JPH11200214A - Nonwoven fabric for washing blanket for printing machine, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nonwoven fabric for brankets for printing machines, showing no damage or notable elongation while in washing service, well holding a washing solution, suffering no separation of the constituent fibers, and improved in function of wiping out ink stains. SOLUTION: This nonwoven fabric is mainly composed of three-dimensionally entwining heat-fusible type synthetic fibers and very fine acrylic fibers having as aspect ratio of 700 to 3000 and fiber diameter of 8.0 μm or less, wherein the heat-fusible type synthetic fibers are partly fused with each other or with the very fine acrylic fibers. It is discharge-treated on one or both sides, and shows a water and oil absorbing rate of 10 sec or less, determined by the dropping method (JIS L 1907), tensile strength of 15 N/cm or more when it is dry or wet with water or oil, and elongation of 3.0% or less at a load of 5 N/cm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric for cleaning a printing press blanket for use in an automatic blanket cleaning device for a printing press, and a method for producing the same. The present invention relates to a nonwoven fabric for cleaning a printing press blanket, which has a small amount of water, has excellent cleaning liquid wettability, and has improved wiping properties, and a method for producing the same.

[0002]

2. Description of the Related Art An offset printing machine is a device for transferring ink to a blanket and then transferring the ink to a printing target for printing. When the blanket becomes dirty and printing becomes unclear, or when changing or restarting, it is necessary to clean the blanket to remove paper dust and ink. In the past, these cleanings were directly wiped off with a rag or a non-woven cloth held in a hand, which was not only time-consuming or spilled, but also involved the danger of being caught in because the rotating body was wiped off.

[0003] In recent years, automatic blanket cleaning systems have been introduced and people have been freed from wiping operations. A nonwoven fabric is generally used as a base fabric for blanket cleaning used in an automatic washing machine. Many automatic washing machines wash blankets while applying a washing liquid to the nonwoven fabric.
In this case, the printing press blanket cleaning nonwoven fabric needs to hold the cleaning liquid and wipe off the paper powder and ink attached to the blanket.

[0004] The main components of the cleaning liquid are water and an organic solvent.
Water is important for wiping paper powder, and organic solvent is important for wiping ink. Therefore, the nonwoven fabric for cleaning a printing press blanket is required to have sufficient strength for wiping, even in a state of being wetted with water and oil.

[0005] Spunbonded nonwoven fabrics, heat-sealed nonwoven fabrics, and water jet nonwoven fabrics are used as nonwoven fabrics for printing press blanket cleaning. Water jet nonwoven fabrics are generally used for offset printing presses because of their wiping properties and low lint properties. Widely used.

As a water jet nonwoven fabric, a nonwoven fabric obtained by laminating a dry web mainly composed of organic synthetic fibers and a sheet obtained by wet-making vegetable cellulose fibers and three-dimensionally entangled, and a sheet prepared by mixing organic synthetic fibers and vegetable cellulose are used. Dimensionally entangled nonwoven fabrics and the like are widely used as nonwoven fabrics for cleaning blankets in printing machines.

[0007] Although wood pulp has a certain wiping property, pulp may fall off during wiping or paper powder may fall off at the time of entanglement. While print finish is required, there has been a problem that the surface properties of printed matter are reduced. In the case of beating with a high-speed disintegrator or beater for the purpose of fibrillation, fine pulp fragments are generated, the pulp falls off at the time of entanglement, the yield decreases, and the pulp falls off so that it is difficult to see it when wiping. However, there is a possibility that it may be a problem for printed matter applications. There is also a blend of low-melting heat-fusible synthetic fibers that suppresses the dropping of wood pulp by the adhesive force of the heat-fusible synthetic fibers. There was a problem. In addition, there was a problem that pulp dropped off during the manufacturing process.

[0008] In particular, in an offset printing press for newspapers, the frequency of use of an automatic washing machine increases with the speeding up of printing equipment, and if pulp falls off on the blanket surface, it has a great effect on high-grade printed materials.

[0009] Further, when a blanket of a high-speed offset printing press for newspapers is continuously wiped off with a blanket for cleaning a printing press blanket, unevenness and unevenness in wiping due to elongation of the blanket for cleaning the printing press blanket have been observed. . For this reason, printing machine blanket-cleaning nonwoven fabrics have been required to have higher tensile strength and lower elongation under a constant load.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended to suppress the falling off of fibers at the time of manufacturing and washing, to have a high tensile strength and to suppress the elongation at a constant load. An object of the present invention is to provide a nonwoven fabric for cleaning a printing press blanket, which is excellent in liquid retaining property of a cleaning liquid and has improved wiping property during cleaning, and a method for producing the same.

[0011]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have invented a nonwoven fabric for cleaning a printing press blanket and a method for producing the same according to the present invention.

The nonwoven fabric for cleaning a printing press blanket according to the present invention has an aspect ratio of 700 to 300 that of a heat-fusible synthetic fiber.
0, contains ultra-fine acrylic fibers having a fiber diameter of 8.0 μm or less, these fibers are uniformly mixed and three-dimensionally entangled with each other, and at least a part of the heat-fusible synthetic fibers is And after adhering to a fine acrylic fiber, at least one surface is subjected to an electric discharge machining treatment, and is subjected to JIS L1907.
Water absorption rate measured by the dropping method and oil absorption rate measured using kerosene by a method based on the dropping method are all 10
Seconds or less, and the tensile strength is 15 N / cm or more in the vertical direction when dry, wet, or oil wet, and the elongation at 5 N / cm load in the vertical direction is 3.0.
%.

[0013] Preferably, it contains one or more vegetable cellulose fibers or hydrophilic synthetic fibers.

The vegetable cellulose fibers preferably have a weight average fiber length of 1.5 mm or more.

The hydrophilic synthetic fiber preferably has an aspect ratio of 500 or more.

