JP2002215044A - Polyolefinic heat shrinkable label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyolefinic heat shrinkable label having excellent low temperature shrinkability. SOLUTION: The base film of the polyolefinic heat shrinkable label provided with a printing layer on at least one surface of the base film comprises a front surface layer consisting of a non-crystalline cyclic polyolefinic polymer having a glass transition temperature (Tg) ranging from 60 to 150 deg.C and a central layer consisting of a propylene-base random copolymer obtained by copolymerization with a metallocene catalyst. The thermal shrinkage rate in a main orientation direction X when the base film is immersed for 10 seconds into hot water of 80 deg.C may preferably be 25 to 50%. The propylene-base random copolymer is preferably an ethylene-propylene-base random copolymer. The ratio of the ethylene component in the ethylene-propylene-base random copolymer may be 3 to 4.5 wt.% of the total amount of the monomer component of the copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyolefin-based heat-shrinkable label having excellent low-temperature shrinkage and heat resistance.

[0002]

2. Description of the Related Art Hitherto, as a heat-shrinkable label to be mounted on a container such as a polyethylene terephthalate bottle (PET bottle), a label using a base film made of a polyvinyl chloride polymer has been used. However, labels with a base film made of a polyvinyl chloride polymer have the problem of generating toxic gases and dioxins when incinerated after disposal, and in recent years the use of polyolefin-based heat-shrinkable labels has been studied. I have.

However, conventional polyolefin-based heat-shrinkable labels have low low-temperature shrinkage and high shrinkage temperatures (for example, 10
(0 ° C. or higher), it is difficult to use when the PET bottle is deformed or the content is easily deteriorated by heating. In addition, when contracted at a low temperature (for example, about 80 ° C.), the appearance characteristics may be deteriorated. In addition, the impact resistance is low, and may not be sufficient. Furthermore, polystyrene-based resins have been used as labels having excellent low-temperature shrinkability,
Heat resistance (for example, label strength and label appearance when used in a hot bender (heated / heated vending machine)) is not sufficient.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a polyolefin-based heat-shrinkable label having excellent low-temperature shrinkability. Another object of the present invention is to provide a polyolefin-based heat-shrinkable label having excellent heat resistance. Still another object of the present invention is to provide a polyolefin-based heat-shrinkable label having excellent impact resistance.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that a base film is made of a surface layer made of a specific olefin-based polymer and propylene prepared using a specific catalyst. The present inventors have found that a polyolefin-based heat-shrinkable label excellent in low-temperature shrinkage and heat resistance can be obtained when the heat-shrinkable label is constituted with a center layer made of a polymer.

That is, the present invention is a heat-shrinkable label having a printing layer provided on at least one surface of a base film, wherein the base film has a glass transition temperature (T
g) having a surface layer composed of an amorphous cyclic olefin polymer having a temperature in the range of 60 to 150 ° C., and a central layer composed of a propylene random copolymer obtained by copolymerization with a metallocene catalyst. A polyolefin-based heat-shrinkable label.

[0007] The base film is placed in hot water at 80 ° C.
The thermal shrinkage in the main orientation direction X when immersed for 0 second may be 25 to 50%.

In the present invention, the propylene random copolymer is preferably an ethylene-propylene random copolymer.

In a preferred embodiment of the present invention, the proportion of the ethylene component in the ethylene-propylene random copolymer is 3 to 4.5 with respect to the total amount of the monomer components of the copolymer.
% By weight. Further, the melting point of the ethylene-propylene random copolymer is preferably from 120 to 130 ° C.

The amorphous cyclic olefin polymer includes:
A ring-opened polymer of a cyclic olefin or a hydrogenated product thereof is preferred. The printing layer may be formed of a reactive urethane ink.

The heat-shrinkable polyolefin label of the present invention is preferably formed in a cylindrical shape such that the direction X is the circumferential direction.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings as necessary. FIG. 1 is a schematic sectional view showing an example of the polyolefin-based heat-shrinkable label of the present invention.

In the example shown in FIG. 1, the heat-shrinkable label 1 includes a base film 2 and a printing layer 3 provided on one surface of the base film 2. Base film 2
Is composed of a central layer 4 and surface layers 5 and 5 provided on both sides of the central layer 4. The surface layers 5 and 5 (hereinafter sometimes simply referred to as “surface layer 5”) are in contact with the outer layer, which is a layer not in contact with the adherend (substrate), and the adherend. And the inner layer which is the layer on the side (the layer on the printing layer 3 side).

(Center Layer) The center layer 4 is formed of a uniaxial or biaxially oriented film made of a propylene-based random copolymer obtained by copolymerization using a metallocene catalyst.

In the present invention, a propylene-based random copolymer is produced by using a metallocene catalyst as a catalyst and propylene and a monomer component having copolymerizability with respect to the propylene (hereinafter simply referred to as “copolymerizable monomer”). (Sometimes referred to as "component"). As the copolymerizable monomer component, α-olefins other than propylene (for example, ethylene, butene-1, pentene-1, hexene-1, 4-methyl-1-pentene,
An α-olefin having 2 or 4 to 20 carbon atoms such as octene-1) is preferably used. As the copolymerizable monomer component, ethylene is optimal. The copolymerizable monomer components can be used alone or in combination of two or more.

The propylene-based random copolymer is a copolymer containing propylene as a constituent monomer, and includes, for example, an ethylene-propylene random copolymer. In this ethylene-propylene random copolymer, the ratio of ethylene to propylene is, for example, the former / the latter (weight ratio) = 2/98 to 5/95 (preferably 3/9).
7 to 4.5 / 95.5). That is, the proportion of the ethylene component in the ethylene-propylene random copolymer is, for example, 2 to 5% by weight (preferably 3 to 4.5) based on the total amount of the monomer components.
% By weight).

As the ethylene-propylene random copolymer, those having a melting point in the range of 115 to 140 ° C. can be used. As the ethylene-propylene random copolymer, those having a melting point of 130 ° C. or lower (for example, 120 to 130 ° C., preferably 120 to 125 ° C.) are most suitable for enhancing low-temperature shrinkage. In addition, the melting point is 120
C. or more (e.g., 120 to 140 C., preferably 125
-140 ° C), a material having excellent heat resistance can be obtained.

