JP4870619B2 - Core-sheath monofilament for screens - Google Patents

Description

  The present invention relates to a monofilament suitable for obtaining 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.

  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 this monofilament are becoming strict, and improvements such as adhesion to rubber, fatigue resistance, dyeability, abrasion resistance, and knot strength are being urged. Especially in the recent printing in the electronic circuit field, the degree of integration is increasing, and due to the printing density as a screen flaw, there is a strong demand for high mesh, high modulus and improved printability, especially dimensional stability in continuous printing. It has become.

  According to Patent Document 1 for designing screen yarns, a polyester core-sheath monofilament, a core having a high modulus and high strength polyester, a sheath having a specific Tg polyester, and a breaking strength or breaking as a monofilament It has been proposed to use a specific value for the modulus at elongation and elongation of 10% to make the screen wrinkle with high strength, high modulus and less thread shaving during weaving. When passing through the wet heat setting and tensioning process, the yarn shrinks and the load curve of the yarn becomes different from that before shrinkage, so the dimensional stability as a screen wrinkle is poor and there is a problem in continuous printability. there were.

In addition, the screen wrinkle is used for printing through a process of coating an emulsion on the surface after weaving, and exposing and curing the emulsion to copy the electronic circuit. When halation of the irradiated light occurs when the emulsion is exposed and cured, printing accuracy is deteriorated. Therefore, the occurrence of halation is reduced by dyeing after weaving. However, if the dyeability of the fiber is poor, there are problems such as using a large amount of dye, requiring special equipment such as high-temperature and high-pressure dyeing, and thus damaging the fiber.
Therefore, there has been a demand for the development of monofilaments for screen wrinkles that are suitable for screen wrinkles that are excellent in dimensional stability and that have good dyeability and that can be dyed even at low temperatures.
JP-A-2-289120

  The present invention provides a core-sheath composite fiber monofilament for screen wrinkles that is easily dyeable and excellent in dimensional stability.

  By defining a core-sheath type composite fiber monofilament made of polyester obtained by copolymerizing polyethylene naphthalate as a core component and isophthalic acid or bisphenol A as a sheath component in a specific amount, by defining the strength and elongation characteristics before and after wet heat treatment, dimensional stability and A monofilament for screen wrinkles with improved low-temperature dyeability can be obtained.

Thus, the present invention is achieved by a screen sheath core-sheath composite polyester monofilament that satisfies the following A to I.
A. Monofilament maximum strength before wet heat treatment of 5.5 to 8.0 cN / dtex, strength at 5% elongation of 3.8 to 5.5 cN / dtex, maximum elongation of 8 to 20%, wet heat The shrinkage rate is 0.5 to 4.0%.
B. Monofilament has a maximum yarn strength after wet heat treatment of 5.0 to 7.8 cN / dtex, a strength at 15% elongation of 4.5 to 7.0 cN / dtex, and a maximum elongation of 15 to 30%. thing.
C. The main component of the core side polyester is polyethylene naphthalate as a main component, and the core side intrinsic viscosity is 0.50 to 0.80 dL / g.
D. The sheath side polyester is a polyethylene terephthalate copolymer obtained by copolymerizing 5 to 25 mol% of isophthalic acid or bisphenol A with respect to the total acid component.
E. The intrinsic viscosity of the sheath side polyester is 0.40 to 0.65 dL / g.
F. The birefringence of the sheath side polyester is 140 × 10 ^{−3 to} 170 × 10 ⁻³ .
G. The core-sheath area ratio of the cross section orthogonal to the fiber axis is 30:70 to 90:10.
H. The single yarn fineness is 4 to 24 dtex.
I. The number of knots is 1.1 or more times the fiber diameter in the monofilament longitudinal direction of 500,000 meters.

  As a monofilament for screen wrinkles with dimensional stability and easy dyeability, it is useful for precision electronic circuit screen printing.

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 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. , Consisting of 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 the maximum point strength before wet heat treatment of the monofilament (simply called strength) 5.5 to 8.0 cN / dtex, the strength at 5% elongation is 3.8 to 5.5 cN / dtex, and the maximum point elongation (sometimes referred to simply as elongation) is 8. -20%, wet heat shrinkage ratio is 0.5-4.0%, maximum point strength after wet heat treatment is 5.0-7.8 cN / dtex, strength at 15% elongation (modulus, 15% below) ASE) is 4.5 to 7.0 cN / dtex and the maximum point elongation is 15 to 30%, so that it becomes highly dimensional stable after the process of texture adjustment, wet heat setting and tensioning as a screen ridge. It can be an excellent screen jar. The maximum point strength and elongation mean strength and elongation at the time of cutting in the unloading curve of the raw yarn.
The fineness is preferably 4 to 24 dtex. If it is less than 4 dtex, the strength is insufficient, and if it exceeds 24 dtex, it is not preferable because the mesh is not high.

