JP5745623B2 - Surface treatment mold and mold surface treatment method - Google Patents

Description

The present invention relates to a surface-treated mold having a silazane film on the outermost layer directly or via an intermediate film on at least a shaping surface of the mold. In the specification and claims of the present application, the “metal mold” basically includes a movable mold and a fixed mold, and refers to a split mold that forms a cavity when closed, and is a flat plate or roll stamper. Is excluded.

  In particular, it is effective in improving mold releasability of a mold having a shaping surface having a size of 100 μm or less and further having a nanometer size unevenness. For example, it is a surface treatment mold that is useful in the production of anti-reflective molded products composed of nanostructures, biochips with nanopillars, and light guide plates with micrometer-sized irregularities, etc. .

  Conventionally, when manufacturing molded products using molds with irregularities ranging from fine μm size (100 μm or less) to nm size on the surface or molds that require high surface accuracy, the molding process However, the mold releasability between the mold and the resin molded product becomes a problem, and it is a problem that defects occur in the molded product.

  In order to solve these problems, the outermost surface of the mold has been surface treated to improve the releasability.

  For example, in Patent Document 1, a functional group (for example, hydrolysis containing a silicon atom) that chemically reacts with a mold material (base material) in a mold (imprint processing mold) having nm-size irregularities. An invention has been proposed in which releasability is improved by surface treatment (immersion) with a specific perfluoropolyether introduced with a functional group (see paragraph 0012) (see summary, claims, etc.).

  However, it has been found that the surface treatment has problems in release heat resistance (release property under heating) and release durability (release property after repeated molding).

  Although it does not affect the patentability of the present invention, in Patent Document 2, the same surface treatment agent (perfluoroalkyl group-containing triaminosilane) as used in the present invention is used to form an optical member (organic glass). A technique for forming a water-repellent thin film has been proposed.

  However, the optical member does not require release heat resistance and release durability as in the mold shaping surface. The mold shaping surface is repeatedly exposed to high heat and high pressure fluid (molten resin; 200 ° C. or higher) during injection molding, etc. Further, in the case of a thermosetting resin, it is necessary to heat until the resin curing is completed. is there. Such high heat resistance and durability are unexpected in the optical member.

JP 2007-326367 A JP-A-5-215905

  An object of the present invention is to provide a surface treatment mold and a mold surface treatment method capable of realizing high mold release heat resistance and mold release durability and capable of repeatedly and stably producing good molded products.

  In particular, the effect becomes remarkable when applied to molding of a molded article having irregularities of 100 μm or less (for example, a light guide plate, a microlens array, etc.), or even nm-sized irregularities (for example, a molded product with an antireflection function). An object is to provide a surface treatment mold and a surface treatment method for the mold.

  As a result of diligent development in order to achieve the above object, the present inventors have found that the releasability of the surface treatment mold is remarkably improved if the following configuration is adopted.

At least on the shaping surface of the mold, a surface treatment mold having a silazane film on the outermost layer,
The silazane film is composed of a polycondensation crosslinked product having a perfluoroalkyl group-containing triaminosilane represented by the following structural formula as a monomer or a main monomer, and is chemically bonded to a mold base material or an adjacent intermediate film. Surface treatment mold characterized by.

C _n F _{2n + 1} C _m H _2m Si (NH ₂ ) ₃ (however, n = 2 to 10, m = 1 to 4)
At least on the shaping surface of the mold, a surface treatment mold comprising a silazane film on the outermost layer directly or via an intermediate film on the mold base material,
The silazane film is composed of a polycondensation crosslinked product having a perfluoroalkyl group-containing triaminosilane represented by the following structural formula as a monomer or a main monomer, and is chemically bonded to the mold base material or an adjacent intermediate film. It is characterized by.

  The ranges of n and m are determined from the availability of silazane materials and the ease of synthesis, and are relative.

  The surface treatment mold having the above-described structure is remarkably release heat resistant as compared with the conventional surface-treated mold coated with hydrolyzable silane group-introduced perfluoropolyether (silicon-containing organic fluoropolymer: see paragraph 0022). As well as improved mold release durability. The release heat resistance / durability is further improved when the silazane film forming surface is a plasma treated surface.

  When the mold forming surface is a nanostructure, it is necessary to form an intermediate film with a super hard film of HV1000 or higher (JIS 2244: ISO6507) even if the mold base material itself is hard. In the case where the mold base material itself is less than HV1000, it is possible to expect improvement in the shaping surface durability of the mold by forming an intermediate layer with a super hard film. The super hard film is desirably formed of one or more of Si nitrides / carbides or oxides.

  Moreover, when it is predicted that the adhesion between the cemented carbide film and the mold base material is insufficient, the intermediate film is a transition metal selected from the group of the third period 4 to 10 genera. Or an alloy thereof to form an adhesion film.

