JP2003213527A - Polyester monofilament for screen gauze and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester monofilament for screen gauze having high strength and modulus, excellent dimensional stability and scum-suppressing effect unattainable by conventional monofilaments, enabling the formation of fine-denier product and suitable for a precision printing. <P>SOLUTION: The polyester monofilament for screen gauze is a core-sheath conjugate monofilament composed of a polyethylene terephthalate as the core and the sheath components, satisfying the formula X-Y≥0.25 (X is the intrinsic viscosity IV of the polymer of the core component; and Y is the intrinsic viscosity IV of the polymer of the sheath component) and having a breaking strength of ≥6.5 cN/dtex. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for screen-printing mesh fabrics, and more specifically, for obtaining a high-mesh, high-modulus screen mesh fabric for high precision printing, which is excellent in dimensional stability. The present invention relates to a polyester monofilament, which has a good effect and a scum suppressing effect, has a high strength and a high modulus, and can be applied to fine denier.

[0002]

2. Description of the Related Art As a screen woven fabric for printing, a mesh woven fabric made of natural fibers such as silk and inorganic fibers such as stainless steel has been widely used, but recently, it has flexibility and durability and has a size. Mesh fabrics made of organic fibers such as nylon and polyester, which are also stable, that is, screen gauze are increasingly used. Of these, screen gauze fabrics made of polyester monofilaments are widely used because they are less affected by moisture than those made of nylon and are advantageous in terms of price.

However, in recent years in the field of printing electronic circuits for home electric appliances, the demand for improvement in printing accuracy has become stricter, and therefore the mesh is finer and the dimensional stability with less elongation is excellent when it is used for tight-fitting. Screen gauze has been requested. That is, a fine denier, high strength, and high modulus are required for the raw yarn for screen gauze.

In general, in order to increase the strength and modulus of polyester fiber, it has been known that in the manufacturing process of the raw yarn, the fiber is drawn at a high ratio to have high orientation and high crystallization. Since the manufacturing process involves weaving a high-density woven fabric at a high speed, it is exposed to strong friction such as reed a very large number of times. Or powder dust, so-called scum, is likely to occur,
This phenomenon tends to be more severe with higher crystallization. Even if the scum is small in quantity, there is a risk that the scum will be scattered on the loom and a part of the scum will be taken into the screen gauze fabric. In such a case, a high mesh fabric for precision printing may cause a fatal defect such as clogging of the mesh, and prevention of scum is an important issue in the screen gauze.

For this reason, many improvement techniques have been proposed for the purpose of reducing or preventing the occurrence of scum. For example,
In JP-A-55-16948, the elongation at break is 35% to
It has been proposed to use yarns with a high elongation of 60%. However, high elongation means that low-stretching is carried out, which means that it is inevitably low in strength and low in modulus. In other words, the prior art proposed here gives priority to reducing the generation of scum, and therefore sacrifices the characteristics of high strength and high modulus. In this case, the strength is insufficient when fine denier is made in accordance with the demand for high mesh, and not only the weaving property is deteriorated, but also woven fabric stretch and the like cause deterioration of dimensional stability, which is not suitable for precision printing. It will be something like.

Further, Japanese Patent Application Laid-Open No. 1-132829 proposes a core-sheath composite fiber which uses polyester as a core and nylon which is more resistant to abrasion than polyester as a sheath. Certainly, it is known that nylon causes less scraping than polyester, which is advantageous in terms of suppressing scum generation. On the other hand, however, nylon has the drawback of having higher hygroscopicity and lower dimensional stability than polyester. Therefore, the core-sheath composite fiber using nylon as the sheath can reduce the occurrence of scum, but has poor dimensional stability that is essential for precision printing.

At present, screen gauze is used for printing after a process of applying an emulsion after weaving, exposing and curing the emulsion, and copying an electronic circuit. Therefore, if halation of irradiation light occurs when the emulsion is exposed to light and cured, printing accuracy is deteriorated. Therefore, after weaving, dyeing with a light-colored dye is performed to reduce the occurrence of halation.
However, even in the screen gauze after dyeing, it is currently difficult to reduce the printing accuracy due to halation to zero. This is also one of the reasons why it is difficult to perform high-precision printing by using a high mesh.

As described above, according to the conventional technique, the characteristics required for obtaining a screen gauze fabric for precision printing, that is, high strength, high modulus, excellent dimensional stability, small scum generation, and fine denier are supported. No polyester monofilament with possible properties was obtained.

[0009]

DISCLOSURE OF THE INVENTION The present invention has improved the above-mentioned problems and has high strength and modulus, excellent dimensional stability, and scum suppressing effect, which cannot be obtained by conventional monofilaments, and can be applied to fine denier. It is an object of the present invention to provide a polyester monofilament for a screen gauze that is suitable for precision printing.