The method for producing a nonwoven fabric for cleaning a printing press blanket according to the present invention is characterized in that an aspect ratio of the synthetic fiber is 700.
-3000, ultra-fine acrylic fiber having a fiber diameter of 8.0 μm or less is uniformly dispersed in water, made into a web by a wet papermaking method, loaded on a porous support, and jetted with a high-pressure columnar water stream to produce a fiber. Are three-dimensionally entangled, water is removed, the mixture is treated at a temperature higher than the melting point of the heat-fusible synthetic fiber, and then at least one surface is subjected to electric discharge machining.

Preferably, it contains at least one of vegetable cellulose fibers and hydrophilic synthetic fibers.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The nonwoven fabric for cleaning a printing press blanket of the present invention is a three-dimensionally entangled nonwoven fabric made of a specific heat-fusible synthetic fiber and an ultrafine acrylic fiber, and is heat-bonded.
It is subjected to electrical discharge machining, has excellent water absorbency and oil absorbency, has good compatibility with cleaning liquids, has high strength and low elongation, and has excellent wiping properties.

In the present invention, the specifications in JIS L1907 stipulate a method for testing the water absorption of textile products. "Water absorption" is represented by any of water absorption rate, water absorption rate, maximum water absorption rate, and water absorption at the time of the maximum water absorption rate. In the present invention, the water absorption rate is specified by the water absorption rate. Further, the water absorption rate can be classified into a dropping method, a birec method, and a sedimentation method, and among them, the dropping method is applied.

The dropping method is a method in which a test piece is held in a test piece holding frame such as a metal ring, and one drop of water is dropped on the surface of the test piece from a fixed height of a burette with a stopcock. Is the time from when the surface of the test piece reaches the surface of the test piece until the water droplet no longer undergoes special reflection, which is indicated as the water absorption rate (second). Here, "no special reflection" means that the specular reflection disappears as the test piece absorbs water droplets, and only wetness remains.

With respect to the nonwoven fabric for cleaning a printing press blanket using the automatic blanket cleaning device of the present invention, the water absorption rate of the nonwoven fabric was measured according to the above JIS L1907.
And the oil absorption rate is measured in accordance with the dropping method by using kerosene instead of water.

The smudge of the blanket is mainly caused by ink containing a vehicle and a pigment, and paper dust. The ink components include, for example, linseed oil, stand oil, castor oil, tung oil, and the like, and the oil-based cleaning liquid generally includes kerosene, light oil, gasoline, trichlene, and methyl chloroform. Is also commonly used.
When cleaning a blanket, oil-based and aqueous cleaning methods such as cleaning with an oil-based cleaning liquid having an affinity for a vehicle of an ink component with respect to ink stains, and cleaning using an aqueous cleaning liquid for cleaning these and cleaning of paper dust, etc. Requires two washes. To this end, it is essential that the nonwoven fabric for cleaning a printing press blanket has both oiliness and aqueous properties. In particular, since the latter cleaning using the aqueous cleaning liquid ultimately affects the cleaning state of the blanket, the hydrophilicity of the nonwoven fabric for cleaning a printing press blanket is indispensable. The hydrophilicity of the nonwoven fabric for cleaning a printing press blanket is nothing less than the water absorption rate of the nonwoven fabric.

In the present invention, the water absorption speed and the oil absorption speed of the nonwoven fabric for cleaning a printing press blanket are both preferably 10 seconds or less. When it is within the range, an excellent cleaning effect can be exhibited. Water absorption speed and oil absorption speed are 1
If the time exceeds 0 seconds, the cleaning liquid is not sufficiently retained, and the effect of cleaning lipophilic components such as ink cannot be sufficiently exhibited. In addition, there is also a problem that the cleaning liquid that cannot be completely retained drips from the nonwoven fabric and contaminates the blanket and printed matter.

Further, with the non-woven fabric for cleaning a printing press blanket, a high tension is applied to the non-woven fabric even at the time of washing with the speeding up of the printing equipment, and the non-woven fabric is broken or stretched. And bias will occur. Therefore, the tensile strength is 15N not only when dry but also when wet and oil.
/ Cm or more. In addition, the elongation should be suppressed, and the elongation under a load of 5 N / cm is 3.0 as a whole.
% Is preferable. If so,
For the first time, the nonwoven fabric can exhibit an excellent cleaning effect over the entire width of the blanket.

The measurement of the tensile strength of the nonwoven fabric for cleaning a printing press blanket during drying according to the present invention is performed according to JIS L10.
The tensile strength at the time of wet and oil wetness is measured according to the strength measurement method after immersing the nonwoven fabric in water or kerosene. The elongation under a constant load is measured by measuring the elongation when a load of 5 N / cm is applied in measuring the tensile strength.

The aspect ratio used in the present invention is 700 to 700.
An ultrafine acrylic fiber having a diameter of 3000 and a fiber diameter of 8.0 μm or less will be described. Acrylic fiber is a fiber containing 50% or more of polyacrylonitrile. Acrylic fibers are rich in water absorbency and oil absorbency, and are excellent in the ability to clean both aqueous and oily stains. The aspect ratio of the acrylic fiber is preferably in the range of 700 to 3000. here,
If it is less than 700, the entanglement of the fibers is weak, and a strong sheet strength cannot be obtained. On the other hand, if the molecular weight is larger than 3000, not only the dispersion of the fibers is deteriorated, but also a high-pressure entanglement is required to obtain a strong entanglement for preventing the fibers from coming off from the surface. In addition, plant cellulose fibers and hydrophilic synthetic fibers which will be described later are not preferred because they fall off during the entanglement step. The fiber diameter of the acrylic fiber is preferably 8.0 μm or less.

