CN110373737B - Method for preparing melamine modified urea-formaldehyde fiber by multiple addition - Google Patents
Method for preparing melamine modified urea-formaldehyde fiber by multiple addition Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G12/00—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C08G12/02—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes
- C08G12/26—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds
- C08G12/34—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds and acyclic or carbocyclic compounds
- C08G12/36—Ureas; Thioureas
- C08G12/38—Ureas; Thioureas and melamines
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/06—Wet spinning methods
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/78—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolycondensation products
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Abstract
The invention discloses a method for preparing melamine modified urea-formaldehyde fiber by multiple additions, which comprises the steps of respectively adding melamine and aldehydes (a solution) into two parts of macromolecular aqueous solution, and respectively adding urea and aldehydes (a solution) into alkaline catalysts for reacting for different times; and mixing the solution A and the solution B, adding an acid catalyst and a certain amount of urea to continue to react, adding an alkaline catalyst and the rest aldehyde compound to react, spinning, heating and curing to obtain the modified urea-formaldehyde fiber. The invention reasonably designs the reaction process, improves the spinnability of the urea-formaldehyde molecules, increases the crosslinking degree, has the advantages of low cost, flame retardance of the fiber, heat insulation, no molten drop, no toxicity in combustion and the like when being used as the three-dimensional crosslinking fiber, and has wide application prospect.
Description
Technical Field
The invention belongs to the field of preparation of special fibers, and particularly relates to a method for preparing melamine modified urea-formaldehyde spinning solution by multiple addition, wet spinning and thermosetting to obtain functional modified urea-formaldehyde fibers.
Background
The three-dimensional cross-linked fiber has the characteristics of intrinsic flame retardance, heat insulation, high carbonization yield and the like, and has potential application value in the fields of functional textiles, carbon fibers and activated carbon fibers. However, the development of the crosslinked fiber is very slow because the crosslinked fiber and the oriented fiber have different preparation methods and structural characteristics.
Phenolic fibers were the first three-dimensionally crosslinked organic fibers [ Economy J, Clark R A. US patent, 3650102 ], the advent of the fiber broke through the inherent concept that three-dimensional crosslinked resins could not be formed into fibers. The melamine resin fiber has good flame retardance, acid and alkali resistance, high temperature resistance and other properties due to the three-dimensional network structure formed by the condensation reaction of melamine and formaldehyde. Melamine resin (MF) fibers, also known as melamine fibers, are a type of crosslinked fibers that follow phenolic fibers. The flame-retardant polyester has good flame retardance, the limit oxygen index of the flame-retardant polyester reaches 32, and no toxic gas is generated during combustion or contact with flame; the fuel is not melted and does not drop in the combustion process, so that secondary fire can be avoided; meanwhile, the melamine fiber can be used for a long time at the temperature of 200 ℃, and the size and the tensile strength are hardly changed [ Rogofeng ]. Advanced technical synthetic fibers [ J ]. High-tech fibers and applications, 2000 (4): 1-8], the melamine fiber can be carbonized and activated at higher temperature to prepare carbon fiber or porous carbon fiber material. The melamine fiber can be widely applied to the fields of flame-retardant textiles, high-temperature filtration, purification and adsorption and the like.
The urea-formaldehyde resin is widely used for manufacturing furniture and household appliances, mechanical parts, electrical fittings, various buttons, cover plates and the like as urea-formaldehyde plastic, wood adhesive and the like, is rapidly developed due to low price and good flame retardance, but has no related report on the application of the urea-formaldehyde resin in the aspect of fibers. The invention combines the advantages of urea formaldehyde and melamine to prepare the melamine modified urea formaldehyde fiber by a multiple addition method.
