JP2009202580A - Electromagnetic wave shield molded product and its manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave shield molded product excellent in molded product outward appearance and molded product strength in addition to electromagnetic wave shielding property, light weight property, moldability, and economy. <P>SOLUTION: The electromagnetic wave shield molded product 10 is made by previously manufacturing a flat plate member 1 made of resin composition reinforced with continued conductive fiber and having an abbreviate plane part, then inserting the flat plate member 1 into an injection molding die, and then integrating a resin frame member 2 made of thermoplastic resin composition reinforced with dispersed reinforced fiber by injection molding in a manner that at least a part of the flat plate member 1 and the resin frame member 2 are made of an oppositely abutting shape and the width of the resin frame member connected in the oppositely abutting shape part is 0.05 to 1.5 mm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention inserts a molded article made of a resin composition reinforced with continuous conductive fibers into an injection mold and then injection-molds a molded article made of a thermoplastic resin composition reinforced with dispersed reinforcing fibers. For example, a personal computer, a mobile phone, a digital camera, a TV, a projector, a game machine, a medical product, other electromagnetic shielding molded products used as parts or casing parts of electric / electronic devices, and the like It relates to a manufacturing method.

  Currently, fiber-reinforced plastics (excellent in moldability, productivity, and economy) are used for parts and housings of electrical and electronic equipment such as personal computers, mobile phones, digital cameras, video cameras, televisions, projectors, game machines, and medical supplies. FRP) is frequently used. Among FRPs, those having excellent conductivity are preferably used because they have high electromagnetic shielding properties.

  However, in recent years, with the spread of electronic devices such as personal computers, mobile phones, digital cameras, game machines, etc., as multi-functions and miniaturization progress, electromagnetic interference from other electronic devices and electromagnetic waves to other electronic devices Interference has become a problem, and its housing is required to have higher electromagnetic shielding properties than ever before. In particular, since the weight reduction is regarded as important in the above applications, the thickness of the housing has been reduced, and the conventional FRP is becoming unable to satisfy the electromagnetic shielding properties.

  As a means for satisfying electromagnetic shielding properties, magnesium alloy die casting and thixomolding have been put into practical use, but there is a problem that it is difficult to cope with complicated shapes and thin shapes. In addition, when a metal material is used, there is a limit to reducing the weight.

  Thus, as disclosed in Patent Document 1, a casing that combines electromagnetic shielding properties and weight reduction is disclosed by using a casing in which a metal plating layer is provided on the surface of a plastic molded product. However, the use of the plating process causes a cost increase and also has a problem in terms of environmental load such as drainage pollution. Patent Document 2 discloses a molded product in which a flat plate member excellent in electromagnetic wave shielding properties and light weight and a resin frame member excellent in moldability and economy are integrated. However, since the shrinkage difference between the flat plate member and the resin frame member is large, a minute and non-uniform crack occurs in the abutting portion between the flat plate member and the resin frame member after integral molding, and the molded product appearance deteriorates or the molded product There was a problem that the strength was weakened.

JP 2000-349486 A JP 2004-140255 A

  The present invention provides an electromagnetic wave shield molded product excellent in molded product appearance and molded product strength in addition to electromagnetic wave shielding properties, lightness, moldability, and economy, and a method for producing the same, in view of the problems of the conventional technology. For the purpose.

The present invention adopts the following configuration in order to achieve the above object. That is,
(1) A thermoplastic resin which is made of a resin composition reinforced with continuous conductive fibers, which is manufactured in advance and is inserted into an injection mold and then reinforced with dispersed reinforcing fibers. An electromagnetic shielding molded product in which a resin frame member made of a composition is integrated by injection molding, wherein at least a part of a joined portion of the flat plate member and the resin frame member has a butted shape, and the butted shape portion The manufacturing method of the electromagnetic wave shield molded product characterized by including the part from which the width | variety of the said resin frame member joined in 0.05-1.5mm is included.
(2) The butt length of the portion where the width of the resin frame member in the butt shape portion is 0.05 to 1.5 mm is 70% or more of the entire butt length of the flat plate member and the resin frame member. The method for producing an electromagnetic wave shield molded article according to (1).
(3) A plurality of through holes are formed in the flat plate member, inserted into an injection mold having a cross-sectional positioning pin 0.02 to 0.5 mm smaller than the size of the through hole, and then dispersed. The method for producing an electromagnetic wave shield molded article according to (1) or (2), wherein a resin frame member made of a thermoplastic resin composition reinforced with fibers is integrated by injection molding.
(4) The manufacturing method of the electromagnetic wave shield molded product according to any one of (1) to (3), wherein the through hole formed in the flat plate member is substantially circular and the inner diameter is 0.5 to 5 mm.
(5) An electromagnetic wave shield molded article produced by any one of the production methods (1) to (4), wherein the thermoplastic resin composition of the resin frame member comprises 25 to 95% by weight of a thermoplastic resin, glass fiber An electromagnetic shielding molded product composed of 5 to 75% by weight.
(6) An electromagnetic wave shield molded article produced by any one of the production methods (1) to (4), wherein the thermoplastic resin composition of the resin frame member comprises 25 to 95% by weight of a thermoplastic resin, carbon fiber An electromagnetic shielding molded product composed of 5 to 75% by weight.
(7) An electromagnetic wave shield molded article produced by the production method of any one of (1) to (4), wherein the molding shrinkage rate of the thermoplastic resin composition of the resin frame member is 0.5% or less. Shield molded product.
(8) The electromagnetic wave shield molded product according to any one of (5) to (7), which is a casing for an electric / electronic device.

