JP2005225048A - Injection molding mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding mold capable of cooling a molded product to a thermal deformation temperature or below capable of taking out the molded product in its molding operation process while faithfully transferring and molding a highly detailed pattern, capable of sharply shortening a molding process time and capable of sharply enhancing productivity. <P>SOLUTION: The injection molding mold is equipped with a mold body 2 having a recessed part and the core block 4 fitted and held in the recessed part in a freely slidable manner to form a cavity 5 in the recessed part and constituted so that the core block 4 is heated to the glass transition point of a resin to be molded or above to compression-mold the resin charged in the cavity 5. The injection molding mold is also equipped with a cooling block 6 independently arranged to the end surface on the side opposite to the cavity side of the core block 4 so as to be brought into contact with and separated from the end surface and a drive means 7 for driving the cooling block 6 so as to bring in the direction brought into contact with and separated from the core block 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an injection mold for high-precision injection molding of optical components such as a double-sided prism sheet used as a key device for stereoscopic display liquid crystal such as an encoder resin disk and a mobile phone.

  Applying an injection mold to mold optical parts with fine patterns such as diffraction gratings and Fresnel lenses on the surface with a resin material with high accuracy, with the mold temperature heated above the glass transition point of the resin A method of performing injection molding or injection compression molding by filling a mold into a mold is already known. However, in such an injection mold, in order to take out the molded product from the mold, it is necessary to cool the resin filled in the mold until the temperature becomes lower than the heat deformation temperature, and the time required for the cooling is long. There was a problem that productivity was bad. In order to solve this problem, the cavity is formed in the process of heating the resin base material to a temperature higher than the glass transition temperature by using the PVT (pressure, specific volume, temperature) characteristics of the resin and then gradually cooling it to the heat deformation temperature or lower. An injection mold that is configured to be reduced from a state expanded to a final shape to a final shape is already known (see, for example, Patent Document 1).

  According to the conventional injection mold disclosed in Patent Document 1, by enlarging the cavity, the glass transition temperature is lowered together with the pressure of the resin base material, and the time required to equalize the internal pressure by heating this is reduced. The cavity is reduced to the final shape until the resin base material is solidified, and a resin product with high shape accuracy and uniform internal density is formed into the final shape. Because it is low, it is shortened.

JP-A-9-38994 (2nd page, FIG. 1)

  Since the conventional injection mold is configured as described above, the resin base material molded into a substantially final shape in advance and introduced into the cavity is heated above the glass transition point and then gradually lowered to the heat deformation temperature or lower. Since the mold temperature cannot be cooled below the thermal deformation temperature of the resin base material while heating the resin base material to the glass transition point or higher, it must be cooled. As a result, there is a problem in that it takes time to cool down to the point of time, and as a result, there is a limit in shortening the molding process time, which causes a problem in terms of productivity improvement.

  The present invention has been made to solve the above-described problems. While faithfully transfer-molding a high-definition pattern, it is cooled to a temperature lower than the heat deformation temperature at which the molded product can be taken out during the molding operation. It is an object of the present invention to obtain an injection mold that can greatly reduce the molding process time and greatly improve the productivity.

  An injection mold according to the present invention includes a mold body having a recess, and a nested block that is slidably fitted and held in the recess and forms a cavity in the recess, and the insert block is a resin to be molded. In an injection mold in which the resin filled in the cavity is heated by the glass transition point of the insert block and compression-molded by the insert block, the resin is independently arranged so as to be able to come into contact with and separate from the end surface opposite to the cavity side of the insert block. And a driving means for driving the cooling block in the contact / separation direction with respect to the nesting block.

  According to this invention, since the insert block heated above the glass transition point of the resin is pressed and moved by the cooling block to compress and mold the resin in the cavity, the resin in the cavity is compressed by the insert block. At the same time, the nested block at the time of compression molding can be quickly and efficiently cooled by heat exchange with the cooling block, and for this reason, high-precision transfer of a fine pattern to the surface of the molded product by the nested block, It is possible to realize rapid cooling of the nested block by the cooling block, and to greatly reduce the molding process time and greatly contribute to productivity improvement.

