylendiamine and 4-tert-octylamino-2,6-di-chloro-1,3,5-triazine, tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate, tetrakis(2,2,6,6-tetra-methyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, 1,1′-(1,2-ethanediyl)bis(3,3,5,5-tetramethylpiperazinone), 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, linear or cyclic condensation products of N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylendiamine and 4-morpholino-2,6-dichloro-1,3,5-triazine, the reaction product of 7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro[4.5]decane and epichlorohydrin, and mixtures thereof.

10. The flame-retarded plastic composition of claim 6, wherein component (A) is present at 60 to 90 wt % based on the total weight of the flame-retarded plastic composition; component (B) is present at 2 to 5 wt % based on the total weight of the flame-retarded plastic composition; component (C) is present at 5 to 15 wt % based on the total weight of the flame-retarded plastic composition; and component (D) is present at 0.05 to 30 wt % based on the total weight of the flame-retarded plastic composition.

11. The flame-retarded plastic composition of claim 6, wherein the flame retarded plastic is a flame retarded polymer of olefin or diolefin utilized in electrical or electronics industry, mechanical engineering, apparatus construction, building industry, transport industry, medical application, household appliance, vehicle part, cable, consumer good, packaging, furniture, or textile.

12. The method of claim 1, wherein the halogen-free sulfonic acid azanyl ester and/or halogen-free sulfinic acid azanyl ester act as radical generators when modifying plastic.

13. The method of claim 1, wherein the halogen-free sulfonic ester is a sulfonic acid azanyl ester and is selected from the group consisting of the compounds having the following formulae and mixtures thereof: ##STR00048## ##STR00049## ##STR00050##

Description

EXPERIMENTAL SECTION

Preparation of the Inventive Flame Retardants

Compound A: 1H-Isoindole-1,3(2H)-dione, 2-[[(4-methylphenyl)sulfonyl]oxy]

(1) ##STR00040##

(2) A baked triple-neck flask is charged with 16.028 g of N-hydroxyphthalimide (98.25 mmol), 20.576 g of para-toluenesulfonyl chloride (107.9 mmol) and 320 mL of dichloromethane. Under a nitrogen atmosphere, 16 mL of pyridine are added. The suspension is stirred at room temperature for 1 h. After the reaction, the solution is extracted by shaking three times with water (150 mL) and the solvent is subsequently removed on a rotary evaporator. In this procedure, a yellow solid is precipitated. The product is washed with water in a filter. The product yield is 29.7679 g (98.1 mmol, 99.8%). .sup.1H NMR (CDCl.sub.3, 300 MHz) δ 2.43 (s, 3H), 7.32-7.35 (m, 2H), 7.71-7.81 (m, 4H), 7.87-7.90 (m, 2H).

Compound B: Benzo[1,2-c:4,5-c′]dipyrrole-1,3,5,7(2H,6H)-tetrone, 2,6-bis[[(4-methylphenyl)sulfonyl]oxy]

(3) ##STR00041##

(4) In a baked Schlenk flask, under a nitrogen atmosphere, 5.9096 g of para-toluenesulfonic acid (31.0 mmol) and 3.4453 g of N-dihydroxypyromellitimide (13.9 mmol) are dissolved in dichloromethane (120 mL). The reaction solution is admixed with 11 mL of pyridine. The addition of pyridine is followed by the precipitation of a yellow solid. The suspension is stirred at room temperature for 16 h. The crude product is subsequently washed with dichloromethane and water. The product yield is 5.9507 g (10.7 mmol, 77.0%). .sup.1H NMR (DMSO, 300 MHz) δ 2.47 (s, 6H), 7.52-7.55 (m, 4H), 7.96-7.99 (m, 4H), 8.39 (s, 2H).

Compound C: 4,8-Ethenobenzo[1,2-c:4,5-c′]dipyrrole-1,3,5,7(2H,6H)-tetrone, 3a,4,4a,7a,8,8a-hexahydro-2,6-bis[[(4-methylphenyl)sulfonyl]oxy]

(5) ##STR00042##

(6) The synthesis is carried out in a baked Schlenk flask under a nitrogen atmosphere. 15.4331 g of para-toluenesulfonic acid (80.9 mmol) and 9.0077 g of bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxyldiimide (32.4 mmol) are dissolved in dichloromethane (350 mL). The reaction solution is admixed with 15 mL of pyridine. The solution is stirred at room temperature for 17 h, during which a white solid is precipitated. The crude product precipitated is filtered and washed with water. The product yield is 17.860 g (30.44 mmol, 94.0%). .sup.1H NMR (DMSO, 300 MHz) δ 2.47 (s, 6H), 6.22 (s, 2H), 7.53-7.56 (m, 4H), 7.85-7.88 (m, 4H).
Production and Testing of Flame-Retarded Inventive Plastics Compositions

(7) The polypropylene samples (Braskem Inspire 153) are extruded at a temperature of 200° C. and a screw speed of 200 rpm on an 11 mm twin-screw extruder (Process 11 from Thermo Scientific). The desired ratio of polymer to flame retardant is initially homogenized by mixing and supplied to the extrusion via a volumetric feed. After the extrusion, the polymer extrudate is pelletized.

