JP2022125857A - powder release agent - Google Patents

Abstract

To provide a powder release agent having a form of being impregnated or involved with a lubricating liquid and, by using amorphous silica as a substance covering the lubricating liquid, suppressing the generation of gases upon application and, when being applied to a cavity wall face of a mold, capable of forming an applied film uniform and high in adhesion.SOLUTION: A powder release agent is applied to a cavity wall face of a casting mold, is composed of a lubricating liquid and spherical porous silica, and includes powder particles obtained by impregnating the spherical porous silica with the lubricating liquid as an effective component.SELECTED DRAWING: None

Description

The present invention relates to a powder release agent for die casting.

Die casting is a casting method that can mass-produce high-precision metal parts efficiently and economically by injecting molten metal (molten metal) into a mold with a complicated shape at high speed and high pressure. During die casting, die casting mold release agents are used to cool overheated molds, prevent sticking (seizure) between injected metal and molds, and reduce resistance when removing castings from molds (mold release resistance). is applied to the inner surface of the mold.

Die-cast release agents are broadly classified into solvent-type agents in which active ingredients are dissolved or dispersed in a solvent, and solvent-free agents in which no solvent is used. Furthermore, the solvent type includes an aqueous type using water as a solvent and an oily type using a hydrocarbon liquid as a solvent.

The active ingredients of die casting release agents include not only substances that are liquid at room temperature, such as lubricating mineral oils, oils and fats, and silicone oils, but also powdery substances that are solid at room temperature, such as inorganic powder, graphite, and wax. sometimes used. Since die casting requires a variety of manufacturing equipment, types of metals, and other conditions, die casting mold release agents are blended as needed with active ingredients that have properties that suit the various casting conditions at the manufacturing site. .

Aiming to efficiently coat the active ingredient on the inner surface of the mold, so-called solvent-type mold release agents using dissolution or dispersion of the active ingredient in a solvent are currently mainstream. In particular, water-based mold release agents, which use water as a solvent, are widely used as a mainstream mold release agent because they are not only flame-retardant, but also have a significant cooling effect on the mold that is overheated during the manufacturing process. It is Release agents that use solvents other than water (mainly hydrocarbon solvents) are called oil-based release agents. However, due to the flammability and other properties of the solvent itself, there are major problems in terms of equipment and safety. .

On the other hand, in line with the development of manufacturing equipment technology, including internal cooling technology for molds, we have also developed solvent-free die-cast mold release agents that do not use solvents for mold cooling and efficient application of mold release agents. progressed. In particular, a powder type die-cast release agent that is sprayed with a powder release agent is expected to be an effective method for improving environmental friendliness and product quality from the aspect of the release agent.

JP-A-03-243242 Japanese Patent No. 6613683 JP 2010-264466 A

Solvent-based, water-based mold release agents that are currently mainstream contain water as a solvent, as the name suggests. Therefore, when a water-based mold release agent is applied to the inner surface of the mold, moisture often remains on the inner surface of the mold. In such a case, residual moisture on the inner surface of the mold may be taken into the inside of the molten metal poured into the mold cavity and vaporized, resulting in the formation of blowholes in the casting. In addition, if the Leidenfrost phenomenon occurs when the water-based mold release agent comes into contact with the high-temperature mold, the active ingredient may not adhere to the inner surface of the mold, and the mold release agent may not perform its intended function. . In addition, when water-based release agents are used, wastewater treatment equipment is required to avoid environmental risks stemming from used water-based release agents. Moreover, ongoing operating costs are unavoidable. As described above, many problems are still pointed out even in the case of using a solvent-type aqueous release agent, which is currently the mainstream.

On the other hand, when a powder-type release agent is used, the problems caused by using a solvent-based water-based release agent as described above do not occur. However, the powder-type release agent also has various problems, and the current situation is that it has not necessarily spread.

