JP5075263B2 - Shrink label - Google Patents

Description

The present invention relates to a shrink label having a base film made of a multilayer film that is excellent in low temperature resistance, oil resistance, cut performance at perforations and appearance, and that does not peel off during mounting.

In recent years, many containers such as plastic bottles and metal bottles are provided with a shrink label obtained by printing or the like on a base film made of a heat-shrinkable resin film.
As shrink labels, those made of polystyrene resin are the mainstream because of their excellent low temperature shrinkability. However, the polystyrene-based resin film has a low low temperature elongation, and there is a problem that the shrink label may be broken when it is accidentally dropped during refrigerated storage. In addition, since the polystyrene-based resin film has insufficient solvent resistance, there is a problem that when it is used for packaging an article containing oil, it may shrink or dissolve due to adhesion of the oil. It was.

On the other hand, an attempt has been made to use a polyester film excellent in low temperature resistance and solvent resistance as a shrink label instead of the polystyrene resin film. However, the polyester film has poor low-temperature shrinkability and has a problem that wrinkles are easily generated when the polyester film is attached to a container. In addition, the shrink film is often provided with a perforation for peeling so that the shrink label can be easily peeled off from the container after use in order to recycle the container. There was also a problem that the cut property at the perforation was poor and the shrink label could not be easily peeled off from the container.

On the other hand, Patent Document 1 discloses a hard multilayer shrinkable film in which an outer layer made of a polyester resin is laminated on an intermediate layer made of a polystyrene resin through an adhesive layer made of an olefin resin. ing. In Patent Document 2, an outer surface layer made of a polyester resin made of a specific monomer is laminated on both sides of an intermediate layer made of a polystyrene resin, and the intermediate layer and the outer surface layer form an adhesive layer. A shrink label provided with a base film laminated without being interposed is disclosed. Shrink labels made of these multilayer films are excellent in low-temperature shrinkage and perforation cutability by an intermediate layer made of polystyrene resin, and because the intermediate layer is covered by an outer surface layer made of polyester resin, Excellent solvent resistance and low temperature resistance. However, when these shrink labels are actually attached to the container, the hard multilayer shrinkable film described in Patent Document 1 may cause the intermediate layer and the outer surface layer to be peeled off during the attachment. In the shrink label described in, peeling between the inner surface layer and the outer surface layer may occur when the films are rubbed during transportation of the product after being mounted, or when scratched by human nails or objects. There was a problem that there was.

JP 61-41543 A JP 2002-351332 A

In view of the above situation, the present invention aims to provide a shrink label having a base film made of a multilayer film that is excellent in low temperature resistance, oil resistance, cut performance at perforations, and has an appearance that does not peel off during mounting. And

The present invention is a shrink label having a base film made of a heat-shrinkable multilayer resin film comprising an intermediate layer made of polystyrene resin and an outer surface layer made of polyester resin sandwiching the intermediate layer. The polystyrene-based resin is a mixed resin of an aromatic vinyl hydrocarbon-conjugated diene copolymer and an aromatic vinyl hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymer, and is a polyester-based resin that constitutes the outer surface layer. The resin contains a component derived from terephthalic acid as a dicarboxylic acid component, and the intermediate layer and the outer layer are at least selected from the group consisting of a carboxylic acid group, an acid anhydride group, an amino group, an epoxy group, and a hydroxyl group. Adhered by an adhesive layer comprising a hydrogenated aromatic vinyl hydrocarbon-conjugated diene copolymer having one kind of functional group in the molecule. The content of the functional group in the hydrogenated product of the aromatic vinyl hydrocarbon-conjugated diene copolymer is 0.05 to 5.0% by weight, and the thickness of the adhesive layer is 0.7 to 1 Shrink label that is 5 μm.
The present invention is described in detail below.

The present inventors provide a shrink label having a base film made of a heat-shrinkable multilayer resin film comprising an intermediate layer made of polystyrene resin and an outer surface layer made of polyester resin sandwiching the intermediate layer. When the layers are bonded via a specific adhesive layer, it has been found that delamination does not occur and can be stably mounted, and the present invention has been completed.

As a method of attaching the shrink label to the container, usually, the end portions of the shrink film are bonded to each other using a solvent and processed into a tube shape (center seal processing), and then heated while covering the container to form the film. The method of contracting is adopted.

