JP2008007871A - Reinforcing fiber sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a unidirectional reinforcing fiber sheet having excellent reinforcing effect and little lowering of the strength utilization rate even in the case of increasing the amount of the reinforcing fiber. <P>SOLUTION: The reinforcing fiber sheet contains a plurality of fiber group units composed of a reinforcing fiber and arranged in one direction. The fiber group is a reinforcing fiber group composed of intertwisted reinforcing fibers, a covering assistant fiber 2 crossing each reinforcing fiber group 1 is arranged on the top and back faces of the fiber sheet in the longitudinal direction of each reinforcing fiber group, the covering assistant fiber is bundled with a binding assistant fiber 3 to form a bag-shaped warp-knit texture, and the reinforcing fiber group is intercalated in multiple stages into the bag-shaped warp-knit texture. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reinforcing fiber sheet, and more particularly to a reinforcing fiber sheet suitable for reinforcing a structure such as a building or a molded body such as a pipe.

  2. Description of the Related Art In recent years, as a method for reinforcing civil engineering and building structures whose strength and durability have decreased due to aging and the like, a reinforcing method in which a fiber reinforced resin including a reinforcing fiber sheet is bonded to a structure to reinforce is attracting attention. Further, in the molding of pipes and the like made of fiber reinforced plastic, a molding method using a reinforcing fiber sheet as a reinforcing base material is frequently used.

  A typical example of the reinforcing fiber sheet that can be used in these methods is a reinforcing fiber sheet that uses high-strength fibers such as carbon fibers and aramid fibers. In such a reinforcing fiber sheet, when the reinforcing fibers are interlaced, crimping occurs, and the strength utilization rate of the high-strength fibers decreases. ing. In such a unidirectional reinforcing fiber sheet, in order to stabilize the form as a sheet, an auxiliary fiber is used separately from the reinforcing fiber, a woven structure is formed using the auxiliary fiber as a warp and a weft, and a reinforcing fiber group is formed. A retained reinforcing fiber sheet has been proposed (see, for example, Patent Document 1). However, even in this reinforcing fiber sheet, when stress is applied to the sheet, there is a risk that crimping will occur in the reinforcing fiber due to the tightening of the auxiliary fibers constituting the fabric.

  Further, the reinforcing fiber group is arranged in a unidirectional manner in a hook shape so as to hold the reinforcing fiber group using the knitted structure of the auxiliary fiber, and the surface of each reinforcing fiber group covers the reinforcing fiber group. There has been proposed a reinforcing fiber sheet in which fibers are arranged in the length direction of the reinforcing fiber group and the covering auxiliary fiber is entangled between adjacent reinforcing fiber groups and bound by a warp knitted structure with the auxiliary fiber (for example, a patent) Reference 2). In the reinforcing fiber sheet using the knitted structure, the covering auxiliary fiber is bound by the entanglement auxiliary fiber to form a bag-like warp knitting structure, and the reinforcing fiber group is inserted through the bag-like warp knitting structure. An organization is formed.

JP-A-7-243149 (Claims) JP 10-37051 A (Claims)

  Although the structure in which the reinforcing fiber group is inserted into the bag-shaped warp knitted structure is well thought out, the voids between the reinforcing fiber groups are taken in and arranged in consideration of the permeability of the adhesive. However, it does not take into consideration the case where the reinforcing fibers are densely arranged in order to improve the reinforcing property. Therefore, in order to ensure a sufficient reinforcing effect, it is necessary to increase the fineness per group of reinforcing fibers to be inserted through, but there is a problem. That is, since the reinforcing fiber group is supplied to the knitting machine and inserted, as the fineness per reinforcing fiber group increases, the process passability decreases, and the guide, wrinkle, By rubbing at a bent portion such as a needle, a yarn length difference is likely to occur between the reinforcing fiber single yarns. As a result, in the reinforcing fiber sheet, there is a problem that a tensile strength as high as a value calculated from the strength of the reinforcing fiber raw yarn and the amount of the reinforcing fiber used cannot be obtained, that is, the strength utilization rate is lowered.

