Sheet for internally illuminated signs

Abstract

To obtain a laminate structured internal illumination type signboard sheet that is excellent in light transmittance, has no threads or streaks, is also excellent in adhesiveness between layers.SOLUTION: A sheet material comprises: a base fabric composed of warps and wefts that are multifilament yarns having a fineness of 100 to 350 denier, an adhesive layer provided on at least one surface of the base fabric, and a light-diffusing resin layer laminated on the adhesive layer. The adhesive layer has two layers of a first layer on the base fabric side and a second layer on the light-diffusing resin layer side. The first layer contains an urethane resin. The mass ratio of the second layer and the light-diffusing resin layer is (second layer):(light-diffusing resin layer)=1:3 to 1:10. The cover factor (CF) of the base fabric calculated using the following formula is 1000 to 3500. Cover factor (CF)=NW×DW0.5 + NF×DF0.5 However, NW: warp density (pieces / inch) DW: warp fineness (denier) NF: weft density (pieces / inch) DF: weft fineness (denier)SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a sheet for internally illuminated signs. [Background technology]

[0002] Internally illuminated signs are backlit signs that display content using transmitted light from a light source installed behind the display material. Materials used for internally illuminated signs include acrylic resin sheets and film materials (flexible face sheets (FF sheets)). Recently, the use of film materials has been increasing due to their suitability for inkjet printing, durability, and flame resistance.

[0003] Conventional internally illuminated signs often consisted of multiple fluorescent lamps housed in a robust, box-like structure. In contrast, LED lamps have recently been proposed as a light source due to their long lifespan and energy efficiency. While LED lamps offer the aforementioned energy efficiency and long lifespan, they also exhibit greater light directionality and brightness compared to conventionally used fluorescent lamps. Consequently, it has been pointed out that when using conventional film materials for the display material in internally illuminated signs using LED lamps, the threads and weave structure of the base fabric used in the film material may become visible on the sign's surface.

[0004] Therefore, the required characteristics for internally illuminated sign sheets (FF sheets) include ensuring sufficient light transmission while also providing stronger light diffusion, preventing the light source and the weave of the base fabric from being visible.

[0005] A light-diffusing and transparent film material has already been proposed in which a fabric with multifilament yarns as the knitting element is used as the base fabric, and a light-diffusing coating layer formed of an elastomer composition is provided on one or more surfaces of the base fabric, and the light-diffusing coating layer forms a laminated structure with an anchor layer and a top layer (Patent Document 1). As another material, Patent Document 2 describes a material in which a vinyl chloride resin surface layer with a higher surface hardness than the base layer is bonded to at least one side of a vinyl chloride resin base layer. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-197614 [Patent Document 2] Japanese Patent Application Publication No. 7-191619 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the light-diffusing transparent film material described in Patent Document 1 has a thick fiber count of 67.5 tex (675 decitex) for the glass fiber multifilament used in the base fabric, which makes the threads easily visible. For this reason, the light-diffusing transparent film material described in Patent Document 1 is not a sheet for internally illuminated signs that has excellent light transmittance and does not show threads or threads. Furthermore, because it uses glass fibers, it has the disadvantage of generally being more expensive than when synthetic fibers are used.

[0008] Therefore, the present invention aims to provide a laminated sheet for internally illuminated signs that has excellent light transmittance, inconspicuous threads and streaks, and excellent adhesion between each layer. [Means for solving the problem]

[0009] To achieve this objective, the illuminated sign sheet of the present invention is In both cases, the base fabric is composed of warp and weft threads that are multifilament yarns with a fineness of 100 to 350 denier, An adhesive layer provided on at least one surface of the base fabric, Formed from a sheet material having a light-diffusing resin layer laminated on the aforementioned adhesive layer, The adhesive layer has a first layer on the base fabric side and a second layer on the light-diffusing resin layer side. The first layer contains a urethane resin, The mass ratio of the second layer to the light-diffusing resin layer is (second layer):(light-diffusing resin layer) = 1:3 to 1:10, It is characterized in that the cover factor (CF) of the base fabric calculated by the following formula is in the range of 1000 to 3500. Cover factor (CF) = NW × DW 0.5 + NF × DF 0.5 However, NW: warp density (threads / 25.4mm ) DW: warp fineness (denier) NF: weft density (threads / 25.4mm ) DF: weft fineness (denier)

[0010] According to the sheet for an internally illuminated signboard of the present invention, it is preferable that the second layer of the adhesive layer and the light-diffusing resin layer are formed of resins of the same system. And in that case, it is preferable that both the second layer of the adhesive layer and the light-diffusing resin layer are formed of a vinyl chloride resin composition.

