JPH08284071A - Sizing application to carbon fiber - Google Patents

Abstract

PURPOSE: To prevent thread breaks during a higher-order processing by reducing adhesion amount threads through inhibiting excessive adhesion of a sizing agent to fuzz set areas, etc., by blowing a compressed gas to carbon fiber filaments after applying the sizing agent to the carbon fiber filaments. CONSTITUTION: This method for applying a sizing agent to carbon fiber filaments is to immerse the running carbon fiber filaments 2 in a sizing solution having 0.5-10wt.% concentration and consisting of a urethane resin and an epoxy resin solution or dispersion in a sizing tank through a group of rollers 1 and uniformly apply 0.2-5wt.% sizing agent based on the carbon fiber by blowing compressed gas 5, in 10-48m/sec flow rate, jet from a hole of a compressed gas supplying pipe 4 located >=1cm apart from the running position of the filament 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for applying a sizing agent to carbon fibers.

[0002]

BACKGROUND OF THE INVENTION Carbon fibers are used in various applications due to their excellent mechanical, chemical, electrical properties and weight reduction, for example, structural materials for aerospace such as aircraft and rockets,
It is widely used for sports equipment such as tennis rackets, golf shafts, and fishing rods, and is about to be used in fields such as transportation machinery such as ships and automobiles. By the way, since carbon fibers are inherently rigid and brittle, and have poor bending resistance and scratch resistance, contact with rollers, rubbing with a yarn guide, or time-dependent Fluffing is likely to occur due to rubbing with lure or various bending operations, and sometimes thread breakage may occur. For this reason, the carbon fibers are generally treated with various sizing agents, whereby the carbon fibers are made to have a bundling property, and bending resistance and abrasion resistance are generally improved.

However, if there is fluff before the sizing agent is applied, the sizing liquid excessively adheres to that portion to cause sizing adhesion unevenness, and in particular, in the portion with a large sizing agent adhesion amount, the yarns stick together. Such sticking due to excessive adhesion of sizing is caused by fluffing due to sticking of the sizing agent when unwinding a wound carbon fiber bundle such as a bobbin in a high-order processing step of carbon fiber, and finally thread breakage. The problem arises that it will spread to.

In particular, when the number of yarns is increased in order to improve the productivity of carbon fibers, the spacing between the carbon fiber yarns becomes narrow, and the adjacent yarns are likely to come into contact with each other, which causes fuzz. Therefore, there is a problem that sizing adhesion spots increase and yarn breakage due to the adhesion spots increases. Particularly when a sizing agent having high tackiness is used, such yarn breakage increases.

Regarding the method of applying the sizing agent to the carbon fiber bundle, JP-A-59-36762 proposes that the yarn after application of the sizing agent is subjected to ultrasonic irradiation treatment. However, with the increasing number of yarns, subjecting each yarn to ultrasonic irradiation causes a problem that the equipment cost rises and the manufacturing cost rises.

Further, JP-A-59-36763 proposes that a plurality of grooved rollers used when applying a sizing agent have two or more different shapes.
However, in this method, fluff may be generated due to running of the grooved roller.

[0007]

An object of the present invention is to solve the above-mentioned problems of the prior art, that is, a sizing agent for the fluff portion of a carbon fiber bundle with relatively inexpensive equipment for sizing treatment of carbon fiber. To reduce the excessive adhesion of sizing agent caused by fluff and the adhesion unevenness of sizing agent caused by the sizing liquid film at the time of multi-thread formation, and to reduce fluff and yarn breakage in the subsequent process. It is to prevent the occurrence.

[0008]

The present invention adopts the following constitution in order to achieve the above object. That is, when a sizing agent is applied to the carbon fiber yarn, the carbon fiber yarn is immersed in a sizing agent solution or dispersion, and then a pressurized gas is blown at a flow rate of 20 to 48 m / sec. This is a method for imparting fiber sizing.

The present invention will be specifically described below.

Usually, the carbon fiber yarn is dipped in a solution in which a sizing agent is dissolved in a solvent or a dispersion liquid in which the sizing agent is dispersed in a solvent, and then dried. The feature of the sizing treatment of the present invention is that the sizing agent solution is used. Alternatively, it is to blow pressurized air to the carbon fiber yarn after applying the dispersion liquid. That is, according to the research conducted by the present inventors, the following facts have been found regarding the adhesion unevenness of the sizing agent in the sizing treatment of carbon fibers.