  In view of such a situation, an object of the present invention is to provide a unidirectional reinforcing fiber sheet that is excellent in a reinforcing effect and has little decrease in strength utilization rate even when the amount of reinforcing fibers used is increased.

The present invention can solve the above problems,
[1] A fiber reinforced sheet in which a plurality of units are arranged in one direction with a fiber group composed of reinforcing fibers as a unit, the fiber group is a reinforcing fiber group formed by twisting reinforcing fibers, and the fiber sheet On the front and back surfaces, covering auxiliary fibers intersecting with the reinforcing fiber groups are arranged in the length direction of the reinforcing fiber groups, and the covering auxiliary fibers are bound by the entanglement auxiliary fibers to form a bag-like warp knitted structure. A reinforcing fiber sheet, wherein the reinforcing fiber group is inserted into the bag-like warp knitted structure in multiple stages.
[2] In the reinforcing fiber group, the reinforcing fiber is a reinforcing fiber sheet according to [1], wherein the reinforcing fiber is twisted together with a twist coefficient K of 2000 to 7000,
However, K = T × (DT) ^1/2
T: Number of twists (times / m)
DT: Total fineness of twisted yarn (dtex)
[3] The reinforcing fiber sheet according to [1] or [2], wherein the arrangement density of the reinforcing fiber group is 20 to 200 / 2.54 cm.
[4] The reinforcing fiber sheet according to any one of [1] to [3] above, wherein the weft knitted fabric has a weft density of 10 to 150 courses / 2.54 cm per side,
[5] The reinforcing fiber sheet according to any one of [1] to [4], wherein the fineness of the auxiliary fiber is 200 dtex or less,
[6] The reinforcing fiber sheet according to any one of [1] to [5] above, wherein the auxiliary fiber has an initial tensile resistance of 10 to 200 cN / dtex.
[7] The reinforcing fiber sheet according to any one of [1] to [6], wherein the auxiliary fiber is a polyolefin fiber,
[8] The reinforcing fiber sheet according to any one of [1] to [7], wherein the tensile strength of the reinforcing fiber is 15 to 60 cN / dtex or more,
[9] The reinforcing fiber sheet according to any one of [1] to [8], wherein the reinforcing fiber group has a fineness of 1000 to 50000 dtex, and [10] the preceding item [1], in which the reinforcing fiber is an aromatic polyamide fiber. -It is related with the reinforcing fiber sheet of any one of [10].

The reinforcing fiber sheet of the present invention is a reinforcing fiber sheet that is excellent in reinforcing effect and excellent in form stability and flexibility required at the time of work, and is used to reinforce structures such as buildings and molded bodies such as pipes. Particularly suitable for reinforcement of resin pipes for fluid transportation such as oil pipelines, water pipes, sewage pipes, gas pipes and the like.
That is, in the fiber reinforced sheet of the present invention, since the reinforcing fiber group is inserted in multiple stages, the strength utilization rate of the reinforcing fiber is high and the strength per knitting width is large.
Of the fiber reinforced sheets of the present invention, the embodiment in which the reinforcing fibers are twisted together with a twisting coefficient K = 2000 to 7000 is particularly excellent in the shape retention of the reinforcing fiber group.
Of the fiber reinforced sheets of the present invention, the aspect in which the auxiliary fiber has an initial tensile resistance value of 10 to 200 cN / dtex also has an effect of preventing curling of the ear portion of the reinforced fiber sheet.
Of the fiber reinforced sheets of the present invention, the embodiment in which the coating auxiliary fiber is a polyolefin fiber is particularly suitable for reinforcing a polyolefin resin pipe.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an enlarged partial schematic view showing an example of a reinforcing fiber sheet of the present invention, where (A) is a front surface and (B) is a back surface. 1 is a reinforcing fiber group, 2 is a covering auxiliary fiber, and 3 is an entanglement auxiliary fiber.

