JP4882292B2 - Manufacturing method of polishing cloth - Google Patents

Description

  The present invention relates to a polishing cloth for high-precision polishing used for finishing a recording medium and an integrated circuit board, and a manufacturing method thereof. More particularly, the present invention relates to a polishing cloth for texture processing of a hard disk, a polishing cloth for secondary polishing of a hard disk, a polishing cloth for finishing an integrated circuit board or a precision instrument, and a manufacturing method thereof.

  Magnetic recording media such as magnetic disks are required to have higher capacities and higher recording densities due to remarkable technological innovations in recent years. For this reason, higher density of substrate surface processing is required. For example, as a substrate of a magnetic recording medium used in a hard disk device, for example, an aluminum substrate (a mirror-polished Al—Mg alloy base material obtained by electroless plating a Ni—P alloy film) or a glass substrate (amorphous) Glass or crystallized glass with a mirror finish) is generally used, but when performing texture processing to form fine streaks on these, a polishing cloth that can be polished with high accuracy and stability is used. Necessary. From such a background, various polishing cloths have been studied so far. For example, a fabric made using a fine fiber (for example, Patent Document 1) and a nonwoven fabric (for example, Patent Document 2) are disclosed. ing. In particular, an abrasive cloth including a polymer elastic body and having a nap-like surface in a non-woven fabric has a role of appropriately pressing abrasive particles against the surface of the substrate, and thus is a preferred form.

Here, if the unevenness of the polishing cloth surface is large, scratches (hereinafter referred to as scratches) occur on the substrate surface when polishing, resulting in a problem that productivity is lowered. For example, when a resin such as a polymer elastic body is exposed on the surface of the polishing cloth, there is a problem that causes a scratch. Further, the same applies to the case where ultrafine fibers are converged and apparently present as thick fibers. In order to solve this, a polishing cloth having a polishing surface made of an entangled nonwoven fabric or a melt blown nonwoven fabric is disclosed (for example, Patent Document 3). According to this method, since the fibers are not fixed with the resin, the falling off of the resin and the exposure of the resin to the surface are reduced, and the scratch caused by this can be reduced. However, according to the knowledge of the present inventors, it was found that the polishing cloth obtained by the disclosed method did not sufficiently satisfy the current requirements because of the occurrence of scratches due to fiber dropping due to use. .
JP-A-11-90810 JP 2003-236739 A Japanese Patent Laid-Open No. 9-262775

  This invention solves the said subject and provides the polishing cloth which can suppress generation | occurrence | production of a scratch, and its manufacturing method.

  In order to solve the above problems, the present invention has the following configuration.

The manufacturing method of the abrasive cloth which consists essentially of the fiber material of the present invention is a method for producing a short fiber nonwoven fabric by a needle punch method using 1 to 10 dtex short fibers capable of generating 0.0001 to 0.2 dtex ultrafine fibers. After being manufactured and then subjected to ultrathinning, a high-speed fluid flow treatment is performed at a pressure of at least 15 MPa, and then raising treatment is performed.

  According to the present invention, a resin such as a polymer elastic body is not exposed on the surface, and fibers are not easily dropped off. Therefore, it is possible to provide an abrasive cloth that hardly causes scratches on a substrate. In addition, since the ultrafine fibers do not substantially form a fiber bundle, uniform processing can be performed.

  The polishing cloth of the present invention is a non-woven fabric structure substantially made of a fiber material having at least one surface raised. At least one surface means a surface mainly used for polishing the substrate (hereinafter referred to as the front surface), and the other surface (hereinafter referred to as the back surface) is not particularly limited. In order to improve the properties, a normal woven or knitted fabric, a normal fineness nonwoven fabric, a film, or the like may be provided. Among these, a woven fabric is particularly preferable because it is excellent in form stability, hardly peels off from the nonwoven fabric layer, and is relatively easy to produce. The woven structure is not particularly limited, and various types such as a plain weave, a twill weave, and a changed structure can be selected, but a plain weave is preferable in terms of cost and form stability. Moreover, what is substantially comprised from a fiber raw material shows that resin, such as a polymeric elastic body, is not exposed between the fibers of a nonwoven fabric when the surface is observed by SEM observation etc. Therefore, the polymer elastic body may be contained in the nonwoven fabric as long as the effect of the present invention is not impaired, but it is preferably not substantially contained because it may be exposed. As a result, it is possible to suppress the occurrence of scratches caused by the resin falling off or being exposed. In addition, when the substrate is hard, the grinding speed can be increased. However, if the fibers fall off due to polishing, scratches may occur due to this, and therefore it is preferable that the ultrafine fibers on the surface are intertwined. In particular, in the surface layer portion in the range of 0.2 mm from the surface, the ultrafine fibers do not form fiber bundles, and the ultrafine fibers are intertwined with each other, which suppresses fiber dropping and improves surface smoothness. Therefore, it is preferable.

  In addition, the non-woven fabric having napped fibers is excellent in holding of abrasive grains used for polishing and has a role of suppressing aggregation, suppressing generation of scratches and enabling uniform polishing.

