JPS60234150A - High-tenacity belt - Google Patents

Abstract

PURPOSE:To get a belt which is superior in fatigue-durability, by coating a base cloth which is woven of polyhexamethylene adipic acid amide fiber dip cord, with rubber of plastic resin. CONSTITUTION:Polyamide, which is formed of nylons 66 polymer whose hexamethylene adipic acid amide repeated structural unit is more than 95mol%, which is highly polymerized as the sulfuric acid relative viscosity is more than 2.8, and which contains one or plural kinds of copper chloride and/or organic or inorganic antioxidant other than the copper chloride, is meltingly spun. Then, raw cord is made by primarily twisting and finally twisting, at twist coefficient of 2,000-1,300 (1,800-1,400 is preferable), the stretched thread which is formed by heat-stretching the meltingly spun thread, and this cord is treated with dip liquid. The fracture strength A of this nylons 66 dip cord is more than 8.5g/d, its intermediate elongation B is less than 8.5%, and its dry/heat shrinkage C is less than 6%; and formula C<=-2B+19 can be satisfied. Then, one surface or both surfaces of a base cloth which is woven of this cord, is coated with rubber or plastic resin.

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, this type of fabric has been used with a base fabric made of filament fabric made of synthetic fibers such as aliphatic polyamide, polyethylene terephthalate, and polyvinyl alcohol, and coated with abrasion-resistant rubber or flexible resin. However, it is difficult to say that it is sufficient in terms of strength, elongation, chemical resistance, etc. In other words, 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 necessary, but 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. Although thick denier yarns can be used as warp yarns to produce high-strength bells, they increase weight and thickness, which is undesirable in terms of transportation and handling.

In order to solve all these problems,
In Publication No. 75, a twisted yarn consisting of fibers mainly composed of borino rough ethylene terephthalamide and fibers mainly composed of polymetaphenylene isophthalamide is used for the warp, and a fiber mainly composed of polymetaphenylene isophthalamide is used for the weft. A belt has been proposed, but when used for a long period of time, there is a problem 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. All woven belts are provided at the same time, 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. In addition, belts used for industrial root plates are wetted by various chemicals depending on the field of chestnut production, most commonly acids such as sulfuric acid or alkalis such as caustic soda. It has been found that in such cases, the strength of 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 possesses high strength and appropriate elongation, resists corrosion by acids, alkalis, etc., 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 uses 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, and is coated with rubber or flexible resin on one or both sides. The purpose of this invention is to provide a belt made of

On the other hand, in order to improve these properties of nylon 66 dipped cord, high-speed spinning at a spinning speed of 2000''/min or more was used to obtain undrawn yarn with a high degree of orientation, as seen in Japanese Patent Application Laid-Open No. 58-60012. Nylon 66 fibers for rubber reinforcement have been proposed that have low shrinkage and improved dimensional stability by stretching the fibers after stretching.

However, although these methods improved dimensional stability, they had the disadvantage of decreasing strength. With the aim of obtaining a bell (1) which is made of cord and has little vulcanization deterioration and excellent fatigue resistance, we have carried out extensive research and have finally arrived at the present invention.

That is, the above purpose is (1) that the repeating structural unit of hexamethylene adipamide is 9
It is made of nylon 66 polymer with a molten content of 5 or more, has a high degree of polymerization with a relative viscosity of sulfuric acid of 2.8 or more, and contains one or more copper salts and/or an inorganic or organic antioxidant other than the copper salts. (2) The birefringence of the spun yarn Togane undrawn yarn is 25X10.
``The property must be picked up under conditions that are less than ``.

(3) After the yarn passed through the take-up roll is wound up continuously or once, it is hot-stretched so that the total stretching ratio becomes 4.0 times or more.

(4) The quality of the drawn yarn satisfies the following conditions.

(e) DT≧10 f/d preferably DT≧12 f/
d (f) 20%≧DE≧8% ()) IS ≧ 3 5 f/d (e) SHD≦15% (5) Twisting coefficient 2 for drawn yarn (multifilament yarn)
000 to 1300, preferably 1800 to 1400, first twist and final twist to create a raw cord.

