JPH01292038A - Non-twisted carbon fiber bundle having excellent openability, production of said bundle and apparatus therefor - Google Patents

Abstract

PURPOSE:To obtain the subject fiber bundle having extremely excellent spreading effect and remarkably improved openability, by sizing a non-twisted carbon fiber bundle and drying the sized bundle with a hot-roll drier provided with a cleaning means. CONSTITUTION:A non-twisted carbon fiber bundle is subjected to sizing treatment and then dried with a hot-roll drier (preferably having a roll diameter of 100-300mmphi) provided with a cleaning means to obtain the objective fiber bundle. Preferably, the tension applied to the carbon fiber bundle is >=0.2g/ filament and the distance from the outlet of the sizing apparatus to the hot roll is <=0.5m.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an untwisted carbon fiber bundle with excellent spreadability, a method for producing the same, and a production apparatus.

[Prior Art] Carbon fibers are widely used as reinforcing fibers for plastics. The fiber bundles used for these purposes are impregnated with thermosetting resins such as epoxy resins and unsaturated polyester resins, and then molded into thin, spread sheet-like prepregs. With the diversification and quantitative expansion of applications, such as improved performance and partial practical use in aerospace applications, the demand for ultra-thin prepregs and uniform thickness has increased. Ultra-thin prepreg material like this.

With the increasing demand for uniform thickness, there has been a strong demand for improvement in the spreadability of the fiber bundles that serve as raw materials.

In general, carbon fibers inherently have very good opening properties, and because of this, they tend to become fluffy when handled and have poor workability, so some kind of sizing treatment is usually required.

At this time, in order to apply the sizing agent uniformly to the fiber bundle,
A sizing solution that is generally prepared to a low concentration.

Alternatively, it is applied to the fiber bundle as a dispersion liquid (hereinafter simply referred to as sizing liquid), and the solvent is dried and removed in the next drying step. Conventionally, a non-contact dryer, such as a hot air circulation type dryer, has been used as a means for drying the sizing agent due to the viscosity of the sizing agent and the tendency for fiber bundles to fluff.

However, the drying speed of non-contact dryers is slow, and by the time the sizing agent develops its shape retention ability, the fiber bundles are bundled into a round shape due to the surface tension of the sizing solution, and as a result, the fiber bundles are hardened in that shape. There was a problem in that the value decreased significantly. Therefore, various proposals have been made in the past as techniques for weakening the binding power of the sizing agent and improving the opening properties of fiber bundles. For example, a fiber bundle is opened by running it while applying vibration in the axial direction of a cylindrical body (Japanese Patent Laid-Open No. 56-43435).
The fiber bundle is spread in a solvent or in a state swollen with a solvent by continuously pulling it along the surface of a curved base material while applying tension (Japanese Patent Laid-Open No. 57-56220
JP-A-62-184172), the adhering sizing agent is reduced or removed, and the sizing agent is pressed against the substrate under tension to widen the width (JP-A-62-184172).

[Problems to be Solved by the Invention] However, all of these conventional techniques involve rubbing the fiber bundle, and there is a problem in that when the tension is increased to enhance the fiber opening and width widening effect, the generation of fuzz increases.

The object of the present invention is to solve the problems of the prior art described above.

That is, the purpose is to provide a carbon fiber bundle with excellent spreadability, thereby improving the quality and grade of prepreg as well as the workability and productivity of the pre-preg process. Another object of the present invention is to provide an efficient method for producing the carbon fiber bundle and an apparatus for producing the same.

[Means for Solving the Problems] The above problems of the present invention are as follows: (1) Yarn width (D) of carbon fiber bundle containing sizing agent
, a non-twisted carbon fiber bundle with excellent spreadability, in which the ratio of thickness (1) satisfies the following formula.

□≧15 (2) Sizing treatment is applied to the untwisted carbon fiber bundle,
1. A method for producing a non-twisted carbon fiber bundle with excellent opening properties, which is then dried in a hot roll dryer equipped with a cleaning means.

