JP4415703B2 - Mold cleaning method and apparatus, molding method and apparatus - Google Patents

Description

  The present invention relates to a mold cleaning method and apparatus and a highly accurate molding method and apparatus.

  Molds used for molding plastics, rubbers, and the like have had a situation where residues such as plastics, rubbers or additives added thereto accumulate when used for a long period of time, and good molding cannot be performed. In order to remove such residues and the like, the mold is usually washed after being used for a predetermined period.

  As a method of performing the above-described cleaning, there is a method of wiping with a waste soaked with an organic solvent or water.

  Further, there is a method in which the mold is heated to about 130 ° C. and then washed with a strong alkaline cleaner on the mold. Alternatively, a method of using a mold cleaner in which a polyhydric alcohol that does not denature at 130 to 150 ° C. is added as a main component, a strong alkali is added thereto, and a surfactant that is not denatured at 130 to 150 ° C. is added is also proposed. (For example, refer to Patent Document 1).

  In addition, in resin molds such as ICs, fine resin molding resin remains after releasing the lead frame, which adversely affects the subsequent molding, so a jet of small glass beads is sprayed onto the resin mold. It was supposed to be washed (dry blasting method). Alternatively, a method has been proposed in which a mold for resin molding is arranged in a cleaning section with a fixing jig, and the mold is cleaned by spraying a water jet from a nozzle onto the fixed mold (for example, Patent Documents). 2).

  In addition, as a cleaning method for removing dust, foreign matter, etc. attached to the surface of a precision mold such as a stamper for optical disc manufacturing, the final cleaning process is performed after cleaning the mold in purified water in an ultrasonic cleaning tank. Is performed by steam cleaning (see, for example, Patent Document 3). Alternatively, there is also proposed a mold cleaning method having a first step of forming a metal layer made of a material different from the material of the mold on the surface of the mold to be cleaned and a second step of removing the metal layer. (For example, see Patent Document 4).

In addition to the above-mentioned molds that have been known for a long time, excellent cleaning of molds for optical devices that need to transfer fine structures with high accuracy, such as backlight light guide plates and diffraction gratings for liquid crystal displays. Although technology is required, the present situation is that cleaning is performed by appropriately combining various cleaning methods as described above.
JP-A-11-90938 Japanese Patent Laid-Open No. 10-15556 JP-A-4-205737 JP 7-34274 A

  However, the conventional cleaning has various problems.

  In the wiping method, since the waste does not sufficiently reach every corner of the fine recess on the mold surface, there is a problem in that the deposits that enter the interior of the recess cannot be removed.

  The method of applying the mold cleaning agent to the mold has the disadvantage that it takes 3 to 5 days to complete the cleaning of the mold, and the disadvantage that the fine portions such as the grooves cannot be sufficiently removed.

  Further, in cleaning with glass beads, since glass beads are sprayed like sandblast or shot blast, the precision molding surface of the mold is heavily worn and dust is generated, which adversely affects the working environment. Furthermore, there is a problem that the running cost and the disposal cost for blasting are large.

  Also, in the method of cleaning the mold by ultrasonic cleaning, bubbles (cavitation) generated by the ultrasonic wave are larger than the fine recesses on the mold surface, so that they do not reach all the corners of the fine recesses sufficiently. There was a problem that the deposits that entered the back of the recess could not be removed. In addition, since the fine particles floating near the mold surface vibrate vigorously due to the high energy of the ultrasonic wave, there is a problem that they may hit and damage the mold surface.

  Further, in the cleaning method using a surfactant and water jet and ultrasonic cleaning, since it is a wet process, waste liquid treatment is required, and there is a problem that the burden on cost and environment is large.

  Further, in a mold cleaning method comprising a first step of forming a metal layer of a material different from the material of the mold on the surface of the mold to be cleaned, and a second step of removing the metal layer. However, there is a problem in that the mold maintenance is complicated because an additional process with a large cost burden of forming and removing the metal layer is required.

  In addition, the conventional method has an effect of removing physical dirt from the mold, but has a problem that frequent cleaning is required because the effect of removing chemical dirt is small.

  In view of the above-described conventional problems, the present invention provides a method and apparatus for cleaning a mold easily in a short time, and a molding method and apparatus having a large maintenance cycle. It is intended to provide.

  The mold cleaning method of the first invention of the present application is characterized in that the molding surface of the mold is cleaned by irradiating the molding surface of the mold with atmospheric pressure plasma.

  With such a configuration, the cleaning cycle is large, the life of the mold can be extended, and the mold can be easily cleaned in a short time.

