JP3736616B2 - Heat-shrinkable polyester film - Google Patents

Description

【００７９】
表１における温湯収縮率の変化率は、７０〜８０℃における温湯収縮率の平均変化率（％／℃）を示す。
【００８０】
上記表１から明らかなように、実施例１〜４で得られたフィルムはいずれも収縮仕上り性が良好であった。また、厚み分布も良好であった。従って、本発明の熱収縮性ポリエステル系フィルムは高品質で実用性が高く、特に収縮ラベル用として好適である。
【００８１】
一方、比較例１で得られた熱収縮性フィルムは厚み分布が劣る。また比較例１、３及び４で得られた熱収縮性フィルムは、収縮によってシワ、収縮不足が発生し、いずれも収縮仕上り性が劣る。このように比較例で得られた熱収縮性ポリエステル系フィルムはいずれも品質が劣り、実用性が低いものであった。
【００８２】
【発明の効果】
本発明によれば、ボトルのフルラベル用、特に２リットルサイズなどの大型ペットボトルのフルラベル用に好適な熱収縮性ポリエステル系フィルムが提供される。本発明の熱収縮性ポリエステル系フィルムは、ボトルのフルラベル用として使用する場合、熱収縮によるシワ、収縮斑、歪み及び収縮不足の発生が極めて少ない良好な仕上がり性が可能であり、フルボトルラベル用途として極めて有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-shrinkable polyester film, particularly a heat-shrinkable polyester film suitable for label applications.
[0002]
[Prior art]
As a heat-shrinkable film, particularly a heat-shrinkable film for labeling the body of a bottle, a film made of polyvinyl chloride, polystyrene or the like is mainly used. However, with regard to polyvinyl chloride, in recent years, there has been a problem of generation of chlorine gas when incinerated at the time of disposal, and polystyrene has problems such as difficulty in printing. Furthermore, in collecting and recycling PET bottles, it is necessary to separate labels of resins other than PET such as polyvinyl chloride and polystyrene. For this reason, polyester-based heat-shrinkable films that do not have these problems are attracting attention.
[0003]
In recent years, colored bottles are not suitable for recycling when recycling PET bottles, and alternatives have been studied. Among them, there is a method in which an uncolored bottle is used, and the colored label is thermally contracted over the entire bottle to form a full label.
[0004]
However, when used as a full label of a bottle, the bottle shape is complicated and there are many types, so the conventional heat-shrinkable polyester film may cause a problem in shrinkage finish. In particular, in a full label of a bottle such as a beverage bottle that has a narrow mouth portion and a large difference in bottle diameter from the trunk, heat shrink characteristics such as a high shrinkage ratio are required. Conventional heat-shrinkable polyester films have insufficient shrinkage at the upper neck of the bottle, and a sufficient shrinkage rate cannot be obtained particularly at low temperatures, causing problems such as wrinkles, shrinkage spots, and distortion due to shrinkage. Further, there has been a problem that there is a case where a condition change at the time of shrink finishing is required due to a decrease in low temperature shrinkability during the storage period before the shrinkage, or a shrinkage failure occurs even if the condition is changed.
[0005]
In order to solve these problems, the applicant of the present invention is a film made of a polyester resin composition containing a polyester and a polyester-based elastomer. A heat-shrinkable polyester film having a temperature of 10 to 50% at 85 ° C. for 5 seconds and 75% or more at 85 ° C. for 5 seconds has been developed as a film for full label (Japanese Patent Laid-Open No. 2000-169601). When the film is used for, for example, a full label of a large PET bottle, it was necessary to further increase the shrinkage. However, even if the shrinkage rate at a high temperature is sufficient, there is a problem that it is difficult to sufficiently obtain a low temperature shrinkability. That is, when the shrinkage rate is high, the temperature change of the shrinkage rate is large, and the shrinkage stress becomes too high, so that shrinkage spots, distortion, etc. are likely to occur.
[0006]
Thus, in the case of the full label use of a bottle, the performance was insufficient with the conventional polyester heat-shrinkable film.
[0007]
[Problems to be solved by the invention]
An object of the present invention is a heat-shrinkable polyester film suitable for full labeling of bottles, particularly for full labeling of large-sized PET bottles such as 2 liters, and the occurrence of wrinkles, shrinkage spots, and distortion due to heat shrinkage is extremely small. The object is to provide a heat-shrinkable polyester film.
