JPH04202604A - Composition for injection molding - Google Patents

Abstract

PURPOSE:To manufacture a metal sintered body of a complicated shape with excellent dimensional accuracy and product yield, at the time of subjecting the powder of metal or alloy to injection molding and sintering, by using a specified organic binder. CONSTITUTION:At the time of kneading the powder of iron, stainless steel or the like with a binder, subjecting this kneaded material to injection molding into a desired shape, thereafter executing low temp. heating, subjecting the molded part to debinder treatment and successively executing sintering at a high temp. to manufacture precision machine parts or the like, as a binder, a composition obtd. by mixing a mixture of, by weight, 5 to 70% low density polyethylene and 10 to 80% paraffinic wax with, as a lubricant, any of saturated alcohol, polyunsaturated fatty acid, fatty amide, saturated linear fatty acid and monounsaturated fatty acid in the range of 0.5 to 20% with the powder of metal or alloy in the ratio of, by volume, (30:70) to (70:30) is used. An injection molded part of a complicated shape is easily manufactured with excellent dimensional accuracy.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an injection molding composition, and specifically to an injection molding composition used when producing precision mechanical parts with complex shapes by injection molding powder of metal or alloy and then sintering it. relating to things.

[Conventional technology]

Conventionally, sintered products obtained by powder metallurgy have been produced based on a manufacturing method in which metal powder or alloy powder as a molding product is press-molded and sintered. Press molding using only metal powder or alloy powder has difficulty producing products with three-dimensionally complex shapes or thin-walled parts such as knife edges. Therefore, in an attempt to eliminate the drawbacks of the above method, an injection molding composition consisting of metal-like alloy powder and a binder was injection molded into a mold of a predetermined shape, and the resulting injection molded body was heated to remove the binder. A method of obtaining a sintered metal or alloy product by performing a sintering treatment after that is disclosed (for example, Japanese Patent Application Laid-Open No. 57-16103,
7-26105 etc.). When obtaining a sintered product from an injection molding composition made by mixing metal or alloy powder and a binder, (
1) Member fp: The sintered density of the product is high; (2) when injection molded products are used, there is little variation in stacking and dimensions of the final product; (3) the injection molded products have good binder removal properties;
(4) In injection molding of injection molding compositions, it is essential to reuse unnecessary parts other than the product, such as part of the sprue and part of the waste, and recycle it several times or more. It is required to have good recyclability and (5) good moldability of I4 between the injection molded article and the mold. In the method described in JP-A-57-] 61 () 3,
Since metal powder or alloy powder with an average particle size of 10 microns or less is used, products with high sintered density can be obtained.

Problem to be Solved by the Invention 1 However, the compositions for injection molding such as those disclosed in JP-A-57-16103 are the worst! It takes less than 1 minute in terms of product weight and size variations, amorphous removal properties, recyclability, and mold release properties. In other words, injection moldability, in other words, the highest! Variations in the weight and dimensions of the product may be due to poor fluidity of the injection molding composition during injection molding, poor filling into the mold, cracks in the molded product, damage when taking it out of the mold, etc.
There is a problem that it is difficult to perform molding stably. In addition, with regard to debinding properties, there are problems in that it takes a long time to complete debinding, a high processing temperature is required, and defects such as cranking, blistering, and deformation are likely to occur in the molded product. Regarding recycling, recycling causes decomposition, evaporation, or deterioration of the binder in the injection molding composition, which changes the injection moldability of the injection molding composition, which tends to reduce the dimensional accuracy of the final product. There's a problem. Furthermore, there is a problem in that improving recyclability and debinding properties deteriorates other properties. For example, after injection molding, the molded product is separated into part of the subru and part of the runner near the gate, but if the gate method is side gate or ring gate, part of the runner will remain on the product side. In this case, it is necessary to perform gate cutting as post-processing. This gate cut increases costs both in terms of product and recycling. Therefore, recently, the first
As shown in the figure, a single gate cant is performed smoothly and uses a pinpoint gate method that requires no post-processing. In the pinpoint gate method, for example, when molding the gear 10, the pinpoint gate part 12 and the runner part 14 are
Injection is carried out as shown by the arrow through the sprue portion 16, and the injection molding composition solidifies in these portions as well. However, this method has a problem in that it is sensitive to mold releasability. In other words, when this method is adopted, the runner part 14 becomes very long, and when taking out the molded object from the mold, if the releasability between the molded object and the mold (mainly iron-based material) is poor, the molded object must be taken out. Unfortunately, molding becomes impossible. Furthermore, in order to improve the binder removal property, for example, in JP-A-51-121150, a processing aid and pore forming agent is added. However, this processing aid and pore forming agent is 1
