KR100697682B1 - Cerium-based polishing material - Google Patents

Abstract

An object of the present invention is to provide a cerium-based abrasive having a higher polishing rate and less occurrence of scratches. The cerium-based abrasive according to the present invention is a cerium-based abrasive composed mainly of rare earth oxides containing at least cerium, lanthanum, praseodymium, and neodymium as fluorine and rare earth elements. The content (Nd ₂ O ₃ / TREO) of the content is a cerium-based abrasive having 0.001% to 5% by weight. When the polishing target surface such as glass is polished using the abrasive, the polishing can be performed in a shorter time as compared with the case of using a conventional cerium-based abrasive. Moreover, the flaw generation in the polishing surface obtained by polishing can be suppressed more reliably.

Cerium abrasives, fluorine, rare earth oxides, cerium, lanthanum, praseodymium, neodymium.

Description

Cerium-based abrasives {CERIUM-BASED POLISHING MATERIAL}

The present invention relates to a so-called cerium-based abrasive having a cerium oxide as a main component.

Cerium-based abrasives are produced, for example, by grinding, roasting, and classifying raw materials, such as bastnaesite concentrates, which contain abundant rare earth elements, including cerium, and classifying as necessary. do. The manufactured cerium-based abrasives include cerium oxide (CeO ₂ or the like) as a main component (see, for example, Japanese Unexamined Patent Application Publication No. Hei 1-266183). In addition, cerium oxide (La ₂ O _3, etc.) Oxides of other rare earth elements are contained. In addition, there is a cerium-based abrasive containing fluorine (F) as an abrasive having a higher polishing rate (see, for example, Japanese Unexamined Patent Publication No. 2002-097457).

By the way, as an abrasive | polishing material, it is calculated | required to be excellent in polishing force as possible, and to obtain a polishing surface as smooth as possible after grinding | polishing. The polishing force is, for example, represented by the height of the polishing rate. That is, as an abrasive, what has a higher polishing rate is calculated | required. Moreover, as an abrasive | polishing material from which a smooth grinding | polishing surface is obtained, what is hard to generate | occur | produce a flaw in a grinding | polishing surface is calculated | required.

By the way, conventional cerium-based abrasives containing abrasives containing fluorine do not necessarily have satisfactory performance in terms of polishing speed and flaw generation. For example, there is a field in which the demand for cerium-based abrasives increases, and there are fields for manufacturing precision instruments, electronic devices, or such components. There is a need for an abrasive that is less likely to cause scratches.

Disclosure of the Invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide a cerium-based abrasive having a higher polishing rate and less occurrence of scratches.

The inventors of the present invention have repeatedly studied the polishing rate and flaw generation of cerium-based abrasives, and when the content rate of neodymium oxide is set to a predetermined ratio, the polishing rate of cerium-based abrasives becomes higher and the flaws are less likely to occur. To the present invention.

The present invention relates to all rare earth oxides in cerium-based abrasives having a rare earth oxide as a main component containing fluorine (F) and at least cerium (Ce), lanthanum (La), praseodymium (Pr), and neodymium (Nd) as rare earth elements. It is a cerium-based abrasive material having a ratio of weight of neodymium oxide (Nd ₂ O ₃ / TREO) to 0.001% by weight to 5% by weight (hereinafter referred to as "TREO"). In addition, "TREO" is the total weight of the weight of each rare earth element contained in the object as a rare earth oxide (calculated), and can be obtained by analyzing and calculating the composition of the target material. In addition, when the composition of the target substance is not known, TREO performs pretreatment such as dissolution and dilution on the sample, if necessary, and then precipitates all rare earth elements as oxalate, and then filtration, drying and roasting. After obtaining a rare earth oxide, it can obtain | require by the method of measuring mass.

For example, in the conventional cerium-based abrasive described in Patent Document 1 (Japanese Patent Laid-Open No. Hei 1-266183), the ratio of weight of neodymium oxide (hereinafter referred to as "content") in TREO is about 9%. In contrast, the content of neodymium oxide in the cerium-based abrasive according to the present invention is considerably low. As a result of the investigation, it has been found that the cerium-based abrasive having a ratio of the weight of neodymium oxide in TREO in the above range has a higher polishing rate and is less likely to cause scratches. Therefore, when the polishing target surface such as glass is polished using the abrasive according to the present invention, polishing can be performed in a shorter time as compared with the case of using a conventional cerium-based abrasive. In addition, the occurrence of scratches on the polishing surface obtained by polishing can be more surely suppressed. As described above, in the cerium-based abrasive of the present invention, the range of the weight ratio (Nd ₂ O ₃ / TREO) of neodymium oxide to TREO is 0.001 wt% or more and 5 wt% or less. This is because scratches tend to occur at less than 0.001% by weight. On the other hand, if it exceeds 5% by weight, the polishing rate is low, and polishing scratches also tend to occur. In addition, in order to obtain higher performance for both the polishing rate and the polishing defect, the weight ratio (Nd ₂ O ₃ / TREO) of the neodymium oxide to TREO is preferably 2% by weight or less, and 0.5% by weight or less. Is more preferable, and 0.1 weight% or less is still more preferable.

