JP2000355844A - Mesh cloth and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mesh cloth excellent in mechanical properties, dimensional stability and handling property, also constituted with a thin diameter fibers, having a large opening rate and useful for a filter, etc. by removing a sheath component of a woven or knitted article containing a specific sheath core type composite monofilament. SOLUTION: This mesh cloth having 30-70% opening rate, is obtained by removing a sheath component of a woven or knitted article containing a sheath core type composite monofilament (having preferably <=25 μm diameter) constituted by a core component of a molten liquid crystalline polyester (its melting point is preferably 270-350 deg.C) consisting of a recurring unit e.g. p-oxybenzoic acid, and a sheath component of an easily soluble polymer such as an easily alkali soluble polyester. Further, a screen gauze excellent in printing characteristics is preferably constituted of the mesh cloth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mesh cloth and a method for producing the same, and more particularly, to a screen cloth and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, mesh cloths made of metal wires, synthetic fibers, and the like have been used for filters, screen gauze, and the like. It is necessary to reduce the opening diameter of the mesh cloth in order to increase the printing accuracy, filtration accuracy, and the like. However, even if the opening diameter is reduced, it is desirable that the opening ratio (the ratio of the portion where no fiber exists) is small. Effect cannot be obtained. That is, although the fiber portion in the mesh cloth plays a role of partitioning the mesh cloth (forming an opening having a desired opening diameter), the fiber existing portion itself does not perform a printing function, a filtering function, and the like. The higher the proportion of the fiber present portion, the lower the functions of the mesh cloth. In the case of using a fiber having a large wire diameter, if the opening diameter of the mesh cloth is reduced, the opening ratio is necessarily reduced accordingly. Therefore, in order to obtain a mesh cloth having a small opening diameter and a high opening ratio, it is necessary to reduce the diameter of the constituent fibers.

[0003]

However, although the use of small-diameter fibers makes it possible to obtain a mesh cloth having a small opening diameter and a large opening ratio, the small diameter reduces the strength of the fibers themselves (a value not converted into denier). Inevitably drops. Therefore, when the opening ratio is increased (when the fiber density is decreased), the mechanical performance and dimensional stability of the mesh cloth become insufficient, and the opening diameter of the mesh cloth also varies, so that desired performance cannot be obtained.

[0004] From the above, mesh cloths using stainless fine wires which are extremely excellent in mechanical performance have been used for applications requiring extremely high accuracy.
Mesh cloths are heavy, have low handling properties, and are inferior in workability in the manufacturing process and the like, and there is a limit in reducing the diameter.
An object of the present invention is to provide a mesh cloth which is excellent in mechanical performance, dimensional stability, handleability, is composed of fine fibers and has a large opening ratio, a method for producing the same, and excellent printing characteristics using the mesh cloth. It is to provide a screen gauze and a manufacturing method thereof.

[0005]

The present invention relates to (1) a woven or knitted fabric composed of a monofilament made of a molten liquid crystalline polyester, wherein the monofilament has a diameter of 40 μm or less and an opening ratio of 30 to 75%. (2) Removes the B component of the woven or knitted fabric containing a core-sheath composite monofilament whose core component is composed of a molten liquid crystalline polyester (component A) and whose sheath component is an easily soluble polymer (component B). Mesh cloth obtained by
(3) The mesh cloth according to (1), wherein the aperture ratio is 50% or more, (4) the diameter of the monofilament is 25 μm.
m or less, the mesh cloth according to (1),
(1) A screen gauze made of the mesh cloth according to any one of (1) to (4), (6) a core component composed of a molten liquid crystalline polyester (A component), and a sheath component composed of a readily soluble polymer (B component). A method for producing a mesh cloth for removing the B component of a woven or knitted fabric containing a core-sheath composite monofilament,
(7) The core component is a molten liquid crystalline polyester (A component),
The present invention relates to a method for producing a screen gauze for removing a component B of a woven or knitted fabric containing a core-sheath composite monofilament whose sheath component is composed of an easily soluble polymer (component B).