The use of fibers having such a fiber diameter not only improves the hydrophilicity and lipophilicity, but also has the advantage of preventing other fibers from falling off. The ultrafine acrylic fiber has a small fiber diameter and therefore has a large fiber surface area, and is improved in hydrophilicity and lipophilicity as compared with a mixture of the same weight% as the normal diameter acrylic fiber. Further, it is considered that when the ultrafine acrylic fibers uniformly dispersed in the web are mixed with other fibers, the fibers are easily entangled with other fibers, and the falling off is suppressed. When it is larger than 8.0 μm, not only the liquid absorbability and the wiping property are reduced, but also the detachment of the heat-fusible synthetic fiber, the vegetable cellulose fiber and the hydrophilic synthetic fiber is increased.

The heat-fusible synthetic fiber used in the present invention refers to a fiber that adheres to acrylic fibers and other constituent fibers by heat treatment, and a heat-fusible fiber made of a thermoplastic polymer or the like that melts by heat. Is exemplified. The heat-fusible synthetic fibers are polyethylene, polypropylene, olefin-based fibers whose melting points have been lowered by copolymerization, polyester-based fibers whose melting points have been lowered by methods such as copolymerization and undrawing, and polyamide-based fibers such as nylon. A fiber is exemplified. These fibers are preferably a single component or a composite fiber composed of two or more components. As the composite fiber, a core-sheath fiber in which a high-melting core component is coated with a low-melting component surface is particularly preferable.

The fineness of the heat-fusible synthetic fiber is preferably in the range of 0.5 to 6 denier, more preferably 0.5 to 6 denier.
3 denier. When the denier is less than 0.5 denier, not only the nonwoven fabric for cleaning a printing press blanket becomes dense, but also the surface area of the heat-fusible synthetic fiber occupying in the sheet becomes large, and the liquid absorbing property is unfavorably reduced.

If the denier exceeds 3 denier, the number of heat-fusible synthetic fibers in the nonwoven fabric for cleaning a printing press blanket decreases, and the bonding portion with other fibers decreases.
Adhesive strength decreases. In addition, even with the same fiber length, bending becomes difficult and entanglement becomes weak, which is not preferable.

The blending amount of the heat-fusible synthetic fibers is preferably at least 10% by weight of the nonwoven fabric for cleaning a printing press blanket. 1
If it is less than 0% by weight, the adhesive strength is insufficient, and it is difficult to fix other fibers. As a result, the mechanical properties of the water-permeable sheet are reduced, fluff is generated, and the dimensional stability is reduced.

The present invention also provides a nonwoven fabric for cleaning a printing press blanket, which further improves water absorbability and is excellent in wiping properties by blending one or more vegetable cellulose fibers or hydrophilic synthetic fibers. it can.

The vegetable cellulose fibers used in the present invention are classified into woody cellulose fibers and herbaceous cellulose fibers. Woody cellulosic cellulose fibers include softwood or hardwood timber fibers such as kraft pulp, sulfite pulp, thermomechanical pulp, mechanical pulp, etc., vascular fibers such as bamboo, pulp, mulberry Pulp made of bast fibers such as mulberry, mitsumata, and goose. The herbaceous cellulose fibers include cotton fibers (lint, linter), hemp fibers (flax, ramie, manila hemp) or pulp of these, bagasse, esparto, kenaf and the like. It also includes pulp obtained from straw, waste paper, broke, and the like. Further, those chemically modified with these plant cellulosic fibers can also be used. One or more of these pulp can be appropriately selected and used.

Among these plant cellulosic fibers, the weight average fiber length is 1.5 mm or more and the number average fiber length is 0.1 mm.
It is preferable to select and use one of 7 mm or more.
The fiber length used in the present invention is JAPAN TAPPI paper pulp test method No. 52 shows the weight average fiber length and the number average fiber length measured by the method described in JP-A-52-89.

When the weight average fiber length is shorter than 1.5 mm,
Not only is the entanglement between the plant cellulosic fibers and other fibers insufficient, but the fibers also fall off from the product,
There is a problem of sticking to a blanket, which is not preferable.

If the number average fiber length is shorter than 0.7 mm, short fibers, ie, fiber fragments, are large, so that the fibers fall off from the product and become large and adhere to the blanket. It grows bigger and I can't get what I want. Therefore, there is a problem that the liquid absorption is insufficient, which is not preferable. In addition, when the pulp that has fallen off during the entanglement process adheres to the wire, making it difficult for the pulp to separate from the wire, the pulp flows out during drainage, the amount of suspended solids increases, or when water is recycled and used, The nozzle may be clogged by fine fiber fragments that cannot be processed.

The hydrophilic synthetic fibers used in the present invention include regenerated cellulosic fibers such as viscose rayon, copper ammonium rayon, polynosic rayon, and lyocell;
Regenerated fibers obtained by spinning a solution of collagen, alginic acid, chitin or the like are preferred. The polymer constituting these fibers can be used in the form of a homopolymer, a modified polymer, a blend, a copolymer, or the like. Of course,
A composite fiber made of a plurality of these materials may be used.

From among these hydrophilic synthetic fibers, those having an aspect ratio of 500 or more are preferably used. If the aspect ratio is less than 500, entanglement between fibers is weak, and high tensile strength cannot be obtained, which is not preferable. If the entanglement is to be carried out strongly, it is necessary to increase the entanglement pressure. As a result, not only is it difficult to peel off from the wire, but also other fibers flow out into the drainage water, which leads to a decrease in water absorption. However, if the aspect ratio is 5
It is not limited that fibers of less than 00 are combined or used within a range that does not hinder the performance of the nonwoven fabric for cleaning a printing press blanket.

Next, the material and shape of the synthetic fiber used in the present invention will be described. The heat-fusible synthetic fibers, acrylic fibers, and hydrophilic synthetic fibers used in the present invention may be composite fibers made of a plurality of these materials. Further, it may be a branched one or a pulp one. Also, the fiber cross-section may be a so-called irregular cross-section fiber such as T-type, Y-type, U-type, star-type, dog-bone-type or the like which is not circular or elliptical, or may have a dividing property. A plurality of fibers having different fiber diameters and different fiber lengths may be appropriately mixed according to the purpose.

