JP4670428B2 - Electromagnetic wave shield molding - Google Patents

Description

  The present invention relates to an electromagnetic wave shield molded article. More specifically, the present invention relates to an electromagnetic wave shield molded article excellent in moldability and snap fit property in addition to the electromagnetic wave shielding property.

  In order to reduce the influence of noise caused by electromagnetic waves generated from electronic devices, there is known an electromagnetic wave shielding technique that shields electromagnetic waves by imparting conductivity to the housing or the like.

  As a casing having electromagnetic wave shielding properties, for example, a casing provided with conductivity by applying metal plating to the surface of a molded product made of a thermoplastic resin such as polycarbonate resin or ABS resin is known.

  However, the method of performing metal plating on the surface of the molded product requires a plating process, which complicates the manufacturing process, and in the case of a molded product having a complicated shape, there is a problem that the plating process is difficult. .

  In order to eliminate the complexity of the manufacturing process as described above, a molded article made of a resin composition containing a conductive material such as metal flakes, metal fibers, carbon fibers, or metal-coated carbon fibers instead of metal plating treatment. There has been proposed a method for obtaining a casing having electromagnetic wave shielding properties by using it.

  For example, Patent Document 1 discloses a thermoplastic resin molded article containing metal-coated carbon fibers, wherein the content of metal-coated carbon fibers is 13 to 35% by weight, and the fiber length in all metal-coated carbon fibers is 270. An electromagnetic wave shielding resin molded product is disclosed in which fibers in the range of ˜800 μm occupy 8% by weight or more of the molded product.

  Patent Document 2 discloses that the thermoplastic resin (rubber reinforced styrene resin or a mixture of a rubber reinforced styrene resin and another thermoplastic resin) (A) is 100 parts by weight of metal-coated fibers (B) 5 to 30. An electromagnetic wave shielding resin composition comprising 3 parts by weight of zinc oxide whisker (C) 3 to 20 parts by weight and titanium oxide (D) 0.5 to 10 parts by weight is disclosed.

  However, since the fibrous filler-containing composition for obtaining a resin molded article for electromagnetic wave shielding as described in Patent Document 1 or Patent Document 2 is kneaded with a single-screw or twin-screw extruder, a kneader, or the like. When the fiber is broken and the fiber length is shortened, the reinforcing effect of the fibrous filler is reduced, and particularly when a molded product having a thin part that requires mechanical strength is molded with the above composition, cracking or Cracks sometimes occurred.

One example is an electromagnetic shielding molded product used for components such as a memory card used in a notebook computer, a mobile phone, a video camera, a digital camera, and the like. This type of housing may have a recess or the like for housing a semiconductor device or the like inside, but in this case, the portion may be an extremely thin portion having a thickness of 0.5 mm or less. In addition, when adopting a snap fit structure in which a housing or various devices are fixed using a resin nail, the resin nail portion is also an extremely thin portion. When an electromagnetic wave shield molded product as described in Patent Document 1 or Patent Document 2 is used for the electromagnetic wave shield molded product having such a thin portion, sufficient mechanical properties cannot be sufficiently maintained. Cracks and cracks sometimes occurred.
Japanese Patent No. 2735748 JP 2000-129148 A

  The present invention has been made in order to solve the above problems, and in an electromagnetic wave shield molded product having a thin portion of 0.5 mm or less, it has excellent electromagnetic wave shielding properties and has a snap fit structure with a very thin portion as a resin nail. It is an object of the present invention to provide an electromagnetic wave shield molded product that can suppress the generation of cracks and cracks even when using.

  As a result of intensive studies to solve the above problems, the present inventors have found that the problem can be solved by the following means.

That is, the invention of claim 1 contains 55 to 75 % by mass of at least one resin selected from ABS resin, MBS resin and modified resins thereof containing 15 to 35% by mass of a polybutadiene component, and polycarbonate resin. Is a resin pellet having a longitudinal length of 5 to 10 mm containing a thermoplastic resin containing 25 to 45 mass% and conductive fibers, and the length in the longitudinal direction is the fiber length of the conductive fibers The present invention relates to an electromagnetic wave shield molded article having a portion of 0.5 mm or less obtained by injection compression molding using resin pellets characterized by being substantially equal.

