JPH0593315A - Method for providing copolyester fiber having shape memorizing ability with shape memory - Google Patents

Abstract

PURPOSE:To provide the subject fiber with a desired shape in excellent productivity by heat-treating specific copolyester fiber so as to satisfy a specific condition. CONSTITUTION:Copolyester fiber (preferably fiber obtained by copolymerizing an aromatic polyester segment with an aliphatic polyester segment in a proper ratio) having >=150 deg.C melting point, >=2.5g/denier strength of single fiber and shape memory ability is heat-treated in such a way that the formula B-A>=5 [A is degree of crystallization (%) of the copolyester before heat treatment to provide shape memory; B is degree of crystallization (%) of the copolyester after the heat treatment] to provide the fiber with the objective shape memory.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for imparting shape memory to a copolyester fiber having a shape memory ability.

[0002]

2. Description of the Related Art In recent years, synthetic resins having shape memory ability have been developed and put on the market. This resin has a large change in elastic modulus before and after the glass transition point. The function is, for example, to first form an arbitrary shape M, heat in the state of the shape M, crystallize (entanglement of crystal parts) or generate a fixed point by intermolecular crosslinking to memorize the shape. Then, an external force is applied in an atmosphere having a temperature above the glass transition point and lower than the above heating temperature to deform the shape N, and the temperature is kept below the glass transition point as it is, so that the shape N can be fixed. By further heating this above the glass transition point, it has a function of recovering the shape M without applying an external force, that is, it has a "shape memory ability".

As a resin material having a shape memory ability, a polytransisoprene resin (Japanese Patent Laid-Open No. 55-93806) is used.
No.), polynorbornene-based resin (JP-A-59-5352)
No. 8), consisting of a mixture of vinyl resin and acrylic acid resin or synthetic rubber (JP-A-63-17952).
No.) etc. are known. Further, a polyurethane-based shape memory polymer yarn (Japanese Patent Laid-Open No. 2-169713) is disclosed.

However, conventionally known resin materials have poor spinnability, have a fineness of about 1 to 3 denier, such as those used as long fibers or short fibers for spinning, and have good post-process passability, to a certain extent or more. It was almost impossible to produce high strength fibers with high productivity. Therefore, the shape-memory fiber is heat-treated under specific conditions to memorize the shape,
It has not been put to practical use yet.

[0005]

The present invention is intended to solve such a problem. That is, it is intended to provide a method for imparting shape memory to a fiber using a copolyester having a shape memory ability capable of melt-spinning a fiber having a fineness as well as a normal polyester with good productivity.

[0006]

The present inventor has arrived at the present invention as a result of extensive studies to solve the above-mentioned problems.

That is, the first invention of the present application has a melting point of 15
A method for imparting shape memory is characterized in that a copolyester fiber having a shape-memory capacity of 0.degree. C. or more and a single fiber strength of 2.5 g / denier or more is heat-treated so as to satisfy the following formula. In the second invention of the present application, a long-chain aliphatic dicarboxylic acid having 6 or more carbon atoms is copolymerized and has a melting point of 15
A gist of a shape memory imparting method is characterized in that a polyethylene terephthalate fiber having a shape memory capacity of 0 g or more and a single fiber strength of 2.5 g / denier or more is heat-treated so as to satisfy the following formula. .. B−A ≧ 5 where A: crystallinity (%) of copolyester fiber before heat treatment for imparting shape memory B: copolyester fiber after heat treatment for imparting shape memory Crystallinity (%)

The present invention will be described in detail below.

The copolyester having shape memory ability used in the present invention has the following characteristics. (a) The shape is memorized when it is crystallized in a heating atmosphere after melt molding. (b) When an external force is applied in a temperature range higher than the glass transition point and lower than the temperature at which the shape is memorized, it deforms relatively easily. (c) If the temperature is below the glass transition temperature while maintaining the deformed shape, the deformed shape is fixed. (Shape-fixing ability) (d) Furthermore, if a temperature higher than the glass transition point is applied to this without applying an external force, the shape remembered in (a) is restored. (Shape recovery ability)

The melting point of the copolyester must be 150 ° C. or higher. If the melting point is less than 150 ° C, heat set for preventing the shrinkage of fibers and high temperature dyeing become difficult, which is not practical.

