JPH0512572B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to flat belts and V-belts such as conveyor belts used in industrial machines. Traditionally, belts of this type have been made with a filament fabric made of synthetic fibers such as aliphatic polyamide, polyethylene terephthalate, or polyvinyl alcohol, and coated with abrasion-resistant rubber or flexible resin. , strong, elongation,
It is hard to say that it is sufficient in terms of chemical resistance, etc. That is, the properties required for flat belts, V-belts, etc. are high strength, low elongation, dimensional stability, and chemical resistance. It goes without saying that high strength is required, and at the same time, moderately low elongation is also required. If the elongation is too high, the belt will sag over time. If the elongation is extremely low, it will be difficult to apply sufficient tension to the belt. To manufacture a high-strength belt, thick denier yarns can be used as warp yarns, but this increases the weight and thickness, which is undesirable in terms of transportation and handling. In order to solve these problems,
In Publication No. 120775, a twisted yarn consisting of fibers mainly composed of polyparaphenylene terephthalamide and fibers mainly composed of polymetaphenylene isophthalamide is used for the warp, and a fiber mainly composed of polymethaphenylene isophthalamide is used as the weft. Belts made of belts have been proposed, but when used for a long period of time, there are problems with abrasion resistance, and the belt wears out at the contact surface between the belt and the belt drive unit, and the strength of the belt gradually decreases. . This is because polyparaphenylene terephthalamide fibers are composed of rigid polymer chains and have low abrasion resistance. On the other hand, in Japanese Utility Model Application Publication No. 52-120774, a core spun yarn consisting of a metal fiber as a core and a wholly aromatic polyamide fiber surrounding the core is used as the warp, and a wholly aromatic polyamide fiber is used as the weft. A woven belt is also provided, but in this case, if the wholly aromatic polyamide fiber is polyparaphenylene terephthalamide fiber, it has the same drawbacks regarding abrasion resistance as described above. Additionally, belts used in industrial machinery may become wet due to various chemicals depending on the industrial field, the most commonly used being acids such as sulfuric acid or alkalis such as caustic soda. In such cases, it has been found that the strength of the polyparaphenylene terephthalamide fibers rapidly decreases due to corrosion by acids, alkalis, etc., and the abrasion resistance significantly decreases. Under these circumstances, the present inventors have developed a belt structure that has high strength and appropriate elongation, resists corrosion by acids and alkalis, and has excellent abrasion resistance and dimensional stability. As a result of intensive research, the present invention was arrived at. That is, the present invention coats a base fabric made of polyhexamethylene adipamide (hereinafter also referred to as nylon 66) fiber dip cord, which exhibits high strength and excellent fatigue resistance, with rubber or flexible resin on one or both sides. The purpose is to provide a belt that will On the other hand, in order to improve these properties of nylon 66 dip cord, as seen in Japanese Patent Application Laid-Open No. 58-60012, after forming an undrawn yarn with a high degree of orientation by using high-speed spinning at a spinning speed of 2000 m/min or more, Nylon 66 fibers for rubber reinforcement have been proposed, which have low shrinkage and improved dimensional stability by stretching. However, although these methods improve dimensional stability, they have the disadvantage of decreasing strength. The inventors of the present invention have carried out intensive research with the aim of obtaining a belt that is made of nylon 66 dip cord that has high strength, high modulus, and excellent dimensional stability, and has low vulcanization deterioration and excellent fatigue resistance. , arrived at the present invention. That is, the above objectives are (1) consisting of a nylon 66 polymer containing 95 mol% or more of hexamethylene adipamide repeating structural units;