  The monofilament for screen wrinkles of the present invention uses 0.5 to 0.8 dL / g of high IV polyethylene naphthalate for the core side polyester and 0.40 to 0.65 dL / g of isophthalic acid or bisphenol A for the sheath side polyester. Using a polyethylene terephthalate copolymer obtained by copolymerizing 5 to 25 mol% of the total acid component, a core-sheath monofilament is obtained using a normal composite spinning apparatus. 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 90:10. When the core ratio is lower than 30, the effect of the core component cannot be exhibited and the dimensional stability is lacking. On the other hand, when the core ratio exceeds 90, a portion that is not covered with the sheath component may be generated, and it is not preferable because scraping due to wrinkles occurs during weaving.

  By setting the IV of the polyethylene naphthalate at the core to 0.5 to 0.8, it is possible to obtain a high strength and high modulus, a high modulus, high mesh screen wrinkle and good dimensional stability. can do. Here, when IV is lower than 0.5, the strength is lowered and the high modulus cannot be obtained, and when it exceeds 0.8, the melt viscosity is too high and the spinnability is lowered, which is not preferable.

  As the polyester of the sheath, it is necessary to make a polyester having an IV of 0.40 to 0.65 obtained by copolymerizing 5 to 25 mol% of isophthalic acid or bisphenol A with respect to the total acid component, and the IV is 0.4. If it is less than 40, the strength is lowered, and if it exceeds 0.65, thread shaving due to wrinkles increases, which is not preferable.

The birefringence of the sheath side polyester needs to be 140 × 10 ^{−3 to} 170 × 10 ⁻³ . If it is less than 140 × 10 ^−3, it is difficult to obtain the target strength with the raw yarn before and after boiling water treatment, and if it exceeds 170 × 10 ⁻³ , shavings adhere to the reeds during weaving and deteriorate the weaving performance. This is not preferable.
When the sheath is configured as described above, yarn shaving due to wrinkles at the time of weaving can be reduced and low-temperature dyeability can be achieved. It is preferable for making a screen wrinkle with little damage and good dimensional stability.

As the physical properties of the core-sheath type composite fiber monofilament of the present invention, the maximum point strength before wet heat treatment is 5.5 to 8.0 cN / dtex, 5% LASE is 3.8 to 5.5 cN / dtex, and the maximum point elongation is The reason why it is necessary to design 8 to 20% and wet heat shrinkage to 0.5 to 4.0% will be described.
Higher 5% ASE is preferable, but if it exceeds 5.5 cN / dtex, it is not preferable because scraping due to wrinkles occurs during weaving, and it is woven into the woven fabric, resulting in defects. On the contrary, if it is less than 3.8 cN / dtex, the elongation of the screen wrinkles becomes large, which is not preferable.

If the maximum point strength is less than 5.5 cN / dtex, the screen wrinkle strength is insufficient and breakage is likely to occur during tensioning, and if it exceeds 8.0 cN / dtex, the shrinkage rate is difficult to remove, and scoring due to wrinkles occurs during weaving. It becomes easy to do.
On the other hand, when the maximum point elongation is less than 8%, the yarn handling property is deteriorated, for example, the weaving yarn breakage occurs frequently. If the maximum point elongation is 20% or more, wrinkle elongation tends to occur.

The wet heat shrinkage rate is preferably in the range of 0.5 to 4.0%. Outside this range, 15% LASE after the wet heat treatment cannot be within a specific range, which is not preferable. (Based on the correlation between the 15% LASE of the yarn after the wet heat treatment and the dimensional stability of the screen wrinkle after the wet heat treatment, the 15% LASE after the wet heat treatment of the monofilament of the present invention is 4.5-7. 0.0 cN / dtex)
Although the specific manufacturing method for obtaining the monofilament of this characteristic is demonstrated, it is not necessarily limited to this.

  The monofilament of the present invention can be obtained by melt spinning the above-described polyethylene naphthalate and polyethylene terephthalate copolymer into a core-sheath monofilament using a composite spinneret, followed by stretching. 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 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. 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 before wet heat treatment, elongation, wet heat shrinkage, strength after wet heat treatment, elongation, strength at 15% elongation, evaluation of the number of nodes, evaluation of thread scraping, evaluation of hysteresis Was performed with the following definition.

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 before wet heat treatment, 5% ASE:
The strength and elongation of the fiber are the strength and elongation when the sample is broken according to JIS-L1017, measured using a Tensilon manufactured by Orientec Corporation at a sample length of 25 cm and an elongation rate of 30 cm / min.
5% LASE measured the stress when the sample at the time of the above measurement was extended by 5%.

Moist 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.

Strength after wet heat treatment, elongation, 15% ASE:
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 at a sample length of 25 cm and an elongation rate of 30 cm / min using Tensilon manufactured by Orientec Co., Ltd. . For 15% ASE, the stress was measured when the sample at the time of the above measurement was extended 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.

Dyeing evaluation:
The drawn yarn is made into a tubular knitted or woven form, dyed amber with disperse dyes in the usual manner, and the normal dyeing at 100 ° C. gives the highest dyeing level at 5 points and the lightest dyeing level at 1 point. Staining evaluation was performed at each stage.