As a powder-type release agent, Patent Document 1 discloses a powder-type release agent obtained by mixing an organic substance that imparts adhesiveness to a powder or granular inorganic compound. It is obtained by mixing an inorganic powder such as boron nitride or mica that exhibits releasability with an organic substance such as a metal soap or a polymer compound as a binder component. However, the release agent according to this embodiment has a fragile release agent layer formed on the inner surface of the mold, so when the molten metal injection speed becomes high, the release agent layer breaks and peels, resulting in poor demolding and seizure. There is a possibility of inviting a productivity fall. In addition, since the main active ingredient is colored and opaque inorganic powder, it is extremely difficult to maintain a favorable working environment.

In Patent Document 2, a main component particle containing a modified silicone oil as a lubricating liquid and having a main body formed in a solid particle shape at room temperature is provided, and the main body is composed of an organic substance such as wax or resin. A powder release agent is disclosed. However, the powder release agent according to the present embodiment has a complicated manufacturing process, and the organic substance itself that constitutes the main body gasifies when it comes into contact with the molten metal, which is one of the factors that cause poor quality of cast products. We are anxious about producing a blowhole.

As a powder release agent encapsulating a lubricating liquid, there has been reported a release agent in which silicone oil is encapsulated in hollow spherical ceramic particles (Patent Document 3). In the production of the powder release agent according to the present embodiment, high-temperature firing is required for the production of ceramic particles, and it is required to precisely mold a structure that can hold/release the required amount of silicone oil. There is a problem that the manufacturing process of the template itself becomes extremely complicated.

The present invention has high releasability and easy handling, is expected to suppress contamination of the mold and its surroundings, generates less gas that causes blowholes, which is one of the causes of poor quality of cast products, and An object of the present invention is to provide a powder release agent that is easy to manufacture.

The powder release agent of the present invention is a powder release agent that is applied to the inner surface of a die casting mold, and is composed of a lubricating liquid and spherical porous silica, and the spherical porous silica is impregnated with the lubricating liquid. It is characterized by containing retained powder particles as an active ingredient.

Preferably, the lubricating liquid is one or more selected from silicone oil, mineral oil and synthetic oil.
The spherical porous silica is preferably composed of amorphous silica.

The powder release agent of the present invention preferably contains a spreading agent in addition to the lubricating liquid in addition to the spherical porous silica.
The angle of repose of the powder release agent is preferably less than 70°.

According to the present invention, by using a specific spherical porous silica as a substance to be impregnated with a lubricating liquid, it can be expected to suppress the generation of decomposable gas that causes quality defects in castings, and is easy to handle at room temperature. It is possible to provide a powdery mold release agent that can be easily produced by a simple operation and that achieves excellent mold adhesion and mold releasability during die casting.

Schematic diagram for explaining the releasability test procedure

The powder release agent of the present invention and the method for producing the same will be described in detail below.
The powder release agent of the present invention is composed of spherical porous silica and a lubricating liquid, and is characterized by containing powder particles in which the spherical porous silica is impregnated with the lubricating liquid as an active ingredient.
The spherical porous silica retains a lubricating liquid inside and exhibits high fluidity as a powder in a normal temperature range. Therefore, by including powder particles in which the spherical porous silica is impregnated with a lubricating liquid as an active ingredient of the powder release agent, the release agent storage tank and the pipeline leading to injection into the mold A high degree of blockage avoidance.
On the other hand, from the powder release agent of the present invention that has reached the inner surface of the mold, contact with a high-temperature mold or rapid temperature rise due to introduction of molten metal is triggered, and the lubricating liquid contained in the powder particles is powdered. The lubricating liquid expands and spurts outside the body, and the lubricating liquid is uniformly and quickly supplied to the inner surface of the mold, thereby exhibiting excellent releasability. The mold inner surface is also referred to as the cavity wall surface of the mold.

