JP2008101287A - Monofilament for screen gauze - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a monofilament which has good weaving stability, when processed, is excellent in continuous printing performance as screen gauze, and is suitable for obtaining a high mesh high modulus screen gauze requiring high accuracy. <P>SOLUTION: The sheath-core type conjugated polyester monofilament for screen gauze satisfies the following: the largest point strength of a raw filament before a thermal treatment is 5.5 to 8.0 cN/dtex; the strength at an elongation of 5% is 3.5-5.0 cN/dtex; the largest point elongation is 20-35%; the wet heat shrinkage percent is 2.5-9.0%; the largest point strength of the raw filament after a wet heat treatment is 5.0-7.5 cN/dtex; the strength at an elongation of 15% is 4.0-7.0 cN/dtex; the largest point elongation is 20 to 40%; the intrinsic viscosity of a core side polyester is 0.70-1.00 dL/g; the intrinsic viscosity of a sheath side polyester is 0.40-0.55 dL/g; knotted filaments are lower than a specific number. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a monofilament having a modified surface. More specifically, the present invention relates to a monofilament suitable for obtaining a high mesh and high modulus screen wrinkle required for high precision such as mesh fabric for screen printing, production of printed wiring board and the like.

  Monofilaments have been widely used not only in the clothing field but also in the industrial material field. Examples of applications in the latter field of industrial materials in particular include monofilaments as raw yarns for tire cords, ropes, nets, tegus, tarpaulins, tents, screens, paragliders and sailcloths. The physical properties required for these monofilaments are becoming stricter, and improvements such as adhesion to rubber, fatigue resistance, dyeability, abrasion resistance, and knot strength are being urged. Especially in recent printing in the electronic circuit field, the degree of integration is increasing, and the demand for high strength, high modulus, and high mesh is increasing in order to improve the printing density and printability of screens. ing. The raw yarn is also required to have high strength, high modulus, and fineness.

  In designing screen silk yarn, Patent Document 1 (Japanese Patent Application Laid-Open No. 2-289120) describes the breaking strength and breaking elongation of polyester core-sheath monofilament, the modulus when stretched by 10%, and the polyester of the sheath portion. It has been proposed that Tg is specified, the core portion has high modulus and high strength, and the sheath portion prevents yarn scraping due to wrinkles during weaving and the occurrence of scum. It is possible to obtain a high-strength, high-modulus screen wrinkle with this method and to reduce thread shaving. However, in the production of the screen wrinkle, when the process of texture adjustment, moist heat setting and tensioning is passed, Since the yarn shrinks and the load curve of the yarn becomes different from that before shrinkage, the dimensional stability as a screen wrinkle is poor and there is a problem in continuous printability.

The same document proposes a polyester having a low Tg as a sheath component, particularly a copolyester. However, screen wrinkles are often dyed, and the copolyester has poor dyeing fastness so that it oozes out during printing. There was also a problem.
JP-A-2-289120

  The present invention provides a polyester monofilament suitable for mesh fabrics used for screen printing. To provide a monofilament suitable for obtaining a high-mesh, high-modulus screen wrinkle that is particularly excellent in weaving stability during processing and continuous printing performance as a screen wrinkle and requires high precision.

The core-sheath type composite polyester monofilament satisfying the following A to H.
A. Monofilament maximum strength before wet heat treatment of 5.5 to 8.0 cN / dtex, strength at 5% elongation of 3.5 to 5.0 cN / dtex, maximum elongation of 20 to 35%, wet heat The shrinkage rate is 2.5 to 9.0%.
B. The monofilament has a maximum yarn point strength after wet heat treatment of 5.0 to 7.5 cN / dtex, a strength at 15% elongation of 4.0 to 7.0 cN / dtex, and a maximum elongation of 20 to 40%. thing.
C. The intrinsic viscosity of the core side polyester is 0.70 to 1.00 dL / g.
D. The intrinsic viscosity of the sheath side polyester is 0.40 to 0.55 dL / g.
E. The birefringence of the sheath side polyester is 140 × 10 ^{−3 to} 170 × 10 ⁻³ .
F. The core-sheath area ratio of the cross section orthogonal to the fiber axis is 30:70 to 70:30.
G. The filament single yarn fineness is 4 to 24 dtex.
H. The number of knots is 1.1 or more times the fiber diameter in the monofilament longitudinal direction of 500,000 meters.

