JP2005153294A - Mold for molding plastic, plastic molded product, optical device and optical scanning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the dimensional precision of a plastic molded product by uniformizing the temperature distribution of a mold to prevent the lowering of the quality of the plastic molded product. <P>SOLUTION: In this mold for molding a plastic constituted using at least one member comprising a metal-ceramic composite material, coating layers 13,14 and 15 are formed on a part of or the whole of the member comprising the metal-ceramic composite material. The coating layer 13 is a nickel plating layer formed by electroless plating and the coating layer 15 is a mixture layer of nickel and a fluoroplastic formed by electroless plating. The coating layer 14 is either one of a titanium nitride film, a titanium carbide film and a titanium carbonitride film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plastic optical element applied to a laser type digital copying machine, a laser printer, or an optical apparatus such as a facsimile apparatus or an optical apparatus such as a video camera, and a molding die for the plastic optical element. The present invention relates to a thermoplastic molded article, an optical scanning device or an optical device, and a plastic molding die that require a dimension such as a high-precision optical mirror surface.

In recent years, plastic molded products having various shapes have been used for various purposes. As a method for manufacturing the molded product, it is common to use an injection molding method that is low in manufacturing cost and suitable for mass production. When manufacturing a plastic molded product by the injection molding method, in the process of injecting and filling the heat-melted resin material into the mold and cooling and solidifying it, by making the resin pressure and resin temperature in the mold uniform, Desired shape dimensional accuracy and internal distortion accuracy are ensured. In this method, the temperature distribution immediately after the resin is filled has a distribution corresponding to the resin volume in the cavity.
For this reason, when the cavity shape is complicated and there is an extreme difference in thickness, even if it is cooled as it is, the temperature distribution is not uniform, the shape accuracy deteriorates and optical distortion occurs, and high accuracy is required. This is particularly a problem with optical components and the like.
Here, the reason why the uneven temperature distribution becomes a problem will be described. In the injection molding method, after the molded product is taken out from the mold, it is cooled and contracted by the outside air. In other words, even if the shape is transferred in the mold, if the molded product has a temperature distribution when the molded product is taken out, the shape accuracy deteriorates due to the difference in shrinkage after taking out from the mold. Become.
In addition, in the conventional mold temperature control method, the temperature distribution is naturally different between immediately after injection filling where the temperature difference between the resin and the mold is severe and before mold release where the temperature difference is small. It is difficult to keep. Furthermore, even when the conditions change, such as changing the set temperature of the mold, there is a problem that the temperature distribution changes and the uniformity cannot be maintained.
JP-A-11-170323 JP 2002-155324 A

In order to improve the temperature non-uniformity which is the conventional problem, the following two methods are conceivable.
First, as described in Patent Document 1, at least two bar heaters are provided inside or outside the mold so as to face the cavity of the mold, and the heating elements inside the bar heater are divided into a plurality of parts. When controlling the temperature of the mold that heats the individual heating elements, classify each heating element of the rod heater into at least two groups and set the temperature cycle individually for each group. This is a method of controlling the heating amount of the heating element based on the temperature control individually set at a plurality of locations of the mold. This method has a great effect on uniforming the temperature distribution, but with the increase in the number of temperature control points, there are problems in operability during molding and setup including maintenance. In particular, it is more conspicuous in multi-cavity molding.
A second method is to use a high thermal conductivity material such as copper or copper alloy, or aluminum or aluminum alloy for cavity nesting. In order to make the mold temperature uniform, when using a high thermal conductivity material for the mold material, for example, when copper or aluminum is used as the high thermal conductivity material, compared to conventional steel for molds, Since copper and aluminum have a large coefficient of thermal expansion, the shape dimension is strongly affected by the mold temperature and the like, and the shape dimension accuracy of the molded product is inferior. Moreover, when using copper, aluminum, etc. and other steel materials together for a metal mold | die, there exists malfunctions, such as bad contact between nesting.
Furthermore, as described in Patent Document 2, there is a method of using a metal-ceramic composite material as a high thermal conductive material. The metal-ceramic composite material is manufactured by a known non-pressure permeation method, etc., and the ceramic content can be changed over a wide range, and the uniform dispersibility of the ceramic is also good, and has been developed in various applications. Due to a defect such as a nest peculiar to the composite material, a powdery foreign substance is generated on the surface, which causes a defect such as a foreign substance that deteriorates the quality of a molded product, contamination, and a decrease in yield. In addition, when a metal-ceramic composite material is applied to a sliding portion or the like, there is a problem that a mating member to be contacted is cut and time is required for maintenance of the mold.
The present invention has been made in view of the above, and a plastic molded product and a molded product that make the temperature distribution of the mold uniform, improve the dimensional accuracy of the plastic molded product, and do not lower the quality of the molded product. An object of the present invention is to provide a mold for plastic molding, an optical scanning device incorporating a plastic molded product, and an optical device.

