JPS62124927A - Rolled product of polyester film - Google Patents

Abstract

PURPOSE:To prevent aging wrinkle of a surface layer of a roll generating on a rolled product, by setting off moisture absorption elongation against heating shrinkage by controlling shrinkage characteristics at the specific temperature in the direction of a width of a film. CONSTITUTION:Monoaxial or biaxial stretching is applied to polyester after the same has been melted, cast over a cooling drum and cured through a cooling as a thin sheetlike thing, which is heat-treated and wound up further. In this instance, a film is left for 30min under dried air at the temperature of 105 deg.C as it is and a shrinkage factor in the direction of a width of the same is prepared so as to fall within a range of 0.8-2.0%. A polyester film controlled in this manner does not develop again wrinkle substantially even if the same is placed under circumstance wherein moisture absorption is performed as a rolled product. The reason why it is so is assumed that it is due to a matter that balance is kept on an extension and contraction actions in the direction of the width of the film.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a technique for preventing wrinkles that occur over time on the surface of 11 polyester products wound into a roll.

PRIOR ART Polynyster film 5y products with a thickness of 40 μm or less have the property of stretching in the width direction due to changes in the environment (moisture absorption) in which they are placed. This expanding fl quality is recognized as a change over time, and when such a dimensional change occurs, wrinkles are generated in a circumferential manner on the product surface in the longitudinal direction, and the corresponding area is printed during processing processes such as printing coating. This can cause defects such as misalignment and coating rings. In order to eliminate such drawbacks, there is a method of applying moisture-proof packaging to the roll surface to suppress dimensional changes due to environmental changes, or 1) - Adding sagging to the roll surface! There are known methods for absorbing dimensional changes. In the former case, there is an increase in cost due to the moisture-proof material, and in the latter case, other problems arise, such as horizontal wrinkles caused by the addition of slump, which reduce the operating rate in the processing process.

The present invention focuses on the fact that warp I) wrinkles that occur on film-wound products are mainly due to moisture absorption (water) expansion in the film width direction. This was achieved through new technical knowledge that attempts to offset the contraction in the width direction due to strain and the hygroscopic elongation behavior.

Therefore, in the present invention, the elongation which is predicted to be the cause of wrinkles over time and the residual strain (strain that recovers and shrinks to its original size over time) within a range that can be almost balanced are empirically adjusted. This residual strain is achieved by stretching the stretched and heat-set film by 1 to 3% in the width direction while winding it into one coil. Further, the amount of residual strain can be evaluated by a simple means of measuring the dry heat shrinkage rate.

That is, the amount of recovery from residual strain over time (shrinkage rate) can be predicted by the shrinkage rate obtained by exposing the film to dry heat air at 105°C for 30 minutes, and this dry heat shrinkage rate is 0.8.
If it is in the range of ~2.0%, the roll-shaped film y<y
It can be confirmed with good reproducibility that no wrinkles occur over time due to moisture absorption on the surface layers of the four products.

[Purpose of the invention] The present invention provides a method for forming a film having a thickness of 40 μm or less, preferably a thickness of 25 μm.
For the following polyester film-wound products, instead of using a winding method that imparts sag, or applying moisture-proof packaging, it is recommended to prevent wrinkles (vertical wrinkles) on the roll surface layer over time that occur on the roll product. purpose.

Structure of the Invention Vertical wrinkles on the roll surface layer that occur over time are particularly noticeable at high temperatures and high humidity. The film stretches in the middle direction due to environmental changes such as those described above, but when the roll surface film cannot absorb this dimensional change, flexure occurs, causing wrinkles on the roll surface.

The present invention is a method of adjusting the property of shrinkage of the film at a temperature slightly higher than the glass transition point (20 to 40° C. high temperature) to offset the moisture absorption elongation in the width direction of the film and the heat shrinkage. This was achieved by discovering the possibilities.

That is, the present invention provides 51 products made of polyester films having a thickness of 40 μm or less, and the dry heat shrinkage rate of the film at 105° C. is 0.8 to 2.0% in the width direction.
This is a polyester film-wrapped product that is wound into a roll, and is characterized by being in the range of .

The present invention will be explained.

The polyester that is the object of the present invention is one whose main component is polyethylene terephthalate, and which contains small amounts of copolymer components, heat stabilizers, lubricating additives, pigments, etc. in addition to the polyester. say something

This polynisdel is melted by a known method and casted onto a cooling drum as a thin sheet.
After being solidified, it is uniaxially or biaxially stretched by a known method, further heat treated if necessary, and wound up. In the present invention, a film having a thickness of 40 μm or less and having molecules oriented in the -axis or biaxial direction is targeted. When the film thickness exceeds 40 μm, wrinkles do not substantially occur in polyester. Therefore, the present invention provides 1 to
The target is relatively thin films ranging from ultra-thin films of about 4 μm to about 40 μm. Particularly prone to wrinkles 1
The present invention is particularly applicable to films having a diameter of .theta.T of .about.25 .mu.m.