  The single fiber fineness of the polishing cloth of the present invention is mainly 0.0001 to 0.2 dtex. The single fiber fineness is preferably 0.001 to 0.1 dtex, more preferably 0.001 to 0.05 dtex. If it is less than 0.0001 dtex, the surface roughness of the polishing cloth tends to increase due to fiber cutting or fiber aggregation, and the smoothness of the substrate tends to decrease. This is not preferable because of the occurrence of scratches on the substrate. On the other hand, if it exceeds 0.2 dtex, the surface roughness of the surface of the polishing cloth increases and the denseness of the nappings decreases, which is not preferable for the same reason.

  The nonwoven fabric employed in the polishing cloth of the present invention is composed of short fibers in that the density of fiber napping is excellent, and the fiber length is 10 cm or less, preferably 7 cm or less. Those having a fiber length exceeding 10 cm may be included as long as the effects of the present invention are not impaired. The lower limit is not particularly limited, and can be appropriately set depending on the method for producing the nonwoven fabric. However, if it is less than 0.1 cm, the fibers are more likely to fall off, and it is not preferable because scratches are easily generated on the substrate.

Next, the abrasive cloth of the present invention has an apparent fiber density of 0.19 to 0.5 g / cm ³ . Fibers apparent density is preferably 0.2-0.5 g / cm ^3, further preferably 0.25~0.4g / cm ^3. If it is less than 0.19 g / cm ³ , the surface becomes rough, the form retentivity decreases, elongation occurs during processing, and irregularities are formed on the surface of the polishing cloth, making uniform polishing difficult. Become. On the other hand, if it exceeds 0.5 g / cm ³ , the retainability of the abrasive grains decreases and scratches are likely to occur, which is not preferable.

  The fiber apparent density was determined by measuring the basis weight according to JIS L 1096 8.4.2 (1999), then measuring the thickness, and taking the average value of the fiber apparent density obtained therefrom as the fiber apparent density. For thickness measurement, a dial thickness gauge (manufactured by Ozaki Seisakusho Co., Ltd., trade name “Peacock H”) was used to measure 10 samples, and the average value was used. In addition, the fiber apparent density in the present invention refers to the apparent density of the fiber material. For example, in the case of a nonwoven fabric structure impregnated with a resin other than the fiber material, the apparent density of the fiber material excluding the resin is shown. .

  Further, the polishing cloth of the present invention has a tensile strength in at least one direction, preferably in the vertical direction, of 70 N / cm or more, and preferably 80 N / cm or more. If the tensile strength is less than 70 N / cm, there is a tendency for problems such as variation in polishing characteristics due to dimensional changes and the like, which is not preferable. In addition, although an upper limit is not specifically limited, Usually, it will be 200 N / cm or less. The tensile strength here refers to a sample having a width of 5 cm and a length of 20 cm taken according to JIS L 1096 8.12.1 (1999), and a tensile speed of 10 cm / Determined by stretching in minutes. From the obtained value, the load per 1 cm width was defined as tensile strength (unit: N / cm). In order to obtain these strengths, the strength of the fibers used is preferably 2 cN / decitex or higher. Moreover, it can adjust also by laminating | stacking a textile fabric, a film, etc.

  Further, in order to suppress a decrease in processing stability due to elongation during polishing, it is important that the 10% modulus in the vertical direction is 3 N / cm or more, preferably 5 N / cm, and preferably 7 N / cm. It is more preferable. The upper limit is not particularly limited. However, if it exceeds 50 N / cm, the polishing pressure tends to vary and the uniformity is lowered, which is not preferable. The 10% modulus was measured in the same manner as the tensile strength measurement method, and the strength at 10% elongation was taken as the value.

  The polishing cloth of the present invention has a surface roughness of 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less. The lower limit is not particularly limited and is preferably as small as possible, but is usually 0.1 μm or more. If the surface roughness exceeds 10 μm, scratches tend to occur, and the substrate surface roughness (Ra) after polishing increases, which is not preferable. In addition, the surface roughness as used in the field of this invention is the value measured by KES method using surface tester KES-FB4 (made by Kato Tech Co., Ltd.). In the case of napping, the value is different depending on the direction of napping and the direction in which the napping is detected, and the values are different, but the lower value is defined as the surface roughness.

  The polymer constituting the fiber is not particularly limited as long as it is a polymer having fiber forming ability, and various polymers can be selected according to the purpose and application. For example, in the texture processing for forming fine streaks on the substrate surface of the recording disk, the fiber type used for the polishing cloth can be changed depending on the material of the substrate. Further, from the viewpoints of wear resistance, abrasive retention, dispersibility, and surface smoothness, the polymer constituting the fiber is preferably a polyamide. Examples of the polyamide include polymers having an amide bond such as nylon 6, nylon 66, nylon 610, nylon 12, and the like. This can be preferably used when the above-mentioned texture processing is used, particularly when the aluminum alloy substrate is plated with a Ni-P alloy or the like.

  On the other hand, when the substrate material is hard, the polymer constituting the fiber is preferably polyester. In particular, a polishing cloth for texture processing of a recording disk made of a glass substrate is preferable because a high grinding force is required to directly grind the glass. The polyester is not particularly limited as long as it is a polymer synthesized from a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof and can be used as a fiber. Specifically, for example, polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, polyethylene-1,2-bis (2- Chlorophenoxy) ethane-4,4′-dicarboxylate and the like. In the present invention, polyethylene terephthalate, which is most commonly used, or a polyester copolymer mainly containing ethylene terephthalate units is preferably used.

