Heat-shrinkable laminated film, molded product and heat-shrinkable label comprising the film, and container
A heat-shrinkable laminated film having: (A) layer mainly having a polyester series resin; (C) layer mainly having a polystyrene series resin or mixture of polyester series and polystyrene series resins; and (B) layer mainly having polyester series and polystyrene series resins and disposed between (A) and (C) layers, the film having excellent heat-shrinkability, transparency, and interlayer-adhesiveness at room temperature, not easily peeled in a high-temperature treatment, inhibited from whitening when bent during processing, and suitable for shrinkage-packaging, shrink-bond-packaging, etc., with (B) layer having: a hard polyester series resin or mixture of hard polyester series and soft polyester series resins; and soft styrene series resin, hard styrene series resin, or mixture thereof, or with a content of the (B) layer polyester series resin smaller than that of the (A) layer one, and a content of the (C) layer polyester series resin smaller than that of the (B) layer one.
1. A heat-shrinkable laminated film, comprising:
a first A layer;
a first B layer placed on the first A layer;
a C layer placed on the first B layer;
a second B layer placed on the C layer; and
a second A layer placed on the second B layer,
wherein
the first and second A layers have a resin composition comprising a polyester resin as a main component,
the first and second B layers have a resin composition comprising a combination of a polyester resin and a polystyrene resin as a main component, where the polyester resin in the first and second B layers is a hard polyester resin or a mixture of a hard polyester resin and a soft polyester resin, the polyester resin in the first and second B layers is different from the polyester resin in the first and second A layers, and the polystyrene resin in the first and second B layers is a soft polystyrene resin, a hard polystyrene resin, or a mixture thereof,
the hard polyester resin has a storage elastic modulus (E′) of 3.00×10 8 Pa or more, the soft polyester resin has an E′ value of less than 3.00×10 8 Pa, the hard polystyrene resin has an E′ value of 4.00×10 8 Pa or more, and the soft polystyrene resin has an E′ value of less than 4.00×10 8 Pa, under conditions of an oscillation frequency of 10 Hz, a distortion of 0.1%, and a temperature of 30° C.,
the C layer comprises a resin composition comprising a polystyrene resin as a main component,
a mass ratio of the polyester resin in the first and second B layers to the polystyrene resin in the first and second B layers is from 90/10 to 30/70, and
when the heat-shrinkable laminated film is cut to obtain a rectangle film piece having a size of 110 mm in a drawing direction MD and 235 mm in a direction TD orthogonal to the drawing direction MD, the rectangle film piece having a first end side and a second end side extending parallel to the drawing direction MD of the rectangle film piece,
a portion of the first A layer on the first end side of the rectangle film piece is placed on a portion of the second A layer on the second end side of the rectangle film piece to form an overlapping portion parallel to the drawing direction MD,
the overlapping portion is sealed by applying a solvent to form a cylindrical film such that the overlapping portion has a width of 2 to 7 mm, and
the cylindrical film is wrapped around a square-shaped polyethylene terephthalate bottle having a capacity of 350 ml, dipped in hot water of 99° C. for 10 seconds, and then returned to room temperature,
a misalignment width between an edge of the first A layer in the first end side and an edge of the C layer in the first end side, or a misalignment width between edges of the first A layer and the first B layer in the first end side and the edge of the C layer in the first end side is not more than 5% of the width of the overlapping portion.
2. The heat-shrinkable laminated film of claim 1 , wherein the polyester resin in the first and second A layers comprises a component derived from terephthalic acid as a dicarboxylic acid component, and a component derived from ethylene glycol and 1,4-cyclohexanedimethanol as a diol component.
3. The heat-shrinkable laminated film of claim 1 , wherein the polystyrene resin in the C layer comprises a copolymer of a styrene hydrocarbon and a conjugated diene hydrocarbon.
4. The heat-shrinkable laminated film of claim 1 , wherein each of the first and second B layers further comprises a compatibilizer that facilitates compatibility between the polyester resin in the first and second A layers or the first and second B layers, and the polystyrene resin in the first and second B layers or the C layer.
5. The heat-shrinkable laminated film of claim 1 , wherein the C layer further comprises a polyester resin and a compatibilizer that facilitates compatibility between the polyester resin in the C layer and the polystyrene resin in the C layer.
6. The heat-shrinkable laminated film of claim 1 , wherein the heat-shrinkable laminated film has a heat shrinkage ratio of 20% or more in at least one direction when dipped in hot water of 80° C. for 10 seconds.
7. A molded product, comprising:
a base material comprising the heat-shrinkable laminated film of claim 1 .
8. A heat-shrinkable label, comprising:
a base material comprising the heat-shrinkable laminated film of claim 1 .
9. A container, comprising:
the molded product of claim 7 .
10. A container, comprising:
the heat-shrinkable label of claim 8 .
11. The heat-shrinkable laminated film of claim 1 , wherein the hard polyester resin in the first and second B layers is at least one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and a polyester formed from terephthalic acid and 1,4-cyclohexanedimethanol; a copolymer thereof; and a copolyester comprising at least one of isophthalic acid, ethylene glycol, polyalkylene glycol, and 1,4-cyclohexanedimethanol as a copolymerization component.
12. The heat-shrinkable laminated film of claim 1 , wherein the hard polyester resin has a storage elastic modulus (E′) of 4.00×10 8 Pa or more under the conditions of an oscillation frequency of 10 Hz, a distortion of 0.1%, and a temperature of 30° C.
13. The heat-shrinkable laminated film of claim 1 , wherein the hard polyester resin has a storage elastic modulus (E′) of 5.00×10 8 Pa or more under the conditions of an oscillation frequency of 10 Hz, a distortion of 0.1%, and a temperature of 30° C.
14. The heat-shrinkable laminated film of claim 1 , wherein a ratio of a thickness of the C layer to a thickness of the first or the second A layer is from 2 to 6.
15. The heat-shrinkable laminated film of claim 1 , wherein a thickness of each of the first and second B layers is from 10 to 100% of a total thickness of the first and second A layers.
16. The heat-shrinkable laminated film of claim 1 ,
wherein a ratio of a thickness of the C layer to a thickness of the first or the second A layer is from 2 to 6, and
a thickness of each of the first and second B layers is from 10 to 100% of a total thickness of the first and second A layers.
17. The heat-shrinkable laminated film of claim 1 , wherein the polyester resin in the first and second B layers consists of the hard polyester resin.
18. The heat-shrinkable laminated film of claim 1 , wherein a mass ratio of the polyester resin to the polystyrene resin in the first and second B layers is from 80/20 to 40/60.
19. The heat-shrinkable laminated film of claim 4 , wherein a mass ratio of the polyester resin to the polystyrene resin in the first and second B layers is from 80/20 to 40/60.
20. The heat-shrinkable laminated film of claim 16 , wherein a mass ratio of the polyester resin to the polystyrene resin in the first and second B layers is from 80/20 to 40/60.