FIG. 1 is a schematic diagram showing a state in the vicinity of the center seal portion in a series of mounting steps when the shrink label of the present invention is used, and FIG. 2 uses a conventional shrink label using a multilayer film as a base film. The schematic diagram which shows the state of the center seal | sticker part vicinity in a series of mounting processes in the case was shown.
When the present inventors investigated in detail the state of mounting failure when a conventional shrink label using a multilayer film as a base film was used, the shrink label described in Patent Document 2 is shown in FIG. As shown, the inner layer 1 and the outer layer 2 after heat-shrinking after center sealing and when the films are rubbed during transportation of the product after heat-shrinking or when scratched by human nails or objects. (For comparison, in FIG. 2 (a), the film is peeled off at the end of the film, but not only at the end of the film. Also, peeling may occur in the central portion or the like). Moreover, in the shrink label described in Patent Document 1, as shown in FIG. 2 (b), when the heat is shrunk after the center seal, between the outer surface layer 2 on the center seal side and the adhesive layer 3 ′. It was found that peeling occurred.

In the shrink label described in Patent Document 2, the inner surface layer 1 and the outer surface layer 2 are directly laminated without using an adhesive layer. In Patent Document 2, it is said that by using an outer surface layer made of a polyester-based resin made of a specific monomer, the affinity between the inner surface layer 1 and the outer surface layer 2 is increased to increase the adhesive strength. It is considered that the adhesive strength between the layers was not high, and the layers were separated between the inner surface layer 1 and the outer surface layer 2.
On the other hand, in the shrink label described in Patent Document 1, since the inner surface layer 1 and the outer surface layer 2 are laminated via the adhesive layer 3 ′ made of an olefin resin, the adhesive strength between the layers should be high. . In the center seal method, the end portions of the shrink film are bonded using a solvent. At this time, as the solvent, a solvent that dissolves the polyester resin used for the outer surface layer is used, and a part of the outer surface layer is dissolved and bonded. The olefin resin used as the adhesive layer in Patent Document 1 has extremely high solvent resistance against a solvent for dissolving the polyester resin, and hardly dissolves or swells. Therefore, even if a part of the outer surface layer is dissolved at the center seal, the solvent does not penetrate into the inside of the shrink label, and the adhesive force between the dissolved outer surface layer and the adhesive layer on the inner side is reduced, and the heat is reduced. When stress is applied during the shrinkage, it is considered that the outer surface layer 1 and the adhesive layer 3 ′ have been separated.

On the other hand, in the shrink label of the present invention, as shown in FIG. 1, delamination did not occur even when heat shrinkage was performed after the center seal.
In the shrink label of the present invention, the inner surface layer 1 and the outer surface layer 2 have at least one functional group selected from the group consisting of a carboxylic acid group, an acid anhydride group, an amino group, an epoxy group, and a hydroxyl group in the molecule. Since the layers are laminated via the adhesive layer 3 made of a hydrogenated product of an aromatic vinyl hydrocarbon-conjugated diene copolymer, the adhesive strength between the layers is extremely high. Further, since the resin constituting the adhesive layer 3 dissolves or swells in a solvent that dissolves the polyester-based resin, the solvent penetrates into the interior of the shrink label and is bonded as a whole at the time of center sealing. Is made. For this reason, since the adhesive force between each layer improves more in a center seal part, it is thought that delamination does not occur.

The shrink label of the present invention uses, as a base film, a heat-shrinkable multilayer resin film composed of an intermediate layer made of polystyrene resin and an outer surface layer made of polyester resin sandwiching the intermediate layer.
The polystyrene resin constituting the intermediate layer is a mixed resin of an aromatic vinyl hydrocarbon-conjugated diene copolymer and an aromatic vinyl hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymer. Since a film made of such a mixed resin is excellent in low-temperature elongation, the resulting shrink film has high low-temperature resistance and excellent cut performance at perforations.

The aromatic vinyl hydrocarbon-conjugated diene copolymer is not particularly limited. For example, aromatic vinyl hydrocarbons include styrene, o-methylstyrene, p-methylstyrene and the like, and conjugated dienes are 1,3- Examples include butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like. These may be used alone or in combination of two or more. Among these, a styrene-butadiene-styrene copolymer (SBS resin) is preferable because it is particularly excellent in low-temperature shrinkage and cut performance at perforations. In order to produce a film with less fish eye, a styrene-isoprene-styrene copolymer (SIS resin) using 2-methyl-1,3-butadiene (isoprene) as a conjugated diene, or a styrene-isoprene. It is preferable to use a butadiene-styrene copolymer (SIBS resin) or the like.

When SBS resin, SIS resin or SIBS resin is used as the aromatic vinyl hydrocarbon-conjugated diene copolymer, the styrene content is 65 to 85% by weight and the conjugated diene content is 15 to 35% by weight. Is preferably used. A resin having such a composition is particularly excellent in low-temperature shrinkage and perforation.