[0008]
[Means for Solving the Problems]
As a result of intensive studies to solve the various problems of the prior art, the present inventor has found that the above object can be achieved by setting the hot water shrinkage rate of the heat shrinkable polyester film to a specific range. Based on this, the present invention has been completed.
[0009]
That is, the present invention is a film made of a polyester resin, and the hot water shrinkage rate of the film exceeds 50% at a treatment temperature of 70 ° C. and a treatment time of 5 seconds in the main shrinkage direction, and 75% at 80 ° C. and 5 seconds. The heat shrinkable polyester film is characterized in that the average rate of change in hot water shrinkage at 70 to 80 ° C is 1.45% / ° C or less.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the heat shrinkable polyester film of the present invention, the hot water shrinkage rate of the film exceeds 50% at a treatment temperature of 70 ° C. and a treatment time of 5 seconds in the main shrink direction, and is at least 75% at 80 ° C. and 5 seconds. And the said subject is achieved because the average change rate of the hot water shrinkage | contraction rate in 70-80 degreeC is 1.45% / degrees C or less.
[0011]
The heat-shrinkable polyester film of the present invention is substantially composed of a polyester resin, for example, from a polyester resin composition containing a polyester having a dicarboxylic acid component and a diol component as constituent components and a polyester elastomer. Preferably produced.
[0012]
In the polyester resin composition, the blending ratio of the polyester and the polyester-based elastomer is preferably 50 to 97% by weight for the former and 3 to 50% by weight for the latter with respect to the total amount of both. When the blend amount of the polyester elastomer is less than 3% by weight, it is difficult to obtain a sufficient shrinkage rate, particularly at a low temperature, for example, about 70 ° C., and the shrinkage finish tends to be reduced, whereas 50% by weight If it exceeds, wrinkles, shrinkage spots and distortions due to shrinkage tend to occur. The blending ratio of the polyester and the polyester-based elastomer is 70 to 95% by weight, particularly 80 to 93% by weight for the former and 5 to 30% by weight, particularly 7 to 20% by weight for the latter, based on the total amount of both. More preferably.
[0013]
  polyester
Examples of the dicarboxylic acid component constituting the polyester used in the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, and orthophthalic acid, and aliphatics such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid. And alicyclic dicarboxylic acids such as dicarboxylic acid and cyclohexanedicarboxylic acid.
[0014]
When the aliphatic dicarboxylic acid is contained, the content is preferably less than 3 mol%. A heat-shrinkable polyester film obtained using a polyester containing 3 mol% or more of these aliphatic dicarboxylic acids has insufficient film stiffness at high-speed mounting.
[0015]
Further, it is preferable not to contain a trivalent or higher polyvalent carboxylic acid (for example, trimellitic acid, pyromellitic acid and anhydrides thereof). In a heat-shrinkable polyester film obtained using a polyester containing these polyvalent carboxylic acids, it is difficult to achieve a necessary high shrinkage rate.
[0016]
Examples of the diol component constituting the polyester used in the present invention include aliphatic diols such as ethylene glycol, propanediol, butanediol, neopentyl glycol, and hexanediol, and alicyclic groups such as 1,4-cyclohexanedimethanol and dimer diol. Examples thereof include aromatic diols such as diols and bisphenol A ethylene oxide adducts.
[0017]
The polyester used in the present invention contains at least one of diols having 3 to 6 carbon atoms (for example, propanediol, butanediol, neopentylglycol, hexanediol, etc.), and have a glass transition point (Tg). Polyester adjusted to 60 to 75 ° C is preferable.
[0018]
In order to obtain a heat-shrinkable polyester film having particularly excellent shrinkage finishing properties, it is preferable to use neopentyl glycol as one type of diol component. In particular, neopentyl glycol is more preferably used in an amount of 15 mol% or more, more preferably 15 to 25 mol%, based on the total diol component.
[0019]
Further, the diol component does not contain a diol having 8 or more carbon atoms (for example, octanediol) or a trihydric or higher polyhydric alcohol (for example, trimethylolpropane, trimethylolethane, glycerin, diglycerin, etc.). It is preferable. In a heat-shrinkable polyester film obtained using a polyester containing these diols or polyhydric alcohols, it is difficult to achieve a necessary high shrinkage rate.