  The electromagnetic wave shield molded product of the present invention is excellent in the molded product appearance and molded product strength in addition to the electromagnetic wave shielding property, light weight, moldability and economy, and is used for personal computers, mobile phones, digital cameras and other AV equipment, OA. It is suitable for the housing of equipment.

It is a perspective view of the electronic device housing | casing which is one Example of the electromagnetic wave shield molded product of this invention. It is drawing which defines the width | variety of the resin frame member of this invention. It is drawing explaining one Example of the electromagnetic wave shield molded product of this invention. It is drawing explaining one Example of the electromagnetic wave shield molded product of this invention. It is drawing explaining the comparative example of an electromagnetic wave shield molded product.

  FIG. 1 is a perspective view of an electromagnetic wave shield molded product according to an embodiment of the present invention.

  In FIG. 1, a flat plate member 1 constituting an electromagnetic wave shield molded article 10 of the present invention is made of a resin composition reinforced with continuous conductive fibers. This reinforced form is a state in which continuous fibers of at least 10 mm or more are arranged in at least one direction (UniDirectional: UD) of the molded product, and does not necessarily need to be continuous fibers throughout the molded product. There is no problem even if it is divided by. Examples of specific conductive fiber forms include filaments, cloths, UD cloths, UDs, blades, multifilaments and spun yarns that are arranged in one direction with drum winds, etc. Cross and UD are preferably used from the viewpoint of process. Moreover, these strengthening forms may be used independently or may use 2 or more types of strengthening forms together.

  As the conductive fibers used for the flat plate member 1, for example, metal fibers such as aluminum fibers, brass fibers, and stainless fibers, polyacrylonitrile-based, rayon-based, lignin-based, pitch-based carbon fibers, graphite fibers, and the like are electrically conductive. In addition to fibers exhibiting properties, insulating fibers such as glass fibers, organic fibers such as aramid fibers, PBO fibers, polyphenylene sulfide fibers, polyester fibers, acrylic fibers, nylon fibers, polyethylene fibers, and silicon carbide fibers, silicon Examples thereof include fibers obtained by coating an inorganic fiber such as a nitride fiber with a conductor. As a method for covering the conductor, for example, a metal such as nickel, ytterbium, gold, silver, copper, or aluminum is plated (electrolytic or electroless), CVD, PVD, ion plating, vapor deposition, or the like. A method of covering at least one layer can be exemplified. These conductive fibers may be used alone or in combination of two or more. Among these, carbon fiber, particularly polyacrylonitrile-based carbon fiber is preferably used from the viewpoint of the balance of specific strength, specific rigidity, and light weight, and in particular, at a low cost.

  As a resin component used for the flat plate member 1, both a thermosetting resin and a thermoplastic resin can be used. In the case of a thermosetting resin, the molded product has excellent rigidity and strength, and in the case of a thermoplastic resin, the molded product has excellent impact strength and recyclability. Examples of such thermosetting resins include unsaturated polyesters, vinyl esters, epoxies, phenols (resol type), urea melamine, polyimides, copolymers thereof, modified products, and / or blends of two or more. Resin or the like can be used. Furthermore, an elastomer or a rubber component may be added to the thermosetting resin in order to improve impact resistance.

