JP2003253567A - Silicone oil for production of acrylic precursor fiber for carbon fiber and acrylic precursor fiber bundle for carbon fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicone oil for the production of an acrylic precursor for carbon fiber, free from troubles of the baking unevenness in the flame- resisting treatment and the generation of winding of a travelling yarn on a roller in a high-temperature environment and provide an acrylic precursor fiber bundle for carbon fiber storable over a long period, effective for improving the processability in baking and attaining a high tension, a high yarn density and a high production speed by using the silicone oil. <P>SOLUTION: The silicone oil for the production of an acrylic precursor fiber for carbon fiber has a maximum viscosity of 10,000-130,000 mPa.s defined in the specification in concentrated state. The acrylic precursor fiber bundle for carbon fiber is coated with the silicone oil. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silicone oil agent for producing an acrylic precursor fiber for carbon fiber and a bundle of acrylic precursor fiber for carbon fiber, which are excellent in cost performance.

[0002]

2. Description of the Related Art Polyacrylonitrile fiber is used as a precursor fiber for carbon fiber, and many improvement techniques have been disclosed in order to obtain carbon fiber having excellent performance. Carbon fiber is a fiber-forming process of spinning polyacrylonitrile-based fiber which is its precursor fiber, a flame-proofing process of heating and firing the fiber in an air atmosphere of 200 to 400 ° C. to convert it into oxidized fiber, nitrogen, argon, helium, etc. Is obtained by undergoing a carbonization step of further heating to 300 to 2500 ° C. in an inert atmosphere to carbonize, and is widely used as a reinforcing fiber of a composite material for aerospace applications, sports applications and general industrial applications, In particular, the demand expansion is remarkable in the aerospace and sporting goods fields in which higher and higher levels of performance are required.

By the way, since the properties of a composite material largely depend on the properties of the carbon fiber itself, the demand for higher performance of the composite material is ultimately the demand for higher performance of the carbon fiber itself. is there.

In order to improve the performance of carbon fiber, minute defects existing on the surface of the fiber cause deterioration of quality. Therefore, it is necessary to devise each manufacturing process in order to suppress the generation of this defect. Further, since it is required to achieve higher performance and further lower price, it is demanded to launch carbon fiber having excellent cost performance.

As a method of preventing the occurrence of surface defects,
There has been proposed a method in which an oil agent is applied to a yarn, and for example, a silicone oil agent is applied to prevent adhesion between single fibers and damage to the yarn in a carbonization process (see Patent Document 1). Furthermore, by adding an oil agent that combines silicone oil agents with various modifying groups such as amino-modified, epoxy-modified, and alkylene oxide-modified, it promotes resinification of the oil agent, and the single fiber indirect generated in the subsequent carbon treatment process. A method of suppressing the adhesion has been proposed (see Patent Document 2). However, even if the above method is effective in suppressing the adhesion between single fibers, the silicone to be imparted penetrates deeply inside the fiber bundle, and microvoids are formed in the surface layer to obtain carbon fibers having sufficient tensile strength. I couldn't do it.

[0006] As another cause of the decrease in tensile strength, oxygen required for the flameproofing reaction is generated between the single fibers, especially in the center of the fiber bundle during high tension or high density firing in the firing and flameproofing process. Not fully supplied. Therefore, the degree of progress of the flameproofing reaction, that is, burn marks occur, and finally the yarn breaks,
The fluff was generated and the physical properties of the carbon fiber were deteriorated.

Further, in terms of operability, in the process of high ambient temperature after applying the silicone oil and drying and densifying it in the spinning process, single fibers are taken into the oil which is transferred from the running fiber bundle onto the roller, and finally, There was a problem of winding around the roller. In addition, when the roller installed in the process of applying the silicone oil is operated for a long period of time, silicone, which is the main component of the oil, accumulates (gels), which adheres to the fiber bundle and then deteriorates due to yarn breakage or fuzzing. It was. Similarly, when the produced raw yarn is stored for a long time in high temperature and high humidity such as in summer, the oil agent applied to the fiber bundle absorbs moisture in the air and develops adhesiveness, so when pulling out the fiber bundle with the creel in the next step, The adhered monofilaments were peeled off from each other, resulting in deterioration of operability and quality due to generation of fluff. Therefore, it is necessary to adjust the production such that the fiber bundle is processed in the next step immediately after it is produced, or the temperature is controlled in a room.