  Further, the resin pellet is preferably composed of 70 to 85% by mass of a thermoplastic resin and 15 to 30% by mass of conductive fibers from the viewpoint of particularly excellent balance between electromagnetic wave shielding properties and snap fit properties (Claim 2).

  Furthermore, when the ABS resin, MBS resin and their modified resins have a mass reduction rate of 3% by mass or less at a temperature increase of 10 ° C./min and a temperature of 300 ° C., the generation of mold deposits can be suppressed. (Claim 3).

The electromagnetic wave shield molded product of the present invention is preferable from the viewpoint of providing good electromagnetic wave shielding properties and mechanical properties when used in a molded product having a complicated shape such as a casing for a portable device or its internal mechanism parts. 4 ).

  The electromagnetic wave shield molded product of the present invention is a molded product that requires electromagnetic shielding properties, in particular, an electromagnetic wave shield molded product having a thin portion, wherein the electromagnetic wave shield molded product is excellent in electromagnetic wave shielding properties and has a thickness of 0.5 mm or less. Even a portion having an extremely thin portion can be molded well, and even when a snap-fit structure having a thin portion as a resin nail is used, the occurrence of cracks and cracks can be suppressed.

The electromagnetic wave shield molded article of the present invention contains 55 to 75 % by mass of at least one resin selected from ABS resin, MBS resin and modified resins thereof containing 15 to 35% by mass of a polybutadiene component, and is a polycarbonate resin. Is a resin pellet having a longitudinal length of 5 to 10 mm containing a thermoplastic resin containing 25 to 45 mass% and conductive fibers, and the length in the longitudinal direction is the fiber length of the conductive fibers It is obtained by injection compression molding using resin pellets characterized by being approximately equal.

  ABS resins, MBS resins and their modified resins (hereinafter also referred to as "ABS resins") include ABS resins, methyl methacrylate, butadiene, which are thermoplastic resins mainly composed of acrylonitrile, butadiene and styrene. In addition to MBS resins mainly composed of styrene, modified resins such as maleic acid-modified resins can be used. Of these, ABS resins and their modified resins are preferred.

  The ABS resin or the like in the present invention contains 15% by mass or more of a polybutadiene component. For this reason, the electromagnetic wave shield molded product excellent in snap fit property can be obtained.

  The ratio of a polybutadiene component is 15-35 mass%, Preferably it is 20-30 mass%. When the ratio is less than 15% by mass, the elasticity is low, and cracks or the like occur when a semiconductor device or the like is engaged with the housing using a resin nail for thin snap fitting (hereinafter also referred to as a resin nail). May occur. On the other hand, when it is 35% by mass or more, the rigidity of the molded product is low, so that the snap-fit holding force is low, and the heat resistance tends to be lowered.

  When the polybutadiene component is contained in an amount of 15% by mass or more, it takes a long time to solidify at the time of injection molding, and a high compressibility can be obtained. The content ratio of the polybutadiene component is calculated by, for example, measuring the weight by separating only the polybutadiene component with a solvent that does not dissolve only the polybutadiene component in the ABS resin or the like.

  The polybutadiene component includes not only a butadiene homopolymer but also a copolymer of a component copolymerizable with butadiene.

  The production method of the ABS resin or the like is not particularly limited, and examples thereof include a graft method, a blend method, and a graft-blend method. Among them, in particular, an ABS resin obtained by the graft-blend method is a resin having a small domain size of the polybutadiene component and a homogeneous characteristic, and thus is preferable from the viewpoint of excellent adhesion to carbon fibers. The graft-blend method is an emulsion polymerization method in which a base polymer such as an ABS resin having a large polybutadiene component is produced, and this base polymer is further diluted with an AS resin obtained by an emulsion polymerization method, a bulk polymerization method, or a bulk suspension polymerization method. It is a manufacturing method.

  The ABS resin or the like in the present invention preferably has a mass reduction rate of 3% by mass or less at a temperature increase of 10 ° C./min and a temperature of 300 ° C. If the mass reduction rate exceeds 3% by mass, mold deposits tend to occur on the surface of the molded product. Therefore, it is preferable that the mass reduction rate is smaller.

  Further, as the ABS resin or the like, those having a thin wall portion at a load deflection temperature (ASTM D648, load 1.82 MPa) of 85 ° C. or more are preferable. Furthermore, when ABS resin and MBS resin are used in combination, it is preferable from the viewpoint that moldability and demoldability can be improved.

