JPH038855A - Production of pliant elastic nonwoven fabric having high stretchability - Google Patents

Abstract

PURPOSE:To obtain a flexible elastic nonwoven fabric having high stretchability by heating and melting a polyester-based elastomer, discharging the resultant melt through spinneret holes, accompanying a high-speed fluid therewith, a jetting the melt, depositing, collecting the resultant yarn in the form of a sheet and subjecting the sheet to joining treatment. CONSTITUTION:A polyester-based elastomer composed of preferably 80-40% polybutylene terephthalate and preferably 20-60% polytetramethylene glycol is heated, melted and discharged through spinneret holes at a temperature >=40 deg.C higher than the melting point of the above-mentioned elastomer, accompanied with a high-speed fluid at >=1000m/min speed and >=30 times draft ratio and then jetted. The resultant yarn having >=30% stretch elastic recovery ratio is deposited, collected preferably mixed with a fibrous binder composed of a thermoplastic polymer having a melting point >=20 deg.C lower than that of the aforementioned elastomer and thermally melted to joint the yarn. Thereby, an elastic nonwoven fabric suitable for cushions, building and bedding material, etc., is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a manufacturing technology for a novel nonwoven fabric made of a polyester-based elastic polymer and exhibiting flexibility and high stretchability. The present invention relates to a method for producing an elastic nonwoven fabric made of a polyester elastomer containing polytetramethylene terephthalate as a main component, which is highly flexible, exhibits a high degree of recovery from repeated stretching, and has excellent morphological stability.

[Prior Art] A variety of nonwoven fabrics have been proposed and are commercially available and put into practical use in many fields, but most of these nonwoven fabrics are made from inelastic polymers such as polyamide, polyester, and polyacrylic. It is a nonwoven fabric made of fibers that do not have rubber elasticity, and there is no known nonwoven fabric comparable to knitted fabrics made of fibers that exhibit high elasticity such as polyurethane.

In recent years, attention has been focused on the fact that polyester copolymers consisting of polybutylene terephthalate and polytetramethylene glycol exhibit rubber elasticity. An attempt has been made to use a film as a substitute for a net-like nonwoven fabric by widening and spreading it (Japanese Patent Application Laid-Open No. 55-98956). however,
This net-like nonwoven fabric is a fibrillar fiber whose constituent fibers do not have a fixed thickness, shape, or fiber physical properties,
A cross section of the film that has not been completely split remains, exhibiting a scale-like luster and a poor appearance. In addition, it does not always have good tear resistance, which is one of the characteristics of nonwoven fabrics, and its properties are low. there were. Therefore, just because the reticulated nonwoven fabric has rubber-like elasticity compared to general-purpose non-rubber-like elastic fiber nonwoven fabrics, it is not necessarily satisfactory as a nonwoven fabric, and many improvements are desired in developing its uses. .

[Problems to be Solved by the Invention] The present inventors have made the most of the elastic properties of the above-mentioned polyester elastomer, and have worked hard to produce a new nonwoven fabric that reflects the appearance and performance of a nonwoven fabric.
As a result of research and development, the present invention has been discovered.

That is, the object of the present invention is to provide a nonwoven structure in which fibers having uniform fineness and cross-sectional shape are not substantially joined along the length of the nonwoven fabric, similar to conventionally known inelastic nonwoven fabrics. An elastic nonwoven fabric having a uniform and stable structure formed by opening and laminating fibers, and in which the elastic properties of the polyester elastomer constituting the fibers are substantially reflected directly in the nonwoven fabric, and further features thereof. In addition to the fineness and cross-sectional structure of the nonwoven fabric, by appropriately changing the density of the constituent fibers, it has characteristics that suit the purpose of use, and can be used to create fabrics such as general-purpose inelastic nonwoven fabrics and knitted fabrics, or other molded products. An object of the present invention is to provide a method for commercially producing elastic nonwoven fabrics with good reproducibility, which can provide a variety of products by combining the following methods.

[Means for Solving the Problems] The method for producing a flexible and highly stretchable elastic nonwoven fabric of the present invention that achieves the above object uses a polyester elastomer containing polybutylene terephthalate and polytetramethylene glycol as main components. The polyester elastomer is heated, melted, and discharged from the spinneret at a temperature of 40°C or more above the melting point of the polyester elastomer, and the discharged multifilament yarn is heated and melted using a high-speed fluid of approximately 1000 m/min or more at a draft rate of 30 times or more. to form a yarn with an elongation elastic recovery rate of at least 30%.Then, the yarn is deposited and collected in a sheet form, and the filaments constituting the sheet are further This is a method for producing a flexible and highly elastic nonwoven fabric characterized by performing a bonding treatment.