Further, as the aromatic vinyl hydrocarbon-conjugated diene copolymer, an aromatic vinyl hydrocarbon-conjugated diene copolymer having isoprene as a conjugated diene component may be used. In particular, when an aromatic vinyl hydrocarbon-conjugated diene copolymer having a large proportion of butadiene is used, crosslinking due to the butadiene component is likely to proceed during molding, resulting in fish eyes or printability. Inconveniences such as deterioration will occur. On the other hand, when an aromatic vinyl hydrocarbon-conjugated diene copolymer having isoprene as a conjugated diene component is used, since crosslinking during molding is suppressed, generation of foreign substances such as gel can be prevented. .
This is because the butadiene component of the aromatic vinyl hydrocarbon-conjugated diene copolymer generates reactive radicals by heating during molding, thereby dehydrogenating other compounds or double bonds. It is considered that the isoprene component generates radicals having poor reactivity and is bonded to each other to suppress the progress of the crosslinking, while it is likely to cause chain crosslinking.

The aromatic vinyl hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymer is not particularly limited. Examples of the aromatic vinyl hydrocarbon include styrene, o-methylstyrene, p-methylstyrene, and the like. Examples of the acid ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate. These may be used alone or in combination of two or more.

When a styrene-butyl acrylate copolymer is used as the aromatic vinyl hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymer, the styrene content is 60 to 90% by weight, and the butyl acrylate content is 10 to 40. It is preferable to use what is weight%. By using the aromatic vinyl hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymer having such a composition, a shrink label excellent in low temperature resistance and perforation cutting property can be obtained.

The preferable lower limit of the blending amount of the aromatic vinyl hydrocarbon-conjugated diene copolymer in the mixed resin constituting the intermediate layer is 20% by weight, and the preferable upper limit is 80% by weight. If it is less than 20% by weight, the low-temperature elongation becomes low, and the shrink film may be torn when it is accidentally dropped during refrigerated storage. May increase. A more preferred lower limit is 30% by weight, and a more preferred upper limit is 70% by weight.

The polyester resin constituting the outer surface layer can be obtained by condensation polymerization of dicarboxylic acid and diol.
The dicarboxylic acid is not particularly limited. For example, o-phthalic acid, terephthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, octyl succinic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, fumaric acid, Examples include maleic acid, itaconic acid, decamethylene carboxylic acid, anhydrides and lower alkyl esters thereof.
The diol is not particularly limited. For example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, triethylene Glycol, tetraethylene glycol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, neopentyl glycol (2,2-dimethylpropane-1,3-diol), 1,2-hexane Aliphatic diols such as diol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol; 2-bis (4-hydroxycyclohexyl) propane, 2,2-bis (4-hydroxy) B carboxymethyl cyclohexyl) alkylene oxide adducts of propane, 1,4-cyclohexane diol, alicyclic diols such as 1,4-cyclohexanedimethanol.

Among these polyester-based resins, those containing a component derived from terephthalic acid as the dicarboxylic acid component and those derived from ethylene glycol and 1,4-cyclohexanedimethanol as the diol component are suitable. is there. By using such a polyester resin, particularly high low temperature resistance and solvent resistance can be imparted to the resulting shrink label of the present invention.
In addition, when imparting particularly high low temperature resistance and solvent resistance, the content of the component derived from ethylene glycol is 60 to 80 mol%, and the content of the component derived from 1,4-cyclohexanedimethanol is 10 It is preferable to use one that is ˜40 mol%. Such a polyester resin may further contain 0 to 20 mol% of a component derived from diethylene glycol.
As a polyester-type resin which comprises the said outer surface layer, the polyester-type resin which has the composition mentioned above may be used independently, and 2 or more types of polyester-type resins which have the composition mentioned above may be used together.

As the polyester resin, a resin having a crystal melting temperature of 240 ° C. or lower is preferably used. In the manufacture of shrink films, it is common practice to use stretched ear trimming pieces and recycled films as return materials again. Usually, such a return material is mixed with a polystyrene resin as a raw material for the intermediate layer. However, since the polystyrene resin and the polyester resin have different properties such as a melting point, the temperature is suitable for molding the polystyrene resin. When film molding is performed, the polyester resin may be extruded in an unmelted state. However, by using a polyester resin having a relatively low crystal melting temperature or no crystal melting temperature, it is possible to prevent an unmelted product of the polyester resin from becoming a foreign substance in the film after molding. On the other hand, when the crystal melting temperature exceeds 240 ° C., when molding as a return material, undissolved polyester-based resin remains as foreign matter on the film, resulting in appearance failure or ink at the time of printing. In some cases, a problem such as a printing failure occurs due to flying. More preferably, it is 220 degrees C or less.

In the heat-shrinkable multilayer resin film, the intermediate layer and the outer surface layer have at least one functional group selected from the group consisting of a carboxylic acid group, an acid anhydride group, an amino group, an epoxy group, and a hydroxyl group in the molecule. Are adhered by an adhesive layer made of a hydrogenated aromatic vinyl hydrocarbon-conjugated diene copolymer. Such an adhesive layer has a high affinity for either the polystyrene resin constituting the intermediate layer or the polyester resin constituting the outer surface layer, and can bond them with high strength. In addition, since it dissolves or swells in a solvent that dissolves the polyester resin constituting the outer surface layer, the solvent can penetrate into the interior of the shrink label during center sealing, and delamination occurs during subsequent heat shrinkage. Can be prevented. Furthermore, since it can be molded by the coextrusion method together with the intermediate layer and the outer surface layer, it is excellent in productivity.

