Electromagnetic wave shielding housing and its manufacturing method, resin housing covering sheet and laminated sheet

Abstract

The present invention provides a resin case covering sheet, a laminate sheet, and an electromagnetic wave shielding case having the electromagnetic wave shielding layer, which can improve wrinkles and breakage and form an electromagnetic wave shielding layer with excellent electromagnetic wave shielding properties, and a method for producing the same. [Solution] A resin casing covering sheet for forming the electromagnetic shielding layer 3 of an electromagnetic shielding casing 10 comprising a resin casing 1 and an electromagnetic shielding layer 3, wherein the problems are solved by: (i) subjecting the sheet at room temperature to a temperature of Tg to Tg+40°C and measuring at said temperature at a tensile speed of 50 mm / min, the breaking elongation being 100 to 1500%, (ii) subjecting the sheet at room temperature to a temperature of Tg to Tg+40°C and measuring at said temperature at a tensile speed of 1000 mm / min, the breaking elongation being 50 to 1200%, and (iii) subjecting the sheet to a puncture strength per unit film thickness at 23°C, measured in a puncture test in accordance with JIS Z1707, being 5 to 150 N / mm.

Description

[Technical field]

[0001] The present disclosure relates to an electromagnetic wave shielding housing and a manufacturing method thereof, and also to a resin housing covering sheet and a laminate sheet. [Background technology]

[0002] Housings for electronic components mounted in vehicles, etc., are required to be lightweight and have electromagnetic shielding properties. For example, a housing made of resin coated with an electromagnetic wave shielding layer has attracted attention.

[0003] As a sheet for forming an electromagnetic wave shielding layer on a resin housing, for example, Patent Document 1 discloses an in-mold transfer molding film having electromagnetic wave shielding properties. The average molecular weight of the resin contained in the film is 5,000 or more and less than 10,000. Patent Document 2 discloses a copper-polyimide laminate having rolled copper foil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2023 / 243290 [Patent Document 2] JP 2013-146870 A Summary of the Invention [Problem to be solved by the invention]

[0005] As a method for attaching a film to a three-dimensional shape, for example, the TOM (Three Dimension Overlay Method) method is known. The TOM method can cover so as to follow the uneven shape, and can impart various functions such as decorativeness and insulation, so it is used for decorative applications such as interior parts of automobiles. Since the TOM method is suitable for covering three-dimensional shapes, it is also promising as a method for covering a resin housing with an electromagnetic shielding layer. However, it is difficult to give a film both electromagnetic shielding properties and extensibility at the same time, and covering defects such as wrinkles and breaks in the electromagnetic shielding layer are likely to occur. Covering defects not only lead to poor appearance, but also to quality and performance deterioration. In other words, the shielding properties of the electromagnetic shielding layer may be reduced. These problems may become more serious due to the trend toward lighter, thinner, shorter, and smaller products. In addition, if the positional deviation of the electromagnetic shielding layer can be prevented, it will be possible to cover only the areas that need covering. Furthermore, it is expected that versatility will be significantly improved. Although the above has been described as a problem with TOM molding, similar issues can arise in vacuum molding, pressure molding, vacuum and pressure molding, press molding, injection molding, and the like.

[0006] The present disclosure has been made in consideration of the above problems, and an object of the present disclosure is to provide a resin housing covering sheet, a laminated sheet, and an electromagnetic wave shielding housing having the electromagnetic wave shielding layer, which can improve wrinkles and breakage and form an electromagnetic wave shielding layer with excellent electromagnetic wave shielding properties, and a method for manufacturing the same. [Means for solving the problem]

[0007] As a result of extensive investigations, the present inventors have found that the problems of the present disclosure can be solved in the following aspect, and have thus completed the present disclosure. [1]: A plastic housing covering sheet for forming an electromagnetic wave shielding layer of an electromagnetic wave shielding housing, the electromagnetic wave shielding layer including a plastic housing and an electromagnetic wave shielding layer covering at least a part of the plastic housing, (i) the resin housing covering sheet at room temperature is placed in a temperature range of Tg to Tg+40°C of the resin housing covering sheet, and the breaking elongation measured at the temperature and at a tensile speed of 50 mm / min is 100 to 1500%, (ii) the resin housing covering sheet at room temperature is placed in a temperature range of Tg to Tg+40°C of the resin housing covering sheet, and the breaking elongation measured at said temperature and at a tensile speed of 1000 mm / min is 50 to 1200%, and further (iii) The resin-casing covering sheet has a puncture strength α per unit film thickness at 23° C. measured in a puncture test in accordance with JIS Z1707 of 5 to 150 N / mm. [2]: The plastic housing covering sheet at room temperature is subjected to an arbitrary measurement temperature T M The temperature measured is T M Young's modulus E measured at a tensile speed of 50 mm / min 50 and the measured temperature T M Young's modulus E measured at a tensile speed of 1000 mm / min 1000 E 1000 / E 50 The resin casing covering sheet according to [1], wherein the refractive index is 0.7 or more. [3]: Contains a thermosetting resin and a curable compound; The curable compound is The resin housing covering sheet according to [1], which contains a curable compound (c) having a hydroxyl group, a secondary amino group, or a tertiary amine group, and having a di- or higher-functional epoxy group. [4]: A laminate sheet comprising a support layer and the resin casing covering sheet according to [1]. [5]: The laminate sheet according to [4], having a release layer between the support layer and the resin housing covering sheet. [6]: When the Tg of the support layer is Tg2 and the Tg of the resin housing covering sheet is Tg1, |Tg2-Tg1|≦100℃ The laminate sheet according to [4], wherein: [7]: An electromagnetic wave shielding housing comprising a resin housing and an electromagnetic wave shielding layer covering at least a portion of the resin housing, The electromagnetic wave shielding casing, wherein the electromagnetic wave shielding layer is a layer formed using the resin casing covering sheet according to any one of [1] to [3]. [8]: A method for manufacturing an electromagnetic wave shielding housing including a resin housing and an electromagnetic wave shielding layer covering at least a portion of the resin housing, comprising: A coating process for forming the electromagnetic wave shielding layer using the resin housing covering sheet according to any one of [1] to [3], A method for producing an electromagnetic shielding housing, wherein the covering step is carried out by any one of a TOM method, a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a press forming method, and an injection molding method. [9]: A method for manufacturing an electromagnetic wave shielding housing including a resin housing and an electromagnetic wave shielding layer covering at least a portion of the resin housing, comprising: a coating step of forming the electromagnetic wave shielding layer using the laminate sheet according to any one of [4] to [6]; and removing layers of the laminated sheet other than the electromagnetic wave shielding layer after the covering step, A method for producing an electromagnetic shielding housing, wherein the covering step is carried out by any one of a TOM method, a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a press forming method, and an injection molding method. Effect of the Invention

[0008] The present disclosure has the excellent effect of providing a resin housing covering sheet, a laminate sheet, and an electromagnetic wave shielding housing having the electromagnetic wave shielding layer, which can improve wrinkles and breakage and form an electromagnetic wave shielding layer with excellent electromagnetic wave shielding properties, and a method for manufacturing the same. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of an electromagnetic wave shielding housing according to the first embodiment. [Diagram 2] FIG. 1 is a schematic cross-sectional view showing an example of a resin housing covering sheet according to a first embodiment. [Diagram 3] 3A to 3C are schematic cross-sectional views showing an example of a manufacturing process of the first embodiment. [Figure 4] 3A to 3C are schematic cross-sectional views showing an example of a manufacturing process of the first embodiment. [Diagram 5] 3A to 3C are schematic cross-sectional views showing an example of a manufacturing process of the first embodiment. [Figure 6] FIG. 6 is a schematic cross-sectional view showing an example of a resin housing covering sheet according to a second embodiment. [Figure 7] 11A to 11C are schematic cross-sectional views showing an example of a laminate sheet according to a third embodiment and a manufacturing process thereof. [Figure 8] FIG. 11 is a schematic cross-sectional view showing an example of a laminate sheet according to a fourth embodiment. [Figure 9] 9 is a cross-sectional view taken along line IX-IX of FIG. 8 . [Figure 10] FIG. 13 is a schematic cross-sectional view showing an example of an electromagnetic wave shielding housing according to a fifth embodiment. [Figure 11] FIG. 13 is a schematic top view showing an example of a laminate sheet according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An example of an embodiment to which the present disclosure is applied will be described below. Each embodiment can be combined in any way. The size and ratio of each member in the following figures are for convenience of explanation and are not limited thereto. In addition, in the present specification, the description of "any number A to any number B" includes the number A as the lower limit and the number B as the upper limit in the range. In addition, the sheet and the film are synonymous. Furthermore, the numerical values ​​specified in this specification are values ​​obtained by the method disclosed in the embodiment or example. In addition, each component may be used alone or in combination of two or more types, unless otherwise specified.

