JPH07186157A - Mold for resin molding and its preparation - Google Patents

Abstract

PURPOSE:To shorten cycle time and to improve accuracy of processing by providing a carbon layer deposited on the base material of a mold and a fluorinated layer formed on the surface part of this carbon layer so as to make a covalent bonding with the carbon. CONSTITUTION:A carbon layer 2 is provided on the molding face of the base material 1 of a mold. As the carbon film 2 is provided by depositing, sputtering, CVD, etc., the adhesiveness between the base material 1 of the mold and the carbon film 2 is extremely high. In addition, as it can be made very thin and uniform, the shape of the molding face of the mold is hardly changed, good transfer to a resin can be performed. This mold is heated under vacuum and a fluorogas is introduced into the mold. As the introduced fluorogas is extremely reactive, it reacts with the carbon to form a compd. contg. a covalent bonding C-F. The surface of the carbon film is covered with a fluorinated layer 3. As the carbon film 2 is formed into a film by using carbon directly to the base material 1 of the mold by means of PVD, CVD etc., high adhesiveness between the carbon film and the base material of the mold can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die for molding a resin and a method for producing the same.

[0002]

2. Description of the Related Art When molding a resin, it is required that the molded resin be easily released from the mold. For this reason, JP-A-60-73816 and JP-A-61
No. 16823 discloses that a mold is provided with a non-adhesive layer such as a release agent. Specifically, the non-adhesive layer is formed by applying a release agent to the mold by dipping, spraying, spinning or brush coating, or baking and coating a fluororesin.

On the other hand, it is also practiced to add a release agent to the inside of the resin to be molded without attaching the release agent to the mold.

Further, as a method of releasing a resin without using a releasing agent, Japanese Patent Laid-Open No. 546006 discloses a method of giving a temperature difference between a resin and a mold and utilizing a difference in coefficient of thermal expansion. As described in JP-A-60-76319, a method is described in which an ultrasonic vibrator is brought into contact with the resin and the mold in close contact with each other to cause ultrasonic vibration.

[0005]

However, any of the conventional techniques has the following drawbacks. JP-A-60
In the method of applying the release agent described in JP-A-73816 to the entire molding surface, the release agent and the surface of the mold are not sufficiently adhered to each other, or the bonding force between the release agent molecules or in the molecule is insufficient. Therefore, by repeating the mold release, the release agent layer itself is broken or peeled from the mold substrate, the release agent is transferred to the resin, and the non-adhesiveness of the surface is deteriorated with time. This allows
Since it must be reprocessed as needed or periodically, the production efficiency is reduced and it is necessary to prepare many molds. In the specification of the publication, it is described that the mold release can be performed three times, but such a number of times cannot be applied to the molding field for mass production.

The same is true of JP-A-61-16823, and even if a fluororesin having excellent non-adhesiveness is fixed on the surface of the mold base with an organic binder, the organic binder has good adhesion to the mold base. When an excellent binder is used, the adhesion with the fluororesin deteriorates.On the contrary, when an organic binder having excellent adhesion with the fluororesin is used, the adhesion with the base material deteriorates. In terms of being insufficient. In addition, since such a release layer has a very large film thickness of several tens of μm or more, there is a problem that the accurate shape of the die molding surface cannot be transferred to the resin.

On the other hand, in the method of adding the release agent to the resin, the amount of the release agent that actually contributes to the release is small, so that it is necessary to add a large amount, which causes the modification of the resin and the mold release. There are problems such as pollution.

The method described in Japanese Patent Application Laid-Open No. 54-6006 has the drawback that it takes a long time to give a temperature change and the molding cycle time becomes long. Similarly, the method described in Japanese Patent Application Laid-Open No. 60-76319 is used. The method described in the publication also has a drawback that the molding cycle time becomes long. In addition, these methods also have the disadvantage that the molding apparatus must have a complicated mechanism.

The present invention has been made in consideration of these problems of the prior art, and does not lengthen the cycle time, does not deteriorate the processing accuracy, and even when several thousand or more are continuously molded. An object of the present invention is to provide a resin molding die that can be continuously and easily released from the mold, and a method for producing the same.

[0010]

MEANS FOR SOLVING THE PROBLEMS AND ACTION The resin molding die of the present invention is formed so as to covalently bond with the carbon layer vapor-deposited on the mold base material and the carbon on the surface portion of the carbon layer. And a fluorinated layer. The method for producing this mold comprises the steps of depositing a carbon layer on a mold base material, and fluorinating the surface of the carbon layer to form a fluorinated layer that is covalently bonded to carbon on the carbon layer surface. It is characterized by having.

