JP3265798B2 - Polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film having excellent abrasion resistance and antistatic performance.

[0002]

2. Description of the Related Art In general, polyester, for example, polyethylene terephthalate has excellent mechanical properties and chemical properties, and is widely used as molded articles such as films and fibers. When processed into a polyester molded product and used, its slipperiness and abrasion resistance greatly affect the workability in the manufacturing process and the processing process in various applications.
For example, when used as a base film for a magnetic tape, if these properties are insufficient, the friction between the coating roll and the film increases in the magnetic tape manufacturing process, causing wrinkles and scratches on the film. Further, abrasion powder of the film is liable to be generated, and coating omission occurs in the step of applying the magnetic layer, which may cause dropout of magnetic recording. Further, even when used as a magnetic tape, abrasion powder is generated due to contact running with various guide pins in the VTR deck at the time of recording and reproduction, and dropout is caused.

Hitherto, as a method for improving the slipperiness of a film, many proposals have been made to incorporate inorganic particles such as titanium dioxide, calcium carbonate and silicon dioxide into polyester. However, because these particles are generally hard and have low affinity for polyester, for example,
The film easily falls off due to an external force applied to the contact running during the film manufacturing process or recording / reproducing, and the slipperiness and the above-mentioned dropout are liable to occur. In order to solve such disadvantages of the inorganic particles, recently, Japanese Patent Publication No. 63-45409, Japanese Patent Application Laid-Open No. 59-217755, and Japanese Patent Application Laid-Open No.
No. 9 proposes particles made of a crosslinked organic polymer.

On the other hand, the polyester of the matrix has a disadvantage that it is easily charged. In particular, when the above-mentioned crosslinked polymer particles are used, the abrasion resistance is improved, but in some cases, the molded article is more easily charged than inorganic particles. There was a tendency. If the chargeability is high, for example, when processed into a film,
Problems such as winding around a roll in the film forming process, contamination of the film surface due to suction of dust and dust, and poor printing occur. For this reason, there has been a need for a polyester composition having excellent antistatic properties as well as abrasion resistance.

[0005]

OBJECTS OF THE INVENTION It is an object of the present invention is to overcome the drawbacks of the prior art, provides child a polyester film excellent in abrasion resistance and antistatic properties
And there .

[0006]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
“The crosslinked polymer particles having a thermal decomposition temperature of 350 ° C. or more and the metal sulfonic acid salt represented by the formula (1) are 0.1 to 10%.
A polyester film , characterized in that the polyester film further contains inorganic particles . R (X) _n SO ₃ M (1) (where R represents an alkyl group having 5 to 30 carbon atoms, X represents an aromatic group, n represents 0 to 1, and M represents an alkali metal element) ”. .

The polyester in the present invention includes aromatic dicarboxylic acids such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid and isophthalic acid as acid components, and ethylene glycol, butanediol and cyclohexanedimethanol as glycol components. It is an aromatic polyester comprising glycol.
Specific examples include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and the like. It may be a copolymerized polyester in which two or more of the above-mentioned acid component and diol component are used in combination.

[0008] The polyester of the present invention can be produced by a conventionally known method.

For example, polyethylene terephthalate (PE
In the case of T), terephthalic acid (TPA) and ethylene glycol (EG) are directly esterified, or dimethyl terephthalate (DMT) and EG are subjected to a transesterification reaction to obtain bishydroxyethyl terephthalate and its low polymer (BHT). And then heating under reduced pressure to remove EG. At this time, additives such as a catalyst can be optionally used as needed.

The polyester of the present invention must contain 0.1 to 10% by weight of a metal sulfonic acid salt represented by the following formula. R (X) _n SO ₃ M (where, R represents an alkyl group having 5 to 30 carbon atoms, X represents an aromatic group, n represents 0 to 1, and M represents an alkali metal element). is, R-X-SO ₃ M
An alkali metal salt of an aromatic sulfonic acid represented by
Although it is an aliphatic sulfonic acid alkali metal salt represented by SO ₃ M, the number of carbon atoms in the alkyl group needs to be 5 to 30. When the number of carbon atoms is in the range of 5 to 30, the metal sulfonic acid salt has excellent dispersibility in the polyester and exhibits a good antistatic effect.

