KR101555409B1 - Thermo-shrinkable polyester mono-layer film - Google Patents

Abstract

The present invention relates to a heat-shrinkable polyester-based single layer film, which is excellent in shrinking property and can exhibit a beautiful appearance after printing, so that it can replace a label of a paper material and is easy to peel off using hot water, Shrinkable polyester based single layer film useful as a film for labels capable of contributing to a heat-shrinkable polyester film.

Description

[0001] Thermo-shrinkable polyester mono-layer film [0002]

The present invention relates to a polyester-based single-layer film having heat shrinkage characteristics.

PET bottles and glass bottles have been collected and reused in consideration of environmental requirements and economic feasibility. In case of recycling, the label on which the product name, component name and other patterns are printed and attached in addition to the PET bottle or glass bottle body should be removed and removed. For paper labels that have been used so far, use industrial water to remove them. Specifically, the collected PET bottles or glass bottles are immersed in industrial water containing caustic soda at a temperature of about 80 ° C. to remove the label. As a result, environmental wastewater is generated in the recycling of engineers, and environmental regulations are becoming serious.

Thus, there is an increasing demand for labels of film materials rather than paper labels.

On the other hand, an example of a film that can be used as a label is a polyvinyl chloride-based film, but this is not preferable due to environmental problems such as generation of dioxin upon incineration, so that a polyester-based heat- It has become a means to replace labels.

As a method of applying a polyester-based heat-shrinkable film to a label, a method of printing on a film such as a sticker type or a conventional paper label and sticking it using a water-soluble adhesive may be considered.

Compared to bottles used for general PET bottles or beverages, PET bottles or glass bottles used for the mainstream are often colored due to the mixing of pigments, UV-blocking agents and other additives in order to minimize alteration of contents .

In applying a label of a film material to such a bottle, it is possible to perform back-coating using ink such as white on the back side of the printed label in order to more clearly show the advertising effect. In this case, however, The effect is insignificant and the color of the bottle is projected as it is and the advertising effect is reduced. In this case, two or more back coatings are required, but this is a factor that lowers fairness and productivity.

Further, in the method of adhering the label with the adhesive, since the adhesive is applied by gravure printing or the like preferentially to the bottle, the mark applied with the adhesive is present in the form of a band. In general, paper labels can conceal these adhesive marks, but in the case of conventional heat-shrinkable films, there is little concealability and these markings are imprinted as they are, which reduces the advertising effect.

Accordingly, an object of the present invention is to provide a heat-shrinkable polyester-based single-layer film having excellent printing appearance and excellent hiding power when applied to a label.

The present invention provides a heat-shrinkable polyester-based single-layer film having excellent print appearance and excellent hiding ability when applied to a label application due to coloring of the film itself while maintaining shrinkage.

In one embodiment of the present invention, particles are dispersed on a polyester resin matrix containing a polybutylene terephthalate resin, and the particles are contained in a total amount of 2 to 10% by weight of the film, and the opacity (%) Is 20 to 70%, and the deviation of the opacity (%) is within ± 5% on the average over the entire width of the film roll. When the film is processed in hot water at 90 ° C for 10 seconds, Shrinkage ratio of from 40 to 80%.

In the heat-shrinkable polyester-based single-layer film according to one embodiment of the present invention, the particles may have an average particle diameter of 0.1 to 5 μm.

In the heat-shrinkable polyester-based single-layer film according to one embodiment of the present invention, the particles are titanium oxide and may be contained in an amount of 2 to 10 wt% of the total weight of the film.

The heat-shrinkable polyester-based single-layer film according to one embodiment of the present invention may have a deviation of the shrinkage ratio with respect to the maximum shrinkage direction on the full width of the film roll within a range of an average of ± 5%.

In the heat-shrinkable polyester-based single-layer film according to one embodiment of the present invention, the polyester-based resin matrix may contain at least one selected from the group consisting of terephthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, A dicarboxylic acid component containing at least one dicarboxylic acid such as phthalic acid, naphthalene dicarboxylic acid and diphenyl ether dicarboxylic acid, and a dicarboxylic acid component containing at least one dicarboxylic acid component such as ethylene glycol, neopentyl glycol, propylene glycol, trimethylene glycol, tetramethylene glycol , At least one copolyester selected from copolyesters obtained from a diol component comprising at least one diol such as hexamethylene glycol, diethylene glycol, polyalkylene glycol, 1,4-cyclohexanedimethanol, .

In the heat-shrinkable polyester-based single-layer film according to one embodiment of the present invention, the copolyester contains 80 mol% or more of terephthalic acid unit in the dicarboxylic acid unit and the unit other than ethylene glycol in the diol unit is 14 to 24 Mol%.

In the heat-shrinkable polyester-based single-layer film according to one embodiment of the present invention, the melting point (° C) of the copolyester may be 195 to 215 ° C.

In the heat-shrinkable polyester-based single-layer film according to one embodiment of the present invention, the copolyester may be contained in an amount of 85 to 98 wt% of the total polyester resin excluding the particle content.

In another embodiment of the present invention, there is provided a method for producing a heat-shrinkable polyester film by extruding and stretching a polyester-based resin, comprising the steps of: a step of preparing a polyester having an average particle size of 0.1 to 5 탆 and a polyester having an intrinsic viscosity of at least 0.8 dl / Preparing a particle-containing polyester-based resin masterbatch by compounding a butylene terephthalate resin, the step of preparing a particle-containing polyester-based resin masterbatch so as to include the particles in an amount of 10 to 70% ; Containing polyester masterbatch and a copolyester resin containing 14 to 24 mol% of a unit other than ethylene glycol in the diol unit to produce an unoriented sheet. The step (b) Containing polyester master master batch and a copolyester resin containing 14 to 24 mol% of a unit other than ethylene glycol among the diol units so as to contain the particles in an amount of 10 wt% ; Preheating the extruded polyester-based sheet; And stretching the film in the width direction at 65 to 100 ° C.

