U.S. patent application number 11/719002 was filed with the patent office on 2008-03-06 for heat-shrinkable laminated film, molded product and heat-shrinkable label employing the film, and container.
This patent application is currently assigned to MITSUBISHI PLASTICS, INC.. Invention is credited to Takashi Hiruma, You Miyashita, Jun Takagi, Yukihiro Tanaka, Takeyoshi Yamada.
Application Number | 20080057236 11/719002 |
Document ID | / |
Family ID | 36336559 |
Filed Date | 2008-03-06 |
United States Patent
Application |
20080057236 |
Kind Code |
A1 |
Yamada; Takeyoshi ; et
al. |
March 6, 2008 |
Heat-Shrinkable Laminated Film, Molded Product and Heat-Shrinkable
Label Employing the Film, and Container
Abstract
The present invention provides a heat-shrinkable laminated film,
which exhibits excellent film rigidity, shrink finishing quality,
transparency of the recycled film, and a small natural shrinkage,
with suppressed film interlayer peeling and shrinking stress, and
which is applicable to shrinkable packing, shrinkable bond-packing,
shrinkable label and the like. The heat-shrinkable laminated film
comprises: a surface layer (S layer) composed of a polyester series
resin composition containing a polyvalent carboxylic acid residue
and a polyvalent alcohol residue; a middle layer (M layer) composed
of a styrene series resin composition; and an adhesive layer (AD
layer) which contains a copolymer of styrene series hydrocarbon and
a conjugated dienic hydrocarbon or hydrogenated derivatives
thereof, and having a styrene series hydrocarbon content rate to
the entire copolymer or hydrogenated derivatives is 5.about.40 mass
% or less. An elongation modulus of the film in a direction
perpendicular to a main shrinking direction of the film is 1200 MPa
or more, and a shrinking stress in the main shrinking direction of
the film is 8 MPa or less or a rupture elongation at 23.degree. C.
is 40% or more.
Inventors: |
Yamada; Takeyoshi; (Shiga,
JP) ; Tanaka; Yukihiro; (Shiga, JP) ; Hiruma;
Takashi; (Shiga, JP) ; Miyashita; You; (Shiga,
JP) ; Takagi; Jun; (Shiga, JP) |
Correspondence
Address: |
DARBY & DARBY P.C.
P.O. BOX 770
Church Street Station
New York
NY
10008-0770
US
|
Assignee: |
MITSUBISHI PLASTICS, INC.
5-2, Marunouchi 2-chome, Chiyoda-ku
Tokyo
JP
100-0005
|
Family ID: |
36336559 |
Appl. No.: |
11/719002 |
Filed: |
November 10, 2005 |
PCT Filed: |
November 10, 2005 |
PCT NO: |
PCT/JP05/20653 |
371 Date: |
August 24, 2007 |
Current U.S.
Class: |
428/34.9 |
Current CPC
Class: |
B32B 2307/412 20130101;
B32B 2307/51 20130101; B32B 2307/736 20130101; B32B 25/042
20130101; C09J 2203/334 20130101; B32B 2519/00 20130101; C09J
2467/006 20130101; C09J 2301/162 20200801; C09J 2425/00 20130101;
G09F 3/04 20130101; B32B 7/12 20130101; B32B 2439/00 20130101; C09J
7/29 20180101; B32B 27/308 20130101; B32B 25/08 20130101; B32B
2307/704 20130101; B32B 27/36 20130101; C09J 2425/006 20130101;
Y10T 428/1328 20150115; B32B 25/14 20130101 |
Class at
Publication: |
428/034.9 |
International
Class: |
B65B 53/02 20060101
B65B053/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 10, 2004 |
JP |
2004-326965 |
Nov 10, 2004 |
JP |
2004-326966 |
Claims
1. A heat-shrinkable laminated film comprising: a surface layer (S
layer) comprising a polyester series resin composition comprising a
polyvalent carboxylic acid residue and a polyvalent alcohol
residue; a middle layer (M layer) comprising a styrene series resin
composition; and an adhesive layer (AD layer) comprising a resin
composition containing a copolymer of styrene series hydrocarbon
and a conjugated dienic hydrocarbon or hydrogenated deriviatives
thereof, and having a styrene series hydrocarbon content rate in
the copolymer or hydrogenated derivatives thereof is 5 mass % or
more and 40 mass % or less, wherein the respective layers further
comprise compositions comprised mainly of the following components;
an elongation modulus of the heat-shrinkable laminated film in a
direction perpendicular to a film's main shrinking direction
measured in accordance with JIS K7127 is 1200 MPa or more; and
maximum shrinking stress in the main shrinking direction of the
heat-shrinkable laminated film being dipped in 90.degree. C.
silicone oil for 10 seconds is 8 MPa or less.
2. A heat-shrinkable laminated film comprising: a surface layer (S
layer) comprising a polyester series resin composition containing a
polyvalent carboxylic acid residue and a polyvalent alcohol
residue; a middle layer (M layer) comprising a styrene series resin
composition; and an adhesive layer (AD layer) comprising a resin
composition containing a copolymer of styrene series hydrocarbon
and a conjugated dienic hydrocarbon or hydrogenated derivatives
thereof, and having a styrene series hydrocarbon content rate in
the copolymer or hydrogenated derivatives thereof is 5 mass % or
more and 40 mass % or less. wherein the respective layers further
comprise compositions comprising mainly of the following
components; the heat-shrinkable laminated film is elongated at
least twice or more and 7 times or less in one axial direction at
60.degree. C. or more and 120.degree. C. or less; an elongation
modulus of the heat-shrinkable laminated film in a direction
perpendicular to a film's main shrinking direction measured in
accordance with JIS K7127 is 1200 MPa or more; and maximum
shrinking stress in the main shrinking direction of the said
heat-shrinkable laminated film being dipped in 90.degree. C.
silicone oil for 10 seconds is 8 MPa or less.
3. A heat-shrinkable laminated film according to claim 1, wherein
maximum shrinking stress in the main shrinking direction of the
laminated film being dipped in 90.degree. C. silicone oil for 10
seconds is 5 MPa or more and 8 MPa or less.
4. A heat-shrinkable laminated film according to claim 1, wherein
the polyester series resin composition constituting the surface
layer (S layer) contains amorphous polyethylene terephthalate
series resin as a main component which comprises aromatic
dicarboxylic residue and diol residue, wherein the diol residue
contains 15 mole % or more and 50 mole % or less of 1,4-cyclohexane
dimethanol residue in total diol residue.
5. A heat-shrinkable laminated film comprising: a surface layer (S
layer) comprising a resin composition consisting of an amorphous
polyester series resin containing a polyvalent carboxylic acid
residue and a polyvalent alcohol residue, and 1 part by mass or
more and 40 parts by mass or less of crystalline polyester series
resin to 100 parts by mass of the amorphous polyester series resin;
a middle layer (M layer) comprising a styrene series resin
composition; and an adhesive layer (AD layer) comprising a resin
composition containing a copolymer of styrene series hydrocarbon
and a conjugated dienic hydrocarbon or hydrogenated derivatives
thereof, and having a styrene series hydrocarbon content rate in
the copolymer or hydrogenated derivatives thereof is 5 mass % or
more and 40 mass % or less, wherein the respective layers further
comprise following components; an elongation modulus of the
heat-shrinkable laminated film in a direction perpendicular to a
film's main shrinking direction measured in accordance with JIS
K7127 is 1200 MPa or more; and rupture elongation in the film's
main shrinking direction measured at 23.degree. C. in accordance
with JIS K7127 is 40% or more.
6. A heat-shrinkable laminated film according to claim 1, wherein
the middle layer (M layer) contains 1 part by mass or more and 100
parts by mass or less of resin composition constituting the surface
layer (S layer) to 100 parts by mass of resin composition composing
the middle layer (M layer).
7. A heat-shrinkable laminated film according to claim 1, wherein
the middle layer (M layer) contains 1 part by mass or more and 30
parts by mass or less of resin composition constituting the
adhesive layer (AD layer) to 100 parts by mass of resin composition
composing the middle layer (M layer).
8. A heat-shrinkable laminated film according to claim 5, wherein
the amorphous polyester series resin constituting the surface layer
(S layer) is amorphous polyethylene terephthalate which comprises
aromatic dicarboxylic residue and diol residue, wherein the diol
residue contains 15 mole % or more and 50 mole % or less of
1,4-cyclohexane dimethanol residue in total diol residue.
9. A heat-shrinkable laminated film according to claim 5, wherein
the crystalline polyester series resin constituting the surface
layer (S layer) is at least any one of resins selected from a group
consisting of: polyethylene terephthalate resin, polypropylene
terephthalate resin, polybutylene terephthalate resin, polyethylene
isophthalate resin, polyethylene naphthalate resin, polybutylene
naphthalate resin, polyethylene terephthalate-isophthalate
copolymer resin, polyethylene terephthalate-neopentyl terephthalate
copolymer resin, polybutylene terephthalate-ether copolymer resin,
polybutylene terephthalate-isophthalate copolymer resin, and
polytrimethylene terephthalate.
10. A heat-shrinkable laminated film according to claim 1, wherein
styrene series resin composition constituting the middle layer (M
layer) is selected from a group consisting of: a copolymer of
styrene series hydrocarbon and a conjugated dienic hydrocarbon; a
copolymer of the copolymer with a monomer copolymerable with the
styrene series hydrocarbon or the conjugated dienic hydrocarbon; or
mixtures thereof.
11. A heat-shrinkable laminated film according to claim 1, wherein
a glass transition temperature of copolymer of a styrene series
hydrocarbon and a conjugated dienic hydrocarbon, or hydrogenated
derivatives thereof, which constitutes the adhesive layer (AD
layer), is 20.degree. C. or less.
12. A heat-shrinkable laminated film according to claim 1, wherein
haze measured in accordance with JIS K7105 is 10% or less.
13. A heat-shrinkable laminated film according to claim 1, wherein
a heat shrinking ratio in the main shrinking direction of the
heat-shrinkable laminated film dipped in 70.degree. C. water for 10
seconds is 10% or more and 40% or less, and a heat shrinking ratio
in the main shrinking direction of the heat-shrinkable laminated
film dipped in 80.degree. C. water for 10 seconds is 30% or more
and 70% or less.
14. A heat-shrinkable laminated film according to claim 1,
thickness ratio of the surface layer (S layer) to total film
thickness is 10% or more and 70% or less.
15. A heat-shrinkable laminated film according to claim 1, wherein
rupture elongation of the film at -5.degree. C. measured in
accordance with JIS K7127 after 30 days storage at 30.degree. C. is
100% or more.
16. A molded product employing the heat-shrinkable laminated film
as defined in claim 1 as the base material.
17. A heat-shrinkable label employing the heat-shrinkable laminated
film as defined in claim 1 as the base material.
18. A container provided with the molded product as defined in
claim 16.
19. A container provided with the heat-shrinkable label as defined
in claim 17.
20. A heat-shrinkable laminated film according to claim 2, wherein
the middle layer (M layer) contains 1 part by mass or more and 100
parts by mass or less of resin composition constituting the surface
layer (S layer) to 100 parts by mass of resin composition composing
the middle layer (M layer).
21. A heat-shrinkable laminated film according to claim 2, wherein
the middle layer (M layer) contains 1 part by mass or more and 30
parts by mass or less of resin composition constituting the
adhesive layer (AD layer) to 100 parts by mass of resin composition
composing the middle layer (M layer).
22. A heat-shrinkable laminated film according to claim 2, wherein
the amorphous polyester series resin constituting the surface layer
(S layer) is amorphous polyethylene terephthalate which comprises
aromatic dicarboxylic residue and diol residue, wherein the diol
residue contains 15 mole % or more and 50 mole % or less of
1,4-cyclohexane dimethanol residue in total diol residue.
23. A heat-shrinkable laminated film according to claim 2, wherein
styrene series resin composition constituting the middle layer (M
layer) is selected from a group consisting of: a copolymer of
styrene series hydrocarbon and a conjugated dienic hydrocarbon; a
copolymer of the copolymer with a monomer copolymerable with the
styrene series hydrocarbon or the conjugated dienic hydrocarbon; or
mixtures thereof.
24. A heat-shrinkable laminated film according to claim 2, wherein
a glass transition temperature of copolymer of a styrene series
hydrocarbon and a conjugated dienic hydrocarbon, or hydrogenated
derivatives thereof, which constitutes the adhesive layer (AD
layer), is 20.degree. C. or less.
25. A heat-shrinkable laminated film according to claim 2, wherein
haze measured in accordance with JIS K7105 is 10% or less.
26. A heat-shrinkable laminated film according to claim 2, wherein
a heat shrinking ratio in the main shrinking direction of the
heat-shrinkable laminated film dipped in 70.degree. C. water for 10
seconds is 10% or more and 40% or less, and a heat shrinking ratio
in the main shrinking direction of the heat-shrinkable laminated
film dipped in 80.degree. C. water for 10 seconds is 30% or more
and 70% or less.
27. A heat-shrinkable laminated film according to claim 2, wherein
thickness ratio of the surface layer (S layer) to total film
thickness is 10% or more and 70% or less.
28. A heat-shrinkable laminated film according to claim 2, wherein
rupture elongation of the film at -5.degree. C. measured in
accordance with JIS K7127 after 30 days storage at 30.degree. C. is
100% or more.
29. A heat-shrinkable laminated film according to claim 5, wherein
the middle layer (M layer) contains 1 part by mass or more and 100
parts by mass or less of resin composition constituting the surface
layer (S layer) to 100 parts by mass of resin composition composing
the middle layer (M layer).
30. A heat-shrinkable laminated film according to claim 5, wherein
the middle layer (M layer) contains 1 part by mass or more and 30
parts by mass or less of resin composition constituting the
adhesive layer (AD layer) to 100 parts by mass of resin composition
composing the middle layer (M layer).
31. A heat-shrinkable laminated film according to claim 5, wherein
the amorphous polyester series resin constituting the surface layer
(S layer) is amorphous polyethylene terephthalate which comprises
aromatic dicarboxylic residue and diol residue, wherein the diol
residue contains 15 mole % or more and 50 mole % or less of
1,4-cyclohexane dimethanol residue in total diol residue.
32. A heat-shrinkable laminated film according to claim 5, wherein
styrene series resin composition constituting the middle layer (M
layer) is selected from a group consisting of: a copolymer of
styrene series hydrocarbon and a conjugated dienic hydrocarbon; a
copolymer of the copolymer with a monomer copolymerable with the
styrene series hydrocarbon or the conjugated dienic hydrocarbon; or
mixtures thereof.
33. A heat-shrinkable laminated film according to claim 5, wherein
a glass transition temperature of copolymer of a styrene series
hydrocarbon and a conjugated dienic hydrocarbon, or hydrogenated
derivatives thereof, which constitutes the adhesive layer (AD
layer), is 20.degree. C. or less.
34. A heat-shrinkable laminated film according to claim 5, wherein
haze measured in accordance with JIS K7105 is 10% or less.
35. A heat-shrinkable laminated film according to claim 5, wherein
a heat shrinking ratio in the main shrinking direction of the
heat-shrinkable laminated film dipped in 70.degree. C. water for 10
seconds is 10% or more and 40% or less, and a heat shrinking ratio
in the main shrinking direction of the heat-shrinkable laminated
film dipped in 80.degree. C. water for 10 seconds is 30% or more
and 70% or less.
36. A heat-shrinkable laminated film according to claim 5, wherein
thickness ratio of the surface layer (S layer) to total film
thickness is 10% or more and 70% or less.
37. A heat-shrinkable laminated film according to claim 5, wherein
rupture elongation of the film at -5.degree. C. measured in
accordance with JIS K7127 after 30 days storage at 30.degree. C. is
100% or more.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat-shrinkable laminated
film, a molded product and a heat-shrinkable label employing the
film, and a container. More particularly, the present invention
related to a heat-shrinkable laminated film, which exhibits
excellent shrink finishing quality, film rigidity (stiffness at
room temperature), transparency at a time of addition as a
reclamation material, and a small natural shrinkage and reduction
of mechanical strength over time, with suppressed film interlayer
peeling and shrinking stress, and which is applicable to shrinkable
packing, shrinkable bond-packing, shrinkable label and the like,
and a molded product and a heat-shrinkable label employing the
film, and a container.
