KR920002405B1 - Molding graphite die for plastic or ceramic articles - Google Patents

Abstract

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Description

Graphite dies for molding plastic or ceramic products

1 is a cross-sectional view of an example in which a molding die according to the present invention is applied to an injection molding machine.

2 is a cross-sectional view of an example in which the die according to the present invention is applied to an upper die die for compression molding.

3 is a sectional view of principal parts of a graphite die for plastic molding having a reinforcing material, and an injection molding machine including the same.

4, 5 and 6 show aspects of repairing a molding die according to the present invention.

* Explanation of symbols for main parts of the drawings

20: graphite die 21: fixed die

22: moving die 23: molding cavity

25: reinforcing member 26: repair material

27: adhesive

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to molding dies used for extruding films, sheets, pipes, etc. of plastics and ceramics or for injection molding complex articles of plastics and ceramics.

Plastics are generally materials having various characteristics such as light weight, economical efficiency, processability, and corrosion resistance, and are widely used in all kinds of industrial applications such as electricity, machinery, and automobiles to daily necessities. In forming these various plastic products, a die made of a metal material of iron and its alloy is generally used.

The die (hereinafter referred to as a die) produced by a different kind of metal material has a requirement that the die material is a metal from the viewpoint of die life when the molding water is extremely large. However, in the recent trend of small quantity batch production, the necessity of preparation of dies increases, the conventional mold is excessive quality, and ① the price of the product is increased due to the increase of the mold price in the molded product. It is raising. ② The production of the mold had a drawback that required a great deal of time and reaction.

Thus, the inventors of the present invention have disclosed in Japanese Patent Application Laid-Open No. 63-162205 and the like regarding a die using a graphite material having a good high sensitivity and high density of die polishing finish surface as a die material replacing metal. There are various suggestions. In achieving the proposed civilization in this publication, the inventors of the present invention are as follows.

(1) Graphite can be processed at high speed because the cutting resistance in machining is 1/5 to 1/10 compared to that of metal.

(2) Since graphite is a material that is easier to finish by hand than metal, it can be easily finished by hand work on the part or process that was dependent on electric discharge machining.

(3) Graphite is a material having a very small coefficient of thermal expansion, and thus it is easy to obtain the degree of plastic molding.

(4) The specific gravity of graphite die is less than 1/4 of the specific gravity of mold, and it is comparatively light, so it is easy to handle and easy to operate plastic molding die even for complicated work and high speed work.

According to the above effect, it was possible to respond to the molding of the local rod and the prototype plastic product.

However, it has been newly discovered by the present inventors that the following points should be considered in the heterogeneous graphite die for plastic molding.

That is, in the case of molding the plastic, for example, considering a thermoplastic plastic as an example, the plastic material is heated to its plasticization temperature (typically 175 to 320 ° C.) and molded in the die, and then cooled. (Typically 10 ° C) to solidify. Therefore, the graphite die for plastic molding must also have the characteristics of a rigid body capable of sufficiently enduring the pressure applied to the cavity and the characteristics of an efficient heat exchanger for cooling the heated plastic material.

In plastic molding, a viscous molten resin is injected into the die, and various kinds of colorants such as pigments, stabilizers, and other additives are added to the plastic material to enrich the color of the product. Due to this fact, the releasability between the graphite material surface of the graphite die for plastic molding and the colorant, stabilizer, and other additives such as viscous molten resin and pigment becomes a problem, and the product is difficult to remove from the die. Moreover, even if it mold-released, there existed a problem that the soot generate | occur | produced on the surface of a product.

As described above, graphite is easy to process, such as cutting, while having low surface strength and inferior abrasion resistance, so that it is also necessary to coat the surface appropriately.

In the case of forming plastic products, for example, injection molding made of thermoplastic plastic is considered as an example, but in the case of vinyl chloride resin, the molding pressure is about 141 kg / cm ² , but in acrylic resin is about 700 kg / cm ² . Molding pressure must be applied, and as a molding die, it must be capable of withstanding such molding pressure. In addition, not only the molding pressure is applied to the molding die, but also, for example, in the die in which the movable die is moved relative to the fixed die to form a sealed molding cavity, a pressure higher than the molding pressure is used to form the sealed cavity. The pressing die must be pressurized to the fixed die side. The die must also be able to withstand this pressing pressure. In the case where the die is formed of graphite, the strength against the pressure applied is not the mold strength. For this reason, it is necessary to reinforce a seedling.

In addition, the hard but soft graphite die may be flawed when the force is applied locally even in the manufacturing process and at the time of use. If this flaw occurs on the molding surface or the like, it cannot play its role as a die, so replacement must be performed without delay. However, if this defect can be reliably and simply repaired, the need for replacement is eliminated and the product price can be reduced.

