JP2977287B2 - Thermoplastic resin film and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin film having uniform and fine projections formed on its surface and a method for producing the same. It relates to the manufacturing method.

[0002]

2. Description of the Related Art Thermoplastic resin films, especially polyester films, are widely used for magnetic tapes, electrics, packaging and the like because of their excellent mechanical and electrical properties.
Especially for magnetic recording media applications, in recent years higher recording density,
Efforts have been made to improve the electromagnetic conversion characteristics with higher quality, longer time, and compactness, and the surface of the base film must be smooth.

From the viewpoint of the electromagnetic conversion characteristics, a base film having a completely smooth mirror surface with no protrusions on the film surface is preferable, but such a film has poor workability such as slipperiness, tape running property and winding property. Is bad. Generally, in order to improve workability such as slipperiness and winding characteristics of a film, a method of reducing friction and a contact area with a film or a roll by applying unevenness to the film surface is adopted. As a method of forming
Conventionally, titanium dioxide, calcium carbonate, talc, kaolin, barium sulfate, aluminum oxide, silicon dioxide,
A method of dispersing a so-called lubricant such as various other inert inorganic compound particles in a synthetic resin for a film or a method of applying the above lubricant on the surface of the film, and particularly, in the case of a polyester film, as a lubricant other than the above, polyester Many proposals have been made, such as the so-called internal particle method, in which particles are formed from salts of terephthalic acid, which is one of raw materials at the time of production, and a metal such as calcium and lithium.

However, in these prior arts, it is general that the larger the size of the film surface projections formed by these particles, the greater the effect of improving the slipperiness. In applications where strong properties are required, the large particles themselves cause defects such as dropout and have the disadvantage that the electromagnetic conversion characteristics are significantly deteriorated. Therefore, it is necessary to make the unevenness of the film surface as fine and uniform as possible.

In the conventional method of adding fine primary particles to the polyester production process, some of the particles aggregate after the addition of the particles, resulting in a wide distribution of the particle size. There was a drawback that fine and relatively large ones were mixed. Similarly, in the method of coating inert inorganic particles on the film surface during the film formation process, part of the particles aggregate in the binder during the drying process after application, and the resulting unevenness on the film surface is uneven. However, the disadvantage of mixing fine and relatively large ones was inevitable.

[0006]

SUMMARY OF THE INVENTION The present invention relates to the above-mentioned conventional disadvantages in the method of forming irregularities on the surface of a film.
That is, an object of the present invention is to solve the problems caused by uneven and coarse protrusions on the film surface caused by aggregation of particles, and to provide a film excellent in slipperiness due to fine and uniform protrusions.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has been studied as a result of using a dispersion of composite particles composed of colloidal inorganic particles and colloidal organic polymer. The present inventors have found that the present invention provides a thermoplastic resin having a uniform and fine projection-like surface state, and further studied based on the findings to complete the present invention.

That is, the present invention is a thermoplastic resin film in which uniform and fine projections composed of composite particles composed of colloidal inorganic particles and colloidal organic polymer are formed on at least one surface of the thermoplastic resin film, and a method for producing the same. And the height of the fine projections is less than 0.2 μm.
And the 0,000 pieces / mm ² or more, the thermoplastic resin film of the surface particles or 0.2μm is 1,000 / mm ² or less, an average particle size of the colloidal inorganic particles are 0.001 5 .mu.m, colloidal organic polymer A method for producing a thermoplastic resin film, which comprises coating a dispersion of composite particles having an average particle size of 0.001 to 1 μm on the film surface, and coating and drying the dispersion of composite particles, and at least in a uniaxial direction. This is a method for producing a thermoplastic resin film, characterized by performing a stretching treatment.

