Shanghai Daoqin Plastics Co., Ltd.

常规 foam plastics 泡孔直径 generally large 于50um, density (mono 位体积 inner 泡孔 数 amount) small 于1000000 /cm3. this dimensions large 泡孔受 force 时常常 formed is cracks 发源, reduce material mechanical properties. is meet/satisfy industrial upper requirements reduce certain plastics product cost reduce its mechanical properties requirements, 20世纪80 year 代初期, USA 麻省理工 large 学(MIT) 学者J.E.Martini, J.Colton以 and N.P.Suh and other 以CO2, N2 and other inert property gas as is foaming agent made 出泡孔直径 is micron grade foam plastics, will 泡孔直径 is 1～10um, density is 109～1012 /cm3 between foam plastics is micro plastics (Microcellular Plastlcs). 　　典 type micro plastics SEM照 sheet/slice 　　 micro plastics main/primary design in 于: foam plastics in dimensions small 于泡孔 internal material cracks 时, 泡孔 存 in will reduce material mechanical properties; but also, micro 孔 存 in will make material 原 存 in cracks 尖端钝化, has retardant cracks in force function lower expand 展, from make material property can to improve/increase. therefore, and foaming plastics versus ratio, micro plastics remove density can reduce 5％～95％ outer, also tool has below/following advantages: impact strong/high degree high (can foaming plastics 5倍), tough property high (can foaming plastics 5倍), ratio rigid degree high (can foaming plastics: 3～5倍), fatigue lifespan long (can foaming plastics 5倍), dielectric constant low, hot 传导因数 low. 泡孔直径 is 0.1～1um, density is 1012～1015 /cm3 foam plastics is “ ultra- micro plastics (surper MicrocellularPlastics); 当泡孔直径仅 is 0.01～0.1um．泡孔 density high 达1015～1018时 foam plastics is ”极 micro plastics (Ultra-microcellular plastics). due to this types micro plastics 泡扎直径 small can light long, can made formed transparent material. 　　 due to this 独一无二 features, micro plastics application areas non 常广泛, requirements reduce cost packaging, requirements ratio strong/high degree high and has property can machine and automotive parts; requirements quality light, can absorption can amount sports equipment, material use temperature fiber, separation process in use separation grade device; requirements scratch low surface formed and material 医学材 material, agent and catalytic agent 载体, insulation fiber and separation and other. 　　1 micro plastics molding process in key/critical steps 　　无论 using/adopting front introduction types methods production micro plastics, its molding 都包括如 lower several steps: 1) gas polymer versus system formed; 2) bubbles formed 核; 3) bubbles long large and control. this 3 steps is micro plastics processing 基础. 　　1.1 gas polymer versus system formed 　　 micro plastics extrusion production key/critical steps is industrial production speed rate formed gas 体/ polymer versus system. therefore, gas 体/ polymer versus system formed must in separation 钟甚至几十秒 inner formed. this need 采取一 特殊 measures accelerated gas polymer versus system formed. usually is in polymer molding process in melt 注入定 amount can solvent gas 体柱. formed gas 体/ polymer versus system; screw 剪切以 and gas expand dispersion function, large bubbles separation is very more small bubbles, 直至形 formed gas 体/ polymer versus system. is to this 一目, 必颁采取 this 样一 手段: 　　1) using/adopting tool has high mixed combined, high function screw 如销钉 screw; 　　2) increase mixed combined device; 　　3) will ultra- 临界CO2流体注入 polymer melt, using/adopting ultra- 临界流体 benefits is saturated and time shrink short, formed density increase, for dimensions control improvement; 　　4) using/adopting for expand dispersion technology. 　　 this application make production more small dimensions micro plastics formed is can can. due to gas deformation and 运动以 and gas versus separation 体积 不断变北, make for machine inner gas 体/ polymer versus system mixed combined property and expand dispersion mechanism analysis 变 十 separation difficult, generally need for its as 简化处理. 近似计算 and experience table/sheet 明: in extrusion process in gas 体/ polymer versus system formed can in 几十秒 inner formed. is 进一步理 understanding and add fast gas 体/ polymer solvent liquid formed, Park and other 人. research high temperature and high pressure lower gas in polymer in solvent understanding degree, expand dispersion and system for expand dispersion, for for expand dispersion process detailed analysis. 