JP5045221B2 - Mold assembly and injection molding method - Google Patents

Description

  The present invention relates to a mold assembly, an injection molding method using the mold assembly, and a molded product obtained by the injection molding method.

  In a generally used injection molding method or injection compression molding method, in order to improve the transferability of a molded product made of a thermoplastic resin, the mold temperature, the resin temperature, and the mold internal pressure are usually increased. It is also known that the injection compression molding method can improve the transferability of the entire molded product because the internal pressure can be applied more uniformly to the entire molded product than the injection molding method.

  In the injection molding method and the injection compression molding method, the molded product is often warped. In order to suppress the occurrence of warping, it is more effective to adopt the injection compression molding method than the injection molding method because the distortion of the molded product can be reduced. By the way, one of the factors that cause distortion in the molded product is that the molten thermoplastic resin that contacts the surface of the mold cavity (referred to as the mold cavity surface) is rapidly cooled and solidified. Can be mentioned. The cause of the rapid cooling and solidification of such a molten thermoplastic resin is that the mold is made of a steel material.

  When the uneven portion provided on the cavity surface of the mold is transferred to the surface of the molded product, if the uneven shape is large to some extent, the transfer can be performed depending on the forming conditions even under general molding conditions. However, when the uneven portion to be formed on the molded product becomes smaller or deeper, it becomes difficult to faithfully transfer the uneven portion provided on the cavity surface of the mold to the surface of the molded product. . This is also because the mold is made of steel. In general, in order to improve transferability, it is necessary to force the thermoplastic resin against the cavity surface of the mold in a molten state as much as possible. However, because steel has high thermal conductivity, the molten thermoplastic resin begins to solidify as soon as it comes into contact with the cavity surface of the mold, and a solidified layer is formed. There is a problem that even if pressure is applied to the plastic resin, the fine irregularities cannot be transferred to the molded product.

  For example, Japanese Patent Laid-Open No. 8-318534 discloses a molding having an excellent appearance by using a material with low thermal conductivity for nesting to suppress quenching and solidification of a molten thermoplastic resin injected into a cavity. A method of forming an article has been proposed. Here, the nesting is made of ceramics or glass.

  Japanese Unexamined Patent Publication No. 5-38721 discloses a synthetic resin molding die in which a thin layer made of ceramics or cermet is formed on the cavity surface of the die. This thin layer is formed by a thermal spraying method in which many voids are intentionally generated for the purpose of improving heat insulation. Such a thin layer is hereinafter referred to as a ceramic sprayed layer for convenience. This ceramic sprayed layer may not be dense and is not easily damaged by heat or pressure.

  In Example 5 of Japanese Patent Application Laid-Open No. 2004-175112, there is disclosed a nesting 25 constituted by a nesting body 26 made of stainless steel, a heat insulating layer 27, and a sealing layer 28. The heat insulating layer 27 is formed on the nested body 26 by a plasma powder spraying method using zirconia ceramic material powder. On the other hand, a sealing layer 28 is formed on the surface of the heat insulating layer 27 by Ni-P electroless plating.

JP-A-8-318534 Japanese Patent Laid-Open No. 5-38721 JP 2004-175112 A

By the way, in the technique disclosed in Japanese Patent Application Laid-Open No. 8-318534, the nesting is made of a dense but brittle material. The plate is pressed with a specific clearance, and measures are taken to protect the edge of the nesting that is easily damaged. However, it may be difficult to arrange the metal plate due to the structure of the mold, the shape of the cavity, the molded product, or the like. In addition, since the insert made of a sintered body obtained by the firing method has a dense structure, it is very easy to obtain _a surface roughness _Ra of 0.05 μm or less when lapping is performed. . However, since the density of the nesting is high, using the nesting in a portion where tensile stress is applied has a drawback that the nesting is easily damaged. Furthermore, in general, since it is difficult for a sintered body to limit the sintering furnace and to suppress deformation during firing, a sintered body having a size exceeding the B5 (about 470 cm ² ) size is produced. This is difficult, and forming a curved surface or drilling a ceramic sintered body with high hardness is one of the highly difficult processes. If time and cost are spent, it is possible to produce a sintered body having a simple shape of about 10 cm square, but it is often difficult to produce a sintered body having a larger shape than that.

  Moreover, when forming an uneven | corrugated | grooved part in the molded article surface, it is necessary to provide an uneven | corrugated | grooved part in the surface (nested cavity surface) which comprises the cavity of a nest | insert. However, since ceramics and glass are hard and excellent in chemical resistance, it is extremely difficult to provide an uneven portion on the cavity surface of the insert. Furthermore, when changing the pattern of the concavo-convex portion depending on the molded product, a nesting must be made each time, resulting in an increase in manufacturing cost of the molded product.

  In addition, as a method of suppressing the cooling of the molten thermoplastic resin in the cavity, a method of disposing a resin material having a low thermal conductivity inside the mold has also been proposed. There is a problem in that the fine irregularities provided on the material are deformed and the durability is poor. Although it has been proposed to form a metal film on the surface of such a resin material to prevent the deformation of fine irregularities, the resin material itself may be deformed, or the metal film and the resin material There is a problem in that scratches are generated at the interface of the film, and even the scratches are transferred to the surface of the molded product.

  In the technique disclosed in JP-A-5-38721, although quenching of the molten thermoplastic resin injected into the cavity can be suppressed, there are many voids on the surface of the ceramic sprayed layer. When molten thermoplastic resin penetrates into the gap and the molded product is released from the mold, the ceramic sprayed layer is destroyed or many irregularities are transferred to the surface of the molded product, making it impossible to obtain a high-quality molded product. Have a problem. It is also disclosed that a very thin (several μm) silicone-based paint is applied to flatten the surface of the ceramic sprayed layer, but a problem with durability tends to occur.

  In the insert 25 disclosed in Example 5 of Japanese Patent Application Laid-Open No. 2004-175112, the sealing layer 28 is formed by an electroless plating method. Generally, the heat insulating layer 27 is formed by a thermal spraying method. Since there are many voids, the following problems are likely to occur when the sealing layer 28 is formed by the electroless plating method. That is, when there are many deep voids in the heat insulating layer 27, the plated layer grows while entraining hydrogen bubbles generated in the plating step, and as a result, pinholes are likely to occur frequently in the sealing layer 28. In particular, the adhesion force of the sealing layer 28 to the heat insulating layer 27 is reduced due to a large pinhole generated in a large portion of the void or the influence thereof. Then, a problem that the pinhole generated in the sealing layer 28 is transferred to the surface of the molded product, or a part of the molded product enters the pinhole generated in the sealing layer 28, and the molded product is released from the mold. At this time, the problem that the sealing layer 28 is damaged is likely to occur.

Accordingly, an object of the present invention is composed of a metal block and a thermal spray coating, has high durability, can be manufactured regardless of whether it is flat or curved, and, for example, has an area of B5 size or more (specifically, Has a nest that can be produced even with a large area of, for example, 500 cm ² or more, and can give a desired shape to the surface of the molded product (for example, a fine uneven portion can be easily and stably formed). Another object of the present invention is to provide a mold assembly (which can be transferred to the surface of the molded article), an injection molding method using the mold assembly, and a molded article obtained by the injection molding method.

In order to achieve the above object, a mold assembly of the present invention comprises:
(A) A first mold part, a second mold part, and a molten resin injection part provided in the first mold part, and a cavity formed by clamping the first mold part and the second mold part. Mold formed,
(B) Nesting disposed in the first mold part and / or the second mold part, and
(C) a metal film having a thickness of 0.03 mm to 0.5 mm disposed on the surface of the nest, forming a surface constituting the cavity;
A mold assembly comprising:
Nesting is
(A) metal block,
(B) a metal underlayer having a thickness of 0.03 mm to 1 mm formed on at least the surface of the metal block facing the cavity; and
(C) a thermal spray coating made of ceramics formed on a metal underlayer;
Consists of
The thermal spray coating has a porosity that varies in the thickness direction,
The porosity is characterized by a lower value closer to the surface of the sprayed coating.

An injection molding method according to the first aspect of the present invention for achieving the above object is an injection molding method using the mold assembly of the present invention,
(A) After the first mold part and the second mold part are clamped to form a cavity, the molten thermoplastic resin is injected into the cavity from the molten resin injection part,
(B) Cooling and solidifying the thermoplastic resin in the cavity, and then releasing the obtained molded product from the mold,
It comprises the process.

An injection molding method (injection compression molding method) according to a second aspect of the present invention for achieving the above object is an injection molding method using the mold assembly of the present invention including the above preferred configuration. ,
(A) After the first mold part and the second mold part are clamped so that the volume of the cavity is larger than the volume of the molded product to be molded, the molten thermoplastic resin is cavityd from the molten resin injection part. Injecting into,
(B) Simultaneously with the start of injection of the molten thermoplastic resin, during injection, at the same time of completion of injection, or after completion of injection, the volume of the cavity is reduced to the volume of the molded product to be molded;
(C) Cooling and solidifying the thermoplastic resin in the cavity, and then releasing the obtained molded product from the mold,
It comprises the process.

  In the injection molding method according to the second aspect of the present invention, in the step (b), at the same time as the start of the injection of the molten thermoplastic resin, during the injection, at the same time as the completion of the injection, or after the completion of the injection, the cavity If the start of volume reduction coincides with the start of injection of the molten thermoplastic resin, the end of the volume reduction is performed during the injection of the molten thermoplastic resin or the injection. When the start of volume reduction is during injection of molten thermoplastic resin, the end of volume reduction may be at the same time as completion of injection or after completion of injection. In the case where the start of the volume reduction is made simultaneously with the completion of the injection of the molten thermoplastic resin, the end of the volume reduction can be made after the completion of the injection.

  In the injection molding method according to the first aspect to the second aspect of the present invention, a solid molded product can be molded.

