The application of catalysts in coating auxiliaries

Coating auxiliaries, also known as paint auxiliaries, are auxiliary materials for the preparation of coatings, which can improve the performance of coatings and promote the formation of coating films. There are many types, including catalysts, toughening agents, emulsifiers, thickeners, pigment dispersants, defoamers, leveling agents, anti-crusting agents, matting agents, light stabilizers, anti-mildew agents, anti-static agents (see plastic additives), etc., of which a large amount is catalysts and toughening agents. At present, the research of coating additives to water emulsion paint additives for the focus.

Chinese name: coating additives

Foreign name: Paintadditives

Also known as: paint additives

Used for: Auxiliaries for water emulsion paints

Contents

1 Introduction

2Types

3Details

Drying agents

Toughening agent

Thickening agent

Pigment dispersant

Introduction

Coating additives are those ingredients that are added in small quantities to a coating formulation to control or enhance the performance of the coating. In total, there are about 40 different functional types of coating additives (emulsifiers, dispersants, defoamers, thickeners, anti-cratering agents, drying accelerators, fungicides, etc.), as well as additives composed of different chemical components. Usually the formulation of a coating will contain a variety of additives, and in general the total amount of additives used is less than 5% of the total formulation, but in some cases it may be as high as 10% or more. Due to the relatively high value of additives, the formulation will be designed to minimize the amount of additives used as much as possible.

Types

After years of development, there are many types of coating additives, and they play different roles in each stage of coating production. In the manufacturing stage, there are: initiators, dispersants, ester exchange catalysts; in the reaction process, there are: defoamers, emulsifiers, filtering additives; in the storage stage, there are: anti-crusting agents, anti-sedimentation agents, thickeners, thixotropic agents, anti-floating coloring agents, anti-gelling agents; in the construction stage, there are: leveling agents, anti-cratering agents, anti-sagging agents, hammering additives, flow control agents, plasticizers, defoamers, etc.; in the film-forming stage, there are: agglomeration additives, adhesion promoters (also called adhesion promoters), adhesion promoters, etc. adhesion promoter (also called adhesion enhancer), photoinitiator, light stabilizer, drying, light, slip, matting, curing, cross-linking, catalyst and other additives; to give special features are: flame retardant, biocide, anti-algae, anti-static, conductive, corrosion inhibition, rust prevention and other additives.

In general, according to its use, including adhesion enhancers, anti-adhesive agents, anti-cratering agents, anti-flowering agents, anti-floating agents, defoamers, foam inhibitors, anti-gelling agents, viscosity stabilizers, antioxidants, anti-crusting agents, anti-sagging agents, anti-sedimentation agents, antistatic agents, conductive control agents, anti-mold agents, anticorrosion agents, agglomeration additives, corrosion inhibitors, rust inhibitors, dispersants, wetting agents, drying agents, flame retardants, flow control agents, hammering agents, corrosion inhibitors, rust inhibitors, anti-corrosion agents. flow control agents, hammering additives, drying agents, matting agents, light stabilizers, photosensitizers, optical brightening agents, plasticizers, slip enhancers, anti-scratch agents, thickeners, thixotropic agents, anti-mouse bite agents, other additives.

In addition to the main film-forming substances, color fillers, solvents, a component added to the coating, which can make the coating or coating film of a specific performance to play a significant improvement of the substance. The amount in the coating formula is very small. It is mainly a variety of inorganic compounds and organic compounds, including polymers.

Their names are mostly based on their properties. Those that improve the production process of coatings include wetting agents, dispersants, emulsifiers, defoamers, etc. For improving the storage performance and transportation of coatings, there are anti-sinker, anti-crusting agent, preservative, freeze-thaw stabilizer, etc. To improve coating construction performance and prevent paint film disease, there are anti-sagging agent, leveling agent, floating color and flower prevention agent, defoaming agent, thickening agent, etc. Improve the performance of the coating film and give special performance of ultraviolet absorbers, light stabilizers, flame retardants, anti-static agents, anti-mold agents, etc..

Coating additives can be divided into oil-based coating additives and water-based coating additives. In line with the increasing global attention to environmental protection, the development of water-based coating additives has developed by leaps and bounds. There are more and more new environmentally friendly types of additives. The application is also becoming more and more extensive. It is the mainstream direction of the future development of coating additives.

Detailed introduction

Drying agent

It is a kind of substance that can accelerate the drying of the coating film, and it can promote the absorption of oxygen and the polymerization of double bonds in the dry oil film. It can shorten the drying time of oil film from several days to several hours, facilitate the construction and prevent the staining and damage of the undried film.

Many metal oxides, salts and soaps have a drying effect, but the practical value of lead oxide (red Dan, yellow Dan), manganese dioxide, lead acetate, lead nitrate, manganese sulfate, manganese chloride, manganese borate, manganese acetate, cobalt acetate, cobalt chloride, as well as lead, cobalt, manganese naphthenic soap, linoleic acid soap and rosin acid soap.

As a result of soap drying agent oil solubility is good, so the drying effect is high. Modern paint industry more naphthenic soap for drying agent. Naphthenic acid soap is usually produced by the complex decomposition method.

The amount of drying agent in oil-based coatings depends on the amount of dry oil or semi-dry oil. In dry linseed oil, for example, the amount of lead catalyst (in terms of lead) is 0.4-0.5% of the oil mass; cobalt and manganese are stronger than lead, and the ratio of cobalt, manganese and lead is about 8:1:40. Two or three kinds of metal soaps are used with synergistic effect. In the resin coating, the amount of catalyst must be increased.

Toughening agent

That is, plasticizers (see plastic additives). Coating industry commonly used varieties are diethyl phthalate, dibutyl phthalate, dioctyl phthalate, tributyl phosphate, triphenyl phosphate, trimethylene phosphate and some special varieties.

Thickening agent

A substance that can increase the viscosity of a coating and reduce its fluidity. The important purpose of using thickeners is to reduce the flowing phenomenon during finishing. The thickeners for coatings are mainly the following: ① silica; ② bentonite and organic bentonite (bentonite treated with cationic organic matter); ③ active calcium carbonate particles by surface treatment; ④ hydrogenated castor oil; ⑤ metal soap, such as calcium stearate, aluminum stearate, zinc stearate, etc.; ⑥ polymerized vegetable oil and fatty acid dimer and polyol esters.

Pigment dispersant

Used to prevent pigments from settling or floating. Bentonite and organic bentonite, metal soap, hydrogenated castor oil and other thickening agents can play the role of pigment dispersant. Various surfactants, low molecular weight polyethylene oxide (polyethylene oxide), low viscosity methyl silicone oil, lecithin and its derivatives are also often used.

Levelling agent

Substances that contribute to the formation of a smooth finish. Substances that can reduce the surface tension of coatings generally have the role of leveling agents. Industrial leveling agents have been used fluorinated surfactants, polyacrylates and polyvinyl butyral and other series. General silicone leveling agent is to control the short-wave leveling, reduce surface tension is more obvious; acrylate is to control the long-wave leveling, reduce surface tension amplitude is small.

Anti-crusting agent

The substances that prevent the surface crusting of oil-based coatings in use, such as methyl ethyl ketone oxime and cyclohexanone oxime.