[0010]

In order to achieve the above-mentioned object, the present invention has the following constitution. That is, in the core-sheath type composite monofilament, when both components of the core-sheath are polyethylene terephthalate, and the intrinsic viscosity (IV) of the polymer of the core component is X and the intrinsic viscosity (IV) of the polymer of the sheath component is Y-Y-Y Satisfies ≧ 0.25,
The polyester monofilament for screen gauze, which has a breaking strength of 6.5 cN / dtex or more, can achieve the above object.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester monofilament of the present invention is a core-sheath type composite monofilament arranged such that the core component is covered with the sheath component and the core component is not exposed on the surface in the cross section. Here, the core-sheath type means that the core component is completely covered with the sheath component, and the core-sheath type is not necessarily arranged concentrically. There are several shapes such as circles, flats, triangles, squares, and pentagons in cross section, but it is easy to obtain stable thread-forming properties and high-order processability, and halation when exposed by applying emulsion after weaving. In order to prevent the occurrence of the above, a circular cross section is preferable in view of the stability of the screen mesh opening.

In the present invention, the fine particles forming the sheath preferably contain inorganic fine particles. Here, the inorganic fine particles specifically include silica sol, silica, alkyl-coated silica, alumina sol, titanium oxide, calcium carbonate, etc., but any inorganic fine particles may be used as long as they are chemically stable when added to polyester. Silica sol, silica, preferably from the viewpoint of chemical stability, cohesiveness and ease of use.
Alkyl-coated silica and titanium oxide are preferable, and titanium oxide is more preferable. When using titanium oxide,
From the viewpoint of dispersibility, the average particle size of titanium oxide is preferably 1 μm or less, more preferably 0.7 μm or less. The maximum particle size is preferably 5 μm or less, more preferably 3 μm or less, from the viewpoint of spinnability.

By including the inorganic fine particles, the friction coefficient of the surface of the monofilament becomes small, and the effect of suppressing scum generated by rubbing at the time of weaving can be obtained. Therefore, it is desirable that the friction coefficient of the surface of the monofilament be 0.40 or less (friction against mirror surface metal), so the content is preferably 0.05% or more. On the other hand, the upper limit of the content is set by the spinnability. When the content is 1.0% by mass or less, the spinnability is good, the rate of increase in filtration pressure in the spinning step is suppressed, and the pack replacement cycle in the spinning step becomes long, which is preferable.

The polyester monofilament for screen gauze is a high-strength monofilament suitable for precision printing, and the higher the breaking strength, the lower the weavability and the occurrence of gall elongation and the like, and the higher dimensional stability can be obtained. The polyester monofilament for screen gauze of the present invention has a high IV.
By using the above polymer as a core component, it is possible to increase the strength and obtain a high strength fiber having a breaking strength of 6.5 cN / dtex or more. At this time, the elongation at break is 10 to 30%, and the modulus at 10% elongation (hereinafter 10% Mo) is 70 to 70% of the breaking strength.
It is preferably 100%. As a result, it is possible to prevent the surface-crystallinity of the core-sheath composite type monofilament from becoming unnecessarily high, suppress the amount of scum generated during weaving, and obtain high dimensional stability.

In the present invention, both core-sheath components are polyethylene terephthalate, and the polymer IV difference must be 0.25 or more. High IV with IV difference of 0.25 or more
In the case of a polymer, the stretching ratio can be set low in order to obtain a breaking strength of 6.5 cN / dtex or more, which means that the orientation of the sheath component polymer is suppressed, the crystallinity of the monofilament surface is lowered, and the occurrence of scum is suppressed. To do. Therefore, the ability to stretch at a low magnification suppresses the orientation of the sheath component polymer, and is very effective in suppressing scum. Preferably IV
The difference is 0.45 or more.

In the present invention, since both the core component and the sheath component are polyester, the phenomenon of peeling at the composite interface, which often occurs in polyester / nylon composite yarns, is unlikely to occur. However, by adjusting the weight composite ratio of the core component to the sheath component to be 95: 5 to 70:30, it is possible to prevent a part of the core from being exposed on the surface and causing a decrease in the scum suppressing effect due to the sheath component, and to reduce the skin. It is preferable to do so because the amount of the polymer of the core component having a higher IV is increased so that higher strength can be achieved. This effect becomes more preferable by setting the weight composite ratio of the core component to the sheath component to be 90:10 to 75:25.