笔者认 is: is development more good mono versus gas 体/ polymer solvent liquid 连续形 formed type, 应开展 gas in high temperature high pressure lower expand dispersion and solvent understanding degree, mixed combined equipment in gas 体/ polymer mixed combined is research. 　　1.2 bubbles formed research 　　 bubbles formed is micro plastics molding also 一关健 steps. foam plastics formed mechanism main/primary has 4 types: separation 子架理论, hot formed 核理论, machine 械搅拌 formed 核理论 and interface formed 核理论 and other. in micro plastics research in. use relatively more is formed 核理论. formed 核理论 is Gibbs于20世纪初建立, most main/primary used for metal material versus research. formed 核理论 false 设亚稳态临界 bubbles 核 形 formed is in hot force balanced, 静态状态 lower 发生, micro plastics bubbles formed process is in gas saturated and lower 发生, 此时形 formed bubbles 核 需克服 自由 can and in hot force balanced conditions lower forecast value 并不一致, polymer large separation versus function will system can 变化, but also, due to gas saturated and system can 变化势必造 formed system can 变化. therefore, this factors need 考虑. J.sColton and N.P.Suh and other this factors, in formed 核理论 基础 upper micro plastics bubbles formed 核 经典 formed 核理论, will micro plastics formed type type separation is versus formed 核, nucleating agent non versus formed and non versus formed 核3 types type type. separation 别进行 research. various formed type type lower 需克服 自由 can and formed speed rate 计算公式. for versus formed 核而言, formed active can is same, formed in 整 基体 in uniform 发生; for non versus formed 核而言, formed 核发生 in types or more more material interface or certain material different micro structure interface 处, semi crystallization polymer non versus and crystallization versus, due to interface interface can relatively high, therefore formed 核 需 active can low. non versus formed 核 需 active can small, non formed easy 进行, therefore, in non versus system in, 自先发生 non versus formed 核. upper due to formed time non short, in non versus formed meanwhile, due to melt elastic retardant force function, gas separation expand dispersion can force has 限, formed local saturated and 继而发生均 versus formed 核, therefore in non versus system in is types formed process rear 发生, 即发生 mixed combined methods formed 核. value attention/notes is types formed process 发生并不意味 formed speed rate improve/increase, is 先行发生 non versus formed 核一方面消 consumption separation gas 体, make system saturated and degree decline make rear 继 均 versus formed 核 动 force small. effect/influence rear 面 均 versus formed speed rate; 另一方面, due to interface force function, small bubbles inner pressure ratio large bubbles large. 先行形 formed bubbles has rear bubbles trend, is density decline, large small non-uniform. 　　经典 formed 核理论 although to polymer large separation versus function system can 变化以 and gas saturated and 引起 自由 can 变化, has to polymer property for bubbles formed effect/influence, method forecast bubbles large small, therefore for micro plastics formed process in many phenomenon method understanding 释, in very large property. 傅志红, formed and other micro plastics bubbles formed polymer 刷子模 type, type in formed 核理论 基础 upper, can processing process parameters (temperature degree, pressure and other) and polymer material parameters (polymer molecular weight, long degree, polymerization degree and other) for bubbles effect/influence. 　　 in formed plant/unit 方面, main/primary has gears and fast speed drop pressure 口模两 types; gears used as formed plant/unit main/primary is utilizing gears increase pressure function improve/increase melt pressure. in this type of micro plastics extrusion in, is in machine rear 端安装一 gears 泵, rear upper extrusion machine 头. gas 体/ polymer system gears 泵 入口 rear, gears and inner formed 密闭 空间,随 gears 转动,密闭 空间越 越 small, make polymer melt pressure increase large, from improve/increase melt pressure. system from melt 泵流出 rear speed pressure. from formed a large amount of bubbles 核. gears advantages is suitable for various product, but also can processing high degree polymer (due to pressure drop non scratch property). utilizing gears improve/increase system pressure has 两 方面 defect: 　　1) cost improve/increase; 　　2)会 add extrusion unstable property. 　　 