JPH10273820A - Acrylic fiber with excellent adhesion - Google Patents

Abstract

(57) [Abstract] [Object] To provide an acrylic fiber which has excellent adhesiveness particularly to a rubber-based matrix and does not require special treatment and can remarkably enhance its reinforcing effect by ordinary adhesive treatment. It is in. [Structure] An acrylic fiber composed of a polymer containing at least 95% by weight of acrylonitrile is provided with a treating agent containing polyoxyethylene alkyl ester and polyoxyethylene alkyl ether as a main component, and rubber adhesion is pulled out. It can be achieved by an acrylic fiber characterized by being at least 20 kg / cm by the method. further,
The number of oxyethylene repeats of the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether is 8 or more and 16 or less, and the content of the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether in the treating agent is 50% of the total amount of the treating agent. It can be suitably achieved when the amount is not less than% by weight. Further, the object of the present invention can be better attained when the fiber adhesion amount of the treating agent is 0.1% by weight or more and 2% by weight or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic fiber, and more particularly to an acrylic fiber having excellent adhesion to a matrix, particularly a rubber matrix when used as a reinforcing material.

[0002]

2. Description of the Related Art As a method for improving the adhesion between fiber and rubber, for example, Japanese Patent Application Laid-Open No. Hei 7-304879, Japanese Patent Publication No.
No. 7612 or JP-A-6-263888, it relates exclusively to the composition of an adhesive between a fiber and a rubber or a treatment method using an adhesive. A method of introducing a reactive functional group by subjecting a fiber surface to plasma treatment or electrolytic oxidation treatment is mainly reported only for carbon fibers.

There have been few examples of acrylic fibers that have been used as a reinforcing material so far, and no examples have been reported on the adhesion to a matrix.

[0004]

The problem to be solved by the present invention is to provide a fiber-to-matrix fiber for sufficiently exhibiting a reinforcing effect when acrylic fibers are used as a reinforcing material for an organic matrix. It is an object of the present invention to improve the adhesiveness, and particularly has an excellent adhesiveness to a rubber-based matrix, and can remarkably enhance its reinforcing effect by ordinary adhesive treatment without requiring special treatment. To provide acrylic fiber.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
An acrylic fiber made of a polymer containing at least 95% by weight of acrylonitrile is provided with a treating agent containing polyoxyethylene alkyl ester and polyoxyethylene alkyl ether as a main component, and the rubber adhesiveness is reduced by an initial method by a drawing method. This can be achieved by an acrylic fiber having excellent adhesiveness, characterized in that the adhesive strength is 20 kg / cm or more. Further, the number of oxyethylene repeats of the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether is 8 or more and 16 or less, and the content of the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether in the treating agent is the total amount of the treating agent. Is preferably 50% by weight or more. Furthermore, an object of the present invention is to provide a treatment agent in which the fiber adhesion amount
More preferably, the content is 2% by weight or less.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. First,
The acrylic fiber of the present invention having excellent adhesiveness with a rubber-based matrix contains acrylonitrile alone or at least 95% by weight or more, preferably 97% by weight or more of acrylonitrile. A polyacrylonitrile-based polymer produced by copolymerizing one or more saturated compounds can be produced by a known production method such as a wet, dry or dry-wet spinning method. A production method capable of obtaining high strength as disclosed in JP-A-15287 is preferred. That is, using a polymer having a high molecular weight as compared with a polyacrylonitrile-based polymer of a usual acrylic fiber raw material, dissolving in a solvent of the polymer while defoaming under reduced pressure, spinning out the obtained spinning dope, and coagulating. This is a method in which the film is stretched in multiple stages under the condition of a higher temperature in the later step, and then dried under tension at a temperature of 130 ° C. or less. In addition, acrylonitrile is 9
If the amount is less than 5% by weight, the heat resistance and chemical resistance required for the curing and molding steps of the fiber composite material as the final product are insufficient, and the invention cannot be achieved.

[0007] Other ethylenically unsaturated compounds which may be copolymerized include acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, itaconic acid, maleic acid, mesaconic acid, citraconic acid and water-soluble salts thereof. (Alkali metal salt, ammonium salt), allyl alcohol, methallyl alcohol, oxypropion acrylonitrile, methacrylonitrile, α-methylene glutaronitrile, isopropenyl acetate, acrylamide, dimethylaminoethyl methacrylate, vinylpyridine, vinylpyrrolidone, acrylic acid Well-known ethylenically unsaturated compounds such as methyl, methyl methacrylate, vinyl acetate, allyl chloride, sodium methallyl sulfonate and potassium p-styrene sulfonate can be mentioned. The acrylonitrile-based polymer is produced by a general polymerization method such as an aqueous suspension polymerization method and an emulsion polymerization method, and the production technique is not limited.

