JPH0726304B2 - Polyurethane extra-fine elastic fiber non-woven fabric - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a polyurethane ultrafine elastic fiber nonwoven fabric.

[Prior Art] Various proposals have hitherto been made on nonwoven fabrics made of various polyurethane elastic fibers.

For example, Japanese Unexamined Patent Publication (Kokai) No. 52-81177 proposes a nonwoven fabric made of polyurethane elastic fibers obtained by dry spinning. However, since this is a dry-spinning process, fibers with a normal fineness cause strong sticking between fibers, resulting in poor opening, and the nonwoven fabric made from this has a hard texture, and its appearance and feel are similar to those of polyurethane film. This gives a completely different appearance and feel to the non-woven fabric.

On the other hand, in JP-A-59-223347, a filament obtained by melt-spinning a thermoplastic polyurethane and jetting a high-temperature gas stream and thinning the filament is not substantially focused, and laminated into a sheet-like filament. There has been proposed a polyurethane elastic fiber nonwoven fabric in which the contact points are joined by the filament itself. Here, the melt-spun polyurethane elastic filament does not stick to many parts like dry spinning and forms a nonwoven fabric that is not substantially bundled, so that it has flexibility, stretchability, and breathability. That is.

[Problems to be Solved by the Invention] However, in general, polyurethane is extremely active and unstable at a high temperature such as melt spinning, so that it is stable during melt spinning, particularly when a high-speed air stream is jetted to produce fine fibers. It is difficult to perform uniformization, and it is extremely difficult to obtain a non-woven fabric with little sticking and substantially no fiber sticking and sticking. Above all, it is impossible to substantially eliminate the convergence of fibers.

That is, when a polyurethane synthesized using a polyether polyol as a soft segment component is used, thermal decomposition in the molten state is severe, the elastic properties of the polyurethane are significantly deteriorated, and the stretchability for practical use is lost.

Also, when polyurethane synthesized using polyester polyol as a soft segment component is used, it has excellent thermal decomposition resistance under melting as compared with polyurethane synthesized using polyether polyol as a soft segment component, but compared to ordinary polymers. Then, the degree of polymerization during melt spinning is greatly reduced, the durability (especially hydrolysis resistance) of the ultrafine elastic fiber nonwoven fabric is further reduced from its original performance, and the elastic performance is also reduced, making it practically unusable. .

The present invention has been achieved as a result of earnest studies in view of such conventional problems.

The object of the present invention is to have a sufficiently good tactile sensation and flexibility without substantially eliminating the bundling between fibers.
It is intended to provide a polyurethane ultrafine elastic nonwoven fabric having stretchability, moisture permeability and waterproof property, and excellent in durability of these various performances.

[Means for Solving the Problems] According to the present invention, the above object is to melt and extrude thermoplastic polyurethane from a spinning hole, and at the same time, to eject a high-temperature high-speed gas from a gas discharge hole provided adjacently to provide an ultrafine particle. With a chemical fiber flow,
In a polyurethane ultra-fine elastic fiber nonwoven fabric in which this is collected in the form of a sheet, the thermoplastic polyurethane is 3-methyl-1,5-pentanediol as a polymer diol, or
Polyurethane extra fine particles obtained by using a polyester diol having an average molecular weight of 500 to 3000 obtained by reacting a mixed glycol mainly composed of this with a dicarboxylic acid, and having an average fiber diameter of 7 μm or less made of the polyurethane. This is achieved with an elastic fiber nonwoven fabric.

The thermoplastic polyurethane constituting the polyurethane ultrafine elastic fiber nonwoven fabric of the present invention is 3-methyl-1,5-pentanediol or a polyester diol having a hydroxyl group at the terminal consisting of a mixed glycol mainly composed of this and a dicarboxylic acid (hereinafter, Thermoplastic polyurethane (hereinafter sometimes abbreviated as TPU) obtained by reacting an organic diisocyanate with MPD-based PES diol)
Is.

In the above, as typical glycols used by mixing with 3-methyl-1,5-pentanediol, ethylene glycol, butanediol, hexanediol,
Examples thereof include aliphatic diols having 2 to 10 carbon atoms such as propylene glycol, neopentyl glycol and nonanediol, and polyalkylene polyols such as diethylene glycol. Each of these glycols may be used alone or in combination of two or more. It is not preferable to use too much of these diols because it reduces the effect of the present invention, and it is used within the range of 40% by weight, more preferably within the range of 20% by weight based on the glycol component in the production of the MPD PES diol. To be

As the dicarboxylic acid, aliphatic dicarboxylic acid and aromatic carboxylic acid are preferably used. Typical examples thereof include aliphatic dicarboxylic acids having 4 to 12 carbon atoms such as succinic acid, adipic acid, azelaic acid and sebacic acid, and aromatic carboxylic acids having 4 to 12 carbon atoms such as isophthalic acid and terephthalic acid. Can be mentioned.