As a technique for suppressing burn marks, a technique of using an acrylic precursor fiber having a specific surface roughness has also been proposed (see Patent Document 3). However, the smoothness of the monofilament surface, which is a technology for improving the strength of carbon fibers, is not always sufficient for the control of burn spots, and there is a demand for more effective burn spot suppression means. Further, it has not been clarified about measures against gelling in the roller winding in the high atmosphere and the oil applying step.

[0009]

[Patent Document 1] Japanese Patent Publication No. 12739/1980

[0010]

[Patent Document 2] Japanese Patent Publication No. 4-40152

[0011]

[Patent Document 3] Japanese Patent Laid-Open No. 11-217734

[0012]

In view of such background of the prior art, the present invention is a silicone oil agent for producing an acrylic precursor fiber for carbon fiber and a carbon fiber suitable for producing carbon fiber having excellent cost performance. A precursor fiber bundle for use is provided. That is, the silicone oil agent for producing an acrylic precursor fiber for carbon fiber, which does not induce burn spots in the flameproofing step, and which does not cause winding of running yarns at the roller portion at high ambient temperature, and by using this oil agent, It is intended to provide an acrylic precursor fiber bundle for carbon fibers, which can be stored for a long time in a fiber bundle, improves the firing processability, and enables high tension, high yarn density, and high speed conditions.

[0013]

The present invention employs the following means in order to solve the above problems. That is, the silicone oil agent for producing an acrylic precursor fiber for carbon fibers of the present invention is characterized in that the maximum viscosity at the time of concentration defined in the text is 10,000 to 130000 mPa · s. The acrylic precursor fiber bundle for carbon fibers of the present invention is characterized by being provided with such an oil agent.

[0014]

With respect to the above problems, the inventors of the present invention have a correlation between the viscosity of the silicone oil agent at the time of concentrating the silicone oil agent and the adhesive force when the thread is wound around the roller at a high atmospheric temperature.
Further, they have found that there is a correlation with the rate of change in the coefficient of friction between fiber bundles for long-term fiber bundle storage, and have reached the present invention.

That is, by controlling the viscosity of the silicone oil agent at the time of concentrating, which is measured by the method described below, and by adopting the silicone oil agent whose adhesive force is controlled within a specific range, the yarn roller at high ambient temperature Wrapping can be effectively suppressed, and by controlling the rate of change of the coefficient of friction of the fiber bundle-fiber bundle measured by the method described below within a specific range, it becomes possible to store for a long period of time. It was a finding.

Further, the acrylic precursor fiber for carbon fiber having the silicone oil agent of the present invention on its surface does not cause the running fiber bundle to be wound around the roller even at a high atmospheric temperature, and has less scorching during flame resistance. It is possible to provide excellent flame resistant fiber, effectively achieve the yarn breakage and fluff generation in the subsequent carbonization process, and thus, without deteriorating quality grade and operability, even in a hot and humid atmosphere such as in summer. It has been clarified that it can be stored for a long time.

As a result, compared with the conventional firing technology, it is possible to provide a high fiber bundle density, high tension, and high speed without lowering the productivity, and it is possible to provide a carbon fiber excellent in cost performance. Investigated.

The silicone oil of the present invention is required to have a maximum viscosity of 10,000 to 130000 mPa · s, preferably 10,000 to 100,000 mPa · s, and more preferably 15,000 to 80,000 mPa · s when concentrated. That is, when the viscosity exceeds 130000 mPa · s, the silicone component (gel) is accumulated in the tank for applying the oil agent in the yarn forming process and the roller on the outlet side of the tank, and the deposit adheres to the fiber bundle during traveling, and after drying and densification, In the drawing step, the deposits impede heat transfer into the fiber bundles, which deteriorates operability due to yarn breakage in the step or causes deterioration of quality due to generation of fluff, which is not preferable. Also, 10000
If it is less than mPa · s, the oil agent is hard to adhere to the fiber bundle, so in order to attach the required amount of oil agent to the fiber bundle, it is necessary to take adjustment means such as increasing the bath concentration or increasing the oil agent adhesion amount. However, the amount of oil used increases, which is not preferable.