Hydrogenation of an aromatic vinyl hydrocarbon-conjugated diene copolymer having in its molecule at least one functional group selected from the group consisting of the carboxylic acid group, acid anhydride group, amino group, epoxy group and hydroxyl group Although it does not specifically limit as a thing, For example, a maleic anhydride modified styrene-ethylene / butylene-styrene block copolymer (maleic anhydride modified SEBS resin), an amine modified styrene-ethylene / butylene-styrene block copolymer (amine modified) SEBS resin), amine-modified styrene-butadiene / butylene-styrene block copolymer (amine-modified SBBS resin) or carboxylic acid-modified styrene-butadiene / butylene-styrene block copolymer (carboxylic acid-modified SBBS resin) are suitable. .

Both the SEBS resin and the SBBS resin can be obtained by hydrogenating the SBS resin, and further, grafted with maleic anhydride or reacted with an amine compound, a carboxylic acid compound or the like to form an amine or carboxylic acid at the terminal portion. A modified product can be easily obtained by adding an acid.

Hydrogenation of an aromatic vinyl hydrocarbon-conjugated diene copolymer having in its molecule at least one functional group selected from the group consisting of the carboxylic acid group, acid anhydride group, amino group, epoxy group and hydroxyl group The preferable lower limit of the content of the aromatic vinyl hydrocarbon component in the product is 20% by weight, and the preferable upper limit is 80% by weight. When it is less than 20% by weight, delamination tends to occur when a shrink label is attached. When it exceeds 80% by weight, the tackiness of the adhesive layer is lowered, and sufficient adhesive strength may not be obtained. A more preferred upper limit is 50% by weight.

Hydrogenation of an aromatic vinyl hydrocarbon-conjugated diene copolymer having in its molecule at least one functional group selected from the group consisting of the carboxylic acid group, acid anhydride group, amino group, epoxy group and hydroxyl group The minimum with preferable content of the said functional group in a thing is 0.05 weight%, and a preferable upper limit is 5.0 weight%. If it is less than 0.05% by weight, the adhesion to the outer surface layer may be insufficient, and if it exceeds 5.0% by weight, the resin is thermally deteriorated when the functional group is added, and the gel Such a foreign matter may be easily generated. A more preferred lower limit is 0.1% by weight, and a more preferred upper limit is 3.0% by weight.

The preferable lower limit of the thickness of the intermediate layer is 22 μm, and the preferable upper limit is 37 μm. If it is less than 22 μm, sufficient low-temperature shrinkability may not be obtained or cut performance at perforations may not be obtained. If it exceeds 37 μm, sufficient low-temperature resistance cannot be obtained. A more preferred lower limit is 26 μm, and a more preferred upper limit is 36 μm.
The preferable lower limit of the thickness of the outer surface layer is 3 μm, and the preferable upper limit is 10 μm. If it is less than 3 μm, sufficient oil resistance and low temperature resistance may not be obtained, and if it exceeds 10 μm, sufficient cut performance may not be obtained. A more preferable lower limit is 4 μm, and a more preferable upper limit is 8 μm.
The preferable lower limit of the thickness of the adhesive layer is 0.7 μm, and the preferable upper limit is 1.5 μm. If it is less than 0.7 μm, sufficient adhesive strength may not be obtained, and if it exceeds 1.5 μm, the heat shrinkage characteristics may be deteriorated. A more preferable lower limit is 0.8 μm, and a more preferable upper limit is 1.3 μm.

The method for producing the heat-shrinkable multilayer resin film is not particularly limited, but a method of simultaneously forming each layer by a coextrusion method is preferable. For example, in co-extrusion using a T-die, any of a feed block method, a multi-manifold method, or a method using these in combination may be used as a lamination method. In particular, by setting the temperature after the portion where the resin of each layer joins to preferably 230 ° C. or higher, more preferably 240 ° C. or higher, a multilayer film having good adhesion of each layer can be obtained.

You may add additives, such as antioxidant, a heat stabilizer, a lubricant, an antistatic agent, an antiblocking agent, to the shrink label of this invention as needed. In particular, the generation of gel can be suppressed by adding a heat stabilizer or an antioxidant.

In the shrink label of the present invention, the heat-shrinkable multilayer resin film may be used as a base film, and other layers such as a print layer may be laminated as necessary.

ADVANTAGE OF THE INVENTION According to this invention, the shrink film which uses the multilayer film which is excellent in low temperature resistance, oil resistance, the cut property in a perforation, and an external appearance, and does not peel at the time of mounting | wearing can be provided.

