Patent ID: 11883988
Assignee: KURARAY CO., LTD.
Field: Other special machines (Mechanical engineering)
Classification: CPC B  C  G | IPC B

Claim 1:
2. The polyvinyl alcohol mold release film for artificial marble molding use according to claim 1, wherein the film satisfies the following formulas (2) to (4),

3.0×10−3≥Δn(MD)1−Δn(MD)0≥0.01×10−3  (2)

3.0×10−3≥Δn(MD)2−Δn(MD)0≥0.01×10−3  (3)

1.5×10−3≥|Δn(MD)2−Δn(MD)1|  (4)

in the formulas (2) and (3), Δn(MD)0 has the same meaning as in the formula (1), and in the formulas (2) and (4), Δn(MD)1 represents a value determined from a birefringence index of the polyvinyl alcohol mold release film in the machine direction at one end part of the transverse direction of the film by averaging the birefringence index along the thickness direction of the film, and in the formulas (3) and (4), Δn(MD)2 is a value determined from a birefringence index of the polyvinyl alcohol mold release film in the machine direction at the other end part of the transverse direction of the film by averaging the birefringence index along the thickness direction of the film.