Since decomposition and evaporation occur in the range of 00 to 200°C, under operating conditions of a kneading temperature of 150°C and an injection temperature of 150°C, deterioration of the processing aid and pore forming agent occurs during the process. As a result, repeated recycling changes the fluidity of the composition during injection molding, and the weight and dimensions of the molded product filled into the mold also change with each repeated recycling, which in turn causes changes in the final product. The dimensional accuracy of a certain sintered body also changes, so that the dimensional variation of the whole group of sintered bodies becomes large. In addition, when a processing aid and pore forming agent is added, the releasability from the mold is poor, and as mentioned above, there is a problem that it cannot be used for molds with pinpoint gates that are sensitive to mold releasability. . Therefore, in injection molding of precision parts using metal and/or alloy powder as the raw material T4, the present invention significantly reduces fluctuations in weight and dimensions of injection molded bodies manufactured by recycling, and improves the final product (sintered body). An object of the present invention is to provide an injection molding composition with significantly improved dimensional accuracy. In addition, the present invention provides binder removal properties and mold release properties that have been difficult to achieve with conventional injection molding compositions in injection molding of precision parts made from metal and/or alloy powders. The purpose of the present invention is to provide an injection molding composition with excellent properties. [Means for Solving the Problems] As a result of intensive research, the present inventors found that, as a measure to solve the problem U mentioned above, low density polyethylene, paraffin wax and Using a binder consisting of lubricant 1, the lubricant is mixed with saturated alcohol,
We would like to find that the above problems can be solved by selecting from the group consisting of polyunsaturated fatty acids, fatty acid amides, saturated straight chain fatty acids and monounsaturated fatty acids. That is, the injection molding composition of the present invention is basically an injection molding composition consisting of a sintering powder and a binder, and the sintering powder is selected from the group consisting of metals and alloys. The binder consists of at least one type selected from the group consisting of saturated alcohol, polyunsaturated fatty acids, fatty acid amides, saturated straight chain fatty acids, and monounsaturated fatty acids, low density polyethylene, and paraffin wax. It consists of. Furthermore, in the present invention, by varying the blending ratio of the sintering powder and the binder, and by varying the blending ratio of the sintering powder, low-density polyethylene, and paraffin wax, a suitable injection molding composition can be obtained. That is, the injection molding composition of the present invention, in one form, consists of a sintering powder made of one or more selected from metals and alloys, and a binder. The binder contains 15 to 70% by weight of low density polyethylene, 10 to 80% by weight of paraffin wax, and 5 to 2% by weight of paraffin wax.
It contains 0% by weight of saturated alcohol, and the blending ratio or volume ratio of the sintering powder to the binder is in the range of 30:70 to 7:30. In another aspect, the injection molding composition of the present invention is a composition comprising a sintering powder made of one or more selected from metals and alloys and a binder,
The binder contains 10 to 7% by weight of low density polyethylene, 20 to 80% by weight of paraffin wax, and 5% by weight of paraffinic wax.
Contains ~40% by weight of polyunsaturated fatty acids, and the blending ratio or volume ratio of the sintering powder and the binder is 30:
It is within the range of 70 to 70:30. In another aspect, the injection molding composition of the present invention is a composition comprising a sintering powder made of one or more selected from metals and alloys and a binder, and the binder comprises: 20-60% by weight of low-density polyethylene, 20-80℃% by weight of paraffin wax and 0.5% by weight
~20.1 amount? . of fatty acid amide, and the blending ratio or volume ratio of the sintering powder and the binder is 30:70 to 65.
: Within the range of 35. In another embodiment, the injection molding composition of the present invention is a #11 composition comprising a sintering powder made of one or more selected from metals and alloys and a binder,
The binder contains 15-65% by weight of low-density polyethylene, 15-80% by weight of paraffin wax, and 0% by weight of paraffin wax.
, 5 to 10% by weight of saturated straight chain fatty acids, and the blending ratio or volume ratio of the sintering powder to the binder is in the range of 0 to 65:35. Furthermore, in another aspect, the injection molding composition of the present invention is a composition comprising a sintering powder made of one or more selected from metals and alloys and a binder, and the binder or ~70% by weight low density polyethylene, 2
Contains O-8O paraffin wax and 5 to 35 weight percent of monounsaturated fatty acids, and the blending ratio or volume ratio of the sintering powder to the binder is 30 Nia 0 to 7.
It is within the range of 0:30. [Function] In the present invention, moldability is controlled by determining factors that improve binder removal properties and mold release properties in injection molding in the composition and blending ratio of the injection molding composition. The sintering powder used in the present invention includes one or more of iron-based alloys such as iron and stainless steel, metals such as nickel and cobalt, and alloys containing these metals as main components. I can do it. Any known low-density polyethylene can be used, but low-density polyethylene with a fluidity of 100 to 300 g/10 minutes as measured by the method specified in JIS K7210 is suitable for injection molding and binder removal. It is particularly preferred because the strength and shape retention of the molded product at the initial stage of processing are excellent. If the flow rate of the low density polyethylene is less than 100 g/10 minutes, the pressure moldability will be relatively low. Also, the fluidity is 3
Even if it exceeds 00 g/10 minutes, the strength and shape retention of the injection molded product will be relatively low. Any known paraffin wax may be used, but JIS
Softening point measured by K 7206 50-9
Preferably, the temperature is 0°C. If the softening point of the paraffin wax is less than 50°C, the cycle time during injection molding will be longer, and it will easily soften, resulting in inconveniences such as poor handling during molding6. When the temperature exceeds 90℃,
Thermal decomposition point increases and binder removal properties decrease. The lubricant reduces the adhesive strength between the mold and the injection molding composition and improves the mold releasability, and also the sintering powder and binder (paraffin wax and polyethylene).
