TWI270560B - Heat-shrinkable multilayered polyester film for packaging - Google Patents

Abstract

A heat-shrinkable multilayered film for packaging comprises at least three layers and is produced by a coextrusion method, in which the surface layers each comprises as the main component a mixture of a polyester (A) obtained from an acid ingredient comprising more than 80 mole% of terephthalic acid (TA) and either naphthalenedicarboxylic acid (NDC) or isophthalic acid (IA) and a glycol ingredient consisting more than 80 mole% of ethylene glycol (EG) and a polyester (B) obtained from an acid ingredient comprising TA and IA and a glycol ingredient consisting mainly of tetramethylene glycol, and at least one of the core layer(s) comprises as the main component a polyester (C) obtained from an acid ingredient comprising TA and IA and a glycol ingredient consisting mainly of EG. The multilayered film has a shrinkage of 35% or higher in the main shrinkage direction and a shrinkage of 5% or lower in the direction perpendicular thereto. The polyester A is formed of terephthalic acid (TA) and either naphthalenedicarboxylic acid (NDC) or isophthalic acid (IA) in a mole ratio of 95/5 to 80/20. The main diol is ethylene glycol, and the polyester B contains terephthalic acid and isophthalic acid in a mole ratio of 90/10 to 60/40. The main component of diol is tetramethylene glycol, and the polyester C is formed of an acid component consisting of terephthalic acid (TA) and isophthalic acid (IA) in a mole ratio of 95/5 to 80/20. The main ingredient of ethylene glycol is glycol. The invented film can be used as a packaging material due to its excellent properties in endurance, dimensional stability, mechanical strength, oil resistance, solvent resistance, and printability.

Description

1270560 (1) Description of the Invention [Technical Field of the Invention] The present invention relates to a heat-shrinkable multilayer polyester film for use in packaging articles. More specifically, it is a multilayer polyester film which is excellent in durability, dimensional stability, mechanical strength, and solvent resistance, and is useful as a shrink wrap material having excellent printability.

[Prior Art] In the shrink wrap application including the label of the bottle, a polyester shrink film, a non-polyester type shrink film such as polystyrene or polyvinyl chloride is used. Among them, the polyester film-based shrink film is superior to non-polyester-based shrink film in terms of solvent resistance, durability, dimensional stability, and mechanical strength. However, although the polyester-based shrink film is excellent in the shrinkability and the adhesion to the solvent by the use of the non-crystalline raw material, it is required to be improved because the mechanical strength is insufficient.

In order to improve the mechanical strength of the polyester-based shrink film, a method of using a three-layer structure and using a polyester having high crystallinity in the core layer has been proposed in Japanese Patent Laid-Open Publication No. Hei 08- 3 3 3 8 5 3 . In this proposal, in order to obtain the solvent adhesion of the surface layer polymer, the ratio of the polyethylene terephthalate component is set to 80% or less, due to the crystallinity of the surface and the core layer. The difference in interlayer peeling caused by the difference is not sufficient for the purpose of improving the properties of the polyester-based shrink film. The tendency of such interlayer peeling is also significant when the core layer and the polymer layer of the surface layer are different. -6 - (2) (2) 1270560 OBJECTS OF THE INVENTION The present inventors have focused on solving the disadvantages of the above-mentioned polyester-based shrink film, and found that the polyester and the core layer used for the surface layer are used. The polyester is as close as possible to the copolymer of the ethylene terephthalate component or a mixture thereof, thereby improving the affinity between the surface layer and the core layer and obtaining a heat shrinkable polymer having good mechanical strength and adhesion. The fact of the ester film 'finished the invention. The heat-shrinkable multi-layer polyester film for packaging of the present invention is a surface layer of at least three layers of a multilayer film produced by co-extrusion film formation (polyester)

