Rotationally Molded Articles For Food Contact Applications

Patent metadata

Field	Value
Publication number	US-2025066606-A1
Application number	US-202418813218-A
Country	US
Kind code	A1
Filing date	Aug 23, 2024
Priority date	Aug 23, 2023
Publication date	Feb 27, 2025
Grant date	—

Abstract

A polymer composition containing a polyoxymethylene polymer in the form of particles for rotational molding applications is disclosed. The polyoxymethylene polymer is selected to have physical characteristics and is combined with one or more impact modifiers in order to produce hollow vessels and other articles having improved physical properties, such as impact strength resistance. The polymer composition of the present disclosure is particularly formulated so as to be food contact grade compliant.

First claim

What is claimed:

1 . A polymer composition for rotational molding applications comprising:
polymer particles comprising a polyoxymethylene polymer blended with an impact modifier, the impact modifier comprising a thermoplastic elastomer, the polyoxymethylene polymer having a melt flow rate of less than about 5 g/10 min, the polyoxymethylene polymer being present in the polymer composition in an amount of at least about 55% by weight, the impact modifier being present in the polymer composition in an amount of from about 4% by weight to about 27% by weight, and wherein the polymer particles further comprise a nucleant and an antioxidant, the polymer particles having an average particle size of from about 250 microns to about 800 microns.

2 . A polymer composition as defined in claim 1 , wherein the impact modifier meets the requirements of European Food Regulation 10/2011 and FDA Food Regulation FDA 21 CFR 177.2470 Title 21 of the Code of Federal Regulations regarding food contact polymers.

3 . A polymer composition as defined in claim 1 , wherein the polyoxymethylene polymer has a melt flow rate of less than about 4 g/10 min and greater than about 0.5 g/10 min.

4 . A polymer composition as defined in claim 1 , wherein the impact modifier comprises a thermoplastic polyurethane elastomer.

5 . A polymer composition as defined in claim 4 , wherein the thermoplastic polyurethane elastomer has a melt flow rate of greater than about 7 g/10 min and less than about 25 g/10 min when measured at 190° C. and at a load of 2.16 kg and wherein the thermoplastic polyurethane elastomer has a melting temperature of from about 150° C. to about 180° C. and wherein the thermoplastic polyurethane elastomer has a Shore A hardness of greater than about 78 and less than about 95 when measured according to ASTM Test D2240.

6 . A polymer composition as defined in claim 1 , wherein the impact modifier comprises a thermoplastic polyester elastomer.

7 . A polymer composition as defined in claim 6 , wherein the thermoplastic polyester elastomer has a melt flow rate of greater than about 7 g/10 min and less than about 25 g/10 min when measured at 190° C. and at a load of 2.16 kg and wherein the thermoplastic polyester elastomer has a melting temperature of from about 150° C. to about 180° C. and wherein the thermoplastic polyester elastomer has a Shore A hardness of greater than about 78 and less than about 95 when measured according to ASTM Test D2240.

8 . A polymer composition as defined in claim 1 , wherein the impact modifier comprises a thermoplastic polyurethane elastomer, a thermoplastic polyester elastomer, or a combination thereof.

9 . A polymer composition as defined in claim 1 , wherein the nucleant comprises a terpolymer.

10 . A polymer composition as defined in claim 1 , wherein the polymer composition does not contain any ultraviolet light stabilizers.

11 . A polymer composition as defined in claim 1 , wherein the polymer composition further contains an acid scavenger, the acid scavenger comprising a carboxylic acid salt.

12 . A polymer composition as defined in claim 11 , wherein the acid scavenger comprises a calcium citrate, a calcium propionate, or mixtures thereof, the acid scavenger being present in the polymer composition in an amount from about 0.001% by weight to about 1% by weight.

13 . A polymer composition as defined in claim 11 , wherein one or more acid scavengers are present in the polymer composition in an amount less than about 0.08% by weight.

14 . A polymer composition as defined in claim 1 , wherein the polymer composition contains calcium propionate and tricalcium citrate, the calcium propionate being present in relation to the calcium citrate at a weight ratio of from about 4:1 to about 1.2:1.

15 . A polymer composition as defined in claim 1 , wherein the polymer composition is free of guanamine, urea, or melamine formaldehyde scavengers.

16 . A polymer composition as defined in claim 1 , wherein the polymer composition further contains a plasticizer and wherein the plasticizer comprises a polyethylene glycol, the polyethylene glycol being present in the polymer composition in an amount from about 0.01% by weight to about 2% by weight, such as from about 0.1% by weight to about 0.8% by weight.

17 . A polymer composition as defined in claim 1 , wherein the polymer composition does not contain a polyethylene glycol.

18 . A polymer composition as defined in claim 1 , wherein the polymer composition contains at least one coloring agent comprising a yellow coloring agent, a blue coloring agent, a red coloring agent, an orange coloring agent, a green coloring agent, a white coloring agent, a black coloring agent, or mixtures thereof.

19 . A polymer composition for rotational molding applications comprising:
polymer particles comprising a polyoxymethylene polymer blended with an impact modifier, the impact modifier comprising a thermoplastic elastomer, the polyoxymethylene polymer having a melt flow rate of less than about 10 g/10 min, the polyoxymethylene polymer being present in the polymer composition in an amount of at least about 55% by weight, the impact modifier being present in the polymer composition in an amount from about 4% by weight to about 27% by weight, the polymer particles having an average particle size of from about 250 microns to about 800 microns, the polymer composition further containing a masterbatch comprising a coloring agent in combination with a carrier polymer, the coloring agent being present in the polymer composition in an amount less than about 1% by weight, the polymer composition displaying a Delta E color shift according to SAE Test J2527 at 500 kJ/m 2 of less than about 10.

20 . A polymer composition as defined in claim 19 , wherein the polymer composition displays a Delta E color shift of less than about 5 and wherein the coloring agent comprises carbon black or graphite and wherein the carrier polymer comprises a polyethylene polymer or a polyoxymethylene polymer and is present in the masterbatch in an amount from about 50% by weight to about 99% by weight.

21 . A food contact article comprising:
a seamless rotationally molded food container defining an interior space for contacting food stuffs, the food container comprising a wall made from the polymer composition as defined in claim 1 .

22 . A food contact article as defined in claim 21 , wherein the wall has a thickness of from about 0.5 mm to about 10 mm and wherein the food container has an interior volume of greater than about 3 gallons and less than about 800 gallons and wherein the wall of the food container has a density according to ISO Test 1183 of greater than 1.1 g/cc and less than about 1.6 g/cc.

Assignees

• Celanese Int Corp

Inventors

• Grinsteinner Darin
• Larkin Adam

Classifications

• C08L67/025

  containing polyether sequences · CPC title

• C08L59/02

  Polyacetals containing polyoxymethylene sequences only · CPC title

• C08L71/02 Primary

  Polyalkylene oxides · CPC title

• B65D2519/00666

  Structures not intended to be disassembled · CPC title

• B65D2519/00621

  sidewalls directly connected to each other · CPC title