CN105860320B - Microcapsule flame retardant and preparation method thereof - Google Patents
Microcapsule flame retardant and preparation method thereof Download PDFInfo
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- CN105860320B CN105860320B CN201610213599.6A CN201610213599A CN105860320B CN 105860320 B CN105860320 B CN 105860320B CN 201610213599 A CN201610213599 A CN 201610213599A CN 105860320 B CN105860320 B CN 105860320B
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- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
- C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L27/04—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
- C08L27/06—Homopolymers or copolymers of vinyl chloride
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- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
- B01J13/02—Making microcapsules or microballoons
- B01J13/04—Making microcapsules or microballoons by physical processes, e.g. drying, spraying
- B01J13/043—Drying and spraying
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- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
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- C08L23/12—Polypropene
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- C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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- C08L2201/00—Properties
- C08L2201/02—Flame or fire retardant/resistant
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- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
- C08L2205/035—Polymer mixtures characterised by other features containing three or more polymers in a blend containing four or more polymers in a blend
Abstract
The invention discloses a microcapsule flame retardant, which comprises a capsule core and a capsule wall for coating the capsule core, wherein the capsule wall is made of resin, and the capsule core comprises: wood flour and an acid source, paraffin wax and surfactant adhered to the surface of the wood flour. The microcapsule flame retardant has good flame retardant and smoke suppression effects, and is low in toxic and harmful gas generation amount and good in compatibility with a polymer matrix. The invention also discloses a method for preparing the microcapsule flame retardant, which comprises the following steps: adding wood flour into an alkaline solution for boiling, and then filtering, washing and drying to obtain pretreated wood flour; adding the pretreated wood powder into an acid source for constant-temperature oscillation dipping, then carrying out suction filtration and drying, then grinding and mixing with emulsified paraffin, adding a surfactant for ultrasonic oscillation, and obtaining a capsule core; and (3) molding the capsule core and resin to obtain the microcapsule flame retardant.
Description
Technical Field
The invention relates to the technical field of polymer flame retardance, and particularly relates to a microcapsule flame retardant for a wood-plastic composite material and a preparation method thereof.
Background
The wood-plastic composite material is a novel composite material, wood powder or wood fiber is taken as a reinforcing material, and the matrix material is thermosetting or thermoplastic plastics such as polyethylene, polypropylene, polyvinyl chloride, ABS resin, polystyrene and the like. The wood-plastic composite material adopts wood processing residues (wood chips, wood shavings and the like) and waste plastics as production raw materials, integrates the advantages of wood and plastics, has the advantages of low price, convenience in molding, excellent performance, good dimensional stability, corrosion resistance, worm damage resistance, aging resistance, recyclability, and the like, is widely applied to the fields of buildings, ships, vehicles, furniture decoration and the like, and provides rich and colorful material choices for the home life of human beings. However, the wood-plastic composite materials have the disadvantages that the wood-plastic composite materials are flammable, the content of carbon and hydrogen elements in the materials is high, and a large amount of heat is generated during combustion, and meanwhile, a large amount of smoke and toxic gases are released.
In recent years, the occurrence of fire frequently occurs, and synthetic polymer materials are the main combustible substances in the fire. The data of the fire department in the department of public security shows that 38.8 thousands of fires are reported in 2013 all across the country, 2113 people die, 1637 people are injured, and the direct property loss is 48.5 million yuan. Compared with 2012, the number of the dead people is increased by 1.52 times, the number of the dead people is increased by 106%, the number of the injured people is increased by 1.85 times, and the direct property loss is increased by 122%. Among them, the house is burned, 11.7 thousands of which account for 30.1% of the total number, and 1215 people are killed, which account for 57.5% of the total number, and the larger fire is often occurred in the house and the commercial place, and the direct property loss is huge. In residential fires, more than 70% of fires are caused by the lack of fire resistance of plastic and wood materials, and in order to reduce the fire hazard, national standard GB20286-2006 requirements and marks on combustion performance of public place flame retardant products and components, from 7/1 of 2008, is enforced in China. According to the standard, common floor, furniture and home decoration materials cannot be used for decoration and fitment of public places. Therefore, it is very necessary to retard the flame of the frequently exposed home decoration materials such as wood-plastic composite floors.