  Alternatively, in the injection molding method according to the first aspect to the second aspect of the present invention, a mold assembly further including a pressurized fluid injection nozzle communicated with the cavity is used, and the first aspect of the present invention is used. In the aspect (1), in the step (a), the molten thermoplastic resin is injected into the cavity while injecting the molten thermoplastic resin into the cavity from the molten resin injection part, or at the same time as or after the completion of the injection. Injection of the pressurized fluid into the thermoplastic resin from the pressurized fluid injection nozzle can be started. On the other hand, in the second aspect of the present invention, in the step (b), at the same time as the end of the volume reduction or the volume. After completion of the reduction, the injection of the pressurized fluid can be started from the pressurized fluid injection nozzle into the molten thermoplastic resin injected into the cavity. Such an injection molding method in which a pressurized fluid is injected may be referred to as a gas assist molding method. By adopting the gas assist molding method, a molded product having a hollow portion can be obtained. When the gas assist molding method is adopted, the amount of the molten thermoplastic resin injected into the cavity may be an amount that completely fills the cavity (a so-called full shot method) or an amount that is incompletely filled. It may be present (so-called short shot method). The pressurized fluid is a gas substance at normal temperature and normal pressure, and preferably does not react or mix with the thermoplastic resin used. Specific examples include nitrogen gas, air, carbon dioxide gas, helium and the like, and nitrogen gas and helium gas are preferable in consideration of safety and economy. For example, the pressurized fluid injection nozzle may be disposed in the first mold part, may be disposed in the second mold part, or both the first mold part and the second mold part. You may arrange in. The pressurized fluid injection nozzle is positioned in the first mold so that the tip of the pressurized fluid injection nozzle is located in the cavity or in the vicinity of the surface constituting the cavity of the first mold part or the second mold part. It is preferable to arrange in the part or the second mold part. The rear end portion of the pressurized fluid injection nozzle is connected to a pressurized fluid source via, for example, a pipe. A moving means is attached to the rear of the pressurized fluid injection nozzle. Alternatively, the pressurized fluid injection nozzle may be arranged such that the tip of the pressurized fluid injection nozzle is disposed in the molten resin injection portion, and the mold assembly is an injection provided with an injection cylinder. It is attached to the molding machine, the injection cylinder and the molten resin injection part are in communication, and pressurized fluid injection is performed so that the pressurized fluid injection nozzle is placed at the tip (nozzle part) of the injection cylinder It is good also as a structure which arrange | positions a nozzle.

  The mold assembly of the present invention, and the injection molding method according to the first to second aspects of the present invention including the preferred embodiments described above (hereinafter, these may be collectively referred to simply as the present invention) In this case, a sprayed coating can be formed on the entire surface of the metal block facing the cavity, or a sprayed coating can be formed on a part of the surface of the metal block facing the cavity. It can also be made into the form currently performed.

  In the present invention including the preferred configurations and forms described above, the thermal spray coating that is a coating formed by thermal spraying may be composed of the same composition from the viewpoint of composition (referred to as the same composition coating for convenience). A gradual coating film in which the composition of the thermal spray material is continuously changed between the layers can also be used. In addition, the sprayed coating may be composed of a single layer (referred to as a single-layer sprayed coating) from the viewpoint of the change in porosity, or from a multilayer structure of multiple layers (for convenience, each layer is referred to as a unit layer). It may be configured. The composition of each of the plurality of unit layers may be the same or different. Further, as described above, the thermal spray coating has a porosity changed in the thickness direction, but the state of the porosity change gradually (continuously from the interface between the metal underlayer and the thermal spray coating toward the surface of the thermal spray coating. (A) may be reduced, may be reduced stepwise, or may be gradually (continuously) reduced stepwise. When the thermal spray coating is composed of a single-layer thermal spray coating having the same composition or a gradually changing coating, it is possible to obtain a thermal spray coating having a porosity changed in the thickness direction depending on the thermal spraying conditions and the like. Further, when the thermal spray coating is constituted by a laminated structure of a plurality of unit layers, the porosity in each of the unit layers constituting the laminated structure of the plurality of layers can be varied depending on the thermal spraying conditions or the like.

  In the present invention including the preferred configurations and forms described above, the thermal conductivity of the thermal spray coating is 1 W / (m · K) to 4 W / (m · K), and the average thickness of the thermal spray coating is 0. It is preferable that the thickness is 3 mm to 2.0 mm.

  When the thermal conductivity value of the thermal spray coating is below the lower limit of the above range, it may be difficult to obtain a desired porosity of the thermal spray coating. On the other hand, when the thermal conductivity value of the thermal spray coating exceeds the upper limit of the above range, for example, it becomes difficult to suppress quenching of the molten thermoplastic resin in contact with the thermal spray coating through the metal film. There exists a possibility that the external appearance improvement effect of the obtained molded article may reduce. The thermal conductivity of the thermal spray coating can be measured based on a method such as a laser flash method or a hot wire method.

  Also, for example, in order to suppress the rapid cooling of the molten thermoplastic resin in contact with the thermal spray coating through the metal film and to improve the appearance of the molded product, when the thermal spray coating is composed of a single-layer thermal spray coating, the average thickness of the thermal spray coating As described above, the thickness is preferably 0.3 mm to 2.0 mm, preferably 0.3 mm to 1.0 mm. On the other hand, when the thermal spray coating is composed of a laminated structure of a plurality of unit layers, the average thickness (total thickness average) of the thermal spray coating is 0.5 mm to 1.8 mm, preferably 1.0 mm to 1.5 mm. It is desirable that the average thickness of the unit layer (sometimes referred to as a top coat) constituting the surface of the sprayed coating is 0.05 mm to 0.3 mm, preferably 0.1 mm to 0.2 mm. The average thickness of the unit layer (sometimes referred to as an intermediate layer) is 0.1 mm to 0.5 mm, preferably 0.2 mm to 0.4 mm, and the number of unit layers is 2 to 4, preferably 2 to 3. The thickness (film thickness) of the thermal spray coating is applied to the cut cross section by polishing or lapping as necessary, and the cross section is measured with a digital microscope, optical microscope, scanning electron microscope (SEM), laser microscope, etc. It can be measured based on the method of observing and measuring the thickness.

Furthermore, in the present invention including the preferred configurations and forms described above, in a portion up to a thickness of 0.05 mm from the surface of the thermal spray coating toward the inside of the thermal spray coating (referred to as the surface region of the thermal spray coating for convenience). The average value of the porosity is 0.4% or more and less than 5%, and the portion from the interface between the metal base layer and the thermal spray coating to the thickness of 0.2 mm (referred to as the bottom region of the thermal spray coating for convenience). The average porosity is preferably 5% or more and 10% or less. When converted into the average porosity calculated from the apparent density, the average porosity in the surface area of the sprayed coating is 3% or more and less than 10%, and the average porosity in the bottom area of the sprayed coating is 10% or more and 20%. % Or less. Alternatively, the average particle diameter of the material constituting the thermal spray coating in the portion (surface region of the thermal spray coating) having a thickness of 0.05 mm from the thermal spray coating surface toward the inside of the thermal spray coating is 2 × 10 ⁻⁶ m (2 μm) or more. 5 × 10 ⁻⁵ m (50 μm), a material that forms the thermal spray coating in the portion (bottom region of the thermal spray coating) up to a thickness of 0.2 mm from the interface between the metal base layer and the thermal spray coating toward the inside of the thermal spray coating The average particle size of is preferably 2 × 10 ⁻⁵ m (20 μm) to 1 × 10 ⁻⁴ m (100 μm).

  The average particle size of the material constituting the thermal spray coating in the surface area of the thermal spray coating is desirably as small as possible, but if it is too small, it is difficult to convey the raw material powder (ceramic particles) in the thermal spraying process for forming the thermal spray coating. There is a risk of becoming. Therefore, from the viewpoint of facilitating the formation of the sprayed coating or preventing the occurrence of cracks in the sprayed coating, the surface of the sprayed coating from the raw material powder (ceramic particles) having an average particle diameter in the above range. It is preferable to constitute a region. On the other hand, the average particle size of the material constituting the thermal spray coating in the bottom region of the thermal spray coating is within the above range, achieving the desired porosity and improving the heat insulation, and the influence of unevenness on the surface of the thermal spray coating. Further, it is preferable from the viewpoint of not generating cracks in the sprayed coating.

  Here, the average particle size is defined as a particle size at which the cumulative particle size of the powder is 50%, and can be measured based on, for example, a light transmission sedimentation method.

Also, various preferred configurations described above, in the present invention including the embodiment, the surface roughness R _a of the sprayed coating surface is desirably 0.05μm or less. The surface roughness _Ra is defined in JIS B 0601: 2001. The surface of the thermal spray coating is mirror-wrapped with fine diamond abrasive grains, and the surface of the thermal spray coating is measured using a surface roughness meter. The average roughness of the center line from the roughness curve data obtained by scanning several times under the conditions of at least a magnification of 20000 times, a reference length of 0.8 mm, a cutoff of 0.8 mm, and a measurement speed of 0.05 mm / sec. Measurement can be performed based on a method of selecting (R _a ) and obtaining an average value thereof. Here, as described above, by setting the porosity average value in the surface area of the thermal spray coating within the above range, the thermal spray coating surface becomes a very dense surface state, for example, the surface of the thermal spray coating after lapping The surface roughness _Ra can be easily reduced to 0.05 μm or less. If the porosity exceeds the upper limit of the above range, fine irregularities remain on the surface of the sprayed coating even after lapping, for example, the irregularities are transferred to the surface of the molded product, resulting in a slight haze in the appearance of the molded product. There is a fear. On the other hand, it is technically difficult to make the porosity less than the lower limit of the above range. The lapping process can be performed using, for example, diamond powder, chemical polishing liquid, or the like, and the number of abrasive particles may be 5000 or higher as the final finish. Further, by making the surface roughness R _a of the sprayed coating surface and 0.05μm or less, for example, a metal film on nesting surface (more specifically, on the sprayed coating surface) removably disposed ( When placed, it is possible to reliably prevent the metal film from being deformed (for example, recessed) by the pressure of the molten thermoplastic resin injected into the cavity.

  In the present invention, the porosity is defined as the ratio of the area occupied by the pores to a certain area in the cross section of the coating, and the average porosity is measured, for example, in the thickness direction of the thermal spray coating. After cutting and obtaining a cross-sectional image with a digital microscope, an optical microscope, a scanning electron microscope (SEM), a laser microscope, etc., the porosity is obtained from the contrast difference of the image using an image analyzer, and further The average value can be obtained from the obtained porosity. In the present invention, the pores that are voids contained in the thermal spray coating include both open pores (open holes) and closed pores (closed holes).

  In the present invention including the various preferable configurations and forms described above, examples of the material constituting the metal block (also referred to as a base) that is the surface to be sprayed of the material include carbon steel and stainless steel. The term metal block includes a metal block made of an alloy.

  The metal underlayer is required to firmly adhere the thermal spray coating to the metal block. As its composition, Ni—Cr, and more specifically, Ni-20% Cr, Ni-50% Cr, Ni Examples thereof include -16% Cr-20% Fe, Ni-19% Cr-6% Al, Ni-55% Cr-2.5% Mo-0.5% B, and the like. The term “metal underlayer” includes an underlayer made of an alloy. If the thickness of the metal underlayer is less than 0.03 mm, it is difficult to obtain strong adhesion to the metal block. On the other hand, if the thickness exceeds 1 mm, peeling occurs at the interface between the metal underlayer and the metal block during spraying of the coating. There is a fear. The upper limit value of the thickness of the metal underlayer is preferably 0.5 mm, more preferably 0.3 mm, and this causes peeling at the interface between the metal underlayer and the metal block during spraying of the coating. This can be reliably prevented, and the durability of the sprayed coating can be improved. The metal underlayer can be formed based on various spraying methods such as a plasma spraying method, an HVOF method, and a spraying method using a wire. The metal underlayer formed based on the thermal spraying method is also referred to as an undercoat spray coating, an undercoat, or a bond coat.

