CN109183409B - Method for preparing flame-retardant viscose fiber from melamine grafted oxidized viscose fiber and flame-retardant viscose fiber - Google Patents
Method for preparing flame-retardant viscose fiber from melamine grafted oxidized viscose fiber and flame-retardant viscose fiber Download PDFInfo
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- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
- D06M13/322—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing nitrogen
- D06M13/35—Heterocyclic compounds
- D06M13/355—Heterocyclic compounds having six-membered heterocyclic rings
- D06M13/358—Triazines
- D06M13/364—Cyanuric acid; Isocyanuric acid; Derivatives thereof
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- D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
- D06M11/58—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with nitrogen or compounds thereof, e.g. with nitrides
- D06M11/64—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with nitrogen or compounds thereof, e.g. with nitrides with nitrogen oxides; with oxyacids of nitrogen or their salts
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- D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
- D06M13/322—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing nitrogen
- D06M13/402—Amides imides, sulfamic acids
- D06M13/432—Urea, thiourea or derivatives thereof, e.g. biurets; Urea-inclusion compounds; Dicyanamides; Carbodiimides; Guanidines, e.g. dicyandiamides
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- D06M2101/00—Chemical constitution of the fibres, threads, yarns, fabrics or fibrous goods made from such materials, to be treated
- D06M2101/02—Natural fibres, other than mineral fibres
- D06M2101/04—Vegetal fibres
- D06M2101/06—Vegetal fibres cellulosic
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- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
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- D06M2200/00—Functionality of the treatment composition and/or properties imparted to the textile material
- D06M2200/30—Flame or heat resistance, fire retardancy properties
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- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
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- D06M2200/00—Functionality of the treatment composition and/or properties imparted to the textile material
- D06M2200/50—Modified hand or grip properties; Softening compositions
Abstract
The invention provides a flame-retardant viscose fiber, which is made to have flame retardancy by grafting melamine on the viscose fiber. The method for preparing the flame-retardant viscose fiber by the melamine grafted oxidized viscose fiber comprises the following steps: (1) preparing pretreated viscose fibers, adding the viscose fibers into a sodium hydroxide solution, boiling for reaction, taking out after the reaction is finished, cleaning and drying for later use; (2) preparing oxidized viscose fibers, dispersing the pretreated viscose fibers in a dilute nitric acid solution, stirring, ventilating and oxidizing, taking out the fibers after the reaction is finished, and washing and spin-drying the fibers for later use; (3) preparing a melamine ethanol solution, and adjusting the pH value of the solution to 4-5.5 by using dilute hydrochloric acid; preparing an ethanol solution of N, N' -dicyclohexylcarbodiimide; adding the melamine ethanol solution into a reaction vessel, dispersing the oxidized viscose fiber in the melamine ethanol solution, stirring and ventilating, adding the N, N' -dicyclohexylcarbodiimide ethanol solution in batches, and reacting at constant temperature. The oxygen index of the obtained product can reach 32-40%.
Description
Technical Field
The invention relates to a method for preparing flame-retardant viscose fibers by melamine grafted oxidized viscose fibers, belonging to the field of flame-retardant materials and preparation methods thereof.
Background
The viscose fiber is a regenerated cellulose fiber which is prepared by using natural cellulose as a raw material, preparing soluble cellulose sulfonate through the working procedures of alkalization, aging, sulfonation and the like, and then spinning, is one of the oldest chemical fiber varieties, and has the characteristics of good heat resistance, high strength, good moisture absorption, static resistance, good dyeing property, easiness in modification and the like. Due to the excellent properties, the viscose fiber is widely applied to various fields such as civil use, industry, medicine, fire fighting and the like.
With the continuous development of social economy and science and technology, the requirements on the demand and the service performance of fibers and products thereof are continuously improved. The fire caused by the combustion of fiber products is in a trend of multiple occurrence, and the public safety and the life and property safety of people are seriously influenced. Developed countries such as Europe and America set up specific requirements and limits on the combustion performance of fibers and products thereof according to different uses of textiles, establish a series of mandatory legal rules, and China also has a track with the world and gradually establishes and perfects related flame retardant standards and rules. For example, in 2007, China is out and implements the national mandatory flame retardant Standard GB 20286-.
