JPH02112456A - Nonwoven fabric made of polypropylene - Google Patents

Abstract

PURPOSE:To obtain the subject nonwoven fabric resistant to hardening of feeling, having excellent tensile strength and suitable for operating gown, etc., by using a polypropylene having an isotactic pentad fraction falling within a specific range. CONSTITUTION:The objective nonwoven fabric is produced by using a polypropylene having an isotactic pentad fraction (abbreviated as I5) of 0.880-0.930 and an I5 difference between a boiling cyclohexane insoluble fraction and a boiling cyclohexane soluble fraction of >=0.050. The polypropylene is preferably a polypropylene mixture produced by mixing two or more kinds of polypropylenes having different I5 values of the resins and different I5 values between the boiling cyclohexane insoluble fraction and soluble fraction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a nonwoven fabric made of polypropylene. The polypropylene nonwoven fabric of the present invention can be used for medical and sanitary materials such as surgical gowns, surface materials for disposable diapers and sanitary products, as well as for wastewater drainage, as well as nonwoven fabrics made from conventionally used polypropylene resin, nylon mK&, polyester resin, etc. It is widely used in fields such as civil engineering materials such as lumber and ground improvement materials, industrial materials such as house lining curtains, and industrial materials such as oil adsorbents.

(Nine Conventional Technologies) Generally, nonwoven fabrics are manufactured through the process of fibers → web (fiber aggregate in which fibrous thermoplastic resin is dispersed in sheet form) → bonding.

Fibers using thermoplastic resin are produced by drawing an undrawn spun product that is cooled and solidified after melt spinning. There are some that are made into fibers. After melt spinning, the thermoplastic resin fibers obtained by drawing the undrawn spun product that has been cooled and solidified become fibers with improved strength and elasticity. It is used as a raw material for nonwoven fabrics, either as staples or as long fibers.

Is the web forming method the initial process of spinning? There are two methods: one method is to make a web by spinning, and the other is to make a web by dispersing the fibrous thermoplastic resin injected from a spinning nozzle into sheets. The fibers formed into a web are then bonded together by applying a suitable compound or physical energy to the core.

Currently, most of the nonwoven fabrics manufactured from polypropylene fibers have convex portions that are obtained by reclamation of a web obtained from Q fibers obtained by stretching an undrawn spun product that has been melt-spun, cooled, and solidified. It is manufactured by thermocompression bonding between a heat roll (emboss roll) and a heat smooth roll (flat roll). Therefore, on the surface of the obtained polypropylene nonwoven fabric, recesses were formed by thermocompression bonding, and the recesses were scattered independently and at intervals. Such recesses formed by thermocompression bonding are indispensable for obtaining substantial physical properties of the nonwoven fabric, such as prevention of fluffing and prevention of interphase peeling.

However, such thermocompression-bonded parts have the disadvantage that excessive heat fusion causes the fibers to melt and form a film, making it brittle and hard, and causing hardening of the texture of the nonwoven fabric. In order to avoid such hardening of the texture of the nonwoven fabric, it is possible to lower the pressure bonding temperature between the embossing roll and the flat roll, but if the pressure bonding temperature is lowered, the heat fusion bond between the fibers will be insufficient in the thermocompression bonded area. However, it has the disadvantage that the tensile strength of the obtained nonwoven fabric is not improved and cannot be put to practical use. In order to keep the thermocompression bonding temperature low and to achieve practical bonding, for example, the sheath component resin has a lower melting point than the core component resin. Nonwoven fabrics made from fibers with a core-sheath structure have conventionally been manufactured. However, fibers having a core-sheath structure have disadvantages in that the manufacturing method thereof is complicated and the cost is high.

(Problems to be Solved by the Invention) In order to improve the above-mentioned hardening of the texture of a nonwoven fabric due to excessive heat fusion between fibers or the decrease in tensile strength of a nonwoven fabric due to insufficient heat fusion between fibers, Using the isotactic pentad fraction (hereinafter referred to as ■) of polypropylene as a stereoregularity parameter, we conducted intensive research on the performance of similar fiber nonwoven fabrics using polypropylenes with different stereoregularities. As a result, polypropylene with a value of 0.880 or more, 0.930, and a difference of 1 between the insoluble part in boiling cyclohexane and the soluble part in boiling cyclohexane of 0.050 or more was used as raw material. It was discovered that by using such fibers, it was possible to obtain a nonwoven fabric with improved tensile strength without causing texture hardening without changing the raw material fiber structure to the above-mentioned special structure.Based on this knowledge, the present invention was developed. completed.

As is clear from the above description, an object of the present invention is to provide a polypropylene nonwoven fabric that is free from hand hardening and has excellent tensile strength.

(Failure to solve the problem) The present invention has the following configuration.