Examples of ceramics constituting the thermal spray coating include zirconium oxide and aluminum oxide. Here, as the composition of zirconium oxide, more specifically, CaO stabilized zirconia (5% CaO—ZrO ₂ , 8% CaO—ZrO ₂ , 31% CaO—ZrO ₂ ), MgO stabilized zirconia (20% MgO). _{-ZrO 2, 24% MgO-ZrO} 2), Y 2 O 3 stabilized zirconia _{(6% Y 2 O 3 -ZrO} 2, 7% Y 2 O 3 -ZrO 2, 8% Y 2 O 3 -ZrO 2, 10% Y ₂ O ₃ —ZrO ₂ , 12% Y ₂ O ₃ —ZrO ₂ , 20% Y ₂ O ₃ —ZrO ₂ ), zircon (ZrO ₂ −33% SiO ₂ ), CeO stabilized zirconia. More specifically, the composition of aluminum oxide is more specifically white alumina (Al ₂ O ₃ ), gray alumina (Al ₂ O ₃ -1.5 to 4% TiO ₂ ), alumina / titania (Al ₂ O _3). -13% TiO _2, Al ₂ O ₃ -20% TiO ₂ , Al ₂ O ₃ -40% TiO ₂ , Al ₂ O ₃ -50% TiO ₂ ), alumina yttria (3Al ₂ O ₃ .5Y ₂ O ₃ ), alumina magnesia (Mg. Al ₂ O ₄ ) and alumina / silica (3Al ₂ O ₃ .2SiO ₂ ) can be mentioned, and particularly preferred is zirconium oxide which can easily control the porosity. However, “%” means% by weight.

The thermal spray coating is formed by a thermal spraying method. Specific examples of the thermal spraying method include a plasma powder spray method and an HVOF method. In order to form a portion having a thickness of at least 0.05 mm from the surface of the thermal spray coating to the inside of the thermal spray coating, the flying speed of the ceramic particles (powder) is preferably 2 × 10 ² m / second or more. . The film thickness during thermal spraying is desirably 1 × 10 ⁻⁴ m (100 μm) / pass or less in order to obtain a dense film. As the thermal spraying device, it is preferable to use a plasma spraying device capable of increasing the flight speed or an HVOF (High Velocity Oxygen Fuel Spraying) device which is a kind of high-speed flame spraying device.

  During thermal spraying, it is desirable to forcibly cool the sprayed material from the front surface and back surface of the sprayed material in order to prevent cracks from being generated in the coating due to thermal expansion due to the generated heat. Compressed air can be used for cooling. In addition, a water cooling block etc. can also be used for cooling from the back surface of a thermal spray. Then, while confirming the state of occurrence of cracks, the test may be performed by changing the cooling conditions as appropriate to determine the optimal cooling conditions.

  In the present invention including various preferred configurations and forms described above, the metal film is preferably made of at least one material selected from the group consisting of chromium, a chromium compound, nickel, and a nickel compound. In this case, the metal film is preferably formed on the sprayed coating by plating. Examples of plating methods include electroplating, electroless plating, chemical plating, or a combination thereof. In this case, the metal film may be formed on the cavity surface of the thermal spray coating, and may be formed on the entire surface of the thermal spray coating, for example.

  Alternatively, in the present invention including the various preferred configurations and forms described above, the metal film is preferably made of a nickel-phosphorus alloy or nickel and is detachably disposed on the surface of the insert.

  In the present invention, a metal film is disposed on the surface of the insert (more specifically, on the thermal spray coating), but what kind of metal film is disposed is determined depending on, for example, a molded product. That's fine. For example, if the metal film is detachably disposed on the surface of the nest (so-called stamper structure), it can be applied only to a molded article having a flat surface, but a large area nest and metal film are low cost. Can be realized. On the other hand, if the metal film is formed on the thermal spray coating by plating, the metal film can be applied to a molded product having a three-dimensional shape (a shape having a three-dimensional curved surface). Higher than.

  In the present invention including the various preferred configurations and forms described above, the surface of the metal film can be a mirror surface, or the surface of the metal film can be uneven. . In addition, as a formation form of the concavo-convex part, a form in which a convex part is formed on the surface of the flat metal film, a form in which a concave part is formed on the surface of the flat metal film, a convex part on the surface of the flat metal film The form with which the combination of the recessed part is formed can be mentioned.

  In the present invention including various preferred configurations and forms described above, as described above, the metal film is preferably made of at least one material selected from the group consisting of Cr, Cr compound, Ni and Ni compound. . The metal film may be composed of one layer or a plurality of layers. Specific examples of the Cr compound include a nickel-chromium alloy. Specific examples of Ni compounds include nickel-iron alloys, nickel-cobalt alloys, nickel-tin alloys, nickel-phosphorus alloys (Ni-P series), nickel-iron-phosphorus alloys (Ni-Fe-P series). ), Nickel-cobalt-phosphorus alloys (Ni-Co-P-based).

  The metal film has a thickness of 0.01 mm to 0.5 mm, preferably 0.1 mm to 0.3 mm. If the thickness of the metal film is less than 0.01 mm, the transferability tends to improve, but since the durability of the metal film becomes poor, depending on the damage, deformation, and form of the metal film, There is a possibility of causing peeling of the metal film from the surface. On the other hand, when the thickness of the metal film exceeds 0.5 mm, cooling of the molten thermoplastic resin injected into the cavity is promoted, so that the transferability tends to be inferior. In addition, the thickness of a metal film means the height from the bottom face of a metal film to the convex part top surface of an uneven part, when the uneven part is formed in the metal film.

  In the present invention, a method for producing a metal film includes a method of producing a metal film by electroforming using a smooth glass surface as a mother mold. In this case, examples of the method of providing the uneven portion on the surface of the flat metal film include a method using a laser and a method of processing the surface of the metal film by machining or the like. In addition, as a method for manufacturing a metal film having a concavo-convex portion on the surface, a method of using a mother mold having a concavo-convex portion using a photoresist on a glass surface and manufacturing it by electroforming can be given. Further, examples of the method for providing the uneven portion on the surface of the flat metal film include a method using a laser and a method of processing the surface of the metal film by machining or the like. Alternatively, depending on the shape of the concavo-convex portion, the concavo-convex portion may be formed on the metal film by machining using a diamond tool, or the concavo-convex portion may be formed by a chemical method. In the latter case, a resist layer is applied to the surface of the metal film and, for example, a pattern is formed on the resist layer by irradiating the resist layer with ultraviolet rays through a desired mask, or the resist layer is formed by a printing method. Then, the metal film is etched using the resist layer as an etching mask, whereby an uneven portion can be formed in the metal film. If desired, the concavo-convex portion may be formed by performing formation and etching of the resist layer a plurality of times.

The cross-sectional shape when the concavo-convex portion provided on the surface of the metal film is cut along a vertical plane cannot be uniquely defined. A substantially spiral shape can be given as an arrangement state of the uneven portions. Here, the concavo-convex part includes a form in which a convex part exists on a plane and a form in which a concave part exists on a plane. The pitch of the uneven portions provided on the surface of the metal film is desirably 1 × 10 ⁻⁸ m to 1 × 10 ⁻⁵ m, preferably 5 × 10 ⁻⁸ m to 5 × 10 ⁻⁶ m. Further, the height (depth) of the concavo-convex part is desirably 1 × 10 ⁻⁹ m to 1 × 10 ⁻⁶ m, preferably 5 × 10 ⁻⁹ m to 5 × 10 ⁻⁷ m. It is not limited to.

  In the present invention, when the metal film is detachably disposed (placed) on the cavity surface of the nest, the metal film is prevented from moving due to the flow of the molten thermoplastic resin injected into the cavity during molding. It is good also as a structure fixed to the cavity surface of a nest | insert by vacuum suction in the peripheral part of a nest | insert. Specifically, a through hole is provided in the periphery of the nest, a metal film is disposed (placed) on the cavity surface of the nest so as to close the through hole, and the through hole is connected to a vacuum suction device. That's fine.

In the present invention, a hard thin film may be formed on the surface of the sprayed coating. As a result, it is possible to prevent the surface of the thermal spray coating from being damaged due to friction on the surface of the thermal spray coating caused by the expansion and contraction of the metal film due to the heat of the molten thermoplastic resin injected into the cavity. Furthermore, it is possible to prevent the surface of the sprayed coating from being damaged when the mold is handled. In this case, examples of the material constituting the thin film include materials selected from the group consisting of TiN, TiAlN, TiC, CBN, BN, amorphous diamond, CrN and Cr, and amorphous diamond or TiN and CrN are particularly preferable. . Moreover, the thin film should just be formed at least 1 layer, and may be a multilayer. For example, a thin film made of TiN may be formed on the surface of the thermal spray coating, and a thin film of amorphous diamond, CrN, or the like may be formed thereon. Alternatively, a SiO ₂ layer may be formed on the surface of the sprayed coating as a base layer, and a thin film such as amorphous diamond, TiN, or CrN may be formed thereon. As a method for forming a thin film on the surface of the sprayed coating, a chemical vapor deposition method (CVD method) such as atmospheric pressure CVD method, low pressure CVD method, thermal CVD method, plasma CVD method, photo CVD method, laser CVD method, vacuum deposition, or the like. Examples thereof include physical vapor deposition methods (PVD methods) such as a method, sputtering method, ion plating method, ion beam vapor deposition method, and IVD method (ion vapor deposition method).

The thickness of the thin film is 5 × 10 ⁻⁷ m to 2 × 10 ⁻⁵ m, preferably 1 × 10 ⁻⁶ m to 1.5 × 10 ⁻⁵ m, more preferably 2 × 10 ⁻⁶ m to 1. It is desirable to be 0 × 10 ⁻⁵ m. The surface roughness R _Z of the thin film surface is 1 nm to 19 nm, preferably 1 nm to 10 nm. Here, the surface roughness R _Z is based on the provisions of JIS B 0601: 2001. When the thickness of the thin film is less than 5 × 10 ⁻⁷ m, the strength of the thin film is reduced, and the thin film may be peeled off from the nest during molding. On the other hand, when the thickness of the thin film exceeds 2 × 10 ⁻⁵ m, the heat insulating property is lowered, the transferability starts to be lowered, and the cost required for forming the thin film is increased. Furthermore, by regulating the surface roughness of the thin film surface as described above, the adhesion of the metal film to the sprayed coating surface can be improved, and the metal film can be prevented from shifting from the nest during molding of the molded product. Transferability is also improved.