In order to solve the above-described problems and achieve the object, the invention according to claim 1 is directed to a metal mold for plastic molding constituted by using at least one member made of a metal-ceramic composite material. A coating layer is formed on a part or all of a member made of a ceramic composite material.
The invention according to claim 2 is the invention according to claim 1, wherein the coating layer is a nickel plating layer formed by electroless plating.
The invention according to claim 3 is the invention according to claim 1, wherein the coating layer is a mixture layer of nickel and a fluororesin formed by electroless plating.
The invention according to claim 4 is the invention according to claim 1, wherein the coating layer is any one of a titanium nitride film, a titanium carbide film, and a titanium carbonitride film.
The invention according to claim 5 is the invention according to claim 2, characterized in that the transfer surface of the cavity is composed of a nickel plating layer of a metal-ceramic composite material.
The invention according to claim 6 is the invention according to claim 3, characterized in that the surface other than the transfer surface of the cavity is a mixture layer of a metal-ceramic composite material.

The invention according to claim 7 is the invention according to claim 4, wherein the surface other than the transfer surface of the cavity is any one of a titanium nitride film, a titanium carbide film, and a titanium carbonitride film of a metal-ceramic composite material. It is comprised by these.
The invention according to claim 8 is the invention according to claim 2 or 5, characterized in that the nickel plating layer has a thickness of 20 μm or more.
The invention according to claim 9 is the invention according to claim 3 or 6, characterized in that the thickness of the mixture layer is 20 μm or less.
The invention according to claim 10 is the invention according to claim 4 or 7, wherein any one of the titanium nitride film, the titanium carbide film, and the titanium carbonitride film has a thickness of 10 μm or less. It is characterized by.
The invention according to claim 11 is characterized in that, in the invention according to claim 3, 6 or 9, the fluorine resin in nickel in the mixture layer is 10 to 30% by volume.
The invention according to claim 12 is the invention according to any one of claims 1 to 11, wherein the metal-ceramic composite material has ceramic powder or ceramic fiber as a reinforcing material and aluminum or an aluminum alloy as a matrix. Features.
The invention according to claim 13 is characterized by a plastic molded product molded by the plastic molding die according to any one of claims 1-12.
The invention according to claim 14 is characterized by an optical scanning device or an optical device incorporating the plastic molded product according to claim 13.

According to the first aspect of the present invention, in a plastic molding die configured by using at least one member made of a metal-ceramic composite material, part or all of the member made of the metal-ceramic composite material In addition, the formation of a coating layer eliminates the generation of powdery foreign matter on the surface due to defects such as the nests peculiar to composite materials, and reduces foreign matter and contamination defects in molded products. And the yield can be improved. Moreover, in the sliding location, it is possible to prevent problems such as scraping the mating member that comes into contact, and the time for mold maintenance can be reduced. Furthermore, by selecting a metal-ceramic composite material having a high thermal conductivity, the mold temperature distribution near the cavity can be made extremely small.
Further, according to the invention of claim 2, since the coating layer is a nickel plating layer formed by electroless plating, the nickel plating layer can be made amorphous, so there is no influence of crystal grain boundaries, As a result, post-processing such as cutting, grinding, and polishing is easy, and a mold having excellent surface shape accuracy can be manufactured.
According to the invention of claim 3, the coating layer is a mixture layer of nickel and fluororesin formed by electroless plating, so that wear resistance (sliding property) at the interface between the mold inserts is obtained. ) Can be improved. Moreover, since it contains a fluororesin, the releasability from the resin can be improved.