(1) Isotactic pentad fraction is 0.88
0 or more and 0.930 or less, and the difference between the isotactic pentad fraction of the boiling cyclohexane insoluble part and the isotactic pentad fraction of the boiling cyclohexane soluble part is 0050 or more. Characteristic polypropylene non-woven fabric.

(2) A nonwoven fabric made of polypropylene, characterized in that the polypropylene described in item 1 above is a mixture of two or more types of polypropylene.

The polypropylene used for producing the nonwoven fabric of the present invention has an isotactic pentad fraction (mm) of 0.88.
0 or more and 0.930 or less, and the difference between I of the boiling cyclohexane insoluble part and I of the boiling cyclohexane soluble part is 0.050 or more.

If T exceeds 0.930, it will be difficult to spin undrawn yarn of 2.5 denier or less, and the thermocompression bonding temperature must be high during nonwoven fabric production, so it is necessary to This is undesirable because the resulting nonwoven fabric will harden due to the wearing temperature, making it impossible to obtain a nonwoven fabric with good texture.Furthermore, if a non-woven fabric with a groove of 0°880 is used, the tensile strength of the fibers themselves will increase. It is not preferable because the strength is low, and furthermore, it is difficult to control the thermocompression bonding temperature during the production of the nonwoven fabric, and as a result, it is easy to cause texture hardening due to the heat fusion temperature.

Also, 1. of the boiling cyclohexane insoluble part. When polypropylene is used, it is difficult to control the thermocompression bonding temperature during nonwoven fabric production, and the tensile strength of the resulting nonwoven fabric decreases due to insufficient thermal fusion. This is not preferable because it tends to cause texture hardening due to excessive heat fusion.

The polypropylene used in the present invention can be obtained, for example, by the following method. That is, a titanium-containing solid component (a solid compound mainly composed of titanium trichloride or a solid compound in which titanium tetrachloride is supported on a carrier such as magnesium chloride) is combined with an organoaluminium compound, and in some cases, an electron donor component is also added. Combined as the third component. It is obtained by polymerizing propylene in two or more stages using a so-called Ziegler-Natsuta catalyst, such as slurry polymerization in an inert solvent, bulk polymerization using propylene itself as a solvent, or gas phase polymerization using propylene gas as the main component. . The polymerization temperature during propylene polymerization was set at 40°C so that the temperature of the boiling cyclohexane soluble part was high.
At a relatively low temperature of ~80°C, the pressure is normal pressure ~50A:
9/iG, after polymerizing propylene for a polymerization time of 5 minutes to 20 hours,
So-called two-stage polymerization, in which propylene is polymerized at a relatively high polymerization temperature of 70°C to 90°C so that the Can be obtained legally.

However, the polypropylene used in the present invention is ■.

It is also possible to use a polypropylene mixture obtained by mixing two or more types of polypropylene in which the insoluble and soluble portions of boiling cyclohexane differ by 1°. At this time, the I of the mixture is 0.880 or more and 0.930 or less, and the boiling cyclohexane insoluble portion is 2.

The difference between the cyclohexane soluble part and the boiling cyclohexane soluble part is 0.05.
It is sufficient if it is 0 or more.

Two or more types of polypropylene may be mixed using a conventional mixing device such as a Hensel mixer (trade name), a Super Mixer ribbon blender, or a Pan Bali mixer.

In addition, the cyclohexane-insoluble part and the cyclohexane-soluble part in the present invention refer to the polypropylene that is completely dissolved in xylene mixed with a phenolic heat stabilizer, and then methanol is added to the xylene solution to completely precipitate the polypropylene. This is the cyclohexane-insoluble part and the cyclohexane-soluble part when polypropylene, which has been dried under vacuum at 80°C for 24 hours, is extracted with cyclohexane mixed with a phenolic heat stabilizer using a Soxhlet extractor for 8 hours. .

In the present invention, I refers to A.
Macromolecules (Mac
romolecules), 6.925 (1973)
This is the isotactic fraction in pentad units in a polypropylene molecular chain measured using the method published in 13C-NMR. Therefore, I is
This is the fraction of polypropylene monomer units in which five consecutive polypropylene monomer units are isotactic bonded. The peak attribution determination method in the above-mentioned NMR measurement is based on Macromolecules.
ules), 8.687 (1975).

For NMR in the examples described later, if the ratio is 5:1, 13C-NMR type GX270 manufactured by JEOL Ltd. is used, and 0.
~ Using DCB/C6D6 polypropylene 21 night,
The test was carried out at a temperature of 130° C. and a frequency of 678 MHz.

