JP5709238B2 - Mold with release film - Google Patents

Description

  The present invention relates to a release film for realizing a mold having good releasability. In particular, the present invention relates to a release film effective for improving the release property of a mold having nanometer-size irregularities. The mold having the release film of the present invention is, for example, a fine antireflection molded product composed of nanostructures, a biochip with nanopillars, a light guide plate with micrometer-sized irregularities, and the like. This is useful in forming irregularities.

  Conventionally, when a molded product is manufactured using a mold having fine irregularities formed on the surface or a mold that requires high surface accuracy, the mold is not separated from a molded product such as plastic resin or glass. Due to inadequate moldability, it has been a problem that defects occur in molded products.

In general, a mold release layer is formed on the outermost surface of the mold in order to improve the mold releasability between the mold and the molded product. Specifically, a cemented carbide mainly composed of tungsten carbide (WC) as a base material, or cermet mainly composed of titanium nitride (TiN), chromium carbide (Cr ₃ C ₂ ), and alumina (Al ₂ O ₃ ). Or a mold made of chromium (Cr), molybdenum (Mo), nickel (Ni), cobalt (Co), tungsten (W), titanium (Ti), stainless steel (SUS), silicon carbide (SiC), etc. An intermediate layer made of metal, carbide, or nitride is combined on the surface, and a fluorine-based organic material or platinum (Pt), palladium (Pd), iridium (Ir), rhodium (Rh), osmium (on the outermost surface) Os), ruthenium (Ru), rhenium (Re), composed of inorganic materials such as tungsten (W) (see Patent Documents 1 to 3) That provided a release layer, thereby realizing a releasability improving the mold.

  However, the present situation is that the improvement of releasability is not sufficiently solved by these methods when the mold has a complicated mold in which fine irregularities are formed on the mold surface.

  For example, when the above-described release film is applied to a mold surface provided with nanometer-sized irregularities such as an antireflection structure (such as a moth-eye type antireflection structure) that can be realized with a nanostructure, an optical disk substrate, a grating, A material satisfying all the requirements such as better release properties (moldability) and excellent repeated durability of the release film (thin film hardness, thin film adhesion, cracking strength) has not been obtained.

  That is, when a mold release layer made of an organic material is provided on the outermost surface (molding surface) of a mold having nanometer-sized irregularities, there is an advantage that good mold release properties can be realized. However, the release layer made of an organic material has a problem that the repetition durability is not sufficient and the number of times it can be molded is small. On the other hand, a release layer made of an inorganic material such as platinum (Pt), palladium (Pd), iridium (Ir), rhodium (Rh), osmium (Os), ruthenium (Ru), rhenium (Re), tungsten (W), etc. However, there is a problem that good releasability cannot be realized, although repeated durability can be obtained.

  For this reason, at present, molding is performed by improving the mold release property of the resin. For example, an additive for improving releasability is filled in a resin used for molding. However, since it is generally required that molds can be molded with many types of resins as characteristics required for molds, improvement of mold releasability of these molds themselves is further required.

  In addition to the above-described thin films, titanium nitride (TiN), chromium nitride (CrN), tantalum nitride (TaN), carbon nitride (CN), niobium nitride (NbN), and the like are thin films exhibiting excellent releasability. It is known (see Patent Documents 4 to 6). However, these are also not sufficient as a release film for improving the mold releasability of a mold having fine irregularities, and nanometer-sized irregularities formed at intervals below the wavelength in the visible range are formed on the surface. When used in the formed antireflection function-providing mold, the releasability becomes poor and a molded product having sufficient low reflection characteristics cannot be obtained.

Japanese Patent Application Laid-Open No. 07-172849 JP 2005-231932 A JP 2009-0667607 A JP 2009-061465 A JP 2007-277019 A Japanese Patent Laid-Open No. 10-278049 JP 2006-307323 A JP 2008-143162 A JP-A-2005-331868

  The present invention provides a release film that achieves good mold releasability and improved molding durability, and can produce a good molded product. In particular, for molds with irregularities of nanometer size (such as anti-reflection molds), it achieves releasably better release properties and repeatability compared to conventional release films. The purpose is that.

  In order to solve the above problem, in the present invention, a noble metal nitride produced by a vacuum film forming apparatus such as sputtering or PVD, that is, platinum (Pt), palladium (Pd), gold (Au), rhodium (Rh). , Osmium (Os), ruthenium (Ru), iridium (Ir), rhenium (Re) or their alloys nitrides were used as release films. Among these, platinum nitride (Pt—N) has a particularly excellent effect.