The layer 1) and the other surface layer (polyester layer 2) are composed of a mixture of polyester A and polyester B as a main component, and the terephthalic acid component of the mixture is 80 of the total acid component. More than 5% by mole, the ethylene glycol component is 80% by mole or more of the total diol component, and at least the ruthenium layer of the core layer is a multilayer film of a layer (polyester layer 3) mainly composed of polyester c, and It is characterized in that the multilayer film is at 80. (: The shrinkage ratio in the main shrinkage direction when treated in warm water for 1 sec. is 35% or more, and the shrinkage ratio in the direction perpendicular to the main shrinkage direction is 5% or less. Here, the polyester A is in the acid component. The molar ratio of "terephthalic acid" to "naphthalene diacid or isophthalic acid" is composed of 9 5 /5 to 8 0 /2 0, and "ethylene glycol" is the main a polyester having an alcohol component. Further, the polyester B-based acid component has a molar ratio of "terephthalic acid" to "isophthalic acid" of 9 5 / 5 to 60 / 40. And the polyester with "tetramethyl diol" as the main diol component, and the molar ratio of "p-benzoic acid" and "isophthalic acid" in the polyester c-based acid component is % or even " /2〇-7 - (3) 1270560 is composed of a ratio of "ethylene glycol" as the main diol component [for the best form of the invention] [polyester] the surface layer of the multilayered polyester film of the present invention (Polyester layers 1 and i are composed of a molar ratio of "terephthalic acid" to "naphthalenedicarboxylic acid or acid" of an acid component of 95 /5 to 80 +/- 0, and an alcohol component. That is to say " The molar ratio of the polyester-based polyester A to the acid component dicarboxylic acid and the "isophthalic acid" is 90/1 (the ratio of "tetraethylene glycol" The molten mixture of the glycol ester B is used as a main component, and the acid in the mixture is 80% by mole or more of the total acid component, and 80% by mole or more of the ethylene glycol component is polyester. In one aspect, it is a polyester containing terephthalic acid and naphthalene dicarboxylic acid as a diol component in the above ratio, and can be produced by a known method, that is, from p-xylene and 2·6. - a transesterification reaction of dimethyl naphthalene dicarboxylate with ethylene glycol and a direct oligomer of p-phthalic acid and 2,6 naphthalene dicarboxylic acid and ethylene glycol, followed by melt polymerization However, it is also possible to copolymerize with other components within the range of the effect of the film. The acid component of such other copolymerization component may, for example, be adipic acid, sebacic acid or decane dicarboxylic acid. Group of dicarboxylethane dicarboxylic acid, diphenyl dicarboxylic acid 'diphenyl ether dicarboxylic acid polyester. β ester layer 2) isophthalic acid as two Benzene>to 80/40 component of polyparaxylene is a total diol containing an acid component containing dimethyl oxalate' or by esterification to produce the present invention: adipic acid; diphenyl, fluorene dicarboxylate (4) (4) 1270560 An aromatic dicarboxylic acid such as an acid, etc. Further, the diol component may, for example, be diethylene glycol, propylene glycol, neopentyl glycol, butanediol, pentanediol or the like. An aliphatic diol such as a diol; a polyalkylene glycol such as polyethylene glycol, polypropylene glycol or polytetramethylene glycol. These may be used singly or in combination of two or more. Here, in the polyester The amount of the naphthalene dicarboxylic acid component is 5 to 20% by mole in the total acid component, preferably 7 to 18% by mole, more preferably 9 to 15% by mole. When the amount of the naphthalene dicarboxylic acid is 5 mol% or less, the crystallinity at the time of forming the film is too high, so that the sealing property by the solvent required for shrink packaging is insufficient. On the other hand, when it exceeds 20% by mole, the melting point is lowered and the amorphous property is progressed, so that drying and handling at the time of film formation are difficult and practical. Further, another state of the polyester A is a polyester containing ethylene di-carboxylic acid and isophthalic acid as an acid component and ethylene glycol as a diol component, and can be produced by a known method. That is, the transesterification reaction of dimethyl p-dicarboxylate and dimethyl isophthalate with ethylene glycol, or direct esterification with terephthalic acid and isophthalic acid and ethylene glycol. After the oligomer is obtained by melt polymerization, it may be copolymerized with other components within a range that does not impair the effects of the present invention. The acid component of such other copolymerization component may, for example, be an aliphatic dicarboxylic acid such as adipic acid, sebacic acid, sebacic acid or decane dicarboxylic acid; 2,6-naphthalenedicarboxylic acid, Aromatic aromatics such as 2,7-cai dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, and stilbene dicarboxylic acid Dicarboxylic acid, etc. Further, the diol component may, for example, be a diethylene glycol, a propylene glycol 'neopentyl glycol, a butanediol, a pentanediol, a hexanediol or the like (5) 1270560 an aliphatic diol; a polyalkylene glycol such as a diol, a polypropylene glycol or a polytetramethylene glycol. These may be used singly or in combination of two or more.

