JPH07166467A - Production of plated nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain plated nonwoven fabric having improved fluff and removal of fibers by subjecting organic fibers to catalytic treatment of electroless plating, making the organic fibers into a sheet and carrying out electroless plating. CONSTITUTION:Before organic fibers such as wood pulp, synthetic fibers or regenerated fibers are subjected to electroless plating, for example, the organic fibers are immersed in a solution of palladium chloride, reduced, provided with a palladium catalyst, then made into a sheet, interlaced in a three dimensional way to give pretreated nonwoven fabric made into a sheet. Then the nonwoven fabric is subjected to electroless plating to give plated nonwoven fabric having improved adhesiveness of plated layer and little fluff without using a catalyst in a high concentration. Plated nonwoven fabric having excellent flexibility can be obtained by interlacing the nonwoven fabric made into a sheet by water flow after the forming the sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a plated non-woven fabric in which fibrous material is formed into a sheet.

[0002]

2. Description of the Related Art Heretofore, as a conductive sheet, there has been known a conductive paper obtained by mixing carbon fibers or fibrous metals with fibrous substances such as pulp to make paper (Japanese Patent Publication No. Sho 32-32766). (See Japanese Kokoku Publication No. 49-32766, etc.), high conductivity was not obtained, and it was limited only to use as an antistatic material. Recently, many composites composed of a conductive fiber and a fibrous binder of a polymeric substance have been proposed (JP-A 61-127199 and JP-A 61-22).
5398, etc.), the conductivity has improved,
In order to obtain high conductivity, many expensive fibrous metals such as Ni-plated carbon fiber and stainless fiber are used, which is inevitably expensive. In addition, plated organic fibers have come to be commercially available, but even if the plated fibers alone are made into a sheet, the strength cannot be obtained, and the conductivity is limited because the binder polymer is inevitably added.

Recently, a number of sheets have been proposed in which organic fibers are formed into a woven or non-woven sheet and then plated. In this case, the plating process including pretreatment such as catalyst treatment is long, and the catalyst treatment requires the use of a high-concentration catalyst solution and an activating solution using a strong acid of 1N or more. Therefore, it was necessary to remove the treatment liquid of the previous step by washing with water.
However, since woven and non-woven fabrics have many fine voids and a large specific surface area, it is difficult to completely wash them with water in the case of continuous treatment, and the fatigue of the plating solution caused by bringing in the catalyst solution, activation solution, etc. There was a limit to the improvement of processing capacity. Also, with a thick sheet, the amount of catalyst liquid retained inside the voids is large,
The amount of expensive catalyst liquid washed with water was large and wasted. Furthermore, in each processing solution, uneven processing occurs due to the concentration gradient in the cross-sectional direction, and if it is necessary to perform sufficient processing on the inside, it is necessary to use a catalyst solution with a higher concentration than necessary, and the surface is overtreated. , It takes a long time to activate,
There is a problem that the plated layer is crushed and a smooth plated layer cannot be obtained. For this reason, it was mainly a thin sheet, but the adhesion of the plating layer was poor due to the type of fiber,
In particular, it could not be practically used in the case of polyolefin fiber.

[0004]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In a method for producing a plated sheet obtained by plating a fiber assembly composed of organic fibers, the step of forming a sheet and the step of electroless plating are examined,
Prevents deterioration of the plating solution due to mixing of pretreatment solution into the plating solution, such as applying a catalyst for electroless plating, improves productivity, improves the adhesiveness of the plating layer, and improves the fluffing and falling of the plating fiber. It is an object of the present invention to provide a method for producing a plated non-woven fabric sheet.

[0005]

Means for Solving the Problems The present inventors have diligently studied the above problems. As a result, before the sheet is formed, the fiber is pretreated by applying a catalyst such as electroless plating, and then formed into a sheet, and then the sheet is plated, so that a uniform concentration can be obtained in the cross-sectional direction without using a high-concentration catalyst solution. It was found that a catalyst-treated plated sheet was obtained, and as a result, it was possible to immediately produce a plated sheet excellent in productivity, which enables various kinds of plating on the same sheet. It was also found that by performing hydroentangling treatment after forming the sheet, it is possible to produce a plated sheet having a high porosity without fluffing or dropping of the fibers.