  Examples of the thermoplastic resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polyester such as liquid crystal polyester, and polyethylene (PE). In addition to polyolefins such as polypropylene (PP) and polybutylene, and styrene resins, polyoxymethylene (POM), polyamide (PA), polycarbonate (PC), polymethylene methacrylate (PMMA), polyvinyl chloride (PVC), polyphenylene Sulfide (PPS), polyphenylene ether (PPE), modified PPE, polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polysulfone (PSU), modified P U, polyethersulfone, polyketone (PK), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyarylate (PAR), polyethernitrile (PEN), phenolic resin , Fluororesins such as phenoxy resin and polytetrafluoroethylene, thermoplastic elastomers such as polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, polyisoprene, fluorine, etc. It may be a polymer, a modified product, and / or a resin blended with two or more types. Furthermore, in order to improve impact resistance, a resin obtained by adding another elastomer or rubber component to the thermoplastic resin may be used.

  The proportion of continuous conductive fibers in the resin composition constituting the flat plate member 1 is preferably 20 to 90% by volume, more preferably 30 to 80% by volume from the viewpoints of moldability, mechanical properties, and electromagnetic wave shielding properties.

  Further, in order to adapt the electromagnetic wave shield molded article 10 of the present invention to the housing shape of an electric / electronic device, it is desirable that the flat plate member 1 has at least one substantially flat portion. More preferably, 50% or more of the surface having the largest area forms a substantially flat surface.

  Similarly, assuming the case of an electric / electronic device, from the viewpoint of thinness and lightness, the average thickness of the flat plate member 1 is preferably 1.6 mm or less, more preferably 1.4 mm or less. .2 mm or less is more preferable, and 1.0 mm or less is particularly preferable. Here, the average thickness of the flat plate member 1 is an average value of measured values of at least five points that are evenly distributed in the substantially planar portion. In the measurement of the average thickness, parts intentionally imparted with a shape such as a rib part, a hinge part, and a convex / concave part are excluded.

  The projected area of the flat plate member 1 is not particularly limited as long as it is a size that can be adapted to the electromagnetic wave shield molded product 10, but from the viewpoint of further improving the electromagnetic wave shielding property when integrated, it conforms to the size of the top surface of the housing. preferable. In particular, when it is assumed to be used for a casing of a notebook personal computer, 200 cm 2 or more is preferable, 400 cm 2 or more is more preferable, and 600 cm 2 or more is particularly preferable. Here, the projected area is a scale representing the size of the molded product surface obtained from the outer dimensions of the molded product. The projected area of the flat plate member is obtained by placing the flat plate member gently on the surface plate, developing a photograph taken from a direction perpendicular to the surface plate, and measuring the area occupied by the flat plate member.

  Next, the resin frame member 2 constituting the electromagnetic wave shield molded article 10 according to the present invention is made of a thermoplastic resin composition reinforced with dispersed reinforcing fibers as described above.

  Reinforcing fibers used for the resin frame member 2 include polyacrylonitrile-based, rayon-based, lignin-based, pitch-based carbon fibers, graphite fibers, glass fibers, aluminum fibers, brass fibers, stainless fibers, and other metal fibers, silicon cars Examples thereof include inorganic fibers such as bite fibers and silicon nitride fibers, and may also be fibers obtained by coating these fibers with a conductor. These reinforcing fibers may be used alone or in combination of two or more. Among these, glass fiber and carbon fiber are preferably used from the viewpoint of the balance of specific strength, specific rigidity, and lightness. For example, when it is necessary to transmit radio waves locally even after integration, such as an antenna portion of a casing on the display side of a notebook personal computer, it is preferable to use glass fibers having a large electric resistance at the corresponding portions. When it is necessary to maintain high electromagnetic shielding properties even after integration, it is preferable to use carbon fibers having a low electrical resistance.

  There is no restriction | limiting in particular as a thermoplastic resin used for the resin frame member 2, The resin illustrated by the thermoplastic resin used for the flat plate member 1 can be used. In particular, PPS resin is used from the viewpoint of heat resistance and chemical resistance, polycarbonate resin and styrene resin are used from the viewpoint of molded product appearance and dimensional stability, and polyamide resin is used from the viewpoint of strength and impact resistance of the molded product. More preferably used. Further, from the viewpoint of reducing peeling from the flat plate member 1 and warping of a molded product caused by a dimensional difference due to shrinkage of the resin frame member 2, polycarbonate resin and polyphenylene ether resin are preferable.