Here, the amount of the isophthalic acid component in the polyester A is from 5 to 20 mol%, preferably from 7 to 19 mol, more preferably from 1 to 莫8 mol%, in the total acid component. When the amount of the isophthalic acid is 5 mol% or less, the crystallinity at the time of forming the film is too high, so that the sealing property by the solvent required for shrink packaging is insufficient. On the other hand, when it exceeds 20% by mole, the melting point is lowered and the amorphous property is progressed, so that the operation at the time of drying and film formation is difficult and practical.

The amount of the ethylene glycol component in the polyester A is such that the ratio of the ethylene glycol component in the total diol component in the mixture with the polyester b is 8 〇 mol% or more. Therefore, the amount of the B-component of the vinegar A is determined depending on the mixing ratio of the vinegar A and the polyester B, but it is preferably 8 〇 mol% or more, more preferably 90 摩尔% or more.牿佳 is essentially 1 〇〇 耳 %. Substantially 100% of the ear' is meant to include the proportion of the diol component (e.g., diethylene glycol) other than ethylene glycol which is a minor by-product during the polymerization. The polyester B of the present invention is mainly composed of terephthalic acid and isophthalic acid as an acid component, and tetramethyl diol as a diol component, and can be produced by a known method, that is, Transesterification of dimethyl terephthalate and dimethyl isophthalate with tetra-methylene glycol, or by direct esterification of the present monocarboxylic acid and isophthalic acid with tetra-methylene glycol After the granules are obtained, they are obtained by melt polymerization. In the vinegar B, hydrazine; if it does not affect the effects of the present invention, it may be copolymerized with other components. The acid component of such other copolymerization component may, for example, be an aliphatic dicarboxylic acid such as adipic acid, -1 〇-(6) (6) 1270560 azelaic acid, sebacic acid or phenolic dicarboxylic acid. ;phthalic acid; 2,6-naphthalene dicarboxylic acid, 2,7-naphthalenedicarboxylic acid, hydrazine, 5-naphthalenedicarboxylic acid, diphenoxyethyl hydrazine-residual acid, monophenyl bis-acid An aromatic-residual acid such as diphenyl ether dicarboxylic acid or quinone di-residual acid. Further, the diol component may, for example, be an aliphatic diterpene alcohol such as diethylene glycol, propylene glycol, neopentyl glycol, butanediol, pentanediol or 3 glycol; polyethylene glycol or polypropylene glycol; a polyalkylene glycol such as polytetramethylene glycol. These may be used singly or in combination of two or more. The amount of the isophthalic acid in the acid component of the polyacetate B is from 1 to 4 mol%, preferably from 12 to 37 mol%, more preferably from 15 to 33 mol%. For example, the amount of isophthalic acid is 1 〇 mol. /. In the following case, the crystallinity of the surface is raised, so that the sealing property required for the solvent for shrink packaging is insufficient. On the other hand, when it exceeds 40% by mole, the melting point is lowered and the amorphous property is progressed, so that the operation at the time of drying and film formation is difficult and practical. The amount of the tetramethylene glycol component in the polyester B is such that the ratio of the ethylene glycol component in the total diol component in the mixture of the polyesters is 80% by mole or more. Therefore, the amount of the tetramethylene glycol component in the diol component of the polyester B is determined depending on the mixing ratio of the polyester A and the polyester B, and is preferably 80 mol% or more, more preferably More than 90% of the moles, and particularly preferably 100% by mole. By substantially 100% by mole, is meant to include the proportion of diol components