Paper having a melt-stable lactide polymer coating and process for manufacture thereof

• US 5,665,474 A
• Filed: 08/31/1995
• Issued: 09/09/1997
• Est. Priority Date: 10/02/1992
• Status: Expired due to Term

• Current Assignee: Cargill, Inc. (Agricultural Services Division)
• Original Assignee: Cargill, Inc. (Agricultural Services Division)
• Inventors: Ryan, Christopher M., Kolstad, Jeffrey John, Hall, Eric Stanley, Gruber, Patrick Richard, Eichen Conn, Robin Sue
• Primary Examiner(s): Dodson, Shelley A.
• Application Number:
  US08/521,923
• Time in Patent Office: 740 Days
• Field of Search: 427/391, 428/480, 428/481, 428/490, 428/537.5, 525/413, 525/415, 528/354, 528/361
• US Class Current: 428/481
• CPC Class Codes: A61L 15/26 Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof A61L15/225 takes precedence
• CPC Class Codes: A61L 31/06 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds A61L31/041 takes precedence
• CPC Class Codes: C08G 2230/00 Compositions for preparing biodegradable polymers
• CPC Class Codes: C08G 63/08 Lactones or lactides
• CPC Class Codes: C08G 63/90 Purification; Drying
• CPC Class Codes: C08J 2367/04 Polyesters derived from hydroxy carboxylic acids, e.g. lactones C08J2367/06 takes precedence
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 67/04 Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence
• CPC Class Codes: C09D 167/04 Polyesters derived from hydroxycarboxylic acids, e.g. lactones C09D167/06 takes precedence
• CPC Class Codes: D01F 6/625 derived from hydroxy-carboxylic acids, e.g. lactones
• CPC Class Codes: D04H 1/42 characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
• CPC Class Codes: D21H 19/28 Polyesters
• CPC Class Codes: D21H 19/62 Macromolecular organic compounds or oligomers thereof obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: Y02W 30/64 Paper recycling
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]
• CPC Class Codes: Y10T 428/3179 Next to cellulosic
• CPC Class Codes: Y10T 428/31808 Cellulosic is paper
• CPC Class Codes: Y10T 428/31819 Next to cellulosic
• CPC Class Codes: Y10T 428/31993 Of paper

Abstract

A lactide polymer coating resulting in a strong, repulpable, high gloss, paper coating. The lactide polymer comprises a plurality of poly(lactide) polymer chains, residual lactide in concentration of less than about 5 percent and water in concentration of less than about 2000 parts-per-million. A process for coating paper with the lactide polymer composition is also disclosed.

Claims

1. A coated paper product comprising:

(a) a paper substrate having a first surface; and

(b) a polymer coating on said paper substrate first surface;

said polymer coating comprising a melt stable polymer composition formed from at least;

meso-lactide;

lactide reactant; and

, epoxidized oil;

(i) said polymer composition having a number average molecular weight of from about 10,000 to about 200,000;

(ii) said polymer composition having a lactide monomer concentration of less than about 5% by weight; and

(iii) said lactide reactant being selected from the group consisting of L-lactide, D-lactide and mixtures thereof;

(c) said polymer composition being formed from a reaction mixture comprising about 3% to about 50% by weight meso-lactide, based on the total weight of meso-lactide and lactide reactant in the reaction mixture; and

(d) said polymer composition being a polymeric material in a form such that, when isolated and devolatilized, and before incorporation into said polymer coating, it will form less than 1% by weight lactide, upon heating at 180°

C. for 1 hour.

2. A coated paper product according to claim 1 wherein:

(a) said polymer coating comprises a polymer composition having a number average molecular weight of from about 40,000 to about 150,000.

3. A coated paper product according to claim 1 wherein:

(a) said polymer composition is formed from a reaction mixture including an active hydrogen-bearing compound.

4. A coated paper product according to claim 3 wherein:

(a) said polymer composition is formed from a reaction mixture including an active hydrogen-bearing compound wherein the active hydrogen-bearing compound is selected from the group consisting of amines, glycols, diols and triols.

5. A coated paper product according to claim 1 wherein:

(a) said paper substrate is selected from the group consisting of cellulose, lignin, hemicellulose, synthetic fibers and mixtures thereof.