Here, the maximum viscosity of the oil agent at the time of concentration means the maximum viscosity in the range where the solid content concentration of the oil agent is 50 to 90% by weight by evaporating the water content (volatile component) contained in the oil agent by air drying at room temperature. Is the numerical value of.

Specifically, constant temperature water set at 30 ° C. is circulated, and temperature equilibrium of the measuring section of the digital viscometer used for viscosity measurement is waited (about 1 hour). After that, the viscometer calibration standard solution is used to adjust the adjust ring of the viscometer so that the measured value matches the viscosity of the standard solution.

10 g of the oil agent is placed in a stainless petri dish (diameter: 75 mmφ), and the viscosity is measured in the range of 50 to 90% by weight. That is, from 50% by weight to every 5% by weight,
The respective viscosities are measured up to 90% by weight. At this time, the concentration is adjusted by first drying the sample solution whose concentration has been adjusted to 50% by weight at room temperature to evaporate the water content. At this time, be careful that the oil agent is not biased to the center of the stainless petri dish and that no air bubbles enter. After confirming that the sample solution has reached a predetermined concentration, the sample solution is set in a viscometer to measure the viscosity.

As described above, the silicone oil agent of the present invention has a maximum viscosity of 10,000 to 130,000 when concentrated.
Although it is in the range of mPa · s, the silicone oil having such a specific viscosity has an adhesive force of 1 to 2.3.
It has the special effect of being within N. If the adhesive force exceeds 2.3 N, the friction coefficient between the running fiber bundle and the roller in a high atmosphere becomes high, and the monofilament may wind around the roller, causing process troubles. Also,
If it is less than 1N, it can be freely deformed according to the space between the single fibers, so that it may be deposited thickly between the single fibers, causing burn spots in the flameproofing process, and causing deterioration of the quality of the carbon fibers. There is a risk that

The adhesive force of the silicone oil agent is measured as follows.

First, water mixed in the oil agent is evaporated in an oven at 50 ° C. for 10 hours. Next, the silicone oil is applied to the iron plate so that the thickness becomes 20 μm. Finally, fix the iron plate on the hot plate,
Heat treatment is performed at 0 ° C. for 1 minute.

An aluminum disc having a diameter of 20 mm was used as a test disc on the set iron plate, and the load was 3.0 at a speed of 9.2 mm / min.
Press vertically until it becomes N and fix it for 10 seconds in that state. After fixing, the speed of 9.2mm /
The aluminum disc is pulled up vertically in minutes, the maximum value of the load at that time is measured as the adhesive force, and the average value of 10 measurements is displayed.

The maximum viscosity and the adhesive strength at the time of concentration of such an oil agent can also be achieved by adjusting the silicone component and the composition which are the main ingredients of the oil agent. When the silicone oil agent component and composition are the same, the target can be achieved by selecting the type and molecular weight of the emulsifier used in combination.

The rate of change in the coefficient of friction between fiber bundles referred to in the present invention should preferably satisfy the following equation (1).

2 μ ≧ μ ′ (1) [wherein, μ is the coefficient of friction (−) between the fiber bundle and the fiber bundle immediately after spinning, and μ ′ is between the fiber bundle and the fiber bundle 60 days after spinning. Indicates the friction coefficient (-). ] The coefficient of friction between such a fiber bundle is measured as follows.

For μ, the fiber bundle wound up in the cylinder immediately after the yarn making is cut into 2 m. The cut fiber bundle is placed on the surface layer of the fiber bundle wound up in a cylinder perpendicularly to the longitudinal direction of the cylinder so that the fiber bundle is not twisted. A 200 g weight (W) is hung on one end of the yarn placed on the surface layer. Then, a spring scale is installed on the other side, and this spring scale is gradually pulled down. The weight on the other side rises when pulled down to some extent, so read the scale on the spring scale when the weight was raised. This is called tensile tension (F).

Next, for μ ′, the same measurement as μ is performed after leaving the fiber bundle for which μ has been measured for 60 days in a room at a temperature of 40 ° C. and a humidity of 60% (take an average value when measuring 10 times). . The numerical value is applied to the following formula (2) to obtain a friction coefficient μ or μ ′ between the fiber bundles.

