JP2009256822A - Monofilament for screen gauze - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a monofilament for a high-mesh and high-modulus screen gauze which hardly forms scum at weaving. <P>SOLUTION: The core-sheath type conjugate polyester monofilament for the screen gauze satisfies the following requirements (A) to (F): (A) sheath-side polyester is a copolyester obtained by copolymerizing 0.5-25 mol% isophthalic acid and/or sulfoisophthalic acid metal salt based on the whole acid component of the polyester; (B) the strength at the maximum point of a raw thread after moist heat treatment of the monofilament, the strength at 15% elongation, and the elongation at the maximum point are 5.0-7.5 cN/dtex, 4.0-7.0 cN/dtex, and 20-40%, respectively; (C) the intrinsic viscosity of the core-side polyester is 0.70-1.00 dL/g; (D) the intrinsic viscosity of the sheath-side polyester is 0.40-0.55 dL/g; (E) the birefringence of the sheath-side polyester is 0.03-0.14; and (F) the core/sheath area ratio in the cross-section orthogonal to the fiber axis is from 50:50 to 95:5. <P>COPYRIGHT: (C)2010,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 which requires high precision and continuous printability such as manufacturing of a printed wiring board.

  Monofilaments have been widely used not only in the clothing field but also in the industrial material field. An example of the latter application in the field of industrial materials is screen printing mesh fabric. 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 printing precision and printability as a screen bottle. ing. The raw yarn is also required to have high strength, high modulus, and fineness.

  In designing the yarn for screen wrinkles, it is important to prevent yarn scraping and scum generation due to wrinkles at the time of weaving the mesh fabric. As a countermeasure, in JP-A-2-289120, in the polyester core-sheath monofilament, By taking a high modulus and high strength at the core, and using polyester with a Tg of 35 to 73 ° C. as the polyester of the sheath, it is possible to prevent thread shaving and scum generation due to wrinkles during weaving at the sheath, It has been proposed to use a high modulus screen silk yarn.

  As a measure for preventing the occurrence of scum, JP-A-11-241227 proposes a copolyester having a sheath component IV (intrinsic viscosity) of 0.60 to 0.80 and a pigat softening temperature of 67 to 78 ° C. ing. Although there is an effect of preventing scum by some degree of soft polyester, it has not been completely prevented. Moreover, since the softening temperature was too low, there was a problem that the fibers were easily fused.

  Japanese Patent Laid-Open No. 2003-213527 proposes that the intrinsic viscosity difference between the core component and the sheath component of the core-sheath composite monofilament is 0.25 or more, and if the intrinsic viscosity difference is 0.25 or more, the draw ratio is low. It can be set. However, in order to obtain a high-strength, high-modulus monofilament, it is necessary to increase the draw ratio, and there is a problem that it is difficult to form a high modulus high mesh screen 紗, and a problem that heat shrinkability increases because the draw ratio is lowered. It was. Further, since the viscosity difference is large, there is a problem that the core area and the sheath area in the cross section orthogonal to the fiber axis direction are easily changed, and the high density screen printing accuracy is lowered.

  Japanese Patent Application Laid-Open No. 2004-232182 proposes that the birefringence of the sheath component of the core-sheath composite monofilament be 0.18 or less. Certainly, since the degree of orientation is lowered by lowering the birefringence of the sheath component, the scum prevention is improved to some extent, but it is not satisfactory.

  Further, in Japanese Patent Application Laid-Open No. 2005-47020, the core area and the sheath area in the cross section orthogonal to the fiber axis direction are set to core / sheath = 70/30 to 90/10, and the intrinsic viscosity of the core component is 0.9 to 1. 3. It has been proposed as a preferable condition that the intrinsic viscosity of the sheath component is 0.45 to 0.75. Certainly, the sheath component was soft and scum was not easily generated, but it was not perfect.

JP-A-2-289120 Japanese Patent Laid-Open No. 11-241227 JP 2003-213527 A JP 2004-232182 A JP-A-2005-47020

  The present invention relates to a polyester monofilament suitable for a high mesh high modulus woven fabric for screen printing. Particularly, in a core-sheath type polyester monofilament, there is little thread scraping and scum generation during screen weaving, and a cross section perpendicular to the fiber axis direction. A core-sheath type polyester monofilament for screen wrinkles having a uniform fiber diameter with a stable core / sheath area ratio is provided.