[0011] 1. First embodiment 1-1.Electromagnetic shielding case 1 shows an example of a schematic cross-sectional view of an electromagnetic wave shielding housing according to a first embodiment of the present disclosure. The electromagnetic wave shielding housing refers to a housing in which a plastic housing is covered with an electromagnetic wave shielding layer. As shown in the figure, the electromagnetic wave shielding housing 10 of the first embodiment includes a plastic housing 1 and an electromagnetic wave shielding layer 3 formed so as to cover at least a part of the plastic housing 1.

[0012] The resin housing 1 can be selected arbitrarily as long as it can withstand the molding process for each application. Since it can block electromagnetic waves, it is suitable for use as a resin housing in which electronic components are housed or mounted. The resin housing is used as a part of an article or structure. Examples of resin housings include interior and exterior components for automobiles and exterior components for mobile devices.

[0013] The electromagnetic wave shielding layer 3 is provided over the entire upper surface and side surfaces of the plastic housing 1. The electromagnetic wave shielding layer 3 is formed using the plastic housing covering sheet of the present disclosure (hereinafter also referred to as the present covering sheet). There is no limitation on the method for forming the electromagnetic wave shielding layer 3 from the present covering sheet, but any one of the following three-dimensional surface covering methods is suitable: TOM (Three Dimension Overlay Method) molding, vacuum molding, pressure molding, vacuum pressure molding, press molding, and injection molding. Among these, the present covering sheet is particularly suitable for TOM molding.

[0014] The electromagnetic shielding layer 3 is formed of a single layer or multiple layers. The electromagnetic shielding layer 3 has, for example, a conductive material therein and shields electromagnetic waves. The electromagnetic shielding layer 3 may further include a non-shielding layer having other functions according to needs. Examples of the non-shielding layer include an insulating layer, a heat conductive layer, a waterproof layer, a shielding layer, a colored layer, a flame retardant layer, a hard coat layer, and a decorative layer. The electromagnetic shielding layer 3 may be provided on the main surface of the plastic housing 1, or on the side surface of the plastic housing 1 as shown in FIG. 1.

[0015] In the example of FIG. 1, an example has been described in which the entire exposed surface of the main surface of the resin housing 1 is covered with the electromagnetic wave shielding layer 3, but an electromagnetic wave shielding layer may be provided partially as in the electromagnetic wave shielding housing of the fifth embodiment described later.

[0016] 1-2. Plastic housing covering sheet The resin housing covering sheet (the present covering sheet) of the present disclosure is a sheet for forming an electromagnetic wave shielding layer of an electromagnetic wave shielding housing, as described above. The present covering sheet can physically protect the resin housing, shield electromagnetic waves, and impart a specific function. A suitable example of the present covering sheet is a conductive sheet having electromagnetic wave shielding properties. The present covering sheet may further include a non-shielding sheet having no electromagnetic wave shielding properties. Examples of non-shielding sheets include an insulating sheet having insulation properties, a heat conductive sheet that dissipates heat from the resin housing, a shielding sheet that prevents the resin housing from being seen or blocks light, a moisture-proof sheet that protects the resin housing from moisture, a decorated sheet, a flame-retardant sheet that has been given flame retardancy, a protective sheet that has been given hard coat properties, and a sheet having any combination of these functions. Suitable examples of a covering sheet having multiple functions include a covering sheet that combines electromagnetic wave shielding, insulation, and thermal conductivity, a covering sheet that combines electromagnetic wave shielding, insulation, and shielding properties, a covering sheet that combines electromagnetic wave shielding and shielding properties, and a covering sheet that combines electromagnetic wave shielding, insulation, and moisture resistance.

[0017] The coating sheet may be a single layer or a multi-layer. In the case of a multi-layer, a plurality of layers having the same function may be laminated, or layers having different functions may be laminated. For example, a coating sheet having a laminated structure of an insulating layer / conductive layer, a conductive layer / hard coat layer, a conductive layer / waterproof layer, or a thermally conductive layer / conductive layer can be exemplified.

[0018] FIG. 2 shows a schematic cross-sectional view of an example of the plastic housing covering sheet according to the first embodiment. As shown in the figure, the covering sheet 4 of the first embodiment has a laminated structure of an insulating layer 31 and a conductive layer 32. The insulating layer 31 is arranged on the plastic housing 1 side to protect the plastic housing, and the conductive layer 32 arranged on the upper layer can provide electromagnetic wave shielding properties. The conductive layer 32 and the ground (not shown) of the electronic component housed in the plastic housing 1 may be electrically connected by a pin (not shown) or the like. Alternatively, the conductive layer 32 may be arranged on the plastic housing 1 side, and the insulating layer 31 may be arranged on the upper layer. Alternatively, the insulating layers 31 may be arranged so as to sandwich the conductive layer 32 from above and below.

[0019] The present covering sheet is a precursor product of an electromagnetic shielding layer, and satisfies the following (i) to (iii). In the case of a multi-layer structure, it is not necessary for each layer to satisfy (i) to (iii), and it is sufficient for the covering sheet as a whole to satisfy (i) to (iii). (i) The plastic housing covering sheet at room temperature is placed in a temperature range of Tg to Tg+40° C. of the plastic housing covering sheet, and the breaking elongation measured at said temperature and at a tensile speed of 50 mm / min is 100 to 1500%. (ii) The plastic housing covering sheet at room temperature is placed in a temperature range of Tg to Tg+40° C. of the plastic housing covering sheet, and the breaking elongation measured at said temperature and at a tensile speed of 1000 mm / min is 50 to 1200%. (iii) The resin casing covering sheet has a puncture strength α per unit thickness at 23° C. measured in a puncture test in accordance with JIS Z1707 of 5 to 150 N / mm. In addition, Tg in the present disclosure is a value obtained by the method of this embodiment. Unless otherwise specified, Tg represents the glass transition temperature of the present covering sheet. In addition, "Tg to Tg + 40°C" is a condition for indicating the characteristics of the resin housing covering sheet, and does not limit the temperature when forming the electromagnetic wave shielding layer to this range. In addition, the numerical values ​​of (i) to (iii) above are values ​​obtained by carrying out the method and conditions described in the examples described later.

[0020] The breaking elongation refers to the permanent elongation value after the covering sheet breaks when the covering sheet is subjected to a tensile test, which was performed according to the method specified in JIS K7161:1994.

[0021] In the present covering sheet, by setting the breaking elongation of the above (i) to 100% or more and the breaking elongation of the above (ii) to 50% or more, the covering sheet can be made to have good elongation and the breakage of the electromagnetic shielding layer can be suppressed, whereas by setting the breaking elongation of the above (i) to 1500% or less and the breaking elongation of the above (ii) to 1200% or less, the occurrence of wrinkles can be suppressed. The control for satisfying the above (i) and (ii) in the present covering sheet can be adjusted by the type of the curable compound in the composition forming the present covering sheet. Specifically, it can be adjusted by the number of functional groups and equivalent weight of the curable compound. It can also be adjusted by the content of the curable compound in the composition. It can also be adjusted by the type, amount and particle size of the filler. It can also be adjusted by a flexibility adjuster that does not contribute to crosslinking, such as a plasticizer, an inert resin or an oligomer that is not reactive by itself.

[0022] The puncture strength is a value obtained in a puncture test conforming to JIS Z1707 (23°C), specifically, the strength when a stainless steel rod (diameter 1 mm) is dropped vertically onto the covering sheet and the covering sheet breaks. The puncture strength per unit thickness is obtained by dividing the puncture strength by the thickness of the covering sheet for the plastic housing. When the puncture strength per unit thickness satisfies the above (iii), it is possible to effectively prevent the covering sheet from breaking at the edge of the plastic housing, etc., and to provide a covering sheet with excellent quality.

[0023] The control to satisfy the above (iii) can be easily adjusted by the crosslink density of the electromagnetic shielding layer. A method of adjusting the type and equivalent of the functional group of the curable compound in the composition for forming the covering sheet is preferable. The curable compound preferably has any one of a hydroxyl group, a secondary amino group, or a tertiary amine group, and more preferably further has a difunctional or higher epoxy group. It can also be adjusted by the content of the curable compound in the composition. It can also be adjusted by the type, amount, and particle size of the filler. Alternatively, it can be adjusted by the type of flexibility regulator that does not contribute to crosslinking, such as a plasticizer, an inert resin that is not reactive by itself, or an oligomer.

[0024] By satisfying the above (i) and (ii), it is possible to effectively suppress the occurrence of wrinkles in the electromagnetic shielding layer that occur during the decompression process such as TOM molding. Furthermore, by satisfying the above (i) and (ii) and further satisfying (iii), it is possible to effectively prevent the sheet from breaking at the edge when heat and stress are applied to the covering sheet or when the electromagnetic shielding housing is subjected to an impact. It is also possible to suppress deviation of the lamination position. As a result, it is possible to significantly improve the quality of the covering sheet. In addition, it is possible to effectively improve appearance defects. Therefore, according to the present covering sheet, it is possible to provide an electromagnetic shielding housing having an electromagnetic shielding layer of excellent quality.

