JP2003029314A - Light shielding film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light shielding film which is superior in light shielding function, sliding function, conductivity, matting effect and is most appropriate for a shutter or a diaphragm for an optical instrument superior in planeness. SOLUTION: The light shielding film is characterized in that it is provided with a light shielding layer consisting of a binder resin, black colored fine powders with an average particle diameter of <=1 μm, organic filler with an average particle diameter of 0.5 to 10 μm and lubricant with an average particle diameter of 0.1 to 10 μm on at least one side of the base material film, and the binder resin is a thermoplastic resin with Tg >=40 deg.C and softening point of >=80 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-shielding film useful as a light-shielding member for various optical devices such as cameras, video cameras, copiers and developing machines.

[0002]

2. Description of the Related Art Recently, a lot of high performance compact cameras having excellent portability have been put on the market for traveling, leisure and working outdoors. In addition, personal video shooting has increased, and along with this, video cameras have become lighter and more compact, and recently, they have been downsized to the size of a palm. As described above, as optical devices, particularly cameras and video cameras, are made smaller and lighter, the components that make them up are also required to be smaller or lighter.
Conventionally, metal is used for light-shielding members such as shutters and diaphragms, but with the reduction in size, weight and cost,
Synthetic resin films are increasingly used. In such a case, as a light-shielding film used in optical equipment, a polyester film mixed with carbon black is roughened by sandblasting and further coated with an electron conductive type conductive agent (JP-A-1- 12503), a thermosetting resin or a room temperature curable resin containing carbon black and a lubricant provided on both sides of a synthetic resin film (JP-A-4-9802), and at least one surface of the synthetic resin film has a matte surface. There is known one in which a synthetic resin layer having both properties, conductivity and light-shielding property is laminated (JP-A-4-62048).

However, these conventional light-shielding films are not always sufficiently satisfactory in terms of their light-shielding properties and economical efficiency. For example, in order to obtain a high light-shielding property, a large amount of carbon black must be mixed in, so that the mechanical and other physical properties of the film are changed. Further, since the surface is roughened by sandblasting, the unevenness of the surface is easily crushed due to the rubbing of the films, and the film surface becomes glossy after long-term use. In addition, in the case of the one, since carbon black and a lubricant are contained in the thermosetting resin or the room temperature curable resin layer on the film, gloss is likely to be generated on the surface, and in order to reduce the gloss of the surface, carbon having a large particle size is used. Black and lubricant must be used. Therefore, there arises a drawback that the light-shielding property is lowered. Further, in the case of the above, since the light-shielding layer is substantially composed of resin, there is a drawback that the slipperiness is insufficient.

As described above, the conventional light-shielding film does not satisfy all of the light-shielding property, the slidability, the conductivity and the matte surface property. In such a situation, we
A light-shielding film, which has excellent light-shielding properties, slidability, conductivity, and matte surface properties, and which is suitable as a shutter or aperture for optical equipment, was previously invented (JP-A-7-319004). However, in recent years, in addition to miniaturization and weight reduction, precision has been required, and accordingly, flatness has become more severe especially in shutters for optical devices. That is, a slight warp causes light leakage and a decrease in shutter speed.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a light-shielding material which is excellent in light-shielding properties, slidability, conductivity, and matte surface properties, and is also suitable as a shutter or diaphragm for optical equipment having excellent flatness. Providing a film is its bare title.

[0006]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, according to the present invention, the following light-shielding film is provided. (1) Binder resin, black fine powder having an average particle size of 1 μm or less, and an average particle size of 0.5 on at least one surface of the base film.
-10 μm organic filler and average particle size 0.1-10 μm
A light-shielding film comprising a light-shielding layer made of a lubricant of m, and the binder resin being a thermoplastic resin having a Tg of 40 ° C. or higher and a softening point of 80 ° C. or higher. (2) The content of the binder resin in the light shielding layer is 25 to
65% by weight, the content of the black fine powder is 10 to 30% by weight, the content of the organic filler is 20 to 40% by weight, and the content of the lubricant is 5 to 15% by weight. . (3) The light-shielding film according to (1) or (2), wherein the binder resin is a thermoplastic polycarbonate-based urethane resin. (4) The above-mentioned (1), in which the light-shielding layer is provided on both surfaces of the substrate.
The light-shielding film according to any one of to (4).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As the base film used in the present invention, synthetic resin films such as polycarbonate, polyester, polystyrene and polyimide are used.
A polyester film is particularly preferable. In addition to the transparent base film, a foamed polyester film or a synthetic resin film containing a black pigment such as carbon black or another pigment can be used. In this case, the base film can be selected appropriately depending on its use. For example, a synthetic resin film containing a black pigment can be used when high light-shielding property is 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 field of use, but is usually 12 to 250 μm,
It is preferably selected in the range of 25 to 200 μm. Also,
The base film may be subjected to anchor treatment or corona treatment, if necessary. This improves the adhesiveness between the synthetic resin layer and the base film.

