JP2001140128A - Polyester monofilament for screen plain gauze - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-strength and high-modulus polyester monofilament fiber of a fine denier for a screen plain gauze having excellent dimensional stability and scum and halation suppressing effects which cannot be obtained by a conventional monofilament fiber and capable of providing a high mesh. SOLUTION: This polyester monofilament for the screen plain gauze is characterized as comprising 0.05-1.0 wt.% of inorganic fine particles in at least a sheath part in a core-sheath type conjugate monofilament comprising a core part which is polyethylene terephthalate and the sheath part that is a copolyester consisting essentially of ethylene terephthalate and having >=5.74 CN/dtex breaking strength, 15.0-30.0% breaking elongation and 4.85-6.18 CN/dtex modulus at 10% elongation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mesh fabric for screen printing, and more particularly, to an excellent dimensional stability suitable for obtaining a high mesh and high modulus screen gauze fabric used for high precision printing. The present invention relates to a polyester monofilament having high strength, high modulus, and capable of coping with fine denier, having properties, scum suppressing effect and halation suppressing effect.

[0002]

2. Description of the Related Art As a screen fabric for printing, a mesh 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 dimension. Mesh fabrics made of organic fibers such as nylon and polyester, which are also stable, that is, screen gauze are increasingly used. Among these, screen gauze fabrics made of polyester monofilaments have been widely used because they are less affected by moisture than those made of nylon and are advantageous in terms of price.

However, in the field of printing of electronic circuits for home appliances in recent years, the demand for improving the printing accuracy has become stricter. Screen gauze is being demanded. In other words, fine denier, high strength, and high modulus are required for the raw yarn for screen gauze.

In general, it is known that in order to increase the strength and modulus of polyester fiber, it is sufficient to draw it at a high magnification in the production process of the raw yarn and to make it highly oriented and highly crystallized. In the manufacturing process, high-density woven fabrics are woven at high speed, so they will be exposed to strong friction such as reeds very many times, and along with the progress of surface crystallization, a part of the filament surface will be scraped off and a mustache, Or powdery scum, so-called scum, tends to occur,
This phenomenon tends to be more severe as the crystallinity increases. Even if the amount of the scum is small, there is a risk that the scum may be scattered on the loom and a part of the scum may be taken into the screen gauze fabric. In such a case, in a high-mesh fabric for precision printing, a fatal defect such as clogging of the mesh may occur, and prevention of scum is an important issue in screen gauze.

[0005] For this reason, many improvement techniques have been proposed for the purpose of reducing and preventing the occurrence of scum. For example,
JP-A-55-16948 discloses that the elongation at break is 35% or less.
It has been proposed to use a high elongation yarn of 60%. However, high elongation means that low-stretching is performed, which necessarily means low strength and low modulus. In other words, the prior art proposed here sacrifices the characteristics of high strength and high modulus because priority is given to reducing the occurrence of scum. In this case, when denier is reduced according to the demand for high mesh, the strength is insufficient, and not only the weaving property is reduced, but also the elongation occurs and the dimensional stability is deteriorated, which is not suitable for precision printing. It will be something.

Japanese Unexamined Patent Publication (Kokai) No. 1-132829 proposes a core-sheath composite fiber using polyester as a core and nylon as a sheath, which is more durable than polyester, against abrasion. Certainly, it is known that nylon generates less shavings than polyester, and is advantageous in terms of suppressing the generation of scum. However, on the other hand, nylon has the disadvantage that it has higher hygroscopicity and lower dimensional stability than polyester. For this reason, in the core-sheath composite fiber using nylon for the sheath, although the generation of scum can be reduced, the dimensional stability which is indispensable for precision printing is poor.

At present, screen gauze is used for printing through a process of copying an electronic circuit by coating an emulsion after weaving, exposing and curing the emulsion. For this reason, when halation of the irradiation light occurs when the emulsion is exposed and cured, the printing accuracy deteriorates. Therefore, after weaving, the fabric is dyed with a light-colored dye to reduce the occurrence of halation.
However, it is difficult at present to reduce the printing accuracy of the screen gauze after dyeing due to halation to zero, and this is one of the causes of the difficulty in high-precision printing by high meshing.

As described above, according to the conventional technology, it is necessary to obtain the screen gauze fabric for precision printing, that is, to cope with fine denier, which has high strength, high modulus, excellent dimensional stability, little scum and little scum. No polyester monofilament with the possible properties was obtained.

