JP3429702B2 - Polyester monofilament for screen gauze - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a monofilament for screen gauze. More specifically, it relates to a polyester monofilament suitable for a high mesh screen gauze required for precision screen printing.

[0002]

2. Description of the Related Art Silk screens for printing have long been made of silk, stainless steel, or the like. In recent years, mesh fabrics made of synthetic fibers have been widely used because of their flexibility and excellent cost performance. Among them, polyester monofilament is excellent in water resistance and dimensional stability and can be said to be most suitable for screen gauze.

However, in the recent printing field such as electronic circuit printing, the demand for precise printing accuracy has become more and more strict, and the screen gauze has a finer fineness and a high breaking strength filament in the direction of high mesh weaving. It is progressing. However, as the fineness becomes finer, the breaking strength of the yarn decreases and the yarn breakage during weaving increases. Further, if the breaking strength is small, it is not possible to stick the cloth with sufficient tension when the cloth is stretched, so that it is not possible to obtain a screen cloth having good weavability.

On the other hand, it is difficult to weave a high-mesh screen gauze with only a high breaking strength,
It is necessary to increase the breaking strength as well as have flexibility. The knot strength is closely related to the flexibility of this fiber, and the smaller the knot strength, the weaker it becomes to bend. As a result, the surface of the monofilament is scraped off by abrasion with a reed during weaving, and a whiskers or powdery scum is apt to occur. However, generally, as the breaking strength increases, the knot strength decreases, and it is preferable to increase the strength of these two kinds as much as possible.

Further, the breaking elongation of the monofilament for screen gauze is preferably 15 to 30% in terms of quality. But,
If high strength is to be obtained, a low elongation yarn will be obtained because it must be drawn at a higher draw ratio in order to achieve high orientation in the drawing process. As a result, it becomes a rigid monofilament, and the surface of the filament is scraped off by the reed at the time of weaving, and whiskers or powdery scum is easily generated. The generated scum stains the loom and impairs workability. At the same time, if a part of the scum is woven into the screen gauze, it becomes a printing defect during precision printing.

Therefore, many improvement techniques have been proposed so far for the purpose of obtaining high strength while maintaining an appropriate elongation. For example, JP-A-5-162476 proposes a core-sheath type composite monofilament having a breaking strength of 6 g / d or more, a breaking elongation of less than 35% and less scum generation. However, the monofilament cannot improve the adhesiveness of the photosensitive resin, which is necessary for screen printing, and furthermore, scum cannot be completely prevented.

Further, JP-A-62-176048 proposes a composite monofilament having a core of polyester and a sheath of a polymer such as nylon which is not easily shaved. By using nylon, it is possible to obtain a monofilament having high flexibility and capable of preventing scum generation. However, the dimensional stability is insufficient due to the high hygroscopicity of nylon, and the field of screen application is limited due to the low chemical resistance of nylon.

[0008]

DISCLOSURE OF THE INVENTION According to the present invention, the adhesiveness of the photosensitive resin is good, and further, because of its high strength, it has good stretchability, and since it can prevent scum generation due to its moderate flexibility, it has good weavability. An object is to provide a monofilament for a high mesh screen gauze.

[0009]

The object of the present invention is a core-sheath composite type polyester monofilament for screen gauze, wherein the core component has an intrinsic viscosity (hereinafter referred to as [η]).
A high-viscosity polyester of 0.66 to 0.90, a sheath component is a polyester obtained by copolymerizing 2 to 15 mol% of naphthalenedicarboxylic acid, and 2 to 6 wt% of a polyalkylene oxide having a number average molecular weight of 300 to 1000, and a core: This can be achieved by using a polyester monofilament for a screen gauze characterized in that the area ratio of the sheath is in the range of 60:40 to 90:10.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The present invention provides a high-density screen (25
A fineness monofilament of 9 to 20 d is used to obtain (0 to 400 mesh). What is required of this monofilament for high-density screen gauze is high breaking strength, adhesiveness to photosensitive resin, and abrasion resistance to the reed of a loom.

In order to obtain a high breaking strength, it is generally necessary for a monofilament for a screen gauze to wind a yarn in a low orientation state by melt-spinning and then draw it at a high ratio in order to make it highly oriented. Become. However, when trying to obtain a monofilament with high breaking strength, it becomes a low elongation yarn,
It becomes weak against shearing and scraping. As a result, when the high mesh screen is woven, the degree of abrasion by the reed is increased, the filament surface is scraped off, and whiskers or powdery scum is easily generated. It is an important subject for obtaining a good screen to simultaneously satisfy the two requirements of high breaking strength retention and abrasion resistance of the high mesh screen weaving.

