JPH0987528A - Resin composition containing metal fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition having excellent electromagnetic-wave- shielding properties and good dispersibility, rigidity and surface appearance by mixing a thermoplastic resin (A) with a metal fiber (B) prepared by a coil material cutting method. SOLUTION: Component A is not particularly limited and is exemplified by a low-, medium- or high-density polyethylene, a polypropylene, a polyvinyl chloride or a blend of at least two of these polymers. The metal of the metal fiber is desirably stainless steel, brass, copper, aluminum, iron, gold, silver, nickel or titanium. The coil material cutting method is a method for obtaining a metal fiber by mounting a coiled metal foil on a metal fiber production apparatus resembling a lathe in structure and function and cutting its end. Before a metallic sheet is coiled, it is desirably surface-treated by coating at least either surface of the sheet with a surface treating agent (e.g. titanate coupling agent) or immersing the sheet in the agent. The metal fiber has a substantially rectangular cross-section, a fiber diameter of 1-500μm and a fiber length of 0.1mm or above.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a conductive material having improved electromagnetic wave shielding properties, dispersibility, rigidity and surface appearance, and more particularly to an electromagnetic wave shielding member.

[0002]

2. Description of the Related Art Electric circuits and ICs are used in various electric devices, but they sometimes malfunction due to electromagnetic waves generated from outside or 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 electromagnetic wave shielding properties. For these materials, a method of forming a conductive film on a resin molded product by plating, painting, thermal spraying or the like is adopted, but a separate step is required and cost is required. Therefore, the resin itself is given a shield property. 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 these, the method using metal fibers shows higher shielding properties in a small amount.
Conventionally, a focused wire drawing method, a melt spinning method, and the like are known for producing fine metal fibers. Either way,
There are drawbacks such as many steps and cost to obtain thin metal fibers, and it is not possible to obtain long fibers, and even if kneaded with resin, electromagnetic wave shielding property, rigidity, surface appearance, etc. should be at a satisfactory level. Had not arrived.

Further, when these metal fibers are filled in a resin, there are problems that dispersion failure occurs, a sufficient electromagnetic wave shielding effect cannot be obtained, and the mechanical strength of a molded product is lowered. A method for providing a layer of a coupling agent on the surface of metal fibers in order to improve the dispersibility of the metal fibers is disclosed in, for example, JP-A-60-18314 and JP-A-60-11.
Although disclosed in Japanese Patent No. 2854, these do not use the fiber of the coil material cutting method, and the surface treatment is performed after the fiber is produced.

[0004]

Under the circumstances, the present invention has excellent dispersibility of metal fibers, electromagnetic shielding property, and
Provided are a metal fiber-filled resin composition excellent in impact strength, rigidity, surface appearance, and the like, an electromagnetic shield member using the same, and a metal fiber suitable for producing the metal fiber-filled resin composition and a method for producing the same. It is intended for that.

[0005]

Under these circumstances, the present invention has been accomplished as a result of intensive studies on electromagnetic wave shielding materials.

That is, the present invention provides (I) a thermoplastic resin 99.
To 30 wt% and (II) 1 to 70 wt% of metal fibers produced by the coil material cutting method, and an electromagnetic wave shield member. Furthermore, it is characterized in that the metal fiber of (II) is treated with a surface treatment agent.

The present invention will be described in detail below.

The thermoplastic resin used in the present invention is not particularly limited, but examples thereof include low, medium and high density polyethylene, polypropylene, polyvinyl chloride, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer. Combined (hereinafter ABS
Abbreviated as resin), polyamide, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene ether (hereinafter P
Abbreviated as PE), polymethylmethacrylate, polyetherimide, styrene-butadiene copolymers and hydrogenated compositions thereof, and polymer blends of two or more thereof, such as polycarbonate and acrylonitrile-butadiene-styrene copolymer. Coalescence, polyphenylene ether, polystyrene, etc. can be mentioned. In particular, high impact polystyrene (hereinafter referred to as HIPS
Abbreviated), acrylonitrile-styrene copolymer,
Acrylonitrile-butadiene-styrene copolymer, polyphenylene ether, polyamide and polycarbonate, homopolymers of these resins, and alloys thereof are preferred. Resins reinforced with glass fibers or carbon fibers can also be used.

