JPH11199707A - Different diametral metal fibers-containing resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin compsn. which has excellent fiber processability, electromagnetic shielding effect, and external appearance and is especially useful as an electromagnetic shielding resin compsn., by using such a thin fiber as is not easily snappable on fiber processing. SOLUTION: A thermoplastic resin compsn. comprises 1-70 wt.% of (A) a metal fiber with an equivalent circle dia. less than 50 μm, 0.001-30 wt.% of (B) a metal fiber with an equivalent circle dia. thicker by 5 μm or more than that of (A), and 98.999-29 wt.% of (C) a thermoplastic resin. A metal fiber-contg. master pellet comprises 1-90 wt.% of (A) a metal fiber with an equivalent circle dia. less than 50 μm, 0.001-30 wt.% of (B) a metal fiber with an equivalent circle dia. thicker by 5 μm or more than that of (A), and 98.999-9.999 wt.% of (C) a thermoplastic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding material having electrical conductivity, particularly to an electromagnetic wave shielding material.

[0002]

2. Description of the Related Art Electric circuits and ICs are used in various electric devices, but may malfunction due to electromagnetic waves generated from outside and inside. In order to prevent this, the generation of electromagnetic waves has been reduced by changing the circuit design, but there is a limit, and they are covered with a material having an electromagnetic wave shielding effect. For these materials, a method of forming a conductive film on a resin molded product by plating, painting, thermal spraying, or the like is employed, but a separate step is required and the cost is high.

[0003] Therefore, it has been practiced to give the resin itself shielding properties. As a method of imparting shielding properties to a resin, a method of kneading metal fibers, foils, particles, or carbon black, carbon fiber, ferrite, barium titanate, or the like is known. Among them, the method using metal fibers is most effective. The wire drawing method is known as a method for producing thin metal fibers industrially,
Although it is possible to produce high-strength, for example, stainless steel fibers, it has been difficult to produce relatively low-strength fibers such as copper and brass.

For example, the coil material cutting method is an excellent method for producing metal fibers. However, when processing the resulting fiber, for example, when coating with a resin or performing surface treatment of the fiber, processing using only fine fibers is not sufficient. It had an improvement that it was cut off on the way and markedly reduced productivity.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to produce a thin fiber which is not easily cut at the time of fiber processing, and to use the fiber to produce a resin composition having excellent fiber processing properties, electromagnetic wave shielding effect and surface appearance. To get.

[0006]

Means for Solving the Problems The present inventors have obtained a metal fiber which is difficult to break (fiber workability) at the time of metal fiber processing by coexisting thick metal fiber, and by combining this with a resin or the like. The present inventors have found that a conductive resin composition having excellent electromagnetic wave shielding effect and surface appearance can be obtained, and have accomplished the present invention.

That is, the present invention is as follows. 1) (A) 1 to 70% by weight of a metal fiber having a circle-converted diameter of less than 50 μm, (B) 0.001 to 30% by weight of a metal fiber having a circular-converted diameter of 5 μm or more than (A), and (C) a thermoplastic resin A thermoplastic resin composition comprising 98.999 to 29% by weight. 2) (A) 1 to 70% by weight of a metal fiber having a circle-converted diameter of less than 50 μm, (B) 0.001 to 30% by weight of a metal fiber having a circular-converted diameter of 5 μm or more than (A), and (C) a thermoplastic resin An electromagnetic wave shielding resin composition comprising 98.999 to 29% by weight.

3) (A) 1 to 90% by weight of a metal fiber having a circle-converted diameter of less than 50 μm, (B) a circle-converted diameter of 5 μm from (A)
0.001 to 30% by weight of the above thick metal fiber, and (C)
A metal fiber-containing master pellet comprising 98.999 to 9.999% by weight of a thermoplastic resin. Hereinafter, the present invention will be described in detail.

The metal fiber (A) used in the present invention,
As the metal species of (B), materials of materials such as stainless steel, brass, copper, aluminum, iron, gold, silver, nickel, and titanium can be used. Among these, metals having particularly remarkable effects are metals having a low tensile strength, and specific examples include brass,
Examples include metals such as copper, aluminum, gold, silver, tin, lead, zinc, and magnesium, alloys of a combination of two or more of these, or alloys containing these as a main component, and compounds of these with phosphorus. Among them, brass,
Copper and aluminum are preferred.