The synthetic fiber in the present invention not only imparts strength to the nonwoven fabric for cleaning a printing press blanket of the present invention but also prevents the falling off of vegetable cellulose fibers by the strong entanglement of the synthetic fibers. Plays a role of efficiently wiping and holding the ink adhered to the surface.

Particularly, when the aspect ratio is 700 to 3000,
Nonwoven fabrics for cleaning printing presses containing ultrafine acrylic fibers having a fiber diameter of 8.0 μm or less are excellent in hydrophilicity and lipophilicity, and not only are the ultrafine acrylic fibers intertwined with each other, but also with other synthetic fibers and vegetable cellulose fibers. Entangled tightly. Thereby, the printing press blanket cleaning nonwoven fabric of the present invention efficiently wipes and retains the ink or cleaning liquid attached to the blanket, not only imparts strength during drying, but also suppresses elongation under a constant load, It plays a role in preventing the falling off of the cellulose fibers.

Further, the heat-fusible synthetic fiber is fused with the heat-fusible synthetic fibers, vegetable cellulose fibers and hydrophilic synthetic fibers at least in part, so that the entanglement between the fibers and the synergistic effect of the plant fibers enable the plant heat to be produced. Cellulose fibers can be prevented from falling off. In addition, it is possible to prevent the cleaning liquid from being applied or the blanket from being washed, and the nonwoven fabric for cleaning the printing press blanket from being wetted with the cleaning liquid or ink and the sheet strength from being reduced.

The fiber diameter of the synthetic fiber used in the present invention is 5 to 5.
30 μm is preferable, and more preferably, 7 to 25 μm
It is. If the thickness is smaller than 5 μm, the sheet becomes dense, and the liquid retaining properties of the ink and the cleaning liquid are undesirably reduced. 30μ
If it is larger than m, the detachment of the vegetable cellulose fibers at the time of confounding becomes large, which is not preferable.

However, fibers having a size of less than 5 μm or fibers having a size of more than 30 μm may be mixed with fibers having a size of 5 to 30 μm.
The use of the nonwoven fabric for cleaning a printing press blanket is not limited to the range that does not impair the performance.

The fiber length of the synthetic fiber may be a fiber length at which the fibers are entangled, and the degree of entanglement depends on the ratio of the fiber length to the fiber diameter and the aspect ratio (fiber length / fiber diameter). You. Specifically, the aspect ratio is 500
~ 3000 are preferred. If it is less than 500, the fibers are hardly bent, and the entanglement between the fibers is weak, which is not preferable. If the entanglement is attempted to be performed strongly, it is necessary to increase the entanglement pressure, which is not preferable because the dropout of the vegetable cellulose fibers increases.

On the other hand, if the aspect ratio is larger than 3000, it is difficult to obtain a good web in the papermaking process, which is not preferable. However, fibers having an aspect ratio of less than 500 or more than 3000 may be mixed with fibers of 500 to 3000 or used in a range that does not impair the performance of the nonwoven fabric for cleaning a printing press blanket.

Next, a state where at least a part of the synthetic fiber is adhered will be described. The term “adhesion” as used herein refers to a state in which some fibers are melted and bonded to other fibers, or a state in which some of the fibers are melted and bonded to other fibers. By bonding at least a part of the entangled synthetic fibers, the strength is of course improved,
Furthermore, it plays a role in preventing the detachment of vegetable cellulose fibers and other synthetic fibers during washing. Further, it is possible to prevent the nonwoven fabric for cleaning of a printing press blanket from being stretched in a state where the cleaning liquid is contained, and it is also effective to maintain a good wiping property.

Further, at least one surface of the nonwoven fabric for cleaning a printing press blanket is subjected to electric discharge machining. As described above, the heat-fusible synthetic fiber is melted by heat treatment, and the cross-sectional deformation or at least a part of the heat-fusible synthetic fiber adheres to the microfine acrylic fiber, the vegetable cellulose fiber, or the hydrophilic synthetic fiber. The surface area of the fiber increases. Therefore, the water absorption decreases due to the melt plasticization of the heat-fusible synthetic fiber surface. In addition, the area of the heat-fusible synthetic fiber covering the surface of the fiber that contributes to other water absorption increases, and the water absorption decreases. Therefore, by performing the electric discharge machining after the heat treatment, the fiber surface can be made water-absorbing without impairing the mechanical properties and dimensional stability.

The electric discharge machining treatment is a treatment in which a discharge phenomenon generated by a high voltage when the web passes between the electrode and the rotating roll modifies the web surface and attaches a hydrophilic group. Examples of the electric discharge machining device include a corona discharge machining device, a vacuum plasma machining device, an atmospheric pressure plasma machining device, and the like. Of these, the corona discharge machining device is preferable because of its simple facility and high machining speed.

Next, a process for producing the nonwoven fabric for cleaning a printing press blanket of the present invention will be described. There is no particular limitation on the method of producing the web before entanglement. The obtained web may be entangled in a single layer, or two or more layers may be stacked and entangled. However, it is preferable to use a web by a wet papermaking method from the viewpoint that it is preferable to unnecessarily increase the basis weight of the nonwoven fabric for cleaning a printing press blanket and to produce a uniform web so as not to increase the thickness. When a web obtained by a method such as a dry method is used, not only is it difficult to efficiently produce a uniform nonwoven fabric for cleaning a printing press blanket, but the fiber diameter used in the present invention is 8.0 μm. It is also difficult to use the following ultrafine acrylic fibers.