The acrylic fiber of the present invention is not particularly limited in its mechanical properties, but is generally an inorganic matrix such as cement or mortar, a resin matrix such as epoxy or polyester, or a rubber such as natural rubber or SBR. When used as a fiber reinforcement in a system matrix, it is desirable that the material has high strength. In this sense, the acrylic fiber used as the raw material of the present invention preferably has a tensile strength of 10 g / d or more and a dry heat shrinkage of 5% or less. Tensile strength is 10
If it is lower than g / d, the effect expected as a reinforcing material for the rubber matrix may not be sufficiently exhibited, and if the dry heat shrinkage is higher than 5%, the rubber-based matrix In some cases, the composition shrinks during kneading and vulcanization after being added to the composition, resulting in a decrease in strength. The dry heat shrinkage ratio as used herein means that a fiber bundle of a fixed length (L) is heated at 150 ° C. under no tension.
The rate of change in fiber length when treated for 30 minutes at this temperature. That is, dry heat shrinkage = (L−L ′) / L × 100 (%) where L ′ is the length of the fiber bundle after the heat treatment. When measuring the length of the fiber bundle, a load of 0.1 g / d was applied to the fiber bundle. Further, as the acrylic fiber as a raw material of the present invention, the strength after dry heat treatment at 180 ° C. for 6 hours is preferably 95% or more of the strength of the acrylic fiber before heat treatment. When acrylic fiber that causes a decrease in strength due to heat treatment is used as a reinforcing material for the rubber matrix,
This is because the rubber composition shrinks at the time of kneading, vulcanization, and molding to cause a reduction in the strength of the product, and the object of the present invention may not be sufficiently achieved.

The acrylic fiber is prepared by converting the above-mentioned acrylic polymer into an organic solvent such as dimethylformamide, dimethylacetamide, dimethylsulfoxide and the like, and a rhodanate.
Zinc chloride, dissolved in an inorganic solvent such as nitric acid to prepare a spinning solution, wet, dry, or can be manufactured by dry-wet spinning method, in the case of wet spinning and dry-wet spinning, extruded into the coagulation liquid, It is obtained by washing with water, stretching and drying after coagulation. From the viewpoint of producing a raw material fiber having a high tensile strength, in addition to the above-described multi-stage drawing, it is preferable to select a rodane salt as a spinning solvent, particularly because of the advantage that the coagulated gel yarn becomes homogeneous and the strength is easily increased.

In order to obtain high strength, it is important to orient the entire molecular chain constituting the fiber in the direction of the fiber axis, and it is important that the molecular chain be sufficiently loosened in the spinning dope. It is. It is generally said that a high molecular weight makes it easier to obtain a high-strength fiber.However, if the molecular weight is too high, the solubility in a solvent decreases, making it difficult to prepare a spinning dope or adversely affecting the operability during spinning. It is necessary to adjust the balance from an industrial point of view, but using an acrylonitrile polymer having a molecular weight of about 200,000, the polymer concentration in the stock solution is generally 5 to 1
It is desirable to set it to 5%. Further, if bubbles are present in the spinning dope, they become defects in the fibers and hinder obtaining high strength. Therefore, it is necessary to remove bubbles by means such as defoaming under reduced pressure during or after dissolution of the polymer.

In order to orient the molecular chains in the fiber axis direction, it is necessary to provide stretching during the spinning step, and more severe drawing is required than in the case of general acrylic fibers. In order to withstand this, it is desirable to produce a homogeneous coagulated gel yarn, and therefore it is important to set coagulation conditions so that slow coagulation occurs. Low temperature coagulation conditions are recommended. Also,
The thickness of the coagulated gel yarn also affects the homogeneity of the gel yarn, and is preferably as small as possible unless the yarn breaks. The thickness is preferably controlled to approximately 50 to 300 microns.

Next, a description will be given of the stretching giving the greatest influence on the molecular chain orientation. As the stretching means, it is essential to perform multi-stage stretching under higher temperature conditions as the later steps, and as a preferable embodiment of such multi-stage stretching, stretching with a gel yarn containing a residual solvent, stretching in hot water And dry heat stretching after drying, and, if necessary, stretching in a steam or a high-boiling solvent having a boiling point of 100 ° C. or more. By appropriately combining these means, an acrylic fiber suitable for the raw material fiber of the present invention, preferably having a tensile strength of 10 g / d or more can be produced.

