JP2010126838A - Polyphenylene sulfide monofilament, method for producing the same, and industrial fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyphenylene sulfide monofilament having high dimensional stability and high abrasion resistance and capable of giving industrial fabrics with high surface smoothness, to provide a method for producing the same, and to provided such an industrial fabric of high surface smoothness where the polyphenylene sulfide monofilaments are used in at least part of warps and/or wefts thereof. <P>SOLUTION: The polyphenylene sulfide monofilament meets the following expression (a): [B-A]/fineness (cN/dtex)≤0.030 (wherein, A is the shrinkage stress (cN) measured in accordance with the specifications of ASTM 5591; and B is the shrinkage stress (cN) measured after cooled to 25°C), after measuring the A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polyphenylene sulfide monofilament, a method for producing the same, and an industrial fabric. More specifically, a polyphenylene sulfide monofilament capable of providing an industrial fabric having high dimensional stability and excellent wear resistance and excellent surface smoothness, a method for producing the same, and a surface smoothness using the polyphenylene sulfide monofilament The present invention relates to industrial fabrics such as fabrics for conveyor belts excellent in properties, dryer canvas fabrics for papermaking, filter fabrics, net conveyors for thermal bonding nonwoven fabric bonding processes, and papermaking wires.

  In industrial textile applications such as conveyor belt fabrics, papermaking dryer canvas fabrics, filter fabrics, net bonds for thermal bond method nonwoven fabric bonding processes and papermaking wires, these fabrics can be used in high-temperature atmospheres of, for example, 130 ° C or higher. Because it is exposed to chemical environments such as high concentrations of acid and alkali, the textile material fiber has high heat resistance, high knot strength and high bending resistance, as well as heat resistance and chemical resistance. There is a strong demand.

  In general, fibers represented by monofilaments made of polyester, such as polyethylene terephthalate, have excellent mechanical properties, heat resistance, etc., so that they have conventionally been used for various industrial parts, clothing and industrial fiber materials, various fabrics, etc. However, when the polyester monofilament is used as a constituent material of a paper-making dryer canvas, the polyester monofilament is degraded by hydrolysis during use. It had the disadvantage of causing a reduction in strength.

  In contrast, monofilaments made of polyphenylene sulfide (hereinafter referred to as PPS) fibers are excellent in heat resistance and chemical resistance, can exhibit high durability for a long time even under high temperature and high humidity conditions, and can be melt-molded. Therefore, proposals have been made to apply PPS monofilaments to paper making dryer canvases (see, for example, Patent Document 1), and many proposals have been made regarding techniques for producing PPS fibers and improving the fibers. Has been made.

  For example, an undrawn yarn obtained by melt spinning PPS is drawn 2 to 7 times at 80 to 260 ° C. and then taken up in a dry heat atmosphere of 285 to 385 ° C. at a draw ratio of 0.8 to 1.35 times. To obtain a PPS fiber having a tensile strength of 3.5 g / d or more and a knot strength of 2.5 g / d or more and improved bending wear and bending fatigue characteristics (for example, , See Patent Document 2).

  Further, by making the tensile strength 3.5 cN / dtex or more, the tensile elongation 50 to 80%, the 160 ° C. dry heat shrinkage 2% or less, and the hot water shrinkage 1% or less, PPS short fibers (see, for example, Patent Document 3) with improved mechanical durability and dimensional stability have been proposed.

  Furthermore, the tensile strength is 3.5 g / d or more, the knot strength is 2 g / d or more, the hook strength is 3.5 g / d or more, and the number of reciprocating frictions until cutting in the bending wear test is 3,000 times or more, and There has been proposed a polyphenylene sulfide fiber (see, for example, Patent Document 4) that has a number of reciprocal bendings of 150 or more until it is cut in a bending fatigue test and is excellent in mechanical strength, bending wear resistance, and bending fatigue resistance. .

