Status and development trends of additives for water-based coatings (2)

other class of dispersants, such as AMP-95, whose chemical name is 2-amino-2-methyl-propylene alcohol. Amino adsorption on the surface of inorgeable particles, hydroxyl outstretched into the water, through the spatial position to block the stabilizing effect. Because of its small molecules, the spatial position resistance is limited. AMP-95 is primarily a PH regulator.
years, the study of dispersants has overcome the problem that high molecular weight produces flocculation, and the development to high molecular weight is one of its trends. For example, the high molecular weight dispersant EFKA-4580
,
, which is legally produced by emulsion polyp, is specially developed for water-based industrial coatings and is suitable for organic and inorganic pigment dispersion with good water resistance.
by acid-base or hydrogen bonding, amino has a good affinity for many pigments. The inlay co-dispersant based on amino acrylic has been paid attention to. Figure 2 shows., tego Dispers 655 wet dispersants are used in water-powered car paints to not only direct pigments, but also prevent aluminum powder from reacting with water.
the development of biodegradable moist dispersants, such as enviroGem AE series bicyto-wet dispersants, is a low-foam moist dispersant due to environmental concerns.
2.2 defoulant
traditional water-based paint defoulant variety is many, generally divided into three categories: mineral oil defoiling agent, polysilica defoiling agent and other types of defossing agent.
mineral oil debugs are commonly used in light and semi-light latex paints.
polysilane defoulant surface pressure is low, defouling and foaming ability is strong, does not affect the gloss, but the use is not at the right time, will cause the coating film shrink hole and heavy coating and other defects.
traditional water-based paint desiccant to be incompatible with water to achieve de-foaming purposes, so it is easy to produce coating surface defects.
recent years, molecular-grade desiccants have been developed.
this deboulant is to de-bubble the active substance directly to form a polymer on the carrier substance. The polymer molecular chain with moist action of hydroxyl, de-foaming active substances distributed around the molecule, the active substance is not easy to gather, and the coating system compatible well. These molecular-grade defoamers are mineral oils ---FoamStar A10 series, silicon----FoamStar A30 series, and non-silicon non-oil polymer --- FoamStar MF series
11
.
it was also reported that this molecular-grade de-foaming agent is a super-branched star-shaped polymer as an incompatible surfactant, in the application of water-based coatings achieved good results.
,000 reported air Products molecular-grade deblisters, such as Surfynol MD 20 and Surfynol DF 37, are acetylene glycols, both moisturizing and defying agents.
, in order to meet the needs of the production of zero-VOC coatings, there are also VOC-free desobbists, such as Agitan 315, Agitan E 255 and so on.2.3 thickener
thickeners are available in a variety of ways and are commonly used in cellulose ethers and their derivatives, combined alkali-soluble expansion thickeners (HASEs) and polyurethane thickeners (HEUR).2.3.1 cellulose ether and its derivatives
according to the introduction, hydroxyethyl cellulose (HEC) was first industrialized by Union Carbide in 1932, has been more than 70 years of history.
At present, cellulose ether and its derivative thickeners are mainly hydroxyethyl cellulose (HEC), methyl hydroxyethyl cellulose (MHEC), ethyl hydroxyethyl cellulose (EHEC), methyl hydroxypropyl cellulose (MHPC), methyl cellulose (MC) and jaundols, these are non-ion thickeners, but also non-ionized water thickeners. Among the most commonly used in latex paint are HEC, such as Aqualon's Natrosol 250 and Union Carbide's Cellusize QP.
hydrophobic modified cellulose (HMHEC) is the introduction of a small amount of long-chain hydrophobic alkyl on the cellulose hydrophobic skeleton to become a joint thickener such as Natrosol Plus Grade 330,331, Cellosize SG-100, Bermocoll EHM-100. Its thickening effect can be comparable to that of cellulose ether thickeners with much larger molecular weight. It improves ICI viscosity and leveling, reducing surface stress, such as HEC surface stress of about 67mN/m and HMHEC surface stress of 55-65mN/m.
2.3.2 alkali-soluble expansion thickener
-alkali-soluble expansion thickener is divided into two categories: non-contracted alkali-soluble swelling thickener (ASE) and contracted alkali-soluble swelling thickener (HASE), both of which are anion thickeners.
non-steroidal ASE is a polyacrylic alkali-soluble emulsion. Such thickeners such as Rohm Haas' ASE 60 and Ciba's Viscalex HV-30.
-type HASE is a hydrophobic polyacrylic alkali-soluble emulsion. HASE thickeners such as Nopco's SN636, Rohm's TT-935, etc. However, this thickener also contains polyurethane and polyurethane-free two categories.
Elements has developed CASE thickeners without VOC and AEO, such as the Rheolate 125.
According to Dow's Olesen and other
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, in color paint, when the amount of color paste is about 4%-8%, the added slurry coating's Stommer viscosity decreased by about 30 KU-40KU, resulting in the same variety of different color paint viscosity, flow and storage stability decline and other issues. The specially developed HASE thickeners UCAR POLYPHONE T-900 and T-901 are insensitive to adding color slurry and are therefore suitable for thickening of paints to be colored and base paints.
for acetate latex paint, UCAR POLYPHONE T-900 can be used alone, or mainly UCAR POLYPHONE T-900, plus a small amount of UCAR POLYPHONE T-901.
for fine particle size pure propylene and phenyl propylene latex paint, should be UCAR POLYPHONE T-901-based, with a small amount of UCAR POLYPHONE T-900..