JPS6131203B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to aromatic polyamide fibers, particularly polymetaphenylene isophthalamide fibers, having improved solvent resistance and excellent heat resistance. <Prior art> Aromatic polyamides have a higher softening point and melting point than aliphatic polyamides, which are known to be suitable for a wide range of applications, and have low strength retention at high temperatures, morphological stability, and thermal decomposition. It not only has excellent heat resistance, flame resistance, and flame retardancy, but also has extremely desirable physical and chemical properties such as chemical resistance, electrical properties, and mechanical properties such as strength and Young's modulus. It is suitable for use in heat-resistant, flame-retardant, flame-retardant fibers, high-strength, high-Young's-modulus fibers, film molding materials, paper-like materials, etc. Therefore, aromatic polyamide fibers are widely used as electrical insulating materials for motors and transformers, industrial applications such as filter bags and heat insulating materials for heating tubes, and flame-retardant and flame-retardant protective clothing. However, depending on the field in which aromatic polyamide is used, acid resistance against sulfuric acid and the like is strongly required, and existing aromatic polyamide fibers are insufficient. By the way, it has been proposed to improve the heat resistance of polyester fibers such as polyethylene terephthalate by incorporating a specific crosslinking compound into the polymer and subjecting it to crosslinking treatment. ), even if this method is directly applied to wholly aromatic polyamide fibers, especially polymetaphenylene isophthalamide fibers, the effect is poor. <Object of the Invention> The main object of the present invention is to provide a polymetaphenylene isophthalamide fiber that has significantly improved heat resistance and acid resistance compared to conventional polymetaphenylene isophthalamide fibers. <Structure of the Invention> The aromatic polyamide fiber of the present invention that can achieve the above object is a fiber mainly composed of a polymetaphenylene isophthalamide-based aromatic polyamide, and the aromatic polyamide has the below-mentioned (i) or Treatment with heat, ultraviolet rays, or electron beams in a state containing at least one of cyanuric acid or isocyanuric acid derivatives, bismaleimide compounds, or glycidyl cyanurate compounds having at least one group shown in (ii) This aromatic polyamide fiber is characterized in that the aromatic polyamide is crosslinked to improve chemical resistance. The term "polymetaphenylene isophthalamide aromatic polyamide" as used in the present invention generally refers to homo- or copolyamides in which 85 mol% or more of polymer repeating units are metaphenylene isophthalamide. Such a polymetaphenylene isophthalamide aromatic polyamide can be obtained by a solution polymerization method or an interfacial polymerization method using a predetermined aromatic dicarboxylic acid halide and an aromatic diamine. Polymetaphenylene isophthalamide-based aromatic polyamide is obtained by neutralizing the polymerization solution obtained by solution polymerization, and then used as a spinning dope (solution for fiber forming).
Alternatively, the polymer obtained by, for example, a known oligomer polymerization method or interfacial polymerization method may be separated from the polymerization reaction mixture and dissolved in an appropriate solvent to form a spinning dope. Regardless of which spinning dope is used, the spinning dope for the fibers of the present invention contains a solvent of the following group called a polar amide solvent at a concentration of 4 to 30, preferably 5 to 25% by weight of the aromatic polyamide. It is preferable to use Tetramethylurea (TMU), N,N-dimethylacetamide (DMAC), N-methyl-pyrrolidone-2 (NMP), N,N-dimethylformamide (DMF), N-methylformamide and mixed solvents thereof. These solutions may contain a halide of a metal of Group 1 or Group 2 of the periodic table and/or hydrogen halide, if necessary. The above halides include calcium chloride,
Lithium chloride is particularly preferably used. When producing a spinning dope by the redissolution method, it is preferable to grind the polymer sufficiently finely in advance, and it is also preferable to use one with a low degree of crystallinity. In this case, the polymer is sufficiently mixed with the amide solvent at a low temperature of, for example, 0°C or lower, particularly -10°C or lower, and then mixed and dissolved at a high temperature of, for example, 50 to 100°C to obtain a spinning dope. It is preferable to make one. As a method for spinning the fibers of the present invention, a commonly known dry spinning method or wet spinning method is used. The fibers that have been spun and washed are preferably stretched before or after drying. Stretching is from room temperature to 100℃
The stretching may be carried out in water or steam, or hot stretching may be carried out after drying, or both may be carried out sequentially. The respective stretching ratios and hot stretching temperatures vary depending on the type of aromatic polyamide, coagulation and washing conditions, and further vary depending on the desired physical properties, but can be easily determined through a series of experiments. It is expressed using the intrinsic viscosity of 1.V., which is a guideline for the degree of polymerization of aromatic polyamide-based polymers. IV is determined by measuring the viscosity of a solution of a polymer dissolved in concentrated sulfuric acid at 30°C and using the formula below. IV=ln ηr/C C=polymer concentration (polymer g/concentrated sulfuric acid dl) 1.V. of the aromatic polyamide used in the aromatic polyamide fiber of the present invention is 1.0 to 8.0, preferably 1.5
~6.0. In the aromatic polyamide fiber of the present invention, the compound blended into the aromatic polyamide is (a) represented by the following formula (i) or (ii): (However, R ₁ , R ₂ , R ₃ , and R ₄ are hydrogen or alkyl groups.) A derivative of cyanuric acid or isocyanuric acid. That is, a compound represented by the following formula (iii) or (iv) However, in (iii) and (iv), the plurality of G's may be the same or different, and at least two of the G's are groups represented by the above formula (i), and the rest are groups represented by the above formula.
Groups represented by (i) and/or (ii) or 1 in Q
It is the basis of valence. Q is a divalent to tetravalent organic group, Q' is a direct bond or a divalent or higher organic group, r is 0 or 1, preferably p is an integer of 0 to 10, and q is 1 to 3.
is an integer. Specific examples include triallyl cyanurate,
Triallyl isocyanurate is mentioned. (b) General formula A bismaleimide compound represented by Here, R ₅ represents an alkyl group or an aryl group having 1 to 12 carbon atoms. Specific examples of the bismaleimide compound of formula (v) include N,N'-ethylene bismaleimide, N,
N′-m-phenylene bismaleimide, N,
