JPS6362349B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an abrasive product in which the abrasive grains are bonded with a heat-resistant resin, which is pressure-molded from a specific compound containing at least a specific aromatic polyimide powder and abrasive grains. The present invention relates to a whetstone having a grain layer, particularly a whetstone in which an abrasive grain layer is provided on a wheel-shaped base, and a method for manufacturing the same. [Description of the Prior Art] Conventionally, for example, polyimide resin is produced using a compound consisting of a combination of abrasive grains such as diamond or cubic boronite (hereinafter sometimes abbreviated as CBN) and a specific polyimide resin. It is known to produce grinding wheels having an abrasive layer to which diamond or CBN abrasive grains are bonded. Currently, it is known that aromatic polyimide obtained from pyromellitic dianhydride and 4,4-diaminodiphenyl ether can be used as the polyimide resin that has the highest heat resistance and is currently used in the above-mentioned grindstone. It is being This known grinding wheel has an abrasive grain layer in which abrasive grains are bonded with aromatic polyimide resin, and the resin, which is the bonding agent, is exposed to the high heat generated during heavy grinding and at the same time is subjected to high mechanical stress. It withstands harsh conditions well, making it particularly suitable for areas requiring heavy grinding. However, although this known aromatic polyimide resin has very good heat resistance, it is insoluble and infusible, and has an extremely high secondary transition temperature, and the moldability of the abrasive grain layer is extremely poor. There are disadvantages in that it takes a long time and productivity is poor, and furthermore, the known polyimide resin bonded grindstones are not fully satisfactory in terms of grinding performance. In general, there are two ways to obtain a molded article such as an abrasive layer using aromatic polyimide resin as a binder. There are two methods: one is to mix polyimide powder which has been chemically processed as a binder, and the other is to mold it. When making a grinding wheel from a compound containing polyamic acid powder as a binder, the by-product of the condensation reaction (imidization) of the polymer is generated when the packed layer of the abrasive grains, binder, etc. is pressed and molded. The drawback is that it requires a long imidization process that involves the generation of biological water. When making a grinding wheel from a compound containing polyimide powder as a binder, the molding process is shortened because the imidization process, which requires long heating, is no longer required, but the pyromellitic acid-based aroma that was previously used is Group polyimide powder has a secondary transition temperature of approximately 400°C or higher, has virtually no thermal plastic deformability, thermal adhesiveness, etc., and has excellent affinity and adhesion with abrasive grains. In order to improve the performance of the grindstone, it is necessary to perform molding and sintering at extremely high temperatures and pressures for a considerable period of time, resulting in insufficient productivity. For example, in US Patent No. 3,385,684,
``Filling the compound into the mold → heating the filled layer to 270℃ and preforming with a pressure of 3150 to 3500 kg/cm <sup>2</sup> → complete imidization of the polymer at 300℃ in a vacuum oven for 16 hours. →In inert gas, 450℃, 30 minutes,
It describes a method for manufacturing a polyimide bonded grindstone that requires a complicated process of "free sintering to form an abrasive grain layer" at extremely high pressure, temperature, and for a long time. The specification of the issue states, ``Filling the compound into the mold → At room temperature, 428
The manufacturing method for polyimide bonded grindstones is described as follows: "Preform by applying pressure of Kg/cm ² → Heat to 450℃ under low pressure → Pressurize to 3870Kg/cm ² at 450℃ for 20 minutes to form an abrasive grain layer." has been done. However, the grindstones obtained by these methods are mainly exemplified using conventional pyromellitic acid-based aromatic polyimide as a binder, which is unsatisfactory because the forming process requires a long time at high temperature and pressure. However, the affinity and adhesion with abrasive grains and fillers were insufficient, and the formed abrasive grain layer did not necessarily exhibit satisfactory grinding performance (grinding rate). On the other