Melt-spinning a polyamide having a high degree of polymerization with a relative viscosity of sulfuric acid of 2.8 or more and containing one or more copper salts and/or an inorganic or organic antioxidant other than the copper salt. (2) The spun yarn is taken under conditions such that the birefringence of the undrawn yarn is less than 25×10 ^-3 . (3) After the yarn that has passed through the take-up roll is wound up continuously or once, it is hot-stretched so that the total stretching ratio is 4.0 times or more. (4) The quality of the drawn yarn must meet the following conditions. (E) DT≧10g/d preferably DT≧12g/d (F) 20%≧DE≧8% (G) IS≧35g/d (H) SHD≦15% (5) Drawn yarn (multifilament yarn) A raw cord is created by subjecting the cord to first twisting and final twisting with a twist coefficient of 2000 to 1300, preferably 1800 to 1400. (6) The raw cord or the blind fabric knitted from the raw cord is treated with a dip solution to improve its adhesion to rubber, followed by 0 to 5% hot stretching. (7) This can be achieved by sandwiching the nylon 66 cord fabric (dipped fabric) obtained as described above between sheets of rubber or flexible resin and calendering to form a belt. According to this method, the repeating structural unit of polyhexamethylene adipamide is composed of 95 mol% or more of nylon 66 polymer, has a high polymerization degree of sulfuric acid relative viscosity of 2.8 or more, and has one or more types of polyhexamethylene adipamide. It is made of nylon 66 fiber containing a copper salt and/or an inorganic or organic antioxidant other than the copper salt, and has a twist coefficient of 2000 to 1300, preferably to which a dip liquid is attached to improve adhesion to rubber. teeth
A base fabric using a polycapramide dip cord having a top twist and a first twist of 1800 to 1400, which has the following properties at the same time: high strength, high modulus, and significantly improved dimensional stability and fatigue resistance. In addition, a high-strength belt having one or both sides coated with rubber or flexible resin can be obtained. (B) Breaking strength of dip cord A≧8.5g/d Preferably A≧9.0g/d (B) Intermediate elongation of dip cord B≦8.5% (C) Dry heat shrinkage rate of dip cord C≦6% Preferably C≦ 5% (d) C≦-2B+19 More specifically, the characteristics of the fiber obtained by the method of the present invention and its dimensions will be described in detail. The raw material polymer may contain polyhexamethylene adipamide in 95 mol % or more of the number of repeating units in the molecular chain and less than 5 mol % of the copolymer component. Examples of polyamide components that can be copolymerized include poly-ε-capramide, polyhexamethylene sebamide, polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, and polyxylylene phthalamide. If the copolymer component is contained in an amount of 5 mol % or more, crystallinity and dimensional stability are reduced, which is not preferable. Nylon 66 polymer (hereinafter also referred to as polymer) is preferably a polymer with a high degree of polymerization having a sulfuric acid relative viscosity of 2.8 or more, particularly 3.0 or more for obtaining the high strength yarn of the present invention. Furthermore, since the nylon 66 fiber of the present invention is mainly used for industrial purposes, an antioxidant is added to the polymer in order to provide sufficient durability against heat, light, oxygen, etc. The antioxidants include copper salts such as copper acetate, cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, copper phthalate, copper stearate, and various other antioxidants. Complex salts of copper salts and organic compounds, such as copper complex salts of 8-oxyquinoline copper, 2-mercaptobenzimidazole, preferably cuprous iodide,
Copper acetate, cuprous iodide complex salts of 2-mercaptobenzimidazole, etc., halides of alkali or alkaline earth metals such as potassium iodide, potassium bromide, potassium chloride, sodium iodide, sodium bromide, zinc chloride, chloride Calcium etc., organic halides such as pentaiodobenzene, hexabromobenzene, tetraiodoterephthalic acid,
Methylene iodide, tributylethylammonium iodide, etc., and inorganic and organic phosphorus compounds such as sodium pyrophosphate, sodium phosphite, triphenyl phosphite, 9,10-dihydro-10-
(3',5')-di-t-butyl-4'-hydroxybenzyl)-9-oxa-perphosphaphenanthrene-10-oxide, etc., and phenolic antioxidants such as tetrakis-[methylene -3-
(3,5-di-t-butyl-4-hydroxyphenyl)-propionate]-methane, 1,3,5-
Tri-methyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, n-octadecyl-3-(3,5-di-t-
butyl-4-hydroxyphenyl)-propionate, 4-hydroxy-3,5-di-t-butylbenzyl phosphate diethyl ester, etc., and amine antioxidants such as N,N'-di-β-naphthyl-p-
Phenyl diamine, 2-mercaptobenzimidazole, phenyl-β-naphthylamine, N,
N'-diphenyl-p-phenylenediamine, a condensation reaction product of diphenylamine and allyl ketone,
Preferred are potassium iodide, 2-mercaptobenzimidazole, and the like. The antioxidant can be incorporated during the polyamide polymerization process or by sprinkling on the chips after the polyamide is once made into chips. The content of antioxidant is 10 to 300 ppm as copper for copper salt, preferably 50 to 200 ppm, and 0.01 to 1% for other antioxidants, preferably 0.03 to 0.5%.
is within the range of The antioxidant is preferably a copper salt and another antioxidant, or a combination of two or more thereof. The polyamide dried to a moisture content of 0.1% or less is spun using a melt spinning machine, preferably an extruder type spinning machine. The spinning take-off speed is determined when the birefringence of the collected yarn is 25.
