JPS6196002A - Easily sinterable composite - Google Patents

Abstract

PURPOSE:To obtain the titled composite superior in moldability and capable of being burnt sufficiently in a short time, by specifying a compsn. ratio composed of surface treated sintering material powder and syndiotactic 1.l2 -polybutadien and organic oxide. CONSTITUTION:The composite is composed of sintering material consisting of metal and/or inorganic compound having 0.1-500mu average particle diameter, and >=600 deg.C m.p., syndiotactic 1.2 - polybutadiene having 0.1-30 g/10min melt index and 10-45% crystallinity, and organic peroxide, said sintering material is 50-95 wt.% compsn. ratio to total quantity of this and syndiotactic 1.2 -polybutadiene, organic peroxide is 0.1-10 wt. part compsn. ratio to said total quantity; 100 wt. part, and surface of sintering material is treated with 0.1-10 wt. part of higher fatty acid and/or metal salt to said sintering material; 100 wt. part.

Description

DETAILED DESCRIPTION OF THE INVENTION [I] Object of the Invention The present invention provides a method of combining a powdery metal and/or inorganic compound with a high melting point whose surface has been treated with a higher fatty acid and/or a metal salt of the fatty acid, and a resin. After cross-wiring and shaping, it can be easily shaped when degreased and sintered.
and relates to a sinterable composition. For more details, (
A), from metals and/or inorganic compounds whose surfaces are treated with higher fatty acids and/or metal salts of said fatty acids, whose average particle size is essentially 0.1 to 500 microns, and whose melting point is 600°C or higher. (B) syndiotactic 1,2-polybutadiene and (C)
The present invention relates to an easily sinterable composition made of an organic peroxide, and aims to provide a composition that has excellent moldability and can significantly shorten the degreasing time.

[II] Background of the invention (prior art) Recently, various sintered bodies using ceramics or metal powder have been used as electronic materials,
It has been widely used in fields such as electrical materials and automobile materials. However, the currently widely used methods of manufacturing powder for molding using a spray dryer and then manufacturing molded products for sintering using a rubber press are extremely complicated processes and have extremely low yields. Not only is this problematic, but it also has the disadvantage that a molded product with a complicated shape cannot be obtained. In order to solve these problems, methods have been proposed in which a composition obtained by kneading ceramic or metal powder and various thermoplastic resins is formed into various shapes as an injection molding material (for example, Kosho 51-29170.

JP-A-55-113510 and JP-A-55-113511).

However, when such a thermoplastic resin is used as a matrix, it is necessary to slow down the temperature increase rate for degreasing (calcination), and it is extremely difficult to control the temperature increase pattern with precision. There has been a problem in that so-called "voids" occur in molded products.In order to improve these 151 problems.

For example, JP-A-5S-1+3J? No. s, 55-114
As seen in No. 524 and No. 57-17488,
Attempts to solve the problem by making various improvements in the degreasing process have been proposed, but there is no pretreatment such as debinding by solvent extraction, and there is no void generation.
Moreover, it was difficult to perform degreasing in a short period of time.

[m] Structure of the Invention In view of the above, the present inventors have conducted various searches to obtain a composition that solves these problems.

(A) A sinterable substance consisting essentially of a metal and/or inorganic compound having an average particle size of 061 to 500 microns and a melting point of 600°C or higher, (B) 1.2-
Contains at least 85% bond and has a melt index (
According to JIS K-7210, the temperature is 150°C and the load is 2. Measured under the conditions of l[ikg, hereinafter referred to as "liver
) is 0.1 to 30 g/10 minutes.

It is a composition consisting of syndiotactic 1,2-polybutadiene and (C) an organic peroxide, and has a crystallinity of 10 to 45%, and the sinterable substance and syndiotactic 1,2-polybutadiene are The composition ratio of the sinterable material in the total amount is 50 to 95% by weight, and the composition ratio of the organic harsh material to 1 part mm 100'R of the sinterable material and syndiotactic 1,2-polybutadiene. is 0.1 to 1 offi, and the sinterable material is 0.1 to 10 parts with respect to the sinterable material of the loo double star part.
Parts by weight of higher fatty acids and/or gold Ii of said fatty acids!
An easily sinterable composition whose surface is treated with salt has solved the above problems, has excellent formability using injection molding methods, and can significantly shorten degreasing time. The present invention was achieved by discovering that it is a composition that has the following characteristics.

