JP5360679B2 - Thermal control mold for injection molding and manufacturing method thereof - Google Patents

Description

  The present invention relates to a high-performance plastic injection mold such as a plastic diffractive lens, and more particularly to a core mold thereof, and controls the heat conduction to equalize the cooling rate of the main part of the molded product. Thus, tact can be shortened to improve productivity, and thermal distortion can be reduced to improve molding accuracy.

When injection molding an optical element such as an optical lens or a high-quality molded product such as a thin light guide plate, the molding accuracy is reduced due to thermal distortion if cooling is not uniform.
On the other hand, the thermal distortion can be suppressed by gradual cooling of the entire molded body.
Further, when the resin filling temperature is lowered to shorten the tact time, the fluidity is lowered, the filling rate of the microcavities is lowered, and the molding accuracy is lowered.
When the fine irregularities on the surface of the molded body are high density and are transferred and molded, the molding accuracy of the fine irregularities on the surface is lowered, and the quality of the product is impaired. In order to prevent this, it is generally known to adjust (control) the heat transfer characteristics of each part, and examples thereof are described in Patent Document 1 and Patent Document 2 below.
Further, as related arts, there are those described in Patent Literature 3, Patent Literature 4, Patent Literature 5, Patent Literature 6, and Patent Literature 7.

[Prior art 1]
This prior art 1 is described in Patent Document 1, and in a method of injection molding an uneven light guide plate for a planar light source, a heat insulating layer is coated on a mold wall constituting a mold cavity of a metal mold. Using the heat-insulating layer coating mold, the thermal conductivity of each part is adjusted by partially changing the thickness of the heat insulating layer according to the difference in the partial thickness of the molded product, so that the entire cooling is even Thus, thermal distortion is reduced. This is a mold for injection molding of a thin light guide plate for a planar light source having a thin and large screen, and as shown in FIG. A thermal control layer (heat insulation layer) 104 made of polyimide resin is superimposed on a core mold 103 attached to 102, and a metal layer 105 is superimposed on the thermal control layer 104, and the surface of the metal layer 105 Is a fine rough surface for transfer, and a cavity 106 for injection molding is formed by the movable mold 102, the fixed mold 101, and the metal layer 105. The triangular thermal control layer 104 is thin at the thick part of the cavity 106 and thick at the thin part of the cavity 106.
The unevenness of the rough surface of the metal layer 105 is dense from the thick part of the cavity 106 toward the thin part.
As described above, in order to mold a molded product efficiently and with high accuracy, the thickness of the thermal control layer 104 is changed, and the cooling rate of the molded product by the cavity 106 is equalized between the thick part and the thin part. It is something that takes the means.

[Prior art 2]
What is described in Patent Document 2 is Prior Art 2, and an outline thereof is shown in FIG. A heat insulating layer (thermal control layer) having a cross-sectional shape is provided on the surface forming the cavity of the nested mold, and cooling of the molded product is controlled (controlled) in various ways according to various purposes.
That is, in the molding die in which the core die 113 is mounted on the movable die 112 and the cavity 115 for injection molding is formed with the fixed die 111, the cavity has a surface corresponding to the thin region (A). A heat control layer (heat insulating layer) 114 is provided, and the core mold 113 and the heat control layer 114 are covered with a thin metal layer 116, and the thin region (a) of the cavity 115 is moved from a thicker portion to a thinner portion. Thus, the thickness of the heat control layer 114 is increased. As a result, heat transfer from the resin injected from the right side into the cavity thick part (region (b) in FIG. 11) and flowing through the thin region toward the tip of the cavity is suppressed. High effect.
As described above, in those described in Patent Document 1 and Patent Document 2, the resin that has reached the narrow region of the cavity is cooled in the region, and its fluidity is prevented from abruptly decreasing and the filling rate is prevented from decreasing. Is.

[Prior art 3]
In the heat insulating stamper in which a pair of stampers are mounted on both surfaces facing each other in a cavity in a mold, and a heat insulating material is included in at least one of the stampers, a heat insulating effect is disclosed in Patent Document 3. By having a film thickness distribution in which the film thickness of the heat insulating material increases in the radial direction toward the outer periphery, the heat insulating effect is changed in the radial direction, and characteristics such as transferability are improved.

[Prior art 4]
In Patent Document 4, the first and second concave grooves and the first and second convex portions are formed in the outer peripheral side boundary region of the ring-shaped substrate, and the aqueous coating liquid is formed in the inner region. Apply. At this time, in order to make up for the shortage of the coating amount, the aqueous coating solution is applied to the area protruding by the distance x outside the first convex portion. A part of the coating liquid flows beyond the first convex portion, but is clogged by the second convex portion. In this way, sink marks and flow can be suppressed during drying.

