JP2001260139A - Mold for molding, molding apparatus, method for molding optical element, and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold which has a simple construction but prevents generation of a stress during solidification and melt of a thermoplastic resin by a cavity surface, a molding apparatus, a method for molding an optical element and an optical element having no distortion due to such a stress. SOLUTION: A mold for molding has a cavity surface contacting a thermoplastic resin, at least a part of the cavity surface being subjected to a release treatment. The molding apparatus and the method for molding the optical element uses the mold and the optical element is molded by using the them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die, a molding apparatus or an optical element molding method for producing an optical element by molding a thermoplastic resin, or an optical element molded by these.

[0002]

2. Description of the Related Art Conventionally, it has been known that a thermoplastic resin is confined in a cavity surface formed in a forming die such as a mold to form an optical element such as a lens or a mirror. The optical element is formed by injecting a thermoplastic resin in a liquid state into the cavity surface and gradually cooling it, or by molding a thermoplastic resin which has been molded and solidified in a desired shape to some extent elsewhere. Placed in the plane, it may be molded by slow cooling after heating and melting, but in any case, the thermoplastic resin is in a molten state at least once in the molding die, then Solidified.

It is known that a thermoplastic resin in a molten state shrinks by 8 to 14% in volume when solidified. Therefore, in the process of cooling and solidifying the thermoplastic resin, the thermoplastic resin moves with respect to the cavity surface,
At this time, a stress is generated in a direction in which the surface of the thermoplastic resin is pulled toward the cavity surface. Therefore, as shown in FIG. 8, the thermoplastic resin moves with shrinkage inside, but hardly moves on its surface. Also, in the process of applying a holding pressure following injection filling of the molten resin into the cavity or at the moment when the holding pressure is removed, the thermoplastic resin moves with respect to the cavity surface. A stress is generated in the direction in which the cavity surface is pulled. Therefore, also in this case, as shown in FIG. 8, the thermoplastic resin moves in accordance with the application and removal of the holding pressure, but hardly moves on the surface. For this reason, there is a problem in that distortion occurs in the solidified and molded optical element, which adversely affects the optical characteristics.

[0004] To solve this problem, Japanese Patent Laid-Open No. 5-33 is disclosed.
No. 7975 discloses that when a thermoplastic resin is cooled and solidified, a stress is applied to the thermoplastic resin itself, and a shear stress is applied between the thermoplastic resin surface and the cavity surface, so that the thermoplastic resin is cooled by the cavity surface. A technique has been proposed in which a thermoplastic resin can be smoothly moved even on its surface with shrinkage without generating stress on the resin, and distortion is avoided to improve optical characteristics of an optical element. .

[0005]

However, in the above technique, the mechanism for applying stress to the thermoplastic resin itself becomes complicated, the device becomes large, and the application of stress to the thermoplastic resin itself causes distortion. There is a problem that it becomes a factor of deteriorating optical characteristics. In addition, the problem of distortion of the optical element also occurs when the solidified thermoplastic resin is fixed in the cavity surface, heated and melted, as shown in FIG.

The present invention has a simple structure, a molding die, a molding apparatus and an optical element molding method for preventing the generation of stress when the thermoplastic resin is solidified and melted by the cavity surface, and there is no distortion due to such stress. It is an object to provide an optical element.

[0007]

In order to achieve the above object, the invention according to claim 1 is a molding die for molding a thermoplastic resin to produce an optical element having at least one smooth surface, A molding die having a cavity surface in contact with a thermoplastic resin, characterized in that the cavity surface has a treated surface on which a release treatment has been performed on the thermoplastic resin.

According to a second aspect of the present invention, in the molding die of the first aspect, the processing surface is formed by applying a release agent to the cavity surface.

The invention described in claim 3 is the first or second invention.
In the molding die described above, the processing surface is formed by plating at least a portion of the cavity surface corresponding to the smooth surface.

According to a fourth aspect of the present invention, there is provided a molding die for producing an optical element having a smooth surface on at least one side by molding a thermoplastic resin, the molding die having a cavity surface in contact with the thermoplastic resin. It is characterized in that at least a part of the cavity surface is provided with a molding die having a treated surface obtained by subjecting a thermoplastic resin to a release treatment.

