JPS60178031A - Preparation of very thin polyethylene terephthalate film - Google Patents

Abstract

PURPOSE:To prevent orienting film from breaking by a method wherein a laminated oriented sheet of polyethylene terephthalate and propylene copolymer having a specified properties are heat-treated at a specified temperature and then cooled to peel them from each other. CONSTITUTION:Polyethylene terephthalate with intrinsic viscosities 0.55-0.75dl/g and propylene copolymer with intrinsic viscosities 1.0-2.0dl/g and melting points 100-150 deg.C are coextruded and then cooled to provide an unoriented laminated sheet. This unoriented laminated sheet is stretched in the uniaxial or biaxial direction, heat-treated at the temperature higher than the melting point of propylene copolymer and lower than that of polyethylene terephthalate, then, cooled down to the room temperature. Then, the polyethylene terephthalate film is peeled from the propylene copolymer layer to obtain a very thin polyethylene terephthalate film.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for producing an ultrathin polyethylene terephthalate film having a thickness of 1 to 5 mm.

[Prior art and its drawbacks]

As a method for producing ultra-thin polyethylene terephthalate film, a method of co-extruding polyethylene terephthalate and polypropylene, laminating them, stretching this, and then peeling off the polyethylene terephthalate film was disclosed in Japanese Patent Laid-Open No. 5
7-176125.58-5226.58-13641
It is described in Publication No. 7, etc., and is well known.

However, such conventional methods have three drawbacks: frequent film tearing during stretching, large film thickness unevenness, and poor peelability when peeling the polyethylene terephthalate film from the polypropylene layer.

[Purpose of the invention]

The object of the present invention is to create an ultra-thin polyethylene terephthalate film that has less tearing during stretching, less uneven film thickness, and excellent peelability! I! J8 method Imm(rA,,L-tAlF)-FAA- [Structure of the invention] In order to achieve the above object, the present invention has the following structure, namely, polyethylene having an intrinsic viscosity of 0.55 to 0.75 dα/9. Terephthalate and extreme viscosity 1゜0~2.0dQ/Q
, a propylene copolymer with a melting point of 100 to 150°C is coextruded to form a laminated sheet, which is stretched in the -axial or biaxial direction, and then is higher than the melting point of the propylene copolymer and lower than the melting point of polyethylene terephthalate. After heat treatment at temperature, the polyethylene terephthalate film is cooled to room temperature and then peeled off from the propylene copolymer layer.
This article outlines a method for producing an ultra-thin polyethylene terephthalate film.

Polyethylene terephthalate according to the present invention means that 90 mol% or more of the molecular weight M is ethylene terephthalate 11.
1, and its limiting viscosity ffj G; &
0,55~0,75 dD,/Q, preferably 0.58~0.70(J(1/Q(Dflu).

If the intrinsic viscosity is larger or smaller than the above range, the film will have a large thickness unevenness, which will not meet the purpose of the present invention. Of course, copolymerization of known copolymerized molecular units, such as ethylene isophthalate, butylene terephthalate, ethylene adipate, ethylene rebacate, polyethylene glycol, etc., may also be used as long as the ethylene terephthalate unit does not become less than 90 mol%. It is included in the polyethylene terephthalate referred to in the invention.

Further, known additives such as organic or inorganic fine particles, pigments, plasticizers, waxes, antioxidants, ultraviolet absorbers, antistatic agents, etc. may be added to this polyethylene terephthalate depending on the purpose. . (In the following explanation, polyethylene terephthalate will be abbreviated as PET.

) Propylene copolymer is propylene 80-97 mol%
and 3 to 20 mol% of olefin other than propylene. Specific examples include propylene/ethylene copolymer, propylene/butene copolymer, propylene/hexene copolymer, propylene/ Examples include ethylene-butene terpolymers and mixtures thereof. As for the copolymerization mode, a random copolymer is preferable, but a block copolymer can also be used.
It can be used depending on the degree of pluck. In addition, even if it is a mixture of propylene copolymer and other polyolefins (e.g. polyethylene, polybutene, etc.), if the propylene copolymer accounts for 50% by weight or more, preferably 75% by weight or more of the mixture, It can be included in the scope of the propylene copolymer referred to in the present invention.

The intrinsic viscosity of the propylene copolymer used in the present invention is 1. O
~2.0dfl/gll? Preferably 1.2 to 1.8 dα
/g is essential.

