JP2022147478A - Method for manufacturing plastic element and apparatus for manufacturing plastic element - Google Patents

Abstract

To provide a method for manufacturing a plastic element capable of improving a transfer accuracy of the plastic element with a simple configuration.SOLUTION: There is provided a method for manufacturing a plastic element, in which a plastic element is molded by heating and curing a thermosetting resin having a predetermined pattern transferred thereon. The method includes the steps of: fixing a pair of molds by sandwiching a thermosetting resin between the pair of molds; and heating the pair of molds to cure the thermosetting resin. At least one of the pair of molds includes: a transfer unit that transfers the pattern in contact with the thermosetting resin; and an expansion unit that expands in a compression direction in which the transfer unit compresses the thermosetting resin by heating. An expansion amount of the expansion unit is greater than or equal to an amount of curing shrinkage of the thermosetting resin.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a plastic element and a manufacturing apparatus for a plastic element.

In recent years, in order to improve the uniformity of illuminance in three-dimensional sensing using Tof (Time of Flight) and improve the accuracy of distance measurement, optical elements with micro/nano-order fine structures, such as microlens arrays and diffractive optical elements, have been developed. is used.

As a method for manufacturing such an optical element, a liquid thermosetting resin is sandwiched between a flat plate-shaped upper mold and a lower mold in which a desired inverted shape of the optical surface is formed in advance, and heated to obtain an inverted shape. is transferred to a resin and the resin is cured.

In addition, a thermosetting resin that is liquid at room temperature undergoes volumetric shrinkage in the course of curing due to a crosslinking reaction caused by heating. In order to solve such a problem, a system is known in which pressure is applied by detecting the generation of negative pressure due to cure shrinkage at the gelation point where the viscosity of the thermosetting resin increases (for example, Patent Document 1).

However, the conventional technology requires a highly accurate sensor and a complicated control mechanism for detecting the gelation point and feeding it back. In addition, as the heating rate is increased in order to improve productivity, the control becomes more difficult, and there is a problem that the transfer accuracy of the plastic element is lowered.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a plastic element that can improve the transfer accuracy of the plastic element with a simple configuration.

One aspect of the present invention is a method for manufacturing a plastic element, in which a thermosetting resin to which a predetermined pattern has been transferred is cured by heating to form a plastic element, wherein the thermosetting resin is sandwiched between a pair of molds. and a step of heating the pair of molds to cure the thermosetting resin, wherein at least one of the pair of molds is in contact with the thermosetting resin. and an expanding portion that expands in a compression direction in which the transfer portion compresses the thermosetting resin by heating, and the amount of expansion of the expanding portion is equal to the amount of expansion of the thermosetting resin. is greater than or equal to the amount of curing shrinkage.

According to one aspect of the present invention, it is possible to improve the transfer accuracy of a plastic element with a simple configuration.

The schematic diagram which shows the manufacturing apparatus of a plastic element. 4 is a flow chart showing a method of manufacturing a plastic element. 4 is a flow chart showing a method of manufacturing a plastic element. 4 is a flow chart showing a method of manufacturing a plastic element. 4 is a flow chart showing a method of manufacturing a plastic element. FIG. 2 is a schematic diagram showing the manufacturing apparatus (manufacturing process) of the first embodiment; Schematic diagrams showing the manufacturing process of the first embodiment. Schematic diagrams showing the manufacturing process of the first embodiment. Schematic diagrams showing the manufacturing process of the first embodiment. Schematic diagrams showing the manufacturing process of the first embodiment. FIG. 4 is a diagram showing the relationship between the manufacturing process of a plastic element and pressure due to thermal expansion; It is an image showing the transfer surface of the mold, (a) is a laser microscope image, (b) is a three-dimensional display image of (a). It is an image which shows the lens surface of the plastic element of embodiment, (a) is a laser microscope image, (b) is a three-dimensional display image of (a). It is an image which shows the lens surface of the conventional plastic element, (a) is a laser microscope image, (b) is a three-dimensional display image of (a). The schematic diagram which shows the manufacturing apparatus (manufacturing process) of 2nd Embodiment. The schematic diagram which shows the manufacturing process of 2nd Embodiment. The schematic diagram which shows the manufacturing process of 2nd Embodiment. The schematic diagram which shows the manufacturing process of 2nd Embodiment. The schematic diagram which shows the manufacturing process of 2nd Embodiment. The schematic diagram which shows the manufacturing process of 2nd Embodiment. The schematic diagram which shows the manufacturing apparatus of 3rd Embodiment. The figure which shows the state before heating of the upper mold which comprises the manufacturing apparatus of 3rd Embodiment. The figure which shows the state at the time of heating of the upper mold which comprises the manufacturing apparatus of 3rd Embodiment. The schematic diagram which shows the manufacturing process of 3rd Embodiment. The schematic diagram which shows the manufacturing process of 3rd Embodiment. FIG. 10 is a diagram showing a plastic element obtained in the manufacturing process of the third embodiment; The schematic diagram which shows the manufacturing apparatus of 4th Embodiment. The schematic diagram which shows the manufacturing process of 4th Embodiment. The schematic diagram which shows the manufacturing process of 4th Embodiment. The schematic diagram which shows the manufacturing process of 4th Embodiment. The schematic diagram which shows the manufacturing process of 4th Embodiment. The schematic diagram which shows the manufacturing process of 4th Embodiment. The figure which shows an example of the lower side mold which comprises the manufacturing apparatus of 4th Embodiment. The figure which shows an example of the lower side mold which comprises the manufacturing apparatus of 4th Embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