hand, other heat-resistant resins such as benzophenonetetracarboxylic acid-based aromatic polyimide, polyamideimide resin, bismaleimide, triazine resin, and polybismaleimide resin have been used as heat-resistant resin binders with good moldability. It is known that it is used for forming grain layers, but compared to the above-mentioned pyromellitic acid-based aromatic polyimide resin, its heat resistance and mechanical properties at high temperatures are insufficient, and other heat-resistant resins mentioned above are Grinding wheels that use grinding wheels are only used in a limited number of applications where high temperatures do not occur during grinding. As a result of intensive research into a method for industrially manufacturing a grinding wheel with an excellent performance abrasive grain layer by bonding abrasive grains using a highly heat-resistant polyimide resin as a binder, the inventors found that By using biphenyltetracarboxylic acid-based aromatic polyimide, which has a secondary transition temperature of 250 to 380°C, as the grain binder, the abrasive layer can be easily formed, making it the most suitable manufacturing method for this type of grindstone. They discovered that it was possible to form an abrasive layer that improved industrial productivity at once, had excellent grinding (polishing) performance, and also had excellent heat resistance and mechanical strength, and completed this invention. . [Structure of the present invention] That is, the present invention comprises 100 parts by weight of abrasive grains, an aromatic tetracarboxylic acid component containing 50 mol% or more of biphenyltetracarboxylic acid or its acid dianhydride, and an aromatic diamine component. At least 20 to 80 parts by weight of an aromatic polyimide powder obtained by polymerizing and imidizing an aromatic polyimide whose polymer has a second-order transition temperature of 250 to 380°C is added to the blend. The present invention relates to a heat-resistant resin-bonded grindstone characterized by having a pressure-molded abrasive grain layer containing 5 to 50% by volume of abrasive grains, and further comprising the above-mentioned abrasive grains and aromatic polyimide. A heat-resistant method characterized by filling a mold with a mixture of the aromatic polyimide and pressurizing the mixture to 100 to 5000 kg/cm ² at a temperature higher than the secondary transition temperature of the aromatic polyimide to form an abrasive layer. This invention relates to a method for manufacturing a resin-bonded grindstone. The second-order transition temperature mentioned above is the second-order transition temperature measured by dynamic viscoelasticity measurement (for example, measured using a mechanical spectrometer manufactured by Rheometrics). [Operations and Effects of the Present Invention] The grinding wheel of the present invention is characterized in that the above-mentioned biphenyltetracarboxylic acid-based aromatic polyimide powder, which is used as a binder for the abrasive grains, is heated at a rate of 10°C/min. It exhibits sufficient heat resistance of 530℃ or higher, as measured by the temperature at which it loses 5% by weight, and maintains high mechanical strength even at high temperatures. Because it is excellent, the grinding wheel performance such as "the grinding ratio expressed as the ratio (B/A) of the polishing weight B of the material to be polished polished by the grinding wheel to the consumed weight A of the abrasive grain layer of the grinding wheel" is extremely stable. It is excellent. The manufacturing method of this invention allows the above-mentioned biphenyltetracarboxylic acid-based aromatic polyimide powder to have a relatively low and clear secondary transition temperature, as well as high heat resistance, adhesion and affinity with abrasive grains, etc. It is an extremely productive industrial method that simplifies the molding process and shortens the molding time because it has excellent powder moldability and good overall powder moldability. This is a method that can produce a grindstone having layers with good reproducibility. Moreover, in the manufacturing method of the present invention, the abrasive grain layer formed from the above-mentioned aromatic polyimide-containing compound can be formed on various grinding wheel bases (for example, wheel-shaped metal bases such as aluminum or steel, or epoxy resin, phenol, etc.). Since it can be directly bonded with a large bonding force to a wheel-shaped synthetic resin base such as resin, it can be bonded directly to a wheel-shaped synthetic resin base, so it can be used