  Further, in one embodiment of the polishing cloth of the present invention, the water drop absorption time of the polishing cloth is preferably 1 to 60 seconds, more preferably 2 to 30 seconds, and further preferably 2 to 10 seconds. When it exceeds 60 seconds, when the abrasive grains are continuously supplied onto the polishing surface, the polishing surface is slow to become wet, the abrasive grains cannot be sufficiently dispersed, and scratches are likely to increase, resulting in a decrease in polishing accuracy. To do. Further, if the water absorption time is less than 1 second, it is not preferable because it causes aggregation of abrasive grains and generation of scratches. The water droplet absorption time referred to in the present invention is a FACE / CA-A type contact angle assumption device manufactured by Kyowa Interface Science Co., Ltd., and distilled water is put into a syringe attached to the device and an injection needle (outer diameter 0.60 mm, One drop of water from an inner diameter of 0.45 mm is dropped on the polishing cloth, and the water drop is observed from the eyepiece of the apparatus, and is calculated by the following formula.

tq (water droplet absorption time) = t2-t1 (seconds)
Here, the time when the water droplet fell on the polishing cloth is defined as t1, and the time when the water droplet is sucked into the polishing cloth as time passes and the water droplet disappears on the surface is defined as t2.

  The state of t1 and t2 can be measured visually in the normal case (approximately tq is 10 seconds or more), but when it is very fast or difficult to observe, water droplets start dropping from the injection needle with the aforementioned device. The entire state of the water droplet is video-recorded through the eyepiece of the apparatus until the water droplet is sufficiently absorbed into the polishing cloth. The video image is reproduced, and the water droplet absorption time can be measured from the states of t1 and t2 and the recording time.

  In addition, the water absorption time tq is obtained by performing 20 measurements on a sample arbitrarily taken from the product, and taking the average value of the 5 largest data among the 20 measured values (tq). Let the average value be the value of water absorption time.

  Furthermore, the contact angle between the polishing cloth surface and water droplets is one of the factors when the abrasive grains are uniformly dispersed on the polishing cloth surface, and the contact angle of the polishing cloth in the present invention is 10 to 60 °. Preferably, it is 10-30 degrees. When it is 60 ° or less, not only the dispersion but also the retention of the abrasive grains on the surface of the polishing cloth and the familiarity are improved, and the polishing accuracy is improved. The lower limit is not particularly limited, but is usually 10 ° or more.

  Here, the contact angle can be measured by a droplet method under the conditions of a temperature of 20 ° C. and a humidity of 60%, using a device similar to a water droplet absorption time measuring device. In addition, the contact angle was measured using 20 samples as in the measurement of water absorption time, and the average value of the 5 largest data among the 20 measured values was taken. The average value was taken as the contact angle value.

  Means for improving the water droplet absorption time and contact angle to the scope of the present invention are not particularly limited, and fibers that are excellent in water absorption are used and are comprehensively adjusted by the density and fiber fineness of the nonwoven fabric. Furthermore, even if the base material is the same, it is possible to perform a hydrophilic treatment with a hydrophilic component solution, and it is an effective and preferable method.

  Here, the organic hydrophilic component is not particularly limited, but surfactants, polyamide-based, polyester-based, acrylic-based, silicone-based, and PVA-based polymers are preferably used. And after processing by immersion treatment, spraying treatment, coating treatment, etc. using the solution or emulsion aqueous solution, it dries at 80-190 ° C, and adheres. The surfactant includes ionic and nonionic surfactants, but nonionic surfactants are preferred from the viewpoint of avoiding metal components. In addition, if the water absorption of the entire polishing cloth is increased too much, the abrasive slurry penetrates into the base cloth and the efficiency is lowered. Therefore, the entire surface is processed with a hydrophilic component treating agent after slightly water-repellent treatment, and water absorption A method for suppressing the property is also preferable.

  On the other hand, in another embodiment of the polishing cloth of the present invention, the water droplet absorption time of the polishing cloth is preferably more than 60 seconds, more preferably more than 80 seconds. By exceeding 60 seconds, it becomes difficult for the slurry used for polishing to fall out to the inner layer portion of the polishing pad base material, and the grinding efficiency and line density are improved. The water droplet absorption time is preferably less than 1 hour, and more preferably less than 30 minutes. When it becomes 1 hour or more, the retention property of the pellet slurry is deteriorated, and good grinding becomes difficult. The water drop absorption time at this time can be measured by the method described above.

  Furthermore, it is preferable that the contact angle between the polishing cloth surface and the water droplets exceeds 60 ° and is less than 130 ° because the effect of improving the polishing efficiency and the line density is obtained. If it is 60 ° or less, this effect is hardly exhibited. Moreover, although an upper limit is not specifically limited from a viewpoint of an effect, Usually, it will be less than 130 degrees. The contact angle at this time can be measured by the method described above.

  The means for increasing the water droplet absorption time or increasing the contact angle is not particularly limited, and is a fiber that is excellent in water repellency and is comprehensively adjusted by the density and fiber fineness of the nonwoven fabric. However, even if the base materials are the same, it is possible to perform the hydrophobization processing with a hydrophobic component solution, and it is an effective and preferable method.

  Here, the organic hydrophobic component is not particularly limited, but fluorine resin, silicon resin, wax system, and paraffin system are preferably used. The solution or the emulsion aqueous solution is used for immersion treatment, spray treatment, coating treatment, etc., and then dried and fixed at 80 to 190 ° C.

