JPS58144153A - Production of armatic polyamide 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 The present invention is directed to a method for producing an aromatic polyamide nonwoven fabric, and its purpose is to provide excellent heat resistance, flame retardance, and
Fl! ml, vI41iThe objective is to provide an aromatic polyamide nonwoven fabric with excellent smoothness.

Traditionally, it has been widely used to manufacture nonwoven fabrics by combining or entangling synthetic fibers such as polyester and Nain in an appropriate manner as a base material, but these products lack heat resistance and flammability. K.

41. Building materials and internal bond materials that require heat resistance and flame retardancy.

It is difficult to use it in fields such as electrical insulation materials and materials with mixed content.
It is. It is known that paper-like materials made of aromatic polyamides, particularly polymetaphenylene inphthalamide, can be effectively used to meet such requirements for heat resistance and flame retardancy. For example, it has been disclosed that a polymetaphenylene isophthalamide lacquer solution is dispersed in an aqueous solution to create a pulp with a specific shape, and this pulp and fibers are mixed in water, dried, and heated and pressurized (Japanese Patent Publication No. -1185 publication). However, although this method yields a paper-like material with a dense surface structure, it has the disadvantage of having voids inside. Furthermore, since the impregnating property is poor, when used for insulating material applications that require the use of insulating varnishes and insulation ponds, it is not desirable because the impregnating property is not required, resulting in a decrease in dielectric strength and a shortening of the life of the equipment.

On the other hand, as a method for obtaining a highly impregnable aromatic polyamide nonwoven fabric, a thermoplastic polymer (polyamide, polyester, etc.) is used as a binder.

(it) 2t boxy polymer.

(iii) Aromatic polyamide powder or.

(1v) A method using aromatic polyamide low-orientation low-crystallization fibers is known.

However, the nonwoven fabrics obtained in (1) and (1) have insufficient heat resistance. Furthermore, although the nonwoven fabrics obtained in (iii) and (lv) have sufficient heat resistance, very high temperature and pressure are required in order to develop satisfactory mechanical properties.

To make matters worse, the surface density and smoothness of the obtained nonwoven fabric is insufficient, and it is necessary to improve the density and smoothness of both surfaces by applying adhesive or surface coating to the nonwoven fabric. Not suitable for this purpose.

The present inventors have conducted intensive studies to obtain an aromatic polyamide nonwoven fabric with excellent impregnability, surface writeability, and smoothness without impairing the heat resistance and flammability of the aromatic polyamide material. It has been reached.

That is, the present invention involves attaching aromatic polyamide polymer particles and a polar amide solvent and/or water to a web made of aromatic polyamide fibers, and then subjecting the web to hot-pressure processing.*
* This is a method for producing aromatic polyamide nonwoven fabric.

The aromatic polyamide referred to in the present invention is the following (1).

Consisting of repeating units of (2) and (3) -Co -Ar, -Co ---.= (1) R3 Here, R1, R1, and R, may be the same or different and are hydrogen atoms or have 3 carbon atoms. The following furkyl groups are shown. Substantive K (1) and +21 consist of equimolar. (3) is (1)
and (2) do not necessarily have to be included at the same time. Ar, , Ar, , Ar, are aromatic residues and may be the same or different.

A typical example of Ar, , Ar, , and Mur is paraphenylene.

Metaphenylene and biphenylene are shown below (residues represented by formula 41).

Here, R6 is a residue selected from a hydrogen atom or an alkyl group having 3 or less carbon atoms.

Preferred aromatic polyamides are Ar, l Ar,
e "s is selected from paraphenylene or metaphenylene. More preferably, it consists of +11 and (2),
This is the case for Ar, , Ar, cametaphenylene or paraphenylene. Most preferably +11 and (2
), where Ar, and Ar are both metaphenylene.

Next, the outline of the method for manufacturing the fiber used in the present invention will be described below.

