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EP-4055075-B1 - IMIDE-CONTAINING POLYESTER POLYOLS AND INTUMESCENT RIGID FOAMS

EP4055075B1EP 4055075 B1EP4055075 B1EP 4055075B1EP-4055075-B1

Inventors

  • LISKEY, Carl William
  • KAPLAN, WARREN A.
  • YOCIUS, Daniel

Dates

Publication Date
20260506
Application Date
20201105

Claims (15)

  1. A rigid polyurethane or polyisocyanurate foam which comprises a reaction product of: (a) a polyisocyanate; (b) a polyester polyol comprising recurring units of: (i) a phthalimide-containing polyacid; (ii) a phthalimide-containing polyol; or (iii) a combination of (i) and (ii); wherein the phthalimide-containing polyacid is a reaction product of trimellitic anhydride and an amino acid selected from the group consisting of glycine, alanine, phenylalanine, serine, threonine, aspartic acid, and glutamic acid, with exclusion of a reaction product of trimellitic anhydride and glycine if the polyester polyol comprises recurring units according to alternative (i); and wherein the phthalimide-containing polyol is a reaction product of an aliphatic aminoalcohol, a glycol or polyol, and trimellitic anhydride; or a reaction product of a bis(anhydride) and two molar equivalents of an aliphatic aminoalcohol; the polyester polyol having a hydroxyl value within the range of 150 to 800 mg KOH/g and an acid value within the range of 0.1 to 5 mg KOH/g; (c) water; (d) a surfactant; (e) a urethane catalyst, an isocyanurate catalyst, or both; (f) optionally, a blowing agent; and (g) optionally, a flame retardant.
  2. The rigid foam of claim 1 wherein the polyisocyanate is a polymeric MDI.
  3. The rigid foam of claim 1 wherein the phthalimide-containing polyacid is a diacid having the structure: wherein each of R 1 and R 2 is independently hydrogen, alkyl, hydroxyalkyl, haloalkyl, or alkoxy, with exclusion of R 1 and R 2 being hydrogen if the polyester polyol comprises recurring units according to alternative (i), and n has a value from 0 to 4.
  4. The rigid foam of claim 1 wherein the aminoalcohol is ethanolamine or 2-(2-aminoethoxy)ethanol.
  5. The rigid foam of claim 1 wherein the glycol is ethylene glycol, diethylene glycol, triethylene glycol, or combinations thereof.
  6. The rigid foam of claim 1 wherein the bis(anhydride) is pyromellitic dianhydride or has the formula: wherein L is an optional divalent linking group having a structure selected from -O-, -S-, -S(=O)-, -S(=O) 2 -, -C(=O)-, -C 2 -, -CH 2 -, -CH 2 -CH 2 -, -CH(CH 3 )-, - C(CH 3 ) 2 -, -C(CF 3 ) 2 -, -C(Ph)(CH 3 )-, and -CH(Ph)-.
  7. The rigid foam of claim 1 wherein the phthalimide-containing polyol is a diol having the structure: wherein each of m and n independently has an average value from 1 to 5.
  8. The rigid foam of claim 1 wherein the amount of phthalimide-containing polyacid or phthalimide-containing polyol incorporated into the polyester polyol is within the range of 10 to 50 wt.% based on the amount of polyester polyol.
  9. The rigid foam of claim 1 wherein the polyester polyol further comprises recurring units of one or more reactants selected from the group consisting of phthalic anhydride, maleic anhydride, itaconic anhydride, isophthalic acid, terephthalic acid, dimethyl terephthalate, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, and combinations thereof.
  10. The rigid foam of claim 1 wherein the polyester polyol further comprises recurring units of diethylene glycol.
  11. A polyester polyol comprising recurring units of: (a) terephthalic acid; (b) diethylene glycol; (c) a phthalimide-containing polyacid or a phthalimide-containing polyol; wherein the phthalimide-containing polyacid is a reaction product of trimellitic anhydride and an amino acid selected from the group consisting of glycine, alanine, phenylalanine, serine, threonine, aspartic acid, and glutamic acid, with exclusion of a reaction product of trimellitic anhydride and glycine; and wherein the phthalimide-containing polyol is a reaction product of an aliphatic aminoalcohol, a glycol or polyol, and trimellitic anhydride; or a reaction product of a bis(anhydride) and two molar equivalents of an aliphatic aminoalcohol; (d) optionally, 2 to 20 wt.%, based on the amount of polyester polyol, of a natural oil; (e) optionally, an anhydride, a diester, or a diacid other than terephthalic acid; and (f) optionally, a diol or polyol other than diethylene glycol; wherein the polyester polyol has a hydroxyl value within the range of 150 to 800 mg KOH/g and an acid value within the range of 0.1 to 5 mg KOH/g.
  12. The polyester polyol of claim 11 comprising at least 35 wt.% of terephthalic acid recurring units based on the combined amounts of (a) and (e) or comprising at least 55 wt.% of diethylene glycol recurring units based on the combined amounts of (b) and (f).
  13. The polyester polyol of claim 11 wherein the amount of phthalimide-containing polyacid or phthalimide-containing polyol incorporated into the polyester polyol is within the range of 10 to 50 wt.% based on the amount of polyester polyol.
  14. A blend comprising the polyester polyol of claim 11 and 1 to 20 wt.%, based on the amount of blend, of a nonionic surfactant, preferably 1 to 10 wt.%.
  15. A method comprising formulating a rigid polyurethane or polyisocyanurate foam by reacting: (a) a polyisocyanate; (b) a polyester polyol comprising recurring units of: (i) a phthalimide-containing polyacid; (ii) a phthalimide-containing polyol; or (iii) a combination of (i) and (ii); wherein the phthalimide-containing polyacid is a reaction product of trimellitic anhydride and an amino acid selected from the group consisting of glycine, alanine, phenylalanine, serine, threonine, aspartic acid, and glutamic acid, with exclusion of a reaction product of trimellitic anhydride and glycine if the polyester polyol comprises recurring units according to alternative (i); and wherein the phthalimide-containing polyol is a reaction product of an aliphatic aminoalcohol, a glycol or polyol, and trimellitic anhydride; or a reaction product of a bis(anhydride) and two molar equivalents of an aliphatic aminoalcohol; the polyester polyol having a hydroxyl value within the range of 150 to 800 mg KOH/g and an acid value within the range of 0.1 to 5 mg KOH/g; (c) water; (d) a surfactant; (e) a urethane catalyst, an isocyanurate catalyst, or both; (f) optionally, a blowing agent; and (g) optionally, a flame retardant.