Effects of the Invention

[0011] According to the present invention, since the base fabric is composed of warp and weft threads which are both multifilament yarns with a fineness of 100 to 350 denier, and the cover factor (CF) is in the range of 1000 to 3500, even when an LED lamp with strong light directivity and brightness is used as the light source of the internally illuminated signboard, there is an advantage that the shadows of the yarn streaks and the weave pattern of the base fabric do not appear on the surface of the signboard.

Modes for Carrying Out the Invention

[0012] The sheet for an internally illuminated signboard of the present invention is obtained by laminating a base fabric, an adhesive layer, and a light-diffusing resin layer in this order. The adhesive layer is provided on at least one surface of the base fabric. That is, the adhesive layer is laminated on one side of the base fabric, or laminated on both sides of the base fabric respectively.

[0013] The base fabric will be described.

[0014] A woven fabric is used as the base fabric. Synthetic fibers are used as the fibers constituting the woven fabric. Specifically, polypropylene fibers, polyethylene fibers, polyester fibers, nylon fibers, vinylon fibers, aramid fibers, etc. can be mentioned.

[0015] The woven fabric used for the base fabric is preferably plain weave because, due to its woven structure, it does not become bulky and has a form with few surface irregularities. And both the warp and weft threads constituting the base fabric need to be multifilament yarns with a fineness of 100 to 350 denier (111 to 389 decitex). Because if the fineness is less than 100 denier, the fineness is too low and the tear strength of the base fabric becomes low. Also, if it exceeds 350 denier, the fineness is too high and the yarn streaks are likely to be prominent when used as a sheet for an internally illuminated signboard. For this reason, it is more preferable that the fineness of both the warp and weft threads constituting the base fabric is in the range of 150 to 300 denier.

[0016] The base fabric needs to have a cover factor (CF) calculated by the following formula (1) in the range of 1000 to 3500. Cover factor (CF) = NW × DW 0.5 + NF × DF 0.5 (1) However, NW: warp density (ends / 25.4mm ) DW: warp fineness (denier) NF: weft density (picks / 25.4mm ) DF: weft fineness (denier)

[0017] The density of the warp and weft is represented by the number of warp and weft threads per 1 inch (i.e., 25.4 mm) of the base fabric. If the above cover factor is less than 1000, the voids in the base fabric increase, the light diffusibility deteriorates, and the yarn pores also become prominent. On the contrary, if the cover factor exceeds 3500, the texture of the base fabric becomes hard. For this reason, it is more preferable that the cover factor is in the range of 1100 to 2500.

[0018] The base fabric is preferably treated to prevent water intrusion (water absorption prevention) from the cut surface of the illuminated sign sheet by using one or more water-repellent components selected from fluorine-based compounds, silicone-based compounds, and paraffin-based compounds.

[0019] This section describes the light-diffusing resin layer.

[0020] The light-diffusing resin layer is designed to diffuse the light that passes through it. For example, by including titanium dioxide pigment in the thermoplastic resin composition, good light-diffusing properties can be achieved.

[0021] The light-diffusing resin layer is preferably composed of a thermoplastic resin as described above. Specific examples of resins include vinyl chloride resin, vinyl chloride-vinyl acetate copolymer resin, acrylic resin, urethane resin, chlorinated polyethylene resin, ethylene-vinyl acetate copolymer resin, fluorine-containing copolymer resin, and any mixture thereof. Among these, from the viewpoint of versatility, it is preferable that the layer be composed of a vinyl chloride resin composition.

[0022] Let's explain the adhesive layer.

[0023] The adhesive layer is interposed between the base fabric and the light-diffusing resin layer to bond them together. The adhesive layer has a configuration consisting of a first layer on the base fabric side and a second layer on the light-diffusing resin layer side.

[0024] The first layer is made of a material that has excellent adhesion to the base fabric. When treating the fibers of the base fabric to prevent water absorption as described above, the base fabric is treated with a treatment solution that mixes a material with excellent adhesion to the base fabric and the first layer with a water repellent in order to obtain both adhesion to the base fabric and the water absorption prevention properties of the base fabric. For this reason, the first layer of the adhesive layer must contain a urethane resin.

[0025] The second layer of the adhesive layer is made of a material that has excellent adhesion to the light-diffusing resin layer. For this reason, it is preferable that the second layer be made of a resin of the same type as the light-diffusing resin layer. Here, a resin of the same type means a resin in which most of the constituent components and chemical structure are common and the physical properties are similar. This improves the adhesive strength between the two. For example, if the light-diffusing resin layer is made of a vinyl chloride resin composition as described above, it is preferable that the second layer of the adhesive layer is also made of a vinyl chloride resin composition.

