JPH032632B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an abrasive monofilament that has excellent abrasiveness, toughness, water resistance, chemical resistance, and durability against bending fatigue, and is suitable for use in abrasive applications such as industrial brushes. It has been well known that monofilaments made from synthetic resins containing abrasive particles are used in the field of industrial brushes, etc., and monofilaments made from synthetic resins containing abrasive particles are suitable for use as materials with excellent toughness and spinnability. Polyamides such as nylon 6, nylon 66 and nylon 12 are mainly applied. However, when using an industrial brush to polish, for example, a metal surface, the work is usually done while pouring water or an acidic liquid onto the polished surface in order to remove the heat generated by polishing and furthermore to keep the polished surface clean. However, when abrasive monofilaments mainly made of polyamide are operated in wet conditions, they swell or soften due to water absorption and lose their toughness, which not only reduces the polishing effect but also makes them less durable when exposed to acidic liquids. There is a problem in that the lifespan is likely to be adversely affected. Therefore, when using polyad-based abrasive monofilament in a wet state, it is necessary to take measures that go against energy conservation and brush durability, such as increasing the number of rotations of the brush or increasing the pressing force. Furthermore, it is necessary to adjust the bristles and operating conditions of the brush according to swelling and contraction of the brush, making the work extremely complicated. On the other hand, it is known that polyester, which has better water resistance than polyamide, can be used for polishing monofilaments, but the typical polyester, polyethylene terephthalate, is too rigid.
Not suitable for brush use. Furthermore, polybutylene terephthalate has lower rigidity than polyethylene terephthalate, and although it has excellent brushing properties, it has problems in melt-spinning properties when mixed with abrasive particles, and furthermore, has poor grinding properties. The present inventors conducted studies aimed at obtaining a polyester monofilament for polishing without these drawbacks, and found that polybutylene terephthalate having a specific high melt viscosity was used as the base resin, and abrasive particles were contained therein. It was proposed that monofilament can be stably and efficiently melt-spun and has excellent abrasiveness, toughness, water resistance, and chemical resistance. However, subsequent studies have shown that although this abrasive monofilament using polybutylene terephthalate as a base resin has excellent brush properties as described above, it does not absorb water and is hard. In particular, it has been found that the brush has a disadvantage in that the bristle root portion of the brush, which is a repeated bending portion, becomes brittle and easily breaks around this portion. The durability against bending fatigue becomes more pronounced as the brush grinding conditions become more severe, and this can be said to be a major drawback as an industrial brush material. In order to improve the durability against bending fatigue of the polishing monofilament using polybutylene terephthalate as the base resin, the present inventors continued to study and found that a specific amount of polybutylene terephthalate as the base resin was added. By blending and using polyamide, it is possible to obtain an abrasive monofilament that retains the excellent performance of an abrasive monofilament made only of polybutylene terephthalate and abrasive particles, and has extremely improved durability against bending fatigue. They discovered this and arrived at the present invention. That is, the present invention uses 70 to 95 parts by weight of polybutylene terephthalate having a melt viscosity of 5,000 poise or more and 30 to 5 parts by weight of polyamide having a melt viscosity of 2,000 poise or more.
Furthermore, abrasive particles are added to the mixture consisting of parts by weight.
