Use of polyesters having inherent flame protection in adhesives and sealants

Abstract

The present invention relates to the use of polyesters with inherent flame retardancy as or in adhesives, sealants and coatings, to polyesters with inherent flame retardancy and to processes for production thereof.

Claims

1. A process for making a flame-retardant hot-melt adhesive, the process comprising mixing a mixture comprising a flame-retardant polyester to obtain the flame-retardant hot-melt adhesive, wherein: the flame-retardant polyester is formed from adipic acid, 1,6-hexanediol, neopentyl glycol, and a diol of formula (I): ##STR00004## where R is a saturated linear or branched alkyl moiety having from 1 to 10 C atoms, and A and B are identical or different and are saturated linear or branched alkylene groups having from 1 to 10 C atoms or are mono- or polyalkylene glycol groups; and no other diols or polyols having ether groups in addition to the diol of the formula (I) are used to form the flame-retardant polyester.

2. The process of claim 1, wherein the flame-retardant hot-melt adhesive is a reactive hot-melt adhesive.

3. The process of claim 1, wherein A and B are identical or different and are mono- or polyalkylene glycol groups, which are ethylene glycol groups of formula —CH.sub.2—CH.sub.2(—O—CH.sub.2—CH.sub.2).sub.n— or propylene glycol groups of formula —CH.sub.2—CHCH.sub.3(—O—CH.sub.2—CHCH.sub.3).sub.n—, where n is an integer from 1 to 10.

4. The process of claim 1, wherein the diol of the formula (I) is bis[2-(2-hydroxyethoxy) ethyl] methanephosphonate.

5. An adhesive, sealant or coating, comprising a polyester formed from adipic acid, 1,6-hexanediol, neopentyl glycol, and a diol of formula (I): ##STR00005## where R is a saturated linear or branched alkyl moiety having from 1 to 10 C atoms, and A and B are identical or different and are saturated linear or branched alkylene groups having from 1 to 10 C atoms or are mono- or polyalkylene glycol groups; and no other diols or polyols having ether groups in addition to the diol of the formula (I) are used to form the polyester.

6. The adhesive, sealant or coating of claim 5, which is a hot-melt adhesive.

7. The adhesive, sealant or coating of claim 6, which is a reactive hot-melt adhesive.

8. A polyester, formed from adipic acid, 1,6-hexanediol, neopentyl glycol, and a diol of formula (I): ##STR00006## where R is a saturated linear or branched alkyl moiety having from 1 to 10 C atoms; and A and B are identical or different and are saturated linear or branched alkylene groups having from 1 to 10 C atoms or are mono- or polyalkylene glycol groups, wherein no other di- or polycarboxylic acid or a derivative thereof in addition to adipic acid is used to form the polyester.

9. The polyester of claim 8, wherein A and B are identical or different and are mono- or polyalkylene glycol groups, which are ethylene glycol groups of the general formula —CH.sub.2—CH.sub.2(—O—CH.sub.2—CH.sub.2).sub.n— or propylene glycol groups of formula —CH.sub.2—CHCH.sub.3(—O—CH.sub.2—CHCH.sub.3).sub.n—, where n is an integer from 1 to 10.

10. The polyester of claim 8, wherein the diol of the formula (I) is bis[2-(2-hydroxyethoxy)ethyl] methanephosphonate.

11. The process of claim 1, wherein a proportion of the diol of the formula (I) is from 4 to 12 mol % based on an entirety of the di- or polyols in the mixture.

12. The process of claim 1, wherein the mixing takes place in a melt.

13. A process for making a flame-retardant hot-melt adhesive, the process comprising mixing a mixture comprising a flame-retardant polyester and at least one of an isocyanate and a polyisocyanate to obtain the flame-retardant hot-melt adhesive, wherein: the flame-retardant polyester is formed from at least one di- or polycarboxylic acid and at least one di- or polyol; the flame-retardant polyester is formed from at least one diol of formula (I): ##STR00007## where R is a saturated linear or branched alkyl moiety having from 1 to 10 C atoms, and A and B are identical or different and are saturated linear or branched alkylene groups having from 1 to 10 C atoms or are mono- or polyalkylene glycol groups; and no other diols or polyols having ether groups are present in addition to the diol of the formula (I) in the flame-retardant polyester.