[0020]
Furthermore, it is preferable that the diol component contains as little diethylene glycol, triethylene glycol, and polyethylene glycol as possible. In particular, diethylene glycol is easily present because it is a by-product component during polyester polymerization. However, in the polyester used in the present invention, it is preferable to adjust the diethylene glycol content to be less than 4 mol%.
[0021]
In addition, the content rate of the acid component in the polyester used by this invention and a diol component is a content rate with respect to the acid component of the whole polyester, and a diol component, when mixing and using 2 or more types of polyester. It does not matter whether transesterification has taken place after mixing.
[0022]
The polyester can be produced by polymerization by a conventionally known method. For example, the polyester can be obtained by using a direct esterification method in which a dicarboxylic acid and a diol are directly reacted or a transesterification method in which a dialkyl ester such as a dicarboxylic acid dimethyl ester is reacted with a diol. The polymerization may be performed by either a batch method or a continuous method.
[0023]
  Polyester elastomer
Next, the polyester elastomer used in the present invention is a copolymer comprising a high-melting crystalline polyester segment (hard segment) and a low-melting-point soft polymer segment (soft segment) having a molecular weight of 400 or more, and a high-melting crystal. Unit having a melting point of 200 ° C. or higher when a high-molecular-weight polymer is formed only from a functional polyester segment component, and a melting point or softening point of 80 ° C. or lower when measured only by a low-melting soft polymer segment component A polyester block copolymer consisting of
[0024]
The high-melting crystalline polyester segment constituent component has a melting point of 200 ° C. or higher when only the constituent component is made into a fiber-forming high molecular weight polymer. For example, terephthalic acid, isophthalic acid, 1,5-naphthalene Aromatic dicarboxylic acid residues such as dicarboxylic acid and 2,6-naphthalenedicarboxylic acid, ethylene glycol, propylene glycol, tetramethylene glycol, pentamethylene glycol, 2,2-dimethyltrimethylene glycol, hexamethylene glycol, decamethylene Polyester segments composed of residues of aliphatic, aromatic or alicyclic diols such as glycol, p-xylene glycol and cyclohexanedimethanol; p- (β-hydroxyethoxy) benzoic acid, p-oxybenzoic acid pivalolactone, etc. Is it an oxyacid residue? A polyester segment comprising: residues of aromatic ether dicarboxylic acids such as 1,2-bis (4,4′-dicarboxymethylphenoxy) ethane, di (4-carboxyphenoxy) ethane, and residues of diols similar to those described above Polyether ester segments comprising: polyamide ester segments comprising aromatic amide dicarboxylic acid residues such as bis (N-paracarboethoxyphenyl) terephthalimide and diol residues similar to those described above.
[0025]
Furthermore, a copolymerized polyester segment using two or more of any of the above acids and / or two or more of any of the above glycols may also be used.
[0026]
Further, the low melting point soft polymer segment constituent component having a molecular weight of 400 or more shows a substantially amorphous state in the polyester block copolymer, and the melting point or softening when measured only with the segment constituent component. A point means 80 degrees C or less. The molecular weight is 400-8000 normally, Preferably it is 700-5000.
[0027]
Moreover, it is preferable that the ratio of the low melting-point soft polymer segment structural component in a polyester-type block copolymer is 1 to 90 weight%. A particularly desirable ratio is 5 to 80% by weight.
[0028]
Typical low melting point soft polymer segment constituents include polyethylene oxide glycol, polypropylene oxide glycol, polytetramethylene oxide glycol, copolymer glycol of ethylene oxide and propylene oxide, copolymer glycol of ethylene oxide and tetrahydrofuran, etc. Examples thereof include aliphatic polyesters such as polyether, polyneopentyl azelate, polyneopentyl adipate, and polyneopentyl sebacate, and polymers of cyclic esters such as poly-ε-caprolactone.
[0029]
The polyester-based elastomer is usually preferably contained in an amount of about 3 to 50% by weight, more preferably 5 to 30% by weight, and more preferably 7 to 20% by weight in the polyester resin composition constituting the polyester-based film. It is particularly preferable to let it lie.