  In the mold cleaning method of the second invention of the present application, an electrode having a gas ejection port is brought close to the molding surface of the mold, and gas is blown from the gas ejection port toward the molding surface at a pressure near atmospheric pressure. By applying a voltage between the mold and the electrode, plasma is generated between the mold and the electrode to clean the molding surface of the mold.

  With such a configuration, the cleaning cycle is large, the life of the mold can be extended, and the mold can be easily cleaned in a short time.

  In the mold cleaning method of the second invention of the present application, it is preferable that the distance between the mold and the electrode is 0.5 mm or more and 2 mm or less. More preferably, the distance between the mold and the electrode is 1 mm or more and 1.5 mm or less.

  Preferably, the surface of the electrode facing the molding surface is covered with a dielectric having a gas outlet, and in this case, preferably the gas outlet provided in the dielectric is preferably It is desirable that the inner diameter is smaller than the inner diameter of the gas outlet provided in the electrode. In this case, preferably, the inner diameter of the gas outlet provided in the dielectric is 0.1 mm to 0.5 mm, and the inner diameter of the gas outlet provided in the electrode is greater than 0.5 mm and 2 mm or less. It is desirable to be.

  In the mold cleaning method of the third invention of the present application, a gas is supplied between a pair of electrodes at a pressure near atmospheric pressure, and a plasma is generated by applying a voltage between the pair of electrodes. The molding surface of the mold is cleaned by spraying the active particles generated in (1) from the gas outlet toward the molding surface of the mold.

  With such a configuration, the cleaning cycle is large, the life of the mold can be extended, and the mold can be easily cleaned in a short time.

  According to a fourth aspect of the present invention, there is provided a mold cleaning apparatus comprising: an electrode having a gas outlet; a gas supply device that supplies gas to the electrode; a cradle for mounting the mold; and the mold, the cradle, or the electrode. And a power supply for applying a voltage, wherein the gas outlet and the cradle face each other.

  With such a configuration, the cleaning cycle is large, the life of the mold can be extended, and the mold can be easily cleaned in a short time.

  In the mold cleaning apparatus according to the fourth aspect of the present invention, it is preferable that the distance between the mold and the electrode is 0.5 mm or more and 2 mm or less. More preferably, the distance between the mold and the electrode is 1 mm or more and 1.5 mm or less.

  Preferably, the surface of the electrode facing the molding surface is covered with a dielectric having a gas outlet, and in this case, preferably the gas outlet provided in the dielectric is preferably It is desirable that the inner diameter is smaller than the inner diameter of the gas outlet provided in the electrode. In this case, preferably, the inner diameter of the gas outlet provided in the dielectric is 0.1 mm to 0.5 mm, and the inner diameter of the gas outlet provided in the electrode is greater than 0.5 mm and 2 mm or less. It is desirable to be.

  The mold cleaning device according to the fifth aspect of the present invention is configured to apply a voltage between a pair of electrodes, a gas supply device that supplies gas between the pair of electrodes, a cradle for mounting the mold, and a pair of electrodes. And a gas jet port provided downstream of the pair of electrodes, and the gas jet port and the cradle are opposed to each other.

  With such a configuration, the cleaning cycle is large, the life of the mold can be extended, and the mold can be easily cleaned in a short time.

  A molding method according to a sixth invention of the present application includes a step of filling a molding material between a pair of molds, a step of molding the molding material by applying heat and pressure to the mold, and a step of taking out the molded molding material And a step of irradiating the molding surface of the mold with atmospheric pressure plasma.

  With such a configuration, a molding method having a large maintenance cycle can be realized.

  A molding apparatus according to a seventh invention of the present application includes a filling unit that fills a molding material between a pair of molds, a molding unit that molds by applying heat and pressure to the mold, and a takeout unit that takes out the molded molding material And a cleaning unit that irradiates the molding surface of the mold with atmospheric pressure plasma.

  With such a configuration, a molding apparatus having a large maintenance cycle can be realized.

  As described above, according to the mold cleaning method and apparatus, the molding method and apparatus, the cleaning cycle is large, the life of the mold can be extended, and the mold and cleaning method can be easily performed in a short time. It is possible to provide a molding method and apparatus having a large maintenance cycle.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
Hereinafter, a first embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a cross-sectional view showing a configuration of a mold cleaning apparatus according to a first embodiment of the present invention. In FIG. 1, a mold 2 is placed on a cradle 1. An electrode 4 having a gas ejection port 3 is provided to face the cradle 1. Gas is supplied from a gas supply device 7 to a gas flow path 6 provided in the electrode 4 and communicating with the gas outlet 3 at a pressure close to the atmospheric pressure with the electrode 4 placed close to the molding surface 5 of the mold 2. Then, gas is blown from the gas outlet 3 toward the molding surface 5. The electrode 4 is grounded. By applying a high frequency voltage from the power source 8 to the cradle 1, an electric field is generated between the mold 2 and the electrode 4, and plasma 9 is generated between the mold 2 and the electrode 4. The active particles generated in the plasma 9 react with the dirt on the molding surface, and the dirt is removed and cleaned.

