JP2550745B2 - Polyester resin film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a film, particularly a polyester resin film.

[Conventional technology]

A polyester resin film, particularly a biaxially stretched polyester resin film typified by a polyethylene terephthalate resin film has excellent electrical properties, mechanical properties, thermal properties, processability, and chemical resistance.
It is used as a base film in a wide range of fields such as magnetic tapes, capacitors, packaging materials, photolithography, and electrical insulation materials.

Such a polyester resin film is required to have good transparency and slipperiness in addition to the above-mentioned characteristics.
For example, Japanese Unexamined Patent Publication (Kokai) No. 62-70064 discloses a multilayer polyester resin film as a polyester resin film excellent in transparency and slipperiness. In this polyester-based resin film, a polyester-based resin film satisfying specific physical properties is laminated in multiple layers, and by incorporating fine particles such as organic particles into the polyester-based resin film on the surface side, transparency and slipperiness are improved. Are realized at the same time.

[Problems to be Solved by the Invention]

The conventional polyester-based resin film has improved slipperiness as compared with the polyester-based resin film containing no fine particles, but its degree is not sufficient, and thus the handling property is poor. Further, since the film is likely to break during film formation, continuous film formation for a long time is difficult. In addition, scratches are likely to occur due to the added fine particles.

An object of the present invention is to provide a polyester resin film which has good transparency and slipperiness and is less likely to be broken during film formation.

[Means for solving the problem]

The polyester resin film of the present invention has an intrinsic viscosity A
And a coating layer having a thickness of T μm, which is laminated on the base material layer and is made of a polyester resin having an intrinsic viscosity B and containing organic particles having an average particle diameter of dμm. The polyester resin film of the present invention satisfies the following conditions.

0.5 ≧ BA ≧ 0.02 25 ≧ T / d ≧ 1.5 In the present invention, the difference (ba) between the plane orientation coefficient a of the base material layer and the plane orientation coefficient b of the film is, for example, 1 × 10 ⁻ It is set to ³ or more. The average particle diameter d of the organic particles is set to 0.2 to 1.0 μm, for example. The amount of organic particles added to the polyester resin having an intrinsic viscosity B is set to, for example, 1% by weight or less.

*********** Polyester Resin The polyester resin used in the present invention is a polymer containing an ester group obtained by condensation polymerization of a dicarboxylic acid and a diol. Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, adipic acid, sebacic acid, 2,6-naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, bis-α, β (2-chlorophenoxy)
There may be mentioned aliphatic and aromatic dicarboxylic acids such as ethane-4,4'-dicarboxylic acid, succinic acid and oxalic acid. Examples of the diol include ethylene glycol, 1,
4-butanediol, diethylene glycol, polyethylene glycol, neopentyl glycol, cyclohexanedimethanol, polyethylene glycol and the like can be mentioned. Two or more kinds of each of the dicarboxylic acid and the diol may be used. The intrinsic viscosity of such a polyester resin is preferably 0.4 to 2.0 as measured in 25 ° C. o-chlorophenol, and more preferably 0.
5 to 1.0 is preferable.

In the polyester resin used in the present invention, other monomers or polymers may be copolymerized within 10 mol% in addition to the above dicarboxylic acid and diol. Also,
Two or more types of polyester resins may be melt mixed and used.

Incidentally, particularly preferable polyester resins used in the present invention are polyethylene terephthalate, polyethylene-2,6-naphthalate, and polyethylene-α, β.
Bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate.

The polyester resin used in the present invention contains other types of polymers, ultraviolet absorbers, lubricants, pigments, antioxidants, heat stabilizers, antistatic agents, etc. within a range that does not impair the object of the present invention. May be.

Base Material Layer The base material layer forming the polyester resin film of the present invention is formed using the above polyester resin. The thickness of the base material layer is preferably 0.5 to 800 μm, more preferably 2 to 500 μm.

Coating Layer The coating layer constituting the polyester resin film of the present invention is laminated on one side or both sides of the above-mentioned base material layer.
This coating layer is made of the above-mentioned polyester resin as in the base material layer. The thickness T of the coating layer is 0.01-25
μm is desirable, and 0.3 to 3.0 μm is desirable.

Intrinsic viscosity B of polyester resin used for coating layer
Is set to be larger than the intrinsic viscosity A of the polyester resin used for the base material layer. Thus, by using a polyester resin having a higher intrinsic viscosity than the base material layer on the coating layer side, it is possible to reduce breakage during film formation. Further, when the polyester-based resin film is stretched, the height of the protrusions formed on the coating layer side can be increased by the organic particles described later, which makes it possible to impart better slipperiness to the film. become.