[0030]
The polyester elastomer used in the present invention is particularly preferably a polyester block copolymer using poly-ε-caprolactone as the low melting point soft polymer segment. By using a polyester resin composition containing such a polyester elastomer, the resulting heat-shrinkable polyester film is likely to exhibit low-temperature shrinkage, and has the advantage that the effect of suppressing shrinkage stress is increased.
[0031]
Any of the polyester elastomers can be produced by a conventionally known method. For example, a transesterification method in which a dialkyl ester such as dimethyl ester of dicarboxylic acid and a diol are reacted with a cyclic ester, if necessary, or a direct esterification in which a dicarboxylic acid and a diol are directly reacted with a cyclic ester, if necessary. By using a method or the like, a polyester elastomer is obtained by polymerizing to a predetermined block copolymer. The polymerization may be performed by either a batch method or a continuous method.
[0032]
Other ingredients
In the polyester resin composition, as other components, for example, an inorganic lubricant such as titanium dioxide, fine-particle silica, kaolin, calcium carbonate, or the like, for example, a long chain is used in order to improve the slipperiness of the obtained film film. It is also preferable to contain an organic lubricant such as a fatty acid ester. Moreover, you may contain additives, such as a stabilizer, a coloring agent, antioxidant, an antifoamer, an antistatic agent, and an ultraviolet absorber, as needed.
[0033]
  Heat shrinkable polyester film
In the heat-shrinkable polyester film of the present invention, the hot water shrinkage rate of the film is 50% or more at a treatment temperature of 70 ° C. and a treatment time of 5 seconds in the main shrink direction, and is 75% or more at 80 ° C. and 5 seconds. And the average change rate of hot water shrinkage | contraction rate in 70-80 degreeC needs to be 1.45% / degrees C or less. The shrinkage rate at a treatment temperature of 70 ° C. is a measure of low-temperature shrinkage, and the shrinkage rate at a treatment temperature of 80 ° C. is a measure of final shrinkage.
[0034]
Here, the hot water temperature shrinkage rate of the film is calculated from the length before and after the shrinkage when immersed in warm water without load.
Thermal shrinkage rate (%) = [(length before shrinkage−length after shrinkage) / length before shrinkage] × 100
It is calculated by. Also, the main contraction direction. It means the direction with large heat shrinkage.
[0035]
If the hot water shrinkage in the main shrinkage direction is 50% or less at a treatment temperature of 70 ° C. and a treatment time of 5 seconds, the low-temperature shrinkage is insufficient and the shrinkage temperature needs to be increased. It is not preferable because wrinkles and folds are likely to occur. Thus, by making the hot water shrinkage rate at 70 ° C. exceed 50%, even when the final shrinkage rate is increased, the hot water shrinkage rate can be gradually reduced, and the occurrence of shrinkage spots and the like can be prevented. The hot water shrinkage is preferably 55 to 75%, more preferably 60 to 75%. When the shrinkage rate exceeds 75%, the label may jump up due to heat shrinkage. Here, “the jumping of the label” is a phenomenon in which the upper end portion is turned outward when the container is mounted.
[0036]
If the hot water shrinkage rate in the main shrinkage direction is less than 75% at a treatment temperature of 80 ° C and a treatment time of 5 seconds, the shrinkage will be insufficient and the bottle may float or the mouth may shrink depending on the shape of the bottle. Is not preferable because it becomes insufficient. The hot water shrinkage rate is preferably 75 to 95%. When the shrinkage rate exceeds 95%, the label may jump up because of the force of further shrinkage after heat shrinkage.
[0037]
Moreover, when the average change rate of hot water shrinkage | contraction rate in 70-80 degreeC exceeds 1.45% / degreeC, since shrinkage | contraction speed | velocity becomes large and a wrinkle, a shrinkage spot, etc. become easy to generate | occur | produce, it is unpreferable. The average rate of change is preferably 1.40 to 0.30% / ° C.
[0038]
Although the thickness of the heat-shrinkable polyester film of the present invention is not particularly limited, the heat-shrinkable film for labels is preferably 10 to 200 μm, and more preferably 20 to 100 μm.
[0039]
Next, although a specific example is demonstrated about the manufacturing method of the heat-shrinkable polyester film of this invention, it is not limited to this manufacturing method.