In the method for producing a heat-shrinkable polyester-based single-layer film of the present invention, the step of preparing a master batch includes a homopolyester-based polymer having a Melting Point (° C) difference from the copolyester resin within 30 ° C, Mixing; Adding a mixture to a twin-screw extruder or a kneader and melt-kneading the mixture to obtain a homo-polyester homo-polyester master batch. In the step of obtaining a homopolyester master batch containing molten particles, a cooling means is added to the screw of the extruder And controlling the melting temperature.

In the method for producing a heat-shrinkable polyester-based single-layer film of the present invention, the transverse stretching can be performed such that the stretching ratio is 3.5 to 5.0 times.

In the method for producing a heat-shrinkable polyester-based single-layer film of the present invention, the particles in the polyester-based resin masterbatch may be titanium oxide.

The heat-shrinkable polyester film according to the present invention has excellent heat-shrinkability, which is inherent in a shrinkable film, and is excellent in hiding properties when applied to a label due to its color, It is possible to remove the label by using only the hot water, so that the waste water can be prevented from being generated, which is environmentally friendly.

In one embodiment of the present invention, particles are dispersed on a polyester-based resin matrix containing a polybutylene terephthalate resin, the particles are contained in an amount of 2 to 10% by weight of the total weight of the film, and the opacity (% ) Is 20 to 70%, and the deviation of the opacity (%) is within the range of ± 5% over the entire width of the film roll. When the treatment is performed for 10 seconds in hot water at 90 ° C, Wherein the shrinkage ratio of the heat-shrinkable polyester-based single-layer film is 40 to 80%.

In the polyester film according to one embodiment of the present invention, the polyester-based resin matrix includes a polybutylene terephthalate resin. In general, when the shrinkable film is used commercially, the adhesive method in which the shrinkable film is melted with a solvent is used In consideration of such solvent adhesive force, it is preferable that the polyester-based resin matrix includes a polybutylene terephthalate resin.

However, if the content of the polybutylene terephthalate resin in the polyester resin matrix is too low, the adhesive strength of the solvent may drop and the commercial use may be difficult. On the other hand, when the content of the polybutylene terephthalate resin is excessively high, the main shrinking direction (for example, ) May be lowered, and a decrease in mechanical properties (strength, for example) in a direction perpendicular to the main shrinkage direction (for example, machine direction MD) may occur. In general, a film is required to have mechanical properties in the machine direction as it is subjected to many roll processes in commercial use, and when the mechanical properties are poor, breakage or breakage of the film may occur. In view of this point, the polybutylene terephthalate resin may preferably be contained in an amount of 2 to 15% by weight of the total polyester-based resin matrix.

In addition, the heat-shrinkable polyester film according to one embodiment of the present invention has an opacity (%) of 20 to 70%. As described above, in the application to label PET bottles and glass bottles The opacity (%) should be at least 20% or more, and the opacity (%) should be at least 40% in order to have a degree of hiding that can cancel the inherent color. However, if the opacity (%) exceeds 70%, the shrinkage rate can be inhibited because the content of the particles must be excessive.

The opacity (%) was measured on the basis of ASTM D-1003. Seven portions were randomly extracted from two portions of the polyester film and one center portion of the polyester film, and the pieces were cut into 5 cm × 5 cm pieces. The opacity Opacity Meter Series 6000), measuring the opacity (%), and calculating the average value of the five values excluding the maximum value and the minimum value.

The deviation of the opacity (%) should represent a value within the average of ± 5% over the full width of the film roll while satisfying the opacity (%) value as described above. Is less than the entire width of the film roll, it disproves that the dispersion of the particles is optimized.

In the present invention, "the deviation of the opacity (%) over the entire width of the film roll shows a value within an average of ± 5%" means that the specimen is sampled continuously in the size of 5 cm × 5 cm over the entire width of the film, The opacity (%) was measured for each specimen in the same manner as the above opacity (%) measurement method based on ASTM D-1003, and the average value, the maximum value and the minimum value of the entire specimen were determined, And the minimum value has a value within an average value of the full width of the film roll within 占 5%.

The polyester film is inherently transparent. In order to make such a polyester film opaque, a method of applying inorganic particles or inert organic particles may be considered. As an example of the particle addition method, there is a method of polymerizing a polymer containing particles at high concentration by adding particles during the polymer polymerization process . However, in the case of such a method, it is difficult to increase the content of the particles in the polymer to a certain level or more due to the problem of dispersion of the particles during the polymerization process. In other words, it is difficult to show the opacity (%) to the degree described above. Further, since the dispersion is uneven, it may be difficult to show the even opacity (%) value over the full width of the film roll.

Accordingly, in one embodiment of the present invention, particles are separately mixed with the polymer that has been polymerized, and further, by masterbatching the particles, it is possible to maximize the amount of particles that can be contained and to control the particle size, Process control is performed so as to maximize the uniformity of particle sorting, particle dispersion uniformity, and particle content between master batch chips, thereby minimizing the opacity (%) deviation over the entire film roll.

For example, in the heat-shrinkable polyester single-layer film according to one embodiment of the present invention, the particles may have an average particle diameter of 0.1 to 5 μm. When the average particle diameter of the particles is within the above range, it is easy to control the optical property and control the shrinkage ratio.

