KR20090077219A - Heat Shrinkable Polyester Film - Google Patents

Abstract

The present invention relates to a heat-shrinkable polyester film, and more particularly, shows excellent shrinkage completeness that hardly causes wrinkles, shrinkage stains, deformations and shrinkage shortages due to heat shrinkage, and exhibits low reduction of low-temperature shrinkage rate and stability after printing. The invention relates to a heat shrinkable polyester film which is excellent for full labeling of bottles, in particular for full labeling of PET bottles and glass bottles. To this end, the heat-shrinkable polyester film according to the present invention is a copolymerized polyester composition in which a first component of terephthalic acid and a second component of a diol composed of ethylene glycol and 1,4-cyclohexanedimethanol are copolymerized. It is characterized by containing -95 weight% and 5-20 weight% of polybutylene terephthalate polymers.

Description

Heat Shrinkable Polyester Film {HEAT SHRINKABLE POLYESTER FILM}

1 is a diagram illustrating an upper curl phenomenon caused by time-dependent change after printing of a heat-shrinkable polyester film

<Brief description of symbols for the main parts of the drawings>

1: Upper curl phenomenon

The present invention relates to a heat-shrinkable polyester film, and more particularly, shows excellent shrinkage completeness that hardly causes wrinkles, shrinkage stains, deformations and shrinkage shortages due to heat shrinkage, and exhibits low reduction of low-temperature shrinkage rate and stability after printing. The invention relates to a heat shrinkable polyester film which is excellent for full labeling of bottles, in particular for full labeling of PET bottles and glass bottles.

In general, a film such as polyvinyl chloride or polystyrene is mainly used as a heat shrinkable film, particularly a heat shrinkable film for labeling a body part of a bottle. However, in the case of polyvinyl chloride film, the difficulty of printing is a serious problem, and in the case of polystyrene film, the generation of chlorine gas at the time of incineration has been a serious problem. In addition, when the PET bottle is recovered and recycled, a label made of a resin other than PET such as polyvinyl chloride or polystyrene should be separated from the bottle. For this reason, the heat-shrinkable polyester film without such a problem attracts considerable attention.

In addition, in the recycling of PET bottles, since the coloring bottles are unsuitable for recycling, alternatives have been considered recently. Among them, there is a method of shrinking the colored label throughout the bottle using a non-colored bottle.

However, when used for the full label of the bottle, the shape of the bottle becomes very variously complicated, so there is a problem in shrinkage completion as a conventional heat shrinkable film. In particular, in the case of a full label of a bottle with a narrow inlet, such as a beverage bottle having a large diameter difference between the body and the inlet, the conventional heat-shrinkable film may cause a shortage of shrinkage at the top of the bottle. The heat shrinkable film used for full labeling of such bottles requires heat shrinkage properties such as high shrinkage. In addition, the conventional heat-shrinkable film may exhibit poor shrinkage after printing due to low temperature shrinkage rate during storage before shrinkage, requiring change of shrinkage completion conditions, or in some cases, poor shrinkage.

Thus, in the case of the full label use of a bottle, there existed a problem that performance was inadequate as a conventional heat shrinkable polyester film.

The present invention has been made to solve the above problems, the object of the present invention is to show excellent shrinkage completeness that hardly occurs wrinkles, shrinkage stains, deformation and shrinkage due to heat shrinkage exhibits low reduction of low-temperature shrinkage rate printing It is to provide a heat shrinkable polyester film excellent after aging stability.

The above and other objects and advantages of the present invention will become more apparent from the following description of the preferred embodiments with reference to the accompanying drawings.

Heat-shrinkable polyester film according to the present invention for achieving the above object is a copolyester composition, the first component of the dicarboxylic acid and the second component of the diol consisting of ethylene glycol and 1,4-cyclohexanedimethanol 80 to 95% by weight of the copolymerized copolymerized polyester composition and 5 to 20% by weight of the polybutylene terephthalate polymer.

