Multilayered tube for draw molding and multilayered container utilizing the tube
AssigneeKuraray Co., Ltd.
InventorsSyuji Kawai, Seio Anzai, Toshinori Ishii, Kenji Shirano, Kunihiko Shimamura, Toshimasa Kanemitsu, Keiji Matsumura
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Abstract
The tube of the present invention has no or very small local minute nonuniformity in thickness of EVOH layer, and therefore drawn-formed articles such as blow bottle obtained by draw molding the tube have no streaks and are superior in appearance.
Claims3
A multilayered tube used for draw molding, which comprises a saturated polyester as the inner and outer layers, a saponified product of ethylene-vinyl acetate copolymer having an ethylene content of 20 to 55 mol% and a saponification degree of vinyl acetate component of at least 96 mol%, and adhesive resin layers interposed between the saturated polyester layers and the saponified product of ethylene-vinyl acetate copolymer layer;
- which satisfies the conditions of the following formulae I- .circle.1 to I- .circle.3 :
- 50.mu..ltoreq.E.ltoreq.1000.mu. I- .circle.1
- 1-0.01H.ltoreq.E/E.ltoreq.1+0.01H I- .circle.2
- E/(A+B).ltoreq.0.2 I- .circle.3
- wherein,
- E:
- wall thickness at any spot of the layer of a saponified product of ethylene-vinyl acetate copolymer (.mu.)
- E:
- average wall thickness of the layer of a saponified product of ethylene-vinyl acetate copolymer (.mu.)
- H:
- average outer diameter of the tube (mm)
- A:
- average wall thickness of the inner layer of the saturated polyester (.mu.)
- B:
- average wall thickness of the outer layer of the saturated polyester (.mu.);
- and in which the layer of a saponified product of ethylene-vinyl acetate copolymer substantially satisfies the following formula II:
- ##EQU9## wherein:
- Emin:
- the minimum wall thickness in .mu. of the layer of a saponified product of ethylene-vinyl acetate copolymer, in the cross section perpendicular to the direction of the tube length, at a point between any point P.sub.n and a point P.sub.n+1 which is distant from P.sub.n by Q=100 to 500.mu. in circumferential distance on the outer surface of the layer,
- Emax:
- the maximum wall thickness in .mu. of the above specified region between P.sub.n and P.sub.n+1.
A method of producing a multilayered container, which comprises preparing a preform from a multilayered tube used for blow molding, which comprises a saturated polyester as the inner and outer layers, a saponified product of ethylene-vinyl acetate copolymer having an ethylene content of 20 to 55 mol% and a saponification degree of vinyl acetate component of at least 96 mol%, and adhesive resin layers interposed between the saturated polyester layers and the saponificated product of ethylene-vinyl acetate copolymer layer;
- which satisfies the conditions of the following formulae I- .circle.1 to I- .circle.3 :
- 50.mu..ltoreq.E.ltoreq.1000.mu. I- .circle.1
- 1-0.01H.ltoreq.E/E.ltoreq.1+0.01H I- .circle.2
- E/(A+B).ltoreq.0.2 I- .circle.3
- wherein,
- E:
- wall thickness at any spot of the layer of a saponified product of ethylene-vinyl acetate copolymer (.mu.)
- E:
- average wall thickness of the layer of a saponified product of ethylene-vinyl acetate copolymer (.mu.)
- H:
- average outer diameter of the tube (mm)
- A:
- average wall thickness of the inner layer of the saturated polyester (.mu.)
- B:
- average wall thickness of the outer layer of the saturated polyester (.mu.);
- and in which the layer of a saponified product of ethylene-vinyl acetate copolymer substantially satisfies the following formula II:
- ##EQU10## wherein:
- Emin:
- the minimum wall thickness in .mu. of the layer of a saponified product of ethylene-vinyl acetate copolymer, in the cross section perpendicular to the direction of the tube length, at a point between any point P.sub.n and a point P.sub.n+1 which is distant from P.sub.n by Q=100 to 500.mu. in circumferential distance on the outer surface of the layer,
- Emax:
- the maximum wall thickness in .mu. of the above specified region between P.sub.n and P.sub.n+1 ;
- and subjecting said preform to biaxial blow molding.
Dependencies are inferred from the claim text.