At present, the flame retardant of the wood-plastic composite material mainly comprises halogen flame retardants, boron flame retardants, phosphorus flame retardants, aluminum magnesium compounds and the like. Although the halogen flame retardant has high flame retardant efficiency, a large amount of smoke and toxic and corrosive gas are generated in the material combustion process, so that the halogen flame retardant is not beneficial to the health of human beings and the environment; the phosphorus flame retardant is easy to dissolve in water, deliquescent and poor in compatibility with a matrix, and is easy to migrate and exude to the surface of a polymer in a high-temperature and high-humidity environment, so that the flame retardant performance and the mechanical performance of the material are reduced; the flame retardant such as the aluminum magnesium compound has good effect, but the addition amount is large, which brings adverse effect on the physical and mechanical properties of the polymer material. At present, the research on the flame retardant treatment of the wood-plastic composite material at home and abroad is still in the initial stage, based on the achievements and experiences of wood flame retardance and plastic flame retardance, the means of respectively retarding the wood powder or wood fiber and the matrix are generally adopted, the characteristics of the wood-plastic composite material are not noticed, the flame retardant effect is poor, and the cost performance is not high. Therefore, the flame retardant which is excellent in development performance and environment-friendly and is suitable for the wood-plastic composite material becomes an important subject for application and popularization of the wood-plastic composite material.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects in the prior art and providing an environment-friendly microcapsule flame retardant with high-efficiency flame retardant effect and good compatibility with a polymer matrix of a wood-plastic composite material and a preparation method thereof.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a microencapsulated flame retardant comprising a core and a wall encasing the core, the wall being a resin, the core comprising: wood flour and an acid source, paraffin wax and surfactant adhered to the surface of the wood flour. The flame retardant provided by the invention adopts a mode of integrating an acid source, a carbon source (wood powder) and a gas source (resin) into a whole and microencapsulating, so that the microcapsule flame retardant has the advantages of good flame retardant and smoke suppression effects, small generation amount of toxic and harmful gases, good compatibility with a polymer matrix and the like. The flame retardant material using the microcapsule flame retardant has good mechanical properties. The microencapsulation of the flame retardant can change the appearance and the state of the flame retardant, reduce the water solubility of the flame retardant, improve the thermal cracking temperature of the flame retardant, increase the compatibility of the flame retardant and a flame-retardant substrate, enhance the stability and the safety of the flame retardant and enhance the flame-retardant or smoke-suppression effect of the flame retardant. In addition, after the flame retardant is microencapsulated, the pungent smell of the flame retardant can be shielded, and the release of toxic components in the flame retardant in the material processing process is reduced, so that the microcapsule flame retardant is suitable for material processing with different requirements. After the resin is adopted for coating, the stability of the flame retardant is improved, the compatibility with a polymer matrix is good, the content of the flame retardant in the flame-retardant polymer is favorably improved, and the flame-retardant or smoke-suppression effect is enhanced.
The microcapsule flame retardant described above, preferably, the capsule core further comprises a smoke suppressant adhered to the surface of the wood flour. The smoke suppressant is added into the capsule core, so that the smoke suppression effect of the microcapsule flame retardant can be further improved.
As a general inventive concept, another aspect of the present invention provides a method for preparing the above microcapsule flame retardant, comprising the steps of:
(1) adding 80-120 parts by weight of wood flour into 200-400 parts by weight of alkaline solution for boiling, and then filtering, washing and drying to obtain pretreated wood flour;
(2) adding the pretreated wood powder obtained in the step (1) into 80-120 parts by weight of an acid source for constant-temperature oscillation dipping, then carrying out suction filtration and drying, then grinding and mixing with 2-10 parts by weight of emulsified paraffin, adding 1-5 parts by weight of a surfactant for ultrasonic oscillation, and obtaining capsule cores;
(3) and (3) taking 80-120 parts by weight of the capsule core obtained in the step (2) and 40-60 parts by weight of resin for molding, thus obtaining the microcapsule flame retardant.