Specifically, this application provides the following invention.
(1) A mold release film containing a noble metal nitride as a main component.
(2) The noble metal is platinum (Pt), palladium (Pd), gold (Au), rhodium (Rh), osmium (Os), ruthenium (Ru), iridium (Ir), rhenium (Re), and alloys thereof. The release film according to (1), wherein the release film is selected from the group consisting of:
(3) The release film according to (2), wherein the noble metal is platinum (Pt).
(4) The release film according to (2), wherein the noble metal is palladium (Pd).
(5) The release film according to (2), wherein the noble metal is an iridium (Ir) -rhenium (Re) alloy.
(6) A mold having a base material, a cemented carbide layer having irregularities formed on the surface, and a release film according to any one of (1) to (5).
(7) The mold according to (6), wherein the mold is a mold for resin molding or glass molding.
(8) The mold according to (7), wherein the mold is a mold for injection molding, press molding, cast molding, transfer molding, or nanoimprint molding.
(9) The mold according to (8), wherein the mold is a mold having fine unevenness.
(10) The mold according to (9), wherein the mold is a mold having irregularities of nanometer size for forming an antireflection structure.

  Noble metal nitrides such as platinum (Pt), palladium (Pd), gold (Au), rhodium (Rh), osmium (Os), ruthenium (Ru), iridium (Ir), rhenium (Re), and alloys thereof The release film of the present invention used is useful as a release film for improving the release property of a mold having fine irregularities. Therefore, the release film of the present invention is useful for resin molding and glass molding, and is used for injection molding dies, press molding dies, cast molding dies, transfer molding dies, and nanoimprint molding dies. It can be applied as a release film to be applied.

It is a figure which shows the light transmittance of the molded article obtained using the metal mold | die for antireflection structure which has a release film which consists of platinum nitride or platinum. It is a figure which shows the mass loss by the heating of a platinum release film and a platinum nitride release film.

  First, the releasability of a release film made of various metals and alloys and nitrides thereof will be described in detail.

  Table 1 shows the contact angle of the release film made of each material with respect to pure water. The contact angle with respect to pure water was determined by using DM-300 manufactured by Kyowa Interface Chemical Co., Ltd., a sample in which an intermediate layer having a thickness of 200 nm and a release layer of various materials having a thickness of 200 nm were laminated on the surface of a flat silicon wafer. It was measured. In general, the greater the contact angle, the lower the surface energy and the weaker the adhesion. Therefore, the larger the contact angle, the better the releasability.

  According to Table 1, for platinum (Pt), palladium (Pd), gold (Au), and iridium-rhenium alloy (Ir-Re), the contact angle of nitride is larger than that of metal or alloy, and separation by nitriding occurs. It can be seen that improved moldability is obtained. Therefore, noble metals such as platinum (Pt), palladium (Pd), gold (Au), rhodium (Rh), osmium (Os), ruthenium (Ru), rhenium (Re), etc., are used as they are as the release film. Compared with the case (refer patent documents 1-3), it turns out that these metals can improve mold release property by nitriding. Similar effects can be expected with alloys and mixed materials containing these materials as main components.

  On the other hand, tungsten (W) metal (see Patent Documents 1 to 3) and nitrides of titanium (Ti), tantalum (Ta) and niobium (Nb) used in the conventional release film (Patent Document 4) When the contact angles of the metals and nitrides in Table 1 are compared, the contact angle is not necessarily increased by nitriding, but is often decreased. From this, it can be seen that these metals do not always have the result of improving the releasability by nitriding.

  Therefore, in the noble metal release film, the contact angle is improved by nitriding and the release property can be improved.

  From the results in Table 1, among the release films containing the noble metal nitride of the present invention, the release film containing platinum nitride (Pt—N) or palladium nitride (Pd—N) as a main component, or platinum nitride or nitride It can be seen that a release film containing palladium as a mixed material can provide particularly good release properties compared to the above-described conventional release films. Further, a release film containing nitrides of gold (Au), rhodium (Rh), osmium (Os), ruthenium (Ru), iridium (Ir) and rhenium (Re) as a main component, or nitrides of these metals The same effect could be confirmed with a release film containing as a mixed material.

  In addition, with regard to the repeated durability of the aforementioned release film, it is repeatedly formed using a sample mold in which a release film having a thickness of 50 nm is formed on the surface of a flat plate mold having a diameter of 30 mm via an intermediate layer. Then, evaluation was performed from the occurrence of resin contamination on the mold surface due to the number of moldings (10,000 times) and the occurrence of point defects on the design surface of the molded product caused by molding defects. Here, the evaluation was repeated using polycarbonate, ZEONEX (registered trademark, cycloolefin polymer resin), acrylic, and the like as the molding resin. The evaluations of these molding resins were combined to evaluate repeated durability.

The release film containing the noble metal nitride of the present invention as a main component is based on the weight of the release film.
50% or more, preferably 85% or more of a noble metal nitride is included. Further, the noble metal nitride contained in the release film preferably contains a nitride component (N) of 10% or more, preferably 30% or more by mass ratio. The release film of the present invention may contain a small amount of impurities on condition that the performance is not adversely affected.

