JP2024043039A - injection mold - Google Patents

Abstract

[Problem] To suppress the buildup of deposits in air vent grooves and to facilitate the removal of built-up deposits. [Solution] A mold for molding by injecting molten resin material into a cavity formed by abutting a fixed mold and a movable mold at their parting surfaces, the parting surfaces of at least one of the fixed mold and the movable mold are provided with a texture that reduces surface energy, a first air vent groove that communicates with an end of the cavity at a first groove depth to allow gas inside the cavity to flow, and a second air vent groove that has one end that communicates with the first air vent groove at a second groove depth that is deeper than the first groove depth and has the other end that communicates with the outside of the mold. [Selected Figure] Figure 6

Description

The present invention relates to an injection mold.

In an injection mold for manufacturing optical disk substrates, the land portion of the gas vent formed between the end of the nickel stamper attached to the mold cavity surface and the mold cavity block, and/or corresponding to this land portion. A fluororesin coating film is formed on the stamper part, the thickness of the fluororesin coating film is in the range of 5 to 10 μm, and the clearance for gas venting of the gas vent after the coating film is formed is 5 to 10 μm. An injection mold for manufacturing an optical disc substrate having a thickness in the range of 15 μm is known (Patent Document 1).

A mixture of a metal powder and a binder containing a thermoplastic polymer material is used, and has a pair of surfaces, an opening on one of the pair of surfaces, and a 0.0-. a molding step of molding a molded body having at least one groove with a tapered structure having pointed ends at positions separated by 1 mm or more; a heat treatment process of removing the binder and sintering the molded body to obtain a sintered body; A method for manufacturing a gas vent member is also known that includes a polishing step of polishing the other surface of the body until the tip is exposed (Patent Document 2).

Japanese Patent Application Laid-Open No. 11-34121 JP2020-66224A

The present invention suppresses the buildup of deposits in the air vent grooves and makes it easier to remove any accumulated deposits.

In order to solve the problem, the injection mold according to claim 1,
A mold for molding by injecting a molten resin material into a cavity formed by bringing a fixed mold and a movable mold into contact at their parting surfaces,
A texture is formed on the parting surface of at least one of the fixed mold and the movable mold to reduce surface energy, and a first groove depth is connected to the end of the cavity to allow gas in the cavity to flow. a second air vent groove, one end of which communicates with the first air vent groove at a second groove depth that is deeper than the first groove depth, and the other end of which communicates with the outside of the mold. Ta,
It is characterized by

The present invention relates to an injection molding die according to the first aspect of the present invention,
the texture is composed of a dimple group consisting of a plurality of dimples formed on the bottom of the first air vent groove;
It is characterized by:

The invention according to claim 3 is the injection mold according to claim 2,
The dimple has a dimple depth that is the same as the first groove depth.
It is characterized by

The invention according to claim 4 is the injection mold according to claim 3,
The dimple group is formed by a plurality of dimples arranged at a lattice angle of 30 degrees to 75 degrees,
It is characterized by

The invention described in claim 5 is the injection molding die described in claim 1,
The texture is composed of grooves having a nano-periodic structure formed at the bottom of the first air vent groove.
It is characterized by:

The invention according to claim 6 is the injection mold according to claim 1,
The texture is formed by removing material at the bottom of the first air vent groove by irradiating with an ultra-short pulse laser.
It is characterized by

The seventh aspect of the present invention provides a mold for injection molding according to any one of the first to fifth aspects,
The first air vent groove has a groove width of 1.0 mm or more and 2.0 mm or less, and a first groove depth of 0.003 mm to 0.01 mm.
It is characterized by:

The invention according to claim 8 is the injection mold according to any one of claims 1 to 6,
the molten resin material is a thermoplastic crystalline resin;
It is characterized by

According to the invention described in claim 1, it is possible to suppress the accumulation of deposits in the air vent groove and to facilitate the removal of the accumulated deposits.

According to the second aspect of the invention, by partially changing the cross-sectional area of the groove bottom, the gas flow can be changed to trap the deposit.

According to the third aspect of the present invention, deposits can be trapped in the dimples, and clogging of the first air vent groove due to deposits can be suppressed.

