Silicon-containing high-transparency flame-retardant EVA light conversion film and preparation method thereof
阅读说明：本技术 一种含硅高透明阻燃eva转光膜及其制备方法 (Silicon-containing high-transparency flame-retardant EVA light conversion film and preparation method thereof ) 是由 丁寅 胡子涛 于 2020-06-29 设计创作，主要内容包括：本发明涉及一种接枝POSS的高透明阻燃乙烯-醋酸乙烯酯(EVA)转光膜及其制法,它是首先合成七聚环戊基倍半硅氧烷三硅醇,然后合成烯丙基倍半硅氧烷,将其与EVA在加入BPO(过氧化二苯甲酰)的条件下反应得到EVA-g-T8(一种POSS)接枝聚合物,将其与转光剂共混,制备出接枝POSS的阻燃EVA转光膜。本发明制备的阻燃EVA转光膜透光率可达93.5％,通过UL94 V-0等级测试,极限氧指数高达38.2％,荧光强度相较于直接掺杂POSS的EVA膜增强了28.5％,燃烧测试过程中几乎无滴落现象。(The invention relates to a high transparent flame retardant ethylene-vinyl acetate (EVA) light conversion film grafted with POSS and a preparation method thereof, which comprises the steps of firstly synthesizing hepta-cyclopentyl silsesquioxane trisilicon alcohol, then synthesizing allyl silsesquioxane, reacting the allyl silsesquioxane with EVA under the condition of adding BPO (dibenzoyl peroxide) to obtain EVA-g-T8 (a POSS) graft polymer, and blending the EVA graft polymer with a light conversion agent to prepare the flame retardant EVA light conversion film grafted with POSS. The light transmittance of the flame-retardant EVA light conversion film prepared by the invention can reach 93.5%, the limit oxygen index can reach 38.2% through UL 94V-0 grade test, the fluorescence intensity is enhanced by 28.5% compared with that of an EVA film directly doped with POSS, and the flame-retardant EVA light conversion film hardly has a dripping phenomenon in the combustion test process.)
1. The utility model provides a high transparent fire-retardant EVA membrane that turns round, characterized by: the high-transparency flame-retardant EVA light conversion film is prepared by blending an ethylene-vinyl acetate grafted allyl silsesquioxane T8 polymer EVA-g-T8 grafted polymer and a light conversion agent through a solution grafting method.
2. The preparation method of the high-transparency flame-retardant EVA light conversion film is characterized by comprising the following steps of:
step 1, adding acetone into a three-neck flask, adding cyclopentyl trichlorosilane, dropwise adding distilled water into the three-neck flask at a speed of 30-50 drops per minute by using a dropping funnel, stirring vigorously, heating and refluxing after the dropwise adding of the distilled water is finished, reacting for 48-72 hours, vacuumizing and filtering a product after the reaction is finished, cleaning the product by using acetone, dissolving the product in pyridine after drying, filtering out insoluble substances, pouring the filtrate into frozen concentrated hydrochloric acid, filtering, and drying at 40-60 ℃ to obtain hepta-cyclopentyl silsesquioxane trisilicitol;
step 2, dispersing heptapoly-cyclopentyl silsesquioxane trisilicitol obtained in the step 1 into THF, adding the dispersed heptapoly-cyclopentyl silsesquioxane trisilicitol into a flask, adding triethylamine, fully stirring and uniformly mixing, dropwise adding allyl trichlorosilane, filtering out precipitates after violently stirring for 3-5 h, carrying out the whole reaction in an ice water bath, concentrating a transparent filtrate from which the precipitates are filtered out, putting the transparent filtrate into a large amount of anhydrous ethanol, precipitating the product in a white particle form, drying and weighing to obtain a product, namely, allyl silsesquioxane T8;
step 3, adding EVA, allyl silsesquioxane T8 and benzoyl peroxide BPO into a flask, performing nitrogen protection, adding toluene subjected to reflux condensation treatment at one time by using an injector, placing a reaction bottle into an oil bath, heating to 50-70 ℃, stirring for 15-25 min under the protection of nitrogen until the added raw materials are gradually dissolved, slowly raising the temperature to 80-100 ℃, dropwise adding the reaction liquid into ice methanol after 6-8 h, stirring to generate light yellow flocculent precipitate after the reaction is finished, repeatedly washing the product obtained by suction filtration for 2-4 times by using methanol, and performing vacuum drying for 12-36 h at 75-100 ℃ to obtain a crude product EVA-g-T8 graft polymer;