(6) The raw cord or the blind fabric knitted from the raw cord is treated with a dip liquid to improve its adhesion to rubber, followed by 0 to 5% hot stretching.

(No) This is achieved by sandwiching the nylon 66 needled fabric (dip-treated fabric) obtained as described above between sheets made of rubber or flexible resin and calendering to completely form the belt. According to the method, polyhexamethylene adipamide is made of a nylon 66 polymer with a repeating structural unit of 95 molti or more, has a high degree of polymerization of sulfuric acid relative viscosity of 2.8 or more, and has 11!Jlr or two or more types. The fiber 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 and is coated with a dip liquid to improve adhesion to rubber.
-1300, preferably 1800-1400, a polycapramide-based dip cord having a twist and a twist of 1,800 to 1,400, which is a polycapramide-based dip cord having high strength, high modulus, and significantly improved dimensional stability and fatigue resistance, simultaneously having the following properties: A high-strength belt can be obtained in which a base fabric using dip cord is coated with rubber or flexible resin on one or both sides. (a) Breaking strength KA of dip cord ≧8.5 f/d
Preferably A≧9°Of/d (b) Intermediate elongation of dip cord B≦8.5% (c) Dry heat shrinkage rate of dip cord 056% Preferably
055%) C≦-2B+19 More specifically, the method of the present invention and the characteristics of the fiber obtained by the method will be described in detail.

The raw material polymer may contain polyhexamethylene adipamide at least 95 moles of repeating units in the molecular chain and less than 5 moles of copolymerization components. Examples of polyamide components that can be copolymerized include poly-ε-capramide, polyhexamethylene 1/ncebacamide, polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, and polyxylylene phthalamide. If the copolymer component is contained in an amount of 5 mol or more, the crystallinity will decrease and the dimensional stability will decrease, 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 g of 2.8 or higher, particularly 3.0 or higher for obtaining the high-strength yarn of the present invention. In addition, since the nylon 66 fiber of the present invention is mainly used for asset applications,
Antioxidants are added to polymers to provide sufficient durability against heat, light, oxygen, etc. Copper salts such as copper acetate, cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, copper phthalate, copper stearate are used as antioxidants. , and complex salts of various copper salts and organic compounds, such as copper complex salts of 8-oxyquinoline copper and 2-mercaptobenzimidazole,
Preferably, cuprous iodide, steel 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, calcium chloride, 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, 9,1o-sivitrho-10-(3',5/-di-t-butyl-4'-human tetraxybenzyl)-9-oxaberphosphaphenanthrene-10- and phenolic antioxidants, such as tetrakis-[methylene-3-(3°10
- 5-di-t-butyl-4-hydroxyphenyl)-propionate-co-methane, 1,3.5-)lymethyl-
2,4,6-)lis(3,5-di-t-butyl-4-hydroxybenpur)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
- phenylenediamine, 2-mercaptobenzimidazole, phenyl-β-naphthylamine, N,N'-diphenyl-p-phenylenediamine, a condensation reaction product of diphenylamine and allyl ketone, preferably potassium iodide, 2-mercaptobenzimidazole, etc. be.

The antioxidant can be added to the polyamide during the polymerization process or once it is made into a chip and then added to the chip.

The content of antioxidant is 10 to 300 p as copper for copper salt.
pm, preferably 50-2oO1) pm% other antioxidants 0.01-1%, preferably 0.03-0.5
% range. The antioxidant is preferably used in combination with one or more of copper salts and other antioxidants.

The polyamide dried to a moisture content of 0.1 or less is spun using a melt spinning machine, preferably using an extruder type spinning machine.

The spinning take-off speed is such that the birefringence of the collected yarn is 25X10.
-, preferably less than 10XIO. The spinning conditions corresponding to the birefringence are determined by optimizing not only the spinning take-off speed but also many factors such as the nozzle hole diameter, the distance between the nozzle and the quench, the relative viscosity of the IJ, and the spinning temperature. If the birefringence of the spun drawn yarn is 25X10-'' or more, it will stably maintain cutting strength [DT is 10 P/d or more and become a strong yarn.