<Method for manufacturing plastic element>
In the method of manufacturing a plastic element according to the present embodiment, a thermosetting resin having a predetermined pattern transferred thereon is cured by heating to form a plastic element.

The method for producing a plastic element of the present embodiment comprises the steps of fixing a pair of molds by sandwiching a thermosetting resin between the pair of molds, and heating the pair of molds to heat the liquid composition according to the present embodiment. and a step of curing the curable resin.

At least one of the pair of molds has a transfer portion that transfers the pattern in contact with the thermosetting resin, and an expansion portion that expands in a compression direction in which the transfer portion compresses the thermosetting resin due to heating. is greater than or equal to the curing shrinkage of the thermosetting resin.

Specifically, the method for manufacturing a plastic element of this embodiment is realized by the apparatus shown in FIG. FIG. 1 is a schematic diagram showing an apparatus for manufacturing a plastic element.

A plastic element manufacturing apparatus 100 shown in FIG. , and a temperature control section 40 formed in the lower die plate 20 and having a heat transfer section 41 , a heating section 42 and a cooling section 43 .

The plastic element manufacturing apparatus 100 further has a control section (not shown), and the drive section and the temperature control sections 30 and 40 are controlled by this control section. The control unit has a central processing unit (CPU) and a memory, and is connected to the driving unit and the temperature control units 30 and 40 by wire or wirelessly so as to be communicable.

An upper mold 50 is formed on the upper die plate 10 with a temperature control section 30 interposed therebetween. The upper mold 50 has an expansion portion 51 that thermally expands by heating and a transfer portion 52 . In the first embodiment, the transfer portion 52 constitutes the transfer surface of the upper mold 50, and the transfer portion 52 is formed with a predetermined pattern shape to be transferred to the plastic element. In the upper mold 50, an expansion portion 51 and a transfer portion 52 are integrally formed.

A lower mold 60 is formed on the lower die plate 20 with a temperature control section 40 interposed therebetween. The lower mold 60 has an expansion portion 61 that thermally expands by heating and a transfer portion 62 . In the first embodiment, the transfer portion 62 constitutes the transfer surface of the lower mold 60 and has a predetermined mirror surface shape to be transferred to the plastic element. In the lower mold 60, an expansion portion 61 and a transfer portion 62 are integrally formed.

In this specification, the upper mold 50 and the lower mold 60 are examples of the pair of molds of this embodiment, and the upper mold 50 is an example of at least one of the pair of molds of this embodiment.

Note that the transfer portion 62 may have a predetermined pattern shape to be transferred to the plastic element, like the transfer portion 52 of the upper mold 50 . Further, instead of the transfer portion 52, the transfer portion 62 may have a predetermined pattern shape to be transferred to the plastic element.

A thermosetting resin 90 is placed between the upper mold 50 and the lower mold 60 . In this embodiment, the upper mold 50 moves toward the lower mold 60 to which the upper mold 50 is fixed in accordance with the operation of the driving unit, and the transfer unit 52 contacts the thermosetting resin 90, so that the shape of the thermosetting resin 90 changes. transform. Further, the temperature of the upper and lower molds 50, 60 is controlled by the temperature of the temperature control parts 30, 40, and the thermosetting resin 90 is cured by heating and cooled.

