JPH0158962B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a brush made of a fibrous material made of a mixture of aromatic polyamide having excellent heat resistance and inorganic fine particles.

Brushes are used for applying paint, removing dirt, etc. Efforts have been made to improve the coating efficiency, coating uniformity, cleaning efficiency, cleaning uniformity, durability, etc. of brush materials and structures.

BACKGROUND ART Conventionally, brushes made of natural plant fibers such as tampico fibers and palm fibers have been used for cleaning metal materials such as iron, glass, ceramics, and the like. These have a high bristle density, excellent water absorption, and are characterized by the fact that a fine fibrous uneven surface always appears on the worn surface and is brushed with a certain cleaning effect.
However, it is prone to hair pulling and breakage during use, is easily worn out, has poor durability, and is commercially unstable in supply.

Therefore, in recent years, very thick synthetic fibers with excellent durability such as nylon 6,6, nylon-6, nylon-
Fibers such as 610, nylon-612, polybutylene terecotalate, and polypropylene have come into use, but brushes made of these synthetic fibers have poor cleaning effects (brushing efficiency) and water absorption unless the following improvements are made. (liquid retention) is insufficient.

In order to improve the liquid retention properties of these fibers, methods have been proposed such as bending the fibers into a wave shape, wrapping other thin fibers around the fibers, and making the fibers porous.
By improving the liquid retention, the frictional heat between the brush and the object to be cleaned can be suppressed to a low level due to the cooling effect of the liquid.

On the other hand, in order to improve brushing efficiency, abrasive grains such as alumina or carbon random are often mixed into the fibers to give them apparent heat resistance, hardness, and resuscitation properties on the surface of the brush bristles. There is.

Since the synthetic fibers are made of a thermoplastic polymer with a melting point of 265° C. or less, they have the disadvantage that when brushed for a long time, the bristles of the brush become soft and smooth due to frictional heat, reducing brushing efficiency. Mixing abrasive grains improves brushing efficiency. Improving liquid retention also reduces smoothing caused by frictional heat.

As explained above, brushes using synthetic fibers with improved liquid retention and brushing effects have been put into practical use, but when cleaning objects heated to high temperatures (over 100℃) (This is an unavoidable condition in the manufacturing process of thin plates, etc.), the thermal stability is insufficient, the fibers deteriorate rapidly, and brushes must be replaced frequently. Therefore, there was a drawback that the brush cleaning process accounted for a considerable portion of the manufacturing cost of the object to be cleaned.

If brushes are made from fiber materials with excellent heat resistance, the disadvantage of heat deterioration can be eliminated, but
High hardness materials such as metal fibers are undesirable because they can damage the object to be cleaned. Therefore, it is preferable to use a material that has an appropriate hardness balance with the object to be cleaned and that is made of a tough organic polymer with sufficient heat resistance as a base material and abrasive grains mixed therein.

Most of the heat-resistant organic polymers that are currently in practical use and are produced on an industrial scale are aromatic polyamides (or called fully aromatic polyamides).

In particular, polymetaphenylene isophthalamide is available from Nomex [manufactured by Dupont], Conex
It is sold in large quantities as a fiber under the name [manufactured by Teijin Ltd.]. This fiber has a flexibility comparable to that of conventional organic fibers, and has a limiting oxygen index (Lor) of 27, a melting point of 400 to 410°C, and a decomposition starting point of approximately 400°C, making it difficult to twist. It has heat resistance and is useful as fireproof clothing, bag filters, and insulation materials. Polyparaphenylene terephthalamide is commercially available as a fiber under the name Kevlar (manufactured by Dupont), and this fiber has the same twist resistance as the above-mentioned polymethaphenylene isophthalamide fiber.
It has heat resistance and exhibits high strength and high Young's modulus.
Useful for composite materials, ropes, etc. Various modifications (copolymerization,
Blends, etc.) have been made, and compositions suitable for each purpose have been studied.

However, aromatic polyamides generally have a high melting point, which is close to the decomposition start temperature, so it is impossible to melt-extrude them using a conventional orifice-type melt-spinning device. Therefore, industrially, fibers are manufactured by dissolving the polymer in a solvent and spinning it wet or dry.As a result, only thin fibers can be obtained, and it is difficult to obtain very thick fibers, and even more so, it is difficult to obtain very thick fibers. It was extremely difficult to obtain very thick fibers mixed with

On the other hand, the inventors discovered and proposed that extremely thick aromatic polyamide fibers and aggregates thereof can be obtained by a novel melt-spinning method with high productivity.