for grinding wheels that have an abrasive grain layer that is integrally bonded to the whetstone base, especially whetstones that are bonded to a wheel-shaped base. This is an epoch-making method that allows a grindstone with a grain layer to be manufactured all at once without using an adhesive layer or the like. Further, according to the method of the present invention, a grindstone having an abrasive grain layer of excellent performance can be easily formed by integrally joining a grindstone base having a complicated shape. [Example] Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a perspective view showing an example of the grindstone of the present invention, and FIG. 2 is a sectional view of the grindstone. For example, as shown in FIGS. 1 and 2, the heat-resistant resin-bonded grindstone of the present invention has an abrasive layer in which abrasive grains are bonded with an aromatic polyimide formed from a specific compound by pressure molding. One example is a grindstone 3 in which 1 is provided on a grindstone base 2. The aromatic polyimide powder used in this invention is an aromatic tetracarboxylic acid containing biphenyltetracarboxylic acid or its acid dianhydride in an amount of 50 mol% or more, preferably 60 mol% or more, and more preferably 80 to 100 mol%. component and an aromatic diamine component by polymerization and imidization in roughly equimolar amounts, the polymer has a second-order transition temperature of 250 to 380°C, preferably
It is an aromatic polyimide powder with a temperature of 260-350℃. For the aromatic polyimide mentioned above, the sample was heated at 10℃/
The temperature when the sample is reduced by 5% by weight is approximately
Any material may be used as long as it has a heat resistance of 530°C or higher, particularly about 540 to 600°C. The aromatic polyimide described above preferably has a logarithmic viscosity (measured at 50° C., concentration: 0.5 g/100 ml, solvent: parachlorophenol) of about 0.1 to 7, particularly about 0.3 to 5. Furthermore, the average particle size of the aromatic polyimide powder used in this invention is about 0.1 to 100 μm, particularly 0.5 to 100 μm.
The thickness is preferably about 50 μm. The aromatic tetracarboxylic acid component used in the production of the aromatic polyimide is biphenyltetracarboxylic acid or its acid dianhydride,
2,3,3',4'-biphenyltetracarboxylic acid or its acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid or its acid dianhydride, or mixtures thereof. In particular,
3,3',4,4'-biphenyltetracarboxylic acids are preferred, and other aromatic tetracarboxylic acid components that can be used in combination with the biphenyltetracarboxylic acid include pyromellitic acid,
Benzophenonetetracarboxylic acid, bis(3,4
-dicarboxyphenyl)methane, 2,2-bis(3,4-dicarboxyphenyl)propane, bis(3,4-dicarboxyphenyl)ether,
or their acid dianhydrides, or mixtures thereof. Examples of the aromatic diamines include 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylthioether, 4,4'-diaminodiphenylmethane, 3, 4'-diaminodiphenylmethane, 4,
Mention may be made of 4'-diaminodiphenylpropane, 4,4'-diaminobenzophenone, o-, m- or p-phenylenediamine, or mixtures thereof. In this invention, in particular, 3,3',4,4'-biphenyltetracarboxylic acid or its acid dianhydride, or 2,3,3',4'-biphenyltetracarboxylic acid or its acid dianhydride 60 mol% or more, especially 80~
An aromatic tetracarboxylic acid component containing 100 mol%, 4,4'-diaminodiphenyl ether,
A high molecular weight aromatic polyimide powder obtained by polymerizing approximately equimolar amounts of 3,4'-diaminodiphenyl ether with an aromatic diamine component containing about 50 mol% or more, especially 60 to 100 mol%. It is suitable for the moldability of compounds blended with abrasive grains. The heat-resistant resin-bonded grindstone of the present invention contains 100 parts by weight of abrasive grains and 20 to 20 parts by weight of the above-mentioned aromatic polyimide powder.
150 parts by weight, preferably 30-120 parts by weight, and if necessary 0-100 parts by weight of filler, especially 10-80 parts by weight.
Pressure molded from a uniformly blended powder mixture consisting of 5 to 50 parts by weight, and after molding, 5 to 50 parts of abrasive grains were added.
The abrasive grain layer containing the abrasive grains at a ratio of about 10% to 45% by volume is, for example, one that is directly formed integrally with a grindstone base (such as a wheel). The above-mentioned aromatic polyimide powder is heated at a temperature of about 50 to 150° C. before being blended with abrasive grains and a filler.
