The present invention relates to a hyperbranched polyester-polyol of generation number 2 to 9 incorporating a metal at its terminal end, branching points or both. In particular, such polyester-polyol exhibits microbial inhibiting properties to Candida albicans, Staphylococcus auerus, Escherichia coli and Pseudomonas aeruginosa.

BACKGROUND OF THE INVENTION

Hyperbranched polymers are highly branched macromolecules with three- dimensional dentritic architecture. They are usually prepared by one-pot synthesis which limits the control on molar mass and branching accuracy therefore leads to less consistency in distribution of molar mass and branching. This distinguishes hyperbranched polymers from perfectly branched and monodisperse dendrimers. Due to their highly branched and dense but irregular structure, they exhibit excellent solubility, low solution viscosity, modified melt rheology and high level of terminal end group functionality. Due to their unique characteristics, there exists applications from drug delivery to coating formulation. This patent document focuses on hyperbranched polymer with microbial inhibiting properties.

Patent Cooperation Treaty Patent Publication no. WO 2001012725 Al disclosed a curable antimicrobial hyperbranched polymer composition. In particular, the antimicrobial compound is a polyhexamethylene biguanide derivative, a chlorhexidine derivative, a quarternary ammonium salt, a phenolic compound and preferably 2,4,4'-trichloro-2'-hydroxy-diphenylether. Another Patent Cooperation Treaty Patent Publication no. WO 2009099055 Al disclosed an antibacterial hyperbranched polymer containing a cationic functional group, preferably derived from quaternary ammonium salt. These cationic functional groups may be responsible in damaging cell walls or membranes of a bacteria. As an alternative, this invention provides a hyperbranched polymers incorporating a metal so as to impart microbial inhibiting properties therein.

SUMMARY OF THE INVENTION

The present invention provides a hyperbranched polymer derived from environmental friendly source. Particularly, the polymer is polyester-polyol derived based on solvent-free polycondensation between a polyol and a dicarboxylic acid derived from palm oil derivatives. The present invention provides a microbial inhibiting hyperbranched polymer and composition thereof, both of which could inhibiting growth of Candida albicans, Staphylococcus auerus, Escherichia coli and Pseudomonas aeruginosa.

In the preferred embodiment, the present invention is a hyperbranched polyester- polyol of generation 5 to 9 incorporating a metal selected from the group consisting of cobalt, nickel, copper, zinc, tin, cadmium, iron, manganese, chromium or a combination of two or more thereof in an amount of 0.1 to 20% by weight of the polyester-polyol. Preferably, the polyester-polyol has a degree of branching of 5 to 90%.

Preferably, the polyester-polyol is a polycondensation product of a polyol having 2 to 6 hydroxyl functional groups and a dicarboxylic acid having 4 to 12 carbon atoms. Preferably, the polyol has 3 to 6 carbon atoms. Advantageously, the polyol is glycerol, trimethylolpropene or pentaerythritol.

Preferably, the dicarboxylic acid is saturated linear dicarboxylic acid selected from butanedioic acid, pentadioic acid, hexadioic acid, heptanedioic acid, octanedioic acid, nonanedioic acid and decanedioic acid. Preferably, the dicarboxylic acid is unsaturated dicarboxylic acids selected from maleic acid, fumaric acid, glutaconic acid, muconic acid, traumatic acid and mesaconic acid.

Preferably, the dicarboxylic acid is substituted dicarboxylic acid selected from tartonic acid, tartaric acid, mesoxalic acid and acetonedicarboxylic acid.

Preferably, the dicarboxylic acid is phthalic acid.

Preferably, the mole ratio of the polyol and the dicarboxylic acid used is 1 to 3.5: 0.1 to 1.

Preferably, the metal used is derived acetate, hydroxide, chloride, sulfate or nitrate of the metal.