The elastic nonwoven fabric obtained by the method of the present invention contains polybutylene terephthalate (also referred to as polytetramethylene terephthalate, hereinafter abbreviated as PBT) and polytetramethylene glycol as elastic polymers forming constituent fibers. (hereinafter referred to as PTMG) is a polyester-based varnish drama whose main component is a polyester varnish with an elongation elastic recovery rate of at least 30%, which is spread without being substantially joined along its length. The filaments are laminated, and the laminated body is joined at the points of contact or intersection of the constituent filaments.

[Function] Hereinafter, the present invention will be explained in more detail while also explaining the structure of the elastic nonwoven fabric produced by the method of the present invention.

The polyester elastomer used in the present invention is PBT
It is a polyester-based copolymer exhibiting rubber elasticity containing as main components PTMG and PTMG.
As described in Japanese Patent Publication No. 19638 and Japanese Patent Publication No. 55-27097, it is a copolymerized polyester consisting of PBT and polytetramethylene glycol, with terephthalic acid as a dicarboxylic acid component and butanediol as a diol component. about 90-20%, preferably 80-4
0% PBT and about 10-80%, preferably 20-6
It is preferable to use a copolymer consisting of 0% PTMG. In addition to these main components, various copolymerization components such as isophthalic acid, adipic acid, and diethyleglycol can be copolymerized as long as the rubber elasticity of the resulting polyester copolymer is not impaired. , also coloring, gloss, weather resistance,
For the purpose of improving heat resistance, etc., small amounts of pigments, matting agents, weathering/heat resistant agents, etc. can be added.

In general, among polyester copolymers that exhibit rubber-like elasticity, those with relatively long soft segments can be coated on woven or nonwoven fabrics by extrusion molding or calendar processing. It is difficult to form multifilament yarns that are not joined to each other, and fiber forming properties can be improved by making the hard segments longer than the soft segments.
In this case, the rubber elasticity of the resulting fibers is inevitably reduced. In addition, as is known from polyurethane elastic fibers, fibers with rubber elasticity are not easy to spin, knit, or weave compared to ordinary non-elastic fibers, but the polyester elastomer has remarkable flexibility. In order to exhibit large and pseudo-adhesive properties, it can be used not only for knitted fabrics, but also for knitted fabrics.
Even in the case of non-woven fabrics, it is difficult to spread the filament threads together.
It is difficult to form a uniform nonwoven fabric. In particular, there is a problem that fabric formation becomes difficult as the fineness decreases.

The present invention is not a nonwoven fabric made of thick denier single fibers like a normal monofilament, but a multifilament yarn that does not join (spread) over substantially the entire length of the yarn like a normal nonwoven fabric. However, this can only be achieved by employing the specific nonwoven fabric manufacturing process and conditions described below for the polyester elastomer.

Here, in the present invention, the fineness of the polyester-based nisdrama fiber constituting the nonwoven fabric is 0.1 to 30 denier (d
), preferably 0. 5 to 10 d is preferable, and the cross-sectional shape can take various shapes such as circular, deformed, hollow, etc. However, in consideration of post-processability as a nonwoven fabric, sheet formability, and elastic recovery, a circular cross-section is preferable. In addition, the number of single filaments of the multifilament yarn when forming a nonwoven fabric depends on the fineness, but is preferably at least 30, preferably 10 or less (if the single filament fineness is thick and the number of single filaments is 30 or more), A flexible and highly elastic nonwoven fabric cannot be obtained. On the other hand, if the fineness of the single filaments is small and the number of single filaments is large, it is difficult to open the yarns when forming the nonwoven fabric, preventing uniform lamination, and in either case, sheet unevenness may occur. This is not preferable because it becomes noticeable.

One important feature of the present invention is that the elongation recovery rate of the polyester copolymer fibers constituting the nonwoven fabric is at least 30% when the fibers with a trial length of about 10 cm are stretched 100% and then immediately unweighted. Preferably, it is necessary to recover at least 50% of the length, and by constructing the nonwoven fabric with fibers that exhibit such a stretch recovery rate, the elastic recovery and morphological stability of the nonwoven fabric against repeated stretching are significantly increased. In the nonwoven fabric fiber yarn of the present invention having such an elongation recovery rate, although it is made of the rubber-like elastic polymer, the constituent single fibers do not weld to each other over the length direction. Since they are separated to form a nonwoven fabric, the elasticity of the nonwoven fabric can be significantly increased.

