JP2010284859A - Thin-wall molded member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin-wall molded member such as a diaphragm blade and a shutter blade. <P>SOLUTION: The thin-wall molded member is formed of a material obtained by mixing 2 to 10 wt.% of a carbon nanotube having a length/diameter ratio of not more than 500 and a diameter of not more than 200 nm in a PC resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thin molded member, and more particularly to a thin molded member used for an optical product.

  As a thin molded member used as an optical product, there is a lens fixing member for fixing a diaphragm blade, a diaphragm, a lens and the like. The diaphragm blades and the diaphragm are peripheral members of an optical lens such as a digital camera or a film camera, and have a function of adjusting a light amount or shielding light.

  About such a diaphragm blade, although it considers manufacturing by resin molding from viewpoints, such as cost, it is difficult to implement | achieve from the characteristic requested | required of a diaphragm blade. That is, according to an ordinary resin forming method, a thin member having a thickness of 200 μm or less is remarkably deteriorated in resin filling property, so that it is difficult to perform molding by resin molding. Even if it can be formed by filling the resin, the mechanical strength is not sufficient, and it is difficult to obtain a product having sufficient function due to breakage or wear during use. Specifically, the diaphragm blades have good light blocking properties to block light, less friction is generated due to the rubbing operation, that is, a low dynamic friction coefficient, and even if friction heat is generated due to the rubbing operation, it is easy to dissipate heat. That is, a high thermal conductivity is required. Also, shutter blades used for lens shutters in digital cameras, film cameras, and the like are required to have the same characteristics as the above-described diaphragm blades.

  For this reason, thin-walled molded members such as diaphragm blades are manufactured by pressing a metal plate, etc., and then performing a rust prevention treatment (plating treatment) and applying a blackening coating to prevent light reflection. is doing. Therefore, the manufacturing time has been prolonged, and there are problems of restrictions such as high cost and design.

JP 2007-65494 A

  The present invention has been made in view of the above description, and provides a thin molded member that can be manufactured at low cost by resin molding or the like.

  The present invention is characterized in that it is formed of a material in which 2 to 10 wt% of carbon nanotubes having a length / diameter of 500 or less and a diameter of 200 nm or less are mixed in a PC resin.

  Further, the present invention produces a pellet in which carbon nanotubes having a length / diameter of 500 or less and a diameter of 200 nm or less are mixed in PC resin in an amount of 2 wt% to 10 wt%, and injection molding is performed using the pellet. It is what was manufactured by.

  In addition, the present invention is characterized in that the carbon nanotube is mixed by 4 wt% to 8 wt%.

  Further, the present invention is characterized in that a resin material of ABS, PPS, LCP, PS, PP is used instead of the PC resin.

  Further, the present invention is characterized in that the thickness of the thin portion of the thin molded member is 70 μm or more and 200 μm or less.

  In the present invention, the thin molded member is a diaphragm blade, a shutter blade, a finder, or a lens fixing member of a camera.

  According to the present invention, it is possible to manufacture a thin molded member at low cost by resin molding or the like.

Configuration diagram of diaphragm blades in the present embodiment Flowchart of a method for manufacturing a thin molded member in the present embodiment Figure of tensile strength characteristics for thin molded parts Dynamic friction coefficient characteristics diagram for thin molded parts Thermal conductivity characteristics diagram for thin molded parts Photo before and after heat treatment of thin molded parts Diagram showing coefficient of linear expansion and deformation in thin-walled molded members Perspective view (1) of another application example of the thin molded member in the present embodiment Perspective view (2) of another application example of the thin molded member in the present embodiment Configuration diagram of another application example of thin molded member in the present embodiment

  The form for implementing this invention is demonstrated below.