Since carbon fibers are essentially rigid and brittle as described above, fluff is already generated by contact with a roller or the like in the step before the sizing treatment step. When a sizing agent solution or dispersion is applied to the yarn portion where the fluff is generated, the sizing adhesion amount at the fluff generation portion is locally increased, and the fiber bundle is wound up on a bobbin or in a cheese shape to a higher order. When released in the processing step, the yarns stick to each other and the yarn breaks.

In the present invention, in order to prevent the excessive adhesion of the sizing agent caused by the fluff existing in the carbon fiber yarn, a pressurized gas is blown to the yarn after application of the sizing agent solution or dispersion to apply sizing agent. It reduces the spots. By blowing the pressurized gas, the excess sizing agent solution or dispersion adhering to the fluff portion of the yarn is removed, and the variation in the amount of sizing agent attached after drying in the longitudinal direction of the fiber bundle is reduced. As a result, it is possible to prevent the yarns from sticking to each other and prevent the yarns from breaking when the yarns are released.

In the present invention, air is preferably used as the gas used as the pressurized gas, and from the viewpoint of preventing dusts and the like present in the gas from adhering to the yarn, the heated gas removed through a filter. Is preferably sprayed.

The flow velocity of the heated gas is 20 to 48 m /
Second, preferably 25 to 45 m / sec, more preferably 30
˜40 m / sec, and more preferably 35 to 40 m / sec. That is, if the gas flow rate is less than 20 m / sec, the excess sizing liquid in the fluffing part cannot be removed to the extent that excessive adhesion of the sizing agent can be prevented. On the other hand, when the flow velocity exceeds 48 m / sec, due to the flow velocity, the converging property of the yarn is deteriorated, the yarn is broken during winding, and the fluff of the yarn is increased to cause yarn breakage. Here, the flow velocity of the heated gas refers to the actual flow velocity in the immediate vicinity of the treated yarn.

The shape of the nozzle for blowing the pressurized gas is preferably such that a hole is formed in the metal tube in accordance with the yarn path, or a slit-shaped outlet is opened to blow the yarn. The number of outlets and hole spacing may be adjusted according to the number of yarns and yarn paths,
It is preferable that the number of yarns is greater than the number of yarns, and the interval is also narrower than the number of yarns, in order not to create a blind spot of wind flow. The smaller the hole diameter of the air outlet is, the better in order to increase the flow velocity. However, the diameter is preferably in the range of 0.8 to 1.5 mm in order to prevent clogging of the hole due to dust and the like.

Further, it is desirable that the distance from the pressurized gas outlet yarn path is 1 cm or more. That is, if it is less than 1 cm, the sizing agent removed from the yarn by the pressurized gas scatters and clogs the nozzle hole, or fluff excessively containing the sizing agent attached to the yarn blocks the nozzle hole. The sizing adhesion amount of the yarn becomes uneven,
May cause sticking. The distance between the nozzle outlet and the yarn is preferably 1.5 to 3.0 cm in order to keep the pressurized gas flow velocity in the immediate vicinity of the treated yarn at an interval of 1 cm or more. Good to do.

The pressurized gas is preferably blown out from above the treated yarn at a right angle to the yarn advancing direction in terms of the strength of the wind hitting the yarn and the narrowing of the treatment area.

Further, the tension of the yarn during the sizing treatment is from 0.05 to 100 per single fiber from the viewpoint of preventing the generation of fluff due to vibration and fluctuation of the yarn and the prevention of fluff due to excessive tension.
1.0 g is preferred.

Further, according to the present invention, when a plurality of carbon fibers are run in parallel and subjected to sizing treatment, the liquid film of the sizing liquid generated between the adjacent yarns is removed and the sizing adhesion amount between the yarns is removed. Can also be prevented.

The carbon fibers in the present invention are so-called carbonized yarns, graphite yarns obtained by a known method using various fibers such as acrylic, pitch and cellulose fibers as precursors, and those obtained by subjecting these to surface oxidation treatment. Is included.

The sizing agent is used as an aqueous solution or aqueous dispersion, or an organic solvent solution, which imparts a sizing property to the carbon fibers, improves the bending resistance and scratch resistance, and A sizing agent that can obtain good composite material properties when the fiber is used as a reinforcing fiber of the composite material is preferably used, but particularly in the case of an aqueous solution or a water dispersion system, the generation of a liquid film due to the surface tension described above. Is remarkable and the effect is great. Further, in the case of a sizing agent having high adhesiveness, the effect of the present invention is particularly remarkable.

