JPH0529688B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a non-twisted carbon fiber bundle with excellent spreadability, a method for manufacturing the same, and a manufacturing device. [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 are subjected to molding process as thinly spread sheet-like prepregs.
With the diversification and quantitative expansion of applications, such as the lighter weight and higher performance of molded products and their practical use in aerospace applications, the demand for ultra-thin prepregs and uniform thickness has increased. Ultra-thin prepreg like this,
With the increasing demand for uniform thickness, there has been a strong demand for improving the spreadability of the fiber bundles that are the raw material. In general, carbon fibers inherently have extremely good spreadability.
For this reason, when handling it, it tends to become fluffy and has poor workability, so some kind of sizing treatment is normally required. At this time, in order to uniformly apply the sizing agent to the fiber bundle, it is generally applied to the fiber bundle as a sizing solution or dispersion liquid (hereinafter simply referred to as sizing liquid) adjusted to a low concentration, and the solvent is removed in the next drying process. Dry removed. 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, non-contact dryers have a slow drying speed, and by the time the sizing agent develops its shape-retaining ability, the surface tension of the sizing liquid causes the fiber bundles to converge into a round shape. There was a problem in that the sexual performance deteriorated significantly. Therefore, various proposals have been made in the past as techniques for weakening the focusing power of the sizing agent and improving the spreadability of fiber bundles. For example, a fiber bundle is opened by running a cylindrical body while applying vibration in the axial direction (Japanese Patent Application Laid-Open No. 56-43435);
Fiber bundles are spread in a solvent or in a state swollen with a solvent, by continuously pulling the curved base material along the surface while applying tension.
57-56220, 58-1725), the sizing agent to be attached is reduced or removed, and the sizing agent is pressed against the substrate under tension to widen the width (Japanese Patent Application Laid-open No. 184172/1982).
etc. [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 above-mentioned problems of the prior art.
That is, the purpose is to provide a carbon fiber bundle with excellent spreadability, thereby improving the quality and quality of prepreg as well as the workability and productivity of the prepreg 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-mentioned problems of the present invention are as follows: (1) A carbon fiber bundle yarn containing a sizing agent containing polyglycidyl ethers, cycloaliphatic polyepoxides, or a mixture thereof as an essential component. A non-twisted carbon fiber bundle with excellent spreadability whose width (D) to thickness (t) ratio satisfies the following formula. D/t≧15 (2) When applying a sizing agent containing polyglycidyl ethers, cycloaliphatic polyepoxides, or a mixture thereof as an essential component to the untwisted carbon fiber bundle, a sizing liquid was applied. The untwisted carbon fiber bundle is pressed against a hot roll with a tension of 0.1 g/filament or more, and in the expanded state, the weight of the carbon fiber bundle (W ₀ ) and the weight of the sizing liquid (W ₁ ) at the exit of the hot roll are W ₁ /
A method for producing a non-twisted carbon fiber bundle with excellent spreadability, characterized by drying the bundle until it satisfies (W ₀ + W ₁ )≦0.25. (3) A sizing treatment means for untwisted carbon fiber yarn, a hot roll for drying the sized carbon fiber bundle, a wiping cloth for continuously cleaning the hot roll, and a wiping cloth for drying the hot roll. 1. An apparatus for producing a non-twisted carbon fiber bundle with excellent opening properties, characterized by comprising a pressing means. This can be solved by That is, first, as the sizing agent for the fiber bundle of the present invention, sizing agents containing conventionally known polyglycidyl ethers, cycloaliphatic polyepoxides, or mixtures thereof as essential components are particularly preferred. The sizing agent is an epoxy resin-based sizing agent disclosed in Japanese Patent Publication No. 57-49675. Specifically, it is an epoxy resin-based sizing agent containing an epoxy resin, a condensate of an unsaturated dibasic acid and an alkylene oxide adduct of bisphenols, and an alkylene oxide adduct of phenols as essential components. Further, the sizing agent used in the present invention does not contain a polyurethane resin. When polyurethane resin is included, there are problems such as gum buildup on the hot roll and frequent breakage of single yarns. The adhesion amount of this sizing agent is 0.2 to 5% by weight, preferably 0.5 to 2% by weight.
Weight%. Further, the fiber bundle of the present invention is in a substantially untwisted state. That is, a fiber bundle in which carbonization of a carbon fiber precursor and post-treatments such as electrolytic surface treatment have been carried out in a substantially untwisted state, or after carbonization and post-treatment in a suitably twisted state, This is a fiber bundle that has been untwisted prior to sizing. This fiber bundle is usually a single fiber with a fiber diameter of about 3 to 10μ, about 500
It is a bundle of about 50,000 fibers. In the present invention, the ratio of yarn width (D, mm) to thickness (t, mm) of this fiber bundle, D/t, is 15 or more, preferably 30.