The viscose fiber is easy to burn when meeting open fire, and has no molten drop and ash when burned. The limit oxygen index of the common viscose fiber is only 18 percent, and the common viscose fiber belongs to flammable materials. According to statistics of relevant departments, fire caused by indoor ornaments and textiles is the first place, and huge losses are caused to lives and properties of people. Therefore, the flame retardant modification treatment method has great significance for carrying out flame retardant modification treatment on widely applied viscose fiber products, reducing the occurrence of fire accidents, guaranteeing the life safety of human beings and avoiding economic loss.
According to the flame retardant modification method of viscose fiber and products thereof, the method is generally divided into 3 types: post-treatment flame-retardant modification, blending addition method, graft copolymerization flame-retardant modification.
1. Post-treatment flame retardant modification
The fabric is subjected to surface treatment in the post-finishing process of the fabric, so that the fabric has flame retardant property.
And (3) soaking the nascent viscose fiber in the flame retardant bath solution, padding, drying and heat setting to prepare the flame-retardant viscose fiber. The process has the advantages of simple process, low cost, low strength loss of the viscose fiber and obvious flame retardant effect. For example, when the viscose fabric is treated by using the guanidine phosphate FRDL-112, when the plant increment reaches 9 percent after flame-retardant finishing, the LOI value (limiting oxygen index) can reach more than 41 percent, but the washing fastness is not good, the loss is easy, and the flame-retardant effect is not durable.
In recent years, a new inorganic nanoparticle and viscose fiber composite flame-retardant material has appeared, and Hribernik and the like adopt a sol-gel method to enable silicon dioxide nanoparticles to grow on the surface of viscose fibers, cover the surface layers of the fibers, and then the silicon dioxide nanoparticles enter the surface layers of the fibers after being treated by sodium hydroxide, so that the decomposition temperature of the fibers is improved by 20 ℃ by the fibers prepared by the method, and meanwhile, the nanoparticles play a role in isolating air.
2. Blending addition method
The blending addition method is that before the viscose fiber is spun, a certain amount of flame retardant is added in the preparation process of the spinning solution, and the viscose fiber with the flame retardant effect is obtained through spinning. Generally, the addition amount of the viscose blend flame retardant is large (10% -20%) in order to obtain good flame retardant effect, and a series of changes are made on the after-finishing process of the viscose. The addition method has influence on the mechanical property of the viscose fiber, has higher requirement on the stability of the flame retardant, is acid and alkali resistant, needs to be well dispersed in viscose and is beneficial to spinning. The modified flame retardant is uniformly dispersed in the fiber, so that the viscose fiber prepared by the blending addition method has the permanent flame retardant characteristic.
A high-efficiency viscose fiber flame retardant cannot be obtained in the international market, the 2 types of flame retardants which are widely applied in the prior art are THPX polycondensate and MDPA derivatives respectively, but modified fibers release harmful gases by combustion, and the processing technology is complex, so that the application of the modified fibers is limited.
Representative blend-type flame-retardant viscose fibers that have been put into practical use in foreign flame-retardant research include: austria Lenzing flame retardant viscose fiber and japan Polynosic viscose fiber, both of which are applied organic phosphorus or halogen organic compounds; french TF-80 fiber and American PER viscose fiber are applied with organic ester flame retardant; the flame retardant fiber Visil produced by Kemiraoy in Finland uses sodium silicate of water glass.
The Nanjing chemical fiber company, Shanghai chemical fiber II factory and Dandong chemical fiber company successively utilize imported or domestic pyrophosphates flame retardants to perform tests or produce flame retardant products of viscose fibers in small batches. However, since the import price of the flame retardant is too high, the quality problems of large particle size, wide particle size distribution, poor stability of the flame retardant dispersion and the like exist in the flame retardant produced in China, and finally, large-scale industrial production is not carried out.
