WO2016006614A1

WO2016006614A1 - Functional nonwoven used for molded resin body, molded resin body obtained using said nonwoven, and method for manufacturing said molded resin body

Info

Publication number: WO2016006614A1
Application number: PCT/JP2015/069565
Authority: WO
Inventors: 津田　統; 浩北原; 恵一郎和田; 高士見置
Original assignee: 株式会社巴川製紙所
Priority date: 2014-07-07
Filing date: 2015-07-07
Publication date: 2016-01-14
Also published as: JP6566753B2; JP2016027221A

Abstract

　The problem of the present invention is to provide a resin molding material in which functionality (e.g., imparting an electromagnetic wave shielding ability) and workability can be achieved simultaneously, in contrast to resin molding materials according to prior art. The present invention is a functional nonwoven used in a molded resin body, the functional nonwoven being obtained by causing a slurry obtained by adding 20-70 parts by mass of an organic fiber to 30-80 parts by mass of an electroconductive fiber to be made into a sheet.

Description

Functional nonwoven fabric used for resin molded body, resin molded body obtained using the same, and method for producing the same

The present invention relates to a nonwoven fabric or the like that can achieve both functional provision (for example, electromagnetic wave shielding provision) and good workability.

Resin molding material having some function, such as a shield material, by in-mold integral molding, insert mold integral molding, hot pressing, etc., in order to give functionality (including decoration) to the surface or surface layer of the resin molded body Conventionally, a method for integrating the resin and the resin has been proposed.

For example, in Patent Document 1, “a shield material formed in a sheet shape is inserted and installed between the split surfaces of the mold opening state of the molding die provided with a molding cavity and formed to be openable and closable through the split surfaces, A method for producing a molded article with a shield material, in which a thermoplastic resin material is injected and filled into the molding cavity after the mold is closed, and the shield material is transferred to one surface of the molded article. The shield material is fixed to the molded article by using a shield material formed in a mesh shape or a woven fabric shape with fibers made of a conductive material, and by allowing a part of the thermoplastic resin material to enter between the fibers. A method for producing a molded article with a shielding material characterized by the above.

Further, Patent Document 2 states that “when joining a thermoplastic laser-permeable resin member and a porous member, the laser-permeable resin member and the porous member are laminated, and the laser-permeable resin member side is laminated. The laser transmission is characterized in that the porous member is heated by irradiating a laser to melt the laser permeable resin member, impregnating the melted resin into the pores of the porous member, and then cooling and solidifying. A bonding method between the conductive resin member and the porous member "is disclosed.

JP-A-8-216182 JP 2005-297288 A

The object of the present invention is to provide a resin molding material capable of achieving both functionalization (for example, electromagnetic wave shielding) and good workability, in contrast to the resin molding material according to the conventional technology. And

As a result of diligent research to solve the above problems, the present inventors ensured the balance of the surface resistance value, tensile strength, and air permeability resistance of the nonwoven fabric, thereby imparting functionality (for example, imparting electromagnetic shielding properties) and It has been found that it is possible to provide a nonwoven fabric capable of achieving both good processability. In addition, the present inventors have conducted trial and error on various materials, compositions, shapes, manufacturing methods, etc. in order to ensure the balance of the surface resistance value, tensile strength, and air permeability resistance of the nonwoven fabric. Completed the invention.

The present invention (1) is a functional non-woven fabric used for a resin molded article obtained by making a slurry obtained by adding 20 to 70 parts by mass of organic fibers to 30 to 80 parts by mass of conductive fibers. is there.
In the present invention (2), the organic fiber includes a first thermoplastic resin fiber having a softening point of less than 140 ° C. and a second thermoplastic resin fiber having a softening point of 140 ° C. or higher. It is a functional nonwoven fabric of invention (1).
When the present invention (3) is based on the total mass of the first thermoplastic resin fiber and the second thermoplastic resin fiber, the ratio of the mass of the first thermoplastic resin fiber to the total mass Is a functional nonwoven fabric according to the invention (2), wherein 0.07 to 0.95.
In the present invention (4), the conductive fiber includes at least one of stainless fiber, carbon fiber, and copper fiber,
The functional nonwoven fabric according to any one of (1) to (3), wherein the organic fiber includes polyphenylene sulfide fiber.
The invention (5) is the functional nonwoven fabric of the invention (4), wherein the polyphenylene sulfide fiber contains 50 to 100% by mass of unstretched polyphenylene sulfide fiber based on the whole polyphenylene sulfide fiber.
The present invention (6) is the functional nonwoven fabric according to any one of the inventions (1) to (5), which is used when a resin molded product is produced by injection molding.
The present invention (7) is characterized in that the functional nonwoven fabric used in the resin molded body according to any one of the inventions (1) to (6) is integrated with the surface layer or inside of the thermoplastic resin. It is a resin molding.
In the present invention (8), the thermoplastic resin is at least one selected from the group consisting of a polyarylene sulfide resin, a polybutylene terephthalate resin, a polyacetal resin, and a liquid crystal polymer resin. It is.
The present invention (9) is a method for producing a resin molded body comprising a step of integrating the functional nonwoven fabric according to any one of the inventions (1) to (5) into the surface layer or inside of a thermoplastic resin, In the method for producing a resin molded body, the integrating step is one of injection molding, laser welding, high-frequency induction heating welding, and hot pressing.