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

In the present invention, it is preferable to use a polycarbonate urethane resin as the binder resin. The present inventors have found that when this is used as a binder resin, a light-shielding film having excellent hardness and scratch resistance and excellent planarity can be 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 method with diphenyl carbonate, condensation polymerization method 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. . Regarding the condensation polymerization method of dibasic acid and glycols, for example, dibasic acid is
Examples thereof include polyhydric phenols obtained by condensation-polymerizing cyclic diols such as glycol carbonate as glycols. 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-decane methylene diisocyanate, 1,3, or 1,4-cyclohexylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1, 3-isocyanomethyl cyclohexane etc. are mentioned. 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, Examples thereof include dicarboxylic acid and hydrogen sulfide. In the case of the present invention, its Tg is 40 to 150 ° C., preferably 45 to 140 ° C., and its softening point temperature is 80 to
Those having a temperature of 300 ° C, preferably 85 to 290 ° C can be preferably used.

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

The content of the binder resin in the light-shielding layer is 25 to 65% by weight, preferably 3 based on the total weight of the binder resin, carbon black, organic filler and lubricant.
If it is less than this range, the adhesiveness between the base film and the light-shielding layer will be reduced, and if it is more than this range, the balance of light-shielding property, slidability, conductivity and surface matteness will be achieved. Will be difficult to obtain.

As the black fine powder used in the present invention, various conventionally known ones, for example, inorganic pigments such as carbon black and titanium black, organic pigments such as aniline black and the like are used, and the average particle diameter is 1 μm. The following is preferably 0.5 μm or less. The lower limit is usually 0.0
It is about 1 μm. When the average particle size is larger than this range, the surface matte property is sufficient, but the light-shielding property is deteriorated, 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. If it is less than this range, the light-shielding property and conductivity are lowered, and if it is more than this range, the surface is reduced. It is inferior in mattness and costly.

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. It is also possible to use one kind or a mixture of two kinds. The shape of the organic filler may be a spherical product or a crushed 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 in the light-shielding layer is 20 to 40% by weight, preferably 25 to 35% by weight. If the content of the organic filler deviates from this range, the matteness and slidability of the surface deteriorate. The average particle size of the organic filler is from 0.5 to 10 μm, preferably from 1 to 8 μm. When the average particle size is larger than this range, the light-shielding property is deteriorated, and when it is smaller, the matte effect on the film surface becomes insufficient. In addition, these organic fillers may be used alone or
More than one type may be used. 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, solids such as molybdenum disulfide, etc. Lubricants, silicone resin particles, fluorine-containing resin particles, crosslinked polymethylmethacrylate particles, crosslinked polystyrene particles and the like can be mentioned. The lubricant may or may not have a spherical shape, but a spherical shape is preferable in terms of slidability and surface matteness. The content of the lubricant in the light-shielding layer is 5 to 15% by weight, preferably 7 to 13% by weight, and if it deviates from this range, the slidability and the surface matting effect are deteriorated. The average particle size of the lubricant is 0.1 to 10 μm, preferably 0.15 to 7 μm. When the average particle size is larger than this range, the sliding effect is reduced, and when the average particle size is smaller than this range. , The surface of the film becomes less matte.

The light-shielding film of the present invention can be obtained by coating one or both surfaces of a base film with a coating solution containing a binder resin, black fine powder, an organic filler and a lubricant. The solvent of the coating liquid is water or organic solvent,
It can be a mixture of water and an organic solvent or the like. Also,
The binder resin may be dissolved or dispersed in the 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 composed of two layers can be formed by coating a coating solution containing a binder resin and a lubricant on a layer composed of 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. Further, a light-shielding layer consisting of three layers is formed by forming a layer consisting of a binder resin and black fine powder on a layer consisting of a binder resin and an organic filler, and further forming a layer consisting 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. Although the thickness of the light-shielding layer varies depending on the use condition of the light-shielding film, it is generally 2 to 30 μm, and when used as a camera shutter, 3 to 25 μm,
It is preferably 10 to 20 μm.

[0017]

EXAMPLES The present invention will be described in more detail with reference to examples. All parts and% shown below are based on weight.

Example 1 An undercoat layer made of a saturated polyester resin (trade name "Byron", manufactured by Toyobo Co., Ltd.) on both sides of a carbon black-containing polyester film having a thickness of 50 μm (thickness:
1 μm) and apply the coating solution of the following formulation at 100 ° C
And dried for 2 minutes to obtain a light-shielding film having a thickness of 14 μm. In addition,
The thickness of the entire light-shielding film was 80 μm. (Coating liquid) Polycarbonate-based urethane resin (Tg 62 ° C, softening point 183 ° C) (RU-41-083; manufactured by Stahl) 35.0 parts Carbon black (average particle size 0.3 µm) (SP black AS-1192; Mikuni dye) 20.0 parts Crosslinked polymethylmethacrylate resin filler (average particle size 5 μm) (Techpolymer MBX-5; Sekisui Plastics Co., Ltd.) 35.0 parts Crystalline polyethylene wax (average particle size 0 .15 μm) (Hitec S-8512; manufactured by Toho Chemical Industry Co., Ltd.) 10.0 parts

Example 2 A light-shielding film was obtained in the same manner except that the polycarbonate urethane resin of Example 1 was changed to the following materials. Saturated copolyester resin (Tg 65 ° C, softening point 15
(0 ° C) (Aron melt PES-2655A30; manufactured by Toagosei Co., Ltd.)