In this method, the carbon layer is formed by physical vapor deposition,
Any of chemical vapor deposition may be used, and further vapor deposition may be performed by sputtering or plasma CVD. Further, in the step of fluorinating, after the carbon layer is provided in vacuum, heating may be performed while maintaining the vacuum, and the fluorine gas or the fluorinated gas may be directly introduced into the vacuum. As these gases, F ₂ , HF and the like are used, but F ₂ is particularly preferable.

FIG. 1 shows a cross section of a molding die of the present invention.
The carbon layer 2 is provided on the molding surface of the mold base 1. Since this carbon film 2 is provided by vapor deposition, sputtering, CVD or the like, it has extremely high adhesion to the mold base 1. Further, since it is extremely thin and can be uniformly provided, the shape of the molding surface of the mold is hardly changed, and good transfer to the resin can be performed.

This mold is heated in vacuum and fluorine gas is introduced. Since the introduced fluorine gas is very rich in reactivity, it reacts with carbon to generate a compound containing a covalent bond C-F. As a result, the surface of the carbon film is fluorinated layer 3
Will be covered with. As the compound having a C—F bond, a fluororesin (PTFE (polytetrafluoroethylene,
Trade names include Teflon), PFA, CTFE, etc.), graphite fluoride (CF ₂ , CF ₃ ), etc., but these compounds are all chemically stable, and due to the characteristics of fluorine that reduce the surface energy. It has high releasability and water repellency.

The C--F bond has a high bond strength, is thermally stable, and has high durability. For example, the adhesion between ordinary adhesives and organic binders, and the intermolecular force (van der Waals force) that governs strength are 21 KJ / mol.
On the other hand, the covalent bond energy of C-F is about 4
It is 19 KJ / mol, which is a very strong bond.

On the other hand, since the carbon film 2 is formed by depositing carbon directly on the die base material 1 by PVD, CVD or the like, high adhesion between the carbon film and the die base material can be obtained. . Moreover, the carbon film itself has high durability due to the high bond energy of C—C and C = C (about 335 and 460 KJ / mol, respectively).

From the above, the surface layer having high releasability can be provided on the substrate with high adhesion. Further, since the surface of the mold is completely covered with the chemically stable film, it is possible to prevent corrosion of the mold due to decomposition gas generated by reaction or decomposition of the resin during resin molding.

When fluorinating while maintaining the degree of vacuum at the time of forming the carbon film, the entire surface is not oxidized even if the carbon film is exposed to the atmosphere, but the oxidized part is stable (the binding energy is about (335 KJ / mol), it cannot bond with fluorine, and the fluorine concentration on the surface is slightly lowered, but this does not occur. As a result, a releasable surface having particularly excellent performance can be obtained.

[0018]

【Example】

(First Embodiment) FIG. 2 shows a first embodiment of the present invention.
And FIG. 4 shows a cross-sectional view of the molding process. Molds 4,5 with PD555 (made by Daido Steel Co., Ltd.) equivalent to SKD12
To form. The mold 4 is fixed, the mold 5 is held so as to be movable up and down, and the mold release surfaces 6 are provided on the molding surfaces of the molds 4 and 5. To form the releasable layer 6, carbon is first deposited on the surfaces of the molding surfaces of the molds 4 and 5 by vapor deposition. After that, the mold is transferred to a vacuum container, and the inside of the container is sucked to obtain 6.65 × 10 ⁻⁴ P.
Hold at pressure a. Next, the mold is heated to about 400 ° C., and when the temperature is stable, fluorine gas (F ₂ ) is added to 10
The pressure is introduced up to 1 KPa, and the pressure of the fluorine gas in the system is kept at 101 ± 1 KPa for 60 minutes for fluorination.

In the above structure, a carbon film is vapor-deposited on the surface of the mold, and the outermost surface thereof is a layer having a C--F bond which is fluorinated by highly reactive fluorine gas. Since such a surface has a high mold release property and a high adhesiveness with the mold base material, it acts as a highly durable mold release layer.

The resin molding process will be described below with reference to FIGS. 3 and 4. Product name "Shirasucon RTV7" on the mold 4
500 "and" Shirasucon CAT "(manufactured by Dow Corning Co., Ltd.) were stirred at a ratio of 10: 1, a silicone resin was dropped, and the mold 5 was lowered so as to be pressed against the mold 4.
It hardens in time and raises the mold 5. At this time, the cured product was easily released from the mold, and the mold releasability did not change even after repeating molding 1000 times.

