SMC Manufacturing Method

Abstract

Provided is an improvement in the manufacturing technology of CF-SMC, which includes a method for manufacturing SMC using a continuous carbon fiber bundle having nK single fibers that has been partially divided into n sub-bundles. The SMC manufacturing method of the present invention uses the following (A) fragmentation processing device to fragment the short-cut carbon fiber bundles deposited before the carrier film. (A) A fragmentation processing device comprising a first pin roller and a second pin roller, each having a rotation axis parallel to the rotation axis direction of the rotary cutter, wherein the first pin roller is driven to rotate so that the pin moves from top to bottom on the side facing the second pin roller, and the second pin roller is driven to rotate so that the pin moves from top to bottom on the side facing the first pin roller.

Description

Technical Field

[0001] The present invention relates to a method for producing SMC (sheet molding compound), and more particularly to a method for producing CF-SMC, which is SMC using carbon fiber (CF).

[0002] This application claims priority based on Japanese Patent Application No. 2020-047206, filed in Japan on March 18, 2020, the contents of which are incorporated herein by reference. Background Art

[0003] In recent years, CFRP (carbon fiber reinforced plastic), a composite material composed of carbon fiber and resin, has been widely used in parts for aircraft, automobiles, ships, and other transportation equipment, as well as sporting goods and leisure products. Some CFRP products are formed from CF-SMC using the compression molding method.

[0004] CF-SMC is a type of carbon fiber prepreg, and has a structure in which a mat composed of chopped carbon fiber bundles (also called "chopped carbon fiber tow" or "chopped carbon fiber strand") is impregnated with a thermosetting resin composition.

[0005] CFRP is reinforced with a carbon fiber bundle having a smaller number of single fibers, thereby increasing its strength. However, the smaller the number of single fibers in the carbon fiber bundle (the smaller the tow size), the higher the manufacturing cost (Patent Document 1).

[0006] There is a proposal to add a step of partially splitting the continuous carbon fiber bundle unwound from the creel before cutting it, to a method for producing SMC that continuously performs steps from cutting of the continuous carbon fiber bundle to resin impregnation of the carbon fiber layer (Patent Document 2).

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: U.S. Patent Application Publication No. 2012 / 0213997

[0010] Patent Document 2: International Publication No. 2017 / 221655 Summary of the Invention

[0011] Technical problem to be solved by the invention

[0012] Typically, it is thought that the use of a technique that partially splits continuous carbon fiber bundles containing a large number of single fibers, such as large tows, can be used to produce SMCs, which can produce high-strength CFRP molded products, at low cost. The process of partially splitting the continuous carbon fiber bundles requires various adjustments, so separating this process from subsequent steps in SMC production can potentially improve overall manufacturing efficiency.

[0013] The present invention was completed during the course of research conducted by the present inventors based on this idea, and its main object is to provide an improvement that is beneficial to the production technology of CF-SMC, including a method for producing CF-SMC by partially splitting a continuous carbon fiber bundle for use.

[0014] Technical problems that can be solved by various embodiments of the present invention may be disclosed explicitly or implicitly in this specification.

[0015] Means for solving technical problems

[0016] One embodiment of the present invention relates to a method for producing SMC. The SMC production method according to a preferred embodiment of the present invention is as follows, but is not limited thereto.

[0017] [1] A method for manufacturing a SMC, comprising:

[0018] (i) extracting from a package a continuous carbon fiber bundle having a single fiber number NK which has been partially divided into n sub-bundles in advance;

[0019] (ii) cutting the continuous carbon fiber bundle drawn out from the package into chopped carbon fiber bundles using a rotary cutter;

[0020] (iii) depositing the chopped carbon fiber bundles on a carrier film traveling below the rotary cutter to form a carbon fiber stack; and

[0021] (iv) impregnating the carbon fiber stack in a thermosetting resin composition;

[0022] The chopped carbon fiber bundle before being deposited on the carrier film is subjected to fragmentation treatment using the following (A) fragmentation treatment device,

[0023] (A) A first pin roller and a second pin roller each having a rotation axis parallel to the rotation axis direction of the rotary cutter are provided, the first pin roller is driven to rotate on the side facing the second pin roller so that the pin moves from top to bottom, and the second pin roller is driven to rotate on the side facing the first pin roller so that the pin moves from top to bottom.

[0024] [2] The manufacturing method according to [1], wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is greater than the distance between the rotation axes of the first pin roller and the second pin roller.

[0025] [3] The manufacturing method according to [2], wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is larger than the distance between the rotation axes of the first pin roller and the second pin roller.

[0026] [4] The manufacturing method as described in [1], wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is smaller than the distance between the rotation axes of the first pin roller and the second pin roller, and the difference between them is less than 10 mm.

[0027] [5] The production method according to any one of [1] to [4], wherein the continuous carbon fiber bundle is wound in the package so that there are no gaps between the sub-bundles.

[0028] [6] The production method according to any one of [1] to [5], wherein the continuous carbon fiber bundle is wound in the package so that adjacent sub-bundles overlap.

[0029] [7] The production method according to any one of [1] to [6], wherein, in the continuous carbon fiber bundle wound into the package, the total width is smaller than the sum of the widths of the sub-bundles.

[0030] [8] The production method according to any one of [1] to [7], wherein N is 15 or greater.

[0031] [9] The manufacturing method according to any one of [1] to [8], wherein the radius of the cylinder in each of the first pin roller and the second pin roller is greater than or equal to half of the maximum radius.

[0032]

[10] The manufacturing method according to any one of [1] to [9], wherein the peripheral speed of the pin tip of the first pin roller is equal to the peripheral speed of the pin tip of the second pin roller.

[0033]

[11] The manufacturing method according to any one of [1] to

[10] , wherein the content of carbon fiber bundles having a single fiber count exceeding 0.5K in the carbon fiber pile is 99% by weight or more.

[0034]

[12] A manufacturing method as described in any one of [1] to

[11] , wherein the number of chopped carbon fiber bundles with a single fiber number greater than {(N / n)+0.5}K contained in the unit weight of the carbon fiber stack is reduced by the fragmentation treatment.

[0035]

[13] The manufacturing method according to any one of [1] to

[12] , wherein the carbon fiber stack is pressurized together with the thermosetting resin composition in order to impregnate the carbon fiber stack in the thermosetting resin composition.

[0036]

[14] The manufacturing method according to any one of [1] to

[13] , wherein at least a portion of the thermosetting resin composition is applied to the upper surface of the carrier film before the step (iii).

[0037] Another aspect of the present invention relates to a method for treating a carbon fiber bundle. The method for treating a carbon fiber bundle according to a preferred embodiment of the present invention is as follows, but is not limited thereto.

