JP3115707B2 - Stamper surface treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a surface of a metal stamper used for manufacturing a plastic information recording disk such as an audio disk and a video disk.

[0002]

2. Description of the Related Art An optical disc such as a video disc is formed by molding a plastic material such as an acrylic resin into a disk using a stamper having irregularities corresponding to an information signal as a mold, and then reflecting light onto a transfer surface of the signal. It is usually manufactured by providing a membrane. In addition, such a stamper for molding a disc is made conductive by applying electroless nickel plating or the like to the surface of a master having pits or the like corresponding to information signals formed on the surface thereof, and further electroforming the conductive film on the conductive film. In general, a thick nickel layer is applied by the method described above, and then the nickel layer is peeled off and the surface is cleaned.

In molding an optical disk using such a stamper, the efficiency of the molding operation is reduced or the surface of the molded body may be damaged if the releasability of the molded body such as an acrylic resin from the nickel stamper is not good. In some cases, a pattern may appear, and in some cases, there is a problem that a part of the resin remains on the surface of the stamper and an information signal reading error occurs. In order to faithfully capture the shape of the pits on the surface of the stamper, it has been proposed to incorporate various lubricants into the resin as a means to enhance the releasability between the stamper and the resin. It was not always easy to give the resin sufficient releasability without damaging the resin.

On the other hand, there is a method in which a solution of a release agent is applied to the surface of the stamper and dried. However, since the release agent tends to adhere to the concave portions, the shape of the transferred pits is deformed. Also, if a release agent adheres to the surface of the disk, the adhesion of the reflective film is reduced, or the deterioration of the reflective film is promoted, which may cause a signal reading error. Therefore, it is necessary to make the coating thickness of the release agent thin and uniform. However, the film of the release agent applied thinly has not only low durability but also poor reproducibility of the release effect. In order to prevent an increase in signal reading errors due to adhesion, there has been a problem that the coating process of a release agent must be frequently repeated on the surface of the stamper.

On the other hand, there has been proposed a method of forming, for example, a fluoropolymer film on the surface of a stamper by a CVD method. However, even with this method, in order to increase the durability of the polymer film, it is necessary to increase the thickness of the film, which inevitably changes the pit shape on the surface of the stamper.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for manufacturing a large number of molded products without producing deformation of the pit shape, producing a precise duplicate product, having high durability, and without increasing signal reading errors. An object of the present invention is to provide a stamper having a stable release performance such that it can be manufactured continuously, and to provide a surface treatment method of the stamper for imparting such highly reliable release performance. It was done.

[0007]

According to the present invention, in order to achieve the above object, the surface of a metal stamper for manufacturing an information recording disk is subjected to irradiation or plasma treatment, and then a higher aliphatic hydrocarbon or a higher aliphatic hydrocarbon is treated. A paint containing a compound selected from alcohols, higher fatty acids, and higher fatty acid derivatives was applied, and then the paint film was removed to treat the surface of the stamper.

In the method for treating a surface of a stamper according to the present invention, the irradiation of radiation is performed by irradiating a high-energy radiation such as an ultraviolet ray or an electron beam to activate the surface of the stamper. By contacting the plasma generated by a method such as glow discharge in an active gas atmosphere with the surface of the stamper,
It activates the surface.

[0009] The paint applied to the surface of the stamper thus activated is not particularly limited in properties, but may be higher aliphatic hydrocarbon, higher aliphatic alcohol,
It contains a compound selected from higher fatty acids and higher fatty acid derivatives and a solvent capable of dissolving the same, and further contains a film-forming material such as a synthetic resin if necessary, and optionally contains a filler or a plasticizer. May be included.

The higher aliphatic hydrocarbons contained in such paints include, for example, octadecane, icosane, docosan,
Those having a low vapor pressure such as polyethylene wax are preferred,
As higher aliphatic alcohols, for example, dodecanol,
Hexadecanol, octadecanol and the like are preferred. As higher fatty acids, for example, lauric acid, stearic acid, palmitic acid and the like are preferable, and as higher fatty acid derivatives, for example, metal salts, amides and esters of these acids are preferable.

Such a paint must be removed after it has been applied. As a method for this, a method of dissolving or swelling the coating film with an appropriate solvent and peeling it off can be adopted. When the strength of the film is sufficient, a method of peeling off without swelling may be used. At this time, it is necessary to completely remove the coating so as not to remain on the surface of the stamper.

[0012]

According to the surface treatment method for a stamper of the present invention, a compound selected from higher aliphatic hydrocarbons, higher aliphatic alcohols, higher fatty acids, and higher fatty acid derivatives is firmly bonded to the surface of the activated metal. It is thought that a molecular layer without defects is formed and a release surface with good durability can be obtained, and even if plastic molding is repeated many times, the release characteristics are not easily reduced and a precise disk with few defects Can be duplicated.

[0013]

【Example】

(First Embodiment) A nickel stamper A was prepared by subjecting an optical video disc master having a diameter of 30 cm to nickel electroforming and then peeling it off. The stamper A was mounted in a plasma processing apparatus, and subjected to a plasma discharge treatment for 3 minutes in an argon atmosphere at a pressure of 0.75 Pa under the conditions of an applied voltage of 12 kV and a current of 2.5 A to prepare a stamper B. Next, this was attached to a spin coater and, while rotating, 0.6% by weight of lauric acid and 0.4% by weight of stearyl alcohol.
Was coated on the surface, and then washed with pure acetone for 3 minutes while rotating, followed by washing with pure water for 1 minute and drying. Thus, a stamper C subjected to the surface treatment according to the method of the present invention was prepared.

