JP2009068132A - Fiber, rubber-reinforcing cord and reinforced rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyamide 56 fiber suitable also as a rubber-reinforcing cord, more particularly, the polyamide 56 fiber having a high elastic modulus even after being exposed to heat, excellent in rubber-bonding property, and having a high strength, also provide a rubber-reinforcing cord consisting of the polyamide 56 fiber, and a reinforced rubber containing the rubber-reinforcing cord. <P>SOLUTION: This polyamide 56 fiber has an elongation of 12 to 20% under 4.68 cN/dtex stress after dry heat treatment at 150°C for 30 min. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyamide 56 fiber that has a high elastic modulus even when subjected to a dry heat treatment and is excellent in adhesiveness to an adhesive or rubber. The present invention also relates to a rubber reinforcing cord using the polyamide 56 fiber, and a reinforcing rubber including the reinforcing cord.

  Recently, with the increasing awareness of the environment on a global scale, the development of non-petroleum-derived fiber materials is eagerly desired. Since conventional general-purpose plastics use petroleum resources as the main raw material, global warming caused by petroleum resources being depleted in the future and mass consumption of petroleum resources has been taken up as major problems.

  By using plant resources that grow by taking in carbon dioxide from the atmosphere as a raw material, it can be expected that global warming can be suppressed by the circulation of carbon dioxide, and the problem of resource depletion may be solved. Therefore, in recent years, attention has been focused on plastics starting from plant resources, that is, plastics derived from biomass (hereinafter referred to as biomass plastics). For example, as a representative of biomass plastics, research and development of aliphatic polyesters such as polylactic acid are active, but various properties such as mechanical properties and heat resistance are compared to conventional polyester fibers or polyamide fibers. It was low and the use was considerably limited.

  For example, there is a rubber reinforced cord as an application in which a large amount of synthetic fiber is used and high durability is required. Above all, the tire cord market is extremely large. It is expected to replace the synthetic fiber used for such a large-scale application with biomass plastic. As a rubber reinforcing cord, a cord made of polyamide or polyester is used because it is excellent in balance with the above characteristics. In recent years, further improvement in cord characteristics has been demanded.

  For example, a tire cord made of polyamide is characterized by good rubber adhesion, but further improvement in rubber adhesion is desired. This is because the rubber is reinforced only after the tire cord and the rubber are sufficiently bonded and integrated, and the following can be cited as the merits of improving the adhesion. One is that the number of cords used per unit volume can be reduced and the total weight of the tire can be reduced. The other is that the high adhesiveness suppresses the deterioration of the adhesiveness over time in the actual use environment of the tire and can improve the durability of the tire.

  Further, the rubber reinforcing cord is required to have a high elastic modulus and a high strength. The higher the elastic modulus is, the higher the elastic modulus of the reinforced rubber is, and a reinforced rubber that is less likely to change in size due to external force can be obtained. As an index of elastic modulus, generally, the elongation at the time of 2.34 cN / dtex stress of a rubber reinforced cord is used, and the lower the value, the higher the elastic modulus. Further, a high strength is required, and a high strength can provide a reinforced rubber that is not easily destroyed even when repeatedly deformed.

  However, the rubber reinforcing cord is heated in a process of vulcanization after being embedded in rubber or in an actual use environment. In general, when a rubber reinforcing cord made of synthetic fiber is exposed to heat, its rubber adhesiveness, elastic modulus, and strength tend to decrease. Since this tends to reduce the reinforcing effect, there is a demand for a rubber reinforced cord that does not easily decrease rubber adhesion, elastic modulus, and strength even after being exposed to heat.

  And since a rubber reinforcement cord is excellent in these characteristics in a well-balanced manner, the resulting reinforcement rubber is hardly deformed by an external force. Even if an external force is repeatedly applied, the cord is less likely to fatigue in the rubber.

  As described above, the required characteristics of rubber reinforced cords are diverse, and high characteristics are desired for any required characteristics. Therefore, replacement with general-purpose biomass plastics has been difficult.

  By the way, the applicant has proposed polypentamethylene adipamide (polyamide 56) obtained by heat polycondensation of 1,5-diaminopentane produced by using biomass and adipic acid as a new biomass plastic. (See Patent Document 1). By the technique of Patent Document 1, a polyamide 56 resin having good heat resistance, melt storage stability, and stretchability can be obtained. The polyamide 56 fiber obtained by melt spinning and stretching the resin has good heat resistance, mechanical properties, etc., and is expected to be applied to applications that were difficult to enter with conventional biomass plastics. When exposed to heat, the fiber easily contracts, and the fiber after contraction tends to have a low elastic modulus.

A filament made of polyamide 56 has also been proposed (Patent Document 2). According to the technique of Patent Document 2, it is described that the polyamide 56 is excellent in transparency and has high strength, so that it is suitable for fishing lines and the like. However, the fiber shrinks when exposed to heat. The fiber after shrinkage was easy to have a low elastic modulus. For this reason, although it is suitable for uses such as fishing line, its use in applications exposed to heat has been limited.
JP 2003-292612 A (Claims) JP 2006-144163 A (Claims)

  It is an object of the present invention to provide polyamide 56 fibers that are also suitable for rubber reinforced cords. More specifically, it is to provide a polyamide 56 fiber that does not easily shrink even when exposed to heat, maintains a high elastic modulus, has high strength, and is excellent in rubber adhesion. And it is providing the rubber reinforcement cord which consists of this polyamide 56 fiber, and the reinforcement rubber containing this rubber reinforcement cord.

  As a result of intensive studies on the polyamide 56 fibers suitable for rubber reinforcement cords by the present inventors, the polyamide 56 fibers obtained by a specific production method are hardly shrunk even when subjected to dry heat treatment, and have a high elastic modulus. It turns out to be a rubber reinforced cord that is maintained. It has been found that, for the first time, the excellent rubber adhesiveness of polyamide 56 can be utilized due to the difficulty of shrinkage in the dry heat treatment, and the rubber adhesiveness superior to that of polyamide 66 is exhibited. This succeeded in forming a reinforced rubber having a small dimensional change due to external force. Furthermore, since the rubber-reinforced cord has a high elastic modulus after dry heat treatment and is excellent in rubber adhesiveness, and has high strength, the synergistic effect of these results in a rubber-reinforced cord excellent in fatigue resistance. I found out.

  That is, the first invention of the present invention is a polyamide 56 fiber characterized in that the elongation at the time of 4.68 cN / dtex stress measured after a dry heat treatment at 150 ° C. for 30 minutes is 12 to 20%.

  The second invention is a rubber reinforcing cord made of the above-mentioned polyamide 56 fiber.

  The third invention is a reinforced rubber comprising the above rubber reinforced cord.

  Since the polyamide 56 fiber of the present invention is made of polyamide 56 which is a biomass plastic, it is excellent in environmental adaptability, has high elasticity even after being exposed to heat, has excellent rubber adhesion, and has high strength. In particular, it is suitably used as a fiber constituting a rubber reinforcing cord. It is also suitably used as a fiber for various industrial materials. For example, it is preferably used as a fiber constituting a vehicle interior material or a safety part of an automobile, an aircraft, etc., and examples thereof include an airbag, a seat belt, a seat, and a mat. It is also suitable for applications requiring high strength and high elastic modulus, such as fishing nets, ropes, safety belts, slings, tarpaulins, tents, braids, curing sheets, canvas, and sewing threads.

  The rubber reinforced cord made of the polyamide 56 fiber has an excellent reinforcing effect and fatigue resistance, and therefore can be used for a wide variety of reinforced rubber. For example, rubber reinforced cords suitable for a wide range of applications, such as tires for passenger cars, trucks, motorcycles, aircraft, etc., rubber belts and rubber hoses for automobiles and general materials, and reinforced rubber can be obtained.

  The polyamide 56 fiber of the present invention is a fiber made of polyamide 56 resin having 1,5-diaminopentane and adipic acid as main structural units. The polyamide 56 fiber of the present invention is preferable because it contains 1,5-diaminopentane units utilizing biomass and is excellent in environmental adaptability. In view of more excellent environmental adaptability, 50% or more of the 1,5-diaminopentane units constituting the polyamide 56 are preferably made of 1,5-diaminopentane obtained by using biomass. More preferably, it is 75% or more, and most preferably 100%.

  The polyamide 56 resin may be a copolymer obtained by copolymerizing a small amount of other monomers within a range that does not impair the object effect of the present invention. It is preferable that the content of the copolymer component is low because the elongation at the time of .68 cN / dtex stress is low and the excellent adhesiveness of the polyamide 56 is easily utilized. Further, in order that the rubber reinforcing cord of the present invention is more excellent in environmental adaptability, the content of the copolymer component is preferably low, and the content of the copolymer component in the polyamide 56 is 5 mol% or less. Preferably, it is 3 mol% or less, more preferably 1 mol% or less. Similarly, the polyamide 56 resin may be a mixture of other polymers within a range that does not impair the object effects of the present invention. However, the higher the crystallinity of the polyamide 56 resin is, the more preferable it is. The content is preferably low, preferably 30% by weight or less, more preferably 10% by weight or less, and still more preferably 5% by weight or less.

  The fiber of the present invention has a thin and long form and may be a long fiber or a short fiber, but is preferably a long fiber in terms of becoming a fiber having a higher elastic modulus. And it is preferable that the fiber which comprises a rubber reinforcement cord is a multifilament. By using a multifilament, it is possible to impart an appropriate flexibility to the cord.

  The total fineness of the polyamide 56 fiber of the present invention is preferably 250 to 5,000 dtex. It is preferable that the total fineness of the polyamide 56 fiber is 250 dtex or more because the strength of the polyamide 56 fiber is increased and a change in physical properties in a high-order processing step can be suppressed. More preferably, it is 300 dtex or more, More preferably, it is 350 dtex or more. Further, it is preferable that the total fineness of the polyamide 56 fiber is 5,000 dtex or less because a rubber-reinforced cord excellent in adhesion can be obtained because the adhesive can be easily applied uniformly. More preferably, it is 4,000 dtex or less, More preferably, it is 3,000 dtex or less.

  The single fiber fineness of the fibers constituting the multifilament is preferably in the range of 1 to 50 dtex. By being 1 dtex or more, the moisture absorption from outside the system of the polyamide 56 fiber can be reduced as will be described later, the orientation crystallization of the fiber is promoted in the fiber production process, and 4.68 cN / dtex after the dry heat treatment. This is preferable because it is easy to obtain fibers having low elongation under stress. Moreover, since it becomes a fiber with high intensity | strength, it is preferable. More preferably, it is 3 dtex or more, More preferably, it is 5 dtex or more. Moreover, when it is 50 dtex or less, the fiber has appropriate flexibility, and the resulting rubber-reinforced cord is not easily fatigued by stretching or compression, which is preferable. More preferably, it is 40 dtex or less, More preferably, it is 30 dtex or less.

  The cross-sectional shape of the single fiber of the polyamide 56 fiber of the present invention can adopt not only a round cross-section but also a wide variety of cross-sectional shapes such as flat, Y-type, T-type, hollow-type, rice-type, well-type, A round cross section is preferable in that the strength of the polyamide 56 fiber is increased.

  The polyamide 56 fiber of the present invention needs to have an elongation at the time of 4.68 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes of 20% or less (hereinafter simply referred to as 4.68 cN / d after dry heat treatment). It may be described as elongation at dtex stress). The reason why it is important that the polyamide 56 fiber has a low elongation at 4.68 cN / dtex stress after the dry heat treatment is described in detail later. Even after being made, the rubber reinforcing cord formed from the polyamide 56 fiber having a high modulus of elasticity of 20% or less at the time of 4.68 cN / dtex stress has an excellent reinforcing effect, rubber adhesion, This is preferable because fatigue is exhibited.

  Here, the outline of the measuring method of the elongation at the time of 4.68 cN / dtex stress after the dry heat treatment at 150 ° C. for 30 minutes will be described. Detailed information on measuring instruments and the like is described in the examples.

  First, the elongation at the time of 4.68 cN / dtex stress is JIS L1017 (1995), elongation at constant load of 7.7, (1) SS curve measured according to the measurement method of the standard time test. The elongation at a constant load. In the case of fibers, the elongation at the time of 4.68 cN / dtex stress was used as an index of elastic modulus, and in the case of the cord, the elongation at the time of 2.34 cN / dtex stress was used as an index of elastic modulus. Here, since the polyamide 56 fiber is a hygroscopic fiber as described later, the SS curve changes due to moisture absorption by the temperature and humidity environment. Therefore, it is necessary to condition the fiber under certain conditions and perform SS measurement under the same conditions before SS measurement. In the present invention, the object to be measured was sampled in the shape of a cake and left for 48 hours in an environment of 25 ° C. and RH 55% with no load, and then the SS curve was measured in the same temperature and humidity environment. In addition, after performing humidity control of fiber at 25 degreeCRH55% before SS measurement, about measuring SS curve under the same temperature humidity environment, it is 4.68 cN / dtex stress of unheat-treated fiber. The same applies to the measurement of elongation, strength, and elongation.

  Dry heat treatment at 150 ° C. for 30 minutes is performed by the following method. First, a polyamide 56 fiber loop-shaped casserole is prepared with a measuring machine, and the casserole is suspended in an oven preheated to an atmospheric temperature of 150 ° C. in an unloaded state and subjected to a dry heat treatment. Then, after 30 minutes have passed since the casserole was inserted, the casserole is taken out. As described above, the husk was conditioned for 48 hours in an environment of 25 ° C. and RH 55% under no load as described above, and then S—S measurement was performed in the same environment to obtain 4.68 cN / dtex. The elongation at the time of stress was defined as the elongation at the time of 4.68 cN / dtex stress after the dry heat treatment at 150 ° C. for 30 minutes.

  Here, the reason why the fiber having a high elastic modulus after the dry heat treatment is suitable as the fiber constituting the rubber reinforcing cord will be described in detail. After the rubber reinforcing cord is embedded in the rubber, it is exposed to a high temperature of 130 to 180 ° C. in a process of vulcanizing the rubber. In the case of a tire, the surface temperature may be heated to 130 ° C. or higher during high-speed running, and the tire is exposed to heat in the vulcanization process and actual use environment. At this time, in the synthetic fibers constituting the cord, the oriented amorphous chains tend to relax over time, and the elastic modulus of the cord tends to decrease (the elongation of the cord at the time of 2.34 cN / dtex stress). Will be bigger). When the elastic modulus of the cord is lowered, the reinforcing rubber is easily deformed by an external force. For example, when used as a tire, the running stability is deteriorated. Further, since the reinforcing rubber is easily deformed by the force, the cord tends to be easily fatigued in the reinforcing rubber. From the above, it is important to keep the elastic modulus of the rubber-reinforced cord high even after being exposed to heat.

