JPH068322A - Heat shrinkable polyester film - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a heat-shrinkable polyester film having a relatively high shrinkage ratio and having practically no uneven shrinkage and having excellent practicality. [Structure] A dicarboxylic acid component having an aromatic dicarboxylic acid or an ester-forming derivative thereof as a main component and a diol component having an ethylene oxide adduct of ethylene glycol and a bisphenol compound or its derivative as a main component, and a bisphenol A ethylene oxide addition compound. The content of the product is 0.1 to 50 mol% in all the diol components, and polyoxytetramethylene glycol and / or polyethylene glycol is contained in the resin in an amount of 0.1 to 50 mol%.
A heat-shrinkable polyester film containing 20 to 20% by weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-shrinkable polyester film used for various packaging materials, and more specifically, it has a high shrinkage ratio and excellent heat shrinkage characteristics such as uneven shrinkage. The present invention relates to a polyester film having the same.

[0002]

2. Description of the Related Art Heat-shrinkable plastic films are used for marking and protecting containers, fishing rods, condensers, rod-shaped fluorescent lamps, etc.
It is used for bundling and improving the added value of products, and is also used for the integrated packaging of books and notebooks and the close packaging. At present, it is expected to develop various applications in many other fields by utilizing the shrinkability and shrinkage stress of the heat-shrinkable film.

Conventionally, resins such as polyvinyl chloride, polystyrene, and polyolefin have been used as the material for the heat-shrinkable plastic film. However, such resins have problems in heat resistance, weather resistance, chemical resistance and the like. For example, although polyvinyl chloride film can be used as a heat-shrinkable film having various shrinkage characteristics, fish eyes are likely to occur frequently, and the product printed with this film has a poor aesthetic appearance and a reduced commercial value. It was easy to become what I did. In addition, excessive quality control is required to obtain a heat-shrinkable film without fish eyes, which causes a problem that the film manufacturing cost is significantly increased. Furthermore, polyvinyl chloride causes pollution problems when incinerated at the time of disposal, and additives such as plasticizers in polyvinyl chloride resin bleed out over time, causing dirt due to adhesion of dust, etc. Also, it was not preferable.

On the other hand, a heat-shrinkable film obtained from polystyrene has a good finish after shrinkage, but has a low solvent resistance, so that a special ink must be used for printing, and even at room temperature. It had to be stored in a cool place due to spontaneous shrinkage. In addition, there is a big problem in the disposal because it needs to be incinerated at a high temperature and a large amount of black smoke and a strange odor are generated during the incineration. As a material capable of solving these problems, polyester film is highly expected, and its usage amount has been remarkably increasing.

[0005]

However, the conventional heat-shrinkable polyester film has not been sufficiently satisfactory in its heat-shrinkable property. In particular, uneven shrinkage is likely to occur at the time of shrinking, when covering and shrinking a container such as a bottle,
There were problems such as the characters and patterns printed on the film being distorted and the adhesion of the film to the container being insufficient.

[0006]

The inventors of the present invention have arrived at the present invention as a result of earnestly examining the heat shrinkage behavior of a polyester film in view of such circumstances.
That is, the heat-shrinkable polyester film of the present invention,
An aromatic dicarboxylic acid or a dicarboxylic acid component containing an ester-forming derivative as a main component and a diol component containing ethylene glycol and a bisphenol compound or an ethylene oxide adduct of a derivative thereof as a main component,
The content of ethylene oxide adduct of bisphenol compound or its derivative is 0.1 to all diol components.
It is characterized by containing 0.1 to 20% by weight of polyoxytetramethylene glycol and / or polyethylene glycol in addition to 50 mol%.

The polyester resin used in the heat-shrinkable polyester film of the present invention comprises an aromatic dicarboxylic acid or its ester-forming derivative as a main component as a dicarboxylic acid component, and ethylene glycol and a bisphenol compound or its ethylene oxide as a diol component. The main component is an adduct and also polyoxytetramethylene glycol and / or polyethylene glycol.