In the present invention, the propylene random copolymer preferably has an isotactic index of 90% or more from the viewpoints of low-temperature shrinkage and film stiffness.

By using, as the central layer, a uniaxially or biaxially oriented film made of a propylene-based random copolymer obtained by copolymerization using a metallocene catalyst, the low-temperature shrinkage can be further improved. In addition, the propylene-based random copolymer with a metallocene catalyst has a higher maximum shrinkage value at the same temperature than the propylene-based random copolymer with a non-metallocene catalyst, and fits into a container during heat shrinkage. Can be enhanced. Furthermore, since the molecular weight distribution is narrow and the proportion of low molecular components is small, the impact resistance is further improved, and even if the film is substantially uniaxially stretched in the transverse direction suitable as a heat-shrinkable label, In the printing step, the bag making step, and the label attachment of the heat-shrinkable label by the labeler, it is possible to prevent the tearing in the horizontal direction due to the tension or impact applied in the vertical direction.

As the metallocene catalyst, a conventional metallocene catalyst for olefin polymerization can be used. Specifically, the following catalyst component (a) and catalyst component (b)
And, if necessary, the catalyst component (c) can be suitably used.

The catalyst component (a) is a metallocene transition metal complex. The metallocene-based transition metal complexes can be used alone or in combination of two or more.

As the metallocene transition metal complex, a metallocene transition metal complex represented by the following formula (1) can be suitably used. Q ¹ L ¹ L ² MeX ¹ X ² (1) (In the formula (1), Me represents a zirconium atom, a titanium atom or a hafnium atom. L ¹ and L ² are the same or different and are each conjugated to Me Q ¹ represents a bonding group bridging two conjugated five-membered ring ligands, and X ¹ and X ² are the same or different and each represent
A hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkylamide group having 1 to 20 carbon atoms, a trifluoromethanesulfonic acid group,
A phosphorus atom-containing hydrocarbon group having 1 to 20 carbon atoms or 1 carbon atom
And represents a silicon atom-containing hydrocarbon group of -20. )

In the formula (1), Me is a zirconium atom, a titanium atom or a hafnium atom, and a zirconium atom is preferred. Note that Me may be a tetravalent transition metal atom such as a nickel atom, a palladium atom, and a platinum atom.

L ¹ and L ² are each a conjugated five-membered ring ligand for Me. L ¹ and L ² may be the same or different. The two conjugated five-membered ring ligands L ¹ and L ² are preferably asymmetric with respect to the plane containing Me from the viewpoint of the relative position via the Q ¹ group.

L ¹ and L ² are respectively (C ₅ H
_4-a R ¹ a), it can be represented by _{(C 5 H 4-b R} 2 b). R ¹ and R ² are the same or different and are each a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, an alkoxy group,
It represents a silicon-containing hydrocarbon group, a phosphorus-containing hydrocarbon group, a nitrogen-containing hydrocarbon group or a boron-containing hydrocarbon group. Further, two adjacent R ¹ or two R ² may be bonded to each other to form a ring. a and b are the same or different,
Each is a positive integer of 0 or 4 or less.

Specifically, the conjugated five-membered ring ligand as L ¹ and L ² is a ligand having a cyclopentadienyl skeleton, for example, a cyclopentadienyl group, a methylcyclopentadiene group. Substituted cyclopentadienyl groups such as enyl, dimethylcyclopentadienyl, trimethylcyclopentadienyl, tetramethylcyclopentadienyl, pentamethylcyclopentadienyl, methylethylcyclopentadienyl, hexylcyclopentadienyl, and indenyl Group, substituted indenyl group such as 2,4-dimethylindenyl, 2-methyl-4-phenylindenyl, 4,
Partial water additives of substituted indenyl groups such as 5,6,7-tetrahydroindenyl and fluorenyl groups are exemplified.

Q ¹ is a linking group bridging ^two conjugated five-membered ring ligands (L ¹ and L ² ). Examples of the bonding group represented by Q ¹ include a divalent hydrocarbon group having 1 to 20 carbon atoms and a silylene group having a hydrocarbon group having 1 to 20 carbon atoms. Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms for Q ¹ include divalent unsaturated hydrocarbon groups such as an alkylene group (eg, ethylene, isopropylidene, etc.) and a cycloalkylene group (eg, cyclohexylene, etc.). Hydrogen groups are included. Among them, a divalent hydrocarbon group having 1 to 6 carbon atoms is preferable. Examples of the silylene group having a hydrocarbon group having 1 to 20 carbon atoms include 1 to 12 carbon atoms such as dimethylsilylene.
Are preferred.

X ¹ and X ² may be the same or different. In X ¹ and X ² , the halogen atom includes, for example, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom (preferably a chlorine atom).

Specific examples of the metallocene transition metal complex are shown below. For example, as a metallocene-based transition metal complex in which a binding group bridging two conjugated five-membered ring ligands is an alkylene group, for example, ethylene-1,2-bis (1
-Indenyl) zirconium dichloride, ethylene-
1,2-bis {1- (4,5,6,7-tetrahydroindenyl)} zirconium dichloride, ethylene-1,
2-bis {1- (2,4-dimethylindenyl)} zirconium dichloride, ethylene-1,2-bis {1-
(2-methyl-4-phenylindenyl) {zirconium dichloride, ethylene-1,2-bis} 1- (2-methyl-4,5-benzoindenyl)} zirconium dichloride, ethylene-1,2-bis [ 1- {2-methyl-
4- (1-naphthyl) indenyl}] zirconium dichloride.

