JP5220973B2 - Shading film - Google Patents

Description

  The present invention relates to a light-shielding film useful as a light-shielding member for various optical devices such as cameras, video cameras, copying machines, and developing machines.

Recently, many high-performance compact cameras with excellent portability are on the market for travel, leisure, and outdoor work. In addition, the number of individuals who shoot video has increased, and along with this, video cameras have become lighter and more compact, and recently they have been downsized to the extent that they can be placed in the palm of your hand.
As described above, with the downsizing and weight reduction of optical devices, particularly cameras and video cameras, parts constituting them are required to be downsized or lightened. Conventionally, metals have been used for light shielding members such as shutters and diaphragms, but synthetic resin films have been increasingly used with the reduction in size, weight, and cost. Under such circumstances, as a light-shielding film used in optical equipment, (1) a polyester film mixed with carbon black is roughened by sandblasting and further coated with an electron conductive type conductive agent (special (Kaihei 1-12503), (2) A synthetic resin film provided with a thermosetting resin or a room temperature curable resin containing carbon black and a lubricant on both sides (Japanese Patent Laid-Open No. 4-9802), (3) A synthetic resin film obtained by laminating a synthetic resin layer having surface matteness, conductivity and light shielding properties on at least one surface of a synthetic resin film (Japanese Patent Laid-Open No. 4-62048) is known.

  However, these conventional light shielding films are not always satisfactory from the viewpoint of light shielding properties and economical efficiency. For example, in the case of (1), in order to obtain a high light-shielding property, a large amount of carpon black must be mixed, which changes the mechanical and other physical properties of the film. Furthermore, since the surface is roughened by sandblasting, surface irregularities are easily crushed by rubbing between the films, and the film surface becomes glossy after long-term use. In addition, in the case of (2), since carbon black and a lubricant are contained in the thermosetting resin or the room temperature curable resin layer on the film, the surface tends to be glossy. Large carbon blacks and lubricants must be used. For this reason, there is a disadvantage that the light shielding property is lowered. Further, in the case of (3), since the light shielding layer is substantially composed of a resin, there is a drawback that the slipperiness becomes insufficient.

As described above, the conventional light-shielding film does not satisfy all of the light-shielding properties, slidability, conductivity, and surface matte properties.
Under such circumstances, we have previously invented a light-shielding film that is excellent in light-shielding property, sliding property, electrical conductivity, and surface matte property, and is suitable as a shutter or diaphragm for optical equipment (Japanese Patent Laid-Open No. 7-31904). Publication). However, in recent years, in addition to the reduction in size and weight, precision has been required, and along with this, flatness has become increasingly severe, especially in shutters for optical equipment. In other words, slight warpage causes light leakage and causes a reduction in shutter speed.

Mistakes the invention seeks to solve

  The bare title of the present invention is to provide a light-shielding film which is excellent in light-shielding properties, slidability, conductivity and surface matte properties, and suitable for shutters and diaphragms for optical devices having excellent flatness. To do.

Means for solving the problem

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. That is, according to this invention, the light shielding film shown below is provided.
(1) A light-shielding layer comprising a binder resin, a black fine powder having an average particle diameter of 1 μm or less, an organic filler having an average particle diameter of 0.5 to 10 μm, and a lubricant having an average particle diameter of 0.1 to 10 μm on at least one surface of the base film. And the binder resin is a thermoplastic polycarbonate urethane resin or a thermoplastic polyester resin having a Tg of 40 ° C. or higher and a softening point of 80 ° C. or higher.
(2) The light-shielding film according to (1), wherein the polyester resin is an aqueous polyester resin.
( 3 ) In the light shielding layer, the binder resin content is 25 to 65% by weight, the black fine powder content is 10 to 30% by weight, the organic filler content is 20 to 40% by weight, and the lubricant. The light shielding film as described in said (1) or (2) whose content is 5 to 15 weight%.
( 4 ) The light shielding film according to any one of (1) to (3), wherein the light shielding layer is provided on both surfaces of the substrate.

