JP3342780B2 - Binder for metal powder injection molding, degreasing method using the same, and metal powder injection molded product obtained using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder for metal powder injection molding, a degreasing method using the same, and a method using the same.
Regarding the obtained metal powder injection molded body , more specifically, improvement of a binder used for imparting pressure moldability at the time of injection molding of a metal powder material, and further improvement of a metal powder material obtained by injection molding using the binder Degreasing method for removing binder from molded article and metal powder injection molding
The present invention relates to a metal powder injection molded article obtained using a binder .

[0002]

2. Description of the Related Art In general, a sintered product obtained by a metal powder injection molding method is formed by injection molding in which a binder is mixed with a metal powder material so as to impart press-moldability to form a molded body. It is manufactured by sequentially performing degreasing to remove the binder, and further sintering of the degreased molded body, so-called degreased body. This metal powder injection molding method has an advantage that a more complicated shape can be molded at once, and less post-processing is required, as compared with a metal powder molding method by press molding, for example. These advantages are particularly suitable for manufacturing small metal parts, and are also advantageous in terms of cost.

[0003]

However, in the metal powder injection molding method, the amount of the binder used for imparting hydrostatic pressure moldability is larger than in the ordinary powder metallurgy method. In the steps of degreasing and sintering, the molded article tends to lose its shape, bulge and crack. Moreover, in order to prevent the shape collapse, swelling and cracking, it is necessary to slowly progress the removal of the binder in the degreasing step. It takes days. Such shape loss, blistering, cracking, and long time required for the degreasing step are problems to be solved in the metal powder injection molding method.

[0004] As a binder focused on improving the shape loss of a molded article during degreasing, a binder composed of three kinds of so-called amide compound binder components disclosed in US Pat. No. 5,200,988 is used. In addition, a degreasing method has been employed in which the binder components of these three amide compounds are gradually and gradually vaporized by heating to remove the binder from the molded product. However, even if this binder is used, there is a problem that if the binder does not require more than two days for the degreasing step, the binder loses its shape, and causes blistering and cracking.

In addition, in this binder, the polyamide resin component, which is one of the above-mentioned three types of amide compounds, has a very high tackiness and is an elastomeric soft body. In order to ensure sufficient releasability, ethylene bislauric amide as a lubricant for remarkably hardening the polyamide resin component is used in an amount of 20 to 30.
It is an inevitable requirement to add up to% by weight. As a result, the polyamide resin component, which is the strength component of the binder, is transformed into a brittle wax-like substance, causing large solidification shrinkage during cooling in the mold, and causing the molded product to have an internal residual stress due to internal residual stress. Depending on the product, there are many problems such as cracks, cracks from the parting line, chipping of sharp edges at the corners of the pin holes, or cracks depending on the shape of the molded product.

Further, ethylenebislauric amide, which is an essential component for mold releasability, has a melting point (155 to 16).
In order to start discoloration due to oxidation from a relatively low temperature range of 170 ° C. or higher just above 0 ° C.), the temperature at the time of kneading with the metal powder material, the injection molding temperature, and other injection molding in consideration of thermal stability. Care must be taken not to degrade the binder characteristics such as conditions (eg, injection pressure, holding pressure, injection speed, gate size, etc.) and the mixing ratio of the metal powder material and the amount of the binder, and the decomposition component is remarkable. Since it becomes water-absorbing, there is a problem that the hydrolysis of the binder is eventually gradually caused to make molding impossible.

[0007] In addition to the problems in management, in the case of a kneaded product of a very fine and active metal powder material such as carbonyl iron powder material of 5 μm or less and a binder, particularly up to 20 to 30% by weight. The added ethylenebislauric acid amide seems to accelerate the thermal decomposition due to the catalytic function of the carbonyl iron powder material. For example, the carbonyl iron powder material and a binder containing a large amount of ethylenebislauric amide seem to be present. At the time of kneading with, it is necessary to consider the amount of the carbonyl iron powder material and the binder so that excessive shear stress is not applied, and control of the kneading temperature, etc.
Depending on the conditions, there is a danger of being unmoldable. When vacuum sintering is performed at 1200 ° C. after degreasing in an N ₂ gas atmosphere, the concentration of carbon remaining from the binder in the sintered body due to the final temperature of degreasing fluctuates greatly, and carbon within the solid, between solids, and between lots of the sintered body is changed. The variation of the amount is large, and if it is remarkable, it may lead to danger such as erosion during sintering. It is necessary to substitute a thermally and chemically more stable substance other than lauric amide.

In this binder, the C ₃₆ diacid used as a dimer acid as a main raw material of the polyamide resin component, which is one of the above-mentioned three amide compounds, has a chemical structure having a cyclic structure. Because of its main component, when it encounters moisture in the air, it first makes it easy to take in moisture between its C ₃₆ diacid molecules, and then gradually induces hydrolysis, eventually making molding impossible. There is.

[0009] The above-mentioned matter is strict when using a kneaded product of a metal powder material and a binder, and when reusing sprues and runners other than product parts inevitably generated during injection molding. There is a problem that it becomes a great obstacle in reusing resources, such as management of moisture absorption from the atmosphere and management of characteristics of the return kneaded material after injection molding.

Further, as described above, ethylenebislauric acid amide, which greatly deteriorates the binder strength, is used in an amount of 20 to 3%.
Since the addition is performed in the range of 0% by weight, the amount of the polyamide resin component to be added also increases in relation to the strength of the molded article, which effectively contributes to shortening the degreasing time and preventing the molded article from being deformed during degreasing. The amount of N, N'-diacetylpiperazine, which is the amide compound of No. 3, is limited to a small amount, and as a result, it is difficult to shorten the degreasing time.

As described above, by substantially reducing the amount of ethylenebislauric acid amide added, reducing the water absorption of the polyamide resin component, and further reducing the hydrolyzability, the essential plastic toughness is obtained. Is important to determine the success or failure of metal powder injection molding, for example, by making "binder selection" such that a large amount of N, N'-diacetylpiperazine can be added while fully exhibiting the above.

Also, as disclosed in, for example, Japanese Patent Application Laid-Open No. 62-297257, it is known to produce alumina ceramics using the same technique as the metal powder injection molding method. Even when compared with alumina ceramics, the true specific gravity of a metal powder material is usually 7 to 8 in the case of an iron-based alloy, which is about twice that of alumina ceramics. Accordingly, the true specific gravity of the molded product obtained by injection molding of the metal powder material is also about twice, and the molded product is easily damaged at the time of injection molding or handling after injection molding, or the molded product is easily deformed in the degreasing process. There is a problem. Thus, “selection of a binder” is an important factor that determines the success or failure of metal powder injection molding.

By the way, as a binder used in the metal powder injection molding method up to the present, Japanese Patent Publication No. Sho 61
A binder composed of binder components having different melting points is used as disclosed in Japanese Patent No. 48563/4863, and these binder components having different melting points are caused to flow out of the molded body in a liquid state gradually and gradually by heating to be absorbed. A degreasing method has been adopted in which a binder is removed from a molded body by absorbing the material. However, since this binder becomes liquid when it is removed from the compact, there is a problem that the compact cannot withstand its own weight during the degreasing step, and the compact is deformed, especially when a metal powder material having a large specific gravity is used. There is a point.

On the other hand, US Pat. No. 4,197,971 discloses a binder that focuses on improving the shape of a molded article during degreasing.
As disclosed in the specification of No. 18, a degreasing method is employed in which a binder component of a liquid oil is eluted from a molded body at room temperature using an organic solvent such as methylene chloride at room temperature to remove the binder from the molded body. ing. However, since the binder is composed of the binder component of the liquid oil, the shape retention strength of the molded article in the injection molding is very low, and the molded article after the injection molding is frequently damaged during removal from the mold. There is a point. Further, many organic solvents such as methylene chloride are not preferable from the viewpoint of the safety environment of workers, and a safer solvent extraction degreasing method is desired.