  In the reinforcing fiber sheet of FIG. 1, a plurality of reinforcing fiber groups (1) are arranged in one direction. The reinforcing fiber group is a fiber group made of reinforcing fibers. In the present invention, a reinforcing fiber group formed by twisting reinforcing fibers is defined as one unit, that is, one reinforcing fiber group.

The reason why the reinforcing fibers are twisted together in the reinforcing fiber group is to maintain the form of the reinforcing fiber group so that the reinforcing fibers are not scattered in the reinforcing fiber group. However, if twisted too strongly, there is a tendency to cause problems such as a decrease in strength and difficulty in handling the yarn due to twisting torque. Therefore, a low twist is preferable. Specifically, it is preferable that the twisting coefficient K represented by the following formula is 2000 to 7000 with the reinforcing fiber group as one twisted yarn.
K = T × (DT) ^1/2
In the above formula, T represents the number of twists (times / m), and DT represents the total fineness (dtex) of the twisted yarn.

  As shown in FIG. 1, on the front surface (A) of the reinforcing fiber sheet of the present invention, the covering auxiliary fiber (2) intersecting with the reinforcing fiber group (1) is arranged in the length direction of the reinforcing fiber group. Has been. As is apparent from FIG. 1, the fact that the covering auxiliary fiber intersects with the reinforcing fiber group means that the covering auxiliary fiber is swung from side to side across the center line of the reinforcing fiber group. Is arranged in the length direction of the reinforcing fiber group while being reversed by being swung left and right.

  Similarly, also on the back surface (B) of the reinforcing fiber sheet shown in FIG. 1, the covering auxiliary fiber (2) intersecting the reinforcing fiber group (1) is arranged in the length direction of the reinforcing fiber group.

  In FIG. 1, between the reinforcing fiber groups, the covering auxiliary fiber (2) arranged on the front surface (A) and another covering auxiliary fiber (2) arranged on the back surface (B), The bag-like warp knitted structure is formed by binding with the tangled auxiliary fibers (3). The reinforcing fiber group (1) is warped and inserted into the bag-like warp knitted structure, and the reinforcing fiber sheet of the present invention is configured. With this configuration, the reinforcing fiber group is held in the bag-like warp knitted structure made of the coating auxiliary fiber to prevent misalignment, so that the form stability as the reinforcing fiber sheet can be obtained. In addition, the reinforcing fiber group is regularly arranged in parallel in one direction, and the resin can be easily impregnated between the reinforcing fibers.

  In the reinforcing fiber sheet of the present invention, it is important that the reinforcing fiber group is inserted through multiple stages with respect to the insertion. FIG. 1 is a plan view of the front surface (A) and the back surface (B), and it is assumed that the fiber groups inserted in multiple stages are regularly stacked in the thickness direction of the reinforcing fiber sheet. It is not possible to represent the state of multi-stage insertion.

  Therefore, multi-stage insertion will be described with reference to FIG. FIG. 2 is an enlarged partial schematic view seen from a cross section perpendicular to the arrangement direction of the reinforcing fiber groups in the reinforcing fiber sheet of FIG. 1, and (a) shows a case where the reinforcing fiber groups are inserted in two stages (b) ) Shows the case where the reinforcing fiber groups are inserted in three stages, but the number of stages in which the reinforcing fiber groups are inserted in multiple stages may be multistage, that is, two or more stages, and is not particularly limited. The greater the number of stages, the greater the amount of reinforcing fibers used. On the other hand, the greater the number of stages, the higher the risk that the stacked stages will collapse. Considering such factors, the number of stages for multi-stage insertion is preferably 2 to 5 stages, more preferably 2 to 3 stages. However, the reinforcing fiber group inserted in multiple stages does not necessarily have to be stacked in an orderly manner without collapsing, and some collapse may be allowed.

