JP5060060B2 - Mold and molding method using mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold capable of manufacturing a plastic product of good quality, containing few air bubbles, when the plastic product is manufactured by an LIM (liquid injection molding) method. <P>SOLUTION: The mold is equipped with a stationary mold and a movable mold, and an overflow catcher part is provided on at least either of the mutually opposed surfaces of the stationary mold and the movable mold in such a manner as to communicate with a gas bent of the mold and a cavity of a molded article. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a mold, and more particularly to a mold used in the LIM method.

  In general, an injection molding machine including a mold is used to mold a plastic product (or part). The mold in the injection molding machine is usually composed of a fixed mold and a movable mold, and a concavo-convex pattern corresponding to the outer shape of the plastic product to be manufactured is provided on at least one of the opposed surfaces of the fixed mold and the movable mold. Is formed. Then, by closing both molds, a cavity corresponding to the outer shape of the plastic product is defined, and a plastic product having a predetermined shape is molded by injecting resin into the cavity.

  In molds used for conventional injection molding, a gas vent (gas vent hole) that normally circulates in the cavity is formed to prevent the gas in the cavity from remaining in the molded product when the resin is injected. Has been. When resin is injected into the cavity at the time of injection molding, the air in the cavity is discharged outside from the gas vent by the pressure of the resin. At this time, the diameter of the gas vent is usually about 10 μm and the viscosity of the resin injected into the cavity is high, so that the injected resin does not flow into the gas vent.

  In addition, there are various injection molding methods, and one of them is a liquid resin injection molding (LIM: Liquid Injection Molding) method. This method is a molding method in which a raw material resin that is liquid at normal temperature is injected into a high-temperature mold and heat-cured.

  When the present inventors produced an optical component made of, for example, plastic using the LIM method, an optical component having desired optical characteristics could not be manufactured.

  An object of the present invention is to easily produce a high-quality plastic product having desired characteristics (optical characteristics, strength, durability, etc.) required for a finished product when a plastic product is molded using the LIM method. It is to provide a mold that can.

According to the first aspect of the present invention, there is provided a mold for use in molding an optical component made of a thermosetting resin by the LIM method,
A fixed mold,
With movable mold,
The mold has a gas vent that exhausts the gas in the cavity of the molded product defined between the fixed mold and the movable mold when the mold is closed; and An overflow catcher portion is provided on at least one of the opposed surfaces of the fixed die and the movable die, and the overflow catcher portion is provided so as to circulate with the gas vent and the cavity,
The liquid thermosetting resin is poured into the cavity until the thermosetting resin is filled into the overflow catcher portion, whereby the gas in the cavity enters the overflow catcher portion together with the thermosetting resin. A mold is provided that is extruded.
According to the second aspect of the present invention, in a molding method for molding an optical component made of a thermosetting resin by a LIM method using a mold,
The mold is connected to a cavity for molding the molded product body, to the cavity, and to a gate for introducing the liquid thermosetting resin from the cavity, to the cavity and in the cavity. An overflow catcher portion that receives the thermosetting resin that has overflowed from the gas, and a gas vent that discharges the gas in the cavity to the outside,
The thermosetting resin is poured into the cavity through the gate until the thermosetting resin is filled in the overflow catcher portion, whereby the gas in the cavity is discharged together with the thermosetting resin to the overflow catcher. There is provided a molding method characterized by extruding into a part and then solidifying the thermosetting resin.

  The present inventors produced a plastic optical lens by the conventional LIM method, but the molded optical lens had burrs at a position corresponding to the gas vent. This is presumably because the resin flowed into the gas vent during injection molding because the thermosetting resin (silicone) used had low viscosity and high fluidity. Thus, when a burr | flash generate | occur | produces in a molded article, the process which removes a burr | flash for every molded article will be needed, and will hinder mass-productivity improvement.

