Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/22—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip
  • B22F3/225—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip by injection molding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/10—Sintering only
  • B22F3/1017—Multiple heating or additional steps
  • B22F3/1021—Removal of binder or filler
  • B22F3/1025—Removal of binder or filler not by heating only
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy

Definitions

• the present invention relates to a degreasing method, a degreased body obtained thereby, and a sintered body.
• the present invention relates to a degreasing method for degreasing the organic binder from a molded product obtained by mixing a powder and an organic binder and injection molding, a degreased body obtained by the degreasing method, and sintering the degreased body. It relates to a sintered body obtained by the above method.
• injection molding is performed in which a binder is mixed with a metal powder material so as to impart pressure moldability to form a compact, and then the binder is formed from the compact. It is manufactured by sequentially performing degreasing to remove, and sintering of a degreased molded body, so-called degreased body.
• This metal powder injection molding method has an advantage that, for example, a more complicated shape can be molded at a time and less post-processing is required, as compared with, for example, a metal powder molding method by press molding.
• the powder injection molding technology uses a larger amount of binder to impart hydrostatic pressure moldability than the ordinary powder metallurgy method.
• phenomena such as shape loss, rubbing, and cracking of the molded body tend to occur.
• it is necessary to use a binder in the degreasing process. Removal must proceed slowly, and Depending on the shape and thickness of the body, it usually takes 2 to 3 days for the degreasing process. Such deformation, rubbing, and cracking are likely to occur. The fact that it takes a long time is an issue to be solved in powder injection molding technology.
• Japanese Patent Publication No. 61-48585 / 1988 discloses a gas inert to the injection molded article.
• a degreasing method in which air is blown in a turbulent state and a method in which a part of the binder component dissolved in the porous material is absorbed have been proposed.
• Japanese Patent Publication No. Sho 62-332282 A degreasing method has been proposed in which the pressure of the injection molded body is maintained at a pressure higher than the vapor pressure of a thermoplastic binder.
• thermoplastic binder composed of binder components having different melting points is used to gradually flow out of the molded article in a liquid state gradually by heating to form a porous absorbent. Absorption and removal of the binder from the injection molded body, resulting in blisters and cracks It is expected that binder removal will be accelerated while preventing the occurrence of debris.However, in actuality, it will be liquid when it is removed from the molded body, so it will not be able to withstand its own weight in the degreasing process and will lose its shape from the molded body.
• JP-A-7979 describes a water-soluble polymer such as polyethylene glycol, polypropylene glycol and polyvinyl alcohol, and a non-ice-soluble polymer such as polystyrene and polyethylene.
• polyethylene glycol as a water-soluble polymer
• polystyrene solvent-extracted with methylene chloride and a polymer heated and removed with a strength component.
• the water-soluble polymer After heating the molded body using a binder consisting of three components of ethylene to a temperature equal to or higher than the melting point of polyethylene glycol, the water-soluble polymer is preferentially extracted with ice solvent using water as the solvent.
• a method is disclosed in which a polystyrene polymer is solvent-extracted with methyl chloride, and the polyethylene as a strength component is removed from the molded body by heating.
• This method also requires solvent extraction, since the inclusion of large amounts of weakly polyethylene glycol leads to weakening of the compact.
• solvent extraction process involves two steps, and as a result, sufficient degreasing time is shortened
• organic solvents such as methylene chloride is inevitable, which is not desirable in terms of cost and safety of workers.
• poly (ethylene glycol) has the properties of a water-soluble binder, an aqueous solution in which poly (ethylene glycol) is dissolved at a high concentration shows high viscosity, and removal of poly (ethylene glycol) from the surface of the molded product Is not swift and does not occur uniformly on the entire surface of the molded body, so that dripping similar to sweating is likely to occur, and the risk of cracking and deformation due to subsequent heat degreasing is avoided. There is a problem that it is not possible.
• polyethylene glycol, polyethylene oxide, a water-soluble polymer that has been polymerized to a higher molecular weight is used.
• polyethylene glycol, polyethylene oxide, a water-soluble polymer that has been polymerized to a higher molecular weight is used.
• a binder component and after extracting some or all of the polyethylene oxide by water solvent extraction, most of the remaining polyethylene binder is removed by heating. A method for doing so is disclosed.
• thermoplastic polyethylene oxide is known to have high thermal instability. For example, when heating and kneading with metal powder (SUS430C) at 150, shear heat is generated during kneading.