  The release film made of the noble metal nitride of the present invention can be formed using a vacuum film formation technique such as sputtering (including reactive sputtering), PVD, or the like. Alternatively, a release film made of a noble metal nitride can be formed using other techniques such as a sol-gel method. From the viewpoint that a dense film of noble metal nitride can be formed, it is preferable to form a release film using a vacuum film forming technique.

  The release film of the present invention desirably has a thickness of 5 nm to 200 nm. A release film having a film thickness of less than 5 nm is effective in improving mold release properties, but there is a risk that repeated durability will be lowered. Further, in a release film having a film thickness exceeding 200 nm, there is a risk that repeated durability may be lowered due to the influence of film stress.

  The metal mold | die for applying the release film of this invention can be manufactured by the method of a prior art (refer patent document 8 and 9).

  Next, with respect to the best embodiment for using a platinum nitride film as a mold release film, an example of a mold for producing an antireflection structure in which unevenness controlled to be equal to or less than a wavelength interval in the visible range is formed on the surface And will be described in detail below.

  First, an adhesion layer is formed on the surface of a base material such as nickel (Ni), stainless steel (SUS), tungsten carbide (WC) using titanium (Ti), nickel (Ni), chromium (Cr), Subsequently, a cemented carbide layer was formed. Here, the super hard layer is preferably formed using silicon nitride, titanium nitride, diamond-like carbon (DLC), carbon nitride, or the like. Subsequently, unevenness of nanometer size for transferring to the molded product is formed on the surface of the cemented carbide layer. In the case of the antireflection structure, for example, irregularities having a height of 160 nm are formed at irregularity intervals controlled at intervals of 300 nm or less. The nanometer-sized unevenness forming method on these super hard layers is a metal of any one of gold, silver, platinum, or palladium, an alloy mainly containing any of gold, silver, platinum, or palladium, or By using a metal nanoparticle heated by using a metal oxide of gold, silver, platinum, or palladium as a mask material, the carbide layer is etched by a dry etching process, so that the nanometer-sized irregularities can be increased. A hard layer was prepared. Here, non-metallic silica colloids or organic particles can be used as the nanoparticles as the mask material. As an alternative method, the nanometer-sized unevenness of the cemented carbide layer may be formed using a mask formed not by nanoparticles but by other lithography methods. As a further alternative, a self-assembled film such as an alumina hole can be used as a mask material for forming the irregularities of the cemented carbide layer.

  After producing nanometer-sized irregularities on the surface of the cemented carbide layer, an intermediate layer made of titanium (Ti), nickel (Ni), chromium (Cr), etc. is formed, followed by a release film made of platinum nitride. By doing so, the metal mold | die of this invention which has the unevenness | corrugation of nanometer size, and the release film was formed in the molding surface can be obtained. Similarly, a mold having a release film containing another metal nitride as a main component can be obtained.

  In the present invention, “nanometer-sized unevenness” means unevenness having an unevenness interval and an unevenness height of less than 1 micrometer. Preferably, “nanometer-sized unevenness” means unevenness having an unevenness interval and an unevenness height of 700 nanometers or less. More preferably, “a nanometer-sized unevenness” means an unevenness having an unevenness interval and an unevenness height of 300 nanometers or less, which is not more than the wavelength of light in the visible range.

  A mold having nanometer-sized irregularities formed as described above and having a release film formed on its molding surface can be used for molding a resin or glass. Said metal mold | die can be used in techniques, such as injection molding, press molding, cast molding, transfer molding, and nanoimprint molding.

  The present embodiment relates to a mold for producing an antireflection structure in which unevenness controlled to be equal to or less than a wavelength interval in the visible range is formed on the surface. First, an adhesion layer was formed on the nickel base material surface using chromium (Cr), and then a super hard layer was formed using silicon nitride. Subsequently, nanometer-sized irregularities having an irregularity interval of 100 nm and an irregularity height of 160 nm were formed on the surface of the cemented carbide layer by dry etching using gold nanoparticles as a mask material.

