JP2008297330A - Fiber-reinforced tape and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fiber-reinforced tape in which the surface of the single fiber is sufficiently covered with a thermosetting resin, which has a uniform width and thickness while being thin, and which has both of high strength and flexibility. <P>SOLUTION: The fiber-reinforced tape comprising the thermosetting resin and a high-strength fiber-opened multifilament is constituted as follows. The single fibers having 0.1-5.5 dtex single fiber fineness are layered in the thickness direction so as to form one to three layers in the side cross section view of the tape, and the tape has &ge;10 ratio of width/thickness, and &le;7% variation coefficient of the width. The spaces among the single fibers are substantially filled with the thermosetting resin. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a fiber reinforced tape comprising a thermosetting resin and high strength fibers. More specifically, the present invention relates to a fiber reinforced tape that is thin and has both high strength and flexibility.

Conventionally, fiber reinforced composite materials in which fibers, etc. are mixed for the purpose of imparting strength, heat resistance, and wear resistance to matrix resins such as synthetic resins have been used in aerospace, transportation, various industrial parts, various sports materials, etc. It is used in a wide range of fields.
High-performance fibers such as carbon fibers, glass fibers, and aramid fibers are generally used as fibers used in such composite materials. Among them, aramid fibers are excellent in strength, flexibility, and light weight, so that they have been developed for various uses recently, and future expansion is expected.

In general, as one of fiber reinforced composite materials containing high-performance fibers as reinforcing fibers, it has been proposed to apply or impregnate a resin to a fiber multifilament tow to form a tape-like fiber reinforced composite material.
For example, Japanese Patent Application Laid-Open No. 2004-122416 proposes a lightweight composite tape-like material in which the surface of the opened reinforcing fiber is covered with a thermoplastic resin, and a method for manufacturing the same.

  Although this method has good productivity in obtaining a resin-impregnated tape-like fiber reinforced composite material, however, when it is applied to a general aramid fiber, the form of the aramid fiber is a monofilament (single yarn) having a diameter of about 12 μm. ) Is a multifilament, and strictly speaking, each single yarn is not arranged in a straight line, and is a fiber that is more flexible than carbon fiber or glass fiber. For this reason, there are problems that single yarns are easily entangled with each other and that the tape width varies depending on the tension.

  Furthermore, Japanese Patent Publication No. 4-7990 proposes a method of impregnating a thermoplastic resin in a state where the multifilament is sufficiently expanded in advance. Certainly, if this method is used, entanglement can be prevented to some extent and gaps can be created between single yarns, so it seems that it is easy to obtain a tape-like fiber reinforced composite material uniformly impregnated with resin. Although the patent mentions the method of expanding the multifilament, it does not specify the method of impregnation of the thermoplastic resin, so only the method shown in this patent is a thin leaf of a certain quality made of thermoplastic resin and aramid fiber. Insufficient to obtain a tape.

Japanese Patent Laid-Open No. 2003-73978 proposes a tape-like thread-like manufacturing method in which high-performance fiber multifilaments such as aramid fibers are resin-treated and then opened by a specific method. Although a fiber having a high degree of opening can be obtained, there has been a problem that variations in tape width and thickness are large.
In view of these points, a fiber reinforced tape having a uniform width and thickness and a method for producing the same have been highly desired.

JP 2004-122416 A Japanese Examined Patent Publication No. 4-7990 JP 2003-73978 A

  An object of the present invention is a fiber comprising a high-strength fiber filament that is sufficiently coated with a thermosetting resin on the surface of a single yarn, is uniform in width and thickness, and is both thin and high in strength and flexibility. It is to provide a reinforced tape.

  As a result of intensive studies to solve the problems in the previous period, the present inventors set the spread multifilament to a certain degree of spread, applied a tension of 1/100 or more of its breaking strength in the length direction, and thermosetting By impregnating the resin so that the fluctuation of the width before and after impregnation with the conductive resin is controlled to 20% or less, the surface of the single yarn is sufficiently coated with the thermoplastic resin, and the width and thickness are controlled within a specific range. It was found that the fiber reinforced tape can be solved.