In the present invention, examples of the aromatic dicarboxylic acid which is the main component of the dicarboxylic acid component constituting the polyester resin include terephthalic acid, isophthalic acid, naphthalene-1,4- or -2,6-dicarboxylic acid. To be Further, examples of these ester derivatives include derivatives such as dialkyl esters and diaryl esters. The aromatic dicarboxylic acid or its ester-forming derivative is preferably contained in the dicarboxylic acid component in an amount of 80 mol% or more, more preferably 85 mol%.
It is the above range. This is because if the content of the aromatic dicarboxylic acid or its ester-forming derivative is less than 80 mol%, the mechanical strength of the formed polyester film may be reduced.

In the polyester resin of the present invention, for the purpose of enhancing the effect of the present invention and increasing the amount of heat shrinkage, an aliphatic dicarboxylic acid or ester derivative thereof other than the above is less than 20 mol%, preferably less than 15 mol%. You may make it contain in the range of. This is because if these aliphatic dicarboxylic acids are contained in an amount of 20 mol% or more, the mechanical properties of the film deteriorate. Examples of the aliphatic dicarboxylic acid that can be used in the present invention include glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid and succinic acid.

The diol component constituting the polyester resin of the present invention comprises ethylene glycol and an ethylene oxide adduct of a bisphenol compound or its derivative as a main component, and the ethylene oxide adduct of a bisphenol compound or its derivative is 0 in all diol components. .1
It is necessary to be contained in the range of 50 to 50 mol%, preferably 0.5 to 30 mol%. This is because if the content of the ethylene oxide adduct of the bisphenol compound or its derivative is less than 0.1 mol%, there is no effect of reducing shrinkage unevenness, and conversely, if it exceeds 50 mol%, the low temperature shrinkability decreases. Is. Examples of the ethylene oxide adduct of the bisphenol compound or its derivative include those having the structures represented by the following general formulas (1) and (2).

[0011]

[Chemical 1]

(In the formula, X is CH ₂ , C (CH ₃ ) ₂ , C
(CF ₃ ) ₂ , O, S and SO ₂ , n and m
Satisfies 2 ≦ n + m ≦ 6. )

[0013]

[Chemical 2]

(In the formula, X is CH ₂ , C (CH ₃ ) ₂ , C
(CF _{3) 2,} O, S and SO _2, R is C ₁ -C ₅
Is an alkyl group or a halogen group, and n and m are
2 ≦ n + m ≦ 6 is satisfied, and a and b are integers of 1 to 4. Among these, an ethylene oxide adduct of bisphenol A having the structure of the following general formula (3) is preferable.

[0015]

[Chemical 3]

(In the formula, n and m satisfy 2 ≦ n + m ≦ 6.) Further, in the present invention, polyoxytetramethylene glycol and //, together with ethylene glycol and bisphenol A ethylene oxide adduct as diol components. Alternatively, it may contain polyethylene glycol. By containing polyoxytetramethylene glycol and / or polyethylene glycol, excellent effects can be obtained by reducing the shrinkage unevenness of the heat shrinkable film. These polyoxytetramethylene glycol or polyethylene glycol are added to the resin in an amount of 0.
The content is preferably in the range of 1 to 20% by weight, more preferably 0.3 to 15% by weight. This is because when the content of the polyoxytetramethylene glycol or polyethylene glycol component is less than 0.1% by weight, the effect of reducing shrinkage unevenness is small, and when it exceeds 20% by weight, the melting point and glass transition temperature of the resin become low. This is because the film forming property is inferior. The molecular weight of polyoxytetramethylene glycol used is preferably in the range of 300 to 4000, and the molecular weight of polyethylene glycol is 300.
It is preferably in the range of up to 20000. This is because those having a molecular weight less than this do not show the effect of reducing uneven shrinkage, and conversely,
This is because if the molecular weight exceeds this range, the compatibility with the resin is poor and it is not preferable.

Further, in the present invention, propylene glycol, triethylene glycol, butylene glycol, diethylene glycol, neopentyl glycol, cyclohexane dimethanol and the like can be used as the diol component within a range not impairing the effect of the present invention. The polyester resin in the present invention can be produced by a known direct polymerization method, transesterification method, or the like, and the degree of polymerization thereof is not particularly limited, but the intrinsic viscosity (phenol / phenol / 0.5 to 0.5) in a mixed solution of tetrachloroethane and the like at 25 ° C.
The thing of 1.2 is preferable.