[0015] The main object of the present invention, in view of the problems described above, rapid decomposition vaporization by heat, degreasing method used need and metal powder injection molding a binder can shorten the degreasing time without it consider the expansion and The metal powder injection molding
An object of the present invention is to provide a metal powder injection molded product obtained by using a molding binder .

Another object of the present invention is to provide a binder for metal powder injection molding capable of significantly shortening the time required for the degreasing step while ensuring the shape retention of the molded body at the time of degreasing , a degreasing method using the same, and a degreasing method using the same. For metal powder injection molding
An object of the present invention is to provide a metal powder injection molded product obtained by using a binder .

Further objects of the present invention are to provide a binder for metal powder injection molding which is stable against moisture, a degreasing method by safe water extraction with water as a solvent, and the above metal powder injection method.
An object of the present invention is to provide a metal powder injection molded body obtained by using a binder for molding .

Still another object of the present invention is to provide injection molding,
Using a metal powder injection molding binder excellent in strength and toughness for improving product defects during degreasing, a degreasing method using the same, and using the metal powder injection molding binder
An object of the present invention is to provide an obtained metal powder injection molded body .

[0019]

According to the present invention, there is provided a binder for metal powder injection molding, wherein (a) an amide-based water-soluble substance and / or an amine-based water-soluble substance is contained in an amount of 40 to 70% by weight to achieve the above-mentioned object. %, And (b) a polyamide resin raw material (i) having an average of 8 or more carbon atoms interposed between amide groups, as a compatibilizer having an average of 8 or more carbon atoms interposed between amide groups. It is characterized by containing 25 to 60% by weight of a polyamide resin component obtained by mixing an aromatic bisamide (ii) to a substantially equal weight%.

As described above, since the polyamide resin component is mixed with the compatibilizer, the melting point of the polyamide resin component is adjusted (decreased), the water swelling property is reduced, and the releasability is further improved. Therefore, it is not necessary to add a large amount of a lubricant as in the related art, and it is possible to prevent the strength from being deteriorated by the addition of the lubricant. As the compatibilizer, an aromatic bisamide having a relatively low melting point and high heat decomposition resistance is used.

When the number of carbon atoms between the amide groups of the polyamide resin raw material is 10 or more on average, the polyamide resin raw material itself exhibits releasability, low water swelling property, heat resistance, Since it is not necessary to use a solvent, the binder for metal powder injection molding according to the present invention provides (a) an amide-based water-soluble substance and / or
Or 40 to 70% by weight of an amine-based water-soluble substance, and (b) 25 to 60% by weight of a polyamide resin component substantially consisting of a polyamide resin raw material having an average of 10 or more carbon atoms sandwiched between amide groups. Is also characterized.

Further, the binder for metal powder injection molding of the present invention further contains a lubricant in an amount of 0 to 15 to improve the releasability.
% By weight.

An amide-based water-soluble substance is a substance having an amide group, and is classified into a substance having no benzene ring in a chemical structure and a substance having a benzene ring. Examples of those not having a benzene ring include acetamide, propynamide, alloxan (monohydrate), ethyl urethane, ethylene urea, glycol amide, heptanoamide, methyl acetamide, methyl acetyl urea,

[0024]

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Examples include trimethylurea and ethyl carbamate. Examples of those having a benzene ring include nitrobenzamide (o), nitrobenzhydrazide (o), phenylsemicarbazide (1) (C ₆ H ₅ N
HCO ₂ C ₆ H ₅ ), phenylcarbamic acid ester (C ₇ H ₇ C ₆ H ₄ O ₂ CNH ₂ ), toluylamide (o), toluylamide (p), acetaminophenol, acetonaphthalide, aminobenzamide ( o). One type or a mixture of two or more types including those having no benzene ring and those having a benzene ring can be used as the amide-based water-soluble substance.

The amine-based water-soluble substance has an amino group.
Substance, for example, about 1 mole of hexahydropiperazine
And about 2 moles of acetic acid obtained by dehydration copolymerization in a conventional manner.
N, N'-diacetylpiperazine, which is a secondary amine
Is mentioned. In addition, amino as primary amine type
Dimethylaniline (p), aminopyridine (3)
(Β), aminoquinolene (2) (α) (NH_TwoC₉H₈
N), aminoquinolene (3) (β), diaminohydrazo
Benzene (p) ((H_TwoNC₆H_FourNH)_Two), Hex
Methylenediamine, histamine, menthylamine
(1), naphthylamine (β), nitro-p-aminophenyl
Enol (3), nitroaniline (o), nitrophenyl
Ruhydrazine (p), nitrosoaniline (p), phenyl
Luaniline (p), phenylethylamine (β),
Nilendiamine (m), Toluylenediamine, Toluire
Diamine (1; 2, 4), toluylenediamine (1;
2,5), triaminobenzene (1, 2, 3), tria
Minobenzene (1,2,4), triethylenetetramine
Acetyl-p-fe
Nilendiamine, aminopyridine (2) (α), diphor
Milhydrazine ((NHCHO) _Two), Dipyridyl
(4,4 '), dipyridyl (3,3'), formylfe
Nylhydrazine (β) (C₆H_FiveNHNHCHO),
Lucose phenylhydrazone (C₆H_FiveNHN = C₆H
₁₂O_Five), Hydroxyethylethylenediamine (HOC)
H_TwoCH_TwoNHCH_TwoCH_TwoNH_Two) 、 Hydroxypyri
Gin, methylamino-p-hydroxybenzoic acid (3),
Methylbenzimidazole (2),

[0027]

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Examples include methylindole (2), nitrophenylhydrazine (p), phenylglycine (N), and triazole. These may be used alone or as a mixture of two or more, including primary amines and secondary amines, as amine-based water-soluble substances. Further, an amide-based water-soluble substance and an amine-based water-soluble substance may be used in combination.

Since amide-based and amine-based water-soluble substances have an amide group and an amino group, they are compatible with the polyamide resin component constituting the binder. These water-soluble substances
In any case, those having a melting point of 190 ° C. or less and a boiling point of 175 ° C. or more are preferable. If the melting point exceeds 190 ° C., the fluidity of the binder tends to be impaired, and the injection moldability tends to be impaired. Further, when the boiling point is lower than 175 ° C., at the time of kneading or injection molding of the metal powder material and the binder,
It tends to volatilize more selectively in the binder, which tends to hinder the stability of the injection molding and the reuse of the return material. These water-soluble substances are 1g in 100cc water
It is sufficient to dissolve the above, but if 10 g or more is dissolved, high extraction efficiency can be obtained.

[0030] The polyamide as the resin material C ₄₄ diacid used in it is conceivable that mainly those and cyclic chemical structure composed mainly of linear chemical structure, which mainly cyclic chemical structure Is not preferred because it has a problem due to the absorption of moisture as in the case of the C ₃₆ diacid having a cyclic chemical structure as a main component. Accordingly, the C ₄₄ diacid used in the present invention, it is preferable to mainly the chemical structure of the linear. Such C ₄₄ diacid, typically a polymerized fatty acid obtained by bimolecular polymerization of unsaturated fatty acids, for example, the formula:

[0031]

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The compound may be: Such C ₄₄ diacid is readily available in the market. Specifically, for example, Unichema (Unichem, the Netherlands)
a International) Pripol 100
4 (PRIPOL 1004). The Pripol 1004 is a rapeseed oil as a raw material, considered to C ₄₄ diacid linear account for about 90 mol%. It is also possible to use grape, the seed oil of mustard as a raw material for C ₄₄ diacid. It is to be noted that even if C ₃₆ diacid has a linear chemical structure, it can be basically treated almost in the same manner as C ₄₄ . Specifically, for example, Prepolo 1013 (PRIP manufactured by Uniqema Corporation)
OL 1013) is a linear structural components of about 23 mole%, Pripol 1008 (PRIPOL 1008) is considered to linear structure component accounts for about 37%, used as a mixture with C ₄₄ diacid of the foregoing It is also possible.