The appropriate breaking strength of the obtained monofilament is preferably 6.5 g / d or more, and particularly preferably 6.8 g / d or more. When it is 6.5 g / d or more, it can be attached to the gauze frame with sufficient tension, so that yarn breakage is reduced and a screen gauze with good weavability can be obtained.

The suitable breaking elongation of the obtained monofilament is 15 to 15 in terms of processability and quality of the screen gauze.
30% is preferable, and 20 to 25% is particularly preferable.
Within this range, bending while maintaining high breaking strength,
Since it becomes a monofilament that is strong against shearing, it is possible to obtain a screen gauze having a good tightness. If it is less than 15%, scum generation during weaving increases and the stretchability also decreases, which is not preferable. On the other hand, if the elongation is more than 30%, the breaking strength is lowered, and the weavability becomes poor due to yarn breakage, which is not preferable.

In the process of weaving a high mesh screen gauze, the warp threads are repeatedly subjected to extremely fast abrasion of several hundred strokes / minute of reed. Therefore, higher breaking strength is required to prevent yarn breakage. At the same time, the thickness at the intersection with the weft is about twice the fiber diameter, so that the fibers are rubbed while being bent at very minute intervals. That is, it is difficult to weave a high-mesh screen gauze with only a high breaking strength, and in order to improve the weavability, the breaking strength is increased to prevent yarn breakage, and at the same time, the abrasion resistance of the monofilament is increased. It is also preferable to have flexibility in order to enhance the property. As a parameter indicating the brittleness and flexibility due to such bending, the knot strength is used as disclosed in JP-A-4-100914.

The knot strength of the monofilament for screen gauze is closely related to the brittleness of the fiber, and the smaller the knot strength, the weaker the fiber is to bend and the more brittle the fiber. Nodule strength is 5.0
It is preferably at least g / d, and most preferably at least 5.5 g / d. When the knot strength is 5.0 g / d or more, a highly flexible monofilament is obtained, so that the surface is hardly scraped off even by rubbing with a reed, and the weavability is improved.

In the present invention, a core-sheath composite type monofilament composed of two kinds of polymers having different physical properties can be obtained to obtain a monofilament having high breaking strength and good adhesiveness to a photosensitive resin and capable of preventing scum generation. did it. Polyester terephthalate (PE
Examples thereof include aromatic polyesters such as T), polybutylene terephthalate (PBT) and polyethylene naphthalate (PEN), or aliphatic polyesters such as polyethylene succinate and polycaprolactone. Among them, PET is particularly preferably used from the viewpoints of operability during melt spinning and manufacturing cost competitiveness.

In the polyester of the core component used in the present invention, a polymer having a high viscosity range of 0.66 to 0.90 with respect to [η], particularly preferably, in order to obtain a filament strength of 6.5 g / d or more, Polyethylene terephthalate having [η] = 0.68 to 0.85 is used. Within this range, extrusion can be performed with an optimum melt viscosity during melt spinning, and a monofilament with high breaking strength can be obtained. If [η] is less than 0.66, filament strength of 6.5 g / d or more cannot be obtained due to insufficient melt viscosity. On the other hand, when [η] = 0.90 is exceeded, it is difficult to extrude by melt spinning because the melt viscosity is too high, which is not preferable.

As the sheath component of the present invention, a polyester obtained by copolymerizing a specific dicarboxylic acid component for the purpose of increasing the breaking strength and a specific glycol component for the purpose of improving the adhesiveness of the photosensitive resin and the ink permeability is used. As the main component of the sheath polymer, PET is particularly preferably used from the viewpoints of affinity with the core component, production cost and the like.

Although there are many kinds of dicarboxylic acid components to be copolymerized, naphthalene dicarboxylic acid is selectively used in the present invention. Also, although there are many isomers of naphthalenedicarboxylic acid, from the viewpoint of productivity and quality,
6-naphthalenedicarboxylic acid is particularly preferably used. The copolymerization amount is 2 to 1 with respect to the acid component of polyester.
It is 5 mol%, particularly preferably 8 to 12 mol%.
Within this range, the polymer does not become an amorphous polymer, and the effect of improving the breaking strength is large. If less than 2 mol%,
The effect of improving the breaking strength becomes insufficient. On the other hand, 15 mol%
When it exceeds the above range, it becomes an amorphous polymer, and the spinning and drawability of the monofilament is greatly reduced, which is not preferable.

