JP2008105169A - Paste material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paste material having a good surface treatment efficiency relating to the paste material for performing a noncontact surface treatment with the interlocking of the action of a magnetic field. <P>SOLUTION: The paste material 4 includes four components of magnetic particles 41, treatment particles 42, resin particles 43, and a solvent 44. The solvent 44 is water, the resin particles 43 are made of resin materials not dissolved in the solvent, and the composition is prepared such that polyhydric alcohol such as glycerin is added as an additive for suppressing the drying and improving the stability of a dispersion state. The treatment particles are composed of magnetic materials such as Mn-Zn ferrite. When the magnetic field of a permanent magnet 20 is actuated, the magnetic particles 41 are mutually attracted to generate a magnetic cluster. The treatment particles are made of the magnetic materials, thereby the treatment particles are surely trapped by the magnetic cluster, thereby suppressing them from oozing out from a magnetic brush. As a result, the surface treatment efficiency is improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a paste material for performing non-contact surface treatment by interlocking with the action of a magnetic field, and is suitable for surface treatment such as polishing and cleaning on the surface of a metal material, a resin material, etc. Paste material.

  As polishing techniques for precisely polishing the surface to be polished, processing methods such as lapping, CMP (Chemical Mechanical Polishing), and float polishing are well known.

  Also, as a final polishing using magnetism, a polishing technique using a magnetic fluid (MF) or a magnetorheological fluid (MRF) is known, and MF or MRF is mixed with abrasive particles. Polishing is performed by moving the liquid mixture by a magnetic field.

  This magnetic polishing liquid (paste material) is formed by mixing abrasive particles with MF or MRF. When the magnetic polishing liquid is attached around a polishing tool provided with a permanent magnet as a magnetic field generation source, a large number of ferromagnetic particles (for example, iron particles) and magnetite particles in MF and MRF are generated by magnetic attraction. Aggregates to form magnetic clusters. Since this magnetic cluster follows the magnetic flux, it takes a form in which a large number of needles are arranged in opposition to the object to be polished. Therefore, the magnetic polishing liquid adheres to the polishing bite to form a magnetic brush.

  Then, when the magnetic brush or the object to be polished rotates, the magnetic brush moves in a state of contacting the surface of the object to be polished by relative movement between them. As a result, the unevenness of the surface to be polished is polished by a magnetic brush with abrasive particles, a smoother surface is obtained, and non-contact fluid polishing (surface treatment) is performed.

  As a technique related to a magnetic polishing liquid for performing non-contact fluid polishing by the action of such a magnetic field, for example, there is an invention disclosed in Patent Document 1. This Patent Document 1 discloses a magnetic polishing liquid in which non-magnetic abrasive particles are mixed with a composite fluid in which ferromagnetic particles, kerosene, etc. are mixed in a solvent, and α-cellulose or the like is further mixed as a thickener. ing.

International Publication WO2006 / 030854

  However, such conventional magnetic polishing techniques have the following problems. Magnetic polishing by MF requires a long time magnetic polishing because magnetic particles are weakly fixed when a magnetic field is applied and polishing efficiency is low. Further, since MF is obtained by uniformly dispersing magnetic particles having a particle diameter of about 10 nm, it is difficult to clean after polishing, and magnetic particles are clogged in minute gaps and cannot be removed.

  In the polishing by MRF, ferromagnetic magnetic particles are strongly fixed in a needle shape by a magnetic field to form a so-called magnetic cluster, and polishing is performed by pressing the abrasive particles against the polishing surface by this magnetic cluster. Difficult, deep scratch marks are easily formed on the surface to be polished, and there is room for improvement in application to fine finishing.

  Further, non-magnetic particles such as alumina are generally used as the abrasive particles constituting the magnetic polishing liquid. Some of the nonmagnetic particles are not trapped in the magnetic cluster due to the influence of the external magnetic field generated by the magnet of the polishing tool, and ooze out from the magnetic brush. Therefore, there are problems such as contamination of the processed surface and reduction in polishing efficiency.

  Further, the thickener such as α-cellulose disclosed in Patent Document 1 acts to retain magnetic clusters, and as a result, promotes a state in which a large number of abrasive particles can come into contact with the surface of the object to be polished. It is used to perform polishing with high efficiency.

  By the way, when water is used as a solvent, it is not flammable and it is not necessary to provide an explosion-proof structure or local exhaust equipment, which is preferable from the viewpoint of environmental safety as well as reducing the equipment cost. However, the thickener such as α-cellulose used in Patent Document 1 has a problem that it cannot be used because it dissolves in water.

  In addition, the present inventors previously described, in Japanese Patent Application No. 2006-159529, “magnetic particles, abrasive particles of nonmagnetic particles such as alumina, water as a solvent, and resin particles that are not soluble in water. A magnetic polishing solution containing four components was proposed. And polymethylmethacrylate was illustrated as a specific example of the resin particle.

