Alkali-soluble resins

Alkali-soluble resins n. These are generally lower molecular weight (than conventional lattices) polymers containing about 5-15% carboxyl groups which require amine and/ or cosolvent to solubilizer them. These systems are generally dispersions of micelles rather than true solutions. Abbreviation for ASR. 

M.L. Wang, Z.J. Ma, D. Zhu, D.Y. Zhang, W. Yin, Core-shell latex synthesized by emulsion polymerization using an alkali-soluble resin as sole surfactant. J. App. Polym. Sci. 128,4224— 4230 (2013)... 

Water-Reducible Resins Water-soluble types or lattices or emulsions. Resins which can be diluted (reduced) with water, water-cosolvent mixtures and sometimes with alkali (alkali-soluble resins). (Wicks ZN, Jones FN, Pappas SP (1999) Organic Coatings Science and Technology. 2nd edn. Wiley-Interscience, New York)... 

Alkali-soluble resins Ethylene, propylene, diisobutylene, isobutylene, 2,4,-trimethyl-l-pentene United States 2,378,629 1945 DuPont ... 

The naphthols are more reactive than phenols and resemble resorcinol rather than phenol in many of their reactions [3]. The complexity of the reaction of 1-naphthol with formaldehyde is well known [4] and it has been assumed that cross-linked polymers are formed since reaction can occur at both C-2 and C-4, the positions which are respectively ortho and para to the hydroxyl group. In 1907 Breslauer and Pictet [5] reported obtaining an amorphous product having empirical formula C23H16O3 from the reaction of 1-naphthol with formaldehyde in the presence of potassium carbonate. Abel [6] reported obtaining a brown, brittle, alkali-soluble resin on heating 1-naphthol with formaldehyde in 50% acetic acid containing a small quantity of hydrochloric acid. By way of contrast, 2-naphthol reacts mainly at C-1, and as a result, condenses with formaldehyde under either... 

Solution vehicles consist of water soluble polymers not manufactured by emulsion polymerization. The solution vehicle is an alkali soluble polymer in aqueous solution or a blend of polymers with combined properties into a single waterborne varnish. Soluble polymers are made by free radical polymerization in a processing solvent or as addition or condensation products with heat reaching temperatures up to 265 °C. Solution vehicles are mixtures of soluble resins unlike emulsion polymers. A solution vehicle is used to increase adhesion to film and improve ink printabihty or transfer to meet specific performance requirements. The solution vehicle provides pigment dispersion stabilization, transparency, low film forming temperature, gloss and re-solubility. An alkali soluble resin is a carboxylic acid functional polymer neutralized (solubilized) with ammonia, amine or sodium hydroxide. The add numbers are generally above 100. Ammonia or volatile amines are used in most aqueous inks except for news print inks. After evaporation of the amine, the resin becomes insoluble and resistant to water spray or other water contact. The ink is re-solubilized with alkaline water for the clean-up cycle. For news print ink, the polymers are solubiHzed with sodium hydroxide to maintain re-solubility (open time) of the ink on the press. News print ink pressman prefer unlimited open time and fewer clean-up cycles. Water resistance is not required since ink penetrates the news print paper fibers. 

An emulsifying agent generally produces such an emulsion that the liquid in which it is most soluble forms the external phase. Thus the alkali metal soaps and hydrophilic colloids produce O/W emulsions, oil-soluble resins the W/O type (see emulsion). 

For aqueous inks, the resins are water- or alkali-soluble or dispersible and the solvent is mosdy water containing sufficient alcohol (as much as 25%) to help solubilize the resin. To keep the alkah-soluble resin in solution, pH must be maintained at the correct level. Advances include the development of uv inks. These are high viscosity inks that require no drying but are photocurable by uv radiation. In these formulations, the solvent is replaced by monomers and photoinitiators that can be cross-linked by exposure to uv radiation. The advantage of this system is the complete elimination of volatile organic compounds (VOC) as components of the system and better halftone print quaUty. Aqueous and uv inks are becoming more popular as environmental pressure to reduce VOC increases. 

An adhesive tape for photographic films can be made by using a coating containing a water- or alkali-soluble polymer and ether carboxylate [211]. A light-sensitive resin composition with ether carboxylic acid salt for flexographic plate material shows an improved flexibility and solvent resistance [212]. 

