JPS6155249A - Production of antistatic polyurethane elastic nonwoven fabric - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing an antistatic polyurethane elastic fiber nonwoven fabric.

Conventional Technology A wide variety of nonwoven fabrics have been proposed and used in many fields, but most of these nonwoven fabrics are composed of inelastic polymers such as polyamide, polyester, and polyolefin. Antistatic nonwoven fabrics made of highly elastic fibers such as neutral polyurethane have not been put to practical use. Regarding nonwoven fabrics made of polyurethane elastic fibers, several proposals have been made for Gζ. For example, Japanese Patent Publication No. 4B-26578 describes short f! of polyurethane elastic fibers! It has been proposed to treat fine webs with aldehydes. or.

Japanese Patent Publication No. 48-26592 proposes subjecting a web made of short fibers of polyurethane elastic fibers to heat and pressure treatment. Furthermore, Japanese Patent Publication No. 52-81177 proposes a method in which a polyurethane intellectual substance is dry-spun to form a web containing a solvent, and then the solvent is removed. However, in either method, the resulting nonwoven fabric tends to have weak bonds between fibers or to be coarse and rigid, making it impossible to obtain a high-quality product. Furthermore, the manufacturing process becomes complicated, which is extremely disadvantageous in terms of economics. Furthermore, antistatic f!
No effort has been made to give E.

At present, there is no known method for industrially advantageous production of antistatic polyurethane elastic fiber nonwoven fabrics.

Problems to be Solved by the Invention The inventors of the present invention have developed an antistatic polyurethane elastic fiber non-woven fabric. We have carried out intensive research and examination on +4 construction and have completed 71 inventions.

That is, the object of the present invention is to improve the antistatic property l? An object of the present invention is to provide a polyurethane elastic fiber nonwoven fabric. Another object is to provide an industrially advantageous method for manufacturing such nonwoven fabrics.

Means for Solving the Problems In the method of the present invention, after adding and kneading a polyisocyanate compound to a molten polyurethane elastic body, when manufacturing a nonwoven fabric by a melt blowing method, conductive fibers are entrained in a high-speed air stream and mixed together with the polyurethane elastic fibers. Deposit and collect the dielectric fibers in a sheet form, and add 0.05 to 5 layers of the dielectric fibers! It is characterized by containing 1%.

As the polyurethane elastomer applied to the present invention, known segmented polyurethanes can be used, but melt-spuntable thermoplastic polyurethane elastomers are particularly suitable. Such a polyurethane elastomer is made of a low melting point polyol with a molecular weight of 6,000 to 6000, such as dihydroxy polyether, dihydroxy polyester, dihydroxy polycarbonate, dihydroxy polyester amide, etc. and an organic diisocyanate with a molecular weight of 500 or less, such as P, P'
- diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, 2,6-diycyanatomethyl caproate, hexamethylene diisocyanate, etc. and a chain extender with a molecular weight of 500 or less, such as glycol, amino It is a polymer obtained by reaction with alcohol or triol.

Among these polymers, a particularly good one is polytetramethylene glycol as the polyol.

Or polyurethane using polyε-caprolactone or polybutylene adipate. When polyethylene glycol is used as a polyol, it improves ice-making properties and is therefore used for special purposes.

Moreover, p,p-diphenylmethane diisocyanate is suitable as the organic diisocyanate.

Moreover, pop'-bishydroxyethoxybenzene and 1,4-butanediol are suitable as chain extenders.

The polyisocyanate compound used in the present invention.

Compounds having at least two isocyanate groups with an average molecular weight of 400 or more are preferred, such as molecules J1500 to 600 used in the synthesis of polyurethane elastomers.
It can be synthesized by reacting 0 polyol with twice the molar amount of an organic diisocyanate having a molecular weight of 500 or less.

At this time, a compound having eight or more hydroxyl groups may be used as the polyol. Also used are organic diisocyanate dimers. Suitable polyisocyanate compounds include polytetramethylene glycol, polycaprolactone, and polybutylene adipate having hydroxyl groups at both ends of the molecule ff 1500 to 2000, or a compound obtained by adding p,p'-diphenylmethane diisocyanate to polybutylene adipate in two moles. I can do it.