  The use of the polishing cloth of the present invention is not particularly limited, and as a high-precision polishing used for finishing a recording medium or an integrated circuit board, for example, a polishing cloth for texturing of a hard disk, a polishing cloth for secondary polishing of a hard disk. It can be used as a polishing cloth for finishing integrated circuit boards and precision equipment. Among these, it is preferable to use it as a polishing cloth for texturing of a hard disk as an application that can further exert the effects of the present invention.

  Next, an example of the preferable manufacturing method of the abrasive cloth of this invention is demonstrated.

  In the polishing cloth of the present invention, the so-called ultrafine fiber production method in which the single fiber fineness is within the scope of the present invention is not particularly limited. For example, a method of directly spinning ultrafine fibers, usually fineness fibers and generating ultrafine fibers. Can be produced by a method of spinning fibers that can be used (hereinafter referred to as ultrafine fiber-generating fibers) and then generating ultrafine fibers. Examples of the method using the ultrafine fiber-generating fiber include a method of removing sea components after spinning the sea-island type fiber, a method of spinning the split-type fiber and then splitting it to make it ultrafine. Among these, in the present invention, it is preferable to manufacture with an island-in-sea fiber or a split-type fiber, and more preferable to manufacture with an island-in-sea fiber, from the viewpoint that ultrafine fibers can be obtained easily and stably.

  The sea-island fiber referred to in the present invention refers to a fiber in which two or more components are combined and mixed at any stage to obtain a sea-island state, and the method for obtaining this fiber is not particularly limited. For example, (1) A method of blending and spinning two or more polymers in a chip state, (2) A method of kneading a polymer of two or more components in advance to form a chip and then spinning, (3) A polymer of two or more components in a molten state Examples thereof include a method of mixing with a stationary kneader or the like in a pack of a spinning machine, and (4) a method of manufacturing using a die such as JP-B No. 44-18369 and JP-A No. 54-116417. In the present invention, any of the methods can be used for satisfactory production, but the method (4) is preferably employed in that the polymer can be easily selected and the dispersibility of the ultrafine fibers is excellent.

  In the method (4), the cross-sectional shape of the island fiber obtained by removing the sea-island fiber and the sea component is not particularly limited, and examples thereof include a circle, a polygon, Y, H, X, W, C, and π type. Can be mentioned. Further, the number of polymer species to be used is not particularly limited, but it is preferably 2 to 3 components in consideration of spinning stability, and particularly preferably composed of 2 components of sea 1 component and island 1 component. . In addition, the component ratio at this time is preferably 0.1 to 0.99 by weight ratio of island fibers to sea-island fibers, more preferably 0.2 to 0.97, and 0.4 to 0.8. Is more preferable. If it is less than 0.1, the removal rate of sea components increases, which is not preferable in terms of cost. On the other hand, if it exceeds 0.99, the island components are likely to merge with each other, which is not preferable in terms of spinning stability.

  Next, the ultrafine fiber-generating fibers thus obtained are entangled to obtain a nonwoven fabric. As a method for forming the nonwoven fabric, a dry method in which a web is obtained using a card, a cross wrapper, a random weber, or a wet method by a papermaking method can be adopted. In the present invention, a needle punch method and a high-speed fluid flow treatment are used. A dry method that can easily combine these two entanglement methods is preferred. In the entanglement treatment, other woven fabrics, knitted fabrics, and nonwoven fabrics can be laminated and integrated in order to impart appropriate elongation or non-elongation, or to improve physical properties such as strength of the obtained nonwoven fabric.

  A preferable method for obtaining the abrasive cloth of the present invention is to produce a short fiber nonwoven fabric by a needle punch method using 1 to 10 dtex fibers capable of generating ultrafine fibers, and then a high-speed fluid flow treatment at a pressure of at least 10 MPa or more. For example, a water jet punch process using a water flow is performed. A high degree of entanglement can be achieved by combining this needle punch method and high-speed fluid flow treatment.

The short fiber nonwoven fabric preferably has a fiber apparent density of 0.12 to 0.3 g / cm ³ , more preferably 0.15 to 0.25 g / cm ³ by needle punching. When it is less than 0.12 g / cm ³ , the entanglement is insufficient, and the desired physical properties are difficult to obtain. The upper limit is not particularly defined, but if it exceeds 0.3 g / cm ³ , problems such as breakage of the needle needle and remaining of the needle hole are not preferable.

  Moreover, when performing needle punching, it is preferable that the single fiber fineness of an ultrafine fiber generation type | mold fiber is 1-10 dtex, 2-8 dtex is more preferable, and 2-6 dtex is further more preferable. When the single fiber fineness is less than 1 dtex or exceeds 10 dtex, the entanglement by the needle punch becomes insufficient, and it becomes difficult to obtain an ultra-fine short fiber nonwoven fabric with good physical properties.

In the needle punch according to the present invention, it is preferable that the fibers are sufficiently entangled rather than merely serving as temporary fixing for obtaining process passability as described above. Therefore, the driving density is preferably 100 / cm ² or more, more preferably 500 / cm ² or more, and still more preferably 1000 / cm ² or more.

  The composite short fiber nonwoven fabric thus obtained is preferably shrunk by dry heat and / or wet heat, and further densified.