  Examples of the ABS resin containing 15% by mass or more of the polybutadiene component in the present invention include “Clarastic” and “Santac” manufactured by Nippon A & L Co., Ltd., “Psycolac” manufactured by UMGABS Co., Ltd., and Toray Industries, Inc. In addition to ABS resin such as “Toyolac” manufactured by), maleimide-based modified ABS resin such as “Bulksum” manufactured by UMGABS Co., Ltd., and MBS resin such as Metabrene (trade name) manufactured by Mitsubishi Rayon Co., Ltd. These may be used alone or in combination of two or more.

The thermoplastic resin in the present invention contains 55 to 75 % by mass of an ABS resin or the like. When the ratio is less than 55 % by mass, it is difficult to obtain sufficient snap fit and moldability even with an ABS resin containing a large amount of a polybutadiene component.

  Examples of the resin component other than the ABS resin and the like contained in the thermoplastic resin in the present invention include a polycarbonate resin. When a polycarbonate resin is used, the mechanical properties of the molded product can be improved and the snap fit can be further improved.

  The polycarbonate-based resin is obtained from dihydroxydiarylalkane, and may be arbitrarily branched. This polycarbonate resin is produced by a known method, but is generally produced by reacting a hydroxy and / or polyhydroxy compound with phosgene or a diester of carbonic acid.

  When a polycarbonate resin with an Izod impact strength at −30 ° C. of 100 J / m or more is used, the resulting electromagnetic shielding molded product has a high impact property even in a low temperature environment and is near the snap-fit resin nail. Suppresses the generation of cracks.

  Polycarbonate resins having a MFR (melt flow rate; JIS K7210) value of 280 ° C. and a load of 2.1 kg of 10 g / min or more are resin compositions for obtaining the molded product of the present invention. Since the fluidity does not decrease, a thin molded product can be easily formed.

  Examples of the polycarbonate-based resin include “Caliver” manufactured by Sumitomo Dow, “Iupilon” manufactured by Mitsubishi Engineering Plastics, “Panlite” manufactured by Teijin Chemicals, Ltd., and the like. These may be used alone or in combination of two or more.

The blending ratio in the case of using a polycarbonate-based resin is preferably 25 to 45 % by mass in the thermoplastic resin from the viewpoint of improving the mechanical properties without reducing the molding fluidity.

  The resin pellet in the present invention contains conductive fibers in addition to the thermoplastic resin.

  Examples of the conductive fiber include carbon fiber, metal-coated carbon fiber, metal fiber such as stainless steel fiber, aluminum fiber, copper fiber, brass fiber, and metal-coated glass fiber. Among these, carbon fiber or stainless fiber is preferable from the viewpoint of excellent electromagnetic shielding properties.

  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 steel fibers include: For example, Nippon Seisen Co., Ltd., Bekaert stainless steel fiber, etc. are mentioned.

  The conductive fiber is preferably surface-treated with a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, or the like in order to enhance the adhesion with the resin component.

  As the fiber diameter of the conductive fibers, those having an average diameter of about 7 to 17 μm provide excellent electromagnetic shielding properties to the molded product of the present invention, and also provide a high reinforcing effect to a thin portion used for snap-fit. preferable.

  The resin pellet in the present invention is a pellet containing a thermoplastic resin and conductive fibers, the length in the longitudinal direction is 5 to 10 mm, and the length in the longitudinal direction is substantially equal to the fiber length of the conductive fibers. It is a feature.

  Although the manufacturing process of the said resin pellet is not specifically limited, The typical example is demonstrated based on FIG.

  In FIG. 1, 1 is a bundled filament, 2 is a molten resin supply device, 3 is a resin impregnation device, 4 is a shaping device, 5 is a cooling device, 6 is a pelletizing device, 7 is a resin pellet, and 8 is a fiber / resin. The complex is shown.

  First, the converged filament 1 is introduced into the resin impregnation apparatus 3.

  The bundled filaments are bundles of, for example, about 500 to 30,000 conductive fiber filaments. More specifically, carbon fibers are about 500, 1000, 3000, 6000, 12000, 24000. However, 5000 and 12000 stainless steel fibers are commercially available.