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 is, for example, melt-spinning nylon 66 with RV = 3.0 to obtain a birefringence of 5X10'' to 10XIO.
-" When stretching the drawn yarn continuously after spinning or after winding it once, between the undrawn yarn first supply roller and the undrawn yarn second supply roller maintained at 100°C or less, 1
．． It is preferable to give a preliminary stretching of 10 times or less, and then perform a first stage stretching of 4.0% or more of the total stretching ratio with the first stretching roller, and if necessary, with the undrawn yarn second supply roller. A high-temperature pressurized steam jet nozzle is provided between the first stretching roller and the nozzle temperature is set to 1200° C. or higher to jet high-temperature steam, and the stretching point is completely fixed near the high-temperature pressurized steam jet nozzle. Furthermore, when performing the second stage stretching, an FC ambient air temperature of 170 to 35 is provided between the first stretching roller and the second stretching roller.
In a 0°C slit heater (a heating device that has a slit as a thread running path and heats the thread while running it in a non-contact state through the slit: the ambient temperature refers to the temperature inside the slit) It is allowed to pass through so that the sound thread remains for 0.3 seconds or more, and then subjected to a second stretching roller. At that time, a temperature gradient was created in the slit heater,
It is preferable that the atmospheric temperature at the yarn inlet is 160° C. or higher, the exit atmospheric temperature is 13 to 350° C. or lower, and the yarn is allowed to pass through the yarn so that it can stay in the atmosphere of 170 to 350° C. for 0.3 seconds or more. In addition, after the completion of two-stage stretching, it can be carried out continuously without winding, or after winding once, 210
It is also possible to further improve the dimensional stability by performing a relaxing treatment of 10% or less at ~150°C. In order to obtain the high strength, low elongation yarn used in the present invention, the maximum draw ratio is 85%. The above is drawn at a high magnification, preferably 90% or more, so that the residual elongation is 8 to 20%, but it is basically determined by the stretching magnification of each sample and 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≧10 t/d (f) 20%≧DE≧8% ()) Is≧35 f/d (e) SHD≦15 14- The nylon 66 multifilament yarn obtained above is This is twisted in a conventional manner to form a raw cord.

Furthermore, hot stretching is performed following the dip liquid treatment to improve the adhesion to the raw cord or the whole rubber of the blind fabric woven from the raw cord.

The inventors of the present invention have thoroughly investigated the whole process from making raw cord to dip processing cord 17, and have found that it is possible to make the dip cord highly strong, have a low intermediate elongation, and a low shrinkage rate, compared to the conventional nylon 6-dip cord. The present inventor discovered that it is possible to achieve superior performance that cannot be achieved with cords.

That is, in the case of the high-strength, low-elongation nylon 66 fiber used in the present invention, the twist coefficient (TxfD) is usually less than 20.
00 to 2200 (for example, 47 for 840 d/2 twist
turn/], Ocm), the strong utilization rate of the raw cord decreases, but when the twist coefficient' is 1300 to 2000. Preferably, setting it in the range of 1,400 to 1,800 gives a very good tensile strength utilization rate, and by lowering the total hot stretch ratio in the dipping process to 0 to 5%, a dip cord with a low shrinkage rate and low intermediate elongation can be obtained. is 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 dipping process is set to 7% to 12 inches in order to increase the modulus of the cord. on the other hand,
Generally, when the hot stretch ratio in the dipping step is increased, the shrinkage rate of the dipped cord increases and the dimensional stability decreases.

Therefore, the nylon 66 dipped cord in this groove cannot satisfy both dimensional stability and high modulus.The feature of the present invention is that the conventional nylon 66 dipped cord is
6. By stretching the molecular chains more than in high strength yarns, high strength, high modulus, low elongation yarns have already been created, and after twisting, the modulus of the dipped cord is increased by hot stretching in the dipping process. In other words, since there is no need to lower the intermediate elongation, the load on the cord during the dipping process is reduced, resulting in a low shrinkage rate and low intermediate elongation ( High modulus) and high strength dip cords have all been achieved.

