JP2020158903A - Carbon fiber cord for reinforcing polyurethane resin and manufacturing method thereof - Google Patents

Abstract

To provide a carbon fiber cord for reinforcing a urethane resin excellent in bending fatigue resistance and fray resistance, and to provide a manufacturing method thereof.SOLUTION: There is provided a carbon fiber cord for reinforcing a polyurethane resin which is a carbon fiber bundle obtained by plying two or more fiber bundles, wherein a first twist coefficient (TM1) is in a range of 0.5 to 2.0, a final twist coefficient (TM2) is in a range of 0.5 to 2.0, and a resin containing an isocyanate compound as a constituent is adhered. Further, it is preferable that the total fineness of the carbon fiber bundle is 800 to 3600 tex, and that the resin containing an isocyanate compound as a constituent is a resin composed of an isocyanate and an epoxy. In addition, the producing method comprises: subjecting two or more carbon fiber bundles to twisting such that a first twist coefficient (TM1) is in a range of 0.5 to 2.0, and a final twist coefficient (TM2) is in a range of 0.5 to 2.0; impregnating the twisted carbon fiber bundle in a treatment liquid containing a resin containing an isocyanate compound as a constituent; and subjecting the impregnated twisted carbon fiber bundle to heat treatment.SELECTED DRAWING: None

Description

The present invention relates to a carbon fiber cord for reinforcing polyurethane resin, and more particularly to a carbon fiber cord for reinforcing urethane resin having excellent bending fatigue resistance and fray resistance and a method for producing the same.

Polyurethane resin molded products are superior to general elastomer compositions in wear resistance, mechanical properties, dynamic physical properties, solvent resistance, oil resistance, ozone resistance, etc. It is used in a wide range of fields such as industrial parts such as belts, rolls and casters, office automation (OA) equipment parts such as paper feed rolls and copier rolls, as well as sports and leisure goods.

Especially in precision OA equipment, toothed belts are widely used as polyurethane resin molded bodies, but in toothed belts for precision OA equipment, which require a high degree of belt dimensional stability, high modulus is used as the core wire. Reinforcing fiber cords are often used. At present, a toothed belt using a glass fiber cord is relatively excellent in dimensional stability and dimensional stability over time, and is therefore preferably used for a fixed layout between shafts and the like. However, the glass fiber cord has a problem that it is inferior in adhesiveness to the elastomer portion constituting the belt body (Patent Document 1).

On the other hand, in recent years, it is expected that carbon fiber is used as a resin reinforcing fiber instead of glass fiber. This is because carbon fibers have excellent properties such as high elastic modulus, high strength, dimensional stability, heat resistance and chemical resistance. However, since the surface of carbon fiber is relatively inert, the adhesiveness to a matrix such as polyurethane resin is insufficient as it is, and there is a problem that the characteristics cannot be sufficiently exhibited like glass fiber. there were.

As a solution to this problem, a carbon fiber cord in which the surface of the reinforcing fiber is treated with a resorcin, formalin, rubber latex (RFL) adhesive or the like has been proposed for a particularly general-purpose rubber reinforcing application (Patent Document 1-). 3). However, such a carbon fiber cord for general-purpose rubber has a problem that its adhesiveness is inferior when the matrix is made of polyurethane resin.

On the other hand, as another problem, the polyurethane resin molded product containing the reinforcing fibers has a problem that the fibers are frayed on the cut surface when the molded product is once molded and then cut. This problem has been pointed out especially in belt applications, and was more remarkable when urethane was used for the matrix. While the polyurethane resin that constitutes the matrix of the composite is easily deformed, the high-strength reinforcing fibers are not easily deformed following the deformation, and the fibers are exposed from the end face of the composite material and become frayed.

Until now, when the matrix is urethane resin, a carbon fiber cord for reinforcement that sufficiently satisfies the reinforcing effect and fray resistance has not been obtained. Therefore, a carbon fiber cord for reinforcing polyurethane resin that has both of these characteristics has been developed. I was asked.

Japanese Unexamined Patent Publication No. 2004-366654 Japanese Unexamined Patent Publication No. 2014-70296 Japanese Unexamined Patent Publication No. 2011-241502 JP-A-61-215772

The present invention has been made in view of the above background, and an object of the present invention is to provide a carbon fiber cord for reinforcing a urethane resin having excellent bending fatigue resistance and fray resistance, and a method for producing the same.

The carbon fiber cord for reinforcing polyurethane resin of the present invention is a carbon fiber bundle obtained by twisting two or more fiber bundles, having a lower twist coefficient (TM1) of 0.5 to 2.0 and an upper twist coefficient (TM2). Is in the range of 0.5 to 2.0, and is characterized in that a resin containing an isocyanate compound as a constituent is attached. Here, the twist coefficient (TM) is obtained by the following formula.
TM = T × √D / 1150
[However, TM; twist coefficient, T; number of twists (times / m), D; total fineness (tex) of carbon fibers before resin adhesion is shown. ]

Further, it is preferable that the total fineness of the carbon fiber bundle is 800 to 3600 tex, the tensile strength of the carbon fiber cord is 11 cN / dtex or more, and the pull-out adhesive force of the carbon fiber cord is 500 N / 10 mm or more. The resin containing the isocyanate compound as a constituent is preferably a resin composed of isocyanate and epoxy.