According to the invention of claim 4, the coating portion is any one of a titanium nitride film, a titanium carbide film, and a titanium carbonitride film, so that the wear resistance at the interface between the mold inserts is improved. Abrasion (slidability) and impact resistance can be improved.
According to the invention of claim 5, a mold having excellent surface shape accuracy can be manufactured by forming the transfer surface of the cavity using a nickel plating layer of a metal-ceramic composite material. The plastic molded product manufactured from the mold has excellent surface shape accuracy.
According to the invention of claim 6, the surface other than the transfer surface of the cavity is configured by using the metal-ceramic composite material mixture layer, so that the releasability from the resin can be improved. .
According to the invention of claim 7, the surface other than the transfer surface of the cavity uses any one of the titanium nitride film, titanium carbide film, and titanium carbonitride film of the metal-ceramic composite material. By being comprised, the mold release property with resin can be improved.
Moreover, according to the invention concerning Claim 8, since the nickel plating layer has a thickness of 20 μm or more, it is possible to secure a machining margin at the time of post-processing, and to provide a mold having excellent surface shape accuracy. Can be manufactured.
Moreover, according to the invention concerning Claim 9, adhesiveness with a base material and mechanical strength can be obtained because a mixture layer is 20 micrometers or less in thickness.

Moreover, according to the invention concerning Claim 10, when any one of the titanium nitride film, the titanium carbide film, and the titanium carbonitride film has a thickness of 10 μm or less, it is in close contact with the base material. Sex can be secured.
Moreover, according to the invention concerning Claim 11, when the fluororesin in a mixture is 10 volume% or more, the mold release property with resin and the abrasion resistance in the interface between metal mold inserts are securable. Moreover, the outstanding dimensional accuracy is securable because the fluororesin in a mixture is 30 volume% or less.
According to the invention of claim 12, the metal-ceramic composite material is a metal-ceramic composite material having ceramic powder or ceramic fiber as a reinforcing material and aluminum or an aluminum alloy as a matrix. The rate can be selected significantly. As a result, the coefficient of thermal expansion and the thermal conductivity can be selected significantly, and the metal-ceramic composite material can be applied to a plastic mold in various places and combinations.
According to the invention of claim 13, the plastic molded product molded by the plastic molding die according to claims 1 to 12 has an extremely large variation in shrinkage of the plastic molded product after being taken out from the mold. There are few and highly accurate shape dimensions. Further, the plastic molded product has less foreign matter and contamination.
According to the invention of claim 14, a high-precision image can be obtained by using the plastic molded product of claim 13 for an optical scanning device or an optical device.

