JPH0455376B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a film with a flattened surface and a method for producing the same, and more specifically, the present invention relates to a film with a flattened surface and a method for manufacturing the same, and more specifically, the present invention relates to a film with a flattened surface and a method for manufacturing the same, and more particularly, the present invention relates to a film with a flattened surface and a method of manufacturing the same. This invention relates to a film and its manufacturing method. BACKGROUND OF THE INVENTION Polymer films are used for various purposes, and among them polyester films are used as a base for information recording media because of their excellent mechanical, thermal, and scientific properties. In particular, polyethylene terephthalate films are used as the base of magnetic recording media. When such a polymer film has a large coefficient of friction between the films or during running, it becomes difficult to wind it up or run stably, so efforts have been made to impart slipperiness. As a method of imparting slipperiness, a method is usually used in which fine irregularities are formed on the film surface to make the surface rough. For example, there is a method of dispersing fine particles in a polymer to form fine protrusions on the film surface. However, the film obtained by this method is roughened on both sides, and if a magnetic layer is provided on it, the electromagnetic conversion characteristics will change depending on the degree of roughening. In other words, the rougher the surface, the lower the electromagnetic conversion characteristics. do. on the other hand,
From the viewpoint of film slipperiness, a rougher surface is preferable. As can be understood from the above, it was necessary to take these contradictory characteristics into consideration when designing the surface of the film. On the other hand, this problem can be solved if there is a base film that has a flat magnetic surface and a rough running surface on the back side.
However, in the past, it was believed that special techniques such as coextrusion and lamination were required to create such a dual structure. Furthermore, a method of coating with a film is known as a means for imparting easy slipping or adhesion. This lubricity imparting is a coating with an uneven coating, and the adhesion imparting is a primer coating treatment to increase the adhesion between the base film and the magnetic layer, but the coated surface is uneven. None showed improved flatness. Purpose of the Invention The present inventor has arrived at the present invention as a result of intensive studies from all angles on means for flattening an uneven surface. An object of the present invention is to provide a polymer film whose surface fine irregularities are reduced by a thin film of a thin film-forming substance in a specific proportion, and a method for manufacturing the same. A further object of the present invention is to provide a film having a flattened surface which provides excellent magnetic transduction properties when a magnetic layer is provided on the surface. Structure and Effects of the Invention According to the present invention, the main feature 1 is to have a large number of fine protrusions on the film surface, and these fine protrusions reduce the center line average surface roughness (Rao).
A thin layer of a thin film-forming substance on at least one side of the polymer film in the range of 0.005 to 0.5 μm, with a layer thickness that mainly fills in between the microscopic protrusions but leaves a contribution to the centerline average surface roughness of the protrusions. With this thin film, the center line average surface roughness (Rap) is 0.001.
2. A film with a flattened surface characterized by a flattened surface of 0.05 μm, and 2. A film with the following formula 10 ^-2 ≦P′/R′ao≦10 ² [Here] where P′ is the amount of layer of thin film-forming substance after completion of crystal orientation (g/m ² ), R′ao is center line average surface roughness (μm) of the polymer film after completion of crystal orientation, 0.005 ~0.5μm range. ] Achieved by the method for producing a film according to item 1 above, which is characterized in that a layer of a thin film-forming substance satisfying the following is provided, and then preheating, stretching, and heat treatment are performed to complete the oriented crystallization of the polymer film. Ru. In the present invention, the polymer film refers to a film made of polymers such as polyester, polyamide, polyamideimide, polyesterimide, polyurethane, vinyl copolymer, cellulose polymer, and polyvinyl chloride, but in particular polyester Film is preferred. Polyester is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative, such as polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate. , poly(1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-naphthalene dicarboxylate, copolymers thereof, or blends of these with small proportions of other resins. It is something that Among these, polyethylene terephthalate, poly(1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-
Naphthalene dicarboxylate and the like are preferred. In addition, the film before the completion of crystal orientation is either a polymer film in an unstretched state (sometimes slightly oriented in the extrusion direction) made by thermally melting a polymer and extruding it as it is, or refers to a film that has been stretched in either the vertical or horizontal direction. The polymer film in the present invention has a large number of fine protrusions on its surface, and these fine protrusions have a center line surface roughness (Rao) in the range of 0.005 to 0.5 μm. These fine protrusions are usually caused by a lubricant contained in the polymer. As this lubricant, any conventionally known or used lubricant can be used, and inert fine particles are usually used. In the present invention, examples of thin film-forming substances include polymer resins, low-molecular organic substances, inorganic substances, and more specifically polyurethane, polyester, acrylic resins, epoxy resins, vinyl resins,
Polymeric resins such as polyvinyl alcohol, polyamide, melanin resin, polyamideimide, polyimide, polyethylene glycol, silicone resin, fluororesin, phenoxy resin, polyether, polyether ester, polyolefin wax, fatty acids, fatty acid salts, fatty acid esters , low-molecular organic substances such as polyols, silicone oils, silane coupling agents, oligomers, oils, waxes, etc.
