JP3296075B2 - Laminated polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a superior dispersibility of the particles, it relates to a laminated polyester film excellent in abrasion resistance.

[0002]

2. Description of the Related Art In general, polyesters represented by polyethylene terephthalate and the like have excellent mechanical properties and chemical properties and are widely used as molded articles such as films and fibers. When processed into a biaxially oriented film or the like, its slipperiness and abrasion resistance greatly affect the workability in the manufacturing process, the working process in various applications, or the use of the product. For example, when used as a base film for a magnetic tape, if the slipperiness and abrasion resistance 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. In addition, abrasion powder of the film is likely to be generated, and a coating omission occurs in a step of applying the magnetic layer, which causes a drop out of magnetic recording. When used as a magnetic tape, VT
Abrasion powder is generated due to contact running with various guide pins in the R deck, causing dropout.

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, since these particles are generally hard and have low affinity with polyester, they easily fall off due to external force received in a film manufacturing process such as a calendar process or contact running during recording / reproduction, and are likely to cause deterioration in slipperiness and dropout. .

As a method for improving the affinity between the particles and the polyester, surface treatment of inorganic particles, use of particles made of an organic polymer, and the like have been proposed. For example, as surface treatment of inorganic particles, JP-A-63-128031 (surface treatment with a polyacrylic acid-based polymer),
JP-A-2-235353, JP-A-63-234039 (phosphorus compound treatment), JP-A-62-223239, JP-A-63-31345 (coupling agent treatment), JP-A-63-304038 JP-A-63-280763 (Surface treatment by glycol grafting) has been proposed, and organic particles include JP-B-63-4563.
No. 409, JP-A-59-217755, JP-A-2-189359, etc., have proposed crosslinked polymer fine particles. However, the abrasion resistance required as the performance of the film becomes higher becomes higher. Is coming. Therefore, for example, even if the particles are originally excellent in monodispersibility, if the particles are aggregated and coarse particles are present in the polyester production stage, there will be a problem in the subsequent molding process as described above.

[0005]

SUMMARY OF THE INVENTION As a result of intensive studies, the present inventors have found that a polyester composition obtained by adding a slurry containing a specific amount of sodium atoms and having a specific pH range has a high degree of purity. It has been found that the particles have excellent particle dispersibility and are excellent in falling-off resistance of particles when formed into a molded product such as a film.

[0006]

An object of the present invention is to provide a crosslinked polymer particle having an average particle diameter d of 0.005 to 3 μm in a weight ratio of 500 ppm or more in terms of NaOH.
A layer comprising a polyester composition obtained by adding a slurry containing sodium atoms of 000 ppm or less and having a slurry pH of 6 or more and 9 or less at any production stage or after production of the polyester composition.
When the thickness of this layer is t, the following expression is satisfied.
This can be achieved by adding a laminated polyester film . 0.2d ≦ t ≦ 10d

The polyester used in the present invention is produced from a dicarboxylic acid containing an aromatic dicarboxylic acid as a main acid component, an ester-forming derivative thereof, and glycol. Here, examples of the aromatic dicarboxylic acid include terephthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and isophthalic acid. Examples of the glycol component include aliphatic glycols such as ethylene glycol, butanediol, tetramethylene glycol, and hexamethylene glycol, and alicyclic diols such as cyclohexanedimethanol. As the polyester, for example, those containing alkylene terephthalate or alkylene naphthalate as a main component are preferable. These polyesters may be homopolymers or copolymers. Examples of the copolymerization component include aliphatic dicarboxylic acids such as adipic acid and sebacic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid, polyethylene glycol, polypropylene glycol, and 5-sodium sulfoisophthalic acid. No. In particular, it is preferable to copolymerize a compound having a sulfonic acid group or a metal salt thereof in an amount of 0.1 to 5% by weight, preferably 0.1 to 3% by weight, since the dispersibility of the crosslinked polymer particles is improved.

[0008] The composition of the crosslinked polymer particles in the present invention is not particularly limited, and may be any particles as long as at least a part of the particles is composed of a crosslinked polymer insoluble in polyester. Specifically, the crosslinked polymer particles generally include a monovinyl compound (A) having only one aliphatic unsaturated bond in a molecule and a compound having two or more aliphatic unsaturated bonds in a molecule as a crosslinking component. And a copolymer with (B).

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,
Methacrylic acid ester monomers such as benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, N, N'-dimethylaminoethyl methacrylate;
Mono- or dicarboxylic acids and acid anhydrides of dicarboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, and amide monomers such as acrylamide and methacrylamide can be used. Compound (A) above
As such, 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,
Polyhydric acrylates and methacrylates such as 1,3-butylene glycol dimethacrylate, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate are exemplified. Among these compounds, it is particularly preferable to use divinylbenzene, ethylene glycol dimethacrylate or trimethylolpropane trimethacrylate.

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, the crosslinked polymer particles may be produced in a system of three or more components.