Embodiment 1 FIG.
FIG. 1 is a sectional view showing an injection mold according to Embodiment 1 of the present invention.
An injection mold 1 shown in FIG. 1 has a concave shape in cross section, a mold body 2 that is installed and fixed with the open end side facing down, and a skirt that is assembled and fixed to the open end side of the mold body 2 A mold 3, a nesting block 4 that is slidably fitted in a recess of the mold body 2 and forms a cavity 5 in the mold body 2, and a nesting block that is fitted in the mold 3 4 is a movable cooling block 6 that is arranged independently on the end surface opposite to the cavity 5 side so as to be able to contact and separate, and driving means for driving the cooling block 6 in the contact and separation direction with respect to the nesting block 4 (for example, This is a hydraulic cylinder (hereinafter also referred to as a hydraulic cylinder) 7.

  More specifically, the mold body 2 has a pattern forming surface 2a having a concave and convex surface shape of a continuous arc formed on a surface facing the insert block 4, and the insert block 4 The mold body 2 has an uneven surface-shaped pattern forming surface 4a forming a continuous V-groove formed on the surface facing the pattern forming surface 2a. Further, a flange 4b is formed integrally with the peripheral edge on the upper end side of the insert block 4, and the outer peripheral surface of the flange 4b is in sliding contact with the inner peripheral surface of the mold body 2. Here, an inner step portion 3 a is formed at the open end portion of the mold body 2 by an end face of the mold 3 attached to the mold body 2, and the flange portion of the nested block 4 is formed on the inner step portion 3 a. By engaging 4b, the nesting block 4 is prevented from coming out of the mold body 2.

  Each of the mold body 2 and the insert block 4 has a structure in which heaters 8 and 9 are embedded as heating means capable of temperature control. Further, the cooling block 6 includes a cooling pipe 10 embedded as a cooling passage for flowing a cooling medium such as water, and a plurality of heat insulating layers (heat insulating spaces) 11 provided in parallel below the cooling pipe 10. It has a structure. Here, each of the heaters 8 and 9 is connected to a temperature control means (not shown). This temperature control means turns on the power of the heater 9 of the nesting block 4 when the nesting block 4 and the cooling block 6 are separated from each other, and when the nesting block 4 is pushed and moved by the cooling block 6 (extension operation of the hydraulic cylinder 7). The heater power is turned on / off so that the power of the heater 9 is turned off.

  In the injection mold 1 configured as described above, between the inner wall surface of the mold 3 and the barrel peripheral wall surface of the nesting block 4, between the inner wall surface of the mold frame 3 and the peripheral wall surface of the cooling block 6. Is provided with a heat insulating layer (heat insulating space) 12, and after the resin molding in which the flange portion 4b of the nested block 4 is in contact with and supported by the inner step portion 3a on the mold body 2 open end side, the nested block The cooling block 6 descends and separates from 4, and a heat insulating layer (heat insulating space) 12a is also provided between the opposing surfaces.

Next, the operation will be described.
Prior to resin molding, as shown in FIG. 1, the insert block 4 is held in a lowered position in which the flange portion 4b is engaged and supported on the inner step portion 3a of the injection mold 1 and the cooling block 6 is It is held in a lowered position separated from the nesting block 4. In this state, the mold body 2 is heated below the glass transition point, the nested block 4 is heated to a set temperature above the glass transition point of the resin by the heaters 8 and 9, and the cooling pipe 10 of the cooling block 6 is cooled. The medium is supplied and circulated. In this state, when the resin is filled into the cavity 5 of the mold body 2 from an injection molding machine (not shown) and the hydraulic cylinder 7 is operated (extension operation) after the filling, the cooling block 6 causes the nesting block 4 to move. The resin in the cavity 5 is pressure-molded by pressing and raising the nesting block 4. Simultaneously with the pressurization, the power supply to the heater 9 of the nested block 4 is cut off, so that the temperature rise of the nested block 4 is suppressed. Since the cooling block 6 is in contact with the nesting block 4 at this time, heat exchange between the two is performed quickly and efficiently, and the temperature of the nesting block 4 is lowered. Thereby, the mold 1 is opened at the stage where the nesting block 4 is lowered to the heat deformation temperature or lower, and the resin molded product is taken out. After the removal, the hydraulic cylinder 7 is shortened to lower the cooling block 6 and the nesting block 4, thereby separating the nesting block 4 and the cooling block 6 as shown in FIG. After the separation, when the heater 9 of the nesting block 4 is turned on, the temperature of the nesting block is again raised to the glass transition point or more, and the above-described resin molding is repeated.