There are several known methods for producing polymetaphenylene isophthalamide fibers, but the method for producing the fibers used in the present invention involves extruding a spinning solution that dissolves polymetaphenine/inphthalamide into a coagulating solution to form a fiber. Even if the product is obtained by washing with water, the product is obtained after the process of stretching in water, and then the process is followed by a stretching heat treatment at a temperature higher than the glass transition temperature. It may be a process of doing so.

That is, the aromatic polyamide fiber used in the present invention is
Whether it is an unstretched unprocessed fiber made of aromatic polyamide or an oriented low-crystallization fiber such as a drawn unheated fiber,
The fibers may be highly oriented and highly crystallized fibers obtained by drawing heat treatment, or may be fibers made of a mixture of two or more thereof.

In the present invention, it is also possible to use a small proportion of other heat-resistant fibers in combination with the aromatic polyamide fibers, such as aromatic polyester fibers, carbon fibers, inorganic fibers, glass fibers, metal fibers, etc. .

The web referred to in the present invention refers to a sheet formed using conventional web forming equipment, and specifically,
A method in which crimped staples are opened into a sheet using a card machine such as a flat card or roller card, and a laminated tow of long fibers is spread in the width direction using a pair of tapered belts with five needles. The so-called long fiber tow opening method to obtain a sheet-like material by
A sheet-like product obtained by dispersing 0%1 degree short fibers in water or air to obtain a sheet-like product.

The aromatic polyamide polymer particles used in the present invention are particles made of the above-mentioned wholly aromatic polyamide, preferably particles in which 70 moles or more of repeating units are made of a copolymer made of polymetaphenylene isophthalamide. It is. These are suitably used to act as a binder by heating and pressurizing. In this polymetaphenylene isophthalamide, aromatic amide units such as paraphenylene terephthalamide and paraphenylene terephthalamide are suitable as components that can be copolymerized at a rate of 30 mole droplets.

However, if the copolymerization ratio is 30 moles or more, it is not preferable because a paper-like material with excellent heat resistance cannot be obtained.

The polymer particles used in the present invention are preferably those obtained by interfacial polymerization method (see Japanese Patent Publication No. 35-13247, IK) or oligomer polymerization method (see Japanese Patent Publication No. 47-1086S). Polymer particles obtained by dissolving a polymer in a solvent and adding the resulting solution to water while stirring may also be used. In addition, the particle size of the Shigetani body particles is 0.1 to 10
00μ, preferably o, i to 500μ is appropriate. 1
If the particle size exceeds 0.000, the particle size is too large, making it difficult to disperse uniformly in the substrate, and the paper-like surface after hot-press processing becomes non-uniform, which is undesirable. On the other hand, particles smaller than 0.1 μm are undesirable because they are difficult to handle.

In the present invention, the polar amide solvent, N-methyl-2-
Pyrrolidone, N,N-dimethylformamide, N
, N dimethylacetamide, dimethyl sulfoxide hexamethylphosphoramide', tetramethyl III, N-
Methyl caprolactam.

Examples include N-methylpiperidine and mixtures thereof.

Said polar 7 mido solvent alone, its water 11! A plasticizer made of liquid or water is applied to a web made of aromatic polyamide fibers. When the oxidizing agent is a polar amide solvent or an aqueous solution thereof, it is appropriate that the adhesion amount in terms of the polar amide solvent is 1 to 100% by weight based on the web. However, in the case of a polar amide aqueous solution, the 111 degrees should be selected appropriately.
It is preferable to reduce the amount of bonding with high troweling.

If the amount of adhesion is less than about 1% by weight, the mechanical properties 1 surface smoothness and density after hot-pressure processing will be insufficient, while if it is more than about 1% by weight, a large amount of solvent will remain in the nonwoven fabric. , as well as a large amount of energy loss during Shimada processing, which is undesirable.

When the plasticizer is water, the amount of the plasticizer attached is preferably 10 to 150% by weight based on the web. The amount of water attached is about 1 oe
If it is less than about 150% by weight, the mechanical properties, surface smoothness, and density after hot-pressing processing will be insufficient. On the other hand, if it is more than about 150% by weight, excessive water will cool the roll during hot-pressing processing, resulting in energy loss. This is not desirable as it results in loss.

