JP4787549B2 - Resin substrate for resin reflector and method for producing the same - Google Patents

Description

  The present invention relates to a resin molded article containing an inorganic filler as a substrate of an optical reflector and a method for producing the same.

  Optical reflectors used in various optical devices are required to be lighter, have higher reflectivity, and have higher accuracy as the apparatus becomes larger, while being required to have strength and heat resistance. In order to meet these requirements, particularly weight reduction, a substrate in which a base material is made of an inorganic fiber-filled resin and a metal film such as aluminum is deposited on the surface is often used.

The base material of the resin reflector is generally manufactured by injection or compression molding of a thermoplastic resin or a thermosetting resin. This injection molding is a process in which a mold cavity polished in a mirror shape with a predetermined shape is filled with heat-melted resin, cooled, solidified, and taken out of the mold. The surface of the product (in this case, the reflector substrate) has flow marks, warpage, deformation, sink marks due to resin shrinkage, or gas generated from reinforcing fillers such as inorganic fibers, resulting in poor gloss on the surface of the molded product. Since a glossy surface cannot be obtained, it has been a problem that good optical reflectance cannot be obtained despite the metal film deposition.

Thus, since the surface property of the resin molded product is not good, other means are often added to the production of the resin reflecting mirror. For example, a. There is a configuration in which a transfer sheet in which a metal film layer is formed is inserted into a cavity of a resin reflecting mold, the resin is injected into the mold, and the resin and the transfer sheet are integrated. (Patent Document 1). Although this method is low in cost, there is a problem that the quality is not stable because the transfer resin is deformed and stretched by the molten resin flowing in the mold.

B. A metal vapor-deposited film in which a metal vapor-deposited layer, a bright pigment layer, and an adhesive layer are laminated on one side of a plastic film is inserted into an injection mold, and this is heated and vacuum sucked to adhere to the cavity surface. And a resin reflecting mirror is obtained by injection molding a molten resin (Patent Document 2). In this method, a vacuum pump is necessary in addition to the injection molding machine, and the film sucked by the vacuum is stretched unevenly, which may cause uneven reflection performance.

C. A sheet material made of a metal plate and a resin is sequentially laminated on at least one surface of a fiber reinforced plastic substrate formed by injection molding via an adhesive, or a sheet made of a metal plate and a resin is bonded to a prepreg via an adhesive. -Tote materials are laminated in order and integrated by post-molding (Patent Document 3). This resin reflecting mirror has a drawback in that it requires a metal plate for concealing the surface roughness of the resin base material and requires a pre-process for processing this into a predetermined shape, leading to high costs.

And d. At least a vapor deposition film in which a vapor deposition film layer, which is a mirror-like reflection surface, is formed on the surface of the resin layer, and a laminated structure in which a reinforced resin layer is laminated on the back surface of the resin layer constituting the vapor deposition film. A method of thermocompression bonding a vapor deposition film and a reinforced resin layer while transferring the shape of the surface is disclosed (see Patent Document 4). In this method, the base material is formed of a reinforced resin. However, since the non-reinforced resin layer and the deposited film layer are laminated on the surface, there is a problem with the heat resistance of the non-reinforced resin layer. May occur.

In injection molding of a thermoplastic resin optical reflection member having at least one optical reflection surface, a hollow portion is formed in the optical reflection member by introducing a heating fluid of 3.5 × 10 ⁶ kgf / cm 2 -G. Some of them are designed to reduce the sink on the surface of the molded product and improve the transferability of the cavity mirror surface. This molding method uses what is called a gas assist method or a gas counter pressure method that is used to suppress foaming of the surface of a molded product in the molding of a foamed resin, and gas of 200 psi to 300 psi in the cavity. Pressure is applied (US Patent 3268635).
JP-A-06-182783 JP-A-10-204201 JP 11-264906 A JP 2004-188733 A JP 2001-105449 A

Along with the increase in size of optical equipment, the size of optical reflectors is naturally increasing, and weight reduction, improvement in heat resistance and reflectivity, and reduction in cost are required. Therefore, it is desirable to stably produce a glossy product with a small surface roughness even in a resin reflector base material, but the quality is the type of resin, the melting temperature of the resin, the molding pressure, the gold It is affected by various conditions such as resin flow in the mold, mold temperature, cooling, and the like, and it is a problem to combine optimum conditions and to stabilize the quality during use as a reflector.

