JPS63152411A - Production of flame-retardant polyester fiber - Google Patents

Abstract

PURPOSE:To obtain the titled fiber having flame-retardancy and low shrinkage, by producing a drawn polyester yarn copolymerized with a specific amount of a bifunctional phosphorus compound, heat-treating the yarn under fixed length at a specific temperature and heat-treating in relaxed state. CONSTITUTION:A drawn polyester yarn copolymerized with a bifunctional phosphorus compound [e.g. dimethyl phenylphosphonate, (2-carboxyethyl) methylphosphinic acid, etc.] in an amount of 0.7-3.0wt%, preferably 0.9-2.0wt% in terms of phosphorus element is heat-treated at an elongation ratio of 0.98-1.02 at a temperature T1 satisfying the formula Tc-20<=T1<=Tc+20 [Tc is crystallization temperature of unoriented polyester ( deg.C)] and then subjected to mechanical crimping. The objective fiber is produced by heat-treating the product in relaxed state at a temperature T2 satisfying the formula Tc-70<=T2<=Tc-20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing polyester fibers having excellent combustibility. More specifically, the present invention relates to a method for producing polyester fibers that are flame retardant and have a low shrinkage rate.

[Prior Art] Polyester fibers have excellent physical properties and are therefore widely used for clothing, bedding, interior decoration, and the like. However, polyester fibers have been unable to be used in applications subject to flame retardant regulations due to insufficient flame retardancy.

Conventionally, techniques for making polyester fiber flame retardant include a method of blending a flame retardant imparting substance during polymer production and copolymerizing or blending (Japanese Patent Publication No. 55-41610 @ Publication, Japanese Patent Publication No. 52-8889); Method of imparting flame retardancy through post-processing after formation (Special Publication No. 53-4
4599), and a method in which antimony oxide is blended during spinning to form a fibrous material and then treated with a post-processing flame retardant (JP-A-50-43221, JP-A-5
0-94226) is known.

None of these methods achieves a sufficient level of flame retardancy, and especially when polyester fibers and cellulose fibers are used together, such as in blends, interweaving, etc., it is difficult to achieve a sufficient level of flame retardancy. A large amount of flame retardant must be applied during the processing process, which deteriorates the fabric's properties such as texture and weather resistance, making it unusable for anything other than special purposes.

[Problems to be Solved by the Invention] The purpose of the present invention is to eliminate the drawbacks of the prior art, typified by the rough texture caused by the high shrinkage rate of fibers, and to produce polyester fibers with excellent flame retardancy. It's about doing.

[Means for Solving the Problems] The object of the present invention is to prepare a drawn polyester yarn copolymerized with a difunctional phosphorus compound in an amount of 0.7 to 3.0% by weight based on the amount of phosphorus element expressed by the following formula (1). At a satisfactory temperature T1, the elongation rate is 0.
To achieve this by a method for producing flame-retardant polyester fiber, which is characterized in that after heat treatment at 98 to 1.02, mechanical crimping is performed, and then relaxation heat treatment is performed at a temperature T2 that satisfies the following formula (2). I can do it.

Ding c-20≦T1('C)≦TC+20・・・・・・(
1) The present invention will be explained in detail below.

The undrawn polyester yarn in the present invention is a yarn copolymerized with a difunctional phosphorus compound in an amount of 0.7 to 3.0% by weight as elemental phosphorus. Here, the polyester constituting the undrawn polyester yarn is an aromatic polyester such as polyethylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalate, etc., and a part of its acid component or a part of its glycol component is other than polyester. Dicarboxylic acid components such as isophthalic acid, 5-sodium sulfoisophthalic acid, diphenoxyethanedicarboxylic acid,
Adipic acid, sebacic acid components, etc., or other glycol components such as diethylene glycol, propylene gelicol, trimethylene glycol, tetramethylene glycol, neopentyl glycol, neopentyl glycol, 1,4-cyclohexanejetanol, diethylene glycol, polyethylene Copolymerized polyester fibers substituted with glycol, bisphenol A components, etc. may also be used.

