JP4592300B2 - Non-woven abrasive and manufacturing method thereof - Google Patents

Description

  The present invention relates to nonwoven fabric abrasives, and more particularly to nonwoven fabric abrasives for polishing materials such as metals, plastics, and wood.

  Nonwoven fabric abrasive comprising a substrate such as a nonwoven fabric, an adhesive provided on the surface of the substrate, and abrasive grains at least partially embedded in the adhesive and provided on the surface of the substrate Are known to those skilled in the art.

  Conventionally, in a nonwoven fabric abrasive of a type in which abrasive grains are fixed to a nonwoven fabric with an adhesive, a solvent-based adhesive precursor in which a binder resin is dissolved in a solvent has been mainly used as an adhesive. This is because the aqueous adhesive precursor in which the binder resin is dispersed in water has insufficient polishing power depending on the use of the nonwoven fabric abrasive. However, when the solvent-based adhesive precursor is used, the solvent volatilizes, so there is a problem of adversely affecting the environment and the human body, and it is costly to recover and reuse the volatilizing solvent. There is also a problem.

Therefore, it is desirable to use a water-based adhesive precursor that does not cause such a problem in the manufacturing process of the non-woven fabric abrasive. Therefore, the polishing power of the non-woven fabric abrasive obtained using the water-based adhesive precursor is reduced. There is a demand for improvement to at least the same as that using a solvent-based adhesive.
U.S. Pat. No. 2,958,593 U.S. Pat. No. 4,437,271 Japanese Examined Patent Publication No. 6-71705 JP-T 8-510175 Japanese National Patent Publication No. 10-511749 Japanese Patent Laid-Open No. 9-201232

  The present invention solves the above-mentioned conventional problems, and the object of the present invention is to use a nonwoven fabric abrasive that exhibits a polishing power equivalent to that obtained when a solvent-based adhesive is used while using a water-based adhesive precursor. It is to provide.

The present invention relates to a non-woven fabric abrasive comprising: a non-woven fabric composed of randomly arranged fibers; an adhesive bonded to the surface of the non-woven fabric fibers; and abrasive grains bonded to the non-woven fabric by the adhesive. In
The adhesive is 100 parts by weight of a terminal isocyanate polymer having an anion group uniformly dispersed in water, 1 to 50 parts by weight of a thermosetting acrylic polymer having a hydroxyl group, and 0.01 to 20 parts by weight of a melamine-based crosslinking agent. The nonwoven fabric abrasive | polishing material which is what was induced | guided | derived from the thermosetting aqueous adhesive precursor containing a part is provided, and the said objective is achieved by it.

  The polishing power of the nonwoven fabric abrasive using the water-based adhesive precursor was improved to the same or higher level than that using the solvent-based adhesive.

  The nonwoven fabric used in the present invention is a bulky sheet material composed of randomly arranged fibers. The nonwoven fabric may be any material that is well known to those skilled in the art as a base material for nonwoven fabric abrasives. Representative non-woven fabrics are described, for example, in JP-B-3-55270, column 10, line 10 to column 11, line 25.

  Preferred nonwovens are polyamides (eg nylon 6 and nylon 6,6 composed of polycaprolactam or polyhexamethyladipamide), polyolefins (eg polypropylene and polyethylene), polyesters (eg polyethylene terephthalate), and polycarbonates. It is comprised from such a thermoplastic organic fiber. Nonwoven fabrics composed of nylon and polyester fibers are generally used. The thickness of the fiber is generally about 19 to 250 μm in diameter. Moreover, generally the thickness of a nonwoven fabric is about 2-50 mm.

  An adhesive refers to a material that bonds a nonwoven fabric and abrasive grains. The adhesive may be any material that has sufficient strength to maintain the bond between the nonwoven and the abrasive during the polishing operation. Generally, the adhesive contains a binder resin and, if necessary, an additive as components. The binder resin refers to an organic resin that functions to join substances in order to change from a liquid that can be applied to a rigid solid. The adhesive precursor particularly refers to a flowable composition that can be applied, including an uncured binder resin, an additive, and, if necessary, a solvent.