On the other hand, examples of the inorganic particles that can be added for the purpose of exhibiting color characteristics include barium sulfate, titanium oxide, and silica, and titanium oxide is preferable in terms of good stretchability and light scattering due to particles Do. In the case of barium sulfate, micro-voids are formed in the film during stretching to cause irregular reflection of light so that the film becomes colored. The micro-void formed in the film shrinks the film. The microcavity is lost by the adhesion of the polymer chain in the process, and the color of the film is changed from color to transparency, which is not preferable because it is restricted in terms of application diversity. Further, in the case of silica, the size of the particles is limited, and when a film containing a large amount of particles is produced by using particles having a large particle size, a large amount of large particles protrude from the surface of the film, resulting in poor appearance in printing.

As a result, titanium oxide is the most suitable particle capable of exhibiting coloration while maintaining shrinkage characteristics.

Also, the range of content that can satisfy the characteristics of the shrinkage ratio while controlling the color depending on the particle should be controlled. In the case of titanium oxide, the content of the titanium oxide is 2 to 10% by weight based on the total weight of the film. %) Value while satisfying the shrinkage ratio.

The heat-shrinkable polyester-based single-layer film according to one embodiment of the present invention has a shrinkage ratio of 40 to 80% with respect to the maximum shrinkage direction when treated for 10 seconds in hot water at 90 ° C.

Usually, in the step of shrinking a label or the like made of a heat-shrinkable film to cover a container or the like, hot air having a wind speed of about 2 to 20 m / sec is passed at about 120 to 200 DEG C in a hot air tunnel in about 2 to 20 seconds, To about 95 ° C and a pressure of about 0.5 to 20 MPa for about 2 to 20 seconds.

Considering this point, in one embodiment of the present invention, it is possible to achieve a shrunk appearance which is very good under the shrinkage condition in which the film shrinkage ratio, specifically, the heat shrinkage ratio is within the above range.

Specifically, when the shrinkage ratio with respect to the main shrinkage direction is 40% or less when treated for 10 seconds in hot water at 90 캜, the time required for shrinkage is prolonged, resulting in a decrease in productivity and a high energy cost. It may be difficult to apply it to various types of containers due to its poor applicability due to the high shrinkage rate. On the other hand, when the shrinkage rate to the main shrinkage direction exceeds 80%, the air existing between the container and the label hardly escapes due to an excessively high shrinkage rate An air layer may be formed between the label and the container to deteriorate the appearance of the product.

* Such a range of the heat shrinkage ratio is also obtained by attaching a heat-shrinkable film to a bottle or the like using an adhesive, collecting the bottles, and peeling the label using hot water at the time of recycling, It is also advantageous in terms of allowing the shrink film to easily come out after being curled.

The film satisfying the above conditions can exhibit a variation in the shrinkage ratio with respect to the maximum shrinkage direction within the full width of the film roll within an average of +/- 5%. The shrinkage factor can be evenly distributed over the full width of the film roll, which can also be achieved by uniformly dispersing the added particles in order to develop color.

In the present invention means that the variation of the shrinkage ratio with respect to the maximum shrinkage direction in the full width of the film roll has a value within an average of 5% or less in the longitudinal direction (MD direction) of the film and 15 mm MD direction) x 400 mm (TD direction) were continuously taken, and a vertical line was drawn in the longitudinal direction (MD) of the film at 50 mm at both ends in the TD direction with respect to each specimen to determine the effective length And the maximum shrinkage direction was measured by measuring the shrinkage ratio in the maximum shrinkage direction at 90 ± 0.5 ° C in hot water at 90 ± 0.5 ° C to obtain the average value, It will be appreciated that the maximum and minimum shrinkage rates have values within the mean value +/- 5%.

If the length of the film in the TD direction is less than 400 mm, it is evaluated in the same manner as described above. However, the measured specimen size and the effective length of the shrinkage measurement may be variable.

As described above, the heat-shrinkable polyester film satisfying such physical properties includes not only polybutylene terephthalate resin but also terephthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, , A dicarboxylic acid component containing at least one known dicarboxylic acid such as phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid and the like, and at least one member selected from the group consisting of ethylene glycol, neopentyl glycol, propylene glycol, Among the copolyesters obtained from the diol component containing at least one known diol such as trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, polyalkylene glycol, 1,4-cyclohexanedimethanol and the like, At least one co-polyester.

Wherein the copolyester may be a copolyester wherein the terephthalic acid unit comprises at least 80 mole percent of the dicarboxylic acid unit and the unit other than ethylene glycol comprises at least 14 to 24 mole percent of the diol unit. Among the copolyesters, the units other than the ethylene glycol units have the function of increasing the shrinkage ratio by lowering the crystallinity of the polyester polymer. The proportion of the monomer units falling within the above range is preferable for controlling the drying process, May be advantageous in terms of controlling the melting characteristics and physical properties.

In the present invention, the copolyester itself can be produced by a general production process of a polyester. For example, a direct esterification method in which a diol is directly reacted with a dicarboxylic acid, and an ester exchange method in which a dimethyl ester diol of a dicarboxylic acid acts.

According to an embodiment of the present invention, the copolyester has a Melting Point (占 폚) of 195 to 215 占 폚 and an intrinsic viscosity of 0.60 to 0.70 dl / g. In this case, the melting point (° C) can be controlled according to the composition of the monomers used for preparing the polymer, and the intrinsic viscosity can be changed according to the degree of polymerization. In the present invention, the melting point (° C) And a copolyester having an intrinsic viscosity within the above range can be used.