The cross-sectional shape of the metal fiber (A) used in the present invention is not particularly limited, but the average diameter (circle-converted diameter) of a circle having the same cross-sectional area as the circle is less than 50 μm in (A). Preferably 40 μm or less, more preferably 30 μm
μm or less. However, if it is, for example, 1 μm or less, or too thin, it is difficult to produce fibers. If it is 50 μm or more, the aspect ratio of the fiber becomes small, and it is necessary to add a large amount of the fiber in order to obtain a sufficient shielding effect.

As the fiber bundle, the number of the fibers is 10 to
100,000 bundles are preferred, more preferably 50 to 30,000, and still more preferably 100 to 300.
It is desirable that the bundle is zero. However, in this fiber bundle, the number of fibers (B), which will be described in detail later, is one or more, and the upper limit is 50, which is the total number of fibers (A) and (B).
%, Preferably 30% or less, most preferably 20% or less. (B) When the number of fibers increases, the effect of the fine fibers decreases, which is not so preferable.

The metal fiber (A) can be obtained by a coil material cutting method or the like. The coil material cutting method is a method in which a metal foil is mounted in a coil material shape on a metal fiber manufacturing apparatus having a structure and a function similar to those of a lathe, and the end surface thereof is cut to obtain metal fibers. For example, EMC;
5. <No. 55> pages 78 to 82. The coil material can be obtained by continuously winding a commercially available metal foil around a spindle drum. When rewinding,
It is desirable to perform surface treatment by applying or dipping a surface treatment agent on at least one surface of the metal foil. Instead of the surface treatment, it is also effective to wind the film while immersing it in a solution of a resin and coating the metal foil with the resin. In this case, it is more preferable to coat the same resin as the resin to be mixed later or a resin having good compatibility. Further, it is further preferable to use a material obtained by previously kneading the surface treating agent in the coating resin.

Further, it is also effective to produce a coil material by sandwiching a resin film between metal foils. At this time, it is more preferable to sandwich a resin that is the same as or compatible with the resin to be mixed later. It is further preferable to use a resin film in which the surface treatment agent is kneaded. In these winding treatments, the most preferable method is to apply or immerse a surface treating agent to the metal surface to improve the dispersibility of the metal fibers, to improve the electromagnetic wave shielding effect, and to improve the mechanical properties. it can.

Examples of the surface treatment agent used in the present invention include coupling agents such as titanate coupling agents, silane coupling agents, aluminate coupling agents, zirconia aluminate coupling agents, and triazine thiol compounds. Can be used. Of these, titanate-based coupling agents and silane-based coupling agents are particularly preferred.

When the coil material cutting method is used as the method for producing the metal fiber used in the present invention, the raw material metal foil is 35
μm or less, more preferably 30 μm
Or less, most preferably 20 μm or less. However, with a foil of 5 μm or less, there is a possibility that the foil may be cut when the foil is wound up, which is not so preferable. The addition amount of the metal fiber (A) is 1 to 70% by weight, preferably 5 to 4%.
0% by weight, more preferably 10 to 35% by weight.
If the amount of the fiber is too large, the surface appearance deteriorates, which is not preferable.
On the other hand, if the amount of fibers is too small, a sufficient shielding effect cannot be obtained.

The cross-sectional shape of the metal fiber (B) used in the present invention is not particularly limited, but the average diameter (circle-converted diameter) of a circle having the same cross-sectional area is the same as that of the metal fiber (A) in (B). 5 μm or more thicker than
The fibers are thicker than 0 μm. The optimum circle-converted diameter of the metal fiber (B) varies depending on the circle-converted diameter of the metal fiber (A), but specifically, the circle-converted diameter is preferably 30 to 100 μm, and more preferably 35 to 80 μm. If the fiber is too thin, it is difficult to improve the fiber processability, and if the fiber is too thick, the weight ratio of the metal fiber (B) increases, which is not preferable.