According to a fifth aspect of the present invention, in the molding apparatus of the fourth aspect, the processing surface is formed by applying a release agent to the cavity surface.

The invention according to claim 6 is the first or second invention.
In the above described molding apparatus, the processing surface is formed by plating the cavity surface.

The invention according to claim 7 is the invention according to claims 4 to 6.
In the molding apparatus according to any one of the above, the solidified thermoplastic resin in the molding die is heated and melted, and then solidified again.

The invention according to claim 8 is the first to third aspects of the present invention.
The molding die according to any one of claims 1 to 7, or a molding die according to any one of claims 4 to 7.
An optical element molding method for molding an optical element using the molding apparatus according to any one of the above.

The ninth aspect of the present invention provides the first to third aspects.
The molding die according to any one of claims 1 to 7, or a molding die according to any one of claims 4 to 7.
An optical element molded by using the molding apparatus according to any one of the above or the optical element molding method according to claim 6.

[0016]

FIG. 1 shows a molding apparatus to which the present invention is applied. The molding apparatus 1 includes a mold 2 as a molding die, a heat insulating layer 3 disposed to surround the mold 2, a mold plate 4 disposed to surround the heat insulating layer 3, and a mold. A pair of plates 5 opposed to each other with the plate 4 interposed therebetween, an arm 6 for moving the plates 5 closer to and away from each other, a heater 7 as a heating means and a cooling means as the heating means disposed at the outer edge of the mold 2. And a cooling hole 8. The mold 2 is made of an iron alloy and has a heat insulating layer 3.
Is made of bakelite, but may be made of glass fiber, and the template 4 is made of an iron alloy.

The mold 2 is composed of an upper mold 2a and a lower mold 2b.
Are formed, and the cavity surface 9 is formed by the concave portions 9a and 9b.
Is formed. Thermal insulation layer 3
Is an upper heat-insulating layer 3a on the upper mold 2a side facing each other;
The mold plate 4 includes a lower heat insulating layer 3b on the lower mold 2b side, and the upper mold plate 4a and the lower mold 2 on the upper mold 2a side facing each other.
b, a lower mold plate 4b, and the plate 5 comprises an upper plate 5a on the upper mold 2a side and a lower mold 2b
And the lower plate 5b of the upper mold 2
An upper arm 6a on the a side and a lower arm 6b on the lower mold 2b side.

The upper mold 2a, the upper heat insulating layer 3a, the upper mold plate 4a,
The upper plate 5a and the upper arm 6a are integrated, and the lower mold 2b, the lower heat insulating layer 3b, the lower mold plate 4b, and the lower plate 5b
The lower arm 6b is integral with the lower arm 6b. When one or both of the arm 6a and the arm 6b are displaced in a direction away from each other by a drive source (not shown), the upper mold 2a and the lower mold 2b are separated, the cavity 10 is released, and the cavity surface is released. 9 is exposed.

A plurality of heaters 7 and cooling holes 8 are alternately arranged in the upper mold 2a and the lower mold 2b, respectively. The heater 7 is connected to a heating source (not shown), and is heated by the heating source to increase the temperature, thereby heating and increasing the temperature of the mold 2. The cooling hole 8 is connected to a cooling device (not shown), and cools the mold 2 by introducing a cooling catalyst from the cooling device. Since the mold 2 is surrounded by the heat insulating layer 3, the temperature in the mold 2 is:
The temperature of the mold 2 and the rate of temperature rise and cooling thereof are controlled satisfactorily by controlling the heating source and the cooling device without being affected by the components other than the heater 7 and the cooling holes 8. The heater 7 and the cooling hole 8 constitute a temperature adjusting means. However, the temperature adjusting means does not necessarily need to be provided on the mold 2 and may be provided on the mold plate 4. When the temperature control means is provided on the template 4, the heat insulating layer 3 is
And between them.

