JP2661403B2 - Biaxially oriented thermoplastic resin 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 biaxially oriented thermoplastic resin film.

[0002]

2. Description of the Related Art As a biaxially oriented thermoplastic resin film, there is known a film in which the density of protrusions on at least one side is increased (for example, Japanese Patent Application Laid-Open No. 2-77431).

[0003]

However, in the above-mentioned conventional biaxially oriented thermoplastic resin films, particularly those having a high projection density, for example, a magnetic layer application in a magnetic medium application, a calendering step, or a video tape produced. The process speed of the process of manufacturing soft tapes and the like by dubbing etc. has been increasing more and more recently, and there was a disadvantage that the generation of white powder that the film surface was shaved by a contacting roll or guide could not be completely suppressed. .

An object of the present invention is to provide a biaxially oriented thermoplastic resin film which solves the above-mentioned problems, and in which the film is hardly shaved in a high-speed process (hereinafter, referred to as excellent in abrasion resistance).

[0005]

According to the present invention, there is provided a biaxially oriented thermoplastic resin film according to the present invention, in which a layer (A layer) made of a thermoplastic resin A containing particles is formed by a layer (B) made of a thermoplastic resin B. Layer) on at least one side of the layer, wherein the particle diameter ratio d ₁ / min of the major axis d ₁ and the minor axis d ₂ of the particles is
d ₂ is not more than 1.4, and an average ratio t / d ₂ of the minor diameter d ₂ is 0.1 of particles contained in the thickness t and A layer of the A layer
It is 10, in which a biaxially oriented thermoplastic resin film, wherein the content of the particles in the A layer is 1 to 50 wt%.

The thermoplastic resin A constituting the present invention is not particularly limited, such as polyester, polyolefin, polyamide, polyphenylene sulfide, etc. In particular, polyester, especially ethylene terephthalate, ethylene α,
When at least one structural unit selected from the group consisting of β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate and ethylene 2,6-naphthalate is used as a main component, the abrasion resistance is reduced. It is desirable because it becomes even better.

Further, the thermoplastic resin constituting the present invention is very desirable when it is crystalline or has optical anisotropy when melted, because the abrasion resistance is further improved. The term "crystallinity" as used herein indicates that the material is not amorphous, and quantitatively, the cold crystallization temperature Tcc in the crystallization parameter is detected and the crystallization parameter ΔTcg is 1
It is 50 ° C or less. Further, the heat of fusion (change in enthalpy of fusion) measured by a differential scanning calorimeter is 7.5 ca.
When the crystallinity is 1 / g or more, the wear resistance is further improved, which is very desirable. It is particularly desirable in the case of a polyester containing ethylene terephthalate as a main component, because the abrasion resistance is further improved. Two or more kinds of thermoplastic resins are mixed within a range not to impair the present invention. Or a copolymer may be used.

The particles in the thermoplastic resin A of the present invention have a major diameter d.
The particle diameter ratio d ₁ / d ₂ between ₁ and the minor axis d ₂ is preferably 1.4 or more.
Or 1.6 or more particles. If the particle diameter ratio d ₁ / d ₂ is smaller than the above range, the abrasion resistance becomes poor, which is not preferable.

The size of the particles is not particularly limited. However, when the average minor axis d ₂ in the film is 0.005 to 5 μm and the average major axis d ₁ is 0.01 to 20 μm, the abrasion resistance becomes good. Extremely desirable.

The ratio t / d ₂ of the thickness t of the layer A of the present invention to the average minor axis d ₂ of the particles contained in the layer A is 0.1 to 10, preferably 0.2 to 8, more preferably 0 to 8. .3 to 2. If the ratio t / d ₂ of the thickness t of the A layer to the average minor axis d ₂ of the particles contained in the A layer is less than the above range or conversely, it is not preferable because the wear resistance becomes poor.

The content of the particles in the thermoplastic resin A of the present invention must be 1 to 50% by weight, preferably 1 to 30% by weight, and more preferably 3 to 20% by weight. If the content of the inert particles is less than the above range, or if the content is too large, the abrasion resistance becomes poor, which is not preferable.