  A 1st metal mold | die part and a 2nd metal mold | die part can be produced from metal materials, such as carbon steel, stainless steel, an aluminum alloy, and a copper alloy. The structure of the molten resin injection part can be any known type of molten resin injection part (gate structure), for example, a direct gate structure, a side gate structure, a jump gate structure, a pinpoint gate structure, a tunnel gate. Examples include a structure, a ring gate structure, a fan gate structure, a disk gate structure, a flash gate structure, a tab gate structure, and a film gate structure. The molten resin injection part is provided in the first mold part, but may be provided in the first mold part and the second mold part depending on the structure. When the injection molding method (injection compression molding method) according to the second aspect of the present invention is adopted, the cavity volume may be made variable. In this case, for example, a movable core that can be moved by a hydraulic cylinder may be disposed in the mold assembly. Alternatively, the mold may have a structure in which a stamping structure is formed by the parting surface of the first mold part and the parting surface of the second mold part. Here, in the stamping structure, the parting surface of the first mold part and the parting surface of the second mold part are opposed to each other, and a cavity is formed even if the mold is not completely clamped. As described above, the first mold part and the second mold part are fitted to each other so that the parting surface of the first mold part and the parting surface of the second mold part slide with each other with a slight clearance. In the present invention, for example, the first mold part may be a fixed mold part and the second mold part may be a movable mold part.

  After processing into a predetermined shape by grinding, etc., when there is no risk of the metal block falling from the mounting part provided on the mold part and damaging when the insert is installed, or without using an adhesive When the block can be mounted on the mounting portion, the metal block can be directly mounted on the mounting portion provided on the mold portion without using an adhesive. Alternatively, the metal block may be bonded to the mounting portion using a thermosetting adhesive selected from epoxy, silicone, urethane, acrylic, etc., or the metal block may be attached with a bolt or the like. May be adhered to the mounting portion. The mounting core provided with the mounting portion may be attached to the mold portion, and the insert may be mounted on the mounting portion of the mounting core.

The molded product of the present invention for achieving the above object is a molded product molded by the injection molding method according to the first to second aspects of the present invention, including the various preferred configurations and forms described above. It is. Here, in the molded product of the present invention, the projected area of the portion facing the nesting is 500 cm ² or more, and the shape of the portion facing the nesting may have at least a plane or a curved surface. Furthermore, in the molded article of the present invention including such a form, it is possible to adopt a form in which holes are formed in a portion facing the insert.

  Specific examples of the molded article of the present invention include Fresnel lenses, personal computer housings, glazing, headlamps and taillights, spherical or aspherical lenses and mirrors, light guide plates, door handles, automobile center consoles, X Examples include a radiographic cassette case and a mobile phone housing.

  Examples of the thermoplastic resin suitable for use in the present invention include a crystalline thermoplastic resin and an amorphous thermoplastic resin. Specifically, polyolefin resins such as polyethylene resin and polypropylene resin; polyamide 6, Polyamide resins such as polyamide 66 and polyamide MXD6 (PA resins); Polyoxymethylene (polyacetal, POM) resins; Polyester resins such as polyethylene terephthalate (PET) resins and polybutylene terephthalate (PBT) resins; Polyphenylene sulfide resins; Styrenic resin such as polystyrene resin, ABS resin, AES resin, AS resin; methacrylic resin; polycarbonate resin (PC resin); modified polyphenylene ether (PPE) resin; polysulfone resin; It can be exemplified a liquid crystal polymer; over preparative resins; polyether imide resin; polyamideimide resin; polyimide resins; polyether ketone resins; polyether ether ketone resins; polyester carbonate resin.

  Furthermore, a thermoplastic resin made of a polymer alloy material can be used. Here, the polymer alloy material is composed of a blend of at least two types of thermoplastic resins, or a block copolymer or graft copolymer in which at least two types of thermoplastic resins are chemically bonded. A polymer alloy material is widely used as a high-functional material that can have the unique performance of each of the individual thermoplastic resins. As a thermoplastic resin constituting a polymer alloy material in which at least two kinds of thermoplastic resins are blended, styrene resins such as polystyrene resin, ABS resin, AES resin, and AS resin; polyolefin resins such as polyethylene resin and polypropylene resin; methacrylic resin Polycarbonate resin; polyamide resin such as polyamide 6, polyamide 66, polyamide MXD6; modified PPE resin; polyester resin such as polybutylene terephthalate resin and polyethylene terephthalate resin; polyoxymethylene resin; polysulfone resin; polyimide resin; Polyarylate resin; Polyether sulfone resin; Polyether ketone resin; Polyether ether ketone resin; Polyester carbonate resin Can. As a polymer alloy material obtained by blending two types of thermoplastic resins, a polymer alloy material of a polycarbonate resin and an ABS resin can be exemplified. Such a combination of resins is expressed as polycarbonate resin / ABS resin. The same applies to the following. Furthermore, as a polymer alloy material blended with at least two types of thermoplastic resins, polycarbonate resin / PET resin, polycarbonate resin / PBT resin, polycarbonate resin / polyamide resin, polycarbonate resin / PBT resin / PET resin, modified PPE resin / HIPS Examples thereof include resin, modified PPE resin / polyamide resin, modified PPE resin / PBT resin / PET resin, modified PPE resin / polyamide MXD6 resin, polyoxymethylene resin / polyurethane resin, and PBT resin / PET resin.

  In addition, an additive, a filler, and a reinforcing agent can also be added to the various thermoplastic resins described above.

  As additives, plasticizers; stabilizers; antioxidants: UV absorbers; UV stabilizers such as nickel-bis (octylphenyl) sulfide and other organic nickel compounds, hindered amine compounds; antistatic agents; flame retardants; Mold inhibitors such as liquid paraffin, polyethylene wax and fatty acid amide; Organic foaming agents such as ADCA; Transparent nucleating agents; Various colorants such as organic pigments, inorganic pigments and organic dyes; An impact-strengthening agent such as acrylic graft polymer and MBS.

  Plasticizers such as diethyl phthalate, di-n-butyl phthalate, 2-ethylhexyl phthalate, diisononyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate; triethyl phosphate, tributyl phosphate, phosphoric acid Phosphate esters such as tricresyl, triphenyl phosphate; fatty acid base esters such as butyl oleate, dibutyl adipate, adipic acid-n-hexyne, di-2-ethylhexyl adipate; alcohol esters such as diethylene glycol dibenzoate Oxyacid esters such as acetyltriethyl citrate and dibutyl maleate; trimellitic plasticizer; polyester plasticizer; epoxy system; chlorinated paraffinic plasticizer.

  As stabilizers, organotin stabilizers such as di-n-octyltin compounds, di-n-butyltin compounds, and dimethyltin compounds; lead compound systems such as tribasic lead sulfate, dibasic lead phosphite, and lead silicate Stabilizers; metal soap-based stabilizers such as cadmium soap, lead soap, zinc soap; trisnonyl phosphate; trisnonylphenyl phosphate;

  As antioxidants, phenolic antioxidants such as dibutylcresol and butylhydroxyanisole; bisphenolic antioxidants such as methylenebis (methylbutylphenol) and thiobis (methylbutylphenol); tris (methylhydroxybutylphenyl) butane, tocophenol, etc. And polyphosphoric antioxidants; organic sulfur compounds such as dimyristylthiodipropionate; and organic phosphorus compounds such as tris (mono / dinonylphenyl) phosphite.

  As UV absorbers, salicylic acid UV absorbers such as phenyl salicylate and butylphenyl salicylate; benzophenone UV absorbers such as dihydroxybenzophenone; benzotriazole UV absorbers such as (hydroxymethylphenyl) benzotriazole; ethylhexylcyanodiacrylate Examples include cyanoacrylate-based ultraviolet absorbers such as phenonyl.

  Antistatic agents such as poly (oxyethylene) alkylamines, poly (oxyethylene) alkylphenyl ethers, and other nonionic surfactant antistatic agents; alkylsulfonates, alkylbenzenesulfonates, alkylphosphates, etc. Examples include ionic surfactant-based antistatic agents; cationic surfactant-based antistatic agents such as quaternary ammonium chloride; amphoteric surfactants; and conductive resins.

  As flame retardants, halogen flame retardants such as tetrabromobisphenol A, polybromobiphenol, bis (hydroxydibromophenyl) propane, chlorinated paraffin; phosphorus flame retardants such as ammonium phosphate and tricresyl phosphate; antimony trioxide; red phosphorus ; Tin oxide etc. can be mentioned.

  As fillers and reinforcing agents, inorganic materials: stainless steel fibers, high-strength amorphous metal fibers, stainless steel foils, steel foils, copper foils and other metal materials; high-molecular polyethylene fibers, high-strength polyarate fibers, para-type all Organic materials such as aromatic polyamide fiber, aramid fiber, PEEK fiber, PEI fiber, PPS fiber, fluororesin fiber, phenol resin fiber, vinylon fiber, and polyacetal fiber;

  As inorganic fillers and reinforcing agents, glass materials such as glass fibers, long glass fibers, and quartz glass fibers; carbon materials such as PAN carbon fibers, pitch carbon fibers, and graphite whiskers; silicon carbide fibers, silicon carbide Silicon carbide materials such as continuous fibers, silicon carbide whiskers, silicon carbide whisker sheets; boron materials such as boron fibers; Si—Ti—C—O materials such as Si—Ti—C—O fibers; potassium titanate fibers, titanium Examples thereof include potassium titanate materials such as potassium acid whisker and potassium titanate conductive whisker; silicon nitride materials such as silicon nitride whisker and silicon nitride whisker sheet; and calcium sulfate materials such as calcium sulfate whisker.

  As powder filler and reinforcing agent, mica flake, mica powder, shirasu balloon, silica fine powder, talc powder, aluminum hydroxide powder, magnesium hydroxide powder, magnesium silicate powder, calcium sulfate fine powder, spherical hollow glass powder, metallization Powder, high purity synthetic silica fine powder, tungsten disulfide powder, tungsten carbide powder, zirconia fine powder, zirconia fine powder, partially stabilized zirconia powder, alumina-zirconia composite powder, composite metal powder, iron powder, aluminum powder, molybdenum metal Examples thereof include powder, tungsten powder, aluminum nitride powder, nylon fine particle powder, silicone resin fine powder, spinel powder, amorphous alloy powder, aluminum flake, and glass flake.

  In the present invention, the thermal spray coating as the heat insulating coating is formed by the thermal spraying method. Therefore, various problems when the insert is made from a dense but brittle material such as a sintered body (a firing furnace problem, a crack problem during manufacturing, a problem of breakage during use, and a very high manufacturing cost. No problem occurs, and the nesting is not subject to various restrictions due to, for example, the structure of the mold, the shape of the cavity, or the molded product. Moreover, the thermal spray coating which has heat insulation property and is not easily damaged has a porosity changed in the thickness direction, and the porosity is lower as the side is closer to the surface of the thermal spray coating. That is, the surface of the sprayed coating is dense. Therefore, there are few unevenness | corrugations in the sprayed coating surface, and the sprayed coating surface is excellent in smoothness. Therefore, the surface state of the thermal spray coating is reflected in the surface state of the metal film disposed on the surface of the thermal spray coating, but the surface of the metal film is also excellent in smoothness, and many irregularities are transferred to the surface of the molded product, There is no problem that a high-quality molded product cannot be obtained, and there is no problem with the durability of the sprayed coating.

  Moreover, since a metal film is disposed on the surface of the insert (specifically, on the thermal spray coating), it is possible to impart a higher mirror surface to the surface of the molded product. High optical properties can be imparted. Further, by processing the surface of the metal film into a desired shape, the shape processed on the surface of the metal film can be transferred to the surface of the molded product with high accuracy.