  In the invention according to this prior application, when a magnetic field is applied, the magnetic particles adsorb each other. At this time, there are resin particles insoluble in water between the magnetic particles. Therefore, since the resin particles are elastically deformed when interlocking with the movement of the polishing tool, the processing pressure in fluid polishing is reduced, and scratches are less likely to occur. That is, the resin particle expresses the function of the elastic member.

  Further, since the resin particles are dispersed and sandwiched between the respective compositions, the aggregate of magnetic particles (magnetic cluster) has an overall bulge. The resin particles express the function of a spacer member that increases the bulk of the entire magnetic cluster. Therefore, the magnetic cluster has a large protrusion from the magnetic field generation source, and the interval between the polishing tools can be set wide with respect to the object to be polished, thereby increasing the convenience of magnetic polishing.

  In this case, since the resin particles are formed from a resin material that does not dissolve in the solvent, there is no interference with water as the solvent, and a good polishing ability can be obtained.

  Therefore, in the above-mentioned invention of the prior application, highly precise surface polishing can be performed by the above-mentioned effects, and since the resin or the like is mixed, the brush has elasticity and is soft.

  As described above, the invention of the prior application was able to provide an excellent magnetic polishing liquid from a certain point. And, in the case of a magnetic polishing liquid in which resin particles such as PMMA are mixed, the effect as final polishing is very high in polishing efficiency. For example, polishing on a relatively rough polishing object having a surface roughness Ry = 5 μm or more It takes time. This seems to be because the brush itself is elastic and soft by mixing resin or the like.

  Furthermore, a part of the non-magnetic particles is not trapped in the magnetic cluster due to the influence of the external magnetic field generated by the magnet of the polishing tool and the centrifugal force generated by the rotational movement of the polishing tool. As a result, the non-magnetic particles contaminate the processed surface to be polished by oozing out from the magnetic brush, and the polishing efficiency is reduced due to the decrease in the amount of abrasive particles that are non-magnetic particles due to oozing out. Furthermore, since the volume ratio of the magnetic particles is reduced by adding the resin component, there is a problem that the holding power by the magnetic field is reduced and the polishing efficiency is reduced.

  FIG. 1 is a diagram schematically showing a conventional magnetic polishing system in which nonmagnetic particles such as alumina are used as polishing particles 42. A magnetic polishing liquid having magnetic particles 41, nonmagnetic particles 42, and a solvent 44 is attached to the polishing bit 2 having the permanent magnet 20 by forming a magnetic cluster by magnetic attraction. As shown in the figure, the magnetic particles 41 are attracted to the permanent magnet 20 more strongly than the non-magnetic particles 42 and are affected by the centrifugal force due to the rotational operation of the polishing tool. In addition, a part of the abrasive particles 42 which are nonmagnetic particles are pushed out and become nonmagnetic particles by exuding from the magnetic brush.

  The present invention solves the above-mentioned problems, and an object thereof is to provide a paste material having a high processing efficiency such as polishing, and still another object is a resin material that could not be polished by an automatic polishing method until now. It is also possible to polish.

  In order to achieve the above-described object, the paste material according to the present invention is present in the vicinity of a magnetic field generation source facing the object to be processed in a non-contact manner for surface treatment, and is interlocked by the action of the magnetic field. However, at least magnetic particles for forming magnetic clusters, treated particles having magnetism, and a solvent are included.

  Examples of the surface treatment include polishing treatment and cleaning treatment. In the case of the polishing process, the paste material is a magnetic polishing liquid (paste material) that is present around the polishing bite that faces non-contact with the object to be polished in order to perform fluid polishing, and is interlocked by the action of a magnetic field, It can also be configured to include at least magnetic particles for forming magnetic clusters, abrasive particles having magnetism, and a solvent.

  The treated particles can be ferrite particles. In addition, the treated particles are ferrite particles obtained by sintering a pressure-molded body of raw material granulated powder and mechanically pulverized, or ferrite particles fired without forming the raw material granulated portion. May be.

  “Crushing with mechanical force” means crushing by pressurization, for example, using a pulverizer, a crusher, a ball mill or the like. For example, MnZn-based ferrite can be used, but other ferrites may be used.

  The treated particles may have a saturation magnetization (Bs) of 100 mT or more. The magnetic particles may be formed of a magnetic material having a saturation magnetization of 7 kG or more in volume magnetization. Furthermore, the solvent may be water, and the magnetic particles may be cobalt (powder).

  When the solvent is water, cobalt (powder), Sendust (registered trademark), or the like can be used as the magnetic particles. When the solvent is an organic solvent, the magnetic particles may be iron (powder), cobalt, Sendust (registered trademark), or the like.

  When the solvent is water, a polyhydric alcohol such as glycerin may be added as an additive for improving drying suppression and dispersion stability. Moreover, it is good to mix the rust preventive which suppresses the rust to a process target (polishing object), a processing apparatus (polishing apparatus), etc. with paste material. Furthermore, the magnetic particles are preferably formed from a magnetic material having oxidation resistance to water.