None of the conventional nylon 66 dipped cords had a breaking strength A of 8.5 f/d or more, and an intermediate elongation [B] and a dry heat shrinkage rate C satisfying the following formulas. (See Figure 1) (b) B ≦ 8.5% f→ 056%) C ≦ -2B+19 These dip cord characteristics have a twist coefficient of 2000 to 13.
00, more preferably in a low twist number region of 1800 to 1400, and a hot stretch ratio of O to 591+ in the dipping process.
This can only be achieved under low stretch conditions.

Reducing the number of twists has the advantage of increasing the twisting speed and reducing costs17-, but according to conventional knowledge, it has the disadvantage of decreasing fatigue resistance.

However, the dip cord of the present invention satisfies the formulas (a) to (b), so that even a low-twist cord has a fatigue-resistant sound higher than that of a conventional cord with a twist number. 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 refers to polyurethane resin, styrene-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, diene rubber, and the like.

Flat belts such as conveyor belts used in industrial machinery can be driven by having only one side pressed against a belt drive roller, or driven by having both sides of the belt pressed by nip rollers. It depends.

Therefore, depending on the purpose, one or both sides of the belt are coated with resin, or the belt is impregnated with a spray gas. Alternatively, the resin film may be stacked on the base fabric and bonded by heating and pressing.

18- As a result of the belt of the present invention being constructed as described in the claims, it has higher strength than conventional belts, has appropriate elongation suitable for the application, and has further durability. This belt has both abrasion resistance and 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.

Measuring method of relative viscosity〉 Prepare a sample solution by dissolving the sample in 96.3±0.1 weight reagent special grade concentrated sulfuric acid so that the polymer concentration is 10μ/-, and heat at 20℃±0. Ice falling seconds at a temperature of 05°C 6
Measure the solution relative viscosity using an Osttwald viscometer at ~7 seconds. During the measurement, the same viscosity meter was used, and from the ratio of the falling time T, (seconds) of sulfuric acid 20-, which is the same as when all sample solutions were prepared, and the falling time T, (seconds) of sample solution 20-,
The relative viscosity RV is calculated using the following formula.

RV=T, /T.

Measuring method of birefringence (Δn) A Nikon polarizing microscope POH model Utsu Co., Ltd. Perec convensator was used, and a spectral light source starter (Toshiba 5LS-3-B model) was used as a light source (Na light source). 5~
A sample cut at an angle of 45 degrees to the fiber axis of Bwa length is placed on a glass slide with the cut surface facing upward. Place the sample slide glass on the fully rotating stage, adjust the rotating stage so that the sample is 45 degrees square with the polarizer,
After fully inserting the analyzer and making it a dark field, set the compensator to 30 and count all the number of stripes (n pieces).Turn the -1 compensator clockwise and set the compensator I) at the point where the sample first becomes darkest. Scale a.

After turning the compensator in the left-hand direction and measuring the scale bi of the compensator at the point where the sample first becomes darkest (read up to 1/10 scale), return the compensator to 30 and remove the analyzer. Measure the diameter d of the sample and use the following formula to calculate the birefringence index (Δn) Th
Calculate (average value of 20 measurements).

Δn=r/d (F=nλ. 1ε) λ. =589.3mμ ε: C/100 in the manual of the compensator from Rait Co.
00 and i 1: (a-b) (: Difference in compensator reading) <Method for measuring strength and elongation characteristics of fibers and cords> JIS-L10
According to the definition of 17. Take the whole sample into a duck shape and heat it at 20℃, 65℃.
After being left for 24 hours in a temperature and humidity controlled room at %RH, it was tested using a Tensilon UTM-4L tensile tester (manufactured by Toyo Baldwin) with a test length of 20 stripes and a tensile speed of 20 (7) 7.
Measured in minutes.

<Formula for calculating twist coefficient> Twist coefficient plus number of twists x (denier) number of 100 twists: turn/10an <Method for measuring disk fatigue> Created by embedding a dip cord and vulcanizing using a normal disk fatigue tester. Set the test piece and set the compression ratio to 1.
After applying forced fatigue by rotating at a speed of 250 rpm for 48 hours under an elongation ratio of 2.5% and an elongation ratio of 6.3%, the dipped cord was removed from the rubber and its residual strength was measured.

