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  • 塑料人必备的改性知识汇总
  • 本站编辑:杭州宇篷科技有限公司发布日期:2019-08-18 11:03 浏览次数:
改性是改的什么性
在通用塑料和工程塑料的基础上,通过物理、化学、机械等方式,经过填充、共混、增强等加工方法,改善塑料的性能或增加功能,对塑料的阻燃性、强度、抗冲击性、韧性等机械性能得到改善和提高,使得塑料能适用在特殊的电、磁、光、热等环境条件下。
改性技术的应用范围
从原料树脂的生产到多种规格及品种的改性塑料母料的生产,广泛应用于几乎所有的塑料制品的原材料与成型加工过程中。
如塑料的外观、透明性、密度、精度、加工性、机械性能、化学性能、电磁性能、耐腐蚀性能、耐老化性、耐磨性、硬度、热性能、阻燃性、阻隔性等方面。为了降低塑料制品的成本、改善性能、提高功能,都离不开塑料改性技术。
常用的改性方法
1、填充改性
通过给普通塑料加入无机矿物(有机)粉末,改善塑料材料的刚性、硬度、耐热性等性能。填充剂种类繁多,其特性也及其复杂。
塑料填充剂的作用:提高塑料加工性能、改进物化性质、增加容积、降低成本。
对塑料添加剂的要求:
(1)化学性质不活泼,呈惰性,不与树脂及其他助剂发生不良反应;
(2)不影响塑料的耐水性、耐化学药品性、耐候性、耐热性等;
(3)不降低塑料的物理性能;
(4)可以大量填充;
(5)相对密度小,对制品的密度影响不大;
(6)价格相对低廉。
2、增强改性
增强措施:通过在加入玻璃纤维、碳纤维等纤维状物质。
增强效果:可以明显改善材料的刚性、强度、硬度、耐热性,
改性的不良影响:但很多材料会导致表面不良和断裂伸长率降低。
增强原理:
(1)增强材料具有较高的强度和模量;
(2)树脂具有许多固有的优良物理、化学(耐腐蚀、绝缘、耐辐照、耐瞬时高温烧蚀等)和加工性能;
(3)树脂与增强材料复合后,增强材料可以起到增进树脂的力学或其他性能,而树脂对增强材料可以起到粘合和传递载荷的作用,使增强塑料具有优良性能。
3、增韧改性
有较多的材料韧性不够、太脆,可以通过加入韧性较好的材料或者超细无机材料,增加材料韧性和低温使用性能。
增韧剂:为了降低塑料硬化后的脆性,提高其冲击强度和延伸率而加入树脂中的一种添加剂。
常用增韧剂——多为马来酸酐接枝相容剂:
乙烯-醋酸乙烯酯共聚物(EVA)
聚烯烃弹性体(POE)
氯化聚乙烯(CPE)
丙烯腈-丁二烯-苯乙烯共聚物(ABS)
苯乙烯-丁二烯热塑性弹性(SBS)
三元乙丙橡胶(EPDM)
4、阻燃改性
在电子电器、汽车等很多行业要求材料有阻燃性,但很多塑料原料本身的阻燃性较低。提高阻燃性可以通过加入阻燃剂实现。
阻燃剂:又称难燃剂,耐火剂或防火剂,赋予易燃聚合物难燃性的功能性助剂;它们大多是元素周期表中第ⅤA(磷)、ⅦA(溴、氯)和ⅢA(锑、铝)族元素的化合物。
具有抑烟作用的钼化合物、锡化合物和铁化合物等亦属阻燃剂的范畴,主要适用于有阻燃需求的塑料,延迟或防止塑料尤其是高分子类塑料的燃烧。使其点燃时间增长,点燃自熄,难以点燃。
塑料阻燃等级:
由HB,V-2,V-1,V-0,5VB 向5VA逐级递增。
5、耐候改性
一般指塑料在低温下的耐寒能力,由于塑料固有的低温脆性,使塑料在低温下变脆,因而对于很多在低温环境下使用的塑料制品,一般要求其具有耐寒性。
耐候性:是指塑料制品因受到阳光照射,温度变化,风吹雨淋等外界条件的影响,而出现的褪色、变色、龟裂、粉化和强度下降等一系列老化的现象。紫外线照射是促使塑料老化的关键因素。
6、改性合金
塑料合金是利用物理共混或化学接枝、共聚的方法,将两种或多种材料制备成高性能、功能化、专用化一种新材料,达到改善一种材料的性能或兼具两种材料特性的目的。它能改善或提高现有塑料的性能并降低成本。
通用塑料合金:如PVC、PE、PP、PS合金使用广泛,生产技术已被普遍掌握。
工程塑料合金:泛指工程塑料(树脂)的共混物,主要包括以PC、PBT、PA、POM(聚甲醛)、PPO、PTFE(聚四氟乙烯)等工程塑料为主体的共混体系,以及ABS树脂改性材料。
PC/ABS合金的产量每年都以10%左右的速度增长,其增速在塑料领域中排在前列。目前,PC/ABS合金化研究已经成为高分子合金研究热点。
改性塑料的主要类别
改性塑料的主要细分类别、消费群体及市场应用情况。
1阻燃树脂类
阻燃塑料产品可大大减少发生短路、过载、水浸等情况时产生火灾的风险。
2增强增韧树脂类
主要分为耐候增韧PP专用料、玻纤增强热塑性塑料等产品。
(1)耐候增韧PP专用料:耐候增韧PP专用料是一种具有工程塑料特性的聚丙烯新材料,具有低温韧性好、成型收缩率小、刚性高、耐候性强等优点,主要用于需耐气候、紫外线的户外环境。其主要消费群体有家电企业,汽车零部件企业等。
(2) 玻纤增强热塑性塑料类:产品主要有玻纤增强AS/ABS、玻纤增强PP、玻纤增强尼龙、 玻纤增强PBT/PET、玻纤增强 PC、玻纤增强PPE/PPS等。其主要消费群体有电脑配件企业、机械零部件企业、电动工具企业、灯具企业等。
3塑料合金类
主要分为PC合金、PVC合金以及聚酯合金等。
PC合金产品特点:冲击强度高、抗蠕变性、耐热、吸水率低,无毒、介电性优良等特点。
PC合金应用:汽车仪表面板、计算机和办公室自动化设备、电动工具外壳、蜂窝电话等。
PVC/ABS合金:以PVC和ABS为基体,添加增韧剂、润滑剂、稳定剂、阻燃剂等多种改性剂生产而成。
性能优势:优异的力学性能、耐候性能、加工流变性能,制品表面光泽好,注塑、挤出效果好,是一种性价比极为优异的合金材料。
应用范围:可以替代阻燃耐候ABS、PC等,应用于家电外壳、电器开关、电表外壳、灯饰材料、通讯网络、建材等方面。
聚酯合金:具有优异的机械性能(耐疲劳)、尺寸稳定性、耐化学试剂、耐环境应力开裂的能力,应用范围:汽车、家电、电动工具等领域。
4功能色母类
主要是指高抗冲聚苯乙烯增韧阻燃色母料。 
功能色母的特点——既能降低生产成本又能提高产品品质。
(1)满足UL94、IEC-65和GB8898等标准对电器、电子产品的阻燃要求;
(2)改善HIPS树脂的韧性、加工流动性和脱模性;
(3)赋予HIPS树脂颜色。
What is modification
 