The average particle size of spherical porous silica is usually 0.5 to 100 μm. If the average particle size of the spherical porous silica is less than 0.5 μm, not only is the handleability lowered, but it also becomes difficult to preserve the working environment for workers. On the other hand, if the average particle size exceeds 1000 μm, the smoothness of the inner surface of the mold is lowered due to adhesion of the powder release agent, which adversely affects the surface quality of the casting. Therefore, the average particle size of spherical porous silica to be used is preferably 1 to 100 μm. Examples of the spherical porous silica include Sunsphere (manufactured by AGC Si Tech Co., Ltd.), God Ball (manufactured by Suzuki Yushi Kogyo Co., Ltd.) and Microid (ultrafine powder silica, manufactured by Tokai Chemical Industry Co., Ltd.). is mentioned. Among these, Sunsphere is spherical amorphous silica that does not contain crystalline silica, and is preferable because it has excellent fluidity and oil absorbency and is easy to handle from the viewpoint of ensuring the preservation of the working environment.

Silicone oil, mineral oil, synthetic oil, or the like is used as the lubricating liquid.
Straight silicone oils such as polydimethylsiloxane and polymethylphenylsiloxane, and modified silicone oils can be used as the silicone oil. Modified silicone oils that can be used include organopolysiloxanes at least partially modified with alkyl groups, aralkyl groups, carboxylalkyl groups, carboxylic acid alkyl groups, hydroxyalkyl groups, aminoalkyl groups, and the like.

Common mineral oil is used as the base oil of the lubricating liquid. Examples include paraffinic mineral oils and naphthenic mineral oils. The kinematic viscosity (100° C.) of these mineral oils is usually 5-600 mm ² /s.

Synthetic oils include fatty acids obtained from fats and oils such as beef tallow, lard, rapeseed oil, coconut oil, palm oil, bran oil, or hydrogenated products thereof; esters of fatty acids and alcohols; poly-α-olefins such as polybutene; polyols such as glycol or polyester polyols; other polyethers; polyesters; higher alcohols;

The lubricating liquids described above may be used alone, or two or more of them may be used in combination.

Among these, it is preferable to use silicone oil from the viewpoint of exhibiting excellent releasability.

In the powder particles of the present invention, the weight ratio of spherical porous silica to lubricating liquid (spherical porous silica/lubricating liquid) is preferably 30/70 to 95/1, more preferably 45/55 to 90/10.

When the ratio of the spherical porous silica/lubricating liquid in the powder particles exceeds 30/70 and the lubricating liquid ratio is increased, the fluidity is remarkably lowered when the powder particles are blended with the powder release agent, resulting in As a result, problems such as clogging in the piping and uneven coating of the release agent are caused.
On the other hand, when the spherical porous silica/lubricating liquid ratio is less than 95/1 and the lubricating liquid ratio decreases, sufficient releasability cannot be obtained.

The powder release agent is made of spherical porous silica particles impregnated with a lubricating liquid, and ensures adhesion to a wide range of mold temperatures, including cooling molds, which are being developed in recent years. Therefore, it is preferable to further contain a spreading aid. An organic material that is solid at room temperature and that melts or softens due to the heat of the mold corresponds to the spreading aid.

Examples of spreading aids include synthetic waxes such as paraffin wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax, N,N'-ethylenebisoleic acid amide and N,N'-ethylenebisstearic acid amide. and natural waxes such as beeswax, carnauba wax and montan wax. Thermoplastic resins such as polytetrafluoroethylene, acrylic resin, methacrylic resin, polyvinyl acetate, polyurethane, polystyrene, polyvinylidene fluoride, polycarbonate, and acrylonitrile styrene resin may also be used.
The spreading aid can be added as long as it does not affect the quality of the casting, but the weight ratio of the powder particles to the spreading aid is preferably 50/50 to 99/1, preferably 70/30. ~90/10 is more preferred.

The powder release agent preferably has an angle of repose of less than 70°, more preferably 40° or less, which is an indicator of powder fluidity. In the present specification, the angle of repose is a value measured by an injection method using a funnel conforming to JIS K6911.5.2 and a drop height of 90 mm for a powder release agent vacuum-dried at 50° C. for 8 hours or more. is.

As a method for producing powder particles in which spherical porous silica is impregnated with a lubricating liquid, the lubricating liquid is diluted with a solvent, the diluted liquid is allowed to permeate the porous silica, and the solvent is volatilized by drying gradually. A known method, such as a method of impregnating the inside of the porous silica with a lubricant, or a method of immersing the porous silica in the lubricant and forcibly infiltrating the lubricant into the porous silica by vacuuming. can be used.

