adhesive tape

Abstract

To provide an adhesive tape that exhibits excellent flame retardancy, insulation properties and color development.SOLUTION: An adhesive tape according to one embodiment of the present invention comprises colored fabric, an intermediate layer, and an adhesive layer. The intermediate layer is laminated on one side of the colored fabric and contains silicon dioxide particles. The adhesive layer is laminated on the intermediate layer. The colored fabric comprises glass cloth and colored fluororesin layers formed on both sides of the glass cloth and containing fluororesin and inorganic pigment.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive tape. [Background technology]

[0002] Conventionally, adhesive tapes made of fluororesin have been used for purposes such as heat resistance, flame retardancy, and insulation. In order to color a fluororesin adhesive tape, for example, a technique of mixing a pigment into the adhesive layer has been adopted. When a transparent or translucent fluororesin film is laminated on a colored adhesive layer, a person observing the adhesive tape can visually recognize the color of the adhesive layer through the fluororesin film.

[0003] One of the reasons for adopting this method is that the high melting point of fluororesin makes it difficult to mix organic pigments into fluororesin films when they are produced or processed. When organic pigments are mixed into fluororesin films that are processed at high temperatures around 300°C, there is a possibility that the organic pigments will carbonize or decompose during processing. Therefore, it has been difficult to color the fluororesin film itself with organic pigments.

[0004] On the other hand, there are cases where adhesive tapes are required to have excellent flame retardancy and insulating properties, such as for covering high-voltage cables. To meet these requirements, there is a demand for adhesive tapes that use fabric-type sheets in which fluororesin is supported on a glass cloth substrate, instead of fluororesin films. In addition, there is a demand for such adhesive tapes to be colored orange or the like, so that workers and others can easily recognize dangerous areas or components to which the adhesive tape is attached. In other words, adhesive tapes used for covering high-voltage cables and the like are required to have not only excellent flame retardancy and insulating properties, but also high color development and be colored orange or the like. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-222137 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pressure-sensitive adhesive tape having excellent flame retardancy, insulating properties and high color development properties. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided an adhesive tape. The adhesive tape comprises a colored fabric, an intermediate layer, and an adhesive layer. The intermediate layer is laminated on one side of the colored fabric and contains silicon dioxide particles. The adhesive layer is laminated on the intermediate layer. The colored fabric comprises a glass cloth and colored fluororesin layers formed on both sides of the glass cloth and containing a fluororesin and an inorganic pigment. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a pressure-sensitive adhesive tape having excellent flame retardancy, insulating properties and high color development properties. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a pressure-sensitive adhesive tape according to an embodiment. [Figure 2] FIG. 1 is a cross-sectional view schematically showing an example of a production line according to an impregnation coating method. DETAILED DESCRIPTION OF THE INVENTION

[0010] In a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on one side of a fabric containing glass cloth, even if the pressure-sensitive adhesive layer is colored, the visibility of the color of the pressure-sensitive adhesive layer through the fabric is poor. One reason for this is that, for example, the presence of the glass cloth makes it difficult for an observer to see the reflected light emitted from the pressure-sensitive adhesive layer.

[0011] The present inventors attempted to color the fabric itself, particularly the fluororesin contained in the fabric, rather than coloring the adhesive layer, as has been conventionally done. The processing temperature of fluororesin is high. In the case of PTFE, the processing temperature can be, for example, 343°C or higher. Therefore, even if an organic pigment is mixed with the fluororesin to enhance the color development of the fabric, the organic pigment will carbonize or decompose, as described above. In particular, most pigments used to develop an orange color to alert workers and others to danger are organic pigments. Therefore, it has been difficult to color fabric orange with high color development.

[0012] (First embodiment) According to an embodiment, an adhesive tape is provided. The adhesive tape comprises a colored fabric, an intermediate layer, and an adhesive layer. The intermediate layer is laminated on one side of the colored fabric and contains silicon dioxide particles. The adhesive layer is laminated on the intermediate layer. The colored fabric comprises a glass cloth and colored fluororesin layers formed on both sides of the glass cloth and containing a fluororesin and an inorganic pigment.

[0013] The pressure-sensitive adhesive tape according to the embodiment comprises a colored fabric having a glass cloth core and colored fluororesin layers formed on both sides of the glass cloth core. The colored fluororesin layers are colored with an inorganic pigment. Therefore, the color tone of the pigment is not easily lost even during the preparation of the colored fluororesin layers. Furthermore, because the colored fabric comprises glass cloth, the pressure-sensitive adhesive tape exhibits excellent flame retardancy and insulating properties.

