FLAME-RETARDANT POLYMER; METHOD FOR PREPARING IT AND THERMOPLASTIC POLYMER COMPOSITION COMPRISING IT

Abstract

The invention relates to a polymer which is useful as flame-retardant polymer. The invention also relates to a method of preparing said polymer and to a thermoplastic polymer composition comprising said polymer. The thermoplastic polymer composition can be used for the production of molded articles having excellent flame-retardant properties in order to ensure adequate fire protection.

Claims

1. A polymer, obtainable by polycondensation of: a) at least one phosphorous-containing monomer selected from adducts of: a1) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and/or nuclear substituted DOPO derivatives, with a2) at least one unsaturated di- or multivalent carboxylic acid or ester or anhydride thereof; b) at least one phosphorous-containing di- or multivalent alcohol; and c) optionally other monomers with the exception of unsaturated di- or multivalent carboxylic acids.

2. The polymer according to claim 1 having a phosphorous content of above 7.0% by weight each of the total weight of the polymer.

3. The polymer according to claim 1, wherein the phosphorous-containing monomer a) is selected from a compound represented by the following general formula (I): ##STR00010## wherein n and m are integers from 0 to 4; R.sub.1 and R.sub.2 are independently selected from the group consisting of alkyl, alkoxy, aryl, aryloxy and aralkyl, wherein, if more than one of R.sub.1 and/or R.sub.2 are present, each of these substituents can be identical or different to each other; and R.sub.3 denotes a residue derived from the unsaturated di- or multivalent carboxylic acid or ester or anhydride thereof.

4. The polymer according to claim 3, wherein R.sub.1 and R.sub.2 are independently selected from C.sub.1-8 alkyl and C.sub.1-8 alkoxy; and n and m are independently 0 or 1.

5. The polymer according to claim 1, wherein the unsaturated di- or multivalent carboxylic acid or ester or anhydride thereof is a divalent carboxylic acid or ester or anhydride thereof which is selected from the group consisting of itaconic acid, maleic acid, fumaric acid, endomethylene tetrahydrophthalic acid, citraconic acid, mesaconic acid, and tetrahydrophthalic acid and esters and anhydrides thereof.

6. The polymer according to claim 5, wherein the unsaturated divalent carboxylic acid is selected from the group consisting of itaconic acid, maleic acid and anhydrides thereof.

7. The polymer according to claim 1, wherein the phosphorous-containing di- or multivalent alcohol b) is a phosphine oxide.

8. The polymer according to claim 7, wherein the phosphine oxide bears at least two hydroxy groups being attached to the phosphorous atom via the same or different hydrocarbon residues.

9. The polymer according to claim 8, wherein the hydrocarbon residues of the phosphine oxide are independently selected from the group consisting of alkyl, aryl, alkylaryl, alkoxyaryl, aralkyl and aryloxyalkyl.

10. The polymer according to claim 7, wherein the phosphine oxide is a compound represented by the following general formula (II): ##STR00011## wherein R.sub.4 represents C.sub.1-4 alkyl or aryl and x and y are independently 2 or 3.

11. The polymer according to claim 10, wherein R.sub.4 is isobutyl and x and y are both 3.

12. The polymer according to claim 1 comprising repeating units represented by the following general formula (III): ##STR00012## wherein R.sub.4 represents C.sub.1-4 alkyl or aryl and x and y are independently 2 or 3.

13. A method of preparing a polymer according to claim 1, wherein the method comprises the steps of: a) reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and/or nuclear substituted derivatives thereof with at least one unsaturated di- or multivalent carboxylic acid or ester or anhydride thereof to obtain a first phosphorous-containing monomer; b) reacting the first phosphorous-containing monomer obtained in step a) with at least one phosphorous-containing di- or multivalent alcohol, and optionally other monomers with the exception of unsaturated di- or multivalent carboxylic acids; and c) optionally carrying out the reaction in step b) in the presence of at least one monovalent carboxylic acid and/or monovalent alcohol and /or reacting the polymer obtained in step b) with at least one monovalent carboxylic acid and/or monovalent alcohol to obtain an end-capped polymer.

14. A thermoplastic polymer composition comprising: a thermoplastic polymer; and a polymer according to claim 1, wherein the polymer composition comprises from about 2% to about 20% by weight of the polymer according to claim 1 based on the total weight of the polymer composition, and wherein the thermoplastic polymer is selected from the group consisting of polyamides, polyphthalamides, polyesters including unsaturated polyester resins, polysulfones, polyimides, polyolefins, polyacrylates, polyether etherketones, acrylnitril butadiene styrenes (ABS), polyurethanes, polystyrenes, polycarbonates, polyphenylene oxides, phenolic resins and mixtures thereof.