Examples of the sulfonic acid metal salt forming R (X) _n SO ₃ M include octylbenzene sulfonic acid,
Examples include, but are not limited to, dodecylbenzenesulfonic acid, octadecylbenzenesulfonic acid, undecylsulfonic acid, dodecylsulfonic acid, octadecylsulfonic acid, and the like. The type of M is a lithium salt,
Examples thereof include a sodium salt and a potassium salt, and a lithium salt can be preferably used in terms of antistatic performance and abrasion resistance. The content of the sulfonic acid metal salt compound is 0.1 to 10% by weight, preferably 0.2 to 5% by weight, particularly preferably 0.3 to 3% by weight, based on the polyester. When the content is less than 0.1% by weight, the antistatic performance is insufficient. On the other hand, when the content exceeds 10% by weight, the antistatic effect no longer reaches saturation, but on the contrary, gel-like foreign matter is easily generated. And, furthermore, the mechanical properties deteriorate, which is not preferable.

The average molecular weight of the polyoxyalkylene glycol in the present invention is preferably from 1,000 to 200,000. A more preferred average molecular weight is 5,000
0-100,000, particularly preferred average molecular weight is 8.0
00 to 50,000. By setting the average molecular weight of the polyoxyalkylene glycol in the above range, the effect of improving the antistatic property can be sufficiently obtained.

The content of the polyoxyalkylene glycol in the present invention is preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight. When the content is within the range of the present invention, the improvement in antistatic properties is remarkable.

The polyoxyalkylene glycol in the present invention may be copolymerized with a polyester,
You don't have to.

The crosslinked polymer particles in the present invention include:
Copolymers of a monovinyl compound (A) having only one aliphatic unsaturated bond in the molecule and a compound (B) having two or more aliphatic unsaturated bonds in the molecule as a crosslinking component are exemplified. Can be

Examples of the compound (A) in the above copolymer include aromatic monovinyl compounds such as styrene, α-methylstyrene, fluorostyrene, vinylpyrine and ethylvinylbenzene, and vinyl cyanide compounds such as acrylonitrile and methacrylonitrile. Acrylic acid such as, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate, dodecyl acrylate, hexadecyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, N, N'-dimethylaminoethyl acrylate Ester monomers, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate,
Butyl methacrylate, sec-butyl methacrylate, allyl methacrylate, phenyl methacrylate,
Mono- or dicarboxylic acids such as methacrylic acid esters such as benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, N, N'-dimethylaminoethyl methacrylate, acrylic acid, methacrylic acid, maleic acid, and itaconic acid; Acid anhydrides of dicarboxylic acids,
Amide monomers such as acrylamide and methacrylamide can be used. As the compound (A), styrene, ethylvinylbenzene, and methyl methacrylate are particularly preferably used.

Examples of the compound (B) include a divinylbenzene compound, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate,
Or ethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol diacrylate,
Polyhydric acrylates and methacrylates such as 1,3-butylene glycol dimethacrylate, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate are exemplified. Among the compounds (B), divinylbenzene, ethylene glycol dimethacrylate or trimethylolpropane trimethacrylate is particularly preferably used.

Preferred examples of the composition of the crosslinked polymer particles of the present invention include divinylbenzene polymer, ethylvinylbenzenedivinylbenzene copolymer, styrenedivinylbenzene copolymer, styrene-ethylvinylbenzene-divinylbenzene. Crosslinked polymer particles such as a copolymer, an ethylene glycol dimethacrylate polymer, a styrene-ethylene glycol dimethacrylate copolymer, and a methyl methacrylate-divinylbenzene copolymer are exemplified. Further, a system of three or more components may be used.

The composition of the crosslinked polymer particles in the present invention is not particularly limited. However, even if the particles having the above-mentioned various compositions do not have a specific heat resistance, the object of the present invention can be attained. The effect cannot be obtained.

Regarding the heat resistance of the crosslinked polymer particles in the present invention, the thermal decomposition temperature by a thermobalance (10 ° C.
(% Weight loss temperature) is 350 ° C. or more in order to reduce the particle aggregation at the time of producing the polyester composition, at the time of melt molding, or at the time of recovery and reuse. It is more preferably at least 360 ° C, particularly preferably at least 370 ° C.

The heat resistance of such crosslinked polymer particles largely depends on the degree of crosslinking. That is, when the degree of crosslinking defined by the formula (2) is at least 10% by weight, more preferably at least 30% by weight, and particularly preferably at least 50% by weight, based on all the organic components constituting the particles, the heat resistance is good. Becomes Degree of crosslinking = (weight of crosslinking component in raw material monomer) / (total weight of raw material monomer) × 100 (%) (2)

The average particle size of the crosslinked polymer particles of the present invention is preferably from 0.01 to 3 μm, more preferably from 0.02 to
１1 μm.