other than tetra-methylene glycol which is extremely minor by-product during the polymerization. The present invention is in the multilayer film as at least a layer One layer of polyacetate containing polycene c as the main component, the polyacetate c' is used as the acid- 11 - (7) 1270560 and terephthalic acid and isophthalic acid as the main components. As a diol component and a main component of ethyl alcohol, a known method can be used, that is, a transesterification reaction of p-benzoic acid and isomethyl methacrylate with ethylene glycol, or After the terephthalic acid is directly esterified with terephthalic acid and ethylene glycol to obtain an oligomer, the polymer is obtained by melting the polymer. However, the polyester c may be copolymerized with other components insofar as it does not impair the effects of the present invention. The acid component of such other copolymerization component may, for example, be an aliphatic dicarboxylic acid such as adipic acid, sebacic acid, sebacic acid or decane dicarboxylic acid; phthalic acid; 2,6 -Caidicarboxylic acid, 2,7-naphthalene dicarboxylic acid, hydrazine, 5 naphthalene dicarboxylic acid, one oxyethylene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, bismuth An aromatic dicarboxylic acid such as a carboxylic acid. Further, the diol component may, for example, be an aliphatic diol such as monoethylene glycol, propylene glycol, neopentyl glycol 'butanediol, pentanediol or hexanol; polyethylene glycol or polypropylene glycol; a polyalkylene glycol such as polytetramethylene glycol. These may be used singly or in combination of two or more. The amount of isophthalic acid in the polyester C is 5 to 2 moles. /. Preferably, it is from 7 to 17%, more preferably from 10 to 15%. If the amount of isophthalic acid exceeds 2 〇 %, it is not suitable because of the decrease in the amorphous strength of the core layer. Further, when the amount is 5 mol% or less, crystallization tends to occur and the tear strength is lowered. The amount of the ethylene glycol component in the polyacetic acid C is preferably 80 mol or more, more preferably 90 mol% or more, and particularly preferably substantially 丨〇 mol%. Substantially 100% by mole means the proportion of the diol component (e.g., diethylene glycol) other than ethylene glycol which is produced by a minor amount during the polymerization. -12 - (8) 1270560 The polyester constituting the polyester layer 1 and the polyester layer 2 of the present invention is a mixture (blend) of the polyester A and the polyester B, and the blending ratio thereof is in each mixture. Among the total acid components, the ratio of the terephthalic acid component can be 80 moles. /〇 Above, the proportion of the ethylene glycol component in the total diol component can be 80 moles. Determined by way. When the ratio of the ethylene terephthalate component is 8 Torr or less, the affinity with the polyester C constituting the core layer is deteriorated, so that interlayer peeling may occur after the solvent is bonded. The mixing ratio of the polyester A to the polyester B varies depending on the ratio of the components of the polyester A and the polyester B, but preferably, for example, the weight ratio of the polyester A/polyester B is from 70 to 30 to 95. The range of /5 is particularly good in the range of 80 / 20 to 90 /10. Here, if the polyester component ratio of the polyester layer 1 and the polyester layer 2 is in the above range, the polyester of the same composition may be used, or it may be different, but the high-efficiency production of the multilayer polyester film is ' It is preferred to use the same composition of the vinegar. [Multilayer Polyester Film] The multilayer polyester film of the present invention preferably has a heat Δ of crystal melting

There is Lu, Huaihuai in the process of crystallization and cold crystallization. Force n this △ ττ