The film of the present invention comprises, as a main component, a composition comprising the above-mentioned thermoplastic resin and particles. Other types of polymers may be blended or an antioxidant as long as the object of the present invention is not impaired. Organic additives such as heat stabilizers, lubricants and ultraviolet absorbers may be added to the extent that they are usually added.

The film of the present invention is a film in which the above composition is biaxially oriented. A uniaxial or non-oriented film is not preferable because abrasion resistance becomes poor. The degree of this orientation is not particularly limited, but the Young's modulus, which is a measure of the degree of molecular orientation of the polymer, is 350 k in both the longitudinal and width directions.
The g / mm ² or more is very desirable because the wear resistance is further improved. The upper limit of the Young's modulus, which is a measure of the degree of molecular orientation, is not particularly limited.
About 0 kg / mm ² is the manufacturing limit.

The thickness of the thermoplastic resin A layer of the present invention is not particularly limited, but is preferably from 0.01 to 3 μm, more preferably from 0.02 to 2 μm, because the wear resistance is further improved. Especially desirable.

The average height of protrusions on the surface of the thermoplastic resin A film of the present invention is 5 to 500 nm, preferably 10 to 3 nm.
When the thickness is in the range of 00 nm, and more preferably in the range of 15 to 200 nm, the wear resistance is further improved, which is particularly desirable.

As described above, it is highly desirable that the thermoplastic resin constituting the film of the present invention is crystalline or has a melt optical anisotropy. In the case of a melt isotropic film, the crystallization parameter ΔTcg is 25 to 65. C is particularly desirable because the wear resistance is further improved.

When the thermoplastic resin A is a polyester, it is particularly preferable that the refractive index in the thickness direction of the surface of the thermoplastic resin A is 1.5 or less, because the abrasion resistance is further improved.

Further more excellent wear resistance when the major diameter d ₁ axis and the film surface angle θ is 45 ° or more particles of particles contained in film A layer of the present invention is 20% or less of all particles This is particularly desirable.

The film of the present invention is obtained by laminating a film of the thermoplastic resin A on at least one surface of a film of the thermoplastic resin B and then using the film in a biaxially oriented film.
This is very desirable because not only the mechanical properties are improved, but also the wear resistance is further improved. Here, the thermoplastic resins A and B may be the same or different.

As the thermoplastic resin B, a crystalline polymer is desirable, and in particular, a crystalline parameter ΔTcg is 20 to 10
When the temperature is in the range of 0 ° C., the wear resistance is further improved, which is desirable. Specific examples include polyesters, polyamides, polyphenylene sulfides, and polyolefins, and polyesters are particularly preferable because the wear resistance is further improved. Examples of the polyester include ethylene terephthalate and ethylene α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate.
In particular, when at least one structural unit selected from ethylene 2,6-naphthalate units is used as a main component, the abrasion resistance is particularly improved, which is preferable. However, other components may be copolymerized within a range that does not impair the present invention and within a range that does not impair desired crystallinity, preferably within 5 mol%.

The thermoplastic resin B of the present invention may be blended with other polymers as long as the object of the present invention is not impaired, and may be an antioxidant, a heat stabilizer, a lubricant, an ultraviolet absorber, etc. May be added to the extent that the organic additives are usually added.

It is not particularly necessary for the thermoplastic resin B film to contain particles, but the average particle diameter is 0.007 to 0.007.
0.005 particles of 2 μm, especially 0.01-0.5 μm
When the content is -1% by weight, particularly 0.007-0.8% by weight, not only the abrasion resistance is further improved, but also the winding appearance of the film is improved, which is very desirable. Crystallization parameter Δ of thermoplastic resin A and thermoplastic resin B
The difference (A−B) in Tcg is not particularly limited, but is −30 to 30.
In the case of + 20 ° C., wear resistance is further improved, which is particularly desirable.

Next, a method for producing the film of the present invention will be described.

