JP2023057208A - Aqueous mold release agent foe die casting - Google Patents

Abstract

To provide a mold release agent for die casting in which gas generation is suppressed, and run properties and heat resistance are improved and usable, whichever of low-speed die casting or high speed die casting the mold release agent is used for.SOLUTION: An aqueous mold release agent for die casting comprises: a laminar silicate mineral; an aromatic carboxylate; and water, in which the laminar silicate mineral (X) is comprised by 0.05<X≤25 mass% and the aromatic carboxylate (Y) is comprised by 0.005<Y≤20 mass% in 100 mass% of the aqueous mold release agent for die casting.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to an aqueous release agent for low-speed/high-speed die casting, and more particularly to an aqueous release agent for die casting with improved hot-water circulation and heat resistance.

Castings of non-ferrous metals such as aluminum are required to have high strength in order to reduce the weight of products. Low-speed casting methods such as laminar flow die casting, in which the molten metal (molten aluminum, etc.) is injected at a slow speed, and squeeze die casting, are less likely to entrain air when the molten metal is injected into the mold, resulting in high-strength castings. , is used as a method for producing such non-ferrous metal castings.

On the other hand, in the casting method described above, since the injection speed of the molten metal is slow, the molten metal solidifies before it is completely filled in the thin-walled part or the end of the mold, and the desired shape cannot be obtained. defects) may occur. In addition, the formation of blowholes due to entrainment of gas accompanying the decomposition of the lubricant also causes a reduction in the strength of the casting.

By the way, in die casting, in order to prevent welding between the mold and the cast product made by solidifying the molten metal, and to easily remove the cast product from the mold without damaging it, the molding surface of the mold is usually coated with a coating during each molding cycle. A release agent is applied. Release agents contain waxes, esters, silicone oils, etc. as lubricating components. Hydrogen-based liquid) and powder type (no solvent) are available. Among these, the aqueous mold release agent is most often used as the die casting mold release agent because it is easy to apply and the mold can be cooled at the same time as the application. For example, in Patent Document 1, an ester carboxylate obtained by an esterification reaction and a neutralization reaction between an aromatic compound having two or more carboxyl groups or a derivative thereof and a compound having 1 to 4 hydroxyl groups is , which has excellent performance as a lubricating component of a water-based mold release agent for die casting, not only at low temperatures but also at high temperatures.

It is also known that adding an inorganic lubricant such as talc, kaolin, graphite, mica, etc. to such a die casting mold release agent improves heat insulating properties and is effective in suppressing poor circulation of molten metal. For example, in Patent Document 2, a combination of a specific clay mineral having thixotropic properties and a specific high-molecular-weight organic compound is used as an aqueous release agent for low-speed injection mold casting, and an ionic repulsion effect is produced there. Aqueous release agents are disclosed which are formulated with water and a dispersant having

JP-A-2002-205139 Japanese Patent No. 4464214

However, even aromatic carboxylic acid esters, which are said to have relatively excellent heat resistance, are not at a level that satisfies the requirements for low-speed die casting, etc., in which heat retention of molten metal is primarily required.
On the other hand, water-based release agents containing clay minerals for the purpose of improving heat retention have problems in terms of maintenance and production efficiency, such as deposits in pipes and clogged nozzles, due to aggregation and sedimentation of clay minerals dispersed in the release agent. likely to occur. Further, the specific high-molecular-weight organic compound and dispersant as described in Patent Document 2 contribute to the stable dispersion of the clay mineral in the undiluted state, but after dilution with water, which is the form actually used, they do not. The above problem cannot be solved because the effect is remarkably reduced.

Therefore, release agents containing clay minerals are generally limitedly used in fields where the heat retention of molten metal is primarily required, especially in low-speed die casting and the like. Therefore, there is a demand for an aqueous mold release agent for die casting which is improved in hot water flowability and heat resistance and which contributes to the improvement of the quality and productivity of aluminum castings.
An object of the present invention is to provide a die casting mold release agent that can be used for both low speed and high speed die casting by being excellent in heat retention of molten metal and realizing improvement in productivity/working environment.

