阅读说明：本技术 一种聚偏氟乙烯塑料的回收处理方法 (Method for recycling polyvinylidene fluoride plastic ) 是由 许亮亮 于 2019-09-03 设计创作，主要内容包括：本发明涉及新型功能材料技术领域,公开了一种聚偏氟乙烯塑料的回收处理方法,将制备得到的复合添加剂与粉碎后的聚偏氟乙烯废旧塑料粒子混合,加入偶联剂,通过双螺杆挤出机挤出造粒,制备得到的复合添加剂在与聚偏氟乙烯废旧塑料熔融共混时,相容性好,提高了结构的致密性和均一性,所述复合添加剂为多金属有机化合物结构,在与聚偏氟乙烯结合时,结晶面积减少,能够抑制光氧化反应的发生,提高拉伸强度和耐高温性的同时,也提高了聚偏氟乙烯分子的耐光、耐低温性以及热稳定性,克服了废旧聚偏氟乙烯塑料严重老化,使得制备得到的塑料产品性能降低的问题,消除了因添加填料而引起的表面缺陷等质量问题,改善了材料耐低温性和柔韧性。(The invention relates to the technical field of novel functional materials, and discloses a method for recycling polyvinylidene fluoride plastic, which comprises the steps of mixing a prepared composite additive with crushed polyvinylidene fluoride waste plastic particles, adding a coupling agent, extruding and granulating by a double-screw extruder, wherein the prepared composite additive has good compatibility and improved structural compactness and uniformity when being fused and blended with the polyvinylidene fluoride waste plastic, the composite additive is a multi-metal organic compound structure, when being combined with the polyvinylidene fluoride, the crystallization area is reduced, the occurrence of photo-oxidation reaction can be inhibited, the tensile strength and high temperature resistance are improved, simultaneously the light resistance, low temperature resistance and thermal stability of polyvinylidene fluoride molecules are also improved, the problems of serious aging of the waste polyvinylidene fluoride plastic and reduction of the performance of the prepared plastic product are solved, the quality problems of surface defects and the like caused by adding the filler are eliminated, and the low temperature resistance and the flexibility of the material are improved.)

1. A method for recycling polyvinylidene fluoride plastic is characterized in that waste polyvinylidene fluoride plastic is placed into a crusher to be crushed into small particles with the particle size of 1-3 mm after impurity removal, prepared composite additive is added, the obtained composite additive is placed into a high-speed mixer to be blended, the premixed material is placed into a drying oven with the temperature of 110-115 ℃ after mixing, the drying oven is dried for 4-6 hours, then the obtained premixed material is sent into a double-screw extruder, coupling agent is added, the obtained particles are jointly extruded and granulated, and the obtained granules are further processed into various polyvinylidene fluoride plastic products, wherein the preparation method of the composite additive comprises the following steps:

(1) Weighing 18-20 g of sodium silicate, adding into a beaker, adding 80-90 ml of sodium hydroxide aqueous solution into the beaker, stirring and dissolving, weighing 0.25-0.30 mmol of cobalt chloride hexahydrate, placing into the beaker, and continuously stirring for 20-30 minutes;

(2) Weighing 0.15-0.18 mmol of europium oxide, placing in a beaker, adding 45-50 ml of hydrochloric acid solution, heating to 55-60 ℃, and stirring for dissolving;

(3) Adding the dissolving solution prepared in the step (2) into the beaker in the step (1) under stirring, mixing, adding 20-30 ml of deionized water and 10-12 ml of N, N-dimethylformamide, ultrasonically dispersing for 15-20 minutes, sealing by using a sealing film, standing for 10-12 hours in an oven at 85-90 ℃ to obtain a solid precipitate, filtering the precipitate, cleaning for 3-4 times by using distilled water, drying for 8-10 hours in an oven at 50-60 ℃, placing the obtained dried product into a quartz boat, placing into a preheated tubular furnace, heating to 560-570 ℃, preserving the heat for 80-90 minutes, naturally cooling to room temperature, and grinding into fine powder to obtain the composite additive.

