JP2014028894A - Lubricant composition for metal powder metallurgy and method for producing said composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricant composition for metal powder metallurgy, which is a cold internal lubricant added to metal powder and enables a molded part to be easily released from a metal mold even at high pressure in molding by metallurgy.SOLUTION: The lubricant composition for metal powder metallurgy contains: a fatty acid amide represented by the following general formula (1), where Rrepresents a C15-C19 alkyl group or alkenyl group); an N,N'-alkylene bis fatty acid amide represented by the following general formula (2), where Rand Reach represent a C15-C19 alkyl group or alkenyl group and Rrepresents a C1-C6 alkylene group; and a fatty acid glyceride.

Description

  TECHNICAL FIELD The present invention relates to a lubricant composition for metal powder metallurgy having high lubricity that can easily extract a molded product from a mold even when the metal powder is compressed with a high compressive force in a metallurgical process for compression molding metal powder.

  In metallurgy, in which metal powder is put into a mold and a part is obtained by compression molding with a press machine, a lubricant such as metal soap or fatty acid amide is used to smoothly remove the part from the mold. These lubricants are usually cold-added type lubricants that are uniformly mixed with metal powder and then compression-molded at a pressure of about 700 MPa. Will cause problems that cannot be removed smoothly. However, the market demands high-density parts, and there has been a demand for continuous compression molding at a high pressure of about 800 MPa.

  When compression is formed at a high pressure, there arises a problem that the parts cannot be removed smoothly from the mold. Therefore, it is necessary to improve lubricity so that components can be removed smoothly from the mold. As such a method, a method of directly applying a lubricant to a mold is known (see, for example, Patent Documents 1 to 3). However, the method of directly applying the lubricant to the mold is economically preferable because the mold and the metal powder must be heated and molded, and thus there is a cost such as utility costs, and the application time and heating time are also required. Absent. Furthermore, since a dedicated facility for applying the lubricant is also required, a lubricity that can cope with a high pressure with a cold internal type lubricant has been demanded.

  Patent Document 4 discloses a metastable lubricating composite obtained by mixing two types of lubricants having different melting points at high temperatures and rapidly cooling them. However, such two types of lubricants are not sufficient as a lubricant.

JP 2000-144206 A JP 2000-199002 A JP 2005-256073 A Japanese Patent No. 4758045

  Accordingly, the problem to be solved by the present invention is a cold internal type lubricant added to metal powder, which can be easily taken out from the mold even at high pressure in metallurgical molding. The object is to provide a lubricant composition for powder metallurgy and a method for producing the composition.

  Thus, the present inventors diligently studied and found an internally added type lubricant composition for metal powder metallurgy having good lubricity even under high pressure, and led to the present invention. That is, the present invention includes a fatty acid amide (A) represented by the following general formula (1), an N, N′-alkylenebis fatty acid amide (B) represented by the following general formula (2), and the following general formula: It is a lubricant composition for metal powder metallurgy characterized by containing the fatty acid glyceride (C) represented by Formula (3).

(In the formula, R ¹ represents an alkyl group or an alkenyl group having 15 to 19 carbon atoms.)

(In the formula, R ² and R ³ each represent an alkyl group or an alkenyl group having 15 to 19 carbon atoms, and R ⁴ represents an alkylene group having 1 to 6 carbon atoms.)

(In the formula, R ^{5 to} R ⁷ each independently represent a hydrogen atom or a group represented by the general formula (4). However, any one or more of R ^{5 to} R ⁷ are represented by the general formula (4). It must be a group represented by

Wherein R ⁸ is selected from the group consisting of an alkyl group having 11 to 23 carbon atoms, an alkenyl group having 11 to 23 carbon atoms, a hydroxyalkyl group having 11 to 23 carbon atoms, and a hydroxyalkenyl group having 11 to 23 carbon atoms. Represents any group.)

  Furthermore, this invention heats the mixture containing said fatty acid amide (A), N, N'-alkylenebis fatty acid amide (B), and fatty acid glyceride (C) more than the temperature (melting | fusing point) at which this mixture melts. There is also provided a method for producing a lubricant composition for metal powder metallurgy, which comprises a step of spraying the liquid into a liquid form.