That is, the present invention is a method for producing a plated non-woven fabric, which uses fibers pretreated by electroless plating, such as catalytic treatment, and is formed into a sheet and then plated. Furthermore, the present invention is a method for producing a plated non-woven fabric, which is formed into a sheet by a wet papermaking method using a slurry prepared by pre-treating fibers with electroless plating and containing the treatment solution. Further, the present invention is a method for producing a plated non-woven fabric, which is formed into a sheet and then three-dimensionally entangled.

Next, the present invention will be described in more detail in the order of steps. In the present invention, the fibers are pre-treated by electroless plating in advance, then formed into a sheet, and then electroless plated to produce a plated sheet.

The fibers used for the non-woven fabric include wood pulp, polyester fibers, polyolefin fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, nylon fibers, regenerated cellulose fibers, and other organic fibers.
Alternatively, an inorganic fiber such as glass fiber may be used. Polyester fiber, polyethylene terephthalate, polybutylene terephthalate, a fiber composed of homopolymers and copolymers such as modified polymers of these polymers,
Polyolefin fibers are fibers made of homopolymers and copolymers such as polypropylene, polyethylene, polystyrene, and modified polymers thereof. The polyacrylonitrile fibers are acrylic fibers, modacrylic fibers, etc., the polyvinyl alcohol fibers are fibers made of polyvinyl alcohol, and the polyamide fibers are fibers made of polymers such as nylon 6 and nylon 66.

These fibers may be in the form of composite fibers composed of two or more kinds of polymers described above, for example, fibers having a core-sheath structure of polypropylene fibers and polyethylene fibers, polyethylene terephthalate fibers and polyethylene fibers. The cross-sectional shape may be not only a circular shape or an elliptical shape, but also a so-called atypical cross-sectional shape such as a triangular shape, a Y-shape, a T-shape, a U-shape, a star shape, and a dogbone shape. The fiber diameter and fiber length of these fibers are produced in an appropriate size according to the sheeting method, and they can be mixed and used as needed.

Further, synthetic pulp can also be used. Synthetic pulp is a synthetic fiber that is a polymer that can be opened from fibrillation of various synthetic fibers, for example, jet spinning method of the melt spinning method of the spinning method, mixed spinning method, ordinary uniaxial stretching method of the film method, Synthetic fibers produced by a flash spinning method, which is a self-pressure method of a solution method, which is a synthetic fiber that can be opened by a refiner, and can be formed into a sheet by a wet papermaking method in the same manner as wood pulp. As the synthetic pulp, in particular, a polyolefin-based synthetic fiber is often used, which itself has a heat-fusible property and can be used as a heat-fusible sheet.

In the present invention, a pretreatment of electroless plating is performed before forming these fibers into a sheet.

Usually, the electroless plating process basically consists of two steps, that is, a pretreatment step for applying catalyst nuclei and an electroless plating step. However, when plating a plate-shaped substrate such as a printed circuit board or a plastic container, Is a conditioning process for cleaning / degreasing the surface of the substrate with sodium hydroxide, etc., a micro-etching process with sulfuric acid or chromic acid for roughening to obtain an anchor effect on the plating layer, and a catalyst solution deterioration prevention Pre-treatment process such as pre-dip process, activation process with sulfuric acid for activation of catalyst, acid such as sodium hydroxide, alkali, etc. is added, and washing, draining, drying, etc. between each process as necessary. Is added. In the present invention, basically, a pretreatment step is performed in a fiber state, and a step of electroless plating after forming into a sheet is performed. After electroless plating, if necessary, antirust treatment or electroless plating or electroplating of a metal having good durability can be performed to improve durability and increase the plating film thickness.