The obtained polyester resin is formed into a film original film by a known film forming method such as a casting roller method or a calendar method. Then, the raw film is placed at 3 ° C from the glass transition temperature of the polyester resin.
1.5 to 5.0 times in the vertical or horizontal direction, preferably 1.5 to
The film is stretched 4.8 times to give a high shrinkage factor to the film.
Further, if necessary, 1.0 in the direction perpendicular to the stretching direction.
It is stretched to a stretch ratio of 1.8 to 1.8 times, preferably 1.0 to 1.5 times.
This is effective in increasing the tensile strength of the film and preventing shrinkage in the stretching direction more than necessary. The stretching of the film is performed by a method such as simultaneous biaxial stretching, sequential biaxial stretching, uniaxial stretching, etc. Either of the longitudinal stretching and the transverse stretching may be performed first.

The stretched heat-shrinkable polyester film can be used as it is as a product,
From the viewpoint of dimensional stability, the heat treatment may be performed at a temperature of 50 to 150 ° C. for several seconds to several tens of seconds. By carrying out such heat treatment, preferable properties such as adjustment of the shrinkage ratio in the shrinking direction of the polyester film of the present invention, reduction of shrinkage over time during storage of the unshrinked film, reduction of shrinkage unevenness, etc. can be exhibited.

The thickness of the heat-shrinkable polyester film of the present invention is not particularly limited, but it is 1 to 600 μm.
Those in the range of are practically used. 6 to 380 μm for packaging applications, especially packaging of foods, beverages, pharmaceuticals, etc.
Those in the range of are used. When used for labels such as PET bottles and glass bottles, those having a range of 20 to 70 μm are used.

The present invention may be subjected to various conventionally known processing treatments or may be blended with suitable additives in order to impart more specific performance. Examples of processing treatments include irradiation with ultraviolet rays, α rays, β rays, γ rays or electron beams, corona treatment, plasma irradiation treatment, flame treatment, vinylidene chloride, polyvinyl alcohol, polyamide, polyolefin, etc. Examples thereof include resin coating, laminate, and metal vapor deposition. Examples of additives include polyamide, polyolefin, polymethylmethacrylate, resins such as polycarbonate, silica, talc, kaolin, inorganic particles such as calcium carbonate, titanium oxide, pigments such as carbon black, ultraviolet absorbers, release agents, and the like. Flame retardants and the like can be mentioned.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples. The shrinkage ratio in the examples is 150 m in the stretching direction.
m, polyester film cut to a size of 20 mm in the direction perpendicular to the m
The film was heated in 0 ° C. and 100 ° C. hot air for 60 seconds with no load, and the length before shrinkage (L) and the length after shrinkage (L ′) were measured in the stretching direction of the film. Sought by. Shrinkage rate (%) = {(L−L ′) / L} × 100 Heat unevenness is 150 mm in the stretching direction and 2 in the direction perpendicular to the stretching direction.
A polyester film cut into a size of 0 mm
After heat-shrinking in a warm air of 100 ° C. for 30 seconds with no load, the occurrence of shrinkage unevenness on the film was evaluated on the appearance according to the following three-stage criteria. ◯: Almost no shrinkage unevenness was found Δ: Little shrinkage unevenness was generated ×: Significant shrinkage unevenness In addition, as the ethylene oxide adduct of the bisphenol compound or its derivative in the following examples, The ethylene oxide of bisphenol A represented by the general formula (3) or the ethylene oxide adduct of bisphenol S represented by the general formula (1) having n + m = 2 was used.