  In addition, as a result of studying the same technique by the present inventors, a PPS monofilament obtained by spinning and stretching PPS having a melt flow rate of 20 to 120 g / 10 min, and dry heat shrinkage at 200 ° C. measured in a free state. The absolute value ΔSd of the difference between the rate (Sd200) and the dry heat shrinkage rate (Sd140) measured at 140 ° C. is 3.0% or less, (Sd200) is 15 to 32%, and the strength is 3.5 g / PPS monofilaments having performances suitable for paper-making spiral canvases having the characteristics of d or more, a method for producing this PPS monofilament (see, for example, Patent Document 5), and 85 mol% or more of structural units are p-phenylene sulfide units Polyphenylene sulfide comprising a polyphenylene sulfide having a melt flow rate of 150 or less The textile, dry heat shrinkage rate of 140 ° C. as measured in the free state (Sd140), also 200 ° C. dry heat shrinkage (SD200) the absolute value of the difference between ΔSd 3.0% or more, JIS. A polyphenylene sulfide fiber (see, for example, Patent Document 6) having a characteristic that the number of reciprocating frictions at the time of breaking in a bending wear characteristic test measured according to the regulations of L1095 is 7000 times or more has already been proposed.

  However, since the raw material of PPS monofilament is higher than that of polyester monofilament, when it is used on the entire surface of a fabric having a total length of several hundred meters, such as a papermaking fabric, the cost becomes extremely high. Therefore, as a material for papermaking fabrics, inexpensive polyester monofilaments are the mainstream, and polyester monofilaments having hydrolysis resistance specially examined for heat stabilizers are often used.

  Under such circumstances, PPS monofilaments are used only in parts that require particularly high heat resistance in woven fabrics, or are used in combination with polyester monofilaments, plain weaves and other transport belts having a low woven density per unit area. It is currently used as a fabric for fabrics, a fabric for filters, a reinforcing member for ears of fabrics, and the like.

  However, in recent years, there has been a problem that wrinkles are generated on the surface of the fabric immediately after the fabric woven using a part of the PPS monofilament is heat-set and taken out in a room temperature atmosphere. When wrinkles occur on the surface of the fabric, the surface smoothness is lost. For example, when used as an industrial fabric such as a dryer canvas, the paper quality is deteriorated.

  Such a phenomenon has not been studied in the above-described conventional technology for improving the characteristics of PPS fibers, and even if weaving using the modified PPS fibers obtained there, The problem that it was difficult to obtain an industrial fabric excellent in smoothness remained.

Therefore, PPS monofilament that has excellent heat resistance and chemical resistance, and can exhibit high durability for a long time even under high temperature and high humidity conditions, has high dimensional stability and wear resistance that does not cause wrinkles on the surface. It can be said that quality improvement for realizing excellent surface smoothness in the field of industrial fabrics was a major issue.
JP-A-49-54617 JP-A-4-222217 JP 2003-221731 A Japanese Patent No. 2878470 Japanese Patent Laid-Open No. 5-195318 JP 2004-292984 A

  The present invention has been achieved as a result of studying the solution of the problems in the prior art described above as an issue.

  Accordingly, an object of the present invention is to provide a polyphenylene sulfide monofilament capable of providing an industrial fabric having high dimensional stability and excellent wear resistance, and excellent surface smoothness, a method for producing the same, and a warp containing the polyphenylene sulfide monofilament. And / or industrial use such as fabrics for conveyor belts with excellent surface smoothness used for at least part of wefts, dryer canvas fabrics for papermaking, fabrics for filters, net conveyors for thermal bonding non-woven fabric bonding processes, papermaking wires, etc. It is to provide a woven fabric.

  As a result of diligent studies to solve the above-mentioned problems, the present inventors have improved heat shrinkage stress characteristics, thereby providing high dimensional stability and excellent wear resistance. This polyphenylene sulfide monofilament is used as warp and / or Alternatively, the present inventors have found that excellent surface smoothness can be realized when used for at least a part of the weft to make an industrial fabric, and have reached the present invention.

That is, in the present invention, when the contraction stress (cN) measured according to ASTM 5591 is A, A is measured, and the contraction stress (cN) measured after cooling to 25 ° C. is B, the following (a) A polyphenylene sulfide monofilament characterized by satisfying the formula is provided.
[BA] / Fineness (cN / dtex) ≦ 0.030 (a)

In the polyphenylene sulfide monofilament of the present invention,
The monofilament has a dry heat shrinkage at 180 ° C. of 8.0% or less, and the monofilament has a JIS. The number of reciprocating frictions at the time of fracture in the bending wear characteristic test measured in accordance with the regulations of L1095 is 7000 times or more;
However, it is mentioned as a preferable condition, and by satisfying this condition, a higher dimensional stability can be realized, and an industrial fabric having better surface smoothness can be provided.