Preferably, the heat shrinkage rate of the heat-shrinkable polyester film is 35 to 60% in the main shrinkage direction after 10 seconds in hot water at 75 ° C, 70 ~ 70 in the main shrinkage direction after 10 seconds in hot water at 90 ° C 95%, after treatment for 10 seconds in 90 ℃ hot water, 5% or less in the direction orthogonal to the main shrinkage direction, and after 45 days storage at 35 ℃ or less after 10 seconds treatment in 75 ℃ hot water It is characterized in that more than 40% of the heat shrinkage in the main shrinkage direction.

Preferably, the heat-shrinkable polyester film is characterized in that the thickness distribution is 3% or less.

Also preferably, the unstretched film of the heat-shrinkable polyester film is characterized by being stretched at a temperature of at least Tg ° C and less than Tg + 15 ° C.

Further, preferably, the unstretched film of the heat-shrinkable polyester film has a heat transfer coefficient of 0.0013 cal / cm 2 sec. ° C (0.0054 J / cm 2 sec.k) or less in the preheating step performed before the stretching step. In the stretching process, the heat transfer coefficient of 0.0009 cal / cm 2 sec. ℃ (0.0037 J / cm 2 sec. K) or more.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. These examples are only presented by way of example only to more specifically describe the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples. .

The heat shrinkable polyester film according to the present invention contains a copolyester composition and a polybutylene terephthalate polymer.

The heat-shrinkable polyester film according to the present invention comprises 80 to 95% by weight of a copolymerized polyester composition in which a first component of a dicarboxylic acid component and a second component of a diol consisting of ethylene glycol and 1,4-cyclohexanedimethanol are copolymerized; The polybutylene terephthalate polymer is contained 5 to 20% by weight, most preferably 5 to 10% by weight. If the polybutylene terephthalate polymer is more than 20% by weight it is difficult to obtain the shrinkage necessary to adhere the heat-shrinkable film to the container is not preferable, and if the content of the polybutylene terephthalate polymer is less than 5% by weight the heat-shrinkable film is It is not preferable because the low temperature shrinkage rate is less likely to be expressed, and the shrinkage rate is easily increased, and thus the shrinkage completeness tends to be inferior, such as wrinkles and deformation during shrinkage.

As the dicarboxylic acid component constituting the polyester used in the present invention, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and orthophthalic acid, adipic acid, azeline acid and sebacic acid and decandicar Aliphatic dicarboxylic acids, such as an acid, aliphatic dicarboxylic acid, etc. are mentioned, Especially terephthalic acid is preferable. However, in the case of a heat shrinkable polyester film obtained by using a polyester containing polyester trivalent or higher polyhydric carboxylic acid, it may be difficult to achieve the required high shrinkage.

Moreover, as a diol component which comprises the polyester used by this invention, aliphatic diols, such as aliphatic diol 1, 4- cyclohexane dimethanol, such as ethylene glycol, propanediol, butanediol, neopentylglycol, hexanediol, aromatic diol, etc. are mentioned. I can lift it.

In addition, the polyester used in the heat-shrinkable polyester film according to the present invention contains at least one of diols having 3 to 6 carbon atoms (for example, propanediol, butanediol, neopentylglycol, hexanediol, etc.) Polyester which adjusted Tg) to 60-75 degreeC is preferable. In particular, it is preferable to use 1,4 cyclohexane dimethanol as one kind of diol component for the heat shrinkable polyester film which shows the outstanding shrinkage completeness.

It is preferable that polyester does not contain C8 or more diols (for example, octanediol etc.) or trivalent or more polyhydric alcohols (for example, trimethylol propane, trimethylol ethane, glycerin, diglycerine, etc.). It is because it is difficult to achieve the required high shrinkage rate as a heat-shrinkable polyester film obtained using such a polyester containing diol or polyhydric alcohol.

Diethylene glycol, triethylene glycol and polyethylene glycol are preferably not contained as much as possible. In particular, diethylene glycol can be easily produced as a byproduct component in polyester polymerization.

In addition, when two or more polyesters are mixed and used, the content of the acid component and diol component of the present invention is relative to the total content of all acid components and the total content of all diol components in these polyesters and is transesterified after mixing. It doesn't matter if this can be done.

