JPH04194021A - Naphthalate polyester fiber and its production - Google Patents

Abstract

PURPOSE:To obtain the subject fiber, excellent in strength, elastic modulus, etc., with high toughness and suitable as tire cords, belt materials, etc., by polymerizing ethylene naphthalate as a principal component to a specific intrinsic viscosity. CONSTITUTION:The objective fiber is obtained by polycondensing (A) naphthalene-2,6-dicarboxylic acid with (B) ethylene glycol. The aforementioned fiber contains >=90mol% ethylene 2,6-naphthalate and has >=0.65 intrinsic viscosity, >=9.0g/de strength, >=210g/de elastic modulus and >=26.0 silk factor.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a naphthalate polyester fiber with high strength, high modulus of elasticity, and high toughness, and a method for producing the same, particularly for use in industrial materials such as tire cords and belt materials. The present invention relates to fibers suitable for reinforcing fibers and methods for producing the same.

[Conventional technology]

Conventionally, high-strength naphthalate polyester fibers have a high strength of up to 10.3 g/de when stretched and heat treated under specific stretching conditions, as described in Japanese Patent Publication No. 55-1371. It is known that it can be converted into In these cases, the elongation of the yarn is extremely low at 5.1 to 5.5%, and the silk factor defined as strength (g/de) x 'elongation 1 [at X] is 20 to 5.5%. 23.5
It's nothing more than that. When such low elongation yarns are twisted and used for tire cords and belt materials, the so-called strength utilization rate is low, so only low strength cords can be obtained, and the performance of naphthalate polyester fibers cannot be fully demonstrated. I can't.

In addition, Japanese Patent Application Laid-open No. 50-16739 discloses a spinning speed of 7.5.
Fibers with different crystal forms were obtained by high-speed spinning at 00 m/min, but the elongation was 9.5% and the silk factor was 25.0, which was relatively good, but the strength was The strength remains at a low strength level of 8.1 g/de.

[Problem to be solved by the invention]

An object of the present invention is to provide a high-strength and high-toughness naphthalate polyester fiber and a method for producing the same, and in particular to provide a raw fiber suitable for reinforcing tire cords and belt materials and a method for producing the same. .

[Means to solve the problem]

The present invention contains 90 ethylene-2,6-naphthalate units.
Naphthalate polyester fiber containing mol% or more and having an intrinsic viscosity of 0.65 or more, having a strength of 9.0 g/de or more, an elastic modulus of ztOg/de or more, and a silk factor of 26.0 or more. It is polyester fiber.

The naphthalate polyester constituting the naphthalate polyester fiber of the present invention has 90 polymer repeating units.
A polyester in which mol% or more is ethylene-2,6-naphthalate units.

Such polyesters include polyethylene-2,
6-naphthalate is typical, but a copolymer containing a suitable third component in a proportion of 10 mol% or less may also be used.

Generally, polyethylene 2,6-naphthalate is synthesized by polymerizing naphthalene-2,6-dicarboxylic acid or a functional derivative thereof in the presence of a catalyst under appropriate reaction conditions. In this case, if one or more appropriate third components are added before the polymerization of polyethylene-2.6-naphthalate is completed, a copolymerized polyester can be synthesized. Suitable third components include (a) compounds having two ester-forming functional groups: aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid; cyclopropanedicarboxylic acid, cyclobutane; Alicyclic dicarboxylic acids such as dicarboxylic acid and hexahydroterephthalic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, naphthalene-2,7-dicarboxylic acid, diphenyldicarboxylic acid; diphenyl ether dicarboxylic acid, diphenylsulfonic dicarboxylic acid, Carboxylic acids such as diphenoxyethanedicarboxylic acid and sodium 3,5-dicarboxybenzenesulfonate; Oxycarboxylic acids such as glycolic acid, p-oxybenzoic acid, and P-oxyethoxybenzoic acid; propylene glycol, trimethylene glycol, diethylene glycol , tetramethylene glycol, hexamethylene glycol, neobenzene gelylcol, p-xylylene glycol, 1.4
-Cyclohexane dimetatool, bisphenol A, P
, P'-diphenoxysulfone-1,4-bis(β-
hydroxyethoxy)benzene, 2,2-bis(p-β
- Oxy compounds such as hydroxyethoxyphenyl)propane, polyalkylene glycol, P-phenylenebis(dimethylcyclohexane), or functional derivatives thereof; derived from the above carboxylic acids, oxycarboxylic acids, oxy compounds, or functional derivatives thereof. Highly polymerized compounds, and (b) compounds having one ester-forming functional group, such as benzoic acid, benzoylbenzoic acid, benzyloxybenzoic acid, and methoxypolyalkylene glycol, are included. Furthermore, (C) a compound having three or more ester-forming functional groups, such as glycerin, pentaerythritol, trimethylolpropane, etc., can also be used as long as the polymer is substantially linear.