Friction coefficient (μ or μ ′) = 1 / π × ln (F / W) (2) [In the formula, F represents tensile tension (g) and W represents weight weight (g). In the present invention, the silicone oil agent means an oil agent containing at least 0.1% by weight of silicone, and may be a silicone alone or in a solution state using an organic solvent or the like, but it is uniformly applied to the acrylic precursor fiber. From the viewpoint of properties and ease of application, an aqueous emulsion is preferably used.

To prepare such an aqueous emulsion,
An appropriate emulsifier may be added to the silicone, but from the viewpoint of satisfying the above-mentioned characteristics, the amount of the emulsifier is preferably 40 parts by weight or less with respect to 100 parts by weight of the silicone. Further, from the viewpoint of long-term stability, an antioxidant and the like can be added, but it is preferable to select one that does not inhibit the silicone crosslinking reaction.

The silicone used in the silicone oil agent of the present invention has a basic structure of polydimethylsiloxane and a part of the methyl group is modified. For the silicone used in the silicone oil agent of the present invention, it is necessary to select and use a silicone having a specific modifying group, and to specify the viscosity and the adhesive force at the time of concentration, and the rate of change of the coefficient of friction between fiber bundles. It is important from the top. As such a modifying group,
An amino group, an epoxy group, and an alkylene oxide group, and among these, those which further cause a crosslinking reaction by heating are preferably used. A silicone having a plurality of such modifying groups may be used, and it is sufficient that the three main silicones of these amino groups, epoxy groups and alkylene oxide groups are the main components. In addition to these, silicones having other different modifying groups may be mixed. You may use.

That is, from the viewpoint of uniformly imparting to the acrylic precursor fiber, it is a mixture of three components using amino-modified silicone and epoxy-modified silicone, and further adding alkylene oxide-modified silicone from the viewpoint of emulsion stability. It is preferable.

The modifying group of the amino-modified silicone may be a monoamine type or a polyamine type.
The amino group is the starting point of the cross-linking reaction, and the higher the modification amount is, the more the cross-linking reaction is promoted. However, since the gum up amount may increase, the modification amount is the terminal methyl group directly linked to Si. It is represented by the amount of amino-modified, but when the amount of terminal amino groups in the amino-modified silicone is converted to the weight of —NH ₂ , it is preferably 0.05 to 10% by weight,
0.1 to 5% by weight is more preferable.

The epoxy-modified silicone of the epoxy-modified group may be either alicyclic or glycidyl type, but alicyclic is preferred from the viewpoint of long-term stability. The amount of modification of the epoxy group is preferably from 0.05 to 10% by weight, more preferably from 0.1 to 5% by weight, when determined by the same conversion method as the amount of modification of the amino group described above. That is, since the epoxy group undergoes a cross-linking reaction with the amino group, it is preferable that both are the same. The ratio of such epoxy-modified silicone is 1 to 100 parts by weight of amino-modified silicone.
It is preferably 0 to 80 parts by weight, preferably 20 to 70.
Parts by weight, more preferably 30 to 60 parts by weight.

The proportion of alkylene oxide is 1 to 20 with respect to 100 parts by weight of amino-modified silicone.
The amount is preferably parts by weight, and preferably 4 to 17 parts by weight. If it exceeds 20 parts by weight, the crosslinking reaction may be delayed, and it may be difficult to obtain the effect on the viscosity, the adhesive force, and the friction coefficient, or the heat resistance may be deteriorated. If it is less than 1 part by weight, the effect of improving the emulsion stability may not be remarkably obtained.

Further, since the curing state of the silicone oil agent applied in the yarn making process has a great influence on the burning unevenness in flame resistance, the vibration period difference T measured by the method described later is used as an index showing the curing state of the oil agent. Is 0.03 to 0.40
Is more preferable, 0.05 to 0.35 is more preferable, and 0.10 to 0.30 is particularly preferable.

When it is less than 0.03, the curing of the oil agent does not proceed so much, so that the silicone oil agent freely moves between the single fibers and acts as a sealing agent, which is not preferable. On the other hand, if it exceeds 0.40, the curing is remarkably advanced, so that the constraint between the single fibers is strengthened and, as a result, burning and burning unevenness may occur, which is not preferable.