  Therefore, in order to prevent burrs from being generated in the molded optical lens, that is, to prevent the resin from flowing into the gas vent, the diameter of the gas vent is made narrower (about 5 μm) than before, and injection molding is performed. Produced. However, when the molded optical lens was inspected, no burr was generated in the optical lens, but bubbles were present inside the optical lens, particularly in a region opposite to the gate into which the resin was poured. This is presumably because the gas vent was narrowed and injection molded, so that air in the cavity could not escape and bubbles remained in the molded product. As described above, when bubbles are included in the optical lens, the transmittance, refractive index, and the like of the optical lens change, so that desired optical characteristics cannot be obtained.

  In addition, if bubbles exist in a plastic molded product as well as the optical lens, the required properties (strength, durability, etc.) of the molded product may not be obtained. In addition, when there is a possibility that air bubbles remain in the molded product, it is necessary to inspect all the molded products, which is not preferable in terms of mass productivity. Furthermore, if injection molding is performed under unreasonable molding conditions so that bubbles do not remain in the molded product, there is a risk that defects such as variations may occur in the molded product.

  Therefore, in order to solve the above-mentioned problems, the inventors of the present invention have disclosed a molded product defined when a fixed mold and a movable mold are closed inside a mold used for molding a plastic product by the LIM method. An overflow catcher in circulation with the cavity was provided. The term “overflow catcher” as used herein refers to a resin storage chamber that circulates through the cavity of a molded product defined during injection molding and into which injected resin flows through the cavity. In the mold of the present invention, an overflow catcher portion is provided on at least one of the opposing surfaces of the fixed mold and the movable mold, and when the mold is closed, the overflow catcher portion provided on one mold An overflow catcher is defined by the surface of the other mold facing the mold or the overflow catcher portion provided on the other mold facing the mold.

  When a molded product is produced by the LIM method using the mold of the present invention, when resin is injected into the cavity, the cavity is first filled with resin, and then the resin flows into the overflow catcher. At that time, the gas in the cavity is pushed out together with the resin to the overflow catcher. The gas pushed out by the overflow catcher is discharged to the outside through a gas vent that circulates in the overflow catcher. As described above, when the mold of the present invention is used, the gas in the cavity is pushed out together with the resin to the overflow catcher, so that almost no gas remains in the cavity. Therefore, almost no bubbles remain in the molded product.

  And after taking out a molded product from a metal mold | die, if the unnecessary molded part solidified by the gate injecting resin, an overflow catcher, etc. is removed from the molded product, the desired plastic product which hardly contains a bubble will be obtained. At this time, the molded part immediately after taking out from the mold as described above is in a state where the molded part solidified by the overflow catcher is attached, but since this molded part has the same shape in all the molded parts, gates, etc. It can be mechanically cut in the same manner as the unnecessary molded part solidified in step (b). Therefore, it is not necessary to individually inspect all the molded products for burr removal processing and the presence or absence of bubbles, so that mass productivity is improved.

  In the mold of the present invention, it is preferable that the overflow catcher portion is provided in the vicinity of the final filling position of the thermosetting resin in the cavity. In the molding process using the mold of the present invention, as described above, the gas in the cavity is pushed out to the overflow catcher by the thermosetting resin injected into the cavity, and the gas in the cavity is extracted. By providing the vicinity of the final filling position of the thermosetting resin in the cavity, the gas in the cavity can be surely extracted.

  In the mold of the present invention, it is preferable that the thermosetting resin to be introduced is a transparent resin. When molding an optical component such as a lens made of a transparent resin by the LIM method, if the molded product contains air bubbles, its optical properties (transmittance, refractive index, etc.) deteriorate, so there are almost no air bubbles. It is preferable to use the mold of the present invention capable of producing a molded product. In addition, this invention is not limited to this, You may use opaque resin as a thermosetting resin to flow in. By using the mold of the present invention, it is possible to produce a high-quality resin product that does not contain air bubbles. Therefore, properties such as strength and durability of the molded product can be improved, and molding made of an opaque resin by the LIM method. It is also suitable when producing a product.