If it is outside this range, the film will have poor thickness unevenness, which will not meet the purpose of the present invention.

In addition, the melting point of propylene copolymer is 100 to 150°C
, preferably 105 to 140°C, more preferably 11
The number of cores is within the range of 0 to 135°C. If it is outside this range, the frequency of film breakage during stretching increases, which is not preferable.

It is abbreviated as RPC. ) In the present invention, PET and RPC are supplied to separate extruders, melt-extruded at an extrusion temperature of 200 to 300°C, the melts are merged inside the polymer tube or the nozzle to form a layered state, and the lamination is carried out from the nozzle. Extrude as a sheet (this is called coextrusion). This laminated sheet may be two layers of PET/RPC, three layers of PET/PPC/PET, or 1) E T / P P C / P E T
/PPC/PET may have five layers.

In any case, it is desirable that a PET layer be present on at least one side of the outermost layer.

Otherwise, in the heat treatment after stretching, the film tends to become distorted, cracked, and have uneven thickness.

The coextruded molten laminated sheet is wound around a cooling drum with a surface temperature of 10 to 60°C, and cooled to 20 to 70°C to solidify it to form an unstretched laminated sheet. During this cooling and assimilation, a wire to which a direct current high voltage of 1 to 15 KV is applied is placed on the upper surface of the molten sheet, and the molten sheet is pressed against a drum by this electric charge to obtain a layered sheet. This sheet is 80
The film is heated to 130 DEG C., preferably 90 DEG to 120 DEG C., and stretched 3 to 5 times in the uniaxial direction. This stretching may be performed in two to three stages. Next, in the case of biaxial stretching, the above-mentioned uniaxially stretched film is stretched in a direction perpendicular to the front direction at a stretching speed of 1,
Stretched at 3° and 5 to 6 times at a rate of 000 to 10,000%/min. The stretching temperature in this case is preferably 5 to 20°C higher than the temperature during the previous uniaxial stretching. In addition, as another method, the above unstretched laminated sheet 1- is heated at 80 to 130°C.
Preferably, the film may be biaxially stretched by heating to 90 to 120°C and simultaneously stretching in both directions for 3 to 5 degrees. Further, the biaxially stretched film may be re-stretched by 1°1 to 2.0 times in either Ij direction.

Next, this stretched laminated film is
Heating to a temperature above the Uit point of PET and below the melting point of PET,
Heat treatment is performed for 1-20 seconds, preferably 2-10 seconds.

This heat treatment is performed by keeping the film under tension and using the area after stretching as a standard.
It is preferable to perform heat treatment while giving an area relaxation rate of ~15%, as this will improve the peelability when peeling the PET film later (Example of calculation of area relaxation rate: film surface after stretching (a100o#) However, during the heat treatment, if it undergoes slight relaxation in the -axis direction or biaxial direction and contracts, and the area after the heat treatment is 96 ffl, the area relaxation rate is 4%). If this heat treatment temperature is lower than the melting point of RPC, it is not preferable because the releasability when peeling off the PET film later becomes poor, and conversely, 1) E T
If the temperature is higher than the melting point of , the PET film will become cloudy and brittle, making it impossible to peel it off, which is not preferable.

Next, the heat-treated laminated film is slowly cooled to room temperature, typically 20 to 40°C. Cold 7JI may be performed with air or water, or may be cooled by contacting with a cooling roll. J3, the cooled film may be kept at that temperature or heated again to 50 to 90°C with a heating roll to perform corona discharge treatment on one or both sides of the film.

This treatment may make it easier to peel off the PET film later. The PET film is peeled off from the laminated film thus obtained, and the thickness is usually 0.2 to 4 μm.
nl, preferably A R9P with a J diameter of 0.2 to 2 μm
E 1 - Obtain a film. This peeling method is not particularly limited, but continuous peeling is easy if the VI layer film is nipped between a set of nip rolls and the PET film is peeled along the surface of one of the rolls. . In addition, after printing, lamination 1, ], tertin or vapor deposition is applied to the ET side of the laminated film, the PET film is peeled off. In either case, it is essential to remove static electricity on the surface of the T-fill Lx to be peeled off using a static eliminator or the like in order to facilitate peeling.

/, @A3, The present invention is characterized by the above method, but in the P)) C layer, C), 001-1
徂fij 96, llr ma L < I, L O, OO
5~0, 5'A L3-% (7) Non-Ne) "Ir
Contains lubricant] I! Shitte J3<especially one E'
[The releasability of the film can be further improved.

