JP2023158917A - Mold-release agent for die casting - Google Patents

Abstract

To provide a mold-release agent for die casting that has high stability, improves the abilities to adhere to and be released from a metal mold, and has high safeness.SOLUTION: A mold-release agent for die casting comprises a W/O-type emulsion containing 20-90 mass% of base oil, 1-50 mass% of a silicone compound having a molecular skeleton formed with siloxane bond, 3-20 mass% of basic sodium sulfonate, and 1-30 mass% of water.SELECTED DRAWING: Figure 3

Description

The present invention relates to a mold release agent for die casting. More specifically, the present invention relates to a mold release agent applied to the mold surface of a mold cavity of a metal mold during die casting.

Die-cast products have extremely high dimensional accuracy and excellent cast surface smoothness. Die-cast products using aluminum alloys, magnesium alloys, zinc alloys, etc. are produced in large quantities. In the process of manufacturing die-cast products, a mold release agent is used to improve the releasability between the mold and the die-cast product. A mold release agent is a liquid composition containing a mold release component in a dispersion medium, and is sprayed onto a heated mold. The dispersion medium is evaporated by the heat of the mold, and a film of a mold release component is formed on the mold surface, thereby exhibiting mold release properties.

As a mold release agent for die casting, an O/W type (under water) is prepared by emulsifying and dispersing water-insoluble mold release components such as silicone compounds, vegetable oils, mineral oils, waxes, fats and oils, and synthetic oils in water using an emulsifier. Oil-based emulsion mold release agents are commonly used. The mold release agent for O/W emulsions is also called a water-based die casting mold release agent. In conventional die casting, an aqueous die casting mold release agent is diluted 50 to 200 times with water, and the diluted solution is usually sprayed onto a mold at a temperature of 100 to 400°C. The proportion of the mold release component contained in the diluent was often less than 1%.

When the temperature of the mold is as high as 300° C. or higher, the so-called Leidenfrost phenomenon is likely to occur. The Leidenfrost phenomenon occurs when water evaporates explosively on a hot mold, creating a layer of water vapor between the mold release agent and the mold, making it difficult for the mold release agent to come into contact with the mold. This is a phenomenon in which the mold release component becomes difficult to adhere to the mold. As a countermeasure to this phenomenon, a diluted solution of an aqueous die-casting mold release agent has been used as cooling water in order to cool the mold to a temperature of 200° C. or lower, at which the mold release component tends to adhere. For this reason, a diluted mold release agent solution is sprayed onto the mold in an excess amount compared to the required amount as a mold release agent, and most of the sprayed diluted mold release agent solution becomes waste liquid.

In addition, when using a water-based mold release agent diluted solution, the moisture is ultimately removed from the mold by air blowing, but if moisture remains in the mold, cavities will occur in the casting, resulting in defective die casting. occurs. Patent Document 1 describes that a dispersant is added to an aqueous die-casting mold release agent to improve drying properties. However, since a large amount of mold release agent is sprayed as in the past, there has been a need for an improvement in suppressing the amount of water remaining on the mold.

Furthermore, when using a mold release agent for die casting, if the amount of mold release component attached to the mold is insufficient, mold release properties will be poor. On the other hand, if the amount of adhesion is excessive, the excess mold release component will be decomposed by heat and mixed into die-cast products as decomposed gas, causing an increase in the number of defective products. The conventional method of spraying a large excess of diluted aqueous die casting mold release agent can increase the amount of mold release component deposited, but the temperature change of the mold during the casting cycle is large, resulting in increased adhesion to the mold. There was a problem in that it was difficult to control the amount of the mold release component. Additionally, there was a concern that metal fatigue caused by repeated large temperature changes could shorten the lifespan of the mold.

On the other hand, non-emulsion type release agents for die casting are also known. Patent Document 2 discloses an oil-based mold release agent for die casting in which a water-insoluble mold release component is dissolved in a solvent or the like. However, oil-based mold release agents for die-casting have a flash point, so there is a risk of fire outbreak, so they have not been widely used.

Japanese Patent Application Publication No. 2006-212691 Patent No. 4095102

The present invention has been made in view of the above-mentioned problems of the prior art, and provides a mold release agent for die casting that is highly stable, has improved adhesion to molds and mold release properties, and is highly safe. The purpose is to

As a result of repeated research to solve the above-mentioned problems of the prior art, the present inventors have discovered that a mold release agent for a W/O type (water-in-oil) emulsion having a specific composition can be used without diluting it through a mist nozzle. Surprisingly, the inventors have found that the above object can be achieved by spraying the mold onto the mold using the above-described method, and have completed the present invention.

