JPH02242971A - Polyester monofilament for screen gauze - Google Patents

Abstract

PURPOSE:To obtain the subject polyester monofilament forming only small amount of white powder scum in the weaving of gauze and having excellent dimensional stability by applying a specific surface-treatment agent to a polyester monofilament having specific fiber characteristics. CONSTITUTION:A polyester monofilament for the production of a high-quality screen gauze having an elongation at break of 30-50% and a tensile stress (g/d) at 10% elongation of <=3.25 is produced by spinning a polyester polymer having an intrinsic viscosity maintained to 0.7-1.0 and oiling the spun filament in the course of either drawing or warping process with a treatment agent containing >=50wt.% of a monobasic acid monoester derived from a monohydric aliphatic alcohol and a monobasic aliphatic carboxlylic acid. The generation of white powder scum in the weaving of a gauze can be suppressed by the application of the above surface treatment and the obtained gauze has excellent quality fit in the use as a screen plate for the printing of a high density and high quality IC substrate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a polyester monofilament for screen gauze, and more specifically, to efficiently produce screen gauze of excellent quality with less generation of white powder scum during weaving. This invention relates to a polyester monofilament that can be used as a polyester monofilament.

[Prior art] Polyester monofilament, especially polyethylene terephthalate monofilament, has many excellent properties and has traditionally been used for screen gauze.In recent years, it has also entered the fields of electronics and high-end printing, and monofilament thin There are increasing demands for greater fineness, higher strength, and durability.

However, when weaving screen gauze using this polyester monofilament, white powder scum is likely to occur and cause various problems.

Problems caused by the generation of white powder scum are particularly common when weaving high-density screen gauze of 260 mesh or more using polyester monofilament with a fineness of 20 denier or less as warp threads.This white powder scum is caused by repeated abrasion of the reed. When using polyester monofilament with a fineness of more than 20 denier, the reed width (the gap between the reeds and the cross-sectional diameter of the filament) is wide, so the degree of abrasion is light and the effect is small. Because of the large amount of white powder scum generated, there is little actual damage to the gray fabric.

However, when polyester monofilament with a fineness of 20 deniers or less is used, the reed gap is usually smaller than the filament diameter, so the filament is repeatedly subjected to strong abrasion, resulting in significant surface damage and white powder scum.

Therefore, this white powder scum clogging causes warp thread breakage and warp streak spots on the gray fabric, resulting in a significant deterioration in both quality and production efficiency.

In order to solve this problem, the elongation at break is 30 to 60%.
It is known from JP-A-55-16948 that it is effective to use a polyester monofilament. However, although this polyester monofilament is effective in preventing the generation of white powder scum, since it uses a high elongation monofilament, the strength of the monofilament inevitably decreases, and it is elongated by rubbing under high tension during screen gauze weaving. There are problems in that the gauze tends to have warp streaks, its tensile strength is low, and its dimensional stability is reduced.

In order to solve this problem, the present inventors previously proposed a monofilament made of polyester with a specific intrinsic viscosity and having specific strength and elongation characteristics (Japanese Patent Application No. 63-277
No. 074), the gauze made of this polyester monofilament certainly reduces the generation of white powder scum during weaving, and improves the quality of the gauze. However, there are still some aspects that are insufficient for use as a screen original plate for even higher-grade screen printing such as printing of high-grade IC boards.

[Problems to be Solved by the Present Invention] The present invention was developed in view of the above problems, and it produces less white powder scum during screen gauze weaving, has high tensile strength, excellent dimensional stability, and improves the warp of gauze. The purpose of the present invention is to provide a polyester monofilament for use in high-grade screen gauze, which is suitable for producing high-density screen gauze with good quality and less generation of streaks.

[Means for Solving the Problems] As a result of intensive studies to achieve the above object, the present inventors finally achieved the desired result by applying a specific surface treatment agent to a polyester monofilament having specific fiber properties. The present inventors have discovered that the quality of the screen gauze produced is greatly improved and have arrived at the present invention.

That is, according to the present invention, the monofilament made of polyester is a monofilament that simultaneously satisfies the following C (i) to (d), and the monofilament has a monobasic acid ester with a molecular weight of 300 to 500 on the surface of the monofilament in a proportion of 50 to 50% of the active ingredient. There is provided a polyester monofilament for screen gauze, which is characterized in that a processing agent containing at least % by weight is attached thereto.

(A) 0.7≦Intrinsic viscosity≦1.0 (B) 35≦Elongation at break (%)≦50 (C) 5.0≦Strength at break (g/de) f=+ 3.
Tensile strength at elongation of 25≦10% (r/de) The polyester monofilament of the present invention is primarily a monofilament made of polyethylene terephthalate.

