JP3254929B2 - Polyester composition and film comprising the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This invention relates to polyester compositions. More specifically, when made into a film, etc.,
The present invention relates to a polyester composition having excellent abrasion resistance.

[0002]

2. Description of the Related Art Due to its excellent properties, polyesters are widely used in various fields including films for magnetic tapes, electrics, photographs, metallizations and packaging. In particular, polyethylene terephthalate film and polyethylene-2,6-naphthalate film are excellent in flatness, mechanical strength, chemical properties, dimensional stability and the like, and are suitably used for base films of magnetic recording media.

[0003] In a magnetic recording medium base film, flatness, slipperiness, abrasion resistance and the like of the film surface are required. For example, in video tape applications, the surface of the base film is required to be flatter to improve recording accuracy. However, when the surface becomes flat, the slipperiness of the film is reduced, and the friction and abrasion of the surface are increased, causing many adverse effects such as scratching of the film surface and generation of shavings. If the abrasion resistance is low, a lot of shaving powder of the film is generated during the manufacturing process of the magnetic tape, and a coating loss occurs in a process of coating the magnetic layer, which causes dropout of magnetic recording. Also, when a magnetic tape is used, the inside of the device runs in contact with the device, and if shavings are generated at the time of contact, dropout occurs.

[0004] Films are added with particles for imparting slipperiness to form irregularities on the surface to reduce friction, but on the other hand, due to the demand for improved wear resistance, particles that form projections that are more difficult to fall off are required. Have been. As such particles, inorganic particles represented by silica and the like have recently been proposed as particles composed of an organic polymer in JP-A-55-99948 and JP-A-1-129038. Although the wear resistance is somewhat improved by using these organic particles as compared with the inorganic particles, there are cases in which the high wear resistance required in recent years is insufficient.

In addition to the slipperiness and abrasion resistance of the base film, it has been studied to make the base film thinner as typified by a higher density of the magnetic recording medium. There is an increasing demand for higher elastic modulus to maintain stiffness.

[0006] We have intensively studied these problems and problems, and have found that a polyester composition containing organic polymer particles in an aggregated form exhibits good properties in terms of slipperiness and abrasion resistance when formed into a film or the like. I started.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a polyester composition and a film which are excellent in slipperiness and abrasion resistance when formed into a film or the like.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an "average 1".
Organic polymer particles having a secondary particle diameter of 0.005 to 0.1 μm and an average secondary particle diameter of 0.05 to 1.5 μm
To 2.0% by weight of a polyester composition ".

The polyester in the present invention may be any polyester capable of forming a film, for example, polyethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalate, polyethylene-1 , 2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate, and the like,
Polyethylene terephthalate or polyethylene
2,6-Naphthalate is preferred, and polyethylene-2,6-naphthalate is particularly preferred when a high elastic modulus is required.

These polyesters include, as copolymerization components, dicarboxylic acids such as adipic acid, isophthalic acid, sebacic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid and ester-forming derivatives thereof, polyethylene glycol, diethylene glycol, Dioxy compounds such as methylene glycol, neopentyl glycol, and polypropylene glycol, oxycarboxylic acids such as p- (β-oxyethoxy) benzoic acid, and ester-forming derivatives thereof may be copolymerized.

The organic polymer particles in the present invention are not particularly limited, and may be any particles as long as at least a part thereof is insoluble in polyester. As a material of such particles, various materials such as polyimide, polyamide imide, polymethyl methacrylate, formaldehyde resin, phenol resin, polystyrene, and polysilsesquioxane so-called silicone resin can be used, but the heat resistance is high. Particularly preferred are vinyl-based crosslinked polymer particles from which particles having a uniform particle size distribution can be easily obtained.

The vinyl-based crosslinked polymer particle is 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.

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 ester monomers such as methyl acrylate, ethyl acrylate, propyl alkylate, hexadecyl acrylate, octyl acrylate, dodecyl acrylate, hexadecyl acrylate, glycidyl acrylate, N, N'-dimethylaminoethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl Methacrylate, isopropyl methacrylate, butyl methacrylate, sec-butyl methacrylate, acrylic methacrylate, phenyl Methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-
Methacrylic acid ester monomers such as hydroxyethyl methacrylate, glycyl methacrylate, N, N'-dimethylaminoethyl methacrylate, etc., and anhydrides of mono- or dicarboxylic acids and dicarboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid And amide monomers such as acrylamide and methacrylamide.

As the compound (A), styrene, ethylvinylbenzene, methyl methacrylate and the like are 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,
Examples include polyvalent acrylates and methacrylates such as 1,3-butylene glycol dimethacrylate.

