JPH0329763A - Fluorescent-lamp shrink packaging polyester film - Google Patents

Abstract

PURPOSE:To reduce wrinkling and distortion of a film, etc., at the time of shrink packaging and to contrive to improve working properties of the film by giving certain specific physical properties to a biaxially oriented film. CONSTITUTION:After polyester or copolymer polyester containing the proper quantity of inorganic particles, etc., as lubricant has been dried by the use of hopper dryer, paddle dryer, vacuum dryer, etc., the extraction of the polyester is performed at the temperature of 200-320 deg.C. Non-oriented film obtained by quenching after the extraction is first oriented 1.5-5.0 times uniaxially and then oriented 2.5-5.0 times in the direction perpendicularly intersection to the uniaxial direction so as to be gradually formed into a biaxially oriented film, and a heat treatment at 60-130 deg.C for 0.01-60 seconds is applied to the film. Thus, the film is prepared in such manner that the degree of face orientation (DELTAP) of the film is in the range of 0.070-0.150 on both surfaces of the film and the rate of shrinkage after treatment in 97 deg.C hot water for 30 seconds is 15-50% in one direction and the rate of shrinkage in the direction perpendicularly intersecting to the one direction is somewhat smaller than the former rate, i.e., 5-30% and the tear strength is 700g/mm or over.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a biaxially oriented polyester film for shrink wrapping fluorescent lamps. Specifically, the present invention has excellent performance in preventing glass fragments from scattering when fluorescent lamps are broken, has a beautiful appearance when shrink-wrapped, has uniform transparency, and is suitable for shrink-wrapping fluorescent lamps with excellent heat resistance. The present invention relates to a certain biaxially oriented polyester film.

[Means to solve the problem]

In view of the above-mentioned problems, the present inventors have made extensive studies and found that a biaxially oriented polyester film having certain physical properties has excellent properties as a film for shrink-wrapping fluorescent lamps, and has completed the present invention. I ended up doing it. In other words, the gist of the present invention is to improve the plane orientation degree (ΔP) of the film.
is 0 on both sides. 0 7 0~0. 150, and the shrinkage rate after treatment in hot water at 97°C for 30 seconds is 15 to 50% in one direction, and the shrinkage rate in the direction perpendicular to that direction is less than or equal to the shrinkage rate in the above direction. The present invention provides a polyester film for shrink-wrapping fluorescent lamps, characterized in that the polyester film is 5 to 30% and has a tear strength of 700 g/wall or more. The present invention will be explained in detail below. The polyester in the present invention may be a dicarboxylic acid such as terephthalic acid, schelaic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, etc. Consisting of one or more dicarboxylic acids, and diol ingredients such as ethylene glycol, neobentyl glycol, propylene glycol, 1,4-butanediol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, polyethylene glycol, etc. Any polyester or copolyester consisting of one or more types of known diols such as alkylene glycol and 1,4-cyclohexanedimethanol may be used.

Copolymerization ingredients include isophthalic acid, phthalic acid, adipic acid, sebacic acid, and 1,10-decanedicarboxylic acid as dicarboxylic acid ingredients, and neopentyl glycol, diethylene glycol, and polyalkylene glycol as diol ingredients, as necessary. 1. A copolyester using 4-cyclohexanedimethanol is preferred because it is industrially available at low cost and has good shrinkage characteristics. It is particularly preferable that the film of the present invention contains the above-mentioned copolyester component. The content of the copolymerized polyester component is preferably in the range of 3 to 50 mol%,
More preferably 5 to 40 mol%, particularly preferably 7 to 3
The range is 0 mol%. If the content of the copolymerized polyester component is less than 3 mol %, wrinkles, distortions, etc. will occur in the film during shrink processing, which is not preferable. On the other hand, if the content of the copolymerized polyester component exceeds 50 mol%, it is not preferable because the strength and solvent resistance of the film will be poor. Further, the above-mentioned polyester may be one in which other polymers are added or mixed in addition to the polyester, as long as it is not more than 30 wt%. Furthermore, in order to improve the slipperiness of the film, it is preferable to include fine particles such as organic lubricants and inorganic lubricants, and if necessary, stabilizers, colorants, antioxidants, antifoaming agents, and antistatic agents may be added. It may also contain additives such as agents. Fine particles that impart slipperiness include known inert external particles such as kaolin, clay, calcium carbonate, silicon oxide, calcium terephthalate, aluminum oxide, titanium oxide, calcium phosphate, lithium fluoride, carbon plaque, and polyester resin. Insoluble high melting point organic compounds during melt film formation, crosslinked polymers and metal compound catalysts used during polyester synthesis, such as alkali metal compounds,
Mention may be made of internal particles formed inside the polymer during polyester production by alkaline earth metal compounds and the like.