21- <Method for measuring intermediate elongation> According to the definition of JIS-L1017. Measure the total elongation rate under a constant load W (groaning). The elongation measurement conditions are based on the measurement conditions for strength and elongation properties. The constant load W is defined by the following formula.

W = 4.5 x 1"d" d: Sample denier, dl: Standard denier, which is 840 denier for raw yarn and 1680 denier for cord.

Measuring method of dry heat shrinkage SHD〉 Take the entire sample into a duck shape, leave it in a temperature and humidity controlled room at 20°C and 65% RH for more than 24 hours, and then apply a load equivalent to 0.11/d of the sample. A sample with length n7'5 and length t, measured by applying the same load, was left in an oven at 150°C for 30 minutes under no tension, then taken out of the oven and left in the temperature/humidity control room for 4 hours, and then subjected to the above load again. It was calculated from the measured length t□ by the following formula.

22-Production Example> Using nylon 66 with the relative viscosity shown in Table 1 as a raw material, spinning was carried out under the conditions shown in the same table, and the birefringence Δn(2
An undrawn yarn with a relative viscosity (measured after standing for 24 hours at 0° C. and 65% RH) 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 adivamide fiber for tire cords 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.

23 - 1st Table 24 - 2nd Table 25 - 3rd Table
0 cm, and 840. It is expressed as a d/2 ply two-stranded cord.

On the raw code obtained in this way, 1/zorcin bomb formalin
It was immersed in a nylon 6 dip solution consisting of a latex solution, and then dried with hot air at 120° C. for 2 minutes under a 1.5% stretch.

Subsequently, the material was introduced into a hot stretch zone and subjected to 1st, 3rd, and 7% hot stretching in heated air at 26-200°C, and further heat-treated for 36 seconds in heated air at 200°C for a fixed length, followed by dipping. produced the code.

The properties of the raw cord and dipped cord according to this production example were as shown in Table 4.

The dipped cord obtained in the present invention has significantly improved strength compared to the dipped cord obtained in the comparative example, has low intermediate elongation, and has a small dry heat shrinkage rate, which is a measure of dimensional stability, and has a low twist region. It also has excellent fatigue resistance.

27- Next, the dipped cords obtained in the ratio 7 of Invention 1 and Comparative Example 1 in Table 4 were used for the warp yarns and all the weft yarns of the dipped cord made of high-strength polyester fibers to weave into a double twill weave structure, Cover both sides with rubber and create a belt tracker.
Their strength and expansion properties 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 5

[Brief explanation of drawings]

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

Claims (1)

[Claims] 1. The repeating structural unit of hexamethylene adipamide is 9
Polyhexamethylene having a high polymerization degree of 5 molti or more and 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 salts. A polyhexamethylene adipamide-based dip cord made of adipamide fibers and having a twist coefficient of 2000 to 1300 and a top twist and a bottom twist, to which a dip liquid is attached to improve adhesion to rubber. , using polyhexamethylene adipamide dip cord, which has the following characteristics at the same time and has high strength and high modulus, as well as significantly improved dimensional stability and fatigue resistance, as the base fabric.
Rubber belts are high-strength belts made of flexible resin coated on one or both sides. (a) Breaking strength of dip cord A≧s, sf/d'
(b) Intermediate elongation of dip cord [B≦8.5chie now Dry heat shrinkage rate of dip cord to C50chi] C≦-2B
+19 2. In claim 1, the breaking strength of the dip cord is 9. A high-strength belt using a polyhexamethylene adipamide dip cord, characterized in that the dry heat shrinkage rate of the dip cord is 5 inches or less. 3. A high-strength belt using polyhexamethylene azino (mido-based dip cord), which is characterized in that the twist coefficient of the dip cord is 1,800 to 1,400 in claim 1 or 2. , rubber or flexible resin is polyurethane resin,
Claim 1 is one or a combination of two or more selected from the group consisting of styrene-butadiene rubber, chloroprene rubber, ethylene propylene rubber, and diene rubber.
The high-strength belt according to any one of items 1 to 3.