The powder release agent includes, in addition to powder particles composed of spherical porous silica and a lubricating liquid, an appropriate amount of the spreading aid described above, and a general A release component, a dispersant component, and other additive components contained in the lubricating fluid may also be included.

In one embodiment of the method for producing powder particles of the present invention, a low-polarity organic solvent and a lubricating liquid are used in an amount of 1.0 to 10 times the weight of the spherical porous silica and 0.05 to 3.0 times the weight of the lubricating liquid. and are mixed and stirred until uniform to obtain a dispersion. Next, when the low-polarity organic solvent is removed from the dispersion under reduced pressure by an evaporator, powder particles in which the lubricating liquid is uniformly absorbed by the spherical porous silica can be obtained substantially quantitatively. The obtained powder particles did not generate agglomerates, and even when observed with a scanning electron microscope (SEM), no change in appearance was observed between the spherical porous silica before oil absorption and the powder particles. In other words, it can be said that the powder particles in the present invention are powders that are smooth and easy to handle.

Hexane, petroleum ether, diethyl ether, toluene, tetrahydrofuran, and the like can be selected as the low-polarity organic solvent used for producing the powder particles. By using these low-polarity organic solvents, it is possible to obtain a solvent dispersion of the lubricating liquid with high uniformity, and therefore it is possible to produce powder particles that are homogeneous and do not easily form agglomerates.

EXAMPLES The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to these examples and the like.
[Preparation of powder release agent]
Powder release agents were prepared according to Examples 1-12 and Comparative Examples 1-4.
[Evaluation of powder release agent]

(1) Releasability The presence or absence of seizure of aluminum on a steel plate (material: SKD61) heated to 250°C and 300°C was evaluated. Test conditions are shown in Table 1 below.

Also, the test operation procedure was as shown in FIG. Also, the test operation procedure was as shown in FIG. That is, (1) a water-based release agent is applied by spraying, (2) a cylindrical jig is installed and molten aluminum is introduced, (3) a load is applied and pulled horizontally, and this is done. It was possible to pull without sticking, and the releasability was judged according to the maximum value of the load required for pulling.
(Releasability evaluation criteria: conditions at 250°C)
O: The release resistance value was less than 4.5 kg.
Δ: The release resistance value was 4.5 Kg or more and less than 6.0 Kg.
x: The release resistance value was 6.0 kg or more.
(Releasability evaluation criteria: 300°C conditions)
◯: The release resistance value was less than 12 kg.
Δ: The release resistance value was 12 Kg or more and less than 22 Kg.
x: The release resistance value was 22 kg or more, which was equal to or higher than the upper limit of the release resistance.

(2) Adhesion A steel plate (100 mm × 100 mm) heated to 250 ° C. is coated with 0.5 g of a powder release agent from a position 20 cm away using a powder coating spray gun, and adhered to the steel plate. The adhesion amount of the powder release agent was measured.

(3) Soiling The appearance of the steel sheets used in the above-mentioned (2) adhesion test was visually evaluated.
〇: Colorless or pale white △: Dark white ×: Opaque coloring other than white

(4) Angle of repose Measured by an injection method using a funnel conforming to JIS K6911.5.2 and a drop height of 90 mm.
A powder release agent is dropped from a funnel of a certain height onto a horizontal substrate through a 710 μm sieve, and the angle formed by the generatrix of the powder release agent deposited conically on the substrate and the substrate surface. was measured as the angle of repose.
Measuring device: Angle of repose measuring instrument ASK-01 (manufactured by AS ONE Corporation)
(Repose angle evaluation criteria)
Good: The angle of repose was 30° or more and less than 50°.
Δ: The angle of repose was 50° or more and less than 70°.
x: The angle of repose was 70° or more.