Examples of inorganic substances include silicon oxide, titanium oxide, magnesium oxide, aluminum oxide, iron oxide, iron, cobalt, nickel, alloys, zinc, aluminum, carbon black, calcium carbonate, barium carbonate, glass, and tin oxide. . Among these, preferred examples include polyester, polyurethane, acrylic resin, polyester and silicon oxide fine particles, and polyurethane and silicon oxide fine particles. These substances are used in the form of aqueous liquids, solutions, dispersions, vapors, melts or solids. Among these, it is preferable to use an aqueous liquid. In the present invention, known methods can be applied as means for providing a thin film of a thin film-forming substance on the surface (one or both surfaces) of the polymer film. For example, coating methods such as roll coating method, roll brush coating method, spray coating method, air knife coating method, impregnation method, curtain coating method, method of forming a thin metal layer by vapor deposition method, sputtering method, etc., hot melt coating method A method of coating a molten material can be applied. Among these, the coating method is preferred. Such a thin layer by itself (in other words, when no thin layer is provided) ultimately forms a surface with a centerline average surface roughness (Rao) of 0.005 to 0.5 μm, or on the formed polymer film, It is provided with a layer thickness that mainly fills in between the many fine protrusions that are formed on the surface, but still contributes to the centerline average surface roughness of the protrusions, and this thin layer is used to improve the centerline average surface roughness. Surface roughness (Rap) is reduced to 0.001-0.05μm. This reduction in surface roughness is achieved by expressing the relationship between Rao above and the amount of thin layer (p) using the following formula (1) 10 ^-2 ≦P/Rao≦10 ² ... (1) [Here, P is the amount of thin film formed. Amount of layer of sexual substance (g/
m ² ), Rao is the centerline surface roughness (μm) of the polymer film. ] This can be easily achieved by satisfying the following. When P/Rao<10 ^-2 , flattening is not sufficient,
Moreover, if P/Pao>10 ² , the surface will be roughened rather than flattened, which is not preferable. The thin layer may be formed at any time; for example, the film may be formed after biaxial orientation crystallization has been completed, or may be formed before crystal orientation is completed. Of these, the latter is preferred. When applied to a film before the completion of crystal orientation, the following formula (2) 10 ^-2 ≦P′/R′ao≦10 ² ...(2) [Here, P′ is the thin film forming substance after the completion of crystal orientation. layer amount (g/m ² ), R′ao is the centerline average surface roughness of the polymer film after completion of crystal orientation (μ
m), which is in the range of 0.005 to 0.5 μm. ] A layer of a thin film-forming substance that satisfies the above is provided, and then preheating, stretching, and heat treatment are performed to complete the oriented crystallization of the polymer film, resulting in a center line average surface roughness.
The film has a surface of 0.001 to 0.05 μm.
This film satisfies the above formula (1).
The thin layer may be formed to fill only the recesses of the polymer film, as shown in Figure 1, or it may be formed to cover the entire surface of the polymer film, but mainly fill the recesses, as shown in Figure 2. It may be formed in a state. When the thin film-forming substance is used as an aqueous solution (coating), it is preferable to add a nonionic, anionic or cationic surfactant to the aqueous solution. Examples of such surfactants include known polyoxyethylene alkyl or phenol ethers, aliphatic acid esters, fatty acids, sorbitan esters, higher alcohol sulfate ester salts, alkyl sulfonates, and the like. The appropriate solid content concentration of the coating liquid is normally 20 wt% or less. The coating amount is adjusted appropriately depending on the degree of flattening required, but is 0.005 to 50 g/m ² , more preferably 0.02 to 30 g/m 2 .
g/m ² is preferred. At that time, additives such as antistatic agents, ultraviolet absorbers, pigments, organic fillers, inorganic fillers, lubricants, and antiblocking agents may be used in combination as long as the purpose of the present invention is not lost. In addition, the process of applying coating is
The surface layer of the base material is preferably used immediately after dissolving and extruding the polymer and casting (unstretched film) or immediately after being stretched in either the vertical or horizontal direction, but the film may be formed after stretching is completed. Films made using the wet method (polyamideimide, etc.)
In this case, materials that do not undergo any stretching may also be covered. The coating liquid may be dried by air drying or heating drying.
Of course, when the coating treatment is performed during the film forming process, it is performed by heating and drying, and the drying may be performed independently or may be performed concurrently with preheating for stretching. The heating drying temperature is
It is preferable to select from the range of 50 to 240℃, for example, 100℃ for about 5 seconds, 110℃ for about 5 seconds, 90℃ for about 5 seconds.