The present invention solves the problems in the prior art,
That is, according to the present invention,
A core-sheath type composite polyester monofilament for screen cocoons characterized by satisfying the following AF.
A. The sheath side polyester is a copolymerized polyester obtained by copolymerizing the third component in an amount of 0.5 to 25 mol% with respect to the polyester total acid component and / or the total diol component.
B. The monofilament has a maximum yarn 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 0.03 to 0.14.
F. The core-sheath area ratio of the cross section orthogonal to the fiber axis is 50:50 to 95: 5.
Is provided.

  Here, the third component is preferably at least one selected from the group consisting of isophthalic acid, neopentyl glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, and propylene oxide adduct of bisphenol A.

  By making the sheath side polyester of the core-sheath type polyester monofilament of the present invention into a copolyester obtained by copolymerizing a specific component, and by using a raw yarn with a specific viscosity and a core / sheath area ratio specified, the birefringence index is a specific value. In addition to preventing the occurrence of scum during weaving, the texture and dimensional stability of the screen can be improved, and a high mesh and high modulus screen can be obtained with excellent continuous precision printing performance. it can.

The present invention will be described in detail.
The monofilament for screen scissors of the present invention uses a polyester having a high intrinsic viscosity of 0.7 to 1.0 dL / g (hereinafter, the intrinsic viscosity may be abbreviated as IV) on the core side, and 0.40 to 0 on the sheath side. A low-IV polyester of .55 dL / g is used to obtain a core-sheath monofilament using a normal core-sheath composite spinning apparatus.

  Examples of the polyester used in the core of the core-sheath polyester monofilament of the present invention include aromatic polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN). Good. Among these, PET is most preferred in terms of operability and cost when performing melt spinning.

  The IV of the polyester in the core needs to be 0.7 to 1.0 dL / g, and if it is less than 0.7, the strength of the yarn as a monofilament for screen wrinkles is insufficient, while the value exceeds 1.0 Is not preferable because the viscosity difference from the sheath polyester becomes too large and the core / sheath area is not appropriate (the core increases). Preferably it is 0.7-0.95 dL / g.

  The polyester of the sheath portion of the core-sheathed polyester monofilament of the present invention has terephthalic acid as the main acid component and at least one glycol, preferably at least one alkylene selected from ethylene glycol, trimethylene glycol, and tetramethylene glycol. Polyester having glycol as the main glycol component is copolymerized with at least one selected from the group consisting of isophthalic acid, neopentyl glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A and propylene oxide adduct of bisphenol A as the third component. It is necessary to make it polyester. Of these, isophthalic acid is preferred.

  To copolymerize at least one selected from the group of isophthalic acid, neopentyl glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, and propylene oxide adduct of bisphenol A into the polyester main chain, the polyester described above is used. The above compound may be added at any stage before the synthesis of is completed, preferably at any stage before the completion of the first stage reaction.

  At least one selected from the group consisting of isophthalic acid, neopentyl glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, and propylene oxide adduct of bisphenol A is 0 for all corresponding acid components and all glycol components of the polyester. It is necessary to use it at a ratio of 5 to 25 mol%. If at least one selected from the group of isophthalic acid, neopentyl glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, and propylene oxide adduct of bisphenol A is less than 0.5 mol%, the intrinsic viscosity is 0.45. Even if it is 0.55, the viscosity at the time of spinning becomes high, the birefringence increases, the core / sheath area ratio tends to fluctuate, and the spinning process tone is lowered. On the other hand, if it exceeds 25%, the heat shrinkage of the raw yarn becomes high, which is not preferable. Preferably it is 1.0 to 20%, More preferably, it is 5 to 15%.

  The IV of the copolyester of the sheath needs to be 0.45 to 0.55, and when it is within this range (because it is soft), scum generation due to wrinkles during weaving and thread scraping can be prevented. . If it is less than 0.45, the heat resistance is lowered, which is not preferable. When it exceeds 0.55, the viscosity at the time of spinning becomes high and the birefringence becomes high, which is not preferable.

  The effect of copolymerizing the third component is that, by copolymerization, there is little increase in viscosity during spinning, the birefringence can be lowered, the core / sheath area ratio is stabilized, and the occurrence of scum can be reduced. In addition, there is little occurrence of yarn breakage and fluff. When the third component is not copolymerized, even at the same intrinsic viscosity, the viscosity increase during yarn production is large and the birefringence is high, and the core / sheath area ratio is likely to fluctuate. descend.