[0026] The second adhesive layer can be formed by immersing the base fabric on which the first layer is formed in a liquid thermoplastic resin composition that has excellent adhesion to the light-diffusing resin layer, thereby impregnating the base fabric on which the first layer is formed with the resin composition.

[0027] Furthermore, the second layer of the adhesive layer is formed by impregnation coating obtained by dipping or coating with a liquid thermoplastic resin composition. As the liquid thermoplastic resin, the use of aqueous dispersion forms such as emulsion resins and dispersion resins, paint forms in which thermoplastic resins are solubilized in organic solvents, and vinyl chloride resin paste sols is preferred.

[0028] By using a liquid thermoplastic resin composition, this resin composition can be impregnated into the fine details of the base fabric on which the first layer is formed.

[0029] The adhesion between the first and second layers of the adhesive layer is stronger than the adhesion between the base fabric and the first layer, and stronger than the adhesion between the light-diffusing resin layer and the second layer. This is because both the first and second layers are adhesive layers.

[0030] The mass ratio between the second layer of the adhesive layer and the light-diffusing resin layer must be (second layer):(light-diffusing resin layer) = 1:3 to 1:10. This range ensures that the two layers have an appropriate mass while maintaining good adhesion. If the mass ratio of the light-diffusing resin layer is lower than this range, the resulting illuminated sign sheet will be excessively heavy. Conversely, if the mass ratio of the light-diffusing resin layer is higher than this range, the mass ratio of the second layer of the adhesive layer will be insufficient, resulting in poor adhesion between the second layer and the light-diffusing resin layer.

[0031] Next, I will explain the additives.

[0032] The base fabric, adhesive layer, and light-diffusing resin layer can each contain appropriate amounts of various additives, as long as they do not impair the effects of the present invention. In the present invention, it is preferable to include a plasticizer and / or titanium dioxide pigment as additives.

[0033] It is preferable that the plasticizer is contained in the second layer of the adhesive layer and the light-diffusing resin layer. When both the second layer of the adhesive layer and the light-diffusing resin layer are formed from a vinyl chloride resin composition, it is preferable that the plasticizer is one that makes the vinyl chloride resin more flexible and easier to process. As such plasticizers, those commonly used in the field of polyvinyl chloride films can be used, for example, phthalate plasticizers such as DOP and DINP, as well as dephthalate plasticizers such as 1,2-cyclohexanedicarboxylic acid diisononyl ester and polyester plasticizers; aliphatic dibasic acid diester plasticizers such as dioctyl adipate and dioctyl sebacate; phosphate triester plasticizers such as tricresyl phosphate and trioctyl phosphate; and epoxy plasticizers such as epoxidized soybean oil and epoxy resins. Among these, it is more preferable to use 1,2-cyclohexanedicarboxylic acid diisononyl ester and polyester plasticizers. By using 1,2-cyclohexanedicarboxylic acid diisononyl ester and polyester-based plasticizers, it is possible to suppress the decrease in adhesive strength due to plasticizer bleed-out when a marking film is attached to the surface of a light-diffusing resin layer.

[0034] The addition of titanium dioxide pigment will be explained. By including titanium dioxide pigment in the light-diffusing resin layer, and not including it in the second layer of the adhesive layer, both light diffusion and light transmission effects can be expressed well.

[0035] The illuminated sign sheet of the present invention preferably has a visible light transmittance (JIS Z 8722) of 25-50%, and more preferably 30-45%. This allows the illuminated sign sheet of the present invention to have good light diffusion transmittance. If the visible light transmittance is less than 25%, the illuminance relative to the brightness of the light source will be low, resulting in an inefficient lighting effect. On the other hand, if the visible light transmittance exceeds 50%, the lamp image of the light source may become more conspicuous.

[0036] Next, I will explain the anti-fouling layer.

[0037] An antifouling layer may be formed on the surface of the light-diffusing resin layer, consisting of a paint such as an acrylic resin, a urethane resin, an acrylic / vinyl chloride copolymer resin, a fluoropolymer resin, or a blend of an acrylic resin and a fluoropolymer resin.

[0038] These antifouling layers can be formed by applying a solvent-soluble resin solution, or an emulsion liquid in which the resin is dispersed in an aqueous dispersion medium, using coating methods such as spray coating, gravure coating, or bar coating, and then allowing it to dry. [Examples]

[0039] The methods for measuring and evaluating various physical properties in the following examples and comparative examples were as follows.