(8) Specimens for fire testing are pressed from the resultant pellets at 200° C. for a total of 3 minutes, applying a pressure of one tonne for 1 minute and a pressure of 2 tonnes for 2 minutes. The specimens as per standard have the following dimensions: 125×13×1.6 mm.

(9) The inventive examples and comparative examples contained in the table were tested according to DIN EN 60695-11-10, giving the following burn times and classification as per standard:

(10) TABLE-US-00001 Burn times Total of afterburn times of 5 test Classification specimens for 2 according to Flame retardant exposures to flame DIN EN Examples composition.sup.a [in seconds] 60695-11-10 CB1 no flame >100 n.c. retardant CB2 10% phosphazene >100 n.c. IB1 2% A 0 V-2 5% phosphonate IB2 2% A 0 V-0 8% phosphonate IB3 2% A 0 V-0 15% phosphonate IB4 2% B 4.3 V-2 8% phosphonate IB5 2% B 1.9 V-2 15% phosphonate IB6 5% B 0 V-2 10% phosphonate IB7 2% C 0.9 V-2 5% phosphonate IB8 2% C 1.3 V-2 8% phosphonate IB9 2% C 0 V-2 15% phosphonate IB10 5% C 28.2 V-2 10% phosphazene .sup.aFigures in wt % based on the total amount of flame retardant(s) and polymer; n.c. = not classified.

(11) The phosphonate is a commercial product available under the name Aflammit PCO 900 from Thor. The phosphazene is a commercial product available under the name SPB-100 from Otsuka Chemicals.

(12) The inventive examples are self-extinguishing after removal of the ignition source and have very short burn times, receiving a V-0 or V-2 classification.

(13) The following compositions were processed, and examined for their flame behavior, in the same way as for examples IB1 to IB10. As a difference, the test specimens were produced by injection molding at a maximum temperature of 210° C.

(14) TABLE-US-00002 Burn times Total of afterburn times of 5 test Classification specimens for 2 according to Flame retardant exposures to flame DIN EN Examples composition.sup.a [in seconds] 60695-11-10 CB3 15% PSPPP  100 n.c. CB4 8% Phoslite B 85  100 n.c. CB5 15% PX-202  100 n.c. IB11 2% A 7.5 V-2 8% PSPPP IB12 2% A 0 V-0 8% Phoslite B 85 IB13 1.5% A 0 V-0 4% PCO 910 IB14 2% A 0 V-0 15% PX-202 .sup.aFigures in wt % based on the total amount of flame retardant(s) and polymer; PSPPP = Polysulfonyl diphenylene phenylphosphonate Phoslite B 85 = Aluminum hypophosphite as main component (manufacturer: Italmatch) PCO 910 = Aflammit PCO 910, phosphonate, commercial product from Thor. PX-202 = Phosphate ester, commercial product from Daihachi, Osaka, JP. C) The following compositions were processed in polyethylene (LDPE, LD 185, Exxon Mobil) at a maximum temperature of 190° C. at a speed of 150 rpm, and investigated for their flame behavior, in analogy to examples IB11 to 1B14. The test specimens were produced by injection molding at a maximum temperature of 190° C.

(15) TABLE-US-00003 Burn times Total of afterburn times of 5 test Classification specimens for 2 according to Flame retardant exposures to flame DIN EN Examples composition.sup.a [in seconds] 60695-11-10 C1 2% A 0 V-0 5% PCO 910 C2 2% A 0 V-0 8% PCO 910 D) Instead of test specimens, films of polypropylene were produced by compression molding from the extruded pellets, at temperatures reported in the table, in analogy to examples IB1 to IB10. The resulting films were tested according to the DIN 4102 B2 standard, and additionally the fire time and fire height were determined.

(16) TABLE-US-00004 Flame Processing Film Burn retardant temper- thick- DIN times Fire Exam- compo- ature ness 4102 [in height ples sition.sup.a [° C.] [mm] B2 seconds] [mm] CD1 No addition 190 0.20 Fail Complete Complete com- com- bustion bustion ID1 0.5% A 190 0.23 Pass 43 ID2 0.5% A 220 0.18 Pass 0 43 ID3 0.5% A 250 0.27 Pass 0 52 ID4 1.0 A 220 0.27 Pass 0 45

(17) The polymer films comprising the inventive compounds meet the B 4102 B2 standard, in contrast to the comparative example. E) Instead of test specimens, films of LD-polyethylene were produced by compression molding from the extruded pellets, at 190° C., in analogy to examples IE1 to IE10. The resulting films were tested according to the DIN 4102 B2 standard, and additionally the fire time and fire height were determined.

(18) TABLE-US-00005 Film Burn Flame thick- DIN times Fire retardant ness 4102 [in height Examples composition.sup.a [mm] B2 seconds] [mm] CE1 No addition 0.35 Fail Complete Complete combustion combustion IE1 2% A 0.36 Pass 0 47 5% PCO 910 IE2 2% A 0.36 Pass 0 39 8% PCO 910

(19) The polymer films comprising the inventive compounds meet the B 4102 B2 standard, in contrast to the comparative example.