(Second Embodiment) The same stamper A as used in the first embodiment was mounted at a position 17 cm below an ultraviolet lamp of 3 kW, and irradiation was performed for 3 minutes while rotating to prepare a stamper D. The stamper D was treated with the acetone solution X under the same conditions as in the first embodiment, and a stamper E having been subjected to the surface treatment according to the method of the present invention was produced.

(Third Embodiment) A stamper B obtained by performing a plasma discharge treatment under the same conditions as in the first embodiment is mounted on a spin coater, and while rotating, a special vinyl chloride copolymer resin paint Y (Fine Chemical Japan Co., Ltd.) Co., Ltd., trade name: CLEAN COAT S, solid content: about 22.5% by weight), and a paint Z obtained by adding 0.2% by weight of palmitic amide, 0.2% by weight of cetyl alcohol and 0.1% by weight of n-docosane It was applied to a thickness of 30 μm and dried at 40 ° C. for 15 minutes. After standing at room temperature for 24 hours in this manner, the coating film was carefully peeled off by hand to prepare a stamper F having been subjected to a surface treatment according to the method of the present invention.

(Fourth Embodiment) A resin paint Z is applied to a stamper D obtained by irradiating ultraviolet rays under the same conditions as in the second embodiment under the same conditions as in the third embodiment, and peeled off after 24 hours. Thus, a stamper G having been subjected to the surface treatment according to the method of the present invention was prepared.

(Comparative Example) The same stamper A as used in the first embodiment was treated with an acetone solution X under the same conditions as in the first embodiment, without being subjected to ultraviolet irradiation or plasma discharge treatment. H was created. Further, the same stamper A as used in the first embodiment was coated with the resin paint Z under the same conditions as in the third embodiment without performing ultraviolet irradiation or plasma discharge treatment, and was peeled off after 24 hours to obtain a stamper I of the comparative example. It was created.

Further, with respect to the same stamper A used in the first embodiment, palmitic acid amide, cetyl alcohol, n-docosane, etc. are not added under the same conditions as those in the first embodiment without ultraviolet irradiation or plasma discharge treatment. The resin paint Y is applied, and after 24 hours, the resin paint Y is peeled off and the stamper J of the comparative example is removed.
It was created. Further, the resin paint Y was applied in the same manner as described above on the stamper B that was subjected to the plasma discharge treatment under the same conditions as in the first embodiment and the stamper D that was irradiated with ultraviolet light under the same conditions as in the second embodiment. Thereafter, they were peeled off to prepare stampers K and L of Comparative Examples.

(Test Example 1) Each of these stampers was attached to a mold of an injection molding machine, and a methacrylic resin (Mitsubishi Rayon, product number TF-3) was used as a molding material at a cylinder temperature of 260 ° C and a mold temperature of 60 ° C. The stamper surface was visually inspected while performing injection molding of the video disk under the conditions, and the occurrence of resin adhesion to the stamper was examined. In other words, if the occurrence of resin adhesion to the stamper is recognized before the number of times of injection molding reaches 48, it is determined that “there is adhesion”,
If no resin adhesion to the stamper was observed even when the number of injection moldings was more than 48, it was judged as "no adhesion". In order to examine the reproducibility of the mold release performance, a molding test was performed under the same molding conditions on ten stampers having the same type of surface treatment, and the number of cases where resin adhesion occurred was shown in Table 1 as a resin adhesion occurrence rate. Was.

[0020]

[Table 1] ───────────────────────────── Stamper pre-treatment Coating chemicals Resin adhesion rate ──────── Ａ A ^* --8 B ^* Plasma treatment -10 C Plasma treatment solution X 0 D ^* UV irradiation -10 E UV irradiation solution X 0 F plasma processing paint Z 0 G ultraviolet irradiation paint Z 0 H ^* - solution X 8 I ^* - paint Z 4 J ^* - paint Y 7 K ^* plasma treatment paint Y 3 L ^* ultraviolet radiation paint Y 3 ────── ─────────────────────── *: Comparative example

According to these results, a paint containing a compound selected from higher aliphatic hydrocarbons, higher aliphatic alcohols, higher fatty acids, and higher fatty acid derivatives was simply applied to the surface of the stamper, and then the paint film was removed. Is not enough to prevent resin adhesion,
According to the method of applying the coating containing the above compound after the surface of the stamper is irradiated with ultraviolet rays or plasma beforehand, it can be seen that the occurrence of resin adhesion can be effectively prevented.

(Test Example 2) Using the stamper G prepared in the fourth embodiment, a video disk of methacrylic resin was continuously injection-molded, and an aluminum reflective film was deposited thereon to produce 144 disks. . During this time stamper G
No adhesion of resin was observed on the surface of. Further, a total of 24 video discs were extracted from the obtained video discs every 6 discs, and a signal reading test was performed to check the error occurrence rate. As a result, all of them showed low level values within the standard range. It was confirmed that the quality was excellent.

[0023]

According to the stamper surface treatment method of the present invention, a highly durable stamper having excellent resin adhesion preventing performance and capable of continuously producing a large number of high-quality optical discs. Is obtained. Therefore, not only can the frequency of the release agent processing operation on the stamper be reduced, but also the number of stampers used for disk manufacture can be reduced, which is effective in increasing the productivity of the disk.

Claims (2)

(57) [Claims] After irradiating or irradiating the surface of a metal stamper for producing an information recording disk with radiation or plasma, a compound selected from higher aliphatic hydrocarbons, higher aliphatic alcohols, higher fatty acids and higher fatty acid derivatives is obtained. A method for treating a surface of a stamper, characterized by applying a paint containing the paint and then removing the paint film. 2. The method according to claim 1, wherein the radiation is ultraviolet light.