BACKGROUND ART
[0002] These days, soft drinks such as juice are sold in a form
that the drink is filled in containers such as glass bottles or SET
(polyethylene terephthalate) bottles. When the drinks are on sale,
in order to differentiate the goods from other goods and to improve
its visibility, a heat-shrinkable label on which printing is given
is provided onto the outside of each container. In addition,
recently, demand of such bottles with heat-shrinkable label thereon
is increasing; a heat-shrinkable label, which exhibits advanced
shrink finishing quality in a relatively short period at low
temperature and small natural shrinkage (it is the circumstance
where a film shrinks before its original use at slightly higher
temperature than room temperature, e.g. in summer.), is required.
Nowadays, as a material for this heat-shrinkable label,
polystyrene, polyester, polyvinyl chloride, polyolefin, and the
like are generally used.
[0003] Among the above materials, polyvinyl chloride series
heat-shrinkable film has problems such as lack of heat resistance
and emission of hazardous gas like hydrogen chloride when it is
burnt after its use. Whereas, polystyrene series heat-shrinkable
film which mainly contains styrene-butadiene copolymer is proposed
and used. This polystyrene series heat-shrinkable film exhibits
excellent shrink finishing quality compared with polyvinyl chloride
series heat-shrinkable film. However, the polystyrene series
heat-shrinkable film also exhibits large natural shrinkage and low
film rigidity (i.e. stiffness at room temperature), this film
causes problems such as fitting defect due to the label bending
during the label fitting process. On the other hand, the polyester
series heat-shrinkable film exhibits positive features such as
small natural shrinkage and high film rigidity. However, the shrink
finishing quality of polyester series heat-shrinkable film is not
as good as that of polyvinyl chloride series film (in other words,
when the film is fitted as a label onto a container, by heat
shrinkage, spots and wrinkles can be easily occurred.), and this
film causes problems such as significant drop of its mechanical
strength over time. Among the problems, embrittlement of the film
over time tends to be caused when the film is stored for long term
under an atmosphere of relatively high temperature, particularly at
30.degree. C. or more. Such film embrittlement becomes a cause of
breakage during film processing, therefore the improvement for
preventing film embrittlement is also required.
[0004] In order to solve the above problems, Patent Document 1
proposes a method to improve shrink finishing quality of the
heat-shrinkable film with use of a resin produced by mixing
modified polybutylene terephthalate resin obtained by
copolymerizing predetermined amount of aromatic dicarboxylic acid
other than terephthalic acid and modified polyester resin at
predetermined ratio. Also, Patent Document 2 proposes a method to
improve shrink finishing quality of the heat-shrinkable film with
use of copolymer polyester resin which is obtained by modifying the
polyvalent alcohol components, particularly 1,4-cyclohexane
dimethanol, 1,4-buthanediol, and polytetramethylene etherglycol.
However, since shrinking stress of these heat-shrinkable films is
not sufficiently reduced, the shrink finishing quality of both
films is not as good as that of styrene series heat-shrinkable
film. Moreover, as shrinking stress is not sufficiently reduced,
crystalline of the film is increased, or glass transition
temperature (hereinafter, it may be described as "Tg".) is lowered.
Therefore, the above films have a problem that reduction of the
mechanical strength thereof over time becomes remarkable.
[0005] As a means to strike a balance between improvement of shrink
finishing quality and prevention of reduction of mechanical
strength over time, a shrinkable label is shown that consists of
surface and backside layers obtained by polyester series resin
containing 1,4-cyclohexane dimethanol as diol component, laminated
on both sides of a middle layer which is obtained by polystyrene
series resin showing good shrink finishing quality and less
embrittlement over time (refer to Patent Document 3.).
Nevertheless, this shrinkable label has a problem in insufficient
interlayer adhesion, thus, in secondary fabrication, interlayer
peeling can be easily caused at a time of printing.
[0006] While, as an art with improved the above interlayer
adhesion, Patent Document 4 reports a film using: a block copolymer
of vinyl aromatic hydrocarbon and a conjugated dien derivatives for
an inner layer; a polyester series copolymer for both sides of
outer layers; and an ethylene-vinyl acetate copolymer, an
ethylene-unsaturated carboxylic acid copolymer and the like for an
adhesive layer. However, this film has a lack of compatibility
between the block copolymer of vinyl aromatic hydrocarbon and the
conjugated dien derivatives for inner layer and an ethylene-vinyl
acetate copolymer for the adhesive layer. When recycled resin
obtained by trimming loss like heels of films and the like is added
(hereinafter, refer to "addition of a reclamation material"), there
is a problem that transparency of the entire film tends to become
poor.
Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No.
2003-12833
Patent Document 2: JP-A No. 2002-212405
Patent Document 3: JP-A No. 2002-351332
Patent Document 4: Japanese Patent Publication of Examined
Application No. 5-33896
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0007] Accordingly, an object of the present invention is to
provide a heat-shrinkable laminated film, which exhibits excellent
shrink finishing quality, film rigidity (stiffness at room
temperature), transparency at a time of addition of a reclamation
material, and a small natural shrinkage and reduction of mechanical
strength over time, with suppressed film interlayer peeling and
shrinking stress, and which is applicable to shrinkable packing,
shrinkable bond-packing, shrinkable label and the like.
[0008] Another object of the present invention is to provide a
molded product and a heat-shrinkable label employing the above film
which is applicable to shrinkable packing, shrinkable bond-packing,
shrinkable label and the like, and a container with which the above
molded product or the heat-shrinkable label is fitted.
Means for Solving the Problems
[0009] The inventors have been conducted serious studies on
individual compositions of a surface layer, an adhesive layer, and
a middle layer constituting the laminated film. As a result, the
inventors have acquired an idea of a film which is capable to solve
the above problems, and completed the present invention. In other
words, an object of the invention is achieved by providing the
following heat-shrinkable laminated film, molded product and
heat-shrinkable label employing the above film, and container with
which the above molded product or heat-shrinkable label is
fitted.
[0010] (1) A heat-shrinkable laminated film comprising: a surface
layer (S layer); a middle layer (M layer); and an adhesive layer
(AD layer), wherein the respective layers are resin compositions
mainly containing following components; an elongation modulus of
the heat-shrinkable laminated film in a direction perpendicular to
a film's main shrinking direction measured in accordance with JIS
K7127 is 1200 MPa or more; and maximum shrinking stress in the main
shrinking direction of the heat-shrinkable laminated film being
dipped in 90.degree. C. silicone oil for 10 seconds is 8 MPa or
less.
[0011] A surface layer (S layer): a polyester series resin
composition containing a polyvalent carboxylic acid residue and a
polyvalent alcohol residue.
[0012] A middle layer (M layer): a styrene series resin
composition.
[0013] An adhesive layer (AD layer): a resin composition containing
a copolymer of styrene series hydrocarbon and a conjugated dienic
hydrocarbon or hydrogenated derivatives thereof, and having a
styrene series hydrocarbon content rate in the copolymer or
hydrogenated derivatives thereof is 5 mass % or more and 40 mass %
or less.
[0014] (2) A heat-shrinkable laminated film comprising: a surface
layer (S layer); a middle layer (M layer); and an adhesive layer
(AD layer), wherein the respective layers are resin composition
mainly containing following components; the heat-shrinkable
laminated film is elongated at least twice or more and 7 times or
less in one axial direction at 60.degree. C. or more and
120.degree. C. or less; an elongation modulus of the
heat-shrinkable laminated film in a direction perpendicular to a
film's main shrinking direction measured in accordance with JIS
K7127 is 1200 MPa or more; and maximum shrinking stress in the main
shrinking direction of the heat-shrinkable laminated film being
dipped in 90.degree. C. silicone oil for 10 seconds is 8 MPa or
less (hereinafter, inventions described in the above (1) and (2)
may be described as "the first embodiment of the invention".).
[0015] A surface layer (S layer): a polyester series resin
composition containing a polyvalent carboxylic acid residue and a
polyvalent alcohol residue.
[0016] A middle layer (M layer): a styrene series resin
composition.
[0017] An adhesive layer (AD layer): a resin composition containing
a copolymer of styrene series hydrocarbon and a conjugated dienic
hydrocarbon or hydrogenated derivatives thereof, and having a
styrene series hydrocarbon content rate in the copolymer or
hydrogenated derivatives thereof is 5 mass % or more and 40 mass %
or less.
[0018] (3) A heat-shrinkable laminated film comprising: a surface
layer (S layer); a middle layer (M layer); and an adhesive layer
(AD layer), the respective layers are resin compositions mainly
containing following components; an elongation modulus of the
heat-shrinkable laminated film in a direction perpendicular to a
film's main shrinking direction measured in accordance with JIS
K7127 is 1200M a or more; and rupture elongation in the film's main
shrinking direction measured at 23.degree. C. in accordance with
JIS K7127 is 40% or more (hereinafter, it may be described as "the
second embodiment of the invention".).
[0019] A surface layer (S layer); a resin composition consisting of
an amorphous polyester series resin containing a polyvalent
carboxylic acid residue and a polyvalent alcohol residue, and 1
part by mass or more and 40 parts by mass or less of crystalline
polyester series resin to 100 parts by mass of the amorphous
polyester series resin.
[0020] A middle layer (M layer): a styrene series resin
composition.
[0021] An adhesive layer (AD layer): a resin composition containing
a copolymer of styrene series hydrocarbon and a conjugated dienic
hydrocarbon or hydrogenated derivatives thereof, and having a
styrene series hydrocarbon content rate in the copolymer or
hydrogenated derivatives thereof is 5 mass % or more and 40 mass %
or less.
[0022] (4) A molded product employing the heat-shrinkable laminated
film as defined in any one of the above (1) to (3) as a base
material.
[0023] (5) A heat-shrinkable label employing the heat-shrinkable
laminated film as defined in any one of the above (1) to (3) as a
base material.
[0024] (6) A container provided with the molded product as defined
in the above (4) or the heat-shrinkable label as defined in the
above (5).
EFFECTS OF THE INVENTION
[0025] According to the present invention, a heat-shrinkable
laminated film, which exhibits excellent shrink finishing quality,
film rigidity (stiffness at room temperature), transparency at a
time of addition of a reclamation material, and a small natural
shrinkage and reduction of mechanical strength over time, with
suppressed film interlayer peeling and shrinking stress, and which
is applicable to shrinkable packing, shrinkable bond-packing,
shrinkable label and the like, can be provided.
[0026] Further, according to the invention, a molded product and a
heat-shrinkable label, which has sufficient film rigidity, exhibits
excellent shrink finishing quality and transparency at a time of
addition of a reclamation material, and a small reduction of
mechanical strength over time, and which is applicable to
shrinkable packing, shrinkable bond-packing, shrinkable label and
the like, can be provided. Moreover, according to the invention, a
container to which products can be adhesively fixed with desired
shrinking stress at a desired position no matter what kind of shape
the fitting product is, and on which a transparent and
clear-looking the above molded product or the heat-shrinkable label
is fitted without having any troubles such as occurrence of
wrinkles, pocks, and insufficient shrinking, is provided.
BEST MODE FOR CARRYING OUT THE INVENTION
[0027] A heat-shrinkable laminated film, a molded product, a
heat-shrinkable label, and a container of the present invention
will be described in detail as follows.
[0028] In this description, "mainly containing" means allowing to
contain other components without preventing from the effects of
resin composing individual layers. The wording is not limiting the
particular content ratio. However, it is a component holding 50
mass % or more, preferably 70 mass % or more, furthermore
preferably 80 mass % or more of the resin composing each layer or
total resin composition. Also, "main shrinking direction" means a
direction of larger heat shrinking ratio in film longitudinal
direction or crosswise direction (width direction). For example,
when the film is fitted onto a bottle, it is a direction equivalent
to outer circumferential direction of the bottle. While, "a
direction perpendicular to" means a direction perpendicular to the
main shrinking direction.
[0029] [A Heat-Shrinkable Laminated Film]
[0030] A heat-shrinkable laminated film of the present invention
(hereinafter, it refers to "film of the invention", unless
otherwise specified, it is understood that both of the first
embodiment and the second embodiment of the inventions are
included.) comprises a surface layer (S layer) mainly containing
polyester series resin composition; a middle layer (M layer)
consisting of styrene series resin composition so as to have
excellent shrink finishing quality and to prevent over-time
embrittlement; and an adhesive layer (AD layer) consisting of a
copolymer of styrene series hydrocarbon and a conjugated dienic
hydrocarbon or hydrogenated derivatives thereof so as to improve
interlayer adhesiveness between the surface layer (S layer) and the
middle layer (M layer).
[0031] <The Surface Layer (S Layer)>
[0032] In the present invention, the surface layer (S layer) is
composed by mainly containing polyester series resin composition
containing a polyvalent carboxylic acid residue and a polyvalent
alcohol residue.
[0033] Examples of the polyvalent carboxylic acid residue
constituting polyester series resin composition of the surface
layer (S layer) include: aromatic dicarboxylic acid residue induced
from such as terephthalic acid, isophthalic acid,
2-chloroterephthalic acid, 2,5-dichloroterephthalic acid,
2-methylterephthalic acid, 4,4-stilbenedicarboxylic acid,
4,4-biphenyldicarboxylic acid, orthophthalic acid, 2,6-naphthalene
dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, bisbenzoic
acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid,
4,4-diphenylether dicarboxylic acid, 4,4-diphenoxyethane
dicarboxylic acid, 5-Na sulfoisophthalic acid,
ethylene-bis-p-benzoic acid; aliphatic dicarboxylic acid residue
induced from such as adipic acid, sebacic acid, azelaic acid,
dodecanedioate, 1,3-cyclohexane dicarboxylic acid, 1,4-cyclohexane
dicarboxylic acid. The polyvalent carboxylic acid residue may be
constituted by one of these polyvalent carboxylic acid residues
alone or in combination with two or more thereof.
[0034] Examples of the polyvalent alcohol residue constituting
polyester series resin composition of the surface layer (S layer)
include glycol residues induced from such as ethylene glycol,
diethylene glycol, 1,2-propylene glycol, 1,3-propanediol,
2,2-dimethyl-1,3-propanediol,
trans-tetramethyl-1,3-cyclobutanediol,
2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-butanediol, neopentyl
glycol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexane
dimethanol, 1,3-cyclohexane dimethanol, decamethylene glycol,
cyclohexanediol, p-xylenediol, bisphenol A, tetrabromo bisphenol A,
tetrabromo bisphenol A-bis (2-hydroxyethylether). The polyvalent
alcohol residue may be constituted by one of these polyvalent
alcohol residues alone or in combination with two or more
thereof.
[0035] In the invention, as the polyester series resin composition
constituting the surface layer (S layer), it is preferable to use
amorphous polyester series resin as a main component consisting of:
at least a kind of residue selected from a group consisting of
terephthalic acid residue, isophthalic acid residue, and
1,4-cyclohexane dicarboxylic acid residue as polyvalent carboxylic
acid residue; and at least a kind of residue selected from a group
consisting of ethylene glycol residue, diethylene glycol residue,
1,4-butanediol residue, 1,4-cyclohexane dimethanol residue,
1,3-cyclohexane dimethanol residue, and polytetramethylene glycol
residue as polyvalent alcohol residue. Moreover, at least either of
polyvalent carboxylic acid residue or polyvalent alcohol residue
preferably consists of two or more residues. By having the above
polyvalent carboxylic acid residue and polyvalent alcohol residue
constituted by plural residues in this way, it is possible to
control the crystalline of the obtained polyester series resin
lower, thereby it is capable to suppress crystallization of the
surface layer (S layer).
[0036] When amorphous polyester resin consists of two or more kinds
of residue, a residue whose mass (mole %) is the largest is defined
as the first residue, and other residues whose mass are less than
the first residue are the second residue and the followers (as it
were, the second residue, the third residue, . . . ). These
residues will be described as follows.
[0037] In the invention, examples of preferable mixture of
polyvalent alcohol residue include a mixture of: ethylene glycol as
the first residue; and at least one kind of residue selected from a
group consisting of 1,4-butanediol, neopentyl glycol, diethylene
glycol, polytetramethylene glycol, and 1,4-cyclohexane dimethanol
as the second residue, preferably 1,4-cyclohexane dimethanol.
[0038] Further, examples of preferable mixture of polyvalent
carboxylic acid residue include a mixture of: terephthalic acid as
the first residue; and at least one kind of residue selected from a
group consisting of isophthalic acid, 1,4-cyclohexane dicarboxylic
acid, succinic acid and adipic acid, preferably isophthalic
acid.
