JP3462106B2 - 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, the present invention relates to a monofilament for screen gauze suitable for precision screen printing.

[0002]

2. Description of the Related Art Silk has long been widely used as a woven fabric for printing screens, but in recent years, synthetic fiber mesh,
Stainless mesh has become widely used. In particular, synthetic fiber mesh, which has excellent elastic recovery and cost performance, is preferred. Among them, polyester monofilaments have high suitability for screens such as excellent dimensional stability and are widely used.

In the field of printing such as printing of electronic circuits, the need for high-resolution and high-precision printing has been rapidly increasing in recent years, and screen gauze is moving toward the high mesh weaving of fine filaments. . In high-mesh weaving, the contact frequency and the frictional force between the running filament and the reed blade having a small pitch are increased, and the surface of the filament is scraped off easily to generate whiskers or powdery scum. The generated scum not only stains the loom,
If a part of it is woven into the screen gauze, it becomes a drawback of printing during precision printing.

Therefore, many improvement techniques have been proposed so far for the purpose of reducing the occurrence of scum. For example, Japanese Unexamined Patent Publication No. 62-276048 proposes a composite monofilament having a core of polyester and a sheath of a polymer such as nylon which is not easily shaved. Although the use of nylon can prevent scum from occurring in the monofilament, it is completely satisfactory as a screen material, such as lack of dimensional stability due to high hygroscopicity of nylon, and restriction of screen application field due to low chemical resistance of nylon. I haven't been able to do it.

Further, Japanese Patent Application Laid-Open No. 2-289120 proposes a composite monofilament having a core of polyester and a sheath of a copolyester having a glass transition temperature (Tg) of 35 to 73 ° C. Tg as a copolymer
Although the proposed composite filament, in which the softness of the polymer is improved by lowering the temperature, certainly has the effect of reducing the degree of scum generation, the scum generation factor
In reality, it is not possible to completely prevent the occurrence of scum with the proposals seen at the center.

[0006]

The present invention completely prevents the generation of scum during weaving, which is a drawback of the conventional monofilaments for screen gauze, and further provides good printing accuracy without misalignment. An object is to provide a monofilament for a screen gauze.

[0007]

The object of the present invention is a core-sheath composite type polyester monofilament for screen gauze, wherein the sheath component is represented by the following general formula (1) and / or the following general formula (2). The diol component to be used is polyethylene terephthalate copolymerized with 5 to 14 mol% with respect to the dicarboxylic acid component, and the area ratio of core: sheath is 50: 50-8.
This can be achieved by using a polyester monofilament for screen gauze characterized by being in the range of 0:20.

[0008]

[Chemical 3] General formula (1)

[0009]

[Chemical 4] General formula (2) (n and m are integer values from 3 to 10. R _{1 to} R
_{2n + 2m} is a hydrogen atom, or a methyl group or an ethyl group, and at least one is a methyl group or an ethyl group. )

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
In the present invention, a fineness monofilament of 7 to 20 d is used to obtain a high density screen of 250 to 400 mesh (lines / inch) for the purpose of high resolution and precise level printing. In the screen tensioning process, a tension of a certain value or more is required for the dimensional stability of the mesh. Tension is determined by strength (g / d) × mesh. In order to promote high meshing, generally, a finer monofilament may be used, but even if the fineness is halved, the mesh value does not double. Therefore, the smaller the d value, the higher the strength required. In the case of 7 to 20d monofilament, the required strength is 5.6g / d or more.

In order to obtain a high breaking strength, the screen filament monofilament is generally spun so that the polymer molecules are in a low orientation state, wound, and then stretched at a high ratio to be highly oriented. The highly oriented drawn yarn becomes brittle as one of its physical properties and becomes weak against bending, shearing, scraping and the like. As a result, when weaving a high mesh screen, the degree of abrasion by the reeds increases. High mesh screen weaving,
Satisfying the two points of maintaining the high breaking strength of the filament and preventing scum generation at the same time is an important subject for obtaining a good screen.

In the present invention, this problem has been overcome by using a core-sheath type composite filament composed of two kinds of fiber-forming polymers having different physical properties. Examples of the type of polyester as the core component used in the present invention include aromatic polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and polyethylene naphthalate (PEN), or polyethylene succinate and polycaprolactone. A variety of aliphatic polyesters are available. Among them, PET is particularly preferably used from the viewpoints of operability during melt spinning and manufacturing cost competitiveness.

The PET used in the present invention is 5.6 g /
In order to obtain a filament strength of d or more, IV of 0.
It is preferable to use a polymer having a high viscosity range of 60 to 0.90. Particularly preferably, PET with an IV of 0.65 to 0.85 is used.