Wood flour is used as a carbon source to carry the acid source. The wood powder has a large number of pipelines and gaps, can adsorb a large number of flame retardants and smoke suppressants, and the acid source is liquid solution and is converted into solid substances after being adsorbed and loaded by the wood powder, thereby being beneficial to subsequent forming operation. The paraffin is added to treat the wood powder, so that the polarity of the wood powder can be weakened, and the moisture absorption of the wood powder is reduced. The main components of the wood flour, namely cellulose and hemicellulose are carbohydrates, and can be used as a cheap carbon source in the intumescent flame retardant; the wood powder and the wood fiber are added into the wood-plastic composite material to reinforce the plastic, so that the density of the wood-plastic composite material can be reduced, the cost of the raw materials is reduced, and the addition amount of the wood powder in the wood-plastic composite material can be increased by coating the wood powder with the microcapsule, so that the comprehensive performance of the wood-plastic composite material is further improved.
In the preparation method, preferably, in the step (2), 10-30 parts by weight of smoke suppressant is further added to the acid source.
In the preparation method above, preferably, in the step (2), the acid source is one or more of pyrophosphoric acid, ammonium polyphosphate, phosphoric acid, nicotinic acid and isonicotinic acid; the surfactant is one or two of sodium dodecyl sulfate and sodium dodecyl benzene sulfonate; the smoke suppressant is one or two of stannic chloride or stannous chloride; in the step (3), the resin is one or two of melamine formaldehyde resin or epoxy resin. The acid source containing phosphorus and nitrogen elements is adopted, and the phosphorus and the nitrogen elements are important flame retardant elements and have mutual promotion effect, so that the flame retardance of the flame retardant can be increased, the dehydration and carbonization process of wood powder can be accelerated, and a compact foam carbon layer can be formed between the capsule core and the resin. Tin salts such as stannic chloride and stannous chloride are used as smoke suppressants. The flame-retardant material can be heated and decomposed to generate a large amount of toxic gas in a fire disaster, and the release of the toxic gas and the toxicity of smoke can be effectively reduced through the adsorption and catalytic conversion effects of the tin salt. When the melamine formaldehyde resin is used as the capsule wall material of the microcapsule, the microcapsule flame retardant has good compatibility with a polymer matrix in the wood-plastic composite material, so that the defect that wood powder with polar property and polymer material with non-polar property are incompatible in structure can be avoided, and the mechanical property of the wood-plastic composite material is strongly guaranteed. The mechanical property of the flame retardant after microencapsulation is better than that of the mixture molding of pure wood powder, flame retardant and polymer.
In the above preparation method, preferably, in the step (3), the molding process specifically includes: and mixing the capsule core with resin dissolved by an organic solvent, carrying out ultrasonic oscillation dispersion, adding a curing agent, stirring, heating, carrying out reflux reaction, filtering, washing and drying the material obtained after the reaction is finished, thus finishing the forming process of the microcapsule flame retardant.
In the above preparation method, preferably, in the step (3), the molding process specifically includes: putting the capsule core into a steam fog coating reaction tower, vibrating and dispersing to obtain capsule core particles, and mixing and coating the dispersed capsule core particles and resin steam fog sprayed from a resin nozzle; then, the coated material is cured and dried by air flow with the temperature of 80-120 ℃. The microcapsule flame retardant is formed by adopting the modes of steam fog coating and hot air flow curing and drying, the process is simple, the operation is simple and convenient, and the prepared microcapsule flame retardant has uniform particles, small particle size and no agglomeration.