Example 3 A light-shielding film was obtained in the same manner except that the polycarbonate urethane resin of Example 1 was changed to the following materials. Polyester urethane resin (Tg 49 ° C, softening point 112
C) (Hydran AP-40 (F); Dainippon Ink and Chemicals, Inc.)

Comparative Example 1 A light-shielding film was obtained in the same manner except that the polycarbonate urethane resin of Example 1 was changed to the following materials. Thermosetting acrylic resin (Movinyl 710; manufactured by Clariant Polymer Co., Ltd.)

Comparative Example 2 A light-shielding film was obtained in the same manner except that the polycarbonate-based urethane resin of Example 1 was changed to the following materials. 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 sides of a carbon black-containing polyester film having a thickness of 75 μm.

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

Test 1 (Light-shielding property) A light-shielding film was irradiated with light of 100,000 lux, and a black-and-white film having an exposure index ISO3200 was placed behind it to examine whether or not the black-and-white film was exposed. The evaluation was carried out by ◯ ×, and those exposed to light were evaluated as ×, and those not exposed at all were evaluated as ◯. Test 2 (conductivity) The surface resistivity of the light-shielding film was measured based on JISK-6911. Test 3 (Surface Matte Property) The glossiness of the light-shielding film was measured according to JIS Z-8741.

Test 4 (sliding property) The static friction coefficient of the light-shielding film was measured according to ASTM D-1984. Test 5 (flatness) The light-shielding film was cut into 50 mm × 50 mm, placed on a flat stand, and the heights (warpage amounts) of the four corners of the film were measured with a sykness gauge, and the largest value was recorded. The evaluation was carried out in five stages as follows. 5: 0.2 mm or less 4: 0.3 to 0.4 mm 3: 0.5 to 0.6 mm 2: 0.7 to 0.8 mm 1: 0.9 mm or more Test 6 (blocking resistance) 50 mm x 50 mm Two cut light-shielding films are stacked,
A rectangular parallelepiped having a bottom surface of 50 mm × 50 mm and a weight of 500 g was placed as a weight, and the presence or absence of blocking was measured after standing in a thermostat at 40 ° C. and 85% RH for 24 hours. The evaluation was carried out with ◯, and those with blocking were marked with ×, and those without blacking were marked with ◯.

[0027]

[Table 1]

[0028]

The light-shielding film of the present invention has a well-balanced light-shielding property, conductivity, matte surface, slidability and blocking resistance, as well as a small amount of warpage and excellent flatness. It is suitable as a light shielding member for optical devices such as shutters and diaphragms for optical devices. Therefore, it is possible to sufficiently deal with an optical device that requires higher precision. Further, 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 it can be applied to various light-shielding materials for optical devices.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09D 201/00 C09D 201/00 // C08L 67:02 C08L 67:02 (72) Inventor Nahiko Kiryu Tokyo 4-11-2 Ginza, Chuo-ku Somer Co., Ltd. F term (reference) 2H080 AA10 AA13 AA15 4F006 AA35 AB24 AB37 AB72 CA05 DA04 4F100 AA37A AH00B AK01B AK04B AK25B AK41A AK41C AK45B AK51B CC00B BA01B10B ABAB10B ABAB10BBA10B ABAB07B07B07B07 JA05B JB16B JL10B JN02 YY00B 4J038 BA021 CA041 CB022 CC022 CC041 CD021 CE071 CF021 CG001 CG002 DA152 DD001 DG002 DG121 DL002 HA026 HA356 JA22 JA38 JB31 KA08 KA09 KA12 KA20 MA14 NA01 NA08 NA08 PA18 P18 PB

Claims (4)

[Claims] 1. 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 an average particle size of 0.1 on at least one surface of a substrate film.
A light-shielding film, characterized in that a light-shielding layer made of a lubricant having a thickness of 10 μm is provided, and the binder resin is a thermoplastic resin having a Tg of 40 ° C. or higher and a softening point of 80 ° C. or higher. 2. The content of the binder resin in the light shielding layer is 25 to 65% by weight, and the content of the black fine powder is 10 to 3
0% by weight, the content of the organic filler is 20 to 40% by weight
The light-shielding film according to claim 1, wherein the lubricant content is 5 to 15% by weight. 3. The light-shielding film according to claim 1, wherein the binder resin is a thermoplastic polycarbonate-based urethane resin. 4. The light-shielding film according to claim 1, wherein the light-shielding layer is provided on both sides of a base material.