  By designing the physical properties of monofilament yarn before and after wet heat treatment as in the present invention, it is possible to obtain a high-mesh, high-modulus screen wrinkle with excellent weaving stability, dimensional stability as a screen wrinkle, and continuous printing performance. it can.

  A fine filament monofilament of 24 dtex or less is used for a high mesh screen (200 to 500 mesh) suitable for precision printing. The filaments for woven fabrics must have specific properties such as strength and elongation enough to suppress the occurrence of deterioration in weaving properties and the elongation of screen creases during printing (decrease in dimensional stability). In general, the performance is evaluated by the stress (modulus, hereinafter 5% LASE) when the elongation of the raw yarn is 5%. However, in order to obtain a higher degree of dimensional stability, the present inventor In addition, it has been found that it is important to consider the influence of the raw yarn on the wet heat treatment in the production process of the screen koji. (Humidity heat treatment means that the woven screen cocoon is usually treated with warm water and steam during the refining and dyeing treatments.) The monofilament for the screen cocoon of the present invention is based on these findings. And a core-sheath type composite polyester monofilament having a single yarn fineness of 4 to 24 dtex with a high IV polyester as a core component and a low IV polyester as a sheath component, and having a maximum point strength before wet heat treatment of 5.5 to 5.5 8.0 cN / dtex 5% stretch strength 3.5-5.0 cN / dtex, maximum point elongation 20-35%, wet heat shrinkage 2.5-9.0%, after wet heat treatment The maximum point strength is 5.0 to 7.5 cN / dtex, the strength at 15% elongation (modulus, hereinafter 15% LASE) is 4.0 to 7.0 cN / dtex, and the maximum point elongation is 20 to 4 By% to, after the step has elapsed weave adjustments and wet heat set or gauze-covered as screen mesh cloth may be a screen mesh having excellent highly dimensional stability. The maximum point strength and elongation mean strength and elongation at the time of cutting in the unloading curve of the raw yarn.

  The screen filament monofilament of the present invention uses 0.7 to 1.0 dL / g high IV polyester on the core side and 0.40 to 0.55 dL / g polyester on the sheath side, and uses a normal composite spinning apparatus. It is used as a core-sheath monofilament. The cross section perpendicular to the fiber axis is preferably a circular cross section. Although the core and the sheath part in the cross section do not need to be similar, the core part needs to be sufficiently covered with the sheath part. A preferable core: sheath area ratio is 30:70 to 70:30.

  High IV and high modulus can be obtained by setting the IV of the polyester at the core to 0.7 or more, and soft by setting the IV of the polyester at the sheath to 0.45 to 0.55. Yarn cutting due to wrinkles during weaving can be improved.

  Examples of the polyester used include aromatic polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), and any of them may be used. Among these, PET is most preferred in terms of operability and cost when performing melt spinning.

The monofilament of the present invention has a maximum point strength before wet heat treatment of 5.5 to 8.0 cN / dtex, 5% LASE of 3.5 to 5.0 cN / dtex, maximum point elongation of 20 to 35%, wet heat shrinkage Is required to be designed to be 2.5 to 9.0%.
A higher 5% ASE is preferable, but if it exceeds 5.0 cN / dtex, it is not preferable because scraping due to wrinkles occurs during weaving and is woven into the woven fabric, resulting in a defect. On the contrary, if it is 3.5 cN / dtex or less, the dimensional stability at the time of continuous screen printing becomes poor, the misalignment is likely to occur, and it becomes a defect of the printed matter, which is not preferable.