  However, as shown in FIG. 1, in the conventional polyamide 56 fiber (Comparative Examples 1 to 3), no matter how high the elastic modulus cord is formed by means of changing the stretch stress in the cord manufacturing process, the elasticity of the cord As the rate increases (the elongation at the time of 2.34 cN / dtex stress decreases), the dry yield increases. Therefore, when the dry heat treatment is performed, the elastic modulus decreases. Since the relationship between the elastic modulus of the rubber reinforced cord made of the same fiber and the dry yield is substantially constant, it has been found that the elastic modulus after the dry heat treatment is almost constant. For this reason, a rubber reinforcing cord made of a conventional polyamide 56 fiber cannot exhibit a sufficient reinforcing effect. Furthermore, it has also been found that cords made of conventional polyamide 56 fibers have a high dry yield and have not made full use of the excellent adhesion of polyamide 56 fibers described later. For this reason, the present inventors went back to the manufacturing process of the polyamide 56 fiber and studied in detail.

  First, as a result of examining the characteristics of the polyamide 56 fiber that is a precursor of the rubber reinforcing cord, the polyamide 56 fiber is easily shrunk when subjected to a dry heat treatment in a relaxed state (large yield), and 4.68 cN / after the dry heat treatment. It has been found that the elongation at the time of dtex stress is a fiber exceeding 20%. It was found that the rubber reinforced cord obtained due to this was also easily shrunk by the dry heat treatment and the elastic modulus was easily lowered. That is, in order to be a polyamide 56 fiber that is suitably used for rubber reinforcement, it has been a problem to obtain a polyamide 56 fiber having a high elastic modulus even after dry heat treatment.

  The reason why the polyamide 56 fiber is easily shrunk by dry heat treatment and the modulus of elasticity is liable to be lowered is not clear, but it is presumably due to the characteristics of low crystallinity and high hygroscopicity due to the molecular structure of the polyamide 56. . That is, even if the molecular chains in the fiber are highly oriented in the melt spinning process and the drawing process, oriented crystallization is unlikely to occur. Therefore, the obtained fiber is not restricted by the crystalline phase, and has a high mobility amorphous chain. It will contain a lot. Therefore, it was estimated that when exposed to heat, the oriented amorphous material relaxes easily and the fiber contracts, and the elastic modulus decreases.

  The first factor of the low crystallinity of the polyamide 56 fiber is presumed to be due to the regularity of the position of the amide bond in the polyamide 56 molecular chain. For example, in the case of a polyamide such as polyamide 66 in which the number of carbon atoms of diamine is the same as that of dicarboxylic acid n (m = n), the molecular chain is repeated with a pair of m carbon atoms and one amide bond. Therefore, when molecular chains are aligned, amide bond positions are aligned between adjacent molecular chains, and orientational crystallization is likely to occur. However, in the case of polyamides with different diamine carbon number m and dicarboxylic acid carbon number n, such as polyamide 56 (m ≠ n), amide bonds are formed between adjacent molecular chains even if the molecular chains are oriented in the fiber axis direction. Are difficult to align. For this reason, oriented crystallization hardly occurs in the polyamide 56 as a molecular structure.

  Furthermore, in addition to the low crystallinity of the molecular structure, it is also highly hygroscopic as will be described later, so that when it is made into fibers, it becomes difficult to further crystallize it. That is, the fiber has a large specific surface area, and water is easily taken into the amorphous chain in the fiber in the melt spinning process and the drawing process. Therefore, the highly hygroscopic polyamide 56 fiber absorbs a lot of water. The water molecules taken in the fibers enter between the polyamide 56 molecular chains, and the hydrogen bonding force between the molecules is weakened. This makes it difficult for the stretching stress to be uniformly applied to all the molecular chains, and as a result, it is difficult to uniformly orient the amorphous chains, so that the fibers tend to have amorphous chains that do not lead to oriented crystallization.

  Next, the high hygroscopicity of the polyamide 56 will be described. Hygroscopicity is considered to increase as more binding sites with high hydrophilicity exist, and in the case of polyamide, an amide bond corresponds to a binding site with high hydrophilicity. Since the number of amide bonds per unit volume of polyamide 56 is higher than that of conventional polyamide 66, it is a polymer having a high hygroscopicity as a molecular structure (concentration of amide bond calculated from molecular structure polyamide 66: about 8800 eq / ton Polyamide 56: about 9400 eq / ton). Although depending on the internal structure of the fiber and the temperature and humidity conditions, the polyamide 56 has a moisture absorption amount about 1.5 to 3 times higher than that of the polyamide 66 due to the large number of amide bonds per unit volume. And as described above, the high hygroscopicity is an obstacle to orientation crystallization.

  As described above, the polyamide 56 has characteristics of low crystallinity and high hygroscopicity as a molecular structure, and these characteristics are easily manifested when fiberized. For this reason, it has been found that the conventional polyamide 56 fiber is a fiber with insufficient orientation crystallization and has a high dry yield, so that the degree of amorphous orientation during dry heat treatment is greatly reduced.

  And as a result of intensive studies aimed at reducing the elongation at the time of 4.68 cN / dtex stress after the dry heat treatment of the polyamide 56 fiber by the present inventors, a specific production method described later was adopted, and much in the fiber. By forming the oriented crystal phase, the polyamide 56 fiber having a high modulus of elasticity of less than 20% at the time of 4.68 cN / dtex stress even after a dry heat treatment at 150 ° C. for 30 minutes was obtained for the first time. . The polyamide 56 fiber can constitute a rubber reinforced cord having a high elastic modulus even after dry heat treatment for the first time. Further, the polyamide 56 fiber yielded a cord with low dry yield, and it was also possible to sufficiently exhibit the excellent rubber adhesion of the polyamide 56. That is, the excellent rubber adhesiveness of the polyamide 56 is sufficiently exhibited by suppressing adverse effects such as the heat shrinkage force of the cord being concentrated on the bonding interface in the vulcanization process. As a synergistic effect of having a high elastic modulus after dry heat treatment and excellent rubber adhesiveness, a rubber was efficiently reinforced and a reinforced rubber having a small dimensional change due to external force was obtained.

  In addition to these, the rubber reinforced cord of the present invention has high strength, and is strong even after heat treatment, so that it is found that the internal rubber reinforced cord is not easily fatigued even if the reinforcing rubber is repeatedly deformed. It was.

  The lower the elongation at the time of 4.68 cN / dtex stress after the dry heat treatment, the more preferable is a rubber reinforcing cord having a higher reinforcing effect, which is preferable, more preferably 19% or less, still more preferably 18% or less, and particularly preferably. Is 17% or less, with 16% or less being the best. The lower the elongation at the time of 4.68 cN / dtex stress after the dry heat treatment, the better. However, 12% or more is the production limit.

  The polyamide 56 fiber preferably has an elongation at the time of 4.68 cN / dtex stress (hereinafter, simply referred to as an elongation at the time of 4.68 cN / dtex stress of the fiber) of 8 to 18%. When the elongation at the time of 4.68 cN / dtex stress is 18% or less, the stretch stress in the process of producing the rubber reinforced cord can be suppressed to an appropriate range, and the rubber reinforced cord having a high elastic modulus can pass through the process. It is preferable because it can be obtained well. More preferably, it is 17% or less, More preferably, it is 16% or less, Most preferably, it is 15% or less. On the other hand, it is preferable that the elongation at the time of 4.68 cN / dtex stress is 8% or more because the spinnability is improved by suppressing the generation of fuzz in the melt spinning and drawing processes. More preferably, it is 9% or more, further preferably 10% or more, and particularly preferably 11% or more.

  4. Polyamide 56 fibers having the same elongation at the time of 4.68 cN / dtex stress, and low dry yield, the relaxation of the degree of amorphous orientation during the dry heat treatment is suppressed, and 4 after the dry heat treatment. .68 cN / dtex is preferred because the elongation at the time of stress is low. Therefore, the dry yield is preferably 8% or less, more preferably 6% or less, further preferably 4% or less, and particularly preferably 1 to 3%.

  The strength of the polyamide 56 fiber is preferably 6 to 12 cN / dtex. A strength of 6 cN / dtex or more is preferable because a rubber reinforcing cord having high strength can be obtained and a rubber reinforcing cord which does not easily fatigue is obtained. More preferably, it is 7 cN / dtex or more, More preferably, it is 8 cN / dtex or more. There is no upper limit because the higher the strength, the better, but the limit is 12 cN / dtex or less.

  The polyamide 56 fiber having a degree of elongation of 10 to 40% is preferable because the rubber-reinforced cord has an appropriate stretchability, and thus the rubber-reinforced cord has a high processability in the manufacturing process. More preferably, it is 13 to 30%, and further preferably 15 to 25%.

  The polyamide 56 fiber preferably has a strength retention after dry heat treatment at 180 ° C. for 40 hours (hereinafter sometimes referred to as heat resistant strength retention) of 60% or more. When the heat-resistant and strong retention rate is 60% or more, even when exposed to heat in the vulcanization process or in an actual use environment, the rubber-reinforced cord has a low strength reduction, and a rubber-reinforced cord having excellent fatigue resistance can be obtained. Therefore, it is preferable. More preferably, it is 70% or more, More preferably, it is 80% or more. The higher the heat resistant strength retention rate, the more preferable, and 100% is most preferable.

  It is preferable that the polyamide 56 fiber contains an anti-aging agent in that the heat resistant and strong retention rate of the polyamide 56 fiber is increased. As an antioxidant, a conventionally known antioxidant or heat stabilizer can be used alone or in combination of two or more. Examples include hindered phenol compounds, hydroquinone compounds, imidazole compounds, thiazole compounds, phosphorus compounds, and their substitutes, copper halides, potassium halides, etc. It is preferable to use one type or two or more types of anti-aging agents selected from copper halides, potassium halides, phosphorus compounds, imidazole compounds, and thiazole compounds.

  Examples of the copper halide compound include first (second) copper iodide, first (second) copper chloride, and first (second) copper acetate, among which cuprous iodide is preferred. It is preferable that content of the said copper halide is 50-1000 ppm in conversion of a copper atom with respect to the polyamide 56 fiber weight. The higher the content of the copper halide compound is, the higher the heat resistant strength retention rate is, and it is preferably 75 ppm or more, and more preferably 100 ppm or more. On the other hand, when the content is 1000 ppm or less, the spinnability is improved in the melt spinning and drawing process, and generation of fluff and yarn breakage are suppressed, which is preferable, and is preferably 700 ppm or less, and more preferably 500 ppm or less.

  Examples of the potassium halide include potassium chloride and potassium iodide. Among these, potassium iodide is preferably used. The content of potassium halide is preferably 300 to 6000 ppm based on the weight of the polyamide 56 fiber. The higher the content of potassium halide is, the higher the heat resistant strength retention rate is, and it is preferable, more preferably 300 ppm or more, and still more preferably 500 ppm or more. On the other hand, when the content is 6000 ppm or less, the spinnability is improved in the melt spinning and drawing processes, and generation of fluff and yarn breakage are suppressed, which is preferable, more preferably 4000 ppm or less, and still more preferably 2000 ppm or less.

  As the phosphorus compound, phenylphosphonic acid is preferably used. The content of phenylphosphonic acid is preferably 20 to 1000 ppm in terms of phosphorus atoms with respect to the weight of the polyamide 56 fiber. It is preferable that the content is 20 ppm or more because the heat-resistant and strong retention rate is increased. On the other hand, when phenylphosphonic acid is excessively contained, spherulites that inhibit stretchability tend to be formed. More preferably, it is 30-500 ppm, More preferably, it is 40-150 ppm.

  Further, 2-mercaptobenzimidazole is preferable as the imidazole compound, and 2-mercaptobenzthiazole is preferable as the thiazole compound. When 2-mercaptobenzimidazole or 2-mercaptobenzthiazole is used, it is preferable to use both in combination with copper halide and use as a complex of both compounds, since the heat-resistant strength retention is further increased.

  It is preferable that the amino terminal group density | concentration of the polyamide 56 fiber of this invention is 20-80 eq / ton. It is preferable that the amino terminal group is 20 eq / ton or more because the adhesion between the fiber and the adhesive is increased and the rubber reinforcing cord has high rubber adhesion. More preferably, it is 25 eq / ton or more, More preferably, it is 30 eq / ton or more. On the other hand, when the amino terminal group is 80 eq / ton or less, the fatigue resistance of the rubber-reinforced cord made of polyamide 56 fiber is increased, which is preferable. More preferably, it is 75 eq / ton or less, More preferably, it is 70 eq / ton or less.

  The polyamide 56 fiber of the present invention may contain various additives as long as the effect is not impaired. For example, weathering agents (resorcinol, salicylate, benzotriazole, benzophenone, hindered amine, etc.), end-capping agents (aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, etc.), pigments (cadmium sulfide, phthalocyanine, carbon black, etc.) ), Dyes (nigrosine, aniline black, etc.), crystal nucleating agents (talc, silica, kaolin, clay, etc.), plasticizers (octyl p-oxybenzoate, N-butylbenzenesulfonamide, etc.), antistatic agents (alkyl sulfates) Type anionic antistatic agent, quaternary ammonium salt type cationic antistatic agent, nonionic antistatic agent such as polyoxyethylene sorbitan monostearate, betaine amphoteric antistatic agent, etc.), flame retardant (melamine cyanurate) , Magnesium hydroxide, aluminum hydroxide Hydroxide, ammonium polyphosphate, brominated polystyrene, brominated polyphenylene oxide, brominated polycarbonate, brominated epoxy resins or combinations of these brominated flame retardants and antimony trioxide), matting agents (oxidized) Titanium, calcium carbonate, etc.) and other polymers (other polyamides, polyesters, etc.). These can be added by appropriately selecting the addition amount, the addition step and the like in any step of producing the polyamide 56 fiber.

  Since the polyamide 56 fiber of the present invention is made of polyamide 56 which is a biomass plastic, it is excellent in environmental adaptability and has a high elastic modulus and low dry yield. Therefore, it is a fiber having a high elastic modulus even after being exposed to heat. In addition, since it has excellent rubber adhesion as described later, it is particularly suitable as a rubber reinforcing cord. And since it is also high intensity | strength, it is used suitably also as a fiber for general industrial materials other than a rubber reinforcement cord. For example, it is preferably used as a fiber constituting a vehicle interior material or a safety part of an automobile, an aircraft, etc., and examples thereof include an airbag, a seat belt, a seat, and a mat. It is also suitable for applications requiring high strength and high elastic modulus, such as fishing nets, ropes, safety belts, slings, tarpaulins, tents, braids, curing sheets, canvas, and sewing threads.

  Next, the rubber reinforcing cord of the present invention will be described. The rubber reinforcing cord of the present invention has a thin and long form including at least fibers and an adhesive, and is a cord used for the purpose of reinforcing rubber typified by a tire cord.

  In the present invention, a rubber reinforcing cord made of polyamide 56 fiber is defined as a part or all of the fibers constituting the cord being polyamide 56 fiber. The inventors of the present invention have found that when part or all of the fibers constituting the rubber reinforcing cord are polyamide 56 fibers, rubber adhesion superior to that of the conventional rubber reinforcing cord made of polyamide 66 is exhibited. By having excellent rubber adhesion, it is possible to efficiently reinforce the reinforcing rubber in which the rubber reinforcing cord is embedded. Furthermore, since the rubber-reinforced cord made of the polyamide 56 fiber of the present invention has a low elastic modulus after dry heat treatment, it is possible to obtain a reinforced rubber that hardly undergoes dimensional change by an external force. The rubber reinforced cord of the present invention is excellent in rubber adhesion and elastic modulus after dry heat treatment, and also has good strength and heat-resistant strength retention, so that fatigue resistance as a further merit This is an excellent rubber reinforcement cord.