The aliphatic dicarboxylic acids having 6 to 10 carbon atoms used for the polyamide resin raw material include, for example, adipic acid (C ₆ diacid), azelaic acid (C ₇ diacid), and phthalic acid (C ₈ diacid). , Containing a six-membered ring structure), sebastinic acid (C
₁₀ diacids) and are also readily available on the market. Note that one or more of these fatty acid group dicarboxylic acids may be used as a mixture.

[0034] In the present invention, in addition to the aliphatic dicarboxylic acid and xylylenediamine, 7: 3 to 3: C ₄₄ described above in a molar equivalent weight range of 7 diacid such as ethylenediamine and / or hexamethylenediamine It is mixed and dehydrated and copolycondensed to obtain a polyamide resin raw material having a substantially amorphous shape, high elasticity, low water absorption and preferably having an average molecular weight of 20,000 or more. This xylylenediamine has a benzene ring in the chemical structure, and is considered to improve the water absorption and the thermal decomposition of the polyamide resin raw material. The C ₄₄ and C ₃₆ diacids significantly increase the average number of carbon atoms between the amide groups, and in particular, lower the melting point of the polyamide resin raw material to make it superior to nylon 6,6 in water absorption. It is considered to play a major role.
The weight ratio of the polyamide resin component is selected so that the average carbon number between the amide groups is 8 or more.
The average molecular weight of the polyamide resin raw material is 50,000
Alternatively, even if it is 100,000 or more, there is no significant effect on the present invention.

[0035] Therefore, in metal powder injection molding binder according to the present invention, the polyamide resin component, for example, C ₃₆ diacid, C ₄₄ diacid or their C ₃₆ diacid and C,
The mixture of ₄₄ diacids is prepared by copolycondensing an aliphatic dicarboxylic acid having 6 to 10 carbon atoms, xylylenediamine, and ethylenediamine and / or hexamethylenediamine so that the number of carbon atoms sandwiched between amide groups is reduced. The polyamide resin raw material (i) having an average of 8 or more is mixed with an aromatic bisamide (ii) as a compatibilizer having an average of 8 or more carbon atoms sandwiched between the amide groups to approximately equal weight%. It can be made.

As described above, the polyamide resin raw material
The number of carbon atoms sandwiched between A bromide group may not use the compatibilizer in the case where the average 10 or more. Therefore, the polyamide resin component, for example, a _{C 36 diacid, C 44} diacid or a mixture thereof _{C 36} diacid and _{C 44} diacids, aliphatic dicarboxylic acids having 6-10 carbon, xylylenediamine And a polyamide resin raw material having an average of 10 or more carbon atoms between amide groups obtained by copolycondensation with ethylenediamine and / or hexamethylenediamine.

The average molecular weight of these polyamide resin raw materials is preferably 20,000 or more.

As described above, when the water absorption and the hydrolyzability of the polyamide resin component are taken into consideration, and the mold releasability as a binder is sufficiently taken into consideration, C ₃₆ and C ₄₄ 2 in the polyamide resin component are taken into consideration. The acid (dimer acid) is considered to deteriorate the releasability from the mold. In the present invention, an effective lubricant is added in consideration of this point. However, since addition of the lubricant is preferably minimized, nylon having a relatively excellent water absorption compared to nylon 6 or the like is preferred. 11
Or, based on nylon 12, compatibilized with an aromatic bisamide to adjust the melting point useful as a binder;
Furthermore, remarkable reduction in water absorption and improvement in alcohol resistance can be achieved, and degreasing by solvent extraction with water and / or a hydroalcoholic solvent becomes possible.

Therefore, in the binder for metal powder injection molding according to the present invention, the polyamide resin component is converted into a polyamide resin raw material having an average of 8 or more carbon atoms between amide groups mainly composed of nylon 11 and nylon 12, for example. On the other hand, an aromatic bisamide as a compatibilizer having an average of 8 or more carbon atoms interposed between amide groups can be mixed to approximately an equal weight%.

When the number of carbon atoms sandwiched between the amide groups of the polyamide resin raw material is 10 or more on average as described above, the compatibilizer may not be used. Therefore, the polyamide resin component is, for example, nylon 11,
It can be substantially composed of a polyamide resin raw material having an average of 10 or more carbon atoms sandwiched between amide groups mainly composed of nylon 12.

The average molecular weight of these polyamide resin raw materials is preferably 13,000 or more.

The melting point or glass transition temperature of the polyamide resin raw material is preferably adjusted to about 190 ° C. or less.

The nylon 11 and nylon 12 can be obtained by dehydrating and condensing ω-aminoundecanoic acid and ω-aminolauric acid, for example. The polyamide resin raw material having an average of 8 or more carbon atoms between amide groups mainly composed of nylon 11 and nylon 12 is obtained by adding other nylon components such as nylon 2, 36 and nylon 2 to nylon 11 and nylon 12. , 44, nylon 6, nylon 6,8, nylon 6,10 nylon 6,36, nylon 6,44, ether and the like.

As the raw material of the polyamide resin component, those which are already widely commercially available can be used without any trouble. For example, Nylon 12 includes Daiamide A1709P and L1724K manufactured by Daicel Corporation, and nylon 12-ether copolymer includes Daiamide E40S3 manufactured by Daicel Corporation.

In the present invention, the compatibilizer used for the purpose of improving the water resistance and reducing the hydrolyzability of the polyamide resin component, adjusting the melting point and preventing the strength from being reduced by the addition of a lubricant, has a chemical structure. M-xylene bisstearic acid amide, N, N'-distearyl isophthalic amide, which is an aromatic bisamide having a benzene ring (six-membered ring) structure and having a low melting point and extremely excellent thermal stability;
There is N, N'-distearylterephthalamide. Thus, by using one or more of these as a mixture, the compatibility of the base polyamide resin raw material with the above-mentioned compatibilizer is enhanced, and the water absorption of the polyamide resin raw material itself is improved, and The average carbon number between the amide groups in the chemical structure of the resin raw material was set to be 8 or more of the average carbon number between the amide groups in the compatibilizer.
By improving the chemical structure of the polyamide resin raw material in this way, the plastic toughness of the original polyamide resin raw material is increased, and the releasability is improved at the same time. Can be eliminated or the amount of addition can be significantly reduced, thereby preventing brittle waxing of the binder. The method of adding the compatibilizer may be a mixing method as described above or a method of simultaneously performing copolycondensation during the copolycondensation of the polyamide resin raw material. In addition, the above-mentioned C is obtained by compatibilization of the xylylenebisstearic acid amide having a benzene ring (six-membered ring) structure and N, N'-distearylisophthalic acid component.
The problem of water absorption due to the cyclic structure of ₃₆ , _C44 diacid can be substantially eliminated. Further, since the strength deterioration due to the addition of a lubricant that enhances the wax property such as ethylenebislauric amide can be significantly reduced and the thermal stability is significantly improved, the amount of the amide-based or amine-based water-soluble substance added is reduced. A large amount can be added. Xylerine bisstearic acid amide is commercially available. For example, a commercially available product of PXS manufactured by Nippon Kasei Co., Ltd. can be used in the present invention without any trouble.

As the lubricant used in the binder for metal powder injection molding according to the present invention, all the lubricants usually used for metal powder injection molding are effective, for example, fatty acids and derivatives of fatty acids such as esters, amides and metal salts. Is mentioned. Among these fatty acids and their derivatives, fatty acid amides having an amide group in their structure and having a linear structure as a main component, from the viewpoint of binder strength due to separability or partial compatibility with other components, -Substituted fatty acid amides are preferred. Also, substituted ureas are preferably used as a lubricant.