In addition, the cerium-based abrasive is roughly pulverized raw materials such as vastene concentrate and rare earth carbonate or rare earth oxide mainly composed of cerium, and subjected to wet treatment such as mine treatment or fluorination treatment, if necessary, and roasted. It is manufactured by classifying as needed. In addition, as a raw material of the cerium-based abrasive according to the present invention, rare earth concentrates such as bastsite concentrate, monazite concentrate and Chinese complex concentrate, for example, the following series of treatments, namely After the treatment such as sulfuric acid treatment, alkali treatment, fractionation precipitation treatment or fractional dissolution treatment to obtain a rare earth solution in which impurities other than rare earth elements are reduced, the solution obtained by separating and purifying the solution by solvent extraction V) a rare neodymium rare earth compound obtained by mixing a neodymium rare earth solution (refined liquid) with a precipitant such as ammonium hydrogen carbonate or ammonia water to produce a precipitate, and performing a series of treatments for separating the precipitate by filtration or the like (e.g., For example, a rare earth carbonate or its roasted material (for example, a rare earth oxide) is preferable. In addition, Nd in rare earth solution (purified liquid) is separated and purified by extraction conventional solvent ₂ O ₃ / TREO is usually 10 but more than% by weight, and the cerium-based abrasive material which is the value of the Nd ₂ O ₃ / TREO predetermined range as in the present invention In solvent extraction when refining a raw material of a dragon, the reduction of rare earths on the heavy rare earth side is enhanced than that of neodymium or neodymium, and the low neodymium rare earth solution (for example, Nd ₂ O ₃ / TREO is 5% by weight or less). It is more preferable to obtain).

In addition, as the cerium-based abrasive according to the present invention, it is preferable that the proportion of the total weight of rare earth oxides of cerium, lanthanum, praseodymium and neodymium, occupied by TREO is 97% by weight or more. This is because a high polishing rate and a flaw prevention effect can be more reliably obtained. In addition, since these effects are more reliably obtained, the value of the ratio is more preferably 98% by weight or more, and even more preferably 99% by weight or more.

The preferred content of each of rare earth oxide, is described for each rare-earth oxide, the weight ratio of cerium oxide occupied in TREO (CeO ₂ / TREO) of the TREO is preferably 50 wt% to 90 wt%. It is because cerium oxide is the substance which has the most grinding | polishing effect | action of all rare earth oxides, and when this weight ratio is less than a lower limit, sufficient polishing rate cannot be obtained. On the other hand, if it is going to exceed the upper limit, it is necessary to sufficiently reduce the lanthanum in the raw material refining step, such as trouble and cost, resulting in poor productivity. In this regard, the weight ratio of cerium oxide in TREO is more preferably 55% by weight to 85% by weight, and even more preferably 60% by weight to 80% by weight.

The weight ratio of lanthanum oxide occupied in _{TREO (La 2 O 3 / TREO} ) is preferably from 2 wt% to 45 wt%. It is considered that lanthanum oxide is the most fluorine-retaining substance among all rare earth oxides, and is present in rare earth oxides mainly composed of cerium, or present in cerium-based abrasives in the form of oxyfluorides (LaOF or CeLa ₂ O ₃ F ₃ ). I think. In addition, the fluorine component held by lanthanum oxyfluoride (LaOF) or the like has an effect of gradually releasing fluoride ions during polishing, particularly during glass polishing, to promote chemical action, and to increase the polishing rate. By the way, when the ratio of the weight of lanthanum oxide to TREO is less than the above lower limit, the effect of mildening the chemical action becomes low, and the polishing surface obtained by polishing becomes a rough surface. On the other hand, when the upper limit is exceeded, a sufficient polishing rate cannot be obtained. In this regard, the weight ratio of lanthanum oxide to TREO is more preferably 5% by weight to 40% by weight, and even more preferably 10% by weight to 37.5% by weight. In addition, the weight ratio (Pr ₆ O ₁₁ / TREO) of praseodymium oxide in TREO is preferably from 0.1% by weight to 10% by weight, more preferably from 1% by weight to 8% by weight.

