分散剂的分子结构和在配方中应用的重要性.

wyj7506 · 发表于 2008-10-7 11:44:57

本帖最后由 wyj7506 于 2009-12-3 15:07 编辑

分散剂的分子结构和在配方中应用的重要性.

王盛龙
谈谈分散剂
摘要:分散剂的分子结构和在配方中应用的重要性.
在涂料配方设计中有些存在很多的误区.认为分散剂无关紧要.其是不然,分散剂在涂料配方中起着非常重要的作用,它迁涉到,光泽,流平,丰满度,以及施工的性能和生产效益以及存储等等方面.现将Ciba的EFKA分散剂的组成及分子结构和应用提给大家也许有一些帮助.
溶剂型分散剂
但润湿分散剂不应作为表面活性剂中用来提高液体树脂流平性或者防止缩孔形成的基材润湿剂的一员来考虑。涂料或者油墨干膜层的质量强烈地依赖于固体粒子在树脂体系中良好而均一地分散。诸如着色力差，遮盖力不足，光泽低，耐候性降低等缺陷是涂料技术人员所知道的典型例子。而且，差的分散体系导致干膜的机械性能变差。为了获得良好的分散体系，固液界面必须在研磨阶段得到改进。
在研磨过程中，大块颜料和颜料凝聚体被粉碎成接近初级粒子，同时新形成的表面被液体载体湿润。
润湿剂的使用能提高液相润湿颜料表面的速度。　研磨阶段是涂料和油墨生产过程中最耗时，耗能的重要阶段。
另外值得重要考虑的是新的粒子分散体的连续稳定性。
絮凝能导致分散体发生颜色偏移，沉降和粘度变化。絮凝的起因是建立在粒子布朗运动的基础上。
微小的粒子（粒径0.01-1微米）在悬浮液中自由移动，相互碰撞形成絮凝，降低总能量。粒子越小，絮凝作用越强。
粒子越小，浓度越高，相遇的可能性越大，絮凝倾向越强。
稳定机理
按科学的方法，主要分为两种稳定机理：静电排斥和空间位阻。当粒子表面带有相同的电荷而发生排斥时便形成静电稳定，由于这种机理依赖于带电离子排斥，因此主要对于象水性涂料这种高极性体系有用。
静电排斥
粒子周围的电荷形成一个双电层，每层带有等量的电荷，当两个粒子相互接近时它们所带的双电层发生交迭并产生排斥，同时伦敦－范德瓦力使粒子相互吸引。如果吸引力大于排斥力，分散就不稳定。而如果排斥力占优，体系就不会絮凝。空间位阻稳定是由所吸附的高分子带来的作用，它对水性体系和溶剂型体系都适用。
这种稳定依赖于吸附的高分子层的结构和厚度，一般说来，有效的空间位阻稳定必须具有几个条件：粒子表面必须被分散剂完全包覆，　高分子层的直径足够大，高分子必须被有力的吸附在表面避免在分散体碰撞或稀释时脱吸。空间位阻链应该是线性的并且可以伸展到介质中形成保护层。
Dispersing agents Solvent-based
They should not be considered asmember of the substrate-wetting group of surfactants which are used toimprove the leveling of a liquid resin formulation or to prevent theformation of craters。
The quality of a dry paint or ink film isstrongly dependant on howfinely and uniformly distributed are the solidparticles in the resinmatrix。Defects like poor colour strength,insufficient hiding power low glossand decreased weather resistance aretypical examples known to thetechnician。Furthermore, a poorly dispersedsystem results inferior mechanical properties of the dry film。To obtaina finely dispersed system, the solid-liquid interface has to bemodified during the grinding step。
During grinding, the pigment agglomerates and aggregates are crushedtoprimary particles and the newly formed surfaces are wetted bytheliquid carrier。
The use of a wetting agent can increasethe speed at which the liquid phase wets the pigment surface
Thisisimportant as the grinding step is the most time- andenergy-consumingphase during the paint and ink production process。Another importantconsideration is the consecutive stabilization ofthe fresh dispersionof the particles 。
Flocculation can cause colour shift, sedimentation and changes in viscosity of the dispersion。
The origin of flocculation is found in the Brownian motion of particles
Smallparticles(typically 0.01-1 micron) move randomly in the suspension,collide witheach other and form flocculates, reducing their totalenergy. Thesmaller the particles, the stronger the flocculation。
If,in additionto being smaller, their concentration is also high, theprobability ofencounter is increased and the tendency to flocculationis increased。

Stabilization mechanism
Scientifically, two main stabilization mechanisms can be distinguished: electrostatic and steric stabilization.