It acts as a lubricant between the two, significantly reducing the friction at the interface, reducing the torque during kneading, and improving the fluidity of the injection molding composition, resulting in stable injection molding operations. The proportion of lubricant used varies depending on each injection molding composition. The lubricant has a melting point of 50°C or less and a boiling point of 200°C or less.
If the melting point of the lubricant is higher than 50℃, the adhesive strength with the mold and the coefficient of friction can be reduced.
After injection molding, there is a risk of worsening the releasability from the mold when taking it out from the mold. Also, the boiling point of the lubricant is 20
If the temperature is less than 0°C, the lubricant will evaporate during the kneading and injection molding processes, the viscosity coefficient of the composition will vary, and as a result, the weight of the molded article will change significantly and the dimensional accuracy of the product will deteriorate. Among lubricants, saturated alcohol has a chemical structure of C, H, , +, OH, and commercially available products can be used as they are. Representative examples of saturated alcohols that can be used in the present invention include caprylic alcohol and caprylyl alcohol. Further, the polyunsaturated fatty acid has a chemical structure of C-82°+1CO2H, and a commercially available product can be used as is. Typical examples of polyunsaturated fatty acids include linoleic acid and lilunic acid. Furthermore, commercially available fatty acid amides can be used as they are. Representative examples of fatty acid amides include caprylic alcohol and caprylyl alcohol. Further, the saturated straight chain fatty acid has a chemical structure of C, H2, CO2H, and commercially available products can be used. Representative examples of saturated straight chain fatty acids include capric acid, caprylic acid, enanthic acid, caproic acid, pelargonic acid, tridecanoic acid, and the like. Further, the monounsaturated fatty acid has a chemical structure of C, H2, C02H, and a commercially available product can be used as is. Typical examples of monounsaturated fatty acids include Linderic acid,
tuzunic acid, myristoleic acid, seamarin, oleic acid,
Gondolaic acid, etc. can be mentioned. When injection molding the composition of the present invention, commonly used equipment and equipment can be used as they are, and the molded product is heated at a heating temperature of 80 to 200 inches, C1 injection pressure of 500 to 2
000 kg/cm2. The binder contained in the molded body is depintered in various atmospheres. The product rate of injection molded products is usually in the range of 25 to 85% by volume, so the remaining 75%
15% (mainly part of the sprue and part of the runner) is used again for injection molding and becomes a product at the same ratio as above, and the rest is recycled again 2 Such recycling is usually repeated several times 6 In addition, when removing the binder from precision molded products using the powder of the injection molding composition of the present invention, when processing powder that is easily oxidized, the powder that is difficult to oxidize should be treated in an inert scum or under a reducing atmosphere. When heating, heat at a heating rate of 12 to 30°C/h in the air or in an inert gas atmosphere to 25°C.
It is possible to carry out debinding by heating from 0 to 300°C. When manufacturing products using conventional injection molding compositions, it was necessary to perform high-temperature treatment at 400 to 550°C at a slow heating rate of 1 to 10°C/h. Then, at a heating rate of about 12 to 30°C/hr,
It is possible to advantageously complete the debinding treatment by heating at comparatively low temperatures of 300°C to 300°C. The reasons for limiting various component composition ranges and blending ratios in each aspect of the present invention will be explained below. Mode a2 in which saturated alcohol was added to the lubricant: The reason why the volume of the metal or alloy powder as the sintering powder was set to 30 to 70% is as follows. If the volume of the sintering powder is less than 30%, it will be difficult to ensure the fluidity of the composition when injection molding the composition, making injection molding impossible, and the sintering powder in the injection molded body will be less than 30% of the volume. The degree of filling of the sintered part becomes low, making it difficult to improve the density of the final sintered part. On the other hand, if the volume of the sintering powder exceeds 70%, the strength of the injection molded article will decrease or the fluidity of the composition will decrease, making injection molding difficult. As for the composition range of the binder, low density polyethylene is
The reason for containing 5 to 70% by weight is as follows. If the content of low density polyethylene is less than 15% by weight, the strength and shape retention of the injection molded article will be reduced, and although the time required for binder removal treatment will be shortened, cracks will easily occur on the surface of the molded article. On the other hand, low density polyethylene or 70
If it exceeds % by weight, the time required for debinding treatment becomes unnecessarily long. The reason for containing 10 to 80 2 g of paraffin wax is as follows. The weight of paraffin wax is 10! ζ that is less than the amount%