The present invention has been made in view of the above circumstances, and the die itself is easy to manufacture, which is suitable for high-speed processing, and excellent releasability resistance makes the finished surface of the molded product smooth, more lightweight and convenient to handle. It is an object of the present invention to provide a die for molding plastics, which can also facilitate reinforcement and repair.

That is, in one aspect, the present invention provides a molding die in which part or all of the die is made of graphite material, preferably the graphite material is substantially isotropic graphite, and more preferably, the compressive strength of the graphite material is 800. kg / cm²Ideal, Shore hardness (H_S) Is 40 to 90, and the forming die has a volume of 0.02 cc / g to 0.25 cc / g of the micro-machining having a radius of 75 kPa to 75000 kPa measured by the mercury porosimetry of the graphite material.

In another aspect, the present invention is to provide a graphite for plastic molding in which the thermal conductivity of the graphite substrate is in the range of 30 to 300 Kcal / m.hr. ° C.

In another aspect, the present invention is a graphite die for plastic molding in which part or all of the die is made of a graphite material, and the area strength and the C _IS band of the O _IS band in the X-ray electron spectroscopy method of the graphite material. It is to provide a graphite die for plastic molding, in which the value of the strength ratio O _IS / C _IS of the area strength of the polymer is 0.05 to 0.1.

In another aspect, the present invention provides a plastic molding die in which part or all of the die is made of graphite material and a film of pyrolytic carbon is formed on part or all of the surface thereof.

In another aspect, the present invention is to provide a graphite die for plastic molding in which a coating film made of metal is molded in a range of 5 to 80 µm on at least a portion of the graphite material exposed to the molding cavity.

In another aspect, the present invention provides Al ₂ O ₃ , SiO ₂ , ZrO ₂ , SiC, TiC, TaC, B ₄ C, Cr ₂ C ₂ , Si ₃ to at least a portion of the graphite material exposed to the molding cavity. Plastic formed by forming a coating film made of ceramics containing at least one selected from N ₄ , BN, TiN, AlN, TiB ₂ , ZrB ₂ cordierite, mullite, TiO ₂ or a compound thereof in the range of 5 to 2000 μm. It is to provide a graphite die for molding.

In another aspect, the present invention is to provide a graphite die for plastic molding in which a metal reinforcing support is integrated on a part or all of the die surface other than the molding cavity surface of the graphite material to protect a substrate made of graphite.

In another aspect, the present invention also provides a repairing method for a molding die made of graphite and a repaired die.

That is, this invention makes the summary a molding die which one part or all part consists of graphite material.

In the molding die of the present invention, both graphite materials of anisotropic graphite can be used, but it is preferable to use isotropic graphite in which the characteristics such as mechanical properties and thermal properties are almost constant in any direction. This is because efficient material selection is possible and the design of the die's heat cooling and rigidity is simplified. This isotropic graphite can be obtained by using a hydrostatic pressure pressurized rubber press machine, which is denser than anisotropic graphite and has a very high strength.

In general, the hardness of the graphite material is larger, but it is preferable, but the Shore hardness (H _S ) is in the range of 45 to 90 in order to be able to process at a higher speed and to be able to completely release the mold from various plastics and ceramics. desirable.

In addition, the compressive strength is preferably 800 kg / cm 2 or more in order to sufficiently withstand the pressure during injection molding. This can be obtained by adjusting the mixing of the raw material powder and the binder of the graphite material or adjusting the firing temperature.

Although the bulk density of the graphite material is generally 1.40 to 1.95, the volume density of the graphite material is preferably 1.70 or more in terms of fine pore distribution and hardness of the graphite material.

In the metal forming dies used in the related art, micromachining is not present in the plastic dies of the moldings, and thus, it is not possible to sufficiently degas the additives volatilized by heating. By utilizing micropores, it is possible to make a molding die capable of sufficiently removing gas. The preferred porosity of the graphite material is about 0.02 cc / g to 0.25 cc / g, which occupies the micropores having a radius of 75 GPa to 75000 GPa measured by mercury porosimetry by using a mercury porosimeter.

The present invention also provides a graphite die for plastic molding which can efficiently cool a plastic material after molding and can improve the efficiency of the molding die. Therefore, the graphite material constituting the graphite die for plastic molding is therefore required. It is preferable to make the lower limit of the thermal conductivity of a base material 30Kcal / m.hr.degree.