[0009]

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

[0010]

SUMMARY OF THE INVENTION The present invention has the following configuration to attain the above-mentioned object. That is, in the present invention, the core is a copolymerized polyester containing polyethylene terephthalate as a main component and the sheath as ethylene terephthalate as a main component, the breaking strength is 5.74 CN / dtex or more, the breaking elongation is 15.0 to 30.0%, A core / sheath composite monofilament having a modulus at 10% elongation of 4.85 to 6.18 CN / dtex, wherein at least the sheath portion contains 0.05 to 1.0% by weight of inorganic fine particles. The above object can be achieved by a polyester monofilament for screen gauze.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester monofilament of the present invention is a core-sheath type composite monofilament in which a core component is covered with a sheath component and its core component is not exposed on the surface in a cross section thereof. Here, the core-sheath type is only required that the core component is completely covered by the sheath component, and it is not always necessary to arrange them concentrically. There are various cross-sectional shapes such as round, flat, triangular, square, and pentagonal.However, it is easy to obtain stable thread formability and high-order workability. In order to suppress the generation of the screen girder, a round cross section is preferable from the viewpoint of the stability of the opening of the screen gauze.

In the present invention, it is necessary that at least the sheath-forming component contains 0.05% to 1.0% by mass of inorganic fine particles. Here, specific examples of the inorganic fine particles include silica sol, silica, alkyl-coated silica, alumina sol, titanium oxide, and calcium carbonate. Any inorganic fine particles may be used as long as they are chemically stable when added to polyester. Silica sol, silica, alkyl-coated silica, and titanium oxide are preferred from the viewpoints of chemical stability, cohesion and ease of use, and titanium oxide is more preferred. When using titanium oxide, the average particle diameter of titanium oxide is preferably 1 μm or less, more preferably 0.7 μm or less from the viewpoint of dispersibility. Further, the maximum particle size is preferably 5 μm or less, more preferably 3 μm or less from the viewpoint of spinning properties.

The content of the inorganic fine particles is 0.05% by mass.
If the amount is smaller, the light reflectance of the inorganic fine particles is reduced, and the effect of preventing halation cannot be sufficiently obtained. Further, the coefficient of friction of the monofilament surface becomes large, and the effect of suppressing scum generated by abrasion during weaving cannot be sufficiently obtained. For this reason, it is desirable that the coefficient of friction of the monofilament surface be 0.40 or less (anti-specular metal friction). On the other hand, if the content exceeds 1.0% by mass, it causes undesired decrease in spinnability, and the rate of increase in filtration pressure in the spinning step becomes too large, and the cycle of pack exchange in the spinning step is undesirably short. Further, the strength of the obtained conjugate fiber is reduced, and in high-order processing, the quality such as fluff and breakage of single yarn is reduced, which is not preferable. In addition, in the weaving process, the wear of healds and reeds is promoted, which is not preferable.

There is no problem in adding inorganic fine particles to the core component depending on the purpose and use. However, in this case, the kind and amount of the inorganic fine particles to be added are 1.0 as in the case of the sheath component. It is preferable that the content is not more than mass%. However, the lower limit of the amount of the inorganic fine particles is not particularly limited and may not be added.

The polyester monofilament of the present invention is a high-strength monofilament suitable for precision printing,
The breaking strength is 5.74 CN / dtex or more. By setting the breaking strength to 5.74 CN / dtex or more, it is possible to suppress a decrease in the weaving property and the occurrence of elongation, and to obtain high dimensional stability. The breaking elongation is 15.0 to 30.0.
%, The modulus at 10% elongation (hereinafter 10% Mo) is 4.
85 to 6.18 CN / dtex. As a result, the surface crystallinity of the core-sheath composite monofilament can be prevented from becoming unnecessarily high, the amount of scum generated during weaving can be suppressed, and high dimensional stability can be obtained.

In the present invention, the color tone (L value) of the composite monofilament is preferably 70 ≦ from the viewpoint of suppressing halation of irradiation light at the time of coating, exposing and curing an emulsion after weaving to prevent deterioration of printing accuracy. It is preferable that L ≦ 80. The color tone (L value) can be adjusted by the catalyst formulation for polymerizing the polymer and the amount of inorganic particles added to the sheath component. By setting the color tone (L value) to 70 or more, a sufficient halation suppression effect can be obtained.

In the present invention, the polyester used for the core component must be polyethylene terephthalate.
Further, the polyester used for the sheath component needs to be a copolymer polyester containing ethylene terephthalate as a main component in order to obtain the effect of lowering the crystallinity of the monofilament surface and suppressing the generation of scum. Examples of suitable copolymers used for forming the copolymerized polyester include isophthalic acid, adipic acid, dicarboxylic acids such as dimer acid, diethylene glycol, low molecular weight glycols such as butanediol, polyethylene glycol, and polytetramethylene glycol. Of these, polyalkylene glycols are preferred, and among these, polyalkylene glycol is preferred in that the fiber-forming property and the effect of suppressing crystallization to sufficiently suppress scum generation can be obtained.