  Fatigue resistance can be evaluated by the tube fatigue strength (minutes) described in the examples, and the longer the length, the better the rubber-reinforced cord with excellent fatigue resistance. The tube fatigue strength (minute) is preferably 1000 minutes or more, more preferably 1300 minutes or more, and further preferably 1500 minutes or more.

  The reason why the rubber reinforcing cord made of the polyamide 56 fiber is excellent in rubber adhesion is not certain, but probably because the polyamide 56 has more amide bond portions per unit volume than the conventional polyamide 66 and polyamide 6, Bonds formed between the fiber and the adhesive (for example, hydrogen bonds formed between oxygen in the —CO— group of the polyamide and hydrogen in the —OH group of the adhesive, or —NH of the polyamide The chemical bond formed by dehydration condensation between the — group and the —OH group of the adhesive is increased, and it is estimated that the adhesion is improved.

  The fibers constituting the rubber reinforcing cord of the present invention may contain other conventionally known fibers (synthetic fibers, semi-synthetic fibers, natural fibers) in addition to the polyamide 56 fibers. However, the polyamide 56 fiber content with respect to the total weight of the rubber reinforcing cord is 40 in order to make use of the excellent rubber adhesiveness of the polyamide 56 fiber and to make the rubber reinforcing cord excellent in environmental adaptability. It is preferably not less than wt%, preferably not less than 60 wt%, and more preferably not less than 80 wt%. When the rubber reinforcing cord of the present invention includes other fibers, it is preferable that the other synthetic fibers are covered with polyamide 56 fibers. For example, it is preferable to arrange other synthetic fibers in the innermost layer, arrange polyamide 56 fibers in the outer layer, and arrange an adhesive in the outermost layer, because the excellent rubber adhesiveness of the polyamide 56 fibers can be easily utilized.

The rubber reinforced cord of the present invention preferably includes a twisted polyamide 56 fiber and an adhesive (hereinafter, the twisted fiber is referred to as a raw cord and the fiber before the twist is referred to as a raw yarn). There is). More preferably, it is composed of a raw cord having a twisted structure and an adhesive. The twisted structure is a twisted structure in which two twisted yarns to which a lower twist (Z twist) is added are combined, and an upper twist (S twist) is further added. The twist coefficient (upper twist or lower twist) is preferably in the range of 1000 to 3000, respectively. A twist coefficient of 1000 or more is preferable because the fatigue resistance of the rubber-reinforced cord is increased. On the other hand, it is preferable that the twisting coefficient is 3000 or less because a decrease in strength is small from the raw yarn and the strength can be used efficiently. More preferably, it is 1300-2500.
Twist coefficient of upper twist portion = T ₁ × (D × 0.9) ^0.5
Twist coefficient of lower twist portion = T ₂ × (D / 2 × 0.9) ^0.5
T ₁ : Number of upper twists per 10 cm T ₂ : Number of lower twists per 10 cm D: Total fineness of cord (dtex)

  A conventionally well-known adhesive agent can be used for the adhesive agent which comprises the rubber reinforcement cord of this invention. What is necessary is just to select content of an adhesive agent in the range of 1-10 wt%.

  The total fineness of the rubber reinforced cord of the present invention is preferably 500 to 10,000 dtex. It is preferable that the total fineness of the rubber-reinforced cord is 500 dtex or more because the strength of the cord is increased and the change in physical properties in a high-order processing step can be suppressed. More preferably, it is 700 dtex or more, More preferably, it is 1000 dtex or more. Further, it is preferable that the total fineness of the rubber-reinforced cord is 10,000 0000 dtex or less because the adhesive area between the cord and the rubber is increased and the adhesiveness is improved. More preferably, it is 7,000 dtex or less, More preferably, it is 5,000 dtex or less.

  The rubber-reinforced cord of the present invention preferably has an elongation at the time of 2.34 cN / dtex stress of 11 to 19% after being subjected to dry heat treatment at 150 ° C. for 30 minutes (hereinafter, cord after dry heat treatment). Of 2.34 cN / dtex stress in some cases). This is an index of the elastic modulus of the cord after the dry heat treatment, and the lower the value, the higher the elastic modulus.

  If the cord is formed using the same fiber in the process of manufacturing the rubber reinforced cord, the elongation at the time of 2.34 cN / dtex stress of the cord after the dry heat treatment becomes a substantially constant value. Since the conventional polyamide 56 fiber has a low elastic modulus after dry heat treatment, a rubber-reinforced cord excellent in the reinforcing effect of the present invention and excellent in fatigue resistance could not be obtained from the fiber.

  Since the rubber reinforced cord of the present invention is made of polyamide 56 fiber having a high elastic modulus after dry heat treatment, a cord having a high elastic modulus after dry heat treatment can be formed. And, as will be described later, since the dry yield is low, the excellent adhesiveness of the polyamide 56 is utilized and the rubber adhesiveness is excellent, so that the rubber can be reinforced efficiently. And even if heat is applied, it is difficult to change the dimensions by an external force, which is preferable. For example, when used as a tire cord, even if the tire generates heat due to continuous running or high speed running, it is preferable that the size of the tire hardly increases. The elongation at the time of 2.34 cN / dtex stress of the cord after the dry heat treatment is more preferably 18% or less, and further preferably 17% or less. The lower limit is not particularly limited, but about 11% is a manufacturing limit.

  The rubber-reinforced cord of the present invention preferably has an elongation at the time of 2.34 cN / dtex stress of 5 to 15% (hereinafter sometimes referred to as the elongation of the cord at the time of 2.34 cN / dtex stress). . This is an index of the elastic modulus of the cord. It is preferable that the elongation at the time of 2.34 cN / dtex stress of the rubber reinforcing cord is 15% or less because a reinforcing rubber having a small dimensional change due to an external force can be obtained in an initial state immediately after the reinforcing rubber is produced. For example, when used for tire applications, deformation of the tire due to air pressure is suppressed, which is preferable. The lower the elongation at the time of 2.34 cN / dtex stress, the more preferable the deformation of the reinforcing rubber is suppressed, and the elongation at the time of 2.34 cN / dtex stress is more preferably 13% or less, and more preferably 11% or less. More preferably. On the other hand, by setting the elongation at the time of 2.34 cN / dtex stress to 5% or more, the calorific value (hysteresis loss) generated by repeated deformation such as elongation or compression applied to the reinforcing cord in the rubber can be reduced. Since the calorific value from the cord becomes small, a decrease in elastic modulus and strength deterioration of the cord over time can be suppressed, and a reinforced rubber excellent in fatigue resistance can be obtained, which is preferable. More preferably, it is 6% or more, More preferably, it is 7% or more. The method for measuring the elongation at the time of 2.34 cN / dtex stress of the cord will be described in detail in the Examples, and is defined as the elongation at the time of stress of 2.34 cN / dtex in the SS curve of the cord.

  The dry yield of the rubber reinforced cord of the present invention is preferably 1 to 10%. The dry yield is calculated by the following formula and is a shrinkage rate after a dry heat treatment at 150 ° C. for 30 minutes. Specific measurement methods will be described in detail in Examples. Low dry yield is preferable because stress generated by heat shrinkage is low, stress concentration on the bonding interface is suppressed, and the excellent adhesion of polyamide 56 is easily utilized. Further, the lower the dry yield, the lower the elongation at the time of the 2.34 cN / dtex stress of the cord after the dry heat treatment, which is preferable. Accordingly, the dry yield is preferably 10% or less, more preferably 8% or less, and further preferably 6% or less. The lower the yield, the more preferable, and most preferably 1 to 5%.

  The rubber-reinforced cord of the present invention is more preferable as the strength is higher because a reinforced rubber having higher fatigue resistance can be obtained. The strength is preferably 5 cN / dtex or more, more preferably 6 cN / dtex or more, and further preferably 7 cN / dtex or more. The higher the strength, the better, so there is no upper limit, but 10 cN / dtex or less is the manufacturing limit.

  The elongation of the rubber-reinforced cord of the present invention is preferably 10 to 40% because it has an appropriate stretchability, and thus the process passability in the manufacturing process of the reinforced rubber is increased. More preferably, it is 13 to 30%, and further preferably 15 to 25%.

  The rubber-reinforced cord of the present invention preferably has a strength retention of 60% or more after dry heat treatment at 180 ° C. for 40 hours (hereinafter sometimes referred to as the heat-resistant strength retention of the cord). The higher the heat resistant strength retention rate of the cord, the better the fatigue resistance. More preferably, it is 70% or more, More preferably, it is 80% or more. The higher the heat resistant strength retention rate, the better, so there is no upper limit, and 100% is the most preferable. It is preferable to use the polyamide 56 fiber having a high heat-resistant strength retention rate because the heat-resistant strength retention rate of the rubber reinforced cord is increased.

  The rubber reinforcing cord of the present invention can be used for a wide variety of reinforcing rubbers. For example, rubber reinforced cords suitable for a wide range of applications, such as tires for passenger cars, trucks, motorcycles, aircraft, etc., rubber belts and rubber hoses for automobiles and general materials, and reinforced rubber can be obtained.

  Next, the manufacturing method of the polyamide 56 fiber of this invention is demonstrated more concretely.

  According to the production method of the present invention, many oriented crystal phases can be formed in the polyamide 56 fiber, so that the amorphous chains are constrained by many crystal phases, and even when subjected to a dry heat treatment at 150 ° C. for 30 minutes, the amorphous chains are amorphous. It is difficult to cause chain orientation relaxation, resulting in a high modulus fiber.

  The production process of the polyamide 56 fiber is classified into a monomer synthesis process, a polymerization process, and a spinning process (melt spinning process, stretching process), and it is particularly important to promote oriented crystallization of the polyamide 56 fiber in the spinning process. . In the monomer synthesis process and the polymerization process, it is preferable to produce a polymer having high melt storage stability, high molecular weight, and low molecular weight distribution to promote orientation crystallization in the yarn production process, and use it in the yarn production process. .

  First, in the monomer synthesis step, 1,5-diaminopentane, which is a diamine monomer of the polyamide 56 of the present invention, is synthesized from a biomass-derived compound such as glucose or lysine by an enzyme reaction, a yeast reaction, a fermentation reaction, or the like. It is preferable. According to the above method, since the content of compounds such as 2,3,4,5-tetrahydropyridine and piperidine is small and high-purity 1,5-diaminopentane can be prepared, polyamide 56 having high melt storage stability is obtained. Therefore, the molecular weight is hardly lowered in the melt spinning process, and orientation crystallization is easily performed in the melt spinning and stretching processes. It is also preferable because of the merit of excellent environmental adaptability. Specifically, it is disclosed in JP-A-2002-223771, JP-A-2004-114, JP-A-2004-208646, JP-A-2004-290091, JP-A-2004-298034, JP-A-2002-223770, JP-A-2004-2222569, and the like. Polyamide 56 polymerized using 1,5-diaminopentane or 1,5-diaminopentane adipate prepared is preferable.

  In the polymerization process, a melt polymerization method, an interfacial polymerization method, a solution polymerization method, a solid phase polymerization method or the like can be adopted as the polymerization method. However, if the polymerization time is prolonged, the intramolecular desorption of 1,5-diaminopentane is performed. The ammonia reaction may produce basic amines such as 2,3,4,5-tetrahydropyridine, piperidine, ammonia, etc., which may reduce the melt storage stability of the polyamide 56 resin. Therefore, it is preferable to obtain the polyamide 56 having a high degree of polymerization in a shorter time, and it is preferable to use a polyamide 56 resin obtained by increasing the degree of polymerization of the polyamide 56 resin prepared in advance by the melt polymerization method by the solid phase polymerization method. For example, in the case of a melt polymerization method, methods such as JP2003-292612 and JP2004-75932 are preferably used.

  For the solid-phase polymerization method, pelletized polyamide 56 resin is resin pellets having a target degree of polymerization in a temperature range of 130 to 200 ° C. for 1 to 48 hours in a vacuum or in a nitrogen atmosphere. Solid phase polymerization is preferred until

  It is preferable to set the temperature of the solid phase polymerization to 200 ° C. or less because the degree of polymerization is easily uniformed between the inner and outer layers of the resin pellets. 195 ° C. or lower is more preferable, and 190 ° C. or lower is further preferable. On the other hand, the higher the temperature of the solid phase polymerization, the shorter the treatment time for obtaining a resin with a desired degree of polymerization, which is preferable, preferably 140 ° C. or higher, and more preferably 150 ° C. or higher. .

  Similarly, the degree of polymerization can be made uniform in the inner and outer layers of the resin pellets, and in terms of easy to obtain a polymer having a small molecular weight distribution, the longer the solid phase polymerization time, the more preferably 2 hours or more, and more preferably 3 hours. More preferably, it is the above. On the other hand, in order to increase productivity, it is preferable to shorten the solid phase polymerization, more preferably 36 hours or less, and further preferably 24 hours or less.

  From the viewpoint of easily obtaining a resin having a higher degree of polymerization and a smaller molecular weight distribution, solid phase polymerization is preferably carried out under reduced pressure, and the pressure is preferably 150 Pa or less, and more preferably 80 Pa or less. It is preferable to perform solid-state polymerization under the above conditions because a polyamide 56 resin having a low degree of dispersion is obtained, and oriented crystallization of the polyamide 56 can be promoted in the fiber manufacturing process.

  The higher the degree of polymerization of the polyamide 56 resin, that is, the higher the molecular weight, the higher the spinning stress in the melt spinning step, which is preferable because it can promote the oriented crystallization of molecular chains in the polyamide 56 fiber. Also, by controlling the molecular weight to an appropriate level, the melt fluidity of the resin can be secured and the spinning temperature can be set low, which is preferable because the thermal decomposition of the polyamide 56 resin can be suppressed. Therefore, the relative viscosity of sulfuric acid, which is an indicator of the molecular weight of the polyamide 56 resin, is preferably 3 to 6, more preferably 3.3 to 5.5, and even more preferably 3.5 to 5.0. .

  In order to adjust the amino terminal group concentration in the obtained polyamide 56 fiber to a preferable range in the present invention, the amino terminal group concentration of the polyamide 56 resin is preferably 10 to 80 eq / ton. More preferably, it is 15-75 eq / ton, More preferably, it is 20-70 eq / ton. In order to set the amino terminal group concentration within the above range, a method of adjusting the degree of polymerization within the above-described molecular weight range or a method of adding the above-described end-blocking agent at any stage of the polymerization process can be employed. .

