JPS63285347A - Belt - Google Patents

Abstract

PURPOSE:To improve modulus of elasticity by using polyester fiber, as foundation, whose limited viscosity and initial tensile modulus of elasticity are specific and which contains specific weight of polyester/polyether block copolymer. CONSTITUTION:Foundation is formed by using twisting consisting of polyestor fiber made of ethylene terephthalate polyester containing 0.2-15 weight % of polyester/polyether block copolymer, while said polyester fiber having a limited viscosity IV more than 0.6 and an initial tensile modulus of elasticity is more than 160g/d. And rubber of flexible resin is spread on one side or both sides of the foundation to form a belt. Meanwhile, polyester fiber is preferable to have characteristics such as birefringence factor n more than 180X10<-3>, specific gravity SG more than 1.390 and dry heat shrinking percentage SHD160 less than 6%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to flat belts such as conveyor belts used in industrial machines, V-belts, and belts such as automobile seat belts.

Specifically, the present invention has an intrinsic viscosity IV of 0.6 or more, an initial tensile modulus IS of 160 g/d or more, and a polyester/polyether block copolymer of 0.2 to 15
The present invention relates to a belt made of a base fabric made of twisted threads of ethylene terephthalate polyester fibers containing ethylene terephthalate fibers in an amount of % by weight, and coated on one or both sides with rubber or flexible resin.

[Conventional technology]

Traditionally, belts of this type have been 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 cannot be said that it is sufficient in terms of strength, elastic modulus, elongation, chemical resistance, etc.

[Problem that the invention seeks to solve]

The properties required for flat belts, V-belts, etc. are high strength, high modulus of elasticity, low elongation, and chemical resistance.

It goes without saying that high strength and high elastic modulus are required, and at the same time, moderate and low elongation is also required. If the elongation is too high, the bell H 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. 75, a twisted yarn consisting of fibers mainly composed of polyparaphenylene terephthalamide and fibers mainly composed of polymetaphenylene isophthalamide is used for the warp,
Belts made of fibers mainly composed of polymetaphenylene isophthalamide have been proposed, but there are problems with abrasion resistance when used for a long period of time, and the belt wears out at the contact surface between the belt and the belt drive unit. However, there is a disadvantage that 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. In addition, the belts used in industrial machinery are used for a wide variety of chemicals and chemicals in the industrial field.
Most commonly used chemicals such as acids such as sulfuric acid or alkalis such as caustic soda may cause the belt to get wet or become wet. It has also been found that the wear resistance rapidly decreases due to corrosion due to corrosion caused by the like, and that the wear resistance also decreases markedly.

Under these current circumstances, the present inventors have developed a belt structure that has high strength, high elastic modulus, and appropriate elongation, is resistant to corrosion by acids and alkalis, and has excellent abrasion resistance. As a result of intensive research, the present invention was arrived at.

[Means for solving problems]

That is, the gist of the present invention is a polyester fiber made of ethylene terephthalate polyester containing 0.2 to 15% by weight of a polyester/polyether block copolymer and having the following characteristics (a) and (b). This belt is made of a base fabric made of twisted yarn and coated with rubber or flexible resin on one or both sides.

(a) Intrinsic viscosity IV is 0.6 or more (b) Initial tensile modulus IS is 160 g/d or more The polyester fiber used in the present invention preferably has the above (i)
In addition to and (b), the following (c),) and (
It has the characteristics of (e).

(c) Birefringence △n is 180X10 -3 or more (d)
Specific gravity SG is 1.390 or more (e) Dry heat shrinkage rate SHD. Further, the polyester fiber used in the present invention more preferably has the following properties (f), (g), and (b) in addition to the above-mentioned properties.

(f) Tensile elongation is 3 to 10% (g) Tensile strength is 897 d or more (g) Peak temperature Tα of mechanical temperature dispersion tan δ is 140
~155°C The polyester fibers constituting the belt of the present invention will be explained in more detail below.