Examples of the fatty acid amide include lauric acid amide, stearic acid amide, oleic acid amide, erucic acid amide, ricinoleic acid amide, 12-hydroxystearic acid amide, and special fatty acid amide.

Both saturated and unsaturated N-substituted fatty acid amides can be used. The saturated ones include N, N'-ethylenebislauric amide,
N, N'-methylenebisstearic acid amide, N, N'-
Ethylene bisstearic acid amide, N, N'-ethylenebisoleic acid amide, N, N'-ethylenebisbehenic acid amide, N, N'-ethylenebis-12-hydroxystearic acid amide, N, N'-butylenebis Stearamide, N, N'-hexamethylenebisstearic acid amide, N, N'-hexamethylenebisoleic acid amide, and N, N'-xylylenebisstearic acid amide. Further, those unsaturated, such as N- oleyl stearic acid amide, N- oleyl oleic acid amide, N- stearyl stearic acid amide, N- stearyl oleic acid amide, N- oleyl Pas palmitic acid amide, N- stearyl erucamide Acid amide, N, N′-dioleyl adipamide, N, N′-distearyl adipamide, N, N′-dioleyl sebacamide,
N, N'-distearyl sebacamide, N, N'-distearyl terephthalamide, N, N'-distearyl isophthalamide.

N, N'-ethylenebislauric acid amide and N, N'-ethylenebisstearic acid amide are obtained by dehydration condensation of ethylenediamine with lauric acid and stearic acid, which are saturated aliphatic monocarboxylic acids. However, many of the above-mentioned various saturated or unsaturated fatty acid amides and N-substituted fatty acid amides are commercially available, and these commercially available products can be used in the present invention without any trouble. For example, as N, N'-ethylenebisstearic acid amide, Slipax E manufactured by Nippon Kasei Co., Ltd. can be mentioned.

Examples of the substituted urea include N-butyl-N 'stearyl urea, N-phenyl-N' stearyl urea, N-stearyl-N'-stearyl urea, xylylene bisstearyl urea, and toluylene bis stearyl urea. , Hexamethylene bisstearyl urea, diphenylmethane bisstearyl urea, diphenylmethane bis lauryl urea.

[0051]

According to the present invention, since the amide-based and amine-based water-soluble substances are slowly vaporized in the early stage of the degreasing process by thermal decomposition to form a passage, other binder components are easily released, and the degreasing process is performed. Shape retention of the molded body is maintained, sound degreasing without problems such as blisters is reliably performed, and the time required for the degreasing step can be significantly reduced. (However, since the vaporized component is also liquefied before being vaporized, there is generally a limit to the heating rate for degreasing in order to completely prevent deformation during degreasing.
Further, in order to remarkably widen this limit, it is necessary that the amount of the vaporized component can be added more significantly. )

Further, when an amide-based or amine-based water-soluble substance is extracted with water, since the amount of the amide-based or amine-based water-soluble substance is as large as 40 to 70% by weight, degreasing with a water solvent is a considerable step in the degreasing step. , The rate of time-consuming degreasing by heating is reduced, and the degreasing time can be shortened. In addition, since the amount of degreased components by heating is small, there is almost no need to consider rapid decomposition and vaporization and expansion due to the heat of the binder. The amount of the amide-based or amine-based water-soluble substance used is 40 to 70% by weight based on the entire binder. If the amount is less than 40% by weight, a large amount of degreasing time is required to perform sound thermal degreasing or degreasing by aqueous solvent extraction in terms of shape retention. On the other hand, if the content exceeds 70% by weight, it is difficult to remove the molded product from the viewpoint of strength deterioration. It should be noted that, rather preferably is 45 to 60% by weight.

In the present invention, the raw material of the polyamide resin is C
In order to use the ₄₄ diacid as one of raw materials, as compared with the case of using a C ₃₆ diacid as a raw material, it is possible to configure the tough binder by polymeric effect First, the degreasing time as described above The weight ratio of the amide-based and amine-based water-soluble substances, which greatly affects the water content, can be relatively increased, and the degreasing time can be shortened. Further, xylylene polyamide resin material Len acid amide,
N, N'-distearylterephthalamide, N, N'-
By compatibilizing aromatic bisamides such as distearyl isophthalamide to improve the releasability and the water absorption by partial crystallization of the polyamide resin component, lubricants that cause significant strength deterioration it is possible to greatly reduce the amount can substantially improve the lack of polymerization effect of C ₃₆ diacids mentioned above,
For the same reason as described above, the degreasing time can be greatly reduced.

[0054] Furthermore, (1) the chemical structure as a suppression of the density of the amide bond by a straight-chain structure using a C ₄₄ diacid mainly, the average number of carbon sandwiched between the above-mentioned amide group (hereinafter , Average carbon number), and further, the reduction of the amount of water taken into the polyamide resin component by achieving a polymerizing effect, and (2) the water absorption by compatibilizing the aromatic bisamide described above. (3) a reduction in the water absorption of the thermally decomposed component due to a significant reduction in the thermally unstable lubricant; and (4) a higher carbon number such as ethylenebisstearic amide which improves the releasability than ethylenebislauric amide. By combining improvements such as the adoption of a more thermally stable lubricant, the amount of water taken up by the binder is reduced, the affinity between molecules is reduced due to the water taken up, and furthermore, significant reduction is caused by hydrolysis. There troubles due to moisture uptake of deterioration of pressure-forming properties is avoided. Therefore, no special control of the binder for moisture is required, and the binder,
The kneaded product of the binder and the metal powder material, and also the reusability of sprues and runner parts other than the product parts inevitably generated during injection molding are ensured.

In the present invention, the polyamide resin component is used in an amount of 25% by weight or more based on the total amount of the binder in order to carry a relatively heavy metal powder material in the injection molded body.
If it is used in an amount less than 25% by weight, there is a problem in taking out the molded article from the mold after injection molding, and further, in breaking the molded article during handling. Preferably, it is used at a weight ratio of 60% by weight or less based on the total binder amount.
The content of the aromatic bisamide contained as a compatibilizer in the polyamide resin component is up to 7 on a weight basis.
Although it is possible to use up to 0% by weight, it is preferable that the amount is less than approximately equal to the weight of approximately equal weight% since it is already hard at approximately equal weight% and the molded article may be damaged at the time of molding.

Further, since the lubricant functions mainly for the releasability of the molded article from the mold at the time of injection molding, the binder property is changed from about 15% by weight or more to the total binder amount. It is preferable to use 0 to 15% by weight, preferably about 10% by weight, in order to make the composition significantly waxy. However, when an aromatic bisamide is added as a compatibilizer in an amount of 15% by weight or more of the total binder amount, the function as a binder for metal powder injection molding can be exhibited without a special need for a lubricant.

It is also possible to use ethylene bislauric amide as a lubricant. This ethylenebis lauric amide has problems such as thermal stability as described above. However, if the amount of the ethylene bis lauric amide used is 15% by weight or less of the total amount of the binder, the N ₂ gas of the molded body using the carbonyl iron powder material is used. The concentration of residual carbon in the sintered body after the degreasing in the atmosphere is kept substantially stable, and troubles in the quality of the sintered body are avoided. This residual carbon concentration is more stable as the thermal stability of the lubricant used is higher, and a bisamide (for example, an N-substituted bisamide compound) having more carbon atoms than ethylenebislauric acid has higher reliability.

As described above, the binder according to the present invention is improved so that the addition of a lubricant which leads to the deterioration of strength such as ethylenebislauric acid amide is minimized or not added, and the binder is of high toughness plastic type. Therefore, the occurrence of internal cracks during degreasing, which is considered to be caused by the residual stress generated in the molded product during injection molding, has been eliminated. The inspection process can be largely omitted.