In this specification, a thermosetting resin is a synthetic resin having thermosetting properties, which is insoluble in a solvent after curing and does not soften even when reheated. Thermosetting resins are not particularly limited, and examples thereof include epoxy resins, urethane resins, acrylic resins, urea resins, melamine resins, phenol resins, and resins.

The expansion portion 51 of the upper mold 50 is made of a high thermal expansion member. As the high thermal expansion member, a material having a coefficient of linear expansion of 10×10 ⁻⁶ /° C. or more and 50×10 ⁻⁶ /° C. or less is preferable, and more preferably 15×10 ⁻⁶ /° C. or more and 45×10 ⁻⁶ /° C. or less. more preferably 20×10 ⁻⁶ /° C. or more and 35×10 ⁻⁶ /° C. or less. As such a high thermal expansion member, for example, aluminum (linear expansion coefficient: 27×10 ⁻⁶ /° C.) can be used.

The thickness of the upper mold 50 is arbitrary, but when the expansion portion 51 of the upper mold 50 is made of a high thermal expansion member, it is preferable to set it to, for example, 20 mm or more and 60 mm or less in consideration of heat conduction. It is preferably 30 mm or more and 50 mm or less, and still more preferably 35 mm or more and 45 mm or less.

The expansion portion 61 of the lower mold 60 is made of a low thermal expansion member. As the low thermal expansion member, a material having a coefficient of linear expansion of less than 10×10 ⁻⁶ /° C. is preferable, more preferably a material having a coefficient of linear expansion of 8×10 ⁻⁶ /° C. or less, and further preferably a material having a linear expansion coefficient of 5×10 ⁻⁶ /° C. or less. is. The lower limit of the coefficient of linear expansion of the low thermal expansion member is not limited, and is usually 0.1×10 ^-6 /°C. As such a low thermal expansion member, for example, silicon (linear expansion coefficient: 3.9×10 ⁻⁶ /° C.) can be used.

In this embodiment, the high thermal expansion member is used on the upper side and the low thermal expansion member is used on the lower side. , both upper and lower sides may be high thermal expansion members. As a result, it is possible to establish a working mechanism in which the high thermal expansion member thermally expands in accordance with the temperature of the temperature control sections 30 and 40 and a compressive stress is applied in the transfer direction.

Here, a procedure of steps for executing the method for manufacturing a plastic element according to the present embodiment will be described. 2-5 are flow charts showing a method of manufacturing a plastic element. 6 to 10 show the manufacturing process of the first embodiment. FIG. 11 shows the relationship between the manufacturing process of the plastic element and the pressure due to thermal expansion.

The method for manufacturing a plastic element according to the present embodiment includes a resin coating process, a mold closing process, a heating process, a cooling process, and a mold opening process (steps S1 to S5 in FIG. 2).

In the resin coating process (FIG. 2, step S1), the upper die plate 10 and the lower die plate 20 stand by at a separated position (FIG. 3, step S11). At this time, the transfer portion 52 of the upper mold 50 is on standby at a position away from the thermosetting resin 90 (FIG. 6). The temperature control units 30 and 40 are kept preheated to a constant temperature ( FIG. 4 , step S21). A liquid thermosetting resin 90 is applied to the lower mold 60 (FIG. 5, step S31).

In the mold closing step (FIG. 2, step S2), the upper die plate 10 is lowered and stopped at a distance D1 from the standby position (FIG. 3, steps S12 and S13). Thereby, the upper mold 50 is fixed with respect to the lower mold 60 . Further, the transfer portion 52 of the upper mold 50 also stops at a position lowered by a distance D1 from the standby position, and is in contact with the thermosetting resin 90 (FIG. 7).

At this time, the pressure behavior takes a value close to zero (left side of the solid line in FIG. 11). Although a slight positive pressure is generated by contact with the resin material, it can be regarded as almost zero because it is a liquid.

The mold closing step ( FIG. 2 , step S2) is an example of a step of fixing a pair of molds by sandwiching a thermosetting resin between them in this embodiment.

In the heating step (FIG. 2, step S3), heating is started by the temperature control units 30 and 40 (FIG. 4, step S22). Thereby, the upper mold 50 and the lower mold 60 are also heated. At this time, the upper mold 50 made of a high thermal expansion member thermally expands.

Therefore, although the drive section (upper die plate 10) is not moving, the transfer section 52 of the upper mold 50 is further lowered by the distance D2 (FIG. 8). As a result, even if the thermosetting resin 90 cures and shrinks, a compressive stress is applied in the transfer direction (points (A) and (B) in FIG. 11).