[IV] Effects of the Invention The composition obtained by the present invention exhibits the following effects, including the properties of the molded product during molding and after sintering.

(1) Excellent kneading properties and no secondary agglomeration.

(2) Due to good flow characteristics, it is easy to shape even molded products with complex shapes.

(3) No lipoids or cracks occur in the molded product during degreasing.

(When manufacturing the 0 composition, there is very little contamination of impurities from the screw, barrel, nozzle, etc. of the molding machine during kneading, and therefore, after sintering, the sintered product is not colored by impurities.

The most remarkable effect of the composition of the present invention is that it is possible to increase the temperature increase rate during degreasing (calcination), and as a result, the degreasing time can be shortened. In other words, in the conventional method of degreasing a molded article of a composition, the binder in the molded article was always slowly removed at a rate of temperature increase of 1 to b from room temperature.In contrast, when degreasing the composition of the present invention, It is also possible to increase the heating rate to 10 to so'c/hour.

Therefore, in the conventional method, 5 to 1O
However, when using the composition of the present invention,
One to two days is sufficient, and not only can productivity be greatly improved, but it is also advantageous in terms of fuel costs.

Furthermore, the easily sinterable composition obtained by the present invention has extremely good fluidity properties, and when this composition is manufactured by the melt mixing method, it is also possible to manufacture a molded article from the composition by the molding method described below. Even when.

It can be carried out in the same manner as in the case of general olefin polymers or compositions thereof.

The composition obtained according to the present invention can be used in a wide variety of fields by sintering it to exhibit one or more effects. Typical uses are shown below.

(1) Electronic and electrical parts such as various bearings, core rods, casings, motor shafts, insulators, circuit boards, etc. (2) Industrial parts such as various plates, large industrial parts such as turbine plates, etc. (3) Cylinder liners, turbochargers, etc. Automotive parts (4) Precision S equipment parts such as gears and shafts [V]
Detailed description of the invention (A) Sinterable substance The sinterable substance of the present invention has a melting point of 1 and a decomposition temperature or sublimation point of 6.
00°C or higher, preferably 1,000°C or higher, particularly preferably 1,400°C or higher. If a metal or inorganic compound with a decomposition temperature or sublimation point of less than 600°C is used as a sinterable substance, harmful deformation and blistering will occur during degreasing (sintering). Moreover, the average particle size is 0.1 to 500 microns. This average particle size varies depending on the type of sinterable material.

In the case of metals, it is usually 1 to 500 microns.

1 to 300 microns is preferred, especially 1 to 200 microns.
Micron is optimal. If a metal with an average particle size of less than 1 micron is used, kneading is difficult.

On the other hand, if you use metal with a diameter exceeding 500 microns.

The mechanical properties of the molded product obtained by sintering deteriorate.

In the case of inorganic compounds, the thickness is generally 0.1 to 200 microns, preferably 01 to 150 microns, and particularly preferably 0.1 to 100 microns. Average particle size is 0.
If an inorganic compound with a diameter of less than 1 micron is used, it is difficult to uniformly disperse the inorganic compound during kneading to produce one composition.

On the other hand, if an inorganic compound with a diameter exceeding 200 microns is used,
When sintering a molded product of the composition, the shape retention becomes poor, the density after sintering decreases, and the mechanical strength of the sintered body decreases.

Typical examples of metals used as sinterable materials in the present invention include total silicon, high-speed steel (e.g., pure iron),
Examples include superalloys such as titanium, tungsten, and boron, zirconium, and titanium. In addition, typical examples of inorganic compounds include alumina, ik silicon IL4. silicon nitride,
Zirconia, cordierite, tungsten carbide,
Examples include aluminum nitride. Furthermore, as a sintering aid, boron, beryllium, carbon, yttrium oxide, cerium oxide, magnesium oxide, lithium oxide, etc. are added in an appropriate small amount (generally, at most 20 parts by weight per 100 parts by weight of the inorganic compound). It may be added.