The manufacturing method for obtaining the core-sheath type composite monofilament of the present invention can be manufactured by utilizing the following composite spinning technology. Polymers that form the core and sheath components are independently melted, weighed, and filtered, then combined using a spinneret to form a core-sheath composite yarn, combined, discharged from the same discharge port, and heated under the spinneret. It is obtained by being heated by a cylinder and then cooled. A drawing process is required to increase the strength, but a method of obtaining a high-strength drawn yarn through a drawing process after winding once as an undrawn yarn, or a method of directly drawing after spinning without winding And any method such as a method for obtaining a drawn yarn may be used.

By using a non-woven fabric filter for the polymer filtration layer when spinning the monofilament, the gelled polymer generated in the polymer pipe or pack due to thermal deterioration can be filtered, removed or dispersed. preferable. In polyester spinning, gelled polymer not only causes yarn breakage in spinning process, yarn breakage in drawing process, single yarn winding, etc., but also causes gelled polymer to be mixed into single yarn. This causes a so-called knot, in which the thread thickness is different from other portions. In the monofilament, this causes a decrease in the yarn thickness uniformity related to the uniformity of the opening of the screen, but it can be prevented by filtering / removing or dispersing the gelled polymer using a non-woven fabric filter. . It also has the effect of uniformly dispersing the aggregates of the inorganic fine particles used, and can prevent yarn breakage and deterioration of quality due to aggregation.

Further, it is desirable that the die used for spinning the monofilament has two or more ejection holes, and all the ejection holes are arranged at the same distance from the center of the die. Generally, the polymer discharge amount of monofilament is smaller than that of multifilament,
Therefore, the residence time of the polymer in the spinning machine tends to be long. As a result, the phenomenon that the gelation of the polymer progresses due to the above-mentioned thermal deterioration is observed. For this reason, 2 discharge holes
By using a die having more than one die, the amount of polymer discharged per die can be increased and the residence time of the polymer can be shortened, so that generation of gelled polymer due to thermal deterioration can be suppressed. Further, since the IV decrease due to heat can be suppressed at the same time, the strength decrease of the monofilament can also be prevented. The residence time of the polymer can be shortened by using such a die and increasing the discharge amount, but it is not only the polymer and the die that are subject to thermal history until the polymer is discharged from the die after melting. Time becomes a problem. Therefore, in order to suppress IV reduction and gelation, the passage time from melting to discharge from the die is 60 min. It is more preferable that it is within the range.

In addition, by using a die in which the polymer discharge holes are also arranged at the same distance from the die center,
This is preferable because the dispersibility of the polymer into each discharge hole and the temperature history of the spinneret can be the same for all discharge holes, and the uniformity of the thread thickness required as a monofilament for screen gauze can be obtained.

The heating cylinder installed under the base is 200 to 40
The temperature is appropriately set within the range of 0 ° C. The discharged fibers are gradually cooled by the heating cylinder, and the elongation of the obtained undrawn yarn becomes high. Therefore, even if the draw ratio is 4 times or more, a drawn yarn having a residual elongation of 10 to 30% can be obtained after drawing. The length of the heating cylinder is determined by the high IV polymer and is not particularly limited. However, if the length is too long, the thickness unevenness of the fiber remarkably appears, so that the length is preferably 70 cm or less.

The manufacturing method is not particularly limited as long as it is a method capable of obtaining the core-sheath type composite monofilament of the present invention. An example of the manufacturing method is given below. Polyethylene terephthalate was used as the polymer for both the core and sheath components, and these were heated to above the melting point and melted to give a spinning temperature of 290
At ˜300 ° C., the core component is compounded and discharged from the same die so that the sheath component is completely covered. This is heated in a heating cylinder, gradually cooled and solidified, and then 500 to 1500 m / mi
n. To wind an undrawn yarn. 80 to 22
The core-sheath composite yarn of the present invention can be obtained by drawing at a draw ratio of 4.0 times or more using two or three hot rollers heated to 0 ° C.

[0023]

EXAMPLES The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Each measured value in the examples is a value measured and determined by the following method.

A. Dimensional stability Observe the distortion of the print pattern due to the dimensional instability when printing 1000 sheets, and indicate that there is no distortion, ○, that there is some distortion but there is no problem in quality, △, that there is distortion and there is a problem in quality. It was judged.

B. Scum generation degree judgment Through the loom is used and the rotation speed of the loom is 350 rpm.
As a weaving mesh fabric. At that time, visually observe the dirt on the reed to check the condition of scum adhesion and the condition of scatter around. Then, the weaving length at the time when it was judged that the weaving could not be continued any more was used as the evaluation value. That is, the shorter the length, the more the occurrence of scum. As an evaluation, 500 m or more is ◯, less than 500 m is 300.
A value of m or more was evaluated as Δ.