Electrostaticstabilization takes place when particles bear the same electricalsurface charge and as a result, repulsion take place。As this mechanismrelies on the separation of ionic charges,it is mainly relevant insystems of high polarity like aqueous paints。
Electrostatic repulsion
The charge around the particle is organized into a double layer in which each layer possesses equal Charge
Whentwo particles approach one another, their charged double layers overlapand repulsion take place，At the same time, London-van-der-Waals forcesleads to attraction of the particles
If the attractive forces arestronger than the repulse forces, the dispersionwill be unstable.However, if repulse forces predominate, the system will benon-flocculating
Steric stabilization is brought about by adsorbed polymers and applies to both water- and solvent-based sytems
This stabilization is dependant on the structure and dimensions of the adsorbed polymer layer。
In general, effective steric stabilization has to fulfill severalconditions: the particle surface has to be totally covered withdispersant，the layer has to be of sufficient diameter，the polymer hasto be strongly adsorbed on the surface to avoid de-adsorption uponcollision or dilution of the dispersion，the steric chains should belinear and extend into the medium to build up a protective layer。
Steric stabilization
空间位阻稳定
聚合物通过在粒子表面具有强烈化学吸附能力的“锚定基团”或者链段吸附在粒子上，聚合物的其余链段能与树脂相混溶并能伸展到树脂介质中，这些具有稳定作用的聚合物伸展开来的部分成为两个相互接近粒子最先接触的部分，邻近的颜料粒子所带的聚合物层之间会有一定程度的互穿，随着距离的减小溶解链段的浓度升高，体系的自由能也随之升高。由于渗透压的作用，溶剂分子开始向聚合物层相互渗透的区域迁移并使两个粒子重新分开，直到达到一个较低的能量水平。以这种方式获得渗透与排斥之间的平衡。吸附层的厚度决定着粒子之间的距离是否足够大以克服分子间的范德瓦力。
在稳定的分散体中两个颜料粒子间的最小距离
实际中通常公认的是要达到有效距离要求分子量至少在5000g/mol(对于大多数粒子100 Å的吸附厚度被认为是最理想的）
日常实践中，涂料和油墨工业既使用低分子量润湿分散剂（ <2000 g/mol）也使用高分子量润湿分散剂（ 5000-25000g/mol)

The polymer can adsorb onto a particle through the so-called “anchoring groups” or segments that have strong affinity for the chemistry of the surface
The remainder of the polymer can be seen as dissolved and can extend into the resin medium
These extended parts of the stabilizing polymer become the first contacts between two approaching particles
A certain degree of inter-penetration between the polymer layers from the adjacent pigments particles is possible
As the concentration of solvated chains increases with decreasing distance, the free energy of the system increases
Asa result of osmotic pressure, the solvent molecules start to migrateinto the zone of the penetrating polymer layers and re-separate the twoparticles until a lower energy level is reached，In this way equilibriumis attained between penetration and repulsion，The diameter of theabsorbed layer determines whether the distance
Between the particles is large enough to overcome the van-der-Waals attraction forces between the molecules。
Minimum distance between two pigment particles in a stable dispersion