When the nonwoven fabric according to the present invention is used, in contrast to conventional resin molding materials, it provides functionality (for example, imparting electromagnetic shielding properties) and good workability (for example, suppression characteristics such as gas burning and weld lines). It is possible to achieve both. Furthermore, the resin molded body obtained using the nonwoven fabric according to the present invention also has an advantage that it is difficult to detach or peel from the surface or surface layer of the resin molded body.

The present invention is a functional non-woven fabric used for a resin molded article obtained by making a slurry obtained by adding 20 to 70 parts by mass of organic fibers to 30 to 80 parts by mass of conductive fibers. Hereinafter, the production method of the functional nonwoven fabric according to the present invention, the structure and physical properties of the functional nonwoven fabric, the use of the functional nonwoven fabric, and the like will be described in order.

≪Method for producing functional nonwoven fabric≫
<Raw material>
(Conductive fiber)
Examples of the conductive fiber according to the present invention include carbon fibers, metal-coated carbon fibers, stainless fibers, aluminum fibers, copper fibers, brass fibers, and other inorganic fibers, and metal-coated glass fibers. Among these, it is understood that carbon fiber, copper fiber, or stainless steel fiber is particularly excellent in degassing characteristics. This is because these fibers are highly rigid, so that the gas on the resin side can be discharged almost certainly through the skeleton of the fibers during processing. In addition, these fibers are preferable from the viewpoint of excellent electromagnetic shielding properties. Two or more of these can be used in combination. Here, “conductive” as used in the present specification and claims means that the volume resistivity is less than 100 Ωcm. The term “functionality” as used in the present specification and claims refers to the ability to impart shielding properties and thermal conductivity.

Specific examples of carbon fibers include, for example, trading cards manufactured by Toray Industries, Inc., besfite filaments manufactured by Toho Tenax Co., Ltd., and pyrofils manufactured by Mitsubishi Rayon Co., Ltd. Specific examples of stainless fibers include For example, stainless steel fibers manufactured by Nippon Seisen Co., Ltd. or Bekaert Co., Ltd. can be mentioned, and specific examples of copper fibers include C1100 manufactured by Nijigi Co., Ltd.

In addition, these conductive fibers may be surface-treated with a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, or the like in order to improve the adhesion with the resin molded body component.

The average fiber length of the conductive fibers is preferably in the range of 1 mm to 10 mm, more preferably in the range of 3 mm to 6 mm. When the average fiber length is within this range, it is easier to balance the electromagnetic shielding properties of the resin molded body in addition to the ease of manufacturing the nonwoven fabric. In addition, "average fiber length" in this specification including the organic fiber and PPS fiber which are demonstrated below is a value which measured 20 values with the microscope and averaged the measured value.

The fiber diameter of the conductive fibers is preferably in the range of an average fiber diameter of 1 to 20 μm. When the average fiber diameter is within this range, it is easier to balance the moldability of the resin molded body and the electromagnetic wave shielding property in addition to the ease of manufacturing the nonwoven fabric. In addition, “average fiber diameter” in the present specification calculates a cross-sectional area based on a cross-section of a fiber imaged with a microscope (for example, with known software), and calculates a diameter of a circle having the same area as the cross-sectional area. It is the average value of the area diameter derived by this (average value of 20 fibers).