[0025] The breaking elongation of the above (i) is more preferably 150 to 1200%, and even more preferably 200 to 900%, from the viewpoint of preventing the electromagnetic shielding layer from breaking and wrinkling. By making it 100% or more, the strength of the covering sheet can be further increased, and the electromagnetic shielding layer can be more effectively prevented from breaking. Also, by making it 1500% or less, the occurrence of wrinkling can be prevented. The breaking elongation of the above (ii) is more preferably 100 to 1000%, and even more preferably 150 to 800%, from the viewpoint of preventing the electromagnetic shielding layer from breaking and wrinkling. The puncture strength α per unit thickness of the above (iii) is more preferably 10 to 100 N / mm, and even more preferably 15 to 50 N / mm, from the viewpoint of preventing the electromagnetic shielding layer from breaking.

[0026] When the covering sheet contains a thermosetting resin, the covering sheet for a plastic housing is cured by heating to become an electromagnetic wave shielding layer. The covering sheet for a plastic housing may be provided with a release sheet on one or both sides for surface protection.

[0027] The Young's modulus of this covering sheet is measured by measuring the temperature T M (However, Tg≦T M The Young's modulus measured at a tensile speed of 50 mm / min is referred to as E 50 The Young's modulus measured at a tensile speed of 1000 mm / min is expressed as E1000 In addition, the Young's modulus E measured at a certain temperature T is expressed as 50 , E 1000 E 50(T) , E 1000(T) It is sometimes expressed as:

[0028] Young's modulus E of this covering sheet 50(Tg) is preferably 15 MPa or more, more preferably 40 MPa or more. 50(Tg) is preferably 500 MPa or less, more preferably 400 MPa or less, and even more preferably 300 MPa or less. 1000(Tg) is preferably 15 MPa or more, more preferably 40 MPa or more. 1000(Tg) is preferably 300 MPa or less, more preferably 250 MPa or less, and even more preferably 200 MPa or less.

[0029] Furthermore, the E of this covering sheet 50(Tg+40℃) is preferably 5 MPa or more, more preferably 10 MPa or more. 50(Tg+40℃) is preferably 200 MPa or less, more preferably 150 MPa or less, and even more preferably 120 MPa or less. 1000(Tg+40℃) is preferably 5 MPa or more, more preferably 10 MPa or more. 50(Tg+40℃) is preferably 130 MPa or less, more preferably 100 MPa or less, and even more preferably 90 MPa or less.

[0030] Young's Modulus E 50(Tg) and E 50(Tg+40℃) By setting the Young's modulus E in the above range, it is possible to suppress breakage of the electromagnetic shielding layer and improve the conformability to the adherend. 1000(Tg) and E 1000(Tg+40℃) It is believed that by setting the thickness within the above range, the sheet does not bend during TOM molding, and wrinkles can be suppressed.

[0031] The Young's modulus can be adjusted to the above range, for example, by adjusting the crosslink density. Specifically, it can be adjusted by adjusting the number of functional groups and equivalent weight of the curable compound in the composition for forming the present covering sheet. It can also be adjusted by the content of the curable compound in the composition. It can also be adjusted by the type, amount, and particle size of the filler. It can also be adjusted by the type of flexibility regulator that does not contribute to crosslinking, such as a plasticizer, an inert resin that is not reactive by itself, or an oligomer.

[0032] Any measurement temperature T between Tg and Tg+40℃ M Young's modulus E when measured at 1000 and Young's modulus E 50 E 1000 / E 50 is preferably 0.7 or more, and more preferably 0.8 or more. 1000 / E 50 The upper limit of the ratio E is preferably 1.4 or less, more preferably 1.3 or less, and particularly preferably 1.1 or less. 1000 / E 50 By setting the thickness within the above range, breakage of the sheet at uneven portions, particularly edges, of the resin casing when processed at temperatures of Tg to Tg+40° C. can be prevented, and defects in appearance can be more effectively prevented.

[0033] From the viewpoint of preventing tearing and wrinkling of the electromagnetic shielding layer, the Tg of the present covering sheet is preferably in the range of 0 to 80° C., more preferably 0 to 40° C. When the covering sheet is a multi-layered sheet, the Tg of each layer is preferably in the above range. In the case of a multi-layered sheet, the Tg is based on the Tg of the layer with the highest Tg.

[0034] The thickness of the present covering sheet can be appropriately designed depending on the application. For applications requiring a thinner sheet, the thickness of the present covering sheet covering the upper and side surfaces of the resin housing is preferably in the range of 10 to 1000 μm, more preferably 15 to 500 μm, and even more preferably 20 to 250 μm.

[0035] When this covering sheet is used as an insulating layer, the surface resistance is 1.0×107 It is preferable that the resistance is Ω / □ or more, and 1.0×10 8 More preferably, it is 1.0×10 9 It is more preferable that the surface resistance of the conductive layer is 1.0×10 2 It is preferable that the resistance is Ω / □ or less, and 1.0×10 1 It is more preferable that the resistance is Ω / □ or less, and further preferably that the resistance is 1.0Ω / □ or less.

[0036] The covering sheet includes a binder component. The binder component is a component that serves as the base of the electromagnetic shielding layer. Examples of resins used in the binder component include thermosetting resins, photocurable resins, and mixtures thereof. Curable compounds that crosslink with these resins are also included in the binder component. As the thermosetting resin, in addition to self-crosslinking thermosetting resins, thermosetting resins that can react with curable compounds are suitable. These may be combined. As the binder resin, a combination of a thermosetting resin and a curable compound is suitable. When a curable compound is used, a thermosetting resin having a reactive functional group that can react with the curable compound is preferred. The binder resin can be used alone or in combination of two or more types.

[0037] The thermosetting resin has a curable compound or a reactive functional group that self-crosslinks, such as a phenolic hydroxyl group, an acid anhydride group, a methoxymethyl group, a carboxyl group, an amino group, an epoxy group, an oxetanyl group, an oxazoline group, an oxazine group, an aziridine group, a thiol group, an isocyanate group, a blocked isocyanate group, a blocked carboxyl group, a silanol group, etc.

[0038] Examples of the thermosetting resin include polyurethane resin, polyurethane urea resin, phenoxy resin, acrylic resin, polyester resin, polyamide resin, epoxy resin, polystyrene resin, polycarbonate resin, polyamideimide resin, polyesteramide resin, polyetherester resin, alkyd resin, polyimide resin, benzoxazine resin, amino resin, polylactic acid resin, oxazoline resin, silicone resin and fluororesin. From the viewpoint of increasing high temperature resistance, epoxy resin, polyurethane resin, polyurethane urea resin, polycarbonate resin, phenoxy resin, polyimide resin, polyamideimide resin and polyamide resin are preferred. In particular, polyurethane resin, polyurethane urea resin and polycarbonate resin are more preferred because they have excellent dispersibility of the filler described below and can increase puncture strength.

[0039] From the viewpoint of improving adhesion to a resin housing, the acid value of the thermosetting resin is preferably 1 to 30 mgKOH / g, more preferably 1 to 20 mgKOH / g, and further preferably 1 to 12 mgKOH / g.

[0040] The average molecular weight of the thermosetting resin is preferably 30,000 or more from the viewpoint of improving the breaking elongation, and more preferably 50,000 or more. The upper limit of the average molecular weight is not particularly limited, but is preferably 1,000,000 or less from the viewpoint of improving the wet heat resistance, and more preferably 500,000 or less.

[0041] The curable compound has a functional group capable of reacting with the thermosetting resin. It is preferable that the functional group is a plurality of functional groups. Examples of the curable compound include epoxy compounds, isocyanate compounds, polycarbodiimide compounds, aziridine compounds, acid anhydride group-containing compounds, dicyandiamide compounds, amine compounds such as aromatic diamine compounds, phenolic compounds such as phenol novolac resins, and organometallic compounds. The curable compound may be a resin or a low molecular weight compound. When a resin is used as the curable compound, the thermosetting resin and the curable compound are distinguished by the fact that the one with a higher content is the thermosetting resin and the one with a lower content is the curable compound. The curable compound may be used alone or in combination of two or more kinds.

[0042] From the viewpoint of effectively suppressing wrinkles and breakage of the electromagnetic shielding layer and improving adhesion to the resin housing, it is preferable to use a curable compound (c) having either a hydroxyl group, a secondary amino group, or a tertiary amine group and having a bifunctional or higher epoxy group (hereinafter also referred to as curable compound (c)). By using the curable compound (c), the curing reaction before the curing process can be promoted to some extent, and breakage during elongation of the covering sheet in TOM molding or the like can be effectively prevented.

[0043] Suitable examples of the curable compound (c) include Mitsubishi Chemical's jER630 and 1001. In addition, among the bifunctional epoxy compounds exemplified below, compounds having any one of a hydroxyl group, a secondary amino group, or a tertiary amine group are also suitable for use as the curable compound.