  In the present invention, it is very advantageous to insert reinforcing fiber groups in multiple stages as described above in order to increase the amount of reinforcing fibers used and enhance the reinforcing effect. For example, it is easier to increase the strength utilization rate of the reinforcing fibers by inserting n stages of reinforcing fiber groups having a fineness d / n (n is a natural number) than when inserting reinforcing fiber groups having a certain fineness d one by one. This is because the process passability tends to decrease as the fineness per reinforcing fiber group increases more than a certain level, and is rubbed at the bent portions of guides, wrinkles, needles, etc. during the manufacture of the reinforcing fiber sheet. This is because a yarn length difference is likely to occur between single yarns. In addition, as a strength utilization factor of a reinforcing fiber, 85% or more is preferable and 90% or more is more preferable.

  The reinforcing fiber sheet of the present invention having such a configuration can be manufactured by improving a general Russell warp knitting. Formation of the warp knitting structure of the covering auxiliary fiber and the entanglement auxiliary fiber is performed, for example, according to “Knowledge of new fiber” (published by Kamakura Shobo, revised third edition of 1994, P104 to P107). For example, the reinforcing fiber sheet of FIG. 1 is formed by knitting auxiliary fibers (3) covering auxiliary fibers (2), multistage reinforcing fiber groups (1) and covering auxiliary fibers (2) as a creel to a warp knitting machine. It is manufactured by supplying to a Raschel warp knitting machine.

  The weft-direction density in the bag-shaped warp knitted structure composed of the above-described covering auxiliary fibers and entanglement auxiliary fibers, that is, the number of courses per 2.54 cm of the covering reinforcing fibers is preferably 10 to 150 courses per side. 60 courses are more preferable. Setting the number of courses per 2.54 cm to 10 courses or more per side is preferable in that the form is stable and the sheet is easy to handle, and the reinforcing fiber group is easily aligned in the warp direction and the strength utilization rate is increased. On the other hand, it is preferable to set the number of courses per 2.54 cm to 150 courses or less per side. If the number of courses exceeds 150 courses, the reinforcing fiber group is more strongly held than necessary and difficult to move, and the entire reinforcing fiber sheet becomes hard. This is because there is a tendency.

  The arrangement density of the reinforcing fiber group in the reinforcing fiber sheet of the present invention is not particularly limited, and may be appropriately set in consideration of the reinforcing effect, resin impregnation property, etc., depending on the fineness of the reinforcing fiber group, 20-200 / 2.54 cm is preferable, and 40-100 / 2.54 cm is more preferable. If you want to make the reinforcing fiber sheet thinner or if you want to improve the knitting, it is advantageous to set the arrangement density of the reinforcing fiber group smaller, and if you want to increase the form stability and strength per sheet width It is advantageous to set the arrangement density of the reinforcing fiber groups to be large. In addition, as the arrangement density per step in the multi-stage insertion, 10 to 50 pieces / 2.54 cm is preferable, and 15 to 40 pieces / 2.54 cm is more preferable.

  Further, the fineness per one (one unit) reinforcing fiber group is preferably 1000 to 20000 dtex, and more preferably 3000 to 15000 dtex. Setting it to 1000 dtex or more is preferable for securing the form stability and strength, but it is preferable not to excessively increase the fineness in order to maintain the above-described process passability and maintain the strength utilization rate of the reinforcing fiber.

  Although it does not specifically limit as a reinforcing fiber which comprises a reinforcing fiber group, The fiber whose tensile strength in a raw yarn is 15 cN / dtex-60 cN / dtex is preferable. Specific examples of the reinforcing fiber include polyethylene fiber, carbon fiber, glass fiber, aromatic polyamide fiber, etc. Among them, carbon fiber and aromatic polyamide fiber are preferable, and aromatic polyamide fiber is excellent in flexibility. Of these, polyparaphenylene terephthalamide fibers are particularly preferred because of their high strength. Polyparaphenylene terephthalamide fibers are available as commercial products such as “Kevlar (registered trademark) 29” manufactured by Toray DuPont Co., Ltd.

