JPH1094851A - Water soluble parting agent for die casting and its film structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a temp. drop of a molten metal and to improve its running property by forming an air layer in a space between scale shaped particles. SOLUTION: A principal material of the water soluble parting agent consists of particles of scale shaped or flake of mica, etc., further contains spheroidal particles. The spheroidal particles 2 (silicon nitride) are interposed between the scale shaped particles 1. An air layer 3 is formed between the scale shaped particles 1. Air is enclosed between the scale shaped particles 1 so as to produce a film structure of the parting agent excellent in heat insulation. When the water soluble parting agent is applied on a die, the scale shaped particles 1 and the spheroidal particles 2 are laminated to form the air layer. A binder 4 is contained in the water soluble parting agent. By this method, a lubrication parting property at taking out a product is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-soluble release agent for die casting and a film structure thereof, and more particularly to a water-soluble release agent applied to a die surface in die casting and a film structure thereof.

[0002]

2. Description of the Related Art In die casting, a mold temperature is controlled within a range of about 150 to 300 ° C. during casting.
On the other hand, the temperature of the molten metal is about 650 in the case of aluminum.
Since the temperature is as high as about ° C., the heat of the molten metal injected into the cavity is taken by the mold, and the temperature of the molten metal decreases. When the temperature of the molten metal is lowered, the fluidity of the molten metal is deteriorated, and there is a problem that the molten metal does not reach the whole area in the cavity. Therefore, the water-soluble release agent for die casting applied to the mold cavity surface is excellent in heat insulation between the mold and the molten metal,
It must be able to ensure the heat retention of the molten metal.

Further, the molten metal filled in the cavity solidifies in the cavity and is taken out as a product. However, if the solidification shrinkage of the product or the parallelism at the time of taking out the product by the die-casting machine is poor, the product and the die are not formed. Causes metal contact and galling,
There is also a problem that part of the product remains in the mold. Therefore, the water-soluble release agent for die-casting must have lubricity and release properties at the time of product removal.

[0004] Here, the conventional water-soluble release agent containing graphite as a solid lubricant is very excellent in lubricating release property, but has a defect that it is inferior in heat insulating property. On the other hand, a water-soluble release agent containing an oxide as a solid lubricant has excellent heat insulation properties, but has a disadvantage of poor lubricity release properties.

Japanese Patent Application Laid-Open No. 57-168745 discloses a method in which mica, talc, or the like is used as a main material powder, boron nitride, carbon fluoride, or the like is used as a solid lubricant, and a binder made of a water-soluble organic substance is used. A water-soluble release agent is described. When this water-soluble release agent is applied to a mold, the main material and the solid lubricating powder form a layer, and between these layers, a gas formed by decomposing the organic binder is filled to form a film. This allows the main material powder to move relatively freely.

[0006]

However, the shapes of boron nitride and carbon fluoride are scaly, and when they are laminated, the flat surfaces tend to adhere to each other and the air layer between the layers tends to decrease, so that the film of The problem of poor heat insulation is expected. In addition, since it has a scale shape, there is a problem that a contact area is large and friction is increased, so that desired lubricating release properties cannot be expected.

Accordingly, the present invention can provide a sufficient air layer to provide heat insulation when flake-like particles are contained, and improve the lubricity by improving the slipperiness of the particles. An object of the present invention is to provide a water-soluble release agent for die casting and a film structure thereof.

[0008]

In order to achieve the above object, the present invention relates to a die-casting water-soluble release agent containing at least flaky particles 1 and spherical particles 2 which is applied to the surface of a mold when the water-soluble release agent is adjacent thereto. A water-soluble mold release agent for die casting in which the spherical particles are interposed between the flat surfaces of the flaky particles to form a laminated structure in which a space is provided between the adjacent flaky particles, and an air layer 3 is formed in the space. We offer a film structure of

The present invention further provides a scaly particle having an active ingredient having a flat surface, a spherical particle, and a binder. These are dispersed in a solution and applied to a mold, whereby the scaly particles 1 are formed on the mold surface. The water-soluble mold release agent which forms the air layer 3 by mixing the spherical particles 2 and air between the flat surfaces is provided.