Although there are many kinds of glycol components to be copolymerized, polyalkylene oxide is selectively used in the present invention. Examples of the polyalkylene oxide include polyethylene oxide and polypropylene oxide. Among them, polyethylene oxide is most preferably used. The number average molecular weight of the polyalkylene oxide has an appropriate range, and is 300 to 10
It must be 00. Within this range, the randomness of copolymerization of the polymer is optimized, so that the generation of scum is reduced, and further, there is no scattering outside the polymerization system due to the low boiling point, and the control of the polymerization process is facilitated. When the number average molecular weight is less than 300, the polymerization reaction rate is lowered, and further, the boiling point is lowered to cause scattering outside the polymerization system, resulting in difficulty in controlling the predetermined amount of copolymerization. Further, if the number average molecular weight exceeds 1,000, the randomness of copolymerization of the polymer is deteriorated and scum is generated, which is not preferable.

The copolymerization amount of polyalkylene oxide is 2 to 6% by weight, particularly preferably 3% by weight based on the polymer.
~ 4% by weight. Within this range, heat deterioration of the polyalkylene oxide can be reduced, and appropriate flexibility and strength can be imparted to the monofilament. If the amount is less than 2% by weight, the adhesiveness of the photosensitive resin is significantly reduced, and due to lack of flexibility, a large amount of scum is generated due to rubbing with the reed, and the weavability is degraded. If it exceeds 6% by weight, it becomes excessively flexible and it is not possible to stretch with sufficient tension, which is not preferable.

The polyester of the core component used in the present invention is
It can be obtained by a conventionally known polymerization method. For example, in the case of polyethylene terephthalate, there is a DMT method starting from the transesterification reaction of dimethyl terephthalate, or a direct polymerization method starting from the pressure esterification of terephthalic acid, and either may be used.

Copolymerization of the polyester for the sheath can also be obtained by a conventionally known polymerization method. As a method, first, esterification of terephthalic acid and naphthalenedicarboxylic acid is carried out.
The polyalkylene oxide is preferably added at the time when the above transesterification is completed in order to prevent deterioration due to high temperature. After that, a polycondensation reaction is performed.

The core and sheath polyesters of the present invention include known antioxidants, light stabilizers, antistatic agents, various metal compound catalysts used in polyester production, and various inert particles such as titanium oxide. You may mix silicon oxide, calcium carbonate, etc.

The composite monofilament of the present invention can be obtained by a conventionally known composite spinning method. The cross-sectional shape of the sheath of the composite monofilament in the present invention is not particularly limited, but a circular shape is optimal. The shape of the core component is also not particularly limited, but it is preferable that it is not exposed to the filament surface layer. From the viewpoint of the dimensional stability of the screen after tensioning, the shape and arrangement of the core is optimally a single circle concentric with the sheath.

The core: sheath area ratio has an appropriate range in relation to the filament strength, the resistance to abrasion due to the reed at the time of weaving, and the core: sheath = 60: 40 to 90:10. It is necessary, and particularly in the range of 70:30 to 80:20. When the ratio of the sheath component is within the above range, the thin skin portion is not subjected to frictional damage, and high monofilament strength can be obtained while providing optimum photosensitive resin adhesiveness.
If the ratio of the sheath component exceeds the above range, the filament strength will be insufficient, while if it falls below the above range, the thin skin portion will be damaged by friction due to uneven thickness, or the adhesiveness of the photosensitive resin will be deteriorated.

[0027]

EXAMPLES The present invention will be described in more detail with reference to the following examples. The evaluations in the examples were according to the following methods.

A. Intrinsic viscosity: Intrinsic viscosity is phenol / 1,1,2,2-tetrachloroethane = 6: 4 in solvent
(Weight ratio) was used to measure in a constant temperature bath at 20 ° C.

B. Breaking strength / elongation: According to JIS-L-1013, using an AGS-1KNG autograph tensile tester manufactured by Shimadzu Corporation, the sample was elongated under the conditions of a sample yarn length of 20 cm and a constant tension speed of 20 cm / min. The strength and elongation at break were determined.

C. Knot strength: Measured according to JIS-L-1070.

D. Photosensitive resin adhesion: 0.2 × of diazo resin type photosensitive resin on woven 300 mesh screen gauze
After applying 0.2mm dots at a pitch of 0.2mm to a thickness of 20µm and after proper exposure, Scotch Mending Tape # 81
The tape was peeled by rubbing 0 against 10 reciprocations, and the adhesiveness was evaluated by the amount of resin transferred to the tape. The case where there was substantially no resin transfer was judged as ⊚, the case where there was a slight transfer was judged as ◯, and the case where the transfer was severe to some extent in practical use was judged as x.