  The silazane film of the present invention has a contact angle decrease in a release heat resistance test (300 ° C. × 24 h) within 20%, preferably within 10%.

  When the surface treatment mold having each of the above configurations is applied to a mold having an irregular surface with a shaping surface of nm size, it is desirable that the thickness of the silazane film is 5 to 50 nm. If the film thickness is too thin, it is difficult to obtain durability, and if the film thickness is too thick, there is a risk that nm-sized irregularities will be buried.

  In the surface treatment method of the surface treatment mold, it is desirable to form the silazane film by vacuum deposition. The film uniformity (leveling property) of the silazane film is easy to ensure compared to the dipping method.

  Further, prior to forming the silazane film, the silazane film forming surface is preferably subjected to oxygen plasma treatment. The release heat resistance and release durability of the silazane film are improved.

  The oxygen plasma conditions are RF power 50 to 1000 W × 5 to 3600 s. Below the lower limit of the above conditions, it is difficult to impart the required hydrophilicity to the silazane film forming surface by oxygen plasma, and it is difficult to obtain a chemical bond with the silazane film. If the value exceeds the upper limit, no further improvement in hydrophilicity can be expected, which is useless.

  The technical idea of the present invention can be applied to a structure requiring water repellency (contamination resistance), and the surface treatment structure can be expressed as follows.

A surface treatment structure (excluding an optical member) provided with a silazane film as a surface treatment film on the outermost layer directly or via an intermediate film on a mold base material,
The silazane film is made of a polycondensation crosslinked product of a perfluoroalkyl group-containing triaminosilane (monomer) represented by the following structural formula, and is chemically bonded to a mold base material or an adjacent intermediate film. .

C _n F _{2n + 1} C _m H _2m Si (NH ₂ ) ₃ (however, n = 2 to 10, m = 1 to 4)
The surface treatment method of the surface treatment structure can be expressed as follows.

  In the surface treatment method of the surface treatment structure, the silazane film forming surface is subjected to oxygen plasma treatment before the silazane film is formed.

It is a fragmentary sectional view (film | membrane block diagram) of the surface treatment metal mold | die in this invention. It is a graph which shows the test result of the heat resistance test in each surface treatment film | membrane (release film) of an Example and a comparative example. It is a graph which similarly shows the test result of mold release durability (rubbing test). It is a graph which shows the reflectance characteristic after continuous shaping | molding 10,000 times in the resin molding die (real machine) which gave the surface treatment film | membrane (release film) of this invention.

  Hereinafter, an embodiment of the present invention will be described in detail. In FIG. 1, the fragmentary sectional view of the metal mold | die 10 is shown.

  The mold 10 is a surface-treated mold having a silazane film (release film) 15 on the outermost layer directly or via an intermediate film 13 on the mold base 11 at least on the shaping surface 10a.

In addition, the kind of metal mold | die 10 is not specifically limited. For example, various molds for injection molding, press molding, cast molding, transfer molding and the like can be mentioned.

  Here, the forming material of the mold 10 is not particularly limited. For example, metals such as Fe, Al, Ni, Zr, and Si or alloys thereof; ceramics such as WC, SiC, and NiP; hard resins such as epoxy, polyester, acrylic resin, and polycarbonate; and other inorganic glass and organic glass be able to. Of these, NiP, SUS, and WC are preferable. This is because it has high hardness and excellent heat resistance and is suitable as a mold material. NiP and SUS have a track record as a mold material for injection molding, and WC has a track record as a mold material for glass molding.

  The silazane film 15 is an intermediate film (superhard film) made of a polycondensation cross-linked product containing a perfluoroalkyl group-containing triaminosilane represented by the following structural formula as a monomer or a main monomer, and adjacent to or adjacent to the mold base material 11 It is chemically bonded to 13b.

C _n F _{2n + 1} C _m H _2m Si (NH ₂ ) ₃ (however, n = 2 to 10, m = 1 to 4)
Here, when “n = 1”, the perfluoro group (CF ₂ ) of the polymer repeating unit is insufficient and it is difficult to obtain the required releasability. When “n ≧ 11”, the monomer molecular weight increases and the solvent dissolves. Problems are likely to occur, and handling is reduced. In addition, the number of products on the market is up to n = 8.

Also, those having “m = 0” are difficult to synthesize, and if “m” is 5 or more, the perfluoro group (CF ₂ ) of the polymer repeating unit is insufficient and it is difficult to obtain releasability.

  From the viewpoint of easy availability (ease of synthesis) and ease of obtaining the effects of the present invention (heat resistance and durability (adhesiveness) of the silazane film), n = 4 to 8, m = 2. It is desirable to set to ~ 4.