Yet another method for producing the carbon fiber cord for reinforcing polyurethane resin of the present invention is to have two or more carbon fiber bundles having a lower twist coefficient (TM1) of 0.5 to 2.0 and an upper twist coefficient (TM2). It is characterized in that it is twisted so as to be in the range of 0.5 to 2.0, then immersed in a treatment liquid containing a resin containing an isocyanate compound as a constituent, and heat-treated. The twist coefficient (TM) here is the same as the above, and is obtained by the following formula.
TM = T × √D / 1150
[However, TM; twist coefficient, T; number of twists (times / m), D; total fineness (tex) of carbon fibers before resin adhesion is shown. ]

Furthermore, the present invention includes a polyurethane resin molded product using these carbon fiber cords for reinforcing the polyurethane resin of the present invention.

According to the present invention, there is provided a carbon fiber cord for reinforcing urethane resin having excellent bending fatigue resistance and fray resistance, and a method for producing the same.

The carbon fiber cord for reinforcing polyurethane resin of the present invention is a carbon fiber bundle obtained by combining and twisting two or more fiber bundles and twisting them, and has a bottom twist coefficient (TM1) of 0.5 to 2.0. The top twist coefficient (TM2) is in the range of 0.5 to 2.0, and a resin containing an isocyanate compound as a constituent is attached.
Here, as the carbon fiber used in the present invention, conventionally known carbon fibers such as pitch type and PAN type can be used, but in particular, a polyacrylic nitrile type PAN type carbon fiber having excellent strength is preferable. ..

Further, the carbon fiber cord for resin reinforcement of the present invention needs to be a carbon fiber bundle obtained by twisting two or more fiber bundles. Here, the fiber bundle after various twists is preferably in the range of 3000 to 72000, and more preferably in the range of 10,000 to 50,000. The total fineness of the fiber bundle is preferably in the range of 200 tex to 4800 tex, more preferably in the range of 800 tex to 3200 tex. The fiber cross-sectional shape, fiber physical properties, microstructure, etc. of each single yarn (filament) constituting the fiber bundle are not particularly limited, but the fact that the cross-sectional shape is circular is that the fiber bundle is adhered in terms of its strong holding. From the viewpoint of physical properties, it is preferable to have fine irregularities. Further, it is also a preferable embodiment that the carbon fiber is pretreated with an epoxy resin, urethane resin or the like in advance after the silk reeling step, the drawing step, the flame resistance treatment, or the carbonization treatment.

The carbon fiber cord of the present invention is composed of fiber bundles twisted in this way, but is a combination of two or more fiber bundles and has a lower twist and an upper twist. It is necessary to use a twisted cord. The untwisting coefficient (TM1) at this time is preferably in the range of 0.5 to 2.0, and particularly preferably in the range of 1.1 to 1.6. The twist coefficient (TM2) at this time is preferably in the range of 0.5 to 2.0, and particularly preferably in the range of 0.8 to 1.8. Further, it is preferable that the lower twist coefficient is larger than the upper coefficient.

Further, as the direction of twisting, it is preferable that the lower twist and the upper twist are in opposite directions. If the lower twist is S twist, the upper twist is Z twist, and conversely, if the lower twist is Z twist, the upper twist is. It is preferably S-twisted. By twisting in the opposite directions in this way, the constituent reinforcing fiber single yarns are lined up in the axial direction of the fiber bundle, and the reinforcing effect can be further exerted.
By satisfying such a range, the resin component such as an adhesive is sufficiently permeated into the fiber cord, and the carbon fiber for reinforcing the polyurethane resin that satisfies the tensile physical properties and the bending fatigue resistance while exhibiting the fray resistance. As a code, it is possible to exert a particularly preferable effect.

In the present invention, it is necessary to further align a plurality of single-twisted (down-twisted) fiber bundle cords and twist (up-twist) in the direction opposite to the single-twisted direction to use as a multi-twisted cord. Therefore, the number of fiber bundles to be combined for twisting is preferably 5 or less, particularly preferably 2. If the number of fiber bundles is too large, the rigid carbon fibers tend to be fluffed due to rubbing or the like during the process.

The twist coefficient (TM1 and TM2) here is a coefficient (TM) derived from the number of twists and the total fineness by the following equation (1).
TM = T × √D / 1150 formula (1)
[However, TM; twist coefficient, T; number of twists (times / m), D; total fineness (tex) are shown. ]

This formula is generally used for spun cotton yarn, K = t / √N (K: twist coefficient, t: twist number t / inch, N: cotton count) with respect to the specific gravity of cotton. Is converted to the specific gravity of carbon fiber, the cotton count is converted to fineness (tex), and recalculated. When the TM is close to 1.0, the single yarn is appropriately tilted in the fiber axis direction to improve the alignment of the fiber bundles, so that the tensile strength is maximized. Further, when the twist coefficient is high, the inclination of the single yarn becomes too large, the single yarn is less likely to receive strain during bending, and the bending fatigue resistance is improved, but the tensile strength tends to decrease. Further, if the twist coefficient is too large, the initial elongation when a small load is applied increases, and the load that can be borne by a slight elongation decreases.