The content of the crosslinked polymer particles in the polyester composition of the present invention is preferably from 0.005% by weight to 5% by weight. If the amount is less than 0.005% by weight, the lubricity becomes insufficient when formed into a film or the like. If the amount exceeds 5% by weight, aggregation of particles tends to occur, and coarse projections are formed on the film surface, which is not preferable.

The addition method and timing of adding the crosslinked polymer particles of the present invention to the polyester can be determined by a conventionally known method, for example, a method of adding a powder or a glycol slurry to a polyester reaction system, or a method of adding a powder. It is possible to adopt a method of kneading the polyester in the form of a body or a slurry using a low boiling point solvent. In particular, a method in which the particles are kneaded into polyester in the form of water and / or an organic compound slurry having a boiling point of 200 ° C. or lower is preferable because the dispersibility of the particles becomes good. In this case, it is more preferable to use a vent-type molding machine for deaeration.

Water and / or boiling point 2 of the crosslinked polymer particles
The concentration of the organic compound slurry at 00 ° C or lower is not particularly limited, but the amount of water and / or the organic compound having a boiling point of 200 ° C or lower based on the polymer is preferably 2% by weight or more and 30% by weight or less for good dispersibility in the polymer. It is also preferable because the intrinsic viscosity of the polymer does not decrease. More preferably, the content is 2% by weight or more and 20% by weight or less. In addition, the slurry of the crosslinked polymer particles includes anionic surfactants such as sodium dodecylbenzenesulfonate and sodium lauryl sulfate, nonionic surfactants such as polyoxyethylene nonylphenyl ether and polyethylene glycol monostearate, and polyvinylpyrrolidone. Addition of a protective agent such as polyvinyl alcohol, carboxymethyl cellulose and the like is preferable because the particle dispersibility becomes better. The amount of the protective agent with respect to the particles is preferably 0.01 to 10% by weight, more preferably 0.1 to 5% by weight.

In addition to the crosslinked polymer particles of the present invention, inorganic particles such as silicon oxide, titanium oxide, aluminum oxide, calcium carbonate, and zirconium oxide, or alkali metals and alkaline earths, as long as the object of the present invention is not impaired. Particles precipitated in a polyester polymerization reaction system containing at least one kind of metal and phosphorus as a constituent component, that is, particles such as internal particles may be contained.

As a method for producing a composition containing the inorganic particles or the internal particles and the crosslinked polymer particles of the present invention, for example, a method of adding both of them to a polyester reaction system may be used, or a method of separately adding the two to a polymer may be used. A method may be adopted in which the blended master chips are blended again and melt-kneaded.

When the polyester composition of the present invention is used as a film, it can be applied to either a single layer or a laminated film. However, from the viewpoint of surface flatness, at least one film composed of the polyester composition of the present invention is used. Films laminated to layers are preferred.

It is more preferable that the laminated film composed of the polyester composition of the present invention has a structure of three or more layers from the viewpoint of abrasion resistance. The film composed of the polyester composition of the present invention has a three-layer structure. It is preferably at least one outermost layer of the laminated film. When particles other than the crosslinked polymer particles of the present invention are contained, the combined particles may be contained in the same layer as the crosslinked polymer particles of the present invention.

It is particularly preferable from the viewpoint of abrasion resistance that the layer containing the crosslinked polymer particles of the present invention is contained in the outermost layer, and the relationship between the thickness t of the film layer and the particle size d of the particles. But 0.2d ≦ t ≦ 10d, preferably 0.5d ≦ t
≦ 5d, more preferably 0.5d ≦ t ≦ 3d, and the thickness of the outermost layer is 0.005 to 1 μm, preferably 0.01 to 0.5 μm, more preferably 0.02
０．３0.3 μm. Further, from the viewpoint of abrasion resistance, it is preferable that the number of protrusions on at least one side of the polyester film is 2 × 10 ^{3 to} 5 × 10 ⁵ / mm ² . The number of protrusions on at least one side is preferably 3 ×
10 ³ -4 × 10 ⁵ / mm ² , more preferably 5 × 1
0 ^{3 to} 3 × 10 ⁵ pieces / mm ² .

