Method for measuring mass of base material of tape-shaped prepreg or reinforcing fiber bundle base material, and method for producing tape-shaped prepreg base material

Abstract

Provided is a method for the highly accurate detection of the mass of the base material of a tape-shaped prepreg base material. In a method for measuring the mass of the base material of a tape-shaped prepreg base material, the method comprising causing a radiation device having a radiation source and a radiation detector to traverse a tape-shaped prepreg base material, which comprises reinforcing fiber and matrix resin and which has a width of 1 to 20 mm, in the width direction of the base material and, at this time, applying radiation from the radiation source, so as to determine a radiation attenuation rate from the amount of radiation that has passed through the base material and is incident on the radiation detector, and to calculate the mass per unit area of the base material on the basis of the obtained radiation attenuation rate, a calculation method for determining the radiation attenuation rate Ns of the tape-shaped prepreg base material is the method for measuring a tape-shaped prepreg base material using summation of the area values of log Nt of the radiation attenuation rate Nt at each point t in the width direction (t = 1, 2, 3, ... n, where t is an integer value). Nt: the radiation attenuation rate at each point t when the radiation attenuation rate is measured at n points in the range from a = T1 to a = T2 where the width direction of the base material is the a direction Ns: the radiation attenuation rate (area value of the natural logarithm log Nt of Nt at each point t) A: operator (constant) n: a freely settable natural number

Description

Method for measuring base material mass of tape-shaped prepreg or reinforcing fiber bundle base material, and method for manufacturing tape-shaped prepreg base material

[0001] The present invention relates to a method for measuring the mass of a substrate, i.e., the basis weight, of a tape-shaped prepreg or reinforcing fiber bundle substrate.

[0002] Fiber-reinforced composite materials (FRPs), in which matrix resins including thermoplastic resins and thermosetting resins are reinforced with reinforcing fibers, are used in a variety of fields, including aerospace materials, automotive materials, industrial materials, pressure vessels, building materials, housings, medical applications, and sports applications. In particular, carbon fiber-reinforced composite materials (CFRPs) are widely used when high mechanical properties and light weight are required. On the other hand, glass fiber-reinforced composite materials (GFRPs) are used when cost is prioritized over mechanical properties and light weight.

[0003] FRP is primarily manufactured as components by impregnating reinforcing fiber bundles with a matrix resin to obtain an intermediate substrate, which is then laminated and molded, and further heat-cured if a thermosetting resin is used as the matrix resin. In recent years, the applications mentioned above have seen more complex folded three-dimensional shapes than simple planar structures. To conform to these three-dimensional shapes, high-speed lamination of narrow tape-shaped intermediate substrates rather than wide sheet-shaped FRP substrates has been attracting attention from the perspectives of efficiency and moldability.

[0004] For example, in the field of automotive materials, pressure vessels with metal or resin liners reinforced with fiber-reinforced composite materials are used for high-pressure tanks installed in natural gas vehicles and fuel cell vehicles. Pressure vessels are manufactured by winding a reinforcing fiber bundle and a tape-shaped intermediate substrate made of a thermosetting resin around the outer periphery of the liner, forming a molded body, and then heat-curing the body. This manufacturing method is called the filament winding method (FW method). Because the strength and mass of the molded body depend heavily on the amount of resin attached, technologies for monitoring and controlling the amount of resin attached to the reinforcing fiber tape have been proposed (Patent Documents 1 and 2).

[0005] Inspections using radiation sources are performed to measure the thickness of substrates or the mass per unit area of ​​coating films as materials to be measured. Transmission-type inspection devices using radiation are thickness measurement devices based on the principle that the amount of radiation transmitted varies depending on the thickness of the material to be measured. In a typical measurement method, radiation emitted from a radiation source passes through the material to be measured and is received by a radiation detector sensor. The energy received by the radiation detector sensor is converted into an electrical pulse, which is output to a monitor via a data transmitter. When the radiation passes through the material to be measured, the strength of the electrical pulse changes depending on the thickness of the material, allowing the thickness of the material to be measured.

[0006] When measuring the thickness of a material using radiation, the radiation emitted from the radiation source tends to spread, resulting in a wide detection range for the light-receiving sensor. Patent Documents 3, 4, and 5 disclose techniques for improving detection accuracy when measuring the thickness of a sheet-like material. In Patent Document 5, a mask is attached to the front of the sensor surface of the radiation detector to cover a portion of the surface, thereby improving detection accuracy. This allows the radiation detector to receive radiation over a narrower range than the light-receiving sensor surface, thereby reducing the measurement area of ​​the material per unit time, thereby enabling sensitive measurement of the thickness of the material even if the thickness varies over a narrow range.

[0007] Japanese Patent No. 6579092 Japanese Patent No. 7002484 Japanese Patent Application Laid-Open No. 2007-298387 Japanese Patent Application Laid-Open No. 2007-51978 Japanese Patent Application Laid-Open No. 2002-296021

[0008] Inspection of FRP using a radiation source is based on the premise that the sheet is wide. If the width of the material being measured is narrow, the radiation receiving sensor of the radiation detector will receive not only the radiation that has passed through the material being measured, but also the radiation that has not passed through the material being measured, making the sensor's output pulse insensitive and unable to meet the demand for high measurement accuracy.

