JP2014140848A - Powder release agent for metal mold casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder release agent which can be stably supplied into a cavity of a metal mold, generates only little amount of gas derived from the release agent even when contacting with molten metal such as aluminum, and which keeps excellent releasability and enables the release agent stuck to a casting or the metal mold to be easily washed away by water.SOLUTION: The powder release agent for the metal mold casting applied onto a cavity surface of the metal mold, is composed of (A) water soluble inorganic powder having 5 g/100 g or more of solubility (20°C) to water, (B) ultrafine particle inorganic powder having 0.005 μm - 0.050 μm of an average particle diameter and (C) waxes having 100°C - 180°C of a melting point and 1 μm - 30 μm of an average particle diameter.

Description

  The present invention relates to a powder mold release agent for mold casting, and more particularly to a powder mold release agent applied to a cavity surface of a mold, which improves the cleaning properties from products and molds after casting. It relates to the intended release agent.

  Conventionally, it is known that the die casting method, which is one of the die casting methods, is a production method in which the dimensional accuracy of the obtained product is very high, and the product can be made thinner and lighter. . In addition, in order to prevent the molten metal injected into the cavity from seizing on the cavity surface of the mold used in such a casting method, the product obtained can be easily released from the mold. A predetermined release agent is applied.

  By the way, conventionally used release agents include oily release agents, aqueous release agents (emulsion release agents), and powder release agents. Among them, oil release agents are release agents. Although its properties are good, in addition to the disadvantage that the amount of gas contained in the product increases, it also has the problem of ignition and flammability, and the aqueous mold release agent is applied to the cavity surface when the mold temperature rises. Since it becomes difficult for the release agent to adhere, there are inherent disadvantages of increasing the coating amount and increasing the cooling cycle of the mold and shortening the mold life by applying a large amount of the release agent. . On the other hand, the powder mold release agent can be applied in a short time, and has advantages such as a short casting cycle and an improvement in mold life due to a small cooling cycle. , High initial investment in equipment, easy release agent deposition on areas other than the cavity surface, reduced dimensional stability and burrs, and easy removal of the release agent attached to the casting There are no such things. In particular, problems related to casting workability such as polishing required for removing the mold release agent adhering to the cast and a cleaning step using strong acid or strong alkali are inherent.

  Therefore, in JP-A-9-1282, in such a powder release agent, two or more kinds of waxes having different particle diameters and melting points are mixed in order to improve the dimensional accuracy of the product and suppress the generation of burrs. Powder release agents have been proposed. Moreover, in JP 2001-353550 A and JP 200297481 A, etc., in order to improve the lubricity of the cavity surface of the mold and suppress seizure, it is thermally decomposed by contact with the molten metal, Powder release agents composed of carbonates and hydroxides that generate gas have been proposed. However, in the proposed powder release agents, there is a problem that the release agent adheres to and remains on the product obtained by casting, and the presence of such a release agent on the product surface. There is a problem that the adhesive strength of the adhesive applied to the surface is reduced or the paintability is deteriorated. Therefore, in Japanese Patent Application Laid-Open No. 2005-131673, in order to reduce such poor coating adhesion, a release agent component made of an inorganic amphoteric compound such as aluminum hydroxide or zinc oxide attached to a cast product is alkali degreased. It has been shown that it can be removed in the process.

  As described above, with regard to the powder release agent, not only the improvement of the adhesion of the release agent to the cavity surface of the mold and the improvement of the lubricity, but also the cleaning properties of the release agent attached to the cast product are conventionally known. However, since the countermeasure for such detergency is removal of the mold release agent using alkali, the treatment of the waste liquid discharged from the process is troublesome. In addition to the high processing cost, there is a problem in the safety of work, and it cannot be said that it is practically sufficient.

Japanese Patent Laid-Open No. 9-1282 JP 2001-353550 A Japanese Patent Laid-Open No. 2002-97481 JP 2005-131673 A

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is that a mold release agent is stably supplied into the cavity of the mold, and a molten metal such as aluminum. Powder release that generates little gas derived from the release agent even when touched, maintains excellent release properties, and can easily wash away release agents attached to castings or molds with water It is to provide an agent.