Exemplary embodiments of a plastic molding die and a plastic molded product according to the present invention will be explained below in detail with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a schematic view of a scanning lens according to the first embodiment of the present invention.
In FIG. 1, a scanning lens 1 used in a laser printer or the like has an upper surface and a lower surface that are optical surfaces 2, and when incorporated in a laser printer, is used so that a laser beam is transmitted from the lower surface toward the upper surface. Plastic optical element. The material of the scanning lens is, for example, cycloolefin polymer Zeonex resin (trade name) manufactured by Nippon Zeon.
The scanning lens shown in FIG. 1 has a thick central portion in the longitudinal direction and a thin end portion in the longitudinal direction, and the case where molding processing is performed with the following dimensions will be described.
Resin to be used: Zeonex (Glass transition temperature 138 ° C. The test method used differential scanning calorimetry (DSC))
Scanning lens 1 shape dimensions: Center lens thickness Ha: 14 mm, end lens thickness Hu: 7 mm, short length D: 14 mm, long length L: 220 mm
FIG. 2 is a schematic cross-sectional view of the periphery of the cavity of the injection mold 3 used for molding the scanning lens of FIG. In the mold of FIG. 2, a pair of mirror pieces 4 that form an optical surface, a side piece 5 that supports the mirror piece 4, an ejector pin 6, a pair of cavity inserts 7 that form a surface other than the optical surface, and a slidable structure. Is formed of a pair of sliding pieces 8 and has a cavity 9. A drive unit (not shown) is connected to the pair of sliding pieces 8 provided slidably, and the side piece 5 is further connected to the cartridge heater 10 and the thermocouple 11 in order to heat the mold. The cartridge heater 10 and the thermocouple 11 are connected to another temperature control device (not shown) prepared outside the mold. The angular pin 12 is attached to a mold base (not shown) on the fixed side.
Here, all the mold inserts are made of a metal-ceramic composite material. As shown in FIG. 3, the mirror piece 4 has a nickel plating layer 13 formed on the optical surface and ejector pins 6 other than the optical surface. The titanium nitride film 14 is formed on the entire surface including the sliding holes. Further, as shown in FIG. 4, the pair of cavity inserts 7 that form surfaces other than the optical surface has a titanium nitride film 14 formed on the entire surface, and the pair of sliding pieces 8 that are slidably provided are shown in FIG. As shown in FIG. 5, a mixture layer 15 of nickel and fluororesin is formed on the entire surface.

In molding the scanning lens 1 shown in FIG. 1 with the above-described mold, the following steps are taken.
The injection mold 3 is set in an injection molding machine (not shown). This mold is heated by the cartridge heater 10 so as to be 135 ° C. just below the glass transition temperature of the resin material used, and the cavity 9 is filled with molten resin. Then, the temperature of the cartridge heater 10 is adjusted so that the mold is maintained at a predetermined temperature that is equal to or lower than the glass transition temperature of the resin material used.
Next, a resin pressure is generated in the cavity 9 so that the resin is brought into close contact (transfer) with the pair of mirror surface pieces 4 forming the optical surface. At this time, the pair of sliding pieces 8 slidably provided are placed when the resin pressure in the cavity becomes zero so that sinks (concave portions) due to shrinkage during the resin cooling process do not occur on the optical surface. The resin is slid away from the resin, and a gap is forcibly formed between the resin and the sliding piece 8, and the sink is guided to the surface in contact with the sliding piece 8. Thereafter, the mold is opened when the temperature of the molded product becomes uniform. At this time, the cavity insert 7 is slid by the angular pin 12. Next, the solidified plastic molded product is projected by the ejector pins 6, taken out from the mold using a molding product take-out device (not shown), and allowed to cool to room temperature.
In the molding described above, sink marks (concave portions) are induced on the surface in contact with the sliding piece 8, so that the optical surface 2 can be prevented from sinking, and the desired optical surface can be faithfully transferred in a short molding cycle. Can do. In addition, since the resin internal pressure acting on the optical surface during cooling can be made close to atmospheric pressure (molding is performed so that the resin pressure in the cavity becomes zero before mold opening), a molded product with low internal distortion is obtained. be able to.