However, it may also be a polyester in which ethylene terephthalate is the main repeating unit, and a small proportion (usually 20 mol % or less) of a third component other than the terephthalic acid and ethylene glycol components is copolymerized and/or mixed.

This monofilament may be melt-spun and drawn as a multifilament and then split, or it may be melt-spun and drawn as a monofilament from the beginning.

The polyester monofilament of the present invention has a fineness of 20
The effect is remarkable when targeting monofilaments of denier or less. Those with a fineness of more than 20 denier not only generate less white powder scum, but are also used for relatively low mesh, and are often used for applications that do not require high precision printing, and are difficult to maintain the dimensional stability of gauze. Gender is not required.

However, although the present invention is particularly effective for monofilaments with a fineness of 20 deniers or less, it goes without saying that monofilaments with a fineness of more than 20 deniers may also have the characteristics defined in the present invention.

The monofilament of the present invention has an intrinsic viscosity of 0.7 to
It is necessary to be within the range of 1.0. Intrinsic viscosity is 0
．． If it is less than 7, it will be difficult to achieve the high strength and high elongation physical properties of the present invention, and it will also be difficult to reduce white powder scum during gauze weaving under high tension. On the other hand, if the intrinsic viscosity exceeds 1.0, the intrinsic viscosity of the polyester polymer used during melt spinning must normally exceed 1.2 (i.e., because the polymer decomposes due to heat and moisture during melting, The intrinsic viscosity of the polymer must be higher than that of the thread)
Melt spinning becomes difficult.

Here, the value of the intrinsic viscosity is measured in a 0-talolophenol solution at 25°C.

Further, as shown in FIG. 1(A), the monofilament of the present invention needs to have high strength, high elongation, and high tensile strength at 10% elongation.

FIG. 1 shows the strength and elongation curves of polyester monofilaments, in which (A) is the polyester monofilament of the present invention, and (B) is the conventional polyester monofilament. (C) is a conventional polyester monofilament that generates a large amount of white powder scum.
Although it is effective against white powder scum, it is a polyester monofilament with poor dimensional stability. In addition, in FIG. 1, E! is the elongation at break, (d)m is the elongation at 10%, st is the tensile strength at break, and st- is the tensile strength at 10% elongation.

The elongation at break of the polyester monofilament of the present invention is
It is necessary that it is 35-50%, preferably 40-50%. Here, if the elongation at break is less than 35%, the scum reduction effect during weaving is insufficient, if it exceeds 35%, the white powder scum reduction effect increases, and in the range of 40 to 60%, the scum reduction effect is maximum. becomes.

On the other hand, in the monofilament having a breaking elongation of more than 50%, it is difficult to increase the tensile strength in a short period of time, and the dimensional stability is poor.

Thus, the elongation at break of polyester monofilament that can achieve the object of the present invention is 35 to 50%.

Further, the polyester monofilament of the present invention needs to have a tensile strength of 5.0 g/de or more, and a tensile strength at 10% elongation of 3.2 g/de or more. Here, the elongation at break is 5. Less than or/de, the tensile strength at 10% elongation is 3.25 g/de Monofilament with groove at the end has a small tensile strength, so it may be partially weak in parts due to abrasion under high tension by the reed during gauze weaving. There is a problem in that some parts of the gauze undergo greater elongation than others, causing the gauze's transmuscular rings and sagging, resulting in a decline in the quality of the gauze.

On the other hand, the elongation at break is 5. A polyester monofilament having a tensile strength of 3.25 g/do or more and a tensile strength at 10% elongation of 3.25 g/do or more can effectively solve such problems and produce gauze with improved quality.

In the present invention, it is not enough to keep the physical properties of the monofilament within the above range, and a treatment agent containing 50% by weight or more of a monobasic acid ester with a molecular weight of 300 to 500 based on the active ingredient on the surface of the monofilament is used. The biggest feature is that it is attached.

The term "basic acid ester" as used herein refers to a monoester compound obtained from a small amount of aliphatic alcohol and a monovalent aliphatic carboxylic acid, and has a molecular weight of 300 to 500, preferably 350 to 450. . Examples of such basic acid esters include octyl palmitate, octyl stearate lauryl laurate, 2-ethylhexyl stearate, isotridecyl palmitate, isostearyl capricate, and the like.