(B) Syndiotactic 1.2-Polybutadiene Also 1 Non-diotactic 1 used in the present invention
, 2-polybutadiene is obtained by polymerizing butadiene. This syndiotactic 1
．． MFI of 2-polybutadiene is 0.1-30g/10
minutes, preferably 0.2-30 g/10 minutes, particularly preferably 0.5-20 g/10 minutes.

Syndiotactic 1 with MFI less than 0.1 g/10 min
When 22-polybutadiene is used, it not only has poor dispersibility with the sinterable substance when producing the composition, but also
On the other hand, if syndiotactic 1,2-polybutadiene exceeding 30 g/10 minutes is used, the green body properties of the resulting composition will not be satisfactory, and the crystallinity will be poor. The syndiotactic 1.2-polybutadiene of the present invention has the following characteristics: 1. 10 to 45% is preferred, and 15 to 40% is particularly preferred.
2=Contains at least 85% (particularly 30% or more) of bonds, and is different from cis-1,4-polybutadiene and trans-1,4-polybutadiene. i.e. 1
Syndiotactic 1.2- used in the present invention
Polybutadiene is used as ordinary rubber1.
It is a polymer that is different in substance from 4-polybutadiene and has the characteristics of plastic and rubber, and is generally widely used as a stretch film.

Further, telechelic liquid polybutadiene having an allyl (alDl) type partial hydroxyl group is different from the syndiotactic 1,2-polybutadiene of the present invention, and even if it is used, a good composition cannot be obtained.

(C) Organic peroxide Furthermore, the organic peroxide used in the present invention is generally used as an initiator in radical polymerization and as a crosslinking agent for polymers. The decomposition temperature (temperature at which the half-life is 1 minute) is generally 110 to 300°C, preferably 110 to 250°C, and especially 120 to 230°C.6 Decomposition temperature If an organic peroxide with a temperature of less than 110°C is used, it is not only difficult to handle, but also the effect of using it will not be observed, so it is not desirable.On the other hand, if an organic peroxide with a temperature of more than 300°C is used, Typical examples of the most suitable organic peroxides are
．． 1~bis-tertiary-butylper″oxy-3,3,5
- Ketone peroxides such as trimethylcyclohexane, alkyl peroxides such as dicumyl peroxide, 2,5-dimethyl-2,5-di(tertiary-methylperoxy)-hexyne-3 and 2,5-dimethylhexane. Mention may be made of hydroperoxides such as -2,5-hydroperoxide, diacyl peroxides such as benzoyl peroxide, and peroxy esters such as 2,5-dimethyl-2,5-dibenzoylperoxyhexane.

In the present invention, among these organic peroxides, liquid ones can also be used as they are. In addition, a solid substance can be used by dissolving it in a solvent, or by dispersing it in a synthetic oil such as mineral oil, animal or vegetable oil, or silicone oil, or making it into a paste. In this case, the amount of organic peroxide contained in the oil is usually 5 to 70% by weight.

(0) Surface treatment of sinterable material The surface of the sinterable material used in the present invention is treated with a higher fatty acid and/or a metal salt of the fatty acid described below.

This higher fatty acid generally has 6 to 20 carbon atoms, preferably 8 to 20 carbon atoms, and particularly preferably 10 to 20 carbon atoms.

When treating the surface of a sinterable material using a fatty acid with a carbon number of 5 or less or its metal salt, it is not only difficult to handle, but also increases its solubility in water, making it difficult to form due to the influence of moisture. Sexuality decreases.

In addition, the metal of the metal salt is Ia of the periodic table of elements.

Metals of the +1a, Ilb and Hrb groups are preferred, especially lithium, magnesium, calcium, strontium, barium, zinc and aluminum.

Representative examples of higher fatty acids used in this treatment include lauric acid, ricinoleic acid, palmitic acid, stearic acid and oleic acid. Metal salts of higher fatty acids include metal salts of these higher fatty acids. Typical examples include lithium stearate, magnesium stearate, calcium stearate, strontium stearate, barium stearate, zinc stearate, and aluminum stearate. , magnesium palmitate, calcium laurate, barium laurate, zinc laurate, barium ricinoleate and zinc cinoleate.