  After producing nanometer-sized irregularities on the surface of the cemented carbide layer, an intermediate layer made of chromium (Cr) with a thickness of 5 nm is formed, and subsequently a release film made of platinum nitride with a thickness of 10 nm is formed, A mold having nanometer size irregularities and having a release film formed on the molding surface was obtained. Here, an intermediate layer and a platinum nitride release layer were formed using a reactive sputtering apparatus. Specifically, by using a target made of chromium and applying a bias voltage to the hard layer, which is the film formation substrate, while generating a plasma in an argon atmosphere, the pinhole (thin film removal) becomes more precise. An intermediate layer made of chromium (Cr) without any metal was formed. The film formation pressure at this time was 0.5 Pa, and the film formation rate was 0.3 Å / second. The film was formed under the conditions that the RF power during film formation was 100 W and the bias voltage to the substrate was 25 W. Subsequently, using a platinum target, a bias voltage is applied to the super hard layer, which is a film formation substrate, while plasma is generated in an atmosphere of nitrogen and argon, and nitrogen and platinum are reacted, thereby achieving a finer structure. A release film made of platinum nitride without pinholes (thin film loss) was formed. The film formation pressure at this time was 0.5 Pa, and the film formation rate was 2.9 K / sec. The film was formed under the conditions that the RF power during film formation was 100 W and the bias voltage to the substrate was 25 W. Using a similar method, a mold having a release film made of the metal or metal nitride shown in Table 1 was manufactured. However, when forming a release film made of metal, a release film was obtained by performing a sputtering process in an argon atmosphere not containing nitrogen.

  Subsequently, molding of the resin material using the mold obtained as described above will be described in detail. For the molding, molding was performed under molding conditions described later using an all-electric injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd.). As the resin, Acrypet (registered trademark) VH (Mitsubishi Rayon Co., Ltd., acrylic resin) was used. For molding, conditions of a mold temperature of 100 ° C., a resin temperature of 280 ° C., and a holding pressure of 60 mPa were used. The better the mold releasability between the mold and the resin material, the more accurately the nanometer-size irregularities can be formed, so that a better antireflection effect can be realized. In addition, since the transmittance is improved together with the antireflection effect, a mold having good releasability is useful for manufacturing an optical lens exhibiting high transmittance. FIG. 1 shows a case in which a metal mold for producing an antireflection structure having nanometer-sized irregularities formed on its surface is used, and the platinum nitride film of the present invention is used as a release film, and a conventional platinum film is used. In the case, the result of measuring the light transmittance of the molded product when no release film was used was shown. In FIG. 1, when the result of using the conventional platinum release film and the result of using the platinum nitride release film of the present invention are compared, the use of platinum nitride as the release layer increases the transmittance. It can be seen that a molded product is obtained. This is because good transmission optical characteristics were obtained as a result of improved mold release properties between the mold and the resin material. Moreover, the releasability of the resin with respect to the unevenness of nanometer size was evaluated by observing the surface of the mold after molding. The criteria for determining the releasability of the resin for nanometer-sized unevenness at this time is good without appearance defects on the design surface, and the reflectance of the molded product when molded using a mold with an antireflection nanostructure A case where the characteristic is 0.5% or less is marked as ◎, and there is no appearance defect on the design surface, which is good, but a mold release film having a reflectance property of 0.5% to 1% is indicated as ◯ This is good without appearance defects, but the molded product has a reflectance property of 1% to 2%, or the molded product has a reflectance property of 1% or less. A release film having appearance defects was evaluated as Δ, and a release film having appearance defects on the design surface and having a reflectance characteristic of 1% or more was evaluated as x, and the results are shown in Table 1.

  FIG. 2 shows the results of measuring weight loss when the platinum nitride film of the present invention and the conventional platinum film are heated. As shown in FIG. 2, when platinum of the prior art is used, the heat resistance limit is about 600 ° C., whereas the release film made of platinum nitride of the present invention has a heat resistance up to about 750 ° C. It turns out that it has sex. Therefore, by using a release film made of platinum nitride, molding at a higher temperature required for press molding of glass or the like can be performed. That is, it can be seen that the release film of the present invention made of a noble metal nitride can achieve an improvement in heat resistance in addition to an improvement in the release property.

  From these results, it can be seen that platinum nitride is useful as a release film and can improve the mold release property. In particular, when the unevenness is fine and has a high aspect ratio (the unevenness height / unevenness interval is 1 or more), the mold release property of the mold is generally significantly deteriorated. Therefore, the release film of the present invention has nanometer-sized unevenness. It is particularly useful as a release film for transferring.

  As shown in Table 1, in addition to the platinum nitride release film shown in FIG. 2, palladium nitride is also a nanometer-sized release film as a mold release film having nanometer-size irregularities formed thereon. It is useful as a release film for transferring irregularities.

Claims (4)

A mold for resin molding or glass molding, wherein the mold has a base material and a release film located on the outermost surface and containing a nitride of a noble metal as a main component , and the noble metal is platinum A mold selected from the group consisting of (Pt) and palladium (Pd) . The mold according to claim 1 , wherein the outermost surface has irregularities having an irregularity interval and an irregularity height of 1 micrometer or less . The mold according to claim 2 , wherein the uneven spacing and uneven height are 300 nanometers or less . The mold according to any one of claims 1 to 3, wherein the mold is a mold for injection molding, press molding, cast molding, transfer molding, or nanoimprint molding.

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