JP2001277253A - Mold for molding resin-molded part and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding for molding a resin-molded part which can form a molding area for molding a molded part easily in a prescribed shape and is excellent in precision and durability and a method for producing the mold. SOLUTION: In the mold in which the molding area is constituted of a cavity insert, the cavity insert 10 has a base part 13 and a plated part 12 formed on its surface by an electrocasting method, and the plated part is provided with the molding area 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding a resin molded product used for molding an optical element such as a light guide plate having a diffraction grating and / or a mirror surface, and a method for producing the same. is there.

[0002]

2. Description of the Related Art Conventionally, an edge light type light guide plate used for back lighting of a liquid crystal display is, for example, shown in FIG.
The light guide plate substrate shown in FIG. In FIG. 8, the light guide plate substrate 1 is, for example, about 1 inch square to 17 inch square.
It is composed of a transparent plate of acrylic resin or the like having a thickness of about several square inches or more and having a thickness of the order of several millimeters. Have been. The V-grooves 2 are formed, for example, with a groove pitch P of 0.3 mm and a groove depth D of 0.015 mm. Actually, about several hundred grooves are arranged.

According to the light guide plate substrate 1 having such a configuration,
When light enters the light guide plate substrate 1 from one end surface, the incident light travels inside the light guide plate substrate 1 toward the other side, and is reflected by each V-groove 2, so that the light guide plate is The light is emitted from the lower surface of the substrate 1 to the outside to illuminate, for example, a liquid crystal display device or the like disposed therebelow.

Here, the light guide plate substrate 1 is, for example, shown in FIG.
It is manufactured as shown in FIG. That is, in FIG. 9A, a base material 3 made of copper or phosphor bronze is prepared as a material having excellent machinability, and its upper surface 3a is mirror-finished as a reference surface. Then, as shown in FIG. 9B, the groove 5 is cut on the upper surface 3 a of the base material 3 by the single crystal diamond bite 4. The groove 5 has the same shape as the cutting edge of the diamond cutting tool 4. When a groove shape different from the cutting edge shape of the diamond bite 4 is to be formed, one of the cutting edge surfaces of the diamond bite 4 as shown in FIG. 9B is used alternately.

[0005] Next, as shown in FIG. 9 (C), the base material 3 having been subjected to the groove processing is made of Ni by electroforming.
Layer 6 is laminated. Thereafter, the Ni layer 6 is peeled off from the base material 3 and, as shown in FIG. 9 (D), by cutting off the hatched portions, the outer shape is processed into a predetermined shape. Thus, the metal mold 7 by electroforming is completed. By performing resin molding using such a mold 7 as a master, the light guide plate substrate 1 provided with the V-groove 2 corresponding to the groove portion 5 is completed.

[0006]

By the way, the Ni layer 6 formed by the electroforming method in such a method of manufacturing a molding die is generally required to have a thickness on the order of several mm. For this reason, it takes several days to ten and several days only in the electroforming process, and the yield is low.
There is a problem that it is difficult to supply a stable mold. Further, the accuracy of the mold 7 made of the Ni layer 6 with respect to the master is surely degraded and the surface hardness is low. Therefore, the mold 7 is scratched during the assembly, and the life of the mold 7 during injection molding is short. There were also problems such as.

On the other hand, an electroless Ni-
A mold manufacturing method in which a P-plated film is formed and a groove is directly cut in the plated film is already known. For example, as shown in FIG. 10, the electroless Ni-P plating contains a processing solution including a sodium hypochlorite solution as a reducing agent, nickel sulfate as a metal salt, sodium citrate as a complexing agent, and the like. The work is performed by immersing the base material 3 as a work in the treated tank.

However, in the case of electroless Ni-P plating, even if the surface of the substrate to be plated is pretreated with a catalyst such as palladium, the adhesion strength of the plating film to the substrate is low. Sufficient attention must be paid to peeling of the plating film at the time of the next processing, and the workability is deteriorated. Further, since the adhesion strength is low, generally, when the thickness of the plating film exceeds about 0.1 mm, the plating film often peels off from the base material due to film stress.
There is a problem that it is not suitable for forming a plating film having a thickness of not less than mm. Further, in the treatment by the electroless Ni-P plating, it is difficult to control the content of P (phosphorus),
The content of P is generally only about 2 to 8%. But,
Ni-P plating for cutting is desirably about 10% or more, and electroless Ni-P plating having a P content of only about 2 to 8% is an unstable process that causes variation in workability. Would.