Examples of the metallocene transition metal complex in which the bonding group bridging two conjugated five-membered ring ligands is a silylene group include, for example, dimethylsilylenebis (1-indenyl) zirconium dichloride, dimethylsilylenebis}. 1- (4,5,6,7-tetrahydroindenyl)}
Zirconium dichloride, dimethylsilylene bis ｛1-
(2,4-dimethylindenyl) {zirconium dichloride, dimethylsilylenebis} 1- (2-methyl-4-)
Phenylindenyl) {zirconium dichloride, dimethylsilylene bis} 1- (2-methyl-4,5-benzoindenyl)} zirconium dichloride, dimethylsilylenebis [1- {2-methyl-4- (1-naphthyl) indenyl {} Zirconium dichloride, dimethylsilylenebis {1- (2-methyl-4-isopropylindenyl)} zirconium dichloride, dimethylsilylenebis {1- (2-methyl-4,6-diisopropylindenyl)} zirconium dichloride, dimethyl Silylene bis {1- (2-methylindenyl)} zirconium dichloride, methylphenylsilylene bis (1-indenyl)
Zirconium dichloride, methylphenylsilylenebis {1- (4,5,6,7-tetrahydroindenyl)}
Zirconium dichloride, methylphenylsilylenebis {1- (2,4-dimethylindenyl)} zirconium dichloride, methylphenylsilylenebis {1- (2-
Methyl-4-phenylindenyl) {zirconium dichloride, methylphenylsilylenebis} 1- (2-methyl-4,5-benzoindenyl)} zirconium dichloride, methylphenylsilylenebis [1- {2-methyl-4- (1-Naphthyl) indenyl}] zirconium dichloride, methylphenylsilylenebis {1- (2-methyl-4-isopropylindenyl)} zirconium dichloride, methylphenylsilylenebis {1- (2-methyl-4,6-diisopropyl) Indenyl) {zirconium dichloride, methylphenylsilylenebis} 1-
(2-methylindenyl) zirconium dichloride,
Dimethylsilylenebis {1- (2-methyl-4,5-benzoindenyl)} zirconium dimethyl, dimethylsilylenebis {1- (2-methyl-4,5-benzoindenyl)}] zirconium methyl chloride, dimethylsilylene Bis {1- (2-methyl-4-phenylindenyl)} zirconium dimethyl, dimethylsilylenebis {1- (2-methyl-4-phenylindenyl)} zirconium chlorodimethylamide, dimethylsilylenebis {1- (2 -Methyl-4-phenyl-hydroazulenyl) {zirconium dichloride, dimethylsilylenebis} 1- (2-methyl-4-phenyl-4,5,6,7,
8-pentahydroazulenyl)} zirconium dichloride, dimethylsilylenebis [1- {2-methyl-4-
(1-Naphthyl) -4-hydroazulenyl} zirconium dichloride, dimethylsilylene bis [1- {2-methyl-4- (1-naphthyl) -4,5,6,7,8-pentahydroazulenyl} zirconium Dichloride, methylphenylsilylenebis {1- (2-methyl-4-phenyl-4,5,6,7,8-pentahydroazulenyl)} zirconium dichloride, dimethylsilylenebis {1- (2-ethyl-4, 5-benzoindenyl) {zirconium dichloride, dimethylsilylenebis} 1-
(2-ethyl-4-phenylindenyl) {zirconium dichloride, dimethylsilylenebis} 1- (2-ethyl-4-phenyl-4-hydroazulenyl)} zirconium dichloride, dimethylsilylenebis {1- (2-ethyl-4) -Phenyl-4,5,6,7,8-pentahydroazulenyl) {zirconium dichloride, dimethylsilylene} 1- (2-ethyl-4-phenylindenyl)} 1- (2,3,5-trimethyl Cyclopentadienyl) {zirconium dichloride, dimethylsilylene} 1- (2-ethyl-4-phenyl-4,5,6,7,
8-pentahydroazulenyl) {1- (2,3,5-
Trimethylcyclopentadienyl) {zirconium dichloride, dimethylsilylenebis} 1- (2-methyl-
4,4-dimethyl-sila-4,5,6,7-tetrahydroindenyl) {zirconium dichloride, dimethylsilylene bis} 1- (2-ethyl-4-phenylindenyl)} zirconium bis (trifluoromethanesulfonic acid) , Dimethylsilylenebis {1- (2-ethyl-4-)
Phenylazulenyl) {zirconium bis (trifluoromethanesulfonic acid), dimethylsilylenebis} 1-
(2-ethyl-4-phenyl-4,5,6,7,8-pentahydroazulenyl) {zirconium bis (trifluoromethanesulfonic acid), dimethylsilylenebis} 1-
(2-ethyl-4- (pentafluorophenyl) indenyl) {zirconium dichloride, dimethylsilylene bis} 1- (2-ethyl-4-phenyl-7-fluoroindenyl)} zirconium dichloride, dimethylsilylenebis {1- ( 2-ethyl-4-indolylindenyl) zirconium dichloride, dimethylsilylenebis {1- (2-dimethylborano-4-indolylindenyl)} zirconium dichloride and the like.

Other metallocene transition metal complexes include:
For example, dimethylgermylene bis ((1-indenyl)
Zirconium dichloride, dimethylgermylene bis ｛1
-(2-methyl-4-phenylindenyl) {zirconium dichloride, dimethylgermylene bis} 1- (2-
Methyl-4,5-benzoindenyl) zirconium dichloride, methylaluminum bis (1-indenyl)
Zirconium dichloride, phenylphosphinobis (1
-Indenyl) zirconium dichloride, ethylholanobis (1-indenyl) zirconium dichloride, phenylaminobis (1-indenyl) zirconium dichloride and the like.

The catalyst component (b) may have a function as a cocatalyst component or a promoter component for the metallocene transition metal complex as the catalyst component (a). The catalyst component (b) can be used alone or in combination of two or more.

As the catalyst component (b), (b-1) an aluminum oxy compound, (b-2) an ionic compound capable of converting a metallocene-based transition metal complex into a cation (such as an organic boron compound), or a Lewis acid , (B-3) a clay mineral, or an ion-exchangeable layered compound.

The aluminum oxy compound (b-1) includes an aluminum oxy compound obtained by reacting one or more kinds of trialkylaluminum with water, and one or more kinds of trialkylaluminum and alkylboronic acid (methylboronic acid, Compounds obtained by reaction with ethylboronic acid, butylboronic acid, etc.). Specifically, as the aluminum oxy compound,
Examples include methylalumoxane, ethylalumoxane, propylalumoxane, butylalumoxane, isobutylalumoxane, methylethylalumoxane, methylbutylalumoxane, methylisobutylalumoxane, and the like. Preferred aluminum oxy compounds include:
Methyl alumoxane and methyl isobutyl alumoxane are included. The aluminum oxy compound (b-1) can be used alone or in combination of two or more.