  In the thermoplastic resin composition constituting the resin frame member 2, the reinforcing fibers are uniformly dispersed in the thermoplastic resin. From the viewpoint of balance between moldability, strength, and lightness, a preferable composition is a thermal resin. The plastic resin content is 25 to 95% by weight, more preferably 35 to 85% by weight, carbon fiber 5 to 75% by weight, and still more preferably 15 to 65% by weight.

  Further, the fiber length of the reinforcing fiber dispersed is not particularly limited, but the fiber length is preferably long in order to efficiently develop the strength of the reinforcing fiber. From the viewpoint of balance with moldability, the number average fiber length in the range of 100 to 1000 μm is preferably used. Here, the number average fiber length is measured by randomly extracting at least 400 reinforcing fibers dispersed from the resin frame member 2 at an optical microscope or scanning electron microscope up to 1 μm in length. And measuring the average length by calculating the average length. As a method for extracting the reinforcing fibers, a part of the resin frame member 2 is cut out, sufficiently dissolved with a solvent for dissolving the resin component, and then separated from the reinforcing fibers by an operation such as filtration. However, regarding the position where the molded product is cut out, the periphery of the weld, the periphery of the gate, the rib portion, the hinge portion, and the end of the molded product are avoided.

  Furthermore, the thermoplastic resin constituting the resin frame member 2 may contain other fillers and additives within a range that does not impair the object of the present invention, depending on required characteristics. For example, inorganic fillers, flame retardants, conductivity imparting agents, crystal nucleating agents, ultraviolet absorbers, antioxidants, vibration damping agents, antibacterial agents, insect repellents, deodorants, anti-coloring agents, heat stabilizers, release agents , Antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, antifoaming agents, coupling agents and the like.

  The method of dispersing the reinforcing fibers in the thermoplastic resin in the resin frame member 2 is not particularly limited, and for example, the resin frame member 2 can be manufactured by a method such as melt-kneading the thermoplastic resin and the reinforcing fibers.

  The molding shrinkage rate of the thermoplastic resin composition constituting the resin frame member 2 is preferably 0.5% or less. Here, the molding shrinkage rate of the thermoplastic resin composition was determined by measuring molding shrinkage in the flow direction and the flow perpendicular direction when an 80 × 80 × 1 t square plate was molded with an injection mold having a film gate. The average value of the direction is calculated. When the resin frame member 2 is composed of a thermoplastic resin composition having a molding shrinkage rate exceeding 0.5%, warpage or peeling due to the shrinkage of the resin frame member 2 during injection molding is likely to occur. In order to suppress the occurrence of such defects, strict control of injection molding conditions is required, and productivity is lowered.

  As described above, the thermoplastic resin composition is melted and kneaded in the thermoplastic resin composition selected from the viewpoint of reducing peeling from the flat plate member 1 and warping of the molded product, thereby cooling the thermoplastic resin composition in the cooling step during molding. Since the reinforcing fiber becomes a resistance force against the force to be shrunk, the effect of suppressing the molding shrinkage can be obtained. In particular, when the thermoplastic resin composition and the reinforcing fiber are kneaded at the above-described ratio, the molding shrinkage of the thermoplastic resin composition can be suppressed particularly well.

  The electromagnetic wave shield molded product 10 of the present invention is characterized in that the flat plate member 1 is manufactured in advance and inserted into an injection mold, and then the resin frame member 2 is integrated by injection molding.

  Here, the manufacturing method of the flat plate member 1 is not particularly limited, and is a hand lay-up molding method, a spray-up molding method, a vacuum back molding method, a pressure molding method, an autoclave molding method, a press molding method, a transfer method. Examples thereof include a method using a thermosetting resin such as a molding method, and a method using a thermoplastic resin such as a press molding and a stamping molding method. In particular, from the viewpoint of processability and mechanical properties, a vacuum back molding method, a press molding method, a transfer molding method and the like are preferably used.

  Further, from the viewpoint of maintaining the form of the electromagnetic wave shield molded product 10 even after integration, it is preferable that a portion of the surface of the flat plate member 1 has an adhesive layer at a portion where the resin frame member 2 is joined. It is preferable to have an adhesive layer on at least a part of the joint surface between the flat plate member 1 and the resin frame member 2, more preferably to have an adhesive layer on 50% or more of the joint surface area. It is more preferable to have an adhesive layer over 70% of the area, and it is particularly preferable to have an adhesive layer over the entire bonding surface. Here, the adhesive layer may be composed of components different from the flat plate member 1 or the resin frame member 2 such as an adhesive, or may be composed of components of the flat plate member 1 or the resin frame member 2 such as a welded layer. May be.