[0038]

[15] A method for processing a carbon fiber bundle, comprising: performing a fragmentation treatment on a carbon fiber bundle having a fiber length of 60 mm or less using the following fragmentation treatment device (A):

[0039] (A) It is provided with a first pin roller and a second pin roller having mutually parallel rotation axes, the first pin roller is driven to rotate so that the pin moves from top to bottom on the side facing the second pin roller, and the second pin roller is driven to rotate so that the pin moves from top to bottom on the side facing the first pin roller.

[0040]

[16] The processing method as described in

[15] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is greater than the distance between the rotation axes of the first pin roller and the second pin roller.

[0041]

[17] The processing method as described in

[16] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is larger than the distance between the rotation axes of the first pin roller and the second pin roller.

[0042]

[18] The processing method as described in

[15] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is smaller than the distance between the rotation axes of the first pin roller and the second pin roller, and the difference between them is less than 10 mm.

[0043]

[19] The processing method according to any one of

[15] to

[18] , wherein the radius of the cylinder in each of the first pin roller and the second pin roller is more than half of the maximum radius.

[0044]

[20] The processing method as described in any one of

[15] to

[19] , wherein the peripheral speed of the pin front end of the first pin roller is equal to the peripheral speed of the pin front end of the second pin roller.

[0045] Still another aspect of the present invention relates to a carbon fiber bundle fragmentation processing apparatus. Preferred embodiments of the carbon fiber bundle fragmentation processing apparatus of the present invention are as follows, but are not limited thereto.

[0046]

[21] A fragmentation processing device for carbon fiber bundles, comprising a first pin roller and a second pin roller having rotating shafts parallel to each other, the first pin roller being capable of being driven to rotate on a side facing the second pin roller with the pin moving from top to bottom, and the second pin roller being capable of being driven to rotate on a side facing the first pin roller with the pin moving from top to bottom.

[0047]

[22] The fragmentation processing device as described in

[21] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is greater than the distance between the rotation axes of the first pin roller and the second pin roller.

[0048]

[23] The fragmentation processing device as described in

[22] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is larger than the distance between the rotation axes of the first pin roller and the second pin roller.

[0049]

[24] The fragmentation processing device as described in

[21] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is smaller than the distance between the rotation axes of the first pin roller and the second pin roller, and the difference between them is less than 10 mm.

[0050]

[25] The fragmentation processing device according to any one of

[21] to

[24] , wherein the radius of the cylinder in each of the first pin roller and the second pin roller is more than half of the maximum radius.

[0051] Still another aspect of the present invention relates to the use of a fragmentation processing device. The use of the fragmentation processing device according to a preferred embodiment of the present invention is as follows, but is not limited thereto.

[0052]

[26] A method for manufacturing SMC by using a fragmentation processing device, the method comprising: stacking chopped carbon fiber bundles on a carrier film to form a carbon fiber stack; and impregnating the carbon fiber stack in a thermosetting resin composition; and fragmenting the chopped carbon fiber bundles before being stacked on the carrier film using the following fragmentation processing device:

[0053] It is equipped with a first pin roller and a second pin roller having mutually parallel rotating axes. The first pin roller can be driven to rotate on the side facing the second pin roller so that the pin moves from top to bottom. The second pin roller can be driven to rotate on the side facing the first pin roller so that the pin moves from top to bottom.

[0054]

[27] The use as described in

[26] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is greater than the distance between the rotation axes of the first pin roller and the second pin roller.

[0055]

[28] The use as described in

[27] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is larger than the distance between the rotation axes of the first pin roller and the second pin roller.

[0056]

[29] The use as described in

[26] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is smaller than the distance between the rotation axes of the first pin roller and the second pin roller, and the difference between them is less than 10 mm.

[0057]

[30] The use according to any one of

[26] to

[29] , wherein the radius of the cylinder in each of the first pin roller and the second pin roller is more than half of the maximum radius.

[0058]

[31] A fragmentation processing device is used for the fragmentation processing of carbon fiber bundles with a fiber length of less than 60 mm. The fragmentation processing device comprises a first pin roller and a second pin roller having rotating shafts parallel to each other, and is capable of driving the first pin roller to rotate on a side facing the second pin roller with the pin moving from top to bottom, and is capable of driving the second pin roller to rotate on a side facing the first pin roller with the pin moving from top to bottom.

[0059]

[32] The use as described in

[31] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is greater than the distance between the rotation axes of the first pin roller and the second pin roller.

[0060]

[33] The use as described in

[32] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is larger than the distance between the rotation axes of the first pin roller and the second pin roller.

[0061]

[34] The use as described in

[31] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is smaller than the distance between the rotation axes of the first pin roller and the second pin roller, and the difference between them is less than 10 mm.

[0062]

[35] The use according to any one of

[31] to

[34] , wherein the radius of the cylinder in each of the first pin roller and the second pin roller is more than half of the maximum radius.

[0063] Effects of the Invention

[0064] According to the present invention, there is provided an improvement that is beneficial to the production technology of CF-SMC, including a method for producing SMC using a continuous carbon fiber bundle by partially dividing it. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is a schematic diagram of a fiber package manufacturing device.

[0066] Figure 2A This is a plan view of a continuous carbon fiber bundle immediately after being divided into five strands, as viewed from the thickness direction.

[0067] Figure 2B This is a cross-sectional view showing a cross section perpendicular to the fiber direction of a continuous carbon fiber bundle immediately after the bundle is partially divided into five strands.

[0068] Figure 3 This is a schematic diagram showing a cross section perpendicular to the fiber direction of a continuous carbon fiber bundle that has been partially divided into five strands and then wound around a bobbin.

[0069] Figure 4 It is a schematic diagram of the SMC manufacturing device.

[0070] Figure 5 is a schematic diagram of a rotary cutter.

[0071] Figure 6 is a schematic diagram of a fragmentation processing device.

[0072] Figure 7 This is a schematic diagram of a pin roller included in the fragmentation processing device.

[0073] Figure 8 A portion of the cylindrical circumference of a pin roller is shown in a planar unfolded view.

[0074] Figure 9 It is a schematic diagram showing the positional relationship and the like of two pin rollers included in the fragmentation processing device.

[0075] Figure 10 It is a bar graph showing the distribution of the number of single fibers in the chopped carbon fiber bundles in the carbon fiber layer.

[0076] Figure 11 It is a bar graph showing the distribution of the number of single fibers in the chopped carbon fiber bundles in the carbon fiber layer.

[0077] Figure 12 It is a bar graph showing the distribution of the number of single fibers in the chopped carbon fiber bundles in the carbon fiber layer.

[0078] Figure 13 It is a bar graph showing the distribution of the number of single fibers in the chopped carbon fiber bundles in the carbon fiber layer.

[0079] Figure 14This is a plan view of a continuous carbon fiber bundle immediately after being divided into five strands, as viewed from the thickness direction.

[0080] Figure 15 It is a bar graph showing the distribution of the number of single fibers in the chopped carbon fiber bundles in the carbon fiber layer. DETAILED DESCRIPTION

[0081] 1. Production Method of SMC SMC is a sheet-shaped carbon fiber prepreg obtained by impregnating a carbon fiber layer composed of chopped carbon fiber bundles in a curable resin composition.