It is set to be less than ×10 ⁻³ , preferably 10×10 ⁻³ or less. The spinning conditions corresponding to the birefringence index include not only the spinning take-off speed but also the nozzle hole diameter,
Distance between nozzle and quench, relative viscosity of polymer,
It can be determined by optimizing a number of factors such as spinning temperature. If the birefringence of the spun yarn is 25×10 ^-3 or more, it will not be possible to stably produce a high-strength yarn with a cutting strength DT of 10 g/d or more. When the molecular weight of the polymer is constant, it is preferable to make the birefringence of the spun yarn as small as possible in order to obtain a high-strength yarn. The stretching method involves, for example, melt-spinning nylon 66 with RV = 3.0, and stretching the resulting yarn with a birefringence index of 5 x 10 ^-3 to 10 x 10 ^-3 either continuously after spinning or after it has been wound once. At this time, preliminary stretching of 1.10 times or less is applied between the undrawn yarn first supply roller and the undrawn yarn second supply roller maintained at 100°C or lower, and then the full stretching is applied between the undrawn yarn first supply roller and the first stretching roller. 4.0% of magnification
It is best to carry out the above first-stage drawing, and if necessary, a high-temperature pressurized steam jet nozzle is provided between the undrawn yarn second supply roller and the first drawing roller to control the nozzle temperature.
High-temperature steam is ejected at 200°C or higher, and the stretching point is fixed near the high-temperature pressurized steam ejection nozzle. Furthermore, when performing the second stage stretching, the atmosphere temperature provided between the first stretching roller and the second stretching roller is 170 to 350.
°C in a slit heater (a heating device that has a slit as a yarn running path, and heats the yarn while running through the slit in a non-contact state: ambient temperature refers to the temperature inside the slit) The thread is
The film is allowed to pass through the film for a period of 0.3 seconds or more, and then subjected to a second stretching roller. At that time, a temperature gradient is provided in the slit heater, so that the atmospheric temperature at the yarn inlet is 160°C or higher and the exit atmospheric temperature is 350°C or lower, and the yarn can stay in an atmosphere of 170 to 350°C for 0.3 seconds or more. It is preferable to allow the thread to pass through the thread. In addition, after the completion of the two-stage stretching, it can be stretched continuously without winding or after winding.
It is also possible to further improve dimensional stability by performing a relaxation treatment of 10% or less at ℃. In order to obtain the high tenacity, low elongation yarn used in the present invention, it is drawn at a high draw ratio of 85% or more of the maximum draw ratio, preferably 90% or more, and the residual elongation is 8 to 20%. The stretching ratio of each sample is basically determined by the degree of orientation of each drawn yarn. Note that the maximum stretching ratio refers to the maximum stretching ratio that can be stretched. The nylon 66 fiber thus obtained has the following properties. (E) DT≧10g/d (F) 20%≧DE≧8% (G) IS≧35g/d (H) SHD≦15% The nylon 66 multifilament yarn obtained above is Twist the yarn according to the usual method,
Use raw code. Furthermore, the raw cord or the blind fabric woven from the raw cord is treated with a dip solution to improve its adhesion to rubber, followed by hot stretching. The inventors of the present invention have carefully studied the process from making these raw cords to dip processing, and have made the dip cords highly strong, have low intermediate elongation, and have a low shrinkage rate, which cannot be achieved with conventional nylon 6 dip cords. The present inventors have discovered that excellent performance can be achieved, leading to the present invention. That is, the high strength, low elongation nylon 66 used in the present invention
In the case of fibers, the twist coefficient (T x √) is usually 2000 to 2200 (for example, 840d/2 twist
47turn/10cm), the strength utilization rate of the raw cord will decrease, but the twist coefficient should be set at 1300-2000, preferably 1400-2000.
When set in the range of 1800, the strength utilization rate is very excellent, and by lowering the hot stretch ratio in the dip process to 0 to 5%, a dip cord with a low shrinkage rate and low intermediate elongation can be obtained. The intermediate elongation is a measure corresponding to the modulus of the cord, and the fact that the intermediate elongation of the dip cord is low indicates that the modulus of the cord is high. Normally, when manufacturing nylon 66 dip cord, the hot stretch ratio in the dip process is 7% to 12% to increase the modulus of the cord.
Set to . On the other hand, in general, when the hot stretch ratio in the dip process is increased, the shrinkage rate of the dip cord increases and the dimensional stability decreases. Therefore, conventional nylon 66 dip cords have not been able to satisfy both dimensional stability and high modulus. The feature of the present invention is that by elongating the molecular chains more than conventional nylon 66 high-strength yarn at the high-strength yarn production stage, a high-strength, high-modulus, low-elongation yarn is already created, and after twisting, In the dip process, the modulus of the dip cord is increased by hot stretching. In other words, since there is no need to lower the intermediate elongation, the load on the cord during the dip treatment process is reduced, resulting in low shrinkage and low intermediate elongation (high modulus) that were previously unimaginable for nylon 66. The reason is that we have achieved a high-strength dip cord. None of the conventional nylon 66 dip cords had a breaking strength A of 8.5 g/d or more, and an intermediate elongation B and a dry heat shrinkage C satisfying the following formulas. (See Figure 1) (b) B≦8.5% (c) C≦6% (d) C≦-2B+19 These dip cord characteristics are based on twist coefficients of 2000 to 2000.