  Here, when a perfluoroalkyl group-containing triaminosilane is used as a main monomer, examples of the monomer to be combined include a diaminosilane and a monoaminosilane containing a perfluoroalkyl group or having other functional substituents. These various aminosilanes can be appropriately blended in amounts that do not impair the effects of the present invention (heat resistance and durability (adhesiveness) of the silazane film).

In the present invention, the aminosilane is condensed with deammonia (NH ₃ ) to form a condensation polymerized crosslinked product, and the amino group is partially dehydrated in the same manner as the silane coupler. It is thought to be chemically bonded to active hydrogen such as the above hydroxyl group.

  Then, it is considered that the surface density of the hydroxyl group is increased by subjecting the silazane film forming surface to oxygen plasma treatment, and as shown in the examples to be described later, the heat resistance and the durability increase as the adhesion increases.

  Here, the thickness of the silazane film is 5 to 50 nm, preferably 5 to 30 nm.

  The silazane film is usually formed by a conventional film forming method using the aminosilane solution. For example, any of a dipping method, a spin coating method, a spray method, a gas phase method, and a vacuum deposition method may be used.

The intermediate film 13 is not inevitable, but when the mold base material has a Vickers hardness (JIS Z 2244 (ISO 6507); hereinafter simply referred to as “hardness”) of less than 1000 HV , the inner adhesive film 13a and the outer From the viewpoint of durability (particularly, abrasion resistance), it is desirable that the super hard film 13b is formed. For example, the Vickers hardness is 320 HV for SCr440 (chromium steel) frequently used in molds and 722 HV for SKH4 (high speed tool steel).

The material for forming the adhesion film 13a is a group of groups 4 to 11 (Ti, Ta, Nb, Cu, W, Cr, Ni, Zr, Mo, Pt, Au, Ag, Ir, 4th to 6th periods ). , Re, Pd, etc.) and Si, Al, etc. can be used, but in particular, the group of groups 4 to 10 (Ti, V, Cr, Mn, Co, Ni) of the fourth period can be used. Furthermore, Ti, Ni, and Cr are desirable because they have a high adhesion increasing effect. These have a track record as an adhesion film between metals.

  This adhesion film is formed by vacuum deposition, sputtering, ion plating, or the like.

Examples of the super hard film include various nitrides such as Si ₃ N ₄ , SiC, SiO ₂ , TiN, Al ₂ O ₃ , DLC, and C ₃ N ₄ , carbides, and oxides. Nitride (Si ₃ N ₄ ), carbide (SiC), and oxide (SiO ₂ ) are desirable. This is because it has excellent affinity (adhesion) with the silazane film.

  The superhard film has a thickness of 5 to 1000 nm, preferably 10 to 600 nm.

  It is desirable to form this super hard film by reactive sputtering because it is easy to form the super hard film.

  Examples carried out together with comparative examples to confirm the effects of the present invention will be described below.

A. Preparation of test piece <Example 1>
An adhesion film (Cr, film thickness: 10 nm) was formed on an inorganic glass substrate (mold base material: 26 mm × 76 mm × 1 mmt) using a reactive sputtering apparatus. The film forming conditions were such that the degree of vacuum was 0.5 Pa and the substrate temperature was 300 ° C.

A super hard film (Si ₃ N ₄ , film thickness 500 nm) was formed on the adhesion film by a reactive sputtering apparatus. The film formation conditions were the same as those for the adhesion film.

Thereafter, oxygen plasma treatment (RF: 500 W, treatment time 600 s) was performed, and a silazane film (film thickness: 15 nm) was formed by a vacuum deposition method using a perfluoroalkyl group-containing silazane compound (KP-801M manufactured by Shin-Etsu Chemical Co., Ltd.). A film was prepared as a test piece. The film forming conditions were as follows: degree of vacuum: 2 × 10 ⁻³ Pa, substrate temperature: 60 ° C.

The perfluoroalkyl group-containing silazane compound (specific organosilicon compound) is a mixture of a monomer (perfluoroalkyl group-containing triaminosilane) and an oligomer thereof.

<Example 2>
A test piece was prepared in the same manner as in Example 1 except that the oxygen plasma treatment step was omitted.

<Comparative Example 1>
A test piece was prepared in the same manner as in Example 1 except that hydrolyzable silane group-containing perfluoroether (KY-130, Shin-Etsu Chemical Co., Ltd.) was used instead of the silazane compound.

B. Evaluation test Each of the above test pieces was subjected to the following 1) release heat resistance test and 2) release durability test (rubbing test).

  1) Mold release heat resistance test: A test piece was placed in an oven at 300 ° C., and the contact angle after each elapsed time was measured. The contact angle was measured by a droplet method using distilled water using a contact angle meter (Kyowa Interface Chemical Co., Ltd .: CA-D type). FIG. 2 shows the test results.