[0082] One embodiment of the present invention is a method for producing an SMC including the following steps (i) to (iv).

[0083] (i) A step of unwinding a continuous carbon fiber bundle having NK number of single fibers, which has been partially divided into n sub-bundles in advance, from a package.

[0084] (ii) a step of cutting the continuous carbon fiber bundle unwound from the package into chopped carbon fiber bundles using a rotary cutter.

[0085] (iii) A step of depositing chopped carbon fiber bundles on a carrier film traveling below the rotary cutter to form a carbon fiber pile.

[0086] (iv) A step of impregnating the carbon fiber stack in a thermosetting resin composition.

[0087] In the SMC manufacturing method of this embodiment, a fragmentation process is performed by bringing at least a portion of the chopped carbon fiber bundles deposited in front of the carrier film into contact with a rotating body to fragment them. This fragmentation process results in a different single fiber number distribution of the chopped carbon fiber bundles included in the carbon fiber layer formed in step (iii) above than when this fragmentation process is not performed.

[0088] If necessary, a step of increasing the viscosity of the thermosetting resin composition may be further provided after the step (iv).

[0089] 1.1. Continuous carbon fiber bundles

[0090] In the SMC manufacturing method of this embodiment, a previously prepared package of a continuous carbon fiber bundle is used. The continuous carbon fiber bundle has NK single fibers and is partially divided into n sub-bundles.

[0091] NK means N x 1000. For example, a carbon fiber bundle consisting of 3000 single fibers has a single fiber count of 3K, while a carbon fiber bundle consisting of 12000 single fibers has a single fiber count of 12K.

[0092] N is usually 12 or more, preferably 15 or more, but is not limited thereto. For example, it may be 18, 24, 36, 48 or 50.

[0093] The continuous carbon fiber bundle is partially divided into n sub-bundles, in other words, a portion of the continuous carbon fiber bundle is divided into n equal parts. Each of the n fiber bundles formed by the n equal divisions is called a sub-bundle.

[0094] The package of the partially divided continuous carbon fiber bundle is not limited and can be used Figure 1 The fiber package manufacturing device is shown in the conceptual diagram.

[0095] Reference Figure 1 The fiber package manufacturing apparatus 100 includes a spreading area 110 , a splitting area 120 , and a winding area 130 .

[0096] A continuous carbon fiber bundle 10 having a number NK of single fibers as a starting material is drawn out from a supply bobbin B1.

[0097] The undivided continuous carbon fiber bundle 10 drawn out from the supply bobbin B1 is first spread in the spread area 110 .

[0098] The spreader bar 111 provided in the spreading area 110 may be heated or reciprocated in the width direction of the continuous carbon fiber bundle 10 . The mechanism for this may refer to known techniques.

[0099] The continuous carbon fiber bundle 10 is originally flat, and its width is further expanded and its thickness is further reduced by friction with the stretching roller 111. The thickness of the continuous carbon fiber bundle 10 after passing through the stretching area 110 is not limited, but can typically be 0.05 to 0.2 mm.

[0100] If the continuous carbon fiber bundle 10 is sufficiently flat when supplied from the supply bobbin B1, the stretching region 110 may be omitted. For example, a carbon fiber bundle having a bundle width of 50 times or more its average thickness may be considered sufficiently flat.

[0101] Next, the continuous carbon fiber bundle 10 is fed to the splitting area 120 and partially split therein.

[0102] The dividing area 120 is provided with a rotating blade 121 for forming a slit in the continuous carbon fiber bundle 10 and a plurality of godet rollers 123 for controlling the traveling speed of the continuous carbon fiber bundle 10 .

[0103] The rotation axis of the rotating blade 121 is parallel to the width direction of the continuous carbon fiber bundle 10, which is traveling in the fiber direction. Multiple blades 122 are arranged at regular intervals in the circumferential direction on the outer periphery of the rotating blade 121 to intermittently form slits of a certain length along the fiber direction of the continuous carbon fiber bundle 10 at a regular interval. The slit length and the gap length between the slits can be controlled by adjusting the travel speed of the continuous carbon fiber bundle 10, the peripheral speed of the rotating blade 121, and the spacing between the blades 122.

[0104] The continuous carbon fiber bundle 10 is partially divided into n equal parts by intermittently forming slits along the fiber direction using the (n-1) rotating blades 121 arranged in a direction parallel to the width direction of the traveling continuous carbon fiber bundle 10 .

[0105] The number n is not limited, but is preferably 3 or more, more preferably 5 or more, and may be 10 or more.

[0106] As an example, the continuous carbon fiber bundle 10 is formed immediately after the slits extending in the fiber direction are intermittently formed by the four rotating blades 121. Figure 2A as well as Figure 2B shown.

[0107] For convenience, the fiber direction (length direction) of the continuous carbon fiber bundle 10 is the x direction, the width direction is the y direction, and the thickness direction is the z direction. Figure 2A is a top view of the continuous carbon fiber bundle 10 as viewed from the z direction, Figure 2B A cross section perpendicular to the x direction of the continuous carbon fiber bundle 10 (a cross section when cut along the yz plane) is shown.

[0108] like Figure 2A As shown, in the continuous carbon fiber bundle 10, four slit rows are formed, namely the first slit row A S1 , Second slit row A S2 , the third slit row A S3 and the fourth slit row A S4 .

[0109] First slit row A S1 It consists of a plurality of first slits S1 arranged in the x direction.

[0110] Second slit row A S2 It consists of a plurality of second slits S2 arranged in the x direction.

[0111] The third slit row A S3 It consists of a plurality of third slits S3 arranged in the x direction.

[0112] Fourth slit row A S4 It consists of a plurality of fourth slits S4 arranged in the x direction.

[0113] These four slit rows are formed by different rotating blades, and therefore have different positions in the y direction.

[0114] Slit length L S and the gap length L between the slits G It is constant within any slit array and is also common between different slit arrays.

[0115] Slit length L S Relative to the slit length L S and the gap length L between the slits G The ratio of L S / (L S +L G ) is usually 90% or more, preferably 95% or more, for example, 99%. Figure 2B As shown, the continuous carbon fiber bundle 10 is mostly divided into five sub-bundles 11 .

[0116] First slit row A S1 , Second slit row A S2 , the third slit row A S3 and the fourth slit row A S4 The positions in the y direction are set so that the widths of the five sub-bundles 11 are substantially the same. For example, when the number of single fibers in the continuous carbon fiber bundle 10 is 15K, the number of single fibers in each sub-bundle 11 is 3K±0.5K.