That is, in the nonwoven fabric obtained by the present invention, the multifilament yarns are sufficiently opened to become monofilament yarns and joined at their mutual contact points or intersection points, and stress is dispersed throughout the nonwoven fabric's constituent fibers. As a result, the elasticity of the nonwoven fabric increases synergistically, and its flexibility is not lost.

Bonding of mutual contact points or intersection points of nonwoven fabric constituent fibers is
An adhesive as the third component may be applied by spraying, impregnating, etc., and bonding may be performed, but it is preferable to adhere the fibers themselves that constitute the nonwoven fabric, which is superior in terms of manufacturing and quality. More preferably, a fibrous binder made of a thermoplastic polymer having a melting point lower than that of the polyester copolymer by about 20° C. or more is mixed, and only this fibrous binder is heated and melted, so that the contact points or intersection points of the fibers are mixed. It is preferable to join part or most of the parts.

Any thermoplastic polymer may be used to form the fibrous binder, but preferably a polyester copolymer having a lower melting point by increasing the copolymerization amount of the third copolymer component in the polyester copolymer. Good. In addition, the bonding ratio of mutual contact points or intersection points of fibers is, for example, in the case of a fibrous binder, about 0.5 to 20% by weight, preferably about 2 to 15% by weight, based on the weight of the nonwoven fabric.
It is best to select an appropriate value within the range of .

The elastic nonwoven fabric obtained by the present invention can be used alone for purposes that take advantage of its excellent elasticity and flexibility, but it can also be used for various inelastic fiber products, such as polyethylene terephthalate, nylon 6.66.610, polyolefin, and polyacrylonitrile. Fiber products (knitted fabrics, net fabrics, non-woven fabrics,
It can be combined with other materials (such as paper) to make a variety of products. However, by needle punching a laminate of the elastic nonwoven fabric obtained by the present invention and a non-bonded, non-bonded fleece made of short fibers made of the inelastic polymer, the non-bonded, non-bonded fleece is integrally laminated on the elastic nonwoven fabric. The resulting nonwoven fabric is a bulky fiber fabric that maintains the excellent elasticity and flexibility of the elastic nonwoven fabric, and has significantly improved functionality as a textile product. That is, the elastic nonwoven fabric obtained by the present invention has extremely flexible constituent fibers, low stiffness or Young's modulus, and has no so-called stiffness.Moreover, due to its excellent rubber elasticity, it can be laminated with any fabric and needled. Although it is difficult to sufficiently entangle the laminated sheets in the above-mentioned non-elastic short fiber fleece, when lamination and needling are performed with the non-elastic short fiber fleece, the fleece constituent fibers are The fleece material moves to the elastic nonwoven fabric layer and is entangled in one direction to form a nonwoven fabric that reflects fabric properties such as bulkiness and rigidity based on the fleece.

Such inelastic short fiber fleece may be selected as appropriate depending on the intended use, but preferably has a fineness of 0.1.
~30d1, especially 0.5-5d, fiber length about 15-150
mm, preferably from 20 to 1,00 mm, with a basis weight of approximately 2'0
~250 g/rd, preferably 30-200 g/r
r? It is best to choose from those within the range.

The elastic nonwoven fabric obtained by the present invention, which has a nonwoven fabric structure similar to that of nonwoven fabrics made of inelastic fibers, has extremely excellent flexibility, drapability, and rubber-like elasticity, and has a texture similar to that of the various known fabrics mentioned above. , can be laminated, coated, and integrated without impairing the physical properties of the fabric, exhibits excellent followability to deformation of these fabrics, and does not destroy its nonwoven fabric structure even when subjected to strong deformation. Therefore, the elastic nonwoven fabric obtained according to the present invention can be used for cushions, construction bedding, indoor bags, bags, belts, strings, backings, etc. by utilizing its excellent elasticity, molding, adhesion, and vibration-proofing properties. It can be used for a wide range of purposes, including clothing, such as filling and interlining.

Such a highly elastic and highly stretchable nonwoven fabric according to the present invention,
The polyester copolymer is heated and melted and discharged from the spinneret hole at a temperature higher than the melting point of the copolymer plus 40° C., and the discharged yarn is heated and melted at a draft rate of at least 30 times. By ejecting it accompanied by a high-speed fluid of 1000 m/min or more, a thread with an elastic recovery rate of at least 30% upon elongation is formed, and then the thread is deposited and collected in a sheet form. It can be obtained industrially.