  In the metal mold | die of this invention, it is preferable that the viscosity of the said thermosetting resin is 1500-15000d * pas at 25 degreeC. In particular, the thermosetting resin is preferably silicone. Other than silicone, examples of the thermosetting resin having the above properties include phenol resin, polyester resin, epoxy resin, area resin, melamine resin, and the like.

  According to the mold of the present invention, the overflow catcher that circulates with the cavity in which the molded product is molded is provided, and the gas in the cavity is extruded together with the resin to the overflow catcher during the injection molding. No bubbles remain on the surface. Therefore, when a molded product is produced using the mold of the present invention, a molded product made of a very good thermosetting resin can be produced.

  In addition, when a molded product is produced using the mold of the present invention, an unnecessary molded part solidified by an overflow catcher is attached to the molded product immediately after being taken out from the mold. Can be removed mechanically in the same manner as the unnecessary molded portion solidified by a gate or the like, so that mass productivity can be improved.

  Hereinafter, an embodiment of a mold of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

  In the examples, the optical lens was molded by the LIM method, and silicone was used as a material for forming the optical lens.

[Mold structure]
The schematic structure of the mold part of the injection molding machine used in the examples is shown in FIG. FIG. 1 is a schematic cross-sectional view showing a state in which the mold is closed. As shown in FIG. 1, the mold 100 of this example includes a movable mold 12 and a fixed mold 22. In the injection molding machine used in the examples, the parts other than the mold have the same structure as the conventionally used injection molding machine, and the movable mold 12 is attached to a movable platen (not shown) and fixed. The mold 22 is attached to a fixed platen (not shown), and the movable platen is provided with a protruding rod (not shown) for taking out a molded product from the mold.

  On the surface of the movable mold 12 on the fixed mold 22 side, there are a movable runner section 14, a movable molding section 16, a movable gate section 15 connecting the movable runner section 14 and the movable molding section 16, and an overflow catcher section 17. Is formed. In this example, the overflow catcher portion 17 is provided on the side opposite to the movable gate portion 15 side of the movable molding portion 16 (the final filling position of the thermosetting resin).

  As shown in FIG. 1, the overflow catcher portion 17 includes a resin receiving portion 17 a that stores the resin pushed out from the cavity, and a flow path portion 17 b that connects the resin receiving portion 17 a and the movable molding portion 16. In this example, the depth of the flow path portion 17b of the overflow catcher 17 is formed shallower than the depth of the resin receiving portion 17a. The molded part solidified in the flow path part 17b corresponds to the part where the projecting pin hits when the molded product is taken out from the mold by the ejection method, and the thickness of the molded part solidified in the flow path part 17b is By making it thinner than the thickness of the molded part solidified by the resin receiving part 17a, it becomes easy to stick the protruding pin. In addition, this invention is not limited to this, You may make the depth of the flow-path part 17b and the depth of the resin receiving part 17a into the same depth.

  On the other hand, the fixed mold 22 is provided with a sprue bush 33 into which a thermosetting resin is injected, as shown in FIG. Further, as shown in FIG. 1, a fixed runner part 24, a fixed gate part 25, and a fixed molding part 26 are formed on the surface of the fixed mold 22 on the movable mold 12 side. It is formed in a region facing the movable runner part 14, the movable gate part 15 and the movable molding part 16 of the mold 12.

  In the mold of the present invention, as shown in FIG. 1, the runner 34 is defined by overlapping the opening of the movable runner part 14 and the opening of the fixed runner part 24 by closing the mold. Similarly, a gate 35 is defined by the movable gate portion 15 and the fixed gate portion 25, and a cavity 36 is defined by the movable molding portion 16 and the fixed molding portion 26. In this example, an overflow catcher 37 is defined by the overflow catcher portion 17 of the movable mold 12 and the surface area of the fixed mold 22 facing it. Further, in this example, as shown in FIG. 1, a gas vent 38 is provided on the opposite side of the overflow catcher 37 from the cavity 36 side.