The mold release agent for die casting according to the present invention contains a base oil, a silicone compound having a molecular skeleton formed by siloxane bonds, basic sodium sulfonate, and water in proportions within a specific range. Additives other than these may also be included. The total content of base oil and silicone compound in the mold release agent for die casting is greater than the content of water. The mold release agent for die casting according to the present invention is a mold release agent composed of a W/O emulsion in which water droplets are present in oil.

According to the present invention, a mold release agent containing a high proportion of a mold release component can be used by spraying a small amount. According to the present invention, the occurrence of the Leidenfrost phenomenon is suppressed, and it becomes possible to efficiently attach a mold release component to a mold. According to the present invention, the temperature change (cooling width) of the mold during repeated die casting is small, and the mold can be easily dried. Moreover, since the amount used can be significantly reduced compared to conventional aqueous mold release agents for die casting, the amount of waste liquid is reduced, making it possible to improve environmental pollution problems such as water pollution.

In addition, the mold release agent for die casting of the present invention avoids the risk of fire, which is a problem with oil-based mold release agents, and suppresses the generation of mist from evaporated solvent components. It also leads to improvement of the environment.

FIG. 1 is a graph showing the results of the adhesion evaluation test. FIG. 2 is an image showing the results of the adhesion evaluation test. FIG. 3 is a graph showing the results of the deposition evaluation test.

[Overview of embodiment]
The mold release agent according to the present invention is composed of a W/O emulsion in which water droplets are present in oil. Water-in-oil emulsions are also called inverse emulsions. The mold release agent according to the present invention can contain about 70 to 90% by mass of an active ingredient (mold release component) as a mold release agent. Therefore, the active ingredient concentration is very high compared to conventional aqueous emulsion type mold release agents. It also has no flash point and is highly safe.

The mold release agent according to the present invention generally contains a base oil, a silicone compound, basic sodium sulfonate, and water. The base oil and silicone compound are oily components and are thought to function as mold release components. Basic sodium sulfonate is an emulsifier component and is thought to have the function of dispersing water in oily components. Water is thought to have the function of eliminating the flammability of the mold release agent and lowering the kinematic viscosity of the mold release agent. Water also serves to cool the mold when a mold release agent is used.

The mold release agent according to the present invention contains 20 to 90% by mass of base oil. Specific examples of the base oil include mineral oils such as turbine oil, machine oil, cylinder oil, paraffin oil, and gear oil, synthetic oils such as polybutene, polybutadiene, and polyester, and solvents such as organic solvents. These may be used alone or in combination of two or more.

When using an organic solvent as the base oil, specific examples thereof include petroleum-based hydrocarbon solvents. Examples of petroleum hydrocarbon solvents include paraffin hydrocarbon solvents, olefin hydrocarbon solvents, naphthenic hydrocarbon solvents, aromatic hydrocarbon solvents, mineral hydrocarbon solvents, and the like. Among these petroleum-based hydrocarbon solvents, it is preferable to use paraffin-based hydrocarbon solvents from the viewpoint of health issues for workers, chemical stability, and the like. Note that as the petroleum-based hydrocarbon solvent, the above solvents may be used alone or in combination. Further, the petroleum-based hydrocarbon solvent may contain additives, impurities, etc. within a range that does not go against the spirit of the present invention.

The physical properties of the base oil are not limited as long as the effects of the present invention are achieved, but for example, a petroleum-based hydrocarbon solvent having a flash point of 70 to 170°C can be used. If a base oil with a flash point of 70° C. or higher is used, it will dry quickly and the thickness of the release component film formed on the mold surface will be uniform. In addition, variations in dimensions of the casting due to mold seizure and deposition of mold release components are suppressed. Further, as the upper limit of the range, the flash point is preferably 170° C. or lower from the viewpoint of having appropriate volatility. If the drying property (volatility) of the mold release agent is low and the mold release agent remains in the mold, it may cause dripping of the mold release agent from the mold and formation of cavities in the casting.