Inpractice it is generally accepted that a molecular weight of at least5000 g/mol is required to achieve sufficient distance (100Å isconsidered to be optimal for most particles
In day-to-day practice,the paint and ink industries employ low molecular weight (<2000g/mol) as well as high molecular weight (5000-25000 g/mol) wetting anddispersing agents。

High Molecular Weight Polymeric Dispersants 4000 – series  4000系列    高分子量聚合物分散剂
5000-serie Conventional Wetting and Dispersing Agents  5000系列  传统式润湿分散剂
功能和特性
designed for inorganic fillers/pigments 为无机填料/颜料而设计
reduction of surface tension at the solid/liquid interface在固/液界面降低表面张力
anchoring groups adsorb to charged surfaces锚定基团吸附到带电表面
good compatibility with the medium与介质有良好的相容性
separation of inorganic particles by wetting通过润湿使无机粒子相互分开
stabilization of inorganic particles by controlled flocculation通过可控絮凝稳定无机粒子
Categorisation according to chemical structure依据化学结构分类
Classes and typical examples of conventional W&D Agents.传统润湿分散剂的分类与典型例子
CATIONIC 阳离子型如：油酰胺 ANIONIC阴离子型  如：钠盐
oleylamine oleate
电中性型油酰胺盐
NON-IONIC 非离子型 aliphatic polyether
The effectiveness of wetting and dispersing agents is determined by two moieties:润湿分散剂的效力由两部分决定：
脂肪族聚醚
the interaction of the polar head of the molecule with the surface of the pigment-分子的极性端与颜料表面的吸附作用
the behaviour of the non-polar hydrocarbon tail in the medium非极性烷基尾链在介质中表现行为
In certain polar media, free molecules are drawn to those already attached to the pigment surface through apolar-apolar interaction of the tails. This interaction takes a reverse position in respect to the first layer of the molecules.
在某一极性介质中，游离的分散剂分子通过非极性尾链间的吸附作用被拉向那些已经吸附在颜料表面的分子。这种相互所用使附于第一分散剂层上的分子处于翻转位置, 即非极性链段部分朝内,极性端基部分朝外。
The polar heads will form hydrogen bonding interactions between different pigment units resulting in a network that enhanced the separation of the particles (controlled flocculation)
那些朝外的极性端会在不同的颜料聚集体间形成氢键作用进而形成网状结构，这种网状结构增强了粒子的分隔（控制絮凝）
This interaction is of great importance in this class of dispersants since the relative low molecule weight (800-1000) will not give sufficient sterical hindrance由于相对比较低的分子量（800-1000)不能提供有效的空间屏蔽，致使这种相互作用对于这类分散剂非常重要。
The difference in the interaction density among the various types of dispersants determines the grade of the controlled flocculation. This interaction is strongly influenced by the amount of polar heads present in the liquid phase as well as the polarity of the medium
不同类型的分散剂吸附密度的差异决定了控制絮凝的等级。这种吸附作用受液相中极性端数量和介质极性的强烈影响。
Wetting and Dispersing agents 润湿分散剂controlled flocculation 控制絮凝如50系列的分散剂
4000-series High Molecular Weight Polymeric Dispersants4000－系列高分子量聚合物型分散剂
In order to achieve a strong interaction between the surface of organic pigments and the dispersing agents, EFKA developed different types of dispersants which have main common features: they are build of high molecular weight polymers (5000-30000) which in general have a polyurethane or polyacrylate structure为了在有机颜料表面与分散剂之间获得强吸附作用，EFKA开发了不同类型的分散剂，这些分散剂的主要通性是：都是高分子量聚合物(5000-30000)，一般分为聚氨酯型结构和丙烯酸酯型结构。