Furthermore, when the heating is maintained by the temperature control units 30 and 40 (FIG. 4, step S23), the heating temperature by the temperature control units 30 and 40 becomes constant, and the amount of thermal expansion settles to a constant value, so the pressure becomes constant. (Point (C) in FIG. 11). At this time, the lowering of the transfer portion 52 of the upper mold 50 is stopped (FIG. 8).

Further, the thermosetting resin 90 becomes the gelled thermosetting resin 91 and undergoes volumetric shrinkage (curing shrinkage), but due to the compressive stress from the expanded upper mold 50, it remains in close contact with the transfer portion 52 (Fig. 8).

On the other hand, in the case of a normal molding method (upper mold 150 and lower mold 160) that does not use a high thermal expansion member, when heating is started and the thermosetting resin 190 gels, volume shrinkage (hardening shrinkage) occurs (FIG. 11). (E) point).

At this time, as long as the transfer surface of the upper mold 150 and the gelled thermosetting resin 191 are in close contact with each other, a tensile stress acts and a negative pressure is generated. Further, when the shrinkage progresses and becomes unbearable, the gelled thermosetting resin 191 is peeled off from the transfer surface of the upper mold 150 and the pressure becomes zero (FIG. 11(F)).

In addition, in the case of the prior art (Patent Document 1), complicated feedback control is performed by detecting the negative pressure in this process and controlling the drive unit to finely adjust the die plate position. However, the transferability can be improved only by heating without performing such a complicated configuration and control.

In this specification, the heating step is an example of a step of heating the pair of molds in the present embodiment to harden the thermosetting resin.

In the cooling step (FIG. 2, step S4), cooling by the temperature control units 30 and 40 is started (FIG. 4, step S24). As a result, the expanded upper mold 50 contracts and returns to its original state. Along with this, the transfer portion 52 of the upper mold 50 rises and returns to the original position (the position at the distance D1 from the standby position). After that, the cooling by the temperature control units 30 and 40 ends ( FIG. 4 , step S25).

Since the hardened and solidified thermosetting resin (molded article) 92 also thermally shrinks when cooled, a force acts in the direction in which the upper mold 50 and the molded article are separated from each other (FIG. 9). As a result, the pressure approaches zero (point (D) in FIG. 11). At this time, since the molded product 92 is solidified sufficiently, even if it is peeled off from the mold, the transfer accuracy is maintained as a plastic element.

In the mold opening step (FIG. 2, step S5), the upper die plate 10 is lifted and put on standby, and the transfer portion 52 of the upper mold 50 is lifted to return to the standby state (FIG. 3, steps S14 and S15). Thereby, the molded product 92 can be taken out as a plastic element (FIG. 5, step S32).

If steps S1 to S5 are to be repeated after the mold opening step (step S5 in FIG. 2), the process returns to the resin coating step (step S1 in FIG. 2) and steps S1 to S5 are executed. If steps S1 to S5 are not to be repeated, the steps are terminated.

When steps S1 to S5 are repeated (FIG. 2, step S6), the upper die plate 10 stands by while being raised (FIG. 3, steps S15 and 16). At this time, the temperature control sections 30 and 40 are kept preheated to a constant temperature in preparation for the next molding (steps S26 and S27 in FIG. 4), and the liquid thermosetting liquid is applied to the lower mold 60 again. Resin 90 is applied (FIG. 5, step S33).

In the case of a molding method that does not use a high thermal expansion member, as shown in FIG. 11, in the heating process, the thermosetting resin is peeled off from the transfer surface and the pressure becomes zero. Since the thermosetting resin is peeled off in an uncured state, the molded product may suffer from sink marks and poor shape accuracy (FIGS. 12 and 14).

On the other hand, in the present embodiment, by using a high thermal expansion member, even if the thermosetting resin cures and shrinks in the heating process, the thermal expansion of the upper mold 50 (expansion portion 51) compresses in the transfer direction. stress is applied. Therefore, it is possible to suppress the sink mark of the molded product 92 and improve the shape accuracy (FIGS. 12 and 13).

If the amount of movement of the transfer portion 52 due to the thermal expansion of the upper mold 50 (distance D2 in FIG. 11), that is, the amount of expansion of the expansion portion 51 is equal to or greater than the curing shrinkage amount of the resin, the resin will not separate from the transfer surface. do not have. In this case, the pattern of the transfer portion 52 can be reliably transferred onto the thermosetting resin 90 .

