JP2003238820A - Antistatic resin material for optical instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin material for an optical instrument excellent in an antistatic property. <P>SOLUTION: The antistatic resin material for an optical instrument comprises a composition obtained by adding 0.1-20 wt.% of a carbon nanotube to a thermoplastic resin. The carbon nanotube has, for instance, a cylindrical shape having a diameter of 0.01 μm and a length of 1-10 μm and comprises 100% of a carbon atom. It does not generally exist alone in a cylindrical shape but exists in an entangled state, When the amount of the carbon nanotube to be added is 0.1 wt.% or less, the surface resistance of a resin material is not reduced to 10<SP>11</SP>Ω or less and thus the desired antistatic property cannot be attained. When the amount of the carbon nanotube to be added is more than 20 wt.%, on the other hand, a problem occurs in relation to moldability of a resin material, etc. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an antistatic resin material for optical equipment. More specifically, the present invention relates to an antistatic resin material for optical equipment used for molding parts such as a shutter base plate, a shutter blade retainer, and an intermediate plate that are required to have antistatic performance incorporated in a camera or the like.

[0002]

2. Description of the Related Art A shutter device for a camera is assembled by using a main plate. The shutter blade is movably mounted on the main plate. If the driving force is strong, it is not easily affected by the charging of the ground plane. However, when the driving force of the shutter is weakened due to the power saving in recent years, the shutter blades come into close contact with each other even with a small amount of charging due to friction, and the shutter becomes inoperable. Therefore, conventionally, a solid lubricating film having an antistatic property has been formed on the surface of a base plate made of a plastic molded product to prevent close contact with the shutter blades. Alternatively, conductive carbon black particles or carbon fibers may be mixed into the molding resin material itself.

[0003]

When forming a lubricating coating film having an antistatic property on the surface of a plastic base plate, it was usually coated by spraying. However, a large amount of paint and solvent was released to the environment due to overspray during painting. Further, when carbon fiber is mixed in the molding material, the surface layer of the shutter base plate is basically covered with the molding resin, so that the shutter blades are electrically charged here and the shutter blades adhere to each other. Further, when a large amount of carbon black is kneaded into the molding resin in order to lower the electric resistance, the fluidity of the resin deteriorates, the moldability is impaired, and the strength decreases.

[0004]

[Means for Solving the Problems] The above-mentioned conventional technology section
In view of the problem, the present invention provides a belt for an optical device having excellent antistatic performance.
An object is to provide an antistatic resin material. Purpose
The following measures were taken to achieve the. That is, according to the present invention
Antistatic resin materials for optical equipment are
Add 0.1 to 20% by weight of carbon nanotubes,
Surface resistance is 10 ¹¹Having antistatic performance below Ω
Characterize. Preferably, the thermoplastic resin is PC
(Polycarbonate Polycarbonate tree
Fat), PBT (Polybutyrene Terep)
hthalate polybutylene terephthalate), P
ET (Polyethylene Terephtha)
late polyethylene terephthalate), ABS (A
crynitrite-butadiene-st
yrene Resin ABS resin), PA (Pol
amide polyamide resin [nylon resin]), P
S (Polystyrene polystyrene), PPS
(Poly Phenylene Sulfide R
esin polyphenylene sulfide resin), LCP
(Liquid Crystal Polymer liquid crystal
Polymer), PEI (Poly Ether Imid)
e Polyetherimide), PEEK (Poly (et
her-ether-ketone)
-Terketone resin), PMMA (Methacrylic)
c Resins Methacrylic resin [acrylic resin
Fat]), PPE (Poly Penylene-Eth)
er Resins polyphenylene ether resin),
POM (Polyacetal Resins)
Cetal resin) or these alloys
It is characterized by Moreover, carbon black is added to the resin.
0.1 to 10% by weight of antistatic property and light shielding property
It is characterized by increasing. Also, glass fiber or carbon fiber
Contains 1 to 30% by weight of reinforcing material made of fiber
Characterize things. In addition, PTFE (Poly Tetr)
a Fluoro ethylene polytetrafluoride
Selected from (Tylene), graphite and molybdenum disulfide.
The added lubricant was added at a rate of 1 to 30% by weight.
To collect.