  In the present invention, the adhesive precursor is water-based. An aqueous adhesive precursor refers to an adhesive precursor mainly containing water as a solvent. In general, a water-based adhesive precursor has a form in which a binder resin is uniformly dispersed in water, and is called an emulsion or a dispersion. Resins that can be uniformly dispersed in water are referred to herein as water-dispersible resins.

  The uncured binder resin needs to be water-dispersible and is preferably thermosetting. This is because it becomes easy to form a nonwoven fabric abrasive by molding. The binder resin preferably exhibits a curing temperature of 100 to 300 ° C, particularly 100 to 200 ° C. When the curing temperature of the binder resin is less than 100 ° C., the curing is insufficient and the abrasive grains are likely to fall off, resulting in a low grinding ratio. On the other hand, when the curing temperature of the binder resin exceeds 300 ° C., the binder resin is decomposed and the abrasive grains are likely to fall off, resulting in a low grinding ratio. The binder resin preferably exhibits a tensile strength of 3000 to 11000 psi, an elongation of 180% or more, preferably 180 to 800%, and a Shore D hardness of 40 or more, preferably 40 to 80 after curing. If the tensile strength of the binder resin after curing is less than 3000 psi, the strength and rigidity of the adhesive after curing are too small to be suitable for nonwoven abrasives, and if it exceeds 11000 psi, the strength and rigidity of the adhesive after curing are too high. It is not suitable for non-woven abrasives. If the elongation of the binder resin after curing is less than 180%, the flexibility of the adhesive after curing is too small to be suitable for a non-woven fabric abrasive, and if it exceeds 800%, the flexibility of the adhesive after curing is too large. Not suitable for nonwoven abrasives. If the Shore D hardness of the binder resin after curing is less than 40, the abrasive grains easily fall off from the abrasive during polishing, and if it exceeds 80, the self-generating action of the nonwoven fabric becomes insufficient.

  Moreover, it is preferable that uncured binder resin does not show adhesiveness even if it touches in room temperature environment. This is because it becomes easy to handle the polishing intermediate material which is obtained by applying the adhesive precursor to the nonwoven fabric and drying it.

  A preferred binder resin is a thermosetting resin containing a terminal isocyanate polymer having an anionic group, a thermosetting acrylic polymer having a hydroxyl group, and a melamine-based crosslinking agent and exhibiting water dispersibility. By combining an isocyanate polymer that is a soft segment and an acrylic polymer that is a hard segment, the characteristics of the binder resin can be optimally adjusted in order to adhere abrasive grains to the nonwoven fabric.

  As a result, the water-based adhesive precursor used in the present invention has the strength to hold the abrasive grains to the same level or higher than the solvent-based adhesive precursor, and prevents the abrasive grains from falling off the nonwoven fabric. The nonwoven fabric can be imparted with an appropriate spontaneous action so that polishing on the polished surface becomes possible.

  The terminal isocyanate polymer having an anionic group, the thermosetting acrylic polymer having a hydroxyl group, and the melamine-based crosslinking agent may be blended in the form of an emulsion or an aqueous dispersion, respectively.

  The terminal isocyanate polymer having an anionic group is a terminal isocyanate polymer having an anionic group in the molecule alone or a mixture thereof and a terminal isocyanate polymer having no anionic group in the molecule, preferably a resin component (anionic group in the molecule). The total amount of the terminal isocyanate polymer having an anion group and the terminal isocyanate polymer having no anion group in the molecule) If the resin has 0.001-0.5 equivalent of an anion group per 100 grams, the water dispersibility of the resin is good. It is preferable because an aqueous dispersion can be obtained without using an emulsifier or a dispersant. Examples of the anionic group include a carboxyl group, a sulfone group, and a combination thereof, and a carboxyl group is preferable.