The above polyester diol can be produced by a method similar to the known method used in the production of polyethylene terephthalate or polybutylene terephthalate, that is, transesterification or direct esterification followed by melt polycondensation reaction. Its average molecular weight is 600-300
Desirably, it is in the range of 0, preferably 800-2000.
If the molecular weight is too small, the elastic properties of the polyurethane obtained by reacting with an organic diisocyanate at the time of melting are deteriorated, and it becomes easy to microfine by jetting a high-temperature high-speed gas simultaneously with melt spinning, but the obtained polyurethane ultrafine Elastic properties of elastic nonwoven fabric, that is, the elasticity is reduced, heat resistance,
The low temperature properties are also significantly reduced. On the other hand, if the molecular weight is too large, it is not possible to form an ultrafine polyurethane fiber flow because it is extremely difficult to thin the particles by ejecting a high-temperature high-speed gas simultaneously with the melt-spinning of the polyurethane obtained by reacting with an organic diisocyanate. A polyurethane elastic fiber non-woven fabric having touch and flexibility cannot be obtained. Suitable organic diisocyanates used for producing TPU in the present invention include known aliphatic, cycloaliphatic and aromatic organic diisocyanates containing 2 or more isocyanate groups in the molecule, particularly
Diisocyanates such as 4,4′-diphenylmethane diisocyanate, P-phenylene diisocyanate, toluylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and 4,4′-dicyclohexylmethane diisocyanate Can be mentioned. 4,4'-diphenylmethane diisocyanate is preferred from the mechanical properties of the TPU obtained.

In the present invention, a suitable chain extender may be used if desired, and the chain extender may be a chain extender commonly used in polyurethanes, that is, a molecular weight of 400 containing at least 2 hydrogen atoms capable of reacting with isocyanate. The following low molecular weight compounds such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, cyclohexanediol, xylylene glycol, 1,4-bis (Β-hydroxyethoxy) benzene, neopentyl glycol, 3,3′-dichloro-4,4′-diaminodiphenylmethane, isophoronediamine, 4,4′-diaminodiphenylmethane, hydrazine, dihydrazide trimethylolpropane, Examples thereof include glycerin. Among these, 1,4-butanediol, 1,4-bis (β-hydroxyethoxy) benzene, 3-methyl-1,5-pentanediol or a mixture thereof can be most effectively used. In some cases, polymer diols such as polyethylene diol, polytetramethyllene diol, and polycaprolactone diol, and polymer diols such as polycaprolactone diol can be used within a range that does not impair the moldability.

As a method for synthesizing the polyurethane used in the present invention, a conventionally known method can be used.

(See, for example, Japanese Examined Patent Publication No. 47-34494) Next, an important point in the nonwoven fabric of the present invention is that the thermoplastic polyurethane is melt-spun and at the same time, a high-temperature high-speed gas is jetted from a gas discharge hole provided adjacently at the same time. Average fiber diameter 12μ
The following ultrafine elastic fibers may be collected in a sheet form.

That is, even if an ordinary melt-spun polyurethane is subjected to spinning winding, crimping, and carding as in the production method of cutting staples to make a non-woven fabric, it is first spun into 12
It is not possible to obtain polyurethane fibers having an average single fiber diameter of μ or less. Furthermore, polyurethane fibers cannot be crimped for carding due to their elastic properties, making nonwoven fabrics virtually impossible. On the other hand, if the high-temperature and high-speed gas is ejected from the gas discharge holes at the same time as the melt-spinning, an ultrafine fiber nonwoven fabric can be obtained even with an average single yarn diameter of 12 μm or less.

Even more importantly, the average diameter of the fibers is less than 12μ.

That is, in the case of polyurethane fibers having an extremely fine average fiber diameter of 12 μ or less, even when the bundles or sticking of the single fibers are not substantially resolved when the fibers are made into ultrafine fibers by high-temperature and high-velocity gas ejection, the resulting fiber aggregate is obtained. This is because the polyurethane ultrafine elastic fiber nonwoven fabric as described above exhibits a warm and good touch peculiar to the fibrous cloth, which is completely different from the cold touch like that of the polyurethane film, and flexibility, elasticity, and moisture permeability and waterproof property.

