JP2821036B2 - High elasticity nonwoven fabric and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic elastomer nonwoven fabric. More specifically, low modulus, high elasticity,
The present invention relates to a nonwoven fabric made of a thermoplastic elastomer which has excellent weather resistance and is particularly suitable for applications requiring stretchability with a compress base fabric or the like.

[0002]

2. Description of the Related Art There has been a great demand for stretchable non-woven fabrics in the non-woven fabric industry, and various products have been proposed. For example, as a compress base fabric, there is an elastic nonwoven fabric utilizing crimping of fibers, but elongation and elastic recovery are insufficient. In addition, polyamide, polyolefin,
Although there is a polyester elastomer, sufficient extensibility cannot be obtained. Above all, a nonwoven fabric made of polyurethane is good in terms of elasticity (Japanese Patent Laid-Open No. 59-223347 and others). However, when used for a poultice base fabric or the like, there are drawbacks such as poor coarseness and difficulty in applying a poultice, and unsuitable for this use due to a somewhat high modulus, poor weather resistance, and yellowing. On the other hand, the present inventors have disclosed in Japanese Patent Application No. Hei.
No. 4 proposed an elastic nonwoven fabric comprising a block copolymer used in the present invention. With this proposal, the elasticity and elastic recovery were sufficient, the weather resistance was also improved, and the occurrence of discoloration such as yellowing was eliminated.

[0003] However, as a result of subsequent studies, the nonwoven fabric according to this proposal is wound up on a roll and left for a long period of time. Due to the tackiness of the block copolymer, sticking occurs between the nonwoven fabrics and the roll is unwound and used. The disadvantage of unsuccessfully unwinding was apparent.

On the other hand, the present inventors have disclosed in Japanese Patent Application No. Hei.
No. 8272 proposes to eliminate the sticking between the nonwoven fabrics by blending 5 to 30% by weight of a polyolefin with respect to the block copolymer.

[0005] Although the problem of sticking was almost solved by this, in a subsequent study, when the blending ratio of the polyolefin was 15% by weight or less, the nonwoven fabric wound in a roll was unwound at a speed of 20 m / min or more per minute. In this case, it was found that poor unwinding occurs due to slight sticking between the nonwoven fabrics.

[0006]

SUMMARY OF THE INVENTION The present invention provides an excellent stretchable nonwoven fabric comprising a block copolymer as proposed above, which is excellent in stretchability and elastic recovery, has good weather resistance, and has no discoloration such as yellowing. An object of the present invention is to completely prevent the nonwoven fabric from sticking and to stably unwind even at high speed without impairing the features.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have found that they can be solved by the following constitution, and have reached the present invention.

That is, according to the present invention, (1) the polymer block A mainly composed of an aromatic vinyl compound is contained in an amount of 10 to 50% by weight and the following formulas [1] and [2] (wherein [2] is 0%). ~ 2
9 to 83% by weight of a block copolymer composed of 90 to 50% by weight of a polymer block B mainly composed of a repeating unit represented by the following formula: Long chain fatty acid 1 of number 16 to 36
At least one fatty acid compound selected from the group consisting of fatty acid amides in which three or more are bonded to ammonia or an amine having 5 or less carbon atoms, fatty acid esters bonded to alcohols having 5 or less carbon atoms, and calcium salts of the fatty acids; Highly stretchable non-woven fabric consisting of fibers of a mixed polymer with 2.0% by weight.
And

(2) 10 to 50% by weight of a polymer block A mainly composed of an aromatic vinyl compound is represented by the following formulas [1] and [2] (wherein the formula [2] is 0 to 20 mol%). The polymer block B mainly composed of the repeating unit represented by
94.5 to 50% by weight of a block copolymer
83% by weight, 5 to 15% by weight of a crystalline polyolefin and 1 to 3 long-chain fatty acids having 16 to 36 carbon atoms combined with ammonia or an amine having 5 or less carbon atoms, combined with an alcohol having 5 or less carbon atoms A method for producing a highly stretchable nonwoven fabric, comprising mixing and melting and melt-blowing at least 0.5 to 2.0% by weight of at least one fatty acid compound selected from the group consisting of a fatty acid ester and a calcium salt of the fatty acid.