E. Weaving property evaluation (scum, yarn breakage): A high mesh screen woven fabric of 300 mesh was woven at a rotation speed of 300 rpm with a through-saw type loom, and the weaving property was evaluated from scum stains on the reed and warp or weft breakage. The yarn breakage was evaluated as good when the weaving length was 500 m or more, and as bad when the weaving length was less than 500 m.

<Polyester Polymerization Method> The polyester used this time was according to the conventionally known DMT method. That is,
Using DMT and ethylene glycol, 0.09 (wt% / ester) of calcium acetate monohydrate and 0.03 (wt% / wt) of manganese acetate tetrahydrate as transesterification catalysts.
Ester) and transesterification was carried out at 235 ° C. When copolymerizing naphthalenedicarboxylic acid, dimethyl naphthalenedicarboxylic acid (hereinafter referred to as 2,6-NDC
M) was added together with DMT to cause a transesterification reaction.
When PEG was copolymerized, it was added after completion of the transesterification reaction and stirred for 10 minutes. In the polycondensation reaction, 0.04 (wt% / polymer) of antimony trioxide was added as a polymerization catalyst, and 0.043 (wt%) of trimethyl phosphate was added as a heat stabilizer, and the polymerization temperature was 280 ° C. and high vacuum of 1.0 torr or less. The polyester chips were obtained under the conditions. The obtained chip was subjected to solid phase polymerization or the like as necessary, and adjusted to have a predetermined [η].

<Spinning Method of Monofilament> According to a conventionally known composite spinning method, a spinning spinneret having an orifice diameter of φ0.35 was used to spin a core-sheath composite monofilament at a spinning temperature of 295 ° C. and a winding speed of 1500 m / min. About 1 day after winding the obtained undrawn filament monofilament, the speed was 500 m / min, the roller heater was 85 ° C., and
It was stretched by passing through a 50 ° C plate heater. The drawn yarn at that time was adjusted so that the breaking elongation was 22 ± 1% and the fineness was 12 ± 0.5d.

<Monofilament Evaluation Test by Changing [η] of Core Component PET> According to the above-mentioned polymerization method, PET having [η] shown in Table 1 as a core component, 12 mol% 2,6-NDCM as a sheath component, A copolymerized PET was obtained with polyethylene glycol having a molecular weight of 600 (hereinafter PEG # 600) being 4% by weight. Using these, the core-sheath area ratio was set to 70:30, and spinning was performed according to the above-described spinning method to obtain a core-sheath composite monofilament. Table 1 shows the results of evaluation of the yarn quality and weavability of this monofilament.

[0036]

[Table 1]

In Comparative Example 1 (Experiment No. 1), since the melt viscosity was low, yarn breakage occurred frequently and the weavability was poor. Further, in Comparative Example 2 (Experiment No. 4), the melt viscosity was too high, so the spinnability was poor, and spinning was extremely difficult. On the other hand, Examples 1 and 2 according to the present invention (Experiment Nos. 2 and 3)
Since it maintains high breaking strength, there is no thread breakage,
The weavability was good.

<Monofilament Evaluation Test in Change of Core-Sheath Area Ratio> According to the above-mentioned polymerization method, PET of [η] = 0.66 as a core component and 2,6-N as a sheath component.
DCM 12 mol%, PEG # 600 4 wt%
As a result, copolymerized PET was obtained. Using these, according to the above-described spinning method, the core-sheath area ratio was variously changed as shown in Table 2 to obtain a core-sheath composite monofilament. Table 2 shows the results of evaluation of the yarn quality and weavability of this monofilament.

[0039]

[Table 2]

In Comparative Example 3 (Experiment No. 5), since the core area ratio was small, the breaking strength was low and many yarn breakages occurred. In Comparative Example 4 (Experiment No. 7), although the breaking strength was high, the sheath area ratio was too small and the sheath layer partly broke, resulting in scum generation, and the weavability was poor. On the other hand, in Examples 1 and 3 (Experiment Nos. 2 and 6) according to the present invention, the core-sheath maintained the optimum thickness, so that the breaking strength was high and the weavability was good.