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, in the present invention, the diameter of the constituent fibers is 40 μm or less, preferably 28 μm or less, more preferably 20 μm or less, particularly preferably 15 μm or less, and the opening ratio is 30% or more, preferably 50
% Or more. With such a configuration, a mesh cloth excellent in various performances such as printing accuracy and filtration accuracy can be obtained. Generally, it has been difficult to obtain an aperture ratio of 50% or more.
%, Especially 55% or more, and even 60% or more. However, if the opening ratio is too large, misalignment and mesh opening diameter tend to be uneven, and dimensional stability and mechanical performance tend to be insufficient, so that the opening ratio is 75% or less, particularly 70%. It is preferable to set the following. The aperture ratio according to the present invention can be determined by the method described in Examples.

However, when ordinary fibers are used, a desired mesh cloth cannot be obtained. That is, if the fiber diameter of the constituent fibers is small, the strength of the fibers becomes small, the dimensional stability and mechanical performance of the mesh cloth become insufficient, and the opening diameter tends to become uneven. From the above, it is necessary that the main component of the fiber constituting the mesh cloth is a molten liquid crystalline polyester. By using such fibers, excellent dimensional stability and the like are exhibited even when the fiber diameter is reduced and the aperture ratio is increased. As long as the effects of the present invention are not impaired, components other than the molten liquid crystalline polyester may be contained in the monofilament. For example, polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyphenylene sulfide,
Polymers such as polyetheretherketone and fluororesin, and inorganic substances such as titanium oxide, silica and barium oxide,
Various additives such as an antioxidant, an ultraviolet absorber, and a light stabilizer may be included. From the viewpoint of the fiber performance of the monofilament, it is preferable that 70% by weight or more, preferably 80% by weight or more, and more preferably 90% by weight or more of the fiber constituent component is a molten liquid crystalline polyester.

[0008] The term "molten liquid crystalline (anisotropic)" as used in the present invention means to show optical liquid crystalline (anisotropic) in a molten phase. For example, it can be recognized by placing the sample on a hot stage, heating and heating the sample in a nitrogen atmosphere, and observing the transmitted light of the sample. The aromatic polyester used in the present invention is composed of a repeating structural unit such as an aromatic diol, an aromatic dicarboxylic acid, or an aromatic hydroxycarboxylic acid, and is preferably composed of a combination of the repeating structural units shown in the following Chemical Formulas 1 to 3. .

[0009]

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[0010]

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[0011]

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Particularly preferred is a polymer comprising a combination of repeating structural units shown in Chemical formula 3. Above all (A)
And a polymer in which the portion composed of the repeating constitutional units of (B) is 65% by weight or more is preferable, and in particular, the component of (B) is from 4 to
An aromatic polyester which is 45% by weight is preferred.

The melting point (MP) of the molten liquid crystalline polyester is preferably from 260 to 360 ° C., more preferably from 270 to 360 ° C.
350 ° C. The melting point referred to here is a differential scanning calorimetry (DSC: manufactured by Mettler, TA3000, for example).
Is the peak temperature of the main endothermic peak observed in (JIS)
K7121). Specifically, after taking 10 to 20 mg of a sample in a DSC device and sealing the sample in an aluminum pan, 100 cc / min of nitrogen was flowed as a carrier gas at 20 ° C.
The endothermic peak is measured when the temperature is raised at a rate of / minute. If a clear endothermic peak does not appear in the first run depending on the type of the polymer, the temperature is raised to a temperature 50 ° C. higher than the expected flow temperature at a rate of 50 ° C./min.
After completely melting for one minute, it is preferable to cool to 50 ° C. at a rate of 80 ° C./min, and then measure the endothermic peak at a rate of temperature rise of 20 ° C./min.

[0014] The mesh cloth may be composed of fibers mainly composed of the molten liquid crystalline polyester, but the constituent fibers need to be monofilaments. That is, when the constituent fiber is a multifilament or spun yarn, a mesh cloth excellent in various performances such as printing accuracy and filtration accuracy cannot be obtained because the fiber diameter and the opening diameter are likely to vary. . The mesh woven / knitted material may be constituted by such a monofilament, but is preferably a plain woven fabric from the viewpoint of the manufacturing process, the dimensional accuracy of the mesh cloth opening, and the like. As long as the effects of the present invention are not impaired, a mesh cloth may be formed by using fibers other than the monofilament in combination.However, from the viewpoint of efficiently obtaining the effects of the present invention, it is specified in the present invention. 50% by weight or more of the monofilament
It is preferable to use a mesh cloth having a weight percentage of at least 90% by weight.