[0010]

Embedded image

(However, in the formulas [1] and [2], any one or two of R _{1 to} R ₄ are a methyl group, and the rest are hydrogen atoms.)

The block copolymer in the present invention is obtained by hydrogenating a block copolymer consisting of a polymer block A mainly composed of an aromatic vinyl compound and a polymer block B 'mainly composed of a conjugated diene compound. By hydrogenating at least 80% of the aliphatic double bonds based on

As the aromatic vinyl compound referred to in the present invention, styrene is most preferred in view of cost. Examples of the conjugated diene include 1,3-butadiene, isoprene, pentadiene, and hexadiene, and isoprene is suitable for the purpose of the present invention.

The styrene content of the hydrogenated block copolymer used in the present invention is in the range of 10 to 50% by weight. If the styrene content is 10% or less, moldability and heat resistance are poor. If the styrene content is 50% by weight or more, the stretchability and flexibility are reduced, and the object of the present invention cannot be achieved.

The hydrogenated block copolymer used in the present invention must have been hydrogenated to 80% or more, preferably 90% or more, of the isoprene double bond based on the conjugated double bond. Below this, there is a problem that thermal deterioration is apt to occur during melt molding, and the weather resistance of the obtained nonwoven fabric is also poor.

Next, important points in the present invention are a hydrogenated block copolymer (hereinafter abbreviated as SEPS), a crystalline polyolefin and a long-chain fatty acid having 16 to 36 carbon atoms.
At least one fatty acid compound selected from the group consisting of a fatty acid amide in which up to three are bonded to ammonia or an amine having 5 or less carbon atoms, a fatty acid ester bonded to an alcohol having 5 or less carbon atoms, and a calcium salt of the fatty acid (hereinafter simply referred to as fatty acid (Abbreviated as compound) with SEPS 94.5 to
83% by weight, 5 to 15% by weight of a crystalline polyolefin, and 0.5 to 2.0% by weight of a fatty acid compound.

That is, the ratio of SEPS is greater than 94.5% by weight, that is, the sum of the ratio of the crystalline polyolefin and the fatty acid compound is less than 5.5% by weight (however, 0.5 to 2. 0% by weight)
When the obtained nonwoven fabric is wound into a roll and left to stand, S
Due to the tackiness of the EPS, strong sticking occurs between the nonwoven fabrics, and the unwoven fabric cannot be unwound from the roll. This stickiness is caused by the fact that SEPS is amorphous and the glass transition point of the block copolymer B portion is lower than room temperature.
It is thought that the crystalline polyolefin is finely dispersed uniformly in the obtained mixed fiber with good dispersibility at the time of melt mixing with SEPS, but the compatibility is not so good that the polyolefin is exposed to the fiber surface and thus appears. It is considered that the effect of preventing the above-mentioned sticking was not exhibited due to insufficient blending of the crystalline polyolefin.

Further, it is considered that the effect of preventing the above-mentioned sticking, which is expected due to the lubricating effect and the releasing effect of the fatty acid compound, was not sufficiently exhibited due to the shortage of the compounding amount.

On the other hand, the ratio of SEPS is 83% by weight.
When the sum of the ratios of the crystalline polyolefin and the fatty acid compound exceeds 17% by weight (however, the ratio of the fatty acid compound is 0.5 to 2.0% by weight), the occurrence of sticking between the nonwoven fabrics is caused. However, the effect of the properties of the crystalline polyolefin becomes so large that the modulus of the obtained nonwoven fabric rapidly increases and the elasticity is greatly reduced, and the characteristics of the nonwoven fabric of the present invention are lost. Would.

Therefore, the mixing ratio of SEPS and the mixture of crystalline polyolefin and fatty acid compound is SEPS 9
It must be 4.5 to 83% by weight, a mixture of crystalline polyolefin and fatty acid compound 5.5 to 17% by weight (the ratio of the fatty acid compound is 0.5 to 2.0% by weight).