14. The process of claim 13, wherein a ratio of OH:NCO in the mixture is from 1:1.2 to 1:3.

15. A process for making a flame-retardant hot-melt adhesive, the process comprising mixing a mixture comprising a flame-retardant polyester and an organosilane to obtain the flame-retardant hot-melt adhesive, wherein: the flame-retardant polyester is formed from at least one di- or polycarboxylic acid and at least one di- or polyol; the flame-retardant polyester is formed from at least one diol of formula (I): ##STR00008## where R is a saturated linear or branched alkyl moiety having from 1 to 10 C atoms, and A and B are identical or different and are saturated linear or branched alkylene groups having from 1 to 10 C atoms or are mono- or polyalkylene glycol groups; and no other diols or polyols having ether groups are present in addition to the diol of the formula (I) in the flame-retardant polyester.

16. An adhesive, sealant, or coating, comprising a polyester formed from at least one di- and/or polycarboxylic acid and at least one di- and/or polyol, and at least one of an isocyanate and a polyisocyanate, wherein the polyester is formed from at least one diol of formula (I): ##STR00009## where R is a saturated linear or branched alkyl moiety having from 1 to 10 C atoms, and A and B are identical or different and are saturated linear or branched alkylene groups having from 1 to 10 C atoms or are mono- or polyalkylene glycol groups; and no other diols or polyols having ether groups are present in addition to the diol of the formula (I) in the polyester.

17. An adhesive, sealant, or coating, comprising: a polyester formed from at least one di- and/or polycarboxylic acid and at least one di- and/or polyol, and an organosilane, wherein the polyester is formed from at least one dial of formula (I): ##STR00010## where R is a saturated linear or branched alkyl moiety having from 1 to 10 C atoms, and A and B are identical or different and are saturated linear or branched alkylene groups having from 1 to 10 C atoms or are mono- or polyalkylene glycol groups; and no other diols or polyols having ether groups are present in addition to the diol of the formula (I) in the polyester.

18. The polyester of claim 8, which has a functionality of 1.0 to 3.0.

19. The process of claim 13, wherein the flame-retardant hot-melt adhesive is a reactive hot-melt adhesive.

20. The process of claim 13, wherein A and B are identical or different and are mono- or polyalkylene glycol groups, which are ethylene glycol groups of formula —CH.sub.2—CH.sub.2(—O—CH.sub.2—CH.sub.2).sub.n— or propylene glycol groups of formula —CH.sub.2—CHCH.sub.3(—O—CH.sub.2—CHCH.sub.3).sub.n—, where n is an integer from 1 to 10.

21. The process of claim 13, wherein the diol of the formula (I) is bis[2-(2-hydroxyethoxy) ethyl] methanephosphonate.

22. The process of claim 15, wherein the flame-retardant hot-melt adhesive is a reactive hot-melt adhesive.

23. The process of claim 15, wherein A and B are identical or different and are mono- or polyalkylene glycol groups, which are ethylene glycol groups of formula —CH.sub.2—CH.sub.2(—O—CH.sub.2—CH.sub.2).sub.n— or propylene glycol groups of formula —CH.sub.2—CHCH.sub.3(—O—CH.sub.2—CHCH.sub.3).sub.n—, where n is an integer from 1 to 10.

24. The process of claim 15, wherein the diol of the formula (I) is bis[2-(2-hydroxyethoxy) ethyl] methanephosphonate.

25. The adhesive, sealant or coating of claim 16, which is a hot-melt adhesive.

26. The adhesive, sealant or coating of claim 25, which is a reactive hot-melt adhesive.

27. The adhesive, sealant or coating of claim 17, which is a hot-melt adhesive.

28. The adhesive, sealant or coating of claim 27, which is a reactive hot-melt adhesive.

Description

EXAMPLES

Example 1

Not According to the Invention

(1) Production of Polyester P1:

(2) 951 g of adipic acid (6.51 mol) are melted together with 378 g of neopentyl glycol and 429 g of 1,6-hexanediol (in each case 3.63 mol) under nitrogen in a flask with distillation head. At a temperature of 240° C., most of the water of reaction is removed by distillation within about 4 to 6 hours. 0.15 g (0.01 percent by weight) of a titanium catalyst is then added, and the pressure in the apparatus is lowered in stages as far as 10 mbar. Once the desired hydroxy number range and acid number range were reached, the reaction was ended.

(3) The hydroxy number of the polyester P1 is 40 mg KOH/g, measured in accordance with DIN 53240-2, and its acid number is 1 mg KOH/g, measured in accordance with DIN EN ISO 2114.