The aqueous mold release agent for die casting of the present invention contains a layered silicate mineral, an aromatic carboxylate, and water, and the layered silicate mineral (X) is It is characterized by containing 0.05% by mass<X≦5% by mass and 0.005% by mass<Y≦20% by mass of the aromatic carboxylate (Y).
The aqueous mold release agent for die casting of the present invention contains a layered silicate mineral with excellent heat insulation and an aromatic carboxylate with high heat resistance, and thus has higher heat insulation. With the above configuration, the present invention can suppress the occurrence of blowholes and contribute to the production of high-quality castings in die-casting for producing cast materials and parts with complicated shapes.

The aqueous release agent for die casting preferably further contains 20% by mass or less of a water-soluble polymer having a weight average molecular weight of 200 to 400,000, if necessary.
By coexisting a specific water-soluble polymer, the fluidity of the aqueous mold release agent is improved, and the instability of the liquid state, etc., which is a concern when the concentration of the aqueous mold release agent for die casting is increased. Problems can be prevented.

The aqueous mold release agent for die casting of the present invention contains a layered silicate mineral, an aromatic carboxylate, a water-soluble polymer having a weight average molecular weight of 200 to 400,000, and water, and 100 mass of the aqueous mold release agent for die casting. %, the layered silicate mineral (X) is 5% by mass <X ≤ 25% by mass, the aromatic carboxylate (Y) is 0.005% by mass <Y ≤ 20% by mass, and the weight average molecular weight is 200 to It is characterized by containing 20% by mass or less of 400,000 water-soluble polymers.

The layered silicate mineral is preferably smectite-based.
The particle diameter of the layered silicate mineral when dispersed in water is preferably 0.1 μm or less.

The aqueous mold release agent for die casting of the present invention is characterized by blending both a specific layered silicate mineral and an aromatic carboxylate that can be stably and transparently dispersed in water. By blending a specific layered silicate mineral, it is possible to improve the heat retention of the aqueous release agent and at the same time maintain a stable liquid state at all times in the undiluted state and diluted state. As a result, the aqueous mold release agent of the present invention can realize excellent hot water flowability by exhibiting good molten metal heat retention, ie, heat insulation, in the mold release agent film formed by applying it to the mold. . On the other hand, by blending an aromatic carboxylate, high heat resistance is imparted, and seizure can be prevented to prevent deterioration in quality. At the same time, the water-based release agent of the present invention is a stable and easy-to-handle liquid by containing a specific layered silicate mineral and, if necessary, a water-soluble polymer having a weight average molecular weight of 200 to 400,000. This contributes to the improvement of productivity and workability by realizing the state and preventing sedimentation and deposition in the piping. Furthermore, since the aqueous release agent of the present invention can be easily redispersed in water even after drying, it is possible to suppress accumulation of dirt around the machine.
Due to the effects described above, the aqueous mold release agent of the present invention can achieve high product quality and manufacturing efficiency at the same time, and can be suitably used for both high-speed and low-speed die casting.

FIG. 1 is a schematic diagram for explaining the procedure of thermal insulation evaluation. FIG. 2 is a schematic diagram illustrating the procedure for evaluation of releasability.

The aqueous release agent for die casting of the present invention will be described in detail below.
The aqueous mold release agent for die casting of the present invention (hereinafter simply referred to as "aqueous mold release agent") contains a layered silicate mineral, an aromatic carboxylate, and water, and contains 100% by mass of the aqueous mold release agent for die casting. Among them, 0.05 mass %<X≦5 mass % of the layered silicate mineral (X) and 0.005 mass %<Y≦20 mass % of the aromatic carboxylate (Y) are contained.

The aqueous release agent of the present invention contains a layered silicate mineral, which is the main component mineral that constitutes the clay mineral. Clay minerals with a layered structure are negatively charged due to isomorphic substitution of metal ions, and have a large cation exchange capacity. When such a layered clay mineral is dispersed in water, it swells due to changes in surface charge distribution and the like, forming a stable colloidal solution-like dispersion. Moreover, since the layered silicate mineral according to the present invention is composed of fine particles, it is excellent in water dispersibility. In addition, since it is excellent in heat resistance, it hardly generates decomposition gas during die casting. By applying an aqueous mold release agent containing a layered silicate mineral to a mold, it is possible to form a film that is resistant to thermal decomposition, that is, has excellent seizure resistance.