The carbon fiber cord for reinforcing the polyurethane resin of the present invention is a carbon fiber cord in which a resin containing an isocyanate compound as a constituent is attached to such a fiber bundle. More specifically, it is preferable that the carbon fiber cord is focused by a resin containing an isocyanate compound as a constituent, and further, a resin containing an isocyanate compound as a constituent is solid in the outermost layer of the fiber cord with respect to the weight of the fiber. It is preferable that 5 to 8% by weight is adhered in a fractional ratio.
The resin containing the isocyanate compound used in the present invention as a constituent is preferably an isocyanate resin, a polyurethane resin, a urea resin, a crosslinked product of isocyanate and epoxy, or the like.

At this time, the isocyanate compound used in the present invention can be selected from aromatic diphenylmethane diisocyanate, toluene diisocyanate, aliphatic hexamethylene diisocyanate and the like. More preferably, the use of an aliphatic isocyanate is recommended, and the permeability to the inside of the fiber bundle and the adhesiveness to the polyurethane resin are superior. Further, it is preferable to use blocked isocyanate, and it is preferable to use blocked isocyanate using a block body such as dimethylpyrazole block, methylethylketone oxime block, caprolactam block, and more specifically, dimethylpyrazole block hexamethylene diisocyanate is used. Is particularly preferred. It is also a preferred embodiment to use two or more of the above agents in combination.

In the present invention, the above-mentioned isocyanate compound may be used as an isocyanate resin, and it is also preferable to use a urea resin as the resin. Here, the urea resin is a resin obtained by condensing an amine and an isocyanate compound.

The resin containing a particularly preferable isocyanate compound of the present invention as a constituent component is preferably a resin composed of isocyanate and epoxy. In particular, a resin in which an isocyanate compound and an epoxy compound are crosslinked is preferable. When such a crosslinked product is used, a resin is obtained by infiltrating a relatively low molecular weight isocyanate compound and a highly reactive epoxy compound having a relatively low molecular weight into the fiber and then heat-treating the resin. Can be a fiber bundle to which is attached. By such a method, the low molecular weight compound existing inside the fiber bundle is crosslinked to form a resin, so that the single yarn and the single yarn are sufficiently adhered inside the fiber bundle to obtain a strongly bundled fiber bundle. Is possible.

The epoxy compound used here is preferably one in which an epoxy compound having an epoxy group is attached to the fiber surface and the molecular weight can be increased by heat treatment or the like. Specifically, reaction products of polyhydric alcohols such as ethylene glycol, glycerol, sorbitol, pentaerythritol, and polyethylene glycol with halogen-containing epoxides such as epichlorohydrin, resorcin, pis (4-hydroxyphenyl) dimethylmethane, and phenol. -Polyepoxide compounds obtained by oxidizing unsaturated compounds with the reaction products of polyhydric phenols such as formaldehyde resin, resorcin / formaldehyde resin and the halogen-containing epoxides, peracetic acid or hydrogen peroxide, that is, 3,4 -Epoxycyclohexene epoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexene carboxylate, bis (3,4-epoxy-6-methyl-cyclohexylmethyl) adjate and the like can be mentioned.

Of these, when a reaction product of a polyhydrin and epichlorohydrin, that is, a polyglycidyl ether compound of the polyhydrin is used, excellent performance is exhibited. In particular, it is preferable to use an aqueous dispersion of an epoxy compound having a highly water-soluble sorbitol polyglycidyl ether structure. Furthermore, it is possible to use an aqueous dispersion of a blocked isocyanate having an aliphatic hexamethylene diisocyanate (HDI) structure having excellent permeability into the fiber bundle and an epoxy compound having a highly water-soluble sorbitol polyglycidyl ether structure. Especially preferable. More specifically, it is preferable to use dimethylpyrazole block hexamethylene diisocyanate as the blocked isocyanate and to use a sorbitol polyglycidyl ether-based epoxy compound in combination as the epoxy compound. At this time, as the blocked isocyanate, it is also preferable to use an aromatic isocyanate in combination with the aliphatic isocyanate.

In the present invention, it is preferable that the resin containing the isocyanate compound as a constituent component covers the outer periphery of the carbon fiber cord and is also present in the outermost layer. The resin containing an isocyanate compound as a constituent not only functions as a sizing agent for carbon fiber twisted yarn cords, but also functions as an adhesive with a polyurethane resin that becomes a matrix resin in the final molded product, and is stronger. It becomes possible to obtain a molded product.

In the present invention, a carbon fiber cord having a sufficient bending strength is preferable, and in the carbon fiber cord of the present invention having such a sufficient bending strength, each single yarn is sufficiently focused by a resin, and each single yarn is sufficiently focused. Since the original characteristics of the thread are expressed as a group, it exhibits excellent tensile strength and tensile elastic modulus.

On the other hand, if the bending strength is too high, the cord is very hard, so that when it is attached to a mold when manufacturing a polyurethane resin molded body later, the handleability and the like become very poor. It tends to be bent and easily damaged when passing through a mold mounting process or the like, and the tensile properties of the final product tend to be significantly reduced.