[0040]
The raw material of the polyester or polyester elastomer used in the present invention is dried using a dryer such as a hopper dryer or paddle dryer, or a vacuum dryer, melted at a temperature of 200 to 300 ° C., and extruded into a film form. In extruding, any existing method such as a T-die method or a tubular method may be employed. After extrusion, it is cooled rapidly to obtain an unstretched film.
[0041]
The obtained unstretched film is at a temperature of Tg−5 ° C. or higher and lower than Tg + 10 ° C., preferably at a temperature of Tg−5 ° C. to Tg, 3.0 times or more in the transverse direction, preferably 3.5 to 7. The film is stretched 0 times, more preferably 5.0 to 7.0 times. If the draw ratio is less than 3.0, it is difficult to obtain a sufficient shrinkage.
[0042]
When it extends | stretches at the temperature below Tg-5 degreeC, it becomes difficult to obtain the hot water shrinkage | contraction rate which is a structural requirement of this invention, and it exists in the tendency for the transparency of the film obtained to also fall. In addition, when stretched at a temperature of Tg + 10 ° C. or higher, the resulting film has insufficient film stiffness when mounted at high speed, and the thickness unevenness of the film is significantly impaired, or a sufficient shrinkage rate cannot be obtained. It tends to be.
[0043]
The stretching method is not limited to lateral uniaxial stretching with a tenter, but may be additionally biaxially stretched in the longitudinal direction. Such biaxial stretching may be performed by any of a sequential biaxial stretching method and a simultaneous biaxial stretching method. Further, if necessary, restretching may be performed in the longitudinal direction or the transverse direction.
[0044]
Then, if necessary, heat treatment is performed at a temperature of 60 to 100 ° C. to obtain a heat-shrinkable polyester film.
[0045]
In order to achieve the object of the present invention, the lateral direction is practical as the main shrinking direction. Thus, the example of the film forming method in the case where the main shrinking direction is the lateral direction has been described above. Even when the shrinking direction is the longitudinal direction, a film can be formed according to the operation of the above method except that the stretching direction in the above method is changed by 90 degrees.
[0046]
From the thickness of the film, the heat-shrinkable polyester film of the present invention has the formula
Thickness distribution (%) = [(maximum thickness−minimum thickness) / average thickness] × 100
It is preferable that the thickness distribution of the film calculated in (5) is 6% or less. More preferably, it is 5% or less.
[0047]
If the film has a thickness distribution of 6% or less, for example, it is easy to superimpose colors in three-color printing performed at the time of shrinkage finish evaluation. Is not preferable because it becomes difficult.
[0048]
In order to make the thickness distribution of the heat-shrinkable polyester film uniform, when the film is stretched in the transverse direction using a tenter, the heat transfer coefficient is 0.0013 calories / min in the preheating process performed prior to the stretching process. cm²-Heating is preferably performed at a low wind speed until a predetermined film temperature is reached so as to be equal to or less than sec.
[0049]
In addition, in order to suppress the internal heat generation of the film accompanying stretching and reduce the film temperature unevenness in the width direction, the heat transfer coefficient of the stretching process is 0.0009 cal / cm.²· Sec · ° C or higher, preferably 0.0011 to 0.0013 calories / cm²・ The condition of sec ・ ℃ is good.
[0050]
The heat transfer coefficient of the preheating process is 0.0013 calories / cm²・ If it exceeds sec ・ ℃, the heat transfer coefficient in the stretching process is 0.0009 calories / cm²When the temperature is less than sec · ° C., it is difficult to obtain a uniform thickness distribution, and when the obtained film is subjected to multicolor printing, misalignment of the patterns is likely to occur due to the superposition of multiple colors.
[0051]
The heat-shrinkable polyester film of the present invention can be suitably used as a heat-shrinkable label such as a PET bottle, particularly as a full label. As a method of use in this case, for example, on the side facing the bottle of the film of the present invention, if necessary, after printing the product name, logo mark, description, etc., coloring, the film is rolled into a cylindrical shape, Both ends are solvent-bonded to form a cylindrical heat-shrink label. Next, this heat-shrink label is supplied to an automatic label mounting apparatus, and continuously attached to an object to be attached such as a bottle or a bottle, and is passed through a steam tunnel or the like to be shrunk and the label is attached to the object to be attached. To put on.