  Further, since the surface of the sprayed coating is dense, when a metal film is formed by plating, pinholes are hardly generated in the metal film, and the thickness of the metal film can be reduced. Alternatively, since the surface of the thermal spray coating is dense, even when a stamper structure is adopted, the thermal spray particles do not fall off the nesting surface during molding, and the back surface of the metal film is worn during molding. Thus, it is possible to surely prevent the occurrence of problems such as the metal powder of the metal film being mixed in the molded product or the fine undulation occurring on the surface side of the metal film. In addition, when changing the pattern of the concavo-convex portion depending on the molded product, it is not necessary to make a nesting each time, only the metal film needs to be produced and the metal film only needs to be replaced, which increases the manufacturing cost of the molded product. Therefore, it is possible to reduce the molding cost of the molded product and shorten the time [TAT (Turn Around Time)] required from the design of the molded product to the molding of the molded product as an actual product.

  When the porosity of the sprayed coating is very small, the roughness of the surface of the sprayed coating after lapping is reduced, but the thermal conductivity is increased. Further, such a sprayed coating is liable to generate cracks during production, and it is difficult to increase the film thickness. Therefore, by changing the porosity in the thickness direction of the thermal spray coating, making the vicinity of the surface dense and roughening the vicinity of the metal block, the thermal conductivity of the entire thermal spray coating is low, and after the lapping finish A sprayed coating having a small surface roughness can be obtained. In addition, since a thermal spray coating having a low thermal conductivity and a large thickness can be obtained, for example, in the injection molding process, the molten thermoplastic resin is rapidly cooled, so that the molded product has poor appearance and poor transfer. It is possible to reliably prevent the occurrence. Furthermore, there is no generation of weld lines or flow marks, no warping or sinking, excellent transferability, very high gloss, and a molded product with very little distortion inside. Further, even when a hole is formed in a molded product, it is possible to reliably prevent the occurrence of a weld line as will be described later.

Therefore, the surface is the same without using a conventional mold assembly that employs a complicated mold assembly as a countermeasure for preventing damage to the insert, using a insert made of a ceramic sintered body that is all dense. It is possible to provide a mold assembly that forms a molded product having quality, that is, excellent appearance characteristics. In addition, the size of the nest is basically not limited as long as it can be sprayed by the thermal spraying apparatus. For example, a large nest exceeding 500 cm ² can be provided relatively easily and inexpensively. Is possible.

  Further, in the obtained molded product, even when it is molded using a thermoplastic resin blended with a filler such as glass fiber, in order to prevent quenching of the molten thermoplastic resin in the cavity, Since the floating of the filler can be prevented and the rapid development of the solidified layer in the molten thermoplastic resin injected into the cavity can be suppressed, the fluidity of the molten thermoplastic resin in the cavity Compared to the case of nesting made of steel, there is also an effect that is increased by about 30 to 30%, and in particular, a large molded product or a thin molded product can be easily molded. Moreover, since it can be applied to a molded product having a three-dimensional curvature, the application range can be greatly expanded.

  When providing a hole in a molded product, a metal first core member is disposed in the first mold part, and a metal second core member is disposed in the second mold part. Then, the cavity is formed by clamping the first mold part and the second mold part. In addition, in the state which clamped the 1st metal mold | die part and the 2nd metal mold | die part, the front-end | tip surface of a 1st core member and the front-end | tip surface of a 2nd core member will be in the state which contacted, or the state which faced. Then, the molten thermoplastic resin is injected into the cavity, but the molten thermoplastic resin flows around the core member, and the thermoplastic resin whose surface layer has cooled down merges. As a result, a streak called a weld line is formed at the merged portion. The line often occurs. As a method for solving such a phenomenon, an annular sintered body (referred to as an annular sintered body) is produced, and the annular sintered body is inserted into the core member and bonded to the core member with an adhesive or the like. be able to. However, in such a method, the weld line can be eliminated, but it is necessary to produce an annular sintered body as a separate part from the insert that constitutes the cavity surface. There is a high risk of breakage when the first mold part and the second mold part are clamped. In particular, when the cavity has a complicated three-dimensional shape or part of a sphere, it cannot be accurately processed or bonded to the first mold part or the second mold part where the annular sintered body is to be fixed. Probability is high. Furthermore, a slight clearance is required between the annular sintered body and the insert to prevent breakage, and it becomes difficult to produce the annular sintered body and the insert.

  In the present invention, since the thermal spray coating is formed on the surface of the nesting by the thermal spraying process, the nesting can be easily performed even when the nesting constitutes a part of the cavity surface composed of a complicated three-dimensional shape or a spherical surface. Can be produced. In addition, the generation of weld lines can be reliably prevented. Further, when a protrusion (corresponding to a core member) is provided in the insert in order to provide a hole in the molded product, a metal base layer having a thickness of 0.03 mm to 1 mm is formed on the surface of the protrusion, A thermal spray coating made of ceramics may be formed on the formation. However, it is not necessary to form a metal underlayer and a sprayed coating on the contact surface or the opposing surface of the protrusion. In this case, a metal film may or may not be disposed on the thermal spray coating provided on the protrusion. Even in the above case, the thermal spray coating has a porosity that changes in the thickness direction, and the porosity needs to satisfy the requirement that the closer to the surface of the thermal spray coating, the lower the value. When the requirements are not satisfied, there is a possibility that the thermal spray coating itself is damaged by the thermoplastic resin that has entered the gap when the first mold part and the second mold part are released.

  Hereinafter, the present invention will be described based on examples with reference to the drawings.

  Example 1 relates to the mold assembly of the present invention, the injection molding method according to the first aspect of the present invention, and the molded article of the present invention.

The molded product of Example 1 is a molded product molded by the injection molding method of Example 1, has a projected area of 500 cm ² or more, and has at least a flat shape. More specifically, in Example 1, the molded product was a housing for a personal computer. Here, the personal computer housing specifically includes a cover that surrounds the portion of the liquid crystal display device, a main cover that corresponds to the back surface thereof, and a cover that is installed to surround the key top and the back surface thereof. It consists of a cover. Such personal computer housings are molded using PC resin / ABS resin or PC resin, and notebook personal computers are often used especially for carrying. Such measures are taken.

  Since the housing itself has become very thin due to the influence, it has become difficult to completely fill the cavity, particularly with the molten thermoplastic resin, in the cavity. Therefore, if a multi-point gate structure is used to shorten the flow distance of the molten thermoplastic resin in the cavity in order to completely fill the cavity with the molten thermoplastic resin, a weld line is generated and the filling pressure ( When the injection pressure is increased, problems such as large warpage of the obtained housing and appearance defects such as flow marks occur. Also, in terms of materials, we have taken measures to reduce the molecular weight or use a fluidity improver, etc., for the purpose of improving fluidity, but there is a problem of causing damage at the time of dropping due to a decrease in the strength of the housing. is there.

  Further, painting the housing to improve the appearance of the molded product may have a poor coating yield, and the number of non-painted type housings is increasing for the purpose of cost reduction. In other words, the housing is finely textured, or the outer surface of the housing is a mirror surface. By the way, in molding the housing, it is necessary to increase the transferability because the glossiness or high gloss does not appear unless the transferability of the texture or mirror surface is increased. For this reason, when the mold temperature is increased, there arises a problem that the molding cycle becomes longer as a result. Moreover, in the high gloss product, the warp of the housing is easily noticeable.

  In Example 1, the main cover on the back surface of the liquid crystal display device was molded as the housing of a nominal 12-inch notebook personal computer. This main cover has a flat shape of 200 mm × 270 mm, the thickness of the flat portion is 1.5 mm, and a box-shaped (concave) molded product in which a side wall having a height of 3 mm is provided on the outer edge of the flat portion. It is.

As shown in FIG. 2, the mold assembly 10 of the first embodiment has a conceptual diagram.
(A) a first mold part (fixed mold part) 11, a second mold part (movable mold part) 12, and a molten resin injection part 14 provided in the first mold part 11, A mold in which a cavity 13 is formed by clamping the first mold part 11 and the second mold part 12;
(B) Nests 20 </ b> A and 20 </ b> B that are arranged in the first mold part 11 and the second mold part 12 and form a surface constituting the cavity 13, and
(C) Metal films 40A and 40B having a thickness of 0.03 mm to 0.5 mm disposed on the surface of the insert, forming a surface constituting the cavity 13;
It has. The molten resin injection part 14 has a side gate structure with one gate.

Then, as shown in a schematic cross-sectional view in FIG. 1A and an enlarged schematic partial cross-sectional view in FIG.
(A) Metal blocks 31A, 31B,
(B) metal underlayers 32A and 32B having a thickness of 0.03 mm to 1 mm formed on at least the surfaces of the metal blocks 31A and 31B facing the cavity 13 (the top surfaces of the metal blocks 31A and 31B), and
(C) Thermal spray coatings 33A and 33B made of ceramics formed on the metal base layers 32A and 32B,
It is composed of The inserts 20A and 20B are fixed to the first mold part (fixed mold part) 11 and the second mold part (movable mold part) 12 using bolts (not shown).

  Here, the thermal spray coatings 33A and 33B have the porosity changed in the thickness direction, and the porosity is closer to the surface of the thermal spray coatings 33A and 33B (the portion closer to the surface of the thermal spray coatings 33A and 33B). ), Low value. In FIG. 1B or FIG. 1C described later, the pores are illustrated as being aligned, but in reality, the pores are randomly formed. Moreover, although the closed pore (closed hole) is illustrated exclusively, of course, an open pore (open hole) also exists. Depending on the drawings, the metal blocks 31A and 31B and the thermal spray coatings 33A and 33B may be collectively represented by reference numerals 34A and 34B.

Specifically, the metal blocks 31A and 31B are made of SUS420J2 (HPM38 manufactured by Hitachi Metals, Ltd.) having a linear expansion coefficient of 11.5 × 10 ⁻⁶ / ° C. at 20 ° C. to 200 ° C. Yes. Further, the metal base layers 32A and 32B having a thickness of 0.08 mm are required to firmly adhere the thermal spray coatings 33A and 33B to the metal blocks 31A and 31B, and the composition thereof is Ni—Cr (more specifically, Ni-20% Cr) and is formed on the top surfaces of the metal blocks 31A and 31B based on the thermal spraying method.

