JP2001200074A - Heat-shrinkable polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a heat-shrinkable polyester film which has a good low- temperature shrinkability and can have a beautiful shrink finish almost free from wrinkles, pockmarks, and distortion on printed sections. SOLUTION: This polyester film satisfies the conditions represented by formula (1): 1<=β3/α3<=2,1<=β5/α5<=2, and 1<=β10/α10<=2 and formula (2): γ3<=γ5<=γ10 (wherein α3, α5, α10, β3, β5, β10, γ3, γ5, and γ10 are each defined in the specification).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a heat-shrinkable polyester film.

[0002]

2. Description of the Related Art Conventionally, polyvinyl chloride (PVC) films and polystyrene (P) have been used as heat-shrinkable films for packaging.
S) -based films and polyester-based films are known.

[0003] PVC films and PS films are made of PE
There is a problem in recyclability when used for T bottles and the like, and dioxin is generated at the time of incineration. Therefore, polyester films free of these problems have been attracting attention.

Many polyester films shrink more rapidly than PVC films and PS films, and are liable to cause shrinkage unevenness such as wrinkles and distortions, and have a problem in shrinkage characteristics.

Attempts have been made to improve the shrinkage unevenness of polyester films (Japanese Patent Laid-Open No. 5-261816).
In these, it was not possible to sufficiently reduce the shrinkage unevenness.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-shrinkable polyester film having a good low-temperature shrinkability and a beautiful shrink finish with less wrinkles, avatars and distortion of a printed portion. And

[0007]

SUMMARY OF THE INVENTION The present invention relates to the following heat-shrinkable polyester film. Item 1. Heat-shrinkable polyester film satisfying the following conditions 1 and 2:

[0008]

(Equation 5)

[0009] [alpha ₃ shows the main shrinkage direction of the heat shrinkage ratio after 3 seconds treatment at 70 ° C.; showing the main shrinkage direction of the heat shrinkage rate of 5 seconds after treatment with alpha ₅ 70 ° C.; alpha ₁₀ 70 ₃ shows the heat shrinkage in the main shrinkage direction after treatment at 10 ° C. for 10 seconds;
Shows the main shrinkage direction of the heat shrinkage ratio after second treatment; beta ₅ 80
Shows the heat shrinkage in the main shrinkage direction after treatment at 5 ° C. for 5 seconds; β ₁₀
Indicates the heat shrinkage in the main shrinkage direction after treatment at 80 ° C. for 10 seconds; γ ₃ indicates the heat shrinkage in the main shrinkage direction and a direction perpendicular to the main shrinkage direction (vertical direction) after treatment at 80 ° C. for 3 seconds. Γ ₅ indicates the main shrinkage direction after the treatment at 80 ° C. for 5 seconds and the heat shrinkage in the direction perpendicular to the main shrinkage direction (vertical direction); γ ₁₀ indicates the main shrinkage after the treatment at 80 ° C. for 10 seconds. Direction perpendicular to the contraction direction and the main contraction direction (vertical direction)
Item 2). Heat-shrinkable polyester film satisfying the following conditions 1 and 3:

[0010]

(Equation 6)

[Wherein α ₃ , α ₅ , α ₁₀ , β ₃ , β ₅ ,
β ₁₀ , γ ₃ , γ ₅ and γ ₁₀ are as defined above]. Item 3. Heat-shrinkable polyester film satisfying the following conditions 4, 5 and 6:

[0012]

(Equation 7)

Wherein α ₃ , α ₅ , α ₁₀ , β ₃ , β ₅ and β ₁₀ are as defined above. Item 4. Heat shrinkable polyester film satisfying the following condition 7:

[0014]

(Equation 8)

Wherein α ₃ , α ₅ , α ₁₀ , β ₃ , β ₅ and β ₁₀ are as defined above. Item 5. A resin comprising an intermediate layer containing more than 20% by weight of polybutylene terephthalate and / or a polybutylene terephthalate copolymer, and containing both sides of the intermediate layer and containing less than 20% by weight of polybutylene terephthalate and / or a polybutylene terephthalate copolymer Item 5. The heat-shrinkable polyester film according to any one of Items 1 to 4, having a layer. Item 6. The resin layer is more organic and / or
Item 6. The heat-shrinkable polyester film according to item 5, which contains an inorganic antiblocking agent.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In condition 1, β ₃ / α ₃ , β ₅
/ Α ₅ , β ₁₀ / α ₁₀ are preferably from 1 to 1.8, more preferably from 1 to 1.6, and still more preferably from 1 to 1.4.