The polyester fibers constituting the belt of the present invention are (a)
Intrinsic viscosity IV is 0.6 or more, (b) initial tensile modulus IS
It is an essential requirement that the modulus is at least 160 g/d (which is significantly higher than conventional high modulus polyether lv fibers, which are at most 120 g/d).

When the intrinsic viscosity IV is less than 0.6, the strength of the belt decreases, causing problems in durability. In addition, the initial elastic modulus IS is 16
If it is less than 0.9/d, the effects of using the highly elastic base fabric, which are the characteristics of the belt of the present invention, such as being less likely to sag and being able to easily apply tension to the belt, cannot be fully exhibited.

The polyester fibers constituting the belt of the present invention are as described above (
In addition to the characteristics (a) and (b), (c) the birefringence Δn is 180×10-” or more (preferably 190×
10- or more), 2) Specific gravity SG is 1.390 or more, (E)
It is preferable that the dry heat shrinkage rate SHD is 6% or less. Birefringence △n is 180X
If it is less than 10", the initial resistance IS will be reduced to 160 g/
d-3 or higher (d) becomes mature, making it impossible to fully demonstrate the characteristics of using a high-elastic base fabric when used as a belt.If the specific gravity SG is less than 1.390, the initial elastic modulus is also If the IS is 160.9/d-3 or more (2), it will become mellow, so when it is made into a belt, it will not be able to fully demonstrate the characteristics of using a high elastic base fabric.In addition, the dry heat shrinkage rate SHD, If , exceeds 6%, problems will arise in the dimensional stability of the belt, and the belt will be more likely to sag.

In addition to the above-mentioned properties, the polyester fibers constituting the base of the present invention also have (f) a tensile elongation of 3 to 10%, (g) a tensile strength of 897d or more, ( g) Peak temperature Tα of mechanical temperature dispersion tanδ is 140 to 155°C
It is preferable to have the following characteristics (lower value than ordinary high-strength polyester fibers, which have a retraction temperature of around 160° C.). If the tensile elongation exceeds 10%, sagging tends to occur over time when the belt is made, while if it is less than 3%, it becomes difficult to apply sufficient tension to the belt. Moreover, if the tensile strength is less than 5g7a, there will be a problem in durability when used as a belt. When the peak temperature Tα of mechanical dispersion tan δ exceeds 155° C., heat generation increases, fatigue resistance as a belt decreases, and cracks are likely to occur during long-term use. On the other hand, this peak temperature is 140
If the temperature is less than 0.degree. C., it will be difficult to make the initial elastic modulus IS 16097d or more, and it will be difficult to fully utilize the feature of the present invention, which is the use of a highly elastic base fabric.

In the present invention, the above characteristics can be achieved by forming fibers using ethylene terephthalate polyester having an intrinsic viscosity of 0.6 or more and containing 0.2 to 15% by weight of a polyester-polyether block copolymer. is effectively demonstrated. That is, the specified amount of polyester
The polyether block copolymer exhibits a plasticizer-like effect in polyester fibers, improves high-speed spinnability and drawability, and exhibits remarkable effects such as high strength, high modulus, and improved fatigue resistance.

The ethylene terephthalate polyester used in the present invention is a polyester consisting of a dibasic acid mainly consisting of terephthalic acid and ethylene glycol, particularly polyethylene terephthalate, and 10 moles of a known third component is added to polyethylene terephthalate. % or less, preferably 5 mol% or less, copolymerized products can also be used.

