JPS6233861A - Apparatus for applying sizing agent to carbon fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of applying a sizing agent to carbon fibers.

[Prior Art] Conventionally, carbon fibers have been used in various applications due to their excellent mechanical, chemical, and electrical properties and light weight, such as structural materials for aerospace such as aircraft and rockets, tennis rackets, golf shafts, and fishing rods. It is widely used in sports equipment such as sports equipment, and it is also expected to be used in transportation equipment such as ships and automobiles.

By the way, carbon fiber is inherently rigid and brittle, and has poor bending and abrasion resistance, so it is susceptible to contact with rollers and abrasion on thread guides during the manufacturing process or higher processing process.
In addition, fuzz is likely to occur due to abrasion by sharks during warping or various bending operations, which may sometimes lead to thread breakage. Additionally, carbon fibers themselves generally have poor adhesion to the matrix. For this reason, carbon fibers are usually treated with various sizing agents, which give the carbon pAN a cohesive property, improve its bending resistance and abrasion resistance, and improve its adhesion to 71~Rix. is.

In that case, the sizing agent (=J) is obtained by immersing the yarn to be treated in the sizing solution 4 in the sizing bath 2, as shown in FIG. Generally, it is continuously run through an impregnating roller 3.

However, the current trend in the field of carbon fiber production is to increase the number of yarns and speed up the manufacturing process in order to reduce manufacturing costs. The more likely it is that the 4-noising agent will adhere to the yarn in spots. This is the main cause of problems such as frequent yarn breakage occurring during the carbon fiber manufacturing process or high-order processing process.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned problems of the prior art;
In other words, iJ3! The purpose is to reduce the adhesion spots of the leasing agent and prevent the occurrence of fuzz and thread breakage during subsequent processes.

[Means for Solving the Problems] The above object of the present invention is to transfer carbon lIi fibers consisting of at least 500 single fibers through an impregnated roller with a part of the roller surface exposed] into a noising liquid. 1.
This can be achieved by applying a υ sizing agent to carbon fibers, which is characterized by bringing the yarn into contact with the exposed surface of an impregnating roller and then immersing it in a sizing solution.

Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of a sizing treatment according to the present invention, in which 1 is a yarn to be treated, 2 is a sizing bath, 3 is an impregnating roller (3゛; exposed surface), and 4 is a sizing treatment. The liquid, 5, is passed through a guide roller.

In the sizing process of the carbon fiber yarn of the present invention, the sizing bath 2 is equipped with an impregnating roller 3 with a part of the roller surface 3° exposed from the sizing liquid level as shown in the figure. It rotates freely or is driven to rotate to follow the running speed of the yarn as appropriate.

The carbon fiber yarn 1 continuously supplied from the previous process is immersed in the sizing liquid 4 via a guide roller 5, but the feature of the sizing treatment of the present invention is that the yarn to be treated is soaked in the liquid in advance as shown in FIG. After contacting the impregnating roller surface 3 exposed on the surface, the impregnating roller is immersed in an ising liquid 4.

That is, according to the research conducted by the present inventors, the following two things were found regarding the adhesion spots of the sizing agent during the sizing treatment of carbon fibers.

First of all, carbon fibers inherently have significantly poorer wettability than other types of fibers such as nylon fibers and polyester fibers. For this reason, when a carbon fiber yarn is suddenly immersed in a sizing liquid, the air contained between the single fibers of the yarn is difficult to handle, and most of the air becomes small bubbles in the bath liquid. These air bubbles significantly impair the stability of the emulsion of I nylon fibers, especially in the case of water-dispersed sizing agents.

The emulsion is partially broken, leading to agglomeration or granulation. This result causes spots of adhesion of the sizing agent to the carbon fiber yarn.

The present invention was made based on new knowledge related to such sizing treatment, and in order to remove the air contained in the carbon fiber yarn before immersing it in the sizing solution, the yarn is pre-impregnated with an impregnated roller. Contact with exposed surface 3°. Since the impregnation roller exposure opening 3' is kept sufficiently wet by the liquid film of the sizing agent, the air in the yarn is replaced with the sizing liquid and the air in the yarn is removed. .