[Prior art 5]
In Patent Document 5, the first and second concave grooves and the first and second convex portions are formed in the outer peripheral side boundary region of the ring-shaped substrate, and the aqueous coating liquid is formed in the inner region. Apply. At this time, in order to make up for the shortage of the coating amount, a coating film swelled outwardly in the boundary region is formed. A part of the coating liquid flows beyond the first convex portion, but is clogged by the second convex portion. In this way, sink marks and flow can be suppressed during drying.

[Prior Art 6]
In Patent Document 6, a protective layer is provided on a ring-shaped disk substrate, and the printing surface of the protective layer has a cross-section V at the inner peripheral side boundary portion and the outer peripheral side boundary portion of the ring-shaped receiving layer. A concave groove is formed, and the depth of the concave groove is equal to or greater than the film thickness of the central region of the receiving layer. When the coating liquid is applied to the printing surface and then dried, the prior drying is suppressed by the thickness of the groove, and the film thickness can be made uniform. This is relatively close to the invention according to claim 5 of the present application.

[Prior art 7]
Patent Document 7 describes that a second metal layer (a layer having a transfer surface for molding) of a heat insulating stamper (thermal control mold) is formed with a laminated structure of Cr and Ni by electrolytic plating, and has a hardness. This improves the durability of the stamper.

[Problems of the prior art]
In the above prior art 1, the thickness of the heat insulating layer is changed in order to form the uneven light guide plate in a good and efficient manner, but the heat control means is the heat control layer (heat insulating layer). ) In the lower layer of the transfer surface, and the thickness of the thermal control layer of each part is adjusted to adjust the thermal conductivity of each part. It is not easy to finely adjust the thermal conductivity. Further, when the transfer surface of the upper layer of the heat control layer is an uneven surface, it is not easy to make fine adjustments.
In addition, the above-mentioned conventional technique 2 takes a means of controlling the cavity thickness and the heat insulating layer thickness to form an uneven-thickness molded article in a good and efficient manner. Since there is nothing but the adjustment of the thermal conductivity by adjusting the thickness of the thermal control layer, it is not easy to finely adjust the thermal conductivity locally.
Moreover, in the prior art 3, although the heat insulation effect is made ideal by changing the thickness of the heat conduction material (heat insulation material) depending on the location, a method (spin) currently used for forming the heat insulation layer is used. It is not easy to change the thickness of the heat insulating material depending on the part by coating, vapor deposition, sputtering, composite plating, etc., and it is very difficult to actually form an ideal thickness distribution.

Furthermore, in the prior art 4, the prior art 5, and the prior art 6, it is effective in the case of a circle having an area with a radius of several cm ² or more, but a corner shape such as a square or a minute size of several cm ² or less. In the case of area, it is difficult to prevent film thickness fluctuations due to dry sink marks.
Furthermore, although the prior art 7 is a patent that increases the durability of the thermal control mold, the thermal conductivity of the thermal control mold is constant regardless of the location. Since the cooling time for the meat part and the thin part is different, it is difficult to mold well and efficiently.

  Therefore, the present invention makes it easy to uniform the cooling rate for the molten resin while lowering the mold temperature compared to the prior art during injection molding of a molded part having irregularities such as thick and thin portions. Further, it is an object to devise a structure of a thermal control mold capable of improving transferability and tact of a molding cycle, and to devise a manufacturing method of the thermal control mold.

[Means for Invention of Thermal Control Mold]
Means of the invention of the heat control mold are as follows (a) to (e).
(A) Thermal control molds A and B for injection molding having a structure in which a thermal control layer having a lower thermal conductivity than the metal layer is sandwiched between the first metal layer and the second metal layer,
(B) On the first metal layer mounted on the injection molding apparatus, the second metal layer has a concave portion or a convex portion that conforms to the concave shape for transfer or the convex shape for transfer ,
(C) The first metal layer of the thermal control molds A and B is formed by applying a varnish of a low heat conductive heat-resistant resin from above the concave portion or convex portion, and the thickness is changed by the concave portion or convex portion. There is a thermal control layer having a non-uniform thickness with respect to the second metal layer ,
(D) A second metal layer having a resin molding surface is laminated on the surface of the thermal control layer via a conductive layer,
(E) The resin molding surface of the second metal layer is a concave or convex transfer surface.

Further, the above heat control mold can be as follows (Claim 2).
(F) The concave portion or the convex portion on the first metal layer is a concave curved surface portion or a convex curved surface portion, and there is a step-shaped molding pattern on the convex transfer surface of the second metal layer .

