JPH09176675A - Working oil for aluminum material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a working oil for aluminum materials, capable of advanced working of aluminum materials and thermal degreasing under atmospheric pressure. SOLUTION: An aluminum material is worked with a working oil comprising a base oil comprising a hydrocarbon having a maximum molecular weight of 282-378 and 3wt.% or above additive comprising an alcohol or a carboxylic acid having a maximum molecular weight of 378 or below. By setting the maximum molecular weights of the base oil and the additive at 378 or below, the material can be easily thermally degreased under atmospheric temperature because of their low temperatures of perfect evaporation. Further, since the maximum molecular weight of the base oil is 282 or above and has an evaporation rate sufficiently low at ordinary temperature, the disconnection of an oil film seldom occurs when the equipment is stopped. Because the working oil contains 3wt.% or above additive comprising an alcohol or a carboxylic acid, it can give workability at least equivalent to that of a conventional working oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing oil used for pressing aluminum materials.

[0002]

2. Description of the Related Art It is known that processing oil is used to improve slidability between a mold material and a material to be processed when press working. Conventionally, in the press working of steel materials,
Highly viscous processing oil is used when processing with a high degree of processing. Here, the "working degree" refers to the degree of deformation of the work piece due to press working. In addition, "processing with a high degree of processing" refers to processing with severe processing conditions, such as press processing with a small diameter and a deep drawing depth. Oils improving agents such as organic acids and esters having a relatively large molecular weight and extreme pressure agents such as chlorinated fatty acids are often added to the processing oil for steel products. As such processing oil, for example,
There is a base oil belonging to the third petroleum, to which fats and oils having a molecular weight of about 880 are added. Even when the material to be processed is an aluminum material, this conventional processing oil for steel materials is often used.

After pressing, in order to guarantee the quality in the subsequent steps such as brazing, painting, welding and surface treatment, the work material is subjected to a degreasing step for removing the working oil. In this degreasing process, it is necessary to remove both the base oil and the high-molecular-weight fats and oils, so the method of removing the processing oil by water-soluble washing, the method of evaporating and removing the processing oil by heating the workpiece, etc. Done.

[0004]

FIG. 6 shows a case where degreasing is performed by the above method in press working of aluminum material.
This will be described with reference to FIG. After assembling the unit 3 including the parts 1 and 2 formed by pressing an aluminum material, the unit 3 is washed with water to degrease the working oil attached during the pressing. In this water-soluble washing step, the unit 3 is first washed with hot water in the water bath 11. Then, the plurality of compartments 121, 122, 12
In the alkaline bath 12 having 3, 124, the unit 3 is sequentially moved from the compartment 121 located at the left end in FIG. 6 to the compartment 124 side located at the right end. When the unit 3 is moved from the water bath 11 to the compartment 121 and when the unit 3 is pulled up from the compartments 121, 122, 123, 124, the unit 3 is blown to the unit 3 by the air blow 14 in order to reduce the carry-in of the adhered liquid to the next tank. Blow air to remove adhering liquid. The alkaline bath 12 filled with the alkaline cleaning liquid is replenished with a degreasing agent from the compartment 124 side, and the cleaning liquid overflowing from the compartment 124 is provided in the adjacent compartment 12.
The cleaning liquid flowing into the chamber 3 and overflowing from the compartment 123 flows into the adjacent compartment 122. The cleaning liquid contaminated with oil is discharged from the compartment 121 to the wastewater treatment plant 15. Then, the unit 3 is gradually degreased while moving from the compartment 121 to the compartment 124 side. After that, the compartments 131, 132, 1
In the water bath 13 having 33 and supplied with the washing water from the side of the compartment 131, the washing liquid adhered in the alkaline bath 12 is washed off from the unit 3. Finally, the unit 3 is heated and dried in the drying furnace 16 to complete the degreasing process. After the degreasing process, the core 3 is assembled from the unit 3 and brazed.

However, according to the water-soluble cleaning performed by this method, the water bath 11 and the alkaline bath 12
Also, a large amount of waste liquid is generated from the water bath 13, which is not preferable in terms of environmental protection, and there is a problem that the installation cost of the wastewater treatment facility and the wastewater treatment cost are relatively expensive. Further, according to the above method, since the high molecular weight component in the processing oil is hard to evaporate, a heating facility in vacuum is required, or the processing oil is washed and replaced with a light oil that easily evaporates and heated. Is required. Therefore, the equipment cost and the raw material cost are increased.