  The polyamide 56 resin thus obtained is heat-dried, conditioned and then subjected to melt spinning. The lower the moisture content of the polyamide 56 resin used for melt spinning, the lower the molecular weight at the time of melt storage, the more preferable it is, 1000 ppm or less is preferable, 900 ppm or less is more preferable, and 800 ppm or less is more preferable. On the other hand, by including an appropriate amount of moisture, it is possible to avoid the problem of gelation during melt spinning, preferably 50 ppm or more, more preferably 80 ppm or more, and even more preferably 100 ppm or more. . The humidity control method is not particularly limited. For example, a method of allowing the polyamide 56 resin to exist in an environment in which the temperature and humidity are controlled until the moisture content reaches a desired moisture content can be employed. Here, the moisture content is a value measured at 180 ° C. using a Karl Fischer coulometric titration moisture meter.

  In the melt spinning step, the spinning temperature is preferably 260 to 310 ° C. A spinning temperature of 260 ° C. or higher is preferable because the polyamide 56 resin exhibits sufficient melt fluidity, the discharge amount between the discharge holes can be made uniform, and high-stretching can be stably performed. More preferably, it is 270 degreeC or more, More preferably, it is 275 degreeC or more. On the other hand, the temperature is preferably 310 ° C. or lower because the thermal decomposition of the polyamide 56 resin can be suppressed, the molecular weight is high, and the liquid can be discharged in a low dispersity state. More preferably, it is 300 degrees C or less, More preferably, it is 295 degrees C or less.

  If the residence time in the melt spinning process (the time until the polyamide 56 resin is melted and discharged from the spinneret) becomes longer, the molecular weight of the polyamide 56 resin may decrease and the degree of dispersion may increase. The time is preferably 30 minutes or less, more preferably 25 minutes or less, and even more preferably 20 minutes or less.

  In the melt spinning step, it is preferable that a uniaxial and / or biaxial extruder is attached to the melting portion. Since the above-mentioned extruder can guide the polymer 56 resin, polymer pump, and spinning pack while applying an appropriate pressure to the polyamide 56 resin, it does not cause abnormal stagnation in these flow paths and is excellent in spinnability.

  By being excellent in spinnability, it becomes easy to achieve a high take-up speed and a high magnification stretching as described later. In order to be excellent in spinnability, it is also preferable to filter the polyamide 56 resin with a SUS nonwoven fabric filter, sand, or the like before discharging from the spinneret.

  In order to obtain a polyamide 56 fiber having an elongation at the time of 4.68 cN / dtex stress of 20% or less after the dry heat treatment of the present invention, in the melt spinning and drawing process, the moisture absorption of the polyamide 56 fiber is suppressed to the limit. It is obtained by uniformly orienting the molecular chain and promoting oriented crystallization.

  Therefore, after the polyamide 56 fiber discharged from the die is cooled and solidified with cooling air, a non-hydrous oil agent is attached, and after drawing, heat treatment and relaxing treatment with a dry heat source, winding is performed, a direct spinning drawing method It is particularly important to adopt The draw rate is 0.4 to 4 km / min, the draw ratio applied at a draw temperature of 100 to 245 ° C. is 1.3 times or more, the maximum heat treatment temperature is 210 to 250 ° C., and the relax ratio is 0.85 to 0.00. It is important to set it to 95. The requirements for these production methods are described in detail below.

  First, it is preferable to cool and solidify with cooling air because it is easy to form an orientation in the stretching process by suppressing the moisture absorption of the fiber discharged from the die. The temperature of the cooling air is preferably 0 to 25 ° C. and the relative humidity is preferably 20 to 70%. Similarly, the indoor temperature / humidity environment for melt spinning and stretching should be adjusted to a temperature of 20-30 ° C, a relative humidity of 40-65%, a temperature within ± 5 ° C, and a humidity within ± 5%. Is preferred. Although the cooling efficiency is high by means such as water cooling of the discharged fibers, the fibers of the present invention tend to absorb excessive moisture before stretching, and orientation formation in the stretching process tends to be hindered. It is not adopted as a cooling method for 56 fibers.

  Further, if the rubbing with a roll or a guide is large, it tends to cause a decrease in strength of the obtained fiber and generation of fluff. Therefore, it is preferable to attach a spinning oil agent at a stage before taking up the fiber. It is important that the oil agent is a non-water-containing oil agent that does not contain water from the viewpoint of suppressing the moisture absorption of the fiber. The non-water-containing spinning oil may be any one obtained by diluting oil agent active ingredients such as a smoothing agent, an antistatic agent, and an emulsifier with a mineral oil having 12 to 20 carbon atoms, and conventionally known ones can be used. .

  Similarly, since it is important to suppress moisture absorption of the fiber in the stretching step, it is preferable to employ a dry heat source such as a heating roll, a hot plate, a dry heat furnace, or a laser as a heat source for stretching or heat treatment. . Since it is more excellent in heating efficiency, it is preferable to use a heating roll as a heat source. In a wet heat source such as warm water or steam, the polyamide 56 fibers absorb moisture in the stretching process, and the intermolecular interaction is weakened, and it tends to be difficult to orient uniformly.

  In order to suppress the moisture absorption of the fiber and orient the molecular chain, it is preferable to employ a direct spinning drawing method. In the direct spinning drawing method, the fiber discharged from the die is taken up by a roll and then drawn continuously at a speed ratio with the roll arranged thereafter, and melt spinning and drawing are performed in one step. It is a manufacturing method. By drawing the fiber without winding it once, it can be used for drawing in a state where moisture absorption of the fiber is suppressed, and therefore, orientation crystallization can be promoted in the drawing step, which is preferable. In the two-step method in which melt spinning and drawing are performed in separate steps, the polyamide 56 fibers tend not to be oriented and crystallized in the drawing step due to moisture absorption in the undrawn yarn package state.

  The take-up speed is preferably 0.4 to 4 km / min. By setting the take-up speed to 0.4 km / min or more, it is possible to shorten the elapsed time until the fiber discharged from the die is taken and used for drawing, and moisture absorption of undrawn yarn is suppressed. In the subsequent stretching step, the amorphous chain is easily oriented, which is preferable. Furthermore, due to the effect of increasing the spinning stress, a large number of microcrystals are formed in the undrawn yarn, and the presence of the microcrystals moderately increases the interaction between the molecular chains, making it easy to orient the amorphous chains uniformly in the drawing process. Therefore, it is preferable. When the heat setting is performed, the crystallites become nuclei and orientation crystallization is promoted, which is preferable. Therefore, the take-up speed is more preferably 0.7 km / min or more, and further preferably 0.9 km / min or more.

  On the other hand, it is preferable that the take-up speed is 4 km / min or less and the spinning stress is suppressed to an appropriate range, so that the crystal size formed in the undrawn yarn is reduced and the stretchability is increased, resulting in a high-strength fiber. . In addition, the spun yarn breakage is less likely to occur, which is preferable. In order to obtain high-strength fibers with good passability in the production process, it is preferable to keep the take-up speed within an appropriate range, and the take-up speed is more preferably 3.6 km / min or less, and 2.6 km / min or less. Further preferred.

  The conventional polyamide 66 tends to decrease in strength and increase in fluff when the take-up speed is increased. Presumably, the polyamide 66 has high crystallinity, and when the take-up speed is increased, the crystal becomes coarse in the undrawn yarn to become spherulites, and stretching stress concentrates on the spherulites, resulting in frequent occurrence of fluff and lowering of stretchability. This is presumed to be the cause. On the other hand, the polyamide 56 fiber is derived from its low crystallinity, and even if it is a high-speed take-up yarn, the crystals formed in the fiber are fine and difficult to form spherulites. Then, there is a merit that it is easy to obtain high-quality fibers with less fuzz even when the take-up speed is high.

The undrawn yarn taken up may be drawn at an overall draw ratio at which the obtained polyamide 56 fiber has an elongation at the time of 4.68 cN / dtex stress of 8 to 18%, but at this time, it is drawn in two or more stages. This is preferable because the amorphous chain can be easily highly oriented and oriented crystallization can be promoted. More preferably, it is 3 steps or more, more preferably 4 steps or more, and particularly preferably 5 steps or more. Here, the total draw ratio is defined by the following formula.
Total draw ratio = final roll speed / first roll speed (= take-off speed).

  Since the overall draw ratio is determined by the amorphous orientation degree and the crystallinity degree of the undrawn yarn, the draw ratio tends to be lower as the take-up speed is higher. For example, when the take-up speed is 0.4 km / min or more and less than 1 km / min, the draw ratio is preferably 3 to 6 times, and when the take-up speed is 1 km / min or more and less than 2 km / min, 1.5-4. If the take-up speed is 2 km / min or more and less than 3 km / min, it is preferably 1.4 to 3 times, and if the take-up speed is 3 km / min or more and 4 km / min or less, 1 It is preferably 3 to 2.5 times.

  And in order to make the amorphous chains of the highly hygroscopic polyamide 56 fibers uniformly oriented in the stretching process, it is important that the stretching ratio applied at a stretching temperature of 100 to 245 ° C. is 1.3 times or more. is there. In the case of performing multi-stage stretching, this means that the stretching ratio applied in a low temperature range of less than 100 ° C. is set low, and the stretching ratio applied in a high temperature range of 100 ° C. or higher is increased. And when the take-up speed is high, the yarn swaying on the roll is suppressed by the effect of forming microcrystals in the undrawn yarn, and therefore the drawing temperature can be set to 100 ° C. or higher from the first roll. preferable. By stretching the fiber after heating it to a temperature of 100 ° C or higher, it will be stretched after the fiber has been heated above the boiling point of water. In addition, since the intermolecular interaction is increased, the stretching stress is uniformly transmitted to the amorphous chain, and the uniformity of the orientation is increased. On the other hand, when the stretching temperature is 245 ° C. or lower, the mobility of the amorphous chain is suppressed to an appropriate range, and the amorphous chain is highly oriented without causing orientation relaxation. A more preferable range of the stretching temperature is 120 to 235 ° C, and a more preferable range is 140 to 225 ° C. In the conventional polyamide 66 fiber, a high-strength and high-quality fiber can be obtained with good processability, so that the draw ratio in a high temperature range of 100 ° C. or higher is set rather low, and a low temperature range of less than 100 ° C. Therefore, the stretching tends to be preferably performed at as high a magnification as possible. This is presumably because spherulites were easily formed on a heated roll having a stretching temperature of 100 ° C. or higher before being subjected to stretching, due to the high crystallinity of polyamide 66. On the other hand, the polyamide 56 fiber is derived from its low crystallinity, and spherulites are hardly formed even on a heated roll having a stretching temperature of 100 ° C. or higher. Therefore, in order to eliminate the adverse effects due to high hygroscopicity, it is preferable to set the draw ratio applied in a low temperature region below 100 ° C. low and increase the draw magnification applied in a high temperature region above 100 ° C. The stretching ratio at a stretching temperature of 100 to 245 ° C. is preferably as high as possible, and the stretching ratio applied at the above stretching temperature is more preferably 1.5 times or more, and further preferably 1.7 times or more. . And what is necessary is just to determine in the range used as the comprehensive draw ratio from which the elongation at the time of 4.68 cN / dtex stress of the fiber obtained will be 8 to 18%.

  Here, the stretching temperature is defined as follows. For example, when stretching is performed between two heating rolls using a heating roll as a heat source, the stretching temperature is defined as the temperature of the upstream roll. When stretching is performed by placing a hot plate between rolls, the stretching temperature is defined as the temperature of the hot plate. When extending | stretching by arrange | positioning a heating furnace between rolls, extending | stretching temperature is defined as the temperature of a heating furnace. Moreover, when extending | stretching using heat sources, such as a carbon dioxide laser, the yarn temperature measured with thermometers, such as an infrared radiation thermometer, is made into extending | stretching temperature.

For example, a method for calculating a stretching ratio at a stretching temperature of 100 to 245 ° C. when a non-heated roll and a heated roll are used in combination and multistage stretching is performed between a plurality of rolls is exemplified below. It is a case where five-stage stretching is performed by winding from the first roll through the sixth roll, and the first roll temperature is 25 ° C, the second roll temperature is 60 ° C, the third roll temperature is 145 ° C, the fourth roll is 210 ° C, The fifth roll is 230 ° C. and the sixth roll is 25 ° C., and the film is stretched at a stretch ratio r ₁ according to the speed ratio between the first roll and the second roll, and at the stretch ratio r ₂ according to the speed ratio between the second roll and the third roll. stretched, by the speed ratio between the third roll and the fourth roll stretching at a draw ratio r _3, the speed ratio between the fourth roll and fifth roll was stretched at a draw ratio r _4, 5 roll and the sixth roll when relaxation treatment in a relaxed magnification r ₅ by the speed ratio between, and the stretching ratio in a stretching temperature one hundred to two hundred and forty-five ° C. is obtained as an integrated value of the draw ratio to be applied between the fifth roll from the third roll. And it shall from the fifth roll not recorded sixth ones of less than 1, such as a relaxation factor r ₅ which is applied by the relaxation treatment between the rolls. That is, in the above-described case, the draw ratio at a draw temperature of 100 to 245 ° C. is r ₃ × r ₄ .

  And in the range of 245 ° C. or lower, by stretching the stretching temperature stepwise, it is possible to stretch while enhancing the intermolecular interaction by partially crystallizing the oriented amorphous chain, It is preferable because the stretching stress is easily transmitted to the molecular chain.

  It is important that the maximum heat treatment temperature is 210 to 250 ° C. The maximum heat treatment temperature is the temperature of the heat treatment performed at the highest temperature in the heat treatment performed in the stage before winding the drawn yarn. For example, in the case of the method of performing stretching with the first to sixth rolls, the temperature of the heat treatment performed with the fifth roll corresponds to the maximum heat treatment temperature. Moreover, since it is preferable to raise extending | stretching temperature in steps, it is preferable to perform the heat processing performed at the highest heat processing temperature with a final heating roll. The polyamide 56 molecules highly oriented by the above-described melt spinning and stretching methods are heat-set at a temperature of 210 ° C. or higher, so that the oriented amorphous crystallizes, and the restraint property of the amorphous chain is enhanced by the crystal. On the other hand, if the temperature of the maximum heat treatment temperature is higher than 250 ° C., the yarn is fused to the roll and breakage of the yarn may occur, which may deteriorate the process passability. Further, although crystallization is promoted, the orientation state of the amorphous chain cannot be maintained, and the strength may be lowered. Therefore, the temperature of the maximum heat treatment temperature is more preferably 215 to 245 ° C, and further preferably 220 to 240 ° C.

  After the stretching, it is preferable to perform a relaxation treatment depending on the speed ratio between the final heating roll and the final roll. The relaxation treatment refers to a case where the relaxation magnification defined by the final roll speed / final heating roll speed is less than 1, and the relaxation magnification is preferably 0.85 to 0.95. Since the relaxation magnification is 0.95 times or less, non-uniform distortion applied to the amorphous chain in the stretching process is averaged, and the amorphous chain is stabilized. . More preferably, it is 0.94 times or less, More preferably, it is 0.93 times or less. The lower the relaxation ratio, the better. However, when the relaxation ratio is 0.85 or more, strain is averaged without causing relaxation of the orientation of the amorphous chain, which is preferable because the fiber becomes high in strength. And since moderate thread | yarn tension expresses between rolls and process passability becomes favorable, it is preferable. More preferably, it is 0.86 or more, More preferably, it is 0.87 or more.