  According to the first embodiment described above, high-definition pattern molding surfaces 2a and 4a having different shapes are formed on opposing surfaces sandwiching the cavity 5 of the mold body 2 and the nesting block 4, and the nesting block 4 is made of resin. Since the resin is filled in the cavity 5 by heating above the glass transition point, the nesting block 4 is pressed and moved by the cooling block 6, and the resin is compression molded by the nesting block 4. A high-definition pattern can be faithfully transferred to the surface of the molded product by the pattern molding surfaces 2a and 4a. In particular, simultaneously with the compression molding of the resin that is the molded product material, the nested block 4 and the cooling block 6 The heat can be rapidly cooled to below the heat distortion temperature at which the molded product can be removed by heat exchange. There is an effect that can be greatly reduced. In addition, when resin compression is started by the nesting block 4, that is, when the nesting block 4 is pressed by the cooling block 6, the power source of the heater 9 of the nesting block 4 is cut off. The exchange efficiency is further improved, the rapid cooling of the nesting block 4 can be realized, and the molding process time until the molded product is taken out can be further greatly shortened.

  Further, according to the first embodiment, the cooling block 6 is separated from the nesting block 4 when the resin is filled into the cavity 5, and the heat insulating layer 12a is formed between them, so that the nesting block 6 is made of resin glass. There is an effect that it can be maintained in a heated state above the transition point. Furthermore, since the heat insulating layer 12 is also formed between the periphery of the nesting block 4 and the cooling block 6 and the mold 3, the nesting block 4 heated to a high temperature and the low-temperature cooling block 6 are formed in the same mold. In addition, when the resin is compressed by the nesting block 4, only the nesting block 4 and the cooling block 6 are in contact with each other, so that the heat exchange efficiency between them is improved, and the nesting block 4 can be quickly and rapidly cooled. There is an effect that it can be realized more reliably.

Example 1.
Next, an experimental result in which a fine pattern of continuous V-grooves and continuous arcs is formed on both surfaces of a sheet-like resin having a width of 35 mm, a length of 43 mm, and a thickness of 0.25 mm by the injection mold 1 according to the first embodiment. explain.
In the first embodiment, the pattern forming surface (continuous arc surface) 2a of the mold body 2 is continuously formed in parallel with the long side at R90 μm and pitch 90 μm, and the pattern forming surface (continuous V groove) of the nesting block 4 is formed. 4a was continuously formed with a height of 77 μm, apex angle of 60 °, and a pitch of 90 μm parallel to the long side. Further, as the resin filled in the cavity 5, a product name TOPAS5013 (Polyplastic Co., Ltd.), a cyclic polyolefin polymer, was used. The mold body 2 was heated to 135 ° C. lower than the glass transition point of the resin, and the nested block 4 was heated to 150 ° C. higher than the glass transition point of the resin by the respective heaters 8 and 9. Further, water at 30 ° C. was supplied and circulated as a cooling medium to the cooling pipe 10 of the cooling block 6. In this state, the resin was filled into the cavity 5 of the mold body 2 from the injection molding machine. The resin temperature at this time was set to 300 ° C. After filling the resin, the resin in the cavity 5 was pressurized by pressing the cooling block 6 with the hydraulic cylinder 7 and bringing it into contact with the nesting block 4 as shown in FIG. Simultaneously with the pressurization, the power source of the heater 9 of the nesting block 4 was shut off. As a result, the temperature rise of the nested block 4 is suppressed, and heat exchange between the nested block 4 and the cooling block 6 is performed, so that the temperature of the nested block 4 is the same as the glass transition point of the mold body 2. The temperature could be lowered to the following 135 ° C. Therefore, the mold 1 was opened and the resin molded product was taken out. After the removal, the cooling block 6 and the nesting block 4 were moved backward to separate the nesting block 4 and the cooling block 6. Subsequently, the heater 9 of the nesting block 4 was turned on, the temperature of the nesting block 4 was raised to 150 ° C., the resin was filled in the cavity 5 again, and the same process as described above was performed.