In the above preparation method, preferably, in the step (1), the alkali solution is a sodium hydroxide or potassium hydroxide aqueous solution with a mass fraction of 0.1%; the boiling operation time is 1-3 h; the drying operation temperature is 105-115 ℃, and the drying time is 5-8 h. The alkali liquor can dissolve unsaponifiable matters, pectic substances and other micromolecular substances in the wood powder, and can also dissolve a small amount of lignin and hemicellulose, so that the impregnation liquid of the flame-retardant main agent in the subsequent process can be favorably permeated into pores of the wood powder, and the wood powder has a good loading effect on the impregnation liquid.
In the preparation method, preferably, in the step (2), the time of the constant-temperature oscillation dipping operation is 12-72 hours; the drying operation temperature is 105-115 ℃, and the drying time is 5-8 h; the time of ultrasonic oscillation operation is 1-2 h. After the surfactant is added, the wood powder can be prevented from agglomerating and coagulating by ultrasonic oscillation, and the coating microcapsule with small grain diameter is formed in the subsequent microcapsule forming process.
In the above preparation method, preferably, in the step (1), the wood flour has a mesh number of 80 to 120 meshes, and is obtained by cutting, crushing, ball-milling and sieving commercially available 40 to 60 meshes wood flour. The wood powder is fine, and the capsule is also fine; after ball milling and screening, the wood flour particles are uniform, and after shearing and ball milling, the agglomeration of the wood flour is obviously reduced.
Compared with the prior art, the invention has the following advantages:
(1) the invention adopts wood flour as a carbon source to load an acid source. The wood powder has a large number of pipelines and gaps, can adsorb a large number of flame retardants and smoke suppressants, and the acid source is liquid solution and is converted into solid substances after being adsorbed and loaded by the wood powder, so that the subsequent coating operation is facilitated; the main components of the wood flour, namely cellulose and hemicellulose are carbohydrates, and can be used as a cheap carbon source in the intumescent flame retardant; the wood powder and the wood fiber are added into the wood-plastic composite material to reinforce the plastic, so that the density of the wood-plastic composite material can be reduced, the cost of the raw materials is reduced, and the addition amount of the wood powder in the wood-plastic composite material can be increased by coating the wood powder with the microcapsule, so that the comprehensive performance of the wood-plastic composite material is further improved.
(2) The invention adopts one or more of pyrophosphoric acid, ammonium polyphosphate, phosphoric acid, nicotinic acid and isonicotinic acid as an acid source. P, N are important flame retardant elements and have mutual promoting effect, and the acid can accelerate the dehydration and carbonization process of wood powder to form a compact foam carbon layer with resin.
(3) The invention adopts tin salt such as stannic chloride, stannous chloride and the like as the smoke suppressant. The flame-retardant material can be heated and decomposed to generate a large amount of toxic gas in a fire disaster, and the release of the toxic gas and the toxicity of smoke can be effectively reduced through the adsorption and catalytic conversion effects of the tin salt.
(4) The invention adopts melamine formaldehyde resin as the capsule wall material of the microcapsule flame retardant. After the melamine formaldehyde resin is used as a capsule wall material to microencapsulate the flame retardant, the melamine formaldehyde resin has good compatibility with a polymer matrix in the wood-plastic composite material, can avoid the defect that wood powder with polar property and polymer material with non-polar property are incompatible in structure, and provides powerful guarantee for the mechanical property of the wood-plastic composite material. The mechanical property of the flame retardant after microencapsulation is better than that of the mixture molding of pure wood powder, flame retardant and polymer.
(5) The invention adopts the modes of steam fog coating and hot air flow curing drying in the reaction tower to form the microcapsule flame retardant, the process is simple, the operation is simple and convenient, and the prepared microcapsule flame retardant has uniform particles, small particle size and no agglomeration.
(6) According to the invention, through the optimized combination of the reaction raw materials and the combination of the corresponding coating process, the prepared microcapsule flame retardant has the characteristics of good expansion flame retardant effect, less smoke release amount, low smoke toxicity, high mechanical strength and the like when being applied to the wood-plastic composite material.