  The single fiber filament fineness of the single reinforcing fiber of the reinforcing fiber is not particularly limited, but is preferably 0.1 dtex to 3 dtex, and particularly preferably 1 dtex to 2 dtex. As the single fiber filament fineness increases, the bending hardness generally increases and the sheet tends to become stiffer.

The basis weight of the reinforcing fiber sheet of the present invention is not particularly limited, and varies depending on the fineness and arrangement density of the reinforcing fiber group, but is preferably 300 to 2000 g / m ² , and 500 to 1500 g / m ^2. Is more preferable.

  Further, as the covering auxiliary fiber and the entanglement auxiliary fiber (these may be simply referred to as “auxiliary fiber” collectively), it is possible to use a fiber having low rigidity within a range in which the form stability as the reinforcing fiber sheet can be secured. preferable. This is because when the stiff fibers are used as auxiliary fibers, the ears of the reinforcing fiber sheet tend to curl easily, and when the sheet is stressed, the reinforcing fibers tend to crimp. Because it is in. Furthermore, by using auxiliary fibers with low rigidity, the reinforcing fiber sheet becomes a flexible sheet with low bending hardness, so that it is easy to handle when used for construction, etc., and obtain a reinforcing fiber sheet with excellent workability Can do. For this reason, the fineness of the auxiliary fiber is preferably 250 dtex or less, more preferably 15 to 180 dtex, and particularly preferably 20 to 100 dtex. For the same reason, the initial tensile resistance of the auxiliary fiber is preferably 15 to 200 cN / dtex, more preferably 20 to 150 cN / dtex, and particularly preferably 25 to 100 cN / dtex. Here, the initial tensile resistance refers to the initial tensile resistance (Young's modulus) measured according to JIS L1013 8.19 Item 1 B method.

  In addition, the reinforcing fiber (group) substantially contributes to the reinforcing effect, which is the purpose of use of the reinforcing fiber sheet, and the auxiliary fiber cannot be expected to substantially contribute to the reinforcing effect. In some cases, it is preferable that the fiber shape is no longer retained after the material is fixed to the object to be reinforced. For example, when coating a thermoplastic resin layer from the outside of the reinforcing fiber sheet and performing heat processing, it is better to allow the auxiliary fibers to move to some extent without restraining the reinforcing fiber groups, and thus the reinforcing fiber sheet and hence the object to be reinforced In some cases, the flexibility of the reinforcing fiber group is eliminated, and after the thermal processing, crimps and defects of the reinforcing fiber group disappear and the strength and elastic modulus of the reinforcing fiber sheet are increased.

  As described above, when the reinforcing fiber sheet is melt-impregnated with a thermoplastic resin as a matrix resin, it is preferable that the auxiliary fiber has a melting point equal to or lower than the melting point of the matrix resin. It can be melted and incorporated into the matrix resin.

  Specifically, considering the case where it is desired to melt the auxiliary fiber, the melting point of the auxiliary fiber is preferably 260 ° C. or less, more preferably 190 to 210 ° C., and particularly preferably 130 to 190 ° C. When the polyolefin resin is melt-impregnated in the use of the fiber reinforced sheet of the present invention, the melting point of the auxiliary fiber is preferably 190 ° C. or lower.

  From the viewpoint of the material constituting the auxiliary fiber, it is not particularly limited, and can be appropriately selected from natural fiber, semi-synthetic fiber, and synthetic fiber. Synthetic fiber is preferable, among which polyolefin fiber and polyvinyl alcohol. Of these, polyester fibers and polyester fibers are preferred.