15. The polymer of claim 1, wherein the polymer is used as a flame-retardant polymer.

16. The polymer according to claim 9, wherein the hydrocarbon residues of the phosphine oxide are independently selected from the group consisting of C.sub.1-4 alkyl, phenyl, naphthalenyl, mono- or di-(C.sub.1-4 alkoxy)phenyl and mono- or di-(C.sub.1-4 alkoxy)naphthalenyl.

Description

EXAMPLES

[0087] The following starting materials were used for production:

[0088] PA66 (Stabamid 26AE1)

[0089] Flame retardant: Ukanol FR 80 PU 30 (Schill+Seilacher), containing 8.0%w of phosphorus according to technical data sheet. Ukanol FR 80 is used in US 2013/0136911 A1 as flame retardant. It has the following chemical structure:

##STR00006##

[0090] (6-oxide-6H-dibenzo (c,e) (1,2) oxa-phosphorin-6-yl) butanedioic acid (Lunastab DDP, CAS [63562-33-4])

[0091] bis(3-hydroxypropyl)isobutylphosphine oxide (Cyagard RF 1243 from Solvay)

[0092] The following measuring methods were used:

[0093] Melting, crystallization and glass transition temperatures determined by DSC, at 10° C./min.

[0094] Onset of thermal degradation temperature determined by TGA, at 10° C./min under nitrogen flow.

[0095] Phosphorus content by ICP/OES after sulfonitric mineralization.

[0096] Viscosity number in formic acid 90%, according to ISO 307.

[0097] UL 94-V with 125×13×3 mm samples.

[0098] The acid and hydroxyl numbers were respectively determined by titration in pyridine with NaOH, directly or after reaction with phtalic anhydride.

[0099] Phosphorous containing polyester

Example 1

Production of a Phosphorous Containing Polyester According to the Invention

[0100] 276.4 g (0.80 mol) of Lunastab DDP represented by the following formula:

##STR00007##

and 178.2 g (0.80 mol) of Cyagard RF 1243 represented by the following formula:

##STR00008##

were poured in a one-liter flask equipped with a mechanical stirrer with vacuum/nitrogen inlet and a distillation column followed by a condenser and an internal thermometer. The temperature was increased progressively to 160° C. under nitrogen, with continuous stiffing, and kept for 1 h at this temperature. The temperature was then slowly increased up to 240° C. and kept at this temperature for 3 h and the reaction water thereby produced was continuously removed by distillation. Then the heater was stopped and the adduct was let to cool down to room temperature. The day after the temperature was progressively increased to 160° C. under nitrogen and 0.040 g of tetra-n-butyl titanate in solution in 0.455 g of monoethylene glycol was introduced in the adduct. Then the temperature was increased progressively to 240° C. The column was then removed, and the pressure was reduced to 10 mbar for 4 h, under continuous stiffing. After cooling, a brown glassy polymer was obtained which contained polyester chains represented by the following formula:

##STR00009##

wherein n denotes the mole fraction of the polyester repeating unit. The polymer thus obtained had the following analytical data: The amorphous polyester had a glass transition temperature of 70° C., and a thermal degradation onset of 352° C.

[0101] The acid and hydroxyl numbers were respectively 25 mgKOH/g and below 3 mgKOH/g.

[0102] The .sup.31P NMR was in agreement with the polyester structure, with two chemical shifts at 41 ppm and 59 ppm.

[0103] The phosphorous content was 11% w.

[0104] Production of PA66 based compounds

Example 2

Production of Flame-Retardant PA66 Compound

[0105] The PA66 pellets were cryogenic grinded below 1.5 mm and the powder was then dried at 90° C. in a vacuum oven for one night. The polyester from example 1 was roughly dry grinded.

[0106] Dry blend was then prepared with the powders of PA66 and polyester according to Example 1 with the corresponding ratio 91.4%/8.6% by weight, for 1% by weight end concentration of phosphorous.

[0107] The production of the compound was effected by melt blending with a twin-screw extruder of diameter D=11 mm (L/D =40) equipped by a water cooling bath and a pelletizer. The melt temperature was 260-290° C.

[0108] The compound thus obtained had the following analytical data: The melting and crystallization temperatures were respectively 259° C. and 233° C.

[0109] The phosphorus content was 1% w.

[0110] The viscosity number was 115 mL/g.

Example 3

Production of a Phosphorous Containing Polyester According to the Invention

[0111] Similarly to example 1, but with 276.4 g (0.80 mol) of Lunastab DDP and 201.7 g (0.91 mol) of Cyagard RF 1243. After cooling, a yellow glassy polymer was obtained, with the following analytical data:

[0112] The amorphous polyester had a glass transition temperature of about 65° C., and a thermal degradation onset of 351° C.