step 4, putting the dried EVA-g-T8 graft polymer into a flask, adding toluene, heating and refluxing to dissolve the EVA, then performing suction filtration to remove insoluble substances (mainly EVA cross-linked products), dripping the filtrate into a large amount of petroleum ether to generate white flocculent precipitates, well dissolving T8 and homopolymers thereof in the petroleum ether to remove the white flocculent precipitates, and drying the precipitates obtained by filtration in a vacuum drying oven at the temperature of 40-60 ℃ for 12-30 h to obtain the refined EVA-g-T8 graft polymer;
and 5, carrying out double-roller open mixing on the EVA-g-T8 graft polymer and the light conversion agent by a plasticator according to a proportion, wherein the mixing temperature is cold roller room temperature, the mixing time is 3-5 min, and carrying out compression molding on the mixed material in a flat-plate vulcanizing machine.
3. The method for preparing the highly transparent flame-retardant EVA light conversion film according to claim 2, wherein the method comprises the following steps: the molar ratio of the materials in the step 2 is heptapoly-cyclopentylsilsesquioxane trisilicol, allyl trichlorosilane and triethylamine which are 1: 1-1.06: 8.3-10.2.
4. The method for preparing the highly transparent flame-retardant EVA light conversion film according to claim 2, wherein the method comprises the following steps: in the step 3, the EVA is an ethylene-vinyl acetate copolymer with the VA content of 10-40 wt%.
5. The method for preparing the highly transparent flame-retardant EVA light conversion film according to claim 2, wherein the method comprises the following steps: in the step 3, the mass ratio of VA to T8 in the EVA is 1: 2-10, and the mass ratio of T8 to BPO is 1: 20.
6. The method for preparing the highly transparent flame-retardant EVA light conversion film according to claim 2, wherein the method comprises the following steps: the light conversion agent in the step 5 is Eu (TTA)3Dpbt、Eu(SA)3phen or Eu (DBM)3phen。
7. The highly transparent flame retardant EVA light conversion film of claim 6The preparation method is characterized in that: eu (TTA)3The dpbt has better excitation in the ultraviolet region of 200-400 nm, Eu (SA)3phen has better excitation in the ultraviolet region of 300-330 nm, Eu (DBM)3phen has better excitation in an ultraviolet region of 250-400 nm, wherein TTA is α -thienyl formyl trifluoroacetone, SA is salicylic acid, phen is phenanthroline, DBM is dibenzoyl methane, and dpbt is 2- (N, N-diethylaniline-4-yl) -4, 6-bis (3, 5-dimethylpyrazol-1-yl) -1, 3, 5-triazine.
8. The method for preparing the highly transparent flame-retardant EVA light conversion film according to claim 2, wherein the method comprises the following steps: the mass fraction of the light conversion agent in the step 5 is 0.5-3%.
Technical Field
The invention belongs to the field of flame-retardant high polymer materials, and particularly relates to a POSS (polyhedral oligomeric silsesquioxane) -grafted flame-retardant EVA material and application thereof in a light conversion film.
Background
EVA is ethylene-vinyl acetate copolymer, can be obtained by copolymerization of ethylene and vinyl acetate, is a general high molecular polymer, and has a molecular formula of (C)2H4)x.(C4H6O2)yThe material has the advantages of high light transmittance, good flexibility, low melting temperature, good melt fluidity, strong bonding performance and the like, and is the most widely applied solar cell packaging material at present. However, EVA itself is extremely flammable, has a limiting oxygen index of only about 18%, and generates a large amount of molten droplets when burned, which greatly limits further applications of EVA.