The mold release agent according to the present invention contains 1 to 50% by mass of a silicone compound having a molecular skeleton formed by siloxane bonds. Examples of silicone compounds include alkyl-modified silicones such as dimethyl silicone and α-olefin-modified silicones, aralkyl-modified silicones such as phenyl-modified silicones and α-methylstyrene-modified silicones, carboxy-modified silicones, alkyl-aralkyl co-modified silicones, and alkyl-esters. Examples include various modified silicones such as modified silicone.

The kinematic viscosity of the silicone compound is not limited as long as it achieves the effects of the present invention, but the lower limit of the kinematic viscosity at 25°C is preferably 100 mm ² /s or more, more preferably 500 mm ² /s or more, and the upper limit is preferably 5000 mm ² /s or less, more preferably 3000 mm ² /s or less. When the kinematic viscosity of the silicone compound is lower than 500 mm ² /s, seizure defects are likely to occur. When the kinematic viscosity of the silicone compound is higher than 3000 mm ² /s, it becomes difficult to form a stable W/O emulsion.

Basic sodium sulfonate is contained in the mold release agent according to the present invention in an amount of 3 to 20% by mass. In the present invention, by using basic sodium sulfonate, which is an anionic surfactant, as an emulsifier, water can be uniformly dispersed in an oil phase composed of a base oil and a silicone compound, and the viscosity is low. It has been discovered that a mold release agent can be obtained. When the content of basic sodium sulfonate is less than 3% by mass, it is difficult to produce a stable W/O emulsion, and when it exceeds 20% by mass, the viscosity of the emulsion increases and storage stability decreases. This is not desirable because it can cause From the viewpoint of emulsion stability, the content of basic sodium sulfonate is preferably 4% by mass or more, more preferably 5% by mass or more. The content of basic sodium sulfonate is preferably 17% by mass or less, more preferably 13% by mass or less. The basic sodium sulfonate may be dissolved in base oil or the like.

As the basic sodium sulfonate, those having a base number of 100 mgKOH/g or more according to JIS K-2501 are used. Basic sodium sulfonate having a base number of 100 mgKOH/g or more is also referred to as overbased sodium sulfonate or overbased sodium sulfonate. When the base value is less than 100 mgKOH/g, it becomes difficult to produce a stable emulsion. Further, in order to maintain stable mold release performance, the base number is preferably in the range of 200 to 600 mgKOH/g, particularly 300 to 500 mgKOH/g. If the base number exceeds the above range, the solubility in base oil may be poor.

The mold release agent according to the present invention contains 1 to 30% by mass of water. The water content is preferably 5 to 25% by mass. In the mold release agent according to the present invention, water is dispersed in the form of fine particles in the continuous phase of base oil and silicone compound. If the water content is less than 1% by mass, the mold release agent has a flash point, and there is a concern that it may catch fire in a high-temperature environment. If the water content exceeds 30% by mass, the storage stability of the stock solution may be poor and the viscosity of the release agent may increase.

In addition, in order to improve the storage stability of the mold release agent, a known emulsifier suitable for emulsifying the mold release component may be mixed with the basic sodium sulfonate. As the emulsifier, for example, nonionic surfactants such as higher alcohol alkylene oxide adducts, fatty acid alkylene oxide adducts, higher amine alkylene oxide adducts, fatty acid amide alkylene oxide adducts, etc. can be used. The amount of emulsifier used can be selected as appropriate depending on the type of release component, but in order to suppress thickening etc., it should be less than the amount of basic sodium sulfonate and the minimum amount necessary for emulsification and stability. It is preferable to do so. Since the mold release agent according to the present invention does not use a nonionic surfactant or can use only a small amount of nonionic surfactant, the stability of the mold release agent at high and low temperatures is not affected by the cloud point effect. Furthermore, the viscosity of the mold release agent does not increase due to hydrogen bonding, and the clogging of the mist nozzle can be suppressed and the occurrence of problems with poor discharge can be reduced.

Furthermore, the mold release agent according to the present invention can also be used in combination with other chemicals conventionally added to mold release agents for die casting to the extent that adhesion efficiency and mold release properties are not impaired. Examples of such other agents include polymer compounds, waxes, antifoaming agents, corrosion inhibitors, thickeners, rust preventives, preservatives, and the like.