The metal species of the metal fibers used in the present invention are stainless steel, brass, copper, aluminum, iron, gold,
Silver, nickel, titanium, tin, lead, antimony, zinc, cadmium, magnesium, tungsten, platinum, lithium, molybdenum, beryllium and alloys of two or more of these, or alloys containing these as the main constituents, and phosphorus with these. And the like. Among these, stainless steel, brass, copper, aluminum, iron,
Gold, silver, nickel and titanium are preferred.

The coil material cutting method is a method for obtaining a metal fiber by mounting a metal foil plate in a coil material shape on a metal fiber manufacturing apparatus having a structure and a function substantially similar to a lathe and cutting the end face thereof. is there. For example, EMC 1992.11.5. <
No. 55> pages 78 to 82. The coil material is obtained by continuously winding a commercially available metal foil on a spindle drum.

At the time of winding, it is desirable that at least one surface of the metal plate is surface-treated by applying or dipping it on a surface-treating agent. Further, instead of such a surface treatment, it is also effective to dip it in a solution in which the resin is dissolved and coat the metal foil with the resin to wind it up. 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 more preferable to use a material obtained by previously kneading the surface treatment agent in the coating resin.

Further, it is also effective to produce a coil material by sandwiching a resin film between metal foils. At that time, it is more preferable to sandwich a resin having the same or good compatibility with the resin to be mixed later. Further, it is more preferable to use a resin film in which the surface treatment agent is kneaded.

In these winding treatments, the method of applying the surface treatment by coating or dipping the surface of the metal on the metal surface is most preferable, and the dispersibility of the metal fibers is improved, and the electromagnetic wave shielding property and the mechanical property are improved. Can be made.

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

Examples of titanate coupling agents include isopropyl triisostearoyl titanate, isopropyl octanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl isostearoyl diacrylic titanate, isopropyl tri (dioctyl phosphate). ) Titanate, isopropyl lycumyl phenyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (n-aminoethyl-aminoethyl) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraoctyl bis (ditridecyl phosphite) Titanate, tetra (2,2-diallyloxymethyl-1) Heptyl) bis (ditridecyl) phosphite titanate, dicumyl phenyloxy acetate titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, diisostearoyl ethylene titanate, piston (dioctyl pyrophosphate) ethylene titanate. Among them, isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (n-aminoethyl-aminoethyl) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraoctyl bis Preferred are (ditridecyl phosphite) titanate, tetra (2,2-diallyloxymethyl-1-putyl) bis (ditridecyl) phosphite titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, pis (dioctyl pyrophosphate) ethylene titanate. .

Examples of the silane-based coupling agent include vinyl-based ones such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, vinyltris (βmethoxyethoxy) silane, and amino-based N- ( 2-Aminoethyl) 3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl)
3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltriethoxysilane,
3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, epoxy-based compounds such as 3-glycidoxypropyltrimethoxysilane,
-Glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,
4-epoxycyclohexyl) ethyltrimethoxysilane, chloro-based ones such as 3-chloropropylmethyldimethoxysilane and 3-chloropropyltrimethoxysilane, and methacryloxy-based ones such as 3-methacryloxypropyltrimethoxysilane and 3-methacryl Roxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-mercaptopropyltrimethoxysilane as a mercapto type, N- (2- (Vinylbenzylamino) ethyl) -3-aminopropyltrimethoxysilane / hydrochloride and the like.

Examples of the aluminate-based coupling agent include acetoalkoxyaluminum diisopropylate.

Examples of the zirconia aluminate-based coupling agent include alcohol-based and glycol-based coupling agents.

[0019]

Embedded image

Examples of triazine thiol compounds include:
Triazine trithiol monosodium (TTN) etc. are mentioned.

These surface treatment agents may be used alone or in combination of two or more. Further, these surface treatment agents may be used without being directly diluted, or may be diluted with water, an organic solvent, a thermoplastic resin, or the like. Further, as a method of applying these to the metal surface, a method of previously applying to a metal plate and then cutting may be used, or fibers may be sprayed by dipping or spraying on the surface treatment agent after cutting or continuously with the step of cutting. A method may be used.

The cross-sectional shape of the fiber obtained by the coil material cutting method becomes substantially rectangular, and the cross-sectional shape of the fiber produced by the conventional focused wire drawing method is fan-shaped or polygonal. To be distinguished. When the metal plate surface of the coil material is treated with the surface treatment agent, the surface treatment agent remains on at least one surface having the same width as the plate thickness of the coil material, but is newly generated after cutting. The surface treatment agent is not present on the remaining surface.