Layered silicate minerals include kaolinite, pyrophyllite, smectite (such as saponite, hectorite, stevensite, beidellite and montmorillonite), vermiculite, mica clay minerals (illite and sericite), talc, glauconite, and Chlorite and the like.

The layered silicate mineral preferably has a particle size of 0.1 μm or less, more specifically 0.05 μm or less when dispersed in water. The finer the particles of the layered silicate mineral in water, the easier it is to disperse, and the more excellent it is in terms of precipitation or prevention of sedimentation, which is suitable for the present invention.

Smectites (saponite, hectorite, stevensite, and beidellite) are preferable as layered silicate minerals that are excellent in water dispersibility, and among smectites, natural or synthetic saponite, hectorite, and stevensite are It is more preferable because it becomes specific fine particles at the time of dilute dispersion using as a medium, and can form a stable dispersion with high transmittance.

For example, when hectorite is added to water, the hectorite enters water as particles so small that they are almost invisible, and the aqueous dispersion exhibits a transparent liquid state. Even if the water dispersion becomes a dry film due to evaporation of water, the water dispersion is dispersed again by pouring water, which is advantageous in terms of preventing nozzle clogging. The aqueous dispersion does not change its state even after two months or more have passed since it was prepared, and no sedimentation or sedimentation is observed. Further, since hectorite is an inorganic powder, it does not thermally decompose even at a temperature of 650 to 720° C., which corresponds to molten metal. Furthermore, since the film formed by the aqueous release agent formed on the entire contact surface between the mold and the molten metal contains hectorite that is difficult to thermally decompose, the film formed by the aqueous release agent covers the entire contact surface between the mold and the molten metal. This is effective in preventing the occurrence of seizure because the die and the molten metal do not come into direct contact with each other.

一般式（１）中、Ｘは水素原子またはカルボキシル基（－ＣＯ₂Ｈ）を表し、Ｘのうち少なくとも１つはカルボキシル基を表す。 An aromatic carboxylic acid salt is a salt of an aromatic carboxylic acid represented by the following general formula (1) and a basic compound such as sodium hydroxide or potassium hydroxide. An anhydride of an aromatic carboxylic acid represented by the following general formula (1) may be used to obtain an aromatic carboxylic acid salt. Aromatic carboxylates have high heat resistance.

In general formula (1), X represents a hydrogen atom or a carboxyl group (--CO ₂ H), and at least one of X represents a carboxyl group.

Specific examples of the aromatic carboxylic acid represented by the following general formula (1) include pyromellitic acid, trimellitic acid and isophthalic acid.
The aromatic carboxylic acid salts used in the present invention are specifically sodium salts or potassium salts of these aromatic carboxylic acids. Specific examples are sodium pyromellitic acid, potassium pyromellitic acid, sodium trimellitic acid, potassium trimellitic acid, sodium isophthalic acid and potassium isophthalic acid. When sodium or potassium, which is an alkali metal, is used as a counterion for the aromatic carboxylic acid, particularly high heat resistance can be imparted to the aqueous release agent.

The aqueous release agent of the present invention uses a combination of a layered silicate mineral and an aromatic carboxylate, so that the release agent film formed on the mold is reduced compared to the case where only the layered silicate mineral is included. uniformity is increased and thermal insulation is improved.

When the total amount of the aqueous release agent is 100% by mass, the concentration of the layered silicate mineral (X) is 0.05% by mass <X ≤ 5% by mass, and the concentration of the aromatic carboxylate (Y) is 0. .005 mass %<Y≦20 mass %. The concentration of the aromatic carboxylate (Y) is preferably 0.1% by mass ≤ Y ≤ 10% by mass.
Incidentally, 100% by mass of the entire aqueous release agent means 100% by mass of the total of the layered silicate mineral, the aromatic carboxylate and the remainder (water and additives).

When the concentrations of the layered silicate mineral and the aromatic carboxylate are within the above ranges, the aqueous release agent of the present invention can be obtained without adding a water-soluble polymer having a weight average molecular weight of 200 to 400,000, which will be described later. In addition to maintaining excellent heat retention, it is possible to maintain a stable liquid state in both the undiluted solution and the diluted solution.