According to the invention set forth in claim 4, it is possible to efficiently trap deposits in the dimples and to suppress clogging of the first air vent groove due to deposits.

According to the invention set forth in claim 5, by partially changing the cross-sectional area of the groove bottom, the gas flow can be changed and the deposit can be captured.

According to the invention set forth in claim 6, a texture can be formed within the air vent groove.

According to the seventh aspect of the invention, gas can be guided from the first air vent groove to the second air vent groove while suppressing the generation of burrs.

According to the eighth aspect of the invention, it is possible to use a resin material that easily generates burrs.

FIG. 1 is a schematic cross-sectional view of an injection mold according to the present embodiment. (a) is a schematic plan view showing the stationary side of the injection mold according to the present embodiment, looking toward the parting surface side, and (b) is a schematic partial cross-sectional view showing an air vent groove. FIG. 3 is a perspective view of the air vent insert, looking toward the first air vent groove. (a) is a schematic plan view showing a dimple group of the first air vent groove, and (b) is a schematic cross-sectional view. 1A is a schematic plan view showing a texture according to a modified example of the first air vent groove, and FIG. 1B is a partially enlarged schematic view illustrating the texture according to the modified example. FIG. 4A is a diagram for explaining gas flow in a first air vent groove, and FIG. 4B is a diagram for explaining gas flow in an air vent groove. 3 is a schematic plan view showing a first air vent groove according to Example 1. FIG. FIG. 7 is a schematic plan view showing a first air vent groove according to Example 2. FIG. FIG. 2 is a perspective view showing an example of a molded product according to an example together with a runner. FIG. 3 is a diagram showing the surface condition of the groove bottom of the first air vent groove according to Example 1 after 2000 times of molding. FIG. 7 is a diagram showing the surface condition of the groove bottom of the first air vent groove according to Example 2 after 2000 times of molding. It is a figure which shows the surface state of the air vent groove of the comparative example after 2000 times of molding in which the texture is not formed.

Next, specific examples of embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.
In the explanation using the drawings below, it should be noted that the drawings are schematic and the proportions of each dimension may differ from the actual ones. Illustrations of parts other than members are omitted as appropriate.

(1) Overall Configuration of Injection Molding Die FIG. 1 is a schematic cross-sectional view of an injection molding die 1 according to this embodiment.
The overall configuration of the injection molding die 1 will now be described with reference to the drawings.

As shown in FIG. 1, the injection mold 1 consists of a fixed side mold 10 and a movable side mold 20 that are joined at a contact surface (hereinafter referred to as parting surface PL). A cavity C filled with resin is formed between the side die 20 and the side mold 20 .

The fixed side mold 10 includes a fixed side mounting plate 11, a fixed side mold plate 12 on which a nested storage part is formed, and a fixed side mold plate on which a part of a cavity surface and a parting surface P forming a part of a cavity C are formed. It consists of a side insert 13 and an air vent insert 14 having a first air vent groove 41 formed at one end.

The fixed side mounting plate 11, the fixed side mold plate 12 on which the fixed side insert 13 and the air vent insert 14 are arranged are joined in order, and the fixed side mounting plate 11 is provided with a locate ring 15 to which resin is supplied.
The fixed side mounting plate 11 is provided with a sprue bush 17 in which a sprue 16 is formed, which communicates with the locate ring 15 and into which the molten resin initially flows. Furthermore, a runner groove is formed in the stationary insert 13 to form one side of the runner 18 through which the molten resin injected from the sprue 16 flows toward the cavity C. A gate 19 for filling the cavity C with molten resin is formed at the tip of the runner groove.

The movable side mold 20 is joined to the movable side mounting plate 21 and the stripper plate 23 which is attached to the movable side mounting plate 21 via a spacer block 22 and is movable in the moving direction of the movable side mold 20. It consists of a movable template 24. A movable insert 26 having a core 25 desired on the cavity surface of the fixed insert 13 is attached to the movable template 24 on the side of the fixed mold 10 .