[0117] Slit length L S Not limited, but preferably longer than 25 mm, more preferably longer than 50 mm, and most preferably longer than 500 mm. S The slit length L may be 10 times or more, further 20 times or more, and further 30 times or more of the cut length when the continuous carbon fiber bundle 10 is cut to produce SMC. S For example, it can be more than 25mm and less than 50mm, more than 50mm and less than 100mm, more than 100mm and less than 200mm, more than 200mm and less than 500mm, more than 500mm and less than 1000mm, more than 1000mm and less than 1500mm, more than 1500mm and less than 2000mm, or more than 2000mm and less than 3000mm.

[0118] Length of gap between slits L G The length is not limited, and is, for example, 5 to 10 mm, and may be shorter than 5 mm.

[0119] exist Figure 2A In the example shown, in the first slit column A S1 and the second slit row A S2 , gap between slits G SThe positions of the second slit row A are staggered in the x direction. S2 and the third slit column A S3 Between and the third slit column A S3 and the fourth slit column A S4 Same as between.

[0120] In this way, the gap G between the adjacent slit rows is set to S The structure in which the positions of the ? are staggered in the x direction is not necessary. In one example, Figure 14 As shown, the gap G between all the slit columns can be S In another example, the inter-slit gap G can be made between a portion of the slit columns. S The position of the slits is aligned, and the gap between the slits G is made between the other slits. S The positions are staggered in the x direction.

[0121] The slit length L described above S , the gap length between slits L G , slit length L S Relative to the slit length L S and the gap length L between the slits G The ratio of L S / (L S +L G ), and the gap between the slits G S The position of is not limited to the case where the continuous carbon fiber bundle 10 is partially divided into five sub-bundles, and the same applies to the case where the continuous carbon fiber bundle 10 is partially divided into four or fewer sub-bundles or six or more sub-bundles.

[0122] The number of single fibers in the sub-bundles formed by dividing the continuous carbon fiber bundle 10 is preferably 5K or less, more preferably 4K or less, and even more preferably 3K or less, regardless of the number n.

[0123] The number of single fibers in the sub-bundles formed by dividing the continuous carbon fiber bundle 10 is preferably greater than 0.5 K, and more preferably greater than 1 K, regardless of the number n. When the number of single fibers is greater than 0.5 K, the straightness of the carbon fiber bundle is easily maintained, and the reinforcing effect tends to be relatively improved.

[0124] The above upper and lower limits can be arbitrarily combined. For example, the number of single fibers in the sub-bundles formed by dividing the continuous carbon fiber bundle 10 is independent of the number n, and is preferably 0.5K to 5K, more preferably 0.5K to 4K, and most preferably 1K to 3K.

[0125] Refer again Figure 1The continuous carbon fiber bundle 10, which has been partially divided into n strands in the dividing area 120, is transported to the winding area 130 and wound onto the winding bobbin B2 to form a package. The winding bobbin B2 is, for example, a paper tube, but is not limited thereto. When the package is in use, the winding bobbin B2 is removed and the continuous carbon fiber bundle can be unwound by removing it from the inside.

[0126] When winding the continuous carbon fiber bundle 10, no gaps are left between the sub-bundles 11. This is to prevent the sub-bundles 11 from interlocking between the portion wound first on the bobbin B2 and the portion wound later on top of it. By winding without gaps between the sub-bundles 11, the continuous carbon fiber bundle 10 can be prevented from becoming tangled or broken when being removed from the outside or unwound from the inside.

[0127] When the continuous carbon fiber bundle 10 is wound on the bobbin in such a manner that there is no gap between the sub-bundles 11, as shown in FIG. Figure 3 As shown, as long as the total width W of the continuous carbon fiber bundle 10 is larger than the width W of the sub-bundle s The sum of the narrow can be.

[0128] Figure 3 This is a cross-sectional view of a continuous carbon fiber bundle 10 cut perpendicular to the fiber direction. Five sub-bundles 11 are arranged without gaps in the y-direction. That is, adjacent sub-bundles 11 are not separated from each other, and any sub-bundle 11 overlaps its adjacent sub-bundle 11 at its edges.

[0129] The width of the carbon fiber bundle can be reduced by guiding the carbon fiber bundle with a guide narrower than the width of the carbon fiber bundle. s The continuous carbon fiber bundle 10 is wound onto the winding frame B2 in a state where the sum of the widths of the sub-bundles is narrow. For example, a grooved roller having a groove width narrower than the sum of the widths of the sub-bundles can be used to guide the partially divided continuous carbon fiber bundle to the winding frame. Alternatively, the width of the fiber bundle guide of the traversing device can be made narrower than the sum of the widths of the sub-bundles.

[0130] When the total width of the continuous carbon fiber bundle is narrowed by this method, not only will the sub-bundles overlap, but some of the sub-bundles may also be folded in the width direction. Therefore, the overlap between the sub-bundles in the continuous carbon fiber bundle wound on the winding bobbin is not limited to Figure 3 The manner shown can be varied.

[0131] In order to reliably prevent gaps from existing between sub-bundles, the total width of the continuous carbon fiber bundle 10 when wound on the winding bobbin is preferably 90% or less, more preferably 80% or less, of the sum of the widths of the sub-bundles.

[0132] The total width of the continuous carbon fiber bundle when wound on the winding bobbin is not limited, but it is preferably not narrowed to be equal to the width of the sub-bundle. In particular, when the number of sub-bundles is greater than n, if the total width is too small, the bundle will easily collapse.

[0133] A traverse device (not shown) is usually provided in the winding area 130 .

[0134] When the continuous carbon fiber bundle 10 is traverse-wound on the winding bobbin B2, the oblique angle at the start of winding is, for example, 5 to 30°, and the oblique angle at the end of winding is, for example, 2 to 17°, although not limited thereto.

[0135] The winding ratio indicates how many times the spool rotates during one reciprocating motion of the traverse guide, and can also be referred to as the number of windings per traverse cycle. When the wire is wound around the spool at a constant winding ratio, if the winding ratio is an integer, the wire is wound around the spool at the same position during all traverse cycles, a phenomenon known as ribbon winding, which can lead to poor unwinding properties.

[0136] When the decimal point of the winding ratio is a multiple of 1 / p (p is an integer greater than 2), the wire is wound at the same position on the winding frame each time it moves horizontally for p cycles. Therefore, when p is particularly small, the loosening property may deteriorate, just like when the winding ratio is an integer.

[0137] Therefore, when the continuous carbon fiber bundle 10 is wound on the winding bobbin B2, the winding ratio is usually not an integer, and the decimal point of the winding ratio is preferably not a multiple of 1 / 2, 1 / 3, 1 / 4, or 1 / 5.

[0138] 1.2.SMC manufacturing equipment

[0139] A conceptual diagram of an SMC manufacturing apparatus preferably usable in the SMC manufacturing method of this embodiment is shown in FIG. Figure 4 shown.

[0140] Reference Figure 4 The SMC manufacturing apparatus 200 includes a first resin coating area 210, a second resin coating area 220, a cutting area 230, a deposition area 240, and an impregnation area 250. A fragmentation processing device 260 is disposed between the cutting area 230 and the deposition area 240.