fast speed drop pressure 口模. is currently in 实验室 in use most more types formed plant/unit. its principle is through long runner achieve fast speed drop pressure. fast speed drop pressure pressure drop and 口模直径, long degree, amount and material property has 关. fast speed drop pressure 口 injection molding parts mold has structure simple and easy control and other advantages ．但 usually amount to made. 　　1.3 bubbles long large and type 　　 in micro plastics molding process in, formed stage/phase main/primary micro plastics in density and distribution, long large and type main/primary 决定泡孔 large small, 形状, and distribution 状况. is in long large process in, CO2容 easy from table/sheet 皮逸出. but also, 以CO2, N2 and other inert property gas as is gas foaming agent 时, its molecular weight small, its expand dispersion rate high 于常规 long foaming agent 如戊烷 or and other. foam plastics extrusion machine rear, already expand dispersion bubbles in gas toward expand dispersion to ring in, is hot force more toward will versus full separation 离. gas from thin 壁逸出 will decrease/reduce used for bubbles long large gas 体, its rear is: if bubbles has solid, 则会出现塌陷, from 而引起 foam plastics shrinkage. therefore, is to low density micro foam plastics, must retardant bubbles from table/sheet expand dispersion. retardant bubbles from table/sheet expand dispersion methods is make extrusion material table/sheet cooling solid. is temperature degree reduce, expand dispersion rate reduce. therefore, gas 体 逸出 rate can through solid foam plastics table/sheet reduce. extrusion material table/sheet can through reduce machine temperature degree add cooling. machine temperature degree can through ring machine low temperature cooling 油 以精确 control. another, machine polymer melt temperature degree effect/influence gas dispersion to ring 境 效果, is gas in bubbles expand dispersion rate can through reduce melt temperature degree add retardant 止, but also, temperature degree reduce increase melt rigid degree, retardant due to gas decrease/reduce shrinkage. 　　 research bubbles long large process, must research bubbles long large force and retardant force. due to polymer melt property complex property, gas and melt also in has quality, amount and hot amount complex process, need 精确描述 bubbles long large process is separation difficult. Rayleigh research in liquid in, bubbles and 塌陷. Street research in and other temperature conditions lower, mono bubbles in 静止幂律流体 in expand dispersion control bubbles long large process. Epstei and Plessct also will research scope/range expand to polymer melt, 并提出 experience 公式: liquid retardant force and gas liquid between process effect/influence, Barlow and Longois research and other temperature, 静止牛顿流体 in mono bubbles long large process, will bubbles long large process separation is stage/phase, grade stage/phase growth speed rate and time formed positive ratio, rear stage/phase (also 称渐进线 stage/phase) growth speed rate and time 平方根 formed ratio/proportion, stage/phase growth speed rate 取决于 gas expand dispersion speed rate. Zana and Leal research 牛顿流体 and elastic melt in expand dispersion bubbles phenomenon. Street结 combined amount, quality and can amount 传递, using/adopting thin housing/shell 近似计算 methods (即 false 设传递 process in outer has thick degree thin inner)进行求 understanding. 　　描述 bubbles long large type main/primary has 海岛模 type and fine type types. 海岛模 type research mono bubbles in melt in long large process, has bubbles and bubbles between versus effect/influence and bubbles combined 并; fine type bubbles in has film inner long large process, comparison true 实 反映 melt in bubbles meanwhile long large versus 互关系, to 人们 普遍接受. 　　 effect/influence bubbles long large factors very more, system material property parameters (gas solvent understanding degree, expand dispersion 因数, melt elastic property, gas liquid interface surface force and other) and processing process parameters (temperature degree, pressure, speed rate and other). 　　 