  On the condition that helium / argon / oxygen = 860/140/10 sccm is flowed as a gas to the mold after molding, and high frequency power = 40 W at a frequency of 13.56 MHz is applied to the cradle 1 in an atmospheric pressure atmosphere. When processed, cleaning was completed in about 30 seconds.

  In the method of performing molding using a mold that has been cleaned by this method, a non-defective product rate of 95% or more was obtained by cleaning once to several days. In the conventional wiping method, it can be seen that the cleaning cycle has been dramatically increased by the present invention, considering that it has been necessary to perform cleaning several to ten times a day. In addition, in the past, it took several minutes for manual wiping, and in the method of applying the mold cleaning agent to the mold, it took 3 to 5 days to complete the mold cleaning. Cleaning can be performed in an extremely short time.

  In addition, the wiping method caused slight wear of the mold, and the mold had to be discarded after use for 3 to 5 days. However, according to this cleaning method, it was used continuously for 10 days or more. This has made it possible to extend the tool life. Further, the active particles sufficiently acted to every corner of the fine unevenness of the mold, and good cleaning could be performed.

  In addition, in the cleaning with glass beads, the wear of the precise molding surface of the mold was intense, but according to the cleaning method of this time, the metal mold is hardly etched by oxygen radicals, so the molding surface is cleaned before and after cleaning. The shape and dimensions were almost unchanged. Moreover, no dust was generated and the work environment was not contaminated. Furthermore, since only a gaseous thing is generated as a waste, a disposal cost is unnecessary.

  The reason for the improvement as described above is considered to be because the active particles that are chemically active and have almost no physical damage are acted on the molding surface, such as atmospheric pressure plasma. That is, chemical stains (oxides, carbides, etc.) that could not be removed by the wiping method could be removed by oxygen radicals in the plasma. This is considered to have contributed to the improvement of the cleaning cycle.

  In vacuum plasma, high-energy ions of 10 to 100 eV collide with the molding surface and the molding surface is roughened or deformed by sputtering, whereas in atmospheric pressure plasma, the energy of ions colliding with the molding surface is 0.1 to It is about 5 eV, and almost no roughening or deformation occurs.

  In the above example, the case where a high frequency voltage is applied to the cradle 1 and the electrode 4 is grounded is illustrated, but conversely, the cradle 1 may be grounded by applying a voltage to the electrode 4. Alternatively, the cradle may be an insulator, and a contact for contacting the mold may be provided inside the cradle, and a voltage may be applied to the cradle or grounded. Further, in addition to the high-frequency voltage, a pulse voltage in the kHz range may be alternately supplied. When using a high-frequency voltage, it is preferable to use a gas mainly composed of helium in order to generate an atmospheric pressure plasma while avoiding arc discharge.

  Further, in the case of using a pulse voltage, it is possible to perform processing with inexpensive compressed air or nitrogen gas without using a rare gas such as helium or argon.

(Embodiment 2)
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS.

  FIG. 2 is a cross-sectional view showing a configuration of a mold cleaning apparatus according to the second embodiment of the present invention. In FIG. 2, a mold 2 is placed on a cradle 1. An electrode 4 having a gas ejection port 3 is provided to face the cradle 1. Gas is supplied from a gas supply device 7 to a gas flow path 6 provided in the electrode 4 and communicating with the gas outlet 3 at a pressure close to the atmospheric pressure with the electrode 4 placed close to the molding surface 5 of the mold 2. Then, gas is blown from the gas outlet 3 toward the molding surface 5. The electrode 4 is grounded. By applying a high frequency voltage from the power source 8 to the cradle 1, an electric field is generated between the mold 2 and the electrode 4, and plasma 9 is generated between the mold 2 and the electrode 4. Active particles generated in the plasma 9 are jetted onto the molding surface, react with the dirt on the molding surface, and the dirt is removed and cleaned. The difference from the first embodiment of the present invention is that the surface of the electrode 4 facing the molding surface 5 is covered with a dielectric 11 having a gas ejection port 10.