The aromatic carboxylate may be added to the layered silicate mineral at a mass ratio of approximately 3:1. While maintaining the heat resistance, the heat resistance is further improved.
Furthermore, the coexistence of a specific water-soluble polymer improves the fluidity of the water-based mold release agent, ensuring the prevention of nozzle clogging and dirt accumulation without hindering the improvement of heat retention and seizure resistance. can.

In the aqueous release agent, when the concentration of the layered silicate mineral (X) is 5% by mass < X ≤ 25% by mass, in addition to the aromatic carboxylate, a specific water-soluble polymer is an essential component. becomes. At this time, the concentration of the aromatic carboxylate (Y) in 100% by mass of the aqueous release agent for die casting is 0.005% by mass < Y ≤ 20% by mass, and the weight average molecular weight is 200 to 400,000. The concentration of molecules is 20% by mass or less.

Certain water-soluble polymers that exhibit flow improver functionality in aqueous release agents include, for example, polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, and the like.

The weight average molecular weight (Mw) of the water-soluble polymer may be in the range of 200-400,000, preferably in the range of 1,000-100,000, more preferably in the range of 2,000-10,000. In the present invention, it is preferable to use polyethylene glycol or polypropylene glycol having a weight average molecular weight (Mw) of 2,000 to 10,000.

The concentration of the water-soluble polymer having a weight-average molecular weight (Mw) of 200 to 400,000 in the aqueous release agent is the sum of the layered silicate mineral, the aromatic carboxylate, the water-soluble polymer and the remainder of 100% by mass. , preferably 0.001 to 20% by mass, more preferably 0.1 to 10% by mass.

The water-based release agent contains water in addition to the layered silicate mineral, the aromatic carboxylate, and the water-soluble polymer. As water, tap water, distilled water, ion-exchanged water, pure water, or the like is used. Since water is the balance other than the layered silicate mineral, aromatic carboxylate and water-soluble polymer in the aqueous release agent, its concentration is generally 35 to 99% by mass.

In addition to the layered silicate mineral, the water-based release agent of the present invention includes a release component, an emulsifier component, and other ingredients contained in general water-based release agents, within a range that does not impair the effects of the present invention. of additive components may be included.

Release components include silicone compounds, waxes, mineral oils, fats and synthetic oils, and the like. The silicone compound is, for example, silicone oil or the like. The waxes are, for example, petroleum waxes such as paraffin wax, olefin wax, polyethylene wax and polypropylene wax; oxidized waxes such as polyethylene oxide wax and polypropylene oxide; and natural waxes such as beeswax, carnauba wax and montan wax. . The fats and oils are, for example, animal oils and vegetable oils. The synthetic oils are, for example, polybutene and polyester. The release component may be supplied as an emulsion dispersed in water, and these may be used alone or in combination of two or more.

The emulsifier component can emulsify and disperse all the aqueous release agent components contained in the present invention in water. can be used, but nonionic surfactants and anionic surfactants are preferred. Examples of the nonionic surfactant include polyoxyalkylene glycol, polyoxyalkylene alkyl ether, polyoxyalkylene allyl ether and polyoxyethylene sorbitan monooleate. Examples of the anionic surfactant include fatty acid soaps, alkyl/allyl sulfonates, and the like. The emulsifying dispersant component may be used alone or in combination of two or more.

Other additive ingredients are defoamers, corrosion inhibitors, preservatives, rust inhibitors, thickeners and antioxidants.

The method for producing the aqueous release agent of the present invention is not particularly limited. It can be suitably produced by adding a release component and mixing uniformly.

The aqueous mold release agent of the present invention can be used regardless of type, such as squeeze die casting, laminar flow (low speed) die casting, general die casting, and the like.
Materials for die casting are non-ferrous metals such as aluminum, zinc and magnesium and their alloys. Automobile parts using aluminum alloys, for example, can be suitably manufactured by die casting.

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 aqueous release agent]
For Examples 1 to 17 and Comparative Examples 1 to 13, aqueous release agents were prepared according to the compounding ratios shown in Tables 3 and 4.