  As the base film used in the present invention, synthetic resin films such as polycarbonate, polyester, polystyrene, and polyimide are used, and polyester films are particularly preferable. The base film can be a transparent polyester film, a foamed polyester film, a synthetic resin film containing black pigment such as carbon black, or other pigments. In this case, the base film can be selected appropriately depending on the application. For example, a black resin-containing synthetic resin film can be used when high light shielding properties are required, and a transparent or foamed synthetic resin film can be used otherwise. The thickness of the base film varies depending on the purpose of use and application field, but is usually selected in the range of 12 to 250 μm, preferably 25 to 200 μm. Further, the base film can be subjected to anchor treatment or corona treatment as necessary. Thereby, the adhesiveness of a synthetic resin layer and a base film improves.

Examples of the binder resin used for the light shielding layer in the present invention include polyurethane resin, poly (meth) acrylic acid resin, polyester resin, polyvinyl acetate resin, polyvinyl chloride, polybutyral resin, cellulose resin, polystyrene / polybutadiene resin. These may be used, and one or more of these may be mixed and used.
In the binder resin used in the present invention, the Tg (glass transition temperature) is 40 ° C. or higher, preferably 45 ° C. or higher, and the upper limit is usually about 150 ° C. Its softening point temperature is 80 ° C. or higher, preferably 90 ° C. or higher, and its upper limit is usually about 300 ° C.

In the present invention, a polycarbonate urethane resin is preferably used as the binder resin. According to the present inventors, when this was used as a binder resin, it was found that a light-shielding film having excellent hardness and scratch resistance and excellent flatness was obtained.
The polycarbonate-based urethane resin can be easily obtained by reacting a carbonate polyol, a polyisocyanate compound and a chain extender by a conventionally known production method.
Polycarbonate polyol is synthesized by, for example, phosgenation of polyol, transesterification with diphenyl carbonate, condensation polymerization of dibasic acid and glycols, or the like. Examples include products obtained by reacting 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol or tetraethylene glycol with a diaryl carbonate such as diphenyl carbonate or with phosgene. . With respect to the condensation polymerization method of dibasic acid and glycols, for example, a method in which a dihydric phenol as a dibasic acid and a cyclic diol such as glycol carbonate as a glycol are subjected to condensation polymerization.
Examples of the polyisocyanate compound include aromatic, aliphatic and alicyclic polyisocyanate compounds. For example, 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 1,5-naphthylene diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, 1,3-xylylene diisocyanate, 1,4-tetramethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 1,10-decanmethylene diisocyanate, 1,3, or 1,4-cyclohex Examples thereof include silylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and 1,3-isocyanomethylcyclohexane.
As the chain extender, a compound containing at least two functional groups containing an active hydrogen atom reactive with an isocyanate group can be used. For example, water, ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,5-hexanediol, ethylenediamine, 1,2-propylenediamide, triethylenediamine, decamethylenediamine, isophoronediamine, m-xylylenediamine , Dimethylhydrazine, dicarboxylic acid, hydrogen sulfide and the like.
In the present invention, those having a Tg of 40 to 150 ° C., preferably 45 to 140 ° C. and a softening point temperature of 80 to 300 ° C., preferably 85 to 290 ° C., can be preferably used.

  The Tg is measured by differential thermal analysis (DTA) or differential scanning calorimetry (DSC), and the softening point temperature is measured by a penetration method or ring and ball method.

  The content of the binder resin in the light-shielding layer is 25 to 65% by weight, preferably 30 to 60% by weight, based on the total weight of the binder resin, carbon black, organic filler and lubricant. Adhesiveness between the material film and the light shielding layer is lowered, and if it is more than this range, it becomes difficult to balance light shielding properties, slidability, conductivity and surface matte properties.

  As the black fine powder used in the present invention, various conventionally known powders, for example, inorganic pigments such as carbon black and titanium black, and organic pigments such as aniline black are used, and the average particle diameter is preferably 1 μm or less, preferably Is 0.5 μm or less. The lower limit is usually about 0.01 μm. When the average particle size is larger than this range, the surface matte property is sufficient, but the light shielding property is lowered, which is not preferable. The content of the black fine powder is 10 to 30% by weight, preferably 15 to 25% by weight in the light shielding layer. When the content is less than this range, the light shielding property and conductivity are lowered. It is inferior in mattness and is expensive.