  And in this invention, in order to solve such a subject, it is set as the powder mold release agent apply | coated to the cavity surface of a metal mold | die, (A) Solubility (20 degreeC) with respect to water is 5g / 100g. The above water-soluble inorganic powder, (B) ultrafine inorganic powder having an average particle size of 0.005 μm to 0.050 μm, and (C) melting point: 100 ° C. to 180 ° C., average particle size: 1 μm The gist of the present invention is a powder mold release agent for mold casting, characterized by comprising a wax of ˜30 μm.

  In addition, according to one of the desirable modes of the powder mold release agent for mold casting according to the present invention, the water-soluble inorganic powder has an average particle diameter of 1 μm to 30 μm.

  According to another preferred embodiment of the present invention, at least one of sodium carbonate, sodium bicarbonate, and potassium bicarbonate is used as the water-soluble inorganic powder.

  Furthermore, in another preferable aspect of the present invention, at least one of fumed silica, fumed alumina, and carbon black is used as the ultrafine inorganic powder.

  In addition, according to another desirable aspect of the mold release powder release agent according to the present invention, the total amount of the component (A), the component (B), and the component (C) is 100% by weight. The component (A) is 60 wt% to 79.9 wt%, the component (B) is 0.1 wt% to 10 wt%, and the component (C) is 20 wt% to 30 wt%. Each is used in proportion.

  As described above, in the powder mold release agent for mold casting according to the present invention, the water-soluble inorganic powder (A) having an appropriate solubility in water is used as a base, and the fluidity modification is performed. Basically a three-component system comprising an ultrafine inorganic powder (B), which is a component, and a wax (C) having an appropriate melting point and an average particle size for improving adhesion to a mold. Since it is configured as a powder mixture, in addition to being able to be stably fed into the cavity of the mold, while ensuring excellent mold release properties, The release agent adhering to the mold can be easily removed by a washing operation with water.

  Moreover, such a powder release agent according to the present invention hardly generates gas even when it comes into contact with a molten metal such as an aluminum molten metal poured into a mold, and therefore gas is introduced into a cast product. Problems such as entrainment and casting defects can be advantageously avoided.

It is the photograph which shows the result of having magnified and observed the surface state after washing the mold surface after casting with a microscope (magnification: 100 times), and (a) is the state in which the release agent does not remain or adhere (B) shows a state in which the release agent is slightly attached, and (c) shows a state in which a lot of release agent remains and adheres to the mold surface. It is the graph which shows the measurement precision of a mold release agent obtained in the Example, Comprising: The dispersion | variation in the measurement of a mold release agent at the time of supplying a mold release agent to a metal mold | die is shown. It is a graph which shows the measurement result of the tape peeling load with respect to the casting surface obtained in the Example. It is a graph which shows the result of having measured in the Example the load which acts on the extrusion pin at the time of extruding a cast product from a metal mold | die as extrusion force. It is a graph which shows the result of having measured the gas amount in the casting obtained in the Example.

  By the way, in the powder mold release agent for mold casting according to the present invention described above, the water-soluble inorganic powder as the component (A) can be easily removed by water washing of the mold release agent adhering to the mold or cast product. In order to fully enjoy the effect, it is necessary that the solubility in water is within the range of 5 g / 100 g or more at 20 ° C. And as such (A) component, sodium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate etc. can be mentioned, At least 1 sort (s) of them will be selected and used.

  In addition, when the solubility of the component (A) is lower than 5 g / 100 g, the water washability is deteriorated. Therefore, lithium salts, alkaline earth metal salts, and amphoteric metal salts that dissolve in acids and alkalis have poor solubility in water, and therefore the cleaning properties are deteriorated. Inorganic powders such as potassium and potassium carbonate are not preferred because of high deliquescence. Furthermore, inorganic powders that are neutral when dissolved in water, such as sodium and potassium nitrates and sulfates, have the problem of causing rust in die casting machines. Therefore, in the present invention, an inorganic powder that is alkaline, has low deliquescence, and generates less gas due to decomposition when in contact with a molten metal, such as sodium carbonate, is more preferably used. It becomes.