[0141] In the first resin coating area 210 , a first coater 211 including a doctor blade is provided to form a first resin layer 51 composed of a thermosetting resin composition 50 on the first carrier film 41 unrolled from a roll.

[0142] In the second resin coating area 220 , a second coater 221 equipped with a doctor blade is provided to form a second resin layer 52 composed of the same thermosetting resin composition 50 on the second carrier film 42 unrolled from the roll.

[0143] In the cutting area 230, a rotary cutter 231 is provided for cutting the continuous carbon fiber bundle 10 drawn out from a package (which can be pulled out from a winding frame).

[0144] Rotating cutter 231 as Figure 5 The cutter roller 234 is provided with a plurality of blades 235 spaced at regular intervals in the circumferential direction on the outer periphery of the cutter roller 234, which can continuously cut the chopped carbon fiber bundle 20 having a certain fiber length from the continuous carbon fiber bundle 10.

[0145] Typically, a plurality of continuous carbon fiber bundles 10 are simultaneously aligned in parallel with each other within a plane parallel to the rotation axis direction of the rotary cutter 231 and supplied to the rotary cutter 231 .

[0146] The rotation axis direction of the rotary cutter 231 is the direction of the rotation axis of the rollers included in the rotary cutter 231, that is, the direction of the rotation axis of the cutting roller 234. The rotation axis directions of the guide roller 232 and the pinch roller 233 are also the same as the direction of the rotation axis of the cutting roller 234.

[0147] The deposition area 240 is located below the cutting area 230. The first carrier film 41 is transported from the first resin coating area 210 through the deposition area 240 to the impregnation area 250. As the first carrier film 41 travels through the deposition area 240, the chopped carbon fiber bundles 20 produced in the cutting area 230 fall and accumulate on the first resin layer 51 formed on the surface of the first carrier film 41, thereby forming the carbon fiber stack 30.

[0148] A mechanism for gradually bringing the first carrier film 41 and the second carrier film 42 closer together is located upstream of the impregnation zone 250. An impregnator 251 is located in a key area of the impregnation zone 250. The impregnator 251 includes two upper and lower conveyor belts, each equipped with rollers for pressing the laminate so that it is sandwiched between the conveyor belts. The impregnator 251 is configured to convey the laminate, comprising the carbon fiber stack 30 and the thermosetting resin composition 50, sandwiched between the first and second carrier films 41, 42, from above and below.

[0149] The fragmentation processing device 260 is arranged between the cutting area 230 and the stacking area 240. Figure 6The cover 261 is shown, along with a guide plate 262 disposed inside the cover and a pair of pin rollers (a first pin roller 263a and a second pin roller 263b). The first pin roller 263a and the second pin roller 263b have substantially the same axial length and their rotation axes are parallel to each other.

[0150] In the SMC manufacturing apparatus 200, the fragmentation device 260 is arranged so that the rotation axes of the first and second pin rollers 263a and 263b are parallel to the rotation axis of the rotary cutter 231. The fragmentation device 260 is preferably located directly below the rotary cutter 231.

[0151] Reference Figure 7 The first pin roller 263a includes a cylinder 264a and a plurality of pins 265a having the same shape and size are arranged on the surface of the cylinder 264a. The cylinder 264a and the pins 265a are both rigid bodies, for example, formed of metal.

[0152] The diameter of the cylinder 264a is not limited, and may be, for example, 60 mm to 150 mm.

[0153] The pin 265a extends perpendicularly to the rotation axis of the first pin roller 263a and has a cylindrical shape, for example, though not limited thereto. The boundary between the end surface and the peripheral surface of the pin 265a may be chamfered.

[0154] The diameter of the pin 265a is not limited, and may be, for example, 1 mm to 5 mm.

[0155] The length of the pin 265a, that is, the distance from the tip to the base of the pin is not limited, and may be, for example, 10 mm to 50 mm.

[0156] The pin 265a preferably has a circular cross section in order to prevent fuzzing of the chopped carbon fiber bundle 20 processed by the fragmentation processing device 260. The pin 265a may also have a conical or truncated cone shape whose diameter decreases toward the front end.

[0157] The arrangement of the pins 265a on the peripheral surface of the cylinder 264a is preferably overlapped with the original arrangement when the pins 265a are shifted by 5 mm to 20 mm in the axial direction and by 4 mm to 30 mm in the circumferential direction.

[0158] For example, in Figure 7 In the case of the cylinder 264a shown in FIG. 1 , when the circumferential surface is unfolded, as shown in FIG. Figure 8 As shown, pins 265a are arranged at each vertex of an equilateral triangle (indicated by a dotted line) with one side parallel to the axial direction. When the length of one side of the equilateral triangle is, for example, 5 mm, Figure 8 The configuration of pins 265a is shown overlapping the original configuration while being axially offset by 2.5 mm and circumferentially offset by approximately 4.3 mm.

[0159] In this specification, the maximum radius of a pin roller is defined as the distance from its rotation axis to the pin tip. In the first pin roller 263a, the radius of the cylinder 264a is preferably at least half of the maximum radius of the first pin roller 263a, and more preferably at least 75%. This is because the higher the ratio of the cylinder radius to the maximum radius of the pin roller, the smaller the difference in peripheral velocity between the pin tip and the pin base during pin roller rotation.

[0160] The above description of the first pin roller 263a is also applicable to the second pin roller 263b.

[0161] Although not limited, in order to reduce the cost of designing, manufacturing and maintaining the fragmentation processing device 260, it is preferred to make the design and specifications of the first pin roller 263a and the second pin roller 263b consistent in as many items as possible, including the maximum radius, cylinder diameter, pin shape, size, number and configuration.

[0162] Reference Figure 9 In the fragmentation processing device 260, the maximum radius r of the first pin roller 263a is M1 and the maximum radius r of the second pin roller 263b M2 The sum of the two pin rollers is greater than the distance d between the rotation axes of the two pin rollers. 12 big.

[0163] The maximum radius r of the first pin roller 263a M1 and the radius r of the cylinder 264b of the second pin roller C2 The sum of the two pin rollers is greater than the distance d between the rotation axes of the two pin rollers. 12 Similarly, the maximum radius r of the second pin roller 263b is M2 and the radius r of the cylinder 264a of the first pin roller C1 The sum of the two pin rollers is also greater than the distance d between the rotation axes of the two pin rollers. 12 Small.

[0164] The maximum radius r of the first pin roller 263a M1 and the maximum radius r of the second pin roller 263b M2 The sum of the distance d from the axis of rotation 12 The difference {(r M1 +r M2 )-d 12} is not limited, for example, it can be less than 20 mm, less than 15 mm, less than 10 mm or less than 5 mm.

[0165] The first pin roller 263a and the second pin roller 263b are driven to rotate by a driving mechanism (not shown). The rotation speeds of the first pin roller 263a and the second pin roller 263b can be independently controlled.