In the present invention, it is important that the molecular weight of the -basic acid ester is 500 or less; if it exceeds 500, the friction between the running yarn and the weaving machine yarn guide will increase and the generation of white powder scum will increase. Unfavorable, on the other hand, 30
If it is less than 0, it will volatilize due to the heat of the drawing V1 floor during spinning and produce smoke, causing a problem of contamination of the working environment.In addition, polybasic acid esters with divalent or higher valences may cause the generation of white powder scum. This is not desirable because the suppressing effect is small and the object of the present invention cannot be achieved.

At that point, monobasic acid esters with a molecular weight of 300-500 are
Since the friction between the traveling yarn and the yarn guide during weaving is small and the yarn guide has sufficient smoothness, it is extremely effective in reducing the generation of white powder scum, and there are fewer troubles in the monofilament manufacturing process.

Further, the proportion of the above-mentioned -basic acid ester in the active ingredients of the processing agent must be 50% by weight or more. If it is less than this range, the smoothness is insufficient, which tends to increase the generation of white powder scum during weaving, and also tends to increase troubles in the monofilament manufacturing process, which is not preferable.

The processing agent used in the present invention may include other smoothing agents, such as mineral oil with a viscosity of 90 to 170'' and monobasic acid esters and dibasic acid esters having a molecular weight of more than 500, within a range that does not impair the purpose of the present invention. Tribasic acid esters, etc., or emulsifiers, such as POE alkyl ethers.

It goes without saying that POB polyhydric alcohol esters, etc., as well as oil film strengthening agents, antistatic agents, etc., may be added.Also, if the amount attached to the thread is too small, fluff may occur due to lack of smoothness. ,l! There is a problem with IF thread generation,
On the other hand, if the amount is too high, scum formation tends to increase, so it is desirable to keep the amount in the range of 0.1 to 0.4% by weight.

The method for producing the polynisder monofilament of the present invention includes determining the intrinsic viscosity of the polyester to be subjected to melt spinning,
It can be obtained by appropriately adjusting melt spinning conditions and stretching heat treatment conditions and applying a treatment agent in the form of an emulsion during a normal spinning process.

For example, while spinning and heating the area directly below the yarn nozzle to approximately 300℃,
Polyester with If1 limiting viscosity of 0.8 to 1.2 from 295 to
The undrawn yarn is melted and discharged at a temperature of 300° C., then the discharged yarn is cooled and solidified, and taken off at a speed of 600 to 900 m/min while applying the treatment agent in an amount of 0.1 to 0.4% by weight, and then the obtained undrawn yarn is When stretching 3.4 to 4.5 times, 95 to
High temperature preheating stretching at 115°C and further stretching at 150°C under stretching tension.
It is obtained by high-temperature heat treatment at ~180°C and winding at a stretching speed of 600-800 m/min.

Here, in order to obtain a polyester monofilament having the physical properties of the present invention, it is important to use a polyester whose intrinsic viscosity is larger than the usual 0.65, preferably 0.75 or more, and to Intrinsic viscosity 0.7~
1.0, and after spinning at low speed, high-magnification, high-temperature stretching, and high-temperature heat treatment, high breaking strength, high 10% offshore long strength, and high breaking elongation can be simultaneously achieved. . That is, in order to improve the strength properties, it is common to stretch at a high magnification, but it is difficult to simultaneously improve the elongation properties.Therefore, in this polyester monofilament manufacturing method, the normal stretching temperature is 85 to 95%.
By setting the temperature higher than that of °C, stretching is performed while relaxing local distortions in the internal structure due to stretching. Thereby, stress concentration during local elongation can be suppressed, and elongation characteristics can be improved. Furthermore, since high-magnification stretching is also possible at the same time, it is possible to improve the breaking strength and the strength characteristics at 10% elongation. Furthermore, the normal heat treatment temperature 14
By developing the crystal structure by performing high-temperature heat treatment at 150-180°C compared to 5-150°C,
It is possible to improve strength characteristics.

It goes without saying that the treatment agent can be applied in the form of an emulsion or straight during or before or after each step of stretching and warping.

[Example] Hereinafter, the present invention will be described in more detail with reference to Examples.

In addition, the strength and elongation in the examples are those of Instron TM-M type (
This is the strength elongation on the stress-strain curve measured with a filament length of 201
, stretch speed 100%/min, temperature and humidity 20℃ x 65%
This is the average value of strength and elongation obtained by repeatedly measuring each burn five times for arbitrary ten burns under RH conditions.

