KR102320809B1 - Thermal shrinking polyester based film, Method of manufacturing thereof and Label comprising thereof - Google Patents

Abstract

The present invention relates to a heat-shrinkable polyester film, a method for manufacturing the same, and a label including the same, and more particularly, to a polyester heat-shrinkable film that can use a solvent that is easy to handle without causing an environmental problem and post-processing It is possible to provide sticker labels and seaming labels with excellent fairness and a low defect rate in the final product.

Description

Thermal shrinking polyester based film, method of manufacturing thereof and label comprising thereof

The present invention relates to a heat-shrinkable polyester film having heat-shrinkage properties and uniaxially oriented, a method for producing the same, and a label comprising the same.

In consideration of environmental requirements and economic feasibility, PET and glass bottles are collected and reused. In such recycling, in addition to the PET bottle or glass bottle body, labels with product names, ingredient names, and other patterns printed on them must be separated and removed.

In the case of paper labels that have been mainly used so far, remove them using industrial water. Specifically, the label is removed by immersing the collected PET bottle or glass bottle in industrial water at about 80°C containing caustic soda. As a result, environmental wastewater is generated in recycling empty bottles, and environmental regulations are in full swing. Accordingly, there is an increasing demand for labels made of film material rather than paper labels.

On the other hand, heat-shrinkable films are used for general packaging containers such as plastics or glass bottles, shrink packaging, and shrink labels. As such heat-shrinkable films, PVC, PS, and PET-based heat-shrinkable films are used.

However, heat-shrinkable films made of PS have excellent shrinkage process stability, but are inconvenient to use special inks due to weak chemical resistance, and storage difficulties due to their large natural shrinkage rate at room temperature.

Heat-shrinkable film made of PVC is classified as a subject of environmental regulations, such as generation of hydrogen chloride gas when incinerated.

Accordingly, there is an increasing demand for polyester shrink film that has no environmental problems and has excellent chemical resistance and does not require a separate separation process for recycling. have.

Japanese Patent No. 2781598 discloses a polyester resin prepared including a dicarboxylic acid component containing terephthalic acid and isophthalic acid, but has a problem of using a limited adhesive solvent. Research is urgently needed.

The main object of the present invention is to provide a heat-shrinkable polyester film having excellent adhesion to an easy-to-handle solvent (especially, THF).

Another object of the present invention is to provide a heat-shrinkable polyester film having excellent post-processing processability and a remarkably low defect rate of finished products through ILC treatment of the surface.

The present invention also provides a sticker label and a seaming label made of the heat-shrinkable polyester film.

Accordingly, the present invention as a preferred embodiment, a base film comprising a copolyester resin having a glass transition temperature of 70 to 80 ° C, an intrinsic viscosity of 0.60 to 0.75 dl / g and a molecular weight distribution of 2.0 to 4.0, and the base film A primer coating layer formed on one or both surfaces, wherein the copolyester resin is copolymerized with dicarboxylic acid monomers, isophthalic acid and diol monomers, and the shrinkage rate in the main shrinkage direction measured in hot water at 90° C. is 40 % or more, and to provide a heat-shrinkable polyester film having an adhesive strength of 0.65 to 1Kgf with tetrahydrofuran (THF).

The copolyester resin is characterized in that the dicarboxylic acid monomer and isophthalic acid are copolymerized by including a molar ratio of 85 to 95: 5 to 15.

The dicarboxylic acid monomer is terephthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, and the group consisting of Any one or more selected from

The diol monomer is selected from the group consisting of ethylene glycol, neopentyl glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, polyalkylene glycol, 1,4-cyclohexane dimethanol and these There are two or more types.

The primer coating layer has a thickness of 5 to 50 nm, and a friction coefficient of 0.20 or less.

The primer coating layer includes an acrylic binder and a slip agent.

The primer coating layer contains 150 to 250 parts by weight of a slip agent based on 100 parts by weight of the acrylic binder.

As another preferred embodiment, the present invention comprises the steps of preparing a copolyester resin by mixing a dicarboxylic acid monomer and a diol monomer and then carrying out a polycondensation reaction by adding isophthalic acid (S1); preparing an unstretched sheet by melting the prepared copolyester resin at 255° C. to 280° C. (S2); forming a primer coating layer by coating a primer coating layer composition on one or both surfaces of the unstretched sheet prepared in step S2 (S3); After applying heat to the unstretched sheet on which the primer coating layer is formed, stretching in one direction at a stretching rate of 6 to 10 m/sec at a stretching ratio in the main contraction direction by 4 to 6 times (S4) and stretching in the one direction It is to provide a method of manufacturing a heat-shrinkable polyester film comprising the step (S5) of heat-treating the film at 70 °C to 80 °C.

In the step S1, the copolyester resin is prepared by polycondensation reaction including dicarboxylic acid monomer, isophthalic acid and diol monomer in a molar ratio of 85 to 95: 5 to 15: 100.

The dicarboxylic acid monomer is terephthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, and the group consisting of Any one or more selected from

The diol monomer is selected from the group consisting of ethylene glycol, neopentyl glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, polyalkylene glycol, 1,4-cyclohexane dimethanol and these There are two or more types.