Drawings
FIG. 1 is a schematic view of the process of coating, curing and forming a bladder core by using a steam-fog coating reaction tower in the present invention.
Detailed Description
In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specified, the reagents and materials used in the present invention are commercially available products or products obtained by a known method.
Example 1
An embodiment of the microencapsulated flame retardant of the present invention and a method for preparing the same, wherein the preparation method comprises the following steps:
(1) cutting, crushing, ball-milling and screening 60-mesh commercially available wood flour to obtain 80-mesh wood flour, adding 100g of 80-mesh wood flour into 400g of 0.1% sodium hydroxide solution by mass fraction, boiling for 3 hours, filtering, washing and drying at 110 ℃ for 8 hours;
(2) adding the dried wood powder treated by the sodium hydroxide solution in the step (1) into 120g of 60% of pyrophosphate solution, carrying out constant-temperature oscillation and immersion for 12 hours, then carrying out suction filtration and drying at 105 ℃ for 8 hours; adding 8g of emulsified paraffin, grinding and mixing for 20 minutes, drying for 30 minutes at 105 ℃, adding 5g of sodium dodecyl benzene sulfonate, and ultrasonically oscillating for 2 hours to uniformly disperse to obtain a capsule core;
(3) 60g of melamine, 180g of 37% by mass aqueous formaldehyde solution and 400mL of distilled water were charged into a reactor, and 10% by weight of Na was used2CO3Adjusting the pH value of the solution adjusting system to be 8-9, then stirring and reacting at 70 ℃ for 1 hour to obtain a colorless and transparent prepolymer solution, cooling the solution, then adding 1.25g of resorcinol and 20mL of 5 wt% HCl, and stirring for 5 minutes to obtain melamine formaldehyde resin; as shown in fig. 1, 80g of the capsule core obtained in step (2) is put into a feeding section of a reaction tower, uniformly dispersed by a vibrating screen and then falls into an atomization coating section, 40g of the prepared melamine formaldehyde resin is sprayed and atomized by a nozzle and then coats the capsule core entering the atomization coating section, then the coated capsule core falling into the reaction curing section is cured and dried by air flow at 80-120 ℃, the dried particles are collected by cyclone and cooled in a cooling and collecting section at the bottom of the reaction tower, and the forming process of the microcapsule flame retardant is completed, so that the microcapsule flame retardant of the invention is obtained.
Mixing and stirring the microcapsule flame retardant prepared in the embodiment with polyvinyl chloride resin, calcium carbonate, medical stone, dioctyl phthalate, stearic acid and copolymer resin at high and low speeds, then kneading for the first time, extruding and kneading again, and finally open-milling and tabletting to obtain the PVC composite material, wherein the mass fractions of the components are as follows: 12% of microcapsule flame retardant, 30% of polyvinyl chloride resin, 35% of calcium carbonate, 5% of medical stone, 5% of dioctyl phthalate, 3% of stearic acid and 10% of copolymer resin EAV.
Example 2
An embodiment of the microencapsulated flame retardant of the present invention and a method for preparing the same, wherein the preparation method comprises the following steps:
(1) cutting, crushing, ball-milling and screening 60-mesh commercially available wood flour to obtain 80-mesh wood flour, adding 80g of 80-mesh wood flour into 400g of 0.1% sodium hydroxide solution by mass fraction, boiling for 3 hours, filtering, washing and drying at 110 ℃ for 5 hours;
(2) adding the dried wood powder treated by the sodium hydroxide solution in the step (1) into a composite solution consisting of 120g of phosphoric acid solution with the mass fraction of 30% and 10g of tin chloride, oscillating and soaking at constant temperature for 24 hours, then carrying out suction filtration and drying at 105 ℃ for 8 hours; adding 5g of emulsified paraffin, grinding and mixing for 30 minutes, drying for 20 minutes at 105 ℃, adding 3g of sodium dodecyl benzene sulfonate, and ultrasonically oscillating for 2 hours to uniformly disperse to obtain a capsule core;
(3) adding 80g of the capsule core obtained in the step (2) and 100mL of ethanol into a reactor, stirring for 5 minutes, then adding 50g E-44 epoxy resin dissolved by ethanol and acetone, carrying out ultrasonic oscillation to completely disperse, heating the dispersed solution to 50 ℃, dropwise adding a curing agent (polyamide resin or dicyandiamide) diluted by ethanol, keeping stirring and carrying out reflux reaction at 50 ℃ for 3 hours, carrying out suction filtration on the obtained material after the reaction is finished while the material is hot, then washing the material by ethanol and deionized water respectively, and carrying out vacuum drying at 60 ℃, thus completing the forming process of the microcapsule flame retardant, and obtaining the microcapsule flame retardant.