(Aperture blade)
FIG. 1 shows a diaphragm blade 10 in the present embodiment. The lens unit diaphragm device 20 in the digital camera includes a plurality of diaphragm blades 10. The diaphragm blade 10 is formed by a diaphragm blade body 11 and a shaft portion 12 formed in a protruding shape on the diaphragm blade body 11, and the diaphragm blade body 11 and the shaft portion 12 have an integral structure. The thickness t of the diaphragm blade body 11 is 70 to 150 μm, and the height a of the protruding portion of the shaft portion 12 is about 0.5 mm. The surface of the diaphragm blade body 11 has a mat shape in which minute irregularities are irregularly formed, and the color of the diaphragm blade body 11 is black to prevent reflection of light on the diaphragm blade.

  The material constituting the diaphragm blade 10 uses a PC (Polycarbonate) resin as a base material, and the PC resin has a carbon nanotube (CNT: Carbon nano tube) having a diameter of 200 nm or less and a length / diameter of 500 or less. ). The carbon nanotube is a substance in which a six-membered ring network (graphene sheet) made of carbon has a single-layer or multilayer coaxial tube. The carbon nanotubes added to the PC resin are 0.5 wt% to 20 wt%, preferably 2 wt% to 10 wt%, and more preferably 4 wt% to 8 wt%. Since PC resin has high physical properties such as heat resistance and flame retardancy and is inexpensive, it is a highly useful material when forming a thin molded member at low cost. By adding such a carbon nanotube having the above composition to the PC resin, a thin molded member having desired characteristics can be obtained at low cost. The thickness of the thin portion of the thin molded member formed in this way is 70 μm or more and 200 μm or less, and more preferably 100 μm or more and 150 μm or less.

(Manufacturing method of diaphragm blades)
Next, the manufacturing method of the aperture blade which is a thin molded member in this Embodiment based on FIG. 2 is demonstrated.

  First, as shown in step 102 (S102), the PC resin is pulverized. Specifically, it grind | pulverizes so that it may become a powder form whose average particle diameter is 0.5 mm or less.

  Next, as shown in step 104 (S104), stirring and mixing are performed. Specifically, 4 wt% to 8 wt% of carbon nanotubes are mixed into a PC resin that has been pulverized into a powder form and mixed by stirring.

  Next, as shown in step 106 (S106), pellet manufacturing is performed. Specifically, in step 104, pellets are manufactured by applying a mixture of carbon nanotubes mixed with PC resin to an extruder.

  Next, as shown in step 108 (S108), the pellets produced in step 106 are dried.

  Next, as shown in step 110 (S110), pellet production is performed again. Specifically, the pellets produced in step 108 are produced by re-extruding the pellets. Thereby, the rice grain size pellet for injection molding is produced. The reason why the pellets are manufactured again in this way is that the carbon nanotubes are more uniformly dispersed in the PC resin.

  Next, as shown in step 112 (S112), injection molding is performed. Specifically, a thin molded member such as a diaphragm blade in the present embodiment is formed by performing injection molding using the pellet manufactured in step 110. Thin-walled molded parts have a thin molded part thickness of 70 to 150 μm, so as an injection molding machine, a high-speed high-pressure high-pressure injection molding machine with an injection speed of 500 m / s or more and an injection pressure of 200 Mpa or more. Is used. The pellets produced in the plasticizing cylinder of this high-speed high-pressure injection molding machine are supplied, melt-plasticized in this plasticizing cylinder, and the melt-plasticized material is injected and filled into the mold at high speed and high pressure. The diaphragm blades in the present embodiment are formed by cooling and solidifying with the above.

  As described above, the diaphragm blades in the present embodiment can be manufactured in a short time by an injection molding machine, the manufacturing cost can be reduced, and furthermore, the shape can be produced in various shapes, so that the selection of the design is possible. Can be widened.

(Physical properties of thin molded parts)
Next, the physical properties of the thin molded member in the present embodiment will be described. The thin molded member in the present embodiment is formed of a material in which 4 wt% to 8 wt% of carbon nanotubes having a diameter of 200 nm or less and a length / diameter of 500 or less are added to PC resin.