  The cross section perpendicular to the fiber axis of the core-sheath polyester monofilament of the present invention 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 preferred core: sheath area ratio is 50:50 to 95: 5. When the core / sheath area ratio is lower than 50:50 and the core area is small, the strength is insufficient, which is not preferable. When the core area increases beyond 95: 5, a portion that is not covered by the sheath portion is generated and scum is generated.

The core-sheath monofilament of the present invention has a maximum point strength before wet heat treatment of 5.0 to 7.0 cN / dtex, 5% LASE of 2.5 to 3.7 cN / dtex, maximum point elongation of 20 to 45%, wet heat The shrinkage rate is preferably 2.5 to 9.0%.
5% LASE is preferably higher, but if it exceeds 3.7 cN / dtex, it is not preferable because scraping due to wrinkles occurs during weaving and is woven into the woven fabric, resulting in defects. Conversely, if it is 2.5 cN / dtex or less, the elongation of the screen wrinkles increases, which is not preferable.

When the maximum point strength is 5.0 cN / dtex or less, the screen wrinkle strength is insufficient, and tearing is likely to occur during tensioning. It becomes easy to do.
On the other hand, when the maximum point elongation is less than 20%, the thread handling property is deteriorated, such as frequent yarn breakage during weaving. If the maximum point elongation is 45% or more, wrinkle elongation tends to occur.

  The wet heat shrinkage rate is preferably in the range of 2.5 to 9.0%, and 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 core-sheath monofilament of the present invention after the wet heat treatment is 4. 0-7.0 cN / dtex is required)

Although the specific manufacturing method for obtaining the core-sheath-type polyester monofilament of such a characteristic is demonstrated, it is not necessarily limited to this.
The above-mentioned two types of polyester are melt-spun using a known core-sheath composite spinneret to form a core-sheath monofilament, followed by stretching to obtain a raw yarn having the above physical properties. Although it can be wound up as an undrawn yarn once in the spinning step and used for the drawing step, it is preferable to carry out drawing in direct connection with the spinning step.

  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 core-sheath monofilament of the present invention are undesirable because they cause yarn breakage and scum generation during weaving, and need to be prevented 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. The filtration layer preferably has an opening of about 10 to 15% of the monofilament diameter, and if it is 10% 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 15% or more, unmelted foreign matters that are the main cause of knotting are contained in the yarn as coarse particles, and the risk of knotting 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.

Birefringence index It calculated | required with the interference fringe method using the interference microscope (The Carl Zeiss Jena Co., Ltd. interfaco interference microscope). An immersion liquid having a desired refractive index was used. From the obtained interference fringe photograph, the refractive index was calculated from the following equation based on the interference fringe spacing and the deviation.
λd / D = (n−N) t
Where d: interference fringe shift, D: interference fringe spacing, λ: measurement light source wavelength, n: sample refractive index, N: solution refractive index, t: sample wire diameter
This analysis was performed with 10 points of 0.1 intervals between the radius (r = a / A) 0 to 0.9, where the radius of the monofilament is A and the distance from the central axis is a. "Technology of fiber / polymer measurement method": Performed according to the method described by Asakura Shoten, and calculated the refractive index in the direction parallel to the monofilament axial direction and the refractive index in the vertical direction of the sample from the following formula. .
Birefringence (Δn) = Parallel refractive index−Vertical refractive index
In addition, the birefringence of r = 0 was set as the birefringence value of the core component, and the birefringence of r = 0.9 was set as the birefringence value of the sheath component. It was confirmed on the monofilament cross-section that r = 0 was the birefringence of the core, and r = 0.9 was the birefringence of the sheath component.

Raw yarn strength and elongation:
The strength and elongation of the raw yarn are based on JIS-L1017, measured with a sample length of 25 cm and an elongation rate of 30 cm / min using Tensilon manufactured by Orientec Co., Ltd., and the strength and elongation when the sample breaks. 5% LASE measured the stress when the sample at the time of the above measurement was extended by 5%.

Wet heat shrinkage:
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. The case where 10% or less was rated as ◯ and the case where it exceeded 10% was rated as x.

