JPH05245848A - Release film of mold and method for forming the same - Google Patents

Abstract

PURPOSE:To make it possible to apply a uniform and extremely thin fluororesin film to the surface of a mold by applying an under film to the surface of the mold and applying thereafter an amorphous fluororesin film to the surface of the under film to form a thin film. CONSTITUTION:An under film 2 comprising chemical film, etc., is applied to the surface of a mold 1 made of iron or the like. Amorphous fluororesin dissolved into fluorine-based inert liquid is applied to the upper surface of the film 2 and thereafter said liquid is dried and thermally treated to form an amorphous fluororesin release film 3. Further, when release properties of the film 3 have fallen, amorphous fluororesin dissolved in fluorine-based inert liquid is applied again to the surface of the film 3 still remaining to form an amorphous fluororesin film 4 whose release properties have been regenerated and restored. In this manner, an extremely thin, uniform film 2-4 of fluororesin material can be applied to the surface of the mold 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold release film for a mold, for example, a mold for a plastic mold, a rubber mold, a chemical product mold, and a food mold. The metal mold here is not limited to a metal mold, and includes a glass mold, a resin mold, and the like.

[0002]

[Prior art and problems] In molding of a mold such as plastic, when an adhesive force acts between the mold and the molded product and the molded product cannot be taken out properly, a liquid mold release is performed on the surface of the mold or the molded product. The application of an agent or surface treatment of the surface of a mold to deposit and form a solid film having good releasability.

For example, it has been widely used industrially to apply a liquid silicone type release agent or a fluorine type release agent to the surface of a mold by spraying or the like. However, when such a mold release agent is applied, the mold release agent is in a liquid state, so that the mold release agent causes cohesive failure at each molding. That is, part of the release agent remains on the surface of the mold, but the rest adheres to the surface of the molded product. Therefore, the following problems have occurred.

1) The mold release agent must be applied every molding or frequently, resulting in poor molding workability and high manufacturing cost. 2) The working environment of the molding factory is bad, and it has a very bad effect on both the human body and the surrounding equipment. 3) Since the mold release agent remains on the surface of the mold, the mold release agent must be burned onto the surface of the mold during repeated molding, and the mold must be maintained. 4) If the release agent adheres to the surface of the molded product, it cannot be used depending on the product. Even if it can be used, the molded product is rarely used as it is, and the surface of the molded product has to be washed since there are processes such as painting and stamping. 5) If the release agent attached to the surface of the molded product is left as it is, the molded product is deteriorated and adversely affected. 6) If the release agent is not applied uniformly, molding defects will occur.

On the other hand, as a solid film, a metal coating such as chrome plating is formed on the surface of the mold. However, when the chrome plating is applied, the throwing power of the plating is poor, and therefore it is necessary to manufacture and plate an electrode corresponding to the shape of the mold. After that, the surface of the mold is polished and finished by buffing or the like. Therefore, it is very expensive. further,
It cannot be done anywhere because it uses the toxic substance of concentrated chromic anhydride.

Further, in the case of a metal coating, the surface energy of any metal is very large, so that an oxide coating is instantaneously formed on the metal surface. The thickness and state of the oxide film differ depending on the type of metal, alloy composition, intermetallic compound and environment in which the metal is placed. When a molding material having various functional groups and poor releasability approaches such a metal surface under conditions of high temperature and high pressure, a bond due to van der Waals force occurs between the metal surface and the molded product. Therefore, it becomes difficult to release the mold.

In addition, a resin such as a silicone resin or a fluorine resin is coated on the surface of the mold as a solid film.

When the surface of the mold is coated with a silicone resin, the silicone resin has a siloxane-bonded three-dimensional structure and the terminal groups are covered with methyl groups. The methyl group at the end of the silicone resin is hydrophobic, and it is thought that it is effective for mold release, but when a silicone resin and a molding material that is easily compatible with each other come close to each other, the silicone resin surface and the molding material are still close to each other. Bonding due to Van der Waals forces occurs, making it difficult to release the mold. Therefore, the method of coating a molding die with a silicone resin as a solid film is used only in a very limited field.