Here, the metal-ceramic composite material of the mold used in the above molding will be described. As the metal-ceramic composite material, Selenx (trade name) PSI-55 manufactured by Selenx is used. PSI-55 is a composite of Al-Si aluminum alloy and SiC ceramics by non-pressure metal penetration method. It has a SiC content of 55% by volume. The reason why the aluminum alloy is made of an Al-Si alloy is that it has good wettability with ceramics, so that non-pressurized permeation is possible, and further, a defect portion where the metal does not permeate hardly occurs. Because.
The metal-ceramic composite material is highly rigid, has a smaller coefficient of thermal expansion than aluminum alloys and copper alloys, and is excellent in thermal conductivity. For example, compared to the heat conductivity of 25 W / m · ° C. of metals conventionally used in steel materials, such as (SUS), the heat conductivity of Selencus PSI-55 made by Selangs is 159 W / m · ° C. The temperature distribution can be greatly improved by more than double. Specifically, the temperature distribution around the cavity can be equalized within 1 ° C.
In addition, metal-ceramic composite materials can be applied to plastic molding dies because of their high thermal conductivity and low coefficient of thermal expansion. However, compared to conventional steel materials, surface roughness and hardness, Abrasion is inferior. Therefore, in the mold in this example, a part or all of the insert is covered with a film adapted to the function of each mold insert.
In the above mold, the mirror piece 4 is formed by coating titanium nitride with a thickness of 3 μm on the entire surface including the sliding holes of the ejector pins 6 other than the optical surface, and further, by electroless plating on the surface forming the optical surface. The plating layer 13 is coated with a thickness of 100 μm. After the heat treatment, the nickel plating layer 13 is subjected to aspherical cutting. Since nickel plating formed by electroless plating is amorphous, there is no influence of crystal grain boundaries compared to the crystalline state, and processing is easy, and processing accuracy is easy to obtain. In the mold of this example, the thickness is set to 100 μm for the purpose of securing a processing margin at the time of post-processing, but 20 μm or more is enough to fulfill the function as an optical surface. Further, when a highly accurate shape and dimension are required as in this example, it is necessary to process the metal-ceramic composite material in consideration of the thickness of the coating layer. The titanium nitride film 14 is formed by a physical vapor deposition method (PVD) such as a vacuum vapor deposition method, a sputtering method, or an ion plating method. In this example, the titanium nitride film 14 is formed by ion plating. The titanium nitride film 14 formed by ion plating is dense and has good adhesion, and is excellent in wear resistance and impact resistance. In consideration of wear resistance and impact resistance, as well as adhesion to the base material, any of titanium nitride film, titanium carbide film and titanium carbonitride film can be applied as a coating layer. It is. As in this example, when used as a sliding hole for the ejector pin 6, the effect is more remarkable, but it is desirable that the ejector pin 6 is a round pin in order to prevent further problems.

Next, the pair of cavity inserts 7 that form surfaces other than the optical surface will be described. The cavity insert 7 has a titanium nitride film 14 with a thickness of 3 μm on the entire surface. Since the cavity insert 7 is a mechanism that slides when the mold is opened by the angular pin 12 attached to the fixed side in order to reduce the mold release resistance when the molded product is protruded, wear resistance is required. The thickness of the titanium nitride film 14 is preferably 10 μm or less because the adhesive strength is lowered when the thickness is 10 μm or more.
Next, a pair of sliding pieces 8 provided slidably will be described. The sliding piece 8 has a mixture layer 15 of nickel and fluororesin on the entire surface. The mixed layer 15 of nickel and fluororesin in this example is formed by a nif grip process, and electroless nickel and Teflon (registered trademark) are co-deposited in a processing solution, and further, a heat treatment is performed after the film formation so that the adhesion strength is increased. Has improved. The thickness is 5 μm over the entire surface. As described above, since the sliding piece 8 is separated at the time of molding, it is required to release from the resin. If the releasability is poor, a force for pulling the resin occurs when the mold is separated, which adversely affects the transfer of the optical surface. Further, since the sliding piece 8 slides, wear resistance is also required. By having the mixture layer 15 of nickel and fluororesin as in this example, it is possible to improve the releasability with the resin and the wear resistance with other mold inserts. In this example, the thickness is 5 μm, but considering the mechanical strength, a thickness of 20 μm or less is desirable. Further, in this example, Teflon (registered trademark) is 20% by volume, but 10% by volume or more is necessary in order to secure release properties and wear resistance. Furthermore, in consideration of the thermal expansion of the Teflon (registered trademark) to be contained, it is desirable that it is 30% by volume or less in order to ensure dimensional accuracy.