The fine particle content in the film is usually 0. 0 0 5～0
．． 9% by weight, and the average particle size is usually 0.9% by weight. O O
It is in the range of 1 to 3.5 μm. In the present invention, the heat of fusion of the film is preferably 1 to 8.
cal/g, more preferably in the range of 2 to 6 cal/g. If the heat of fusion of the film is less than lcal/g, it will be difficult to use the drying method normally used for polyethylene terephthalate in the drying process before extrusion film formation, which is undesirable. Further, a film having a heat of fusion exceeding 8 cal/g is not preferable because a sufficient shrinkage rate cannot be obtained. The intrinsic viscosity of the film of the present invention is preferably 0.50 or more, more preferably 0.60 or more, particularly preferably 0.6
It is 5 or more. If the intrinsic viscosity of the film is less than 0.50, crystallinity becomes high and sufficient shrinkage cannot be obtained, which is not preferable.

In the film of the present invention, it is necessary that the shrinkage rate after treatment in hot water at 97°C for 30 seconds is in the range of 15 to 50% in one direction of the film (hereinafter referred to as the main shrinkage direction), and preferably 17-45%, more preferably 20
~40% range.

If the shrinkage rate of the film in the main shrinkage direction is less than 15%, the amount of shrinkage will be insufficient during shrinkage processing, and the film will not adhere sufficiently to the fluorescent lamp, which is inappropriate. Furthermore, if the shrinkage rate in the main shrinkage direction of the film exceeds 50%, wrinkles, distortions, etc. will occur in the film during shrinkage processing, making it unsuitable. 97°C in a direction perpendicular to the main shrinkage direction of the film of the present invention
The shrinkage rate after treatment in hot water for 30 seconds must be less than the shrinkage rate in the main shrinkage direction and in the range of 5 to 30%, preferably less than the shrinkage rate in the main shrinkage direction and in the range of 7 to 30%. 2
5%, more preferably shrinkage rate in the main shrinkage direction or less and 1
It is in the range of 0-20%.

If the shrinkage rate is less than 5%, the amount of shrinkage will be insufficient during shrink wrapping, and the ends of the fluorescent lamp will not be wrapped well, resulting in poor processability, which is unsuitable. If the shrinkage rate in the direction perpendicular to the main shrinkage direction exceeds 30%, the amount of shrinkage in the longitudinal direction of the fluorescent lamp is too large during shrink wrapping, and the dimensions of the shrunk film will not match the longitudinal direction of the fluorescent lamp. It is inappropriate because it will disappear.

Further, in the film of the present invention, the ratio of the shrinkage rate (αl) in the main shrinkage direction to the shrinkage rate (α2) perpendicular to the main shrinkage direction, α1/α2, is 1. It is preferably in the range of 1 to 5.0, and 1.2 to 4. A range of 0 is more preferable, and 1.
A range of 3 to 3.5 is particularly preferred. α1/α2 is 1.
If it is less than 1, wrinkles, distortions, etc. will occur in the film during shrink wrapping, which is undesirable. On the other hand, if αl/α2 exceeds 5.0 in the film of the present invention, it is not preferable because the end portion of the fluorescent lamp cannot be wrapped well during shrink wrapping, resulting in poor processability.

Furthermore, it is necessary that the tear strength of the film of the present invention is 700 g/1 or more. Preferably 1000g/al
1 or more, more preferably 1500g/kil or more. If the tear strength of the film is less than 700 g/III, it is unsuitable because its function as a scattering prevention film will not be sufficient. The plane orientation degree (ΔP) of the film of the present invention is 0.0 on both sides.
0 7 0~0. It needs to be in the range of 150, preferably 0.080-0. 1 4
0, more preferably 0. 0 8 5~0. 1 3
The range is 0. ΔP is 0. 0 7 If less than 0,
This is unsuitable because the shatterproof properties of the shrink wrapping film will not be sufficient. On the other hand, ΔP is 0. If it exceeds 150, it is not suitable because it will cause shrinkage, wrinkles, distortion, etc. on the film. In addition, in the present invention, the degree of plane orientation (ΔP,) on one side of the film and the degree of plane orientation (ΔP,) on the opposite side of the film are also determined.
P2), that is, 1ΔP1−Δp. I is 0.
It is preferable that it is 0.5 or less. More preferably 0. 0 4 0 or less, particularly preferably 0.0
20 or less. 1ΔP1−Δpg I is 0. 0
If it exceeds 50, wrinkles, distortions, etc. will occur in the film during shrinkage processing, and the shatterproof property will not be sufficient when the fluorescent lamp is damaged, which is not preferable.