Of the compound (B), it is particularly preferred to use divinylbenzene, ethylene glycol dimethacrylate or trimethylolpropane trimethacrylate.

Preferred examples of the composition of the vinyl-based crosslinked polymer particles include divinylbenzene polymer, ethylvinylbenzenedivinylbenzene copolymer, styrenedivinylbenzene copolymer, and styrene-ethylvinylbenzene-divinylbenzene copolymer. Examples include a polymer, an ethylene glycol dimethacrylate polymer, a styrene-ethylene glycol dimethacrylate copolymer, and a methyl methacrylate-divinylbenzene copolymer. However, the present invention is not limited to these examples.
It may be a copolymer system of components or more.

There is a method for producing such vinyl polymer particles by, for example, mixing the compounds (A) and (B) and subjecting them to emulsion polymerization as described below. (A) A soap-free polymerization method, that is, a method in which no emulsifier is used or polymerization is performed using an extremely small amount of an emulsifier. (B) A seed polymerization method in which polymer particles are added to a polymerization system prior to emulsion polymerization and emulsion polymerization is performed. (C) A core-shell polymerization method in which a part of the monomer component is emulsion-polymerized, and the remaining monomer is polymerized in the polymerization system. (D) A polymerization method using Eugelstatt and the like described in JP-A-54-97582. (E) A polymerization method using no swelling aid in the method of (d).

The organic polymer particles of the present invention may be subjected to a thermal decomposition temperature (10% weight loss temperature, nitrogen flow, heating rate 1) using a thermobalance.
Particles having a heat resistance of 0 ° C./min or more at 350 ° C. or more are agglomerated during the production of the polyester composition, at the time of melt molding, or at the time of collecting and reusing the molded product. The temperature is preferably 360 ° C. or higher, more preferably 370 ° C. or higher.

The present invention relates to a fine particle comprising organic polymer particles.
It is characterized in that the secondary particles form secondary particles by appropriate aggregation.

The average primary particle diameter of the organic polymer particles in the present invention is from 0.005 to 0.1 μm. The average secondary particle diameter is 0.05 to 1.5 μm, more preferably 0.05 to 1 μm, and particularly 0.1 to 1.0 μm.
If the average secondary particle diameter of the organic polymer particles is less than 0.05 μm, the film will have insufficient slipperiness,
If it exceeds m, the wear resistance becomes insufficient.

When the organic polymer particles in the present invention have a uniform particle size distribution, projections are more uniformly formed on the film surface, and the mixing of coarse particles is reduced, so that the slipperiness and abrasion resistance are improved. Become. Specifically, the relative standard deviation of the particle size distribution of the secondary particle diameter of the organic polymer particles is 0.5
Or less, more preferably 0.3 or less, particularly preferably 0.15 or less.

It is not clear why the organic polymer particles in the aggregated form as in the present invention exhibit good abrasion resistance.
It is considered that polyester, which is a matrix, partially enters the gaps between the primary particles due to the coagulated form and is entangled with the particles, so that it may not easily fall off when formed into a film or the like.

The content of the organic polymer particles in the present invention is from 0.01 to 2.0% by weight, preferably from 0.05 to 2.0% by weight, particularly preferably from 0.1 to 2.0% by weight, based on the polyester.
~ 0.5% by weight. If the content is less than 0.01% by weight, the film is not sufficiently slippery, and if it exceeds 2.0% by weight, the abrasion resistance becomes insufficient, which is not preferable.

The polyester composition of the present invention can be used at any time during the usual polyester production, for example, during the transesterification reaction or the polymerization reaction in the case of transesterification,
Alternatively, at any time in the case of the direct polymerization method, a method of adding the organic polymer particles in the form of a powder or a glycol slurry, or a method of kneading the polyester in the form of a powder or a slurry using a low-boiling solvent is employed. It is possible. Especially water and / or boiling point of particles 200 ° C
The following method of kneading the polyester in the form of an organic compound slurry is preferable because the dispersibility of the particles becomes good. In this case, it is more preferable to use a vent type extruder for deaeration.

At this time, an organic surfactant such as anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium dialkylsulfosuccinate, and formalin condensate of naphthalenesulfonic acid are added to the organic polymer particle slurry. , Nonionic surfactants such as polyoxynonylphenol ether, polyethylene glycol monostearate and sorbitan monostearate, or water-soluble natural polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol water-soluble synthetic polymers, gelatin, starch, etc. It is preferable to add a polymer, a water-soluble semi-synthetic polymer such as carboxymethyl cellulose, etc., because the particle dispersibility in the slurry and the particle dispersibility in the case of forming a polyester composition are good.