Example 1 Polyethylene terephthalate having different levels of IV difference was used as a core / sheath component polymer, and these were individually heated to a temperature equal to or higher than the melting point and melted, and at a spinning temperature of 298 ° C., discharge holes were formed from the center of the spinneret. Weight composite ratio (core: sheath) so that the core component is completely covered by the sheath component from the four discharge holes located at a distance.
At 82:18, they are compounded and discharged. This is length 20c
After heating to 300 ° C in a heating cylinder of m, gradually cooling and solidifying, 10
00 m / min. To wind an undrawn yarn. Using a pair of hot rollers heated to 90 ° C. and 150 ° C., the stretching ratio was variously changed and the breaking strength, breaking elongation, and 10% MO were changed to obtain the levels shown in Table 1.

In Experiments 1 and 5, since the breaking strength did not reach a sufficient level, weavability was poor and dimensional stability was poor.

Experiments 2 to 4, 6 and 8 are examples, and since the IV difference is at a sufficient level, both the breaking strength and the breaking elongation are good. At the same time, the amount of scum generated is small and good. In particular, in Experiments 3 and 4, breaking strength, breaking elongation, 10% MO
Both are extremely good.

Experiment 7 is a comparative example, and there was a problem in dimensional stability because the elongation was high and a sufficient level of breaking strength was not obtained.

Experiments 9 and 10 are also comparative examples. Since the IV difference was not sufficient, the breaking strength did not satisfy the target value, and the dimensional stability was inferior in some cases.

[0031]

[Table 1] Example 2 By changing the weight composite ratio of the core-sheath composite fibers, the IV difference was 0.4.
No. 9, the yarn was made in the same manner as in Example 1, and the breaking strength and the amount of scum generated during weaving at this time were evaluated. Further, the spinning was performed under the condition that the addition amount of the inorganic fine particles was changed, and the inorganic fine particles and the spinnability were evaluated.

12 to 16 are examples. As the core component increases in the weight composite ratio, the breaking strength increases and reaches the target level. 11 is a comparative example. The weight composite ratio was lower than 70:30, and the target strength could not be obtained. Furthermore, there were problems in the spinnability and the amount of scum generated when titanium oxide was added to the inorganic fine particles and when titanium oxide was not added. In Experiment 14 in which the addition amount was 1.0% by weight, the spinnability was slightly inferior.

[0033]

[Table 2]

[0034]

The polyester monofilament obtained in the present invention has high strength and modulus which are not obtained by the conventional monofilament, excellent dimensional stability, and scum suppressing effect, and can be applied to finer denier.
This polyester monofilament can be used for screen gauze, making use of its excellent dimensional stability, high strength, and high modulus, and can be made into a high-mesh necessary for precision printing on electronic substrates, etc. Since it is possible to stabilize the weaving process of screen gauze and improve its quality, it is a material suitable as a raw yarn for screen gauze.

Continued front page    F-term (reference) 2H114 AB04 DA56 EA02 FA02                 4L041 AA07 AA20 BA02 BA05 BA21                       BA46 BC20 BD14 BD20 CA06                       CB05 CB25 DD01 DD04 DD21

Claims (5)

[Claims] 1. In a core-sheath type composite monofilament, when both components of the core-sheath are polyethylene terephthalate, and the intrinsic viscosity (IV) of the polymer of the core component is X and the intrinsic viscosity (IV) of the polymer of the sheath component is Y. A polyester monofilament for a screen gauze, which satisfies XY ≧ 0.25 and has a breaking strength of 6.5 cN / dtex or more. 2. The polyester monofilament for a screen gauze according to claim 1, wherein the breaking elongation is 10 to 30%, and the modulus at 10% elongation is 70 to 100% of the breaking strength. 3. A core-sheath weight composite ratio of 70:30 to 95: 5.
The polyester monofilament for a screen gauze according to claim 1 or 2, wherein 4. A core-sheath type composite fiber comprising a sheath component containing 1.0% by weight or less of inorganic fine particles.
A polyester monofilament for a screen gauze according to any one of 1. 5. In the core-sheath composite spinning, both core-sheath components are polyethylene terephthalate, the intrinsic viscosity (IV) of the polymer of the core component is X, and the intrinsic viscosity (I) of the polymer of the sheath component is
When V) is Y, a polymer having a combination satisfying XY ≧ 0.25 is used, and the weight composite ratio of the core and the sheath is 95: 5 to 7
At 0:30, a heating cylinder is installed under the spinneret to perform melt spinning,
Then, a method for producing a polyester monofilament for screen gauze, which is drawn with a hot roller.