Next, a method for producing the above film will be described. After drying the crosslinked polymer particles in the present invention and the pellets containing a predetermined amount of other particles as necessary, the dried pellets are supplied to a known melt extruder, extruded into a sheet shape from a slit die, and cooled on a casting roll. It is solidified to make an unstretched film. In the case of a laminated film, 2
Alternatively, the molten polyester is laminated using three extruders, two or three layers of manifolds or merging blocks. In this case, a method of installing a static mixer and a gear pump in the flow path containing the aggregated particles may be used.

Next, the unstretched film is biaxially stretched and biaxially oriented. As the stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. However, using a sequential biaxial stretching method in which stretching in the longitudinal direction and then in the width direction is performed first, the stretching in the longitudinal direction is divided into three or more stages, the longitudinal stretching temperature is 80 ° C to 150 ° C, and the total longitudinal stretching ratio is 3. 0-5.5
And the longitudinal stretching speed is preferably in the range of 5,000 to 50,000% / min. As the stretching method in the width direction, a method using a stenter is preferable. The stretching temperature is 80 to 160 ° C., the stretching ratio in the width direction is larger than the longitudinal ratio, 3.5 to 6.5 times, and the stretching speed in the width direction is 1000 to 20,000%. / Min is preferred.

Next, the stretched film is heat-treated. The heat treatment temperature in this case is 170 to 200 ° C., particularly 170 to 1
The time at 90 ° C. is preferably in the range of 0.5 to 60 seconds.

[0034]

The present invention will be described in more detail with reference to the following examples. In addition, the physical property in an Example was measured as follows.

(1) Average Particle Diameter of Particles The particles are mixed with polyester, and the cross section of the film is adjusted to 0.
After cutting into an ultra-thin section having a thickness of 1 μm, the section was observed with a transmission electron microscope at a magnification of 20,000 or more, and evaluated by an area average diameter (μm) of 1,000 particles.

(2) Surface Roughness of Film Using a Surfcom surface roughness meter according to JIS B-0601, needle diameter 2 μm, load 70 mg, measurement standard length 0.25 m
The center line average roughness (Ra) was measured under the conditions of m and cutoff 0.08 mm.

(3) Lamination Thickness of Laminated Film Using a secondary ion mass spectrometer (SIMS), the element and polyester originating from the particles having the highest concentration among the particles in the film having a depth of 3000 nm from the surface layer are determined. The concentration ratio of the carbon element (M ⁺ / C ⁻ ) is defined as the particle concentration, and analysis in the thickness direction from the surface to a depth of 3000 nm is performed. In the surface layer, the particle concentration is low due to the interface of the surface, and the particle concentration increases as the distance from the surface increases. In the case of the film of the present invention, the particle concentration that has once reached the maximum value starts to decrease again. Based on this concentration distribution curve, the depth at which the surface layer particle concentration is の of the maximum value (this depth is deeper than the depth at which the maximum value is obtained) was determined, and this was defined as the lamination thickness. The conditions are as follows.

Measurement device Secondary ion analyzer (SIMS) Germany, ATOMIKA
A-DIDA 3000 Measurement conditions Primary ion species O ₂ ⁺ Primary ion acceleration voltage 12 kV Primary ion current 200 nA Raster area 400 μm □ Analysis area Gate 30% Measurement vacuum degree 6.0 × 10 ⁻⁹ Torr E-GUN 0. 5 kV-3.0 A When the particles most contained in the range from the surface layer to the depth of 3000 nm are organic polymer particles, it is difficult to measure by SIMS. Therefore, XPS (X
Depth profile similar to the above may be measured by X-ray photoelectron spectroscopy), IR (infrared spectroscopy), etc. to determine the lamination thickness, or the particle concentration change state and polymer difference by cross-sectional observation using an electron microscope or the like. The interface can be recognized from the difference in contrast caused by the above and the lamination thickness can be determined. Further, after the laminated polymer is peeled off, the laminated thickness can be determined using a thin film step measuring device.

(4) Abrasion resistance A tape slit with a film width of 1/2 inch is run on guide pins (surface roughness: 100 nm in Ra) using a tape running tester (running). Speed 10
00m / min, number of runs 15 passes, winding angle: 60 °,
Running tension: 60 g). At this time, the scratches in the film were observed with a microscope. The number of scratches having a width of 2.5 μm or more per tape width was less than 2 grades A, 2 or more and less than 3 grades B, 3 grades or more.
Less than 0 pieces were classified as C class, and 10 pieces or more were classified as D class. Class B or higher was accepted.

(5) Antistatic Property Evaluated as surface resistivity. MMA manufactured by Kawaguchi Electric Works
The film was kept at room temperature 20
The measurement was performed after leaving the apparatus for 6 hours at 65 ° C. and a humidity of 65%. 1 × 10 ¹¹ Ω / □ or less was regarded as acceptable.