For example, the preheating temperature is 100° C., the heating temperature is 150° C., the curing shrinkage of the thermosetting resin is 5%, and the thickness of the molded product is 1 mm. Further, as described above, if the material of the upper mold 50 is aluminum (linear expansion coefficient: 27×10 ⁻⁶ /° C.) and its thickness is 40 mm, the amount of thermal expansion is greater than the amount of curing shrinkage as follows. A relationship (amount of thermal expansion≧amount of curing shrinkage) is established, and the pattern shape of the transfer portion 52 can be reliably transferred to the thermosetting resin 90 .

Thermal expansion amount of upper mold: 27×10 ⁻⁶ /° C.×(150° C.-100° C.)×40 mm=54 um
Cure shrinkage amount of thermosetting resin: 1 mm x 5% = 50 um

In addition, when both the upper mold 50 and the lower mold 60 are made of aluminum, even if the thickness of each mold 50 and 60 is 20 mm, which is half the thickness, if the expansion amounts of the upper and lower molds 50 and 60 are combined, hardening will occur. Shrinkage can be exceeded.

On the other hand, when both the upper mold 50 and the lower mold 60 are made of silicon (linear expansion coefficient: 3.9×10 ⁻⁶ /° C.),
Thermal expansion amount of upper mold: 3.9×10 ⁻⁶ /° C.×(150° C.-100° C.)×40 mm=7.8 um
and is much lower than the amount of curing shrinkage.

In order to increase the curing shrinkage amount (50 μm) or more of the thermosetting resin, the thickness of the mold must be 128 mm or more at both the top and bottom. A mold with a thickness of more than 100 mm is not practical because it takes too much time for heat conduction and the tact time is greatly extended. From this point of view as well, it is preferable to use a high thermal expansion member such as aluminum for at least one of the upper mold 50 and the lower mold 60 .

Thus, according to the first embodiment, it is possible to improve the transfer accuracy of the plastic element with a simple configuration.

FIG. 15 shows the manufacturing apparatus of the second embodiment. 16 to 20 show the manufacturing process of the second embodiment. In addition, the same code|symbol is attached|subjected to the part which is common in 1st Embodiment of 2nd Embodiment, and description is abbreviate|omitted.

In the manufacturing apparatus of the second embodiment, the expansion portion 51 and the transfer portion 52 of the upper mold 50 are constructed by separate members. Specifically, the expansion section 51 is arranged between the transfer section 52 and the temperature control section 30 and is expanded by heating to constitute a pressure adjustment section for the transfer section 52 .

Further, in the second embodiment, the material of the transfer portion 52 is selected so that the expansion amount of the transfer portion 52 is smaller than the expansion amount of the expansion portion 51 . Specifically, the transfer portion 52 of the upper mold 50 is made of the same low thermal expansion material as the lower mold 60 .

For example, in the case of a microlens array in which tens of thousands of microlenses with a diameter of about 100 μm are arranged in a pattern transferred to a plastic element, it is difficult to create a shape by machining aluminum, which is a high thermal expansion member. In this case, it is preferable to process silicon (linear expansion coefficient: 3.9×10 ⁻⁶ /° C.) or glass substrate (linear expansion coefficient: 0.6×10 ⁻⁶ /° C.) by a semiconductor process. However, silicon and glass have very small coefficients of linear expansion.

Therefore, in the second embodiment, a low thermal expansion member such as silicon is used for the transfer portion 52 of the upper mold 50, and a high thermal expansion member such as aluminum is used for the expansion portion 51 of the upper mold 50, thereby improving workability of the transfer surface. and transferability can be compatible. In addition, it is possible to adapt to various resin materials by adjusting the thickness of the expansion portion 51 according to the amount of hardening shrinkage of the resin material to be transferred, or by changing the material of the expansion portion 51 .

For example, the expansion part 51 is made of aluminum (linear expansion coefficient: 27×10 ⁻⁶ /° C.), its thickness is 40 mm, the preheating temperature is 100° C., the heating temperature is 150° C., and the thermosetting resin is cured. It is assumed that the shrinkage amount is 5% and the thickness of the molded product 92 is 1 mm. In this case, as in the first embodiment, there is a relationship that the amount of thermal expansion is greater than or equal to the amount of curing shrinkage (the amount of thermal expansion≧the amount of curing shrinkage), and the pattern shape of the transfer portion 52 is formed on the thermosetting resin 90 . can be reliably transferred.

