JP2005089884A - Method for producing carbon fiber precursor acrylic fiber bundle - Google Patents

Abstract

An object of the present invention is to reduce fusion between single fibers during production of a carbon fiber precursor acrylic fiber bundle. In addition, prevent deterioration of operability, processability and carbon fiber bundle quality.
A method of bringing an acrylic fiber bundle into a water-swelled state, and introducing the acrylic fiber bundle in a water-swelled state into an oil agent treatment tank containing a treatment liquid in which an oil agent made of a mixture of a specific formulation is dispersed in water. A process of attaching the oil agent to the acrylic fiber bundle, a step of drying and densifying the acrylic fiber bundle to which the oil agent has adhered, and a water washing layer in which the dry and densified acrylic fiber bundle is filled with water. The water agent is washed with water to remove at least a part of the oil agent adhering to the acrylic fiber bundle, and the adhesion amount of the oil agent in the acrylic fiber bundle is 0.3 to 1.5% by mass. And a process for producing a carbon fiber precursor acrylic fiber bundle.
[Selection figure] None

Description

  The present invention prevents the occurrence of fusion between single fibers in a flameproofing process for converting a carbon fiber precursor acrylic fiber bundle into a flameproofed fiber bundle, and also produces a carbon fiber bundle having excellent quality and physical properties. The present invention relates to a method for producing a carbon fiber precursor acrylic fiber bundle that is suitable and has improved processability during the production of the carbon fiber bundle.

  Conventionally, acrylic fiber bundles are widely used as precursors of carbon fiber bundles. The acrylic fiber bundle is converted into a flame-resistant fiber bundle by heat treatment in an oxidizing atmosphere at 200 to 400 ° C., and the resulting flame-resistant fiber bundle is treated at a temperature up to about 700 ° C. in an inert atmosphere. A carbon fiber bundle is generally produced by performing a carbonization treatment followed by a carbonization treatment in an inert atmosphere at a temperature of at least 1000 ° C. The carbon fiber bundle obtained in this way is widely used as a suitable reinforcing fiber bundle used for a fiber-reinforced resin composite material due to its excellent physical properties.

  On the other hand, when the carbon fiber bundle is manufactured, the carbon fiber precursor acrylic fiber bundle is converted into a flame resistant fiber bundle. In the flame resistance process, fusion between single fibers occurs, the firing becomes uneven, and the fluff And troubles such as running out of bundles occur. In order to avoid this fusion, it is known that it is effective to apply an appropriate oil agent to the carbon fiber precursor acrylic fiber bundle before the flameproofing step, and many oil agents have been studied.

  The oil agent treatment in the production process of the carbon fiber precursor acrylic fiber bundle is first performed on the acrylic fiber bundle in a water swollen state. The oil used is thermal stable and converging to prevent potential defects in the carbon fiber precursor acrylic fiber bundle and the adhesion between single fibers, which is the cause of trouble in the firing process and deterioration of the carbon fiber bundle physical properties.・ It is important to have scratch resistance. If this oil agent has the property of preventing bundling and fusion between single fibers in the firing step, the oil agent application is completed in the first time. In many cases, the oil agent used in the oil agent treatment uses a substance having excellent heat stability such as amino-modified silicone or epoxy-modified silicone as a main component (Japanese Patent Laid-Open No. 58-214517 (Patent Document 1), etc.). It has been pointed out that the present oil treatment method has several drawbacks.

  When the oil agent applied to the acrylic fiber bundle in the water-swollen state also serves as a baked oil agent, the oil agent must have a function of protecting the acrylic fiber bundle surface not only against heat during drying densification but also against heat during firing. Don't be. As the main component of such an oil agent, amino-modified silicones and epoxy-modified silicones having a small modified group equivalent and a large molecular weight (a large number of modified groups per molecule) are cross-linked between molecules and within a molecule in the heat treatment step, and are heat resistant. It is often used because it has the property of forming a film. However, when such an oil agent drops from the acrylic fiber bundle in the drying and densification process of the water-swelling fiber bundle and adheres to the hot roll, the oil is gelled by intermolecular and intramolecular crosslinking on the roll after receiving the heat of the roll for a long time. (Gum-up) may cause troubles such as the acrylic fiber bundle being wound around the heat roll. In order to avoid such troubles due to the properties of the oil component, it is required to uniformly apply the minimum amount of the oil agent to the surface of the acrylic fiber bundle. There are adhering spots. For this reason, in reality, the amount of adhesion is often set high in order to avoid fusion in the firing process that occurs in a portion where the amount of adhesion is small. In this case, if there is an excessively adhered part, adhesion between single fibers occurs due to gum-up during the drying and heat-degraded oil component produced during firing.