(3) A device for sizing untwisted carbon fiber yarn; 1. A hot roll for drying the sized carbon fiber bundle; and a cleaning device for the hot roll. Equipment for manufacturing untwisted carbon fiber bundles with excellent fiber properties.

It can be solved by

Specifically, the sizing agent for the fiber bundle of the present invention is, for example, a sizing agent containing conventionally known polyglycidyl ethers, cycloaliphatic polyepoxides, or mixtures thereof as essential components. Among these, a particularly preferred sizing agent is an epoxy resin sizing agent disclosed in Japanese Patent Publication No. 57-49675. The amount of this sizing agent deposited is 0.2 to 5% by weight, preferably 0.5 to 2% by weight.

Further, the fiber bundle of the present invention is in a substantially untwisted state.

That is, a fiber bundle that has been subjected to post-treatments such as carbonization of a carbon fiber precursor and electrolytic surface treatment in a substantially non-twisted state;
Alternatively, it is a fiber bundle that has been carbonized and post-treated in a moderately twisted state and then untwisted prior to sizing treatment. This fiber bundle is usually a collection of about 500 to 50,000 single fibers with a fiber diameter of about 3 to 10 μm. In the present invention, the yarn width (D,
#) and thickness (t, Irm>ratio, D/l) is important to widen to 15 or more, preferably 30 to 60, and maintain that state.

Here, the yarn width (D, #I#l) of the fiber bundle is an actual value, and the thickness (t, s) is calculated by the following formula.

D/Single yarn diameter In the formula, D is the yarn width (actual value, #).

In this case, if D/l is less than 15, the running fiber bundle is likely to rotate in the S or Z direction during the burry preg process of the fiber bundle of the present invention, causing unevenness in spreadability. Furthermore, since the yarn width is narrow, it is necessary to increase the width expansion ratio in the buripreg process, which causes an increase in the occurrence of fuzz.

As described above, the fiber bundle of the present invention can solve the intended problems of the present invention only by keeping D/l within a predetermined range.

Note that the fiber bundle of the present invention is made of a conventionally known acrylic type.

Of course, all carbon fiber bundles such as rayon type and pitch type are included.

Next, an example of manufacturing the fiber bundle of the present invention and an example of a manufacturing apparatus used for its removal will be described with reference to the drawings.

FIG. 1 is a schematic diagram of an example of a non-twisted carbon fiber bundle manufacturing apparatus (sizing processing apparatus) according to the present invention.

In FIG. 1, 1 is a non-twisted carbon fiber bundle, 2 is a sizing means, 3 and 5 are guide rolls, 4 is a hot roll,
6 is a cleaning means for the hot roll; 7 is a wiping cloth for wiping off the sizing agent adhering to the surface of the hot roll; 8
9 is a nip roll that presses the wiping cloth 7 against a hot roll; 10 is a winding portion of the wiping cloth 7;

The carbon fiber bundle 1 running under tension is sized by a sizing means 2
After applying the sizing liquid by the guide roll 3
You will be led to Hot Roll 4 via . In this case, the sizing method 2 is dip type, kiss roll type,
Overflow type.

There are spraying methods, but any method may be used.

Further, the guide rolls 3 and 5 are for extending the contact time with the hot roll 4, and the carbon fiber bundle coated with the sizing liquid may be guided directly to the hot roll.

'The carbon fiber bundle introduced into the hot roll 4 is pressed against the hot roll 4 by tension, and is expanded and simultaneously dried rapidly, so that the flat shape of the carbon fiber bundle expanded on the hot roll 4 is fixed by the sizing agent. be done.

On the other hand, the excess sizing agent adhering to the hot roll 4 is removed by the cleaning means 6 while the hot roll 4 rotates once.
That is, it is removed with a wiping cloth 1 (for example, a cotton cloth 5, etc.). The wiping cloth 7 is supplied from a supply section 8, pressed against the hot roll 4 by a nip roll 9, and after continuously cleaning the hot roll 4, is wound up into a second winding section 10.