• the water temperature at the time of ice solvent extraction must be set to a temperature of approximately 50 or less in order to prevent dripping similar to sweating. There is a problem that cannot be used enough.
• the mechanism of extraction is as follows: first, the water-soluble polymer on the surface of the molded body melts into ice and diffuses into water, and at the same time, the pores in which the eluted water-soluble polymer existed The ice enters the molded body as a passage, and then melts into newly infiltrated water from the molded body around the path of the void, and the water-soluble polymer that has melted out of the molded body It is explained that it will spread to.
• the rate of extraction of the water-soluble polymer depends on the elementary process 1 in which the movement and diffusion of the water-soluble polymer in the path of the molded body are rate-limiting, and the water-soluble polymer in the solvent on the surface of the molded body. This is discussed in terms of the relationship between the concentration and the concentration difference at a position far from the surface, and the elementary process 2 in which the diffusivity of the water-soluble polymer in the ice solvent is rate-determining.
• thioxide has excellent properties as a high-viscosity water-soluble binder.
• a 1% by weight aqueous solution shows properties such that it becomes completely gel-like at room temperature.
• a water solvent is sprayed on the molded body using a nozzle (Japanese Patent Application Laid-Open No. 2-182803).
• Drift ice of the used water solvent Japanese Patent Application Laid-Open No. 2-182804
• fluidization of the water solvent using ultrasonic waves Japanese Patent Application Laid-Open No. 2-182804
• thermoplastic binder when debinding is performed in the atmosphere, the thermal decomposition of the thermoplastic binder becomes more rapid than in the case of thermal degreasing in N 2 gas atmosphere, for example, at 200 or more. Although it is accelerated, it has been reported from the temperature range above 250 that the degreasing rate is reduced, which is considered to be due to the formation of residual carbon content. It was reported that cracks were more likely to occur in molded products I have. It is also reported that when using easily oxidizable metal powder, a new oxide is formed on the metal surface, and as a result, the molded product during degreasing expands and cracks are more likely to occur.
• Miura et al. Reported that it can be controlled by degreasing in a mixture of N 2 gas and high concentration H 2 gas.
• the cryogenic addition method is basically Unlike direct carbon with the carbon starting to remain in the defatted body by oxygen Since the amount of carbon is controlled by the following reaction, it is expected that the amount of residual carbon can be controlled more than by the hydrogenation method.
• an object of the present invention is to use an aqueous material that uses a stable binder for powder injection molding that does not swell or hydrolyze due to moisture and that suppresses the viscosity of an aqueous solution extracted using water as a solvent.
• a degreasing method is provided that includes a process that enables the extraction of the aqueous solvent even with simpler equipment, at lower cost and more quickly and even for the part shape. To provide.
• Still another object of the present invention is to provide a degreasing method using a binder for powder injection molding having excellent strength and toughness for improving product defects during injection molding and degreasing.
• Another object of the present invention is to provide a degreasing method capable of preventing the occurrence of defects during degreasing and controlling the amount of residual carbon in a sintered body by adjusting the amount of residual carbon during degreasing. It is to provide. Disclosure of the invention
• a degreasing method according to the present invention is directed to a degreasing method for degreasing the organic binder from a molded product obtained by mixing a powder and an organic binder and performing injection molding.
• the organic binder is composed of a water-soluble organic binder component and a water-insoluble thermoplastic resin, and the degreasing step is performed by using ice as a main component of the solvent to remove the organic binder from the organic binder in the molded body. It features an ice solvent extraction step for extracting one component of the water-soluble organic binder.
• the water-soluble organic binder component is preferably at least one substance selected from amide-based water-soluble compounds and amide- or amide-based water-soluble compounds.
• a polyamide resin is preferable.
• thermoplastic water-soluble polymer such as the above-mentioned polyethylene oxide is usually made of a polymer material having a high degree of polymerization so as to have a molecular weight of 50,000 to 500,000, so that the temperature above the melting point can be obtained. It is a thermoplastic polymer that exhibits sufficient viscosity even in the above.
• Viscosity or adhesiveness develops, resulting in a sharp decrease in the speed of movement of molecules in a highly viscous state, and a decrease in diffusivity because the molecules of the transfer units are polymers. Resulting in.