On the other hand, the method of applying a fluororesin to the surface of the mold to form a solid film has a small surface energy of the fluororesin and is excellent in water repellency and oil repellency, so that good mold releasability is obtained. can get. Moreover, C which constitutes the fluororesin
Since the energy of -F bond is large, it has excellent heat resistance and chemical resistance. Therefore, it can be said that the fluororesin is the most suitable material as the mold release film of the molding die.

For example, industrially, a fluorine resin such as polytetrafluoroethylene (Teflon PTFE), hexafluoropropylene copolymer (Teflon FEP), tetrafluoroethylene, perfluoroalkyl vinyl ether copolymer (Teflon PFA) is coated. Has been done. In particular, Teflon FEP is the most suitable release coating because it has a good flowability of the fluororesin when baked and is less likely to cause defects such as pinholes in the coating.

If the surface of the mold is not directly adhered to the fluororesin, the surface of the mold is difficult to be adhered to. Therefore, the surface of the mold is roughened by shot blasting or the like, and then the primer layer is coated and then the fluororesin is coated. Further, since a fluororesin is weak against abrasion, a fluororesin containing a dispersant such as trivalent chromium is coated as an intermediate layer. Therefore, the fluororesin coating film has two layers,
It has a three-layer structure. Also, since fluororesin cannot be dissolved in a solvent, the coating method is electrostatic coating as powder, or it is applied to the mold surface after being dispersed in water containing a surfactant and then heat treated. A fluororesin coating film is formed by baking.

However, when a molded product is manufactured by coating the surface of a mold with a fluororesin as a solid film, the following problems occur.

1) The fluororesin coating film has a two-layer or three-layer structure, and since the fluororesin is coated as a powder or a dispersion liquid, the thickness of the coating film becomes large, usually 30 μm or more. For this reason, it cannot be used for a mold having a fine surface design (texture, wood grain, leather pattern, etc.) on the inner surface. When the shape of the molding die is accompanied by sharp edges and grooves, the edges and grooves are rounded, and the commercial value of the molding die is extremely reduced. In addition, the dimensional accuracy is significantly reduced.

2) The inner surface of the molding die often has a complicated shape, and it is very difficult to coat the fluororesin as a powder or a dispersion liquid. Particularly, those with a deep bottom cannot be coated with a fluororesin.

3) After applying the fluororesin on the surface of the mold,
When baking by heat treatment, it must be baked at a temperature above the melting point of the fluororesin. Teflon PTFE,
Fluorine resin of Teflon FEP and Teflon PFA is 330-4
It is baked at 00 ℃ and then slowly cooled. For this reason, many molding dies are in an annealed state, the hardness thereof is lowered, and deformation due to heat occurs. In particular, the accuracy of the parting line (divided surface) of the mold is deteriorated and the mold is deteriorated.

4) The releasability of the fluororesin coating is good at the initial stage, but as the molding is repeated, the surface of the fluororesin coating is deteriorated, the mold base and the primer layer are separated from each other, the primer layer and the fluororesin layer are separated. And peeling between the fluororesin layer and the fluororesin occur.

5) At the time of injecting the molding material and taking out the molding, a frictional force due to shear works between the fluororesin release coating and the molding material and between the fluororesin release coating and the molding, and the release coating is worn. .. In particular, when a molding material that is hard and has a poor releasability is used, or when the molding conditions are a high mold temperature and a high molding pressure, the durability of the fluororesin coating deteriorates.

6) When the fluororesin release coating reaches the end of its life, the release coating is regenerated. At that time, since the fluororesin cannot be peeled off by a chemical means, the release coating is retreated after the release coating is peeled off by a physical method such as shot blasting. At this time, the molding die is significantly damaged, and the consumption of the molding die becomes faster.

As described above, even with a solid coating of fluororesin, the fundamental problems have not been solved yet, and the present day is reached. In particular, in recent years, even though the molding material and the molding method have become complicated, the fundamental technical problem in the case of using a release solid coating for the molding die has been left unattended.

[0020]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the conventional technical problems in the case of coating the surface of a molding die with a fluororesin-based material to form a release solid coating, and in particular the following: It is an attempt to solve a problem.