  The polyamide 56 fiber is wound with a winding tension of 0.05 to 0.15 cN / dtex or less. A winding tension of 0.15 cN / dtex or less is preferable because the problem of package tightening can be avoided, and a winding tension of 0.05 cN / dtex or more improves the package foam. More preferably, it is 0.07-0.13 cN / dtex, More preferably, it is 0.09-0.11 cN / dtex.

  The polyamide 56 fiber produced by the above method has many oriented crystal phases in the fiber, so the amorphous chain is highly constrained, and even when subjected to dry heat treatment at 150 ° C. for 30 minutes, the orientation of the amorphous chain is relaxed. This is preferable because high elasticity is maintained.

  By preparing two twisted yarns obtained by adding the lower twist (Z twist) to the polyamide 56 fiber (raw yarn) obtained in this way, and adding them to the upper twist (S twist), raw cord And What is necessary is just to select the number of lower twists and the number of upper twists so that it may become the range mentioned above, respectively. And after apply | coating an adhesive agent to a raw | natural cord, the rubber reinforcement cord of this invention is obtained by winding after carrying out constant length heat processing, stretch heat processing, and relaxation heat processing.

  A conventionally well-known adhesive agent can be used for an adhesive agent. The concentration of the adhesive is preferably 5 to 30 wt%, more preferably 7 to 25 wt% from the viewpoint of the fluidity of the adhesive and the uniform adhesion to the cord.

  In order to ensure the running stability of the cord in the adhesive bath, it is preferable to stretch by the speed ratio of the rolls before and after the adhesive bath. The stretch rate before and after the adhesive bath may be adjusted within a range of 1 to 10%.

  The amount of adhesive can be selected according to the intended application, but the higher the amount of adhesive, the better the adhesion, but by keeping the amount of adhesive moderate, the flexibility of the cord is ensured and fatigue resistance is also good It becomes. Therefore, the adhesion amount is preferably 1 to 10 wt%, more preferably 2 to 8 wt%, and further preferably 3 to 7 wt%. Here, the adhesion amount of the adhesive is obtained by dividing the weight of the adhesive adhered to the cord by the total weight of the cord and multiplying it by 100.

  As a heat source for performing constant length heat treatment, stretch heat treatment, and relaxation heat treatment, it is preferable to use a non-contact type dry heat furnace from the viewpoint of uniformly covering the fiber surface with the adhesive.

  After applying the adhesive, it is preferable to perform constant-length heat treatment for 1 to 180 seconds in a drying furnace having an atmospheric temperature of 100 to 150 ° C. It is preferable to remove moisture in advance by constant-length heat treatment because orientation crystallization is further promoted by stretch heat treatment.

  The dried cord is subjected to a stretch heat treatment in a heat treatment furnace having an atmospheric temperature of 200 to 250 ° C. for a treatment time of 1 to 180 seconds, whereby the adhesive and the cord react and adhere. At this time, the cord tension at the outlet of the heat treatment furnace is adjusted by the range in which the stretch stress is 0.5 to 2.5 cN / dtex, which is a value obtained by dividing the cord tension by the fineness of the rubber reinforced cord. The elongation at the time of dtex stress may be adjusted to a desired value. However, the higher the stress, the higher the degree of crystal orientation that has been formed in the fiber, and the higher the 2.34 cN even after the dry heat treatment. It is preferable because a cord having a low elongation at the time of / dtex stress can be obtained. More preferably, it is 1 cN / dtex or more. On the other hand, it is preferable that the stretch stress is 2.5 cN / dtex or less because process passability in the rubber-reinforced cord manufacturing process is enhanced. More preferably, it is 2 cN / dtex or less. And in order to make a stretch stress into the said range, it is preferable to comprise a rubber reinforcement cord from the polyamide 56 fiber whose elongation at the time of 4.68 cN / dtex stress is 8 to 18%.

  Finally, relaxing heat treatment is preferably performed for 1 to 180 seconds in a heat treatment furnace having an atmospheric temperature of 200 to 250 ° C. By the heat treatment, the adhesive and the cord react and adhere. This is preferable because the strain applied to the amorphous chain by the relaxation heat treatment becomes uniform and the dry yield of the fiber is lowered. At this time, the relaxation stress, which is a value obtained by dividing the cord tension at the outlet of the heat treatment furnace by the fineness of the rubber reinforcing cord, may be adjusted in the range of 0.1 to 1 cN / dtex.

  The rubber reinforced cord thus obtained has a small dimensional change in dry heat treatment, that is, a decrease in the degree of amorphous orientation of the fiber, and thus a rubber reinforced cord having a high elastic modulus can be obtained even after being exposed to heat. And since it is excellent in rubber adhesiveness, the reinforced rubber comprised with this rubber reinforcement cord has a small dimensional change by external force, and is excellent also in durability in repeated deformation. For this reason, it can be used for a wide variety of reinforcing rubbers. The manufacturing method of the reinforcing rubber is not particularly limited, and a conventionally known manufacturing method may be adopted.

  Hereinafter, the present invention will be described in detail with reference to examples. In addition, the measuring method in an Example used the following method.

A. Relative viscosity (ηr)
A 2.5 g sample was dissolved in 25 cc of 98% sulfuric acid and measured at 25 ° C. using an Ostwald viscometer.

B. Amino end group concentration 1 g of a sample was dissolved in 50 mL of a phenol / ethanol mixed solution (phenol / ethanol = 80/20), and neutralization titration was performed with an N / 50 aqueous hydrochloric acid solution using Zimo blue as an indicator. And the amino terminal group concentration was measured from hydrochloric acid consumption.

C. The total fineness and single fiber fineness are rotated 10 times with a measuring machine of 1 m / circumference, and 5 loop-like skeins of 10 turns are prepared and used as a sample for weight measurement. Similarly, a 10-turn loop skein is prepared, and five loop skeins are formed so that the ends of the skeins are not untied and used as a sample for sample length measurement. First, a total of 10 samples were allowed to stand for 48 hours in an environment of 25 ° C. and RH 55% under no load to adjust the humidity. Thereafter, under the same environment, the weight of the loop-shaped skein for weight measurement was measured to obtain an average value A (g). Next, the skein length of the loop-shaped skein for measuring the sample length was measured in the same environment. A loop skein for measuring the sample length was applied to the hook, and a load equivalent to 0.05 cN / dtex was applied to the loop skein to measure the skein length. When determining the load, the apparent fineness of the sample (= A (g) × 10000/10) was used. The sample length was 20 times the skein length, and an average value B (m) of five sample lengths was determined. Then, after dividing A by B, the total fineness was determined by multiplying by 10,000. The single fiber fineness was determined by dividing the total fineness by the number of filaments.

D. Strength, Elongation JIS L1017 (1995), Tensile strength and elongation of 7.5, (1) Tensilon UCT-100 manufactured by Orientec Co., Ltd. was used according to the standard time test measurement method. The SS curve of the sample (fiber or rubber reinforced cord) was measured. First, a sample was removed from the package, and humidity was adjusted by leaving it to stand for 48 hours in an environment of 25 ° C. and RH 55% with no load. Then, in the same environment, the SS curve was measured with a sample length of 250 mm and a tensile speed of 300 m / min. The strength was determined by dividing the strength at the point showing the maximum strength in the SS curve by the total fineness. The elongation was obtained by dividing the elongation at the point showing the maximum strength in the SS curve by the sample length and multiplying by 100. The measurement was performed 10 times and the average value was taken.

E. Elongation at the time of 4.68 cN / dtex stress of fiber JIS L1017 (1995), elongation at constant load of 7.7, (1) Measured by the method described in D in accordance with the measurement method of the standard time test The elongation at the time of 4.68 cN / dtex stress was calculated from the SS curve of the obtained fiber. The measurement was performed 10 times and the average value was taken.

F. Elongation of cord at 2.34 cN / dtex stress JIS L1017 (1995), elongation at constant load of 7.7, (1) Measured by the method described in D, according to the measurement method of the standard time test The elongation at the time of 2.34 cN / dtex stress was calculated from the SS curve of the obtained cord. The measurement was performed 10 times and the average value was taken.

G. Elongation at 4.68 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes (fiber)
The fiber was scraped and subjected to a dry heat treatment using a gear oven GPHH-200 manufactured by Tabai Espec Co., Ltd. in a load-free state at an atmospheric temperature of 150 ° C. for a treatment time of 30 minutes. Then, the loop-shaped casserole after the dry heat treatment was taken out from the oven, and the elongation of the sample at the time of 4.68 cN / dtex stress was determined according to the method described in the section E. At this time, the same value as the fiber before the dry heat treatment was used as the total fineness of the fiber after the dry heat treatment.

H. Elongation at 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes (code)
The rubber reinforced cord was scraped, and a dry heat treatment was performed using a gear oven GPHH-200 manufactured by Tabai Espec Co., Ltd. in a load-free state at an atmospheric temperature of 150 ° C. for a treatment time of 30 minutes. Then, the loop-shaped casserole after the dry heat treatment was taken out from the oven, and the elongation at the time of 2.34 cN / dtex stress of the cord after the dry heat treatment was determined according to the method described in the section F. At this time, the total fineness of the cord after the dry heat treatment was the same value as the cord before the dry heat treatment.

I. Dry Yield JIS L1017 (1995), Dry heat shrinkage rate in Section 7.10, (2) Dry heat shrinkage of sample (fiber or rubber reinforced cord) is measured according to dry heat shrinkage rate after heating (Method B) did. First, the skeins were rotated 10 times with a 1 m / round measuring machine, and the ends of the skeins were tied together to create a looped skein that was not unraveled. The looped skein was allowed to stand for 48 hours in an environment of 25 ° C. and RH 55% under no load to adjust the humidity. Then under the same environment, over a looped hank for sample length measured in the hook, measured skein length with a load of 0.05 cN / dtex looped hank was the original length L _0.

Then, the load was removed, and the loop-shaped casserole was put into a gear oven GPHH-200 manufactured by Tabai Espec Co., Ltd., and subjected to a dry heat treatment at an atmospheric temperature of 150 ° C. and a treatment time of 30 minutes in a load-free state. The loop-shaped skein after the dry heat treatment was taken out of the oven, and again was conditioned for 48 hours in an environment of 25 ° C. and RH 55% under no load. Then, over a looped hank after dry heat treatment on the hook in the same environment, the hank length was measured under a load of 0.05 cN / dtex, it was treated after length L _1. Using L ₀ and L ₁ , dry yield was determined by the following formula. The measurement was performed 5 times, and the average value was obtained.
Dry yield = (L ₀ −L ₁ ) / L ₀ × 100

J. et al. Heat-resistant and strong retention rate A sample was scraped and subjected to a dry heat treatment using a gear oven GPHH-200 manufactured by Tabai Espec Co., Ltd. in a load-free state at an atmospheric temperature of 180 ° C. and a treatment time of 40 hours. Then, the loop-shaped casserole after the dry heat treatment was taken out of the oven and used as a sample, and the strength after the dry heat treatment was determined according to the method described in the section D. The heat-resistant strength retention was determined by dividing the strength after dry heat treatment at 180 ° C. for 40 hours by the strength of the unheat-treated sample and multiplying by 100.

K. Rubber adhesion (adhesive strength)
According to JIS 1017 (1995) Reference 1, 3.1 T test (Method A), the adhesive strength of the rubber reinforced cord was measured. First, a rubber reinforcing cord containing an adhesive was pulled out from the package, and was previously conditioned for 48 hours in a temperature and humidity environment of 25 ° C. and RH 55% under no load. The rubber reinforced cord is embedded in the rubber for evaluation, vulcanized at a vulcanization temperature of 150 ° C., a vulcanization time of 30 minutes, and a press pressure of 50 kg / cm ² while applying a tension of 0.08 cN / dtex to the cord. A test piece was prepared. At this time, the rubber embedding length was 10 mm, and the width of the embedding test piece was 10 mm. Then, a clamp with a slit width of 1.5 mm is attached to the embedded test piece, and a speed of 100 mm / min is used in an environment of 25 ° C. and humidity RH 55% by using TENSILON UCT-100 manufactured by Orientec Co., Ltd. The maximum load when the cord was pulled out from the embedded test piece was measured. The measurement was performed 10 times and the average value was obtained. The rubber for evaluation includes 80 parts by weight of natural rubber, 20 parts by weight of styrene-butadiene copolymer rubber, 40 parts by weight of carbon black, 2 parts by weight of stearic acid, 10 parts by weight of a petroleum softener, baintle, zinc white, and N-phenyl. A rubber comprising 1.5 parts by weight of β-naphthylamine, 0.75 parts by weight of 2-benzothiazyl disulfide, 0.75 parts by weight of diphenylguanidine, and 2.5 parts by weight of sulfur was used.

L. Fatigue resistance (Tube fatigue strength, GY method)
The fatigue resistance of the rubber reinforced cord was evaluated according to the tube fatigue strength (GY method) described in JIS 1017 (1995) Reference 1, 2.2.1. Using the rubber for evaluation described in item K, the tube burst pressure (minutes) was obtained at a tube internal pressure of 3.4 MPa, a rotation speed of 850 rpm (however, the rotation direction was changed every 30 minutes), and a tube angle of 90 °. did.

M.M. Tire size S ₁ after standing in the dimensions of the tire after air filling increase tire pressure 7.25 kg / cm ² at room temperature for 24 hours, and a tire size S ₀ in the mold is measured, the dimensions increase ratio after the air filling (%) Was calculated. S ₁ was obtained by measuring the maximum height H ₁ of the tire and the maximum width W ₁ of the tire after the above-described treatment, and calculating S ₁ = 2H ₁ + W ₁ . In addition, the tire dimension S ₀ in the mold was similarly measured by measuring the maximum height H ₀ and the maximum width W ₀ in the mold, and S ₀ = 2H ₀ + W ₀ . And the dimensional increase rate after air filling was calculated | required by the following formula.
Dimensional increase rate after air filling of tire (%) = (S ₁ −S ₀ ) / S ₀ × 100

N. Dimensional increase rate of tire after running on a drum The tire was pressed on a 1702 mm drum with a tire internal pressure of 7.25 kg / cm ² and a load of 2700 kg, and the tire size S ₂ after running for 24 hours at a speed of 40 km / hour was measured. ratio of increase from the size S ₁ of the tire after filling. S ₂ measures the maximum height _{H 2} and a maximum width _{W 2} of the tires after the running processing _was determined by _{S 2 = 2H 2 + W 2} .

The dimensional increase rate (%) after running the drum was obtained by the following formula.
Dimensional increase rate after drum running of tire (%) = (S ₂ −S ₁ ) / S ₁ × 100

O. Evaluation of spinning performance In obtaining 100 kg of polyamide 56 fiber, the spinning performance was evaluated based on the number of times yarn breakage occurred.

P. Moisture content Karl Fischer coulometric titration moisture meter (Hiranuma Sangyo Co., Ltd. trace moisture measuring device AQ-2000 and company's moisture vaporizer EV-200), measured by flowing dry nitrogen gas at a moisture vaporization temperature of 180 ° C did.