The metal fiber (B) can be obtained by a method such as a coil material cutting method, a bunching and drawing method, and a wire cutting method. The addition amount of the metal fiber (B) is 0.001 to 30% by weight, preferably 0.005 to 20% by weight, and more preferably 0.01 to 10% by weight. If the amount of the metal fiber (B) is too large, it is difficult to efficiently obtain a shielding effect, and if the amount is too small, it is difficult to improve fiber workability.

After the metal fibers (A) and (B) have been produced, or after they have been produced in advance into one fiber bundle,
Alternatively, the fibers are made into one fiber bundle at the same time as the fibers are produced, and then subjected to various processes. Metal fibers (A) and (B)
For example, as a method of obtaining a mixed fiber of (A) and (B), two kinds of metal foils having different thicknesses are stacked as a raw material foil, wound and cut by a coil material cutting method at a time.
After obtaining two types of fibers (A) and (B) having different circular equivalent diameters by using a raw material foil having one thickness each and using a coil material cutting method separately, These are combined to form a single fiber bundle, and further, a metal fiber (A) prepared by a coil material cutting method and a metal fiber (B) obtained by another method such as a bundle drawing method.
Various methods can be adopted, such as a method of forming a single fiber bundle.

The thermoplastic resin (C) used in the present invention includes low, medium and high density polyethylene, polypropylene, polyvinyl chloride, polystyrene, acrylonitrile-styrene copolymer (hereinafter abbreviated as SAN resin), acrylonitrile -Butadiene-styrene copolymer (hereinafter abbreviated as ABS resin), polyamide, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene ether, polymethyl methacrylate, polyetherimide, styrene-butadiene copolymer and the like Hydrogenated compositions and the like and polymer blends of combinations of two or more of these, for example, polycarbonate and acrylonitrile-butadiene-styrene copolymer, polyphenylene ether and polystyrene It can be mentioned. In particular, high impact polystyrene, SAN resin, ABS
Resins, polyphenylene ethers, polyamides and polycarbonates, these resins alone and alloys thereof are more preferred. A resin reinforced with glass fiber or carbon fiber, another filler, or the like can also be used.

The addition amount of these thermoplastic resins is the remaining amount of the metal fiber addition amount. In addition, the resin composition of the present invention may contain a flame retardant (for example, a phosphorus-based flame retardant, a halogen-based flame retardant, an inorganic flame retardant, etc.), an antioxidant, a lubricant, as long as the object of the present invention is not impaired. It may include a coupling agent, a triazine thiol compound, an inorganic filler, and the like.

In the present invention, the method of introducing the metal fiber into the resin is not particularly limited.
Method of kneading and extruding with resin after preparing master pellets cut to a certain fiber length, method of mixing while mixing fibers with resin small pieces in a mixer having high-speed rotating blades, mixing while cutting fibers, continuous from the middle of the extruder or from the beginning Method of extruding the resin while feeding the fiber, a method of applying a sizing agent to the metal fiber or forming a master pellet cut into a certain fiber length by coating the metal fiber with the resin in the manner of covering the electric wire as it is, And, a method of forming a metal fiber into a flat plate and then sandwiching it between resin sheets to form a sheet or compression molding, and forming the metal fiber into a flat plate and then performing sheet molding or compression molding together with the resin sheet to form a composite sheet and cutting it Thus, a method of forming a master pellet and then molding the same can be used.

The method of molding the electromagnetic wave shielding member from the resin composition of the present invention is not particularly limited, and is usually performed by an injection molding machine, a method by a melt press, vacuum molding, multilayer molding. And the like. Among them, a method of applying a sizing agent to a metal fiber or coating a metal fiber with a resin in the same manner as covering an electric wire as it is, forming a master pellet cut into a certain fiber length, and then molding is more preferable. The length of the pellet to be formed is preferably 0.5 to 50 mm, more preferably 1 to 20 mm, and further preferably 2 to 10 mm. In order to efficiently obtain a high electromagnetic wave shielding effect, it is preferable that the fiber has a large aspect ratio. However, a fiber that is too long is not preferable from the viewpoint of moldability and dispersibility. The cross-sectional shape of the master pellet is not particularly limited, but is crushed by a roller to a flat shape while the thermoplastic resin has plasticity from the viewpoint of dispersibility, and the resin is interposed between the conductive fibers at the stage of expanding the conductive fibers. Are more preferred.