  As described above, a fiber reinforced tape having a certain range of width and thickness can be obtained by setting a certain degree of opening and carrying out a specific tension condition during resin impregnation. It becomes the quality which can be used conveniently for composite materials, such as a shape.

Hereinafter, embodiments of the present invention will be described in detail.
Examples of fibers used in the fiber-reinforced tape of the present invention include aromatic polyamide fibers, carbon fibers, glass fibers, polyparaphenylene benzobisoxazole fibers, aromatic polyester fibers, ultrahigh molecular weight polyethylene fibers, and polyether ether ketone fibers. Examples include polyketone fibers. Among them, aromatic polyamide fibers having high strength and flexibility are preferably used.

  Aromatic polyamide fibers are classified into a para type and a meta type. The para type has high strength and elastic modulus, and the meta type has excellent flame retardancy and long-term heat resistance. Either of them may be used in the present invention. Specifically, as the para-type aramid fiber, polyparaphenylene terephthalamide fiber ("Kevlar" manufactured by Toray DuPont Co., Ltd., "Twaron" manufactured by Teijin Towaron Co., Ltd.), and copolyparaphenylene-3,4'- Examples include oxydiphenylene terephthalamide fiber (“Technora” manufactured by Teijin Techno Products Co., Ltd.), and poly-araphenylene isophthalamide fiber (“Nomex” manufactured by DuPont, Teijin Techno Products Co., Ltd.). Manufactured "Conex" etc.). Of these, polyparaphenylene terephthalamide fiber and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber are preferably used.

  A small amount of various surfactants may be adhered to the surface of the fiber in order to improve resin impregnation property, or the treatment agent (oil agent etc.) applied in the fiber manufacturing process may be used as it is without being removed. .

  The single fiber fineness of the fiber is in the range of 0.1 to 5.5 dtex, preferably 0.3 to 2.5 dtex. If it is less than 0.1 dtex, there are many difficult points in the spinning technology, and it is not only difficult to stably produce fibers of good quality due to the occurrence of yarn breakage and fluff, but it is also preferable because the cost increases. Absent. On the other hand, if it exceeds 5.5 dtex, the mechanical properties of the fiber, particularly the strength, is greatly reduced, and it is difficult to obtain a thin and uniform tape when a fiber reinforced tape is used.

  The fineness in the multifilament of the fiber is 220-20000 dtex, preferably 440-10000 dtex. When it exceeds 20000 dtex, it is difficult to stably open the multifilament, and as a result, the mechanical strength when the composite material is obtained decreases.

  The fiber reinforced tape of the present invention has a width / thickness ratio of 10 or more, preferably 20 or more and 1000 or less. When the ratio of width / thickness is less than 10, it is not preferable because an unimpregnated portion of the matrix resin covering the filament is likely to occur, and as a result, the performance when used as a composite material, particularly the tensile strength is lowered. Moreover, when it exceeds 1000, it is practically difficult to obtain a fiber reinforced tape reinforced with a fibrous material and having no gap in the width direction.

  The fiber reinforced tape of the present invention is preferably one in which one to three layers of single yarns overlap in the thickness direction. When three or more layers are overlapped, a portion where the resin is not impregnated is easily formed between the fibers, and the strength is lowered. One layer or less is not preferable because the fiber is not reinforced.

  Moreover, the fiber reinforced tape of the present invention is characterized in that the coefficient of variation of the width is 7% or less. When a composite material is created by, for example, winding a tape whose width coefficient of variation exceeds 7% and arranging a plurality of tapes, etc., the width is unstable, resulting in frequent gaps in the resulting composite material. A thin composite material cannot be obtained.