  In addition, the method for producing the polyphenylene sulfide monofilament of the present invention having the above-described characteristics is obtained by subjecting the polyphenylene sulfide to melt spinning and then performing two-stage drawing and heat setting. It is characterized in that the set temperature is 200 ° C. or lower and the heat set magnification is 0.90 to 1.00.

  Furthermore, the woven fabric of the present invention is characterized by using the polyphenylene sulfide monofilament described above as at least a part of the warp and / or the weft, and exhibits more excellent surface smoothness in industrial fabrics.

  According to the present invention, as described below, it is possible to obtain a polyphenylene sulfide monofilament having high dimensional stability and excellent wear resistance and capable of providing an industrial fabric excellent in surface smoothness. The industrial fabric of the present invention using a sulfide monofilament as at least a part of warp and / or weft is excellent in surface smoothness. Therefore, a fabric for a conveyor belt, a dryer canvas fabric for papermaking, a fabric for filter, The present invention can be preferably applied to a net conveyor for a thermal bonding method nonwoven fabric bonding process, a papermaking wire, and the like.

The present invention is described in detail below.

The polyphenylene sulfide monofilament (hereinafter referred to as PPS monofilament) of the present invention has a shrinkage stress (cN) measured in accordance with ASTM 5591 as A, A is measured, and the shrinkage stress (cN) measured after cooling to 25 ° C. is measured. When B is satisfied, it is important to satisfy the following expression (a).
[BA] / Fineness (cN / dtex) ≦ 0.030 (a)

  In the present invention, it is important to set [BA] / fineness to 0.030 or less for the following reason.

  That is, as a result of investigating the cause of the phenomenon that wrinkles occur on the surface of the fabric at the moment when the fabric woven using a part of the PPS monofilament is heat-set and taken out in a room temperature atmosphere, this phenomenon is caused by the heat of the PPS monofilament. It was concluded that it was due to the shrinkage stress characteristics. PPS monofilament has a large change in shrinkage stress upon cooling after heating and is more conspicuous than polyester. For example, when interwoven with other monofilaments such as polyester, the PPS monofilament and polyester monofilament are cooled immediately after heat setting. Due to the difference in shrinkage stress, wrinkles were generated on the surface of the fabric, and the surface smoothness of the fabric was significantly lost.

  As a result of intensive studies, the present inventors have obtained high dimensional stability by improving the thermal contraction stress characteristics of the PPS monofilament accompanying a decrease in temperature, that is, by reducing the change in contraction stress generated during cooling after heating. I found out. That is, if the PPS monofilament in the above range is used, it is possible to obtain a woven fabric having excellent surface smoothness without causing wrinkles on the surface even after taking out in a room temperature atmosphere after heat setting. Also, if the change in shrinkage stress is outside the above range, the change in shrinkage stress during cooling after heating is large, so dimensional stability cannot be obtained, wrinkles and warpage occur on the fabric surface, and it is necessary and sufficient for industrial fabrics. It is not preferable because a smooth surface smoothness cannot be obtained.

  The PPS monofilament of the present invention preferably has a dry heat shrinkage at 180 ° C. of 8.0% or less. For PPS monofilaments with a high shrinkage of 8.0% or more, it is necessary to produce yarn at an extremely high draw ratio. Therefore, the degree of crystallinity becomes extremely high, and thread breakage occurs in the PPS monofilament, which leads to an undesirable result that the quality tends to be lowered.

  The PPS monofilament of the present invention is JIS. It is preferable that the number of reciprocating frictions at the time of fracture in the bending wear characteristic test measured in accordance with the regulations of L1095 is 7000 times or more. If it is 7000 times or less, the abrasion resistance necessary for an industrial fabric cannot be obtained, so that the life of the fabric is reduced, and the working efficiency is lowered, for example, the frequency of changing the fabric is not preferable.