  Assuming that the joint between the flat plate member 1 and the resin frame member 2 is used in a housing for electric / electronic equipment, the appearance surface 10a side is not a fitting surface but a fitting surface from the viewpoint of thinning and design. It is necessary to be joined in a butt shape inside.

  FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1, and is an example showing a butt shape of the flat plate member 1 and the resin frame member 2. In each of the five cross-sectional views (a) to (e), the upper side of each cross-sectional view is the surface 10a side of the electromagnetic wave shield molded product 10, and the right side of each cross-sectional view is the end of the electromagnetic wave shield molded product 10, that is, the resin frame member 2 The left side of each sectional view is the center side of the electromagnetic wave shield molded product 10. The lower side of each cross-sectional view is not the appearance surface 10a, but a rib or the like that extends the resin frame member 2 toward the center is formed in order to increase the adhesive force between the flat plate member 1 and the resin frame member 2, or other parts are assembled. For example, a boss shape or the like can be formed.

  In the present invention, the butt shape means that the back surface 1a and the end surface 1b of the flat plate member 1 are fixed by the resin frame member 2 without fitting the resin frame member 2 to the appearance surface 10a of the electromagnetic wave shield molded product 10. Is. Here, the protruding end of the resin frame member 2 raised up to the appearance surface 10a is referred to as a convex portion 2a.

  The appearance surface 10a of the electromagnetic wave shield molded product 10 is such that the convex portion 2a of the resin frame member 2 protrudes in a convex shape with respect to the substantially flat surface formed by the flat plate member 1, that is, the convex portion 2a is higher than the appearance surface 10a. If so, the resin may spread so as to fit a part of the appearance surface 10a. In this case, the entire electromagnetic wave shield molded article 10 cannot be thinned, and the convex portion 2a of the resin frame member 2 does not have a uniform shape, which is not a preferable aspect in terms of design.

  On the other hand, when the convex portion 2a of the resin frame member 2 is lower than the appearance surface 10a, that is, when the end surface 1b of the flat plate member 1 is exposed, a gap between the flat surface member 1 and the resin frame member 2 is caused by the variation in dimensions. This is not a preferable mode because the electromagnetic wave shield molded product 10 is insufficient in strength and has poor design.

  On the other hand, when the appearance surface 10a and the convex part 2a of the resin frame member 2 are joined in a butting shape so as to form substantially the same plane, both the thickness reduction and the design of the electromagnetic wave shield molded product 10 can be achieved. Can be satisfied.

  As shown in FIG. 2A, the width of the resin frame member 2 joined at the butted shape portion refers to a length corresponding to the width of the convex portion 2a of the resin frame member 2, and is 0.05 to It is desirable to include a portion that is 1.5 mm. When the width of the resin frame member 2 is less than 0.05 mm, it becomes difficult to fill the injection molding resin forming the resin frame member 2 and short shots are generated, or molding conditions are set in the overfill direction to suppress short shots. It becomes necessary to set the burrs and other parts will be burred. When the width of the resin frame member 2 exceeds 1.5 mm, the shrinkage amount of the resin frame member 2 after injection molding increases, so that minute and non-uniform cracks occur at the butt portion, and the appearance of the molded product is deteriorated. The strength of the molded product is weakened. On the other hand, if the width of the resin frame member 2 is set to 0.05 to 1.5 mm, molding defects such as short shots can be minimized and occurrence of cracks can be suppressed.

  Here, the width of an arbitrary point of the resin frame member 2 is a length in which a straight line passing through the two points of the point and the perpendicular foot from the point to the butt surface intersects the resin frame member 2. The width of the resin frame member 2 having various shapes is illustrated as shown in FIG. In order to achieve the object of the present invention to avoid the deterioration of the appearance of the molded product and the decrease in the strength of the molded product due to minute cracks at the butted portion, the width of the resin frame member 2 joined at the butted shape portion is 0.05 to The butt length of the portion of 1.5 mm is preferably 70% or more of the total butt length of the flat plate member 1 and the resin frame member 2, more preferably 90% or more, and 100%. Is particularly preferred.

  The resin frame member selected from the viewpoint of suppressing molding defects such as short shots and the shrinkage amount of the resin frame member 2 as described above when the bonding surface between the flat plate member 1 and the resin frame member 2 has an adhesive layer. By setting the width to 2, the adhesion between the flat plate member 1 and the resin frame member 2 becomes stable and strong. Furthermore, if the adhesive force between the flat plate member 1 and the resin frame member 2 is strong, the flat plate member 1 becomes a resistance force against molding shrinkage when the resin frame member 2 is formed by injection molding. An effect of reducing warpage of the electromagnetic wave shield molded product can be obtained.