In the present invention, catalyst nuclei are previously formed on the fiber surface. As such a catalyst nucleus, a standard electrode potential in an aqueous solution of a metal or a metal sulfide has a value close to or larger than the value of the plated metal, preferably gold,
Silver, copper, platinum, palladium, nickel, and as the sulfide, silver sulfide, copper sulfide, palladium sulfide, cobalt sulfide, nickel sulfide, zinc sulfide, or a complex nucleus of these sulfides can be used. Among these, palladium is particularly widely used because it has a great effect as a catalyst on various kinds of plating metals.

When palladium is used as the catalyst nucleus, the catalyst is attached to the fiber surface by the following various methods. As a method of applying a catalyst, for example, a method of immersing the fiber in an aqueous solution of palladium chloride and then immersing it in an aqueous solution of a reducing agent to precipitate the metal nuclei (JP-A-49-126999), palladium chloride and active A reducing agent is added to an aqueous solution containing an agent to form a colloidal dispersion of palladium metal, and then fibers are immersed in this aqueous solution to deposit palladium nuclei to form catalyst nuclei (“Chemical and Industrial”). p430, vo
l.42, 1989), but in the present invention, the sensitizing-activator method and the catalyst-accelerator method (“Latest Surface Treatment Technology Overview” industry) have good adsorptivity of catalyst nuclei in water and are hard to drop off. Technical service center
p225, December 12, 1987) is particularly preferred. In the sensitizing-activator method, the fiber is previously dipped in an aqueous solution of tin (II) chloride, and then dipped in an aqueous solution of palladium (II) chloride to deposit palladium metal nuclei. In the catalyst-accelerator method, the fibers are immersed in an aqueous solution of palladium (II) chloride colloidally dispersed in an excess tin (II) chloride solution, and then immersed in an aqueous solution of sulfuric acid, sodium hydroxide or the like. Precipitate palladium metal nuclei. It is sufficient that the amount of the catalytic metal attached is 0.1 g / m ² or less in terms of the weight of the catalytic metal with respect to the surface area of the fiber.

The pretreatment for applying the catalyst to the fibers may be carried out by immersing the fibers in the above-mentioned catalyzed treatment liquid and stirring them so that the treatment can be carried out uniformly. The pretreatment for applying a catalyst may be carried out by sequentially immersing the mixture in the sensitizing solution and the activator solution, or in the catalyst solution and the accelerator solution, followed by stirring. It is preferable to filter, discard, and wash with water. Alternatively, only the treatment with the sensitizing liquid or the catalyst liquid may be applied to the fibers, and after forming into a sheet, the fibers may be treated with an activator liquid or an accelerator liquid, respectively. Further, it is also possible to continuously carry out a pretreatment for applying a catalyst when the fiber is spun. After the catalyst pretreatment, it is filtered and dried in the case of the dry papermaking method, but in the case of the wet papermaking method, it is not dried, and the liquid after the catalyst pretreatment is diluted while leaving a little, and the slurry remains wet. It is more preferable to prepare the above because the dispersibility of the fiber is better. When different types of fibers are mixed to form a sheet, it is preferable to treat them separately after considering the adsorbability of the catalyst.

The fibers that have been subjected to the electroless plating pretreatment as described above are then formed into a sheet. As a method for producing a nonwoven web sheet, a wet papermaking method using the fibers, a dry heat or wet heat bonding method, or a dry papermaking method such as a card method, a cross layer method, a random webber method, a spunbond method, or the like, is known. The production method can be used, and if necessary, the fibers can be fixed by a three-dimensional entanglement treatment such as needle punching or primary water entanglement treatment. Fiber diameter and fiber length differ depending on the manufacturing method, and the characteristics of the resulting nonwoven fabric such as texture, thickness range, porosity, void shape, pore size, homogeneity, flexibility, elasticity, fluffing, and fiber dropout Since they are different, any manufacturing method is selected depending on the required characteristics.