The fiber diameter is 1 μ to 500 μ, preferably 3 to
It is 100μ, and more preferably 10 to 60μ. The fiber length is 0.1 mm or more in the dispersed resin, preferably 0.
5 mm or more. The fibers obtained by the coil material cutting method of the present invention are produced as continuous long fibers. The method of introducing this fiber into the resin is not particularly limited,
For example, a method of adding a sizing agent and cutting it into a constant fiber length, then blending it with a resin and kneading and extruding it, a method of mixing the resin pieces with a mixer having a high-speed rotating blade while cutting the fiber into short pieces, in the middle of an extruder or A method of extruding a resin while continuously feeding fibers from the original, a method of attaching a sizing agent to a metal fiber or coating the resin as it is, cutting it to a constant fiber length, and then blending with a resin containing no fiber, and molding. Examples include a method of forming the metal fiber of the present invention into a flat plate shape, and then sandwiching the sheet between sheets to perform sheet molding or compression molding. In the present invention, the metal fiber is 1 to 70% by weight, preferably 3
.About.50% by weight, more preferably 5 to 35% by weight.

The resin composition of the present invention contains various stabilizers, plasticizers, flame retardants, pigments, as long as the characteristics thereof are not impaired.
An inorganic filler or the like can be appropriately added and used according to a known method. In particular, when used as an electromagnetic wave shielding member, it is more preferable to use a flame retardant in combination.

The electromagnetic wave shield material in the present invention is
It is necessary that the electromagnetic wave shielding effect is 10 dB or more,
It is preferably 20 dB or more, and more preferably 30 dB or more. Specific examples of the use of the material include housings of televisions, mobile phones, personal computers, NES, game machines, air conditioners, copying machines, microwave ovens, internal parts, members that cover circuits, medical equipment, and electronic equipment of automobiles. Used as a covering material.

No particular limitation is imposed on the method for molding the electromagnetic wave shielding member from the resin composition of the present invention, and molding by an injection molding machine which is usually performed, a method by a melt press, a vacuum molding, or a multilayer molding is performed. Sheet molding including is used.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

Each measurement is performed under the following conditions.

Electromagnetic wave shield effect: A spectrum analyzer MS623A measuring instrument manufactured by Anritsu Corporation and a tracking generator MH628A were used to measure a test piece having a thickness of 100 × 100 × 2 mm in a frequency range of 100 to 1000 MHz in an anechoic box. 500 MH
It is represented by the attenuation value of z.

Izod impact strength; ASTM D25
Measure in accordance with 6.

Flexural modulus; measured according to ASTM D790.

Dispersibility: The dispersion state of the metal fibers in the injection-molded product was observed with a soft X-ray inspection device (SV-100A manufactured by Softex Co.), and a good product was ◯, a better product was ◎, and a poor product. Is represented by x.

Surface appearance: The surface condition of the injection-molded article is visually observed, and a good product is represented by ◯, a better product is represented by ⊚, and a defective product is represented by x.

Reference Example 1 Production of Metal Fiber by Coil Cutting Method EMC 1992.11.5. <No. 55> p7
Stainless steel based on the method described in 8 to 82,
Brass and aluminum metal fibers were produced.

That is, using the apparatus shown in FIG.
On both sides of 0 μm thin metal plate,
% Aqueous solution is continuously applied by a coating roll,
After drying with a coating drying heater to a coating thickness of about 20 μm (this coating operation was omitted for brass), the turning spindle drum of a metal fiber manufacturing device with the same structure and function as the lathe shown in FIG. 2 was used. A metal thin plate is wound 300 times, and its end face is cut with a cutting blade at a tool feed rate of 10 μm / rev to obtain a metal fiber.
The obtained fiber cross section has one side corresponding to the plate thickness of the coil material,
The other side shows a rectangular shape determined by the feed amount of the tool.
The cross-sectional area of the fiber was measured by a cross-sectional photograph of the fiber, and the converted diameter converted into the diameter of the circular cross section was 30 μm on average.

Reference Example 2 The procedure of Reference Example 1 was repeated except that polystyrene latex was used instead of polyvinyl alcohol.

Reference Example 3 Stainless metal fibers were produced by the chatter vibration method.
The length is 2 mm and the average diameter is 30 μ.

Reference Example 4 In Reference Example 1, instead of polyvinyl alcohol, a titanate coupling agent (Planeact K manufactured by Ajinomoto Co., Inc.) was used.
R38S) is used in the same manner except that a 3% hexane solution is used.