  According to the first embodiment described above, the resin in the cavity 5 is compressed by the nesting block 4 through the cooling block 6, and the continuous V groove and the continuous arc are formed on both surfaces of the ultrathin molded product having a thickness of 0.25mm. Was transferred faithfully, and further, the nested block 4 was rapidly quenched by contact with the cooling block 6, and a highly accurate molded product could be obtained in a short time.

Embodiment 2. FIG.
3 is a cross-sectional view showing an injection mold according to Embodiment 2 of the present invention, and FIG. 4 is a cross-sectional view showing the operation state of FIG. 3. The same parts as those in FIGS. Therefore, duplicate explanation is omitted.
In the second embodiment, the pattern forming surface (continuous arc surface) 2a of the mold body 2 according to the first embodiment is eliminated, and the surface facing the pattern forming surface (continuous V groove) 4a of the nesting block 4 is a flat surface. It is what. Therefore, according to the second embodiment, the same effects as those of the first embodiment can be obtained except for the effect of the pattern forming surface 2a of the mold body 2 of the first embodiment.

Example 2
Next, an experimental result in which a continuous V-groove fine pattern is formed on one side of a sheet-like resin having a width of 35 mm, a length of 43 mm, and a thickness of 0.4 mm by the injection mold 1 according to the second embodiment will be described. .
In Example 2, the continuous V groove on the pattern forming surface 4a of the nesting block 4 was continuously formed parallel to the long side at a height of 130 μm, an apex angle of 60 °, and a pitch of 150 μm. Moreover, as resin filled in the cavity 5, the product name ZEONOR (Nippon Zeon Co., Ltd.) of cyclic polyolefin-type polymer resin was used. The mold body 2 was heated to 135 ° C. lower than the glass transition point of the resin, and the nested block 4 was heated to 145 ° C. higher than the glass transition point of the resin by the respective heaters 8 and 9. Further, water at 30 ° C. was supplied and circulated as a cooling medium to the cooling pipe 10 of the cooling block 6.

  In this state, the resin was filled into the cavity 5 of the mold body 2 from the injection molding machine. The resin temperature at this time was set to 300 ° C. After filling the resin, the resin in the cavity 5 was pressurized by pressing the cooling block 6 with the hydraulic cylinder 7 to contact the nesting block 4 and raising the nesting block 4 as shown in FIG. Simultaneously with the pressurization, the power source of the heater 9 of the nesting block 4 was shut off. As a result, the temperature rise of the nested block 4 is suppressed, and heat exchange between the nested block 4 and the cooling block 6 is performed, so that the temperature of the nested block 4 is the same as the glass transition point of the mold body 2. The temperature could be lowered to the following 135 ° C. Therefore, the mold 1 was opened and the resin molded product was taken out. After the removal, the cooling block 6 and the nesting block 4 were moved backward to separate the nesting block 4 and the cooling block 6. Next, the heater 9 of the nesting block 4 was turned on, the temperature of the nesting block 4 was raised to 145 ° C., the cavity 5 was filled again with resin, and the same process as described above was performed.

  According to the second embodiment described above, the resin in the cavity 5 is compressed by the nesting block 4 through the cooling block 6, and the continuous V-groove is faithfully formed on one surface of the ultra-thin molded product having a thickness of 0.4 mm. Then, the nest block 4 was rapidly cooled by contact with the cooling block 6, and a highly accurate molded product could be obtained in a short time.