In particular, in the case of the wet papermaking method, fibers dispersed in a large amount of water in a slurry form can be filtered with a mesh and further transferred to a canvas or the like to form a continuous sheet. The wet papermaking process is just a continuous filtration process, in which the treatment liquid used in the fiber pretreatment flows out together with a large amount of water, and the residual pretreatment liquid can be washed unexpectedly. The wet papermaking method has high productivity and can produce a uniform web.

In the wet papermaking method, a surfactant, a thickening agent or, if necessary, binder fiber is further added to the catalyst-treated fiber and dispersed in water to prepare a slurry. The slurry thus prepared is made into paper by using a Fourdrinier paper machine, a cylinder paper machine, etc., and the formed web is a Yankee dryer,
Using a multi-cylinder type cylinder dryer, an air dryer, etc., a web sheet is dried by a usual drying method.

In the case of a three-dimensional entangled non-woven fabric substrate, binder fibers that can be dissolved and removed in the entanglement treatment stage, such as polyvinyl alcohol fibers that dissolve and flow out with hot water, can be mixed to strengthen the substrate. preferable.

When the web is produced by the wet papermaking method,
The fiber length of the fibers that can be used is 1 to 50 mm. Fibers having a fiber length of more than 50 mm are not preferable because the fibers are entangled during the dispersion of the fibers. Further, in the case of performing a three-dimensional entanglement treatment, if the fibers are too short, they fall off during the entanglement, and the entanglement becomes insufficient, resulting in a decrease in strength. Ranges are preferred. Longer fibers are used in the dry papermaking method, and the fiber length is not particularly limited.

Next, the three-dimensional confounding process will be described. Three
Dimensional entanglement treatment is a single layer of the above web, or a plurality of laminated, placed on a support, mechanical treatment to the web,
This is a method of three-dimensionally entangled fibers, and specific examples thereof include a needle punch method and a water entanglement method. The needle punch method is a method in which a large number of needles are pierced from above the web to three-dimensionally entangle the fibers constituting the web to develop strength, and the hydroentanglement method is to jet a large number of thin water streams from above the web. , Three-dimensionally entangle the fibers that make up the web,
This is a method of expressing strength. The hydroentangling method is preferred for the present invention because even the fine fibers can be uniformly entangled and the production rate is high. Further, if necessary, water entangling can be further performed after the needle punching.

In the dry papermaking method such as the card method, since the fiber length is long, entanglement naturally occurs even if it is not entangled, and it has some strength. In this case, the fibers are arranged in layers in the upper and lower layers, and the fibers are separated from each other after drying. Therefore, a binder polymer or binder fibers are added to obtain tensile strength. On the other hand, when the entanglement treatment is performed, the upper and lower fibers are entangled with each other, and the strength is developed even if the binder is not added. Moreover, as a result of the fibers being bent up and down and entangled with each other, the voids also expand up and down, resulting in a flexible nonwoven fabric rich in fluffy voids. The three-dimensional entanglement treatment can impart tensile strength to a sheet having a low density and requiring a certain amount of thickness, which is also preferable when manufacturing a porous substrate.

The conditions for firmly and properly performing the entanglement by the hydroentanglement method will be described below. The diameter of the nozzle for jetting the water flow is preferably in the range of 10 to 500 μm. The distance between the nozzles is preferably 10 to 1500 μm. Further, the shape of the nozzle is preferably circular, and a so-called columnar water jet is preferable. The support on which the web is loaded is preferably a porous support of about 50 to 200 mesh.

These nozzles need a range that covers the width of the sheet to be processed in the direction orthogonal to the papermaking direction. Considering the papermaking direction, the type of web, the basis weight, the processing speed, and the water pressure are taken into consideration. The number of nozzle heads can be changed and used within a range where sufficient entanglement can be obtained.

The water pressure is preferably used in the range of 10 to 250 kg / cm ² . More preferably 50-250 kg /
It is cm ² . The processing speed is preferably used in the range of 5 to 200 m / s.

