JP5289687B2 - Abrasive grains for abrasive, method for producing the same, and abrasive - Google Patents

Description

  The present invention relates to abrasive grains for an abrasive, a method for producing the same, and an abrasive that can be suitably used for a method of polishing an end face of an optical connector including an optical fiber and a ferrule that covers the periphery of the optical fiber.

  An optical fiber used as a transmission means for optical communication is required to have as little optical loss as possible with the recent demand for higher capacity and higher efficiency. An optical connector is used for connection between the optical fibers. The optical connector has a ferrule. The ferrule is formed with an insertion hole through which an optical fiber is inserted. The optical fiber is fixed to the ferrule with an adhesive or the like.

  The quality of the connection end face of the optical connector is very important because it affects the optical characteristics of the optical fiber. Therefore, the optical connector end face is mirror-finished by a plurality of stages of polishing. As the final finish of polishing, precise mirror polishing is performed using an abrasive such as a polishing sheet having a polishing layer containing fine abrasive grains, a polishing tape, a polishing grindstone, and a polishing cloth.

As an abrasive used for precise mirror polishing, for example, an abrasive in which an abrasive layer containing abrasive grains and a predetermined binder is formed on a support is disclosed (Patent Documents 1 to 3). The abrasives disclosed in Patent Documents 1 and 2 are intended to solve the problem that abrasive grains and the like contained in the polishing layer remain attached to the surface to be polished. The abrasive disclosed in Patent Document 3 aims to reduce the occurrence of a step (undercut) between an optical fiber and a ferrule, which is one of the problems that occur with polishing.
JP 2004-345003 A JP 2004-322253 A Japanese Patent Laid-Open No. 2003-291068

  However, the performance required for optical fibers in recent years has been increasing, and an abrasive having higher performance than the prior art is required. Specifically, it is required at a higher level that the abrasive grains contained in the abrasive (abrasive grains for abrasive) are detached and remain on the surface to be polished, and that the level difference between the optical fiber and the ferrule is reduced. ing.

  This invention is completed in view of the said situation, and makes it the subject which should be solved to provide the abrasive grain for abrasives which can grind | polish an optical connector end surface with high precision, its manufacturing method, and an abrasive.

  The abrasive grains for abrasives of the present invention are employed in abrasives used for polishing optical connector end faces. Specifically, it is employed as an abrasive that performs polishing so that the end surfaces of the optical fiber and the ferrule are coincident and become a mirror surface. Here, the optical connector includes an optical fiber and a ferrule that covers the periphery of the optical fiber. The ferrule has a through-hole through which an optical fiber can be inserted, and the optical fiber is inserted into the through-hole so that the end surface coincides with the end surface of the ferrule.

Abrasive grains for abrasives of the present invention that solve the above problems are spherical silica fine particles,
When the spherical silica fine particles are taken as 100 parts by mass, 0.5 to 50 parts by mass of crushed silica fine particles,
It is characterized by substantially not containing particles having a particle size of 5 μm or more.

  The occurrence of undercuts and scratches can be reduced by not including particles having a particle diameter of 5 μm or more. In addition, it is possible to perform polishing with less occurrence of undercut in the state where the detachment of abrasive grains is suppressed due to the presence of spherical silica fine particles, and the grinding ability can be improved by containing a predetermined amount of crushed silica fine particles. In this specification, “particle size” means a laser diffraction / scattering particle size distribution measuring device (LA-750: manufactured by Horiba Seisakusho), a dynamic light scattering nanotrack particle size distribution analyzer (UPA-EX150: manufactured by Nikkiso Co., Ltd.) Is a value measured in combination.

  Specifically, it is confirmed that particles having a particle size of 5 μm or more are substantially not contained by measuring a fluid obtained by dropping several drops of slurry in 700 mode using a laser diffraction / scattering type particle size distribution measuring device. The particle diameter of the second fine particles having a particle diameter of 100 nm or less, which will be described later, is confirmed by performing a batch measurement using a dynamic light scattering nanotrack particle size distribution meter in a state dispersed in methyl ethyl ketone. The particle size distribution is measured by combining both measurement results. The average particle size shown below was also calculated based on the measured particle size distribution.

  From the balance between the polishing rate and the finish of the surface to be polished, it is desirable that the abrasive grains for abrasives of the present invention have a volume average particle diameter of 300 nm or less.