First, as a method for incorporating particles into the thermoplastic resin A, when the thermoplastic resin is a polyester, the particles are dispersed in the form of a slurry of ethylene glycol as a diol component, and this ethylene glycol is dispersed. It is effective to polymerize with a predetermined dicarboxylic acid component to obtain a film having the relationship between the thickness and the average particle size and the content in the range of the present invention. Further, the melt viscosity of the polyester containing the particles, the copolymerization component, etc. are adjusted to adjust the crystallization parameter ΔTc.
The method of keeping g in the range of 40 to 65 [deg.] C. is effective for obtaining a film having the relationship between the thickness and the average particle size and the content in the range of the present invention.

The method of heat-treating the ethylene glycol slurry of the particles at a temperature of 140 to 200 ° C., particularly 180 to 200 ° C., for 30 minutes to 5 hours, especially 1 to 3 hours, is preferred in the present invention. It is effective to obtain a film having a relation between the particle diameters and the content.

As a method for incorporating particles into the thermoplastic resin, the particles are heat-treated in ethylene glycol, mixed with the thermoplastic resin in the form of a slurry in which the solvent is replaced with water, and a vent-type twin-screw extruder is used. kneaded to relationship between the thickness and the average particle diameter of the method is also the scope of the invention kneaded into the thermoplastic resin using, is very effective to obtain a film of content.

As a method of adjusting the content of particles, a high-concentration master is prepared by the above-described method, and the master is diluted with a thermoplastic resin containing substantially no particles at the time of film formation to adjust the content of particles. Is effective.

After the pellets containing a predetermined amount of particles are dried as necessary, the predetermined thermoplastic resin A composition and thermoplastic resin B (A and B may be the same or different) may be melted in a known manner. It is supplied to a laminating extruder, extruded into a sheet from a slit die, and cooled and solidified on a casting roll to produce an unstretched film. That is,
Using two or three extruders, two or three layers of manifolds or merging blocks, laminating thermoplastic resins A and B, extruding two or three layers of sheets from a die, cooling with a casting roll and unstretching Make a film. In this case, the polymer flow passage of the thermoplastic resin A, a method of installing a static mixer, a gear pump relationship between the thickness and the average particle size of the range of the present invention, is effective to obtain a film content. The relationship between the thickness and the average particle diameter of the present invention ranges to the melting temperature of the thermoplastic resin A side of the extruder higher 5 to 40 ° C. than the thermoplastic resin B side, the content, the alignment state of the desired range Film It is effective to get In this case, the relationship between the thickness and the average particle diameter in the range of the present invention is to set the ratio of the die slit gap / the thickness of the unstretched film at the time of extrusion molding to the unstretched film to be in the range of 5 to 30, preferably 8 to 20. is effective to obtain a film having a range of content.

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, stretching in the longitudinal direction is divided into three or more stages, and the total longitudinal stretching ratio is 3.0 to 6.5. The method is effective for obtaining a film having the relationship between the thickness and the average particle size and the content in the range of the present invention. The stretching temperature in the longitudinal direction varies depending on the type of the thermoplastic resin, and cannot be generally described. However, it is usually 50 to 130 ° C. for the first stage and higher than the second stage. It is effective to obtain a film having a relation of particle size, content and oriented state in a desirable range.
The longitudinal stretching speed is preferably in the range of 2,000 to 50,000% / min. As a stretching method in the width direction, a method using a stenter is generally used. The stretch ratio is suitably in the range of 3.0 to 5.0 times. Stretching speed in the width direction is 1,000 to 20,000
% / Min, and the temperature is preferably in the range of 80 to 160 ° C. Next, this stretched film is heat-treated. In this case, the heat treatment temperature is preferably 170 to 230 ° C, particularly 180 to 220 ° C, and the time is preferably 0.5 to 60 seconds.

[0030]

[Method for measuring physical properties and method for evaluating effects] The method for measuring characteristic values and the method for evaluating effects according to the present invention are as follows.