[0015] In terms of various functions such as printing accuracy and filtration accuracy, the mesh cloth is more than 200 mesh, especially 25 mesh.
The mesh size is preferably 0 mesh or more, more preferably 300 mesh or more, and further preferably 350 mesh. By using such a mesh, high-precision printing, filtration, and the like can be performed. From the viewpoints of cost and productivity, it is preferable that the mesh size be 500 meshes or less.

The method for producing such a mesh cloth is not particularly limited, but a high-quality mesh cloth cannot be obtained by an ordinary method. That is, since the molten liquid crystalline polyester is highly oriented and crystallized only by spinning, it cannot be substantially stretched, so that there is a problem that it is difficult to obtain a small-diameter fiber. Even if it is used, it is difficult to produce a high-quality mesh cloth because it is easily fibril in a weaving process or the like. From the above, by removing the B component of the woven or knitted product containing the core-sheath type composite monofilament in which the core component is composed of the molten liquid crystalline polyester (A component) and the sheath component is composed of the easily soluble polymer (B component), It is preferable to adopt a method for producing a desired mesh cloth.

According to this method, fibrils are less likely to occur in the weaving step, etc., and by removing the B component, the diameter of the constituent fibers is reduced and the opening ratio of the mesh cloth is increased. Is a high-strength, high-modulus monofilament, so that a high-quality mesh cloth excellent in various properties can be obtained. In addition, even when the island component is a molten liquid crystalline polyester and the sea component is a sea-island structure fiber composed of a readily soluble polymer, the generation of fibrils during weaving or the like can be suppressed efficiently, The desired effect cannot be obtained because the removed fiber does not become a monofilament. The sea-island structure according to the present invention refers to a state in which tens to tens of thousands of islands are present in a sea component serving as a matrix in a fiber cross section.

As the component B constituting the sheath component, any component capable of forming a core-sheath type conjugate fiber with a molten liquid crystalline polymer and capable of being removed without substantially impairing the performance of the molten liquid crystalline polyester can be used. From the viewpoints of fibril resistance, spinnability and the like, a thermoplastic polymer is preferred. More specifically, a thermoplastic polymer that can be dissolved and decomposed by water (including hot water), alkali, acid or the like can be used. From the viewpoint that the processability and the performance of the component A are not easily impaired, those having a large difference in dissolution (decomposition) rate with the component A are preferable. Available B
As the component, for example, polylactic acid, thermoplastic water-soluble modified polyvinyl alcohol (for example, having an average degree of polymerization of 200
~ 500, ethylene unit of saponification degree 75 ~ 99%
Modified polyvinyl alcohol containing 20%), alkali easily soluble polyester and the like can be suitably used. Above all, it is preferable to use a modified polyester from the viewpoint of spinnability and the like.
More preferably, the alkali-soluble polyester which is almost completely dissolved (decomposed) within 60 minutes, particularly within 30 minutes, and further within 15 minutes when immersed at 0: 1.

Among them, polyesters containing the following structural units I to III are more preferably used because they are extremely excellent in alkali solubility (decomposability) and spinnability with a molten liquid crystalline polyester.

[0020]

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From the viewpoint of alkali solubility and spinnability, the structural unit I is composed of 0.5 to 1 of the total acid component constituting the polyester.
It is preferably 0 mol%, particularly preferably 1 to 7 mol%, and is a copolymerized polyester having a total content of the constituent units II and III of 2 to 50% by weight, particularly 5 to 30% by weight of the polyester. Is more preferred. A commercially available antioxidant (for example, Irganox 101 manufactured by Ciba-Geigy)
0, Cyanox 179 manufactured by American Cyanide
By adding 0), the heat resistance can be further improved.