• the biggest factor causing the above-mentioned problems during aqueous solvent extraction is understood as a means for simultaneously satisfying the conditions of obtaining thermoplasticity and being water-soluble. It is.
• an amide-based and / or amide-based water-soluble polymer having a molecular weight of about 100 or less and having a non-thermoplastic molecular weight with a negligible degree of polymerization can be used.
• the use of the water-soluble compound having a polymerization degree that can be almost neglected eliminates depolymerization due to thermal decomposition during heating and kneading with the powder, so that a stable fluidity of the kneaded material and a stable Injection molding has been made possible, and the problem of reusability of raw materials such as runners and spools has been eliminated.
• the temperature of the ice solvent be high from the viewpoint of solid solubility and diffusibility in an aqueous solution.
• the molded body is preferably treated with water whose temperature has been adjusted to the melting point of the water-insoluble thermoplastic resin or the vitrification temperature or lower.
• the viscosity generally tends to decrease in the high viscosity range.
• the above-mentioned degreasing problem is solved by using an amide-based or amine-based water-soluble compound, and the melting point is 503 ⁇ 4 £
• an amide-based or amine-based water-soluble compound of the type described above the bubbling and boiling phenomena of hot water with a temperature of 50 or more can be used, and complex effects that cannot be achieved by general external stirring effects can be achieved. A uniform stirring effect can be achieved even for shaped products.
• gas is introduced into the water solvent from outside, and boiling is promoted by heating under reduced pressure atmosphere. The agitation by the effect and the known mechanical water flow and agitation techniques can be used together.
• the molded articles being extracted with the aqueous solvent are positively moved in the aqueous solvent, so that the aqueous solvent can be easily obtained.
• a reciprocating movement of the compact preferably in one direction and / or in a circular motion, for example, by placing the compact on a rotating plate While distinguishing the type of compact and the processing time, it was possible to take out the compact at any time, and it was possible to process multiple types of compacts with different extraction times continuously.
• the ice solvent fluidize from the opposite direction to the forward direction with respect to the rotation direction, the strength of the fluidization can be more uniformly controlled.
• the solvent temperature during the extraction of the ice solvent in the molded product should be set to a temperature below the melting point of the water-soluble compound, and then heated to a temperature below the melting point of the polyamide resin component as the extraction proceeds.
• Heat treatment in an inexpensive (commercially available) pressure vessel allows easy extraction of ice solvent at 100 or more. Not only can the fat time be reduced, but also the extraction costs can be further reduced. In this case, it is easy and efficient to lower the temperature of the ice solvent to about 100 by returning the pressure to atmospheric pressure. Since it can be operated, the molded body can be directly immersed by using an amide-based or amine-based water-soluble compound having a melting point of 100 t or more. I like it because it saves time.
• the amide-based water-soluble compound used in the present invention is a substance having an amide group
• the amine-based water-soluble compound is a substance having an amide group.
• One or more of these amide-based water-soluble compounds and amide-based water-soluble compounds have a melting point of 50 ° C or more and 190 or less and a boiling point of 175 ° C or more. It is preferable to mix them.
• the amide-based or amine-based water-soluble substance with a low melting point of less than 50% is used as the main component of the binder, the strength of the compact tends to deteriorate and the molding cycle lengthens. Considering this, it is more preferable that the melting point is 50 ° C or more. On the other hand, when the melting point exceeds 190 ° C, the fluidity of the binder tends to be impaired, and the injection moldability tends to be impaired. Also, if the boiling point is lower than 175, during the kneading of the powder material and the binder or during the injection molding, the binder is vaporized more selectively than the binder, which hinders the stability of the injection molding and the reuse of the return material. Tends to come easily. These water-soluble substances may be dissolved in 1 Q 0 cc of water (including the heated state) in an amount of 1 gr or more, but higher extraction efficiency can be obtained by dissolving 10 gr or more.
• the amide-based water-soluble substance is a substance having an amide group, and is classified into those having no benzene ring in the chemical structure and those having a benzene ring.
• Examples of those not having a benzene ring include acetamide, propionic amide, aloxane (monohydrate), ethyl urethan, ethylene urea, glycol amide, and heptane.
• Examples include trimethylurea and ethyl ethyl sulfamate.