  In this example, as will be described later, since the molded part solidified by the overflow catcher 37 is finally cut, all the gas pushed out from the cavity 36 to the overflow catcher 37 is discharged through the gas vent 38. There is no need, and the overflow catcher 37 may remain as bubbles. Therefore, the diameter (size) of the gas vent 38 may be made smaller. Further, the diameter of the gas vent 38 may be increased to some extent in order to perform degassing more efficiently. In this case, the resin flows into the gas vent 38 and burrs are generated on the gas vent 38 side of the overflow catcher 37, but there is no problem because the molded part solidified by the overflow catcher 38 is cut. That is, the diameter (size) of the gas vent 38 circulating with the overflow catcher 37 is arbitrary as long as the resin does not jump out of the mold, and the diameter can be appropriately set according to the resin used. .

  Further, in the mold 100 of this example, the overflow catcher portion 17 is arranged such that the distance between the flow path portion 17b of the overflow catcher 37 and the surface of the fixed mold 22 facing the same is the same as the diameter of the gate 35. The flow path part 17b was formed. When the flow path portion 17b is formed in such a size, when the unnecessary molded portion solidified by the overflow catcher 37 is cut from the molded product taken out from the mold, the same means as the molded portion solidified by the gate 35 and Since it can cut | disconnect using a method, mass-productivity can be improved. In this example, the sizes of the flow path portion 17b and the resin receiving portion 17a are set so that the capacity of the overflow catcher 37 defined when the mold 100 is closed is about 50% of the capacity of the cavity 36. did,

  Note that the size and shape of the overflow catcher portion 17 can be appropriately set according to the shape, capacity, etc. of the cavity 36. In particular, it is preferable to set the size and shape of the overflow catcher portion 17 so that the capacity of the overflow catcher 37 is about 10 to 100% of the capacity of the cavity 36. Further, the width (or diameter) of the overflow catcher 37 is preferably about 10 times or more the diameter of the gas vent 38. By providing the overflow catcher portion 17 so that the capacity and dimensions of the overflow catcher 37 are in the above range, the gas in the cavity 36 is discharged to the outside through the overflow catcher 37 and the gas vent 38 more efficiently and reliably. be able to.

[Optical Lens Molding Method and Manufacturing Method]
Next, a molding method and a manufacturing method of the optical lens using the mold of this example will be described with reference to FIG. FIGS. 2A to 2C are diagrams showing the procedure of the molding process in the example. 2 are schematic plan views of a runner, a gate, a cavity, and an overflow catcher as viewed from the AA side in FIG. In FIG. 2, the gas vent 38 that circulates with the overflow catcher 37 is omitted in order to simplify the description.

  First, the temperature inside the mold was adjusted to a high temperature (about 150 ° C.). Next, a thermosetting resin 40 (silicone) was injected into the runner 34 through the spray bush 33 of the fixed mold 22. The thermosetting resin 40 injected into the runner 34 flows into the cavity 36 through the gate 35 (the state shown in FIG. 2A). At this time, since the mold is temperature-controlled, the thermosetting resin 40 starts to solidify when it is injected, but does not solidify in the flowing region.

  The thermosetting resin 40 that has flowed into the cavity 36 is filled into the cavity 36 while pushing the air in the cavity 36 to the overflow catcher 37 (the state of FIG. 2B). The air pushed out to the overflow catcher 37 is discharged to the outside through the gas vent 38. Next, the thermosetting resin 40 that flowed into the cavity 36 by further applying pressure was molded into a product shape.

  Further, when the thermosetting resin 40 is poured into the cavity 36, the thermosetting resin 40 in the cavity 36 flows into the overflow catcher 37. Next, the thermosetting resin 40 was poured into the cavity 36 until the overflow catcher 37 was filled with the thermosetting resin 40. Then, when the overflow catcher 37 was filled with the thermosetting resin 40, the molding process was finished. At this point, the flow of the thermosetting resin 40 is lost, and the entire region filled with the thermosetting resin 40 is solidified (state shown in FIG. 2C). In this example, an optical lens was molded as described above.