The above-mentioned amide-based water-soluble substance, amine-based water-soluble substance, polyamide resin raw material , compatibilizer, and lubricant can be used in the form of a sheet, pellet, or powder by heating and melting and mixing. The binder thus obtained is usually used as a molding material by mixing with a metal powder material. Alternatively, as another method, the amide-based water-soluble substance and / or amine-based water-soluble substance, a polyamide resin raw material ,
The compatibilizer and lubricant may be directly mixed with the metal powder material and used as a molding material.

The mixing ratio of the binder to the metal powder material varies depending on the type of the metal powder material used, the size of the particles, the shape of the particles, and the like.
The used amount of the binder is 5 to 15 parts by weight with respect to parts by weight.

As the injection molding method of the metal powder material, any known injection molding method can be adopted.

The degreasing method according to the present invention comprises the following steps: (a) 40 to 70% by weight of an amide-based water-soluble substance and / or an amine-based water-soluble substance; A polyamide resin raw material having an average of 8 or more carbon atoms is mixed with an aromatic bisamide as a compatibilizer having an average of 8 or more carbon atoms sandwiched between amide groups up to approximately equal weight%. First, the amide-based water-soluble substance and / or the amide-based water-soluble substance is first formed from a molded article obtained by injection molding using a binder for metal powder injection molding containing 25 to 60% by weight of a polyamide resin component with a solvent mainly containing water.
Alternatively, the amine-based water-soluble substance is eluted, and then the polyamide resin component and the lubricant are removed by heating.

When the number of carbon atoms sandwiched between the amide groups of the polyamide resin raw material is 10 or more on average as described above, it is not necessary to use a compatibilizer. Therefore, the binder for metal powder injection molding according to the present invention is used. In order to achieve the above-mentioned object, the degreasing method using (a) comprises (a) 40 to 70% by weight of an amide-based water-soluble substance and / or an amine-based water-soluble substance, and (b) the number of carbon atoms sandwiched between amide groups. Average 1
First, a molded product obtained by injection molding using a metal powder injection molding binder containing 25 to 60% by weight of a polyamide resin component substantially consisting of a polyamide resin raw material of 0 or more is first treated with a solvent mainly composed of water. The amide-based water-soluble substance and / or the amine-based water-soluble substance are eluted, and then the polyamide resin component is removed by heating.

The amide-based water-soluble substances and / or
Alternatively, the amine-based water-soluble substance and the polyamide resin component are as described above, and the metal powder injection molding binder may contain a lubricant as described above. Further, the solvent mainly composed of water (aqueous solvent) may be not only water but also a mixture of water and an organic solvent such as alcohol as described above. It is considered that the extraction efficiency is improved by mixing the alcohol and the like.

[0065]

As described above, when the degreasing method using the aqueous solvent is used, it is not necessary to consider rapid decomposition and vaporization and expansion due to heat, and the amide-based water-soluble substance and / or
Alternatively, substantially the same effect can be obtained by using one of the above-mentioned substances as the amine-based water-soluble substance or by mixing two or more of them. It is also conceivable to use liquid substances such as dimethylformamide and dimethylacetamide. However, these dimethylformamides and the like cause a deterioration in the strength as a binder, so that the shape of a product to be applied is restricted. According to the degreasing method using the aqueous solvent, the degreasing time can be further shortened, and a component having a shape easily deformed at the time of degreasing, which is difficult according to the conventional thermal decomposition degreasing method, a heat decomposition type Easily applicable to parts that use metal powder materials that are likely to cause internal defects that may occur during degreasing heating, parts that use metal powder materials with a high specific gravity such as tungsten, and even large parts. Let it.

The present invention also relates to a method for injection-molding a metal powder material using the binder for metal powder injection molding according to the present invention.
The present invention relates to a metal powder injection molded product obtained by the above method.

[0067]

Next, examples and comparative examples of a binder for metal injection molding and a degreasing method using the same according to the present invention will be described in detail.

[0068] (A) mixed with a binder composition C ₄₄ diacid (Uniqema Corp. Pripol 1004) 13 mol, and azelaic acid _{(C 7} diacid) 7 moles, and ethylenediamine 7 moles, and xylylenediamine 13 mole And dehydration copolycondensation to give an average molecular weight of about 50,000.
No. 0 polyamide resin component (1) was obtained. The polyamide resin component (1) is adjusted so that the average number of carbon atoms between the amide groups in the aforementioned chemical structure is about 17.5.

Further, 13 mol of C ₃₆ diacid (Pripol 1008 manufactured by Unichema; linear component 37%), 7 mol of azelaic acid, 7 mol of ethylenediamine and 13 mol of xylylenediamine were mixed and dehydrated. By copolycondensation, a polyamide resin component (2) having an average molecular weight of about 40,000 was obtained. The aforementioned average carbon number of the polyamide resin component (2) is adjusted to about 14.9.

[0070] Moreover, C ₃₆ diacid (Yumikema Co. Poriporu 1008) and C ₄₄ diacid (Pripol 1004) in a weight ratio of 7: 10 moles of diacid mixed in a ratio of 3, and azelaic acid 10 mol, 10 mol of ethylenediamine and 10 mol of xylylenediamine were mixed and subjected to dehydration copolycondensation to obtain a polyamide resin component (3) having an average molecular weight of about 40,000. The polyamide resin component (3)
Adjusts the above average carbon number to 12.9.

Further, 1 mol of piperazine and 2 mol of acetic acid were mixed and subjected to dehydration copolycondensation to obtain N, N'-diacetylpiperazine. Also, N, N'-ethylenebislauric amide (Nippon Kasei Co., Ltd .: Slipax L, melting point 156-160 ° C.), N, N'-ethylenebisstearamide (Nippon Kasei Co., Ltd .: Slipax E, melting point 1)
42 to 146 ° C.) and N, N′-xylylenebisstearic amide (manufactured by Nippon Kasei Co., Ltd .: Slipax PXS, melting point: about 123 ° C.) were used as raw materials.

The polyamide resin components (1), (2) and (3) obtained as described above, N, N'-ethylenebislauric amide, N, N'-ethylenebisstearic amide, N′-xylylenebisstearic acid amide and N, N′-diacetylpiperazine were melt-mixed at a mixing ratio of the weight ratios shown in Tables 1 and 2 below, and after cooling, pulverized to obtain each of binders A to L, S and U were obtained.

[0073]

[Table 1]

[0074]

[Table 2]

As a polyamide resin raw material having an adjusted average carbon number between amide groups in chemical structure, nylon 12 having the above-mentioned average carbon number of 11 (A1709 manufactured by Daicel Corporation) is used.
P, density: 1.01, melting point: 178 ° C, water absorption: 0.9
%) And, the average carbon number of five nylon 6, nylon 6,
6 and a copolymer of nylon 12/6 / 6,6 (average carbon number adjusted to 7.7) (Daicel T Co., Ltd.).
171, density: 1.08, melting point: 150 ° C, water absorption;
2.0%), and a nylon 12 / ether elastomer copolymer having an average carbon number of 11 or more (E40S3 manufactured by Daicel, density: 1.01, melting point: 125 ° C., water absorption: 0.3%), etc. Was used as a raw material.

The raw material nylon resin components A1709P, T171, E40S3, N, N ′ selected as described above.
Xylylerine bisstearic acid amide, N, N'-diacetylpiperazine, N, N'-ethylenebisstearic acid amide, N, N'-ethylenebislauric acid amide are shown in Tables 1 and 2 below. Melt and mix at a mixing ratio of weight ratio, pulverize after cooling, and each binder a to g
I got

In particular, for the purpose of aqueous solvent extraction, the polyamide resin components (1) and (3), nylon 12 (Daicel A1709P) and N, N'-ethylenebislauric amide, and further, N, N ' Similarly, using acetamido, acetaminophenol or toluylenediamine in place of diacetylpiperazine, and melt-mixing in the same proportions by weight as shown in the following Tables 3 and 4,
After cooling, pulverize each binder M, N, V, W, X, Y,
m, v, x, y were obtained.