In the low twist number region of 1300, more preferably 1800 to 1400, the hot stretch ratio in the dip process is 0 to 5.
This can only be achieved under low stretch conditions of %. Reducing the number of twists has the advantage of increasing the twisting speed and reducing costs, but according to conventional knowledge, it has the disadvantage of decreasing fatigue resistance. However, since the dip cord of the present invention satisfies the formulas (a) to (d), even a cord with a low twist has a fatigue resistance higher than that of a cord with a conventional number of twists. These properties are evident, for example, in the high residual strength after disk fatigue tests. The rubbery or flexible resin referred to in the present invention is
Polyurethane resin, styrene-butadiene rubber,
Chloroprene rubber, ethylene-propylene rubber,
Diene rubber etc. Flat belts such as conveyor belts used in industrial machinery are driven either by having only one side pressed against a belt drive roller or by having both sides of the belt pressed by nip rollers.
Depends on the drive system of the machine. Therefore, the resin coating is performed by coating, impregnating, or spraying resin on one or both sides of the belt, depending on the purpose. Alternatively, the resin film may be stacked on the base fabric and bonded by heating and pressing. As a result of the belt of the present invention being constructed as described in the claims, it is stronger than conventional belts, has an appropriate elongation suitable for the application, and has high abrasion resistance. The belt also has chemical resistance. Below, methods for measuring the main parameters used to identify the structure and measure the physical properties of the fibers constituting the present invention will be described. <Relative viscosity measurement method> Prepare a sample solution by dissolving the sample in 96.3±0.1% by weight reagent special grade concentrated sulfuric acid so that the polymer concentration is 10mg/ml, and incubate in water at a temperature of 20℃±0.05℃. Measure the relative viscosity of the solution using an Ostwald viscometer with 6-7 seconds. For measurement, use the same viscometer and use the same 20% sulfuric acid as when preparing the sample solution.
The relative viscosity RV is calculated from the ratio of the falling time T ₀ (seconds) for ml and the falling time T ₁ (seconds) for 20 ml of the sample solution using the following formula. RV=T ₁ /T ₀ <Method for measuring birefringence (Δn)> Nikon polarizing microscope POH type Leitz Beretsk convenser was used, and the light source was a spectral light source activation device (Toshiba SLS-3-B type). (Na light source). A sample cut at an angle of 45 degrees to the fiber axis with a length of 5 to 6 mm is placed on a glass slide with the cut side facing up. Place the sample slide glass on the rotating stage, adjust the rotating stage so that the sample is at a 45 degree angle to the polarizer, insert the analyzer and set the dark field, and then turn on the compensator.
30 and count the number of stripes (n pieces). Turn the compensator clockwise to mark the point at which the sample first becomes darkest (a), and turn the compensator counterclockwise to mark the point at which the sample first becomes darkest (mark b). After measuring (read up to 1/10 scale in both cases), return the compensator to 30, remove the analyzer, measure the diameter d of the sample, and calculate the birefringence (Δn) based on the formula below. (Average value of 20 measurements). Δn=Γ/d (Γ=nλ ₀ +ε) λ ₀ =589.3mμ ε: Calculated from C/10000 and i in the Leitz compensator manual i: (a-b) (: Difference in compensator reading ) <Method for measuring strength and elongation properties of fibers and cords> Based on the definition of JIS-L1017. Take the sample in a skein shape and store it in a temperature and humidity controlled room at 20℃ and 65%RH for 24 hours.
After standing for a period of time, a test length of 20
cm, and the tensile speed was 20 cm/min. <Formula for calculating twist coefficient> Twist coefficient K = Number of twists x (denier) ^1/2 Number of twists: turn/10cm <Method for measuring disk fatigue> Using an ordinary disk fatigue tester, embed dip cord and vulcanize. The prepared test piece was set and heated at 2500 rpm under a compression ratio of 12.5% and an elongation ratio of 6.3%.