Examples of the trivalent aromatic group (Ar) in the dicarboxylic acid unit I include a benzenetriyl group and a naphthalenetriyl group, and the metal atom M is sodium,
It is preferably an alkali metal atom such as potassium or lithium. Other carboxylic acid units constituting the copolymerized polyester include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, biphenyl dicarboxylic acid, aromatic dicarboxylic acids such as diphenyl ether dicarboxylic acid, β-
Examples thereof include hydroxyethoxy acid, P-oxybenzoic acid, aromatic hydroxycarboxylic acid, aliphatic carboxylic acid, carboxylic acid, and tricarboxylic acid. A plurality of these carboxylic acid units may be used. It is preferred that at least 70% by weight of all the acid components constituting the copolymerized polyester are aromatic dicarboxylic acid units, particularly terephthalic acid units.

R ¹ in the diol unit II has 1 carbon atom.
The alkylene group is preferably an ethylene group and / or a propylene group, particularly preferably an ethylene group from the viewpoint of alkali solubility. The average degree of polymerization m is 1
It needs to be 0 to 100, but more preferably 20 to 80. Of these, units derived from polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene / polyoxypropylene glycol, and the like are preferable. The copolymerized polyester preferably further has another diol unit, and an aliphatic diol, an alicyclic diol and the like are preferably exemplified. A unit derived from an alkylene glycol having 2 to 8 carbon atoms is preferred from the viewpoint of fiber-forming properties.

R ² in the side chain unit III is preferably an alkylene group having 1 to 4 carbon atoms.
Alternatively, a propylene group, particularly an ethylene group is preferred. R ³
A linear or branched alkyl group having 1 to 18 carbon atoms,
A cycloalkyl group having 3 to 18 carbon atoms and an aryl group having 6 to 18 carbon atoms are preferable. The degree of polymerization n is 10 to 100,
In particular, it is preferably from 20 to 80. Specifically, polyoxyethylene glycol-alkyl-glycidyl ether, polyoxyethylene glycol-alkyl-2,3
-Hydroxypropyl ether, polyoxyethylene glycol-phenyl-2,3-dihydroxypropyl ether, polyoxyethylene glycol-cyclohexyl glycidyl ether, polyoxyethylene glycol-cyclohexyl 2,3-dihydroxypropyl ether, and the like. A plurality of types may be used.

The component B includes other polymers, inorganic substances such as titanium oxide, kaolin, silica and barium oxide, antioxidants, ultraviolet absorbers, light stabilizers and the like as long as the effects of the present invention are not impaired. Various additives may be blended.
What is necessary is just to obtain a core-sheath type composite fiber using such A component and B component. The manufacturing method is not particularly limited, and a conventionally known method may be adopted. From the viewpoint of effectively obtaining the effects of the present invention, it is preferable to produce a single-core sheath-core composite fiber. The diameter of the core-sheath type composite fiber is not particularly limited, but from the viewpoint of the diameter of the core component, spinnability, cost, aperture ratio, etc., the diameter is 10 to 100.
μm, particularly preferably 15 to 50 μm, more preferably 18 to 40 μm. The core component ratio (weight ratio) in the composite fiber is preferably 0.1 to 0.9, more preferably 0.2 to 0.7 from the viewpoint of mechanical performance, fibril resistance, opening ratio and the like. Preferably, the components have a shape that approximates a circle. The diameter of the component A after the removal of the component B is 40 μm or less, preferably 28 μm or less, and more preferably 20 μm or less.
m, particularly preferably 15 μm or less, and preferably 10 μm or more from the viewpoint of weaving properties and the like. When the diameter of the component A is too small, the mechanical performance and the like become insufficient even if the component A is coated, and the weaving property and the like are liable to deteriorate.

The strength of the composite fiber is 10 g / d or more, the elastic modulus is 400 g / d or more, and the strength is particularly 12 g / d or more.
The elastic modulus is preferably 450 g / d or more. Since the mechanical performance of such a conjugate fiber is mainly determined by the component A, a mesh cloth having excellent dimensional stability and mechanical performance can be obtained by using such a conjugate fiber. B
The strength of the monofilament after component removal is 10g
/ D or more, elastic modulus 400 g / d or more, especially strength 12 g / d
As described above, the elastic modulus is preferably 450 g / d or more.