As a result of sincerity research, the developer shows that the reflectance of resin reflectors varies depending on the temperature conditions during use. Therefore, if the linear expansion coefficient is reduced by proceeding with crystallization of the molded product, a stable resin can be obtained. It was found that a reflector made of light was obtained. Accordingly, in the first aspect of the present invention, the resin-made optical reflector substrate having an optical reflecting surface has at least one cavity surface with a surface roughness Ra of 5 nm or less, and the cavity surface and the cavity surface. Both opposing cavity surfaces are made of the same material, and both are held at approximately the same temperature in the range of 120 to 200 ° C. during injection molding. Further, gas or air is introduced into the cavity in advance to reduce the internal pressure to 0.6 to A mold held at 1.0 MPa or less is used, and a crystalline resin is injected and filled into the mold cavity and molded to a linear expansion coefficient of 18 ppm / ° C. or less.

According to a second aspect of the present invention, in the resin-made optical reflector substrate molding die, the gate shape as the flow path of the molten resin is a fan shape.

According to a third aspect of the present invention, in the resin-made optical reflector substrate molding die, the fixed and movable cavity surfaces are formed of the same material, that is, zirconia, or steel hardened to a hardness of HRc 63 to 75. The surface roughness is polished to Ra 5 nm or less.

According to a fourth aspect of the present invention, in the resin-made optical reflector substrate molding die, the cavity surface on the fixed side and the movable side is constituted by a zirconia insert having a thickness T = 10.0 mm or more and 50.0 mm or less. It is characterized by being.

According to a fifth aspect of the present invention, the resin-made optical reflector substrate having an optical reflecting surface on at least one surface thereof is a PPS resin, a cyclic olefin-based transparent resin, an epoxy thermosetting resin, or an aromatic polyester. Alternatively, the resin is filled with 20 to 50% of an inorganic material that becomes a spherical body having an average particle diameter of 18 nm or less.

In the mold, injection molding of molten resin mixed with spherical inorganic filler in a state where the gate as the flow path of the molten resin has a fan shape and the cavity internal pressure is increased to 0.6 to 1.0 MPa. Therefore, the generation of gas from the resin is prevented, and further, the transferability of the cavity surface is improved, and a molded product with very little sink, warpage, and distortion can be stably produced without causing haze. Moreover, the cavity temperature promotes the crystallization of the resin, and thus a molded article (base material) having a small linear expansion coefficient can be applied to a metal vapor deposition film such as a surface aluminum of the optical reflector base material by 0.2 μm to When formed to a thickness of 0.5 μm, a reflectance of 90 to 96% is obtained.

In a resin optical reflector, a resin film is coated with a metal film by vapor deposition or the like to form a reflection surface. What is important is the surface roughness and gloss of the substrate surface. The surface of the substrate is formed by transferring the cavity surface of the injection mold, but the molding machine performance, mold structure, resin type and melting temperature, injection pressure, holding pressure, etc. It is best to satisfy the following conditions.

The injection molding machine is equipped with a plastic plastic (injection cylinder with an injection plunger, and a plasticizing cylinder with a plasticizing screw or plunger. The resin melted in the plasticizing cylinder is quantitatively fed into the injection cylinder. One that injects this resin) or one provided with an air vent was used.

For the mold 1, the same material obtained by polishing the cavity surface for transferring the reflecting surface of the optical reflector and the cavity surface forming the back surface thereof, that is, the opposite cavity surfaces 2 and 2 to a surface roughness Ra of 5 nm or less, such as zirconia ( Or steel) (FIG. 1), and the temperature of the cavity surface during injection molding is set to substantially the same temperature.

The distance between the opposing mold cavity surfaces is 1.0 mm to 1.2 mm, and the gate 3 serving as a resin flow path to the cavity is a fan gate.

Prior to injecting the molten resin with an injection molding machine, air or nitrogen gas having a gauge pressure of 0.6 MPa to 1.0 MPa or less was introduced P into the cavity C of the mold to increase the pressure. In the present invention, since it is not molding of a foamed resin, it was kept at a lower pressure than the gas pressure that is controlled by the conventional gas counter pressure method.

The resin for molding is PPS, a cyclic olefin-based transparent resin, an unsaturated polyester resin, a phenol resin, which is filled with a spherical inorganic filler having a diameter of 5 nm or less, and is sufficiently pre-dried.

Examples of inorganic fillers include glass, asbestos, carbon, silica alumina, titanium oxide, calcium carbonate, calcium phosphate, calcium sulfate, calcium silicate, magnesium oxide, calcium phosphate, silicon nitride, glass beads, zirconium oxide, and carbon black. However, the molded article (reflecting mirror substrate) required in the present invention has a small surface roughness and a high heat resistance, and the shape of the inorganic filler is preferably spherical.