In the present invention, the difference between the intrinsic viscosity A and the intrinsic viscosity B (B
-A) is set in the range of 0.02 to 0.5. If the difference in intrinsic viscosity is less than 0.02, the height of the protrusion cannot be sufficiently increased during stretching of the film, and the slipperiness of the film is reduced. On the other hand, if it exceeds 0.5, the height of the protrusions becomes too high when the film is stretched,
Scratches are likely to occur during film formation.

The polyester resin forming the coating layer contains organic particles. Protrusions formed by the organic particles are formed in the coating layer, and thus the polyester resin film is provided with slipperiness. As the organic particles, fine particles made of an organic polymer compound are used. Examples of the organic polymer compound include divinylbenzene-styrene cross-linked copolymer, polyimide, silicone resin and the like. The molecular weight of these polymer compounds is not particularly limited, but is preferably 5,000 or more, more preferably 10,000 or more.

The surface of the above-mentioned organic particles may be either active or inactive. The organic particles are 10% in the heating weight loss curve.
The temperature at the time of weight reduction is preferably 350 ° C (preferably 370 ° C, more preferably 400 ° C) to 600 ° C.

The organic particles can be obtained, for example, by crushing the above resin. Further, particles obtained by emulsion polymerization may be used. In this case, the size of the particles is relatively uniform, which is preferable.

The sphericity (major axis / minor axis) of the organic particles is preferably 1.2 or less, more preferably 1.1 or less from the viewpoint of quality stability. Further, as the organic particles, those having an average particle diameter d in a ratio T / d with the thickness T of the above-mentioned coating layer in the range of 1.5 or more and 25 or less are used. When the T / d value is less than 1.5, unevenness in protrusions is likely to occur on the coating layer. On the other hand, when it exceeds 25, the transparency of the coating layer is lowered. The average particle diameter d of the organic particles is preferably 0.2 to 1.0 μm, more preferably 0.25 to 0.7 μm. When d is less than 0.2 μm, the slipperiness of the polyester resin film may not be sufficient. On the other hand, when d exceeds 1.0 μm, scratches are likely to occur during film formation. In addition,
The average particle diameter d of the organic particles can be obtained by the weight average method using the sedimentation method.

The amount of the organic particles added is preferably 1% by weight or less of the polyester resin forming the coating layer. If the amount added exceeds 1% by weight, the transparency of the film may be reduced.

If necessary, inorganic particles may be added to the polyester-based resin within a range not exceeding the addition amount of the organic particles.

In the present invention, the plane orientation coefficient b of the coating layer is preferably set larger than the plane orientation coefficient a of the base material layer. According to this, the stretchability of the film on the side of the coating layer at the time of stretching of the film is good, and the height of the projections by the organic particles in the coating layer can be increased to further improve the slipperiness. In addition, breakage during film formation becomes more difficult to occur.

In this case, the difference (ba) between the plane orientation coefficient b and the plane orientation coefficient a is set to 1 × 10 ⁻³ or more. If the difference in plane orientation coefficient is less than 1 × 10 ⁻³ , the film forming process becomes unstable. The surface orientation coefficient (b) of the coating layer was determined by using methylene iodide as the mount solution and using an Atsube refractometer to measure the refractive index n _{MD in} the length direction (MD direction) and the refractive index in the width direction (TD direction). The rate n _TD and can be measured and found by | n _MD −n _TD |.
On the other hand, the surface orientation coefficient of the base material layer can be measured as follows. First, the birefringence (R
a) is measured. Moreover, the thickness (T + Tb) of the composite film is measured using a dial gage, and the thickness (Tb) of the base material layer is further measured from a cross-sectional photograph of the composite film. Then, the plane orientation coefficient (a) can be known from the obtained data by the following formula.

Method for Manufacturing Polyester Resin Film First, a polyester resin A for a base material layer and a polyester resin B for a coating layer, which satisfy the above physical properties, are prepared. It should be noted that the polyester resin B for the film layer is preliminarily added with organic particles by a method such as a dry blending method or a polymerization addition method.

Next, the polyester resins A and B are dried under predetermined conditions and then fed to separate extruders. Then, both resins are laminated by the co-extrusion method, cooled and solidified on the casting drum to manufacture a polyester resin film in which the above polyester resins A and B are laminated. The polyester resins A and B may be laminated by a method other than the co-extrusion method. For example, they may be laminated in a short tube portion or a feed block before the mouthpiece of the extruder. Alternatively, they may be laminated inside the die.