[0009] That is, when measuring a narrow tape-shaped substrate or a reinforcing fiber bundle substrate, measurement accuracy decreases due to diffraction of radiation occurring at the edges of the substrate, and if external disturbances such as the application of tension occur during measurement, the width and thickness of the substrate fluctuate. Therefore, detection accuracy varies greatly depending on the method of calculating the electrical signal incident on the light-receiving sensor of the radiation detector and the detection method of the radiation detector.

[0010] The object of the present invention is to provide a method for inspecting a narrow tape-shaped prepreg substrate or a reinforcing fiber bundle substrate using radiation, which specifies a detection method and a calculation method, and detects at least one of the substrate mass, resin mass, and thickness with high accuracy based on the obtained radiation attenuation rate.

[0011] The inspection method of the present invention that solves the above problems is as follows: 1. A radiation device having a radiation source and a radiation detector is moved across a tape-shaped prepreg base material having a width of 1 to 20 mm, which contains reinforcing fibers and a matrix resin, in the width direction of the base material, and a radiation dose V ０ The radiation amount V that passes through the substrate and is incident on the radiation detector is calculated by Equation 2 and Equation 3. ０ and calculating the mass d per unit area of ​​the substrate based on the radiation attenuation rate Ns obtained, the method for calculating the radiation attenuation rate Ns of the tape-shaped prepreg substrate is the sum of the area values ​​of logNt of the radiation attenuation rate Nt at each point t (t=1, 2, 3, ... n: where t is an integer value) in the width direction based on Equation 1.

[0012]

[0013] u ｓ : Mass attenuation coefficient of tape-shaped prepreg base material d ｓ: substrate mass of tape-shaped prepreg substrate Nt: radiation attenuation rate at each point t when the substrate width direction is the a direction and the radiation attenuation rate is measured at n points in the range from a = T1 to a = T2 Ns: radiation attenuation rate (area value of the natural logarithm logNt of Nt at each point t) A: operator (constant) n: natural number that can be set arbitrarily 2. The method for measuring the substrate mass of a tape-shaped prepreg substrate according to 1, wherein (W1 x D2) / (W0 x D1) is greater than 0 and not more than 0.3, where W0 is the substrate width, W1 is the width of the radiation incident on the radiation detector, D1 is the distance from the light-emitting part of the radiation source to the light-receiving part of the radiation detector, and D2 is the distance from the light-emitting part of the radiation source to the substrate. 3. A method for measuring the base material mass of a tape-shaped prepreg base material according to 1 or 2, in which a tape-shaped prepreg base material having a width of 1 to 20 mm and a standard deviation of base material width over a longitudinal length of 3,000 m is to be measured is 0.1 mm or more. 4. A method for producing a tape-shaped prepreg base material, comprising the steps of: applying or impregnating reinforcing fibers with resin to obtain a tape-shaped prepreg base material; and determining the base material mass per unit length in the longitudinal direction or the resin mass per unit length in the longitudinal direction of said base material by the method for measuring the base material mass of a tape-shaped prepreg base material according to any of 1 to 3 above, wherein control is performed in the application or impregnation step to match the determined value of the item with a target value.

[0014] 5. A radiation device having a radiation source and a radiation detector is moved across the width of a reinforcing fiber bundle substrate having a width of 1 to 20 mm, and a radiation dose V is detected from the radiation source. ０ The radiation amount V that passes through the substrate and is incident on the radiation detector is calculated by Equations 5 and 6. ０ and calculating the mass d per unit area of ​​the substrate based on the radiation attenuation rate Nb obtained, the method for calculating the radiation attenuation rate Nb of the reinforcing fiber bundle substrate is the sum of the area values ​​of logNt of the radiation attenuation rate Nt at each point t (t=1, 2, 3, ... n: where t is an integer value) in the width direction based on Equation 4.

[0015]

[0016] u ｂ : Mass attenuation coefficient of reinforcing fiber bundle substrate d ｂ : substrate mass of the reinforcing fiber bundle Nt: radiation attenuation rate at each point t when the substrate width direction is the a direction and the radiation attenuation rate is measured at n points in the range from a = T1 to a = T2 Nb: radiation attenuation rate (area value of the natural logarithm logNt of Nt at each point t) A: operator (constant) n: any natural number that can be set 6. The method for measuring the substrate mass of a reinforcing fiber bundle according to 5, wherein, when the substrate width is W0, the width of the radiation incident on the radiation detector is W1, the distance from the light-emitting part of the radiation source to the light-receiving part of the radiation detector is D1, and the distance from the light-emitting part of the radiation source to the substrate is D2, (W1 × D2) / (W0 × D1) is greater than 0 and not more than 0.3. 7. The method for measuring the substrate mass of a reinforcing fiber bundle according to 5 or 6, wherein the measurement target is a reinforcing fiber bundle substrate having a width of 1 to 20 mm and having a standard deviation of the substrate width over a longitudinal length of 3,000 m of 0.1 mm or more. 5. A method for producing a tape-like prepreg base material according to claim 4, comprising a step of determining the resin mass by subtracting the substrate mass of the reinforcing fiber bundle obtained by the method for measuring the substrate mass of a reinforcing fiber bundle according to any one of claims 5 to 7 from the substrate mass of the tape-like prepreg base material obtained by the method for measuring the substrate mass of a tape-like prepreg base material according to any one of claims 1 to 3, and controlling the resin mass to coincide with a target value.