Example 1 100 parts by mole of terephthalic acid, 2 parts by mole of bisphenol A ethylene oxide adduct, ethylene glycol 147
A molar part and 10% by weight of polyoxytetramethylene glycol (molecular weight 1000) (relative to the polymer) were placed in a reaction vessel, and 450 ppm of antimony trioxide as a polymerization catalyst was added to all acid components, and polymerization was carried out by a direct polymerization method.
The obtained polyester resin was melt extruded at 270 ° C. to prepare a raw film. This raw film was uniaxially stretched 3.8 times in the stretching direction (TD direction) at 65 ° C. to obtain a heat-shrinkable polyester film having a thickness of 35 μm. Table 1 shows the measurement results of the shrinkage rate of the obtained film and the evaluation results of the shrinkage unevenness.

Example 2 100 mol parts of dimethyl terephthalate, 30 mol parts of bisphenol A ethylene oxide adduct, 148 mol parts of ethylene glycol and 20% by weight of polyethylene glycol (molecular weight 10,000) (to polymer) were placed in a reaction vessel, and an ester exchange catalyst was added. As zinc acetate, 350 ppm to all acid components, germanium dioxide as a polymerization catalyst, 450 ppm to all acid components, and trimethyl phosphate as a stabilizer, 350 ppm to all acid components were added and polymerized by the transesterification method. . The obtained polyester resin was melt extruded at 270 ° C. to prepare a raw film. This raw film is stretched at 60 ° C. in the stretching direction (TD
Direction) was uniaxially stretched 3.8 times to obtain a heat-shrinkable polyester film having a thickness of 35 μm. Table 1 shows the measurement results of the shrinkage rate of the obtained film and the evaluation results of the shrinkage unevenness.

Example 3 90 mol parts of terephthalic acid, 10 mol parts of isophthalic acid, 0.3 mol parts of bisphenol A ethylene oxide adduct, 141 mol parts of ethylene glycol and 0.1% by weight of polyoxytetramethylene glycol (molecular weight 650).
(Polymer) was placed in a reaction vessel, polymerized and stretched in the same manner as in Example 1 to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the measurement results of the shrinkage rate of the obtained film and the evaluation results of the shrinkage unevenness.

Example 4 83 mol parts of terephthalic acid, 17 mol parts of isophthalic acid, 45 mol parts of bisphenol A ethylene oxide adduct,
100 parts by mol of ethylene glycol and 12% by weight of polyethylene glycol (molecular weight 300) (relative to the polymer) were placed in a reaction vessel, and 450 ppm of germanium dioxide as a polymerization catalyst was added to all the acid components, followed by direct polymerization. The polyester resin thus obtained was treated in the same manner as in Example 1 to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the measurement results of the shrinkage rate of the obtained film and the evaluation results of the shrinkage unevenness.

Example 5 90 mole parts of terephthalic acid, 10 mole parts of isophthalic acid, 10 mole parts of bisphenol S ethylene oxide adduct,
150 mol parts of ethylene glycol and 5% by weight of polyethylene glycol (molecular weight 300) (relative to polymer) were put in a reaction vessel, trimethyl phosphate as a stabilizer was 50 ppm with respect to the total acid component, and germanium dioxide as a polymerization catalyst was the total acid component. On the other hand, 450 ppm was added, and polymerization was carried out by the direct polymerization method. The obtained polyester resin was melt extruded at 270 ° C. to prepare a raw film. This film was uniaxially stretched 3.8 times in the stretching direction (TD direction) at 70 ° C. to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the measurement results of the shrinkage rate of the obtained film and the evaluation results of the shrinkage unevenness.

Comparative Example 1 100 parts by mole of terephthalic acid and 150 parts of ethylene glycol
A molar part was placed in a reaction vessel, and germanium dioxide as a polymerization catalyst was 450 ppm with respect to all acid components, and trimethyl phosphate as a stabilizer was 350 p with respect to all acid components.
pm was added and polymerization was carried out by the direct polymerization method. The obtained polyester resin was melt extruded at 270 ° C. to prepare a raw film. This raw film was uniaxially stretched 3.8 times in the stretching direction (TD direction) at 85 ° C. to obtain a thickness of 40 μm.
A heat-shrinkable polyester film of m was obtained. Table 1 shows the measurement results of the shrinkage rate of the obtained film and the evaluation results of the shrinkage unevenness.