On the other hand, the copolyester used in the present invention is one in which the third (4) component is contained in the glycol component of polyethylene terephthalate. Among these, as the copolymerizable monomer used for the acid component, a low melting point,
Aromatic dicarboxylic acids such as isophthalic acid, naphthalene dicarboxylic acid, 5-sodium sulfoisophthalic acid and bisphenol A, and / or alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid are copolymerized for the purpose of imparting other functions. I don't mind.

The copolymerizable monomer used as the diol represented by the general formula (1) includes neopentyl glycol, 2,5-dimethyl-2,5-hexanediol, and the like. As the copolymerizable monomer to be used, 3-hydroxy-2,2-dimethyl-propanoic acid, 3-hydroxy-2,2-dimethyl-propyl ester and the like are preferably used because of their polymerizability and versatility as chemical products. To be These copolymerized monomers exert the effect of effectively softening the polyester.

An appropriate range of the copolymerization ratio of the copolyester used in the present invention is determined on the basis that physical properties suitable for the composite monofilament for screen gauze are obtained.

The optimum copolymerization ratio for the present invention is such that the diol component is 5 to 5 parts of the dicarboxylic acid component of the polyester.
It is 14 mol%, and more preferably 5 to 11 mol%.
If it is less than 5 mol%, the effect of softening the polyester becomes insufficient, and the degree of abrasion due to the reeds increases. On the other hand, if it exceeds 14 mol%, the molecular structure becomes too loose and is excessively softened, and even if the breaking strength is high, the rise of the strength-elongation curve becomes very gentle,
The strength in the practical range cannot be obtained, and neither is preferable.

The composite monofilament for screen gauze of the present invention is 5.6 g which is necessary for producing a high mesh screen.
In order to secure a strength of / d or more, an IV polymer in a high viscosity range is used. The IV of the core polymer is 0.60 as described above.
It is preferably 0.90 and the sheath polymer is 0.60 to 0.80. A particularly preferred IV range for the sheath polymer is 0.65 to 0.75.

The sheath polymer retains sufficient softness and toughness as a measure against abrasion due to the reed for a high mesh screen. It is not clear in detail why this polymer structure has such effective abrasion resistance, but it is a structure with an appropriate side chain, so it has side chains such as polyethylene glycol and polymethylene glycol. It is considered that the molecular structure does not become too loose as compared with the case where it does not have a chain, and moderate softness can be obtained while maintaining toughness.

The polyester for core and sheath used in the present invention 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.

Known additives such as antioxidants, light stabilizers, antistatic agents, etc., and various particles such as titanium oxide, silicon oxide, calcium carbonate, etc. are added to the polymer used in the present invention. Good.

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 of the present invention is not particularly limited, but a circular shape is optimal. Atypical cross-section yarns may cause halation in the curing process of the photosensitive emulsion to reduce printing accuracy, or the tension of the filaments may become incomplete due to the twisting of the filaments when the fabric is stretched, resulting in a decrease in the uniformity of opening. Therefore, it cannot be used except in special cases.

The shape of the core component is not particularly limited, but it is preferable that the core component is not exposed to the surface layer.
Dimensional stability of the screen after tensioning The optimum shape and arrangement of the upper core is a single circle concentric with the sheath.

The core: sheath area ratio has an appropriate range in relation to the filament strength and the resistance to abrasion due to the reed during weaving, and the core: sheath = 50: 50 to 80:20, particularly preferably 60. It is necessary to be: 40 to 70:30. If the ratio of the sheath component exceeds the above range, the filament strength will be insufficient. On the other hand, if the ratio of the sheath component is less than the above range, frictional damage to the thin skin portion due to uneven thickness occurs.

[0025]

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. Breaking strength / elongation: In accordance with JIS-L-1013, using an AGS-1KNG autograph tensile tester manufactured by Shimadzu Corporation, the sample was stretched and broken under the conditions of a sample yarn length of 20 cm and a constant speed pulling speed of 20 cm / min. The strength and elongation at that time were determined.

B. Evaluation of scum: A screen woven fabric was woven at a rotation speed of 300 rpm using a Sruzer type loom, and the weaving length up to the point at which the weaving could not be maintained because the reeds were contaminated and the normal weaving could not be maintained. As for the evaluation, those having a weaving length of 500 m or more were evaluated as good ◯, and those having a weaving length of less than 500 m were evaluated as poor x.

C. Screen dimensional stability Distortion of the print pattern due to dimensional instability when printing 1000 sheets was observed, and no distortion was evaluated as ◯ and distortion was evaluated as x.