Next, as an important point in the present invention, SEP
As a compound to be added in addition to S and the crystalline polyolefin, 1 to 3 long-chain fatty acids having 16 to 36 carbon atoms were bonded to ammonia or a fatty acid amide bonded to an amine having 5 or less carbon atoms, or to an alcohol having 5 or less carbon atoms. It is to use at least one fatty acid compound selected from the group consisting of a fatty acid ester and a calcium salt of the fatty acid.

This fatty acid compound is generally known as a lubricant for synthetic resins. Here, when the fatty acid has less than 16 carbon atoms, the compound has a low molecular weight, and thus SEP
The compatibility with S and the crystalline polyolefin becomes too good, and the effect of preventing sticking of the SEPS high elastic nonwoven fabric, which is the object of the present invention, is not exhibited. On the other hand, if the number of carbon atoms exceeds 36 or the number of bonded fatty acids exceeds 3, the molecular weight increases and the compatibility with SEPS or crystalline polyolefin deteriorates, and the dispersion in them increases. Bleed-out occurs severely during the melt blown process, and the process condition of the melt blown process is significantly reduced due to nozzle contamination, fuming, and the like. With 16 or more carbon atoms
36, when the number of fatty acids is 1-3, the lubricant is SEPS
Shows moderate compatibility and dispersibility, and bleed-out in the melt blown is extremely small, and the process condition is not impaired.

As described above, although the exact mechanism by which the fatty acid compound prevents the sticking of the SEPS highly stretchable nonwoven fabric after winding in the present invention is not known, the fatty acid compound originally has a lubricating effect, a releasing effect and a crystal. Since the anti-sticking action of the reactive polyolefin is exerted additively, S
It is estimated that prevention of sticking during winding of the SEPS high elastic nonwoven fabric due to the rubber-like properties of EPS is realized.

An important point in the present invention is that the amount of the fatty acid compound to be added to the whole of SEPS and the crystalline polyolefin is 0.1%.
5 to 2.0% by weight. That is, when the content is less than 0.5% by weight, the above-described effect of preventing sticking is significantly reduced. On the other hand, when the amount exceeds 2% by weight, bleed-out occurs at the time of melt blown, thereby lowering the process condition and deteriorating the performance of the obtained nonwoven fabric, particularly, the light resistance. Therefore, the amount of the fatty acid compound is 0.5 to 2.0.
% By weight, and preferably 0.7 to 1.0% by weight.

The fatty acid compound satisfying the present invention has 1 carbon atom.
1 to 3 long-chain fatty acids of 6 to 36 are selected from the group consisting of fatty acid amides bonded to ammonia or amines having 5 or less carbon atoms, fatty acid esters bonded to alcohols having 5 or less carbon atoms, and calcium salts of the fatty acids. It is at least one fatty acid compound, for example, stearic acid amide, calcium stearate and the like. Particularly preferred is ethylene bisamide stearate.
Since it has a relatively long molecular chain length of 38 carbon atoms, it exhibits an extremely good anti-sticking effect and has high thermal stability, so that it cannot be melted at a relatively high temperature like a melt blown product. A stable process condition is maintained in the process.

In the present invention, as the polyolefin to be mixed with SEPS, polyethylene, polybutylene, or the like can be used. However, polypropylene is most effective in preventing sticking, and it is preferable to use polypropylene. Although the reason why polypropylene is excellent is not exactly known, the dispersibility at the time of melt mixing with SEPS is fine and evenly finely dispersed in the obtained mixed fiber, but the compatibility is not so good. It is presumed that it is likely to be exposed.

The SEPS used in the present invention is obtained by anionic polymerization in a hydrocarbon solvent using an organolithium compound or sodium metal as an initiator. The hydrogenation reaction can be performed using a noble metal such as platinum or palladium, an organic nickel compound, an organic cobalt compound, or a composite catalyst of these compounds and another organic metal compound.
The hydrogenation rate can be calculated by an iodine value measurement method.

The thermoplastic elastomer used in the present invention contains the above-mentioned SEPS as an essential component. If necessary, a hydrogenated product such as a paraffinic oil may be added to improve the flow processability. You can also.
In addition, various additives can be added in order to further improve the functions of the polymer such as heat resistance, weather resistance, and flame retardancy.

