Search

EP-4739721-A1 - A SOLVENT-FREE POLYURETHANE DISPERSION BASED ON POLYTRIMETHYLENE ETHER GLYCOL

EP4739721A1EP 4739721 A1EP4739721 A1EP 4739721A1EP-4739721-A1

Abstract

The present invention relates to polyurethanes and polyurethane dispersions based on polyethers obtainable from renewable sources, particularly biomass.

Inventors

  • CHU, Yun
  • YU, Mingming
  • TANG, Shifeng
  • JIANG, Changjing
  • LI, YUAN
  • YIN, Fei
  • FAN, Zhirong
  • ZHU, Yingdan

Assignees

  • Covestro Deutschland AG

Dates

Publication Date
20260513
Application Date
20240703

Claims (13)

  1. Polyurethane obtained or obtainable by reacting a) 25 to 50 wt. -%of at least one polytrimethylene ether glycol (PO3G) having a number-average molecular weight between 400 and 4,000 g/mol; b) 20 to 25 wt. -%of at least one polycarbonate polyol or polycarbonate polyester polyol; c) 10 to 30 wt. -%of at least one aliphatic polyisocyanate; d) 0.5 to 2.5 wt. -%of at least one ionic or potentially ionic hydrophilizing agent; and e) 1 to 3 wt. -%at least one monofunctional hydrophilic polyether; wherein percentages are based on the total mass of the polyurethane.
  2. The polyurethane of claim 1, wherein the aliphatic polyisocyanate is selected from the group consisting of 1, 4-diisocyanatobutane (BDI) , 1, 5-diisocyanatopentane (PDI) , 1, 6-diisocyanatohexane (HDI) , 2-methyl-1, 5-diisocyanatopentane, 1, 5-diisocyanato-2, 2-dimethylpentane, 2, 2, 4-or 2, 4, 4-trimethyl-1, 6-diisocyanatohexane, 1, 10-diiisocyanatodecane, 1, 3-and 1, 4-diisocyanatocyclohexane, 1, 4-diisocyanato-3, 3, 5-trimethylcyclohexane, 1, 3-diisocyanato-2-methylcyclohexane, 1, 3-diisocyanato-4-methylcyclohexane, 1-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate; IPDI) , 1-isocyanato-1-methyl-4 (3) -isocyanatomethylcyclohexane, 2, 4’-and 4, 4'-diisocyanatodicyclohexylmethane (H12MDI) , 1, 3-and 1, 4-bis (isocyanatomethyl) cyclohexane, bis (isocyanatomethyl) norbornane (NBDI) , 4, 4'-diisocyanato-3, 3'-dimethyldicyclohexylmethane and oligomeric polyisocyanates comprising the aforementioned diisocyanates.
  3. The polyurethane of claim 2, wherein the aliphatic polyisocyanate is an oligomeric polyisocyanate comprising of at least one of the diisocyanates selected from the group consisting of 1, 4-diisocyanatobutane (BDI) , 1, 5-diisocyanatopentane (PDI) , 1, 6-diisocyanatohexane (HDI) , 2-methyl-1, 5-diisocyanatopentane, 1, 5-diisocyanato-2, 2-dimethylpentane, 2, 2, 4-or 2, 4, 4-trimethyl-1, 6-diisocyanatohexane, 1, 10-diiisocyanatodecane, 1, 3-and 1, 4-diisocyanatocyclohexane, 1, 4-diisocyanato-3, 3, 5-trimethylcyclohexane, 1, 3-diisocyanato-2-methylcyclohexane, 1, 3-diisocyanato-4-methylcyclohexane, 1-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate; IPDI) , 1-isocyanato-1-methyl-4 (3) -isocyanatomethylcyclohexane, 2, 4’-and 4, 4'-diisocyanatodicyclohexylmethane (H12MDI) , 1, 3-and 1, 4-bis (isocyanatomethyl) cyclohexane, bis (isocyanatomethyl) norbornane (NBDI) and 4, 4'-diisocyanato-3, 3'-dimethyldicyclohexylmethane.
  4. The polyurethane of any one of claims 1 to 3 comprising a polycarbonate polyol obtained or obtainable by reacting a first compound selected from the group consisting of alkyl carbonates and aryl carbonates with at least one second compound selected from the group consisting of 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 1, 6-hexanediol and 2, 2-dimethyl-1, 3-propanediol and/or a copolymer of polycaprolactone and polycarbonate obtained or obtainable by reacting a first compound selected from the group consisting of alkyl carbonates and aryl carbonates with at least one second compound selected from the group consisting of 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 1, 6-hexanediol and 2, 2-dimethyl-1, 3-propanediol.
  5. The polyurethane of any one of claims 1 to 4, wherein the polytrimethylene ether glycol (PO3G) as defined by formula (I) HO [CH 2 CH 2 CH 2 O] n H (I) Wherein n stands for an integer between 424 and 3962.
  6. The polyurethane of any one of claims 1 to 5, wherein the monofunctional hydrophilic polyether is a polyoxyalkylene ether containing based on the total mass of the monofunctional hydrophilic polyether a proportion of 30%by weight to 100%by weight of units derived from ethylene oxide.
  7. Aqueous polyurethane dispersion comprising a polyurethane as defined by any one of claims 1 to 6.
  8. The aqueous polyurethane dispersion of claim 7, wherein the content of acrylates does not exceed 10 wt. -%of the total mass of the solid body in the aqueous polyurethane dispersion.
  9. The aqueous polyurethane dispersion of claim 7 or 8 having a content of organic solvents not exceeding 1 wt. -%based on the total mass of the aqueous polyurethane dispersion.
  10. Article coated with the polyurethane defined in any one of claims 1 to 6.
  11. The coated article of claim 10, wherein the article is selected from the group consisting of fabric, yarn, paper, film and synthetic leather base.
  12. Foam or sheet made of the polyurethane defined in any one of claims 1 to 6.
  13. Method comprising the steps of a) Mixing at least one polytrimethylene etherglycol having a number-average molecular weight between 400 and 4,000 g/mol, at least one polycarbonate polyol or polycarbonate polyester polyol, at least one aliphatic polyisocyanate, optionally at least one potentially ionic hydrophilizing agent and at least one monofunctional hydrophilic polyether; b) Reacting the mixture obtained in method step a) to form a polyurethane; c) Adding acetone to dissolve the polyurethane before, during or after step b) , but before method steps d) and e) ; d) Optionally adjusting the pH of the mixture so that the potentially ionic hydrophilizing agent is converted into its ionic form; e) Reacting the polyurethane obtained in method step b) , polyurethane solution obtained in method step c) or neutralized polyurethane obtained in method step d) with amine functional small molecules (molecular weight between 60 and 400 g/mol) to form a polyurethane-urea; the said amine functional small molecules further contains an anionic compound, preferred an amino functional sulphonate or carboxylate; the said amino functional small molecules can be dissolved in acetone or water before adding; f) Adding water to the mixture obtained in method step d) or adding the mixture obtained in method step d) to water; and f) Removing the acetone by distillation so that an aqueous polyurethane dispersion is obtained.