The thickness unevenness in the longitudinal direction of the film of the present invention is preferably 30% or less. It is more preferably 25% or less, particularly preferably 20% or less. If the thickness unevenness of the film exceeds 30%, wrinkles and distortions may occur in the film during shrinkage processing, and the transparency of the film may become uneven, which not only impairs the appearance of the packaged fluorescent lamp, but also makes it difficult to use the fluorescent lamp. This is not desirable because the intensity of the irradiated light becomes uneven when the light is turned on. The haze value of the film of the present invention is preferably 10% or less,
More preferably it is 7% or less, particularly preferably 5% or less. If the haze value exceeds 10%, the intensity of the irradiated light will be weakened when the fluorescent lamp is turned on, which is not preferable. In addition, a foaming ink layer is printed on one or both sides of the film of the present invention, or a thermoplastic resin film or sheet with bubbles inside is laminated to provide cushioning properties, so that it can be used in the event of damage to a fluorescent lamp. It is also possible to further improve the performance of preventing scattering of fragments. Such thermoplastic resins include polyvinyl chloride, polyethylene, polypropylene, polyacrylic, polystyrene, polyester, etc.
Any known thermoplastic resin can be used. Next, the method for producing the film of the present invention will be specifically explained, but the present invention is not particularly limited to the following production method unless it exceeds the gist thereof.

Polyester or copolyester containing an appropriate amount of inorganic particles as a lubricant, if necessary, is dried using an ordinary hopper dryer, paddle dryer, vacuum dryer, etc., and then extruded at a temperature of 200 to 320°C. After extrusion, the film is rapidly cooled to obtain an unstretched film. When the T-die method is used, a film with uniform thickness can be obtained by using a so-called electrostatic application adhesion method during the rapid cooling.

The unstretched film obtained in this way is first uniaxially (
Stretched 1.5 to 5.0 times in the longitudinal direction (usually the longitudinal direction), then 2.5 to 5.0 times in the direction perpendicular to the longitudinal direction. Stretch 0 times to make a sequentially biaxially stretched film. The film stretched in this way has a temperature of 60 to 130°C.
So 0. Heat treatment is performed for 60 seconds. Heat treatment is usually carried out under tension fixation, but it is also possible to loosen or widen the material by 20% or less at the same time. As the heat treatment method, known methods such as a method in which the material is brought into contact with a heating roll or a method in which the material is gripped by a clip in a tenter can be used. Further, it is also possible to perform re-stretching after heat treatment.

It is also possible to perform a corona discharge treatment on one or both sides of the film during, before, or after the stretching process to improve the adhesion of the film to the printed layer or the like.

It is also possible to improve the adhesion, antistatic properties, slipperiness, light-shielding properties, etc. of the film by coating one or both sides of the film during, before, or after the stretching process.

The film thus obtained is rolled up and made into a product. The thickness of the film obtained as described above is not particularly limited, but the thickness preferably used as a shrink wrapping film for fluorescent lamps is in the range of 10 to 300 μm,
Particularly preferred is a range of 20 to 200 μm. [Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples unless it goes beyond the gist thereof. The method for evaluating the film is shown below. (1) Intrinsic viscosity of film [η] Sample 200cm was mixed with phenol/tetrachloroethyl 7=50
750 mixed solvent 20mj! In addition, the temperature was measured at 30°C after heating at about 110°C for 1 hour. (2) Degree of planar orientation (ΔP) Measurement was performed using an Appe refractometer manufactured by Atago ■ and a sodium lamp as the light source. Note that the measurements were performed on both sides of the film.

The maximum refractive index n7 in the film plane, the refractive index nβ in the direction perpendicular to it, and the refractive index nα in the thickness direction were determined, and the degree of plane orientation was calculated. 2 (3) Shrinkage rate The shrinkage rate was calculated using the following formula by heat-treating the film in hot water at 97°C for 30 seconds under no tension and measuring the length of the film before and after the treatment. (4) Haze The haze value of the film was measured according to JIS K6714 using a sphere-splitting turbidity meter NDH-200 manufactured by Nippon Denshoku Industries. (5) Tear strength (g/kaku) Required to tear a sample film for 50 mm using a light load tear tester manufactured by Toyo Seiki Co., Ltd. according to the method described in ASTM D1922 with a diameter of 50 m and a length of 63.5 mm. The load was measured and divided by the film thickness (Inflll) to obtain the tear strength. (6) Shrinkage characteristics of the film (wrinkles, distortion, and workability) The sample film was wound so that its main shrinkage direction was along the radial direction of the fluorescent lamp, and made into a cylindrical bag with a diameter of 34 m using adhesive. After that, it was placed over a fluorescent light and passed through a shrink tunnel to shrink. To evaluate the finish of the shrink wrap, wrinkles and distortion were visually judged as ○, Δ, and ×. ○ indicates that almost no defects are observed, Δ indicates that some defects are observed but can be put into practical use, and × indicates that many defects are observed and cannot be put into practical use.