[0039] Total content ratio of polyvalent carboxylic acid residue
and polyvalent alcohol residue of the above second residue and the
followers is, to the sum (200 mole %) of the total amount (100 mole
%) of the polyvalent carboxylic acid residue and the total amount
(100 mole %) of polyvalent alcohol residue, 10 mole % or more,
preferably 15 mole % or more, and 50 mole % or less, preferably 45
mole % or less. When content ratio of the second residue and the
followers is 10 mole % or more, it is capable to control
crystallization of the obtained polyester lower. When content of
the second residue and the followers is 50 mole % or less, it is
capable to utilize the advantages of the first residue.
[0040] For instance, when the polyvalent carboxylic acid residue is
terephthalic acid residue, the first residue of polyvalent alcohol
residue is ethylene glycol residue and the second residue of the
same is 1,4-cyclohexane dimethanol residue; content ratio of
1,4-cyclohexane dimethanol residue as the second residue is, to
total (200 mole %) of total content of terephthalic acid (100 mole
%) as dicarboxylic acid component and total content of ethylene
glycol and 1,4-cyclohexane dimethanol (100 mole %), 10 mole % or
more, preferably 15 mole % or more, and 50 mole % or less,
preferably 45 mole % or less, furthermore preferably 40 mole % or
less. By using ethylene glycol residue and 1,4-cyclohexane
dimethanol residue as diol residues within this range, it is
capable to control crystallization of obtained polyester lower and
to improve rupture-resistance thereof.
[0041] In addition, in the previous example, when the first residue
of polyvalent carboxylic acid residue is terephthalic acid residue
and the second residue of the same is isophthalic acid residue;
content ratio of isophthalic acid residue as polyvalent carboxylic
acid residue and 1,4-cyclohexane dimethanol residue as polyvalent
alcohol residue, to the sum (200 mole %) of the total amount (100
mole %) of terephthalic acid residue and isophthalic acid residue
and the total amount (100 mole %) of ethylene glycol residue and
1,4-cyclohexane dimethanol residue, is in the range of 10 mole % or
more, preferably 15 mole % or more, furthermore preferably 25 mole
% or more, and 50 mole % or less, preferably 45 mole % or less,
furthermore preferably 40 mole % or less.
[0042] In the invention, amorphous polyethylene terephthalate
resin, particularly having terephthalic acid residue as polyvalent
carboxylic acid residue, and having ethylene glycol residue and
1,4-cyclohexane dimethanol residue as polyvalent alcohol residue,
is preferably used.
[0043] Content ratio of 1,4-cyclohexane dimethanol residue, in
total polyvalent alcohol residue, is in the range of 15 mole % or
more, preferably 20 mole % or more, and the upper limit is 50 mole
% or less, preferably 40 mole % or less. When content ratio of the
above 1,4-cyclohexane dimethanol residue is 15 mole % or more,
decline of printability due to the crystallization is small, and it
is capable to suppress over-time embrittlement. While, when content
ratio of 1,4-cyclohexane dimethanol residue is 50 mole % or less,
it is capable to obtain appropriate viscosity at a time of
extrusion melting to obtain moderate film-forming property. There
exists two isomers, i.e. cis-type and trans-type, for
1,4-cyclohexane dimethanol; either of cis-type or trans-type
residue can be used.
[0044] As commercially available above polyester series resin,
"PETG copolyester6763" (produced by Eastman Chemical Company),
"SKYGREEN PETG" (produced by SK Chemicals Co., Ltd.), "VYLON"
(produced by TOYOBO CO., LTD.), and "HYTREL" (produced by Du Pont)
can be the examples.
[0045] In the second embodiment of the invention, a resin
composition constituting the surface layer (S layer) comprises
amorphous polyester series resin containing polyvalent carboxylic
acid residue and polyvalent alcohol residue, and 1 part by mass or
more and 40 parts by mass or less of crystalline polyester resin to
100 parts by mass of the amorphous polyester series resin.
[0046] "Amorphous polyester series resin" in the second embodiment
means a polyester resin such that, by using differential scanning
calorimeter (DSC), when the resin is heated from -50.degree. C. to
300.degree. C. at a heating rate of 10.degree. C./min, then it is
cooled down to -50.degree. C. at a cooling rate of 10 cc/min,
thereafter it is heated up again to 300.degree. C. at a heating
rate of 10.degree. C./min, clear melting peak cannot be observed at
the second heating. Amorphous polyester resin is contained in the
range of 20 mass % or more, preferably 30 mole % or more as
copolymer residue, in the sum (200 mole %) of 100 mole % of
polyvalent carboxylic acid residue and 100 mass % of polyvalent
alcohol residue.
[0047] As polyvalent carboxylic acid residue and polyvalent alcohol
residue constituting the amorphous polyester resin, examples of
residues which is shown in the description of the first embodiment
can be suitably used. In the second embodiment, amorphous polyester
series resin having at least one kind of residue selected from a
group consisting of terephthalic acid residue, isophthalic acid
residue, and 1,4-cyclohexane dicarboxylic acid residue as
polyvalent carboxylic acid residue, and having at least one kind of
residue selected from a group consisting of ethylene glycol
residue, diethylene glycol residue, 1,4-butanediol residue,
1,4-cyclohexane dimethanol residue, 1,3-cyclohexane dimethanol
residue and polytetramethylene glycol residue as polyvalent alcohol
residue, can be preferably used.
[0048] In the second embodiment, a resin composition having an
amorphous polyethylene terephthalate resin as a main component
containing constituent units which consists of terephthalic acid
residue as polyvalent carboxylic acid residue, and ethylene glycol
residue and 1,4-cyclohexane dimethanol residue as polyvalent
alcohol residue, is suitably used. Content ratio of 1,4-cyclohexane
dimethanol residue is, in the range of 15 mole % or more,
preferably 20 mole % or more in total polyvalent alcohol residue,
and the upper limit is 50 mole % or less, preferably 40 mole % or
less. When content ratio of the above 1,4-cyclohexane dimethanol
residue is 15 mole % or more, decline of printability due to the
crystallization is small, and it is capable to suppress over-time
embrittlement. While, when content ratio of 1,4-cyclohexane
dimethanol residue is 50 mole % or less, it is capable to obtain
appropriate viscosity at a time of extrusion melting to obtain
moderate film-forming property.
[0049] The crystalline polyester resin used in the second
embodiment will be described as follows.
[0050] "Crystalline polyester series resin" in the second
embodiment means a polyester resin such that, by using differential
scanning calorimeter (DSC), when the resin is heated from
-50.degree. C. to 300.degree. C. at a heating rate of 10.degree.
C./min, then it is cooled down to -50.degree. C. at a cooling rate
of 10.degree. C./min, thereafter it is heated up again to
300.degree. C. at a heating rate of 10.degree. C./min, clear
melting peak can be observed at the second heating. Such
crystalline polyester series resin also includes copolymer
polyester resin.
[0051] Since the above crystalline polyester series resin has a
different Tg from that of amorphous polyester resin, by mixing the
crystalline polyester series resin in the amorphous polyester
series resin at an appropriate content ratio, it is capable to
adjust shrinking start temperature and to make heat shrinking
behavior relatively gradual. Also, when the crystalline polyester
series resin is mixed into the amorphous polyester resin, it is
capable to improve mechanical strength of the film in film
elongation direction, thereby excellent perforation breakage can be
obtained. In other words, a film having the surface layer (S layer)
constituted only by amorphous polyester series resin exhibits low
solvent resistance and excellent solvent seal property at
bag-making process using organic solvent. Whereas, the mechanical
strength of the film after printing tends to be declined.
Therefore, by containing the crystalline polyester resin in the
amorphous polyester resin, it is capable to give adequate
crystalline and to improve solvent resistance, and to suppress the
decline of mechanical strength of the film after printing.
[0052] Further, by containing the crystalline polyester series
resin in the amorphous polyester series resin and giving
crystalline thereto, it is capable to improve accuracy of thickness
of film after elongation. As it were, if the film to be heated is
studied at partial areas at the initial phase of elongation
process, uneven temperature distribution may sometimes be observed.
In such a circumstance, elongation is started from areas having
higher temperatures. When the resin to be used is amorphous resin,
thinner areas by elongation is further elongated, eventually
elongation of the entire film becomes uneven. However, if the film
contains crystalline resin, the initially elongated areas became
thinner. At the same time, elongation stress became larger due to
the oriented crystallization; therefore non-elongated areas become
easy to be elongated. As a result, the entire film can be evenly
elongated. Thereby it is capable to improve accuracy of film
thickness.
[0053] Examples of the above crystalline polyester series resin
include polyethylene terephthalate resin, polypropylene
terephthalate resin, polybutylene terephthalate resin, polyethylene
isophthalate resin, polyethylene naphthalate resin, polybutylene
naphthalate resin, polyethylene terephthalate-isophthalate
copolymer resin, polyethylene-neopentyl terephthalate copolymer
resin, polybutylene terephthalate-ether copolymer resin,
polybutylene terephthalate-isophthalate copolymer resins
polytrimethylene terephthalate resin. These crystalline polyester
resins may be used alone or in combination with two or more
thereof.
[0054] Among the above, polytrimethylene terephthalate resin,
polybutylene terephthalate resin, polyethylene
terephthalate-isophthalate copolymer resin, or polyethylene
terephthalate-isophthalate copolymer resin are suitably used as
crystalline polyester series resin. Particularly, polytrimethylene
terephthalate resin and polybutylene terephthalate resin are
preferable as these have high crystallinity, it is capable to give
crystallinity to the surface layer (S layer) with small amount of
addition thereof.
[0055] In the second embodiment, the resin composition of the
surface layer (S layer) needs to be a resin such that, to 100 parts
by mass of the above amorphous polyester series resin, 1 part by
mass or more, preferably 5 parts by mass or more, furthermore
preferably 10 parts by mass or more, and 40 parts by mass or less,
preferably 35 parts by mass or less, furthermore preferably 30
parts by mass or less of crystalline polyester resin is mixed. When
the crystalline polyester series resin is 1 part by mass or more,
shrinking behavior becomes gradual, which improves the shrink
finishing quality of the film and mechanical strength in elongation
direction, and which suppresses decline of the film's mechanical
strength after printing and further improves accuracy of the film
thickness. On the other hand, when crystalline polyester resin is
40 parts by mass or less, printability and solvent seal property
are not inhibited, decline of film's mechanical strength over time
is not easily caused, and decline of shrinking property is also
small. Accordingly, it is capable to easily obtain a film which
exhibit excellent shrink finishing quality, thus it is preferable.
An satisfactory crystalline of the mixed resin composition can be
acquired as follows. By using differential scanning calorimeter
(DSC), only the surface layer (S layer) resin composition is heated
from -50.degree. C. to 300.degree. C. at a heating rate of
10.degree. C./min, then it is cooled down to -50.degree. C. at a
cooling rate of 10.degree. C./min, thereafter it is heated up again
to 300.degree. C. at a heating rate of 10.degree. C./min. The
crystal melting calorie (Hm) observed at the second heating is
desirably adjusted in the range of 1 J/g or more, preferably 3 J/g
or more, furthermore preferably 5 J/g or more, and 30 J/g or less,
preferably 25 J/g or less, furthermore preferably 20 J/g or
less.
[0056] In the invention, weight-average molecular weight of
polyester series resin compositions (including amorphous polyester
series resin and crystalline polyester series resin) used for the
surface layer (S layer) are all 30,000 or more, preferably 35,000
or more, furthermore preferably 40,000 or more, and 80,000 or less,
preferably 75,000 or less, furthermore preferably 70,000 or less.
When the weight-average molecular weight thereof is 30,000 or more,
it is capable to inhibit a situation such as shortage of strength
and elongation of the film due to the lack of cohesive force of the
resin and embrittlement caused by that. While, when the
weight-average molecular weight thereof is 80,000 or less, melting
viscosity thereof declines, therefore it becomes suitable for film
production and its efficiency.
[0057] Intrinsic viscosity (IV) of polyester series resin
composition (including amorphous polyester series resin and
crystalline polyester series resin) used for the surface layer (S
layer) is desirably 0.5 dl/g or more, preferably 0.6 dl/g or more,
furthermore preferably 0.7 dl/g or more, and 1.5 dl/g or less,
preferably 1.2 dl/g or less, furthermore preferably 1.0 dl/g or
less. When the intrinsic viscosity (IV) is 0.5 dl/g or more, it is
capable to suppress decline of the film strength property. While,
when the intrinsic viscosity (IV) is 1.5 dl/g or less, it is
capable to inhibit breakage and the like caused by increase of
elongational tension.
[0058] <The Middle Layer (M Layer)>
[0059] In the present invention, as a resin for forming middle
layer (M layer) of the film, a styrene series resin composition is
used. As a styrene series resin composition, copolymer of a styrene
series hydrocarbon and a conjugated dienic hydrocarbon is
preferably used. Examples of a styrene series hydrocarbon include
alkyl styrene such as styrene, (p-, m- or o-methyl styrene), (2,4-,
2,5-, 3,4- or 3,5-dimethyl styrene), (p-t-butyl styrene);
halogenated styrene such as (o-, m- or p-chlorostyrene), (o-, m- or
p-bromo styrene), (o-, m- or p-fluoro styrene), (o-methyl-p-fluoro
styrene); halogenated substitutional alkyl styrene such as (o-, m-
or p-chloromethyl styrene); alkoxy styrene such as (p-, m- or
o-methoxy styrene), (o-, m- or p-ethoxy styrene); carboxy alkyl
styrene such as (o-, m- or p-carboxy methyl styrene); alkyl ether
styrene such as (p-vinylbenzil propylether); alkyl silyl styrene
such as (p-tri-methyl silyl styrene); and furthermore, vinylbenzil
dimethoxy phosphide. The above styrene series resin may contain two
kinds or more of these styrene series hydrocarbon as a monomer
component, it also may contain copolymerable monomer other than
styrene series hydrocarbon.
[0060] Examples of a conjugated dienic hydrocarbon include
butadien, isoprene, 2-methyl-1,3-butadien,
2,3-dimethyl-1,3-butadien, 1,3-pentadien, 1,3-hexadien. The above
styrene series resin may contain two or more of these conjugated
dienic hydrocarbons, it also may contain polymerable monomer other
than conjugated dienic hydrocarbon.
[0061] One of the copolymer of a styrene series hydrocarbon and a
conjugated dienic hydrocarbon suitably used for middle layer (M
layer) is a styrene-butadienic copolymer (SBS) of which styrene
series hydrocarbon is styrene and conjugated dienic hydrocarbon is
butadiene. Styzene content ratio of SBS is 60 mass % or more,
preferably 65 mass % or more, furthermore preferably 70 mass % or
more; the upper limit of styrene content ratio is 95 mass %,
preferably 90 mass %, furthermore preferably 85 mass %. When
styrene content ratio is 60 mass % or more, it is capable to
exhibit an impact-resistant effect. While, when the upper limit is
set to 95 mass %, it is capable to preserve film's elastic modulus
at a temperature hover around room temperature, thereby it is
possible to obtain a film having excellent rigidity. Polymerization
pattern in the case of using styrene-butadien copolymer as styrene
series resin is not particularly limited. It is any one of patterns
selected from block copolymer, random copolymer, and graft
copolymer; it is preferably block copolymer containing pure
structure, random structure, and taper structure.
[0062] Another example of copolymer of a styrene series hydrocarbon
and a conjugated dienic hydrocarbon suitably used in the invention
is styrene-isoprene-butadien block copolymer (SIBS). In SIBS, mass
% ratio of styrene/isoprene/butadien is preferably
(60.about.90)/(5.about.40)/(5.about.30), more preferably
(60.about.85)/(10.about.30)/(5.about.25), furthermore preferably
(60.about.80)/(10.about.25)/(5.about.20). Moreover, MFR measurement
of SIBS (measurement condition: temperature 200.degree. C., load
49N) is desirably 2 g/10 min or more, preferably 3 g/10 min or
more, and 15 g/10 min or less, preferably 10 g/10 min or less,
furthermore preferably 8 g/10 min or less. When content of butadien
is large and content of isoprene is small, butadiene heated in
extruder or the like takes place cross-linking reaction, which
sometimes increases gelatinous material. On the other hand, when
content of butadien is small and content of isoprene is large, unit
price of the materials increase thereby it may cause increase of
production cost.