The primer coating layer will have a thickness of 5 to 50 nm.

The primer coating layer composition includes an acrylic binder and a slip agent.

The primer coating layer composition includes 150 to 250 parts by weight of a slip agent based on 100 parts by weight of the acrylic binder.

As another preferred embodiment, the present invention provides a label comprising a polyester film prepared by the above-described manufacturing method.

According to the present invention, it is possible to provide a polyester heat-shrinkable film capable of using a solvent that is easy to handle without causing an environmental problem, and a sticker label and a seaming label having excellent post-processing processability and a low defect rate in the final product. .

Hereinafter, the present invention will be described in more detail.

As an embodiment of the present invention, a base film comprising a copolyester resin having a glass transition temperature of 70° C. to 80° C., an intrinsic viscosity of 0.60 to 0.75 dl/g and a molecular weight distribution of 2.0 to 4.0, and one surface of the base film or a primer coating layer formed on both sides, wherein the copolyester resin is copolymerized including a dicarboxylic acid monomer, isophthalic acid and a diol monomer, and the shrinkage rate in the main shrinkage direction measured in hot water at 90° C. is 40% Above, to provide a heat-shrinkable polyester film having an adhesive strength of 0.65 to 1Kgf with tetrahydrofuran (THF).

The copolyester resin is preferably copolymerized with dicarboxylic acid monomer and isophthalic acid in a molar ratio of 85 to 95: 5 to 15. When the molar ratio of the dicarboxylic acid monomer to isophthalic acid is within the above range, it has the advantage of suppressing the crystallization phenomenon by stretching so that the shrinkage behavior can be easily expressed. In particular, the molar ratio of isophthalic acid is within the above range. If there is, it may have the advantage of improving the adhesion with the solvent by facilitating swelling of the solvent by making the structure of the final film bulky.

The copolyester resin copolymerized in the above molar ratio contains a unit structure derived from isophthalic acid in an amount of 5.0 to 15.0 mol%, preferably 6.0 to 12.5 mol%, 12 mol%, 8 mol%, 3 mol% It may be included in an amount such as. When the content of the unit structure derived from the isophthalic acid is less than 5.0 mol%, it may be difficult to implement sufficient adhesion to the solvent, and when it exceeds 15.0 mol%, it is a pre-crystallization process using a vacuum dryer or hot water between chips. Fusing may occur.

Specifically, in the case of polyester, when moisture is present during the melting process, the molecular weight is rapidly reduced due to hydrolysis and the mechanical properties are weakened. In order to prevent this, a process called drying is performed before melting, and the drying process is divided into pre-crystallization and main drying.

General polyester is a crystalline polymer, and surface crystallization occurs in the pre-crystallization step, so that there is no adhesion phenomenon (interchip fusion) between chips (raw materials). However, in the case of co-polyester, it becomes an amorphous polymer, and when appropriate conditions are not provided in the pre-crystallization step, a fusion phenomenon of sticking between chips occurs. This is also related to the amount of copolymer contained in the raw material. If a certain level of copolymer is included, pre-crystallization can be performed using a vacuum dryer. When the amount of copolymer exceeds a certain level, it is a hot water pre-crystallization system Pre-crystallization may be performed. However, if the amount of the copolymer is too high, surface crystallization does not occur in the pre-crystallization step even if optimal conditions are provided or a separate process is used, making the drying process itself to remove moisture in the chip impossible.

In this regard, the heat-shrinkable polyester film containing the above-described copolyester resin has an adhesive strength with tetrahydrofuran (THF) of 0.65 to 1Kgf, preferably 0.68 to 0.87Kgf, more preferably 0.82 to 0.87Kgf. can

In the case of shrink film, after printing on the fabric, it is made in the form of a sleeve through a process called "seaming". After putting the sleeve on the bottle, it shrinks by the shrinkage rate of the fabric itself while going through a shrinkage tunnel and is fixed to the bottle. In the case of products with high shrinkage stress, when the adhesive strength with the solvent is weak in the process of passing through the shrinkage tunnel, the adhesive part falls off and defects occur. In this respect, when the adhesive force with THF as the solvent is within the above range, it has the effect of preventing the occurrence of defects.

The dicarboxylic acid monomer is terephthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, and the group consisting of and any one or more selected from

The diol monomer is selected from the group consisting of ethylene glycol, neopentyl glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, polyalkylene glycol, 1,4-cyclohexane dimethanol and these Two or more types of being can be mentioned.

The primer coating layer preferably includes an acrylic binder and a slip agent.

As the acrylic binder resin, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl acrylate, n-butyl acrylate (n -butyl acrylate, isobornyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate isopropyl methacrylate, n-propyl methacrylate, tert-butyl methacrylate, n-butyl methacrylate, isobutyl methacrylate (isobutyl methacrylate), cyclohexyl methacrylate, isECOobornyl methacrylate, diethylene glycol monomethyl ether methacrylate, 2-ethylhexyl methacrylate (2-ethylhexyl methacrylate), benzyl methacrylate, 1-naphthylmethyl methacrylate, 2-naphthylmethyl methacrylate, 9-anthryl At least one may be selected from the group consisting of methyl methacrylate (9-anthrylmethyl methacrylate), 1-anthrylmethyl methacrylate, and 2-anthrylmethyl methacrylate, , but not necessarily limited thereto.