Disclosure of Invention
The invention provides a method for preparing melamine modified urea-formaldehyde fiber by multiple additions, which comprises the steps of adding melamine, urea and aldehyde compounds into a high molecular aqueous solution, reacting, blending, performing an acid reaction process, adjusting to an alkaline condition again, adding the rest aldehyde compounds, reacting to obtain a spinning solution, and preparing the three-dimensional crosslinked modified urea-formaldehyde fiber by wet spinning and thermocuring. The method provides a method for preparing melamine modified urea-formaldehyde fiber by multiple additions.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a method for preparing melamine modified urea-formaldehyde fiber by multiple addition comprises the following steps:
(1) dissolving water-soluble polymer in water to obtain water-soluble polymer aqueous solution, dividing the water-soluble polymer aqueous solution into A, B parts of solution equally, adding melamine, aldehydes and an alkaline catalyst into the solution A, and reacting at 50-95 ℃ for 0.4-10h to obtain solution A; adding urea, an aldehyde compound and an alkaline catalyst into the solution B, and reacting for 0.5-8h at 45-95 ℃ to obtain a solution B; mixing the solution A and the solution B, adding an acid catalyst to adjust the pH value to acidity, adding urea at 40-95 ℃ and continuously reacting for 0.1-7h to obtain a modified urea-formaldehyde resin solution;
(2) adding an alkaline catalyst to adjust the urea-formaldehyde resin solution to be alkaline, slowly adding an aldehyde compound, reacting for a period of time at 35-95 ℃ to obtain a modified urea-formaldehyde spinning solution, and performing coagulation bath by using a wet spinning process to obtain urea-formaldehyde nascent fiber;
(3) and washing and drying the nascent fiber, and then heating and curing the nascent fiber in an oven according to a certain heating rate to obtain the modified urea-formaldehyde fiber.
Further, in the step (1), the water-soluble polymer is one of PVA, PEG, polyvinyl formal, PVP, water-soluble modified starch or water-soluble modified cellulose, and the mass content of the polymer in the water-soluble polymer aqueous solution is 1-30%.
Further, the aldehyde compound is one of formaldehyde, glutaraldehyde, acetaldehyde or paraformaldehyde; the alkaline catalyst is one of sodium hydroxide, potassium hydroxide, triethanolamine, sodium bicarbonate, magnesium hydroxide or calcium hydroxide; the acidic catalyst is one of hydrochloric acid, sulfuric acid, phosphoric acid or oxalic acid.
Furthermore, the molar ratio of the melamine to the aldehyde compound in the solution of the part A in the step (1) is 1 (0.7-1.9), and the mass ratio of the polymer to the melamine is 1: (0.1-4); the molar ratio of urea to aldehyde compounds in the solution of the part B is 1: (0.7-1.9), the mass ratio of the polymer to the urea is 1 (0.2-10).
Further, in the step (1), the amount of the added urea after the solution A and the solution B are mixed accounts for 5% -50% of the amount of the added urea substance in the solution B.
Further, in the step (1), the pH value range of the solution A is 7.4-11, the pH value range of the solution B is 7.5-10.5, and the solution A and the solution B are mixed and then added with an acid catalyst to adjust the pH value range to 4.0-6.9.
Further, adding an alkaline catalyst in the step (2) to adjust the pH value of the urea-formaldehyde resin solution to be 7.4-10.5, wherein the reaction time is 0.4-8 h.
Furthermore, the addition amount of the aldehyde compound in the step (2) is based on the urea in the step (1), and the mass ratio of the urea to the aldehyde compound is 1 (0.3-2).
Further, the coagulating bath for wet spinning in the step (2) is a saturated sodium sulfate aqueous solution, and boric acid with the weight content of 0.1-5% is added, the temperature is 10-60 ℃, and the winding speed is 10-500 m/min.
Further, in the step (3), the drying temperature of the nascent fiber in the vacuum oven is 20-40 ℃, the heating rate is 1-30 ℃/min, the temperature is increased to 150-.
The invention has the following beneficial effects: the raw materials of the urea and the aldehyde compound are cheap and easy to obtain, strong acid, strong alkali or corrosive conditions are not needed, and the reaction conditions are mild; urea and aldehydes are added for multiple times, so that the control of the reaction degree is facilitated, and the molecular structure is optimized; the addition of the melamine improves the functionality of molecules, is beneficial to the increase of the crosslinking degree, is beneficial to the reaction with aldehyde and reduces the content of free aldehyde; the urea-formaldehyde molecules in the obtained spinning solution are of a high-molecular-weight linear structure, the obtained spinning solution has high viscosity and excellent spinnability, can be directly spun without further treatment, has mild spinning conditions and high spinning speed, the obtained nascent fiber only needs to be thermally cured to obtain the modified urea-formaldehyde fiber, and the curing and crosslinking are simple and easy; the obtained modified urea-formaldehyde fiber is a three-dimensional cross-linked fiber, does not need to be added with a flame retardant, has excellent flame retardant performance, high limit oxygen index, can be extinguished after leaving flame, releases very little toxic and harmful gas during combustion, has high flame retardant safety, excellent heat insulation performance and increased mechanical property of the fiber.
