JPS61289162A - Production of heat resistant 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] [Industrial Application Field] The present invention relates to a method for producing a heat-resistant nonwoven fabric using undrawn polyphenylene sulfide (hereinafter referred to as "PP8J") fiber as an adhesive element, and the nonwoven fabric obtained by this production method. It is used in a wide range of applications, such as heat-resistant electrical insulation materials of class H or higher that require a high degree of heat resistance, heat-resistant filters, and clothing-related materials that require heat resistance and flame retardancy.

[Conventional technology]

As heat-resistant non-woven fabrics, paper-like non-woven fabrics produced by a wet process are widely known, in which wholly aromatic polyamide short fibers, which are heat-resistant fibers, are mixed with pulp-like particles of the same type. A method for producing a heat-resistant nonwoven fabric using thermocompression bonding using wholly aromatic polyamide fibers as adhesive elements is disclosed.

On the other hand, for PP8 resin, the fiberization technology shown in Japanese Patent Publication No. 52-80609 and Japanese Unexamined Patent Publication No. 58-31112 is known, and PP8 resin is
Heat-resistant needle punch felt using P8 fiber,
Heat-resistant non-woven fabrics made by the spunbond method of 1987-16964 are known.

[Problem that the invention seeks to solve]

Heat-resistant nonwoven fabrics mainly made of fully aromatic polyamide fibers are
Except for the wet method described above, no manufacturing method that does not reduce heat resistance and is suitable for mass production has yet been developed. For example, by utilizing the thermal adhesive properties of undrawn aromatic polyamide fibers71
? ,! ! ! Also, in the manufacturing method, in order to obtain sufficient strength of the nonwoven fabric, heat crushing at a high temperature of 300°C or higher is required, so it is difficult to apply a normal calender etc.
The use of plasticizing solvents such as 2-dimethylpyrrolidone and dimethylformamide has been considered in order to lower the thermocompression bonding temperature, but this also requires processing at higher temperatures than the range applicable to ordinary calenders. Otherwise, a solvent exhaust and recovery device is required, which are both difficult to implement due to poor versatility.

On the other hand, heat-resistant nonwoven fabrics made of PPS fibers, whether short fiber felt made by the needle punch method or long fiber nonwoven fabric made by the spunbond method, are both formed by mechanical entanglement, and it is difficult to bond them by heat fusion. It was thought that

In addition, a method of thermocompression bonding with low melting point thermoplastic fibers such as undrawn polyester fibers, mainly consisting of the above-mentioned heat-resistant fibers, has been put into practical use; however, although this method provides nonwoven fabric strength, the heat resistance decreases. Only unfavorable results have been obtained.

[Means and effects for solving the problems] The present invention uses heat-resistant fibers and undrawn PP8 fibers in a weight ratio of 92:8 to 92:8.
By mixing cotton at a ratio of 20:80 to form a polyester fiber and applying pressure to the undrawn fibers, no special equipment is required, and it can be used for thermocompression bonding of conventional undrawn polyester fibers, etc. It is possible to apply this type of equipment and make it possible to produce nonwoven fabrics with extremely excellent heat resistance.

The heat-resistant fibers used in the present invention may be any heat-resistant resin that has fiber-forming properties, such as wholly aromatic polyamide, P P 8/f! +) Fibers formed from ether ether ketone, fully aromatic polyester, 78-nol thermosetting resin, etc., and inorganic fibers such as glass and metal are considered, but when considering cost and mass production, etc.
Optimally, fully aromatic polyamide fibers or PP8 fibers are utilized. The wholly aromatic polyamide fibers referred to herein refer to poly-m-phenylene isophthalamide fibers and modified products thereof, and the PP8 fibers refer to poly-p-phenylene sulfide fibers and modified products thereof.

The following K is an undrawn PPS fiber applied to the present invention,
When compared with undrawn polyester fibers, which are known layered fibers, these fibers have the drawbacks of being rigid and having low strength, as well as low crimp formation and retention properties, and therefore cannot be used with ordinary card machines, etc. was considered difficult to apply. but,
The present inventor has discovered that it is possible to apply undrawn PP8 fibers to ordinary card machines, etc. by blending 20% or more of the total fibers with heat-resistant fibers having crimps of about 5 to 40 threads/251E1. This is what we discovered. If the blending amount of the heat-resistant fibers having crimps is less than 205%, it is not preferable because the undrawn PPS fibers sink into the carding machine or the like, resulting in poor opening properties. In addition, in order to maintain the strength and shape of the nonwoven fabric, it is necessary to make the blending amount of undrawn fibers at least 8%, and if it is less than 8%, the bonding strength is insufficient and it cannot be put to practical use.