Although it is desirable to move the wiping cloth 7 in the opposite direction to the rotational direction of the hot roll 4 from the viewpoint of cleaning efficiency, it may be moved in the same direction as the rotational direction of the hot roll 4.

The degree of width of the carbon fiber bundle on the hot roll 4 is controlled by the yarn tension, the distance between the guide roll and the hot roll, the roll diameter, and the like.

The tension applied to the carbon fiber bundle is desirably set as large as possible without causing yarn damage, in order to increase the focusing effect of the carbon fiber bundle due to the surface tension of the sizing liquid and the degree of expansion of the carbon fiber bundle on the hot roll. .19 g/filament or more, preferably 0.2 g/filament or more. The higher the tension, the more effective the carbon fiber bundle on the hot roll will be, increasing the degree of expansion, but increasing the tension too high will cause fluffing of the carbon fiber bundle and increase equipment costs. I don't like it from any point of view.

In addition, in areas where wet carbon fiber bundles travel, shortening the distance between the guide roll and hot roll, or the distance from the sizing exit to the hot roll, will reduce the carbon fiber bundle due to the surface tension of the sizing liquid. Therefore, the distance between the rolls or the distance between the sizing roll and the hot roll is preferably 1 m or less, preferably 0.5 m or less.

In this case, the smaller the roll diameter, the greater the effect of widening the carbon fiber bundle. However, if it is too small, it may cause fluff or the single thread will be wrapped around the roll.
φ, preferably about 100 to 300 Mr1φ.

The degree of widening of the carbon fibers on the hot roll 4 is determined by the carbon fiber bundle weight at the exit of the hot roll (WQ>, the weight of the sizing liquid (Wl ) is W
If l /W□ +W1≦0.25 is satisfied, the shape of the carbon fiber bundle widened on the hot roll can be fixed.
As a means for drying the remaining solvent, either a contact method or a non-contact method may be employed.

Further, the hot roll speed may be the same speed as the running speed of the carbon fiber bundle, but it is more preferable to move it at a speed different from the running speed of the carbon fiber bundle (high speed 1 or low speed). This makes it possible to more effectively widen the carbon fiber bundle on the hot roll. That is, the hot roll may be actively driven, or a freely rotating roll that does not have a drive system and can be rotated lightly by the tension of the yarn may be used.

Next, another example of the manufacturing apparatus for the fiber bundle of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic diagram of an apparatus using a hot plate as a drying apparatus as another example of the sizing processing apparatus for untwisted carbon fiber bundles according to the present invention.

In FIG. 2, 1 is a non-twisted carbon fiber bundle, 2 is a sizing means, 3 is a guide roll, and 4'' is a hot plate.

The carbon fiber bundle 1 running under tension is applied with a sizing liquid by the sizing application means 2, as in the case of the above-mentioned apparatus example, and then guided to a hot plate 4°. The carbon fiber bundle 1 introduced into the hot plate 4' is pressed against the hot plate 4° by the guide roll 3, and at the same time as it is widened, it is rapidly dried, so that the carbon fiber bundle expanded on the hot plate 4' has a flat form. is fixed by the sizing agent, and the fiber bundle of the present invention is obtained.

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

In this example, the spreadability evaluation was performed using a drum winding device shown in FIG.
．． A unidirectional prepreg was produced using a squeeze bar (15, 16 is a squeeze bar, 17 is a winding drum), and a method was used in which the appearance of the prepreg was observed and the width of each yarn on the drum was read.

Example 1 High-strength carbon fiber with 12,000 filaments (unit length weight = 0.8 g) was used at a yarn speed of 3TIi1. /min, tension 3
A sizing liquid (epoxy resin type) was applied to the 9/thread, and the samples were dried using a hot roll, a hot plate, and the hot air circulation drying method shown in Figure 3 (in the figure, 4'' is a hot air drying chamber). Created.