The vibration period difference T here means the vibration period of the silicone oil agent by the free damping vibration method of the rigid pendulum.

That is, based on the free damping vibration method of a rigid pendulum, a rigid pendulum type physical property tester manufactured by A & D Co., Ltd. (for example, RPT-300 manufactured by A & D Co., Ltd.).
0) is used to measure the vibration period.

Specifically, a silicone oil agent to be measured is placed on a zinc-plated steel plate coated substrate (for example, STP-012 manufactured by A & D Co., Ltd.) having a length of 5 cm, a width of 2 cm and a thickness of 0.5 mm. It is applied to the entire surface in the width direction of the substrate so as to have a thickness of 20 to 30 μm. Immediately after application, set the tester and start measurement. After adjusting the temperature to 30 ° C. in advance and setting the coating plate and the pendulum, the temperature is raised to 180 ° C. at a rate of 50 ° C./min and held at 180 ° C. for 10 minutes. Meanwhile, the period is continuously measured at 7 second intervals. The following pendulum is used.

Edge used: Knife-shaped edge (RBE-160 manufactured by A & D Co., Ltd.) Pendulum weight: Inertial performance rate: 15 g / 640 g · cm (FRB-100 manufactured by A & D Co., Ltd.) 0.03 ≦ T ≦ 0.4 T = T ₁ −T ₂ T ₁ : Vibration cycle at 30 ° C. (second) T ₂ : Vibration cycle after heat treatment at 180 ° C. for 10 minutes (second) Acrylic that constitutes the acrylic precursor fiber of the present invention As the system polymer, one having a constitution of 90% by weight or more of acrylonitrile and 10% by weight or less of a monomer copolymerizable with acrylonitrile is preferably used.

The above-mentioned copolymerizable monomers include acrylic acid, methacrylic acid, itaconic acid or their methyl esters, propyl esters, butyl esters, alkali metal salts, ammonium salts, allyl sulfonic acid, methallyl sulfonic acid, styrene. At least one selected from the group consisting of sulfonic acids and alkali metal salts thereof can be used.

Such an acrylic polymer can be obtained by a polymerization method such as emulsion polymerization, bulk polymerization and solution polymerization. As a measure of the degree of polymerization in this case, the intrinsic viscosity is preferably 1 or more, more preferably 1.25 or more. Particularly preferably, it is 1.5 or more. In addition, it is preferable that the intrinsic viscosity is 5 or less from the viewpoint of spinning stability. From the obtained polymer, dimethylacetamide, dimethylsulfoxide (hereinafter referred to as DMSO
), Dimethylformamide, nitric acid, rhodanesoda washing solution, etc. as a solvent, the polymer solution is prepared, spun by a wet spinning method, a dry-wet spinning method or the like, and the acrylic precursor fiber is subjected to other steps. It is possible to obtain an acrylic fiber as. In such an acrylic precursor fiber, a dry-wet spinning method is preferably used for producing a fiber bundle having a smooth single fiber surface with high productivity.

The dry / wet spinneret used in the acrylic precursor for carbon fiber of the present invention is preferably 0.5 m.
It is a pore plate in which hundreds to tens of thousands of pores having a size of m or less are opened, and the shape thereof is a circular shape, a rectangular shape, or a combination thereof.

In the case of the spinning method using a solvent and a plasticizer, the spun fiber bundle may be stretched directly in the bath, or may be stretched in the bath after washing and removing the solvent and the plasticizer. The stretching in the bath is preferably about 2 to 6 times in the bath at 50 to 98 ° C. Further, it is preferable to apply such a silicone oil agent after stretching in the bath. The silicone oil agent is often used as an emulsion, and at this time, it is preferable to use an emulsifier together.

The emulsifier is a compound having a surface activity that promotes the formation of an emulsion and stabilizes it, and a specific example thereof is polyethylene glycol alkyl ether. The applying method may be appropriately selected and used, and specifically, a dipping method, a kiss roller method, a guide oiling method or the like is adopted. The applied amount of silicone oil agent is 0.01 to
It is preferably 8% by weight, more preferably 0.02 to 5% by weight, particularly preferably 0.1 to 3% by weight. 0.01
If it is less than wt%, fusion of single fibers may occur and the quality grade of the resulting carbon fiber may deteriorate, which is not preferable. On the other hand, if it exceeds 8% by weight, the stability as an oil agent may deteriorate, which is not preferable.