When the maximum point strength after wet heat treatment is 5.0 cN / dtex or less, the screen wrinkle strength is insufficient, the dimensional stability at the time of continuous screen printing is deteriorated, and misalignment is likely to occur. The separation is not good. If it is 7.5 cN / dtex or more, scraping due to wrinkles easily occurs during weaving.
On the other hand, if the maximum point elongation is less than 20%, the yarn handleability deteriorates, such as frequent weaving of woven yarn. If the maximum point elongation is 40% or more, wrinkle elongation tends to occur.

The wet heat shrinkage rate is preferably in the range of 2.5 to 9.0%. Outside this range, 15% LASE after the wet heat treatment cannot be within a specific range, which is not preferable. (This is based on the correlation between the 15% LASE of the yarn after the wet heat treatment and the dimensional stability of the screen ridge after the wet heat treatment, and the 15% LASE of the monofilament of the present invention after the wet heat treatment is 4.0 to 4.0. 7.0 cN / dtex)
Although the specific manufacturing method for obtaining the monofilament of this characteristic is demonstrated, it is not necessarily limited to this.

  The above-mentioned two kinds of intrinsic viscosity polyesters are melt-spun using a composite spinneret by a conventional method to obtain a core-sheath monofilament, followed by stretching. Although it can be wound up as an unstretched yarn once in the spinning process and used for the stretching process, it is preferable to perform stretching in direct connection with the spinning process.

  In direct spinning drawing, it is preferable to use several pairs of heated rolls and draw in one or more stages, and finally, the draw ratio is determined so that the strength, elongation, and shrinkage rate fall within a predetermined range. This stretching can include a relaxation treatment such as relaxing stretching, and the wet heat shrinkage rate can be adjusted to fall within a predetermined range.

  In this way, the properties of the original yarn before weaving are adjusted, and then subjected to the weaving process, and if necessary, shrinkage is performed through wet heat treatment such as refining, dyeing, etc., and the yarn has a predetermined high elongation after wet heat shrinkage. The screen has a high degree of dimensional stability.

  Nodes generated on the surface of the monofilament are undesirable because they cause yarn breakage and scum during weaving, and it is necessary to prevent them from occurring as much as possible. As the cause of the knot, there are unmelted foreign matters contained in the polymer and deterioration of the polymer itself. About the unmelted foreign material in a polymer, the discharge | emission can be suppressed or disperse | distributed by forming a filtration layer from a pack entrance to a nozzle | cap | die discharge port. About this filtration layer, the opening amount of about 20 to 30% of the monofilament diameter is preferable, and if it is 20% or less, abnormal pressure is applied in the pack, leading to breakage of the parts in the pack and the pack body. If it is 30% or more, unmelted foreign matter, which is the main cause of knot yarn, is contained in the yarn as coarse particles, and the risk of knot generation increases. In addition, with regard to the deterioration of the polymer itself, with regard to polymer feeding, the bending of the pipe is reduced, the time from introduction of the pack to discharge is within 1 minute, and the amount of heat received by the polymer is reduced as much as possible to reduce the risk of occurrence of nodes be able to.

The present invention will be described more specifically with reference to the following examples.
In Examples, intrinsic viscosity, strength, elongation, shrinkage rate during wet heat treatment, strength after wet heat treatment, elongation after wet heat treatment, strength at 15% elongation, evaluation of the number of nodes, evaluation of thread scraping, hysteresis Evaluation was performed according to the following definitions.

Intrinsic viscosity:
Dilution solutions of each concentration (C) in which the sample was dissolved in orthochlorophenol at 35 ° C. were prepared, and C was brought close to 0 from the viscosity (ηr) of these solutions by the following formula.
η = limit (ln (ηr / C))
In addition, each component of the core sheath is equivalent to the base used at the time of yarn production and the residence time in melting, and a base designed so that the core and sheath polymers can be discharged separately has been sufficiently stabilized. Above, the release polymer was sampled and measured.

Strength and elongation:
The strength and elongation of the fiber are the strength and elongation when the sample breaks in accordance with JIS-L1017, measured using a Tensilon manufactured by Orientec Co., Ltd. at a sample length of 25 cm and an elongation rate of 30 cm / min. For 5% ASE, the stress was measured when the sample at the time of the above measurement was stretched by 5%.