  Examples of the organic filler used in the present invention include various synthetic resin particles such as melamine resin, benzoguanamine resin, benzoguanamine / melamine / formalin condensate, acrylic resin, urethane resin, and styrene resin. Mixtures of seeds can also be used. The shape of the organic filler may be either a spherical product or a pulverized product, but the use of the spherical product is preferable because the static friction coefficient is lowered and the slidability is improved. The content of the organic filler is 20 to 40% by weight, preferably 25 to 35% by weight in the light shielding layer, and if it deviates from this range, the matte surface and slidability of the surface are lowered. The average particle diameter of the organic filler is 0.5 to 10 μm, preferably 1 to 8 μm. If it is larger than this range, the light shielding property is lowered, and if it is smaller, the matte effect on the film surface becomes insufficient. These organic fillers may be used alone or in combination of two or more. Furthermore, these organic fillers may be colored black or dark.

  As the lubricant used in the present invention, various conventionally known lubricants, for example, hydrocarbon lubricants such as polyethylene, fatty acid lubricants such as stearic acid, alcohol lubricants such as stearyl alcohol, solid lubricants such as molybdenum disulfide, Examples include silicon-based resin particles, fluorine-containing resin particles, crosslinked polymethyl methacrylate particles, and crosslinked polystyrene particles. The shape of the lubricant may or may not be spherical, but the spherical shape is preferred from the viewpoint of slidability and surface matteness. The content of the lubricant is 5 to 15% by weight, preferably 7 to 13% by weight in the light-shielding layer, and if it is out of this range, the slidability and the surface matte effect are lowered. The average particle size of the lubricant is 0.1 to 10 μm, preferably 0.15 to 7 μm. If the average particle size is larger than this range, the sliding effect is reduced, and if the average particle size is smaller than this range, , The matte surface of the film becomes inferior.

  The light shielding film of this invention can be obtained by coating the coating liquid containing binder resin, a black fine powder, an organic filler, and a lubrication agent on the single side | surface or both surfaces of a base film. The solvent of the coating solution can be water, an organic solvent, a mixture of water and an organic solvent, or the like. Further, the binder resin may be dissolved or dispersed in a solvent.

  In the light-shielding film of the present invention, the light-shielding layer may be a single layer, or may be composed of two or more layers. For example, a light shielding layer comprising two layers can be formed by coating a coating solution containing a binder resin and a lubricant on a layer comprising a binder resin, black fine powder and an organic filler. In this case, since the outermost layer is a layer containing a lubricant, higher slidability can be obtained. In addition, a light-shielding layer consisting of three layers is formed by forming a layer made of a binder resin and black fine powder on a layer made of a binder resin and an organic filler, and further forming a layer made of a binder resin and a lubricant thereon. Can be formed. Even when the light shielding layer is composed of two or more layers, the ratio of each component contained in the entire light shielding layer is the same as the above range. The thickness of the light-shielding layer varies depending on the use state of the light-shielding film, but is generally 2 to 30 μm. When used as a camera shutter, it is 3 to 25 μm, preferably 10 to 20 μm.

  Next, the present invention will be described in more detail with reference to examples. In the following, all parts and% are based on weight.

Example 1
A coating liquid having the following formulation is provided on both sides of a carbon black-containing polyester film having a thickness of 50 μm via an undercoat layer (thickness: 1 μm) made of a saturated polyester resin (trade name “Byron”, manufactured by Toyobo Co., Ltd.). And dried at 100 ° C. for 2 minutes to obtain a light-shielding film having a thickness of 14 μm. In addition, the thickness of the whole light shielding film was 80 micrometers.
(Coating solution)
Polycarbonate urethane resin (Tg62 ℃, softening point 183 ℃)
(RU-41-083; made by Stahl) 35.0 parts Carbon black (average particle size 0.3 μm)
(SP Black AS-1192; manufactured by Gokoku Color Co., Ltd.) 20.0 parts cross-linked polymethyl methacrylate resin filler (average particle size 5 μm)
(Techpolymer MBX-5; manufactured by Sekisui Plastics Co., Ltd.) 35.0 parts Crystalline polyethylene wax (average particle size 0.15 μm)
(High Tech S-8512; manufactured by Toho Chemical Industry Co., Ltd.) 10.0 parts

Example 2
The light shielding film was obtained similarly except having changed the polycarbonate-type urethane resin of Example 1 into the following material.
Saturated copolymer polyester resin (Tg65 ℃, softening point 150 ℃)
(Aron Melt PES-2655A30; manufactured by Toa Gosei Co., Ltd.)