Reference Example 5 Instead of polyvinyl alcohol in Reference Example 1, a silane coupling agent (KBM50 manufactured by Shin-Etsu Silicone Co., Ltd.) was used.
The same operation is performed except that the 3% aqueous solution of 3) is used.

Reference Example 6 In Reference Example 1, 3% was used instead of polyvinyl alcohol.
The same procedure is performed except that the polystyrene latex containing the titanate coupling agent (Planeact KR38S manufactured by Ajinomoto Co., Inc.) is used.

Reference Example 7 Using the different material laminating and winding device shown in FIG. 3, a metal thin plate and a 3% titanate cup were used for a turning spindle drum of a metal fiber manufacturing device having the same structure and function as the lathe shown in FIG. HIPS containing a ring agent (Planeact KR38S manufactured by Ajinomoto Co., Inc., polystyrene 4 manufactured by Asahi Kasei Corporation)
33) A film (20 μm thick) is wound 300 times to make a laminated coil material, and the end face is a tool feed rate of 10 μm / rev
A mixed fiber of plastic and metal is obtained by cutting with a cutting blade at a speed of. The cross-sectional area of the metal fiber portion was measured from a cross-sectional photograph of the fiber, and the converted diameter converted into the diameter of the circular cross section was 30 μm on average.

Examples 1 to 3 Metal fibers are produced by the method of Reference Example 1. Then H
IPS (Asahi Kasei Kogyo Co., Ltd. polystyrene 433) is fed from a normal feed port, and metal fibers of the types shown in the table are continuously fed from the vent port of an extruder (Ikegai Tekko Co., Ltd. PCM 30 mm twin screw extruder). Is extruded while kneading with the resin to obtain pellets. The amount of metal contained in the pellets was measured, and HIPS was added at the time of injection molding so that the amount ratio shown in the table was obtained, and an injection molding machine (FUNAC AUTOSHOT Tseries) was used.
s MODEL 50D) to prepare a test piece.

Example 4 The same procedure as in Example 1 was carried out except that a blended product of polycarbonate and ABS resin (hereinafter abbreviated as PC / ABS resin) (Cycoloy C2800 manufactured by Ube Saikon Corporation) was used instead of HIPS. did.

Example 5 The same procedure as in Example 1 was carried out except that an ABS resin (VA51 (flame retardant grade) manufactured by Asahi Kasei Corporation) was used instead of HIPS.

Example 6 Instead of HIPS, polyphenylene ether (PP
E: number average molecular weight 14,000 determined by GPC, weight average molecular weight 24,500) 30% by weight, HIPS (H8117 manufactured by Asahi Chemical Industry Co., Ltd.) 67% by weight, styrene-
The same procedure as in Example 1 was performed except that 3% by weight of a hydrogenated butadiene block copolymer (Tuftec H1061 manufactured by Asahi Kasei Kogyo Co., Ltd.) was used.

Example 7 The procedure of Example 1 was repeated, except that the same amount of the metal fiber of Reference Example 2 was used instead of using the metal fiber of Reference Example 1.

Example 8 HIPS was applied to the surface of metal fibers cut by the method of Reference Example 4.
(Polystyrene H8117 manufactured by Asahi Kasei Co., Ltd.) was extrusion-coated, and the extruded product containing metal fibers was cut into a length of 5 mm and pelletized to obtain a master pellet. The amount of metal fiber after blending this master pellet is 20
It is dry-blended with natural pellets of HIPS (polystyrene H8117 manufactured by Asahi Kasei Co., Ltd.) so as to be wt%, and injection-molded.

Example 9 The procedure of Example 8 was repeated, except that the metal fibers cut by the method of Reference Example 4 were replaced by the metal fibers cut by the method of Reference Example 5.

Example 10 The procedure of Example 8 was repeated, except that the metal fibers cut by the method of Reference Example 4 were replaced by the metal fibers cut by the method of Reference Example 6.

Example 11 The mixed fiber cut by the method of Reference Example 7 was heated by the apparatus shown in FIG. 4 to melt the plastic, thereby concentrating the metal fiber and cutting it to a length of 5 mm and mixing the metal fiber. Get plastic pellets. HIPS so that the amount of metal fibers after blending these pellets becomes 20 wt%
Dry blend with a pellet (polystyrene H8117 manufactured by Asahi Kasei Co., Ltd.) (without metal fiber) and injection molding.