[0113] The acid and hydroxyl numbers were respectively 15 mgKOH/g and below 3 mgKOH/g.

[0114] The .sup.31P NMR was in agreement with the polyester structure, with two chemical shifts at 41 ppm and 59 ppm.

[0115] The phosphorous content was 12% w.

Example 4

Production of a Phosphorous Containing Polyester According to the Invention

[0116] Similarly to example 1, but with 276.4 g (0.80 mol) of Lunastab DDP and 216.2 g (0.97 mol) of Cyagard RF 1243. After cooling, a pale yellow glassy polymer was obtained, with the following analytical data:

[0117] The amorphous polyester had a glass transition temperature of about 60° C., and a thermal degradation onset of 353° C.

[0118] The acid and hydroxyl numbers were respectively 12 mgKOH/g and 6 mgKOH/g.

[0119] The .sup.31P NMR was in agreement with the polyester structure, with two chemical shifts at 41 ppm and 59 ppm. The phosphorous content was 12% w.

Comparative Example 1

Production of a PA66 Compound

[0120] Done similarly to Example 2 with 100% by weight of PA66.

[0121] The compound thus obtained had the following analytical data:

[0122] The melting and crystallization temperatures were respectively 263° C. and 234° C.

[0123] The viscosity number was 131 mL/g.

Comparative Example 2

Production of a Phosphorous Containing PA66 Compound

[0124] Done similarly to Example 2 with the component ratio PA66/Ukanol FR 80 as follow 87.5%/12.5% by weight, for 1% by weight end concentration of phosphorous. The Ukanol FR 80, already in powder, was used as such.

[0125] The compound thus obtained had the following analytical data:

[0126] The melting and crystallization temperatures were respectively 259° C. and 233° C.

[0127] The phosphorus content was 1% w.

[0128] The viscosity number was 112 mL/g.

Flame-Retardancy Test

[0129] Prior to flame-retardancy test, the compounds were shaped by melt compression. The comparative examples were selected such that a pure PA66 system (Comp. ex. 1) and a phosphorous containing PA66 system (Comp. ex. 2) were tested. At the same time, example 2 according to the invention was tested, which comprised both PA66 and the flame retardant polyester of the invention (Ex. 1).

[0130] The experimental data which verify the positive properties of the described compounds are compiled in Table 1.

TABLE-US-00001 TABLE 1 Comp. Ex. 1 Comp. Ex. 2 Ex. 2 Composition PA66 (% by weight) 100.0% 87.5% 91.4% FR80 (% by weight) 12.5% Example 1 (% by weight) 8.6% Properties VN (mL/g) 131 112 115 Tm (° C.) 263 259 259 Tc (° C.) 234 233 233 P-content (% by weight) 0 1 1 UL 94-V rating V2 V2 V0 t.sub.1 (s) .sup.a) 2 2 1 t.sub.2 (s) .sup.b) 1 2 1 t.sub.f (s) .sup.c) 16 19 11 Cotton ignition Yes Yes No Burn up to the holding clamp No No No a) Flaming combustion time after first application of the test flame. b) Flaming and glowing combustion time after the second removal of the test flame. c) Total flaming combustion time for the 10 flame applications for each set of 5 specimens.

[0131] Correspondingly, only example 2, containing the halogen-free flame-retardant polyester according to the invention, has flame-retardant properties which fulfill V0 requirement, the best flame test rating according to UL 94-V, for 3 mm thick samples. In particular the specimens do not drip flaming particles that ignite the dry absorbent surgical cotton located 300 mm below the test specimen.

[0132] It can be deduced from comparative example 2 in the table that using Ukanol FR 80 which is known as halogen-free polyester flame retardant in the prior art leads to insufficient flame-retardant properties, even with a higher load of additive, since the specimens drip flaming particles that ignite the dry absorbent surgical cotton located 300 mm below the test specimen. Comparative example 1 with virgin PA66 behaves similarly. Moreover they both show increased total flaming combustion time compared to the example according to the invention.

[0133] It can be concluded from these comparative tests that only with the halogen-free flame-retardant polyester of the invention is the flame test according to UL 94-V V0 rated, while thermal characteristics of PA66 are maintained.

Washing Resistance Test

[0134] For the resistance to washing, 2g of pellets obtained in Example 2 or in Comparative example 2 were mixed in 75 g of demineralized water, for 3 h at 95° C., under reflux. Then the pellets were filtered and dried for 2 nights at 90° C., under vacuum. Finally, the remaining phosphorous content was measured. In both cases the phosphorous relative variation was about +/−1% w, which is below the incertitude of the measure itself. Thus no phosphorous content extraction was noticed during the washing resistance test in both cases.