As the substrate 10 of the optical reflector, flat plates of 30 mm × 30 mm × 1 mm, 1.2 mm, and 1.5 mm were molded by PPS (Fortron 8670A64, manufactured by Polyplastics Co., Ltd.) (see FIG. 2). The injection molding machine is Sodick TR40VR (prep plastic type), cylinder temperature: 300-340 ° C (changes in increments of 10 ° C), mold temperature: 60-200 ° C (changes in increments of 10 ° C), injection speed: 50-300 ° C / Sec (variation in increments of 50 mm / sec), holding pressure: 170 MPa, holding pressure time: 10 sec, cooling time: 10 sec.

The PPS is selected from a grade filled with 30% by weight glass beads (particle size of 18 μm or less, preferably 10 μm or less) based on the resin, and pre-dried at 200 ° C. for 4 hours (generally at 140 ° C. for 3 hours). Time).

The mold was made of carbon steel, a heater was embedded in order to maintain the mold temperature, and a 30 mm zirconia plate was polished to Ra: 5 nm or less and mounted on the opposing cavity surface. In addition, the gate as a resin flow path to the cavity was an edge gate, a disk gate, and a fan gate, and the effectiveness of forming an overflow portion at the flow front of the resin in the cavity was confirmed. The results are shown in Table 1, but the data was deleted because there was a lot of haze in the molded product with the edge gate formed on the side. The installation of the overflow is unnecessary because any gate causes haze on the side opposite to the gate. In addition, although there is no large difference in the amount of haze generated between the fan gate and the disk gate, the fan gate has the least amount of sink marks. Table 2 shows the surface roughness and glossiness of the substrates molded with resins (referred to as RSF-10257 and RSF-10258) in which glass beads having a particle diameter of 10 nm and 15 nm are mixed and strengthened in the same material as the PPS, respectively. It was shown to.

Next, regarding the method of injection molding into a cavity kept in vacuum and the method of pre-pressurizing the inside of the cavity with nitrogen gas or air and injection molding the molten resin there, the molding machine, mold, etc. The following molding conditions were used. In the experiment, air with a gauge pressure of 0.6, 0.8 and 1.0 MPa was introduced into the mold and injection molding was performed. As described above, the molding resin is PPS filled with 30% by weight of glass beads, and is almost completely at a high temperature of 200 ° C. for 4 hours before molding (general pre-drying is about 140 ° C. for about 3 hours). Or it could be said that it was excessive.

The evacuation in the cavity is a pipe placed at the end of the resin flow in the cavity and depressurized by a vacuum pump. Pressurization is the use of the so-called gas counter pressure method in which air of the above pressure is introduced from this pipe. . The molding using the vacuum drawing produced stick slip on the surface of the molded product, but the stick slip was reduced in the case of the gas counter pressure method in which the cavity pressure was increased by air. Further, in the molding by the gas counter pressure method using the pre-plastic type injection molding machine, both the haze and the stick slip decreased, and a molded article having a good gloss was obtained. In addition, although it was examined whether to provide an air vent at the flow end of the resin in the cavity, no relationship with stick slip was found.

In addition, when comparing the glossiness of glossy surfaces (using digital declination gloss meter UGV-4D Suga Test Instruments Co., Ltd.) with respect to molded products having thicknesses of 1.0 mm, 1.2 mm and 1.5 mm, 1 0.0 mm was the best. For example, the substrate is molded as cylinder conditions: 330 ° C., mold temperature: 180 ° C., injection speed: 150 mm / sec, holding pressure: 170 MPa, cooling time: 10 sec, air counter pressure: 0.8 MPa. The glossiness of the glossy surface (Suga glossiness meter as 100) was 161.7%.

When an aluminum film was deposited on a 1.0 mm molded product obtained by the above fan gate, a light reflectance of 95% or more was obtained.

When the relationship between the injection molding conditions and the surface roughness of the molded product was examined, the mold temperature: 160 to 180 ° C., the cylinder temperature of the injection molding machine: 180 to 330 ° C., the injection speed of the molten resin: 150 mm / sec. In addition, it was found that the best surface roughness can be obtained by setting 300 mm / sec, holding pressure: 130 to 170 MPa, holding pressure time: 10 to 20 sec, and cooling time: 10 to 20 sec.

In order to stably obtain a good mirror surface as an optical reflector substrate, it is necessary to keep the cavity temperature stable. In the mold, the thickness of the zirconia constituting the fixed side and movable side cavity surfaces is set to 10, 20, 30, 40, 50 mm, and the temperature is controlled, and then injection molding is performed, and the haze and stick of the molded product surface Slip and gloss were observed. As a result, the preferable thickness T of zirconia was 30.0 mm. When this mold is molded at the above-mentioned mold temperature of 160 to 200 ° C., the crystallization temperature is maintained for a long time, so that the crystallization of the molded article proceeds and at the same time the linear expansion coefficient becomes small (based on JIS K6911). Measurement). Even at the best zirconia thickness of 30.0, the surface gloss of the molded product varied due to unstable cavity temperature from the first shot at the start of injection molding to about 40 shots.