The fluidity of the composition is reduced, the injection moldability is insufficient, the debinding time becomes longer, and the debinding temperature becomes higher. On the other hand, if it exceeds 80% by weight, the strength and shape retention of the injection molded product will be insufficient, and the molded product will likely become impossible to handle. The reason for limiting the amount of saturated alcohol to 5 to 20 parts by weight is as follows. If the saturated alcohol content is less than 5% by weight, the releasability from the mold will be poor, making it unusable for pinpoint gate molds, and the torque during kneading will also increase, resulting in poor separation between metal powder and binder. When mixing certain paraffin waxes and polyethylene, it becomes very difficult to mix them uniformly. On the other hand, if it exceeds 20% by weight, the strength of the molded product decreases and the molded product becomes easily broken when taken out from the mold after injection molding, making injection molding very difficult. Embodiment in which polyunsaturated fatty acids were added to the lubricant: The reason why the volume of the metal or alloy powder as the sintering powder was set to 30 to 70% is as follows. If the volume of the sintering powder is less than 30%, it becomes difficult to ensure the fluidity of the composition when injection molding the composition, making injection molding impossible, and the sintering powder in the injection molded body becomes difficult to maintain. The degree of filling of the sintered part becomes low, making it difficult to improve the density of the final sintered part. On the other hand, if the volume of the sintering powder exceeds 70%, the strength of the injection molded article will decrease or the fluidity of the composition will decrease, making injection molding difficult. As for the composition range of the binder, low density polyethylene is
The reason for containing 0 to 70% by weight is as follows. If the content of low density polyethylene is less than 10% by weight, the strength and shape retention of the injection molded article will decrease, and although the time required for binder removal treatment will be shortened, cracks will easily occur on the surface of the molded article. On the other hand, low density polyethylene or 70
If 1% by weight is added, the time required for the binder removal process becomes unnecessarily long. The reason for containing 20 to 80% by weight of paraffin wax is as follows. If the weight of the paraffinic wax is less than 20% by weight, the fluidity of the composition will decrease, injection moldability will be insufficient, the debinding treatment time will become longer, and the debinding treatment temperature will also increase. On the other hand, if it exceeds 80% by weight, the strength and shape retention of the injection molded product will be insufficient, and the molded product will likely become impossible to handle. The reason for limiting the polyunsaturated fatty acid content to 5 to 40% by weight is as follows. If the polyunsaturated fatty acid content is less than 5% by weight, the releasability from the mold will be poor, and it cannot be used in a pinpoint gate mold. Furthermore, the torque during kneading will be large, and the metal powder and binder It is very difficult to mix paraffin wax and polyethylene evenly. On the other hand, if it exceeds 40% by weight, the strength of the molded article will decrease, and the molded article will easily break when taken out from the mold after injection molding, making injection molding very difficult. Embodiment in which fatty acid amide is added to the lubricant: The volume of metal or alloy powder as sintering powder is 35 to 7
The reason for setting it to 0% is as follows. If the volume of the sintering powder is less than 35%, it will be difficult to ensure the fluidity of the composition when injection molding the composition, making injection molding impossible, and the sintering powder in the injection molded body will be less than 35%. The density of the packed layer becomes low, making it difficult to improve the density of the final sintered part. On the other hand, if the volume of the sintering powder exceeds 70%, the strength of the injection molded article will decrease or the fluidity of the composition will decrease, making injection molding difficult. As for the composition range of the binder, low density polyethylene is
The reason for containing 0 to 60% by weight is as follows. If the content of low density polyethylene is less than 20% by weight, the strength and shape retention of the injection molded article will decrease, and although the time required for binder removal treatment will be shortened, cracks will easily occur on the surface of the molded article. Conversely, low density polyethylene is 60
If it exceeds % by weight, the time required for the binder removal treatment becomes unnecessarily long. The reason for containing 20 to 80% by weight of paraffin wax is as follows. If the content of the paraffin wax is less than 20% by weight, the fluidity of the composition will be reduced, the injection moldability will be insufficient, the time for debinding treatment will become longer, and the temperature for debinding treatment will also increase. On the other hand, if it exceeds 80% by weight, the strength and shape retention of the injection molded product will be insufficient, and the molded product will likely become impossible to handle. The reason for limiting the amount of fatty acid amide to 0.5 to 20% by weight is as follows. If the fatty acid amide content is less than 0.5% by weight, the mold releasability from the mold will be poor, and it cannot be used for pinpoint gate molds, and the torque at AM will be low. This makes it extremely difficult to uniformly mix the metal powder, paraffin wax as a binder, and polyethylene. On the other hand, if it exceeds 20% by weight, the strength of the molded article decreases and the molded article becomes easily broken when taken out from the mold after injection molding, making injection molding very difficult. Embodiment in which saturated straight chain fatty acids were added to the lubricant: The reason why the volume of the metal or alloy powder as the sintering powder was set to 30 to 65% is as follows. If the volume of the sintering powder is less than 30%, it becomes difficult to ensure the fluidity of the composition when injection molding the composition, making injection molding impossible, and the sintering powder in the injection molded body becomes difficult to maintain. The packing layer becomes low, making it difficult to improve the density of the final sintered part. On the other hand, if the volume of the sintering powder exceeds 65%, the strength of the injection molded article will decrease or the fluidity of the composition will decrease, making injection molding difficult. As for the composition range of the binder, low density polyethylene is