When it is 3 (Η / g or less, the mechanical strength of the film is too high, and the degree of crystallization is too high, and the physical property which may be lacking is lowered. In 2, the polyester layer 1 and/or the polyester layer of the present invention is preferably a composition. >13- (9) 1270560 The eyebrow tablet containing an average particle diameter of 2.5 μηι or less. The stalking agent may be inorganic or organic, but preferably inorganic. The agent may be exemplified by cerium oxide, aluminum oxide 'cerium oxide, (iv) calcium 'barium sulfate, and the like, and the organic lubricating agent may be exemplified by + r/7 m ^ ^ ^ , - -" The ketone is in the temple. The average particle size is below 2. 5 μ】Ώ. If the average particle size exceeds 2·5 μ】, it will affect the transparency of the multilayer polyester film as a packaging material. It is not appropriate.

The above slip agent may also be formulated in the polyester layer 3. In the case of the turbidity (h aze, ambiguity) of the multilayered polyester film of the present invention, when it is required to have transparency as a packaging material, it is preferably 15% or less under the thickness of 4 Å, and particularly preferably 〇 %the following. The amount of the above-mentioned slip agent is changed depending on the particle size, but it can be selected within a range that does not affect the film take-up property and transparency.

For the surface layer polymer of the polyester layer 1 and the polyester layer 2 of the present invention, it is possible to use a polyester layer 3 (core layer) by mixing the above-mentioned polyester A, polyester B particles by, for example, an automatic blender. Polyester c is used for the polymer. The polyester A, the polyester B, and the polyester C' are dried separately, melted in an extruder, and discharged from a die to form a multi-layer film, which is stretched and heat-set to form a multi-layered polymer. Ester film. The heat setting temperature of the film is preferably selected in the vicinity of the Tg of a higher temperature among the Tg (glass transition temperature) of the polyester constituting the polyester layer 1 and the polyester layer 2. If the heat setting temperature is too high, the heat shrinkage rate of the product film becomes small, so that the original function for heat shrink packaging is lost. The multilayer polyester film of the present invention needs to be treated in warm water at 80 ° C. ◦ -14 ^ (10) (10) 1270560 The shrinkage ratio in the main shrinkage direction of the soup in the second shrinkage is above 35%, and the shrinkage rate in the direction perpendicular to the main shrinkage direction is less than 5%. If the shrinkage ratio is within this range, the characteristics when used as a heat shrinkable package will be improved. Here, the shrinkage rate is based on ns-Z 1 7 0 9 to measure the plane direction of the film. Further, among the longitudinal directions of the film and the wide direction perpendicularly intersecting the film, the direction in which the shrinkage ratio is the largest is taken as the main shrinkage direction. The shrinkage ratio of the main shrinkage direction in warm water of 80 ° C is preferably 35 to 55 %. Further, the shrinkage ratio in the main shrinkage direction in warm water of 70 ° C is preferably from 5 to 30%. In the case of shrinkage of the multi-layered polyester film, the heat shrinkage of the shrinkage ratio occurs in either the length direction or the wide direction, but actually, it is a right angle in the main shrinkage direction (longitudinal direction or wide direction). There will also be some heat shrinkage in the direction. This heat shrinkage in the direction which becomes a right angle to the main contraction direction needs to be 5 °/. the following. In order to have such uniaxial shrinkage, the uniaxial stretching in the main shrinkage direction is most suitable, but since the uniaxially stretched film is deteriorated in the orientation property of the polymer, the tear resistance is lowered. The time-use use also tends to be slightly stretched in the direction perpendicular to the main contraction direction. In this case, the stretching in the direction perpendicular to the main contraction direction is preferably twice as high as the top, and may be appropriately selected in the range of 1. 〇 to 2 · 〇 depending on the use or desired characteristics. The thickness of the multilayered polyester film of the present invention is preferably from 2 Å to 7 Å μηι, more preferably from J 〇 to 6 〇 μηι, particularly preferably from 3 5 to 5 5 μ m. If the thickness is too thin (for example, 20 μm or less), the deformation resistance (rigidity) of the film becomes weak, and it may be bent or defective when the label is attached. On the contrary, if the thickness is too thick (for example, 7 〇 μ m or more), the deformation resistance of the film is too strong, and -15-(11) 1270560 is difficult to handle during processing. The layer constitution of the multilayered polyester film of the present invention is preferably composed of three layers laminated in the order of the polyester polyester layer 3 / polyester layer 2. In the case of this formation, the solvent resistance of the sacrificial layer is due to the layer which can be sealed with a solvent. Such a laminated structure can be formed by a co-extrusion method using two machines and a multi-tube type die (m u 11 i - m a n i f ο 1 d d i e ) or a feed block, so that it is suitable from the viewpoint of productivity. [Evaluation method] (1) The thickness of the film and the layer structure are made using a dot-type film thickness gauge (dotting type film thi cl. meter). The film is formed in a vertical width of 50 mm in a continuous film-forming direction. The thickness of the continuous film forming direction near the center is measured at 50 points, and the average number of turns is taken as the thickness. However, the measured thickness of the film in the width