On the other hand, the heat-shrinkable film is required to run at a high speed or wind it at a high speed in order to improve the productivity in the film-forming step and the post-processing step, The film may include an in-line coating layer containing an antistatic agent on the surface layer.

Herein, the term 'in-line coating layer' will be understood as a layer formed by a coating process in any of the processes of extruding and forming a polyester resin to those having ordinary skill in the art.

When the in-line coating layer including the antistatic agent is formed on the surface layer of the film as described above, the static electricity generated by the friction is relieved, thereby eliminating the phenomenon that the films adhere to each other during the process of winding the film roll, It can be advantageous in that it can facilitate the escape of the introduced air in the process to be taken. In addition, it is possible to prevent defective printing due to static electricity caused by friction between the printing roll and the film during the printing process, and to prevent defective feeding by removing the phenomenon that the film sticks due to static electricity during the post-process .

Examples of the antistatic agent include, but not limited to, quaternary ammonium compounds, alkylsulfonate compounds categorized as RSO ₃ Na, alkylsulfate compounds categorized as ROSO ₃ Na, and alkylphosphate compounds. The content thereof is 0.1 to 1.5% by weight based on the active ingredient in the coating liquid for forming an in-line coating layer, which minimizes the amount of foreign matter generated by friction during the printing process, the tubing process and the heat shrinking process, Lt; / RTI >

On the other hand, the binder resin may be included in the inline coating layer in consideration of binding force and adhesive force. The binder resin is not particularly limited and may be selected in consideration of the solubility of the solvent in the tubing process.

Examples of binder resins that can be considered include polyester-based, acrylic-polyester copolymers, and copolyester-based resins.

The polyester heat shrinkable film of the present invention having the above properties can be produced, for example, by the following production process.

First, a particle master batch is manufactured.

Uniform distribution of the particles in the master batch, the processability of the master batch, the drying processability, and the homogeneous mixture of the master batch and the polymer mixed with each other can be considered in the course of preparing the master batch, , Such properties have the greatest effect on the properties of the polymer used in the masterbatch.

Usually, the polymer used in the particle masterbatch uses the same polymer as the polymer constituting the main matrix of the film, but in the case of a heat shrinkable film, a copolymer is used so that crystallization hardly occurs during the stretching and heat treatment processes Such polymers are very poor in heat resistance. When a master batch is produced using such a copolymer, melting of the copolymer occurs at the feeding portion of the extruder for producing the master batch first, resulting in poor compatibility between the particles and the copolymer, It is difficult to manufacture. In order to produce a film using the master batch, a drying process for removing moisture is required. In this case, the temperature of the drying process, which is usually applied, is about 140 to 160 ° C. When the master batch is dried at such a temperature, It is difficult to dry due to frequent occurrence of lumping due to fusion between the surface of the batch chip and drying for a long time at a low temperature. Thus, various problems such as a change in color of the polymer and a decrease in processability may occur.

Therefore, it is preferable to apply a homopolyester system. In the case of producing a master batch by applying such a homopolyester system, when the melting characteristic of the polymer applied to the master batch is different from the copolymer constituting the main matrix of the film , The master batch and the copolymer are melted and kneaded to produce a film, the kneading property between the master batch and the copolymer tends to be poor, and the uniform dispersibility of the particles in the film is deteriorated. Therefore, the polymer applied to the master batch should not have a large difference in melting point (° C) from the copolymer constituting the main matrix of the film, and the melting point (° C) .

When the melting point difference between the copolymer and the master batch is 30 ° C or more, the viscosity difference of the polymer due to the melting temperature is excessively large, resulting in a problem of kneading property, and the physical properties of the produced film are largely deteriorated.

Thus, in the present invention, it may be desirable to prepare the particle masterbatch using polybutylene terephthalate resin and titanium oxide particles such as those described above, but using polybutylene terephthalate resin In the course of drying the masterbatch, there is no fusion between the surface of the master batch chip, so that it does not cause problems in the drying process, and the melt-kneading property with the copolyester used in the film production is excellent, Because it is excellent.

However, in the production of a masterbatch using polybutylene terephthalate, which is a polymer used in the production of a film, since the glass transition temperature of polybutylene terephthalate is low, It can cause problems.

Thus, in one embodiment of the present invention, a particle masterbatch is prepared in the following manner.

In the method for producing a heat-shrinkable polyester-based single-layer film of the present invention, the step of preparing a master batch includes mixing particles with polybutylene terephthalate; Containing polybutylene terephthalate master batch by adding the mixture into a twin-screw extruder or a kneader and melt-kneading the mixture to obtain a particle-containing polybutylene terephthalate master batch. In the step of obtaining the particle-containing polybutylene terephthalate, a cooling means is provided inside the screw of the extruder Thereby controlling the melting temperature. If the melting temperature is not controlled by adding the cooling means in the step of obtaining the particle-containing polybutylene terephthalate, fusion of chips occurs in the feeding part of the extruder, resulting in poor feedability and poor kneading property with the particles have.

The cooling may be water cooling or air cooling, which may be performed over the entire length of the screw, or only a portion thereof.

In this case, the particles are particles having an average particle diameter of 0.1 to 5 탆 as described above, and the polybutylene terephthalate resin preferably has an intrinsic viscosity of at least 0.8 dl / g in consideration of a decrease in viscosity due to heat generated during the masterbatch manufacturing process can do.

The content of the particles in the master batch may be 10 to 70% by weight, and the maximum value of the particle content in the master batch may be determined in consideration of the uniformity of the particle dispersion in the master batch and the fairness.