  The PPS used in the PPS monofilament of the present invention means a polymer containing a phenylene sulfide unit in which the polymer repeating unit is composed of a p-phenylene sulfide unit or an m-phenylene sulfide unit. Among these polymers, a polymer in which 90% or more of the repeating units are composed of p-phenylene sulfide units is preferably used.

  PPS which can be particularly preferably used in the present invention can be produced by polycondensation reaction of sodium sulfide with p-dichlorobenzene. However, p-dichlorobenzene is co-polymerized with less than 10 mol% of trichlorobenzene as a branching component. It may be produced by condensation.

  Further, the PPS used in the present invention preferably has a polymer melt flow: melt flow rate (hereinafter referred to as MFR) measured by JIS K-6900 of 150 or less, preferably 50 to 110. If the MFR of PPS exceeds 150, the tensile strength of the resulting fiber tends to decrease. Conversely, if it is less than 50, the viscosity is too high and the pressure of the melt extruder rises abnormally and stable spinning can be performed. become unable.

  Here, as PPS which can be used as a commercial item, E1880, E2080, E2280, E2481, M2488, M2588, etc. of Toray Industries, Inc. can be mentioned, for example.

  PPS is usually obtained as a powder, but before being melt-spun, the powder PPS is heated to a temperature above its melting point with an extruder or the like, melted and kneaded, and then filtered to remove foreign substances as necessary. It can be extruded into a gut shape, cooled, and then processed into a pellet shape by a method such as cutting. The PPS powder or PPS pellets are preferably subjected to spinning after being dried at about 100 to 180 ° C. for about 5 to 24 hours under a vacuum.

  Furthermore, the PPS to be used includes various inorganic particles such as titanium oxide, silicon oxide, calcium carbonate, silicon nitride, clay, talc, kaolin, diriconium acid, and crosslinked polymer particles, as well as conventionally known antioxidants, various colorants, Waxes, silicone oils, various surfactants, various reinforcing fibers, fluororesins, polyesters, polyamides, polyolefins, and the like may be added.

  Next, a method for producing the PPS monofilament of the present invention having the above characteristics will be described.

  The production of the PPS monofilament of the present invention is carried out by using a known melt spinning machine, for example, a kneading extruder such as an extruder, or a melt spinning machine such as a pressure melter type, to melt and extrude a certain amount of PPS polymer from a spinneret. It is performed by cooling, stretching and heat setting.

  In particular, in order to obtain a PPS monofilament with improved heat shrinkage stress characteristics of the present invention, when PPS is melt-spun from a spinneret, the spun yarn is cooled and solidified, and then subjected to multistage drawing of two or more stages, It is important that the total draw ratio is in the range of 4.0 to 5.0 times, and more preferably in the range of 4.5 to 5.0 times.

  As described above, the present inventors have found that a high dimensional stability can be obtained by further reducing the shrinkage stress change that occurs during cooling after heating. It has been concluded that this can be achieved by minimizing the change in the specific volume of the PPS monofilament with the decrease in.

  PPS monofilament increases the degree of molecular orientation by performing multi-stage stretching of two or more stages, and improves the strength of the resulting monofilament. However, the change in specific volume accompanying a decrease in temperature differs depending on the degree of molecular orientation. The higher the degree, the smaller the change in specific volume. That is, the change in shrinkage stress generated during cooling after heating can be reduced, and high dimensional stability can be obtained. In general, a crystalline polymer such as PPS or polyester has a crystalline part and an amorphous part, but the change in specific volume with a decrease in temperature is different between the crystalline part and the amorphous part. The change in specific volume is small. That is, as the degree of crystallinity is lower, the change in specific volume can be minimized and high dimensional stability can be obtained. Furthermore, since the change in specific volume greatly depends on the degree of molecular orientation rather than the degree of crystallinity, it is preferable to set the draw ratio that greatly affects the degree of molecular orientation within the above range. Since the degree is low, the change in specific volume with a decrease in temperature becomes large, and not only dimensional stability cannot be obtained, but also the strength required for industrial fabrics cannot be obtained. On the other hand, if the draw ratio exceeds 5.0 times, thread breakage frequently occurs during spinning.