In China, the Beijing Sailolan flame retardant fiber company Limited cooperates with the original academy of industry, Zhang Wenzhen and the like synthesize the nitrogen-silicon composite flame retardant and the viscose spinning solution to be blended and spun into filaments, and the flame retardant effect is improved by utilizing the synergistic effect of 3 elements of phosphorus, nitrogen and silicon. The flame retardant effect that the limiting oxygen index is more than 27% can be achieved under the condition that the adding proportion of the flame retardant is less than 20%, and the comprehensive mechanical property is slightly reduced.
In 2010, ran national celebration and the like disclose that fibers spun by adding silicon, phosphorus and nitrogen flame retardants (> 20%) into a spinning solution have a good flame retardant effect and improved mechanical properties.
The plum-silk and the like are spun by using a silicon-nitrogen flame retardant and adopting a pre-spinning injection method, the LOI value reaches 30% when the content of the flame retardant is 15%, and the product quality reaches the first-class standard of the national standard. The injection method before spinning is adopted, the process flow is short, the waste and the addition amount of the flame retardant are reduced, and in addition, the silicon nitrogen flame retardant has good compatibility with viscose, so that the influence of the silicon nitrogen flame retardant on the physical and mechanical properties of the fiber is reduced, and the physical properties of the product are better improved.
In recent years, melding flame retardant modification is carried out on viscose fibers by utilizing alkoxy cyclotriphosphazene, and the viscose fibers with additive addition amounts of 8.2%, 10.0% and 18.2% measured by a Limiting Oxygen Index (LOI) method and a 45-degree inclined combustion method belong to flame retardant fibers, wherein the LOI is not less than 28%. The flame-retardant fiber starts to generate chemical reaction at 290 ℃, the fiber is promoted to be dehydrated and carbonized in advance, an inexhaustible heat absorption and meteorological flame-retardant mechanism is provided, in addition, the carbon residue rate of the fiber is increased by 16%, and a remarkable condensed phase mechanism is provided, which shows that the alkoxy cyclotriphosphazene has multiple mechanisms for the flame retardance of the viscose fiber.
Graft copolymerization flame-retardant modification
The graft copolymerization flame-retardant modification method is to add an active monomer which can generate copolymerization reaction with cellulose molecules, such as vinyl phosphate ester, into viscose (graft modification is carried out before spinning), or to copolymerize with ethylene monomer first and then react with a flame retardant.
The phosphorus content of the fiber reaches 3.5 percent, the LOI value reaches 28 percent, the flame retardant effect is durable, and the modified fiber has the defect that the mechanical strength is obviously reduced.
The viscose fiber and O, O-diethyl-O-allyl thiophosphate are used for grafting copolymerization, the flame retardant property of the obtained finished fiber is increased along with the increase of the grafting rate, the carbon residue rate is greatly increased, and the LOI value measured by a vertical combustion method can reach 28%. The crystallinity and the crystal form of the grafted fiber are not changed, and the grafted monomer reacts on the surface without changing the internal structure of the fiber.
(MDPA) and warship fibers are subjected to graft copolymerization modification, infrared analysis shows that the flame retardant is successfully grafted to the viscose fibers, the LOI value of the modified fibers reaches 30%, the thermal stability of the fibers is improved, after 50 times of washing, the LOI value is kept at about 26.5%, and only the mechanical properties of the modified fibers are slightly reduced.
The graft copolymerization flame-retardant modification method has better flame-retardant property and lasting effect, but the structure of the lower skin layer is changed by grafting, so that the structure is damaged to a certain extent, and the mechanical property is reduced to a certain extent compared with that of the post-finishing flame-retardant modification method.
To sum up
The post-treatment flame-retardant modification is to apply a flame retardant to the fiber formed by primary spinning, and then to prepare the flame-retardant viscose fiber through the working procedures of squeezing, drying and the like, so that the surface of the flame-retardant viscose fiber has flame retardant property. The flame retardant has the advantages of simple process, low cost, convenient operation and the like, has good flame retardant effect, but has high flame retardant ratio, great influence on the strength, hand feeling and other properties of the fabric, poor washing fastness, easy loss of the flame retardant, and non-lasting flame retardant property, so the flame retardant is limited in actual production.