In the production of the polyester-based sheet by mixing and extruding the thus obtained particle-containing polyester-based resin masterbatch with the copolymer, the content of the masterbatch is adjusted so as to contain the particles in an amount of 2 to 10% by weight based on the total weight of the film .

Extrusion is extruded at 200 to 350 ° C. Any known method such as a T-die extrusion method or a tubular extrusion method may be used for the extrusion.

The extruded product is rapidly cooled, for example, by uniformly adhering it to a cooling roll in the same manner as the electrostatic contact method to obtain an unstretched film.

Such an unstretched film is preheated through a roller which naturally proceeds in a mechanical direction, and then is stretched in the width direction, followed by heat treatment.

Since the degree of opacity may vary depending on the stretching condition even at the same particle content, it is necessary to control the stretching condition and the heat treatment condition. In other words, the level of opacity (%) expressed according to the stretching condition may be changed. The lower the stretching temperature, the higher the opacity (%) at the same particle content. In this case, , The temperature of the stretching section may be 65 to 100 캜, and the stretching ratio may be preferably 3.5 to 5.0 times.

If the stretching ratio of the shrink film is small, the shrinkage ratio may be lowered. On the other hand, if the stretching ratio is too high, it is difficult to expect breakage or improvement of physical properties. It can be selected within the range of about 5.0 times.

As the stretching method, an ordinary apparatus is used, and known methods such as roll drawing, tenter stretching, tubular stretching and the like can be applied.

After the stretching process, heat treatment is performed at a temperature ranging from room temperature to 100 占 폚.

On the other hand, in order to form the in-line coating layer described above, before the step of preheating the extruded polyester sheet, a step of coating a tank liquid containing an antistatic agent may be carried out and then subjected to a subsequent process.

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

The evaluation method used in the present invention is as follows.

(1) Film intrinsic viscosity (I.V.)

And at a concentration of 0.3 g per 25 ml of ortho-chlorophenol at 35 캜 using a viscometer.

(2) Measurement and definition of melting point (° C)

The polymer is put into liquid nitrogen for 30 seconds, then taken out, and then powdered by using a crusher (Hico-10-6-388), and then put into a capillary tube (2 × 100 mm). The capillary tube is filled with the polymer in the powder state at a height equal to or more than 2/3 of the length of the tube, and placed in a Melting Point measuring instrument (Thomas Hoover Capillary Melting Point Apparatus) min, the temperature at the melting point of the polymer in the capillary tube is determined from the thermometer and defined as Melting Point (Tm).

(3) Heat shrinkage

Cut into a rectangle having a size of 15 mm (MD) x 400 mm (TD) with respect to the longitudinal direction (MD) and the transverse direction (TD) of the film and draw a solid line in the MD direction at both ends in the TD direction, After preparing specimens, the specimens were held in a position no more than 50 mm from one end of the specimen by using tweezers or the like, and the specimens were heat-shrunk for 10 seconds in completely immersed state in hot water at 90 ° C ± 0.5 ° C , The film was allowed to stand at room temperature for 1 minute, and the reduced length at intervals of 300 mm in the TD direction indicated by an initial solid line was measured to determine the heat shrinkage ratio in the film width direction (TD) according to the following formula (1).

<Formula 1>

(4) Shrinkage rate variation

Ten samples were continuously sampled in the longitudinal direction (MD direction) and the width direction of a size of 15 mm (MD direction) × 400 mm (TD direction), and in each TD direction, , A test specimen having an effective measurement length of 300 mm was prepared, and then a point within 50 mm from one end of the specimen was gripped using a tweezers or the like without any distinction between left and right sides, and the entire specimen was placed in an unloaded state at 90 ± 0.5 ° C After shaking for 10 seconds in a fully immersed state, the sample was allowed to stand at room temperature for 1 minute, and the shrinkage rate in the direction of maximum shrinkage was measured by measuring the reduced length at intervals of 300 mm in the TD direction indicated by an initial solid line. The maximum value and the minimum value are obtained, and the difference between the maximum value and the minimum value with respect to the average value is expressed as an absolute value, and a double large value is defined as a shrinkage rate deviation.

<Formula 2>

Shrinkage rate deviation = ┃ Average shrinkage rate - Maximum shrinkage rate (or minimum value) ┃

(5) Opacity (%)

The measurement method was based on ASTM D-1003. Polyester film was randomly extracted from two portions at one location and one portion at a central portion, and then cut into 5 cm × 5 cm pieces. The resulting film was measured with an Opacity Meter Series 6000 And the opacity (%) was calculated by calculating the average value of the five values excluding the maximum value and the minimum value.

(6) Opacity (%) Deviation

The opacity (%) was measured in the same manner as the opacity (%) measurement method based on ASTM D-1003 with respect to each specimen, and the specimen was continuously measured in the size of 5 cm × 5 cm over the entire width of the film. The maximum value and the minimum value of the entire sample are obtained and then the difference between the maximum value and the minimum value with respect to the average value is expressed as an absolute value and a large value is defined as an opacity (%) deviation. Respectively.

<Formula 3>

Opacity Deviation = ┃ Opacity Average - Opacity Maximum (or minimum) ┃

(7) Evaluation of printing appearance

A film roll having a width of 560 mm and a length of 2000 m was printed, and the number of defective prints due to the occurrence of protrusions was measured to evaluate the printing uniformity.

Printing was carried out using a commonly used gravure printing machine, and 6-color printing was carried out in red, blue, yellow, green, black and white colors. Printing defects due to protrusions were caused by defective ink adhesion Circular and elliptical printing halftone dots, and the printing defective rate is the number generated for 2000 m.