  The effect of the present invention is a cold-added type lubricant to be added to metal powder, and in metallurgy molding, a metal powder metallurgical lubricant composition that allows a molded part to be easily taken out from a mold even at high pressure. It is in providing the thing.

6 is a diagram showing the results of X-ray crystal structure analysis of Example 7. FIG. It is a figure which shows the result of the X-ray crystal structure analysis of Example 13. It is a figure which shows the result of the differential scanning calorimetry of Example 7. It is a figure which shows the result of the differential scanning calorimetry of Example 13.

  The fatty acid amide (A) which is one component of the lubricant composition for metal powder metallurgy of the present invention is represented by the following general formula (1).

(In the formula, R ¹ represents an alkyl group or an alkenyl group having 15 to 19 carbon atoms.)

R ^{1 in the} general formula (1) represents an alkyl group or an alkenyl group having 15 to 19 carbon atoms. Examples of such groups include pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, isopentadecyl group, isohexadecyl group, isoheptadecyl group, isooctadecyl group, isononadecyl group and other alkyl groups; pentadecenyl group, hexadecenyl group Alkenyl groups such as a group, a heptadecenyl group, an octadecenyl group, a nonadecenyl group, an isopentadecenyl group, an isohexadecenyl group, an isoheptadecenyl group, an isooctadecenyl group, and an isononadecenyl group. Of these, alkyl groups are preferred because of their high lubricity. Examples of the fatty acid amide (A) that is generally available include palmitic acid amide, stearic acid amide, and oleic acid amide.

  N, N′-alkylenebisfatty acid amide (B), which is one component of the lubricant composition for metal powder metallurgy of the present invention, is represented by the following general formula (2).

(In the formula, R ² and R ³ each represent an alkyl group or an alkenyl group having 15 to 19 carbon atoms, and R ⁴ represents an alkylene group having 2 to 6 carbon atoms.)

R ² and R ^{3 in} the general formula (2) represent an alkyl group or an alkenyl group having 15 to 19 carbon atoms. Examples of such groups include pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, isopentadecyl group, isohexadecyl group, isoheptadecyl group, isooctadecyl group, isononadecyl group and other alkyl groups; pentadecenyl group, hexadecenyl group Alkenyl groups such as a group, a heptadecenyl group, an octadecenyl group, a nonadecenyl group, an isopentadecenyl group, an isohexadecenyl group, an isoheptadecenyl group, an isooctadecenyl group, and an isononadecenyl group. Of these, alkyl groups are preferred because of their high lubricity. R ² and R ³ may be the same or different, but are preferably the same. As a production method, for example, ethylenediamine and oleic acid, stearic acid, or a mixture of these fatty acids may be amidated by an existing method.

R ^{4 in the} general formula (2) represents an alkylene group of 1 to 6. Examples of such groups include a methylene group, an ethylene group, a propylene group, a butylene group, a tertiary butylene group, a pentylene group, and a hexylene group. Among these, R ⁴ is preferably an ethylene group because the raw material conditions are good and it can be obtained at low cost.

  The fatty acid glyceride (C) which is one component of the lubricant composition for metal powder metallurgy of the present invention is represented by the following general formula (3).

(In the formula, R ^{5 to} R ⁷ each independently represent a hydrogen atom or a group represented by the general formula (4). However, any one or more of R ^{5 to} R ⁷ are represented by the general formula (4). It must be a group represented by

Wherein R ⁸ is selected from the group consisting of an alkyl group having 11 to 23 carbon atoms, an alkenyl group having 11 to 23 carbon atoms, a hydroxyalkyl group having 11 to 23 carbon atoms, and a hydroxyalkenyl group having 11 to 23 carbon atoms. Represents any group.)

R ^{5 to} R ^{7 in} the general formula (3) each independently represent a hydrogen atom or a group represented by the general formula (4), but not all become a hydrogen atom, and at least one of them is This is a group represented by Formula (4). Specifically, when one group represented by the general formula (4) is contained, it becomes a monoglyceride, when two groups are contained, it becomes a diglyceride, and when three groups are contained, it becomes a triglyceride.