The parting surface PL of the movable side insert 26 has a second air vent groove 42 that communicates with one end of the first air vent groove 41 and exhausts gas generated in the cavity C to the outside of the mold, and a second air vent groove 42 that surrounds the cavity C. An annular air vent groove 50 is formed and communicates with the second air vent groove 42 . The annular air vent groove 50 communicates with a gas escape hole 60 that extends from the movable insert 26 through the movable mold plate 24 and connects to the outside. A vacuum pump M (not shown) is connected to the gas escape hole 60, and the gas that collects in the annular air vent groove 50 from the air vent groove 40 is sucked and discharged to the outside of the mold.

The movable mold 20 is provided with an ejector mechanism 30. The ejector mechanism 30 includes a pair of ejector plates 33 that are movable along an ejector guide pin 31 and a support pin 32 installed between the movable side mounting plate 21 and the stripper plate 23, and an ejector plate provided on the ejector plate 33. 33 and a plurality of ejector pins 34 that move together.

The ejector plate 33 is normally positioned in a retracted position by a biasing means (not shown), and when the mold is opened, it is moved forward by a driving means (not shown) to cause the ejector pin 34 to protrude from the core 25 and move into the cavity C. The molded product is projected to separate the product from the core 25.

(2) Air vent structure and gas discharge FIG. 2(a) is a schematic plan view showing the fixed side of the injection mold 1 according to the present embodiment, viewed from the parting surface PL side, and FIG. 2(b) is an air vent FIG. 3 is a perspective view of the air vent insert 14 shown with a view toward the first air vent groove 41; FIG. 4(a) is a schematic plan view showing a group of dimples in the first air vent groove 41; (b) is a schematic cross-sectional view.
Hereinafter, the configuration of the air vent groove 40 in the injection mold 1 and the gas discharge will be explained with reference to the drawings.

(2.1) Air Vent Groove The injection mold 1 according to this embodiment is provided with an air vent structure for discharging gas generated within the cavity C to the outside of the mold. As schematically shown in Fig. 2, the air vent structure communicates with the end of the cavity C, and allows the gas generated within the cavity C to flow outside the cavity C while suppressing the outflow of resin that forms burrs from within the cavity C. an annular air vent groove 50 that is formed to surround the cavity C and communicates with a plurality of air vent grooves 40 (only one air vent groove 40 is shown in FIG. 2); The annular air vent groove 50 includes a gas escape hole 60 (see FIG. 1) that communicates with the annular air vent groove 50 and guides the gas flowing inside the annular air vent groove 50 to the outside of the mold.

As shown in FIG. 2(b), the air vent groove 40 is composed of a first air vent groove 41 that is connected to the end of the cavity C, and a second air vent groove 42 that has one end connected to the first air vent groove 41 and the other end connected to the annular air vent groove 50 that is formed in a ring shape surrounding the cavity C.

As shown in FIG. 3(a), the first air vent groove 41 is formed as a groove with a first groove depth D1 and groove width W1 that communicates with the surface of one end of the air vent insert 14 facing the parting surface PL. Specifically, it is formed as a concave groove with a groove width W1 of 1 mm to 20 mm, a groove depth D1 of 0.003 to 0.01 mm, and a groove length (land length) L1 of 1 mm to 3 mm. In particular, the groove depth D1 is formed to a depth that allows gas generated in the cavity C to flow while suppressing the outflow of resin that becomes burrs from the cavity C. In particular, when the resin material is a crystalline resin, such as PPS (polyphenylene sulfide), the mold temperature is high at 130°C to 150°C, and the viscosity of the molten resin is low, so that the molten resin is likely to overflow, and the groove depth D1 is preferably 0.003 to 0.007 mm, more preferably 0.003 to 0.005 mm.

As shown in FIG. 3(b), the groove bottom 41a of the first air vent groove 41 is formed with a texture that reduces surface energy. As shown in FIG. 4, the texture is formed as a dimple group consisting of a plurality of dimples DP. The dimple DP has a diameter d of 0.005 to 0.02 mm and a depth t1 of 0.003 to 0.01 mm, and each dimple DP has a lattice angle with respect to the gas flow direction (see arrow R in FIG. 4). The dimples are arranged at an angle of 30 degrees to 75 degrees to form a dimple group.