That is, as shown in FIG. 11, for example, when a tool 8 is used to leave a crest of about 100 μm in height with a top of 60 degrees on the electroless Ni—P plating film 7 using a tool 8, Burrs occur at the vertex 7b. As shown in the graph of FIG. 12, the size of the burrs changes according to the phosphorus content of the plating film 7, and it can be seen that the burrs become smaller as the phosphorus content increases. However, in the electroless Ni-P plating, chemical treatment is performed by a reaction in the treatment liquid, and the phosphorus content of the treatment liquid changes sequentially. Therefore, it is difficult to control the phosphorus content. Since it is about 2 to 8%, large burrs are generated and there is a problem that workability is poor.

On the other hand, as shown in FIG. 13A, a substrate made of copper, phosphor bronze or the like is used, and as shown in FIG. There is also a method of forming the groove 2. However, as described above, there has been a problem that burrs are generated at the tops of the hills, and machining defects due to the constituent cutting edges caused by the soft material frequently occur.

SUMMARY OF THE INVENTION In view of the above, the present invention makes it possible to easily form a molding region for molding a molded part into a predetermined shape, and to form a molding metal for a resin molded part with high precision and excellent durability. It is an object to provide a mold and a method for manufacturing the mold.

[0012]

According to the first aspect of the present invention, there is provided a mold for molding a resin molded part, wherein a molding region for molding the resin molded part is formed by nesting. The nest has a base and a plating part formed on the surface by electroforming, and the plating part is provided with a molding region for molding the molded part. This is achieved by a molding die.

According to the above construction, the nest is a base,
It has a plating part formed by an electroforming method on its surface, and since this plating part is provided with a molding area part for molding the molded part, there are cases where the nest consists only of the plating part. In comparison, the precision is less likely to deteriorate with respect to the master. Further, since the plated portion is formed by the electroforming method, it is easy to configure the thickness of the plating up to, for example, about 1 mm. According to the electroforming method, the nest can be easily formed in a relatively short time, the yield can be improved, and the nest can be supplied stably.

Preferably, according to a second aspect of the present invention, in the configuration of the first aspect, the molding metal for a resin molded component, wherein the molding region is a groove and / or a mirror surface provided by cutting or polishing. Type.

According to the above configuration, the molding region is a groove and / or a mirror surface provided by cutting or polishing. Therefore, by directly cutting or polishing the plated portion, the groove portion and / or the mirror surface portion can be formed with high precision.

Preferably, according to a third aspect of the present invention, in the configuration of the first aspect, the base portion is made of a high-hardness base material made of martensitic stainless steel or cemented carbide, and the plating portion is made of electric Ni. -A mold for molding a resin molded part made of a P plating film.

According to the above construction, since the base is made of a high-hardness base material made of martensitic stainless steel or cemented carbide, the material is the same as that of the mold body, and the coefficient of linear expansion is substantially equal to that of the mold body. Matching makes the whole mold design easier. In addition, by selecting such a material, resin molding at a high temperature using a mold becomes possible, the occurrence of resin overlap and burrs, etc. is reduced, and deterioration in the quality of molded products can be minimized. . In particular, when the material of the mold body is carbon steel for general mechanical structure, it is easy to form the base member into the same material. Further, the plating portion is made of electric Ni.
-Since it is composed of a P plating film, the content of P is, for example, 10%.
Since it can be easily performed as described above, it is easy to perform processing such as cutting on the plated portion, and it is difficult for burrs and returns to occur at the edge portion.

Preferably, according to a fourth aspect of the present invention, in the configuration of the second aspect, there is provided a mold for molding a resin molded part in which the surface of the groove and / or the mirror surface is subjected to high hardness treatment.