Q. Twist coefficient First, the number of upper twists and the number of lower twists were measured using a test twist machine manufactured by Furuhashi Seisakusho. First, the cord was set on a testing machine, and an initial load (total fineness of the cord × 0.45 mN) was applied. Next, the number of twists in the upper twisted portion was measured, and the number of twists A (turns) between 25 cm and the length B (cm) in which the twists were reduced were read. Next, one of the two cords was cut, and the number of twists C (turns) of the lower twisted portion was similarly read. Using A, B, and C, the number of upper twists and the number of lower twists were calculated according to the following calculation formula.
Upper twist number (t / 10cm) = A / 25 × 10
Lower twist number (t / 10 cm) = C / (25 + B) × 10

Using the upper twist number or the lower twist number, the twist coefficient of the upper twist part or the lower twist part was calculated by the following formula.
Twist coefficient of upper twist portion = T ₁ × (D × 0.9) ^0.5
Twist coefficient of lower twist portion = T ₂ × (D / 2 × 0.9) ^0.5
T ₁ : Number of upper twists per 10 cm T ₂ : Number of lower twists per 10 cm D: Total fineness of cord (dtex)

[Production Example 1] (Preparation of lysine decarboxylase)
E. First. E. coli strain JM109 was cultured as follows. First, this platinum strain was inoculated into 5 ml of LB medium, and precultured by shaking at 30 ° C. for 24 hours. Next, 50 ml of LB medium was placed in a 500 ml Erlenmeyer flask and preliminarily steam sterilized at 115 ° C. for 10 minutes. The strain was precultured in this medium, and cultured for 24 hours under the condition of 30 cm in amplitude and 180 rpm while adjusting the pH to 6.0 with 1N aqueous hydrochloric acid. The bacterial cells thus obtained were collected and a cell-free extract was prepared by ultrasonic disruption and centrifugation. Measurement of these lysine decarboxylase activities was carried out according to a standard method (Kenji Yokota, Haruo Misono, Biochemistry Experiment Course, vol.11, P.179-191 (1976)).

  When lysine is used as a substrate, conversion by lysine monooxygenase, lysine oxidase, and lysine mutase, which are considered to be the main main pathways, can occur. The cell-free extract of E. coli strain JM109 was heated. Furthermore, this cell-free extract was fractionated with 40% saturated and 55% saturated ammonium sulfate. Using this crude purified lysine decarboxylase solution, 1,5-diaminopentane was produced from lysine.

[Production Example 2] (Production of 1,5-diaminopentane)
An aqueous solution prepared to be 50 mM lysine hydrochloride (manufactured by Wako Pure Chemical Industries), 0.1 mM pyridoxal phosphate (manufactured by Wako Pure Chemical Industries), 40 mg / L-crudely purified lysine decarboxylase (prepared in Reference Example 1) While maintaining the pH at 5.5 to 6.5 with a 0.1N hydrochloric acid aqueous solution, the mixture was reacted at 45 ° C. for 48 hours to obtain 1,5-diaminopentane hydrochloride. By adding sodium hydroxide to this aqueous solution, 1,5-diaminopentane hydrochloride is converted to 1,5-diaminopentane, extracted with chloroform, and distilled under reduced pressure (1.33 kPa, 60 ° C.). 1,5-Diaminopentane was obtained.

[Production Example 3] (Preparation of 1,5-diaminopentane and adipic acid salt)
An aqueous solution obtained by dissolving 10.3 g of 1,5-diaminopentane produced in Production Example 2 in 25 g of water is immersed in a 40 ° C. water bath and stirred, and about 1 g of adipic acid (manufactured by Kirk) is stirred. About 0.2 g was added in the vicinity of the neutralization point, and the change in pH of the aqueous solution relative to the amount of adipic acid added was examined. The neutralization point was determined to be pH 8.66. The amount of adipic acid added at the neutralization point was 14.7 g. A 50 wt% aqueous solution of an equimolar salt of 1,5-diaminopentane and adipic acid was prepared so that the pH was 8.66.

[Production Example 4] (Polymerization of polyamide 56 resin)
Using a heating medium heating type polymerization kettle, a 50 wt% aqueous solution of equimolar salt of 1,5-diaminopentane and adipic acid, and phenylphosphonic acid are charged to 70 ppm in terms of phosphorus atom with respect to polyamide 56 resin. The heating medium temperature is set to 200 ° C. while nitrogen is purged, heating is started, the pressure in the can is controlled to 0.2 MPa, and the temperature in the can reaches 160 ° C., such as 1,5-diaminopentane and adipic acid The molar salt was concentrated. Thereafter, the polymerization kettle is sealed, the heating medium temperature is increased to 290 ° C. and the pressure is increased, and when the internal pressure of the can reaches 1.7 MPa, the internal pressure of the can is controlled at 1.7 MPa, and the internal temperature is 245 ° C. Maintained until. And after changing the heating medium temperature to 285 ° C. and releasing the pressure to atmospheric pressure over 50 minutes, the pressure inside the can is reduced to 0.088 MPa and kept for 20 minutes, then the heating is stopped and the polymer is discharged. Then, it was cooled with water to obtain a polyamide 56 resin. The polyamide 56 resin had a ηr of 2.85 and an amino end group concentration of 50 eq / ton.

[Production Example 5] (Solid phase polymerization of polyamide 56 resin)
The polyamide 56 resin obtained in Production Example 4 was charged into a vacuum dryer type vacuum dryer, a copper acetate 5 wt% aqueous solution was added as copper atoms to 150 ppm with respect to the polyamide 56 resin, and the dryer was rotated to obtain about 1 Blended for hours. And 50 wt% potassium iodide aqueous solution was added as a potassium atom so that it might become 900 ppm with respect to polyamide 56 resin, the drier was rotated again, and it blended for about 1 hour. Thereafter, by rotating the dryer, the resin in the can was reduced in pressure while stirring and heated to carry out solid phase polymerization. The pressure was reduced while heating at a temperature rise rate of 10 ° C./hour in the can, and after reaching 170 ° C., the pressure was maintained at 0.1 kPa for 3 hours in the can and then extracted. Ηr of the obtained polyamide 56 resin was 4.0, and the amino end group concentration was 32 eq / ton.

[Production Example 6] (Solid-state polymerization of polyamide 56 resin)
In Production Example 5, a copper acetate 5 wt% aqueous solution was added as copper atoms to 15 ppm with respect to the polyamide 56 resin, and a potassium iodide 50 wt% aqueous solution was added as potassium atoms to 90 ppm with respect to the polyamide 56 resin. Except that, polyamide 56 resin was obtained in the same manner as in Production Example 5. ηr was 4.0, and the amino end group concentration was 32 eq / ton.

[Production Example 7] (Production of polyamide 66 resin)
The internal pressure of the can was reduced to 0.088 MPa using a 50 wt% aqueous solution of an equimolar salt of 1,6-diaminohexane and adipic acid instead of a 50 wt% aqueous solution of an equimolar salt of 1,5-diaminopentane and adipic acid. A polyamide 66 resin of ηr 2.85 was obtained in the same manner as in Production Example 4 except that the subsequent holding time was 5 minutes. The obtained polyamide 66 resin was subjected to solid phase polymerization in the same manner as in Production Example 5 to obtain a polyamide 66 resin having ηr3.8.

[Production Example 8] (Production of RFL)
First, in the presence of an alkali catalyst, resorcin (manufactured by Kanto Chemical Co., Ltd., product name resorcin) / formalin (manufactured by Sigma Aldrich, product name: 35% formaldehyde aqueous solution) is mixed at a solid content weight ratio of 10/18 and aged for 6 hours. As a result, an initial condensate having a solid content concentration of 6.5% was obtained.

  Next, vinylpyridine-styrene-butadiene copolymer latex (manufactured by Japan A & L: PYRATEX-HM) and styrene-butadiene copolymer latex (manufactured by Japan A & L: J9049) are mixed at a solid content ratio of 70/30. 10 parts of 28% ammonia water (product name: 28% ammonia water manufactured by Sigma-Aldrich) was mixed with 100 parts of the latex thus obtained to obtain a mixed latex.

  Then, 18 parts of the condensate was mixed with 100 parts of the mixed latex and aged for 24 hours to adjust a high concentration RFL having a solid content of 20%. This high concentration RFL was diluted in water to obtain RFL with a solid content concentration of 10%.

(Example 1)
Using a direct spinning / drawing apparatus equipped with a single-screw kneader shown in FIG. 2, melt spinning, drawing, and heat treatment were successively performed to obtain polyamide 56 fibers.

  First, the polyamide 56 resin obtained in Production Example 5 was conditioned to a moisture content of 500 ppm and charged into the hopper 1 shown in FIG. Then, when melted by the single-screw extruder 2 and led to the spinning pack 6 through the polymer pipe 3, the polymer is measured and discharged by the gear pump 4, and led to the spinning pack 6 built in the spin block 5, and the round hole is formed. Spinning from a spinneret 7 having 200 holes. At this time, the rotation speed of the gear pump 4 was selected so that the total fineness of the obtained polyamide 56 fiber was 1400 dtex. The yarn 9 was cooled and solidified by the uniflow cooling device 8, and the non-hydrous oil agent was supplied by the oil supply device (oiling roller) 10. After taking up with the 1st roll 11 (mirror surface), it extended | stretched and heat-set according to the speed ratio between the rolls between the 1st-5th rolls 11-15 (2nd-5th rolls are satin). And after relaxing by the speed ratio of the 5th roll 15 and the 6th roll 16 (6th roll is satin), entanglement is provided with the entanglement nozzle 17, and winding tension | tensile_strength is 0.08- with the winder 18. The cheese package 19 was obtained by controlling the tension so as to be in the range of 0.1 cN / dtex. At this time, the overall draw ratio was adjusted so that the obtained polyamide 56 fiber had an elongation of 4.68 cN / dtex stress at 13%. Then, a 1400 dtex 200 filament polyamide 56 fiber was obtained which was subjected to spinning, stretching and heat treatment in one step. When 100 kg of polyamide 56 fiber was produced, yarn breakage did not occur, and the yarn production was excellent. The properties of the polyamide 56 fiber of Example 1 are shown in Table 1.

The conditions for melt spinning, stretching, and heat treatment are as follows.
・ Single axis extruder temperature: 280 ℃
Spinning temperature (spin block temperature): 285 ° C
Filter layer: φ2 mm glass beads filled Filter: 15 μm non-woven filter Filter base: Hole diameter 0.3 mm, hole depth 0.6 mm, hole number 200
・ Discharge rate: 476 g / min (1 pack 1 yarn, 200 filaments)
Cooling method: Fiber discharged from the die is cooled with cooling air by a uniflow chimney with a cooling length of 1 m, cooling air temperature and humidity 20 ° C RH 55%, wind speed 0.4 m / sec, and the cooling start position is 0.3 m below the die surface.
-Melt spinning, drawing environment: 25 ° C RH 55%
Oil: A mixture of 25 parts by weight of a fatty acid ester, a nonionic surfactant, an anionic surfactant and a modified silicone as an active ingredient of an oil, diluted with 75 parts by weight of mineral oil having 14 carbon atoms. The amount of adhesion is adjusted so that components other than mineral oil adhere to 1 wt% of the fiber weight.
・ First roll (take-off roll) temperature: 25 ° C.
-Second roll temperature: 55 ° C
-Third roll temperature: 145 ° C
-Fourth roll temperature: 210 ° C
-5th roll (final heating roll) temperature: 230 degreeC
-Sixth roll temperature: 25 ° C
-1st roll (take-off roll) speed: 1000 m / min-2nd roll speed: 1020 m / min-3rd roll speed: 2222 m / min-4th roll speed: 2666 m / min-5th roll (final heating roll) speed : 3733 m / min · Sixth roll speed: 3434 m / min · Winding speed: 3400 m / min · Total draw ratio: 3.4 times (ratio between _{first and} second rolls r ₁ : 1.02 times, second and third between rolls magnification _r 2: 2.23-fold, between the first 3-4 rolls magnification _r 3: 1.2 times, between 4 to 5 rolls magnification _r 4: 1.4, between the first 5-6 rolls relaxation ratio _{r 5} : 0.92 times).
-Drawing ratio at a drawing temperature of 100 to 245 ° C: 1.68
-Entanglement pressure air: 0.2 MPa

  As shown in Table 1, the polyamide 56 fiber of Example 1 has a low elongation of 4.68 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes, which is as low as 16%. The fiber was not easily deformed by external force. By adopting the preferred production conditions in the present invention, moisture absorption of the fiber in the melt spinning and drawing process is suppressed, orientation crystallization is promoted in the drawing and heat treatment, and the thermal mobility of the amorphous chain in the fiber is increased. This is due to the restrained effect. The elongation at the time of 4.68 cN / dtex stress was 13%, the dry yield was 2.7%, the strength was 8.6 cN / dtex, and the heat resistant strength retention was 83%.

  Next, two twisted yarns in which the polyamide 56 fiber was subjected to a lower twist (Z twist) were prepared, and an upper twist (S twist) was applied while combining them to obtain a raw cord having various twisted structures. The number of lower twists (Z twist) and the number of upper twists (S twist) were both 40 t / 10 cm, the twist coefficient of the upper twist part was 2008, and the twist coefficient of the lower twist part was 1420. Then, an adhesive was applied to the raw cord using a “Computerator” dipping machine manufactured by Ritzler, followed by heat treatment. As the adhesive, RFL (solid content concentration: 10%) produced in Production Example 8 was used, and the liquid draining conditions were adjusted so that the adhesion amount was 5% by weight.

  The heat treatment conditions were as follows: the atmosphere temperature of the drying furnace was 130 ° C., the passage time was 120 seconds, and a constant length heat treatment was performed, followed by a heat treatment furnace having an atmosphere temperature of 230 ° C. for 60 seconds, followed by a stretch heat treatment. . The stretch stress at the outlet of the heat treatment furnace was adjusted so that the elongation at the time of the 2.34 cN / dtex stress of the cord obtained at this time was 10%. The stretch stress in Example 1 was 1.5 cN / dtex. Next, in a heat treatment furnace for performing a relaxation heat treatment, the atmosphere temperature was set to 225 ° C., and the sample was passed for 60 seconds with a relaxation stress of 0.5 cN / dtex and wound.

  The resulting rubber-reinforced cord has an elongation at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes of 15.2%, a strength of 7.1 cN / dtex, and an elongation at the time of 2.34 cN / dtex stress. Of 10%, elongation of 25%, and dry yield of 4.7%. The rubber reinforcing cord had a rubber adhesiveness (adhesive strength) of 190 N / 10 mm and a fatigue resistance (tube fatigue strength, GY method) of 1712 minutes.