[0078]

[Table 3]

[0079]

[Table 4]

[0080] _{Furthermore, C 36} diacid (Uniqema Corp. Pripol 1013; linear component 23 mol%) 7 molar, was mixed with azelaic acid 13 mol, and ethylene diamine 13 mol, and xylylenediamine 7 moles Binder T shown in Table 6 using a polyamide resin component (5) having an average molecular weight of about 40,000 obtained by dehydration copolycondensation.
1, T2 was obtained. The polyamide resin component (5)
Is adjusted to about 9.6.

On the other hand, for comparison, the polyamide resin component (1) and nylon 12 (1709 manufactured by Daicel Corporation) were used for comparison.
P), N, N'-xylylenebisstearic acid amide,
N, N'-ethylenebislauric amide and N, N '
-Even with the combination of diacetylpiperazines,
Further , as shown in Table 7, binders O to R and or to that having different mixing ratios were obtained.

[0082]

[Table 5]

[0083]

[Table 6]

[0084]

[Table 7]

Further, for comparison, conventionally known binders SS, TT, XX, and
YY and YY were made in accordance with the gist of the present invention, and binders ZZ and yy having an effect of improving water absorption were obtained.

[0086]

[Table 8]

The binders YY and yy are C ₃₆ diacid (Pripol 1013 manufactured by Unichema; linear component of about 25%).
%), Azelaic acid, ethylenediamine, and xylylenediamine in equimolar amounts, and were subjected to dehydration copolycondensation to obtain a polyamide resin component (4) having an average molecular weight of about 40,000. It was obtained by melt-mixing at a mixing ratio of the above weight ratios. The average carbon number between the amide groups of the polyamide resin component is about 12.2.

[0088] Further, binder and ZZ, C ₃₆ diacid (Uniqema Corp. Pripol 1018) and C ₄₄ diacid (Pripol 1004) and in the weight ratio 7 described above: 10 moles of diacid mixed at a ratio of 3 , 10 mol of azelaic acid, 10 mol of ethylenediamine, and 10 mol of xylylenediamine, and the average molecular weight obtained by dehydration copolycondensation is about 40,0.
No. 00 polyamide resin component (3) is used. This polyamide resin component (3) has the aforementioned average carbon number of 12.9.
In each case, the molar ratio of the linear component in the chemical structure is increased to about 50 mol% or more.

(B) Method for Producing Sintered Body by Thermal Decomposition Degreasing (I) (II) (I) First, a spherical stainless fine powder material (SUS316L, average particle size: 1) produced by a gas atomizing method
0 micron) for each binder A to L, OR to R, SS
~ YY and a ~ g, or ~ r, were heated and kneaded at 140 ° C, cooled and pulverized. Next, a pressure of 660 kg / cm
^Under the condition of ^2, a top-shaped molded body as shown in FIG. 1 was obtained by injection molding. Subsequently, the formed body is degreased by raising the temperature from 20 ° C. to 320 ° C. in a heat circulating furnace in an air atmosphere at a wind speed of 1 to 1.5 m / sec over 24 hours, so that the remaining binder amount is before degreasing. After confirming that it was 8% or less, vacuum sintering was performed at 1350 ° C. for 1 hour.

The amount of the binder (powder material 10
0 parts by weight of binder, injection molding temperature, quality of molded product, shape, density and carbon content are shown in Table 9 below.
Was as shown in FIG.

[0091]

[Table 9]

[0092] The mark x in Table 9 indicates that no measurement was performed because a good sintered body was not obtained, and the binders SS to YY of the comparative example were originally contained in the alumina supporting powder during degreasing. The experiment must be performed under the same conditions without using a supporting powder in order to clarify the difference from the binders A to L according to the present invention.

(II) First, the carbonyl iron powder material (B
CS iron fine powder manufactured by ASF, average particle size: 5 microns) is heated and kneaded at 140 ° C using binders C, D, F, I, U, YY, c, e, and g, cooled and pulverized. did. Next, under the condition of a pressure of 660 kg / cm ² , FIG.
A molded body having a shape as shown in (1) was obtained by injection molding. Subsequently, _{N 2} of the molded body of the wind speed 1.0 m / sec
Room temperature to final temperature 350 in a gas circulating furnace
Degreased to ~ 450 ° C over 50-65 hours,
Vacuum sintering was performed at 200 ° C. for 1 hour. The reason was degreased time prolonged prevents as much as possible the deformation of the formed feature is to grasp the internal defect situation.

The amount of the binder used for the spherical carbonyl iron fine powder material of the sintered body thus obtained (the same as described above), the injection molding temperature, the final degreasing temperature, the quality of internal defects in the molded body, the shape, the density, and the carbon content The amounts are as shown in Table 10.

[0095]

[Table 10]

The cracks in the degreased body in Table 10 were X-
FIG. 3 shows the probability of occurrence of cracks inside the degreased body by a line inspection, and FIG. 3 shows the state of internal cracks in the degreased body using the binders F, YY, and c. However, if these compacts are annealed at 110 ° C. × 4H in an N ₂ gas atmosphere, the rate of occurrence of internal cracks can be greatly reduced, so that the cause of internal cracks is weak and solidification shrinkage occurs. It was presumed to be due to residual stress during injection molding due to the use of a large waxy binder.
(However, it is difficult to guarantee complete prevention of internal cracks.)

(C) Method for Producing a Sintered Body by Extraction with Water Solvent Extraction First, a similar spherical stainless steel fine powder material (SUS316L, average particle size: 1) produced by a gas atomizing method.
0 micron) for each binder A, F, G, H, J,
L, S, M, N, V, W, X, Y, YY, yy, ZZ,
The mixture was heated and kneaded at 140 ° C. using T ₁ , T ₂ and a to c, e to g, m, v, w, y, cooled, and ground. next,
Similarly, under the condition of a pressure of 660 kg / cm ^2, a top component as shown in FIG. 1 was obtained by injection molding. Subsequently, the molded body was placed in water at 25 ° C for 1,
After immersion for 2, 4 hours, a 1H drying treatment was performed at 100 ° C. FIG. 4 shows a representative result of calculating the residual binder amount by measuring the weight of the molded body after drying.

Next, the molded body degreased by the aqueous solvent extraction for 1, 2 and 4 hours as described above was used in a hot air circulating furnace having an air atmosphere of 1 to 1.5 m / sec in an air atmosphere at a wind speed of 1 to 1.5 m / sec. After a certain time, the temperature was raised from 20 ° C. to 320 ° C. to further degreasing, and after confirming that the remaining binder amount was 8% or less of that before degreasing, 1 g at 1350 ° C.
Vacuum sintered for hours. It should be noted that there was no problem in continuously degreasing by heating after the drying treatment at 100 ° C.

The amount of the binder used for the spherical stainless steel fine powder material of the sintered body (parts by weight of binder relative to 100 parts by weight of powder) obtained by the aqueous solvent extraction time thus obtained for 1, 2, and 4 hours, respectively, was determined by injection molding. The temperature, the quality of the compact, the shape, the density, and the carbon content are as shown in Table 11 below. In addition, all of the molded articles were good without cracking in 100 pieces.

[0100]

[Table 11]

[0101]

[Table 12]

(D) Test Results In Case of Only Decomposition by Thermal Decomposition Binder F among binders A to L contains a particularly large amount of ethylenebislauric amide, and thus exhibits a hard and brittle wax property. There were problems such as breakage and chipping in a mold after molding, and internal defects during degreasing. In addition, it was recognized that sufficient control was required in terms of controlling the carbon content of the sintered body. Further, binders G, I, and J are particularly excellent in terms of the strength and toughness of the molded product,
There was almost no difference between A to L in the shape retention and the sintered density of the molded body during degreasing, and good results were obtained. In each of the binders J, K, and L containing no lubricant, there was no trouble due to the releasability of the molded body from the mold at the time of molding.