The plastic mold described above is less likely to have foreign matter mixed in the molded product, and the mold temperature distribution near the cavity is extremely small. In addition, the plastic molded product manufactured according to this example has extremely small variation in the amount of shrinkage of the plastic molded product after being taken out from the mold, has a very high precision shape, and has no foreign matter or contamination. Few.
Further, in this example, the above-described scanning lens is molded, but the above-mentioned effects can be obtained with plastic molded products having all shapes of thick and uneven thickness.
Also, a transfer surface (optical surface) shape that requires a highly accurate shape dimension can be applied to all shapes such as a flat surface, a spherical surface, an aspherical surface, a free-form surface.
This example relates to a cycloolefin polymer as an object of molding, but the present invention is applicable to all thermoplastic plastics that can obtain the above-described effects regardless of the resin material used. In other words, when there is a significant temperature difference between the mold take-out temperature and the ambient temperature of the molded product, when the molded product is thick or uneven, the molded product is prominent for plastic molded products that require highly accurate shape dimensions. It has a great effect.
The above description describes an example in which the resin material is molded into a desired molded product shape by the injection molding method in the mold, but the present invention makes the mold temperature uniform and removes the mold from the mold. Since it is characterized by reduced variation in the amount of shrinkage after molding and no foreign matter / contamination, it is not limited to molding methods. In addition to injection molding, injection compression / press molding, gas assist molding and extrusion It can be applied to various molding methods such as molding.

(Second Embodiment)
FIG. 6 is a schematic view of a scanning lens according to the second embodiment of the present invention.
In FIG. 6, a scanning lens 16 used in a laser printer or the like has an upper surface and a lower surface that are optical surfaces 2, and when incorporated in a laser printer, the scanning lens 16 is used so that a laser beam is transmitted from the lower surface toward the upper surface. Plastic optical element. The material of the scanning lens is polycarbonate resin (having PC optical grade).
The scanning lens 16 shown in FIG. 6 has a thick central portion in the longitudinal direction and a thin thickness portion at the longitudinal end, and the case where molding processing is performed with the following dimensions will be described.
-Resin used: PC (glass transition temperature 145 ° C test method DSC)
Scanning lens 16 shape dimensions: center lens thickness Ha: 35 mm, end lens thickness Hu: 5 mm, short length D: 10 mm, long length L: 160 mm
FIG. 7 is a schematic cross-sectional view of the periphery of the cavity of the injection mold 3 used for molding the scanning lens of FIG. The mold shown in FIG. 7 has a cavity 9 composed of a pair of mirror pieces 4 forming an optical surface and two pairs of cavity inserts 7 forming a surface other than the optical surface. Further, the cavity insert 7 includes an oil temperature adjusting pipe 17 and a thermocouple 11 for heating the mold.
Further, the mold inserts are all made of a metal-ceramic composite material, and the mirror piece 4 has a nickel plating layer 13 on the optical surface as shown in FIG. Furthermore, as shown in FIG. 9, the two pairs of cavity inserts 7 that form surfaces other than the optical surface have a titanium nitride film 14 on the two PL (parting line) surfaces and the cavity surface.

In molding the scanning lens 1 shown in FIG. 6 with the above-described mold, the following steps are taken.
The injection mold 3 is set in an injection molding machine (not shown), and oil is circulated through the oil temperature adjusting pipe 13 and heated so that the mold is 142 ° C. just below the glass transition temperature of the resin material used. Then, the cavity 9 is filled with molten resin. Then, the temperature of the oil in the oil temperature adjusting pipe 13 is adjusted so that the mold is maintained at a predetermined temperature that is equal to or lower than the glass transition temperature of the resin material used. Next, a resin pressure is generated in the cavity 9 so that the resin is brought into close contact with the pair of mirror surface pieces 4 forming the optical surface, and the solidified plastic molded product is then molded using a molded product take-out device (not shown). It is taken out from the room and allowed to cool to room temperature.
Here, the metal-ceramic composite material used is Selencus PSI-55 manufactured by Selencus, as in the first embodiment. The mirror piece 4 is coated with a nickel plating layer 13 with a thickness of 50 μm by electroless plating only on the surface forming the optical surface. After the heat treatment, the nickel plating layer 13 is subjected to aspherical cutting. By selectively having a coating layer as in this example, the manufacturing cost of the mold can be reduced. Moreover, when a highly accurate shape dimension is requested | required, it is necessary to process the metal-ceramics composite material in consideration of the thickness of a coating layer.
Next, the two pairs of cavity inserts 7 that form surfaces other than the optical surface will be described. In the cavity insert 7, a titanium nitride film 14 is formed with a thickness of 5 μm only on the PL surface and the cavity surface. Although a high pressure is applied to the PL surface when the mold is closed, the impact resistance can be improved and the PL surface can be prevented from being scraped by having the titanium nitride film 14 as in this example. . Moreover, the manufacturing cost of a metal mold | die can be reduced by having a coating layer selectively like this example.
The plastic molding die manufactured according to this example is unlikely to have foreign matters mixed in the molded product, and the mold temperature distribution near the cavity is extremely small. In addition, the plastic molded product manufactured according to this example has extremely small variation in the amount of shrinkage of the plastic molded product after being taken out from the mold, has a very high precision shape, and has little foreign matter and contamination. .