According to the above configuration, since the surface of the groove and / or the mirror surface is subjected to a high hardness treatment, damage to the plating portion of the nest can be reduced when the nest is assembled with the molding die. This contributes to prolonging the service life and can sufficiently withstand high injection pressure.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a mold for molding a resin molded part, wherein a molding region for molding the resin molded part is formed by nesting. Production of a molding die for a resin molded part, comprising: a step of forming a plated part on the surface of the base part by an electroforming method; and a step of forming a molding area part for molding the molded part on the plated part. Achieved by the method.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. still,
Since the embodiments described below are preferred specific examples of the present invention, various technically preferred limitations are added.
The scope of the present invention is not limited to these embodiments unless otherwise specified in the following description.

FIG. 1 is a schematic perspective view showing a nest 10 used for a light guide plate substrate molding die according to an embodiment of the present invention. In FIG. 1, a nest 10 is for forming a so-called backlight light guide plate for performing backlighting of a liquid crystal display device, for example. The nest 10 can also be used to form a front light guide plate for performing front illumination of the liquid crystal display device. As shown in FIG. 1, the nest 10 has a length (L) of 200 mm and a width (W) of 3, for example.
It has a size of 00 mm, and a plurality of V-grooves 11 as grooves are formed on the upper surface thereof. This V groove 11
Is a portion for forming a diffraction grating and a mirror surface portion of the formed light guide plate. Therefore, although eight V-grooves 11 are formed in FIG. 1, about 1,000 are actually formed. V-groove 1 thus formed
1 is configured such that its pitch and depth gradually increase from the left side in FIG. Specifically, V is changed so that the depth changes from 0.01 mm to 0.3 mm.
The grooves are arranged side by side. The V groove 11 is formed in the plating film 12 described later, and the plating film 12 is formed on the surface of the base material 13 described later.

The nest 10 thus constructed is manufactured as follows. First, as shown in FIG. 2A, a base material 13 which is a base made of martensitic stainless steel or cemented carbide is prepared. This is generally the same material as the material of the mold body 40 for precision injection molding.
Here, the mold bodies 40 are used in a molding machine 30 as shown in FIG. FIG. 5 is a schematic diagram showing the entire molding machine 30 including a partial cross section (a portion between break lines). The molding machine 30 is provided with a resin inlet 3 for charging a resin.
1, a cylinder 32, a fixed mold plate 33a and a movable mold plate 33b. The mold body 40 is placed on the movable mold plate 33b.
A nest 10 described later is arranged. On the other hand, the mirror insert 50 is arranged on the fixed-side template 33a. In this state, as shown in FIG.
By moving 0 in the direction of the arrow, the light guide plate is formed as shown in FIG. FIG. 6 shows the insert 10 and the mold body 40 viewed from the direction B in FIG. As shown in FIG. 6, two nests 10 and a mold body 40 are provided.
, And a gate is provided therebetween as shown in FIG. Therefore, one molding of the molding machine 30 requires 2
Each light guide plate can be formed. by the way,
FIG. 7 is a sectional view taken along line AA of FIG. In the present embodiment, as described above, the material of the mold body 40 of the molding machine 30 and the material of the base material 13 of the insert 10 are formed to be the same. As described above, by selecting the same material as the base material 13 and the mold body 40, the linear expansion coefficients of the base material 13 and the mold body 40 match, and the design of the mold body 40 becomes easy. In addition, when a stainless steel material is selected, resin molding can be performed at a high temperature, so that the occurrence of overpacking and burrs of the resin can be reduced, and the deterioration of the quality of these molded products can be minimized. Become. Also, the base material 13 and the mold body 4
By selecting martensitic stainless steel or cemented carbide as the material of No. 0, it is possible to obtain a predetermined hardness and excellent corrosion resistance.