Example 3
Next, an experimental result of forming a continuous V-groove fine pattern on one side of a sheet-like resin having a diameter of 26 mm and a thickness of 1.3 mm by the injection mold 1 according to the second embodiment. explain.
In Example 2, the pattern forming surface 4a of the nesting block 4 was formed with V grooves having a height of 1 to 20 μm in the radial direction, a vertex angle of 90 ° and a pitch of 2 to 40 μm in the circumferential direction. Further, as the resin filled in the cavity 5, polycarbonate resin product name Iupilon H4000 (Mitsubishi Engineering Plastics) was used. The mold body 2 was heated by the heaters 8 and 9 to 145 ° C. lower than the glass transition point of the resin, and the nested block 4 was heated to 155 ° C. higher than the glass transition point of the resin. Further, water at 30 ° C. was supplied and circulated as a cooling medium to the cooling pipe 10 of the cooling block 6.

  In this state, the resin was filled into the cavity 5 of the mold body 2 from the injection molding machine. The resin temperature at this time was set to 300 ° C. After filling the resin, the resin in the cavity 5 was pressurized by pressing the cooling block 6 with the hydraulic cylinder 7 and bringing it into contact with the nesting block 4 and raising the nesting block 4 in the same manner as in Example 1 above. Simultaneously with the pressurization, the power source of the heater 9 of the nesting block 4 was shut off. As a result, the temperature rise of the nested block 4 is suppressed, and heat exchange between the nested block 4 and the cooling block 6 is performed, so that the temperature of the nested block 4 is the same as the glass transition point of the mold body 2. The temperature could be lowered to the following 145 ° C. Therefore, the mold 1 was opened and the resin molded product was taken out. After the removal, the cooling block 6 and the nesting block 4 were moved backward to separate the nesting block 4 and the cooling block 6. Next, the heater 9 of the nesting block 4 was turned on, the temperature of the nesting block 4 was raised to 155 ° C., the cavity 5 was filled with resin again, and the same process as described above was performed.

  According to the third embodiment described above, the resin in the cavity 5 is compressed by the nesting block 4 through the cooling block 6, and the continuous V-groove is faithfully formed on one surface of the ultra-thin molded product having a thickness of 0.4 mm. Then, the nest block 4 was rapidly cooled by contact with the cooling block 6, and a highly accurate molded product could be obtained in a short time.

It is sectional drawing which shows the injection mold by Embodiment 1 of this invention. It is sectional drawing which shows the operation state of FIG. It is sectional drawing which shows the injection mold by Embodiment 2 of this invention. It is sectional drawing which shows the operation state of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Injection mold 2 Mold body 2a Pattern molding surface 3 Mold frame 3a Inner step part 4 Nest block 4a Pattern molding surface 4b Eaves part 5 Cavity 6 Cooling block 7 Driving means 8 , 9 Heater (heating means), 10 Cooling pipe (cooling means), 11, 12, 12a Heat insulation layer.

Claims (4)

  A mold body having a recess, and a nesting block that is slidably fitted and held in the recess to form a cavity in the recess, and the nesting block is heated to a temperature above the glass transition point of the molding resin, In an injection mold for compressing and molding a resin filled in a cavity with the insert block, a cooling block that is arranged independently on and away from the end surface of the insert block opposite to the cavity side, and this cooling block An injection mold characterized by comprising a driving means for driving in the direction of contact with and away from the insert block.   2. The injection mold according to claim 1, wherein at least one of the opposing surfaces of the mold body and the insert block facing each other with the cavity interposed therebetween is formed as a pattern forming surface having a continuous uneven surface shape.   A skirt-shaped mold is attached to the open end of the mold body, and a heat insulating layer is provided between the inner peripheral wall surface of the mold and the nesting block and the cooling block. 3. An injection mold according to claim 1 or claim 2.   The heating means is embedded in the nesting block, and the heating means is connected to temperature control means for stopping heating of the nesting block when the nesting block is pressed and moved by the cooling block. The injection mold according to claim 3.

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