(Organic fiber)
Examples of the organic fiber according to the present invention include polyamide fiber, polyester fiber, polyethylene terephthalate fiber (hereinafter also referred to as PET or PET fiber), acrylic fiber, polyolefin fiber, aramid fiber, polyethylene naphthalate fiber, polybutylene terephthalate fiber, poly Examples include arylene sulfide resin {for example, polyphenylene sulfide fiber (hereinafter also referred to as PPS fiber)}, polyacetal fiber, liquid crystal polymer fiber, polyimide fiber, cotton, hemp and the like. These can be used alone or in combination of two or more. Moreover, when heat resistance is required, a PPS fiber can be used conveniently. Furthermore, modified polyethylene terephthalate fibers can be suitably used from the viewpoint of sheet shape retention after papermaking and drying. Here, the “modified polyethylene terephthalate” means an ethylene glycol unit and a terephthalic acid unit as main structural units, an isophthalic acid unit, a phthalic acid unit, a 2,3-naphthalene dicarboxylic acid unit, and a 5-alkali metal sulfoisophthalic acid unit. Aromatic dicarboxylic acid units such as adipic acid units, azelaic acid units, sebacic acid units and other aliphatic dicarboxylic acid units; diethylene glycol units, propylene glycol units, 1,4-butanediol units and other diol units The ethylene terephthalate polymer contained at 25 mol% or less), and among them, an amorphous ethylene terephthalate polymer is particularly preferred. These organic fibers may be surface-treated with a silane coupling agent, a titanate coupling agent, an aluminate coupling agent or the like in order to improve the adhesion with the resin molded body component. Moreover, when selecting a PPS fiber as the organic fiber, a stretched or unstretched PPS fiber can be used. From the viewpoint of ease of thermal fusion and dimensional stability during heating, the stretched or unstretched PPS fiber can be used. It is preferable to mainly use PPS fibers. In particular, it is particularly preferable that the unstretched PPS resin is contained in an amount of 50 to 100% by mass of the entire PPS fiber. Since the unstretched PPS fiber has not progressed in crystallization, it tends to be melted at the time of heat calendering described later or during resin molding, and tends to ensure adhesion with the resin for the molded body. The unstretched or stretched PPS fiber may be beaten to adjust the average fiber length or make it fluffy. Thereby, it is possible to obtain effects such as dense and entangled fibers and securing strength by catching. As a beating process method, it can carry out suitably by SDR, DDR, a beater etc. which are generally used in a papermaking process. As a substitute for the PPS fiber subjected to the beating treatment, a PPS resin powder that has been made into a fiber by beating treatment can also be used. From the viewpoint of cost, it is advantageous to use the PPS resin powder rather than the PPS fiber, but it is difficult to make the resin powder as it is in the wet papermaking process. Therefore, it is possible to reduce the particle size and fluff of the PPS resin powder by beating treatment, and to obtain a nonwoven fabric by being caught between resin powders and entangled or caught with PPS fibers. SDR, DDR, and a beater can be used for the beating process method of PPS resin powder similarly to a fiber. In addition, it is possible to carry out processing by various machines that perform dry mixing, grinding, pulverization, and the like.

Here, the organic fiber includes a first thermoplastic resin fiber having a first softening point and a second thermoplastic resin fiber having a softening point higher than the first softening point. Is preferred. Use of a combination of thermoplastic resin fibers having different softening points can provide functionality (for example, imparting electromagnetic shielding properties) and good workability (for example, suppression characteristics such as gas burning and weld lines). It is more convenient to achieve both. In particular, the organic fiber may include a first thermoplastic resin fiber (binding fiber) having a softening point of less than 140 ° C. and a second thermoplastic resin fiber having a softening point of 140 ° C. or higher. Is preferred. The first thermoplastic resin fiber melts at the drying temperature at the time of papermaking, thereby serving to fuse the metal fiber and the second thermoplastic resin fiber. In addition, "140 degreeC" here is a drying temperature at the time of general papermaking. That is, in other words, it is particularly preferable to select the first and second thermoplastic resin fibers such that the softening points of the first and second thermoplastic resin fibers straddle the drying temperature.

The “softening point” in the present specification and claims is a value measured according to the following measurement method.
(Measurement method of softening point)
Using 3 g of organic fibers, the fibers are entangled to prepare an approximately 8 × 8 cm rectangular body having a substantially uniform thickness. Then, the substantially rectangular body is sandwiched between two metal plates, and the substantially rectangular body is heated at a predetermined temperature for 2 minutes in a pressurized state of 100 g / cm ² while maintaining the state. Then, it is cooled and lifted, and it is confirmed whether or not it is bound into a sheet. At this time, when 90% by mass or more is lifted when it is lifted from one part (that is, when the remaining amount on the metal plate is less than 10% by mass), it is determined as “binding in a sheet shape”. The lowest temperature at which such a state occurs is defined as the softening point (average of 100 times).

Further, at least one of the organic fibers is preferably the same type as the resin for the resin molded body from the viewpoint of improving processability.

The average fiber length of the organic fiber according to the present invention is preferably in the range of 1 mm to 10 mm, more preferably 3 mm to 6 mm. If the average fiber length is within the above range, the moldability of the resin molded body can be further improved in addition to the ease of producing the nonwoven fabric. The average fiber diameter of the organic fibers is preferably in the range of 1 μm to 30 μm. When the average fiber diameter is within the above range, the entanglement of the added fibers is easy to proceed, and a supple nonwoven fabric can be obtained, so that the processing characteristics when integrated into the resin molded body are excellent.

(Other ingredients)
In producing the nonwoven fabric according to the present invention, it is essential to use conductive fibers and organic fibers as raw materials, but other components may be added depending on the application. As other components, for example, glass fiber, magnesium silicate fiber, or inorganic fiber such as glass wool, slag wool, rock wool, etc., for example, calcium carbonate, cinnabar sand, microsilica, mica, hydroxide Various powders such as aluminum can be supported on the functional nonwoven fabric of the present invention.