[Example 1]
48 parts by weight of Sunsphere H-52 (manufactured by AGC Si Tech Co., Ltd.), 100 parts by weight of diethyl ether, BY16-799 (dimethyl silicone oil (80 mm ² /s), manufactured by DuPont Toray Specialty Materials Co., Ltd. ) 32 parts by weight, after mixing and stirring, diethyl ether was removed under reduced pressure to obtain powder particles. Further, 20 parts by weight of AC-392 (oxidized polyethylene wax, manufactured by Honeywell International) was added to prepare a powder release agent.
Table 2 shows the evaluation results of the powder release agent of Example 1.

[Examples 2 to 4]
SH-550 (methylphenyl silicone oil (125 mm ² /s), manufactured by DuPont Toray Specialty Materials Co., Ltd.) was used in place of BY16-799 (dimethyl silicone oil (80 mm ² /s)) in Example 1. (Example 2), TN (organopolysiloxane (1200 mm ² /s), manufactured by Asahi Kasei Wacker Silicone Co., Ltd.) (Example 3), or X42-C5615 (organopolysiloxane (5400 mm ² /s), Momentive A powder release agent was prepared in the same manner as in Example 1, except that (Example 4) was used (manufactured by Performance Japan LLC).
Table 2 shows the evaluation results of the powder release agents of Examples 2-4.

[Example 5]
In Example 3, the amount of Sunsphere H-52 (manufactured by AGC Si Tech Co., Ltd.) was changed from 40 parts by weight to 26 parts by weight, and TN (organopolysiloxane (1200 mm ² /s), Asahi Kasei Wacker Silicone Co., Ltd. A powder release agent was prepared in the same manner as in Example 3, except that the amount of ) was changed from 32 parts by weight to 54 parts by weight.
Table 2 shows the evaluation results of the powder release agent of Example 5.

[Example 6]
In Example 5, the amount of Sunsphere H-52 (manufactured by AGC Si Tech Co., Ltd.) was changed from 26 parts by weight to 40 parts by weight, and TN (organopolysiloxane (1200 mm ² /s), Asahi Kasei Wacker Silicone Co., Ltd. A powder release agent was prepared in the same manner as in Example 5, except that the amount of ) was changed from 54 parts by weight to 40 parts by weight.
Table 2 shows the evaluation results of the powder release agent of Example 6.

[Example 7]
In Example 6, the amount of Sunsphere H-52 (manufactured by AGC Si Tech Co., Ltd.) was changed from 40 parts by weight to 72 parts by weight, and TN (organopolysiloxane (1200 mm ² /s), Asahi Kasei Wacker Silicone Co., Ltd. A powder release agent was prepared in the same manner as in Example 6, except that the amount of ) was changed from 40 parts by weight to 8 parts by weight.
Table 2 shows the evaluation results of the powder release agent of Example 7.

[Example 8]
In Example 7, the amount of Sunsphere H-52 (manufactured by AGC Si Tech Co., Ltd.) was changed from 72 parts by weight to 76 parts by weight, and TN (organopolysiloxane (1200 mm ² /s), Asahi Kasei Wacker Silicone Co., Ltd. A powder release agent was prepared in the same manner as in Example 7, except that the amount of ) was changed from 8 parts by weight to 4 parts by weight.
Table 2 shows the evaluation results of the powder release agent of Example 8.

[Example 9]
In Example 8, the amount of Sunsphere H-52 (manufactured by AGC Si Tech Co., Ltd.) was changed from 76 parts by weight to 40 parts by weight, and TN (organopolysiloxane (1200 mm / s), Asahi Kasei Wacker Silicone Co., Ltd. (manufactured by Honeywell International) was changed from 4 parts by weight to 10 parts by weight, and AC-392 (polyethylene wax manufactured by Honeywell International) was changed from 20 parts by weight to 50 parts by weight. to prepare a powder release agent.
Table 2 shows the evaluation results of the powder release agent of Example 9.

[Example 10]
In Example 7, the amount of TN (organopolysiloxane (1200 mm ² /s), Asahi Kasei Wacker Silicone Co., Ltd.) was changed from 8 parts by weight to 18 parts by weight, and AC-392 (polyethylene oxide wax, Honeywell International) A powder release agent was prepared in the same manner as in Example 7, except that 20 parts by weight was changed to 10 parts by weight.
Table 3 shows the evaluation results of the powder release agent of Example 10.