  In particular, when the reinforcing fiber sheet of the present invention is used for molding oil, natural gas or other liquid or gas transport pipes, polyolefin resins are often used for these pipes. Based fibers are particularly preferred, and polyethylene fibers are particularly preferred. The fiber-reinforced resin pipe obtained by molding using the reinforcing fiber sheet and polyolefin resin of the present invention is lighter and more workable and transportable than a steel pipe, and is flexible and workable. It has the advantages of being excellent in resistance, resistant to shocks such as earthquakes, and having excellent corrosion resistance, so it is increasingly promising as a liquid or gas transport pipe as described above.

  The reinforcing fiber sheet of the present invention configured as described above has high-strength reinforcing fibers arranged in a stable manner while maintaining parallelism by a bag-like warp knitted structure formed of auxiliary fibers. There are few, and it is soft enough to bend during work. In addition, by inserting the reinforcing fiber group in multiple stages, the reinforcing fiber can be used in a larger amount without greatly reducing the strength utilization rate of the reinforcing fiber, thereby greatly enhancing the reinforcing effect. Therefore, the reinforcing fiber sheet of the present invention is useful not only for reinforcing the pipes described above, but also for reinforcing elevated bridges and floors, building columns and walls, etc. Since it has high tensile strength and shear strength, it is a high industrial value that cannot be found in other materials as a reinforcing member.

  Furthermore, since the reinforcing fiber sheet of the present invention can be easily impregnated with a resin, in particular, if used by impregnating the resin, not only for reinforcing the above-described pipe, but also including general structures, It is ideal for reinforcing materials such as elevated bridges, floor boards, building columns, and walls.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example. The characteristics described in the examples were measured or evaluated by the following methods.
1. Number of twists (times / m):
It measured according to description of the twist number term of JIS (1999) L1013 8.13.1.
2. Arrangement density of reinforcing fiber group (lines / 2.54 cm):
Reinforcing fiber groups with a sheet width of 3 cm were extracted and the number (unit number) was measured and converted to the number per 2.54 cm.
3. Weft density of bag-like warp knitting structure (course / 2.54 cm):
The density described in Section 8.8 of JIS (1999) L1018 was followed.
4). Fineness (dtex):
JIS (1999) L1013 B method was followed.
5. Initial tensile resistance (cN / dtex):
JIS (1999) L1013 8.19.1 Section B method was followed.
6). Tensile strength (cN / dtex):
According to JIS (1999) L1013 8.5.1.
7). Sheet tensile strength (N / 2.54 cm):
JIS (1999) L1018 Section 8.13 The cut strip method was followed. In addition, the value measured using the test piece of 30 mm width was converted into the strength per 2.54 cm width.
8). Strength utilization rate of reinforcing fiber (%):
The strength S ₀ of the reinforcing fiber in the raw yarn, the tensile strength L ₁ of the sheet (N / 30 mm), and the total fineness D (dtex) of the reinforcing fiber in the width of 30 mm of the sheet were measured and calculated according to the following formula. .
Formula: [Intensity utilization rate (%)] = {(L ₁ / D) / S ₀ } × 100

9. Curl property:
The curling property of the knitted fabric was sensoryly evaluated based on the following criteria, assuming that the less the curling, the better.
Very good ◎
Good ○ Somewhat bad △
Bad ×
10. Resin impregnation:
It was attached to the sheet using a 3: 1 mixture of epoxy resin (Cemedine, # 1500) and amine curing agent. The amount of adhesion was 10% by mass relative to the mass of the sheet before adhesion. After the resin was cured, the bending hardness of the sheet was sensuously examined, and the higher the bending hardness, the better the impregnation property was evaluated according to the following criteria.
Very good ◎
Good ○ Somewhat bad △
Bad ×
11. Sheet handling:
Sensory evaluation was performed on the bending softness and the winding property.
Very good ◎
Good ○ Somewhat bad △
Bad ×
12 Comprehensive evaluation:
The sheet was evaluated comprehensively from the characteristic value of the sheet, the resin impregnation property, the sheet handling property and the knitting property.
Very good ◎
Good ○ Somewhat bad △
Bad ×