The present invention also relates to a shutter base plate for mounting shutter blades for a camera, a blade retainer, an intermediate plate, or a molded article such as a lens barrel, a mirror box, or a camera body, which is averse to static electricity generation. It includes a component for optical equipment, which is characterized by being molded with an antistatic resin material.

[0006] According to the present invention, a small amount of carbon nanotubes that does not significantly change the impact resistance and fluidity of the resin, does not change itself even when placed under high temperature during molding, and does not tend to decompose the resin. By adding, it is possible to obtain a resin material for an optical device having an antistatic property. Carbon nanotubes are being applied and developed in various fields, and antistatic resin materials for optical devices to which carbon nanotubes are added are a part of that, and are the results of the present invention. In another field, for example, a thermal transfer sheet to which carbon nanotubes are added is disclosed in JP-A-9-11647. Also, a functional coating composition containing carbon nanotubes is disclosed in JP-A-2000-26.
760 publication. Further, Japanese Patent Laid-Open No. 2001-276446 discloses a manufacturing tool made of plastic mixed with carbon nanotubes.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a shutter base plate for a camera formed of an antistatic resin material for an optical device according to the present invention. As shown, the shutter device basically includes a pair of shutter blades 3 and 4 and an electromagnetic actuator 2 that drives the shutter blades 3 and 4. The shutter blades 3 and 4 are arranged on a base plate 1 having a lens opening (not shown), and are driven by an electromagnetic actuator 2 to open and close the lens opening. In this example, one shutter blade 3 rotates about a pin 3b planted in the base plate 1. The other shutter blade 4 rotates about a pin 4b similarly planted in the main plate 1. The pair of shutter blades 3 and 4 are housed in a blade chamber provided between the main plate 1 and the blade retainer 1v. Since the base plate 1 does not interfere with the opening / closing operation of the shutter blades 3 and 4, antistatic performance is required. or,
The blade retainer 1v is also preferably required to have antistatic performance. Therefore, when the base plate 1, the blade retainer 1v, etc. are made of a plastic molded product, it is necessary to impart conductivity in advance.

The electromagnetic actuator 2 is mounted on the base plate 1 via a support 1u and is connected to the shutter blades 3 and 4 to open and close it. The electromagnetic actuator 2 is of a so-called moving magnet motor type, and includes a rotor 2a made of a permanent magnet and a rotor 2a wound around the rotor 2a in response to energization.
and a coil 8 for rotating a. The rotor 2a has a rotation shaft 1b, and can rotate bidirectionally between one end position and the other end position with the intermediate position interposed therebetween. The operating angle range is between the one end position and the other end position. An operating pin 2b is integrally attached to the rotor 2a by resin molding and engages with the shutter blades 3 and 4 to drive them. The coil 8 is wound around a coil frame 8a, and rotates the rotor 2a bidirectionally within an operating angle range according to energization. A yoke 7 is attached to the outer circumference of the coil frame 8a. If the driving force of the electromagnetic actuator 2 is suppressed to reduce the power consumption, the shutter blades 3 and 4 may come into close contact with each other even if the ground plate 1 is slightly charged.