Main differences between the polymeric dispersants and the conventional wetting and dispersing agents:
高分子量分散剂和传统式润湿分散剂的分别
anchoring mechanism chemical structure锚定机理化学结构molecular weight分子量
Classification of pigments and characterisation of the surfaces 颜料的分类和其表面性质
无机：  charged particles带电荷的颗粒
crystal lattice 晶体点阵
metal oxides as 金属氧化物如TiO2, Fe2O3, CrO3
surface + (metal ions) and - (oxygen ions)表面＋（金属离子）和－（氧化离子）
surface of a rutile TiO2(octahedral arrangement)
金红石型的TiO2表面（八面结构）distribution of the charges on the surface表面电荷的分布
Organics:  有机    consist mainly of C, H, O and N atoms主要由C,H,O原子组成
covalent bonds共价键conjugation with aromatic rings gives colour共轭型的苯环为发色团
Perylen-Pigment PR 179苝红类
Mono-azo-Type PY 154单偶氮类
Isoindolin-Pigment PY 139异吲哚啉酮类
Naphtol AS-Pigment PR 170偶氮萘酚类
Anchoring mechanisms锚定机理
Review: conventional w&d agents回顾：传统式润湿分散剂
effective by interaction of the polar head with the surface of the pigment/filler and compatibility of the chain in the medium
-通过极性端基对颜料/填料表面吸附同时非极性链与介质相溶而发挥作用
strong affinity to inorganic surfaces (+ and - charges)
对无机颜料表面具有强吸引力（正电荷和负电荷）
not effective with organic pigments (covalent bonds of C, H, N, O atoms)-对有机颜料无效（C,H,N,O原子的共价键）
Anchoring mechanisms 锚定机理
Polymeric Dispersants: 高分子量分散剂
anchoring groups that have ability to adsorb to organic surfaces (C, H, N, O atoms) and inorganic surfaces (charged)
能够吸附在有机颜料表面(C,H,N,O原子)和无机颜料（带电荷）的锚定基团
Physical adsorption:物理吸附：hydrogen bonding 氢键 dipoleLondon/van-der-Waals forces 伦敦－范德瓦力
-dipole intinteraction by numerous anchoring groups in one polymer chain聚合物链上的大量锚定基团的吸附作用eraction  偶极引力
Anchoring mechanisms锚定机理Polymeric Dispersants:高分子量分散剂
hydrogen bonding氢键 Different electro negativities(strong bindings)不同的电极性（强键）
dipole-dipole interaction偶极引力
Anchoring mechanisms锚定机理：Polymeric Dispersants:高分子量分散剂：London-Van der Waals Forces                         伦敦－范德瓦力 (similar chemical structure)（相似的化学结构）
Polymer backbone聚合物背脊 Polymer backbone聚合物背脊
Anchoring mechanisms锚定机理
Polymeric Dispersants:聚合物分散剂：
conventional W&D Agent    polymeric Dispersants
聚合物分散剂                   传统润湿分散剂
remaining part acts as steric barrier， preventing reflocculation caused by Brownian motion
支链部分起空间屏蔽作用，防止布朗运动引起的再絮凝
Problems related to flocculation by insufficient stabilisation:由于不足的稳定作用引起絮凝而带来的问题：
pigment flooding / rub-out ，poor colour stability颜色稳定性差料浮色不能通过指擦实验
lack of gloss失光
poor hiding power and colour strength遮盖力和着色力变差
increased viscosity粘度升高
Synaeresis色漆中颜料与基料分层
Solved by efficient steric hindrance通过有效的空间位阻来解决上述问题
The special properties of HMW-Polymeric Dispersing Agents: 高分子量分散剂的特殊性能
Very efficient in preventing flocculation. 非常有效地防止絮凝
They work with both inorganic and organic pigments.对有机颜料和无机颜料都起作用。
A strong viscosity reducing effect.具有强烈的降粘效果
This is important where high pigment loadings are being used.这对于使用高颜料含量的场合很重要
Excellent compatibility.优异的相溶性。Only small quantities are required to stabilise the pigments without flocculation.