A desired mesh cloth can be obtained by producing a fabric using the core-sheath type composite fiber and then removing the B component. Since such a composite fiber has a core component that is easily fibrillated covered with a sheath component,
The generation of fibrils is effectively suppressed, and high-density weaving can be performed. At this time, an oil agent may be applied to the fiber if desired, and the number of fibers to be laid and the density of the woven fabric may be appropriately changed according to the core-sheath ratio of the fiber, the desired opening ratio, the mechanical performance of the fiber, and the like. The method for removing the component B is not particularly limited, but it is preferable to employ a method capable of removing (dissolving / decomposing) the component B without substantially impairing the performance of the component A.

For example, when the component B is the above-mentioned thermoplastic water-soluble modified polyvinyl alcohol, warm water (for example, 6
(0-100 ° C.), and in the case of an alkali-soluble polyester, for example, an alkaline aqueous solution may be used. Molten liquid crystalline polyester is, for example, about five times or more more excellent in alkali resistance than polyethylene terephthalate, which is a general-purpose polyester widely used in the past, so that alkali treatment does not substantially impair fiber performance. B component can be removed. More specifically, a weak alkali such as sodium carbonate, sodium silicate and sodium dihydrogen phosphate, and a strong alkali such as sodium hydroxide and potassium hydroxide can be used. Further, a decomposition accelerator or the like may be blended, or a surfactant may be added to enhance the permeability to the fiber. For example, a 4% aqueous sodium hydroxide solution at 80 ° C. can be suitably used.

The method of applying an alkaline solution or the like to the mesh cloth is not particularly limited, but a method of immersing the mesh cloth in a treatment solution (including a method of suspending the mesh cloth in an alkaline bath and continuously passing it through the treatment bath) is used. It can be suitably used. There is no need to completely remove the B component,
As long as the effects of the present invention are not impaired, the B component may remain on the mesh cloth, but from the viewpoint of more efficiently obtaining the effects of the present invention, 95% or more of the B component is removed. Is preferred.

Although the mesh cloth obtained by such a method has excellent mechanical performance, the mechanical performance can be further improved by further heat treatment. It is also possible to weave the heat-treated fiber, but in this case, since the fiber becomes rigid, the workability is reduced, and the fibril is more likely to be generated. Is preferred. Although heat treatment may be performed before the removal of the B component, it is more efficient to perform the heat treatment after the removal of the B component, which is also preferable in terms of fiber performance. When the mesh cloth is used for a screen gauze or a filter, the heat treatment is performed after the mesh cloth from which the B component has been removed is spread on a frame such as a printing screen frame. Can be further increased, so that a more preferable effect can be obtained.

The heat treatment may be performed in an active atmosphere and / or an inert atmosphere, and may be either a relaxation heat treatment or a tension heat treatment. B to prevent sticking
It is preferably carried out at a temperature not higher than the melting point of the component. When the melting point of the component B is defined as MPb, (MPb-80 ° C.) to (MPb
C.). The melting point of the component B may be exceeded as long as no sticking occurs. The heat treatment atmosphere is preferably a low-humidity gas having a dew point of -80 ° C or less, and the heat treatment is preferably performed in a temperature pattern in which the temperature is gradually increased from the melting point of the core component of -40 ° C or less to the melting point of the sheath component polymer or less. Processing time may be from a few minutes to a few tens of hours

The heat is supplied in the heat treatment by a method using a medium such as a gas, a method using radiation from a heating plate or an infrared heater, a method using a heat roller, a heat plate or the like, or a method using a high frequency or the like. A heating method or the like can be used. Heat treatment shape: scallop shape, toe shape (for example, put on a metal net etc.)
Or it is also possible to process continuously between rollers. When performing a tension heat treatment, the melting point of the core component is -80 ° C.
It is preferable to apply a tension of 1 to 10% of the cutting strength at the following temperature, and this treatment can further improve various performances, particularly elastic modulus. Needless to say, other treatments other than the heat treatment, such as plasma treatment and water repellency treatment, may be further performed as desired.