The electromagnetic actuator 2 is provided with self-holding means for holding the rotor 2a at the intermediate position, one end position or the other end position when the coil 8 is not energized. This self-holding means includes an elastic member 5 that regulates the rotor 2a to an intermediate position by a mechanical elastic force, and one magnetic member 6 that holds the rotor 2a at one end position by a magnetic attractive force facing the rotor permanent magnet. And another magnetic member 6 that faces the rotor permanent magnet and holds the rotor 2a at the other end position by a magnetic attraction force. The elastic member 5 is composed of a coil spring having a pair of open ends 5i and 5j, and is provided with a blade retainer 1v.
It is attached to the fixed pin 1c formed on the. Between the pair of open ends 5i and 5j, a guide pin 1a similarly implanted in the blade retainer 1v is inserted. The operating pin 2b integrally formed with the rotor 2a has two open ends 5 of the elastic member 5.
It is clamped by i and 5j and regulated to an intermediate position. The shutter blades 3 and 4 are in a fully open position for opening a lens opening according to three points of the rotor 2a which can be held by the self-holding means,
It is possible to move to three positions, a fully closed position where the lens aperture is closed and a half open position where the lens aperture is partially opened.

FIG. 2 is a schematic plan view of the shutter blade shown in FIG. 1 viewed from the lower side of the main plate 1 (shutter blade side). The illustrated state is the rotor 2 of the electromagnetic actuator 2.
a is at an intermediate position, and the pair of shutter blades 3 and 4 connected to the operation pin 2b is a lens opening 1o formed in the base plate 1.
Is placed in a fully closed position. The rotor 2a made of a permanent magnet has an operating pin 2b integrated with resin. The operating pin 2b is engaged with operating long grooves 3a and 4a formed in the pair of shutter blades 3 and 4, respectively. As a result, the shutter blades 3 and 4 can be rotated about the rotation pin that is planted in the main plate 1. Further, the base plate 1 is provided with a fixing pin 1c for holding the elastic member 5 and a guide pin 1a for holding the state of the elastic member 5. As a result, both open ends 5i, 5j of the elastic member 5 are arranged at positions sandwiching the operating pin 2b of the rotor 2a. The illustrated electromagnetic actuator 2 includes a rotor 2a, a coil 8 and a yoke 7. By energizing the coil 8 in both forward and reverse directions, the rotor 2a can be rotated clockwise and counterclockwise within a predetermined operating angle range. As is clear from the above description, the base plate 1 is required to have high dimensional accuracy in order to mount various components, and has a relatively complicated shape. Therefore, when the base plate 1 is made of a plastic molded product, excellent moldability and smoothness are required in addition to the antistatic performance described above.

The antistatic resin material for optical equipment used for molding parts such as the base plate and blade retainer will be described below. The antistatic resin material for optical devices according to the present invention is basically a composition in which carbon nanotubes are added to a thermoplastic resin at a ratio of 0.1 to 20% by weight. The carbon nanotube has a diameter of, for example, 0.01 μm and a length of 1 to 10 μm.
It is a cylindrical material of m and consists of 100% carbon atoms. Usually, they are cylindrical and do not exist alone, but they are intertwined. When the amount of carbon nanotubes added is 0.1% by weight or less, the surface resistance of the resin material is 10%.
It does not fall below ¹¹ Ω, and the desired antistatic performance cannot be obtained. Also, the amount of carbon nanotubes added is 20
When it exceeds the weight%, problems occur in moldability of the resin material. Here, when the antistatic resin material according to the present invention is required to have a light-shielding property in applications such as optical devices, it is preferable to add 0.1 to 10% by weight of carbon black. If the carbon black content is 0.1% by weight or less, the light-shielding property may be insufficient. On the other hand, if the amount of carbon black added exceeds 10% by weight, problems such as moldability may occur.
At this time, if the channel black having excellent conductivity is used as the carbon black, the conductivity of the resin material for optical devices is further increased by the synergistic action with the carbon nanotubes. In addition, when the antistatic resin material according to the present invention is used for a shutter blade or the like which is required to travel at high speed, the strength may be insufficient. In that case, it is advisable to add 1 to 30% by weight of carbon fiber or glass fiber for reinforcement.
If the amount of fibers added is less than 1% by weight, the desired reinforcing effect cannot be obtained. On the other hand, if the fiber content exceeds 30% by weight,
Moldability may be inconvenient. Further, when the lubricity is insufficient depending on the application, 1 to 30% by weight of PTFE, graphite, molybdenum disulfide, etc. may be added to the antistatic resin material of the present invention to impart the lubricity.
If the addition amount is less than 1% by weight, the desired lubricating performance cannot be obtained. On the contrary, if the addition amount exceeds 30% by weight, the moldability and other properties of the resin may be adversely affected. As the thermoplastic resin, a polymer material having excellent moldability and high mechanical strength is generally selected. For example, PC, PBT, PE
T, ABS, PA, PS, PPS, LCP, PEI, P
It is possible to select EEK, PMMA, PPE, POM or alloys thereof.