The drying step must be performed under tension because heat relaxation causes a reduction in strength. Also,
In order to maintain the above-mentioned dry heat shrinkage ratio preferably at 5% or less, it is necessary to perform heat setting at a dry heat shrinkage measurement temperature, that is, at a temperature of 150 ° C. or more. If the heat setting temperature is not higher than the drying temperature or the stretching temperature, a sufficient setting effect cannot be obtained.For example, when the dry heat stretching is performed at 150 to 200 ° C., the heat setting temperature may be 200 ° C. or higher. is necessary. However, the heat setting temperature is not limited to a high temperature, and it is preferable to perform the heat setting at an optimum temperature in consideration of the strength level of the obtained fiber, the dry heat shrinkage, and the like. Generally, the highest temperature in the process, that is, 10 ° C. lower than the dry heat drawing temperature when dry heat drawing is employed.
It is desirable that the temperature be as high as possible. In addition, since the heat setting effect is greatly affected not only by the temperature in the setting step but also by the processing time, it is essential to secure a sufficient residence time. In the acrylic fiber of the present invention, when the residence time in the heat setting step is 5 seconds or more, preferably 8 seconds or more, a dry heat shrinkage of 5% or less can be realized.

The acrylic fiber of the present invention having excellent adhesion is
In the manufacturing process, it is obtained by applying a specific component, that is, a treating agent mainly composed of polyoxyethylene alkyl ester and polyoxyethylene alkyl ether, to the surface of the above-mentioned acrylic fiber as a raw material, and the method of applying the treating agent is not particularly limited. Although it is not necessary, it is preferable to pass through the drying step after applying the gel thread after removing the solvent. Good adhesion to the rubber-based matrix can be obtained when applied to dried fibers, but higher adhesion can be obtained when applied to gel yarn. As a method of applying, a method of immersing a fiber bundle as an object to be treated in a tank containing a treatment agent, a method of using a touch roller, a method of spraying a treatment agent on the fiber bundle, and the like can be applied. Also, it is important that the treatment agent penetrates uniformly into the inside of the fiber bundle.

The preferred treating agent is mainly composed of polyoxyethylene alkyl ester and polyoxyethylene alkyl ether, and the number of repeating oxyethylene of the polyoxyethylene alkyl ester and polyoxyethylene alkyl ether is 8 or more and 16 or less. It is recommended that the total content of the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether in the treating agent is 50% by weight or more of the total amount of the treating agent. If the number of oxyethylene repeats of these components is less than 8, volatilization is remarkable in the drying step after application, and the basic unit is deteriorated. Problems such as lowering the image quality. On the other hand, if the number of oxyethylene repeats exceeds 16, it becomes extremely difficult to disperse the aqueous dispersion when it is applied to the fiber, and the use of a large amount of a dispersant necessitates the content of these components as main components to be 50%. It is difficult to set the content to not less than% by weight. When the total content of these components is less than 50% by weight, the amount of components other than polyoxyethylene alkyl ester and polyoxyethylene alkyl ether attached to the fiber surface increases, and the effect of improving the adhesiveness is also reduced. Decrease. The amount of adhesion to the fiber surface is desirably in the range of 0.1% by weight or more and 2% by weight or less. When the amount of adhesion is less than 0.1% by weight, it may be difficult to exhibit sufficient adhesive strength. On the other hand, when the amount exceeds 2% by weight, an excessive treatment agent component may cause adhesion between the matrix and the fiber surface. There is a risk of inhibition. The components other than the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether contained in the treating agent are not particularly limited, but it is preferable to use a general fiber oil having an antistatic effect from the viewpoint of operability in the drying step. . The selection in consideration of volatilization in a dryer, thermal decomposition, etc. is the same as in the case of general acrylic fiber production.

The term "polyoxyethylene alkyl ester" or "polyoxyethylene alkyl ether" as used herein means a compound obtained by adding an alkyl ester or an alkyl ether to polyoxyethylene. Further, “alkyl” in the present invention refers to those having 8 to 20 carbon atoms. If the number of carbon atoms is less than 8, volatilization becomes remarkable when the applied fiber is dried, which causes inconvenience such as generation of tar. On the other hand, when the number of carbon atoms exceeds 20, emulsification dispersibility deteriorates, and it becomes difficult to prepare a treatment liquid.

In the present invention, these polyoxyethylene alkyl esters and polyoxyethylene alkyl ethers are used in combination.
It is preferably in the range of 10 to 10/90, and more preferably in the range of 80/20 to 20/80. The reason for the effect of the combined use is not clear, but when only one of them is used, the initial adhesive strength of 20 kg / cm by the drawing method aimed at by the present invention cannot be achieved.

An excellent reinforcing effect can be obtained when such an acrylic fiber having a polyoxyethylene alkyl ester and a polyoxyethylene alkyl ether component added to the fiber surface is used as a reinforcing material particularly for a rubber matrix. Although the mechanism is not always clear, these components present at the interface between the fiber and the matrix play a role in strengthening the adhesion between the fiber and the matrix, and also facilitate the dispersion of the fiber in the matrix. It is assumed that the strength of the acrylic fiber was exerted effectively.

By integrally adopting the technical means recommended in the present invention as described above, it is possible to obtain an acrylic fiber having high strength and excellent adhesion to a matrix, especially a rubber matrix.