The reason for containing 5 to 65% by weight is as follows. If the content of low density polyethylene is less than 15% by weight, the strength and shape retention of the injection molded article will decrease, and although the time required for binder removal treatment will be shortened, cracks will easily occur on the surface of the molded article. On the other hand, low density polyethylene or 65
If the weight percentage is exceeded, the time required for the de-ingu treatment becomes unnecessarily long. The reason for containing 15 to 80% by weight of paraffin wax is as follows. If the weight of the paraffinic wax is less than 15% by weight, the fluidity of the composition will decrease, the injection moldability will be insufficient, the debinding treatment time will become long, and the debinding treatment temperature will also increase. On the other hand, if it exceeds 80% by weight, the strength and shape retention of the injection molded product will be insufficient, and the molded product will likely become impossible to handle. The reason for limiting the amount of saturated straight chain fatty acids to 0.5 to 10% by weight is as follows. If the content of saturated straight chain fatty acids is less than 0.5% by weight, the mold releasability from the mold will be poor and it cannot be used in pinpoint gate type molds.Furthermore, the torque during kneading will be large and the metal It is extremely difficult to mix the powder, the paraffin wax binder, and polyethylene evenly. On the other hand, if it exceeds 10% by weight, the strength of the molded product decreases and the molded product becomes easily broken when taken out from the mold after injection molding, making injection molding very difficult. Embodiment in which monounsaturated fatty acid was added to the lubricant: The reason why the volume of the metal or alloy powder as the sintering powder was set to 30 to 70% is as follows. If the volume of the sintering powder is less than 30%, it becomes difficult to ensure the fluidity of the composition when injection molding the composition, making injection molding impossible, and the sintering powder in the injection molded body becomes difficult to maintain. The filling ring becomes low, making it difficult to improve the density of the final sintered part. On the other hand, if the volume of the sintering powder exceeds 70%, the strength of the injection molded article will decrease or the fluidity of the composition will decrease, making injection molding difficult. As the composition range of the binder, low density polyethylene is
The reason for containing up to 70% by weight is as follows. If the content of low density polyethylene is less than 5% by weight, the strength and shape retention of the injection molded article will decrease, and although the time required for binder removal treatment will be shortened, cracks will easily occur on the surface of the molded article. On the other hand, if the content of low density polyethylene exceeds 70% by weight, the time required for the binder removal process becomes unnecessarily long. The reason for containing 20 to 80 fi amount % of paraffin wax is as follows. If the weight of the paraffinic wax is less than 20% by weight, the fluidity of the composition will decrease, the injection moldability will be insufficient, the debinding treatment time will become long, and the debinding treatment temperature will also increase. On the other hand, if it exceeds 80% by weight, the strength and shape retention of the injection molded product will be insufficient, and the molded product will likely become impossible to handle. The reason for limiting the monounsaturated fatty acid content to 5 to 35% by weight is as follows. If the monounsaturated fatty acid content is less than 5% by weight, the mold releasability from the mold will be poor, and it cannot be used for pinpoint gate type molds.Furthermore, the torque at the time of crosstalk will increase, and the metal powder and binder It is very difficult to mix paraffin wax and polyethylene uniformly. On the other hand, if it exceeds 35% by weight, the strength of the molded product decreases,
When the molded body is removed from the mold after injection molding, the molded body is easily destroyed, making injection molding very difficult.

【Example】

[Examples A1 to A7] Carbonyl iron powder with an average particle size of about 5 μm and an average particle size of about 5 μm
A mixed powder having a composition of 2% by weight of Ni-Fe is prepared by mixing N1 powder of 1.0 m, and this is mixed and kneaded by combining it with a saturated alcohol-containing pinter having the composition shown in Table 1. A sintered product having a gear shape of 20 mm, thickness 5 mm, and 18 teeth, and a plate test piece for measuring mechanical strength were manufactured. The mold is a pinpoint gate type mold, as shown in FIG. That is, a mold having a shape corresponding to the gear 10, the bin point gate portion 12, the runner portion 14, and the sprue portion 16 is used. Injection molding in this mold was performed at an injection speed of 100 m/sec. The mold releasability was evaluated by the mold releasability of the sprue portion 16 from the mold. The results are shown in Table 2 together with the injection moldability results. The low density polyethylene used was a fluidized bed of 200 g/10 minutes, and the paraffin wax had a softening point of 70°C. In addition, the weight and dimensions of the injection molded products were measured, and the average value of each of the 20 products was determined. The results are shown in Table 3 (weight) and Table 4 (