Further, each difference between β ₃ / α ₃ , β ₅ / α ₅ and β ₁₀ / α ₁₀ (for example, (β ₃ / α ₃ ) − (β ₅ / α ₅ )) is ±
It is 0.6 or less, preferably ± 0.4 or less, more preferably ± 0.2 or less.

In condition 2, γ ₃ ≦ γ ₅ ≦ γ ₁₀ , preferably γ ₃ ≦ γ ₅ <γ ₁₀ , more preferably γ ₃ <γ ₅ <γ ₁₀
It is.

In condition 3, β ₃ / γ ₃ , β ₅ / γ ₅ , β
Of the group consisting of ₁₀ / gamma _10, a value obtained by dividing the minimum value maximum value, 2 or less, preferably 1.9 or less, more preferably 1.8 or less, more preferably 1.7 or less.

Under condition 4, α ₁₀ / α ₃ is 2.5 or less, preferably 2.3 or less, more preferably 2.1 or less, and further preferably 1.9 or less.

Under condition 5, α ₃ + α ₅ + α ₁₀ is 100 or more, preferably 102 or more, more preferably 104 or more, and further preferably 106 or more.

In condition 6, β ₃ + β ₅ + β ₁₀ is 190 or less, preferably 185 or less, more preferably 180 or less, and further preferably 175 or less.

In condition 7, (β ₃ + β ₅ + β ₁₀ ) /
(Α ₃ + α ₅ + α ₁₀ ) is preferably 1.1 to 2.0, more preferably 1.12 to 1.9, and still more preferably 1.1.
The film of the present invention having 4 to 1.8 is preferably a blend of two or more polyester-based films.

The ratio and amount of the polyester contained in the polyester film in a specific blend of two or more polyester films are shown below. (1) A polyester resin in which the dicarboxylic acid component is terephthalic acid (40 to 94 mol%), adipic acid (15 to 1 mol%), isophthalic acid (45 to 5 mol%), and the glycol component is ethylene glycol: 30 to 70 Parts by weight and dicarboxylic acid components are terephthalic acid (55-95 mol%) and isophthalic acid (45-5 mol%), and glycol components are ethylene glycol (70-95 mol%) and diethylene glycol (30-5 mol%). (2) an amorphous copolyester in which the dicarboxylic acid component is terephthalic acid, the glycol component is ethylene glycol (50 to 90 mol%), and cyclohexane dimethanol (50 to 10 mol%) Resin 25-55 parts by weight Dicarboxylic acid component is terephthalic acid, glycol component is ethylene Glycol (50 to 94 mol%), the polyester resin 55-25 neopentyl glycol (30-5 mol%) and diethylene glycol (20 to 1 mol%)
Parts by weight polybutylene terephthalate 40 to 10 parts by weight; (3)
10 to 80 parts by weight of an amorphous copolyester resin in which the dicarboxylic acid component is terephthalic acid, and the glycol component is ethylene glycol (50 to 90 mol%) and cyclohexane dimethanol (50 to 10 mol%) 10 parts by weight of polytetramethylene glycol % Copolymerized polybutylene terephthalate copolymer, 45 to 10 parts by weight, a dicarboxylic acid component containing terephthalic acid (55 to 95 mol%) and isophthalic acid (45 to 5 mol%), and a copolyester containing a glycol component of ethylene glycol 45 to 10 parts by weight of resin; the heat-shrinkable polyester film of the present invention may be a single-layer film made of a blend of the above-mentioned polyester films, but it is preferable to use polybutylene terephthalate and / or polybutylene terephthalate. Contains more than 20% by weight of polymer A laminated film of at least three layers having an intermediate layer and having on both sides of the intermediate layer a resin layer containing less than 20% by weight of polybutylene terephthalate and / or a polybutylene terephthalate copolymer is preferred.