R ^{8 in the} general formula (4) is selected from the group consisting of an alkyl group having 11 to 23 carbon atoms, an alkenyl group having 11 to 23 carbon atoms, a hydroxyalkyl group having 11 to 23 carbon atoms, and a hydroxyalkenyl group having 11 to 23 carbon atoms. Represents any group of Examples of the alkyl group having 11 to 23 carbon atoms include undecyl group, isoundecyl group, dodecyl group, isododecyl group, tridecyl group, isotridecyl group, tetradecyl group, isotetradecyl group, pentadecyl group, isopentadecyl group, hexadecyl group, Isohexadecyl group, heptadecyl group, isoheptadecyl group, octadecyl group, isooctadecyl group, nonadecyl group, isononadecyl group, eicosyl group, isoeicosyl group, heneicosyl group, isoheneicosyl group, docosyl group, isodocosyl group, trieicosyl group, isotricyl group Examples include an eicosyl group.

  Examples of the alkenyl group having 11 to 23 carbon atoms include an undecenyl group, an isoundecenyl group, a dodecenyl group, an isododecenyl group, a tridecenyl group, an isotridecenyl group, a tetradecenyl group, an isotetradecenyl group, a pentadecenyl group, and an isopentadecenyl group. Hexadecenyl group, Isohexadecenyl group, Heptadecenyl group, Isoheptadecenyl group, Octadecenyl group, Isooctadecenyl group, Nonadecenyl group, Isononadecenyl group, Eicocenyl group, Isoeicosenyl group, Heneicosenyl group, Isohenecocenyl group Nyl group, dococenyl group, isodococenyl group, trieicocenyl group, isotrieicocenyl group and the like can be mentioned.

  As a C1-C23 hydroxyalkyl group, what substituted the hydrogen atom of the group mentioned above as an alkyl group by the hydroxyl group etc. are mentioned, for example. Moreover, as a C1-C23 hydroxyalkenyl group, what substituted the hydrogen atom of the group mentioned above as an alkenyl group by the hydroxyl group etc. are mentioned, for example.

When all three groups of R ^{5 to} R ⁷ are groups represented by the general formula (4), the general formula (3) becomes a triglyceride. Triglycerides are known as fats and oils, but those used in the present invention may be natural fats or synthetic fats. Examples of natural fats and oils include linseed oil, olive oil, cacao butter, sesame oil, rice bran oil, safflower oil, soybean oil, camellia oil, corn oil, rapeseed oil, palm oil, palm kernel oil, castor oil, sunflower oil, cottonseed oil, Examples include vegetable oils such as coconut oil, animal fats such as beef tallow, pork tallow, lanolin, milk fat, fish oil, and whale oil. Examples of the synthetic fats and oils include those obtained by transesterification between different types of natural fats and oils and transesterification between natural fats and oils and arbitrary fatty acids.

Of the three groups of R ^{5 to} R ⁷ , when two are groups represented by the general formula (4) and the remaining one is a hydrogen atom, the general formula (3) becomes a diglyceride. Examples of diglycerides include those obtained by changing only one acyl group of any of the oils listed above to hydrogen atoms.
When one of the three groups of R ^{5 to} R ⁷ is a group represented by the general formula (4) and the remaining two are hydrogen atoms, the general formula (3) becomes a monoglyceride. Examples of monoglycerides include those obtained by changing two acyl groups of any of the oils listed above to hydrogen atoms.

Among these, those having a hydroxyl group are preferable because the lubricity is particularly good and the molding density can be increased. Specifically, R ⁸ is a fatty acid triglyceride, diglyceride or monoglyceride containing a hydroxyalkyl group or a hydroxyalkenyl group. A diglyceride has one hydroxyl group in the molecule, a monoglyceride has two hydroxyl groups, and a triglyceride having a hydroxyalkyl group or the like has three hydroxyl groups in the molecule. Therefore, a triglyceride having a hydroxyalkyl group or the like is more preferable. Examples of triglycerides having a hydroxyl group include castor oil and lanolin among natural fats and oils.

