JP6006625B2 - Phenol fiber nonwoven fabric and filter using the nonwoven fabric - Google Patents

Description

  The present invention relates to a phenol fiber nonwoven fabric and a filter using the nonwoven fabric.

  Nonwoven fabrics made of phenolic fibers are excellent in heat resistance, flame retardancy and chemical resistance, and have been used for many years in fields where these characteristics are required.

  In recent years, the nonwoven fabric has been required to reduce pressure loss from the viewpoint of high performance when used for filter applications, for example. In order to reduce this pressure loss, there has been a demand for phenolic fibers having a single fiber fineness higher than that of the prior art, that is, having a large fiber diameter.

  However, there is a problem that mechanical strength (particularly breaking strength and breaking elongation) required for making a nonwoven fabric is insufficient when the fineness of phenolic fibers is increased using a conventional production method. . This is due to the following reason.

  That is, the phenolic fiber is generally produced by melt-spinning a thermoplastic novolac-type phenolic resin, and then reacting with an aldehyde under an acidic catalyst to perform three-dimensional crosslinking, thereby making it thermally infusible. ing.

  In addition to being completely amorphous, the novolak type phenol resin has a low degree of polymerization and a high temperature dependency of viscosity. Therefore, a yarn obtained by melt spinning a novolac type phenolic resin rapidly solidifies as the ambient temperature decreases, but has a very brittle property. In particular, the yarn before the crosslinking reaction is fragile. Further, the fiber obtained by curing (three-dimensional cross-linking) the yarn with aldehydes to be heat infusible loses flexibility and becomes extremely brittle. And the fall of the flexibility by hardening becomes more remarkable with the increase in the fineness of a phenol-type fiber.

For this reason, as a nonwoven fabric using phenolic fibers having a high fineness, there has been a material whose mechanical strength is increased by increasing the bulk density to 110 kg / m ³ or more. There was a problem that the loss was high (see, for example, Patent Document 1).

JP 2002-161439 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a phenol fiber nonwoven fabric having high mechanical strength in spite of low pressure loss.

The phenol-based fiber nonwoven fabric of the present invention that has solved the above-mentioned problems is obtained by processing a phenol-based fiber having a single fiber fineness of 7 dtex to 22 dtex, and has a basis weight of 400 g / m ^{2 to} 2000 g / m ² and a tensile strength of 30 N / It is characterized by having a density of cm ² or more, a bulk density of 100 kg / m ³ or less, and a ventilation pressure loss coefficient per unit thickness of 0.3 mmAq · s / cm ² or less.

  In the present invention, it is a preferred embodiment that the phenol fiber is produced using a mixture in which a phenol resin is mixed with a fatty acid amide and / or a phosphate ester.

  The present invention also includes a filter produced using the above-mentioned phenol-based fiber nonwoven fabric.

  In addition, the filter in the present invention is composed of a nonwoven fabric, a filter that captures a solid or liquid mist floating in a gas, a heat-resistant filter that collects high-temperature dust discharged from a coal boiler or a garbage incinerator, etc. Is mentioned.

  The phenol fiber nonwoven fabric of the present invention has a high single fiber fineness of the phenol fiber constituting the nonwoven fabric and is excellent in tensile properties, so that a nonwoven fabric excellent in pressure loss and mechanical strength could be obtained. Moreover, since the nonwoven fabric of this invention consists of a phenol-type fiber, heat resistance, a flame retardance, and chemical resistance are favorable.

The phenol fiber nonwoven fabric of the present invention is obtained by processing a phenol fiber having a single fiber fineness of 7 dtex to 22 dtex, and has a basis weight of 400 g / m ^{2 to} 2000 g / m ² , a tensile strength of 30 N / cm ² or more, and a bulk density of 100 kg / m ³ or less, it is equal to or less than passing pressure loss coefficient 0.3mmAq · s / cm ² per unit thickness. Hereinafter, the phenol fiber nonwoven fabric of the present invention will be described in detail.

(Single fiber fineness)
The single fiber fineness (hereinafter sometimes simply referred to as “fineness”) of the phenolic fiber used in the present invention is 7 dtex or more (preferably 8 dtex or more). By using a phenol-based fiber having a fineness of 7 dtex or more, a nonwoven fabric (filter) with sufficiently reduced pressure loss can be obtained. The upper limit of the fineness is 22 dtex (preferably 17 dtex). It is sometimes difficult to process a nonwoven fabric with a phenol fiber having a fineness exceeding 22 dtex.

(Weight)
The nonwoven fabric of the present invention has a basis weight of 400 g / m ² or more (preferably 450 g / m ² or more, more preferably 500 g / m ² or more). By setting the basis weight to 400 g / m ² or more, a nonwoven fabric having a tensile strength of 30 N / cm ² or more can be obtained. The upper limit of the basis weight is 2000 g / m ² (preferably 1800 g / m ² , more preferably 1600 g / m ² ). A nonwoven fabric having a basis weight exceeding 2000 g / m ² may be difficult to produce, or even if the nonwoven fabric can be produced, the effect of improving the tensile strength may reach its peak and may lack flexibility.

(Tensile strength)
Non-woven fabric of the present invention, tensile strength 30 N / cm ² or more (preferably 35N / cm ² or more, more preferably 40N / cm ² or more). This is because when the tensile strength is low, sufficient strength cannot be obtained and handling is inferior. The upper limit of the tensile strength is not particularly limited, but it is difficult to produce a nonwoven fabric having a tensile strength exceeding 60 N / cm ² using phenolic fibers having a fineness of 7 dtex to 22 dtex.