After the metal fibers and the thermoplastic resin integrated by these methods are sized appropriately, they are mixed with the thermoplastic resin by a method such as dry blending, and injection molding, sheet molding, blow molding, etc. The shape is given by molding. Fibers are processed by these methods. At that time, by employing the method of the present invention, there is no trouble such as fiber breakage, and productivity can be significantly improved.

In the present invention, the master pellet is a mixture of the master pellet and the pellet containing no metal fiber, which is finally subjected to molding, as described above.
It contains more metal fibers than the final composition. The length of the master pellet is 0.5 to 50 mm, preferably 1 to
The thickness is 20 mm, more preferably 2 to 10 mm, and the thickness is 0.1 to 30 mm, preferably 0.1 to 10 mm. Examples of the shape include a cylindrical shape, a shape obtained by crushing a cylinder, a flat plate shape, a rectangular parallelepiped shape, a shape obtained by crushing a rectangular parallelepiped, a sphere, an oval sphere, and the like. The manufacturing method includes a method of attaching a resin around metal fibers such as an electric wire covering, a method of attaching a resin so as to sandwich a sheet-shaped metal fiber and cutting the resin into a predetermined size, and a method of applying a metal fiber around a fibrous resin. And cutting method.

The amount of the metal fiber (A) contained in the master pellet is 1 to 90% by weight, preferably 20 to 8% by weight.
It is 5% by weight, more preferably 40 to 85% by weight.
If the amount of the metal fiber (A) is too large, the fiber may be scattered. If the amount is too small, a large amount of master pellets must be added, so that the shielding effect cannot be obtained efficiently. The amount of the metal fiber (B) contained in the master pellet is 0.001 to 30% by weight, preferably 0.001 to 30% by weight.
The content is 5 to 20% by weight, more preferably 0.01 to 10% by weight. If the amount of the metal fiber (B) is too large, it is difficult to efficiently obtain a shielding effect, and if the amount is too small, it is difficult to improve fiber workability.

The resin composition for electromagnetic wave shielding in the present invention needs to have an electromagnetic wave shielding effect of 10 dB or more when molded, preferably 20 dB or more, more preferably 30 dB or more. It can be suitably used for electric products, automobile parts (gasoline automobiles, diesel engine automobiles, hybrid automobiles, electric automobiles, hydrogen automobiles, natural gas automobiles, etc.), train automobile parts, medical equipment and the like. Specific examples include personal computers, printers, scanners, switches, televisions, plasma displays, PHs
It can be suitably used as a housing for S, PDA, mobile phones, washing machines, refrigerators, dishwashers, copiers, microwave ovens, etc. and as internal and external parts. It can be suitably used as a conductive material and as an electromagnetic wave shielding material.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples. Each measurement is performed under the following conditions. Electromagnetic wave shielding effect (SE); 100 mm long x 100 mm wide x 1 mm thick in an anechoic box using a network analyzer MS4661A measuring device manufactured by Anritsu Corporation.
The test piece cut out at a frequency of 100 to 1000 MH
It is measured in the range of z and expressed as an 800 MHz attenuation value.

Surface appearance: 150 vertical by an injection molding machine
A flat sample having a size of 150 mm × width 150 mm × thickness 1 mm is formed, and the surface is visually evaluated. A good product is represented by ○, a slightly poor product is represented by △, and a poor product is represented by ×. Fiber workability (hardness to cut during fiber processing); The fiber bundle was covered with an electric wire covering device equipped with a single screw extruder.運 転 indicates that the fiber could be processed without running out of fiber once after operating for 1 hour, × indicates that there was 1 to 3 fiber breaks, and × indicates that there were 4 or more fiber breaks.