  In order to obtain the PPS monofilament having improved heat shrinkage stress characteristics of the present invention, the PPS is melt-spun from the spinneret, the spun yarn is cooled and solidified, and after the two-stage drawing, the heat setting is performed. It is important to keep the temperature below 200 ° C. When the heat set temperature exceeds 200 ° C., the change in shrinkage stress during cooling after heating increases due to crystallization, resulting in yarn cracking, and the target wear resistance cannot be obtained.

  Further, when performing the heat setting, it is important to set the heat setting magnification in the range of 0.90 to 1.00 times, and more preferably in the range of 0.95 to 0.97 times. . If the heat set magnification exceeds 1.00, the target dry heat shrinkage rate cannot be obtained, and if the heat set magnification is less than 0.90 times, slackness occurs in the yarn in the heat setting process, resulting in poor operability. Since it invites, it is not preferable.

   Here, it is important that the stretching ratio, the heat setting temperature, and the heat setting ratio satisfy all of these three conditions. If any one of these conditions is lacking, the desired dimensional stability, Either or all of wear and fabric surface smoothness cannot be achieved.

  The thickness of the PPS monofilament of the present invention thus obtained is not particularly limited, but is 0.05 to 3 mm, particularly 0.1 to 2.5 mm when used as an industrial fabric. Is preferred.

  Further, the cross-sectional shape of the PPS monofilament of the present invention is not particularly limited, and is circular, oval, triangular, square, flat, rhombus, half moon, pentagon or more polygon, multileaf, dog bone Examples thereof include a shape and a saddle shape, but in particular, when used as a constituent material of an industrial fabric, a circular shape, an oval shape, or a flat shape is preferable.

  The PPS monofilament of the present invention thus obtained has high dimensional stability due to improved heat shrinkage stress characteristics and excellent wear resistance. Therefore, the PPS monofilament has unique properties not found in conventional PPS monofilaments. Can be expressed.

  The industrial fabric of the present invention using the PPS monofilament of the present invention as at least a part of the warp and / or the weft, in particular, a transport belt fabric, a dryer canvas fabric for papermaking, a filter fabric, and a thermal bond method nonwoven fabric bonding step Net conveyors, papermaking wires, and the like can maintain better surface smoothness without wrinkling on the fabric surface even when taken out in a room temperature atmosphere after heat setting.

  EXAMPLES The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

  The physical properties described above and below are values measured by the following methods.

[Shrinkage stress change]
The shrinkage stress (cN) measured when a PPS monofilament applied with a load of 5 mN / tex in accordance with ASTM 5591 for 2 minutes in a dry heat atmosphere at 180 ° C. using a TST2 device manufactured by Lenzing Instruments is defined as A. Then, when the contraction stress (cN) measured when the PPS monofilament was cooled to 25 ° C. by natural heat radiation was B, the value obtained by the following formula (a) was defined as the contraction stress change (cN / dtex). . (The fineness in the formula means the fineness before measurement).
[BA] / Fineness (cN / dtex) ≦ 0.030 (a)

[Dry heat shrinkage]
JIS. It measured according to the prescription | regulation of the B method of the dry heat shrinkage rate item of L1013.

[Bending friction test]
JIS. In accordance with the provisions of L1095, a monofilament that was brought into contact with a fixed friction piece (hard steel wire (SWP-ASF)) having a diameter of 3 mm was provided obliquely downward so that the left and right sides of the friction piece were 55 °. It is hung under two free rollers (distance between rollers: 63.5 mm), and a load of 0.20 g per 1 dtex of monofilament is applied to one end of the monofilament via another free roller. The monofilament was contacted and reciprocated with the friction element at a reciprocating stroke of 105 mm / min and a reciprocating stroke of 20 mm, and the number of reciprocating frictions until the ten monofilaments were cut for each sample was measured to obtain an average value. It shows that it is so favorable that this average value is large.

[Spinning operability]
The state during continuous extrusion spinning was observed, and the frequency of yarn breakage in the drawing process was evaluated according to the following three criteria.
○ ・ ・ All were good.
△ ・ ・ Although there was yarn breakage, the operation was possible.
× ·· Many yarn breaks occurred, making operation extremely difficult.