High resistance to humidity and chemicals.高耐湿性和高耐化学性。
HMW-Polymeric Dispersing Agents are film-forming polymers with a high resistance to water and saponification, this in contrast to conventional Wetting Agents.高分子量聚合物型分散剂是本身可成膜的高聚物，与传统的润湿剂相比具有高耐水性和耐皂化性。
Calculation method for required amount of solid Dispersant on pigment颜料所需固体分散剂量的计算方法
Inorganic pigments  无机颜料 10% of Oil Absorption value    吸油量的10％
organic pigment blue, green, violet:篮、绿、紫25% of BET value BET 值的25％
yellow, orange, Red: 黄、橙、红 50% of BET value       BET值的50%
Carbon black pigments: 碳黑颜料20% of Oil Absorption value  吸油量的20％
Based on polyurethane  聚氨酯型Chemistry: Polyurethanes (patented)化学成分：聚氨酯（专利产品）
MW ca 5000 - 18000  分子量在5000－18000
n ca. 2 - 10
Based on polyurethane 聚氨酯型
The polyurethane Dispersants have a branched backbone with a three-dimensional net structure. On various places of this net structure different anchoring groups are introduced
聚氨酯型分散剂支化的主链具有三维网状结构。这种网状结构的不同位置引入了不同的锚定基团。
Branched polyurethane有支链的聚氨酯Progress of history of polyurethane polymeric dispersants聚氨酯型分散剂的历史发展
如EFKA40系列
The new generation has started with the development of EFKA-4050. It was presented in 1998. One year later EFKA-4080 was promoted新一代的分散剂伴随着EFKA-4050的开发而开始发展，在1998年已做过介绍，一年后推出了EFKA-4080。
The latest development is EFKA-4060 with very strong viscosity depressing properties
最新开发的EFKA-4060具有非常强的降粘性。Based on polyurethane 聚氨酯型
The main differences between EFKA-4046 and EFKA-4047 and the products of the new generation are mainly in the structure of the anchoring groups. EFKA-4046与EFKA-4047以及与新一代产品的区别主要在于锚定基团的
结构
EFKA-4046: rigid side chains  刚性侧链
EFKA-4050:
EFKA-4080: flexible side chains 弹性侧链
Based on polyurethane 聚氨酯型
In addition EFKA-4060 has prolonged side chains另外EFKA-4060 还有延长的侧链
EFKA-4060: prolonged side chains(non-polar)延长的侧链（非极性）
EFKA-4050: short side chains (non-polar) 短侧链（非极性）Based on polyurethane聚氨酯型
By the extension of the non-polar side chains decreases the interaction between the polar hearts of the neighbouring polymers this results in a strong reduction of the  viscosity, because no build up of a structure take place
通过非极性侧链的伸展减少了相邻聚合物极性中心间的相互作用，因为没有了结构阻力的关系从而导致粘度大大降低。
Chemistry: Polyacrylates (patented)化学结构：聚丙烯酸酯（专利产品）
MW ca. 5000 - 25000 g/mol
分子量 5000－25000g/mol
Alkyl-, Polyether : solubility, compatibility and steric hindrance烷基，聚醚：提供溶解性，相溶性和空间位阻
Fluorocarbon-  : depression of surface tension氟碳化合物：降低表面张力
Alkylamines-  :  anchoring group for pigment surface
烷基胺：吸附颜料表面的锚定基团
Acidic groups  :  anchoring group for inorganic pigments
酸性基团：吸附无机颜料的锚定基团
Based on polyacrylate 丙烯酸酯型
The polyacrylates have linear structures with a C-C backbone that bears various functional side groups and short chains. They bear groups that participate in the anchoring of the pigment. Other play a role in the solvation of the acrylate in the liquid medium, or induce a sterical hindrance