Therefore, as a result of conducting research to further improve the invention proposed by the present inventors, we found that an extremely thick aromatic polyamide with inorganic fine particles mixed therein was produced by direct melt spinning from a mixture of aromatic polyamide powder and inorganic fine pieces. The present invention was achieved by discovering that a polyamide fibrous material can be obtained, and that the obtained fibrous material has extremely high heat resistance and moderate hardness, making it an excellent material for brushes with good brushing effects. did.
That is, the present invention provides: ``1(a) substantially formed of a mixture consisting of inorganic particles and an aromatic polyamide; A brush characterized by the ^following : (c) a large number of bundles of the fibrous materials are implanted.

Such a fibrous material can be obtained using the following formula α=Va−Vf/Va×100 [where α is the vacancy rate [%] occupied by a large number of fine fibers in the spinneret, and Va is the vacancy rate [%] occupied by the mesh-like part of the spinneret. Vf is the apparent total volume occupied under unit area, and Vf is the total volume occupied by the mesh-like member surrounding the narrow part under unit area of the mesh-like part of the spinneret. ] A mesh-like spinneret having a large number of closely spaced fibers with a void ratio of about 10% or more is used, and inorganic particles and an aromatic polyamide polymer are coated on the surface opposite to the discharge surface of the spinneret. The polymer is melted while supplying heat from the heat-generating partition member of the mesh spinneret, and the polymer is melted from a large number of fine particles surrounded by the partition member. The melt is extruded, and at this time, a cooling fluid is supplied to the melt discharge surface of the spinneret and the vicinity thereof, and the melt extruded through the narrow tube is taken over while being cooled, so that the melt polymer is substantially It is produced by converting the melt into a number of separate fibrous rivulets and solidifying them within a time without losing their molding ability.

Furthermore, according to the present invention, there is proposed a brush characterized by having a large number of bundles of the fibrous materials described in (a) and (b) implanted therein.

The polymer forming the fibrous material in the method of the present invention may be any so-called aromatic polyamide polymer, and this polymer has the following formula (),
(), () [However, in the formula, () and (), if present, are present in substantially equimolar amounts;
The radicals R ¹ , R ² and R ³ represent the same or different divalent radicals, and at least 50% by weight of the total of R ¹ , R ² and R ³ is aromatic. ] A polymer consisting essentially of at least one type of repeating unit selected from the group consisting of, and these are generally referred to as aromatic polyamides or wholly aromatic polyamides.

R ¹ in the above formulas (), () and (),
R ² and R ³ are the same or different divalent groups, and at least 50% by weight of their total, preferably at least 70% by weight, is an aromatic group. The aromatic group referred to herein means a group having a normal benzene nucleus or a benzene nucleus in a condensed ring, such as benzene, naphthalene, anthracene, etc.

That is, examples of such aromatic groups include paraphenylene group, metaphenylene group, 1,5-naphthylene group, 2,6-naphthylene group, 3,3'-4,
4'- or 3,4'-diphenylene group, 3,3'-4,
4'-, 3,4'-diphenyl ether group, para-xylylene group, meta-xylylene group or para (meth)
Examples include methylphenylene group.

In the present invention, preferred aromatic polyamides include polyparaphenylene isophthalamide,
Polymetaphenylene isophthalamide, polymetaphenylene terephthalamide, poly-1,5-naphthylene isophthalamide, poly-3,4'-diphenylene terephthalamide, polymeta-xylylene isophthalamide, or copolymers thereof, etc. can be given. Particularly preferred aromatic polyamides include polymetaphenylene isophthalamide, polymetaxylylene isophthalamide, (metaphenylene diamine, isophthalic acid chloride, and meta-aminobenzoic acid chloride) copolymers, and the like.

In the aromatic polyamide polymer of the present invention,
Although it is preferable to introduce flexible chain groups such as aliphatic chains into R ¹ , R ² and R ³ in the above formulas (), (), and () from the viewpoint of improving moldability, the ratio of the groups If it exceeds 50% by weight of the total of R ⁴ and R ² , properties such as heat resistance, which are important characteristics of aromatic polyamides, deteriorate, which is not preferable.

Further, in the ultra-thick aromatic polyamide fiber of the present invention mixed with a large amount of a novel inorganic substance, partial crosslinking of the polymer may be partially included. In this case, additional advantages include improved heat resistance of the fibers.

Furthermore, the polymer may contain polymer additives such as antioxidants, heat stabilizers, matting agents, flame retardants, etc., to the extent that important properties such as heat resistance are not lost.

According to the conventional method, these aromatic polyamide polymers are dissolved in a solvent such as dimethylacetamide or N-methylpyrrolidone and then spun. However, in the case of the solution spinning method in which fibers are dissolved in a solvent and spun, it becomes extremely difficult to sufficiently extract and remove the solvent when the target fiber becomes thick. For example, when dry spinning a solution of polymetaphenylene isophthalamide dissolved in a dimethylacetamide/calcium chloride solvent, the solvent in the outer skin of the fiber preferentially escapes, so the outer skin coagulates into a honeycomb structure and the core Significantly inhibits solvent diffusion. Therefore, it becomes more difficult to extract and remove the solvent from the core as the fiber becomes thicker, and it is necessary to make the spinning tube extremely long. The same is true when wet spinning a solution of polymetaphenylene isophthalamide dissolved in N-methylpyrrolidone solvent, which requires extremely long coagulation baths and water washing baths.