[0063] The above styrene series resin may be used alone, or mixture
of two or more kinds of styrene series resin respectively having
different styrene content ratio from each other may also be used.
Further, the above styrene series resin may be copolymer of a
styrene series hydrocarbon and a conjugated dienic hydrocarbon
being mixed with copolymer of the above copolymer and copolymerable
monomer with styrene series hydrocarbon or conjugated dienic
hydrocarbon; or homopolymer of styrene series hydrocarbon.
[0064] For example, when the above styrene series resin is a
mixture of SBS and SIBS, mass % ratio of SBS/SIBS is preferably
about (90.about.10)/(10.about.90), more preferably
(80.about.20)/(20.about.80), furthermore preferably
(70.about.30)/(30.about.70).
[0065] For the above styrene series resin composition, when a
copolymer of a styrene series hydrocarbon and an aliphatic
unsaturated carboxylic ester is used, as the above styrene series
hydrocarbon component and aliphatic unsaturated carboxylic ester
component, a copolymer obtained by copolymerizing at least one kind
of compound selected from a group consisting of methyl acrylate or
methacrylate, butyl acrylate or methacrylate, 2-ethylhexyl acrylate
or methacrylate, lauryl acrylate or methacrylate, and stearyl
acrylate or methacrylate can be used. It is preferably a copolymer
of styrene and butyl acrylate or methacrylate, more preferably the
copolymer of which styrene is in the range of 70 mass % or more and
90 mass % or less, Tg (peak temperature of loss elastic modulus
E'') is 50.degree. C. or more and 90.degree. C. or less,
measurement of melt flow rate (MFR) (measurement condition:
temperature 200.degree. C., load 49N) is 2 g/10 min or more and 15
g/10 min or less. The above "acrylate or methacrylate" means
acrylate and/or methacrylate.
[0066] Molecular weight of the above styrene series resin
composition is that the weight-average molecular weight is 100,000
or more, preferably 150,000 or more; and the upper limit thereof is
500,000 or less, preferably 400,000 or less, further more
preferably 300,000 or less. When weight-average molecular weight of
styrene resin composition is 100,000 or more, defects which cause
film deterioration can not be found, thus it is preferable. In
addition, when weight-average molecular weight of styrene series
resin composition is 500,000 or less, there is no need to adjust
the flow property and is no defect like decline of extrusion
property; thus such a molecular weight is preferable.
[0067] Measurement of melt flow rate (MFR) (measurement condition:
temperature 200.degree. C., load 49N) of the above styrene series
resin composition is desirably 2 g/10 min or more, preferably 3
g/10 min or more, and 15 g/10 min or less, preferably 10 g/10 min
or less, furthermore preferably 8 g/10 min or less. When MFR is 2
g/10 min or more, kinematic viscosity at extrusion forming is
appropriate, therefore the above styrene resin composition having
such MFR is excellent in productivity. While, when MFR is 15 g/10
min or less, appropriate cohesive force of resin can be obtained,
thereby mechanical strength of the film is appropriate, and thus
the film is suitable for the practical use.
[0068] Storage elastic modulus (E') at 0.degree. C. of styrene
series resin composition contained in the middle layer (M layer) is
preferably 100.times.10.sup.9 Pa or more, more preferably
1.50.times.10.sup.9 Pa or more. The storage elastic modulus (E') at
0.degree. C. indicates film stiffness, namely, film rigidity. If
the film has 1.00.times.10.sup.9 Pa or more of storage elastic
modulus (E'), when films are laminated, film rigidity (stiffness at
room temperature) can be given to the laminated film. Especially,
if the thickness of the laminated film is made thin, when packaged
film is made to cover containers like PET bottles by using labeling
machines and so on, such film can prevent phenomena of oblique
coverage and decline of yield due to the label bending; thus it is
preferable. This storage elastic modulus (E') can be obtained by
using the above styrene series hydrocarbon and conjugated dienic
hydrocarbon block copolymer, mixture of two or more kinds of the
copolymers, or adding other resins in the range without
deteriorating the transparency.
[0069] When styrene resin composition contained in the middle layer
(M layer) is a block copolymer mixture of a styrene series
hydrocarbon and a conjugated dienic hydrocarbon respectively having
different styrene content ratio from each other or a mixture of the
block copolymer with other resins, appropriate selection of resin
giving rupture-resistance and resin giving stiffness make it
possible to obtain preferable result. In other words, by combining
styrene series hydrocarbon-conjugated dienic hydrocarbon block
copolymer having high rupture-resistance and the above copolymer
having high stiffness, or by mixing styrene series
hydrocarbon-conjugated dienic hydrocarbon block copolymer having
high rupture-resistance and other resin having high stiffness, it
is capable to adjust total composition of those styrene series
hydrocarbon-conjugated dienic hydrocarbon or mixtures thereof with
other types of resin can be adjusted to meet the storage elastic
modulus (E') at desired n.sub.1 and 0.degree. C.
[0070] Preferable examples of styrene series hydrocarbon-conjugated
dienic hydrocarbon block copolymer which is capable to give
rupture-resistance are pure block SBS and random block SBS.
Especially, the storage elastic modulus (E') at 0.degree. C. is
preferably 1.00.times.10.sup.8 Pa or more and 1.00.times.10.sup.9
Pa or less. Moreover, it is preferable that such copolymer has
viscoelastic property such that at least one of peak temperatures
of loss elastic modulus (E'') is -20.degree. C. or less. When the
storage elastic modulus at 0.degree. C. is 1.0.times.10.sup.8 Pa or
more, it is capable to give film rigidity by increasing the
blending amount of resin which can give stiffness. While, at a peak
temperature of the loss elastic modulus (E''), a temperature in low
temperature side mainly means rupture-resistance of the film. This
property may be varied depend on elongation condition. However, in
the condition of pre-elongation, if peak temperature of the loss
elastic modulus (E'') does not exist at -20.degree. C. or less,
giving a sufficient film rupture to the laminated film may become
difficult.
[0071] Examples of resin which is capable to give stiffness to a
film include a copolymer containing styrene series hydrocarbon of
which storage elastic modulus (E') at 0.degree. C. is
2.00.times.10.sup.9 Pa or more, such as block copolymer of a
styrene series hydrocarbon and a conjugated dienic hydrocarbon
whose block structure is controlled, polystyrene, copolymer of
styrene series hydrocarbon and aliphatic unsaturated carboxylic
ester.
[0072] Examples of styrene series hydrocarbon-conjugated dienic
hydrocarbon block copolymer whose block structure is controlled
include SBS of which storage elastic modulus (E') at 0.degree. C.
is 2.00.times.10.sup.9 Pa or more as the property of a
styrene-butadien block copolymer. The styrene-butadien composition
ratio of SBS satisfying the above condition may preferably be
adjusted as follows:
styrene/butadiene=(95.about.80)/(5.about.20).
[0073] A copolymerization method which make it possible to satisfy
the above viscoelastic property will be described as follows. A
part of styrene or butadien is polymerized in a normal manner,
after completion of the polymerization, a mixture of styrene
monomer and butadien monomer is added and the polymerization
reaction is continued. By taking this method, butadien having high
polymerization activity is preferentially polymerized, finally, a
block constituted by single monomer of styrene is made. For
instance, styrene is homopolymerized first, then when the
polymerization is completed, a mixture of styrene monomer and
butadien monomer is added thereto and polymerization is continued.
In the mean time, styrene-butadien block copolymer, having
styrene.cndot.butadien copolymer portion whose ratio of
styrene.cndot.butadien monomer is gradually changed between styrene
block and butadien block, can be obtained. Having such a portion,
it is capable to obtain a polymer having the above viscoelastic
property. In this case, two peaks attributed to the abovementioned
butadien block and styrene block cannot clearly observed, and one
apparent peak can seemingly observed. As it were, in pure block and
block structure like SBS of random block having clear existence of
butadien block, Tg attributed to butadien block mainly exists at
0.degree. C. or less, to raise the storage elastic modulus (E') to
more than the predetermined value becomes difficult. About
molecular weight, it is adjusted under a condition such that MFR
measurement (measurement condition: temperature 200.degree. C.,
load 49N) is 2 g/10 min or more and 15 g/10 min or less. Mixing
amount of styrene-butadien block copolymer which is capable to give
this stiffness is adequately adjusted depends on characteristics of
the heat-shrinkable laminated film. To total amount of resin for
forming the middle layer (N layer), it is desirably adjusted in the
range of 20 mass % or more, preferably 40 mass % or more, and 80
mass % or less, preferably 70 mass % or less. When the mixing
amount of styrene-butadien block copolymer is 80 mass % or less to
total amount of resin, the film stiffness can be largely improved
and the decline of rupture-resistance can be suppressed. Whereas,
when it is 20 mass % or more to total amount of resin, sufficient
stiffness can be given to the film.
[0074] Content ratio of the above styrene resin composition, to
total amount of resin for forming the middle layer (M layer), is 50
mass % or more, preferably 65 mass % or more, furthermore
preferably 80 mass % or more. If general-purpose polystyrene (GPPS)
is contained, since Tg (peak temperature of loss elastic modulus
E'') of GPPS is extremely high like 100.degree. C., the content of
ratio GPPS to be mixed is desirably 40 mass % or less, preferably
30 mass % or less, furthermore preferably 20 mass % or less to
total amount of resin for forming the middle layer (M layer).
[0075] Styrene resin contained in the middle layer (M layer) may
have mixing of other resins, if 50 mass % or more of the styrene
series resin is contained to total amount of resin for forming the
middle layer (M layer) as mentioned above. Examples of such other
resin include polyester series resin, polyolefin series resin,
acrylic resin, polycarbonate resin. Among them, polyester series
resin is preferably used.
[0076] The middle layer (M layer) of the invention may include
resin composition constituting main components of the surface layer
(S layer) and adhesive layer (AD layer). If the middle layer (M
layer) can accept the resin composition constituting main
components of the surface layer (S layer) and adhesive layer (AD
layer), for example, it is possible to reuse recycled films
obtained by trimming loss like heels of films, thereby production
cost of the film can be reduced.
[0077] When the middle layer (M layer) include resin composition
constituting the surface layer (Slayer), to 100 parts by mass of
the resin constituting the middle layer (M layer), the resin
constituting the surface layer (S layer) is desirably 1 part by
mass or more and 100 parts by mass or less, preferably 80 parts by
mass or less, furthermore preferably 60 parts by mass or less. When
the resin composition constituting the surface layer (S layer) is
100 parts by mass or less, it is capable to prevent the decline of
film's mechanical strength and to preserve the transparency of the
film at a time of addition of a reclamation material.
[0078] While, when the middle layer (M layer) include resin
composition constituting the adhesive layer (AD layer), to 100
parts by mass of the resin constituting the middle layer (M layer),
the resin constituting the adhesive layer (AD layer) is desirably 1
part by mass or more and 30 parts by mass or less, preferably 25
parts by mass or less, furthermore preferably 20 parts by mass or
less. When the resin composition constituting the adhesive layer
(AD layer) is 30 parts by mass or less, it is capable to preserve
film rigidity and to suppress the natural shrinkage ratio. On the
other hand, when it is 1 part by mass or more, it is capable to
improve rupture-resistance and adhesiveness of the film.
[0079] Moreover, styrene series resin composition constituting
middle layer (M layer), at the time of forming non-elongation film,
is a resin composition desirably giving 1000 MPa or more,
preferably 1100 MPa or more, furthermore preferably 1200 MPa or
more of elongation modulus in a direction perpendicular to main
shrinking direction. If it is possible to give 1000 MPa or more of
elongation modulus, rigidity of the entire laminated film is
strong. Especially, when thickness of the laminated film is made
thinner, problems (such as a phenomena of oblique coverage or film
bending, and decline of yield thereby at a time of fitting of a
packaged film to cover containers like PET bottles by using
labeling machines and so on) cannot be found. Thus this elongation
modulus is preferable.
[0080] The above "non-elongation film" means a film made of styrene
series resin composition as the raw material; it is a film which
can be obtained without elongation at the time of film forming.
[0081] Examples of a commercially available product of the above
styrene series resin composition include "CLEAREN" (produced by
DENKI KAGAKU KOGYO KABUSHIKI KAISHA.), "Asaflex" (produced by Asahi
Kasei Chemicals Corporation.), "styroflex" (produced by BASD Japan
Ltd.), "K-resin" (produced by Chevron Phillips Chemical
International Ltd.).
[0082] <The Adhesive Layer (AD Layer)>
[0083] In the present invention, the adhesive layer (AD layer)
includes copolymer of a styrene series hydrocarbon and a conjugated
dienic hydrocarbon, or hydrogenated derivatives thereof. As a
styrene series hydrocarbon, styrene is preferably used, styrene
congener such as .alpha.-methyl styrene can also be used. Examples
of a conjugated dienic hydrocarbon include 1,3-butadiene, isoprene,
1,3-pentadien; these can be used alone or in combination with two
or more thereof. Furthermore, the adhesive layer (AD layer) may
include a small amount of a third component other than a styrene
series hydrocarbon and a conjugated dienic hydrocarbon. When double
bonds come from mainly vinyl bond of a conjugated dienic
hydrocarbon part exist in large number, affinity with polyester
series resin of the surface layer (S layer) is generated, and it is
preferable to improve the interlayer adhesive strength (interlayer
peeling strength).
[0084] When a copolymer of a styrene series hydrocarbon and a
conjugated dienic hydrocarbon, or hydrogenated derivatives thereof
is used as the adhesive layer (AD layer), content ratio of the
styrene series hydrocarbon, to total amount of copolymer or
hydrogenated derivatives thereof, is importantly 5 mass % or more,
preferably 7 mass % or more, furthermore preferably 10 mass % or
more, and 40 mass % or less, preferably 37 mass % or less,
furthermore preferably 35 mass % or less. It content ratio of the
styrene series hydrocarbon is 5 mass % or more of total amount,
when recycled film is added to the surface layer (S layer), middle
layer (M layer) or the surface layer (S layer) and middle layer (M
layer), compatibility of film is excellent and a film whose
transparency is preserved can be obtained; therefore it is
preferable. On the other hand, if content ratio of the styrene
series hydrocarbon is 40 mass % or less of total amount, the
adhesive layer (AD layer) has rich in flexibility. For instance,
when stress or impact is given to the entire film, damping effect
to the stress generated between the surface layer (S layer) and the
middle layer (M layer) works, thereby it is capable to suppress the
interlayer peeling.
[0085] Glass transition temperature (Tg) of a copolymer of a
styrene series hydrocarbon and a conjugated dienic hydrocarbon is
preferably 20.degree. C. or less, more preferably 10.degree. C. or
less, furthermore preferably 0.degree. C. or less. If the glass
transition temperature (Tg) is 20.degree. C. or less, since
flexible adhesive layer (AD layer) can become a damper when the
laminated film receives stress. Thereby it is capable to suppress
the interlayer peeling and therefore practically preferable.
[0086] The Tg in the invention is calculated as follows. As it
were, firstly, with use of viscoelastic spectrometer DVA-200
(produced by IT Measurement Co., Ltd.), loss elastic modulus (E'')
is measured under the condition of vibrational frequency 10 Hz,
distortion 0.1%, and rate of temperature increase 3.degree. C./min.
From the obtained data, peak value of loss elastic modulus (E'') is
calculated; the temperature at the peak is defined as Tg. In case
that plurality of peaks of loss elastic modulus (E'') exist, the
temperature of peak value whose loss elastic modulus (E'') is the
highest is defined as Tg.
[0087] Examples of commercially available product of the above
copolymer include styrene-butadien block copolymeric elastomer
(commodity name "Toughprene" produced by Asahi Kasei Chemicals
Corporation.), hydrogenated derivatives of styrene-butadien block
copolymer (commodity name "Tuftec H" produced by Asahi Kasei
Chemicals Corporation.: commodity name "Kraton G" produced by Shell
Chemicals Japan Ltd.), hydrogenated derivatives of styrene-butadien
random copolymer (commodity name "Dynalon" produced by JSR
Corporation), hydrogenated derivatives of styrene-isoprene block
copolymer (commodity name "Septon" produced by Kuraray),
styrene-vinyl isoprene block copolymeric elastomer (commodity name
"Hybrar" produced by Kuraray).