In addition, the content of fluorine in the cerium-based abrasive is preferably 0.5% by weight to 10% by weight. This is because a sufficient polishing rate may not be obtained below the lower limit, and if it exceeds the upper limit, polishing flaws tend to occur. Further, from the viewpoint of obtaining a higher effect on both the polishing rate and the polishing flaw, the content of fluorine is more preferably 1% by weight to 8% by weight, even more preferably 2% by weight to 7% by weight.

In addition, the molar ratio (F / (La + Pr)) of fluorine (F) and lanthanum (La) and praseodymium (Pr) contained in the cerium-based abrasive are preferably 0.2 to 3. It is because a hydroxide is easy to produce | generate below a lower limit at the time of cerium-type abrasive storage, grinding | polishing, especially at the time of grinding | polishing. The abrasive in the state where hydroxide is produced has the inconvenience of low polishing rate (polishing power). In addition, when hydroxide easily forms during polishing, the polishing rate is low in a short time from the start of polishing. On the other hand, the abrasive | polishing agent whose said molar ratio exceeded the upper limit has the inconvenience that the chemical action of fluorine at the time of grinding | polishing is too strong, and the grinding | polishing surface obtained after grinding | polishing will become rough.

Moreover, when X-ray peak intensity was measured by the X-ray diffraction method which used Cu-K (alpha) ray or Cu-K (alpha) ₁ line as an X-ray source, about the rare earth oxy fluoride which appears in the range of 2 (theta) = 20deg-30deg. More preferred is a cerium-based abrasive having an intensity ratio (rare earth oxyfluoride / cerium oxide) of the strongest X-ray peak intensity among the X-ray peak intensities and the strongest X-ray peak intensity among the X-ray peak intensities with respect to cerium oxide. Do. In addition, as said rare earth oxy fluoride (LnOF), lanthanum oxy fluoride (LaOF) etc. are mentioned, for example. In addition, the X-ray peak intensity of cerium oxide here is more specifically the diffraction X-ray peak intensity of the cubic rare earth oxide (Ln _x O _y ) which has cerium as a main component. Ln _x O _y is usually 1.5 ≦ _y / X ≦ 2, and is identified as, for example, CeO ₂ , Ce _0.5 Nd _0.5 O _1.75 or Ce _0.575 Nd _0.225 O _1.875 . However, even when the Nd ₂ O ₃ / TREO is small, in the abrasive having a large Ln ₂ O ₃ / TREO, Ln _x O _y is a Ce-Nd-O-based compound (Ce _0.5 Nd _0.5 O _1.75 or Ce _O.75). Nd _O.25 O _1.875 ). In this case, it is assumed that Ln _x O _y identified as a Ce-Nd-O-based compound is an oxide which also contains rare earth elements (La and the like) other than Ce and Nd. It is because it was found that when the said intensity | strength ratio is less than a lower limit, orange peel which adversely affects grinding | polishing is easy to generate | occur | produce, and it is not preferable. Moreover, when an intensity | strength ratio exceeds an upper limit, polishing speed will fall. In this respect, the strength ratio is more preferably 0.1 to 0.5, and even more preferably 0.2 to 0.4.

Incidentally, the X-ray diffraction measurement is performed by injecting a characteristic X-ray as described above into a sample (cerium-based abrasive) and diffracting the detector (counter tube or semiconductor detector) along the circumference of the sample. The intensity of one X-ray is measured, the obtained X-ray diffraction intensity curve is analyzed, and the substance is identified. For example, when a Cu-Kα ray or a Cu-Kα ₁ line is used as the X-ray source, the maximum diffraction X-ray peak intensity for the rare earth oxyfluoride in the range of 20deg to 3deg is usually 26.5. It appears in the range of deg ± 0.5 deg, and the maximum X-ray peak intensity for cerium oxide (CeO ₂ ) in the same range is in the range of 28.1 deg ± 1.Odeg.

The X-ray peak intensity for the rare earth fluoride, which is the maximum peak in the range of 2θ (diffraction angle) = 24.2 ± 0.5 deg, among the diffraction X-ray peak intensities measured by the X-ray diffraction measurement method, and the X-ray for CeO ₂ . It is preferable that the intensity ratio (LnF ₃ / CeO ₂ ) of the strongest X-ray peak intensity among the peak intensities is less than 0.14. When the said strength ratio is more than that, it is easy to produce many polishing flaws. Also, as the rare earth fluoride (LnF ₃₎ used herein, for example, there may be mentioned lanthanum fluoride (LaF _3). In addition, although the maximum peak for the rare earth fluoride in the diffraction angle 2θ in the range of 20 deg to 30 deg appears at a position close to the maximum peak of cerium oxide but not in the range of 24.2 ± 0.5 deg, the influence of the maximum peak of cerium oxide As a result, it may be difficult to accurately determine the strength and the like of the maximum peak of the rare earth fluoride. Therefore, in the present invention, the rare earth fluoride uses a maximum peak in the range of 24.2 ± 0.5 deg.