Since the nonwoven fabric of this invention is comprised by the large diameter phenolic fiber which has fixed elongation, the nonwoven fabric of this invention has desired tensile strength. Therefore, the nonwoven fabric can exhibit a desired mechanical strength without increasing the bulk density to a high level as conventionally known (for example, 110 kg / m ³ or more disclosed in Patent Document 1). In the present invention, the bulk density of the phenol fiber nonwoven fabric is specifically 100 kg / m ³ or less (preferably 95 kg / m ³ or less, more preferably 90 kg / m ³ or less). When the bulk density exceeds 100 kg / m ³ , the fibers constituting the nonwoven fabric are too dense, and the pressure loss of the nonwoven fabric increases, which is not preferable. The lower limit is not particularly defined but is preferably 70 kg / m ³ or more.

(Nonwoven fabric pressure loss)
Since the nonwoven fabric of the present invention uses high-definition phenolic fibers, the aeration pressure loss coefficient per unit thickness can be 0.3 mmAq · s / cm ² or less. By using the nonwoven fabric, a filter with low pressure loss can be produced. The pressure loss coefficient per unit thickness of the nonwoven fabric of the present invention is preferably 0.25 mmAq · s / cm ² or less. When the pressure loss coefficient per unit thickness exceeds 0.3 mmAq · s / cm ² , the resistance during gas passage is high, and the power loss of the ventilation blower may increase.

(Phenol fiber nonwoven fabric manufacturing method)
The nonwoven fabric of the present invention can be produced by processing a phenol fiber having a fineness of 7 to 22 dtex as a raw yarn. Hereinafter, the manufacturing method of the nonwoven fabric of this invention is demonstrated in detail.

[Phenol fiber]
The phenol fiber used in the present invention is obtained by spinning a mixture in which a phenol resin is mixed with a fatty acid amide and / or a phosphate ester (hereinafter, these may be simply referred to as “compound”). Phenol fibers that can be used are preferably used. By adding the said compound to a phenol resin, since a phenol type fiber can be finished softly, it becomes possible to raise the elongation of a phenol type fiber. In addition, when a non-woven fabric is formed using phenolic fibers to which the above-mentioned blend is added, the entanglement of the fibers can be improved, so compared to a non-woven fabric made from phenol-based fibers made without adding a blend. The desired tensile strength can be imparted to the nonwoven fabric. Thereby, desired mechanical strength can be provided to a nonwoven fabric.

<Phenolic resin>
As the phenol resin, a novolac type phenol resin obtained by reacting phenols and aldehydes in the presence of an acidic catalyst, or a resol type phenol obtained by reacting phenols and aldehydes in the presence of a basic catalyst Examples thereof include resins, various modified phenolic resins, and mixtures thereof.

  The phenols are not particularly limited as long as they can be reacted with aldehydes in the presence of an acidic or basic catalyst to obtain each phenol resin. Phenol, o-cresol, m-cresol, p-cresol, 2, 3 -Xylenol, 3,5-xylenol, m-ethylphenol, m-propylphenol, m-butylphenol, p-butylphenol, o-butylphenol, resorcinol, hydroquinone, catechol, 3-methoxyphenol, 4-methoxyphenol, 3-methyl Catechol, 4-methylcatechol, methylhydroquinone, 2-methylresorcinol, 2,3-dimethylhydroquinone, 2,5-dimethylresorcinol, 2-ethoxyphenol, 4-ethoxyphenol, 4-ethylresorcinol, 3-e Xyl-4-methoxyphenol, 2-propenylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 3,4,5-trimethylphenol, 2-isopropoxyphenol, 4-propoxyphenol, 2-allyl Phenol, 3,4,5-trimethoxyphenol, 4-isopropyl-3-methylphenol, pyrogallol, phloroglucinol, 1,2,4-benzenetriol, 5-isopropyl-3-methylphenol, 4-butoxyphenol, 4-t-butylcatechol, t-butylhydroquinone, 4-t-pentylphenol, 2-t-butyl-5-methylphenol, 2-phenylphenol, 3-phenylphenol, 4-phenylphenol, 3-phenoxyv Nord, 4-phenoxyphenol, 4-hexyloxyphenol, 4-hexanoylresorcinol, 3,5-diisopropylcatechol, 4-hexylresorcinol, 4-heptyloxyphenol, 3,5-di-t-butylphenol, 3,5 -Di-t-butylcatechol, 2,5-di-t-butylhydroquinone, di-sec-butylphenol, 4-cumylphenol, nonylphenol, 2-cyclopentylphenol, 4-cyclopentylphenol, bisphenol A, bisphenol F, etc. Can be mentioned.

  Among them, phenol, o-cresol, m-cresol, p-cresol, bisphenol A, 2,3-xylenol, 3,5-xylenol, m-butylphenol, p-butylphenol, o-butylphenol, 4-phenylphenol, resorcinol Are preferred, with phenol being most preferred. The said phenols may be used individually by 1 type, and may use 2 or more types together.

  Examples of the aldehydes include formaldehyde, trioxane, furfural, paraformaldehyde, benzaldehyde, methyl hemiformal, ethyl hemiformal, propyl hemiformal, salicylaldehyde, butyl hemiformal, phenyl hemiformal, acetaldehyde, propylaldehyde, phenylacetaldehyde, α- Phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p -Ethylbenzaldehyde, pn-butylbenzaldehyde, etc. are mentioned.