The blending flame-retardant modification is to mix the additive flame retardant and the viscose stock solution and then carry out wet spinning, wherein the flame retardant is left in the fiber after passing through a coagulating bath. Generally, the addition amount of the viscose fiber blending type flame retardant is large (10% -20%) to obtain good flame retardant effect, and the after-finishing process of the viscose fiber is changed. In the production of the fiber, the improvement of the flame retardant property of the product is in conflict with the improvement of the physical and mechanical properties of the fiber. Increasing the flame retardant content in the fiber will inevitably reduce the physical and mechanical properties of the product.
The existing graft copolymerization flame-retardant modification method is to add an active monomer which can generate copolymerization reaction with cellulose molecules, such as vinyl phosphate ester, into viscose (before spinning), or to copolymerize with ethylene monomer firstly and then react with a flame retardant. Although good flame retardant effect is achieved and the effect lasts for a long time, the mechanical property is reduced.
Disclosure of Invention
In order to solve the above technical problems, a first object of the present invention is to provide a flame retardant viscose fiber, and a second object of the present invention is to provide a method for preparing a flame retardant viscose fiber from a melamine grafted oxidized viscose fiber.
In order to achieve the first object of the present invention, the present invention provides a flame retardant viscose fiber method, which is characterized in that: the melamine is grafted on the viscose fibers so that the viscose fibers have flame retardancy.
In the scheme, the method comprises the following steps: the grafting ratio of the melamine is 4-13%.
The second purpose of the invention is realized by a method for preparing flame-retardant viscose fibers by melamine grafted oxidized viscose fibers, which is characterized by comprising the following steps:
(1) preparing pretreated viscose fiber, adding the viscose fiber into a sodium hydroxide solution, heating to boil, keeping boiling for 40-120min, taking out, cleaning, and drying for later use;
(2) preparing oxidized viscose fibers, dispersing the pretreated viscose fibers in a dilute nitric acid solution, ventilating, stirring for oxidation reaction, taking out the fibers after the reaction is finished, and washing and spin-drying the fibers for later use;
(3) preparing a melamine ethanol solution, and adjusting the pH value of the solution to 4-5.5 by using dilute hydrochloric acid; preparing an ethanol solution of N, N' -Dicyclohexylcarbodiimide (DCC);
adding a melamine ethanol solution into a reaction vessel, dispersing oxidized viscose fibers in the melamine ethanol solution, stirring and ventilating, adding N, N' -Dicyclohexylcarbodiimide (DCC) ethanol solution in batches, controlling the temperature to be 35-60 ℃, reacting at the constant temperature of 35-60 ℃ after the addition is finished, washing and drying to obtain the product.
According to the invention, the chemical reaction between the viscose macromolecular chain and the flame retardant melamine is realized by adopting graft copolymerization flame-retardant modification, the viscose textile is modified, the reactive group with flame retardant property is tightly combined on the viscose macromolecular by means of a covalent bond, the flame retardance is durable, and the influence on the mechanical property of the grafted and modified viscose is small. Compared with the blending method, the graft copolymerization method has the advantages that the flame retardant is combined with the fiber through a covalent bond, the structure is firm, and the flame retardant effect is durable. The melamine and its salt fire retardant has the characteristics of low smoke density, low smoke toxicity, low corrosivity, low water solubility, high fire retardant efficiency, good coloring capability and excellent electrical performance.
In the scheme, the method comprises the following steps: in the step (1), the mass concentration of the sodium hydroxide solution is 0.4-0.6%, the mass volume ratio of the viscose fiber to the sodium hydroxide solution is 3-8g/100ml, and the viscose fiber and the sodium hydroxide solution are washed by clear water.
In the scheme, the method comprises the following steps: in the step (2), the volume concentration of the dilute nitric acid solution is 0.5-3%, the volume ratio of the mass of the pretreated viscose fiber to the volume of the dilute nitric acid solution is 1kg:30L-50L, the ventilation quantity is 8-20 times/h of the volume of the dilute nitric acid, the reaction temperature is 60-80 ℃, the reaction time is 1-3h, and the washing is carried out by using clean water.