The water pressure is preferably increased from the beginning of the process to the end thereof so that the surface quality is improved. In addition, it is also possible to successively reduce the nozzle diameter or the nozzle spacing, or both the nozzle diameter and the nozzle spacing, which is also preferable in that the surface quality of the nonwoven fabric is improved. Further, the surface quality can be further improved by rotating the header of the nozzle or by vibrating the wire to the left and right. Also, insert a wire between the nozzle and the web to spray the water flow,
The surface quality can also be improved by using a fan-shaped water stream.

The entanglement processing can be performed on only one side or on both sides. After the entanglement, it is possible to further entangle the webs obtained by different methods of manufacturing the base material web, if necessary.

Next, the electroless plating solution used in the present invention will be described. Generally, an electroless plating solution is prepared using a metal ion source and a reducing agent as main components and a complexing agent, a pH adjusting agent, a buffering agent, an accelerator, a stabilizer, an improving agent, etc. as auxiliary components. .

In the electroless plating solution of the present invention, as the metal ion source, there are copper sulfate, nickel sulfate, cobalt sulfate, nickel chloride, palladium chloride, silver chloride, silver nitrate, and mixtures thereof. It is used according to the type. A metal having good conductivity is selected as the electromagnetic shield material, and metal ions such as silver, copper and nickel are generally used. Depending on the type of these metal ion sources, the following complexing agents, reducing agents, and other additives are properly selected.

Examples of complexing agents include sodium citrate, potassium citrate, organic acid salts such as Rochelle salt, thioglycolic acid, ammonia, triethanolamine, glycine,
There are ethylenediamine, ethylenediamine diacetate, o-aminophenol, pyridine and the like. In the case of silver plating, the complexing agent is thiosulfate, thiocyanate, sulfite, thiourea, potassium iodide, thiosalicylic acid, Thiocyanuric acid and the like can also be used.

Examples of the reducing agent include sodium hypophosphite, sodium borohydride, potassium borohydride, Rochelle salt, dimethylamine borane, diethylamine borane, formalin, and hydrazine compounds such as hydrated hydrazine, hydrazine hydrochloride, hydrazine sulfate and methyl. Hydrazine, 1,2-dimethylhydrazine, acetohydrazine, phenylhydrazine and the like can be used as reducing agents such as hydroquinone and glucose.

In the present invention, the compounding amount of the metal ion in the plating solution is 0.001 to 0.2 mol / l, and the compounding amount of the complexing agent is 0.001.
˜4.0 mol / l, and the reducing agent preferably ranges from 0.001 to 0.4 mol / l.

As the pH adjusting agent, sodium hydroxide, ammonium hydroxide, inorganic acid, organic acid and the like are preferable. As a buffering agent, an organic acid, an inorganic acid alkali metal salt,
Sodium citrate, sodium acetate, ammonium chloride, ammonium sulfate, oxycarboxylic acid, dihydrogen phosphate, boric acid and carbonic acid are used to alleviate abrupt changes in pH during plating. The promoter is added to suppress the generation of hydrogen, and sulfides, fluorides, etc. are used.

As the stabilizer, lead chloride, sulfide, nitrification, 2,2'-bipyridine, 2-mercaptobenzothiazole, nicotinic acid, etc. are added in trace amounts. Further, as a modifier, a surfactant is added to copper plating or the like to improve the smoothness of the plating surface, but a trace amount is sufficient,
If the amount is too large, there is a risk of inhibiting plating deposition.

In the present invention, electroplating may be further performed after electroless plating. Electroplating has a simpler and more stable plating liquid composition than electroless plating, and the growth of the plating layer is fast, and liquid management is easy, and the amount of plating can be controlled by the applied current.
It can be used when making a thick film plating layer.

Examples of the electroplating solution include copper pyrophosphate, copper cyanide bath, copper sulfate bath and other copper plating solutions, Watts bath, chloride bath,
A nickel plating solution such as a sulfamic acid bath, a chromium plating solution such as a Sargent bath, or a plating solution such as gold, silver, tin or zinc can be used.