  In addition, it is generally desirable that the water-soluble inorganic powder as the component (A) has an average particle diameter of 1 μm to 30 μm. If the particle diameter becomes too large, the surface roughness of the cast product will be increased. There is a possibility of adversely affecting the cleaning properties of the release agent. On the other hand, if the particle size becomes too small, it becomes difficult to effectively supply the mold release agent to the mold cavity surface, and it may be difficult to form an effective release agent coating layer. In particular, in the present invention, a fine powder having an average particle diameter of about 5 μm to 15 μm is advantageously used. The fine powder having such a particle size is obtained by pulverizing inorganic particles having a large particle size by a jet mill or the like, or by forming into fine spherical particles by a known method such as spray drying. It can be obtained as a fine powder having a particle size of

  The amount of the water-soluble inorganic powder (A) used is appropriately determined according to the type, particle size, etc., but generally constitutes a powder release agent ( When the total amount of component A), component (B), and component (C) is 100% by weight, 60% to 79.9% by weight, preferably about 65% to 75% by weight is adopted. Become. If the amount of the water-soluble inorganic powder is too small, there is a problem that the detergency deteriorates. If the amount is too large, the amount of other components (B) and (C) is small. This is because there is a risk of causing problems such as poor adhesion and poor supply stability.

  Further, the ultrafine inorganic powder as the component (B) constituting the powder mold release agent for mold casting according to the present invention functions as a fluidity modifier, It is possible to ensure the supply stability of the release agent to the mold. For this reason, such an ultrafine particle inorganic powder has an average particle diameter in the range of 0.005 μm to 0.050 μm, and if the particle diameter is too small, industrial production is difficult. In addition, problems such as difficulty in handling may occur, and if the particle size becomes too large, effective supply stability may not be exhibited. Examples of such ultrafine inorganic powders include fumed silica, fumed alumina, carbon black, and the like, and one or more of them are preferably used. In addition, since the inorganic particles having a particle size of about 10 μm are likely to aggregate, the fluidity is poor, and it is difficult to stably supply the release agent into the mold cavity. In the present invention, by adding ultrafine inorganic powder as a fluidity modifier to the release agent, the fluidity is improved and stable supply is possible. In the present invention, fumed silica or fumed alumina, which can improve the fluidity with a smaller amount of addition, is advantageously used. In order to improve fluidity, the use of metal soap can be considered, but it is not preferable because it can be a gas generating component in a cast product.

  In addition, as the usage-amount of this ultrafine particle inorganic powder (B), when the total amount of (A) component, (B) component, and (C) component which comprises a powder mold release agent is 100 weight%, In general, about 0.1 wt% to 10 wt%, preferably about 0.3 wt% to 5 wt% is advantageously employed. However, if the amount of the ultrafine inorganic powder used is too small, it is difficult to expect a sufficient fluidity-modifying effect, and if it is too large, there is a risk of deteriorating the cleaning properties and lubricity. Because.

  Furthermore, the wax as component (C) constituting the powder mold release agent for mold casting according to the present invention enhances the adhesion of the mold release agent component to the mold cavity surface, and has a melting point of 100. Those having an average particle diameter of 1 to 30 μm are used, and examples thereof include polyethylene wax, polypropylene wax, and amide wax. In general, when die casting is continuously performed, the average temperature of the mold is approximately 200 ° C., and therefore the melting point of such waxes needs to be 200 ° C. or less. When the melting point is lower than 100 ° C., the melt fluidity of the release agent is increased at the high temperature portion of the mold (approximately 350 ° C.), the adhesiveness is lowered, and the release agent adheres. There is a tendency to become difficult. Accordingly, the melting point of the wax is desirably 100 ° C. to 180 ° C., more preferably about 145 ° C. to 160 ° C. Moreover, as the average particle diameter, when the particle diameter is large, the heat transfer property is deteriorated and the melting tends to be difficult. Therefore, the average particle diameter is preferably 1 μm to 30 μm, more preferably 5 μm to 10 μm. .

  As the amount of such waxes used, an amount effective to ensure the adhesion of the release agent to the mold cavity surface is appropriately selected. The component (C) is used in a proportion of 20% to 30% by weight so that the total amount of the component (A), the component (B) and the component (C) constituting the mold is 100% by weight. Will be. If the amount of the component (C) used is too small, it becomes difficult to form an effective release agent film on the mold cavity surface, and there is a problem that the lubricity deteriorates. This is because there arises a problem such as an increase in.