[Means for Invention of Manufacturing Method of Thermal Control Mold]
Invention of the manufacturing method of a heat-control metal mold | die is as the following (a)-(f) (Claim 3).
(A) A method of manufacturing thermal control molds A and B for injection molding having a structure in which a thermal control layer having lower thermal conductivity than the metal layer is sandwiched between a first metal layer and a second metal layer. ,
(B) On the first metal layer mounted on the mounting plate of the injection molding apparatus, a concave or convex portion conforming to the concave shape for transfer or convex shape for transfer of the second metal layer is formed,
(C) Applying a varnish of a low heat conductive heat-resistant resin from above the recesses or projections of the first metal layer of the thermal control molds A and B, heat drying, and changing the thickness by the recesses or projections Forming a thermal control layer having a non-uniform thickness with respect to the second metal layer ,
(D) Next, a conductive layer is formed on the surface of the thermal control layer,
(E) Thereafter, a second metal layer is formed on the conductive layer by electrolytic plating,
(F) A concave shape for transfer or a convex shape for transfer is formed on the resin molding surface of the second metal layer.

Furthermore, the manufacturing method of the metal mold can be as described in the following (g) (Claim 4).
(G) the concave portions or convex portions on the first metal layer is a concave shape curved portion or convex curved section, forming a step-like shaped pattern transfer surface of the convex shape on the second metal layer.

Furthermore, about the manufacturing method of the said metal metal mold | die, it can carry out like following (A)-(C) (Claim 5).
(B) on the upper surface of the first metal layer, and forming a liquid reservoir having a depth greater than且one thermal control layer with a large area than the mold transfer area,
(Ii) the varnish of the low thermal conductive heat-resistant resin in the state dissolved in Solvent to the liquid reservoir from by the desired amount ejection and the solvent was removed by drying to form a resin layer serving as the heat control layer,
(C) After that, the resin layer raised by sink marks at the time of solvent drying and removal and the outer peripheral wall surface of the liquid reservoir part are shaved together to flatten the surface of the thermal control layer.
Further, the following (d) can be made (claim 6).
(D) When the shallowest depth of the outer peripheral portion of the liquid reservoir is d, the desired resin thermal control layer depth is D, and the solvent content of the resin varnish is Pvol%,
1.5 * (D / (100-P) * 0.01)>d> D / (100-P) * 0.01
The shallowest depth d of the outer peripheral portion of the liquid reservoir is defined so that

The effects of the present invention are summarized as follows for each claim.
[Invention of Claim 1]
In the invention according to claim 1 (the above-mentioned “means of the invention for heat control mold”), since the heat control layer having high heat insulation is interposed between the first metal layer and the second metal layer, the heat The thickness of the control layer can be easily adjusted locally, such that the part that contacts the thick part of the molded part is thin and the part that contacts the thin part is thick. There is a heat control function by both of the heat control layers, and the combination of the two makes it possible to freely and finely control (control or adjust) the local heat transferability.
Thereby, the cooling rate of the thick part and the thin part of the molded part can be finely adjusted to be substantially uniform. Therefore, the thermal distortion of the molded product can be reduced, the transferability such as the birefringence and mechanical properties of the molded part can be improved, and further, the decrease in resin fluidity at the end of the fine pattern is reduced. As a result, the mold temperature can be greatly reduced, and the molding tact time can be shortened.
In addition, the molded part manufactured by the above-described heat control mold has high quality because it has less thermal distortion and high transfer molding accuracy.

[Inventions according to claims 2]
The invention according to claim 2, in particular the second metal layer on the convex portion on the first metal layer, since is formed a step-like shaped pattern of convex, it exhibits the following unique effects.
That is, since the convex part according to the convex shape of the 2nd metal layer is formed on the 1st metal layer, the change of the cooling state by the difference in the thickness of the 2nd metal layer resulting from the difference in the height of the transfer shape , the thickness of the thermal control layer and the first metal layer is adjusted, not out variation in transferability, it is possible to obtain good transferability.

[Invention of Claim 3]
The invention according to claim 3 (the above-mentioned “means of the invention of a method for producing an object” is the formation of a heat control layer by a varnish of a low heat conductive heat-resistant resin after forming a concave or convex portion on the first metal layer in advance. Therefore, the mold of the invention according to claim 1 (mold having a desired thermal conductivity distribution) can be manufactured easily and with high accuracy, and the molding process can be performed with a short tact. Can be repeated, so productivity is high.
Furthermore, it is possible to cope with fine and complicated transfer shapes.

[Invention of Claim 4]
Since the invention according to claim 4 adopts the configuration of the manufacturing method according to claim 3, in addition to the effects described above, the following specific effects can be obtained.
That is, the mold of the invention according to claim 2 can be manufactured easily and with high accuracy .