  Thus, the tensile strength and 10% modulus can be improved by sufficient needle punching treatment, shrinkage treatment, and the like.

  Subsequently, it is preferable that the ultrafine fibers are entangled by performing a high-speed fluid flow treatment after performing the ultrafine treatment, simultaneously with the ultrafine treatment, or simultaneously with the ultrafine treatment and thereafter. Although it is possible to combine the high-speed fluid flow treatment with the ultrafine treatment, it is preferable to perform the high-speed fluid flow treatment even after at least the ultrafine treatment is mostly completed in order to further promote the entanglement between the ultrafine fibers, Furthermore, it is preferable to perform the high-speed fluid flow process after performing the ultrafine process.

  The ultrafine treatment method is not particularly limited, and examples thereof include a mechanical method and a chemical method. The mechanical method is a method of miniaturization by applying a physical stimulus, for example, a method of applying pressure between rollers in addition to the method of giving an impact such as the needle punch method or the water jet punch method described above, Examples include a method of performing ultrasonic treatment. The chemical method includes, for example, a method in which at least one component constituting the sea-island fiber is subjected to a change such as swelling, decomposition, dissolution, etc. by a drug. In particular, a method of producing a short fiber nonwoven fabric with ultrafine fiber-generating fibers using an alkali-degradable sea component, and then treating it with a neutral to alkaline aqueous solution to make it ultrafine is preferable in working environment without using a solvent. Therefore, this is one of the preferred embodiments of the present invention. The neutral to alkaline aqueous solution here is an aqueous solution having a pH of 6 to 14, and the chemicals used are not particularly limited. For example, an aqueous solution containing organic or inorganic salts may be used as long as it exhibits a pH in the above range, and alkali metal salts such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate, calcium hydroxide, water Examples include alkaline earth metal salts such as magnesium oxide. Further, if necessary, amines such as triethanolamine, diethanolamine, monoethanolamine, a weight loss accelerator, a carrier, and the like can be used in combination. Of these, sodium hydroxide is preferable in terms of price and ease of handling. Furthermore, it is preferable that the sheet is subjected to the neutral to alkaline aqueous solution treatment described above, and then neutralized and washed as necessary to remove the remaining chemicals and decomposition products, and then dried.

  As a method of simultaneously performing these ultrafine treatment and high-speed fluid flow treatment, for example, a method of using a composite fiber composed of a water-soluble sea component and performing removal and entanglement by a water jet punch, two or more components having different alkali decomposition rates And a method of performing a final removal and an entanglement treatment by a water jet punch after decomposing an easily soluble component through an alkali treatment liquid.

  As the high-speed fluid flow treatment, it is preferable to perform a water jet punch treatment using a water flow in terms of the working environment. At this time, it is preferable to perform the water in a columnar flow state. In order to obtain a columnar flow, it is usually obtained by ejecting from a nozzle having a diameter of 0.06 to 1.0 mm at a pressure of 1 to 60 MPa. In order to obtain efficient entanglement and good surface quality, this treatment preferably has a nozzle diameter of 0.06 to 0.15 mm and an interval of 5 mm or less, and a diameter of 0.06 to 0.12 mm. The interval is more preferably 1 mm or less. These nozzle specifications do not need to be all the same when processing multiple times. For example, a nozzle having a large hole diameter and a small hole diameter can be used in combination, but the nozzle having the above configuration is used at least once. It is preferable. In particular, when the diameter exceeds 0.15 mm, the entanglement property between the ultrafine fibers decreases, the surface becomes easy to peach, and the surface smoothness also decreases. Accordingly, a smaller nozzle hole diameter is preferable. However, if the nozzle hole diameter is less than 0.06 mm, nozzle clogging is likely to occur. Further, for the purpose of achieving uniform entanglement in the thickness direction and / or improving the smoothness of the nonwoven fabric surface, the treatment is preferably repeated a number of times. Further, the water flow pressure is appropriately selected according to the basis weight of the nonwoven fabric to be treated, and the higher the basis weight, the higher the pressure. Furthermore, in order to highly entangle the ultrafine fibers, it is preferable to treat at least once with a pressure of 10 MPa or more, and more preferably 15 MPa or more. Further, the upper limit is not particularly limited, but the cost increases as the pressure increases, and if the basis weight is low, the nonwoven fabric may be non-uniform, and fluff may be generated by cutting the fiber, and therefore preferably 40 MPa. Or less, more preferably 30 MPa or less. By doing so, for example, in the case of ultrafine fibers obtained from sea-island type fibers, it is common that the ultrafine fiber bundles in which the fibers are concentrated are mainly entangled, but in the present invention, the entanglement by the ultrafine fiber bundles It is possible to obtain an ultra-fine short fiber nonwoven fabric in which ultra-fine fibers are highly entangled to such an extent that almost no fiber is observed, and it is also possible to improve surface properties such as wear resistance. Note that a water immersion process may be performed before the water jet punch process. Furthermore, in order to improve the surface quality, a method of relatively moving the nozzle head and the nonwoven fabric, a method of inserting a wire mesh between the nonwoven fabric and the nozzle after entanglement, and a watering treatment can be performed. Further, before performing the high-speed fluid flow treatment, it is preferable to perform the split treatment on two or more sheets perpendicular to the thickness direction. In this way, the ultrafine fibers are preferably entangled until the 10% modulus in the vertical direction is 5 N / cm or more, more preferably 6 N / cm or more.