  Of these, formaldehyde, paraformaldehyde, furfural, benzaldehyde, and salicylaldehyde are preferable, and formaldehyde and paraformaldehyde are particularly preferable. The aldehydes may be used alone or in combination of two or more.

  Examples of the acidic catalyst include hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, succinic acid, butyric acid, lactic acid, benzenesulfonic acid, p-toluenesulfonic acid, boric acid, and salts with metals such as zinc chloride or zinc acetate. It is done. The said acidic catalyst may be used individually by 1 type, and may use 2 or more types together.

  Examples of the basic catalyst include alkali metal hydroxides such as sodium hydroxide and lithium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide; ammonium hydroxide; diethylamine, triethylamine, Examples include amines such as ethanolamine, ethylenediamine, and hexamethylenetetramine. The said basic catalyst may be used individually by 1 type, and may use 2 or more types together.

  Examples of the various modified phenol resins include those obtained by modifying a novolak-type or resol-type phenol resin by known techniques such as boron modification, silicon modification, heavy metal modification, nitrogen modification, sulfur modification, oil modification, rosin modification and the like.

  In the present invention, it is preferable to use a novolac type phenol resin or a resol type phenol resin. A phenol resin may be used individually by 1 type, and may use 2 or more types together.

<Formulation>
The fatty acid amides used as a blend in the present invention means a non-polymer having a structure in which one or more hydrogen atoms bonded to the nitrogen atom of ammonia or amine are substituted with an acyl group. A primary amide in which two atoms are bonded, a secondary amide in which one hydrogen atom is bonded to the nitrogen atom, a tertiary amide in which no hydrogen atom is bonded to the nitrogen atom, a lactam, and one molecule Includes those having two or more amine nitrogen atoms. Therefore, the “fatty acid amides” in the present invention are different from polymers such as so-called aliphatic polyamides typified by nylon-6 and nylon-6,6. “Fatty acid amides” are also referred to as fatty acid amides.

Examples of the primary amide include compounds represented by the general formula “R ¹ C (═O) NH ₂ ”.
In the above formula, R ¹ is a hydrocarbon group which may have a substituent. Here, “may have a substituent” means that a part or all of the hydrogen atoms of the hydrocarbon group may be substituted with a substituent. The hydrocarbon group for R ¹ may be saturated or unsaturated, and may be linear or branched, and the carbon number thereof is preferably 5 to 31, and more preferably 11 to 23. However, the carbon number of the hydrocarbon group of R ¹ does not include the carbon number in the substituent described later. Examples of the substituent that the hydrocarbon group may have include a hydroxy group and a hydroxyalkyl group. The hydroxyalkyl group preferably has 1 to 11 carbon atoms.

  Specific examples of primary amides include caproic acid amide, caprylic acid amide, pelargonic acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, arachidic acid amide, behenic acid amide, lignoceric acid amide, etc. Saturated fatty acid monoamides such as oleic acid amide, erucic acid amide, and ricinoleic acid amide.

Examples of secondary amides include compounds represented by the general formula “R ¹ C (═O) NHR ² ”.
In the above formula, R ¹ is the same as R ¹ in the description of the primary amide.
In the formula, R ² is a hydrocarbon group which may have a substituent, or —C (═O) R ³ . The hydrocarbon group for R ² may be saturated or unsaturated, and may be linear or branched, and the carbon number thereof is preferably 1 to 23, and more preferably 1 to 17. Examples of the substituent that the hydrocarbon group may have include a hydroxy group.
R ³ may be the same as R ¹ in the description of the primary amide, and R ¹ and R ³ may be the same as or different from each other. A compound in which R ² is —C (═O) R ³ is also referred to as an imide.

  Specific examples of secondary amides include substituted amides such as stearyl stearic acid amide, oleyl oleic acid amide, stearyl oleic acid amide, oleyl stearic acid amide, stearyl erucic acid amide, oleyl palmitic acid amide; methylol stearic acid amide, methylol And methylolamide such as behenic acid amide.

Examples of the tertiary amide include compounds represented by the general formula “R ¹ C (═O) NR ⁴ R ⁵ ”.
In the above formula, R ¹ is the same as R ¹ in the description of the primary amide.
In the formula R ^4, R ⁵ are each like can be mentioned as R ² in the description of the secondary amide, may be different from one another identical R ⁴ and R ^5.

  Specific examples of the tertiary amide include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide and the like.

  Among the lactams, preferred are those having 3 to 12 carbon atoms. Specifically, β-propiolactam, γ-butyrolactam (2-pyrrolidone), δ-valerolactam (2-piperidone), ε-caprolactam, undecaractam, dodecaractam (lauro / laurylactam) and the like can be mentioned. It is done.

Examples of compounds having two or more amine nitrogen atoms in one molecule include compounds represented by the general formula “R ¹¹ C (═O) NH—R ⁶ —NHC (═O) R ¹² ”, the general formula “R ¹¹ NHC (═O) —R ⁷ —C (═O) NHR ¹² ”.
In the formula, R ¹¹ and R ¹² are each a hydrocarbon group which may have a substituent, and examples thereof include those similar to R ¹ described above. R ⁶ and R ⁷ are each a divalent hydrocarbon group, and the number of carbon atoms thereof is preferably 1 to 10, and more preferably 1 to 8.