What is more undesirable is that the structure of the outer skin and the core are extremely different, resulting in a fiber with an advanced so-called skin-core structure, which deteriorates the physical properties of the fiber, making it difficult to obtain a normal extremely thick aromatic polyamide fiber. I couldn't do it.

According to these solution molding methods, undrawn yarns with a maximum size of about 100 denier (cross-sectional area 0.003 mm ² ) can only be obtained on a trial basis;
Only undrawn yarn of about 0.004 mm ² ) or less can be obtained.

For details on the method for producing extra-thick fibers made essentially of aromatic polyamide, please refer to Japanese Patent Application No. 1983-206068 (1983) filed by the present inventors.
(filed on December 22), the ultra-thick fiber formed from the mixture of inorganic particles and aromatic polyamide according to the present invention has the following formula α=Va−Vf/Va×100 [where α is the diameter of the spinneret Va is the vacancy rate [%] occupied by a large number of fine particles, Va is the apparent total volume occupied under the unit area of the mesh-like part of the spinneret, and Vf is the vacancy rate [%] occupied by the mesh-like part of the spinneret. This is the total area occupied by the mesh-like member surrounding the narrow part. ] A mesh-like spinneret having a large number of closely spaced fine particles with a void ratio of about 10 or more is used, and inorganic fine particles and an aromatic polyamide polymer are applied to the surface opposite to the discharge surface of the spinneret. The polymer is melted while supplying heat from the heat-generating partition member of the mesh spinneret, and the polymer is melted from a large number of fine particles surrounded by the partition member. The melt is extruded, and at this time, a cooling fluid is supplied to the melt discharge surface of the spinneret and the vicinity thereof, and the melt extruded through the narrow tube is taken over while being cooled, so that the melt polymer is substantially It can be produced by converting the melt into a number of separate fibrous rivulets and solidifying them within a time without losing the ability to form moldings.

The major feature of this manufacturing method is that a well-mixed mixture of inorganic particles and aromatic polyamide polymer powder is fed to a mesh-like spinneret that generates heat, and is melted into fibers in an extremely short time. However, such a spinning method was not known in the past.

Mixing of the inorganic particles and the aromatic polyamide polymer powder is usually carried out using equipment such as a ball mill, a vibration mill, a jet mill, a planetary type stirrer, a kneader, etc., which are known for mixing powders. Advantageously, grinding and mixing are carried out simultaneously.

The aromatic polyamide polymer powder can be obtained by a known interfacial polymerization method, and it is preferable to use fine particles having a diameter of 1 μm or less obtained by this method. Usually, such fine particles are secondary agglomerated to form a powder having a diameter of several 10 to several 100 μm. In the present invention, even such agglomerated powder can be suitably used.

In order to obtain a fibrous material in which inorganic particles are uniformly dispersed, it is preferable to crush the particles of secondary agglomerated units of the polymer as much as possible so that the polymer particles adhere to the surface of the inorganic particles. A small amount of paraffin, silicone oil, etc. can also be mixed in to promote adhesion. Generally, it is easier to mold and obtain a uniform fibrous material by mixing inorganic particles and polymer particles in as small a unit as possible.

Inorganic particles used in the present invention include, for example, calcium carbide, titanium oxide, kaolin, clay, talc, diatomaceous earth, potassium titanate, feldspar, mica, glass powder, graphite, carbon black, molybdenum dioxide, metal powder (e.g. , copper powder, aluminum powder, iron powder, chromium powder, nickel powder), γ
-Fe ₂ O ₃ , silicon carbide, alumina, zeolite, ceramic materials for sintering, and the like. Suitable inorganic pieces are selected depending on the intended use of the fibrous material of the present invention. For example, when used in polishing brushes, hard inorganic pieces such as silicon carbide and fused alumina are preferably used.

The shape of the inorganic pieces used in the present invention may be spherical, polyhedral, acicular or irregular.
Preferably, the particle size is such that it passes through a sieve of at least 20 mesh, more preferably a particle size that passes through a sieve of 500 mesh. However, even if the particles are apparently large, they may be pulverized to the above-mentioned mesh size during the mixing process with the aromatic polyamide powder. The maximum particle size is usually around 50,000 mesh.

If the inorganic particles have a needle-like or elongated shape (aspaku ratio is about 5 or more), the minimum cross-sectional area is 1 mm ² to 2.5 × 10 ^-7 mm ² , preferably 2.5 × 10 ^-3
It may be in the range of mm ² to 2.5×10 ^-7 mm ² , and its longest strip length is 5 mm to 0.0005 mm, preferably 0.25 mm.
Any material in the range of mm to 0.0005 mm is sufficient.