In order to obtain an appropriate bending strength of the carbon fiber cord, for example, it is preferable to use a liquid component as a raw material for the polyurethane resin. If the liquid component is too impregnated inside the carbon fiber cord, the carbon fiber cord may be hardly focused. Therefore, it is preferable to impregnate the carbon fiber cord within a range where there is no problem in using the final polyurethane resin molded body. ..

Further, the carbon fiber cord of the present invention preferably maintains a high roundness. If the balance between the lower twist and the upper twist is lost, the roundness tends to decrease. In that case, there is a problem that the difference in bending strength depending on the bending direction becomes large. Further, if the roundness of the carbon fiber cord is low, it is easy to cause a problem that it is difficult to control the pitch between the target cords when winding the core wire around the mold. When the pitch between the carbon fiber cords is disturbed, stress is concentrated only on a part of the core wires during belt operation, which leads to defects such as belt deviation, riding on the pulley flange, and early belt cutting. In particular, when it is used as a transmission belt, which is a main application as a polyurethane resin molded product, and particularly as an OA belt, there is a problem that it becomes difficult to obtain high positioning accuracy due to unstable running such as meandering.

The tensile strength of the carbon fiber cord of the present invention is preferably 11 cN / dtex or more, and more preferably 13 to 18 cN / dtex. When the value of the tensile strength is low, the thermosetting polyurethane resin molded product tends to be unable to be sufficiently reinforced like the conventional polyurethane resin reinforcing fibers such as glass fiber.

The pull-out adhesive force of the carbon fiber cord for reinforcing the polyurethane resin of the present invention is preferably 500 N / 10 mm or more. In particular, it is preferably in the range of 700 to 1000 N / 10 mm. By having such a high adhesive force between the reinforcing carbon fiber cord and the urethane as the matrix resin, it is possible to further improve the dimensional stability of the finally obtained thermosetting polyurethane resin molded product. For example, when the code of the present invention is used for a transmission belt for OA equipment, it is possible to greatly contribute to improving the accuracy of the OA equipment using the transmission belt.

The carbon fiber cord for reinforcing polyurethane resin of the present invention can be obtained by another method for producing the carbon fiber cord for reinforcing polyurethane resin of the present invention. That is, two or more carbon fiber bundles are twisted so that the lower twist coefficient (TM1) is in the range of 0.5 to 2.0 and the upper twist coefficient (TM2) is in the range of 0.5 to 2.0. Next, it is a method for producing a carbon fiber cord which is immersed in a treatment liquid containing a resin containing an isocyanate compound as a constituent component and heat-treated.
The resin containing a carbon fiber bundle or an isocyanate compound as a constituent component used in the production method of the present invention is the same as described above.

The twist before being immersed in the treatment liquid is twisted so that the lower twist coefficient (TM1) is in the range of 0.5 to 2.0 and the upper twist coefficient (TM2) is in the range of 0.5 to 2.0. It is necessary to apply. Further, it is preferable to perform twisting so that the lower twist coefficient (TM1) is in the range of 1.1 to 1.6 and the upper twist coefficient (TM2) is in the range of 0.8 to 1.8, and the lower twist coefficient is higher. It is preferably larger than the top twist coefficient. Further, it is preferable that the lower twist and the upper twist are in opposite directions. In the present invention, by applying such twisting in advance, a resin component such as an adhesive is sufficiently permeated into the inside of the fiber cord, and polyurethane resin reinforcement that satisfies tensile physical properties and bending fatigue resistance while exhibiting fray resistance. It becomes possible to make a carbon fiber cord for use.
The twist coefficient (TM1 and TM2) here is a coefficient (TM) derived from the number of twists and the total fineness by the following equation (1).
TM = T × √D / 1150 formula (1)
[However, TM; twist coefficient, T; number of twists (times / m), D; total fineness (tex) are shown. ]

By the way, there is a method in which the resin is treated in a different order from the production method of the present invention, that is, the carbon fiber bundle in the untwisted state is then twisted, but in that case, the impregnation property of the resin is slightly improved. There is a problem that the roundness of the carbon fiber cord is lowered because the yarn is twisted after being treated with the resin first. Such a carbon fiber cord cannot exert an appropriate effect. Further, if the roundness of the carbon fiber cord is low, it is easy to cause a problem that it is difficult to control the pitch between the target cords when winding the core wire around the mold. When the pitch between the carbon fiber cords is disturbed, stress is concentrated only on a part of the core wires during belt operation, which leads to defects such as belt deviation, riding on the pulley flange, and early belt cutting. In particular, when it is used as a transmission belt, which is a main application as a polyurethane resin molded product, and particularly as an OA belt, there is a problem that it becomes difficult to obtain high positioning accuracy due to unstable running such as meandering.

Further, in the carbon fiber cord for reinforcing polyurethane resin of the present invention, the carbon fiber cord is focused by immersing it in a treatment liquid containing a resin containing an isocyanate compound as a constituent component and then performing heat treatment. The treatment liquid is alcohol. It is preferable that the aqueous treatment liquid contains. Here, the aqueous system means that the main solvent is water, and the alcohol content is preferably 10% by weight or less, particularly preferably 0.01 to 5% by weight of the treatment liquid. The alcohol used in the present invention is not particularly limited as long as it is an alcohol in which a hydroxyl group (-OH group) is bonded to a carbon atom and is in a liquid state at room temperature, but it is a lower alcohol having 5 or less carbon atoms. Is preferable, and isopropyl alcohol, ethanol or methanol is particularly preferable, and isopropyl alcohol is most preferable.