(Mechanism of action)
As mentioned above, when manufacturing the nonwoven fabric which concerns on this invention, electroconductive fiber and organic fiber are made into an essential raw material. Although these are essential components, and the mechanism of action that can achieve the effects of the present invention by further limiting the blending amount is not clear, (Reason 1) When the resin melted by heat impregnates the inside of the nonwoven fabric, the affinity is In addition to being easy to impregnate in the first place due to the presence of high organic fibers, (Reason 2) When organic fibers are also melted by heat, impregnation is further promoted, and (Reason 3) conductive fibers that are not melted by heat Is present as a skeleton, it is presumed that the gas on the resin side can be reliably discharged through the skeleton when pressure is applied.

<Combination>
(Conductive fiber / organic fiber)
In the production of the nonwoven fabric according to the present invention, the blending amount of the conductive fiber is 30 to 80 parts by mass, preferably 40 to 80 parts by mass with respect to 20 to 70 parts by mass of the organic fiber. By blending the conductive fiber and the organic fiber in the range, an appropriate balance of the surface resistance value, the tensile strength, and the air resistance value can be ensured. By ensuring the balance, it is possible to impart high electromagnetic shielding properties and the like to the resin molded body as compared with conventional resin molding materials (that is, having high conductivity), and at the time of manufacturing the resin molded body It is possible to exhibit extremely excellent workability (for example, suppression characteristics such as gas burning and weld lines).

(First thermoplastic resin fiber / second thermoplastic resin fiber)
As described above, the organic fiber that is one raw material of the nonwoven fabric according to the present invention has a first thermoplastic resin fiber (binding fiber) whose softening point is the first temperature (preferably less than 140 ° C.); And a second thermoplastic resin fiber having a second softening point higher than the first temperature (preferably 140 ° C. or higher). Here, when the total mass of the first thermoplastic resin fiber and the second thermoplastic resin fiber is used as a reference, the ratio of the mass of the first thermoplastic resin fiber to the total mass is 0. 0.07 to 0.95 is preferable, 0.10 to 0.93 is more preferable, and 0.15 to 0.50 is still more preferable.

<Process>
As described above, the nonwoven fabric according to the present invention is obtained by making a slurry (wet paper making method) by adding 20 to 70 parts by mass of organic fibers to 30 to 80 parts by mass of conductive fibers. More specifically, the method for producing the functional nonwoven fabric by wet papermaking method is a papermaking slurry formed by adding one or more kinds of conductive fibers and organic fibers and other raw materials as required. When the sheet is formed by the wet papermaking method, it includes a fiber entanglement process step in which the conductive fibers and the organic fibers forming the sheet containing moisture on the net are entangled with each other. Hereinafter, each process is explained in full detail.

(Paper making process)
For the paper making process, various methods such as long net paper making, circular net paper making, inclined wire paper making and the like can be adopted as necessary. In addition, when manufacturing a slurry containing long-fiber conductive fibers and / or organic fibers, the dispersibility of these fibers in water may be deteriorated, so that polyvinylpyrrolidone, polyvinyl alcohol, and carboxymethylcellulose having a thickening action A small amount of an aqueous polymer solution such as (CMC) may be added.

(Fiber entanglement process)
As the fiber entanglement treatment step, for example, a fiber entanglement treatment step of injecting a high-pressure jet water stream onto the functional nonwoven fabric surface after paper making is preferably employed. The fibers can be entangled over the entire sheet by the technique (for example, a technique in which a plurality of nozzles are arranged in a direction orthogonal to the flow direction of the sheet and a high-pressure jet water stream is simultaneously ejected from the nozzles). It is possible. That is, for example, by injecting a high-pressure jet water stream in the Z-axis direction of the sheet into a sheet composed of fibers etc. that irregularly intersect the plane direction by wet papermaking, each of the portions where the high-pressure jet water stream is injected The fibers are oriented in the Z-axis direction. Each fiber oriented in the Z-axis direction is entangled between fibers irregularly oriented in the plane direction, and each fiber is entangled three-dimensionally with each other, that is, the physical strength can be obtained by entanglement. is there.

(Dryer process)
In the dryer process (drying process), the organic fiber constituting the functional nonwoven fabric is dried by heating at a temperature equal to or higher than the softening point of at least one kind (first thermoplastic resin fiber) (removal of a dispersion medium such as water). It is preferable to do. As a result, an adhesive effect is produced between fibers heated above the softening point, or between fibers heated above the softening point and other fibers (for example, metal fibers). It is possible to increase the pressure resistance of the functional nonwoven fabric when the is injected.

