JP2009226459A - Mold release agent for die casting, method for imparting mold releasability to mold for die casting and method for casting die-cast product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold release agent for die casting which can suppress the generation of the roughening of a cast skin in a die-cast product, and to provide a mold releasing method and a casting method. <P>SOLUTION: Disclosed is a mold release agent for die casting composed of a colloidal aqueous solution obtained by dispersing the nanoparticles of a metal oxide other than silicon dioxide into water without adding a dispersant. Also disclosed is a method for imparting mold releasability to a mold for die casting characterized in that the molding face of a mold for die casting composed of a colloidal aqueous solution obtained by dispersing the nanoparticles of a metal oxide other than silicon dioxide into water without adding a dispersant, and next, the water is evaporated. Also disclosed is a method for producing a die-cast product characterized in that a molten metal is injected into the mold for die casting with the molding face coated with a colloidal aqueous solution obtained by dispersing the nanoparticles of a metal oxide other than silicon dioxide into water without the addition of a dispersant, and from which the water is evaporated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mold release agent for die casting, and more particularly to a mold release agent for die casting comprising a colloidal aqueous solution of a metal oxide other than silicon dioxide, a mold release imparting method using the colloidal aqueous solution, and a die casting product casting method.

  Die-casting refers to a technique in which molten non-ferrous metals such as aluminum, magnesium, and zinc or their alloys (hereinafter referred to as “molten metal”) are press-fitted into a precision mold at a high speed and are instantly formed. Die-casting is characterized by high dimensional accuracy, the ability to produce products with thin wall thickness and complex shapes, and mass production, and is widely used in the manufacture of automotive parts and precision machine parts. Has been.

  The die-casting machine is equipped with two molds, a fixed mold and a movable mold. When the molten metal that has been press-fitted into the cavity formed by combining the fixed mold and the movable mold is solidified, it matches the opening of the movable mold. The extrusion pin extrudes the product from the movable mold. If the mold releasability is poor, distortion and breakage of the product and breakage of the mold occur when the movable mold is opened and / or extruded.

  In order to prevent this, a mold release agent is sprayed on the molding surface of a mold every time a product is manufactured to improve mold release properties. In general, an organic release agent obtained by emulsifying a mineral oil, animal or vegetable oil, silicone oil, wax, fatty acid or the like with a surfactant is used as the release agent (for example, JP-A 63-265996). JP, 2003-275845, A).

  However, the use of an organic mold release agent has a problem that when a high-temperature molten metal is injected, the organic component of the mold release agent adhering to the mold is gasified and the casting surface can be roughened on the product.

  Japanese Patent Application Laid-Open No. 11-77234 discloses a release agent in which inorganic fine particles are added to an organic release agent. However, in the release agents whose effects are actually confirmed in the examples of this document, the inorganic fine particles are dispersed in an organic release agent (base release agent) containing a dispersant, No investigation has been made on release agents that do not contain organic components such as dispersants. Moreover, no mention is made regarding the casting surface of the cast product. Therefore, this document does not indicate a solution to the problem that the casting surface is roughened in the product due to the release agent.

JP 63-265996 A JP 2003-275845 A JP-A-11-77234

  In view of the above problems, an object of the present invention is to provide a release agent for die casting, a release method, and a casting method that can suppress the occurrence of roughness of the casting surface in a die-cast product.

According to the present invention, there is provided a mold release agent for die casting comprising a colloidal aqueous solution in which nanoparticles of metal oxide other than silicon dioxide are dispersed in water without a dispersant.
In addition, according to the present invention, there is provided a die casting product casting method characterized in that the mold release agent is applied to the molding surface of the die before pouring the molten metal into the die casting die.

  Further, according to the present invention, a colloidal aqueous solution in which nanoparticles of metal oxide other than silicon dioxide are dispersed in water without a dispersant is applied to the molding surface of a die casting mold, and then water is evaporated. A method for imparting releasability to a die casting die is provided.

  Furthermore, according to the present invention, a die casting mold having a molding surface in which nanoparticles of metal oxide other than silicon dioxide are dispersed in water without a dispersant and then water is evaporated, There is provided a method of casting a die-cast product characterized by injecting molten metal.