The yarn to which the oil agent is applied in the present invention is
Drying and densification of the fiber bundle can be achieved by rapidly drying with at least one hot drum or the like. The higher the drying temperature is, the more the crosslinking reaction of the silicone oil agent is promoted. Therefore, the drying temperature is preferably 150 ° C or higher, more preferably 180 ° C or higher. The drying temperature and the drying time here can be appropriately changed. Also,
The dried and densified fiber bundle can be heat-treated as necessary while further drawing in a high temperature environment such as in pressurized steam. By such heat treatment, the oil agent spreads evenly and the effect of preventing the generation of surface defects due to the adhesion between single fibers becomes large, and a fiber bundle having more preferable fineness and crystal orientation can be obtained. It is preferable to appropriately select and use the steam pressure, the temperature, the post-stretching ratio, and the like during the post-stretching in a range that does not cause yarn breakage or fuzz.

The fiber bundle produced by the preferred method as described above can be fired by the following method to produce carbon fiber having excellent cost performance.

For the flameproofing treatment, conventionally used conditions can be adopted, and the flameproofing treatment temperature is preferably in the range of 200 to 300 ° C. in an oxidizing atmosphere. The stretch ratio of the flameproofing step is preferably 0.90 to 1.05, and 0.91 to
1.02 is more preferable.

The carbonization step is carried out in an inert atmosphere according to a conventional method. The ambient temperature is preferably 800 ° C. or higher from the viewpoint of enhancing the performance of the carbon fiber to be obtained, and the maximum temperature is appropriately selected according to the desired properties required of the carbon fiber.
If the temperature is lower than 0 ° C, the tensile strength and elastic modulus of the obtained carbon fiber may decrease, which is not preferable. The draw ratio in the carbonization step may be appropriately selected according to the desired properties of the carbon fiber within the range that does not cause yarn breakage or fluffing.

The obtained carbon fibers are subjected to electrolytic oxidation treatment in an acidic or alkaline electrolytic solution or oxidation treatment in a gas phase or a liquid phase to improve the adhesion between the carbon fibers and the matrix resin in the composite material. Can be improved.

After the oxidation treatment, it is preferable to wash with water and dry. After that, a sizing agent can be added to the carbon fiber according to a conventionally known method, if necessary.

[0055]

EXAMPLES The present invention will be described in more detail below with reference to examples. The measurement of each physical property value was performed based on the method shown below. The results measured in Examples and Comparative Examples are shown in Table 1. <Vibration cycle of silicone oil by free damping vibration method of rigid pendulum> Based on free damping vibration method of rigid pendulum, rigid pendulum type physical property tester RPT manufactured by A & D Co., Ltd.
The vibration period is measured using -3000. 5 cm long,
On a zinc-plated steel sheet coated substrate (STP-012 manufactured by A & D Co., Ltd.) having a width of 2 cm and a thickness of 0.5 mm, the silicone oil to be measured has a thickness of 2 in terms of pure content.
The coating is applied to the entire surface in the width direction of the substrate so as to be 0 to 30 μm.
Immediately after application, set the tester and start measurement. After adjusting the temperature to 30 ° C in advance and setting the coating plate and the pendulum, the temperature was raised to 180 ° C at a rate of 50 ° C / min, and
Hold for 10 minutes at 0 ° C. Meanwhile, the period is continuously measured at 7 second intervals. The following pendulum is used.

Edge used: Knife-shaped edge (RBE-160 manufactured by A & D Co., Ltd.) Pendulum weight: Inertial performance ratio: 15 g / 640 g · cm (FRB-100 manufactured by A & D Co., Ltd.) 0.03 ≦ T ≦ 0.4 T = T (30) −T (180) (30): Vibration cycle at 30 ° C. (second) (180): Vibration cycle after heat treatment at 180 ° C. for 10 minutes (second) <When silicone oil is concentrated Viscosity> 30 ° C Circulating constant temperature water, used for viscosity measurement Digital viscometer <D
VH-E type: Toki Sangyo> waits for temperature equilibrium of the measuring part (about 1 hour). Thereafter, the viscometer calibration standard solution is used to adjust the adjust ring of the viscometer so that the measured value matches the viscosity of the standard solution.