In the upper mold 50, when a pattern shape is formed on the transfer portion 52 of silicon or glass, the wafer process is used as described above, but the thickness of the transfer portion 52 is 1 mm or less, which poses a problem in thermal conductivity. no.

The action mechanism for improving the transferability in the second embodiment is the same as in the first embodiment. By doing so, a pressure corresponding to the heating temperature is applied (FIGS. 17 and 18).

Although the expansion portion 61 and the transfer portion 62 of the lower mold 60 of the second embodiment are integrally formed, the expansion portion 61 and the transfer portion 62 are formed of separate members as in the upper mold 50. may have been In this case, the expansion section 61 is arranged between the transfer section 62 and the temperature control section 40 and is expanded by heating to constitute a pressure control section for the transfer section 62 .

In the second embodiment, since the amount of expansion of the transfer portion 52 is smaller than that of the expansion portion 51, the shape of the transfer portion 52 is not only in the compression direction in which the thermosetting resin is compressed, but also perpendicular to the compression direction. Difficult to change direction. As a result, the pattern shape transfer accuracy by the transfer unit 52 can be improved not only against curing shrinkage in the compression direction of the thermosetting resin, but also against curing shrinkage in the direction perpendicular to the compression direction. can.

Further, in the second embodiment, the transfer portion 52 of the upper mold 50 is made of a low-thermal-expansion member different from the expansion portion 51, so that even if the upper mold 50 itself thermally expands, the transfer accuracy of the pattern shape is maintained. Decrease can be suppressed.

FIG. 21 shows the manufacturing apparatus of the third embodiment. FIG. 22 shows the state before heating of the upper mold that constitutes the manufacturing apparatus of the third embodiment, and FIG. 23 shows the state of the upper mold that constitutes the manufacturing apparatus of the third embodiment during heating. 24 and 25 show the manufacturing process of the third embodiment. FIG. 26 shows a plastic element obtained by the manufacturing process of the third embodiment. In addition, the same code|symbol is attached|subjected to the part which is common in 2nd Embodiment of 3rd Embodiment, and description is abbreviate|omitted.

In the manufacturing apparatus of the third embodiment, the upper mold 50 has the non-expansion portion 53 adjacent to the expansion portion 51 in the direction orthogonal to the compression direction. The non-inflatable portion 53 is arranged around the inflatable portion 51 . In the third embodiment, the inflatable portion 51 has a rectangular shape in plan view, and the non-inflatable portion 53 has a rectangular shape surrounding the inflatable portion 51 in plan view (FIG. 22).

The shape of the non-inflatable portion 53 is not particularly limited. In this embodiment, it has an annular shape with a rectangular contour in plan view.

The non-expansion portion 53 is a portion that does not expand due to heat, or that expands by a small amount even if it expands. Although the material of the non-expansion portion 53 is not particularly limited, for example, a low thermal expansion member such as silicon can be used like the lower mold 60 .

Further, in the third embodiment, the transfer section 52 is provided in the compression direction of the expansion section 51 . As a result, when the upper mold 50 is heated, the expanding portion 51 expands, the transfer portion 52 descends, and the non-expanding portion 53 does not descend. The transfer portion 52 that descends by heating forms an effective area 92A of the cured thermosetting resin (molded product) 92, and the non-expanding portion 53 that does not descend even when heated constitutes a non-effective area 92B of the molded product 92. .

Here, the effective area is an area where a desired pattern shape (or mirror surface) is desired to be formed on the plastic element. For example, in the case of an optical element, it indicates a region that performs functions such as transmission and reflection of light. In the case of an exterior part, it indicates an area where a desired appearance is desired. On the other hand, the non-effective area does not necessarily have a desired pattern shape (or mirror surface). In other words, it indicates a region in which even if transfer defects such as sink marks occur, there is no problem as an element.

In the third embodiment, the transfer portion 52 of the upper mold 50 is provided only on the portion where the effective area 92A of the molded product 92 is projected, so that the effective area 92A becomes convex with respect to the non-effective area 92B during heating. Pressurized (Fig. 23). On the other hand, in the non-effective area 92B, since the pressurizing effect due to thermal expansion does not work, the restraint of the thermosetting resin 90 on the effective area 92A is weakened.

As a result, since the thermosetting resin 90 can shrink inward, the transferability is improved in the effective area 92A inside the cured thermosetting resin 92, and the shrinkage causes sink marks in the non-effective area 92B outside. occurs. That is, the transferability of the thermosetting resin 90 can be improved by allowing the sink marks to escape to the non-effective area 92B.