More preferably, the average fiber diameter is 10 μm or less. If the bundling or sticking of the single fibers is not eliminated when the average fiber diameter exceeds 12μ, the resulting nonwoven fabric will have a film-like feeling to be cooled and will be rough and hard with poor flexibility.
In addition, the moisture permeability and waterproofness are extremely deteriorated, and the waterproofness which can be put to practical use cannot be obtained.

The polyurethane ultrafine elastic fiber of the present invention is produced by a conventional melt blown method.

That is, using a melt-blown device described in JP-A-49-48921, a polyester diol composed of 3-melt-1,5 pentanediol and adipic acid having an average molecular weight of 1000, 1,4 butanediol is used. And melt-spinning the thermoplastic polyurethane obtained by melt polymerization from 4,4 diphenylmethane diisocyanate from the spinning hole,
High-temperature, high-speed air is jetted from a gas discharge hole installed adjacent to the spinning hole to make fine fibers into a sheet as an ultrafine fiber stream, for example, to a portion where the fiber stream directly hits the moving conveyor net. Collected with an exhaust system.

At this time, the distance between the spinning hole and the conveyor net is set to 10 to 30 cm in order to keep the polyurethane ultrafine elastic fiber nonwoven fabric in a good sheet form and to have a good feel, flexibility, stretchability, and breathability. Good to do. If they are separated by 30 cm or more, it becomes difficult to maintain a good sheet shape. On the other hand, if it is smaller than 10 cm, the monofilaments are strongly stuck together, and the non-woven fabric loses a good feel.

It is possible to add a light stabilizer, a pigment and other additives to the extent that they do not affect the good physical properties of the polyurethane ultrafine elastic fiber nonwoven fabric of the present invention.

Since the polyurethane ultrafine elastic fiber nonwoven fabric of the present invention has a good warm touch and flexibility, elasticity, and moisture permeability and waterproofness,
It is used in various applications that take advantage of these features. In that case, it may be used alone or in combination with other non-woven fabrics, fibers, and knits. Specifically, by taking advantage of stretchability and moisture permeability waterproofness, sports casual wear, raincoats, windbreakers, foundations, artificial leather for clothing and materials for clothing and surgical means, base cloth for compresses ,
It is used for medical hygiene materials such as adhesive plaster base cloths and diaper covers.

Examples The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. Various physical property values were measured under the following method conditions.

Strength and elongation: sample width 2.5 cm, sample length 10 cm, pulling speed 3
0cm / min Elongation recovery rate: sample width 2.5cm, sample length 10cm, pulling speed 10c
100% elongation at m / min, immediately recovering to original length at the same speed,
The residual elongation is calculated and calculated from this.

Bending: 2.5 cm sample width, 45 ° cantilever method (JIS-L109
6) Water resistance: According to JIS-1092B method.

Water vapor transmission rate: According to JIS-Z-0208.

Tactile sensation: Touch the surface of both sides of a 20 cm x 20 cm sample with your hand to judge the feeling.

Example 1 Polyester diol having an average molecular weight of 1000 and comprising 3-methyl-1,5-pentanediol and adipic acid, 1,
Melt-polymerization from 4-butanediol and 4,4'-diphenylmethane diisocyanate gave polyurethane having a nitrogen content of 4.0% by weight.

In the meltblown device described in JP-A-49-48921, etc., spin holes having a diameter of 0.3 mm are arranged in a row with a 1 mm pitch, and a slit-shaped gas discharge hole having a thickness of 0.25 mm is provided on both sides thereof. , Melt temperature of the above polyurethane 250 ℃
Then, it was discharged at 0.20 g / min per spinning hole, and heated air at 260 ° C. was jetted from the slit-shaped gas discharging hole at a pressure of 1.5 kg / cm ² gauge to perform melt-blown. At this time, the jetted fiber flow was collected on a belt conveyor running 23 cm below the spinning hole to obtain a polyurethane ultrafine elastic fiber nonwoven fabric.

The polyurethane non-woven fabric formed a good sheet shape only by being collected. Scan this non-woven fabric with a scanning electron microscope.
Observed at 0 times magnification, the average fiber diameter was 8μ, and although the fibers were found to be bundled, the physical properties of the non-woven fabric were as follows: -Basis weight: 57 (g / m ² ) -Strength: 1.6 (kg / 2.5cm) -Elongation: 290 (%)-Feeling: Fiber warm feeling.

・ Elongation recovery at 100% elongation: 91 (%) ・ Bending flexibility: 31 (mm) ・ Water pressure resistance: 400 (mmH ₂ O) ・ Water vapor transmission rate: 9050 (g / m ² / 24hrs) Good feel and flexibility It had elasticity, elasticity, and moisture permeability and waterproofness.