If the thermal conductivity is smaller than this, cooling of the molded article in the cavity of the graphite die for plastic molding cannot be made favorable. The upper limit of the thermal conductivity of the graphite die for plastic molding is preferably 300 Kcal / m.hr. ° C. This is because if the thermal conductivity is larger than this, the plastic material is solidified before die molding in the cavity of the plastic material is completed.

As described above, in order to make the thermal conductivity of the graphite die for plastic molding to be in the range of 30 to 300 Kcal / m.hr. ° C, it is necessary to make the graphite constituting the base material of the graphite die for plastic molding into a constant dense body. As shown in the examples of the present invention, there is a method in which a graphite material is charged into a die and molded, and then fired at 1000 ° C. for 100 hours and then graphitized at 3000 ° C. to obtain a graphite material. As another method, a method obtained by impregnating stripping pitch or resin into the pores of a porous graphite material and pulverizing it, or plastic molding having a thermal conductivity within the above range by incorporating graphite and the like by impregnating a metal such as copper or tin. There is a method of using a graphite die for.

Another object of the present invention is to provide a graphite die for plastic molding which can improve the releasability between the surface of the graphite material and the molten resin or colorant, stabilizer, and other additives, and prevent the occurrence of burning on the surface of the product.

That is, one of the graphite dies for plastic molding according to the present invention is based on the chemical properties of the graphite material, and the area strength of the O _IS band and the area strength of the C _IS band in the X-ray electron spectroscopy (ESCA) of the graphite material. The value of the intensity ratio O _IS / C _IS is 0.05 to 0.1.

X-ray electron spectroscopy is a method of detecting the photoelectron generated by irradiating soft X-ray (Alkα1.2 1487eV) on the sample surface under high vacuum (10 ^-8 mmHg) by energy splitting with an analyzer.

The value of the strength ratio O _IS / C _IS is a measure of the degree of formation of oxygen-containing functional groups on the surface of the graphite treated surface. Graphite materials having a strength ratio O _IS / C _IS greater than 0.1 have oxygen atoms on the surface. Many functional groups are distributed in a very high ratio.

Therefore, the graphite material having a value of strength ratio O _IS / C _IS greater than 0.1 is very wet with molten resin and other additives, which causes deterioration of the releasability thereof and generation of the surface of the product.

On the other hand, when the value of the intensity ratio O _IS / C _IS is 0.05 to 0.1, the releasability with the molten resin, other additives, etc. is good, and the burning of the product surface hardly occurs.

In addition, the value of the strength ratio O _IS / C _IS smaller than 0.05 has little change in effect even though the price is high to produce the graphite material in the state.

The graphite die for plastic molding composed of such a graphite material improves releasability with colorants, stabilizers, other additives, and molten resins in which oxygen atoms of oxygen-containing functional groups are incorporated into the plastic material.

The present invention also provides a die having various coatings on the cavity surface as a means for improving the releasability and surface strength of the graphite die.

Graphite is somewhat porous and can sufficiently exhibit the anchoring effect of the coating film by using an open hole on its surface. However, when the coating film is formed on the graphite surface, if the thickness is too thick, the coating film is easily peeled off due to the thermal expansion difference between the graphite and the coating film. On the contrary, when the coating film is too thin, the release effect becomes small and the coating meaning is lost.

In general, when forming a coating film on the surface of an object, one thing to be careful about is that the difference in thermal expansion rate between the coating film and the material side on which it is formed should be small. In particular, in the case of frequently used in a heat cycle of a constant width, such as a die for plastic molding as the object of the present invention, if there is a difference in thermal expansion between the substrate and the coating, the durability of the coating is likely to be impaired.

And, while satisfying such conditions, the molded coating layer is chemically or physically affected by chemical or physical impacts such as various kinds of additives and reinforcing materials added to the plastic material and its reinforcement, and by cleaning agents and impacts when die washing. It must be sufficient to protect the die against impact.

As a coating for the purpose as described above, the inventors have found that pyrolytic carbon coating, metal coating and ceramic coating are excellent.

In the present invention, in order to increase the adhesion between the graphite material and various coatings, an appropriate amount of pores is required in the graphite material, and the volume occupied by the micropores having a radius of 75 kPa to 75000 kPa measured by mercury intrusion is 0.2 cc / g. It is best to use a graphite material which is from 0.25 cc / g.

The pyrolytic carbon film can be formed by CVD (Chemical Vapor Deposition) method. In the CVD method, a pyrolytic carbon film is formed by reacting hydrocarbon gas, such as methane and propane, on the surface of a high temperature graphite material in the presence of a carrier gas. The processing temperature in this case is 1000 to 2500 degreeC, Preferably it is the range of 1100 degreeC-2000 degreeC. As a carrier gas, hydrogen is optimal. Moreover, it is preferable to perform reaction under normal pressure or reduced pressure, and under pressure in view of the uniformity and flatness of a film.