It is preferable to use it after drying for about 20 hours, especially about 0.5 to 10 hours. Examples of the abrasive grains include natural or artificial diamond, cubic boron nitride, etc., and the average particle size of the abrasive grains is approximately
It is preferably about 0.5 to 500 μm, particularly about 1 to 100 μm. The filler may be any known filler that is generally used in the manufacture of resin-bonded grindstones, such as graphite, SiO ₂ , SiC, Al ₂ O ₃ ,
FeO ₃ , Cu, Sn, or mixtures thereof, and the average particle size of the filler is approximately
It is preferably about 0.1 to 100 μm, particularly about 0.5 to 50 μm. In this invention, the abrasive grain layer is, as described above,
It is sufficient if the abrasive grains are contained in a ratio of 5 to 50% by volume, but in particular, the composition is abrasive grains: 5 to 50% by volume (particularly preferably 10 to 45% by volume), aromatic polyimide resin: 10 to 50% by volume. 90% by volume (particularly preferably 20-80% by volume), and filler: 0-70% by volume (particularly preferably 5-50% by weight). Furthermore, it is desirable that the volume ratio of the abrasive grains and the aromatic polyimide resin contained in the abrasive grain layer be within the range of 1:3 to 3:1 (particularly preferably 1:2 to 2:1). . In this invention, the maximum thickness of the abrasive grain layer is not particularly limited, but it is suitably about 0.1 to 20 mm, particularly about 0.5 to 10 mm. In the manufacturing method of this invention, a mixture in which abrasive grains, aromatic polyimide powder, and filler if necessary are uniformly mixed in the above-mentioned mixing ratio is filled into a suitable mold for forming a grindstone. and a temperature higher than the second-order transition temperature of the aromatic polyimide, preferably a temperature of 5 to 80°C higher than the second-order transition temperature, particularly a temperature of 10 to 60°C higher than the second-order transition temperature (e.g., about 300 to 450°C).
(preferably in the range of 100 to 5000 °C)
Kg/cm ² , preferably at a pressure of 500 to 4000 Kg/cm ² ,
Preferably about 0.5 to 10 minutes/mm (abrasive layer thickness)
, and finally removed from the press and cooled to form a pressure-molded abrasive layer to produce a grindstone with an abrasive layer in which the abrasive grains are bonded with aromatic polyimide. That's what I do. In the manufacturing method of the present invention, before the above-described pressure molding (main molding) of the abrasive grain layer is performed, the compound is filled into a mold for molding a grindstone, and the mixture is initially weighed between 0 and 2000 kg/kg.
cm ² , especially at a pressure of 0 to 1000 Kg/cm ³ and below the second-order transition temperature of the aromatic polyimide, e.g.
100-300°C, especially 150-280°C), and further heated at the heating temperature of about 500-5000°C.
Kg/ ^cm2 pressure, preferably about 0.5-10 minutes/mm
It is preferable to preform the compound by applying pressure for a time equal to (thickness of the abrasive grain layer), and then use this preform to carry out the above-mentioned main molding. In the manufacturing method of the present invention, after placing a part of the whetstone base in an exposed state in a mold for forming a whetstone, the air space between the exposed part of the base and the inner wall of the mold is
is filled with the above-mentioned compound, and the abrasive grain layer is formed in the same manner as described above to produce a wheel in which the abrasive grain layer 1 is directly bonded to the grindstone base 2 as shown in FIGS. 1 and 2. It is also possible to manufacture a grindstone 3 having a shape. Examples of the material for the grinding wheel base include metal bases such as aluminum and steel, and cured materials such as epoxy resins and phenolic resins reinforced with appropriate fillers. EXAMPLES Hereinafter, examples related to the present invention will be shown and the present invention will be explained more specifically. Example 1 High molecular weight polymer obtained by polymerizing approximately equimolar amounts of 3,3',4,4'-biphenyltetracarboxylic acid or its acid dianhydride and 4,4'-diaminodiphenyl ether. Aromatic polyimide powder (average particle size;
15μm, second order transition temperature; 285℃, 5% weight loss temperature; 575℃, logarithmic viscosity; 3.2, specific gravity after molding:
1.48) 11.36 parts by weight and 200 mesh of nickel-clad synthetic diamond (specific gravity: 5.1)
A mixture prepared by dry mixing 24.73 parts by weight (the weight of artificial diamond (specific gravity: 3.49) is 15.95 parts by weight) was placed in a predetermined mold containing an aluminum grinding wheel base. It was first preformed by filling it into a container and pressurizing it for 5 minutes at a temperature of 250℃ and a pressure of 1000Kg/ ^cm2 , then heating it to 310℃ and pressurizing it for 5 minutes at a pressure of 2000Kg/ ^cm2 . Pressure forming (main forming) was performed to form a grinding wheel having the shape shown in FIG. 1 and having an abrasive grain layer directly integrated with the periphery of the grinding wheel base. The abrasive grain layer contained 25% by volume of artificial diamond. The grinding wheel was subjected to a grinding performance test (grinding test) under the conditions shown below, and the results are shown in Table 1. Grinding wheel shape (dimensions mm) 1A1 (JIS standard) 200 ^D × 6 ^T × 3 ^X × 50.8 ^H Material to be ground Cermet (Mitsubishi Metals, Ltd.)