Here, a web production method by a wet method will be described. First, heat-fusible synthetic fibers, microfine acrylic fibers, vegetable cellulose fibers or hydrophilic synthetic fibers are uniformly introduced into water, mixed with a rotary device such as a pulper, and defibrated and dispersed. A suspension having a concentration of about 0.1 to 3% is prepared. Next, the suspension is used to form a web using a paper machine having at least one wire such as a long net, a short net, and a circular net, thereby obtaining a web.

When the aspect ratio of the synthetic fibers is large, special attention must be paid to the method of preventing the fibers from being entangled at the time of defibration and dispersion. It is easier to prevent the synthetic cellulose fibers from entering and the synthetic fibers from tangling, and to obtain a uniform web with better texture than in the case where the synthetic fibers are defibrated and dispersed alone.

Next, the web thus obtained is
It is placed on a porous support such as a 60-150 mesh wire, and a high-pressure columnar water stream is jetted to entangle the fibers to obtain an entangled web.

In order to carry out the confounding strongly, the high pressure columnar water flow should have a nozzle diameter of 10 to 500 μm.
Is preferable, and the interval between the nozzles is 10 to 1500 μm.
Is preferred.

These nozzles need to have a range which can be processed at least once or more by a water flow across the width of the conveyed web. In consideration of the type of web, the basis weight, the processing speed, and the water pressure, the number of entanglements and the number of nozzles can be changed and used as long as sufficient entanglement can be obtained.

The water pressure is preferably used in the range of 10 to 250 kg / cm ² . More preferably, 10 to 100K
g / cm ² . The processing speed is preferably used in the range of 3 to 200 m / min.

The entangled web thus obtained is dried after removing excess moisture by a method such as suction or wet pressing. As a device for drying, a cylinder dryer, an air dryer, an air through dryer, a suction dryer, and the like are preferable, and the device can be used at a temperature at which water is substantially completely removed.

Next, simultaneously with or after drying, at least a portion of the heat-fusible synthetic fibers are bonded to each other, the hydrophilic synthetic fibers, and the vegetable cellulose fibers. Examples of the method of bonding include treating at a temperature equal to or higher than the melting point of the heat-fusible synthetic fiber, melting at least a part of the heat-fusible synthetic fiber, and cooling the fiber so as to be in an adhesive state with other fibers. . The following method is exemplified as a method of treating at a temperature higher than the melting point of the heat-fusible synthetic fiber. Specifically, using an apparatus such as an air-through dryer, an air dryer, and an infrared dryer, a method of bringing the atmosphere of the dried entangled web to the melting point or higher, contacting with a cylinder dryer, or processing under a nip of a calendar, Alternatively, one of the preferred methods is to use an embossing roll and a flat roll in combination to apply point bonding. Further, these methods can be used in combination.

The treatment temperature may be any temperature higher than the melting point of the heat-fusible synthetic fiber, but a temperature of 20 ° C. or more is a preferable temperature for further strengthening the bonding.

Next, at least one surface is subjected to electric discharge machining. Total processing energy per side is 0.05 ~
Gives a work load of 2.0 KW min / m ² . 0.05KW min /
With a work volume less than m ² , the water absorption hardly improves. On the other hand, if it is more than 2.0 KW min / m ² , an increase in water absorption cannot be obtained despite severe processing conditions. However, the use of the nonwoven fabric for cleaning a printing press blanket is not limited as long as the performance is not impaired.

[0061]

EXAMPLES Hereinafter, the nonwoven fabric for cleaning a printing press blanket of the present invention will be described with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” and “%” mean “parts by weight” and “% by weight”, respectively.

The evaluation method of the nonwoven fabric for cleaning a printing press blanket of the present invention is described below in advance. The words used in Tables 1 to 6 below are as follows. Fiber diameter: The fiber diameter of the ultrafine acrylic fiber is in μm. Fiber length: The fiber length of vegetable cellulose fiber is JAPAN
TAPPI Paper Pulp Test Method No. According to the method described in JP-A-52-89, a Kayani fiber length measuring device (KAJJANI
FS-100). The unit is mm. Aspect ratio; value obtained by dividing fiber diameter by fiber length. Thermal bonding treatment; presence / absence of thermal bonding treatment of nonwoven fabric by heat treatment. EDM processing; work of corona EDM processing, unit is K
W min / m ² .

<Dropping of Fiber at Entangling> The absolute dry weight M1 (g) of the paper-made web was measured, and then the absolute dry weight M2 (g) of the nonwoven fabric obtained after three-dimensional entangling was measured. The difference obtained by subtracting M2 from M1 was divided by M1 to obtain a percentage, and the loss of the fiber was obtained. The unit is%.

<Water Absorption Rate> The water absorption rate is obtained by visually observing the time when specular reflection disappears and only wetness remains as the test piece absorbs the water droplet by dropping water, and the unit is seconds. The test method is as follows. 200 × 2
A test piece of 00 mm is prepared. A test piece is attached to a test piece holding frame specified in JIS L1907. Adjust so that the height from the surface of the test piece to the tip of the burette is 10 mm, drop one drop of water from the burette, and when the water drop reaches the surface of the test piece, the water drop does not reflect specially The time until is measured with a stopwatch. This operation was performed on five test pieces, and the average value was defined as the water absorption rate. The unit is seconds.

<Oil Absorption Rate> In the method for measuring the water absorption rate, a value measured by a method using kerosene instead of water is used.

<Tensile strength during drying> JIS L1
The tensile strength in the longitudinal direction was measured according to the method described in No. 096. However, the width of the test piece was 5 cm and the length was 20 cm, and four test pieces were measured at a grip interval of 10 cm, and the average value was expressed. The unit is N / cm.

<Tensile strength when wet> JIS L1
No. 096, the test piece was spread and immersed in water (20 ± 2 ° C.), allowed to stand for 10 minutes, taken out of the water, and immediately passed through a filter paper (Advantech No. 26).
After pressing lightly to absorb the water on the surface, it is performed within 1 minute by the same method as the measurement of the tensile strength at the time of drying.