[0014] This adhesive tape will be described in detail below with reference to the drawings.

[0015] FIG. 1 is a cross-sectional view schematically illustrating an example of a pressure-sensitive adhesive tape according to an embodiment. The adhesive tape 10 comprises a colored fabric 1, an intermediate layer 4, and an adhesive layer 5. The colored fabric 1 comprises a glass cloth 2 and colored fluororesin layers 3 formed on both sides thereof. Although not explicitly shown in FIG. 1 , the colored fluororesin layer 3 contains a fluororesin and an inorganic pigment.

[0016] The colored fabric 1 has two main surfaces. One of the two main surfaces of the colored fabric 1 is exposed, and an intermediate layer 4 and a pressure-sensitive adhesive layer 5 are laminated in this order on the other surface. In the present specification and claims, the exposed side of the two main surfaces of the colored fabric 1 is referred to as the "front side," and the unexposed side is referred to as the "back side."

[0017] The intermediate layer 4 is provided on at least a portion of the back surface of the colored fabric 1. In the example shown in FIG. 1, the intermediate layer 4 is provided on the entire back surface of the colored fabric 1. The adhesive layer 5 is provided on at least a portion of the front surface of the intermediate layer 4. In the example shown in FIG. 1, the adhesive layer 5 is provided on the entire front surface of the intermediate layer 4.

[0018] (1) Colored fabric The colored fabric 1 can be, for example, a sheet or film having a predetermined thickness. The thickness of the colored fabric 1 is not particularly limited, but is, for example, in the range of 50 μm to 300 μm. If the colored fabric 1 is excessively thick, the adhesive tape will have too much rigidity and will lose its flexibility as an adhesive tape, which is not preferred. If the colored fabric 1 is excessively thin, the tensile strength will be insufficient, making the adhesive tape prone to breakage, which is also not preferred.

[0019] The thickness of the glass cloth is, for example, in the range of 25 μm to 200 μm, and preferably in the range of 50 μm to 150 μm. When the thickness of the glass cloth is within this range, good workability can be obtained, for example, when covering a cable or the like with adhesive tape. In addition, costs can be reduced.

[0020] The mass per unit area of ​​the glass cloth is, for example, 25 g / m 2 ~200g / m 2 The yarn density of the glass cloth is, for example, within the range of 30 yarns / 25 mm to 80 yarns / 25 mm. The yarn density in the longitudinal direction of the glass cloth may be different from the yarn density in the transverse direction. The TEX count per glass fiber yarn is, for example, within the range of 5 g / 1000 m to 80 g / 1000 m.

[0021] The fluororesin contained in the colored fluororesin layer 3 is, for example, at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylenepropene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer (ETFE). The type of fluororesin contained in the colored fluororesin layer 3 may be one type, or a mixture of two or more types. Among these, it is preferable that the colored fluororesin layer 3 contains PTFE as the fluororesin because it has excellent heat resistance as well as high chemical resistance. The fluororesin contained in the colored fluororesin layer 3 may be PTFE alone.

[0022] When the colored fluororesin layer 3 contains PTFE, the PTFE exists as a sintered body of resin particles. The average primary particle diameter of the PTFE resin particles is, for example, in the range of 0.02 μm to 0.5 μm, and preferably in the range of 0.1 μm to 0.3 μm. The average primary particle diameter of the PTFE resin particles can be measured using a transmission electron microscope (TEM).

[0023] The colored fluororesin layer 3 may further contain an additive. The additive is added, for example, when producing a colored fabric, for the purpose of increasing the dispersibility of the inorganic pigment in the dispersion or increasing the wettability of the dispersion. The additive is, for example, a surfactant. Examples of the additive include heptamethyl-3-(propyl(polyethylene oxide)methyl)trisiloxane and allyloxypolyethylene glycol methyl ether. The method for producing the pressure-sensitive adhesive tape will be described later.

[0024] Since the colored fluororesin layer 3 is colored with an inorganic pigment, the surface of the colored fabric 1 has a color tone similar to that of the colored fluororesin layer 3 itself. Strictly speaking, the color of the surface of the colored fabric 1 is determined by the mass (basis weight [g / m2]) of the glass cloth 2 contained per unit area of ​​the colored fabric 1. 2 ]), the mass of the colored fluororesin layer 3 contained per unit area of ​​the colored fabric 1 (basis weight [g / m 2 ]), and the mass of the inorganic pigment contained per unit area of ​​the colored fluororesin layer 3 (basis weight [g / m 2 ]) etc.