FIG. 2 (B) shows the surface of the base material 13.
As shown in FIG. 1, an electric Ni-P plating film 12 is formed by an electroforming method. The formation of the electric Ni-P plating film 12 is performed by, for example, a plating apparatus 30 shown in FIG. In FIG. 3, a plating apparatus 30 accommodates a processing solution 32 composed of a nickel sulfamate solution, nickel chloride, phosphorous acid, boric acid, or the like in a processing tank 31, and is connected to a positive electrode in the processing solution 32. The nickel plate 33 thus immersed and the base material 20 as a work connected to the negative electrode are immersed. And
The pH of the processing liquid 32 is 1 to 1.5, the liquid temperature is 50 ° C., and the current is 1
Electroforming is performed under the condition of 5 A / dm ² . Here, the plating film 12 formed by electric Ni-P plating has a Ni-P deposition rate about 10 times as high as that of electroless Ni-P plating, and the treatment liquid can be easily managed. According to the electric Ni-P plating, the content of P (phosphorus) can be 10% or more. Thus, P
With the content of 10% or more, as shown in FIG. 8, that is, a height of 100 μm having a top of 60 degrees.
It can be seen that when the ridge leaving process is performed with the tool 8 to a certain extent, the size of the burr is reduced as shown in FIG.

As described above, by setting the P content to 10% or more, the workability is improved without generating burrs or the like on the plating film 12 even by diamond cutting described later. Further, according to the above-described electric Ni-P plating, unlike the electroless Ni-P plating, the plating film 12 formed on the surface of the base material 13 can be easily reduced to about 1 mm,
The thickness of the plating film 12 corresponding to the depth of 0.3 mm, which is the deepest part of the V-groove 11 shown in FIG. 1, can be realized. On the other hand, when a plating film is formed by electroless Ni-P plating, management of the liquid concentration and temperature is required as described above, and the film thickness is usually about 0.1 mm or less. Therefore, the thickness of the nest 10 shown in FIG.
A minimum of 0.4 mm or more cannot be achieved. Also,
Since the time required for the electric Ni-P plating is shorter than that of the electroless Ni-P plating, the production is easily performed in a short time, and the yield is improved.

Next, as shown in FIG. 2C, the plating film 12 is subjected to secondary processing so that the outer shape becomes a predetermined shape.
The film thickness distribution is corrected. Thereby, the film thickness distribution becomes highly accurate. Subsequently, as shown in FIG. 2D, the plated film 12 that has been subjected to the secondary processing as described above is
4, V-grooves 11 are formed by direct cutting.
In this case, since the content of phosphorus in the plating film 12 is 10% or more, the plating film 12 is rich in brittleness, is easily processed, and the life of the diamond bite 14 is extended, and
Even a V-shaped groove 11 having a depth of 0.3 mm can be easily formed. In addition, the V-groove 1
Since 1 is cut, the dimensional accuracy of the V-groove 11 is improved, and the nest 10 with high accuracy is manufactured. In particular, since the V-groove 11 shown in FIG. 1 needs to be formed accurately in a depth range of 0.01 mm to 0.3 mm, dimensional accuracy is particularly required.
Since V has good workability, the V-groove 11 is accurately formed. Further, when the V-groove 11 is formed, the mirror surface formed on the slope of the V-groove 11 is also formed with high precision. Thus, the molding die insert 10 having the molding region corresponding to the V-groove of the light guide plate substrate formed of a transparent plate such as an acrylic resin is completed.

Finally, preferably, said nest 10
A high hardness treatment is applied to the plating film 12, which is the upper surface of the V-groove 11, and the like. This high hardness treatment is performed, for example, at 400 ° C. for 1 hour.
The plating film 1 is formed by a curing treatment by heating for a long time.
The hardness of the upper surface of No. 2 before the hardening process is about Hv500, while the hardness after the hardening process can be increased to, for example, about Hv1000. This reduces damage to the upper surface of the plating film 12 of the nest 10 when assembling the light guide plate substrate with the molding die of the nest 10, thereby contributing to a longer life and sufficiently withstanding a high injection pressure. be able to. Therefore, thermal deformation during molding is suppressed to a minimum, and the V-grooves are formed by accurately transferring the shape of the V-grooves 11 of the plating film 12 of the insert 10 to the light guide plate substrate as a molded product. Can be. Accordingly, a high-quality light guide plate substrate is manufactured. Since the conductive plate substrate formed here is used for a liquid crystal display having a so-called front light configuration, it is required to ensure high luminance, uniformity of luminance, and transparency by miniaturization. Such a light guide plate substrate requiring high precision can be easily and efficiently manufactured by using the mold using the nest 10 according to the present embodiment.

