Coating apparatus and coating method
The mounting is formed by grinding an integrally molded material with accuracy of the μm order. An upper portion of the mounting is an L-shaped holding portion on which a slot die is positioned. An upper face of the holding portion contacts a lower face of the slot die, and a side face of the holding portion contacts a rear face of the slot die. The lower and rear faces of the slot die and the upper and side faces of the holding portion are formed to have such a straightness for the total length that the unevenness thereof may be in 5 μm. Thus the slot die can be held with high accuracy, and the clearance accuracy between the lips and a web can be increased.
1. A coating apparatus for coating a web with a coating solution to form a coating layer, comprising:
a mounting obtained by grinding an integrally molded material; and
a die supported by said mounting, said coating solution being discharged between lips of said die,
wherein one of said lips is disposed on the downstream side of a transporting direction of said web from another one of said lips and formed to have such a straightness for its total length that unevenness of a surface of said one lip on the downstream side is at most 5 μm in a widthwise direction of the coating, and each contact face of said mounting to said die and that of said die to said mounting are formed to have such a straightness for its total length that said unevenness of each face is at most 5 μm in a widthwise direction of the coating.
2. A coating apparatus as defined in claim 1 , wherein said mounting is formed of stainless.
3. A coating apparatus as defined in claim 1 , wherein said one lip disposed on said downstream side is formed from a hard alloy material in which carbide crystals having average diameter of 5 μm are bound, and said hard alloy material is different from a material for a main body of said die to which said lips are attached.
4. A coating apparatus as defined in claim 3 , wherein a coefficient of linear thermal expansion of said materials for said main body of said die is smaller than a coefficient of linear thermal expansion of said materials for forming said one lip on said downstream side of said transporting direction.
5. A coating apparatus as defined in claim 1 , wherein said mounting includes heat-retention holes for circuitously feeding hot water such that the temperature of said mounting before the coating may be almost equal to that during the coating.
6. A coating apparatus as defined in claim 1 , wherein said die is formed from material whose coefficient of linear thermal expansion is at most 1.1×10 −5 [1/K].
7. A coating apparatus as defined in claim 6 , wherein said die is formed from material whose coefficient of linear thermal expansion is at most 6.0×10 −6 [1/K].
8. A coating apparatus as defined in claim 1 , wherein said mounting and said die are fastened with bolts, and said bolts are disposed in 100 mm from an edge of a widthwise direction of said die.
9. A coating apparatus as defined in claim 8 , wherein said die includes at least two contact faces which are fastened to said mounting with said bolts.
10. A coating apparatus as defined in claim 1 , wherein a clearance between said lips and said web is at most 100 μm.
11. A coating apparatus as defined in claim 1 , wherein wet film thickness of said coating layer is at most 20 μm.