Therefore, since the mold releasing can be performed easily and repeatedly, maintenance of the mold is not required and the productivity is greatly improved. Further, even in the case of molding a resin having not so high strength, the resin molded article is not damaged because the adhesion to the mold is low. In addition, when a dummy sample in which a mold release film was similarly provided on a disk of the same material as the mold was evaluated by XPS, fluorine and some oxygen could be detected, and in the depth profile, it was fluorinated to a depth of about 60 mm. It had been.

(Second Embodiment) This embodiment will be described with reference to FIG. The mold release layer 6 according to the present invention is provided on the molding surfaces of the molds 4 and 5. In addition, a grain pattern is formed on the surface of the mold for design purposes.

The mold-releasing layer 6 is formed by forming a carbon film on the surface of the molding surface of the mold under vacuum (6.65 × 10 ⁻⁴ Pa) by sputtering, and keeping the inside of the sputtering apparatus in vacuum as it is. The mold is heated to about 450 ° C, and when the temperature is stable, fluorine gas (F ₂ ) is introduced up to 101 KPa, and the pressure of the fluorine gas in the apparatus is 101 ± 1K.
It is carried out by holding at Pa for 30 minutes.

Also in this embodiment, as in the first embodiment, a mold-releasing film is provided on the mold surface. In this example, the surface of the carbon film provided by sputtering is
Since it is fluorinated without being exposed to the air, the carbon film is not oxidized and fluorination is not hindered. Therefore,
Efficient and higher mold releasability can be provided.

The resin molding process will be described below with reference to FIGS. 3 and 4. Epoxy resin “Cemedine 15” on the mold 4.
65 "and" hardener D "(Cemedine Co., Ltd.) 10: 1
The mixture stirred at was dropped, and the mold 5 was lowered so as to be pressed against the mold 4. Then, the mold 5 was cured at 100 ° C. for 2 hours.
Raise. At this time, the cured product is easily released from the mold,
The mold releasability did not change even after 1,500 times of molding was repeated. The surface had a grain pattern transferred from the mold. In addition, when a dummy sample in which a mold-releasing film was similarly provided on a disc made of the same material as the mold was evaluated by XPS, fluorine could be detected and oxygen could hardly be detected.

This embodiment like this operates in the same manner as the first embodiment, but in this embodiment, even if the resin is bitten on the surface of the mold and it is difficult to release the mold, the mold can be easily released. ing. As a result, various designs can be expressed on the surface of the resin molded product, and added value such as improvement in appearance and touch can be increased.

(Third Embodiment) FIG. 5 shows a third embodiment of the present invention, in which a fixed mold 11 having a gate 14 and a movable mold 1 are provided.
The mold release layer 13 is provided on the second molding surface. In the molding of the releasable layer 13, first, a carbon film is deposited on the molding surface of the mold by CVD. After that, transfer to a vacuum container,
After sucking the inside of the container into a vacuum, heat the mold to about 450 ° C, and when the temperature stabilizes, pressurize the fluorine gas at 101K.
The pressure of fluorine gas in the system is set to 1 as it is by introducing up to Pa.
The carbon on the surface of the carbon layer is fluorinated by holding at 01 ± 1 KPa for 60 minutes. In this embodiment, since the carbon film forming the releasable film is formed by CVD, the carbon film can be easily attached even in a complicated die shape, and the carbon film can be provided on the necessary whole surface.

The fixed mold 11 and the movable mold 12 thus obtained were injection-molded with a thermoplastic resin. As the resin, PC (H-3000: Mitsubishi Gas Chemical Co., Inc.) was used. As a result of molding for about 100,000 shots, the molded product was easily released from the mold, and there was almost no seizure on the mold or stain on the mold.

The present embodiment as described above shows that the durability of the film and the releasability of the film sufficiently act even on the injection molding, and the easy releasability is possible. In addition, since the mold life is extended, the mold cost per product can be reduced.

(Fourth Embodiment) FIG. 6 shows a fourth embodiment of the present invention, and FIGS. 7 and 8 show a molding process of a composite optical element. A mold 21 made of PD555 is held so as to be movable up and down, and a mold-releasing film 22 is provided on its molding surface by the same steps as in the first embodiment. A glass base material 23 (hereinafter referred to as a base material) which is spherically polished on the same axis is disposed below the mold 21. A urethane acrylate-based ultraviolet curable resin 24 (hereinafter referred to as a resin) is interposed between the mold 21 and the base material 23. Mold 21, base material 23
The resin 24 is in a close contact state, and the stopper 2 with which the outer peripheral portion of the base material 23 abuts above the outer peripheral portion of the base material 23.
5 are provided.