The carbon fiber yarn in the present invention is composed of at least 500 single fibers, and if the yarn is smaller than that, there will be little trouble due to air in the yarn in sizing processing.

Further, the impregnating roller 3 must be provided so that a part of the roller surface is exposed above the sizing liquid surface, and the exposed surface 3
The treated yarn before being immersed in the sizing solution is brought into contact with the sizing solution.
The contact time at that time is usually 0.2 seconds or more, preferably 0.
．． It is held for more than 5 seconds. To set such a contact time, an impregnating roller 3 having a roller diameter of about 50 to 500 mmφ is used.

The degree of immersion of the impregnating roller 3 in the bath liquid and the guide roller 5
You may adjust the installation position etc. as appropriate.

Also, the tension of the yarn during sizing treatment is 0.
A CI of 0.05 to 1.0 is preferable, and if it is less than 0.05 g, it will be difficult to replace the air in the yarn with the enriching liquid at the exposed portion of the impregnating roller 3. On the other hand, if it exceeds 1.0 g, the sizing process will fail. New problems such as the occurrence of fluff are likely to occur.

The carbon fiber in d3 of the present invention is acrylic.

Pitch-based fibers were obtained by known methods using various fibers such as lullose-based fibers as precursors. So-called ``carbonized yarn.''

This includes graphitized threads and those with surface oxidation treatment.

The sizing agent is used as an aqueous solution and/or aqueous dispersion, or an organic solvent solution, and is used as a sizing agent to impart cohesiveness to carbon fibers, improve bending resistance and cooling resistance, and Any sizing agent that can provide good composite properties when used as a reinforcing fiber in a composite material can be suitably used, but in particular, an aqueous solution and/or
Alternatively, in the case of an aqueous dispersion system, the above-mentioned foam generation is noticeable and the effect is large.

The sizing agent used as an aqueous solution and/or dispersion can be water-soluble by adding water-soluble resins such as polyalkylene oxide and its derivatives, polyvinylpyrrolidone and its derivatives, polyvinyl alcohol, or various surfactants. Various known resins such as dispersible epoxy resins and unsaturated polyester resins may be used, but the resins are not particularly limited to the above resins. Note that two or more types of these sizing agents may be blended.

In addition, sizing agents used as organic solvent solutions include
For example, glycidyl ether type, glycidyl ester type,
Epoxy resins such as glycidylamine type and aliphatic epoxide type, unsaturated polyester resins, polyamide resins,
Various known resins such as polyimide resin can be used.

Organic solvents for dissolving these small amounts of isting agents include:
Any substance that can stably dissolve the above resin may be used, such as aromatic hydrocarbons such as benzene, toluene, and xylene, ketones such as acetone, methyl ethyl kene, etc.
Examples include halogenated hydrocarbons such as carbon tetrachloride, tricrene, and chloroform, and modified ethers such as cellosolve, which may be appropriately selected depending on the boiling point, ease of industrial handling, etc.

Note that two or more types of organic solvent-based sizing agents may be blended.

The aqueous solution, aqueous dispersion, or organic solvent solution of the sizing agent may be prepared by a conventionally known method depending on the characteristics of the sizing agent, but the bath concentration of the sizing agent is usually 0.5.
The range is from 10% to 10%.

The amount of the sizing agent attached to the carbon fibers varies somewhat depending on the type of sizing agent, but it is generally in the range of 0.2 to 5% by weight based on the weight of the carbon fibers.

[Effects of the Invention] In the sizing treatment of carbon fiber yarn, the present invention involves the complete process of bringing the yarn to be treated into contact with an impregnating roller 3 exposed above the liquid surface, and then immersing it in the sizing liquid 4. By means of the new measures, agglomeration or granulation of the sizing agent emulsion due to air bubbles in the sizing bath is significantly suppressed. Therefore, the adhesion spots of the sizing agent to the carbon fibers are greatly reduced, and this is a remarkable feature in the production of carbon i-fibers, as it can prevent the occurrence of fuzz and thread breakage during subsequent processes, as well as a decrease in adhesion to the matrix. Qin effect.