  Meanwhile, the solvent may be an organic solvent, and the magnetic particles may be iron. Further, the solvent may be oil and fat, and the magnetic particles may be iron. In particular, when the object to be polished is aluminum, it is possible to reduce pollution by using oils and fats.

  The magnetic particles may be non-spherical particles. When the magnetic particles (magnetic powder) are non-spherical particles, agglomerates having spaces are formed and water is easily absorbed. As a result, the magnetic particles are hardly precipitated and a polishing liquid with high dispersion stability is obtained.

  Furthermore, a low melting point resin that is insoluble in the solvent may be mixed uniformly in the solvent. At this time, the solvent may be vegetable oil. The low melting point resin is, for example, about 100 ° C. or less. This is because the resin having a melting point of about 100 ° C. has a molecular weight of about 1000, but the resin having a melting point of about 120 ° C. has a molecular weight of about 10,000 and becomes hard. And it becomes a branching point where the molecular weight rapidly increases near the temperature exceeding 100 ° C. Therefore, it can be said that the resin of 100 ° C. or less before the increase is a low melting point resin.

  More preferably, the melting point of the low melting point resin is 40 ° C. or higher and 80 ° C. or lower. When the melting point of the resin particles is too low, the lower limit is preferably 40 ° C. or more because the resin particles are liquefied due to changes in the environmental temperature and cause precipitation of the ferrite particles. However, if the temperature is too high, it becomes hard and the compatibility with the solvent decreases, so the upper limit is preferably 80 ° C. or lower.

  The treated particles may have a corner shape. Thus, in order to give a corner | angular part to a particle shape, it is good to use the particle | grains which grind | pulverized the sintered compact with the mechanical force. By having the corners, the polishing power and the like are improved.

  In the present invention, the treated particles (abrasive particles) are treated particles having magnetism. Therefore, the processed particles themselves are not attracted to and pushed out by the magnetic field source (such as the permanent magnet of the bite), and the processed particles are separated from the magnetic cluster by the centrifugal force generated by the rotation of the magnetic field source (polishing bite). It does not push outward. As a result, the treated particles are reliably trapped in the magnetic cluster and suppressed from oozing out of the magnetic brush. Therefore, polishing efficiency is improved.

  When the saturation magnetization (Bs) of the treated particles is less than 100 mT, it takes time to polish, or if the surface roughness before polishing is rough, polishing becomes impossible. Therefore, the saturation magnetization (Bs) of the treated particles is preferably 100 mT or more. Of course, since polishing is possible even if it is less than 100 mT, 100 mT or more is not an essential requirement.

  When the magnetic particles are made of a magnetic material that has oxidation resistance to water, and the magnetic material is a magnetic material having a saturation magnetization of 7 kG or more in volume magnetization, the processing characteristics (polishing characteristics) of the paste material (magnetic polishing liquid) It is possible to prevent the deterioration of the film and to obtain a high polishing ability.

  When water is used as a solvent, it is not flammable and it is not necessary to provide an explosion-proof structure or local exhaust equipment, which is preferable from the viewpoint of environmental safety as well as reducing equipment costs. Further, when resin particles are added, the magnetic particles are mutually adsorbed when a magnetic field is applied, and at this time, resin particles that are insoluble in water exist between the magnetic particles. When interlocking with the movement of a magnetic field generating source such as a polishing tool, the resin particles become elastic and deformed, so the processing pressure in fluid polishing is reduced and the resin particles exhibit the function of an elastic member. To do. As a result, scratches are less likely to occur.

  The resin particles are dispersed and sandwiched between the respective compositions, and the aggregate (magnetic cluster) of the magnetic particles is swollen as a whole. That is, the resin particles exhibit the function of a spacer member that increases the bulk of the entire magnetic cluster. Therefore, the magnetic cluster has a large protrusion from the magnetic field generation source side, and the interval between the polishing tools can be set wide with respect to the object to be polished, thereby increasing the convenience of magnetic polishing. In this case, since the resin particles are formed from a resin material that does not dissolve in the solvent, there is no interference with water as the solvent, the polishing ability can be obtained well, and highly accurate surface polishing can be performed. It should be noted that α cellulose which has been generally used in the past cannot be used because it dissolves in water.

  When a polyhydric alcohol such as glycerin is added as an additive, evaporation can be suppressed and the stability of the dispersed state can be improved. Moreover, since a rust inhibitor is added, rusting of the polishing object and the polishing apparatus can be prevented.

  In addition, unlike the resin particles, when a low melting point resin that is insoluble in the solvent is mixed in the solvent, the resin particles and the solvent are fluid due to stress while maintaining the shape by compatibility. It can be. When there is no stress at which no external force acts, the low melting point resin holds the ferrite particles in the solvent, so that sedimentation can be suppressed. Moreover, even if it precipitates, mixing can be performed easily. And when an external force is applied, it can flow due to the fluidity of the solvent. Therefore, when this paste material is used for polishing treatment or the like, it is possible to prevent a reduction in polishing power due to an increase in viscosity.