On the other hand, if the degree of processing is not so high, it is possible to use a low-viscosity processing oil. In this case, a method of heating and degreasing the processing oil without replacement with a light oil, or natural processing oil is used. Examples of the degreasing method include a method of evaporating the processing oil by drying. The above method can be carried out under atmospheric pressure if the boiling points of the base oil and the additives contained in the processing oil are sufficiently low. Further, the above method has an advantage that heating is unnecessary. Comparing the above methods (1) to (4), the total cost including equipment cost and energy becomes cheaper in the order of >>>>.

However, the low-viscosity processing oil used in the above and the above methods has the property of being highly vaporizable at room temperature. Therefore, according to the low-viscosity processing oil that has been conventionally used, when the equipment is stopped for 2-3 days on a holiday or the like, the processing oil may evaporate and the oil film of the sliding part such as the mold material may be broken. . As a result, the coefficient of friction between the mold material and the material to be processed increases, which may cause damage to the equipment sliding parts and the mold material while the mold material is repeatedly used. Further, there is a problem that rust is generated on the mold material due to the evaporation of the processing oil, and even the oil content necessary for the equipment is removed by the processing oil.

An object of the present invention is to provide a processing oil for an aluminum material, which is capable of performing processing with a high degree of processing on an aluminum material and which can be degreased by heating under atmospheric pressure. Another object of the present invention is to provide a processing oil of an aluminum material which is inexpensive and can be removed by a degreasing method which has little influence on the natural environment.

[0009]

In order to solve the above-mentioned problems, it is desirable that the processing oil of the aluminum material of the present invention satisfies the following characteristics. (1) Being a third petroleum product. This is because, since many conventional processed oils belong to the third petroleum group, the processed oil of the present invention can be conveniently managed if it belongs to the third petroleum group. .

(2) The complete evaporation temperature is not less than room temperature and not more than 200 ° C. The atmospheric degreasing is carried out at a temperature below the ignition point of the processing oil. The ignition point of the flammable liquid belonging to the third petroleum is 20.
Since it is about 0 ° C to 300 ° C, the complete evaporation temperature of the processing oil of the present invention is preferably 200 ° C or lower. Also,
In order to save energy and shorten the degreasing time, it is preferable that the complete evaporation temperature is as low as possible in the temperature range of room temperature or higher. In the present specification, the “complete evaporation temperature” refers to the temperature at which the residual weight becomes 0 by increasing the temperature from room temperature at a rate of 10 ° C./min by differential thermal analysis using 10 mg of the sample. At this time, it can be considered that the processing oil has been removed to the extent that it does not affect the processes such as brazing, painting, welding, and surface treatment that are performed after pressing.
This "complete evaporation temperature" is used as a standard for the lower limit of the heating temperature at which degreasing can be performed at atmospheric pressure.

(3) The workability is equal to or higher than that of conventional processing oil. (4) The oil film is maintained after being left at room temperature for 72 hours. This is to prevent the oil film covering the surface of the mold material or the like from being broken when the facility is stopped on a holiday. For example, when the equipment is stopped from 5 pm on Friday to 8 am on the following Monday, the equipment stop time is 64 hours. It is preferable that a good oil film is maintained even after 72 hours after adding the allowance (8 hours) until the oil film runs out to the 64 hours.

In consideration of the above conditions (1) to (4), the processing oil for an aluminum material according to claim 1 of the present invention has a maximum molecular weight of 28.
It is characterized by comprising a base oil composed of a hydrocarbon of 2 or more and 378 or less and 3% by weight or more of an additive composed of an alcohol or a carboxylic acid having a maximum molecular weight of 378 or less.

Here, the maximum molecular weights of the base oil and the additive are set to 378 or less because the maximum molecular weights of these are 37 or less.
If it exceeds 8, the complete evaporation temperature becomes excessively high, and the total energy cost required for degreasing and the degreasing time increase. Further, if the maximum molecular weight of the base oil is less than 282, the evaporation rate at room temperature will be excessively high and the oil film will be easily broken when the equipment is stopped.
2 or more. Further, the reason for adding 3% by weight or more of an alcohol or a carboxylic acid as an additive is to obtain a processability equal to or higher than that of a conventional processing oil. Here, the "workability" represents the property of the working oil that determines the working degree at which press working is possible. By using the processing oil having a better workability, it is possible to perform press working with a higher workability on the work material. Although the workability is improved as the amount of the additive is increased, the amount of the additive is preferably 20% by weight or less because the alcohol and the carboxylic acid are generally expensive as compared with the hydrocarbon. More preferably.