When the film of the present invention is left in dry air at 105°C for 30 minutes, the shrinkage rate in the width direction is in the range of 0.8 to 2.0%, preferably in the range of 1.0 to 1.7%. is a requirement. A polyester film whose shrinkage rate at this temperature is adjusted to 0.8 to 2.0% is placed in an environment where it absorbs moisture as a rolled product, and substantially does not wrinkle over time due to moisture absorption. The reason for this is presumed to be that a balance is maintained in the expansion/contraction semi-OJ in the width direction of the film.

The shrinkage rate under such dry heat conditions of 105°C is 0.8 to 2.
0% can also be achieved by slightly tensioning (stretching) the film in the width direction with a stenter during stretching and heat setting, but it is important to check not only mechanical properties such as strong stretchability but also other physical properties. Since the color tube to be given is large, it is preferable to stretch the film that has been stretched and heat-set by about 1 to 3% in the width direction using a stenter or expander to achieve the desired target without impairing other physical properties. achieved.

More preferably, the elongation is performed below the glass transition point.

It seems that this slight deformation applied just before winding becomes residual strain and gives the film the property of being susceptible to shrinkage.

The wound product of the present invention is wound in a conventional manner, ie, under a suitable take-up (winding) tension on a core.

Example The present invention will be further explained below with reference to Examples.

(Example 1) Polyester was melted by a known method, cast on a cooling drum, cooled and solidified as a thin sheet, and then
After biaxial stretching and heat treatment by a known method, the film was stretched by 2.4% in the width direction in a heat setting zone to obtain a polyester film with a thickness of 10 μm. The film was slit to I+] 700 mm and wound under an appropriate winding tension to obtain a wound roll with a good appearance and no sagging on the surface layer. The roll was heated at 40°C x 100%
When the seedlings were allowed to sprout for 1 hour in the atmosphere of R1-1, there were no wrinkles on the surface layer.

The dry heat shrinkage rate of the film at 105° C. in the width direction for 30 minutes was 1.5%, and the strength and elongation at break in the transverse direction was 27 to 9/tntn, 120%. In addition, the dry heat shrinkage rate in the 111 direction at 150°C x 30 minutes is 5
．． It was 7%.

(Example 2) Two wheels were stretched in the same manner as in Example 1, and 4
．． After shrinking by 2%, the polyester film was stretched by 2.1% at the exit of the stenter and had a thickness of 10 μm. The film was slit by the same method as in Example 1, and rlJ
A 700 M roll with a good appearance and no sagging on the surface layer was prepared. When the roll was placed in an atmosphere of 100% R1-1 at 40° C. for 1 hour, there were no wrinkles on the surface layer.

Further, the roll was left in a natural environment at a temperature of 25 to 30° C. and a humidity of 50 to 80% RH for one month, but there were no wrinkles on the surface layer of the roll. When this film was left at 105° C. for 30 minutes, the dry heat shrinkage rate in the width direction was 1.0%. In addition, the breaking strength and elongation in the transverse direction are 2'3.4, 9/- and 15, respectively.
0% at 150°C (left for 30 minutes) 11
The directional dry heat shrinkage rate was 2.7%, compared to Comparative Example 1.
A physical property in which only the dry heat shrinkage rate in the rl+ direction at 05° C. (standing for 30 minutes) increased was iq.

(Comparative Example 1) A polyester film having a thickness of 10 μm after shrinking by 4.2% in the heat setting zone was obtained by biaxially stretching in the same manner as in Example 1. This film was slit in the same manner as in Example 1 to obtain a roll with a good appearance and no sagging on the middle 700 mm surface layer. This [1-R] at 40℃ (100% R
When the sample was left in an atmosphere of 1-1' for 1 hr, circumferential wrinkles were observed at a distance of 500 m from the surface layer. The dry heat shrinkage rate of this film in the width direction at 105°C < 30 minutes is 0.
．． It was 5%. In addition, the breaking strength and elongation in the transverse direction are 3
It was 0 Kg/mIA and 156%, and the medium direction dry heat shrinkage rate at 150° C. (30 minutes) was 2.5%.

Effects of the Invention The present invention has the effect of avoiding wrinkles that occur over time in film-wound products made of polyester.

Furthermore, the present invention does not require moisture-proof packaging, which has the advantage of simplifying the next process and the customer's packaging and storage process. Furthermore, since there is no need to loosen the surface layer of the roll during winding to create a rolled product, it is easy to handle the rolled product with a stable form, and there is no concern that the yield will decrease during the processing process.

Claims (3)

[Claims] (1) A rolled product made of a polyester film with a thickness of 40 μm or less, characterized in that the dry heat shrinkage rate of the film at 105°C is in the range of 0.8 to 2.0% in the width direction. A polyester film product that is wound into a roll. (2) A polyester film-wound product according to claim 1, which is obtained by stretching a biaxially stretched and heat-set polyester film with a thickness of 40 μm or less by 1 to 3% in the width direction, and then winding it up into a roll. . (3) Claim 1 or 2, which is a polyester film with a thickness of 25 μm or less, which has a dry heat shrinkage rate at 105° C. in the width direction of 1.0 to 1.7%. Polyester film-wrapped products listed in Section 1.