  A radial tire (tire size) using the rubber reinforced cord of Example 1 as a carcass ply by a normal tire manufacturing process, except that post-cure inflation for preventing the cord from shrinking in the cooling step after molding the tire was omitted. 1000R20, 14PR). That is, a tire bag was made with the rubber-reinforced cord, and ends were joined on a drum molding machine to form a cylindrical carcass ply. Next, a belt ply, tread rubber, and side rubber are overlapped on the outside of the carcass ply to form a green tire, and the green tire is placed in a mold, pressurized with steam from the inner surface of the green tire, and the cord is stretched Then, vulcanization molding was performed at a mold temperature of 150 ° C. for 30 minutes. After the vulcanization time had elapsed, the tire was cooled to obtain a tire. At this time, 1400T / 2 rubber reinforcing cords of the present invention were used for the carcass ply, arranged at an angle of 90 ° with respect to the equator plane of the tire, the number of unit cords was 28 ends, and the number of plies was 3 plies. The tread belt ply uses a steel cord of 3 × 0.20 + 6 × 0.38 and is arranged at an angle of 20 ° with respect to the equator plane of the tire. The number of unit cords is 13 ends, and the number of plies is 3 Ply.

  The tire thus obtained was a tire in which the dimensional increase rate of the tire after air filling and the dimensional increase rate of the tire after running the drum were both small, and the dimensional change hardly occurred even when external force or heat was applied. . For this reason, the tire has excellent running stability even in high-speed cornering running.

  The rate of increase in the size of the tire after air filling and the rate of increase in the size of the tire after running the drum are both small at the time of 2.34 cN / dtex stress after 150 ° C. for 30 minutes of dry heat treatment of the rubber reinforcing cord of Example 1. This is considered to be a result of a synergistic effect of low elongation of the rubber and high rubber adhesion (adhesive strength). In addition to the above, the rubber reinforced cord is a rubber reinforced cord excellent in fatigue resistance (tube fatigue strength, GY method) because of excellent balance in strength, heat resistant strength retention, and the like.

(Reference Example 1)
Attempt to produce 1400 dtex, 200 filament polyamide 66 fiber in the same manner as in Example 1 except that the polyamide 66 resin obtained in Production Example 7 was used and the uniaxial extruder temperature was 290 ° C. and the spinning temperature was 300 ° C. However, on the 4th roll, the 5th roll (final heating roll), and the 6th roll (relaxing roll), the running of the yarn was not stable, and yarn breakage occurred frequently. The obtained polyamide 66 fiber had a lot of fluff and was not at a level for subsequent evaluation. For this reason, the speed and discharge amount of each roll were changed, and a polyamide 66 fiber having an elongation of 13% at 4.68 cN / dtex stress and 1400 dtex, 200 filaments was obtained. Using the polyamide 66 fiber of Reference Example 1, a rubber reinforced cord made of polyamide 66 fiber and having an elongation at the time of 2.34 cN / dtex stress of 10% was produced in the same manner as in Example 1, and the cord was formed into a carcass. A tire used as a ply was produced. The results of Reference Example 1 are shown in Table 1 in comparison with Example 1. The conditions changed from Example 1 are described below.

Reference example 1
・ Single axis extruder temperature: 290 ℃
Spinning temperature (spin block temperature): 300 ° C
・ Discharge rate: 392 g / min (1 pack 1 yarn, 200 filaments)
-1st roll (take-off roll) speed: 380 m / min-2nd roll speed: 388 m / min-3rd roll speed: 1748 m / min-4th roll speed: 2010 m / min-5th roll (final heating roll) speed : 2211 m / min, sixth roll speed: 2034 m / min, winding speed: 2014 m / min, total draw ratio: 5.3 times (ratio between first and second rolls r1: 1.02 times, second and third rolls) Magnification ratio r2: 4.51 times, Magnification ratio between third and fourth rolls r3: 1.15 times, Magnification ratio between fourth and fifth rolls r4: 1.1, Relaxation ratio between fifth and sixth rolls r5: 0.92 times ).
-Drawing ratio at a stretching temperature of 100 to 245 ° C: 1.27

  The rubber reinforced cord of Example 1 is higher in elongation at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes than that of Reference Example 1, but the dimensional increase rate of the tire after air filling, And the dimensional increase rate of the tire after running the drum was the same. This is considered to be because efficient reinforcement was achieved in Example 1 due to a synergistic effect with rubber adhesion (adhesive force) higher than that in Reference Example 1. In addition, the rubber reinforced cord of Example 1 was a tire cord having fatigue resistance superior to that of Reference Example 1 and having excellent durability.

  Further, as can be seen from a comparison between Example 1 and Reference Example 1, it can also be seen that the preferred production conditions differ between the polyamide 56 fiber and the polyamide 66 fiber.

  This is presumably because the polymer of the polyamide 66 fiber has high crystallinity, and if the take-up speed is increased, spherulites are formed in the fiber, and stretching stress concentrates on the crystals and fluff is likely to occur. Further, since spherulites are likely to be formed even on a roll heated to 100 to 245 ° C., it is considered that fluff is likely to occur when high magnification stretching is performed at the stretching temperature. On the other hand, the polyamide 56 fiber has a low crystallinity and a high hygroscopicity, so the crystals formed on the spinning line are fine, and the fine crystals are spherical on the roll heated to 100 to 245 ° C. Since it is difficult to form crystals, it is considered preferable to increase the take-up speed and increase the draw ratio in the drawing temperature range.

(Comparative Example 1)
With reference to Example 1 of Cited Document 2, polyamide 56 fibers of 1400 dtex 200 filaments were obtained using the apparatus shown in FIG. At this time, the polyamide 56 fiber discharged from the die was water-cooled and solidified, the take-up speed was 24 m / min, and a steam generator was used as the first-stage drawing heat source. Other spinning conditions are shown below. In the spinning process, yarn breakage occurred seven times, and the spinnability was poor. The production conditions changed from Example 1 are shown below. The results of Comparative Example 1 are shown in Table 1.
・ Discharge rate: 20.2 g / min (1 pack 1 yarn, 200 filaments)
Cooling: Uses 0.1 wt% ethylenebis stearamide aqueous solution. The liquid temperature is 20 ° C., the distance between the lower surface of the base and the water surface is 20 mm, and the cooling length is 100 mm.
・ First roll (take-off roll) temperature: 25 ° C.
・ Steam heating device (atmosphere temperature): 98 ℃
-Second roll temperature: 25 ° C
・ Hot air drawing tank (atmosphere temperature): 172 ° C
-Third roll temperature: 25 ° C
・ Hot air drawing tank (atmosphere temperature): 168 ° C
-Fourth roll (final roll) temperature: 25 ° C
-1st roll (take-up roll) speed: 24.6 m / min-2nd roll speed: 86 m / min-3rd roll speed: 146 m / min-4th roll speed: 146 m / min-Winding speed: 144 m / min -Overall draw ratio: 5.93 times (first to second roll ratio r ₁ : 3.5 times, second to third roll ratio r ₂ : 1.7 times, third to fourth roll ratio r ₃ : 1x).
-Drawing ratio at a stretching temperature of 100 to 245 ° C: 1.7 times

  Since the polyamide 56 fiber of Comparative Example 1 was a fiber having a strength of 8.8 cN / dtex and a high transparency, Example 1 of Cited Document 2 could be reproduced. However, the elongation at the time of 4.68 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes was as extremely high as 29%, and the fiber after being exposed to heat was easily deformed when an external force was applied. Since the dry yield was as high as 14.2%, it was a fiber in which the oriented amorphous chains relaxed when heat was applied.

  This is because the fiber is cooled and solidified by water cooling and taken up at a low speed, so the fiber absorbs moisture at the stage of undrawn yarn and contains a lot of water, and the intermolecular interaction is lowered and amorphous in the drawing process. This is probably because the chains could not be oriented uniformly. Also, steam is used as a drawing heat source, and the maximum heat treatment temperature is as low as 210 ° C. or lower, so that it is considered that the oriented fiber is not sufficiently oriented and crystallized.

  A rubber-reinforced cord was produced in the same manner as in Example 1 using the polyamide 56 fiber of Comparative Example 1. The obtained rubber reinforced cord has a high elongation of 2.7.6 cN / dtex after heat treatment at 150 ° C. for 30 minutes, which is 27.6%, and the cord after being exposed to heat is easily deformed by external force. Met. Moreover, since the dry yield was as high as 16%, the heat shrinkage force of the cord was increased in the vulcanization process, and the rubber adhesiveness of the rubber-reinforced cord was inferior to that of Example 1. And since the elongation at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes is high and the rubber adhesiveness is insufficient, the tire produced with the rubber reinforced cord is Both the dimensional increase rate and the dimensional increase rate of the tire after running on the drum were large, and thus the running stability was poor in high speed cornering running. Furthermore, Comparative Example 1 was inferior in fatigue resistance (tube fatigue strength, GY method) as compared with Examples, and was a cord having low durability.

(Comparative Examples 2-3)
In Comparative Example 1, rubber reinforcing cords of Comparative Examples 2 to 3 were obtained in the same manner as Comparative Example 1 except that the stretch stress in the rubber reinforcing cord manufacturing process was changed.
-Stretch stress of Comparative Example 2: 0.5 cN / dtex
-Stretch stress of Comparative Example 3: 1.8 cN / dtex

  The rubber-reinforced cords of Comparative Examples 2 and 3 all had high elongation at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes. Further, since the dry yield was high, it was a rubber-reinforced cord inferior in rubber adhesion as in Comparative Example 1. Therefore, these synergistic effects are inferior to the tire dimensional increase rate after air filling and the tire dimensional increase rate after drum running. Furthermore, the rubber reinforced cords of Comparative Examples 2 and 3 were inferior in fatigue resistance (tube fatigue strength, GY method) as compared with the Examples, and were cords having low durability.

  From Example 1 and Comparative Examples 1 to 3, in order to obtain a rubber-reinforced cord having a low elongation at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes, as in the example, It can be seen that it is important to be composed of polyamide 56 fibers having low elongation at the time of 4.68 cN / dtex stress after dry heat treatment. As can be seen by comparing Comparative Examples 1 to 3, even if rubber reinforcing cords having different elongation at the time of 2.34 cN / dtex stress are formed by means for increasing the stretch stress in the cord manufacturing process, The elongation at the time of 2.34 cN / dtex stress after the dry heat treatment hardly changes.

(Comparative example 4, Examples 2-6)
In Example 1, polyamide 56 fibers of Comparative Example 4 and Examples 2 to 6 were produced in the same manner as in Example 1 except that the roll speed was changed and the take-up speed and the draw ratio were changed. The discharge amount was adjusted so that the polyamide 56 fiber obtained at this time became 1400 dtex-200 filament. Each roll speed of the comparative example 4 and Examples 2-6 is shown below. Using the polyamide 56 fibers obtained in Comparative Example 4 and Examples 2 to 6, rubber reinforced cords and tires were produced in the same manner as in Example 1, and the characteristics thereof were evaluated. The results are shown in Table 2.

Comparative Example 4
First roll (take-off roll) speed: 24 m / min Second roll speed: 24.5 m / min Third roll speed: 93 m / min Fourth roll speed: 111.6 m / min Fifth roll (final Heating roll) speed: 156.3 m / min. Final roll (relaxing roll) speed: 143.8 m / min. Winding speed: 142.3 m / min. Total draw ratio: 5.93 times (between first and second rolls) Magnification r ₁ : 1.02 times, magnification between second and third rolls r ₂ : 3.8 times, magnification between _{third and} fourth rolls r ₃ : 1.2 times, magnification between _{fourth and} fifth rolls r ₄ : 1 .4, Relaxation ratio between rolls 5 and 6 r ₅ : 0.92 times)
-Drawing ratio at a stretching temperature of 100 to 245 ° C: 1.68 times.

Example 2
・ First roll (take-off roll) speed: 400 m / min ・ Second roll speed: 408 m / min ・ Third roll speed: 1281 m / min ・ Fourth roll speed: 1537 m / min ・ Fifth roll (final heating roll) speed : 2152 m / min. Final roll (relaxing roll) speed: 1980 m / min. Winding speed: 1960 m / min. Overall draw ratio: 4.9 times (ratio between _{first and} second rolls r ₁ : 1.02 times, No. ₁ 2 to 3 roll ratio r ₂ : 3.14 times, 3rd to 4th roll ratio r ₃ : 1.2 times, 4th to 5th roll ratio r ₄ : 1.4, relaxed between 5th and 6th rolls magnification _r 5: 0.92 times)
-Drawing ratio at a stretching temperature of 100 to 245 ° C: 1.68 times.

Example 3
First roll (take-off roll) speed: 1500 m / min Second roll speed: 1530 m / min Third roll speed: 2647 m / min Fourth roll speed: 3176 m / min Fifth roll (final heating roll) speed : 4447 m / min. Final roll (relaxing roll) speed: 4091 m / min. Winding speed: 4050 m / min. Overall draw ratio: 2.7 times (ratio between _{first and} second rolls r ₁ : 1.02 times, No. ₁ 2 to 3 roll magnification r ₂ : 1.73 times, 3rd to 4th roll magnification r ₃ : 1.2 times, 4th to 5th roll magnification r ₄ : 1.4, 5th to 6th roll relaxation magnification _r 5: 0.92 times)
-Drawing ratio at a stretching temperature of 100 to 245 ° C: 1.68 times.

Example 4
-First roll (take-off roll) speed: 2500 m / min-Second roll speed: 2550 m / min-Third roll speed: 3104 m / min-Fourth roll speed: 3725 m / min-Fifth roll (final heating roll) speed : 5215 m / min. Final roll (relaxing roll) speed: 4798 m / min. Winding speed: 4750 m / min. Total draw ratio: 1.9 times (ratio between _{first and} second rolls r ₁ : 1.02 times, No. ₁ 2 to 3 roll ratio r ₂ : 1.22 times, 3rd to 4th roll ratio r ₃ : 1.2 times, 4th to 5th roll ratio r ₄ : 1.4, 5th to 6th rolls relaxed magnification _r 5: 0.92 times)
-Drawing ratio at a stretching temperature of 100 to 245 ° C: 1.68 times.

Example 5
・ First roll (take-off roll) speed: 3500 m / min ・ Second roll speed: 3570 m / min ・ Third roll speed: 3743 m / min ・ Fourth roll speed: 4117 m / min ・ Fifth roll (final heating roll) speed : 5774 m / min. Final roll (relaxing roll) speed: 5303 m / min. Winding speed: 5250 m / min. Overall draw ratio: 1.5 times (ratio between _{first and} second rolls r ₁ : 1.02 times, No. ₁ 2 to 3 roll magnification r ₂ : 1.1 times, 3rd to 4th roll magnification r ₃ : 1.1 times, 4th to 5th roll magnification r ₄ : 1.4, 5th to 6th roll relaxation magnification _r 5: 0.92 times)
-Drawing ratio at a stretching temperature of 100 to 245 ° C: 1.54 times.

Example 6
-1st roll (take-off roll) speed: 4500 m / min-2nd roll speed: 4590 m / min-3rd roll speed: 4866 m / min-4th roll speed: 5352 m / min-5th roll (final heating roll) speed : 6423 m / min. Final roll (relaxing roll) speed: 5909 m / min. Winding speed: 5850 m / min. Total draw ratio: 1.3 times (ratio between _{first and} second rolls r ₁ : 1.02 times, No. ₁ 2 to 3 roll ratio r ₂ : 1.06 times, 3rd to 4th roll ratio r ₃ : 1.1 times, 4th to 5th roll ratio r ₄ : 1.2, 5th to 6th rolls relaxed magnification _r 5: 0.92 times)
-Drawing ratio at a stretching temperature of 100 to 245 ° C: 1.32 times.