This non-woven fabric was attached to the back of a stretchable knitted fabric in the two horizontal directions to create a sports casual shirt, which was found to have both good tactile feel, stretchability and moisture-permeable waterproofness. .

When this non-woven fabric was immersed in warm water at 90 ° C. for 5 days, the strength and elongation retention before and after the immersion were evaluated to evaluate the durability, and the retention was 90% or more, which was extremely good.

Comparative Example 1 In melt-blowning the same polyurethane as in Example 1 with the same melt-blowing apparatus as used in Example 1, all were changed except that the discharge rate per spinning hole was changed to 0.5 g / min and the heating air pressure was changed to 0.9 kg / cm. The conditions were the same as in Example 1.

The polyurethane non-woven fabric obtained under these conditions was formed from fibers having an average fiber diameter of 14μ, and it was confirmed that the fibers were bundled together.

The physical properties of this non-woven fabric are as follows: ・ Basis weight: 110 (g / m ² ) ・ Strength: 0.7 (kg / 2.5cm) ・ Elongation: 300 (%) ・ Tactile sensation: fibrous but rough feeling .

・ Elongation recovery at 100% elongation: 92 (%) ・ Bending flexibility: 65 (mm) ・ Water pressure resistance: 80 (mmH ₂ O) ・ Water vapor transmission rate: 10200 (g / m ² / 24hrs) Coarse texture The water resistance was also small and the practical value was poor.

Comparative Example 2 3-methyl-1,5 as polyurethane in Example 1
A polyester diol having an average molecular weight of 500, consisting of pentanediol and adipic acid, 1,4 butanediol and
Melt blown was carried out under exactly the same equipment and under the same conditions except that a melt-polymerized product of 4,4'diphenylmethane diisocyanate was used to obtain a polyurethane ultrafine fiber nonwoven fabric.

The nonwoven average fiber diameter properties of Atsuta nonwoven is 8μ is a as follows, - the mass per unit area: 58 (g / m ²⁾ · Strength: 1.1 (kg / 2.5 cm) - Elongation: 130 (%) -Feeling: A warm feeling that is fibrous.

・ Elongation recovery at 100% elongation: 85 (%) ・ Bending point: 30 (mm) ・ Water pressure resistance: 420 (mmH ₂ O) ・ Water vapor transmission rate: 7500 (g / m ² / 24hrs) Poor elasticity Tonatsuta.

When this non-woven fabric was dipped in warm water at 90 ° C for 5 days, the strength before and after dipping, the elongation retention rate, and the durability centering on hydrolysis resistance were evaluated, and the retention rate was 44% or more. It was.

Comparative Example 3 In Example 1, as the polyurethane, 3-methyl-1,
Melt blown under the same conditions and under the same conditions, except that a polyester diol consisting of 5-pentanediol and adipic acid with an average molecular weight of 5000 was melt-polymerized from 1,4 butanediol and 4,4'-diphenylmethane diisocyanate. It was However, in this case, the polyurethane discharge flow almost cuts in the vicinity of the spinning hole, and sufficient thinning and ultrathinning were not performed, and it was not possible to obtain a polyurethane ultrafine elastic fiber nonwoven fabric.

Comparative Example 4 Melt blown was attempted in the same apparatus and under the same conditions as in Example 1, except that polytetramethylene ether glycol having an average molecular weight of 1100 was melt-polymerized in place of the polyester polydiol of polyurethane.

However, in this case, the thermal decomposition of polyurethane was severe in the molten state, and it was difficult to perform stable melt blowing. Although it lacked stability, it could not be put to practical use even if it was collected in a sheet form, and it was poor in mechanical properties such as elasticity.

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Claims (1)

[Claims] 1. A polyurethane ultrafine elastic non-woven fabric in which a thermoplastic polyurethane is melt-spun from a spinning hole, and at the same time, a high-temperature high-speed gas is jetted from a gas discharge hole provided adjacent to the thermoplastic polyurethane to collect it in a sheet form as an ultrafine fiber stream. The polyurethane was obtained by using a polyester diol having an average molecular weight of 600 to 3000 obtained by reacting 3-methyl-1,5-pentanediol as a polymer diol or a mixed diol mainly containing this with a dicarboxylic acid. Thermoplastic polyurethane with an average fiber diameter of 12μ
The following is a polyurethane ultrafine elastic fiber non-woven fabric characterized by having good touch, flexibility, elasticity, moisture permeability and water resistance, and excellent durability of the performance.