(Third embodiment)
FIG. 10 is a schematic view of a plastic mirror according to the third embodiment of the present invention.
In FIG. 10, a plastic mirror 18 used in a laser printer or the like is a plastic optical element that reflects a laser beam, for example, by depositing aluminum on the optical surface 2. The plastic mirror is made of polycarbonate resin (having PC optical grade). The plastic mirror 18 shown in FIG. 10 has a thin central portion in the longitudinal direction and a thick portion at the longitudinal end, and a case where molding is performed with the following dimensions will be described.
-Resin used: PC (glass transition temperature 145 ° C test method DSC)
Shape dimension of the plastic mirror 18: center lens thickness Ha: 6 mm, end lens thickness Hu: 15 mm, short length D: 14 mm, long length L: 260 mm
FIG. 11 shows a schematic cross-sectional view of a press molding die 19 used for molding the plastic mirror of FIG. The upper die plate 20 of the press molding die 19 has an upper mold member 21 that forms an optical surface, and the lower die plate 22 has a lower mold member 23 that forms a surface other than the optical surface. ing. Further, the upper mold member 21 and the lower mold member 23 are provided with a cartridge heater 10 and a thermocouple 11 in order to heat the mold, and the cartridge heater 10 and the thermocouple 11 are prepared outside the mold. It connects with another temperature control apparatus which is not illustrated. On the other hand, the lower mold member 23 is provided with a plastic substrate 24 made of a polycarbonate resin that has been processed in advance into a substantially final shape by injection molding.
The material of the mold 19 is made of a metal-ceramic composite material, and the upper mold member 21 that forms the optical surface has a nickel plating layer 13 on the optical surface and a titanium nitride film 14 on the PL surface. Further, the lower mold member 23 that forms a surface other than the optical surface has a titanium nitride film 14 on the PL surface and the cavity surface.

In molding the plastic mirror 18 shown in FIG. 11 with the above-described mold, the following steps are taken.
The press molding die 19 is heated by the cartridge heater 10 so as to be 150 ° C. higher than the glass transition temperature of the resin material used. Next, by lowering the upper die plate 20 of the press molding apparatus, a resin pressure is generated on the plastic base material 24, and the cavity surface is completely adhered. Then, with the mold and resin kept in close contact, the mold was slowly cooled to 120 ° C., which is lower than the glass transition temperature of the resin material used, at a rate of 1 ° C./min. Allow to cool to room temperature.
Here, the metal-ceramic composite material used is Selencus PSI-55 manufactured by Selencus, as in the first embodiment. The upper mold member 21 is formed by coating the nickel plating layer 13 with a thickness of 50 μm by electroless plating only on the optical surface, and further forming the titanium nitride film 14 with a thickness of 5 μm only on the PL surface. After the heat treatment, the nickel plating layer is subjected to aspherical cutting. As in this embodiment, by selectively having a coating layer, the manufacturing cost of the mold can be reduced. Moreover, when a highly accurate shape dimension is requested | required, it is necessary to process the metal-ceramics composite material in consideration of the thickness of a coating layer.
Next, the lower mold member 23 that forms a surface other than the optical surface will be described. The lower mold member 23 has the titanium nitride film 14 with a thickness of 5 μm only on the PL surface and the cavity surface. By selectively having a coating layer as in this example, the manufacturing cost of the mold can be reduced. The titanium nitride film 14 is excellent in releasability and wear resistance.
The plastic molding die manufactured according to the present example hardly mixes foreign matter into the molded product, and the mold temperature distribution near the cavity is extremely small. In addition, the plastic molded product manufactured according to this example has extremely small variation in the amount of shrinkage of the plastic molded product after being taken out from the mold, has a very high precision shape, and has little foreign matter and contamination. .