  Specific examples of compounds having two or more amine nitrogen atoms in one molecule include methylenebisstearic acid amide, ethylene bisstearic acid amide, ethylene biscaprylic acid amide, ethylene bislauric acid amide, and ethylene bisbehenic acid amide. , Methylene bishydroxy stearic acid amide, hexamethylene bis stearic acid amide, hexamethylene bis behenic acid amide, hexamethylene bis hydroxy stearic acid amide; N, N-distearyl adipic acid amide, N, N-distearyl sebacic acid amide, etc. Is mentioned.

  Among the above fatty acid amides, primary amides and secondary amides are preferable, primary amides are more preferable, saturated fatty acid monoamides, non-volatile amides from the viewpoints of handleability, stability and spinnability of the raw material mixture. Saturated fatty acid monoamides are particularly preferred, with behenamide being most preferred.

  Moreover, as fatty acid amides, if the carbon number is too small, the heat resistance of the phenolic fiber may be reduced, and if the carbon number is too large, the compatibility with the phenol resin used as the raw material for the phenolic fiber is reduced. There is a fear. Therefore, as for fatty acid amides, that whose carbon number is 12-30 by the whole molecule is preferred, and what is 18-24 is more preferred. Fatty acid amides may be used alone or in combination of two or more.

“Phosphoric acid” of the phosphoric acid esters used as a blend in the present invention is a general term for various oxo acids generated by hydrolysis of tetraphosphorus decaoxide (P ₄ O ₁₀ ), and is represented by the following chemical formula. Orthophosphoric acid (a), pyrophosphoric acid (diphosphoric acid) (b), triphosphoric acid (c), tetraphosphoric acid (d), metaphosphoric acid (e) and the like.

[Wherein m represents the number of repetitions. ]

  In the present invention, the “phosphate esters” mean those in which one or more of —OH in phosphoric acid is substituted with a group represented by the following general formula (1) (phosphate esters) or salts thereof.

[Wherein R ¹³ is a hydrocarbon group having 4 or more carbon atoms which may have a hetero atom (atom other than carbon and hydrogen), AO is an oxyalkylene group having 2 to 4 carbon atoms, n Is the average number of moles added and represents a number from 0 to 100. ]

In the formula (1), as the hydrocarbon group for R ¹³ , an alkyl group, an alkenyl group, an aryl group, a group in which a part of hydrogen atoms of the alkyl group is substituted with an aryl group, or a part of hydrogen atoms in an alkenyl group Are groups substituted with an aryl group.

When the hydrocarbon group for R ¹³ is an alkyl group or an alkenyl group, R ¹³ preferably has 4 to 22 carbon atoms, and more preferably 8 to 18 carbon atoms.

When the hydrocarbon group of R ¹³ is an aryl group, the carbon number of R ¹³ is preferably 6 to 35, and more preferably 6 to 27. Specific examples include a phenyl group, a naphthyl group, a benzyl group, a tolyl group, and a xylyl group.

Regardless of the hydrocarbon group of R ¹³ , if the number of carbon atoms of R ¹³ exceeds the upper limit, compatibility with the phenol resin tends to decrease. When R ¹³ is an aryl group, the compatibility with the phenol resin is relatively better than when R ¹³ is an alkyl group or an alkenyl group.

  In the formula (1), examples of AO include an oxyethylene group, an oxypropylene group, and an oxybutylene group. Note that an oxygen atom in the oxyalkylene group is bonded to the phosphorus atom.

  In said formula (1), 0-50 are preferable and, as for n, 0-10 are more preferable.

  As phosphate esters, since mechanical strength is likely to increase particularly when a large-diameter phenolic fiber is used, at least one of —OH in orthophosphoric acid is substituted with the group represented by the above formula (1). (Orthophosphoric acid ester) or a salt thereof is preferred.

  Specific examples of the orthophosphoric acid ester include monoesters (f), diesters (g), and triesters (h) of orthophosphoric acid represented by the following general formula. Of these, monoesters and diesters of orthophosphoric acid are preferable.

[Wherein, R ¹³ , AO and n are the same as defined above. In the diester and triester, a plurality of — (AO) _n OR ¹³ may be the same or different from each other. ]

  Examples of the phosphate ester salt include alkali metal salts, alkaline earth metal salts, ammonium salts and amine salts of phosphate esters. Phosphate esters may be used alone or in combination of two or more.

[Process for producing phenolic fiber]
The phenolic fiber used in the present invention is a raw material mixing step of mixing the phenol resin obtained by the above method and the above blend, and the raw material mixture obtained in the raw material mixing step is spun to obtain a yarn. It can be produced through a spinning process.

<Raw material mixing process>
When melt-spinning, which is the most common spinning method in the spinning process described later, is performed by melt-mixing a phenol resin and a blend, either a novolak-type or resol-type phenol resin can be used as the phenol resin. However, the resol type is inferior in thermal stability to the novolak type, and the polymerization proceeds easily by heating during melting, so solidification in the melt spinning apparatus is inevitable, and continuous and stable spinning is performed. It is difficult. Therefore, it is particularly preferable to select a novolac type phenol resin in consideration of the ease of the process in industrial production and versatility.

  In the raw material mixing step, when the phenol resin and the compound are mixed, the amount of the phenol resin used is such that the proportion of the phenol resin in the obtained raw material mixture is 55% by mass to 99.9% by mass. The amount is preferably 70% by mass to 99% by mass, and more preferably 85% by mass to 95% by mass.