If the viscosity of the mold release agent is low, mist may be generated during casting, so a polymer compound may be added to suppress this. Examples of such polymer compounds include poly(meth)acrylate, polyisobutylene, olefin copolymers (e.g., ethylene-propylene copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer), etc. Those having a number average molecular weight of 2,000 to 300,000, particularly 2,000 to 150,000 are preferably used. The polymer compound is blended in the mold release agent of the present invention in an amount of 0.05 to 20% by mass. When blending a polymer compound, by setting the blending amount to 0.05% by mass or more, it is possible to sufficiently suppress the generation of mist, and by setting the blending amount to 20% by mass or less, clogging of the mist nozzle due to increased viscosity can be prevented. It can be prevented. From this point of view, the blending amount is more preferably 0.1 to 5% by mass.

The mold release agent according to the present invention contains a silicone compound as a mold release component in a proportion of 1 to 50% by mass. Furthermore, the mold release agent contains a base oil that can function as a mold release component in an amount of 20 to 90% by mass. Furthermore, the mold release agent according to the present invention does not need to be diluted and can be used by spraying it onto a mold as it is at this concentration. For this reason, compared to conventional aqueous emulsion type mold release agents, the concentration of active ingredients in the mold release agent when sprayed during die casting can be increased by 100 times or more (specifically, about 140 to 180 times). ) can be increased to

The kinematic viscosity of the mold release agent according to the present invention can be measured in accordance with JIS K 2283 kinematic viscosity test. When measured in this test, the kinematic viscosity of the W/O emulsion according to the present invention is preferably 1 to 40 mm ² /s (40° C.). The mold release agent is sprayed onto the mold using a spray device equipped with a nozzle, and if the viscosity of the mold release agent is high, it may cause clogging of the nozzle. Furthermore, considering the versatility of the die-casting process, it is preferable that the viscosity of the mold release agent is not significantly different from that of conventionally used aqueous die-casting mold release agents. In general, W/O emulsions tend to have high viscosity, and in particular, high-concentration W/O emulsions have high viscosity, so it was thought that they were not suitable for nozzle spraying. On the other hand, the mold release agent according to the present invention is composed of a W/O emulsion having a specific composition, and has a viscosity range that allows nozzle spraying even though it contains a high concentration of mold release component.

[Example]
EXAMPLES Below, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

(Examples 1 to 4 and Comparative Examples 1 to 9)
[Preparation of sample]
A mold release agent for die casting having the composition shown in Tables 1 and 2 was prepared.
Examples 1 to 4 and Comparative Examples 1 to 7 are mold release agents composed of W/O emulsions. Comparative Example 8 is a mold release agent composed of an O/W emulsion. Comparative Example 9 is a non-emulsion oil-based mold release agent.

(Details of ingredients used)
The following materials were used in each sample shown in the table above.
・Silicone compound A: Alkyl/aralkyl modified silicone (alkyl unit 80.8%, aralkyl unit 19.2%), alkyl side chain C = 12, molecular weight 21,000
・Silicone compound B: alkyl/aralkyl modified silicone (alkyl unit 45.5%, aralkyl unit 54.5%), alkyl side chain C = 6, molecular weight 16,000
・Paraffinic solvent (base oil): Isoparaffinic hydrocarbon, density (15°C) 0.82, kinematic viscosity (37.8°C) 12.7mm ² /s
・Rust/corrosion inhibitor: Dibasic acid-based rust/corrosion inhibitor ・Surfactant 1: Basic sodium sulfonate (highly basic synthetic sodium sulfonate, active ingredient 65%, base value 450mgKOH/g), manufactured by LUBRIZOL, product number LZ5318B
・Surfactant 2: Highly basic synthetic calcium sulfonate (active ingredient 55%, base value 400mgKOH/g), manufactured by LUBRIZOL, product number LZ5347LC
・Surfactant 2: Natural sodium sulfonate (neutral), manufactured by MORESCO Co., Ltd., Sulhole S-465, molecular weight 465
・Surfactant 3: Natural calcium sulfonate (neutral), manufactured by MORESCO Co., Ltd., Sulhole CA-45N
・Surfactant 4: Polyoxyalkylene lauryl ether, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., DKS NL-Dash400
・Surfactant 5: Polyoxyalkylene branched decyl ether, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neugen XL
・Surfactant 6: Polyoxyalkylene oleyl cetyl ether, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neugen ET-89
・Surfactant 7: Polyoxyethylene sorbitan monooleate, manufactured by Sanyo Chemical Industries, Ltd., Ionet S-80