(Thermal calendar process)
A thermal calendar can be further applied after the above step. By processing the functional non-woven fabric with heat and pressure, for example, the organic fibers that have not been fused in the dryer step are fused, exhibit further adhesion effects, and the distance between the conductive fibers by pressurization By shrinking, the electromagnetic wave shielding property of the functional nonwoven fabric can be further enhanced.

(Baking process)
Furthermore, after the above-described wet papermaking step, the obtained functional nonwoven fabric may be configured to include a sintering step in which the functional nonwoven fabric is sintered in a vacuum or in a non-oxidizing atmosphere at a temperature not higher than the melting point of the conductive fibers. That is, if the sintering process is performed after the wet papermaking process described above, the fixing of the conductive fiber entangled portion is promoted, and therefore the electromagnetic wave shielding property and heat of the functional nonwoven fabric used in the resin molded body of the present invention. There is an advantage that the conductivity is easily improved.

≪Physical properties and structure of functional nonwoven fabric≫
(Air permeability resistance)
The air resistance of the functional nonwoven fabric used in the resin molded product of the present invention is preferably 10 sec or less, and more preferably 3 sec or less. Within this range, it is possible to provide a nonwoven fabric that can exhibit better processability during the production of a resin molded body. Further, the air resistance is not particularly limited as long as the strength required for the functional nonwoven fabric is maintained. The air resistance is a value measured according to JIS P8117.

(Basis weight)
The basis weight of the functional nonwoven fabric used in the resin molded body of the present invention is preferably 50 g / m ² to 500 g / m ² , more preferably 90 g / m ² to 400 g / m ² . Provided a nonwoven fabric capable of imparting higher electromagnetic wave shielding properties and the like to the resulting resin molded article and exhibiting superior processability during the production of the resin molded article within the range. It becomes possible.

(density)
Density functional nonwoven used for resin molding of the present invention ^is preferably 1.20g / cm 3 ~ 1.90g / cm 3. Provided a nonwoven fabric capable of imparting higher electromagnetic wave shielding properties and the like to the resulting resin molded article and exhibiting superior processability during the production of the resin molded article within the range. It becomes possible.

(thickness)
The thickness of the functional nonwoven fabric used in the resin molded product of the present invention is preferably 50 μm to 320 μm, and more preferably 50 μm to 100 μm. Within this range, it is possible to provide a nonwoven fabric that can exhibit better processability during the production of a resin molded body.

The tensile strength of the functional nonwoven fabric used in the resin molded body of the present invention is preferably 10N or more, and more preferably 25N or more. Within this range, it is possible to provide a nonwoven fabric that can exhibit better processability during the production of a resin molded body. The tensile strength and tensile elongation were measured according to JIS P8113, with the sheet width in the tensile direction being 15 mm.

(Construction)
The functional nonwoven fabric is presumed to exist in a state in which conductive fibers and organic fibers are appropriately entangled with each other and have micropores. Thereby, it is understood that the functional nonwoven fabric has an appropriate surface resistance value, an appropriate tensile strength, and an appropriate air resistance. For this reason, while being able to provide high electromagnetic shielding property etc. to a resin molding, it becomes possible to exhibit the extremely outstanding workability at the time of manufacture of a resin molding.

≪Use of functional nonwoven fabric≫
(Use target)
The resin molded body of the present invention is obtained by bonding the functional nonwoven fabric of the present invention to a thermoplastic resin by the method described later. Here, the thermoplastic resin to be bonded to the functional nonwoven fabric of the present invention (that is, the thermoplastic resin integrated with the functional nonwoven fabric) is not particularly limited. Examples of the thermoplastic resin include polyamide resin, polyester resin, polyethylene terephthalate resin (hereinafter also referred to as PET resin), acrylic resin, polyolefin resin, aramid resin, polyethylene naphthalate resin, polybutylene terephthalate resin, and polyarylene sulfide resin. {For example, polyphenylene sulfide resin (hereinafter also referred to as PPS resin)}, polyacetal resin, liquid crystal polymer resin, polyimide resin, and the like. These can be used alone or in combination of two or more. Among these, PPS resin, polybutylene terephthalate resin, polyacetal resin, and liquid crystal polymer resin can be suitably used from the viewpoint of heat resistance. The thermoplastic resin may contain, as necessary, other components such as an inorganic filler, a lubricant, carbon black, a nucleating agent, a flame retardant, a flame retardant aid, an antioxidant, a metal deactivator, a UV absorber, It may contain polymers such as stabilizers, plasticizers, pigments, dyes, colorants, antistatic agents, foaming agents, other resins, and additives.