Further, when the aluminum material is not so highly processed, it may be desirable to use a processing oil that emphasizes degreasing property rather than processability. The processing oil of the aluminum material according to claim 2 is a processing oil suitable for such a case, and has a maximum molecular weight of 2
Base oil consisting of hydrocarbons less than 82 and maximum molecular weight 2
It is characterized in that it comprises 3% by weight or more of an additive of 82 or more and 378 or less alcohol or carboxylic acid.

According to the processing oil of the aluminum material of claim 2, the maximum molecular weight of the base oil is less than 282, so that the complete evaporation temperature of the processing oil is lower than that of the processing oil of claim 1, so that degreasing is performed. The property is improved. By setting the maximum molecular weight of the alcohol or carboxylic acid as an additive to 282 or more, the additive remains even after the base oil having a small maximum molecular weight evaporates, so that it is effective in preventing the oil film from running out when the equipment is stopped. The maximum molecular weight of this additive is 3
Since it is 78 or less, it can be easily removed by atmospheric degreasing. Although the processability is improved as the content of alcohol or carboxylic acid is increased, the complete evaporation temperature of the processing oil tends to be high, and generally, alcohol and carboxylic acid are expensive as compared with hydrocarbons,
The additive amount is preferably 20% by weight or less, and 10
It is more preferable that the content is not more than wt%.

Further, the processing oil of the aluminum material according to claim 3 is a processing oil in which degreasing property is further emphasized, and a base oil composed of a hydrocarbon having a maximum molecular weight of less than 282 and an alcohol having a maximum molecular weight of less than 282 or 3% by weight or more of the first additive consisting of a carboxylic acid, and a maximum molecular weight of 282 or more 378
It is characterized in that it comprises 0.25% by weight or more of a second additive consisting of the following ester.

According to the processing oil of aluminum material of claim 4, since the maximum molecular weights of the base oil and the first additive are both less than 282, the complete evaporation temperature of the processing oil is low and the degreasing property is good. Also, as the second additive, the maximum molecular weight is 28
By containing 0.25% by weight or more of the ester of 2 or more and 378 or less, the second additive remains even after the base oil having a small maximum molecular weight is evaporated, so that there is an effect of preventing oil film breakage at the time of facility shutdown. . Since the maximum molecular weight of this second additive is 378 or less, it can be easily removed by atmospheric degreasing. The effect of preventing oil film breakage increases as the ester content increases, while the complete evaporation temperature of the processing oil tends to increase, and since esters are generally more expensive than hydrocarbons,
The ester content is preferably 10% by weight or less, more preferably 5% by weight or less. Also,
Although the workability improves as the amount of the first additive increases,
Generally, alcohols and carboxylic acids are more expensive than hydrocarbons, so the amount of the first additive is preferably 20% by weight or less, and more preferably 10% by weight or less.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. First, selection of the processing oil of the present invention will be described. [1] Relationship between Maximum Molecular Weight M and Complete Evaporation Temperature T The complete evaporation temperature T of the hydrocarbon-based processing oil samples A to F shown in Table 1 was measured. The measurement was performed by differential thermal analysis using a 10 mg sample, and the temperature at which the residual weight became 0 when the temperature was raised from room temperature to 10 ° C./min was defined as the complete evaporation temperature T. Regarding these samples A to F, a plurality of samples each consisting of a hydrocarbon as a base oil and 20% by weight or less of an additive selected from various fats and oils having a maximum molecular weight M of 183 to 880, fatty acids, esters and alcohols are used. It was produced and the complete evaporation temperature T was measured.

[0019]

[Table 1]

From the above measurement results, FIG. 1 shows a characteristic diagram in which the relationship between the maximum molecular weight M of the substance contained in each sample and the complete evaporation temperature T is plotted. Then, the regression equation (a) shown below was obtained from this characteristic. T = 0.36M + 63.851 (a) From this regression equation (a), a hydrocarbon having a maximum molecular weight M of 378 or less is used as a base oil, and the maximum molecular weight M is 3
If the processing oil contains additives selected from fats and oils of 78 or less, fatty acids, esters and alcohols, the complete evaporation temperature T will be 200 ° C or lower. Therefore, atmospheric degreasing can be performed at 200 ° C. or lower. Further, the conventional processing oil obtained by adding a fat or oil having a molecular weight of about 880 to the base oil belonging to the third petroleum as an additive reaches a complete evaporation temperature T of 400 ° C., and therefore, it cannot be degreased by heating in the atmosphere at 200 ° C. or lower. It can be seen from FIG.