The inorganic pieces are added and mixed in a volume ratio of 2 to 250, preferably 10 to 100, to 100 parts of the aromatic polyamide powder to give a fibrous material in the same proportion as the mixed amount. If the amount is less than this amount, the effect of adding the inorganic pieces will not be apparent, and if it is more than this amount, the moldability will deteriorate and the holding power of the inorganic pieces of the aromatic polyamide will decrease, causing the inorganic pieces to come off. or the fibrous material may break easily. Further, in order to increase the adhesion between the inorganic pieces and the aromatic polyamide, the surface of the inorganic pieces can be treated with a coupling agent or the like.

In order to produce a fibrous material having this composition from the mixture of inorganic particles and polymer powder described above, except for using this mixture, the ultra-thick aromatic polyamide fiber previously proposed by the present inventors can be used. The manufacturing method is basically the same as the manufacturing method (Japanese Patent Application No. 56-206068, filed December 22, 1981).

In particular, the size (area) of the threads in the mesh-like spinneret is preferably in the range of 0.023 to 16 mm ² , more preferably 0.06 to 2 mm ² . The width of the narrow strip is preferably 0.15 to 4 mm, more preferably 0.25 mm.
A range of ~1.3 mm is advantageous.

When a plain woven wire gauze is used as the mesh-like spinneret, it is advantageous to use a wire gauze preferably in the range of 6 to 90 meshes, more preferably in the range of 14 to 50 meshes. Too small value mesh (large thin area)
In this case, the shape of the molded product is too large and the amount of heat transferred from the die to the polymer/inorganic pieces is too small. Messengers with too large values (small details)
area), the shape of the molded product is too small;
The strength of the base is no longer sufficient.

The mesh-like spinneret used for producing the fibrous material of the present invention may be a twill wire mesh in addition to a plain wire wire mesh, and a large number of microscopic metal spheres are sintered to form a large number of thin wires. It may also be a thin sintered body. Furthermore, the partition member existing between adjacent narrow spaces may be an etched perforated plate having recesses.

In the present invention, these mesh-like spinnerets can be used not only alone, but also in combination and laminated.

Among these spinnerets, according to the present invention, preferably, the discharge surface of the spinneret has a large number of narrow partition members partitioned by narrow partition members having uneven portions, and A mesh-like spinneret is used, which is structured so that the melt extruded from one slot can communicate with the polymer melt extruded from another adjacent slot through the recess of the partition member.

In the above formula expressing the void ratio that defines the mesh-like spinneret used in the method of the present invention, Va is the apparent total volume occupied under a unit area of the mesh-like part of the spinneret, and Vf is the apparent total volume of the mesh-like part of the spinneret. This is the total area occupied by the partition member surrounding the narrow part under the unit area of the mesh-shaped part.

Assuming virtual surfaces that come into contact with the front and back surfaces of the spinneret, the unit area of these two virtual surfaces (1 cm ² )
The volume of the enlarged part is defined as the apparent total volume (Va) of the above formula ().

It will be easily understood that in the case of a laminated mesh spinneret, the apparent total volume (Va) is determined assuming a virtual surface in the same manner as described above.

Regarding actual mesh-like spinnerets, Va
To determine Va, Va can be easily determined by measuring the thickness of the mesh spinneret with a dial gauge having a contact surface of 1 cm ² .

Also, for a certain mesh-like spinneret, Vf
In order to determine this, it is sufficient to cut a mesh-like spinneret into a predetermined area, immerse it in a liquid, and measure the increased volume. The value obtained by converting this increased volume per 1 cm ² of the mesh-like spinneret is Vf. The mesh-like spinneret has a vacancy rate (α) expressed by the formula () of about 10% or more, preferably about 25% to about 90%.

Further, the mesh-like spinneret used in the method of the present invention is about 10 mm or less, more preferably about 0.1 to about 5 mm.
mm, particularly preferably from about 0.2 to about 2 mm.

The partition member of the spinneret used in the method of the present invention is in a state where heat is generated to melt the powdered polymer supplied as described above.

In order to generate heat from the partition member itself,
A method in which the partition member is heated by passing an electric current through it (current heating method), a method in which a high-frequency electric field is applied and heated by induction heating method, a method in which the partition member is constructed of thin tubes and heated by flowing a heating medium through the thin tubes (thermal fluid heating method) heating method) etc. are advantageously employed.