  Furthermore, it is desirable to have the second fine particles formed of an inorganic material and having a volume average particle diameter of 1 nm to 100 nm. The volume average particle diameter of the second fine particles is preferably 5 nm or more and 20 nm or less. The inorganic material forming the second fine particles is preferably silica. By having the second fine particles having a small volume average particle diameter, the surface specularity can be increased. Moreover, since the volume average particle diameter contains particles larger than the second fine particles, the polishing rate can be increased.

The particle size manufacturing method of the abrasive for abrasive of the present invention for solving the aforementioned problems is included the step of producing the pulverized before spherical silica fine particles by reacting metallic silicon with oxygen before the grinding spherical silica microparticles And crushing particles having a size of 5 μm or more to obtain crushed silica, and the remainder being spherical silica fine particles. In the step of producing the spherical silica fine particles before pulverization, The method for producing abrasive grains for abrasives as described above, wherein the particle having a particle size of 5 μm or more is 0.5 parts by mass or more and 50 parts by mass or less when the remainder excluding the particles of 5 μm or more is 100 parts by mass. It is .

  By crushing particles having a predetermined diameter or more that affect the mirror finish of the end face of the optical connector, the end face of the optical connector that is the surface to be polished can be properly polished.

  The abrasive of the present invention that solves the above problems combines a support base, the abrasive grains for abrasives described above or the abrasive grains for abrasives produced by the production method described above, and the abrasive grains for abrasive. And a polishing layer having a binder material and formed on the surface of the supporting substrate.

  In particular, the binder material is desirably a resin composition obtained by mixing and curing an epoxy resin and a curing agent that is an aromatic compound having two or more phenolic hydroxyl groups. By adopting the epoxy resin, the detachment of the abrasive grains can be suppressed.

  Since the abrasive grains for abrasives and the abrasives produced by the production method of the present invention have the above-described configuration, they exhibit the following effects. In other words, since spherical silica fine particles and crushed silica fine particles are blended in a well-balanced manner, it becomes possible to exhibit high polishing ability over a long period of time, enabling effective polishing and use for abrasives. The abrasive grains can be prevented from being detached from the binder material. Moreover, generation | occurrence | production of undercut can be suppressed by controlling a particle size to the above-mentioned range.

  The abrasive grains for abrasives according to the present invention, the production method thereof and the abrasives will be described in detail below.

-Abrasive material The abrasive material of this embodiment has a support base material and the abrasive layer formed in the surface. The polishing layer has abrasive grains for abrasives and a binder material that binds the abrasive grains for abrasives. This abrasive is used for polishing the end face of the optical connector. An optical connector is a member that connects a pair of optical fibers. The optical connector has a ferrule in which an insertion hole through which an optical fiber is inserted is formed. An optical connector is formed by fixing the end face of the optical fiber inserted through the ferrule so as to coincide with the end face of the ferrule. The end face of the optical connector is mirror-finished by polishing.

The abrasive grain for abrasive has spherical silica fine particles and crushed silica fine particles. The spherical silica fine particles are fine particles having a spherical appearance, and the sphericity (in this specification, a photograph is taken with an SEM, and from the area of the observed particle and the circumference, (sphericity) = {4π × ( (Area) ÷ (peripheral length) ² }, which is closer to a true sphere as it approaches 1. Specifically, an average value measured for 100 particles using an image processing apparatus is employed. ) Is 0.8 or more (preferably 0.9 or more).

  Spherical silica fine particles can be produced by reacting metallic silicon with oxygen. According to the method of producing metal silicon by reacting with oxygen, spherical silica fine particles having an average particle diameter of about 0.05 μm to 10 μm can be easily obtained.

  Crushed silica fine particles are fine particles that can be produced by crushing silica. As an external feature, it has an angular surface. In particular, it is desirable to adopt a form that can be obtained by crushing the aforementioned spherical silica fine particles. The method for crushing is not particularly limited. Examples thereof include a bead mill, a jet mill, a ball mill, and a vibration ball mill.

  The particle diameters of the spherical silica particles and the crushed silica particles are not particularly limited. The abrasive grains for abrasives may be anything that does not substantially contain particles having a particle size of 5 μm or more. In particular, those having substantially no particle having a particle diameter of 3 μm or more are desirable, and those having substantially no particle having a particle diameter of 2 μm or more are desirable. Here, “substantially free” includes not only the case where particles having a prescribed particle diameter are not completely contained, but also the case where they are inevitably included in an amount of traces. means. The volume average particle diameter of the abrasive grains for abrasive is desirably 300 μm or less, and more desirably 250 nm or less. In particular, the thickness is desirably 200 μm or less.