Such a dimple DP can be formed, for example, by irradiating with a femtosecond laser pulse having a predetermined pulse width at a fluence near the laser ablation threshold to remove the material of the dimple DP portion. A galvano scanner or a polygon scanner may be used for laser beam scanning. Methods for removing material in the dimple DP include a method using a condensed spot with a diameter near the dimple DP, a method of laser scanning the inside of the dimple DP with a condensed spot having a diameter smaller than the dimple DP, and a method using a diffractive optical element. Alternatively, a method of removing the dimple DP by forming a plurality of circular condensing spots with a diameter near the dimple DP using a spatial optical phase modulator, etc.

It is known that by forming such a microtexture, the contact angle of the material surface is increased and the state changes from hydrophilic to water repellent. In this embodiment, by forming a dimple group consisting of a plurality of dimples DP in the groove bottom 41a of the first air vent groove 41, the attachment of deposits formed by liquefying volatile components and gas components generated from the molten resin is suppressed. At the same time, the adhered liquid or deposits that have been cooled and condensed are easily peeled off by the gas flow flowing through the first air vent groove 41.

Further, as shown in FIG. 4(b), the dimple DP is formed by partially changing the cross-sectional area of the air vent in the cross section in the direction intersecting the gas flow direction in the first air vent groove 41. 1. The flow of gas within the air vent groove 41 can be changed. This allows the deposit to be captured within the dimple DP.

"Variation"
FIG. 5(a) is a schematic plan view showing a texture according to a modified example of the first air vent groove 41, and FIG. 5(b) is a partially enlarged schematic diagram illustrating the texture according to the modified example.
The groove bottom 41a of the first air vent groove 41A according to the modified example is formed with a texture that reduces surface energy. The texture is composed of grooves with a nanoperiodic structure, as shown in FIG. 5(a). Specifically, as schematically shown in FIG. 5(b), the entire groove bottom 41a has a width w of 0.0005 mm to 0.02 mm along the gas flow direction in the first air vent groove 41. Vertical grooves GR having a depth t2 of 0.005 to 0.05 mm are formed so as to repeat at a nanopitch p in the width direction of the groove bottom 41Aa.

Such vertical grooves GR can be formed, for example, by irradiating a femtosecond laser pulse having a predetermined pulse width at a fluence near the laser ablation threshold to remove material from the dimple DP portion in a direction perpendicular to the deflection direction of the incident light.

The vertical groove GR of the nano periodic structure partially increases the cross-sectional area of the air vent in the cross section in the direction intersecting the flow direction of the gas flow in the first air vent groove 41A, and increases the flow rate of the gas flow in the first air vent groove 41A. The flow can be changed. Thereby, the deposit can be trapped within the longitudinal groove GR of the nanoperiodic structure.

2(b), the second air vent groove 42 is formed as a gas exhaust passage with one end communicating with the first air vent groove 41 at a second groove depth D2 deeper than the first groove depth D1 and the other end communicating with the annular air vent groove 50. Specifically, the second air vent groove 42 is formed as a recessed groove with a groove width W2 (not shown) of 1 mm to 20 mm and a groove depth D2 of 1 mm to 2 mm deeper than the groove depth D1 of the first air vent groove 41, on the parting surface PL of the movable insert 26, facing the first air vent groove 41.

The second air vent groove 42 is deeper than the first groove depth D1 at the downstream end in the gas flow direction of the first air vent groove 41, which is formed with a shallow first groove depth D1 so as to suppress outflow of molten resin. The grooves communicate at the second groove depth D2 to increase the amount of gas discharged. Further, the downstream end of the second air vent groove 42 in the gas flow direction communicates with the annular air vent groove 50 and discharges the gas generated within the cavity C to the outside of the mold via the gas escape hole 60.