  The terminal isocyanate polymer having an anionic group in the molecule can be obtained by a conventionally known method. For example, when introduction of a carboxyl group is taken as an example, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, A polyether polyol and / or polyester polyol having a carboxyl group-containing diol unit such as 2,2-dimethylolvaleric acid can be obtained by reacting with a polyisocyanate as a polyol component.

  The polyol component of the polyether polyol and / or polyester polyol used in the terminal isocyanate polymer having an anionic group in the molecule and the terminal isocyanate polymer having no anionic group in the molecule is preferably one having an average molecular weight of 500 to 4000, Further, the polyisocyanate component is not particularly limited, and examples thereof include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate, 1,4-cyclohexylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexyl diisocyanate. And aromatic polyisocyanates such as alicyclic polyisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, etc. , Among them aliphatic or alicyclic polyisocyanate is preferred.

  The terminal isocyanate polymer may be a terminal isocyanate polymer chain-extended with dialkylamine, dialkyl hydrazide or the like, and can be arbitrarily selected depending on the use within a range in which water dispersion is possible. An aqueous dispersion of a terminal isocyanate polymer having an anionic group in the molecule is commercially available, for example, “Bontiter” type, manufactured by Asahi Denka Co., Ltd. -350, HUX-380, HUX-381, HUX-380A, HUX-386, HUX-401, HUX-670, HUX-290H, HUX-290N, HUX-394, HUX-680 and the like.

  The thermosetting acrylic polymer having a hydroxyl group is preferably an acrylic polymer emulsion uniformly dispersed in water. This acrylic polymer has a hydroxyl value of 40-100. When the hydroxyl value is less than 40, there are few reaction points, the reaction becomes insufficient, and the object of the present invention cannot be achieved. On the other hand, when the hydroxyl value exceeds 100, the water resistance of the adhesive after curing is lowered. The acrylic polymer has an acid value of 1-30. If the acid value is less than 1, a stable emulsion is difficult to obtain, and if it exceeds 30, the hydrophilicity of the polymer becomes high, so that the emulsion has a high viscosity and the water resistance of the adhesive is lowered. Furthermore, this acrylic polymer has a glass transition point of −40 to 10 ° C. When the glass transition point is lower than −40 ° C., there are difficulties in the physical strength and durability of the adhesive. When it is higher than 10 ° C., the hardness of the adhesive increases and the flexibility at low temperatures decreases. .

The acrylic polymer emulsion is produced from the following unsaturated monomers.
1. Examples of hydroxyl-containing acrylic monomers include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate, lactone-modified 2-hydroxyethyl acrylate, and lactone-modified 2-hydroxyethyl methacrylate. Hydroxyl group-containing ethylenically unsaturated monomer.
2. As alkyl esters of acrylic acid or methacrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, cyclohexyl acrylate, methyl methacrylate, Ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate and the like.
3. Examples of the α, β-ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, and fumaric acid.
4). Examples of vinyl aromatic compounds include styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, and vinylpyridine.
5). Other vinyl compounds include ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol diacrylate, tetraethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, divinylbenzene, trimethylolpropane triacrylate, and the like.

  These unsaturated monomers include a hydroxyl group-containing acrylic monomer and an α, β-ethylenically unsaturated carboxylic acid monomer as essential components, and if necessary, alkyl esters of acrylic acid or methacrylic acid, and other vinyl compounds. In combination, the type and blending ratio can be appropriately selected and used according to the desired physical properties of the resin.

  Further, as a chain transfer agent for molecular weight adjustment, methyl mercaptan, ethyl mercaptan, isopropyl mercaptan, butyl mercaptan, pentyl mercaptan, hexyl mercaptan, octyl mercaptan, decyl mercaptan, undecyl mercaptan, dodecyl mercaptan, t-dodecyl mercaptan, etc. are used. It is preferable.