The amount of the polyisocyanate compound added is preferably 5 to 30 M%, particularly preferably 10 to 20% by weight. The amount added varies depending on the type of polyisocyanate compound used, but if the amount added is small, the intended physical performance of the polyurethane nonwoven fabric will be insufficient and the effect of improving spinning operability will be small. Moreover, if the amount added is too large, non-uniform mixing, deterioration of yarn quality, etc. tend to occur, and the spinning operation becomes unstable, which is not preferable.

The molecular weight of the polyisocyanate compound used in the present invention is usually 400 or more, preferably 800 to 3000.9 The molecular weight of the polyisocyanate compound used in the present invention is the apparent molecular weight calculated from the isocyanate group weight measured by amine titration method. be.

The conductive fiber used in the present invention has an electric resistance C of a single yarn per length 1α (measured by applying about 100 V/crn DC) of 1O'. It is preferably Ω/cm or less. Such conductive fibers include thin metal wires (e.g., silver, copper, aluminum, stainless steel, etc.), organic fibers plated with metals or conductive metal compounds (e.g., indium oxide, etc.), and organic fibers coated on the surface or inside of organic fibers. A conductive layer of a conductive metal compound (e.g. copper iodide, copper sulfide, indium oxide, etc.) formed by chemical means, an organic fiber having a conductive resin film containing conductive particles such as carbon black,
Examples include a composite of a conductive polymer (conductive layer) containing conductive particles such as carbon black and a non-conductive polymer during spinning. Conductive particles other than carbon black include metal particles, metal compound (semiconductor) particles such as zinc oxide, tin oxide, and copper sulfide, and inorganic particles such as titanium oxide particles that contain zinc oxide, tin oxide, and indium oxide on the surface. Examples include conductive metal oxides such as, and those formed with metal films.

All kinds of conductive fibers can be used for the purpose of the present invention, but fine metal wires are more difficult to handle than organic fibers, and fibers with a conductive film on their surface tend to peel off the film due to friction. Therefore, conductive composite fibers in which a conductive component and a non-conductive component are combined during spinning are most preferable.

The conductive fiber is preferably contained in an amount of 0.05% to 5% by weight of the total M amount of the nonwoven fabric, more preferably 0.1% to 3% by weight.
It is. The content varies depending on the type of conductive fiber used, but if the content is small, it will be difficult to obtain the desired antistatic performance.

In addition, if the content is too high, the antistatic performance will improve, but the greatest feature of polyurethane elastic fiber nonwoven fabric
It is not preferable because flexibility and elasticity are impaired.

The meaning of adding and kneading a polyisocyanate compound to the polyurethane elastomer of the present invention is that the added and kneaded polyisocyanate compound reacts to form crosslinks after fiber formation. It has different properties from the body, and is insoluble in dimethylformamide, tetrahydrofuran, etc. at room temperature.

For this reason, the nonwoven fabric of the present invention has high strength (and has excellent stretch recovery properties), and exhibits performance that has not been obtained in the past.The polyisocyanate compound used in the method of the present invention improves the physical properties of the resulting nonwoven fabric. In addition, it has the effect of lowering the melt viscosity of the polyurethane elastomer during the spinning process, making it possible to lower the spinning temperature, making it easier to avoid thermal decomposition of the polyurethane elastomer. , the spinning operability is improved.Also, since the polyurethane elastic fibers deposited as a nonwoven fabric have a high adhesiveness, the bond with the conductive fibers is also strong, making it unnecessary to use adhesives (by pressing, etc.). Nonwoven fabrics can be easily obtained.

The production of the nonwoven fabric of the present invention involves a part for melt-extruding the thermoplastic polyurethane elastomer, a part for adding and mixing the polyisocyanate compound, a spinning device equipped with a spinning head for the nonwoven fabric, and a part for supplying the conductive fibers with high-speed airflow. Preferably, it is carried out by a device.

As such a spinning device, a known device used for adding a modifier during spinning can be used. In addition, as a spinning head for nonwoven fabrics, any known shape can be used, and in particular, a spinning head equipped with a nozzle for discharging molten polyurethane and slits on both sides of the nozzle for discharging heated inert gas is suitable. Such a spinning head is described, for example, in Japanese Patent Publication No. 41-788:15.