The undrawn polyester yarn copolymerized with a bifunctional phosphorus compound in the present invention can be obtained by copolymerizing the following phosphorus compound in the polyester manufacturing process. The bifunctional phosphorus compound to be copolymerized is a phosphorus compound having two ester-forming functional groups, and includes phosphonates represented by formula (I>, phosphinates represented by formula (I[>), or formula ('I) Examples include phosphine oxyto represented by

♀ R+-P-OR3(I) ♂R2 R1-9 △IR4(II> R2 5R6 (In the formula, R1 and R5 are the same or different groups, and represent an alkyl group having 1 to 18 carbon atoms) , R2, R
3 are the same or different groups and each has 1 carbon number
~18 alkyl group or hydrogen atom, A represents a divalent or trivalent organic residue, R4 represents carboxyl, R6 forms a ring with A2 via the carboxyl group or its varnishing group Represents a divalent ester-forming functional group. ) Preferred specific examples of the phosphorus compound represented by formula (I>) include dimethyl phenylphosphonate, diphenyl phenylphosphonate, etc. Preferred specific examples of the phosphorus compound represented by formula (II) include (2-carboxyethyl )
Methylphosphinic acid, (2-methoxycarbonylethyl)methylphosphinic acid, (2-carboxyethyl)phenylphosphinic acid, (2-methoxycarbonylethyl)phenylphosphinic acid, (4-methoxycarbonylphenyl)phenylphosphinic acid, ( 2-(β
Examples include ethylene glycol ester of -hydroxyethoxycarbonyl)ethyl)methylphosphinic acid. Preferred specific examples of the phosphorus compound of formula (I) include:
(1,2 dicarboxyethyl) dimethylphosphine oxyto, (2,3 dicarboxyprobyl) dimethylphosphine oxyto, (1,2 dime]-xycarbonylethyl phosphine oxyto, (2,3 dimethoxycarbonylethyl) Dimethylphosphine oxyto, (1,2 di(β
-Hydroxy(1-oxycarbonyl)ethyl)dimethylphosphine oxyto, (2,3 di(β-hydroxyethoxycarbonyl)ethyl)dimethylphosphine oxyto, and the like.

Among these compounds, the compound of formula (n) is particularly preferred because of its good copolymerization reactivity with polyester and its low scattering during the polymerization reaction. Among the(
Ethylene glycol ester of 2-(β-hydroxyethoxycarbonylphinic acid is preferred.

The polyester fiber needs to be copolymerized with a bifunctional phosphorus compound in an amount of 0.7 to 3.0% by weight as a phosphorus element,
Particularly preferably 0.9-2.

It is 0% by weight. In the case of 0.7% by weight of non-vortex, the flame retardant performance of the obtained fiber is insufficient, and even if the desired flame retardancy can be imparted by post-processing, the amount of post-processed flame retardant attached will be insufficient. In many cases, a practical texture cannot be obtained.

Furthermore, if the amount of phosphorus element in the polyester fiber is larger than the above range, it is not preferable because not only the physical properties of the polyester fiber are significantly reduced, but also the productivity in producing the copolyester is reduced.

The phosphorus element amount in the present invention refers to the phosphorus element amount measured by a colorimetric method. There are no particular restrictions on the method of adding the phosphorus compound, but it may be added after mixing with ethylene glycol or reacting with ethylene glycol. The addition time may be at any stage from before the transesterification reaction or esterification reaction to the end of the polymerization reaction, but it is preferably added before the polymerization reaction due to good operability and fewer side reactions.

Further, a drawn yarn can be obtained by successively applying the following method. The method for spinning polyester copolymerized with a phosphorus compound is not particularly limited. The fiber cross section may be circular or non-circular, and the spinning speed is generally 700-20007 rL/min or 2000-4000 rL/min, which is said to be the POY region.
71'L/min Te too.

It is preferable to draw the undrawn polyester yarn at a high temperature within a range that does not cause superdraw. 60~ for liquid bath stretching
85°C is suitable.