The slip agent is any one selected from Stearamidopropyldimethyl-2-hydroxyethyl ammonium nitrate, Steramidopropyldimethyl-2-hydroxyethyl ammonium dihydrogen phosphate, N,N-bis (2-hydroxyethyl)-N-(3-dodecyloxy-2-hydroxypropyl) methyl ammonium methosulfate It may include more than one.

The structure of the compound included in the slip agent is as follows.

<Stearamidopropyldimethyl-2-hydroxyethyl ammonium nitrate>

<Steramidopropyldimethyl-2-hydroxyethyl ammonium dihydrogen phosphate>

<N,N-bis (2-hydroxyethyl)-N-(3-dodecyloxy-2-hydroxypropyl) methyl ammonium methosulfate>

By including the slip agent, slip properties may be imparted, and more preferably, the friction coefficient may have physical properties of 0.2 or less. By providing such slip properties, it is possible to reduce the occurrence of scratches during the post-processing process.

In general, moisture in the air is adsorbed to the surface of the film, which causes two adjacent films to stick together. Due to this phenomenon, when one product is taken out from the packaging state of the final product, the label of the adjacent product is torn, which is called blocking failure. In the present invention, it is possible to prevent blocking failure by including the above-described acrylic binder and slip agent.

The primer coating layer may include 150 to 250 parts by weight of the slip agent, preferably 160 to 210 parts by weight, based on 100 parts by weight of the acrylic binder.

By including the acrylic binder resin and the slip agent, blocking resistance can be improved, and slip property can be imparted. By imparting such slip properties, it is possible to reduce scratches that may be generated during post-processing and to reduce defects in the process. In addition, by applying an excellent acrylic binder in terms of heat and water resistance, the blocking resistance was improved.

If the content of the slip agent is less than 150 parts by weight, there is a problem in that the transfer is not performed and slip properties are deteriorated, and when it exceeds 250 parts by weight, blocking is induced.

The primer coating layer may have a thickness of 5 to 50 nm, preferably 10 to 20 nm. When the thickness of the primer coating layer is within the above range, the coating layer is uniformly formed on the surface of the final film, thereby achieving uniform slip and stable anti-blocking properties. In addition, when the thickness of the primer coating layer is less than 5 nm, the coating uniformity does not come out, and when it exceeds 50 nm, the blocking resistance may be reduced.

The primer coating layer of the present invention including the above-described configuration has a coefficient of friction of 0.20 or less.

The above-described copolyester resin preferably has a glass transition temperature of 70 to 80° C., an intrinsic viscosity of 0.60 to 0.75 dl/g, and a molecular weight distribution of 2.0 to 4.0.

When the glass transition temperature is within the above range, thermal stability is excellent and natural shrinkage does not occur during long-term storage.

When the intrinsic viscosity is within the above range, sufficient entanglement exists between the main polymer chains, so that sufficient mechanical strength and elongation can be realized despite the uniaxial orientation.

When the molecular weight distribution is within the above range, it has the advantage of suppressing the slip between polymer chains to maintain the shrinkage rate in the main shrinkage direction given during film manufacture for a long period of time.

The heat-shrinkable polyester film containing the copolyester resin preferably has a shrinkage ratio in the main shrinkage direction measured in hot water at 90° C. of 40% or more, preferably 55% or more, and more preferably 70% or more. When the shrinkage rate is within the above range, it has the advantage of being applicable to various containers currently in use.

The above-described heat-shrinkable polyester film may be prepared by a method according to the following.

Another embodiment of the present invention comprises the steps of preparing a copolyester resin by mixing a dicarboxylic acid monomer and a diol monomer, and then performing a polycondensation reaction by adding isophthalic acid (S1); Melting the prepared copolyester resin at 255 to 280 ℃ to prepare an unstretched sheet (S2); forming a primer coating layer by coating a primer coating layer composition on one or both surfaces of the unstretched sheet prepared in step S2 (S3); After applying heat to the unstretched sheet on which the primer coating layer is formed, stretching in one direction at a stretching rate of 6 to 10 m/sec at a stretching ratio in the main contraction direction by 4 to 6 times (S4) and the above The film stretched in one direction was heated to 70 to 80°C. It is to provide a method of manufacturing a heat-shrinkable polyester film comprising the step (S5) of heat treatment.

[Step (S1)]

First, a dicarboxylic acid monomer and a diol monomer are mixed, and then isophthalic acid is added to carry out a polycondensation reaction to prepare a copolyester resin.

The copolyester resin is prepared by copolymerizing dicarboxylic acid monomers, isophthalic acid and diol monomers in a molar ratio of 85 to 95: 5 to 15: 100 as a molar ratio of dicarboxylic acid monomer to isophthalic acid to diol monomer. desirable. When the molar ratio of the dicarboxylic acid monomer to the isophthalic acid to the diol monomer is within the above range, it has the advantage of suppressing the crystallization phenomenon caused by stretching so that the shrinkage behavior can be easily expressed, and in particular, the molar ratio of isophthalic acid is If it is within the range, it may have the advantage of improving adhesion with the solvent by facilitating swelling of the solvent by making the structure of the final film bulky.