Moreover, in order to improve the lubricity of the heat-shrinkable polyester film which concerns on this invention, it is also preferable to contain inorganic lubricants, such as titanium dioxide, particulate silica, kaolin, and calcium carbonate, or organic lubricants, such as long chain fatty acid ester. If necessary, additives such as stabilizers, colorants, antioxidants, antifoams, antistatic agents, and ultraviolet absorbers may be included.

Any of the polyesters can be produced by polymerization by a conventional method. For example, polyester can be obtained using the direct esterification method which reacts dicarboxylic acid and diol directly, the transesterification method which reacts dicarboxylic acid dimethyl ester, and diol, etc. The polymerization can also be carried out by any of batch and continuous methods.

Further, as a structural unit of the polybutylene terephthalate polymer used in the present invention, a polyester copolymer composed of a high melting point crystalline polyester segment (hard segment) and a low melting point polymer segment (soft segment) having a molecular weight of 20,000 or more, wherein The melting point of the high molecular weight polymer formed only by the high melting point crystalline polyester segment is 200 ° C or higher, and the melting point or softening point of the low melting point polymer segment constituent alone is 80 ° C or lower.

The high melting point crystalline polyester segment constituents have a melting point of 200 ° C. or higher when the fiber-forming high molecular weight polymer is formed only by the constituents thereof, for example, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid and 2,6. Aromatic dicarboxylic acid groups such as naphthalenedicarboxylic acid and ethylene glycol, propylene glycol, tetramethylene glycol, pentamethylene glycol, 2.2-dimethyltriethylene glycol, hexaethylene glycol, decamethyl glycol, p-xylene glycol, and cyclo Polyester segment consisting of residues of oxyacids such as polyester segment p- (β-hydroxyepoxy) benzoic acid and p-oxybenzoic acid pivalactone, consisting of residues of aliphatic, aromatic or substituted diols such as hexanedimethanol, 1.2 Aromatic ether dicarboxylic acids such as bis (4.4'-dicarboxymethylphenoxy) ethane and di (4-carboxyphenoxy) ethane There may be mentioned groups wherein the diol residue polyester segment composed of a bis such as (N-p- carbonate epoxy diphenyl) terephthalic the polyamide ester segments comprising the residue and the diol residue of an aromatic amide dicarboxylic acid of the imide and acid as an example. Further examples thereof include copolyester segments using two or more of the above acids or two or more of the above glycols.

In addition, the low-melting polymer segment component having a molecular weight of 20,000 or more refers to exhibiting a substantially amorphous state in the polyester block copolymer, and the melting point or softening point when measured with only the segment component is 80 ° C or less. The molecular weight is 20,000-30,000 normally, Preferably it is 22,000-27,000.

In addition, the ratio of the low melting polymer segment constituent in the polyester block copolymer is preferably 5 to 50% by weight. An especially preferable ratio is 10-30 weight%. Typical low-melting soft polymer segment components include polyethers such as copolymerized glycols of polyethylene oxide and propylene oxide and copolymerized glycols of ethylene oxide with tetrahydrofuran, polyneopentyl acetate, polyneopentyladi Aliphatic polyesters such as pate and neopentyl sebacate, polymers of cyclic esters such as poly-ε-caprolactone, and the like.

Moreover, it is preferable that the polybutylene terephthalate polymer used by this invention is a polyester polymer using the low melting polymer 1,4 cyclohexane dimethanol. The heat-shrinkable polyester film obtained by using the polyester resin composition containing such a polybutylene terephthalate polymer can easily obtain a low-temperature shrinkage rate, and the effect of suppressing shrinkage rate reduction can be increased, thereby obtaining a time-lapse stability after printing.

Any of the copolyester 1,4 cyclohexanedimethanol can be produced by a conventionally known method. For example, a transesterification method in which dialkyl esters such as dicarboxylic acid dimethyl esters and diols are reacted with cyclic esters, etc., if necessary, using a direct ester method for directly reacting dicarboxylic acids and diols with cyclic esters, etc., as needed. The polymer may be polymerized to obtain a copolymer to obtain a polyester elastomer. The polymerization can be carried out in either batch or continuous manner.