The thickness of the thermally decomposed carbon film formed in this way is preferably 0.5 µm or more, and preferably in the range of 0.5 to 500 µm. In addition, the film can be controlled by the concentration of the hydrocarbon gas, the treatment temperature, and the treatment time. In order to ensure the stability of the die, the surface layer of the graphite material is made of pyrolytic carbon so that the thermal expansion difference force is not applied between the graphite material and the pyrolytic carbon layer or that the thermally decomposed carbon layer is slightly compressed during cooling. The thermal expansion coefficient of the material is in the range of 450 ° C. at room temperature, preferably 1.7 × 10 ⁻⁶ .C ⁻¹ or more, and preferably in the range of 1.7 × 10 ⁻⁶ .C ⁻¹ .

The film of pyrolytic carbon is hard to get wet with plastics, and release property can be maintained even without coating with a release agent or plating. It also has excellent wear resistance. In addition, the thermally decomposed carbon film has a compact structure, so that the finished surface of the molded article can be smoothly finished.

The present invention also provides a graphite die for plastic molding, wherein the base material is made of graphite material and the metal side is coated on the cavity side.

As the method for forming the coating film, so-called vacuum deposition, vapor deposition, sputtering methods such as CVD and PVD, thermal spraying and the like can be appropriately employed. For example, in the vapor phase plating method, gaseous metals such as metal halides are transported to a large high-temperature chamber accommodating an object to be processed, and uniformly disperse the metal gas in the same chamber, and the graphite material can withstand high temperatures at this time. This vapor plating method is suitable for forming a coating film on graphite material. In the case of a die having a relatively smooth cavity surface, it is easy to form a coating film by a vacuum deposition method.

Moreover, as another method of forming a metal coating film, you may carry out by what is called a pack method, such as a colorizing and a chromizing. In this pack method, a metal permeation layer is formed in a required part of the graphite material by embedding a graphite material in a semi-closed container filled with a powder penetrant containing a metal such as chromium. This pack method is advantageous in forming a metal coating film because it is not necessary to form a vacuum state and the object to be processed can be stored by a penetrant.

As the metal forming the coating film, one selected from chromium titanium, aluminum, or a compound thereof is preferably used. This is because it is necessary to improve the releasability of the finished graphite die for plastic molding and to have sufficient resistance to its physical or chemical impact.

Here, the thickness of the coating film formed on the surface of the graphite material exposed on the molding cavity side of the graphite die for plastic molding is preferably in the range of 5 µm to 80 µm. When a coating film thicker than this range is formed, a crack may arise in a coating film, or this coating film itself may peel from a graphite surface. In addition, if the thickness of the coating film is less than 5㎛ because it is difficult to release the plastic product.

In addition, when the coating film is formed of a metal, the coating film is formed from the plastic material side, which protects the graphite material from chemical shocks caused by active gases and the like, and also protects the graphite material from mechanical shocks when forming and washing frequently. There is a number.

The present invention also provides a graphite die for plastic molding in which a base material of a die used for plastic molding is formed of graphite material and the cavity surface is coated with ceramic.

Ceramic materials include Al ₂ O ₃ , SiO ₂ , ZrO ₂ , SiC, TiC, TaC, B ₄ C, Cr ₂ C ₂ , Si ₃ N ₄ , BN, TiN, AlN, in terms of releasability and physical and chemical resistance. When selected from TiB ₂ , ZrB ₂ cordierite, mullite, TiO _2, or a compound thereof, it is preferable to form a ceramic coating film in a range of 5 to 2000 μm from a ceramic containing at least one kind. When a coating film thicker than this range is formed, a crack may arise in a coating film, or a coating film itself may peel from a graphite surface. In addition, if the thickness of the coating film is thinner than 5㎛ because it is difficult to release the plastic products.

As a method of forming this coating film, methods such as carbide conversion, sputtering such as CVD and PVD, thermal spraying, and sol-gel can be adopted. For example, in order to coat the surface of the graphite material with silicon carbide by the CVD method, the graphite material can be reacted on the surface of the graphite material in the following manner to preserve the shape of the graphite material.

CH ₃ SiCl ₃ → SiC + 3HCl

For example, the method of applying pack cementation may prepare a graphite material processed into an arbitrary shape, embed it with a mixture of silicon carbide powder and silicon dioxide powder in a heat-resistant container, preferably a graphite material container, The heat treatment in the temperature range of 2300 ° C. can convert silicon carbide to the graphite surface.