[0040] [Visible light transmittance] The visible light transmittance of the illuminated sign sheets for the examples and comparative examples was measured using a spectroscopic colorimeter CM-3600d (manufactured by Konica Minolta) according to JIS Z 8722 condition g.

[0041] [threads] The illuminated sign sheets of the example and comparative example were stretched over a frame measuring 110 cm vertically and 170 cm horizontally using rail-type tensioning hardware. Then, the visibility of thread streaks was visually observed at a distance of 50 cm from the surface of the sheet.

[0042] The term "thread streaks" here refers to the streaky (raised) appearance that can be seen when the warp and weft threads are tensed during the stretching of a sheet for internally illuminated signs. If these thread streaks are noticeable, the appearance becomes unsightly, and problems such as unevenness in inkjet printing and poor adhesion of marking film can occur.

[0043] [Slit eyes] Using the illuminated sign sheets of the examples and comparative examples, a white LED lamp with a total luminous flux of 100 lumens was covered, with a distance of 10 cm between the LED lamp and the sheet. With the LED lamp lit, the sheet was visually inspected at a distance of 50 cm from the surface of the illuminated sign sheet to determine whether the threads were visible or not.

[0044] The term "thread marks" here refers to the streaky unevenness in light transmission that occurs when light from a light source installed on the back of an internally illuminated sign sheet passes through the sheet, due to the difference in transmittance between the warp and weft threads and the gaps. If the thread marks are noticeable, the appearance becomes unsightly.

[0045] [Adhesiveness] Measurements were taken using a Scott-type testing machine (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) in accordance with JIS K 6404-4:2015. Specifically, a 19.6N load was applied and 200 kneading tests were performed, and the presence or absence of abnormalities such as delamination between the adhesive layer and the light-diffusing coating layer and the base fabric was visually inspected. Adhesion was evaluated as good if no abnormalities such as delamination were observed, and as poor if abnormalities such as delamination were observed.

[0046] (Example 1) Plain weave fabric using 250 denier (278 decitex) multifilament yarn made of polyester fiber for both warp and weft (weave density: 52 warp threads / 25.4mm , 48 weft threads / 25.4mm Coverage factor: 1581, Mass: 107 g / m² 2 ) was used as the base fabric.

[0047] The base fabric was immersed in an aqueous treatment solution containing 3% by mass of a fluorine-based water repellent and 7% by mass of a urethane resin emulsion, allowing it to be impregnated with the solution. Afterward, it was squeezed with a mangle and heated at 180°C for 1 minute. This formed the first adhesive layer, containing the urethane resin, on both sides of the base fabric. The basis weight of the first layer was 13 g / m². 2 That was the case.

[0048] Next, in order to form the second layer of the adhesive layer on the surface of the first layer of the adhesive layer formed on the surface of the base fabric, the base fabric with the first layer formed thereon was immersed in a resin processing solution containing 100 parts by mass of paste vinyl chloride resin, 100 parts by mass of a plasticizer mainly composed of diisononyl 1,2 - cyclohexanedicarboxylate, and an appropriate amount of other commonly used additives (excluding titanium oxide pigment), and the base fabric was impregnated with the resin processing solution. Then, it was heated at 160°C for 1 minute to form the second layer of the adhesive layer on the surface of each first layer formed on both sides of the base fabric. The basis weight of the second layer was adjusted so that the total solid content on both sides of the base fabric was 50 g / m 2 was adjusted.

[0049] Furthermore, a light - diffusing resin layer was formed on the surface of each second layer of the adhesive layer. First, a raw material containing 100 parts by mass of straight vinyl chloride resin, 48 parts by mass of a plasticizer mainly composed of diisononyl 1,2 - cyclohexanedicarboxylate, 0.8 parts by mass of titanium oxide pigment, and an appropriate amount of other commonly used additives was mixed with a Henschel mixer, and the resulting mixture was kneaded to prepare a light - diffusing resin composition. Next, a calender - formed film with a thickness of 0.13 mm made of the light - diffusing resin composition was thermocompression - bonded to the surface of each second layer of the adhesive layer.

[0050] As described above, a sheet with a thickness of 0.40 mm and a mass of 496 g / m 2 was obtained. The basis weight of the light - diffusing resin layer was 326 g / m 2 on both sides. Also, the mass ratio of the second layer of the adhesive layer to the light - diffusing resin layer was (second layer):(light - diffusing resin layer)=1:6.52.