In the case of the heat-shrinkable polyester film according to the present invention, the heat shrinkage ratio is calculated by using Equation 1 below from the length value before and after shrinkage by treatment under hot water in hot water.

[Equation 1]

Thermal contraction rate (%) = {(length before contraction-length after contraction) / length before contraction} × 100

The heat shrinkage rate of the heat-shrinkable polyester film according to the present invention is 35 to 60% and preferably 40 to 60% in the main shrinkage direction after 10 seconds treatment in hot water at 75 ° C. and 10 seconds in hot water at 90 ° C. It is 70% or more in the main shrinkage direction, preferably 72 to 95%, and 5% or less in the direction orthogonal to the main shrinkage direction after 10 seconds treatment in hot water at 90 ° C, preferably 2% or less.

If the heat shrinkage in the main shrinkage direction of the heat-shrinkable polyester film according to the present invention is less than 35% after treatment for 10 seconds in hot water at 75 ° C is not preferred because the low temperature shrinkage is insufficient to increase the temperature for shrinkage. On the contrary, when the heat shrinkage rate exceeds 60%, the heat shrinkage rate is left after the heat shrinkage, which is not preferable because the jumping of the label may occur.

In addition, when the heat shrinkage ratio in the main shrinkage direction of the heat-shrinkable polyester film according to the present invention is less than 70% after treatment for 10 seconds in hot water at 90 ℃ because the shrinkage shortage occurs in the inlet portion of the bottle depending on the shape of the bottle On the contrary, when the heat shrinkage rate exceeds 95%, the heat shrinkage rate remains after heat shrinkage, which is not preferable because the jumping of the label may occur.

In addition, it is preferable that the heat-shrinkable polyester film according to the present invention is treated with hot water at 90 ° C. for 10 seconds, and then 5% or less in the direction orthogonal to the main shrinkage direction. If it exceeds 5%, film properties change or it is difficult to achieve high shrinkage in the main shrinkage direction.

In addition, the heat shrinkage rate of the heat-shrinkable polyester film according to the present invention after storing for 45 days at 35 ° C should be at least 40% of the heat shrinkage in the main shrinkage direction after treatment for 10 seconds in 75 ℃ hot water. If the heat shrinkage rate after storage at 35 ° C. for 45 days is less than 40%, a change in shrinkage completeness condition is required, or in some cases, it is undesirable because the resulting film exhibits poor shrinkage.

On the other hand, although the thickness of the heat-shrinkable polyester film which concerns on this invention is not specifically limited, It is preferable that it is 20-150 micrometers, and it is more preferable that it is 30-125 micrometers as a heat shrinkable film for labels.

The following describes in detail the manufacturing method of the heat-shrinkable polyester film according to the present invention, but is not limited to such a manufacturing method.

First, the polyester raw material used in the present invention is dried using a dryer or vacuum dryer such as a hopper dryer or paddle dryer, melted at a temperature of 200 to 300 ° C, and then extruded into a film form. In extrusion, conventional methods, such as a T-die method and a tubular method, are used. Quench quenching after extrusion to obtain an unstretched film. The unstretched film thus obtained is at a temperature of at least Tg ° C. and less than Tg + 15 ° C., preferably at a ratio of 3.0 to 7.0 times in the transverse direction at a temperature of at least Tg ° C. and less than Tg + 10 ° C., preferably of 3.3 to 5.5 times. Stretch in proportions. The stretched film is heat treated at a temperature of 70 to 100 ° C. as necessary to obtain a heat shrinkable polyester film. The stretching method is not only uniaxially stretched in the lateral direction TD using a tent, but also biaxially stretched in the longitudinal direction MD. Such biaxial stretching may be performed by either a sequential biaxial stretching method or a simultaneous biaxial stretching method, and may be further stretched in the vertical direction or the horizontal direction as necessary.