[0088] By introducing polar group into a copolymer of a styrene
series hydrocarbon and a conjugated dienic hydrocarbon, or
hydrogenated derivatives thereof, interlayer peeling strength
(interlayer adhesiveness) with the surface layer (S layer)
constituted by polyester series resin composition can be further
improved. Examples of polar groups to be introduced include
anhydride group, carboxylic acid, carboxylic acid ester group,
carboxylic acid chloride group, carboxylic amide group, carboxylic
base group, sulfonic group, sulfonate group, sulfonic chloride
group, sulfonic amide group, sulfonic base group, epoxy group,
amino group, imide group, oxazoline group, hydroxyl group. These
copolymers can be used alone or in combination with two or more
thereof.
[0089] Examples of copolymer of a styrene series hydrocarbon and a
conjugated dienic hydrocarbon, or hydrogenated derivatives thereof
to which the above polar groups are introduced typically include
maleic anhydride modified SEBS, maleic anhydride modified SEPS,
epoxy modified SEBS, epoxy modified SEPS. Particularly, commodity
name "Tuftec M" produced by Asahi Kasei Chemicals Corporation. and
commodity name "EPOFRIEND" produced by DAICEL CHEMICAL INDUSTRIES,
LTD. are available.
[0090] As a resin composition constituting the adhesive layer (AD
layer), not only the above styrene series hydrocarbon-conjugated
dienic hydrocarbon copolymer and the like, a mixed resin of a
polyester series resin used for the surface layer (S layer) and a
styrene series resin for the middle layer (M layer) can be used. By
using the mixed resin for the adhesive layer, it is capable to
adhere polyester series resin contained in the surface layer (S
layer) and polyester resin component contained in the adhesive
layer (AD layer), and to adhere styrene series resin contained in
the middle layer (M layer) and styrene series resin contained in
the adhesive layer (AD layer); thereby it is capable to improve
interlayer adhesive strength. A (Polyester series resin/styrene
series resin) mixing ratio in the mixed resin is, from the view
point of improvement of adhesive effect with neighboring layers, in
mass % ratio, it is (20.about.80)/(80.about.20), preferably
(30.about.70)/(70.about.30), furthermore preferably
(40.about.60)/(60.about.40). By having 20 mass % or more of both of
the resins constituting the adhesive layer, an excellent adhesive
effect with the corresponding layer can be obtained.
[0091] In the invention, to the surface layer (S layer), the middle
layer (M layer), and the adhesive layer (AD layer), unless
otherwise causing remarkable inhibition of the invention, not only
the abovementioned component, for the purpose of workability,
productivity, and improvement/adjustment of various properties of
the heat-shrinkable film, recycled resin obtained by trimming loss
like heels of films; inorganic particles such as silica, talc,
kaolin; pigment such as titanium oxide and carbon black; additive
agents such as fire retardant, weather-resistance stabilizer, heat
resistance stabilizer, antistatic agent, melt viscosity improver,
cross-linker, lubricant, nucleating agent, plasticizer, and
antiaging agent, can be added, if necessary. The recycling resin
obtained by trimming loss like heels of films and so on is
desirably added to the surface layer (S layer) and the middle layer
(M layer), preferably to the middle layer (M layer).
[0092] In the film of the invention, a layer which can give heat
resistance property (hereinafter, refer to "heat resistant layer".)
can be formed onto the surface layer (S layer). As materials
constituting the heat resistant layer, for example, various kinds
of surfactant can be used. Surfactants has been commonly known to
be used as antistatic agent, and also known that it can give
antistatic and static-stopping effect by mixing with certain resins
and forming coat layers on the film surface. However, the fact that
surfactants can give heat resistance has not been commonly known.
The present inventors have been conducted serious studies about
surfactant. As a result, the present inventors have acquired an
idea that, by laminating surfactants (particularly cation series
surfactant or amphoteric surfactant) on the surface layer (S
layer), heat resistance of the film can be improved. By forming
such heat resistant layer on the surface layer (S layer), for
example, when PET bottles for heating use is heated by heater, it
is possible to effectively prevent the film fitted to PET bottles
from fusion-bond to hot plate and the films fitted to PET bottles
from adhering each other.
[0093] The above surfactant is not particularly limited; carious
kinds of surfactant can be used. Examples of anionic surfactant
include low molecular compounds such as fatty acid amine salt,
alkyl phosphate type, alkyl sulfate type, and alkyl aryl sulfate
type; further, high molecular compounds such as poly alkylene
sulfate and copolymer thereof. Examples of cationic surfactant
include alkyl amine sulfate type quaternary ammonium salt type,
quaternary ammonium resin type, pyridium salt, morpholine
derivatives. While, examples of non-ionic surfactant include
sorbitan type, ether type, amine type, amide type, ethanol amide
type, fatty acid glycerin ester, and alkyl polyethylene imine.
Also, examples of zwitterionic surfactant include alkyl betaine
type, alkyl imidazoline derivatives, N-alkyl, and .beta.-alanine
type.
[0094] The above heat resistant layer can be formed by applying
embrocation obtained by solving the above surfactant in solvent. As
the solvent, water or mixture of water and water-soluble organic
solvent can be used. Preferable examples of the above water-soluble
organic solvent include: alcohols such as methanol, ethanol,
isopropyl alcohol, n-propyl alcohol, tert-butyl alcohol,
1,2-propylene alcohol; glycols such as ethylene glycol, propylene
glycol, diethylene glycol, ethylene glycol monomethyl ether,
ethylene glycol monoethylether, ethylene glycol monobutylether,
diethylene glycol monomethylether, ethylene glycol monophenylether,
or derivatives thereof; ketones such as acetone, diacetone alcohol;
and water-soluble ethers, water-soluble esters.
[0095] Examples of coating method to the surface layer (S layer)
include spray coating method, air knife coating method, river
coating method, kiss coating method, gravure coating method,
reverse roll coating method, dies coating method, Meyer bar coating
method, roll-brush coating method, bar coating method, reverse kiss
coating method, offset gravure coating method, doctor blade method,
curtain coating method, dipping method. These may be used alone or
in combination with two or more thereof. The amount of embrocation
is not particularly limited. However, in order to obtain a
desirable heat resistant effect, as the solid portion, it is
preferably in the range of 0.0005 g/m.sup.2 or more and 0.5
g/m.sup.2 or less, preferably 0.001 g/m.sup.2 or more and 0.1
g/m.sup.2 or less.
[0096] <Configuration of Film Layer>
[0097] The heat-shrinkable laminated film of the present invention
is not particularly limited as long as it is at least a film of
three-layers configuration having an adhesive layer (AD layer)
between the surface layer (S layer) and middle layer (M layer). The
middle layer (M layer) may be single layer or multilayer; the
multilayer may has layers therein equivalent to the surface layer
(S layer).
[0098] A preferable lamination configuration for the invention is a
five-layers configuration having the surface layer (S layer)/the
adhesive layer (AD layer)/the middle layer (M layer)/the adhesive
layer (AD layer)/the surface layer (S layer). By applying the layer
configuration, the purpose of the invention such as excellent
shrink finishing quality, film rigidity, transparency at a time of
addition of a reclamation material, and a small natural shrinkage
and reduction of mechanical strength over time, with suppressed
film interlayer peeling and shrinking stress, and which is
applicable to shrinkable packing, shrinkable bond-packing,
shrinkable label and the like in productive and economical way.
[0099] Now, one of the suitable embodiments of a five-layers
configuration film having (S layer)/(AD layer)/(M layer)/(AD
layer)/(S layer) consists of the surface layer (S layer), the
middle layer (M layer), and the adhesive layer (AD layer), will be
described as follows.
[0100] Thickness ratio of each layer can be set in accordance with
the above effects and functions, it is not particularly limited. In
the invention, thickness ratio of the surface layer (S layer) to
the entire film is 10% or more, preferably 20% or more, the upper
limit is 70% or less, preferably 65% or less. Further, thickness
ratio of the middle layer (M layer) to the entire film is 20% or
more, preferably 30% or more, the upper limit is 80% or less,
preferably 70% or less. Thickness of the adhesive layer (AD layer),
from the view point of its function, is in the range of 0.5 .mu.m
or more, preferably 1 .mu.m or more, and 6 .mu.m or less,
preferably 5 .mu.m or less. If the thickness of respective layers
are within the above range, a heat-shrinkable laminated film which
exhibits excellent film rigidity (stiffness at room temperature),
shrink finishing quality, transparency at a time of addition of a
reclamation material, and a small natural shrinkage and reduction
of mechanical strength over time, with suppressed film interlayer
peeling and shrinking stress, and which is applicable to shrinkable
packing, shrinkable bond-packing, shrinkable label and the like can
be obtained in a favorable balance.
[0101] When a heat resistant layer is placed on the surface layer
(S layer), the heat resistant layer is applied so as to become a
thickness of 0.0006 g/m.sup.2 or more, preferably 0.0015 g/m.sup.2
or more, further preferably 0.0045 g/m.sup.2 or more. If the
desired heat resistance can be obtained by the application,
furthermore application is not needed. Maximum amount and thickness
of application can be set in line with the cost.
[0102] <Physical and Mechanical Properties of the Film>
[0103] The film of the present invention need to have 1200 MPa or
more of elongation modulus in a direction perpendicular to the main
shrinking direction measured in accordance with JIS K7127, more
preferably 1300 MPa, furthermore preferably 1400 MPa or more. Upper
limit of the elongation modulus of normally used heat-shrinkable
laminated film is about 3000 MPa, preferably about 2900 MPa,
furthermore preferably about 2800 MPa. When the elongation modulus
is 1200 MPa or more, rigidity of the entire film (stiffness at room
temperature) is high. Especially, if the thickness of the laminated
film is made thin, when packaged film is made to cover containers
like PET bottles by using labeling machines and so on, such film
can prevent phenomena of oblique coverage and decline of yield due
to the label bending; thus it is preferable. The above elongation
modulus is measured at 23.degree. C. in accordance with JIS
K7127.
[0104] In this description, the "main shrinking direction" of the
film means a direction of larger elongation in comparison with the
longitudinal direction and the crosswise direction. For example,
when the film is fitted onto a bottle, it is a direction equivalent
to outer circumferential direction of the bottle.
[0105] In the film of the invention, the rupture elongation in the
film main shrinking direction needs to be 40% or more at 23.degree.
C. measured in accordance with JIS K7127. It is preferably 50% or
more, further preferably 60% or more. The upper limit of rupture
elongation of normally used heat-shrinkable laminated film is about
100% or more and 200% or less.
[0106] In the film of the invention, the rupture elongation in a
direction perpendicular to the film main shrinking direction at
-5.degree. C. measured in accordance with JIS K7127 is 100% or
more. It is preferably 200% or more, furthermore preferably 300% or
more.
[0107] Moreover, in the film of the invention, the rupture
elongation in a direction perpendicular to the film main shrinking
direction at -5.degree. C., after 30 days storage at 30.degree. C.,
measured in accordance with JIS K7127 is 100% or more. It is
preferably 200% or more, furthermore preferably 300% or more.
[0108] The rupture elongation is an index to guess a resistance to
the perforation breakage of heat-shrinkable label. The
"perforation" means one or two or more perforated lines processed
in advance on labels so as to easily open up the labels or cap
seals fitted onto plastic bottles or glass bottles by heat
shrinking, and to easily peel such labels from bottles or glass
bottle at a time of recycling. The perforation process is usually
done with use of perforation cutter at a time of center seal
processing. The "perforation breakage" means a phenomenon such that
when shrinkable labels are fitted to bottles and the labeled
bottles are transported to and sold in shops, for instance, if
impact is given on a bottle by falling down of the bottle on the
ground, stress is concentrated on the perforated part thereby the
perforation is broken. Therefore, perforation breakage is not
preferable. When it is a film of which rupture elongation in the
film main shrinking direction is 40% or more at 23.degree. C.,
perforation breakage is difficult to be occurred even when impact
is given on the bottles; thus it is practically preferable. On the
other hand, when it is a film of which rupture elongation in the
direction perpendicular to the film's main shrinking direction is
100% or more at -5.degree. C., a sufficient mechanical strength can
be obtained even at low temperatures, and the film breakage is
difficult to be occurred; thus it is practically preferable. In
addition, it the rupture elongation over time is 100% or more, even
after long time storage, the mechanical strength is preserved, the
film is difficult to be broken during printing and film-fitting
processes. Thus, it is practically preferable.
[0109] Rupture elongation is measured in accordance with JIS K7127,
in particular, at 23.degree. C. or -5.degree. C., to the film's
main shrinking direction or the direction perpendicular thereto,
individual films can be evaluated by conducting tensile test of
which testing rate 200 mm/min.
[0110] In the heat-shrinkable laminated film of the invention, it
is important that heat shrinkage ratio in the main shrinking
direction when heated in 70.degree. C. water for 10 seconds is 10%
or more and 40% or less, preferably 10% or more and 35% or less; it
is also important that the heat shrinkage ratio in the main
shrinking direction when heated in 8000 water for 10 seconds is 30%
or more and 70% or less, preferably 35% or more and 65% or
less.
[0111] The heat shrinkage ratio at the above temperatures is an
index of judging adaptability to the relatively short-time (several
seconds to dozen seconds) shrinking process of label shrinkage for
PET bottles. For example, necessary heat shrinkage ratio required
for heat-shrinkable film which is applicable to shrinkable labels
for PET bottles is varied depend on the shapes, in general, it is
20% or more and 70% or less.
[0112] A heat shrink machines, currently industrially most widely
used for label fitting to PET bottles, is the so-called "steam
shrinker" using water vapor as a heating medium for shrinking
process. The heat-shrinkable film, from the view point of influence
of heat to objects to be covered, is necessary to be sufficiently
heat shrink at as low temperatures as possible. Nevertheless, it
the film is highly heat dependent and its heat shrinkage ratio is
extremely different depends on the heat, parts of which shrinkage
behavior is different can be easily caused by temperature spots in
the steam shrinker. Because of this, shrinking spots, wrinkles, and
pocks are produced, thereby shrink finishing quality appearance
tends to become worse. From the view point of industrial
productivity, if the film has a heat shrinkage ratio within the
range of the above condition, the film can sufficiently adhere to
the objects to be covered within a certain shrinking time, and does
not produce shrinking spots, wrinkles, and pocks. An excellent
shrink finishing quality appearance can be obtained, thus it is
preferable.
[0113] When the film of the invention is used as a heat-shrinkable
label, the shrinkage ratio of longitudinal direction (the direction
perpendicular to the main shrinking direction) when heated in
80.degree. C. water for 10 seconds is preferably 10% or less and 5%
or less, furthermore preferably 3% or less. Also, When heated in
70.degree. C. water for 10 seconds, the shrinkage ratio is
preferably 10% or less, and further preferably 5% or less,
furthermore preferably 3% or less. This has to be noted that if the
shrinkage ratio of the film in the direction perpendicular to the
main shrinking direction is 10% or less, problems, like shortening
of dimensions in the direction perpendicular to the main shrinking
direction after shrinkage, or easily caused distortion of printed
patterns or letters after shrinkage, and longitudinal sink mark in
the case of bottle of prismatic shape, are difficult to be
appeared; thus it is preferable.
[0114] In the film of the invention, the gap between the heat
shrinkage ratio in the film main shrinking direction when heated in
70.degree. C. water for 10 seconds and the heat shrinkage ratio in
the film main shrinking direction when heated in 80.degree. C.
water for 10 seconds is desirably 40% or less, preferably 35% or
less, further preferably 30% or less. By keeping the gap of heat
shrinkage ratio within the range of 40% or less at 70.degree. C.
and 80.degree. C., at a time of bottle labeling, it is capable to
inhibit uneven shrunk attributed by the uneven temperature of
vapor; consequently, it is possible to inhibit wrinkles, pocks and
the like.
[0115] Natural shrinkage ratio of the film of the invention is
desirably small. In general, natural shrinkage ratio of heat
shrinkable film is, for example, 3.0% or less after 30 days storage
at 30.degree. C., preferably 2.0% or less, further preferably 1.5%
or less. When the natural shrinkage ratio of heat-shrinkable film
is 3.0% under the above condition, even though the produced film is
stored for long period, it is possible to stably fit the label to
the object containers and it is practically difficult to cause
problems.
[0116] Transparency of the film of the invention, haze measured in
accordance with JIS K7105 is preferably 10% or less, further
preferably 7% or less, furthermore preferably 5% or less. When haze
is 10% or less, transparency of film can be obtained, thereby
display effect can be obtained.