The various coating films described above protect the graphite material from chemical shocks caused by the active gas generated from the plastic material side, and also protect the graphite material from mechanical shock in the case of frequent molding and cleaning, and also improve the releasability. It is.

In addition, in the case where the various coatings are partially applied to the graphite material, it is possible to sufficiently remove the gas generated during plastic molding by utilizing the micropores of the graphite material, thereby preventing the occurrence of pinholes or the like in the molded product. have.

The present invention also provides a molding die in which a metal reinforcing member is integrated on a part or all of the die surfaces other than the molding cavity surface of the graphite material to protect the substrate made of graphite.

As a part which forms a reinforcement member, it is necessary to be at least one part or all die surface other than a molding cavity surface. The type of die that presses the movable die against the fixed die is a direction in which the pressing force is applied to reinforce the outside of the forming cavity.

In addition, in the graphite die for plastic molding, for example, as shown in FIG. 3, the graphite substrate located on the opposite side of the molding cavity is protected by the reinforcing member, but is external to the graphite die for plastic molding 20. When a force is applied from the force, the force is dispersed throughout the plastic die 20 for plastic molding with the reinforcing member 25 interposed therebetween. In other words, the reinforcing member 25 disperses the applied force while ensuring the strength of the graphite substrate constituting the graphite die 20 for plastic molding. Therefore, the graphite substrate is not damaged by the force applied from the outside.

In addition, although the molding pressure is applied to the molding cavity 23 by the injected ceramic material, this pressure is directly applied to the graphite substrate, but the graphite substrate is backed up by the reinforcing member 25, and thus the molding pressure is also applied. There is no crack or breakage.

The present invention also provides a repaired plastic molded carbon die which can be sufficiently reused using a carbonaceous material as it is, constituting the die.

That is, as one method, for example, as shown in FIG. 4, it is necessary to first insert the water-retaining material 26 made of a carbon-based material into the water-repairing place where the flaw of the carbon-based material has occurred. In this case, the "insertion" refers to the insertion of the carbon-based material constituting the die so that there is no gap, and the "insertion" of the water-retaining material 26 is performed as is or by screwing or bolting. It is fixed on the carbon-based material side.

Of course, this water retaining material 26 is made to face the plastic die carbon die 20 by cutting and polishing.

That is, it shape | molds according to the shape of this plastic shaping | molding carbon die 20, and it prevents the plastic shaping | molding by the plastic shaping carbon die 20 after repairing.

As another repair method, for example, as shown in FIG. 5, an adhesive 27 comprising a thermosetting resin or an aggregate of carbon-based aggregate is attached and attached to a place to be repaired of the carbon die 20 for plastic molding. After the solidification or the carbonization, the shaping is performed in accordance with the shape of the carbon die 20 for plastic molding.

In this case, first, it is necessary to attach and attach the adhesive 27 to the repair point where the flaw of the carbonaceous material is generated as shown in FIG. The adhesive 27 contains thermosetting resins such as phenol resins, urea resins, melamine resins, xylene resins, unsaturated polyester alkyd resins, epoxy resins, polyimide resins, franc resins and aniline resins. This is because it is easy to heat together with a carbon-based material excellent in heat resistance and becomes a dense body by heating, and is also easily carbonized by firing. In order to form the adhesive 27, carbonized aggregate such as carbon, wood chips, plant fibers, or the like may be mixed into the above-mentioned thermosetting resin. In this case, it is preferable to carbonize this adhesive 27 completely by baking. Of course, the graphite-based material does not change due to the firing in this case.

If the point to be repaired is relatively small as shown in Fig. 5, it is preferable to attach the adhesive 27 to the place and solidify or carbonize as described above. In the case where the part to be repaired is not a molding surface or a die for molding plastic at a relatively low molding pressure, the adhesive 27 is only heated and solidified together with the carbon-based material on the die side. You may also However, as long as this repair part requires a comparative degree, it is more suitable to carbonize by baking the adhesive 27, and to make it homogeneous with a carbon-type material.

As a matter of course, the adhesive 27 is cut and polished so as to be fitted to the carbon die for plastic molding. That is, it shape | molds according to the shape of this plastic shaping | molding carbon die 20, and it prevents the plastic shaping | molding by the plastic shaping | molding carbon die 20 after repair.

Again, as another repair method, for example, as shown in FIG. 6, a repair material 26 made of graphite material is attached to the place to be repaired of the carbon die 20 for plastic molding with the adhesive 27. There is a method of shaping according to the shape of the graphite die 20 for plastic molding.

