# US 5,344,715 A · Heat shrinkable film and multilayered film

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- Number: US 5,344,715 A
- Document ID: US5344715A
- Status: Granted
- Kind: A
- Application number: 07/980,761
- Filed: 1992-11-24
- Granted: 1994-09-06
- Earliest claimed: 1991-11-29
- Assignees: Kuraray Co., Ltd.
- Inventors: Taichi Negi; Sumio Itamura; Satoshi Hirofuji
- Web page: https://patentgrep.com/patent/US5344715A

## CPC

- B32B 27/08: of synthetic resin
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 27/22: using plasticisers
- B32B 27/30: comprising vinyl {(co)polymers; comprising acrylic (co)polymers}
- B32B 27/306: {comprising vinyl acetate or vinyl alcohol (co)polymers}
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- C08J 5/18: Manufacture of films or sheets
- B32B 2307/736: Shrinkable
- C08J 2323/08: Copolymers of ethene (C08J2323/16 takes precedence)
- C08J 2329/04: Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
- Y10S 428/913: Material designed to be responsive to temperature, light, moisture
- Y10T 428/1328: Shrinkable or shrunk [e.g., due to heat, solvent, volatile agent, restraint removal, etc.]
- Y10T 428/1383: Vapor or gas barrier, polymer derived from vinyl chloride or vinylidene chloride, or polymer containing a vinyl alcohol unit is sandwiched between layers [continuous layer]
- Y10T 428/31913: Monoolefin polymer
- Y10T 428/31928: Ester, halide or nitrile of addition polymer
- Y10T 428/31935: Ester, halide or nitrile of addition polymer
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A heat shrinkable film or multilayered film comprising at least one layer comprising an EVOH (A) having an average ethylene content of 20 to 60 mol % and an areal shrinkage when immersed in hot water at 90.degree. C. for 1 minute of at least 10% and having thermal characteristics satisfying the following condition (i) 1.ltoreq..vertline.{T(1)-T(2)}-{t(1)-t(2)}.vertline..ltoreq.20 (i) wherein 1.ltoreq..vertline.t(1)-T(1).vertline..ltoreq.20 in the case of T(1)=T(2) and t(1)=t(2) and wherein T(1) and T(2) represent peak temperature (.degree.C.) on the highest temperature side and lowest temperature side respectively in differential scanning calorimetry (DSC) measurement of said EVOH (A) and t(1) and t(2) peak temperatures originating from T(1) and T(2), respectively, in DSC measurement of said EVOH having been treated with an alkaline solvent.

## Claims

### Claim 1

A heat shrinkable film or multilayered film comprising at least one layer comprising an ethylene-vinyl alcohol copolymer (EVOH) (A)) having an average ethylene content of 20 to 60 mole % and an areal shrinkage when immersed in hot water at 90.degree. C. for 1 minute of at least 10% and having characteristics satisfying the following equation (i):
1.ltoreq..vertline.{T(1)-T(2)}-{t(1)-t(2)}.vertline..ltoreq.20 (i)
wherein 1.ltoreq..vertline.t(1)-T(1).vertline..ltoreq.20 in the case of T(1)=T(2) and t(1)=t(2); and
wherein T(1) and T(2) represent peak temperature (.degree.C.) on the highest temperature side and lowest temperature side respectively in differential scanning calorimetry (DSC) measurement of said EVOH (A), and t(1) and t(2) represent peak temperatures on the highest temperature side and lowest temperature side respectively originating from T(1) and T(2), respectively, in DSC measurement of said EVOH (A) after having been treated with an alkaline solvent.

### Claim 2 (depends on 1)

A heat shrinkable film or multilayered heat shrinkable film according to claim 1, having an areal shrinkage when immersed in hot water at 90.degree. C. for 1 minute of at least 30%.

### Claim 3 (depends on 1)

A multilayered film according to claim 1, wherein said layer of said EVOH (A) further comprises 0.1 to 30 parts by weight based on 100 parts by weight of EVOH (A) of a compound (B) satisfying the following equations (iv) and (v), and further having at least one resin layer (D) satisfying the following equation (iv):
5.5.ltoreq.19-CH(A).times.0.1-SP(B).gtoreq.1.5 (iv)
-1.ltoreq.SP(B)-SP(D).ltoreq.3.5 (v)
wherein CH(A) represents the average ethylene content in mole % of EVOH (A), SP(B) represents the solubility parameter (Fedor's formula) of the compound (B) and SP(D) represents the solubility parameter (Fedor's formula) of the resin (D) constituting the resin layer (D).

### Claim 4 (depends on 3)

A multilayered heat shrinkable film according to claim 3, wherein said compound (B) satisfying the conditions (iv) and (v) is a hydrophobic plasticizer.

### Claim 5 (depends on 1)

A heat shrinkable film or multilayered heat shrinkable film according to claim 1, which has an areal shrinkage when immersed in hot water at 90.degree. C. for 1 minute of at least 50%.

### Claim 6 (depends on 1)

A heat shrinkable film or multilayered heat shrinkable film according to claim 1, wherein the uniformity of shrinkage as measured by Y.sub.2 =(maximum temperature-minimum thickness)/average thickness) after heat shrinkage is not more than 3.

### Claim 7 (depends on 1)

A heat shrinkable film or multilayered heat shrinkable film according to claim 1, wherein the index of non-uniform shrinkage Y as determined by the following equation is not more than 5:
Y=Y.sub.2 /Y.sub.1 .ltoreq.5
wherein
Y.sub.1 =(maximum thickness-minimum thickness/average thickness) before heat shrinkage; and
Y.sub.2 =(maximum thickness-minimum thickness/average thickness) after heat shrinkage.