Materials that can be used in the current heating method and induction heating method include platinum, gold, silver, copper, titanium, vanadium,
Tungsten, iridium, molybdenum, palladium, iron, nickel, chrome, cobalt, lead,
Metals such as zinc, bismuth, tin, aluminum, stainless steel, nichrome, tantalum,
Alloys such as silver, phosphor bronze, and duralumin,
Inorganic compounds that primarily exhibit semiconductor properties, such as graphite, silicone, germanium, selenium, tin oxide, indium oxide, iron oxide, and nickel oxide;
It is advantageous to use a spinneret formed with a substance having a specific resistance of about 10 ^-7 to ^{10 9} Ωcm, such as an organic compound exhibiting semiconductor properties such as polyacetylene and polyphenylene.

Other examples include a structure in which the surface of a glass sphere bead is coated with silver and brought into contact with pressure to make it conductive; a conductive cap structure in which a metal such as aluminum is evaporated onto a ceramic fiber such as alumina or zirconia and then pressure-formed; and a porous ceramic cap. Examples include a conductive mesh spinneret structure in which a plate is immersed and deposited in a graphite particle dispersion, and various other possible structures can be modified and implemented.

The conductive mesh-like spinneret thus obtained can be used in an electric field of 0.1 to several hundred V/cm in the case of the current heating method.
A current of 0.1 to several hundred A is applied, and 0.1 to several thousand W/cm ²
watt densities, but these values may vary depending on the intended use.

The conductive mesh spinneret for the current heating method is attached to the extruder, and should be installed in such a way that the desired current flows through the conductive mesh spinneret. The conductive mesh spinneret and the extruder may be insulated, or the extruder and the conductive mesh spinneret may be electrically connected so that the current flowing to the extruder and the current flowing to the conductive mesh spinneret are controlled. It is also possible to obtain the desired performance by allocating it to

The insulating material for insulating the conductive mesh spinneret and the extruder may be a combination of a general ceramic plate and an inorganic adhesive such as silica, alumina, or zirconia.

On the other hand, when heating a conductive mesh-like spinneret as described above by an induction heating method, a coil is generally arranged approximately parallel to the spinneret, and a magnetic field approximately perpendicular to the spinneret is applied to the spinneret. Eddy currents are generated and Joule heat is generated. If the heating frequency is selected to be high, the penetration of eddy current becomes shallow due to the skin effect, and local heating of only the surface can be performed. The coil arrangement, magnetic field strength,
Optimal conditions can be obtained by appropriately combining frequencies.

The material of the spinneret that can be used in the dielectric heating method is generally a substance that causes dielectric loss, and it depends on the frequency of the applied electric field and the nature of the polymer to be formed.
Examples include ceramics with polar groups.

When heating such a dielectric mesh spinneret using a dielectric heating method, an electrode is usually arranged parallel or perpendicular to the surface of the spinneret, and an alternating electric field parallel or perpendicular to the surface of the spinneret is applied. Loss occurs and heat is generated.

The narrow width of the mesh-like spinneret depends on its material and heat transfer efficiency between the polymers, but is preferably
It ranges from 50μ to 3mm, preferably from 100μ to 1mm. If the narrow strip is too narrow, it will be difficult for a high viscosity polymer to pass through, and if the narrow strip is too wide, the polymer will not be heated properly or unevenly, which is undesirable.

The polymer needs to pass through the narrow group of mesh-like spinnerets within a period of time without losing its ability to form a molded article. If the time for passing through the narrow group is too long, the ability to form a molded article will be lost, and if it is too short, the polymer cannot be heated to an appropriate temperature, so there is an optimum range of passing time. This range depends on the type of polymer, the temperature and thickness of the mesh-like spinneret, the size of the slivers, the discharge rate, etc.

The extremely thick fibrous material obtained by the above-mentioned method has irregular and periodic changes in cross-sectional area along its length, and the intrafiber cross-sectional area variation coefficient as defined below. It is characterized in that [CV(F)] is in the range of 0.05 to 1.0. The CV(F) of fibers obtained by conventional orifice spinning is
Less than 0.05. This CV(F) means that when the fiber is cut at intervals of, for example, 1 mm along its length, the size of each cross-sectional area varies randomly; There are irregular cycles,
It also means that the width of the fluctuation is within a statistically constant range.

The coefficient of variation of the intrafiber cross-sectional area [CV(F)] here refers to the variation in fineness in the longitudinal direction (axial direction) of the fiber, and is the coefficient of variation of the fiber cross-sectional area in the fiber aggregate. , select an arbitrary 3 cm area, measure the size of the cross-sectional area at 1 mm intervals by microscopic observation, and calculate the average value of the 30 cross-sectional areas ()
and the standard deviation (σA) of the 30 cross-sectional areas,
It can be calculated from the following formula.

CV(F)=σA/ Each fiber constituting the very thick fiber aggregate formed from the mixture of the inorganic fragments obtained by the method described above and the aromatic polyamide has a CV(F)F) in the range of 0.05 to 1.0. Especially 0.08~0.7, especially 0.1~0.5
Preferably, the range is .