1) It is possible to coat the surface of the molding die with an extremely thin and uniform film of fluororesin material, thereby dramatically expanding the range of application of the fluororesin material to the molding die as a release film. To spread. 2) Even for molds of all materials and shapes,
To be able to apply a fluororesin-based coating. 3) The reliability and stability of the coating are secured by solving the problem of peeling between the mold and the fluororesin coating, and improving the mechanical strength and wear resistance of the fluororesin coating.
Be industrially practical. 4) To solve the problem of dimensional deformation and deterioration of hardness of the molding die. 5) By chemical treatment, not by physical treatment,
To enable removal and regeneration of the fluororesin release coating on the surface of the molding die. 6) To improve the durability of the mold release film of the molding die.

[0022]

In order to solve the above problems, according to the present invention, an undercoat film on the surface of a molding die and an amorphous fluororesin having a uniform thickness adhered on the undercoat film. A mold release coating comprising a coating and a mold.

In the method for obtaining the above-mentioned release coating, an undercoat is formed on the surface of a molding die, an amorphous fluororesin dissolved in a fluorine-based inert liquid is applied thereon, and then a fluorine-based inert liquid is applied. It consists of the steps of volatilizing, drying and then heat treatment.

Amorphous fluoropolymers (amorphous fluoropolymers) have a glass transition temperature at which the micro-Brownian motion of the main chain of the amorphous part begins. A typical amorphous fluororesin is a copolymer having the structure of the following formula (1);

Various grades having different glass transition temperatures can be prepared by changing the copolymerization ratio of [perfluoro (2,2-dimethyl-1,3-diol)]. 70 ~ 350 ℃
Those having a glass transition temperature in the range of can be produced. Other amorphous fluororesins have different structures, but they are the same in that they have a cyclic structure in the main chain.

Amorphous fluororesins have hitherto been tried to be used as a contact lens or a protective film for semiconductors, but have not been tried to be used as a mold releasing material.

Fluorine-based inert liquids include perfluorocarbon liquids and perfluoroorganic compound liquids.

The perfluorocarbon liquid has the general formula C _n F
_It consists of _{2n + 2} . Hydrogen in which the terminal hydrogen of a hydrocarbon is completely replaced by fluorine, has 6 carbon atoms represented by the following formula (2).
Manufactured from:

The perfluoroorganic compound liquid has the general formula (C
_n F _{2n + 1} ) ₃ N consisting of a perfluorotrialkylamine organic compound, a typical structure of which is shown by the following formula (3);

The lower the carbon number of the fluorine-based inert liquid, the lower the boiling point and the lower the surface energy of the liquid. The higher the carbon number, the higher the boiling point, and gradually the liquid becomes a gel. Fluorine-based inert liquids currently have a boiling point of 25
It is manufactured in the range of ~ 250 ° C.

The present inventor has found that the amorphous fluororesin dissolves in the fluorine-based inert liquid in a limited amount. The lower the glass transition temperature of the amorphous fluororesin, the more the amorphous fluororesin is dissolved in the fluorine-based inert liquid, and the lower the boiling point of the fluorine-based inert liquid, the more the amorphous fluororesin can be dissolved. By heating the amorphous fluororesin or applying energy by ultrasonic vibration, the amorphous fluororesin is easily dissolved in the fluorine-based inert liquid up to about 10% by weight.

It has been found that when an amorphous fluorine resin dissolved in a fluorine-based inert liquid is applied to the inner surface of a molding die by using a brush or a spray gun, it can be applied very easily and uniformly. By applying multiple layers, a film thickness of several tens of μm or more was obtained, and by applying a solution in which the amount of amorphous fluororesin dissolved was small, it was possible to obtain an ultrathin film of several hundred liters with few pinholes. Since the surface energy of the fluorine-based inert liquid is extremely small, the wettability with the molding die is very good, and therefore thin and uniform coating is possible.