It is a schematic diagram which shows the state of the center seal | sticker part vicinity in a series of mounting processes at the time of using the shrink label of this invention. It is a schematic diagram which shows the state of the center seal | sticker part vicinity in a series of mounting processes at the time of using the shrink label which uses the conventional multilayer film as a base film.

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

Example 1
As the outer surface layer, terephthalic acid was used as a dicarboxylic acid component, and a polyester resin containing 67 mol% of a component derived from ethylene glycol and 33 mol% of a component derived from 1,4-cyclohexanedimethanol was used as a diol component. . In this polyester resin, the melting point was not observed.
As an intermediate layer, a styrene-butadiene block copolymer (styrene 75 wt%, butadiene 25 wt%: Vicat softening point 83 ° C., MFR 6.0 g / 10 min) 50 wt%, styrene-butyl acrylate copolymer (styrene 85 A mixed resin of 50% by weight and 15% by weight of butyl acrylate: Vicat softening point 70 ° C., MFR 4.0 g / 10 min) was used.
As an adhesive layer, maleic anhydride-modified styrene-ethylene / butylene-styrene block copolymer (styrene content 30% by weight, maleic anhydride addition amount 1.0% by weight, MFR 4.0 g / 10 min, specific gravity 0.92) Using.
Using these resins, a heat-shrinkable multilayer composed of five layers of outer surface layer (6 μm) / adhesive layer (1 μm) / intermediate layer (31 μm) / adhesive layer (1 μm) / outer surface layer (6 μm) by coextrusion. A resin film was extruded and used as a shrink label. In addition, the temperature after the part where each layer joins was 230 degreeC.

(Example 2)
As an outer surface layer, terephthalic acid is used as a dicarboxylic acid component, a component derived from ethylene glycol as a diol component is 70 mol%, a component derived from diethylene glycol is 10 mol%, and a component derived from 1,4-cyclohexanedimethanol is 20 A polyester resin containing mol% was used. In this polyester resin, the melting point was not observed.
As an intermediate layer, a styrene-butadiene block copolymer (styrene 75 wt%, butadiene 25 wt%: Vicat softening point 83 ° C., MFR 6.0 g / 10 min) 50 wt%, styrene-butyl acrylate copolymer (styrene 85 A mixed resin of 50% by weight and 15% by weight of butyl acrylate: Vicat softening point 70 ° C., MFR 4.0 g / 10 min) was used.
As an adhesive layer, maleic anhydride-modified styrene-ethylene / butylene-styrene block copolymer (styrene content 30% by weight, maleic anhydride addition amount 1.0% by weight, MFR 4.0 g / 10 min, specific gravity 0.92) Using.
Using these resins, a heat-shrinkable multilayer composed of five layers of outer surface layer (6 μm) / adhesive layer (1 μm) / intermediate layer (31 μm) / adhesive layer (1 μm) / outer surface layer (6 μm) by coextrusion. A resin film was extruded and used as a shrink label. In addition, the temperature after the part where each layer joins was 230 degreeC.

(Example 3)
As the outer surface layer, terephthalic acid was used as a dicarboxylic acid component, and a polyester resin containing 67 mol% of a component derived from ethylene glycol and 33 mol% of a component derived from 1,4-cyclohexanedimethanol was used as a diol component. .
As an intermediate layer, styrene-butadiene-styrene copolymer (styrene 75% by weight, butadiene 25% by weight: Vicat softening point 83 ° C., MFR 6.0 g / 10 min) 50% by weight, and styrene-butyl acrylate copolymer ( A mixed resin composed of 85% by weight of styrene and 15% by weight of butyl acrylate: Vicat softening point 70 ° C., MFR 4.0 g / 10 min) 50% by weight was used.
As an adhesive layer, a maleic anhydride-modified styrene-ethylene / butylene-styrene block copolymer (styrene content 30 wt%, maleic anhydride addition amount 0.5 wt%, MFR 4.0 g / 10 min, specific gravity 0.91) Using.
Using these resins, a heat-shrinkable multilayer composed of five layers of outer surface layer (6 μm) / adhesive layer (1 μm) / intermediate layer (31 μm) / adhesive layer (1 μm) / outer surface layer (6 μm) by coextrusion. A resin film was extruded and used as a shrink label. In addition, the temperature after the part where each layer joins was 240 degreeC.