(6) Thermal Decomposition Temperature of Particles A 10% weight loss temperature was determined as the thermal decomposition temperature of the crosslinked polymer particles in the present invention using a thermobalance in a nitrogen stream at a heating rate of 10 ° C./min.

[0042] Comparative Example 1 Specific polyethylene terephthalate chips viscosity 0.660 using a vent type twin-screw extruder the polymer chips melted, ethylvinylbenzene / divinylbenzene thermal decomposition temperature of 355 ° C. here A 20% by weight aqueous slurry of copolymer particles was added to obtain polyethylene terephthalate (I) having a particle concentration of 0.5% by weight. During kneading, the vent port was maintained at a vacuum of 10 Torr, and the resin temperature was set to 280 ° C.

On the other hand, 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, 0.05 parts by weight of magnesium acetate as a transesterification catalyst, 0.04 parts by weight of antimony trioxide as a polymerization catalyst, and 0 parts by weight of trimethyl phosphate as a heat stabilizer. 0.03 parts by weight,
Polyethylene terephthalate (II) having an intrinsic viscosity of 0.650 was obtained by an ordinary method.

Further, polyethylene terephthalate (I
After completion of the polycondensation reaction of I), 15% by weight of lithium dodecylsulfonate is added as a metal salt compound of sulfonic acid,
After kneading for 30 minutes, the pressure inside the system is reduced again, and the polycondensation reaction is continued for 30 minutes.
Continuously, polyethylene terephthalate (III) was obtained.

The chip blend (IV) of (II), (I) and (III) was dried under reduced pressure (5 Torr) at 180 ° C. for 7 hours at 180 ° C., and then extruder 1,
The polymer (II) and the polymer (IV) were supplied to the extruder 2, respectively, and were melted at 285 ° C and 280 ° C. After high-precision filtration of these polymers, three layers were laminated at a rectangular junction (lamination structure: polymer (IV) / polymer (II) / polymer (IV)).

This was wound around a casting drum having a surface temperature of 25 ° C. by an electrostatic application casting method, and cooled and solidified to produce an unstretched film. At this time, the ratio of die slit gap / unstretched film thickness was set to 10. Further, the discharge amount of each extruder was adjusted to adjust the total thickness and the thickness of the thermoplastic resin P layer.

This unstretched film was stretched 3.5 times in the longitudinal direction at a temperature of 85 ° C. This stretching was performed in four steps with a difference in roll peripheral speed between two sets. This uniaxially stretched film is stretched 5.5 times in the width direction at 95 ° C. at a stretching speed of 2000% / min using a stenter, and heat-treated at 190 ° C. for 3 seconds under a constant length to obtain a biaxial film having a total thickness of 15 μm. An oriented laminated film was obtained. The average particle diameter of the particles measured using a section of the obtained film was 0.1. It was 5 μm. Characteristics of the film Ru der as shown in Table 1.

Examples 1 to 2 and Comparative Examples 2 to 4 In the same manner as in Comparative Example 1, the polymer composition, the composition of the inert particles, the average particle diameter, the amount added, and the types and particle diameters of the particles other than the particles, A film in which the amount added was changed was obtained. The thickness of the laminate was changed, and a single-layer film was prepared. As shown in Table 1, the film using the polyester composition in the range specified in the present invention had good abrasion resistance and antistatic properties, but those not so were insufficient.

[0049]

[0050]

[Table 1]

The polyester film of the present invention contains crosslinked polymer particles having a high thermal decomposition temperature and a specific metal salt of sulfonic acid , and exhibits excellent effects in abrasion resistance and antistatic properties.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08L 67/00-67/04

Claims (3)

(57) [Claims] 1. It contains 0.1 to 10% by weight of a crosslinked polymer particle having a thermal decomposition temperature of 350 ° C. or more and a metal sulfonic acid salt represented by the formula (1), and further contains inorganic particles.
Polyester film characterized by that. R (X) _n SO ₃ M (1) (where R represents an alkyl group having 5 to 30 carbon atoms, X represents an aromatic group, n represents 0 to 1, and M represents an alkali metal element) 2. The polyester film according to claim 1, wherein M is a lithium element. 3. An average molecular weight of 1,000 to 200,000.
The polyester film according to claim 1, wherein the content of the polyoxyalkylene glycol is 0.1 to 10% by weight.