<Tensile strength at the time of oil wetting> The tensile strength at the time of water wet was measured in the same manner as in the test except that the test piece was immersed in kerosene.

<Elongation Under Load> In the measurement of tensile strength, the length L1 (cm) of the sample when a load of 5 N / cm is applied is taken. The value obtained by subtracting 10 (cm) from L1 is divided by 10 (cm), and the value expressed as a percentage is defined as the elongation at a constant load. The unit is%.

<Liquid Retaining Property> The liquid retaining property was measured as a retention amount (g / m ² ) by immersing a cleaning liquid obtained by mixing the same amount of kerosene and water in a blanket for cleaning a printing press blanket. First, 10cm
For a test piece having a size of × 10 cm, the weight W1 (g)
Is measured. Next, spread the test piece in the cleaning solution and immerse it.
After leaving it for 10 minutes, it is taken out of the washing solution, immediately sandwiched between filter papers (Advantech No. 26), lightly pressed to absorb the washing solution on the surface, and the weight W2 (g) of the test piece
Was measured. The difference obtained by subtracting the weight W1 (g) from the weight W2 (g) was divided by W1 to obtain a percentage and calculate the retention.
The unit is%.

<Wipeability and printability> A blanket cleaning nonwoven fabric (920 mm width, 13.5 m) of the printing press blanket of the present invention was added to an automatic blanket cleaning machine unit (manufactured by Baldwin Co., Ltd., type ABC-MW) in an offset rotary printing press.
Rolled). A blanket was automatically washed with a cleaning solution (Daiclean, manufactured by Dainippon Ink and Chemicals, Inc.) and water four times in total, and the number of times of feeding was 13 times, and the washing time was 150 seconds. After washing, the blanket surface was visually inspected for the presence of ink stains and paper dust, and for the presence of fibers that appeared to have fallen off the nonwoven fabric. Also,
The state of the surface of the printed matter was visually observed, and this was defined as printability. The wiping property was evaluated as follows: ○: clean without ink stains, paper powder and fibers falling off, ○: slightly clean, ×: ink stains, paper powder remaining, or fibers with falling off . If the nonwoven fabric showed elongation or breakage, the effect was described. In addition, ○ indicates good printability, ○ indicates slightly poor printability, and × indicates disordered printability.

Example 1 As heat-fusible synthetic fibers, the fineness was 0.7 denier (fiber diameter: 10.5 μm) and the fiber length was 10 mm (aspect ratio: about 97
0), an olefin-based synthetic fiber having a core-sheath structure consisting of polypropylene and a sheath made of polyethylene and polyethylene (manufactured by Daiwa Spinning Co., Ltd., NB
FH, sheath melting point 130 ° C.), and as fine acrylic fiber, fineness 0.1 denier (fiber diameter 3.5 μm), fiber length 6
mm (aspect ratio, about 1700) acrylic fiber (manufactured by Mitsubishi Rayon, Bonnell MVP) is 40/60 each.
Was added and mixed in water sequentially to prepare a 1% concentration aqueous slurry. Using this aqueous slurry, a web having a dry weight of 60 g / m ² was formed on an inclined short-mesh paper machine. Next, the papermaking web was loaded on a 76-mesh plain woven plastic wire, and entangled at a pressure (70 kgf / cm ² ) and an entanglement speed of 15 m / min with the following three nozzle rows. Further, the web was inverted, and a water stream was jetted under the same conditions to perform the confounding. The nozzle diameter, nozzle interval, and nozzle arrangement are shown below. The first row has a nozzle diameter of 120μ.
m, the nozzle interval 1.2 mm is arranged in two rows in a staggered manner, the second row has a nozzle diameter of 100 μm, the nozzle interval 0.6 mm is straight in one row, and the third row has a nozzle diameter of 100 μm and the nozzle interval 0.6 mm. One straight line. Then, after squeezing the water with a padder, use an air dryer to
After drying at 0 ° C., 1
Heat treatment was performed at 50 ° C., and the heat-fusible synthetic fibers were bonded to each other or the heat-fusible synthetic fibers were bonded to the microfine acrylic fibers.
After that, the total energy per side is 1.0 KW min / m ²
The corona discharge machining was performed on both surfaces of the nonwoven fabric under the conditions described in (1) to prepare the printing press blanket cleaning nonwoven fabric of Example 1.

Example 2 Example 1 was repeated except that the ultrafine acrylic fiber used in Example 1 was replaced with an acrylic fiber having a fineness of 0.3 denier (fiber diameter 6.1 μm) and a fiber length of 10 mm (aspect ratio, about 1700). In the same manner as in the above, a nonwoven fabric for cleaning a printing press blanket of Example 2 was produced.

Example 3 Example 1 was repeated except that the fine acrylic fiber used in Example 1 was replaced with an acrylic fiber having a fineness of 0.5 denier (fiber diameter 7.9 μm) and a fiber length of 15 mm (aspect ratio, about 1900). In the same manner as in the above, a nonwoven fabric for cleaning a printing press blanket of Example 3 was produced.

Comparative Example 1 Example 1 was repeated except that the fine acrylic fiber used in Example 1 was replaced with an acrylic fiber having a fineness of 0.7 denier (fiber diameter: 9.3 μm) and a fiber length of 15 mm (aspect ratio, about 1600). In the same manner as in Example 1, a nonwoven fabric for cleaning a printing press blanket of Comparative Example 1 was produced.

The nonwoven fabrics for cleaning a printing press blanket obtained in Examples 1 to 3 and Comparative Example 1 were evaluated by the above-described evaluation test. The results are shown in Table 1.