An ionic compound capable of converting a metallocene-based transition metal complex to cationic or an ionic compound capable of converting a metallocene-based transition metal complex to cationic in the Lewis acid (b-2) (“Ionized ionic compound”) ) May be composed of an ionic cation component and an ionic anion component. The ionic valence of both the cation component and the anion component is not particularly limited. In the ionized ionic compound, examples of the cation component include a carbonium cation (such as triphenylcarbonium), an ammonium cation (such as triethylammonium), a phosphonium cation (such as triphenylphosphonium), and an oxonium cation (such as triphenyloxonium). ), A sulfonium cation (such as triphenylsulfonium), a metal cation (such as a silver ion or a gold ion) which is easily reduced or an organic metal cation (such as a ferrocenium ion). Examples of the anion component include an organic boron compound anion (such as tetraphenylboron and tetrakis (3,4,5-trifluorophenyl) boron), an organic aluminum compound anion (such as tetraphenylaluminum), and an organic gallium compound anion ( Tetraphenyl gallium), an organic phosphorus compound anion (such as tetraphenyl phosphorus), an organic arsenic compound anion (such as tetraphenyl arsenic), and an organic antimony compound anion (such as tetraphenyl antimony). It is important that the anion component is a component (generally non-coordinating) that becomes a counter anion to the converted cation species of the catalyst component (a).

As the Lewis acid, an organic boron compound is preferably used. The organic boron compound includes, for example, triphenylboron, tris (3,5-difluorophenyl) boron, tris (3,5-di (trimethylsilyl) phenyl) boron, tris (pentafluorophenyl) boron and the like. It is.

The ionic compound capable of converting the metallocene-based transition metal complex into a cationic one or the Lewis acid (b-2) can be used alone or in combination of two or more.

In the clay mineral or the ion-exchangeable layered compound (b-3), examples of the clay mineral include kaolin, bentonite, kibushi clay, gairome clay, allophane, hissingelite, pyrophyllite, talc, ummo, Examples include montmorillonite, vermiculite, lyocdeite, palygorskite, kaolinite, nacrite, dickite, halloysite, and the like. The clay mineral may be an ionic crystalline compound having a layered crystal structure.

The ion-exchangeable layered compound has a crystal structure in which surfaces formed by ionic bonds and the like are stacked in parallel with a weak bonding force, and contains exchangeable ions in the crystal structure. ing. The ion-exchange layered compound includes a crystalline acidic salt of a polyvalent metal, for example, α-Zr
(HPO ₄ ) ₂ , α-Ti (HPO ₄ ) ₂ , α-Sn (HP
O ₄ ) ₂ .H ₂ O, α-Zr (HAsO ₄ ) ₂ .H ₂ O, α-
Ti (HAsO ₄ ) ₂ .H ₂ O, γ-Zr (HPO ₄ ) ₂ ,
γ-Ti (HPO ₄ ) ₂ , γ-Ti (NH ₄ PO ₄ ) ₂ .H ₂
O and the like are included.

The clay mineral or the ion-exchange layered compound (b-3) can be used alone or as a mixture of two or more. Clay mineral or ion-exchangeable layered compound (b
As -3), a clay mineral such as montmorillonite can be suitably used.

In the present invention, a clay mineral or an ion-exchange layered compound (b-3) can be suitably used as the catalyst component (b).

The catalyst component (c) contains an organoaluminum compound. As the organic aluminum compound, for example, trimethyl aluminum, triethyl aluminum, tri n-propyl aluminum, tri n-butyl aluminum, triisobutyl aluminum, tri n-hexyl aluminum, tri n-octyl aluminum,
Tri-n-decylaluminum, diethylaluminum chloride, diethylaluminum sesquichloride, diethylaluminum hydride, diethylaluminum ethoxide, diethylaluminum dimethylamide, diisobutylaluminum hydride, diisobutylaluminum chloride and the like can be mentioned.

The catalyst component (c) can be used alone or in combination of two or more.

In the present invention, a metallocene catalyst or a metallocene-based transition metal complex (catalyst component (a)) can be used as a solid catalyst by holding a metallocene catalyst or a metallocene-based transition metal complex (catalyst component (a)) on a carrier using a fine solid as a carrier. Examples of the particulate solid include porous inorganic compounds such as silica and alumina, α-
Olefin (ethylene, propylene, 1-butene, etc.)
And a polymer or copolymer containing styrene as a main component of a monomer component. Further, the metallocene catalyst or the metallocene-based transition metal complex may be one obtained by preliminarily polymerizing in the presence of an olefin or the like. Examples of the olefin used for the prepolymerization include ethylene, propylene, butene-1, and 3-methylbutene-1.

In the present invention, the propylene-based random copolymer of the center layer 4 can be prepared by copolymerizing propylene and a copolymerizable monomer component for propylene using the metallocene catalyst as a catalyst component. it can. The copolymerization method is not particularly limited, and a known polymerization method using a metallocene catalyst can be employed. Any of a slurry method, a solution polymerization method, and a gas phase method can be used. Further, a continuous polymerization method, a batch polymerization method, a pre-polymerization method, or the like may be applied. In addition, as the polymerization solvent, for example, hexane, heptane, aliphatic hydrocarbons such as pentane, alicyclic hydrocarbons such as cyclohexane, benzene,
It is preferable to use an aromatic hydrocarbon such as toluene alone or as a mixture of two or more kinds. The polymerization temperature is from 0 to 15
You may choose from the range of 0 degreeC. Polymerization pressure is 0 to 90k
g / cm ² G (0 to 8.9 MPa (gauge pressure)). In addition, hydrogen may be used as a supplement as a molecular weight regulator.

The amount of the metallocene catalyst used is not particularly limited, and a known amount can be employed. For example, when a metallocene transition metal complex as the catalyst component (a) and an aluminum oxy compound as the catalyst component (b) are used in combination, the aluminum atom (Al) in the aluminum oxy compound and the metallocene transition metal In terms of the atomic ratio (molar ratio) of transition metal atoms (Me) in the complex (Al / Me), 1 to 100,0
00, preferably 10 to 10,000, more preferably 50 to 5,000.
When an organoaluminum compound is used as the catalyst component (c), it can be selected from a range of 10 ⁵ (molar ratio) or less based on the catalyst component (A) (metallocene-based transition metal complex).