Example 1 Polyethylene tele and phthalate polymers were used, melted so that the polymer temperature at the time of discharge was 295°C, and discharged from a nozzle with a pore diameter of 0.65 ni to a predetermined fineness after stretching. The oil shown in Table 1 was added to the yarn weight ratio of 0.3.
% and was once wound up at a take-up speed of 800 rri/min. Next, it was stretched at various magnifications, and as shown in Table 2, it had a denier of 16, an intrinsic viscosity of 0.80, and an elongation at break of 30 to 50. %, breaking strength is 5.1 to 5.8 g/de
, Tensile strength at 10% offshore length is 3.25 to 4.2 g/de
Various polyester monofilaments were obtained.

These monofilaments were rubbed under the following conditions and the amount of white powder scum generated was compared, and the results are also shown in Table 2.

In the abrasion test, a monofilament with a length of 20 m was hooked 30 times in parallel on two gripping rods facing each other at a spacing of 30 mm, fixed under a tension of 3 g, and this monofilament was placed in the center. The sample was passed through a sliding rubbing reed (made of stainless steel) and rubbed at a speed of 400 times/minute for 120 minutes, and the amount of scum attached to the monofilament was observed and graded into the following 3H floor.

◎: Almost no white powder scum is generated.

O: Few white powder scum moths.

△: Slightly more white powder scum.

X: There is a lot of white powder scum.

Further, the obtained monofilament was partially warped to have a warp number of 10.177, and the same monofilament as the warp was used as the weft to weave 300 meshes of screen gauze at a speed of 180 times/min using an ordinary loom. . The weaving results are also shown in Table 2.

Here, gauze quality A reversal rate refers to warp breakage due to white powder scum clogging, warp streak spots on gray fabric, warp streaks due to reed scratches during weaving, etc.
It is judged based on scores such as looseness, etc., and a score lower than a predetermined score is called an A reversal rate, which indicates a pass rate, and 92% or more is considered an acceptable line.

The preheating temperature during stretching was 105°C, and the heat treatment temperature was 17°C.
A high temperature heat treatment at 0° C. was performed to obtain a monofilament with predetermined physical properties.

As shown in Table 2, the monofilament of the present invention (second
In the table, Experiment NQ2-4.7, 10. il, 14)
It can be seen that it is an excellent product with extremely little white powder scum and extremely good gauze quality.

Example 2 In the same manner as in Example 1, the treatment agent shown in Table 3 was applied at a yarn weight ratio of 0.3% by weight, and as shown in Table 4. 9-2
2 denier, intrinsic viscosity 0.65-0.90. Breaking elongation is 30-53%, breaking strength is 4.8-5.8 g/d
e.

Various polyester monofilaments having a tensile strength at 10% elongation of 3.25 to 4.2 g/da were obtained.

These monofilaments were evaluated in the same manner as in Example 1 for the amount of white powder scum generated and the gauze grade A reversal rate.

In Table 4, Examples 1IQi to 17 were subjected to high-temperature heat treatment at a preheating temperature of 105°C and a heat treatment temperature of 170°C during stretching to obtain monofilaments with predetermined physical properties. Furthermore, in Experiments NG18 to NG21, stretching was carried out at a preheating temperature of 90°C and a heat treatment temperature of 145°C, and monofilaments having the physical properties shown in Table 4 were obtained.

As shown in Table 4, the monofilament of the present invention (Table 4)
In the table, test samples 4 to 12 and 16 to 17) had good white powder scum and good gauze quality, indicating that the monofilaments of the present invention were excellent.

[Effects of the Invention] The screen gauze made of polyester monofilament for screen gauze of the present invention has extremely low generation of white powder scum during weaving, has excellent gauze quality, and can be used as a high-quality screen original plate for printing IC boards made of high-density screen gauze. Can be used.

[Brief explanation of drawings]

Fig. 1 is a strength/elongation curve of a polyester monofilament, in which (A) is an example of the polyester monofilament of the present invention, and (B> and (C) are examples of conventional polyester monofilaments. E! indicates elongation at break, (d) Trout indicates 10% elongation, st indicates breaking strength, and Stm indicates tensile strength at 10% elongation.

Claims (1)

[Claims] The monofilament made of polyester is the following (a) -
A monofilament that satisfies (d) at the same time, characterized in that a processing agent containing 50% by weight or more of a monobasic acid ester with a molecular weight of 300 to 500 based on the active ingredient is attached to the surface of the monofilament. Polyester monofilament for screen gauze. (B) 0.1≦Intrinsic viscosity≦1.0 (B) 35≦Elongation at break (%)≦50 (C) 5.0≦Strength at break (f/de) (D) 3.25≦10% elongation tensile strength (g/de)