After being subjected to forced fatigue by rotation at a speed of 48 hours,
The dip cord was removed from the rubber and its residual strength was measured. <Measurement method of intermediate elongation> According to the definition of JIS-L1017. Measure the elongation rate under a constant load W (Kg). The elongation measurement conditions are similar to those for strength and elongation properties. The constant load W is defined by the following formula. W=4.5×d ² /d ¹ d ² : sample denier, d ¹ : reference denier, which is 840 denier for yarn and 1680 denier for cord. <Measurement method of dry heat shrinkage rate SHD> Take a sample in the form of a skein, leave it in a temperature and humidity controlled room at 20℃ and 65%RH for more than 24 hours, and then 0.1 of the sample
Length l ₀ measured by applying a load equivalent to g/d
The sample was placed in an oven at 150℃ under no tension for 30 minutes.
After being left for a few minutes, it was taken out from the oven and left in the above temperature and humidity control room for 4 hours, and the above load was applied again to calculate the measured length _l1 using the following formula. Dry heat shrinkage rate SHD=l ₀ −l ₁ /l ₀ ×100 (%) <Production example> Nylon 66 with the relative viscosity shown in Table 1 was used as the raw material, and spinning was performed under the conditions shown in the table. An undrawn yarn with the birefringence Δn (measured after standing for 24 hours at 20° C. and 65% RH) and relative viscosity was obtained. In addition, during spinning, an appropriate amount of spinning oil was applied to the surface of the yarn before taking off the undrawn yarn. The obtained undrawn yarn was drawn under the conditions shown in Table 2 to obtain drawn yarn having the quality shown in Table 3. Table 3 shows the yarn quality of a commercially available polyhexamethylene adipamide fiber for tire cord as Comparative Example 1. Next, the drawn yarns of Example 1 and Comparative Example 1 were separately combined to obtain multifilament yarns of 840 denier.

【table】

【table】

【table】

[Table] 47T/10cm and 42T/
10cm, and 37T/10cm twisted and untwisted
840d/2-ply 2-strand cord. The raw cord thus obtained was immersed in a nylon 6 dip solution consisting of a resorcinol-formalin latex solution, and then dried with hot air at 120° C. for 2 minutes under a 1.5% stretch. Subsequently, it is introduced into the hot stretch zone,
After 1%, 3%, and 7% hot stretching in heated air at 200°C, a dip cord was produced by further heat-treating at a fixed length for 36 seconds in heated air at 200°C. The properties of the raw cord and dip cord according to this production example were as shown in Table 4. The dip cord obtained in the present invention has significantly improved strength compared to the dip cord obtained in the comparative example, and has low intermediate elongation and low dry heat shrinkage, which is a measure of dimensional stability, and has a low dry heat shrinkage rate in the low twist region. It also has excellent fatigue resistance.

【table】

[Table] Next, the dip cords obtained in the ratio 7 of Invention 1 and Comparative Example 1 in Table 4 were used as the warp yarns, and the dip cords made of high-strength polyester fibers were used as the weft yarns to form a double twill structure. A belt was prepared by coating both sides with the material, and its strength and elongation characteristics were compared. Table 5 shows the comparison results of the thread usage, density, and physical properties of the obtained products of the base fabrics used.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a diagram showing dip code characteristics of the present invention. 1...This invention.

Claims (1)

[Scope of Claims] 1 Hexamethylene adipamide has a repeating structural unit of 95 mol % or more, a sulfuric acid relative viscosity of 2.8 or more, and a high degree of polymerization, and one or more copper salts and/or the above-mentioned Ply-twisted and polyhexamethylene adipamide fibers containing inorganic or organic antioxidants other than copper salts, with a twist coefficient of 2000 to 1300 and coated with a dip liquid to improve adhesion to rubber. A polyhexamethylene adipamide dip cord with a first twist, which has high strength and high modulus, and has significantly improved dimensional stability and fatigue resistance. A high-strength belt made of a base fabric coated with rubber or flexible resin on one or both sides. (a) Breaking strength of dip cord A≧8.5g/d (b) Intermediate elongation of dip cord B≦8.5% (c) Dry heat shrinkage rate of dip cord C≦6% (d) C≦−2B+19 2. Scope of Claims The high-strength belt using a polyhexamethylene adipamide dip cord according to item 1, wherein the dip cord has a breaking strength of 9.0 g/d or more and a dry heat shrinkage rate of the dip cord of 5% or less. 3. A high-strength belt using a polyhexamethylene adipamide dip cord according to claim 1 or 2, characterized in that the dip cord has a twist coefficient of 1800 to 1400. 4. Claims 1 to 3 in which the rubbery or flexible resin is one or a combination of two or more selected from the group consisting of polyurethane resin, styrene-butadiene rubber, chloroprene rubber, ethylene propylene rubber, and diene rubber. The high-strength belt described in any of the above.