JPS6356804B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a material that can survive fluids containing acidic substances at high temperatures for long periods of time. Traditionally, materials such as glass fiber and asbestos have been used as materials for fluids that are at high temperatures (approximately 150°C or higher) and contain acidic substances (e.g., gases such as SO ₂ , SO ₃ , H ₂ SO ₄ , HCl, etc.). Inorganic fibers or organic heat-resistant synthetic fibers such as aromatic polyamide fibers have been used. However, the former has excellent heat resistance but poor bending durability, and the fabric made of this has the disadvantage of being severely damaged when dust is removed and has a short service life. However, it had the disadvantage of being hydrolyzed by acid, resulting in a decrease in strength. In order to solve these problems, it has been proposed to coat the surface of heat-resistant synthetic fibers with a hydrolysis-resistant resin, such as a fluorocarbon resin or a silicone resin. The present inventors have developed an aromatic polyamide resin composition in which a fluorinated alkyl (meth)acrylate resin or a resin having a fluorine bond in the main chain is blended with an N-methylol resin. We first proposed an acid-resistant cloth with greatly improved acid resistance by coating the fibers (Japanese Patent Application Laid-Open No. 1983-1999).
-124414; hereinafter referred to as prior art 1). Prior art 1 is an acid-resistant material made by coating the fiber surface of a sheet-like structure made of aromatic polyamide fibers with a resin mixture made of N-methylol resin and fluorine-based resin, and its acid resistance is good. can be
It can be used as a dust-filtering material in an acidic gas atmosphere with SO ₂ of 100 ppm or less. However, since aromatic polyamide fibers are used, its acid resistance is not satisfactory for use as a material for filtering dust with a high concentration of acidic gases. There has been a demand for the development of In contrast, as a result of detailed studies on the characteristics of aromatic polyetheramide fibers, the present invention found that aromatic polyetheramide fibers have superior acid resistance (alkali resistance), chemical resistance, bending fatigue resistance, etc. The inventors have discovered that this material is superior to fibers, and therefore, when used as an acid-resistant material, can provide an acid-resistant material that is even better than aromatic polyamide fibers, leading to the present invention. In other words, the present inventors used a resin compound containing an N-methylol resin and a fluorinated alkyl (meth)acrylate resin known as a fluorine-based fiber treatment agent or a resin having a fluorine bond in the main chain as an aromatic compound. The present invention was achieved by discovering that a material with extremely good acid resistance can be obtained by coating polyetheramide fibers. The present invention is an acid-resistant material formed by coating the fiber surface of a sheet-like structure made of aromatic polyetheramide fibers with a resin blend made of an N-methylol resin and a fluorine resin. The aromatic polyetheramide fiber referred to in the present invention consists of the following repeating units (1) to (4), [In the formula, Ar ₁ , Ar ₂ , and Ar ₃ may be the same or different, and are aromatic carbocyclic residues in which the bonding chains extend coaxially or in parallel axes; represents aromatic heterocyclic residues and combinations thereof that must be bonded accordingly. R ₁ to _{R 5} may be the same or different and represent an alkyl group having 5 or less carbon atoms and a hydrogen atom. Ar ₄ and Ar ₅ may be the same or different and are selected from paraphenylene group and metaphenylene group. The relationship between the number of moles of repeating units is essentially (1) + (4) =
(2) and (1) + (2) + (3) + (4) = 100 mol%, (3) = 0 to 90 mol%, (4) = 50 to 5 mol%, preferably is a fiber made of a polymer in which (4)=30 to 10 mol%. Aromatic carbocyclic residues in which bond chains extend coaxially include, for example, 1,4-phenylene, 1,4-
An aromatic carbocyclic residue with a bond chain extending in the direction of a parallel axis, such as naphthylene, is, for example, 1,
It means 5-naphthylene, 2,6-naphthylene, etc. The aromatic residue is -N=N-, -N=CH-,
They may be bonded to each other through a group selected from the group consisting of -CH=CH- and -C≡C-. for example,