Next, when the amorphous fluororesin coated on the surface of the molding die is used as a release solid coating,
The mold base and the amorphous fluororesin must be firmly adhered. The present inventor has repeated numerous experiments and, as a result of intensive studies, thought that the amorphous fluororesin could be firmly adhered to the surface of the mold by some surface treatment. As a result, if an oxide film having a certain thickness is formed as an undercoat on the mold surface, or if an adhesion-imparting agent is coated, after applying an amorphous fluororesin, the temperature of room temperature to 360 ° C. It has been found that heat treatment at temperature achieves this end.

As for the molding die, the iron die is predominantly used, and the aluminum die is used next most. In addition, nickel type, copper alloy type,
There are zinc alloy type, stainless type, glass type, and resin type.
A suitable undercoat may be applied depending on the mold material. This has made it possible to obtain a highly accurate and durable amorphous fluororesin coating film.

Further, since the present inventor was familiar with molding technology and mold technology, it was necessary to complete the method for re-forming the release coating and to improve the durability of the release coating. I was feeling. By using the amorphous fluororesin release coating of the present invention, it was conceived that even a release coating once solidified could be dissolved and removed with a fluorine-based inert liquid, and the mold on which the release coating was actually formed was made into a fluorine-based release coating. When placed in an active liquid, only the amorphous fluororesin on the surface of the molding die is dissolved, other parts are not affected, and the amorphous fluororesin coating film can be completely peeled off chemically. It was then,
If the undercoat is destroyed, reprocess the undercoat, and if there is no damage to the undercoat, reapply amorphous fluororesin dissolved in a fluorine-based inert liquid on the mold surface. As a result, it was possible to reconstitute the release coating without damaging the mold.

When the durability of the release coating is short, even if the mold is removed from the molding machine and the release coating of the mold is reprocessed, the effort is more than expected. Therefore, improving the durability of the release coating has been an absolute theme. When the release coating of the present invention is used, for example, as compared with the conventional Teflon FEP resin release coating, although the wear resistance of the coating and the prevention of delamination are dramatically improved, the durability of the coating is The results were almost the same.

At the time of mold release, although the mold release can be carried out at the interface between the fluororesin release film and the molded product, when the surfaces thereof are observed microscopically, the release film and the surface of the molded product also show cohesive failure. It is more natural to think that is peeled off. It is very difficult to make the release coating semi-permanent because the adhesion phenomenon is a phenomenon in which a plurality of complicated factors act to bond the partner to each other. The release coating of the present invention is no exception, and its life is equivalent to that of conventional fluororesins.

Therefore, the present inventor applies the amorphous fluororesin dissolved in the fluorine-based inert liquid to the surface of the amorphous fluororesin coating film, and volatilizes and drys the fluorine-based inert liquid. It was found that the crystalline fluororesins were compatible with each other and adhered and solidified. That is, a release coating is prepared by coating an amorphous fluororesin dissolved in a fluorine-based inert liquid with a spray or the like on the release coating with reduced release ability, and then drying the fluorine-based inert liquid. It was found that the remolding of the resin gives the same mold releasing ability as that of the first coating, and can be used for a long time in the subsequent molding. As a result, all the drawbacks of the conventional fluororesin release coating were solved and the present invention was completed.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific means for carrying out the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a molding die (female mold) provided with a release coating of the present invention. Explaining the step of forming the coating, first, the base coating 2 is applied to the surface of the molding die 1. The material of the mold 1 is iron, aluminum, nickel, copper alloy, zinc alloy, stainless steel, glass or the like. Examples of the base coating 2 include a chemical conversion coating, an anodized coating, a self-generated oxide coating, a metal oxide plating coating, and a coating of a silane coupling agent or a titanate coupling agent which is an adhesiveness-imparting agent.

In order to form a chemical conversion film, the mold is pretreated, then immersed in a treatment liquid having a raised temperature, and then dried. In the case of an iron mold, a phosphate treatment, a chromate treatment, an oxalate treatment, an iron oxide treatment method, etc. may be mentioned. Particularly, the phosphate treatment is a powerful means, and an iron phosphate coating, a zinc phosphate coating, a zinc calcium phosphate coating, a manganese phosphate coating, etc. can be obtained. In the case of a die made of aluminum, there are an extremely large number of treatment methods such as a treatment method mainly containing sodium carbonate or sodium chromate, or a treatment method mainly containing chromic acid or phosphoric acid. For zinc alloys, there are chromate treatment and phosphate treatment. In the case of a copper alloy, there are a chromic acid treatment method and a copper oxide treatment method. In the case of stainless steel, there is an oxalate film formation method.