[2] Examination of processability Mineral oil and synthetic hydrocarbons are used as the base oil of the process oil, but since the composition of this base oil alone has no polar group, the adsorptivity to the surface of the aluminum material is low. Insufficient workability can not be obtained due to lack. In order to improve the processability, it is effective to add an additive composed of a compound having a polar group such as a carboxyl group, a hydroxyl group and an ester group. As such additives, conventional processing oils for steel materials use oils and fats, fatty acids, esters, alcohols and the like, and the effect of improving the workability is said to increase in the order of alcohol <ester <fatty acid <oil and fat.

Of the above, fats and oils having a large molecular weight were excluded, and fatty acids, esters, and alcohols having a maximum molecular weight M of 378 or less were examined for the effect of improving processability. The base oil has an average molecular weight of 183 (maximum molecular weight M of 21
The paraffin hydrocarbon of 2) was used. The workability improving effect was evaluated by a cylindrical deep drawing test. That is,
An aluminum disc was prepared as a work material, and a cylindrical deep drawing process was performed on the aluminum disc with a punch. The "drawing ratio" was calculated by dividing the "largest aluminum disk diameter D that can be drawn" by the "punch diameter d". It is shown that the higher the drawing ratio, the higher the workability of the aluminum disc, and the better the workability.

FIG. 2 shows the relationship between the type and amount of additive and the reduction ratio. In addition, in FIG. 2, "conventional oil level"
Indicates a drawing ratio obtained by similarly performing cylindrical deep drawing of an aluminum disc using a conventional processing oil for steel materials in which a fat and oil having a maximum molecular weight M of 880 is added to mineral oil. It can be seen from FIG. 2 that by adding 3% by weight or more of an additive consisting of a fatty acid or an alcohol to the base oil, the processability higher than the conventional oil level can be obtained.

Although carboxylic acids other than fatty acids may be used as the additive, fatty acids, particularly linear monocarboxylic acids, are preferably used for closely adsorbing polar groups on the surface of the aluminum material. preferable. Furthermore, in order to prevent corrosion of the mold material and reduce the cost of raw materials, it is preferable to use alcohol, particularly chain alcohol, rather than carboxylic acid.
Further, a mixture of alcohol and carboxylic acid may be used as an additive.

[3] Examination of Evaporation Rate V The aluminum plate material was immersed in various hydrocarbons having different maximum molecular weights M and then taken out, and the evaporation rate V was obtained from the weight reduction rate. FIG. 3 is a characteristic diagram in which the relationship between the maximum molecular weight M and the evaporation rate V is plotted.
Shown in Then, the regression equation (b) shown below was obtained from this characteristic.

V = −0.00076M + 0.33 (b) In press working of aluminum material, the amount of working oil adhered to equipment parts is about 500 to 2000 mg / dm ² . Further, if some of the processing oil attached to the equipment remains 72 hours after the equipment is stopped, it is considered possible to prevent the oil film from running out when the equipment is stopped on a holiday. According to the following formula (c), 72 hours,
That is, the evaporation rate V at which the minimum amount of deposited processing oil of 500 mg / dm ² was evaporated in less than 4320 minutes was determined.

500 [mg / dm ² ] / 4320 [min] = 0.115 [mg / (dm ² min)] (c) As shown in FIG. 3, when the maximum molecular weight M is 282 or more The evaporation rate V becomes 0.115 mg / dm ² min or less. Therefore, it is understood that if the maximum molecular weight M is 282 or more, even if the minimum adhesion amount is 500 mg / dm ² , a part of the processing oil remains even after 72 hours, so that the oil film breakage can be prevented.

From the results of the examinations [1] to [3] above, it was determined that the base oil consisting of a hydrocarbon having a maximum molecular weight M of 378 or less and the additive consisting of an alcohol or a carboxylic acid having a maximum molecular weight M of 378 or less should be 3% by weight or more. If the maximum molecular weight of either the base oil or the additive is 282 or more, it is possible to prevent the oil film from running out when the equipment is stopped, and to degrease it by heating to the atmosphere. It can be seen that it has some workability.