10 g of an oil agent was placed in a stainless petri dish (diameter: 75 mmφ), and water was evaporated by air drying at room temperature to a concentration of 5% by weight in the range of 50 to 90% by weight. At this time, the oil is injected so that it is not biased to the center of the stainless petri dish and bubbles do not enter. After confirming that the concentration has reached the prescribed level, the sample is set in a viscometer and measured. <Adhesive Strength of Silicone Oil Agent> First, water mixed in the oil agent is evaporated in an oven at 50 ° C. for 10 hours. Next, the silicone oil on the iron plate has a thickness of 2 in terms of pure content.
Apply so that the thickness becomes 0 μm. Finally, the iron plate is fixed on a hot plate and heat-treated at 180 ° C. for 1 minute.

An aluminum disc having a diameter of 20 mm was used as a probe on the set iron plate, and the load was 3. at a speed of 9.2 mm / min.
Press vertically until it becomes 0 N, and fix it for 10 seconds in that state. After fixing, the aluminum disc is pulled up vertically at a speed of 9.2 mm / min, and the maximum value of the load at that time is measured as the adhesive force (average value measured 10 times). <Strength and Elastic Modulus of Carbon Fiber Bundle> The strength of the carbon fiber bundle is determined by the method described in Japanese Industrial Standard (JIS) -R-7601 "Resin-impregnated strand test method". However, the resin-impregnated strand of the carbon fiber bundle to be measured is "BAKELITE" ERL4221 (100 parts by weight) / 3 boron trifluoride monoethylamine (3 parts by weight) /
Carbon fiber bundles were impregnated with acetone (4 parts by weight),
It is formed by curing at 0 ° C. for 30 minutes. The number of strands to be measured is 6, and the average value of each measurement result is the strength and elastic modulus of the carbon fiber bundle. <Fiber bundle-Friction coefficient between fiber bundles> μ is a value obtained by cutting a fiber bundle wound up in a cylinder by 2 m immediately after spinning. The cut fiber bundle is placed on the surface layer of the fiber bundle wound up in a cylinder perpendicularly to the longitudinal direction of the cylinder so that the fiber bundle is not twisted. A 200 g weight (W) is suspended from one end of the fiber bundle placed on the surface layer. Then install a spring only on the other side and gradually pull it down. The weight on the opposite side rises when pulled down to some extent, so read the scale with only the spring when the weight was raised. That is, the tensile tension (F) is used.

Next, for μ ′, the same measurement as μ is performed after leaving the fiber bundle for which μ has been measured in a room at a temperature of 40 ° C. and a humidity of 60% for 60 days (average value measured 10 times). Applying the numerical value to the following formula (2), the coefficient of friction between fiber bundles μ
Or μ '.

Friction coefficient (μ or μ ′) = 1 / π × ln (F / W) (2) [In the formula, F represents tensile tension (g), and W represents weight weight (g). Examples 1 to 3 By a solution polymerization method using dimethylsulfoxide as a solvent, spinning stock solutions having a concentration of a copolymer of 99 mol% acrylonitrile and 1 mol% itaconic acid of 20% were obtained. After the polymerization, ammonia gas was blown to reach pH 8.5 to neutralize itaconic acid and introduce an ammonium group into the polymer component, thereby improving the hydrophilicity of the spinning dope. The obtained spinning dope was kept at 40 ° C. and was once discharged into the air using a spinneret having a diameter of 0.15 mm and a hole number of 12000, and was allowed to pass through a space of about 3 mm.
The mixture was introduced into a coagulation bath consisting of a 35% by weight dimethylsulfoxide aqueous solution controlled at 0 ° C. and coagulated by a dry-wet spinning method.

The obtained coagulated yarn was washed with water, drawn 3 times in warm water at 70 ° C., and passed through an oil bath to apply a silicone oil.