The method of treating the water-based treatment liquid containing alcohol with the twisted fiber cord is not necessarily limited to the type of fiber and the number of twists, and has the effect of facilitating the penetration of the treatment liquid. However, it is most effective in inorganic fibers having high alcohol resistance, and in particular, the carbon fibers of the present invention.

In the production method of the present invention, the adhesive component can be sufficiently impregnated inside the fiber bundle by containing such an alcohol component.
Further, it is preferable that a resin containing an isocyanate compound as a constituent component is attached to the treated cord in an amount of 5 to 8% by weight in terms of solid content with respect to the weight of the fiber. As the resin containing the isocyanate compound as a constituent component, as described above, an isocyanate resin, a polyurethane resin, a urea resin, a crosslinked product of isocyanate and epoxy, or the like is preferable.

In particular, in the production method of the present invention, when an isocyanate resin is used, a method of immersing the fiber bundle in a solution prepared by dissolving the isocyanate compound in an organic solvent such as toluene and then self-crosslinking the isocyanate compound by heat treatment to obtain a fiber bundle. , A method in which a fiber bundle is immersed in an aqueous dispersion of an aqueous blocked isocyanate and then a fiber bundle is obtained by self-crosslinking of an isocyanate compound in which the blocking agent is dissociated by heat treatment is preferable. Furthermore, it is preferable to use an aqueous agent for this workability, and when such an aqueous agent is used, it is preferable to use a blocked isocyanate in combination. By using blocked isocyanate, water reacts with isocyanate only in the process of volatilizing water, so it is possible to suppress the deactivation of functional groups in the previous dipping process, etc., ensuring high physical properties. It becomes possible to do.

It is also preferable that the resin is a crosslinked product of an isocyanate compound and an epoxy compound. In particular, a method in which a treatment liquid composed of a relatively low molecular weight isocyanate compound and a highly reactive epoxy compound having a relatively low molecular weight is once permeated into the fiber and then heat-treated is preferable. By cross-linking from the inside of the fiber bundle in this way, it becomes possible to bond the single yarn and the single yarn inside the fiber bundle and obtain a strongly bundled fiber bundle.

The epoxy compound used in this method is preferably one in which an epoxy compound having an epoxy group is attached to the fiber surface to increase the molecular weight by heat treatment or the like, and in particular, a reaction product of a polyhydric alcohol and epichlorohydrin, that is, Polyglycidyl ether compounds of polyhydric alcohols are preferable because they exhibit excellent performance. In particular, it is preferable to use an aqueous dispersion of an epoxy compound having a highly water-soluble sorbitol polyglycidyl ether structure. Furthermore, it is possible to use an aqueous dispersion of a blocked isocyanate having an aliphatic hexamethylene diisocyanate (HDI) structure having excellent permeability into the fiber bundle and an epoxy compound having a highly water-soluble sorbitol polyglycidyl ether structure. Especially preferable. More specifically, it is preferable to use dimethylpyrazole block hexamethylene diisocyanate as the blocked isocyanate and to use a sorbitol polyglycidyl ether-based epoxy compound in combination as the epoxy compound. As the blocked isocyanate, it is also possible to use an aromatic isocyanate in combination with the aliphatic isocyanate.

As a method of adhering a resin used as a sizing agent to the inside of a fiber sizing body, a multifilament long fiber in which single fibers are gathered, a shape in which a plurality of single fibers are aligned, or a tow-shaped long fiber is used. , A method of impregnating in a tank containing a sizing agent by continuously feeding fibers from a bobbin or a beam creel, a method of adhering by a roller touch method, or a method of spraying and adhering the sizing agent by a spray method. There is a method of making it. Above all, in order to uniformly adhere the resin to the fibers, a method of impregnating the fibers in a tank containing a sizing agent is preferable, and then it is preferable to adjust the adhesion amount to a certain level with a drawing roll.

Further, as described above, in order to impregnate and permeate the sizing agent into the fiber bundle more, a method of dispersing or dissolving the sizing agent in an aqueous marsion or an organic solvent and diluting it is preferable. In particular, as the production method of the present invention, as described above, it is preferable that the treatment liquid is an aqueous treatment liquid containing alcohol. By the way, the treatment liquid in which the sizing agent is dissolved tends to have high viscosity and tends to have insufficient penetration into the fiber bundle. From this point of view, the treatment liquid is an aqueous treatment liquid containing alcohol. Is preferable.

A particularly preferable method for producing the carbon fiber cord for reinforcing polyurethane resin of the present invention is to prepare a water-based treatment agent containing an isocyanate compound as described above and containing alcohol after subjecting the carbon fibers to lower twist and upper twist. This is a method in which a carbon fiber twisted yarn cord is immersed and heat-treated.