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 scum generation and thread shaving:
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]
Preparation of sheath component copolyester:
100 parts of dimethyl terephthalate, 66 parts of ethylene glycol, isophthalic acid in the amount shown in Table 1 (mol% relative to the total acid component), acetic acid, 0.03 part of manganese tetrahydrate (0.024 mole relative to dimethyl terephthalate) %) Was charged into a transesterification can and the temperature was raised from 140 ° C. to 230 ° C. over 4 hours in a nitrogen gas atmosphere, and the produced methanol was subjected to a transesterification reaction while distilling out of the system. Subsequently, a 56% aqueous solution of normal phosphoric acid, 0.03 part (0.033 mol% based on dimethyl terephthalate) and 0.04 part (0.027 mol%) of antimony trioxide were added to the obtained product. And transferred to a polymerization can. Next, the pressure was reduced from 760 mmHg to 1 mmHg over 1 hour, and at the same time, the temperature was raised from 230 ° C. to 280 ° C. over 1 hour 30 minutes. Polymerization was carried out under a reduced pressure of 1 mmHg or less until an intrinsic viscosity of 0.58 dL / g was reached at a polymerization temperature of 280 ° C.

Core component polyester:
Polyethylene terephthalate having an intrinsic viscosity of 0.97 dL / g was used.

Preparation of core-sheath monofilament yarn production was performed as follows. Each of the above-mentioned dry polymers was melted by a conventional method in a spinning facility, and supplied to a two-component composite spinning head via a gear pump. The area ratio of the cross section perpendicular to the fiber axis direction of the core and the sheath polymer was set so as to have the value shown in Table 1. The molten polymer in the core and sheath supplied at the same time is cooled and solidified from the spinneret having one circular composite spinning hole with a nozzle hole diameter of 0.25 mm with cooling air from a normal cross-flow type spinning cylinder, and then spun. An undrawn yarn was obtained while applying an oil agent and attaching the oil agent with an oiling roller while winding at a spinning speed of 1200 m / min. 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. Table 1 shows the properties of the raw yarn obtained.

  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.

[Example 2]
The same procedure as in Example 1 was performed except that the core / sheath area ratio was 90/10.

[Example 3]
The same procedure as in Example 1 was performed except that the core / sheath area ratio was 55/45.

[Example 4]
The same procedure was carried out except that the sheath component polyester in Example 1 was obtained by copolymerizing 2.0 mol% of bisphenol A ethylene oxide adduct with respect to all glycol components.

[Example 5]
The same procedure as in Example 1 was performed except that the number of moles of copolymerized isophthalic acid was 5 mol%.

[Example 6]
The same procedure as in Example 1 was performed except that the number of moles of copolymerized isophthalic acid was 20 mol%.

[Comparative Example 1]
The same procedure was performed except that isophthalic acid was not used as the sheath component polyester in Example 1.

[Comparative Example 2]
In Example 2, the same procedure was performed except that isophthalic acid was not used as the sheath component polyester.

[Comparative Example 3]
In Example 3, the same procedure was performed except that isophthalic acid was not used as the sheath component polyester.

[Comparative Example 4]
The same procedure as in Example 1 was performed except that the core / sheath area ratio was 40/60.

[Comparative Example 5]
The same procedure as in Example 1 was performed except that the core / sheath area ratio was 97/3.

[Comparative Example 6]
The same procedure as in Example 1 was performed except that the number of moles of isophthalic acid copolymerization was 30 mol%.

[Comparative Example 7]
The same procedure as in Example 1 was carried out except that the number of moles of copolymerized isophthalic acid was 0.3 mol%.

  The present invention relates to a monofilament having a modified surface, and the core-sheath monofilament of the present invention is a high-mesh, high-strength material that requires a high degree of precision, particularly for mesh fabrics for screen printing and the production of printed wiring boards. It is suitable for obtaining a modulus screen.

Claims (3)

A core-sheath type composite polyester monofilament for screen cocoons characterized by satisfying the following AF.
A. The sheath side polyester is a copolymerized polyester obtained by copolymerizing the third component in an amount of 0.5 to 25 mol% with respect to the polyester total acid component and / or the total diol component.
B. The monofilament has a maximum yarn 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 0.03 to 0.14.
F. The core-sheath area ratio of the cross section orthogonal to the fiber axis is 50:50 to 95: 5.   The core sheath type for a screen bag according to claim 1, wherein the third component is at least one selected from the group consisting of isophthalic acid, neopentyl glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, and propylene oxide adduct of bisphenol A. Composite polyester monofilament.   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 strength deterioration (C) obtained by = (A−B) / A × 100 is 0 to 1%, The core-sheath type composite polyester monofilament for a screen bag according to claim 1.