[0017] According to the narrow substrate inspection method of the present invention, by specifying the detection method and calculation method, it is possible to detect at least one of the substrate mass, resin mass, and thickness with high accuracy based on the obtained radiation attenuation rate, thereby stabilizing the quality of the product.

[0018] 1 is a top view and a side cross-sectional view showing the configuration of a transmission type inspection device according to one embodiment of the present invention; 2 is a side cross-sectional view of a measurement device when measuring a wide sheet, and a diagram showing the transition of the radiation attenuation rate obtained when the thickness and mass are measured by a measurement method according to the prior art; 3 is a side cross-sectional view of a measurement device when measuring a tape-shaped prepreg base material, and a diagram showing the transition of the radiation attenuation rate obtained when the thickness and mass are measured by a measurement method according to the prior art; 4 is a side cross-sectional view of a measurement device when measuring a tape-shaped prepreg base material, and a diagram showing the transition of the radiation attenuation rate obtained when the thickness and mass are measured by a measurement method according to the prior art; 5 is a side cross-sectional view of a measurement device when measuring a tape-shaped prepreg base material using the measurement method of the present invention, and an example of a method for calculating the radiation attenuation rate; 6 is a side cross-sectional view showing a state in which a cover that covers a part of the radiation receiving part of the radiation detector is attached to measure the base material mass of the tape-shaped prepreg base material;

[0019] A preferred embodiment of the present invention will be described with reference to the drawings. Note that the following description is merely an example of an embodiment of the present invention, and the present invention should not be construed as being limited thereto. Various modifications are possible within the scope of the objects and effects of the present invention.

[0020] <Outline of Measurement Method> First, an outline of the present invention will be described using an example of a method for measuring the substrate mass of a tape-shaped prepreg substrate (hereinafter sometimes referred to as a tape-shaped substrate) with reference to Figures 1 and 2. In the present invention, the tape-shaped substrate contains reinforcing fibers and a matrix resin, and more specifically, a prepreg formed by impregnating reinforcing fibers with a matrix resin takes on a tape-like shape. Furthermore, in the present invention, the reinforcing fiber bundle substrate is a bundle of reinforcing fibers, and can be made into a tape-shaped substrate by impregnating the reinforcing fiber bundle substrate with a matrix resin.

[0021] 1 is a diagram showing the configuration of a radiation transmission type inspection device for measuring the substrate mass of a tape-shaped substrate according to one embodiment of the present invention. The radiation device X is a transmission type measurement device that measures the substrate mass of a tape-shaped prepreg substrate, or simply a tape-shaped substrate Y, by detecting the amount of attenuation in the intensity of radiation that passes through the tape-shaped substrate Y, and is equipped with a radiation source 2, a radiation detector 3, and a support frame 1 (an example of an equipment moving means) equipped with a drive unit that supports the radiation source 2 and the radiation detector 3 so that they can move in the width direction of the tape-shaped substrate Y. The radiation source 2 and the radiation detector 3 that constitute the radiation device X can be installed opposite each other with the tape-shaped substrate Y in between, and can be maintained in this opposing state by the support frame 1 equipped with the drive unit.

[0022] 2, from the viewpoint of process efficiency, it is preferable to use a method for measuring and inspecting the substrate masses of a plurality of tape-shaped substrates Y arranged in parallel using a single radiation device X. In the present invention, the tape-shaped substrate Y may or may not run in its longitudinal direction (length direction).

[0023] Next, the measurement operation of the measuring device configured as described above will be described. When an instruction to start measurement of the tape-shaped substrate Y is given, the radiation device X is driven in the width direction perpendicular to the longitudinal direction of the tape-shaped substrate Y. This movement of the radiation device X is referred to as "traverse" in the present invention, and may or may not involve the use of a driving force. As a result, the radiation device X traverses the width direction of the tape-shaped substrate Y, and the substrate mass of the tape-shaped substrate Y is measured. When the tape-shaped substrate Y is running in its longitudinal direction, the substrate mass of the tape-shaped substrate Y can also be measured continuously in the longitudinal direction by traversing the radiation device X as a reciprocating motion that repeatedly traverses the substrate in the width direction. The radiation to be irradiated is not particularly limited, and β rays, X-rays, or γ rays can be selected depending on the thickness and raw material of the substrate to be measured.