By adding, for example, polyalkylene oxide and its derivative, polyvinylpyrrolidone and its derivative, water-soluble resin such as polyvinyl alcohol, or various surfactants to the sizing agent used as an aqueous solution and / or an aqueous dispersion. Various known resins such as water-dispersible epoxy resin and unsaturated polyester resin can be used.

As the sizing agent used as the organic solvent solution, for example, glycidyl ether type, glycidyl ester type, glycidyl amine type, aliphatic epoxide type epoxy resins, unsaturated polyester resins, polyamide resins, polyimide resins, etc. are known. Various resins are listed.

The organic solvent in which these sizing agents are dissolved may be any solvent which can dissolve the above-mentioned resin in a stable manner. For example, aromatic hydrocarbons such as benzene, toluene and xylene, ketones such as acetone and methyl ethyl ketone, Examples thereof include halogenated hydrocarbons such as carbon tetrachloride, trichlene, and chloroform, and modified ethers such as cellosolve, but are not particularly limited to the above resins. It may be appropriately selected depending on the boiling point and industrial handling. Two or more kinds of organic solvent-based sizing agents may be blended.

Specifically, (A) epoxy resin, (B)
Examples of the sizing agent include a condensate of an unsaturated dibasic acid and an alkylene oxide adduct of a bisphenol and a (C) alkylene oxide adduct of a phenol, and more specifically, (A Examples of the epoxy resin used in 1) include glycidyl type epoxy resins and non-glycidyl type (peracetic acid type) epoxy resins. The glycidyl type epoxy resin is a bisphenol type epoxy resin, for example, obtained by condensation of epichlorohydrin with bisphenols such as bisphenol A, bisphenol F, 2,2'-bis (4-hydroxyphenyl) butane. There is a phenol type, for example, a novolac type phenolic resin reacted with epichlorohydrin, and an ester type, for example, a glycidyl methacrylic acid ester and an ethylenic double bond-containing unit amount. Examples thereof include copolymers with the body (for example, acrylonitrile, styrene, vinyl acetate, vinyl chloride). Examples of the non-glycidyl epoxy resin include cyclic resin epoxy resins, epoxidized butadiene, epoxidized glyceride, and epoxidized soybean oil.

In the condensate of (B), examples of the unsaturated dibasic acid include fumaric acid, maleic acid, citraconic acid, itaconic acid and the like, and the alkylene oxide adduct of bisphenols is described in (A). Alkylene oxides of the mentioned bisphenols (ethylene oxide (EC),
Propylene oxide (PO), butylene oxide (B
O) and the like) adducts (random or block adducts in the case of two or more alkylene oxide adducts).

Component (C) is a monocyclic phenol (phenol having one aromatic ring), for example, phenol, a phenol having one or more alkyl groups, a polyvalent phenol and a polycycle. Phenol (phenol having two or more aromatic rings), for example, phenylphenol, cumylphenol, benzylphenol, hydroquinonemonophenylether, naphthol, bisphenol, monocyclic phenol Alkylene oxide (for example, EO, PO, BO) adduct of a phenol selected from a reaction product (referred to as styrenated phenol) of styrene with styrene (styrene, α-methylstyrene, etc.) (2 In the case of one or more alkylene oxide adducts, there may be mentioned block or random adducts.

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, provided that the bath concentration of the sizing agent is usually 0.5 to 10% by weight. Ranges are preferably used.
The amount of the sizing agent attached to the carbon fibers varies somewhat depending on the type of the sizing agent, but is generally in the range of 0.2 to 5% by weight per carbon fiber.

[0029]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. The number of yarn breakages in this example was obtained by the following method.

30 when the bobbin of the carbon fiber yarn wound up by the usual method is unwound at the speed of 45 m / min by the longitudinal method.
It was expressed as the number of yarn breakage occurrences per 0 yarn.