(Surface Layer) The surface layer 5 is composed of a uniaxial or biaxially oriented film made of an amorphous cyclic olefin polymer having a glass transition temperature (Tg) in the range of 60 to 150 ° C.

The above-mentioned amorphous cyclic olefin polymer includes:
(A) a copolymer of an α-olefin such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and at least one cyclic olefin (hereinafter, referred to as a copolymer)
And (B) a ring-opened polymer of a cyclic olefin or a hydrogenated product thereof. The polymers (A) and (B) each include a graft-modified product thereof.

Cyclic in the polymers (A) and (B)
Examples of the olefin include bicyclo [2.2.1].
Hept-2-ene (norbornene), tetracyclo
[4.4.0.1^2,5. 1^7,10] -3-dodecene, hex
Sacyclo [6.6.1.1^3,6. 1 ^10,13. 0^2,7. 0
^9,14] -4-heptadecene, octacyclo [8.8.
0.1^2,9.1^4,7. 1^11,18. 1^13,16. 0^3,8. 0
^12,17] -5-docosene, pentacyclo [6.6.1.
1^3,6. 0^2,7. 0^9,14] -4-Hexadecene, heptasi
Clo-5-icosene, heptacyclo-5-hemicos
, Tricyclo [4.3.0.1 ^2,5-3-decene,
Tricyclo [4.4.0.1^2,5-3-undecene,
Pentacyclo [6.5.1.1^3,6. 0^2,7. 0^9,13]-
4-pentadecene, pentacyclopentadecadiene, pe
Nantacyclo [4.7.0.1^2,5. 0^8,13. 1^9,12]-
3-pentadecene, nonacyclo [9.10.1.
1^4,7. 1^13,20. 1^15,18. 0^2,10. 0^12,21.
0^14,19Polycyclic cyclic olefins such as -5-pentacocene
And the like. These cyclic olefins are
A methoxycarbonyl, ethoxycarbonyl group, etc.
Alkyl groups such as ester groups and methyl groups, haloalkyl
Group, a cyano group, a substituent such as a halogen atom
Good.

The cyclic olefin copolymer (A) can be prepared, for example, by subjecting the α-olefin and the cyclic olefin to a so-called Ziegler catalyst in a hydrocarbon solvent such as hexane, heptane, octane, cyclohexane, benzene, toluene and xylene. Or by polymerization using a catalyst such as the above-mentioned metallocene catalyst. Such a cyclic olefin copolymer (A) is commercially available, and for example, trade name “Apel” (manufactured by Mitsui Chemicals, Inc.) can be used.

The ring-opening polymer of cyclic olefin or its hydrogenated product (B) is, for example, a metathesis polymerization (ring-opening polymerization) of one or more of the above-mentioned cyclic olefins with a molybdenum compound or a tungsten compound as a catalyst. ) And usually hydrogenating the obtained polymer. Such a polymer (B) is commercially available, for example, trade name “ARTON” (manufactured by Nippon Synthetic Rubber Co., Ltd.),
Product name "Zeonex", product name "Zeonor" (
Nippon Zeon Co., Ltd.) can be used.

The preferred amorphous cyclic olefin polymer is a ring-opened polymer of the above-mentioned cyclic olefin or a hydrogenated product thereof (B). A ring-opened polymer of a cyclic olefin or a hydrogenated product thereof (B) is less likely to form a gel than a cyclic olefin copolymer (A), and is less likely to be degraded in steps such as mixing and melt extrusion during film formation. . This is because the cyclic olefin copolymer (A) has a structure in which residue portions of a chain olefin (α-olefin) and residue portions of a cyclic olefin are randomly arranged. In the ring-opened polymer or its hydrogenated product (B), the structure corresponding to the chain olefin in the cyclic olefin copolymer (A) and the structure corresponding to the cyclic olefin are regularly arranged. It seems to have.

Further, when a ring-opened polymer of cyclic olefin or its hydrogenated product (B) is used as the amorphous cyclic olefin polymer, the gel is hardly formed, and the impact resistance and printability of the base film are reduced. (There is less fisheye). Therefore, for example, even when the base film is stretched, tearing or puncturing can be prevented, and tearing can be prevented even in a subsequent step such as printing. In particular, substantially uniaxially stretched film in the transverse direction suitable as a heat-shrinkable label is easy to tear in the transverse direction, but because gel is not easily generated,
This is preferable because tearing from the gel does not occur.

The glass transition temperature (Tg) of the amorphous cyclic olefin polymer is from 60 to 150 ° C., preferably from about 60 to 120 ° C. If the glass transition temperature is lower than 60 ° C., the heat resistance is poor, and if it exceeds 150 ° C., the label tends to be brittle.

In the present invention, the glass transition temperature (Tg) of the amorphous cyclic olefin polymer is 60 to 80 ° C.
(Preferably 60 to 75 ° C.), particularly 65 ° C.
~ 75 ° C (especially about 70 ° C) is optimal. The glass transition temperature (Tg) of the amorphous cyclic olefin-based polymer can be adjusted by the type of the monomer component (for example, cyclic olefin, etc.) and the mixing ratio thereof. When the glass transition temperature is in the range of 60 to 80 ° C, the low-temperature heat shrinkability can be further enhanced.

The amorphous cyclic olefin polymer can be used alone or in combination of two or more. The base film 2 or the surface layer 5 may further contain, if necessary, a small amount of another polymer as long as the solvent sealing property or the like is not impaired. In addition, in order to prevent fusion between the films, the base film 2 or the surface layer 5 contains inorganic fine particles. You may go out. As the inorganic fine particles, for example,
Inorganic oxides such as silica, alumina, zinc oxide and magnesium oxide; carbonates such as calcium carbonate and magnesium carbonate; silicates such as calcium silicate, glass beads, talc, clay and mica. The average particle diameter of the inorganic fine particles is, for example, 1 to 10 μm, preferably 3 μm.
About 7 μm. The amount of the inorganic fine particles is, for example, 0.1% with respect to the total amount of the constituent components of the base film 2 or the surface layer 5.
0.5 to 0.50% by weight, preferably 0.08 to 0.30
It can be selected from a range of about weight%.