Shrinkage rate during wet heat treatment:
5000 m was sampled and placed in a skein state, and placed in a high-pressure, 130 ° C., moist heat atmosphere for 10 minutes while applying a fineness × 0.1 times (g). The yarn after the treatment was naturally dried and the yarn length was measured again. The yarn length after the treatment was divided by the yarn length of 5000 m before the treatment, and the percentage of shrinkage after the wet heat treatment was expressed as a percentage.

Strength after wet heat treatment, elongation, 15% elongation stress (LASE):
The strength and elongation of the fiber after wet heat treatment are the strength and elongation when the yarn after wet heat treatment is measured using a Tensilon made by Orientec Co., Ltd. with a sample length of 25 cm and an elongation rate of 30 cm / min, and the sample is broken. . For 15% ASE, the stress was measured when the sample at the time of the above measurement was stretched by 15%.

Evaluation of the number of clauses:
In front of the dropper installed at the creel outlet of the warping machine, 12 slit guides having a clearance of thread diameter × 1.1 times and a tolerance of ± 2 μm were installed. Threads were passed through the slit guide, and 12 yarns × 8 stages = 96 yarns were warped at a yarn speed of 500 m / min, and each yarn length was 200,000 m. At that time, the number of yarn breaks with the slit guide was regarded as the number of knots, and the number of yarn breaks during warping was measured. Evaluation was performed by converting the detected number of times of yarn breakage into a yarn length of 100,000 m.

Evaluation of thread cutting:
A mesh fabric was woven using 300 warps per inch of weaving width with a slewer type loom at a rotation speed of 250 rpm, and the woven fabric was visually inspected with the inspection machine. At this time, the number of fabric defects in which the mesh pattern that normally appears black was whitened was counted and evaluated.
Less than 5 defects caused by thread cutting per woven width 1.5 m × woven fabric length 300 m were evaluated as “◯”, 5 or more and less than 10 as “Δ”, and 10 or more as “×”.

Hysteresis evaluation (screen 紗 dimensional stability substitute characteristics):
A load at the time of 7% elongation is applied as an initial load to the raw yarn after the wet heat treatment, and then the load (B) when the 1.5% continuous elongation is further increased 1000 times is compared with the load (A) at the 30th time, C = The value of C obtained by B / A × 100 is 98% or less.

[Example 1]
Using polyethylene terephthalate with an intrinsic viscosity of 0.87 dL / g on the core side and polyethylene terephthalate with an intrinsic viscosity of 0.50 dL / g on the sheath side, both melt at a temperature of 295 ° C. The intrinsic viscosity on the core side sampled 2 hours after the start of discharge was 0.75 dL / g, and the intrinsic viscosity on the sheath side was 0.44 dL / g. While being wound at a spinning speed of 1200 m / min, an unstretched yarn was obtained while attaching an oil agent with an oiling roller. Then, after preheating with a heated hot roller, it is stretched at 3.8 times while being heated at 200 ° C. with a slit heater, subjected to a relaxation treatment of 0.03 times, wound up, and stretched with 13 dtex-1 file. Obtained. The obtained drawn yarn has a strength of 6.1 cN / dtex, an elongation of 25%, a 5% ASE of 4.0 cN / dtex, a wet heat shrinkage of 7.0%, and a strength after boiling water treatment of 6.0 cN / dtex, an elongation of 32. %, 15% LASE was 4.5 cN / dtex. The number of node yarn generation of the raw yarn was zero. When this raw yarn was woven with a slewer type loom, the number of fabric defects due to the occurrence of yarn shaving was 0 per 300 m. Hysteresis evaluation was (circle). When the finished screen koji was continuously printed, it had little elongation and excellent dimensional stability.