  The blending amounts of the fatty acid amide (A), the N, N′-alkylenebis fatty acid amide (B) and the fatty acid glyceride (C) are not particularly specified, but (A) / (B) = 1 because the lubricity becomes good. / 9 to 9/1 (mass ratio) is preferable, and (A) / (B) = 3/7 to 7/3 (mass ratio) is more preferable. Moreover, it is preferable that (C) component is 0.5-10 mass% with respect to the total amount of (A), (B), and (C), and 1-5 mass% is more preferable. If it is less than 0.5% by mass, molding at high pressure in metallurgy may not be possible, and if it exceeds 10% by mass, secondary agglomeration may occur and the density of the sintered part may be non-uniform.

  The lubricant composition for metal powder metallurgy of the present invention contains the components (A), (B) and (C) as essential components. Although there is no regulation in these mixing forms, it is preferable to uniformly mix the three components in order to maximize the lubricity. In order to mix uniformly, after melt | dissolving and mixing all the components at the temperature more than melting | fusing point of each component, for example, about 150-180 degreeC, it should just make it return to normal temperature and solidify. The form after uniformly mixing the three components is preferably in the form of a powder because it is then mixed with the metal powder. The method for making the powder is not particularly specified, and examples thereof include a method of obtaining a powder by pulverization using a pulverizer, spray spraying, or the like. Moreover, it is preferable that the shape of the said fine powder is spherical. This is because by increasing the fluidity of the fine powder in a spherical shape, there is an effect of preventing the caking of the fine particles and improving the mixing property with the metal powder. Moreover, it is preferable to manufacture by spray spraying at the point from which uniform spherical powder with a narrow particle diameter distribution is obtained.

  When solidifying by returning to room temperature, the lubricant composition may not completely crystallize when rapidly cooled, and may solidify in a so-called metastable state in which it is stable in an unstable state. The phase solidified in this metastable state is called a metastable phase (α phase), but a lubricant composition containing a metastable phase is a completely crystallized stable phase (β phase) obtained by slow cooling. Compared with, there are cases where the molding density of the metal green compact does not increase. Therefore, when the molten lubricant composition is cooled and solidified, it is preferable to cool slowly without quenching. Specifically, if the molten lubricant composition is made into a powder by spraying or the like, the atmospheric temperature is 40 ° C. or higher and less than the melting point of the mixture of the above three components (for example, 45 ° C. to 100 ° C.). It is preferable to spray in the tank, and then let it stand and lower to the same temperature as room temperature (natural cooling), and more preferably leave it at 20 to 40 ° C. for 1 hour. Regardless of the cooling method, the preferred lubricant composition of the present invention is such that the resulting lubricating oil composition is completely crystallized. Whether the resulting solidified product contains a metastable phase can be determined by X-ray crystal structure analysis or differential scanning calorimetry.

  Further, the particle diameter of the fine powder is preferably 5 to 100 μm, more preferably 10 to 30 μm in terms of median diameter. A large amount of labor is required to obtain a particle size of less than 5 μm, and if it exceeds 100 μm, the molding density of the metal green compact may not increase.

  The lubricant for metal powder metallurgy of the present invention is used by mixing with metal powder. The metal powder that can be used is not particularly limited, and a known metal powder used for metallurgy may be used. Examples of such metal powders include, in addition to metal powders such as iron, copper, titanium, tungsten, molybdenum, nickel, and chromium, iron-nickel alloys, iron-cobalt alloys, iron-molybdenum alloys, iron-silicon alloys, iron- Examples thereof include metal powders such as nickel-copper-molybdenum alloys and iron-chromium-nickel-molybdenum alloys.

  Although the usage-amount of the lubricant for metal powder metallurgy of this invention in the metal powder composition of this invention is not specifically limited, The addition amount of the said (A) component is preferably 0.001-10 mass% with respect to metal powder. More preferably, the amount may be 0.01 to 5% by mass, and more preferably 0.1 to 2% by mass. If the amount is less than 0.001% by mass, the effect may not be obtained. If the amount exceeds 10% by mass, the fluidity, the apparent density, or the molding density of the metal green compact may be adversely affected. .

