JP2019135337A - Wholly aromatic polyamide fiber - Google Patents

Abstract

To provide a fiber for reinforcing a concrete composition, which has rust prevention, high strength, a high elastic modulus, and excellent sizeability.SOLUTION: In a wholly polyamide fiber, a shape of a cross section satisfies the following requirements a) and b): a) a shape of cross section in the fiber has 2 or more and 12 or less concave portions; and b) in the cross section, flatness, a degree of multi-lobe, and concavity respectively shown by the following formula (1)-(3) are satisfied: flatness (A/B)=1.5-3.0...(1); a degree of multi-lobe (C/B)=0.4-0.8...(2); and concavity (D/E)=0.2-4.5...(3), wherein: the maximum value in a length of a long side of the cross section is A; the maximum value in a length of a short side thereof is B; the length of the shortest line segment is C among two line segments by which the bottom surfaces of concave portions adjacent to B are connected; the length between contact points of tangent lines is D, the tangent lines being drawn respectively on 2 convex parts that are formed on both sides of the concave part; and the length of a perpendicular line drawn from the center of the tangent line, to the contact point of the concave part, is E.SELECTED DRAWING: Figure 1

Description

  The present invention relates to wholly aromatic polyamide fibers suitable for reinforcement of concrete or mortar moldings. More specifically, the present invention has a specific cross-sectional shape to enable strength or durability of concrete or mortar moldings. The present invention relates to wholly aromatic polyamide fibers that can be improved as much as possible.

  Concrete or mortar moldings are widely used for building materials and civil engineering because they are excellent in compressive strength, nonflammability and durability. However, since concrete is a low toughness material with low tensile strength and low fracture strain, when concrete breaks due to earthquakes, etc. in tunnels and bridges, the time it takes for these structures to collapse is short. There was a problem that the time to evacuate to the outside of the tunnel or the bridge was limited when it was damaged in the middle of the bridge or the bridge.

  For this reason, for concrete used for tunnels, bridges, etc., a method is used in which fibers are kneaded into concrete to improve toughness as a concrete composition. That is, by kneading the fibers in the concrete, the fibers are pulled out after the fracture of the concrete, and the toughness of the concrete composition is improved.

  Examples of fibers used at this time include steel fibers, organic fibers, and carbon fibers. When steel fibers are used, if cracks are generated on the surface of the concrete due to drying shrinkage or the like, rust along the steel fibers proceeds centering on the cracks, and the deterioration of the concrete progresses, resulting in insufficient durability.

  In addition, in coastal concrete compositions affected by seawater, chlorine ions in seawater penetrate into the concrete and promote the generation of rust on the steel fiber, reducing the strength of the steel fiber and reducing the reinforcing effect. The problem of end up occurs.

On the other hand, when organic fibers are used, the occurrence of rust like steel fibers can be prevented, but the strength and elastic modulus of the organic fibers themselves are low, so that there is a problem that sufficient strength cannot be expressed when a load is applied to concrete. is there. (Patent Document 1)
Further, if the fiber bundles are scattered in the concrete, the single fiber breaks, so that the reinforcing effect at the time of drawing decreases. In order to solve this, a method of applying oil to the surface of the fiber bundle has been proposed. In this method, the convergence is improved, but the adhesion between the fiber and the concrete is reduced by the oil adhering to the surface. The reinforcing effect cannot be fully exhibited.

  Furthermore, when carbon fiber is used, it is thought that it is useful for improving the strength of concrete composition because it can prevent the occurrence of rust like steel fiber and has higher strength and elastic modulus than organic fiber. In this case, when carbon fiber is kneaded with concrete, the fiber is broken by the shearing force of the mixer, and a sufficient fiber length cannot be maintained, so that there is a problem that sufficient strength cannot be achieved.

  In view of the above situation, a concrete composition that does not generate rust in concrete, has sufficient strength and elastic modulus, has excellent fiber bundle focusing properties, and does not break when kneaded with concrete. Reinforcing fibers are eagerly desired.

JP 2005-323360 A

    The problem of the present invention is to solve the problems in the prior art, there is no occurrence of rust in the concrete, it has sufficient strength and elastic modulus, has excellent convergence as a fiber bundle, and An object of the present invention is to provide a fiber for reinforcing a concrete composition that does not cause breakage during kneading.