[0025] In the present specification and claims, the mass per unit area of ​​the colored fabric itself is represented by M1, the mass per unit area of ​​the colored fluororesin layer is represented by M2, and the mass per unit area of ​​the inorganic pigment contained in the colored fluororesin layer is represented by M3.

[0026] The mass per unit area of ​​the colored fabric, M1, is the sum of the mass per unit area of ​​the glass cloth and the mass per unit area of ​​the colored fluororesin layer, M2. The mass per unit area of ​​the colored fluororesin layer, M2, is the sum of the mass per unit area of ​​the fluororesin contained in the colored fluororesin layer and the mass per unit area of ​​the inorganic pigment contained in the colored fluororesin layer, M3.

[0027] <Measuring method for mass per unit area M1, M2 and M3> First, the mass of the colored fabric cut into 10mm x 10mm pieces is measured. This measurement determines the mass per unit area of ​​the colored fabric, M1. Next, the colored fabric whose mass has been measured is cut into small pieces and placed in a crucible. The crucible is heated to burn the fluororesin. The mass of the residue obtained after combustion is measured, and by subtracting the mass of the glass cloth having a size of 10mm x 10mm, the mass per unit area of ​​the inorganic pigment, M3, is calculated. Furthermore, by subtracting the mass of the glass cloth having a size of 10mm x 10mm from the previously measured mass, M1, the mass per unit area of ​​the colored fluororesin layer, M2, can be measured. Furthermore, by subtracting the mass per unit area of ​​the inorganic pigment, M3, from the mass per unit area of ​​the colored fluororesin layer, M2, the mass per unit area of ​​the fluororesin contained in the colored fluororesin layer can be calculated.

[0028] The mass per unit area of ​​the colored fabric, M1, is, for example, 50.0 g / m 2 ~600g / m 2 and preferably within the range of 80 g / m 2 ~300g / m 2 If the mass M1 per unit area is within this range, it is possible to improve the workability when, for example, winding the adhesive tape around a cable or the like.

[0029] The mass M2 per unit area of ​​the colored fluororesin layer is, for example, 25.0 g / m 2 ~90.0g / m 2 and preferably in the range of 60.0 g / m 2 ~70.0g / m 2The mass per unit area of ​​the colored fluororesin layer, M2, is within the range of 0.01 to 0.01. If the mass per unit area of ​​the colored fluororesin layer, M2, is excessively low, it means that the amounts of fluororesin and inorganic pigment supported on both sides of the glass cloth are small. Therefore, it is difficult to obtain color development due to the inorganic pigment, and the color tone of the glass cloth itself is easily observed. On the other hand, increasing the mass per unit area of ​​the colored fluororesin layer, M2, gradually eliminates the influence of the glass cloth on the color tone of the surface of the colored fabric. When M2 reaches a certain value, the color tone of the surface of the colored fabric generally becomes similar to the color tone of the colored fluororesin layer itself. Therefore, even if M2 is excessively increased, the color of the surface of the colored fabric is unlikely to change once it exceeds a certain value. However, the mass per unit area of ​​the colored fluororesin layer, M2, may be changed not for the purpose of changing the color tone but for the purpose of adjusting the mechanical strength, etc., of the adhesive tape. For example, the mass per unit area of ​​the colored fluororesin layer, M2, can be increased to increase the rigidity of the adhesive tape.

[0030] The mass M3 per unit area of ​​the inorganic pigment contained in the colored fluororesin layer is, for example, 1.0 g / m 2 ~5.0g / m 2 and preferably in the range of 2.5 g / m 2 ~4.5g / m 2 If the mass M3 per unit area of ​​the inorganic pigment contained in the colored fluororesin layer is small, it is difficult to make the color tone of the inorganic pigment appear on the surface of the colored fabric. However, if the amount of fluororesin contained per unit area of ​​the colored fluororesin layer is small, it is easy to make the color tone of the inorganic pigment appear even if M3 is small.

[0031] By calculating the ratio M3 / M2 of the inorganic pigment mass per unit area M3 to the colored fluororesin layer mass per unit area M2, the mass of the inorganic pigment relative to the fluororesin mass within a given area can be evaluated. The higher the ratio M3 / M2, the higher the mass of the inorganic pigment contained within a given area, and therefore an observer observing the colored fabric will perceive a color closer to the color of the inorganic pigment itself. The lower the ratio M3 / M2, the lower the mass of the inorganic pigment contained within a given area, and therefore, an observer observing the colored fabric will perceive a color closer to the color of the fluororesin itself.