  In order to solve this gum-up, oil agents such as the use of ingredients that are difficult to crosslink by heat, the use of “low silicone oils” containing non-silicone (aromatic complex esters, etc.) ingredients, and strict control of the amount of oil attached Possible measures include processing measures and drying process condition changes (decreasing heat roll temperature to make gum-up less likely to occur), but productivity and carbon fiber bundle performance are inferior to silicone oil treatment There are many disadvantages when introduced into the actual process.

Another problem with the oil bath treatment is the residue inside the acrylic fiber bundle of the oil. When the oil agent is applied, silicone, which is an oil agent component, penetrates into the inside of the acrylic fiber bundle due to the replacement of the water present in the water swollen acrylic fiber bundle with the oil agent treatment liquid (silicone emulsion diluent). The amount of oil that penetrates into the acrylic fiber bundle depends on the oil component, emulsion particle size, treatment bath concentration, and the like. The oil agent inside the acrylic fiber bundle is confined in the fiber matrix after drying and densification, and does not contribute to the modification of the surface properties of the acrylic fiber bundle. It will be adjusted higher and the oil cost will be higher. In addition, a part of the silicone remaining inside may remain after firing and become a defect. In addition, the silicone oil agent is dispersed as silicon oxide such as silica in the firing process, contaminates the inside of the firing furnace, and adheres to the product, causing a decrease in CF quality. Such a problem tends to become apparent when the amount of the oil agent is increased.
JP 58-214517 A

  The present invention stabilizes the firing process for a long period of time by reducing the problems related to the oil agent application process in the production of the carbon fiber precursor acrylic fiber bundle, particularly the fusion between single fibers during firing due to oil agent adhesion spots on the acrylic fiber bundle. It aims to improve the quality of carbon fiber bundles. Also, a carbon fiber precursor to which an oil agent treatment method is applied that suppresses generation of silicon oxide and the like in the flame resistance and carbonization processes, and thus can prevent deterioration in carbon fiber bundle quality such as operability, process passability, and strand strength. It aims at providing the manufacturing method of an acrylic fiber bundle.

The present invention employs the following means in order to solve the above problems. That is,
(A) making the acrylic fiber bundle into a water-swollen state;
(B) a step of guiding the acrylic fiber bundle in a water-swelled state to an oil agent treatment tank containing a treatment liquid containing an oil agent composed of the following mixture I and water, and attaching the oil agent to the acrylic fiber bundle; ,
(C) drying and densifying the acrylic fiber bundle to which the oil agent is attached;
(D) guiding the dried and densified acrylic fiber bundle to a water washing layer containing water, and performing a water washing treatment to remove at least a part of the oil agent adhering to the acrylic fiber bundle; A carbon fiber precursor acrylic fiber bundle having a carbon fiber precursor acrylic fiber bundle in which the adhesion amount of the oil agent in the acrylic fiber bundle is 0.3 to 1.5% by mass. is there.
Mixture I:
The aromatic ester represented by the following formula (1) is 60 to 89.5 mass%, the antioxidant is 0.5 to 14.0 mass%, and is represented by the following formula (2) or the following formula (3). A mixture containing 1.0 to 15% by mass of amino-modified silicone and 9 to 35% by mass of a nonionic surfactant having a residue rate of 1.0% by mass or less after heating at 250 ° C. for 2 hours.

(In Formula (1), R ¹ and R ² are each independently an alkyl group having 7 to 21 carbon atoms, A ¹ and A ² are each independently an ethylene group or a propylene group, and m and n are each independently 1-5)

(In the formula (2), i is 10 to 10000, j is 1 to 100. In addition, k is 1 to 10, L is 1 to 10, p is 0 to 5, R ³ to R ⁵ are each Independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms)

(In the formula (3), t is 10 to 10000, q is 1 to 10, r is 1 to 10, s is 0 to 5, R ⁶ to R ⁸ each independently a hydrogen atom or a 1 to 5 carbon atoms in the An alkyl group)
By setting it as the manufacturing method of such a carbon fiber precursor acrylic fiber bundle, fusion between single fibers can be reduced. Moreover, the fall of operativity, process passability, and carbon fiber bundle quality can be prevented.

  It is preferable that the adhesion amount of the oil agent in the acrylic fiber bundle dried and densified in the step (c) is 0.5 to 2.5% by mass. Moreover, in the said process (d), it is preferable that 25-60 mass% of the said oil agent adhering to the said acrylic fiber bundle is removed.