  There are no particular restrictions on the method of focusing, such as the focused filaments being focused using a sizing agent or the like, or physically focused by twisted yarn or the like.

  The converged filament 1 is supplied to the resin impregnation apparatus 3, and the resin impregnation apparatus 3 is preliminarily equipped with a molten resin supply apparatus 2.

  The molten resin supply device 2 is a device capable of melting a resin, such as a single-screw or twin-screw extruder, and supplies the molten resin to the resin impregnation device 3. The bundled filaments 1 supplied to the resin impregnation apparatus 3 are impregnated with molten resin, and a fiber / resin composite 8 is formed.

  At this time, it is preferable to adjust the supply rate of the molten resin and the supply rate of the conductive fibers so that the obtained resin pellets contain 15 to 30% by mass of the conductive fibers.

  When the proportion is less than 15% by mass, sufficient electromagnetic wave shielding properties and snap fit properties cannot be obtained, and when it exceeds 30% by mass, the fluidity may be lowered, and thin-wall molding tends to be difficult. There is.

  Next, the fiber / resin composite 8 is sent to the shaping device 4 in a semi-solid state, and after the strand shape is adjusted, it is sent to the cooling device 5.

  The cooling device 5 may be a known cooling device used when forming pellets from a molten resin. For example, cooling according to strand characteristics such as a method of immersing in a water tank, a method of spraying water, or an air cooling method. You can choose the device.

  The fiber / resin composite 8 cooled by the cooling device 5 is pelletized by the pelletizing device 6.

  In addition, although the resin pellet used in this invention is pelletized so that the length of a longitudinal direction may be set to 5-10 mm, the said length is the supply speed | rate of the converged filament 1, the cutter blade rotational speed of the pelletizing apparatus 6 It is adjusted by etc.

  The resin pellet in the present invention thus obtained is a thermoplastic resin pellet containing 5 to 10 mm in the longitudinal direction containing conductive fibers, and the length in the longitudinal direction is substantially equal to the fiber length of the conductive fibers. It is a resin pellet.

  The resin pellet in the present invention has a length in the longitudinal direction of 5 to 10 mm. Since the resin pellets are the above-mentioned length, the electromagnetic wave shielding property of the obtained electromagnetic wave shielding molded product is excellent, and molding that does not easily cause cracking even when using a snap-fit structure with an extremely thin portion as a resin nail Goods can be obtained. When the length of the resin pellet is less than 5 mm, the electromagnetic shielding property is lowered and the reinforcing effect of the resin nail portion tends to be lowered. On the other hand, when the length is more than 10 mm, the conductive fiber is gold during injection molding. There is a possibility that the gate portion of the mold is clogged and the moldability is lowered or the meterability is lowered in the injection molding.

  In addition, the length (diameter) of the resin pellet in the short direction is about 1 to 5 mm so that the resin pellet can be stably supplied during injection molding, and the variation in the weight and characteristics of the obtained molded product is reduced. To preferred.

  In addition, the resin pellet in this invention is a resin pellet whose length of a longitudinal direction is substantially equal to the fiber length of an electroconductive fiber. That is, the length of the conductive fiber is the longest fiber length that can be included in the resin pellet supplied in the injection molding. Therefore, in a molded product formed from such resin pellets, conductive fibers having a fiber length longer than the fiber length of the filler are added to the molded product obtained by using the conventional conductive fiber filler. Can be contained. That is, the average fiber length is also long, and particularly characteristically, the maximum fiber length included in the fiber length distribution is relatively long.

  The present invention has a composition other than the above as long as it does not impair the desired properties of the present invention, and conventionally known additives such as flame retardants, flame retardant aids, thermal stabilizers, antioxidants, light stabilizers, Release agents, flow modifiers, colorants, lubricants, foaming agents and the like may be added as necessary. Further, carbon black, metal powder, metal flake, etc. and reinforcing materials and fillers such as glass fiber, glass flake, whisker, aramid fiber, talc, mica, wollastonite, clay, silica, glass powder, etc. may be used in combination. it can.

  The electromagnetic wave shield molded product having a portion of 0.5 mm thickness or less according to the present invention can be obtained by injection molding the resin pellet.

  In the injection molding, the resin pellets may be used as a master batch and blended with other pellets.