  The butting length of the flat plate member 1 and the resin frame member 2 refers to the total length of the outer periphery of the flat plate member 1 that can be butted against the resin frame member 2. For example, when the butt-shaped resin frame member 2 is provided over the entire periphery of the substantially rectangular flat plate member 1 as shown in FIG. 1, the butt length between the flat plate member 1 and the resin frame member 2 is the same as that of the flat plate member 1. Refers to the total length of the four sides.

  When the butt length of the portion where the width of the resin frame member 2 joined at the butt shape portion is less than 0.05 mm exceeds 30% of the entire butt length of the flat plate member 1 and the resin frame member 2, at the time of injection molding Since it becomes difficult to fill the gap of less than 0.05 mm with the injection molding resin, the above-described short shot is likely to occur. In order to suppress the occurrence of such defects, strict control of injection molding conditions is required, and productivity is lowered.

  On the other hand, if the width of the resin frame member 2 bonded at the butt-shaped portion is 1.5 mm or more, the resin frame member 2 is greatly contracted after injection molding, and peeling occurs at the boundary with the flat plate member 1. Strength may be reduced. Furthermore, when such peeling occurs, the design is impaired, which is not preferable. When the butt length of the portion where the width of the resin frame member 2 joined at the butt shape portion is 1.5 mm or more exceeds 30% of the total butt length of the flat plate member 1 and the resin frame member 2, the strength of the product is as follows. Since the width of the resin frame member 2 is wide even to necessary portions, there is a risk that product defects frequently occur. Furthermore, even at the time of injection molding, the resin is not sufficiently filled in a width portion of 1.5 mm or more, and cracks are generated or a resin flow is developed. Conversely, when the injection molding pressure is increased, burrs may occur in narrow portions.

  On the other hand, the butt length of the portion where the width of the resin frame member 2 joined at the butt shape portion is 0.05 to 1.5 mm is 70% or more of the entire butt length of the flat plate member 1 and the resin frame member 2. In this case, since it becomes easy to uniformly fill the injection molding resin, it is difficult to generate a short shot and the flexibility of molding conditions can be expanded. That is, the degree of freedom in product design is expanded, and it is possible to cope with required specifications for various shapes.

  The resin frame member 2 is formed by filling a gap between the flat plate member 1 and the injection mold when the flat plate member 1 is inserted into the injection mold. In order to control the width of the resin frame member 2 to 0.05 to 1.5 mm, it is easy to set the flat plate member 1 at a predetermined position of the injection mold, and the flat plate member is caused by the resin pressure during the injection molding. It is preferable to provide both the flat plate member 1 and the injection mold with a positioning mechanism that makes it easy to suppress blurring of the first plate. For example, through holes are formed at predetermined two to three positions of the flat plate member 1, the same number of positioning pins are arranged at the corresponding positions of the injection mold, and the positioning pins are passed through the holes of the flat plate member 1. The method of inserting is illustrated. The size of the cross section of the positioning pin of the injection molding die is preferably 0.02 to 0.5 mm smaller than the size of the through hole of the flat plate member 1 in both length and width. When the difference in size between the positioning pin and the through hole of the flat plate member 1 is less than 0.02 mm, in order for all the positioning pins of the injection mold to pass through the through hole of the flat plate member 1 smoothly, Strict control over the accuracy of the position is required. In addition, when the difference in size between the positioning pin and the through hole of the flat plate member 1 exceeds 0.5 mm, the flat plate member 1 centering on the through hole is likely to be displaced when a resin pressure is applied during injection molding. In order to keep the gap between the flat plate member 1 and the injection mold at 0.05 to 1.5 mm, it is necessary to strictly control the molding conditions such as the injection speed. On the other hand, when the size of the cross section of the positioning pin of the injection molding die is 0.02 to 0.5 mm smaller than the size of the through hole of the flat plate member 1 both vertically and horizontally, a drill is applied to the previously formed flat plate member 1. It is possible to set the flat plate member 1 at a predetermined position of the injection molding die by forming a through hole by a method such as making a hole by inserting the positioning pin provided in the injection molding die. It becomes easy, and it becomes easy to suppress blurring of the flat plate member 1 due to the resin pressure at the time of injection molding. Although there is no restriction | limiting in particular about the shape of the through hole provided in the flat plate member 1, From a viewpoint of productivity, it is preferable that it is circular. The diameter of the circle is not particularly limited, but is preferably 0.5 mm or more from the viewpoint of the durability of the positioning pin of the injection mold having a diameter smaller than the through hole, and the strength of the flat plate member 1 and the electromagnetic wave shield It is preferable that it is 5 mm or less from a viewpoint which does not impair property.

