# US 10,766,986 B2 · Acid resistant polyethylene containers

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- Number: US 10,766,986 B2
- Document ID: US10766986B2
- Status: Granted
- Kind: B2
- Application number: 16/052,909
- Filed: 2018-08-02
- Published: 2020-02-06
- Granted: 2020-09-08
- Earliest claimed: 2018-08-02
- Assignees: NOVA Chemicals (International) S.A.
- Applicants: NOVA Chemicals (International) S.A.
- Inventors: Henry Hay; Derek Wasylenko; Tony Tikuisis; Gilbert Arnould
- Web page: https://patentgrep.com/patent/US10766986B2

## CPC

- B29C 41/06: about two or more axes
- C08F 210/02: Ethene
- B29C 41/003: {characterised by the choice of material}
- B29C 41/042: {by rotating a mould around its axis of symmetry (for concrete B28B21/30)}
- B65D 85/84: for corrosive chemicals
- C08K 5/13: Phenols; Phenolates
- C08K 5/1345: {Carboxylic esters of phenolcarboxylic acids}
- C08K 5/17: Amines; Quaternary ammonium compounds
- C08K 5/32: Compounds containing nitrogen bound to oxygen
- C08K 5/3435: Piperidines
- C08K 5/524: Esters of phosphorous acids, e.g. of H3PO3
- C08K 13/00: Use of mixtures of ingredients not covered by one single of the preceding main groups, each of these compounds being essential
- B29K 2023/06: {PE, i.e. polyethylene}
- B29K 2105/0014: {Catalysts}
- B29K 2105/0044: {Stabilisers, e.g. against oxydation, light or heat}
- B29K 2105/0085: {Copolymers}
- B29L 2031/712: {Containers; Packaging elements or accessories, Packages (closures therefor B29L2031/56; ink or toner cartridges B29L2031/7678; squeeze tubes B29L2023/20; suitcases B29L2031/7418)}
- C08K 5/005: {Stabilisers against oxidation, heat, light, ozone}
- C08K 2201/014: Additives containing two or more different additives of the same subgroup in C08K
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- B65D: CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES

## Abstract

Rotomolded polyethylene containers that are used to store sulfuric acid can become discolored on the interior surface which is in contact with the acid. This problem may be mitigated by the use of an additive package that contains two primary antioxidants.

## Claims

### Claim 1

A method for improving the discoloration resistance of a rotational molded polyethylene container that is contacted with concentrated sulfuric acid, said method comprising the steps of
1) providing a stabilized ethylene copolymer composition, wherein said stabilized ethylene copolymer composition contains an additive package comprising
A.1) a hindered phenolic primary antioxidant;
A.2) a hydroxylamine primary antioxidant;
B) a phosphite secondary antioxidant;
C) a hindered amine light stabilizer; and
2) subjecting said stabilized ethylene copolymer composition to rotational molding conditions to produce a rotational molded polyethylene container; and
3) contacting said rotational molded polyethylene container with concentrated sulfuric acid to produce an acid contacted container;
wherein said acid contacted container has improved color in comparison to a control acid contacted container that is prepared using an additive package that does not contain any of said hydroxylamine primary antioxidant.

### Claim 2 (depends on 1)

The method of claim 1 wherein said ethylene copolymer composition has a melt index, I2, of from 1 to 10 grams per 10 minutes.

### Claim 3 (depends on 1)

The method of claim 1 wherein said ethylene copolymer composition has a density of from 0.93 to 0.95 grams per cubic centimeter.

### Claim 4 (depends on 1)

The method of claim 1 wherein said rotational molding conditions included a molding temperature of from 230 to 350° C. and a heated molded time of from 10 to 60 minutes.

### Claim 5 (depends on 1)

The method of claim 1 wherein said ethylene copolymer composition is prepared from a catalyst type chosen from single site catalysts, Ziegler Natta catalysts and combinations thereof.

### Claim 6 (depends on 5)

The method of claim 5 wherein said catalyst type consists essentially of at least one single site catalyst.

### Claim 7 (depends on 1)

The method of claim 1 wherein said additive package consists essentially of
A.1) at least one hindered phenolic primary antioxidant;
A.2) at least one hydroxylamine primary antioxidant;
B) at least one phosphite secondary antioxidant; and
C) at least one hindered amine light stabilizer.

### Claim 8 (depends on 7)

The method of claim 7 wherein said additive package consists essentially of:
A.1) from 300 to 1500 ppm of at least one hindered phenolic primary antioxidant;
A.2) from 100 to 1000 ppm of at least one hydroxylamine primary antioxidant;
B) from 500 to 2000 ppm of at least one phosphite secondary antioxidant; and
C) from 500 to 5000 ppm of at least one hindered amine light stabilizer.