[Invention of Claim 5]
The invention according to claim 5, the upper surface of the first metal layer, forming a且one greater than the thermal control layer depth of the liquid pool portion in larger area than the die transfer area, dissolved in Solvent in the liquid reservoir After discharging a desired amount of the varnish of the low heat conductive heat-resistant resin in the state of being dried, the solvent is dried and removed to form a resin layer, and then the outer periphery of the resin layer and the liquid reservoir portion swelled by sink marks when the solvent is removed by drying and planarizing the cutting Rinetsu control layer surface walls together, Therefore, the thickness unevenness of the thermal control layer is suppressed, the optical, transferability may moldable thermally controlled mold excellent diffractive lens mechanical properties Can be manufactured.

[Invention of Claim 6]
In the invention according to claim 6, when the shallowest depth of the outer peripheral portion of the liquid reservoir is d, the desired resin thermal control layer depth is D, and the solvent content of the resin varnish is Pvol%,
1.5 * (D / (100-P) * 0.01)>d> D / (100-P) * 0.01
Since the shallowest depth d of the outer peripheral portion of the liquid reservoir portion is defined so that the relationship of the above is satisfied, even if a resin varnish having a discharge amount that allows for the amount of solvent that is reduced by drying and curing is discharged to the liquid reservoir portion, In addition, the resin varnish does not overflow from the liquid reservoir, and the removal of the end of the liquid reservoir in the next process can be performed efficiently and in a short time.

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(A) is a plan view of a diffractive lens molded by the mold of the embodiment, (b) is an end view of the diffractive lens, and (c) is a side view of the diffractive lens. Is a production process diagram showing the first half of the production process of mold A Is a production process diagram showing the first half of the production process of mold B Is a production process diagram showing the second half of the production process of mold A Is a production process diagram showing the second half of the production process of mold B FIG. 3 is a cross-sectional view schematically showing a cross-sectional structure of an injection molding apparatus using molds A and B Is a manufacturing process diagram according to another method for forming the thermal control layer of the molds A and B Is a sectional view of molds A and B in the embodiment of FIG. Fig. 7 is a sectional view of a thermal control mold according to the embodiment of Fig. 7 Is a sectional view for explaining the prior art Is a sectional view for explaining another prior art

The configuration and manufacturing method of the thermal control mold according to the invention will now be described while showing the forming of the diffractive lens as a real施例.
Summary of the diffractive lens 1 of this embodiment is as shown in FIG. 1, the shape, the entire body is a cylindrical lens shape. A stepped diffraction pattern is engraved in the widthwise direction on the concave side. A convex side in the longitudinal Direction linear shape, Tantekata direction has a convex shape.

The mold is formed by sandwiching the concave portion 2 and the convex portion 3 of the diffractive lens 1 from both sides, and two thermal control molds A and thermal control molds B are manufactured as one set. The concave portion 2 of the diffractive lens 1 is molded by a thermal control mold A (hereinafter simply referred to as “mold A”), and the convex portion 3 is molded by a thermal control mold B (hereinafter simply referred to as “mold”). Mold B)). Specific dimensions of the diffractive lens 1 are approximately 12 mm in the longitudinal direction, approximately 4 mm in the lateral direction, and approximately 3 mm in lens thickness. The step pattern has a height of 1.5 μm step by step. The step width is about 200 μm at the center and gradually narrows toward the end, and about 10 μm at the end. The number of steps is about 100, and the depth of the recess 2 as a whole is about 150 μm. The convex portion 3 of the diffractive lens 1 has an aspherical shape (arc shape) with a radius of curvature (R) of about 25 mm.
The mold A is composed of the first metal layer A1, the thermal control layer 30, and the second metal layer A2 (FIG. 4C), and the mold B is similarly composed of the first metal layer B1 and the thermal control layer 30. This is due to the second metal layer B2 (FIG. 5C). These molds A and B are molded by the following steps 1-6.

1. Formation of the first metal layers A1, B1:
Forming a convex portion 10 which is similar to the upper surface of the first metal layer A1 in the recess 2 of the diffraction lens 1 of the mold A to be mounted on the injection molding apparatus (FIG. 2 (a)), also a first mold B A concave portion or a convex portion 20 similar to the convex portion 3 of the diffraction lens 1 is formed on the upper surface of the metal layer B1 (FIG. 3A). The material of the first metal layer A1 and the first metal layer B1 only needs to be excellent in workability and relatively high in hardness, and for example, SK material, SKH material, STAVAX, or the like can be used.
Although the step corresponding to the step of the diffractive lens concave portion 2 on the surface of the second metal layer A2 convex 51 of the mold A is formed, the step on the surface of the convex portion 10 of the first metal layer A1 Is not formed.
The mold A side has a convex lens shape on the short side with a top height of 15 μm, and the mold B side has a concave lens shape on the short side with a bottom depth of 15 μm. This is because if the shape of the depth or height of the first metal layer is simply set to the shape of the same height or depth as the transfer surface of the second metal layer, thermal control will be performed when the thermal control layer 30 is formed later. The difference between the thickest part and the thinnest part of the layer thickness is 100 μm or more, but since there is a big difference in thermal conductivity between the low thermal conductive heat-resistant resin as the thermal control layer 30 and the metal, so far If the thickness of the heat control layer 30 is greatly different, the way heat is transferred from the molded product varies greatly depending on the location. For example, the thin part of the heat control layer has already been cooled. This is because the moldability is adversely affected by the problem that cooling is not yet completed in the thick part of the heat control layer.
The molds A and B are both linear in the longitudinal direction.