  As described above, the mold for plastic molding, the plastic molded product and the optical device, and the optical scanning device according to the present invention are useful for increasing the precision of the plastic molded product and the precision of the optical system. Suitable for optical equipment that obtains images.

1 is a schematic diagram of a scanning lens according to a first embodiment of the present invention. The cross-sectional schematic of the cavity periphery of a metal mold | die. Sectional drawing of a mirror surface piece. Sectional drawing of a cavity nest. Configuration diagram of sliding piece Schematic of the scanning lens of 2nd Embodiment of this invention. The cross-sectional schematic of the cavity periphery of a metal mold | die. Sectional drawing of a mirror surface piece. Sectional drawing of a cavity nest. Schematic of the plastic mirror of 3rd Embodiment of this invention. The cross-sectional schematic of the metal mold | die for press molding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Scan lens 2 Optical surface 3 Injection mold 4 A pair of mirror surface piece which forms an optical surface 5 A side piece which supports a mirror surface piece 6 Ejector pin 7 A pair of cavity inserts which form surfaces other than an optical surface 8 A sliding piece 9 Cavity 10 Cartridge Heater 11 Thermocouple 12 Angular Pin 13 Nickel Plating Layer 14 Titanium Nitride Film 15 Mixture Layer 16 of Nickel and Fluorine Resin 16 Scan Lens 17 Layer Oil Temperature Control Pipe 18 Plastic Mirror 19 Press Mold 20 Upper Die Plate 21 Upper die member 22 that forms an optical surface Lower die plate 23 Lower die member 24 that forms a surface other than the optical surface Plastic base material

Claims (14)

In a plastic molding die constituted by using at least one member made of a metal-ceramic composite material,
A mold for plastic molding, characterized in that a coating layer is formed on a part or all of the member made of the metal-ceramic composite material.   The mold for plastic molding according to claim 1, wherein the coating layer is a nickel plating layer formed by electroless plating.   2. The plastic molding die according to claim 1, wherein the coating layer is a mixture layer of nickel and fluororesin formed by electroless plating.   The mold for plastic molding according to claim 1, wherein the coating layer is any one of a titanium nitride film, a titanium carbide film, and a titanium carbonitride film.   The mold for plastic molding according to claim 2, wherein a transfer surface of the cavity is constituted by a nickel plating layer of a metal-ceramic composite material.   4. The mold for plastic molding according to claim 3, wherein the surface other than the transfer surface of the cavity is a mixture layer of a metal-ceramic composite material.   5. The plastic molding according to claim 4, wherein the surface other than the transfer surface of the cavity is composed of any one of a titanium nitride film, a titanium carbide film, and a titanium carbonitride film of a metal-ceramic composite material. Mold.   6. The mold for plastic molding according to claim 2, wherein the nickel plating layer has a thickness of 20 μm or more.   The plastic mold according to claim 3 or 6, wherein the mixture layer has a thickness of 20 µm or less.   The plastic molding die according to claim 4 or 7, wherein any one of the titanium nitride film, the titanium carbide film, and the titanium carbonitride film has a thickness of 10 µm or less.   10. The mold for plastic molding according to claim 3, 6 or 9, wherein the fluorine resin in nickel in the mixture layer is 10 to 30% by volume.   12. The metal mold for plastic molding according to claim 1, wherein the metal-ceramic composite material includes ceramic powder or ceramic fiber as a reinforcing material and aluminum or an aluminum alloy as a matrix.   The plastic molded product shape | molded with the metal mold | die for plastic molding as described in any one of Claims 1-12. An optical scanning device or an optical device incorporating the plastic molded product according to claim 13.

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