  The present invention pays attention to the difference between a fiber that is easily entangled by needle punching and a fiber that is easily entangled by high-speed fluid flow treatment. It has been found that an ultra-fine short fiber nonwoven fabric can be obtained. In other words, the entanglement by the needle punch is excellent when the fiber of 1 to 10 dtex is thick, and the entanglement by the high-speed fluid flow treatment tends to be excellent in the ultrafine region of 0.0001 to 0.2 dtex. is there. In order to combine these fiber fineness and the entanglement method, the fine fiber generation type fiber having a fineness of 1 to 10 dtex is sufficiently entangled by needle punching, and then an ultrafine fiber of 0.0001 to 0.2 dtex is obtained. It is preferable to perform the high-speed fluid flow treatment after the ultrafine treatment, simultaneously with the ultrafine treatment, or simultaneously with and after the ultrafine treatment.

  In producing the polishing cloth of the present invention, a polymer elastic body such as urethane may be imparted within a range not impairing the effects of the present invention. In this case, after manufacturing the ultra-fine short fiber nonwoven fabric, the polymer elastic body is impregnated. As such a polymer elastic body, various materials having desired texture, physical properties and quality can be appropriately selected and used, and examples thereof include polyurethane, acrylic, styrene-butadiene and the like. Among these, it is preferable to use polyurethane from the viewpoint of flexibility. The method for producing polyurethane is not particularly limited, and can be produced by appropriately reacting a conventionally known method, that is, polymer polyol, diisocyanate, and chain extender. Moreover, although it may be a solvent system or an aqueous dispersion system, the aqueous dispersion system is preferred from the viewpoint of the working environment.

  When impregnating the polymer elastic body, sufficient care must be taken so that the polymer elastic body is not substantially exposed on the surface. From that viewpoint, the amount of the elastic polymer is preferably 10% or less, more preferably 5% or less, and still more preferably 2% or less of the total weight. In addition, when using a solvent-based polymer elastic body, a wet coagulation method is adopted. When using a water-dispersed polymer elastic body, a heat-sensitive coagulation material is used. It is preferable to suppress.

  However, it is preferable that the polishing cloth of the present invention has a clearer feature and is superior to the conventional one, and is substantially free of a polymer elastic body and mainly made of a fiber material. Furthermore, it is preferable that the fiber material is substantially composed of non-elastic polymer fibers. Further, the absence of the polymer elastic body also has the effect of increasing the rigidity of the polishing cloth and obtaining a higher grinding force.

  Further, it is preferable to perform the stagnation treatment because dispersibility of napping is improved, and dispersibility and retention of abrasive grains during polishing are improved. The stagnation treatment can be generally performed by an apparatus called a texture processing machine or a dyeing machine. Specifically, a liquid dyeing machine, a Wins dyeing machine, a jigger dyeing machine, a tumbler, a relaxer, or the like can be used. In the present invention, the stagnation treatment is preferably performed after the high-speed fluid flow treatment. When the stagnation treatment is performed before the high-speed fluid flow treatment is performed, the effect is greatly reduced by the high-speed fluid flow treatment, and the dimensional change during the stagnation processing is not preferable.

  Furthermore, after performing high-speed fluid flow treatment, when the thickness is compressed 0.1 to 0.8 times at a temperature of 100 to 250 ° C. by a calender, the apparent fiber density can be increased and the surface smoothness is excellent. It is preferable in that the surface roughness can be easily adjusted within the range of the present invention. If the compression is less than 0.1 times, the texture is too hard, which is not preferable. Moreover, although it may exceed 0.8 times, the compression effect is reduced. Furthermore, even if it processes at less than 100 degreeC, the effect of compression will decrease and it is not preferable. Further, treatment at a temperature exceeding 250 ° C. is not preferable because scratches are likely to occur due to fiber fusion or the like. Note that compression before the high-speed fluid flow treatment is not preferable because entanglement due to the high-speed fluid flow treatment is difficult to proceed.

  Furthermore, it is preferable to use a sandpaper, a brush or the like in order to obtain a napped surface. The order of the napping treatment, the stagnation treatment and the compression treatment described above is not particularly limited as long as it is after the high-speed fluid flow treatment, but the stagnation treatment is performed in order to increase the smoothness in the final product. After that, it is preferable to perform compression treatment and then perform napping treatment.

  In the polishing cloth of the present invention, as a preferable method for adjusting the water droplet absorption time and the contact angle, treatment with a hydrophilic compound or a hydrophobic compound is raised. This treatment may be performed at any timing among the above-described production methods, but is preferably an entanglement treatment such as a needle punch or a water jet punch in terms of easy adjustment of the water droplet absorption time and the contact angle. More preferably, after napping treatment is performed. In this case, it is necessary to appropriately adjust the treatment chemical and the applied amount according to the purpose depending on the density and fineness of the substrate, the fiber type to be used, and the like.

  For example, in the polishing cloth of the present invention, when the treatment is performed for the purpose of reducing the water droplet absorption time and / or for the purpose of reducing the contact angle, the surfactant, acrylic, silicone, PVA polymer, etc. One or more components are selected and the solution or emulsion solution is dipped or sprayed onto the nonwoven fabric surface and then dried and fixed. The surfactant includes ionic and nonionic surfactants, but nonionic surfactants are preferred from the viewpoint of avoiding metal components.