[0032] The ratio M3 / M2 of the mass per unit area of ​​the inorganic pigment M3 to the mass per unit area of ​​the colored fluororesin layer M2 is, for example, in the range of 0.03 to 0.10, preferably in the range of 0.04 to 0.07. If the ratio M3 / M2 is excessively low, it is difficult to obtain excellent color development. If the ratio M3 / M2 is excessively high, the properties of the fluororesin tend to be impaired. By adjusting the ratio M3 / M2 to the range of 0.03 to 0.10, it is possible to suppress variations in color tone on the surface of the colored fabric.

[0033] In the colored fluororesin layer 3, the mass ratio of the fluororesin to the inorganic pigment is, for example, in the range of 91:9 to 98:2, and preferably in the range of 96:4 to 94:6. When the mass ratio is within this range, excellent color development can be obtained while maintaining the properties of the fluororesin (for example, flame retardancy and insulating properties).

[0034] As the inorganic pigment, various inorganic pigments can be used depending on the application of the pressure-sensitive adhesive tape. That is, the type of inorganic pigment can be appropriately changed depending on the color tone to be expressed in the colored fabric.

[0035] In order to impart a color tone that alerts an observer viewing the pressure-sensitive adhesive tape to the risk of danger, it is preferable to use an inorganic pigment having an orange hue. In order to color the colored fluororesin layer orange, it is preferable to use at least one inorganic pigment selected from the group consisting of a complex oxide containing tin, titanium, tungsten, and zinc, and a complex oxide containing chromium, iron, cobalt, copper, and manganese. The use of these inorganic pigments has the advantages of excellent dispersion stability and the reddish color that is not easily burned off even when heated during the preparation of the colored fluororesin layer.

[0036] The median diameter of the inorganic pigment is not particularly limited, but is, for example, in the range of 0.1 μm to 2.0 μm. When the median diameter of the inorganic pigment for producing an orange color is within this range, the dispersion stability is enhanced, and the color development properties are improved.

[0037] The surface color of the colored fabric is as follows: * a * b * It can be expressed in the color system. * a * b * A color system is an index used to represent the color of an object. * a * b * The color system is an index standardized by the International Commission on Illumination (CIE) in 1976, and in Japan it is adopted in the Japanese Industrial Standard JIS Z 8781-4. * a * b * In the color space, L * represents the brightness, and a * and b * represents the hue and saturation of the color. * The larger the value, the higher the brightness. * and b * indicates the direction of the color. * indicates the red direction, and -a * indicates the green direction. * indicates the yellow direction, and -b *indicates the blue direction. The saturation is indicated by the letter c * It is expressed as (c * )=((a * ) 2 +(b * ) 2 ) 1 / 2 It is calculated as follows.

[0038] Regarding the surface color of the colored fabric, L * is, for example, in the range of 59.0 to 62.0. * is, for example, in the range of 18.0 to 27.0, and preferably in the range of 20.0 to 24.0. * is, for example, in the range of 25.0 to 55.0, and preferably in the range of 40.0 to 50.0. * is in the range of 59.0 to 62.0, and a * is in the range of 18.0 to 27.0 and b * When L is within the range of 25.0 to 55.0, it is possible to develop a good orange color. * is in the range of 59.0 to 62.0, and a * is in the range of 20.0 to 24.0 and b * If the value is within the range of 40.0 to 50.0, it can be said that the colored fabric has excellent visibility and an excellent orange color tone.

[0039] In order to produce an orange color with excellent visibility, it is preferable that the surface of the colored fabric has a certain level of redness. * is preferably 20.0 or more. If an organic pigment is used as the pigment contained in the colored fluororesin layer to produce an orange color, the organic pigment will not be able to withstand the processing temperature of the fluororesin, and the reddish color will tend to disappear. The colored fluororesin layer may further contain an organic pigment, but it is not necessary to do so. Since the colored fluororesin layer according to the embodiment contains an inorganic pigment, it is possible to suppress the disappearance of the reddish color due to the processing temperature, as described above.

[0040] Coloring the surface color of the fabric * a* b * To measure in the color system, a spectrophotometer CM-5 and a color difference meter CR-5 manufactured by KONICA MINOLTA, or a device with equivalent functions, can be used. This device allows measurements in accordance with the Japanese Industrial Standard JIS Z 8781-4. When measuring the color of the surface of a colored fabric, the L * , a * and b * The values ​​are measured at 10 positions, and the average value (simple average) is calculated.

[0041] (2) Middle Class The intermediate layer 4 is laminated on one side of the colored fabric 1. The intermediate layer 4 contains silicon dioxide particles. The intermediate layer 4 may further contain a fluororesin and an active agent.