Example 4
As the outer surface layer, terephthalic acid was used as a dicarboxylic acid component, and a polyester resin containing 67 mol% of a component derived from ethylene glycol and 33 mol% of a component derived from 1,4-cyclohexanedimethanol was used as a diol component. .
As an intermediate layer, a styrene-butadiene block copolymer (styrene 75 wt%, butadiene 25 wt%: Vicat softening point 83 ° C., MFR 6.0 g / 10 min) 50 wt%, styrene-butyl acrylate copolymer (styrene 85 A mixed resin of 50% by weight and 15% by weight of butyl acrylate: Vicat softening point 70 ° C., MFR 4.0 g / 10 min) was used.
As the adhesive layer, an amine-modified styrene-ethylene / butylene-styrene block copolymer (styrene content 30% by weight, MFR 4.0 g / 10 min, specific gravity 0.91, amino group at the terminal) was used.
Using these resins, a heat-shrinkable multilayer composed of five layers of outer surface layer (6 μm) / adhesive layer (1 μm) / intermediate layer (31 μm) / adhesive layer (1 μm) / outer surface layer (6 μm) by coextrusion. A resin film was extruded and used as a shrink label. In addition, the temperature after the part where each layer joins was 240 degreeC.

(Example 5)
As the outer surface layer, terephthalic acid was used as a dicarboxylic acid component, and a polyester resin containing 67 mol% of a component derived from ethylene glycol and 33 mol% of a component derived from 1,4-cyclohexanedimethanol was used as a diol component. .
As an intermediate layer, a styrene-butadiene block copolymer (styrene 75% by weight, butadiene 25% by weight: Vicat softening point 83 ° C., MFR 6.0 g / 10 min) 30% by weight, styrene-butyl acrylate copolymer (styrene 85 A mixed resin with 70% by weight of 15% by weight, 15% by weight of butyl acrylate: Vicat softening point 70 ° C., MFR 4.0 g / 10 min) was used.
As an adhesive layer, maleic anhydride-modified styrene-ethylene / butylene-styrene block copolymer (styrene content 30% by weight, maleic anhydride addition amount 1.0% by weight, MFR 4.0 g / 10 min, specific gravity 0.92) Using.
Using these resins, a heat-shrinkable multilayer composed of five layers of outer surface layer (6 μm) / adhesive layer (1 μm) / intermediate layer (31 μm) / adhesive layer (1 μm) / outer surface layer (6 μm) by coextrusion. A resin film was extruded and used as a shrink label. In addition, the temperature after the part where each layer joins was 240 degreeC.

(Example 6)
As the outer surface layer, terephthalic acid was used as a dicarboxylic acid component, and a polyester resin containing 67 mol% of a component derived from ethylene glycol and 33 mol% of a component derived from 1,4-cyclohexanedimethanol was used as a diol component. .
As an intermediate layer, a styrene-butadiene block copolymer (styrene 75 wt%, butadiene 25 wt%: Vicat softening point 83 ° C., MFR 6.0 g / 10 min) 50 wt%, styrene-butyl acrylate copolymer (styrene 85 A mixed resin of 50% by weight and 15% by weight of butyl acrylate: Vicat softening point 70 ° C., MFR 4.0 g / 10 min) was used.
As an adhesive layer, maleic anhydride-modified styrene-ethylene / butylene-styrene block copolymer (styrene content 30% by weight, maleic anhydride addition amount 1.0% by weight, MFR 4.0 g / 10 min, specific gravity 0.92) Using.
Using these resins, a heat-shrinkable multilayer consisting of five layers of outer surface layer (9 μm) / adhesive layer (1 μm) / intermediate layer (25 μm) / adhesive layer (1 μm) / outer surface layer (9 μm) by coextrusion. A resin film was extruded and used as a shrink label. In addition, the temperature after the part where each layer joins was 230 degreeC.

(Example 7)
As the outer surface layer, terephthalic acid was used as a dicarboxylic acid component, and a polyester resin containing 67 mol% of a component derived from ethylene glycol and 33 mol% of a component derived from 1,4-cyclohexanedimethanol was used as a diol component. .
As an intermediate layer, styrene-isoprene-butadiene-styrene copolymer (styrene 75% by weight, isoprene 10% by weight, butadiene 15% by weight: Vicat softening point 82 ° C., MFR 8.0 g / 10 min) 50% by weight, styrene- A mixed resin composed of 50% by weight of a butyl acrylate copolymer (85% by weight of styrene, 15% by weight of butyl acrylate: Vicat softening point 70 ° C., MFR 4.0 g / 10 min) was used.
As an adhesive layer, maleic anhydride-modified styrene-ethylene / butylene-styrene block copolymer (styrene content 30% by weight, maleic anhydride addition amount 1.0% by weight, MFR 4.0 g / 10 min, specific gravity 0.92) Using.
Using these resins, a heat-shrinkable multilayer composed of five layers of outer surface layer (6 μm) / adhesive layer (1 μm) / intermediate layer (31 μm) / adhesive layer (1 μm) / outer surface layer (6 μm) by coextrusion. A resin film was extruded and used as a shrink label. In addition, the temperature after the part where each layer joins was 230 degreeC.