In the production method of the present invention, heat treatment is performed after immersion in the treatment liquid, and it is preferable that the heat treatment is used to dry water or the like, which is a dispersion medium of the focusing agent, and sometimes to crosslink by heat treatment. The treatment device is not particularly limited, and a contact type hot roller or the like can be used, but if a non-contact type hot air drying furnace is used, it is easy to work because there is no adhesion or dirt to the device due to the focusing agent. preferable. As a preferable heat treatment condition, a two-step heat treatment is preferable. Specifically, for example, it is preferable to perform drying at a temperature of 80 to 150 ° C. for 60 to 240 seconds, and then heat treatment at a temperature of 180 to 240 ° C. for 60 to 240 seconds.

First, by the first-stage heat treatment, the treatment liquid containing the resin on the surface of the cord and the inside of the cord is diffused inside the fiber cord to dry the moisture. When the treatment conditions are high temperature, the water starts to volatilize shortly after the water is distilled off, so that sufficient diffusion cannot be obtained and the focusing property becomes insufficient. On the contrary, if the temperature is too low, the resin that is insufficiently dried is transferred to the thread guide or the like, and the resin falls off from the cord, so that a sufficient amount of adhesion cannot be obtained. Following this dry heat treatment, the resin is crosslinked by the second stage heat treatment to form a strong film.

The amount of the resin used as the sizing agent adhered is preferably 5 to 10% by weight. If the amount is too small, the filaments of the fiber cord cannot be sufficiently focused, and the strength tends to decrease due to wear between the single yarns, and the fraying property of the polyurethane resin molded product tends to decrease. On the other hand, if the amount is too large, there is a risk that the process passability such as gum-up in the treatment process may decrease. More preferably, it is 6 to 8% by weight. The solid content can be controlled by squeezing with a pressure welding roller, scraping with a scrubber, blowing off with air, suction, or beater. To increase the amount of solids, the immersion time can be increased. This may be done by increasing, improving the solid content concentration in the treatment liquid, dipping a plurality of times, or the like.

In the present invention, a resin containing an isocyanate compound, which is a sizing agent for carbon fiber twisted yarn cords, as a constituent component can also function as an adhesive with a polyurethane resin. Therefore, it is preferable that the resin containing the isocyanate compound as a constituent component is present in the outermost layer, which is abundant up to the outer periphery of the carbon fiber cord.

The carbon fiber cord for reinforcing polyurethane resin obtained by such a manufacturing method of the present invention is a carbon fiber cord for reinforcing polyurethane resin having significantly improved tensile properties, bending fatigue resistance, adhesiveness, and fray resistance. By using the carbon fiber cord for reinforcing polyurethane resin as a reinforcing material, a polyurethane resin molded body having very excellent physical properties can be obtained.

Further, such a carbon fiber cord for reinforcing a polyurethane resin of the present invention can be made into a polyurethane resin molded product by attaching the carbon fiber cord to a mold and molding it. As the polyurethane resin molded product, it is preferable to use a combination of a thermosetting polyurethane resin having more excellent mechanical properties and heat resistance and a carbon fiber cord.

A thermosetting polyurethane resin that is preferable as a matrix resin used in such a polyurethane resin molded product is obtained by casting a liquid raw material and heating and curing it. Then, as a molding method, a one-shot method in which a premix solution in which a polyol, a catalyst, a chain extender, a pigment, etc. are mixed and a solution containing an isocyanate component are mixed, and this is cast and cured, or in advance. A prepolymer method in which isocyanate and a polyol are reacted, a prepolymer in which a part of isocyanate is modified with a polyol and a curing agent are mixed and cast, and a cross-linking reaction is carried out can be adopted. In the present invention, the prepolymer method can be adopted. Is particularly preferable.

The isocyanate used here is not limited, but is preferably an aromatic polyisocyanate, an aliphatic polyisocyanate, an alicyclic polyisocyanate, or a modified product thereof. More specifically, toluene diisocyanate (TDI), methylene diisocyanate (MDI), xylylene diisocyanate (XDI), naphthalenedi isocyanate (NDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and the like can be exemplified. Aromatic polyisocyanates are preferably used, and TDI and MDI are more preferably used.

Examples of the polyol include ester-based polyols, ether-based polyols, acrylic polyols, polybutadiene polyols, and mixed polyols thereof. Examples of the ether-based polyol include polyethylene ether glycol (PEG), polypropylene ether glycol (PPG), and polytetramethylene ether glycol (PTMG), and examples of the ester-based polyol include polyethylene adipate (PEA) and polybutylene adipate (PBA). ), Polyhexamethylene adipate (PHA), poly-ε-caprolactone (PCL) and the like. Among them, polytetramethylene ether glycol (PTMG), which is excellent in moisture resistance and water resistance and can obtain a molded product having tough physical properties and small hysteresis loss, is preferably used.

As the curing agent, amine compounds which are primary amines, secondary amines and tertiary amines are used, and specifically, 1,4-phenylenediamine, 2,6-diaminotoluene, 1,5-naphthalenediamine, 4 , 4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane (hereinafter referred to as MOCA), 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1-methyl-3,5 -Bis (methylthio) -2,6-diaminobenzene, 1-methyl 3,5'-diethyl-2,6-diaminobenzene, 4-4'-methylene-bis- (3-chloro-2,6-diethylaniline) ), 4,4'-Methylene-bis- (ortho-chloroaniline), 4,4'-methylene-bis- (2,3-dichloroaniline), trimethylene glycol di-para-aminobenzoate, 4,4' -Methylene-bis- (2,6-diethylaniline), 4,4'-methylene-bis- (2,6-diisopropylaniline), 4,4'-methylene-bis- (2-methyl-6-isopropylaniline) ), 4,4'-diaminodiphenylsulfone and the like can be used.