Example 3
The light shielding film was obtained similarly except having changed the polycarbonate-type urethane resin of Example 1 into the following material.
Polyester urethane resin (Tg49 ℃, softening point 112 ℃)
(Hydran AP-40 (F); manufactured by Dainippon Ink & Chemicals, Inc.)

Comparative Example 1
The light shielding film was obtained similarly except having changed the polycarbonate-type urethane resin of Example 1 into the following material.
Thermosetting acrylic resin (Mobile 710; manufactured by Clariant Polymer Co., Ltd.)

Comparative Example 2
The light shielding film was obtained similarly except having changed the polycarbonate-type urethane resin of Example 1 into the following material.
Polycarbonate urethane resin (Tg-16 ° C, heat melting temperature 140 ° C)
(Superflex 460S; Daiichi Kogyo Seiyaku Co., Ltd.)

Comparative Example 3
A light shielding film was obtained by sandblasting both surfaces of a carbon black-containing polyester film having a thickness of 75 μm.

  Each of the light shielding films described above was tested by the following method, and the results are shown in Table 1.

Test 1 (light shielding)
A light of 100,000 lux was applied to the light shielding film, and a black and white film with an exposure index of ISO 3200 was placed behind the light shielding film to examine whether the black and white film was exposed. Evaluation was carried out with ◯ ×.
Test 2 (conductivity)
The surface resistivity of the light shielding film was measured based on JISK-6911.
Test 3 (surface mattness)
The glossiness of the light shielding film was measured based on JIS Z-8741.

Test 4 (slidability)
The static friction coefficient of the light shielding film was measured based on ASTM D-1984.
Test 5 (flatness)
The light-shielding film was cut into 50 mm × 50 mm, placed on a flat table, and the heights (warping amounts) of the four corners of the film were measured with a thickness gauge, and the largest value was recorded. Evaluation was performed in five stages as follows.
5: 0.2 mm or less 4: 0.3-0.4 mm
3: 0.5-0.6mm
2: 0.7-0.8mm
1: 0.9 mm or more test 6 (blocking resistance)
Two sheets of light-shielding film cut to 50mm x 50mm are stacked, and a weight is applied to a rectangular parallelepiped with a bottom of 50mm x 50mm and a weight of 500g. After blocking for 24 hours in a constant temperature bath at 40 ° C and 85% RH It was measured. Evaluation was carried out with ◯ ×, and those with blocking were marked with × and those without blacking were marked with ○.

Effect of the invention

  The light-shielding film of the present invention is a shutter for optical equipment having a small amount of warpage and excellent flatness, as well as a well-balanced light-shielding property, conductivity, matte surface, slidability and blocking resistance, It is suitable as a light shielding member for optical devices such as a diaphragm. Therefore, it can sufficiently cope with optical devices that require higher precision. In the light-shielding film of the present invention, the degree of light shielding can be easily changed by adjusting the content of carbon black in the light-shielding layer, and can correspond to various kinds of light-shielding materials for optical devices.

Claims (4)

Provided on at least one surface of the base film is a light shielding layer comprising a binder resin, a black fine powder having an average particle size of 1 μm or less, an organic filler having an average particle size of 0.5 to 10 μm, and a lubricant having an average particle size of 0.1 to 10 μm, The light-shielding film is characterized in that the binder resin is a thermoplastic polycarbonate urethane resin or a thermoplastic polyester resin having a Tg of 40 ° C. or higher and a softening point of 80 ° C. or higher.
The light-shielding film according to claim 1, wherein the polyester resin is an aqueous polyester resin.
In the light shielding layer, the binder resin content is 25 to 65% by weight, the black fine powder content is 10 to 30% by weight, the organic filler content is 20 to 40% by weight, and the lubricant content is It is 5 to 15 weight%, The light shielding film of Claim 1 or 2 .
The light shielding film according to any one of claims 1 to 3, wherein the light shielding layer is provided on both surfaces of the substrate.