The present invention provides an abrasive monofilament containing 10 to 50% by weight and melt-spun from the same. The polybutylene terephthalate used in the present invention is substantially obtained by esterification or transesterification reaction of terephthalic acid or its ester-forming derivative and 1,4-butanediol or its ester-forming derivative, followed by polycondensation. It is a polyester, and in small proportions it can contain other dicarboxylic acids such as isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, adipic acid, and sebacic acid, as well as ethylene glycol, propylene cucol, neopentyl glycol, cyclohexanediol, and polyalkylene glycol. Other diols may be included. The polybutylene terephthalate used can also contain customary additives such as heat stabilizers, antioxidants, weathering agents, colorants, lubricants, flame retardants and antistatic agents. Generally, when melt spinning polybutylene terephthalate into monofilament, the melt viscosity is 3000
Polybutylene terephthalate with a relatively low viscosity of less than Poise is used, but when such low viscosity polybutylene terephthalate contains abrasive particles and is melt-spun, the molten material discharged from the spinning nozzle as described above The outflow state of the polymer becomes unstable, causing diaphragm and thread breakage, making it impossible to perform stable melt spinning. However, the present invention is characterized by the use of high-viscosity polybutylene terephthalate, which has a melt viscosity of 5,000 poise or more, particularly 8,000 poise or more, which far exceeds the standards for so-called melt-spinning, and as a result, the abrasive particles The affinity between the monofilament and the polymer is improved, and a monofilament having excellent grinding and abrasive power can be stably and efficiently melt-spun without using an adhesive. There is no particular limit to the upper limit of the melt viscosity of polybutylene terephthalate used in the present invention, but the upper limit of the melt viscosity of polybutylene terephthalate obtained by solid phase polymerization is generally about 30,000 poise, and if the viscosity becomes too high, melt spinning Therefore, it is preferable to use one with a value of 25,000 poise or less. In addition, the melt viscosity as used in the present invention is measured using a Koka type flow tester at a pressure of 20 Kg/cm ² , a mouth diameter of 0.5 mm,
This is a value measured at a temperature of 240 to 250°C. On the other hand, the polyamides used in the present invention include nylon 6, nylon 66, nylon 610, nylon 612,
Mention may be made of melt-spun thermoplastic polyamides such as nylon 11, nylon 12, nylon 6/66 and nylon 6/12, which, like polybutylene terephthalate, can contain customary additives. However, it is desirable that the polyamide used in the present invention has a melt viscosity of 2,000 poise or more, particularly 2,500 poise or more; a melt viscosity of less than 2,000 poise is not preferred because spinnability decreases and the properties of the monofilament become non-uniform. A suitable mixing ratio of the above-mentioned polybutylene phthalate and polyamide is 70 to 95 parts by weight, especially 75 to 90 parts by weight for the former, and 30 to 5 parts by weight, especially 25 to 10 parts by weight (total 100 parts by weight) for the latter. If the polyamide content is less than 5 parts by weight, the durability against bending fatigue of the abrasive monofilament cannot be sufficiently improved, and if it exceeds 30 parts by weight, the water resistance, chemical resistance, toughness, etc. of the abrasive monofilament will be impaired. Otherwise, thread breakage during spinning increases, which tends to make spinning impossible, which is undesirable. The abrasive particles used in the present invention include coke powder,
Alumina-based abrasives such as bauxite and alumina powder, silicon carbide-based abrasives such as white silica and saw powder,
Examples include natural abrasives such as diamond, emery, and garnet, carbide abrasives, zirconia abrasives, and glass abrasives, and two or more of these can be used in combination. The particle size of these abrasive particles is defined by JIS R6001 (1956), and is preferably in the range of #60 to 500, especially #80 to 320. If the particle size is larger than #60, spinnability and monofilament If the toughness is less than #500, the abrasiveness may decrease, which is undesirable. In the present invention, the amount of abrasive particles added is 10% for the additive of polybutylene terephthalate and polyamide.
~50% by weight, especially 15-40% by weight is appropriate;
If it is less than 10% by weight, the desired polishing effect cannot be obtained;
If it exceeds 50% by weight, the toughness and melt spinnability of the monofilament will decrease, which is not preferable. There are no particular restrictions on the method of preparing the composition consisting of polybutylene terephthalate, polyamide, and abrasive particles; for example, the three may be dry blended at once, or abrasive particles may be further added and mixed to a mixture of polybutylene terephthalate and polyamide. Examples include a method in which the material is subjected to an extruder and obtained in the form of pellets, and a method in which it is directly formed into a monofilament without pelletizing. Melt-spinning of the monofilament can be carried out in accordance with the usual melt-extrusion spinning method for polyester, and the monofilament after melt-spinning can be appropriately stretched and heat-set to impart further toughness. There is no particular limit to the diameter of the monofilament, and it can be freely selected by changing the spinneret diameter or setting the drawing conditions depending on the use of the monofilament, but usually a range of about 0.2 to 2.0 mm is appropriate. . Furthermore, compared to conventional monofilaments made of polyamide and abrasive particles, the monofilament of the present invention has the same bending hardness even if it has a smaller diameter, so it can be made thinner than conventional monofilaments, making it easier to use when using a brush. Not only is it economical because the pressing force and rotational speed can be reduced, but it also has the advantage that the polished surface can be finished finely. Thus, the abrasive monofilament of the present invention obtained by stable and efficient melt spinning is strong, does not expand or contract due to water absorption, and has excellent durability against abrasion, grinding force, and bending fatigue. Therefore, the abrasive monofilament of the present invention can be made into a brush shape by bundling, implanting, gluing, entangling, etc., and can be used to polish or grind surfaces such as metal, painted surfaces, wood, stone, and concrete. Industrial brushes have been applied to general household brushes such as kitchen utensils, and have excellent effects. The effects of the present invention will be explained in further detail with reference to Examples below. Example 1 Polybutylene terephthalate (CM1200, manufactured by Toray Industries, Inc.) with a melt viscosity of 6500 and nylon 6 (M1021, manufactured by Toray Industries, Inc.) with a melt viscosity of 2500 were mixed in the proportions shown in Table 1, and further added as abrasive particles. Alumina oxide abrasive with particle size #100 (Morundum A, manufactured by Showa Denko Co., Ltd.)