The target thermoplastic resin film obtained by the present invention has uniform and fine projections obtained from composite particles of colloidal inorganic particles and colloidal organic polymer particles on at least one surface. Further, the number of the fine projections is less than 0.2 μm and the number of the projections is 30,000 /
mm ² or more, and the number of protrusions of 0.2 μm or more is 1,000 / mm ²
It is desirable that: Number of protrusions of 0.2μm or more
If the 1,000 / mm ² or more, slip properties, is the preferred direction with respect to workability improvement, such as runnability and winding properties when formed into a tape, in particular satisfy the electromagnetic conversion characteristics are sought on the magnetic tape It will be difficult to do.

The number of protrusions having a size of 0.2 μm or more is set to 1,000 / mm ² or less, and the number of protrusions having a size of less than 0.2 μm is 30,000 / mm 2.
^{If the value is} less than ² , the electromagnetic conversion characteristics are in a preferable direction, but the workability such as slipperiness, tape running properties and winding characteristics deteriorates, which is not preferable.

[0011] The lower limit of the above-mentioned projections smaller than 0.2 µm is 0.00
About 5 μm, more preferably 0.01 μm, and 0.2 μm
m is about 1 μm, more preferably 0.5 μm
It is. The number of protrusions smaller than 0.2 μm is 3 per mm ^2.
It is preferable that the number is 10,000 to 10 million, more preferably 100,000 or more. The number of protrusions of 0.2 μm or more is 1,000 or less.
Those having 0 or less are more preferable. In addition, the height and density of these protrusions are numerical values measured using an analyzer for the stretched final product.

The thermoplastic resin as a raw material in the present invention is:
The composition is not particularly limited, and known compositions can be used as appropriate, but are preferably selected from polyesters, polyolefins, polyamides, cellulose derivatives, vinyls, and the like. More preferably, polyester resin is preferable from the viewpoint of mechanical and thermal stability.

Further, the polyester resin is a crystalline polyester such as polyethylene terephthalate and polyalkylene naphthalate, and polyethylene terephthalate is particularly suitable. In particular, at least 80 mol% of the repeating unit is composed of ethylene terephthalate. Isophthalic acid, p-
β-oxyethoxybenzoic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-dicarboxylic diphenyl,
4,4'-dicarboxylbenzophenone, bis (4-
Carboxyphenyl) dicarboxylic acid components such as ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, cyclohexane 1,4-dicarboxylic acid, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexane dimethanol, ethylene of bisphenol Oxide adducts,
Polyethylene glycol, polypropylene glycol,
Glycol components such as polytetramethylene glycol, p
-An oxycarboxylic acid component such as oxybenzoic acid can be arbitrarily selected and used. In addition, a small amount of a compound containing an amide bond, a urethane bond, an ether bond, a carbonate bond, or the like may be contained as a copolymer component.

Examples of the method for producing the polyester include a so-called direct polymerization method in which an aromatic dicarboxylic acid and a glycol are directly reacted, and a so-called transesterification method in which a dimethyl ester of an aromatic dicarboxylic acid is transesterified with a glycol. Law can be applied. A film having a thickness of 3 to 200 μm is generally used.

The colloid as used in the present invention refers to a suspension or suspension in which spherical particles are in a relatively stable dispersion state.

The colloidal inorganic particles of the present invention include silica, titanium oxide, calcium carbonate, magnesium carbonate, kaolin, clay, zeolite, talc, synthetic aluminum silicate, synthetic calcium silicate, aluminum hydroxide, aluminum oxide, barium sulfate, It is appropriately selected from calcium sulfite, spherical glass fine particles and other various inorganic particles. Any of these may be used,
Particularly preferred in terms of slipperiness and ease of forming composite colloid particles are silica, titanium oxide, aluminum oxide and the like.

The particle size is preferably from 0.001 to 5 μm, more preferably from 0.005 to 0.2 μm. Particles having a particle size of 0.001 μm or less have poor slipperiness, and the desired effect cannot be obtained. On the other hand, if it is 5 μm or more, the projections become coarse, which is not preferable for high-grade magnetic recording applications requiring surface smoothness.