  When only a small amount of low melting point resin is mixed, it causes separation of ferrite particles and solvent. However, since resin particles exist between ferrite particles, dispersibility is improved and mixing is facilitated. It is valid. The mixing amount of the low melting point resin is determined according to the melting point, the particle diameter, the shape maintenance degree of the magnetic polishing liquid, and the viscosity of the resin particles.

  The melting point of the low melting point resin is, for example, about 100 ° C. or less. This is because the resin having a melting point of about 100 ° C. has a molecular weight of about 1000, but the resin having a melting point of about 120 ° C. has a molecular weight of about 10,000 and becomes hard. And it becomes a branching point where the molecular weight rapidly increases near the temperature exceeding 100 ° C. Therefore, it can be said that the resin at 100 ° C. or less before the increase is a low melting point resin.

  Furthermore, if the melting point of the low melting point resin is too low, the melting point is preferably 40 ° C. or higher because the low melting point resin liquefies due to changes in the environmental temperature and causes precipitation of ferrite particles. However, if the temperature is too high, it becomes hard and the compatibility with the solvent decreases, so the upper limit is preferably 80 ° C. or lower. Examples of resin materials that do not dissolve in vegetable oils include polyethylene and polystyrene. The resin particles and the low melting point resin are different from each other in action and effect.

  In the paste material according to the present invention, the processing particles do not ooze out and the polishing efficiency is improved. Furthermore, it can grind | polish without contaminating the surface of grinding | polishing object. Conventionally, it has been essential to add a resin or the like in order to hold non-magnetic abrasive particles in a magnetic cluster. However, in the present invention, by using treated particles having magnetism, the treated particles themselves become magnetic clusters. The effect which forms is exhibited. In addition, by making the treated particles themselves magnetic, the adhesion of the magnetic brush to the magnetic field generating source such as a magnetic bite is increased, and the movement of the magnetic brush is improved in accordance with the movement of the magnetic field generating source (processing bite). This also increases the polishing efficiency.

  Further, when ferrite particles are used as the treatment particles having magnetism, there is an effect in that a rough processed surface is polished.

  FIG. 2 shows a preferred embodiment of the present invention. In this embodiment, the paste material is used for so-called magnetic polishing. In this embodiment, the configuration for performing magnetic polishing includes a polishing bit 2 having a magnetic field generation source (20), the polishing target 1 is fixed to the y-axis stage 3, and the polishing bit 2 is not in contact with the polishing target 1 The magnetic polishing liquid 4 is present between the polishing object 1 and the magnetic polishing liquid 4 is mixed with abrasive particles, and the polishing tool 2 is connected to a driving means 5 associated therewith. By starting, a predetermined motion operation is performed, and by starting the y-axis stage 3, the polishing object 1 is caused to perform a predetermined motion operation on the y-axis, and fluid polishing is performed by the magnetic cluster generated in the magnetic polishing liquid 4. Is supposed to do.

  The polishing tool 2 is provided with a permanent magnet 20 at its tip to serve as a magnetic field generation source. The magnetic field generation source is not limited to the permanent magnet 20, and for example, an electromagnet can be preferably applied as long as it can act on the magnetic polishing liquid 4. The generation of the magnetic field does not have to be stationary in time, and a magnetic field that varies in time may be generated.

  The driving means 5 has a multi-axis control function for at least the x-axis and z-axis. When the driving means 5 is activated, the polishing tool 2 rotates and moves in a predetermined manner with respect to the x-axis and z-axis. Let the action take place. Of course, you may make it reciprocate in a uniaxial direction. As the driving means 5, for example, an NC machine tool may be used, and the shaft portion of the polishing tool 2 is attached to and detached from a rotating shaft (chuck portion) such as a drilling machine, a lathe, an NC lathe, or a milling machine.

  FIG. 3 is an explanatory view schematically showing a magnetic polishing liquid according to the present invention, showing a state in which a magnetic field acts, and showing a so-called magnetic cluster.

  The magnetic polishing liquid 4 includes at least three components of magnetic particles 41, magnetic polishing particles 45, and a solvent 44. The solvent 44 was water. And you may add polyhydric alcohols, such as glycerol, as an additive which improves drying control and stability of a dispersion state. The magnetic polishing liquid 4 may be mixed with a rust preventive agent that suppresses rust on the polishing object 1 and the polishing apparatus. For example, an anionic surfactant is used as the rust inhibitor, and an appropriate amount that does not adversely affect the polishing ability is added. This magnetic polishing liquid 4 is supplied by a supply means between the polishing object 1 and the polishing bit 2.

  In the present embodiment, the abrasive particles 45 are made of a magnetic material, and are made of, for example, MnZn-based or other ferrite powder. Thus, since the abrasive particles 45 have magnetism, both the abrasive particles 45 and the magnetic particles 41 are attracted to the permanent magnet. As a result, as shown in FIG. 3, magnetic clusters are formed in such a manner that the abrasive particles 45 are taken into the magnetic particles 41.