  The abundance ratio between the spherical silica particles and the crushed silica particles is not particularly limited. For example, when the spherical silica fine particles are taken as 100 parts by mass, it is desirable to contain 0.5 to 50 parts by mass of crushed silica fine particles, and more desirably 3 to 30 parts by mass.

  It is desirable that the abrasive grains further contain second fine particles. The second fine particles are formed of an inorganic material, and preferably have a volume average particle diameter of 1 nm to 100 nm and 5 nm to 20 nm. By adding fine particles of nanometer order, the finish of the polished surface becomes good.

  The inorganic material constituting the second fine particles is not particularly limited. For example, in addition to single element oxides such as silica, alumina, zirconia, iron oxide, chromium oxide and tin oxide, composite oxides such as silica-alumina and silica-zirconia can be employed. In particular, it is desirable to employ silica (so-called colloidal silica). The amount of the second fine particles to be mixed is preferably 1 part by mass or more and 67 parts by mass or less, and more preferably 9 parts by mass or more and 50 parts by mass or less when the entire abrasive grains for abrasives are 100 parts by mass. It is further desirable.

  It is desirable to employ a resin composition as the binder material. For example, the resin composition which hardened the epoxy resin and the urethane resin with the hardening | curing agent etc. is mentioned. The abrasive grains described above are dispersed in the binder material to form a polishing layer. Although it does not specifically limit as a ratio which mixes the abrasive grain for abrasives and a binder material, When the whole grinding | polishing layer is 100 mass parts, the quantity of abrasive grains for abrasives is 10 mass parts or more and 99 mass parts or less. It is desirable to set it to 50 parts by mass or more and 95 parts by mass or less.

  The supporting substrate is a member on which a polishing layer is formed. The surface on which the polishing layer is formed is desirably smooth. The support substrate may be in any form such as a thin film or block.

  The material which comprises a support base material should just have the elasticity and intensity | strength required, and can hold | maintain a grinding | polishing layer. For example, a film made of polyester such as polyethylene terephthalate (PET) or polybutylene terephthalate, polycarbonate, or the like is suitable. The thickness in the case of adopting a thin film as the supporting substrate is not particularly limited, and may be, for example, about 25 to 150 μm.

  In addition, a buffer layer may be formed in advance on the surface of the support base material in accordance with the purpose such as improvement in adhesion between the support base material and the polishing layer and patterning of the surface of the polishing layer. For example, an easy-adhesion layer may be formed on the surface of the support substrate to form a buffer layer. Further, the buffer layer may be formed by heat treatment, corona treatment, plasma treatment, etc. on the surface of the supporting substrate. The easy-adhesion layer can be formed by applying and drying a buffer coating solution made of, for example, an epoxy resin, an acrylic resin, or a polyester resin on the surface of the supporting substrate.

-Manufacturing method of abrasive grain for abrasive | polishing material The abrasive grain for abrasive | polishing material in this embodiment can be manufactured by adding crushing operation with respect to the spherical silica fine particle before grinding | pulverization . Particles having a particle size of 5 μm or more contained in the spherical silica fine particles before pulverization are pulverized. By crushing spherical silica fine particles before pulverization , crushing proceeds from particles having a large particle size. Particle size distribution can be controlled by controlling the crushing time because the particles are crushed from the large particle size. That is, by controlling the crushing time, it is possible to obtain abrasive grains for abrasives that do not substantially contain particles having a predetermined particle diameter or more. The obtained abrasive grains for abrasives are composed of spherical silica fine particles which are not crushed and crushed silica fine particles which are crushed and generated. Whether or not particles having a predetermined particle diameter or larger are substantially not included can be determined by determining whether the abrasive grains for abrasives can be passed through a filter having a predetermined particle diameter or smaller pore diameter in a state of being dispersed in an appropriate dispersion medium. Judge by how . When judging whether or not particles having a particle diameter of 5 μm or more are substantially not contained, a filter having a pore diameter of 5 μm is used, and it is judged by whether or not the filter can pass through. As an appropriate dispersion medium, water-based solvents such as water, alcohol, and ketone can be employed.

Silica fine particles a method of reacting metallic silicon with oxygen, a method of silica is melted by heat, a general method such as a sol-gel method can be employed. A method of obtaining spherical silica fine particles before pulverization (a step of producing spherical silica fine particles before pulverization) is a method of reacting metal silicon with oxygen. The particle size distribution of the spherical silica fine particles before pulverization is 0.5 parts by mass or more and 50 masses of particles having a particle diameter of 5 μm or more when the remainder obtained by removing particles of 5 μm or more from the spherical silica fine particles before pulverization is 100 parts by mass Or less. In order to produce the second fine particles, it is desirable to employ a sol-gel method. According to the sol-gel method, fine particles having the above-described particle size distribution can be obtained.