  On the condition that helium / argon / oxygen = 860/140/10 sccm is flowed as a gas to the mold after molding, and high frequency power = 100 W at a frequency of 13.56 MHz is applied to the receiving base 1 in an atmospheric pressure atmosphere. When processed, cleaning was completed in about 10 seconds.

  In the method of performing molding using a mold that has been cleaned by this method, a non-defective product rate of 95% or more was obtained by cleaning once to several days. In the conventional wiping method, it can be seen that the cleaning cycle has been dramatically increased by the present invention, considering that it has been necessary to perform cleaning several to ten times a day. In addition, in the past, it took several minutes for manual wiping, and in the method of applying the mold cleaning agent to the mold, it took 3 to 5 days to complete the mold cleaning. Cleaning can be performed in an extremely short time.

  In addition, the wiping method caused slight wear of the mold, and the mold had to be discarded after use for 3 to 5 days. However, according to this cleaning method, it was used continuously for 10 days or more. This has made it possible to extend the tool life. Further, the active particles sufficiently acted to every corner of the fine unevenness of the mold, and good cleaning could be performed.

  In addition, in the cleaning with glass beads, the wear of the precise molding surface of the mold was intense, but according to the cleaning method of this time, the metal mold is hardly etched by oxygen radicals, so the molding surface is cleaned before and after cleaning. The shape and dimensions were almost unchanged. Moreover, no dust was generated and the work environment was not contaminated. Furthermore, since only a gaseous thing is generated as a waste, a disposal cost is unnecessary.

  The reason for the improvement as described above is considered to be because the active particles that are chemically active and have almost no physical damage are acted on the molding surface, such as atmospheric pressure plasma. That is, chemical stains (oxides, carbides, etc.) that could not be removed by the wiping method could be removed by oxygen radicals in the plasma. This is considered to have contributed to the improvement of the cleaning cycle.

  In vacuum plasma, high-energy ions of 10 to 100 eV collide with the molding surface and the molding surface is roughened or deformed by sputtering, whereas in atmospheric pressure plasma, the energy of ions colliding with the molding surface is 0.1 to It is about 5 eV, and almost no roughening or deformation occurs.

  In addition, the reason why the processing can be performed in a shorter time than the first embodiment of the present invention is that the surface of the electrode 4 that faces the molding surface 5 is covered with the dielectric 11 having the gas ejection port 10. This is because arc discharge (spark discharge) hardly occurs and a large amount of electric power can be applied. Furthermore, the inner diameter of the gas outlet 10 provided in the dielectric 11 is smaller than the inner diameter of the gas outlet 3 provided in the electrode 4. This is the reason why arc discharge is difficult to occur. Here, the inner diameter of the gas outlet 10 provided in the dielectric 11 is 0.2 mm, and the inner diameter of the gas outlet 3 provided in the electrode 4 is 1 mm, but the gas outlet 10 provided in the dielectric 11 is used. The inner diameter of the gas jet nozzle 3 provided on the electrode 4 is preferably larger than 0.5 mm and smaller than 2 mm. It is not preferable to make the inner diameter of the gas ejection port 10 provided in the dielectric 11 smaller than 0.2 mm because the processing cost increases and the discharge characteristics change due to wear. When the inner diameter of the gas outlet 10 provided in the dielectric 11 is larger than 1 mm, the effect of suppressing arc discharge is weakened. Moreover, when the inner diameter of the gas outlet 3 provided in the electrode 4 is 0.5 mm or less, arc discharge tends to occur, which is not preferable. If the inner diameter of the gas outlet 3 provided in the electrode 4 is 2 mm or more, the cleaning speed at the center of the molding surface 5 is lowered, which is not preferable.

  FIG. 3 shows the ashing speed between the lower surface of the electrode 4 and the central portion of the molding surface 5 when the silicon substrate on which a photoresist is formed instead of the mold 2 is ashed in the cleaning device shown in FIG. It depends on distance. The above example of cleaning for 10 seconds is the result when the distance between the electrode 4 and the center of the molding surface 5 of the mold 2 is 1 mm. If the distance between the electrode and the substrate is less than 0.5 mm, the ashing speed is remarkably small, and thus it is not suitable for practical use. It has been found that arc discharge is always observed when the distance between the electrode and the substrate is greater than 2 mm, and such a condition is not suitable for practical use. When the distance between the electrode and the substrate was 1 mm or more and 1.5 mm or less, high-speed processing could be performed, and arc discharge was not always observed. From the above results, it was found that the optimum distance is 1 mm or more and 1.5 mm or less, and in some cases, the treatment can be performed in the range of 0.5 mm or more and 2 mm or less. When the distance between the electrode and the substrate was greater than 1.5 mm and less than 2 mm, arc discharge occurred or did not occur (this is represented by a dotted line in the figure).