) 1 Sanne\°l lubricant is a liquid or molten substance that is added to PPC melt-extruded hot stones, and its addition improves the lubricity of PPC limestone. Examples include the following substances: In addition, when two or more types of these substances are contained in the film, their total (6) should just be within the above content range.

A, aliphatic hydrocarbon liquid paraffin, microcrystalline wax, natural paraffin, synthetic paraffin, polyethylene wax,
polypropylene wax etc.

B, higher fatty acid or its metal salt stearic acid, stearin ffQ/J lucium, didroxystearic acid, hydrogenated oil, sodium montanate, etc.

C1 fatty acid amide stearamide, oleic acid amide, erucic acid amide, ricinoleic acid amide, behenamide, methylene pistearamide, etc.

D. Fatty acid esters: 1-butyl stearate, methyl hydroxystearate, myricyl cerotinate, polyhydric alcohol fatty acid esters, ester waxes, fatty acid ester waxes, etc.

[, fatty alcohols lauryl alcohol, sudearyl alcohol, myrisudyl alcohol, cedyl alcohol, etc.

G, Partial ester of fatty acid and poly-IJli alcohol Glycerin fatty acid ester, Hydroxystearin M l~
Liguleride, sorbitan fatty acid gostil, etc.

1", nonionic surfactant polyoxyethylene argyl ether, polyol-1-nitheburene phenyl ether, polyoxy] dithylene j
I) 4-silamide, boriogythyethylene 1-digital acid J ster, etc.

1. Silicone oil linear methyl silicone oil, methifurnyl silicone oil,
Modified silicone oil etc.

J, fluorosurfactants such as fluoroalkylcarbonylcarboxylic acid, monoperfluoroalkyl edyl phosphate, perfluoroalkyl sulfonate, etc.

In addition, when used in combination with the above non-particulate lubricant, an average particle size of 0.0
01-2 μm inorganic fine particles, such as dry silica, wet silica, zeolite, calcium carbonate, calcium phosphate, kaolin, kaolinite, clay, talc, titanium oxide, alumina, zirconia, aluminum hydroxide, etc., as particulate lubricants, l) 0.01~ in PC film
When the content is 0.5% by weight, the effect of the non-particulate lubricant can often be enhanced synergistically.

〔Effect of the invention〕

The present invention utilizes PET and R with specific physical properties as described above.
After coextruding PC and stretching, it is heat-treated in a specific temperature range, and then the PET film is peeled off to form a polar ii9 P E
1-The method for producing the film has the following effects: a reduction in the frequency of film breakage during stretching, a reduction in film thickness unevenness, and an improvement in peelability when peeling the PFT film. It has become possible to stably manufacture . The ultrathin P E 1 thus obtained
- The film can be used for many purposes, such as base film for condenser printing, II for stencil printing, paper or typewriter ribbon.

[Measurement method J3 of physical properties and evaluation criteria] The measurement method J3 of physical properties and the evaluation criteria of each property used in the present invention are as follows.

(1) PlET (I) E 1- was dissolved in phenol with a limiting viscosity of 25° C., and the ultimate viscosity was measured using the Shin method.

(2) Intrinsic viscosity of P P C ASTM-Dl (intrinsic viscosity of 301 was used.

(3) Melting point 1) Using SC, heat the water at a rate of 20°C/min. The melting point was defined as the temperature corresponding to the top of the endothermic peak that corresponds to the solution (sample ffl: 1
01B).

In addition, fusion 1+. When two or more peaks of t appeared, the temperature at the top of the higher peak was taken as the melting point.

(4) Frequency of film breakage The frequency of film breakage was expressed as the number of times film breakage occurred during continuous biaxial stretching film formation for 8 hours. Therefore, the unit is times/8
'11. 'There is one C. '7;', this (target twice/
Unless it is 8 hours or less, it is difficult to put it into practical use.

(5) Film thickness unevenness The thickness of the heat-treated and cooled laminated film in the film width direction is continuously measured using an electronic film thickness i+ (
Film width 1m). Divide the difference between the thickness of the thickest part and the thickness of the thinnest part by the average thickness, and add 1
Multiply by 00 to obtain thickness unevenness (%). Usually, if this value is less than 10%, it is considered to be impractical.

'([3) Peelability of PET film From the obtained laminated film, l
) E-1-Continuously peel the film and evaluate the following three
! Evaluated based on standard.