[Example 1]
As the reinforcing fiber group, polyparaphenylene terephthalamide fiber (“Kevlar” (registered trademark) 29 ”fineness 4900 dtex (single fiber filament fineness 1.6 dtex, strength 18.9 cN / dtex) manufactured by Toray DuPont Co., Ltd.) The one subjected to S twist 57 times / m was used as one unit of the reinforcing fiber group so that the total fineness of the second stage was 9800 dtex by the two-stage insertion. Polyethylene terephthalate fibers (“Tetron” (registered trademark) manufactured by Toray Industries, Inc.) having a fineness of 84 dtex / 24 single fiber filaments were used as pressing threads for the front and back surfaces.
As the entanglement auxiliary fiber, a polyethylene terephthalate fiber (“Tetron” (registered trademark) manufactured by Toray Industries, Inc.) having a fineness of 56 dtex / twelve single filament filaments is used to entangle the front and back pressing threads. Using.
The above-mentioned covering auxiliary fiber, auxiliary fiber and reinforcing fiber group are supplied to a Russell warp knitting machine so that the reinforcing fiber group is a two-stage warp insertion, to constitute a bag-like warp knitting structure shown in FIG. A reinforcing fiber sheet having the characteristics shown in Table 1 was obtained.
The design conditions for the warp knitting structure were a wale (W / 25 mm) of 28.0, a course (C / 2.54 cm) of 20, and a heel 5.

[Example 2]
As a reinforcing fiber group, a polyparaphenylene terephthalamide fiber (“Kevlar” (registered trademark) 29 ”manufactured by Toray DuPont Co., Ltd.) having a fineness of 3300 dtex (single fiber filament fineness of 1.6 dtex, strength of 18.9 cN / dtex) The one obtained by applying S twist 71 times / m to the object as one unit of the reinforcing fiber group, and using the three-stage insertion, so that the total fineness of the three stages is 9900 dtex, and the covering auxiliary fiber, The bag-like warp knitting structure shown in FIG. 1 is the same as in Example 1 except that the auxiliary fiber and the reinforcing fiber group are supplied to the Russell warp knitting machine so that the reinforcing fiber group has a three-stage warp insertion. A reinforcing fiber sheet having the characteristics shown in Table 1 was obtained.

[Example 3]
In this example, polyethylene fibers are used as the coating auxiliary fibers.
As the coating auxiliary fiber, except that polyethylene fiber (Toyobo Co., Ltd., “Dyneema” (registered trademark) ”having 56 dtex / number of single filament filaments of 12 was used, A bag-like warp knitted structure shown in FIG. 1 was formed, and a reinforcing fiber sheet having the characteristics shown in Table 1 was obtained.

[Comparative Example 1]
This is a comparative example in which a reinforcing fiber group corresponding to the prior art is inserted in one unit as one stage.
As a reinforcing fiber group, a polyparaphenylene terephthalamide fiber (“Kevlar” (registered trademark) 29 ”manufactured by Toray DuPont Co., Ltd.) having a fineness of 9900 dtex (single fiber filament fineness of 1.6 dtex, strength of 18.9 cN / dtex) The one with S twist of 40 times / m is used as one unit of the reinforcing fiber group, and it is used in the one-stage insertion through insertion, the covering auxiliary fiber, the auxiliary fiber, and the reinforcing fiber group, and the reinforcing fiber group has one stage. The bag-shaped warp knitting structure shown in FIG. 1 was constructed in the same manner as in Example 1 except that it was supplied to the Russell warp knitting machine so as to be warp insertion and that the design conditions were set to 筬 4. A reinforcing fiber sheet having the characteristics shown in Table 1 was obtained.