[0044] In addition to the curable compound (c), a curable compound (d) having a di- or higher functional epoxy group may be further added. Examples of compounds having a bifunctional epoxy group include bisphenol-based diglycidyl ethers such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol E diglycidyl ether, bisphenol Z diglycidyl ether, bisphenol S diglycidyl ether, bisphenol AD ​​diglycidyl ether, bisphenol acetophenone diglycidyl ether, bisphenol trimethylcyclohexane diglycidyl ether, bisphenol fluorene diglycidyl ether, tetramethyl bisphenol A diglycidyl ether, tetramethyl bisphenol F diglycidyl ether, tetra-t-butyl bisphenol A diglycidyl ether, and tetramethyl bisphenol S diglycidyl ether; biphenol-based diglycidyl ethers such as biphenol diglycidyl ether, tetramethyl biphenol diglycidyl ether, dimethyl biphenol diglycidyl ether, and tetra-t-butyl biphenol diglycidyl ether; hydroquinone diglycidyl ether; benzenediol diglycidyl ethers, such as dihydroanthracene diglycidyl ether, methylhydroquinone diglycidyl ether, dibutylhydroquinone diglycidyl ether, resorcinol diglycidyl ether, and methylresorcinol diglycidyl ether; aromatic diglycidyl ethers, such as dihydroanthrahydroquinone diglycidyl ether, dihydroxydiphenyl ether diglycidyl ether, thiodiphenol diglycidyl ether, and dihydroxynaphthalene diglycidyl ether; Epoxy compounds in which hydrogen has been added to the aromatic ring of a diglycidyl ether selected from the bisphenol diglycidyl ethers, biphenol diglycidyl ethers, benzenediol diglycidyl ethers, and aromatic diglycidyl ethers; epoxy resins produced from various carboxylic acids, such as adipic acid, succinic acid, phthalic acid, tetrahydrophthalic acid, methylhexahydrophthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, biphenyldicarboxylic acid, and dimer acid, and epihalohydrin;Examples of the alkylene glycol diglycidyl ether include (poly)alkylene glycol diglycidyl ethers consisting only of a chain structure, such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, 1,5-pentanediol diglycidyl ether, polypentamethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polyhexamethylene glycol diglycidyl ether, 1,7-heptanediol diglycidyl ether, polyheptamethylene glycol diglycidyl ether, 1,8-octanediol diglycidyl ether, 1,10-decanediol diglycidyl ether, and 2,2-dimethyl-1,3-propanediol diglycidyl ether; and alkylene glycol diglycidyl ethers having a cyclic structure, such as 1,4-cyclohexanedimethanol diglycidyl ether. Examples of commercially available products include EPICLON 830, 840, 850, 860, 1050, 2050, 3050, 4050, 7050, HM-091, and 101 manufactured by DIC, and Denacol EX-211, 212, 252, 711, and 721 manufactured by Nagase ChemteX.

[0045] From the viewpoint of adjusting the curing speed of the semi-curing (B-stage curing) and the main curing (C-stage curing), it is preferable to use a curable compound (e) that does not contain an epoxy group in addition to the curable compound (c). Suitable examples of the curable compound (e) include a combination of one or more of an aziridine compound, a polycarbodiimide compound, an isocyanate compound, an imidazole compound, and a maleimide group-containing compound.

[0046] In a heat press or the like, the epoxy group of the epoxy compound thermally crosslinks with the carboxyl group or hydroxyl group of the thermosetting resin to obtain a crosslinked structure. As the epoxy compound, an epoxy compound that is liquid at room temperature (25°C) is also suitable. Specific examples include liquid bisphenol-type epoxy resins such as "R140P" (epoxy equivalent 188) manufactured by Mitsui Chemicals, Inc., "DER383" manufactured by Dow Chemical Company, and "Epicoat #807" (epoxy equivalent 170) manufactured by Japan Epoxy Resins.

[0047] The content of the curable compound (c) is preferably 0.1 to 100 parts by mass, more preferably 1 to 50 parts by mass, and even more preferably 5 to 30 parts by mass, relative to 100 parts by mass of the thermosetting resin. By setting the content within the above range, a strong crosslinked structure is formed in the electromagnetic shielding layer, and excessive curing of the electromagnetic shielding layer is suppressed, thereby improving the conformability to uneven shapes. Furthermore, an electromagnetic shielding layer that can effectively suppress wrinkles and breakage in a TOM molding method or the like can be formed.

[0048] The ratio of the curable compound (d) / curable compound (c) is preferably 0 to 50, more preferably 0.1 to 25. By setting the ratio within the above range, a strong crosslinked structure is formed in the coating layer, and excessive curing of the coating layer is suppressed, thereby improving the conformability to the uneven shape. Furthermore, a coating layer that can effectively suppress wrinkles and breakage in a TOM molding method or the like can be formed.

[0049] The covering sheet may further contain a filler. When insulation is required, an insulating filler is used, when conductivity is required, a conductive filler is used, and when electromagnetic wave absorption is further required, an electromagnetic wave absorbing filler is used. The shape of the filler can be appropriately selected. For example, flake-shaped (scale-shaped), needle-shaped, spherical, dendritic, and fibrous fillers can be mentioned. In particular, it is preferable to use a flake-shaped filler from the viewpoint of excellent electromagnetic wave shielding properties. Also, fillers of different shapes may be used in combination. Suitable examples include a combination of a flake-shaped filler and a spherical filler, and a flake-shaped filler and a dendritic filler.

[0050] Average particle size D of flake-shaped conductive filler 50 The average particle diameter D of the dendritic conductive filler is preferably 1 to 100 μm, more preferably 2 to 80 μm, further preferably 3 to 50 μm, and particularly preferably 5 to 20 μm. 50 Similarly, the preferred range of is preferably 0.5 to 100 μm, more preferably 1.0 to 80 μm, further preferably 1.5 to 50 μm, and particularly preferably 2 to 20 μm.

[0051] From the viewpoint of preventing the electromagnetic shielding layer from breaking and wrinkling, the filler content is preferably 30 to 80 mass % and more preferably 40 to 70 mass % relative to 100 mass % of the covering sheet. In the case of a multi-layered covering sheet, the total of all layers (n-layer filler content×n-layer thickness / (total thickness of the electromagnetic shielding layer)) (where n is an integer of 2 or more) is preferably 30 to 80 mass %, more preferably 40 to 70 mass %.

[0052] Examples of the insulating filler include non-metallic inorganic fillers such as silica, alumina, boron nitride, aluminum nitride, magnesium silicon nitride, silicon carbide, titania, glass, ceramics, etc. The insulating filler may be used alone or in combination of two or more kinds.

[0053] Examples of the conductive filler include metal fillers, conductive ceramic fillers, and mixtures thereof. Examples of the metal filler include metal powders such as gold, silver, copper, and nickel, alloy powders such as solder, and core-shell fillers such as silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder. From the viewpoint of obtaining excellent conductive properties, conductive fillers containing silver are preferred. From the viewpoint of cost, silver-coated copper powder is particularly preferred.

[0054] Examples of the electromagnetic wave absorbing filler include iron alloys such as iron, Fe-Ni alloy, Fe-Co alloy, Fe-Cr alloy, Fe-Si alloy, Fe-Al alloy, Fe-Cr-Si alloy, Fe-Cr-Al alloy, and Fe-Si-Al alloy, ferrite-based substances such as Mg-Zn ferrite, Mn-Zn ferrite, Mn-Mg ferrite, Cu-Zn ferrite, Mg-Mn-Sr ferrite, and Ni-Zn ferrite, and carbon fillers. Examples of the carbon filler include acetylene black, ketjen black, furnace black, carbon black, carbon fiber, fillers made of carbon nanotubes, graphene fillers, graphite fillers, and carbon nanowalls.

[0055] The covering sheet may contain a flexibility regulator. The flexibility regulator can reduce wrinkling and tearing of the covering sheet during molding. Examples of the flexibility regulator include a plasticizer and an inert thermoplastic resin.

[0056] Examples of the plasticizer include fatty acid esters, phthalic acid esters, aromatic polyvalent carboxylic acid esters, and polyesters. Examples of fatty acid esters include trioctyl trimellitate (TOTM), manufactured by Mitsubishi Gas Chemical Trading Co., Ltd., butyl stearate, Unistar M-9676, Unistar M-2222SL, Unistar H-476, Unistar H-476D, Panasate 800B, Panasate 875, Panasate 810 (all manufactured by NOF Corp.), DBA, DIBA, DBS, DOA, DINA, DIDA, DOS, BXA, DOZ, and DESU (all manufactured by Daihachi Chemical Co., Ltd.). Examples of phthalic acid esters include DMP, DEP, DBP, #10, BBP, DOP, DINP, and DIDP (hereinafter, manufactured by Daihachi Chemical Co., Ltd.), PL-200, and DOIP (all manufactured by C.G. Ester Co., Ltd.), and Sanso Cizer DUP (manufactured by New Japan Chemical Co., Ltd.). Examples of aromatic polycarboxylic acid esters include TOTM (manufactured by Daihachi Chemical Industry Co., Ltd.), Monocizer W-705 (manufactured by Daihachi Chemical Industry Co., Ltd.), UL-80, and UL-100 (manufactured by ADEKA Corporation). Examples of polyesters include Polysizer TD-1720, Polysizer S-2002, Polysizer S-2010 (all manufactured by DIC Corporation), and BAA-15 (manufactured by Daihachi Chemical Industry Co., Ltd.). Among these, DMP, DEP, DBP, DOP, DINP, DIDP, and TOTM are more preferable. The plasticizers may be used alone or in combination of two or more.