-40) were dry blended at 20% by weight. Next, the above mixture was melt-mixed using a φ40 mm melt extruder, at a resin temperature of 270°C and an extrusion pressure of 20 Kg/cm ² .
Spun from a nozzle at a discharge rate of 100g/min,
After cooling and solidifying in a cooling water bath at room temperature, it was taken up at a speed of 25 m/min, stretched approximately 3.0 times in a hot air circulation bath at 120°C, and then passed through a hot air circulation bath at 150°C for 5 seconds to heat set. By doing so, a monofilament containing abrasive particles with a diameter of 1.20 mm was obtained. Table 1 shows the results of evaluating the following properties of the obtained monofilament. (1) Bending hardness The maximum load value when a monofilament with a length of 50 mm is placed between two fulcrums with a spacing of 10 mm and a pull-out load is applied to the center, and the sample curves and passes between the fulcrums. (Dry)...Measured after being left in an atmosphere of 20℃ and 65% humidity for 24 hours (Wet)...Measured after immersing a dry sample in water at room temperature for 24 hours (2) Bending recovery rate Monofilament bent 360 degrees was maintained for 3 minutes, and the recovery angle (X°) was measured 1 hour after opening and displayed as X/360×100. (3) Bending fatigue count A load of 1.5 on one end of the fixed monofilament
Kg, and this load side is 180 degrees with a bending angle of 260 degrees.
The monofilament is reciprocated once per minute, and the number of reciprocating movements until the fixed monofilament base is cut is measured. (4) Grinding power A brush with an outer diameter of 270 mm was created by planting monofilament with a bristle length of 35 mm on a brush roll with a width of 200 mm, and using this, the lap amount was 3 mm, 300 rpm,
Under hot water injection conditions, the surface of the iron plate (SS41) was
Measure the amount of grinding (μ) on the iron plate surface after grinding for minutes. As is clear from the results in Table 1, the monofilament (No. 1) made of polybutylene terephthalate abrasive particles has better grinding performance than the monofilament (No. 2) made of nylon 6 abrasive particles. Poor durability against bending fatigue. The abrasive monofilaments (No. 3 to 5) of the present invention, which are made of a composition in which a specific amount of polyamide is blended with abrasive particles to hard polybutylene terephthalate, have excellent bending hardness, water resistance, bending recovery rate, and bending fatigue. The number of grinding times and grinding force are well balanced, and the durability against bending fatigue is particularly improved. However, if the blended amount of nylon 6 exceeds 30 parts by weight (No. 6), it becomes difficult to spin yarn, and polybutylene

[Table] Melt viscosity of terephthalate is too low (No. 7)
The same thing can be said. Example 2 The No. 4 monofilament obtained in Example 1 was
Create a bundle of rotating brushes, rotate them at a rotation speed of 1000 times per minute, and polish by pressing them against the surface of a rusted iron plate while pouring water onto the polished surface. As a result, a beautiful mirror-like polished surface is obtained. The brush was extremely durable.

Claims (1)

[Claims] 1 70 to 95 parts by weight of polybutylene terephthalate with a melt viscosity of 5,000 poise or more and a melt viscosity of 2,000 poise
An abrasive monofilament obtained by melt-spinning a mixture of 30 to 5 parts by weight of polyamide having a polyamide or higher, further containing 10 to 50 parts by weight of abrasive particles.