direction and the length direction is uniform, and it is premised on the thickness of +20 to -20% of the average thickness. In the layer constitution, the film was embedded in an epoxy resin, and after forming a sheet using a glass knife, the cross section was observed under a polarizing microscope to obtain. (2) Heat of crystal melting (ΔHm) 20 mg of the sheet sample was sealed in a pan made of aluminum, and a differential scanning calorimeter (SEIK〇SSC / 5 2 0 0) was used for reading. The sample was heated to a temperature of ° C at a temperature increase rate of 20 ° C /min to determine the crystal melting heat amount. The layer 1/structure can be modified to squeeze the feed [the direction of any film in the direction of ness is not taken to make DSC? 2 80 count into -16 (12) (12) 1270560 spoon 5 times, and the average enthalpy is used as crystal melting Determination of calories 値. (3) Amount of polyethylene terephthalate component (amount of PET unit) Calculating the ratio of the polymer for the surface layer, the molecular weight, and the individual copolymerization ratio 'calculation of each acid component in the surface layer polymer, each diol component Moll number. Among the calculated acid components and diol components, the molar number of the combination of the terephthalic acid (butyl A) component and the ethylene glycol (EG) component is defined as the amount of the polyethylene terephthalate component. Calculation. Namely, it was confirmed that the terephthalic acid component was 80 moles in the total acid component. /. The above, and the case where the ethylene glycol component is 80% by mole or more in the total diol component. (4) Solvent sealing property Two sheets of a film sheet of 1 0 c m X 2 0 c m were prepared as a sample. On the surface of the film sheet prepared on the I sheet, the dioxolane ring was applied in such a manner that the cotton wadding bar impregnated with 1-3 dioxapentane was scanned. The sheet after the quasi-dioxapentane ring was immediately bonded to the other film and pressed using a roller. After pressing, the degree of adhesion of the two film sheets was evaluated according to the following criteria. 〇: Two film sheets are firmly bonded (solvent sealability is good) △ △ : The two film sheets are not sufficiently adhered and peeled off over time (the solvent seal is slightly better). X : Two film sheets were not bonded at all (poor solvent seal). (5) Heat shrinkage rate ► 17 - (13) 1270560 The JIS-Z 1 7 09 is used to measure the main shrinkage direction when treated in 80 °C warm water for 10 seconds and 70 °C warm water for 10 seconds. The heat shrinkage rate in the warm boiling direction in the direction perpendicular to the main contraction direction. The average enthalpy of each measurement point (N) == 3 was taken as the measurement enthalpy. Here, in the film plane direction, the continuous film forming direction of the film (abbreviated as the longitudinal direction) and the shrinkage ratio in the width direction (abbreviated as the lateral direction) perpendicularly intersecting each other are measured, and the direction in which the shrinkage is maximum is taken as the main shrinking direction. (6) Mechanical strength As an evaluation index of the strength of the film, the measurement of the modulus of elasticity is carried out in accordance with n s - K 7 1 2 7. The average enthalpy of the number of measurement points (N) = 5 was measured as 値 〇: in the continuous film formation direction, it was 200 Å or more, and the direction perpendicular to the continuous direction was 4 5 OMP a or more. X: Other than the above. 7) Surface peelability When the layer composition is observed, it is carried out simultaneously. Namely, the film was embedded in a ring of % ^ _ grease, cut into thin pieces using a glass blade, and the cross section was observed under a polarizing microscope, and the surface peeling property was evaluated according to the following criteria. 〇: Peeling was not confirmed (good surface peeling property) X: The peeling of the surface layer was severe due to the impact at the time of sectioning. Δ : Can be peeled off by surface layer (the surface peeling property is slightly good -18 - (14) 1270560 [Embodiment] · [Example 1 to Π and Comparative Examples 1 to 1 4] Modification of polyester A: Dimethylterephthalic acid, 2,6-dimethylnaphthalene dicarboxylic acid, dimethyl isophthalic acid, ethylene glycol as raw materials, tetrabutyl titanate as transesterification catalyst, cerium oxide As a polymerization catalyst or phosphorous acid, it is used as a stabilizer, and a copolymerized polyethylene terephthalate is produced by a usual method. The composition of each component is shown in Table 1. Polyglycol B g system: two Methyl terephthalic acid, dimethyl phthalic acid, and tetramethyl ketone are used as raw materials, and tetrabutyl vinegar titanate is used as a vinegar exchange catalyst, cerium oxide is used as a polymerization catalyst, and phosphorous acid is used as a stabilizer. The copolymerized polybutylene terephthalate was prepared according to the usual method, and the composition of each component is shown in Table 1. Modification of polyester C: dimethyl terephthalic acid, dimethyliso-p-phenylene Xi, Yiyi I as raw material, also used tetrabutyl titanate as vinegar exchange catalyst, cerium oxide as polymerization catalyst, phosphorous As a stabilizer, a copolymerized polyethylene terephthalate is produced by a hanging method, and the composition of each component is as shown in 袠 1. Here, the symbol of the composition component shown in Table 1 is TA. For benzene-formic acid, NDC is 2, naphthalene dicarboxylic acid, IA is isophthalic acid, EG is ethylene glycol, TMG is tetramethylene glycol, and cH is cyclohexane dimethanol. The polyester A and the polyester B were blended to form a polymer for the surface layer, and the polyester C was used as a polymer for the core layer. Polymerization for the surface layer -19- (15) 1270560