  In this embodiment, by providing the abrasive particles 45 having magnetism, it is not necessary to use a thickener such as a resin. When no thickener is used as in this embodiment, the volume ratio of the magnetic particles 41 Therefore, the holding power by the magnetic field does not decrease, so that the polishing efficiency is increased.

  The abrasive particles of the present embodiment are hard because they are made of a magnetic material. Therefore, rough polishing is possible (suitable).

  When MnZn-based ferrite is used, the saturation magnetization is generally 400 mT. The average particle diameter of the abrasive particles 45 is 0.01 μm to 100 μm. The particle diameter and type of the abrasive particles 45 may be changed and set as appropriate depending on the material and surface roughness of the object 1 to be polished.

  In this embodiment, since the solvent 44 is water, the magnetic particles 41 are preferably formed from a magnetic material having oxidation resistance to water, and are formed from a magnetic material having a saturation magnetization of 7 kG or more in volume magnetization (4πM). is doing. Specifically, the magnetic particles are preferably formed from cobalt.

  The magnetic particles 41 have an average particle diameter of 0.01 μm to 500 μm, and more preferably 0.5 μm to 50 μm. This is because when the average particle size is excessively small, the response due to the magnetic field becomes extremely weak and polishing becomes impossible. Conversely, when the particle size is excessively large, the stability of the dispersion state is deteriorated and it becomes difficult to control the polishing. .

  As the magnetic particles 41, a magnetic material that is disadvantageous in terms of oxidation resistance to water, such as iron or an iron-based alloy, can be used. In other words, such a magnetic material may be used without any inconvenience, for example, by covering the surface so as not to react with water and by taking appropriate measures for water resistance and oxidation resistance.

  Although the solvent of this embodiment used water, you may use an organic solvent. In this case, however, an explosion-proof structure or local exhaust is performed to suppress ignition.

  Moreover, iron can also be used as a magnetic particle.

  Further, resin particles may be further mixed. In this case, the resin particles are preferably formed from a resin material that does not dissolve in the solvent 44, and the average particle diameter is preferably several μm to several hundred μm. The shape of the resin particles may be, for example, a spherical shape, or may be formed in a non-spherical shape such as a fibrous shape. Examples of resin materials that do not dissolve in water include polyethylene (PE), polystyrene (PS), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and polyvinyl chloride (PVC). The shape of the resin particles may be non-spherical particles such as fibers in addition to the spherical shape.

  The movement operation of the polishing tool 2 is, for example, an operation of scanning the entire surface of the polishing object 1 or a predetermined movement of the polishing object 1 with respect to the xy plane by setting the operation of the y-axis stage 3 and the driving means 5. An operation may be performed. At this time, the magnetic polishing liquid 4 is supplied to the periphery of the polishing tool 2, and the polishing tool 2 is caused to perform a rotating operation that reverses forward and backward in the axial direction. Or it is good also to perform the vibration operation | movement which vibrates predetermined.

  A magnetic polishing liquid 4 exists between the polishing tool 2 and the polishing object 1, and the magnetic polishing liquid 4 includes abrasive particles 42, and the permanent magnet 20 changes the magnetic polishing liquid 4 to be constant or variable in time. When a magnetic field is applied, a magnetic cluster is generated. That is, a large number of magnetic particles 41 in the magnetic polishing liquid are aggregated by the magnetic attractive force to form a magnetic class. Since the magnetic class is along the magnetic flux, a large number of needles are arranged in opposition to the object 1 to be polished, whereby the abrasive particles 42 present in the magnetic polishing liquid are held down on the surface of the object 1 to be polished. At this time, since the polishing tool 2 and the polishing object 1 move relative to each other, the abrasive particles 42 move while contacting the surface of the polishing object 1 to perform cutting (grinding).

  When a magnetic field is applied to the magnetic polishing liquid 4, the magnetic particles 41 are attracted to each other as shown in FIG. Further, since the abrasive particles 45 are made of a magnetic material such as ferrite powder, the abrasive particles can be prevented from staying in the magnetic brush by the magnet of the abrasive bite and flowing out to the outside. Easy to do.

  Since the solvent 44 is water and no organic solvent is used, an explosion-proof structure and local exhaust are not required, which is advantageous in terms of environmental safety. Since a polyhydric alcohol such as glycerin is added as an additive, evaporation can be suppressed and the stability of the dispersed state can be improved. Moreover, since a rust inhibitor is added, rusting of the polishing object 1 and the polishing apparatus can be prevented.

  Further, the magnetic particles 41 are formed of a magnetic material having oxidation resistance to water, and the magnetic material is a magnetic material having a saturation magnetization of 7 kG or more in volume magnetization (4πM), so that the polishing characteristics of the magnetic polishing liquid are deteriorated. Can be prevented, and a high polishing ability can be obtained.