Further, it goes without saying that the polyester may contain a matting agent such as titanium dioxide and a stabilizer such as phosphoric acid, phosphorous acid, and their esters.

The naphthalate polyester fiber of the present invention has an intrinsic viscosity of 0.65 or more, preferably 0.7 to 1.0.
It is. In the present invention, the intrinsic viscosity means that the polymer is mixed with a mixed solvent of phenol and orthodichlorobenzene (volume ratio 6:
This is the value determined from the viscosity measured at 35°C after dissolving in 4). If the intrinsic viscosity is less than 0.65, high-strength, high-toughness thread-like fibers cannot be obtained. Note that fibers with an intrinsic viscosity exceeding 1.0 tend to have poor spinning process properties and are not desirable in practical terms.

The naphthalene polyester fiber of the present invention has high strength and high toughness, and is particularly suitable for reinforcing tire cords and belt materials, and its strength is 9.0 g/de or more, preferably 9.5 g/de or more. , elastic modulus is 210g/de
Above, preferably 230 to 260 g/de, and silk factor [strength (g/de) x, r
Elongation 1 [tewashi]] is 26.0 or more, preferably 26.5 or more
It is 32.0.

If the strength is less than 9.0 g/de, the strength will be low and the durability will be poor when used as an industrial material such as a tire cord.

In addition, if the elastic modulus is less than 210 g/de, the performance will be poor when used as a belt material for radial tires, for example, and the naphthalate polyester fiber will not be able to fully demonstrate its high elastic modulus properties. .

Furthermore, if the silk factor is less than 26.0, the strength will be greatly reduced during the twisting process and the cord will be formed into a cord, resulting in a tire cord with poor durability.

Such naphthalate polyester fibers include naphthalate polyester containing 90 mol% or more of ethylene-2,6-naphthalate units and having an intrinsic viscosity of 0.6 or more.
Spinning speed 120-1.200 m/min, spinning draft 20
The undrawn yarn is melt-spun at a temperature of ~250°C, and the birefringence of the undrawn yarn is set to 0.050 or less, and the undrawn yarn is wound up and supplied to a hot drawing process. The first stage stretching is performed between the first stage stretching rollers at a temperature of 8Q% or more of the total stretching ratio, and then the heating plate installed immediately after the first stage stretching roller is
After the second stage stretching was performed at 240°C between the first stage stretching roller and the second stage stretching roller at 220 to 245°C, the second stage stretching was performed between the second stage stretching roller and the unheated winding roller. It can be obtained by performing a limited contraction of %.

The naphthalate polyester used in the production method of the present invention has an intrinsic viscosity of 0.70 or more. If the intrinsic viscosity is less than 0.70, fibers with high strength, high toughness, and good quality cannot be obtained.

When the naphthalate polyester fibers of the present invention are melt-spun, after being discharged from a spinneret, the fibers are passed through a heating zone at a temperature above the melting point for delayed cooling, and then cooled and solidified with cooling air. Next, after applying an oil agent, the spinning speed was increased to 120 to 1,200.
m/min, spinning draft 20-250, and birefringence (
Δn) is 0.050 or less.

When the spinning speed exceeds 1,200 m/min, Δn of the resulting undrawn yarn becomes large and the drawability decreases.

On the other hand, if the spinning speed is less than 120 m/min, the stability of the spun yarn will decrease, leading to occurrence of yarn breakage.

The spinning draft is defined as the ratio of the spinning winding speed and the spinning discharge linear speed, and specifically, it was determined from the following formula (1).

(In the formula, D is the hole diameter of the spinneret, ■ is the spinning winding speed, and W is the volume discharge per single hole.) When the spinning draft exceeds 250, Δn increases and the spinning condition decreases. On the other hand, if the spinning draft is less than 20, the spun yarn will sway significantly and the spinning stability will be lacking.

When Δn exceeds 0.050, stretchability decreases, resulting in high strength and
High toughness fiber cannot be obtained.