Here, it is preferable that a nitride coating 5 is applied to the outer periphery of the flaky particles. Further, it is preferable that the spherical particles are previously attached to the flat surface of the flaky particles before the application to the mold. Further, the particle size of the flaky particles is preferably 5 to 30 μm.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A water-soluble mold release agent and a film structure thereof according to an embodiment of the present invention will be described with reference to FIG. The main material of the water-soluble release agent is composed of flaky or flaky particles such as mica and talc. This is because it has a scale-like flat two-dimensional shape because it is scaly, and is likely to become a layer when applied to a mold. The water-soluble release agent further contains spherical particles, and is specifically composed of spherical particles of silicon nitride, silicon dioxide, magnesium oxide and the like. The best spherical shape is a perfect circle, but any shape that is relatively close to a spherical shape may be used. The scaly particles and the spherical particles are mixed, and a water-soluble polymer compound such as MC (methylcellulose) and silicone, a dispersant, a preservative, and water are added as a binder, and a water-soluble release agent is mixed.

FIG. 1 is a cross-sectional view of a film structure in which a water-soluble release agent has been applied to the surface of a mold. FIG. 1 is a drawing based on an electron micrograph of a 10,000 × magnification of a cross section obtained by applying the water-soluble release agent to a test piece, sanding the coated surface with the test piece, and cutting the cross section. You can show the same photo if needed. As is clear from FIG. 1, spherical particles (silicon nitride) 2 are interposed between the scale-like particles (mica) 1, and an air layer 3 is formed between the scale-like particles 1. Since the spherical particles 2 are in contact with the scaly particles 1 at a point or an extremely small contact area, more air is trapped between the scaly particles 1 and the air layer 3 releases the mold with excellent heat insulating properties. It becomes the film structure of the agent. Therefore, heat transfer of the molten metal to the mold is suppressed, and the fluidity of the molten metal is improved. In FIG. 1, a dotted line 4 indicates a binder. Further, in FIG. 1, in a direction in which the test piece is shifted from each other in parallel with the release agent layer (the left-right direction in FIG. 1), the spherical particles 2 are released so that the flaky particles slide and serve as rollers. Therefore, a film structure having excellent mold releasability is obtained without occurrence of galling in the mold.

The particle size of the flaky particles is 5 to 30 μm. When the water-soluble release agent is applied to the mold, the flaky particles 1 and the spherical particles 2 are laminated to form the air layer 3 as described above.
When the particle size of the flaky particles is less than 5 μm, it is difficult for air to enter between the layers, and it is difficult to form a good air layer 3. On the other hand, if the particle size of the flaky particles 1 exceeds 30 μm, the flaky particles 1 are likely to settle in the water-soluble release agent, and the flaky particles 1
Is separated and a homogeneous and stable aqueous solution cannot be obtained.

[0014] As shown in FIG.
Preferably, a nitride coating 5 is applied to the outer periphery of the substrate.
Here, the nitride is Si ₃ N ₄ , TiN, AlN, BN or the like. The coating is applied to the entire circumference of the flaky particles. When the surface treatment is applied to the scale-like particles 1 with nitride, the flow length of the molten metal is increased, and the lubricity is improved. In addition, since the wettability with the molten metal is deteriorated by the nitride coating 5, the contact angle with the molten metal is reduced, and the contact area with the molten metal is reduced. .

The scaly particles 1 or the scaly particles 1 coated with the nitride 5 are blended in an aqueous solution separately from the spherical particles, as shown in FIGS. 3 (A) and 3 (B). Spherical particles 2 on the outer peripheral surface of flaky particles 1 or the outer peripheral surface of nitride 5
May be attached in advance. By adopting such a particle form, the spherical particles 2 always intervene between the adjacent flaky particles 1, so that the air layer 3 can be reliably provided. Examples of a method for attaching the spherical particles to the outer peripheral surface of the flaky particles 1 or the nitride 5 include a method by granulation, for example, a method of coating the spherical particles with a binder and then attaching them to the flaky particles, or a method by activated bonding. For example, there is a method in which mica is heated at a high temperature to increase the adsorptivity.