As targets to be used in the X-ray diffraction measurement, use of molybdenum (Mo), iron (Fe), cobalt (Co), tungsten (W), silver (Ag) and the like can be considered as well as copper (Cu). A copper (Cu) target is preferable from the point that a large peak intensity can be obtained and more accurate measurement can be performed.

The pore volume of the cerium-based abrasive material is O.OO2cm ³ /g~O.1cm ³ / g are preferred, more preferably O.OO5cm ³ /g~O.O8cm ³ / g. If the polishing rate is lower than the lower limit, polishing scratches are likely to occur. If the upper limit is exceeded, the polishing rate is too low, and a sufficient polishing rate is not obtained.

As described above, the cerium-based abrasive according to the present invention has a higher polishing rate and less occurrence of scratches. Therefore, by using this to polish the surface to be polished, such as glass, polishing can be performed in a shorter time as compared with the case of using a conventional cerium-based abrasive, and the occurrence of scratches on the polishing surface can be more surely suppressed. .

Best Mode for Carrying Out the Invention

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of the cerium type abrasive | polishing material by this invention is described.

First embodiment

First, high purity cerium oxide (CeO ₂ ), lanthanum oxide (La ₂ O ₃ ), praseodymium oxide (Pr ₆ O ₁₁ ), neodymium oxide (Nd ₂ O ₃ ), and samarium oxide (Sm ₂ O ₃ ), respectively, at 850 ° C. The calcined product was prepared under conditions of roasting for 24 hours at. The content rate of impurities other than the rare earth oxide in each prepared rare earth oxide was less than 0.1%. In addition, in any rare earth oxide, the purity (ratio of the weight of the target rare earth oxide in TREO) is 99.99% by weight or more, and the ratio of the weight of neodymium in TREO in each rare earth oxide except neodymium oxide in the prepared rare earth oxide (Nd ₂ O ₃ / TREO) was less than 0.001%. In addition, the content rate of fluorine (F) was less than 0.001 weight%. 100 kg of the raw materials which weighed and mixed these rare earth oxides in suitable quantities were prepared. As described above, in the present embodiment, raw materials were manufactured by mixing rare earth oxides of high purity in order to evaluate the polishing performance and the like of various cerium-based abrasives having different content rates such as cerium oxide, lanthanum oxide, praseodymium oxide, and neodymium oxide. . Since the content rate of each rare earth oxide in a raw material may be considered to be the same as the weight ratio of each rare earth oxide in TREO in the abrasive manufactured, the display was abbreviate | omitted (refer Table 1). In Comparative Example 1, neodymium oxide was not mixed in the raw materials. In addition, in Examples 6 to 8 of Table 1 (CeO ₂ + La ₂ O ₃ + Pr ₆ O ₁₁ + Nd ₂ O ₃ ) / TREO (four types), the raw material was not 100%, but this was samarium oxide in the raw material. This means that it is mixed.

The obtained raw material (mixture of rare earth oxides) and pure water twice the weight of the raw material weight were mixed and wet-pulverized with an attritor to obtain a slurry. In the attritor, a stainless ball having a diameter of 5 mm was used as the grinding medium. In addition, the grinding time was 8 hours.

Next, 10% hydrofluoric acid was added to the obtained slurry, the weight ratio (F / (TREO + F)) of the fluorine component in the slurry was adjusted, and the slurry was stirred for 30 minutes (fluorination treatment). . In addition, in each Example except Example 12, 13 and each comparative example except Comparative Examples 5 and 6, it adjusted so that the weight ratio (F / (TREO + F)) of a fluorine component might be set to 6%. In addition, the weight ratio of the fluorine component was adjusted to 1.5% in Example 12, 10% in Example 13, and 15% in Comparative Example 6, respectively. In Comparative Example 5, the fluorination treatment was not performed.

Then, what was called repulp washing | cleaning which settled solid content, extract | eliminated supernatant liquid, and added pure water was performed, and the slurry after washing was filtered by the filter press method. And the filter cake obtained was dried at 140 degreeC for 48 hours. Furthermore, the obtained dry cake was pulverized by the roll crusher, and the obtained crushed product was roasted at 950 degreeC for 18 hours. This roasted product was pulverized with a sample mill, and the obtained pulverized product was classified with a turbo crusher (classifying point was set to 3 µm) to obtain a cerium-based abrasive. Table 1 shows the ratio of the weight of each rare earth oxide in TREO in the obtained cerium-based abrasive.