[0042] The silicon dioxide particles contained in the intermediate layer 4 reduce the non-stickiness of the back surface of the highly non-stick colored fabric 1. Therefore, by having the intermediate layer 4 between the colored fabric 1 and the adhesive layer 5, it is possible to prevent the adhesive layer 5 (and the intermediate layer 4) from peeling off from the colored fabric 1.

[0043] The thickness of the intermediate layer 4 is not particularly limited, but is within the range of 1 μm to 30 μm, for example.

[0044] The fluororesin that can be contained in the intermediate layer 4 can be the same as the fluororesin described as the fluororesin contained in the colored fluororesin layer 3. The fluororesin contained in the colored fluororesin layer 3 can be called the first fluororesin. The fluororesin contained in the intermediate layer 4 can be called the second fluororesin. The second fluororesin contained in the intermediate layer 4 may be of one type, or two or more types may be mixed. The second fluororesin contained in the intermediate layer 4 and the first fluororesin contained in the colored fluororesin layer 3 may be the same type or different types.

[0045] When the second fluororesin that can be contained in the intermediate layer 4 contains a melt-flowable fluororesin, it is possible to further improve the fusion property between the colored fabric 1 and the pressure-sensitive adhesive layer 5. Here, the melt-flowable fluororesin is at least one selected from the group consisting of perfluoroalkoxyalkane (PFA), perfluoroethylenepropene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer (ETFE).

[0046] The silicon dioxide particles (SiO2) are preferably amorphous silica, and more preferably hydrophilic amorphous silica.

[0047] Silicon dioxide particles have a specific surface area of ​​10 m according to the Brunauer, Emmett, Teller (BET) adsorption isotherm. 2 / g or more. 2 By making the viscosity at least 50 m / g, the adhesiveness between the colored fabric and the adhesive layer can be improved. 2 / g or more 400m 2 / g or less.

[0048] The average primary particle size of the silicon dioxide particles is preferably in the range of 5 nm to 80 nm, more preferably in the range of 7 nm to 40 nm. The average primary particle size of the silicon dioxide particles can be measured by TEM observation.

[0049] The mass ratio of silicon dioxide particles to the mass of the intermediate layer is preferably in the range of 0.5% by mass or more and 30% by mass or less. By making this ratio 0.5% by mass or more, the adhesion between the colored fabric and the adhesive layer can be improved. If this ratio is increased, the adhesion between the colored fabric and the adhesive layer will be improved, but the brittleness of the intermediate layer will increase, which may reduce the flexibility of the adhesive tape. By making this ratio 30% by mass or less, the adhesive tape will have excellent flexibility. A more preferred range for this ratio is 5% by mass or more and 20% by mass or less.

[0050] The mass ratio of the fluororesin to the mass of the intermediate layer is, for example, in the range of 70 mass % to 99.5 mass %.

[0051] The surfactant that the intermediate layer may contain is, for example, at least one selected from an anionic surfactant and a nonionic surfactant, which has the effect of improving leveling properties and wettability.

[0052] (3) Adhesive layer The adhesive layer 5 is a layer having adhesiveness and contains, for example, an adhesive and a curing agent.

[0053] The thickness of the pressure-sensitive adhesive layer 5 is not particularly limited, but is within the range of 25 μm to 80 μm, for example.

[0054] The adhesive may be at least one selected from a natural rubber adhesive, a silicone adhesive, and an acrylic adhesive, among which, from the viewpoint of heat resistance, it is preferable that the adhesive contains a silicone adhesive and / or an acrylic adhesive.

[0055] Examples of silicone-based adhesives include peroxide-curing adhesives and addition-curing adhesives. When a peroxide-curing adhesive is used as the adhesive, at least one selected from the group consisting of benzoyl peroxide, dicumyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and di-t-butyl peroxide can be used as the curing agent. When an addition-curing adhesive is used as the adhesive, platinum, for example, can be used as the curing agent.

[0056] (4) Adhesive tape The thickness of the adhesive tape 10 is not particularly limited, but is, for example, in the range of 80 μm to 250 μm.

[0057] In one example, the thickness of the adhesive tape 10 is accounted for by the colored fabric 1, the intermediate layer 4, and the adhesive layer 5, each accounting for 63% to 73%, 0.5% to 2%, and 27% to 34%, respectively. The thickness of each layer may deviate from these ratios, but ensuring that the thickness of each layer satisfies these ratios ensures stable mechanical strength and adhesiveness. In this case, the adhesive tape is suitable for cable coating. The thickness of each layer can be measured, for example, by observing a cross section of the adhesive tape using a scanning electron microscope (SEM).