In addition to the above components, additives such as plasticizers, pigments, defoamers, fillers, catalysts, and stabilizers can be added to the matrix resin of the molded product. As the plasticizer, generally, dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate (DOA), tricresyl phosphate (TCP), chlorine-based paraffin, dialkyl phthalate and the like can be used.

As the catalyst, an organic carboxylic acid compound which is an acid catalyst is used, and specifically, an aliphatic carboxylic acid such as azelaic acid, oleic acid, sebacic acid, and adipic acid, and an aromatic carboxylic acid such as benzoic acid and toluic acid. Is used. In addition, amine compounds typified by triethylamine, N, N-dimethylcyclohexylamine and triethylenediamine, and organometallic compounds typified by stanas octoate, dibutyltin dilaurate and dioctyltin markaptide are appropriately used.

As a more specific method for producing a thermosetting polyurethane resin molded product using a carbon fiber cord for reinforcing a polyurethane resin, for example, a urethane prepolymer obtained by reacting the isocyanate and a polyol in advance is defoamed as necessary. Add agent, plasticizer, etc. and store at 50-80 ° C. In addition, a liquid in which the curing agent is completely dissolved at an atmospheric temperature of 100 ° C. or higher is prepared in advance. When the catalyst is blended with the polyurethane raw material, it is preferable to stir and mix it with the above-mentioned curing agent in advance.

Next, with the carbon fiber cord wound around the mold in a spiral, the above urethane prepolymer solution and the curing agent solution are stirred and mixed, injected into the mold, and heated under certain conditions to be thermoset. Can be manufactured by For a toothed belt or the like, which is a typical polyurethane resin molded product, it is generally preferable to manufacture a large belt sleeve from the viewpoint of production efficiency, and then cut it to a predetermined width to manufacture the belt.

The carbon fiber cord for reinforcing polyurethane resin thus obtained and the polyurethane resin molded product using the same are excellent in tensile properties, bending fatigue resistance, adhesiveness, and fray resistance, and as a specific example of the polyurethane resin molded product. Can be mentioned as a resin belt.

Hereinafter, the present invention will be described with reference to examples, but the examples are for illustration purposes only, and the present invention is not limited thereto. The evaluation in the examples of the present invention was carried out by the following measurement method.

(1) Cord fineness, cord diameter (cord gauge), tensile strength, tensile elastic modulus (initial tensile resistance)
The measurement was performed according to JIS L1017 (2002).

(2) Pull-out adhesive force of the cord First, about 100 mm of the tip of the carbon fiber cord for reinforcing the polyurethane resin was installed in a mold coated with a mold release agent. After that, 100 parts of the prepolymer obtained by the reaction of tolylene diisocyanate and polytetramethylene ether glycol and 17 parts of the amine-based curing agent (methylenebis (2-chloroaniline) (MOCA)) were charged at predetermined temperatures (main raw material liquid: Heated to 60 ° C., curing agent solution: 120 ° C.), mixed, and vacuum defoamed. The mixed solution after vacuum defoaming was poured into a mold heated to 115 ° C. and cured at 60 ° C. for 24 hours. , A heat-curable polyurethane resin molded body was obtained. After the mold was released, the carbon fiber cord for reinforcing the polyurethane resin was evaluated by the adhesive force when it was pulled out from the heat-curable polyurethane resin molded body.

(3) Strong retention after bending fatigue of polyurethane resin molded body Eight carbon fiber cords for reinforcing polyurethane resin are embedded in a mold having a width of 50 mm, a length of 500 mm, and a thickness of 2 mm at equal intervals, and then (2). Similarly, the thermosetting polyurethane resin raw material was injected into a mold and cured to obtain a flat belt-shaped thermosetting polyurethane resin molded body.
The obtained flat belt-shaped polyurethane resin molded body is attached to a roller having a diameter of 50 mm by applying a load of 30 kg, and is reciprocated at 100 rpm at a roller bending (contact) distance of 100 mm in an atmosphere of 100 ° C. 100,000 times. After repeated bending, the residual strength was measured to determine the strength retention after bending fatigue.

(4) Fraying property The belt-shaped polyurethane resin molded body in which the carbon fiber cord obtained in (2) above was embedded was cut at an angle of 1 ° and exposed on the cross section of the cut portion at the center of the cord. The fraying property was evaluated by visually observing the focused state of the fiber cord and observing it with an optical microscope. The fraying property was evaluated and judged in three stages as follows.
[Fatigue (after flexion fatigue test)]
◯: The filament of the fiber cord is focused, and no abnormality in appearance is observed, which is good.
Δ: Poor focusing is observed on some filaments of the fiber cord.
X: The filament of the fiber cord has a poor focusing and is not focused.