FIG. 3 is a model diagram of a single carbon nanotube. Structurally, it has a cylindrical shape with eight graphite layers wound around a 0.005 μm hollow core. The diameter (D) is 0.01 μm and the length (L) is 1 to
It is 10 μm. Usually, single carbon nanotubes are aggregated to form a needle shape, a snake shape, an entangled shape, or the like.

Carbon nanotubes are cylindrical substances made of 100% carbon atoms. It is a very small crystal that has a structure in which one layer of graphite is rolled.
The carbon nanotube generation method includes an arc discharge method, a laser evaporation method, a CVD method and the like.

Carbon nanotubes have a large L / D ratio (aspect ratio) of 100 to 1000, and the theoretical strength of carbon nanotubes is estimated to be about 40 times that of carbon fibers. Therefore, it is expected as a filler that gives high strength and elastic modulus to the resin, but in reality it is a form in which the microcrystals of individual carbon nanotubes are firmly solidified, so the strength when compounded with the resin is improved. The effect cannot be expected so much. However, when carbon nanotubes are added to plastic as a conductive filler as in the present invention, excellent antistatic performance can be obtained. Hereinafter, a description will be added regarding this point.

As carbon-based conductive fillers, carbon black, graphite, carbon fibers and the like have been conventionally used in addition to carbon nanotubes. Among these, carbon nanotubes have the highest conductivity, and the electrical resistivity is 10 ⁻⁴ ohm-cm. The resistivity of carbon fiber is 10
^-3 ohm-cm, electric resistivity of graphite is 10 ^-2 ohm-c
m, the electric resistivity of carbon black is 10 ⁶ to 10 ^-2 o
hm-cm. For example, when carbon nanotubes are blended with a polycarbonate resin, the volume resistance value is about 1/3 to 1/4 that of the case where carbon fibers are blended, and the same level of conductivity is obtained. The reason for this is that the nanotubes themselves have excellent electrical conductivity, that they have a high aspect ratio, so they easily form a network in the resin, and they are extremely fine and have a low bulk density (100 g / 1000).
cc) The number per unit weight is large and the like. Since a predetermined conductivity can be obtained by adding a small amount, there is an advantage that cost increase is suppressed and other characteristics of the resin matrix itself, such as impact resistance and fluidity, are not significantly impaired.

In optical equipment applications, if the conductive filler falls off from the surface of the conductive resin molded product due to friction or the like,
In some cases it causes serious problems. Due to its fineness, carbon nanotubes have almost no "float", have a very clean surface state, and have a high strength and elastic modulus, so there is little falling off due to damage.

The carbon nanotube itself is made of pure carbon, and unlike carbon black or the like, contains almost no impurities. In addition, since it does not change even if it is placed under high temperature during molding or use, and it does not tend to decompose the resin, conductive compounds containing nanotubes are used for optical parts that do not like the gas generated from molded products. Suitable for

In particular, a resin material in which carbon nanotubes are mixed with a polycarbonate resin can be used to manufacture an antistatic optical component that is precisely molded while controlling the surface resistance value. Such an optical molded part exhibits excellent conductivity while maintaining the heat resistance and toughness (tensile elongation) inherent to the polycarbonate resin. The surface resistance value of the molded product can be controlled in the range of 10 ³ to 10 ¹¹ Ω without impairing the overall characteristics.