  The copolymer contained in the acrylic polymer emulsion of the present invention can be produced according to a known method, for example, using a solution polymerization method, an emulsion polymerization method, or a suspension polymerization method, but is preferably carried out according to emulsion polymerization. . In general, the monomer is present in the presence of a dispersion stabilizer such as a surfactant, and in the presence of a polymerization initiator, for example, a radical initiator for radical polymerization such as ammonium persulfate, preferably 60 to 95 ° C. The reaction is preferably performed for 4 to 8 hours at the reaction temperature, three-dimensionally cross-linked, and neutralized with an amine to obtain the desired acrylic polymer emulsion. The particle diameter of the fine particles in the resulting acrylic polymer emulsion is 50 to 200 nm. Such microemulsions are commercially available, and examples thereof include “Hitaroid” type manufactured by Hitachi Chemical Co., Ltd., product number AE8200, and the like.

  The melamine crosslinking agent may be a known melamine crosslinking agent as a crosslinking agent for synthetic resins. These can be dispersed in water with or without using an emulsifier or dispersant as required. Although it does not specifically limit as a melamine type crosslinking agent, For example, "Melan 5100" by Hitachi Chemical Co., Ltd. etc. are mentioned.

  The blending ratio of these adhesive precursor components is generally 100 parts by weight of a terminal isocyanate polymer having an anionic group, 1 to 600 parts by weight of a thermosetting acrylic polymer having a hydroxyl group, and 0.01 to 100 of a melamine crosslinking agent. Parts by weight. If the amount of the thermosetting acrylic polymer having a hydroxyl group is less than 1 part by weight, the flexibility of the cured adhesive becomes too large due to the characteristics of the terminal isocyanate polymer having an anionic group, which is not suitable for a nonwoven fabric abrasive, 600 If it exceeds the parts by weight, the flexibility of the adhesive after curing becomes too small and it is not suitable for a nonwoven fabric abrasive. If the amount of the melamine-based cross-linking agent is less than 0.01 parts by weight, the softness of the adhesive after curing becomes too large to be suitable for a nonwoven fabric abrasive, and if it exceeds 100 parts by weight, the flexibility of the adhesive after curing will be It becomes too small to be suitable for non-woven fabric abrasives. When processing into a brush-like abrasive, a tackifier such as a terpene resin can be further added to increase the interlayer strength of the brush and improve the durability of the brush. The fine particles of the acrylic polymer emulsion having a particle diameter of 0.01 to 200 nm can be used.

  The abrasive grains used in the present invention are those usually used in the art. Typically, the average diameter may be 4 to 2000 μm, preferably 20 to 1000 μm, and the Mohs hardness is 4 to 10 Mohs, preferably 6 to 9 Mohs. Specifically, particles made of permis, topaz, garnet, alumina, corundum, silicon carbide, zirconia, diamond, and the like can be used. These particles may be mixed in different sizes or may be mixed in different materials.

  The nonwoven fabric abrasive of the present invention can be produced according to methods known to those skilled in the art. For example, first, a binder resin is dispersed in water, or each component of the binder resin dispersed in water is mixed to prepare an aqueous adhesive precursor. An adhesive precursor is applied to the surface of the nonwoven fiber. Abrasive grains are dispersed and adhered onto the applied adhesive precursor. Then, water is evaporated from the adhesive precursor and dried. When a thermosetting resin is used as the binder resin, the adhesive precursor is cured by heating for a certain time. Generally, the adhesive precursor is cured by maintaining at 100 to 300 ° C. for 10 to 30 minutes.

  Abrasive grains may be added in advance when preparing the adhesive precursor, and the adhesive precursor and the abrasive grains may be simultaneously applied to the nonwoven fabric. The drying of the adhesive precursor and the curing of the thermosetting resin may be performed in the same heating process, or may be performed in separate heating processes. Even when the drying of the adhesive precursor and the curing of the thermosetting resin are performed in separate heating processes, the thermosetting resin may be partially cured in the drying process.