(2.2) Gas Discharge FIG. 6A is a diagram illustrating the flow of gas in the first air vent groove 41, and FIG. 6B is a diagram illustrating the flow of gas in the air vent groove 40.
When the molten resin is filled into the cavity C from the gate 19 (see FIG. 1), volatile components and gas components (hereinafter simply referred to as gas) generated from the air and molten resin in the cavity C are moved in the direction indicated by the arrow in FIG. The air flows into the first air vent groove 41 as indicated by R1.
A part of the gas flowing into the first air vent groove 41 flows along the depression of the dimple DP formed in the groove bottom 41a of the first air vent groove 41, as schematically shown by arrow R2 in FIG. 6(a). distributed. At this time, the gas tends to stay in the depression of the dimple DP, becomes liquefied or cooled, condenses, and becomes easily trapped. Since such dimples DP are formed as a dimple group with a lattice angle of 60 degrees, for example, the gas flowing through the first air vent groove 41 traps volatile components and gas components as deposits in the dimple group, and air The air flows into the second air vent groove 42 .

The air that has flowed into the second air vent groove 42 flows within the second air vent groove 42 toward the communication portion of the annular air vent groove 50 (see arrow R3 in FIG. 6(b)).
A gas relief hole 60 (see FIG. 1) communicates with the annular air vent groove 50, and the air flowing into the annular air vent groove 50 from the second air vent groove 42 is sucked by the vacuum pump M from the gas relief hole 60 and is sucked out of the mold. is discharged to.

As described above, according to the injection mold 1 according to the present embodiment, the texture that lowers the surface energy formed on the groove bottom 41a of the first air vent groove 41 communicating with the cavity C reduces volatile components and gas formation. Can be captured as a deposit.
The groove bottom 41a of the first air vent groove 41 has high water repellency due to its texture, and the captured deposits are easily peeled off by the circulating gas flow, so that accumulation of deposits in the first air vent groove 41 is suppressed. That is, the deposit attachment position becomes the depression of the dimple DP formed in the groove bottom 41a, and the first air vent groove 41 formed with a small groove depth (groove depth D1 is 0.003 to 0.01 mm) is completely It never gets blocked.

"Example"
FIG. 7 is a schematic plan view showing the first air vent groove 41 according to Example 1, FIG. 8 is a schematic plan view showing the first air vent groove 41 according to Example 2, and FIG. 9 is a schematic plan view showing the first air vent groove 41 according to Example 2. FIG. 10 is a perspective view showing the surface state of the first air vent groove 41 according to Example 1 after 2000 moldings, and FIG. 11 is a perspective view of the first air vent groove 41 according to Example 2 after 2000 moldings. FIG. 12 is a diagram showing the surface state of the groove bottom 41a, and FIG. 12 is a diagram showing the surface state of the first air vent groove 410 of the comparative example in which no texture is formed after 2000 moldings.

(Example 1)
A first air vent groove 41 having a group of dimples was formed on one surface of the air vent insert 14, and the air vent insert 14 was assembled into the injection mold 1 shown in FIG. As shown in FIG. 7, the first air vent groove 41 is formed as a concave groove with a groove width W1 of 1.5 mm, a groove depth D1 of 0.003 mm, and a groove length (land length) L1 of 1.3 mm. The groove bottom 41a has a texture consisting of a group of dimples in which dimples DP each having a diameter d of 0.011 mm and a depth t1 of 0.003 mm are arranged at a lattice angle of 60 degrees with respect to the gas flow direction (see Fig. 7). (shown as a ×1000 image) was formed.

Example 2
A first air vent groove 41 having a texture formed of grooves with a nano-periodic structure was formed on one surface of the air vent insert 14, and was incorporated into the injection molding die 1 shown in Fig. 1. As shown in Fig. 8, the first air vent groove 41 was formed as a concave groove with a groove width W1 of 1.5 mm, a groove depth D1 of 0.003 mm, and a groove length (land length) L1 of 1.3 mm, and a texture (shown in a ×1000 image taken by a metallurgical microscope in Fig. 8) in which vertical grooves GR having a width w of 0.0005 mm to 0.02 mm and a depth t2 of 0.005 mm to 0.05 mm were repeated at a nano-pitch p in the width direction of the groove bottom 41a.

As shown in FIG. 9, the gate 19 is used as a side gate, the first air vent groove 41 is disposed at a position opposite to the gate 19 on the opposite side of the gate 19, and PPS (polyphenylene sulfide) is used as the resin material. Then, a box-shaped molded product with length and width of 25 mm, height of 15 mm, and wall thickness of 2 mm was injection molded.