The heat treatment temperature after stretching is Tc-20≦T1.
It is necessary to satisfy (°C)≦TC+20. Preferably, TO-10≦T1 (°C)≦TO+10. (Here, Tc is Parkin E1mer DSC.
-4 to heat up the non-oriented polymer at a heating rate of 16°C/min.
The peak temperature of exotherm corresponding to crystallization (°C
). ) This heat treatment is important in order to lower the shrinkage rate of the polyester fiber and at the same time make the Young's modulus as high as possible. If T1 is lower than Tc-20 (°C), the shrinkage rate of the polyester fiber will not be sufficiently reduced or Tc
If the temperature is higher than +20 (°C), the fibers begin to partially soften, resulting in interfiber fusion, which is not preferable.

At this time, the elongation ratio needs to be 0.98 to 1.02.

In other words, by performing heat treatment in a relaxed state within 0.02 or elongated within 0.02, the desired strength can be achieved.
The shrinkage rate can be obtained. The preferred elongation rate is 0.99
~1.01. If the elongation rate is less than 0.98, the shrinkage rate will be lowered, but the strength will be lowered, and at the same time, the state of contact with the heating element will be non-uniform, and non-uniformity in physical properties will become apparent, which is not preferable. On the other hand, if the elongation rate exceeds 1.02, the shrinkage rate will not decrease sufficiently, which is not preferable. Here, the elongation rate is the value obtained by dividing the yarn speed after heat treatment by the yarn speed before heat treatment, and when this value is 1.00, it is constant length, and when it is less than 1.00, it is relaxed.
Exceeding 1.00 means expansion.

The heat treatment time is preferably 2 seconds or more in order to obtain a sufficient effect. More preferably, the time is 3 seconds or more.

When mechanically crimping the fibers following heat treatment, a two-dimensional mechanical crimp can be applied, for example with a stuffer box. At this time, it is preferable to heat the fiber bundle using hot air, steam, hot water, etc., since this improves the crimp durability and reduces the shrinkage rate.

It is necessary to heat-relax the crimped fibers according to equation (2).

T1-70≦T2('C)≦T1-20...(2) Preferably, T1-60 T2('C)≦T1-25 More preferably, T1-65≦T2(°C )≦T1-30.

T1-20 ('C) had a lower shrinkage rate due to heat treatment than T1-70 ('C), whereas T1-20 ('C)
If it is higher than , the shrinkage rate decreases, but the decrease in fiber physical properties, especially the decrease in strength, the decrease in Young's modulus, and the decrease in crimp are undesirable.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Note that parts in the examples are parts by weight.

A: Intrinsic viscosity of polymer O-chlorophenol is a value measured at 25°C as a solvent.

B. Dry heat shrinkage rate Apply a load of 0.47 per denier of single yarn and increase the sample length i
After measuring o, the sample is treated in a hot air constant temperature bath at 180°C for 20 minutes. After cooling, a load of O, IJ per denier is applied again to measure the sample length Ω1, which is calculated using the following formula.

Dry heat shrinkage rate (%) = (Ω0-91)/ΩQX100C9
Flame retardancy evaluation■ "45° coil method (1)" is JIS L-1091
Measured according to method D.

■[45°] Ile method (2)” is JIS L-1091
The test was carried out in accordance with Method D, but the coil used was one with a pitch of one shoe. By using a 1M pitch coil, there is no extinguishment caused by the phenomenon of polyester melting and falling and carrying away the flame, making it possible to evaluate the self-extinguishing ability.

D. Texture A fabric made in the same manner as in the example using ordinary polyethylene terephthalate fibers that do not contain a large amount of phosphorus, and a fabric made in the same manner as in the examples using a spun yarn composed of ordinary polyethylene terephthalate fibers and cotton. The stiffness of the fabrics was evaluated in the following three grades based on the feel of the fingers, compared with the fabrics prepared in

◎ Equivalent.

○ Slight hardness is felt.

× Hardness is clearly felt.

F, phosphorus content Measured by colorimetric method.