  As described above, the nonwoven fabric used as the base material is a bulky fiber material and is highly elastic, so that it can be easily deformed and restored. Therefore, a laminated body in which a plurality of non-woven fabrics are stacked is highly deformable and can be molded relatively freely by applying pressure. In a preferred embodiment of the present invention, a three-dimensional nonwoven fabric abrasive is produced utilizing the easy formability of the nonwoven fabric. A typical example of a three-dimensional nonwoven fabric abrasive is a cylindrical polishing brush having a center hole. FIG. 1 is a perspective view showing a typical configuration form of a cylindrical polishing brush having a central hole. (A) is a laminate format, (b) is a flap format, and (c) is a spiral format.

  FIG. 2 is a schematic view showing a process for producing a polishing intermediate used for producing a three-dimensional nonwoven fabric abrasive. First, the nonwoven fabric 10 is sent out from the nonwoven fabric roll 100. Next, the nonwoven fabric 10 is impregnated with a mixture of an adhesive precursor and abrasive grains. The impregnated nonwoven fabric is heated to fix the thermosetting resin and abrasive grains on the surface of the nonwoven fabric fibers. From there, the adhesive precursor is spray applied.

  Next, water is evaporated from the adhesive precursor in a drying furnace and dried. Drying is performed at a temperature and a time at which the adhesive precursor is non-tacky at room temperature but the thermosetting resin is not completely cured. If the adhesive precursor is still sticky at room temperature after the drying process, it will be difficult to handle and process the resulting abrasive intermediate, and if the thermosetting resin is completely cured after the drying process, This is because it becomes difficult to form the material thereafter. In a preferred embodiment, the drying step is performed at 100 to 120 ° C. for 1 to 10 minutes. After the drying step, the obtained polishing intermediate 20 is not sticky and can be handled. Therefore, it can be rolled up and stored as a roll 200.

  FIG. 3 is a schematic diagram showing a process of manufacturing a three-dimensional nonwoven fabric abrasive using an abrasive intermediate material. First, the polishing intermediate material 20 is sent out from the roll 200 of the polishing intermediate material. Then, the intermediate member 25 is obtained by punching the polishing intermediate member 20 into an appropriate shape. A plurality of intermediate members 25 are stacked using the jigs 6, 7 and 8, and compressed to increase the density. And it heats, compressing, and hardens an adhesive agent precursor completely, and fixes a shape. In a preferred embodiment, the heat curing step is performed at 100 to 200 ° C. for 10 to 60 minutes. Thereby, a cylindrical polishing brush having a central hole is obtained (see FIG. 1A).

  Since the aqueous adhesive precursor is used in the process for producing the nonwoven fabric abrasive material of the present invention, the volatilizing medium is water, which does not adversely affect the environment and the human body, and it is not necessary to recover the volatiles. In addition, water has a lower boiling point than solvents generally used in solvent-based adhesives and requires less energy for drying.

  The following examples further illustrate the present invention in detail but are not to be construed to limit the scope thereof. In the examples, “parts” are based on weight unless otherwise specified.

Each component was blended at a blending ratio shown in Table 1 to prepare an adhesive precursor. This adhesive precursor was applied to both surfaces of the nonwoven fabric shown in Table 2 using a spray method. The dry coating amount of the adhesive precursor was 400 g / m ² .

On the coated adhesive precursor, silicon carbide abrasive grains having an average particle size of 500 μm (manufactured by 3M) were uniformly dispersed and adhered using a scatter method. The coating amount of the abrasive grains was 2300 g / m ² . The material was then placed in an oven and heated at 110 ° C. for 10 minutes to dry the adhesive precursor. In this way, a polishing intermediate material sheet having no tackiness and capable of being handled was obtained.

  This abrasive intermediate sheet was punched out to prepare two abrasive intermediate discs having a diameter of 10 cm. And these grinding | polishing intermediate material discs were piled up, it was set as the laminated body, and it compressed until it became thickness 10mm. The compressed laminate was placed in an oven and heated at 150 ° C. for 30 minutes to completely cure the adhesive precursor.