The treatment ratio of the higher fatty acid and the metal salt of this fatty acid to 100 i9 parts of the sinterable material is 0.1~! a weight q parts, 0.1 to 7
．． 1 part of OQ is desirable, and 0.1 to 6.0 parts by weight is particularly optimal. The treatment ratio of higher fatty acids and their metal salts to 100 weight φ parts of sinterable material is o as a total amount,
The resulting composition has poor fluidity and poor moldability.On the other hand, if more than 1Qj7 (i part is processed), the moldability is not good, and the calcination (degreasing) described later ) Sometimes blisters and voids occur, making it impossible to obtain a good sintered product.

In order to treat the surface of the sinterable material with the higher fatty acid and/or the metal salt of the fatty acid, it is necessary that the higher fatty acid and/or the metal salt thereof undergo some kind of chemical reaction on the surface of the sinterable material. be. On the other hand, if the sinterable substance and the higher fatty acid and/or its metal salt are simply mixed without heating, this treatment will be insufficient, and the sinterable substance will be mixed during melt-kneading with 1,2-polybutadiene. Secondary agglomeration is observed, leading to defects in the final sintered product.

There are various methods for surface treatment.

As a typical method, sinterability and higher fatty acids and/or metal salts thereof may be simultaneously added and mixed in a mixer such as a Henschel mixer that has been preheated to 80 to 110°C. The sinterable substance and the higher fat # and/or its metal salt may be placed and heated to 80 to 170°C. Furthermore, the sinterable substance may be placed in advance in a mixer heated to 90 to 120°C. The higher fatty acid and/or its metal salt may be added while maintaining this temperature and stirring.

(Left below) (E) Composition ratio (composition ratio) In the easily sinterable composition obtained by the present invention, the total amount of the sinterable material whose surface has been treated as described above and syndiotactic 1,2-polybutadiene. The composition ratio of the sinterable material therein is 5G-95%, and 80-15%.
The surface-treated sinterable material and the syndiotactic 1
．． If the composition ratio of the sinterable material to the total amount with 2-polybutadiene is less than 50ffi%, the physical properties of the green body (
Although the strength and shape retention are good, the density after removing the binder is low and sintering is difficult. On the other hand, if it exceeds 95 double star%, the crosstalk, moldability and dispersibility of the composition are not only bad.

It is difficult to produce a uniform composition, and even if a uniform composition is obtained, a good green body cannot be obtained.

In addition, the addition ratio (composition ratio) of organic peroxide to the total amount of 10021 parts of the sinterable material whose surface has been treated and syndiotactic 1,2-polybutadiene is 0.1.
~8.0 heavy FM part is desirable, especially 0.1~5.0
The total amount of surface-treated sinterable material and syndiotactic 1,2-polybutadiene is preferably 10 parts by weight.
The addition ratio of organic peroxide to 0 parts by weight is 0.1ff
If the amount is less than i part, not only will degreasing take a long time, but the resulting sintered product will have blisters, cracks, etc. On the other hand, if it is added in excess of 10 parts by weight, the moldability of the composition decreases, making it difficult to produce a sintered product having a complicated shape.

(F) Composition production, molding method, etc. In producing the composition of the present invention, stabilizers against oxygen and heat, and metal deterioration inhibitors commonly used in the field of syndiotactic 1,2-polybutadiene. A lubricant may also be added.

The composition obtained by the present invention can also be produced by drag blending using a mixer such as a Henschel mixer, which is commonly used in the field of syndiotactic 1,2-polybutadiene, or by dry blending using a mixer such as a Henschel mixer, which is commonly used in the field of syndiotactic 1,2-polybutadiene. , Niegoo.

It can also be obtained by melt rQ kneading using a mixer such as a roll mill and a single screw extruder. At this time, a homogeneous composition can be obtained by triblending in advance and melting and kneading the resulting mixture. In this case, the mixture is generally melt-kneaded and then molded into pellets, which are then used in the molding described later. The composition thus obtained can be processed by injection molding, which is commonly practiced in the field of syndiotactic 1,2-polybutadiene.
It is molded into a sheet shape or a molded article having various shapes by a molding method such as an extrusion molding method or a press molding method.