  The metal powder composition of the present invention does not refuse the addition of known additives that can be used in lubricants for metal powder metallurgy, and for example, graphite, polyethylene wax, thermoplastic elastomer, polyamide, heat, depending on the purpose of use. Polymer materials such as curable resins, synthetic esters such as paraffin, carnauba wax, montan wax, pentaerythritol fatty acid ester, ethylene glycol fatty acid ester, polyether, and the like can be added.

  Hereinafter, the present invention will be specifically described by way of examples. In the following examples and the like,% is based on mass unless otherwise specified.

<Manufacture of lubricant>
Each sample of Examples 1-12 and Comparative Examples 1-13 was melt-mixed at 160 ° C. and then sprayed at a compressed air pressure of 0.25 MPa using a spray sprayer in an air-cooled tank adjusted to an atmosphere of 50 ° C. After spraying, heating for keeping the air-cooled tank was stopped and the mixture was left to cool to room temperature. After cooling, particles obtained after removing large particles using a 166 mesh (mesh size: 90 μm) classification screen were used for the test. In Example 13, a test lubricant was prepared in the same manner as described above except that the atmosphere in the air-cooled tank was adjusted to 28 ° C. and the particles after spraying were rapidly cooled.

<Test method>
A total of 500 g of 486 g of unoxidized atomized pure iron powder, 10 g of electrolytic copper powder and 4 g of graphite powder was put into a glass V-type mixer, and the lubricant shown in Table 1 below was applied to the mixed powder metal powder. 0.8% was added, and the rotation speed of the mixer was set to 25 to 30 rpm and mixed for 15 minutes. Thereafter, the compressibility test was performed in accordance with JPMA-P-13-1992 “Method for measuring the output power of metal green compact” defined by the Japan Powder Metallurgy Industry Association. 285 mm, effective length: 60 mm). Specifically, 7.0 g of the prepared mixed powder is precisely weighed, poured into the cavity of the above compaction test mold, sandwiched by upper and lower punches, compressed with a molding load of 800 MPa, and only the upper punch is extracted and a cylindrical cap And the extraction pressure was measured. The diameter and height of the compact were measured with calipers to determine the area of the curved surface, and the molding density and stress per unit area, that is, the extraction pressure, were determined and compared. The higher the molding density value, the better, and the lower the extraction pressure value.

<Difference in crystal structure by cooling method>
In order to confirm the crystal structure of the lubricants of Examples 7 and 13 having the same composition but different manufacturing methods, X-ray crystal structure analysis and differential scanning calorimetry were performed. The equipment used for the measurement is as follows. Each measurement result is shown in FIGS.
X-ray analyzer (XRD): Multi Flex (manufactured by Rigaku Corporation)
Differential scanning calorimeter (DSC): DSC6200 (manufactured by Seiko Instruments Inc.)

<Sample used>
A-1: oleic acid amide A-2: palmitic acid amide A-3: stearic acid amide B-1: N, N′-ethylenebis (oleic acid amide)
B-2: N, N′-ethylenebis (stearic acid amide)
B-3: N, N′-propylenebis (stearic acid amide)
C-1: Colza oil (palmitic acid 3%, stearic acid 1%, oleic acid 24%, linoleic acid 15%, linolenic acid 7%, gadoleic acid 12%, erucic acid 35%, other 3%)
C-2: soybean oil (palmitic acid 11%, stearic acid 4%, oleic acid 23%, linoleic acid 53%, linolenic acid 8%, others 1%)
C-3: Castor oil (stearic acid 1%, oleic acid 3%, linoleic acid 4%, ricinoleic acid 90%, other 2%)
C-4: Beef tallow (myristic acid 3%, palmitic acid 26%, palmitoleic acid 3%, stearic acid 22%, oleic acid 39%, linoleic acid 2%, others 5%)
C-5: oleic acid monoglyceride (in general formula (3), R ⁵ and R ⁶ are hydrogen atoms, R ⁷ is an oleic acid residue)
C-6: Dioleic acid monoglyceride (in general formula (3), R ⁵ is a hydrogen atom, R ⁶ and R ⁷ are oleic acid residues)
C-7: Polyethylene wax (weight average molecular weight 8000)
C-8: Polyethylene glycol (weight average molecular weight 11000)
C-9: Glycerin C-10: Ethylene glycol diolate

  From the XRD analysis results, diffraction patterns clearly different between Example 7 and Example 13 are obtained, and it can be confirmed that the crystal planes differ greatly depending on the cooling method. The greatest difference between the two analysis results is the difference in the intensity of the peak in the vicinity of 2θ of about 21 °. Since Example 7 has a high Bragg reflection intensity, the crystallinity is higher than that of Example 13 and is stable. It is estimated that there are many β phases.

