JPH10279680A - Heat-resistant resin, molded item therof, fiber for bag filter, and production of fiber for bag filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant resin which is excellent esp. in resistances to heat and chemicals. SOLUTION: This resin is a polyamide or polyimide resin which contains 4,4'-diaminodiphenylmethane residues as amine residues and has a logarithmic viscosity (in N-methyl-2-pyrrolidone at 25 deg.C) of 0.65 dl/g or higher and a ratio of wt. average mol.wt. (Mw) to number average mol.wt. (Mn) of 2.6 or lower. Both the molded item and the fiber for bag filters mainly comprise the resin and have a 0.5 wt.% insolubles to N-methyl-2-pyrrolidone at 100 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant resin comprising a polyamideimide or a polyimide resin having excellent heat resistance and chemical resistance, and a molded article containing the heat-resistant resin as a main component, particularly a fiber for a bag filter, Relates to a method for producing the fiber for a bag filter. In particular, the present invention relates to a high-temperature bag filter fiber used in a smoke exhaust facility and the like and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, polytetrafluoroethylene has been used as a heat-resistant fiber for a bag filter, but there has been a problem that the production cost is high. Also, aramid fibers are used. For example, para-type aramid fibers synthesized from terephthalic acid chloride and p-phenylenediamine, and meta-type aramid fibers synthesized from isophthalic acid chloride and m-phenylenediamine are typical examples.

Further, polyimide or polyamide imide is known as a typical heat-resistant polymer. For example, poly (4,4′-oxydiphenylenepyromellitimide), polyamideimide synthesized from trimellitic anhydride and diaminodiphenylmethane, and the like can be mentioned. However, these polyamides, polyimides or polyamide imides produced by conventional methods are not satisfactory in chemical resistance and oxidation resistance at high temperatures.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a high-temperature bag filter which is used continuously at 260 ° C. or higher. It is an object of the present invention to provide a suitable heat-resistant resin having excellent long-term heat resistance and chemical resistance, and a fiber for a bag filter containing the heat-resistant resin as a main component.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above-mentioned problems, and as a result, have found that a polyamideimide or polyimide containing at least a 4,4′-diaminodiphenylmethane residue as an amine component, -Methyl-
The logarithmic viscosity measured at 25 ° C. in 2-pyrrolidone is 0.6.
A heat-resistant resin comprising a polyamideimide or a polyimide resin having a weight average molecular weight (Mw) and a number average molecular weight (Mn) of not more than 2.6 and having a weight average molecular weight (Mw) and a number average molecular weight (Mn) of 2.6 or less has a high heat resistance and a low heat resistance. They have found that they have a flammable and chemical resistant structure, and have completed the present invention. Further, the heat-resistant resin as described above is easily converted to a high molecular weight, and is soluble in an organic solvent. After the heat-resistant resin is dry-spun or wet-spun, it is stretched and / or heat-set at 350 ° C. or more. Alternatively, it has been found that the above object is achieved by performing a heat treatment at 180 ° C. or higher after fiber formation to insolubilize the organic solvent.

Although the heat-resistant resin of the present invention can be synthesized by ordinary melt polymerization or solution polymerization, solution polymerization using diisocyanate is advantageous in terms of cost.

As a diamine component used for synthesizing a heat-resistant resin, diaminodiphenylmethane or its diisocyanate is preferable in terms of heat resistance, chemical resistance, cost and the like. Further, the heat treatment during or after the formation of the fiber is preferable because a partially crosslinked structure which is considered to be accompanied by the hydrogen abstraction reaction of the methylene bond is easily formed and the high-temperature chemical resistance is improved.

As long as the heat resistance and high-temperature chemical resistance of the present invention are not impaired, some of the diamine components are aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine and diaminodiamine. Aromatic diamines such as diphenyl ether, tolylenediamine and o-tolidine, alicyclic diamines such as cyclohexyldiamine and diaminodicyclohexylmethane, and diisocyanates thereof are used. Among these, tolylenediamine or its diisocyanate is preferred from the viewpoint of heat resistance and chemical resistance.