[0020]

The present invention will be described more specifically with reference to the following examples. Unless otherwise specified, "%" and "part" are used on a weight basis.

Example 1 A monomer mixture comprising 97 parts of acrylonitrile and 3 parts of vinyl acetate was subjected to aqueous suspension polymerization using ammonium persulfate as an initiator to prepare a polyacrylonitrile polymer having a weight average molecular weight of 200,000. The polymer thus obtained was dissolved using sodium rhodanate as a solvent to prepare a spinning dope having a polymer concentration of 8%. After filtering this spinning solution, the pore size is 0.15 m.
Dry and wet spinning was performed using a nozzle having a number of holes of 3,000 m. At this time, the distance between the nozzle surface and the coagulating liquid surface is 4 mm. The stock solution temperature during spinning was maintained at 78 ° C., and the coagulation solution was adjusted to a sodium rhodanate concentration of 17% and a temperature of 0 ° C. The gel yarn from the coagulation liquid is stretched twice while washing with deionized water.
Next, stretching was performed 1.5 times in hot water at 85 ° C. and 2.5 times in boiling water. Next, various oil agents listed in Table 1 were applied using a touch roller. The fiber to which the oil agent was applied was then dried by running on a heating roller whose surface temperature was set stepwise from 100 ° C. to 140 ° C. The dried fiber was further heated through a heating roller having a surface temperature set to 170 ° C., subjected to 2.3 times dry heat drawing, and then brought into contact with a heating roller set to a surface temperature of 220 ° C. for 8 seconds and wound up. . The acrylic fiber thus obtained had a tensile strength of 11.8 g / d and a dry heat shrinkage of 3.2%.
In addition, Table 2 shows the oil agent adhesion amount measured by the extraction method. The adhesion amount of the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether component was calculated from the oil agent adhesion amount and the content in the oil agent.

[0022]

[Table 1]

Using a single cord dipping machine, the acrylic fiber was immersed in a treatment liquid consisting of a butadiene / styrene / vinylpyridine copolymer latex and a resorcin / formalin resin. This code is applied to 100 parts of natural rubber, 20 parts of SRF carbon, R
20 parts of EF carbon, 5 parts of bain nour, 2 parts of styrenated phenol, 2.5 parts of stearic acid, 5 parts of zinc white, N
A rubber compound containing 1 part of cyclohexyl-2-benzothiazyl-sulfenamide and 3 parts of sulfur is sandwiched, press-vulcanized at 140 ° C. for 30 minutes, and subjected to a T test (A) described in JIS L1017-1995 which is a drawing method.
Table 2 also shows the results of measuring the initial adhesive strength according to the above method.

[0024]

[Table 2]

From the results shown in Table 2, it can be seen that the oils (A, B) according to the present invention have a higher value than those containing no polyoxyethylene alkyl ester and polyoxyethylene alkyl ether (oils E, F, G). It can be seen that it shows excellent initial adhesive strength. Further, when the number of oxyethylene repeats of the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether is 8 or less (D), the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether give higher initial adhesive strength as compared with the oil agents E, F and G. 20 kg / cm cannot be achieved. Further, it can be seen that even when the content of the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether component in the oil agent is less than 50%, the target level of the present invention is similarly not reached. In the case where the oil component according to the present invention (A, B) is used, if the amount of adhesion to the fiber deviates from the range of 0.1% to 2%, the object of the present invention of 20 kg / cm may not be obtained. Easy to understand. Also, when the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether component are not used together (H, I), the object of the present invention is 20 kg.
/ Cm cannot be obtained.

[0026]

According to the present invention as described above, when acrylic fiber is used as a reinforcing material for an organic matrix,
A technique for improving the adhesion between the fiber and the matrix for sufficiently exhibiting the reinforcing effect has been clarified. In particular, it is possible to provide a high-strength acrylic fiber having excellent adhesiveness to a rubber-based matrix and capable of remarkably enhancing its reinforcing effect by ordinary adhesive treatment without using a special prescription at the time of the adhesive treatment.

Claims (3)

[Claims] An acrylic fiber made of a polymer containing at least 95% by weight of acrylonitrile is provided with a treating agent containing polyoxyethylene alkyl ester and polyoxyethylene alkyl ether as main components. Has an initial adhesive strength of 20 kg /
Acrylic fiber with excellent adhesiveness, characterized in that it is not less than cm. 2. The polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether have an oxyethylene repeating number of 8 to 16 and the treating agent has a content of the polyoxyethylene alkyl ester and the polyoxyethylene alkyl ether in the treating agent. The acrylic fiber according to claim 1, wherein the amount is 50% by weight or more of the total amount of the agent. 3. The treatment agent has a fiber adhesion amount of 0.1% by weight or more,
3. The composition according to claim 1, wherein the content is 2% by weight or less.
The acrylic fiber according to 1.