As a method for obtaining the above-described fiber-reinforced tape of the present invention, a tension of 1/100 or more of the breaking strength is applied to the multifilament before resin impregnation, the width variation coefficient is 7% or less, and the monofilament is in the thickness direction. After opening the fiber so as to be in a state where 1 to 3 layers are formed, the liquid resin is impregnated so that the variation in width is 20% or less before and after the resin is impregnated while maintaining the state. There is a method in which a fiber-reinforced tape is obtained by performing a fixing treatment with heat or the like.
The fibers are preferably arranged almost parallel to the length direction of the tape, but need not be completely parallel as long as the strength and flexibility are satisfied.

  In order to obtain the fiber reinforced tape of the present invention, before the resin impregnation, the multifilament has a coefficient of variation in width (CV; unit%) of 7% or less, preferably 5% or less, and the overlap of the single yarns in the thickness direction. It is necessary to be a multifilament opened so as to be between 1 to 3 layers, and in production it will be opened while pulling in the length direction with a certain tension. As a method for obtaining, specifically, a method in which fibers are passed through two gears having different curvatures described in Japanese Patent Publication No. 4-7990, and then the fibers are pulled to extend the curl and open, WO 2005/002819. The method of opening the fiber with a suction fluid after alternately creating a state of relaxation, tension, relaxation, tension, etc. by reciprocating back and forth locally in one direction crossing the fiber axis as described above is preferably used. It is done.

  The tension for pulling the opened multifilament needs to be 1/100 or more of the breaking strength of the opened multifilament. If the tension is less than 1/100, the width of the spread multifilament and the layer overlap of the single yarns cannot be controlled within the range, which is not preferable.

  The opened multifilament is impregnated with a liquid resin so that a tension of 1/100 or more of the breaking strength is maintained while maintaining the state, and the width fluctuation is 20% or less before and after impregnation with the resin. It is preferable to perform a fixing treatment by heat treatment or the like to obtain a fiber reinforced tape.

  There is no particular limitation on the thermosetting resin impregnated in the multifilament, phenol resin, epoxy resin, unsaturated polyester resin, vinyl ester resin, diallyl phthalate resin, cyanate ester resin, polyimide resin, bismaleimide triazine resin, polyphenylene ether resin, Examples thereof include a crosslinked polyaminoamide resin and a crosslinked polyesteramide resin. These may be copolymers, modified products, or resins in which two or more resins are mixed. Or in the resin, flame retardant, light proofing agent, UV absorber, smoothing agent, antistatic agent, antioxidant, mold release agent, plasticizer, colorant, antibacterial agent, pigment, conductive agent, silane coupling agent, inorganic A functional agent such as an inorganic coating agent or inorganic fine particles may be included. Among these, an epoxy resin is preferably used from the viewpoints of adhesion to high-strength fibers and mechanical strength.

  As a method for impregnating the resin, there are a roll coating method in which the resin is quantitatively applied with a mesh roll, a method in which the resin is introduced into the impregnation bath and a passage through the impregnation bath. Absent.

  The tension applied during the resin impregnation needs to be 1/100 or more of the breaking strength, and if it is less than 1/100, the fibers easily converge in the resin impregnation step, and the width / thickness ratio. However, it is difficult to obtain a tape of 10 or more, which is not preferable. Preferably, it is 1/100 to 1/10 of the breaking strength.

  In addition, it is important that the variation in width before and after impregnation with the resin is 20% or less. In order to suppress the fluctuation of the width to 20% or less, in addition to the tension adjustment described above, the multifilament opened in the resin impregnation process is always in contact with the guide roll so that the tension is kept within a certain range. It is preferable to do. Preferably, a tension measuring device is attached to the guide roll to control the tension within a predetermined range. Any impregnation device may be used as long as this condition is satisfied, but the tension and the yarn path are adjusted in advance by the device to be used, and a line is constructed so that the variation in width before and after the resin impregnation is 20% or less. Is preferred.