In such a laminated film, the intermediate layer includes: an amorphous material in which the dicarboxylic acid component is terephthalic acid, the glycol component is ethylene glycol (50 to 90 mol%), and cyclohexanedimethanol (50 to 10 mol%). 10 to 80 parts by weight of a copolyester resin 50 to 20 parts by weight of a polybutylene terephthalate copolymer obtained by copolymerizing 1 to 40% by weight of polytetramethylene glycol and terephthalic acid (55 to 95% by mole) and isophthalic acid ( 45 to 5 mol%), and a blend of a polyester film composed of 50 to 10 parts by weight of a copolymerized polyester resin having a glycol component of ethylene glycol.

As a layer (resin layer) on both sides of the intermediate layer, an amorphous material in which the dicarboxylic acid component is terephthalic acid, the glycol component is ethylene glycol (50 to 90 mol%), and cyclohexanedimethanol (50 to 10 mol%) Of polybutylene terephthalate copolymer obtained by copolymerizing 20 to 89 parts by weight of a polycopolyester resin and 1 to 40% by weight of polytetramethylene glycol, and a dicarboxylic acid component containing terephthalic acid (55 to 95 mol%) and isophthalic acid A polyester film blend comprising an acid (45 to 5 mol%) and 50 to 10 parts by weight of a copolymerized polyester resin having a glycol component of ethylene glycol is exemplified.

The thickness of the intermediate layer is about 8 to 118 μm, and the thickness of both layers (resin layers) is about 1 to 30 μm.

The polybutylene terephthalate and / or polybutylene terephthalate copolymer is contained in the intermediate layer in an amount of more than 20% by weight, preferably 21 to 40% by weight, and in the resin layer, 2% by weight.
The content is less than 0% by weight, preferably 1 to 15% by weight.

The thickness of the film of the present invention is from 10 to 120
μm, preferably 20 to 70 μm.

The film of the present invention can be obtained by, for example, melt-extrusion by the T-die method and stretching the film in the transverse direction (shrinkage direction) about 3 to 6 times at a temperature of about 80 ° C. In the case of stretching, it is preferable to preheat at 80 ° C. ± 30 ° C. After stretching, it is preferable to anneal at a temperature of about 70 ° C. ± 15 ° C.

The average glass transition point of the polyester is 30
The temperature is about 90 ° C, preferably about 40 ° C to 80 ° C.

The intrinsic viscosity of the polyester is 0.5-1.
It is about 3 g / dl, preferably about 0.6 to 1.0 g / dl.

Examples of the antiblocking agent include wax, paraffin, silica, zeolite, talc and the like as an inorganic type, and PMMA as an organic type.

The amount of the anti-blocking agent is about 0.02 to 0.2% by weight based on the polyester resin.

[0035]

According to the present invention, the low-temperature shrinkability is good,
In addition, it is possible to obtain a heat-shrinkable polyester film having a beautiful shrinkage finish with less wrinkles, avatars and distortion of a printed portion.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments.