The microcapsule flame retardant prepared in the embodiment and E-44 epoxy resin (the mass ratio of the microcapsule flame retardant to the E-44 epoxy resin is 8:92) are mixed at high speed for 20 minutes at room temperature, then curing agent (polyamide resin or dicyandiamide) is added and mixed uniformly, and then the mixture is poured into a mold and cured for 24 hours at 35 ℃ in vacuum to obtain the flame-retardant epoxy resin.
Example 3
An embodiment of the microencapsulated flame retardant of the present invention and a method for preparing the same, wherein the preparation method comprises the following steps:
(1) cutting, crushing, ball-milling and screening 60-mesh commercially available wood flour to obtain 80-mesh wood flour, adding 120g of the 80-mesh wood flour into 400g of a 0.1% sodium hydroxide solution by mass fraction, boiling for 2 hours, filtering, washing and drying at 115 ℃ for 5 hours;
(2) adding the dried wood powder treated by the sodium hydroxide solution in the step (1) into a hot water solution (50-80 ℃) consisting of 400g of ammonium polyphosphate with the mass fraction of 30% and isonicotinic acid, oscillating and soaking at constant temperature for 36 hours, then carrying out suction filtration and drying at 105 ℃ for 8 hours; adding 8g of emulsified paraffin, grinding and mixing for 30 minutes, drying for 30 minutes at 105 ℃, adding 5g of sodium dodecyl benzene sulfonate, and ultrasonically oscillating for 2 hours to uniformly disperse to obtain a capsule core;
(3) 30g of melamine, 80g of an aqueous 37% formaldehyde solution and 150mL of distilled water were charged into a reactor, and 10% by weight of Na was used2CO3Adjusting the pH value of the solution adjusting system to be 8-9, then stirring and reacting at 70 ℃ for 1 hour to obtain a colorless and transparent prepolymer solution, cooling the solution, then adding 0.8g of resorcinol and 12mL of 5 wt% HCl, and stirring for 5 minutes to obtain melamine-formaldehyde resin; as shown in fig. 1, 120g of the capsule core obtained in the step (2) is put into a feeding section of a reaction tower, uniformly dispersed by a vibrating screen and then falls into an atomization coating section, 60g of the prepared melamine formaldehyde resin is sprayed and atomized by a nozzle and then coats the capsule core entering the atomization coating section, then the coated material falling into the reaction curing section is cured and dried by air flow at 80-120 ℃, the dried particles are collected by cyclone and cooled in a cooling and collecting section at the bottom of the reaction tower, and the forming process of the microcapsule flame retardant is completed, so that the microcapsule flame retardant is obtained.
The microcapsule flame retardant prepared in the embodiment is mixed with polypropylene (PP), dioctyl phthalate, stearic acid and paraffin at high and low speed, and then is milled and pressed to obtain a PP composite material, wherein the mass fractions of the components are as follows: 30% of microcapsule flame retardant, 55% of polypropylene (PP), 8% of dioctyl phthalate, 3% of stearic acid and 2% of paraffin.