Example 2

Inventive

(4) Production of Polyester 2:

(5) 913 g of adipic acid (6.25 mol) are melted together with 349 g of neopentyl glycol and 396 g of 1,6-hexanediol (in each case 3.36 mol) under nitrogen in a flask with distillation head. 109 g (0.43 mol) of Exolit OP 560 (Clariant, according to formula I, where R═CH.sub.3, A, B=oligoethylene glycol) are added as additional comonomer.

(6) This corresponds to 0.9% by weight phosphorus content, based on the polyester. The conduct of the reaction is analogous to that of Example 1. Once the desired hydroxy number range and acid number range were reached, the reaction was ended.

(7) The incorporation of the reactive flame retardant into the polyester chain can be demonstrated by means of .sup.31P phosphorus NMR. The signal at 33 ppm is split by the covalent bonding to the polyester and has a slight shift towards high field. The hydroxy number of the polyester P2 is 40 mg KOH/g, measured in accordance with DIN 53240-2, and its acid number is 1 mg KOH/g, measured in accordance with DIN EN ISO 2114.

(8) Application as Adhesive:

(9) Production of Moisture-Curing Hot-Melt Adhesives

RHM Example 1

Not According to the Invention

(10) 250 g of the polyester P1 are melted in a 500 ml flask with flat round flange and dried in vacuo at 130° C. 49 g of diphenylmethane 4,4′-diisocyanate (MDI), corresponding to an OH/NCO ratio of 1/2.2, are then added and quickly homogenized. The mixture is stirred under inert gas at 130° C. for 45 minutes to give complete reaction of the reactants. The moisture-curing hot-melt adhesive is then discharged.

RHM Example 2

Not According to the Invention

(11) 250 g of the polyester P1 are melted in a 500 ml flask with flat round flange. After addition of 34 g of bisphenol A bis(diphenyl phosphate), the mixture is dried in vacuo at 130° C. 49 g of diphenylmethane 4,4′-diisocyanate (MDI), corresponding to an OH/NCO ratio of 1/2.2, are then added and quickly homogenized. The mixture is stirred under inert gas at 130° C. for 45 minutes to give complete reaction of the reactants. The moisture-curing hot-melt adhesive is then discharged. Addition of a phosphorus-containing flame retardant as additive, for example bisphenol A bis(diphenyl phosphate), can give 1% by weight phosphorus content in the formulation.

RHM Example 3

According to the Invention

(12) The production process takes place by analogy with RHM Example 1 with polyester 2 instead of polyester 1.

(13) Characterization:

(14) a) Flame Retardancy:

(15) Flame retardancy properties are determined in accordance with the test standard UL 94 on test specimens made of a hardened RHM film of thickness from 0.5 to 1 mm. Hardening was achieved in a cabinet under controlled conditions of temperature and humidity within 7 days at 20° C. and 65% relative humidity.

(16) Results:

(17) RHM 1 exhibits no flame retardancy properties.

(18) Burning drops ignite a cotton pad located under the specimen, the corresponding vertical flame retardancy classification being V-2.

(19) RHM 2 and RHM 3 are least flammable and achieve the highest classification V-0.

(20) b) Adhesive Properties:

(21) Adhesive properties were determined on various substrates in accordance with the DIN EN 1465 method after a hardening time of 7 days at 20° C. and 65% relative humidity.

(22) TABLE-US-00001 TABLE 1 Tensile shear strength in N/mm.sup.2 ABS PET PVC RHM 1 7 7 12 RHM 2 6 3 6 RHM 3 10 6 12

(23) c) Migration Resistance:

(24) In order to determine migration resistance, the percentage loss of mass was determined after 11 hours of extraction of the hardened reactive hot-melt adhesive in boiling acetone.

(25) The loss of mass is 11% for RHM 1, 22% for RHM 2 and 13% for RHM 3.

(26) The examples show that addition of a phosphorus-containing flame retardant as additive improves flame retardancy in comparison with a formulation without flame retardant. However, adhesive properties in relation to various substrates are drastically impaired. The relatively high loss of mass indicates that the flame retardant additive is leached out of the adhesive and can migrate.

(27) The use of polyesters with inherent flame retardancy in hot-melt adhesives ensures adequate flame retardancy, and also ensures adhesive properties that are comparable with those of conventional, non-flame-retardant formulations. The loss of mass is also comparable. This shows that the reactive flame retardant has covalent bonding to the polyester chains, and cannot migrate.