In the following Examples and Comparative Examples,
The shrinking finish in Table 8 was evaluated by shrinking the film attached to a commercially available 500 ml round PET bottle at a temperature of 200 ° C. for 7 seconds at a Kyowa Denki S200 tunnel at a passing time of 7 seconds and evaluating the width and the number of wrinkles generated. In Table 8, “◎” indicates wrinkles,
Indicates no avatar. "O" indicates that there is no wrinkle or avatar having a diameter of 1.0 mm or more. "△" is 2.0mm in diameter
This indicates that there are no more than two wrinkles and avatars of 4.0 mm or less. “X” indicates that there are three or more wrinkles and avatars having a diameter of 2.0 mm or more and 4.0 mm or less, or that there are wrinkles and avatars having a diameter of 4.0 mm or more. Example 1 A polyester resin in which the dicarboxylic acid component is terephthalic acid (83 mol%), adipic acid (6 mol%), isophthalic acid (11 mol%), and the glycol component is ethylene glycol (glass transition temperature 60 ° C., intrinsic viscosity 0) .75 g / d
l) 50 parts by weight of dicarboxylic acid component in terephthalic acid (8
5 mol%), isophthalic acid (15 mol%), and a copolymerized polyester resin having a glycol component of ethylene glycol (87 mol%) and diethylene glycol (13 mol%) (glass transition temperature 65 ° C, intrinsic viscosity 0.74 g /
dl) Using a polyester resin mixed with 50 parts by weight, melt extruding at 270 ° C. by a T-die method,
After preheating at 0 ° C., the film was tenter-stretched at 80 ° C. in the transverse direction by 4.0 times, and annealed at 70 ° C. ± 15 ° C. while relaxing at a relaxation rate of 2% to obtain a film having a thickness of 50 μm. Table 1 shows the shrinkage of this film. Example 2 Amorphous copolyester resin having a dicarboxylic acid component of terephthalic acid and a glycol component of ethylene glycol (70 mol%) and cyclohexanedimethanol (30 mol%) (glass transition temperature: 81 ° C., intrinsic viscosity: 0.76 g / d
l) Polyester resin having 40 parts by weight of dicarboxylic acid component as terephthalic acid, glycol component as ethylene glycol (80 mol%), neopentyl glycol (15 mol%) and diethylene glycol (5 mol%) (glass transition temperature 63 ° C., 40 parts by weight of intrinsic viscosity 0.78 g / dl and polybutylene terephthalate (glass transition temperature 21
A film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that a polyester resin mixed with 20 parts by weight of (° C., intrinsic viscosity 0.91 g / dl) was used. Table 1 shows the shrinkage of this film. Example 3 An amorphous copolyester resin having a dicarboxylic acid component of terephthalic acid and a glycol component of ethylene glycol (70 mol%) and cyclohexanedimethanol (30 mol%) (glass transition temperature: 81 ° C., intrinsic viscosity: 0.76 g / d
l) 50 parts by weight of polytetramethylene glycol
Wt% copolymerized polybutylene terephthalate copolymer (glass transition temperature 19 ° C, intrinsic viscosity 0.90 g / dl)
20 parts by weight, a copolyester resin having a dicarboxylic acid component of terephthalic acid (70 mol%) and isophthalic acid (30 mol%) and a glycol component of ethylene glycol (glass transition temperature: 71 ° C., intrinsic viscosity: 0.70 g / dl)
A film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that a polyester resin mixed with 30 parts by weight was used. Table 1 shows the shrinkage of this film. Example 4 An amorphous copolyester resin having a dicarboxylic acid component of terephthalic acid, a glycol component of ethylene glycol (70 mol%), and cyclohexane dimethanol (30 mol%) (glass transition temperature of 81 ° C.,
45 parts by weight of intrinsic viscosity (0.76 g / dl) and 25 parts by weight of a polybutylene terephthalate copolymer (glass transition temperature: 19 ° C., intrinsic viscosity: 0.90 g / dl) obtained by copolymerizing 10% by weight of polytetramethylene glycol, and dicarboxylic acid The components are terephthalic acid (70 mol%) and isophthalic acid (30
Mol%) and 30 parts by weight of a copolymerized polyester resin having a glycol component of ethylene glycol (glass transition temperature: 71 ° C., intrinsic viscosity: 0.70 g / dl). The acid component is terephthalic acid, the glycol component is ethylene glycol (70 mol%), the cyclohexane dimethanol (30
Mol%) of an amorphous copolyester resin (glass transition temperature: 81 ° C., intrinsic viscosity: 0.76 g / dl) and polytetramethylene glycol in an amount of 56% by weight and a polybutylene terephthalate copolymer (glass transition: 10% by weight). Copolymerized polyester resin (glass transition) having a temperature of 19 ° C., an intrinsic viscosity of 0.90 g / dl, 14 parts by weight, a dicarboxylic acid component of terephthalic acid (70 mol%) and isophthalic acid (30 mol%), and a glycol component of ethylene glycol. A polyester resin mixed with 30 parts by weight of a temperature of 71 ° C. and an intrinsic viscosity of 0.70 g / dl) was used, and the thickness of each layer was 1:
A film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that coextrusion was performed so that the ratio became 6: 1. Table 1 shows the shrinkage of this film. Comparative Example 1 A polyester resin having a dicarboxylic acid component of terephthalic acid (83 mol%), adipic acid (6 mol%), isophthalic acid (11 mol%), and a glycol component of ethylene glycol (glass transition temperature: 60 ° C., intrinsic viscosity: 0) .75 g / d
l) 50 parts by weight of an amorphous copolyester resin having a dicarboxylic acid component of terephthalic acid and a glycol component of ethylene glycol (70 mol%) and cyclohexanedimethanol (30 mol%) (glass transition temperature: 81 ° C., intrinsic viscosity: 0) (76 g / dl) A film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that a polyester resin mixed with 50 parts by weight was used. Table 1 shows the shrinkage of this film. Comparative Example 2 Amorphous copolyester resin having a dicarboxylic acid component of terephthalic acid and a glycol component of ethylene glycol (70 mol%) and cyclohexanedimethanol (30 mol%) (glass transition temperature: 81 ° C., intrinsic viscosity: 0.76 g / d
l) A film having a thickness of 50 μm in the same manner as in Example 1 except that a polyester resin obtained by mixing 75 parts by weight and 25 parts by weight of polyethylene terephthalate (glass transition temperature: 76 ° C., intrinsic viscosity: 0.72 g / dl) is used. I got Table 1 shows the shrinkage of this film. Comparative Example 3 Polyester resin having a dicarboxylic acid component of terephthalic acid and a glycol component of ethylene glycol (74 mol%), neopentyl glycol (16 mol%), and butanediol (10 mol%) (glass transition temperature 64 ° C., intrinsic viscosity) A film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that 0.73 g / dl) was used. Table 1 shows the shrinkage of this film.