[0166] The rotation direction of the first pin roller 263a and the second pin roller 263b is as follows: Figure 6That is, the first pin roller 263a rotates in a manner that the pins move downward from the top on the side facing the second pin roller 263b, and the second pin roller 263b rotates in a manner that the pins move downward from the top on the side facing the first pin roller 263a.

[0167] In order to prevent the chopped carbon fiber bundle 20 from being stuck between the two pin rollers, it is advantageous to rotate both the first pin roller 263a and the second pin roller 263b.

[0168] Essentially all of the chopped carbon fiber bundles 20 produced in the cutting area 230 pass between the cylinder 264a of the first pin roller 263a and the cylinder 264b of the second pin roller 263b and land in the accumulation area. This reduces the chance of variations in the landing positions corresponding to the bundle size of the chopped carbon fiber bundles 20. Therefore, even when the bundle size of the chopped carbon fiber bundles 20 varies widely, the carbon fiber layer 30 can be easily made uniform along the thickness direction.

[0169] In a modified embodiment, the maximum radius r of the first pin roller 263a in the fragmentation processing device 260 is M1 and the maximum radius r of the second pin roller 263b M2 The sum of the two pin rollers can be the distance d between the rotation axes of the two pin rollers 12 In other modified embodiments, the maximum radius r of the first pin roller 263a in the fragmentation processing device 260 is M1 and the maximum radius r of the second pin roller 263b M2 The sum of the two pin rollers can be slightly smaller than the distance d between the rotation axes of the two pin rollers 12 , their difference {d 12 -(r M1 +r M2 )} is preferably 10 mm or less, more preferably 5 mm or less.

[0170] 1.3.SMC Manufacturing Method

[0171] The SMC manufacturing method of this embodiment will be described by taking as an example a case where the SMC manufacturing apparatus 200 described in 1.2. above is used.

[0172] (Extraction process)

[0173] In the drawing-out step, a continuous carbon fiber bundle is drawn out from a previously prepared package of the continuous carbon fiber bundle. The number of single fibers in the continuous carbon fiber bundle is NK, and the continuous carbon fiber bundle is partially divided into n sub-bundles in advance.

[0174] In this step, the bobbin package may be mounted on a creel and the continuous carbon fiber bundle may be drawn out from the outside, or the continuous carbon fiber bundle may be drawn out from the inside of the package after the bobbin is removed.

[0175] As previously mentioned, when producing a package, the continuous carbon fiber bundle is wound around the bobbin with adjacent sub-bundles overlapping. Therefore, the continuous carbon fiber bundle unwound from the package includes portions where the sub-bundles are adhered to each other with some overlap.

[0176] (Cutting process)

[0177] In the cutting process, the drawn-out continuous carbon fiber bundle 10 is supplied to the cutting area 230 and continuously cut by the rotary cutter 231, thereby producing chopped carbon fiber bundles 20 having a predetermined fiber length. The produced chopped carbon fiber bundles 20 fall toward the fragmentation processing device 260 located below the rotary cutter 231.

[0178] The fiber length of the chopped carbon fiber bundle 20 is not limited, and is, for example, 5 to 100 mm, preferably 20 to 60 mm, and typically, can be about 13 mm, about 25 mm, or about 50 mm.

[0179] (Fragmentation process)

[0180] As previously mentioned, the continuous carbon fiber bundle unwound from the package includes portions where the sub-bundles partially overlap and adhere to each other. The chopped carbon fiber bundles produced in the cutting step include a certain number of fiber bundles where the number of single fibers produced by cutting this portion exceeds {(N / n) + 0.5}K. The purpose of the fragmentation process is to fragment these fiber bundles using a fragmentation device to improve the single fiber distribution of the chopped carbon fiber bundles in the carbon fiber stack formed in the subsequent stacking process.

[0181] In the fragmentation processing device 260 , at least a portion of the chopped carbon fiber bundle 20 falling from the rotary cutter 231 contacts at least one of the first pin roller 263 a and the second pin roller 263 b and is divided into a plurality of fragments by the impact.

[0182] This fragmentation process is not intended to unravel the yarn. That is, the chopped carbon fiber bundles do not become loose until they are reduced to single fibers or a state close to that. In a preferred embodiment, the circumferential speed of the pin tips of the first and second pin rollers 263a, 263b is set so that the fragmentation process does not produce fiber bundles or single fibers with a single fiber count of 0.5K or less, or, if produced, the content of these fibers in the carbon fibers deposited on the first carrier film 41 is less than 1% by weight.

[0183] One reason for setting the rotational directions of the first and second pin rollers 263a and 263b so that the pins move downward on the opposite sides is to prevent strong shearing forces from being applied to the chopped carbon fiber bundles 20 passing between the two pin rollers. Strong shearing forces are believed to cause fuzzing of the carbon fiber bundles or a decrease in their straightness.

[0184] To achieve this purpose more effectively, the rotation speeds (rpm) of the first pin roller 263a and the second pin roller 264b are preferably set so that the peripheral speed of the tip of the pin 265a of the former is equal to the peripheral speed of the tip of the pin 265b of the latter.

[0185] (Resin coating process)

[0186] In the resin coating process, a first resin layer 51 composed of a thermosetting resin composition 50 is formed on a first carrier film 41 drawn out from a roller using a first coater 211, while a second resin layer 52 composed of the same thermosetting resin composition 50 is formed on a second carrier film 42 drawn out from another roller using a second coater 221.

[0187] The thermosetting resin composition 50 is a fluid paste containing a thermosetting resin as a main component, a tackifier and a curing agent, and optionally additives such as a reactive diluent, a low shrinkage agent, a filler, and a flame retardant.

[0188] Typical examples of the thermosetting resin include epoxy resin, vinyl ester resin, unsaturated polyester resin, polyimide resin, maleimide resin, and phenol resin, and two or more selected from these may be used in combination.

[0189] From the viewpoint of good adhesion to carbon fibers, the thermosetting resin is preferably an epoxy resin, a vinyl ester resin, or an unsaturated polyester resin.

[0190] The specific composition of the thermosetting resin composition may be determined by referring to the prior art as appropriate.

[0191] (Stacking process)

[0192] In the accumulation step, the chopped carbon fiber bundles 20 processed by the fragmentation processing device 260 fall onto the first carrier film 41 being transported below the fragmentation processing device 260. The fallen chopped carbon fiber bundles 20 are accumulated on the first resin layer 51 formed on the surface of the first carrier film 41, forming the carbon fiber stack 30.

[0193] (Immersion process)

[0194] The first carrier film 41 carrying the carbon fiber stack 30 deposited on the first resin layer 51 is bonded to the second carrier film 42 with the second resin layer 52 formed thereon facing downward while being conveyed toward the impregnator 251 .

[0195] The laminated body formed by lamination is pressurized by the impregnation machine 251 , and the carbon fiber stack 30 is impregnated with the thermosetting resin composition 50 .