[0077]

[Table 1]

The nonwoven fabric for cleaning a printing press blanket obtained in Examples 1 to 3 is excellent in water absorption / oil absorption and liquid retention.
In addition, since the tensile strength was high when dry, wet and oily, and the elongation under load was suppressed, the wiping properties and printability were good. On the other hand, in Comparative Example 1, since the fiber diameter of the acrylic fiber was out of the range of the present invention, the elongation under load was large, and the surface area of the acrylic fiber was small relative to the whole. As a result, the wiping properties and printability were inferior to those of the present example.

Example 4 Example 1 was repeated except that the ultrafine acrylic fiber used in Example 1 was replaced with an acrylic fiber having a fineness of 0.3 denier (fiber diameter 6.1 μm) and a fiber length of 5 mm (aspect ratio, about 820). In the same manner as in the above, a nonwoven fabric for cleaning a printing press blanket of Example 4 was produced.

Example 5 Example 1 was repeated except that the ultrafine acrylic fiber used in Example 1 was replaced with an acrylic fiber having a fineness of 0.1 denier (fiber diameter 3.5 μm) and a fiber length of 9 mm (aspect ratio, about 2600). In the same manner as in the above, a nonwoven fabric for cleaning a printing press blanket of Example 5 was produced.

Comparative Example 2 Example 1 was repeated except that the ultrafine acrylic fiber used in Example 1 was replaced with an acrylic fiber having a fineness of 0.5 denier (fiber diameter 7.9 μm) and a fiber length of 5 mm (aspect ratio, about 630). In the same manner as in the above, a nonwoven fabric for cleaning a printing press blanket of Comparative Example 2 was produced.

Comparative Example 3 Example 1 was repeated except that the fine acrylic fiber used in Example 1 was replaced with an acrylic fiber having a fineness of 0.1 denier (fiber diameter 3.5 μm) and a fiber length of 12 mm (aspect ratio: about 3400). In the same manner as in the above, a nonwoven fabric for cleaning a printing press blanket of Comparative Example 3 was produced.

The nonwoven fabrics for cleaning a printing press blanket obtained in Examples 4 and 5 and Comparative Examples 2 and 3 were evaluated by the evaluation test described above. The results are shown in Table 2.

[0084]

[Table 2]

The nonwoven fabric for cleaning a printing press blanket obtained in Examples 4 and 5 is excellent in water absorption / oil absorption and liquid retention.
In addition, since the tensile strength was high when dry, wet and oily, and the elongation under load was suppressed, the wiping properties and printability were good. On the other hand, in Comparative Example 2, since the aspect ratio of the acrylic fiber was not more than the range of the present invention, many acrylic fibers fell off, resulting in reduced water absorption and poorer wiping properties and printability than those of this example. It became. Further, in Comparative Example 3, since the aspect ratio was not less than the range of the present invention, a uniform web could not be formed in the wet papermaking stage, and a non-uniform nonwoven fabric for cleaning a printing press blanket having uneven fibers was obtained. And the printability was inferior to that of this example.

Comparative Example 4 A nonwoven fabric for cleaning a printing press blanket of Comparative Example 4 was produced in the same manner as in Example 1 except that the heat treatment at 150 ° C. performed in Example 1 was not performed.

Comparative Example 5 A nonwoven fabric for cleaning a printing press blanket of Comparative Example 5 was produced in the same manner as in Example 1 except that the corona discharge treatment performed in Example 1 was not performed.

The nonwoven fabrics for cleaning a printing press blanket obtained in Comparative Examples 4 and 5 were evaluated by the above-described evaluation test, and the results are shown in Table 3.

[0089]

[Table 3]

Compared with the nonwoven fabric for cleaning a printing press blanket of Example 1, Comparative Example 4 had a low breaking strength, so that the cleaning liquid and water were sprayed during the wiping test to break the nonwoven fabric. The nonwoven fabric for cleaning a printing press blanket of Comparative Example 5 was inferior in water absorption, so that the cleaning liquid from the automatic blanket washing machine could not be sufficiently absorbed during the wiping test. Therefore,
A lot of paper dust that could not be wiped off was noticeable on the blanket.

Example 6 As heat-fusible synthetic fibers, a fineness of 0.7 denier (fiber diameter of 10.5 μm) and a fiber length of 10 mm (aspect ratio, about 97
0), an olefin-based synthetic fiber having a core-sheath structure consisting of polypropylene and a sheath made of polyethylene and polyethylene (manufactured by Daiwa Spinning Co., Ltd., NB
FH, sheath melting point 130 ° C.), and as fine acrylic fiber, fineness 0.1 denier (fiber diameter 3.5 μm), fiber length 6
mm (aspect ratio, about 1700) acrylic fiber (manufactured by Mitsubishi Rayon, Bonnell MVP) and bleached kraft pulp (NBKP) having a weight average fiber length of 2.1 mm as vegetable cellulose fiber in a ratio of 20/40/40. A nonwoven fabric for cleaning a printing press blanket of Example 6 was prepared in the same manner as in Example 1 except for the above.

Example 7 The vegetable cellulose fibers used in Example 6 were converted to hydrophilic synthetic fibers at a fiber denier of 0.7 denier (a fiber diameter of 8.1 μm).
m) A nonwoven fabric for cleaning a printing press blanket of Example 7 was produced in the same manner as in Example 6, except that rayon fibers (Corona, manufactured by Daiwabo Rayon) having a fiber length of 10 mm (aspect ratio: about 1200) were used.

The nonwoven fabric for cleaning a printing press blanket obtained in Examples 6 and 7 was evaluated by the above-described evaluation test, and the results are shown in Table 4.

[0094]

[Table 4]

The nonwoven fabric for cleaning a printing press blanket obtained in Examples 6 and 7 is superior to the nonwoven fabric obtained in Example 1 in water absorption / oil absorption properties and liquid retention properties. Since the elongation at the time was suppressed, the wiping property and the printing property were very good.