(Example 8)
As an outer surface layer, 94 mol% of terephthalic acid as a dicarboxylic acid component, 6 mol% of adipic acid, 88 mol% of a component derived from ethylene glycol as a diol component, and 12 mol% of a component derived from 1,4-cyclohexanedimethanol 70% by weight of polyester resin (melting point 211 ° C.), terephthalic acid as the dicarboxylic acid component, 67 mol% of the component derived from ethylene glycol as the diol component, and 33 of the component derived from 1,4-cyclohexanedimethanol A mixed resin composed of 30% by weight of a polyester-based resin containing a mol% was used.
As an intermediate layer, styrene-butyl acrylate copolymer (styrene 85% by weight, butyl acrylate 15% by weight: Vicat softening point 70 ° C., MFR 4.0 g / 10 min) 70% by weight, styrene-isoprene-butadiene-styrene A mixed resin composed of 30% by weight of a copolymer (70% by weight of styrene, 15% by weight of isoprene, 15% by weight of butadiene: Vicat softening point 65 ° C., MFR 10 g / 10 min) was used.
As an adhesive layer, maleic anhydride-modified styrene-ethylene / butylene-styrene block copolymer (styrene content 30% by weight, maleic anhydride addition amount 1.0% by weight, MFR 4.0 g / 10 min, specific gravity 0.92) Using.
Using these resins, a heat-shrinkable multilayer composed of five layers of outer surface layer (6 μm) / adhesive layer (1 μm) / intermediate layer (31 μm) / adhesive layer (1 μm) / outer surface layer (6 μm) by coextrusion. A resin film was extruded and used as a shrink label. In addition, the temperature after the part where each layer joins was 230 degreeC.

(Comparative Example 1)
By using terephthalic acid as a dicarboxylic acid component, using a polyester resin containing 67 mol% of a component derived from ethylene glycol as a diol component and 33 mol% of a component derived from 1,4-cyclohexanedimethanol, by an extrusion method. A film having a thickness of 45 μm was extruded and used as a shrink label.

(Comparative Example 2)
Styrene-butadiene block copolymer (styrene 75 wt%, butadiene 25 wt%: Vicat softening point 83 ° C., MFR 6.0 g / 10 min) 50 wt%, styrene-butyl acrylate copolymer (styrene 85 wt%, acrylic Using a mixed resin of 15% by weight of butyl acid: 50% by weight of Vicat softening point 70 ° C., MFR 4.0 g / 10 min), a film having a thickness of 45 μm was extruded by an extrusion method, and this was used as a shrink label.

(Comparative Example 3)
As the outer surface layer, terephthalic acid was used as a dicarboxylic acid component, and a polyester resin containing 67 mol% of a component derived from ethylene glycol and 33 mol% of a component derived from 1,4-cyclohexanedimethanol was used as a diol component. .
As an intermediate layer, a styrene-butadiene block copolymer (styrene 75 wt%: butadiene 25 wt%: Vicat softening point 83 ° C.) 50 wt%, styrene-butyl acrylate copolymer (styrene 85 wt%: butyl acrylate 15 wt%) %: Vicat softening point 70 ° C.) 50% by weight mixed resin was used.
Maleic anhydride-modified linear low density polyethylene (LLDPE) was used as the adhesive layer.
Using these resins, a heat-shrinkable multilayer composed of five layers of outer surface layer (6 μm) / adhesive layer (1 μm) / intermediate layer (31 μm) / adhesive layer (1 μm) / outer surface layer (6 μm) by coextrusion. A resin film was extruded and used as a shrink label. In addition, the temperature after the part where each layer joins was 250 degreeC.

(Comparative Example 4)
As the outer surface layer, terephthalic acid was used as a dicarboxylic acid component, and a polyester resin containing 67 mol% of a component derived from ethylene glycol and 33 mol% of a component derived from 1,4-cyclohexanedimethanol was used as a diol component. .
As an intermediate layer, a styrene-butadiene block copolymer (styrene 75 wt%: butadiene 25 wt%: Vicat softening point 83 ° C.) 50 wt%, styrene-butyl acrylate copolymer (styrene 85 wt%: butyl acrylate 15 wt%) %: Vicat softening point 70 ° C.) 50% by weight mixed resin was used.
Using these resins, a heat-shrinkable multilayer resin film having a three-layer structure of an outer surface layer (6 μm) / intermediate layer (33 μm) / outer surface layer (6 μm) was extruded by a coextrusion method, and this was used as a shrink label. In addition, the temperature after the part where each layer joins was 250 degreeC.

(Evaluation)
About the shrink label manufactured in Examples 1-8 and Comparative Examples 1-4, it evaluated by the following method.
The results are shown in Table 1.