It is best to heat it for about 20 seconds. For stretching, heat treatment (heat setting), etc. of the film, conventionally well known methods and conditions can be used. In the present invention, if one side of the polymer film is flattened, it becomes a film with a dual structure, which can satisfy both flatness and slipperiness at the same time.Furthermore, when both sides are flattened, it is possible to unify the polymer brand, and the base protrusion has a large base protrusion. It is possible to create a specific surface shape that only protrudes, and it is also possible to embed brimers that exhibit specific performance into the rough valleys (recesses) of the base to add other functions without impairing the original characteristics of the base. It has the advantage of being able to The surface-flattened film of the present invention is particularly useful for magnetic tape bases, floppy disk bases, etc., but is also useful for other general industrial film bases. EXAMPLES The present invention will be explained in more detail with reference to Examples below. In addition, various values in the specification are measured and defined as follows. (1) PV value The surface condition of the film was measured using a stylus type surface roughness meter (Surcom3B) made by Tokyo Seimitsu Co., Ltd.
2μ, load 0.19g, film standard length 26mm
50 times the reference length direction and 2 times the surface roughness direction
Enlarge it 10,000 times, draw a chart, select the line that passes through the bottom of the first valley from the highest among the straight lines that are parallel to the average line of the section cut out by the standard length from the cross-sectional curve, and select the vertical line between the two straight lines. The value divided by the magnification (PV value) is expressed in microns (μ),
It is expressed as the average value of these 10 PV values. (2) Ra value [center line average surface roughness] Obtain a film roughness curve using the same device as in (1) above, and measure the measured length L (reference length 2) in the direction of the center line.
mm) is removed, and the roughness curve is expressed as Y=f(x) with the center line of this removed portion as the X-axis and the direction of vertical magnification as the Y-axis.The value given by the following formula is Expressed in microns (μ). Ra=1/L∫ ^L ₀ |f(x)|dx In this measurement, the reference length is 0.25 mm, 8 measurements are taken, 3 are excluded from the direction with the largest value, and the average value of the remaining 5 is expressed. Example 1 Polyester resin synthesized from sebacic acid, 1,6-hexanediol and neopentyl glycol, aqueous solution of polyurethane synthesized from 1,6-hexane diisocyanate and sodium dimethylolpropionate (in polyurethane)
The nonionic surfactant polyoxyethylene nonyl phenyl ether (HLB = 13.0, solid content ratio 16 wt%) was added to the COO group content 2.0 wt%), and a final water dispersion coating liquid with a solid content concentration of 12 wt% was prepared. It was adjusted.
[Coating liquid A] Polyethylene terephthalate containing a lubricant (heat of crystal fusion 9.8 Cal/g) with a polymer intrinsic viscosity of 0.62 measured in osochlorophenol at 25°C was extruded from a die using an extruder and cooled to 40°C. An unstretched film with a thickness of 152 μm was obtained while applying an electrostatic charge on a drum, and then this was stretched 3.6 times in the longitudinal direction on a metal roll heated to 93° C., and the coating solution A was applied to the kiss coating method. It was applied to one side of a uniaxially stretched film. The average coating amount at that time was 1.1g/m ²
(solid content equivalent). Continue horizontally at 102℃
Stretched 3.6 times and further heat treated at 220℃, thickness 12.0μ
A biaxially stretched polyester film was obtained. Measure the center line average surface roughness Rap value etc. of this film,
The results shown in Table 1 were obtained. Comparative Example 1 The same procedure as in Example 1 was carried out except that coating liquid A was not applied. The centerline average surface roughness, Rao value, etc. of the obtained film were measured, and the results shown in Table 1 were obtained. Example 2 The same procedure as in Example 1 was carried out except that a mixture of polyethylene terephthalate (85 wt%) having an intrinsic viscosity of 0.62 and polybutylene terephthalate (15 wt%) having an intrinsic viscosity of 0.73 was used instead of polyethylene terephthalate. Ivy. Measure the center line average surface roughness Pap value etc. of the obtained film,
The results shown in Table 1 were obtained. Example 3 Coating solution A of Example 1 was applied to one side of a biaxially stretched polyethylene terephthalate film (stretched 3.5 times in length and 3.6 times in width) with a thickness of 12.3μ by a key coating method.
g/m ² (solid content equivalent) was coated and heat treated at 130°C for 4 minutes. The centerline average surface roughness, Rap value, etc. of the obtained film were measured, and the results shown in Table 1 were obtained. Example 4 In Example 1, the average coating amount of 1.1 g/m ² was reduced to 0.46
The same procedure as in Example 1 was carried out except that the concentration was changed to g/m ² . The centerline average surface roughness (Rap value), etc. of the obtained film were measured, and the results shown in Table 1 were obtained. Example 5 Acrylic emulsion synthesized from methyl methacrylate, ethyl acrylate, butyl acrylate, glycidyl methacrylate, acrylamide, N-methoxymethylacrylamide and ammonium acrylate (COO ^- group content in the acrylic resin was 2.8 wt) %) and the nonionic surfactant polyoxyethylene nonyl phenyl ether (HLB=
12.7, solid content ratio 15 wt%) and silicon oxide fine particles (average particle size 0.03μ, solid content ratio 14 wt%) were added to prepare an aqueous dispersion coating liquid with a final solid content concentration of 14 wt%.