[4] Study on Improving Degreasing Property When the degree of processing of the aluminum material is not so high, it may be desirable to use a processing oil that emphasizes degreasing property rather than processability.
For example, when the shape of the parts is relatively complicated, or when degreasing is performed after core assembly, which is a post-process shown in FIG. 6, it is difficult to degrease every corner of the parts. Degreasing is required. Further, from the viewpoint of reducing the heating cost and shortening the heating time, it is preferable that the degreasing property is high as long as the workability required for the application can be obtained and the oil film can be prevented from running out when the equipment is stopped.

One of the means for improving the degreasing property is to use a hydrocarbon having a maximum molecular weight M of less than 282 as a base oil which occupies most of the processing oil in order to lower the complete evaporation temperature T.
This is to add an alcohol or a carboxylic acid having a maximum molecular weight M of 282 or more, which has a sufficiently low evaporation rate V at room temperature in order to prevent oil film breakage. Also, the complete evaporation temperature T
Of 200 ° C. or less, the maximum molecular weight M of this alcohol or carboxylic acid is 378 or less. As the carboxylic acid having a maximum molecular weight M of 282 or more and 378 or less that can be used in such a composition, for example, stearic acid (molecular weight 2
84).

In order to further improve the degreasing property, a hydrocarbon having a maximum molecular weight M of less than 282 as a base oil,
A combination with an alcohol or a carboxylic acid having a maximum molecular weight M of 282 or less as a first additive is considered. However, according to this composition, since the evaporation rate V of the base oil and the first additive is both high, there is a problem that oil film breakage easily occurs when the equipment is stopped.

As shown in FIG. 4, the maximum molecular weight M of mineral oil is
Of 880 is added to the conventional processing oil for steel materials (conventional example), and a processing oil obtained by adding 5% by weight of an alcohol having a maximum molecular weight M of 282 or less to a paraffinic hydrocarbon having a maximum molecular weight M of 212 (Comparative Example 1). ), The oil film breakage was compared. The evaluation of the occurrence of oil film breakage was carried out by applying the working oil of the conventional example and the comparative example 1 to the test piece and measuring the maximum friction coefficient immediately after application, 24 hours and 72 hours later by the Bowden test method. In the conventional example, the friction coefficient was as low as about 0.2 even after 72 hours, but in Comparative Example 1, the friction coefficient increased to about 0.5 after 24 hours. From this, it can be seen that in Comparative Example 1, the oil film was cut off in a time of 24 hours or less.

Therefore, a processing oil obtained by adding 0.25% by weight of an ester having a maximum molecular weight M of 299 to the composition of Comparative Example 1 (Example 1) and a processing oil obtained by adding 0.5% by weight of the same ester (Example 2) ) And the processing oil added with 1.0% by weight of the same ester (Example 3), the change in the friction coefficient with time was observed in the same manner, and the friction coefficient after 24 hours, which is the highest friction coefficient of the conventional example, was 0.2. Compared to 25. As a result, as shown in FIG. 5, it was found that the friction coefficient was kept at 0.25 or less even after 72 hours by adding 0.25% by weight or more of the ester having the maximum molecular weight M299. It is considered that this is because the maximum molecular weight M of the ester is 299, which is larger than 282 which is the maximum molecular weight M that completely evaporates after 72 hours at room temperature. Therefore, by adding an ester having a maximum molecular weight M of 282 or more and 378 or less in an amount of 1% by weight or more, a processing oil having good degreasing properties and capable of preventing oil film breakage can be obtained. Since the degreasing property decreases as the amount of ester added increases, the amount of ester added is preferably 10% by weight or more, and more preferably 5% by weight or less.

Alcohols having a maximum molecular weight M of less than 282 include lauryl alcohol (molecular weight 186),
Isotridecyl alcohol (molecular weight 200), cetyl alcohol (molecular weight 242) and mixtures thereof can be used. Examples of alcohols having a maximum molecular weight M of less than 282 include lauric acid (molecular weight 200)
Can be used. Further, as the ester having a molecular weight of 282 or more and 378 or less, oleic acid monoglyceride (molecular weight 344), oleic acid glycerin (molecular weight 330), dibutyl sebacate (molecular weight 314), a mixture thereof and the like can be used.

From the results of the above [1] to [4], Table 2 shows the composition that can be used as the processing oil of the present invention. The numbers in Table 2 indicate the maximum molecular weight M of each substance.