  On the other hand, in the polishing cloth of the present invention, when the treatment is performed for the purpose of increasing the water droplet absorption time and / or for the purpose of increasing the contact angle, for example, an oligomer or polymer containing silicon, fluorine, etc., an olefin polymer, paraffin Etc. can be processed by dipping, spraying, etc., as described above.

  Moreover, in order to balance water absorption and water repellency, a hydrophilic component treatment can also be performed after the water repellent treatment.

  In the case of a polishing cloth including a woven or knitted fabric or a film, the laminating method is not particularly limited, and it is a means for overlapping and entangled during the above-described needle punch or high-speed fluid treatment, or a means by adhesion. It can be carried out. Among these, the method using high-speed fluid flow treatment is preferable because peeling can be prevented, cost can be suppressed, and various woven and knitted fabrics can be easily laminated. By these means, it is possible to improve the tensile strength and 10% modulus.

  Hereinafter, the present invention will be described in more detail with reference to examples. In the polishing evaluation, Ni-P plating on an aluminum plate and polishing were performed on a substrate A (substrate) having an average surface roughness of 2.8 angstroms or a substrate B (substrate) using amorphous glass as follows. Each polishing cloth was used under the conditions. The number of evaluation sheets was 100, and the average value was used as the evaluation value.

Abrasive grains 0.2μm diamond slurry (0.2% aqueous dispersion)
Drip rate 10mL / min Disk rotation speed 500rpm
Processing pressure 10 N / cm ²
Polishing time 30 seconds The physical properties in the examples were measured by the methods described below.
(1) Fiber apparent density The basis weight was measured by the method of JIS L 1096 8.4.2 (1999), and the thickness was measured with a dial thickness gauge (manufactured by Ozaki Mfg. Co., Ltd., trade name “Peacock H”). The apparent fiber density was calculated from the basis weight value.
(2) Tensile strength, 10% modulus According to JIS L 1096 8.12.1 (1999), a sample having a width of 5 cm and a length of 20 cm is taken, and a tensile speed is measured with a constant-speed extension type tensile tester at a grip interval of 10 cm. The film was stretched at 10 cm / min. The obtained value was converted to the tensile strength per 1 cm width. Further, the strength at 10% elongation in the vertical direction was set to a value of 10% modulus.
(3) Surface roughness The surface roughness was measured by the KES method using a surface testing machine KES-FB4 (manufactured by Kato Tech Co., Ltd.).
(4) Observation of cross section of polishing cloth After cutting the polishing cloth in the thickness direction, the entangled state of the fibers was observed with SEM.
(5) Number of scratches The surface of the polished substrate was observed with a ZYGO interference microscope, and the number of surface scratches of each sample was measured. Scratches with a size of 0.1 μm × 100 μm or more were counted.
(6) Substrate surface roughness (Ra)
The surface roughness of the substrate after polishing was measured with a ZYGO surface roughness measuring instrument (TMS2000).
(7) Measurement of water drop absorption time Using a FACE / CA-A type contact angle assumption device (manufactured by Kyowa Interface Science Co., Ltd.), distilled water is put into a syringe and an injection needle (outer diameter 0.60 mm, inner diameter 0. 0). 45 mm), one drop of water was dropped on the polishing cloth, the water drop was observed from the eyepiece of the device, and the absorption time (tq) was determined by the following equation.

tq = t2-t1 (seconds)
t1: Time when water drops fell on the polishing cloth t2: Time when water drops are sucked into the polishing cloth and there are no water drops on the surface The state of t1 and t2 is visually observed in a normal case (approximately tq is 10 seconds or more). However, if it is very fast or difficult to observe, the state from the time when the water droplet starts to drip from the injection needle to the time when the water droplet is sufficiently absorbed in the polishing cloth by the above-mentioned device is measured. It is possible to measure the whole image of the water drop through the lens after taking a video.

In this way, 20 samples are measured with a sample arbitrarily taken from the product, and the average value of the five largest data among the 20 measured values (tq) is taken. Was the water absorption time value.
(8) Measurement of contact angle Using the same apparatus as described above, measurement was performed in an environment of a temperature of 20 ° C. and a humidity of 60% by a droplet method. In addition, the contact angle was measured using 20 samples as in the measurement of water absorption time, and the average value of the 5 largest data among the 20 measured values was taken. The average value was taken as the contact angle value.

Example 1
A web was prepared through a card and a cross wrapper using sea island type short fibers having a single fiber fineness of 4.4 decitex, 70 islands, and a fiber length of 51 mm, comprising 70 parts of polystyrene as a sea component and 30 parts of nylon 6 as an island component. Subsequently, it processed by 3000 bar / cm < ² > implantation density with the 1 barb type needle punch, and obtained the short fiber nonwoven fabric of the fiber apparent density 0.23g / cm < ³ >. Next, it is immersed in an aqueous solution of polyvinyl alcohol (PVA1) 12% having a polymerization degree of 500 and a saponification degree of 88% heated to about 95 ° C. so as to have an adhesion amount of 25% with respect to the nonwoven fabric weight in terms of solid content. Simultaneously with the impregnation with PVA, a shrinkage treatment was carried out for 2 minutes, followed by drying at 100 ° C. to remove moisture. The obtained sheet was treated with tricrene at about 30 ° C. until the polystyrene was completely removed, and ultrafine fibers having a single fiber fineness of about 0.02 dtex were obtained. Next, after splitting into two pieces perpendicular to the thickness direction using a standard type splitting machine manufactured by Murota Manufacturing Co., Ltd., water having a nozzle diameter of 0.1 mm and a nozzle head with an interval of 0.6 mm is used. The front and back surfaces were treated with a jet punch at a processing speed of 1 m / min at 10 MPa and 20 MPa, and entangled together with the removal of PVA1. At this time, PVA1 was completely removed.