[0117] In addition, even when the middle layer (M layer) contains,
to 100 parts by mass of resin constituting the middle layer (M
layer), 1 part by mass or more and 30 parts by mass or less of
resin consisting the surface layer (S layer) and/or the adhesive
layer (AD layer) (e.g., when recycled resin obtained by trimming
loss like heels of films and the like is added), the film of the
invention can keep its haze of a film with thickness 50 .mu.m
measured in accordance with JIS K7105 in the range of 10% or less,
preferably 7% or less, further preferably 5% or less. When haze of
the film of the invention is 10% or less after addition of a
reclamation material of the surface layer (S layer) and/or the
adhesive layer (AD layer) to the middle layer (M layer), it is
possible to have excellent transparency even though it is a
recycled product.
[0118] In the film of the invention, film's maximum shrinking
stress in the film main shrinking direction when soaked in
90.degree. C. silicone oil for 10 seconds is desirably 8.0 MPa or
less, preferably 7.5 MPa or less, further preferably 7.0 MPa or
less. The lower limit of the above shrinking stress is: for the
first embodiment, 4.0 MPa or more, preferably 4.5 MPa or more,
furthermore preferably 5.0 MPa or more; for the second embodiment,
1.0 MPa or more, preferably 1.5 MPa or more, furthermore preferably
2.0 MPa or more. When the maximum shrinking stress is 8.0 MPa or
less, when label fitting is conducted by the steam shrinker, to
temperature spots in the shrinker, parts whose film shrinking
behavior is different can be difficult to be produced, spots,
wrinkles, pocks are also difficult to be produced. Therefore, the
shrink finishing quality is excellent. Moreover, when the label is
used for PET bottle with hot drinks, it is preferable that the film
can inhibit contents overflow. On the other hand, when the maximum
shrinking stress is 1.0 MPa or more, preferably 5.0 MPa or more,
for example, if the label is fitted to the bottle by heat
shrinking, the label and the bottle are completely adhered each
other and the shrink finishing quality thereof is excellent.
Therefore, it is preferable that the so-called "tomomawari
(rotation to each other) (a phenomenon that a label and a bottle
are misaligned; for instance, a printed image of the label supposed
to be at a panel face of prismatic-shape bottle comes off to the
bottle edge, visibility is spoiled, thereby it is not preferable.)"
can be inhibited. Further, these days, due to the development of
thin-walled bottles, when PET bottles in various shapes which are
filled with contents, it expands by the inner pressure, which may
also spoil the appearance of the bottles. To this problem, if the
maximum shrinking stress is 1.0 MPa or more, preferably 5.0 MPa or
more, the film can give a sufficient effect of correcting the
bottle expansion with use of the film stress. Thus, it is
preferable.
[0119] Seal strength of the film of the invention, which is
measured by the measuring method described in following examples,
is 3N/15 mm width or more, preferably 4N/15 mm width or more,
furthermore preferably 5N/15 mm width or more, and 15N/15 mm width
or less, 12N/15 mm width or less. The "seal strength" means a
peeling strength of the seal portion made at a time of film
packaging by below-mentioned center seal. It is important that if
interlayer adhesiveness between the surface layer (S layer) and the
adhesive layer (AD layer) or the adhesive layer (AD layer) and
middle layer (M layer) is poor, at a time of seal strength
measurement, it is not the peeling between a pair of film surface,
but interlayer peeling is possibly going to be proceeded prior to
the peeling between the film surfaces; therefore sufficient seal
strength cannot be secured. The film of the invention has a
sufficient interlayer adhesiveness, as seal strength thereof is
3N/15 mm width or more, there is not a trouble like peeling of
sealing part when used.
[0120] <Production Method of the Film>
[0121] The film of the present invention can be produced by
commonly known methods. As film shapes, it may be flat-type or
tube-type, from the view point of productivity (possibility to take
several cut-films as film products to the original film in the
width direction) and feasibility of printing on the inner surface,
flat-type is preferable. As a production method of flat-type film,
for instance, resins are firstly melted with use of plurality of
extruders, and the melted resins are co-extruded from T-dies. The
co-extruded material is cooled and become solidified by using
chilled roll, then elongated with roll in the longitudinal
direction and with tenter in the crosswise direction, annealed,
cooled, and finally winded by a winder (if the film surface is to
be printed, the surface is treated by corona discharge treatment
before winded), so as to obtain the film. The flat-type film can
also be obtained by open up a film produced by tubular film
process.
[0122] Among properties of the above films, shrinking property and
shrinking stress mainly depend on the elongation temperature and
elongation magnification. When the magnification is larger and
elongation temperature is lower, both of shrinking property and
shrinking stress become larger, moreover, the film is influenced by
thermal treatment (annealing, particularly relaxation thermal
treatment) being conducted after elongation. Elongation temperature
needs to be varied depend on Tg of resin composition to be used or
the required properties of the film. It is controlled in the range
of about 60.degree. C. or more, preferably 70.degree. C. or more,
furthermore preferably 80.degree. C. or more, and the upper limit
is 130.degree. C. or less, preferably 120.degree. C. or less,
furthermore preferably 110.degree. C. or less. When the elongation
temperature is 60.degree. C. or more, the film exhibits excellent
elongation, but also it is easier to adjust the shrinking stress
set in the invention below the upper limit (8 MPa or less).
Whereas, when the elongation temperature is 130.degree. C. or less,
elastic modulus of the materials can be appropriately preserved; it
is easier to obtain excellent film in thickness accuracy,
especially when the film is elongated at a temperature of
120.degree. C. or less, adjustment of lower limit of the maximum
shrinking stress can become easier.
[0123] Depend on the properties of resin composition to be used,
elongation means, elongation temperature, and object product
shapes, elongation magnification is suitably determined in the main
shrinking direction in the range of 1.5 times or more, preferably
twice or more, more preferably 3 times or more, furthermore
preferably 4 times or more, and 10 times or less, preferably 7
times or less, along monoaxial or biaxial directions. Especially,
when the magnification is particularly 7 times or less, it is
easier to adjust the maximum shrinking stress set in the invention
below the upper limit (8 MPa or less), thereby it is easier to
obtain excellent film in thickness accuracy. When the film is
elongated along monoaxis in crosswise direction, for the purpose of
the improvement of film's mechanical properties or the like, giving
small elongation of 1.05 times or more and 1.8 times or less in the
longitudinal direction may be effective. And, the elongated film
is, if necessary, for the purpose of lowering the natural shrinkage
rate and improvement of heat shrinking properties, treated with
thermal-treatment and relaxation treatment at 50.degree. C. or more
and 100.degree. C. or less. Then, the film is quickly cooled before
the molecular orientation is loosening up, so as to obtain the
heat-shrinkable laminated film.
[0124] For the use of shrinkage in two directions such as for
overlapping, elongation magnification, in the longitudinal
direction, is twice or more, preferably 3 times or more, and the
upper limit is 10 times or less, preferably 6 times or less. In the
crosswise direction, it is twice or more, preferably 3 times or
more, and the upper limit is 10 times or less, preferably 6 times
or less. While, for the use of shrinkage in one direction such as
shrinkable labels, the magnification is twice or more and 10 times
or less, preferably 4 times or more and 8 times or less in the main
shrinking direction. Also, in the direction perpendicular to the
main shrinking direction, it is same size or more and twice or less
(same size means a film which is not elongated.), preferably 1.1
times or more and 1.5 times or less. Substantially, it is desirable
to determine a certain magnification within the range of monoaxial
elongation. In a film of biaxial elongation elongated within the
above elongation magnification, heat shrinkage ratio thereof in the
direction perpendicular to the main shrinking direction does not
become too large. For example, when the film is used as
heat-shrinkable label, it is possible to inhibit the so-called
"longitudinal sink mark" phenomenon wherein the film is thermally
shrink even in the container height direction when fitted to the
bottle. Thus, such a film is preferable.
[0125] Thickness of the film of the invention is not particularly
limited. It is normally 20 .mu.m or more, preferably 30 .mu.m or
more, and 80 .mu.m or less, preferably 70 .mu.m or less. When the
thickness is 20 .mu.m or more, film's handling property is
excellent; while, when it is 80 .mu.m or less, the film exhibits
excellent transparency and shrink processing, but also it is
economically preferable. Further, if necessary, surface treatment
or surface process such as corona discharge treatment, printing,
coating, and vapor deposition, moreover, bag-making process by
various solvent and heat seal, perforation process can be made.
[0126] The film of the invention is shaped from flat shape into
cylindrical shape and so on with the object to be covered by the
film for packaging. To make cylindrical containers for such as PET
bottles when requires to have printing thereon, necessary images
are printed on entire surface of the wide-width flat film winded by
a roll, then, the printed film is cut into a film having required
width and folded so as to make the printed surface become inner
surface of the film, finally center seal (shape of seal portion is
the so-called "envelop seams") is provided to complete the
cylindrical shape. As a method of center sealing, there may be a
method of adhesive bonding by organic solvent, a method by heat
seal, a method by adhesive, and a method by impulse sealer. Among
these, from the view point of productivity and pleasing appearance,
a method of adhesive bonding by organic solvent is suitably
used.
[0127] [A Molded Product, a Heat-Shrinkable Label, and a
Container]
[0128] Since the film of the invention exhibits excellent
low-temperature shrinkage, shrink finishing quality, transparency,
natural shrinkage and so on, its usage is not particularly limited.
If necessary, by forming printed layer, deposited layer and other
functional layers, various molded products such as bottles (blown
bottles), trays, lunch boxes, containers for food of delicatessen,
containers for dairy products. Especially, when the film of the
invention is used as heat-shrinkable labels for food containers
(for instance, PET bottles for soft drinks or food, glass bottles,
preferably PET bottles), the film is capable to adhere to the
complex shapes (e.g., cylindrical column, quadrangular prism,
pentagonal prism, and hexagonal column respectively having corners,
etc.), thus containers being fitted with labels of pleasing
appearance without having wrinkles and pocks can be obtained. The
molded products and containers of the invention can be produced by
using normal molding method.
[0129] The film of the invention exhibits excellent low-temperature
shrinkage and shrink finishing quality. It is used as
heat-shrinkable label material for plastic molded products being
deformed by beating at high temperatures, but also it is used as
heat-shrinkable label material for packaging (containers) using
materials as constituent thereof, whose thermal expansion and water
absorption rate are extremely different from that of the
heat-shrinkable film of the invention, for example at least one
kind of material selected from a group consisting of: metal,
porcelain, glass, paper, polyolefin series resin such as
polyethylene, polypropylene, and polybutene; polymethacrylate
series resin; polycarbonate series resin; polyester series resin
such as polyethylene terephthalate and polybutylene terephthalate;
and polyamide series resin, are used as the constituting
materials.
[0130] Examples of materials constituting plastic packaging to
which the film of the invention can be applicable include not only
the above resins, but also polystyrene, rubber-modified high-impact
polystyrene (HIPS), styrene butyl acrylate copolymer,
styrene-acrylonitrile copolymer, styrene-maleic anhydride
copolymer, acrylonitrile-butadien-styrene copolymer (ABS),
methacrylate ester-butadien-styrene copolymer (MBS), polyvinyl
chloride series resin, phenol resin, urea resin, melamine resin,
epoxy resin, unsaturated polyester resin, silicone resin. These
plastic packaging may be a mixture of two or more kinds of resins
or lamination thereof.
EXAMPLES
[0131] The present invention will be described with examples as
follows. Measurement values and evaluation criteria thereof shown
in the examples are defined as follows. Here, a take-over (flow)
direction of the laminated film is called as MD (Machine
Direction), and a direction perpendicular to the MD is called as TO
(Transverse Direction).
[0132] (1) Elongation Modulus
[0133] Elongation modulus was measured in a direction (MD)
perpendicular to the film's main shrinking direction at 23.degree.
C. in accordance with JIS K7127. Results evaluated in line with the
following criteria also shown in the tables.
[0134] .circleincircle.: elongation modulus is 1400 MPa or
more;
[0135] .largecircle.: elongation modulus is 1200 MPa or more and
below 1400 MPa;
[0136] and
[0137] x: elongation modulus is below 1200 MPa.
[0138] (2) Heat Shrinkage Ratio
[0139] A film was cut into pieces each having a size of 10 mm in MD
and 100 mm in TD, and the pieces were respectively soaked in
70.degree. C., 80.degree. C., and 90.degree. C. hot-water bath for
10 seconds, then the amount of shrinkage was measured. Heat
shrinkage ratio is defined by that a ratio of the shrinkage amount
to the original dimension before shrinkage in the film's main
shrinking direction (TD) and the ratio is shown in % value.
[0140] (3) Natural Shrinkage Ratio
[0141] A film was cut into pieces each having a size of 50 mm in MD
and 100 mm in TD, and left them in thermostatic bath under an
atmosphere at 30.degree. C. for 30 days. Then, the shrinkage amount
to the original dimension before shrinkage in the film's main
shrinking direction (TO) was measured, and the ratio is shown in %
value.
[0142] (4) Haze
[0143] Haze of the film was measured with a film of 50 go in
thickness in accordance with JIS K7105.
[0144] (5) TD Rupture Elongation
[0145] TD rupture elongation was measured in the film's main
shrinking direction (TD) under the condition at 23.degree. C.,
testing rate 200 mm/min in accordance with JIS K7127. At the time,
20 test pieces were tested, and average value thereof was defined
as the TD rupture elongation.
[0146] (6) MD Low-Temperature Rupture Elongation
[0147] MD low-temperature rupture elongation was measured in the
direction (MD) perpendicular to the film's main shrinking direction
under the condition at -5.degree. C., testing rate 200 nm/min in
accordance with JIS K7127. At the time, 20 test pieces were tested,
and average value thereof was defined as the ML low-temperature
rupture elongation.
[0148] (7) Low-Temperature Rupture Elongation Over Time
[0149] After 30 days incubation in the thermostatic bath under an
atmosphere at 30.degree. C., low-temperature rupture elongation of
the film was measured in the direction (MD) perpendicular to the
film's main shrinking direction under the condition at -5.degree.
C., testing rate 200 mm/min in accordance with JIS K7127. At the
time, 20 test pieces were tested, and average value thereof was
defined as the MD low-temperature rupture elongation.
[0150] (8) Tg of Resin for the Adhesive Layer (AD Layer)
[0151] Pellet of a material resin for the adhesive layer (AD layer)
was made into a sheet (thickness: 200 .mu.m) by heat stamping
machine under the condition at 200.degree. C., 10 MPa, for 10
minutes. After that, the sheet was cut into test pieces of size 4
mm.times.60 mm, and the respective test pieces were measured in the
longitudinal direction by using viscoelastic spectrometer DVA-200
(produced by IT Measurement Co., Ltd.) under the condition of
vibrational frequency 10 Hz, distortion 0.1%, and rate of
temperature increase 3.degree. C./min, distance between chucks 25
mm, from -150.degree. C. to 150.degree. C. From the obtained data,
a peak value of the loss elastic modulus (E'') was calculated; the
temperature of the peak value was defined as Tg.
[0152] (9) Seal Strength
[0153] At positions 10 mm inside from the both ends in TD of the
film, the both ends of the film were adhered each other with use of
tetrahydrofuran (THF) solvent so as to produce a cylindrical label.
The sealed portion was cut into the 15 mm width in the
circumference direction (TD), T-type peeling strength test with
individual cut pieces was conducted in the tensile testing machine
with thermostatic bath ("201X" produced by INTESCO, CO., Ltd) under
the condition of testing rate 200 mm/min in TD. Then, the testing
results were evaluated in line with the following criteria.
[0154] .circleincircle.: seal strength is 5N/15 mm width or
more;
[0155] .largecircle.: seal strength is 3N/15 mm width or more and
below 5N/15 mm width; and
[0156] x: seal strength is below 3N/15 mm width.
[0157] (10) Shrink Finishing Quality
[0158] A film on which grid network with 10 mm interval is printed
was cut into a size of 100 mm in MD.times.298 mm in TD. Portions of
10 mm at both ends in TD of the film were overlapped each other and
adhered by tetrahydrofuran (THF) solvent so as to produce a
cylindrical film. The cylindrical film was fitted with a
cylindrical PET bottle whose capacity is 1.5 L, it was come through
the steam-heating type shrinking tunnel of which length was 3.2 m
(3 zones) within about 4 seconds without rotation. The atmospheric
temperature in each zone of the tunnel was set within the range
from 70.degree. C. to 85.degree. C. by adjusting the steam flow
with flow control valve. After film coverage, shrink finishing
quality was evaluated in line with the following criteria.