In the film comprising the polyester composition of the present invention, inorganic particles such as silicon oxide, titanium oxide, aluminum oxide, calcium carbonate, zirconium oxide and the like may be used in addition to the organic polymer particles as long as the object of the present invention is not impaired. Further, particles that are precipitated in a polyester polymerization reaction system containing at least one of an alkali metal and an alkaline earth metal and phosphorus as a constituent component, that is, particles such as internal particles may be contained.

As a method for producing a polyester film simultaneously containing inorganic particles or internal particles and the organic polymer particles of the present invention, for example, a polyester composition obtained by adding both to a polyester reaction system is formed into a film. Alternatively, a method of blending and melting and kneading master chips separately mixed with a polymer before or during film formation may be employed.

The film comprising the polyester composition of the present invention can be applied to either a single-layer film or a laminated film, but from the viewpoint of surface flatness, at least one film comprising the polyester composition of the present invention is laminated. Film is preferred. It is more preferable that the laminated film has a structure of three or more layers, and it is particularly preferable that the film made of the polyester composition of the present invention is at least one outermost layer of the laminated film having a three-layer structure.

It is particularly preferable from the viewpoint of abrasion resistance that the film made of the polyester composition of the present invention is disposed on the outermost layer, the thickness t of the film layer and the average secondary particle size of the organic polymer particles. D is 0.2D ≦ t ≦ 10
D, preferably 0.5D ≦ t ≦ 5D, particularly preferably 0.5D ≦ t ≦ 3D, and the outermost layer preferably has a thickness of 0.005 to 1 μm, more preferably 0 0.01 to 0.5 μm, particularly 0.02 to 0.3 μm
μm.

[0031] Also, from the point of abrasion resistance,
Preferably, the number of protrusions on at least one side is 2 × 10 ^{3 to} 5 × 10 ⁵ / mm ² . Preferably 3 × 10 ³
４4 × 10 ⁵ / mm ² , especially 5 × 10 ^{3 to} 3 × 10
⁵ pieces / mm ² .

Next, a method for producing a film comprising the polyester composition of the present invention will be described by taking a laminated film as an example.

After drying a pellet containing a predetermined amount of the organic polymer particles and, if necessary, other particles in the present invention, the pellets are supplied to a known melt extruder, extruded into a sheet from a slit die, and cast on a casting roll. It is cooled and solidified to make an unstretched film. In the case of a laminated film, the molten polyester is laminated using two or more extruders, two or more layers of a manifold or a merging block. In this case, a method in which a static mixer and a gear pump are installed in a flow path containing 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 160 ° C, and the total longitudinal stretching ratio is 3. 0-7.0
And the longitudinal stretching speed is preferably in the range of 5,000 to 50,000% / min. As a 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, 3.0 to 7.0 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 220 ° C. and the time is 0.5 to
A range of 60 seconds is preferred.

[0036]

The present invention will be described in detail below with reference to examples. Each characteristic value of the obtained film was obtained according to the following method.

(1) Average particle size Basically, the particles in the polyester composition are measured directly. However, when the refractive index of the particles and the polymer are close to each other and observation is difficult,
In cases where the distinction is complicated when inorganic particles are used in combination, it was determined from the powder or slurry before addition to the polyester.

(A) When measuring from powder or slurry: Place the particles on a sample stage of an electron microscope so that the particles do not overlap as much as possible, and use a scanning electron microscope or a transmission electron microscope.
The particles were observed at a magnification of 10,000 to 100,000 times. In the case of a scanning electron microscope, a platinum vapor-deposited film having a thickness of about 200 angstroms was previously formed on the surface of the sample by a sputtering apparatus. Measure the primary and secondary particle diameter of at least 200 particles from the screen or photographic image as the area equivalent diameter,
The volume-based average particle diameter was calculated based on the volume of each particle calculated from the area equivalent diameter.

(B) When measuring from a film The film is cut in the longitudinal direction (MD direction) at the time of film formation to produce an ultra-thin section having a thickness of about 0.1 μm, and is cut in the TD direction (at right angles to MD in the film plane). ), The cross section was observed with a transmission electron microscope at a magnification of 10,000 to 100,000 times. Measure the primary and secondary particle diameters of at least 200 particles from the screen or photographic image as the area equivalent diameter, and calculate the volume-based average particle diameter based on the volume of each particle calculated from the area equivalent diameter did.

(2) Particle Content The particle content is calculated from the amount of the particles in the polyester as the film material, or the obtained film is dissolved in a solvent that does not dissolve the particles, and the particles are obtained by centrifuging the polymer. The ratio (% by weight) to the total weight of the film was defined as the particle content.