(how to use)
The method for producing the resin molded body according to the present invention, that is, the method for integrating the functional nonwoven fabric and the thermoplastic resin used in the resin molded body of the present invention is not particularly limited, and a known method is adopted. can do. For example, it can be produced by in-mold integral molding by injection molding, insert mold integral molding, laser welding, high-frequency induction heating welding, hot pressing, or the like. However, among these, the functional nonwoven fabric according to the present invention is particularly suitable for injection molding. Although a technique for impregnating a molten resin into a nonwoven fabric is known, many are techniques for heating and pressing a sheet-like resin. In this case, no gas remains on the sheet-shaped resin side (because almost all the sheet-shaped resin enters the functional nonwoven fabric). On the other hand, in the injection molding, a part of the molten resin stays in the functional sheet, and a large amount of the molten resin does not enter the functional sheet. In this case, the gas remains on the molten resin side (near the interface between the molten resin and the functional nonwoven fabric), resulting in problems such as processing defects. Even in such a case, the functional nonwoven fabric according to the present invention has a function of discharging the gas on the molten resin side through the functional nonwoven fabric, and thus is particularly suitable for injection molding as described above. .

Hereinafter, the functional nonwoven fabric used in the resin molded body of the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1
Stainless fiber with an average fiber length of 4 mm, an average fiber diameter of 8 μm, an average fiber length of 5 mm, an average fiber diameter of 22 μm, an unstretched polyphenylene sulfide fiber with a softening point of 200 ° C., an average fiber length of 3 mm, an average fiber diameter of 10 μm, and an isophthalate with a softening point of 120 ° C. The acid-modified polyethylene terephthalate fiber was stirred for 5 minutes using an agitator with the following composition and dispersed in water.
Stainless steel fiber: 45 parts by mass Unstretched polyphenylene sulfide fiber: 45 parts by mass Isophthalic acid-modified polyethylene terephthalate fiber: 10 parts by mass Water 100 parts by mass Then, the above fiber dispersion 2L was poured into a square handmaking machine and simply dehydrated. Thereafter, moisture was further removed using a Yankee dryer heated to 140 ° C., and fibers constituting the nonwoven fabric were bound together by melting isophthalic acid-modified polyethylene terephthalate fibers. The nonwoven fabric thus formed into a sheet is heated to 210 ° C. and passed through a heat calender pressurized to ² kg / cm ² , and further heated and compressed to promote binding. The functional nonwoven used was obtained.

Integration by injection molding Under the following conditions, the functional nonwoven fabric and the thermoplastic resin were integrated by injection molding to obtain a resin molded body of the present invention.
Thermoplastic resin: polyphenylene sulfide resin composition (manufactured by Polyplastics Co., Ltd., “Durafide (registered trademark) 1140A7 (HF2000)”)
Injection molding machine: SE100D, manufactured by Sumitomo Heavy Industries, Ltd.
Molded body shape: flat plate having a length of 80 mm, a width of 80 mm, and a thickness of 4 mm (one side surface layer of the flat plate and the nonwoven fabric were integrated)
Molding conditions: cylinder temperature: 320 ° C., mold temperature: 150 ° C., injection speed: 10 mm / sec, holding pressure: 50 MPa, holding pressure time: 15 sec, cooling time: 15 sec

Integration by Laser Welding Under the following conditions, the functional nonwoven fabric was sandwiched between thermoplastic resin plates and integrated by laser welding to obtain a resin molded body of the present invention.
Laser welding equipment: Laser welding system NOVOLAS C (manufactured by Leister Technologies)
Thermoplastic resin plate: Polyphenylene sulfide resin composition (manufactured by Polyplastics Co., Ltd., "Durafide (registered trademark) 0220A9 (HF2000)", by injection molding machine (Sumitomo Heavy Industries, Ltd., SE100D) Two test pieces (flat plates) having a cylinder temperature of 320 ° C. and a mold temperature of 150 ° C. having a length of 80 mm, a width of 80 mm, and a thickness of 1 mm were produced.
Welding conditions: scan speed: 10 mm / sec, beam diameter: 0.6 mm, current 30 A; a nonwoven fabric was sandwiched between two flat plates, and laser was irradiated from the upper part of the flat plates under the above-mentioned welding conditions for welding.

Integration by hot pressing Under the following conditions, the functional nonwoven fabric and the thermoplastic resin plate were integrated by hot pressing to obtain a resin molded body of the present invention.
Hot press machine: Mini test press MP-SNH (manufactured by Toyo Seiki Seisakusho)
Thermoplastic resin plate: Polyplastics Co., Ltd., “Durafide (registered trademark) 0220A9 (HD9100)”, injection molding machine (Sumitomo Heavy Industries, Ltd., SE100D), cylinder temperature 320 ° C., gold One test piece (flat plate) having a mold temperature of 150 ° C. and a length of 50 mm, a width of 50 mm, and a thickness of 3 mm was produced.
Integration conditions: temperature: 300 ° C., pressurization: 5 MPa, pressurization time: 30 sec; a nonwoven fabric was placed on a flat plate and pressed to be integrated.