The binder c among the binders a to g is altered in a wax state, and has almost the same problem as the binder F. Further, the binder d was not sufficiently compatible with xylylene bisstearic acid, so that a liquid phase component was separated during molding, and a sufficient molded body was not obtained due to remarkable deterioration of moldability. The sintering test could not be performed. Except for the binder d, there was no difference in shape retention and sintering density during degreasing by other binders. Then, there was no problem with respect to the releasability of the molded body except for the binder d.

The binders O and R were slightly blistered during degreasing and deformed during degreasing. Also,
The binder P was deformed at the time of degreasing, and the binder Q was poor in releasability and it was difficult to remove the molded body from the mold.
The edge portion of the binder R was easily broken when the molded body was taken out from the mold.

Further, the binders o, p, q, and r showed almost the same tendency as the binders O, P, Q, and R. However, the binder q is releasability in comparison with the binder Q is improved, binder q is crystalline whereas this cause is used polyamide resin component binder Q has a C ₄₄ diacid material This is because the adhesiveness is improved by using nylon 12 having a high particle size.

Further, when the carbonyl iron fine powder material is used as the metal powder material, each binder C, D,
As a result of degreasing in an N ₂ gas atmosphere using F, I, U, YY, c, e, and g, the binders F and YY have internal cracks,
The rate of generation of chips was high, and the carbon content of the sintered body was significantly changed by the difference in the final degreasing temperature. However, the binder U was free from the occurrence of internal cracks and the trouble related to the amount of carbon in the sintered body, and was superior in function as a lubricant to the binder F.

[0107] When with water solvent extraction degreasing binder YY, _{T 1} is the raw material _{C 36} diacid and the polyamide resin component average carbon number of 12.2 or respectively 9.6 or the between the aforementioned amide group It is inflated while extraction with water solvent to are adjusted, in order to C ₃₆ abruptly gasified moisture trapped in the molecule of the diacid during the degreasing by subsequent thermal decomposition Blisters and cracks occurred. In particular, the defects were T ₁ is significantly occur. But,
The mixture of C ₃₆ diacid and C ₄₄ diacid and a raw material, and 50% or more linear component of diacid, as described above, and 12.9 on the average number of carbon atoms between amide groups as a result In the binder ZZ using the polyamide resin component adjusted as described above, the occurrence of blistering and cracking as described above was substantially prevented. Also,
In the binder yy, remarkable blisters and cracks were not observed, and improvement could be achieved by the effect of ethylene bisstearic acid amide added as a lubricant. Here, the binder YY
And from a comparison with binder yy, it is possible also water solvent extraction degreasing with 12.2 on the average carbon number of the above, and the average carbon number is 9.6 or binder T ₁ is impossible to water solvent extraction degreasing For this reason, it is considered preferable to use a polyamide resin component having an average carbon number of 10 or more for degreasing with an aqueous solvent.

The binders A, F, G, H, J, M,
Regarding N, V, W, X, and Y, especially those subjected to an extraction treatment with a water solvent for 4 hours, no deformation was observed after the subsequent thermal decomposition degreasing, and defects such as blisters, cracks, and internal cracks were also observed. It was confirmed that it did not occur.

Further, binders a to c, e to g,
Binder c and binder e among m, v, w, and y have blisters and cracks in the same manner as binder YY.
This is because, as described above, the polyamide resin component has a high water absorption and a large amount of thermally unstable ethylenebislauric amide, so that the absorbed water rapidly gasifies. If the xylylene bis stearic acid amide coexists in the good urchin binder, it can be seen that degreasing method by water solvent extraction water of the polyamide resin component is significantly improved can be easily applied. When xylylenebisstearic acid amide is not added, the polyamide resin component needs to have sufficient water resistance. From the above results, the average carbon number between amide groups is at least 10 or more. Deemed necessary. From this point of view, a polyamide resin raw material obtained by copolymerizing nylon 12 as a polyamide resin raw material according to the present invention with ether, using C ₄₄ and C ₃₆ diacids as raw materials and positively using xylylenediamine and hexamethylenediamine. Are preferred.

In the above-described method for producing a sintered body only by thermal decomposition degreasing, the binder A
_{~L, YY, ZZ, T 1} , T 2 and a binder a~c,
Heat and knead at 140 ° C. using e to g, cool and pulverize, put the pulverized material in a stainless steel container to check the influence of absorption of moisture from the atmosphere, and cover the stainless steel container. Temperature around 25 ° C and humidity 80
% For more than 2 days. Next, the pulverized material left for two days was injection-molded under the same conditions into a coma-shaped molded body shown in FIG.

Binders A to L, ZZ, T ₂ , a, b,
The moldings using f and g could be molded without any trouble, but the moldings using binders YY, T ₁ , and e caused the molded body to be molded using a mold due to extreme strength deterioration due to moisture absorption. At the time of removal from the mold, cracks have already occurred in the part a and the parting line in FIG. 1 of the molded body, and the molded body can be taken out of the mold only in a state of being divided into several pieces, and a sound molded body can be obtained. Did not.

In this embodiment, N, N'-diacetylpiperazine, which is a secondary amine, toluylenediamine, which is a primary amine, and a benzene ring as an amide-based water-soluble substance are used as amine-based water-soluble substances. no acetamide, acetaminophenol having a benzene ring, C ₄₄
Manufactured by Uniqema as diacid Pripol 1004, C ₃₆ Uniqema Ltd. Pripol 1008,1013 as diacid, azelaic acid as aliphatic dicarboxylic acid, ethylenediamine and xylylenediamine as-diamine, N as perfuming Zoku径bisamide as a compatibilizer, N'-xylylenebisstearic acid amide (Slipax PXS manufactured by Nippon Kasei), N, N'-ethylenebislauric amide (Slipax L manufactured by Nippon Kasei) and N, N'-
Ethylene bisstearic acid amide (Sulfax E manufactured by Nippon Kasei Co., Ltd.) was used, but similar results can be obtained by using the other substances described above.

As described above, it is clear that the present invention can be variously modified. Such modifications do not depart from the spirit and scope of the invention, and all such modifications and changes which are obvious to a person skilled in the art are intended to be covered by the appended claims.

[Brief description of the drawings]

FIG. 1 is a side view showing a metal powder injection molded product injection molded in this embodiment.

FIG. 2 is a side view showing a test piece injection-molded in the present embodiment.

FIG. 3 is a side view showing a state of an internal crack generated in the test piece in FIG.

FIG. 4 is a graph showing the relationship between the amount of residual binder and the extraction time of a molded body that has been subjected to a binder extraction and drying treatment with an aqueous solution.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Katsuyoshi Saito 36, Shimogamo-Kifune-cho, Sakyo-ku, Kyoto-shi (72) Inventor Yutaka Ono 140-3, Kubojima, Oaza, Kumagaya-shi, Saitama Pref. 3-64401 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B22F 3/02, 3/10

Claims (33)