In addition, in order to achieve the object of the present invention, since the transverse direction (that is, the direction perpendicular to the extrusion direction) is practical as the main shrinkage direction, the above description has described an example of a film production method in the case where the main shrinkage direction is the transverse direction. Even in the case where the shrinkage direction is the longitudinal direction (i.e., the extrusion direction), it is possible to manufacture in accordance with the operation of the method except that the stretching direction is rotated 90 degrees around the line perpendicular to the film surface.

Further, in the present invention, it is preferable to stretch the unstretched film obtained from the polyester at a temperature of at least Tg ° C and below Tg + 15 ° C, preferably at a temperature of at least Tg ° C and below Tg + 10 ° C, but at a temperature of less than Tg ° C. In this case, the heat shrinkage, which is a structural requirement of the present invention, is difficult to obtain, and the transparency of the obtained film is deteriorated, which is not preferable. The film obtained when stretched at a temperature of Tg + 15 ° C. or more has insufficient film hardness at high speed and It is because it is not preferable because the thickness distribution of a film deteriorates remarkably.

In addition, the heat-shrinkable polyester film according to the present invention calculates the thickness distribution of the film from the thickness value of the film using the following equation (2).

[Equation 2]

Thickness Distribution (%) = {(Max.-Min.Thickness) / Average Thickness} ⅹ 100

It is preferable that the thickness distribution of the heat-shrinkable polyester film according to the present invention calculated from Equation 2 is 3% or less, and the film having a thickness distribution of 3% or less is colored in, for example, three-color printing performed at the time of evaluation of shrinkage completion. While it is easy to obtain overlap, films over 3% are undesirable in terms of color overlap. In order to uniformize the thickness distribution of the heat-shrinkable polyester film, when the unstretched film is stretched in the transverse direction using a tenter, the heat transfer coefficient is 0.0013 cal / cm 2 sec. ° C (0.0054 J) in the preheating step performed before the stretching process. /Cm2.sec.k) It is preferable to heat until it reaches a predetermined film temperature at low wind speed so that it may become below. In addition, in order to suppress the internal heat generation of the film due to stretching and to reduce film temperature nonuniformity in the width direction of the film, the heat transfer coefficient of the stretching step is preferably 0.0009 cal / cm 2 sec. ° C (0.0037 J / cm 2 sec.k) or more. Preferably, conditions of 0.0011 cal / cm 2 sec. ° C (0.0045 to 0.0071 J / cm 2 sec.k) or more are preferable. The heat transfer coefficient of the preliminary heating step exceeds 0.0013 cal / cm 2 sec. ° C (0.0054 J / cm 2 sec.k) or the heat transfer coefficient in the stretching step is 0.0009 cal / cm 2 sec. ° C (0.0037 J / cm 2. If the thickness is less than K. k), it is not preferable because the thickness distribution is difficult to be uniform, and when the obtained film is subjected to multicolor printing, the multicolor overlaps and the pattern is shifted.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples are only examples of the present invention and the present invention is not limited thereto.

Polyester used in the following Example and the comparative example is as follows. "IV" represents the intrinsic viscosity.

Polyester A: Polyethylene terephthalate (PET), IV = 0.65 dl / g

Polyester B: TPA / EG / CHDM = 100/170/30 (mol%) copolyester, IV = 0.68 dl / g

Polyester C: Polybutylene terephthalate (PBT) polymer, IV = 0.85 dl / g

EXAMPLE

Example 1

100 wt% of the polyester B was melted at 280 ° C to 300 ° C, extruded from a T die, and then quenched and quenched with a cooling roller to obtain an unstretched film. The glass transition point (Tg) of this unstretched film was 69 degreeC.

The unstretched film was preheated to a heat transfer coefficient of 0.0008 cal / cm 2 sec. ° C. (0.0033 J / cm 2 sec.k) until the film temperature reached 85 ° C., and then a heat transfer coefficient of 0.0012 cal / cm 2 sec in a tenter. It heated at 0.degree. C. (0.0050 J / cm.