Examples of the acid component include pyromellitic anhydride, benzophenonetetracarboxylic anhydride, 3,3
3 ′, 4,4′-diphenyltetracarboxylic anhydride,
Aromatic polycarboxylic anhydrides such as trimellitic anhydride, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and cyclohexanedicarboxylic acid And alicyclic dicarboxylic acids such as dimer acid. Among these, trimellitic anhydride and benzophenonetetracarboxylic anhydride are preferred from the viewpoint of solubility, heat resistance, chemical resistance, and the like, and a part thereof can be replaced with another acid anhydride or dicarboxylic acid. .

To synthesize polyamideimide or polyimide by the isocyanate method, the above isocyanate component and acid component are combined with N-methyl-2-pyrrolidone, dimethylacetamide, dimethylformamide, 1,3-dimethyl-2-imidazolidinone or the like. 70 in polar solvent solution
React at ~ 200 ° C. If necessary, the reaction can be accelerated by adding a catalyst such as an alkali metal, an alkaline earth metal, a salt thereof, or an amine.

In the above method, the type of each component to be used is appropriately selected depending on the desired physical properties of the heat-resistant resin of the present invention. Diaminodiphenylmethane or diphenylmethane diisocyanate as the main amine component,
When the logarithmic viscosity is 0.65 or more and the molecular weight distribution (Mw / Mn) is 2.6 or less, the obtained polyamideimide or polyimide has good spinnability and excellent strength and elongation based on appropriate solubility. Show.

The logarithmic viscosity of the heat-resistant resin of the present invention is 0.65 dl / g or more as described above, and preferably 0.8 dl / g.
/ G or more. When the logarithmic viscosity is less than 0.65 dl / g, heat resistance and high-temperature chemical resistance are not sufficient. Also, Mw /
Mn is 2.6 or less as described above, and preferably 2.0 or less. If Mw / Mn is greater than 2.6, the polymer becomes brittle, and the amount of cotton falling during felting in the process of manufacturing a bag filter increases, and the yield decreases.

When the logarithmic viscosity is 0.65 dl / g or more, Mw /
In order to achieve Mn of 2.6 or less, 1,3-dimethyl-2-imidazolidinone is used as the polymerization agent, potassium fluoride is used as the catalyst, and the initial polymerization is performed at a high concentration of 30 to 40%, Perform at a low temperature of 120 ° C, then 15-2
It is preferably carried out at a low concentration of 5% and a high temperature of 160 to 200 ° C.

The heat-resistant resin of the present invention can be processed into molded articles of various forms using it as a main component. Examples of the molded article in the present invention include a fiber, a film, and an injection molded article material. In particular, it is suitable as a main component of the fiber for bag filters.

When the heat-resistant resin of the present invention is processed into a molded product, various additives can be added in appropriate amounts. For example, in the case of a fiber, it is preferable to mix an appropriate amount of an oil agent, an antistatic agent, a coloring agent, an antioxidant, an inorganic filler and the like in order to improve the properties and processability.

Preferably, the molded article or the bag filter fiber containing the heat-resistant resin as a main component has an insoluble content in N-methyl-2-pyrrolidone of 0.5% by weight or more, more preferably 1% by weight. % Or more. By making the insoluble content 0.5% by weight or more, heat resistance and chemical resistance can be further improved.

In order to increase the insoluble content in N-methyl-2-pyrrolidone to 0.5% by weight or more, the above heat-resistant resin is spun and stretched and / or heat-set at 350 ° C. or more after spinning. The stretching in the following can be achieved by performing a heat treatment in the fiber forming step. The heat treatment is performed at a temperature of 180 ° C. or more, preferably 200 ° C. or more, for several seconds to several tens of hours, depending on the desired physical properties. When the heat treatment temperature is 180 ° C. or lower, heat resistance and high-temperature chemical resistance are not sufficiently exhibited.

Further, N-methyl-2 by the above heat treatment is used.
In order to make the insolubilization treatment on pyrrolidone more effective, a crosslinking agent such as an epoxy resin or a melamine resin may be blended in advance with polyamideimide or polyimide, and the resulting mixture may be spun and stretched for heat treatment. As the cross-linking agent, a phenol novolak-type polyfunctional epoxy resin is preferable, and its compounding amount is 1 to 30% by weight, preferably 2.5 to 20% by weight.