[0037]

EXAMPLES The plated nonwoven fabric of the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Examples 1 to 3 Polyolefin-based composite fiber having a fiber diameter of 2d (fiber diameter 15 μm) and a fiber length of 20 mm (core-sheath type composite fiber of Chisso EA, core polypropylene, sheath ethylene vinyl acetate, manufactured by Chisso Corporation). , Polyester binder fiber (Melty 4080, core-sheath type, sheath melting point 11
0 ° C., manufactured by Unitika Ltd.) and dried, and then polyolefin-based composite fiber / polyester binder fiber = 80/2
It was adjusted to 0 (weight ratio) and immersed in a 1.8% hydrochloric acid aqueous solution so as to have a fiber concentration of 1.5% (hereinafter, all weight%). Then, the mixture was stirred for 3 minutes with a high-speed mixer to disaggregate the fibers, and then gently stirred in a chest equipped with a reciprocating rotary stirrer (Agitator, manufactured by Shimazaki Seisakusho).

Next, a 1N hydrochloric acid solution of 1.5% of the catalyst liquid MK220 (hydrochloric acid-based colloidal solution of palladium chloride and tin chloride) manufactured by Muromachi Chemical Co., Ltd. was added to 40% of the fiber slurry liquid.
The mixture was added and stirred for 20 minutes. Next, while filtering, the water content is reduced to 5% or less, and an accelerator solution (30 ° C.) of a 1% sulfuric acid aqueous solution is added until the fiber concentration reaches 1.5%.
After stirring for a minute, pretreatment for applying a catalyst was performed.

After filtering again to reduce the water content to 5% or less, water was added to prepare a 1.5% slurry of the pretreated fiber. Subsequently, the mixture was gently stirred, and an aqueous 0.1% acrylamide solution (sticking agent) was appropriately added while diluting to prepare a catalyst-treated pretreated fiber slurry having a fiber concentration of 0.15%. Using the fiber slurry, a cylinder paper machine produces a basis weight of 50 g.
/ M ² web made into paper, 130 ° C with Yankee dryer
To obtain a wet-processed non-woven fabric pretreated by electroless plating.

Next, the following electroless plating solutions (1) and (2)
And (3) were prepared, each of the above pretreated nonwoven fabrics was immersed in each plating solution for 15 minutes and then washed with water to form a silver-plated nonwoven fabric (Example 1), a copper-plated nonwoven fabric (Example 2), a nickel-plated nonwoven fabric ( Example 3) was obtained. Examples 1-3
The surface of the plated sheet obtained in 1. was subjected to an adhesiveness test with cellophane tape. No peeling of the plating layer was observed, and it was found that the inside was uniformly plated in the cross-sectional direction. In addition, when the electromagnetic wave shielding characteristics were measured, both were 60 dB over the range of 30 to 1000 MHz.
It was found that the above excellent characteristics were exhibited.

Electroless silver plating solution (1) Solution A Silver chloride 8 g / l Sodium sulfite 160 g / l Solution B Hydrazine sulfate 10 g / l Solution A and solution B are mixed 1: 1 pH 7.6 Solution temperature 20 ° C.

Electroless copper plating solution (2) (electroless copper plating solution made by EBARA Eugelite) PB503A 100cc / l PB503B 100cc / l Solution temperature 25 ° C

Electroless Nickel Plating Solution (3) Nickel Sulfate 20 g / l Sodium Citrate 30 g / l Sodium Hypophosphite 15 g / l Ammonium Chloride 30 g / l Prepared to pH 9.5 with Aqueous Ammonia Solution Temperature 50 ° C.

Comparative Example 1 A slurry was prepared without pretreating the fibers in Example 1 to obtain a wet-processed nonwoven fabric. This non-woven fabric is used in Example 1.
Was immersed in the same catalyst solution as above, washed with water, then immersed in the same accelerator solution as in Example 1, washed with water, and then subjected to electroless plating in the same manner as in Example 1, and only the surface was plated. Could not be plated. In this case, it was found that the concentration of the treatment liquid was too low to carry out catalytic treatment to the inside in the cross-sectional direction. From this, it was confirmed that the present invention can uniformly apply the catalyst to the fiber surface even if a low-concentration catalyst is used, and that even after plating into a sheet, the inside of the sheet can be uniformly plated in the cross-sectional direction of the sheet.