The most widely used positive resists are those that operate on the basis of a dissolution inhibition mechanism. Such resists are generally two-component materials consisting of an alkali soluble matrix resin that is rendered insoluble in aqueous alkaline solutions through addition of a hydrophobic, radiation-sensitive material. Upon irradiation, the hydrophobic moiety may be either removed or converted to an alkali soluble species, allowing selective removal of the irradiated portions of the resist by an alkaline developer. 

An alternative system was recently described by Chandross et al. (35,36) based on optically transparent aqueous-alkali-soluble methyl methacrylate-methacrylic acid copolymer as the inert resin. The dissolution inhibitor was an o-nitrobenzyl carboxylate which undergoes photochemical decomposition to o-nitrosobenzaldehyde plus a carboxylic acid as follows ... 

Water-Based Inks. Approximately 50% of all flexographic inks use water as their primary solvent and diluent. They contain vehicles based on either acrylic emulsions, or hydrosols or an alkali-soluble rosin ester having a high acid number such as partially esterified fiimurated rosin and shellac. Carboxylated acrylic polymers, usually containing some styrene, have largely replaced natural resins because they provide better abrasion and water resistance. Ammonia or other volatile amines are used to solubilize these carboxylated resins and form resin salts. The volatile alkali evaporates from the ink film, rendering the printed matter water resistant. 

Screenable inks have a resin or polymer base and are of three types organic solvent soluble, aqueous alkali soluble, and permanent. Primarily because of pollution requirements and higher solvent costs, the aqueous types have come into greater use. The permanent types are used as solder masks or for marking the boards. Uv-curable inks are also in use. 

Based on alkali-soluble methylolated kraft lignin which was precipitated by acidification and blended with an acid-curing phenolic resin. 

A positive resist composition containing a silsesquioxane resin, (VI), was prepared by Tamura [6] that exhibited increased alkali solubility under the action of acid. 

Conventional photoresists which consist of alkali-soluble novolac resins and photoactive dissolution inhibitors(2.) have excellent dry etching resistance. Hatzakis and his colleagues( .) have investigated such positive photoresists as positive electron beam resists. However, sensitivity to electron beam exposure was not so good(2xl0 5 C/cm2 at 20 kV). 

Phenolic oil-soluble resins also find use as additives to other vehicles to increase adhesion, hardness, and alkali and moisture resistance. The addition of 5-20% to an alkyd will significantly improve this type performance. 

To prepare a suitable resin for adhesive applications, urea is dissolved in formalin (initially neutralized to pH 7.5) to give the desired U/F molar ratio. After boiling under reflux for about 15 min to give demethylol urea and other low-molecular products, the resin is acidified, conveniently with formic acid, to pH 4, and reacted for a further period of 5-20 min. The resulting water-soluble resin with approximately 50% solids content is stabilized by neutralizing to a pH 7.5 with alkali. For use as an aqueous solution, as is normally the case, the resin is then partially dehydrated by vacuum distillation to give a 70% solids content. 

A positive type photosensitive PI resin composition can be made up from a solvent-soluble PI, a poly(amic acid) compound, and by an o-quinonediaz-ide compound.The latter compound releases acid groups when irradiated by UV light. The method of etching is based on the principle that although the PI resin itself is not photosensitive, the photosensitive substance becomes alkali-soluble upon exposure and it is dissolved in an alkali together with the PI resin. ... 

The oil is obtained by expelling. Earlier work (Steger and van Loon, 1935) showed that the commercial oil was not completely soluble in petrol. An ether-soluble resin fraction (6.5%) has been isolated from the seed after extraction with petrol. This fraction is apparently largely removed by alkali refining owing to its acidic nature. 

Heat-reactive resins are more compatible than oil-soluble resins with other polar-coating resins, such as amino, epoxy, and poly(vinyl butyral). They are used in interior-can and drum linings, metal primers, and pipe coatings. The coatings have excellent resistance to solvents, acids, and salts. They can be used over a wide range of temperatures, up to 370°C for short periods of dry heat, and continuously at 150°C. Strong alkalies shonld be avoided. 

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