At present, people have developed a certain research aiming at the problem of EVA flame retardance, and most of the EVA flame retardants commonly used in the early stage are halogen flame retardants, such as Shenshu (Shenshu, a dawsonite compounded zinc fluoborate flame-retardant EVA cable material and a preparation method thereof [ P ]. Chuzhou: CN106243477A, 2016-12-21.) the method of compounding dawsonite with zinc fluoborate is adopted to prepare the flame-retardant EVA cable material, although the flame-retardant EVA cable material can obtain obvious flame-retardant effect, a large amount of toxic gas which is not beneficial to environmental protection can be released in the combustion process, so that the flame-retardant EVA cable material is gradually replaced by the halogen-free flame retardant.
The rubber sheath material is prepared by using more inorganic nano flame retardants such as magnesium hydroxide and aluminum hydroxide, wherein EVA resin is used as a main body, magnesium hydroxide is used as a flame retardant to prepare the rubber sheath material, and the ratio of EVA to magnesium hydroxide is 1: 1.1-1.3 (Xuyayuan, Chenming, Qin Jianwei, Deng Najun, Huang Chao. low smoke halogen-free flame retardant EVA rubber sheath material for mining cables and a preparation method thereof [ P ]. tin-free: CN108102206A, 2018-06-01 ]); the major rock and the like adopt a series of inorganic flame retardants of magnesium hydroxide, aluminum hydroxide, hydrotalcite, magnesium sulfate whisker and calcium sulfate whisker to prepare the ceramifiable EVA cable material with obvious flame retardant and smoke suppression effects (tremiengshi, heyday, Yangshan, Gangjing, a ceramifiable EVA halogen-free flame retardant cable material and a preparation method thereof [ P ]. Tianjin: CN108164805A, 2018-06-15.). These inorganic flame retardants have a certain effect, but the flame retardant effect is only obvious when the addition amount is very large, which affects the properties of the EVA material itself, especially the transparency.
The phosphorus-nitrogen flame retardant is also a widely used halogen-free flame retardant, and the ursolic acid and the like mainly take lignin, aldehyde, melamine, alkali, aluminum salt, red phosphorus and a dispersing agent as raw materials, and the melamine modified lignin/aluminum hydroxide double-coated red phosphorus flame retardant is prepared by combining a Mannich reaction and a chemical coprecipitation method, and has good flame retardant and smoke suppression effects when being applied to EVA resin (the ursolic acid is a melamine modified lignin/aluminum hydroxide double-coated red phosphorus flame retardant and the application thereof in the EVA resin [ P ]. Fuzhou: CN109054100A, 2018-12-21.); wujiandong and the like design a halogen-free flame retardant consisting of ammonium polyphosphate, pentaerythritol, melamine and red phosphorus and are used for preparing an EVA hot melt adhesive film for wall cloth (Wujiandong, Cai Yunmei, Yangyan, Zhanlin, a halogen-free flame retardant EVA hot melt adhesive film for wall cloth and a preparation method thereof [ P ]. Fushan: CN108893068A, 2018-11-27.). Among the flame retardants, unsafe factors exist in the storage and combustion processes of red phosphorus, the heat stability of phosphorus-nitrogen flame retardants such as ammonium polyphosphate and melamine is not enough, foaming, flame retardant decomposition and other phenomena are easily generated during processing and injection molding, and the problem of mold corrosion also exists.