Using such an injection molding die 1, injection molding was performed 2000 times, and the adhesion of deposits to the groove bottom 41a of the first air vent groove 41 was observed. FIG. 10 shows an image of the first air vent groove 41 according to Example 1 after injection molding was performed 2000 times at a magnification of 400 times using a metallurgical microscope.
According to this, no deposit was observed on the upstream side (A in FIG. 10) of the first air vent groove 41 in the gas flow direction, where deposits tend to adhere. Furthermore, no deposits were observed in the downstream portion facing the second air vent groove 42 (B in FIG. 10).

Similarly, FIG. 11 shows an image of the first air vent groove 41 according to Example 2 after injection molding was performed 2000 times at a magnification of 400 times using a metallurgical microscope.
According to this, a small amount of deposit was observed on the upstream side in the gas flow direction of the first air vent groove 41 (A in FIG. 11) where deposits tend to adhere, but compared to the comparative example described below, The results showed that there was less deposit adhesion and accumulation. Furthermore, no deposits were observed in the central and downstream portions facing the second air vent groove 42 (B in FIG. 11).

On the other hand, in the first air vent groove 410 of the comparative example formed as a recessed groove with a groove width W1 of 1.5 mm, a groove depth D1 of 0.003 mm, and a groove length (land length) L1 of 1.3 mm, as shown in FIG. 12, adhesion and accumulation of deposits was observed on the upstream side (A in FIG. 12) of the first air vent groove 410 in the gas flow direction. However, no adhesion of deposits was observed in the downstream portion (B in FIG. 12) facing the second air vent groove 42.

In this embodiment, the second air vent groove 42 is a concave groove with a groove width W2 of 1 mm to 20 mm and a groove depth D2 of 1 mm to 2 mm deeper than the groove depth D1 of the first air vent groove 41. The second air vent groove 42 is formed in the air vent nest 14, following the first air vent groove 41, and facing the first air vent groove 41. The grooves 41 may be formed to communicate at a second groove depth D2 that is deeper than the groove depth D1.

1... Injection mold 10... Fixed side mold 11... Fixed side mounting plate, 12... Fixed side mold plate, 13... Fixed side nest, 14... Air vent nest, 15 ... Locate ring 20... Movable side mold, 24... Movable side template, 25... Core, 26... Movable side nest 30... Ejector mechanism 40... Air vent groove 41, 410 ...First air vent groove, 42...Second air vent groove 50...Annular air vent groove 60...Gas escape hole PL...Parting surface C...Cavity

Claims (8)

A mold for molding by injecting a molten resin material into a cavity formed by bringing a fixed mold and a movable mold into contact at their parting surfaces,
A texture is formed on the parting surface of at least one of the fixed mold and the movable mold to reduce surface energy, and a groove is connected to an end of the cavity at a first groove depth to allow gas in the cavity to flow. a second air vent groove, one end of which communicates with the first air vent groove at a second groove depth that is deeper than the first groove depth, and the other end of which communicates with the outside of the mold. Ta,
An injection mold characterized by: the texture is composed of a dimple group consisting of a plurality of dimples formed on the bottom of the first air vent groove;
2. The injection mold according to claim 1 . The dimple has a dimple depth that is the same as the first groove depth.
The injection mold according to claim 2, characterized in that: The dimple group is formed by a plurality of dimples arranged at a lattice angle of 30 degrees to 75 degrees,
The injection mold according to claim 3, characterized in that: The texture is composed of grooves with a nano periodic structure formed at the bottom of the first air vent groove.
The injection mold according to claim 1, characterized in that: The texture is formed by removing material at the bottom of the first air vent groove by irradiating with an ultra-short pulse laser.
The injection mold according to claim 1, characterized in that: The first air vent groove has a groove width of 1.0 mm or more and 2.0 mm or less, and a first groove depth of 0.003 mm to 0.01 mm.
The injection mold according to any one of claims 1 to 6, characterized in that: The molten resin material is a thermoplastic crystalline resin.
7. The injection mold according to claim 1, wherein the mold is a mold for injection molding.

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