``Good'': No film cut or tear, 500m
Those that were able to be peeled off continuously.

゛′酋通”: Continuous peeling is possible for about 100 to 300 meters, but
At that level, the film will break - 1b will tear.

``Poor'': Continuous peeling of only about 10 to 90 m is possible.

Of course, it can be said that if the releasability is not "good", it will be of poor practical use.

[Example a3 and Comparative Examples] Hereinafter, one embodiment of the present invention will be explained using Examples J'; J: and Comparative Examples.

Example 1 The following 2
ii I did.

PET: Homopolymer of poly'nitylene terephthalate-1-. Intrinsic viscosity 0.62 dfl/g, fMi point 259
"C.

P P C: 'L-ethylene-containing propylene-ethylene random co-base with 6% by weight. Intrinsic viscosity 1, 656
71/<7. It contains 0.3 x Φ% of H11 point 120'' cocolic acid nomide and 0.3% of calcium carbonate with an average particle size of 0.9 μm.

These two types of raw materials are each fed to separate extruders to produce PET
280'C
/ P P C (2 layers) was wound around a cooling drum at 30°C, and cooled and solidified while applying a DC high voltage of 8 KV to form two-layer laminated sheets 1 to 1. This sheet was After heating to 90°C, stretching 3.1B in the longitudinal direction,
Immediately cooled down to 30℃ for 7Jl.

Next, it was heated to 100°C again and stretched at a speed of 2 in the width direction.
, stretched 5.0 times at 500%/min, then lowered the temperature to 2
The temperature was raised to 15°C and heat treated for 5 seconds. J3 was located within this heat treatment section, and relaxation treatment was performed with an area relaxation rate of 5%. This film was slowly cooled to room temperature and wound up while removing static electricity using a static eliminator. The thus obtained laminated film had a PET layer of 1.0 μm and a PP0 layer of 10 μm.

The frequency of film tearing when this film was continuously formed was O
At 8 o'clock, the thickness unevenness of the film was 5%, which was good. Next, from this laminated film, P] Sancho Fill 11 was applied between the rows, and the IC was able to be peeled off continuously over 500+U, and the peelability (very good) was obtained. Comparative Example 1 Example 1 l) Instead of PC, the intrinsic viscosity is 2.3d.
σ/g l) l−' C was used (other characteristics of RPC are the same as in Example 1). When a film was formed in the same manner as in Example 1, the thickness unevenness of the film was very poor at 25%.

Comparative Example 2 On the contrary, Comparative Example 1 etc. had P l) with an intrinsic viscosity of 0.8 dα/q.
When a film was formed using C in the same manner as in Comparative Example 1 (Example 1), the film thickness unevenness was 32%.
l 7i', but it becomes inferior to Phil l\\
The frequency of breakage increased to 6 times/8 hours.

Comparative Example 3 A film was formed in the same manner as in Example 1 except that the 1-tyrene content of l' I) C of Example 1911 was changed and RPC with a melting point of 155°C and a melting point of 95°C was used. , any l) l) Even if C is used, film tearing Mi +
It was worn over 20 times in the summer for 8 hours or more, and was extremely prone to tearing, making it impractical.

Comparative Example 4 Instead of PET in Example 1, intrinsic viscosities of 0.50 and 0.80d0. /g of PET and the other conditions were the same as in Example 1.
Even if T was used, the thickness unevenness of the film was extremely poor, exceeding 20%.

Comparative Example 5 d3 in Example 1, heat treatment temperature after stretching was 110°C
I tried forming a film with the other conditions unchanged. When the peelability of the obtained laminated film was evaluated, it was found to be "fair" and somewhat lacking in practicality.

Patent applicant Higashi Shikikai Co., Ltd.

Claims (1)

[Claims] Polyethylene terephthalate with an intrinsic viscosity of 0.55 to 0.75 dα/g and a propylene copolymer with an intrinsic viscosity of 1.0 to 2° Odα/g and a melting point of 100 to 150°C are coextruded to form a laminated sheet, which is uniaxially Alternatively, the polyethylene terephthalate film is stretched in the two-wheel direction, then heat treated at a temperature higher than the melting point J of the propylene copolymer and lower than the melting point of polyethylene terephthalate, cooled to room temperature, and then the polyethylene terephthalate film is separated from the propylene copolymer layer. A method for producing an ultra-thin polyethylene terephthalate film that can be peeled off.