The silicon flame retardant is a commonly used environment-friendly flame retardant, the most commonly used silicon flame retardant is polysiloxane and silicate, the polysiloxane has good reaction activity and substrate compatibility, and can be connected with a large number of active functional groups, such as double bonds, epoxy groups, amino groups and the like, so that the silicon flame retardant not only can generate self-polymerization, but also can be connected into a material polymer chain through the active functional groups, and thus, the silicon flame retardant endows the material with new properties. The halogen-free flame-retardant composite material prepared by selecting silane coupling agent KH-792, nitrogen-containing silicon-boron halogen-free flame retardant NBSi synthesized by boric acid and phosphorus-containing flame retardant DOPO to compound with the synergistic flame-retardant PP/EVA composite material has better mechanical, processing, flame-retardant and thermal stability, but still belongs to an additive flame retardant, and the DOPO addition amount is very high (Xiayin, Ninglong, Zhangyue. preparation method of the nitrogen-containing silicon-boron halogen-free flame retardant and DOPO synergistic flame-retardant PP/EVA composite material [ P ]. Dalian: CN106543562A, 2017-03-29.).
Therefore, an experimental scheme for grafting the silicon-containing compound molecule to the EVA is tried to be designed, so that the flame retardant property of the EVA is fundamentally improved, and the light conversion property of the EVA light conversion film is basically not influenced.
Disclosure of Invention
Aiming at the problems, the invention utilizes the silicon halogen-free flame retardant and the EVA grafting, can obviously improve the comprehensive mechanical property and the flame retardant property of the EVA, and meets the application requirement of the specific field of flame retardance.
The invention aims to solve the problems and provides a simple, convenient and flexible method which is environment-friendly and has good flame retardant effect and does not influence the light transmittance of an EVA light conversion film.
To achieve the aim, the invention firstly prepares heptapoly-cyclopentylsilsesquioxane trisilicol (T7) by refluxing and hydrolyzing cyclopentyltrichlorosilane in acetone, and synthesizes allyl silsesquioxane by a vertex-angle capping method through T7 and allyl trichlorosilane (the preparation process is shown as formula 1).
The EVA and allylsilsesquioxane were then reacted with the addition of BPO (dibenzoyl peroxide) to give the crude EVA-g-T8 graft polymer (see formula 2 for preparation).
Refining EVA-g-T8 graft polymer, mixing with light conversion agent by a plasticator, and molding by a press vulcanizer.
The technical scheme adopted by the invention comprises the following specific steps:
a high-transparency flame-retardant EVA light conversion film is prepared by blending an ethylene-vinyl acetate grafted allyl silsesquioxane T8 polymer EVA-g-T8, a grafted polymer EVA-g-T8 and a light conversion agent through a solution grafting method.
The preparation method of the high-transparency flame-retardant EVA light conversion film comprises the following steps:
step 1, adding acetone into a three-neck flask, adding cyclopentyl trichlorosilane, dropwise adding distilled water into the three-neck flask at a speed of 30-50 drops per minute by using a dropping funnel, stirring vigorously, heating and refluxing after the dropwise adding of the distilled water is finished, reacting for 48-72 hours, vacuumizing and filtering a product after the reaction is finished, cleaning the product by using acetone, dissolving the product in pyridine after drying, filtering out insoluble substances, pouring the filtrate into frozen concentrated hydrochloric acid, filtering, and drying at 40-60 ℃ to obtain hepta-cyclopentyl silsesquioxane trisilicitol;
step 2, dispersing heptapoly-cyclopentyl silsesquioxane trisilicitol obtained in the step 1 into THF, adding the dispersed heptapoly-cyclopentyl silsesquioxane trisilicitol into a flask, adding triethylamine, fully stirring and uniformly mixing, dropwise adding allyl trichlorosilane, filtering out precipitates after violently stirring for 3-5 h, carrying out the whole reaction in an ice water bath, concentrating a transparent filtrate from which the precipitates are filtered out, putting the transparent filtrate into a large amount of anhydrous ethanol, precipitating the product in a white particle form, drying and weighing to obtain a product, namely, allyl silsesquioxane T8;