Example 4 Polyethylene synthetic pulp (SWP-E620, manufactured by Mitsui Petrochemical Co., Ltd.), wood pulp (NBKP) and a fiber density of 0.2 d
Polyacrylonitrile fibers having a fiber diameter of 7 μm and a fiber length of 10 mm were separately immersed in a 1.8% hydrochloric acid aqueous solution so as to have a concentration of 1.5%. Then, each with a high speed mixer 3
After stirring for 1 minute to disaggregate the fibers, the fibers were gently stirred in a chest equipped with a reciprocating rotary stirrer (Agitator, manufactured by Shimazaki Seisakusho).

Next, a 1N hydrochloric acid solution of 1.5% catalyst liquid MK220 (a saline colloidal solution of palladium chloride and tin chloride) manufactured by Muromachi Chemical Co., Ltd. was added to each of 40% of the fiber slurry liquid and stirred for 20 minutes. . Then, while filtering, the water content is reduced to 5% or less, and then an accelerator solution (temperature: 30 ° C.) of a 0.5% sulfuric acid aqueous solution is added to each until a fiber concentration of 1.5% is added, and the mixture is stirred for 30 minutes, Pretreatment with catalyst application was performed.

After filtering again to reduce the water content to 5% or less, water was added to prepare 1.5% slurries of the pretreated fibers. Next, the volume ratio of the polyethylene synthetic pulp slurry / wood pulp slurry / polyacrylonitrile fiber slurry prepared respectively was 50/20.
The mixture was mixed at a ratio of 30/30, followed by gentle stirring, and an aqueous 0.1% acrylamide solution (sticking agent) was appropriately added while diluting to prepare a 0.15% catalyst-treated pretreated fiber slurry. A width of 50 with a cylinder paper machine using the slurry.
A web having a cm and basis weight of 40 g / m ² was made into a paper and dried with a Yankee dryer at 90 ° C. to obtain a catalyst-treated nonwoven fabric. When the void diameter was measured, the maximum void diameter was 250.
and the average void diameter was 70μ.

Next, it was immersed in the electroless plating solution (2) used in Example 2 and plated with copper for 6 minutes to obtain a heat-fusible conductive sheet. When the sheet was cut and the voids appearing in the cross section were observed with a microscope, it was found that even though the catalyst liquid and the accelerator liquid with low concentrations were used, they were uniformly plated on the front and back. .

The two sheets of the heat-fusible conductive sheet thus obtained were subjected to thermocompression bonding at 140 ° C. for 1 minute to form a sheet having a joint and the electrical conductivity and peel strength (angle) of the joint. The value of 180 degrees) is 150 S /
The values are cm and 2.0 kg / 50 mm. Moreover, when the electromagnetic wave shielding characteristics were measured, all were 30 to 1000M.
Shows excellent characteristics of 40 dB or more over the range of Hz,
It has been found that in practical use, an excellent electromagnetic shield material with a large area that exceeds the manufacturing size can be obtained.

Example 5 A polyacrylonitrile fiber having a fiber density of 0.2 d (fiber diameter 7 μ) and a fiber length of 10 mm was used to prepare a 1.5% slurry of the catalyst-treated fiber in the same manner as in Example 1.

Next, the hot water-soluble polyvinyl alcohol (PVA) fiber was impregnated in a 1% solution of the nonionic dispersant, and then put into water and stirred for 3 minutes with a high speed mixer.
The fibers were disaggregated. This fiber was added to the pretreated fiber slurry so as to be 3% with respect to the above fiber, and gently stirred in a chest with a reciprocating rotary stirrer (Agitator, manufactured by Shimazaki Seisakusho). Subsequently, the mixture was gently stirred, and while being diluted, a 0.1% polyacrylamide aqueous solution (sticking agent) was appropriately added to prepare a 0.15% fiber slurry. A web having a width of 50 cm and a basis weight of 40 g / m ² was subjected to a catalyst treatment to produce a nonwoven fabric substrate using the slurry using a cylinder paper machine.