Furthermore, regarding the extremely thick fiber aggregate formed from a mixture of inorganic fragments and aromatic polyamide, the aggregate is made of a large number of fibers constituting the aggregate, and is bundled in a direction perpendicular to the fiber axis at any position of the aggregate. The variation in the cross-sectional area of each fiber when the body is cut is expressed as the fiber cross-sectional coefficient of variation within the bundle [CV(A)], which is 0.1 to
Another major feature is that CV(A) is in the range of 0.2 to 1.

This CV(A) is calculated by randomly extracting 100 fibers from the above aggregate, rolling them together to form a bundle, and cutting the bundle in a direction perpendicular to the fiber axis at an arbitrary position. Measure the size of each cross section by observing the cross section with a microscope, and calculate the average value () and the
It can be calculated by finding the standard deviation (σB) of 100 cross-sectional areas and using the following formula: CV(A)=σB/.

The cross-sectional area of the ultra-thick fibers made essentially of the mixture of inorganic particles and aromatic polyamide of the present invention ranges from 0.01 to 5 ^mm2 on average, preferably from 0.05 to 1 ^mm2 .
is within the range of If this cross-sectional area is smaller than 0.01 mm, the fiber will not have sufficient bending elasticity and will not be suitable for use as extremely thick fibers such as cleaning brushes. On the other hand, the cross-sectional area is 5
If it exceeds mm ² , various advantages as a fiber, such as bending elasticity under moderate force, will be reduced, making it unsuitable for use as a brush.

The fibers of the present invention have extremely high heat resistance and high bending elasticity even in an unstretched state. However, further stretching and heat treatment can be carried out in the same manner as conventional fiber treatments, thereby further improving heat resistance and bending elasticity.

According to the above-described method for producing the fibers of the present invention, fibers with a non-circular cross section can be easily obtained. It is possible to create a brush with improved brushing efficiency due to the corner-grabbing effect of the non-circular cross-section fibers.

The degree of non-circularity of the fiber cross-section is determined by the circumference 2
It can be expressed by an irregularity coefficient expressed as the ratio (D/d) of the maximum distance between parallel lines (D) and the minimum distance (d) between two circumscribed parallel lines. The ultra-thick aromatic polyamide fibers of the brushes of the present invention usually have a profile factor (D/d) of at least 1.1, and most have a deformation factor (D/d) of at least 1.2.

Furthermore, the fiber formed from the mixture of inorganic particles and aromatic polyamide used in the present invention is characterized in that the above-mentioned deformation coefficient (D/d) changes along the length direction of the fiber. There is. In other words, the fiber has a maximum difference in shape coefficient [(D/d) max] and a minimum shape coefficient [(D/d) mm] in any 30 mm range along its length. (D/d) max - (D/d) mm]
is usually at least 0.05, preferably at least 0.1. The method for measuring and calculating the irregularity coefficient and the maximum difference in irregularity coefficient is described in detail in Japanese Patent Laid-Open No. 140110/1983.

High performance brushes can be made from the fibers of the present invention.

The fiber length (hair length) of the brush of the present invention is 10 mm.
~100mm is suitable, more preferably 20mm~60
mm. In general, when the fiber cross-sectional area is large, the longer the hair length is, the more preferable, and when the fiber cross-sectional area is small, the hair length is preferably shorter. The shorter the length of the bristles, the stronger the bending resistance, repulsion, and elasticity, which improves brushing efficiency, but if the bristles are too short, the substrate of the brush may rub against the object to be cleaned when too much brush pressure is applied. Undesirable. On the other hand, if the hair length is too long, the cleaning effect will be poor and the durability will be short. However, if the bristles are long, the brush can be regenerated (brush trimmed to match), and the brush can be replaced less frequently.

The brush fibers of the present invention have excellent bending resistance and repulsion properties, and are characterized by good brushing efficiency even when the length of the bristles is considerably long.

The brush of the present invention is mostly used for cleaning purposes, and it is preferable that the fibers be spaced as closely as possible. If So is the area of the area where the fibers are actually flocked in the fiber bundle, and S ₁ is the sum of the cross-sectional areas of the fibers that are flocked in that part, then the ratio expressed as S ₁ /So (called the filling ratio) is 0.15S. It is advantageous to satisfy the range ₁ /So<1.0, particularly preferably the range 0.3S ₁ /So<0.95.

In order to make this filling ratio close to 1.0, the fibers are preferably square, regular triangular, regular hexagonal, etc. rather than circular. The above-mentioned manufacturing method is preferable because the polyhedron described above can be easily obtained.

There are various methods for implanting fibers into a substrate, and various methods have been devised to efficiently make brushes. There are methods such as making a hole in the substrate and filling it with the fiber bundle and gluing the base, or surrounding the base of the fiber bundle with a channel and fixing it by bending both sides of the channel inward.