It is important to expand the width to ~60 and maintain that state. Here, the yarn width (D, mm) of the fiber bundle is an actual measurement value, and the thickness (t, mm) is calculated by the following formula. Thickness = total number of filaments x single yarn diameter / D / single yarn diameter In the formula, D is the yarn width (actual value, mm). In this case, if D/t is less than 15, the running fiber bundle is likely to rotate in the S or Z direction during the prepreg process of the fiber bundle of the present invention, causing unevenness in the spreadability. Furthermore, since the yarn width is narrow, it is necessary to increase the width expansion ratio in the prepreg process, which causes an increase in the occurrence of fuzz. As described above, the fibers of the present invention can solve the intended problems of the present invention only by keeping D/t within a predetermined range. It goes without saying that the fiber bundle of the present invention includes all conventionally known carbon fiber bundles such as acrylic, rayon, and pitch fiber bundles. Next, an example of manufacturing the fiber bundle of the present invention and an example of the manufacturing apparatus used therein 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, and 7 is a wipe for wiping off the sizing agent adhering to the hot roll surface. 8 is a supply section for the wiping cloth 7; 9 is a nip roll for pressing the wiping cloth 7 against a hot roll; and 10 is a winding section for the wiping cloth 7. After the carbon fiber bundle 1 running under tension is applied with a sizing liquid by the sizing application means 2,
It is guided to a hot roll 4 via a guide roll 3. In this case, the sizing means 2 include 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 to which the sizing liquid has been applied may be directly guided to the hot roll. The carbon fiber bundle introduced into the hot roll 4 is pressed against the hot roll 4 by tension, and at the same time as it is widened, the flat shape of the carbon fiber bundle widened on the hot roll 4 is rapidly dried, and is limited by the sizing agent. Ru. On the other hand, the excess sizing agent adhering to the hot roll 4 is removed by a cleaning means 6, that is, a wiping cloth 7 (for example, cotton cloth) while the hot roll 4 rotates once. 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 on a winding section 10. Although it is desirable to move the wiping cloth 7 in the opposite direction to the rotation direction of the hot roll 4 from the viewpoint of cleaning efficiency, it may be moved in the same direction as the rotation direction of the hot roll 4. The degree of widening 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 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. Specifically, the untwisted carbon fiber bundle to which the sizing liquid has been applied is pressed against a hot roll with a tension of 0.1 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 width of the carbon fiber bundle, but increasing the tension too high will cause fluffing of the carbon fiber bundle and increase equipment costs. I don't like it either. In addition, in areas where wet carbon fiber bundles run, shortening the distance between the guide roll and hot roll, or the distance from the sizing roll to the hot roll, will reduce the convergence of 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 output and the hot roll is set to 1 m.
The length below is 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 the diameter is too small, it may cause fuzz generation or single yarn winding around the roll, so it is preferably about 50 to 500 mmφ, preferably about 100 to 300 mmφ. In order to fix the form of the carbon fiber bundle widened on the hot roll 4, in addition to the above-mentioned thread tension, the distance between the guide rolls and the hot roll, and the roll diameter, the weight of the carbon fiber bundle at the hot roll exit (W ₀ ) and the sizing liquid weight (W ₁ ) is
Drying is performed until W ₁ /(W ₀ +W ₁ )≦0.25 is satisfied. Note that 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 the hot roll at a speed different from the running speed of the carbon fiber bundle (high speed 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 another example of the sizing processing apparatus for untwisted carbon fiber bundles according to the present invention, which uses a hot plate as a drying apparatus. 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 the 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 is widened and simultaneously dried rapidly, so that the widened carbon fiber bundle is flattened on the hot plate 4'. The fiber bundle of the present invention is obtained by fixing the shape with the sizing agent. "Example" The present invention will be specifically described below with reference to Examples. In this example, the spreadability evaluation was performed using a drum winding device shown in FIG.
3 is a resin impregnating tank, 14, 15, 16 are jigoku bars, and 17 is a winding drum) to produce a unidirectional prepreg, and a method of observing the appearance of the prepreg and reading the width of each yarn on the drum was used. there was. Example 1 Using high-strength carbon fiber with 12,000 filaments (unit length weight = 0.8 g), yarn bundle was 3 m/min, tension was 3
Kg/yarn, apply a sizing liquid (sizing liquid to an epoxy resin system with the following composition prepared according to Japanese Patent Publication No. 57-49675), hottrol,
Samples were prepared using a hot plate and the hot air circulation drying method shown in Figure 3 (in the figure, 4'' is a hot air drying chamber). <Composition of epoxy resin sizing liquid> (a) Epicote 828 (Ciel Chemical Products) )
...30 parts by weight (b) Bisphenol A and 2 mol adduct of EO 2 mol maleic acid 1.5 mol sebacic acid 0.5 mol condensate (acid value 55) ...20 parts by weight (c) Polyoxyethylene (70 mol) Styrenated ( 5 moles) Cumilphenol...5 parts by weight (d) Water...45 parts by weight The roll diameter of Hottrol in this example is 100 mmφ.
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 and the residence time in the machine was 2 minutes. The evaluation results of these samples are shown in Table 1.

