JP2813378B2 - High shrinkage polyester fiber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a highly shrinkable polyester fiber having excellent shrinkage characteristics and a method for producing the same.

<Conventional technology> As a conventional method for obtaining a shrinkable polyester fiber,
It is well known that a copolyester obtained by copolymerizing polyethylene terephthalate with a third component is used to produce a shrinkable fiber under specific conditions.

Conventionally, various high-shrinkable fibers have been studied, but when roughly classified, those that mostly shrink during boiling water treatment or moist heat of 80 ° C or more, dry heat treatment or dyeing,
In such a treatment, there is a case in which the shrinkage hardly or only slightly shrinks, and then starts shrinking only by a heat treatment such as drying. The fiber of the present invention belongs to the former.

Examples of the type of the third component that gives high shrinkage include inphthalic acid, sodium sulfoisophthalic acid, and 2.2-bis-.
Various types such as (4'-β-hydroxyethoxyphenyl) propane are known, and as in the present invention, 2.2-
A high-shrinkage copolyester fiber using bis- (4'-β-hydroxyphenyl) propane as the third component and a method for producing the same are disclosed in JP-B-58-28374.

<Problems to be Solved by the Invention> However, the high shrinkage copolyester fiber disclosed in the above-mentioned Japanese Patent Publication No.
It is a type that shrinks at most about 10% by the above-mentioned wet heat, dry heat treatment, etc., and shrinks by the subsequent heat treatment. For example, shrink packs, especially for casings of ham etc. The shrinkage rate and shrinkage stress were insufficient for use as a non-woven fabric or string.

The purpose of the present invention is to treat the water with boiling water or wet heat of 80 ° C or more.
An object of the present invention is to provide a highly shrinkable polyester fiber which easily shrinks by dry heat treatment and exhibits a large shrinkage ratio and shrinkage stress, and also provides a packaging material such as shrink pack using the fiber. It is.

<Means for Solving the Problems> The present inventors have conducted intensive studies to achieve the above object, and as a result, as a fiber material, 2.2-bis- (4′-β-hydroxyethoxyphenyl) propane (BPE It has been found that the use of polyethylene terephthalate obtained by copolymerizing a) in a specific amount gives a copolyester fiber having sufficient shrinkage and shrinkage stress required as a final product, and has led to the present invention.

That is, the present invention relates to the following structural unit represented by [I]:
A polyester fiber mainly containing polyalkylene terephthalate having an intrinsic viscosity [η] of 0.4 or more and 0.7 or less containing not less than 25% by mole and not more than 25% by mole.
sr), dry heat shrinkage (Dsr) at 170 ° C, and
A polyester fiber characterized in that the shrinkage stress (Sr _M ) at 100 ° C. when set to 1 g / d satisfies the following conditions (1) to (3).

Wsr (%) ≧ 2.5n + 3 (1) Dsr (%) ≧ 3n (2) Sr _M (g / d) ≧ 0.20 (3) (where n represents the mol% of the above [I]. 10 ≦ n ≦ 25) The polyester constituting the highly shrinkable polyester fiber of the present invention has a part of the diol component of 2.2-bis- (4 ′).
-Β-hydroxyethoxyphenyl) propane (hereinafter, referred to as
Sometimes referred to simply as BPE. This is a polyester mainly composed of polyalkylene terephthalate containing the above structural unit [I] in an amount of 10 mol% or more and 25 mol% or less. The main polymer serving as the skeleton is, for example, a polyalkylene terephthalate such as polyethylene terephthalate or polybutylene terephthalate, with polyethylene terephthalate being preferred.

Further, in the present invention, BP as long as the effect is not impaired
It may be modified with a copolymer component other than E. However, it is preferable that the total of the structural units of these copolymer components and the structural unit of [I] is not more than 40 mol% in the polymer, especially 25% or less.

Other copolymerization components, for example, adipic acid, sebacic acid, sulfoisophthalic acid, isophthalic acid, dibasic acids such as naphthalene dicarboxylic acid, neopentyl glycol, diethylene glycol, dipropylene glycol,
Examples include polyfunctional diols such as 1,4-cyclohexanedimethanol and bisphenol A, and polyalkylene glycols such as methoxypolyethylene glycol and polyethylene glycol.