Comparative Example 2 100 mol parts of dimethyl terephthalate, 140 mol parts of ethylene glycol and polyethylene glycol (molecular weight 1
000) 70% by weight (relative to polymer) was placed in a reaction vessel,
Polymerization was carried out in the same manner as in Example 2, but the obtained polyester resin was inferior in heat resistance and could not be formed into a film.

Comparative Example 3 100 mol parts of terephthalic acid, 100 mol parts of bisphenol A ethylene oxide adduct, 1 part of ethylene glycol
100 parts by weight of polyoxytetramethylene glycol (molecular weight 1000) 10% by weight (against polymer) were placed in a reaction vessel, antimony trioxide was used as a polymerization catalyst in an amount of 450 ppm, and trimethyl phosphate was used as a stabilizer in the total acid. Although 350 ppm was added to the components and polymerization was performed by the direct polymerization method, the degree of polymerization did not increase during the polymerization, and the polyester resin was not used for forming a film.

Comparative Example 4 90 mole parts of terephthalic acid, 10 mole parts of isophthalic acid, 20 mole parts of bisphenol A ethylene oxide adduct,
130 mol parts of ethylene glycol was placed in a reaction vessel, trimethyl phosphate as a stabilizer was added in an amount of 200 ppm to all acid components, and germanium dioxide as a polymerization catalyst was added in an amount of 400 ppm to all acid components, followed by direct polymerization. The obtained polyester resin was melt extruded at 270 ° C. to prepare a raw film. This film was uniaxially stretched 3.8 times in the stretching direction (TD direction) at 65 ° C. to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the measurement results of the shrinkage rate of the obtained film and the evaluation results of the shrinkage unevenness.

Comparative Example 5 83 mol parts of terephthalic acid, 17 mol parts of isophthalic acid, 130 mol parts of ethylene glycol and 5% by weight of polytetraoxymethylene glycol (molecular weight 2000) (to polymer) were placed in a reaction vessel, and trimethyl was used as a stabilizer. Phosphate 200ppm for all acid components, germanium dioxide as a polymerization catalyst 400pp for all acid components
m was added and polymerization was carried out by the direct polymerization method. The obtained polyester resin was melt extruded at 270 ° C. to prepare a raw film. This film was uniaxially stretched 3.8 times in the stretching direction (TD direction) at 65 ° C. to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the measurement results of the shrinkage rate of the obtained film and the evaluation results of the shrinkage unevenness.

[0033]

[Table 1]

The components shown in the table are as follows.

TPA: terephthalic acid IPA: isophthalic acid EG: ethylene glycol BPAE: bisphenol A ethylene oxide adduct BPSE: bisphenol S ethylene oxide adduct PEG: polyethylene glycol PTMG: polyoxytetramethylene glycol Examples 1 to 3 of the present invention As shown in Table 1, the heat-shrinkable polyester film of No. 5 has 30% or more at 80 ° C. and 10
At 0 ° C., it showed a shrinkage ratio of 40% or more, and almost no uneven shrinkage was observed. On the other hand, the heat-shrinkable polyester films of Comparative Examples 1, 4 and 5 have a large shrinkage ratio,
It was inferior in practical use due to uneven shrinkage.

[0036]

EFFECT OF THE INVENTION The heat-shrinkable polyester film of the present invention has a relatively high heat-shrinkage rate and hardly causes uneven shrinkage, and is excellent in practicality as various packaging materials.

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Claims (2)

[Claims] 1. A dicarboxylic acid component containing an aromatic dicarboxylic acid or an ester-forming derivative thereof as a main component, and a diol component containing ethylene glycol and a bisphenol compound or an ethylene oxide adduct of a derivative thereof as a main component. The solicitation amount of the ethylene oxide adduct of the derivative is 0.1 to 50 mol% in all diol components, and 0.1 to 20 wt% of polyoxytetramethylene glycol and / or polyethylene glycol is contained. Heat shrinkable polyester film. 2. An ethylene oxide adduct of a bisphenol compound or a derivative thereof is an ethylene oxide adduct of bisphenol A.
The heat-shrinkable polyester film described.