That is, the first requirement in manufacturing the nonwoven fabric of the present invention is:
If the discharge temperature is at the discharge temperature of the molten polymer and the discharge temperature is lower than the melting point of the polyester polymer plus 40°C, the discharge yarn will expand and contract while running, making continuous jetting and sheet formation difficult. Even if the jetting force of the high-speed fluid is adjusted, it is not possible to stably produce a nonwoven fabric.
It is necessary to discharge at a temperature higher than the melting point plus 40°C.

The second requirement is that the discharged yarn has a draft rate of at least 30 times, that is, a value obtained by dividing the speed of the discharged yarn to be jetted by the discharge linear velocity of the discharged yarn at the nozzle hole. When this draft ratio is smaller than 30 times, the obtained fiber yarn shows a strong elongation curve with a force elongation region, and only a yarn with a small elongation 1jBt recovery rate is obtained, which is the object of the present invention 1□4. This is undesirable because an elastic nonwoven fabric with a high degree of elasticity is not formed, and the discharged yarns tend to wobble significantly, and the formation of yarns in which the single fibers are sufficiently separated and the spinning stability are impaired.

In the present invention, the ejected fibers are accompanied by high-speed airflow, and the
Spray at a speed of 0 m or more. This requirement is achieved by surrounding the stretchable fibers with air currents so as to serve as an air guide, causing them to be accelerated and oriented. An example of a means for entraining the high-speed airflow is to place an air ejector below the spinneret to stretch and eject the fiber bundle. In another embodiment, a heated air ejection hole may be provided near the cap pore, and air and polymer may be ejected in the same direction. In either method, the fiber bundles accelerated at high speed are protected by accompanying air currents, allowing continuous and stable fiberization without abnormal expansion/contraction, twitching, or twisting. In the present invention, the injected fiber group is collected in the form of a sheet on the forming surface to produce a nonwoven fabric having a desired thickness and filament arrangement. For example, by sandwiching the jet flow between two flat plates, the filaments are arranged in the direction of the gap, and by collecting them in this state, a sheet arranged in any direction can be obtained. This sheet has high elastic recovery in the direction in which the filaments are arranged, and is suitable for cutting the sheet to make tapes, bands, and strings. In addition, to avoid anisotropy, after sufficiently attenuating the jet,
A nonwoven fabric with a random arrangement can be made by collecting on a net conveyor or collecting in a manner that does not damage the conical jet stream.

In the present invention, the sprayed fiber groups must be uniformly stacked. Practically, this means is 1/1 of the fiber ejection speed.
By taking measures such as moving the collection surface at a speed of 0 or less, a uniform nonwoven fabric with many layers stacked on top of each other can be obtained. Under suitable conditions, the variation in weight of a large number of sheet pieces cut into 10 square pieces is determined as a measure of uniformity.
A coefficient of variation of 15% or less is practically suitable.

When the nonwoven fabric is cut into a tape shape and used, it is preferable that the coefficient of variation is 10% or less.

In the present invention, it is necessary that the laminated fibers be bonded at the mutually contacting portions, but under certain conditions, the bonding state can also be partially achieved by selecting the distance from the injection port to the collection surface. can be obtained. Specifically, in addition to meeting the specific conditions, for example, increasing the spinning temperature, increasing the filament fineness, increasing the number of filaments, increasing the jetting speed, making the filament fineness vary, and It lowers the melting point of the material, increases the temperature of the accompanying air flow, etc. Generally, the shorter the collection distance is within 1.5 meters, the higher the bonding effect becomes.1 If the collection distance is short If the spread of the jet is small and it is difficult to form a wide sheet, or if the bond during collection is weak, the collection sheet is passed through a heated atmosphere or heated and pressurized.

Generally, treatment at a temperature of 10° C. or lower than the melting point of the copolymer is preferred. In addition, if the above-mentioned heat treatment means is intense and imposes practical limitations, another embodiment may be a method in which adhesives such as various emulsions, solutions, powders, etc. are dispersed in the fiber sheet. Alternatively, as yet another embodiment, a method may be taken in which fibers from another low melting point polymer are mixed to form a nonwoven fabric, and then the mixed low melting point fibers are melted.

[Effects] The nonwoven fabric obtained by the method of the present invention described above is preferably stretched several times to a region where the contact portions of the fibers are partially or mostly bonded, and exhibits elastic recovery, and then loosened. It has an excellent feature of not damaging the nonwoven fabric shape even if it is repeated several times or more.

The nonwoven fabric thus obtained is advantageous because it can be subjected to relaxation or constant length heat treatment to increase its elongation elastic recovery rate and maximum elongation rate.