As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by using wholly aromatic polyamide fibers having a specific cross-sectional shape. That is, the present invention is a wholly aromatic polyamide fiber, which is mainly composed of wholly aromatic polyamide, and whose cross-sectional shape satisfies the following requirements a) and b) simultaneously:
a) The cross-sectional shape of the fiber has 2 to 12 recesses.
b) In the fiber cross section, the maximum value of the length of the long side is A, the maximum value of the short side length is B, and the long of the two sets of line segments connecting the bottom surfaces of the recesses adjacent to B The length of the shorter line segment is C, a tangent line is drawn between the two convex portions formed on both sides of the concave portion, the length between the contact points is D, and a perpendicular line descending from the center of the tangent line, When the length to the contact point with the concave portion is represented by E, the flatness, irregularity, and concave values represented by the following formulas (1) to (3) are satisfied.
Flatness (A / B) = 1.5 to 3.0 (1)
Deformity (C / B) = 0.4 to 0.8 (2)
Concaveness (D / E) = 0.2 to 4.5 (3)
as well as,
A concrete or mortar composition reinforced by the wholly aromatic polyamide fiber.

  According to the present invention, there is no occurrence of rust in concrete, it has sufficient strength and elastic modulus, has excellent fiber bundle focusing properties, and does not break when kneaded with concrete. A reinforcing fiber can be obtained.

The schematic diagram which shows an example of the cross-sectional shape of the wholly aromatic polyamide fiber of this invention.

    Hereinafter, the present invention will be described in detail.

<Totally aromatic polyamide fiber>
The wholly aromatic polyamide used in the present invention is a polymer in which one or more divalent aromatic groups are linked by an amide bond. Two or more aromatic rings may be present in the aromatic group, and the aromatic rings may be directly bonded or may be bonded through oxygen or sulfur. The hydrogen atom of the divalent aromatic group may be substituted with a halogen molecule, a lower alkyl group, or a phenyl group.

  The wholly aromatic polyamide fiber used in the present invention can be obtained by reacting an aromatic dicarboxylic acid dichloride component and an aromatic diamine component in a solution in an amide polar solvent. As the aromatic dicarboxylic acid chloride component used in the production of the wholly aromatic polyamide, generally known compounds can be used. From the viewpoint of the obtained fiber properties, terephthalic acid chloride is preferred.

  The aromatic diamine component used in the production of the wholly aromatic polyamide is not particularly limited, and generally known ones can be used. From the viewpoint of the obtained fiber properties, it is preferable to use a combination of p-phenylenediamine and 3,4'-diaminodiphenyl ether. The ratio of the aromatic dicarboxylic acid chloride component to the aromatic diamine component is preferably in the range of 0.90 to 1.10 as the molar ratio of the aromatic dicarboxylic acid chloride component to the aromatic diamine component, 0.95 More preferably, it is in the range of ˜1.05. If the molar ratio of the aromatic dicarboxylic acid chloride component is out of this range, the reaction with the aromatic diamine component does not proceed sufficiently and a high degree of polymerization cannot be obtained, which is not preferable.

  As the solvent for polymerization, N-methyl-2-pyrrolidone that dissolves the product wholly aromatic polyamide well in the amide polar solvent is most preferable. After completion of the reaction, a basic inorganic compound may be added to neutralize hydrochloric acid in the system. The solution of the wholly aromatic polyamide thus produced is discharged from the spinneret using a semi-dry semi-wet spinning method.

  An aromatic polyamide fiber having a specific cross-sectional shape can be obtained by discharging a solution of wholly aromatic polyamide from a die having a discharge hole shape similar to the cross-sectional shape of the fiber and coagulating with a coagulating liquid.