[Evaluation of aqueous release agent]
(1) Stability The aqueous release agent was allowed to stand at room temperature for 6 months, and then visually evaluated.
A case where turbidity or sediment was not observed was evaluated as ◯, a case where sediment was observed as Δ, and a case where sedimentation or two-layer separation occurred was evaluated as x. The stability of an aqueous mold release agent obtained by diluting a silicone emulsion 5 times with water was used as a standard (◯) for relative evaluation.
In addition, the stability of a 50-fold dilution of the undiluted aqueous release agent was visually evaluated in the same manner as described above. When diluted, it was evaluated after standing for 3 days.

(2) Thermal Insulation The apparatus shown in FIG. 1 was used to evaluate the thermal insulation, that is, heat retention of molten metal. A steel plate with a built-in thermocouple 2 mm below the surface was heated to 300° C. and spray-coated with an aqueous release agent. After that, 100 ml of molten aluminum alloy (ADC12 according to JISK2219) at 680° C. was supplied into the ring placed on the steel plate. At this time, the temperature change indicated by the thermocouple was measured. Table 1 shows the test conditions.

温度上昇が１４０℃未満であった場合を◎、１４０℃以上１５０℃未満の場合を〇、１５０℃以上１７０℃未満の場合を△、１７０℃以上となった場合を×とした。

The case where the temperature rise was less than 140°C was evaluated as ⊚, the case of 140°C or more and less than 150°C was evaluated as ◯, the case of 150°C or more and less than 170°C was evaluated as Δ, and the case of 170°C or more was evaluated as X.

(3) Releasability When the temperature of the mold becomes high, the adhered film is thermally decomposed and disappears, and the adhesion efficiency drops extremely, and the molten metal and the mold come into direct contact, causing seizure. Therefore, a Lub tester test was conducted to confirm whether or not seizure occurred when the temperature of the steel sheet coated with the water-based release agent was raised to 350°C. Table 2 shows the test conditions, and FIG. 2 shows the test method.

A case where no seizure was observed at 350°C was evaluated as ◯, and a case where seizure was observed was evaluated as x. A relative evaluation was made with the releasability of an aqueous release agent obtained by diluting a silicone emulsion 5 times with water as a standard (x).

[Example 1]
0.1 parts by weight of hectorite, 1.5 parts by weight of pyromellitic dianhydride, 0.95 parts by weight of sodium hydroxide, 0.5 parts by weight of silicone emulsion, and water are mixed to make a total of 100 parts by weight of aqueous A release agent was prepared.
The obtained aqueous mold release agent was evaluated for stability, diluent stability, heat insulating property and mold release property, and all of them were ◯.
Table 3 shows the blending amounts of the components of the aqueous release agent and the evaluation results.

[Examples 2 to 17]
Aqueous release agents of Examples 2 to 17 were prepared in the same manner as in Example 1, except that the components shown in Tables 3 and 4 were blended at the compounding ratios shown in Tables 3 and 4, respectively.
In the same manner as in Example 1, the stability of the aqueous release agent, the stability of the diluent, the heat insulating properties and the releasability were evaluated.

Tables 3 and 4 show the evaluation results of the stability of the aqueous release agent, the stability of the diluent, the heat insulating properties, and the releasability.
In Examples 2 and 8, the temperature rise ΔT (°C) was 132.6°C and 141.3°C when the water-based release agent was spray-coated on the steel plate heated to 300°C, and the heat insulation evaluation was ⊚. rice field. In addition, the release resistance during release by the Lub tester test was 9.3 kg when the steel plate temperature was 300 ° C. in Example 2 and 11.8 kg when the steel plate temperature was 350 ° C., and in Example 8 When the steel plate temperature was 300°C, the weight was 10 kg, and when the steel plate temperature was 350°C, the weight was 13 kg.
As shown in Tables 3 and 4, the aqueous release agents of Examples 1 to 17 were excellent in all of stability, diluent stability, heat insulating properties, and release properties.