The molding process will be described below with reference to FIGS. 7 and 8. First, as shown in FIG. 7, a required amount of resin 24 is discharged onto the upper surface of the base material 23 formed of the optical glass material BK7. On the upper surface of the base material 23, 1% by weight of a silane coupling agent KBM-503 (trade name: manufactured by Shin-Etsu Chemical Co., Ltd.) was added with ethanol to improve adhesion with the resin 24.
It is previously treated with the liquid diluted to 1, and then dried at 100 ° C. for 5 minutes.

Next, the metal mold 21 is lowered and brought close to the base material 28 to spread the resin 24, and the resin 24 is stopped at a position where the resin 24 has a desired thickness. At this time, the discharge amount is determined so that the outermost peripheral portion of the resin 24 is equal to or larger than the optically effective diameter of the molding surface of the mold 21 and does not protrude from the mold. In this state, ultraviolet rays are irradiated from below the base material 23 to cure the resin 24. Thereby, the mold 21, the base material 23, and the resin 24
To form a close contact body (see FIG. 6).

After that, by raising the die 1,
The outer peripheral portion of the base material 23 contacts the stopper 25. As a result, stress concentration occurs at the portion of the outermost peripheral portion of the resin 24 closest to the stopper 25. Here, since the mold molding surface has a high mold releasability, the composite type optical element, which is an adherent body of the base material 23 and the resin 24, is easily and instantly released from the mold 21 (see FIG. 7).

According to the present embodiment as described above, it is possible to easily release several thousand or more molds continuously without applying a mold release agent or a special mechanism.

On the other hand, as a comparative example of the first and second embodiments,
When a similar molding was performed using a mold whose molding surface had not been subjected to a mold release treatment, the adhesion between the mold and the resin was large, and if the mold was forcibly released, the resin molded product was damaged. .

Further, as a comparative example of the first and second embodiments,
Using a mold that has been subjected to a fluorine-based baking type release agent treatment on the molding surface, the same molding was performed, and when several molded products were obtained, the adhesion between the mold and the resin increased, If the mold was forcibly released, the molded product was damaged.

Next, as a comparative example of the fourth embodiment, a similar mold, base material and resin adherent was formed on the outer periphery of the optical effective diameter using a mold treated with a fluorine-based release agent, As a result of performing mold release using a similar stopper, easy mold release was not possible after about several dozen pieces, and the lens base material was damaged, which made mold release impossible.

Although silicone resin, thermosetting epoxy resin, and UV-curable urethane acrylate resin are used as the resin in each of the above embodiments, the present invention is not limited to this, and other thermosetting resins (for example, urethane and phenol) are used. , Urea resin) and ultraviolet or electron beam curable resins (epoxy acrylate, ester, ester acrylate, enthiol, urethane, etc.) and other energy curable resins can be used. Further, as the die base material, stainless steel, various tool steels, and die steels can be used depending on the application. Further, the mold shape and the like are not limited to those of each embodiment, and more complicated shapes, leather grain patterns,
It is also possible to add various designs such as letters and marks to the surface of the mold.

[0039]

As described above, according to the present invention, easy mold release can be continuously performed even when molding a large amount, and it is not necessary to repeatedly perform the mold release treatment. Further, since it is not necessary to apply a long-term external load such as a temperature change or ultrasonic waves for each molding, the molding cycle time can be shortened and the molding equipment can have a simple structure.

[Brief description of drawings]

FIG. 1 is a sectional view of a basic configuration of a molding die of the present invention.

FIG. 2 is a sectional view of the first embodiment.

FIG. 3 is a sectional view showing molding according to the first embodiment.

FIG. 4 is a sectional view showing molding according to the first embodiment.

FIG. 5 is a sectional view of the third embodiment.

FIG. 6 is a sectional view of a fourth embodiment.

FIG. 7 is a sectional view showing molding according to a fourth embodiment.

FIG. 8 is a sectional view showing molding according to a fourth embodiment.

[Explanation of symbols]

 1 type base material 2 carbon layer 3 fluorinated layer

Claims (3)

[Claims] 1. A resin molding, comprising: a carbon layer deposited on a mold base; and a fluorinated layer formed so as to covalently bond with carbon on a surface portion of the carbon layer. Mold. 2. A step of depositing a carbon layer on a mold substrate,
And a step of forming a fluorinated layer that covalently bonds with carbon on the surface of the carbon layer by fluorinating the surface of the carbon layer. 3. A method of depositing a carbon layer on a mold base material in a vacuum, heating the mold base material while maintaining the vacuum state, and introducing a fluorine gas or a fluoride gas into the vacuum. The method for producing a resin molding die according to claim 2.