<Monofilament Evaluation Test in Changing Composition of Copolymerization Component> According to the above-mentioned polymerization method, PET having [η] = 0.66 as a core component and PET containing a copolymerization composition as shown in Table 3 as a sheath component. Got Using these, the core-sheath area ratio was set to 70:30, and spinning was performed according to the above-described spinning method to obtain a core-sheath composite monofilament. Table 3 shows the results of evaluating the yarn quality and weavability of this monofilament.

[0042]

[Table 3]

Comparative Example 5 (Experiment No. 8) is a homo-PET monofilament that is not polymer-modified, but this has poor adhesiveness to the photosensitive resin, and weavability as a high-mesh screen gauze due to the generation of a large amount of scum. Was bad. Further, Comparative Example 6 (Experiment No. 9) was 2, 6
Since the mol% of -NDCM was too low, the effect of improving the breaking strength was low, resulting in frequent yarn breakage. Comparative Example 7 (Experiment No. 1)
In 4), since the mol% of 2,6-NDCM was too high, it became a rigid filament, which led to the generation of a large amount of scum. Comparative Example 8 (Experiment No. 15) was PEG # 600.
However, since the amount of addition of the compound was small, the adhesiveness to the photosensitive resin was poor, resulting in a filament having high breaking strength and low knot strength, which led to the generation of a large amount of scum. Comparative Example 9 (Experiment N
o. In the case of 16), since the amount of PEG # 600 added was too large and it became too soft, the knot strength increased but the breaking strength decreased, and the weaving property deteriorated.

On the other hand, Examples 1, 4 to 7 according to the present invention
In (Experiment No. 2, 10 to 13), 2,6-NDCM was used.
The rupture strength increased as the molar ratio was increased. Although the knot strength tended to decrease, the knot strength was maintained at 5.0 g / d or higher in all cases. Also, the adhesiveness to the photosensitive resin was better than that of the comparative example. The occurrence of scum was smaller in all the examples than in the comparative examples, and the weavability was good.

<Monofilament Evaluation Test for Change in Number Average Molecular Weight of PEG> According to the above-mentioned polymerization method, PET of [η] = 0.66 as a core component, 12 mol% of 2,6-NDCM as a sheath component and 4 wt% of PEG. % Copolymerized PET was obtained. At this time, the number average molecular weight of PEG was variously changed as shown in Table 4. Using these, the core-sheath area ratio was set to 70:30, and spinning was performed according to the above-described spinning method to obtain a core-sheath composite monofilament. Table 4 shows the results of evaluation of the yarn quality and weavability of this monofilament.

[0046]

[Table 4]

In Comparative Example 10 (Experiment No. 17), although the breaking strength was high, the adhesiveness of the photosensitive resin and the weaving property were poor due to the lack of the degree of polymer modification. In Comparative Example 11 (Experiment No. 19), excessive wetting of the polymer resulted in excessive softening, and a large amount of scum was generated, resulting in poor weavability. On the other hand, Examples 1 and 8 according to the present invention (Experiment No.
Nos. 2 and 18) had good adhesiveness to the photosensitive resin and good weavability.

[0048]

The core-sheath type composite monofilament made of the polyester of the present invention uses a copolyester which gives excellent physical properties as a sheath component and a polyester which gives excellent mechanical properties such as high breaking strength of the monofilament as a core component. Therefore, it is possible to supply a screen gauze having excellent adhesiveness to the photosensitive resin, good stretchability and abrasion resistance, and excellent weavability.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeki Honda 4-1, Kanebocho, Hofu-shi, Yamaguchi Kanebo Synthetic Fibers Co., Ltd. (56) Reference JP-A-5-125638 (JP, A) JP-A-5- 51868 (JP, A) JP-A-2-289120 (JP, A) JP-A-4-307294 (JP, A) JP-A-58-98426 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) D01F 8/14 B41N 1/24

Claims (3)

(57) [Claims] 1. A core-sheath composite type monofilament, wherein the core component is a high-viscosity polyester having an intrinsic viscosity of 0.66 to 0.90, and the sheath component is naphthalene dicarboxylic acid from 2 to 15.
It is a polyester obtained by copolymerizing 2% to 6% by weight of polyalkylene oxide having a mol% and a number average molecular weight of 300 to 1000, and having a core: sheath area ratio of 60: 40-9.
A polyester monofilament for a screen gauze, which is in the range of 0:10. 2. The polyester monofilament for a screen gauze according to claim 1, wherein the single yarn denier is in the range of 9 to 20 d. 3. The monofilament for a screen gauze according to claim 1, which has a breaking elongation of 15 to 30%, a breaking strength of 6.5 g / d or more and a knot strength of 5.0 g / d or more.