  The amount of the compound used is such that the ratio of the compound in the raw material mixture obtained (the ratio of the total of the compounds when using a plurality of compounds) is 0.1% by mass to 45% by mass. The amount is preferably 1% by mass to 30% by mass, and more preferably 5% by mass to 15% by mass. If the proportion of the blend is equal to or greater than the preferred lower limit, the effect of improving the mechanical strength when the phenolic fiber is increased in diameter is likely to be obtained. On the other hand, if the proportion of the blend is less than or equal to the preferable upper limit value, it is easy to maintain the characteristics such as heat resistance, flame retardancy, and chemical resistance of the phenol fiber.

  Specifically, the amount of fatty acid amides used is preferably an amount such that the ratio of fatty acid amides in the obtained raw material mixture is 0.1% by mass to 45% by mass, and preferably 1% by mass to 30% by mass. % Is more preferable, and an amount of 3% by mass to 10% by mass is particularly preferable.

  The amount of phosphate esters used is preferably, for example, an amount such that the proportion of phosphate esters in the obtained raw material mixture is 0.1% by mass to 45% by mass, and 1% by mass to 30% by mass. It is more preferable that the amount is 5% by mass to 20% by mass.

  Examples of the method of mixing the phenol resin and the compound include a method of melting and mixing the two, a method of dissolving and mixing both using a solvent, and the like. Among these, from the viewpoint of complexity of the process, environmental load, and economical efficiency, a method of melt-mixing both is preferable. An example of such melt mixing is a method of kneading both.

  The heat-kneading of the phenol resin and the compound can be performed using a known kneading apparatus, and examples of the kneading apparatus include an extruder-type kneader, a mixing roll, a Banbury mixer, and a high-speed biaxial continuous mixer. .

  What is necessary is just to select the temperature of heat-kneading suitably with the property of a raw material, etc., 200 degrees C or less is preferable and 140 to 180 degreeC is more preferable. By setting the temperature of the heat-kneading to a preferable upper limit value or less, thermal denaturation and deterioration due to exposure of the raw material to a high temperature can be easily suppressed. By setting the temperature of the heat-kneading to a preferable lower limit value or more, it becomes possible to efficiently mix both.

  In the method of dissolving and mixing a phenol resin and a blend using a solvent, the raw material mixture is obtained by dissolving and mixing both in a solvent that can dissolve both, and then removing the solvent by evaporation.

  Examples of the solvent capable of dissolving both include a solvent obtained by mixing one or two or more selected from ketone solvents, ether solvents, nitrogen-containing solvents, hydrocarbon solvents, ester solvents, alcohol solvents, and the like. It is done.

  In the dissolution and mixing of the phenol resin and the blend, it is preferable to gradually add the phenol resin and the blend while stirring the solvent. At that time, heating is effective if the phenol resin or the compound is hardly dissolved in the solvent. Further, by applying pressure, it is possible to heat the solvent at a temperature higher than the boiling point of the solvent at normal pressure, which is further effective. However, since exposure to the raw material at a high temperature may cause thermal denaturation and deterioration, it is preferable to perform the heating limitedly until the raw material is completely dissolved.

  The concentration of the phenol resin and the compound dissolved in the solvent is not particularly limited, and may be set as appropriate in consideration of the properties of the raw materials and the spinning method in the subsequent spinning step. In addition, from the point that it takes a lot of time and energy to recover the solvent to be removed by evaporation, it is preferable to set the concentrations of the phenol resin and the compound as high as possible in consideration of their respective solubilities.

  As a method of mixing the phenol resin and the compound, a method other than the melt mixing and dissolution mixing described above may be used. For example, when using a dry spinning, wet spinning or dry / wet spinning method as a spinning method in the subsequent spinning step, a raw material mixture solution obtained by dissolving and mixing both in a solvent capable of dissolving both the phenol resin and the compound is used. It may be prepared. The raw material mixture solution can be used directly as a stock solution for spinning.

  It is also effective to mix and mix the compound in the middle of the phenol resin synthesis reaction so long as the raw material does not deteriorate at the temperature during the synthesis reaction without inhibiting the synthesis reaction of the phenol resin. It is.

  In the raw material mixing step, even if any method is used to obtain the raw material mixture, known additives, plasticizers, compatibilizers, antioxidants, ultraviolet absorbers, penetrants, if necessary. Thickeners, antifungal agents, dyes, pigments, fillers and the like may be used.

  In particular, when the phenol resin and the fatty acid amides are melt-mixed and the melt viscosity of the fatty acid amides is extremely different from that of the phenol resin, it is preferable to use a compatibilizing agent. This can prevent separation during spinning.

<Spinning process>
In the spinning step, the raw material mixture obtained in the raw material mixing step is spun to obtain a yarn.

  As the spinning method, a known method can be appropriately selected in view of the properties of the raw material mixture, and examples thereof include wet spinning, dry spinning, dry / wet spinning, melt spinning, gel spinning, and liquid crystal spinning. . Of these, melt spinning is preferred because of the simplicity of the apparatus and economic advantages. When melt spinning is used as a spinning method, a general melt spinning apparatus can be used.

  As a melting apparatus of the melt spinning apparatus, a grid melter type, a single screw extruder method, a twin screw extruder method, a tandem extruder method, or the like can be used. In order to prevent oxidation of the molten raw material mixture, nitrogen substitution in the melt spinning apparatus may be performed, or an operation of removing a trace amount of residual solvent or monomers is performed using an extruder equipped with a vent. May be.