[Comparative Examples 1 to 13]
Aqueous release agents of Comparative Examples 1 to 13 were prepared in the same manner as in Example 1 except that the components shown in Table 4 were blended at the blending ratios shown in Table 4, and the aqueous release agents were stabilized. properties, diluent stability, thermal insulation and mold releasability were evaluated.
Table 4 shows the evaluation results of the stability of the aqueous release agent, the stability of the diluent, the heat insulating properties, and the releasability.
The water-based release agent of Comparative Example 1 was slightly inferior in heat insulation, indicating that the heat resistance was not sufficient because no aromatic carboxylic acid salt was added. The water-based release agent of Comparative Example 12 also had insufficient heat resistance because the amount of the aromatic carboxylic acid salt was small.
The aqueous release agent of Comparative Example 2 containing no layered silicate mineral was significantly inferior in heat insulating properties. In addition, the film on the mold was uneven, and the releasability was also poor.
The water-based release agent of Comparative Example 3, in which the amount of layered silicate mineral was as small as 0.005% by mass, was inferior in heat insulating properties. The aqueous release agents of Comparative Examples 4 and 5, in which the amount of layered silicate mineral exceeded 5% by mass, were inferior in stability because they did not contain a water-soluble polymer.
The water-based release agent of Comparative Example 6 contained a large amount of layered silicate mineral of 30% by mass, and thus sufficient stability was not obtained even when a water-soluble polymer was added.
The aqueous release agents of Comparative Examples 7 to 9 were slightly inferior in heat insulation, indicating that the heat resistance was not sufficient because no aromatic carboxylic acid salt was added. It was found that the aqueous release agents of Comparative Examples 10 and 11 were inferior in stability, and the polysulfonate and polymaleate did not contribute to stabilizing the dispersion of the layered silicate mineral.
The water-based release agent of Comparative Example 13, in which the amount of the aromatic carboxylic acid salt was as large as 25% by mass, improved the heat insulating properties, but salt precipitation was observed over time.

The components listed in Tables 3 and 4 are as follows.
(1) Hectorite (Smecton SWN; manufactured by Kunimine Industries Co., Ltd.)
(2) Saponite (Sumecton SA; manufactured by Kunimine Industries Co., Ltd.)
(3) Stevensite (Smecton ST; manufactured by Kunimine Industries Co., Ltd.)
(4) Talc (Micro Ace P-4, manufactured by Nippon Talc Co., Ltd.)
(5) Pyromellitic dianhydride (manufactured by Lonza Japan Co., Ltd.)
(6) Trimellitic anhydride (manufactured by Wuxi Momokawa Chemical Co., Ltd.)
(7) Isophthalic acid (manufactured by Lotte Chemical Japan Co., Ltd.)
(8) Polyethylene glycol (PEG10000; manufactured by Sanyo Chemical Industries, Ltd.)
(9) Polyethylene glycol (PEG2000; manufactured by Sanyo Chemical Industries, Ltd.)
(10) polypropylene glycol (Sannics PP-2000; manufactured by Sanyo Chemical Industries, Ltd.)
(11) Silicone emulsion (NR2707; manufactured by Asahi Kasei Wacker Silicone Co., Ltd.))

Claims (5)

Contains a layered silicate mineral, an aromatic carboxylate, and water, and in 100% by mass of the aqueous release agent for die casting,
The layered silicate mineral (X) is 0.05% by mass <X ≤ 5% by mass,
An aqueous release agent for die casting, characterized by containing 0.005% by mass <Y≦20% by mass of an aromatic carboxylate (Y). 2. The aqueous release agent for die casting according to claim 1, further comprising 20% by mass or less of a water-soluble polymer having a weight average molecular weight of 200 to 400,000. A layered silicate mineral, an aromatic carboxylate, a water-soluble polymer with a weight average molecular weight of 200 to 400,000, and water, and in 100% by mass of an aqueous release agent for die casting,
The layered silicate mineral (X) is 5% by mass <X ≤ 25% by mass,
Aromatic carboxylate (Y) is 0.005% by mass < Y ≤ 20% by mass,
An aqueous mold release agent for die casting, characterized by containing 20% by mass or less of a water-soluble polymer having a weight average molecular weight of 200 to 400,000. The aqueous release agent for die casting according to any one of claims 1 to 3, wherein the layered silicate mineral is smectite. 5. The aqueous release agent for die casting according to claim 1, wherein the layered silicate mineral has a particle size of 0.1 μm or less when dispersed in water.

Images