N'-4,4'-diphenylmethane bismaleimide, N,N'-4,4'-diphenyl ether bismaleimide, N,N'-4,4'-diphenylsulfone bismaleimide, N,N' -m-xylylene bismaleimide and N,N'-p-xylylene bismaleimide. (c) Glucidyl cyanurate compound represented by the following formula (vi) or (vii) [However, in (vi) and (vii), a plurality of E's may be the same or different, and at least two of them are groups represented by the following formula (viii), and the rest are (viii) It is a group represented by the formula or a monovalent group in Q. Q is a divalent to tetravalent organic group, Q' is a direct bond or a divalent or higher organic group, r is 0 or 1, preferably 1, p is an integer of 0 to 10, and q is 1 to 3. is an integer. _R1 to _R3 represent hydrogen or an organic group. ] Specific examples include tris(glycidyl) isocyanurate, di(glycidyl)methyl isocyanurate, di(glycidyl)ethyl isocyanurate, ethylene bis(diglycidyl isocyanurate), oxydiethylene bis(diglycidyl isocyanurate), diglycidyl Allyl isocyanurate, tris (glycidyl) cyanurate, di (glycidyl) methyl cyanurate, di (glycidyl) ethyl sialate, ethylene bis (diglycidyl cyanurate), tetramethylene (diglycidyl cyanurate),
Examples include oxydiethylene bis(diglycidyl cyanurate) and di(glycidyl)allyl cyanurate. These compounds are e.g. Zn.Organ.Khim.2
(10)1742 (1965) or J.Am.Chem.Soc.
733003 (1951) or Kunstoffe55641 (1965)
It can be easily synthesized by the method shown in et al. Next, in the present invention, the method of blending the above-mentioned crosslinkable compound into the aromatic polyamide is as follows (i)
This is method (iii). (i) A method in which the compound is blended into a polymer solution in advance and used as a spinning dope for fiber forming, and the compound is blended into the fiber. (ii) A method in which fibers are formed from a polymer solution that does not contain the compound, and the compound is impregnated and blended by a method such as dipping, spraying, or coating in the intermediate or final step of the fiber manufacturing process. (iii) There is a method in which the above methods (i) and (ii) are combined, but method (ii) is preferred when the crosslinkable compound is easily dissolved in the coagulating liquid or washing liquid during the fiber manufacturing process. The appropriate amount is 0.1 to 10% by weight based on the polymer. Aromatic polyamide fibers blended with a predetermined crosslinkable compound can exhibit the effects of the present invention by being treated with heat, ultraviolet rays, or electron beams, or a suitable combination as necessary. When irradiating with ultraviolet rays, there is no particular limitation on the amount of irradiation, but irradiation with a 2kW light source for 30 seconds or more is preferred. Furthermore, although it is possible to use a sensitizer such as benzophenone if necessary, one advantage of the present invention is that in the case of the aromatic polyamide fiber, there is no need for a photosensitizer, and its effect is sufficiently enhanced. There is an advantageous phenomenon in which In the case of electron beam irradiation, there is no particular limitation on the dose, but it is preferably 0.5 Mrad or more. Heat treatment is one effective treatment method that exhibits the effects of the present invention, and heat treatment alone or in combination with ultraviolet irradiation can be considered. When only heat treatment is performed, a radical initiator may be used in combination, if necessary. The heat treatment temperature varies slightly depending on the type of crosslinking agent, the crystallinity of the aromatic polyamide fiber, the degree of polymerization, etc., but is preferably in the range of 110 to 310°C. Ultraviolet rays, electron beams, and heat treatments may be used not only alone, but also in combination, and in some cases, it may be advantageous to use them in combination. In this way, by applying heat, ultraviolet rays, or electron beam treatments, the heat resistance and chemical resistance such as acid resistance can be selectively improved without significantly reducing the mechanical properties of the fibers. This is a major feature of the fiber of the present invention. <Effects of the Invention> Unlike ordinary aromatic polyamide fibers, the aromatic polyamide fiber of the present invention has substantially improved resistance to solvents. For example, when a polymetaphenylene isophthamide polymer fiber containing the crosslinkable compound is treated with an appropriate method such as heat, ultraviolet rays, or electron beam,
It is substantially insoluble in a salt-containing polar solvent that completely dissolves β-type polymetaphenylene isophthalamide,
It is recognized that the solubility is different.
Furthermore, the fiber was found to have an insoluble portion even in concentrated sulfuric acid, which indicates that the fiber of the present invention is a novel aromatic polyamide fiber that has not been previously known. In this way, the aromatic polyamide fiber of the present invention is
Since it has excellent chemical resistance such as heat resistance and acid resistance, it can be used in filters that require heat resistance and chemical resistance. It is also used as a reinforcing fiber in electrically insulating paper-like materials. Furthermore, it is used as spun fabric as spun dyed yarn or dyed yarn, and is also used for heat resistance, flame retardance, flame retardant clothing, curtains, and other interior decoration applications due to its improved physical properties. <Examples> Examples of the present invention will be described below. Comparative Example 1 Polymetaphenylene isophthalamide (I.
V.1.80) 20 parts by weight of N-methylpyrrolidone-280
A spinning stock solution was prepared by dissolving in parts by weight. This spinning stock solution is passed through a spinneret with a hole diameter of 0.08 mm and a number of holes of 100 at a rate of 0.2 per minute.
The sample was coagulated by extrusion into an aqueous solution of inorganic salts mainly composed of calcium chloride at a ratio of cc, and then washed with water at room temperature and then with hot water at 70°C. Further, it was stretched in boiling water to a stretching ratio (DR ₁ ) shown in the table below, dried at 120°C, then stretched on a hot plate at 350°C to a stretching ratio (DR ₂ ) shown in Table 1 below, and wound up.
The strength, elongation, and heat resistance of the obtained fibers are indicated by the heat shrinkage rate at 300℃ (S ₃₀₀ ), acid resistance, and LiCl resistance.
The NMP property was as shown in Table 1. The obtained fibers were heated at 130℃ in the coexistence of paraphenylphenol.
When stained with acid dye for 90 minutes, it was dyed in a deep color. Here, the thermal shrinkage rate at 300° C. is determined by the following equation from the length l after the relaxation heat treatment in air at 300° C. for 30 minutes and the length l ₀ before treatment. S ₃₀₀ = l ₀ - l/l ₀ Acid resistance is determined by soaking 3.0 g of fiber in 200 ml of concentrated sulfuric acid, dissolving it with stirring at the temperature listed in Table 1 for 1 hour, filtering it, washing thoroughly with water, and drying. It is expressed as the weight percent of the fiber insoluble in sulfuric acid, which is calculated from the weight (W) and the original fiber weight (W ₀ ) using the following formula. Acid resistance = sulfuric acid insoluble area (wt%) = W/W ₀ Also, to measure the insoluble area in salt-containing polar amide solvents, soak 0.5 g of fiber in 20 ml of N-methylpyrrolidone-2 solution containing 4.5% lithium chloride. After dissolving at 75℃ for 3 hours with stirring, thoroughly washing with water and drying, perform the same procedure as the sulfuric acid measurement.
It is shown in the table as LiCl-NMP property (%).