The thickness of the chemical conversion coating is preferably 0.1 to 1 μm, and if it is too thick, the chemical conversion coating itself is not a strong coating and becomes brittle. Durability will deteriorate.

To form an anodized film, the mold is pretreated, then immersed in a treatment solution, and the mold is used as an anode to apply a voltage, whereby an oxide film is formed while oxygen is generated in the anode. .. Aluminum anodic oxide coatings are industrially developed. Typical examples thereof include the chromic acid method, the sulfuric acid method, and the oxalic acid method. For copper alloys, nickel, iron and zinc alloys, an anodized film is formed by anodizing the mold by immersing it in a caustic soda solution. The anodic oxide coating has high film strength and good adhesion with the amorphous fluororesin.

The self-generated oxide film utilizes that the oxide film is naturally formed on the metal surface. Depending on the material of the mold, or when the surface of the mold is rough, the amorphous fluororesin adheres to the surface of the mold only to the extent of degreasing. However, it is more effective to prevent rust by providing some other undercoat on the autogenous oxide coating, and the durability of the release coating is also improved.

The metal oxide plating film is obtained by plating with a mold as a cathode. This is a special method in the field of plating, and it may be difficult to plate when the inner surface shape of the die is complicated. However, since the film strength and heat resistance of the metal oxide plated film are extremely good, it is considered to be effective when the die shape is simple and the durability of the undercoat film is desired. Examples of the metal oxide plating film include a black chrome plating film.

It is the most effective means of the present invention to use the silane coupling agent-treated coating which is an adhesion-imparting agent as the undercoat. Since many molding dies are heavy and heavy, it takes a lot of work to immerse them in the solution.
This is because there is a demerit that metal corrosion is likely to occur when immersed in the treatment liquid. In the silane coupling agent treatment, after degreasing the mold surface, an aqueous solution of the silane coupling agent is applied by brush onto the mold surface. Next, the mold is heated and dehydrated, and then an amorphous fluororesin is applied. In other words, the equipment can be obtained by a series of steps and the equipment is simple, and the adhesive force is remarkably effective. Table 1 exemplifies typical silane coupling agents.

[0047]

The use of a coating film treated with a titanate coupling agent, which is an adhesion-imparting agent, as the undercoating film is also a powerful means as with the silane coupling agent. Table 2 illustrates representative titanate coupling agents.

[0049]

In addition to the above, the adhesiveness-imparting agents include organic phosphorus compound-based adhesiveness-imparting agents, silyl peroxides, alkyleneimines, and the like, and have the same effect.

After applying the above-mentioned base film 2 to the mold 1, an amorphous fluororesin dissolved in a fluorine-based inert liquid is applied thereon, and then the fluorine-based inert liquid is dried and further heat treated. Thus, the amorphous fluororesin release coating 3 is obtained.

When the fluorine-based inert liquid has a low boiling point, it is easy to dissolve the amorphous fluororesin, but the solution is not so viscous and the fluorine-based inert liquid evaporates immediately. It is difficult to form a coating film uniformly. On the other hand, when the fluorine-based inert liquid has a high boiling point, it is difficult to dissolve the amorphous fluororesin, so it takes time and effort to increase the thickness of the coating film of the amorphous fluororesin. Therefore, it is preferable to use a fluorine-based inert liquid having a boiling point in the range of 100 to 180 ° C.

If the glass transition temperature of the amorphous fluororesin is too low, the molding die is in a high temperature state, so that the amorphous fluororesin becomes rubber-like and the strength of the release coating is lowered. Therefore, it is preferable to use an amorphous fluororesin having a glass transition temperature higher by about 10 ° C. than the upper limit of the temperature of the mold surface when the mold is continuously used.