[Table] Example 2 Using the carbon fiber bundle and hot roll shown in Example 1, samples were produced at a yarn speed of 3 m/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.

[Table] Example 3 Using the carbon fiber bundle shown in Example 1, yarn speed 3
m/min, tension 3Kg/yarn, sizing device~
Samples with different hot roll diameters were prepared with a distance of 0.5 m to the dryer inlet. Table 3 shows the evaluation results of the samples.

[Table] [Effects of the invention] (1) The carbon fiber bundle of the present invention has a ratio of yarn width (D) to thickness (t), D/t, of sizing-treated untwisted carbon fibers.
By specifying the number to be 15 or more, the following effects are achieved. a) Since the fiber bundle has excellent spreadability, the workability of the fiber bundle in the prepreg process is improved, and stable prepreg production becomes possible. b Since the carbon fiber bundle is fixed in width, a new width-expanding device is not required at the prepreg stage. (2) According to the production method and production apparatus of the present invention, the carbon fiber bundle of the present invention with excellent spreadability can be easily produced 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 shape of the carbon fiber bundle after leaving the dryer is widened and fixed, the S of the carbon fiber bundle during the process run is
Alternatively, rotation in the Z direction can be suppressed, and therefore, the spreadability of the obtained carbon fiber bundle is further improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of a sizing processing apparatus for untwisted carbon fiber bundles according to the present invention, and FIG. 2 is a schematic diagram of another example of a sizing processing apparatus for untwisted carbon fiber bundles according to the present invention (hot plate method). , FIG. 3 is a schematic diagram of an example of a sizing processing apparatus using a conventional hot air circulation dryer, and FIG. 4 is a schematic diagram showing a drum winding apparatus used for evaluating the spreadability of carbon fiber bundles. 1; Untwisted carbon fiber bundle, 2; Sizing means, 3, 5; Guide roll, 4; Hot roll,
4': Hot plate, 4'': Hot air drying chamber, 6: Hot roll cleaning means, 7: Wiping cloth for wiping off the sizing agent adhering to the hot roll surface, 8: Supply section for the wiping cloth 7, 9: Wiping cloth Nitz roll pressing 7 onto hot roll, 10;
Winding part of wiping cloth 7, 11; carbon fiber bobbin, 1
2; carbon fiber bundle pulled out from the carbon fiber bobbin; 13; resin impregnation tank; 14, 15, 16; squeeze bar; 17; winding drum.

Claims (1)

[Claims] 1. The ratio of the yarn width (D) and thickness (t) of a carbon fiber bundle containing a sizing agent containing polyglycidyl ethers, cycloaliphatic polyepoxides, or a mixture thereof as an essential component A non-twisted carbon fiber bundle with excellent spreadability that satisfies the following formula. D/t≧15 2 When applying a sizing agent containing polyglycidyl ethers, cycloaliphatic polyepoxides, or a mixture thereof as an essential component to an untwisted carbon fiber bundle, the untwisted carbon fiber bundle is applied with a sizing liquid. The carbon fiber bundle is pressed against the hot roll with a tension of 0.1 g/filament or more, and in the expanded state, the weight of the carbon fiber bundle (W ₀ ) and the weight of the sizing liquid (W ₁ ) at the exit of the hot roll are W ₁ / (W ₀ + W ₁ ) ≦
A method for producing a non-twisted carbon fiber bundle with excellent opening properties, characterized by drying the bundle until it satisfies 0.25. 3. A sizing treatment means for untwisted carbon fiber bundles, a hot roll for drying the sized carbon fiber bundle, a wiping cloth for continuously cleaning the hot roll, and a means for pressing the wiping cloth against the hot roll. An apparatus for producing untwisted carbon fiber bundles with excellent opening properties.