[Evaluation of surface wrinkles of fabric]
For weaving the woven fabric, PPS monofilaments of Examples and Comparative Examples and polyethylene terephthalate monofilaments having the same diameter (580D type yarn manufactured by Toray Monofilament Co., Ltd.) were used. The PPS monofilament and the polyethylene terephthalate monofilament were woven in the weft direction of a double weave at a fiber ratio of 1: 1. Thereafter, heat setting was performed under three conditions of 140 ° C. for 10 minutes, 160 ° C. for 10 minutes, and 200 ° C. for 10 minutes, and the occurrence of surface defects was examined. The case where surface flaws did not occur was evaluated as ◯, and the case where surface flaws occurred was evaluated as ×.

[Example 1]
The dried PPS resin (E2080, manufactured by Toray Industries, Inc.) was supplied to a 40 mm single-screw extruder melt spinning machine, melted and kneaded at a temperature of 320 ° C., and then spun from the spinneret. Next, after the melted spun yarn was introduced into warm water to be cooled and solidified, it was heat-set at a heat drawing zone of hot air of 160 ° C. with a total draw ratio of 4.3 times, An oil agent was applied and wound on a bobbin to obtain a PPS monofilament having a diameter of 0.52 mm. Table 1 shows the shrinkage stress change, dry heat shrinkage rate, bending wear test, spinning operability, and fabric surface wrinkle evaluation of the obtained PPS monofilament.

[Examples 2 to 5]
A PPS monofilament having a diameter of 0.52 mm and a circular cross section was obtained in the same manner as in Example 1 except that the total draw ratio, heat setting ratio and heat setting temperature were changed as shown in Table 1.

[Comparative Examples 1-4]
A PPS monofilament having a diameter of 0.52 mm and a circular cross section was obtained in the same manner as in Example 1 except that the total draw ratio, heat setting ratio and heat setting temperature were changed as shown in Table 1.

  As is apparent from Table 1, the PPS monofilament in the present invention, that is, the PPS monofilament (Examples 1 to 5) having a small change in shrinkage stress has excellent wear resistance, and the fabric using the PPS monofilament of the present invention is heated. Even after cooling after setting, the surface of the fabric does not generate wrinkles and has excellent surface smoothness.

  On the other hand, PPS monofilaments that are outside the present invention, that is, PPS monofilaments with a large change in shrinkage stress (Comparative Examples 1, 3, and 4) and the like, wrinkles occur on the surface of the fabric during cooling after heat setting. It turns out that it does not have the surface smoothness calculated | required as a textile for use. In addition, the PPS monofilament (Comparative Example 2), which has a low shrinkage stress change but is outside the present invention, has not only low spinning operability, but also does not have the abrasion resistance necessary for industrial fabrics.

  Since the PPS monofilament of the present invention has improved heat shrinkage stress characteristics, it has higher dimensional stability and superior wear resistance than conventional ones. The monofilament of the present invention is used as a transport belt fabric and a papermaking dryer canvas fabric. Excellent surface smoothness can be realized when used for at least part of warp and / or weft of industrial fabrics such as filter fabrics, thermal bond nonwoven fabric bonding process net conveyors, and papermaking wires.

Claims (5)

When the contraction stress (cN) measured according to ASTM 5591 is A, and A is measured and the contraction stress (cN) measured after cooling to 25 ° C. is B, the following equation (a) is satisfied. Characteristic polyphenylene sulfide monofilament.
[BA] / Fineness (cN / dtex) ≦ 0.030 (a) The polyphenylene sulfide monofilament according to claim 1, wherein the dry heat shrinkage at 180 ° C is 8.0% or less. JIS. 3. The polyphenylene sulfide monofilament according to claim 1, wherein the number of reciprocating frictions at the time of breaking in a bending wear characteristic test measured in accordance with the regulations of L1095 is 7000 times or more. After melt spinning polyphenylene sulfide, when performing two-stage stretching and heat setting, the total stretching ratio is 4.0 to 5.0 times, the heat setting temperature is 200 ° C. or less, and the heat setting ratio is 0.90 to 1.00. It is set as conditions, The manufacturing method of the polyphenylene sulfide monofilament of any one of Claims 1-3 characterized by the above-mentioned. A woven fabric comprising the polyphenylene sulfide monofilament according to any one of claims 1 to 3 as at least a part of warp and / or weft.