[Examples 4 and 5]
It is the Example which changed the number of twists in a reinforcement fiber group.
Except that the number of twists in one unit of the reinforcing fiber group was S twist 25 times / m (Example 4) or S twist 140 times / m (Example 5), the same procedure as in Example 2 was performed. 1 was obtained, and a reinforcing fiber sheet having the characteristics shown in Table 1 was obtained.

  Table 1 shows the characteristics of the reinforcing fiber sheets of the examples and comparative examples.

As the results in Table 1 show, the reinforcing fiber sheets of Examples 1 and 2 both have favorable characteristics. In particular, the strength utilization rate became a preferable value exceeding 85% by inserting the reinforcing fiber group in multiple stages. This is because thin reinforcing fiber groups can be used by inserting in multiple stages, so that single fiber filament yarns can be easily aligned at bent portions such as guides and wrinkles, and the strength utilization rate can be increased, and the length of the yarn between the single fiber filament yarns can be increased. This is because the difference is less likely to occur, so there is little thread breakage or supply tension fluctuation and excellent process passability.
In Example 3, polyethylene fiber is used as the coating auxiliary fiber, but the curling property of the knitted fabric is small, and it is preferably used because the melting point is almost the same and the compatibility is good for reinforcing the polyethylene pipe. be able to.
The reinforcing fiber sheets of Examples 4 and 5 are obtained by changing the number of twists of the reinforcing fiber. However, both Example 4 in which the twisting coefficient is small and Example 5 in which the twisting coefficient is large tend to decrease the strength utilization rate. It can be seen that Examples 1 to 3 are more preferable.

It is an expansion partial schematic diagram of an example of the reinforcing fiber sheet of the present invention, (A) is a front side, and (B) is a back side. It is an expansion partial schematic diagram (sectional drawing) which illustrates the insertion form of the reinforcement fiber group in the fiber reinforcement sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reinforcing fiber group 2 Covering auxiliary fiber 3 Tangle covering auxiliary fiber

Claims (10)

  In the fiber reinforced sheet in which a plurality of units are arranged in one direction, the fiber group is a reinforced fiber group formed by twisting reinforcing fibers, and the front and back surfaces of the fiber sheet. The covering auxiliary fibers intersecting each reinforcing fiber group are arranged in the length direction of each reinforcing fiber group, and the covering auxiliary fibers are bound by the entanglement auxiliary fibers to form a bag-like warp knitted structure. The reinforcing fiber sheet is characterized in that the reinforcing fiber group is warped and inserted into the bag-like warp knitted structure in multiple stages. The reinforcing fiber sheet according to claim 1, wherein in the reinforcing fiber group, the reinforcing fibers are twisted together with a twist coefficient K of 2000 to 7000.
However, K = T × (DT) ^1/2
T: Number of twists (times / m)
DT: Total fineness of twisted yarn (dtex)   The reinforcing fiber sheet according to claim 1 or 2, wherein the reinforcing fiber group has an arrangement density of 20 to 200 fibers / 2.54 cm.   The reinforcing fiber sheet according to any one of claims 1 to 3, wherein the weft-direction density of the bag-like warp knitted structure is 10 to 150 courses / 2.54 cm per side.   The reinforcing fiber sheet according to any one of claims 1 to 4, wherein the fineness of the auxiliary fiber is 200 dtex or less.   The reinforcing fiber sheet according to any one of claims 1 to 5, wherein the auxiliary fiber has an initial tensile resistance of 10 to 200 cN / dtex.   The auxiliary fiber is a polyolefin fiber, The reinforcing fiber sheet according to any one of claims 1 to 6.   The reinforcing fiber sheet according to any one of claims 1 to 7, wherein the reinforcing fiber has a tensile strength of 15 to 60 cN / dtex or more.   The reinforcing fiber sheet according to any one of claims 1 to 8, wherein the reinforcing fiber group has a fineness of 1000 to 50000 dtex. The reinforcing fiber sheet according to any one of claims 1 to 9, wherein the reinforcing fiber is an aromatic polyamide fiber.

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