[0052]
【Example】
Hereinafter, although an example and a comparative example are given and the present invention is explained still more concretely, the present invention is not limited by these examples.
[0053]
Various characteristics in each example are obtained by the following methods.
[0054]
(1) Hot water shrinkage
The film is cut into a 10 cm × 10 cm square, immersed in warm water at a predetermined temperature ± 0.5 ° C. for a predetermined time and heat-shrinked, and then the vertical and horizontal dimensions of the film are measured. The thermal shrinkage rate was determined according to the following formula.
[0055]
Thermal shrinkage rate (%) = [(length before shrinkage−length after shrinkage) / length before shrinkage] × 100
The direction in which the heat shrinkage rate is large was taken as the main shrinkage direction. The average rate of change (% / ° C.) of the hot water shrinkage at 70 to 80 ° C. is a value obtained by dividing the difference between the hot water shrinkage at 70 ° C. and the hot water shrinkage at 80 ° C. by 10.
[0056]
(2) Shrinkage finish
The heat-shrinkable film was printed in advance with three colors of grass-colored, gold-colored, and white-colored inks from Toyo Ink Manufacturing Co., Ltd.
[0057]
Using a steam tunnel manufactured by Fuji Astec Inc (model “SH-1500-L”), a 2000 ml PET bottle (height 31 cm, center trunk length 33.3 cm) at a passage time of 5 seconds and a zone temperature of 85 ° C. ) Bottles used in Japanese Coca-Cola refreshing beauty tea) (number of measurements = 20).
[0058]
Evaluation was performed visually, and the evaluation criteria were as follows.
[0059]
○: No wrinkles, jumping up, insufficient shrinkage,
X: Wrinkles, jumping up, or insufficient shrinkage occurred.
[0060]
(3) Tg (glass transition point)
Using DSC (model “DSC220”) manufactured by Seiko Denshi Kogyo Co., Ltd., 10 mg of an unstretched film was heated from −40 ° C. to 120 ° C. at a heating rate of 20 ° C./min, and an endothermic curve obtained. I asked more. A tangent line was drawn before and after the inflection point of the endothermic curve, and the intersection was defined as Tg (glass transition point).
[0061]
(4) Thickness distribution
Using a contact thickness meter (model “KG60 / A”) manufactured by Anritsu Co., Ltd., the thickness of the sample of 5 cm in the vertical direction and 50 cm in the horizontal direction was measured (measurement number = 20).
Thickness distribution (%) = [(maximum thickness−minimum thickness) / average thickness] × 100
Thus, the thickness distribution (thickness variation) was calculated. Moreover, based on the average value (n = 50) of the thickness distribution, the thickness distribution was evaluated according to the following criteria.
[0062]
○: thickness distribution of 6% or less,
Δ: thickness distribution greater than 6% and less than 10%,
X: Thickness distribution 10% or more.
[0063]
(5) Intrinsic viscosity
A 200 mg sample was added to 20 ml of a mixed solvent of phenol / tetrachloroethane = 50/50, heated at 110 ° C. for 1 hour, and then measured at 30 ° C.
[0064]
The polyester used in the examples and comparative examples is as follows.
[0065]
Polyester A: Polyethylene terephthalate (Intrinsic viscosity (IV); 0.75 dl / g),
Polyester B: Polyester (IV; 0.72 dl / g) composed of 70 mol% ethylene glycol and 30 mol% neopentyl glycol and terephthalic acid,
Polyester elastomer C: Polyester block copolymer (IV; 1.30 dl / g) comprising 70% by weight of polybutylene terephthalate and 30% by weight of poly-ε-caprolactone,
Polyester D: Polybutylene terephthalate (IV; 1.20 dl / g).
[0066]
Example 1
A polyester resin composition in which 6% by weight of polyester A, 84% by weight of polyester B and 10% by weight of polyester elastomer C were mixed was melted at 280 ° C., extruded from a T-die, and quenched with a chill roll to obtain an unstretched film. The unstretched film had a Tg of 68 ° C.
[0067]
The unstretched film was preheated until the film temperature reached 79 ° C., and then stretched 6 times at 67 ° C. in the transverse direction with a tenter to obtain a heat-shrinkable polyester film having a thickness of 50 μm.