Example 12 3% of the silane coupling agent (KBM503 manufactured by Shin-Etsu Silicone Co., Ltd.) was used for the metal fiber cut by the method of Reference Example 1.
After dipping in an aqueous solution and drying, HIPS (polystyrene H8117 manufactured by Asahi Chemical Industry Co., Ltd.) was extrusion-coated on the surface of the metal fiber, and the extruded product containing the metal fiber was cut into a length of 5 mm and pelletized to obtain a master pellet. The amount of metal fiber after blending this master pellet is 20 wt%
So as to obtain a dry blend with natural pellets of HIPS (polystyrene H8117 manufactured by Asahi Kasei Corporation), and injection molding is performed.

Example 13 When cutting a coil material, cutting was carried out by the method of Reference Example 1 except that the silane coupling agent (KBM503 manufactured by Shin-Etsu Silicone Co., Ltd.) was sprayed while spraying a 3% aqueous solution. The surface was extrusion-coated with HIPS (polystyrene H8117 manufactured by Asahi Kasei Corporation), and the extruded product containing metal fibers was cut into a length of 5 mm and pelletized to obtain a master pellet. HIPS (polystyrene H8 manufactured by Asahi Kasei Kogyo Co., Ltd.) was used so that the amount of the metal fibers after blending the master pellet was 20 wt%.
Dry blend with the natural pellet of 117) and perform molding.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the same amount of the metal fiber of Reference Example 3 was used in place of the metal fiber of Reference Example 1 in Example 1.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the same amount of the metal fiber of Reference Example 3 was used in place of the metal fiber of Reference Example 1 in Example 4.

Comparative Example 3 The procedure of Example 1 was repeated except that the same amount of the metal fiber of Reference Example 3 was used in place of the metal fiber of Reference Example 1 in Example 5.

Comparative Example 4 The procedure of Example 1 was repeated except that the same amount of the metal fiber of Reference Example 3 was used in place of the metal fiber of Reference Example 1 used in Example 6.

[0057]

[Table 1]

As can be seen from Table 1, Example 1 is superior in flexural modulus and surface appearance as compared with Comparative Example 1, and the electromagnetic wave shielding property is obtained even though the same amount of metal fiber is added. Is also excellent. Further, in Examples 8 to 11, the dispersed state of the fibers is good and the electromagnetic wave shielding effect is high.

[0059]

As described above, the metal fiber of the present invention has excellent dispersibility in resin, and the resin composition of the present invention filled with the metal fiber has excellent electromagnetic wave shielding properties, dispersibility, rigidity and surface appearance. Is good.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a coil material coating device.

FIG. 2 is a schematic explanatory view of an apparatus for producing metal fibers by a coil cutting method.

FIG. 3 is a schematic explanatory view of a dissimilar material laminated winding device.

FIG. 4 is a schematic explanatory view of an apparatus for producing metal fiber-mixed plastic pellets.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location H01B 1/22 H05K 9/00 X H05K 9/00 7310-4F B29C 67/14 X // H01F 1 / 00 H01F 1/00 C B29L 31:34

Claims (10)

[Claims] 1. A resin composition comprising (I) 99 to 30% by weight of a thermoplastic resin and (II) 1 to 70% by weight of metal fibers produced by a coil material cutting method. 2. The resin composition according to claim 1, wherein the metal fiber produced by the coil material cutting method is treated with a surface treatment agent. 3. A method of manufacturing a fiber produced by a coil material cutting method, wherein a metal plate having a surface treatment agent intervened when it is wound around a spindle drum is used as a coil material, and an end face thereof is cut. A method for producing a metal fiber. 4. The method for producing a metal fiber according to claim 3, wherein the surface treatment agent is applied to the surface of the metal plate. 5. The method for producing metal fibers according to claim 3, wherein a resin solution containing a surface treatment agent is applied to the surface of the metal plate. 6. The method for producing a metal fiber according to claim 3, wherein a resin film in which a surface treatment agent is kneaded is interposed between metal plates and is wound up in layers. 7. A metal fiber produced by a coil material cutting method and having at least one surface treated with a surface treatment agent. 8. A metal fiber produced by a coil material cutting method, at least one surface of which is not treated with a surface treatment agent. 9. The resin composition according to claim 1, comprising the metal fiber produced by the method according to claim 3, 4, 5 or 6, or the metal fiber according to claim 7 or 8. 10. An electromagnetic wave shielding member molded from the resin composition according to claim 1.