Here, the main third components include isophthalic acid, sulfoisophthalic acid, 7-divic acid, neopentyl glycol, pentaerythritol, glycerin, polyethylene glycol, polyether of polyethylene glycol in alcohol, but other known components are optional. Can be used for

In addition, as a polyester polyether block copolymer, 60 polytetramethylene terephthalate units are used.
It is a block copolymer in which the hard segment is a polyester unit containing 80 mol% or more of polytetramethylene ether glycol units, preferably 80 mol% or more, and the soft segment is a polyether unit containing 80 mol% or more of polytetramethylene ether glycol units. As the polyester unit, in addition to the polytetramethylene terephthalate unit, one or more types of polymethylene terephthalate units, polypropylene terephthalate units, polyethylene isophthalate units, etc. may be copolymerized in a proportion of up to 20 hols. In addition to polytetramethylene ether glycol units, polyether units include up to 20 mol% of polyethylene ether glycol units, polypropylene ether glycol units, polyhexamethylene ether glycol units, etc.
One species or two or more species may be copolymerized. In addition, the copolymerization components of the hard segment and the soft segment are not limited to those exemplified above, and in particular, isophthalic acid, dimer acid, and 3,5-di(carbomethoxy)benzenesulfonic acid metal salts are copolymerized. When a copolymerized component is used as a component, it is practically useful in terms of cost reduction or dyeability improvement. Among these, the most preferred is a polyester/polyether block copolymer having polytetramethylene terephthalate as a hard segment and polytetramethylene ether glycol as a soft segment. The copolymerization ratio (J&) of the aromatic polyester as a hard segment and the polyalkylene ether glycol as a soft segment is preferably 65:35 to 95:5, more preferably 75:25 to 90:10. . That is, it is usually used as a thermoplastic elastomer for chemical products, and is characterized by a large amount of hard segments compared to the copolymerization ratio. In addition, the number average molecular weight of the polyalkylene ether glycol is 500 to 4,000. is suitable, and more preferably 1000 to 2000.

A preferable method for producing the novel ethylene terephthalate polyester fiber constituting the belt of the present invention will be described in more detail below: Intrinsic viscosity [IV O, from the above-mentioned main component polyester, polytetramethylene glycol, and polybutylene terephthalate. After vacuum drying each copolymer, they are blended in the form of chips. The weight fraction of the polyether/ester copolymer to be blended is 0.2 to 15% by weight, preferably 0.2 to 10% by weight.
Weight%. For polyesters with an IV of less than 0.6,
The desired strength and initial elastic modulus cannot be obtained. In addition, when the weight fraction of the block copolymer is less than 0.2% by weight, it exhibits the same tensile strength and initial elastic modulus as ethylene terephthalate that does not contain the polyether-ester copolymer, and has the same tensile strength and initial elastic modulus as the conventional one. There will be no big difference.

On the other hand, if this weight fraction exceeds 15%, the spinning state becomes unstable, the unevenness in the length direction of the yarn becomes large, and both the strength and elastic modulus decrease.

The thus blended chips are melt extruded at a temperature at least 20°C higher than the melting point of the polyester. The melt extrusion method is not particularly limited, but extruder type extruder, piston type extruder, 2
A axial kneading type extruder or the like is used. The conditions for extruding through the nozzle orifice from the extruder are a shear rate P of 10
The shear rate is preferably less than "se♂".The shear rate is calculated using the following formula.

When the temperature exceeds 10'5 ec-', melt fracture tends to occur, making it difficult to improve physical properties.

The thus extruded polyester yarn is cooled and solidified, and after applying an appropriate amount of oil, the yarn is taken off so that the birefringence Δn is 0.002 to 0.060. △n is 0
．． When the temperature exceeds 060, the effect of improving stretchability by subsequent stretching at a temperature of less than 90°C becomes small;
As a result, it becomes difficult to achieve high physical properties, while △n
When the ratio is less than 0.002, the spinning state becomes extremely unstable and it becomes difficult to suppress unevenness in the length direction of the yarn. △n of the polyester drawn thread is 20.002 to 0.
015 is most preferable.

The undrawn polyester fiber thus obtained was
Stretching is carried out by a factor of (100+NE)/100 times or more at a temperature below °C. Here, NE refers to the natural draw ratio of the undrawn yarn. If the stretching temperature is 90° C. or higher, crystallization will proceed before stretching and stretchability will be inhibited.

Following the low-temperature stretching, stretching is performed at a temperature range of 150 to 250°C. Multi-stage stretching is preferred for this high-temperature stretching;
It is preferable to carry out the stretching at a temperature range of 250°C to 250°C.