The nonwoven fabric of the present invention has ■: 0.880 or more and 0.930
Various antioxidants, neutralizers, and lubricants that are usually added to polypropylene for textiles are added to polypropylene or polypropylene mixtures in which the difference between the boiling cyclohexane insoluble part and the boiling cyclohexane soluble part is at least o, oso. After stirring and mixing for 3 to 5 minutes using a stirring mixing device such as Hensel Mixer (trade name) or Super Mixer, the mixture is heated to the melt crosstalk temperature using a single-screw or twin-screw extruder. The pellets are formed by melt-kneading and extrusion at 200°C to 300°C, and the resulting pellets are melt-spun and stretched using a known method for producing polypropylene fibers.
It can be obtained by fibrosing VJ, forming the ionized material into a web, and then forming it into a nonwoven fabric using a heat-sealing device that also includes an embossing roll and a flat roll.

(Example) Hereinafter, non-invention will be specifically explained based on Example 1 and Example 1], but the present invention is not limited thereto. In addition, the method for producing polypropylene and the evaluation method for the nonwoven fabric used in the examples and comparative examples of the present invention were as follows.

(1) Method for producing polypropylene Polypropylene with a value of 0.883 and I5 of 0.
The polypropylene No. 900 is a three-term titanium composition described in Japanese Patent Publication No. 59-28573, that is, titanium tetrachloride 0
．． 4 moles were heated to 35°C and added with 60 mol of n-hexane.
Milliliter, diethylaluminum monochloride 0
．． 05 mol, diisoamyl ether 0.12 mol 25
℃ for 1 minute, reacted at the same temperature for 5 minutes, added the entire amount of the reaction product solution dropwise over 30 minutes, and then heated to the same temperature for 3 minutes.
The temperature was raised to 75°C and reacted for an additional 11 hours, cooled to room temperature, the supernatant liquid was removed, 400 mIJ IJ liter of n-hexane was added, and the supernatant liquid was removed by decantation.Step 4 The entire amount of the obtained solid product (1) was dissolved in 300 ml of n-hexane. Add for about 1 minute at 6
After reacting for 1 hour at 5°C, 400 ml of n-
Presence of a catalyst consisting of a combination of a solid product obtained by adding hexane, stirring for 10 minutes, standing still, removing the supernatant liquid, and removing the supernatant liquid five times, and then drying the solid product under reduced pressure and diethylaluminum monochloride. Below, the polymerization pressure is 10 kF!
f/c7IG, the polymerization temperature of the first stage polymerization vessel was 70℃,
It was obtained by polymerizing propylene in two stages by adjusting the polymerization time under conditions where the second stage polymerization temperature was 85°C.

Also, ■, is 0.928, 0.887 and 0.872
The polypropylene was prepared by polymerizing at 70°C, 582°C and 85°C in the presence of a catalyst combining the titanium trichloride composition and diethylaluminium monochloride, and propylene was polymerized at 10 kgf/cdG under a pressure of 10 kgf/cdG. It was obtained by polymerization in stages.

(2) Polypropylene with a value of 0.919 is a hedral compound in which four-term titanium is supported on magnesium chloride, that is, 30 milliliters of decane, 4.8 grams of magnesium tetrachloride, 17 grams of orthotitanium an-butyl, and 2-
19.5 g of ethyl-1-hexanol was mixed and heated to 1300C for 1 hour with stirring to obtain a homogeneous solution.The homogeneous solution was heated to 7°C, and 1.8 g of diisobutyl phthalate was added for 1 hour. After lapse of time, silicon tetrachloride 52
gram over 2.5 hours to precipitate a solid, and then 700G.

Heat for 1 hour, then separate the solid (from the liquid and n-
The total amount of solid product (1) obtained by washing with hexane was 1.2
- mixed with 50 ml of titanium tetrachloride dissolved in 50 ml of dichloroethane, followed by the addition of 1.8 grams of diisobutyl phthalate and heated to 100° C. without stirring.
After reacting for 2 hours at the same temperature, the supernatant was removed by decantation, 50 ml of 1,2-dichloroethane and 50 ml of titanium tetrachloride were added again, stirred at 100°C for 2 hours, and diluted with hexane. Propylene was polymerized in one step at a polymerization temperature of 70° C. under a pressure cuff of 9 f/ciG in the presence of a PAW in which the washed facepiece product was combined with triethylaluminum and diphenylmethodisilane. I really got it.

(2) Evaluation method (1) Bending resistance The degree of hand hardening was evaluated by measuring bending resistance (based on CJISL 1018°6.21A).

The test piece for measuring bending resistance was 30 or more from the edges of both ends of the fabric made, and 50C7 from the end in the longitudinal direction. Length 50 mm, width 100 yn from the nonwoven fabric excluding L and above
Ten x test pieces were cut out and prepared.