Although it is possible to use a mixing device having a rotating part in the part where the polyisocyanate compound is added to and mixed with the molten polyurethane, it is more preferable to use a mixing device having a static mixing element. . As the kneading device having a static kneading element, a known one can be used.

The shape and number of elements of the static kneading rope vary depending on the conditions of use, but are selected so that the polyurethane elastic body and polyisocyanate compound are sufficiently mixed before being discharged from the spinneret. It is essential to do so.

Further, as a device for supplying the conductive fibers, a known air sucker can be used, but a device that can control the supply amount (and has a yarn speed control) is preferable.

The installation method or number of air soccer is conductive T!
i. It varies depending on the dispersion state or content of the IM fibers on the surface of the polyurethane elastic fiber nonwoven fabric.

For example, use one air soccer to make your head shake from side to side.

Methods include a method of incorporating it in a V-shape on the surface of a nonwoven fabric, a method of incorporating it in a straight line with several fixed air suckers, or a method of incorporating it over the entire surface by swinging several air suckers. , the number can be used,
It is important to select appropriately depending on the intended use of the product.

Mata, regarding the place to install the air soccer, for example, how to install the air soccer so that the polyurethane elastic fibers are sprayed and deposited on the net on the same line, and the air soccer is deposited at the same time, or the polyurethane elastic!
/3 The fiber nonwoven fabric can be attached in any location before it is wound up as a product, but the bond between the polyurethane elastic fiber and the conductive mineral fiber tends to be strong. It is more preferred to install the air soccer so that the fibers are deposited on the net at the same time.

An example of an embodiment of the present invention will be described below.

A pellet of thermoplastic polyurethane elastomer is fed from a hopper and heated and melted in an extrusion manner. Melting temperature is 190-2
A range of 30°C is preferred. Ten thousand.

Polyisocyanate compound in the supply tank.

It is melted at a temperature of 100°C or less and degassed in advance.

If the melting temperature is too high, it tends to cause deterioration of the polyisocyanate compound, so it is preferably as low as possible within the melting range, and a temperature between room temperature and 100'C is appropriately used. The molten polyisocyanate compound is metered using a metering pump, filtered if necessary, and added to the molten polyurethane at a meeting point provided at the tip of the extruder. The polyisocyanate compound and polyurethane are C-kneaded using a mixer having a static kneading element. This mixture is metered by a meter pump and introduced into the spinning head.

The spinning head uses an ordinary device for spinning nonwoven fabrics (although it is preferable to design the shape so that the mixture has as few pores as possible. If necessary, a base layer provided in the spinning head may be made of wire mesh or glass). After removing foreign matter with a filter medium such as peas, the mixture is discharged from the nozzles arranged in a row, ejected from the slit, heated and atomized by the fast air current, and deposited and collected on the moving net. be done.

- The conductive fibers pass through a nip roller whose speed is set so as to have a predetermined content, are sucked and ejected by an air sucker, and are deposited on the net at the same time as the polyurethane elastic AIM. The web collected by the net is immediately pressed with a roller, if necessary, and taken off as a nonwoven fabric. As described above, the method of the present invention makes it possible to industrially advantageously produce an antistatic polyurethane elastic fiber nonwoven fabric.

Effects of the invention Furthermore, the nonwoven fabric obtained by the method of the invention has a cutting elongation of 8
It has a recovery rate of 85% or more when elongated at 100% or more, and is used alone for 6-resistance purposes due to its excellent elasticity, flexibility, breathability, and antistatic properties, but it is used for other materials as well. By combining it with other products, it is possible to create even more diverse products. Such materials include inelastic polymers, such as synthetic fibers such as polyester, nylon, polyolefin, and acrylic, or knitted fabrics made of natural pancreatic fibers such as cellulose and wool;
Examples include net fabric, nonwoven fabric, and web. Further, films such as polyurethane, foam sheets, etc. may also be used.

Such products are used as materials for various clothing such as sportswear and foundations that require elasticity, as well as interlining, filling, and reinforcing agents.

There are stretch tapes, bands, etc. In addition, it is useful as packing materials, cushioning materials, fillers, and molding materials because of its ability to fit into various shapes, cushioning properties, and moldability. Furthermore, applications that take advantage of the friction coefficient and wear resistance unique to polyurethane elastic materials include various anti-slip applications such as shoe lining materials.