Here, in the inserts 20A and 20B for forming the main cover, the shape of the insert 20A arranged in the first mold part 11 is a “concave” shape, and the external dimensions (vertical × horizontal × thickness). ) Is 210 mm × 280 mm × 30 mm, and the dimensions (recesses) of the nest 20A for molding the outer surface of the main cover are 202 mm × 272.7 mm × 3 mm in length × width × depth, and face the nest 20A. The projected area of the part of the molded product is about 551 cm ² . On the other hand, the shape of the insert 20B arranged in the second mold part 12 is “convex”, and the outer dimensions (vertical × horizontal × thickness) are 210 mm × 280 mm × 30 mm, and the inner surface of the main cover is molded. The dimension (width × width × height) of the portion (convex portion) of the insert 20B is 198 mm × 268.7 mm × 1.5 mm, and the projected area of the portion of the molded product facing the insert 20B is about 532 cm ² . Further, in the boundary region (corner portion) between the flat portion and the side wall, a curvature having a diameter of 1.0 mm is given to the outer surface side of the main cover, and a curvature having a diameter of 0.8 mm is given to the inner surface side of the main cover. It is attached. Here, the thermal spray coatings 33A and 33B are formed on the metal blocks 31A and 31B facing the outer and inner surfaces of the main cover.

In Example 1, the thermal spray coatings 33A and 33B are composed of two unit layers having different compositions, and are formed by a plasma spraying apparatus. Specifically, the first layer (lower layer) 33 ′ constituting the sprayed coatings 33A and 33B is made of ZrO ₂ , and the second layer (upper layer) 33 ″ is made of Al ₂ O ₃ . , 33B has a mirror finish. Here, metal films 40A, 40B are disposed on the surface of the second layer (upper layer) 33 ″. Specifically, after etching the surface of the second layer (upper layer) 33 ″ with an acid, metal films 40A and 40B made of Ni—P and having a thickness of 100 μm are formed on the second layer by electroless plating. It is formed on the surface of the eye (upper layer) 33 "and then mirror-finished. Thus, the metal films 40A and 40B having _a surface roughness _Ra of 0.005 μm and a mirror finished thickness of 80 μm can be obtained.

  Table 1 shows the composition and thickness of the metal underlayer in Example 1 or in Examples 2 to 4 described later; the composition, layer configuration, total thickness, and thermal conductivity of the thermal spray coatings 33A and 33B; Composition, thickness, porosity average value, average particle diameter, surface roughness of second layer (upper layer) unit layer 33 ″ or thermal spray coatings 33A, 33B constituting coatings 33A, 33B; thermal spray coatings 33A, 33B Composition, thickness, porosity average value, average particle size of the first layer (lower layer) unit layer 33 ′ constituting; average porosity of surface region, average particle size; average porosity value, average of bottom region The particle size is shown.

  The injection molding conditions in Example 1 are illustrated in Table 2 below. In the first embodiment, as shown in FIG. 2 which is a conceptual diagram of the mold assembly 10A, a first mold part (fixed mold part) 11, a second mold part (movable mold part) 12, and And the cavity 13 is formed. Then, after plasticizing, melting, and weighing the thermoplastic resin shown in Table 2 in the injection cylinder 16, from the injection cylinder 16 through the runner part and the sprue part 15 and the molten resin injection part (gate part) 14, Under the injection conditions shown in Table 2, the molten thermoplastic resin was injected into the cavity 13 and a part of the cavity 13 was filled with the molten thermoplastic resin. Next, the thermoplastic resin in the cavity 13 was cooled and solidified, and then the obtained molded product was released from the mold.

[Table 2]
Injection molding machine: Nissei Plastic Industry Co., Ltd. AZ7000
Thermoplastic resin: PC / ABS resin (MB8300 manufactured by Mitsubishi Engineering Plastics Co., Ltd.)
Resin temperature: 260 ° C
Mold temperature: 70 ° C
Injection pressure: 90 MPa

  Although it was the molten resin injection portion 14 having a side gate structure with one gate point, the transferability was very good, and the main cover had very high gloss. In addition, the main cover was not warped, so it was very luxurious. Further, although molding was performed 50,000 times, no damage or the like occurred in the inserts 20A and 20B.

  For comparison, when injection molding was performed using an insert made of steel, the cavity 13 could not be completely filled with the molten thermoplastic resin. Therefore, when the injection temperature was changed by changing the resin temperature to 280 ° C. and the mold temperature to 80 ° C., the molten thermoplastic resin could be completely filled in the cavity 13, but the molded product was Weld lines were generated, and gaseous white marks and silver were generated around the weld lines and in the vicinity of the molten resin injection part 14, and the appearance of the molded product was very faint. Moreover, since the resin is forcibly filled into the cavity 13, the molded product is warped.

  For comparison, in Table 3, the composition and thickness of the metal underlayer in Comparative Example 1A, Comparative Example 1B, and Comparative Example 1C; Composition of the entire sprayed coating, layer configuration, total thickness, thermal conductivity; Composition, thickness, porosity average value, average particle size, surface roughness of the second layer (upper layer) unit layer or thermal spray coating; composition of the first layer (lower layer) unit layer constituting the thermal spray coating, Thickness, average porosity, average particle size; average porosity of surface region, average particle size; average porosity, average particle size of bottom region.

  Here, in Comparative Example 1A, Comparative Example 1B, and Comparative Example 1C, the metal underlayer is not formed. In Comparative Example 1A, the thermal spray coating is composed of two unit layers having the same composition. In Comparative Example 1B, the thermal spray coating is composed of two unit layers having different compositions. In Comparative Example 1C, the thermal spray coating is composed of a single-layer thermal spray coating. In Comparative Example 1C, the thermal spray coating was formed so that the porosity value of the entire one thermal spray coating was the same.

  When the surface of the thermal spray coating obtained by Example 1 or Example 2 to Example 4 described later was visually observed, it had high gloss, the surface was smooth, and cracks were observed. There wasn't. On the other hand, in Comparative Example 1A, the surface of the sprayed coating was rough and the surface roughness was very rough. Moreover, when the surface of the thermal spray coating obtained by Comparative Example 1B was visually observed, cracks were generated. Furthermore, when the surface of the thermal spray coating obtained by Comparative Example 1C was visually observed, large irregularities were observed on the surface. In addition, the sample obtained in the comparative example was also peeled off at the interface with the metal block.

  Example 2 is a modification of Example 1 and relates to the injection molding method according to the first aspect of the present invention, and adopted a gas assist molding method for molding a molded product having a hollow portion.

  In Example 2, the molded product was an automobile outer door handle, more specifically, a bar-type outer door handle. A door handle for an automobile is usually made of a polycarbonate (PC) alloy or a polyamide (PA) resin from a non-filler thermoplastic resin. However, in some cases, a thermoplastic resin to which a filler is added is used. There is also. And although it may be used without painting, it is often used in a state where added value is increased by painting or plating. However, there are many defects such as filler floating on the door handle surface, coating failure, plating adhesion failure, etc., and it cannot be said that the yield is high. One of the causes is poor appearance quality (transfer defect, filler floating, etc.) due to the solidified layer generated when filling the cavity of the molten thermoplastic resin. In addition, when plating is performed on the surface of a door handle that is molded using a thermoplastic resin to which rubber particles are added, the result is that the added rubber particles are broken or stretched due to the shear stress generated on the surface layer of the door handle. Even if etching is performed during plating, small rubber particles are not etched, and poor plating adhesion often occurs. Recently, taking into account the plating yield, it is also considered to form a metal layer on the door handle surface by physical vapor deposition (PVD) including vapor deposition and ion plating. The appearance quality of the handle surface is directly related to the yield.

  The pull-up type door handle can be manufactured by cutting and polishing a sintered body (nesting) for forming the portion in order to improve the appearance quality of only the portion corresponding to the appearance portion of the molded product. . However, since the bar-type outer door handle has a three-dimensional shape and has a shape with a keyhole portion, it is very difficult to cut the sintered body.

  In Example 2, as a bar-type outer door handle for an automobile, a door handle having a three-dimensional shape of 150 mm × 30 mm and a height of 20 mm and having a keyhole portion was formed.

In the nesting in the second embodiment, specifically, the metal blocks 31A and 31B are made of SUS420J2 (HPM38 manufactured by Hitachi Metals, Ltd.) as in the first embodiment. Moreover, the composition of the metal base layers 32A and 32B having a thickness of 0.08 mm is Ni—Cr (more specifically, Ni-20% Cr), as in Example 1, and is made of metal based on the thermal spraying method. It is formed on the top surfaces of the blocks 31A and 31B. The surfaces of the metal blocks 31A and 31B facing the cavity 13 have a cubic curved surface shape for molding the outer door handle. Further, the sprayed coatings 33A and 33B are provided on the entire surface except for the metal blocks 31A and 31B corresponding to the attachment surface to the vehicle body. Here, also in Example 2, the thermal spray coatings 33A and 33B are composed of two unit layers having different compositions, and are formed by a plasma spraying apparatus. Specifically, the first layer (lower layer) 33 ′ constituting the sprayed coatings 33A and 33B is made of Al ₂ O ₃ , and the second layer (upper layer) 33 ″ is made of ZrO ₂ . 33B has a mirror finish. Further, metal films 40A and 40B are disposed on the surface of the second layer (upper layer) 33 ″. Specifically, after etching the surface of the second layer (upper layer) 33 ″ with an acid, an Ni—P layer having a thickness of 80 μm is formed by an electroless plating method to obtain the metal films 40A and 40B. In this way, the metal films 40A and 40B having _a surface roughness _Ra of 0.008 μm and a thickness of 70 μm after the mirror finish can be obtained.

  The part of the mold corresponding to the through hole part of the key hole part has a push-cut core structure. More specifically, a protrusion (corresponding to a core member) is provided on the surface of the metal blocks 31A and 31B facing the cavity 13, and the above-described metal underlayer is formed on the surface of the protrusion, thereby forming a metal underlayer. A thermal spray coating made of ceramic is formed on the top. However, when the mold is clamped, it is not necessary to form a metal base layer and a sprayed coating on the opposing surfaces of the protruding portions where the protruding portions face each other with a gap of 3 μm.

  Furthermore, since the thickness of the outer door handle is as thick as 20 mm, there is a risk of sinking in general injection molding, and a gas assist molding method using nitrogen gas as a pressurized fluid was adopted. Therefore, the pressurized fluid introduction pipe and the pressurized fluid injection nozzle 17 are installed in the second mold part (movable mold part). A moving means 18 comprising a hydraulic cylinder is attached to the rear part of the pressurized fluid injection nozzle 17.

  The injection molding conditions in Example 2 are illustrated in Table 4 below. Also in the second embodiment, as shown in FIG. 3 which is a conceptual diagram of the mold assembly 10B, a first mold part (fixed mold part) 11, a second mold part (movable mold part) 12, and And the cavity 13 is formed. The mold is provided with an overflow cavity 19 communicated with the cavity 13 so that a part of the molten thermoplastic resin injected into the cavity 13 can flow into the mold. Then, the pressurized fluid injection nozzle 17 was moved in the direction toward the cavity 13 by the operation of the moving means 18 and positioned at the forward end (see FIG. 3). In this state, the pressurized fluid injection nozzle 17 communicates with the cavity 13. And after plasticizing, melting and weighing the thermoplastic resin shown in Table 4 in the injection cylinder 16, from the injection cylinder 16 through the runner part and the sprue part 15, the molten resin injection part (gate part) 14, Under the injection conditions shown in Table 4, the molten thermoplastic resin was injected into the cavity 13 and a part of the cavity 13 was filled with the molten thermoplastic resin. In Example 2, a molten thermoplastic resin having a capacity satisfying about 50% of the cavity volume was injected into the cavity 13. Thereafter, 150 MPa of nitrogen gas was injected into the molten thermoplastic resin in the cavity 13 from the pressurized fluid injection nozzle 17. A part of the molten thermoplastic resin injected into the cavity 13 flows into the overflow cavity 19. Next, the thermoplastic resin in the cavity 13 was cooled and solidified, and then the obtained molded product was released from the mold.