[0057] Examples of the inert thermoplastic resin include polyolefin resins, vinyl resins, styrene-acrylic resins, diene resins, terpene resins, petroleum resins, cellulose resins, polyamide resins, polyurethane resins, polyester resins, polycarbonate resins, polyimide resins, liquid crystal polymers, and fluororesins. Although not particularly limited, polyamide resins, polyurethane resins, polyester resins, polycarbonate resins, polyimide resins, liquid crystal polymers, and fluororesins are more preferable from the viewpoint of heat resistance.

[0058] Furthermore, the coating sheet may contain a tackifier resin to improve adhesion to the substrate. The tackifier resin is a component that supplementarily improves adhesive strength, has a weight-average molecular weight of less than 5,000, and is distinguished from the thermoplastic resin and binder resin. Examples of the tackifier resin include rosin resin, terpene resin, alicyclic petroleum resin, and aromatic petroleum resin.

[0059] The covering sheet may further contain a colorant, a flame retardant, a lubricant, an antiblocking agent, etc. Examples of the flame retardant include a halogen-containing flame retardant, a phosphorus-containing flame retardant, a nitrogen-containing flame retardant, an inorganic flame retardant, etc. Examples of the lubricant include a fatty acid ester, a hydrocarbon resin, paraffin, a higher fatty acid, a fatty acid amide, an aliphatic alcohol, a metal soap, a modified silicone, etc. Examples of the antiblocking agent include calcium carbonate, silica, polymethylsilsesquioxane, and aluminum silicate.

[0060] In the example of FIG. 2, an example of a covering sheet consisting of a multi-layer structure of an insulating layer 31 / a conductive layer 32 is given, but as described above, the covering sheet may be a single-layer covering sheet or a covering sheet consisting of a multi-layer structure having the same function. In addition, a second layer may be patterned at an arbitrary position of the first layer. For example, by using a covering sheet in which an insulating layer 31 is patterned at an arbitrary position of the conductive layer 32, the conductive layer 32 can be formed on the entire exposed surface of one main surface of the resin housing 1, and an electromagnetic wave shielding layer having the insulating layer 31 can be formed at a location requiring insulation protection. According to this covering sheet, it is possible to effectively prevent the covering position from being displaced, and therefore the design freedom of the covering sheet can be significantly increased.

[0061] 1-3. Manufacturing method of plastic housing covering sheet The method for producing the present covering sheet is not particularly limited, but examples thereof include a method of applying a composition in which the material such as the binder resin forming the electromagnetic wave shielding layer is dissolved in a solvent or the like to a release sheet. Examples of the application method include a gravure coating method, a kiss coating method, a die coating method, a lip coating method, a comma coating method, a blade method, a roll coating method, a knife coating method, a spray coating method, a bar coating method, a spin coating method, a dip coating method, or various printing methods. In the case of a multi-layer structure, known methods such as a lamination method and a method of laminating via an easy adhesive can be applied.

[0062] 1-4. Applications of plastic housing covering sheets The present covering sheet is particularly suitable for use in covering resin housings, but may also be used to cover other objects to be covered. Electromagnetic wave shielding housings using the present covering sheet are preferably provided in vehicles, liquid crystal displays, touch panels, and other electronic devices, such as notebook PCs, mobile phones, smartphones, and tablet terminals.

[0063] 1-5. Manufacturing method for electromagnetic shielding enclosure An example of a method for manufacturing an electromagnetic shielding case using the present covering sheet, TOM molding, will be described. However, the method for manufacturing the present electromagnetic shielding case is not limited to the following. The present covering sheet may be used to form an electromagnetic shielding layer by a method other than TOM molding (e.g., vacuum molding, pressure molding, vacuum pressure molding, press molding, injection molding). For example, the electromagnetic shielding layer can be formed from the present covering sheet by the method described in Japanese Patent No. 7193031.

[0064] The method for producing the electromagnetic wave shielding housing of the present disclosure includes steps of preparing a resin housing (step A), preparing a resin housing covering sheet cut to a predetermined size (step B), and forming an electromagnetic wave shielding layer using the present covering sheet or the present laminated sheet in which the present covering sheet is laminated (step C), thereby obtaining an electromagnetic wave shielding housing covered and protected by the electromagnetic wave shielding layer formed from the resin housing covering sheet of the present disclosure. Step C will be described below with reference to the schematic manufacturing process diagrams of Figs. 3 to 5.

[0065] First, the resin housing 1 is placed on the stage 5 of the lower space 21 in the box 20 having the lower space 21 and the upper space 22. Next, the covering sheet 4 is placed on the partition plate 6 so as to separate the upper space 22 from the lower space 21 (see FIG. 3). Then, the inside of the box 20 is made into a vacuum state, and the covering sheet 4 is heated by the heat source 7 to around the Tg of the covering sheet 4 to soften it. Around the Tg is, for example, in the range of Tg ± 20°C. Note that, when the covering sheet 4 is a multi-layered sheet, the Tg of the layer with the highest Tg is used as the reference. Note that as long as the covering sheet 4 can be fixed, a fixing jig for sandwiching the sheet may be used instead of the partition plate.

[0066] As the temperature of the covering sheet 4 approaches the temperature around the Tg due to heating by the heating source 7, the covering sheet 4 loses flatness and undulation appears (see FIG. 4). When heating is continued, the undulation of the covering sheet 4 is reduced and the covering sheet 4 begins to bend around the center due to its own weight (see FIG. 5). By heating the covering sheet 4 to this state, it is possible to effectively prevent wrinkles from occurring in the electromagnetic shielding layer and improve the quality. In addition, in order to improve the adhesion of the electromagnetic shielding layer to the plastic housing 1, it is preferable to heat the stage 5 on which the plastic housing 1 is placed. Heating has the effect of improving production efficiency during continuous production. The temperature of the stage 5 during heating is, for example, 50 to 120° C. It is preferable that the temperature of the stage 5 during heating is within the range of Tg±20° C. from the viewpoint of improving continuous productivity.

[0067] If necessary, the stage 5 installed in the lower space 21 is moved upward to bring a part of the covering sheet 4 into contact with or close to the upper surface of the plastic housing 1. The surface of the covering sheet 4 is then pressurized from the upper space 22 by air or compressed air. The covering sheet 4 then conforms to the uneven surface of the plastic housing 1. Next, the excess covering sheet is removed. If a thermosetting resin is used as the binder resin, a heat curing process is performed, and if a photocuring resin is used, a photocuring process is performed. Through these steps, an electromagnetic wave shielding housing 10 having an electromagnetic wave shielding layer 3 as shown in FIG. 1 is obtained.

[0068] According to the above method, the covering sheet can be cut to fit the covering area, and a versatile electromagnetic shielding layer can be formed regardless of the shape, arrangement, etc. of the plastic casing. In addition, since the covering sheet is applied to the entire surface to form the electromagnetic shielding layer, and then the excess electromagnetic shielding layer is cut off, there is an advantage in that precise alignment between the covering sheet and the plastic casing is not required.

[0069] By satisfying the above (i) to (iii), the present covering sheet can form a high-quality electromagnetic shielding layer even for a resin housing that is made light, thin, short, and small. By using the TOM molding method, the present covering sheet can be heated and softened by applying pressure difference to conform to a three-dimensional uneven shape, thereby significantly improving productivity.

[0070] 2. Second embodiment A plastic housing covering sheet according to a second embodiment will be described. The plastic housing covering sheet according to the second embodiment differs from the first embodiment in the layer structure as described later, but the basic structure and manufacturing method are the same as those of the first embodiment. In the following figures, the same elements and members as those described above are appropriately designated by the same reference numerals.

[0071] 6 shows a schematic cross-sectional view of an example of the resin housing covering sheet according to the second embodiment. The covering sheet 4a is formed by laminating a first layer 41, a second layer 42, and a third layer 43, all of which are insulating layers, in this order. The first layer 41, the second layer 42, and the third layer 43 may each independently have the same function or different functions. The preferred components, amounts, and properties of the first, second, and third layers are the same as those of the first embodiment.

[0072] The first layer 41, which is disposed so as to face the resin housing, is preferably designed to reduce warping and improve embedding properties. The second layer 42 is preferably designed to improve conformability to the three-dimensional shape of the resin housing in TOM molding and to reduce warping. For this reason, it is preferable that the curable compound of the first layer and the second layer contains a liquid epoxy compound.

[0073] A liquid epoxy compound refers to an epoxy compound that is liquid at 25° C. Suitable examples include jER (registered trademark (omitted below)) YL980, jERYL983U, jER152, jER630, jERYX8000 (all trade names, manufactured by Mitsubishi Chemical Corporation), EPICLON (registered trademark), and HP-4032 (all trade names, manufactured by DIC Corporation). The liquid epoxy compounds may be used alone or in combination of two or more kinds.