The silicone oil component is a water emulsion system containing amino-modified silicone, epoxy-modified silicone and alkylene oxide-modified silicone. The concentration in this oil bath was adjusted by diluting with water so that the pure content was 2.0% by weight. Further, using a heating roller at 180 ° C., a drying treatment was performed for a contact time of 40 seconds.

The dry yarn thus obtained was drawn in a pressure steam of 0.4 MPa-G so that the total draw ratio of the yarn was 14 times, the single fiber fineness was 0.8 dtex, and the number of single fibers was 2
4000 acrylic precursors were obtained. The amount of the silicone oil agent attached to the obtained acrylic precursor was 1.0% by weight as a pure component. In addition, the rate of change in the coefficient of friction between fiber bundles was measured.

The obtained acrylic precursor was mixed with 240
In air at 280 ° C, the flameproofing time was 40 minutes, and the stretching ratio in the flameproofing step was 0.95.

Further, regarding the flame resistant yarn, 300 to 80
Maximum temperature 15 after pre-carbonization in an inert atmosphere at 0 ° C
Carbonized at 00 ° C. The draw ratio of the pre-carbonization step is 1.05
And Furthermore, the obtained carbonized yarn was subjected to 1 in an aqueous sulfuric acid solution.
After anodizing treatment of 0 Coulomb / g-CF, the number of fluffs existing in 20 m of the carbon fiber, the strength, and the elastic modulus were measured. At the same time, the roller wrapping and the amount of gum adhered on the roller portion in a high atmosphere were also evaluated. The maximum viscosity at the time of concentration of Examples 1 and 2 was when the concentration was 70% by weight. The friction coefficients of Examples 1 and 2 were as good as μ′0.11 with respect to μ0.1.

[Comparative Examples 1 to 3] Silicone components were the same as those in the examples, but the compositions were changed, and the same evaluations as the examples were performed. For Comparative Example 1, roller wrapping,
It can be seen that the amount of gum adhered is large and the CF quality is deteriorated.
In Comparative Example 2 as well, although the gum adhesion amount was small, roller wrapping was large and CF quality was also deteriorated. Further, the rate of change in the friction coefficient between the fiber bundles was 0.42 for the comparative example 1 and 0.42 or more for μ0.1.

[Comparative Example 4] The same procedure as in Example was carried out except that the oil component was a single component containing only amino-modified silicone. Under this condition, although the roller winding was small, the process could not be performed due to the frequent occurrence of fluff, so the firing was stopped.

[0068]

[Table 1]

[0069]

[Table 2]

As is clear from Table 2, in the examples, compared to the comparative examples, the occurrence of roller wrapping and the amount of gum adhered to the rollers at high ambient temperature are small and the operability is good. It was also confirmed that the carbon fiber strength was also significantly improved.

[0071]

EFFECTS OF THE INVENTION According to the present invention, it is possible to suppress burn spots in the flameproofing process and winding of the running yarn in the roller portion at high ambient temperature before flameproofing, and to produce a high-performance carbon fiber bundle. Can be well served.

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Claims (5)

[Claims] 1. The maximum viscosity at concentration defined in the text is 10
000 to 130000 mPa · s, a silicone oil agent for producing acrylic fiber for carbon fiber, which is characterized in that 2. The maximum viscosity at the time of concentration is 10,000 to 10
The silicone oil agent for producing an acrylic precursor fiber for carbon fiber according to claim 1, wherein the silicone oil agent is 0000 mPa · s. 3. The silicone oil agent for producing an acrylic precursor fiber for carbon fiber according to claim 1 or 2, wherein the adhesive force of the silicone oil agent defined in the present text is 1 to 2.3 N. 4. An acrylic precursor fiber bundle for carbon fiber, which is provided with the oil agent according to any one of claims 1 to 3. 5. The acrylic precursor fiber bundle for carbon fibers,
The acrylic precursor fiber bundle for carbon fiber according to claim 4, wherein the rate of change in the coefficient of friction between the fiber bundle and the fiber bundle defined in the present text satisfies the following formula (1). 2μ ≧ μ ′ ... Equation (1) [wherein μ is the coefficient of friction between the fiber bundle immediately after spinning and the fiber bundle (−), and μ ′ is the coefficient of friction between fiber bundle and the fiber bundle after 60 days after spinning] Represents (-). ]