Furthermore, this nonwoven fabric is extremely useful in fields where antistatic performance is required, as it exhibits particularly excellent effects.

The present invention will be explained in the following examples.

Example: 5,550 parts of dehydrated polytetramethylene glycol with a hydroxyl value of 102 (all parts below refer to parts by weight) and 50 parts of 1,4-bis(β-hydroxyethoxy)benzene.
0 parts and 1960 parts of P,P'-diphenylmethane diisocyanate were combined in a Niguu and heated to 85°C to obtain a powdered polyurethane. This was molded into pellets using an extruder.

Concentrated IJjl F/1 in dimethylformamide at 25°C
The relative viscosity of 00aa is 2. It was an office worker.

On the other hand, 1000 parts of polytetramethylene glycol having a hydroxyl value of 112 and 500 parts of P,P-diphenylmethane diisocyanate were reacted at 80°C for 80 minutes to obtain a viscous polyisocyanate compound.

The incyanate group content of this product was 5.60%.

10,000, nylon 6 containing 35% carbon black (!i) is arranged in the center, and nylon 6 containing 2% titanium oxide is sandwiched on both sides by melt composite spinning (volume composite ratio 1
/l O), a 9 denier/8 filament was obtained from an 8-layer conductive composite fiber with a circular cross section obtained by stretching and crimping (see Figure 1 of JP-A-54-80919). The electrical resistance of this material per 13 was 7.8×10 7 Ωm.

Using the polyurethane elastomer pellets and polyisocyanate compound thus obtained as raw materials, an extruder equipped with a mixing section consisting of a polyisocyanate compound supplying device of 1 g and a stationary kneading element, and a 0,5φ150 extruder arranged in a - row.
A melt blow spinning device having slits for ejecting heated gas on both sides of the hole nozzle is used, and 0.00 mm per nozzle is used. Bf
Polymer was discharged at a rate of /wa, and air heated to 220"C was heated at a pressure of 4.5kq/cIIN to 2000
NJ? /mix was injected from the slit to make it thin. - The conductive fibers were also passed through a nip roller set at a predetermined speed, sucked into the air sucker into which the heated air had been introduced, and jetted out while shaking the head from side to side. The fine polyurethane elastic fibers and the conductive fibers ejected from the air sucker were collected simultaneously on a conveyor made of a 5G mesh wire mesh placed 25 tYn below the nozzle, and then pulled between rollers to obtain a nonwoven fabric.

The date of the nonwoven fabric is 809/rrl, and the amount of polyisocyanate compound added is varied, the content of conductive fiber is varied, and the content of conductive fiber is varied. The characteristics were as shown in Table 1. When a polyisocyanate compound is not added, it is necessary to raise the spinning temperature, and the resulting product also has low strength and elongation, and has a poor 100% elongation recovery rate. Incidentally, thread breakage occurred when the amount added was 35%.

Moreover, the antistatic performance effect begins to appear when the content of conductive fiber is 0.05%. However, when the content was 7%, although the antistatic effect was very good, the flexibility and stretchability, which are the most important features of polyurethane elastic fiber nonwoven fabrics, were lost, and the product value was low.

In addition, the frictional charging voltage is calculated by rubbing against wool cloth 10 times (20℃,
'40%RH) Measured value after 1 second.

Claims (4)

[Claims] (1) After adding and kneading a polyisocyanate compound to a molten polyurethane elastic body, when manufacturing a nonwoven fabric by a melt blowing method, conductive fibers are entrained in a high-speed air stream, deposited and collected in a sheet form together with the polyurethane elastic fibers, A method for producing an antistatic polyurethane elastic fiber nonwoven fabric, characterized in that the conductive fiber is contained in an amount of 0.05 to 5% by weight. (2) The method according to claim 1, wherein 0.1 to 3% by weight of the total weight of the nonwoven fabric is comprised of conductive fibers. (3) The method according to claim 1, wherein the conductive fiber is a metal fiber or a fiber having a conductive layer containing conductive particles selected from metals, metal compounds, and carbon black. (4) The conductive fiber is a composite fiber in which a fiber-forming polymer is bonded to a conductive layer containing metal particles, conductive metal compound particles, or conductive carbon black particles. Method.