Detailed Description
The present invention will be further described with reference to the following examples, which are intended to be illustrative only and not to be limiting of the invention in any way, and any person skilled in the art can modify the present invention by applying the teachings disclosed above and applying them to equivalent embodiments with equivalent modifications. Any simple modification or equivalent changes made to the following embodiments according to the technical essence of the present invention, without departing from the technical spirit of the present invention, fall within the scope of the present invention.
Example 1
The method for preparing the melamine modified urea-formaldehyde fiber by multiple additions comprises the following steps:
(1) dissolving PVA in water to obtain a 1wt% PVA aqueous solution, equally dividing the PVA aqueous solution into two parts, adding melamine, acetaldehyde and potassium hydroxide into one part, reacting for 0.4h at the temperature of 50 ℃ and the pH value of 7.4, wherein the molar ratio of the melamine to the acetaldehyde is 1:0.7, and the mass ratio of the PVA to the melamine is 1: 0.1; adding urea and formaldehyde (the molar ratio is 1: 0.7) into the other part, wherein the mass ratio of PVA to urea is 1:0.2, then adding sodium hydroxide aqueous solution, adjusting the pH value to 7.5, and reacting for 0.5h at 45 ℃; after the two solutions are blended, hydrochloric acid is added to adjust the pH value to 4.0, urea (accounting for 5 percent of the amount of the urea substance added under the alkaline condition) is added at 40 ℃, and the reaction is carried out for 0.1 hour;
(2) adding the calcium hydroxide aqueous solution again, adjusting the pH value to 7.4, then adding paraformaldehyde (the mass ratio of the urea to the paraformaldehyde added in the step (1) is 1: 0.3), and reacting at 35 ℃ for 0.4h to obtain a modified urea-formaldehyde solution with the aldehyde content of 0.09%;
(3) and (3) carrying out wet spinning on the obtained spinning solution, using a saturated sodium sulfate aqueous solution with the weight content of 0.1% boric acid as a coagulating bath, obtaining a nascent fiber at the winding speed of 10m/min at the temperature of 10 ℃, drying at the temperature of 20 ℃, heating to 150 ℃ at the speed of 1 ℃/min, keeping the temperature for 0.1h, naturally cooling, and taking out to obtain the modified urea-formaldehyde fiber.
The diameter of the prepared modified urea-formaldehyde fiber is 14 microns, the tensile strength is 341MPa, the elongation at break is 33 percent, and the LOI value of the fiber is 33.
Example 2
The method for preparing the melamine modified urea-formaldehyde fiber by multiple additions comprises the following steps:
(1) dissolving PEG in water to obtain 30wt% of PEG aqueous solution, equally dividing the PEG aqueous solution into two parts, adding melamine, formaldehyde and sodium hydroxide into one part, reacting for 10 hours at the conditions of pH 11 and 95 ℃, wherein the molar ratio of the melamine to the formaldehyde is 1:1.9, and the mass ratio of the PEG to the melamine is 1: 4; adding urea and paraformaldehyde (the molar ratio is 1: 1.9) into the other part, wherein the mass ratio of PEG to urea is 1: 10; then adding a potassium hydroxide aqueous solution, adjusting the pH value to 10.5, and reacting for 8 hours at 95 ℃; after the two solutions are blended, adding sulfuric acid to adjust the pH value to 6.9, adding urea (accounting for 50 percent of the amount of the urea substance added under the alkaline condition) at 95 ℃, and reacting for 7 hours;
(2) adding the sodium hydroxide aqueous solution again, adjusting the pH value to 10.5, then adding formaldehyde (the mass ratio of the urea to the formaldehyde added in the step (1) is 1: 2), and reacting for 8 hours at 95 ℃ to obtain a modified urea-formaldehyde solution with the aldehyde content of 0.08%;
(3) and (3) carrying out wet spinning on the obtained spinning solution, using a saturated sodium sulfate aqueous solution with the weight content of 5% boric acid as a coagulating bath, obtaining a nascent fiber at the winding speed of 500m/min at the temperature of 60 ℃, drying at the temperature of 40 ℃, heating at the temperature of 30 ℃/min to 230 ℃, keeping the temperature for 2h, naturally cooling, and taking out to obtain the urea-formaldehyde fiber.