  In the above example, the case where a high frequency voltage is applied to the cradle 1 and the electrode 4 is grounded is illustrated, but conversely, the cradle 1 may be grounded by applying a voltage to the electrode 4. Alternatively, the cradle may be an insulator, and a contact for contacting the mold may be provided inside the cradle, and a voltage may be applied to the cradle or grounded. Further, in addition to the high-frequency voltage, a pulse voltage in the kHz range may be alternately supplied. When using a high-frequency voltage, it is preferable to use a gas mainly composed of helium in order to generate an atmospheric pressure plasma while avoiding arc discharge.

  Further, in the case of using a pulse voltage, it is possible to perform processing with inexpensive compressed air or nitrogen gas without using a rare gas such as helium or argon.

(Embodiment 3)
Hereinafter, a third embodiment of the present invention will be described with reference to FIG.

  FIG. 4 is a cross-sectional view showing a configuration of a mold cleaning apparatus according to a third embodiment of the present invention. In FIG. 4, the mold 2 is placed on the cradle 1. The inner electrode 12 and the outer electrode 13 are coaxially arranged to form a pair of electrodes. A gas is supplied from the gas supply device 7 to the gas flow path 6 between the inner electrode 12 and the outer electrode 13, and a high frequency voltage is applied to the inner electrode 12 from the power source 8. An electric field is generated, and plasma 9 is generated between the inner electrode 12 and the outer electrode 13. Cleaning the molding surface 5 of the mold 2 by spraying the active particles generated in the plasma 9 toward the molding surface 5 of the mold 2 from a gas outlet 3 arranged downstream of the pair of electrodes. Can do. The cradle 1 is grounded. Further, a cylindrical dielectric 11 is provided inside the outer electrode 13 to effectively prevent the occurrence of arc discharge.

  On the condition that helium / argon / oxygen = 860/140/10 sccm is flowed as a gas to the mold after molding, and high frequency power = 100 W at a frequency of 13.56 MHz is applied to the receiving base 1 in an atmospheric pressure atmosphere. When processed, cleaning was completed in about 8 seconds.

  In the method of performing molding using a mold that has been cleaned by this method, a non-defective product rate of 95% or more was obtained by cleaning once to several days. In the conventional wiping method, it can be seen that the cleaning cycle has been dramatically increased by the present invention, considering that it has been necessary to perform cleaning several to ten times a day. In addition, in the past, it took several minutes for manual wiping, and in the method of applying the mold cleaning agent to the mold, it took 3 to 5 days to complete the mold cleaning. Cleaning can be performed in an extremely short time.

  In addition, the wiping method caused slight wear of the mold, and the mold had to be discarded after use for 3 to 5 days. However, according to this cleaning method, it was used continuously for 10 days or more. This has made it possible to extend the tool life. Further, the active particles sufficiently acted to every corner of the fine unevenness of the mold, and good cleaning could be performed.

  In addition, in the cleaning with glass beads, the wear of the precise molding surface of the mold was intense, but according to the cleaning method of this time, the metal mold is hardly etched by oxygen radicals, so the molding surface is cleaned before and after cleaning. The shape and dimensions were almost unchanged. Moreover, no dust was generated and the work environment was not contaminated. Furthermore, since only a gaseous thing is generated as a waste, a disposal cost is unnecessary.

  The reason for the improvement as described above is considered to be because the active particles that are chemically active and have almost no physical damage are acted on the molding surface, such as atmospheric pressure plasma. That is, chemical stains (oxides, carbides, etc.) that could not be removed by the wiping method could be removed by oxygen radicals in the plasma. This is considered to have contributed to the improvement of the cleaning cycle.

  In vacuum plasma, high-energy ions of 10 to 100 eV collide with the molding surface and the molding surface is roughened or deformed by sputtering, whereas in atmospheric pressure plasma, the energy of ions colliding with the molding surface is 0.1 to It is about 5 eV, and almost no roughening or deformation occurs.

  Moreover, since the inner side of the outer electrode 13 is covered with the dielectric 11, the arc discharge (spark discharge) hardly occurs because the processing can be performed in a shorter time than the first and second embodiments of the present invention. It is considered that a large amount of electric power can be input and that the active oxygen having a higher concentration than that in the plasma 9 is caused to act on the die by arranging the die 2 downstream of the plasma 9. .