  According to the method for producing an acrylic fiber bundle for a carbon fiber precursor of the present invention, the adhesion spots of the spinning oil agent are reduced and the excessive adhesion oil agent is removed. Therefore, fusion during firing is effectively suppressed, and quality and physical properties are excellent. Carbon fiber bundles can be manufactured. Further, since the amount of the silicone degradation product scattered in the flameproofing process and the carbonization process is small, the operability and processability in the flameproofing process and the carbonization process are remarkably improved.

  The present inventors have solved the above-mentioned problems of the prior art and suppressed fuzz, bundle breakage or non-uniformity by suppressing adhesion and fusion between single fibers in the production process and flameproofing process of the carbon fiber precursor acrylic fiber bundle. Oil treatment method for carbon fiber precursor acrylic fiber bundle that can prevent firing and suppress generation of silicon oxide and the like in the firing process, and thus prevent deterioration of operability, process passability and carbon fiber bundle physical properties As a result of diligently examining the above, it is effective to apply an oil agent made of a specific mixture to an acrylic fiber bundle in a water-swollen state and dry and densify it, followed by water washing to partially remove the oil agent once adhered. I found.

  In the prior art, when applying an oil agent with a low affinity to the carbon fiber precursor acrylic fiber bundle, the amount of adhesion is often set higher to avoid adhesion and fusion at the unattached part of the oil agent. In this case, troubles in flame resistance due to adhesion / fusion due to generation of thermally deteriorated materials and poor oxygen diffusion into the acrylic fiber bundle were caused at the excessively adhered portion of the oil agent. The method proposed in the present invention removes the oil component that does not directly contribute to the protection of the fiber substrate only by adhering to the acrylic fiber bundle from the dried and densified acrylic fiber bundle, and removes the oil agent adhesion spots in the acrylic fiber bundle. This problem was solved by leveling.

  The present invention is described in detail below.

  In the present invention, a known acrylic fiber can be used for the acrylic fiber bundle before application of the oil agent, and the composition thereof is not particularly limited. However, a vinyl type copolymerizable with acrylonitrile unit of 95% by mass or more and acrylonitrile. An acrylic fiber obtained by spinning an acrylonitrile-based copolymer composed of 5% by mass or less of monomer units is preferable. Further, the copolymerizable vinyl-based monomer includes acrylic acid, methacrylic acid, itaconic acid, or at least one monomer selected from the group of monomers such as alkali metal salts or ammonium salts and acrylamide. The body is preferred for promoting the flameproofing reaction. The acrylic fiber bundle is usually in a state where 1000 to 100000 acrylic fibers are collected. The method for producing such an acrylic fiber bundle made of acrylic fibers is not particularly limited, and any of the known wet, dry, and dry and wet spinning methods can be employed.

  In the present invention, first, the acrylic fiber bundle is brought into a water-swollen state. The water-swelled acrylic fiber bundle is obtained by replacing the spinning solvent with water in a washing step after spinning, and is a gel-state acrylic fiber bundle before drying and densification.

  Next, the acrylic fiber bundle in the water-swelled state is guided to an oil agent treatment tank containing an oil agent composed of the following mixture I and a treatment liquid containing water, and the oil agent is attached to the acrylic fiber bundle.

  Here, the mixture I is 60 to 89.5% by mass of an aromatic ester represented by the formula (1) described later, 0.5 to 14.0% by mass of an antioxidant, and a formula (2) described later. ) Or 1.0 to 15% by mass of the amino-modified silicone represented by formula (3) and 9 to 35% by weight of a nonionic surfactant having a residue ratio of 1.0% by mass or less after heating at 250 ° C. for 2 hours. %.

  In the present invention, an aromatic ester represented by the following formula (1) can be used as the aromatic ester.

(In Formula (1), R ¹ and R ² are each independently an alkyl group having 7 to 21 carbon atoms, A ¹ and A ² are each independently an ethylene group or a propylene group, and m and n are each independently 1-5)
Specifically, the carboxylic acid forming the R ¹ part or R ² part is preferably selected from higher fatty acids such as lauric acid, myristic acid, palmitic acid and stearic acid. Moreover, when m and n exceed the above-mentioned range, heat resistance will fall and the adhesion | attachment between single fibers may occur in a drying process. When a plurality of A ¹ and A ² are present, an ethylene group and a propylene group may be mixed. In addition, the aromatic ester shown by Formula (1) may be a mixture of a some compound, Therefore, m and n may not be an integer.

  The content rate of the said aromatic ester in the mixture I of this invention exists in the range of 60-89.5 mass%. When the amount is less than 60% by mass, the carbon fiber bundle performance such as strand strength tends to be lowered. When the amount is more than 89.5% by mass, adhesion in the production process of the carbon fiber precursor acrylic fiber bundle and high-temperature baking treatment is suppressed. Since the effect is insufficient and the process passability and the performance of the carbon fiber bundle may be lowered, it is not preferable. Preferably, it is 70-80 mass%.