[Table] Example 1 Strength, elongation, S ₃₀₀ ,
Acid resistance is shown in Table 2. Further, these fibers are dyed in a deep color as in Comparative Example 4. It can be seen that S ₃₀₀ and acid resistance are improved compared to Comparative Example 1. This is an effect of the present invention due to the addition of a crosslinking agent called triglycidyl isocyanuric acid and the crosslinking heat treatment by hot stretching at 350°C.

[Table] Comparative Example 2 After obtaining fibers in exactly the same manner as in Comparative Example 1, the fibers were irradiated with ultraviolet light for 5 minutes at a distance of about 15 cm from a 2KW high-pressure mercury lamp. Strength, elongation, S ₃₀₀ , acid resistance and LiCl resistance of the fibers obtained after irradiation
The NMP properties are almost the same as those shown in Table 1 of Comparative Example 1, and when irradiated with light without adding a crosslinking agent,
It was found that S ₃₀₀ , acid resistance, and LiCl-NMP resistance did not improve. Example 2 Fibers were obtained in exactly the same manner as in Comparative Example 1, except that in Comparative Example 2, 1 part by weight of triallyl isocyanurate was added to the spinning dope to prepare the spinning dope. Its strength, elongation, S ₃₀₀ and acid resistance are shown in Table 3. Furthermore, the fibers obtained earlier were irradiated with ultraviolet light for 5 minutes from a 2KW high-pressure mercury lamp at a distance of approximately 15cm. The strength, elongation, and elongation of the fibers obtained after irradiation treatment
S ₃₀₀ and acid resistance are shown in Table 4. The results in Table 4 show that when triallylisocyanurate is blended as a crosslinking agent, heat treatment at 35°C improves heat resistance (S ₃₀₀ ) and LiCl-NMP resistance, but the improvement in acid resistance is insufficient. It can be seen that acid resistance is improved by UV irradiation. Further, these obtained fibers are dyed in a deep color as in Comparative Example 1.