There are various types of flocking distribution, such as when fibers are flocked evenly, when fibers are flocked in bundles, and when fibers are flocked in stripes (parallel or intersecting). In the above-mentioned calculation of the filling rate, So means the area of the root area of the bundles or streaks when the hair is transplanted in the form of bundles or streaks, and the area of the space between the bundles or streaks is Not included. The brush thus created can be used as is or attached to a roller or the like.

For cleaning purposes, channel type, desk type,
Half-desk type, spring type, U-shaped bending type, ring type, etc., which are attached to a roll, and standard brushes, twisted brushes, cylindrical brushes, umbrella-type brushes, cup brushes, foil brushes, etc., which are used alone. It can take the form of a brush.

The brush of the present invention thus obtained has excellent heat resistance and excellent brushing efficiency, so it is suitable for conventional methods such as removing high-temperature metals such as steel (cleaning of drawing plates and drawing rollers, cleaning of thin iron plates), etc. It is suitable for use in areas where brushes made of other materials cannot be satisfied. Furthermore, since the brush of the present invention does not easily reduce its brushing efficiency (has good durability), it can be used for a long period of time even in general-purpose applications, making it economical.

A part of the present invention will be described in detail through Examples.

In addition, the intrinsic viscosity (IV) in the examples is based on the following formula.

IV=lnηrel/0.5 (However, ηrel is the value obtained by dividing the viscosity of a 0.5 g/100 ml solution of the polymer at 25°C in a capillary viscometer by the viscosity of the solvent determined using the same viscometer. ) In the examples, "parts" means "parts by weight." % also means % by weight.

In addition, the average particle diameter in Examples means the diameter of a circle having an area equal to the average value (n = 30) of the area of the two-dimensional projection line of the particles determined from a photo taken with an optical microscope or an electron microscope. .

Example 1 Polymetaphenylene isophthalamide obtained by polymerizing metaphenylene diamine and isophthalic acid chloride in the presence of tetrahydrofuran/water (IV measured in N-methylpyrrolidone (NMP) is 1.0)
A dry polymer with an average particle diameter of 35 μm, which is formed by secondary aggregation of particles with an average particle diameter of 0.5 μm, and alumina particles with an average particle diameter of 50 μm are mixed in a ball mill in a one-to-one ratio. The powder mixture obtained was pushed through a plunger-type extruder (the extrusion surface was a rectangle of 1 cm x 10 cm, and the stroke length of the plunger was 20 cm) maintained at 340 °C and installed at the bottom of the extruder. 20 mesh plain weave wire mesh (wire diameter 0.42mmφ, mesh size 0.85×0.92mm,
(made of stainless steel) and the wire mesh has approx.
A current of 5.0 W/cm ² is applied to melt and discharge the polymer powder, and cooling air is blown at a speed of about 0.2 m/sec toward the discharge side surface of the wire mesh to form a fibrous rivulet. The fibers were drawn at a speed of 0.5 m/min to obtain a mixed fiber aggregate of alumina and polymetaphenine isophthalamide, which consisted of fibers with a side of about 350 μm (cross-sectional area of 0.123 mm ² ) and a substantially square cross section.

The average strength, elongation, and initial Young's modulus of the single yarn of this fiber aggregate (undrawn, untreated yarn) are each 1.2.
g/de, 20%, 1050Kg/ ^mm2 . Also CV(F)
was 0.17, CV(A) was 0.18, and the average value of D/d was 1.4.

In addition, a single yarn was selected from this fiber aggregate and 5 cm
When the length is held horizontally with a cantilever and a load of 53.5 mg is suspended from the tip, the displacement of the tip is 0.3 cm on average for the three samples, and when the load is removed, it completely returns to its original position. Ivy. The bending rigidity EI was calculated from the relationship of the load change position and was found to be 7280 dine cm ² , which can be said to have sufficient stiffness and recovery power as a fiber material for brushes.

Next, cut the obtained fiber aggregate into lengths of 12 cm.
Arranged at a linear density of 480 lines/cm, folded at the center,
Using that part as the root, I sandwiched it with a 1cm wide channel. (Thus, the packing density (S ₁ /So) is 0.59.) The ends of the hair were trimmed so that the distance between the channel and the ends was 5.0 cm.

Next, fix this brush (width 10cm) and set the radius to 10
A steel disk at 210°C with scales attached and rotating at 500 revolutions per minute was brought into contact with the brush at a distance of 4.9 cm from the channel. The scale was easily removed. Next, when I replaced it with a similar iron disk and brushed in the same way, the performance of the brush did not deteriorate.