【formula】

【formula】

【formula】

[Formula] etc. Examples of the alkyl group having 5 or less carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, etc., and a methyl group is preferable. Ar ₄ and Ar ₅ in formula (4) may be the same or different and are selected from a paraphenylene group and a metaphenylene group. A substituent may be bonded to the carbon atom of the above aromatic carbocyclic residue and aromatic heterocyclic residue. Such substituents include halogen groups (e.g., chlorine, bromine, fluorine), lower alkyl groups (e.g., methyl, ethyl, isopropyl, n-propyl groups), lower alkoxy groups (e.g., methoxy, ethoxy groups), cyano groups, Examples include an acetyl group and a nitro group, with chlorine and methyl groups being preferred. ] In the present invention, the N-methylol resins include melamine resins (resins produced by addition condensation of melamine and formalin), urea resins (resins produced by addition condensation of urea and/or urea and formalin, and urea-melamine-formalin resins). ), an initial condensation polymerization composition in which N-methylol groups mainly contribute to the condensation crosslinking reaction, such as acrylamide resin (acrylamide alone or a copolymer of a vinyl monomer mixture containing acrylamide as a main component), or the like. Refers to products whose main component is polycondensation products. In use, these resins can be used alone, or mixtures or reactants thereof can be used. The fluorine-based resin referred to in the present invention is a polyfluoroalkyl group-containing water and oil repellent agent known as a water and oil repellent having the general formula _CH2 =C( ^R1 )COO(R)mRf (where Rf in the formula has 3 to 3 carbon atoms). 20 linear or branched perfluoroalkyl groups, R ¹ is a hydrogen atom or a methyl group, R
is a linear or branched divalent alkylene group having 1 to 10 carbon atoms, m is 0 or 0)
A polymer of acrylate or methacrylate represented by or a compound that can be polymerized with these without containing a polyfluoroalkyl group, such as (meth)acrylic acid and its alkyl ester, (meth)acrylamide and its N-methylol compound, vinyl acetate, etc. or a copolymer with two or more types, a polymer or copolymer containing a fluorine bond in the main chain known as a fluororesin or fluororubber, such as tetrafluoroethylene, tetrafluoroethylene-propylene copolymer, vinyl fluoride - Refers to hexafluoropropylene copolymer, etc. In use, these resins can be used alone or in combination. The material of the present invention is a sheet-like structure such as a woven or knitted fabric or a non-woven fabric made of the above-mentioned aromatic polyetheramide fiber, and the fiber surface thereof is coated with a resin blend of an N-methylol resin and a fluorine resin. . N
- When the fiber surface is coated with methylol resin, the resin coats the fiber surface very well, and the resin itself has relatively good acid resistance against acidic substances, so materials with good acid resistance are used. I can get it. On the other hand, fluorine-based resins, i.e., fluorinated alkyl (meth)acrylate resins known as fluorine-based resin treatment agents, or resins with fluorine bonds in their main chains are resins with good acid resistance. When a material is impregnated with an aqueous dispersion obtained by emulsification and dried to coat the fiber surface, the resin does not cover the fiber surface well and does not form a uniform film, so the resin itself has poor acid resistance. At best, the acid resistance of the resin-coated material is not good. The present inventors have discovered that a resin compound in which a fluorine-based resin is blended with an N-methylol resin has extremely good coating properties on the fiber surface, and the acid resistance of the blended resin itself is also good. It was discovered that the treated material has extremely good acid resistance, and the present invention was developed based on this finding. Therefore, the acid resistance of the material depends on the blending ratio of the N-methylol resin and the fluorine resin, and the preferred resin blending ratio is 98:2 to 70:30 by weight. When the blending ratio of the fluorine-based resin is 2% or less, the coating properties of the resin blend on the fiber surface are good, but
The resin itself has little effect on improving acid resistance, and on the contrary,
% or more, the acid resistance of the resin itself improves, but the coverage of the fiber surface gradually decreases, and the effect of improving acid resistance also decreases. As a method for coating the fiber surface of a sheet-like structure made of aromatic polyetheramide fibers with such a resin compound, the fiber surface may be coated with resin in advance and used for knitting or non-woven fabric. When the N-methylol resin is attached, the fibers generally harden, resulting in poor processing efficiency and reduced productivity, so it is more advantageous to attach the N-methylol resin after forming a sheet-like product. The resin aqueous solution preferably contains a crosslinking agent, a catalyst, and the like. Such crosslinking agents and catalysts include catalysts that promote the condensation reaction of N-methylol resins, such as free acids, alkalis, ammonium salts such as diammonium phosphate, rhodanammonium, and ammonium chloride, and 2-methyl-