The prepared urea-formaldehyde fiber has the diameter of 22 microns, the tensile strength of 346MPa, the elongation at break of 19 percent and the LOI value of 31.
Example 3
The method for preparing the melamine modified urea-formaldehyde fiber by multiple additions comprises the following steps:
(1) dissolving polyvinyl formal in water to obtain 20wt% of polyvinyl formal aqueous solution, equally dividing the polyvinyl formal aqueous solution into two parts, adding melamine, glutaraldehyde and calcium hydroxide into one part, and reacting for 4 hours at the conditions of pH 8.5 and 65 ℃, wherein the molar ratio of the melamine to the glutaraldehyde is 1: 1.3; the mass ratio of polyvinyl formal to melamine is 1: 3; adding urea and glutaraldehyde (the molar ratio is 1: 1.1) into the other part, wherein the mass ratio of the polyvinyl formal to the urea is 1: 5; then adding triethanolamine, adjusting the pH value to 8.5, and reacting for 3h at 90 ℃; after the two solutions are blended, adding phosphoric acid to adjust the pH value to 5, adding urea (accounting for 25 percent of the amount of the urea substance added under the alkaline condition) at 55 ℃, and reacting for 2 hours;
(2) adding the potassium hydroxide aqueous solution again, adjusting the pH value to 8.5, then adding acetaldehyde (the mass ratio of the urea to the acetaldehyde added in the step (1) is 1: 0.5), and reacting for 4 hours at 75 ℃ to obtain a modified urea-formaldehyde solution with the aldehyde content of 0.1%;
(3) and (3) carrying out wet spinning on the obtained spinning solution, using a saturated sodium sulfate aqueous solution with the weight content of 3% boric acid as a coagulating bath, obtaining a nascent fiber at the winding speed of 300m/min at the temperature of 50 ℃, drying at the temperature of 30 ℃, heating at the temperature of 20 ℃/min to 210 ℃, keeping the temperature for 1h, naturally cooling, and taking out to obtain the modified urea-formaldehyde fiber.
The diameter of the prepared modified urea-formaldehyde fiber is 33 microns, the tensile strength is 284MPa, the elongation at break is 21 percent, and the LOI value of the fiber is 32.
Example 4
The method for preparing the melamine modified urea-formaldehyde fiber by multiple additions comprises the following steps:
(1) dissolving PVP in water to obtain 10wt% PVP aqueous solution, equally dividing into two parts, adding melamine, paraformaldehyde and magnesium hydroxide into one part, reacting for 3h at the conditions of pH 9 and 55 ℃, wherein the molar ratio of the melamine to the paraformaldehyde is 1: 1.1; the mass ratio of PVP to melamine is 1: 0.2; adding urea and acetaldehyde (the molar ratio is 1: 1.1) into the other part, wherein the mass ratio of PVP to urea is 1: 3; then adding sodium bicarbonate, adjusting the pH value to 8.5, and reacting for 2h at 90 ℃; after the two solutions are blended, adding oxalic acid to adjust the pH value to 5.5, adding urea (15 percent of the amount of the urea substance added under the alkaline condition) at 75 ℃, and reacting for 2 hours;
(2) adding triethanolamine again, adjusting the pH value to 8.5, then adding paraformaldehyde (the mass ratio of the urea to the paraformaldehyde added in the step (1) is 1: 0.5), and reacting for 4 hours at 75 ℃ to obtain a modified urea-formaldehyde solution with the aldehyde content of 0.12%;
(3) and (3) carrying out wet spinning on the obtained spinning solution, using a saturated sodium sulfate aqueous solution with the weight content of 3% boric acid as a coagulating bath, obtaining a nascent fiber at the winding speed of 200m/min at the temperature of 50 ℃, drying at the temperature of 30 ℃, heating to 180 ℃ at the speed of 20 ℃/min, keeping the temperature for 1h, naturally cooling, and taking out to obtain the modified urea-formaldehyde fiber.
The diameter of the prepared modified urea-formaldehyde fiber is 17 microns, the tensile strength is 320MPa, the elongation at break is 13%, and the LOI value of the fiber is 34.