Polyester fibers with the above-mentioned properties are thus obtained.

Such polyesters can be blended with matting agents, pigments, light stabilizers, heat stabilizers, antioxidants, antistatic agents, dyeability improvers, adhesion improvers, etc. as necessary. All materials can be used except those that have a serious adverse effect on the characteristics of the present invention.

The base fabric in the present invention may be manufactured by any of the commonly used methods such as plain weave and stacked fibers, but plain weave is most preferred.

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, resin coating is done by coating, impregnating, or spraying resin on one or both sides of the material, depending on the purpose.

Alternatively, the resin film may be superimposed on the base fabric and bonded by heating and pressing.

In any case, the feature of the present invention lies in the specification of the polyester fibers constituting the belt, and the manufacture of the belt using the same can be carried out by a known method.

As a result of the belt of the present invention being constructed as described in the claims, it has higher strength and higher elastic modulus than conventional belts, and can also have an appropriate elongation suitable for the purpose. Furthermore, the belt has both wear 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.

<Method for Measuring Intrinsic Viscosity> Measurement is performed in a mixed solvent consisting of 75% by weight of p-chlorophenol and 25% by weight of tetrachloroethane.

The polymer is dissolved in the solvent at room temperature and the viscosity measurements are carried out in an Ostwaldfenske capillary viscometer at 30°C.

Intrinsic viscosity is the limit value at which the natural logarithm of the ratio of solution viscosity to solvent viscosity divided by the concentration of the polymer solution in grams of polymer per 100 M of solution approaches zero concentration.

<Method for measuring birefringence (△n)> A Nikon polarizing microscope POH type Ui-sha Pellec convenser was used, and a spectral light source activation device (Toshiba SLS-3-B type) was used as the light source (Na light source). . 5
A sample cut at an angle of 45° to the fiber axis with a length of ~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 oriented at 45 degrees to the polarizer, insert the analyzer 1 to set the dark field, and then set the compensator to 30°. count the number of stripes (n pieces). Turn the compensator clockwise to measure the point at which the sample first becomes darkest (a); turn the compensator counterclockwise to measure the point at which the sample first becomes darkest (compensator scale b). (read up to 1/10 scale), return the compensator to 30, remove the analyzer, measure the diameter d of the sample, and calculate the birefringence (△n) based on the formula below (20 measurements) average value).

Δn=r/d F nylon tarpsion,=nλo+4λ. =589.
3mμ ε: C/100 of compensator manual of 249 companies
1 determined from 00 and i = (a-b) (: difference in compensator reading) <Mechanical temperature dispersion> Using Rheovibron manufactured by Toyo Sokki Co., Ltd., initial yarn length 4
m, heating rate 2℃/min, sine frequency during measurement 110)1
The temperature (Tα) at which the loss tangent tanδ=E″/E′ becomes maximum is determined by measuring under the conditions of z.

However, in the above formula, E' is the storage modulus (dyne/c!f
t), E' is the loss modulus (dyne/ff1).

[Details? (11 is Memoirs of the Fa
Engineering-neering Kyu
Shu University, vol, 23. 4
1 (1963)] The complex modulus of elasticity E is calculated by the following formula.

However, A: Coefficient due to the amplitude factor (Ampl: Factor) at the time of tanδ measurement (see Table 1 D: Dynamic Force Dial value L:
Sample length (clIL) S: Sample cross-sectional area (c!l) Table 1 Storage modulus E' is E"" l E l cos δ loss modulus E' is E' = l E I sin δ - (6
) is calculated.

<Dry heat shrinkage rate> Measured at 160°C according to JIS-L1073 (1977).

<Specific Gravity> Create a density gradient tube made of n-hebutane and carbon tetrachloride, place a sufficiently defoamed sample into the density gradient tube whose temperature is controlled to 30℃±0.1℃, and leave it for 5 hours. The sample position in the subsequent density gradient tube was read on the scale of the density gradient tube, and the value was converted into a specific gravity value from the density gradient tube scale to specific gravity calibration graph using a standard glass float, and measured at n=4. As a general rule, read specific gravity values to four decimal places.