  The sample was polished according to the configuration for magnetic polishing shown in FIG. That is, in order to demonstrate the effect of the present invention on the polishing ability, a plurality of magnetic polishing liquids having different compositions are prepared, the sample is polished with each magnetic polishing liquid, and the surface roughness Ra (arithmetic average roughness) after polishing is prepared. And Ry (maximum roughness).

The composition of the magnetic polishing liquid is as follows: cobalt (magnetic particles 41), ferrite powder (polishing particles 42), and water (solvent) in wt% shown in Table 1, and a ratio of 3% glycerol mixed with water. Two examples were prepared by adding in and mixing them uniformly. In Example 1, resin particles were not used. Further, as Example 2, resin particles were mixed. Further, as a comparative example, alumina was used as abrasive particles, and resin particles with a particle size of 20 μm added were prepared.

  The object to be polished was a plate piece (Ry = 5.7 μm) made of acrylic resin, and the surface was polished. This object to be polished was reciprocated at 30 mm at 2 mm / sec in the x-axis direction. A neodymium magnet was used as the permanent magnet 20 of the magnetic field generation source, and the polishing time was 10 minutes. The surface roughness was measured by a surface roughness level meter, and P-10 manufactured by Tencor Corporation was used for this. When the object to be polished was polished, the results shown in FIG. 4 were obtained.

  FIG. 4 shows the surface roughness before and after polishing of the polishing target of Example 1 that does not contain resin particles. The surface roughness was measured by a surface roughness step meter (manufactured by Tencor: P-10). As is apparent from the figure, in Example 1, the surface roughness of Ry = 5.7 μm before polishing was a transparent surface with Ry = 0.14 μm. In the comparative example, polishing was not possible at all.

Next, in order to demonstrate the effect of the present invention regarding the relationship between the polishing time and the polishing roughness, the polishing roughness was measured for the above Examples 1 and 2 while changing the polishing time. As a result, the results shown in Table 2 and FIG. 5 were obtained. It becomes transparent visually when Ry is 0.2 μm or less. Therefore, it was confirmed that the polished surface became transparent in 1 minute or more. When the polishing time was 10 minutes, the comparative example could not be polished.

FIG. 6 is a diagram showing the polishing roughness with respect to the polishing time. Moreover, the photograph figure shown on the right side has shown the state which the grinding | polishing object grind | polished the surface with respect to an acrylic resin, the acrylic resin after a process (back side is transparent) is set | placed on a document, and was visually observed from the top. When polishing time becomes visible from 1 minute and Ry = 0.2 μm, which is visually transparent, in the case of Example 1, desired properties can be achieved in 5 minutes, and polishing efficiency is excellent. It could be confirmed.

  Next, a comparison was made between a wet polishing method which is a premise of the present invention and a dry polishing method (comparative example). MnZn-based ferrite was used as the ferrite powder. As the ferrite powder, a powder obtained by sintering a pressure-molded body of raw material granulated slag was pulverized with a pulverizer. No special process is required after grinding. Cobalt was used for the magnetic particles. The solvent was water. On the other hand, in the dry type, the magnetic particles are cobalt, the abrasive particles are ferrite, and there is no solvent.

As a result, as shown in FIGS. 7 to 9 and Table 3, it can be confirmed that the wet polishing has a smaller surface roughness and a higher transmittance. Specifically, in the case of a wet process, the transmittance becomes 88% or more after a polishing time of 5 minutes. On the other hand, in the dry process, when the polishing time is 5 minutes, the transmittance is only about 72%, and even when the polishing time is 10 minutes, the transmittance is about 79%. Further, in the case of the dry method, since there is no solvent, the abrasive grains are difficult to disperse and the polishing unevenness increases.

  Next, a polishing process was performed using a polishing wax as a modeling wax (modeling wax). Modeling wax is a material used in making a prototype for the purpose of confirming the shape in the design and design field. This modeling wax is characterized by being soft and having good processability. As the magnetic polishing liquid, the magnetic particles were cobalt powder (50 wt%), the abrasive particles were ferrite (24 wt%), the solvent was water (23 wt%), and the additive was glycerin (humectant) (3 wt%).

  As a result, Ra: 0.81 μm and Ry: 8.49 μm before polishing, but Ra: 0.20 μm, Ry: 1.99 μm after polishing, and the surface roughness is improved to 1/4 or less. The surface gloss can be obtained.

  Moreover, the same experiment was conducted when the object to be polished was aluminum. As the magnetic polishing liquid, one having magnetic particles of iron (37.5 wt%), polishing particles of ferrite (37.5 wt%), and solvent of oils and fats (25 wt%) was used. As a result, Ra: 0.884 μm and Ry: 6.033 μm before polishing, whereas Ra: 0.280 μm and Ry: 2.723 μm after polishing.