In the step (2), the oxidation rate is 5-16%. And when the oxidation rate reaches 5% -16%, the reaction is finished.
In the scheme, the method comprises the following steps: in the step (3), the mass concentration of the melamine ethanol solution is 1-10%, the mass concentration of the N, N '-Dicyclohexylcarbodiimide (DCC) ethanol solution is 30-60%, and the volume concentration of ethanol for preparing the melamine ethanol solution and the N, N' -Dicyclohexylcarbodiimide (DCC) is 50-80%;
when feeding, the mass ratio of the melamine to the viscose is 1:5-20(Kg/Kg),
the N, N '-dicyclohexylcarbodiimide ethanol solution is added according to the proportion that 2 to 5L of N, N' -dicyclohexylcarbodiimide ethanol solution is added into every 1Kg of viscose fiber.
In the scheme, the method comprises the following steps: in the step (3), the ventilation amount is 8-20 times of the volume of the melamine ethanol solution per hour, and the constant-temperature reaction time is 1-3 hours.
In the scheme, the method comprises the following steps: after the reaction in the step (3), washing the oxidized viscose fiber grafted with melamine by using an ethanol solution, then washing the oxidized viscose fiber with the melamine by using clear water for three times, and then drying the oxidized viscose fiber in a vacuum drying oven at the temperature of 50-60 ℃ to obtain the melamine grafted rate of 4-13%.
In the scheme, the method comprises the following steps: in the step (3), the reaction solution after the reaction is used for recovering ethanol to prepare dicyclohexyl isourea.
Has the advantages that: the melamine grafted oxidized viscose fiber prepared by the invention can reach 32-40% of limit oxygen index through testing, is improved by 78-122% compared with viscose fiber, and has higher limit oxygen index than the blended flame-retardant viscose fiber obtained at present. The flame-retardant fabric has the advantages of simple process, low cost, convenient operation, good flame-retardant effect, low flame-retardant agent proportion, small influence on the strength, hand feeling and other properties of the fabric, good washability, washing continuous washing for 50 times, zero flame-retardant agent loss rate, lasting flame-retardant property and good mechanical property.
Detailed Description
The following examples further illustrate the invention.
Example 1
1. Preparation of pretreated viscose fibers
Preparing 0.5 mass percent sodium hydroxide solution, adding viscose fiber into the sodium hydroxide solution, adding 3g of viscose fiber into each 100ml of sodium hydroxide solution, heating to boil, keeping boiling and boiling for 40min, taking out, washing with a large amount of water for 6 times, and drying for later use.
2. Preparation of oxidized viscose fibers
Firstly, preparing a dilute nitric acid solution with the volume percentage concentration of 0.5%, placing the dilute nitric acid solution in a sandwich reactor with a ventilating coil pipe at the bottom, then dispersing pretreated fibers in the dilute nitric acid solution according to the mass of the pretreated fibers/volume ratio of the dilute nitric acid solution of 1kg:50L, ventilating and stirring, wherein the ventilation amount is 8-20 times of the volume of the dilute nitric acid solution per hour, heating to 60 ℃, and reacting at constant temperature for 3 hours. The oxidation rate reaches 12 percent. After the reaction is finished, the fiber is taken out, washed for 3 times by purified water with the mass 10 times that of the viscose fiber, and then dried by a drying machine, and the oxidized viscose fiber is prepared and used for preparing the grafted melamine flame-retardant viscose fiber in the next step.
3. Preparation of grafted Melamine viscose fiber
Firstly, preparing 1 percent by mass of melamine ethanol solution by using 80 percent by volume of ethanol, and then adjusting the pH value to 4-5.5 by using dilute hydrochloric acid.
Then, ethanol with the volume concentration of 80% is used for preparing N, N' -Dicyclohexylcarbodiimide (DCC) ethanol solution with the mass percentage concentration of 30%.