In the present invention, SEPS of a fatty acid compound is used.
The same method as that suitable for production of a general composition is used as a compounding method. For example, after once mixing SEPS and fatty acid compound with a Hensyl mixer, ribbon blender, etc.,
Melt kneading by an extruder, melt kneading of SEPS and fatty acid compound directly in a twin screw extruder, SE
A method of adding a fatty acid compound during melt polymerization of PS is used.

The highly stretchable nonwoven fabric of the present invention is prepared by directly forming a thermoplastic resin by melt spinning a thermoplastic resin using SEPS mixed with a fatty acid compound as a raw material, that is, by using a high-speed gas. After that, it can be manufactured by a method of manufacturing a nonwoven fabric by collecting in a sheet shape. That is, JP-A-49-10258, JP-A-49-48921, and JP-A-50-12.
In the various methods proposed in, for example, Japanese Patent No. 1570, etc., the raw material polymer is supplied to the extruder only by changing it so that the SEPS and the crystalline polyolefin are pelletized and weighed to a predetermined ratio and then mixed. You can do it.

In these melt blown methods, the raw material polymer is converted into a fiber and a non-woven fabric in one step.
It is suitable for forming a nonwoven fabric of an adhesive and sticky polymer, but the present invention is also typically applicable thereto.

The mixed polymer used in the present invention has excellent processability such as heat resistance and fluidity, and can be molded with the same ease as ordinary thermoplastic polymers such as polypropylene. It is possible to obtain an arbitrary nonwoven fabric by variously changing the amount of the jet fluid.

[0033]

EXAMPLES Examples of the present invention will be shown below to explain the present invention more specifically, but the content of the present invention is not limited to these examples. In this example, the physical properties of the nonwoven fabric were measured according to JIS L-1092.

Examples 1 to 8 and Comparative Examples 1 to 12 Cyclohexane 3,000 was placed in a pressure vessel equipped with a stirrer.
Parts by weight, 55 parts by weight of sufficiently dehydrated styrene and 0.7 parts by weight of n-butyllithium were added, polymerization was carried out at 60 ° C. for 60 minutes, then 300 parts by weight of isoprene was added, followed by 60 minutes, and then 55 parts by weight of styrene were added. And polymerized for 60 minutes to synthesize a styrene-isoprene-styrene type block copolymer. The styrene content of the obtained polymer is 2
7% by weight.

The polymer concentration of this polymer solution is 10%
Then, cyclohexane was added, degassed under reduced pressure, and then replaced with hydrogen. Further, a palladium catalyst of 0.5% by weight / polymer was added, and a hydrogenation reaction was performed under a hydrogen atmosphere of 10 kg / cm ² .
A hydrogenated block copolymer having a hydrogenation rate of 98% was obtained. Various amounts of ethylene bisamide stearate are blended with the block copolymer, melt kneaded and extruded to form SEPS.
Pellets were made.

Next, the SEPS pellets and MFR (measured at a melt flow rate of 230 ° C. under a load of 2160 g)
Weighed 200 homopolypropylene pellets,
The mixture was mixed at a predetermined ratio to obtain a mixed pellet.

After the mixed pellets were melted by an extruder, the pellets were mixed.
Orifices having a diameter of 3 mm were arranged at a pitch of 1 mm, and were fed into a melt blown spinning apparatus having slits for injecting heated gas on both sides to perform melt blown under the following conditions. That is, the temperature of the melt blown apparatus is set to 290 ° C., a polymer mixed at a predetermined ratio of 0.2 g / min per hole is discharged, and air heated to 285 ° C. is jetted 43 times the weight of the polymer to fibrillate. did. 20cm below the nozzle
Is collected on a wire mesh belt conveyor installed at the position of the above to form a nonwoven fabric having a basis weight of 70 g / m ² , and a diameter of about 50
It was wound into a roll of cm.

Table 1 shows a comparison between the mixing ratio of SEPS, polypropylene and bisamide stearate, and the evaluation results of the physical properties of the nonwoven fabric and the unwinding property of the rolled nonwoven fabric.