From the DSC analysis results, in Example 13, a metastable α-phase peak was observed around 61 ° C., and a stable β-phase was observed around 95 ° C. On the other hand, in Example 7, there was no metastable α phase and only a stable β phase was observed.
From the above results, it can be confirmed that Example 7 does not include a metastable α phase and is composed only of a stable β phase having high crystallinity, and Example 13 has a crystal structure including a metastable α phase. It was.

Claims (6)

The fatty acid amide (A) represented by the following general formula (1), the N, N′-alkylenebis fatty acid amide (B) represented by the following general formula (2), and the following general formula (3) The lubricant composition for metal powder metallurgy characterized by containing the fatty-acid glyceride (C) made.

(In the formula, R ¹ represents an alkyl group or an alkenyl group having 15 to 19 carbon atoms.)

(In the formula, R ² and R ³ each represent an alkyl group or an alkenyl group having 15 to 19 carbon atoms, and R ⁴ represents an alkylene group having 1 to 6 carbon atoms.)

(In the formula, R ^{5 to} R ⁷ each independently represent a hydrogen atom or a group represented by the general formula (4). However, any one or more of R ^{5 to} R ⁷ are represented by the general formula (4). It must be a group represented by

Wherein R ⁸ is selected from the group consisting of an alkyl group having 11 to 23 carbon atoms, an alkenyl group having 11 to 23 carbon atoms, a hydroxyalkyl group having 11 to 23 carbon atoms, and a hydroxyalkenyl group having 11 to 23 carbon atoms. Represents any group.)   The ratio of the fatty acid amide (A) to the N, N′-alkylenebisfatty acid amide (B) is (A) / (B) = 1/9 to 9/1 in terms of mass ratio, and (A), (B ) And the total amount of fatty acid glycerides (C), the ratio of (C) is 0.5 to 10% by mass. The lubricant composition for metal powder metallurgy according to claim 1. 3. The metal powder metallurgy according to claim 1, wherein any one or more of R ^{5 to} R ⁷ of the fatty acid glyceride (C) is a hydroxyalkyl group or a hydroxyalkenyl group having 11 to 23 carbon atoms. Lubricant composition.   The lubricant composition for metal powder metallurgy according to any one of claims 1 to 3, wherein the lubricant composition is a fine particle having a median diameter of 5 to 100 µm. (I) Fatty acid amide (A) represented by the following general formula (1), N, N′-alkylenebis fatty acid amide (B) represented by the following general formula (2), and the following general formula (3 A step of heating the mixture containing the fatty acid glyceride (C) represented by formula (I) above the temperature at which the mixture melts, and (ii) a spray for spraying the mixture. A method for producing the composition.

(In the formula, R ¹ represents an alkyl group or an alkenyl group having 15 to 19 carbon atoms.)

(In the formula, R ² and R ³ each represent an alkyl group or an alkenyl group having 15 to 19 carbon atoms, and R ⁴ represents an alkylene group having 1 to 6 carbon atoms.)

(In the formula, R ^{5 to} R ⁷ each independently represent a hydrogen atom or a group represented by the general formula (4). However, any one or more of R ^{5 to} R ⁷ are represented by the general formula (4). It must be a group represented by

Wherein R ⁸ is selected from the group consisting of an alkyl group having 11 to 23 carbon atoms, an alkenyl group having 11 to 23 carbon atoms, a hydroxyalkyl group having 11 to 23 carbon atoms, and a hydroxyalkenyl group having 11 to 23 carbon atoms. Represents any group.)   6. The lubricant composition for metal powder metallurgy according to claim 5, wherein the step of spraying the mixture is performed in an atmosphere of 40 ° C. or higher and lower than a temperature at which the mixture melts, and further includes a step of naturally cooling. Production method.

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