Hereinafter, the present invention will be specifically explained with reference to Examples.

In this example, the state of generation of air bubbles in the sizing bath, the state of dispersion of the sizing agent emulsion, and the state of yarn breakage during unwinding of the carbon fiber yarn after winding were determined by the following methods.

(1) Condition of generation of air bubbles in the sizing bath Carbon fiber yarn is immersed in the sizing bath shown in Figure 1 or Figure 2, and the liquid level condition after 1 hour is classified as follows. did.

a. State where almost no bubbles are generated on the liquid surface...Qb
, Part of the liquid surface is covered with bubbles... △C1
State in which the entire liquid surface is covered with air bubbles...×(2) Dispersion state of sizing agent emulsion (stability of sizing liquid) Carbon fiber yarn is immersed in the same manner as in item (1) above. , 8
The particle size of the sizing agent emulsion in the sizing solution (5 μg) was photographically measured using an optical microscope (200x magnification) of the bath solution after a certain period of time, and the particle size of the sizing agent emulsion in the sizing agent emulsion before soaking the carbon fibers was 5 times larger. The particles that were aggregated or granulated were counted.

(3) Broken state of carbon fiber yarn after winding when unwinding The carbon fiber yarn was soaked in the same manner as in item (1) above. After 8 hours of treatment, the carbon fibers were rolled up in the usual way.
The frequency of occurrence of yarn breakage when unwinding at a speed of 5 Qm/min using the lengthwise method was measured and expressed as the number of yarn breakages per 100,000 m.

Example 1 100 carbon fiber yarns consisting of 1 to 6000 filaments were sized by being continuously immersed in the noising bath shown in FIG. 1 at a speed of 10 m/min, and wound up in a conventional manner.

At this time, the contact time between the exposed surface of the impregnating roller and the yarn is varied by changing the position of the guide roller 5, and the bubble generation state of the bath liquid and the stability of the bath liquid are checked.

Also, the state of thread breakage during unwinding was investigated. These results are the first
Shown in the table.

The sizing bath liquid used was an aqueous emulsion solution containing 4% resin, and the sizing agent applied to the yarn was about 1%. In addition, the sizing bath has a roller diameter of 400
An impregnation roller with a diameter of mmφ and a roller width of iooomm was used, and the yarn tension was set to 0°2 g per single fiber.

On the other hand, for comparison, a conventional sizing bath shown in FIG. 2 was used, and the results are also shown in Table 1.

Table 1 Example 2 Carbon gaN yarns with different numbers of collapsing filaments are prepared in Figure 1 (
The fibers were sized using the sizing baths shown in the method of the present invention) and in the sizing bath shown in FIG. 2 (conventional method), and the generation of bubbles in the bath liquid, the stability of the bath liquid, and the state of thread breakage during unwinding were examined.

In addition, the contact time between the exposed surface of the impregnating roller and the yarn in the method of the present invention was 1.0 seconds, and other processing conditions were the same as in Example 1.

The results are shown in Table 2.

(Hereafter, margin) Table 2

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a sizing process according to the present invention, and FIG. 2 is a schematic diagram showing a conventional sizing process. 1: Yarn to be treated (carbon fiber) 2: Sizing bath 3: Impregnation roller 3°: Impregnation roller exposed surface 4: Re-raising liquid 5 Ni guide roller

Claims (4)

[Claims] (1) In a sizing method in which a carbon fiber yarn composed of at least 500 single fibers is immersed in a sizing solution via an impregnated roller with a part of the roller surface exposed, the yarn is connected to the exposed surface of the impregnated roller. A method for applying a sizing agent to carbon fibers, which comprises contacting the fibers and then immersing them in a sizing solution. (2) The method of applying a sizing agent to carbon fibers according to claim 1, wherein the contact time between the carbon fiber threads and the exposed surface of the impregnating roller is at least 0.2 seconds. (3) The method according to claim 1, in which the impregnating roller has a roller diameter of 50 to 500 mmφ, in which a sizing agent is applied to the carbon fiber. (4) The method according to claim 1, in which a sizing agent is applied to carbon fibers having a yarn tension of 0.05 to 1.0 g per single fiber.