(1) Average particle size of particles The cross section of the film (section thickness, about 1000 angstroms) was measured with a transmission electron microscope (JEM-1200 manufactured by JEOL Ltd.).
EX) to observe particles (100,000 times magnification) and detect particles. The longest particle diameter among the individual particles is defined as a long diameter D,
Further, the shortest particle diameter is determined as the short diameter d. This measurement was repeated 500 times at different locations, and the average value of the total number N of the measured particles was determined. That is, it is obtained by the following equation. Major axis d ₁ = ΣD _i / N Minor axis d ₂ = Σd _i / N

[0032] (2) an angle formed long diameter D axis and the film surface of the individual particles in the measurement of angle θ (1) formed by the major axis d ₁ axis and the film surface of the particles were measured for all particles was obtained.

(3) Content of Particles A solvent in which the thermoplastic resin is dissolved but the particles are not dissolved is selected, the particles are centrifuged from the thermoplastic resin, and the particle content is defined as a ratio (% by weight) to the total weight of the particles. I do.
In some cases, the combined use of infrared spectroscopy is also effective.

(4) Thickness of Layer A 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 the analysis in the thickness direction is performed from the surface to a depth of 3000 nm. 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 surface particle concentration is 1/1 of the maximum value.
A depth of 2 (this depth is deeper than the depth of the maximum value) was determined, and this was defined as the lamination thickness.

Measurement device Secondary ion mass spectrometer (SIMS) A-DIDA3000 manufactured by ATOMIKA (Germany) 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 The organic polymer particles are the particles most contained in the range from the surface layer to the depth of 3000 nm. In the case of SIMS, it is difficult to measure by SIMS, so XPS (X
Line photoelectron spectroscopy), IR (infrared spectroscopy) or the like to measure the depth profile similar to the above, and obtain the layer thickness. The interface can be recognized from the difference to determine the lamination thickness.

(5) Crystallization parameter ΔTcg, heat of fusion Measured using a differential scanning calorimeter. The measurement conditions are as follows. That is, 10 mg of a sample is set in a differential scanning calorimeter, melted at a temperature of 300 ° C. for 5 minutes, and then rapidly cooled in liquid nitrogen. The quenched sample is heated at a rate of 10 ° C./min, and the glass transition point Tg is detected. The temperature is further increased, and the crystallization exothermic peak temperature from the glassy state is set to the cold crystallization temperature T.
cc. The temperature was further increased, and the heat of fusion was determined from the melting peak. Here, the difference between Tcc and Tg (Tcc-Tg) was defined as a crystallization parameter ΔTcg.

(6) Average height of surface projections Image processing is performed on the measured heights of projections when scanning is performed with a scanning electron microscope of a two-detector system and a cross-section measuring apparatus with the height of the flat surface of the film set to 0. To the device and reconstruct the film surface projection image on the image processing device. In addition, this 2
The highest value among the individualized projection portions is regarded as the height of the projection, and this is determined for each individual projection. This measurement was repeated 500 times at different locations, and the average value of the heights of all the measured protrusions was defined as the average height. As for the magnification of the scanning electron microscope, a value between 1,000 and 10,000 times is selected.

(7) Young's modulus According to the method specified in JIS-Z-1702,
Using an Instron type tensile tester, 25
It measured at 65 degreeC and 65% RH.

(8) Intrinsic viscosity [η] (unit: dl / g) A value calculated from the following equation from the solution viscosity measured in orthochlorophenol at 25 ° C. is used. That is, η _SP / C = [η] + K [η] ² · C, where η _SP = (solution viscosity / solvent viscosity) −1, and C is the weight of dissolved polymer per 100 ml of solvent (g / 100 ml,
Usually 1.2), K is a Haggins constant (0.343). The solution viscosity and the solvent viscosity were measured using an Ostwald viscometer.