  The electromagnetic wave shield molded product 10 of the present invention configured by such a method not only provides light weight that cannot be realized by integration with a metal material, but also a molded product due to minute cracks at the butt portion, which was a problem of the prior art. It also solves the deterioration of the appearance and the strength of the molded product.

  In addition, the manufacturing method of the electromagnetic wave shield molded product 10 of this invention is not limited by these illustrated construction methods and specific examples.

  There is no restriction | limiting in particular in the shape of the electromagnetic wave shield molded article 10, You may have a curved surface, a rib, a hinge, a boss | hub, and a hollow part. The molded product may be subjected to surface decoration treatment by plating, painting, vapor deposition, insert, stamping, laser irradiation, or the like.

  Applications of the electromagnetic wave shield molded product 10 include, for example, a personal computer, a mobile phone, a portable information terminal, a digital camera, a video camera, a television, a projector, a game machine, a facsimile, a compact disc player, a portable MD, a portable radio cassette, an audio In addition to parts and casings for optical equipment, air conditioners, lighting equipment, medical supplies, and other electrical and electronic equipment, electrical components for automobiles and aircraft, internal parts, and the like.

  In particular, the electromagnetic wave shield molded article 10 of the present invention is suitable for a casing for an electric / electronic device or an external member by taking advantage of its excellent electromagnetic wave shielding property, and further, a notebook which requires a thin and wide projection area. It is suitable as a housing for a personal computer or a portable information terminal. When used as such a housing, it is preferable that the flat plate member 1 constitutes at least a part of the top surface of the housing from the viewpoint of electromagnetic shielding properties which is an object of the present invention, and is 50% or more of the projected area of the top surface. Is more preferable, and 70% or more of the projected area of the top surface is particularly preferable.

<Flat plate member and resin frame member>
The flat plate member and the resin frame member will be described.
6 layers of TORAYCA prepreg P9052F-15 (manufactured by Toray Industries, Inc., reinforcing fiber: carbon fiber, base resin: epoxy) are laminated as an outermost layer as an adhesive layer, a polyamide layer CM4000 (a terpolymerized polyamide resin manufactured by Toray Industries, Inc., polyamide) 6/66/610) laminated one layer after press molding (flat plate mold, thickness 0.85 mm, mold temperature 150 ° C., pressure 2.5 MPa, curing time 30 minutes) 199.6 mm × 299.6 mm A diameter of 2.50 mm centered on two predetermined points (two points on a line segment connecting two midpoints of short sides and at a distance of 50 mm from the midpoint of the line segment) A flat plate member was obtained by drilling two circular through holes.

As the resin frame member, short fiber glass fiber reinforced pellets TCP1206-G50 (manufactured by Toray Industries, Inc., glass fiber 50% by weight, base resin: polyamide) was used.
<Injection molding>
The injection mold has a hollow portion with a projected area of 200.0 mm × 300.0 mm, and is on two predetermined lines (a line segment connecting two midpoints of short sides, from the midpoint of the line segment) Two cylindrical positioning pins having a diameter of 2.45 mm centering on two points at a distance of 50 mm were arranged. Attach an injection mold to a 350 ton injection molding machine (J350EIISP, cylinder diameter: φ46mm, screw used: general-purpose full flight type) manufactured by Nippon Steel, Ltd., insert the flat plate member into the injection mold, Heated to about 75 ° C. The pellet TCP 1206-G50 was melted in the range of 280 to 290 ° C. and injection molded at an injection pressure of about 150 MPa to form the resin frame member 2, whereby the electromagnetic wave shield molded product 10 was obtained.