The entire surface of the cavity surface 9 has been subjected to mold release treatment by plating with fluorine-containing organic plating, in this embodiment, triazine thiol, and the entire surface of the cavity surface 9 has been treated. . This mold release treatment is for improving the mold releasability between the thermoplastic resin (hereinafter referred to as “resin”) to be molded and the cavity surface 9. The processing surface is formed on at least a portion corresponding to a smooth surface that is a surface for determining optical characteristics, that is, a lens surface or a mirror surface (hereinafter, referred to as a “mirror surface”) of an optical element obtained by molding a resin. Things. Therefore,
It is not always necessary to form the processing surface on the entire surface of the cavity surface 9 as in this embodiment. The release treatment for forming the treated surface is not limited to fluorine-containing organic plating,
This may be performed by plating titanium nitride or nickel impregnated with Teflon (registered trademark) particles, for example, Nif Grip (trade name), or by applying a lubricant such as paintable AFL (trade name). . However, when it is difficult to ensure the smoothness and cleanliness of the mirror surface as in the treatment other than the organic plating of triazine thiol, the process is performed only on the cavity surface other than the mirror surface.

The molding device 1 is for molding a resin.
As resin, polycarbonate resin and acrylic resin,
Cycloolefin resin such as Zeonex (trade name)
Can be used. Forming apparatus 1 in the present embodiment
Is for producing an optical element by an optical element molding method called a so-called remelt molding method. In the remelt molding method, a resin, which has been solidified in a shape close to a shape to obtain desired optical characteristics in advance, is sealed in a molding die, heated and melted, then cooled and solidified again, so that the accuracy of the optical characteristics is improved. This is to obtain an optical element having a high level. The molding device 1 is for sealing the resin once solidified by another device into the cavity 10 and melting and solidifying the resin. As shown in FIG. 6, the resin in the molten state is filled in the cavity 10 and temporarily melted. It may be solidified and then melted and solidified again in the cavity. Further, as shown in FIG. 6, an apparatus for obtaining a desired optical element only by filling and solidifying a molten resin in the cavity 10 may be used. The molding apparatus shown in FIG. 6 is different from the molding apparatus 1 described above in that a resin flow path 13 is provided in the mold 2 and a resin injection means 14 connected to the resin flow path 13 and injecting and filling the resin into the cavity 10 is provided. It is different, and has the same configuration as the molding apparatus 1 in other points.

Since the molding apparatus 1 of this embodiment has the above-described configuration, the manufacture of the optical element is performed as follows.
A resin solidified in a shape close to a shape for obtaining desired optical characteristics in another molding apparatus in advance is placed at a predetermined position in the cavity 10 thus opened. As shown in FIG.
The mold 6 is heated by the heater 7 in a state where the resin is confined in the cavity 10 by driving the arm 6 and sealed at a high pressure. The resin melts as the temperature of the mold 2 rises,
Since the resin expands upon melting, the resin is not
To move against. At this time, in the present embodiment, since the mold release process has been performed on the cavity surface 9, as shown in FIG. 3, which is an enlarged view of the portion indicated by reference numeral 11 in FIG. Is not generated, the resin moves smoothly inside and on the surface as the resin expands, and no shear distortion is generated in the resin, so that no optical distortion is generated in the optical element. On the other hand, when the mold release treatment is not performed, as shown in FIG. 7, a stress is generated in a direction in which the resin surface is pulled toward the cavity surface 9, and the resin moves inside the cavity with expansion. Nevertheless, movement is hindered on the surface, so that shear strain is generated in the resin and internal strain is generated, so that optical distortion occurs in the optical element.

As the resin expands, the inside of the cavity 10 becomes high in pressure, but the cavity 6 is sealed by the arm 6, and the resin is pressed against the cavity surface 9 by its own pressure to form a predetermined mirror surface. The shaped cavity surface 9 is transferred to the resin surface, and the surface of the resin becomes a predetermined mirror surface.