[0024] <Method for calculating the radiation attenuation rate of a tape-shaped substrate> In the method for measuring the substrate mass of the present invention, a radiation source 2 and a radiation detector 3 are arranged to face each other. ０The radiation enters the surface of the tape-shaped substrate Y facing the radiation source, passes through the substrate, exits from the other surface, and reaches the radiation detector 3. At this time, the radiation emitted from the radiation source 2 attenuates as it passes through the air and the tape-shaped substrate Y (see FIG. 5). Using the attenuated radiation dose V detected by the light-receiving unit 4 of the radiation detector 3, the substrate mass d of the tape-shaped substrate or reinforcing fiber substrate is measured based on a predetermined calculation formula. Generally, when the sheet-shaped substrate YS shown in FIGS. 3 and 5 is the object to be measured, the radiation dose V detected by the radiation detector is calculated as the radiation dose V detected by the radiation detector shown in Equation 7, and the radiation attenuation rate N is measured at each position in the substrate width direction, and log N (N is the natural logarithm) is calculated as shown in the graph in FIG. 3. From the calculated log N, the substrate mass d at each position is calculated according to Equation 8. Here, the attenuation coefficient u of the substrate is a constant determined by the material and resin type. The radiation dose attenuation rate, or transmittance, is proportional to the thickness [m]. Mass [kg] is the density [kg / cm ３ ] can be converted to mass per unit area, and as a result, the attenuation rate of the radiation dose is proportional to the mass.

[0025]

[0026] V: Radiation dose detected by the radiation detector V ０ : Radiation dose emitted from the radiation source N: Radiation attenuation rate at each position in the width direction of the substrate (= V / V ０ ) u: mass attenuation coefficient d: substrate mass However, when a tape-shaped substrate or reinforcing fiber substrate having a width of 1 to 20 mm is irradiated with radiation from the radiation source while being traversed in the width direction of the substrate by a radiation device X having a radiation source 2 and a radiation detector 3, and the radiation attenuation rate is calculated from the amount of radiation that has passed through the substrate and is incident on the radiation detector, the substrate width and thickness vary, and the radiation amount detected will include areas where a tape-shaped substrate Y is present and areas where it is not. As shown in Figure 4, the log N obtained by traversing multiple tape-shaped substrates Y arranged in parallel in the width direction of the substrate means that radiation that has not passed through the material to be measured (which is less likely to attenuate) is also received by the photosensor of the radiation detector at the same time, which reduces the measurement accuracy of the substrate mass.

[0027] Furthermore, when measuring a narrow tape-shaped substrate or a reinforcing fiber bundle substrate, diffraction of radiation occurring at the edges of the substrate makes it difficult for radiation attenuation to occur. Furthermore, if there is a disturbance such as the application of tension during measurement, the substrate width will fluctuate, further fluctuating the electrical signal based on the amount of radiation incident on the light receiving sensor of the radiation detector.

[0028] Therefore, in the present invention, the mass per unit length in the longitudinal direction of a tape-shaped substrate or a reinforcing fiber substrate is calculated based on the area value of the radiation attenuation rate obtained using Equation 1. That is, as shown in FIG. 6, the radiation attenuation rate Nt is determined at each point t across a range including the width direction of the substrate, and then the area value Ns is calculated using Equation 1. The value of Ns is then substituted for log N in Equation 8 to determine the substrate mass d. This reduces the influence of diffraction of the radiation source occurring at the substrate edge, and even if the substrate width or thickness fluctuates due to external disturbances such as tension application during measurement, the calculation is performed over the entire substrate width, enabling highly accurate measurements. In FIG. 6, the horizontal axis represents the substrate width direction, and the vertical axis represents the log N of the radiation attenuation rate N. The area value Ns (shaded area in FIG. 6) obtained using Equation 1 is the sum of the area values ​​of log Nt at each of n points in the substrate width direction T1 to T2. Note that FIG. 6 also shows measured values ​​obtained using a conventional method as an example, with dotted lines.

[0029] In order to reduce the effect of diffraction of radiation occurring at the edge of the substrate and increase the number of measurement points not affected by diffraction, it is preferable that n in formula 1 is as large as possible, and it is most preferably equal to or greater than 30. A preferred upper limit of n is 50, although this depends on the substrate width, and even if n is increased beyond 50, a greater effect is often not obtained.

[0030] Furthermore, the use of the calculation formula of the present invention is most effective when the measurement range is equal to or greater than the width of the substrate, and it is preferable that the difference between T1 and T2 (T1-T2) showing the measurement range in Figure 6 is equal to or greater than the width of the substrate.

[0031]

[0032] Nt: radiation attenuation rate at each point t when measuring the radiation attenuation rate at n points in the range from a = T1 to a = T2, with the substrate width direction as the a direction Ns: radiation attenuation rate (area value of the natural logarithm logNt of Nt at each point t) A: operator (constant) n: a natural number that can be set arbitrarily The area value is calculated using Formula 1, and is obtained by multiplying the total value of logNt, which is the natural logarithm of the radiation attenuation rate Nt at each of t = 1 to n, by the operator A. Furthermore, when measuring the radiation attenuation rate Nt at n points in the range from a = T1 to a = T2, if the coordinates of each point in the substrate width direction a are α, it is preferable to determine α based on Formula 9, which has a term obtained by dividing (T1-T2) indicating the analysis range at equal intervals.