Example 2

A mixture of 10% by weight of the polyester C and 90% by weight of the polyester B was melted at 280 ° C to 300 ° C, extruded from a T die, and then quenched with a cooling roller to obtain an unstretched film. The glass transition point (Tg) of this unstretched film was 68 degreeC. Otherwise, a thermally shrinkable polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1.

Example 3

A mixture of 15 wt% of the polyester C and 85 wt% of the polyester B was melted at 280 ° C. to 300 ° C., extruded from a T die, and then quenched with a cooling roller to obtain an unstretched film. The glass transition point (Tg) of this unstretched film was 68 degreeC. Otherwise, a thermally shrinkable polyester film having a thickness of 50 µm was obtained in the same manner as in Example 1.

[Comparative Example]

Comparative Example 1

A film was prepared in the same manner as in Example 1 except that 79 wt% of polyester B and 21 wt% of polyester C were used, but a high shrinkage polyester film having a thickness of 50 μm was not obtained due to the lack of heat shrinkage. It was. This is because when the amount of the polybutylene terephthalate (PBT) polymer used is large (greater than 20%), the resin meltability is uneven and film formation is poor.

Comparative Example 2

A mixture of 10% by weight of polyester A, 80% by weight of polyester B and 10% by weight of polyester C was melted at 280 ° C to 300 ° C, extruded from a T die, and then quenched with a cooling roller to obtain an unstretched film. The glass transition point (Tg) of this unstretched film was 70 degreeC.

The film produced by the method described in Example 1 caused bleaching over the entire width at the tenter outlet, resulting in a lack of heat shrinkage and poor thickness distribution, thereby failing to obtain a normal high shrink film. This is because the Tg temperature of the raw PET polymer (polyester A) is low, so that the crystallization rate is rapidly progressed during film forming, so that transparency is lowered and thickness distribution hunting is difficult to obtain a high shrink film.

Comparative Example 3

A mixture of 80% by weight of polyester A, 10% by weight of polyester B and 10% by weight of polyester C was melted at 280 ° C to 300 ° C, extruded from a T die, and then quenched with a cooling roller to obtain an unstretched film. The glass transition point (Tg) of this unstretched film was 72 degreeC.

The unstretched film was preheated to a heat transfer coefficient of 0.0009 cal / cm 2 sec. In degrees Celsius (0.0037 J / cm 2 sec.k) until the film temperature reached 85 ° C., and then a heat transfer coefficient of 0.0009 cal / cm 2 sec in a tenter. It heated at 0.degree. C. (0.0037 J / cm 2 .sec. K) and stretched 4 times in the transverse direction at 80 ° C. to obtain a heat shrinkable polyester film having a thickness of 50 μm.

Comparative Example 4

Except that 100% by weight of polyester A was used to produce a film in the same manner as described in Example 1, but the heat shrinkage rate and thickness distribution were poor to obtain a normal high shrink film. This is because it is difficult to obtain high shrinkage due to uneven flowability during film forming due to excessive use of a resin material having a low viscosity of the PET polymer (polyester A).

Table 1 below shows polyester compositions, film forming conditions and glass transition points for the films obtained in Examples 1-3 and Comparative Examples 1-4.

TABLE 1

Raw material weight% Film forming condition Glass transition point of unoriented film (℃) Polyester A Polyester B Polyester C Preheating Temperature (℃) Stretching temperature (℃) Elongation ratio Example 1 - 95 5 85 80 4.0 69 Example 2 - 90 10 85 80 4.0 68 Example 3 - 85 15 85 80 4.0 68 Comparative Example 1 - 79 21 85 80 4.0 68 Comparative Example 2 10 80 10 85 80 4.0 70 Comparative Example 3 80 10 10 85 80 4.0 72 Comparative Example 4 100 - - 85 80 4.0 72