【table】

[Table] Example 3 Fibers were prepared in the same manner as in Comparative Example 1, except that 1 part by weight of triallyl cyanurate, triglycidyl cyanurate, and bismaleimide were each added when preparing the spinning dope. I got it. The results are shown in Table-5. Furthermore, these fibers were irradiated with light in exactly the same manner as in Comparative Example 2, and the results are shown in Table 6.

【table】

[Table] Comparative Example 3 The fibers obtained in Comparative Example 1 without a crosslinking agent (DR ₁ × DR ₂ = 2.30 × 1.37 in Table 1) were treated with Hypertron 30EBCA-300A type electron beam irradiation equipment.
A dose of 5 Mrad was irradiated. The strength, elongation, S ₃₀₀ , acid resistance, and LiCl-NMP resistance of the fibers thus obtained were 4.1 g/d, 68%, 29%, and 9% (25
℃), 5% (60℃), and 30%. Example 4 Instead of the ultraviolet irradiation in Example 2, fibers of DR ₁ ×DR ₂ =2.30 × 1.37 in Table 3 were used and a dose of 5 Mrad was irradiated with a Hypertron 30EBCA-300A type electron beam irradiation device. The strength, elongation, and
S ₃₀₀ , acid resistance, LiCl-NMP resistance are each 3.9
g/d, 49%, 15%, 67% (25℃), 38% (60
℃), 89%. From this result, compared to Comparative Example 3 and Table 3 of Example 2, electron beam irradiation slightly improves heat resistance (S ₃₀₀ ), acid resistance, and LiCl-NMP resistance even when no crosslinking agent is added. It can be seen that the effect is even greater when a crosslinking agent is added. Comparative Example 4 Comparative Example 1 except for the conditions of 21.5 parts by weight of polymetaphenylene isophthalamide, 278.5 parts by weight of N-methylpyrrolidone, and DR ₁ × DR ₂ listed in Table 7.
Fibers were obtained under exactly the same conditions. The strength, elongation, S ₃₀₀ , acid resistance, and resistance of the obtained fibers were
The LiCl-NMP property was as shown in Table 7.

[Table] Example 5 Fibers were obtained in the same manner as in Comparative Example 4, except that 0.65 parts by weight of triglycidyl isocyanurate was added to prepare the spinning dope in Comparative Example 4. The fibers obtained were as shown in Table 8.

[Table] Example 6 Using the same spinning stock solution as used in Comparative Example 4, triglycidyl cyanurate was drawn after boiling water stretching.
The fibers were immersed in a saturated aqueous solution at 70°C. Then, it was dried, hot-stretched, and wound onto a bobbin. Other conditions were exactly the same as in Comparative Example 4. The obtained fibers were as shown in Table 9.

【table】

Claims (1)

[Scope of Claims] 1. A fiber mainly composed of a polymetaphenylene isophthalamide-based aromatic polyamide, wherein the aromatic polyamide has at least one group shown in (i) or (ii) below. The aromatic polyamide is cross-linked by treatment with heat, ultraviolet rays, or electron beams in a state containing at least one of cyanuric acid or isocyanuric acid derivatives, [] bismaleimide compounds, or [] glycidyl isocyanurate compounds. An aromatic polyamide fiber that is characterized by having improved chemical resistance. (However, R ₁ , R ₂ , R ₃ , R ₄ are hydrogen or alkyl groups)