Example 5
The method for preparing the melamine modified urea-formaldehyde fiber by multiple additions comprises the following steps:
(1) dissolving water-soluble starch in water to obtain 10wt% water-soluble starch aqueous solution, equally dividing into two parts, adding melamine, formaldehyde and sodium bicarbonate into one part, reacting for 5h at 75 ℃ with pH of 9.1, wherein the molar ratio of the melamine to the formaldehyde is 1: 0.9; wherein the mass ratio of the water-soluble starch to the melamine is 1: 0.2; adding urea and paraformaldehyde (the molar ratio is 1: 1.1) into the other part, wherein the mass ratio of the water-soluble starch to the urea is 1: 0.5; then adding magnesium hydroxide, adjusting the pH value to 8.5, and reacting for 2h at 90 ℃; after the two solutions are blended, adding sulfuric acid to adjust the pH value to 5.5, adding urea (accounting for 19 percent of the amount of the urea substance added under the alkaline condition) at 55 ℃, and reacting for 2 hours;
(2) adding sodium bicarbonate again, adjusting the pH value to 8.5, then adding glutaraldehyde (the mass ratio of the urea to the glutaraldehyde added in the step (1) is 1: 0.5), and reacting for 4 hours at 75 ℃ to obtain a modified urea-formaldehyde solution with the aldehyde content of 0.06%;
(3) and (3) carrying out wet spinning on the obtained spinning solution, using a saturated sodium sulfate aqueous solution with the weight content of 2% boric acid as a coagulating bath, obtaining a nascent fiber at the winding speed of 180m/min at the temperature of 40 ℃, drying at the temperature of 30 ℃, heating to 190 ℃ at the speed of 20 ℃/min, keeping the temperature for 1h, naturally cooling, and taking out to obtain the modified urea-formaldehyde fiber.
The prepared modified urea-formaldehyde fiber has the diameter of 22 microns, the tensile strength of 236MPa, the elongation at break of 17 percent and the LOI value of 33.
Example 6
The method for preparing the melamine modified urea-formaldehyde fiber by multiple additions comprises the following steps:
(1) dissolving water-soluble cellulose in water to obtain 18wt% water-soluble cellulose aqueous solution, equally dividing into two parts, adding melamine, paraformaldehyde and triethanolamine into one part, and reacting at 85 deg.C and pH of 8.0 for 0.9h, wherein the molar ratio of melamine to aldehyde is 1: 1.2; the mass ratio of the water-soluble cellulose to the melamine is 1: 1; adding urea and glutaraldehyde (molar ratio is 1: 1.2) into the other part, wherein the mass ratio of the water-soluble cellulose to the urea is 1: 2; then adding calcium hydroxide, adjusting the pH value to 8.5, and reacting for 2h at 90 ℃; after the two solutions are blended, adding sulfuric acid to adjust the pH value to 5.5, adding urea (accounting for 45 percent of the amount of the urea substance added under the alkaline condition) at 76 ℃, and reacting for 3 hours;
(2) adding magnesium hydroxide again, adjusting the pH value to 8.5, then adding formaldehyde (the mass ratio of the urea to the formaldehyde added in the step (1) is 1: 0.8), and reacting for 4 hours at 75 ℃ to obtain a modified urea-formaldehyde solution with the aldehyde content of 0.1%;
(3) and (3) carrying out wet spinning on the obtained spinning solution, using a saturated sodium sulfate aqueous solution containing 0.9 wt% of boric acid as a coagulating bath, obtaining a nascent fiber at the winding speed of 50m/min at the temperature of 40 ℃, drying at the temperature of 30 ℃, heating to 190 ℃ at the speed of 20 ℃/min, keeping the temperature for 1h, naturally cooling, and taking out to obtain the modified urea-formaldehyde fiber.
The diameter of the prepared modified urea-formaldehyde fiber is 27 microns, the tensile strength is 230MPa, the elongation at break is 40%, and the LOI value of the fiber is 31.