When the mirror surface is formed on the resin surface, the heater 7
Then, as shown in FIG. 4, a cooling catalyst is supplied to the cooling holes 8 to gradually cool the resin together with the mold 2. Cooling is performed so that the temperature of the entire resin is reduced in a uniform state. As the temperature decreases, the resin starts to solidify, but the resin shrinks during the solidification, so that the resin moves with respect to the cavity surface 9. At this time, in this embodiment, the cavity surface 9 is used.
As shown in FIG. 5 in which the portion indicated by reference numeral 12 in FIG. 4 is enlarged, no stress is generated in the direction in which the resin surface is pulled to the cavity surface 9 and the resin is However, even on the surface, the resin moves smoothly with shrinkage, and no shear strain occurs in the resin, so that no optical strain occurs in the optical element.
On the other hand, when the mold release treatment is not performed, as shown in FIG. 8, a stress is generated in a direction in which the resin surface is pulled to the cavity surface 9, and the resin moves inside with shrinkage. Nevertheless, the movement is hindered on the surface, so that shear strain occurs in the resin and internal strain occurs, so that optical distortion occurs in the optical element.

When the solidification is completed, the arm 6 is driven to release the cavity 10 and the molded optical element is taken out. This optical element is not affected by the stress due to the cavity surface 9 when heating and cooling the resin, and has very high precision optical characteristics.

The production of an optical element by the molding apparatus shown in FIG. 6 is performed as follows. The resin heated and melted in advance is injected and filled into the closed cavity 10 by the resin injection means 14. As indicated by reference numeral 15, a high holding pressure is applied to the resin by the resin injection means 14, and a cooling catalyst is supplied to the cooling holes 8 to gradually cool the resin together with the mold 2. When the holding pressure 15 is applied, the resin
However, since the cavity surface 9 has been subjected to the mold release treatment, optical distortion does not occur in the resin as described above. Similarly, at the time of slow cooling, optical distortion does not occur in the resin or the optical element obtained by curing the resin. Further, similarly, when the holding pressure 15 is released after the resin is cured, no optical distortion occurs in the optical element. In the case where there is a step of melting and solidifying again, the holding pressure 15 is applied and released again in this step, but in this case, the optical element is similarly released by the mold release treatment performed on the cavity surface 9. There is no optical distortion. If there is no step of melting and solidifying again, the heater 7 is not an essential component.

Although the embodiments of the present invention have been described above, the cooling means is not always necessary, and the cooling can be performed by radiating heat. The melting and solidification of the resin may be performed a plurality of times. In this case, even if the resin is repeatedly expanded and contracted, no distortion occurs, which is particularly suitable for improving the optical characteristics of the optical element with high accuracy.

[0028]

According to the first aspect of the present invention, there is provided a molding die for producing an optical element having a smooth surface on at least one side by molding a thermoplastic resin. In a molding die having a cavity surface in contact with a resin, since the cavity surface has a treated surface subjected to a release treatment for the thermoplastic resin, the solidification and melting of the thermoplastic resin by the cavity surface can be performed with a simple configuration. In this case, it is possible to provide a molding die capable of preventing generation of stress at the time of manufacture and capable of manufacturing an optical element having high-precision optical characteristics.

According to a second aspect of the present invention, in the molding die of the first aspect, since the treated surface is formed by applying a release agent to the cavity surface, the release agent is applied. Because the processing surface can be formed only with
With a simple configuration such as applying a release agent to a conventional forming mold,
It is possible to provide a molding die that can prevent the generation of stress when the thermoplastic resin is solidified and melted by the cavity surface and can manufacture an optical element having high-precision optical characteristics.

The third aspect of the present invention is the first or second aspect.
In the molding die described above, since the processing surface is formed by plating at least a portion of the cavity surface corresponding to the smooth surface, the state of the processing surface can be kept good over time. A molding die with improved maintainability that can prevent the occurrence of stress during solidification and melting of the thermoplastic resin due to the cavity surface and can produce an optical element having high-precision optical characteristics. Can be provided.

According to a fourth aspect of the present invention, there is provided a molding die for producing an optical element having a smooth surface on at least one side by molding a thermoplastic resin, wherein the molding die has a cavity surface in contact with the thermoplastic resin. Since at least a part of the cavity surface is a molding device having a molding die having a treated surface subjected to a mold release treatment for the thermoplastic resin, the solidification and melting of the thermoplastic resin by the cavity surface can be performed with a simple configuration. In this case, it is possible to provide a molding apparatus capable of preventing generation of stress at the time of manufacture and capable of manufacturing an optical element having high-precision optical characteristics.