  In the release agent of the present invention, metal oxide nanoparticles adhere to the molding surface of the mold and impart releasability. However, the nanoparticles do not gasify even when in contact with a high-temperature molten metal. Since it does not contain gasifying organic components such as a dispersant, the casting surface is not roughened in the die-cast product, and the quality of the product can be improved and stabilized.

  Since the release agent of the present invention is in the form of a stably dispersed colloidal aqueous solution, it is easy (for example, by simple application such as spraying) to uniformly attach the metal oxide nanoparticles to the molding surface. Can do. That is, uniform mold release properties can be imparted to the mold forming surface.

  As a result, product distortion and breakage during mold opening and die casting product extrusion and mold breakage can be prevented or reduced. Therefore, the use of the release agent of the present invention makes it possible to improve and / or stabilize product quality, improve production yield, reduce production cost, and the like.

  Further, since the release agent of the present invention uses metal oxide nanoparticles as a component imparting releasability and does not contain an organic component, the safety of the work environment (for example, flammability, ignition, health by inhalation) Damage) and the load on the surrounding environment (contamination of the surrounding environment due to diffusion / scattering) is reduced.

  Furthermore, since water as a dispersion medium can simultaneously act as a mold cooling medium, it is possible to achieve simplification / efficiency of work.

(Die-casting mold release agent)
The release agent of the present invention is characterized by comprising a colloidal aqueous solution in which nanoparticles of metal oxide other than silicon dioxide are dispersed in water without the addition of a dispersant.
Hereinafter, the release agent of the present invention will be described in detail.

In the present invention, “without adding a dispersant” means that no dispersant is added to disperse the solid content in the release agent.
It is preferable that water does not substantially contain organic substances other than the dispersant. “Substantially free of organic matter” means 10 mg / L when the amount of organic matter is measured as potassium permanganate consumption, not only when it contains no organic matter but also when it contains organic matter. The case of less than this is also included.

  As water, tap water or industrial water may be used as it is, but it is preferable to use it after removing inorganic salts by treatment with an ion exchange resin or the like. By removing inorganic salts, it is possible to prevent undesirable inorganic substances from depositing on the casting surface of the product.

In the present invention, “nanoparticles” are particles having an average primary particle diameter of 1 to 500 nm. Such nanoparticles can be dispersed in water and easily (inexpensive) without the addition of a dispersant. Preferably, the average primary particle size is 10 to 250 nm. In this range, the nanoparticles can be stably dispersed in water for a longer period.
In the present invention, the “average primary particle size” is determined from observation with an electron microscope such as TEM or centrifugal sedimentation.

  In the release agent of the present invention, the nanoparticles may be dispersed as primary particles, or may be dispersed as an aggregate of two or more particles.

  As the metal oxide other than silicon dioxide in the release agent of the present invention, a metal oxide that is insoluble or hardly soluble in water (solubility of less than 1% by weight at 100 ° C.) can be used. Examples of such metal oxides include aluminum oxide, titanium oxide, vanadium oxide, chromium oxide, iron oxide, cobalt oxide, copper oxide, zinc oxide, yttrium oxide, zirconium oxide, tin oxide, molybdenum oxide, cerium oxide, Examples thereof include tungsten oxide. Preferably, the metal oxide other than silicon dioxide is selected from the group consisting of titanium oxide, zirconium oxide and aluminum oxide.

These metal oxides may be used alone or as a mixture of two or more. As a mixture, as long as one or more metal oxides other than silicon dioxide are contained, a mixture further containing silicon dioxide may be used.
When the metal oxide is a mixture in the release agent of the present invention, the main two, three or four metal oxides are selected from the group consisting of titanium oxide, silicon dioxide, zirconium oxide and aluminum oxide. Is preferred. More preferably, the main two or three metal oxides are selected from the group consisting of titanium oxide, silicon dioxide and zirconium oxide.