Next, the amount of polymer particles attached to the web is 1 to 100.
% by weight. The amount of mosquito particles attached is approximately 1% by weight.
If it is less than 1, the effect as an adhesive is insufficient;
If the weight exceeds 0.00 weight, the resulting nonwoven fabric will become hard and brittle, which is undesirable.

The method of attaching the aromatic polyamide polymer particles and the obfuscating agent consisting of a polar 7-amide solvent and/or water to the web can be a method commonly used industrially that can uniformly attach the particles to the web. For example, a spray method or an impregnation method can be used.

The hot-press processing conditions in the present invention are influenced by the type and type of aromatic polyamide fibers constituting the web, and the type and amount of polar amide solvent attached to the web, so it is best to select them appropriately in practice. Usually using a hot pressure roll, temperature 150-400℃, pressure 10-1000 kJ/
αG, processing speed (paper passing speed [)] 3 m/min or more.

If the temperature is lower than about 150°C, the material is aromatic polyamide fiber, so the fusion properties are low and sufficient mechanical properties cannot be obtained. On the other hand, if it is higher than about 400°C, the paper passing speed and However, this is not preferable since the solvent adhering to the web tends to scatter before pressing, resulting in uneven fusion and yellowing and deterioration of the resulting nonwoven fabric.

If the pressure is too low, fusion will be insufficient. It doesn't matter how high it is, but it is wasteful in terms of energy, so it is usually preferable to set it to s o o o kg/lx.

If the paper passing speed is slower than about 311/cm, the solvent adhering to the web will scatter or be unevenly distributed, resulting in a decrease in fusion properties and non-uniformity, which is not preferable. Note that the hot-pressing method is preferably carried out using two or more hot-pressing rolls.

In the flat press method, the solvent attached to the web is trapped during pressing, so the resulting nonwoven fabric is unfavorable because it lacks surface smoothness.

Since the non-woven fabric obtained by the present invention is composed of fibers, it is essentially voidless, and its impregnation properties are significantly different from synthetic paper obtained using pulp. In addition, since the polar amide solvent and/or □ are subjected to hot-pressure processing with water attached, the heat-pressure processing conditions are relaxed, and the denseness and surface smoothness of the resulting nonwoven fabric are greatly improved. In addition, in the nonwoven fabric subjected to heat and pressure processing, the residual rate of attached solvent in the fabric is extremely low, and the heat resistance of the material is not impaired at all.

The nonwoven fabric obtained from KL-C is expected to be used in lightweight composite materials such as electrical insulation materials, building materials, inner acupuncture materials, release sheets, and even hallacams.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, the intrinsic viscosity of the polymer in the examples was determined using concentrated sulfuric acid at a concentration of 0.
．． 5ji/d@, and the temperature was constant at 1!130°C.

In addition, oil impregnation was determined by vacuum drying a 5121 square sample at 25°C and atmospheric pressure, placing it on the oil surface of insulating oil No. 1 (JIS standard), and measuring the time until the insulating oil was coated on the sample surface. This was carried out by

Example 1-5 Using tetrahydrofuran as a polymerization solvent, isophthalic acid chloride and terephthalic acid chloride.

A copolymer consisting of 90 moles of polymetaphenylene isophthalamide component and 10 moles of polymetaphenylene terephthalamide component with an intrinsic viscosity of 1.9 was produced using metaphenylene diamine by an interfacial polymerization method (% Publication No. 47-10863). was obtained in the form of particles.

The particle size after separation, washing and drying was 20-300μ.

On the other hand, wet spinning was carried out using N-methyl-2-pyrrolidone dope of polymetaphenylene isophthalamide having an intrinsic viscosity of 1.8, crimping was applied after washing and drying, and the single yarn fineness was 1.8. !
Short fibers with a cut length of 51% were obtained (fiber-M).

In addition, after wet spinning using Dope and washing with water, 2
．． It was stretched 7 times and crimped after drying to obtain IIK short fibers with a single yarn fineness of 1.5 de and a cut length of 51% (Fiber-F).
).