Dimensions) Recycle count 1. Furthermore, the injection molded product is heated in a nitrogen scum atmosphere to remove the binder from the molded product, and after the binder removal process is performed until the remaining amount of binder becomes 1% by weight or less of the molded product, the appearance of the unbindered product is observed. did. The results are shown in Table 5 along with the heating temperature and time for debinding. All the debinding products had a good appearance. Furthermore, these binder-removed pieces were sintered in a vacuum at 1250° C. for 1 hour. The dimensions of the obtained sintered body were measured. Table 7 shows the results of measuring the strength of the sintered crystal using a standard plate test piece from the "Powder Metallurgy Technology Association." The numerical values are the average values of five test values. Furthermore, injection molding, binder removal treatment, and sintering are performed in the same manner as in the injection molding, using the compositions such as the gel part 16 and the runner part 14 other than the molded body obtained during the injection molding as raw materials, It was measured. The dimensions and weight of the sintered bodies were measured over 4 cycles for 20 molded bodies shown in the number of recycles 2 to 4 in Tables 3 and 4, corresponding to the number of recycling times 1. The variation is shown in Table 6. From the above, in Examples A1 to A7, the variations in the weight and dimensions of the molded bodies and the dimensions of the sintered bodies are extremely small within the same cycle and between the number of times of recycling, and there is almost no change in the average value. It can be seen that the appearance is good. [Comparative Examples A1 to A2] Processing and measurement were carried out in the same manner as in Examples A1 to A7, except that the weight proportion of saturated alcohol was not within the range of the present invention. Tables 1 to 7 show the composition of the injection molding composition and the measurement results of the molded articles. [Conventional Examples A1 to A3] Processing and measurement were carried out in the same manner as Examples A1 to A7, except that an additive not within the scope of the present invention was included instead of saturated alcohol. Tables 1 to 7 show the composition of the injection molding composition and the measurement results of the molded articles. [Examples A8 to A12] The injection molding composition powder shown in Table 8 was used instead of the Ni-Fe powder used in Examples A1 to A7, and low density polyethylene 281! was added to the powder. jL amount %, paraffin wax 65% by weight and caprylic alcohol 7
Binder consisting of % by weight was mixed at a volume ratio of 66:34, injection molded products were obtained in the same manner as in Examples A1 to A7, and the binder was removed at 250°C in the same manner as in Examples A1 to A7. However, the appearance of the binder-removed products of Examples A8 to A12 was also good. Next, the binder-free integral parts of Examples A8 to A12 were sintered under the conditions shown in Table 8, and the mechanical strength was measured in the same manner as Examples A1 to A7. The results are shown in Table 8. [Conventional Examples A4 to A81 In order to compare with Examples A8 to AI2, only the sintering powders shown in Table 8 were used, and after compression molding by the usual powder metallurgy method, these molded bodies were compared with those shown in Table 8. Sintered under similar conditions,
The strength was measured in the same manner as in Examples A8 to A12. The results are shown in Table 9. From the above results, it can be seen that the composition of this example is particularly effective for injection molding. Examples 81 to B7] Carbonyl iron powder with an average particle size of about 5 μm and carbonyl iron powder with an average particle size of about 5 μm
m Ni powder was mixed to make a mixed powder having a composition of 2% by weight of Ni-Fe, and this was combined with a monounsaturated fatty acid-containing binder having the composition shown in Table 10, mixed and kneaded, and carried out. Processed and measured in the same manner as in Examples A1 to A7. The results are shown in Tables 10 to 16. [Comparative Examples 81-B2] Processing and measurement were performed in the same manner as in Examples 81-s7, except that the weight ratio of monounsaturated fatty acids was not within the range of the present invention. The formulation of the injection molding composition and the measurement results of the molded products are shown in Tables 1o to 16. [Conventional Examples 81 to B3] Injection molding compositions treated and measured in the same manner as Examples 81 to B7, except that additives not within the scope of the present invention were included instead of monounsaturated fatty acids. Tables 10 to 16 show the formulations and measurement results of the molded bodies. [Examples 88 to B12 Using the injection molding composition powder shown in Table 17 instead of the Nj-Fe powder used in Examples 81 to B7,
A binder consisting of 30% by weight of low-density polyethylene, 55% by weight of paraffin wax, and 15% by weight of oleic acid was mixed with the powder at a volume ratio of 66:34, and an injection molded article was prepared in the same manner as in Examples 81 to B7. get 250
When the binder removal process was carried out in the same manner as in Examples B1 to B7 in "C, the binder removal process in Examples 88 to B12 was also good. Next, the binder removal process in Examples 88 to B12 was performed as shown in Table 8. The mechanical strength was measured in the same manner as in Examples 81 to B7.The results are shown in Table 17. [Conventional Examples 84 to B8] In order to compare with Examples 88 to B12, Using only the sintering powders shown in Table 17, compression molding was carried out by the usual powder metallurgy method, and then these molded bodies were sintered under the same conditions as in Table 17, and the strength was increased in the same manner as in Examples 88 to B12. The results are shown in Table 18. From the above results, it can be seen that the composition of this example is particularly effective for injection molding. Carbonyl iron powder and average particle size of 5μ