[0033]

[0034] Furthermore, to reduce the effects of diffraction, it is preferable that the width of the radiation incident on the light-receiving unit 4 of the radiation detector 3 is small. Referring to Figure 7, if the substrate width of the tape-shaped substrate Y is W0, the width of the radiation incident on the light-receiving unit 4 of the radiation detector 3 is W1, D1 is the distance from the light-emitting unit of the radiation source to the light-receiving unit of the radiation detector, and D2 is the distance from the light-emitting unit of the radiation source to the substrate, then (W1 x D2) / (W0 x D1) is preferably greater than 0 but not greater than 0.3. Here, each of the above distances represents the shortest distance. More preferably, (W1 x D2) / (W0 x D1) is 0.05 or less, and particularly preferably 0.03 or less. In this case, (W1 x D2) / (W0 x D1) may be adjusted by covering part of the front surface of the radiation-receiving unit 4 of the detector 3 with a cover 5, as shown in Figure 7, so that radiation can pass only through a slit-shaped opening extending in the width direction of the substrate, thereby reducing W1. Specifically, a cover 5 that covers a part of the detector 3 is attached to the detector 3 .

[0035] <Reinforcing Fiber> Examples of reinforcing fibers used in the present invention include carbon fibers, glass fibers, metal fibers, metal oxide fibers, metal nitride fibers, organic fibers (aramid fibers, polybenzoxazole fibers, polyvinyl alcohol fibers, polyethylene fibers, etc.), etc. From the viewpoint of the mechanical properties and light weight of the FRP, it is preferable to use carbon fibers.

[0036] <Matrix Resin> The matrix resin contained in the tape-shaped substrate used in the present invention can be selected appropriately depending on the application, and can be any resin commonly used in FRP, such as a thermoplastic resin, a thermosetting resin, or a photocurable resin. It can also be used as a resin composition containing particles, a curing agent, and various additives, as needed. The matrix resin can be a molten resin obtained by heating and melting it, or a matrix resin that is liquid at room temperature. It can also be a solution or varnish prepared using a solvent.

[0037] <Tape-shaped prepreg substrate> Examples of prepreg substrates include unidirectional materials (hereinafter referred to as UD substrates) in which multiple reinforcing fibers are aligned in one direction on a surface, and substrates in which a reinforcing fiber fabric in which reinforcing fibers are aligned multiaxially or randomly is impregnated with a matrix resin. Known methods can be used to form UD substrates, and there are no particular limitations. However, from the perspective of process efficiency and uniformity of alignment, a preferred method is to form a reinforcing fiber bundle in which single fibers are pre-aligned, then align these reinforcing fiber bundles to form a reinforcing fiber tape, and then impregnate the reinforcing fiber tape with a matrix resin. For example, prepreg substrates using carbon fiber as the reinforcing fiber are often formed by winding a "tow," which is a tape-shaped reinforcing fiber bundle, around a bobbin. However, a tape-shaped substrate with a width ranging from 1 to 20 mm can also be obtained by impregnating a single-filament tape-shaped reinforcing fiber bundle drawn from the bobbin with a matrix resin. Alternatively, a reinforcing fiber tape having multiple reinforcing fiber bundles arranged in a filamentary pattern can be impregnated with a matrix resin to obtain a tape-like substrate having a width exceeding 20 mm, which can then be slit in the width direction to obtain a tape-like substrate having a width in the range of 1 to 20 mm.

[0038] Not only for tape-shaped substrates, but also for reinforcing fiber substrates, it is preferable to set the width of the substrate in the range of 8 to 12 mm, as this significantly demonstrates the effects of the measurement method of the present invention. Even if the width of the substrate shows a certain standard deviation in a certain longitudinal length, if the width of the portion to be measured is 1 to 20 mm, it can be said that the substrate has a width in the range of 1 to 20 mm.

[0039] Furthermore, the measurement method of the present invention enables high-precision measurements even when the substrate width of a tape-shaped substrate or reinforcing fiber substrate varies. Therefore, it is suitable for use when measuring substrates whose standard deviation of substrate width over a longitudinal length of 3000 m is 0.1 mm or more. When the standard deviation over a 2000 m length is 0.1 mm or more, the effects of the present invention may be more clearly demonstrated compared to conventional methods, and when the standard deviation over a 1000 m length is 0.1 mm or more, the effects may be even more pronounced. While there is no upper limit to the standard deviation of the substrate width that can be measured, a range of 2.0 mm or less is typically preferred. The effects of the present invention are greater, and therefore more favorable, as the substrate width varies more. The standard deviation is determined by measuring the width at 50 or more points at intervals of at least one point per meter along the longitudinal length of the tape-shaped substrate or reinforcing fiber substrate (e.g., the substrate width every 0.017 m).