The convex portion 10 of the first metal layer A1 and the concave portion 20 of the first metal layer B1 are formed by precision cutting. The machining dimension is counterbore processed to be slightly larger than the diameter of the arc-shaped unevenness of the diffractive lens, and a convex part (FIG. 2 (a)) or a concave part (FIG. (A)) is formed. The surface of the first metal layers A1 and B1 is subjected to a surface etching process (not shown) by a dry method (or a wet method) in order to improve the adhesion with the heat control layer 30 (varnish). Further, the forming process of the upper surfaces of the first metal layers A1 and B1 is not limited to precision machining because it is only necessary to precisely process the convex part 10 or the concave part 20, and physical or chemical processing (wet process). Other methods such as dry etching and deposition) can also be used.

2. Formation of thermal control layer:
The heat control layer forming material on the upper surfaces of the first metal layers A1 and B1 is a polymer material, a ceramic material, or a metal material having properties such as low thermal conductivity and high heat resistance. Specifically, polyimide or polyamideimide as a polymer material, zirconia as a ceramic material, bismuth as a metal material, and a composite plating film obtained by eutecting a filler or fine particles of a low thermal conductive material. Is available. However, among these, in order to laminate ceramic materials, a sintering temperature of 1000 ° C. or higher is required, and bismuth has low rigidity and is brittle and the surface roughness during film formation is rough, so when actually used. Therefore, appropriate examination is required. In view of the above, in this embodiment, a polyamide-imide resin varnish (trade name) having a low thermal conductivity (about 0.5 W / m · K), a high heat resistance (about 300 ° C.) and a relatively easy handling. : Toyobo's Viromax) is used to form the thermal control layer 30.

The convex portions 10 or the concave portions 20 of the molds A and B are completely covered with the thermal control layer 30, and the thermal control layer 30 is a coating layer having a predetermined thickness except for the convex portions 10 or the concave portions 20. And its surface is a flat surface.
The thermal control layer 30 is formed as follows. That is, a required amount of the resin varnish is dropped by a precision dispenser (FIG. 2 (b), FIG. 3 (b)), then left for a certain time (about 180 seconds in this example), and then heated and dried (200 ° C. , 40 minutes). When the resin varnish is dripped, the resin varnish at the end of the counterbore rises slightly due to surface tension (FIGS. 2 (c) and 3 (c)), but this part is not a molded part of the diffractive lens. Moreover, since it is covered with the following second metal layers A2 and B2, there is no particular problem.

  The thickness of the thermal control layer 30 is 15 μm at the top of the convex portion (the portion corresponding to the concave portion of the diffractive lens) 10 of the mold A, and 30 μm in the thickness of the other flat portion. 45 μm at the bottom of the portion corresponding to the recess) and 30 μm at the other flat portions. By making such a thickness distribution, the thermal conductivity of the mold part that hits the thick part of the diffractive lens is increased, and conversely, the thermal conductivity of the thin part is lowered, thereby cooling the molded diffractive lens. Becomes uniform.

3. Conductive film pre-treatment:
Pretreatment for increasing the adhesion strength with the conductive layer formed in the next step, that is, pretreatment for forming a conductive layer (hereinafter referred to as “conductive film”) is performed on the surface of the thermal control layer 30. This is a pretreatment for forming a conductive film (FIGS. 2D and 3D). In this embodiment, the atmospheric pressure plasma surface treatment method is adopted. However, the adoption of the atmospheric pressure plasma treatment is a simple method, but can increase the activity of the resin surface and has a long effect. Because it lasts for hours. By this treatment, 6 to 8 times the adhesion strength (about 25 N / cm) can be obtained as compared with the case of no treatment (about 3 to 4 N / cm).
In addition, there are oxygen plasma etching treatment, ultraviolet ray / ozone treatment, etc. as the pretreatment method for forming the conductive film. However, unless the parameters such as oxygen concentration and treatment time are optimized, the adhesion strength is reduced. It will be difficult to handle. On the other hand, the atmospheric pressure plasma surface treatment method is excellent because it does not do so.