<< Example 2 >>
A functional nonwoven fabric used for the resin molded body of Example 2 was obtained in the same manner as in Example 1 except that 30 parts by mass of stainless steel fiber and 60 parts by mass of unstretched polyphenylene sulfide fiber were obtained. Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention. In addition, integration by injection molding was implemented in the following examples including this example.

Example 3
A functional nonwoven fabric used for the resin molded body of Example 3 was obtained in the same manner as in Example 1 except that 80 parts by mass of stainless steel fibers and 10 parts by mass of unstretched polyphenylene sulfide fibers were obtained. Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

Example 4
A functional nonwoven fabric used for the resin molded body of Example 4 was obtained in the same manner as in Example 1 except that the fiber dispersion was 10 L. Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

Example 5
A functional nonwoven fabric used for the resin molded body of Example 5 was obtained in the same manner as in Example 1 except that stainless steel fibers having an average fiber length of 1 mm and an average fiber diameter of 8 μm were used. Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

Example 6
A functional nonwoven fabric used for the resin molded body of Example 6 was obtained in the same manner as in Example 1 except that stainless steel fibers having an average fiber length of 10 mm and an average fiber diameter of 8 μm were used. Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

Example 7
A functional nonwoven fabric used for the resin molded body of Example 7 is obtained in the same manner as in Example 1 except that unstretched polyphenylene sulfide fibers having an average fiber length of 1 mm, an average fiber diameter of 22 μm, and a softening point of 200 ° C. are used. It was. Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

Example 8
Used in the resin molded body of Example 8 in the same manner as in Example 1 except that polyethylene terephthalate fiber having an average fiber length of 5 mm, an average fiber diameter of 7 μm, and a softening point of 225 ° C. was used instead of unstretched polyphenylene sulfide fiber. A functional nonwoven fabric was obtained. Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

Example 9
A functional nonwoven fabric used for the resin molding of Example 9 was obtained in the same manner as in Example 1 except that 5 parts by mass of unstretched polyphenylene sulfide fiber and 50 parts by mass of isophthalic acid-modified polyethylene terephthalate fiber were obtained. . Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

Example 10
A functional nonwoven fabric used for the resin molding of Example 10 was obtained in the same manner as in Example 1 except that 25 parts by mass of unstretched polyphenylene sulfide fiber and 30 parts by mass of isophthalic acid-modified polyethylene terephthalate fiber were obtained. . Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

≪Comparative example 1≫
A 21 μm thick copper foil was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain a resin molded body of Comparative Example 1.

≪Comparative example 2≫
A functional nonwoven fabric used for the resin molded article of Comparative Example 2 was obtained in the same manner as in Example 1 except that the stainless fiber was not added and that 90 parts by mass of unstretched polyphenylene sulfide fiber was used. Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

«Comparative Example 3»
A functional nonwoven fabric used for the resin molding of Comparative Example 3 is obtained in the same manner as in Example 1 except that 100 parts by mass of stainless steel fiber, unstretched polyphenylene sulfide fiber, and isophthalic acid-modified polyethylene terephthalate fiber are not added. It was. Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

<< Comparative Example 4 >>
A functional nonwoven fabric used for the resin molding of Comparative Example 4 was obtained in the same manner as in Example 1 except that 85 parts by mass of stainless steel fibers and 5 parts by mass of unstretched polyphenylene sulfide fibers were obtained. Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

<< Comparative Example 5 >>
A functional nonwoven fabric used for the resin molding of Comparative Example 5 was obtained in the same manner as in Example 1 except that 20 parts by mass of stainless steel fiber and 70 parts by mass of unstretched polyphenylene sulfide fiber were obtained. Furthermore, the functional nonwoven fabric was integrated with the surface of the polyphenylene sulfide resin molded body by in-mold injection molding to obtain the resin molded body of the present invention.

Table 1 shows an outline of the constitution of the functional nonwoven fabric produced in Examples 1 to 10 and Comparative Examples 1 to 5.

The physical properties of the functional nonwoven fabrics and copper foils of Examples 1 to 10 and Comparative Examples 1 to 5 are shown below.

Measurement of air resistance The air resistance was measured for the functional nonwoven fabrics produced in the examples and comparative examples. The air resistance was measured according to JIS P8117. The evaluation was carried out with a case where the air permeability resistance was less than 3 seconds, a case where it was 3-10 seconds, a case where it was more than 10 seconds, and a case where it was more than 10 seconds.

Measurement of Tensile Strength and Tensile Elongation The tensile strength and the tensile elongation were measured for the functional nonwoven fabrics produced in Examples and Comparative Examples. The tensile strength and tensile elongation were measured according to JIS P8113, with the sheet width in the tensile direction being 15 mm. The evaluation was carried out with a case where the tensile strength was 25N or more, ◎, a case where the tensile strength was less than 8 to 25N, and a case where the tensile strength was less than 8N.