  As the injection molding method, it is preferable to use high-speed injection molding and / or injection compression molding which is excellent in moldability.

  However, in order to satisfactorily mold a molded product having a thin portion of 0.5 mm or less, it is preferable to set the injection speed to 250 to 3000 mm / sec, preferably about 700 to 1500 mm / sec. The higher the injection speed, the more suitable it is for easily molding a molded product having a thin portion of 0.5 mm or less. However, if it is 3000 mm / sec or more, there is a possibility that resin burning may occur.

  Furthermore, it is preferable to use an injection compression molding method in order to suppress the orientation of the molded product and to allow the conductive fibers to remain long in a portion having a thickness of 0.5 mm or less. Even in normal injection molding, by selecting the injection conditions, it is possible to have long fibers or the like in the thin-walled part, but if there is a very thin part and the flow length of that part is long, normal injection In molding, there is a possibility that long fibers may not be sufficiently present in a thin portion or the distribution may be non-uniform. In such a case, it is preferable to use an injection compression molding method.

  That is, the injection compression molding method is a method in which a resin composition is filled into a thin portion by injecting a molten resin in a state that is slightly wider than the thickness dimension of a molded product intended for injection molding, and then the mold is clamped. It is a known injection molding method to obtain the desired molded product by doing, but when using the injection compression molding method, in order to inject the mold in advance with the actual thickness of the molded product open, Conductive fibers having a long fiber length can be sufficiently present even in a very thin portion where the molded product is 0.5 mm or less.

  Therefore, in the present invention, it is particularly preferable to use injection compression molding because a large number of long fibers can be present even in an extremely thin portion and the electromagnetic wave shielding property and snap fit property can be improved.

  Thus, the obtained electromagnetic shielding molded product of the present invention requires electromagnetic shielding properties and snap fit properties, and various uses of the electromagnetic shielding molded product having an extremely thin portion, specifically, for example, portable It is preferably used for various types of internal mechanism parts, memory card cases, etc. for equipment casings or portable equipment.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

  The raw materials used in this example are summarized below.

Details of the used thermoplastic resin and filler are as follows.
Resin A: ABS resin (produced by UMGABS) having a polybutadiene content of 21% by mass obtained by the graft-blend method and a mass reduction rate of 1.56% by mass at 300 ° C.
Resin B: ABS resin (manufactured by UMGABS) having a polybutadiene content of 17% by mass obtained by the graft-blend method and a mass reduction rate of 0.6% by mass at 300 ° C.
Resin C: ABS resin (manufactured by UMGABS) having a polybutadiene content of 11% by mass obtained by the graft-blend method and a mass reduction rate of 0.54% by mass at 300 ° C.
Resin D: MBS resin having a polybutadiene content of 70% by mass (product number C223A manufactured by Mitsubishi Rayon Co., Ltd.)
Resin E: Polycarbonate resin (product number 301-22, manufactured by Sumitomo Dow)
Carbon long fiber A: Fiber diameter 7 μm, 12,000 filaments (manufactured by Toho Tenax Co., Ltd.)
Carbon long fiber B: Fiber diameter 7 μm, 24,000 filaments (manufactured by Toho Tenax Co., Ltd.)
-Metal-coated carbon long fiber: Carbon fiber with 7 μm fiber diameter and 6,000 filaments coated with nickel. • Stainless steel long fiber: Stainless fiber with 7 μm fiber diameter and 5000 filaments (Nippon Seisen Co., Ltd.) Made)
・ Carbon single fiber: Chopped fiber (pyrofil made by Mitsubishi Rayon Co., Ltd.) with a fiber diameter of 7.5 μm and an average fiber length of 6 mm
( Reference Example 1)
Resin pellets were produced in the following manner by a long fiber pellet production process equipped with a molten resin supply device, a molten resin impregnation device, a shaping device, a cooling device, and a pelletizing device as shown in FIG.

  That is, the bundled carbon long fibers A having 12,000 filaments were supplied to the resin impregnation apparatus 3. The resin impregnation apparatus 3 includes a single screw extruder as the molten resin supply apparatus 2. The supply amount of the resin A and the supply amount of the carbon long fiber A were supplied so that 80% by mass of the resin A and 20% by mass of the carbon long fiber A were contained in the resin pellet. Next, the molten resin composition impregnated in the thermoplastic resin is solidified by the cooling device 5, then pelletized by the pelletizing device 6, and 80% by mass of an ABS resin (resin A) containing 21% by mass of the polybutadiene component, A resin pellet A having a length in the longitudinal direction and a carbon fiber length of 7 mm consisting of 20% by mass of the carbon long fiber A was obtained.