In addition, the above-described high hardness processing is performed, for example, in FIG.
As shown in FIG. 7, the high hardness film 15 is formed on the upper surface of the plating film 12. In FIG.
The high hardness film 15 is made of a material having a higher hardness than the base material 13 and the plating film 12 such as chromium, platinum, titanium, titanium nitride, and iridium.
For example, a thickness of 0.002 mm or less is formed on the surface of No. 2 by plating or a vacuum film forming method. This allows
Problems such as corrosion deterioration and low hardness of the base material 13 are overcome, and the nest 20 suitably used for the mold for forming the light guide plate substrate is manufactured.

In the above-described embodiment, the molding die for the light guide plate substrate for the back illumination of the liquid crystal display and the method of manufacturing the same have been described. It is apparent that the present invention can be applied to a molding die for various resin molded products including an optical element having the same. For example, the present invention can be applied to aspherical lenses, polygon mirrors, and the like as various precision mirror surface parts. it can.

[0030]

As described above, according to the present invention, it is possible to easily form a molding area for molding a molded part into a predetermined shape, and to obtain a resin molded part having high precision and excellent durability. And a method for producing the same.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a nest used for a mold according to an embodiment of the present invention.

FIG. 2 is a process chart sequentially showing a process for manufacturing the nest of FIG. 1;

FIG. 3 is a schematic diagram showing a configuration of an example of a plating apparatus for electric Ni-P plating in the manufacturing method of FIG. 2;

FIG. 4 is a schematic sectional view showing a modification of the nest of FIG. 1;

FIG. 5 is a schematic view showing a molding machine having a partial cross section using the nest of FIG. 1;

FIG. 6 is a view as seen from a direction B in FIG. 5;

FIG. 7 is a schematic view showing a cross-sectional view taken along the line AA of FIG. 6;

FIG. 8 is a schematic sectional view showing a configuration of an example of a conventional light guide plate substrate.

9 is a process chart sequentially showing an example of a method for manufacturing a mold for molding the light guide plate substrate of FIG.

FIG. 10 is a schematic diagram showing a configuration of an example of a plating apparatus for electroless Ni—P plating in the manufacturing method of FIG. 9;

FIG. 11 is a schematic perspective view showing an example of ridge-leaving processing of an electroless Ni—P plating film in the manufacturing method of FIG. 9;

FIG. 12 shows an electroless Ni-P in the mountain leaving process of FIG.
5 is a graph showing the relationship between the phosphorus content of a plating film and the size of burrs at the peak.

FIG. 13 is a process chart sequentially showing another example of a conventional method for manufacturing a light guide plate substrate molding die.

[Explanation of symbols]

10, 20 ... nesting, 11 ... V-groove, 13 ...
Base material, 12: plating film, 14: diamond bite, 15: high hardness film

Claims (8)

[Claims] 1. A molding die for a resin molded part, wherein a molding region for molding the resin molded part is formed by a nest, wherein the nest is formed on a base and a surface thereof by an electroforming method. A mold for molding a resin molded part, comprising: a plating part; and the plating part is provided with a molding region part for molding the molded part. 2. The molding die for a resin molded part according to claim 1, wherein the molding region is a groove and / or a mirror surface provided by cutting or polishing. 3. The method according to claim 1, wherein the base is made of a high-hardness base material made of martensitic stainless steel or cemented carbide, and the plating part is made of an electric Ni-P plating film. Mold for molding resin molded parts. 4. The molding die according to claim 2, wherein the surface of the groove and / or the mirror surface is subjected to a high hardness treatment. 5. A method for manufacturing a molding die for a resin molded component, wherein a molding region for molding the resin molded component is formed by nesting, wherein a plating portion is formed on a surface of a base of the nest by electroforming. Forming a molding region for molding the molded component in the plated portion. A method of manufacturing a molding die for a resin molded component, the method comprising: 6. The resin molded part according to claim 5, wherein the molding region is a groove and / or a mirror surface, and the molding region is formed by a cutting or polishing process. Method for manufacturing a molding die. 7. The method according to claim 5, wherein the base is made of a high-hardness base material made of martensitic stainless steel or a cemented carbide, and the plating part is made of an electric Ni—P plating film. A method for manufacturing a molding die for a resin molded part. 8. The method according to claim 5, wherein the surface of the molding region is subjected to a high hardness treatment.