  Next, the characteristics of the magnetic polishing liquid according to the shape of the magnetic particles constituting the magnetic polishing liquid were verified. Specifically, spherical and non-spherical magnetic particles were produced and evaluated. The magnetic polishing liquid was composed of sendust (26 wt%) as magnetic particles, ferrite (26 wt%) as abrasive particles, and water (48 wt%) as a solvent. The sample roughness before polishing was Ra: 1.056 μm, Ry: 6.677 μm.

  As the shape of the magnetic particle, a spherical one was produced by an atomizing method, and a non-spherical one was produced by micronizing by mechanical pulverization (shearing). Since the magnetic particles are metal, they are flattened by mechanical pulverization.

  As a result, as shown in Table 4 below, it was confirmed that the water absorption amount was increased by the non-spherical particle method compared to the spherical particle. In addition, in the case of a magnetic polishing liquid using non-spherical particles, the dispersibility does not cause precipitation even after 7 days from preparation, and the dispersibility remains in a good state, but in the case of spherical particles, precipitation occurs. It was confirmed that the dispersibility was poor.

  Further, when each magnetic polishing liquid was used for polishing for 1 minute, as shown in Table 4, the roughness after polishing was almost the same for all particles. This makes it possible to increase dispersion stability without reducing the polishing ability by making the ferromagnetic powder non-spherical, and it is not necessary to re-stir during use, or it is easily uniform and easy to handle. It becomes a magnetic polishing liquid.

In the above experiment, the non-spherical shape is flat, but any shape may be used as long as it absorbs water, such as a fiber shape or an indefinite shape.

An experiment was conducted to verify the effect of obtaining dispersion stability by mixing a low melting point resin in a solvent. That is, the magnetic polishing liquid was composed of iron powder (magnetic particles 41), ferrite powder (polishing particles 42), and vegetable oil (solvent) in wt% as shown in Table 5. In Table 5 below, the hydrocarbon-based resin refers to a resin composed of only carbon and hydrogen, and refers to resins such as polyethylene and polystyrene. The alcohol-terminated resin refers to a resin having an —OH group in the molecular chain, and examples thereof include polyvinyl alcohol and polymethyl methacrylate.

  Various amounts of various resins were mixed in this solvent. The state of dispersion stability of various magnetic polishing liquids and whether or not polishing was possible using the magnetic polishing liquid after being left for one week after the polishing liquid was prepared were determined. The results are shown in Table 6.

The magnetic polishing liquid was prepared by mixing a predetermined amount using a mixer, and remixed when polishing the polishing paper one week later. Moreover, the grinding | polishing object was made into the board piece which consists of acrylic resins, and the surface was grind | polished. This polishing object was made to reciprocate by 20 mm in the x-axis direction. The permanent magnet 20 of the magnetic field generation source was rotated at 500 rpm, the distance from the sample was 0.5 mm, and the polishing time was 2 minutes.

  From the above results, the particle surface treatment (Comparative Examples 1 and 2) did not show the effect of dispersion stability, and was not significantly different from the untreated. When a high melting point resin that is insoluble in a solvent is mixed (Comparative Examples 4 and 5), it is possible to suppress precipitation, but after standing for one week, the polishing liquid becomes hard and mixing is difficult and lacks stability. I understood it. The mixing of the resin soluble in the solvent (Comparative Example 6) increases the viscosity when the resin is dissolved in the solvent and suppresses the precipitation, but cannot be polished due to the increased viscosity. The mixing of the surfactants (Comparative Examples 7 and 8) is not effective because there is no dispersion effect in a small amount, and a slight effect can be seen by mixing in a large amount but polishing becomes impossible.

  Therefore, an effective method is mixing of low melting point resins insoluble in a solvent (Examples 1 to 4), and a small amount of mixing causes separation, but mixing is easy and can be confirmed to be effective. It was.

  Next, the magnetic polishing liquid 4 is composed of a magnetic powder (iron powder), a ferrite powder (MnZn ferrite), and a solvent (vegetable oil) in wt% shown in Table 7, and variously mixed by uniformly mixing them. Samples were prepared.

MnZn ferrite having a saturation magnetic flux density at room temperature of about 510 mT was used. The ferrite particles include those having an average particle diameter of 15 μm and those having a particle diameter of 4 μm to 50 μm, those having an average particle diameter of 100 μm include those having a particle diameter of 40 μm to 200 μm, and those having an average particle diameter of 220 μm include those having a particle diameter of 100 μm to 400 μm. The average particle size of 400 μm includes particles having a particle size of 250 μm to 700 μm.

The object to be polished was a plate piece (Ry = 5.7 μm) made of acrylic resin, and the surface was polished. This polishing object 1 was reciprocated by 30 mm at 2 mm / sec in the x-axis direction. A neodymium magnet was used as the permanent magnet 20 of the magnetic field generation source, and the polishing time was 2 minutes. The surface roughness was measured by a surface roughness level meter, and P-10 manufactured by Tencor Corporation was used for this. When the object to be polished was polished, the results shown in Table 8 were obtained.