  The resulting nonwoven fabric abrasive is a polishing wheel having a diameter of 10 cm and a thickness of 10 mm. Polishing was performed by applying a load of 2 kg to the side surface of an iron plate (SPCC-SB) as a polishing piece while rotating the nonwoven fabric abrasive. The polishing speed was 10000 rpm, the polishing time was 30 minutes, 60 minutes, and 90 minutes.

  Before and after polishing, measure the change in weight (g) of the nonwoven fabric abrasive and the change in weight (g) of the abrasive piece, and calculate the grinding ratio (change in the weight of the abrasive piece / change in the weight of the nonwoven fabric abrasive) did. The results are shown in Table 3.

  The change in the weight of the nonwoven fabric abrasive indicates the amount of abrasive grains dropped from the nonwoven fabric abrasive by polishing. The nonwoven fabric abrasive material of the present invention using the aqueous adhesive precursor had a small amount of degranulation and exhibited a grinding ratio equal to or higher than that of the nonwoven fabric abrasive material using the solvent system.

  Such an improvement in characteristics has been confirmed not only in the above-mentioned laminate type polishing disc but also in a polishing brush such as a spiral type and a flap type.

It is a perspective view which shows the typical structure type of the cylindrical polishing brush which has a center hole. It is the schematic diagram which showed the process of manufacturing the grinding | polishing intermediate material used for manufacturing a three-dimensional nonwoven fabric abrasive material. It is the schematic diagram which showed the process of manufacturing a three-dimensional nonwoven fabric abrasive material using an abrasive intermediate material.

Explanation of symbols

10 ... Nonwoven fabric,
100 ... non-woven roll,
20: Polishing intermediate material,
200 ... roll of polishing intermediate material,
25 ... Intermediate member,
6, 7, 8 ... Jig.

Claims (5)

A non-woven fabric abrasive comprising: a non-woven fabric composed of randomly arranged fibers; an adhesive bonded to the surface of the non-woven fabric fibers; and an abrasive bonded to the non-woven fabric by the adhesive,
The adhesive is 100 parts by weight of a terminal isocyanate polymer emulsion having an anionic group uniformly dispersed in water, 1 to 600 parts by weight of a thermosetting acrylic polymer emulsion having a hydroxyl group having a particle size of 50 to 200 nm, and a melamine system. Cross-linking agent 0.01
A non-woven fabric abrasive derived from a thermosetting aqueous adhesive precursor containing ~ 100 parts by weight. The terminal isocyanate polymer having an anionic group is 0.000.00 per 100 grams.
The nonwoven fabric abrasive according to claim 1 , having an anionic group of 1 to 0.5 equivalents, and capable of obtaining an aqueous dispersion without using an emulsifier or a dispersant. The nonwoven fabric abrasive according to claim 1 or 2, wherein the thermosetting acrylic polymer having a hydroxyl group has a hydroxyl value of 40 to 100, an acid value of 1 to 30, a glass transition point of -40 to 10 ° C, and a particle size of 70 to 80 nm. . Heat having hydroxyl groups having a particle size of 50-200 nm, 100 parts by weight of a terminal isocyanate polymer emulsion each having anionic groups uniformly dispersed in water, on the surface of a nonwoven fiber composed of randomly arranged fibers Applying a thermosetting aqueous adhesive precursor and abrasive grains containing 1 to 600 parts by weight of a curable acrylic polymer emulsion and 0.01 to 100 parts by weight of a melamine crosslinking agent;
Drying the adhesive precursor to obtain a non-tacky abrasive intermediate;
Forming the polishing intermediate material; and heating the molded polishing intermediate material to cure the thermosetting resin;
The manufacturing method of the nonwoven fabric abrasive | polishing material containing this. The terminal isocyanate polymer having an anionic group is 0.000.00 per 100 grams.
The method for producing a non-woven fabric abrasive according to claim 4, which has an anionic group in an amount of 1 to 0.5 equivalent and can obtain an aqueous dispersion without using an emulsifier or a dispersant.

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