The W/O mold release agents of Examples 1 to 4 and Comparative Examples 1 to 7 were produced by the following procedure. The temperature condition was room temperature in all cases.
1. A specified amount of paraffinic solvent was added to the beaker.
2. The beaker was set in a magnetic stirrer (MAGNETIC STIRRER MSR-10S) manufactured by RIKO, and stirred with a stirrer so that the entire mixture was mixed uniformly.
3. Specified amounts of silicone compounds A and B were added and stirred using a magnetic stirrer for about 20 minutes.
4. Specified amounts of various surfactants were added and stirred using a magnetic stirrer for about 20 minutes.
5. A specified amount of a rust/corrosion inhibitor was added, and the mixture was stirred using a magnetic stirrer for about 20 minutes.
6. After visually confirming that the inside of the system had become uniform, the system was stirred using a magnetic stirrer for about 20 minutes while slowly dropping a specified amount of pure water.
7. Furthermore, in order to stabilize the inside of the system, the mixture was stirred using a magnetic stirrer for about 1 hour.

The O/W mold release agent of Comparative Example 8 was produced by the following procedure.
1. Silicone compounds A and B and various surfactants were added in specified amounts to a beaker.
2. The beaker was set in a homogenizer manufactured by Primix Co., Ltd. (HOMOMIXER MARK II Model 2.5), and stirred at 4000 rpm and room temperature for about 30 minutes.
3. Pure water was slowly added to the beaker, and when the viscosity of the system significantly increased, the mixture was stirred with a homogenizer at 4000 rpm and room temperature until the emulsified particle size fell within the designed value. The stirring time was approximately 30 minutes to 1 hour.
4. The designed value of the emulsion particle diameter was controlled to 0.17 μm, and the measurement was performed using Partica LA-960V2 manufactured by HORIBA.
5. After confirming that the emulsified particle size was within the designed value, the remaining pure water was added in its entirety and stirred for about 30 minutes using a homogenizer at 1000 rpm and room temperature.
6. A specified amount of a rust/corrosion inhibitor was added, and the mixture was stirred with a homogenizer at 1000 rpm and room temperature for about 30 minutes.
7. Further, in order to stabilize the inside of the system, the mixture was stirred with a homogenizer at 1000 rpm and room temperature for about 1 hour.

Comparative Example 9 used Lubroren WFR-7R manufactured by Aoki Kagaku Co., Ltd. as an oil-based mold release agent.

[Evaluation: Flammability, kinematic viscosity, stability]
Regarding the mold release agents of Examples 1 to 4 and Comparative Examples 1 to 9, 1. Risk of ignition, 2. Evaluate kinematic viscosity; 3. Stability tests were conducted.

(Evaluation 1: Risk of ignition)
The risk of ignition was evaluated as ◎: nonflammable, ○: flame retardant, and ×: flammable. The standards for nonflammability/flammability/flammability are the flash point determination standard (JIS K 2265), high pressure spray test (Fed.6052/MIL F-7100), and hot manifold test (Fed.6053/MIL A comprehensive judgment was made based on the results of F-7100).

(Evaluation 2: Kinematic viscosity)
The kinematic viscosity (mm ² /s) of each sample at 40° C. was measured in accordance with JIS K 2283 kinematic viscosity test.

(Evaluation 3: Stability)
The stability of each sample was evaluated under the following conditions.
・Evaluation amount: 100mL
- Container: Glass precipitation tube - Cooling-heating conditions: 4°C x 72 hours - 40°C x 72 hours was one cycle.
- Measurement: Each sample contained in a glass sedimentation tube was subjected to 1, 2, and 3 cycles of cooling and heating. Thereafter, the state of the liquid in each sample was visually confirmed. The evaluation criteria were as follows.
〇: The liquid is mixed uniformly and stable ×: The liquid is separated into two layers XX: The liquid is separated into two layers and a precipitate is generated

The evaluation results of flammability risk, kinematic viscosity, and stability are summarized in [Table 3] and [Table 4].

Regarding kinematic viscosity, Comparative Examples 4 to 7 in which a nonionic surfactant was added as an emulsifier had a high kinematic viscosity exceeding 40 mm ² /s. It was thought that the viscosity increased due to hydrogen bonding between the nonionic surfactant and water. If the kinematic viscosity is high, problems such as clogging of a mist nozzle for spraying a mold release agent during die casting or unstable discharge from the nozzle are likely to occur. Examples 1 to 4 had a kinematic viscosity lower than that of the oil-based mold release agent (Comparative Example 9) and close to that of the O/W emulsion mold release agent (Comparative Example 8), and exhibited good properties.