When a polyalkylene glycol is used, its copolymerization amount is preferably 3.0 to 10.0% by weight. By setting the copolymerization amount to 3.0% by weight or more, a sufficient effect of lowering the crystallinity can be obtained, and a sufficient effect of suppressing scraping can be obtained.

In the present invention, since both the core component and the sheath component are made of polyester, the phenomenon of peeling off at the composite interface, which often occurs in polyester / nylon composite yarns, hardly occurs. However, it is preferable to set the composite ratio of the core component: the sheath component to 95: 5 to 70:30, since it is possible to prevent a part of the core from being exposed to the surface, thereby preventing the sheath component from deteriorating the scum suppression effect. This effect is more preferable when the composite ratio of the core component: the sheath component is 90:10 to 75:25.

The production method for obtaining the core-sheath type composite monofilament of the present invention can be produced by utilizing a conventionally known composite spinning technique. That is, it is obtained by melting, weighing, and filtering the polymers forming the core component and the sheath component independently, then combining and combining them into a core-sheath composite yarn using a die, and discharging them from the same discharge hole.
Note that a drawing step is required to increase the strength.However, a method of obtaining a high-strength drawn yarn through a drawing step after winding once as an undrawn yarn, or directly drawing without spinning after spinning And any method such as a method of obtaining a drawn yarn may be used.

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

Furthermore, it is desirable that a spinneret used for spinning a monofilament has two or more discharge holes, and all of the discharge holes are arranged at the same distance from the center of the spinneret. Generally, the polymer discharge amount of monofilament is smaller than that of multifilament,
Therefore, the polymer residence time in the spinning machine tends to be long. As a result, a phenomenon is seen in which the gelation of the polymer due to the thermal degradation proceeds. Therefore, the number of discharge holes is 2
By using a die having more than one piece, the amount of polymer discharged per die can be increased and the polymer residence time can be shortened, so that the generation of gelled polymer due to thermal degradation can be suppressed. In addition, since a decrease in IV due to heat can be suppressed at the same time, a decrease in strength of the monofilament can also be prevented. The retention time of the polymer can be shortened by using such a base and increasing the discharge amount.However, the polymer receives heat history not only in the pack, but also in the base part until the polymer is melted and discharged from the base. Time becomes a problem. Therefore, in order to suppress the IV reduction and gelation, the passage time from melting to discharge from the die is 60 min. More preferably, it is within the range.

In addition, by using a base in which the polymer discharge holes are arranged at the same distance from the center of the base,
Since the distribution property of the polymer to each of the discharge holes and the temperature history of the die can be the same for each of the discharge holes, it is preferable because the uniformity of the thread thickness required for the monofilament for screen gauze can be obtained.

The production method is not particularly limited as long as it is a method capable of obtaining the core-sheath composite monofilament of the present invention. The following is an example of the production method. Polyethylene terephthalate is used as the polymer for the core component, and copolymerized polyethylene terephthalate in which 5 to 9% by weight of polyethylene glycol is copolymerized is used as the polymer for the sheath component.
The composite is discharged from the same die at ３００300 ° C. so that the core component is completely covered by the sheath component. After cooling and solidifying this, 900 to 1200 m / min. To obtain an undrawn yarn. This was stretched to 4.0 using a pair of hot rollers heated to 90 ° C. and 150 ° C.
The core-sheath composite yarn of the present invention can be obtained by stretching at a ratio of at least twice.

[0025]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In addition, each measured value in an Example and a comparative example is a value measured and judged by the following method. A. Judgment of scum generation degree Using a sluser loom and setting the rotation speed of the loom to 350 rpm
Weave a mesh fabric. At this time, dirt on the reed is visually observed to check the adhesion of scum and the scattering to the surroundings. Then, the weaving length at the time when it was judged that weaving could no longer be continued was used as the evaluation value. That is, the shorter the weaving length, the more scum is generated. B. Color (L value) The L value of the obtained drawn yarn (bobbin) was measured with a SM-4 color computer manufactured by Suga Test Instruments. C. Composite ratio A filament to be evaluated is collected, and a cross section is enlarged to an arbitrary magnification using a microscope according to the discharge amount of the core component and the sheath component polymer, and photographed. Using this photograph, the composite ratio is determined from the cross-sectional area ratio of the core component and the sheath component. Example 1 and Comparative Example 1 Polyethylene terephthalate was used as a core component polymer.
7.5 of polyethylene glycol as a sheath component polymer
% By weight of copolymerized polyethylene terephthalate to which 0.30% by weight of titanium oxide has been added.
Then, from the four discharge holes whose discharge holes are at the same distance from the center of the base, the composite is discharged at a compound ratio of 80:20 so that the core component is completely covered by the sheath component. After cooling and solidifying this, 1000 m / min. To obtain an undrawn yarn. This was drawn at a draw ratio of 4.3 times using a pair of hot rollers heated to 90 ° C. and 150 ° C. to obtain a core-sheath composite monofilament having a fineness of 8 dtex.