Example A1 - Processed and measured in the same manner as A7. The results are shown in Tables 19 to 25. [Comparative Examples C1-C2] Processing and measurement were carried out in the same manner as in Examples C1-C7, except that the weight proportion of fatty acid amide was not within the range of the present invention. Tables 19 to 25 show the formulation of the injection molding composition and the measurement results of the molded products. [Conventional Examples C1 to C3] Processing and measurement were carried out in the same manner as Examples c1 to c7, except that an additive not within the scope of the present invention was included instead of fatty acid amide. Tables 19 to 25 show the formulation of the injection molding composition and the measurement results of the molded products. Examples C8 to CI2 Using the injection molding composition powder shown in Table 26 instead of the Ni-Fe powder used in Examples C1 to C7,
To the powder, 65% by volume of a binder consisting of 28% by weight of low density polyethylene, 65% by weight of paraffin wax and 10% by weight of linoleic acid amide was added. : 35 to obtain an injection molded article in the same manner as in Examples 01 to C7, and subjected to debinding treatment at 250°C in the same manner as in Examples 01 to C7. /<The appearance of the indider was also good. Next, the debinding products of Examples C8 to C12 were sintered under the conditions shown in Table 26, and the mechanical strength was measured on the same machines as Examples C1 to C7. The results are shown in Table 26. [Conventional Examples C4 to C8] In order to compare with Examples C8 to C1 and 2, only the sintering powders shown in Table 26 were used, and after compression molding by a normal powder metallurgy method, these molded bodies were Sintering was carried out under the same conditions as in Table 26, and the strength was measured in the same manner as in Examples C8 to C12. The results are shown in Table 27. From the above results, it can be seen that the composition of this example is particularly effective for injection molding. [Examples D1 to D7] ゛Carbonyl iron powder with a V average particle size of about 5 μm and an average particle size of 5
μm Ni powder is mixed to make a mixed powder having a composition of 2% by weight of Ni-Fe, and this is mixed in combination with a saturated straight chain fatty acid-containing binder having the composition shown in Table 28,
The mixture was kneaded and treated and measured in the same manner as in Examples A1 to A7. The results are shown in Tables 28 to 34. [Comparative Examples D1-D2] Processing and measurement were carried out in the same manner as Examples D1-D7, except that the weight proportion of fatty acid amide was not within the range of the present invention. Tables 28 to 34 show the formulation of the injection molding composition and the measurement results of the molded products. [Conventional Examples D1 to D31 Processing and measurement were carried out in the same manner as Examples D1 to D7, except that an additive not within the scope of the present invention was included instead of fatty acid amide. Tables 28 to 34 show the formulation of the injection molding composition and the measurement results of the molded products. [Examples D8 to D121 Using the injection molding composition powder shown in Table 35 instead of the Ni-Fe powder used in Examples D1 to D7,
A binder consisting of 30% by weight of low-density polyethylene, 65% by weight of paraffin wax, and 5% by weight of capric acid was mixed with the powder at a volume ratio of 60:40, and an injection molded article was prepared in the same manner as in Examples D1 to D7. get 250
When the binder removal process was performed on 'C in the same manner as in Examples D1 to D7, the appearance of the actual bar examples D8 to D12 when the binder was removed was also good. Next, the binder removal unit of Examples D8 to D1.2 was
Sintering was performed under the conditions shown in Table 5, and the mechanical strength was measured in the same manner as Examples D1 to D7. The results are shown in Table 35. [Conventional Examples D4 to D8] In order to compare with Examples D8 to DI2, only the sintering powders shown in Table 35 were used, and after compression molding by a normal powder metallurgy method, these molded bodies were molded according to Table 35. It was sintered under the same conditions as above, and the strength was measured in the same manner as in Examples D8 to DI2. The results are shown in Table 36. From the above results, it can be seen that the composition of this example is particularly effective for injection molding. [Examples E1 to E7] Carbonyl iron powder with an average particle size of about 5 μm and an average particle size of 5 μm
m Ni powder was mixed to make a mixed powder having a composition of 2% by weight of Ni-Fe, and this was combined with a polyunsaturated fatty acid-containing binder having the composition shown in Table 37, mixed and kneaded, and carried out. Processed and measured in the same manner as in Examples A1 to A7. The results are shown in Tables 37 to 43. [Comparative Examples E1 to E2] Processing and measurement were performed in the same manner as in Examples E1 to E7, except that the weight proportion of polyunsaturated fatty acids was not within the range of the present invention. Tables 37 to 43 show the formulation of the injection molding composition and the measurement results of the molded products. [Conventional Examples E1 to E3] Processing and measurement were carried out in the same manner as Examples E1 to E7, except that an additive not within the scope of the present invention was included instead of the polyunsaturated fatty acid. Tables 37 to 43 show the formulation of the injection molding composition and the measurement results of the molded products. [Examples E8 to E12] Using the injection molding composition powder shown in Table 44 instead of the Ni-Fe powder used in Examples E1 to E7,
A binder consisting of 30% by weight of low-density polyethylene, 68% by weight of paraffin-based one lath, and 81% by weight of linole FL was mixed into the powder at a volume ratio of 62:38, and an injection molded article was prepared in the same manner as in Examples E1 to E7. get, 2