NX55), or cemented carbide (manufactured by Mitsubishi Metals Corporation,
GTi30) Grinding machine Manufactured by Okamoto Machine Tool Co., Ltd., surface grinding machine
PSG-63A 3.7KW Grinding conditions are shown in Table 1. Grinding fluid: Chemical 1:50 aqueous solution. Comparative Experimental Examples 1-2 A pyromellitic acid-based aromatic polyimide powder is used as a binder, and the shape is the same as that of Experimental Example 1 with an abrasive layer containing artificial diamond in the same proportion as Experimental Example 1. A grinding test similar to Experimental Example 1 was conducted using a grindstone manufactured by Company A (Comparative Experimental Example 1) and a grindstone manufactured by Company B (Comparative Experimental Example 2). The results are shown in Table 1. Comparative Experimental Example 3 A grinding wheel having the same shape as in Experimental Example 1 was prepared except that phenolic resin was used as a binder, and a grinding test was conducted on the grinding wheel. The results are shown in Table 1.

[Table] The grinding wheel of Experimental Example 1 shows a higher grinding ratio in carbide grinding than the comparative experimental examples, and is also capable of stably grinding TiN-based cermet, which is said to be extremely difficult to grind, from beginning to end. It was hot.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of the grindstone of the present invention, and FIG. 2 is a sectional view of the grindstone. 1; Abrasive grain layer, 2; Grinding wheel base, 3; Grinding wheel.

Claims (1)

[Scope of Claims] 1 100 parts by weight of abrasive grains, an aromatic tetracarboxylic acid component containing 50 mol% or more of biphenyltetracarboxylic acid or its acid dianhydride, and an aromatic diamine component are polymerized and imided. 20 to 150 parts by weight of an aromatic polyimide powder, the polymer of which has a secondary transition temperature of 250 to 380°C, is pressure-molded from a blend containing at least 20 to 150 parts by weight of an aromatic polyimide obtained by A heat-resistant resin-bonded grindstone characterized by having an abrasive grain layer containing abrasive grains at a ratio of 5 to 50% by volume. 2. The heat-resistant resin bonded grindstone according to claim 1, wherein the abrasive grain layer is directly and integrally bonded to the surface of the grindstone base. 3. An aroma obtained by polymerizing and imidizing 100 parts by weight of abrasive grains, an aromatic tetracarboxylic acid component containing 50 mol% or more of biphenyltetracarboxylic acid or its acid dianhydride, and an aromatic diamine component. A mold is filled with a blend containing at least 20 to 150 parts by weight of aromatic polyimide powder, which is made of polyimide of the group polyimide group and has a secondary transition temperature of 250 to 380°C. At temperatures higher than the second-order transition temperature of group polyimides, 100~
A method for manufacturing a heat-resistant resin-bonded grindstone, which is characterized by forming an abrasive grain layer by applying pressure to 5000 Kg/cm ² . 4. After arranging a part of the grinding wheel base in a mold in an exposed state, the cavity between the exposed part of the base and the inner wall of the mold is filled with the compound to form an abrasive grain layer. A method for manufacturing a heat-resistant resin-bonded grindstone according to claim 3, wherein the grindstone base and the abrasive grain layer are directly joined together.