Regarding stability, Examples 1 to 4 containing highly basic sodium sulfonate as an emulsifier were found to be stable. The mold release agents of Examples 1 to 4 stabilize the emulsion by using highly basic synthetic sodium sulfonate (base number 450 mgKOH/g), which is an anionic surfactant, without adding a nonionic surfactant. I was able to convert it into In addition, the stability was insufficient in the examples in which the amount of highly basic sodium sulfonate was 2.6 wt% or less (Comparative Examples 1 and 2) and in the example in which it was 26 wt% (Comparative Example 3).

Regarding stability, although not shown in Table 1, basic calcium sulfonate (active ingredient 55%, base value 400 mgKOH/g) was used in place of high basic sodium sulfonate, and no other surfactants were added. The mold release agent used had insufficient emulsion stability. This was thought to be due to the fact that it was less polar than basic sodium sulfonate, so it was unable to capture water in the system. Therefore, in Comparative Example 4, a nonionic surfactant was blended in addition to basic calcium sulfonate, but no improvement in stability was observed, and separation and precipitates occurred.

Although not shown in Table 2, the release agent for die casting of W/O emulsion using natural sodium sulfonate (neutral) or natural calcium sulfonate (neutral) alone as an anionic surfactant is , the emulsion could not be stabilized. Therefore, in Comparative Examples 5 and 6, natural sodium sulfonate (neutral) or natural calcium sulfonate (neutral) was used in combination with a nonionic surfactant, but stability against heating-cooling cycles was not achieved. Separation and precipitate occurred. Further, the kinematic viscosity was a high value of 47.2 mm ² /s or more. It was thought that this was influenced by hydrogen bonding caused by the nonionic surfactant.

In the W/O type mold release agent for die casting of Comparative Example 7, the stability of the emulsion was improved by using several types of nonionic surfactants in combination. However, the kinematic viscosity was as high as 62.7 mm ² /s, and there were concerns about clogging of the mist nozzle and problems regarding discharge stability. In addition, stability in high and low temperature ranges was affected by the cloud point effect of nonionic surfactants, so stability against heating-cooling cycles was not achieved, resulting in separation and precipitation.

Comparative Example 8 used a stock solution of an oil-in-water (O/W) emulsion mold release agent. In Comparative Example 8, 90% of the mold release agent was water and the content of the nonionic surfactant was about 1 wt%, so the kinematic viscosity was as low as 3.5 mm ² /s. Therefore, it was thought that there would be no problem with spraying from the nozzle. However, when the mold release agent of Comparative Example 8 is sprayed onto a mold, the stock solution is usually diluted 10 to 100 times, so the concentration of the mold release component is less than 1%, and it is necessary to spray a large amount. There is. In addition, when used in a high temperature range for a long period of time, precipitation due to aggregation of silicone compounds is observed near the tip of the mist nozzle, which clogs the mist nozzle and adversely affects stable supply. Comparative Example 8 uses a homogenizer etc. to control the emulsion particle size to 0.17 μm, so it has excellent emulsion stability even in high and low temperature ranges, but it is used in high temperature ranges for a long period of time. Precipitation due to aggregation of silicone compounds was confirmed near the tip of the mist nozzle, which clogged the mist nozzle and adversely affected stable supply.

Since Comparative Example 9 is an oil-based mold release agent mainly composed of silicone oil and a solvent, no separation or precipitate occurred in the stability evaluation test. However, due to the risk of ignition, workability was poor and the working environment was restricted.

[Evaluation: Adhesion and deposition]
Regarding the mold release agents of Example 2 and Comparative Example 8, 4. Adhesion to steel plate, 5. A deposition evaluation test was conducted on steel plates. The steel plate simulates a mold.

