JPS622986B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyester film with improved surface characteristics for use in magnetic tapes, mold release, optical applications, electronic copying, capacitors, and the like. Conventionally, films used for each of the above-mentioned applications are desired to have improved runnability in terms of production and quality, such as increased processing speed and reduced scratches. In addition, there is an increasing demand for a smooth base film surface for high-density recording on magnetic tapes and the like. However, smoothing the surface generally increases the friction coefficient of the base film, which deteriorates the running properties of the so-called magnetic tape. Furthermore, in applications other than magnetic tapes, there is a strong demand for improved transparency and smoothness, and these impair running performance. For example, the winding performance during polyester film production or processing of those films,
This results in a decrease in work speed and a decrease in quality due to scratches, etc. For example, in the case of a polyester film for a capacitor, the film surface must have smoothness to increase the corona generation voltage and smoothness to allow winding of the device. In this way, it is possible to satisfy the generally contradictory characteristics of surface smoothness and ease of transport.
This has become one of the focuses for improving polyester films, and various studies have been carried out heretofore. Known methods include adding fine inorganic particles to raw materials for polyester films, controlling the size and amount of internal particles generated due to polymerization catalyst residue, and controlling the amount of particles to maintain smoothness. Coextrusion of a raw material and a raw material containing particles for imparting slipperiness is common. However, the former has the disadvantage that it is difficult to balance smoothness and slipperiness, and the latter has drawbacks such as particles inside the slippery layer and protrusions on the surface that affect the smooth layer, impairing the smoothness of the surface. . An object of the present invention is to provide a polyester film with greatly improved running performance. In order to achieve the above object, the present invention comprises a base film formed from crosslinkable silicone and a silane coupling agent on at least one side, and
The component ratio of the silicone and silane coupling agent is 0.01 to 1 silicone to silane coupling agent.
It is characterized by a polyester film formed by closely adhering a film designated as No. 5. The base film referred to in the present invention refers to polyethylene terephthalate alone, crystalline copolymers mainly composed of polyethylene terephthalate, mixed polymers, polyethylene 2 and 6
A resin containing 80 wt% or more of the structural unit of PET or PEN, such as naphthalate alone or a crystalline copolymer or mixed polymer mainly composed of naphthalate. After melt-molding this resin by known means, It includes general biaxially stretched polyester films that have been stretched and oriented in the horizontal direction and heat-set, and the mechanical properties of the film are F-5 value (5
A balanced type film whose strength (% elongation) is balanced at 12Kg/mm2 ^or less in both the vertical and horizontal directions, especially the vertical F-
5 value, 14 to 25 Kg/mm ² , or F-5 value both vertically and horizontally, 14 to 20 Kg/mm ² , or only horizontal direction F-5 value, reinforced to 14 to 25 Kg/mm ² . Axially oriented polyester film is preferred. In addition, the surface of the base film has a surface roughness.
It is desirable that the surface roughness is from 0.003 to 0.020μ, preferably from 0.004 to 0.015μ, and by keeping the surface roughness within this range, both runnability and smoothness can be achieved. The crosslinkable silicone that is the main component of the film of the present invention may be any silicone polymer that can cause a crosslinking reaction, such as OH group-containing dimethylpolysiloxane, epoxidized dimethylpolysiloxane, methylhydrodienepolysiloxane, or , those in which part or all of the methyl group is substituted with a phenyl group, and those modified with melamine, amine, etc., but are not necessarily limited thereto. As the silane coupling agent, either polyester resin or crosslinkable silicone, or
It is an organosilicon low-molecular compound that has a reactive group that binds to both, and the reactive groups include methoxy group, ethoxy group, silanol group, vinyl group, epoxy group,
It is necessary to have one or more methacrylic groups, amino groups, mercapto groups, chloro groups, hydroxyl groups, carboxyl groups, etc., singly or in combination. The component ratio of silicone and silane coupling agent is 1 silicone to 0.01 silane coupling agent.
-5 Preferably 0.02-4 is required; below this range, durability and adhesion will decrease; when this range is exceeded, durability will also decrease. Apart from the first two, the concentration of surfactant is 0.001 to 2% by weight.
is preferred. Note that organic solvents, inorganic pigments, antifoaming agents, and thickeners may be added as long as they do not interfere with the purpose of the present invention. The method of forming a film composed of a crosslinkable silicone and a silane coupling agent according to the present invention is to disperse the crosslinkable silicone and a silane coupling agent in a known dispersion medium to form an emulsion or solution, and then apply the film to a polyester film by a known method. Apply,
It is then formed by heat treatment at 160°C to 230°C, preferably 180°C to 220°C. The coating amount needs to be 1 to 1000 mg/m ² in terms of solid content, preferably 2 to 500 mg/m ² .If it is less than this range, there will be no effect of improving lubricity, and if it is more than this, the durability will be poor. Application methods include methods of applying to a film that has already been biaxially oriented, methods of applying to a film that has only been uniaxially oriented, then re-stretching and stretching again, and methods of applying to an unoriented film and then stretching biaxially. Any method may be used, but particularly good performance is obtained when the coating is applied to a non-oriented film or a film after uniaxial stretching. Further, in the case of coating, there are no particular restrictions on the selection of the solvent or dispersion medium for the necessary crosslinkable silicone and silane coupling agent. In order to improve wettability and adhesiveness, it is necessary to add a surfactant. As the surfactant, nonionic surfactants are particularly suitable. Next, regarding the method for evaluating film characteristics, surface roughness is expressed as center line average roughness Ra. Measurement method, DIN4768, cutoff value 0.25
mm. The friction coefficient is static friction coefficient μS, dynamic friction coefficient μ
K is measured and expressed according to ASTM-D-1894-63. Wear resistance was measured by contacting a tape-like film with a 90° wrapping angle to a stainless steel 10 mmφ fixed guide pin, at a load of 100 g, and at a speed of 2 m/sec.
Observe the scratches on the film surface after running it 1000 times and perform a relative evaluation. Excellent: No scratches Good: Few scratches Fair: Many scratches, but not practical: Severe scratches, not practical Wet tension is judged and displayed according to JIS K6768. The present invention will be explained below based on Examples. Example 1 Polyethylene terephthalate containing 0.05% by weight of silica particles with an average particle size of 1 μ ( ) or 3 μ ( ) was melted, extruded, and cooled to give a thickness of
Two types of sheets A in an unoriented amorphous state with a thickness of 150μ were prepared. Next, these sheets were first stretched 3.0 times in one direction at 80°C using a film stretcher manufactured by TM Long Co., Ltd. to produce a uniaxially stretched film B, and then the uniaxially stretched film B was stretched at right angles to the orientation direction. The film was stretched 3.3 times at 80°C, stretched on a frame, and heat-set at 200°C for 30 seconds in an oven to obtain a biaxially stretched film C. These sheets and films A, B, and C were coated with the following liquid on one side, dried, and heat-treated at 200° C. for 30 seconds. The coating amount at this time was adjusted so that the solid content was 10 mg/m ² . Silicone emulsion Softner 302 (manufactured by Matsumoto Yushi) 0.4wt% Silane coupling agent SH0040 (manufactured by Toray Silicone) 0.01wt% Nonionic surfactant NS210 (manufactured by NOF)
0.10Wt% The properties of the obtained film are as follows.