  In addition to the essential three components consisting of the component (A), the component (B) and the component (C) described above, the powder mold release agent for mold casting according to the present invention is not limited to the above. As long as the purpose is not obstructed, a known heat stabilizer, flame retardant, lubricity improver and the like can be added and contained as necessary. In that case, the total addition amount thereof is generally adjusted to be 10% by weight or less, preferably 5% by weight or less.

  Further, the powder mold release agent for die casting according to the present invention is advantageously applied to the die in the die casting method, but is not limited to this, and the low pressure casting method is not limited thereto. It can also be applied as a mold release agent for molds used in high pressure casting, gravity casting, and the like.

  Examples of the present invention will be shown below to clarify the present invention more specifically. However, the present invention is not limited by the description of such examples. Needless to say. In addition to the following examples, the present invention includes various descriptions based on the knowledge of those skilled in the art without departing from the gist of the present invention, in addition to the descriptions in the embodiments of the present invention described above. It should be understood that other changes, modifications, improvements, etc. may be made.

Example 1
Various release agents were prepared by mixing powders of the components (A), (B), and (C) in various proportions shown in Tables 1 and 2 below. In addition, as (A) component, the powder of the various solubility (g / 100g) with respect to the water in 20 degreeC was used. As the general-purpose powder release agent, a commercial product in which talc, wax, graphite and the like are blended was used. Further, the average particle sizes of fumed silica, fumed alumina, and carbon black used as component (B) are 0.007 μm, 0.013 μm, and 0.035 μm, respectively, and are component (C). The polypropylene wax had a melting point of 160 ° C. and an average particle size of 5 μm.

  And about each of these obtained mold release agents, according to the method of the following detergency evaluation 1, the detergency with respect to water was evaluated, respectively, and the result was combined with following Table 1 and Table 2.

-Detergency evaluation 1-
First, after heating a test piece (material: SKD61) to 200 ° C., each release agent is sprayed and applied to the surface to prepare a test piece having a film of the release agent formed on the surface. To do. Next, 60 g of molten aluminum having a molten metal temperature of 700 ° C. was brought into contact with the surface of the test piece on which the release agent film was formed, and then immersed in water at room temperature (immersion time: 2 seconds). The remaining condition of the release agent on the surface of the test piece is magnified and observed with a microscope (magnification: 100 times) to evaluate the cleaning property. As shown in FIG. 1 (a), a case where no release agent residue is observed on the surface of the test piece is marked as ◯, and as shown in FIG. Further, as shown in (c), when a large amount of the release agent residue is observed, it is evaluated as x.

  As is apparent from the results of Tables 1 and 2, among alkali metal salts, sodium salts and potassium salts having good solubility in water show excellent water detergency, whereas water Lithium salts, alkaline earth metal salts, and amphoteric metal salts that are soluble in acids and alkalis have poor water detergency. Further, regarding the blending amount of the wax which is the component (C), it is recognized that when the ratio is increased, the cleaning property is lowered. This is thought to be because when the amount of the wax is increased, the specific gravity difference between the wax and the inorganic powder is large, so that it is difficult to form a uniform film with the inorganic powder.

-Example 2-
Using the release agents 2, 4, 8 and 15 in Example 1, cast tests of molten aluminum using an 800 ton die casting machine were performed. Each mold release agent was sprayed onto the die casting mold in the same manner as in the prior art, and a coating film of a predetermined mold release agent was formed on the cavity surface. And various performance in casting operation using each mold release agent was evaluated as follows, and the result was shown in FIGS.

-Evaluation of supply stability-
In the above-described casting test using the 800-ton die casting machine, the measurement accuracy of each mold release agent with respect to the mold was examined, and the measurement variations of the mold release agents 2, 8 and 15 are shown in FIG.

  As apparent from FIG. 2, it is recognized that the metering accuracy is improved by blending the component (B) which is a fluidity modifier.

-Detergency evaluation 2-
The casting obtained by the above casting test using the 800-ton die casting machine using the release agent 2, 4 or 15 was washed with water consisting of immersing in a 20 ° C. water bath for 3 seconds, and then the smoothness was obtained. Measure the force required for the tape to peel from the casting when a tape with adhesive strength is applied to the surface and pull it in a direction perpendicular to the smooth surface, and remove the release agent from the peeling load. The presence or absence of this was simply evaluated, and the results are shown in FIG.