[Example 11]
100 parts by weight of diethyl ether and 26 parts by weight of TN (organopolysiloxane (1200 mm ² /s), Asahi Kasei Wacker Silicone Co., Ltd.) are added to 54 parts by weight of Sunsphere H-52 (manufactured by AGC Si Tech Co., Ltd.). After mixing and stirring, diethyl ether was removed under reduced pressure to obtain powder particles. Further, 20 parts by weight of aluminum stearate 600 (polyethylene oxide, manufactured by NOF Corporation) was added to prepare a powder release agent.
Table 3 shows the evaluation results of the powder release agent of Example 11.

[Example 12]
Same as Example 11, except that calcium stearate (calcium stearate, manufactured by NOF Corporation) was used instead of aluminum stearate 600 (aluminum stearate, manufactured by NOF Corporation). to prepare a powder release agent.
Table 3 shows the evaluation results of the powder release agent of Example 12.

[Comparative Examples 1 and 2]
A powder release agent of Comparative Example 1 was prepared by mixing 20 parts by weight of AC-392 (polyethylene wax, manufactured by Honeywell International) and 80 parts by weight of graphite.
A powder release agent of Comparative Example 2 was prepared by mixing 20 parts by weight of AC-392 (polyethylene wax, manufactured by Honeywell International) and 80 parts by weight of talc.
Table 3 shows the evaluation results of the powder release agents of Comparative Examples 1 and 2. Comparative Example 1 using graphite as a lubricating component showed releasability and handleability (angle of repose) comparable to those of the examples of the present invention. Deterioration of the working environment due to scattering of dust is inevitable. In Comparative Example 2, in which talc, which is an amorphous inorganic fine powder with high adhesion, was used as a solid lubricant, handling properties (angle of repose) comparable to those of Examples were exhibited. was found to be insufficient.

[Comparative Example 3]
20 parts by weight of AC-392 (oxidized polyethylene wax, manufactured by Honeywell International) and 80 parts by weight of Sunsphere H-52 (manufactured by AGC Si Tech Co., Ltd.) were mixed to prepare the powder release agent of Comparative Example 3. was prepared.
Table 3 shows the evaluation results of the powder release agent of Comparative Example 3. It was confirmed that when spherical porous silica, which is not impregnated with a lubricating liquid, is blended as powder particles, sufficient release performance is not exhibited.

[Comparative Example 4]
100 parts by weight of diethyl ether, TN (organopolysiloxane (1200 mm ² /s), Asahi Kasei Wacker 10 parts by weight of Silicone Co., Ltd.) was added, mixed and stirred, and then diethyl ether was removed under reduced pressure to obtain powder particles. Further, 10 parts by weight of AC-392 (oxidized polyethylene wax, manufactured by Honeywell International) was added to prepare a powder release agent of Comparative Example 4.
Table 3 shows the evaluation results of the powder release agent of Comparative Example 4. When powder particles were prepared using diatomaceous earth instead of spherical porous silica, it was possible to prepare a powder release agent composition that satisfies the required handleability (angle of repose), but sufficient release performance was not obtained. was confirmed not to express

Claims (4)

A powder mold release agent applied to the cavity wall surface of the casting mold,
1. A powder release agent comprising a lubricating liquid and spherical porous silica, and containing powder particles in which the spherical porous silica is impregnated with a lubricating liquid as an active ingredient. The powder release agent according to claim 1, wherein the lubricating liquid is one or more selected from silicone oil, mineral oil and synthetic oil. 3. The powder release agent according to claim 1, wherein the powder particles have a weight ratio (spherical porous silica/lubricating liquid) of 30/70 to 99/1 between the spherical porous silica and the lubricating liquid. The powder release agent according to any one of claims 1 to 3, wherein the spherical porous silica further contains a spreading aid in addition to the lubricating liquid.

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