Various tests were conducted on the water-soluble release agent according to the present embodiment. First, in order to confirm the lubricity of the water-soluble release agent according to the present invention, a reciprocating friction resistance test shown in FIG. 4 was performed. Samples of the present invention 1 using mica and silicon nitride as solids, Comparative Example 1 using diatomaceous earth as solids, and Comparative Example 2 using kaolin as solids were prepared. Test piece 11 of material SS41
These samples were placed on the surface of
It was coated to a cm ^2. Then, the test piece 11 was set on the movable heater 12. Movable heater 12
Was set at 15 mm / sec, and reciprocated with a stroke of 25 mm. A steel ball 13 is applied to the coating 10 with a load of 3K.
gf. Then, the test piece 11 was heated to 200 ° C., 250 ° C., and 300 ° C. by the heater 12, respectively, and the friction coefficients of the product of the present invention and the comparative example at each temperature were measured. The test results are shown in FIG. As is clear from FIG. 5, the product of the present invention shows a lower friction coefficient at any temperature as compared with Comparative Examples 1 and 2, and the friction coefficient does not change significantly even when the mold temperature changes. I understand.

Next, the flow length of the molten metal was measured using a vortex tester shown in FIG. 6 in order to confirm the effect of applying the nitride coating 5 to the outer periphery of the scale-like particles (mica) 1. . The following water-soluble release agents were prepared as samples. Invention product 2: Mica with nitride coating 10μ (12%) Spherical particles (silicon nitride) 1.5μ (3%) Invention product 3: Mica 10μ (12%) Spherical particles (silicon nitride) 1.5μ (3 %) Comparative Example 3: Mica with nitride coating 10μ (15%) Comparative Example 4: Mica 10μ (15%) The binders used in these samples were MC (methylcellulose) and silicon.

In the spiral tester, a spiral groove 21 having a rectangular cross section (opening upper side 8 mm, bottom side 7 mm, oblique side 8 mm) is engraved on a lower mold 20 having a flat surface. Each sample was applied. Then, the upper surface of the lower mold 20 was covered with an upper mold (not shown) having a central opening.
This tester was held at 300 ° C. close to the mold temperature, and the molten aluminum heated to 730 ° C. was poured from the central opening without pressure. The poured molten metal first accumulates in the lower central portion 22 and then flows outward from the central portion 22 along the spiral groove 21. The length of the molten metal that had advanced through the spiral groove 21 when a predetermined amount of the molten metal was poured was measured as a flow length. FIG. 7 shows the measurement results.

As is clear from the test results shown in FIG. 7, the product 2 of the present invention obtained by subjecting mica as scaly particles to a surface treatment with a nitride has the longest flow length of the molten metal of 62 cm, which is excellent. It can be seen that the liquid has excellent fluidity. Also,
When Comparative Example 3 and Comparative Example 4 were compared, it was confirmed that when the nitride coating was applied to the flaky particulate particles, the flow length was increased by about 10% as compared with the case where the coating was not applied. Incidentally, it was also found that the products 2 and 3 of the present invention containing silicon nitride which is a spherical particle had an extremely long flow length as compared with Comparative Example 4 which was only mica, and the flaky particle and the spherical particle shown in FIG. The heat insulating effect of the air layer formed by laminating is supported.

Next, in order to confirm the influence of the particle size of the spherical particles on the fluidity, a similar test was conducted using a spiral tester shown in FIG. The prepared samples are as follows. Sample A: Mica 10μ (12%) + silicon nitride 20μ (3%) Sample B: Mica 10μ (12%) + silicon nitride 1.5μ (3%) Sample C: Mica 10μ (12%) + silicon nitride 6 μ (3%) The binders used in these samples were MC (methyl cellulose) and silicon. As is clear from the test results shown in FIG.
In the case of μ, the flow length did not change much, but when the particle size was 20 μ, the flow length was reduced.

The water-soluble release agent for die-casting according to the present invention and the film structure thereof are not limited to the above-described embodiments, but can be variously modified within the scope described in the claims.