Example 8 Example 6 was repeated except that the vegetable cellulose fiber used in Example 6 was replaced with LBKP having a weight average fiber length of 1.3 mm.
In the same manner as in the above, a nonwoven fabric for cleaning a printing press blanket of Example 8 was produced.

Example 9 Example 6 was repeated except that the vegetable cellulose fiber used in Example 6 was replaced with NBKP having a weight average fiber length of 1.7 mm.
In the same manner as in the above, a nonwoven fabric for cleaning a printing press blanket of Example 9 was produced.

Example 10 Example 6 was repeated except that the vegetable cellulose fibers used in Example 6 were replaced with hemp pulp having a weight average fiber length of 2.5 mm.
In the same manner as in the above, a nonwoven fabric for cleaning a printing press blanket of Example 10 was produced.

The nonwoven fabric for cleaning a printing press blanket obtained in Examples 8 to 10 was evaluated by the above-described evaluation test. The results are shown in Table 5.

[0100]

[Table 5]

From Examples 8 to 10, it was found that an excellent nonwoven fabric for cleaning a printing press blanket can be obtained even if the fiber length of the vegetable cellulose fiber is changed. In particular, Example 9,
The nonwoven fabric for cleaning a printing press blanket obtained in Step 10 has a small amount of fibers falling off and has excellent water absorption / oil absorption properties and liquid retention properties.
The wiping properties and printability were also good.

Example 11 The procedure of Example 7 was repeated except that the hydrophilic synthetic fiber used in Example 7 was replaced by rayon fiber having a fiber length of 0.7 denier (fiber diameter 8.1 μm) and a fiber length of 3 mm (aspect ratio: about 370). In the same manner as in Example 7, the nonwoven fabric for cleaning a printing press blanket of Example 11 was produced.

Example 12 Example 12 was repeated except that the hydrophilic synthetic fiber used in Example 7 was replaced with rayon fiber having a fiber density of 0.7 denier (fiber diameter 8.1 μm) and a fiber length of 5 mm (aspect ratio, about 620). In the same manner as in Example 7, the nonwoven fabric for cleaning a printing press blanket of Example 12 was produced.

Example 13 Example 13 was repeated except that the hydrophilic synthetic fiber used in Example 7 was replaced with rayon fiber having a fiber length of 1.5 denier (fiber diameter: 11.8 μm) and a fiber length of 10 mm (aspect ratio: about 850). In the same manner as in Example 7, the nonwoven fabric for cleaning a printing press blanket of Example 13 was produced.

The nonwoven fabric for cleaning a printing press blanket obtained in Examples 11 to 13 was evaluated by the above-described evaluation test, and the results are shown in Table 6.

[0106]

[Table 6]

From Examples 11 to 13, it was found that an excellent nonwoven fabric for cleaning a printing press blanket can be obtained even when the fiber length of the vegetable cellulose fiber is changed. In particular, it was found that the nonwoven fabric for cleaning a printing press bracket obtained in Examples 7 and 8 has a small amount of fibers falling off, and a nonwoven fabric for cleaning a printing press blanket having a high wiping property can be obtained.

[0108]

The nonwoven fabric for cleaning a printing press blanket of the present invention is mainly made of ultrafine acrylic fiber and heat-fusible synthetic fiber, three-dimensionally entangled and heated, and further subjected to electric discharge machining. It has a water absorption / oil absorption rate based on the dropping method of JIS L1907, has a high tensile strength when dry, wet and oily, and realizes a low elongation under a constant load. When used in an automatic blanket washing machine in a printing machine, it does not tear or remarkably elongate during washing, has excellent washing liquid retention properties, does not drop off fibers, and has an excellent effect of wiping off ink stains. It is.

Claims (6)

[Claims] Claims: 1. A heat-fusible synthetic fiber having an aspect ratio of 70
It contains ultrafine acrylic fibers having a fiber diameter of 0 to 3000 and a fiber diameter of 8.0 μm or less, and these fibers are uniformly mixed, three-dimensionally entangled with each other, and at least a part of the heat-fusible synthetic fibers is heat-fused synthetic fibers. After adhering the fibers to each other and the ultrafine acrylic fiber, at least one surface is subjected to electric discharge machining, and the JIS L
Both the water absorption rate measured by the dropping method of 1907 and the oil absorption rate measured using kerosene by a method based on the dropping method are 10 seconds or less, and when dry, wet, or wet. Also has a tensile strength of 15 N / cm in the vertical direction
A nonwoven fabric for cleaning a printing press blanket, wherein the elongation at a load of 5 N / cm in the longitudinal direction is suppressed to within 3.0%. 2. The nonwoven fabric for cleaning a printing press blanket according to claim 1, comprising one or more vegetable cellulose fibers or hydrophilic synthetic fibers. 3. The nonwoven fabric for cleaning a printing press blanket according to claim 2, wherein the weight average fiber length of the vegetable cellulose fibers is 1.5 mm or more. 4. The aspect ratio of the hydrophilic synthetic fiber is 500.
The nonwoven fabric for cleaning a printing press blanket according to claim 2, which is as described above. 5. The heat-fusible synthetic fiber has an aspect ratio of 70.
0 to 3000, ultrafine acrylic fibers having a fiber diameter of 8.0 μm or less are uniformly dispersed in water, made into a web by a wet papermaking method, loaded on a porous support, and jetted with a high-pressure columnar water stream, A nonwoven fabric for cleaning a printing press blanket, characterized in that after the fibers are three-dimensionally entangled, moisture is removed, the fibers are treated at a temperature higher than the melting point of the heat-fusible synthetic fibers, and then at least one surface is subjected to electrical discharge machining. Manufacturing method. 6. The method for producing a nonwoven fabric for cleaning a printing press blanket according to claim 5, which comprises at least one of vegetable cellulose fibers and hydrophilic synthetic fibers.