2. The recycling method of polyvinylidene fluoride plastic according to claim 1, wherein the addition amount of the composite additive is 0.11-0.12% of the mass of the waste polyvinylidene fluoride plastic.

3. The recycling method of polyvinylidene fluoride plastic according to claim 1, wherein the coupling agent is added in an amount of 14-18% by mass of the composite additive.

4. The recycling method of polyvinylidene fluoride plastic according to claim 1, wherein the coupling agent is vinyltriethoxysilane.

5. The recycling method of polyvinylidene fluoride plastic according to claim 1, wherein the mass concentration of the sodium hydroxide aqueous solution in the step (1) is 22-24%.

6. The recycling method of polyvinylidene fluoride plastic according to claim 1, wherein the hydrochloric acid solution in the step (2) has a molar concentration of 3.5-4.0 mol/l.

7. The recycling method of polyvinylidene fluoride plastic according to claim 1, wherein the temperature of the tubular furnace after preheating in step (3) is 270-280 ℃.

8. The recycling method of polyvinylidene fluoride plastic according to claim 1, wherein the particle size of the composite additive in step (3) is 10-20 μm.

Technical Field

The invention belongs to the technical field of novel functional materials, and particularly relates to a method for recycling polyvinylidene fluoride plastic.

background

Polyvinylidene fluoride (PVDF) is a semi-crystalline polymer in normal state and has a crystallinity of about 50%. There are 5 crystal forms, such as alpha, beta, gamma, delta and epsilon, which are formed under different conditions and can be mutually transformed under certain conditions (action of heat, electric field, mechanical and radiation energy). Of these 5 crystal forms, the beta crystal form is the most important, and PVDF used for piezoelectric and pyroelectric applications mainly contains the beta crystal form. White powdery crystalline polymer having a density of 1.75 to 1.78g/cm 3. The glass transition temperature is-39 ℃, the brittle temperature is-62 ℃, the melting point is 170 ℃, the thermal decomposition temperature is about 350 ℃, and the long-term use temperature is-40-150 ℃. Can be formed by common thermoplastic processing method. Its outstanding features are high mechanical strength and high radiation resistance. Has good chemical stability, is not corroded by acid, alkali, strong oxidant and halogen at room temperature, is the second-ranked large product with the output in the prior fluorine-containing plastics, and has the annual capacity of more than 4.3 ten thousand tons in the whole world.

along with the gradual increase of the demand of polyvinylidene fluoride plastics, a large amount of waste polyvinylidene fluoride plastics are indispensably generated, the price of polyvinylidene fluoride is relatively high, and along with the stronger understanding of people on environmental protection, the recycling of waste plastics becomes a new industry; the existing method mainly improves the performance of the regenerated plastic by increasing the ratio of new materials of the plastic and adding a cross-linking agent, a filler and the like, but the performance is not obviously improved, and simultaneously, new resource consumption is caused, so that the problem of low recycling rate is caused.

disclosure of Invention

The invention aims to solve the problems in the prior art and provides a method for recycling polyvinylidene fluoride plastic, which can inhibit the occurrence of photo-oxidation reaction, improve the tensile strength and high temperature resistance, and improve the light resistance, low temperature resistance and thermal stability of polyvinylidene fluoride molecules.

The invention is realized by the following technical scheme:

A method for recycling polyvinylidene fluoride plastics comprises the steps of removing impurities from waste polyvinylidene fluoride plastics, then putting the waste polyvinylidene fluoride plastics into a crusher to be crushed into small particles with the particle size of 1-3 mm, adding a prepared composite additive, putting the mixture into a high-speed mixer to be blended, putting a premix into a drying oven with the temperature of 110-115 ℃ after mixing, drying the premix for 4-6 hours, then sending the premix into a double-screw extruder, adding a coupling agent, jointly extruding and granulating, and further processing the obtained granules into various polyvinylidene fluoride plastic products, wherein the preparation method of the composite additive comprises the following steps:

(1) weighing 18-20 g of sodium silicate, adding into a beaker, adding 80-90 ml of sodium hydroxide aqueous solution into the beaker, stirring and dissolving, weighing 0.25-0.30 mmol of cobalt chloride hexahydrate, placing into the beaker, and continuously stirring for 20-30 minutes;