The dicarboxylic acid monomer is terephthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, and the group consisting of and any one or more selected from

The diol monomer is selected from the group consisting of ethylene glycol, neopentyl glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, polyalkylene glycol, 1,4-cyclohexane dimethanol and these Two or more types of being can be mentioned.

The polycondensation reaction may be carried out by a conventional method widely known in the present invention, which is well-known and detailed description thereof will be omitted.

[Step (S2)]

Then, the prepared copolyester resin is melted at 255 to 280° C. to prepare an unstretched sheet.

If the range of the melting temperature is less than 255 ℃, there is a possibility that incomplete melting may occur, which may cause process problems. Degradation, deterioration of long-term properties, etc. occur, and the die shear pressure is lowered, making it difficult to control the thickness during film manufacturing.

At this time, as a process for manufacturing the sheet, a sheet manufacturing method commonly used in the field to which the present invention belongs may be arbitrarily selected and used, for example, a sheet manufacturing method using a T die, blow manufacturing using a circular die method and the like.

[Step (S3)]

Then, a primer coating layer is formed by coating the primer coating layer composition on one or both surfaces of the prepared unstretched sheet (S2).

The primer coating layer composition includes an acrylic binder and a slip agent.

The acrylic binder resin is the same as described in the above-mentioned primer coating layer.

The slip agent is the same as described for the primer coating layer described above.

The primer coating layer composition may include 150 to 250 parts by weight of the slip agent, preferably 160 to 210 parts by weight, based on 100 parts by weight of the acrylic binder.

Blocking resistance can be improved by including the acrylic binder resin and the slip agent, and slip property can be provided. By imparting such slip properties, it is possible to reduce scratches that may be generated during post-processing and to reduce defects in the process. In addition, by applying an excellent acrylic binder in terms of heat and water resistance, the anti-blocking performance was improved.

When the content of the slip agent is less than 150 parts by weight, the transfer is not performed and slip properties are deteriorated, and when it exceeds 250 parts by weight, blocking may be induced.

The primer coating layer composition according to the present invention may further include a wetting agent in addition to the acrylic binder and the slip agent.

The wetting agent is used to improve coating properties, and silicone-based wetting agents, modified silicone-based wetting agents, etc. can be used. Specifically, for example, QE-5212 by Dow Corning, TEGO WET250 by ENDOBIC, BYK340 by BYKCHEMIE, etc. can be used, but is not limited thereto.

The wetting agent is preferably included in an amount of 20 to 100 parts by weight, preferably 20 to 60 parts by weight, based on 100 parts by weight of the acrylic binder. If the content of the wetting agent is less than 20 parts by weight, the coating appearance is poor due to lack of wetting properties, and if it exceeds 100 parts by weight, coating stains may occur due to impurities such as the wetting agent remaining after the drying process. Through the application of the acrylic binder resin and the slip agent, the blocking resistance can be improved and the slip property can be imparted. By imparting such slip properties, scratches that may occur during post-processing can be reduced, and defects in the process can be reduced. In addition, by applying an acrylic binder with excellent heat and water resistance, the blocking resistance was improved.

The primer coating layer is preferably formed to a thickness of 5 to 50 nm, preferably 10 to 20 nm. When the thickness of the primer coating layer is less than 5 nm, the coating uniformity does not come out, and when it exceeds 50 nm, the blocking resistance may be reduced.

The above-described primer coating layer has a coefficient of friction of 0.20 or less.

At this time, as a process of forming a primer coating layer by coating the primer coating layer composition, a method commonly used in the field to which the present invention belongs can be arbitrarily selected and used, for example, a coating method using an M-bar, a gravure coating method and the like.

[Step (S4)]

Then, after applying heat to the unstretched sheet on which the primer coating layer is formed, the uniaxially oriented heat-shrinkable polyester film is stretched in one direction at a stretching rate of 6 to 10 m/sec at a stretching ratio in the main contraction direction by 4 to 6 times. to manufacture

The process of applying heat to the unstretched sheet on which the primer coating layer is formed is preferably heated to a preheating temperature of 85 to 110° C. and a stretching temperature of 70 to 90° C. to the unstretched sheet on which the primer coating layer is formed. When the range of the preheating and stretching temperature is within the above range, it is possible to obtain an effect of minimizing the stretching stress remaining in the final film by lowering the stretching stress generated during stretching.

When the range of the stretching ratio is within the above range, by controlling the shrinkage rate of the final film by the heat treatment temperature, the shrinkage rate in the main shrinkage direction is physically low and the maximum shrinkage rate that can be physically realized can be obtained. .

[Step (S5)]

Then, the film stretched in one direction is heat-treated at 70 to 80°C.

By applying heat to the film without additional stretching of the stretched film in one direction at 70 to 80° C., some residual stress after stretching generated in the stretching section is relieved and crystallization is increased to produce a uniaxially oriented heat-shrinkable polyester film do.