When the amount of the amorphous fluororesin dissolved in the fluorine-based inert liquid is about 1 to 3% by weight, the coating is easy. If the amount of dissolution is too large, it becomes agar and difficult to apply.

The simplest method for applying the amorphous fluororesin dissolved in the fluorine-based inert liquid onto the undercoating film is to apply it uniformly using a brush and then apply it overcoating. Further, spin coating, dip coating, spray coating and the like are effective means for obtaining a thin and uniform release coating. The temperature of the solution when applying it may be room temperature, but 30-60
It is preferable to warm to about ° C. Especially in the case of an amorphous fluororesin having a high glass transition temperature, a gel is formed at room temperature, so it is better to heat it. On the other hand, the temperature of the molding die may be room temperature or may be heated to about 30 to 60 ° C.

In order to volatilize the fluorine-based inert liquid to dry the coating, any of natural drying, heating, or vacuuming may be used, but it is better not to perform forced drying too rapidly.

The amorphous fluororesin coating adheres well to the undercoat by heat treatment at about 100 ° C. after drying, but in order to complete the adhesion, heating at 200 to 350 ° C. for about 1 hour in a furnace. Treatment is preferred.

When the releasing ability of the amorphous fluororesin coating film 3 coated on the mold 1 is lowered, the amorphous fluororesin dissolved in the fluorine-based inert liquid is replaced with the remaining amorphous fluororesin. When the coating is applied again on the coating 3 with a spray or a brush, an amorphous fluororesin coating 4 which has been re-formed to recover the releasing ability is obtained. At this time, the concentration of the amorphous fluororesin in the solution is preferably about 0.5 to 3% by weight.

The temperature at the time of this recoating is preferably from room temperature to about 70 ° C. After re-coating, if the coating film is in a state where the coating film is still dry, the release coating film will be destroyed if it is moved to the molding step. Therefore, it is better to dry the coating film sufficiently. Preferably, coating is carried out at a mold temperature of 30 to 50 ° C., then the mold temperature is raised to the upper limit temperature of the molding conditions (that is, after one-time baking), and then the molding step is carried out. The re-formed release coating is
It can be used for a long time in the subsequent molding, and the durability of the release coating can be dramatically improved by repeating the regeneration.

Since the molding material adheres to the release coating after the release, it may be necessary to remove the coating once and then re-form the coating. In such a case, the molds to which the release coatings 3 and 4 are attached are put in a fluorine-based inert liquid and heated to 30 to 50 ° C. to easily remove the coatings 3 and 4. be able to. At this time, if the base coating 2 is not damaged, the release coating 3 is re-formed by applying an amorphous fluororesin dissolved in a fluorine-based inert liquid on it. When the adhesive effect of the base film 2 is lost or some damage is caused, an adhesive agent may be applied and dried, and then an amorphous fluororesin dissolved in a fluorine-based inert liquid may be applied. The release coating 3 can be regenerated.

Further, boron nitride in amorphous fluororesin,
Dispersion of about 10% by weight of a hard material such as molybdenum disulfide, silicon carbide, graphite, graphite fluoride, or glass fiber is effective in improving wear resistance.

Furthermore, when an adhesion-imparting agent is added to the amorphous fluororesin, the degree of adhesion of the release coating to the base coating is further improved.

Example 1 A block (width of the bottom 70 × 70 mm, height 50 mm) obtained by cutting S50C steel material into a shape as shown in FIG. 1 was used as a sample of a molding die, and a treatment step A and a treatment step shown below were performed. B
The surface of the block was coated with an amorphous fluororesin release coating. AF-1 as amorphous fluororesin in each process
600 (glass transition temperature: 160 ° C.) is used as perfluoride 1L-260 (boiling point: 160 ° C.) as the fluorine-based inert liquid.

[0064]

[0065]

Prototype mold No. 1 of the present invention according to processing step A
(Average film thickness 5 μm) and trial mold No. 2 (average film thickness 5 μm) of the present invention by the process B, and conventional Teflon F
The molding of the rubber material was repeated using a trial mold No. 3 (average film thickness 20 μm) in which the EP resin release coating was applied to the same block surface as above. Molding material is polybutadiene 10
It was composed of 0 parts by weight, 30 parts by weight of zinc acrylate, 20 parts by weight of zinc oxide, and 2.0 parts by weight of dicumyl peroxide, and pressure-molded at 160 ° C. for 30 minutes per molding.