[0040] <Method for manufacturing tape-shaped prepreg substrate> Using a UD substrate as an example, Figure 8 shows an outline of one embodiment of a method for manufacturing a tape-shaped substrate Y using the measurement method of the present invention. The manufacturing apparatus used in this manufacturing method includes a resin application device 90 for applying resin R to one or both sides of one or more reinforcing fibers paid out from a payout device, a radiation device X for measuring the substrate mass per unit length in the longitudinal direction of the tape-shaped substrate Y or the resin mass per unit length in the longitudinal direction after resin application, a take-up unit 80, and a winding device. The resin mass per unit length in the longitudinal direction can be calculated by subtracting the reinforcing fiber substrate mass per unit length in the longitudinal direction from the tape-shaped substrate mass per unit length in the longitudinal direction.

[0041] That is, the mass of the resin can be determined by subtracting the mass of the substrate only, u, obtained from log Nb, based on the radiation attenuation rate Nb of the reinforcing fiber bundle substrate, from the substrate mass, u, obtained from log Ns, based on the radiation attenuation rate Ns of the tape-shaped prepreg substrate containing reinforcing fibers and a matrix resin. In this case, the calculation method for determining the radiation attenuation rate Ns of the tape-shaped prepreg substrate containing reinforcing fibers and a matrix resin is the sum of the area values ​​of log Nt of the radiation attenuation rate Nt at each point t in the width direction (t = 1, 2, 3, ... n: where t is an integer value) based on Equation 1. Furthermore, the calculation method for determining the radiation attenuation rate Nb of the reinforcing fiber bundle substrate is the sum of the area values ​​of log Nt of the radiation attenuation rate Nt at each point t in the width direction (t = 1, 2, 3, ... n: where t is an integer value) based on Equation 4.

[0042] In the resin R application process 90, a resin reservoir tank 92 is equipped with the resin R and a resin application roll 91, and the resin R is stored in the resin reservoir tank 92. The application roll 91 rotates to apply the resin R to one side of the reinforcing fibers, and the amount of resin R applied to the reinforcing fibers is adjusted by changing its rotation speed. Therefore, if the values ​​of the evaluation items, such as the substrate mass per unit length in the longitudinal direction of the tape-shaped substrate Y after resin application or the resin mass per unit length in the longitudinal direction, measured by the radiation device X, deviate from the predetermined target values, the rotation speed of the resin application roll 91 can be changed, for example, to stably produce a tape-shaped substrate Y having a predetermined substrate mass. The take-up unit 80 includes a nip roll 81 and a drive roll 82 and functions to feed the tape-shaped substrate Y to the take-up unit. The upper and lower limits of the numerical ranges described above can be combined arbitrarily.

[0043] <Confirmation of detection accuracy using tape-shaped prepreg base material> The present invention will be described in more detail below using examples, but the present invention is not necessarily limited to these examples. As examples, the improvement of measurement accuracy using the method for measuring the base material mass of a tape-shaped base material of the present invention was evaluated.

[0044] <Tape-shaped prepreg substrate> As a tape-shaped prepreg substrate for measuring detection accuracy, a bundle of unidirectionally aligned carbon fibers ("Torayca (registered trademark)" T900S (36K) single strand) was impregnated with a composition containing a thermosetting epoxy resin. The amount of the composition applied was varied to create seven towpreg levels, all of which were approximately 10 mm wide but had different masses per unit length in the longitudinal direction. The towpreg samples were cut into 1-meter lengths and measured on a scale. The masses per unit length in the longitudinal direction were (1) 2.21, (2) 2.15, (3) 2.12, (4) 2.10, (5) 2.07, (6) 2.05, and (7) 2.02 g / m for each level. The standard deviation calculated by measuring the towpreg width every 0.017 m over a 700-m length of the towpreg during production was 0.37 mm.

[0045] <Confirmation of Detection Accuracy> The detection accuracy of the cut towpreg was evaluated using an X-ray thickness gauge (SX-1100) manufactured by NanoGray Co., Ltd. The tube voltage, tube current, and irradiation size of the X-ray source unit were 8 kV, 30 uA, and approximately 7.5 mm in diameter, respectively. The radiation source 2 and the radiation receiving unit 4 of the radiation detector 3 were positioned facing each other across the towpreg to be measured, and measurements were taken by moving them in the same direction across the width of the towpreg at the same speed of 15 mm / sec. The distance from the light-emitting unit of the radiation source 2 to the light-receiving unit 4 of the radiation detector 3 was defined as D1, and the distance from the light-emitting unit of the radiation source 2 to the towpreg was defined as D2, so that D1 / D2 = 2 (the same was true for the confirmation of detection accuracy using a reinforcing fiber bundle substrate, described below).

[0046] <Examples 1 to 4, Comparative Examples 1 to 4> Using a method according to the prior art, radiation was detected by the radiation detector 3 at one point in the width direction of the substrate. As illustrated in Figure 4, the radiation attenuation rate log N was found, and the results of calculating the substrate mass d are shown in Comparative Examples 1 to 4 in Table 1. The results of calculating the substrate mass d based on Equations 1 to 3 of the present invention are shown in Examples 1 to 4 in Table 1.