4). Conductive film formation treatment:
A conductive film is formed on the surface of the heat control layer that has been subjected to the pretreatment of the conductive film. Conductive film formation methods include sputtering methods and ion plating methods of conductive materials using argon gas, etc., as well as metal vapor deposition methods and electroless plating methods, which can be used, but considering the problem of interfacial delamination, It is desirable to use a sputtering method or an ion plating method in which metal particles penetrate deeply into the object and have high film adhesion. The sputtering method can form a uniform film over a wide area, and the ion plating method can obtain higher adhesion by accelerating the ejected atomic molecular particles by applying an electric field. .

In this example, a method of forming a film of nickel of the same material as the second metal layers A2 and B2 as a material of the conductive film by sputtering of argon gas was employed, and nickel was formed by DC sputtering of argon gas. And thin film formation was implemented by ultimate vacuum degree: 2-8 * 10 <-3> Pa, argon leak pressure: 0.3-1.5Pa, DC power: 200-700W. If the film thickness is less than 20 nm, film formation becomes difficult, and if it exceeds 200 nm, cracks due to internal stress occur. Therefore, in this example, the film thickness was set to 100 nm ± 50 nm (FIGS. 4A and 5A ).

5. Second metal layer formation:
Second metal layers A2 and B2 (FIGS. 4A and 5A) are formed on the work on which the conductive film 40 is formed by nickel electroplating. An outline of the electrolytic plating bath is shown in Table 1.

ワークを入槽してから３分〜５分間、０．２Ａ／ｄｍ２未満の弱電流密度で通電し、導電皮膜をニッケル電鋳液に馴染ませて濡れ性を向上させ、ピット発生や電鋳時剥離を防ぐようにする。弱通電終了後に通電電流値を上昇させ、最終的に、１０Ａ／ｄｍ２〜２０Ａ／ｄｍ２程度まで電流値を上昇させてから一定に保ち、所定の電鋳膜厚（２００〜２５０μｍ程度）を得るまで通電を続ける（図４（ｂ）、図５（ｂ））。

Energized with a weak current density of less than 0.2 A / dm2 for 3 to 5 minutes after entering the work tank, adapting the conductive film to the nickel electroforming solution, improving wettability, and generating pits and electroforming Try to prevent peeling. Energizing current value is increased after the end of weak energization, and finally the current value is increased to about 10 A / dm2 to 20 A / dm2 and then kept constant until a predetermined electroformed film thickness (about 200 to 250 μm) is obtained. The energization is continued (FIGS. 4B and 5B).

6). Molding pattern formation:
After forming the second metal layers A2 and B2, a convex shape 51 or a concave shape 52 corresponding to the shape of the diffractive lens (see FIG. 1) is formed on these second metal layers, and the convex surface A stepped diffractive lens molding pattern is formed on the substrate. These forming methods are performed by precision cutting as in the forming process of “1. Formation of first metal layers A1 and B1 ” (FIGS. 4C and 5C).

The molds A and B having the heat control structure are manufactured by the processing steps 1 to 6 described above.
The heat control of the mold is based on the heat transfer resistance of the first metal layers A1 and B1, the heat transfer resistance of the heat control layer (heat insulating layer) 30, and the heat transfer resistance of the second metal layers A2 and B2. Among them, the adjustment of the partial heat transfer resistance of the heat control layer 30 is made through the difference in thickness of the heat control layer 30 resulting from the difference in the concave or convex shape formed on the first metal layers A1 and B1. Therefore, thermal control in the thickness difference of the molded product becomes easy. Therefore, as compared with the conventional one, the heat control of a mold having a transfer surface having a complicated shape is easy, and the mold can be easily manufactured.

Next, injection molding of a diffractive lens using these molds will be described (see FIG. 6).
A mold A and a mold B are detachably mounted on and fixed to a movable mold 71 and a fixed mold 72 of an injection molding apparatus, respectively, and a molten resin is filled in a cavity formed by both molds A and B, and a fixed mold. The mold 72 and the movable mold 71 are pressurized. Then, after cooling to a predetermined temperature, the fixed mold 72 and the movable mold 71 are separated and the molded product is taken out.

  In this embodiment, even if the heating temperature of the molds A and B is lowered by 20 to 30 ° C. compared to the case of using the conventional mold, the resin during the resin filling is maintained at a temperature higher than the temperature at which the fluid state can be secured, and the microstructure The part is sufficiently filled. Thus, since the mold temperature is 20 ° C. to 30 ° C. lower and there is no problem in filling the fine shape, the time required to cool the mold to the take-out temperature is shortened, and therefore the molding tact time is reduced. Shortened. That is, in the case of using a conventional mold, the molding tact is about 2 minutes, whereas in this embodiment, it is 1 minute or less, so that the molding tact is shortened by about 1 minute or more. If the diffractive lens is molded with a thermal control mold having a uniform thickness of the thermal control layer 30, the cooling state is different between the thick part and the thin part of the molded product, so that the birefringence of the molded product increases. In the case of the molds A and B of this embodiment, the thickness of the thermal control layer is adjusted according to the difference in the thickness of the molded product, and molding is performed. Since the product cooling time can be made uniform, birefringence can be suppressed to ± 100 nm.