As a result, for the prototype die No. 1, 20
It was possible to take out during molding 0 times, but then taking out became difficult. Therefore, Perfrod 1L-260
A 1% by weight solution of AF-1600 dissolved in was applied with a brush and then dried to reprocess the release coating. Then 10
It could be taken out during molding 0 times. Then do the same second re-treatment, so that while molding 100 times,
It was confirmed that it could be taken out. Further, the same third reprocessing was performed, and thereafter, it was possible to take out during molding 100 times.

The trial mold No. 2 could be taken out even after molding 200 times. Then, a 1% by weight solution of AF-1600 dissolved in Perflude 1L-260 was applied with a brush and then dried to reprocess the release coating.
After that, it was possible to take out during molding 100 times. Then, the same second reprocessing was performed, and as a result, it was confirmed that the product could be taken out during 100 moldings. Further, the same third reprocessing was performed, and thereafter, it was possible to take out during molding 100 times.

With respect to the trial mold No. 3, it was possible to take out during the molding of 200 times, but the taking out became difficult thereafter. And it was impossible to take out after molding 220 times.

After the trial molding, the molding material adhered on the mold release film, so that the film was tried to be removed and reformed. That is, the prototype dies No. 1 and No. 2 were immersed in a caustic potash 30g / l solution (80 ° C) for 10 minutes, washed, and then immersed in a Fluorinert FC-75 solution (70 ° C) manufactured by Sumitomo 3M Ltd. for 30 minutes. The coating was dissolved by immersion and removed. Then, perflord 1L
-The coating was regenerated by applying a 3% by weight solution of AF-1600 dissolved in 260, drying and heat treatment.

The coating film of the trial mold No. 3 could not be chemically peeled off.

Example 2 A substrate made of a high-purity aluminum material, a pure nickel material, and a glass material, the surface of which was finished as smooth as possible (3 cm square,
Thickness of 1 mm) is prepared, and the seven processing steps C to I shown below are provided.
The surface of the substrate was coated with an amorphous fluororesin release coating. The “amorphous fluororesin” in the treatment steps D to I is
Similar to treatment step C, it is a 1% by weight solution of AF-1600 dissolved in Perflude 1L-260.

[0073]

[0074]

[0075]

On each of the sample substrates No. 1 to 7 having the release coating formed by each of the above-mentioned treatment steps C to I, a plate of Himilan H-1705 resin (manufactured by Mitsui DuPont Polychemical Co., Ltd.) as a molding material ( (3 cm square, thickness 2 mm) was placed and heated in an electric furnace at 190 ° C. for 30 minutes. When the Himilan resin was in a molten state, a wire was placed in the resin, and the wire was fixed by cooling to room temperature, and the Himilan resin was adhered onto the release coating. Next, in order to measure the adhesive strength between the release coating and the resin, weights of various weights were hung on the wire, and the weight when peeling between the release coating and the resin was converted to tensile strength was measured. It was After the peeling, the operation of re-bonding the high milan resin and then measuring the tensile strength was repeated.

Also, an aluminum substrate, a nickel substrate,
The adhesive strength between the substrate and the resin was also measured in the same manner for each of the glass substrate and the glass substrate directly bonded with the high-milan resin without the release coating.

The results are shown in Table 3. The unit of tensile strength shown in the table is g / cm ² .

[0079]

In Table 3, the symbol "X" indicates that the film was not peeled off even when a tensile strength of 3000 g / cm ² or more was applied, and the subsequent measurement could not be performed.

As shown in these results, the mold releasing property of the present invention is extremely good by applying the mold releasing film of the present invention, and the mold releasing film of the present invention is more releasable than the case of not applying it. It will be good.

[0082]

The following effects can be obtained by applying the release coating of the present invention to a molding die.

1) The surface of the molding die can be coated with an extremely thin and uniform fluororesin coating. As a result, the range of applications of fluororesin as a mold release coating for molding dies has expanded dramatically. .