  Note that the air pushed out to the overflow catcher 37 is discharged to the outside through the gas vent 38, but not completely discharged, and even if some air bubbles 50 remain in the overflow catcher 37 as shown in FIG. good. Since the molded part 47 solidified by the overflow catcher 37 is a part cut from the molded product, the air bubbles 50 may remain in the overflow catcher 37.

  After molding the optical lens by the above molding method, the mold was returned to room temperature, the mold was opened, the molded product was ejected by the ejecting pin, and the molded product was taken out from the mold. At this time, the molded product was taken out by pushing an eject pin (not shown) provided on the gate 35 and the overflow catcher 37 against the molded product. Finally, the molded portion solidified by the runner 34, the gate 35 and the overflow catcher 37 (solidified portions 44, 45 and 47 in FIG. 2C) was cut to obtain an optical lens of this example. When the optical lens produced in this example was examined, bubbles were not observed in the lens, and desired optical characteristics were obtained.

[Comparative example]
In the comparative example, an optical lens was molded by the LIM method using a conventional mold without an overflow catcher. As a material for forming the optical lens, silicone was used as in the example. In this example, the diameter of the gas vent was made sufficiently small (about 5 μm or less) so that silicone would not flow into the gas vent. Other than that, the optical lens was produced like the Example. As a result, bubbles remained in the optical lens, and desired optical characteristics could not be obtained. The reason why bubbles remain in the optical lens will be described with reference to FIG. FIG. 3 is a flowchart of the molding process in the comparative example. Here, in order to simplify the description, the gas vent flowing through the cavity is omitted.

  First, when the thermosetting resin 40 is injected into the runner 34 through the spray 13 of the fixed mold 12, the thermosetting resin 40 injected into the runner 34 flows into the cavity 36 through the gate 35 (FIG. 3A ) State). The thermosetting resin 40 that has flowed into the cavity 36 is filled into the cavity 36 while pushing out the air 51 in the cavity 36 to the side opposite to the gate 35 (state of FIG. 3B). At this time, the air in the cavity 36 is discharged to the outside through a gas vent (not shown) that circulates with the cavity 36. Next, the thermosetting resin 40 that has flowed into the cavity 36 by further applying pressure is formed into a product shape. When the thermosetting resin 40 is filled in the overflow catcher 38, the molding process is finished (the state shown in FIG. 3C).

  However, in this example, since the diameter of the gas vent is very small, air cannot escape from the inside of the cavity 36, and bubbles 52 remain in the molded product 56 as shown in FIG. For this reason, in this example, bubbles remain in the molded optical lens, and desired optical characteristics cannot be obtained.

  In the above embodiment, the overflow catcher portion is formed on the surface of the movable mold, and the overflow catcher is defined by the overflow catcher portion of the movable mold and the surface of the fixed mold opposite to the overflow catcher portion. Is not limited to this. An overflow catcher part may be formed on the surface of the fixed mold, and the overflow catcher may be defined by the overflow catcher part of the fixed mold and the surface of the movable mold opposed to the overflow catcher part. In addition, each of the fixed mold and movable mold facing each other has a predetermined shape of overflow catcher section, and the fixed mold overflow catcher section and the movable mold overflow catcher section define an overflow catcher. May be.

  In the above embodiment, the optical lens has been described as an example, but the present invention is not limited to this. In the case of producing a molded article using a thermosetting resin having a low viscosity, a high-quality molded article containing no bubbles can be produced by using the mold of the present invention. Specifically, it is also effective when a molded product is produced using a thermosetting resin having a viscosity of 1500 to 15000 d · pas at 25 ° C., such as phenol resin, polyester resin, epoxy resin, area resin, melamine resin, etc. It is.