is to combined design requirements most micro plastics, bubbles type control important. formed rear has unstable bubbles long large and separation long large trend, is formed bubbles long large, due to through bubbles combined can decrease/reduce surface from reduce system can, therefore versus bubbles has combined trend. meanwhile, molding process in generate 剪切场倾 toward long formed bubbles, from 而进一步 accelerated bubbles combined 并. bubbles can 无约束 long large 时, 就会变 unstable, bubbles 壁 破裂. decrease small bubbles density. therefore, is to micro structure, must made bubbles combined 并. 　　2 LDPE micro plastics extrusion molding research 　　以 low density polyethylene (PE) (LDPE) as is Raw Materials, ultra- 临界CO2, as is foaming agent, in SJZ-45A type di screw extrusion machine micro plastics extrusion molding research. formed plant/unit using/adopting made fast speed drop pressure 口模. 　　 for sample 进行 扫描 electrical 镜(SEM) analysis, according to SEM照 sheet/slice analysis, 出泡孔直径 and density extrusion pressure, pressure drop speed rate and extrusion temperature degree 变化规律如 lower. 　　2.1 pressure for bubbles effect/influence 　　图2 is in machine temperature degree is 170℃时．口模入口 pressure separation is 10MPa, 11MPa, 15MPa, 22MPa时LDPE foam plastics SEM照 sheet/slice, 图3 is LDPE foam plastics in 泡孔直径随口模 pressure 变化曲线, 图4 is density 随口模 pressure 变化曲线. 　　 in 图3 in also in polymer melt temperature degree is 170 ℃时临界 bubbles semi pressure 变化曲线. from this can 知, 泡孔 直径随 extrusion pressure increase decrease small, density pressure increase increase. 　　2.2 pressure drop speed rate for bubbles effect/influence 　　 bubbles formed is due to system hot force unstable property 引起, hot force unstable property degree 取决于 pressure drop speed rate, therefore pressure drop speed rate large, formed speed rate and formed density versus increase large. 图5: is types different pressure drop speed rate lower foam plastics SEM照 sheet/slice. 　　图6 is 泡孔直径随 pressure drop 变化 曲线, 间接反映 pressure drop for bubbles effect/influence. 图7 is density pressure drop 变化曲线, 间接反映 pressure drop for formed density effect/influence. 　　2.3 temperature degree for bubbles effect/influence 　　 extrusion mold temperature degree for micro plastics molding effect/influence main/primary performance in below/following several 方面: 　　1) temperature degree rise high can reduce interface force, according to bubbles formed polymer 刷子模 type, can make formed bubbles semi decrease small. 　　2) gas in polymer melt in solvent understanding degree generally temperature degree rise high reduce, therefore, temperature degree improve/increase 时, gas solvent understanding degree versus reduce, 不利于 micro plastics formed 核. 　　3)随 temperature degree rise high polymer melt strong/high degree (according to 定义, polymer melt strong/high degree can is is bubbles 发生膨胀时, in bubbles 壁周围 流域 in, bubbles for 延伸流 retardant degree)会 reduce ． from reduce bubbles stability property, make bubbles easy combined 并, and other phenomenon, 不利于 micro plastics processing. 　　综 upper 述, in micro plastics processing process in, improve/increase temperature degree has micro plastics molding. 　　图8 is in machine 头口模入口 pressure is 11MPa lower, in different temperature degree lower foam plastics SEM照 sheet/slice (use is Ⅲ号). 圈9 is 泡孔直径随 temperature degree 变化曲线, 圈10 is density temperature degree 变化曲线. in 图8 in, also pressure is 22MPa时临界 bubbles semi temperature degree 变化曲线. from 图9 and 图10 can 看出, temperature degree low certain value 时, 泡孔直径随 temperature degree rise high decrease small, density temperature degree improve/increase increase large. temperature degree ultra- 一定 value 时, 泡孔直径反而随 temperature degree improve/increase increase, density temperature degree increase decrease small. this is due to dimensions and density is formed and long large comprehensive 反映. in high temperature 时, bubbles long large speed degree non fast, bubbles combined phenomenon 占 主导 位, make products dimensions large 于不发生 bubbles combined and 塌陷时 bubbles dimensions, density low formed density (versus for temperature degree light low 时). 　　3结束语　　 micro plastics as is types new type material, tool has non excellent property can and vast application areas. already 引起发达国家 high degree heavy 视, many company USA Trexcl, Microcellular Plastics Techonology, Axiomatics company; Japan SeKISUI Plasticsof Tokyo company; add large Engel company and other already force micro foaming technology application development and 商业化推广. inner from 1995 year research micro plastics, in upper 取碍 一定进展, already in 实验室 made multiple Model/Grade micro plastics. rear, high versus 继进行 micro plastics research. micro plastics industry also has 一段距离, also need as a large amount of property research as.