2) It is said that the conventional fluororesin coating cannot be applied to the glass mold and the resin mold because of its extremely poor adhesion, and the applicable mold shape is also limited. . However, according to the present invention, it is possible to apply a fluororesin coating to a molding die of any material or shape.

3) By providing an undercoating by surface treatment, peeling of the fluororesin release coating from the mold is prevented.

4) By using the amorphous fluororesin, the hardness of the coating was increased, and the mechanical strength and abrasion resistance of the coating were improved.

5) It became possible to lower the baking temperature of the fluororesin onto the mold by about 50 to 380 ° C. as compared with the conventional case, and the problems of mold deformation and hardness deterioration were solved.

6) The reliability and stability of the release coating are improved,
It became industrially practical.

7) Conventionally, ultrasonic waves, water jet, etc. were used as physical methods when peeling off the coating film to re-form the release coating film, but all have been industrially successful. There wasn't. As a chemical method, it was attempted to dissolve the primer layer under the fluororesin film with a strong alkali or strong acid to float the fluororesin film and peel it off, but it took days, and the mold was corroded. As a result, it was not industrially successful. However, according to the present invention, it becomes possible to easily remove and re-form the fluororesin release coating on the surface of the molding die by chemical treatment.

8) The precision and durability of the release coating are improved and the re-forming is facilitated, so that the quality of the molded product is improved and the manufacturing cost is reduced.

9) Since both the amorphous fluororesin and the fluorine-based inert resin are highly safe chemicals and the treatment method for forming the undercoat is also safe, the safety of the operator and the environment The destruction problem is solved.

10) The formation and re-treatment of the release coating can be performed in a series of steps, the equipment is simple, and energy is saved.

11) When manufacturing a plastic lens, a glass mold is used, and a resin is poured into the glass mold and polymerized for a whole day and night to perform molding. When the molded product was taken out, the mold releasability was poor, so the mold was easily cracked or the resin was easily attached to the mold. However, according to the present invention, it becomes possible to coat the glass mold with a high-precision coating having a good releasability, and the consumption of the glass mold can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a molding die provided with a release coating.

[Explanation of symbols]

 1 Molding die 2 Undercoat 3, 4 Release film

Claims (9)

[Claims] 1. A base film on the surface of a molding die, and an amorphous fluororesin film adhered on the base film.
Release film for molding dies. 2. The release according to claim 1, wherein the undercoat is a film selected from a chemical conversion film, an anodized film, a self-generated oxide film, a metal oxide plating film, and an adhesion promoter film. Mold coating. 3. The release coating according to claim 1, wherein the amorphous fluororesin has a glass transition temperature of 70 to 350 ° C. 4. An undercoating film is formed on the surface of a molding die, and an amorphous fluororesin dissolved in a fluorine-containing inert liquid is applied thereon, and then the fluorine-containing inert liquid is volatilized and dried, and then heated. A method for forming a release coating on the surface of a molding die, which comprises treating. 5. The undercoating film is a film selected from a chemical conversion film, an anodized film, an autogenous oxide film, a metal oxide plating film, and an adhesion promoter film.
The method described in. 6. The method according to claim 4, wherein the fluorine-based inert liquid has a boiling point of 25 to 250 ° C. 7. The method according to claim 4, wherein the amorphous fluororesin has a glass transition temperature of 70 to 350 ° C. 8. When it is necessary to replenish the release coating on the surface of the molding die according to claim 1, an amorphous fluorocarbon resin dissolved in a fluorine-based inert liquid is applied to the surface of the release coating. A method for forming a release coating on the surface of a molding die, which comprises re-forming the release coating by drying and then drying. 9. The amorphous fluororesin film on the surface of the mold is washed with a fluorine-based inert liquid when the release film on the surface of the molding die according to claim 1 needs to be removed and reformed. After the solution is removed by dissolving, the amorphous fluororesin dissolved in the fluorine-based inert liquid is applied on the base film on the mold surface, and then the fluorine-based inert liquid is volatilized and dried, and further heat treated. The method of forming a release coating on the surface of a molding die, comprising re-forming the release coating.