Measurement of surface resistivity The surface resistivity was measured for the functional nonwoven fabrics produced in Examples and Comparative Examples. Using Loresta AX MCP-T370 (manufactured by Mitsubishi Analytech Co., Ltd.), any five locations of the functional nonwoven fabrics produced in the examples and comparative examples were tested by the resistivity test method based on the 4-probe method of JIS K7194 conductive plastic. The average value was measured as the surface resistance value. The lower the surface resistance, the more easily the electromagnetic wave shielding effect is expressed. The case where the surface resistance value was 2.5Ω / □ or less was evaluated as “◎”, the case where the surface resistance value was over 2.5 to 5.0Ω / □ was evaluated as “◯”, and the case where the surface resistance value was above 5.0Ω / □ was evaluated as “X”.

Measurement and Results of Electromagnetic Shielding Using U3741 SPECTRUM ANALYZER (manufactured by Advantest), the electromagnetic shielding properties of the resin moldings produced in Examples and Comparative Examples were measured by the Advantest method. As a result, the electromagnetic wave shielding effects of the resin moldings of Examples 1 to 10, Comparative Example 1 and Comparative Example 4 were 30 dBm to 60 dBm. Moreover, the electromagnetic wave shielding effect of the resin molding of Comparative Example 5 was about 20 dBm. In contrast, Comparative Example 2 had almost no electromagnetic shielding effect. Considering that the effective radiated power is attenuated by 99.9% due to the shielding effect of 30 dBm, a sufficient electromagnetic shielding effect can be expected if the electromagnetic shielding effect in the frequency range of 10 MHz to 1 GHz is 30 dBm or more.

Evaluation results Examples 1 to 10 had an air permeability resistance of 10 sec or less and an electromagnetic wave shielding effect of 30 to 60 dBm, and the functional nonwoven fabric of the present invention was not easily peeled from the resin molded body. In all of the examples, no processing defects (for example, gas burns or weld lines) to the extent of quality problems were found. On the other hand, since Comparative Example 1 is obtained by welding a copper foil to a resin molded body, it is restricted by a mold design for degassing and cannot be expected to have an anchor effect of a molding resin like a nonwoven fabric. For this reason, the copper foil tends to be peeled off particularly from the end portion. Moreover, since the comparative example 2 did not contain the conductive fiber, the electromagnetic wave shielding effect was not acquired and the air permeability resistance was also high. In Comparative Example 3, the nonwoven fabric collapsed during removal from the dryer process, and the sheet shape could not be maintained. In Comparative Example 4, the surface resistivity was good, but the nonwoven fabric broke during in-mold injection molding, and the electromagnetic shielding properties could not be measured. In Comparative Example 5, the electromagnetic wave shielding effect was as low as 20 dBm. In addition, as shown in Example 1, it was shown that any processing method such as injection molding, laser welding, and hot pressing can be applied.

Claims

Non-woven fabric used for resin moldings, obtained by making a slurry made by adding 20 to 70 parts by mass of organic fibers to 30 to 80 parts by mass of conductive fibers.
The nonwoven fabric according to claim 1, wherein the organic fiber includes a first thermoplastic resin fiber having a softening point of less than 140 ° C and a second thermoplastic resin fiber having a softening point of 140 ° C or higher.
When the total mass of the first thermoplastic resin fiber and the second thermoplastic resin fiber is used as a reference, the ratio of the mass of the first thermoplastic resin fiber to the total mass is 0.07 to 0. The nonwoven fabric of Claim 2 which is .95.
The conductive fiber includes at least one of stainless fiber, carbon fiber, and copper fiber,
The nonwoven fabric according to any one of claims 1 to 3, wherein the organic fibers include polyphenylene sulfide fibers.
The nonwoven fabric according to claim 4, wherein the polyphenylene sulfide fiber contains 50 to 100% by mass of unstretched polyphenylene sulfide fiber based on the whole polyphenylene sulfide fiber.
The nonwoven fabric according to any one of claims 1 to 5, which is used when a resin molded body is produced by injection molding.
A resin molded body comprising a nonwoven fabric used in the resin molded body according to any one of claims 1 to 6 integrated with a surface layer or inside of a thermoplastic resin.
The resin molded article according to claim 7, wherein the thermoplastic resin is at least one selected from the group consisting of a polyarylene sulfide resin, a polybutylene terephthalate resin, a polyacetal resin, and a liquid crystal polymer resin.
A method for producing a resin molded body comprising a step of integrating the nonwoven fabric according to any one of claims 1 to 5 into a surface layer or inside of a thermoplastic resin, wherein the step of integrating comprises injection molding, A method for producing a resin molded body, which is one of laser welding, high-frequency induction heating welding, and hot pressing.