  In the present invention, a known antioxidant can be used as the antioxidant. Specifically, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl) -4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,3,5-tris (4-tert-butyl-3-hydroxy-2) , 6-Dimethylbenzyl) isocyanuric acid, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 4,4′-butylidenebis (3-methyl- 6-t-butylphenyl-ditridecyl phosphite) and the like are preferably used, and these may be used alone or in combination.

  The content rate of the said antioxidant in the mixture I of this invention exists in the range of 0.5-14.0 mass%. If the amount is less than 0.5% by mass, the heat resistance effect is not sufficient, and even if added in excess of 14.0% by mass, the effect of improving the heat resistance is not changed. This is not preferable because it may remain in the modified yarn or the stability of the emulsion may be lowered. Preferably, it is 1.0-10.0 mass%.

  In the present invention, as the amino-modified silicone, an amino-modified silicone represented by the following formula (2) or the following formula (3) can be used.

(In the formula (2), i is 10 to 10000, j is 1 to 100. In addition, k is 1 to 10, L is 1 to 10, p is 0 to 5, R ³ to R ⁵ are each Independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms)

(In the formula (3), t is 10 to 10000, q is 1 to 10, r is 1 to 10, s is 0 to 5, R ⁶ to R ⁸ each independently a hydrogen atom or a 1 to 5 carbon atoms in the An alkyl group)
The amino-modified silicone of the above formula (2) is effective in improving the affinity for the acrylic fiber bundle and the heat resistance. The amino-modified part of the above formula (2) is an aminopropyl group [—C ₃ H ₆ NH ₂ , k = 3, p = 0, R ⁴ and R ⁵ are hydrogen atoms in the amino-modified part of the formula (2)] Or N- (2-aminoethyl) aminopropyl group [—C ₃ H ₆ NHCH ₂ CH ₂ NH ₂ , k = 3, L = 2, p = 1 in the amino-modified part of formula (2), R ³ , R ⁴ and R ⁵ are particularly preferably a hydrogen atom. If i and j in the formula (2) are out of the above ranges, it is not preferable because the performance and heat resistance of the carbon fiber bundle are deteriorated. If i is smaller than 10, the heat resistance is low and fusion between single fibers cannot be prevented. On the other hand, when i is larger than 10,000, it is difficult to disperse in water, and it cannot be uniformly applied to the surface of the acrylic fiber bundle. When j is smaller than 1, sufficient heat resistance is not exhibited, and fusion between single fibers cannot be effectively prevented. On the other hand, if j is larger than 100, the heat resistance of the oil agent itself is lowered, so that fusion between single fibers cannot be prevented. A preferable range is 50 to 1000 for i and 1 to 10 for j. The amino-modified silicone represented by the formula (2) may be a mixture of a plurality of compounds, and therefore, i, j, k, L, and p may not be integers.

The amino-modified silicone of the above formula (3) is effective in improving the affinity for the acrylic fiber bundle and the heat resistance. The amino-modified moiety of the above formula (3) is an aminopropyl group [—C ₃ H ₆ NH ₂ , q in Y of formula (3), s = 0, R ⁷ , R ⁸ are hydrogen atoms], or N- (2-aminoethyl) aminopropyl group [—C ₃ H ₆ NHCH ₂ CH ₂ NH ₂ , Y in formula (3), q = 3, r = 2, s = 1, R ⁶ , R ⁷ and R ⁸ are particularly preferably a hydrogen atom. If t in the formula (3) is out of the above range, the heat resistance and performance of the carbon fiber bundle are deteriorated, which is not preferable. A preferred range is 50 to 1000 for t. The amino-modified silicone represented by the formula (3) may be a mixture of a plurality of compounds, and therefore t, q, r, and s may not be integers.

  Moreover, the amino modified silicone shown by Formula (2) or Formula (3) can also be used together. The blending ratio at that time is preferably 20/80 to 80/20 (mass ratio).

  In this invention, by mix | blending the amino modified silicone component shown by said Formula (2) or Formula (3) with the mixture I, the adhesion | attachment between the single fibers in the drying process after oil agent provision can be suppressed effectively. The content of the amino-modified silicone in the mixture I of the present invention can be appropriately adjusted in the range of 1.0 to 15% by mass according to the production type of the carbon fiber precursor acrylic fiber bundle and the conditions of the drying process. it can. If the amount is less than 1.0% by mass, the effect of suppressing adhesion / fusion between single fibers in the spinning step and the firing step is not sufficient, and if it is higher than 15% by mass, the acrylic fiber bundle after the dry densification step Convergence deteriorates and process passability decreases. Preferably, it is 2.0-10.0 mass%.