[0068]
Example 2
A polyester resin composition in which 6% by weight of polyester A, 79% by weight of polyester B and 15% by weight of polyester elastomer C were mixed was melted at 280 ° C., extruded from a T-die, and quenched with a chill roll to obtain an unstretched film. The unstretched film had a Tg of 65 ° C.
[0069]
The unstretched film was preheated until the film temperature reached 70 ° C., and then stretched 6 times at 67 ° C. in the transverse direction with a tenter to obtain a heat-shrinkable polyester film having a thickness of 50 μm.
[0070]
Example 3
A heat-shrinkable polyester film having a thickness of 50 μm was obtained in the same manner as described in Example 1 except that the draw ratio was 5.3 times.
[0071]
Example 4
A heat-shrinkable polyester film having a thickness of 50 μm was obtained in the same manner as in Example 2 except that the draw ratio was 5.3 times.
[0072]
Comparative Example 1
A heat-shrinkable polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the stretching temperature was 83 ° C.
[0073]
Comparative Example 2
A film was formed in the same manner as described in Example 1 except that the stretching temperature was 61 ° C. The film was whitened over the entire width at the tenter exit.
[0074]
Comparative Example 3
A polyester resin composition in which 15% by weight of polyester A, 75% by weight of polyester B and 10% by weight of polyester D were mixed was melted at 280 ° C., extruded from a T-die, and quenched with a chill roll to obtain an unstretched film. The unstretched film had a Tg of 69 ° C.
[0075]
The unstretched film was preheated until the film temperature reached 85 ° C., and then stretched 5.0 times at 74 ° C. in the transverse direction with a tenter to obtain a heat-shrinkable polyester film having a thickness of 50 μm.
[0076]
Comparative Example 4
A heat-shrinkable polyester film having a thickness of 50 μm was obtained in the same manner as described in Example 1 except that the draw ratio was changed to 4.0 times.
[0077]
Table 1 shows the evaluation results of the films obtained in Examples 1 to 4 and Comparative Examples 1 to 4.
[0078]
[Table 1]

[0079]
The change rate of the hot water shrinkage rate in Table 1 indicates the average change rate (% / ° C) of the hot water shrinkage rate at 70 to 80 ° C.
[0080]
As apparent from Table 1 above, the films obtained in Examples 1 to 4 all had good shrinkage finish. The thickness distribution was also good. Therefore, the heat-shrinkable polyester film of the present invention has high quality and high practicality, and is particularly suitable for shrinkage labels.
[0081]
On the other hand, the heat-shrinkable film obtained in Comparative Example 1 has a poor thickness distribution. In addition, the heat-shrinkable films obtained in Comparative Examples 1, 3, and 4 are wrinkled and insufficiently shrunk due to shrinkage, and all of them have poor shrinkage finish. Thus, all the heat-shrinkable polyester films obtained in the comparative examples were inferior in quality and low in practicality.
[0082]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the heat-shrinkable polyester-type film suitable for the full label of a bottle, especially for large labels of large sized PET bottles, such as a 2 liter size, is provided. When the heat-shrinkable polyester film of the present invention is used for full labeling of bottles, it can achieve good finish with very little wrinkles, shrinkage spots, distortion and insufficient shrinkage due to heat shrinkage, and as a full bottle label application. Very useful.

Claims (5)

A full-label film for a bottle comprising a polyester resin composition containing polyester and a polyester-based elastomer , wherein the hot water shrinkage of the film exceeds 50% in the main shrinkage direction at a treatment temperature of 70 ° C. and a treatment time of 5 seconds. A heat-shrinkable polyester film, which is 75% or more at 80 ° C. for 5 seconds and an average rate of change in hot water shrinkage at 70 to 80 ° C. is 1.45% / ° C. or less. The heat-shrinkable polyester film according to claim 1 , wherein the polyester elastomer is a polyester block copolymer using poly-ε-caprolactone as a low melting point soft polymer segment. The heat according to claim 1 or 2 , wherein the polyester resin composition contains 50 to 97% by weight of the former and 3 to 50% by weight of the latter with respect to the total amount of the polyester and the polyester-based elastomer. Shrinkable polyester film. The heat-shrinkable polyester film according to any one of claims 1 to 3 , wherein the thickness distribution is 6% or less. The label produced using the heat-shrinkable polyester-type film in any one of Claims 1-4 .