In the present invention, if the content of the structural unit [I] is less than 10 mol%, large shrinkage performance cannot be obtained, while if it exceeds 25 mol%, the fiber strength becomes insufficient. Therefore, the content of [I] is preferably 10 to 23 mol%, and particularly preferably 12 to 20 mol%.

Further, the fiber of the present invention has an intrinsic viscosity (η) of 0.40 or more and 0.70 or less when measured at a temperature of 30 ° C. in a mixed solution of phenol and tetrachloroethane in an equal amount, preferably, 0.1.
It is desirable to be in the range of 50 or more and 0.65 or less. When [η] is small, it is difficult to impart a preferable shrinkage stress to the fiber, while when it is too large, the spinnability tends to be poor.

It is not sufficient for the highly shrinkable polyester fiber of the present invention to consist only of the above-mentioned polymer composition. As shown in the following (1) to (3), the hot water shrinkage at 100 ° C. (Ws
r), dry heat shrinkage (Dsr) at 170 ° C and initial tension 0.1
The shrinkage stress at 100 ° C. (Sr _M ) when set to g / d must satisfy certain conditions.

Wsr (%) ≧ 2.5n + 3 (1) Dsr (%) ≧ 3n (2) Sr _M (g / d) ≧ 0.20 (3) (where n represents mol% of the structural unit [I]; 10 ≦ n ≤
25) If non-woven fabric for ham casing is manufactured using fibers that satisfy Wsr <2.5n + 3 or Dsr <3n, for example, shrinkage during heat treatment does not sufficiently occur, so it is completely unsuitable for casing. It will become something.

In terms of specific values, Wsr is preferably 25% or more,
Especially 30% or more is preferable. The upper limit is not particularly limited,
It should be noted that if the copolymerization amount is increased in order to increase Wsr, the fiber strength becomes insufficient as described above. Preferably, Wsr does not exceed 75%.

Dsr is preferably at least 25%, and more preferably at least 30%. The upper limit of Dsr is the same as Wsr.
It is preferable to keep it to 75%.

Here, the hot water shrinkage at 100 ° C (Wsr) is determined by adding a fiber of the original yarn length (L ₀ ) into hot water at 100 ° C without applying a load, L) is a value determined as a percentage of the original yarn length (L ₀ ). In addition, when measuring the shrinkage length and the yarn length, the measurement was performed with a load of 50 mg / d.

The dry heat shrinkage at 170 ° C. (Dsr) is determined by measuring the fiber length (L ′ ₀ ) supplied to an air atmosphere heated to 170 ° C. without applying a load, and the shrinkage length after 15 minutes (Ls ₀ ). L ′) is measured and the value is calculated as a percentage of the original yarn length (L ′ ₀ ). In addition, when measuring the shrinkage length and the yarn length, 50 mg / d
The load was measured.

Next, if the shrinkage stress (Sr _M ) at 100 ° C. when the initial tension is set at 0.1 g / d is smaller than 0.20 g / d, for example, when casing a ham, the strength of the nonwoven fabric is weak, so that the material is torn or It is not preferable in that it wraps the ham neatly and loses the so-called fitness.

The heat shrinkage stress (Sr _M ) of the fiber bundled to 100 to 200 denier was 0.1 g / d for the initial tension and 300 ° C./18 for the temperature rise rate.
It is a value measured stress at 100 ℃ in 0 seconds, for example,
It can be measured using KE-2 type machine manufactured by Kanebo Engineering Co., Ltd.

Polyester fiber having such various properties is obtained by, for example, spinning a polyalkylene terephthalate obtained by copolymerizing BPE in an amount of 10 to 25 mol% in a usual melt spinning apparatus, and then drawing the undrawn yarn at 65 to 80 ° C. The undrawn yarn is drawn at 70 to 95% of the cutting magnification (= elongation at break) of the undrawn yarn in a warm water bath, and after the drawing, the fiber is usually subjected to a treatment at 75 ° C. or less. it can. Here, the stretching bath temperature is 70-80
° C is more preferable, and the draw ratio is the cut ratio of the undrawn yarn.
More preferably, it is 75 to 85%. Stretching bath temperature is low and the Sr _M be high shrinkage obtained a target becomes less fence than 0.20 g / d is not preferred. If the bath temperature is too high, the target shrinkage cannot be obtained.

On the other hand, if the draw ratio is out of the above range and too low, the target shrinkage ratio will not be attained, and the yarn will have low shrinkage. On the other hand, if the amount is too high, thread breakage or the like occurs in the bath, and roller winding occurs, which is not preferable.

