PVOH-based coating solutions

• US 6,444,750 B1
• Filed: 03/06/1995
• Issued: 09/03/2002
• Est. Priority Date: 03/06/1995
• Status: Expired due to Term

• Current Assignee: Jindal FIlms Americas LLC (Jindal Films India Ltd.)
• Original Assignee: Exxonmobil Oil Corporation (Exxon Mobil Corporation)
• Inventors: Touhsaent, Robert E.
• Primary Examiner(s): Reddick, Judy M.
• Application Number:
  US08/399,384
• Time in Patent Office: 2,738 Days
• Field of Search: 525/417, 525/58, 524/503, 427/316, 427/372.2, 427/393.5, 427/536, 427/569, 428/502, 428/515, 428/516, 428/524
• US Class Current: 525/58
• CPC Class Codes: B32B 27/00 Layered products comprising a layer of synthetic resin fibrous or filamentary layer made of a synthetic resin B32B5/02; particulate layer made of a synthetic resin B32B5/16; foamed layer made of a synthetic resin B32B5/18
• CPC Class Codes: C08J 2429/00 Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
• CPC Class Codes: C08J 7/0427 with only one layer of a composition containing a polymer binder with more layers C08J7/042
• CPC Class Codes: C08J 7/043 Improving the adhesiveness of the coatings per se, e.g. forming primers adhesives in the form of films or foils characterised by the primer layers between the polymer carriers and the adhesives C09J7/50
• CPC Class Codes: C08J 7/048 Forming gas barrier coatings
• CPC Class Codes: C08K 5/07 Aldehydes; Ketones
• CPC Class Codes: C08L 2666/28 Non-macromolecular organic substances
• CPC Class Codes: C08L 29/04 Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• CPC Class Codes: C09D 129/04 Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• CPC Class Codes: Y10T 428/31862 Melamine-aldehyde
• CPC Class Codes: Y10T 428/31909 Next to second addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31913 Monoolefin polymer
• CPC Class Codes: Y10T 428/31942 Of aldehyde or ketone condensation product

Abstract

An improved PVOH-based coating solution for application to a polymeric substrate. The coating solution includes poly(vinyl alcohol), a formaldehyde-containing crosslinking agent and a crosslinking-promoting acid catalyst which lowers the pH of the solution to about 3.5 or less and, preferably, to about 3 or less. The coating solution exhibits improved viscosity stability, particularly with the addition of a second acid catalyst. The coating solution also provides improved crosslinking and oxygen barrier characteristics upon drying.

Claims

1. A polymeric film structure having an enhanced oxygen barrier produced by the process comprising:

coating at least one side of a polymeric substrate adapted for receipt of an oxygen barrier with a solution of poly(vinyl alcohol), formaldehyde-containing crosslinking agent and crosslinking-promoting acid catalyst, said solution having a pH of about 3.5 or less, and

wherein said acid catalyst is selected from the group consisting of phosphoric acid nitric acid and hydrochloric acid.

2. The film structure according to claim 1, wherein said solution has a pH of about 3.0 or less.

3. The film structure according to claim 1, wherein said solution includes from about 5 pphr to about 35 pphr by weight of said crosslinking agent.

4. The film structure according to claim 1, wherein said formaldehyde-containing crosslinking agent is melamine formaldehyde.

5. The film structure according to claim 1, wherein said solution further comprises a second acid catalyst.

6. The film structure according to claim 5, wherein said second acid catalyst is an organic acid selected from the group consisting of citric acid, maleic acid and lactic acid.

7. The film structure according to claim 6, wherein said solution includes from about 1 ppHr to about 15 ppHr of said second acid catalyst.

8. The film structure according to claim 1, further comprising a polymeric layer adhered to said oxygen barrier whereby said oxygen barrier is sealed between said polymeric substrate and said polymeric layer.

9. A method of producing a film structure having an enhanced oxygen barrier layer adhered thereto, comprising:

coating at least one side of a polymeric substrate adapted for receipt of an oxygen barrier with a solution of poly (vinyl alcohol), formaldehyde-containing crosslinking agent and crosslinking-promoting acid catalyst, said solution having a pH of about 3.5 or less and

wherein said acid catalyst is selected from the group consisting of phosphoric acid, nitric acid and hydrochloric acid.

10. The method according to claim 9, wherein said solution has a ph of about 3.0 or less.

11. The method according to claim 9, wherein said solution further comprises a second acid catalyst selected from the group consisting of citric acid, maleic acid and lactic acid.