When the heat treatment temperature is within the above range, it has a relatively low residual stress and structurally has a certain level of crystallization, thereby improving resistance to changes in appearance over time, thereby solving the problem of deterioration of the appearance of the film even after long-term storage.

As another preferred embodiment, the present invention provides a label comprising a polyester film prepared by the above-described manufacturing method. The label is preferably a sticker label and a seaming label.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention in more detail, and it will be apparent to those of ordinary skill in the art to which the present invention pertains that the scope of the present invention is not limited by these examples.

Example 1

88 moles of terephthalic acid (TPA), 84 moles of ethylene glycol (EG), and 16 moles of neopentyl glycol (NPG) were mixed and put into the reaction tube, and 12 moles of isophthalic acid (IPA) were put into the reaction tube and 1.5 kg After pressurizing at /cm 2 , the reaction was carried out while raising the temperature to 240° C. while removing by-products. After the esterification reaction, antimony trioxide as a polymerization catalyst in a content of 0.05 mol, magnesium and sodium as a pinning agent in a content of 200 ppm, and polymerization at 280 ° C. for 250 minutes, the glass transition temperature is 71 ° C, and the intrinsic viscosity is 0.71 dl/ g, DEG 1.3wt%, carboxyl terminal group 28.3meq/kg, molecular weight distribution 3.2, the content of the unit structure derived from isophthalic acid (hereinafter referred to as IPA content) was 12 mol% copolyester resin was prepared .

The prepared copolyester resin was melted in ETR heated to 260° C., and an unstretched sheet was prepared using a T-die. On one surface of the prepared unstretched sheet, 200 parts by weight of a slip agent (Stearamidopropyldimethyl-2-hydroxyethyl ammonium nitrate) based on 100 parts by weight of an acrylic binder (PK-8012P, Nippon Carbibe), a silicone-based wetting agent (polyester siloxane) as a wetting agent Copolymer QE-5212, Dow Coatings) 50 parts by weight of a primer coating layer composition mixed with M-Bar was coated to form a primer coating layer having a thickness of 20 nm.

The unstretched sheet having a primer coating layer formed on the one surface was preheated to 95° C., the stretching temperature was heated to 83° C., and then stretched to 4.0 times the width direction at a stretching speed of 8 m/sec. Then, heat treatment at 75° C. to uniaxial An oriented heat-shrinkable polyester film was prepared.

Example 2

92 moles of terephthalic acid (TPA), 84 moles of ethylene glycol (EG), and 16 moles of neopentyl glycol (NPG) were mixed and put into a reaction tube, and 8 moles of isophthalic acid (IPA) were applied. A heat-shrinkable polyester film was prepared in the same manner.

At this time, the prepared copolyester resin had a glass transition temperature of 73° C., an intrinsic viscosity of 0.70 dl/g, a DEG of 1.8 wt%, a carboxyl terminal group of 26.7 meq/kg, a molecular weight distribution of 3.0, and an IPA content of 8 mol. % of the copolyester resin was prepared.

Example 3

A heat-shrinkable polyester film was prepared in the same manner as in Example 1, except that the preheating temperature was 87° C. for stretching the film, and the stretching temperature was heated to 85° C., and the stretching speed was 10 m/sec.

At this time, the prepared copolyester resin had a glass transition temperature of 71° C., an intrinsic viscosity of 0.71 dl/g, a DEG of 1.5 wt%, a carboxyl terminal group of 25.8 meq/kg, a molecular weight distribution of 3.3, and an IPA content of 12 moles. % of the copolyester resin was prepared.

Example 4

95 mol of terephthalic acid (TPA), 84 mol of ethylene glycol (EG), and 16 mol of neopentyl glycol (NPG) were mixed in the reaction tube and added to the reaction tube, except that 5 mol of isophthalic acid (IPA) was applied. A heat-shrinkable polyester film was prepared in the same manner.

At this time, the prepared copolyester resin had a glass transition temperature of 75° C., an intrinsic viscosity of 0.71 dl/g, DEG 1.41 wt%, a carboxyl terminal group of 29.3 meq/kg, a molecular weight distribution of 2.8, and an IPA content of 5 mol%. A phosphorus copolyester resin was prepared.

Example 5

A heat-shrinkable polyester film was prepared in the same manner as in Example 1, except that the stretching temperature of the unstretched sheet was applied at 67°C.

At this time, the prepared copolyester resin had a glass transition temperature of 71° C., an intrinsic viscosity of 0.70 dl/g, DEG 1.42 wt%, a carboxyl terminal group of 27.3 meq/kg, a molecular weight distribution of 3.1, and an IPA content of 12 mol. % of the copolyester resin was prepared.

Comparative Example 1

100 mol of terephthalic acid (TPA), 84 mol of ethylene glycol (EG) and 16 mol of neopentyl glycol (NPG) were mixed and put into a polymerization reaction tube, pressurized at 1.5 kg/cm 2 , and removed at 240° C. A heat-shrinkable polyester film was prepared in the same manner as in Example 1, except that the copolyester was prepared by reacting while raising the temperature to .