Then according to the mass of the viscose: the mass ratio of melamine is 1:5, firstly pumping a melamine ethanol solution into a sandwich reactor with a ventilating coil pipe at the bottom, then dispersing oxidized viscose fibers in the solution, controlling the temperature to be 35-60 ℃, stirring and ventilating, adding N, N ' -Dicyclohexylcarbodiimide (DCC) ethanol solution in three batches when the ventilation amount is 8-20 times/small of the volume of the melamine ethanol solution, adding the total amount of the N, N ' -dicyclohexylcarbodiimide ethanol solution according to the proportion of adding 5L of the N, N ' -dicyclohexylcarbodiimide ethanol solution into 1kg of the viscose fibers, controlling the temperature to be 35-60 ℃ during feeding, and keeping the temperature to be 35 ℃ for constant temperature reaction for 3 hours after the feeding is finished.
And after the reaction is finished, respectively collecting the reaction liquid and the oxidized viscose fiber grafted with melamine, and recovering ethanol and preparing dicyclohexyl isourea from the collected reaction liquid.
Washing the collected oxidized viscose fiber grafted with melamine with ethanol with the volume 10-15 times of the mass of the viscose fiber, and then adding pure water with the mass 30 times of the mass of the viscose fiber for three times of washing. And respectively collecting the washing liquid and the washed grafted oxidized fiber, purifying the collected washing liquid, and discharging after reaching the standard. And (3) sending the collected and washed grafted oxidized fiber into a vacuum oven to be dried at 50-60 ℃, thus obtaining the grafted melamine viscose fiber. The melamine grafting ratio of the fiber was 8%. The oxygen index was tested as: 32 percent.
Example 2
1. Preparation of pretreated viscose fibers
Preparing a sodium hydroxide solution with the mass concentration of 0.4%, adding viscose into the sodium hydroxide solution, adding 8g of viscose into each 100ml of the sodium hydroxide solution, heating to boil, keeping boiling for 120min, taking out, washing with a large amount of water for 8 times, taking out and drying for later use.
2. Preparation of oxidized viscose fibers
Preparing a dilute nitric acid solution with the volume percentage concentration of 3%, placing the dilute nitric acid solution in a sandwich reactor with a ventilating coil pipe at the bottom, dispersing pretreated fibers in the dilute nitric acid solution according to the mass of the pretreated fibers/volume ratio of the dilute nitric acid solution of 1kg:30L, ventilating, stirring and ventilating the dilute nitric acid solution with the ventilating amount of 8-20 times of the volume of the dilute nitric acid per hour, heating to 70 ℃, and reacting at constant temperature for 2 hours. The oxidation rate reaches 11.5 percent. After the reaction is finished, the fiber is taken out, washed for 5 times by purified water with the mass 10 times that of the viscose fiber, and then dried by a drying machine, and the oxidized viscose fiber is prepared and used for preparing the grafted melamine flame-retardant viscose fiber in the next step.
3. Preparation of grafted Melamine viscose fiber
Firstly, preparing 10 percent by mass of melamine ethanol solution by using 50 percent by volume of ethanol, and then adjusting the pH value to 4-5.5 by using dilute hydrochloric acid.
Then, ethanol with the volume concentration of 50 percent is used for preparing N, N' -Dicyclohexylcarbodiimide (DCC) ethanol solution with the mass percentage concentration of 60 percent.
Then according to the mass of the viscose: the mass ratio of melamine is 1:20, firstly, melamine ethanol solution is pumped into a sandwich reactor with a ventilating coil pipe at the bottom, then oxidized viscose fiber is dispersed in the sandwich reactor, the temperature is controlled to be 35-60 ℃, stirring is carried out, the ventilation amount is 8-20 times/hour of the volume of the melamine ethanol solution, N, N ' -Dicyclohexylcarbodiimide (DCC) ethanol solution is added in three batches, the total adding amount of the N, N ' -dicyclohexylcarbodiimide ethanol solution is added according to the proportion of adding 2L of the volume of the N, N ' -dicyclohexylcarbodiimide ethanol solution into every 1kg of the viscose fiber, the temperature is controlled to be 35-60 ℃ during adding, and the temperature is kept at 60 ℃ for constant temperature reaction for 1h after adding.