Next, two layers of the web were laminated, and three nozzle heads were used for entanglement with a columnar water stream. The nozzle of the first head has a nozzle diameter of 120 μm, a nozzle spacing of 1.2 mm, and 2
Water pressure is 100 kg / cm ^{2 in} a row, the second head has a nozzle diameter of 120
μm, Nozzle spacing 0.6 mm, Water pressure 100 kg / cm per row
² , the third head has a nozzle diameter of 100 μm and a nozzle spacing of 0.
The water pressure is 120 kg / cm ² in a row of 6 mm. Place a 100 mesh stainless steel support under the laminated web,
The polyvinyl alcohol binder was eluted while the fibers were entangled while passing through the laminated web under the above water flow. Similarly, the same processing was performed on the back surface. The entanglement speed was 20 m / min. This entangled sheet was dried at 90 ° C. using a suction through dryer to obtain a hydrolyzed nonwoven fabric with catalyst treatment.

Next, the electroless plating solution (2) used in Example 2 was dipped, and after copper plating for 15 minutes, it was washed with water and further dipped in a rust preventive agent to obtain a hydroentangled copper plating sheet. When the sheet was cut, and the voids appearing in the cross section were observed with a microscope, it was found that the fibers that were locally entangled densely due to the hydroentangling treatment despite the use of a low concentration catalyst solution or accelerator solution. It was found that the plating was evenly distributed between them. A conductive adhesive was applied to one side of the sheet, and the sheet was pasted as an electromagnetic shield gasket and tested.
It exhibited excellent characteristics of 0 dB or more.

Comparative Example 2 The fibers of Example 5 were used without pretreatment with catalysis,
A hydroentangled nonwoven fabric was obtained in the same manner as in Example 5. The non-woven fabric was immersed in a standard concentration of MK220 (4 times that of Example 1) catalyst solution for 20 minutes, washed with water, and then immersed in an accelerator solution of 10% sulfuric acid for 15 minutes, washed with water and subjected to a catalyst pretreatment. Then, copper plating was performed in the same manner as in Example 5. When the sheet was cut and the voids appearing in its cross section were observed with a microscope, it was found that there was plating between the fibers that had become densely entangled by the hydroentangling treatment, despite the catalyst treatment pretreatment with a high concentration treatment liquid. The conductivity was also worse than in Example 5. In addition, crushing due to excessive catalyst occurs in the plating layer,
Moreover, it has been found that copper is deposited in the solution due to the removal of these excess catalysts during plating, and the life of the plating solution is significantly reduced.

[0056]

EFFECTS OF THE INVENTION By subjecting organic fibers to a catalytic treatment of electroless plating in advance, forming into a sheet, and then electroless plating, the catalyst is uniformly treated in the cross-sectional direction without using a high concentration catalyst solution. It is possible to obtain a plated sheet. As a result, it is possible to manufacture a plated sheet having excellent productivity, which enables immediate electroless plating of various metals on the same sheet. Further, after the sheet is formed, a hydroentangling treatment can be performed to produce a fluffy and highly flexible plated sheet.

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Claims (3)

[Claims] 1. A method for producing a plated non-woven fabric, which comprises using a fiber that has been subjected to a pretreatment for applying a catalyst by electroless plating, and forming the sheet into a post-plating treatment. 2. The method for producing a plated non-woven fabric according to claim 1, wherein after the pretreatment of the electroless plating on the fiber, a slurry prepared with the pretreatment liquid being used is formed into a sheet by a wet papermaking method. 3. The method for producing a plated non-woven fabric according to claim 1, which is formed into a sheet and then subjected to a three-dimensional entanglement treatment.