The material and the fish and the layer are dried with polyester C at a temperature of 150 ° C for 6 hours, and then supplied to the surface layer with two extruders for the core layer, at a melting temperature of 2 8 〇 to 3 〇〇 C. Melt, use a multi-tube die to meet the surface temperature of 2 〇. (: The cooling drum was quenched to obtain a multilayer unstretched film having a thickness of 180 μm. The multilayer unstretched film thus obtained was subjected to the conditions shown in Table 2 to be perpendicular to the direction of the continuous system. Stretching in the transverse direction and heat-fixing. Thus, a three-layered polyester film composed of two skin layers each having a thickness of 4 μm and a core layer of 42 μηι is obtained. As shown in Table 2, it is understood from the results shown in Table 2 that the films of Examples 1 to 11 are all useful as heat shrinkable packaging materials. On the other hand, Comparative Examples 1, 3, 4, and 1 are The film of 1 1 is poor in adhesion of the surface layer due to the incorporation of a material having high crystallinity. Moreover, the affinity between the surface layer of the film of Comparative Examples 2, 7, and 9 and the core layer is inferior. On the other hand, the films of Comparative Examples 8 and 14 were inferior in strength due to an increase in the amorphousness of the core layer. Further, Comparative Examples 5 and 6,

The film of 1, 2, and 3 is too high in the amorphous state of the surface layer material, and agglomerates upon drying after the stretching treatment, so that film formation is difficult and cannot be evaluated. -20- 1270560 6 Table Light Bale () U00 Φ1 %WM w 33⁄4 I3d s 18 s 900