And after the reaction is finished, respectively collecting the reaction liquid and the oxidized viscose fiber grafted with melamine, and recovering ethanol and preparing dicyclohexyl isourea from the collected reaction liquid.
Washing the collected oxidized viscose fiber grafted with melamine with ethanol with the volume 12 times that of the viscose fiber, and then adding pure water with the mass 25 times that of the viscose fiber for three times of washing. And respectively collecting the washing liquid and the washed grafted oxidized fiber, purifying the collected washing liquid, and discharging after reaching the standard. And (3) sending the collected and washed grafted oxidized fiber into a vacuum oven to be dried at 50-60 ℃, thus obtaining the grafted melamine viscose fiber. The melamine grafting ratio of the fiber was 12%. The oxygen index was tested as: 38 percent.
Example 3
1. Preparation of pretreated viscose fibers
Preparing a sodium hydroxide solution with the mass concentration of 0.6%, adding viscose into the sodium hydroxide solution, adding 5g of viscose into each 100ml of the sodium hydroxide solution, heating to boil, keeping boiling for 80min, taking out, washing with a large amount of water for 8 times, taking out and drying for later use.
2. Preparation of oxidized viscose fibers
Firstly, preparing a dilute nitric acid solution with the volume percentage concentration of 0.8%, placing the dilute nitric acid solution in a sandwich reactor with a ventilating coil pipe at the bottom, then dispersing pretreated fibers in the dilute nitric acid solution according to the pretreated fiber mass/dilute nitric acid solution volume ratio of 1kg:40L, ventilating, stirring and ventilating the dilute nitric acid solution with the ventilating amount of 8-20 times of the volume of the dilute nitric acid per hour, heating to 80 ℃, and reacting at constant temperature for 1 hour. The oxidation rate reaches 9 percent. After the reaction is finished, the fiber is taken out, washed for 5 times by purified water with the mass 10 times that of the viscose fiber, and then dried by a drying machine, and the oxidized viscose fiber is prepared and used for preparing the grafted melamine flame-retardant viscose fiber in the next step.
3. Preparation of grafted Melamine viscose fiber
Firstly, preparing a melamine ethanol solution with the mass percentage concentration of 3% by using ethanol with the volume concentration of 60%, and then adjusting the pH value to 4-5.5 by using dilute hydrochloric acid.
Then, ethanol with the volume concentration of 60 percent is used for preparing N, N' -Dicyclohexylcarbodiimide (DCC) ethanol solution with the mass percentage concentration of 40 percent.
Then according to the mass of the viscose: the mass ratio of melamine is 1:3, firstly pumping a melamine ethanol solution into a sandwich reactor with a ventilating coil pipe at the bottom, then dispersing oxidized viscose fibers in the solution, controlling the temperature to be 35-60 ℃, stirring, adding N, N ' -Dicyclohexylcarbodiimide (DCC) ethanol solution in three batches, adding the total amount of the N, N ' -dicyclohexylcarbodiimide ethanol solution according to the proportion of adding 4L of the N, N ' -dicyclohexylcarbodiimide ethanol solution into every 1kg of viscose fibers, controlling the temperature to be 35-60 ℃ during feeding, and keeping the temperature at 40 ℃ for constant temperature reaction for 2 hours after the feeding is finished.
And after the reaction is finished, respectively collecting the reaction liquid and the oxidized viscose fiber grafted with melamine, and recovering ethanol and preparing dicyclohexyl isourea from the collected reaction liquid.
Washing the collected oxidized viscose fiber grafted with melamine with ethanol with the volume 10 times that of the viscose fiber, and then adding pure water with the mass 20 times that of the viscose fiber for three times of washing. And respectively collecting the washing liquid and the washed grafted oxidized fiber, purifying the collected washing liquid, and discharging after reaching the standard. And (3) sending the collected and washed grafted oxidized fiber into a vacuum oven to be dried at 50-60 ℃, thus obtaining the grafted melamine viscose fiber. The grafting rate of the fiber melamine is 4-13%. The oxygen index was tested as: 40 percent.