[0058] The pressure-sensitive adhesive tape according to the embodiment can be used, for example, for covering high-voltage cables and conductors, etc., and as a release pressure-sensitive adhesive tape, etc. The release pressure-sensitive adhesive tape can be used in heat sealing machines, vacuum packaging machines, etc., and in resin molding processes.

[0059] <Manufacturing method> Next, an example of a method for manufacturing the pressure-sensitive adhesive tape according to the embodiment will be described.

[0060] <Production of colored fabric> The colored fabric can be produced, for example, by the impregnation coating method described below. In the impregnation coating method, a colored fabric is produced in which a colored fluororesin layer is formed on both sides of a glass cloth. FIG. 2 is a cross-sectional view schematically showing an example of an apparatus and production line for impregnating a glass cloth as a core material with a fluororesin and an inorganic pigment. Here, as an example, a case where the fluororesin is PTFE resin particles will be described.

[0061] In the figure, reference numeral 30 denotes a delivery roll that delivers glass cloth 31, which is the substrate. Downstream of the delivery roll 30, an impregnation tank 33 filled with an aqueous dispersion 32 is arranged. At least PTFE resin particles and inorganic pigment particles are dispersed in the aqueous dispersion 32. The aqueous dispersion 32 may further contain additives, etc. The dispersion for forming the colored fluororesin layer will be referred to as the first dispersion for convenience. As will be described later, the dispersion for forming the intermediate layer will be referred to as the second dispersion for convenience.

[0062] In order to increase the dispersion stability of the inorganic pigment particles and improve the color development of the colored fabric, the inorganic pigment particles may be subjected to a pulverization treatment using a bead mill or the like before being added to the dispersion liquid.

[0063] A pair of doctor rolls 35 are arranged above the impregnation tank 33. Above the doctor rolls 35, a heating furnace 7 is arranged, which is divided into three blocks with different heat treatment temperatures. The heating furnace 7 is divided into three blocks, from the bottom up: a drying section 7a, a heat treatment section 7b, and a baking section 7c, and is controlled to have a temperature distribution in which the temperature increases sequentially from the drying section 7a to the baking section 7c. Downstream of the heating furnace 7, rolls 34c, 34d, and 34e and a take-up roll 9 are arranged.

[0064] Using the apparatus having the above-described configuration, a colored fluororesin layer is formed on a glass cloth in the following procedure.

[0065] First, the glass cloth 31 wound around the delivery roll 30 is sent to the side of the roll 34b, which is placed in the impregnation tank 33 and in the aqueous dispersion 32, and the aqueous dispersion 32 is applied to the glass cloth 31. Next, a pair of doctor rolls 35 is used to scrape off excess aqueous dispersion 32 applied to both sides of the glass cloth 31. Subsequently, the glass cloth 31 coated with the aqueous dispersion 32 is sent to the drying section 7a of the heating furnace 7, where the coated aqueous dispersion 32 is dried at a temperature of 100°C or less to evaporate the water in the aqueous dispersion. Next, the glass cloth 31 is sent to the heat treatment section 7b, where it is slowly heated at a temperature of, for example, 305°C or higher to remove additives and the like in the aqueous dispersion 32.

[0066] In the subsequent baking section 7c, baking may or may not be performed. If baking is performed in the baking section 7c, the baking temperature is set to a temperature equal to or higher than the melting point of the PTFE resin. The baking temperature is set to, for example, a range of 320°C to 340°C. The laminate 8 that has passed through the baking section 7c is taken up on a take-up roll 9 via rolls 34c, 34d, and 34e. In this way, a colored fabric is obtained in which colored fluororesin layers are formed on both sides of the glass cloth. When forming the colored fluororesin layers, the above-mentioned series of impregnation coating methods may be repeated to perform multiple coatings.

[0067] The amount of colored fluororesin layer carried on both sides of the glass cloth and the color tone of the surface of the colored fabric can be appropriately adjusted by adjusting the composition of the first dispersion, the number of times of impregnation coating, etc. In other words, the mass M1 per unit area of ​​the colored fabric, the mass M2 per unit area of ​​the colored fluororesin layer, and the mass M3 of the inorganic pigment contained per unit area of ​​the colored fluororesin layer 3 can each be adjusted to a desired value by adjusting the composition of the first dispersion, the number of times of impregnation coating, etc.

[0068] The first dispersion liquid contains, for example, fluororesin particles at a solid content concentration of 45.0% to 60.0% by mass and inorganic pigment at a solid content concentration of 1.0% to 10.0% by mass. The solid content concentration of the fluororesin is preferably in the range of 50.0% to 55.0% by mass. The solid content concentration of the inorganic pigment is preferably in the range of 2.0% to 4.0% by mass. The additive may be contained in the first dispersion liquid at a concentration of, for example, 0.5% to 1.5% by mass.