  In the above embodiment, an example in which a transparent molded article (optical lens) is produced has been described, but the present invention is not limited to this. The mold of the present invention can be applied to an opaque molded product. Even in that case, since a high-quality molded product containing no air bubbles can be obtained, it is possible to improve properties such as strength and durability of the molded product.

  In the above embodiment, the overflow catcher is provided on the side opposite to the gate side of the cavity. However, the present invention is not limited to this, and can be provided at any position according to the shape of the molded product. In order to more reliably push the gas in the cavity to the overflow catcher, it is preferable to provide the gas in the vicinity of the final filling portion of the thermosetting resin in the cavity. Therefore, if the final filling position of the thermosetting resin is near the cavity gate, an overflow catcher may be provided near the cavity gate.

  Moreover, although the example which provided one overflow catcher was demonstrated in the said Example, this invention is not limited to this, You may provide a some overflow catcher.

  When a molded product is molded using the mold of the present invention, a high-quality molded product containing almost no air bubbles can be provided. Therefore, the mold of the present invention is an optical lens made of a thermosetting resin or the like. Thus, it is suitable as a mold for use in molding a molded product that is greatly deteriorated in the properties of the molded product by containing bubbles.

FIG. 1 is a schematic cross-sectional view of a mold used in the examples. 2A to 2C are diagrams for explaining a molding process in the embodiment. 3A to 3C are views for explaining a molding process in a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Movable metal mold | die 14 Movable runner part 15 Movable gate part 16 Movable molding part 17 Overflow catcher part 17a Resin receiving part 17b Flow path part 22 Fixed mold 24 Fixed runner part 25 Fixed gate part 26 Fixed molding part 33 Sprue bush 34 Runner 35 Gate 36 Cavity 37 Overflow catcher 38 Gas vent

Claims (9)

A mold used when molding an optical component made of a thermosetting resin by the LIM method,
A fixed mold,
With movable mold,
The mold has a gas vent that exhausts the gas in the cavity of the molded product defined between the fixed mold and the movable mold when the mold is closed; and An overflow catcher portion is provided on at least one of the opposed surfaces of the fixed die and the movable die, and the overflow catcher portion is provided so as to circulate with the gas vent and the cavity,
The liquid thermosetting resin is poured into the cavity until the thermosetting resin is filled into the overflow catcher portion, whereby the gas in the cavity enters the overflow catcher portion together with the thermosetting resin. A mold characterized by being extruded.   The mold according to claim 1, wherein the overflow catcher portion is provided near a final filling position of the thermosetting resin in the cavity. The mold according to claim 1 or 2, wherein a capacity of the overflow catcher portion is 10 to 100% of a capacity of the cavity. In a molding method for molding an optical component made of a thermosetting resin by a LIM method using a mold,
  The mold includes a cavity for molding the molded product body, a gate communicating with the cavity, and a liquid thermosetting resin introduced from the cavity, communicating with the cavity and from within the cavity. An overflow catcher portion that receives the thermosetting resin that has overflowed, and a gas vent that discharges the gas in the cavity to the outside.
  The thermosetting resin is poured into the cavity through the gate until the thermosetting resin is filled in the overflow catcher portion, whereby the gas in the cavity is discharged together with the thermosetting resin and the overflow catcher. A molding method characterized by extruding to a part and then solidifying the thermosetting resin. The molding method according to claim 4, wherein the overflow catcher portion is provided near a final filling position of the thermosetting resin in the cavity. The molding method according to claim 4 or 5, wherein a capacity of the overflow catcher portion is 10 to 100% of a capacity of the cavity. The molding method according to claim 4, wherein the thermosetting resin is a transparent resin. The molding method according to any one of claims 4 to 7, wherein the thermosetting resin has a viscosity of 1500 to 15000 d · pas at 25 ° C. The molding method according to claim 4, wherein the thermosetting resin is silicone.

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