  FIG. 3 shows the tensile strength characteristics. As shown in the figure, the tensile strength of the PC resin alone is slightly less than 51 MPa, while that in which 4 wt% of the carbon nanotube is mixed in the PC resin is 52 to 53 MPa, and the carbon nanotube is added to the PC resin. When 8 wt% is mixed, the pressure is 56 MPa. Thus, by mixing 4 wt% to 8 wt% of carbon nanotubes in the PC resin, the tensile strength and Young's modulus can be improved, and the mechanical strength of the formed product can be increased.

  Next, FIG. 4 shows dynamic friction coefficient characteristics. Specifically, the coefficient of dynamic friction was measured with a friction tester using a ball as a test piece for the PC resin alone and the PC resin mixed with 8 wt% of carbon nanotubes. As a result, in the case of only PC resin, the dynamic friction coefficient is high from the beginning, and then rapidly increases. After 20 times or more, the dynamic friction coefficient becomes 0.4 or more, whereas 8 wt% of carbon nanotubes are mixed in the PC resin. The increase in the dynamic friction coefficient is moderate, and the dynamic friction coefficient is kept low at 0.2 or less even at the 100th time. Thus, in the case where carbon nanotubes are mixed with 8 wt% of PC resin, the coefficient of dynamic friction can be kept low, so that a smooth movement can be maintained for a long time in a thin molded member having a movable part such as a diaphragm blade. Can do.

  Next, FIG. 5 shows thermal conductivity characteristics. As shown in the figure, the thermal conductivity of the PC resin alone is a low value of about 0.2 W / m · K, whereas the value obtained by mixing 4 wt% of carbon nanotubes in the PC resin is about 0.1. The value is 4 W / m · K, and the value obtained by mixing 8 wt% of carbon nanotubes in the PC resin is as high as about 0.6 W / m · K. Thus, by mixing 4 wt% to 8 wt% of carbon nanotubes in the PC resin, the thermal conductivity can be increased, and a thin molded member with good heat dissipation characteristics can be obtained.

  Next, FIG. 6 shows the heat treatment at 180 ° C. for 30 minutes for the PC resin alone, the PC resin mixed with 4 wt% carbon nanotubes, and the PC resin mixed with 8 wt% carbon nanotubes. The photograph of the shape of a bowl is shown. FIG. 6 (a) shows the state of each member before the heat treatment, and FIG. 6 (b) shows the state after the heat treatment at 180 ° C. for 30 minutes. . In the case of only the PC resin, the member is deformed and contracted by this heat treatment, whereas in the case where 4 wt% of carbon nanotubes are mixed in the PC resin, the heat treatment is slightly deformed, In the case of 8 wt% of carbon nanotubes mixed in the PC resin, no deformation due to this heat treatment was confirmed, and the shape before the heat treatment was maintained. Thus, it is confirmed that heat resistance can be improved by mixing 4 wt% to 8 wt% of carbon nanotubes in the PC resin.

  Next, in FIG. 7, the linear expansion coefficient and the amount of thermal deformation were measured for the PC resin alone, the PC resin mixed with 4 wt% carbon nanotubes, and the PC resin mixed with 8 wt% carbon nanotubes. Results are shown. From this figure, the linear expansion coefficient is reduced to about 65% and the amount of thermal deformation is also reduced to about 60% when the PC resin is mixed with 4 wt% of carbon nanotubes in the PC resin alone. In addition, when the PC resin is mixed with 8 wt% of carbon nanotubes, the coefficient of linear expansion is reduced to about 50% and the amount of thermal deformation is reduced to about 36%. Thus, by mixing 4 wt% to 8 wt% of carbon nanotubes in the PC resin, the linear expansion coefficient can be suppressed low, and thermal deformation can be suppressed. The amount of deformation was measured at + 20 ° C. by heating a sample of 2 mm thickness and 5 mm square with a TMA tester to 150 ° C. under a load of 1.5 g. The TMA test performed in this embodiment is a support tube: compression weight method, sample length: 5 mm, load: 14.7 mN, heating rate: 5 ° C./min, temperature range: room temperature to refractive temperature ( 150 ° C. + 20 ° C.) Atmosphere: air static.