In the present invention, the thickness of the base film 2 is
For example, it is about 20 to 80 μm, preferably about 30 to 60 μm.

The thickness of the center layer 4 in the base film 2 is, for example, 10 to 70 μm, preferably 20 to 50 μm.
It can be selected from a range of about m. The thicknesses of the surface layers 5 and 5 in the base film 2 are respectively
For example, it can be selected from a range of about 3 to 15 μm, preferably about 5 to 10 μm.

The center layer 4 may contain a so-called tackifier, for example, a petroleum resin, a terpene resin, a rosin resin, a coumarone-indene resin, a styrene resin, or the like. The amount of these tackifiers can be selected, for example, from the range of about 5 to 30% by weight based on the total amount of the constituent components of the center layer 4. Further, other polymers such as polyethylene may be contained in a small amount. Also,
The central layer 4 may contain the amorphous cyclic olefin polymer used for the surface layer 5, and its content is preferably 30% by weight or less based on the total amount of the constituent components of the central layer 4. .

The surface of the surface layer 5 on the printing layer 3 side may be subjected to a conventional surface treatment such as a corona discharge treatment, a plasma treatment, a flame treatment, and an acid treatment in order to improve printability. In addition, the center layer 4 and the surface layer 5 may have
Lubricants, fillers, heat stabilizers, antioxidants, UV absorbers,
Various additives such as an antistatic agent, a flame retardant, and a coloring agent may be added.

The center layer 4 and the surface layer 5 can be composed of a plurality of layers. Further, another resin layer may be provided between the center layer 4 and the surface layer 5 as long as rigidity and natural shrinkage are not impaired. The surface of the surface layer 5 is made of acrylic resin to prevent damage. An overcoat layer made of a base resin or the like may be provided.

The base film 2 in the present invention can be produced by a conventional method used for producing a single-layer film or a laminated film, for example, an extrusion method, a co-extrusion method and the like. For example, the base film 2 shown in FIG. 1 includes a resin composition containing a resin forming the central layer 4 and surface layers 5 and 5.
A resin composition containing a resin forming a T-die,
It can be obtained by melt extrusion using a feed block two-type three-layer type extruder, cooling by a cooling roll, and stretching. In the base film 2 shown in FIG. 1, since both the center layer 4 and the surface layers 5 and 5 are formed of an olefin-based polymer, they can be laminated without using an adhesive. An adhesive layer may be interposed. Note that an annular die can be used instead of the T die.

The stretching can be performed by any of a tenter method and a tube method. The stretching process is usually performed at 80
The stretching is performed at a temperature of about 180 ° C. (preferably 80 ° C. to 150 ° C.) by stretching 4 to 8 times, preferably 5 to 7 times in the width direction (lateral direction; TD direction). In addition, if necessary, for example, a stretching process can be performed at a low stretching ratio (for example, about 1.5 times or less) also in the length direction (longitudinal direction; MD direction). The base film in the present invention thus includes a uniaxially oriented film stretched in only one direction, and a biaxially oriented film stretched mainly in one direction and slightly stretched in a direction perpendicular to the direction. It is. That is, the film is substantially uniaxially stretched in the lateral direction.

The base film 2 thus obtained has an orientation in the width direction (mainly the direction subjected to the stretching treatment) and exhibits heat shrinkage in the direction.

In the heat-shrinkable label of the present invention, the base film 2 is immersed in hot water at 90 ° C. for 10 seconds, and is immersed in the main orientation direction X (the direction in which the stretching process is mainly performed; the width direction in the above case). The heat shrinkage (hereinafter sometimes referred to as “heat shrinkage A”) is, for example, 30 to 80%, preferably 4
Desirably, it is about 0 to 70%. In the present invention, since such physical properties can be imparted to the base film, heat shrinkage is possible at a low temperature and a low calorific value. For this reason,
For example, it can be easily and easily attached to a container having a curved surface. The heat shrinkage A is expressed by the following equation. Heat shrinkage A (%) = [(original length in direction X)-(length after immersion in direction X)] / (original length in direction X) × 10
0

Further, after the base film 2 is immersed in hot water of 80 ° C. for 10 seconds, the heat shrinkage rate in the main orientation direction X (direction in which the stretching treatment is mainly performed; Heat shrinkage B ”).
It is desirably about 25 to 50%, preferably about 30 to 50%. When the base film has such physical properties, heat shrinkage becomes possible at a lower temperature and calorie, and, for example, it can be easily and well adhered to a container having a curved surface. Note that the heat shrinkage B is expressed by the same formula as the heat shrinkage A.

The heat shrinkage is determined by the type of resin (melting point, glass transition point, etc.) constituting the base film 2, the center layer 4, and the surface layers 5, the thickness ratio between the center layer 4 and the surface layers 5, 5. It can be adjusted by appropriately selecting stretching conditions such as stretching ratio, stretching temperature and the like.

The heat-shrinkable label 1 of the present invention can be formed on at least one surface of the base film 2 obtained as described above by a conventional printing method such as gravure printing.
It can be manufactured by printing characters to form the print layer 3. Then, after forming the printing layer 3, it is usually cut into a long strip shape having a desired width, for example, with the printing surface inside, the direction X of the base film 2 becomes the circumferential direction, and the direction of the base film 2 becomes By rounding into a cylindrical shape so that the direction Y perpendicular to X is the length direction, and bonding both ends by a solvent or heat fusion, etc., by cutting to a desired length as necessary,
It can be a tubular heat-shrinkable label.

The printing ink for forming the printing layer 3 is not particularly limited, and a conventional printing ink can be used. However, an ink having a small change in color upon heat treatment of a boil or the like, for example, a reactive urethane-based ink It is preferable to use ink. The reactive urethane-based ink includes a two-component ink that uses a combination of a polyisocyanate prepolymer curing agent and a polyol such as a polyether polyol, a polyester polyol, an acrylic polyol, or an epoxy polyol as a resin constituting the vehicle. included.