  Then, the wholly aromatic polyamide solution discharged from the mouthpiece is deposited on the coagulating liquid through the air gap and coagulated. At this time, in order to increase the degree of irregularity of the fiber, it is preferable that the time from discharge to landing on the coagulating liquid is short. Therefore, the air gap is preferably short. However, if the air gap is too short, the coagulating liquid adheres to the die when the coagulating liquid surface is shaken, resulting in ejection failure. Therefore, the air gap length is preferably 5 mm or more and 30 mm or less. The composition of the coagulation liquid needs to be a poor solvent for wholly aromatic polyamide such as water, but does not need to be a simple substance, and may be a mixed solution of NMP and water, for example. The higher the coagulation rate, the higher the degree of profile, and therefore the higher the temperature of the coagulation liquid is preferred. The temperature is preferably higher than 30 ° C, more preferably higher than 60 ° C. However, if the temperature is too high, the vaporized coagulating liquid will condense on the discharge surface of the die and cause a discharge failure, so 100 ° C. or less is appropriate.

  After pulling up the coagulated yarn from the coagulation liquid, a final wholly aromatic polyamide fiber can be obtained by a known method. For example, the solvent is removed from the undrawn yarn formed by carrying out the water washing step, the drawing is carried out as necessary, and the final fiber is oriented by drawing as necessary after passing through the drying step and the like. Can be obtained.

  The fibers of the present invention are preferably stretch-oriented. The drawing method is not particularly limited, and may be any of not only washing drawing in a coagulated yarn state and boiling water drawing but also heating drawing in a dry yarn state. Moreover, there is no restriction | limiting in particular about a draw ratio, However, It is preferable that it is 5 times or more, and it is further more preferable that it is 8 times or more. By controlling the draw ratio, the elongation and strength of the resulting fully aromatic polyamide fiber can be controlled. The stretching temperature is preferably carried out at a temperature of the glass transition temperature of the wholly aromatic polyamide + 100 ° C. or less.

  The method for impregnating the wholly aromatic aramid fiber with the adhesive to improve the adhesion with the concrete or mortar composition is not particularly limited, but specifically, the adhesive is sprayed on the running yarn. And a method of immersing the thread in a bath containing an adhesive, a method of bringing the thread into contact with a roller to which the adhesive is attached, etc. It doesn't matter. The adhesive is heated after being impregnated to evaporate moisture and harden it, whereby a fiber material with good convergence and rigidity can be produced.

<Fiber cross-sectional shape>
Regarding the cross-sectional shape of the wholly aromatic aramid fiber of the present invention, the adhesiveness to the concrete and the mortar composition is improved by simultaneously satisfying the following requirements a) and b), and the impregnation with a bundling resin or an adhesive. As a result, the Gurley hardness, which is an index of the rigidity of the fiber bundle, becomes larger than that of the round cross section.

  That is, FIG. 1 is a schematic diagram showing an example of the cross-sectional shape of the wholly aromatic polyamide fiber of the present invention, wherein A is the maximum value of the long side length, B is the maximum value of the short side length, and C is Of the two sets of line segments connecting the bottom surfaces of the recesses adjacent to B, the length of the shorter line segment, D is tangent to the two protrusions formed on both sides of the recess, The length between the contact points, and E, represent the lengths of the perpendicular lines dropped from the center of the tangent line to the contact points with the recesses.

Here, in the present application,
a) The cross-sectional shape of the fiber has 2 to 12 recesses,
b) satisfying the values of flatness, irregularity and concaveness represented by the following formulas (1) to (3);
Flatness (A / B) = 1.5 to 3.0 (1)
Deformity (C / B) = 0.4 to 0.8 (2)
Concaveness (D / E) = 0.2 to 4.5 (3)
It is important. When the cross-sectional shape of the fiber does not satisfy the requirements a) and b), the reinforcing effect on the concrete or mortar composition is not sufficiently exhibited.

<Number of recesses>
When the number of concave portions in the fiber cross section is large, the surface area with respect to the cross-sectional area is increased, so that the impregnation property of the focusing resin is improved, and the rigidity of the fiber bundle is improved. However, if there are too many recesses, the interval between the recesses becomes narrow and the focusing resin does not easily enter the fiber surface, so that the rigidity of the fiber bundle decreases. On the other hand, when the number of recesses is too small, the surface area with respect to the cross-sectional area approaches a round cross section, so that the impregnating property of the focusing resin approaches that of a round cross section. Therefore, the rigidity improvement of a fiber bundle is not seen. For these reasons, the number of recesses is required to be 2 or more and 12 or less. A preferable range of the number of recesses is 3 or more and 12 or less.