(9) Abrasion resistance The film was slit to a width of 1/2 inch to obtain a tape having a length of 1 m. A continuous loop was run at both ends with a stainless steel guide pin having a diameter of 5 mm at a tension of 500 g and a speed of 2000 m / min. The amount of white powder generated on the pin after 24 hours was examined, and the following ranking was performed. Rank excellent: Almost no white powder is generated. Good: White powder is slightly generated, but does not hinder use for video applications. Poor rank: White powder is often generated and cannot be used for video applications.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on embodiments.

Example 1 (Table 1) An ethylene glycol slurry containing kaolin particles having a major axis / minor axis ratio of 2.0 was prepared, and the ethylene glycol slurry was heat-treated at 190 ° C. for 1.5 hours. After transesterification with dimethyl terephthalate, polycondensation was carried out to produce polyethylene terephthalate pellets containing 5 % by weight of the particles. At this time, the polycondensation time was adjusted to make the intrinsic viscosity 0.65 (thermoplastic resin A). In addition, a polyethylene terephthalate having an intrinsic viscosity of 0.62 and containing substantially no particles was produced by a conventional method, and was designated as a thermoplastic resin B. 180 ° C each of these polymers
For 6 hours under reduced pressure (3 Torr). The thermoplastic resin A is supplied to the extruder 1 and melted at 290 ° C., and the thermoplastic resin B is supplied to the extruder 2 and melted at 285 ° C., and these polymers are combined and laminated by a combined block (feed block). The film was wound around a casting drum having a surface temperature of 25 ° C. using an electrostatic application casting method, and cooled and solidified to form an unstretched film having a two-layer structure. At this time, an unstretched film was prepared with the ratio of die slit gap / unstretched film thickness being set to 10. Further, the discharge amount of each extruder was adjusted to adjust the total thickness and the thickness of the thermoplastic resin A 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 stages with a difference in peripheral speed between two sets of rolls. This uniaxially stretched film was stretched 4.0 times in the width direction at 100 ° C. at a stretching speed of 2,000% / min using a stenter, and was heat-treated at 210 ° C. for 5 seconds under a constant length to give a total thickness of 1
A biaxially oriented laminated film having a thickness of 5 μm and a thickness of the thermoplastic resin A layer of 0.5 μm was obtained. As described above, when the ratio of the major axis / minor axis, the content, and the ratio of the lamination thickness to the particle diameter contained in the layer A are within the range of the present invention, a film having excellent wear resistance is obtained. Can be.

Examples 2-3 , Comparative Examples 1-5 (Table 1) In the same manner as in Example 1, the major axis of the particles contained in the layer A /
Films with various ratios of minor axis, content, and ratio of lamination thickness to particle size were prepared. When the particle size ratio, the content and the ratio of the lamination thickness to the particle size are within the range of the present invention, the abrasion resistance was excellent, but if not, a film having good abrasion resistance can be obtained. Did not.

[0044]

[Table 1]

[0045]

According to the biaxially oriented thermoplastic resin film of the present invention, projections having a high projection density and being hard to be cut are formed on at least one surface by a predetermined particle size ratio and content. The film surface is hardly scraped even during high-speed process running, and excellent abrasion resistance without generation of white powder can be exhibited.

Continuation of the front page (56) References JP-A-2-77431 (JP, A) JP-A-3-113717 (JP, A) JP-A-2-11640 (JP, A) JP-A-2-84445 (JP) , A)

Claims (2)

(57) [Claims] 1. A film in which a layer (A layer) made of thermoplastic resin A containing particles is laminated on at least one side of a layer (B layer) made of thermoplastic resin B, wherein the major diameter d of the particles is ₁ and minor axis particle diameter ratio d ₁ / d ₂ of d ₂ is not more than 1.4, and the ratio t / d of the average minor diameter d ₂ of the particles contained in the thickness t and a layer of the a layer ₂ is 0.1 to 10, biaxially oriented thermoplastic resin film, wherein the content of the particles in the a layer is 1 to 50 wt%. 2. The method according to claim 1, wherein the major axis of the particles contained in the layer A is d ₁ axis.
Particles having an angle θ of 45 ° or more formed by
The biaxially oriented thermoplastic resin film according to claim 1, which is 0% or less.
Film.