  As can be seen by comparing Examples 1 to 6 and Comparative Example 4, the polyamide 56 fiber obtained by adopting the preferred production method in the present invention is 4.68 cN / dtex after dry heat treatment at 150 ° C. for 30 minutes. It can be seen that the elongation under stress is low. The rubber-reinforced cord made of the fiber has a low elongation at the time of 2.34 cN / dtex stress after the dry heat treatment, so that it is embedded in the rubber and exposed to heat in the vulcanization process, drum running, etc. However, it is a cord that is difficult to be deformed by an external force, and sufficient rubber adhesion is exhibited due to low dry yield. Therefore, it can be seen that, due to these synergistic effects, an excellent reinforced rubber can be obtained in which the rate of increase in the size of the tire after running the drum is small after air filling.

  In other words, in the polyamide 56 fiber manufacturing process, by setting the take-up speed to 0.4 km / min or more, moisture absorption on the spinning line can be suppressed, and the amorphous chain can be easily oriented in the drawing process. It is considered that fine crystals are appropriately formed in advance in the drawn yarn, and the fine crystals serve as nuclei to promote oriented crystallization, so that a highly oriented amorphous fiber is obtained. Therefore, the higher the take-up speed, the lower the elongation at the time of 4.68 cN / dtex stress after the dry heat treatment at 150 ° C. for 30 minutes.

  On the other hand, by setting the take-up speed to 4 km / min or less, polyamide 56 fibers having improved manufacturing process passability and excellent strength were obtained. That is, by adopting more preferable take-up speed conditions in the present invention, the fiber was excellent in balance in elongation and strength at 4.68 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes.

  And the rubber reinforcement cord of Example 1 was excellent in a good balance in elongation, strength, and rubber adhesion at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes. Compared to the rubber reinforced cord, the rubber reinforced cord has excellent fatigue resistance.

  The fiber of Comparative Example 4 was lower in elongation at the time of 4.68 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes than that of Comparative Example 1 due to the effect of cooling and solidifying with cooling air. However, it was still insufficient. For this reason, the rubber-reinforced cord of Comparative Example 4 has a high degree of elongation at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes, and also has a high dry yield and inferior rubber adhesion. The dimensional increase rate of the tire after air filling and after running the drum was large. Further, the cord was inferior in fatigue resistance.

(Example 7, Comparative Example 5)
In Example 1, polyamide 56 fibers of Example 7 and Comparative Example 5 were obtained in the same manner as Example 1 except that the roll speed was changed and the draw ratio between the rolls was changed. And the rubber reinforcement cord and the tire were manufactured like Example 1 using this fiber. The roll speed conditions of Example 7 and Comparative Example 5 are described below. The results of Example 7 and Comparative Example 5 are shown in Table 3 in comparison with Example 1.

Example 7
・ First roll (take-off roll) speed: 1000 m / min ・ Second roll speed: 1020 m / min ・ Third roll speed: 2705 m / min ・ Fourth roll speed: 3246 m / min ・ Fifth roll (final heating roll) speed : 3733 m / min. Final roll (relaxing roll) speed: 3434 m / min. Winding speed: 3400 m / min. Total draw ratio: 3.4 times (ratio between _{first and} second rolls r ₁ : 1.02 times, No. ₁ 2 to 3 roll ratio r ₂ : 2.65 times, 3rd to 4th roll ratio r ₃ : 1.2 times, 4th to 5th roll ratio r ₄ : 1.15, relaxed between 5th and 6th rolls magnification _r 5: 0.92 times)
-Drawing ratio at a stretching temperature of 100 to 245 ° C: 1.38 times.

Comparative Example 5
First roll (take-off roll) speed: 1000 m / min Second roll speed: 1020 m / min Third roll speed: 3232 m / min Fourth roll speed: 3555 m / min Fifth roll (final heating roll) speed : 3733 m / min. Final roll (relaxing roll) speed: 3434 m / min. Winding speed: 3400 m / min. Total draw ratio: 3.4 times (ratio between _{first and} second rolls r ₁ : 1.02 times, No. ₁ 2 to 3 roll ratio r ₂ : 3.17 times, 3rd to 4th roll ratio r ₃ : 1.1 times, 4th to 5th roll ratio r ₄ : 1.05, relax between 5th and 6th rolls magnification _r 5: 0.92 times).
-Drawing ratio at a stretching temperature of 100 to 245 ° C: 1.16 times

  As can be seen from the results of Examples 1 and 7 and Comparative Example 5, the polyamide 56 fiber obtained by the preferred production method of the present invention has an elongation of 4.68 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes. You can see that the degree is low. The rubber reinforced cord made of the fiber has a low elongation at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes, so it is embedded in rubber and exposed to heat during the vulcanization process, drum running, etc. In addition to being a cord that is not easily deformed by an external force even after being damaged, sufficient rubber adhesion is exhibited due to low dry yield. Due to these synergistic effects, the rubber reinforcing cord of Example 1 was the rubber reinforcing cord having the smallest dimensional increase rate of the tire after air filling and the dimensional increasing rate of the tire after running the drum, that is, a high reinforcing effect. . At the same time, the rubber reinforced cord of Example 1 was excellent in fatigue resistance.

  The polyamide 56 fiber heated at a stretching temperature of 100 to 245 ° C. has a moderate thermal motion so that water that has previously absorbed moisture is efficiently removed out of the fiber and the amorphous chain does not cause orientation relaxation. It has sex. Therefore, it is considered that when the film is stretched at a stretching ratio of 1.3 times or more at the stretching temperature, the stretching stress is uniformly transmitted to the amorphous chain, the amorphous chain is uniformly oriented, and the oriented crystallization is promoted.

(Examples 8 and 9, Comparative Examples 6 and 7)
In Example 1, polyamide 56 fibers of Examples 8 and 9 and Comparative Examples 6 and 7 were obtained in the same manner as Example 1 except that the maximum heat treatment temperature was changed. However, in Comparative Example 7, the polyamide 56 fibers were fused by the final heating roll and the yarn breakage occurred frequently, so that the fibers could not be produced. Then, using the polyamide 56 fibers of Examples 8 and 9 and Comparative Example 6, a rubber reinforcing cord was formed in the same manner as in Example 1, and a tire was manufactured using the rubber reinforcing cord. The maximum heat treatment temperatures of Examples 8 and 9 and Comparative Examples 6 and 7 are described below. The results of Examples 8 and 9 and Comparative Examples 6 and 7 are shown in Table 4 in comparison with Example 1.
High heat treatment temperature, Example 8 220 ° C
-Example 9 240 degreeC
Comparative Example 6 200 ° C
Comparative Example 7 255 ° C

  As can be seen from a comparison between Examples 1, 8, 9 and Comparative Examples 6 and 7, the maximum heat treatment temperature was 210 to 250 ° C., which resulted in 4.68 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes. A polyamide 56 fiber having low elongation and high strength can be obtained with good processability. When the maximum heat treatment temperature is within this range, it is considered that the oriented amorphous is efficiently crystallized in the fiber without relaxing the orientation, and the restraint property of the amorphous chain is enhanced by the crystal.

  The rubber reinforced cord made of the fiber has a low elongation at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes, so it is embedded in the rubber and exposed to heat during the vulcanization process, drum running, etc. In addition to being hard to be deformed by an external force even after a long time, sufficient rubber adhesion is exhibited due to low dry yield. Due to these synergistic effects, the rubber reinforcing cord of Example 1 was a rubber reinforcing cord having the smallest tire size increase rate, that is, a high reinforcing effect. Furthermore, it was a rubber-reinforced cord excellent in fatigue resistance because of excellent balance in elongation, rubber adhesion, and strength after 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes.

(Examples 10 and 11, Comparative Examples 8 and 9)
In Example 1, polyamide 56 fibers of Examples 10 and 11 and Comparative Examples 8 and 9 were obtained in the same manner as Example 1 except that the relaxation ratio was changed. However, in Comparative Example 9, the polyamide 56 fiber was slackened between the fifth roll (final heating roll) and the sixth roll (relaxation roll), and the yarn was severely swayed and the yarn breakage occurred frequently. There wasn't. Then, using the polyamide 56 fibers of Examples 10 and 11 and Comparative Example 8, a rubber reinforcing cord was formed in the same manner as in Example 1, and a tire was manufactured using the rubber reinforcing cord. The relaxation magnifications of Examples 10 and 11 and Comparative Examples 8 and 9 are described below. The results of Examples 10 and 11 and Comparative Examples 8 and 9 are shown in Table 5 in comparison with Example 1.
Relaxation magnification example 10 0.99
Example 11 0.95
Comparative Example 8 0.87
Comparative Example 9 0.82

  As can be seen by comparing Examples 1, 10, 11 and Comparative Examples 8 and 9, the relaxation magnification is 0.95 or less, that is, by applying high relaxation, non-uniform distortion added to the amorphous chain in the stretching process Since the amorphous chains are stabilized by averaging, the dry yield of the fibers is low, and polyamide 56 fibers having low elongation at 4.68 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes can be obtained. I understand. On the other hand, when the relaxation ratio is 0.85 or more, high-strength polyamide 56 fibers can be obtained with good process passability without causing relaxation of the orientation of amorphous chains.

  The rubber reinforcing cords made of the fibers of Examples 1, 10, and 11 are embedded in the rubber because the elongation at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes is low, and the vulcanization process, drum In addition to being hard to be deformed by external force even after being exposed to heat during running, sufficient rubber adhesion was exhibited due to low dry yield. In particular, the rubber reinforcing cords of Example 1 and Example 11 are rubbers having a small dimensional increase rate of the tire after air filling and a small dimensional increase rate of the tire after running the drum, that is, an excellent reinforcing effect. It was a reinforced cord. Furthermore, it was a rubber-reinforced cord excellent in fatigue resistance because of excellent balance in elongation, rubber adhesion, and strength after 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes.

(Comparative Example 10)
In Example 2, after undrawn fiber discharged from the die was taken up, it was wound at 400 m / min without being drawn to obtain a package of undrawn fiber. The undrawn yarn package was stored for 14 days in a temperature and humidity environment of 25 ° C. and RH 55% to adjust the humidity, thereby absorbing the undrawn yarn. Thereafter, the fiber was drawn out from the undrawn yarn package, and drawn at the following roll speed under the same drawing temperature, final heat treatment temperature, and relaxation ratio conditions as in Example 2. Compared with Example 2, the process passability was poor, and yarn breakage occurred frequently, but somehow sampling was possible. And using the fiber of the comparative example 10, it carried out similarly to Example 2, and produced the rubber reinforcement cord and the tire. The results of Comparative Example 10 are shown in Table 6 in comparison with Example 2. In Comparative Example 10, the roll speed when the undrawn yarn is drawn is shown below.

Comparative Example 10
First roll speed: 100 m / min Second roll speed: 102 m / min Third roll speed: 320 m / min Fourth roll speed: 384 m / min Fifth roll speed: 538 m / min Final roll speed: 495m / min, winding speed: 490m / min

  Compared with Example 2, the fiber of Comparative Example 10 was a fiber with high dry yield, high elongation at 4.68 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes, and low strength. Therefore, the cord of Comparative Example 10 was inferior to Example 2 in that the elongation at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes was 20% or more. Moreover, since the dry yield was also high, rubber adhesion was not sufficiently developed. For this reason, the tire of Comparative Example 2 has a large increase in the size of the tire after air filling and a large change in the size of the tire after running the drum. In addition, compared with the rubber reinforced cord of Example 2, all the elongation, rubber adhesion and strength at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes are inferior, and thus the cord is also inferior in fatigue resistance. Met.

  As can be seen from a comparison between Example 2 and Comparative Example 10, by adopting the direct spinning drawing method, the elongation at 4.68 cN / dtex stress after dry heat treatment at 150 ° C. for 30 minutes is low, and the dry yield is low. It can be seen that high-strength polyamide 56 fibers can be obtained with good processability. As a result, a rubber reinforced cord and a reinforced rubber having excellent characteristics were obtained. This is considered to be the effect that the orientation crystallization can be promoted in the stretching process because the fiber can be stretched without being wound up by one end and can be subjected to stretching in a state where moisture absorption of the fiber is suppressed.

Example 12
In Example 1, except that the polyamide 56 resin obtained in Production Example 6 was used, a polyamide 56 fiber, a rubber reinforced cord made of the fiber, and a tire were produced in the same manner as in Example 1. The results of Example 12 are shown in Table 7 in comparison with Example 1. As can be seen from Table 7, when the content of the anti-aging agent of the polyamide 56 fiber of the present invention is in a preferred range, the fiber has a high heat resistance and strength retention. The heat-resistant and strong retention rate of the rubber-reinforced cord made of the fiber was also high, and a rubber-reinforced cord excellent in fatigue resistance was obtained.

It is the figure which compared the relationship between the elongation at the time of 2.34 cN / dtex stress, and the dry yield about the rubber reinforcement cord of Example 1 and Comparative Examples 1-3. It is a schematic diagram of the direct spinning drawing apparatus provided with the uniaxial kneader. It is a schematic diagram of the apparatus used for manufacturing the fiber of the comparative example 1.

Explanation of symbols

1: Hopper 2: 1 axis extruder 3: Polymer piping 4: Gear pump 5: Spin block 6: Spin pack 7: Spinneret 8: Uniflow cooling device 9: Yarn 10: Oil supply device 11: First roll 12: Second Roll 13: Third roll 14: Fourth roll 15: Fifth roll
16: Sixth roll 17: Entangling nozzle 18: Winder 19: Cheese package 20: Water-cooled bath 21: Cooling water 22: Guide roll 1
23: Guide roll 2
24: Guide roll 3
25: Steam generator 26: Dry heat furnace 1
27: Dry heat furnace 2

Claims (7)

  A polyamide 56 fiber characterized by an elongation of 12 to 20% at 4.68 cN / dtex stress after a dry heat treatment at 150 ° C. for 30 minutes.   The polyamide 56 fiber according to claim 1, wherein the strength is 6 to 12 cN / dtex.   A rubber reinforcing cord comprising the polyamide 56 fiber according to claim 1 or 2.   The rubber reinforcing cord according to claim 3, wherein the elongation at the time of 2.34 cN / dtex stress after dry heat treatment at 150 ° C for 30 minutes is 11 to 19%.   The rubber reinforcing cord according to claim 3 or 4, wherein the dry yield is 1 to 10%.   Reinforcing rubber comprising the rubber reinforcing cord according to any one of claims 3 to 5.   After cooling and solidifying the polyamide 56 fiber discharged from the die with cooling air, a non-hydrous oil agent is attached, and after drawing, heat treatment and relaxing treatment with a dry heat source, winding, by direct spinning drawing method In the method for producing the polyamide 56 fiber, the take-up speed is 0.4 to 4 km / min, the draw ratio applied at a draw temperature of 100 to 245 ° C is 1.3 times or more, and the maximum heat treatment temperature is 210 to 250 ° C. A method for producing polyamide 56 fibers, wherein the relaxation ratio is 0.85 to 0.95.

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