Furthermore, KJII dope was used for wet spinning, washed with water, stretched to 2.7 times in a water bath, dried, and then further stretched to 1.3 times on a hot plate. Short fibers with a cutting length of 51 and a cut length of 51 were obtained (fiber-R).

After pre-wiring a blend of three types of fibers in various proportions using a single scatcher, two flat cards were prepared.
A web is formed on a belt conveyor using a cross-laid webber, and then a needle with a needle density of 84 pieces/csf is applied using a needle machine using L-barb needles to obtain a fabric weight of so.
g/* entangled sea urchin/ was obtained. A suspension of 3 parts of N-methyl-2-biaridone, 97 parts of water, and aromatic polyamide polymer particles was deposited on the front and back surfaces of this web using a spray device.

Then, using a hot pressure roll at a temperature of 280°C and a linear pressure of 4ookg.
/α and a speed of 8wt for 1 minute, and was continuously rolled and sucked while reducing the tension. The physical properties of the obtained nonwoven fabric are
Shown in the table. The strength elongation was determined using an Instron measuring machine with a chuck interval of 20 am+sample width of 1.5 aa and a head speed of 103/min. The surface smoothness of the nonwoven fabric was measured by observing the surface unevenness and fluff of the surface and cross section of the nonwoven fabric using a microscope.

Comparative Examples 1-5 Implementation? 61-4, 10 parts of aromatic polyamide polymer particles alone were used instead of a suspension of 39 parts of N-methyl-2-pyrrolidone, 97 parts of water, and 10 parts of aromatic polyamide polymer particles using a powder coating gun. A nonwoven fabric was obtained by heat-pressing processing in exactly the same manner except that the nonwoven fabric was attached to the cloth. Table 1 shows the pleasantness of the obtained nonwoven fabric.

Table 1 * O: 2 unevenness, no fuzzing, good ○ to △; no unevenness, some fuzzing ×: insufficient fusion, a lot of fuzzing Examples 6 to B, Comparative Example 6 R/F = 4 created in the same manner as Example 4 For a web 100@ with a basis weight of 8511/d and a ratio of /6,
A suspension consisting of 5 parts of N-methyl-2-pyrrolidone, 95 parts of water, and 20 parts of aromatic polyamide polymer particles was sprayed with varying amounts of axillary fluid applied to the web, and then heated to a temperature of 2.
25℃, linear pressure 400 kll/lxG, speed to@,
The film was continuously wound up under the conditions of 1/2 min while applying tension to an extent that wrinkles did not occur.

Table 2 shows the pleasantness of the obtained nonwoven fabric.

Table 2

Claims (1)

[Scope of Claims] L An aromatic product characterized by adhering aromatic polyamide polymer particles and a lubricant consisting of a K11lk amide solvent and/or water to a web made of aromatic polyamide fibers, and then subjecting the web to hot-pressure processing. Method for manufacturing polyamide nonwoven fabric. 1. The method for producing an aromatic polyamide nonwoven fabric according to claim 1, wherein the aromatic polyamide fibers constituting the web are made of polymetaphenylene isophthalamide. A method for producing an aromatic polyamide nonwoven fabric according to claim 1, wherein the aromatic polyamide polymer particles are made of polymetaphenylene isophthalamide. Table: When the hazy agent is water and its adhesion amount is 1
The method for producing an aromatic polyamide nonwoven fabric according to claim 1, which has a weight of 0 to 150 weight. The weighting agent is a polar amide solvent or its aqueous solution.
The adhesion amount converted to polar amide SS is 1 to Z on the web.
The method for producing an aromatic polyamide nonwoven fabric according to claim 1, wherein the weight/weight is -. 11. The method for producing an aromatic polyamide nonwoven fabric according to claim 3, wherein the amount of the aromatic polyamide polymer particles adhered to the web is 1 to 100% by weight. ), heat pressure processing using a heat pressure tool at a temperature of 150 to 400
The method for producing an aromatic polyamide nonwoven fabric according to claim 1, which is carried out under the following conditions: temperature, pressure of 10 to 400 hours/G, and processing speed of 3 dew/minute or more.