[0074] The third layer 43 is preferably designed to optimize hardness and enhance durability of the covering sheet, in addition to adjusting the film thickness. It is preferable that the third layer 43 contains a filler to enhance durability.

[0075] According to the second embodiment, the three-layer structure increases the design freedom of each layer, and the electromagnetic shielding layer has high functionality. As a result, the adhesion and conformability of the joint surface between the cover sheet 4a and the plastic housing 1 are improved, and wrinkles in the electromagnetic shielding layer and breakage at the edges of the electromagnetic shielding layer can be effectively prevented.

[0076] In the second embodiment, an example of a covering sheet having a three-layer structure is given, but the covering sheet may be a single layer or multiple layers (two layers, four or more layers) without departing from the spirit of the present disclosure.

[0077] 3. Third embodiment The manufacturing method of the electromagnetic wave shielding housing according to the third embodiment differs from that of the first embodiment in that a laminate sheet having the present covering sheet is used, etc., but the basic structure of the electromagnetic wave shielding housing and the basic manufacturing method are the same as those of the first embodiment.

[0078] 7 is a schematic diagram showing an example of a manufacturing process of the electromagnetic shielding housing according to the third embodiment. In the first embodiment, the covering sheet 4 is placed on the partition plate 6, but in the third embodiment, a laminated sheet 50 is placed on the partition plate 6. The laminated sheet 50 has a support layer 8 and a covering sheet 4 formed on the support layer 8. The size of the covering sheet 4 is set to a size required for forming an electromagnetic shielding layer. This method makes it possible to omit the step of cutting off unnecessary parts after forming the electromagnetic shielding layer.

[0079] The method for manufacturing the laminated sheet 50 is not limited, but a method of attaching the covering sheet 4 to a desired position on the support layer 8 is simple. A suitable method is, for example, a method of heating the covering sheet 4 to the support layer 8 and temporarily attaching it. The support layer 8 has a role of fixing (in this example, placing and fixing on the partition plate 6) during the manufacturing process and a role of supporting the covering sheet. The support layer can also be called a peeling layer because it is peeled off after the electromagnetic wave shielding layer is formed. The laminated sheet 50 is coated on the resin housing 1 by the same method as in the first embodiment to form the electromagnetic wave shielding layer 3, and then the support layer 8 is peeled off to obtain the electromagnetic wave shielding housing.

[0080] The support layer 8 is not particularly limited as long as it has the above-mentioned functions. Suitable examples include polyvinyl chloride (PVC), polyolefin, and the like. The thickness of the support layer 8 is preferably 5 to 500 μm, and more preferably 10 to 250 μm, from the viewpoint of improving the conformability to the adherend. The Tg of the support layer 8 is preferably 30 to 90° C., and more preferably 40 to 80° C., from the viewpoint of improving the conformability to the adherend. The Tg1 of the cover sheet 4 and the Tg2 of the support layer 8 are |Tg2-Tg1|≦100℃ By setting the value in this range, the ability to conform to the uneven shape of the resin housing can be more effectively improved. |Tg2-Tg1|≦80℃ The Tg2 of the support layer can be adjusted by the type of resin and the manufacturing conditions thereof. The temperature inside the box 20 is preferably set within a range of ±20° C. between the higher of Tg1 and Tg2.

[0081] The alignment between the resin housing and the cover sheet can be performed by any known method without any restrictions. For example, precise alignment can be performed by aligning a mark on the support layer with a mark on the stage.

[0082] According to the covering sheet of the third embodiment, there is no need to use a covering sheet 4 of a size that can be placed on the partition plate 6 of the box 20, so that loss of the covering sheet 4 can be eliminated and costs can be reduced. In addition, the covering sheet 4a can be adjusted to a desired size according to the size of the resin housing, so that versatility can be significantly improved. In addition, since the covering sheet 4 can be supported by the support layer 8, there is an advantage in that it is easy to realize a thin electromagnetic wave shielding layer.

[0083] 4. Fourth embodiment The laminated sheet according to the fourth embodiment is different from the laminated sheet according to the third embodiment, which does not have the release layer 9, in that the laminated sheet according to the fourth embodiment has a release layer 9 between the support layer 8 and the cover sheet 4a. FIG. 8 shows a schematic plan view of an example of the laminated sheet according to the fourth embodiment, and FIG. 9 shows a cross-sectional view of the IX-IX cut portion of FIG. 8. As shown in these figures, the support layer 8, the release layer 9, and the cover sheet 4a are laminated in this order. The areas of the layers are support layer 8>release layer 9>cover sheet 4a, and in the top view, the frame area of ​​the release layer 9 is on the outside of the cover sheet 4a, and the frame area of ​​the support layer 8 is on the outside of the release layer 9. The support layer 8 has a size that can be placed on the partition plate 6, and the cover sheet 4a has an optimal size for forming an electromagnetic wave shielding layer. The release layer 9 has an area extended from the end of the cover sheet 4a in consideration of ease of peeling after the electromagnetic wave shielding layer is formed. Suitable examples of the release layer 9 include polypropylene (PP) and polyethylene (PE).

[0084] The thickness of the release layer 9 is, for example, about 5 to 1000 μm. From the viewpoint of improving the conformability to the adherend, the thickness is preferably 5 to 500 μm, and more preferably 10 to 250 μm. The Tg of the release layer 9 is preferably -50 to 50°C, and more preferably -20 to 20°C.

[0085] According to the fourth embodiment, by using the release layer 9, it is possible to effectively prevent adhesion between the support layer 8 and the cover sheet 4a, prevent damage to the electromagnetic shielding layer 3, and increase the manufacturing yield. It is also possible to significantly increase the options for materials for the support layer 8. Also, it is possible to effectively improve the misalignment of the stacking positions.

[0086] 5. Fifth embodiment The fifth embodiment differs from the first embodiment in that an electromagnetic shielding layer is provided on a part of one main surface of the electromagnetic shielding housing, in that an electromagnetic shielding layer is provided on the entirety of one main surface of the electromagnetic shielding housing. 10 shows a schematic cross-sectional view of an example of an electromagnetic wave shielding housing according to the fifth embodiment. An electromagnetic wave shielding layer 3a provided on an electromagnetic wave shielding housing 11 covers a part of an exposed surface of one main surface of a resin housing 1. The partially covered electromagnetic wave shielding layer 3a can be formed, for example, by using the laminate sheet of the third or fourth embodiment.

[0087] According to the electromagnetic shielding housing of the fifth embodiment, an electromagnetic shielding layer can be easily formed at a position that requires protection. Moreover, by using the laminated sheet of the third or fourth embodiment, misalignment can be effectively prevented. Moreover, as shown in FIG. 11, a plurality of covering sheets 4 may be laminated on a support layer 8. According to this method, a plurality of electromagnetic shielding layers 3 having the necessary functions can be formed at a time at desired positions according to the functions required for the electromagnetic shielding housing. EXAMPLES

[0088] The present disclosure will be described in detail below with reference to examples and comparative examples, but the present disclosure is not limited to the following examples. Note that the "parts" and "%" below are values ​​based on "parts by mass" and "% by mass", respectively.

[0089] A. Covering sheet The raw materials used in the examples are shown below. A-1.Thermosetting resin [Synthesis of thermosetting resin r1] A glass flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen inlet tube, and a pressure reducing device was charged with 166 parts of terephthalic acid, 146 parts of adipic acid, 212 parts of 3-methyl-1,5-pentanediol, and 25 parts of ethylene glycol, and stirred while passing nitrogen gas through it. The temperature was gradually increased under normal pressure, and the mixture was reacted at 200 to 230°C for about 8 hours to obtain a liquid with an acid value of 43 mgKOH / g. Then, 0.01 parts of tetra-n-butoxytitanium was charged, and after nitrogen replacement, the mixture was stirred at 180°C for 30 minutes under a sealed condition. Then, the mixture was reacted at 230°C and 5 mmHg for 2 hours to obtain a polyester diol with an acid value of 1.1 mgKOH / g, a hydroxyl value of 114.2 mgKOH / g, and a molecular weight of 982. The acid value and hydroxyl value were determined by weighing the thermosetting resin, measuring the same using an automatic titrator GT-200 manufactured by Mitsubishi Chemical Analic Corporation in accordance with the potentiometric titration method of JIS K0070, and converting the measured values ​​into solid content values.

[0090] Next, 734 parts of the polyester diol, 23.9 parts of dimethylolpropionic acid, 219 parts of toluene diisocyanate, and 242 parts of toluene were charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, and reacted for 8 hours at 50° C. under a nitrogen atmosphere. 1200 parts of toluene were added to this to obtain a urethane prepolymer solution having an isocyanate group at its end.

[0091] Next, the obtained urethane prepolymer solution was heated to 70°C, and while maintaining the temperature, a solution containing 20.0 parts of 1,3-diaminopropane, 3.1 parts of benzylamine, 600 parts of 2-propanol, and 961 parts of toluene was added dropwise over 1 hour. After the addition was completed, the mixture was allowed to react at 70°C for an additional 6 hours to obtain a polyurethane resin with a molecular weight (Mw) of 130,000, an acid value of 10 mgKOH / g, a Tg of 20°C, and a solid content of 25%.