[0051] Then, an acrylic resin paint was applied to the surface of each of the light - diffusing resin layers on both sides by a gravure roll and heated at 120°C for 1 minute to form an antifouling layer. As a result, finally, a sheet with a thickness of 0.40 mm and a mass of 500 g / m 2 was obtained.

[0052] The properties of the obtained sheet are shown in Table 1.

[0053] [Table 1]

[0054] (Comparative Example 1) Compared to Example 1, the difference is that a second adhesive layer is not provided, and the same light-diffusing resin composition used in Example 1 is heat-pressed onto both sides of the first adhesive layer as a light-diffusing resin layer, using a calendered film with a thickness of 0.14 mm. The basis weight of the heat-pressed light-diffusing resin composition is 366 g / m². 2 The other specifications were the same as in Example 1, with a thickness of 0.39 mm and a mass of 486 g / m². 2 A sheet was obtained. An antifouling layer similar to that in Example 1 was laminated onto the surface of each light-diffusing resin layer in this sheet, resulting in a sheet with a thickness of 0.39 mm and a mass of 490 g / m². 2 I obtained the sheet.

[0055] The characteristics of the obtained sheets are shown in Table 1.

[0056] (Comparative Example 2) Plain weave fabric using 500 denier (556 decitex) multifilament yarn made of polyester fiber for both warp and weft (weave density: 21 warp threads / 25.4mm , 19 weft threads / 25.4mm Coverage factor: 898, Mass: 93g / m² 2 ) was used as the base fabric.

[0057] The base fabric was immersed in an aqueous treatment solution containing 1% by mass of a fluorine-based water repellent, allowing it to be impregnated with the solution. Afterward, it was squeezed with a mangle and heated at 180°C for 1 minute. As a result, both sides of the base fabric were treated with a urethane resin-free material with a basis weight of 1 g / m². 2 An adhesive layer was formed.

[0058] Next, the same light-diffusing resin composition used in Example 1 was applied to the surface of each of the aforementioned layers that do not contain urethane resin, and then bonded together by heat-pressing to form a calendered film with a thickness of 0.23 mm, resulting in a basis weight of 602 g / m². 2A light-diffusing resin layer was formed. This resulted in a thickness of 0.56 mm and a mass of 696 g / m². 2 A sheet was obtained. Antifouling layers were laminated onto the light-diffusing resin layers on both sides of this sheet, in the same manner as in Example 1. As a result, a sheet with a thickness of 0.56 mm and a mass of 700 g / m² was obtained. 2 I obtained the sheet.

[0059] The characteristics of the obtained sheets are shown in Table 1.

[0060] As shown in Table 1, the sheet of Example 1 had good adhesion and the threads and streaks were not noticeable. The visible light transmittance was also good.

[0061] In contrast, the sheet of Comparative Example 1 lacked a second adhesive layer, resulting in poor adhesion and a slightly lower visible light transmittance compared to Example 1. Visible light transmittance is thought to be influenced by the thickness of the second adhesive layer and the thickness of the light-diffusing resin layer. Since the sheet of Comparative Example 1 lacks a second layer and only has a light-diffusing resin layer, it is thought that the visible light transmittance is slightly lower.

[0062] The sheet in Comparative Example 2 had poor adhesion because it lacked an adhesive layer, and the use of coarse, thick yarn resulted in noticeable thread marks and streaks. Furthermore, the use of coarse, thick yarn also resulted in a greater thickness, leading to a lower visible light transmittance.

Claims

1. In both cases, the base fabric is composed of warp and weft threads that are multifilament yarns with a fineness of 100 to 350 denier, An adhesive layer provided on at least one surface of the base fabric, Formed from a sheet material having a light-diffusing resin layer laminated on the aforementioned adhesive layer, The adhesive layer has a first layer on the base fabric side and a second layer on the light-diffusing resin layer side. The first layer contains a urethane resin, The mass ratio of the second layer to the light-diffusing resin layer is (second layer):(light-diffusing resin layer) = 1:3 to 1:

10. A sheet for internally illuminated signs, characterized in that the cover factor (CF) of the base fabric, calculated by the following formula, is in the range of 1000 to 3500. Coverage Factor (CF) = NW × DW ０．５ +NF×DF ０．５ However, NW: Warp density (threads / 25.4 mm) DW: Warp thread fineness (denier) NF: Weft density (threads / 25.4 mm) DF: Weft yarn fineness (denier)

2. The illuminated sign sheet according to claim 1, characterized in that both the second adhesive layer and the light-diffusing resin layer are formed from a vinyl chloride resin composition.

Images