When the binder removal treatment was carried out at 50° C. in the same manner as in Examples E1 to E7, the appearance of the binder removed products of Examples E8 to E12 was also good. Next, the binder-free integral parts of Examples E8 to E12 were sintered under the conditions shown in Table 44, and the mechanical strength was measured in the same manner as Examples E1 to E7. The results are shown in Table 44. [Conventional Examples E4 to E8] In order to compare with Examples E8 to E12, only the sintering powders shown in Table 44 were used, and after compression molding by the usual powder metallurgy method, these molded bodies were molded according to Table 45. It was sintered under the same conditions as above, and the strength was measured in the same manner as in Examples E8 to E12. The results are shown in Table 45. From the above results, it can be seen that the composition of this example is particularly effective for injection molding. [Examples F1 to F3] Carbonyl iron powder with an average particle size of about 5 μm and a uniform particle size of about 5 μm
A mixed powder having a composition of 2% by weight of Ni-Fe was prepared by mixing Ni powder of m to 2% by weight, and this was combined with a composite lubricant-containing binder having the composition shown in Table 46, and mixed and kneaded to obtain Example A1. - Moldability and mold releasability were tested in the same manner as A7. The results are shown in Table 47. [Conventional Examples F1 to F3] In order to compare with Examples F1 to F3, treatments and measurements were carried out in the same manner as Examples F1 to F3 using a binder containing carbowax and oil without containing a lubricant. The results are shown in Tables 46 to 47. From the above results, it can be seen that the composition of this example using a composite lubricant is also particularly effective for injection molding. Table 2 *: Comparative example, *Cloth: Poor molding strength. Table 5*: Comparative example Table 6: Sintered body dimensions (mm) Table 7*: Comparative example Table 11*: Comparative example, **: Weak molding strength. Table 14*: Comparative example Table 15: Sintered body dimensions (mm) Comparative example Table 16*: Comparative example Table 20: Comparative example, Zero density: Weak molding strength. Table 23*: Comparative Example Table 24: Sintered body dimensions (mm) *Comparative Example Table 25*: Comparative Example Table 29*: Comparative Example, Kine: Weak molding strength. Table 32*: Comparative example Table 33: Sintered body dimensions (mm) Comparative example Table 34: Comparative example Table 38*: Comparative example, *(: Weak forming strength. Table 41*: Comparative example Table 42: Dimensions of sintered body (mm) Table 43*: Comparative example Table 47*Negated part did not come off.

【Effect of the invention】

The present invention is configured as described above, and has 250~
By heating at a relatively low temperature of 300°C, the binder removal process can be carried out advantageously, and furthermore, the molding of the molded body and the mold can be carried out smoothly, improving the stability of injection molding. In addition, according to the present invention, it is possible to obtain a good injection molded body using the sintering powder of IL metal or base metal, and it can also be used for molds of the Bin Point Game 1 ~ method that do not require gate cutting. Moreover, it is possible to obtain a sintered body with no variation in the weight or size of the molded body by recycling, and also with extremely small dimensional variation.As a result, electronic parts, precision FR
It is possible to satisfy the dimensional accuracy required for machine parts, and in particular, for thin parts with complex shapes, it is possible to supply powder metallurgy products made by injection molding at low cost and in a stable condition, making it possible to supply powder metallurgy products in a stable condition at a low price. It is a great contribution to this.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing a kia immediately after being molded from an injection molding composition using a mold. In the figure, reference numbers indicate the following elements: 10...Gear, 12...Pinpoint gate part, I4...Part of runner, 16...Part of sprue.

Claims (6)

[Claims] (1) An injection molding composition basically consisting of a sintering powder and a binder, wherein the sintering powder is made of one or more selected from the group consisting of metals and alloys, and the binder is Injection molding comprising at least one lubricant selected from the group consisting of saturated alcohol, polyunsaturated fatty acids, fatty acid amides, saturated straight chain fatty acids, and monounsaturated fatty acids, low density polyethylene, and paraffin wax. Composition for use. (2) The binder contains 15 to 70% by weight of low-density polyethylene, 10 to 80% by weight of paraffin wax, and 5 to 20% by weight of saturated alcohol, and the blending ratio of the sintering powder and the binder is 30 in volume ratio
The composition for injection molding according to claim 1, characterized in that the ratio is within the range of :70 to 70:30. (3) The binder contains 10 to 70% by weight of low-density polyethylene, 20 to 80% by weight of paraffin wax, and 5 to 40% by weight of polyunsaturated fatty acids, and the sintering powder and the binder Mixing ratio is 30 by volume
2. The injection molding composition according to claim 1, wherein the ratio is within the range of :70 to 70:30. (4) The binder contains 20 to 60% by weight of low density polyethylene, 20 to 80% by weight of paraffin wax, and 0.5 to 20% by weight of fatty acid amide, and the sintering powder and the binder Mixing ratio is 3 by volume
The injection molding composition according to claim 1, characterized in that the ratio is within the range of 0:70 to 65:35. (5) The binder contains 15 to 65% by weight of low density polyethylene, 15 to 80% by weight of paraffin wax, and 0.5 to 10% by weight of saturated straight chain fatty acid, and the sintering powder and the binder 2. The injection molding composition according to claim 1, wherein the composition is blended in a volume ratio of 30:70 to 65:35. (6) The binder contains 5-70% by weight of low-density polyethylene, 20-80% by weight of paraffin wax, and 5-35% by weight of monounsaturated fatty acid, and the sintering powder and the binder are blended together. The ratio is 30 by volume:
The injection molding composition according to claim 1, characterized in that the ratio is in the range of 70 to 70:30.