Example 2 Particles with an average diameter of 1 μm of polymethaxylene isophthalamide (IV measured in NMP is 0.7) obtained by polymerizing metaxylylene diamine and isophthalic acid chloride at the tetrahydrofuran/water interface are secondary agglomerated. A 1:1 mixture of dried polymer powder particles with an average particle size of 200 μm and carborundum particles with an average particle size of 1 μm was pressed in a plunger type extruder at 250°C as in Example 1, and heated to 60°C.
The polymer powder is supplied to a mesh flat wire wire mesh (made of stainless steel, wire diameter 0.21 mm), a current of about 5 W/cm ² is passed through the wire mesh, the polymer powder is melted, and the polymer powder is discharged from between the meshes of the wire mesh. At the same time, cooling air at a speed of about 0.5 m/sec was blown toward the discharge side surface of the wire gauze to form a fibrous stream.
A nearly square cross section of 110 μm (therefore the cross section is
A polymethacrylene isophthalamide fiber aggregate having a diameter of 0.012 mm ² ) was obtained.

This fiber aggregate was further heat-treated at 280° C. for 1 hour according to a regular schedule. The average strength, elongation, and initial Young's modulus of the single yarn were 1.3 g/de, 25%, and 1200 Kg/mm ² , respectively. Also, CV(F) is 0.15, CV(A) is 0.16, D/d
The average value was 1.4.

The bending rigidity obtained in the same manner as in Example 1 is
It was 150dyne・^cm2 .

Next, cut the obtained fiber aggregate into 6 cm lengths and cut them 1 cm from the root so that the packing density (S ₁ /So is 0.65).
A brush was obtained by cutting off the part and attaching it to a thick twisted wire.

This brush did not change in quality even when left on an iron plate heated to 200°C for a long time, and was suitable for finishing the surface of a hot iron plate.

Example 3 Obtained by polymerizing 42.5 parts of metaphenylene diamine, 42.5 parts of isophthaloyl chloride, and 15 parts of hydrochloride of meta-aminobenzoyl chloride at the tetrahydrofuran/water interface (IV measured in NMP is 0.9). Particles with a diameter of 0.6 μm aggregate and the average particle diameter
Dried copolymer powder (metaphenylediamine, isophthaloyl chloride and meta-aminobenzoic acid chloride) with a diameter of 100 μm and an average particle size of 40 μm.
A mixture of 1:2.5 m of iron powder was mixed in a vibrating mill using the same extruder as in Example 1, and was lined with 30 meshes of plain-woven wire mesh, with a thickness of 3 mm, and a hole with a minimum area of 3 mm when viewed from the discharge surface. Using a device equipped with a 6.0 mm ² mesh die, the fibers were converted into ultra-thick fibers with an average cut surface area of 4.5 mm ² .
Before extrusion, the powder was heated at 280℃ for 5 minutes, 250kg/
It had been pre-solidified in the extruder under conditions of cm ² . Further, a current of 13 W/cm ² was applied to the mesh cap, and a current of 6 W/cm ² was applied to the 30-mesh plain-woven wire mesh.

The obtained fiber aggregate was cut to a length of 10 cm, and was evenly buried in an uncured epoxy resin plate so that the packing density (S ₁ /So) was 0.3, and the epoxy resin was cured to obtain a brush. Ta.

This brush can be used regularly at 200℃ and can be used for cleaning the inner walls of high temperature tanks.

Reference Example 1 A brush having the same shape as in Example 1 was obtained from drawn and heat-treated bristles made of nylon 6,6 containing 45% alumina and having a cross-sectional area of 0.13 mm ² and an average particle size of 50 μm. Then, the iron disk was brushed in the same manner as in Example 1. When the temperature of the iron disk was 120°C, the fibers of the brush gradually turned yellow and became brittle. Furthermore, when the temperature of the iron disk was 200°C, the tips of the bristles shrunk significantly, making it unusable.

Example 4 Polymer powder similar to Example 1 and an average particle size of
85 μm calcium carbonate was mixed in a ball mill at a ratio of 4:6, and the mixture was made into fibers in the same manner as in Example 1 to obtain a fibrous material with an average cross-sectional area of 0.25 mm ² .

Example 5 A fibrous material with an average cross-sectional area of 0.25 mm 2 was prepared by mixing 40% potassium titanate short fibers (manufactured by Otsuka Chemical Co., Ltd.) into the same polymer powder as in Example 1 and using the same method as in Example ¹ . I got it.

Example 6 The same polymer powder as in Example 1 had an average particle size of
A fibrous material having an average cross-sectional area of 0.20 mm ² was obtained in the same manner as in Example 1 by mixing 35% of 40 μm glass beads.

Claims (1)

[Scope of Claims] 1 (a) substantially formed of a mixture consisting of inorganic particles and an aromatic polyamide; (b) said mixture having an average area of cut surfaces cut perpendicularly along the fiber axis; A brush comprising a fibrous material having a size of 0.01 to 5 mm ² , and (c) having a large number of bundles of the fibrous material implanted therein.