(3) Lamination Thickness of Laminated Film Using a secondary ion mass spectrometer (SIMS), an element and polyester originating from the particles having the highest concentration among the particles in the film ranging from the surface layer to a depth of 3000 nm are used. 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 which 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.

Measuring 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) Slipperiness of film Slit to a film width of 1/2 inch, and a tape running tester TBT-300 type [manufactured by Yokohama System Laboratory Co., Ltd.]
Was used, and the vehicle was run in a 20 ° C., 60% RH atmosphere, and the initial friction coefficient μk was determined by the following equation. The guide diameter is 6
mmφ, and the guide material is SUS27 (surface roughness of 0.
2S), winding angle is 180 °, running speed is 3.3cm
/ Sec. μk = 0.733 × log (T ₁ / T ₂ ) T ₁ : Outgoing side tension T ₂ : Incoming side tension If the above μk is 0.35 or less, the sliding property is good.

(5) Abrasion resistance of the film A tape-like roll obtained by slitting the film to 1/2 inch is wound around a stainless steel SUS-304 guide roll at an angle of 60 °, at a speed of 300 m / min, at a tension of 95 g at 10 g.
The paper was rubbed over a length of 00 m, and ranked according to the amount of white powder generated on the guide roll surface as follows. A and B grades were accepted. Class A: No white powder is generated. Class B: A small amount of white powder is generated. C Class: Some white powder is generated.

Example 1 A polyethylene terephthalate chip having an intrinsic viscosity of 0.64 was melted using a vent type twin screw extruder, and ethylvinylbenzene-divinylbenzene copolymer particles were used as organic polymer particles. Average primary particle diameter 0.05 μm, average secondary particle diameter 0.5 μm, relative standard deviation 0.15 of particle size distribution of secondary particle diameter, thermal decomposition temperature 37
A water slurry at 0 ° C. was added to obtain polyethylene terephthalate (I) containing two kinds of organic polymer particles.

On the other hand, a particle-free polyethylene terephthalate (II) having an intrinsic viscosity of 0.62 was obtained by a known method.

After drying the two polymers (I) and (II) under reduced pressure, the extruder 1 and the extruder 2 feed the polymer (I),
After supplying and melting (II) respectively and filtering with high precision,
Three layers were laminated at the rectangular junction (laminated structure: polymer (I) / polymer (II) / polymer (I).

This was wound around a casting drum using an electrostatic application casting method and cooled and solidified to prepare an unstretched film. The unstretched film is placed in a longitudinal direction of 4.0.
Twice, stretched 5.5 times in the width direction, heat treated, total thickness 15 μm
Was obtained.

From the particle concentration of the pellets subjected to film formation, the amount of organic polymer particles contained in the laminated portion of the obtained film was 0.4% by weight. The lamination thickness was 1 μm in both lamination portions.

The μk of this film was 0.26, and the abrasion resistance was class A. Good characteristics were obtained for the slipperiness and abrasion resistance.

Examples 2 to 3 and Comparative Examples 1 to 3 In the same manner as in Example 1, the composition, particle size, content, lamination conditions, or matrix of the organic polymer particles contained were changed to polyethylene-2,6- A film was prepared in the same manner except that the film was changed to naphthalate. As shown in Table 1, the polyester film in the range of the present invention exhibited good surface flatness, slipperiness, abrasion resistance and winding properties, but if not, any of the properties was insufficient. there were.

[0052]

[Table 1]

[0053]

The polyester composition of the present invention is excellent in slipperiness and abrasion resistance and can be suitably used for magnetic recording media.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 67/00-67/02

Claims (6)

(57) [Claims] An average primary particle diameter of 0.005 to 0.1 μm
m, a polyester composition comprising 0.01 to 2.0% by weight of organic polymer particles having an average secondary particle diameter of 0.05 to 1.5 μm. 2. Polyester is polyethylene-2,6-
The polyester composition according to claim 1, wherein the polyester composition is naphthalate. 3. The organic polymer particles have a thermal decomposition temperature of 350 ° C.
Claim 1 or Claim 2 characterized by the above.
Item 7. The polyester composition according to Item 1. 4. The polyester composition according to claim 1, wherein the relative standard deviation of the particle size distribution of the secondary particle size of the organic polymer particles is 0.5 or less. 5. The polyester composition according to claim 1, wherein the number of protrusions on at least one side is 2 × 10 ^{3 to} 5 × 10 ⁵ / mm ^2. Film. 6. A film comprising the polyester composition according to claim 1 in at least one layer, containing an average secondary particle diameter D of organic polymer particles and containing the crosslinked polymer particles. A laminated polyester film, wherein the relationship with the thickness t of the layer to be formed satisfies Expression (1). 0.2D ≦ t ≦ 10D (1)