Examples 1 to 7 and Comparative Examples 1 to 5 (A) Polyester production method Bis-β-hydroxyethyl terephthalate and its low polymer obtained by direct esterification with terephthalic acid and ethylene glycol were added to 100 parts of (2-( Ethylene glycol ester of β-hydroxyethoxycarbonyl)ethyl)methylphosphinic acid as phosphorus element content 0.80
and 0.03 parts of antimony trioxide, further added 0.30 parts of titanium dioxide, and heated at 250'C.
At the same time, the temperature of the reaction system was raised from normal pressure to 285°C in 30 minutes. The reaction was carried out by maintaining this temperature and low pressure until reaching .71. (Polymer) Polymerization reaction was carried out under the same conditions as (Polymer) except that the amount of phosphorus element was changed to 1.50 parts during polymer production. do the
A polymer with an IV of 0.72 was obtained. (Polymer ■) (B) Polyester yarn spinning method The obtained polymers (I) and (II) were heated under reduced pressure at 160'C.
Dry for 0 hours, then spin at a spinning speed of 285°C14
1500ffl/min using 001-1 circular hole cap
An undrawn yarn was obtained by spinning at a speed of .

Then, the undrawn yarn made of polymer (I) was drawn at a liquid bath temperature of 79° C., 13.45 times, and the undrawn yarn made of polymer (II) was drawn at 74° C., 13.5 times. Following the stretching, heat treatment using a hot roller and relaxation heat treatment were performed under the conditions listed in Table 1. Following the relaxation heat treatment, a finishing oil was applied and the fibers were cut into a fiber length of 38#.

The physical properties of the obtained short fibers were as shown in Table 1. Examples 1 to 7 had good strength and elongation, and the dry heat shrinkage rate at 180°C also satisfied the target of 20% or less.

In particular, the dry heat shrinkage rates at 180'c of Examples 1, 2, and 3.6 were 15% or less, which was sufficiently satisfactory.

In Example 7, yarn was spun under the same conditions as in Example 5 except that the heat treatment temperature was changed to 182°C. The texture was good without any roughness or hardness.

On the other hand, in Comparative Example 1, the fibers were fused to the hot roller and cut during the first heat treatment. Comparative Examples 2 and 3 could be heat treated without any trouble, but the dry heat shrinkage rates at 180'C were as high as 22.2% and 20.6%, respectively.

Comparative Example 4 had an average dry heat shrinkage rate of 19.
Although the target was met at 1%, the shrinkage rate, strength, and elongation of each single fiber were extremely variable, making it unusable.

Comparative Example 5 was yarn-spun under the same conditions as Example 5 except that the elongation rate during heat treatment was changed to 1.04, resulting in a dry heat shrinkage rate of 2.
It was 0.8%, which was large, and the texture was rough and hard.

On the other hand, using these single fibers, spun yarn was made by the usual method, made into a plain weave with a basis weight of 250y/Td, and each yarn was woven at 180°.
C. Table 1 shows the texture and flame retardancy evaluation results of the fabric after heat setting at a fixed length for 1 minute, washing and drying the fabric.

(The following is a blank space) [Effects of the invention] Although the fibers produced by the method of the present invention have sufficient flame retardancy, the flame retardance cannot be avoided by fibers made of polymers with a high copolymerization rate of bifunctional phosphorus compounds. It was possible to prevent high shrinkage rates and to greatly soften the texture of the product without using special equipment.

Claims (1)

[Claims] The bifunctional phosphorus compound has a phosphorus element content of 0.7 to 3.
A polyester drawn yarn copolymerized with 0% by weight was prepared using the following formula:
At a temperature T_1 that satisfies 1〉, the elongation rate is 0.98 to 1.0.
After heat treatment in step 2, mechanical crimping was performed, and then the following formula <2>
A method for producing flame-retardant polyester fibers, characterized by carrying out a relaxation heat treatment at a temperature T_2 that satisfies the following. Tc-20≦T_1(℃)≦Tc+20...<
1>Tc-70≦T_2(℃)≦Tc-20...<
2> (Tc is the crystallization temperature of unoriented polyester)