[0069] <Formation of the intermediate layer> Next, an intermediate layer is formed on at least a portion of the back surface of the obtained colored fabric. As an example of a method for forming the intermediate layer, an impregnation coating method can be used, as in the formation of the colored fabric described above.

[0070] An aqueous dispersion containing silicon dioxide particles and fluororesin particles is prepared as a dispersion for forming an intermediate layer (second dispersion). An intermediate layer can be formed on one side (rear side) of the colored fabric using an apparatus similar to that shown in Figure 2.

[0071] Instead of the glass cloth 31, the colored fabric 1 is wound around the unwinding roll 30. Also, instead of the first dispersion, a second dispersion is prepared in the impregnation tank 33. The doctor roll 35 is changed to one that can scrape off as much of the second dispersion as possible from the surface of the colored fabric 1. Apart from these changes, the intermediate layer can be formed by performing impregnation coating in the same manner as in the formation of the colored fabric described above.

[0072] The second dispersion contains, for example, silicon dioxide particles at a solid content concentration of 0.1% to 20% by mass, and fluororesin particles at a solid content concentration of 1% to 30% by mass.

[0073] <Formation of adhesive layer> Thereafter, a pressure-sensitive adhesive layer is formed on the intermediate layer according to a known method. The pressure-sensitive adhesive layer can be formed, for example, by preparing a pressure-sensitive adhesive solution containing a pressure-sensitive adhesive and a curing agent, applying this solution to the intermediate layer, and then heat-treating the solution. Examples of solvents used for this solution include toluene and xylene.

[0074] The content of the curing agent in the adhesive-containing solution is, for example, in the range of 0.1% by weight to 15% by weight.

[0075] The viscosity of the solution for forming the adhesive layer is, for example, in the range of 1000 cP to 100000 cP.

[0076] The adhesive layer is formed by applying a heat treatment to harden the adhesive after the application of the adhesive-containing solution. This heat treatment is carried out, for example, at a temperature in the range of 160°C to 220°C for 120 to 600 seconds.

[0077] A pressure-sensitive adhesive tape can be produced in the manner described above. Since the pressure-sensitive adhesive layer is provided on only one side of this pressure-sensitive adhesive tape, it can be wound into a roll after the pressure-sensitive adhesive layer is formed. After the pressure-sensitive adhesive layer is formed, a release paper may be attached to the pressure-sensitive adhesive layer.

[0078] [Example] Examples will be described below, but the embodiments are not limited to the examples described below.

[0079] Example 1 <Production of colored fabric> First, a strip-shaped, long glass cloth with a thickness of 55 μm was prepared. This glass cloth had a mass per unit area of ​​48 g / m. 2 The yarn density in the warp direction was 60 / 25 mm, the yarn density in the weft direction was 46 / 25 mm, and the TEX count of both the warp and weft was 11 g / 1000 m.

[0080] The impregnation coating described with reference to FIG. 2 was repeated multiple times on the glass cloth. A first dispersion was used, in which PTFE resin particles, inorganic pigment particles, and a surfactant were dispersed in water as a solvent. The PTFE resin particles were an aqueous dispersion (solid content concentration: 60% by mass) manufactured by Mitsui Chemours Fluoro Products, Inc. The inorganic pigment particles were a composite oxide containing tin, titanium, tungsten, and zinc to impart an orange color to the colored fabric. The median diameter of the inorganic pigment particles was 0.3 μm. The masses of the PTFE resin particles, inorganic pigment particles, and surfactant in the first dispersion were 85.0% by mass, 5.1% by mass, and 0.6% by mass, respectively.

[0081] By repeating the impregnation coating several times, a colored fabric was obtained in which a colored fluororesin layer was formed on both sides of the glass cloth.

[0082] <Formation of the intermediate layer> PFA resin particles, silicon dioxide particles, and an activator were dispersed in water as a solvent to prepare a dispersion for forming an intermediate layer (second dispersion). The second dispersion was used to carry out the impregnation coating described with reference to FIG. 2. The masses of the fluororesin particles and silicon dioxide particles in the second dispersion were 8.6 mass% and 2.9 mass%, respectively. The second dispersion was applied to one side of a colored fabric, followed by drying and baking to form an intermediate layer.