  The ultra-thin short fiber nonwoven fabric thus obtained was made napped with sandpaper, rubbed at 60 ° C. for 20 minutes using a liquid dyeing machine, and then treated with a calender press at 150 ° C. for 5 m / The hair was trimmed after the thickness was compressed to 0.52 times. As a result of observing the cross section of the polishing cloth thus obtained, it was a dense sheet in which ultrafine fibers were entangled with each other, and resinous deposits other than the fiber material were not observed. Table 1 shows the physical properties of this polishing cloth and the results of polishing the substrate A using the obtained polishing cloth.

Example 2
An abrasive cloth was obtained in the same manner as in Example 1 except that polyethylene terephthalate was used instead of nylon 6 as the island component. As a result of observing the cross section of this polishing cloth, it was a dense sheet in which ultrafine fibers were entangled with each other as in Example 1, and resinous deposits other than the fiber material were not observed. Table 1 shows the physical properties of this polishing cloth and the results of polishing the substrate A using the obtained polishing cloth.

Example 3
The substrate B was polished using the polishing cloth obtained in Example 1. As a result, although the numerical values of the surface roughness and the number of scratches were both small, there were many places of poor grinding where irregularities could not be formed on the substrate surface due to insufficient grinding force.

Example 4
The substrate B was polished using the polishing cloth obtained in Example 2. As a result, grinding failure as in Example 3 did not occur, and good texture processing was possible. The results are shown in Table 1.

Comparative Example 1
Using the short fiber nonwoven fabric obtained in Example 1, before removing the sea component, both sides at a processing speed of 1 m / min with a water jet punch composed of a nozzle head having a hole diameter of 0.1 mm and an interval of 0.6 mm before removing sea components. Both were processed at 10 MPa and 20 MPa, and entangled. Next, it is immersed in a 12% aqueous solution of PVA1 heated to about 95 ° C. so as to have an adhesion amount of 25% with respect to the weight of the nonwoven fabric in terms of solid content. And dried to remove moisture. The obtained sheet was treated with trichrene at about 30 ° C. until the polystyrene was completely removed, and then splitted into two pieces perpendicular to the thickness direction using a standard type wood splitting machine manufactured by Murota Manufacturing Co., Ltd. After that, PVA1 was removed to obtain ultrafine fibers having a single fiber fineness of about 0.02 dtex.

  As a result of observing the cross section of the polishing cloth thus obtained, the ultrafine fiber bundles were mainly intertwined, and resinous deposits other than the fiber material were not observed. In addition, the 10% modulus was low, and the shape retention was poorer and the surface was rougher as it was more easily deformed than the polishing cloth obtained in Example 1. Table 1 shows the physical properties of the polishing cloth and the results of polishing the substrate A using the polishing cloth thus obtained.

Comparative Example 2
When the polishing cloth obtained in Comparative Example 1 was rubbed at 60 ° C. for 20 minutes using a liquid flow dyeing machine, a lot of pills were generated on the surface, and tearing occurred in some places. I couldn't.

Example 5
The sheet obtained in Example 1 was subjected to a dip treatment with a polyamide-based hydrophilic agent so that a solid content of 0.5% by weight was given, and then dried and heat-treated at 160 ° C. by dry heat. The obtained sheet had a water droplet absorption time of 10 seconds and a contact angle of 20 °. Table 1 shows the physical properties of this polishing cloth and the results of polishing the substrate A using the obtained polishing cloth. There was an effect that the scratch was reduced as compared with Example 1.

Example 6
The sheet obtained in Example 1 was dipped in a fluororesin so as to give a solid content of 1.0% by weight, then dried and heat-treated at 160 ° C. The obtained sheet had a water droplet absorption time of 200 seconds and a contact angle of 120 °. When the substrate A was polished using the physical properties of the polishing cloth and the resulting polishing cloth, there was an effect that the grinding efficiency was improved as compared with Example 1.

Claims (3)

A short fiber nonwoven fabric is produced by a needle punch method using 1 to 10 dtex short fibers capable of generating 0.0001 to 0.2 dtex ultrafine fibers, and then subjected to ultrathinning, and at a pressure of at least 15 MPa. A method for producing an abrasive cloth substantially made of a fiber material , characterized by performing a raising treatment after performing a high-speed fluid flow treatment. The method for producing an abrasive cloth substantially consisting of a fiber material according to claim 1, wherein the apparent fiber density of the short fiber nonwoven fabric is 0.12 to 0.3 g / cm ³ by the needle punch method. 3. It consists essentially of a fiber material according to claim 1 or 2, characterized in that after the high-speed fluid treatment is performed, a stagnation treatment is carried out, and then a compression treatment is carried out to a thickness of 0.1 to 0.8 times. A method for producing an abrasive cloth.