Organic and inorganic acid salts of aliphatic amino alcohols such as 2-aminopropanol hydrochloride, morpholine hydrochloride, 2-aminobutanol phosphate, triethanolamine hydrochloride, metals such as magnesium chloride, zinc nitrate, zinc chloride, etc. An example is salt. The amount of the coating cannot be determined uniformly because it depends on the type of resin used, the type and thickness of the fibers, but it is 4 to 20% by weight, preferably 5 to 15% by weight, based on the weight of the fibers. If it is less than 4%, the effect of improving acid resistance is poor, and if it exceeds 20%, the effect of improving acid resistance is saturated, and conversely, the material becomes hard and clogs occur. The resin treatment is carried out by mixing a predetermined amount of an N-methylol resin, a fluorine resin, a crosslinking agent, and water and attaching the mixture to the fiber surface of a sheet-like structure made of aromatic polyetheramide fibers. When mixing resins, N-methylol resins are usually obtained in the form of an aqueous solution, and fluorine-based resins are obtained in the form of an emulsion, but depending on the type of emulsifier, the emulsion may be destroyed during mixing. Emulsifier selection should be avoided. Examples of resin treatment methods include pad method, dipping method,
Examples include coating method and spray method. After applying a liquid resin to the fiber surface with a uniform thickness by these methods, the fiber (fabric) is dried at a temperature of about 80 to 130°C. At that time, if a coarse fabric is treated with resin, you may use any dryer such as a shoot loop dryer, non-touch dryer, or tenter. However, if a particularly dense fabric is treated with resin, For the purpose of preventing clogging caused by the fabric, it is preferable to dry the fabric using suction power such as a suction drum dryer, or to remove clogging from the fabric using a vacuum dehydrator before drying and then drying with an arbitrary dryer. .
After drying, it is desirable to perform curing at approximately 130 to 170°C for several minutes. As mentioned above, the material of the present invention has acid resistance by selecting aromatic polyetheramide fiber as a highly heat resistant fiber and coating the surface with a resin mixture containing N-methylol resin and fluorine resin. Made of a material with excellent heat resistance, bending abrasion resistance, and dust-collecting properties, it can efficiently handle high-temperature and acidic fluids (especially gases) directly without diluting or lowering the temperature beforehand. Even if clogging occurs, it can be regenerated by "blowing it off", so it can be used for a long time. Therefore, it can be used for example in boilers (for heavy oil and coal combustion), blast furnaces (blast furnaces), and converters (combustion furnaces). It is possible to efficiently filter out acidic gases or acid-containing factory wastewater from open hearths, roasting furnaces, sintering furnaces, drying furnaces, cupolas, or waste incinerators. Next, the present invention and its effects will be explained with reference to Examples. In addition, "strength retention rate" indicating heat resistance and acid resistance in the example is expressed as the ratio of tensile strength of the fabric before and after attaching concentrated sulfuric acid to a 5 cm wide cloth and heating it, and "% strength retention rate" other than "strength retention rate" ” are all “% by weight”. Examples 1 to 5, Comparative Example 1 The aromatic polyetheramide fiber was a polymer consisting of 25 mol% paraphenylene diamine, 50 mol% terephthalic acid chloride, and 25 mol% 3,4'-diamino-diphenyl ether. A fabric (surge) with a basis weight of 250 g/m ² made of filament fibers obtained by wet-spinning is coated with resin solutions having the five compositions shown in Table 1 below using the pad method. ) 120℃ after adhesion
Drying was carried out for 5 minutes at 150°C, followed by curing for 3 minutes at 150°C. The resin liquid was prepared by weighing a predetermined amount of the components shown in each example, mixing them, and stirring until the mixture was homogeneous. The five types of resin-treated fabrics were immersed in a 20% aqueous sulfuric acid solution and heated at 150°C for 1 hour, after which the strength retention of the fabrics was measured. Let the result be F-1. Then, the same process was repeated three times to measure the strength retention rate of the fabric, and the result was designated as F-4. The results obtained are shown in Table 1. For comparison, the same fabric used in the above example was treated with sulfuric acid in the same manner as above without being treated with resin, and the strength retention rate of the fabric was determined as Comparative Example 1. Ta. Comparative Example 2 was evaluated in the same manner as Comparative Example 1, without resin treatment, except that polymetaphenylene isophthalamide fibers were used. The results obtained are shown in Table 1.