The heat-resistant resin of the present invention can be converted into a fiber by any of dry spinning and wet spinning using conventional equipment. Here, the dry spinning method is a method in which a polymer solution is discharged into a heated gas, and then the solvent is removed to solidify and fiberize. On the other hand, the wet spinning method is a method in which a polymer solution is discharged into a coagulation bath, and then the solvent is removed to solidify and fiberize.

In any of the dry spinning method and the wet spinning method, the solvent for dissolving the heat-resistant resin of the present invention includes, for example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2. Polar solvents such as pyrrolidone, dimethylsulfoxide, dimethylurea and the like are suitable, and the following solvents can be used by mixing with these polar solvents. For example, toluene, hydrocarbon solvents such as xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ketone solvents such as cyclohexanone,
Dioxane, ethylene glycol dimethyl ether, ether solvents such as tetrahydrofuran, ethyl acetate,
Examples include ester solvents such as n-butyl acetate and γ-butyrolactone.

When fiberization is performed by a wet spinning method, water is most preferable as a coagulation bath. However, it is also possible to use a solvent that is a non-solvent for the heat-resistant resin and is compatible with the solvent.

The polyamide-imide or polyimide fiber of the present invention can be used in an undrawn state depending on the application. However, in order to improve the strength, heat resistance, and chemical resistance (high-temperature heat resistance), drawing and heat treatment are performed. It is effective to finely and partially crosslink the fiber structure. When the fiber structure becomes dense, it is possible to prevent the mist from boiling and evaporating in the fiber and at the fiber surface at high temperature, thereby preventing the fiber structure from being destroyed.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the following examples, characteristics of the obtained polyamideimide or polyimide fiber were measured by the following methods.

1. 0.5 g of the logarithmic viscosity polymer was added to N-methyl-2-pyrrolidone 100
It was dissolved in ml and measured at 25 ° C.

2. Tensile strength at break, using Tensilon manufactured by Toyo Baldwin Co., Ltd.
The measurement was performed at a pulling speed of 20 mm / min in an atmosphere of 55 ° C. and 55% RH.

3. High-temperature chemical resistance test A single yarn is immersed in a solution of a predetermined concentration of the chemical to be tested, wound around a glass mount, placed in a Teflon bottle with a lid, and sealed with a lid. Put in the dryer for 2 hours. After cooling, the gantry was taken out, washed repeatedly with water, and the single yarn was dried. Thereafter, the single yarn was subjected to a tensile strength / elongation test, and the high-temperature chemical resistance was evaluated based on the retention of each physical property.

4. Measurement of insoluble content About 1 g of precisely weighed single yarn was immersed in 50 ml of N-methyl-2-pyrrolidone at 100 ° C. for 2 hours, filtered through a glass filter, and the residue was washed with acetone and dried under vacuum. Was weighed.

Example 1 192 g of trimellitic anhydride and 25 of diphenylmethane diisocyanate were placed in a reaction vessel.
3 g, 1.2 g of potassium fluoride and 1,427 g of 1,3-dimethyl-2-imidazolidinone were charged, and the temperature was raised to 200 ° C. over 1.5 hours with stirring. 200 ° C
After reacting for 7 hours, the cooled polymer solution was poured into a large amount of water to coagulate, washed sufficiently with water and dried. The logarithmic viscosity of the obtained polymer is 0.95 dl / g, Mw / M
n was 2.3.

A solution prepared by dissolving 200 g of the dried polymer in 800 g of N, N-dimethylformamide was extruded from the pores and passed through a dry spinning machine having a drying furnace length of 1.5 m and a furnace temperature of 270 ° C. at 220 m / min at 15 denier (d). ) Was obtained. The undrawn yarn was passed through a heating zone (1 m) at 400 ° C. in air at a speed of 29 m / min and drawn 5 times. Table 1 shows the results of the high-temperature chemical resistance of the drawn yarn (3d).

Comparative Example 1 Commercially available polyimide fiber (2
d: Lenzing Co, Ltd., P-84) is also shown in Table 1.

[0031]

[Table 1]

(Comparative Example 2) The unstretched yarn that was dry-spun in Example 1 was heated in air at 320 ° C in a heating zone (1 m) at 29 m / m.
The film was stretched 3.5 times at a speed of 1 minute. 10 of this drawn yarn
Table 2 shows the results of insoluble matter in NMP at 0 ° C. and high-temperature chemical resistance to 7% sulfuric acid.