Tables 2 to 7 are values calculated from Table 1.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

[0044]

[Table 6]

[0045]

[Table 7]

[0046]

[Table 8]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 67:00 C08L 67:00 F term (Reference) 4F071 AA33 AA43 AA45 AA71 AA83 AB26 AF61 BB06 BB07 BC01 BC17 4F210 AA24 AA25 AB07 AG01 AG03 RA03 RC02 RG02 RG04 RG09 RG43

Claims (6)

[Claims] 1. A heat-shrinkable polyester film satisfying the following conditions 1 and 2: [Alpha ₃ shows the main shrinkage direction of the heat shrinkage ratio after 3 seconds treatment at 70 ° C.; alpha ₅ shows the main shrinkage direction of the heat shrinkage rate after 5 seconds treatment at 70 ° C.; alpha ₁₀ at 70 ° C. 10 shows the main shrinkage direction of the heat shrinkage ratio after second treatment; beta ₃ is 80 ° C. in the following 3 seconds process in the main shrinkage direction showing a thermal shrinkage; beta ₅ is after 5 seconds treatment at 80 ° C. in the main shrinkage direction Shows heat shrinkage; β ₁₀ is 1 at 80 ° C.
Shows the main shrinkage direction of the heat shrinkage factor after 0 seconds processing; gamma ₃ is
The heat shrinkage in the main shrinkage direction and the direction perpendicular to the main shrinkage direction (vertical direction) after treatment at 80 ° C. for 3 seconds; γ ₅
Indicates the main shrinkage direction and the heat shrinkage in the direction perpendicular to the main shrinkage direction (vertical direction) after treatment at 80 ° C. for 5 seconds;
gamma ₁₀ shows a thermal shrinkage in a direction (vertical direction) perpendicular to the main shrinkage direction and the main shrinkage direction after 10 seconds treatment at 80 ° C.] 2. A heat-shrinkable polyester film satisfying the following conditions 1 and 3: Wherein α ₃ , α ₅ , α ₁₀ , β ₃ , β ₅ , β ₁₀ , γ ₃ , γ ₅ and γ ₁₀ are as defined above. 3. A heat-shrinkable polyester film satisfying the following conditions 4, 5 and 6: Wherein α ₃ , α ₅ , α ₁₀ , β ₃ , β ₅ and β ₁₀ are as defined above. 4. A heat-shrinkable polyester film satisfying the following condition 7: Wherein α ₃ , α ₅ , α ₁₀ , β ₃ , β ₅ and β ₁₀ are as defined above. 5. An intermediate layer containing more than 20% by weight of polybutylene terephthalate and / or polybutylene terephthalate copolymer, and polybutylene terephthalate and / or polybutylene terephthalate copolymer on both surfaces of the intermediate layer. The heat-shrinkable polyester film according to any one of claims 1 to 4, further comprising a resin layer containing less than about 10% by weight. 6. The resin layer contains an organic and / or inorganic anti-blocking agent in an amount larger than that of the intermediate layer.
4. The heat-shrinkable polyester film according to 1.