(57) [Claims] 1. A polyamide resin raw material comprising: (a) 40 to 70% by weight of an amide-based water-soluble substance and / or an amine-based water-soluble substance; and (b) a polyamide resin having an average of 8 or more carbon atoms between amide groups. 25 to 60% by weight of a polyamide resin component obtained by mixing an aromatic bisamide (ii) as a compatibilizer having an average of 8 or more carbon atoms sandwiched between amide groups with respect to i) to approximately equal weight%. A binder for metal powder injection molding, comprising: Wherein said polyamide resin material is a _{C 36 diacid, C 44} diacid or a mixture thereof _{C 36} diacid and _{C 44} diacids, aliphatic dicarboxylic acids having 6-10 carbon, xylylene The binder for metal powder injection molding according to claim 1, wherein the binder is obtained by copolycondensing a rangeamine with ethylenediamine and / or hexamethylenediamine. 3. The polyamide resin raw material has an average molecular weight of 20,000 or more.
3. The binder for metal powder injection molding according to 1.). 4. The polyamide resin component is sandwiched between amide groups with respect to a polyamide resin raw material (i) having an average of 8 or more carbon atoms between amide groups mainly composed of nylon 11 and nylon 12. Aromatic bisamide (i) as a compatibilizer having an average of 8 or more carbon atoms
2. The binder for metal powder injection molding according to claim 1, wherein i) is mixed to approximately equal weight%. 5. The polyamide resin raw material has an average molecular weight of 13,000 or more.
3. The binder for metal powder injection molding according to 1.). 6. The aromatic bisamide is a mixture of one or more of xylylene bisstearic acid amide, N, N′-distearyl isophthalic acid amide and N, N′-distearyl terephthalic acid amide. The binder for metal powder injection molding according to any one of claims 1 to 5, characterized in that: 7. The amide-based water-soluble substance is a substance having an amide group, the amine-based water-soluble substance is a substance having an amino group, and a melting point of the amide-based water-soluble substance and the amine-based water-soluble substance. 6. The composition for metal powder injection molding according to claim 1, wherein one or more of the compounds having a boiling point of 190 ° C. or lower and a boiling point of 175 ° C. or higher are mixed. Binder. 8. The binder for metal powder injection molding according to claim 1, further comprising 0 to 15% by weight of a lubricant. 9. The metal powder injection molding binder according to claim 8, wherein the lubricant is mainly composed of a fatty acid amide. Wherein said _{C 36} diacid and _{C 44} diacid,
4. The binder for metal powder injection molding according to claim 2, wherein the binder is a polymerized fatty acid obtained by bimolecular polymerization of an unsaturated fatty acid. 11. The binder for metal powder injection molding according to claim 4, wherein the polyamide resin component has a melting point or a glass transition temperature adjusted to about 190 ° C. or less. 12. A polyamide resin raw material comprising (a) 40 to 70% by weight of an amide-based water-soluble substance and / or an amine-based water-soluble substance, and (b) a polyamide resin having an average of 10 or more carbon atoms between amide groups. A binder for metal powder injection molding, comprising a substantially 25 to 60% by weight of a polyamide resin component. Wherein said polyamide resin material is a _{C 36 diacid, C 44} diacid or a mixture thereof _{C 36} diacid and _{C 44} diacids, aliphatic dicarboxylic acids having 6-10 carbon, xylylene 13. The binder for metal powder injection molding according to claim 12, wherein the binder is obtained by copolycondensing a rangeamine with ethylenediamine and / or hexamethylenediamine. 14. The polyamide resin raw material has an average molecular weight of 20,000 or more.
4. The binder for metal powder injection molding according to 3. 15. The polyamide resin component is substantially composed of a polyamide resin raw material having an average of 10 or more carbon atoms interposed between amide groups mainly composed of nylon 11 and nylon 12. The binder for metal powder injection molding according to claim 12, wherein 16. The polyamide resin raw material has an average molecular weight of 13,000 or more.
6. The binder for metal powder injection molding according to 5. 17. The amide-based water-soluble substance is a substance having an amide group, the amine-based water-soluble substance is a substance having an amino group, and a melting point of the amide-based water-soluble substance and the amine-based water-soluble substance. 17. A metal powder injection molding according to any one of claims 12 to 16, characterized in that one or more of those having a boiling point of 190 ° C or lower and a boiling point of 175 ° C or higher are mixed. Binder. 18. The binder for metal powder injection molding according to claim 12, further comprising 0 to 15% by weight of a lubricant. 19. The binder for metal powder injection molding according to claim 18, wherein the lubricant is mainly composed of a fatty acid amide. 20. The method of claim 19, wherein C ₃₆ acids and C ₄₄ diacid, metal powder injection molding binder according to claim 13 or 14, characterized in that a polymerized fatty acid obtained by bimolecular polymerization of unsaturated fatty acids . 21. The binder for metal powder injection molding according to claim 15, wherein the polyamide resin component has a melting point or a glass transition temperature adjusted to about 190 ° C. or lower. 22. (a) 40 to 70% by weight of an amide-based water-soluble substance and / or an amine-based water-soluble substance, and (b) a polyamide resin raw material having an average of 8 or more carbon atoms between amide groups. 25 to 60% by weight of a polyamide resin component obtained by mixing an aromatic bisamide (ii) as a compatibilizer having an average of 8 or more carbon atoms sandwiched between amide groups with respect to i) to approximately equal weight%. First, the amide-based water-soluble substance and / or the amine-based water-soluble substance are eluted from a molded body obtained by injection molding using a metal powder injection-molding binder containing:
Next, the polyamide resin component is removed by heating. 23. The polyamide resin material is a _{C 36 diacid, C 44} diacid or a mixture thereof _{C 36} diacid and _{C 44} diacids, aliphatic dicarboxylic acids having 6-10 carbon, xylylene 23. The degreasing method according to claim 22, wherein the degreasing method is obtained by copolycondensing a rangeamine with ethylenediamine and / or hexamethylenediamine. 24. The polyamide resin component is sandwiched between amide groups with respect to a polyamide resin raw material (i) having an average of 8 or more carbon atoms between amide groups mainly composed of nylon 11 and nylon 12. Aromatic bisamide (i) as a compatibilizer having an average of 8 or more carbon atoms
23. The degreasing method according to claim 22, wherein i) is mixed up to approximately equal weight%. 25. The aromatic bisamide is a mixture of one or more of xylylene bis stearamide, N, N′-distearyl isophthalamide and N, N′-distearyl terephthalamide. The degreasing method according to any one of claims 22 to 24, wherein the method is performed. 26. The amide-based water-soluble substance is a substance having an amide group, the amine-based water-soluble substance is a substance having an amino group, and a melting point of the amide-based water-soluble substance and the amine-based water-soluble substance. 25. The degreasing method according to any one of claims 22 to 24, wherein a mixture of at least 190 ° C and a boiling point of 175 ° C or more is used. 27. The degreasing method according to claim 22, further comprising 0 to 15% by weight of a lubricant. 28. (a) 40 to 70% by weight of an amide-based water-soluble substance and / or an amine-based water-soluble substance, and (b) a polyamide resin raw material having an average of 10 or more carbon atoms interposed between amide groups. First, the amide-based water-soluble substance and / or the amide-based water-soluble substance is formed from a molded product obtained by injection molding using a metal powder injection molding binder containing 25 to 60% by weight of a substantially polyamide resin component using a water-based solvent.
Alternatively, a degreasing method characterized by eluting an amine-based water-soluble substance and then removing the polyamide resin component by heating. 29. The polyamide resin material is a _{C 36 diacid, C 44} diacid or a mixture thereof _{C 36} diacid and _{C 44} diacids, aliphatic dicarboxylic acids having 6-10 carbon, xylylene 29. The degreasing method according to claim 28, wherein the degreasing method is obtained by copolycondensing a diamine with ethylenediamine and / or hexamethylenediamine. 30. The polyamide resin component is substantially composed of a polyamide resin raw material having an average of 10 or more carbon atoms sandwiched between amide groups mainly composed of nylon 11 and nylon 12. The degreasing method according to claim 28, wherein 31. The amide-based water-soluble substance is a substance having an amide group, the amine-based water-soluble substance is a substance having an amino group, and a melting point of the amide-based water-soluble substance and the amine-based water-soluble substance. 31. The degreasing method according to any one of claims 28 to 30, wherein a mixture of at least 190 ° C and a boiling point of 175 ° C or more is used. 32. The degreasing method according to claim 28, further comprising 0 to 15% by weight of a lubricant. 33. A metal powder injection-molded product obtained by injection-molding a metal powder material using the metal powder injection-molding binder according to claim 1 or 12.