[Comparative Example 1]
In Example 1, relaxation stretching was stopped, 1.2-fold stretching was performed at that portion, and the obtained stretched yarn was combined with 13 dtex. The obtained drawn yarn has a strength of 6.5 cN / dtex, an elongation of 18%, a 5% ASE of 5.2 cN / dtex, a wet heat shrinkage of 10.0%, a strength after boiling water treatment of 6.1 cN / dtex, and an elongation of 40. %, 15% LASE was 3.8 cN / dtex. The number of node yarn generation of the raw yarn was zero. When this raw yarn was woven with a slewer type loom, the number of fabric defects due to the occurrence of yarn shaving was 5 pieces per 300 m, and the hysteresis evaluation was x. When the finished screen wrinkle was continuously printed, the elongation was large and it was subject to dimensional stability.

[Example 2]
In Example 1, a drawn yarn was obtained in the same manner as in Example 1 except that the slit heater temperature at the time of drawing was changed from 200 to 230 ° C. The obtained drawn yarn had a strength of 6.2 cN / dtex, an elongation of 24%, a 5% ASE of 4.1 cN / dtex, a wet heat shrinkage of 6.0%, a strength after boiling water treatment of 6.1 cN / dtex, and an elongation of 32. %, 15% LASE was 5.0 cN / dtex. The number of node yarn generation of the raw yarn was zero. When this raw yarn was woven with a slewer type loom, the number of fabric defects due to the occurrence of yarn shaving was 0 per 300 m. Hysteresis evaluation was (circle). When the finished screen koji was continuously printed, it had little elongation and excellent dimensional stability.

[Comparative Example 2]
In Example 1, a drawn yarn was obtained in the same manner as in Example 1 except that the slit heater temperature at the time of drawing was changed from 200 to 150 ° C. The obtained drawn yarn has a strength of 5.5 cN / dtex, an elongation of 24%, a 5% ASE of 3.5 cN / dtex, a wet heat shrinkage of 13.0%, a strength after boiling water treatment of 5.3 cN / dtex, and an elongation of 45. %, 15% LASE was 3.0 cN / dtex. The number of node yarn generation of the raw yarn was zero. When this raw yarn was woven with a slewer type loom, the number of fabric defects due to the occurrence of yarn shaving was 0 per 300 m. When the finished screen wrinkle was continuously printed, the elongation was large and it was subject to dimensional stability.
The results of Examples 1-2 and Comparative Examples 1-2 are summarized in Table 1.

  The present invention relates to a monofilament having a modified surface, and in particular, to obtain a high-mesh, high-modulus screen wrinkle that requires a high degree of precision, such as a mesh fabric for screen printing and the production of a printed wiring board. It is suitable for.

Claims (2)

A core-sheath type composite polyester monofilament for a screen bag characterized by satisfying the following A to H.
A. Monofilament maximum strength before wet heat treatment of 5.5 to 8.0 cN / dtex, strength at 5% elongation of 3.5 to 5.0 cN / dtex, maximum elongation of 20 to 35%, wet heat The shrinkage rate is 2.5 to 9.0%.
B. The monofilament has a maximum yarn point strength after wet heat treatment of 5.0 to 7.5 cN / dtex, a strength at 15% elongation of 4.0 to 7.0 cN / dtex, and a maximum elongation of 20 to 40%. thing.
C. The intrinsic viscosity of the core side polyester is 0.70 to 1.00 dL / g.
D. The intrinsic viscosity of the sheath side polyester is 0.40 to 0.55 dL / g.
E. The birefringence of the sheath side polyester is 140 × 10 ^{−3 to} 170 × 10 ⁻³ .
F. The core-sheath area ratio of the cross section orthogonal to the fiber axis is 30:70 to 70:30.
G. The single yarn fineness is 4 to 24 dtex.
H. The number of knots is 1.1 or more times the fiber diameter in the monofilament longitudinal direction of 500,000 meters.   A load at the time of 7% elongation is applied to the original yarn after the wet heat treatment as an initial load, and then the load (B) when the 1.5% continuous elongation is further increased 1000 times is compared with the load (A) at the 30th time, C The core-sheath type composite monofilament for screen wrinkles according to claim 1, wherein the strength deterioration (C) obtained by = (A-B) / Ax100 is 0 to 1%.