[0159] .circleincircle.: shrinkage is sufficient and no wrinkle,
pock and distortion of the grid network is produced;
[0160] .largecircle.: shrinkage is sufficient, but wrinkles, pocks
and distortions of the grid network are slightly produced; and
[0161] x: shrinkage is sufficient, but wrinkles, pocks and
distortions of the grid network are remarkably produced.
[0162] (11) Haze of Recycled Film
[0163] The obtained heat-shrinkable film is pulverized by
pulverizer and made into recycled pellet. After that, a certain
amount of the pellet equivalent to 50 parts by mass to 100 parts by
mass of the film was added to the middle layer (M layer) so as to
obtain recycled films in a same manner as other individual
examples. With use of the obtained recycled films, haze was
measured in accordance with JIS K7105. Results were evaluated in
line with the following criteria also shown in the tables.
[0164] .circleincircle.: haze is below 5%;
[0165] .largecircle.: haze is 5% or more and below 10%; and
[0166] x: haze is 10% or more.
[0167] (12) Contents Overflow
[0168] A 500 mL PET bottle (a bottle for "Maro-cha 500 mL" produced
by Coca-Cola (Japan) Company, Limited was used.) was filled with
water to the height 5 mm below the mouth, a film made into a
cylindrical shape was made to cover the entire surface of the
bottle up the height of its neck portion, the bottle with the film
was come through the steam-heating type shrinking tunnel of which
length was 3.2 m (3 zones) within about 4 seconds without rotation.
After the film shrinkage with the tunnel, the contents overflow was
evaluated in line with the following criteria.
[0169] .largecircle.: almost no content overflow;
[0170] .DELTA.: sometimes content overflows; and
[0171] x: very frequently the content overflows.
[0172] (13) Evaluation of Heat Resistance of the Film
[0173] The obtained heat-shrinkable film is rolled around bottles,
and a plurality of the bottles is placed such that the outer
surface thereof (when antistatic agent was applied with the film,
the applied surface) contacts each other. These bottles were heated
by a heat seal tester "TP-701-A" produced by TESTER SANGYO CO.,
LTD. under 0.1 MPa pressure from 70.degree. C. to 120.degree. C. at
1.degree. C. interval and preserve the temperature for 1 minute at
each interval. After pressure-heating, test pieces were cut in to
the size of 1 mm.times.40 mm and peeled from the film ends, then
existence of fusion bonding on the film surface was observed. A
temperature just before fusion bonding of the film started was
checked, and the temperature of which all test pieces were not
fusion-bonded at N value=3 was defined as heat-fusion resistant
temperature. Also, results were evaluated in line with the
following criteria also shown in the tables.
[0174] .circleincircle.: test piece which fusion-bonds at
100.degree. C. or more;
[0175] .largecircle.: test piece which fusion-bonds at 90.degree.
C. or more and 100.degree. C. or less; and
[0176] x: test piece which fusion-bonds below 90.degree. C.
Example A-1
[0177] As shown in Table 1, as a polyester series resin composition
for the surface layer (S layer), a mixed resin composition having
100 parts by mass of PETG ("Copolyester6763" produced by Eastman
Chemical Company) (hereinafter, refer to "PETG".) and 10 parts by
mass of PBT (DURANEX 2002 produced by Polyplastics Co. r Ltd.,
Tg=45.degree. C., Tm=225.degree. C.) (hereinafter, refer to "PBT
1".) containing 0.05 mass % of amorphous silica of which average
particle diameter is 2.4 .mu.m ("Sylysia 320" produced by FUJI
SILYSIA CHEMICAL LTD.) was used. Also, as a styrene series resin
composition for the middle layer (M layer), a resin composition
containing 100 parts by mass of a mixed resin composition having 45
mass % of SBS (styrene/butadiene=90/10, storage elastic modulus
E'=2.5.times.10.sup.9 Pa, loss elastic modulus E'' peak
temperature-54.degree. C., Vicat Softening point=76.degree. C.,
hereinafter refer to "SBS1".) and 55 mass % of
SBS(styrene/butadiene=71/29, storage elastic modulus
E'=2.1.times.10.sup.8 Pa, loss elastic modulus E'' peak
temperature=-46.degree. C. and 84.degree. C., Vicat Softening
point-69.degree. C., hereinafter refer to "SBS2".), and 0.2 parts
by mass of antioxidant (commodity name: Smiriser GS produced by
Sumitomo Chemical Co., Ltd) was used. Further, as a copolymer of a
styrene series hydrocarbon and a conjugated dienic hydrocarbon for
the adhesive layer (AD layer), SIS (Clayton D1124 produced by JSR
Clayton Polymer Co., Ltd., styrene content ratio: 30 mass %,
Tg=-56.degree. C., hereinafter refer to "AD1".) was used. Materials
constituting each layer are fed into the respective biaxial
extruders produced by MITSUBISHI HEAVY INDUSTRIES, LTD. and
melt-mixed at the set temperature 240.degree. C., co-extrusion by
five-layer three-kind dies was conducted so as to have a film
thickness of each layer of the surface layer (S layer)/the adhesive
layer (AD layer)/the middle layer (M layer)/the adhesive layer (AD
layer)/the surface layer (S layer)=55 .mu.m/7 .mu.m/151 .mu.m/7
.mu.m/55 .mu.m. The laminated film was taken-over by castroll at
60.degree. C., was cooled and solidified so as to obtain
non-elongated laminated sheet of 300 m in width and 275 .mu.m in
thickness. Then, with use of film tentering machine produced by
KYOTO MACHINERY CO., LTD., the laminated film was elongated to 5.5
times in crosswise monoaxial direction at preheat temperature
100.degree. C., elongation temperature 85.degree. C. Later, thermal
treatment was carried out at 95.degree. C. for 6 seconds, and
finally the heat-shrinkable laminated film of thickness 50 .mu.m
was obtained.
[0178] Moreover, the obtained film was pulverized by pulverizer to
make recycled pellet, then 50 parts by mass thereof to 100 parts by
mass of the film was added to the middle layer (M layer), by
conducting the same manner as above, a recycled heat-shrinkable
laminated film was obtained. As the resin composition for the
middle layer (M layer) after recycling, to 100 parts by mass of
styrene series resin composition constituting the middle layer, the
resin composition constituting the surface layer (S layer) had 42
parts by mass and the resin composition constituting the adhesive
layer (AD layer) had 4 parts by mass.
[0179] An obtained film which had no problem to all the evaluation
items was marked as .largecircle., a film which had at least one
problem to the items was marked as x in the comprehensive
evaluation. The result is shown in Table 2.
Example A-2
[0180] As shown in Table 1, except for changing the content of PBT
1 used for the surface layer (S layer) to 15 parts by mass, and
changing the elongation temperature to 80.degree. C., Example A-2
was conducted in the same manner as Example A-1; a heat-shrinkable
laminated film and a recycled heat-shrinkable laminated film were
obtained. The evaluation results of these obtained films are shown
in Table 2.
Example A-3
[0181] As shown in Table 1, except for changing the mixed resin
composition consisting of PETG and PBT 1 used for the surface layer
(S layer) into PETG alone, and changing the thickness of
non-elongated laminated sheet to the surface layer (S layer)/the
adhesive layer (AD layer)/the middle layer (M layer)/the adhesive
layer (AD layer)/the surface layer (S layer)=69 .mu.m/7 .mu.m/123
.mu.m/7 .mu.m/69 .mu.m, Example A-3 was conducted in the same
manner as Example A-1; a heat-shrinkable laminated film and a
recycled heat-shrinkable laminated film were obtained. As the resin
composition for the middle layer (M layer) after recycling, to 100
parts by mass of styrene series resin composition constituting the
middle layer (M layer), the resin composition constituting the
surface layer (S layer) had 80 parts by mass and the resin
composition constituting the adhesive layer (AD layer) had 6 parts
by mass. The evaluation results of these obtained films are shown
in Table 2.
Example A-4
[0182] As shown in Table 1, except for changing the elongation
magnification in the crosswise monoaxial direction to 6.0 times,
Example A-4 was conducted in the same manner as Example A-1; a
heat-shrinkable laminated film and a recycled heat-shrinkable
laminated film were obtained. The evaluation results of these
obtained films are shown in Table 2.
Comparative Example A-1
[0183] As shown in Table 1, except for the lack of the adhesive
layer (AD layer) of Example A-1, and changing the composition of
the middle layer (M layer) from the mixed resin composition of SBS1
and SBS2 to PETG alone, Comparative Example A-1 was conducted in
the same manner as Example A-1; a heat-shrinkable laminated film
and a recycled heat-shrinkable laminated film were obtained. The
evaluation results of these obtained films are shown in Table
2.
Comparative Example A-2
[0184] As shown in Table 1, except for changing the elongation
magnification in crosswise monoaxial direction of Example A-1 to
7.5 times, Comparative Example A-2 was conducted in the same manner
as Example A-1; a heat-shrinkable laminated film and a recycled
heat-shrinkable laminated film were obtained. The evaluation
results of these obtained films are shown in Table 2.
Comparative Example A-3
[0185] As shown in Table 1, except for changing the thickness of
each layer of the non-elongated laminated sheet to the surface
layer (S layer)/the adhesive layer (AD layer)/the middle layer (M
layer)/the adhesive layer (AD layer)/the surface layer (S layer)=93
.mu.m/7 .mu.m/75 .mu.m/7 .mu.m/93 .mu.m, Comparative Example A-3
was conducted in the same manner as Example A-1; a heat-shrinkable
laminated film and a recycled heat-shrinkable laminated film were
obtained. The evaluation results of these obtained films are shown
in Table 2.
Comparative Example A-4
[0186] As shown in Table 1, except for changing the elongation
temperature of the elongation in crosswise monoaxial direction to
55.degree. C., Comparative Example A-4 was conducted in the same
manner as Example A-1. However, due to the f ilm breakage during
the film elongation, a heat-shrinkable laminated film elongated in
predetermined magnification could not be obtained.
Comparative Example A-5
[0187] As shown in Table 1, except for changing the temperature of
the elongation in crosswise monoaxial direction to 125.degree. C.,
Comparative Example A-5 was conducted in the same manner as Example
A-1. However, the film was weighed down with the weight of its own
and broken. Therefore the required heat-shrinkable laminated film
could not be obtained.
Comparative Example A-6
[0188] As shown in Table 1, except for changing AD1 used for the
adhesive layer (AD layer) to SBS (styrene content ratio 87 mass %,
Tg=36.degree. C.) (hereinafter, refer to "AD2".), Comparative
Example A-6 was conducted in the same manner as Example A-1; a
heat-shrinkable laminated film and a recycled heat-shrinkable
laminated film were obtained. The evaluation results of these
obtained films are shown in Table 2.
Comparative Example A-7
[0189] As shown in Table 1, except for changing the mass ratio of
the mixed resin composition consists of SBS1 and SBS2 used for the
middle layer (M layer) into the ratio such that SBS1 is 20 mass %
and SBS2 is 80 mass %, Comparative Example A-7 was conducted in the
same manner as Example A-1; a heat-shrinkable laminated film and a
recycled heat-shrinkable laminated film were obtained. The
evaluation results of these obtained films are shown in Table
2.
Comparative Example A-8
[0190] As shown in Table 1 except for changing AD1 used for the
adhesive layer (AD layer) to ethylene-acrylic acid copolymer (EAA)
("NOVATEC A500W" produced by Japan polyethylene Corporation,
content of acrylic acid (AA) 20 mass %) (hereinafter, refer to
"AD3".), Comparative Example A-8 was conducted in the same manner
as Example A-1; a heat-shrinkable laminated film and a recycled
heat-shrinkable laminated film were obtained. The evaluation
results of these obtained films are shown in Table 2.
TABLE-US-00001 TABLE 1 (Table 1) Example Comparative Example A-1
A-2 A-3 A-4 A-1 A-2 A-3 A-4 A-5 A-6 A-7 A-8 S layer PETG 100 100
100 100 100 100 100 100 100 100 100 100 (parts by mass) PBT 1 10 15
10 10 10 10 10 10 10 10 10 AD layer AD 1 100 100 100 100 -- 100 100
100 100 100 (parts by mass) AD 2 100 AD 3 100 M layer SBS 1 45 45
45 45 45 45 45 45 45 20 45 (mass %) SBS 2 55 55 55 55 55 55 55 55
55 80 55 PETG 100 S layer Thickness ratio (%) 40 40 50 40 40 40 75
40 40 40 40 40 Elongation temperature (.degree. C.) 85 80 85 85 85
85 85 55 125 85 85 85 Elongation Magnifications 5.5 5.5 5.5 6.0 5.5
7.5 5.5 5.5 5.5 5.5 5.5 5.5
[0191] TABLE-US-00002 TABLE 2 (Table 2) Example Comparative Example
A-1 A-2 A-3 A-4 A-1 A-2 A-3 A-4 A-5 A-6 A-7 A-8 Elongation modulus
1421 1460 1518 1438 2143 1515 1707 Unable Unable to 1373 1069 1454
(MPa) .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
to elongate .largecircle. X .circleincircle. Heat shrinkage
70.degree. C. 18 21 17 19 19 20 20 elongate due to the 20 24 17
ratio (%) 80.degree. C. 50 55 53 52 61 53 68 due to film 50 47 49
90.degree. C. 70 75 76 74 79 75 76 the film rupture 66 63 69
Natural shrinkage ratio (%) 0.9 1.1 0.8 0.9 0.7 0.9 0.7 rupture 1.0
0.8 0.8 Haze (%) 3.6 3.7 3.6 3.5 3.1 3.4 3.1 3.4 3.5 3.5 Haze of
4.8 4.6 4.4 4.8 4.3 4.5 5.1 3.9 4.3 12.4 recycled film
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. X Shrinking stress (MPa) 5.82 7.2 6.12 7.46 9.56
11.2 10.06 5.43 5.53 6.78 MD low-temperature 264 298 284 285 668
286 456 255 332 243 rupture elongation (%) Seal strength
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. X
.circleincircle. .largecircle. Shrink finishing quality
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
X X .largecircle. .circleincircle. .circleincircle.
.circleincircle. Contents overflow .largecircle. .largecircle.
.largecircle. .largecircle. X .DELTA. X .largecircle. .largecircle.
.largecircle. Comprehensive evaluation .largecircle. .largecircle.
.largecircle. .largecircle. X X X X X X X X
[0192] As seen from Tables 1 and 2, the films of Examples
A-1.about.A-4, which were constituted by layers produced so as to
be within the predetermined range of the invention, were
respectively excellent in all the evaluation items of shrink
finishing quality, peeling strength, transparency of the recycled
film, and contents overflow compared with those properties of
Comparative Examples A-1.about.A-8.
[0193] On the other hand, the film of Comparative Example A-1
constituted by polyester series resin composition only, the film of
Comparative Example A-2 elongated in the outer range from the range
predetermined by the invention, and the film of Comparative Example
A-3 constituted by laminated films in the outer range from the
lamination ratio predetermined by the invention, all had large
shrinking stress, and lacked in shrink finishing quality. In
addition, the films of Comparative Examples A-4 and A-5 elongated
at a temperature in the outer range from the range predetermined by
the invention had difficulties with elongation at the required
magnification. Further, the films of Comparative Example A-6 and
A-8 using resins, for the adhesive layer (AD layer), other than the
resin composition that is predetermined by the invention did not
exhibit sufficient sealing strength thereby transparency of the
recycled film was remarkably deteriorated.
[0194] Accordingly, it is understood that the heat-shrinkable
laminated film of the invention exhibits excellent film rigidity,
small natural shrinkage, transparency of the recycled film, and
reduction of mechanical strength over time, with suppressed film
interlayer peeling and shrinking stress, and the film is applicable
to shrinkable packing, shrinkable bond-packing, shrinkable label
and the like.