The colloidal organic polymer particles include
It is not particularly limited as long as it is an organic polymer compound having a film-forming function by heating, but is not limited to ester, vinyl, acrylic, styrene, alkyd, urethane, vinylidene, diene, olefin copolymer, amide Systems, epoxy resins, amino resins, other condensation resins such as addition condensation type and polycondensation type, and various synthetic resins such as unsaturated polymerization type, ring opening polymerization type, etc., rubber resins, protein resins, etc. And semi-synthetic and natural resins, and copolymers thereof. Preferred are those having a film-forming temperature of 50 ° C. or lower and good adhesion to the base colloidal inorganic particles, such as ester-based, vinyl-based, and acrylic-based resins. Selected from one or more polymer compounds from the group consisting of styrene and styrene. In addition, from the viewpoint of ease of obtaining colloidal particles, adhesion to the core of colloidal inorganic particles, stability, etc., polymers obtained from acrylic, styrene and other unsaturated monomers Is particularly preferred.

The particle size is preferably 0.001 to 1 μm, more preferably 0.005 to 0.5 μm.
μm. When the thickness is less than 0.001 μm, the protective action of the colloidal inorganic particles is poor and a part of the colloidal inorganic particles is secondary-aggregated during film formation, which is not preferable. 1 μm
Above, it is difficult to exist as composite particles, and the colloidal organic polymer particles are detached from the surface of the colloidal inorganic particles, which is not preferable.

The relative relationship between the particle size of the colloidal inorganic particles and the particle size of the colloidal organic polymer particles is not particularly limited, but the particle size of the colloidal organic polymer particles depends on the particle size of the core colloidal inorganic particles. Preferably smaller. As a method for obtaining such composite particles, for example, a method in which a polymerizable monomer is emulsion-polymerized in a system in which colloidal inorganic particles are present, and a method in which polymer particles are adhered to the surface of the colloidal inorganic particles while generating polymer particles, Using various known methods such as contacting polymer particles polymerized into colloidal particles in a system and colloidal inorganic particles, and attaching the polymer particles to the surface of the colloidal inorganic particles by the attractive force of the mutual surface charge. Obviously, the invention is not limited by these methods.

As a medium for these composite particle colloids, any medium such as water, alcohol, polyhydric alcohol and other organic solvents can be used. Water, alcohol glycols or a mixture thereof can be used for productivity and stability. It is preferable from the point of view.

In the present invention, the use ratio (parts by weight) of the inorganic particles and the organic polymer is generally 1 to 2 to 10 to 10.
0, preferably 1 to 5 to 20. The particle size of the composite particles obtained by coating the colloidal inorganic particles with the colloidal organic polymer particles is 0.005 to 10 μm, and particularly preferably 0.01 to 0.1 μm. Thus, a stable dispersion of the composite particles having the colloidal inorganic particles as the core and the colloidal organic polymer adhered to the surface thereof is obtained. The dispersion of the composite particles is coated on the film surface by a method such as coating, spraying, or dipping.

The coating method of the composite particle dispersion in the present invention can be carried out by a usual method. In particular, an unstretched film after a thermoplastic resin is melt-extruded, or a uniaxial film in a longitudinal or transverse direction. The method of obtaining a biaxially oriented coated film by applying to the film after stretching and then performing heat treatment after stretching in uniaxial or biaxial directions is the method of obtaining the adhesion, transparency and economy of the coating film. Is preferred from the viewpoint of Especially considering the drying property of the coating film, workability, etc., it is coated after being stretched uniaxially in the longitudinal direction,
Further, a method of obtaining a biaxially oriented film by stretching in the transverse direction is particularly preferable. The surface to be coated and the amount of coating vary depending on the purpose and application of the obtained film, but either single-sided coating or double-sided coating is possible. The coating amount (dry weight part) is usually preferably 0.005 to 5 g / m ² as an amount present on the film after biaxial stretching, and is preferably 0.1 to 5 g / m ² .
01 to ² g / m ² is particularly preferred. Coating amount 0.005
If it is less than 5 g, the desired effect cannot be obtained, and if it exceeds 5 g / m ² , adverse effects such as blocking are likely to occur, and a thin film having uniform fine projections is hardly formed.