[Example 1]
80 g of a polyepoxide compound having a sorbitol polyglycidyl ether structure (“Denacol EX-614B”, manufactured by Nagase ChemteX Corporation, concentration 100%) and an aqueous solution of dialkyl sulfosuccinate sodium salt (“Neocol SW-C”, as a surfactant). 30 g of Daiichi Kogyo Seiyaku Co., Ltd. (concentration 70%) and 70 g of alcohol (isopropyl alcohol) were added and stirred, and this was stirred and added to 60 g of water to dissolve it. 700.0 g of a condensate of dimethylpyrazole block-HDI trimmer having 3 or more functional groups as an isocyanate compound (“Trixene BI201”, manufactured by Baxenden, UK, concentration 40%) was added with stirring to adjust the solid content concentration. After preparing a dispersion of 40% of the treatment agent, it was diluted with water to obtain a 15% treatment liquid.

One 800tex / 12000 filament carbon fiber (“UTS50”, manufactured by Teijin Limited) is used to perform downward twisting in the Z direction with a twist number of 60 times / m, and the two downward twisted fiber bundles are combined. , The number of twists was 50 times / m, and the upper twist was applied in the S direction to obtain a carbon fiber twisted yarn cord having various twists. This fiber cord is fed at a speed of 5 m / min using a computer processor (CA Ritzler dip cord processor), immersed in the above-mentioned treatment liquid, and then dried at a constant length of 120 ° C. for 120 seconds. Then, heat treatment was performed at a constant length of 235 ° C. for 60 seconds to obtain a carbon fiber cord for reinforcing polyurethane resin.
5.5% by weight of a crosslinked resin containing an epoxy compound and an isocyanate compound as constituents was attached to the carbon fiber cord in terms of solid content with respect to the carbon fiber twisted yarn cord. Table 1 shows the performance evaluation results of the obtained carbon fiber cord and the polyurethane resin molded product produced using the carbon fiber cord.

[Example 2]
The carbon fiber cord was bonded in the same manner as in Example 1 except that the top twist was changed from 50 times / m to 40 times / m. Table 1 summarizes the performance evaluation results of the obtained carbon fiber-treated cord and the polyurethane resin molded product produced by using the carbon fiber cord.

[Example 3]
The carbon fiber cord was bonded in the same manner as in Example 1 except that the top twist was changed from 50 times / m to 30 times / m. Table 1 summarizes the performance evaluation results of the obtained carbon fiber-treated cord and the polyurethane resin molded product produced by using the carbon fiber cord.

[Example 4]
The carbon fiber cord was bonded in the same manner as in Example 1 except that the treatment liquid was changed to 20% instead of the 15% treatment liquid. Table 1 summarizes the performance evaluation results of the obtained carbon fiber-treated cord and the polyurethane resin molded product produced by using the carbon fiber cord.

[Comparative Example 1]
The carbon fiber cords were bonded in the same manner as in Example 1 except that two 800tex / 12000 filament carbon fibers were bundled and twisted in a single twist without performing various twists. Table 1 summarizes the performance evaluation results of the obtained carbon fiber-treated cord and the polyurethane resin molded product produced by using the carbon fiber cord.

According to the present invention, it is possible to provide a carbon fiber cord having significantly improved fraying property, excellent adhesiveness to polyurethane, bending fatigue, and durability, and which is suitably used as a core wire of a transmission belt. In particular, it can be suitably used as a core wire of a friction transmission belt or a toothed belt.

Claims (8)

It is a carbon fiber bundle obtained by twisting two or more fiber bundles, and has a lower twist coefficient (TM1) of 0.5 to 2.0 and an upper twist coefficient (TM2) of 0.5 to 2.0. , A carbon fiber cord for reinforcing a polyurethane resin, characterized in that a resin containing an isocyanate compound as a constituent is attached.
TM = T × √D / 1150
[However, TM; twist coefficient, T; number of twists (times / m), D; total fineness (tex) of carbon fibers before resin adhesion is shown. ] The carbon fiber cord for reinforcing a polyurethane resin according to claim 1, wherein the total fineness of the carbon fiber bundle is 800 to 3600 tex. The carbon fiber cord for reinforcing a polyurethane resin according to claim 1 or 2, wherein the tensile strength of the carbon fiber cord is 11 cN / dtex or more. The carbon fiber cord for reinforcing a polyurethane resin according to any one of claims 1 to 3, wherein the pull-out adhesive force of the carbon fiber cord is 500 N / 10 mm or more. The carbon fiber cord for reinforcing a polyurethane resin according to any one of claims 1 to 4, wherein the resin containing an isocyanate compound as a constituent is a resin composed of isocyanate and epoxy. Two or more carbon fiber bundles are twisted so that the lower twist coefficient (TM1) is in the range of 0.5 to 2.0 and the upper twist coefficient (TM2) is in the range of 0.5 to 2.0, and then isocyanate is applied. A method for producing a carbon fiber cord for reinforcing a polyurethane resin, which comprises immersing in a treatment liquid containing a resin containing a compound as a constituent and heat-treating the mixture.
TM = T × √D / 1150
[However, TM; twist coefficient, T; number of twists (times / m), D; total fineness (tex) of carbon fibers before resin adhesion is shown. ] The method for producing a carbon fiber cord for reinforcing a polyurethane resin according to claim 6, wherein the treatment liquid is an aqueous treatment liquid containing alcohol. A polyurethane resin molded product using the carbon fiber cord for reinforcing the polyurethane resin according to any one of claims 1 to 5.