It should be noted that the melting point is higher than the melting point of the syndiotactic 1,2-polybutadiene used in both melt-kneading and molding, but it is necessary to carry out the process within a range that essentially does not cause crosslinking. From these reasons, 100-160℃
It may be carried out within a temperature range of

When calcining a molded article formed in the above manner,
As the temperature rises, the organic binder (1,2-
polybutanoene) is almost completely cured to form a tertiary i, 117
It will form a 1st eye structure. For this reason, the heating rate for almost completely cured molded products is 10 to 100 liters per hour.
Even if the temperature is raised at a fast rate such as ℃, it is possible to obtain a molded product without blisters or cracks. (In order to achieve this, the temperature must be raised slowly as described below.) Even if the molded product of the composition of the present invention is heated at a fast rate as described above, it is unlikely that blisters or cracks will occur. This is thought to be because the 1,2-polybutadiene in Composition No. 5 was completely cured, and no deformation due to melting or 1-ite movement occurred.

This calcination can be carried out using a degreasing (calcination) furnace such as an electric furnace or a gas furnace using an inert gas (e.g.

This calcination can be carried out in an atmosphere of argon, helium, nitrogen), and the organic binder (mainly 1.
This is a process in which 2-polybutadiene and its cured product are completely decomposed and volatilized. The end of calcination is when the organic binder in the molded product is completely removed, and as a guideline, use a thermobalance [Basic Chemistry Selection 7 "Instrumental Analysis"]
(Shokabou.

Published September 20, 1975) Pages 308 to 317
The purpose is to find the decomposition end temperature of the thermal decomposition curve obtained by [see page].

In the commonly performed calcination, the polymer does not harden because the molded product does not contain a hardening agent such as an organic peroxide, and does not have a three-dimensional network structure.

Therefore, if calcination is carried out too quickly, many problems will occur, such as harmful deformation of the molded product such as blisters and cracks, and the generation of voids inside. For this reason, the temperature increase rate during calcination is slowed down (usually.

However, in the calcination of the present invention, as mentioned above, the heating rate is 0.1°C to 10°C per hour. Even if the molded product is not subjected to the above-mentioned harmful deformation or internal voids, it is extremely advantageous in terms of fuel cost and productivity.

The molded product calcined in this way (molded product substantially free of organic binder) may be left as it is or −μ cooled (
to produce the sintered product, which is the final object of the present invention, by raising the temperature under the same atmosphere or reduced pressure as in the case of calcination using the same type of furnace used for calcination. I can do it. The temperature can be raised at a faster rate than during calcination because the molded product does not contain an organic binder. Generally, the heating rate is 150° C. or less per hour, and the temperature is raised to a temperature slightly lower than the melting point of the sinterable material used.

[71] Examples and Comparative Examples Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, in the examples and comparative examples, the density is JIS K
-8758. Also, the 1 bending strength is A
Measured according to Scho MD-790.

Further, the apparent melt viscosity was measured using a Koka type flow tester with a nozzle having a diameter of 1 m+s and a length of 5H at 125° C. and a load of 30 kg.
For degreasing, the temperature was raised to 900° C. over 45 hours at 20° C./hour in a nitrogen atmosphere using an electric furnace (inner volume 2000 cc). In addition, sintering is done using the same electric furnace as above.
In an inert gas (argon) atmosphere or under vacuum (10'
) to the sintering temperature at a rate of 90°C/hour.

The types and physical properties of the ethylene fibers, sinterable substances, and organic peroxides used in Examples and Comparative Examples are shown below.

[(A) Syndiotactic 1,2-polybutadiene] As syndiotactic 1,2-polybutadiene, Ah! , is 3. 1,2-polybutadiene [density 0.930 g/Cm' as microstructure
．． 2-binding amount SO%, hereinafter referred to as rRB(1)] and M, 1. 1,2-polybutadiene [density 0.9087 m゛, microstructure: 1.2
- The binding amount was 92%, hereinafter referred to as "RB(2)J".

[(B) Sinterable substance]

As a sinterable substance, alumina with an average particle size of 1.0 microns (manufactured by Showa Light Metal Co., Ltd., trade name AL-45-A,
Melting point 2050℃, 1.0 wt% addition) -
→ Carbon silicon with an average particle size of 0.6 microns (manufactured by Showa Denko, product name DOA-2S, boron 0.5%)
(Contains 3.0% heavy phase carbon) and pure iron with an average particle size of 41H chrome (manufactured by Showa Denko K.K.).