Further, after the thermosetting resin 90 is cured, the outer peripheral portion (non-effective region 92B) of the solidified thermosetting resin (molded product) 92 is peeled off from the non-expansion portion 53 of the upper mold 50. The molded product 92 can be easily released from the mold during the process.

Further, in the third embodiment, since the expansion portion 51 is restricted by the surrounding non-expansion portion 53, the amount of movement of the transfer portion 52 due to thermal expansion can be increased.

FIG. 27 shows the manufacturing apparatus of the fourth embodiment. 28 to 32 show the manufacturing process of the fourth embodiment. FIG. 33 shows an example of a lower mold that constitutes the manufacturing apparatus of the fourth embodiment. FIG. 34 shows an example of a lower mold that constitutes the manufacturing apparatus of the fourth embodiment. In addition, the same code|symbol is attached|subjected to the part which is common in 2nd Embodiment of 4th Embodiment, and description is abbreviate|omitted.

In the manufacturing apparatus of the fourth embodiment, a spacer portion 63 is formed between the upper mold 50 and the lower mold 60 to regulate the gap between the upper mold 50 and the lower mold 60 (FIG. 27).

Since the production of plastic elements includes a heating process, heat accumulates in the entire apparatus as the apparatus continues to operate. change and cause variations in the dimensions of the molded product. Further, if there is temperature unevenness in the temperature control portions 30 and 40, it is conceivable that pressure unevenness will also occur in the transfer portion 52 of the upper mold 50, resulting in a decrease in the parallelism of the transfer portion 52. FIG.

In contrast, in the fourth embodiment, a spacer portion 63 is provided between the upper mold 50 and the lower mold 60 . As a result, the space between the upper mold 50 and the lower mold 60 is regulated, and the space for compressing the thermosetting resin can be adjusted, thereby improving the shape accuracy of the molded product in the thickness direction.

Specifically, the spacer portion 63 is provided annularly in plan view on the outer peripheral portion of the surface of the lower mold 60 (FIG. 33). In the heating step of FIG. 30, the transfer portion 52 of the upper mold 50 collides with the spacer portion 63 provided on the lower mold 60 while descending. As a result, the distance between the transfer portion 52 of the upper mold 50 and the transfer portion 62 of the lower mold 60 is fixed.

In addition, in the fourth embodiment, the parallelism of the transfer surface is improved by abutting against the spacer portion 63 provided on the outer peripheral portion of the lower mold 60 . As a result, it is possible to obtain the effect of further improving the shape accuracy of the molded product in the thickness direction.

In the fourth embodiment, the height of the spacer portion 63 in the direction of compression is preferably lower than the thickness of the thermosetting resin 90 in the direction of compression before heating (FIGS. 28 and 29). By setting the height of the spacer portion 63 in the direction of compression lower than the thickness of the thermosetting resin 90 before heating in the direction of compression, it is possible to prevent insufficient pressure from the upper mold 50 .

Although the material of the spacer portion 63 is not particularly limited, a material that has a coefficient of linear expansion smaller than that of the expansion portion 51 and is hard to break is preferable. For example, by integrating the lower mold 60 and the spacer portion 63 with a nickel-phosphorus alloy (linear expansion coefficient: 12×10 ⁻⁶ /° C.), the shape accuracy in the thickness direction of the molded product is further improved.

In the example of FIG. 33, the spacer portion 63 is composed of one spacer covering the entire outer periphery of the lower mold 60, but the shape of the spacer portion 63 is not limited to this form. For example, as shown in FIG. 34, a plurality of spacer portions 63 may be formed at the four corners of the lower mold 60 . By partially providing a plurality of spacer portions 63 in this manner, the spacer portions 63 are less likely to interfere when the molded product 92 is released from the mold in a post-mold opening step.

In addition, in the fourth embodiment, the spacer portion that regulates the gap between the upper mold 50 and the lower mold 60 is provided in the lower mold 60, but the position of providing the spacer is not limited to this. For example, the upper mold 50 may be formed with spacer portions, or both the upper mold 50 and the lower mold 60 may be formed with spacer portions.

Although the embodiments of the present invention have been described above, the present invention is not limited to specific embodiments, and various modifications and changes are possible within the scope of the invention described in the claims. .

<Plastic element>
The plastic element of this embodiment is manufactured by the method for manufacturing a plastic element described above. Specifically, by using the plastic element manufacturing apparatus 100 described above, the obtained hardened body (molded article) of the thermosetting resin can be the plastic element of the present embodiment.