Before applying the composite particle dispersion,
By subjecting the polyester film to the corona discharge treatment, the coatability of the composite particle dispersion is improved, and the adhesive strength between the polyester film and the formed film of the colloidal organic polymer particles is improved. The coating layer after coating or after biaxial stretching is subjected to corona discharge treatment, ultraviolet irradiation treatment,
By performing an electron beam irradiation treatment, a plasma treatment, or the like, the wettability and adhesion of the film surface can be improved.

The uniform fine protrusions on the film surface obtained according to the present invention can be obtained by the following methods:
It varies depending on the coating amount and the like. For example, when used for a base film for high density magnetic recording, 0.05 μm
Per mm ² of about the height of the projection ~0.1μm 3 × 10
⁴ it is preferable to select a composite particle composition so as to be 10 ⁵ medium density. In order to obtain such a projection height and a projection density, for example, colloidal organic polymer particles having a particle diameter of 0.005 to 0.01 μm are adhered on the surface with spherical colloidal inorganic particles of 0.05 μm as nuclei. Composite particles are particularly preferred.

Another feature of the present invention is that the colloidal organic polymer particles adhered to the inorganic colloid particles form a film at the time of heating after coating, and uniformly fix the inorganic particles without aggregation. This does not preclude the use of other ordinary binder resins or the use of simple inert particles as long as they do not hinder.

[0027]

EXAMPLES Example 1 (1) Preparation of Dispersion for Coating Colloidal silica particles having a particle diameter of 0.08 μm (solid content: 5 parts) were coated with colloidal styrene acrylic copolymer particles having a particle diameter of 0.01 μm (solid content). 45 parts of the composite particles to which (40 parts) were adhered were dispersed in 55 parts of ion-exchanged water. Add this to water 5
The solution was diluted 4.5-fold with a solution of 0 parts and 50 parts of isopropyl alcohol, and thoroughly stirred until uniform to obtain a coating solution.

(2) Production of coated film Polyethylene terephthalate containing almost no particulate matter is melt-extruded at 280 to 300 ° C.
It cooled with the cooling roll of ° C, and obtained the unstretched film about 120 micrometers in thickness. This unstretched film was stretched 3.5 times in the longitudinal direction between a pair of rolls at 85 ° C. having different peripheral speeds. Next, the above-mentioned coating solution was applied by a roll coater method, dried with hot air at 70 ° C., and then was laterally 3.5 at 98 ° C. with a tenter.
Stretched twice and heat-set at 200-210 ° C to a thickness of 10
μ of biaxially stretched coated polyester film was obtained. The solid coating amount of the coating agent was 0.09 g / m ² .

Example 2 A biaxially stretched polyester film was obtained in exactly the same manner as in Example 1 except that the composite particles in which the colloidal inorganic particles were changed to colloidal silica having a particle size of 0.03 μm were used.

Example 3 Example 1 was repeated except that the colloidal inorganic particles used were colloidal titanium oxide particles having a particle size of 0.2 μm and composite particles obtained by changing the particle size of a styrene acrylic copolymer to 0.05 μm.
A biaxially stretched coated polyester film was obtained in exactly the same manner as described above.

Example 4 A biaxially stretched coated polyester film was obtained in exactly the same manner as in Example 1 except that composite particles obtained by changing colloidal organic polymer particles to a polyester copolymer having a particle size of 0.01 μm were used. Was.

Comparative Example 1 Colloidal inorganic particles were added to colloidal silica having a particle size of 7 μm.
A biaxially stretched coated polyester film was obtained in the same manner as in Example 1, except that the organic polymer colloid was changed to composite particles of 1 μm of a styrene acrylic copolymer.

Comparative Example 2 A biaxially stretched coated polyester film was obtained in exactly the same manner as in Example 1, except that the colloidal particles used were not composite particle colloids, but simple silica, and the particle size was 0.08 μm. Was.