The method for evaluating the unwinding property of a roll-wound nonwoven fabric is as follows.
Set the rolled non-woven fabric on a freely rotating shaft,
It was evaluated as the stability of peeling between the nonwoven fabric and the nonwoven fabric when taken up at a speed of m / min, that is, the stability of unwinding. Table 1
In the evaluation of "good", the whole was unwound without any problem at all. "Poor" means that the unwoven fabric could not be unwound due to unstable peeling due to sticking between the nonwoven fabrics.

[0040]

[Table 1]

As is clear from the results, in Examples 1 to 8 corresponding to the present invention, unwinding was successfully performed, and the nonwoven fabric had an elongation of 500% or more and a stress at 30% elongation of 3 g / cm / cm. g / m ² or less, it has both high elasticity and low modulus.

On the other hand, Comparative Example 1, which is out of the present invention,
In Nos. 2, 4, 5, 7, and 8, the unwinding property of the roll-wound nonwoven fabric is poor. Further, Comparative Examples 3 and 6, which are outside the present invention,
In Nos. 9 and 12, nozzle fouling during the melt blown was so severe that sampling of the nonwoven fabric was impossible. On the other hand, in Comparative Examples 10 and 11 outside the present invention, the unwound properties of the roll-wound nonwoven fabric were good, but the elongation of the nonwoven fabric was less than 500%, and the stress at 30% elongation was 2 g / cm / g / m. ² , and the high elasticity and low modulus of the present invention have not been realized.

According to the present invention, the nonwoven fabric obtained by the present invention has a good unwinding property from roll winding, so that it has excellent handleability when processed into various products, and has high elasticity and high elasticity without vulcanization. In addition, since it is a low modulus, it can exhibit its characteristics to a compress base cloth. In addition, it has excellent weather resistance compared to urethane elastic fibers and the like, so that discoloration and discoloration during use and yellowing hardly occur, so that it can be used for all uses except for high temperature use. Also, it has excellent low temperature characteristics.

Claims (2)

(57) [Claims] 1. A polymer block A mainly composed of an aromatic vinyl compound comprising 10 to 50% by weight of the following formula [1] and formula [2]:
When the polymer block B mainly composed of the repeating unit represented by the formula (where the formula [2] is in the range of 0 to 20 mol%) is 90 to 5
94.5 to 83% by weight of a block copolymer consisting of 0% by weight, 5 to 15% by weight of a crystalline polyolefin and 1 to 3 long-chain fatty acids having 16 to 36 carbon atoms containing ammonia or an amine having 5 or less carbon atoms Fatty acid amide bonded with 5 carbon atoms
A highly stretchable nonwoven fabric comprising a mixed polymer fiber containing 0.5 to 2.0% by weight of at least one fatty acid compound selected from the group consisting of a fatty acid ester bonded to an alcohol and a calcium salt of the fatty acid. Embedded image (However, in formulas [1] and [2], any _one of R _{1 to} R ₄
Two are methyl groups and the rest are hydrogen atoms. ) 2. A polymer block A containing an aromatic vinyl compound as a main component in an amount of 10 to 50% by weight, represented by the following formulas (1) and (2).
When the polymer block B mainly composed of the repeating unit represented by the formula (where the formula [2] is in the range of 0 to 20 mol%) is 90 to 5
94.5 to 83% by weight of a block copolymer consisting of 0% by weight, 5 to 15% by weight of a crystalline polyolefin and 1 to 3 long-chain fatty acids having 16 to 36 carbon atoms containing ammonia or an amine having 5 or less carbon atoms Fatty acid amide bonded with 5 carbon atoms
A highly stretchable nonwoven fabric characterized in that 0.5 to 2.0% by weight of at least one fatty acid compound selected from the group consisting of a fatty acid ester combined with the following alcohol and a calcium salt of the fatty acid is melt-blown and melt-blown. Manufacturing method. Embedded image (However, in formulas [1] and [2], any _one of R _{1 to} R ₄
Two are methyl groups and the rest are hydrogen atoms. )