In a preferred embodiment of the heat-shrinkable label of the present invention, the printing layer 3 is set inside, and the both edges are overlapped so that the direction X is the circumferential direction. ing. Such a label can be easily attached to a container having a cylindrical body, does not wrinkle unlike a heat-sealed label, has excellent gloss, and has a beautiful appearance.

Examples of the organic solvent include hydrocarbons such as pentane, hexane, cyclohexane, benzene and toluene; halogenated hydrocarbons such as methyl chloride, methylene chloride, chloroform, ethyl chloride, 1,2-dichloroethane and propyl chloride. Linear or cyclic ethers such as diethyl ether, diisopropyl ether, dibutyl ether, ethylene glycol dimethyl ether, tetrahydrofuran and dioxane; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as methyl acetate, ethyl acetate and butyl acetate. Among these, an organic solvent having a boiling point of about 20 to 70 ° C., particularly about 25 to 50 ° C. is preferable in terms of workability and the like.

As described above, the heat shrinkable label of the present invention is
Since the surface layer in the base film is formed of the amorphous cyclic olefin polymer and the center layer is formed of the propylene random copolymer, while taking advantage of the amorphous cyclic olefin polymer, The amount of expensive amorphous cyclic olefin polymer used can be reduced, which is advantageous in cost.

In particular, the heat-shrinkable label of the present invention is excellent in low-temperature shrinkage because the center layer is formed of a propylene-based random copolymer produced using a metallocene catalyst, and is shrinkable at low temperature. However, high label strength can be exhibited, and the appearance characteristics and printing characteristics are good. Therefore, the polyolefin-based heat-shrinkable label of the present invention is PE
It is useful as a heat-shrinkable label for a plastic container such as a T-bottle or a polystyrene container, which is easily deformed by heat, or a container whose contents are easily deformed by heat, such as pharmaceuticals, seasonings, and health drinks. That is, even when used for a container having a content that is apt to undergo thermal deformation or a content that is susceptible to thermal deterioration, such as a thin polyethylene terephthalate bottle,
It is possible to suppress or prevent the thermal deformation of the container and the thermal deterioration of the contents due to the heat during the heat shrinkage. In the present invention, the low-temperature shrinkage means, for example, shrinkage at a temperature of about 70 to 90 ° C.

Further, since a material having excellent heat resistance can be obtained, a decrease in label strength can be suppressed or prevented even when heated or heated by a hot bender or the like. In addition, a reduction in the appearance of the label can be suppressed or prevented.

Further, since the sheet has excellent gloss and good transparency, printing is beautiful. Further, upon heat shrinkage, the shrinkage speed is fast, and after the heat source is separated, it does not loosen even after passing through the day, and is excellent in the fitting property (adhesion, tightening property).
In addition, since the amorphous cyclic olefin polymer has an amorphous and bulky group, it can be easily sealed with an organic solvent. For this reason, wrinkles and the like hardly occur, and the appearance is good. Further, since the stiffness is high, the speed of the production line can be increased, the productivity can be improved, and the thickness can be reduced, so that the cost can be reduced.

FIG. 2 is a schematic perspective view showing a state in which the heat-shrinkable label 1 of FIG. 1 is mounted on an object 6 (for example, a plastic or glass bottle such as a PET bottle). . The same members and portions are denoted by the same reference numerals.

The tubular heat-shrinkable label 1 obtained as described above is supplied to an automatic label mounting apparatus, cut into a required length, and continuously cut on the mounting object 6 filled with ordinary contents. And a steam tunnel at a predetermined temperature (for example, 70
To 90 ° C., preferably about 75 to 85 ° C.) or a hot air tunnel (for example, about 100 to 200 ° C.) to cause heat shrinkage, whereby the heat shrinkable label 1 is attached to the object 6.
Can be attached to At this time, since the label fitted to the mounted object 6 is thermally contracted, the label fits and adheres to the shape of the shoulder of the mounted object 6 and the like. In addition, the heat-shrinkable label obtained by the present invention is attached to a heat-resistant container such as a glass bottle, and after filling the contents, boil-treated. It is not spoiled.

Since the olefin-based heat-shrinkable label of the present invention uses a polyolefin-based resin, its specific gravity is different from that of polyester (polyethylene terephthalate). Sometimes, separation of the polyolefin-based resin, which is a plastic component of the heat-shrinkable label, and polyethylene terephthalate of the bottle becomes easy.

[0079]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 An ethylene-propylene random copolymer (ethylene content: 4.3% by weight, melting point: 123 ° C.) (a1) obtained using a metallocene catalyst, and an amorphous cyclic olefin polymer (Product name "Apel APL6509", Tg: 80 ° C,
Mixture (b) of 100 parts by weight of a cyclic olefin copolymer (manufactured by Mitsui Chemicals, Inc., density: 1.02 g / cm ³ ) and 0.5 parts by weight of inorganic fine particles (spherical silica, average particle size: 1.5 μm)
1) is co-extruded from a T-die at a temperature of 280 ° C. using a combined feed block two-type and three-layer extruder, and then stretched 6.0 times in the width direction (TD direction) at 100 ° C. As a result, a base film having a layer structure of (b1) / (a1) / (b1) and a thickness of 60 μm (thickness of the center layer (a1): 52 μm, thickness of the surface layer (b1): 4 μm) was obtained.

From this base film, 10 cm × 10 c
m (length in width direction (TD direction) x length direction (MD direction)
Length), and immersed in warm water at 90 ° C. for 10 seconds, and then cut in the width direction (T
The length in the direction D) was measured, and the heat shrinkage A was determined by the above equation. The heat shrinkage was 61% (90 ° C. × 10 seconds).