For each of the examples and comparative examples, the ratio of the width of the portion having a butted shape and the length of the butted portion having a width of 0.05 to 1.5 mm among the resin frame members are summarized in Table 1 described later. .
<Evaluation method>
(1) Visual inspection A visual inspection was performed to determine whether peeling or cracking occurred at the butted portion between the flat plate member and the resin frame member.
(2) Surface roughness Using a surface roughness measuring instrument “Surfcoder SE-2300” (manufactured by Kosaka Laboratory Ltd.), trace the shape of the surface of the flat plate member to the butted portion to the resin frame member in the height direction. The contour shape was output at a magnification of 50 and the presence or absence of cracks was evaluated.
(3) Strength Using a precision universal testing machine Autograph AG-10TA (manufactured by Shimadzu Corporation), using an indenter having a square tip shape of 0.2 mm × 0.2 mm, a resin frame member near the butt portion The presence or absence of cracks was evaluated by applying a load up to 50 N at a test speed of 5 mm / min.
(4) Evaluation results Table 1 shows the results of evaluation for each of (1) to (3). Table 1 shows ◯ when no cracks occurred and × when cracks occurred. (3) When cracks occurred in terms of strength, the load at the time of crack occurrence was also described.

  From the results of Examples and Comparative Examples shown in Table 1, the following became clear. The electromagnetic wave shield molded products shown in Examples 1 to 4 are excellent in molded product appearance and molded product strength in addition to electromagnetic wave shielding properties, light weight, moldability, and economy, and as a housing for electrical and electronic devices. It was suitable. In the electromagnetic wave shield molded products shown in Examples 5 and 6, although cracks could not be found from the visual inspection and the evaluation results of the surface roughness, the results of the strength evaluation were inferior to the products of Examples 1 to 4. It was.

  On the other hand, in the molded products of Comparative Examples 1 to 3, the appearance of the molded product and the strength of the molded product were insufficient, and the molded products were insufficient to meet strict demands such as housing use for electric / electronic devices.

  The electromagnetic wave shield molded product of the present invention is suitable as a casing of a notebook personal computer, a portable information terminal, etc., but its application range is not limited to these, but a digital camera, video camera, television, projector, game Machines, facsimiles, compact disc players, portable MDs, portable radio cassettes, audio, optical equipment, air conditioners, lighting equipment, medical supplies, other electrical and electronic equipment parts and housings, automobile and aircraft electrical components, interior It can also be used for parts.

DESCRIPTION OF SYMBOLS 1: Flat plate member 1a: Back surface 1b: End surface 2: Resin frame member 2a: Convex part 10: Electromagnetic wave shield molded product 10a: Appearance surface

Claims (8)

It consists of a resin composition reinforced with continuous conductive fibers, and is manufactured from a thermoplastic resin composition reinforced with dispersed reinforcing fibers after a flat plate member having a substantially flat portion is manufactured in advance and inserted into an injection mold. An electromagnetic wave shield molded product in which the resin frame member is integrated by injection molding, wherein at least a part of the joint portion between the flat plate member and the resin frame member has a butted shape and is joined at the butted shape portion. A method for producing an electromagnetic wave shield molded product comprising a portion in which the width of the resin frame member is 0.05 to 1.5 mm. The butt length of the portion where the width of the resin frame member in the butt shape portion is 0.05 to 1.5 mm is 70% or more of the entire butt length of the flat plate member and the resin frame member. 2. A method for producing an electromagnetic wave shield molded article according to 1. A plurality of through holes are formed in a flat plate member, and inserted into an injection mold having a cross-sectional positioning pin 0.02 to 0.5 mm smaller than the size of the through hole, and then reinforced with dispersed reinforcing fibers. The manufacturing method of the electromagnetic wave shield molded article of Claim 1 or 2 formed by integrating the resin frame member which consists of the made thermoplastic resin composition by injection molding. The manufacturing method of the electromagnetic wave shield molded article in any one of Claims 1-3 whose through-hole formed in a flat plate member is substantially circular, and an internal diameter is 0.5-5 mm. It is an electromagnetic wave shield molded article manufactured with the manufacturing method in any one of Claims 1-4, Comprising: The thermoplastic resin composition of a resin frame member is 25-95 weight% of thermoplastic resins, 5-75 weight% of glass fibers. An electromagnetic shielding molded product composed of It is an electromagnetic wave shield molded article manufactured with the manufacturing method in any one of Claims 1-4, Comprising: The thermoplastic resin composition of a resin frame member is 25-95 weight% of thermoplastic resins, 5-75 weight% of carbon fibers. An electromagnetic shielding molded product composed of An electromagnetic wave shield molded article produced by the production method according to any one of claims 1 to 4, wherein a molding shrinkage of the thermoplastic resin composition of the resin frame member is 0.5% or less. The electromagnetic wave shield molded article according to any one of claims 5 to 7, which is a casing for an electric / electronic device.

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