[0196] After the impregnation process is complete, the impregnated carbon fiber stack 30 is wound around a bobbin, sandwiched between the first and second carrier films 41, 42. It then undergoes an optional aging process to form an SMC product. During the aging process, the thermosetting resin composition 50 becomes semi-cured due to the added tackifier, increasing its viscosity.

[0197] 1.4. SMC Manufacturing Method of Modified Embodiment

[0198] In the SMC manufacturing method described in Item 1.3., a continuous carbon fiber bundle having NK single fibers and partially divided into n sub-bundles is used as the raw material. In the SMC manufacturing method of the modified embodiment, a continuous carbon fiber bundle that has not been partially divided can be used as the raw material.

[0199] Therefore, the following SMC manufacturing method is also included in the embodiment of the present invention.

[0200]

[36] A method for manufacturing SMC, comprising: cutting a continuous carbon fiber bundle into chopped carbon fiber bundles using a rotary cutter; depositing the chopped carbon fiber bundles on a carrier film traveling below the rotary cutter to form a carbon fiber pile; and impregnating the carbon fiber pile in a thermosetting resin composition; and fragmenting the chopped carbon fiber bundles before being deposited on the carrier film using the following fragmentation processing device (A):

[0201] (A) A first pin roller and a second pin roller each having a rotation axis parallel to the rotation axis direction of the rotary cutter are provided, the first pin roller is driven to rotate on the side facing the second pin roller so that the pin moves from top to bottom, and the second pin roller is driven to rotate on the side facing the first pin roller so that the pin moves from top to bottom.

[0202]

[37] The manufacturing method as described in

[36] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is greater than the distance between the rotation axes of the first pin roller and the second pin roller.

[0203]

[38] The manufacturing method as described in

[37] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is larger than the distance between the rotation axes of the first pin roller and the second pin roller.

[0204]

[39] The manufacturing method as described in

[36] , wherein the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is smaller than the distance between the rotation axes of the first pin roller and the second pin roller, and the difference between them is less than 10 mm.

[0205]

[40] The manufacturing method as described in any one of

[36] to

[39] , wherein the radius of the cylinder in each of the first pin roller and the second pin roller is more than half of the maximum radius.

[0206]

[41] A manufacturing method as described in any one of

[36] to

[40] , wherein the circumferential speed of the pin front end of the first pin roller is equal to the circumferential speed of the pin front end of the second pin roller.

[0207]

[42] The manufacturing method according to any one of

[36] to

[41] , wherein the content of carbon fiber bundles having a single fiber count exceeding 0.5K in the carbon fiber stack is 99% by weight or more.

[0208]

[43] The manufacturing method according to any one of

[36] to

[42] , wherein the carbon fiber stack is pressurized together with the thermosetting resin composition in order to impregnate the carbon fiber stack in the thermosetting resin composition.

[0209]

[44] The manufacturing method according to any one of

[36] to

[43] , wherein at least a portion of the thermosetting resin composition is applied to the upper surface of the carrier film before the chopped carbon fiber bundles are stacked to form the carbon fiber stack.

[0210] 2. Experimental Results

[0211] The following describes the results of experiments conducted by the present inventors.

[0212] Experiment 1

[0213] (Preparation of partially split continuous carbon fiber bundles)

[0214] As the starting material, a flat continuous carbon fiber bundle (TR50S15L manufactured by Mitsubishi Chemical Corporation) with a single fiber count of 15K, an initial width of 8 mm, and a thickness of 0.1 mm was prepared. Using a cutter with four rotating blades, four rows of slits with a length of 1000 mm and a gap length of 5 mm between the slits were formed to partially divide the continuous carbon fiber bundle into five sub-bundles with a width of 1.6 mm. The position of the gaps between the slits in the fiber direction was the same in all rows of slits.

[0215] After partial splitting, the continuous carbon fiber bundle was wound onto a paper bobbin with a diameter of 82 mm and a length of 280 mm at a traverse length of 254 mm to produce a square-end package. The width of the guide that guides the fiber bundle was adjusted to maintain the total width of the continuous carbon fiber bundle at 6 mm or less during winding.

[0216] (Production of carbon fiber stacks)

[0217] In addition to not having a fragmentation processing device, the use of Figure 4 An SMC manufacturing apparatus having the same structure as that shown in the figure produces a carbon fiber pile from a continuous carbon fiber bundle having 15K single fibers which has been prepared in the above-mentioned steps and partially divided into five sub-bundles.

[0218] A plurality of continuous carbon fiber bundles were supplied to a rotary cutter in a state of being arranged in parallel at equal intervals, and were cut every 25.4 mm.

[0219] The chopped carbon fiber bundles fell onto a carrier film not coated with a thermosetting resin composition, which was traveling below the rotary cutter at a linear speed of 5 m / min. The fallen chopped carbon fiber bundles accumulated on the carrier film to form a carbon fiber pile.

[0220] (Determination of Single Fiber Number Distribution)

[0221] From the carbon fiber stack prepared in the above steps, an area of approximately 21 cm × 30 cm stacked near the center line of the carrier film is selected and the weight of all chopped carbon fiber bundles (300 or more) contained in this area is measured. The single fiber number distribution of the chopped carbon fiber bundles in the carbon fiber stack is obtained by converting the measured weight into the single fiber number. Figure 10 shown.

[0222] The content of carbon fiber bundles having a single fiber count exceeding 0.5K in the produced carbon fiber layer is 99.9% by weight or more.

[0223] Experiment 2

[0224] A carbon fiber stack was produced using the same SMC manufacturing apparatus as used in Experiment 1, except that the apparatus was equipped with a fragmentation processing device. The single fiber number distribution was measured in the same manner as in Experiment 1. The procedure for producing the carbon fiber stack was the same as in Experiment 1, except that the chopped carbon fiber bundles were fragmented using the fragmentation processing device before being deposited on the carrier film.

[0225] The structure and Figure 4 The SMC manufacturing equipment shown has the same structure. Both pin rollers are made of metal and have the same construction. The pins arranged on the cylindrical surface have a diameter of 3 mm and a length of 20 mm, respectively. The pins on the cylindrical surface of each pin roller are arranged periodically, overlapping with the original arrangement when staggered 7.5 mm in the axial direction and 6.5 mm in the circumferential direction. The sum of the maximum radii of the two pin rollers is 10 mm greater than the distance between the two pin rollers' rotational axes.

[0226] The two pin rollers rotate so that the peripheral speed of the front end of any one pin is 377 m / min, and the pin moves from top to bottom on the side facing the other pin roller.

[0227] The single fiber number distribution of the chopped carbon fiber bundle in the prepared carbon fiber stack is as follows: Figure 11 shown.

[0228] The content of carbon fiber bundles having a single fiber count exceeding 0.5K in the produced carbon fiber layer is 99.9% by weight or more.

[0229] Experiment 3

[0230] A carbon fiber stack was prepared in the same manner as in Experiment 2, except that the two pin rollers were rotated so that the pins on the side facing the other pin roller moved upward from bottom to top, and the single fiber number distribution was measured.