丙烯酸酯分散剂具有带C-C主链的线性结构，这种结构承载着用来锚定颜料的基团，其他链段提供丙烯酸酯在液体介质中的相容性
或形成空间屏蔽作用。
Lineair polyacrylate线性聚丙烯酯
Based on polyacrylate丙烯酸酯型
Linear polyacrylate 线性聚丙烯酸酯
The main differences with polyurethane-based dispersants are the higher molecular weights of the polyacrylates. This together with their excellent compatibility makes them very suitable for those pigments where PU-dispersants fail
与聚氨酯型分散剂的主要区别在于丙烯酸酯分散剂具有更高的分子量。
这一点加上它优异的相容性使得它们非常适合分散那些用聚氨酯分散剂不好分散的颜料。
Based on polyacrylate丙烯酸酯型
The most common used polyacrylates are:最通用的丙烯酸酯分散剂是：
EFKA-4400  (1986)
EFKA-Later developments:
后来开发的有：
EFKA-4403  (1990)
EFKA-4406  (1997)
4401  (1989)
The most innovative acrylate-based Dispersants are developed for the water-based coating area
最具创新的丙烯酸酯分散剂是为水性涂料领域而开发的
Novel Dispersants:  新颖的分散剂
Controlled Free Radical Polymerisation可控自由基聚合物
EFKA’s types of High Molecular Weight Dispersants,EFKA高分子分散剂的类型
Polyurethane, well-known for their strong viscosity reduction of the mill base聚氨酯分散剂以其强烈降低研磨粘度的特点而著名
Polyacrylates, well-known for their wide compatibility丙烯酸酯分散剂以其广泛的相容性而著名
The trend towards VOC-reduced formulations with higher pigment loads - for example Resin Minimal Pigment Concentrates - requires a combination of strong viscosity reduction and wide compatibility.
降低VOC的趋势要求配方含有更高的颜料量，如微脂色母浆。这一技术又要求强降粘性和广泛相容性的结合。
Conventional Polymerisation:传统的聚合物
Initiator (I2), monomer A and B引发剂(I2), 单体A和B
I–A–A–B–A–B–B–A–A–A–A–B–A–B–I no block structures, random in composition and length没有嵌段结构, 单体位置和长度都无规分布
Controlled Polymerisation    可控聚合物Regulator ( R ), monomer A and B 引发剂活性中心R,单体A和单体B
R + x A
A–A–A–A–A–A–A–A–A–A–R  + y B
A–A–A–A–A–A–A–A–A–A–B–B–B–B–B–R
defined block structures in composition and length可控制的嵌段,及其长度.
Conventional copolymer(Random structure)传统的共聚物(无规架构)    Controlled copolymer(block structure)控制型共聚物(嵌段架构)
B-Block  with pigment affinic anchor groups B-段颜料锚定段
A-Block  steric stabiliser/compatible to paint system:
resin en solvents
A-段位阻,相溶性调整,其它性能调整
EFKA Additives B.V. presents two new acrylic based block
copolymer dispersants by Controlled Free Radical Polymerization technology based on special alkoxyamine regulators (NOR).
EFKA助剂公司推出了两种新型丙烯酸类嵌段聚合物型分散剂，这种分散剂的制造采用了基于特殊烷氧基胺活性引发剂的可控自由基聚合技术。
GPC-analysis of polymer molecular weight distribution. Comparison between block copolymer and a random copolymer of similar composition and Mn.
聚合物分子量分布的GPC分析。嵌段共聚物与具有相似成分和分子量的无规架构共聚物的比较。
EFKA-4300 and EFKA-4330 are the first controlled free radical polymeric dispersants launched on an industrial scale and will open a wide range of opportunities for future developments for all kinds of applications.
EFKA-4300与EFKA-4330是最先工业化的可控自由基聚合物型分散剂，这种成就将为未来所有应用技术的发展打开广阔的空间。
This new family of dispersants is based on patented proprietary technology.这些分散剂的新成员都是基于专利技术的专利产品.