Heat-shrinking multilayer film and heat-shrinking label

Patent metadata

Field	Value
Publication number	US-11453209-B2
Application number	US-201916982402-A
Country	US
Kind code	B2
Filing date	Jun 26, 2019
Priority date	Jul 25, 2018
Publication date	Sep 27, 2022
Grant date	Sep 27, 2022

Abstract

The present invention provides a heat shrinkable multilayer film that can prevent layer misalignment at a center seal portion and thereby provide a labelled container having excellent appearance when the film is attached to a container as a heat shrinkable label for dry heat shrinking, and a heat shrinkable label including the heat shrinkable multilayer film as a base film. Provided is a heat shrinkable multilayer film including: front and back layers each containing a polyester resin; an interlayer containing a polystyrene resin; and adhesive layers, wherein the front and back layers and the interlayer are stacked with the adhesive layers interposed therebetween, and the heat shrinkable multilayer film has a maximum shrinkage stress of 3.5 to 11 MPa when immersed in hot water at 80° C. for 30 seconds.

First claim

The invention claimed is:

1. A heat shrinkable multilayer film comprising:
front and back layers each containing a polyester resin;
an interlayer containing a polystyrene resin; and
adhesive layers each containing a styrene-butadiene copolymer, which is a copolymer consisting of a component derived from styrene as an aromatic vinyl hydrocarbon and a component derived from 1,3-butadiene as a conjugated diene,
wherein the front and back layers and the interlayer are stacked with the adhesive layers interposed therebetween,
the heat shrinkable multilayer film has a maximum shrinkage stress of 3.5 to 11 MPa, which is measured by immersing in hot water at 80° C. for 30 seconds,
the polystyrene resin constituting the interlayer is a mixed resin containing a styrene-butadiene copolymer (A) having a Vicat softening temperature of 80° C. or higher and a styrene-butadiene copolymer (B) having a Vicat softening temperature of lower than 80° C.,
the interlayer contains 1 to 35% by weight of the styrene-butadiene copolymer (A) and 65 to 99% by weight of the styrene-butadiene copolymer (B),
wherein the styrene-butadiene copolymer (A) and the styrene-butadiene copolymer (B) in the interlayer represents all of the polystyrene resin in the interlayer, and

the styrene-butadiene copolymer constituting the adhesive layers has a higher butadiene content than all of the styrene-butadiene copolymers constituting the interlayer.

2. The heat shrinkable multilayer film according to claim 1 ,
wherein the polyester resin constituting the front and back layers has a glass transition temperature of 55° C. to 95° C.

3. The heat shrinkable multilayer film according to claim 1 ,
wherein the adhesive layer contains the styrene-butadiene copolymer in an amount of 35 to 70% by weight and a polyester elastomer in an amount of 30 to 65% by weight.

4. A heat shrinkable label comprising
the heat shrinkable multilayer film according to claim 1 .

Assignees

• Gunze Kk

Inventors

• Nozaki Takanori

Classifications

• B32B2519/00

  Labels, badges · CPC title

• B32B2307/736

  Shrinkable · CPC title

• G09F3/04

  to be fastened or secured by the material of the label itself, e.g. by thermo-adhesion (by a separate adhesive layer G09F3/10) · CPC title

• G09F2003/0272

  Labels for containers · CPC title

• G09F3/0291

  Labels or tickets undergoing a change under particular conditions, e.g. heat, radiation, passage of time · CPC title