The mesh cloth of the present invention can be used for various purposes because it is composed of fine fibers, has a high aperture ratio, and is excellent in mechanical performance. For example, it can be suitably used as a filter, an electromagnetic wave shield, a screen gauze, a printed wiring board and the like. For example, when the mesh cloth of the present invention is used for a filter, it is possible to perform high-precision filtration or trapping of fine particles because the opening diameter can be reduced, and the opening ratio is large and the constituent fibers are small in diameter. A remarkable effect that the accuracy is high and clogging is hardly generated can be obtained. When the mesh cloth of the present invention is used for a printed wiring board, a dense and highly accurate conductive pattern can be disregarded by filling a desired opening of the mesh cloth with a conductive substance.

As described above, the mesh cloth of the present invention can be used for various applications and has excellent performance, but a more remarkable effect can be obtained when it is used as a screen gauze. More specifically, it can be suitably used for pattern printing, solid printing, character printing, nameplate printing, color printing, etc., and is excellent in printing of edging resist ink, plating resist ink, ceramic paste, copper and silver paste, etc. Performance. That is,
Such a screen gauze is dense, has a large aperture ratio, is unlikely to generate fibrils and the like, and is made of a monofilament having excellent mechanical performance, so that a fine and highly accurate print pattern can be formed. In addition, clear printing can be stably performed. More specifically, the fiber width and the line spacing are 100 μm or less, particularly 10 μm.
Printing of up to 80 μm is possible, and a large aperture ratio results in a high-definition finish. In addition, it can contribute to the weight reduction, thinning, and significant cost reduction of substrates in the production of fine pattern substrates for electronic devices.

[0035]

Next, the present invention will be described in more detail with reference to specific examples. It should be noted that the present invention is not limited to the examples described below.

[Melt viscosity (MV) poise] Measured using a Capillograph 1B manufactured by Toyo Seiki Co., Ltd. under the conditions of 300 ° C. and shear rate r = 1000 sec ⁻¹ . [Fiber diameter μm] A photograph of the fiber side surface magnified 1000 times was taken with a scanning electron microscope, and the fiber diameter was measured at any 10 points. The arithmetic mean was defined as the fiber diameter.

[Aperture ratio%] A photograph at a magnification of about 200 is taken by a scanning electron microscope, and is obtained by the following equation.
In addition, the diameter of at least 5 warp yarns and weft yarns was measured,
The average values are D1 and D2, respectively, and the distance between adjacent warp yarns and the distance between adjacent weft yarns are measured at five or more locations, and the average values are L1 and L2, respectively. Opening ratio (%) = (L1 / L2 / L1 / D2 / L2 / D1)
+ D1 · D2) / L1 · L2 × 100

REFERENCE EXAMPLE 1 As a polymer A, a molten liquid crystalline polyester containing 73/27 mol% of the structural units (A) and (B) represented by Chemical Formula 3 (melting point: 280 ° C., melt viscosity: 4)
10poise, ηinh = 4.20 dl / g) and B
As a polymer, dimethyl 5-sodium sulfoisophthalate (I) is 2.5 mol% of the total acid component constituting the copolymerized polyester, polyoxyethylene glycol (II) having a molecular weight of 2,000, and polyoxyethylene represented by the following formula (5). A copolyester (intrinsic viscosity: 0.6 dl / g) in which components derived from glycidyl ether (III) accounted for 10% by weight of the total copolyester, and the balance was terephthalic acid and ethylene glycol, was used. The copolymer polyester contains 5% by weight of an antioxidant (CYANOX 1790 manufactured by American Cyamid Co.) based on the total amount of the polyoxyethylene glycol and the polyoxyethylene glycidyl ether. Nozzle diameter 0.15mmφ using such polymer
Was spun at 308 ° C. by using a die having a core component of 50% by weight and a core-sheath type composite fiber having a diameter of 24.5 μm.

[0039]

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Reference Example 2 A core / sheath composite fiber having a diameter of 24.5 μm was produced in the same manner as in Reference Example 1 except that the core component ratio was changed to 30% by weight.