Polyester A: TPA / EG = 100/100 (mol%) PET polymer

Polyester B: TPA / EG / CHDM = 100/170/30 (mol%) copolymer

Polyester C: Polybutylene terephthalate (PBT) polymer

TPA: terephthalic acid, EG: ethylene glycol, CHDM: 1,4 cyclohexanedimethanol

Experimental Example

1. Heat shrinkage measurement

The heat-shrinkable film immediately after the production of the heat-shrinkable film or after being stored at 25 ° C. for 1 month was cut into squares of 10 cm × 10 cm so as to have two sides parallel to the transverse and longitudinal directions, respectively. The film was heat-shrunk after being treated for 10 seconds under no load in hot water at 75 ° C. ± 0.5 ° C. or 90 ° C. ± 0.5 ° C., and the lengths in the transverse and longitudinal directions of the film were measured, respectively. The heat shrinkage rate (%) was calculated using the following Equation 1 from the measured length value. The direction with large thermal contraction rate was made into the main shrinkage direction.

[Equation 1]

Thermal contraction rate (%) = {(length before contraction-length after contraction) / (length before contraction)} X 100

2. Shrink Completeness  evaluation

After printing 3 degrees with green, red, and white ink on the heat-shrinkable film, 1,3-Dioxolane was attached to the other end in the main shrinkage direction to prepare a cylindrical label to have a width of 152 mm and a length of 130 mm. The label was placed on a 1.5L PET bottle and affixed to a hot air tunnel (model: SS-200L) labeler for 10 seconds to pass through at a zone temperature of 90 ° C. This test was performed with 20 different samples of each film. Shrinkage completeness was judged by visual observation and evaluated as 2 grade according to the following criteria.

[Shrinkage Completion Evaluation Criteria]

Excellent: none of shrinkage, jumping or lack of shrinkage

Poor: Shrink spots, lack of jumping or shrinkage

3. Evaluation of Tightness after Printing

The film was printed 3 degrees with green, red, and white ink containing toluene, methyl ethyl ketone, and ethyl acetate 3: 5: 2, and then both ends were sealed with 1,3-Dioxolane and 152 mm wide and 130 mm long. Cylindrical labels were prepared such that both ends 5 mm in the length direction were left unprinted. The prepared label was stored in a thermo-hygrostat (model TH-G manufactured by Jeiotech Co., Ltd.) maintained at a temperature of 35 ° C. and a humidity of 70% for 45 days, and then placed on a shoulder and torso area of a commercial 1.5L square PET bottle and heated in a hot air tunnel. Labeled. The hot air tunnel was labeled with a line speed of 150 BPM (bottle per minute) in a shrinking tunnel condition of 180 ° C./195° C./210° C. using the SSI-2503 labeler of Shinsung Eng. The number of labeling was performed 100 times. Among them, when the upper end of the label was rolled inward as shown in FIG. 1, the shrinkage failure was defined, and the shrinkage failure rate (%) was evaluated by the change over time after printing.

4. Glass Transition Point (Tg) Measurement

Using a differential scanning calorimeter (model: DSC TA-2910) manufactured by TA Instruments, an endothermic curve was obtained by raising the temperature of 10 mg of the unstretched film from -40 ° C to 150 ° C at a heating rate of 10 ° C / min. The benefit (Tg) was measured. Two tangent lines were drawn before and after the inflection point of the endothermic curve, and the intersection point was defined as the glass transition point (Tg).

5. Thickness distribution measurement

The films were cut into 5 cm longitudinal and 6 m transverse directions, respectively, and the thickness of the samples was measured using a contact thickness meter (model: MAXAN FA SYSTEM). (Measurement Score = 120) The thickness distribution (ie, thickness distribution) was calculated by the following equation (2) for each sample. In addition, the average value (n = 10) of the thickness distribution was measured and evaluated according to the following criteria.

[Equation 2]

Thickness Distribution (%) = {(Maximum Thickness-Minimum Thickness) / Average Thickness} × 100

[Thickness Distribution Evaluation Criteria]

Excellent: less than 3%

Good: 3% or more, less than 8%

Poor: more than 8%

6. Extreme Viscosity Measurement

2 g of the sample was added to 25 ml of orth-chlorophenol solvent and heated at 110 ° C. for 30 minutes, and then the intrinsic viscosity was measured using a 25 ° C. Ostwald viscometer.