• Examples of those having a benzene ring include, for example, nitrobenzamide (0), nitrobenzhydrazide (0), phenylsemicarbazide (1) (C)
• Amine-based water-soluble substances are substances having an amino group, and are obtained, for example, by dehydration-copolymerization of about 1 mol of hexahydropiperazine and about 2 mol of acetic acid by a conventional method.
• N N'-diacetylpiperazine, which is a second amine system, is used.
• aminodimethylylaniline ( ⁇ ), aminobilidin (3) (/?), And aminokirenolene (2) ( a) (NH 2 C s H B N), ⁇ Mi Roh Kino Les emission (3)
• the amide-based and amide-based water-soluble substances have an amide group and an amino group, they are compatible with the polyamide resin component constituting the binder.
• those having a melting point of 190 or less and a boiling point of 175 or more are preferable. If the melting point exceeds 190, the fluidity of the binder tends to be impaired, and the injection moldability tends to be impaired.
• the boiling point is lower than 175, during the kneading of the metal powder material and the binder or during the injection molding, the solvent is more selectively volatilized than in the binder, and the stability of the injection molding and the return are improved. This tends to hinder the reuse of timber.
• These water-soluble substances may be dissolved in 100 cc of water in an amount of 1 g or more, but a high extraction efficiency can be obtained when the water-soluble substance is dissolved in 100 g or more.
• the water-insoluble polyamide resin used in the aqueous solvent extraction is sandwiched between the amide groups with respect to the polyamide resin raw material having an average of 8 or more carbon atoms between the amide groups. It is preferable to use a mixture obtained by mixing an aromatic bisamide as a compatibilizer having an average of 8 or more carbon atoms in an amount of up to approximately equal weight%. As a result, it is possible to improve the compatibility with the amide-based and amide-based water-soluble compounds, improve the water absorption of the polyamide resin raw material itself, and prevent swelling during aqueous solvent extraction. it can.
• the water-insoluble polyamide resin used for the ice solvent extraction is obtained by mixing one or more of the polyamide resin raw materials having an average of 10 or more carbon atoms between the amide groups. You can also get it. By mainly using a linear chemical structure in this way, it is possible to improve the water absorption of the raw material of the polyamide resin itself and to prevent swelling during extraction with an ice solvent.
• the poly-A Mi de ⁇ raw material 1 C 3 6 diacids, C 4 4 diacid, or a mixture thereof C 3 6 diacid and C 4 4 diacid, 2 carbon number of 6 to 1 0 It is preferably obtained by copolycondensation of an aliphatic dicarboxylic acid with (3) xylylenediamine and (4) ethylenediamine and / or hexanemethylenediamine, in which case the average is obtained. It is preferable that the molecular weight be 20 0,000 or more.
• the polyamide resin raw material may be mainly composed of Nylon 11 and Nylon 12; in this case, the average molecular weight is 13, 00 00 £ ⁇ It is good to be on.
• the nylon 11 and the nylon 12 can be obtained by, for example, deicing and condensing ⁇ -amino-undecanoic acid and ⁇ -amino lauric acid.
• a polyamide resin raw material having an average of 8 or more carbon atoms between the amide groups mainly comprising nylon 11 and nylon 12 is nylon 11
• Nylon 12 contains other nylon components, such as Nylon 2, 36, Nylon 2, 44, Nylon 6, Nylon 6, 8 Nylon 6, 10 Nylon 6, 36, Nylon 6, 4 4 and Ethers and the like may be copolymerized.
• Nylon 12 includes Daicel A17709P and L1724K manufactured by Daicel.
• Nylon 12-ether copolymer is manufactured by Daicel.
• the water used in the ice solvent extraction step is preferably ice by shower or ice in a steam state.
• a heating decomposition removal step of heating decomposition removal of a binder remaining after extraction of the water-soluble organic compound in the ice solvent extraction step it is preferable to further include a heating decomposition removal step of heating decomposition removal of a binder remaining after extraction of the water-soluble organic compound in the ice solvent extraction step.
• a heating decomposition removal step a large amount of gas is generated when the water-insoluble polyamide-based resin component decomposes and evaporates, since many outgoing passages are formed in the molded body by extraction with the aqueous solvent. It is possible to prevent the occurrence of cracks. Therefore, the heating atmosphere in the subsequent thermal decomposition degreasing step can be performed in the air.
• the present invention provides:
• N 2 is also rather in the inert gas of the gas composition in the atmosphere such as A r
• the formation of an oxide film is prevented, and the lubricant and polyamide resin are vaporized in a state where the organic material has a large decomposition molecular weight unit.