The method for hot stretching the undrawn yarn thus obtained will be explained below.

That is, the stretching of the present invention consists of at least two stretching steps and a limited heat shrinkage step in the final stage.

First, in the first stage stretching, stretching is performed in a heating supply row at 150 to 170° C. until immediately before entering the heat shrinking step, that is, at a stretching ratio of 80% or more up to the final stretching step. If the stretching temperature is less than 150° C., preheating will be insufficient, resulting in excessive stretching, and the total stretching ratio will remain at a low value. On the other hand, if the roller temperature exceeds 170°C, crystallization occurs during stretching, and the total stretching ratio remains at a low value.

Furthermore, if the stretching ratio in the first stage stretching is less than 80% of the stretching ratio up to the final stretching step, the achieved strength and the achieved elastic modulus will be low.
Moreover, only fibers with low toughness expressed by silk factor can be obtained, and fibers with the thread quality specified in the present invention cannot be obtained.

Next, the second stage stretching is performed using a combination of a first stage stretching roller of 170 to 220"C and a heating plate of 210 to 240"C.The temperature of the heating plate is preferably set higher than the temperature of the first stage stretching roller. preferable.

If the temperature of the first-stage stretching roller is less than 170°C, the second-stage stretching temperature is too low and high-magnification stretching is not possible;
If it exceeds this, the structure is fixed by crystallization in the first stage stretching, which does not yet have sufficient orientation, resulting in the total stretching ratio remaining at a low value.

If the temperature of the heating plate is less than 210° C., the second stage stretching temperature is too low, similar to the roller temperature, and high-magnification stretching cannot be performed.

On the other hand, if the drawing temperature exceeds 240° C., the drawing temperature is too high and the fibers may fuse and break, and even if breakage occurs, the fibers will be damaged and the quality of the yarn will deteriorate.

Although the temperature of the heating plate may be constant, it is particularly preferable to use a heating plate with a temperature gradient such that the temperature increases from the inlet side to the outlet side.

In addition, instead of a heating plate, the yarn temperature is actually 210 ~
It is also possible to use a heating oven set at 210 to 245°C so that the temperature reaches 240″C.

In this second stage stretching, the remainder of the first stage stretching is usually carried out. Although it is preferable to carry out the second-stage stretching in multiple stages if appropriate conditions are met, there are restrictions from an industrial perspective in terms of equipment costs, so in reality, the stretching is carried out in two stages. conduct.

When performing multi-stage stretching of three or more stages, the stretching conditions are as follows:
The key is to increase the temperature towards the later stage.

From the viewpoint of stretchability, it is preferable to install a heating plate and a heating plate following the heating roller. According to the results of the inventors' basic study,
It is important that the drawing tension of the naphthalate polyester fibers be set to a relatively low value.

Normally, polyethylene terephthalate fibers can withstand a drawing tension of 2.5 to 3.0 g/de in the latter stage of multi-stage drawing, but naphthalate polyester fibers can withstand a drawing tension of 2.5 to 3.0 g/de. 0～
About 2.5 g/de is preferable. From this perspective,
Providing a heating plate having a higher temperature than the heating roller of the first stage stretching roller, that is, the heating roller of the second stage stretching, and lowering the stretching tension contributes to improving the stretching property.

Subsequently, the final stage of limited heat shrinkage is performed between the second stage stretching roller and the unheated take-up roller.

In order to promote crystallization of the fibers subjected to the second stage drawing,
The temperature of the second stage stretching roller is preferably higher than the heating plate temperature, and the temperature is 220 to 245°C. If the temperature of the second stage drawing roller is less than 220°C, the heat setting effect will not be sufficient and the silk factor will decrease, while if it exceeds 245°C, the yarn will tend to deteriorate due to heat.
The strength will decrease.

The degree of limited contraction at this time needs to be 2 to 5%. In the case of naphthalate polyester fiber, the inventors have found that under limited shrinkage of 2 to 5%, the strength hardly decreases, the elastic modulus decreases little, and the elongation increases, so the silk factor The improvement effect is significant. If the restricted shrinkage is less than 2%, the effect of improving the silk factor will be small, while if the restricted shrinkage exceeds 5%, the strength will decrease and
This is not preferable because the elastic modulus decreases significantly.

[Example〕 EXAMPLES The present invention will be explained in further detail by way of Examples below.