[Table 4]
Injection molding machine: Nissei Plastic Industry Co., Ltd. AZ7000
Thermoplastic resin: PC / PBT resin (Mitsubishi Engineering Plastics MB4303)
Resin temperature: 270 ° C
Mold temperature: 80 ° C
Injection pressure: 80 MPa

  Since the gas assist molding method was adopted, no occurrence of sink marks was observed in the outer door handle, and the transferability was excellent, so that the gloss was very high. In addition, there was no occurrence of a weld line generated by the joining of the solidified thermoplastic resins around the keyhole portion, and the occurrence of the “color unevenness” phenomenon, which is a phenomenon peculiar to gas assist molding. The “color unevenness” is color unevenness generated as a result of the injected pressurized fluid being mixed with the molten thermoplastic resin near the cavity surface. Moreover, when an aluminum thin film having a thickness of 0.1 μm was formed on the surface of the outer door handle by vapor deposition, an outer door handle having an extremely excellent metallic luster and excellent in specularity on all surfaces was completed. Further, although molding was performed 50,000 times, no damage or the like occurred in the inserts 20A and 20B.

  For comparison, when injection molding was performed using a insert made of steel, the molten thermoplastic resin could not be completely filled into the cavity 13, and nitrogen gas was injected into the molten thermoplastic resin in the cavity 13. As a result, the obtained molded product had holes as defective portions. Therefore, when the injection pressure was changed to 120 MPa and gas assist molding was performed, the cavity 13 could be completely filled with the molten thermoplastic resin, and a hole as a defective portion was opened in the obtained molded product. Although there was no, a molding defect that occurs when the filling speed is slow, such as during thick wall molding, called `` Yujiwa '', occurs on the surface near the portion corresponding to the molten resin injection part of the outer door handle. The outer door is less glossy than that of the second embodiment, has a weld line around the keyhole portion, and has a “color unevenness” phenomenon, which is excellent in appearance. I couldn't get a handle. Further, when an aluminum thin film having a thickness of 0.1 μm was formed on the surface of the outer door handle by a vapor deposition process, a defective molding portion was extremely noticeable.

  The third embodiment is also a modification of the first embodiment.

  Liquid crystal display devices used in personal computers, mobile phones, PDAs, etc., have surface light source devices to meet the demands for thin, light weight, power saving, high brightness and high definition of liquid crystal display devices. It has been incorporated. The planar light source device is generally provided with a wedge-shaped light guide plate having a tapered inclined surface. The light guide plate has a flat first surface and a flat second surface facing the first surface, and is generally made of a transparent material.

  Also, lamps and lights in transportation means such as automobiles, trains, ships, airplanes (for example, headlights, taillights, high-mount stoplights, small lights, turn signal lamps, fog lights, indoor lights, meter panel lights, various types Built-in light source, destination indicator, emergency light, emergency exit light, etc.), various lights and lights in buildings (outdoor light, interior light, lighting equipment, emergency light, emergency exit light, etc.), street light, The light guide plate can also be used for various indicator lamps in traffic lights, signboards, machines, devices, etc., and in lighting fixtures and lighting units in tunnels and underground passages.

  If such a light guide plate is incorporated in a liquid crystal display device, a liquid crystal display device with extremely bright display can be obtained, and power consumption can be reduced. For example, if a light guide plate is applied to a lamp typified by a lamp in a transportation means, a uniform luminance distribution and high luminance can be achieved without providing irregularities on a light transmitting member such as a lamp that emits light. At the same time, since the reflecting member (reflector) can be made flat, the volume of the lamp can be reduced, and as a result, the installation place of the lamp is reduced. If the light source is a fluorescent tube or a light emitting diode, power saving and energy saving can be achieved, and light from the light source can be effectively used. Furthermore, the light from a light source (for example, a fluorescent lamp) should be used effectively and efficiently, for example, in a lamp typified by an indoor lamp, or in a room, basement, or underground passage that is not illuminated by sunlight. It is possible to achieve energy saving, which makes it possible to reduce the number of light sources. Further, if natural light is used as a light source, further energy saving can be achieved.

  In Example 3, such a light guide plate was used as the molded product. More specifically, the light guide plate of Example 3 is a wedge-shaped light guide plate having a size of 270 mm × 190 mm and a thickness changing from 2.5 mm to 1.0 mm.

In the nesting in the third embodiment, specifically, the metal blocks 31A and 31B are made of SUS420J2 (HPM38 manufactured by Hitachi Metals, Ltd.) as in the first embodiment. In addition, the thickness of the metal block 31A changes sequentially. On the other hand, the thickness of the metal block 31B is constant. A thermal spray coating is formed on the surface corresponding to the cavity surface of the metal blocks 31A and 31B. The composition of the metal base layers 32A and 32B having a thickness of 0.05 mm is Ni—Cr (more specifically, Ni-20% Cr), as in Example 1, and is made of metal based on the thermal spraying method. It is formed on the top surfaces of the blocks 31A and 31B. Thermal spray coatings 33A and 33B are formed on the metal base layers 32A and 32B. In Example 3, the thermal spray coatings 33A and 33B are enlarged schematic views of the nestings 20A and 20B in FIG. As shown in a partial sectional view, it is composed of one unit layer (made of ZrO ₂ ) and is formed by a plasma spraying apparatus. Further, the surfaces of the sprayed coatings 33A and 33B have a mirror finish.

  In the third embodiment, unlike the first embodiment, the metal films 40A and 40B are made of a nickel (Ni) thin film having a thickness of 0.3 mm, and the inserts 20A and 20B (specifically, the thermal spray coatings 33A and 33B). ) Is detachably disposed (mounted) by an appropriate method. That is, the third embodiment has a so-called stamper structure. Prism-shaped uneven portions are formed on the cavity surfaces of the metal films 40A and 40B placed on the inserts 20A and 20B. That is, the concavo-convex portion has a pitch of 50 μm, and the shape of the concavo-convex portion when the concavo-convex portion is cut by a virtual plane perpendicular to the extending direction of the concavo-convex portion is an isosceles triangle. In addition, the extending direction of the uneven portion in the metal film 40A placed on the insert 20A is orthogonal to the extending direction of the uneven portion in the metal film 40B placed on the insert 20B. The surfaces of the metal films 40A and 40B facing the thermal spray coatings 33A and 33B are flat. The metal films 40 </ b> A and 40 </ b> B can be manufactured by electroforming using, for example, a mother type in which a concavo-convex portion is provided using a photoresist on a glass surface.

  The injection molding conditions in Example 3 are illustrated in Table 5 below. Even in the third embodiment, as shown in FIG. 2 which is a conceptual diagram of the mold assembly 10A, a first mold part (fixed mold part) 11, a second mold part (movable mold part) 12, and And the cavity 13 is formed. Then, after plasticizing, melting, and weighing the thermoplastic resin shown in Table 5 in the injection cylinder 16, from the injection cylinder 16 through the runner part and the sprue part 15 and the molten resin injection part (gate part) 14, Under the injection conditions shown in Table 5, the molten thermoplastic resin was injected into the cavity 13 and a part of the cavity 13 was filled with the molten thermoplastic resin. Next, the thermoplastic resin in the cavity 13 was cooled and solidified, and then the obtained molded product was released from the mold.

[Table 5]
Injection molding machine: Sumitomo Heavy Industries, Ltd. SE-150D
Thermoplastic resin: PC resin (HL7001 manufactured by Mitsubishi Engineering Plastics)
Resin temperature: 300 ° C
Mold temperature: 100 ° C
Injection pressure: 150 MPa

  Although it was the molten resin injection part 14 having a side gate structure with one gate point, the transferability is very excellent, and it is provided on the surface of the metal film 40A, 40B on the surface of the molded product (light guide plate). The irregularities were transferred very accurately. Specifically, when the transfer rate was measured with a laser microscope (OLS1100 manufactured by Olympus Corporation), both surfaces of the light guide plate showed a transfer rate of 95 to 97%, indicating a very high transfer rate. Further, although molding was performed 50,000 times, no damage or the like occurred in the inserts 20A and 20B.

  Example 4 is also a modification of Example 1, but in Example 4, the injection molding method according to the second aspect of the present invention was employed. The mold has a stamping structure capable of injection compression molding.

  In Example 4, the molded product was glazed. The glazing is a window glass for a vehicle, and means a window glass at the foot of a rear pillar glass or a sunroof, a sunroof, a train, a truck or the like that does not interfere with driving. Glazing has traditionally been made of glass, but in recent years, there has been a demand for energy saving measures by weight reduction or a three-dimensional shape design, and production with thermoplastic resin such as polycarbonate (PC) based on injection molding. Is being considered. Visibility is not required to the level of the driver's seat, but when a mold with a cavity surface made of general steel is used, the optical distortion of the obtained glazing increases, and the thickness uniformity is poor. Have the problem of degrading visibility.

For the purpose of homogenizing optical distortion and thickness, it is unnecessary by suppressing the solidification when molten thermoplastic resin flows in the cavity as much as possible and reducing the filling pressure (injection pressure) during molding. It is extremely effective to form glazing using a zirconia ceramic insert which is effective in preventing the occurrence of strain due to pressure or is effective in pressure uniformity within the cavity surface. However, the glazing generally has an area of 500 cm ² or more, and often has a three-dimensional curved surface, so that it is very difficult to produce a zirconia ceramic insert.

  In Example 4, the glazing was a rear quarter window, which had a trapezoidal bottom side × top side × height = 500 mm × 400 mm × 350 mm cubic curved surface shape, and a glazing with a thickness of 5 mm was formed.

In the nesting in the fourth embodiment, specifically, the metal blocks 31A and 31B are made of SUS420J2 (HPM38 manufactured by Hitachi Metals, Ltd.) as in the first embodiment. Further, the composition of the metal base layers 32A and 32B having a thickness of 0.05 mm is Ni—Cr (more specifically, Ni-20% Cr), as in Example 1, and is made of metal based on the thermal spraying method. It is formed on the top surfaces of the blocks 31A and 31B. The surfaces of the metal blocks 31A and 31B facing the cavity 13 have a cubic curved surface shape for forming glazing. The thermal spray coatings 33A and 33B are provided on the entire surface of the metal blocks 31A and 31B facing the cavity 13. Here, in Example 4, the thermal spray coatings 33A and 33B are formed of one unit layer (ZrO ₂ ) as shown in the enlarged schematic partial sectional view of the nesting 20A and 20B in FIG. And is formed by a plasma spraying apparatus. The cavity surfaces of the inserts 20A and 20B have a mirror finish. The specific configuration and structure of the thermal spray coatings 33A and 33B are the same as the specific configuration and structure of the thermal spray coatings 33A and 33B described in the third embodiment. Here, metal films 40A and 40B are disposed on the surfaces of the sprayed coatings 33A and 33B. Specifically, after the surfaces of the sprayed coatings 33A and 33B are etched using acid, a Ni—P layer having a thickness of 100 μm is formed by an electroless plating method to obtain the metal films 40A and 40B. Finish. Thus, the metal films 40A and 40B having _a surface roughness _Ra of 0.005 μm and a mirror finished thickness of 80 μm can be obtained.