[0047] In Comparative Examples 2 to 4 and Examples 2 to 4, a metal cover 5 was attached to cover part of the front surface of the radiation receiving unit 4, allowing radiation to pass only through a slit-shaped opening extending in the width direction of the substrate, thereby reducing (W1×D2) / (W0×D1) compared to Example 1 and Comparative Example 1. (The same was applied to the confirmation of detection accuracy using a reinforcing fiber bundle substrate, described below.) In Table 1, the length of the slit-shaped opening in the width direction of the substrate (i.e., W1) multiplied by the length in the longitudinal direction of the substrate is shown as "slit."

[0048] Detection accuracy was evaluated based on the coefficient of determination (R2) of the mass per unit length in the length direction of a cut towpreg (7 levels) measured on a scale and the measured value obtained using a radiation device. The coefficient of determination (R2) is an index that expresses correlation and indicates the degree to which predictions made by a regression model fit actual data. It is usually expressed as a value between 0 and 1, and the larger the R2, the stronger the correlation, indicating that the results of the calculation model match the actual data.

[0049] Comparing Comparative Example 1 with Example 1 in Table 1, it can be seen that by using the measurement method of the present invention, the coefficient of determination R2 is increased to 0.935, improving measurement accuracy, compared to when the method of the prior art is used. Also, comparing Examples 1 to 4, it can be seen that when a cover that covers part of the front surface of the X-ray detector is attached so that radiation can pass only through a slit-shaped opening extending in the width direction of the substrate, the coefficient of determination R2 increases to 0.95 or more, and that by making (W1 × D2) / (W0 × D1) smaller, the coefficient of determination R2 further increases, improving measurement accuracy.

[0050]

[0051] <Confirmation of detection accuracy using reinforcing fiber bundle substrate> <Reinforcing fiber bundle substrate> As the reinforcing fiber bundle substrate for measuring the detection accuracy, carbon fiber ("TORAYCA (registered trademark)" T800S (24K), T1100G (12K), T700G (12K), M40S (12K)) (Levels (8) to (11)) and Toray Industries, Inc. carbon fiber (24K) (Level (12)) were used. The mass per unit length in the longitudinal direction of the carbon fiber was measured by cutting it into 1 m units in the longitudinal direction and measuring it on a balance, and was (8) 1.043, (9) 0.502, (10) 0.825, (11) 0.501 g / m, and (12) 1.563, respectively.

[0052] <Confirmation of detection accuracy> The detection accuracy of the cut carbon fiber was evaluated using an X-ray thickness gauge (SX-1100) manufactured by NanoGray Co., Ltd. The tube voltage, tube current, and irradiation size of the X-ray source unit were set to 16 kV, 30 uA, and approximately 7.5 mm in diameter, respectively, and the radiation source 2 and the radiation receiving part 4 of the radiation detector 3 were placed facing each other with the carbon fiber to be measured therebetween, and measurements were taken by moving the radiation source 2 and the radiation receiving part 4 of the radiation detector 3 in the width direction of the carbon fiber at the same speed of 20 mm / sec.

[0053] Example 5, Comparative Example 5 Using a conventional method, radiation was detected at one point in the width direction of the substrate using a radiation detector. As shown in Figure 4, the radiation attenuation rate log N was determined, and the substrate mass d was calculated. The results are shown in Comparative Example 5 of Table 2. The substrate mass d was calculated based on Equations 4 to 6 of the present invention, and the results are shown in Example 5 of Table 2.

[0054] The detection accuracy was evaluated based on the mass per unit length in the longitudinal direction of the cut carbon fiber measured on a scale, as shown above, and the coefficient of determination R2 of the measured value obtained by the method using the radiation device. Comparing Comparative Example 5 and Example 5 in Table 2, it can be seen that by using the measurement method of the present invention, the coefficient of determination R2 was increased to 0.996 compared to when the method of the prior art was used, and measurement accuracy was improved.

[0055]

[0056] REFERENCE SIGNS LIST 1 Support frame equipped with a drive unit that supports the radiation device so that it can move in the width direction 2 Radiation source 3 Radiation detector 4 Radiation receiving unit 5 Cover X Radiation device Y Tape-shaped substrate YS Sheet-shaped substrate R Resin 80 Take-up unit 81 Nip roll 82 Drive roll 90 Resin application device 91 Resin application roll 92 Resin reservoir tank 101 Transport roll