<Method for measuring fiber fineness> In a test room under standard conditions (temperature 20 ± 2°C, relative humidity 65 ± 2%), an autobibro type fineness measuring instrument DENIER COMPUTER DC-IB model manufactured by Saatchi ■ was used. The fineness (denier, d) of the single fibers was measured.

However, the fiber measurement sample length was 90 cIrL.

<Delicate strength measurement method> Tensile strength of fibers) is JIS-L-1013
(1981), the tensile strength of single fibers was measured in a test room under standard conditions using a constant speed extension type universal tensile testing machine TENSILON (ITM-Ill) manufactured by Toyo Baldwin ■. .

However, the measurement conditions were as follows: a 9f tension type load cell was used, gripping interval was 1 ocrrL, tension speed was 1°/min (extension speed of 100% of gripping interval per minute), and recording paper feeding speed was 50crrL/min. The sample was pulled and the load (gf) when the sample was cut was measured, and the tensile strength (gf/d) was calculated using the following formula and was defined as the strength (P/d).

<Measurement method of initial tensile modulus of fiber> The initial tensile resistance (initial tensile modulus) of fiber is determined according to JIS-
The test was conducted using the same method as the above method for measuring fiber strength according to 7.5.1 of L-1013 (1981), and a load-elongation curve was drawn on recording paper. From this figure, JIS-L-
The initial tensile resistance (gf/d) was calculated using the initial tensile resistance calculation formula described in 7.10 of 1013 (1981), and was defined as the initial tensile modulus (P/d).

[For production]

The polyester fibers constituting the belt of the present invention have excellent properties such as high strength and high elastic modulus.By adding an appropriate amount of polyester/polyether copolymer to ethylene terephthalate polyester, the copolymer is This is thought to be due to the fact that the coalescence plays the role of a plasticizer and helps stretch the polyester molecular chain to a high degree. It is presumed that when the fraction of the copolymer increases, a reaction with the polyester component occurs, and the polyester no longer has the properties of a polyester, and the property of high tensile modulus is lost.

In the present invention, the most important point in achieving a highly elongated molecular chain arrangement is to add a polyester/polyether copolymer to ethylene terephthalate polyester, perform melt spinning, and perform a stretching process under appropriate conditions. It is presumed that this is due to the high orientation.

〔Example〕

Examples are shown below, but the present invention is of course not limited to these examples.

The polymers used in the examples were as follows. That is, the ethylene terephthalate-based polyester is used as a tetramethylene glycol and polybutylene terephthalate copolymer using polyester chips for tire cords with IV = 1.0, and the molar fraction of polytetramethylene glycol and polybutylene terephthalate is as follows: A ratio of 25.5 to 4.5 was used.

Each polymer was vacuum dried under the following conditions.
1 After drying, the copolymer of ethylene terephthalate polyester and polytetramethylene glycol was mixed with an Mlk ratio of 98.
: Blend in the form of chips in Step 2, and use an extruder type spinning machine at a spinning temperature of 305°C and a single hole discharge rate of 1.5 l/
Melt extrusion was performed through a nozzle with a hole diameter of 0.4 nφ under conditions of
It was wound up at 600 m/+in. Δn=0.0578. The NE of the undrawn yarn was 14%. Further, the undrawn yarn was stretched 1.14 times at room temperature (stretching speed 21.1 m/min), and then at 160°C at a stretching ratio of 1.66 times.
Two stages of stretching were carried out at 245° C. and a stretching ratio of 1.08 times (total of three stages of stretching). The obtained drawn yarn had fiber physical properties of 30.6 denier and tensile strength of 9.38 y/d.

The initial elastic modulus was 166.9 P/d.