According to a fifth aspect of the present invention, in the molding apparatus of the fourth aspect, since the processing surface is formed by applying a release agent to the cavity surface, only the release agent is applied. Can form a treated surface,
With a simple configuration such as applying a release agent to a conventional forming mold,
It is possible to provide a molding apparatus capable of preventing generation of stress at the time of solidification and melting of a thermoplastic resin due to a cavity surface, and capable of manufacturing an optical element having high-precision optical characteristics.

The invention according to claim 6 is the first or second invention.
In the molding apparatus described above, since the processing surface is formed by plating the cavity surface, the state of the processing surface can be favorably maintained over time, and the solidification of the thermoplastic resin by the cavity surface and It is possible to provide a molding apparatus with improved maintainability, which can prevent generation of stress at the time of melting and can manufacture an optical element having high-precision optical characteristics.

The invention according to claim 7 is the invention according to claims 4 to 6
In the molding apparatus according to any one of the above, since the solidified thermoplastic resin in the molding die is heated and melted and then solidified again, the optical system has a simple configuration and further high-precision optical characteristics. A molding apparatus capable of manufacturing an element can be provided.

The invention described in claim 8 is the first to third inventions.
The molding die according to any one of claims 1 to 7, or a molding die according to any one of claims 4 to 7.
Since the optical element molding method for molding an optical element using the molding apparatus according to any one of the above, an inexpensive and high-precision optical element can be provided with a relatively simple structure.

The ninth aspect of the present invention provides the first to third aspects.
The molding die according to any one of claims 1 to 7, or a molding die according to any one of claims 4 to 7.
Since the optical element is molded by using the molding apparatus according to any one of the above or the optical element molding method according to claim 6, it is possible to relatively easily provide an inexpensive and highly accurate optical element. .

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a molding apparatus to which the present invention is applied.

FIG. 2 is a schematic enlarged view of the molding die shown in FIG.

FIG. 3 is a partially enlarged view of the molding die shown in FIG. 2;

FIG. 4 is a schematic enlarged view of the molding die shown in FIG.

5 is a schematic enlarged view of the molding die shown in FIG.

FIG. 6 is a view showing a main part of another example of a molding apparatus to which the present invention is applied.

FIG. 7 is a partially enlarged view of a conventional molding die corresponding to FIG.

FIG. 8 is a partially enlarged view of a conventional molding die corresponding to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Forming apparatus 2 Mold 9 Cavity surface 10 Cavity

Claims (9)

[Claims] 1. A molding die for producing an optical element having a smooth surface on at least one side by molding a thermoplastic resin, wherein the molding surface has a cavity surface in contact with the thermoplastic resin. A mold having a treated surface obtained by subjecting a thermoplastic resin to a release treatment. 2. The molding die according to claim 1, wherein said treated surface is formed by applying a release agent to said cavity surface. 3. The molding die according to claim 1, wherein the processing surface is formed by plating at least a portion of the cavity surface corresponding to the smooth surface. Mold for molding. 4. A molding die for producing an optical element having a smooth surface on at least one side by molding a thermoplastic resin, the mold having a cavity surface in contact with the thermoplastic resin, and at least a part of the cavity surface. A molding die having a treated surface on which a release treatment has been performed on a thermoplastic resin. 5. The molding apparatus according to claim 4, wherein the processing surface is formed by applying a release agent to the cavity surface. 6. The molding apparatus according to claim 1, wherein the processing surface is formed by plating the cavity surface. 7. The molding apparatus according to claim 4, wherein the solidified thermoplastic resin in the molding die is heated and melted, and then solidified again. apparatus. 8. An optical element is molded by using the molding die according to any one of claims 1 to 3 or the molding apparatus according to any one of claims 4 to 7. Optical element molding method. 9. A molding die according to any one of claims 1 to 3, a molding apparatus according to any one of claims 4 to 7, or an optical element molding method according to claim 6. An optical element characterized by being formed by molding.