Molding base paper and molded paper vessel produced from it

• US 20040191437A1
• Filed: 04/05/2004
• Published: 09/30/2004
• Est. Priority Date: 05/31/2000
• Status: Abandoned Application

• Current Assignee: OJI Paper Company Limited (Oji Holdings Corporation)
• Original Assignee: OJI Paper Company Limited (Oji Holdings Corporation)
• Inventors: Mikado, Hideyuki, Asayama, Yoshiyuki
• Application Number:
  US10/816,848
• Publication Number:
  US 20040191437A1
• Time in Patent Office: Days
• US Class Current: 428/34.2
• CPC Class Codes: B31F 1/0077 Shaping by methods analogous to moulding, e.g. deep drawing techniques
• CPC Class Codes: D21H 11/02 Chemical or chemomechanical or chemothermomechanical pulp
• CPC Class Codes: D21H 11/08 Mechanical or thermomechanical pulp
• CPC Class Codes: D21H 19/00 Coated paper coated fibreboard D21J1/08; Coating material recording sheets characterised by the coating used to improve ink, dye or pigment receptivity B41M5/50
• CPC Class Codes: D21H 27/38 at least one of the sheets having a fibrous composition differing from that of other sheets
• CPC Class Codes: Y10T 428/1303 Paper containing [e.g., paperboard, cardboard, fiberboard, etc.]

Abstract

A molding base paper used for forming paper vessels such as a cup or tray for foods and various industrial products is disclosed which satisfies the following conditions (1) to (4):

(1) a tensile strength (JIS-P 8113) of at least 2.0 kN/m,

(2) an elongation at break (JIS-P 8113) of at least 1.5 %,

(3) a critical compression stress, defined by the following formula, in the range of 1 to 10 MPa:

critical compression stress =A/B

wherein A represents the compression strength determined by JIS-P 8126, and B represents the area of loaded part of the test piece in the determination of the compression strength, and

(4) an amount of the compression deformation, caused by applying compression stress of 20 kgf/cm²in thickness direction, of at least 10%.

The paper vessels are prepared by controlling the water content of the molding base paper at 10 to 20% and then drawing the molding base paper at 100 to 150° C.

Claims

17. A process for preparing a molded paper vessel, comprising draw-molding under heat and pressure, a molding base paper having the following conditions (1) to (4):

(1) a tensile strength (JIS-P

     8113) of at least 2.0 kN/m,

(2) an elongation at break (JIS-P

     8113) of at least 1.5%,

(3) a critical compression stress, defined by the following formula, in the range of 1 to 10 MPa;

Critical compression stress =A/B

 

wherein A represents the compression strength determined by JIS-P 8126, and B represents the area of loaded part of the test piece in the determination of the compression strength, and

(4) an amount of compression deformation, caused by applying compression stress of 20 kgf/cm² in thickness direction, of at least 10%, so as to form a vessel which satisfies the following formula (5);

0.15≦

H/(S1)^1/2 

 

(5)

 

wherein S1 represents the bottom area of the vessel and H represents the height thereof.

18. The process according to claim 17, wherein said molding base paper comprises a mechanical pulp selected from the group consisting of ground wood pulp, refiner ground wood pulp and thermomechanical pulp.

19. The process according to claim 18, wherein said molding base paper comprises a mechanical pulp in an amount of 20 to 80%.

20. The process according to claim 17, wherein said molding base paper further comprises a synthetic resin layer on at least one surface thereof.

21. A process for preparing a molded paper vessel, comprising draw-molding a molding base paper under heat and pressure, so as to form a molded paper vessel which satisfies the following formula (1):

0.15≦

N/(S1)^1/2 

 

(1)

wherein S1 represents the bottom area of the vessel and H represents the height thereof,

said molding base paper comprising a high density layer having a density of 0.7 to 0.9 g/cm³ and a low density layer having a density of lower than 0.7 g/cm³, and said molding base paper having a basis weight of 100 to 500 g/cm² and a density of 0.40 to 0.70 g/cm³.

22. The process of claim 21, wherein said low density paper is mainly comprised of mechanical pulp.

23. The process of claim 22, wherein said mechanical pulp is thermomechanical pulp.

24. The process according to claim 21, wherein said molding base paper further comprises a synthetic resin layer on at least one surface thereof.