While embodiments of the invention have been shown and described, it will be understood by those skilled in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (7)
1. A flame retardant viscose fiber characterized by: the melamine is grafted on the viscose fiber so that the viscose fiber has flame retardance, and the preparation method comprises the following steps:
(1) preparing pretreated viscose fiber, adding the viscose fiber into a sodium hydroxide solution, heating to boil, keeping boiling for 40-120min, taking out, cleaning, and drying for later use;
(2) preparing oxidized viscose fibers, dispersing the pretreated viscose fibers in a dilute nitric acid solution, ventilating, stirring for oxidation reaction, taking out the fibers after the reaction is finished, and washing and spin-drying the fibers for later use; the volume concentration of the dilute nitric acid solution is 0.5-3%, the mass ratio of the pretreated viscose fiber to the dilute nitric acid solution is 1kg:30-50L, and the ventilation volume is 8-20 times/h of the volume of the dilute nitric acid;
(3) preparing a melamine ethanol solution, and adjusting the pH value of the solution to 4-5.5 by using dilute hydrochloric acid; preparing an ethanol solution of N, N' -Dicyclohexylcarbodiimide (DCC); the mass concentration of the melamine ethanol solution is 1-10%, the mass concentration of the N, N '-Dicyclohexylcarbodiimide (DCC) ethanol solution is 30-60%, and the volume concentration of ethanol used for preparing the melamine ethanol solution and the N, N' -Dicyclohexylcarbodiimide (DCC) is 50-85%;
when feeding, the mass ratio of the melamine to the viscose is 1:5-20(Kg/Kg),
adding the N, N '-dicyclohexylcarbodiimide ethanol solution according to the proportion that 2-5L of N, N' -dicyclohexylcarbodiimide ethanol solution is added into every 1Kg of viscose fiber;
adding a melamine ethanol solution into a reaction vessel, dispersing oxidized viscose fibers in the melamine ethanol solution, stirring and ventilating, adding N, N' -Dicyclohexylcarbodiimide (DCC) ethanol solution in batches, controlling the temperature to be 35-60 ℃, reacting at the constant temperature of 35-60 ℃ after the addition is finished, washing and drying to obtain the product.
2. The flame retardant viscose fiber according to claim 1, wherein: in the step (1), the mass concentration of the sodium hydroxide solution is 0.4-0.6%, the mass volume ratio of the viscose fiber to the sodium hydroxide solution is 3-8g/100ml, and the viscose fiber and the sodium hydroxide solution are washed by clear water.
3. The flame retardant viscose fiber according to claim 2, wherein: in the step (2), the reaction temperature is 60-80 ℃, the reaction time is 1-3h, and the washing is carried out by adopting clean water.
4. A flame retardant viscose fiber according to claim 3 wherein: in the step (2), the oxidation rate is 5-16%.
5. The flame retardant viscose fiber according to claim 4, wherein: in the step (3), the ventilation amount is 8-20 times of the volume of the melamine ethanol solution per hour, and the constant-temperature reaction time is 1-3 hours.
6. The flame retardant viscose fiber of claim 5 wherein: and (4) after the reaction in the step (3), washing the oxidized viscose fiber grafted with the melamine by using an ethanol solution, washing the oxidized viscose fiber with clear water for three times, and drying the oxidized viscose fiber in a vacuum drying oven at the temperature of 50-60 ℃.
7. The flame retardant viscose fiber of claim 6 wherein: in the step (3), the reaction solution after the reaction is used for recovering ethanol to prepare dicyclohexyl isourea.
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| CN105780175A (en) * | 2016-05-20 | 2016-07-20 | 天津工业大学 | Flame-retardant viscose fiber and preparation method thereof |
| CN107761386A (en) * | 2017-09-07 | 2018-03-06 | 重庆大学 | A kind of preparation method for aoxidizing viscose rayon crosslinking silkworm chrysalis peptide |
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| CN103061126A (en) * | 2012-12-28 | 2013-04-24 | 苏州市华智顾纺织有限公司 | Method for manufacturing flame retardant viscose fabric |
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