  Various test pieces were molded using the obtained resin pellet A under the following conditions.

  Preliminary drying of resin pellets: Drying was carried out at 120 ° C. for 5 hours with a hot air circulating dryer.

Injection molding machine: ES600 manufactured by Nissei Plastic Industry Co., Ltd.
Resin temperature: 250 ° C
Mold temperature: 80 ℃
Test piece: 40 × 40 mm, molded product having a thick portion with a thickness of 10 mm and a thickness of 1 mm around a thin portion with a thickness of 0.5 mm (square test piece), and the maximum width between the springs 13 and 13 shown in FIG. Is a molded product with a thickness of 6 mm and the thinnest part of each spring being 0.5 mm (snap fit evaluation test piece)

(Electromagnetic shielding)
Using a 0.5 mm thick portion of the square test piece, a magnetic wave (frequency 800 MHz) was measured using TR-17301A and R3361A manufactured by Advantest Corporation.

(Snap fit)
The snap fit evaluation test piece 14 was molded into 80 shots, and the test piece 14 was inserted into the fitting body 15 having a resin-made insertion portion with a width of 5 mm shown in FIG. The number was counted and evaluated.

(Massability of molding machine)
When 80 shots of the snap fit evaluation test piece molding had a measurement time exceeding 20 seconds and 8 shots or more were generated, the evaluation was evaluated as x.

(Molding defect rate)
The obtained 80 molded products were observed and the number of unfilled products was counted visually.

The results are shown in Table 1.
( Reference Examples 2-12)
Molded articles were obtained and evaluated in the same manner as in Reference Example 1 except that pellets having the composition and shape as shown in Table 1 were used. The results are shown in Table 1.
( Reference Example 13)
A molded product was obtained and evaluated in the same manner as in Reference Example 1 except that the injection speed was set to 700 mm / sec. The results are shown in Table 1.
( Reference Examples 14 and 15 and Examples 1 and 2 )
A molded product was obtained and evaluated in the same manner as in Reference Example 1 except that the injection molding was compression molded and pellets having an injection speed, composition and shape as shown in Table 1 were used. The results are shown in Table 1.

(Comparative Examples 1 to 5 )
A molded product was obtained and evaluated in the same manner as in Reference Example 1 except that the composition, pellet shape, and molding speed described in Table 2 were used. The results are shown in Table 2.

It is a schematic diagram which shows the manufacturing process of the resin pellet in this invention. It is a schematic diagram which shows the fitting body for inserting the snap fit property evaluation test piece and snap fit property evaluation test piece which were used in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Converged filament 2 Molten resin supply apparatus 3 Resin impregnation apparatus 4 Shaping apparatus 5 Cooling apparatus 6 Pelletizing apparatus 7 Resin pellet 8 Fiber / resin composite 13 Spring part 14 Snap-fit test piece 15 Fitting body

Claims (4)

ABS-based resin containing polybutadiene component 15 to 35 wt%, of at least one resin selected from the MBS resins and their modified resins containing 55 to 75 wt%, contains a polycarbonate-based resin 25 to 45 wt% Resin characterized in that it is a resin pellet having a longitudinal length of 5 to 10 mm containing a thermoplastic resin and conductive fibers, and the length in the longitudinal direction is substantially equal to the fiber length of the conductive fibers. An electromagnetic shielding molded product having a portion of 0.5 mm thickness or less obtained by injection compression molding using pellets.   The electromagnetic wave shield molded article according to claim 1, wherein the resin pellets are composed of 70 to 85% by mass of a thermoplastic resin and 15 to 30% by mass of conductive fibers.   The electromagnetic wave shield molded article according to claim 1 or 2, wherein the ABS resin, MBS resin and their modified resins have a mass reduction rate of 3% by mass or less at a temperature increase of 10 ° C / min and a temperature of 300 ° C. . An electromagnetic wave shield molded article, wherein the molded article according to any one of claims 1 to 3 is a portable device casing or an internal mechanism component thereof.

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