[0083] <Formation of adhesive layer> A peroxide-curing silicone adhesive was used as the adhesive, and benzoyl peroxide was used as the curing agent. The adhesive and curing agent were dissolved in xylene as a solvent to prepare an adhesive-containing solution. This solution contained 50% by weight of the adhesive and 1% by weight of the curing agent based on the weight of the solution.

[0084] This solution was applied to the intermediate layer to form a coating film. The laminate with the coating film formed on the intermediate layer was placed in an electric oven and subjected to heat treatment while left stationary. This heat treatment was carried out at a temperature of 200°C for 280 seconds. In this way, the pressure-sensitive adhesive tape of Example 1 was produced. In the produced pressure-sensitive adhesive tape, the thickness of the colored fabric was about 65 μm, the thickness of the intermediate layer was about 1 μm, and the thickness of the pressure-sensitive adhesive layer was about 50 μm.

[0085] Examples 2 to 4 In Examples 2 to 4, adhesive tapes were produced in the same manner as in Example 1, except that the number of times of impregnation coating was changed when producing the colored fabric.

[0086] <Color evaluation of colored fabric surfaces> The color tone of the surface of the colored fabric provided on the adhesive tape prepared in each example was measured using a spectrophotometer CM-5 and a color difference meter CR-5 manufactured by KONICA MINOLTA. * a * b * The measurement was carried out using a color system. During the measurement, the L * , a* and b * The results are shown in Table 1 below.

[0087] <Mass measurement> For the pressure-sensitive adhesive tapes produced in each example, the mass per unit area of ​​the colored fabric M1, the mass per unit area of ​​the colored fluororesin layer M2, and the mass per unit area of ​​the inorganic pigment contained in the colored fluororesin layer M3 were measured by the methods described above. These results are shown in Table 1 below.

[0088] [Table 1]

[0089] In the pressure-sensitive adhesive tapes according to Examples 1 to 4, the color tone of the surface of the colored fabric was a good orange color. 2 ~70.0g / m 2 In Examples 1 and 3, which are within the range of * a shows a reddish hue while suppressing it from exceeding 50.0 * The colored fabrics according to Examples 1 and 3 exhibited particularly excellent orange color development.

[0090] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations where possible, and in such cases, the combined effects can be obtained. Furthermore, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining the disclosed multiple constituent elements. For example, if some constituent elements are deleted from all constituent elements shown in the embodiments, and the problem stated in the "Problem to be Solved by the Invention" section can be solved and the effect stated in the "Effect of the Invention" section can be obtained, the configuration from which these constituent elements are deleted can be extracted as an invention. [Explanation of symbols]

[0091] 1...colored fabric, 2...glass cloth, 3...colored fluororesin layer, 4...intermediate layer, 5...adhesive layer.

Claims

1. Colored fabrics and an intermediate layer laminated on one side of the colored fabric and containing silicon dioxide particles; a pressure-sensitive adhesive layer laminated on the intermediate layer, The colored fabric is an adhesive tape comprising a glass cloth and a colored fluororesin layer formed on both sides of the glass cloth and containing a fluororesin and an inorganic pigment.

2. 2. The adhesive tape according to claim 1, wherein the inorganic pigment is a composite oxide containing tin, titanium, tungsten, and zinc.

3. The pressure-sensitive adhesive tape according to claim 1 or 2, wherein the fluororesin is at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylenepropene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer (ETFE).

4. For the colored fluororesin layer, the mass M2 of the fluororesin and the inorganic pigment per unit area is 25.0 g / m 2 ~90.0g / m 2 The pressure-sensitive adhesive tape according to any one of claims 1 to 3, wherein the thickness of the adhesive tape is within the range of

5. The mass M3 per unit area of ​​the inorganic pigment contained in the colored fluororesin layer is 1.0 g / m 2 ~5.0g / m 2 The adhesive tape according to any one of claims 1 to 4, wherein the thickness of the adhesive tape is within the range of

6. 6. The pressure-sensitive adhesive tape according to claim 1, wherein, in the colored fluororesin layer, a ratio M3 / M2 of a mass M3 per unit area of ​​the inorganic pigment to a mass M2 per unit area of ​​the fluororesin and the inorganic pigment is in a range of 0.03 to 0.

10.

7. The surface color of the colored fabric is L ＊ a ＊ b ＊ When expressed in the color system, L ＊ is in the range of 59.0 to 62.0, and a ＊ is in the range of 18.0 to 27.0, and b ＊ The pressure-sensitive adhesive tape according to any one of claims 1 to 6, wherein the viscosity is in the range of 25.0 to 55.

0.

8. 8. The adhesive tape according to claim 1, wherein the colored fabric has a thickness in the range of 50 μm to 300 μm.

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