[0092] [Synthesis of thermosetting resin r2] In the same manner as in the synthesis of thermosetting resin r1, a polyurethane resin having a molecular weight (Mw) of 250,000, an acid value of 11 mgKOH / g, a Tg of 20° C., and a solid content of 18% was obtained.

[0093] [Synthesis of thermosetting resin r3] In the same manner as in the synthesis of the thermosetting resin r1, a polyurethane resin having a molecular weight (Mw) of 80,000, an acid value of 10 mgKOH / g, a Tg of 20° C., and a solid content of 40% was obtained.

[0094] [Synthesis of thermosetting resin r4] In the same manner as in the synthesis of thermosetting resin r1, a polyurethane resin having a molecular weight (Mw) of 20,000, an acid value of 12 mgKOH / g, a Tg of 20° C., and a solid content of 55% was obtained.

[0095] A-2. Curing compound As the curable compound (c), the following curable compounds (c1) and (c2) were used. Curable compound (c1): Trifunctional epoxy resin "jER630", containing tertiary amine, manufactured by Mitsubishi Chemical Corporation Curable compound (c2): Bifunctional epoxy resin "jER1001", containing hydroxyl groups, manufactured by Mitsubishi Chemical Corporation As the curable compounds (d) and (e), the following compounds were used. Curable compound (d): Multifunctional epoxy resin "jER175S70", manufactured by Mitsubishi Chemical Corporation Curable compound (e): Aziridine compound "ChemiTite PZ-33", manufactured by Nippon Shokubai Co., Ltd.

[0096] A-3. Filler Filler f1: flake silver filler (D 50 =4.0~7.0μm) Fukuda Metal Industry Co., Ltd. Filler f2: Dendritic silver-coated copper filler (scale silver filler D 50 = 10.4μm) Made by DOWA

[0097] B. Support layer Support layer X1: polyvinyl chloride sheet made by melt rolling polyvinyl chloride powder (manufactured by Zeon Corporation), Tg: 76°C Support layer X2: polyvinyl chloride sheet made by the solvent method using polyvinyl chloride powder (manufactured by Zeon Corporation), Tg: 54°C Support layer X3: Cycloolefin polymer ZEONOR (manufactured by Zeon Corporation) is melt extrusion-produced olefin sheet, Tg: 125°C

[0098] C.Release layer Release layer Y1: Co-extrusion protective film, Eltec MX 157N3U, manufactured by Nihon Matai Co., Ltd., Tg: -1°C

[0099] D.Measurement method D-1. Glass transition temperature Tg The Tg of the measurement sample (resin housing covering sheet), release layer and support layer of each example and comparative example was measured using a dynamic viscoelasticity measuring device DVA-200 (manufactured by IT Measurement and Control Co., Ltd.) in accordance with JIS K7198. The measurement was performed by cutting the resin housing covering sheet of each example to 0.5 cm x 3 cm and removing the release film. The deformation mode was tensile, and the temperature at which the main dispersion peak of the loss tangent (tan δ) appeared was measured at a strain of 0.08%, a frequency of 10 Hz, and a heating rate of 10 ° C. / min.

[0100] D-2. Breaking elongation and Young's modulus The resin housing covering sheet with release film of each Example and Comparative Example obtained by the method described below was cut into a size of 20 mm wide x 60 mm long. Next, the release film was peeled off to obtain a measurement sample (resin housing covering sheet) made of the covering sheet. Each measurement sample (covering sheet) was placed from room temperature to a temperature of Tg+40°C (in air, 50% RH), and one minute later, a tensile test was performed at that temperature, a tensile speed of 50 mm / min, and a relative humidity of 50% using a small tabletop testing machine EZ-TEST (manufactured by Shimadzu Corporation) with an effective tensile size of 20 x 23 mm, and the elongation at break at a tensile speed of 50 mm / min was obtained. In addition, the tangent of the linear region before the yield point was obtained in the stress-strain curve during the tensile test, and the Young's modulus E 50(Tg+40℃) Similarly, each measurement sample (covering sheet) was placed from room temperature to a temperature of Tg (in air, 50% RH), and the breaking elongation and Young's modulus E 50(Tg) was measured. Similarly, the covering sheet was placed in an atmosphere at room temperature to Tg+40°C, and one minute later, a tensile test was carried out at that temperature, under conditions of a tensile speed of 1000 mm / min and a relative humidity of 50%, with an effective tensile size of 20 x 23 mm, to determine the elongation at break at a tensile speed of 1000 mm / min. Furthermore, using the same method with the above device, the Young's modulus E 1000(Tg+40℃) Similarly, each measurement sample (covering sheet) was placed from room temperature to a temperature of Tg (in air, 50% RH), and the breaking elongation and Young's modulus E at a tensile speed of 1000 mm / min were measured in the same manner. 1000(Tg) was measured.

[0101] D-3.Piercing strength The resin housing covering sheet (100 mm x 100 mm) of each example and comparative example was prepared, and the puncture strength per unit film thickness at 23 ° C. was measured by a puncture test conforming to JIS Z1707. Specifically, the sample was clamped in a sample installation jig having an opening of 80 mm in diameter, and installed in a TE-1003 low-temperature and high-temperature tank peel tester II type (manufactured by Tester Sangyo Co., Ltd.) equipped with a stainless steel rod (length 17 mm) having a diameter of 1 mm as a measurement probe. Under the condition of a measurement temperature of 23 ° C., the probe was penetrated into the resin housing covering sheet at a speed of 100 mm / min, and the strength at the time of breakage was recorded and used as the puncture strength. The puncture strength value obtained was divided by the thickness of the resin housing covering sheet to calculate the puncture strength α per unit film thickness.

[0102] D-4. Film thickness The thickness of the electromagnetic shielding layer in the electromagnetic shielding housing was measured by polishing the cross section and measuring the thickness of the thickest part in the upper surface area of ​​the electromagnetic shielding housing with a laser microscope. Five samples of the cross sections of different electromagnetic shielding housings were similarly measured, and the average value was taken as the thickness.

[0103] E. Preparation of resin housing covering sheet and laminated sheet [Example 1] 100 parts of thermosetting resin r1 (solid content), 8 parts of jER630, 2 parts of jER175S70, 0.5 parts of PZ-33, 154 parts of filler f1, and 31 parts of filler f2 were charged into a container, toluene was added so that the non-volatile content concentration was 33% by mass, and the mixture was stirred with a disperser for 10 minutes to obtain a composition. This composition was applied to a release film (a polyethylene terephthalate film treated with a release agent, thickness 50 μm) using a doctor blade so that the dry thickness was 30 μm. Next, the resin housing covering sheet with a release film of Example 1 was obtained by drying at 100 ° C. for 2 minutes. The obtained resin housing covering sheet with release film was cut into 100 mm squares, the release film was peeled off, and a support layer X1 (300 mm square) having a release function was laminated on the surface where the release film had been laminated, thereby obtaining a laminated sheet (support layer X1 / electromagnetic shield layer) according to Example 1. The resin housing covering sheet was placed in the center of the support layer X1 in a plan view.

[0104] [Examples 2 to 18, Comparative Examples 1 to 4] Laminated sheets (support layer X1 / electromagnetic shielding layer) according to Examples 2 to 18 and Comparative Examples 1 to 4 were obtained in the same manner except that the blending amounts in Tables 1 to 4 were changed.

[0105] [Examples 19 and 22] A laminate sheet of Example 19 (support layer X2 / electromagnetic shielding layer) and a laminate sheet of Example 22 (support layer X3 / electromagnetic shielding layer) were obtained in the same manner as in Example 1, except that a laminate of support layer X2 or X3 was used instead of support layer X1.

[0106] [Example 20] A laminated sheet of Example 20 (support layer X2 / release layer Y1 / electromagnetic shielding layer) was obtained in the same manner as in Example 19, except that a release layer Y1 was laminated between the support layer X2 and the electromagnetic shielding layer.

[0107] [Example 21] A laminate sheet of Example 21 (support layer X2 / release layer Y1 / electromagnetic shielding layer) was obtained in the same manner as in Example 20, except that the composition was applied so as to give a dry thickness of 50 μm.

[0108] F. Preparation of the resin housing A resin housing made of polycarbonate (manufactured by Takiron C.I. Co., Ltd.) was prepared with dimensions D: 30 mm, W: 50 mm, H: 20 mm, and corner shape R: 2 mm. The thickness of the resin housing was 1 mm.

[0109] G. Evaluation G-1.TOM aptitude The samples were arranged so that the resin housing covering sheet portion (10 cm x 10 cm) of the laminated sheet of each Example and Comparative Example overlapped with the center of the test resin housing, and overlay molding was performed at a set temperature of Tg + 40°C using a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd.). After peeling off the release layer (support layer, or support layer + release layer), post-baking was performed at 130°C for 120 minutes to obtain an electromagnetic wave shielding housing. The appearance of the obtained electromagnetic wave shielding housing was evaluated in terms of wrinkles and tears according to the following criteria.