  FIG. 2 shows that the silazane film of the present invention is remarkably excellent in mold release heat resistance (more than expected) as compared with the hydrolyzable silane group-containing perfluoroether-treated film of the comparative example.

  In particular, it can be seen that Example 1 subjected to the plasma treatment hardly shows a decrease in contact angle even after 24 hours, and is excellent in heat resistance for releasing.

  That is, it was confirmed that the contact angle reduction degree of Example 1 in the heat resistance test (300 ° C. × 24 h) was within 10% and the contact angle reduction degree of Example 2 was within 20%. On the other hand, in Comparative Example 1, the contact angle reduction degree was about 80% in 12 hours.

  2) Release durability test (rubbing test): Using a rubbing tester (rubbing tester), a rubbing test is performed with cotton (cotton cloth) at a load of 1 kg, and the contact angle is measured by the above method every 100 times. And up to 3000 times. FIG. 3 shows the result of the rubbing test.

  From FIG. 3, it can be seen that Examples 1 and 2 of the present invention are clearly superior in mold release durability as compared with the comparative example. In particular, it can be seen that the plasma-treated Example 1 is further excellent in mold release durability.

C. Release durability test in actual machine mold Adhesive film (Cr, film) on reactive cavity surface of stainless steel (SUS304) mold (3-inch flat mold) base material under the same conditions as above After forming a 10 nm thick film, a super hard film (Si ₃ N ₄ , 500 nm thick) is formed, and in order to transfer the anti-reflective unevenness to the molded product, nanometer-sized unevenness is required for the shaping surface. Formed in the site. The unevenness was controlled to be less than or equal to the wavelength interval in the visible range (antireflection structure).

  For example, the antireflection structure forms unevenness with a height of 160 nm at unevenness intervals controlled at intervals of 300 nm or less. The nanometer-sized unevenness forming method on these super hard films was formed by conventional dry etching after a mask (mask material: Ag).

  Then, oxygen plasma treatment (RF: 500 W, treatment time 600 s), and using a perfluoroalkyl group-containing silazane compound (“KP-801M” manufactured by Shin-Etsu Chemical Co., Ltd.), a silazane film (film thickness: 15 nm) by a vacuum deposition method. Was used as a test piece.

  The conditions for vacuum deposition are the same as in Examples 1 and 2.

  Subsequently, a molding durability experiment was performed 10,000 times under the following conditions using the actual mold prepared as described above.

Molding machine: All-electric injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd.)
Molding material: PMMA
Molding conditions: mold temperature 110 ° C, resin temperature 280 ° C, holding pressure 60mPa
The experimental results are shown in FIG. FIG. 4 shows that the reflectance characteristics of the molded product are almost the same and hardly fluctuate even if continuous molding is performed 10,000 times. This indicates that there was no deterioration of the release film (silazane film), and it was confirmed that the actual mold had sufficient release durability.

DESCRIPTION OF SYMBOLS 10 Mold 11 Mold base material 13 Intermediate film 13a Adhesion film 13b Carbide film 15 Release film (silazane film)

Claims (7)

A surface treatment mold having a silazane film on the outermost layer, at least on the shaping surface of a mold for injection molding ,
An intermediate film having nm-sized irregularities adjacent to the inside of the silazane film,
The outer side of the intermediate film is formed of a super hard film made of Si ₃ N ₄ or SiO ₂ ,
The silazane film has a film thickness of 5 to 50 nm and is composed of a polycondensation crosslinked product having a perfluoroalkyl group-containing triaminosilane represented by the following structural formula as a monomer or a main monomer, and the superhard film Chemically bonded,
C _n F _{2n + 1} C _m H _2m Si (NH ₂ ) ₃ (where n = 2 to 10, m = 1 to 4)
A surface treatment mold characterized by that. Claims wherein comprising the further contact layer on the inside of the ultra-dura, characterized in that said seal film deposition is formed in the fourth period of 4-10 transition metal or alloy thereof selected from the group of The surface treatment mold according to 1 . 3. The surface-treated mold according to claim 1, wherein the silazane film exhibits a contact angle reduction degree of 20% or less in a heat resistance test (300 ° C. × 24 h). The surface treatment mold according to claim 3, wherein the silazane film exhibits a contact angle decrease of 10% or less in a heat resistance test (300 ° C. × 24 h). The surface treatment method for a surface treatment mold according to any one of claims 1 to 4 , wherein the surface of the silazane film is subjected to oxygen plasma treatment before the silazane film is formed. Method. 6. The mold surface treatment method according to claim 5 , wherein the condition of the oxygen plasma is an RF power of 50 to 1000 W × 5 to 3600 s. 7. The mold surface treatment method according to claim 5, wherein the silazane film is formed by vacuum deposition.

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