Measurement of fluorine concentration

About the cerium type abrasive | polishing material obtained by each Example and the comparative example, the fluorine content rate was measured. An alkali melting, hot water extraction, and fluorine ion electrode method were used for fluorine analysis except for the abrasive obtained in Comparative Example 5 for the measurement of the fluorine concentration. In addition, the thermal hydrolysis lanthanum alizarin complexone absorbance photometric method was used for the measurement of the fluorine concentration of the abrasive obtained by the comparative example 5. The measurement result is as showing to each table | surface.

Polishing test

The polishing test was carried out using the cerium-based abrasives obtained in the examples and the comparative examples, and the polishing rate, the flaw evaluation of the obtained polishing surface, and the washability evaluation were performed. Evaluation results are as showing to each table | surface.

First, a powdered cerium-based abrasive powder and pure water were mixed to prepare an abrasive slurry having a solid content concentration of 15% by weight. Using this abrasive slurry, the surface of the glass for flat panels of 65 mm (phi) was polished by the polishing test machine (HSP-2I type | mold, the Daido Seiji Co., Ltd. product). And after completion | finish of grinding | polishing, the glass for flat panel was wash | cleaned with pure water, and it dried in the state without a particle. In addition, this polishing test machine polishes a polishing target surface with a polishing pad while supplying an abrasive slurry to the polishing target surface, and uses a polyurethane product as the polishing pad. The pressure of the polishing pad on the polishing surface was 5.9 kPa (60 g / cm ² ). In addition, the rotational speed of the polishing tester was set to 100 rpm. In addition, the supply amount of the abrasive slurry was 5 liters / min.

Evaluation of Polishing Speed

The weight of glass before and after polishing was measured to determine the amount of reduction in glass weight due to polishing, and the polishing value was determined based on this value. In this polishing test, the polishing rate was evaluated using this polishing value. In addition, the grinding | polishing value at the time of grind | polishing using the abrasive | polishing material obtained by the comparative example 3 was made into the reference | standard (100) here.

Evaluation of Abrasive Flaw

Moreover, after completion | finish of grinding | polishing, the flaw evaluation was performed with respect to the polished surface which wash | cleaned with pure water and dried in the state which was not dusty. The flaw evaluation was performed by observing a glass surface by the reflection method using a 300,000 lux halogen lamp as a light source, scoring the number of a large flaw and a fine flaw, and deducting by making 100 points into perfect scores. In this flaw evaluation, the grinding | polishing precision calculated | required by the final grinding | polishing of the glass substrate for hard disks or LCD was made into the criterion of determination. Specifically, in Tables 1 to 4, "◎" is 98 or more (very suitable for finishing polishing of the glass substrate for HD and LCD), and "(circle)" is less than 98 and 95 or more (HD and LCD). "△" is less than 95 points and 90 points or more (it can be used for finishing polishing of the glass substrate for HD and LCD), and "x" is less than 90 points It cannot be used for the final polishing of the glass substrate for molten / LCD.

Detergency Evaluation

Moreover, the test was done about the washability of an abrasive. In the detergency evaluation, first, the slide glass for observing the cleaned and dried optical microscope was immersed in the abrasive slurry, pulled up and dried once at 50 ° C, and then immersed in a container containing pure water, and ultrasonic cleaning was performed. It carried out for a minute, and after the ultrasonic washing, the slide glass taken out from the container was poured with pure water and washed, and the slide glass of the observation object was obtained. Then, washability was evaluated by observing the amount of residual abrasive particles remaining on the slide glass surface with an optical microscope. Specifically, in Tables 1 to 4, "(circle)" is very suitable for finishing polishing without the residual of abrasive grains being observed, and "(triangle | delta)" is a thing which is suitable for finishing polishing, although "(triangle | delta)" is small but the residual of abrasive grain was observed, "X" shows that the residual of abrasive grain is very much observed, and is unsuitable for finish polishing.

TABLE 1

* 1) Ratio of fluorine element weight to abrasive weight.

* 2) The ratio of TREO equivalent weight to the abrasive weight.

Examples 1 to 5 and abrasives of Comparative Examples 1 to 3 As shown in Table 1, respectively, different from the ratio of the weight of neodymium oxide (Nd ₂ O ₃₎ in TREO. Among these, the abrasives of Examples 1 to 5 had a high polishing rate and hardly generated polishing defects. On the other hand, although the abrasive | polishing material of the comparative example 1 which did not mix neodymium oxide had a high polishing rate, a flaw was easy to generate | occur | produce. Moreover, the abrasive | polishing material of the comparative example 2 and the comparative example 3 in which the ratio of the weight of the neodymium oxide in TREO exceeds 5 weight% had a low grinding | polishing rate, and the polishing flaw was easy to generate | occur | produce. As a result, it was found that, in the cerium-based abrasive, the ratio (Nd ₂ O ₃ / TREO) of the weight of neodymium oxide to TREO is preferably from 0.01% by weight to 5% by weight. In addition, as can be seen by comparing each example with respect to the polishing rate, the weight ratio of neodymium in TREO is preferably 2% by weight or less, more preferably 0.5% by weight or less, even more preferably 0.1% by weight or less. Turned out.