On the basis of the general plastics and engineering plastics, by physical, chemical, machinery, after filling, blending, and enhance processing method, improves the performance of the plastic or increase the function of the plastic flame retardancy, strength, impact resistance, toughness and other mechanical performance is improved and improve, so that you can apply plastic in special environment, such as electric, magnetic, optical, thermal conditions.
 
Application scope of modification technology
 
From the production of raw material resin to the production of various specifications and varieties of modified plastic masterbatch, it is widely used in the raw material and molding process of almost all plastic products.
 
Such as plastic appearance, transparency, density, precision, processing, mechanical properties, chemical properties, electromagnetic properties, corrosion resistance, aging resistance, wear resistance, hardness, thermal properties, flame retardant, barrier and other aspects. In order to reduce the cost of plastic products, improve the performance, improve the function, are inseparable from the plastic modification technology.
 
Common modification methods
 
1. Filling modification
 
By adding inorganic mineral powder to ordinary plastics, the rigidity, hardness and heat resistance of plastics are improved. There are many kinds of fillers and their properties are very complex.
 
The function of plastic filler: improve plastic processing performance, improve physical and chemical properties, increase volume, reduce cost.
 
Requirements for plastics additives:
 
(1) the chemical properties are inactive and inert, and there are no adverse reactions with resins and other auxiliaries;
 
(2) does not affect the water resistance, chemical resistance, weather resistance, heat resistance, etc.;
 
(3) does not reduce the physical properties of plastics;
 
(4) can be filled in large quantities;
 
(5) low relative density has little influence on the density of products;
 
(6) the price is relatively low.
 
2. Enhanced modification
 
Reinforcement: by adding fiberglass, carbon fiber and other fibrous substances.
 
Strengthening effect: it can significantly improve the rigidity, strength, hardness and heat resistance of the material.
 
Adverse effects of modification: however, many materials can lead to poor surface and reduced elongation at break.
 
Enhancement principle:
 
(1) reinforced materials have high strength and modulus;
 
(2) resin has many inherent excellent physical and chemical (corrosion resistance, insulation, radiation resistance, instantaneous high temperature ablation, etc.) and processing properties;
 
(3) when the resin is combined with the reinforcing material, the reinforcing material can improve the mechanical or other properties of the resin, while the resin can play the role of bonding and transferring the load to the reinforcing material, so that the reinforced plastic has excellent properties.
 
3. Toughening and modification
 
There are many materials with weak toughness and too brittle. Materials with good toughness or ultra-fine inorganic materials can be added to increase the toughness and low-temperature performance of materials.
 
Toughening agent: an additive added to a resin to reduce the brittleness of plastics after hardening and to increase their impact strength and elongation.
 