  When the flatness (A / B) is smaller than 1.5, the bending rigidity of the fiber bundle is lowered and the Gurley hardness is lowered, which is not preferable. On the other hand, when the flatness (A / B) is larger than 3.0, the strength of the fiber itself is lowered, which is not preferable. If the degree of irregularity (C / B) is less than 0.4, the cross-sectional shape approaches a round cross section, and the impregnation property of the adhesive deteriorates. On the other hand, when the degree of profile (C / B) is larger than 0.8, the strength of the fiber itself is lowered, and it becomes difficult to exhibit the reinforcing performance when kneaded into concrete, which is not preferable. When the concave degree (D / E) is smaller than 0.2, the concrete cannot enter the concave portion of the fiber bundle, and the convergence property of the fiber bundle is lowered, which is not preferable. On the other hand, when the concave degree (D / E) is larger than 4.5, it is advantageous for the concrete to enter between the concave parts, but the strength of the fiber itself is lowered, so that the concrete reinforcing performance by the fiber bundle is sufficiently developed. Since it becomes difficult, it is not preferable.

<Single fiber fineness>
If the single fiber fineness is too small, the strength of the single fiber is lowered, and therefore, when kneaded with concrete, the single yarn breakage is caused by the shearing force of the mixer, and the reinforcing effect on the concrete is lowered, which is not preferable. On the other hand, if the single fiber fineness is too large, the impregnation property of the adhesive is deteriorated and the convergence property is lowered. For these reasons, the single fiber fineness is preferably in the range of 1.6 to 7.0 dtex.

<Tensile strength>
When the strength and elastic modulus of the fiber are low, the reinforcing effect in the concrete is not exhibited, and therefore the strength of the fiber bundle is preferably 15 cN / dtex or more and 30 cN / dtex or less.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely and in detail, the scope of the present invention is not limited to the following examples and comparative examples.
In addition, the preparation method and evaluation method of the polymer solution used in the Example are as follows.

(1) Preparation of polymer solution Into N-methyl-2-pyrrolidone (NMP), 50 parts by mass of paraphenylenediamine and 50 parts by mass of 3,4'-diaminodiphenyl ether were added, and 100 parts by mass of terephthalic acid dichloride was added. Then, a polycondensation reaction was performed to obtain a polymer solution of copolyparaphenylene terephthalamide. The intrinsic viscosity of the obtained polymer solution was 3.4.

(2) Measurement of fineness 100 m of the obtained fiber bundle was sampled using a known measuring instrument, and its mass was measured. The measurement was repeated twice, and the value obtained by multiplying the average of the obtained values by 100 was defined as the fineness.

(3) Measurement of single fiber fineness A value obtained by dividing the fineness value calculated in (2) by the number of filaments was defined as single yarn fineness.

(4) Measurement of tensile strength Using a tensile tester (manufactured by INSTRON, trade name: INSTRON, model: 5565 type), using a yarn test chuck, tensile of fiber bundles under the following conditions based on the procedure of ASTM D885 The strength was measured.
[Measurement condition]
Temperature: 25 ± 5 ° C
Humidity: 65 ± 10%
Test length: 750mm
Tensile speed: 250 mm / min Distance between chucks: 500 mm

(5) Calculation of flatness, irregularity and concaveness The cross-sectional image of the obtained fiber was taken with a microscope (trade name: Digital Microscope VHX-2000, manufactured by Keyence Corporation), and one single fiber was obtained from the image. The values of A, B, C, D and E were measured for the cross section. From the obtained values, flatness, irregularity and concaveness were calculated using the above-mentioned formulas (1), (2) and (3), respectively. In addition, about the value of D and E, it measured about all the concaveness which exists in a cross section, and made the average value the concaveness.

  The standard deviation is calculated for the flatness, irregularity and concaveness calculated repeatedly for five single yarns in the image, and the value obtained by dividing the standard deviation by the average value is multiplied by 100 to obtain the flatness, irregularity and Variation (CV%) was calculated for the convex ratio.

(6) Calculation of Gurley hardness According to JIS L 1096, the fiber bundle after applying the adhesive was measured, and the hardness was calculated.