The metal oxide may be modified. Modification refers to, for example, coating, hydrophilization, hydrophobization, adsorption group addition, and the like.
As the metal oxide nanoparticles, for example, those produced by a vapor phase method such as PVD method or CVD method, a liquid phase method such as sol-gel method or reverse micelle method can be used.

The metal oxide nanoparticles may be included at a concentration that is stably dispersed in water.
In view of efficient adhesion of the nanoparticles to the molding surface, the metal oxide nanoparticles are included in the release agent of the present invention, for example (the metal contained when the metal oxide is used as a mixture). It is contained in a concentration of 0.01% by weight or more, preferably 0.02% by weight or more, preferably 0.1% by weight or more, more preferably 0.2% by weight or more. Higher working efficiencies can be achieved because the use of higher concentrations provides better releasability with a small amount of application.

  On the other hand, the upper limit of the concentration of the metal oxide nanoparticles in the release agent of the present invention is not limited, but is preferably 35% by weight which is easily dispersed stably in water.

  It is preferable that the release agent of the present invention does not contain a surfactant. By not containing the surfactant, the load on the surrounding environment due to diffusion / scattering is further reduced and / or the work environment is prevented from deteriorating (for example, floor surface or tool slipping).

  The release agent of the present invention contains metal oxide nanoparticles at a concentration of, for example, 0.01% by weight or more, and preferably the balance (˜99.99% by weight) is water. When the release agent of the present invention consists of metal oxide nanoparticles and the balance of water, in addition to the aforementioned advantages, it is advantageous in terms of ease of preparation and / or handling and cost.

  The mold release agent of the present invention comprises 0.01 to 0.5% by weight (preferably 0.05 to 0.2% by weight) of metal oxide nano-particles when used (when applied to a die casting die). Prepared to contain particles.

  Although the material of the metal mold | die in which the mold release agent of this invention is used is not specifically limited, For example, it may be iron or an iron alloy. Further, the metal (molten metal) to be released is not particularly limited, and may be, for example, a non-ferrous metal such as aluminum, magnesium, zinc, or an alloy thereof.

(Method for imparting releasability)
The method for imparting releasability to a die casting die according to the present invention is characterized in that a metal oxide colloid aqueous solution in which metal oxide nanoparticles other than silicon dioxide are dispersed in water without addition of a dispersant is formed on the molding surface of the die. And then evaporating the water.

  In the release property imparting method of the present invention, the metal oxide colloid aqueous solution is a metal oxide colloid aqueous solution as described above as the mold release agent of the present invention. Therefore, the above-mentioned release agent of the present invention can be used in the release property imparting method of the present invention.

For the application of the aqueous colloidal solution (or the above-mentioned release agent of the present invention) to the molding surface of the mold, a commonly used technique such as spraying using a spray nozzle can be used. The coating amount is not particularly limited, but is preferably an amount capable of evaporating the water constituting the aqueous colloidal solution applied to the molding surface in about several seconds to several tens of seconds after coating. After application, unevaporated water may be removed by air blowing. The coating amount can be, for example, 0.01 to 10 L / m ² depending on the concentration of the metal oxide in the aqueous colloidal solution.

  According to the mold release imparting method of the present invention, the metal oxide nanoparticles in the colloid applied to the mold forming surface adhere to the molding surface by evaporation of water constituting the aqueous colloid solution. Provides releasability. Here, the metal oxide nanoparticles do not gasify even when in contact with high-temperature molten metal, and do not contain other organic components that gasify such as dispersants, so die-cast products cast using this mold The casting surface is not roughened, and the quality can be improved and / or stabilized.

  Moreover, since the releasability can be imparted without using an organic component that has a large environmental load, the load on the surrounding environment is reduced and / or the working environment is improved. Furthermore, since the metal oxide nanoparticles are applied in the form of a colloidal aqueous solution (stable dispersion state), they can be uniformly attached to the mold surface, and uniform releasability is imparted.

(Die-cast product casting method)
The casting method of the die-cast product of the present invention is a molding surface in which a metal oxide colloidal solution in which nanoparticles of metal oxide other than silicon dioxide are dispersed in water without addition of a dispersant is applied, and then the water is evaporated. The molten metal is poured into a die casting mold having the above.