The single fiber strength of the copolyester fiber is
It must be at least 2.5 g / denier. Single fiber strength
If the amount is less than 2.5 g / denier, it is not practical because the productivity and yarn quality are deteriorated due to the breakage of single fiber in the spinning process.

The glass transition point of the copolyester is preferably 80 ° C. or lower. If the glass transition point exceeds 80 ° C., the temperature required for shape recovery may be too high and not practical. When the glass transition point is about 45 ° C. or higher, the fibers used in the present invention have the same texture as ordinary polyethylene terephthalate fibers up to room temperature or body temperature, and if heated above the glass transition point, Return to the memorized state. When the glass transition point is lower than room temperature or body temperature, the temperature is higher than the glass transition point during normal use, so that the body is soft and has a property of always returning to a memorized state. Wrinkles are more difficult to use when a cloth made of the above fibers is memorized in advance at a high temperature by ironing or the like without wrinkles.

Further, the copolyester fiber used in the present invention remembers the shape in the heat treatment step in which crystallization proceeds. Here, the formula B-A is 5 (%)
If it does not meet the requirement, shape memory is not sufficiently imparted to the fiber. Here, the heat treatment temperature may be selected such that the crystallization of the copolyester fiber proceeds at a practical speed. As a standard heat treatment condition, a temperature of 20 ° C. to 150 ° C. lower than the melting point of the copolyester is several seconds to several tens of minutes.

Next, as a method for obtaining a copolyester having a shape-memory ability, a method of copolymerizing an aromatic polyester segment (hard segment) and an aliphatic polyester segment (soft segment) at an appropriate ratio to obtain a polymer Another example is a method of copolymerizing an aromatic polyester segment (hard segment) and a polyalkylene glycol segment (soft segment) at an appropriate ratio to obtain a polymer, but the former is preferable.

The aromatic polyester segment means a polyester segment having at least one aromatic ring in the polyester repeating unit, and the aliphatic polyester segment means a polyester segment in which the polyester repeating unit is composed of only an aliphatic compound. Say that.

Examples of the aromatic monomer component forming the hard segment include terephthalic acid, isophthalic acid, bisphenol A, dicarboxylic acids such as p-oxybenzoic acid, diols and hydroxycarboxylic acids.

Examples of the aliphatic monomer component that constitutes the hard segment with the aromatic monomer or the soft segment itself includes adipic acid,
Azelaic acid, dodecanedioic acid, eicosanedioic acid, ethylene glycol, butanediol, hexanediol, ε
-Dicarboxylic acids such as caprolactone, diols and oxycarboxylic acids (or lactones). Polyalkylene glycols such as polyethylene glycol and polytetramethylene glycol can also function as the soft segment component.

The hard segment is preferably a polyester having an ethylene terephthalate unit or a butylene terephthalate unit, but the ethylene terephthalate unit is most preferable in view of economy and physical properties. The soft segment is preferably a long-chain aliphatic dicarboxylic acid such as azelaic acid, sebacic acid, dodecanedioic acid, etc., and particularly an ester unit of an aliphatic dicarboxylic acid having 6 or more carbon atoms and ethylene glycol.

In the copolyester used in the present invention, it is considered that the soft segment acts as an intramolecular plasticizer to promote the crystallization of the polymer and causes the entanglement of the crystallized portions to give a fixed point. .. Even a copolyester consisting of only these hard and soft segments can be made into a polyester having sufficient shape memory capacity, but even if a molecular structure capable of intermolecular cross-linking is introduced, the rubber remembers its shape by vulcanization. Similar to the principle described above, it can function as a fixing point for fixing the shape to be memorized by cross-linking the polyester molecules at important points. Specific examples of the molecular structure capable of intermolecular crosslinking include a structure in which a monomer component having an unsaturated bond is copolymerized and an unsaturated bond is introduced into the main chain of polyester. Intermolecular cross-linking becomes possible by cleaving this unsaturated bond by an appropriate means when the shape is fixedly memorized.