In order to form a uniform bulge, the fineness of all constituent fibers must be on average 1 to 20 deniers, and the fiber length must be on average 25 to LO2f.
Preferably, it is l.

If it is outside these ranges, it will be difficult to open the fibers using a normal card machine or the like, or it will be easy to cause unevenness, which is not preferable.

When blending the cotton, it is preferable to spray a small amount of oil or the like to prevent static electricity.

Although the reason for this is not clear, it is thought that the entanglement of the drawn yarn with the undrawn yarn is stabilized.

The fibers blended in this way can be applied to ordinary nonwoven fabric manufacturing machines, carding methods, airlay methods, etc., and can be extremely easily formed into a cloth.

Next, to explain the method of thermocompression bonding, unstretched PP8
You can find even greater advantages in using .

Most of the undrawn PP8 fibers are amorphous, but about 120
Crystallizes at -140℃ and has a melting point of 275-28
It is known that the temperature is 5°C. Generally, in order to heat-fuse thermoplastic fibers, a temperature range above the softening point and below the melting point is effective, and the unstretched PP used in the present invention
S has a wide contact area of about 125°C to about 270°C that cannot be obtained with other fibers.

However, when contacting was actually carried out under various conditions, it was found that the temperature was about 188 to 257℃, especially 215 to 240℃, when the linear pressure was 3.
It was optimal between 0 and 270 Wctx.

These pressures and temperatures are within the usable range of general-purpose heat presses, heat roll calenders, etc., without the need for special high-temperature, high-pressure equipment, and equipment that has traditionally bonded other fibers by thermocompression. can be used without any modification. In particular, in the method of thermocompression bonding using two rolls,
Despite instant thermocompression bonding, a heat-resistant nonwoven fabric with excellent strength and dimensional stability was obtained without any other special heat treatment. In addition, when heating only from one side, heat-resistant materials such as steel and asbestos, which easily damage the mating roll, are not needed, and production problems can even be eliminated by using elastic materials such as silicone. .

[Example 1] As a heat-resistant fiber, 2 denier, 51 m1 fully aromatic polyamide fiber (manufactured by Teijin ■, trade name "Conex ■")
85%, 15 denier, 51 threads of undrawn PP8 fiber 1
5% was blended using a garnet machine and opened using a card machine so that the fibers were aligned in the direction of web propagation to produce 80 fAt? A woub was formed. Next, thermocompression bonding was carried out using a heated steel roll with a surface temperature of 220° C. on one side and a silicone rubber roll on the other at a line pressure of 100 mm V1 to obtain a heat-resistant nonwoven fabric.

The initial normal physical properties of this nonwoven fabric are shown in Table 1, and the results of the heat-resistant tensile strength deterioration test using the Arrhenius formula are shown in Figure 1. It belongs to Class E as defined by the Japanese government (2013), and has heat resistance equivalent to that of fully aromatic polyamide nonwoven fabrics produced by conventional wet methods, making it useful as a base material with superior impregnability for electrical insulation panels. .

[Example 2] Using the same fibers as used in Example 1, the blending ratio was 50.
150, mix the cotton while spraying a small amount of oil,
After opening, 8 pieces of 150 f to 8 pieces laminated with a cross layer were thermocompressed under the same conditions as in Example 1, and then the woops were reversed and reheat crushed under the same conditions to obtain a thick heat-resistant material. A nonwoven fabric was obtained.

The initial normal physical properties of the obtained nonwoven fabric are shown in Table 1, and the heat resistance tensile strength deterioration test using the Arrhenius method is shown in Figure 1. Regardless, the impregnability of the heat-resistant insulating face, which is a drawback of the fully aromatic polyamide nonwoven fabric produced by the wet method described above, does not deteriorate, and the fabric has excellent impregnability, making it a unique and useful product.

[Example 8] As a heat-resistant fiber, 8.5 denier 51 fl length PPS
Fiber (manufactured by Phillips Petroleum Company).

Using the product name "Rydon ■ Fiber"), it was blended and mixed with lO Denypy and 51u long undrawn PP8 [fiber] at a ratio of 91/9. Next, the fibers are opened so that they are arranged in the direction of travel of the web to form a 40 f/m'' block.
Using the same pair of rolls used in Example 1, thermocompression bonding was carried out at a steel side surface temperature of 240°C and a linear pressure of 70 kq/cm.
A heat-resistant nonwoven fabric was obtained.