• the occurrence of degreasing defects is reduced by suppressing the carbonization reaction.
• Et al is, that you can almost controlled by Sunda one gas by and this introducing a C 0 2 in water solvent by Nda concentration in low NYCO and and heating atmosphere relatively in the molded body after extraction from the subsequently formed features in the water solvent extraction directly in the sintering process to approximately 8 0 Q the following N 2 + C 0 a or is heated under normal pressure or reduced pressure of C 0 2, and subsequent temperature
• the degreasing time is further shortened.
• the composition of the organic binder used in the molded article, the amide-based water-soluble compound and Z or the amide-based water-soluble compound are 20 to 80% by weight, and the raw material of the polyamide resin is used. And 20 to 65% by weight of a poly or poly amide resin.
• the amount of the amide-based water-soluble compound and / or the amide-based water-soluble compound is as large as 20 to 80% by weight, degreasing with an aqueous solvent is a considerable part of the degreasing process. Time-consuming heat degreasing The ratio of degreasing is reduced, and the degreasing time can be shortened.
• the amount of the amide-based or amine-based water-soluble compound is less than 20% by weight with respect to all the binders, it can be removed in the next heating degreasing step and deformation can be prevented. And it takes a lot of time to extract the ice solvent. To achieve the substantial effect of shortening the total degreasing time and preventing the occurrence of degreasing defects in the next process, it is necessary to use 40% by weight or more. It is preferable that there is. Although it depends on the shape of the molded product, if it exceeds 80% by weight, it becomes difficult to remove the molded product from the mold from the viewpoint of deterioration of the molded product strength. Preferably, it is 45 to 60% by weight.
• the amide-based or amine-based water-soluble compound substantially the same effect can be obtained by using one of the above-mentioned substances or by using a mixture of two of them.
• liquid substances such as dimethylformamide and dimethylacetamide.
• these dimethylformamides and the like may cause the deterioration of the strength as a binder, and the shape of the applied product may be reduced. Create restrictions.
• the water-soluble compound component is 40 to 70% by weight
• the polyamide resin component is 25 to 50%. It is preferably 45% by weight.
• the extraction efficiency is better when the aqueous solvent temperature of the amide-based or amide-based water-soluble compound is heated from room temperature to the melting point of 50 or more, and preferably 70 to 1 By setting it to 0 or more, the aqueous solvent extraction temperature can be set high.
• the aqueous solvent extraction temperature can be set high.
• a stirring effect can be expected on all surfaces of the molded body, and as a result, rapid Thus, a uniform extraction effect can be expected.
• This effect means that it is possible to enhance the extractability over the conventional extraction temperature of polyethylene glycol and polyethylene oxide (50 or less), and for example, diacetyl pipera.
• a melting point of about 124 ° C is found from the thermal analysis of the binder, so that boiling water of approximately 100 ° C or more than 100 ° C and 120 ° C Increased solid solubility in aqueous solution by superheated steam under C £ l or heated ice under pressure, etc., and a remarkable stirring effect of the aqueous solution enable rapid extraction and shorter degreasing time.
• the temperature of the ice solvent is set to a temperature equal to or lower than the melting point of the water-soluble compound, and the molded body is immersed in the water solvent and then extracted from the surface.
• amide-based or amine-based water-soluble compound ice solution used in the present invention has low viscosity, heated steam is used instead of heated water. May be used.
• the next heating degreasing time can be shortened more effectively.
• et al is, rather also about 8 0 0 ° C-in had us in the following temperature range to N 2 is an inert gas by mixing C 0 2 gas atmosphere sintering process by heating under C 0 2 atmosphere It is possible to perform sintering in an atmosphere (eg, vacuum, reduction, inert, air) that matches the powder up to the subsequent sintering temperature, and heat degreasing as a pre-sintering process is possible. It is practically unnecessary, and the degreasing time can be further reduced.
• an atmosphere eg, vacuum, reduction, inert, air
• a lubricant it is preferable to contain 15% by weight or less of a lubricant.
• a lubricant a fatty acid amide mainly having a linear chemical structure and an N-substituted amide having no swelling property and a binder strength are preferable.