  Furthermore, the resin-impregnated fiber is immediately fixed with heat or the like to obtain a fiber reinforced tape. At this time, the resin solvent scatters and the fibers are concentrated at the same time. It is preferable to fix it by making it contact with a heating roll or the like made. However, the immobilization method is not limited to this, and any other method may be used as long as it can immobilize the multifilament without focusing.

  It is important to adjust the volume ratio of the resin in the fiber reinforced tape of the present invention between 10 and 70 vol%, and if it is out of this range, there is a possibility that the performance when used as a composite material cannot be exhibited sufficiently. If it is less than 10%, the strength is insufficient. If it is 70% or more, flexibility is insufficient, which is not preferable. Preferably it is 25-60 vol%.

  The fiber reinforced tape obtained in this way has a matrix resin applied almost evenly to each single yarn, so it exhibits high strength and is thin, so it has excellent flexibility and handleability. A good fiber reinforced tape can be provided.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the preparation method of the test piece used in the Example and its evaluation method are as follows.

(1) Fluctuation coefficient of width and width of opened multifilament N = 50 multifilament widths were measured every 1 cm in the length direction using a laser displacement meter, and the average value was taken as the width of the multifilament. The coefficient of variation was calculated using the following formula from the standard deviation value of the width of 50 locations and the average value of the multifilament width.
Coefficient of variation of width (%) = (standard deviation of width) / (average value of width) × 100

(2) Multifilament width before and after resin impregnation and rate of change of width N = 50 multifilaments immediately after passing through the resin bath in the same manner as in (1) above were measured every 1 cm in the length direction. The average value was defined as the multifilament width immediately after passing through the resin bath. Using this value and the multifilament width measured in (1), the following formula was used.
Width variation rate (%) = {(width before passing through the resin bath) − (width after passing through the resin bath)} / (width before passing through the resin bath) × 100

(3) Number of single yarns overlapped in the thickness direction of the multifilament Measure the thickness using calipers at any 10 points, and use this average value as the thickness of the multifilament. From this value and the single yarn diameter, Calculated.
Number of overlapping thickness (number) = (thickness of multifilament) / (single yarn diameter)

(4) Volume resin content in the tape The weight of the tape and the weight of the fiber before resin impregnation were measured and calculated using the following formula.
Content (%) = {(tape weight) − (fiber weight)} / (tape weight) × 100

(5) Tape Width and Coefficient of Variation of Width N = 50 tape widths were measured for each 1 cm in the length direction in the same manner as in (1), and the average value was taken as the tape width. The coefficient of variation was calculated from the standard deviation value of the width at 50 locations and the average value of the tape width using the following formula.
Coefficient of variation of tape width (%) = (standard deviation of tape width) / (average value of tape width) × 100

(6) Ratio of tape width and thickness The width and thickness were measured for any 10 points on the tape, the width was divided by the thickness, and the average of 10 points was taken as the ratio.

(7) Tensile strength of tape The obtained tape was subjected to treatment in an atmosphere of 130 ° C. for 2 hours under a load of 100 g to cure the resin, and then measured according to JIS C 2318.

[Example 1]
Using a copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber having a fineness of 1670 Dtex and 1000 filaments (“Technola” manufactured by Teijin Techno Products Co., Ltd.), the curvature described in Japanese Patent Publication No. 4-7990 After passing the fibers through two different gears, the fibers are expanded in the width direction by pulling the fibers with a tension of 600 g (about 1/65 of the breaking tension), extending the curls, and opening the multifilaments. Obtained. At this time, the multifilament width was 6.3 mm, the coefficient of variation in width was 3.5%, and the number of overlaps in the thickness direction was 1.9.