<Example 1>
After the polymer solution described above is discharged from a die having a discharge hole shape having four short axis slits perpendicular to the longest axis slit and solidified in an aqueous solution having an NMP concentration of 30% through an air gap. After washing, drying, and drawing at a temperature of 530 ° C. 10 times, a wholly aromatic polyamide fiber having a cross-sectional shape shown in FIG. 1 and having a final yarn single yarn fineness of 6.5 dtex was obtained.

  The obtained wholly aromatic polyamide fiber was mixed with a glycidyl ether compound (manufactured by Nagase Chemtex, 0.4% by weight of Denacol EX611, Neocor SW-37 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 30% dioctylsulfosuccinatelium salt). Aqueous solution) 3.0 weight percent, blocked isocyanate (Daiichi Kogyo Seiyaku Co., Ltd., Elastolon BN-69) 10.0 weight percent, polyester-based blocked isocyanate (Daiichi Kogyo Seiyaku Co., Ltd., Elastron E-37) 13.0 weight percent and water 76.0 weight percent were added to form a first bath, and the resulting wholly aromatic polyamide fiber was dipped in the first bath and dried.

  Then, caustic soda water 0.4 weight percent, ammonia water 1.0 weight percent, resorcinol-formaldehyde initial condensate (Sumitomo Chemical Co., Ltd., Sumikanol 700S) 2.0 weight percent, styrene butadiene latex (manufactured by Nippon Zeon Co., Ltd.) 2518FS) 40.0 weight percent, formalin 1.0 weight percent, blocked isocyanate (Daiichi Kogyo Seiyaku Co., Ltd., Elastolon BN-69) 7.0 weight percent dissolved in water 17 weight percent Was used as a second bath agent, and the wholly aromatic polyamide fiber dipped in the first bath agent and dried was dipped in the second bath agent and then dried.

  By dipping in the second bath agent and drying, a wholly aromatic polyamide fiber bundle was obtained. Table 1 shows the measured physical properties of the wholly aromatic polyamide fiber and the wholly aromatic polyamide fiber bundle in which the wholly aromatic polyamide fiber is impregnated with the adhesive.

<Example 2>
Except for using a die having round holes at both ends of the longest axial slit, and adjusting the amount of dope discharged from the die so that the final yarn has a single yarn fineness of 2.6 dtex, the same procedure as in Example 1 was followed. Aromatic polyamide fibers and wholly aromatic polyamide fiber bundles were obtained. Table 1 shows the measured physical properties of the obtained wholly aromatic polyamide fiber and wholly aromatic polyamide fiber bundle.

<Example 3>
A total fragrance is produced in the same manner as in Example 1 except that a base having a three-leaf type discharge hole is used and the amount of dope discharged from the base is adjusted so that the final yarn has a single yarn fineness of 4.0 dtex. Group polyamide fiber and wholly aromatic polyamide fiber bundle were obtained. Table 1 shows the measured physical properties of the obtained wholly aromatic polyamide fiber and wholly aromatic polyamide fiber bundle.

<Comparative Example 1>
Except for using a mouthpiece having a round discharge hole shape, and adjusting the amount of dope discharged from the mouthpiece so that the final yarn has a single yarn fineness of 0.8 dtex, it is completely aromatic in the same manner as in Example 1. Polyamide fibers and wholly aromatic polyamide fiber bundles were obtained. Table 1 shows the measured physical properties of the obtained wholly aromatic polyamide fiber and wholly aromatic polyamide fiber bundle.

<Comparative example 2>
A wholly aromatic polyamide fiber and wholly aromatic were produced in the same manner as in Example 1 except that a die having a round discharge hole shape was used and the amount of dope discharged was adjusted to a single yarn fineness of 1.7 dpf. A polyamide fiber bundle was obtained. Table 1 shows the measured physical properties of a fully aromatic polyamide fiber bundle and a fully aromatic polyamide fiber bundle obtained by impregnating a fully aromatic polyamide fiber and a fully aromatic amide fiber with an adhesive.

<Comparative Example 3>
All aromatics were produced in the same manner as in Example 1 except that a die having a round discharge hole shape was used and the amount of dope discharged from the die was adjusted so that the final yarn had a single yarn fineness of 2.5 dtex. Polyamide fibers and wholly aromatic polyamide fiber bundles were obtained. Table 1 shows the measured physical properties of the obtained wholly aromatic polyamide fiber and wholly aromatic polyamide fiber bundle.