  In the present invention, as the nonionic surfactant, a nonionic surfactant having a residue rate of 1.0% by mass or less after heating at 250 ° C. for 2 hours can be used. Preferable examples include polyoxyalkylene glycol fatty acid esters and alkylene oxide adducts of aliphatic alcohols, and the alkyl chain in the hydrophobic part may be linear or branched. These may be used alone or in combination. The nonionic surfactant preferably has an HLB of 6 to 16. However, since it is not preferable that these nonionic surfactants remain in the fiber bundle after flameproofing or the fiber bundle after carbonization as a heating residue in the firing step, the residual rate after heating at 250 ° C. in air for 2 hours Needs to be 1.0% by mass or less. It is preferable that it is 0.5 mass% or less. Such nonionic surfactants, for example, the number of repeating hydrophilic oxyalkylene units, the type of oxyalkylene units and the form of repeating oxyalkylene units are such that the aqueous dispersion of mixture I becomes a stable emulsion. It can be selected appropriately.

  The content rate of the said nonionic surfactant in the mixture I of this invention is the range of 9-35 mass%. If the amount is less than 9% by mass, the stability of the emulsion tends to be reduced and adhesion spots (unevenness) to the acrylic fiber bundle tend to occur. If the amount is more than 35% by mass, the performance of the carbon fiber bundle such as the strand strength decreases. Tend. Preferably, it is 15-30 mass%.

  In the present invention, a water-swollen state is obtained by using an oil agent composed of the mixture I in which the above aromatic ester, antioxidant, amino-modified silicone and nonionic surfactant are blended in the above ratio, and a treatment liquid containing water. The oil agent is attached to the acrylic fiber bundle. Usually, the treatment liquid is in the form of an aqueous emulsion in which the mixture I is dispersed in water.

  Preparation of the water-based emulsion was carried out, for example, by mixing and stirring an aromatic ester and amino-modified silicone, adding an antioxidant while heating as necessary, and adding and stirring an emulsifier (nonionic surfactant) to this mixture. An aqueous emulsion of mixture I is obtained by dispersing the product in water. Each component can be mixed or dispersed in water using a propeller, a homomixer, a homogenizer or the like. In addition, an antistatic agent, a penetrating agent, an antifoaming agent, a preservative, and the like may be appropriately blended with the oil agent composed of the mixture I in order to improve the characteristics.

  As a method for attaching the oil agent comprising the mixture I used in the present invention to the acrylic fiber bundle in a water-swollen state, a known method such as roller oiling or dipping can be used.

  In this invention, it is preferable that the adhesion amount of the said oil agent with respect to the acrylic fiber bundle of a water swelling state is 0.5-2.5 mass% after drying densification mentioned later, 0.8-2. It is more preferable that it is 0 mass%. When the adhesion amount is lower than 0.5% by mass, the amount of the oil remaining in the acrylic fiber bundle after the water washing process described later is reduced, and it becomes difficult to sufficiently express the original function of the oil. On the other hand, when the adhesion amount is higher than 2.5% by mass, there is still a tendency for adhesion in the firing process to occur frequently because the oil agent over-adhered portion still exists in the acrylic fiber bundle after the water washing treatment described later. Moreover, removal of the oil agent adhering in a large amount is not preferable because it increases costs and damages the acrylic fiber bundle during water treatment.

  In the present invention, the acrylic fiber bundle to which the oil agent is attached is dried and densified in a subsequent drying step. There is no restriction | limiting in particular in the method, For example, it can carry out by well-known methods, such as the method of drying continuously on a hot roll whose surface temperature is 130-190 degreeC. Moreover, the extending | stretching process after a drying process can be performed as needed.

  In the present invention, next, the dried and densified acrylic fiber bundle is guided to a water washing tank containing water, and at least a part of the oil agent adhering to the acrylic fiber bundle is removed. This water washing step may be performed between the drying step and the stretching step, after the stretching step, or immediately before the firing step. The purpose of this water washing step is to remove at least a part of the oil agent adhering to the acrylic fiber bundle. There are cleaning methods such as dipping method and liquid flow penetration method, but regardless of the cleaning method, the single fiber is damaged and cut, or it causes potential damage causing thread breakage in the subsequent process. It is important to set a condition that does not.

  About the amount of oil agent removal, it is made for the adhesion amount of the oil agent in an acrylic fiber bundle to be 0.3-1.5 mass%. If the adhesion amount of the oil agent in the acrylic fiber bundle is out of this range, process troubles due to fusion or adhesion between single fibers occur in the firing process, and the quality of the carbon fiber bundle deteriorates, which is not preferable. Preferably, it is 0.5-1.3 mass%.