Note that the strength and elongation were measured according to JIS L-1070. In addition, the elastic modulus is measured using a viscoelasticity measuring device manufactured by Wakagi Seisakusho.
The dynamic elastic modulus (E') measured at room temperature and 10 Hz using a spectrometer was used.

Examples 1 to 6, Comparative Examples 1 to 8 Polyethylene-2,6-naphthalate having an intrinsic viscosity of 0.83 was melt-spun at a polymer temperature of 312°C from a spinneret having 48 holes and a circular spinning hole with a hole diameter of 0.40 mm. When doing so, the length 30cm, 33 provided at the bottom of the spinneret
After passing through a heating tube at 0° C., it was cooled and solidified over a length of 300 mm with cooling air at a relative humidity of 65% and a temperature of 25° C.

The cooled and solidified yarn was coated with an oil agent using an oiling roller, and then wound at 500 m/min.

At this time, the draft is 52, and the fineness of the undrawn yarn is 126.
0de, and the birefringence was 0.011.

After applying 1% britension to this undrawn yarn, first-stage drawing (magnification ratio DRI) is performed between a heated supply roller (FR) and a first-stage drawing roller (IR), and then the first-stage drawing roller (heating) and the heating plate (H
Second-stage stretching (magnification ratio DR2) was carried out between the first-stage stretching roller and the second-stage stretching roller (2R) using a combination of the following: P, 70CI).

Further, as a limited heat shrinkage step, a shrinkage process (shrinkage ratio DR3) was performed between a second stage stretching roller (heated) and a non-heated winding roller (WR), and the film was wound at 150 m/min. At this time, the surface temperatures of the rollers and heating plates, the draw ratio of each stage, the total draw ratio (TDR), the drawing condition, and the yarn physical properties of the obtained drawn yarn are shown in Table 1.

(Left below) Examples 7 to 9, Comparative Examples 9 to 12 Polyethylene-2,6-naphthalate having an intrinsic viscosity of 0.83 is melt-spun at a polymer temperature of 312°C from a spinneret having a circular spinning hole of 48 holes. After passing through a 30 cm long heated cylinder at 330°C installed at the bottom of the spinneret, the relative humidity was 65°C over a length of 300 mm.
%, and was cooled and solidified with cooling air at a temperature of 25°C.

The cooled and solidified yarn was coated with an oil agent using an oiling roller, then wound around a bobbin and subjected to drawing. At this time,
Table 2 shows the results of spinning by varying the discharge amount, spinneret diameter, and spinning (winding) speed.

The conditions of Example 1 were used for the stretching temperature conditions.

Note that Table 2 also shows Example 1.

(The following is a blank space) [Effects of the Invention] The present invention can provide a naphthalate polyester fiber with high strength and high toughness, which is particularly suitable for reinforcing tire cords and belt materials.

Patent applicant Teijin Co., Ltd. Agent: Patent Attorney Takashi Shirai

Claims (4)

[Claims] (1) A naphthalate polyester fiber containing 90 mol% or more of ethylene-2,6-naphthalate units and having an intrinsic viscosity of 0.65 or more, and a strength of 9.0 g/de or more,
A naphthalate polyester fiber having an elastic modulus of 210 g/de or more and a silk factor of 26.0 or more. (2) Strength is 9.5g/de or more, elastic modulus is 230g/de
The naphthalate polyester fiber according to claim 1, which has a silk factor of 26.0 or more and a silk factor of 26.0 or more. (3) A naphthalate polyester containing 90 mol% or more of ethylene-2,6-naphthalate units and having an intrinsic viscosity of 0.70 or more is spun at a spinning speed of 120 to 1,200 m/min.
Melt spinning is carried out at a spinning draft of 20 to 250, and the undrawn yarn is wound up with a birefringence index of 0.050 or less, and the wound undrawn yarn is supplied to a hot drawing process, with a birefringence of 150 to 170.
℃ heating supply roller and 170 to 200 ℃ first stage stretching roller at a magnification of 80% or more of the total stretching ratio, followed by a heating plate installed immediately after the first stage stretching roller at 210° C. ~240℃, first stage stretching roller and two
It is characterized by performing second-stage stretching between second-stage stretching rollers at 20 to 245°C, and then performing limited shrinkage of 2 to 5% between the second-stage stretching roller and a non-heated take-up roller. A method for producing naphthalate polyester fiber. (4) The method for producing naphthalate polyester fibers according to claim 3, wherein the temperature of the heating plate increases from the input side to the output side.