Description

A solvent-free polyurethane dispersion based on polytrimethylene ether glycol The present invention relates to polyurethanes and polyurethane dispersions based on polyethers obtainable from renewable sources, particularly biomass. Polyurethane dispersions are widely used in coating applications. As compared to solvent-based polyurethane coating compositions they are more sustainable because they do not contain organic solvents which either evaporate and are released into the environment or must be burned in order to prevent the release. However, the polyurethanes themselves are currently to a large part based on raw materials derived from fossil sources, especially oil. Thus, there is a need to develop polyurethanes which themselves are based on renewable raw materials such as biomass. In order to supplant the polyurethanes currently in use these new polyurethanes should be suitable for making coatings with similar or improved properties. Polyurethanes are obtained by reacting a polyol component with a polyurethane component. The polyol component may be a polyester polyol, a polycarbonate polyol or a polyether polyol. 1, 3-propanediol may be obtained by microbial fermentation from biomass and reacted to polytrimethylene ether glycol (PO3G) . US 2008/0039582 describes a polyurethane dispersion comprising this compound as polyol. The polyurethane dispersions according to US 2008/0039582 contained residual concentrations of 1-methyl-2-pyrrolidinone, an organic solvent. Moreover, resistance against certain chemicals left room for improvement. Therefore, the problem solved by the present invention could be defined as providing solvent-free polyurethane dispersions which can be used to produce polyurethane coatings with a high degree of chemical resistance. This problem is solved by the embodiments defined by the claims and in this description below. In a first embodiment, the present invention relates to a polyurethane obtained or obtainable by reacting a) 25 to 50 wt. -%of at least one polytrimethylene ether glycol (PO3G) having a number-average molecular weight between 400 and 4,000 g/mol; b) 20 to 25 wt. -%of at least one polycarbonate polyol or polycarbonate polyester polyol; c) 10 to 30 wt. -%of at least one aliphatic polyisocyanate; d) 0.5 to 2.5 wt. -%of at least one potentially ionic hydrophilizing agent; and e) 1 to 3 wt. -%at least one monofunctional hydrophilic polyether; wherein percentages are based on the total mass of the polyurethane. The term “polytrimethylene ether glycol” preferably refers to a compound defined by formula (I) below: HO [CH2CH2CH2O] nH (I) Wherein in n stand for an integer between 424 and 3962. It is preferably derived from 1, 3-propanediol by polycondensation. The person skilled in the art is aware that compounds used for technical purposes may not be absolutely pure. Therefore, the term PO3G also refers to compounds deviating from the compound defined by general formula (I) due to the presence of other diols or triols in the reaction mixture provided that at least 90 wt. -%, preferably at least 95 wt. -%, more preferably at least 98 wt. -%and most preferably at least 99.5 wt. -%of the molecule are derived from 1, 3-propanediol. In principle, all polycarbonate and polycarbonate polyester polyols common in the field of polyurethane chemistry may be used. Preferred polycarbonate and polycarbonate polyester polyols have a number average molecular weight between 1000 and 3000 g/mol. Preferred polycarbonate polyols are obtained by the reaction of diols and aryl carbonates, or diols and alkyl carbonates or diols and mixtures of aryl and alkyl carbonates. A preferred aryl carbonate is diphenyl carbonate. A preferred alkyl carbonate is dimethyl carbonate. Preferably, the diol is selected from the group consisting of 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol and 2, 2-dimethyl-1, 3-propanediol. A preferred polycarbonate polyol is obtained or obtainable from the reaction of dimethyl carbonate and 1, 6-hexanediol. Preferred polycarbonate polyester polyols are copolymers of polycaprolactone and polycarbonate obtained or obtainable from the reaction of dimethyl carbonate and 1, 6-hexanediol. The term “aliphatic polyisocyanate” refers to any compound having at least two isocyanate groups linked to sp3-hybridized carbon atoms. It is to be understood that this definition includes compounds, wherein the sp3-hybridized carbon atom is linked to an aromatic ring. When general reference is made in this application to "polyisocyanates" , this means monomeric and/or oligomeric polyisocyanates alike. For understanding many aspects of the invention, however, it is important to distinguish between monomeric diisocyanates and oligomeric polyisocyanates. When reference is made here to "oligomeric polyisocyanates" , this means polyisocyanates formed from at least two monomeric diisocyanate molecules, i.e. compounds that constitute or contain a reaction