Examples of monomer components which can be copolymerized with polyester and have an unsaturated bond include, for example, maleic anhydride, maleic acid, chloromaleic acid, itaconic acid, fumaric acid, citraconic acid, hettic acid, hettic anhydride, 2-
Examples thereof include unsaturated dicarboxylic acids or unsaturated diols such as butene-1,4-diol and 3-butene-1,2-diol.

Copolymerization of a polyester with a trifunctional or higher functional monomer component is also an effective means. In this case, when the shape is fixedly stored, intermolecular crosslinking can be performed by adding and reacting a crosslinking agent having a hydroxyl group or a carboxyl group of polyester, an isocyanate group, an amino group or the like.

The copolyester according to the present invention may optionally be copolymerized with other auxiliary raw materials as long as the object of the present invention is not impaired, and contains various additives. May be.

The constituent components of the monomers constituting the copolyester used in the present invention and the copolymerization ratio thereof can be selected in a wide range, but in consideration of economical efficiency, versatility, physical properties, etc. Is preferred. That is, terephthalic acid as a dicarboxylic acid is 50 to 95 mol%, preferably 60 to 90 mol%, dodecanedioic acid is 5 to 50 mol%, preferably 10 to 40 mol%, and ethylene glycol is 100 mol% as a diol. It is a polyester used in proportion. In this example, the repeating unit consisting of ethylene glycol and terephthalic acid shares the function of the hard segment, and the repeating unit consisting of ethylene glycol and dodecanedioic acid shares the function of the soft segment.

The copolyester fiber used in the present invention may be produced by the melt spinning and drawing methods as in the case of general-purpose polyester fiber. Spinning conditions and drawing conditions differ depending on the physical properties of the shape-memory polyester used, but can generally follow conventional techniques. That is, spinning may be performed using a general-purpose spinning device or a composite spinning device. The spun fiber is drawn or heat-treated continuously or in another step as required, and subjected to higher-order processing such as crimping and chemical treatment. In addition, additives such as stabilizers, fluorescent agents, pigments, and reinforcing materials may coexist during spinning.

The fiber shape of the copolyester fiber may be a round cross section, an irregular shape such as a triangular cross section, or a hollow fiber.

The obtained copolyester fiber can be formed into a spun yarn with high productivity by a conventional method, and can be subjected to a weaving / weaving process and a dyeing process in the same manner as ordinary polyethylene terephthalate.

The fibers of the present invention are polyester fibers such as ordinary polyethylene terephthalate and polybutylene terephthalate which do not have a shape memory ability, nylon fibers, rayon fibers, wool, cotton and hemp, as long as the shape memory ability is not impaired. It does not matter even if it is a mixture of synthetic fibers such as, regenerated fibers and natural fibers.

[0028]

When the shape of the copolyester fiber having a shape memory capacity is memorized by the heat treatment crystallization in which a fixed point is generated by the method of the present invention, the temperature exceeds the glass transition point. At this time, the action of returning to the original shape works, and it becomes possible to return to the original shape.

[0029]

EXAMPLES Next, the present invention will be described with reference to examples. In the examples, the characteristic values of polyester are measured as follows. (1) Intrinsic viscosity An equal weight mixture of phenol and ethane tetrachloride was used as a solvent, and measurement was performed at a temperature of 20 ° C. (2) Melting point Differential scanning calorimeter (DSC-2 manufactured by Perkin Elmer Co., Ltd.
Type) was used and the temperature was raised at a rate of 20 ° C./min.