Example 1 A plain weave of 330 mesh was woven using the core-sheath composite fiber obtained in Reference Example 1, but the weavability was good and a woven fabric could be produced without any particular trouble. Next, when this woven fabric was immersed in a 4% aqueous sodium hydroxide solution at 80 ° C. for 15 minutes, the B component could be completely removed without substantially impairing the performance of the A component (weight loss rate: 50). .1% by weight). Next, the mesh cloth obtained by removing the component B was placed in a drier at 265 ° C. in a nitrogen atmosphere and subjected to a heat treatment for 8 hours. By performing such heat treatment, the mechanical performance of the constituent fibers was significantly improved, and a mesh cloth excellent in mechanical performance and dimensional stability was obtained. The diameter of the monofilament constituting the obtained mesh cloth is 17 μm for the warp and 18 μm for the weft, and the opening width of the mesh is 77 μm between the warps and 7 μm between the wefts.
6 μm, and the aperture ratio was 59.5%.

Such a mesh cloth was composed of fine fibers and had a large aperture ratio, and had high mechanical performance and high quality. In general, when weaving using a molten liquid crystalline polyester fiber, fibrils are generated and the quality is impaired.However, since fibrils are not substantially generated in the mesh cloth obtained by such a method, and since it is composed of monofilaments, The dispersion of the wire diameter and the opening diameter was small and the performance was extremely high. Therefore, such a mesh cloth is suitable as a filter or the like, and particularly suitable as a screen gauze since a dense and precise print pattern can be formed.

Example 2 A 380 mesh plain weave was woven using the core-sheath type composite fiber obtained in Reference Example 2,
The B component was removed in the same manner as in Example 1 and heat treatment was performed. The diameter of the monofilaments constituting the obtained mesh cloth was 13 μm in warp and 14 μm in weft, the opening width of the mesh was 66 μm between warps, 67 μm between wefts, and the opening ratio was 63.5%.

The mesh cloth was made of fine fibers and had an extremely large aperture ratio, and had high mechanical performance and high quality. In general, when weaving using a molten liquid crystalline polyester fiber, fibrils are generated and the quality is impaired.However, since fibrils are not substantially generated in the mesh cloth obtained by such a method, and since it is composed of monofilaments, The dispersion of the wire diameter and the opening diameter was small and the performance was extremely high. Therefore, such a mesh cloth is suitable as a filter or the like, and particularly suitable as a screen gauze since a dense and precise print pattern can be formed. Although it is difficult to obtain a screen gauze having the above-described wire diameter and aperture ratio using a fine stainless wire, an extremely high-performance screen gauze was obtained according to this example.

Comparative Example 1 A mesh cloth was produced in the same manner as in Example 1 except that the component B was not removed. The diameters of the monofilaments constituting the obtained mesh cloth are 24.5 μm of warp and 24.5 μm of weft, the opening width of the mesh is 52.5 μm between warps, 51.5 μm between wefts, and the opening ratio is 28. 0.0%. Since such a mesh cloth has a small aperture ratio and a large portion where fibers are present, various functions such as printing accuracy and filter accuracy were inferior to those of Examples 1 and 2. For example, when used as a filter, the fibrous portion itself does not exhibit a filtering ability, so that the filtration accuracy and the accuracy of capturing fine particles are reduced, and clogging is liable to occur. However, since the fiber existing portion does not transmit the ink, it is difficult to perform dense and precise printing, and the ink removability and the like are apt to decrease, so that the desired effect cannot be obtained.

Claims (7)

[Claims] 1. A woven or knitted fabric composed of a monofilament made of a molten liquid crystalline polyester, wherein the monofilament has a diameter of 40 μm or less and an aperture ratio of 30.
Mesh cloth that is ~ 75%. 2. A woven or knitted fabric containing a core-sheath composite monofilament having a core component composed of a molten liquid crystalline polyester (component A) and a sheath component composed of an easily soluble polymer (component B). Mesh cloth. 3. The mesh cloth according to claim 1, wherein the aperture ratio is 50% or more. 4. The mesh cloth according to claim 1, wherein the diameter of the monofilament is 25 μm or less. 5. A screen gauze comprising the mesh cloth according to claim 1. 6. A mesh cloth for removing a B component of a woven or knitted fabric containing a core-sheath type composite monofilament having a core component composed of a molten liquid crystalline polyester (component A) and a sheath component composed of an easily soluble polymer (component B). Production method. 7. A screen gauze for removing a B component of a woven or knitted fabric containing a core-sheath type composite monofilament whose core component is composed of a molten liquid crystalline polyester (A component) and whose sheath component is an easily soluble polymer (B component). Production method.