In addition, the abrasives of Examples 6 to 8 each contain the tetraoxide “cerium oxide (CeO ₂ ), lanthanum oxide (La ₂ O ₃ ), praseodymium oxide (Pr ₆ O ₁₁ ), and neodymium oxide (Nd ₂ O ₃ ), which occupy TREO. The ratio of the total weight of the ") is 100% by weight or less, and each content rate, which is the value of the ratio, is different for each example. As can be seen from Examples 1 to 8 including these examples, when the ratio of the total weight was 96% by weight, the polishing rate required as the abrasive was ensured, and the occurrence of polishing defects could also be prevented. In addition, it was found that when the total content is 97% by weight or more, a higher polishing rate is ensured and the occurrence of scratches is more reliably prevented.

Example 4 and Example 10 are not only suitable for the ratio of neodymium oxide (Nd ₂ O ₃ / TREO) to TREO, but also for CeO ₂ / TREO, La ₂ O ₃ / TREO, and Pr ₆ O _1l / TREO. It is a value, a polishing rate is high, a polishing flaw hardly generate | occur | produced, and the remainder of the abrasive was not observed, either. In contrast, in Example 9 and Example 11, Nd ₂ O ₃ / TREO is a suitable value, but at least one of CeO ₂ / TREO, La ₂ O ₃ / TREO, Pr ₆ O ₁₁ / TREO is not a suitable value, At least one of the polishing rate, the polishing flaw, and the cleaning property was inferior to Example 4 or Example 10. However, Nd ₂ O ₃ / TREO was superior to Comparative Examples 1 to 3, which was not a suitable value. Since the abrasive of Comparative Example 4 did not contain praseodymium at all, and Pr ₆ O ₁₁ / TREO was not a suitable value, the polishing performance was inferior to that of Example 5.

Based on the fluorine content in the cerium-based abrasive and the molar amount (mol / L) per 1 kg of the rare earth abrasive, the molar ratio (F / (La + Pr)) of the fluorine content in the cerium-based abrasive and the total content of lanthanum and praseodymium was calculated. . The calculated value is shown in Table 2. The cerium-based abrasives of the examples and comparative examples shown in Table 2 were 65.0 wt% CeO ₂ / TREO, 30.9 wt% La ₂ O ₃ / TREO, 4.0 wt% Pr ₆ O ₁₁ / TREO, and Nd. ₂ O ₃ / TREO is 0.1% by weight.

TABLE 2

* 1) Ratio of fluorine element weight to abrasive weight.

* 2) Ratio of TREO equivalent weight to abrasive weight.

As shown in Table 2, the abrasives of Examples 2, 12 and 13 and Comparative Examples 5 and 6 differ in content of fluorine (F) in the abrasives, respectively. Among these, the abrasives of Examples 2, 12, and 13 were high in polishing rate, hardly to generate polishing defects, and were good. On the other hand, the polishing material of Comparative Example 5 containing almost no fluorine had a significantly low polishing rate. Moreover, although the abrasive | polishing material of the comparative example 6 with a high content of fluorine had a high polishing rate, polishing defects were easy to generate | occur | produce. As a result, it was found that the content of fluorine in the cerium-based abrasive is preferably 0.5% by weight to 10% by weight. In addition, it was found that the content of fluorine is even more preferable from 2% by weight to 7% by weight, because higher effects are obtained for both the polishing rate and the polishing flaw. Moreover, as for the molar ratio (F / (La + Pr)) of the content rate of fluorine and the total content rate of lanthanum and praseodymium, 0.2-3 were preferable.

Second embodiment

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the cerium-based abrasive material according to the present invention, which is produced using a raw material different from the raw material used in the first embodiment, will be described.

First, a rare earth carbonate (made in China) containing cerium as a main component was prepared. The rare earth carbonate had a TREO of 52.3% by weight, 52.1% of CeO ₂ / TREO, 26.7% of La ₂ O ₃ / TREO, 7.2% of Pr ₆ O ₁₁ / TREO, and 13.0% of Nd ₂ O ₃ / TREO. . In Examples 14-17 and Comparative Examples 7-10 (refer to Table 3 and Table 4 published later) of this embodiment, in the comparative example 7, this rare-earth carbonate was used as a raw material as it was. In Examples 14 to 17 and Comparative Examples 8 to 10, the rare earth carbonate was dissolved in hydrochloric acid, and the obtained carbonate solution was separated and purified by a solvent extraction method to obtain a rare earth solution (refining solution) having reduced neodymium and lanthanum. , to a mixture of the obtained rare earth solution with ammonium bicarbonate solution (precipitation agent), filtered, washed with water and then precipitation of the rare earth carbonate, using a centrifugal separator, the rare earth carbonates used as a raw material (Nd ₂ O ₃ / TREO is 0.1 % To 6.3 wt%).