  Moreover, it is preferable that 25 mass%-60 mass% of the oil agent adhering to an acrylic fiber bundle is removed by this process, and it is more preferable that 35 mass%-50 mass% is removed. Although this removal rate depends on the swelling state of the acrylic fiber bundle, etc., the oil agent present in the vicinity of the surface of the acrylic fiber bundle is removed to a degree sufficient to exert the effect of the present invention by removing 25% by mass or more. It is thought that there is. That is, even if the removal is 25% by mass, superiority to the usual oil agent treatment is recognized in the firing step. By thoroughly removing the oil agent, the effect of the present invention will be exhibited more, but if the degree of removal is too much, the effect of the oil agent film protecting the fiber substrate will be reduced, such as fusion during firing Therefore, the upper limit of preferable oil agent removal is 60% by mass.

  In the method of the present invention, since the oil agent once adhered to the acrylic fiber bundle is dropped into the water washing tank, there is a possibility that the cost of the oil agent and the treatment of the waste liquid may become a problem. For example, the washing treatment liquid is recovered. After analyzing the components in the liquid and adjusting the composition, it can be re-emulsified and put into an aqueous emulsion of oil. In this way, the oil cost can be reduced and the problem of environmental burden can be avoided at the same time.

  According to the method for producing a carbon fiber precursor acrylic fiber bundle of the present invention as described above, the adhesion spot of the spinning oil is reduced and the excessively adhered oil agent is removed, so that the fusion during firing is effectively suppressed, A carbon fiber bundle excellent in quality and physical properties can be produced. Further, since the amount of the silicone degradation product scattered in the flameproofing process and the carbonization process is small, the operability and processability in the flameproofing process and the carbonization process are remarkably improved. A carbon fiber bundle obtained from such a carbon fiber precursor acrylic fiber bundle is suitable as a reinforcing fiber bundle used for a fiber-reinforced resin composite material.

  The present invention will be described more specifically with reference to the following examples, but the method for producing the carbon fiber precursor acrylic fiber bundle of the present invention is not limited thereto. In addition, nonionic surfactant heating residue, oil agent adhesion amount, oil agent removal rate, number of fusions between single fibers, flameproofing process pre-process passability, silicone oil agent decomposition product scattering amount and carbon fiber strand strength are as follows. evaluated.

[Nonionic surfactant heated residue]
A nonionic surfactant (2.0 g) was precisely weighed in an aluminum petri dish (diameter 60 mm, depth 10 mm), and the residue rate was calculated for the residue after heating in air at 250 ° C. for 2 hours. The larger the heating residue rate, the greater the possibility that the thermally deteriorated nonionic surfactant will remain in the fiber bundle after flame resistance or in the fiber bundle after carbonization.

[Oil agent adhesion, oil agent removal rate]
The oil adhesion amount was measured by a solvent extraction method. In addition, the oil agent removal rate is expressed in mass% from the oil agent adhesion amount after drying the acrylic fiber bundle treated in the subsequent water washing step, based on the oil agent adhesion amount of the dried and densified acrylic fiber bundle.

[Number of fusions between single fibers (number of fusions)]
The carbonized carbon fiber bundle is cut into 3 mm lengths, dispersed in acetone, and after stirring for 10 minutes using a magnetic stirrer, the total number of single fibers and the number of fusions are counted, and the number of fusions per 100 single fibers. Was calculated. The evaluation criteria are as follows.
○: Number of fusions (pieces / 100 pieces) ≦ 1
×: Number of fusions (pieces / 100 pieces)> 1
[Passability before flameproofing process (process passability)]
Using the obtained carbon fiber precursor acrylic fiber bundle, when the carbon fiber bundle was produced continuously for one week, by the number of times the carbon fiber precursor acrylic fiber bundle was wound around the roll or the like before the flameproofing step, The degree of fluff and thread breakage of the carbon fiber precursor acrylic fiber bundle was evaluated. The evaluation criteria are as follows.
○: Number of windings (times / day) ≦ 1
Δ: 1 <number of windings (times / day) ≦ 10
×: Number of windings (times / day)> 10
[Amount of silicone oil decomposed product scattering (silica scattering)]
Using the obtained carbon fiber precursor acrylic fiber bundle, the amount of silicone oil decomposed material scattered in the flameproofing furnace was represented by the cleaning frequency of the flameproofing furnace when the carbon fiber bundle was produced continuously for one week. . Cleaning was carried out by interrupting firing when the silica trapping filter in the air circulation line of the flameproofing furnace was clogged and the pressure loss of the circulation pump increased. The evaluation criteria for silica scattering are as follows.
○: Number of cleanings (times / week) ≤ 1
×: Number of cleanings (times / week)> 1
[Carbon fiber strand strength (CF strength)]
It measured according to the epoxy resin impregnation strand method prescribed | regulated to JIS-R-7601. The number of measurements was 10 times, and the average value was taken.