  In the above example, a case where a high frequency voltage is applied to the inner electrode 12 and the outer electrode 13 is grounded is illustrated, but conversely, a voltage may be applied to the outer electrode 13 and the inner electrode 12 may be grounded. However, in consideration of work safety, it is better to apply a high frequency voltage to the inner electrode 12 and ground the outer electrode 13. Further, in addition to the high-frequency voltage, a pulse voltage in the kHz range may be alternately supplied. When using a high-frequency voltage, it is preferable to use a gas mainly composed of helium in order to generate an atmospheric pressure plasma while avoiding arc discharge. Further, in the case of using a pulse voltage, it is possible to perform processing with inexpensive compressed air or nitrogen gas without using a rare gas such as helium or argon.

  Moreover, although the case where a pair of electrode was arrange | positioned coaxially was illustrated, you may arrange | position in a parallel plate shape. However, in consideration of in-plane uniformity of processing, it is better to arrange them coaxially.

(Embodiment 4)
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG.

  FIG. 5 is a perspective view showing the configuration of the molding apparatus 14 in the fourth embodiment of the present invention. The molding apparatus 14 shown in FIG. 5 conveys an unprocessed molding material case 15, a processed molding material case 16, a filling portion 17 for filling a molding material between a pair of molds, and a mold set filled with the molding material. A loader unit 18, a molding unit 19 for applying heat and pressure to the mold set, a unloader unit 20 for transporting the molded mold set, an upper mold transfer arm 21, an upper mold transfer arm controller 22, a body mold Transfer arm 23, body transfer arm controller 24, lower mold atmospheric pressure plasma cleaning head 25, lower mold head arm 26, lower mold head arm controller 27, upper mold atmospheric pressure plasma cleaning head 28, upper mold head It comprises an arm 29 and an upper mold head arm controller 30. The structures of the lower mold atmospheric pressure plasma cleaning head 25 and the upper mold atmospheric pressure plasma cleaning head 28 are the same as those of the cleaning apparatus used in the second embodiment of the present invention. In 4th Embodiment of this invention, the front-end | tip part of the filling part 17 or the upper mold | type transfer arm 21 plays the role of the cradle in 2nd Embodiment of this invention.

  The mold set K that has been molded is lifted by the upper mold transfer arm 21 controlled by the upper mold transfer arm controller 22 in the take-out unit 17 at the same position as the filling unit 17, and another location (not shown). Then, the processed molding material is lifted by the upper mold transfer arm 21 and stored in the processed molding material case 16. Next, the upper mold is picked up again by the upper mold transfer arm 21 and, when the upper mold is stationary, the upper mold atmospheric pressure plasma cleaning provided at the tip of the upper mold head arm 29 controlled by the upper mold head arm controller 30. The head 28 moves, and the upper die and the upper die atmospheric pressure plasma cleaning head 28 are arranged at positions where they face each other. Next, as in the second embodiment of the present invention, plasma is generated between the dielectric in the upper mold atmospheric pressure plasma cleaning head 28 and the molding surface of the upper mold, and the upper mold is irradiated by atmospheric pressure plasma irradiation. Clean the molding surface. That is, the tip of the upper mold transfer arm 21 constitutes an upper mold cleaning section.

  Further, in the take-out unit 17 at the same position as the filling unit 17, the trunk mold is lifted by the trunk mold transport arm 23 controlled by the trunk mold transport arm controller 24, and is retracted to another place (not shown), and then the lower mold The lower mold atmospheric pressure plasma cleaning head 25 provided at the tip of the lower mold head arm 26 controlled by the head arm controller 27 moves to the position of the lower mold on the filling portion 17, and lower mold and lower mold. The atmospheric pressure plasma cleaning head 25 is disposed at a position facing the stationary. Next, as in the second embodiment of the present invention, plasma is generated between the dielectric in the lower mold atmospheric pressure plasma cleaning head 25 and the upper and lower mold surfaces, and the lower mold is irradiated by atmospheric pressure plasma irradiation. Clean the molding surface. That is, the filling part 17 constitutes a lower mold cleaning part.

  Next, the trunk mold is lifted from the evacuation place by the trunk mold transfer arm 23, moved to the filling unit 17, and the lower mold is fitted into the trunk mold. Then, the molding material taken out from the unprocessed molding material case 15 is picked up by the upper mold transfer arm 21 and arranged on the lower mold on the filling unit 17. Next, the upper mold is lifted from the evacuation place by the upper mold transfer arm 21, moves to the filling unit 17, and the upper mold is fitted into the trunk mold. Thus, the molding material is filled between the pair of molds, and the mold set K is set.