Example 7
The method for preparing the melamine modified urea-formaldehyde fiber by multiple additions comprises the following steps:
(1) dissolving water-soluble cellulose in water to obtain 18wt% water-soluble cellulose aqueous solution, equally dividing into two parts, adding melamine, acetaldehyde and potassium hydroxide into one part, reacting for 4.5h at pH 10 and 80 ℃, wherein the molar ratio of the melamine to the aldehydes is 1: 1; wherein the mass ratio of the water-soluble cellulose to the melamine is 1: 0.4; adding urea and formaldehyde (the molar ratio is 1: 1.2) into the other part, wherein the mass ratio of the water-soluble cellulose to the urea is 1: 3; then adding sodium hydroxide, adjusting the pH value to 8.5, and reacting for 2h at 90 ℃; after the two solutions are blended, adding oxalic acid to adjust the pH value to 5.5, adding urea (accounting for 49 percent of the amount of the urea substance added under the alkaline condition) at 76 ℃, and reacting for 3 hours;
(2) adding magnesium hydroxide again, adjusting the pH value to 8.5, then adding acetaldehyde (the mass ratio of the urea to the acetaldehyde added in the step (1) is 1: 0.8), and reacting for 4 hours at 75 ℃ to obtain a modified urea-formaldehyde solution with the aldehyde content of 0.08%;
(3) and (3) carrying out wet spinning on the obtained spinning solution, using a saturated sodium sulfate aqueous solution containing 1.9 wt% of boric acid as a coagulating bath, obtaining a nascent fiber at the winding speed of 50m/min at the temperature of 40 ℃, drying at the temperature of 30 ℃, heating to 190 ℃ at the speed of 20 ℃/min, keeping the temperature for 1h, naturally cooling, and taking out to obtain the urea-formaldehyde fiber.
The diameter of the prepared urea-formaldehyde fiber is 24 microns, the tensile strength is 310MPa, the elongation at break is 29 percent, and the LOI value of the fiber is 32.
Example 8
The method for preparing the melamine modified urea-formaldehyde fiber by multiple additions comprises the following steps:
(1) dissolving PVA in water to obtain 8wt% PVA solution, equally dividing into two parts, adding melamine, acetaldehyde and potassium hydroxide into one part, and reacting at 60 deg.C and pH of 7.8 for 3.8 hr, wherein the molar ratio of melamine to aldehyde is 1: 0.9; wherein the mass ratio of PVA to melamine is 1: 0.9; adding urea and formaldehyde (the molar ratio is 1: 1.2) into the other part, wherein the mass ratio of PVA to urea is 1: 3.6; then adding sodium hydroxide, adjusting the pH value to 8.5, and reacting for 2h at 90 ℃; after the two solutions are blended, hydrochloric acid is added to adjust the pH value to 5.5, urea (accounting for 33 percent of the amount of the urea substance added under the alkaline condition) is added at 83 ℃, and the reaction is carried out for 3 hours;
(2) adding sodium hydroxide again, adjusting the pH value to 8.5, then adding formaldehyde (the mass ratio of the urea to the formaldehyde added in the step (1) is 1: 0.8), and reacting for 2h at 75 ℃ to obtain a modified urea-formaldehyde solution with the aldehyde content of 0.11%;
(3) and (3) carrying out wet spinning on the obtained spinning solution, using a saturated sodium sulfate aqueous solution with the weight content of 2% boric acid as a coagulating bath, obtaining a nascent fiber at the winding speed of 20m/min at the temperature of 40 ℃, drying at the temperature of 30 ℃, heating to 190 ℃ at the temperature of 20 ℃/min, keeping the temperature for 1.5h, naturally cooling, and taking out to obtain the urea-formaldehyde fiber.
The diameter of the prepared urea-formaldehyde fiber is 22 microns, the tensile strength is 280MPa, the elongation at break is 31 percent, and the LOI value of the fiber is 33.