Preferably, the hyperbranched polyester-polyol incorporates atoms of the metal at its terminal end, branching point or both. Further, this invention provides a composition for inhibiting growth of Candida albicans, Staphylococcus auerus, Escherichia coli and Pseudomonas aeruginosa, in which the composition comprises a hyperbranched polyester-polyol of generation 5 to 9 incorporating a metal selected from the group consisting of cobalt, nickel, copper, zinc, cadmium, iron, manganese, chromium or a combination of two or more thereof in an amount of 0.1 to 20 % by weight of the polyester-polyol.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a C-13 NMR spectrum of a metal-incorporated hyperbranched polyester-polyol of one preferred embodiment of the invention. Figure 2 is a C-13 NMR spectrum of the hyperbranched polyester-polyol of Figure 1 after incorporating metal. DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a hyperbranched polyester-polyol incorporating metal so as to impart microbial inhibiting properties therein.

By way of examples, embodiments of the invention will now be described in detailed. However, it is to be understood that limiting the description to the preferred embodiments of the invention and to the drawings is merely to facilitate discussion of the present invention and it is envisioned that those skilled in the art may devise various modifications without departing from the scope of the appended claim. In one of the preferred embodiment, a hyperbranched polyester-polyol is first prepared according to A ₂ + B ₃ approach whereby direct polycondensation preferably occurs between 2 moles of glycerol (B ₃ ) to 1 mole of adipic acid (A ₂ ). It shall be noted that there is no solvent involved in the polycondensation. Hence, 40 g of adipic acid is first heated to its molten form above its melting point, preferably above 110 °C yet below the boiling point of glycerol (approximately 290 °C). Thereinafter, 50.4 mL of glycerol is added drop wise into the molten adipic acid. It is contemplated that the mole ratio of the glycerol and adipic acid, reaction temperature and duration determines the number of generations capable to be achieved. More particularly, the number of generations substantially influences viscosity of the hyperbranched polyester-polyol. It is preferred that this step is conducted under pressure of 50 mbar or purging of nitrogen gas to remove water by-product. According to the preceding description, the hyperbranched polyester-polyol of generation number 2-5 having weight average molecular weight between 700 to 2000 g/mol and viscosity of 2000 to 15000 cPa at room temperature is formed. Particularly, the hyperbranched polyester- polyol has a degree of branching between 70 to 79%. At this point, the hyperbranched polyester-polyol has an acid value of 10 to 70 mg KOH g sample. According to Figure 1, hyperbranched polyester-polyol is formed. Further, the resulted hyperbranched polyester-polyol is characterized in Table 1 in terms of polydispersity index and weight-average molecular weight.

Table 1: Gel permeation chromatography results for polyester polyol reacted at 180 °C withdrawn at different reaction time.

Thereinafter, 0.75-6.0 g of cobalt (II) hydroxide is added into the hyperbranched polyester-polyol. Due to good solubility of the hyperbranched polyester-polyol, the cobalt (II) hydroxide is dissolved therein, optionally in the presence of stirring and heat. It is preferred that this step is conducted under pressure of 50 mbar or purging of nitrogen gas to remove by-products for approximately 1 to 10 hours at temperature of 150 to 230 °C. Cobalt bond covalently to carboxylic, ester or both groups of the hyperbranched polyester-polyol. Hence, cobalt is incorporated into the structure of the hyperbranched polyester-polyol at terminal ends, branching points or both. Accordingly, a cobalt-incorporated hyperbranched polyester-polyol of the same generation having the weight average molecular weight between 3000 to 32000 g/mol and viscosity of 5000 to 25000 cPa at room temperature is formed. At this point, the cobalt-incorporated hyperbranched polyester-polyol has an acid value of 1 to 15 mg KOH/g sample. According to Figure 2, cobalt-incorporated hyperbranched polyester- polyol is formed. Further, the resulted cobalt-incorporated hyperbranched polyester- polyol is characterized in Table 2 in terms of polydispersity index and weight-average molecular weight.

Table 2: Gel permeation chromatography results for cobalt-incorporating hyperbranched polyester-polyol after 1 hour of cobalt incorporation.

A coating composition for inhibiting growth of Candida albicans, Staphylococcus auerus, Escherichia coli and Pseudomonas aeruginosa on substrate such as wood, glass, paper, ceramic, metal or polymer can be formed based on the cobalt- incorporated hyperbranched polyester-polyol as set forth in preceding description. In the preferred embodiment, the cobalt-incorporated hyperbranched polyester-polyol is present in an amount of 5% by weight of the coating composition. The coating composition can be blends of alkyd, paint, resin, varnish or any polymer coating to form an antimicrobial protective coating.