 <Formula 4>

Printing defect rate (%) = [number of projections (ea) / 2000 (m)] x 100

(8) Evaluation of peelability after sticking to a bottle with label

A water-soluble adhesive prepared by mixing 45 parts by weight of styrene-butadiene rubber latex, 40 parts by weight of acrylic emulsion, 10 parts by weight of ethylene-vinyl emulsion, 0.8 part by weight of sodium hydroxide, 0.1 part by weight of bactericide and 4.1 parts by weight of water, The film coated with the adhesive was applied to a glass bottle and rubbed back and forth 10 times at a pressure of 3 kg / cm &lt; 2 &gt; with respect to the total area of the film so as to firmly adhere the film to the glass bottle using a rubber roller. And the adhesive was solidified to fix the film firmly to the glass bottle.

The number of bottles in which the film was not completely peeled was measured in a glass bottle after 1,000 glass bottles with film were left in hot water at 80 캜 for 2 minutes, and the peelability was evaluated by the peeling failure rate according to the following formula (5).

&Lt; EMI ID =

&Lt; Example 1 >

(1) 100 mol% of terephthalic acid as a dibasic acid component, 100 mol% of ethylene glycol and 24 mol% of neopentyl glycol as a glycol component, 0.05 mol of antimony trioxide (as acid component) as a catalyst, (Co-PET) having an intrinsic viscosity of 0.67 dl / g and a melting point of 204 ° C was prepared.

(2) A polybutylene terephthalate (PBT) resin was obtained by adding 100 parts by weight of terephthalic acid and 100 parts by weight of 1,4-butanediol as catalyst and 0.015 part by weight of tetrabutyl titanate as a catalyst (intrinsic viscosity of 0.97 dl / g , Melting Point 220 [deg.] C)

(3) On the other hand, a mixture obtained by mixing a polybutylene terephthalate (PBT) resin prepared as described above and particles of titanium oxide particles (particle size: 0.5 m) in a twin-screw extruder or a kneader was melted and kneaded to obtain a polyester- Batch chips were obtained.

At this time, a cooling means for water cooling was provided in the screw of the extruder so that the melting temperature was controlled not to exceed 260 캜, and the content of titanium oxide in the master batch was 50% by weight.

(4) In order to prevent the degradation of the compatibility between the chips due to the difference in specific gravity in supplying the master batch of the copolyester (1) and the master batch of the above (1) to the extruder, a fixed feeder 20% by weight of the master batch was fed based on the total polymer weight.

The two kinds of polymers were melt-kneaded and extruded from an extruder at 280 DEG C, and then rapidly cooled through a cooling roller to obtain a solidified unoriented film.

The undrawn film was passed through an in-line coating (ILC) process through a roller conveyed in a mechanical direction (MD), followed by a stretching at a temperature of 85 ° C at a temperature of 71 ° C and a transverse direction (TD) And then the film was prepared through a heat treatment zone at room temperature.

In the above, inline coating (ILC) was carried out by applying a coating liquid containing 0.4 wt% of an acrylic-polyester copolymer binder and 0.1 wt% of an alkyl phosphate-based antistatic agent based on the active ingredient, to Mayer Bar # 4.

The obtained film is a heat-shrinkable film having a thickness of 50 탆, and physical properties of the film are shown in Table 3.

&Lt; Example 2 >

(4) A mixture of 96 wt% of the co-polyester (Co-PET) of the above (1) and 4 wt% of the polybutylene terephthalate (PBT) resin (2) (3) was supplied through a side feeder at a rate of 20% by weight based on the total weight of the polymer, and the mixed batch was fed through a hopper at the top of the extruder. The properties of the films are shown in Table 3. &lt; tb &gt;&lt; TABLE &gt;

<Example 3-8>

The heat shrinkable film was prepared in the same manner as in Example 1 except that the melting point of the copolyester, the particle size of the master batch chip and the particle content in the film, the stretching temperature in the transverse direction (TD) 1, and the physical properties of the film are shown in Table 3. &lt; tb &gt;&lt; TABLE &gt;

&Lt; Reference Example 1 &

A heat-shrinkable film was prepared in the same manner as in Example 1 except that the melt-temperature control means was not added during the particle master batch production process of (3).

The physical properties of the film are shown in Table 3.

<Reference Example 2>

The heat shrinkable film was prepared in the same manner as in Example 1 except that the copolyester of the above (1) was used instead of the polybutylene terephthalate resin in the preparation of the particle-containing masterbatch, and the particle-containing copolyester was dried , It was used as a stirrer and dried at 120 DEG C for 30 hours while stirring at 10 rpm. The master batch of the above (3) was provided with cooling means in the screw of the extruder so that the melting temperature was controlled not to exceed 260 캜 and the content of titanium oxide in the master batch was made equal to 50% by weight. In supplying the master batch of (4), a side feeder was provided to supply 20% by weight of the master batch based on the total polymer weight.

The physical properties of the film are shown in Table 3.

<Reference Example 3>

A heat shrinkable film was prepared in the same manner as in Example 1 except that the following homopolyester was used in place of the polybutylene terephthalate (PBT) resin of (2) in the preparation of the particle-containing masterbatch.

100 mol% of terephthalic acid as a dibasic acid component and 124 mol% of ethylene glycol as a glycol component and 0.05 mol of antimony trioxide (as acid component) as a catalyst were polycondensed by direct esterification to obtain an intrinsic viscosity of 0.65 dl / g and Homo-PET having a melting point of 256 占 폚 was prepared and used to prepare a master batch.