In the same manner, yarns were prepared by changing the amount and type of the copolymer component and by changing the amount and type of the inorganic fine particles, and evaluated for the occurrence of scum, the effect of suppressing halation, and the yarn forming property. (Experiment No. 3).

Experiment No. 2, 3, 4, 6, 7, 8, 9,
Samples Nos. 10 and 11 were the present invention, and the scum generation was small, the halation was suppressed, and the spinning property was good at any level. The experiment N
o. As compared with Experiment No. 3, In the case of Experiment No. 6, the halation suppression effect was slightly inferior. 7, 8
In the cases of Nos. 9 and 9, the amount of scum generated tended to be slightly large. Experiment No. As for No. 11, a tendency that the yarn formability was slightly poor was observed.

Experiment No. In the case of No. 1, since the addition amount of the inorganic fine particles was 0, the effect of suppressing halation was low and there was a problem in printing accuracy. Experiment No. In No. 5, the amount of the inorganic fine particles added was large, and a reduction in the spinning property and a reduction in the yarn strength were observed.

[0029]

[Table 1] Example 2 Example 1, experiment no. Table 2 shows that, when a core-sheath composite monofilament having a fineness of 8 dtex was produced using the same polymer as in Example 3 and having a fineness of 8 dtex, the stretching ratio was variously changed to change the breaking strength, breaking elongation, and 10% Mo. I got the standard. In addition, those with a changed composite ratio of core and sheath,
A polymer whose color tone (L value) was changed by adjusting the polymerization catalyst formulation or the amount of inorganic particles added was obtained. Thereafter, the scum generation state, dimensional stability, and halation generation state were evaluated in the same manner as in Example 1 using these.

Experiment No. Examples 12 to 22 are examples. With respect to 14, 15, 19 and 21, scum was less generated compared to other levels, dimensional stability and halation were good, and high printing accuracy was obtained.

[0031]

[Table 2] Example 3 Example 1, experiment no. When a core-sheath composite monofilament having a fineness of 8 dtex is manufactured using the same polymer as that of No. 3 and a core-sheath composite monofilament having a fineness of 8 dtex, a non-woven fabric filter is used for the polymer filtration layer using a die having a different number of discharge holes and discharge hole arrangement. A yarn was prepared by preparing a material which was not used and a material which was not used, and the levels shown in Table 3 were obtained. At this time, the evaluation of the yarn-making properties, the yarn strength of the obtained monofilament, and the occurrence of knots was performed.

Experiment No. Examples 31 to 36 are examples. In Nos. 31 and 32, the yarn-making properties were better than other levels, no knots were observed, and the desired yarn strength was obtained.

[0033]

[Table 3]

[0034]

The polyester monofilament obtained in the present invention has excellent dimensional stability, scum suppression effect, and halation suppression effect which cannot be obtained by the conventional monofilament, and has high strength, high modulus and fine denier. Can respond to. This polyester monofilament can be used for screen gauze, making use of its excellent dimensional stability, high strength, and high modulus properties to make a high mesh required for precision printing such as electronic substrates.
Since the scum suppressing effect and the halation suppressing effect can stabilize the weaving process of the screen gauze and improve the quality, it is a material suitable as a raw yarn for the screen gauze.

Continued on front page F term (reference) 4L041 AA07 AA20 BA02 BA05 BA21 BA46 BC17 BC20 BD02 BD14 BD20 CA06 CA16 CB05 CB25 DD01 DD15 DD21 4L045 AA05 BA02 BA18 BA49 BA50 BA52 BA60 CA25 CB13 DA42 DA60 DC02

Claims (4)

[Claims] 1. A core is made of a copolyester containing polyethylene terephthalate as a main component, and a sheath is a copolymer polyester containing ethylene terephthalate as a main component. The breaking strength is 5.74 CN / dtex or more, the breaking elongation is 15.0 to 30.0%, A core / sheath composite monofilament having a modulus at 10% elongation of 4.85 to 6.18 CN / dtex, wherein at least the sheath portion contains 0.05 to 1.0% by weight of inorganic fine particles. Polyester monofilament for screen gauze. 2. The polyester monofilament for screen gauze according to claim 1, wherein the inorganic fine particles are titanium oxide. 3. The color tone (L) of a core-sheath type composite monofilament.
3) The polyester monofilament for screen gauze according to claim 1 or 2, wherein the value is 70 to 80. 4. The polyester monofilament for screen gauze according to claim 1, wherein the copolymerized polyester in the sheath portion copolymerizes 3.0 to 10.0% by weight of a polyalkylene glycol. .