Comparative example 1
Mixing and stirring polyvinyl chloride resin, calcium carbonate, medical stone, dioctyl phthalate, stearic acid and copolymer resin at high and low speeds, then kneading for the first time, extruding and kneading, and finally open-milling and tabletting to obtain the PVC composite material, wherein the mass fractions of the components are as follows: 42% of polyvinyl chloride resin, 35% of calcium carbonate, 5% of medical stone, 5% of dioctyl phthalate, 3% of stearic acid and 10% of copolymer resin EAV.
Comparative example 2
Mixing and stirring polyvinyl chloride resin, 80-mesh pyrophosphoric acid-loaded wood flour, calcium carbonate, medical stone, dioctyl phthalate, stearic acid and copolymer resin at high and low speeds, kneading for the first time, extruding and kneading, and finally open-milling and tabletting to obtain the PVC composite material, wherein the mass fractions of the components are as follows: 30% of polyvinyl chloride resin, 12% of wood powder loaded with pyrophosphoric acid, 35% of calcium carbonate, 5% of medical stone, 5% of dioctyl phthalate, 3% of stearic acid and 10% of copolymer resin EAV.
All the surfaces of the composite material samples prepared in the example 1 and the comparative examples 1-2 except the heated surface are wrapped by aluminum foil paper, and the aluminum foil paper is placed in a stainless steel sample frame to block heat transfer at the bottom of an aluminum foil. At 50kW/m2The samples were subjected to systematic study under thermal radiation to test their combustion performance, the experimental results are shown in table 1; the composite material samples prepared in example 1 and comparative examples 1-2 were cut into standard samples, and the tensile strength test was performed on a universal tester, and the impact strength test was performed on an impact tester. The experimental results are shown in table 2; the flame-retardant epoxy resin and the E-44 epoxy resin cured samples prepared in example 2 and the flame-retardant PP composite and PP resin samples prepared in example 3 were set at 35kW/m2The cone calorimetry was performed under the heat radiation of (1), and the results are shown in Table 3.
TABLE 1 Cone calorimetric parameter values of PVC composites obtained by different preparation processes
As can be seen from the data in table 1, the polyvinyl chloride resin composite panel having wood pyrophosphate powder supported thereon in comparative example 2 has increased flammability as compared to the polyvinyl chloride resin composite panel in comparative example 1. The added wood powder is loaded with pyrophosphoric acid, but the polyvinyl chloride resin composite board is still madeTotal caloric THR of 18.1MJ/m increase over comparative example 12The residue is reduced by 16.7%; but the addition of wood flour favors the reduction of carbon monoxide yield YCO and total smoke yield TSP. After the microcapsule of melamine formaldehyde resin coated pyrophosphoric acid treated wood flour is added into the polyvinyl chloride resin composite board (example 1), the PVC composite board of example 1 shows better flame retardant and smoke suppression effects than those of comparative example 1 and comparative example 2, and the heat release rate peak value PHRR of example 1 is respectively reduced by 116.3 and 93.2kW/m compared with comparative examples 1 and 22THR is only 63.6% of comparative example 1, 40% of comparative example 2; the carbon monoxide yield YCO and total smoke yield TSP decreased significantly and the residue increased. The acid source, the carbon source and the gas source integrated microcapsule flame retardant has excellent flame-retardant and smoke-suppressing effects.
TABLE 2 mechanical property parameter values of PVC composite materials obtained by different preparation processes
| Test specimen | Tensile strength (Mpa) | Impact Strength (kJ/m)2) | Elongation at Break (%) |
| Example 1 | 36.53 | 44.85 | 4.14 |
| Comparative example 1 | 37.23 | 47.06 | 4.30 |
| Comparative example 2 | 29.34 | 22.89 | 2.65 |
It can be seen from the data in table 2 that the addition of wood flour significantly reduces the mechanical properties of comparative example 2 compared to comparative example 1, and the mechanical properties of microcapsule flame retardant example 1 are greatly improved compared to comparative example 2, but slightly reduced compared to comparative example 1. It is demonstrated that the flame retardant of the present invention increases its compatibility with polymer matrices after microencapsulation.