The particle size and content were the same as in Example 1, and no means for controlling the melting temperature was added during the process of preparing the masterbatch.

It is to be noted that a 20% by weight based on the total weight of the polymer was supplied by supplying a constant amount feeding device (a side feeder) in supplying the master batch of (4) of Example 1.

The physical properties of the film are shown in Table 3.

&Lt; Referential Examples 4 to 7 >

The heat shrinkable films were prepared in the same manner as in Examples 5 to 8 except that the particle content, the TD stretching condition and the size of the master batch particles in the film were changed as shown in Table 2 below.

The physical properties of the film are shown in Table 3.

Contents Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 CO-
PET Ethylene glycol usage
(mole%) 100 100 96 106 100 100 106 102 Neopentyl glycol
Usage (mol%) 24 24 28 18 24 24 18 22 Intrinsic viscosity (dl / g) 0.67 0.67 0.62 0.69 0.67 0.67 0.69 0.68 Melting Point (° C) 204 204 200 208 204 204 208 205 Particle-containing masterbatch Average Particle Size (μm) 0.5 0.5 2.5 0.2 0.5 4.5 0.5 0.5 Particle content (wt%) 50 50 20 60 50 50 10 50 Applied Polymer Type Homo Homo Homo Homo Homo Homo Homo Homo Applicable polymer PBT PBT PBT PBT PBT PBT PBT PBT Intrinsic viscosity of polymer (dl / g) 0.97 0.97 0.97 0.97 0.97 0.85 1.20 0.97 Of applied polymer
Melting Point (° C) 220 220 220 220 220 220 225 220 Mixing ratio of master batch (wt%) 20 20 20 5 7 4 20 7 Whether to use cooling means in the extruder during masterbatch manufacturing ○ ○ ○ ○ ○ ○ ○ ○ Based on total weight of film
Particle content (wt%) 10 10 4 3 3.5 2 2 3.5 MD
Stretching Drawing magnification (%: additional stretching ratio other than natural stretching ratio) 1.003 1.003 1.003 1.005 1.003 1.003 1.050 1.003 TD
Stretching Preheating temperature (℃) 85 85 85 82 88 92 90 93 Stretching temperature (占 폚) 71 71 73 96 72 94 80 69 Drawing magnification (times) 4.1 4.1 4.2 4.1 3.8 4.1 4.5 4.2 Heat treatment temperature (캜) Room temperature Room temperature Room temperature 83 83 94 Room temperature Room temperature

Contents Reference Example 1 Reference Example 2 Reference Example 3 Reference Example 4 Reference Example 5 Reference Example 6 Reference Example 7 CO-
PET Ethylene glycol usage
(mole%) 100 100 100 100 100 106 102 Neopentyl glycol
Usage (mol%) 24 24 24 24 24 18 22 Intrinsic viscosity (dl / g) 0.67 0.67 0.67 0.67 0.67 0.69 0.68 Melting Point (° C) 204 204 204 204 204 208 205 Particle-containing masterbatch Average Particle Size (μm) 0.5 0.5 0.5 0.5 6.0 0.5 0.5 Particle content (wt%) 50 50 50 50 50 30 50 Applied Polymer Type Homo Co Homo Homo Homo Homo Homo Applicable polymer PBT Co-PET PET PBT PBT PBT PBT Intrinsic viscosity of polymer (dl / g) 0.97 0.67 0.65 0.97 0.85 1.20 0.97 Of applied polymer
Melting Point (° C) 220 204 256 220 220 225 220 Mixing ratio of the particle-containing masterbatch (wt%) 20 20 20 25 4 5 7 Whether to use cooling means in the extruder during masterbatch manufacturing × ○ × ○ ○ ○ ○ Based on total weight of film
Particle content (wt%) 10 10 10 12.5 2 1.5 3.5 MD
Stretching Drawing magnification (%: additional stretching ratio other than natural stretching ratio) 1.003 1.003 1.003 1.003 1.003 1.050 1.003 TD
Stretching Preheating temperature (℃) 85 85 85 88 92 90 80 Stretching temperature (占 폚) 71 71 71 72 94 80 102 Drawing magnification (times) 4.1 4.1 4.1 3.8 4.1 4.5 4.2 Heat treatment temperature (캜) Room temperature Room temperature Room temperature 83 94 Room temperature Room temperature

Note) The meaning of "Applied Polymer Type": When the dicarboxylic acid component or the diol component used in polymerizing the polymer used in the preparation of the master batch is polymerized with one kind of dicarboxylic acid and diol, Quot; Homo "and when it contains at least one other dicarboxylic acid component or diol component, it is denoted by" Co ".

Note) "Applicable polymer" means: The name of the polymer used in manufacturing the master batch. (PBT = polybutylene terephthalate, Co-PET = polymer in which neopentyl glycol is copolymerized, PET = polyethylene terephthalate)

Heat shrinkage
(%) Heat shrinkage deviation (%) Opacity
(Opacity;%) Opacity
Deviation(%) Printing defect rate
(%) Peeling failure rate
(%) Example 1 76.2 2.3 63.5 3.0 0 0 Example 2 75.6 2.5 62.2 3.3 0 0 Example 3 78.5 2.6 35.2 2.3 0 0 Example 4 42.3 1.7 30.7 1.5 0 0.3 Example 5 67.8 2.3 33.1 1.7 0 0 Example 6 40.6 2.3 24.5 1.6 0 0.5 Example 7 68.9 3.3 22.8 2.0 0 0 Example 8 74.2 2.1 35.2 1.8 0 0 Reference Example 1 71.8 6.3 58.7 8.5 20.3 0.3 Reference Example 2 70.7 8.7 50.6 11.5 45.7 5.1 Reference Example 3 67.2 7.9 52.3 7.6 36.1 12.4 Reference Example 4 60.5 7.5 63.7 12.8 54.3 1.5 Reference Example 5 40.2 4.1 23.1 3.5 34.5 1.0 Reference Example 6 69.4 3.0 18.5 1.3 0 0 Reference Example 7 38.3 5.4 30.3 6.7 0 16.8