When the location to be repaired is relatively large as shown in FIG. 6, it is easier to attach the repair material 26 in this way, and the amount of the adhesive 27 to be used can be saved, which is advantageous.

As described above, the water-retaining material 26 and the solidified or carbonized adhesive 27 are cut to form a surface fitted to the graphite die 20 for plastic molding. In this case, processing such as cutting of the adhesive 27 and the water retaining material 26 is extremely easy compared with the so-called mold repair because they have relatively low cutting resistance.

Hereinafter, the present invention will be described in detail with reference to the following Examples.

Example 1

The mixture obtained by heating and mixing the blend consisting of coke and coal tar pitch is pulverized, and then molded by pulverizing press under hydrostatic pressure. An isotropic graphite material having a / g volume density of 1.82 was obtained.

Using this graphite material, the stationary die 21 and the movable die 22 of the injection die molding die shown in FIG. 1 were manufactured.

The processing time for the production of this molding die was shortened to about 1/5 of that of the metal molding die.

In addition, the polyvinyl chloride resin was used for the molded article material at a molding temperature of 170 ° C using the obtained injection molding die, and continuous molding was performed for 250 hours. As a result, deposits and mold release defects on the molding die did not occur.

Example 2

The molding die for spherical molding was produced using the graphite material obtained by the method similar to Example 1. The processing time required for fabricating the molding die was shortened to about 1/8 of that of the metal forming die.

Using the obtained molding die for injection molding, a mixture of the fine silicon nitride powder and the additive was molded to continuously form a spherical molded article for bearing. As a result, no cavities, honeycomings, recesses, grooves and rim-shaped ripples did not occur, release defects were prevented, and no deposits were found.

Example 3

In the same manner as in Example 1, the graphitization conditions were slightly changed, and the thermal expansion coefficient from room temperature to 450 ° C. was 6.0 × 10 ⁻⁶ C ⁻¹ , and the micropore volume 0.05cc / g volume density 1.95 thermal conductivity with a radius of 75 kPa to 75000 kPa was obtained. Substrate consisting of an isotropic graphite material at 140 Kcal / m.hr. ° C and a thermal expansion coefficient of 5.0 × 10 ⁻⁶ C ⁻¹ from room temperature to 1000 ° C., micropore volume of 0.09 cc / g volume density of 75Å to 75000Å An isotropic graphite material having a thermal conductivity of 70 Kcal / m.hr. ° C was obtained.

Using this isotropic graphite material, a fixed die movable die, a guide pin, and the like for forming the molding die were molded as shown in FIG. The processing time required for this molding was reduced to about 1/8 compared with metal molding.

Using the obtained graphite die 20 for plastic molding, the time required for recycling of heating and cooling was 20 seconds for the production of a plastic product made of polyamide resin and continuously molded for 50 hours. As a result, problems such as deposits on the metal and mold release defects did not occur.

Example 4

The die for injection molding was produced using the graphite material whose strength ratio O _IS / C _IS of ESCA is 0.05.

Using this die, the time required for heating and cooling recycling of the production of the plastic product by the polyamide resin was 20 seconds, and continuous molding was performed for 50 hours. As a result, mold release with the molding die could easily be performed as a product, and problems such as sooting and so on on the surface of the product could not be found.

Example 5-1

The molding die for injection molding was produced using the graphite material whose strength ratio O _IS / C _IS of ESCA is 0.1.

The obtained injection molding die was used to continuously mold 250 hours using polyvinyl chloride resin at the molding material at a molding temperature of 170 ° C. As a result, no release defect occurred.

Example 5-2

The die for injection molding was produced using the graphite material whose strength ratio O _IS / C _IS of ESCA is 0.2.

Using this die, continuous molding was attempted, with the time required for the production of a plastic product made of polyamide resin and recycling between heating and cooling being 20 seconds. As a result, after 20 hours of use, soot was formed on the surface of the product and the mold release was not smoothed.

Example 6

The mixture obtained by heat-mixing the blend consisting of coke and coal tar pitch is pulverized and then calcined by a laver press, and the thermal expansion coefficient (1000 ° C. at room temperature) is 2.0 × 10 ^-6 C ^-1 , Shore hardness is 52, 75Å to An isotropic graphite material having a micropore volume of 0.08 cc / g of 0.08 cc / g volume density of 1.82 was obtained. Using this isotropic graphite material, it was processed into shapes of compression dies and dies.