(3) Crystallinity The density d of the fiber sample was measured at 20 ° C. by the floating method using a density gradient tube containing a carbon tetrachloride-heptane mixture. In addition, the crystallinity was calculated according to the following known equation for polyethylene terephthalate, Equation 1:

[0031]

[Formula 1]

Note that k is a constant determined by the type of copolyester having a shape memory capacity, and is a constant of the drawn cotton density of ordinary polyethylene terephthalate prepared under the same conditions and the density of a copolyester drawn cotton having a shape memory capacity. It is the difference. By the way, the density of the copolyester fiber (after stretching) obtained in Example 1 described later was 1.349, and the density of polyethylene terephthalate adjusted under the same conditions was 1.383, and in this copolyester, k = 1.383-1.349 = 0.034 ..

Example 1 Bis (β-hydroxyethyl terephthalate) obtained by the esterification reaction of terephthalic acid and ethylene glycol and 45.0 kg of its oligomer were mixed with dodecanedioic acid.
5.8kg, maleic acid 0.4kg, ethylene glycol 9.0k
g, add 26 g of tetrabutyl titanate as a catalyst,
The esterification reaction was carried out at 250 ° C. under a nitrogen gas pressure of 3.6 kg / cm ² for 2 hours. The copolymerization amount of dodecanedioic acid was 10 mol% and the copolymerization amount of maleic acid was 1.5 mol%.

The obtained esterified product was transferred to a polycondensation reactor and subjected to a polycondensation reaction at 280 ° C. and 0.4 torr for 3 hours to obtain a copolyester A. The obtained copolyester A has a glass transition point of 49 ° C, a melting point of 232 ° C and an intrinsic viscosity of 0.
It was 65.

After the chips of copolyester A were dried under reduced pressure, they were melted using an ordinary melt spinning apparatus, and the number of spinning holes was 4
Through 15 spinnerets, spinning temperature 270 ℃, total discharge 3
Melt spun at 00 g / min. After cooling the spun fiber yarn, it was taken out at a take-up speed of 1000 m / min to obtain an undrawn fiber yarn. The obtained filaments are bundled, made into a tow of 100,000 denier, and drawn at a draw ratio of 3.4 and a draw temperature of 60 ° C, and then drawn at 120 ° C.
After heat-treating with a heat drum, the crimp was applied using a push-in crimper. Subsequently, it was cut into a length of 51 mm to obtain a copolyester fiber having a single yarn fineness of 2 denier, a single fiber strength of 5.6 g / denier, and an elongation of 52%. Using this fiber, 20th spun yarn was obtained through card, drawing, roving, and spinning.

This spun yarn was woven with a design of 103 warps / inch, 87 wefts / inch, and a width of 93 cm to obtain a fabric. The degree of crystallinity of the single fibers constituting the fabric was 44%. A 40 cm square of this cloth was folded in two and heat-set at 170 ° C. for 2 minutes using a heat press machine to memorize the folds. The crystallinity of the single fibers composing the fabric after the heat setting is 5
It was 1%. Furthermore, after washing this with a home washing machine,
The fabric was hung in a drying room at 60 ° C with one side facing up and dried. When it was taken out after drying, compared to a normal polyethylene terephthalate cloth heat-set under the same conditions,
The creases that were memorized were clearly seen, and the shape memory ability was good.

Example 2 Using a cloth woven in the same manner as in Example 1, desizing and refining were performed according to a conventional method. Further, using a high-pressure beam dyeing machine, high temperature dyeing was carried out with a disperse dye and a dispersant at 130 ° C. for 1 hour to obtain a blue cloth. The degree of crystallinity of the single fibers constituting the fabric was 49%. This 40 cm square piece of fabric was folded in two and heat-set at 170 ° C. for 10 minutes using a heat press machine, and the crease was recorded. The crystallinity of the single fiber constituting the fabric after the heat setting was 58%. When the shape memory ability of the obtained blue fabric was examined by the same method as in Example 1, it was good.

Comparative Example 1 The procedure of Example 2 was repeated except that the heat setting condition was 170 ° C. for 1 minute. The crystallinity of the single fiber constituting the fabric after heat setting was 51%. Looking at the shape memory ability in the same manner as in Example 1,
The creases were unclear and the shape memory ability was insufficient as in the case of heat-set under the same conditions on ordinary polyethylene terephthalate cloth.