  In melt spinning, the temperature condition is preferably 120 ° C to 200 ° C, more preferably 140 ° C to 170 ° C. By setting the temperature condition to be equal to or higher than the preferable lower limit, spinning can be performed efficiently. By setting the temperature condition to a preferable upper limit value or less, thermal denaturation and deterioration can be easily suppressed, and the phenol resin and the compound are hardly separated.

  As the spinneret, a normal one can be used, and the hole diameter is preferably 0.05 mm or more and 1 mm or less, more preferably 0.07 mm or more and 0.5 mm or less, and L / D (length / diameter) of the capillary portion is 0.5 or more and 10 or less are preferable, and 1 or more and 5 or less are more preferable. By setting the pore diameter and L / D within the above preferred ranges, stable spinning can be achieved.

  In the case of a special fiber manufacturing method (for example, in the case of side-by-side conjugate fiber, core-sheath type conjugate fiber, sea-island type conjugate fiber, etc.), a conjugate base that combines a side-by-side type or seascore type or a third component polymer. Can also be used.

  The spinning speed is preferably 15 m / min or more and 3000 m / min or less, more preferably 30 m / min or more and 2000 m / min or less, and further preferably 50 m / min or more and 1600 m / min or less. By setting the spinning speed to a preferable lower limit value or more, spinning can be performed efficiently. By setting the spinning speed to a preferable upper limit value or less, the occurrence of yarn breakage during spinning can be suppressed.

<Curing process>
It is preferable that the step of producing the phenol fiber includes a curing step of curing the yarn obtained in the spinning step. By curing the yarn in the curing step, the phenol resin portion is mainly cross-linked, so that the mechanical strength of the thickened phenol fiber increases.

  When a novolac type phenol resin is used as a raw material phenol resin, a method of curing the yarn obtained in the spinning step is to immerse the yarn processed into a staple shape or a tow shape in the treatment liquid in the reaction vessel. A batch-type curing method, a bobbin-like or skein-like processed product is brought into contact with the treatment liquid, or a tow-like processed product is continuously brought into contact with the treatment liquid and cured. The method etc. are mentioned.

  The treatment liquid is composed of a catalyst and aldehydes.

  As a catalyst, the acidic catalyst and basic catalyst which were illustrated as what can be used when manufacturing a phenol resin are mentioned. Moreover, as aldehydes, the aldehydes illustrated as what can be used when manufacturing a phenol resin are mentioned.

  Curing is preferably performed in the liquid phase by heating at a temperature of 60 ° C. to 110 ° C. for 3 hours to 30 hours. Moreover, in this invention, you may harden | cure by heating in a gaseous phase.

  In the present invention, after the heating, washing with water and drying are performed, and a known post-curing treatment is performed such as further curing by heating at a temperature of 100 ° C. to 300 ° C. in an inert gas such as nitrogen, helium or carbon dioxide. be able to. By this post-curing treatment, the cross-linking of the phenol resin portion in the yarn further proceeds, and a phenol fiber having sufficient strength can be obtained.

  On the other hand, when a resol type phenol resin is used as a raw material phenol resin, the yarn can be cured by heat treatment by a wet heat method or a dry heat method.

  As heat treatment conditions, the temperature is preferably 100 ° C. to 220 ° C., more preferably 120 ° C. to 180 ° C., and the treatment time is preferably 5 minutes to 120 minutes, more preferably 20 minutes to 60 minutes.

The phenol fiber used in the present invention has a tensile modulus of 370 kgf / mm ^{2 to} 450 kgf / mm ² (more preferably 380 kgf / mm ^{2 to} 430 kgf / mm ² ) and an elongation of 8% to 30% (more preferably). Is preferably 10% to 25%). By using phenolic fibers having a tensile elastic modulus and elongation in this range, the nonwoven fabric can be easily processed even if the single fiber fineness is 7 dtex or more.

  The fiber length of the phenolic fiber is preferably 35 mm or more (more preferably 50 mm or more), and is preferably 130 mm or less (more preferably 100 mm or less, more preferably 80 mm or less). If the fiber length is less than 35 mm, the fibers cannot be sufficiently entangled, and the resulting nonwoven fabric may have a low tensile strength. When the fiber length exceeds 130 mm, for example, fiber cutting or damage during needle punching becomes severe, and the tensile strength may also be lowered.

  The presence or absence of the crimp of the phenol fiber is not particularly limited. In order to enhance the entanglement of the fiber, the phenolic fiber may have a crimp. On the other hand, the phenolic fiber containing the blend is soft even if it has a large diameter, and is excellent in confounding property. Therefore, in the present invention, a phenolic fiber having no crimp can be used.

[Nonwoven fabric processing]
The method for processing a phenol-based fiber into a nonwoven fabric is not particularly limited as long as it can prevent fiber breakage at the time of processing and can sufficiently entangle between fibers, and examples thereof include a needle punch method and a water punch method. It is done. The needle punch method is preferable because the density of the nonwoven fabric obtained can be adjusted by adjusting the needle density and the needle depth according to the change in the fiber diameter.