[Table] Example 2 In Example 1, crosslinkable silicone SR x 244 (Tore Silicone) was added to raw material I and film B.
20wt%, catalyst SR x 242AC 1wt%, silane coupling agent SH6020 (Toray Silicone) 10wt%,
Nonionic surfactant Pluronic L-44 (BASF)
A solution of 10 wt % and toluene as a solvent was applied so that the solid content was 60 mg/m ² , and after drying, a biaxially stretched film was obtained in the same manner as in Example 1. The properties of the obtained film are as follows.

[Table] Example 3 In Example 2, when no activator is added,
The wet tension was 92 dynes. Example 4 In Example 2, the slip μS on both sides was compared between the case where both sides of the film were coated and the case where one side was coated.

[Table] Examples 5 and 6, Comparative Examples 1 and 2 Same as Example 1, except that particles with an average particle size of 1μ were selected and the concentration of the silane coupling agent SH0040 in the coating liquid was changed as follows. In the same manner as in Example 1, a biaxially stretched polyester film having a film formed from a crosslinkable silicone and a silane coupling agent adhered thereto was obtained. Concentration of silane coupling agent in coating liquid Example 5: 0.006wt% 〃 6: 1.9wt% Comparative Example 1: 0.003wt% 〃 2: 2.2wt% The properties of the film thus obtained are shown in Table 4. Examples 7 and 8 A polyester biaxially stretched film with a film adhered thereto was obtained in the same manner as in Example 5, except that the amount of coating liquid applied in Example 5 was changed as follows. Coating amount of coating liquid (indicated by solid content) Example 7: 1.5 mg/m ² Example 8: 900 mg/m ² The properties of the film thus obtained are shown in Table 4. Comparative Example 3 A sheet of amorphous non-oriented polyethylene terephthalate with a thickness of 100 μm was coated with 1% silicone emulsion SH8800 manufactured by Torre Silicone and 0.5% silane.
% emulsion was applied as a solid content of 5mg/m ² and heated for 10 seconds with hot air at 110℃ and 9.6m/sec.
The polyester biaxially stretched film was stretched 3 times in the longitudinal direction and 3.2 times in the transverse direction to obtain a polyester biaxially stretched film to which the film was adhered. The properties of this film are shown in Table 4.

【table】

Claims (1)

[Claims] 1. A film formed from a crosslinkable silicone and a silane coupling agent and having a ratio of silicone to silicone of 1 to 0.01 to 5 of the silane coupling agent is adhered to at least one side of the base film. polyester film.