[0029]

Reference Example 1 (Adjustment of Metal Fiber Bundle) A metal fiber bundle is prepared as described below. In addition, the material of each metal and the circle-converted diameter of the metal fiber (A) are shown in the table. [Production of Metal Fiber Bundle a] A raw metal foil of 50 μm and a kind of raw metal foil selected from 10, 20, and 30 μm are piled up and wound by a coil material cutting method, and the metal fiber (A) has a circle-converted diameter of 15, 25, The fiber bundles of 1500 μm, 600 μm and 30 μm each and 25 fiber bundles of the metal fiber (B) having a circle-converted diameter of 50 μm and 25 fiber bundles are simultaneously produced, and bundled to form a metal fiber bundle a.

[Preparation of Metal Fiber Bundle b] 1500 metal fibers (A) having a diameter of 15 μm in a circle by a coil material cutting method and 50 μm in diameter of a metal fiber (B) having a diameter of a circle by a convergence drawing method.
Are produced and combined to form a metal fiber bundle b. [Preparation of Metal Fiber Bundle c] 1500 metal fibers (A) having a circle-converted diameter of 15 μm were prepared by a coil material cutting method. Used only with the metal fiber (A) without the metal fiber (B). (For Comparative Example) [Production of Metal Fiber Bundle d] 300 fibers of the metal fiber (B) having a diameter of 50 μm in terms of circle were produced by a coil material cutting method.
Used only with metal fiber (B) without metal fiber (A).
(For comparative example)

[0031]

Examples 1 to 10 According to the composition shown in Table 1, a metal type shown in Table 1 and a metal fiber (a or b) prepared by the preparation method shown in Reference Example 1 were extruded with a thermoplastic resin shown in Table 1. , Pulled out of the die, and cut into a length of 3 mm with a pelletizer to obtain a master pellet.
This master pellet was blended with the thermoplastic resin pellets shown in Table 1 so that the amount of fiber after blending became the amount shown in the table, and injection molding machine (JSW-J100SS-) was used.
II; manufactured by Japan Steel Works, Ltd.)
A molded product having a width of 150 mm and a thickness of 1 mm is formed. Table 1 shows the results of evaluating the electromagnetic wave shielding effect, surface appearance, and fiber workability of the molded product.

[0032]

Comparative Examples 1 to 3 Examples 1 to 6 were repeated except that the metal fiber c or the metal fiber d obtained in Reference Example 1 was used as the metal fiber.
The evaluation is performed in the same manner as described above. Table 1 shows the results.

[0033]

[Table 1]

In Table 1, PC / ABS is Japan G
E Plastic Co., Ltd .; Psychoroy MC5001
And AS are manufactured by Asahi Kasei Corporation; Stylac AS
T9106, PPE manufactured by Asahi Kasei Kogyo Co., Ltd .; Zylon 240Z, HIPS manufactured by Asahi Kasei Kogyo Co., Ltd .;

As can be seen from Table 1, the metal fibers (A) and (A) and (1) were prepared using the same metal type and different production methods from Examples 1, 2, 6, and 7 and Comparative Examples 1-2. B) are compared with Examples 1, 3, and 4, and Comparative Example 3 using metal fiber d and using only metal fiber (B). Comparative Examples 1 and 2 have significantly poor fiber workability. Comparative Example 3 has good fiber workability, but is inferior in both electromagnetic wave shielding properties and surface appearance.

[0036]

Industrial Applicability The resin composition of the present invention is a resin composition having good fiber processability, excellent electromagnetic wave shielding effect and surface appearance, and is particularly excellent as a composition for electromagnetic wave shielding.

Claims (3)

[Claims] (A) A metal fiber 1 having a diameter of less than 50 μm in terms of a circle
To 70% by weight, (B) a thermoplastic resin composition comprising 0.001 to 30% by weight of a metal fiber having a diameter of 5 μm or more thicker than (A), and (C) 98.999 to 29% by weight of a thermoplastic resin. . 2. A metal fiber 1 having a diameter less than 50 μm in terms of a circle.
(B) 0.001 to 30% by weight of a metal fiber having a circular equivalent diameter of 5 μm or more than (A) and (C) 98.999 to 29% by weight of a thermoplastic resin. Stuff. 3. A metal fiber 1 having a diameter of less than 50 μm in terms of circle (A).
(B) 0.001 to 30% by weight of a metal fiber having a diameter of 5 μm or more larger than (A) and (C) 98.999 to 9.999% by weight of a thermoplastic resin. Master pellet.