[Second Embodiment]
In addition to the above-described embodiments, the first metal layer and the thermal control layer are formed by the following method, so that a diffractive lens having more excellent optical characteristics and mechanical characteristics can be molded with good transferability. An example thermal control mold can be manufactured. This will be described in the following steps (1) to (3). However, since the steps after this step are the same as steps 4 to 6 for the above-described embodiment, description thereof will be omitted, but finally, the heat having a cross-sectional shape as shown in FIG. Control mold is produced. However, in FIG. 7A to FIG. 7E and FIG. 9, the illustration of the convex portion or the concave portion on the first metal layer actually in the molds A and B is omitted.

(1) First metal layer formation:
Die A which is mounted on the mounting plate of the molding apparatus, the first metal layer on the B, convex portions corresponding to the transfer surface of the second metal layer surface (mold A) and forming a recess (die B) ( FIG. 2 (a) and FIG. 3 (a) ). The material of the first metal layer may be any metal material that has good workability and relatively high hardness. For forming the diffractive lens, a step corresponding to the concave part of the diffractive lens is formed on the convex transfer surface of the second metal layer surface of the mold A, but such a fine shape is formed on the surface of the first metal layer. It is not necessary to form, and a mold corresponding to a macro lens shape is formed. However, the dimension of the lens shape is such that the mold A side has a convex lens shape on the short side with a top height of 15 μm, and the mold B side has a concave lens with a bottom depth of 15 μm on the short side. The shape of In the longitudinal direction, both molds A and B are linear. If the shape is simply the same depth as the transfer surface of the second metal layer, the difference between the thickest part and the thinnest part of the heat control layer thickness will be 100 μm or more when the heat control layer is formed later. For this reason, the way heat is transmitted from the molded product varies greatly depending on the location, which adversely affects the moldability.

In the second embodiment, machining such as precision cutting is employed as a forming method, but grinding or the like can also be used. As a processing procedure, a liquid reservoir having a size that is slightly larger than the transfer area of the diffractive lens is formed so as to be spotted (see FIG. 7A), and a convex portion corresponding to a shape corresponding to the shape of the diffractive lens is formed at the center ( A mold A) and a recess (mold B) are formed (not shown).
The shallowest depth d of the outer peripheral part of the liquid pool part is defined as D for the desired thermal control layer depth and Pvol% for the solvent content of the resin varnish.
1.5 × (D / (100−P) × 0.01)>d> D / (100−P) × 0.01 is set (see FIGS. 7E and 8). . By setting the shallowest depth d of the outer peripheral portion of the liquid reservoir in this manner, even if the amount of the resin varnish expected to be reduced by drying and curing is discharged to the liquid reservoir, the resin varnish remains in the liquid reservoir. And the removal of the liquid pool end in the next process can be performed efficiently and in a short time.
The surface of the first metal layer is subjected to a surface etching process (not shown) by a dry or wet method in order to improve adhesion with the heat control layer.

(2) Thermal control layer formation:
The thermal control layer is formed on the first metal layer (1). Thermal control layer forming materials include polyimide and polyamideimide as polymer materials, zirconia as ceramics, bismuth as metals, and composite plating films in which fillers and fine particles of low thermal conductivity materials are co-deposited. Is possible. However, among these, in order to laminate ceramic materials, a sintering temperature of 1000 ° C. or higher is required, and bismuth has low rigidity and is brittle and the surface roughness during film formation is rough, so when actually used. Therefore, appropriate examination is required.

In view of the above, in the second embodiment, a polyamide-imide resin varnish (trade name: Viromax manufactured by Toyobo) is used as a forming material. Set after drying and curing, taking into account the amount of solvent that is completely filled in the protrusions and recesses on the first metal layer of the molds A and B, and reduced by drying and curing in advance, and removal by machining in the next process. exceed the thermal control layer thickness, and the resin varnish in an amount so as not to overflow from the liquid reservoir, it is added dropwise a constant amount by the precision dispenser (see FIG. 7 (b)).
After dropping, the resin varnish is allowed to diffuse for a certain period of time and diffuse throughout the liquid reservoir (see FIG. 7C). Even when the resin varnish is dropped and diffused, if the viscosity of the resin varnish is high, the surface of the resin varnish may not be flat and the height may be uneven (see FIG. 7C). This height unevenness may remain even if the solvent in the resin volatilizes and shrinks in volume due to drying in the next step (see FIG. 7D), but is finally flattened by machining. No problem.
After completion of the diffusion, the resin varnish is heated and dried (200 ° C., 40 minutes) to form a heat control layer (see FIG. 7D).