  As described above, in the thin molded member in the present embodiment, good characteristics can be obtained by mixing 4 wt% to 8 wt% of carbon nanotubes in the PC resin. Note that the carbon nanotubes mixed in the PC resin need to be mixed in at least 4 wt% in order to obtain the above-mentioned good characteristics, and may be 8 wt% or less from the viewpoint of cost reduction. preferable. Since carbon nanotubes are expensive, in terms of cost, it is preferable that the amount of mixing is as small as possible. For this reason, it is preferable that the amount of mixing of carbon nanotubes to obtain desired characteristics is as small as possible. In addition, if the amount of carbon nanotubes mixed in the PC resin is large, it becomes difficult to form a molded member thinly and the moldability is lowered, so the carbon nanotubes mixed in the PC resin is in the range of 4 wt% to 8 wt%. It is preferable that

  In this embodiment, PC resin is used. However, other resin materials such as ABS (Acrylonitrile butadiene styrene), PPS (Polyphenylenesulfide), LCP (Liquid Crystal Polymer) are used. : Liquid crystal polymer), PA (polyamide: Polyamide), POM (polyoxymethylene: Polyacetal), PS (polystyrene: Polystyrene), PP (polypropylene: Polypropylene), etc. Obtainable. In this case, the preferable composition range of the carbon nanotubes mixed in these resin materials is in the range of 0.5 wt% to 20 wt%, more preferably in the range of 2 wt% to 10 wt%, and still more preferably 4 wt%. % To 8 wt%. The physical properties of the thin molded member described above, that is, based on experience, based on FIGS. 3 to 7, even if the carbon nanotube composition range is 2 wt% to 10 wt%, the range is 4 wt% to 8 wt%. It is considered that the same effect as in the case of can be obtained.

(Specific examples of thin molded parts)
Next, a specific example of the thin molded member in the present embodiment will be shown. 8, 9, and 10 are specific examples of the thin-walled molded member in the present embodiment. FIG. 8A is a shutter blade used in the lens shutter mechanism which is a thin molded member in the present embodiment, and FIG. 8B is a viewfinder mask which is a thin molded member in the present embodiment. FIG. 9A shows a diaphragm blade having another shape in the present embodiment, and FIG. 9B shows a lens fixing member for fixing the lens in the present embodiment. Is a light amount adjusting member used when using the zoom in the present embodiment, and FIG. 9D is a diaphragm blade of still another shape in the present embodiment. FIG. 10 is a lens fixing member of another shape for fixing the lens in the present embodiment, FIG. 10 (a) is a perspective view of the lens fixing member, FIG. 10 (b) is a front view, and FIG. FIG. 10C is a side view, and FIG. 10D is a cross-sectional view taken along a broken line 10A-10B in 10B.

  The thin molded member in the present embodiment can be applied to various thin members. In particular, the thin molded member is an optical member such as a digital camera or a film camera, and can be used as a member having a thin portion.

  As mentioned above, although the form which concerns on implementation of this invention was demonstrated, the said content does not limit the content of invention.

10 Diaphragm blade 11 Diaphragm blade body 12 Shaft

Claims (6)

  A thin-walled molded member formed of a material in which carbon nanotubes having a length / diameter of 500 or less and a diameter of 200 nm or less are mixed in PC resin in an amount of 2 wt% to 10 wt%. A pellet in which 2 to 10 wt% of carbon nanotubes having a length / diameter of 500 or less and a diameter of 200 nm or less are mixed in a PC resin is prepared,
A thin-walled molded member manufactured by injection molding using the pellet.   The thin-walled molded member according to claim 1 or 2, wherein the carbon nanotube is a mixture of 4 wt% to 8 wt%.   4. The thin molded member according to claim 1, wherein a resin material such as ABS, PPS, LCP, PS, PP is used in place of the PC resin.   The thin molded member according to any one of claims 1 to 4, wherein a thickness of a thin portion of the thin molded member is 70 µm or more and 200 µm or less.   6. The thin molded member according to claim 1, wherein the thin molded member is a diaphragm blade, a shutter blade, a finder, or a lens fixing member of a camera.