[Example] Example 1 A copolymer with a melting point of 147°C was prepared by copolymerizing polybutylene terephthalate/isophthalate with a molar ratio of terephthalic acid and isophthalic acid of 70:30 and 50 parts of polytetramethylene glycol with a molecular weight of 1000. It was dried in a vacuum at 110° C. for 12 hours, and melted and discharged at 220° C. through six 0.3 mm pores at a rate of 0.5 g per minute per single hole. This yarn was introduced into an air aspirator placed 60 cm below the nozzle and injected with pressurized air of 3 kg/crtr G.

The thickness of the single fiber obtained at this time was 2.8 denier, the spinning speed was 1600 m/min, and the recovery rate when relaxed after 100% elongation was 84%.

In addition, the draft rate at this time is determined by the formula: [Draft rate = Spinning speed / Discharge speed of the entire spout. (cc/min)/discharge hole area (car)], and the draft rate is 205.

These fibers were collected on a 30-mesh wire mesh, and 50g
/rrf nonwoven fabric was obtained. This non-woven fabric has a surface temperature of 130
The joints of the fibers were joined by placing them in a calender at ℃.

The obtained sheet was further heat-treated at 135° C. in an unrestricted state. This sheet could be repeatedly stretched by 50% without destroying its structure, and instantly recovered by 70% when the tension was released. It was confirmed that some of the fibers in the sheet were in contact with each other at the surface.

This sheet was effective when used for various base materials, such as synthetic leather and clothing lining materials, which require elasticity.

Example 2 The ratio of polybutylene terephthalate to isophthalate is 7
A copolymer having a melting point of 164° C. and containing 20 parts of polytetramethylene glycol was spun at a spinning temperature of 185° C. (comparative example) and 20° C. by the method of Example 1.
Nonwoven fabrics were made at different temperatures: 0°C (comparative example) and 230°C (inventive example). When the temperature was 185 DEG C., the filaments on the air aspirator vibrated extremely, twisted together, and frequently broke. When the temperature was 200°C, thread breakage did not occur, but the collected nonwoven fabric contained a mixture of nonuniform fiber clumps.

In the case of 230° C., everything went well, and the obtained sheet could be stretched by 30% without destroying the tissue, and recovered by 60% when the tension was released.

Example 3 200g for the case of 230°C among the conditions of Example 2
/rrf nonwoven fabric was sampled and treated in a calender at a temperature of 150°C. This nonwoven fabric was extremely flexible and had high elasticity, withstanding 50% elongation and 70% recovery from elongation.

The stretch recovery rate of 100% of the constituent fibers was 80%.

This sheet was extremely useful in making use of its elasticity in cushioning materials, battings, interlining materials, various impregnated and coating materials, tapes, bands, and packing materials.

Example 4 Among the polymer and other conditions of Example 1, the discharge amount of the molten polymer was changed to a draft ratio of 20, 40, 100, 500, and the injection pressure of the air aspirator was set to the maximum of each. Selected and set. At a draft rate of 20, adhesion to the air aspirator and twitching of the fibers occur.
Sheet collection was not possible. Draft rate 40 and 1
In the case of No. 00, the single fibers could be stretched by 300 to 400%, and the 100% stretch recovery rate was 82% and 85%, respectively. The one with a draft rate of 500 had a single fiber elongation rate of 150% and a 100% elongation recovery rate of 85%. Calendered sheets made from these fibers, except those with a draft ratio of 20, could be stretched repeatedly by 50% without destroying the sheet structure and exhibited elastic recovery of more than 50%.

Example 5 The elastic nonwoven fabric obtained in Example 1 was mixed with 30% rayon (3 denier x 51 mm) and 70% polyethylene terephthalate staple (2.5 denier x 76 m), opened, and then passed through a carding machine. Fleece having a basis weight of 100 g/rrf was laminated, and 80 needle punches were applied every d from the upper surface of the fleece.

The obtained needle-punched nonwoven fabric was highly elastic, flexible, bulky, and had excellent shape stability.

When this nonwoven fabric was used as a padding for clothing, it had excellent heat retention without impairing the feel of the side fabric, and had excellent conformability to the human body when worn.

Claims (1)

[Claims] (1) A polyester elastomer whose main components are polybutylene terephthalate and polytetramethylene glycol is heated and melted, and discharged from a die hole at a temperature of 40°C or more above the melting point of the polyester elastomer, and the discharged multifilament is produced. Spraying the yarn with a high-velocity fluid of about 1000 m/min or more at a draft rate of at least 30 times to form a yarn with an elongation elastic recovery rate of at least 30%, and then depositing the yarn in a sheet. A method for producing an elastic non-woven fabric having flexibility and high elasticity, which comprises collecting , and then subjecting filaments constituting the sheet-like material to bonding treatment.