(Examples 1 to 3) Single fiber fineness is 0.6d,
300 twisted acrylic carbon fiber yarns with 3000 filaments were run in parallel at a yarn running speed of about 10 m / min, and the yarn tension was 0.2 g per single fiber,
Using the sizing tank shown in FIG. 1, after applying an aqueous dispersion containing 3% by weight of an epoxy resin and a urethane resin, a pipe having a diameter of several mm from a pipe several cm away from the yarn, a flow rate of 25, The air temperature was changed to 35 and 45 m / sec, and normal temperature air was blown above the carbon fiber yarn for about 0.5 seconds and wound up in the usual manner. The amount of the sizing agent attached to the obtained carbon fibers was 1.05% by weight based on the weight of the carbon fibers in each case.

Table 1 shows the evaluation results of the thus-obtained 300 carbon fiber yarns, such as the number of yarn breakages at the time of releasing.

(Comparative Examples 1 to 7) The flow velocity of normal temperature air was set to 0,1.
A carbon fiber yarn was wound in the same manner as in Example 1 except that the rate was changed to 0, 15, and 50 m / sec. Table 1 shows the evaluation results of the 300 carbon fiber yarns thus obtained, such as the number of yarn breakages at the time of releasing.

[0034]

[Table 1]

[0035]

INDUSTRIAL APPLICABILITY In the sizing treatment of a carbon fiber yarn, the present invention blows a pressurized gas onto the yarn after the sizing agent is applied, so that the fluff portion and the carbon fiber yarn inherent in the carbon fiber yarn are blown. Since it is possible to suppress the adhesion of yarns due to excessive adhesion of the sizing agent to the fluff aggregates that adhere to the surface, when releasing such yarns from the bobbin, etc., during high-order processing, the adhesion between yarns It is possible to significantly suppress the occurrence of yarn breakage due to

[Brief description of drawings]

FIG. 1 is a schematic side view showing a sizing treatment facility used in an example.

[Explanation of Codes] 1: Roller 2: Treated yarn 3: Sizing liquid 4: Pressurized gas supply pipe 5: Pressurized gas (air)

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[Procedure amendment]

[Submission date] February 27, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Since carbon fibers are essentially rigid and brittle as described above, fluff is already generated by contact with a roller or the like in the step before the sizing treatment step. When a sizing agent solution or dispersion is applied to the yarn portion where the fluff is generated, the sizing adhesion amount at the fluff generation portion is locally increased, and the fiber bundle is wound up on a bobbin or in a cheese shape to a higher order. If it is unwinding in such machining step, fuzz generation
Thread breakage occurs because the yarns in the parts stick together.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

In the present invention, in order to prevent excessive adhesion of the sizing agent caused by the fluff existing in the carbon fiber yarn, a pressurized gas is blown to the yarn after application of the sizing agent solution or dispersion to apply sizing agent. It reduces the spots. By blowing the pressurized gas, the excess sizing agent solution or dispersion adhering to the fluff portion of the yarn is removed, and the variation in the amount of sizing agent attached after drying in the longitudinal direction of the fiber bundle is reduced. Thus, it is possible to prevent sticking yarn each other described above, the yarn breakage during the yarn unwinding can be prevented.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

[0013] In the present invention, pressurized preferably air as the gas used for the pressure gas, from the viewpoint of such as dust present in the gas is prevented from adhering to the yarn, the pressure was removed them through a filter It is preferable to blow a gas.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

Further, the flow rate of the pressurized gas, 20～48M /
Second, preferably 25 to 45 m / sec, more preferably 30
˜40 m / sec, and more preferably 35 to 40 m / sec. That is, if the gas flow rate is less than 20 m / sec, the excess sizing liquid in the fluffing part cannot be removed to the extent that excessive adhesion of the sizing agent can be prevented. On the other hand, when the flow velocity exceeds 48 m / sec, due to the flow velocity, the converging property of the yarn is deteriorated, the yarn is broken during winding, and the fluff of the yarn is increased to cause yarn breakage. Here, the flow rate of the pressurized gas, refers to processing yarns nearest the actual flow rate.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

To the sizing agent used as an aqueous solution or an aqueous dispersion, for example, a polyalkylene oxide and its derivative, polyvinylpyrrolidone and its derivative, a water-soluble resin such as polyvinyl alcohol, or various surfactants is added to disperse the water. Various well-known resins such as epoxy resin and unsaturated polyester resin, which have good properties, can be mentioned.

Claims (1)

[Claims] 1. When applying a sizing agent to a carbon fiber thread, the carbon fiber thread is immersed in a sizing agent solution or dispersion and then a pressurized gas is blown at a flow rate of 20 to 48 m / sec. A method of applying sizing to carbon fiber.