This was placed in a furnace and heated to 1300 ° C., hydrogen gas was used as a carrier gas, and fed into a methanol furnace under reduced pressure to form a thermally decomposed carbon film having a thickness of 10 μm on the surface of Sangdai and Dai. Thus, as shown in FIG. 2, a die (1) die (2) for compression molding in which a pyrolytic carbon film was formed on the surface of the graphite material was obtained. The processing time required for such die fabrication was reduced to about one third as compared to the metal die fabrication.

Using the obtained die for compression molding, 1000 molded articles made of vinyl chloride resin were continuously molded. As a result, problems such as deposits on the die and mold release defects did not occur.

Example 7

The mixture obtained by heat-mixing the blend consisting of coke and coal tar pitch is pulverized, then molded into a Raver press, calcined and graphitized, and has a thermal expansion coefficient of 500 × 10 ^-6 C ^{-1 from} 75 to 75000 kPa at room temperature to 450 ° C. An isotropic graphite material having a common 0.07 cc / g volume density of 1.85 thermal conductivity of 80 Kcal / m.hr. ° C was obtained.

Using this isotropic graphite material, a fixed die, a movable die, a guide pin, and the like for forming the molding die as shown in FIG. 1 were molded. The processing time required for this molding was reduced to about 1/8 of that of metal molding.

And the part which wants to form the coating film which consists of metal on the part exposed to the shaping cavity 23 at least of the graphite die material shape | molded in this way is coat | covered with vegetable fiber which is easy to carbonize, such as cotton cloth and abrasion. Thus, the graphite material is placed in a semi-closed container packed with a potassium chloride penetrating agent and a Cr powder 55 parts Al ₂ O ₃ 45 parts accelerator. In this case, vibration is imparted to the sealed container so that the penetrant is densely packed in the fiber bundle.

The above is to infiltrate by heating to about 800 to 1100 ℃, in the initial heating of about 300 ℃ is to carbonize to play a role as a filter. Thus, when heated to 800 to 1100 ° C., halides and metals added as accelerators in the penetrant react with metals to produce metal halide vapors. The metal halide vapors pass through the filter described above to reach the surface of the graphite material. Metals precipitated on the surface of the material and some penetrated to form a coating film. Moreover, this thickness was 30 micrometers in chromium.

Using the obtained graphite die 20 for plastic molding, the time required for recycling of heating and cooling was 20 seconds for the production of a plastic product made of a polyamide resin, and continuous molding was performed for 50 hours. As a result, problems such as deposits on the metal and mold release defects did not occur.

Example 8

The die is made of an isotropic graphite material with an expansion coefficient of 5.0 × 10 ^-6 C ^-1 from room temperature to 450 ° C, a micropore volume of 0.07 cc / g with a radius of 75 kPa to 75000 kPa, and a thermal conductivity of 80 Kcal / m.hr. The SiC film was coat | covered by the thermal CVD method on the molded object surface obtained by shape | molding. The coating method was a method in which a molded body of graphite was placed in a reaction vessel, heated at 1500 ° C., reacted for about 5 hours while introducing a mixed gas of CH ₃ SiCl ₃ and hydrogen to form a SiC layer having a thickness of about 100 μm.

Example 9

The BN film was coat | covered by the thermal CVD method on the molded object surface obtained as another coating method. The coating method was a method in which a shaped body of graphite was placed in a reaction vessel, heated to 1200 ° C., and reacted for about 7 hours while introducing a mixed gas of BCl ₃ , NH _3, and hydrogen to form a BN layer having a thickness of about 75 μm.

Example 10

Alumina was thermally sprayed on the surface of the graphite material using a common spraying method to form an alumina layer having a thickness of about 500 µm, which was used as a coating film.

Using the obtained graphite die 20 for plastic molding, the time required for recycling of heating and cooling was 20 seconds for the production of plastic products made of polyamide resin, and continuous molding was performed for 50 hours. As a result, problems such as deposits on the metal and mold release defects did not occur.

Example 11

As shown in FIG. 3, the reinforcing member 25 made of metal was integrally formed on the die surface other than the surface of the molding cavity 23 of the graphite substrate at least. The die shown in FIG. 3 is a two-division type of the graphite die 20 for plastic molding with a fixed die, and the surface of the reinforcing member 25 fixed to each die side is formed on the parting surface between the fixed die and the movable die. It is formed to match. As a result, when the fixed die and the movable die are pressurized by a strong pressure, the protection between the fixed die and the movable die made of these graphite materials is secured.

Example 12

The repair part where the flaw etc. of the graphite material generate | occur | produced was cut into predetermined shape, and it was set as the formation which is easy to insert the repair material 26. FIG. Thereafter, a water retaining material 26 made of a carbon-based material was forcibly inserted into this portion such that there is no gap as shown in FIG. 4, and the water retaining material 26 was fixed to the graphite material side forming the die.

