Foamed sheet and method for producting the same
OwnerTakeshi Minaba, Koji Yamatsuta +1inventors
InventorsTakeshi Minaba, Koji Yamatsuta, Yoshinori Ohmura
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Abstract
The present invention provides a foamed sheet showing small dimensional changes resulted with temperature changes, etc., said foamed sheet which made of a thermoplastic resin material, wherein the coefficient of linear expansion of the thermoplastic resin material α (/°C.) and the coefficient of linear expansion of the foamed sheet αf (/°C.) satisfy the following expression (1): |αf/α|≦½ (1) and the like.
Claims3
A foamed sheet made of a thermoplastic resin material, wherein the coefficient of linear expansion of the thermoplastic resin material α (/°C.) and the coefficient of linear expansion of the foamed sheet αf (/°C.) satisfy the following expression (1):
- |αf/α≦½ (1)
A foamed sheet made of a thermoplastic resin material, wherein at least cells present in one pair of cross-sections along thickness directions of the foamed sheet, the cross-sections being perpendicular to each other, satisfy the following expression (2):
- Lmax/Lmin≧4.5 (2)
- wherein Lmax and Lmin represent the maximum value and the minimum value, respectively from a total of the four average values (the average values of the cells for X or Y direction on the A or B cross-section) which are obtained by the following procedures including:
- extracting ten cells at random for each of two cross-sections (A cross-section and B cross-section) of the foamed sheet along thickness directions thereof, the cross-sections being perpendicular to each other,
- measuring, for each of the extracted cells, the size of a cell in a sheet thickness direction (X direction) and that in a direction (Y direction) parallel to the sheet surfaces and
- calculating, for each of the directions (X direction and Y direction) on each of the cross-sections (A cross-section and B cross-section), the average value of the sizes of the cells.
Dependencies are inferred from the claim text.