In a molded part in which carbon nanotubes are mixed with polycarbonate, fine carbon nanotubes are uniformly dispersed in a state of being entwined with each other, and the fiber diameter is 1/500 or less of that of general carbon fibers. Due to this dispersion form, the carbon nanotube-based composite resin has excellent antistatic performance over a wide range of surface resistance values, and even when the surface resistance value is higher than that of the carbon fiber-based composite resin, it is electrically charged. Is less likely to occur. This is because the conductive network of carbon nanotubes dispersed in the resin is extremely fine. In addition, since the carbon nanotubes are entangled and dispersed, and the exposure to the surface of the molded product is small, no particles are generated due to the dropping of the filler. Generation of dust is 1/10 or less compared to conventional carbon black and carbon fiber-based composite resin, which is equivalent to PC (polycarbonate) resin with no filler added.

FIG. 4 is a schematic plan view showing another example of the shutter base plate formed by using the above-mentioned conductive plastic material. This example is a focal plane shutter, and a rectangular opening 1 is formed at the center of the shutter base plate 11.
2 (indicated by a chain line) is provided. In the rest state, the four leading blades 10 partially overlap with each other to shield the shutter opening 12. Although not shown, a rear blade group is arranged below the front blade group in an overlapping manner. The blade presser 14 restricts unnecessary movement of the tip of each shutter blade. This blade retainer 14 can also be molded with the resin material according to the present invention. A pair of arms 15 and 16 are rotatably supported by the left end portion of the main plate 11 so as to be parallel to each other. Each leading blade 10 is locked to a pair of arms 15 and 16 at its tip. The arms 15 and 16 can also be molded from the resin material according to the present invention. Similarly, the rear blade group is also locked by a pair of arms (not shown). Slot 1 in main arm 15
7 is provided, and the elongated hole 1 associated with the rotation of the main arm 15 is provided.
A long groove 18 is provided in the shutter base plate 11 along the movement locus of 7. Although not shown, the slot 17 has a slot 1
A drive pin passing through the main plate 11 via 8 is engaged. When a shutter release button (not shown) is pressed, the drive pin moves upward by the biasing force applied along the long groove 18 provided in the shutter base plate 11. Along with this, the main arm 15 engaged with the drive pin in the slot 17
And the sub arm 16 interlocked with this rotates upward. Due to this rotation, the leading blade 10 runs vertically upwards to open the opening 12
To open. Then, a rear blade group (not shown) runs vertically to block the opening 12 and the exposure is completed.

Needless to say, the antistatic resin material for optical devices according to the present invention can be applied not only to the above-mentioned shutter base plate but also to molding other optical device parts. For example, the invention can be applied to a blade holder, an intermediate plate, or a molded product such as a lens barrel, a mirror box, and a camera body, which is averse to static electricity.

Finally, an embodiment will be described. A shutter base plate was molded using a resin material obtained by adding 20% by weight of glass fiber, 0.5% by weight of carbon nanotubes and 3% by weight of carbon black to a polycarbonate (PC) resin. A lens shutter was assembled using this shutter base plate, and a durability test was performed for 50,000 shutter operations. As a result, the operation of the shutter blades was good. Further, the surface resistance value of the shutter base plate was 5 × 10 ⁷ Ω, and the light shielding property was sufficient. This shutter base plate was able to reduce the cost as compared with the conventional molded product to which antistatic coating was applied.

Subsequently, Comparative Example 1 will be described for reference. A base plate was molded from a polycarbonate resin containing 20% by weight of carbon fiber and 3% by weight of carbon black. A lens shutter was assembled using this base plate and a durability test was conducted. As a result, when the shutter operation was performed several tens of times, the operation stopped due to charging. The surface resistance of the shutter base plate is 1
× 10 ¹² Ω or more.