(2) Weighing 0.15-0.18 mmol of europium oxide, placing in a beaker, adding 45-50 ml of hydrochloric acid solution, heating to 55-60 ℃, and stirring for dissolving;

(3) Adding the dissolving solution prepared in the step (2) into the beaker in the step (1) under stirring, mixing, adding 20-30 ml of deionized water and 10-12 ml of N, N-dimethylformamide, ultrasonically dispersing for 15-20 minutes, sealing by using a sealing film, standing for 10-12 hours in an oven at 85-90 ℃ to obtain a solid precipitate, filtering the precipitate, cleaning for 3-4 times by using distilled water, drying for 8-10 hours in an oven at 50-60 ℃, placing the obtained dried product into a quartz boat, placing into a preheated tubular furnace, heating to 560-570 ℃, preserving the heat for 80-90 minutes, naturally cooling to room temperature, and grinding into fine powder to obtain the composite additive.

As further description of the scheme, the addition amount of the composite additive is 0.11-0.12% of the mass of the waste polyvinylidene fluoride plastic.

As a further description of the above scheme, the addition amount of the coupling agent is 14-18% of the mass of the composite additive.

As a further description of the above scheme, the coupling agent is vinyltriethoxysilane.

as a further description of the above scheme, the mass concentration of the sodium hydroxide aqueous solution in the step (1) is 22-24%.

As a further description of the above scheme, the hydrochloric acid solution of the step (2) has a molar concentration of 3.5 to 4.0 mol/L.

as a further description of the above scheme, the temperature of the tubular furnace after preheating in step (3) is 270-.

As a further description of the above scheme, the particle size of the composite additive in step (3) is between 10 and 20 microns.

Compared with the prior art, the invention has the following advantages: in order to solve the problem of poor recycling rate of waste polyvinylidene fluoride plastics after performance decay in the prior art, the invention provides a method for recycling polyvinylidene fluoride plastics, which comprises the steps of mixing a prepared composite additive with crushed waste polyvinylidene fluoride plastic particles, adding a coupling agent, extruding and granulating by a double-screw extruder, wherein the prepared composite additive has good compatibility and improved structural compactness and uniformity when being melted and blended with the waste polyvinylidene fluoride plastic, the composite additive is a multi-metal organic compound structure, when being combined with the polyvinylidene fluoride, the crystallization area is reduced, the occurrence of photo-oxidation reaction can be inhibited, the tensile strength and the high temperature resistance are improved, simultaneously, the light resistance, the low temperature resistance and the thermal stability of polyvinylidene fluoride molecules are improved, and the advantage complementation among materials is realized, the comprehensive performance of the composite modified material is improved, the problem that the performance of the prepared plastic product is reduced due to the severe aging of the waste polyvinylidene fluoride plastic is solved, the quality problems such as surface defects and the like caused by the addition of fillers are solved, the service life of the regenerated polyvinylidene fluoride plastic is obviously prolonged, the mechanical properties such as tensile strength, impact strength, bending strength and the like of the plastic are improved, the low temperature resistance and flexibility of the material are improved, the extrusion rate is improved, defective products are reduced, the modification operation steps are simple, the cost is obviously reduced, and the appearance and the physical and mechanical properties of the plastic product are ensured for a long time. The improvement on the toughness and the strength of the polyvinylidene fluoride recycled plastic is considered, the utilization value of the waste polyvinylidene fluoride plastic is improved, the harm of the waste plastic to the environment is reduced, the practical significance of prolonging the service life of the recycled polyvinylidene fluoride plastic and expanding the application field of the recycled polyvinylidene fluoride plastic can be realized, and the method is a technical scheme which is very worthy of popularization and application.

Detailed Description

In order to make the objects, technical solutions and effects of the present invention clearer and clearer, the present invention is further described with reference to specific embodiments, and it should be understood that the specific embodiments described herein are only used for explaining the present invention and are not used for limiting the technical solutions provided by the present invention.