  The conditions for injection molding in Example 4 are illustrated in Table 6 below.

[Table 6]
Injection molding machine: Nissei Plastic Industry Co., Ltd. AZ7000
Thermoplastic resin: PC resin (Mitsubishi Engineering Plastics H3000R)
Resin temperature: 290 ° C
Mold temperature: 80 ° C
Injection pressure: 80 MPa

The mold has a stamping structure formed by the parting surface of the first mold part 11 and the parting surface of the second mold part 12. Then, the first mold part 11 and the second mold part 12 are clamped so that the volume of the cavity 13 is larger than the volume of the molded product to be molded (in the conceptual diagram of the mold assembly 10A). Specifically, the first mold part (fixed mold part) 11 and the second mold part (movable mold part) in a state where the thickness of the molded product becomes 1.0 mm thick. 12 was clamped. Next, a molten thermoplastic resin was injected into the cavity 13 from the molten resin injection portion 14. Then, after the completion of the injection of the molten thermoplastic resin, the volume of the cavity 13 was reduced to the volume of the molded product to be molded with a compressive force of 2.5 × 10 ³ N. A state in which the volume of the cavity 13 is decreasing is shown in FIG. 5 which is a conceptual diagram of the mold assembly, but in FIG. 5, illustration of the molten thermoplastic resin is omitted. The final thickness of the molded product was 5.0 mm. Next, the thermoplastic resin in the cavity 13 was cooled and solidified, and then the obtained molded product was released from the mold.

  Although the molten resin injection part 14 has a side gate structure with one gate point, by using the injection compression molding method, high filling property of the molten thermoplastic resin into the cavity 13 can be achieved. Moreover, since the transferability and pressure retention are excellent, there is no sink or warp in the glazing, and the glazing has a very good three-dimensional curved surface. In addition, when the glazing distortion was observed by setting the polarizing plate in a crossed Nicol state, the glazing portion corresponding to the vicinity of the molten resin injection portion 14 exhibited a color from white to black, and the distortion was very high. It turns out that there are few. Further, although molding was performed 50,000 times, no damage or the like occurred in the inserts 20A and 20B.

  In injection compression molding, when a nested insert made of a sintered body is used as in the prior art, the design of the sintered body is very difficult. When a metal plate is used as a holding plate, the metal surface of the metal plate is used as the cavity surface. In order to appear, the appearance of the molded product is impaired, or when the sintered body is formed in a box shape, there is a problem that the wall thickness is increased and the cooling time is extended. In the mold assembly of Example 4, by using a nesting composed of a metal block, a metal underlayer, and a thermal spray coating, it is not necessary to make the heat insulation uniform with a uniform thickness and use a pressing plate. There are also advantages such as simplification, prevention of breakage of the nesting, and ease of designing and manufacturing a mold assembly especially in the stamping structure.

  As mentioned above, although this invention was demonstrated based on the preferable Example, this invention is not limited to these Examples. The structure and configuration of the nesting described in the examples, the material used, the configuration and structure of the mold assembly, the injection molding conditions, and the like are examples, and can be changed as appropriate. In the embodiment, the nest is disposed in the first mold part and the second mold part. However, depending on the molded product to be molded, the nest may be disposed only in the first mold part. The nest may be provided only in the second mold part. Depending on the molded product to be molded, the entire surface of the nesting facing the cavity can be made of a sprayed coating, or a part of the surface can be made of a sprayed coating, Can be configured such that the metal block is exposed. In the embodiment, the nestings 20A and 20B have the same configuration, but may have different configurations as necessary.

1A is a schematic cross-sectional view of a nesting in Example 1, and FIGS. 1B and 1C are schematic partial cross-sectional views in which the nesting is enlarged. FIG. 2 is a conceptual diagram of the mold assembly according to the first embodiment. FIG. 3 is a conceptual diagram of the mold assembly according to the second embodiment. FIG. 4 is a conceptual diagram of a mold assembly of Example 4 immediately after mold clamping. FIG. 5 is a conceptual diagram of the mold assembly in the fourth embodiment in a state where the volume of the cavity is reduced to the volume of the molded product to be molded.

Explanation of symbols

10, 10A, 10B ... mold assembly, 11 ... first mold part (fixed mold part), 12 ... second mold part (movable mold part), 13 ... cavity , 14 ... Molten resin injection part (gate part), 15 ... Runner part and sprue part, 16 ... Injection cylinder, 17 ... Pressurized fluid injection nozzle, 18 ... Moving means, 19 ... Overflow cavity, 20A, 20B ... Nest, 31A, 31B ... Metal block, 32A, 32B ... Metal underlayer, 33A, 33B ... Thermal spray coating, 33 ', 33 "... Unit layer, 34A, 34B: generic name for metal underlayer and sprayed coating, 40A, 40B: metal film

Claims (14)

(A) A first mold part, a second mold part, and a molten resin injection part provided in the first mold part, and a cavity formed by clamping the first mold part and the second mold part. Mold formed,
(B) Nesting disposed in the first mold part and / or the second mold part, and
(C) a metal film having a thickness of 0.03 mm to 0.5 mm disposed on the surface of the nest, forming a surface constituting the cavity;
A mold assembly comprising:
Nesting is
(A) metal block,
(B) a metal underlayer having a thickness of 0.03 mm to 1 mm formed on at least the surface of the metal block facing the cavity; and
(C) a thermal spray coating made of ceramics formed on a metal underlayer;
Consists of
The thermal spray coating has a porosity that varies in the thickness direction,
The mold assembly is characterized in that the porosity is lower on the side closer to the surface of the sprayed coating. 2. The mold assembly according to claim 1, wherein a sprayed coating is formed on the entire surface of the metal block facing the cavity. 2. The mold assembly according to claim 1, wherein a thermal spray coating is formed on a part of the surface of the metal block facing the cavity. The thermal conductivity of the thermal spray coating is 1 W / (m · K) to 4 W / (m · K),
The mold assembly according to any one of claims 1 to 3, wherein an average thickness of the thermal spray coating is 0.3 mm to 2.0 mm. The average porosity of the portion from the surface of the thermal spray coating to the thickness of 0.05 mm toward the inside of the thermal spray coating is 0.4% or more and less than 5%, and it goes from the interface between the metal underlayer and the thermal spray coating to the inside of the thermal spray coating. The mold assembly according to any one of claims 1 to 4, wherein an average value of porosity in a portion up to 0.2 mm in thickness is 5% or more and 10% or less. The average particle size of the material constituting the thermal spray coating in the portion from the thermal spray coating surface to the thickness of 0.05 mm toward the inside of the thermal spray coating is 2 × 10 ⁻⁶ m to 5 × 10 ⁻⁵ m. The average particle diameter of the material constituting the thermal spray coating in the portion from the interface with the thermal spray coating to the thickness of 0.2 mm toward the inside of the thermal spray coating is 2 × 10 ⁻⁵ m to 1 × 10 ⁻⁴ m. The mold assembly according to any one of claims 1 to 4. The metal film is made of at least one material selected from the group consisting of chromium, a chromium compound, nickel, and a nickel compound, according to any one of claims 1 to 6. The mold assembly as described. 8. The mold assembly according to claim 7, wherein the metal film is formed on the sprayed coating by plating. 7. The mold assembly according to claim 1, wherein the metal film is made of a nickel-phosphorus alloy or nickel and is detachably disposed on the surface of the insert. . The mold assembly according to any one of claims 1 to 9, wherein the surface of the metal film is a mirror surface. The mold assembly according to any one of claims 1 to 9, wherein an uneven portion is formed on a surface of the metal film. (A) A first mold part, a second mold part, and a molten resin injection part provided in the first mold part, and a cavity formed by clamping the first mold part and the second mold part. Mold formed,
(B) Nesting disposed in the first mold part and / or the second mold part, and
(C) a metal film having a thickness of 0.03 mm to 0.5 mm disposed on the surface of the nest, forming a surface constituting the cavity;
A mold assembly comprising:
Nesting is
(A) metal block,
(B) a metal underlayer having a thickness of 0.03 mm to 1 mm formed on at least the surface of the metal block facing the cavity; and
(C) a thermal spray coating made of ceramics formed on a metal underlayer;
Consists of
The thermal spray coating has a porosity that varies in the thickness direction,
The porosity is an injection molding method using a mold assembly that has a lower value on the side closer to the sprayed coating surface,
(A) After the first mold part and the second mold part are clamped to form a cavity, the molten thermoplastic resin is injected into the cavity from the molten resin injection part,
(B) Cooling and solidifying the thermoplastic resin in the cavity, and then releasing the obtained molded product from the mold,
An injection molding method comprising the steps. Using a mold assembly further comprising a pressurized fluid injection nozzle in communication with the cavity,
In the step (a), a pressurized fluid is injected into the molten thermoplastic resin injected into the cavity during injection of the molten thermoplastic resin from the molten resin injection portion into the cavity, simultaneously with the injection completion, or after completion of the injection. The injection molding method according to claim 12, wherein injection of a pressurized fluid is started from an injection nozzle. (A) A first mold part, a second mold part, and a molten resin injection part provided in the first mold part, and a cavity formed by clamping the first mold part and the second mold part. Mold formed,
(B) Nesting disposed in the first mold part and / or the second mold part, and
(C) a metal film having a thickness of 0.03 mm to 0.5 mm disposed on the surface of the nest, forming a surface constituting the cavity;
A mold assembly comprising:
Nesting is
(A) metal block,
(B) a metal underlayer having a thickness of 0.03 mm to 1 mm formed on at least the surface of the metal block facing the cavity; and
(C) a thermal spray coating made of ceramics formed on a metal underlayer;
Consists of
The thermal spray coating has a porosity that varies in the thickness direction,
The porosity is an injection molding method using a mold assembly that has a lower value on the side closer to the sprayed coating surface,
(A) After the first mold part and the second mold part are clamped so that the volume of the cavity is larger than the volume of the molded product to be molded, the molten thermoplastic resin is cavityd from the molten resin injection part. Injecting into,
(B) Simultaneously with the start of injection of the molten thermoplastic resin, during injection, at the same time of completion of injection, or after completion of injection, the volume of the cavity is reduced to the volume of the molded product to be molded;
(C) Cooling and solidifying the thermoplastic resin in the cavity, and then releasing the obtained molded product from the mold,
An injection molding method comprising the steps.

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