As described above, the plastic element obtained in this manner suppresses the occurrence of sink marks in the molded article, which is a cured body of thermosetting resin, and has excellent shape accuracy (FIG. 13). Therefore, such a plastic element can be applied to applications of optical elements having a micro-/nano-order fine structure, such as microlens arrays and diffractive optical elements.

<Plastic element manufacturing equipment>
The apparatus for manufacturing a plastic element according to the present embodiment is an apparatus for manufacturing a plastic element by heating and curing a thermosetting resin to which a predetermined pattern has been transferred to form a plastic element. a driving unit that moves at least one of the molds to a position where the thermosetting resin is sandwiched between the pair of molds; and a heating unit that heats the pair of molds to cure the thermosetting resin. , at least one of the pair of molds includes a transfer portion for transferring the pattern in contact with the thermosetting resin; and an expansion portion for expanding in a compression direction in which the transfer portion compresses the thermosetting resin by heating; and the amount of expansion of the expansion portion is greater than or equal to the amount of curing shrinkage of the thermosetting resin.

Specifically, as the plastic element manufacturing apparatus of the present embodiment, a manufacturing apparatus 100 that realizes the above-described plastic element manufacturing method can be used (FIGS. 1 to 10).

As described above, in the plastic element manufacturing apparatus of the present embodiment, even if the thermosetting resin cures and shrinks in the heating process, the heat of the upper mold 50 (expansion portion 51) is reduced by using the high thermal expansion member. Due to the expansion, a compressive stress is applied in the transfer direction. Therefore, it is possible to suppress the sink mark of the molded product 92 and improve the shape accuracy (FIGS. 12 and 13).

REFERENCE SIGNS LIST 100 manufacturing apparatus 10 upper die plate 20 lower die plate 30 temperature control section 31 heat transfer section 32 heating section 33 cooling section 40 temperature control section 41 heat transfer section 42 heating section 43 cooling section 50 upper mold 51 expansion section 52 transfer section 53 Non-expansion part 60 Lower mold 61 Expansion part 62 Transfer part 63 Spacer part 70 Guide 80 Guide 90 Thermosetting resin 91 Gelled thermosetting resin 92 Solidified thermosetting resin (molded article)
92A effective area 92B non-effective area

JP 2013-75499 A

Claims (8)

A method for manufacturing a plastic element by heating and curing a thermosetting resin to which a predetermined pattern has been transferred to form a plastic element,
A step of fixing the pair of molds by sandwiching a thermosetting resin between the pair of molds;
a step of heating the pair of molds to cure the thermosetting resin;
At least one of the pair of molds,
a transfer unit that transfers the pattern in contact with the thermosetting resin;
an expansion section that expands in a compression direction in which the transfer section compresses the thermosetting resin by heating;
The method of manufacturing a plastic element, wherein the amount of expansion of the expansion portion is equal to or greater than the amount of curing shrinkage of the thermosetting resin. 2. The method of manufacturing a plastic element according to claim 1, wherein the amount of expansion of said transfer portion is smaller than the amount of expansion of said expansion portion. 3. The method of manufacturing a plastic element according to claim 1, wherein at least one of said pair of molds has a non-expansion portion adjacent to said expansion portion in a direction orthogonal to said compression direction. 4. The method of manufacturing a plastic element according to claim 3, wherein said non-expandable portion is arranged around said expandable portion. 5. The method of manufacturing a plastic element according to any one of claims 1 to 4, wherein a spacer portion is formed between said pair of molds to regulate the gap between said pair of molds. 6. The method of manufacturing a plastic element according to claim 5, wherein the height of the spacer portion in the direction of compression is lower than the thickness of the thermosetting resin in the direction of compression before heating. A plastic element manufactured by the manufacturing method according to any one of claims 1 to 6. A plastic element manufacturing apparatus for molding a plastic element by heating and curing a thermosetting resin to which a predetermined pattern has been transferred,
a pair of molds;
a driving unit that moves at least one of the pair of molds to a position where the thermosetting resin is sandwiched between the pair of molds;
a heating unit that heats the pair of molds to cure the thermosetting resin;
At least one of the pair of molds,
a transfer unit that transfers the pattern in contact with the thermosetting resin;
an expansion section that expands in a compression direction in which the transfer section compresses the thermosetting resin by heating;
An apparatus for manufacturing a plastic element, wherein the amount of expansion of the expansion portion is equal to or greater than the amount of curing shrinkage of the thermosetting resin.

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