Here, the outline of the solvent extraction of this embodiment is demonstrated. In the solvent extraction, as an organic solvent, an extractant (PC-88A: manufactured by Daihachi Chemical Co., Ltd.) and a diluent (ifsol: manufactured by Idemitsu Seki Yugaku Co., Ltd.) are used in a liquid ratio (extractant / diluent). ) Was used at a ratio of 1/2. Then, the organic solvent and the carbonate solution (TREO 240 g / L) are countercurrent multistage contacts (30 steps) in a state in which the flow ratio (organic solvent / carbonate solution) is 8/1. Extracted. At this time, in Example 16, a part of lanthanum was left in aqueous solution. In Examples and Comparative Examples other than this, almost all of the rare earth elements were extracted with an organic solvent. Adjustment of extraction was performed by changing the addition flow volume of the sodium hydroxide aqueous solution added in the middle of countercurrent multistage extraction. Thereafter, the organic solvent containing the rare earth element and the aqueous solution of 3 mol / L hydrochloric acid are subjected to countercurrent multi-stage contact (30 steps), and rare earth elements (heavy earth from samarium and more easily extractable with organic solvents than neodymium and neodymium) Most of yttrium (Y)) was left in an organic solvent, and most of lanthanum, cerium, praseodymium, and part of neodymium were extracted into an aqueous hydrochloric acid solution to obtain a purified solution. In addition, adjustment of the extraction amount was performed by changing the flow volume of the hydrochloric acid aqueous solution (flow rate of an organic solvent is fixed).

The cerium-based abrasive was produced from the obtained raw material (rare earth carbonate) using the same process as in the first embodiment. As can be seen from the above description, the raw material of the second embodiment has a lower ratio of TREO of the raw material to the total weight of the raw material than the raw material of the first embodiment, but the second embodiment also has the first embodiment. As described above, the mixture obtained by mixing pure water and raw material twice the weight of the raw material was wet-pulverized with an attritor to obtain a slurry. The wet grinding time by the attritor was 10 hours. Moreover, in the fluorination process which adds 10% hydrofluoric acid to the slurry obtained by wet grinding, it adjusted so that the weight ratio (F / (TREO + F)) of the fluorine component in a slurry might be set to 7%. In addition, the roasting temperature in a roasting process was 950 degreeC like Example 1 except for Example 17, 18 and Comparative Examples 9 and 10. Among these, roasting temperature was 650 degreeC in the comparative example 9, 750 degreeC in Example 17, 1100 degreeC in Example 18, and 1200 degreeC in the comparative example 10. The abrasive production conditions other than these were the same as that of 1st Embodiment. Therefore, the description of the abrasive manufacturing process is omitted here.

TABLE 3

* 1) Ratio of fluorine element weight to abrasive weight.

* 2) Ratio of TREO equivalent weight to abrasive weight.

Although the Nd ₂ O ₃ / TREO of the rare earth carbonate (made in China), which is the original raw material of the second embodiment, exceeds 5%, the abrasive of Examples 14 to 16 (Nd ₂ O ₃ / TREO) having reduced neodymium by solvent extraction is 5% or less), high polishing performance was obtained. On the other hand, the Nd ₂ O ₃ / TREO is more than 5% Comparative Example 7, the abrasive is a polishing rate of 8 compared to the embodiment of the abrasive, blemish assessment and detergency were poor.

Further, the diffracted X-ray intensity with respect to the production of cerium-based abrasive material (Intensity), the average particle diameter (D _50), was measured in the pore volume.

X-ray diffraction measurement

Using an X-ray diffractometer (manufactured by McScience Co., Ltd., MXP18), an X-ray diffraction analysis was performed on a cerium-based abrasive to measure diffraction X-ray intensity. In this measurement, the copper (Cu) target was used and the diffraction angle (2 (theta)) of the diffraction X-ray pattern by the Cu-K (alpha) ₁ line obtained by irradiating a Cu-K (alpha) line was analyzed about the peak in 20deg-30deg. In addition, other measurement conditions were a pipe voltage of 40 kV, a pipe current of 150 mA, a measurement range of 2θ = 5 to 80 deg, a sampling width of 0.02 deg, and a scanning speed of 4 deg / min. In addition, the X-ray peak intensity and lanthanum fluoride (LaF) of lanthanum oxyfluoride (LaOF) with respect to the X-ray peak intensity of cerium oxide (CeO ₂ ) read from the X-ray diffraction measurement results of the cerium-based abrasives of the Examples and Comparative Examples. Table 4 shows data of the ratio of X-ray peak intensities of ₃ ).