TABLE 3 flame retardant epoxy resin (example 2), flame retardant PP composite (example 3) with E-44 epoxy resin, PP
Cone calorimetry parameter value of resin
As can be seen from the data in Table 3, the PHRR of the microencapsulated flame retardant E-44 epoxy resin (example 2) was greatly reduced by 541.5kW/m compared to E-442THR is reduced by 52%, TSP is 52.34m2/m2Reduced to 21.2m2/m2The residue increased by 34.9%. Also, the microencapsulated flame retardant flame-retarded PP resin (example 3) exhibited reduced heat release, reduced CO production and smoke release, and greatly increased residue after combustion, compared to PP resin.
In conclusion, when the microcapsule flame retardant prepared by the invention is used in PVC and PP composite materials and epoxy resin, the heat release and smoke generation of the materials during heating and burning can be effectively reduced, the flame retardant and smoke suppression effects are good, the compatibility of the microcapsule flame retardant and a material matrix is good, and the mechanical property of the flame-retardant material is slightly influenced.
Claims (5)
1. A preparation method of a microcapsule flame retardant for a wood-plastic composite material, wherein the microcapsule flame retardant comprises a capsule core and a capsule wall covering the capsule core, the capsule wall is made of resin, and the capsule core comprises: wood flour and an acid source, paraffin and a surfactant adhered to the surface of the wood flour;
the preparation method comprises the following steps:
(1) adding 80-120 parts by weight of wood flour into 200-400 parts by weight of alkaline solution for boiling, and then filtering, washing and drying to obtain pretreated wood flour; the grain number of the wood powder is 80-120 meshes, and the wood powder is obtained by cutting, crushing, ball-milling and screening the commercially available 40-60 meshes wood powder;
(2) adding the pretreated wood powder obtained in the step (1) into 80-120 parts by weight of an acid source for constant-temperature vibration impregnation, then performing suction filtration and drying, then grinding and mixing with 2-10 parts by weight of emulsified paraffin, adding 1-5 parts by weight of a surfactant for ultrasonic oscillation, and obtaining capsule cores; the acid source is one or more of pyrophosphoric acid, ammonium polyphosphate, phosphoric acid, nicotinic acid and isonicotinic acid;
(3) taking 80-120 parts by weight of the capsule core obtained in the step (2) and 40-60 parts by weight of resin for molding to obtain the microcapsule flame retardant; the resin is one or two of melamine formaldehyde resin or epoxy resin;
in the step (3), the forming process specifically includes: putting the capsule core into a steam fog coating reaction tower, vibrating and dispersing to obtain capsule core particles, and mixing and coating the dispersed capsule core particles and resin steam fog sprayed from a resin nozzle; then, the coated material is cured and dried by air flow with the temperature of 80-120 ℃.
2. The method of claim 1, wherein: in the step (2), 10-30 parts by weight of smoke suppressant is added into the acid source.
3. The method of claim 2, wherein: the surfactant is one or two of sodium dodecyl sulfate and sodium dodecyl benzene sulfonate; the smoke suppressant is one or two of stannic chloride or stannous chloride.
4. The method of claim 1, wherein: in the step (1), the alkali solution is a sodium hydroxide or potassium hydroxide aqueous solution with the mass fraction of 0.1%; the boiling operation time is 1-3 h; the drying operation temperature is 105-115 ℃, and the drying time is 5-8 h.
5. The method of claim 1, wherein: in the step (2), the time of constant-temperature oscillation dipping operation is 12-72 h; the drying operation temperature is 105-115 ℃, and the drying time is 5-8 h; the time of ultrasonic oscillation operation is 1-2 h.
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| CN106543480B (en) * | 2016-11-01 | 2019-02-01 | 中南林业科技大学 | A kind of sulfonation cross linked ciclodextrines starch capsules anti-flaming smoke-inhibiting agent and preparation method thereof |
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| CN108905038B (en) * | 2018-08-27 | 2020-07-03 | 安徽理工大学 | Micro-capsule fire extinguishing agent based on secondary shock wave throwing and preparation method thereof |
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