Next, it shape | molded by the said metal mold | die, without adding an inorganic filler to cyclic olefin type transparent resin (Topas 6015S-04: Mitsui Petrochemical Co., Ltd. product). The molding conditions were as follows: cylinder temperature: 300 ° C., mold temperature: 130 ° C., injection speed: 20 mm / sec, holding pressure: 75 MPa, cooling time: 30 sec. It was better than Example 1.

Further, a substrate made of a phenol resin (manufactured by Sumitomo Bakelite Co., Ltd .: PM-9610) as a thermosetting resin was prepared, and as a comparative example, three types of phenol resin under development and trial use were injected using the mold of Example 1 above. Molded. Molding conditions and the like in this case were as follows: mold temperature: 180 ° C. (both movable and fixed side), cylinder temperature: 80 ° C./40° C., injection time: 8 seconds, curing time: 40 seconds. Various properties of the obtained molded product are shown in Table 3.

The measuring method of the said table | surface is as follows.
Surface roughness measurement A: Interferometric surface roughness measuring machine (scanning range: 1.5 × 1.1 mm)
Surface roughness measurement B: Contact type surface roughness measuring machine (scanning distance: 8 mm in the flow direction)
Flatness measurement: Rmax was determined by measuring 5 × 5 points on a flat plate with a three-dimensional side machine.
Linear expansion coefficient: measured based on JIS K6911.

In the reflecting mirror in which the same aluminum film as described above was vapor-deposited on the base material made of the thermosetting resin, an optical reflectance of about 95% was obtained at an operating environment temperature of the optical device with an average linear expansion coefficient of 18 PPM / ° C. It was a thing. As described above, the reflecting mirror expands and contracts due to fluctuations in temperature conditions during use, and the reflectance varies accordingly. Therefore, the property required for the base material of the reflecting mirror is, of course, surface gloss, but the linear expansion coefficient is small and the influence of temperature is small.

In an optical reflector that is required to be lighter and stronger, it is desired to use a resin having a small specific gravity. The optical reflecting mirror substrate of the present invention is a thin type molded with a resin filled with a spherical inorganic material by nesting mirror-polished zirconia on the cavity surface of the mold and introducing a low-pressure gas counter pressure here. In addition, it is possible to obtain excellent performance in terms of surface glossiness, reflectance, etc., and furthermore, because high reflectance can be maintained by keeping the linear expansion coefficient small, it can be used in various optical instruments. is there.

It is a schematic diagram of a metal mold | die. It is an example of the reflector base material shape | molded by the fan gate.

Explanation of symbols

1 mold 2 nesting 3 fan gate 10 substrate

Claims (5)

In a manufacturing method by injection molding of a resin-made optical reflector substrate having an optical reflecting surface on at least one surface thereof,
At least one of the cavity surfaces has a surface roughness Ra of 5 nm or less, and both the cavity surface and the opposite cavity surface are made of the same material, and these cavity surfaces are both within the range of 120 to 200 ° C. during injection molding. is kept approximately the same temperature and further, the internal pressure using a mold maintained at 0.6 or more 1.0MPa or less by introducing gas or air in advance within the cavity, the average particle size within the mold cavity is 18nm the following inorganic material made of spherical bodies 20 to 50% loading molten resin injected and filled, the linear expansion coefficient (average) 18 ppm / ° C. the method for manufacturing an optical reflecting mirror substrate, characterized by forming below. Injection mold plastic optical reflector substrate is, the manufacturing method of the optical reflector substrate of claim 1, wherein the gate shape as a flow path of the molten resin is a fan type. An injection mold for molding a plastic optical reflector base material is made of a steel whose fixed and movable cavity surfaces are made of the same material and hardened to a hardness of HRc 63 to 75, and has a surface roughness Ra of 5 nm or more. 2. The method for producing an optical reflector substrate according to claim 1, wherein the substrate is polished as follows. The mold for molding a resin optical reflector base material is characterized in that the cavity surfaces on the fixed side and the movable side are constituted by zirconia inserts having a thickness T = 10.0 mm or more and 50.0 mm or less. Item 4. A method for producing an optical reflector substrate according to Item 3. Plastic optical reflector substrate having optical reflective surface at least on its one surface, PPS resin, optical of claim 1, wherein the cyclic olefin-based transparent resin, phenolic resin or unsaturated polyester A method for manufacturing a reflector substrate.

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