  The mold set K is lifted up by the trunk mold transfer arm 23 and is disposed on a linear slider constituting the loader unit 18. The mold set K is conveyed through the loader unit 18, enters the molding unit 19, and is molded by applying heat and pressure. In addition, the structure of the shaping | molding part 19 is the same as that of what was demonstrated using FIG. 8 in the prior art example.

  After the molding, the mold set K is transported through the linear slider constituting the unloader unit 20, picked up by the trunk mold transport arm 23, and returns to the filling unit 17 again.

  By repeating the cycle as described above, it is possible to perform molding continuously with almost no maintenance of the mold. It is not necessary to perform cleaning with atmospheric pressure plasma every time one molding is performed, and it can be freely set according to the degree of contamination of the mold by molding, such as every 10 shots or every 100 shots by an automatic sequence. According to experience so far, it is possible to perform reliable cleaning without dropping tact, by performing cleaning roughly every 10 to 300 shots.

  In the embodiments of the present invention described above, several configuration examples have been shown as the electrode structure forming the atmospheric pressure plasma source (cleaning head), but various plasma sources can be used. For example, as shown in FIG. 6, even when the size of the dielectric 11 is considerably larger than the molding surface 5 in a standard-size mold, the electrode 4 is close to the molding surface 5, Otherwise, since the plasma 9 is generated only in the vicinity of the molding surface 5, there is no fear that the efficiency is almost lowered. That is, when such a head structure is used, plasma can be efficiently generated only in the vicinity of the molding surface for a mold having molding surfaces of various sizes. For example, the size (diameter) of the surface facing the molding surface of the electrode is preferably 1 mm or more and 10 mm or less. If it is less than 1 mm, arc discharge may occur. Conversely, if it is greater than 10 mm, the plasma will become too large when cleaning a small mold (because the plasma also wraps around the side of the mold), reducing efficiency. There is a risk of inviting. The size (diameter) of the dielectric is preferably 15 mm or more and 30 mm or less. If it is less than 15 mm, it is not suitable for processing a mold having a large molding surface. This is because the plasma wraps around the side surface of the electrode and power efficiency decreases. Conversely, if it is larger than 30 mm, it occupies more space than necessary, which is not preferable.

  In the embodiment of the present invention described above, the case where the molding surface is concave is illustrated. However, when the molding surface is convex as shown in FIG. 7, the shape of the dielectric 11 and the electrode 4 is changed to the molding surface 5. It is better to make the shape along. However, the curved surfaces do not have to be exactly the same, and a good processing result can be obtained if the curvature when approximated by a circle is approximately ± 20%. If the curvature is too different, a part of the molding surface may be insufficiently processed, and dirt may accumulate.

  Further, as shown in FIG. 8, an atmospheric pressure plasma source (cleaning head) having a large number of gas ejection ports can be used. In FIG. 8, the mold 2 is placed on the cradle 1. An electrode 4 is provided facing the cradle 1, and a shower electrode 31 and a shower plate 32 are provided on the electrode 4. The shower electrode 31 and the shower plate 32 are provided with gas ejection ports 10 at positions corresponding to each other. Gas is supplied from the gas supply device 7 to the gas reservoir 34 which is a space provided between the electrode 4 and the shower electrode 31 via the pipe 33 and is ejected onto the mold 2 through the gas ejection port 10. In this state, plasma is generated between the shower plate 32 and the mold 2 by supplying high frequency power of 13.56 MHz from the high frequency power source 8 to the cradle 1. The shower plate 32 is a dielectric, and a material having excellent insulating properties and heat resistance such as ceramics is used. Further, each of the above components is in the atmospheric pressure, and a completely sealed and sturdy container such as a vacuum container and a vacuum pump are not necessary.

  Further, a configuration as shown in FIG. 9 is also possible. In FIG. 9, the mold 2 is placed on the cradle 1. An electrode 4 is provided facing the cradle 1, and a shower electrode 31 and a shower plate 32 are provided on the electrode 4. The shower electrode 31 and the shower plate 32 are provided with gas ejection ports 10 at positions corresponding to each other. Gas is supplied from the gas supply device 7 to the gas reservoir 34 which is a space provided between the electrode 4 and the shower electrode 31 via the pipe 33. An insulating plate 35 is provided between the electrode 4 and the shower electrode 31, and the shower electrode 31 is grounded. In this state, when high frequency power of 13.56 MHz is supplied to the electrode 4 from the high frequency power supply 8, plasma is generated in the gas reservoir 34 between the insulating plate 35 and the shower electrode 31. Each of the above components is in the atmospheric pressure, and a completely sealed and sturdy container such as a vacuum container and a vacuum pump are unnecessary. Active particles generated by the plasma are ejected onto the mold 2 through the gas ejection port 10.