When the nonwoven fabric processing is performed by the needle punch method, the needle density is 370 / inch ² or more (more preferably 450 / inch ² or more), the needle depth is 5 mm or more (more preferably 7 mm or more), 30 mm or less (more Preferably it is 20 mm or less. By setting the needle density to 370 / inch ² or more, the entanglement between the fibers increases, and the bulk density of the nonwoven fabric increases accordingly. If the needle density is too high, fiber breakage may occur, and the bulk density and tensile strength of the resulting nonwoven fabric may be reduced. Therefore, the upper limit of the needle density is preferably 700 / inch ² . Moreover, when the needle depth is less than 5 mm, the nonwoven fabric may be bulky. When the needle depth exceeds 30 mm, needle breakage is likely to occur. Moreover, there exists a tendency for a stripe to increase in a nonwoven fabric.

  Using the phenol-based fiber nonwoven fabric according to the present invention, for example, a dust filter for capturing a solid suspended in a gas; a mist filter for capturing a liquid mist such as moisture or oil floating in the gas; a coal boiler or a garbage incinerator Heat-resistant filter that collects high-temperature dust, etc. discharged from the environment; chemicals that can be used for filtration of liquids and gases that contain acid, alkali, and other chemicals that can change the appearance and physical properties of ordinary filters Various filters such as a neutral filter can be produced. By using the phenol-based fiber nonwoven fabric of the present invention, a filter having excellent mechanical strength and a small pressure loss can be obtained. Therefore, the filter can be used over a long period of time.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples, and can be implemented with appropriate modifications within a range that can be adapted to the above and the gist described below. These are all included in the technical scope of the present invention.

  First, a method for measuring the fineness, tensile elastic modulus, elongation, nonwoven fabric basis weight, tensile strength, bulk density, and pressure loss (pressure loss) coefficient of “phenolic fibers” produced in production examples and examples will be described below. .

(Fineness of phenolic fiber)
It measured using DC11B denier computer (made by search Co., Ltd.).

(Tensile modulus of phenol fiber)
It measured based on JISL1015 using RTG-1210 Tensilon universal testing machine (made by A & D Co., Ltd.).

(Elongation of phenolic fiber)
It measured based on JISL1015 using RTG-1210 Tensilon universal testing machine (made by A & D Co., Ltd.).

(Nonwoven fabric weight)
The mass per unit area was measured and determined in units of g / m ² . The mass was measured in a completely dry state at 100 ° C.

(Tensile strength of nonwoven fabric)
Five test pieces (width 25 mm, length 100 mm) were cut from the width direction and length direction of the nonwoven fabric, respectively, and an Instron type tensile tester (for example, “STM-T-200BP” manufactured by Toyo Baldwin Co., Ltd.) The both ends of the test piece are gripped with a chuck, the breaking strength is measured with a chuck interval of 50 mm, a tensile speed of 20 mm / min (elongation rate 40% / min), and the value is the cross-sectional area (width × thickness) of the test piece. (Unit N / cm ² ). The thickness was measured using a disk with an area of 4 cm ^{2 and} a load applied to the nonwoven fabric of 9 gf / cm ² . Of the average value of the tensile strength of the test piece cut in the width direction and the average value of the tensile strength of the test piece cut in the length direction, the smaller value was defined as the tensile strength of the nonwoven fabric of the present invention.

(Bulk density of nonwoven fabric)
The bulk density was determined in units of kg / m ³ by dividing the basis weight by the thickness. The thickness was measured using a disk with an area of 4 cm ^{2 and} a load applied to the nonwoven fabric of 9 gf / cm ² .

(Pressure loss coefficient of nonwoven fabric)
A non-woven fabric is cut out into a perfect circle with a diameter of 72 mm and set in an aeration pressure loss measurement jig, and a compressed air of 0.1 MPa is provided between the true circle with a diameter of 50.5 mm and the non-woven fabric with a diameter of 72 mm as a measurement surface. The pressure loss was measured by flowing air with a wind speed of 30 cm / second, and the value was determined by dividing the value by the wind speed and thickness (unit: mmAq · s / cm ² ). The measurement was performed at a temperature of 25 ° C. and a humidity of 50%. The thickness was measured in the same manner as that used when measuring the bulk density.

(Production Example 1 Production of phenol fiber 1)
1000 parts by weight of phenol, 733 parts by weight of formalin 733 parts by weight and 5 parts by weight of oxalic acid were charged into a reaction vessel equipped with a reflux condenser, heated from room temperature to 100 ° C. over 40 minutes, and further reacted at 100 ° C. for 4 hours. Then, the mixture was heated to 200 ° C., dehydrated and concentrated, and then cooled to obtain a novolac type phenol resin.

  475 kg of the above-mentioned novolak type phenol resin and 25 kg of behenamide are charged into a biaxial kneader (high-speed biaxial continuous mixer), kneaded (melted and mixed) at 150 ° C., cooled to room temperature, and light yellow transparent A block-like product was obtained. In addition, behenic acid amide (BNT-22H) manufactured by Nippon Seika Co., Ltd. was used as the behenic acid amide.

  Next, this block-like product is coarsely pulverized and melted at 200 ° C. using a melt spinning apparatus (grid melter type), and the melt obtained by the melting has a pore diameter of 0.1 mm maintained at 170 ° C., A yarn was obtained by spinning (melt spinning) at a spinning speed of 75 m / min while maintaining a constant discharge rate from a spinneret with L / D = 3 and 10 holes.

  The obtained yarn was cut into a length of 70 mm, placed in a container, immersed in an aqueous solution of 14% by mass hydrochloric acid and 8% by mass formaldehyde for 30 minutes at room temperature, heated to 98 ° C. in 2 hours, and further 98 Curing was performed by holding at 2 ° C. for 2 hours.