(Example 1)
A mixture emulsion was prepared in the following manner.

As the aromatic ester A, in formula (1), A ¹ and A ² are both ethylene groups, m = 1, n = 1, and the carboxylic acids forming R ¹ part and R ² part are both lauric acid. A substance (1), a substance (5) which is pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] as an antioxidant B, As the modified silicone C, a substance in which k = 3, L = 2, p = 1 in formula (2), R ³ , R ⁴ , R ⁵ are hydrogen atoms, i = 60, j = 1 (8) and the nonionic surfactant D, polyoxyethylene lauryl ether [EO (ethylene oxide) unit number of 10% by mass of heated residue (mass after heating at 250 ° C., 2 hours): 10: 10 , HLB: 14.0] with a substance (12) , Component A, Component B, Component C, and Component D were mixed at a mass ratio of 71: 2: 4: 23 as shown in Table 1, and ion-exchanged water was added (the total concentration of Components A to D was 25). Adjusted to mass%), emulsified with a homomixer, and further subjected to secondary emulsification at 30 MPa with a high-pressure homogenizer to obtain a mixture emulsion.

  An acrylonitrile copolymer (acrylonitrile unit / methacrylic acid unit / acrylamide unit mass ratio 97.1 / 0.9 / 2.0) was dissolved in dimethylacetamide, the polymer concentration was 21% by mass, and the viscosity at 60 ° C. A 500 poise spinning stock solution was prepared and discharged from a spinneret having a pore size (diameter) of 75 μm and a pore number of 12,000 into a coagulation bath filled with a dimethylacetamide aqueous solution at 35 ° C. and 69% by mass to obtain a coagulated yarn. The coagulated yarn was desolvated in a water washing tank and stretched 5 times to obtain an acrylic fiber bundle in a water swollen state.

  The acrylic fiber bundle in the water-swelled state is led to an oil agent treatment tank filled with a diluent (aqueous emulsion) in which the mixture emulsion is dispersed in water and the oil agent concentration is adjusted to 0.9% by mass, and the oil agent is attached. Then, it was dried and densified with a heating roll having a surface temperature of 130 ° C., and further stretched 1.7 times between heating rolls having a surface temperature of 170 ° C.

  The acrylic fiber bundle at this stage had a single yarn fineness of 1.2 dtex, a tensile strength of 7 g / dtex, an elongation of 10.5%, and the amount of oil attached was 1.30% by mass.

  The acrylic fiber bundle after drying and densification was washed with water by a method of penetrating the water flow while being continuously immersed in water. Then, it dried with the heating roll with a surface temperature of 130 degreeC, and obtained the carbon fiber precursor acrylic fiber bundle. The oil agent removal rate was 42% by mass (the amount of oil agent adhered at this time was 0.75% by mass).

  This carbon fiber precursor acrylic fiber bundle is passed through a flameproof furnace having a temperature gradient of 230 to 270 ° C. over 60 minutes, and further fired in a carbonization furnace having a temperature gradient of 300 to 1300 ° C. in a nitrogen atmosphere. A carbon fiber bundle was obtained.

  Evaluation of the number of carbon fiber bundles fused and carbon fiber strand strength (CF strength) obtained here, passability before the flameproofing process, and the amount of silicone decomposition products in the flameproofing process (evaluated by the number of cleanings of the furnace) Is shown in Table 1. The evaluation results of the number of fusions, process passability, and silica scattering were “good” and the CF strength was also high.

(Examples 2-9)
Carbon fiber precursor acrylic in the same manner as in Example 1, using aromatic esters A, antioxidants B, amino-modified silicones C and nonionic surfactants D using the materials shown in Table 1 and the oils blended in the blending ratio. Fiber bundles and carbon fiber bundles were produced. The results are summarized in Table 1. The evaluation results of the number of fusions, process passability, and silica scattering were “good” and the CF strength was also high.

(Comparative Examples 1-11)
Carbon fiber precursor acrylic in the same manner as in Example 1, using aromatic ester A, antioxidant B, amino-modified silicone C and nonionic surfactant D using the materials shown in Table 2 and the oils blended in the blending ratio. Fiber bundles and carbon fiber bundles were produced. The results are summarized in Table 1. At least one item of the number of fusions, process passability, and silica scattering was “Δ” or “x”. Moreover, CF intensity | strength was low. In Comparative Examples 2, 4, 5, 6, 7, 9, and 10, since the firing was unstable and continuous firing for one week was not possible, evaluation on silica scattering was not performed.