In addition, the cleaning rate may be improved by adding a gas containing fluorine. Alternatively, a fluorine-containing gas is preferably added to clean the molding surface to which inorganic substances such as SiO ₂ are adhered due to a molding error. In this case, CF ₄ or SF ₆ can be used. SF ₆ is easily dissociated and has an advantage that a large amount of fluorine radicals can be generated. In addition, a fluorocarbon gas such as HF, C ₂ F ₆ , or C ₄ F ₈ may be used.

  The mold cleaning method and apparatus and molding method and apparatus of the present invention can be applied not only to press molding but also to plastic injection molding processes. In addition, when the mold has a fine structure having a dimension of 10 nm or more and 10 μm or less, the effect of removing physical and chemical stains in the fine structure is high, which is particularly suitable. In addition, when the surface roughness required for the smooth portion of the mold is 1 nm or more and 100 nm or less, the effect of removing a very small amount of physical and chemical stains is high, which is particularly suitable. Representative of such molded products are optical products such as light guide plates for liquid crystal display backlights, optical disks, and optical pickups.

Sectional drawing which shows the structure of the cleaning apparatus of the metal mold | die in 1st Embodiment of this invention. Sectional drawing which shows the structure of the cleaning apparatus of the metal mold | die in 2nd Embodiment of this invention. Figure showing the dependence of the ashing speed on the distance between the lower surface of the electrode and the center of the molding surface Sectional drawing which shows the structure of the cleaning apparatus of the metal mold | die in 3rd Embodiment of this invention. The perspective view which shows the structure of the shaping | molding apparatus in 4th Embodiment of this invention. Sectional drawing which shows the structure of the cleaning apparatus of the metal mold | die in other embodiment of this invention. Sectional drawing which shows the structure of the cleaning apparatus of the metal mold | die in other embodiment of this invention. Sectional drawing which shows the structure of the cleaning apparatus of the metal mold | die in other embodiment of this invention. Sectional drawing which shows the structure of the cleaning apparatus of the metal mold | die in other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base 2 Mold 3 Gas jet 4 Electrode 5 Molding surface 6 Gas flow path 7 Gas supply device 8 Power supply 9 Plasma

Claims (9)

An electrode having a gas flow path is close to the molding surface of the mold, blowing the gas from Oite the gas flow path toward the molding surface of the mold to atmospheric pressure, a voltage is applied between the mold and the electrodes In the method of generating plasma between the mold and the electrode,
The surface of the electrode that faces the molding surface is covered with a dielectric material that forms a gas jet port that communicates with the gas flow path, and the inner diameter of the gas jet port is smaller than the inner diameter of the gas flow path. A mold cleaning method, comprising: cleaning the molding surface of the mold. Mold cleaning method according to claim 1, characterized in that the distance between the mold and the electrode and 0.5mm or 2mm or less. 3. The mold cleaning method according to claim 2, wherein a distance between the mold and the electrode is set to 1 mm or more and 1.5 mm or less. The inner diameter of the gas outlet provided in the dielectric is 0.1 mm or more and 0.5 mm or less, and the inner diameter of the gas flow path provided in the electrode is greater than 0.5 mm and 2 mm or less. Item 2. A mold cleaning method according to Item 1 . An electrode having a gas flow path ;
A gas supply device for supplying gas to the electrode,
A cradle for placing the mold;
The mold, and a power source for applying a voltage to the cradle or the electrode,
The surface of the electrode that faces the molding surface is covered with a dielectric material that forms a gas jet port that communicates with the gas flow path, and the inner diameter of the gas jet port is smaller than the inner diameter of the gas flow path. A mold cleaning apparatus characterized by the above. 6. The mold cleaning apparatus according to claim 5 , wherein a distance between the mold and the electrode is 0.5 mm or more and 2 mm or less. 7. The mold cleaning apparatus according to claim 6 , wherein a distance between the mold and the electrode is 1 mm or more and 1.5 mm or less. The inner diameter of the gas ejection port provided in the dielectric is 0.1 mm or more and 0.5 mm or less, and the inner diameter of the gas flow path provided in the electrode is greater than 0.5 mm and 2 mm or less. Item 6. A mold cleaning apparatus according to Item 5 . It has a filling portion for filling a molding material between a pair of molds, and a molding portion for molding by applying heat and pressure to the mold, and a take-out portion for taking out the molded molding material, and the claim A molding apparatus comprising the cleaning device according to any one of 5 to 8 .

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