[Coating liquid B] The same procedure as in Example 1 was carried out except that coating liquid B was used instead of coating liquid A. The centerline average surface roughness (Rap value), etc. of the obtained film were measured, and the results shown in Table 1 were obtained. Example 6 Polyester synthesized from terephthalic acid, isophthalic acid, 5-Na sulfoisophthalic acid, 1,4-butanediol, ethylene glycol and neopentyl glycol (-
A nonionic surfactant polyoxyethylene nonyl phenyl ether (HLB = 13.0, solid content ratio 14 wt%) was added to SO ₃ Na group content 3.8 wt%), and a final water dispersion coating with a solid content concentration of 12 wt% was applied. The liquid was adjusted.
[Preparation of Coating Solution] The same procedure as in Example 1 was carried out except that Coating Solution C was used instead of Coating Solution A and that the film was coated on both sides instead of on one side. The centerline average surface roughness (Rap value), etc. of the obtained film were measured, and the results shown in Table 1 were obtained.

【table】

[Table] * Center line average surface roughness of polyester base film Example 7 A polyester synthesized from terephthalic acid, isophthalic acid, adipic acid, ethylene glycol, neopentyl glycol and diethylene glycol was dissolved in tetrahydrofuran and finally solidified. A coating solution with a concentration of 10 wt% was prepared. [Coating liquid D] The same procedure as in Example 3 was carried out except that coating liquid D was used instead of coating liquid A. The centerline average surface roughness, Rap value, etc. of the obtained film were measured, and the results shown in Table 2 were obtained. Example 8 Polyester synthesized from terephthalic acid, isophthalic acid, sebacic acid, ethylene glycol, neobentyl glycol, diethyl glycol, and 1,4-butanediol was made into a biaxially stretched polyethylene terephthalate film with a thickness of 100 μm (length: 3.4
Stretched 3.7 times horizontally) by hot melt method on one side
It was coated at 0.63 g/m ² and heat treated at 200°C. The centerline average surface roughness, Rap value, etc. of the obtained film were measured, and the results shown in Table 2 were obtained.

【table】 [Brief explanation of the drawing]

FIG. 1 and FIG. 2 are schematic enlarged cross-sectional views showing the state of forming a thin layer of a thin film-forming substance. 1: base film, 2: thin layer.

Claims (1)

[Claims] 1. The film has many fine protrusions on its surface, and these fine protrusions have a center line average surface roughness (Rao).
A thin film of a thin film-forming substance is applied to at least one side of the polymer film having a thickness in the range of 0.005 to 0.5 μm, with a layer thickness that mainly fills in between the fine protrusions but leaves a contribution to the centerline average surface roughness of the protrusions. A film with a flattened surface, characterized in that the thin film has a centerline average surface roughness (Rap) of 0.001 to 0.05 μm. 2 The thin layer of the film-forming substance has the following formula: 10 ^-2 ≦P/Rao≦10 ² [where P is the amount of the layer of the film-forming substance (g/
m ² ), Rao is the center line average surface roughness (μm) of the polymer film. ] The first claim characterized in that it satisfies the following.
Film mentioned in section. 3. The film according to claim 1 or 2, wherein the thin film-forming substance is polyurethane, polyester, or acrylic resin. 4. On the surface of the polymer film before crystal orientation is completed,
The following formula 10 ^-2 ≦P′/R′ao≦10 ² [Here, P′ is the amount (g/m ² ) of the layer of the thin film-forming substance after the completion of crystal orientation, and R′ao is the amount of the layer of the thin film-forming substance after the completion of crystal orientation. The centerline average surface roughness of the polymer film (μ
m) is in the range of 0.005 to 0.5 μm. ] A layer of a thin film-forming substance satisfying the following is provided, and then preheating, stretching, and further heat treatment are performed to complete the oriented crystallization of the polymer film, which has a large number of fine protrusions on the film surface, These fine protrusions mainly fill the space between the fine protrusions on at least one side of the polymer film whose centerline average roughness (Rao) is in the range of 0.005 to 0.5 μm, but the contribution of these protrusions to the centerline average surface roughness is A method for producing a film, in which a thin layer of a thin film-forming substance is provided with a layer thickness such that the center line average surface roughness (Rap) is reduced to 0.001. 5. The method for producing a film according to claim 4, wherein the thin film-forming substance is polyurethane, polyester or acrylic resin.