  Subsequently, after taking out the hardened | cured material obtained from the said container and fully washing with water, neutralization was performed for 30 minutes at 60 degreeC with 3 mass% ammonia aqueous solution. Thereafter, it was thoroughly washed with water again and dried at 90 ° C. for 30 minutes to obtain a phenol fiber 1 having a single fiber fineness of 11 dtex, a fiber length of 70 mm, and no fiber crimp.

The phenolic fiber 1 obtained had a tensile modulus of 395 kgf / mm ² and an elongation of 12%.

(Production Example 2 Production of phenolic fiber 2)
A phenolic fiber 2 having a single fiber fineness of 7.7 dtex, a fiber length of 70 mm, and no fiber crimp was obtained in the same manner as in Production Example 1 except that the diameter of the spinneret was changed to 0.07 mm and the discharge amount was reduced. .

The obtained phenolic fiber 2 had a tensile modulus of 390 kgf / mm ² and an elongation of 25%.

(Production Example 3 Production of phenolic fiber 3)
In the production example 1, the mixing amount of the novolak type phenol resin was 450 kg, and the single fiber fineness was 11 dtex in the same manner as in the production example 1 except that the phosphate ester represented by the following formula was changed to 50 kg instead of the behenamide 25 kg. A phenol fiber 3 having a fiber length of 70 mm and no fiber crimp was obtained. The phosphoric acid ester is “Phosphanol (registered trademark) SM-172” (manufactured by Toho Chemical Industry Co., Ltd .; the mass ratio of the monoester of the following formula (1A) to the diester of the following formula (1B) is 1A / 1B = 1. / 1 mixture).

The obtained phenol fiber 3 had a tensile modulus of 427 kgf / mm ² and an elongation of 10%.

(Production Example 4 Production of phenolic fiber 4)
In Production Example 1, a single fiber fineness of 11 dtex, a fiber length of 70 mm, and no fiber crimping were carried out in the same manner as in Production Example 1 except that 475 kg of novolak-type phenol resin and 25 kg of behenamide were used, and 500 kg of novolak-type phenol resin was used. Phenol fiber 4 was obtained.

The obtained phenol fiber 4 had a tensile modulus of 469 kgf / mm ² and an elongation of 4%.

Example 1
Using the phenolic fiber 1 produced in Production Example 1, the back and front treatment was performed with a needle punch machine under the conditions of a needle density of 500 / inch ² , a needle depth of 12 mm (back) and 7 mm (front), and a dry basis weight of 540 g / A nonwoven fabric with m ² and a bulk density of 82.4 kg / m ³ was obtained. Table 1 shows the properties of the obtained nonwoven fabric.

(Example 2)
In Example 1, instead of the phenolic fiber 1 produced in Production Example 1, the same procedure as in Example 1 was used except that the phenolic fiber 2 produced in Production Example 2 was used, and the dry basis weight 535 g / m ² , bulk density A nonwoven fabric of 80.3 kg / m ³ was obtained. Table 1 shows the properties of the obtained nonwoven fabric.

(Example 3)
A dry basis weight of 550 g / m ² and a bulk density of 81.8 kg / min were used in the same manner as in Example 1 except that the phenolic fiber 3 obtained in Production Example 3 was used instead of the phenolic fiber 1 used in Example 1. A non-woven fabric of m ³ was obtained. Table 1 shows the properties of the obtained nonwoven fabric.

(Comparative Example 1)
A monofilament fineness of 5.6 dtex, a fiber length of 70 mm, a phenolic fiber without fiber crimp (manufactured by Gunei Chemical Industry Co., Ltd., Kynol (registered trademark) KF-0570), and a needle density of 500 Back / front treatment was performed under the conditions of book / inch ² , needle depth 12 mm (back), 7 mm (front) to obtain a nonwoven fabric having a dry basis weight of 575 g / m ² and a bulk density of 83.7 kg / m ³ . Table 1 shows the properties of the obtained nonwoven fabric.

(Comparative Example 2)
Using the phenolic fiber 4 produced in Production Example 4, the back and front treatment was performed with a needle punch machine under the conditions of a needle density of 650 needles / inch ² , a needle depth of 15 mm (back) and 10 mm (front), and a dry basis weight of 585 g / A nonwoven fabric with m ² and a bulk density of 110.0 kg / m ³ was obtained. Table 1 shows the properties of the obtained nonwoven fabric.

(Comparative Example 3)
For the purpose of obtaining a nonwoven fabric having the same bulk density as in Example 1 using a phenolic fiber 4 manufactured in Production Example 4 and a needle punch machine, the needle density is 500 / inch ² , which is the same as in Example 1, and the needle Backside treatment was performed under conditions of a depth of 12 mm (back) and 7 mm (front) to try to make a nonwoven fabric, but it was not possible to make a nonwoven fabric.

Claims (3)

Phenolic fibers of single fiber fineness 7dtex~22dtex obtained nonwoven fabric, basis weight ^{400g / m 2 ~2000g / m 2} , tensile strength 30 N / cm ² or more, a bulk density of 100 kg / m ³ or less, per unit thickness ventilation A phenol-based fiber nonwoven fabric having a pressure loss coefficient of 0.3 mmAq · s / cm ² or less.   The phenolic fiber nonwoven fabric according to claim 1, wherein the phenolic fiber is produced using a mixture in which a fatty acid amide and / or a phosphate ester is mixed with a phenol resin.   A filter produced using the phenol-based fiber nonwoven fabric according to claim 1.