[0022]

According to the water-soluble release agent for die-casting according to the first and second aspects and the film structure thereof, spherical particles are interposed between layers of the flaky particles, and air is generated between the flaky particles by the spherical particles. Since the layer is formed, the layer has excellent heat insulating properties with the mold, suppresses a decrease in the temperature of the molten metal, and improves the flowability of the molten metal. In addition, the spherical particles interposed between the flaky particles serve as rollers, and the lubricating release property at the time of removing the product is improved.

According to the water-soluble release agent for die-casting according to the third aspect, the outer periphery of the flaky particles is coated with a nitride, so that the contact angle with the molten metal is reduced and the contact area between the molten metal and the release agent is reduced. And heat transfer from the molten metal can be suppressed, so that the heat retention is excellent and the fluidity of the molten metal is improved.

According to the water-soluble release agent for die-casting of the fourth aspect, compared to the case where the flaky particles and the spherical particles are simply mixed, the two are adhered in advance before coating, so that the flaky particles are reduced. Spherical particles are always interposed between the layers, and the air layer can be reliably provided.

According to the water-soluble release agent for die-casting of the fifth aspect, the heat-insulating property can be ensured by ensuring that the air layer is formed in the coating structure by setting the particle size of the flaky particles to 5 μm or more. The separation of the flaky particles in the aqueous solution can be prevented by suppressing the increase in the sedimentation speed of the flaky particles in the aqueous solution by setting the particle diameter to 30 μm or less.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a film structure in which a water-soluble release agent according to an embodiment of the present invention has been applied to a test piece surface.

FIG. 2 is a cross-sectional view showing a scale-like particle coated with a nitride.

FIG. 3A is a cross-sectional view showing a structure in which spherical particles are preliminarily adhered to the outer peripheral surface of a flaky particle, and FIG. 3B is a sectional view in which spherical particles 2 are preliminarily adhered to an outer peripheral surface of a nitride of a flaky particle. Sectional drawing which shows the structure made to do.

FIG. 4 is a schematic diagram showing a reciprocating frictional resistance test apparatus for testing the lubricity of a water-soluble release agent.

5 is a graph showing the results of a reciprocating frictional resistance test of the water-soluble release agent according to the present invention and Comparative Examples 1 and 2, using the apparatus of FIG.

FIG. 6 is a schematic diagram showing a vortex tester for testing the lubricity of a water-soluble release agent, (A) is a plan view of its lower mold,
(B) is a sectional view along the line VI-VI.

7 is a graph showing the flow lengths of the water-soluble mold release agents according to the present invention (products of the present invention 2, 3) and the melts of Comparative Examples 3 and 4 using the vortex tester of FIG.

FIG. 8 is a graph showing the effect of the particle size of spherical particles on lubricity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scale-like particle 2 Spherical particle 3 Air layer 5 Nitride coating

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keiji Gobongami 3-45 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Inside Hanano Shoji Co., Ltd. (72) Takashi Hanano 3-chome Takatsukadai, Nishi-ku, Kobe-shi, Hyogo 2nd 45 Hanano Trading Co., Ltd.

Claims (5)

[Claims] 1. When a water-soluble release agent for die-casting containing at least flaky particles and spherical particles is applied to the surface of a mold, the spherical particles intervene between the flat surfaces of the adjacent flaky particles. A film structure of a water-soluble mold release agent for die casting, wherein the film structure has a laminated structure in which a space is provided between the flaky particles, and an air layer is formed in the space. 2. The flat surface of the scale-like particles on the surface of the mold by dispersing the active ingredient in the form of scale-like particles having a flat surface, spherical particles, and a binder, and dispersing them in a solution and applying the solution to a mold. A water-soluble release agent, wherein the spherical particles and air are mixed in between to form an air layer. 3. The water-soluble release agent according to claim 2, wherein a nitride coating is applied to an outer periphery of said flaky particles. 4. The water-soluble release agent according to claim 2, wherein the spherical particles are previously adhered to the flat surface of the flaky particles before being applied to the mold. . 5. The water-soluble release agent according to claim 2, wherein the particle size of the flaky particles is 5 to 30 μm.