  As is apparent from Table 8, when the ferrite particles have an average particle diameter of 15 μm, the sample 1 to which no iron powder is added and the samples 2 and 3 to which only a small amount is added cannot be or are not easily polished. Polishing is possible by mixing. When the average particle diameter of the ferrite particles is 100 μm, polishing is possible without adding iron powder, and the polishing power is slightly deteriorated by mixing the iron powder. Further, when the average particle diameter of the ferrite particles is set to 220 μm or 400 μm, scratches begin to enter.

  In other words, when the average particle diameter is small, the ferrite particles need to have a magnetic brush strengthened by increasing the magnetization (magnetic moment) with the iron powder. However, when the average particle size is increased and the saturation magnetic flux density per particle is increased, polishing can be performed using only ferrite particles. However, it was confirmed that the scratches increased as the average particle size increased.

  FIG. 2 is a graph showing the measurement results of the surface roughness of the object to be polished, and the surface roughness before polishing and the surface roughness after polishing in Example 1 and Sample 1 are displayed. As can be seen from the figure, in Example 1, the surface roughness after polishing was substantially zero, and a good mirror surface was obtained.

Furthermore, as the magnetic polishing liquid 4, a composition in which the ferrite powder was changed to NiCuZn ferrite was also prepared, and the sample was polished and evaluated. That is, the magnetic polishing liquid 4 was made with each component having a wt% shown in Table 9, and NiCuZn ferrite having a saturation magnetic flux density of about 300 mT at room temperature was used.

When the object to be polished was polished, the results shown in Table 10 were obtained.

  As can be seen from Table 10, in the case of NiCuZn ferrite, even when the average particle diameter is set to 100 μm as in the case of MnZn ferrite, polishing is not possible with Sample 21 to which no iron powder is added or Sample 22 to which only a small amount is added. Thus, polishing can be performed by mixing a certain amount of iron powder. This indicates that NiCuZn ferrite has a lower saturation magnetic flux density than MnZn ferrite, and that the magnetic flux density was insufficient even when the average particle size was increased, and that it was necessary to increase the magnetic flux density by adding iron powder. confirmed. Further, when the average particle diameter of the ferrite particles is set to 220 μm, scratches start to be generated like the MnZn ferrite.

  In Samples 21 to 24, the ferrite particles were not those obtained by pulverizing the sintered body lump, but those obtained by firing the pellets as they were, but it was confirmed that the polishing power was weak. It can be said that when the pellets are fired as they are, the sintered body remains in a spherical shape, and therefore the ferrite particles have no corners, so that the polishing power is reduced. Therefore, it is preferable that the ferrite particles have corner portions (preferably sharp corner portions).

It is explanatory drawing which shows the conventional magnetic polishing typically. 1 is a side view showing a preferred embodiment of the present invention. It is explanatory drawing which shows typically the magnetic polishing liquid (paste material) which concerns on this invention. It is a graph which shows an experimental result. It is a graph which shows an experimental result. It is a graph which shows an experimental result. It is a graph which shows an experimental result. It is a graph which shows an experimental result. It is a graph which shows an experimental result.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polishing object 2 Polishing tool 20 Permanent magnet 3 Y-axis stage 4 Magnetic polishing liquid (paste material)
41 Magnetic particles 42 Non-magnetic particles 44 Solvent 45 Abrasive particles (treated particles)
5 Drive means

Claims (13)

In order to perform surface treatment, it is a paste material that exists in the vicinity of a magnetic field generation source facing non-contact with an object to be processed and is interlocked by the action of a magnetic field,
A paste material comprising at least magnetic particles for forming magnetic clusters, treated particles having magnetism, and a solvent. The paste material according to claim 1, wherein the treated particles are ferrite particles. 2. The paste material according to claim 1, wherein the treated particles are ferrite particles obtained by sintering a sintered compact of a raw material granulated powder with mechanical force. The paste material according to any one of claims 1 to 3, wherein the treated particles have a saturation magnetization of 100 mT or more. The paste material according to any one of claims 1 to 4, wherein the magnetic particles are formed from a magnetic material having a saturation magnetization of 7 kG or more in volume magnetization.   The paste material according to any one of claims 1 to 5, wherein the solvent is water and the magnetic particles are cobalt.   The paste material according to any one of claims 1 to 5, wherein the solvent is an organic solvent, and the magnetic particles are iron.   The paste material according to any one of claims 1 to 5, wherein the solvent is oil and fat, and the magnetic particles are iron.   The paste material according to any one of claims 1 to 8, wherein the magnetic particles are non-spherical particles.   The paste material according to any one of claims 1 to 8, wherein a low melting point resin insoluble in the solvent is uniformly mixed in the solvent.   The paste material according to claim 10, wherein the solvent is vegetable oil.   The paste material according to claim 10 or 11, wherein the low melting point resin has a melting point of 40 ° C or higher and 80 ° C or lower.   The paste material according to any one of claims 10 to 12, wherein the treated particles have a shape having corners.

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