(1) Wearability / appearance Both ends of the shrink label were bonded using a mixed solvent of 100 parts by weight of 1,3-dioxolane and 50 parts by weight of cyclohexane, and processed into a cylinder having an inner diameter of 6.5 cm. The obtained cylindrical shrink label was put on a PET bottle having a diameter of 6.5 cm, and was attached by shrinking by blowing hot air at 85 ° C. Each shrink label was previously perforated. The perforations were cut at 0.5 mm and non-cut at 3.0 mm.
After attaching each 100 pieces to a plastic bottle, and further scratching with a nail, the attachment state of the entire shrink label is visually observed around the center seal portion, and the attachment property is determined according to the following criteria. -Appearance was evaluated.
◯: No delamination or wrinkle was observed.
×: Even with one piece, delamination and wrinkles were observed.

(2) 30 PET bottles equipped with low-temperature-resistant shrink labels (those that can be attached without delamination or wrinkles) were dropped from a height of 70 cm while being kept at 4 ° C, and then visually shrinked. The state of the label was observed, and the low temperature resistance was evaluated according to the following criteria.
A: No breakage from the perforation was observed.
×: Even one piece was found to be broken from the perforation.

(3) Cutability at the perforation About 30 PET bottles equipped with a shrink label (that could be attached without delamination or wrinkles), the shrink label was removed by tearing from the perforation by hand. The state at this time was observed, and the heat resistance was evaluated according to the following criteria.
◯: The easy perforation was broken and the shrink label could be removed.
X: Some were hard to remove by hand.

(4) PET bottles equipped with oil-resistant shrink labels (those that can be attached without delamination or wrinkles) After applying cooking oil on 30 shrink labels, visually observe the state of the shrink labels, The oil resistance was evaluated according to the following criteria.
O: No wrinkles or tears were observed on the shrink label.
×: Even with one piece, the shrink label was found to be wrinkled or torn

(5) A layer including an interlayer strength outer surface layer is defined as a release layer, and a layer including an intermediate layer is defined as a layer to be peeled. The strength was measured when these were peeled in a 180 degree direction with a width of 10 mm.

ADVANTAGE OF THE INVENTION According to this invention, the shrink film which uses the multilayer film which is excellent in low temperature resistance, oil resistance, the cut property in a perforation, and an external appearance, and does not peel at the time of mounting | wearing can be provided.

1 Intermediate layer 2 Outer surface layer 3, 3 'Adhesive layer

Claims (4)

A shrink label having a base film made of a heat-shrinkable multilayer resin film composed of an intermediate layer made of polystyrene resin and an outer surface layer made of polyester resin sandwiching the intermediate layer,
The polystyrene resin constituting the intermediate layer is a mixed resin of an aromatic vinyl hydrocarbon-conjugated diene copolymer and an aromatic vinyl hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymer,
The polyester resin constituting the outer surface layer contains a component derived from terephthalic acid as a dicarboxylic acid component,
Aromatic vinyl hydrocarbon in which the intermediate layer and the outer surface layer have at least one functional group selected from the group consisting of a carboxylic acid group, an acid anhydride group, an amino group, an epoxy group, and a hydroxyl group in the molecule. Adhered by an adhesive layer made of a hydrogenated conjugated diene copolymer,
The functional group content in the hydrogenated product of the aromatic vinyl hydrocarbon-conjugated diene copolymer is 0.05 to 5.0% by weight,
The carboxylic acid group constituting the adhesive layer, acid anhydride group, an amino group, having in the molecule at least one functional group selected from the group consisting of an epoxy group and a hydroxyl group, an aromatic vinyl hydrocarbon - conjugated diene copolymer the content of the aromatic vinyl hydrocarbon component in the hydrogenated product of the polymer is 30 to 80 wt%, the thickness of the adhesive layer is characterized <br/> be 0.7~1.5μm Shi Nulink label. Aromatic vinyl hydrocarbon-conjugated diene copolymer having at least one functional group selected from the group consisting of carboxylic acid group, acid anhydride group, amino group, epoxy group and hydroxyl group constituting the adhesive layer in the molecule The hydrogenated product of the blend is maleic anhydride-modified styrene-ethylene / butylene-styrene block copolymer, amine-modified styrene-ethylene / butylene-styrene block copolymer, amine-modified styrene-butadiene / butylene-styrene block copolymer The shrink label according to claim 1, which is a carboxylic acid-modified styrene-butadiene / butylene-styrene block copolymer. The blending amount of the aromatic vinyl hydrocarbon-conjugated diene copolymer in the mixed resin constituting the intermediate layer is 20 to 80% by weight, and the blending amount of the aromatic vinyl hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymer is 20 The shrink label according to claim 1 or 2, characterized in that it is -80% by weight. The polyester resin constituting the outer surface layer contains a component derived from terephthalic acid as a dicarboxylic acid component, and contains a component derived from ethylene glycol and 1,4-cyclohexanedimethanol as a diol component. The shrink label according to claim 1, 2 or 3 .

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