Description

FIELD OF THE INVENTION The invention relates to phthalimide-containing polyester polyols and their use to produce rigid polyurethane or polyisocyanurate foams having improved heat resistance and intumescence. BACKGROUND OF THE INVENTION Rigid polyurethane (PU) or polyisocyanurate (PIR) foams are common insulation materials. The foams must pass well-defined, region-specific flammability tests. Flame retardants are incorporated into the foams to reduce flammability. However, common flame retardants are costly, and many of them-especially halogenated flame retardants-are under increasing regulatory pressure. Additionally, even with flame retardants, flammability requirements can be difficult to achieve. Polyester polyols are commonly used to produce rigid PU or PIR foams. Some polyols are better than others in imparting desirable flammability properties to foams; desirable properties include low mass loss, reduced smoke generation, and better char formation (i.e., better intumescence). In some cases, terephthalate polyesters have been used to improve foam flammability. Further improvements in flammability performance attributable to the polyester polyol are desirable. The improvements would allow formulators to achieve acceptable flammability properties with reduced levels of flame retardants and a reduced proportion of polyisocyanate. Additionally, thinner rigid foam insulation panels with good flame resistance could be made. Polyimides, i.e., polymers made, for example, by reacting a dianhydride (such as pyromellitic dianhydride) with an aromatic diamine or with a diisocyanate, are used in applications that require high thermal stability. Polyimides have not been used widely for building insulation because of their high cost and relatively poor insulating properties. Instead, they are used primarily in special applications such as electronics for which high thermal stability, chemical resistance, and excellent dielectric properties are needed. EP 3 492 503 A1 discloses a process for preparing hydroxyl-terminated polyester polyols and polyurethane prepared from said polyester polyols. The polyester polyols are obtained in a one-pot synthesis from amino acids and polyacid anhydrides in the presence of at least one di- and/or polyol with a molecular weight in the range of from 62 to 1000 g/mol. US 2005/0288405 A1 describes a copolymer composition comprising structural units derived from a substituted or unsubstitued diacid or diester, a substituted diol or unsubstituted diol and a diimide compound. Mighani, H.: Synthesis of Thermally Stable Polyesters (doi: 10.5772/39224) is a scientific article providing a general overview on different types of polyesters, including polyester-imides. WO 2021/030115 A discloses a polyurethane foam composition comprising a polyester polyol, an isocyanate, water, a surfactant and a catalyst. In one example, the polyester polyol is formed by reacting trimellitic anhydride, glycine, purified terephthalic acid, glycerin, PEG 200, triethylene glycol and diethylene glycol, wherein the polyester polyol is adjusted to an acid value of 1.3 mg KOH/g and an hydroxyl value of 250 mg KOH/g. The construction industry would benefit from the availability of polyester polyols having improved thermal stability and the ability to produce rigid PU and PIR foams having improved flammability properties. Desirable polyols would allow formulators of rigid foams to reduce their dependence on traditional flame retardants and high polyisocyanate contents for passing industry-standard flammability tests. Ideally, the polyols would be economical and easy to synthesize from readily available starting materials. SUMMARY OF THE INVENTION The object of the invention is solved by a rigid polyurethane or polyisocyanurate foam according to claim 1, a polyester polyol according to claim 11 and a method according to claim 15. In one aspect, the invention relates to a rigid polyurethane or polyisocyanurate foam according to claim 1. The foam comprises a reaction product of a polyisocyanate, a polyester polyol, water, a surfactant, a catalyst, and optional ingredients. The polyester polyol comprises recurring units of a phthalimide-containing polyacid, a phthalimide-containing polyol, or a combination thereof. In other aspects, the invention includes a polyester polyol according to claim 11 comprising recurring units of terephthalic acid, diethylene glycol, and a phthalimide-containing polyacid, a phthalimide-containing polyol, or their combination. In some aspects, the polyester polyol has a hydroxyl value within the range of 150 to 800 mg KOH/g and an acid value within the range of 0.1 to 5 mg KOH/g. The invention includes a method according to claim 15 which comprises formulating a rigid polyurethane or polyisocyanurate foam by reacting the polyisocyanate and the polyester polyol as described above with water, a surfactant, a catalyst, and optional ingredients. Rigid PU and PIR foams produced from the polyester pol