(Evaluation 4: Adhesion)
The mold release agents of Example 2 and Comparative Example 8 were applied to a steel plate (100 mm long x 100 mm wide x 10 mm thick, material: SUS304) heated to temperatures of 150°C, 250°C, and 350°C using the following spray equipment and test. It was sprayed under the following conditions and the amount of the release component adhered was measured. In order to exhibit good mold releasability, it is better to have a large amount of adhesion. Note that the mold release agents of Example 2 and Comparative Example 8 were not diluted and were sprayed as undiluted solutions.
・Spraying conditions Nozzle used ATOMAX nozzle AM45B-OST (manufactured by ATOMAX Co., Ltd., two-fluid nozzle)
Air pressure 0.4MPa
Liquid pressure 0.1MPa
Spray time 0.5sec
Spray amount 0.3g
Spray distance 200mm

The results of the adhesion test are shown in [Table 5]. Further, a graph is shown in [FIG. 1], and an image of the adhesion test results is shown in [FIG. 2].

As shown in [Table 5] and [Figure 1], the mold release agent of Comparative Example 8 had a small amount of adhesion at 150°C and 250°C, and at 350°C, it evaporated during spraying and hardly adhered to the steel plate. . On the other hand, the mold release agent of Example 2 showed a sufficiently large amount of adhesion at 150°C, and adhesion to the steel plate was observed even at 350°C.
In addition, the mold release agent of Comparative Example 9, which is an oil-based mold release agent, had a small change in the amount of adhesion at 150° C., 250° C., and 350° C., and adhered stably to the steel plate. However, there was a risk of ignition, and the spraying work had to be carried out in an appropriate environment with fire prevention equipment.

As shown in FIG. 2, in Example 2, it was confirmed that the mold release agent was attached to the entire surface of the steel plate at 150°C. Furthermore, it was confirmed that the mold release agent firmly adhered and spread on the steel plate even in the high temperature range of 250°C and 350°C. On the other hand, in Comparative Example 8, adhesion and spreading of the release agent on the steel plate as in Example 2 could not be confirmed in any temperature range.

(Evaluation 5: Cleanability)
After forming a certain amount of film on the surface of the mold, the mold release agent is used by repeating adhesion, cleaning, and desorption. More specifically, when first sprayed, a strongly adsorbed film is formed on the rough metal surface, which is then peeled off by water pressure washing, and the release agent is sprayed again. Since detachment and adhesion are repeated during these operations, the release agent is required to maintain a constant film thickness without excessively depositing a film.

A steel plate (length 100 mm x width 100 mm x thickness 10 mm, material: SUS304) was heated to 250°C with the mold release agents of Example 2, Comparative Example 8, and Comparative Example 9 under the same conditions as the evaluation of adhesion except for the steel plate temperature. ) was sprayed 5 times at 1 minute intervals, and the deposition rate was evaluated from the amount of the release component attached.
The deposition rate was calculated using the following formula. The smaller the deposition rate, the better the cleaning performance.
Deposition rate (%) = (Amount of adhesion after 5 sprays) / (Amount of adhesion after 1 spray) x 100
The test was conducted with n=2, and the average value was used.

The results of the deposition test are shown in [Table 6]. A graph is also shown in [Figure 3].

As shown in [Table 6], Example 2 exhibited good cleaning performance that was almost equivalent to Comparative Example 9. According to the mold release agent of Example 2, it was possible to achieve both good cleanability and workability, and to reduce the problem of mist nozzle clogging. On the other hand, in Comparative Example 8, agglomeration and precipitation of silicone compounds were observed, and the deposition rate was high. The mold release agent of Comparative Example 8 had an excessively high deposition rate, resulting in poor workability, and there is also a possibility of clogging of the mist nozzle. According to the mold release agent according to the present invention, it is possible to realize a stable W/O type mold release agent composition that exhibits good mold release properties and washability.

It should be understood that the embodiments disclosed herein are illustrative in all respects and are not restrictive in any respect. The scope of the present invention is defined by the claims, and it is intended that all changes within the meaning and range equivalent to the claims are included.

Claims (3)

20 to 90% by mass of base oil,
1 to 50% by mass of a silicone compound having a molecular skeleton formed by siloxane bonds;
3 to 20% by mass of basic sodium sulfonate,
1 to 30% by mass of water,
A mold release agent for die casting, which is composed of a W/O type emulsion containing. The mold release agent for die casting according to claim 1, wherein the basic sodium sulfonate has a base value of 100 mgKOH/g or more. The mold release agent for die casting according to claim 1 or 2, which has a kinematic viscosity (40° C.) of 1 to 40 mm ² /s as measured based on JIS K 2283.