Example 2 After drying, a copolymer of ethylene terephthalate polyester and polytetramethylene glycol was mixed in a weight ratio of 98:
Blended in the form of chips in Step 2, and spun using an extruder type spinning machine at a spinning temperature of 305°C and single hole discharge f! 1.5 Ji
Melt extrusion is carried out through a nozzle with a hole diameter of 0.4 mm under conditions of 1/min, and after cooling and solidifying with cooling air of 0.35 rrL/sec, approximately 1% oil agent is applied to the yarn and the spinning speed is reduced. It was wound up at 4500 m/min. △n=0.09
It was 76. The NE of the undrawn yarn was 4%. Further, the undrawn yarn was stretched 1.04 times at room temperature (stretching speed 277 m/min), and then at 160°C at a stretching ratio of 1.51.
The film was stretched in two stages at a stretching ratio of 1.07 times at 245° C. (three stages in total). The fiber physical properties of the obtained drawn yarn were 27.8 denier, tensile strength 8.38 P/ct1, initial elastic modulus 1
It was 86.15 L/d.

Comparative Example 1 Dry ethylene terephthalate polyester was spun using an extruder-type spinning machine at a spinning temperature of 305°C and a single-hole discharge rate of 1.59/min with a pore diameter of 0. The yarn was melt-extruded through a nozzle with a diameter of 0.35 m/sec, cooled and solidified with cooling air at a rate of 0.35 m/sec, and then an oil agent of about 1% was applied to the yarn and wound at a spinning speed of 2500 rrL/1lIIin. △
n=0.0404.

The NE of the undrawn yarn was 15%. Furthermore, the undrawn yarn was stretched 1.15 times at room temperature (stretching speed 22.2
m/min), then at 160°C, stretching ratio 1.52 times, 245°C
The film was stretched in two stages (total of three stages) at a stretching ratio of 1.14 times.

The fiber physical properties of the obtained drawn yarn were 38.3 denier, tensile strength 9.81 P/d, and initial elastic modulus 154.3 P/d.

Comparative Example 2 As Comparative Example 2, a commercially available high-strength grade polyester fiber for tire cord was used.

Table 2 shows the fiber quality and related data in these Examples and Comparative Examples.

Table 2 Qin Qin unstretched physical properties 1000 denier and 1500 denier multifilament yarns made of the polyethylene terephthalate fibers of Example 2 and Comparative Examples 1 and 2 were produced and woven into a double twill structure under the conditions shown in Table 3. A belt was then impregnated with urethane resin containing silicone resin as a smoothing agent. As for the physical properties of the product, as shown in Table 3, the product of the present invention has a higher elastic modulus and higher strength than the conventional product.

〔Effect of the invention〕

The belt of the present invention is suitably used for flat belts and V-belts such as conveyor pairs A/) used in industrial machines, automobile seat belts, and the like.

This belt has significantly higher elastic modulus and improved fatigue resistance than conventional products.

Claims (1)

[Claims] (1) In a belt in which one or both sides of a base fabric are coated with rubber or flexible resin, the base fabric is made of twisted yarn using polyester fibers, and the polyester fibers are polyester/polyether block copolymers. 0.2～
A belt comprising ethylene terephthalate polyester fiber containing 15% by weight and having the following characteristics (a) and (b). (a) Intrinsic viscosity IV is 0.6 or more (b) Initial tensile modulus IS is 160 g/d or more (2) Polyester fibers are further below (c), (d) and (e)
A belt according to claim 1 having the following characteristics. (c) Birefringence △n is 180×10^-^3 or more (d)
Specific gravity SG is 1.390 or more (e) Dry heat shrinkage rate SHD_1_■_■ is 6% or less (3)
Polyester fibers are further added to the following (F), (G) and (H).
The belt according to claim 1 or 2, having the following characteristics. (F) Tensile elongation is 3 to 10% (G) Tensile strength is 8 g/d or more (H) Peak temperature Tα of mechanical temperature dispersion tan δ is 140
~155°C (4) 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. Belt according to range 1, 2 or 3.