In particular, in order to obtain the polyester fiber of the present invention, it is preferable to take the conditions of 75 ° C. or less, particularly 70 ° C. or less in each treatment after drawing, that is, crimping, application of heat such as drying. If it is out of the range, it is difficult to obtain a fiber having good shrinkage characteristics.

The fiber of the present invention obtained by such a production method can be formed into a yarn by a known method as a long fiber or a short fiber, or a woven or knitted fabric, or a nonwoven fabric. It is extremely effective as a packaging material for shrink packs and the like, and is particularly suitable for non-woven fabrics and strings for ham and sausage casings that require excellent shrinkage characteristics.

<Examples> Next, the present invention will be described specifically with reference to examples, but the present invention is not limited thereto.

Example 1 Modified polyethylene terephthalate having a content of 12 mol% of the above structural unit [I] derived from 2,2-bis- (4'-β-hydroxyethoxyphenyl) propane was polymerized by a conventional method to give a chip. did. This chip was dried under reduced pressure at 150, discharged from a circular nozzle having a diameter of 0.25 mm and 500 holes, wound up at 700 m / min, and converged to form a 700,000 denier tow. After drawing in a hot bath at a temperature of 2 ° C. (2 baths) and a draw ratio of 3.85 (80% of the cutting ratio of the undrawn yarn), it was mechanically crimped and dried in a hot air dryer at 70 ° C. for 10 minutes.

 The performance of the obtained fiber was as follows.

Comparative Example 1 The same unstretched tow as in Example 1 was stretched in a hot bath at a stretching temperature of 60 ° C. at a stretching ratio of 3.35 (70% of the cutting ratio), then mechanically crimped, and dried with hot air at 70 ° C. for 10 minutes. The performance of the obtained fiber was as follows.

As is clear from Table 2, when the stretching temperature and the stretching ratio are low, Wsr and Dsr are high, but the shrinkage stress (Sr _M ) is small and 0.20 g / d.
It is as follows.

Comparative Example 2 A polyester fiber was obtained in the same manner as in Example 1 except that the drying conditions after the application of the mechanical crimp were changed to 80 ° C. × 10 minutes.

As a result, Wsr and Dsr showed moderate values, but Sr _M was 0.1
It was 4 g / d and the stress was low.

Example 2 Using polyethylene terephthalate obtained by copolymerizing 2,2-bis- (4 '-. Beta.-hydroxyethoxyphenyl) propane (BPE) at various ratios, [.eta.] Make staple toe, 1 bath 70 ° C, 2 bath 80
In a hot bath at 80 ° C, stretched in two steps at 3.8 times (70% of cutting magnification), mechanically crimped 12 pieces per inch, and dried in a hot air dryer at 65 ° C.
Dried for 15 minutes. Table 3 shows the obtained results.

Comparative Example 3 The same spinning and drawing as in Example 2 using polyethylene terephthalate ([η] 0.56) obtained by copolymerizing 5 mol% of 2,2-bis- (4′-β-hydroxyethoxyphenyl) propane. Fibers were formed by employing drying conditions. Table 4 shows the obtained results.

As can be seen from Table 4, if the BPE copolymerization amount is low, a fiber having a quality of Wsr of 30% or more cannot be obtained.

<Effects of the Invention> The polyester fiber of the present invention exhibits a higher shrinkage rate and a higher shrinkage stress than conventional high-shrinkage polyester fibers, and is therefore a fiber extremely useful for casings of shrink packs, especially hams. Material.

Claims (1)

(57) [Claims] (1) a structural unit represented by the following [I]:
A polyester fiber mainly containing polyalkylene terephthalate having an intrinsic viscosity [η] of 0.4 or more and 0.7 or less containing not less than 25 mol% or less, and a hot water shrinkage rate (Wsr) at 100 ° C. of 17
Dry heat shrinkage at 0 ° C (Dsr) and shrinkage stress at 100 ° C when initial tension is set to 0.1g / d (SrM) satisfy the following conditions (1) to (3) And polyester fiber. Wsr (%) ≧ 2.5n + 3 (1) Dsr (%) ≧ 3n (2) SrM (g / d) ≧ 0.20 (3) (where n indicates mol% of the above [I]. 10 ≦ n ≦ 25 )