<Comparative example 4>
Other than adjusting the amount of dope discharged from the die to a final yarn single yarn fineness of 6.5 dtex using a die having a shape of a discharge hole having seven short axis slits perpendicular to the longest axis slit Obtained a wholly aromatic polyamide fiber and a wholly aromatic polyamide fiber bundle in the same manner as in Example 1. Table 1 shows the measured physical properties of the obtained wholly aromatic polyamide fiber and wholly aromatic polyamide fiber bundle.

<Comparative Example 5>
Using a die having a shape of a discharge hole that has four short axis slits perpendicular to the longest axis slit and the length of the longest axis slit is twice as long as that of the first embodiment. A wholly aromatic polyamide fiber and a wholly aromatic polyamide fiber bundle were obtained in the same manner as in Example 1 except that the discharge amount of the dope to be discharged was changed to the single yarn fineness 6.5 of the final yarn. Table 1 shows the measured physical properties of the obtained wholly aromatic polyamide fiber and wholly aromatic polyamide fiber bundle.

<Comparative Example 6>
Using a die having a shape of a discharge hole that has four short axis slits perpendicular to the longest axis slit, and the length of the short axis slit is twice that of the first embodiment, A wholly aromatic polyamide fiber and a wholly aromatic polyamide fiber bundle were obtained in the same manner as in Example 1 except that the discharge amount of the dope to be discharged was changed to the single yarn fineness 6.5 of the final yarn. Table 1 shows the measured physical properties of the obtained wholly aromatic polyamide fiber and wholly aromatic polyamide fiber bundle.

<Comparative Example 7>
A die having a shape of a discharge hole that has four short axis slits perpendicular to the longest axis slit and whose width of the longest axis slit is 0.5 times the width of the longest axis slit of Example 1. A wholly aromatic polyamide fiber and a wholly aromatic polyamide fiber bundle were obtained in the same manner as in Example 1, except that the amount of dope discharged from the base was changed to a final yarn single yarn fineness of 6.5. Table 1 shows the measured physical properties of the obtained wholly aromatic polyamide fiber and wholly aromatic polyamide fiber bundle.

(A) Maximum value of long side length of fiber (B) Maximum value of short side length (C) Of two sets of line segments connecting the bottom surfaces of recesses adjacent to B, the length is short Direction line
(D) Length between two contact points formed on both sides of the recess, and the length between the contact points (E) Length of the perpendicular drawn from the center of the tangent line to the contact point with the recess

Claims (5)

A wholly aromatic polyamide fiber, which is mainly composed of wholly aromatic polyamide and whose cross-sectional shape satisfies the following requirements a) and b) at the same time.
a) The cross-sectional shape of the fiber has 2 to 12 recesses.
b) In the fiber cross section, the maximum value of the length of the long side is A, the maximum value of the short side length is B, and the long of the two sets of line segments connecting the bottom surfaces of the recesses adjacent to B The length of the shorter line segment is C, a tangent line is drawn between the two convex portions formed on both sides of the concave portion, the length between the contact points is D, and a perpendicular line descending from the center of the tangent line, When the length to the contact point with the concave portion is represented by E, the flatness, irregularity, and concave values represented by the following formulas (1) to (3) are satisfied.
Flatness (A / B) = 1.5 to 3.0 (1)
Deformity (C / B) = 0.4 to 0.8 (2)
Concaveness (D / E) = 0.2 to 4.5 (3)   The wholly aromatic polyamide fiber according to claim 1, wherein the single fiber fineness of the aromatic polyamide fiber is in the range of 1.6 to 7.0 dtex.   The wholly aromatic polyamide fiber according to claim 1 or 2, wherein the aromatic polyamide fiber has a strength of 15 cN / dtex or more and 30 cN / dtex or less.   The wholly aromatic polyamide fiber according to any one of claims 1 to 3, wherein the wholly aromatic polyamide fiber is a para-type wholly aromatic polyamide fiber.   A concrete or mortar composition reinforced by the wholly aromatic polyamide fiber according to claim 1.

Images