(trade name: Atomiron Fine Para'/-44MR) was used.

[(C) Organic peroxide]

As an organic peroxide, 2,5-dimethyl-2,5-di(
Tertiary-butylperoxy)hexyne-3 (decomposition temperature 193°C) was used.

[(D) Higher fatty acids and metal salts 1 As higher fatty acids and metal salts, stearic acid, magnesium stearate (hereinafter referred to as "stearic acid 11 g J
), lithium stearate (hereinafter referred to as ``stearate L1''), barium stearate (hereinafter referred to as ``BaJ stearate''), zinc stearate (hereinafter referred to as ``ZnJ stearate''), aluminum stearate, (
Hereinafter referred to as "stearic acid AIJ") and bugnesium laurate (hereinafter referred to as "Mg laurate") were used.

Examples 1 to 12, Comparative Examples 1 to 4 A mixture of the above sinterable substance and higher fatty acids or metal salts of higher fatty acids whose types are shown in Table 1 (per 100 parts by weight of the sinterable substance) (proportions shown in Table 1) were mixed for 5 minutes using a Henschel mixer preheated to 80°C.Then, the mixed system was allowed to cool to approximately room temperature (25°C).

The above-mentioned syndiotactic 1.2-polybutadiene etchant 1 surface-treated sinterable material (types are shown in Table 1) and organic peroxide were mixed in advance in a Henschel mixer in the amounts shown in Table 1. Tri-blending was performed for 2 minutes each using the following. Each of the obtained mixtures was heated using a vented twin-screw extruder (diameter 35a+m) for 150 m
Pellets were produced while kneading at a temperature of °C.

Each pellet was put into an injection molding machine (resin temperature 130
Samples for bending test measurements and disks for sintering (
A thickness of 3m++ and a diameter of 22.5+n) was manufactured.

In this way, the sintering disk was degreased using a degreasing furnace under the above conditions. Although sintering may be performed immediately after the completion of degreasing, the degreased product was allowed to cool in order to observe the appearance of the obtained degreased product. The appearance of the degreased products is shown in Table 2. Each degreased product thus obtained was treated under the conditions described above (in Example 2, under an argon atmosphere.

In other Examples and Comparative Examples, each sintered product was produced by sintering (in vacuum) (sintering temperatures are shown in Table 2). The appearance of the objects is shown in Table 2.

(Hereinafter, blank spaces) Although the composition obtained in Comparative Example 1 was injection molded, a molded product with a good surface could not be obtained. Further, the composition obtained in Comparative Example 2 and higher fatty acid or its metal 1! ! A composition using a sintered material that is not treated has a melt viscosity about 3 times higher than that of the easily sinterable composition obtained in the present invention, and both of them have a long period of time (3
During molding (for more than 3 months), impurities were mixed in from the screw die of the extruder. Furthermore, in Comparative Example 3, an attempt was made to melt and mix the mixture obtained by triblending, but #! It was impossible to practice.

From the results of the above Examples and Comparative Examples, it is clear that the easily sinterable composition obtained by the present invention not only has excellent mechanical strength, but also can be calcined in a relatively short time. It is clear that a good molded product (calcined product) with no voids or cracks was obtained in 45 hours, and the final product, the sintered product, also had a good appearance.

Claims (1)

[Scope of Claims] (A) A sinterable material consisting essentially of a metal and/or an inorganic compound having an average particle size of 0.1 to 500 microns and a melting point of 600°C or higher; (B) 1 .2 - Contains at least 85% bonds and has a melt index of 0.1
~30g/10min, and crystallinity is 10~45%
A composition consisting of syndiotactic 1,2-polybutadiene and (C) an organic peroxide, wherein the sinterable material accounts for the total amount of the sinterable material and the syndiotactic 1,2-polybutadiene. The composition ratio is 50 to 95% by weight, and the composition ratio of the organic peroxide to 100 parts by weight of the total amount of the sinterable material and syndiotactic 1,2-polybutadiene is 0.
．． 1 to 10 parts by weight, and the sinterable material is 100 parts by weight.
1. An easily sinterable composition whose surface is treated with 0.1 to 10 parts by weight of a higher fatty acid and/or a metal salt of the fatty acid based on 0.1 to 10 parts by weight of a sinterable material.