Claims

1. For a tape-shaped prepreg base material having a width of 1 to 20 mm and containing reinforcing fibers and a matrix resin, while traversing a radiation device having a radiation source and a radiation detector in the width direction of the base material, the radiation dose V ０ is irradiated, and from the radiation dose V incident on the radiation detector that has passed through the base material, the radiation attenuation rate N, which is the ratio of V to V ０ in accordance with Formula 2 and Formula 3, is obtained, and based on the obtained radiation attenuation rate N, the mass d per unit area of the base material is calculated. In the method for measuring the base material mass of a tape-shaped prepreg base material, the calculation method for obtaining the radiation attenuation rate Ns of the tape-shaped prepreg base material is the sum of the area values of log Nt of the radiation attenuation rates Nt at each point t (t = 1, 2, 3,..., n: where t is an integer value) in the width direction based on Formula 1. A method for measuring the base material mass of a tape-shaped prepreg base material. u ｓ : Mass attenuation coefficient of the tape-shaped prepreg base material d ｓ : Base material mass of the tape-shaped prepreg base material Nt: The base material width direction is defined as the a direction. When measuring the radiation attenuation rates at n points in the range from a = T1 to a = T2, the radiation attenuation rate at each point t Ns: Radiation attenuation rate (area value of the natural logarithm log Nt of Nt at each point t) A: Operator (constant) n: Arbitrarily set natural number 2. When the width of the base material web is W0 and the width of the radiation incident on the radiation detector is W1, and the distance from the light-emitting part of the radiation source to the light-receiving part of the radiation detector is D1 and the distance from the light-emitting part of the radiation source to the base material is D2, the method for measuring the base material mass of the tape-shaped prepreg base material according to claim 1, wherein (W1 × D2) / (W0 × D1) exceeds 0 and is 0.3 or less.

3. The method for measuring the base material mass of the tape-shaped prepreg base material according to claim 1 or 2, wherein the tape-shaped prepreg base material having a width of 1 to 20 mm and a standard deviation of the base material width of 0.1 mm or more over a longitudinal length of 3000 m is a measurement target.

4. A method for manufacturing a tape-shaped prepreg base material, comprising: a step of applying or impregnating a resin to reinforcing fibers to obtain a tape-shaped prepreg base material; and a step of determining the base material mass per unit length in the length direction or the resin mass per unit length in the length direction of the base material by the method for measuring the base material mass of the tape-shaped prepreg base material according to claim 1 or 2, and performing control to match the value of the determined item to a target value in the applying or impregnating step.

5. For a reinforcing fiber bundle base material with a width of 1 to 20 mm, while traversing a radiation device having a radiation source and a radiation detector in the width direction of the base material, radiation dose V is irradiated from the radiation source, and from the radiation dose V incident on the radiation detector that has passed through the base material, the radiation attenuation rate Nb, which is the ratio of V to V, is obtained according to Formula 5 and Formula 6, and the mass d per unit area of the base material is calculated based on the obtained radiation attenuation rate Nb. In the method for measuring the base material mass of a reinforcing fiber bundle, the calculation method for obtaining the radiation attenuation rate Nb of the reinforcing fiber bundle base material is the sum of the area values of log Nt of the radiation attenuation rate Nt at each point t (t = 1, 2, 3,..., n: where t is an integer value) in the width direction according to Formula 4. Method for measuring the base material mass of a reinforcing fiber bundle. ０ Irradiate it, and from the radiation dose V incident on the radiation detector that has passed through the base material, according to Formula 5 and Formula 6, obtain the radiation attenuation rate Nb, which is the ratio of V to V. ０ Based on the obtained radiation attenuation rate Nb, calculate the mass d per unit area of the base material. In the method for measuring the base material mass of a reinforcing fiber bundle, the calculation method for obtaining the radiation attenuation rate Nb of the reinforcing fiber bundle base material is the sum of the area values of log Nt of the radiation attenuation rate Nt at each point t (t = 1, 2, 3,..., n: where t is an integer value) in the width direction according to Formula 4. Method for measuring the base material mass of a reinforcing fiber bundle. u ｂ : Mass attenuation coefficient of the reinforcing fiber bundle base material d ｂ : Base material mass of the reinforcing fiber bundle Nt: Taking the base material width direction as the a direction, when measuring the radiation attenuation rate at n points in the range from a = T1 to a = T2, the radiation attenuation rate at each point t Nb: Radiation attenuation rate (area value of the natural logarithm log Nt of Nt at each point t) A: Operator (constant) n: Arbitrarily set natural number 6. When the width of the base material is W0 and the width of the radiation incident on the radiation detector is W1, and the distance from the light-emitting part of the radiation source to the light-receiving part of the radiation detector is D1 and the distance from the light-emitting part of the radiation source to the base material is D2, the method for measuring the base material mass of the reinforcing fiber bundle according to claim 5, wherein (W1 × D2) / (W0 × D1) exceeds 0 and is 0.3 or less.

7. The method for measuring the base material mass of the reinforcing fiber bundle according to claim 5 or 6, wherein the reinforcing fiber bundle having a width of 1 to 20 mm and a standard deviation of the base material width of 0.1 mm or more over a longitudinal length of 3000 m is a measurement target.

8. A method for manufacturing a tape-shaped prepreg base material according to claim 4, comprising a step of obtaining the resin mass by subtracting the base material mass of the reinforcing fiber bundle obtained by the method for measuring the base material mass of the reinforcing fiber bundle according to claim 5 or 6 from the base material mass of the tape-shaped prepreg base material obtained by the method for measuring the base material mass of the tape-shaped prepreg base material according to claim 1 or 2, and performing control to match the resin mass to a target value.

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