At this time, the prepared copolyester resin had a glass transition temperature of 78° C., an intrinsic viscosity of 0.70 dl/g, DEG 1.33 wt%, a carboxyl terminal group of 28.5 meq/kg, a molecular weight distribution of 3.1, and an IPA content of 0 mol%. A phosphorus copolyester resin was prepared.

Comparative Example 2

98.5 mol of terephthalic acid (TPA), 84 mol of ethylene glycol (EG), and 16 mol of neopentyl glycol (NPG) were mixed in the reaction tube, and 1.5 mol of isophthalic acid (IPA) was applied, except that 1.5 mol was applied. A heat-shrinkable polyester film was prepared in the same manner.

At this time, the prepared copolyester resin had a glass transition temperature of 77° C., an intrinsic viscosity of 0.71 dl/g, DEG 1.41 wt%, a carboxyl terminal group of 29.1 meq/kg, a molecular weight distribution of 2.9, and an IPA content of 1.5 mol%. A phosphorus copolyester resin was prepared.

Comparative Example 3

80 mol of terephthalic acid (TPA), 84 mol of ethylene glycol (EG), and 16 mol of neopentyl glycol (NPG) were mixed in the reaction tube and added to the reaction tube, except that 20 mol of isophthalic acid (IPA) was applied. A heat-shrinkable polyester film was prepared in the same manner.

At this time, the prepared copolyester resin had a glass transition temperature of 67° C., an intrinsic viscosity of 0.70 dl/g, DEG 1.42 wt%, a carboxyl terminal group of 27.6 meq/kg, and an IPA content of 20 mol%. A resin was prepared.

Comparative Example 4

A heat-shrinkable polyester film was prepared in the same manner as in Example 1, except that a primer coating layer was not formed on the unstretched sheet.

At this time, the prepared copolyester resin had a glass transition temperature of 71° C., an intrinsic viscosity of 0.69 dl/g, a DEG of 1.5 wt%, a carboxyl terminal group of 28.5 meq/kg, a molecular weight distribution of 3.1, and an IPA content of 12 moles. % of the copolyester resin was prepared.

Comparative Example 5

A heat-shrinkable polyester film was prepared in the same manner as in Example 1, except that a heat treatment process was not applied after the unstretched sheet was uniaxially stretched.

At this time, the prepared copolyester resin had a glass transition temperature of 72° C., an intrinsic viscosity of 0.70 dl/g, a DEG of 1.6 wt%, a carboxyl terminal group of 26.9 meq/kg, a molecular weight distribution of 2.9, and an IPA content of 12 mol. % of the copolyester resin was prepared.

Comparative Example 6

After the unstretched sheet was uniaxially stretched, a heat-shrinkable polyester film was prepared in the same manner as in Example 1, except that the heat treatment process temperature was applied at 85°C.

At this time, the prepared copolyester resin had a glass transition temperature of 71° C., an intrinsic viscosity of 0.69 dl/g, a DEG of 1.5 wt%, a carboxyl terminal group of 26.3 meq/kg, a molecular weight distribution of 3.0, and an IPA content of 12 mol. % of the copolyester resin was prepared.

Comparative Example 7

85 moles of terephthalic acid (TPA), 60 moles of ethylene glycol (EG), and 20 moles of neopentyl glycol (NPG) were mixed and put into a reaction tube, and 15 moles of isophthalic acid (IPA) and 20 moles of diethylene glycol (DEG) were mixed. A heat-shrinkable polyester film was prepared in the same manner as in Example 1, except that the mole was applied.

At this time, the prepared copolyester resin had a glass transition temperature of 61° C., an intrinsic viscosity of 0.69 dl/g, DEG 21wt%, a carboxyl terminal group of 27.6 meq/kg, and an IPA content of 15 mol%. was prepared.

<Characteristic evaluation method>

(1) Measurement of shrinkage

Cut into a rectangle with a size of 15 mm (MD) × 400 mm (TD) in the longitudinal direction (MD) and width direction (TD) of the film, and draw a solid line in the MD direction at both ends of the TD direction at 50 mm, so that the effective measurement length is 300 mm. After making the specimen, hold a point within 50 mm of one end of the sample without distinction between left and right using tweezers, place the entire sample in a no-load state in hot water at 70°C and 90°C, and heat-shrink for 10 seconds in a completely immersed state. , after standing at room temperature for 1 minute, the reduced length of the 300 mm interval in the TD direction indicated by the initial solid line was measured to obtain the 70 ° C and 90 ° C heat shrinkage in the film width direction (TD) according to Equation 1 below.

<Equation 1>

(2) Measurement of adhesion with solvent

Two identical specimens were prepared as films prepared according to Examples and Comparative Examples, respectively. After selecting any one of the prepared specimens and applying tetrahydrofuran (THF) as an adhesive solvent to one surface of the selected specimen in a thickness of 0.5 cm in the vertical direction in the main shrinkage direction, one surface of the other specimen The THF-coated surface of the THF-coated specimen was attached to each other, and the adhesive strength was evaluated with an Instron equipment after being left for one day. At this time, any one of the one surface of the other specimen and the surface to which THF is applied is used as a primer coating layer.