The properties of this nonwoven fabric are also shown in Table 1 and Figure 1, and it has heat resistance that meets Class H standards, and is useful as a reinforcing material for mica tape, which requires strength only in the longitudinal direction. It was something.

[Example 4] Using the same fibers as those used in Example 3, a tooy β cross layer laminated with a blending ratio of 80/70 was obtained. Next, this fabric was passed through the same pair of rolls as in Example 1 twice under conditions of a temperature of 240° C. and a linear pressure of 150 Was, with the front and back sides reversed, to obtain a dense heat-resistant nonwoven fabric.

As shown in Table 1 and FIG. 1, the obtained nonwoven fabric also complies with Class H, and due to its dense structure, it has a sufficiently high withstand voltage even without impregnation with a heat-resistant electrical insulation panel, etc. It has the unprecedented advantage of being able to be used alone, and is useful for electrical insulation tapes and the like. In addition, since PP8 resin has excellent chemical resistance that wholly aromatic polyamide does not have, it is extremely useful for various heat-resistant battery separators, etc., for which it has been difficult to apply wholly aromatic polyamide nonwoven fabrics. .

[Comparative Example 1] The PPB fiber used in Examples 8 and 4 was used as the heat-resistant fiber, and the undrawn aromatic polyamide fiber of 5 denier and 51 mm was used as the contact layer fiber, and the blending ratio was 80. /7
Create a laminated tube using 0 701β glue A slay,
Two steel rolls that can be heated on both sides were subjected to heat and pressure under the conditions of a roll surface temperature of 290° C. and a linear pressure cuff of 01.

However, although the fabric was crushed thin and compacted, there was no bonding between the fibers, and therefore it lacked the strength and retention properties of a nonwoven fabric.

[Comparative Example 2] A fiber made of a polyamide copolymer of 8 denier and 51 WII length (manufactured by Dupon', trade name: I'QIAN)
115% of AJ was blended to form 801 to 1.

In this case, the surface temperature was 245t using the same pair of rolls as in the example.
, thermocompression bonding was carried out at a linear pressure of 150 kv'cs to obtain a heat-resistant nonwoven fabric. As shown in Table IK, this nonwoven fabric had very wet initial normal characteristics, but as shown in Figure 1,
It was clearly inferior in heat resistance and could not be applied to type H.

[Reference Example 1] As a reference example, the same test as in the example was conducted on one product of DuPont's heat-resistant paper (trade name: Nomex Paper J1gmi), and the results are shown in Table 1 and FIG.

〔effect〕

As shown in the examples, the present invention can be realized very easily and with a high degree of heat resistance by proactively employing undrawn PPS fibers as adhesive fibers, which could not be used in the prior art. The nonwoven fabric obtained from the present invention has all the properties of PP8 resin, such as heat resistance, chemical resistance, flame resistance, and electrical insulation, so it can be used in a wide range of applications. This will meet the needs of the industry.

[Brief explanation of drawings]

Figure 1 shows the results of a heat-resistant tensile strength deterioration test using the Arrhenius equation.
,4. This is the order of Comparative Example 2. Patent applicant Nippon Vilene Co., Ltd. [41Diagram 1. In the Ashinian style, J7 drunkenness is considered (
t, rO-/- tension l Shinsen H tan ε me rescue 1 san 1 de Tsukasa Z Te Ding - 11

Claims (4)

[Claims] (1) A web is formed by blending heat-resistant fibers and undrawn polyphenylene sulfide fibers at a weight ratio of 92:8 to 20:80, and the undrawn fibers are plasticized under pressure to produce a fusing effect. A method for producing a heat-resistant nonwoven fabric, characterized by carrying out thermocompression bonding under temperature conditions. (2) A method for producing a heat-resistant nonwoven fabric according to claim 1, using drawn polyphenylene sulfide fibers as the heat-resistant fibers. (3) The method for producing a heat-resistant nonwoven fabric according to claim 1, using wholly aromatic polyamide fibers as the heat-resistant fibers. (4) The method for producing a heat-resistant nonwoven fabric according to claim 1, wherein the heat-resistant fibers and the undrawn polyphenylene sulfide fibers are staple fibers having an average fineness of 1 to 20 deniers and an average fiber length of 25 to 102 mm.