Example 13

As another repair method, a method as shown in FIG. 5 was used. First, as the adhesive 27, a phenol resin was used as the substrate and graphite powder was added thereto. This adhesive 27 was affixed to a repair point using a spatula etc. This adhesive 27 was charged together with a graphite material in a furnace and fired at a temperature of 1000 ° C. for about 10 hours in a non-oxidizing atmosphere. As a result, the adhesive 27 at the repair point was completely carbonized and completely integrated with the graphite material constituting the die. Thereafter, the solidified adhesive portion was molded in accordance with the shape of the graphite die for molding plastics 20.

First, as the adhesive 27, a phenol resin was used as the substrate and graphite powder was added thereto. This adhesive 27 is attached to a repair point using a spatula, etc., and the repair material 26 which consists of a graphite material of the same quality as the graphite die 20 for plastic molding is attached to this adhesive 27 as shown in FIG. Likewise, it is impregnated to the outside.

Thereafter, the adhesive 27 and the water retaining material 26 were charged together with the graphite material constituting the die into the furnace and fired at a temperature of 1000 ° C. for about 10 hours in a non-oxidizing atmosphere. For this reason, the adhesive 27 in the repair part was completely carbonized, and was fully integrated with the graphite material which comprises the repair material 20 and the die | dye.

Thereafter, the adhesive 27 or the water retaining material 26 in each of the above examples was cut by a grinder or the like to match the predetermined surface of the graphite die 20 for plastic molding. That was to emboss.

Plastic molding was performed using the graphite die 20 for plastic molding according to each repaired embodiment. However, no trace of repair was transferred to the surface of the plastic product, and carbonized adhesive was used even after repeated use. ) And the water retaining material 26 did not peel off.

Claims (15)

A molding die in which part or all of a die used for molding plastic or ceramic is formed of graphite material, wherein the graphite material is substantially isotropic graphite, and its compressive strength is 800 kg / cm 2 or more, and the shore hardness ( H _S ) is 40 to 90, the molding die, characterized in that the volume occupied by the micropores having a radius of 75 ~ 7500 Å measured by the mercury intrusion method of the graphite material is 0.02cc / g to 0.25cc / g. The molding die according to claim 1, wherein the thermal conductivity of the graphite material is in the range of 30 to 300 Kcal / m.hr. 2. The molding according to claim 1, wherein the strength ratio O _IS / C _IS of the area intensity of the O _IS band and the area intensity of the C _IS band in the X-ray photoelectron spectroscopy of the graphite material is 0.05 to 0.1. Yongdai. The molding die according to claim 1, wherein a film of pyrolytic carbon is formed on part or all of the cavity surface of the molding die. The molding die according to claim 4, wherein a film of pyrolytic carbon is formed by a CVD method. The molding die according to claim 4, wherein the pyrolytic carbon film is formed in a range of 0.5 to 500 mu m. The molding die according to claim 1, wherein a coating film made of metal is formed on part or all of the cavity surface of the molding die. 8. The molding die according to claim 7, wherein the coating made of metal is formed by pack cementation coating. 8. The molding die according to claim 7, wherein the metal coating film is in the range of 5 to 800 mu m. The method of claim 1, wherein a portion or all of the cavity surface of the forming die is Al ₂ O ₃ , SiO ₂ , ZrO ₂ , SiC, TiC, TaC, B ₄ C, Cr ₂ C ₂ , Si ₃ N ₄ , BN And a coating film formed of a ceramic containing at least one selected from TiN, AlN, TiB ₂ , ZrB ₂ , cordierite, mullite, TiO ₂ or a compound thereof. The molding die according to claim 10, wherein the coating made of ceramic is formed in a range of 5 to 2000 mu m. 12. The molding die according to any one of claims 1 to 11, wherein a reinforcing member is integrated on a part or all of the surfaces other than the cavity surface of the molding die to protect the molding die. The molding die according to claim 1, wherein a repair material made of a carbon-based material inserted into a portion to be repaired of the molding die is repaired according to the shape of the molding die. 2. The adhesive according to claim 1, wherein the thermosetting resin, which is solidified or carbonized in addition to the portion to be repaired in the molding die, or an adhesive comprising carbon-based aggregate mixed therein is repaired according to the shape of the molding polycarbon die. Molding die. 2. The molding carbon according to claim 1, wherein the repairing material made of graphite material is added to the portion to be repaired by the molding die through a thermosetting resin or an adhesive comprising carbon-based aggregate mixed therein, and then solidified or carbonized. A molding die, which is repaired according to the die shape.

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