Drawn/ironed can and coated metal sheet for drawn/ironed cans
AssigneeToyo Seikan Group Holdings, Ltd.
InventorsHiromi Yamamoto, Takuya Kashiwakura, Arata Sakuragi, Nan Zhang
Life of this patent
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Abstract
The disclosure relates to a drawn/ironed can having at least an inner surface coating film on a can inner surface side, the inner surface coating film containing a polyester resin and a curing agent, and a stress relaxation ratio of the inner surface coating film after 10 minutes at 1% elongation in a can bottom portion is 50% or higher under a test condition of 100° C., whereby metal exposure due to severe processing such as drawing or ironing and coating film peeling due to heat treatment after molding are effectively prevented.
Claims17
A drawn/ironed can comprising at least an inner surface coating film on a can inner surface side, the inner surface coating film comprising a polyester resin and a curing agent, wherein a stress relaxation ratio of the inner surface coating film after 10 minutes at 1% elongation in a can bottom portion is 50% or higher;
- wherein, when a total amount of polyhydric alcohol components constituting the polyester resin is 100 mol %, the polyester resin contained in the inner surface coating film comprises one, or two or more selected from ethylene glycol, propylene glycol, 1,4-butanediol, 2-methyl-1,3-propanediol, and diethylene glycol in an amount of 20 mol % or greater in total,
- wherein the stress relaxation ratio is measured as follows:
- a sample for measurement is prepared by removing the inner surface coating film from the can bottom portion and then cutting the inner surface coating film into 40 mm long with 4 mm wide to obtain the sample,
- using a thermomechanical analyzer for the sample, after the sample was chucked with no deflection in the thermomechanical analyzer, an inter-chuck distance corresponding to the initial length of the sample was set to 10 mm;
- then, a measurement atmosphere temperature was raised, and 10 minutes after 100° C. was reached, the sample was elongated by 1% of the initial length of the sample at a tensile rate of 1 mm/min, and held in the state for 10 minutes;
- and then the stress relaxation ratio was calculated from a stress (Δ1) at 1% elongation and a stress (Δ2) after the 10-minute holding by the following formula (1) under the following Measurement conditions:
- Instrument:
- thermomechanical analyzer TMA/SS6100, available from Seiko Instruments Inc.
- Measurement atmosphere temperature:
- 100° C.
- Inter-chuck distance:
- 10 mm
- Tensile rate:
- 1 mm/min
- Elongation rate (tensile elongation strain):
- 1%
- Stress relaxation ratio (%)=(Δ1−Δ2)/Δ1×100 (1),
- wherein, in formula (1), Δ1 is a stress at 1% elongation, and →2 is a stress after 10-minute holding, and a numerical value of each of Δ1 and Δ2 is a correction value obtained by subtracting a numerical value of a stress immediately before 1% elongation after reaching 100° C. from an actual measurement value.
A coated metal sheet for a drawn/ironed can comprising a coating film on both surfaces, wherein an inner surface coating film of a surface to be on a can inner surface side after drawing and ironing contains a polyester resin and a resol phenolic resin and/or an amino resin as a curing agent, an outer surface coating film of a surface to be on a can outer surface side after drawing and ironing contains a polyester resin and an amino resin as the curing agent, and wherein a stress relaxation ratio of the inner surface coating film after 10 minutes at 1% elongation is 50% or higher, and a stress relaxation ratio of the outer surface coating film after 10 minutes at 1% elongation is higher than 40% under a test condition of 100° C.;
- wherein when a total amount of polyhydric alcohol components constituting the polyester resin is 100 mol %, the polyester resin contained in the inner surface coating film contains one, or two or more selected from ethylene glycol, propylene glycol, 1,4-butanediol, 2-methyl-1,3-propanediol, and diethylene glycol in an amount of 20 mol % or greater in total,
- wherein the stress relaxation ratio is measured as follows:
- a sample for measurement is prepared by removing the inner surface coating film from the can bottom portion and then cutting the inner surface coating film into 40 mm long with 4 mm wide to obtain the sample,
- using a thermomechanical analyzer for the sample, after the sample was chucked with no deflection in the thermomechanical analyzer, an inter-chuck distance corresponding to the initial length of the sample was set to 10 mm;
- then, a measurement atmosphere temperature was raised, and 10 minutes after 100° C. was reached, the sample was elongated by 1% of the initial length of the sample at a tensile rate of 1 mm/min, and held in the state for 10 minutes;
- and then the stress relaxation ratio was calculated from a stress (Δ1) at 1% elongation and a stress (Δ2) after the 10-minute holding by the following formula (1) under the following Measurement conditions:
- Instrument:
- thermomechanical analyzer TMA/SS6100, available from Seiko Instruments Inc.
- Measurement atmosphere temperature:
- 100° C.
- Inter-chuck distance:
- 10 mm
- Tensile rate:
- 1 mm/min
- Elongation rate (tensile elongation strain):
- 1%
- Stress relaxation ratio (%)=(Δ1−Δ2)/Δ1×100 (1),
- wherein, in formula (1), Δ1 is a stress at 1% elongation, and Δ2 is a stress after 10-minute holding, and a numerical value of each of Δ1 and Δ2 is a correction value obtained by subtracting a numerical value of a stress immediately before 1% elongation after reaching 100° C. from an actual measurement value.
Dependencies are inferred from the claim text.