step 3, adding EVA, allyl silsesquioxane T8 and benzoyl peroxide BPO into a flask, performing nitrogen protection, adding toluene subjected to reflux condensation treatment at one time by using an injector, placing a reaction bottle into an oil bath, heating to 50-70 ℃, stirring for 15-25 min under the protection of nitrogen until the added raw materials are gradually dissolved, slowly raising the temperature to 80-100 ℃, dropwise adding the reaction liquid into ice methanol after 6-8 h, stirring to generate light yellow flocculent precipitate after the reaction is finished, repeatedly washing the product obtained by suction filtration for 2-4 times by using methanol, and performing vacuum drying for 12-36 h at 75-100 ℃ to obtain a crude product EVA-g-T8 graft polymer;
step 4, putting the dried EVA-g-T8 graft polymer into a flask, adding toluene, heating and refluxing to dissolve the EVA, then performing suction filtration to remove insoluble substances (mainly EVA cross-linked products), dripping the filtrate into a large amount of petroleum ether to generate white flocculent precipitates, well dissolving T8 and homopolymers thereof in the petroleum ether to remove the white flocculent precipitates, and drying the precipitates obtained by filtration in a vacuum drying oven at the temperature of 40-60 ℃ for 12-30 h to obtain the refined EVA-g-T8 graft polymer;
and 5, carrying out double-roller open mixing on the EVA-g-T8 graft polymer and the light conversion agent by a plasticator according to a proportion, wherein the mixing temperature is cold roller room temperature, the mixing time is 3-5 min, and carrying out compression molding on the mixed material in a flat-plate vulcanizing machine.
According to the preparation method of the high-transparency flame-retardant EVA light conversion film, the molar ratio of the materials in the step 2 is heptapoly-cyclopentylsilsesquioxane trisilicol, allyl trichlorosilane and triethylamine is 1: 1-1.06: 8.3-10.2.
In the preparation method of the high-transparency flame-retardant EVA light conversion film, in the step 3, the EVA is an ethylene-vinyl acetate copolymer with the VA content of 10-40 wt%.
According to the preparation method of the high-transparency flame-retardant EVA light conversion film, in the step 3, the mass ratio of VA to T8 in EVA is 1: 2-10, and the mass ratio of T8 to BPO is 1: 20.
In the preparation method of the high-transparency flame-retardant EVA light conversion film, benzoyl peroxide BPO is used as an initiator in the reaction of the step 3, and double bonds are opened by allyl silsesquioxane under the action of free radicals decomposed by the initiator to combine with main chain free radicals losing H in an EVA structure to generate a grafting reaction.
In the preparation method of the highly transparent flame-retardant EVA light conversion film, the light conversion agent in the step 5 is one of a series of rare earth organic complexes, such as Eu (TTA)3Dpbt、Eu(SA)3phen、Eu(DBM)3phen, and the like.
In the preparation method of the high-transparency flame-retardant EVA light conversion film, the mass fraction of the light conversion agent in the step 5 is 0.5-3%.
According to the preparation method of the high-transparency flame-retardant EVA light conversion film, in the step 5, a proper mold is selected according to relevant standards, a mixed material sample is poured into the mold, when the temperature of a flat vulcanizing machine rises to 150-200 ℃, the mold is placed into the flat vulcanizing machine, hot pressing is carried out for 400-600 s under 10-15 MPa, then cold pressing is carried out for 300-500 s, a sample slice is prepared, and the slice is cut into sample strips required by testing on a pneumatic slicer by using a standard size cutter so as to be used for testing various performances.
Compared with the prior art, the invention has the beneficial effects that:
the invention utilizes the advantages of low toxicity, high flame retardance, high efficiency, molten drop inhibition and smoke inhibition of the silicon flame retardant to improve the flame retardance of the EVA adhesive film. The invention synthesizes the allyl silsesquioxane by using a vertex angle-cap method, successfully connects the allyl silsesquioxane on an EVA molecular chain by using a solution grafting method, improves the flame retardant property of EVA in a level manner, and provides a method which is environment-friendly, has good flame retardant effect and does not influence the light transmittance of an EVA light conversion film.
Detailed Description
The present invention will be described in detail with reference to examples.