The organic polymer fine particles of the present invention have a particle dispersibility in a polymer when the pyrolysis temperature (10% weight loss temperature, nitrogen gas flow, heating rate 10 ° C./min) by a thermobalance is 350 ° C. or more. However, it is particularly preferable. It is more preferably at least 360 ° C, particularly preferably at least 370 ° C. Further, because of such high heat resistance, the degree of crosslinking of the crosslinked polymer particles is 5% or more, more preferably 8% or more, and particularly preferably 20% or more.
% Is preferable. The type of the cross-linking agent is not particularly limited, but divinyl benzene is particularly preferable, and pure divinyl benzene is used in an amount of 5% by weight or more, more preferably 8% by weight or more, especially 20% by weight or more based on all monomers forming an organic polymer. Is preferred.

Here, the degree of crosslinking is defined by the formula (1) with respect to all the organic components constituting the particles. Degree of crosslinking = (weight of crosslinking component in raw material monomer) / (total weight of raw material monomer) × 100 (%) (1)

As a method for producing the crosslinked polymer particles of the present invention, for example, a method such as emulsion polymerization or suspension polymerization can be mentioned, but from the viewpoint of particle dispersibility, emulsion polymerization is preferred. For emulsion polymerization, the compounds (A) and (B)
After mixing, there is the following production method. (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) JP-A-54-97582 and JP-A-54-97582
-126288, a polymerization method using Eugelstatt or the like. (E) A polymerization method using no swelling aid in the method of (d).

Here, the seed particles used in the method (b) may be the same or different in composition from the polymer comprising the compounds (A) and (B), and may or may not be copolymerized with the polymer. No problem. The same applies to the composition of the polymer forming the core and the polymer forming the shell in (C).

The average particle size of the crosslinked polymer particles of the present invention is preferably from 0.005 to 3 μm, more preferably from 0.01 to 2 μm. If the thickness is less than 0.01 μm, the slipperiness of the film becomes insufficient, and if it exceeds 3 μm, the abrasion resistance may deteriorate. Here, the average particle diameter is a number-based circular equivalent average diameter.

The slurry of the crosslinked polymer particles in the present invention needs to have a sodium atom content of 500 ppm or more and 10,000 ppm or less in terms of NaOH with respect to the particles, and a pH of the slurry of 6 or more and 9 or less.
When the content of the sodium atom is out of the above range, the dispersion state of the particles in the slurry becomes insufficient, and as a result, the particles aggregate in the polyester composition. The content of sodium atoms is preferably 100
The content is preferably from 0 ppm to 7000 ppm. Also, when the slurry pH is out of the above range, when the slurry is added to the polyester, the particle agglomeration increases, which is presumed to be due to the significant deterioration of the polyester. The pH of the slurry is particularly preferably from 7.5 to 8.5.

The method of adding sodium atoms to the slurry in the present invention is not particularly limited as long as it is before the slurry is added to the polyester production step. For example, a method of adding sodium atoms in the form of an aqueous NaOH solution after synthesizing the particles may be mentioned. Can be

The method and timing for adding the particles in the present invention to the polymer raw material are known in the art, for example, in the case of polyester, a method of adding powder or glycol slurry to the polyester reaction system, It is possible to adopt a method of kneading the polyester in the form of a slurry using a low boiling point solvent such as water. Among them, 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 less 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. At this time, in the slurry of the particles, sodium dodecylbenzenesulfonate, anionic surfactants such as sodium lauryl sulfate, polyoxyethylene nonyl phenyl ether, nonionic surfactants such as polyethylene glycol monostearate, polyvinylpyrrolidone, polyvinyl It is preferable to contain a protective agent such as alcohol and carboxymethyl cellulose from the viewpoint of particle dispersibility. 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.

Further, the water and / or boiling point of the particles
The concentration of the slurry of the organic compound at 0 ° C. or lower is not particularly limited. However, if the amount of water and / or the organic compound having a boiling point of 200 ° C. or lower is 2% by weight or more and 30% by weight or less based on the polymer, Is good, and the intrinsic viscosity of the polymer does not decrease. More preferably 2
% By weight or more and 20% by weight or less.

Further, the polyester composition of the present invention includes:
Lithium, sodium, calcium, magnesium, manganese, zinc, commonly used in the production of polyester
Antimony, germanium, metal compound catalysts such as titanium, a phosphorus compound as a coloring inhibitor, and, in addition to the particles of the present invention, at least one of alkali metals and alkaline earth metals and phosphorus as a part of the constituent components It may contain particles precipitated in the polyester polymerization reaction system, that is, internal particles.

When the polyester composition of the present invention is used as a film, it can be applied to either a single layer or a laminate. However, from the viewpoint of running properties and abrasion resistance, at least one layer of the film layer of the present invention is laminated. Is preferred. 3
When applied to a laminated film having more than one layer, the layer composed of the polyester composition of the present invention is preferably at least one outermost layer of the laminated film from the viewpoint of abrasion resistance, and particularly preferably both outermost layers. Particularly preferred. From the viewpoint of abrasion resistance, the relation between the particle diameter d and the film layer thickness t of the larger one of the crosslinked polymer particles (X) and the particles (Y) is 0.2 d. ≤
t ≦ 10d, preferably 0.5d ≦ t ≦ 5d, particularly preferably 0.5d ≦ t ≦ 3d.