The hot roll in this example has a roll diameter of 100sφ.

The hot plates had a plate length of 400 mm, the drying temperature was 120° C., and the distance from the sizing device to the dryer entrance was 0.5 m. The drying conditions in the hot air circulation dryer used as a comparative example were 180°C;
Residence time on board was 2 minutes.

The evaluation results of these samples are shown in Table 1.

(Hereinafter, blank spaces) Example 2 Using the carbon fiber bundle and hot roll shown in Example 1, samples were produced at a yarn speed of 3 Trt/min with varying tension and distance from the sizing device to the dryer entrance.

The evaluation results of the samples are shown in Table 2.

(Hereinafter, blank space) Example 3 The carbon fiber bundle shown in Example 1 was used, the yarn speed was 3 m/min, the tension was 3 to 3 / yarn, and the distance from the sizing device to the dryer entrance was 0.5 m, and hot Samples with different roll diameters were produced.

Table 3 shows the evaluation results of the samples.

(Hereinafter, blank space) U Effects of the Invention] (1) The carbon fiber bundle of the present invention is made of sized non-twisted carbon [Ii fiber yarn width (D) to thickness (1) ratio, D/l, of 15 or more. By stipulating this, the following effects will be achieved.

a. Since the fiber bundle has excellent spreadability, the workability of the fiber bundle in the pre-preg process is improved, and stable prepreg production becomes possible.

b. Since the carbon fiber bundle is widened and fixed, a new widening device is not required at the prepreg stage.

(2) According to the manufacturing method and manufacturing apparatus of the present invention, the carbon fiber bundle of the present invention having excellent spreadability can be easily manufactured from the following points.

a. Since the carbon fiber bundle is pressed against the hot roll without the sizing agent drying and hardening, the width widening effect is extremely good.

b. Since the carbon fiber bundle exiting the dryer is widened and fixed, it is possible to suppress the rotation of the carbon fiber bundle in the S or Z direction during the process run, and therefore the opening of the carbon fiber bundle that is 1q Your sexuality will further improve.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of an apparatus for sizing untwisted carbon fiber bundles according to the present invention, and FIG. 2 is a schematic diagram of another example of an apparatus for sizing untwisted carbon fiber bundles (hot plate method) according to the present invention. , FIG. 3 is a schematic diagram of an example of a sizing processing device using a conventional hot air circulation dryer, and FIG. 4 is a schematic diagram showing a drum winding device used for evaluating the spreadability of carbon fiber bundles. 1: Untwisted carbon fiber bundle 2; Sizing imparting means 3.5; Guide roll 4; Hot roll 4'': Hot plate 4'': Also hot air drying chamber: Hot roll cleaning means 7; Sizing agent attached to the hot roll surface A wiping cloth 8 for wiping; a supply section 9 for the wiping cloth 7; a nip roll 10 for pressing the wiping cloth 7 against a real roll; a winding section 11 for the wiping cloth 7: a carbon fiber bobbin 12; Carbon fiber bundle 13; Resin impregnation tank 14, 15.16: Squeezing bar 17: Winding drum

Claims (3)

[Claims] (1) Yarn width (D) of carbon fiber bundle containing sizing agent
, a non-twisted carbon fiber bundle with excellent spreadability, in which the ratio of thickness (t) satisfies the following formula. D/t≧15 (2) Sizing the untwisted carbon fiber bundle,
1. A method for producing a non-twisted carbon fiber bundle with excellent opening properties, which is then dried in a hot roll dryer equipped with a cleaning means. (3) A fiber-spreading method characterized by comprising a sizing treatment means for a non-twisted carbon fiber bundle, a hot roll for drying the sized carbon fiber bundle, and a cleaning means for the hot roll. Excellent equipment for producing untwisted carbon fiber bundles.