From the results of Table 3, it can be seen that, in the case of Reference Example 1 in which the melting temperature of the extruder was not controlled during the masterbatch manufacturing process, feeding failure occurred in the extruder, The uniformity is lowered so that the film produced by extruding the copolyester and the master batch in a mixed state has poor dispersion of the particles and non-uniformity in stretching, resulting in heat shrinkage deviation, opacity (%) deviation, As a result, the appearance of the film is poor.

In the case of Reference Example 2 in which the copolyester was applied in the production of the masterbatch, a lot of lumping occurred due to fusion of the surface of the master batch chip during the process of drying the masterbatch, so that the productivity of the drying process It was difficult to produce the product at a rate of 50% or less as compared with the embodiment. The unevenness of the chip feeding into the extruder was lowered due to the lumping phenomenon of the master batch chip and the partial uneven drying of the chip The hydrolysis of the polymer was very severe, and the thickness of the film was uneven due to the drop of the die discharge pressure due to the viscosity drop. Such a phenomenon resulted in a large deviation in shrinkage rate and a large deviation in opacity (%). In the case of label printing, many printing defects were caused due to thickness defects, and when the label was removed, unevenness in shrinkage due to uneven shrinkage was caused, And the fairness was deteriorated.

In the case of Reference Example 3 in which homopolyester (PET) having a large melting point difference was used in producing the master batch, a difference in melt viscosity due to the difference in melting point between the copolyester and the particle-containing homopolyester (PET) As a result, the uniform dispersibility of the particles in the film was deteriorated, causing unevenness in thickness due to unevenness in stretching stress, resulting in a large variation in shrinkage rate and opacity (%) deviation, Respectively.

In the case of Reference Example 4 in which the content of the particles in the film was more than the proper level, unevenness in stretching due to excessive particle injection was caused, and the shrinkage rate deviation and opacity (%) deviation were large. The printed appearance was poor.

Further, in the case of Reference Example 6 in which the particle content in the film is lower than a proper level, it is difficult to express the required opacity (%), which is not a problem in printing. As a result, -Coating) must be performed, resulting in poor processability and increased manufacturing costs.

In the case of Reference Example 5 in which a particle-containing master batch chip having a particle size of a proper level or higher was applied, protrusions due to particle bumps during the drawing process were significantly generated due to an excessively large particle size, have.

In Reference Example 7, in which the stretching temperature was excessively high, it was difficult to uniformly stretch the entire width, resulting in poor thickness. As a result, the shrinkage rate deviation and opacity (%) deviation largely occurred and the shrinkage ratio was too low, It can be seen that the peeling defect rate is high and the processability is greatly deteriorated.

Therefore, it is preferable to use a master batch using a homopolyester-based resin having a melting point difference of 30 ° C or less from the copolyester according to the present invention, and to disperse particles dispersed on the resin matrix of the film and have opacity (%) of 20 To 70%, and the deviation of the opacity (%) over the entire width of the film roll shows a value within an average of ± 5%. When the film is processed in hot water at 90 ° C for 10 seconds, the shrinkage ratio Is 40 to 80%, and the deviation of the shrinkage ratio with respect to the maximum shrinkage direction has a value within an average of ± 5%, it is found that the heat shrinkable polyester single layer film has excellent processability, printing appearance and peeling property.

Claims (7)

Based resin matrix comprising a polybutylene terephthalate resin, wherein the particles are dispersed on a polyester-
The particles are comprised between 2 and 10 wt% of the total weight of the film,
The opacity (%) is 20 to 70%, and the deviation of the opacity (%) over the entire width of the film roll has a value within the average of ± 5%
Wherein the film has a shrinkage ratio with respect to the maximum shrinkage direction of 40 to 80% and a shrinkage deviation with respect to the maximum shrinkage direction within an average of 5% or less when the film is treated in hot water at 90 캜 for 10 seconds.
The heat-shrinkable polyester-based single-layer film according to claim 1, wherein the particles have an average particle diameter of 0.1 to 5 탆.
The heat-shrinkable polyester single-layer film according to claim 1, wherein the particles are titanium oxide.
The polyester resin matrix according to claim 1, wherein the polyester resin matrix is selected from the group consisting of terephthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, Such as ethylene glycol, neopentyl glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, polyalkylene glycol, diethylene glycol, triethylene glycol, And at least one copolyester selected from copolyesters obtained from a diol component comprising at least one diol such as ethylene glycol, 1,4-cyclohexane dimethanol.
The thermoplastic resin composition according to claim 4, wherein the copolyester comprises a terephthalic acid unit in a dicarboxylic acid unit content of 80 mol% or more and a diol monomer unit in an amount other than ethylene glycol of 14 to 24 mol% film.
The heat-shrinkable polyester-based single-layer film according to claim 4, wherein the copolyester has a melting point of 195 to 215 ° C.
The heat-shrinkable polyester-based single-layer film according to claim 4, wherein the copolyester is contained in an amount of 85 to 98% by weight of the total polyester resin.