(Examples 2 to 5) When the drawn yarn of Comparative Example 2 and the commercially available polyimide fiber of Comparative Example 1 were heat-treated under various conditions, the high-temperature chemical resistance to NMP at 100 ° C. and 7% sulfuric acid was obtained. Table 2 shows the results.

[0034]

[Table 2]

Comparative Example 4 194 g of trimellitic anhydride and 25 of diphenylmethane diisocyanate were placed in a reaction vessel.
0 g and 831 g of N-methyl-2-pyrrolidone were charged and heated to 200 ° C. over 1.5 hours while stirring.
After reacting at 200 ° C. for 5 hours, the mixture was cooled, and 1187 g of N
The solution diluted by adding -methyl-2-pyrrolidone was poured into a large amount of water to coagulate, sufficiently washed with water, and dried.
The logarithmic viscosity of the obtained polymer is 0.56 dg / l,
w / Mn was 3.0.

A solution prepared by dissolving 200 g of the dried polymer in 800 g of N, N-dimethylformamide was subjected to dry spinning and stretching under the same conditions as in Example 1 to obtain a drawn yarn of about 3d. When a felt was prepared by a needle punch method using the drawn yarn, much cotton was dropped and the yield was poor. Table 3 shows the results of high-temperature chemical resistance of the drawn yarn to 7% sulfuric acid.

Example 8 192 g of trimellitic anhydride and 25 of diphenylmethane diisocyanate were placed in a reaction vessel.
0 g, potassium fluoride 1.2 g and N-methyl-2-
531 g of pyrrolidone was charged, the temperature was raised to 100 ° C. with stirring, and the reaction was carried out for 1.5 hours. Then, 531 g of N-methyl-2-pyrrolidone was added, and the temperature was raised to 200 ° C. in about 1 hour and the reaction was continued for 7 hours I let it. Thereafter, while cooling, 944
The solution diluted with g of N-methyl-2-pyrrolidone was poured into a large amount of water to coagulate, washed sufficiently with water and dried.
The logarithmic viscosity of the obtained polymer is 0.78 dl / g, Mw /
Mn was 2.4.

A solution prepared by dissolving 200 g of this polymer in 800 g of N, N-dimethylformamide was subjected to dry spinning and stretching under the same conditions as in Example 1 to obtain a drawn yarn of about 3d. Table 3 shows the results of the high-temperature chemical resistance of the drawn yarn to 7% sulfuric acid.
Shown in

[0039]

[Table 3]

[0040]

According to the present invention, a high-strength heat-resistant resin made of polyamideimide or polyimide having excellent heat resistance and chemical resistance, and a molded product containing the same as a main component, particularly a fiber for a bag filter, can be easily prepared. It can be obtained inexpensively by a simple method.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroki Yamaguchi 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd. Research Laboratory

Claims (7)

[Claims] 1. An amine component comprising at least 4,4′-
Polyamideimide or polyimide containing a diaminodiphenylmethane residue, having a logarithmic viscosity of 0.65 dl / g or more measured at 25 ° C. in N-methyl-2-pyrrolidone, and having a weight average molecular weight (Mw) and a number average molecular weight (M
A heat-resistant resin comprising a polyamideimide or polyimide resin having a ratio (Mw / Mn) of n) of 2.6 or less. 2. A molded product comprising the heat-resistant resin according to claim 1 as a main component. 3. The molded article according to claim 2, wherein the insoluble content in N-methyl-2-pyrrolidone at 100 ° C. is 0.5% by weight or more. 4. A fiber for a bag filter comprising the heat-resistant resin according to claim 1 as a main component. 5. The fiber for a bag filter according to claim 4, wherein the insoluble content in N-methyl-2-pyrrolidone at 100 ° C. is 0.5% by weight or more. 6. The bag filter according to claim 4, wherein the heat-resistant resin according to claim 1 is dry-spun or wet-spun and then stretched and / or heat-set at 350 ° C. or more. Fiber manufacturing method. 7. The method for producing a fiber for a bag filter according to claim 4, wherein the heat-resistant resin according to claim 1 is subjected to a heat treatment at 180 ° C. or more in the fiber forming step.