One surface of the base film obtained as described above is subjected to gravure printing of a design consisting of eight colors using a reactive urethane-based ink to form a printed layer, and to prevent damage to the other surface. An overcoat layer made of an acrylic resin was formed and wound into a roll. After slitting the obtained printing roll into a predetermined width to form a plurality of rolls, each roll is rewound and formed into a cylindrical shape such that the width direction (TD direction) of the base film is the circumferential direction. It was rolled up and both ends were adhered with an organic solvent (cyclohexane) to obtain a long tube-shaped continuous heat-shrinkable label. This continuous heat-shrinkable label is supplied to an automatic label mounting apparatus, cut into each label, and then externally fitted into a 1.5 L PET bottle container (a container made of polyethylene terephthalate) and passed through a steam tunnel (temperature: 80 ° C.). The container was attached to the container by heat contraction. As a result, the adhesion of the label to the bottle was high, and the tightness was excellent. Further, when the container equipped with the label was stored at 60 ° C. for 21 days, there was no problem in appearance and label strength.

Example 2 100 parts by weight of an ethylene-propylene random copolymer (ethylene content: 4.3% by weight, melting point: 123 ° C.) obtained by using a metallocene catalyst were added to a hydrogenated petroleum resin (trade name: A mixture of 25 parts by weight of Alcon P-140 (manufactured by Arakawa Chemical Co., Ltd.) (a1) and an amorphous cyclic olefin polymer (trade name “ZEONOR 750R”, density 1.0 g / c)
m ³ , Tg 70 ° C., manufactured by Nippon Zeon Co., Ltd .; 100 parts by weight of a cyclic olefin ring-opening polymer or a hydrogenated product thereof) and 0.5 parts by weight of inorganic fine particles (amorphous silica, average particle diameter of 2 to 3 μm) (B1) was extruded from a T-die using an extruder at a temperature of 220 ° C., and then stretched by a factor of 5.5 in the width direction (TD direction) at 90 ° C. to obtain (b1) /
(A1) / (b1) having a three-layer structure and a thickness of 50 μm (thickness of the central layer (a1): 38 μm, thickness of the surface layer (b1): 6 each)
μm) base film was obtained.

From this base film, 10 cm × 10 c
m (length in width direction (TD direction) x length direction (MD direction)
Length), immersed in hot water at 80 ° C. for 10 seconds, and then immersed in the width direction (T
The length in the direction D) was measured, and the heat shrinkage B was determined by the above equation. The heat shrinkage B was 33%.

Except for using the base film obtained as described above, a continuous tubular heat-shrinkable label was obtained in the same manner as in Example 1. The printing was beautiful and good without fish eyes. The heat-shrinkable label continuum is supplied to an automatic label mounting device, and cut into individual labels.
Externally fitted to a 5L PET bottle container (a container made of polyethylene terephthalate), and a steam tunnel (temperature: 80)
C.) and heat-shrinked to attach to the container. As a result, the adhesion of the label to the bottle was high, and the tightness was excellent.

Comparative Example 1 A commercially available ethylene-propylene random copolymer prepared without using a metallocene catalyst (ethylene content: 4.
(3% by weight, melting point: 137 ° C.) except that a base film was prepared in the same manner as in Example 1 to prepare a continuous heat-shrinkable label in the form of a long tube, which was attached to a PET bottle. . As a result, the shrinkage rate of the label was slow, the adhesion and the tightening property of the label to the bottle were not sufficient, and the finished appearance was poor.

[0087]

According to the heat-shrinkable label of the present invention, since the surface layer and the center layer of the base film are each composed of a specific resin, the heat-shrinkable label is lower in temperature than the conventional polyolefin-based heat-shrinkable label. Excellent heat shrinkage. That is, since it has good low-temperature shrinkability, it can be used for plastic containers such as PET bottles and polystyrene containers, which are easily deformed by heat, containers for drugs, seasonings, and health drinks whose contents are easily degraded by heat. High availability. Further, since a material having excellent heat resistance can be obtained, it can be stored under heat and heat retention.

By using a ring-opened polymer of a cyclic olefin or a hydrogenated product thereof as the amorphous cyclic olefin polymer of the surface layer, the printability is good and the impact resistance can be further enhanced. It is.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a heat shrinkable label of the present invention.

FIG. 2 is a schematic perspective view showing a state when the heat-shrinkable label of FIG. 1 is mounted on an object.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat-shrinkable label 2 Base film 3 Printing layer 4 Center layer 5 Surface layer 6 Attached object

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuo Ose 5-3-1, Imazukita, Tsurumi-ku, Osaka F-Term in Fuji Seal Co., Ltd. (Reference) 3E062 AA09 AB02 AC02 DA02 DA07 4F100 AK07C AK07D AK51A AK51E AK64C AK64D AK80B AL03C AL03D BA04 BA05 BA07 BA10A BA10B CC00A CC00E GB90 HB31A HB31E JA04C JA04D JA05B JA12B JJ00B JJ00C JJ00D JJ03 JL08C JL08D YY00B YY00C YY00C

Claims (8)

[Claims] 1. A heat-shrinkable label having a printing layer provided on at least one surface of a base film, wherein the base film has a glass transition temperature (Tg) of 60 to 150.
Polyolefin-based heat shrinkage composed of a surface layer composed of an amorphous cyclic olefin-based polymer in the range of ℃ and a central layer composed of a propylene-based random copolymer obtained by copolymerization with a metallocene catalyst. label. 2. The base film is placed in hot water at 80 ° C. for 10 minutes.
Heat shrinkage in the main orientation direction X when immersed for 2 seconds
The polyolefin-based heat-shrinkable label according to claim 1, which is 5 to 50%. 3. The propylene-based random copolymer is an ethylene-propylene random copolymer.
The heat-shrinkable polyolefin label according to the above. 4. The polyolefin-based heat-shrinkable label according to claim 3, wherein the proportion of the ethylene component in the ethylene-propylene random copolymer is 3 to 4.5% by weight based on the total amount of the monomer components of the copolymer. . 5. The heat-shrinkable polyolefin label according to claim 3, wherein the ethylene-propylene random copolymer has a melting point of 120 to 130 ° C. 6. The method according to claim 1, wherein the amorphous cyclic olefin polymer is a cyclic olefin ring-opening polymer or a hydrogenated product thereof.
6. The polyolefin-based heat-shrinkable label according to any one of items 5 to 5. 7. The heat-shrinkable polyolefin label according to claim 1, wherein the printing layer is formed of a reactive urethane ink. 8. The heat-shrinkable polyolefin-based label according to claim 1, wherein the label is formed in a cylindrical shape such that the direction X is the circumferential direction.