(3) Removal of the outer peripheral portion of the liquid reservoir and planarization of the surface of the thermal control layer:
When the drying and curing of the resin varnish of the above (2) is finished, the outer peripheral portion of the liquid reservoir and the resin thermal control layer are simultaneously machined to scrape to the set thickness of the resin thermal control layer and flatten (FIG. 7 (e) )reference).
Machining is performed by grinding or cutting, burr balls Ri outer peripheral portion liquid when the cutting work for the metal is due to the possibility of cutting into the resin thermal control layer side, it is recommended to perform in grinding . Further, if the processed surface is not mirror-finished but has a satin finish, the surface area increases accordingly, so that the adhesion is increased when the next conductive film is formed.
When the diffractive lens is molded using the thermal control mold according to the present invention, the molding tact time is about 30 seconds, and when the diffractive lens is molded using a conventional mold, the molding tact is about 3 minutes or more. Therefore, productivity is improved 3 to 6 times.

A, B: Mold (thermal control mold)
A1: first metal layer B of mold A 1: first metal layer A2 of mold B: second metal layer B2 of mold A: second metal layer B of mold B 1: diffractive lens 2: concave portion of diffractive lens 3: Convex part 10 of the diffractive lens 10: Convex part 20: Concave part 30: Thermal control layer 40: Conductive film 51: Convex shape 52: Concave shape

Japanese Patent No. 3884105 Japanese Patent Laid-Open No. 10-016009 JP 2003-80567 A JP 2007-172673 A JP 2007-168087 A Japanese Patent Laid-Open No. 2004-355781 Japanese Patent Laid-Open No. 2008-221783

Claims (6)

Thermal control molds A and B for injection molding having a structure in which a thermal control layer having a lower thermal conductivity than the metal layer is sandwiched between a first metal layer and a second metal layer,
The injection molding apparatus in the first metal layer to be mounted has a concave or convex portion conforms to transfer concave or transfer convex shape of the second metal layer,
The heat control molds A and B are formed by applying a varnish of a low heat conductive heat-resistant resin from above the recesses or projections of the first metal layer of the first metal layer , and the thickness is changed by the recesses or projections. There is a thermal control layer with a non-uniform thickness for the two metal layers ,
A second metal layer having a resin molding surface is laminated on the surface of the heat control layer via a conductive layer,
A heat-control mold for injection molding, wherein the resin molding surface of the second metal layer is a concave or convex transfer surface. The recesses or projections on the first metal layer is a concave shape curved portion or convex curved portion, claims, characterized in that there is step-like shaped pattern transfer surface of the convex shape of the second metal layer 1. Thermal control mold for diffractive lens injection molding. Between the first and second metal layers, the thermal control mold A for injection molding having the metal across the low thermal conductivity of the thermal control layer than layer structure, a manufacturing method of B,
The injection molding apparatus in the first metal layer to be attached, to form a concave or convex portion conforms to transfer concave or transfer convex shape of the second metal layer,
From above the recesses or projections of the first metal layer of the thermal control molds A and B, a varnish of a low heat conductive heat-resistant resin is applied and dried by heating, and the thickness is changed by the recesses or projections and the above Forming a thermal control layer having a non-uniform thickness with respect to the second metal layer ;
Next, a conductive layer is formed on the surface of the thermal control layer,
Thereafter, a second metal layer is formed on the conductive layer by electrolytic plating,
A method for producing a heat-control mold for injection molding, wherein a concave shape for transfer or a convex shape for transfer is formed on a resin molding surface of the second metal layer. Concave or convex portion on the first metal layer becomes concave shape curved portion or convex curved portion, claim 3, characterized in that to form a diffraction shape pattern on the transfer surface of the convex shape of the second metal layer Manufacturing method of heat control mold for diffractive lens injection molding. The top surface of the first metal layer, and a large area than the die transfer area to form a liquid reservoir portion having a depth greater than the thermal control layer, the low thermal conductive heat state dissolved in Solvent in the liquid reservoir the varnish of the resin were allowed to desired amount ejection and the solvent was removed by drying to form a resin layer serving as the heat control layer, the outer peripheral portion of the subsequently the resin layer raised by shrinkage during solvent drying and removing the liquid reservoir 4. The method for producing a heat control mold according to claim 3, wherein the wall surfaces are cut together to flatten the surface of the heat control layer. The shallowest depth of the liquid reservoir portion outer peripheral portion d, D the desired resin thermal control layer depth, and PVOL% solvent content of the resin varnish Then, 1.5 × (D / (100 -P) × 0 .01)>d> D / (so that 100-P) × 0.01 relation, thermal control of claim 5, characterized in that defining the shallowest depth d of the liquid reservoir outer peripheral portion Mold manufacturing method.

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