6. A coated paper product according to claim 1 wherein:

(a) said polymer composition is formed from at least;

meso-lactide;

lactide reactant;

epoxidized oil; and

, inorganic filler.

7. A coated paper product according to claim 1 wherein:

(a) said polymer composition is formed from at least;

meso-lactide;

lactide reactant;

epoxidized oil; and

, organic filler.

8. A coated paper product according to claim 1 wherein:

(a) said polymer composition is formed from at least;

meso-lactide;

lactide reactant;

epoxidized oil; and

, an effective amount of antioxidant.

9. A coated paper product according to claim 1 wherein:

(a) said polymer composition is formed from at least;

meso-lactide;

lactide reactant;

epoxidized oil; and

, an effective amount of catalyst deactivating agent.

10. A coated paper product according to claim 1 wherein:

(a) said polymer coating comprises a polymer composition formed from a reaction mixture comprising at least about 7% by weight meso-lactide, based on the total weight of meso-lactide and lactide reactant in the reaction mixture.

11. A coated paper product according to claim 1 wherein:

(a) said paper substrate first surface, with said polymer coating thereon, has a surface energy of at least 35 dynes/cm.

12. A coated paper product according to claim 1 wherein:

(a) said polymer coating includes antistatic agent therein.

13. A coated paper product according to claim 1 wherein:

(a) said polymer coating includes a slip agent therein.

14. A coated paper product according to claim 1 wherein:

(a) said polymer coating includes pigment therein.

15. A coated paper product according to claim 6 wherein:

(a) said filler is compounded into said polymer composition.

16. A coated paper product comprising:

(a) a paper substrate having a first surface; and

(b) a biodegradable polymer coating on said paper substrate first surface;

said biodegradable polymer coating comprising a polymer composition comprising the polymer forming reaction product of at least;

meso-lactide and L-lactide;

(i) said polymer composition having a number average molecular weight of 10,000 to 200,000;

(ii) said polymer composition having a lactide monomer concentration of less than about 5% by weight; and

,

(iii) said polymer composition being formed from a reaction mixture comprising about 3% to about 50% by weight meso-lactide, based on the total weight of meso-lactide, L-lactide and, if present, D-lactide.

17. A coated paper product according to claim 16 wherein:

(a) said polymer composition comprises the polymer-forming reaction product of at least;

meso-lactide;

L-lactide; and

D-lactide.

18. A coated paper product according to claim 16 wherein:

(a) said polymer composition comprises polymer chains including monomer units derived from;

meso-lactide;

L-lactide and at least one other monomer.

19. A coated paper product according to claim 18 wherein:

(a) said at least one other monomer includes D-lactide.

20. A coated paper product according to claim 16 wherein:

(a) said polymer composition comprises the polymer forming reaction product of;

meso-lactide, L-lactide and at least one component capable of reacting into the polymer which is not one of meso-lactide, L-lactide and D-lactide.

21. A coated paper product according to claim 20 wherein:

(a) said at least one component capable of reacting into the polymer which is not one of meso-lactide, L-lactide and D-lactide is material comprising molecules having more than one site for reaction into the polymer.

22. A coated paper product according to claim 20 wherein:

(a) said material comprising molecules having more than one site for reaction into the polymer comprises molecules having at least three sites for reaction into the polymer.

23. A coated paper product according to claim 22 wherein:

(a) said material comprising molecules having at least three sites for reaction into the polymer comprises a triol.

24. A coated paper product according to claim 16 wherein:

(a) said first polymer composition is formed from a mixture including epoxidized oil.

25. A process for preparing coated paper;

said process including the steps of;

(a) melt processing a melt stable polymer composition formed from;

meso-lactide;

lactide reactant; and

epoxidized oil, to form a coating composition;

(i) said polymer composition having a number average molecular weight of 10,000 to 200,000;

(ii) said polymer composition having a lactide monomer concentration of less than about 5% by weight; and

(iii) said lactide reactant being selected from the group consisting of L-lactide, D-lactide and mixtures thereof;

(iv) said polymer composition being formed from a reaction mixture comprising at least 3% by weight meso-lactide, based on the total weight of meso-lactide and lactide reactant; and

(b) applying said coating composition to a paper substrate.

26. A process according to claim 25 including a step of:

(a) calendaring the coated paper.