【table】

[Table] Examples 6 to 9, Comparative Example 3 The fabrics made of aromatic polyetheramide fibers used in Examples 1 to 5 were added with the 4 materials shown in Table 2 below.
A resin solution having the same composition as described above was deposited at 12% (as resin) on each of the fabrics by a padding method, and then dried at 100°C for 3 minutes, and then cured at 150°C for 3 minutes. The strength retention rates of the two types of resin-treated fabrics after acid treatment were measured in the same manner as in Example 1, and the results are shown in Table 2. Examples 6 to 9 except that for comparison, a fabric made of polymetaphenylene isophthalamide fiber was treated with a resin liquid having the composition shown in Example 7.
After treatment in the same manner as above, the strength retention rate was measured. The results are shown in Comparative Example 3.

【table】

[Table] Examples 10 to 12, Comparative Examples 4 to 6 5 sheets of 20 count double yarn obtained by spinning 2 denier, 51 mm length aromatic polyetheramide fibers, satin texture, number of threads 79 threads/inch x 52 book/inch/(vertical)
A resin solution having the composition shown in Table 3 below was applied to a fabric (weaving area: 323 g/m ² ) that was woven into a × (horizontal) fabric and heat-set at 190°C using a padding method to adhere 7% (as resin) to each fabric. 100℃ after tightening
The film was dried at 170° C. for 3 minutes, and then cured at 170° C. for 3 minutes. The strength retention rate of this resin-treated fabric after treatment with sulfuric acid was measured in the same manner as in Example 1, and the results are shown in Table 3. For comparison, the same fabric as that used in the above example was used as it was, or a resin liquid having a composition ratio of N-methylol resin and fluorine resin outside the scope of the claims of the present invention was used. The strength retention rate of the treated fabric after sulfuric acid treatment was shown. From this table, it is clear that the blending ratio of N-methylol resin and fluorine resin greatly influences the acid resistance of the material.

[Table] Examples 13 to 16, Comparative Examples 7 to 9 Number of 20 count twin yarns obtained by spinning 2 denier, 51 mm long aromatic polyetheramide fibers
A plain weave fabric of 32 pieces/inch x 32 pieces/inch/(vertical) x (horizontal) is woven, and this woven fabric is used as a base fabric, and aromatic polyetheramide fibers of 2 denier and 71 mm length are woven using a regular batting machine. The web created through a carding machine was needle punched to obtain a nonwoven fabric with a basis weight of 450 g/m ² . Resin liquids having the composition shown in Table 4 below were applied to this nonwoven fabric at varying concentrations, and then dried at 120°C for 10 minutes, and then cured at 165°C for 5 minutes. The strength retention rate of this resin-treated nonwoven fabric after treatment with sulfuric acid was measured in the same manner as in Example 1, and the results are shown in Table 4. For comparison, the strength retention rate after treatment with sulfuric acid of a nonwoven fabric whose resin adhesion amount is outside the scope of the claims of the present invention is shown (Table 5). As a result, if the amount of resin attached is too small, the acid resistance will not be satisfactory, and if the amount of resin attached is too large, the acid resistance will reach saturation, and on the other hand, the material will become too hard and clog, which is not preferable.

【table】

【table】

Claims (1)

[Scope of Claims] 1. The fiber surface of a sheet-like structure made of aromatic polyetheramide fibers has a blending ratio (weight ratio) of N-methylol resin and fluorine resin of 98/2 to 98/2.
Acid-resistant material coated with a 70/30 resin compound. 2. The acid-resistant material according to claim 1, wherein the fluorine-based resin is a fluorinated alkyl (meth)acrylate-based resin. 3. Acid resistance according to claims 1 and 2, which is obtained by coating the amount of aromatic polyetheramide fiber with 4 to 20% by weight of a resin blend of N-methylol resin and fluorine resin. Material. 4. The acid-resistant material according to any one of claims 1 to 3, wherein the N-methylol resin is a mixture of a urea resin, a melamine resin, and/or an acrylamide resin. 5. The acid-resistant material according to any one of claims 1 to 4, wherein the aromatic polyetheramide fiber comprises the following repeating units (1) to (4). [In the formula, Ar ₁ , Ar ₂ , and Ar ₃ may be the same or different, and are aromatic carbocyclic residues in which the bonding chains extend coaxially or in parallel axes; Therefore, it represents aromatic heterocyclic residues that must be bonded and combinations thereof. R ₁ to _{R 5} may be the same or different and represent an alkyl group having 5 or less carbon atoms and a hydrogen atom. Ar ₄ and Ar ₅ may be the same or different and are selected from paraphenylene group and metaphenylene group. The relationship between the number of moles of repeating units is essentially (1) + (4) =
(2), and when (1) + (2) + (3) + (4) = 100 mol%, (3) = 0 to 90 mol%, (2) = 50 to 5 mol% . ] 6 Ar ₁ of repeating unit (1) is paraphenylene and R ₁ ,
Both R ₂ are hydrogen atoms, and Ar ₂ of repeating unit (2)
The acid-resistant material according to claim 5, wherein is paraphenylene, Ar ₄ of the repeating unit (3) is paraphenylene, and R ₃ is a hydrogen atom. 7 R ₄ and R ₅ of the repeating unit (4) are hydrogen atoms,
The acid-resistant material according to any one of claims 5 to 6, wherein Ar ₄ is paraphenylene, and Ar ₅ is paraphenylene or metaphenylene.