• Poly A mi de system by Nda used in the present invention C 4 4 diacid, C 3 6 diacid poly ⁇ Mi de resin having an average carbon number of 8 or more between A mi de groups in raw materials Or to make xylylene bisstearic acid amide, etc. compatible with polyamide resin mainly composed of nylon 11 and 12 and having an average carbon number between amide groups of 8 or more.
• polyamide resin mainly composed of nylon 11 and 12 and having an average carbon number between amide groups of 8 or more.
• the degreasing time can be significantly reduced as compared with the conventional thermal decomposition degreasing method, and parts having a shape that is easily deformed during degreasing, and thermal decomposition Internal defects that are likely to occur during degreasing heating are likely to occur (metallic materials, ceramics), parts, It can be easily applied to parts using metal materials with a large specific gravity, such as component parts, as well as large and thick parts.
• the polyamide resin component is used in an amount of 20% by weight or more based on the total amount of binder, but a metal powder material having a relatively large specific gravity (for example, iron, copper, nickel, tungsten steel).
• a metal powder material having a relatively large specific gravity for example, iron, copper, nickel, tungsten steel.
• the polyamide resin component is preferably used in an amount of 60% by weight or less based on the total amount of the binder.
• the content of the aromatic bisamide contained as a compatibilizer in the polyamide resin component can be up to 7 Q% by weight on a weight basis, but the content is already approximately equal to 1% by weight. Since it becomes hard and may be damaged during molding, it is preferable that the amount is less than approximately equal to% by weight.
• the degreased body according to the present invention is characterized in that it is obtained by degreasing according to the above-described degreasing method. Further, the sintered body according to the present invention is characterized in that it is obtained by sintering after degreasing by the above-described degreasing method.
• ADVANTAGE OF THE INVENTION According to this invention, generation
• FIGS. 1 to 12 are diagrams for explaining a specific embodiment of the present invention.
• Figure 1 is a cross-sectional view of the compact a
• Figure 2 is a cross-sectional view of the compact b.
• Figure 3 is a schematic diagram showing a constant temperature bath for water solvent extraction
• FIG. 4 is a graph showing the results of an investigation on the extractability of molded product a at 20.
• FIG. 5 is a graph showing the results of an investigation on the extractability of the molded body a at 70 ° C.
• Figure 6 is a diagram showing the water solvent extraction package of the compact b.
• FIG. 7 is a graph showing the results of an investigation on the extractability of molded article b at 70 t
• Fig. 8 is a graph showing the results of an investigation on the extractability of molded product a in boiling water
• FIG. 9 is a cross-sectional view showing a solvent tank capable of heating under reduced pressure and heating under pressure.
• FIG. 11 is a cross-sectional view showing an apparatus for moving a compact
• FIG. 12 is a view showing a compact c. BEST MODE FOR CARRYING OUT THE INVENTION
• a C 36 diacid (Yunikema Co. Pre pole 1 0 1 3), and Azera Lee phosphate, and ethylene-les Njia Mi down, mixed with equimolar amounts and xylene Re Re down di ⁇ Mi emissions,
• a polyamide resin component (2) having an average molecular weight of about 40,000 was obtained.
• the average number of carbon atoms between the amide groups of the polyamide resin component (2) is about 12.2.
• nylon 12 non-terelastomer copolymer PEBAX5533N01 manufactured by TORAY
• N, N'-diacetylbiperazine (melting point: 140 ° C).
• N, N'-ethylene bisstearic acid amide (with a melting point of about 144), N, N'-ethylene bislauric acid amide (with a melting point of about 157 t) ), N, N'-xylylene bisstearic acid amide (with a melting point of about 123), acetoamide (with a melting point of about 82), carbamide acid (with a melting point of 48 )
• the above is the raw material
• the mixture was melt-mixed at a mixing ratio of a weight ratio as shown in Table 1, cooled, and pulverized to obtain binders A to I.
• Binder J is described in US Pat.
• the binder K is a typical binder composition described in JP-A-2-110101.
• the polyethylene oxide used for the binder 1K is thermoplastic and is considered to be strong from the viewpoint of the strength of the molded product.
• PEO — 18 (Molecular weight: 400 to 500,000) manufactured by Iron and Steel Chemical Co., Ltd. is used. did.
• Fine powder of stainless steel (SUS430, average particle size: 10 micron) made by the water atomization process.
• the mixture was heated and kneaded at 150 at the same temperature, cooled, and pulverized to obtain a raw material for injection molding.