Next, the obtained polyester resin film is stretched. The stretching treatment may be performed uniaxially, biaxially or more. The stretching conditions are not particularly limited. However, it is first stretched at 75 to 130 ° C in the uniaxial direction (usually the longitudinal direction) by 2.0 to 9.0 times, and then at 80 to 160 ° C in the perpendicular direction (usually in the transverse direction) at 2.0 to 9.0 times, and if necessary, 0
It is desirable to apply heat treatment while relaxing ~ 15%. Moreover, you may re-stretch 1.05-1.8 times as needed. Alternatively, after stretching in the uniaxial direction, various coating agents may be applied to the film, dried, and then stretched in the perpendicular direction.

The plane orientation coefficient of the base material layer and the coating layer can be set within the above range by setting the atmosphere during stretching of the film and the roll temperature for stretching to be lower than the preheating temperature of the film. For example, when the film is rapidly placed in a low-temperature atmosphere before stretching the film, the temperature of only the film layer side is lowered, so that the surface orientation coefficient of the film layer becomes higher than that of the substrate layer. As described above, by adjusting the temperature condition during the stretching of the film, it is possible to provide a difference in the plane orientation coefficient between the base material layer and the coating layer.

Utilization of Polyester Resin Film The polyester resin film of the present invention is used, for example, as a packaging material for foods and pharmaceuticals, a transfer film, a projector film, a magnetic tape, an electric insulating material and the like. In particular, since the polyester resin film of the present invention has good transparency, it is used as a film required to have transparency like a film for a projector.

〔The invention's effect〕

The polyester resin film of the present invention includes the above-mentioned base material layer and coating layer. Therefore, according to the present invention, it is possible to realize a polyester resin film which has good slipperiness and transparency and is less likely to be broken or scratched during film formation.

〔Example〕

Examples 1 to 11 and Comparative Examples 2 to 9 A homopolymer of polyethylene terephthalate for a base layer having an intrinsic viscosity A shown in the table and a polyethylene terephthalate having an intrinsic viscosity B to which styrene-divinylbenzene copolymer particles were added at the time of polymerization. A homopolymer was prepared. It was then dried under reduced pressure for 4 hours each polymer chips 5mmH _g 160 ℃. The chips are supplied to separate extruders at 285 ° C, and the films from each extruder are laminated by the coextrusion method, cooled on a casting drum at 40 ° C, and solidified to form a base layer and a coating layer. The following polyester resin film was produced.

Next, the obtained polyester resin film was preheated at 93 ° C. and then stretched 3.3 times in the longitudinal direction using a stretching roll at 88 ° C. Subsequently, the polyester resin film stretched in the machine direction was preheated to 115 ° C., and this was stretched 3.5 times in the transverse direction in an atmosphere of 109 ° C. And while giving 6% relaxation 2
Heat treatment was performed at 25 ° C. to obtain a biaxially stretched polyester resin film.

The obtained biaxially stretched polyester resin film was examined for slipperiness, transparency, surface gloss and breakage during film formation.

Comparative Example 1 A polyethylene terephthalate homopolymer containing styrene-divinylbenzene copolymer particles and having an intrinsic viscosity of 0.80 was prepared and dried under the same conditions as in Example. Then, this polymer chip was supplied to an extruder to produce a monoaxial biaxially stretched polyester resin film under the same conditions as in the examples.

The same test as in the example was conducted on the obtained biaxially stretched polyester resin film.

Test Method Breakage The number of breakages of the film that occurred during continuous film formation for 24 hours was measured.

Sliding property was evaluated by measuring the static friction coefficient and the dynamic friction coefficient based on ASTM-D-1894.

Transparency Measured according to ASTM-D-1003.

Surface gloss A vacuum deposition machine is used to form a 250Å-thick aluminum vapor deposition film on the base layer side of a biaxially stretched polyester resin film, and the surface gloss is visually compared with Lumirror # 50T60 (trade name of Toray Industries, Inc.). It was judged by. The evaluation criteria are as follows.

○: Gloss equivalent to # 50T60.

X: Inferior to # 50T60.

Claims (4)

(57) [Claims] 1. A substrate layer made of a polyester resin having an intrinsic viscosity A, and a thickness Tμ made of a polyester resin having an intrinsic viscosity B, which is laminated on the substrate layer and contains organic particles having an average particle diameter dμm.
A polyester resin film having a coating layer of m and satisfying the following conditions: 0.5 ≧ BA ≧ 0.02 25 ≧ T / d ≧ 1.5. 2. The polyester according to claim 1, wherein the difference (ba) between the plane orientation coefficient a of the base material layer and the plane orientation coefficient b of the coating layer is 1 × 10 ⁻³ or more. Resin film. 3. The average particle diameter d of the organic particles is 0.2 to 1.0 μm.
The polyester resin film according to claim 1, wherein the polyester resin film is m. 4. The polyester resin film according to claim 1, wherein the amount of the organic particles added to the polyester resin having the intrinsic viscosity B is 1% by weight or less.