  In the casting method of the present invention, a metal oxide colloid aqueous solution in which nanoparticles of metal oxide other than silicon dioxide are dispersed in water without addition of a dispersant is as described above for the release agent of the present invention. A colloidal aqueous solution is used, and the aforementioned release agent of the present invention may be used. The aqueous colloidal solution can be applied as described above with respect to the method for imparting releasability of the present invention.

In the die casting method of the present invention, a die casting machine usually used in the die casting method can be used in accordance with a conventional method.
Briefly described with reference to FIG. 1, a die casting machine 1 includes a die casting mold 2 composed of a fixed mold 3 and a movable mold 4, a plunger 5 that presses molten metal into the mold at high speed, and a casting. A die casting machine having an extrusion pin 6 for extruding the formed die cast product is used. A spray nozzle 7 that is usually used for coating a mold release agent and / or a mold cooling medium can be used in a colloidal aqueous solution (release agent 8) coating apparatus.

The casting process is briefly as follows.
First, in a state where the movable mold 4 is opened (FIG. 1), the spray nozzle 7 of the spray device is inserted between the fixed mold 3 and the movable mold 4, and a colloidal aqueous solution is formed on each molding surface of the fixed mold 3 and the movable mold 4. (Or the aforementioned release agent 8 of the present invention) is sprayed. After spraying, the non-evaporated medium may be removed by blowing off with an air blow.

  In addition, the mold may be cooled to a predetermined temperature with a cooling medium before the application of the aqueous colloidal solution, but the water in the aqueous colloidal solution can also function as a mold cooling medium. And releasability can be applied at the same time, and the work can be simplified / efficient.

Next, the movable mold 4 is closed, and the molding surface of the movable mold 4 is combined with the molding surface of the fixed mold 3 to form a molding space (cavity). Subsequently, the molten metal is pressed into the cavity at high speed by the plunger 5. After the molten metal is cooled and solidified, the movable die 4 is opened and the die-cast product is extruded from the movable die 4 by the extrusion pin 6. The die-cast product can be extruded from the fixed mold 3 depending on the configuration of the die-casting machine used.
Thereafter, these steps are repeated.

  According to the casting method of the present invention, since metal oxide nanoparticles that do not gasify during casting can be used as a release-providing component, it is not necessary to use an organic release agent, and other agents such as a dispersant are used. Since it does not contain gasified organic components, it is possible to improve and / or stabilize the product quality without causing rough casting in the die-cast product. Moreover, compared with the casting method which uses the conventional organic mold release agent, the load to the surrounding environment is reduced and the working environment is improved.

  Furthermore, since a mold having a uniform releasability imparted by a colloidal aqueous solution of metal oxide nanoparticles is used, product quality can be improved and / or stabilized, production yield can be improved, and production cost can be reduced. .

  Hereinafter, the content of the present invention will be specifically described based on examples, but the present invention is not limited thereto.

  In this example, aluminum die casting was performed using an aluminum die casting machine with a molten metal extrusion pressure of 135 t under the operating conditions shown in Table 1. SKD-61 was used for the mold material, and ADC-12 was used for the aluminum alloy.

Table 2 shows the physical properties of the chemicals used for producing the release agent for die casting of the present invention. In addition, all the chemical | medical agents 1-6 are the catalyst chemical industry company make.

Example 1
The release agent for die casting of Example 1 was prepared by diluting the drug 1 with pure water desalted with an ion exchange resin so that the particle concentration was 0.22% by weight.
The release agent of Example 1 was sprayed for 1 second with a 10 ml spray nozzle on a stationary mold and a 10 ml spray nozzle on a movable mold (application amount per unit area: 0.74 L / m ² ). After excess water was blown off by air blow, a mold was formed by combining the movable mold and the fixed mold, and the molten metal was injected with a plunger and pressed into the mold. After the molten metal hardened, the movable mold was separated from the fixed mold, and then the product was extruded with an extrusion pin. At this time, the extrusion pressure required for the extrusion pin to extrude the product was measured.