• Injection molding conditions are set injection temperature of 1 4 0 t, pressure approximately 7 0 0 kg / cm 2 condition, FIG.
• the weight of the molded body a is about 130 gr r Z pieces and the maximum thickness is 11 mm, which is extremely large as a part to which injection molding technology is applied.
• the compact b is a relatively thin product with a weight of 50 gr r Z pieces and a maximum thickness of 4 mm.
• FIG. 3 shows a schematic diagram of the equipment used in this extraction experiment.
• This equipment is a commercially-available thermostatic bath, and is equipped with a stirrer to equalize the temperature inside the bath.
• a hot air dryer at 70 ° C for 2 hours.
• the extraction rate of one component of the water-soluble binder was determined from the weight change before and after extraction 1 [(weight of extracted component% total binder weight of molded body) x 100], and ice solvent extraction Was investigated for speed. This result is shown in FIG.
• the extraction rate 1 exceeded 20% within the experimental time range of 16 hours, indicating that the extraction was performed fairly quickly.
• binder J which is a comparative material
• extractability was observed for binder 1K containing the same weight percent of poly (ethylene oxide).
• the extraction rate was clearly lower than that of the binder containing the amide-based and amide-based water-soluble compounds.
• the molded body extracted for 16 hours at 20 showed a slight tendency to swell, particularly in the mold parting line portion of the molded body.
• Fig. 5 shows the results of an investigation of the extractability of the water-soluble binder under the same gentle stirring conditions as described above, with the temperature of the aqueous solvent raised to 70 to enhance the extractability. .
• the binder K was disclosed in Japanese Patent Application Laid-Open No. H02-110101.
• the ice solvent temperature was set to 50, and the extraction test results under the same stirring conditions as before are shown in Fig. 5. It was confirmed that it would not occur. However, it was found that the tendency regarding swelling was the same, and that the degree became more remarkable as the temperature of the aqueous solvent increased.
• the ratio 2 [(weight% of water-soluble components of all binders in the extracted weight% Z compact) 100] was investigated.
• Figure 7 shows the results of this survey. From Fig. 7, more than half (55 to 60%) of the water-soluble compound was extracted in 1 hour of immersion time, and 90% of the total water-soluble compound component was extracted in about 3 hours. You can see that it is done. This indicates that even with the gentle stirring used, it can be uniformly extracted into deep holes such as the compact b. Also, the ice solvent extraction time 1 hour and was what the result of the degreased by heating to at 3 5 0 at a heating rate of min 3 by N 2 atmosphere heating and degreasing furnace described above, were all good.
• the compact In b By analogy with the results of heat degreasing of the compact a described above, the compact In b, it can be seen that the original purpose can be achieved by 30 minutes of extraction processing. In addition, considering that the time required for degreasing the compact b by the conventional heat degreasing method requires about 50 to 60 hours, this embodiment, which can be reduced to about 4 hours, It can be seen that it provides a special effect.
• blowing gas such as air into the solvent tank is an extremely impeaching effect of promoting the extraction. It is considered that the equipment is also compact in terms of equipment.
• the compact is placed on a circularly rotating disk, and the compact is moved in one direction and / or back and forth.
• the compact is moved in one direction and / or back and forth.
• binder C and carbonyl iron powder material (CS iron powder manufactured by BASF, average particle size: 5 micron)
• CS iron powder manufactured by BASF average particle size: 5 micron
• a molded product c having a shape as shown in FIG. 12 was molded under the conditions of an injection pressure of 660 kg / cm 2 .
• the molded product c of the binder C was subjected to ice solvent extraction at 100 ° C. for 1 hour, and then subjected to the following heat degreasing.
• the heating degreasing conditions are as follows.
• C 0 by mixing 2 to the N 2 shows that the residual carbon content in the sintered body is accurately controlled, the amount of carbon easily controlled degreased body upon heating and degreasing after ice solvent extraction This means that the control of the amount of carbon in the subsequent sintering process is almost unnecessary, and sintering in a vacuum state can be achieved with equipment that is inexpensive. In addition, it is clear that this technology can effectively cope with the adjustment of the residual carbon content due to the difference in the type of binder used.

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• 1996
  • 1996-10-03 JP JP8263222A patent/JPH10110201A/ja active Pending
• 1997
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  • 1997-09-04 DE DE19782035T patent/DE19782035T1/de active Pending
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