[Example 1]
Polyethylene naphthalate with an intrinsic viscosity of 0.68 dL / g is used on the core side, and polyethylene terephthalate with an intrinsic viscosity of 0.62 dL / g copolymerized with 2.0 mol% of isophthalic acid is used on the sheath side. At a temperature of The intrinsic viscosity on the core side sampled 2 hours after the start of discharge was 0.61 dL / g, and the intrinsic viscosity on the sheath side was 0.54 dL / g. While being wound at a spinning speed of 700 m / min, an unstretched yarn was obtained while attaching an oil agent with an oiling roller. Then, after preheating with a hot roller heated at 145 ° C., while being heated at 200 ° C. with a slit heater, it was stretched at 5.0 times, subjected to a relaxation treatment of 0.03 times, wound up, and stretched at 13 dtex-1 fill. I got a thread. The obtained drawn yarn has a strength of 6.1 cN / dtex, an elongation of 16%, a 5% ASE of 4.4 cN / dtex, a wet heat shrinkage of 3.0%, a strength after boiling water treatment of 6.0 cN / dtex, and an elongation of 18 %, 15% LASE was 5.4 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. The obtained woven fabric was low-temperature dyed at 100 ° C. by a known method. Staining points were 5 points. The hysteresis evaluation for the screen was ◯. When continuously printed using a screen wrinkle, the elongation was small and the dimensional stability was excellent.

[Comparative Example 1]
In Example 1, polyethylene terephthalate having an intrinsic viscosity of 0.85 dL / g was used on the core side, the intrinsic viscosity on the core side sampled 2 hours after the start of discharge was 0.74 dL / g, and the intrinsic viscosity on the sheath side was 0.00. It was 53 dL / g. While being wound at a spinning speed of 700 m / min, an unstretched yarn was obtained while attaching an oil agent with an oiling roller. Then, after preheating with a hot roller heated at 150 ° C., the film was stretched by 4.2 times while being heated at 200 ° C. with a slit heater, subjected to a relaxation treatment of 0.05 times, wound up, and stretched by 13 dtex-1 file. I got a thread. The obtained drawn yarn had a strength of 6.1 cN / dtex, an elongation of 25%, a 5% ASE of 4.0 cN / dtex, a wet heat shrinkage of 8.0%, and a strength after boiling water treatment of 6.0 cN / dtex. The elongations of 35% and 15% ASE were 3.5 cN / dtex, and a high modulus could not be maintained after wet heat treatment.

[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 240 ° C. The obtained drawn yarn has a strength of 6.1 cN / dtex, an elongation of 16%, a 5% ASE of 4.3 cN / dtex, a wet heat shrinkage of 2.5%, a strength after boiling water treatment of 6.1 cN / dtex, and an elongation of 20 %, 15% LASE was 5.6 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. The obtained woven fabric was low-temperature dyed at 100 ° C. by a known method. Staining points were 5 points. The hysteresis evaluation for the screen was ◯. When continuously printed using a screen wrinkle, the elongation was small and the dimensional stability was excellent.

[Comparative Example 2]
In Example 1, a drawn yarn was obtained in the same manner as in Example 1 except that polyethylene terephthalate not copolymerized with isophthalic acid was used on the sheath side. The obtained drawn yarn had a strength of 6.1 cN / dtex, an elongation of 16%, a 5% ASE of 4.3 cN / dtex, a wet heat shrinkage of 2.7%, a strength after boiling water treatment of 6.0 cN / dtex, and an elongation of 18 %, 15% LASE was 5.5 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. However, the dyeing point of 3 points and the target deep dyeability could not be obtained, and there was a problem in easy dyeability.

  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 screen cocoons characterized by satisfying the following A to I.
A. Monofilament maximum strength before wet heat treatment of 5.5 to 8.0 cN / dtex, strength at 5% elongation of 3.8 to 5.5 cN / dtex, maximum elongation of 8 to 20%, wet heat The shrinkage rate is 0.5 to 4.0%.
B. The monofilament maximum strength after wet heat treatment is 5.0 to 7.8 cN / dtex, the strength at 15% elongation is 4.5 to 7.0 cN / dtex, and the maximum elongation is 15 to 30%. thing.
C. The main component of the core side polyester is polyethylene naphthalate as a main component, and the core side intrinsic viscosity is 0.50 to 0.80 dL / g.
D. The sheath side polyester is a polyethylene terephthalate copolymer polyester obtained by copolymerizing 5 to 25 mol% of isophthalic acid or bisphenol A with respect to the acid component.
E. The intrinsic viscosity of the sheath side polyester is 0.40 to 0.65 dL / g.
F. The birefringence of the sheath side polyester is 140 × 10 ^{−3 to} 170 × 10 ⁻³ .
G. The core-sheath area ratio of the cross section orthogonal to the fiber axis is 30:70 to 90:10.
H. The single yarn fineness is 4 to 24 dtex.
I. The number of knots is 1.1 or more times the fiber diameter in the monofilament longitudinal direction of 500,000 meters.   When the original yarn after the wet heat treatment is stretched by 7%, the load is applied as an initial load, and when the 1.5% continuous elongation is further performed 1000 times, the load (B) is compared with the 30th load (A), C = The core-sheath type composite monofilament for screen wrinkles according to claim 1, wherein the strength deterioration (C) obtained by (AB) / Ax100 is 0 to 1%.