In addition, the workability was evaluated as follows. ○ indicates that the end of the fluorescent light is wrapped well, and × means that the end of the fluorescent light is not wrapped well. (7) Drop scattering test After dropping a fluorescent lamp shrink-wrapped sample film onto the floor from a height of 2.0 m, the following evaluation was made based on the distance that glass fragments were scattered. In addition, the above evaluation item (7). (8). Considering (9) comprehensively, we gave an overall evaluation of ○ or ×. Example 1 Terephthalic acid 841101% as dicarboxylic acid component,
The average particle size is 1.5 mol% of isophthalic acid units and ethylene glycol units as the diol component. Contains 300 ppm of 3 μm amorphous silica [η)
=0.71 copolymerized polyester was pre-crystallized at 120°C for 4 hours, dried at 180''C for 4 hours, then melted at 290°C with an extruder, extruded through a T-die, rapidly solidified, and unstretched. A sheet was obtained. The unstretched sheet was rolled 3 times in the longitudinal direction using a heated roll at 85°C.
．． After stretching 2 times, it is introduced into a tenter and stretched at 90°C for 3 times in the transverse direction.
．． Stretching was performed 6 times, followed by heat treatment at 105° C., and after cooling, the film was wound up to obtain a sequentially stretched two-wheel film having an average thickness of 100 um.

Example 2 Consisting of terephthalic acid units as the dicarboxylic acid component and 82.5 mo of ethylene glycol units as the diol component
l%, neopentyl glycol units 12.5 mol%,
Consisting of 5-Ol% diethylene glycol units, [η
) = 0.65 copolymerized polyester and average particle size 1.0
Contains 1000 ppm of μm amorphous silica (η)=0.
70 polyethylene terephthalate at a weight ratio of 60/4
After blending at a ratio of 0, dry in exactly the same manner as in Example 1,
An unstretched sheet was obtained by extrusion and rapid solidification. The unstretched sheet was rolled in the longitudinal direction by heating rolls at 85°C.
．． After stretching 2 times, it is introduced into a tenter and stretched at 90°C for 3 times in the transverse direction.
．． Stretched 6 times, followed by heat treatment at 95°C,
After cooling, the film was wound up to obtain a sequentially biaxially stretched film with an average thickness of 100 μm. Comparative Example 1 The unstretched sheet of Example 1 was directly introduced into a tenter and stretched 3.0 times in the transverse direction at 90°C, followed by heat treatment at 105°C, and after cooling, it was rolled up to form a uniaxially stretched film with an average thickness of 100 μm. Obtained. Comparative Example 2 Terephthalic acid 8411101% as dicarboxylic acid component
, containing 1000 ppm of amorphous silica with an average particle size of 7.5 μm, consisting of 1% of isophthalic acid units l6IlO and ethylene glycol units as diol part [η)
-0.70 copolymerized polyester was dried in a conventional manner, then melted at 285°C in an extruder and extruded through an annular die.
After cooling, a tubular unstretched sheet was obtained. Pressurized gas is injected from the end of the tubular unstretched sheet, and 9
At 0°C setting, it is expanded 3.6 times in the radial direction, and at the same time, it is expanded 3.6 times in the axial direction using a differential speed roll.
The film was stretched once, then heat-treated at 105° C., cooled, and then wound to obtain a two-wheel simultaneous tubular stretched film with an average thickness of 100 μm.

The results obtained above are summarized in Table 1.

〔Effect of the invention〕

The film of the present invention has extremely few wrinkles, distortions, etc. during shrink wrapping, and has excellent shrinkage characteristics that make it easy to process.It also has excellent properties to prevent glass fragments from scattering when a fluorescent lamp is broken, and This is a film with extremely high industrial value for use in light shrink packaging.

Claims (1)

[Claims] (1) The plane orientation degree (ΔP) of the film is 0.07 on both sides.
0 to 0.150, and the shrinkage rate after treatment in 97°C hot water for 30 seconds is 15 to 50% in one direction, and the shrinkage rate in the direction perpendicular to the said direction is the shrinkage rate in the said direction. or less and 5 to 30%, and the tear strength is 700g/
A polyester film for shrink-wrapping fluorescent lamps, which is characterized by having a film size of 1 mm or more.