  As apparent from FIG. 3, in the casting obtained by casting using the mold release agent 2 and the mold release agent 4, there is little residual mold release agent on the surface, and therefore the adhesiveness of the tape is improved. On the other hand, in the case of the release agent 15, it is known that the variation in the tape peeling load is large and the removal of the release agent is not sufficient.

-Lubricity evaluation-
The load acting on the extruding pin when extruding the cast product from the mold in the 800-ton die casting machine was measured as the extruding force, and the lubricity of the release agent was evaluated. The evaluation result about the casting surface obtained by casting using the release agent 2, the release agent 4 or the release agent 15 is shown in FIG.

  As shown in FIG. 4, the extrusion force during casting using the release agent 2 and the release agent 4 is lower than that during casting using the release agent 15, and the lubricity is improved. I can admit that.

-Gas amount evaluation in castings-
The casting obtained by casting with the die casting machine is heated and melted in a vacuum sealed chamber, the amount of gas contained in the casting is calculated from the pressure change in the vacuum chamber, and the gas content in the casting is measured. Evaluation results for the release agent 2, the release agent 4 and the release agent 15 are shown in FIG.

  As is apparent from FIG. 5, the gas content of the casting obtained by casting using the release agent 2 and the release agent 4 is equal to or less than that in the case of using the release agent 15, and It was confirmed that the number of vacancies was not increased.

-Example 3-
About the various mold release agents shown by the following Table 3-Table 5, the performance evaluation was implemented using actual casting equipment. That is, a casting test using an 800-ton die casting machine was performed in the same manner as in Example 2, and the release agent supply stability, detergency, lubricity, and gas amount at that time were evaluated in the same manner as in Example 2. . Regarding the evaluation criteria, as shown in FIG. 2, as for the supply stability, ○ indicating the measurement accuracy such as the release agent 2, × indicating the measurement variation such as the release agent 8, and those Evaluation was made with Δ indicating intermediate measurement accuracy. As for the detergency, as shown in FIG. 3, those indicating a tape peeling load index such as the release agent 2 and the releasing agent 4 are indicated by ○, and those indicating a tape peeling load index such as the release agent 15 are × , And those showing intermediate tape peel load index were evaluated as Δ. Further, regarding the lubricity, as shown in FIG. 4, the one showing an extrusion force index such as the release agent 2 or the release agent 4 is indicated by ○, the one showing an extrusion force index such as the release agent 15 is indicated by ×, and Evaluations were given as Δ indicating those intermediate-stage extrusion force indices. In addition, as shown in FIG. 5, the gas amount was evaluated with a smaller one than the gas amount index of the release agent 15 as “◯” and a larger one as “×”. And the evaluation result of those characteristics was combined with the following Table 3-Table 5, and was shown.

As is apparent from the results of Tables 3 to 5, when die casting is performed using the powder release agents 1 to 7 and 16 to 26 according to the present invention, the release agent 15 is a general-purpose powder release agent. It is recognized that the detergency can be remarkably improved as compared with the detergency. In addition, regarding the lubricity and the amount of gas in the casting, it is recognized that more excellent results can be obtained by optimizing the blending amount and particle size of each component.

Claims (5)

  As a powder release agent applied to the cavity surface of the mold, (A) a water-soluble inorganic powder having a solubility in water (20 ° C.) of 5 g / 100 g or more, and (B) an average particle size of 0 A powder for mold casting, comprising: ultrafine inorganic powder of 0.005 μm to 0.050 μm and (C) waxes having a melting point: 100 ° C. to 180 ° C. and an average particle size of 1 μm to 30 μm Release agent.   The powder mold release agent for mold casting according to claim 1, wherein the water-soluble inorganic powder has an average particle diameter of 1 μm to 30 μm.   The powder mold release agent for mold casting according to claim 1 or 2, wherein at least one of sodium carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate is used as the water-soluble inorganic powder.   The mold casting powder according to any one of claims 1 to 3, wherein at least one of fumed silica, fumed alumina, and carbon black is used as the ultrafine inorganic powder. Release agent. The component (A) is 60% by weight to 79.9% by weight so that the total amount of the component (A), the component (B) and the component (C) is 100% by weight. The gold according to any one of claims 1 to 4, wherein the component is used in a proportion of 0.1 wt% to 10 wt% and the component (C) is used in a proportion of 20 wt% to 30 wt%, respectively. Powder release agent for mold casting.