[0023] In addition, from the viewpoint of abrasion resistance,
It is preferable that the number of projections on at least one side is 2 × 10 ^{3 to} 5 × 10 ⁵ / mm ² . The number of projections on at least one side is preferably 3 × 10 ³ to 4 × 10 ⁵ / mm
² , more preferably 5 × 10 ^{3 to} 3 × 10 ⁵ pieces / mm ²
It is.

Next, a method for producing such a film will be described. After drying the pellets containing a predetermined amount of particles as necessary, feed them to a known melt laminating extruder, extrude them into a sheet from a slit die, cool and solidify on a casting roll to make an unstretched film . That is, the polyester in a molten state is laminated using two or 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 of the polymer containing particles is effective for further improving the effect of the present invention.

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.

[0027]

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

A. Particle Properties (1) Average Particle Diameter The film is cut into ultra-thin sections having a thickness of about 0.1 μm, and the cross section is observed with a transmission electron microscope at a magnification of 100,000 or more. The circle equivalent diameter was measured for each particle image. The measurement was performed for 1000 particles, and the number-based average diameter was calculated.

(2) Content of Particles A solvent in which the polymer dissolves but the particles do not dissolve is selected, and the particles are centrifuged from the polymer, and the ratio (% by weight) to the total weight of the particles is defined as the particle content.

(3) Dispersibility of Particles in Polyester The polyester containing the crosslinked polymer particles was cut to produce an ultra-thin section having a thickness of about 0.1 μm.
Observe with a transmission electron microscope at a magnification of 10,000 times or more. 100
The measurement was performed for zero particles, and the number of aggregated particles in which two or more particles were aggregated was determined.

B. Film properties (1) Laminated thickness of laminated film Using a secondary ion mass spectrometer (SIMS), the carbon and the elements originating from the particles having the highest concentration among the particles in the film having a depth of 3000 nm from the surface layer and polyester The concentration ratio of the element (M ⁺ / C ⁻ ) is defined as the particle concentration, and the analysis in the thickness direction from the surface to the 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.

Measuring device Secondary ion analyzer (SIMS) Atomika, Germany
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. 5kV-3.0A

When the particles most contained in the range from the surface layer to the depth of 3000 nm are organic polymer particles, the SI
Since measurement is difficult with MS, the depth profile may be measured by XPS (X-ray photoelectron spectroscopy), IR (infrared spectroscopy) or the like while etching from the surface layer to determine the layer thickness. The lamination thickness can also be determined by recognizing the interface from a change in particle concentration or a difference in contrast due to a difference in polymer by cross-sectional observation using a microscope or the like.
Further, after the laminated polymer is peeled off, the laminated thickness can be determined using a thin film step measuring device.

(2) Abrasion Resistance A tape having a film width of 1/2 inch is slit and 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.

[0035]

The present invention will be described in more detail with reference to the following examples. Further, the value of the addition amount in each table is the particle content in the film.

Example 1 A polyethylene terephthalate chip having an intrinsic viscosity of 0.65 was melted using a vent-type twin-screw extruder, and crosslinked polymer particles (ethylvinylbenzene / divinylbenzene copolymer particles) ) Was added to obtain a polyethylene terephthalate (I) containing crosslinked polymer particles.

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 of trimethyl phosphate as a heat stabilizer. 0.03 parts by weight,
Polyethylene terephthalate (II) having an intrinsic viscosity of 0.65 was obtained by an ordinary 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 by an electrostatic application casting method and cooled and solidified to produce an unstretched film. This unstretched film is 3.5
Twice, stretched 5.5 times in the width direction, heat treated, total thickness 15 μm
Was obtained. As shown in Table 1, the properties of this film were good in abrasion resistance.

Examples 2 and 3 and Comparative Examples 1 and 3 In the same manner as in Example 1, films having different types of particles were obtained. The thickness of the laminate was changed, and a single-layer film was prepared. As shown in Table 1, the polyester films in the range of the present invention had good abrasion resistance, but those not so were insufficient.

[0041]

[Table 1]

[0042]

Since the polyester composition of the present invention is produced from a slurry having a specific sodium atom content and pH, it has good particle dispersibility and excellent abrasion resistance when molded into a film or the like.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 67/00-67/04

Claims (1)

(57) [Claims] 1. A weight ratio of 500 pp in terms of NaOH to bridging polymer particles having an average particle diameter d of 0.005 to 3 μm.
A slurry containing 10000ppm following sodium atom or m, and if any manufacturing stage or polyester composition obtained by adding after production of the slurry polyester composition is a slurry pH of 6 to 9
And the thickness of this layer is t
A laminated polyester film that satisfies the following formula: 0.2d ≦ t ≦ 10d