[0110] G-2.Wrinkles The number and length of wrinkles present in the resin housing covering sheet on the electromagnetic wave shielding housing were measured and evaluated according to the following criteria. +++: The number of wrinkles is 0 to 2, and the length of each wrinkle is less than 5 mm. ++: The number of wrinkles is 3 to 10, and the length of each wrinkle is less than 3 mm. +: The number of wrinkles is 3 to 10, and the length of each wrinkle is 3 mm or more and less than 5 mm. (Practical level) NG: The number of wrinkles is 11 or more, or the length of each wrinkle is 5 mm or more.

[0111] G-3. Torn The number of tears present in the resin housing covering sheet on the electromagnetic wave shielding housing was counted and evaluated according to the following criteria. +++: The number of tears is 0 to 5. ++: The number of tears is between 6 and 10. +: The number of tears is between 11 and 15. (Practical level) NG: There are 16 or more tears.

[0112] G-4. Mold releasability The laminated sheets of each Example and Comparative Example were cut to 25 mm x 100 mm, and a 75 μm thick polyimide film ("Kapton 300H" manufactured by Toray DuPont Co., Ltd.) was superimposed on the resin housing covering sheet side and laminated at 80° C. Next, the obtained sample was peeled between the release layer and the resin housing covering sheet at a peeling speed of 50 mm / min using a tensile tester, and the peeling force was measured. The results were evaluated according to the following criteria. +++: The release layer can be peeled off at the interface between the release layer and the resin housing covering sheet, and the peeling force is 2N / cm or less. ++: Peeling is possible at the interface between the release layer and the resin housing covering sheet, and the peeling force is greater than 2 N / cm and less than 3 N / cm. +: The release layer can be peeled off at the interface between the release layer and the resin housing covering sheet, and the peel strength is greater than 3 N / cm. (Practical level) NG: Peeling is not possible at the interface between the release layer and the plastic housing covering sheet.

[0113] G-5. Adhesion Using a cross-cut guide in accordance with JIS K5400, 100 grids with 1 mm spacing were created on the plastic housing covering sheet on the plastic housing. Then, adhesive tape was firmly pressed onto the grid and the end of the tape was quickly peeled off at a 45° angle, and the condition of the grid was judged according to the following criteria. +++: Peeling rate less than 5%. ++: The plastic housing covering sheet is partially peeled off along the cut line. Peeling rate is 5% or more but less than 10%. +: The plastic housing covering sheet is partially peeled off along the cut line. Peeling rate is 10% or more but less than 15%. NG: The plastic case covering sheet is peeled off partially or entirely along the cut lines. If the peeling rate is 15% or more, it is not suitable for practical use.

[0114] G-6.Electromagnetic wave shielding The laminated sheets of each of the Examples and Comparative Examples were cut to 120 mm x 120 mm, and a 25 μm thick polyimide film ("Kapton 100H" manufactured by Toray DuPont Co., Ltd.) was superimposed on the electromagnetic wave shielding side and laminated at 80° C. Then, after peeling off the peeling layer (support layer, or support layer + release layer), post-baking was performed at 130° C. for 120 minutes, and the electromagnetic wave shielding property was evaluated using an electric field measuring tool at a frequency of 500 MHz by the KEC method, and the electromagnetic wave shielding property was judged according to the following criteria. +++:60dB or more. ++: More than 50dB, less than 60dB. +: More than 40dB, less than 50dB. NG: Less than 40dB. Not practical.

[0115] [Table 1]

[0116] [Table 2]

[0117] [Table 3]

[0118] [Table 4]

[0119] It was confirmed that a covering sheet having a breaking elongation of less than 100% in (i) and / or less than 50% in (ii) has a problem with breaking during processing, as shown in Comparative Examples 1, 3, and 4. It was also confirmed that a covering sheet having a breaking elongation of more than 1500% in (i) and more than 1000% in (ii) has a problem with wrinkling during processing, as shown in Comparative Example 2. In contrast, it was confirmed that the covering sheet of this example, which satisfies all of the above-mentioned (i) to (iii), is excellent in suppressing wrinkling and breaking during processing, and is also excellent in releasability, adhesion, and electromagnetic wave shielding properties.

[0120] In addition, Young's modulus E 1000 and Young's modulus E 50 Ratio of E 1000 / E 50 It was confirmed that the covering sheet having a ratio E of less than 0.7 had a problem with wrinkles during processing, as shown in Comparative Examples 1 and 3. On the other hand, in the range of Tg to Tg+40°C, 1000 / E 50 The present embodiment, which satisfied the ratio E of 0.7 or more, was excellent in suppressing wrinkles and tears during processing, and was also excellent in releasability, adhesion, and electromagnetic wave shielding properties. 1000 / E 50 In Examples 1 to 11, 13 to 17, and 19 to 23, which satisfy the ratio E of 0.8 or more, the evaluation of the inhibition of wrinkles and tears was all ++ or higher, and it was confirmed that they were particularly excellent. 1000 / E 50 was 0.8 or more, |Tg2-Tg1| exceeded 100°C, and therefore the inhibition of wrinkles and tears and the releasability were inferior to those of the above examples which satisfied the condition |Tg2-Tg1|≦100°C. [Explanation of symbols]

[0121] 1 Plastic housing 3 Electromagnetic wave shielding layer 4 Covering sheet 5 Stage 6 Partition 7 Heating source 8 Support layer 9 Release layer 10, 11 Electromagnetic shielding housing 20 Box 21 Lower space 22 Upper space 31 Insulating layer 32 Conductive layer 41 First layer 42 Second layer 43 Third layer 50 Laminated Sheet

Claims

1. A resin housing covering sheet for forming an electromagnetic wave shielding layer of an electromagnetic wave shielding housing, the electromagnetic wave shielding layer including a resin housing and an electromagnetic wave shielding layer covering at least a part of the resin housing, (i) the plastic housing covering sheet at room temperature is placed in a temperature range of Tg to Tg+40° C. of the plastic housing covering sheet, and the breaking elongation measured at the temperature and at a tensile speed of 50 mm / min is 100 to 1500%, (ii) the resin housing covering sheet at room temperature is placed in a temperature range of Tg to Tg+40° C. of the resin housing covering sheet, and the breaking elongation measured at the temperature and at a tensile speed of 1000 mm / min is 50 to 1200%, and further (iii) The plastic housing covering sheet has a puncture strength α per unit film thickness at 23 ° C. measured in a puncture test in accordance with JIS Z1707:2019 of 5 to 150 N / mm.

2. The plastic housing covering sheet at room temperature is subjected to an arbitrary measurement temperature T Ｍ The measured temperature T Ｍ Young's modulus E measured at a tensile speed of 50 mm / min ５０ and the measured temperature T Ｍ Young's modulus E measured at a tensile speed of 1000 mm / min １０００ Comparison with E １０００ / E ５０ The plastic housing covering sheet according to claim 1 , wherein the thickness of the plastic housing covering sheet is 0.7 or more.

3. Contains a thermosetting resin and a curable compound, The curable compound is 2. The resin housing covering sheet according to claim 1, further comprising a curable compound (c) having a hydroxyl group, a secondary amino group, or a tertiary amine group, and having a di- or higher functional epoxy group.

4. A laminate sheet comprising a support layer and the resin housing covering sheet according to claim 1.

5. The laminate sheet according to claim 4 , further comprising a release layer between the support layer and the resin housing covering sheet.

6. The Tg of the support layer is Tg ２ and the Tg of the resin housing covering sheet is Tg １ When |Tg ２ -Tg １ |≦100℃ 5. The laminated sheet according to claim 4, wherein the relationship is:

7. An electromagnetic wave shielding housing comprising a resin housing and an electromagnetic wave shielding layer covering at least a portion of the resin housing, 4. An electromagnetic wave shielding casing, wherein the electromagnetic wave shielding layer is a layer formed using the resin casing covering sheet according to claim 1.

8. A method for manufacturing an electromagnetic wave shielding housing including a resin housing and an electromagnetic wave shielding layer covering at least a portion of the resin housing, comprising: A coating process for forming the electromagnetic wave shielding layer using the resin housing covering sheet according to any one of claims 1 to 3, A method for manufacturing an electromagnetic wave shielding housing, wherein the covering step is carried out by any one of a TOM molding method, a vacuum molding method, a pressure molding method, a vacuum pressure molding method, a press molding method, and an injection molding method.

9. A method for manufacturing an electromagnetic wave shielding housing including a resin housing and an electromagnetic wave shielding layer covering at least a portion of the resin housing, comprising: A coating step of forming the electromagnetic wave shielding layer using the laminated sheet according to any one of claims 4 to 6; and removing layers of the laminated sheet other than the electromagnetic wave shielding layer after the covering step, A method for manufacturing an electromagnetic wave shielding housing, wherein the covering step is carried out by any one of a TOM molding method, a vacuum molding method, a pressure molding method, a vacuum pressure molding method, a press molding method, and an injection molding method.

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