Example B-1
[0195] As shown in Table 3, as a resin composition of the surface
layer (S layer), a mixed resin composition comprising as an
amorphous polyester series resin 100 parts by mass of polyester
resin copolymer (hereinafter, refer to "PET1".) having terephthalic
acid residue as dicarboxylic acid residue and 68 mole % of ethylene
glycol residue and 32 mole % 1,4-cyclohexane dimethanol residue as
diol residue, and as a crystalline polyester series resin 30 parts
by mass of polyester resin (hereinafter, refer to "PBT2".) having
terephthalic acid residue as dicarboxylic acid residue and
1,4-butanediol residue as diol residue, were used. Also, as styrene
resin of the middle layer (M layer), a resin composition containing
100 parts by mass of mixed resin composition having 45 mass % of
SBS1 and 55 mass % of SBS2, and 0.2 parts by mass of antioxidant
(commodity name: Smiriser GS produced by Sumitomo Chemical Co.,
Ltd) to 100 parts by mass of the above composition, was used.
Moreover, as a styrene series hydrocarbon and a conjugated dienic
hydrocarbon or derivatives thereof for the adhesive layer (AD
layer), AD1 was used. Materials constituting each layer are fed
into the respective biaxial extruders produced by MITSUBISHI HEAVY
INDUSTRIES, LTD. and melt-mixed at the set temperature 240.degree.
C. Then, co-extrusion from five-layer three-kind dies was conducted
so as to have a film having thickness of each layer: the surface
layer (S layer)/the adhesive layer (AD layer)/the middle layer (M
layer)/the adhesive layer (AD layer)/the surface layer (S layer)=55
.mu.m/7 .mu.m/151 .mu.m/7 .mu.m/55 .mu.m. The laminated film was
taken-over by castroll at 60.degree. C., was cooled and solidified
so as to obtain non-elongated laminated sheet of 300 m in width and
275 .mu.m in thickness. Then, with use of film tenter facility
produced by KYOTO MACHINERY CO., LTD., the laminated film was
elongated to 5.5 times in crosswise monoaxial direction at preheat
temperature 105.degree. C. and elongation temperature 90.degree. C.
Later, the elongated film was quickly cooled and finally the
heat-shrinkable laminated film of thickness 50 .mu.m was
obtained.
[0196] Moreover, the obtained film was pulverized by pulverizer to
make recycled pellet, then 50 parts by mass thereof to 100 parts by
mass of the film was reproductively added to the middle layer (M
layer), by conducting the same manner as above, a recycled
heat-shrinkable laminated film was obtained. As the resin
composition for the middle layer (M layer) at the time of addition
of a reclamation material, to 100 parts by mass of styrene series
resin composition constituting the middle layer, the resin
composition constituting the surface layer (S layer) had 42 parts
by mass and the resin composition constituting the adhesive layer
(AD layer) had 4 parts by mass.
[0197] The evaluated results are shown in Table 4. In the table, an
obtained film which had no problem to all the evaluation items was
marked as .largecircle., a film which had at least one problem to
the items was marked as x in the comprehensive evaluation.
Example B-2
[0198] As shown in Table 3, except for changing the content of PBT2
used for the surface layer (S layer) to 10 parts by mass, Example
B-2 was conducted in the same manner as Example B-1; a
heat-shrinkable laminated film and a recycled heat-shrinkable
laminated film were obtained. The evaluation result of these
obtained films is shown in Table 4
Example B-3
[0199] As shown in Table 3, except for changing AD1 used for the
adhesive layer (AD layer) to styrene-isoprene copolymer ("Hybrar"
produced by KURARAY CO., LTD., styrene content 20 mass %, Tg=-14%
C, hereinafter, refer to "AD4".), Example B-3 was conducted in the
same manner as Example B-1; a heat-shrinkable laminated film and a
recycled heat-shrinkable laminated film were obtained. The
evaluation results of these obtained films are shown in Table
4.
Example B-4
[0200] As shown in Table 3, except for changing PBT2 used for the
middle layer (M layer) into 30 parts by mass of copolymeric
polybutylene terephthalate resin (hereinafter, refer to "PBT3".)
having 90 mole % of terephthalic acid residue and 10 mole % of
isophthalic acid residue as dicarboxylic acid residue together with
1,4-butanediol residue as diol residue, Example B-4 was conducted
in the same manner as Example B-1; a heat-shrinkable laminated film
and a recycled heat-shrinkable laminated film were obtained. The
evaluation results of these obtained films are shown in Table
4.
Example B-5
[0201] As shown in Table 3, except for changing PBT2 used for the
middle layer (M layer) into 20 parts by mass of copolymeric
polybutylene terephthalate resin (hereinafter, refer to "PBT3".)
having 89 mole % of terephthalic acid residue and 11 mole % of
isophthalic acid residue as dicarboxylic acid residue together with
ethylene glycol residue as diol residue, Example B-5 was conducted
in the same manner as Example B-1; a heat-shrinkable laminated film
and a recycled heat-shrinkable laminated film were obtained. The
evaluation results of these obtained films are shown in Table
4.
Example B-6
[0202] As shown in Table 3, except for changing the content of PBT2
used for the surface layer (S layer) to 20 parts by mass of
polytrimethylene terephthalate (hereinafter, refer to "PTT"),
Example B-6 was conducted in the same manner as Example B-5; a
heat-shrinkable laminated film and a recycled heat-shrinkable
laminated film were obtained. The evaluation results of these
obtained films are shown in Table 4.
Example B-7
[0203] As shown in Table 3, in Example B-1, in order to form a heat
resistant layer on the surface layer (S layer), aqueous solution of
"ANSTECKS C200X" produced by TOHO Chemical Industry Co., LTD.
(cationic surfactant, 50% concentration of the surfactant,
hereinafter, refer to "SAA1".) was applied onto the pre-elongated
sheet with use of kiss-system roll coater. Later, film elongation
was carried out in the same manner as Example B-1, and the heat
resistant layer containing 0.0006 g/m.sup.2 SAA1 on the surface
layer (S layer) was provided. The evaluation results of obtained
heat-shrinkable laminated film and the recycled heat-shrinkable
laminated film are shown in Table 4.
Example B-8
[0204] As shown in Table 3, except for changing the heat resistant
layer to a heat resistant layer containing 0.006 g/m.sup.2 SAA1,
Example B-8 was conducted in the same manner as Example B-7; a
heat-shrinkable laminated film and a recycled heat-shrinkable
laminated film were obtained. The evaluation results of these
obtained films are shown in Table 4.
Example B-9
[0205] As shown in Table 3, in Example B-4, in order to form a heat
resistant layer on the surface layer (S layer), SAA1 was applied
onto the pre-elongated sheet with use of kiss-system roll coater.
Later, film elongation was carried out in the same manner as
Example B-4, and the heat resistant layer containing 0.015
g/m.sup.2 SAA1 on the surface layer (S layer) was provided. The
evaluation results of obtained heat-shrinkable laminated film and
the recycled heat-shrinkable laminated film are shown in Table
4.
Example B-10
[0206] As shown in Table 3, in Example B-2, in order to form a heat
resistant layer on the surface layer (S layer), aqueous solution of
"ELECTROSTRIPPER AC" produced by KAO Corporation (cationic
surfactant, 9.9% concentration of the surfactant, hereinafter,
refer to "SAA2".) was applied onto the pre-elongated sheet with use
of kiss-system roll coater. Later, film elongation was carried out
in the same manner as Example B-2, and the heat resistant layer
containing 0.015 g/m.sup.2 SAA2 on the surface layer (S layer) was
provided. The evaluation results of obtained heat-shrinkable
laminated film and the recycled heat-shrinkable laminated film are
shown in Table 4.
Example B-11
[0207] As shown in Table 3, in Example B-10, except for changing
the heat resistant layer to a heat resistant layer containing
0.0045 g/m.sup.2 of SAA2, a heat resistant layer was formed in the
same manner as Example B-10; a heat-shrinkable laminated film and a
recycled heat-shrinkable laminated film were obtained. The
evaluation results of these obtained films are shown in Table
4.
Comparative Example B-1
[0208] As shown in Table 3, except for changing the mixed resin
composition for the used of the surface layer (S layer) consisting
of PET1 and PBT2 to a mixed resin composition having 100 parts by
mass of PET1 and 30 parts by mass of PBT3, not having the adhesive
layer (AD layer), and changing the composition of the middle layer
(M layer) from the mixed resin composition of SBS1 and SBS2 to PET1
alone, further co-extruding from three layers two kinds dies was
conducted so as to make the thickness of the laminated sheet become
the surface layer (S layer)/the middle layer (N layer)/the surface
layer (S layer)=100 .mu.m/75 .mu.m/100 .mu.m, Comparative Example
B-1 was conducted in the same manner as Example B-1. Thus, a
heat-shrinkable laminated film and a recycled heat-shrinkable
laminated film were obtained. The evaluation results of these
obtained films are shown in Table 4.
Reference Example 1
[0209] As shown in Table 3, except for the resin composition used
for the surface layer (S layer) consisting of PET1 and PBT2 to PET1
alone, Reference Example 1 was conducted in the same manner as
Example B-1. Thus, a heat-shrinkable laminated film and a recycled
heat-shrinkable laminated film were obtained. The evaluation
results of these obtained films are shown in Table 4.
Reference Example 2
[0210] As shown in Table 3, except for changing mass ratio of the
mixed resin composition used for the surface layer (S layer)
consisting of PET1 and PBT2 into 50 parts by mass of PBT2 to 100
parts by mass of PET1, Reference Example 2 was conducted in the
same manner as Example B-1. Thus, a heat-shrinkable laminated film
and a recycled heat-shrinkable laminated film were obtained. The
evaluation results of these obtained films are shown in Table
4.
Comparative Example B-2
[0211] As shown in Table 3, except for changing AD1 used for the
adhesive layer (AD layer) to AD3, Comparative Example B-2 was
conducted in the same manner as Example B-1. Thus, a
heat-shrinkable laminated film and a recycled heat-shrinkable
laminated film were obtained. The evaluation results of these
obtained films are shown in Table 4 TABLE-US-00003 TABLE 3 (Table
3) Example B-1 B-2 B-3 B-4 B-5 B-6 B-7 B-8 B-9 S layer Amorphous
polyester PET 1 100 100 100 100 100 100 100 100 100 (parts by mass)
series resin Crystalline PET 2 20 polyester series PBT 2 30 10 30
30 30 resin PBT 3 30 30 PTT 20 AD layer Styrene- AD 1 100 100 100
100 100 100 100 100 (parts by mass) conjugated dien AD 4 100
copolymer AD 3 M layer Styrene series SBS 1 45 35 45 45 45 45 45 45
45 (mass %) resin composition SBS 2 55 65 55 55 55 55 55 55 55 PET
1 Heat resistant -- SAA 1 0.0006 0.0060 0.0015 layer (g/m.sup.2)
SAA 2 Comparative Reference Comparative Example Example Example
Example B-10 B-11 B-1 1 2 B-2 S layer Amorphous polyester PET 1 100
100 100 100 100 100 (parts by mass) series resin Crystalline PET 2
polyester series PBT 2 10 10 50 30 resin PBT 3 30 PTT AD layer
Styrene- AD 1 100 100 -- 100 100 (parts by mass) conjugated dien AD
4 copolymer AD 3 100 M layer Styrene series SBS 1 35 35 45 45 45
(mass %) resin composition SBS 2 65 65 55 55 55 PET 1 100 Heat
resistant -- SAA 1 layer (g/m.sup.2) SAA 2 0.0015 0.0045
[0212] TABLE-US-00004 TABLE 4 (Table 4) Example B-1 B-2 B-3 B-4 B-5
B-6 B-7 B-8 B-9 Elongation modulus 1421 1460 1438 1537 1443 1531
1434 1444 1540 (MPa) .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. Heat shrinkage
70.degree. C. 17.5 15.7 16.8 17.3 15.3 16.2 17.2 17.0 17.5 ratio
(%) 80.degree. C. 38.2 47.5 37.5 36.2 42.1 43.3 38.5 38.7 36.5
90.degree. C. 58.1 65.7 55.7 53.2 57.2 59.4 58.0 59.0 53.5 Natural
shrinkage ratio (%) 0.9 1.1 0.8 0.8 1.0 1.0 0.9 0.9 0.9 Haze (%)
3.6 3.7 3.6 3.8 3.4 3.2 3.6 3.6 3.8 TD rupture elongation (%) 60 47
53 45 56 63 58 55 50 MD low-temperature rupture 264 298 271 274 321
292 268 280 270 elongation (%) Low-temperature rupture 240 252 201
221 284 276 250 240 235 elongation over time Tg of resin for the
Adhesive -56 -56 -8 -56 -56 -56 -56 -56 -56 layer (.degree. C.)
Seal strength .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. Shrink finishing quality
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. Haze of 4.8 4.6 6.2 4.6 4.7 4.7 4.8 4.8 4.6
recycled film .circleincircle. .circleincircle. .largecircle.
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
.circleincircle. .circleincircle. Fusion resistant temperature 94
90 95 92 91 90 110 120 109 of the film (.degree. C.) .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .circleincircle. .circleincircle. .circleincircle.
Comprehensive evaluation .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Comparative Reference Comparative
Example Example Example Example B-10 B-11 B-1 1 2 B-2 Elongation
modulus 1455 1450 2143 1398 1507 1444 (MPa) .circleincircle.
.circleincircle. .circleincircle. .largecircle. .circleincircle.
.circleincircle. Heat shrinkage 70.degree. C. 15.1 15.0 16.3 14.2
17.2 16.9 ratio (%) 80.degree. C. 47.0 46.5 50.1 48.5 25.3 37.6
90.degree. C. 66.0 66.2 62.1 67.4 37.4 56.2 Natural shrinkage ratio
(%) 1.1 1.1 0.7 1.1 0.9 0.8 Haze (%) 3.6 3.6 3.1 3.7 3.4 3.5 TD
rupture elongation (%) 48 48 65 35 64 58 MD low-temperature rupture
274 270 763 298 56 243 elongation (%) Low-temperature rupture 235
255 42 252 8 217 elongation over time Tg of resin for the Adhesive
-56 -56 -- -56 -56 37 layer (.degree. C.) Seal strength
.circleincircle. .circleincircle. .circleincircle. .circleincircle.
X .largecircle. Shrink finishing quality .circleincircle.
.circleincircle. X .circleincircle. X .largecircle. Haze of 4.7 4.7
4.3 4.6 3.8 10.4 recycled film .circleincircle. .circleincircle.
.circleincircle. .circleincircle. .circleincircle. X Fusion
resistant temperature 115 120 93 74 95 92 of the film (.degree. C.)
.circleincircle. .circleincircle. .largecircle. X .largecircle.
.largecircle. Comprehensive evaluation .largecircle. .largecircle.
X X X X
[0213] According to Tables 3 and 4, all the films of Examples
B-1.about.B-6 constituted by layers made within the predetermined
range of the invention were superior in shrink finishing quality,
mechanical strength over time, TD rupture elongation, seal
strength, and transparency of the recycled film to that of
Comparative Examples B-1.about.B-2. Moreover, films of Examples
B-7.about.B-11 of which surface layers were provided with heat
resistant layers exhibited excellent heat resistance. On the other
hand, the film of Comparative Example B-1 constituted by polyester
resin composition alone had remarkable decline of shrink finishing
quality and mechanical strength over time. In addition, the film of
Reference Example 1 which did not contain crystalline polyester
resin in the surface layer (S layer) slightly lacked of TD rupture
elongation strength. Further, the film of Reference Example 2
contained more crystalline polyester resin in the surface layer (S
layer) than that of the predetermined range of the invention had
lack of shrunk property; thereby shrink finishing quality thereof
was slightly inferior to the Examples of the invention.
Furthermore, the films of Comparative Examples B-2 using resins
other than the resin composition determined in the invention for
the adhesive layer (AD layer) had remarkable deterioration in
transparency.
[0214] Consequently, it is understood that a film of the invention
exhibits excellent film rigidity, transparency at a time of
recycling, and small natural shrinkage, with suppressed film
interlayer peeling and shrinking stress, and is applicable to
shrinkable packing, shrinkable bond-packing, shrinkable label and
the like.
INDUSTRIAL APPLICABILITY
[0215] A film of the present invention exhibits excellent film
rigidity, transparency of the recycled film, and small natural
shrinkage, with suppressed film interlayer peeling and shrinking
stress, and is applicable to shrinkable packing, shrinkable
bond-packing, shrinkable label and the like. Therefore, it can be
used for various molded products such as bottles (blown bottles),
trays, lunch boxes, containers for food of delicatessen, containers
for dairy products, especially it can be used as a heat-shrinkable
label.
* * * * *