During evaluation, the specimen was cut to 15 mm in width and 100 mm in length, loaded in the main shrinkage direction, and then the adhesive strength was evaluated by applying a head speed of 300 mm/min and a gap of 30 mm.

(3) Measurement of shrinkage stress

The shrinkage stress according to temperature and the shrinkage stress according to time at constant temperature were compared with Kanebo and Testlite devices.

(4) Shooting fairness measurement

Using a label shooting machine (high-speed shrink labeler (SH-5100-S), Saehan Tech Co., Ltd.) used in the field to which the present invention belongs, a label using the prepared film is shot on 100 bottles and the position of the label after shooting was confirmed and compared to the number of seats seated in a predetermined position.

(5) Measurement of blocking resistance

Using heat-gradient equipment (Heat Gradient Tester, TOYOSEIKI), the appearance of tears or stains was compared after treatment through sticky evaluation and heat and water resistance evaluation in the following way.

-In the state of loading two sheets of film, the film is pressed with constant pressure and temperature. After a certain period of time, the film is taken out and the attached side is observed to evaluate the blocking properties. In the case of heat-resistant water, it is a qualitative evaluation method that puts boiling water in an actual bottle, binds the two bottles tightly, and checks whether the label is damaged over time.

The exterior is indicated by the following symbols.

(double-circle): No stickiness. No staining

○: No sticking. mild staining

△: generation of weak adhesion, generation of strong stains

X: strong adhesion, strong staining

The physical properties measured by the above-described method are shown in Tables 1 and 2 below.

(6) Measurement of wrinkle generation during acceleration

The prepared film is packaged in a roll state, put in an aging room set at 40°C, and aged for 1 week. It is a qualitative evaluation method that confirms the occurrence of wrinkles observed visually after unwinding 5m in a roll state after the period has elapsed, applying a certain tension and stretching it.

The exterior is indicated by the following symbols.

(circle): No wrinkle generation.

(triangle|delta): generation|occurrence|production of weak wrinkles. No problems with post-processing.

X: A strong wrinkle occurred. Post-process not available

(7) Measurement of intrinsic viscosity

After melting the film with OCP (Ortho Chloro Phenol) at 160±2℃, measuring the sample viscosity in the viscosity tube using an automatic viscometer (Skyvis-4000) at 25℃. (intrinsic viscosity, IV) was obtained.

[Formula 2]

Intrinsic Viscosity(IV) = {(0.0242×Rel)+0.2634}×F

In Equation 2, a standard chip means a chip selected by a conventional method without an intention to select a specific chip when a single chip is selected from a group of countless chips. In addition, the measurement by standard operation means that the experimenter measured and proceeded according to a conventional method without a specific intention to derive a predetermined result value.

(8) Glass transition temperature measurement

The film was cut to a predetermined size and heat flow was measured using a differential scanning calorimeter (TA Instruments, Q20) at a temperature increase rate of 20°C per minute from room temperature to 280°C. The temperature of the endothermic peak was confirmed among the heat flows, and the temperature of the corresponding peak was used as the glass transition temperature.

(9) Molecular weight distribution measurement

After dissolving 25 mg of sample in 0.5 mL HFIP, dilute 9.5 mL of Eluent. 5 mg of the standard is dissolved in 0.25 mL of HFIP and then diluted in 4.75 mL of Eluent. After adjusting the zero point in GPC (Youngrin, GPC AutoChro), which is a measuring instrument, using the standard, the diluted sample is put into the instrument for measurement. For the measurement, use μStyragel 10 ³ + 10 ⁴ + 10 ⁵ A and keep the flow rate at 1.0mL/min and 40℃.

The physical properties measured by the above-described method are shown in Tables 1 and 2 below.

THF Adhesion
(Kgf) shrinkage stress
(Kg/㎟) shooting fairness
(Ea.) Blocking resistance coefficient of friction Example 1 0.87 1.32 100 ◎ 0.18 Example 2 0.82 1.23 99 ◎ 0.20 Example 3 0.82 1.19 100 ◎ 0.18 Example 4 0.68 1.29 100 ◎ 0.19 Example 5 0.85 1.55 100 ◎ 0.18 Comparative Example 1 0.57 1.52 100 ◎ 0.17 Comparative Example 2 0.62 1.38 98 ◎ 0.18 Comparative Example 3 Unable to manufacture film Comparative Example 4 0.84 1.33 76 X 0.45 Comparative Example 5 0.92 1.62 99 ◎ 0.19 Comparative Example 6 0.55 1.09 100 ◎ 0.20 Comparative Example 7 1.32 1.02 86 ◎ 0.19

70℃ heat shrinkage (%) 90℃ heat shrinkage (%) Wrinkles caused by acceleration Example 1 24 76 ○ Example 2 25 75 ○ Example 3 27 75 ○ Example 4 26 75 ○ Example 5 47 76 ○ Comparative Example 1 25 76 ○ Comparative Example 2 25 75 ○ Comparative Example 3 Unable to manufacture film Comparative Example 4 25 75 ○ Comparative Example 5 26 76 X Comparative Example 6 25 75 ○ Comparative Example 7 38 77 X

As shown in Tables 1 and 2, Examples 1 to 4 make the structure of the final film bulky and relieve some of the residual stress in the film, thereby improving the adhesion of THF and providing stability over time. However, it was found that there was no problem in the post-process. In particular, in the case of Example 3, since the shrinkage stress is lower than that of Examples 1 and 2, it can be applied not only to a hard container but also to a relatively soft PE bottle, so that its use can be wider. In addition, in the case of Example 4, the adhesive force is somewhat weaker than in Examples 1 to 3, and thus may be applied differently depending on the shape of the container. In addition, Example 5 has a high shrinkage rate measured in hot water at 70°C, so that it can be used in a shrinkage process using steam.