Example 1 A polyethylene terephthalate polymer having an intrinsic viscosity (IV) of 0.685 was used as a core component and 10 mol% of neopentyl glycol (NPG) was copolymerized with the dicarboxylic acid component to obtain an IV of 0.1. Orifice diameter φ0.35 mm according to a conventionally known composite spinning method using 74 ± 0.01 copolymerized polyethylene terephthalate polymer as a sheath component.
The core: sheath composite ratio (area ratio) is 67:
33 composite monofilaments were spun at a spinning temperature of 295 ° C. and a winding speed of 1500 m / min. The obtained unstretched monofilament was stretched through a 78 ° C. roller heater and a 150 ° C. plate heater at a speed of 800 m / min to give a breaking strength of 7.0 g / d and a breaking elongation of 20% of 12.0 d.
A composite monofilament was obtained. The monofilament was woven into a 300-mesh high-mesh gauze. Table 1 shows the polymer composition, physical properties, monofilament characteristics, and weaving evaluation results.

Example 2 A polyethylene terephthalate polymer having an intrinsic viscosity of 0.685 according to Example 1 was used as a core component, and 2,5-dimethyl-2,5-hexanediol (DMH) was used in a proportion of 7 mol% instead of neopentyl glycol. A composite monofilament was obtained by using a copolymerized polyethylene terephthalate polymer having a polymerized IV of 0.70 as a sheath component. The breaking strength of the monofilament is 6.8 g / d and the breaking elongation is 20.
%Met. The monofilament was woven into a 300-mesh high-mesh gauze. Polymer composition, physical properties,
Table 1 shows the characteristics of the monofilaments and the evaluation results of weaving.

Example 3 A polyethylene terephthalate polymer having an intrinsic viscosity of 0.685 according to Example 1 was used as a core component, and 3-hydroxy-2,2-dimethyl-propanoic acid, 3-hydroxy-2 was used instead of neopentyl glycol. , 2
A composite monofilament was obtained using as a sheath component a copolymerized polyethylene terephthalate polymer having IV of 0.70 in which 5 mol% of dimethyl-propyl ester (HPN) was copolymerized. The breaking strength of the monofilament is 6.5 g /
d, the elongation at break was 20%. The monofilament was woven into a 300-mesh high-mesh gauze. Table 1 shows the polymer composition, physical properties, monofilament characteristics, and weaving evaluation results.

Comparative Examples 1 and 2 After obtaining a composite monofilament according to Example 1, a high mesh gauze was prepared. However, copolymerized polyethylene terephthalate in which the copolymerization of neopentyl glycol was changed to 3 mol% and 20 mol% was used as a sheath component. Table 1 shows the polymer composition, physical properties, monofilament characteristics, and weaving evaluation results.

[0033]

[Table 1]

In Comparative Example 1 (Experiment No. 1), the polymer was too hard, and in Comparative Example 2 (Experiment No. 5), the polymer was too soft, so scum was generated during weaving, and stable weaving was difficult. However, Examples 1 to 3 according to the present invention
In (Experiment Nos. 2 to 4), a stable weaving state and a high-mesh screen gauze with good quality were obtained.

Examples 4 to 6 and Comparative Examples 3 and 4 After obtaining a composite monofilament according to Example 1, a high mesh gauze was prepared. However, monofilaments having different core: sheath composite monofilaments were used.
Table 2 shows the characteristics of the monofilament and the results of weaving evaluation.
Shown in.

[0036]

[Table 2]

In Comparative Example 3 (Experiment No. 6), the screen tension was poor due to the insufficient breaking strength, resulting in poor screen dimensional stability. In Comparative Example 4 (Experiment No. 10), the weaving sheath layer was Although the core was partially broken and exposed, and scum was slightly generated, weavability was poor, but Examples 4 to 6 of the present invention were performed.
(Experiment No. 7 to 9) has no scum during weaving,
A high mesh screen having good dimensional stability of the screen was obtained.

[0038]

Industrial Applicability The core-sheath type composite monofilament made of the polyester of the present invention comprises, as a sheath component, a copolymerized polyester polymer having a specific composition which has excellent physical properties such as softness and does not cause scum during weaving. By using polyester as a component, which gives excellent mechanical properties such as high tensile strength of monofilament, the problem of scum generation during high mesh screen weaving, which has been a problem in the past, is solved and good printing accuracy is obtained. It is also possible to supply gauze.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-11-241227 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) D01F 8/14 B41N 1/24

Claims (2)

(57) [Claims] 1. A core-sheath composite type polyester monofilament for screen gauze, wherein the diol component represented by the following general formula (1) and / or the following general formula (2) is contained in the dicarboxylic acid component. Polyester terephthalate copolymerized with 5 to 14 mol% and having a core: sheath area ratio in the range of 50:50 to 80:20. [Chemical 1] General formula (1) General formula (2) (n and m are integer values from 3 to 10. R _{1 to} R
_{2n + 2m} is a hydrogen atom, or a methyl group or an ethyl group, and at least one is a methyl group or an ethyl group. ) 2. The core component has an intrinsic viscosity (IV) of 0.60.
The polyester monofilament for screen gauze according to claim 1, which is 0.90 polyethylene terephthalate and has a sheath component of IV 0.60 to 0.80.