  There is no particular limitation on the method of bonding the manufactured abrasive grains with a binder material. For example, after dispersing abrasive abrasive grains in the prepolymer that becomes the resin constituting the binder material, the prepolymer is polymerized, or the abrasive abrasive grains are mixed directly into the resin constituting the binder material. A method of dispersing can be adopted. It is desirable that the abrasive grains for abrasives be dispersed and slurried in advance in an organic solvent, and then mixed and dispersed in a binder material. In this case, the organic solvent used as the dispersion medium is desirably a solvent that dissolves the resin (or its prepolymer) constituting the binder material or an organic solvent that can be mixed with the prepolymer itself.

(Test Example 1)
Spherical silica SO-C1 (manufactured by Admatechs) having an average particle size of 0.2 μm was dispersed in methyl ethyl ketone (MEK) to form a slurry. From this slurry, particles having a particle size of 5 μm or more were crushed by a bead mill (using 1 mm zirconia beads). Whether or not particles having a particle diameter of 5 μm or more are substantially not included was determined by whether or not the particles could pass through a 5 μm filter. The slurry before the crushing operation by the bead mill could hardly pass through the 5 μm filter, but the slurry after the crushing operation could be passed quickly.

  ZX-1059 (epoxy resin: manufactured by Tohto Kasei Co., Ltd.), which is a prepolymer of a resin constituting the binder material, in the obtained slurry (solid content: 1200 parts by mass, MEK: 1200 parts by mass), phenolic TD2131 (phenol) Resin: Dai Nippon Ink Chemical Co., Ltd.) is equivalent to ZX-1059, and triphenylphosphine (TPP) as a reaction catalyst is mixed with 3 phr (per hundred resin: ratio per 100 parts by mass of resin). Was prepared.

  This coating solution was applied onto a 75 μm thick PET film and heated at 150 ° C. to advance the curing reaction (polymerization reaction) to obtain a polishing film as an abrasive. The thickness of the obtained polishing layer was 5 μm.

(Test Example 2)
Spherical silica SO-C1 having an average particle size of 0.2 μm was dispersed in MEK to form a slurry. From this slurry, particles having a particle size of 5 μm or more were crushed by a bead mill (using 1 mm zirconia beads). Whether or not particles having a particle diameter of 5 μm or more are substantially not included was determined by whether or not the particles could pass through a 5 μm filter. The slurry before the crushing operation by the bead mill could hardly pass through the 5 μm filter, but the slurry after the crushing operation could be passed quickly.

  The obtained slurry (solid content: 600 parts by mass, MEK: 600 parts by mass) is a prepolymer of resin constituting the binder material, ZX-1059 is 100 parts by mass, Phenolite TD2131 is equivalent to ZX-1059, reaction catalyst A coating solution was prepared by mixing 2000 parts by weight of TPP as 3 phr and silica sol MEK-ST (volume average particle diameter 20 nm, manufactured by Nissan Chemical Co., Ltd .: solid content 30%) as the second fine particles.

  This coating solution was applied onto a 75 μm thick PET film and heated at 150 ° C. to advance the curing reaction to obtain a polishing film. The thickness of the obtained polishing layer was 5 μm.

(Test Example 3)
Spherical silica SO-C1 having an average particle size of 0.2 μm was dispersed in MEK to form a slurry.

  The obtained slurry (solid content: 1200 parts by mass, MEK: 1200 parts by mass) is a prepolymer of resin constituting the binder material, ZX-1059 is 100 parts by mass, Phenolite TD2131 is equivalent to ZX-1059, reaction catalyst The coating solution was prepared by mixing 3 phr of TPP.

  This coating solution was applied onto a 75 μm thick PET film and heated at 150 ° C. to advance the curing reaction to obtain a polishing film. The thickness of the obtained polishing layer was 5 μm.

(Test Example 4)
Silica sol MEK-ST5000 parts by mass, ZX-1059 was 100 parts by mass, Phenolite TD2131 was equivalent to ZX-1059, and TPP as a reaction catalyst was mixed with 3 phr to prepare a coating solution.