However, the heat-shrinkable polyester film prepared according to Comparative Examples 1 and 2 had lower adhesive strength with THF, making it impossible to manufacture a label through a seaming process. Stability is lowered and wrinkles occur over time due to natural shrinkage. In the case of Comparative Example 4, it was found that the application was not possible due to poor shooting processability due to not being subjected to surface treatment through surface coating. In the case of the shrinkage process, steam or hot air is used. When steam is used, the shrinkage rate at 70°C is not important, but when hot air is used, the appearance quality after shrinkage is different depending on the shrinkage rate. In the industry to which the present invention pertains, it is known that the slower the shrinkage rate, the better the appearance quality after shrinkage. Numerical change occurs due to residual stress, and wrinkles are generated on the surface by the numerical change. If wrinkles occur on the film, defects occur in the printing process and seaming process, making it unusable. In the case of Comparative Example 6, crystallization of the film increases due to excessive heat treatment, and due to this, the swelling phenomenon of THF is reduced, so that the adhesion property with THF is deteriorated, making it impossible to manufacture a sleeve. In the case of Comparative Example 7, the adhesive strength is very high as an excessive copolymer is applied, but permeation of the adhesive solvent occurs, and adhesion between labels occurs in the final label, resulting in deterioration of shooting fairness as well as dimensional stability due to very low Tg. Wrinkles occur over time due to natural shrinkage.

All simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (15)

A base film comprising a copolyester resin having a glass transition temperature of 70 to 80 ° C., an intrinsic viscosity of 0.60 to 0.75 dl/g and a molecular weight distribution of 2.0 to 4.0, and a primer coating layer formed on one or both sides of the base film,
The copolyester resin is a copolymer comprising a dicarboxylic acid monomer, isophthalic acid and a diol monomer,
The shrinkage in the main shrinkage direction measured in hot water at 90° C. is 40% or more, and the adhesive force with tetrahydrofuran (THF) is 0.65 to 1Kgf,
The copolyester resin is a copolymer comprising a dicarboxylic acid monomer and isophthalic acid in a molar ratio of 85 to 95: 5 to 15,
The primer coating layer is a heat-shrinkable polyester film comprising 150 to 250 parts by weight of a slip agent based on 100 parts by weight of the acrylic binder. delete According to claim 1, wherein the dicarboxylic acid monomer is terephthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxyl Heat-shrinkable polyester film, characterized in that at least one selected from the group consisting of acids and these. According to claim 1, wherein the diol monomer is ethylene glycol, neopentyl glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, polyalkylene glycol, 1,4-cyclohexane dimethanol and Heat-shrinkable polyester film, characterized in that at least two types selected from the group consisting of these. The heat-shrinkable polyester film according to claim 1, wherein the primer coating layer has a thickness of 5 to 50 nm and a coefficient of friction of 0.20 or less. delete delete After mixing the dicarboxylic acid monomer and the diol monomer, isophthalic acid is added to the polycondensation reaction to prepare a copolyester resin (S1);
Melting the prepared copolyester resin at 255 to 280 ℃ to prepare an unstretched sheet (S2);
forming a primer coating layer by coating a primer coating layer composition on one or both surfaces of the unstretched sheet prepared in step S2 (S3);
After applying heat to the unstretched sheet on which the primer coating layer is formed, stretching in one direction at a stretching rate of 6 to 10 m/sec at a stretching ratio in the main contraction direction by 4 to 6 times (S4); and
Including the step (S5) of heat-treating the film stretched in one direction at 70 to 80 ℃,
In step S1, the copolyester resin is prepared by polycondensation reaction including dicarboxylic acid monomer, isophthalic acid and diol monomer in a molar ratio of 85 to 95: 5 to 15: 100,
The primer coating layer composition is a method of manufacturing a heat-shrinkable polyester film comprising 150 to 250 parts by weight of a slip agent based on 100 parts by weight of the acrylic binder. delete According to claim 8, wherein the dicarboxylic acid monomer is terephthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxyl A method for producing a heat-shrinkable polyester film, characterized in that at least one selected from the group consisting of acids and these. 9. The method of claim 8, wherein the diol monomer is ethylene glycol, neopentyl glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, polyalkylene glycol, 1,4-cyclohexane dimethanol and A method for producing a heat-shrinkable polyester film, characterized in that at least two selected from the group consisting of these. The method of claim 8, wherein the primer coating layer is formed to a thickness of 5 to 50 nm. delete delete A label comprising the heat-shrinkable polyester film of any one of claims 1, 3 to 5.