Substances (1) to (16) in Table 1 and Table 2 represent the following substances.
(1) Dilauryl ester of bisphenol A ethylene oxide 2-mol adduct. m = 1, n = 1
(2) Dilauryl ester of bisphenol A ethylene oxide 4 mol adduct. m = 2, n = 2
(3) Dilauryl ester of bisphenol A ethylene oxide 2 mol / propylene oxide 2 mol adduct. m = 2, n = 2
(4) Dilauryl ester of 12 mol adduct of bisphenol A with ethylene oxide. m = 6, n = 6
(5) Pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]
(6) Triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate]
(7) 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid (8) amino-modified silicone [k = 3, L = 2 in formula (2) p = 1, R ³ , R ⁴ , R ⁵ are hydrogen atoms, i = 60, j = 1]
(9) Amino-modified silicone [in formula (2), k = 3, L = 2, p = 1, R ³ , R ⁴ , R ⁵ are hydrogen atoms, i = 300, j = 8]
(10) Amino-modified silicone [in formula (3), q = 3, s = 0, R ⁷ , R ⁸ are hydrogen atoms, t = 60]
(11) Amino-modified silicone [in formula (2), k = 3, L = 2, p = 1, R ³ , R ⁴ , R ⁵ are hydrogen atoms, i = 2000, j = 150]
(12) Polyoxyethylene lauryl ether [EO (ethylene oxide) unit number: 10, HLB: 14.0, heating residue (mass after heating at 250 ° C./2 hours): 0.4 mass%]
(13) Polyoxyethylene lauryl ether [EO unit number: 5, HLB: 10.8, heating residue (mass after heating at 250 ° C./2 hours): 0.6 mass%]
(14) Polyoxyethylene tridecyl ether [EO unit number: 10, HLB: 13.7, heating residue (mass after heating at 250 ° C./2 hours): 0.7 mass%]
(15) Palm fatty acid reduced alcohol ethylene oxide adduct [EO unit number: 9, HLB: 13.1, heating residue (mass after heating at 250 ° C./2 hours): 5.0 mass%]
(16) Polyoxyethylene hydrogenated castor oil [number of EO units: 10, HLB: 12.5, heating residue (mass after heating at 250 ° C./2 hours): 15% by mass]

Claims (3)

(A) making the acrylic fiber bundle into a water-swollen state;
(B) a step of guiding the acrylic fiber bundle in a water-swelled state to an oil agent treatment tank containing a treatment liquid containing an oil agent composed of the following mixture I and water, and attaching the oil agent to the acrylic fiber bundle; ,
(C) drying and densifying the acrylic fiber bundle to which the oil agent is attached;
(D) guiding the dried and densified acrylic fiber bundle to a water washing layer containing water, and performing a water washing treatment to remove at least a part of the oil agent adhering to the acrylic fiber bundle; A carbon fiber precursor acrylic fiber bundle having a carbon fiber precursor acrylic fiber bundle having an adhesion amount of the oil agent of 0.3 to 1.5% by mass in the acrylic fiber bundle.
Mixture I:
The aromatic ester represented by the following formula (1) is 60 to 89.5 mass%, the antioxidant is 0.5 to 14.0 mass%, and is represented by the following formula (2) or the following formula (3). A mixture containing 1.0 to 15% by mass of amino-modified silicone and 9 to 35% by mass of a nonionic surfactant having a residue rate of 1.0% by mass or less after heating at 250 ° C. for 2 hours.

(In Formula (1), R ¹ and R ² are each independently an alkyl group having 7 to 21 carbon atoms, A ¹ and A ² are each independently an ethylene group or a propylene group, and m and n are each independently 1-5)

(In the formula (2), i is 10 to 10000, j is 1 to 100. In addition, k is 1 to 10, L is 1 to 10, p is 0 to 5, R ³ to R ⁵ are each Independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms)

(In the formula (3), t is 10 to 10000, q is 1 to 10, r is 1 to 10, s is 0 to 5, R ⁶ to R ⁸ each independently a hydrogen atom or a 1 to 5 carbon atoms in the An alkyl group)   The method for producing a carbon fiber precursor acrylic fiber bundle according to claim 1, wherein an adhesion amount of the oil agent in the acrylic fiber bundle dried and densified in the step (c) is 0.5 to 2.5 mass%. . The method for producing a carbon fiber precursor acrylic fiber bundle according to claim 1 or 2, wherein in the step (d), 25 to 60 mass% of the oil agent adhering to the acrylic fiber bundle is removed.