[0036]

[Table 2]

Composition 1 is a processing oil that places the highest importance on processability, and compositions 2 and 3 are processing oils that place a higher importance on degreasing properties. If a high degreasing property is not required as long as it can be degreased by heating in the air, it is advantageous to use the processing oil having the composition 1 in order to reduce the raw material cost. This is because, as the base oil composed of a hydrocarbon having a maximum molecular weight M of 282 or more and 378 or less, a mineral oil that is generally cheaper than the synthetic hydrocarbon can be used instead of the synthetic hydrocarbon.

In the conventional working oil for steel materials, a high-viscosity working oil was used when performing press working with a high working degree. In such a processing oil, a hydrocarbon having a high average molecular weight is generally used as a high-viscosity base oil.
Unlike the processing oil for steel materials, the present inventor has found that even if a low-viscosity base oil having an average molecular weight of about 183 is used as the processing oil for aluminum materials, the conventional addition of alcohol by 3% by weight or more It was found that the same processability as that of the high-viscosity processing oil can be obtained. Therefore, the base oil may be selected based on the maximum molecular weight M related to the complete evaporation temperature T without being restricted by the average molecular weight.

In addition to the materials shown in Table 2, materials having a complete evaporation temperature of 200 ° C. or lower can be added to the processing oil of the present invention. Next, a method for degreasing the processing oil of the present invention obtained by the above-mentioned examination will be described. FIG. 5 shows an example of an atmospheric heating degreasing step performed after pressing an aluminum material using the processing oil of the present invention shown in Table 2.

In the evaporation chamber 20 at atmospheric pressure, the press-processed aluminum material 21 to be degreased is heated to 200
Heat to a temperature below ° C to evaporate the processing oil. The evaporated processing oil is burned by the afterburner 22 and discharged to the outside. Part of the heat generated by the combustion of the processing oil is reused for controlling the temperature of the evaporation chamber 20. Further, the evaporated processing oil may be recovered and reused.

According to the atmospheric heating degreasing process shown in FIG. 5, since the degreasing process is performed under atmospheric pressure, vacuum heating equipment is not required, so that the total cost for degreasing can be reduced. Further, by using a base oil or an additive having an evaporation rate at room temperature which is equal to or lower than a predetermined value, it is possible to prevent the oil film from being broken when the equipment is stopped. Further, unlike the conventional water-soluble cleaning, there is an advantage that there is little influence on the environment because no waste liquid is generated.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing a relationship between a maximum molecular weight M and a complete evaporation temperature T.

FIG. 2 is a characteristic diagram showing a relationship between an additive concentration and processability.

FIG. 3 is a characteristic diagram showing the relationship between the maximum molecular weight M and the evaporation rate V.

FIG. 4 is a characteristic diagram showing a relationship between an additive concentration and a change with time of a friction coefficient.

FIG. 5 is a schematic view showing an example of an atmospheric heating degreasing process using the processed oil of the present invention.

FIG. 6 is a schematic diagram showing a conventional degreasing process.

[Explanation of symbols]

 20 evaporation chamber 21 degreased material 22 afterburner

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Haruhiko Matsushita 1-1, Showa-cho, Kariya city, Aichi prefecture

Claims (5)

[Claims] 1. A processing oil for an aluminum material, comprising a base oil composed of a hydrocarbon having a maximum molecular weight of 282 or more and 378 or less and 3% by weight or more of an additive composed of an alcohol or a carboxylic acid having a maximum molecular weight of 378 or less. . 2. A processing oil for an aluminum material comprising a base oil composed of a hydrocarbon having a maximum molecular weight of less than 282 and 3% by weight or more of an additive composed of an alcohol or a carboxylic acid having a maximum molecular weight of 282 to 378. . 3. The processing oil for aluminum material according to claim 1, wherein the content of the additive is 3 to 20% by weight. 4. A base oil comprising a hydrocarbon having a maximum molecular weight of less than 282, 3% by weight or more of a first additive comprising an alcohol or a carboxylic acid having a maximum molecular weight of less than 282, and an ester having a maximum molecular weight of 282 or more and 378 or less. 2. Processing oil for aluminum material, characterized by comprising 0.25% by weight or more of additive. 5. The content of the first additive is 3 to 20% by weight, and the content of the second additive is 0.25 to 10% by weight. Processing oil for aluminum materials.