  This coating solution was applied onto a 75 μm thick PET film and heated at 150 ° C. to advance the curing reaction to obtain a polishing film. The thickness of the obtained polishing layer was 5 μm.

(Evaluation method)
Polishing machine: Each test polishing film was attached to SPF-120A (manufactured by Seiko Giken Co., Ltd.), and distilled water was dropped onto the polishing film to polish a Φ2.5 mm optical connector. Polishing conditions were performed at a predetermined pressure for 30 seconds.

  The end face of the optical connector was evaluated after cleaning. In addition, before the said grinding | polishing, it grind | polished for 30 second by the predetermined pressure with the diamond grinding | polishing sheet | seat of 1 micrometer as a pretreatment.

-Optical loss rate The return loss (optical loss rate) of the optical fiber was obtained at a wavelength of 1310 nm using an AR-301R (NTT-AT) inspection machine. This optical loss rate is a measurement of the amount of transmitted light loss caused by reflection at the end face of the optical connector. The smaller the value expressed in dB (larger in the negative direction), the lower the transmission loss and the lower the transmission loss. And shows a good transmission state.

-Level difference The level | step difference of the end surface of a fiber and a ferrule was calculated | required with the measuring machine of AC3000-NT (NTT-AT company). The height from the center position of the virtual curve of the ferrule end face to the center position of the fiber end face is a step, + value is the protruding direction, and-value is the drawing direction. ± 0 is optimal and ± 50 nm is an acceptable value.

-Scratch Twelve end faces of 12 optical connectors polished with a microscope having a magnification of 400 times were inspected. Judgment was made based on the number of fibers in which scratches occurred. One or less was marked ◎, 2-3 were marked as ◯, 4-5 were marked as Δ, and six or more were marked as x.

(result)
The results are shown in Table 1.

  As is apparent from Table 1, the optical connector polished with the abrasive of Test Example 1 containing abrasive particles for abrasives in which large particles (particle size of 5 μm or more) were crushed was such that Test Example 3 in which large particles were not crushed The optical loss rate was lower than that of the end face of the optical connector polished with this abrasive, and there were few steps generated. Furthermore, there was little occurrence of scratches.

  The end face of the optical connector polished with the abrasive of Test Example 2 containing silica sol as the second fine particle after crushing particles having a particle diameter of 5 μm or more is the same as that of the optical connector polished with the abrasive of Test Example 1 The optical loss rate, level difference and scratch were more preferable than the end face.

  That is, by adopting abrasive grains for abrasives, in which large particles were crushed, the properties of the surface to be polished could be made favorable. Further, the performance could be further improved by containing the second fine particles.

Claims (8)

Spherical silica fine particles,
When the spherical silica fine particles are taken as 100 parts by mass, 0.5 to 50 parts by mass of crushed silica fine particles,
An abrasive grain for an abrasive used for polishing an optical connector end face, which does not substantially contain particles having a particle diameter of 5 μm or more. The abrasive grain according to claim 1, wherein the volume average particle diameter is 300 nm or less. The abrasive grain for abrasives according to claim 1 or 2 , comprising a second fine particle formed of an inorganic material and having a volume average particle diameter of 1 nm or more and 100 nm or less. The abrasive grain for abrasives according to claim 3 , wherein the volume average particle diameter of the second fine particles is 5 nm or more and 20 nm or less. The abrasive grain for abrasives according to claim 3 or 4 , wherein the inorganic material forming the second fine particles is silica. A step of reacting metallic silicon with oxygen to produce spherical silica fine particles before grinding ;
A step of crushing particles having a particle size of 5 μm or more contained in the spherical silica fine particles before pulverization into crushed silica, and the remainder being spherical silica fine particles ,
In the step of producing the spherical silica fine particles before pulverization, when the remaining amount obtained by removing the particles of 5 μm or more from the spherical silica fine particles before pulverization is 100 parts by mass, the particles having a particle diameter of 5 μm or more are 0.5 mass. Part to 50 parts by weight,
The manufacturing method of the abrasive grain for abrasives according to any one of claims 1 to 5 . A support substrate;
The abrasive grain for abrasives according to any one of claims 1 to 5 or the abrasive grain for abrasives produced by the production method according to claim 6 and a binder material for binding the abrasive grains for abrasives. A polishing layer formed on the surface of the supporting substrate;
A polishing material used for polishing an optical connector end face. The abrasive according to claim 7 , wherein the binder material is a resin composition obtained by mixing and curing an epoxy resin and a curing agent that is an aromatic compound having two or more phenolic hydroxyl groups.