Examples 3 to 4 and Comparative Example 2 Copolyesters B to D were prepared in the same manner as in Example 1 except that maleic acid was not added and the copolymerization amount of dodecanedioic acid was changed. Obtained. Table 1 shows the physical properties of these copolyesters. Further, Examples 3 to 4 and Comparative Example 2 were performed in the same manner as in Example 1 except that these copolyesters were used instead of the copolyester A in Example 1 and the heat drum temperature in the stretching step was changed.
I got a spun yarn. Using these spun yarns, weaving was performed in the same manner as in Example 1 except that the iron heat set temperature for storing the folds was changed, and the shape memory ability was evaluated. The results are also shown in Table 1.

[0040]

[Table 1]

As is clear from Table 1, the shape memory abilities of Examples 3 and 4 were good, as in Example 1, and judged visually by the memory condition of the folds, but the copolymerization amount of dodecanedioic acid was In the case of Comparative Example 2, which is a copolyester fiber having many melting points and a low melting point, light fusion between fibers occurred during dyeing, resulting in a rough texture and poor shape memory ability.

Comparative Example 3 A copolyester E having an intrinsic viscosity of 0.44 was obtained by changing the polycondensation reaction time to 1.5 hours in Example 1. The glass transition point of this copolyester E is 47 ° C, and the melting point is 230 ° C.
Met. Except for using this copolyester E,
The same procedure as in Example 1 was carried out to obtain a copolyester fiber having a single fiber strength of 2.3 g / denier and an elongation of 50%. Spinning was carried out using this fiber, but since the spinning performance was poor due to the occurrence of cotton wool and yarn breakage, the subsequent tests were cancelled.

[0043]

EFFECTS OF THE INVENTION According to the present invention, shape memory can be satisfactorily imparted to a copolyester fiber having a shape memory ability. According to this method, once a woven or knitted fabric, a non-woven fabric, or a fiber laminated web is heat-treated and shaped (shape memory), even if it loses its shape during use, it returns to its original shape by light heating. That is, according to the method of the present invention, even if the memorized shape is destroyed during use or by washing, the original shape is restored by light heating above the glass transition point. Therefore, it can be applied to bedding materials such as futon side cloths, bedding materials such as pillow covers, or clothing such as cuter shirts, polo shirts, trousers, ties, etc., to prevent wrinkles and creases by press working for a long time, or to make cloth centering materials and hat materials. It can be applied to and promote the shape prevention effect. It can also be applied to piles such as mockets and carpets to bring about the effect of correcting pile collapse. Furthermore, it is used as a non-woven fabric interlining or quilting batting, and even if it loses its shape, it recovers its shape by light heating, its shape-retaining and heat-retaining effects last long, and crimps are memorized in the state of short fibers. It can also be used as futon cotton or cushion material, and even when it is used, it can be restored to its original bulky state with a light heating.

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Claims (2)

[Claims] 1. A method for imparting shape memory, which comprises heat-treating a copolyester fiber having a shape memory capacity of 150 g or more and a single fiber strength of 2.5 g / denier or more so as to satisfy the following formula. .. B−A ≧ 5 where A: crystallinity (%) of copolyester fiber before heat treatment for imparting shape memory B: copolyester fiber after heat treatment for imparting shape memory Crystallinity (%) 2. A polyethylene terephthalate fiber copolymerized with a long-chain aliphatic dicarboxylic acid having 6 or more carbon atoms, having a melting point of 150 ° C. or more and a single fiber strength of 2.5 g / denier or more and having a shape memory capacity A shape memory imparting method, characterized by performing heat treatment so as to satisfy the formula. B−A ≧ 5 where A: crystallinity (%) of copolyester fiber before heat treatment for imparting shape memory B: copolyester fiber after heat treatment for imparting shape memory Crystallinity (%)