After the product was extruded, the release agent of Example 1 was sprayed again, and the same operation as described above was repeated.
Since the mold temperature was low the first two times, it was thrown away at a low injection speed. Thereafter, die casting was performed 20 times at a high injection speed. The surface of the product cast by 20 times of die casting was observed to confirm the presence or absence of roughness of the casting surface, and the average extrusion pressure of 20 times was calculated.
Also in the following examples and comparative examples, the operation of die casting was performed in the same manner as described above.

(Example 2)
The release agent of Example 2 was prepared by diluting the drug 2 so that the particle concentration was 0.11% by weight.
(Example 3)
The release agent of Example 3 was prepared by diluting the drug 3 so that the particle concentration was 0.11% by weight.

Example 4
The release agent of Example 4 was prepared by diluting the drug 4 so that the particle concentration was 0.11% by weight.
(Example 5)
The release agent of Example 5 was prepared by diluting the drug 5 so that the particle concentration was 0.098% by weight.
(Example 6)
The release agent of Example 6 was prepared by diluting the drug 6 so that the particle concentration was 0.091 wt%.

(Comparative Example 1)
Only water containing no release agent was sprayed to make Comparative Example 1.
(Comparative Example 2)
The release agent of Comparative Example 2 was prepared by diluting the current drug 1 (release agent containing an organic substance; aqueous silicone emulsion system, solid content 22%) to a solid content concentration of 0.55% by weight. .

(Comparative Example 3)
The release agent of Comparative Example 3 was prepared by diluting the current agent 2 (release agent containing an organic substance; aqueous silicone emulsion system, solid content of 26%) so that the solid content concentration was 0.65% by weight. .

  Table 3 shows the presence / absence of roughness of the casting surface and the average extrusion pressure on the surface of the die-cast product cast using the release agent of Examples and Comparative Examples.

  When the release agent of Comparative Example 2, which is an organic release agent, was used, the surface of the die casting was roughened, and the release agent of Comparative Example 3, which is also an organic release agent, was die-cast. The casting surface was found to be rough on the surface of the product.

On the other hand, when the release agents of Examples 1 to 6 were used, no roughening of the casting surface was observed on the surface of the die cast product.
From this, it can be understood that the quality deterioration of the product that may be caused by the use of the organic release agent is prevented by the use of the release agent of the present invention.

  With respect to the average extrusion pressure, it can be evaluated that the release agents of the examples are comparable to the release agents of the comparative examples.

It is a figure which shows the one aspect | mode of the die-casting product casting method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Die casting machine 2 ... Die casting die 3 ... Fixed die 4 ... Movable die 5 ... Plunger 6 ... Product extrusion pin 7 ... Spray nozzle 8 ... Separation Mold

Claims (7)

  A mold release agent for die casting comprising a colloidal aqueous solution in which nanoparticles of metal oxide other than silicon dioxide are dispersed in water without addition of a dispersant.   2. The mold release agent for die casting according to claim 1, wherein the metal oxide nanoparticles have an average primary particle diameter of 1 to 500 nm.   3. The mold release agent for die casting according to claim 1, wherein the metal oxide nanoparticles are contained in an amount of 0.01 wt% to 35 wt% based on the total weight of the mold release agent.   The mold release agent for die-casting according to any one of claims 1 to 3, wherein the metal oxide other than silicon dioxide is selected from titanium oxide, zirconium oxide, and aluminum oxide.   A casting method for a die-cast product, wherein the mold release agent according to any one of claims 1 to 4 is applied to a molding surface of the die before pouring the molten metal into the die casting die.   A die casting mold characterized in that a metal colloidal aqueous solution in which nanoparticles of metal oxide other than silicon dioxide are dispersed in water without adding a dispersant is applied to the molding surface of the die casting mold, and then water is evaporated. Method for imparting releasability to   Applying an aqueous colloidal solution in which nanoparticles of metal oxide other than silicon dioxide are dispersed in water without the addition of a dispersant, and then injecting the molten metal into a die casting mold having a molding surface in which water is evaporated. A die casting product casting method.

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