This multifilament is placed in an epoxy resin bath (resin composition: epoxy resin / curing agent / acetone / methanol = 40/20/20/20) in which three 20 mm diameter rotating rollers are submerged while applying a tension of 600 g. Pass at a speed of 1 m / min, and after passing through the resin bath, remove excess resin by sandwiching it between two rolls of rubber and metal, and immediately contact with a roll heated to 90 ° C. (contact time 1 minute). After removing and winding, a fiber reinforced tape was obtained. At this time, the variation rate of the multifilament width before and after passing through the resin bath was 12%.
With respect to this tape, the properties shown in the above (4) to (7) were as shown in Table 1.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that the spread multifilament obtained in Example 1 was used and passed through a resin bath under a tension of 100 g (about 1/400 of the breaking tension) to obtain a fiber reinforced tape. It was. At this time, the variation rate of the multifilament width before and after passing through the resin bath was 47%.
With respect to this tape, the properties shown in the above (4) to (7) were as shown in Table 1.

[Comparative Example 2]
Using the opened multifilament obtained in Example 1, while applying a tension of 600 g, it was passed through a resin bath in which one rotating roller having a diameter of 10 mm was submerged at a speed of 1 m / min, and then heated to 110 ° C. A fiber reinforced tape was obtained in the same manner as in Example 1 except that the solvent was removed by passing through a 1 m non-contact heater (the multifilament was not in contact with the guides during this time). At this time, the variation rate of the multifilament width before and after passing through the resin bath was 55%.
With respect to this tape, the properties shown in the above (4) to (7) were as shown in Table 1.

[Comparative Example 3]
Instead of using the opened multifilament obtained by the method shown in Example 1, copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber having a fineness of 1670 Dtex and a filament number of 1000 (manufactured by Teijin Techno Products Co., Ltd.) "Technora") was used to obtain a multifilament that was opened through five lines of 10 mm diameter bar guides that were alternately raised and lowered to prevent twisting while applying a tension of 1000 g. At this time, the multifilament width was 4.2 mm, the width variation coefficient was 8.1%, and the number of overlaps in the thickness direction was 2.9.

Using this multifilament, resin impregnation and solidification were performed in the same manner as in Example 1 to obtain a fiber reinforced tape. At this time, the variation rate of the multifilament width before and after passing through the resin bath was 24%.
With respect to this tape, the properties shown in the above (4) to (7) were as shown in Table 1.

  The fiber reinforced tape of the present invention has a uniform width and thickness and high tensile strength, and can be suitably used for composite materials such as resin belts or cylindrical bodies.

Claims (4)

  A tape comprising a thermosetting resin and a high-strength fiber-opening multifilament, and when the tape is viewed from a side cross section, a single yarn having a single fiber fineness of 0.1 to 5.5 dtex is 1 to 3 in the thickness direction. The tape has a width / thickness ratio of 10 or more, a coefficient of variation of the width of 7% or less, and a thermosetting resin is substantially filled between single yarns. Fiber reinforced tape.   The fiber-reinforced tape according to claim 1, wherein the high-strength fiber is polyparaphenylene terephthalamide or copolyparaphenylene-3,4'-oxydiphenylene terephthalamide.   The fiber reinforced tape according to claim 1, wherein the thermosetting resin is an epoxy resin. In a method for producing a fiber reinforced tape obtained by impregnating and solidifying a liquid thermosetting resin while a high-strength fiber opening multifilament having a single fiber fineness of 0.1 to 5.5 dtex is advanced by applying tensile tension in the length direction A method for producing a fiber-reinforced tape, wherein the resin impregnation is performed under conditions that satisfy the following requirements.
a) The tensile tension at the time of resin impregnation is 1/100 or more of the breaking strength of the spread multifilament.
b) When the high-strength fiber opening multifilament before resin impregnation is subjected to a tension of 1/100 or more of the breaking strength in the length direction, the width variation coefficient is 7% or less and The yarn is one to three layers in the thickness direction.
c) The width variation rate of the opened multifilament before and after the resin impregnation is 20% or less.
Width variation rate: (opening multifilament width-fiber reinforced tape width) / opening multifilament width