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(ooi)oLJJ

(οε^αΗΟ/ooaLJJ 00§ # aoaN/(s)vl (a)</(s)vl ao</(s)vl §vl/(ooovl oOVI/oevl oovl/(06)vl ooovl (soaN/ A8)vl (εοαΝ/α6<1 (εδαΝ/asvl (SQaN/aoo)vl (sooNAooovl (ocmvi. (soaN/a8)vl

(a) v§8) <K (Gvl/asvl ao</§vl (a)</§ Vi (inch C\J) VI/(9DV1 ai)vl/(s)vl

-21 - (17)1270560 Table 2

\ Stretching condition Heat setting temperature (°C) Heat shrinkage rate (%) △ Hm 0/g) Surface peeling solvent sealability I Mechanical strength test Stretch ratio Stretching temperature (°C) 7 0°C 8 0° C Aspect and cross-section Example 1 3.7 76 1Ί 3 10 2 50 40 〇〇〇2 3 10 2 50 45 〇〇〇3 3 10 2 50 40 〇〇〇4 3 10 2 50 39 〇〇〇5 3 10 2 50 42 〇〇〇6 3 10 2 50 40 〇〇〇7 3 10 2 50 38 〇〇〇8 3 10 2 50 43 〇〇〇9 3 10 2 50 38 〇〇〇10 3 10 2 50 37 〇〇〇11 3 10 2 50 49 〇〇〇Comparative example 1 3.7 76 11 3 10 2 50 58 〇X 〇2 3 10 2 50 38 △ 〇〇3 3 10 2 50 43 〇△ 〇4 3 10 2 50 37 〇△ 〇5 6 I failed to evaluate due to film making difficulties. 7 ΊΊ 3 10 2 50 33 X 〇〇8 71 72 3 18 4 52 5 〇〇X 9 76 77 3 10 2 50 36 △ 〇〇10 3 10 2 50 41 〇△ 〇11 3 10 2 50 36 〇△ 〇12 13 — Failure to evaluate due to film formation difficulties 14 71 72 3 18 4 52 4 〇〇X -22 - (18) 1270560 Industrial Applicability The present invention The multilayer polyester film, is due to have excellent durability, dimensional stability, mechanical strength, solvent resistance, Qieyi have excellent printability, therefore, be useful as a shrink packaging material by. -twenty three-

Claims (1)

1270560 (Pickup, Patent Application No. 1 ~ ~ Multi-layer polyester film for heat shrink packaging, at least 3 layers of multi-layer film continuously formed by co-extrusion H film forming method, surface layer on either side The melt mixture of polyester ruthenium and polyester ruthenium is mainly composed, and the terephthalic acid component in the mixture constituting the layer is 8 〇 mol% or more of the total acid component, and the ethylene glycol component is the total diol component. In the case of 8 〇 mol% or more, at least 1 layer of the core layer is a multilayer film of a layer mainly composed of polyester C, and the main shrinkage direction of the multilayer film treated in 80 ° C of warm water for 10 seconds The shrinkage ratio is 35 % or more, and the shrinkage ratio in the direction perpendicular to the main shrinkage direction is 5 ° / 〇 or less, but "terephthalic acid" and "naphthalenedicarboxylic acid or The molar ratio of isophthalic acid is 95 /5 to 80 +/- 0. The main diol component is "ethylene glycol", and the polyester B is the acid component of "terephthalic acid". The molar ratio of r to isophthalic acid is 9〇/10 to 6〇/4 ,, and the main diol component is r. The molar ratio of "terephthalic acid" and "isophthalic acid" of the polyester C-based acid component is 95 /5 to 80 /2 0, and the main diol component is "B. Alcohol. 2 · The multilayer polyester film of the first application of the patent scope, wherein the multilayer film has a crystal melting heat ΔHm of 20 to 60 (J/g) as measured by a DSC (differential scanning calorimeter). The multi-layered polyester film of claim 1, wherein the multi-layer film is a three-layer film composed only of the surface layer on both sides and the core layer held by the surface layer.