Average particle size (D ₅₀ ) Measurement

The particle size distribution of a cerium-based abrasive is measured using a laser diffraction and scattering method particle size distribution measuring device (manufactured by Shimadzu Corporation, SALD-200OA), and the average particle diameter (D ₅₀ : from the small particle size side). Particle size at 50% cumulative volume).

Measurement of pore volume

The pore volume of the cerium-based abrasive was measured using a pore volume measuring device (COULTER SA3100).

TABLE 4

* 1) Ratio of fluorine element weight to abrasive weight.

* 2) Ratio of TREO equivalent weight to abrasive weight.

Among the abrasives of the examples and comparative examples shown in Table 4, the abrasives of the examples in which the strength ratio (LaOF / CeO ₂ ) of the X-ray peak intensity is 0.05 to 0.6 are high in polishing rate and hardly to generate polishing defects. Was. On the other hand, the polishing material of Comparative Example 9 having a small strength ratio (LaOF / CeO ₂ ) was significantly low in polishing rate and flaws occurred. Moreover, although the abrasive | polishing material of the comparative example 10 with a large intensity ratio had the high grinding | polishing rate, the flaw remarkably occurred. As a result, it was found that an abrasive having an intensity ratio (LaOF / CeO ₂ ) of X-ray peak intensity of 0.05 to 0.6 is preferable.

Further, in the pore volume of O.OO2cm ³ /g~O.1cm ³ / g Example abrasives, a high polishing rate, and was good also difficult to polish scratches occur. On the other hand, the abrasive | polishing material of the comparative example 9 with a large pore volume was remarkably low polishing rate. Moreover, the flaw generate | occur | produced the abrasive of the comparative example 10 with small pore volume. As a result, the pore volume was found to also have the abrasive O.OO2cm ³ /g~O.1cm ³ / g preferably.

The cerium-based abrasive according to the present invention has a higher polishing rate and less occurrence of scratches. By using this, polishing the surface to be polished, such as glass, polishing can be performed in a shorter time as compared with the case of using a conventional cerium-based abrasive, and the occurrence of scratches on the polishing surface can be more surely suppressed. Therefore, it is suitable for uses, such as surface grinding of precision instruments, an electronic apparatus, or such components.

Claims (7)

In a cerium-based abrasive having a rare earth oxide as a main component, which contains at least cerium (Ce), lanthanum (La), praseodymium (Pr), and neodymium (Nd) as fluorine (F) and rare earth elements, The ratio of the weight of neodymium oxide (Nd ₂ O ₃ / TREO) to the total rare earth oxide weight (TREO) is 0.001% to 0.5% by weight, Pores (細孔) volume is a ³ / g 0.002cm ³ /g~0.1cm Cerium-based abrasives. The method of claim 1, A cerium-based abrasive having a ratio of the total weight of the rare earth oxides of cerium, lanthanum, praseodymium, and neodymium, which accounts for the total weight of the rare earth oxide. The method according to claim 1 or 2, The ratio of the weight of cerium oxide (CeO ₂ / TREO) to the total weight of the rare earth oxides is 50% to 90% by weight, The ratio of the weight of lanthanum oxide (La ₂ O ₃ / TREO) to the total weight of the rare earth oxides is 2% by weight to 45% by weight, A cerium-based abrasive having a weight ratio of praseodymium oxide (Pr ₆ O ₁₁ / TREO) to 0.1 weight% to 10 weight% in terms of the total rare earth oxide weight. The method according to claim 1 or 2, A cerium-based abrasive having a fluorine content of 0.5% by weight to 10% by weight. The method according to claim 1 or 2, The molar ratio (F / (La + Pr)) of fluorine (F) contained and lanthanum (La) and praseodymium (Pr) contained is 0.2-3 cerium-based abrasives. The method according to claim 1 or 2, X-ray to rare earth oxyfluoride, which appears in the range of 2θ (diffraction angle) = 20 deg to 30 deg when X-ray peak intensity is measured by X-ray diffraction method using Cu-Kα ray or Cu-Kα ₁ line as X-ray source A cerium-based abrasive material having an intensity ratio (rare earth oxyfluoride / cerium oxide) of the strongest X-ray peak intensity among peak intensities and the strongest X-ray peak intensity among X-ray peak intensities with respect to cerium oxide. delete