Comparative Example 3 Example 1 was repeated except that the colloidal organic polymer particles were changed to composite particles comprising a styrene acrylic copolymer having a particle size of 2 μm.
A biaxially stretched coated polyester film was obtained in exactly the same manner as described above.

COMPARATIVE EXAMPLE 4 Except that the colloidal inorganic particles were a mixture of colloidal silica having a particle size of 0.08 μm and the colloidal organic polymer particles having a particle size of 0.01 μm which did not form composite particles of an acrylic copolymer emulsion binder. A biaxially stretched coated polyester film was obtained in the same manner as in Example 1.

Comparative Example 5 The colloid particles used were not composite particle colloids,
A biaxially stretched coated polyester film was obtained in exactly the same manner as in Example 1 except that the acrylic copolymer colloid of μ was used. Table 1 summarizes the evaluation results of the films obtained in the above examples.

[0037]

[Table 1]

In the table, the coefficient of friction is a value measured according to ASTM-1894 using Tensilon manufactured by Toyo Seiki Co., Ltd., on both the coated surface and the uncoated surface. The average roughness, projection height, and projection density were measured using a non-contact three-dimensional roughness analyzer manufactured by Kosaka Laboratory. Further, the judgment of the coated surface state was carried out by visually judging the obtained coating film surface and photographing by differential interference contrast microscopy, and was classified as follows (Table 2).

[0039]

[Table 2]

As is clear from the above examples, it is understood that the films obtained by the method of the present invention are all excellent in slipperiness and have few coarse projections on the coated surface. Also, if the particle size of the inorganic particles in the composite particles to be added is too large, the number of coarse protrusions increases (Comparative Example 1). If the organic polymer particles in the composite particles to be added are too large, desired characteristics are obtained. It can be seen that this is not possible (Comparative Example 3). When the particles used are not composite particles but a monodispersed solution of each particle, the number of coarse projections increases, and it can be seen that the desired characteristics cannot be obtained (Comparative Example 4).

[0041]

As described above, the present invention employs a dispersion of fine composite particles comprising colloidal inorganic particles and colloidal organic polymer to form uniform and fine projections on the film surface. This eliminates the drawbacks of the conventional method, stably exists in the system as compared with a single colloidal inorganic particle, and eliminates the aggregation and coarsening of the inorganic particles in each step. As a result, it has excellent sliding properties, running properties and winding properties, and also has excellent effects on electromagnetic conversion properties.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C08L 67:00 (72) Inventor Yujiro Matsuyama 2-1-1 Katata, Otsu City, Shiga Prefecture Toyo Spinning Co., Ltd. ( 72) Inventor Katsuro Kuze 2-1-1 Katata, Otsu City, Shiga Prefecture Toyo Spinning Co., Ltd. (56) References JP-A-2-194029 (JP, A) JP-A-1-98634 (JP, A) JP-A-3-240535 (JP, A) JP-A-4-1237 (JP, A) JP-A-4-151231 (JP, A) JP-A-4-180959 (JP, A) Field (Int.Cl. ⁶ , DB name) C08J 5/16-5/18 B29C 55/12

Claims (4)

(57) [Claims] 1. A thermoplastic resin film in which uniform fine protrusions composed of composite particles of colloidal inorganic particles and colloidal organic polymer are formed on at least one surface of the thermoplastic resin film. 2. The height of fine projections on a film is 0.2 μm.
projections of less than m is 30,000 / mm ² or more, the thermoplastic resin film of claim 1 0.2 [mu] m or more projections is 1000 / mm ² or less. 3. A dispersion of composite particles having at least one surface of a thermoplastic resin film coated on the surface of colloidal inorganic particles having an average particle diameter of 0.001 to 5 μm with a colloidal organic polymer having an average particle diameter of 0.001 to 1 μm. A method for producing a thermoplastic resin film, which comprises coating and forming uniform fine projections on the surface. 4. After coating and drying the dispersion liquid of the composite particles,
The method for producing a thermoplastic resin film according to claim 3, wherein the film is stretched in at least one axial direction.