Using the test piece, place the test piece on a horizontal table (cantilever type testing machine) with a smooth surface and a graduated scale having one side inclined at 45 degrees, aligned with the scale base line. Measurements were made by manually sliding the test piece gently in the direction of the slope, and when the center of one end of the nine pieces touched the slope, the position of the other end was read on the scale. For bending resistance, the length of the scale was expressed in millimeters (=), each average value was expressed as an integer, and the 7C value was taken as the measured value.

In other words, the higher the first measurement of bending resistance, the more the hand hardening progresses. The tactile sensation of bending resistance can be broadly classified as follows: If the bending resistance is 30 or less, it feels soft and soft, and if the bending resistance is over 30, it becomes hard and has a boa-boa feel.

((1) 2 50 prepared in the same manner as the test piece for measuring tensile strength and bending resistance.
Ten test pieces of ym and width of 100 ytrv were used, and the tensile strength was measured using a tensile tester at a tensile speed of 10 Q mm, 7 ml, and a sample gripping interval of 5α. The tensile strength shown in the examples below is the value obtained by converting the number of grams (hereinafter simply referred to as the basis weight) of one piece of nonwoven fabric as 209, that is, the tensile strength at break divided by the basis weight and the remainder of 20. Jita (I used direct. The fledgling was gram 15.
centimeter (g/5 cTL).

(iii) Tensile strength when bending resistance is 25 1 Read one stroke of the tensile strength when bending resistance is 25 = Y from the graph where the horizontal axis is tensile strength The tensile strength was measured at 25 degrees. The higher this value is, the better the performance as a nonwoven fabric is.

Example 1.2, Comparative Examples 1 to 4 As shown in Table 1 below, polypropylene having I5, a cyclohexane-insoluble part and a cyclohexane-soluble part of 15, calcium stearate O, 1 weight part, and Ciba Geigy as a stabilizer were added. IRGANOX
1425WL 0.05% by weight After stirring and mixing with a Schiffensel mixer (trade name) for 3 minutes,
Using a single-screw extruder, the mixture was melt-cross-extruded at 250'C and pelletized.

The obtained pellets were melted using a conventionally known parallel melt spinning machine having a screen nozzle made of 300 mesh wire mesh inside the nozzle and 450 nozzles with a nozzle hole diameter of 0.5 rtx%. spun.

The spinning process was performed at 300'C so that the undrawn yarn had a denier of 2.5 to 2.6 denier, and
i 110 g/mq, spinning yarn take-back XF: 880
It was performed at m/mjr. The obtained undrawn yarn was passed through an arc stretching roll K having a roll rotation ratio of 1.5 and a roll temperature of 50° C. to obtain a drawn yarn.

Furthermore, after winding the obtained drawn yarn and applying a thin K,
The web was cut to 0 mm and passed through a card machine at a winding speed of 7.5 m/min to obtain a web, and the web was heated to the temperature listed in Table 1 between an embossing roll and a flat roll at an embossing roll passing speed of 6 m/min. A nonwoven fabric made of polypropylene was obtained.

Using the obtained nonwoven fabric, a test piece for measuring bending resistance and a test piece for measuring tensile strength were prepared, and the bending resistance and tensile strength were measured. Further, the tensile strength value at a bending resistance of 25 was calculated.

The results are shown in Table 1.

Examples 3 to 5, Comparative Example 5 A mixture prepared by heating the polypropylene of item 21 shown in Table 2 below to the heating ratio of fertilizer in the same table (cyclohemosan furobe o: and cyclo Pellets were obtained as in Examples 1 and 2, except that 1. of the soluble powder was used, respectively.

Using the obtained pellets, manufacturing a nonwoven fabric, measuring bending resistance and tensile strength, and measuring bending resistance 25 according to Examples 1 and 2.
The tensile strength value at the time was calculated.

The results are shown in Table 2.

As is clear from Tables 1 and 2, the tensile strength of the nonwoven fabric of the present invention at the same softness is higher than that of each comparison side. It can be seen that the tensile strength has been improved.

(Effects of the invention) The nonwoven fabric of the present invention has hardening of the texture due to excessive heat fusion between models (・: Insufficient heat fusion, It is a non-woven fabric that has improved its shortcomings) and has improved tensile strength without causing any problems in texture or texture, so it can be used for medical and sanitary materials such as fading materials for surgical gowns and disposable diapers, and civil engineering materials such as drainage materials and ground improvement materials. It can be suitably used for various purposes including agricultural materials and industrial materials such as oil adsorbents.

that's all

Claims (2)

[Claims] (1) The isotactic pentad fraction is 0.880 or more and 0.930 or less, and the isotactic pentad fraction of the boiling cyclohexane insoluble part and the isotactic pentad fraction of the boiling cyclohexane soluble part A polypropylene nonwoven fabric characterized by using polypropylene having a difference of 0.050 or more. (2) A nonwoven fabric made of polypropylene, characterized in that the polypropylene according to claim 1 is a mixture of two or more types of polypropylene.