As Comparative Example 2, a shutter base plate was molded from a polycarbonate resin containing 20% by weight of glass fiber and 3% by weight of carbon black, and a coating film having an antistatic function was formed on the surface thereof. A lens shutter was assembled with this base plate, and a durability test was performed 50,000 times as in the example. As a result, the operation of the shutter blades was good. The surface resistance of the ground plane was 7 × 10 ⁶ Ω. However, since this shutter base plate has a conductive coating film formed, it has an environmental problem.

[0025]

As described above, according to the present invention,
A plastic shutter base plate, blade retainer, intermediate plate, etc. can be formed by using an antistatic resin material for optical devices containing 0.1 to 20% by weight of carbon nanotubes in a thermoplastic resin. . This allows
It was possible to abolish the conductive coating that was conventionally applied to the surface of plastic parts. Also, the cost of parts could be reduced by eliminating the conductive coating.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a shutter device incorporating a base plate molded using an antistatic resin material for optical devices according to the present invention.

FIG. 2 is a partial plan view of a shutter device incorporating a base plate molded using an antistatic resin material for an optical device according to the present invention.

FIG. 3 is a schematic view showing carbon nanotubes added to the antistatic resin material for optical devices according to the present invention.

FIG. 4 is a plan view of another shutter device.

[Explanation of symbols]

1 ... Main plate, 11 ... Main plate

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C10M 103/02 C10M 103/02 Z 103/06 103/06 C 107/38 107/38 125/02 125/02 145 / 14 145/14 145/22 145/22 145/24 145/24 149/14 149/14 151/04 151/04 169/04 169/04 G02B 7/02 G02B 7/02 Z G03B 9/10 G03B 9 / 10 A 9/36 9/36 A 17/02 17/02 // (C08L 101/00 C08L 27:18 27:18) C10N 10:12 C10N 10:12 20:06 Z 20:06 30:00 D 30 : 00 Z 40:06 40:06 F-term (reference) 2H044 AJ05 2H081 AA03 AA08 AA19 AA21 AA43 AA44 BB31 2H100 BB03 EE00 EE04 4H104 AA04A AA04C AA19 A02 LA4A02A1A02A1A02A1A02A1A02A1A02A1A02A1A02A1A02A1A02A1A02A1A02A1A02A1A02 BN151 CF061 CF071 CF161 CG001 CH071 CH091 CL001 CM041 CN011 DA016 DA017 DA028 DA037 DG028 DL007 FA037 FD017 FD106 FD172 FD178 GP00

Claims (6)

[Claims] 1. A thermoplastic resin containing 0.1 to 20% by weight.
Carbon nanotubes are added, the surface resistance is 10 ¹¹
An antistatic resin material for optical devices, which has antistatic performance at Ω or less. 2. A thermoplastic resin, PC, PBT,
PET, ABS, PA, PS, PPS, LCP, PE
The antistatic resin material for optical equipment according to claim 1, which is selected from I, PEEK, PMMA, PPE, POM resins or alloys thereof. 3. Carbon black is added to the resin in an amount of 0.1.
The antistatic resin material for an optical device according to claim 1 or 2, wherein the antistatic resin material is added in an amount of 10% by weight to improve antistatic property and light blocking property. 4. The antistatic resin material for an optical device according to claim 1, which contains a reinforcing material made of glass fiber or carbon fiber in a proportion of 1 to 30% by weight. 5. The antistatic resin material for an optical device according to claim 1, wherein a lubricant selected from PTFE, graphite and molybdenum disulfide is added in a proportion of 1 to 30% by weight. 6. A molded product, such as a shutter base plate for mounting a shutter blade for a camera, a blade retainer, an intermediate plate, or a lens barrel, a mirror box, a camera body, etc. which is averse to static electricity generation. A component for optical equipment, characterized by being molded from the above antistatic resin material.