[0231] The single fiber number distribution of the chopped carbon fiber bundle in the prepared carbon fiber stack is as follows: Figure 12 shown.

[0232] It was found that in the fragmentation treatment of Experiment 3, the chopped carbon fiber bundles tended to be fragmented finer than in the fragmentation treatment of Experiment 2.

[0233] Experiment 4

[0234] A carbon fiber pile was prepared in the same manner as in Experiment 2, except that the two pin rollers were rotated in the same direction, and the single fiber number distribution was measured.

[0235] The single fiber number distribution of the chopped carbon fiber bundle in the prepared carbon fiber stack is as follows: Figure 13 shown.

[0236] It was found that in the fragmentation treatment of Experiment 4, the chopped carbon fiber bundles tended to be fragmented finer than in the fragmentation treatment of Experiment 2.

[0237] Experiment 5

[0238] A carbon fiber pile was prepared in the same manner as in Experiment 2, except that the distance between the rotation axes of the two pin rollers was made equal to the sum of the maximum radii of the two pin rollers, and the single fiber number distribution thereof was measured.

[0239] The single fiber number distribution of the chopped carbon fiber bundle in the prepared carbon fiber stack is as follows: Figure 15 shown.

[0240] Experiment 6

[0241] A flat continuous carbon fiber bundle with 15,000 single fibers (15K), an initial width of 8 mm, and a thickness of 0.1 mm was prepared. After being partially split, it was wound onto a paper bobbin with a diameter of 82 mm and a length of 280 mm at a traverse length of 254 mm to produce a square-end fiber package. No expansion was performed using a spreader.

[0242] A cutter with four rotating blades was used to partially split the continuous carbon fiber bundle. Four rows of slits, each 1000 mm long and with a 5 mm gap between them, were formed to split the continuous carbon fiber bundle into five partially interconnected sub-bundles, each 1.6 mm wide. The position of the gaps between the slits in the fiber direction was the same for all rows of slits.

[0243] During the winding, the bevel angle at the start of the winding was 9.9°, the bevel angle at the end of the winding was 5°, the winding ratio was 11.30, and the winding amount was 5.0 kg.

[0244] By adjusting the groove width of the grooved roller through which the continuous carbon fiber bundle passes after the splitting process, the winding frame was pulled out from the fiber package produced by 6 mm, in which the total width of the continuous carbon fiber bundle wound on the winding frame was 75% of the sum of the sub-bundle widths. No particular problems were found when the continuous carbon fiber bundle was pulled out from the inside.

[0245] In contrast, in a fiber package manufactured in the same manner, except that the total width of the continuous carbon fiber bundle wound on the bobbin is 8 mm, which is the same as the sum of the widths of the sub-bundles, entanglement occurs relatively frequently when the bobbin is pulled out and the continuous carbon fiber is extracted from the inside.

[0246] The present invention has been described above based on specific embodiments, and each embodiment is provided as an example and does not limit the scope of the present invention. The embodiments described in this specification can be modified in various ways without departing from the scope of the invention, and the features described in other embodiments can be combined within the scope of implementation.

[0247] Description of Reference Numerals

[0248] 10: continuous carbon fiber bundle;

[0249] 11: sub-bundle;

[0250] 20: chopped carbon fiber bundles;

[0251] 100: Fiber package manufacturing device;

[0252] 110: stretching area;

[0253] 120: segmentation area;

[0254] 130: winding area;

[0255] 200: SMC manufacturing equipment;

[0256] 210: first resin coating area;

[0257] 220: second resin coating area;

[0258] 230: Cut off area;

[0259] 240: accumulation area;

[0260] 250: impregnation area;

[0261] 260: Fragmentation processing device.

Claims

1. A method for manufacturing SMC, wherein: Include: (i) extracting from a package a continuous carbon fiber bundle having a single fiber number NK which has been partially divided into n sub-bundles in advance; (ii) cutting the continuous carbon fiber bundle drawn out from the package into chopped carbon fiber bundles using a rotary cutter; (iii) depositing the chopped carbon fiber bundles on a carrier film traveling below the rotary cutter to form a carbon fiber stack; as well as (iv) impregnating the carbon fiber stack in a thermosetting resin composition; In the continuous carbon fiber bundle wound into the package, the total width is smaller than the sum of the widths of the sub-bundles, The chopped carbon fiber bundle before being deposited on the carrier film is subjected to fragmentation treatment using the following (A) fragmentation treatment device: (A) A first pin roller and a second pin roller each having a rotation axis parallel to the rotation axis direction of the rotary cutter are provided, the first pin roller is driven to rotate on the side facing the second pin roller so that the pin moves from top to bottom, and the second pin roller is driven to rotate on the side facing the first pin roller so that the pin moves from top to bottom.

2. The manufacturing method according to claim 1, wherein The sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is greater than or equal to the distance between the rotation axes of the first pin roller and the second pin roller.

3. The manufacturing method according to claim 2, wherein: The sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is greater than the distance between the rotation axes of the first pin roller and the second pin roller.

4. The manufacturing method according to claim 1, wherein The sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is smaller than the distance between the rotation axes of the first pin roller and the second pin roller, and the difference between the sum of the maximum radius of the first pin roller and the maximum radius of the second pin roller is less than 10 mm.

5. The manufacturing method according to any one of claims 1 to 4, wherein: In the package, the continuous carbon fiber bundle is wound so that no gaps exist between the sub-bundles.

6. The manufacturing method according to any one of claims 1 to 4, wherein: In the package, the continuous carbon fiber bundle is wound so that adjacent sub-bundles overlap.

7. The manufacturing method according to any one of claims 1 to 4, wherein: N is 15 or greater.

8. The manufacturing method according to any one of claims 1 to 4, wherein: In each of the first pin roller and the second pin roller, the radius of the cylinder is equal to or greater than half of the maximum radius.

9. The manufacturing method according to any one of claims 1 to 4, wherein: The peripheral speed of the pin tips of the first pin roller is equal to the peripheral speed of the pin tips of the second pin roller.

10. The manufacturing method according to any one of claims 1 to 4, wherein: The carbon fiber layer contains carbon fiber bundles having a single fiber count exceeding 0.5K in an amount of 99% by weight or more.

11. The manufacturing method according to any one of claims 1 to 4, wherein: The fragmentation treatment reduces the number of chopped carbon fiber bundles having a single fiber count greater than {(N / n)+0.5}K contained in the unit weight of the carbon fiber layer.

12. The manufacturing method according to any one of claims 1 to 4, wherein: In order to impregnate the carbon fiber stack in the thermosetting resin composition, the carbon fiber stack is pressurized together with the thermosetting resin composition.

13. The manufacturing method according to any one of claims 1 to 4, wherein: At least a portion of the thermosetting resin composition is coated on the upper surface of the carrier film before the step (iii).

Images