The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (5)
1. A method for preparing melamine modified urea-formaldehyde fiber by multiple addition is characterized by comprising the following steps:
(1) dissolving water-soluble polymer in water to obtain water-soluble polymer aqueous solution, dividing the water-soluble polymer aqueous solution into A, B parts of solution equally, adding melamine, aldehydes and an alkaline catalyst into the solution A, and reacting at 50-95 ℃ for 0.4-10h to obtain solution A; adding urea, an aldehyde compound and an alkaline catalyst into the solution B, and reacting for 0.5-8h at 45-95 ℃ to obtain a solution B; mixing the solution A and the solution B, adding an acid catalyst to adjust the pH value to acidity, adding urea at 40-95 ℃ and continuously reacting for 0.1-7h to obtain a modified urea-formaldehyde resin solution;
(2) adding an alkaline catalyst to adjust the urea-formaldehyde resin solution to be alkaline, slowly adding an aldehyde compound, reacting for a period of time at 35-95 ℃ to obtain a modified urea-formaldehyde spinning solution, and performing coagulation bath by using a wet spinning process to obtain urea-formaldehyde nascent fiber;
(3) washing and drying the nascent fiber, and then heating and curing the nascent fiber in an oven according to a certain heating rate to obtain modified urea-formaldehyde fiber;
the molar ratio of melamine to aldehyde compounds in the solution of the part A in the step (1) is 1 (0.7-1.9), and the mass ratio of macromolecules to melamine is 1 (0.1-4); the molar ratio of the urea to the aldehyde compounds in the solution of the part B is 1 (0.7-1.9), and the mass ratio of the polymer to the urea is 1 (0.2-10);
in the step (1), the amount of added urea after the solution A and the solution B are mixed accounts for 5-50% of the amount of added urea substances in the solution B;
in the step (1), the pH value range of the solution A is 7.4-11, the pH value range of the solution B is 7.5-10.5, and the solution A and the solution B are mixed and then added with an acid catalyst to adjust the pH value range to 4.0-6.9;
adding an alkaline catalyst in the step (2) to adjust the pH value range of the urea-formaldehyde resin solution to 7.4-10.5, wherein the reaction time is 0.4-8 h;
the addition amount of the aldehyde compound in the step (2) is based on the urea in the step (1), and the mass ratio of the urea to the aldehyde compound is 1 (0.3-2).
2. The multiple addition process for preparing melamine modified urea formaldehyde fiber according to claim 1, wherein: the water-soluble polymer in the step (1) is one of PVA, PEG, polyvinyl formal, PVP, water-soluble modified starch or water-soluble modified cellulose, and the mass content of the polymer in the water-soluble polymer aqueous solution is 1-30%.
3. The multiple addition process for preparing melamine modified urea formaldehyde fiber according to claim 1, wherein: the aldehyde compound is one of formaldehyde, glutaraldehyde, acetaldehyde or paraformaldehyde; the alkaline catalyst is one of sodium hydroxide, potassium hydroxide, triethanolamine, sodium bicarbonate, magnesium hydroxide or calcium hydroxide; the acidic catalyst is one of hydrochloric acid, sulfuric acid, phosphoric acid or oxalic acid.
4. The multiple addition process for preparing melamine modified urea formaldehyde fiber according to claim 1, wherein: and (3) the coagulating bath for wet spinning in the step (2) is a saturated sodium sulfate aqueous solution, and boric acid with the weight content of 0.1-5% is added, the temperature is 10-60 ℃, and the winding speed is 10-500 m/min.
5. The multiple addition process for preparing melamine modified urea formaldehyde fiber according to claim 1, wherein: and (3) drying the nascent fiber in the vacuum oven at the temperature of 20-40 ℃, heating at the rate of 1-30 ℃/min to the temperature of 150-.
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| CN201910694107.3A CN110373737B (en) | 2019-07-30 | 2019-07-30 | Method for preparing melamine modified urea-formaldehyde fiber by multiple addition |
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| CN201910694107.3A CN110373737B (en) | 2019-07-30 | 2019-07-30 | Method for preparing melamine modified urea-formaldehyde fiber by multiple addition |
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| CN110714233B (en) * | 2019-11-27 | 2022-07-15 | 中原工学院 | Method for producing phenolic/melamine fibres by copolymerisation |
| CN110846737A (en) * | 2019-11-27 | 2020-02-28 | 中原工学院 | Method for preparing phenolic modified melamine fiber by one-step method |
| CN110846740B (en) * | 2019-11-27 | 2022-07-15 | 中原工学院 | Method for preparing phenol modified melamine fiber by single-kettle method |
| CN110820074B (en) * | 2019-11-27 | 2022-07-15 | 中原工学院 | Method for preparing urea compound modified melamine fiber by base catalysis |
| CN117050440B (en) * | 2023-09-07 | 2024-02-06 | 揭阳市顺佳和化工有限公司 | Modified amino molding compound and preparation method thereof |
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