The heat-shrinkable polyester films prepared according to Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to performance evaluation and the like according to the experimental example, and the results are shown in Table 2 below. In Table 2, "TD" represents the transverse direction (main contraction direction), "MD" represents the longitudinal direction (main contraction direction and orthogonal direction), and "time-lapse stability" shows the change with time after 45 days after printing. It shows the shrinkage finish failure rate (%).

TABLE 2

Heat Shrinkage (%) Shrinkage completeness Thickness distribution Tightness (% defective) TD MD 75 ℃ 90 ℃ 75 ℃ Example 1 50 74 One Great Great 0 Example 2 53 74 3 Great Great 0 Example 3 40 70 3 Great Great 0 Comparative Example 1 30 52 2 Bad Great 20 Comparative Example 2 25 45 2 Bad Bad 35 Comparative Example 3 15 30 One Bad Bad 40 ↑ Comparative Example 4 10 25 One Bad Bad 40 ↑

Referring to Table 2, it can be seen that the heat shrinkable polyester film of Examples 1 to 3 prepared according to the present invention is excellent in shrinkage completeness and thickness distribution, and the heat shrinkable polyester film according to the present invention has high quality. It has been found that its effectiveness is high and it is particularly suitable for high shrinkage labels. On the other hand, the heat-shrinkable film obtained in Comparative Example 1 was excellent in thickness distribution but inferior in shrinkage completion, and the heat-shrinkable film obtained in Comparative Example 2 was not suitable for practical use because it caused bleaching, Comparative Examples 3 and 4 It can be seen that the heat-shrinkable film obtained in the present invention was poor in shrinkage due to shrinkage and shrinkage was insufficient. have.

Although the present invention has been described in detail with reference to only a few embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the present invention, and such changes and modifications are within the scope of the appended claims.

According to the heat-shrinkable polyester film according to the present invention, it exhibits excellent shrinkage completeness, which rarely occurs due to heat shrinkage, shrinkage stains, deformation and shrinkage deficiency, shows low reduction of low-temperature shrinkage rate, and excellent aging stability after printing. There is.

Thus, the heat shrinkable polyester film according to the invention is suitable for full labeling of bottles, in particular for full labeling of PET bottles and for glass bottles.

Claims (5)

In the heat shrinkable polyester film, Co-polyester composition comprising 80 to 95% by weight of a copolyester polyester composition in which a first component of terephthalic acid and a second component of a diol composed of ethylene glycol and 1,4-cyclohexanedimethanol are copolymerized with a polybutylene terephthalate polymer 5 It contains-20 weight%, The heat-shrinkable polyester film characterized by the above-mentioned. The method of claim 1, The heat shrinkage rate of the heat-shrinkable polyester film is 35 to 60% in the main shrinkage direction after treatment for 10 seconds in hot water at 75 ℃, 70 to 95% in the main shrinkage direction after treatment for 10 seconds in hot water at 90 ℃, After treatment for 10 seconds in hot water at 90 ℃ for 5 seconds or less in the direction orthogonal to the main shrinkage direction, and stored for 45 days at 35 ℃ or less after the heat shrinkage treatment in hot water at 75 ℃ for 10 seconds to the main shrinkage direction A heat shrinkable polyester film, characterized in that 40% or more of the heat shrinkage. The method of claim 2, The heat-shrinkable polyester film is a heat shrinkable polyester film, characterized in that the thickness distribution is 3% or less. The method according to any one of claims 1 to 3, The non-stretched film of the heat-shrinkable polyester film is stretched at a temperature of Tg ℃ or more and less than Tg + 15 ℃, heat shrinkable polyester film. The method according to any one of claims 1 to 3, The unstretched film of the heat-shrinkable polyester film is carried out with a heat transfer coefficient of 0.0013 cal / cm 2 sec. ° C. (0.0054 J / cm 2 sec.k) or less in the preheating step performed before the stretching step. A heat-shrinkable polyester film, characterized in that it is carried out with a heat transfer coefficient of at least 0.0009 cal / cm 2 .sec. ° C. (0.0037 J / cm 2 .sec. K).

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