Common toughening agent -- mostly maleic anhydride graft compatibilizer:
 
Vinyl acetate copolymer (EVA)
 
Polyolefin elastomer (POE)
 
Chlorinated polyethylene (CPE)
 
Acrylonitrile-butadiene-styrene copolymer (ABS)
 
Styrene-butadiene thermoplastic elasticity (SBS)
 
Ethylene propylene diene diene rubber (EPDM)
 
4. Flame retardant modification
 
In many industries, such as electronic appliances and automobiles, materials are required to be flame retardant, but many plastic materials themselves have low flame retardancy. Increased flame retardancy can be achieved by adding flame retardants.
 
Flame retardants: also known as flame retardants, fire retardants or fire agents, to give flammable polymer flame retardant functional AIDS; Most of them are in the periodic table first Ⅴ (p), A Ⅶ A (bromine, chlorine) and Ⅲ A elements of compounds, antimony, aluminium).
 
Molybdenum compounds, tin compounds and iron compounds with smoke inhibition are also flame retardants, which are mainly applied to plastics with flame retardant requirements, to delay or prevent the burning of plastics, especially polymers. Make its ignition time increase, ignition self-extinguishing, difficult to ignite.
 
Flame retardant grade of plastics:
 
From HB, v-2, v-1, v-0, 5VB to 5VA gradually increased.
 
5. Weather-resistant modification
 
Generally refers to the cold tolerance of plastics at low temperature. Due to the inherent low temperature brittleness of plastics, plastics become brittle at low temperature. Therefore, for many plastic products used in low temperature environment, it is generally required to have cold tolerance.
 
Weather resistance: refers to plastic products due to exposure to sunlight, temperature changes, wind and rain and other external conditions, and the appearance of fading, discoloration, cracking, powder and strength decline and other aging phenomenon. Ultraviolet radiation is the key factor of aging plastic.
 
6. Modified alloy
 
Plastic alloy is a new kind of material with high performance, function and special purpose, which is prepared by physical blending or chemical grafting and copolymerization. It improves or improves the properties of existing plastics and reduces costs.
 
General plastic alloy: such as PVC, PE, PP, PS alloy is widely used, production technology has been widely mastered.
 
Engineering plastic alloy: generally refers to the blends of engineering plastics (resins), which mainly include the blends of PC, PBT, PA, POM (poformaldehyde), PPO, PTFE (teflon) and other engineering plastics, as well as the modified materials of ABS resin.
 
The output of PC/ABS alloy is increasing by about 10% every year, which ranks the forefront in the plastic field. At present, PC/ABS alloying has become a hot spot in polymer alloy research.
 
The main categories of modified plastics
 
The main subdivision categories, consumer groups and market application of modified plastics.
 
1 flame retardant resin class
 
Flame retardant plastic products can greatly reduce the risk of fire when short-circuit, overload, flooding and other conditions.
 
2 reinforced and toughened resin
 
Mainly divided into weather-resistant toughening PP special materials, glass fiber reinforced thermoplastics and other products.
 
(1) special material for weather-resistant toughening PP: special material for weather-resistant toughening PP is a new polypropylene material with the characteristics of engineering plastics. It has the advantages of good low-temperature toughness, small molding shrinkage, high rigidity, strong weather resistance, etc. It is mainly used in outdoor environment that needs to withstand climate and ultraviolet rays. Its main consumer groups are home appliance enterprises, auto parts enterprises and so on.
 
(2) glass fiber reinforced thermoplastics: the main products are glass fiber reinforced AS/ABS, glass fiber reinforced PP, glass fiber reinforced nylon, glass fiber reinforced PBT/PET, glass fiber reinforced PC, glass fiber reinforced PPE/PPS, etc. Its main consumer groups are computer parts enterprises, machinery parts enterprises, power tools enterprises, lighting enterprises and so on.
 
Plastic alloys
 
It is mainly divided into PC alloy, PVC alloy and polyester alloy.
 
PC alloy features: high impact strength, creep resistance, heat resistance, low water absorption, non-toxic, excellent dielectric properties.
 
PC alloy application: automobile instrument panel, computer and office automation equipment, power tool housing, cellular phone, etc.
 
PVC/ABS alloy: it is made of PVC and ABS as the matrix, adding toughening agent, lubricant, stabilizer, flame retardant and other modifiers.
 
Performance advantages: excellent mechanical properties, weather resistance, processing rheological properties, good surface gloss, injection, extrusion effect is good, is an excellent cost-effective alloy materials.
 
Application: it can replace the flame retardant and weather resistant ABS, PC, etc. It can be applied to the housing of home appliances, electrical switches, electric meter housing, lighting materials, communication network, building materials, etc.
 
Polyester alloy: excellent mechanical properties (fatigue resistance), dimensional stability, chemical reagents, environmental stress cracking ability, application: automotive, household appliances, power tools and other fields.
 
4 functional color master class
 
Mainly refers to high impact polystyrene toughened flame retardant color masterbatch.
 
Features of functional color masterbatch - can reduce production cost and improve product quality.
 
(1) meet the flame retardant requirements of electrical and electronic products required by UL94, iec-65 and GB8898;
 
(2) improve HIPS resin toughness, processing liquidity and demodulate;
 
(3) give HIPS resin color.